(U/Th)-He dating of Fe- and Mn-oxide minerals from the Buckskin-Rawhide detachment fault: a new method to determine timing of faulting and fluid flow

NASA Astrophysics Data System (ADS)

Evenson, N. S.; Reiners, P. W.; Spencer, J. E.

2012-12-01

The Buckskin-Rawhide-Harcuvar detachment fault is one of the largest and youngest extensional detachment faults on Earth. It is also associated with abundant deposits of specular hematite with less common Pb, Zn, Ag, Au, and Mn mineralization. Mineralization is thought to be the result of movement of basin brines along the active detachment and subsidiary normal faults, with circulation driven by the heat of the uplifted footwall rocks of the Harcuvar metamorphic core complex. (U/Th)-He dating of specular hematite from the Buckskin-Rawhide detachment system, and Mn oxide minerals from syn-extensional clastic sedimentary rocks directly above the detachment fault, yield ages primarily between 16-10 Ma. These ages are consistent with low-temperature apatite (U/Th)-He and fission track cooling ages from the Rawhide Mountains and other ranges along the detachment. This suggests that Fe and Mn mineralization occurred during a period of rapid footwall exhumation that was underway by ~16 Ma. Aliquots from four hematite samples from the eastern Rawhide Mountains yielded weighted mean ages of 12.1 ± 0.24 Ma, 12.8 ± 0.15 Ma, 13.1 ± 0.17 Ma, and 13.8 ± 0.20 Ma (all uncertainties as 2-sigma standard error). These ages are similar to apatite (U/Th)-He and fission track ages of nearby samples, and display a SW to NE-younging trend when projected parallel to the extension direction, consistent with findings from previous low-T thermochronology studies. Three hematite samples from the western Rawhide and Buckskin Mountains yield more dispersed ages than samples in the eastern part of the core complex. Published apatite fission-track and (U/Th)-He dates from the Rawhide and Buckskin Mountains fall between 16-10 Ma. These ages are interpreted to represent the timing of final tectonic exhumation and fault-driven fluid circulation along the detachment. Average ages for one hematite sample fall in this age range, but one other is younger (9.5 Ma) and another is substantially older (35 Ma). The older age age may indicate the presence of excess He in fluid inclusions. The younger age could indicate that hydrothermal circulation outlasted exhumation by several million years, or other unknown complications to the system. (U/Th)-He analysis of two samples of manganese oxides from the Artillery Mountains yielded weighted mean ages of 13.8 ± 0.20 and 8.12 ± 0.13 Ma. Both ages are consistent with the age of host strata, and suggest that these dates record near-surface mineralization that occurred shortly after the syn-extension host sandstone and conglomerate were deposited. Our results suggest that hematite and manganese oxide (U/Th)-He systems can provide information about the timing of faulting and related fluid flow/mineralization events. With further development in this and other localities, these systems have the potential to provide valuable insights that until now have been difficult or impossible to obtain by other methods.

Nanogeochronology of discordant zircon measured by atom probe microscopy of Pb-enriched dislocation loops

PubMed Central

Peterman, Emily M.; Reddy, Steven M.; Saxey, David W.; Snoeyenbos, David R.; Rickard, William D. A.; Fougerouse, Denis; Kylander-Clark, Andrew R. C.

2016-01-01

Isotopic discordance is a common feature in zircon that can lead to an erroneous age determination, and it is attributed to the mobilization and escape of radiogenic Pb during its post-crystallization geological evolution. The degree of isotopic discordance measured at analytical scales of ~10 μm often differs among adjacent analysis locations, indicating heterogeneous distributions of Pb at shorter length scales. We use atom probe microscopy to establish the nature of these sites and the mechanisms by which they form. We show that the nanoscale distribution of Pb in a ~2.1 billion year old discordant zircon that was metamorphosed c. 150 million years ago is defined by two distinct Pb reservoirs. Despite overall Pb loss during peak metamorphic conditions, the atom probe data indicate that a component of radiogenic Pb was trapped in 10-nm dislocation loops that formed during the annealing of radiation damage associated with the metamorphic event. A second Pb component, found outside the dislocation loops, represents homogeneous accumulation of radiogenic Pb in the zircon matrix after metamorphism. The 207Pb/206Pb ratios measured from eight dislocation loops are equivalent within uncertainty and yield an age consistent with the original crystallization age of the zircon, as determined by laser ablation spot analysis. Our results provide a specific mechanism for the trapping and retention of radiogenic Pb during metamorphism and confirm that isotopic discordance in this zircon is characterized by discrete nanoscale reservoirs of Pb that record different isotopic compositions and yield age data consistent with distinct geological events. These data may provide a framework for interpreting discordance in zircon as the heterogeneous distribution of discrete radiogenic Pb populations, each yielding geologically meaningful ages. PMID:27617295

Cretaceous radiolarians from Baliojong ophiolite sequence, Sabah, Malaysia

NASA Astrophysics Data System (ADS)

Jasin, Basir; Tongkul, Felix

2013-10-01

The Baliojong ophiolite sequence exposed along the Baliojong River in Northern Sabah consists of volcanic rocks, mostly basalts, overlain by sedimentary layers consisting of well-bedded cherts, mudstones and sandstones. The ophiolite sequence occurs as steeply-dipping overturned thrust slices oriented approximately north-south. A total of 42 chert samples were collected from the sedimentary layers. However, most of the samples contain poorly preserved radiolarians. Only nine samples yielded moderately well-preserved radiolarians from three selected thrust slices. A total of 32 taxa were identified. Based on the stratigraphic distribution of selected taxa, the radiolarians can be divided into two assemblage zones. The first assemblage zone is Dictyomitra communis Zone characterized by the occurrence of Dictyomitra communis, Archaeodictyomitra (?) lacrimula, Sethocapsa (?) orca, Dictyomitra pseudoscalaris, and Pantanellium squinaboli. The assemblage indicates Barremian to Aptian in age. The second assemblage zone Pseudodictyomitra pseudomacrocephala Zone contains Pseudodictyomitra pseudomacrocephala, Dictyomitra gracilis, Dictyomitra montesserei, Xitus mclaughlini, and Dictyomitra obesa. This assemblage indicates an age of Albian and the presence of Pseudodictyomitra tiara suggests the age may extend up to Cenomanian. Each thrust slice yielded more or less similar radiolarian assemblages indicating that they all came from the same sedimentary layers.

Geology and ground-water resources of Goshen County, Wyoming; Chemical quality of the ground water

USGS Publications Warehouse

Rapp, J.R.; Visher, F.N.; Littleton, R.T.; Durum, W.H.

1957-01-01

Goshen County, which has an area of 2,186 square miles, lies in southeastern Wyoming. The purpose of this study was to evaluate the ground-water resources of the county by determining the character, thickness, and extent of the waterbearing materials; the source, occurrence, movement, quantity, and quality of the ground water; and the possibility of developing additional ground water. The rocks exposed in the area are sedimentary and range in age from Precambrian to Recent. A map that shows the areas of outcrop and a generalized section that summarizes the age, thickness, physical character, and water supply of these formations are included in the report. Owing to the great depths at which they lie beneath most of the county, the formations older than the Lance formation of Late Cretaceous age are not discussed in detail. The Lance formation, of Late Cretaceous age, which consists mainly of beds of fine-grained sandstone and shale, has a maximum thickness of about 1,400 feet. It yields water, which usually is under artesian pressure, to a large number of domestic and stock wells in the south-central part of the county. Tertiary rocks in the area include the Chadron and Brule formations of Oligocene age, the Arikaree formation of Miocene age, and channel deposits of Pliocene age. The Chadron formation is made up of two distinct units: a lower unit of highly variegated fluviatile deposits that has been found only in the report area; and an upper unit that is typical of the formation as it occurs in adjacent areas. The lower unit, which ranges in thickness from a knife edge to about 95 feet, is not known to yield water to wells, but its coarse-grained channel deposits probably would yield small quantities of water to wells. The upper unit, which ranges in thickness from a knife edge to about 150 feet, yields sufficient quantities of water for domestic and stock uses from channel deposits of sandstone under artesian pressure. The Brule formation, which is mainly a siltstone, ranges in thickness from a knife edge to about 450 feet and yields water to domestic and stock wells from fractures and from lenses of sandstone. The Arikaree formation ranges in thickness from a knife edge to about 1,000 feet, and yields water to several domestic and stock wells in the northwestern part of the area. The Pliocene channel deposits, which probably do not exceed 25 feet in thickness, are not a source of water for wells in Goshen County. The upland deposits, which are mainly of Pleistocene age, generally are dry and do not serve as aquifers; however, test drilling revealed several deep, buried channels occupied by deposits which probably would yield moderate quantities of water to wells if a sufficient saturated thickness were penetrate The deposits of the third terrace, which are of Pleistocene age, range in thickness from a knife edge to about 210 feet and yield water to a large number of irrigation wells in the area. The flood-plain deposits, which are of Pleistocene and Recent age, range in thickness from a knife edge to about 200 feet. Those in the valley of the North Platte River yield abundant water to many large supply wells. The flood-plain deposits along the valley of Rawhide Creek consist mainly of fine-grained materials and yield large supplies of water to well only in the lower stretches of the creek valley near its confluence with the valley of the North Platte River. The deposits along the valleys of Horse and Bear Creeks generally are relatively thin and fine grained. In the vicinity of Ls grange, however, the deposits, which are about 45 feet thick, yield moderate, supplies of water to several irrigation wells. Other Recent deposits in the area--dune sand, loesslike deposits, and slope wash--generally are fine grained and relatively thin and, hence, are not important sources of ground water. The unconsolidated sand and gravel of the flood-plain and terrace deposits are the principal aquifers in the area. In some places

Ar-40/Ar-39 and U-Th-Pb dating of separated clasts from the Abee E4 chondrite

NASA Technical Reports Server (NTRS)

Bogard, D. D.; Unruh, D. M.; Tatsumoto, M.

1983-01-01

Ar-40/Ar-39 and U-Th-Pb are investigated for three clasts from the Abee (E4) enstatite chondrite, yielding Ar-40/Ar-39 plateau ages (and/or maximum ages) of 4.5 Gy, while two of the clasts give average ages of 4.4 Gy. The 4.4-4.5 Gy range does not resolve possible age differences among the clasts. The U-Th-Pb data are consistent with the interpretation that initial clast formation occurred 4.58 Gy ago, and that the clasts have since remained closed systems which have been contaminated with terrestrial Pb. The thermal history of Abee deduced from Ar data seems consistent with that deduced from magnetic data, suggesting that various Abee components experienced separate histories until brecciation no later than 4.4 Gy ago, experiencing no significant subsequent heating.

Newly Described Tephra Provide Middle Pleistocene Age Constraints to Stegodon Fossils in West (Indonesian) Timor

NASA Astrophysics Data System (ADS)

Jensen, B. J. L.; Dufrane, A.; Mark, D.; Zaim, Y.; Rizal, Y.; Aswan, A.; Hascaryo, A.; Ciochon, R.; Gunnell, G.; Larick, R.; Zonnveld, J. P.

2017-12-01

As the Asian proboscidian Stegodon dispersed across Island Southeast Asia during the Pleistocene, multiple forms developed. On Timor, a southerly island east of Wallace's Line, the Ainaro gravels have yielded a highly dwarfed S. timorensis and a larger S. `trigonocephalus.' During a half-century of exploration, the age of the fossil bearing gravels remains in question, with only one age determination of >130 ka derived from six 230Th- 238U dates on a tusk fragment found in the Raebia area (Louys et al. 2016). Here we present radiometric ages for two tephra deposits bracketing Ainaro gravels at Raebia, a S. timorensis fossil locality 8 km northeast of Atambua city. The Raebia ravine exposes 2-10 meters of coarse-grained gravels incised into silt and clay deposits, bracketed by two indurated and largely devitrified tephras. Some intact glass was present to geochemically characterize each unit, which are both high-silica rhyolites. Biotite and zircons for 40Ar/39Ar and laser ablation U-Pb dating were extracted from the upper unit (Raebia Tuff 1; RT1), and zircons from the lower unit (Raebia Tuff 2; RT2). RT1 had zircons with two distinct age populations, but the youngest yield a 230Th deficiency corrected 206Pb/238U age of 665 ± 19 ka, (2s, n = 23, MSWD = 0.81), consistent with the 40Ar/39Ar age 614.9 ± 16.4 ka (2s, full external precision). Preliminary zircon dates on RT2 are more problematic, providing a large range that suggests inheritance by xenoliths and/or locally-sourced detrital zircons. However, a single zircon yielded 230Th deficiency corrected 206Pb/238U age of 708 ± 66 ka (2s, n=17, MSWD = 0.41), which is stratigraphically consistent. These are the first reliable age constraints on a higher elevation Ainaro gravel terrace and fossils they contain. The only other direct ages on the gravels are 230Th- 238U dates on lower terraces interbedded with coral, ranging from 130 ka to Holocene in age (Roosmawati and Harris 2009). These two newly described and dated tephra are likely regionally distributed and may represent important stratigraphic horizons for this portion of Southern Wallacea. They also provide useful data for calculating uplift rates for the region from the middle Pleistocene.

A BAYESIAN APPROACH TO DERIVING AGES OF INDIVIDUAL FIELD WHITE DWARFS

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Malley, Erin M.; Von Hippel, Ted; Van Dyk, David A., E-mail: ted.vonhippel@erau.edu, E-mail: dvandyke@imperial.ac.uk

2013-09-20

We apply a self-consistent and robust Bayesian statistical approach to determine the ages, distances, and zero-age main sequence (ZAMS) masses of 28 field DA white dwarfs (WDs) with ages of approximately 4-8 Gyr. Our technique requires only quality optical and near-infrared photometry to derive ages with <15% uncertainties, generally with little sensitivity to our choice of modern initial-final mass relation. We find that age, distance, and ZAMS mass are correlated in a manner that is too complex to be captured by traditional error propagation techniques. We further find that the posterior distributions of age are often asymmetric, indicating that themore » standard approach to deriving WD ages can yield misleading results.« less

Life-table methods for detecting age-risk factor interactions in long-term follow-up studies.

PubMed

Logue, E E; Wing, S

1986-01-01

Methodological investigation has suggested that age-risk factor interactions should be more evident in age of experience life tables than in follow-up time tables due to the mixing of ages of experience over follow-up time in groups defined by age at initial examination. To illustrate the two approaches, age modification of the effect of total cholesterol on ischemic heart disease mortality in two long-term follow-up studies was investigated. Follow-up time life table analysis of 116 deaths over 20 years in one study was more consistent with a uniform relative risk due to cholesterol, while age of experience life table analysis was more consistent with a monotonic negative age interaction. In a second follow-up study (160 deaths over 24 years), there was no evidence of a monotonic negative age-cholesterol interaction by either method. It was concluded that age-specific life table analysis should be used when age-risk factor interactions are considered, but that both approaches yield almost identical results in absence of age interaction. The identification of the more appropriate life-table analysis should be ultimately guided by the nature of the age or time phenomena of scientific interest.

Effect of intensified feeding of heifer calves on growth, pubertal age, calving age, milk yield, and economics.

PubMed

Davis Rincker, L E; Vandehaar, M J; Wolf, C A; Liesman, J S; Chapin, L T; Weber Nielsen, M S

2011-07-01

The objective of this study was to determine if increasing the energy and protein intake of heifer calves would affect growth rates, age at puberty, age at calving, and first lactation milk yield. A second objective was to perform an economic analysis of this feeding program using feed costs, number of nonproductive days, and milk yield data. Holstein heifer calves born at the Michigan State Dairy Cattle Teaching and Research Center were randomly assigned to 1 of 2 dietary treatments (n=40/treatment) that continued from 2 d of age until weaning at 42 d of age. The conventional diet consisted of a standard milk replacer [21.5% crude protein (CP), 21.5% fat] fed at 1.2% of body weight (BW) on a dry matter basis and starter grain (19.9% CP) to attain 0.45 kg of daily gain. The intensive diet consisted of a high-protein milk replacer (30.6% CP, 16.1% fat) fed at 2.1% of BW on a dry matter basis and starter grain (24.3% CP) to achieve 0.68 kg of daily gain. Calves were gradually weaned from milk replacer by decreasing the amount offered for 5 and 12 d before weaning for the conventional and intensive diets, respectively. All calves were completely weaned at 42 d of age and kept in hutches to monitor individual starter consumption in the early postweaning period. Starting from 8 wk of age, heifers on both treatments were fed and managed similarly for the duration of the study. Body weight and skeletal measurements were taken weekly until 8 wk of age, and once every 4 wk thereafter until calving. Calves consuming the intensive diet were heavier, taller, and wider at weaning. The difference in withers height and hip width was carried over into the early post-weaning period, but a BW difference was no longer evident by 12 wk of age. Calves fed the intensive diet were younger and lighter at the onset of puberty. Heifers fed the high-energy and protein diet were 15 d younger at conception and 14 d younger at calving than heifers fed the conventional diet. Body weight after calving, daily gain during gestation, withers height at calving, body condition score at calving, calving difficulty score, and calf BW were not different. Energy-corrected, age-uncorrected 305-d milk yield was not different, averaging 9,778 kg and 10,069 kg for heifers fed the conventional and intensive diets, respectively. However, removing genetic variation in milk using parent average values as a covariate resulted in a tendency for greater milk from heifers fed the intensive diet. Preweaning costs were higher for heifers fed the intensive diet. However, total costs measured through first lactation were not different. Intensified feeding of calves can be used to decrease age at first calving without negatively affecting milk yield or economics. Copyright © 2011 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

K-Ar geochronology of basement rocks on the northern flank of the Huancabama deflection, Ecuador

USGS Publications Warehouse

Feininger, Tomas; Silberman, M.L.

1982-01-01

The Huancabamba deflection, a major Andean orocline located at the Ecuador-Peru border, constitutes an important geologic boundary on the Pacific coast of South America. Crust to the north of the deflection is oceanic and the basement is composed of basic igneous rocks of Cretaceous age, whereas crust to the south is continental and felsic rocks of Precambrian to Cretaceous age make up the basement. The northern flank of the Huancabamba Deflection in El Oro Province, Ecuador, is underlain by Precambrian polymetamorphic basic rocks of the Piedras Group; shale, siltstone, sandstone, and their metamorphosed equivalents in the Tahuin Group (in part of Devonian age); concordant syntectonic granitic rocks; quartz diorite and alaskite of the Maroabeli pluton; a protrusion of serpentinized harzburgite that contains a large inclusion of blueschist-facies metamorphic rocks, the Raspas Formation, and metamorphic rocks north of the La Palma fault. Biotite from gneiss of the Tahuin Group yields a Late Triassic K-Ar age (210 ? 8 m.y.). This is interpreted as an uplift age and is consistent with a regional metamorphism of Paleozoic age. A nearby sample from the Piedras Group that yielded a hornblende K-Ar age of 196 ? 8 m.y. was affected by the same metamorphic event. Biotite from quartz diorite of the mesozonal Maroabeli pluton yields a Late Triassic age (214 ? 6 m.y.) which is interpreted as an uplift age which may be only slightly younger than the age of magmatic crystallization. Emplacement of the pluton may postdate regional metamorphism of the Tahuin Group. Phengite from politic schist of the Raspas Formation yields an Early Cretaceous K-Ar age (132 ? 5 m.y.). This age is believed to date the isostatic rise of the encasing serpentinized harzburgite as movement along a subjacent subduction zone ceased, and it is synchronous with the age of the youngest lavas of a coeval volcanic arc in eastern Ecuador. A Late Cretaceous K-Ar age (74.4 ? 1.1 m.y.) from hornblende in amphibolite north of the La Palma fault shows that rocks there are distinct from the superficially similar rocks of the Tahuin Group to the south. Biotite from schist in the Eastern Andean Cordillera yields an Early Eocene age (56.6 ? 1.6 m.y.). Metamorphic rocks in the northern part of the Eastern Andean Cordillera are Cretaceous in age and were metamorphosed in part in early Tertiary time. They are unrelated to and were metamorphosed later than any of the diverse rocks exposed on the northern flank of the Huancabamba Deflection.

Food and fitness: associations between crop yields and life-history traits in a longitudinally monitored pre-industrial human population.

PubMed

Hayward, Adam D; Holopainen, Jari; Pettay, Jenni E; Lummaa, Virpi

2012-10-22

Severe food shortage is associated with increased mortality and reduced reproductive success in contemporary and historical human populations. Studies of wild animal populations have shown that subtle variation in environmental conditions can influence patterns of mortality, fecundity and natural selection, but the fitness implications of such subtle variation on human populations are unclear. Here, we use longitudinal data on local grain production, births, marriages and mortality so as to assess the impact of crop yield variation on individual age-specific mortality and fecundity in two pre-industrial Finnish populations. Although crop yields and fitness traits showed profound year-to-year variation across the 70-year study period, associations between crop yields and mortality or fecundity were generally weak. However, post-reproductive individuals of both sexes, and individuals of lower socio-economic status experienced higher mortality when crop yields were low. This is the first longitudinal, individual-based study of the associations between environmental variation and fitness traits in pre-industrial humans, which emphasizes the importance of a portfolio of mechanisms for coping with low food availability in such populations. The results are consistent with evolutionary ecological predictions that natural selection for resilience to food shortage is likely to weaken with age and be most severe on those with the fewest resources.

Bovine renal lipofuscinosis: prevalence, genetics and impact on milk production and weight at slaughter in Danish cattle.

PubMed

Agerholm, Jørgen S; Christensen, Knud; Nielsen, Søren Saxmose; Flagstad, Pia

2009-02-12

Bovine renal lipofuscinosis (BRL) is an incidental finding in cattle at slaughter. Condemnation of the kidneys as unfit for human consumption was until recently considered the only implication of BRL. Recent studies have indicated a negative influence on the health of affected animals. The present study investigated the prevalence, genetics and effect of BRL on milk yield and weight at slaughter. BRL status of slaughter cattle was recorded at four abattoirs during a 2-year-period. Data regarding breed, age, genetic descent, milk yield and weight at slaughter were extracted from the Danish Cattle Database. The prevalence of BRL was estimated stratified by breed and age-group. Furthermore, total milk yield, milk yield in last full lactation and weight at slaughter were compared for BRL-affected and non-affected Danish Holsteins and Danish Red cattle. 433,759 bovines were slaughtered and 787 of these had BRL. BRL was mainly diagnosed in Danish Red, Danish Holstein and crossbreds. The age of BRL affected animals varied from 11 months to 13 years, but BRL was rarely diagnosed in cattle less than 2 years of age.The total lifelong energy corrected milk (ECM) yields were 3,136 and 4,083 kg higher for BRL affected Danish Red and Danish Holsteins, respectively. However, the median life span of affected animals was 4.9 months longer, and age-corrected total milk yield was 1,284 kg lower for BRL affected Danish Red cows. These cows produced 318 kg ECM less in their last full lactation. Weight at slaughter was not affected by BRL status.The cases occurred in patterns consistent with autosomal recessive inheritance and several family clusters of BRL were found. Analysis of segregation ratios demonstrated the expected ratio for Danish Red cattle, but not for Danish Holsteins. The study confirmed that BRL is a common finding in Danish Holsteins and Danish Red cattle at slaughter. The disorder is associated with increased total milk yield due to a longer production life. However, a reduced milk yield was detected in the end of the production life in Danish Red. The study supports that BRL is inherited autosomal recessively in the Danish Red breed and Danish Holsteins, but with incomplete penetrance of the genotype in Danish Holsteins.

Sea-level history and tectonic uplift during the last-interglacial period (LIG): Inferred from the Bab al-Mandab coral reef terraces, southern Red Sea

NASA Astrophysics Data System (ADS)

Al-Mikhlafi, Ahmed Saif; Edwards, Lawrence R.; Cheng, Hai

2018-02-01

Results of U-series dating of late Pleistocene raised coral reef terraces from the Bab al-Mandab area, define two distinct groups: (1) well-preserved aragonitic fossil corals recorded from the Al-Hajaja terrace (Tr3) yield ages for last-interglacial period (LIG); and (2) calcitic fossil corals recovered from Perim Island terrace (Tr1) show varying degrees of U-series open system behavior and yield coral assemblage ages of LIG and older ages. Fossil corals from Tr1 are recrystallized corals, have anomalously high initial δ234U ranged from (152 ± 2‰ to 287 ± 7‰), corresponding to ages of ∼120 ka and ∼406 ka, respectively. Applying age reliability criteria on the current data suggest majority of the ages cannot be considered reliable and all are suspected for open system behavior associated with U loss/addition that significantly affects the 230Th/U ages. The diagenesis shown by these corals occurred probably due to extensive interaction of fossil corals with freshwater during the wet periods prevailed in southern Arabia coeval with the African monsoon, which led to U loss. Post-depositional U loss suggest (230Th/238U) increase, which shift the U-Th ages to unexpectedly higher levels as it is shown here. Measured elevation at the Al-Hajaja terrace (Tr3) is ∼4 ± 2 m above present sea level (apsl) consistent with eustatic sea level changes and indicates that the Bab al-Mandab area is stable at least since the LIG period. The Perim Island terrace (Tr1) is at elevation of 7 ± 2 m apsl; its reef yields diageneticaly-altered corals of multiple ages and cannot be used for sea level reconstructions.

(U-Th)/He ages of phosphates from Zagami and ALHA77005 Martian meteorites: Implications to shock temperatures

NASA Astrophysics Data System (ADS)

Min, Kyoungwon; Farah, Annette E.; Lee, Seung Ryeol; Lee, Jong Ik

2017-01-01

Shock conditions of Martian meteorites provide crucial information about ejection dynamics and original features of the Martian rocks. To better constrain equilibrium shock temperatures (Tequi-shock) of Martian meteorites, we investigated (U-Th)/He systematics of moderately-shocked (Zagami) and intensively shocked (ALHA77005) Martian meteorites. Multiple phosphate aggregates from Zagami and ALHA77005 yielded overall (U-Th)/He ages 92.2 ± 4.4 Ma (2σ) and 8.4 ± 1.2 Ma, respectively. These ages correspond to fractional losses of 0.49 ± 0.03 (Zagami) and 0.97 ± 0.01 (ALHA77005), assuming that the ejection-related shock event at ∼3 Ma is solely responsible for diffusive helium loss since crystallization. For He diffusion modeling, the diffusion domain radius is estimated based on detailed examination of fracture patterns in phosphates using a scanning electron microscope. For Zagami, the diffusion domain radius is estimated to be ∼2-9 μm, which is generally consistent with calculations from isothermal heating experiments (1-4 μm). For ALHA77005, the diffusion domain radius of ∼4-20 μm is estimated. Using the newly constrained (U-Th)/He data, diffusion domain radii, and other previously estimated parameters, the conductive cooling models yield Tequi-shock estimates of 360-410 °C and 460-560 °C for Zagami and ALHA77005, respectively. According to the sensitivity test, the estimated Tequi-shock values are relatively robust to input parameters. The Tequi-shock estimates for Zagami are more robust than those for ALHA77005, primarily because Zagami yielded intermediate fHe value (0.49) compared to ALHA77005 (0.97). For less intensively shocked Zagami, the He diffusion-based Tequi-shock estimates (this study) are significantly higher than expected from previously reported Tpost-shock values. For intensively shocked ALHA77005, the two independent approaches yielded generally consistent results. Using two other examples of previously studied Martian meteorites (ALHA84001 and Los Angeles), we compared Tequi-shock and Tpost-shock estimates. For intensively shocked meteorites (ALHA77005, Los Angeles), the He diffusion-based approach yield slightly higher or consistent Tequi-shock with estimations from Tpost-shock, and the discrepancy between the two methods increases as the intensity of shock increases. The reason for the discrepancy between the two methods, particularly for less-intensively shocked meteorites (Zagami, ALHA84001), remains to be resolved, but we prefer the He diffusion-based approach because its Tequi-shock estimates are relatively robust to input parameters.

Argon behaviour in an inverted Barrovian sequence, Sikkim Himalaya: The consequences of temperature and timescale on 40Ar/39Ar mica geochronology

NASA Astrophysics Data System (ADS)

Mottram, Catherine M.; Warren, Clare J.; Halton, Alison M.; Kelley, Simon P.; Harris, Nigel B. W.

2015-12-01

40Ar/39Ar dating of metamorphic rocks sometimes yields complicated datasets which are difficult to interpret in terms of timescales of the metamorphic cycle. Single-grain fusion and step-heating data were obtained for rocks sampled through a major thrust-sense shear zone (the Main Central Thrust) and the associated inverted metamorphic zone in the Sikkim region of the eastern Himalaya. This transect provides a natural laboratory to explore factors influencing apparent 40Ar/39Ar ages in similar lithologies at a variety of metamorphic pressure and temperature (P-T) conditions. The 40Ar/39Ar dataset records progressively younger apparent age populations and a decrease in within-sample dispersion with increasing temperature through the sequence. The white mica populations span 2-9 Ma within each sample in the structurally lower levels (garnet grade) but only 0-3 Ma at structurally higher levels (kyanite-sillimanite grade). Mean white mica single-grain fusion population ages vary from 16.2 ± 3.9 Ma (2σ) to 13.2 ± 1.3 Ma (2σ) from lowest to highest levels. White mica step-heating data from the same samples yields plateau ages from 14.27 ± 0.13 Ma to 12.96 ± 0.05 Ma. Biotite yield older apparent age populations with mean single-grain fusion dates varying from 74.7 ± 11.8 Ma (2σ) at the lowest structural levels to 18.6 ± 4.7 Ma (2σ) at the highest structural levels; the step-heating plateaux are commonly disturbed. Temperatures > 600 °C at pressures of 0.4-0.8 GPa sustained over > 5 Ma, appear to be required for white mica and biotite ages to be consistent with diffusive, open-system cooling. At lower temperatures, and/or over shorter metamorphic timescales, more 40Ar is retained than results from simple diffusion models suggest. Diffusion modelling of Ar in white mica from the highest structural levels suggests that the high-temperature rocks cooled at a rate of 50-80 °C Ma- 1, consistent with rapid thrusting, extrusion and exhumation along the Main Central Thrust during the mid-Miocene.

Geochronology and eruptive history of the Katmai volcanic cluster, Alaska Peninsula

USGS Publications Warehouse

Hildreth, Wes; Lanphere, Marvin A.; Fierstein, Judy

2003-01-01

In the Katmai district of the Alaska Peninsula, K–Ar and 40Ar/39Ar ages have been determined for a dozen andesite–dacite stratocones on the arc front and for 11 rear-arc volcanoes, 10 of which are monogenetic. Tied to mapping and stratigraphic studies, our dating emphasized proximal basal lavas that rest on basement rocks, in order to estimate ages of inception of each polygenetic cone. Oldest among arc-front cones is Alagogshak Volcano (690–43 ka), succeeded in the Holocene by the active Mount Martin cone. Mount Mageik consists of four overlapping subedifices, basal lavas of which give ages of 93, 71, and 59 ka, and Holocene. The three small prehistoric cones of Trident Volcano yield ages of 143, 101–58, and 44 ka. Falling Mountain and Mount Cerberus, dacite domes near the 1912 Novarupta vent, are related compositionally to the Trident group and give ages of 70 ka and 114 ka. Mount Katmai, which underwent caldera collapse in 1912, consists of two subedifices that overlapped in space and time, and is the only arc-front center here to include basalt and rhyolite; one cone began by 90 ka, the other by 47 ka. Snowy Mountain also consists of two contiguous cones, which started around 200 and 171 ka, respectively, the younger remaining active into the Holocene. Devils Desk, the only mafic cone on the arc front, was short-lived at about 245 ka. In the rear-arc, (1) Mount Griggs produced mafic-to-silicic andesite in several episodes between 292 ka and the Holocene; (2) the Savonoski River cluster includes a Pliocene dacite dome and five small mafic cones (390–88 ka); (3) Gertrude Creek cone (49.8% SiO2) yields an age of 500 ka; and (4) the Saddlehorn Creek cluster includes five Pliocene basalt-to-andesite remnants. Eruptive volumes were reconstructed, permitting estimates of average eruption rates for edifice lifetimes. Since the mid Pleistocene, total volume erupted along the arc front here is 210±47 km3 and in the rear-arc 39±6 km3, of which Mount Griggs alone accounts for 35±5 km3. Most productive has been Mount Katmai at 70±18 km3, yielding a rate of ∼1 km3/kyr, followed by Mount Mageik (0.33 km3/kyr) and Mount Griggs (0.3 km3/kyr since 50 ka).  

Sm-Nd Isotopic Systematics of Troctolite 76335

NASA Technical Reports Server (NTRS)

Edmunson, J.; Nyquist, L. E.; Borg, L. E.

2007-01-01

A study of the Sm-Nd isotopic systematics of lunar Mg-suite troctolite 76335 was undertaken to further establish the early chronology of lunar magmatism. Because the Rb-Sr isotopic systematics of similar sample 76535 yielded an age of 4570 +/- 70 Ma [2, lambda = 1.402 x 10(exp -11)], 76335 was expected to yield an old age. In contrast, the Sm-Nd and K-Ar ages of 76535 indicate that the sample is approximately 4260 Ma old, one of the youngest ages obtained for a Mg-suite rock. This study establishes the age of 76335 and discusses the constraints placed on its petrogenesis by its Sm-Nd isotope systematics. The Sm-Nd isotopic system of lunar Mg-suite troctolite 76335 indicates an age of 4278 +/- 60 Ma with an initial epsilon (sup 143)(sub Nd) value of 0.06 +/- 0.39. These values are consistent with the Sm-Nd isotopic systematics of similar sample 76535. Thus, it appears that a robust Sm-Nd age can be determined from a highly brecciated lunar sample. The Sm-Nd isotopic systematics of troctolites 76335 and 76535 appear to be different from those dominating the Mg-suite norites and KREEP basalts. Further analysis of the Mg-suite must be completed to reveal the isotopic relationships of these early lunar rocks.

Age differences in responses to conflict in the workplace.

PubMed

Davis, Mark H; Kraus, Linda A; Capobianco, Sal

2009-01-01

Socioemotional selectivity theory (SST) has been used successfully to explain age differences in interpersonal conflict behavior: older adults are generally less likely to engage in destructive responses, and more likely to employ nonconfrontational ones. However, this research has focused almost exclusively on conflict with intimates (spouses, family, friends), and has typically not examined conflict in the workplace. The present investigation uses behavior ratings made by bosses, peers, and subordinates of 2513 working adults to examine the association between age and workplace conflict behavior; more specifically, it tests three hypotheses generated from socioemotional selectivity theory. Consistent with predictions, raters generally agreed that older working adults were more likely to engage in nonconfrontational responses (yielding, delaying responding); also as expected, older and younger respondents did not consistently differ in their efforts to constructively solve conflict. Unexpectedly, little evidence was found that older adults engage in less active destructive behavior.

Evidence for a Mid-Crustal Continental Suture and Implications for Multistage (U)HP exhumation, Liverpool Land, East Greenland

NASA Astrophysics Data System (ADS)

Johnston, S.; Brueckner, H.; Gehrels, G.; Manthei, C.; Hacker, B.; Kylander-Clark, A.; Hartz, E. H.

2008-12-01

The East Greenland Caledonides consists of a series of west-directed sheets that formed from 460-360 Ma as Baltica subducted westward beneath Laurentia, and offer an opportunity to study high- and ultrahigh- pressure exhumation in orogenic hangingwalls. The Liverpool Land (LL) gneiss complex, 100 km east of the nearest Caledonian gneisses, provides a window into the deepest levels of the Greenland Caledonides. From the bottom up, the LL tectonostratigraphy is comprised of the eclogite-bearing Tvaerdal orthogneiss and the granulite-facies Jaettedal paragneiss structurally below the top-N Hurry Inlet Detachment. We present new thermobarometry and U/Pb zircon and titanite geochronology from the LL gneisses to define the tectonostratigraphy, continental affinity, and exhumation histories of the LL gneiss complex. The Tvaerdal orthogneiss consists of felsic orthogneisses that host rare ultramafic bodies (Fo92) and mafic boudins that yield peak pressures of >25 kbar at 800°C. Host gneiss zircons dated using LA-MC- ICPMS yield 1676 ± 17 Ma (2s) cores with 403 ± 6 Ma (2s) rims that suggest Mesoproterozoic emplacement of the original intrusive body followed by late-Caledonian deformation. The Tvaerdal orthogneiss also includes voluminous decompression melts; one yielded a TIMS U/Pb titanite age of 387.5 ± 2.2 Ma (2s). The structurally higher Jaettedal paragneiss consists of pelitic gneisses interlayered with granodioritic-dioritic orthogneisses. The Jaettedal-Tvaerdal contact is petrologically abrupt and concordant to regional foliation and lacks sub-amphibolite-facies displacement. Aluminum silicate-bearing pelitic assemblages within the Jaettedal paragneiss yield peak metamorphic conditions of 10-11 kbar at 750- 800°C. U/Pb age maps made using LA-MC-ICPMS from three paragneisses reveal Mesoproterozoic- Archean detrital cores with Caledonian rim overgrowths that cluster between 439-434 Ma. An amphibolite restite from the Jaettedal paragneiss yielded a TIMS U/Pb titanite age of 413 ± 1 Ma (2s). This new data defines two distinct LL gneiss complexes beneath the Hurry Inlet Detachment and suggests the presence of a previously unidentified continental suture between the Tvaerdal and Jaettedal gneisses. Similar timing, metamorphic conditions, and detrital zircon signatures to units farther inland, as well as the presence of Archean detrital zircons indicate a Laurentian continental affinity for Jaettedal paragneiss. In contrast, ~400 Ma (U)HP metamorphism and Mesoproterozoic basement ages, which have not been identified in Laurentia, suggests correlation of the Tvaerdal gneiss with the Baltican-derived Western Gneiss Region. Furthermore, the suture between the Tvaerdal and Jaettedal gneisses, with kinematics that remain undefined, represents a structure responsible for the juxtaposition of the younger (U)HP Tvaerdal orthogneiss against the older mid-crustal Jaettedal paragneiss, and the initial stages of (U)HP exhumation from mantle depths to lower-middle crustal levels. This initial exhumation may have triggered subsequent displacement along the Hurry Inlet Detachment responsible for the final stages of (U)HP exhumation in the upper crust.

Activin Decoy Receptor ActRIIB:Fc Lowers FSH and Therapeutically Restores Oocyte Yield, Prevents Oocyte Chromosome Misalignments and Spindle Aberrations, and Increases Fertility in Midlife Female SAMP8 Mice.

PubMed

Bernstein, Lori R; Mackenzie, Amelia C L; Lee, Se-Jin; Chaffin, Charles L; Merchenthaler, István

2016-03-01

Women of advanced maternal age (AMA) (age ≥ 35) have increased rates of infertility, miscarriages, and trisomic pregnancies. Collectively these conditions are called "egg infertility." A root cause of egg infertility is increased rates of oocyte aneuploidy with age. AMA women often have elevated endogenous FSH. Female senescence-accelerated mouse-prone-8 (SAMP8) has increased rates of oocyte spindle aberrations, diminished fertility, and rising endogenous FSH with age. We hypothesize that elevated FSH during the oocyte's FSH-responsive growth period is a cause of abnormalities in the meiotic spindle. We report that eggs from SAMP8 mice treated with equine chorionic gonadotropin (eCG) for the period of oocyte growth have increased chromosome and spindle misalignments. Activin is a molecule that raises FSH, and ActRIIB:Fc is an activin decoy receptor that binds and sequesters activin. We report that ActRIIB:Fc treatment of midlife SAMP8 mice for the duration of oocyte growth lowers FSH, prevents egg chromosome and spindle misalignments, and increases litter sizes. AMA patients can also have poor responsiveness to FSH stimulation. We report that although eCG lowers yields of viable oocytes, ActRIIB:Fc increases yields of viable oocytes. ActRIIB:Fc and eCG cotreatment markedly reduces yields of viable oocytes. These data are consistent with the hypothesis that elevated FSH contributes to egg aneuploidy, declining fertility, and poor ovarian response and that ActRIIB:Fc can prevent egg aneuploidy, increase fertility, and improve ovarian response. Future studies will continue to examine whether ActRIIB:Fc works via FSH and/or other pathways and whether ActRIIB:Fc can prevent aneuploidy, increase fertility, and improve stimulation responsiveness in AMA women.

Yield of Echocardiogram and Predictors of Positive Yield in Pediatric Patients: A Study in an Urban, Community-Based Outpatient Pediatric Cardiology Clinic.

PubMed

Billa, Ramya Deepthi; Szpunar, Susan; Zeinali, Lida; Anne, Premchand

2018-01-01

The yield of outpatient echocardiograms varies based on the indication for the echocardiogram and the age of the patient. The purpose of this study was to determine the cumulative yield of outpatient echocardiograms by age group and reason for the test. A secondary aim was to determine the predictors of a positive echocardiogram in an outpatient cardiology clinic at a large community teaching hospital. We retrospectively reviewed the charts of 891 patients who had a first-time echocardiogram between 2011 and 2015. Positive yield was defined as echocardiographic findings that explained the reason for the echocardiogram. The overall positive yield was 8.2%. Children between birth and 3 months of age had the highest yield (34.2%), and children between 12 and 18 years of age had the lowest yield (1%). Patients with murmurs (18.1%) had the highest yield compared with patients with other signs or symptoms. By age group and reason, the highest yields were as follows: 0 to 3 months of age, murmur (39.2%); 4 to 11 months of age, >1 symptom (50%); and 1 to 5 years of age, shortness of breath (66.7%). Based on our study, the overall yield of echocardiograms in the outpatient pediatric setting is low. Age and symptoms should be considered before ordering an echocardiogram.

Surface Exposure Ages of Space-Weathered Grains from Asteroid 25143 Itokawa

NASA Technical Reports Server (NTRS)

Keller, L. P.; Berger, E. L.; Christoffersen, R.

2015-01-01

We use the observed effects of solar wind ion irradiation and the accumulation of solar flare particle tracks recorded in Itokawa grains to constrain the rates of space weathering and yield information about regolith dynamics. The track densities are consistent with exposure at mm depths for 104-105 years. The solar wind damaged rims form on a much faster timescale, <10(exp 3) years.

Exploring the optimal economic timing for crop tree release treatments in hardwoods: results from simulation

Treesearch

Chris B. LeDoux; Gary W. Miller

2008-01-01

In this study we used data from 16 Appalachian hardwood stands, a growth and yield computer simulation model, and stump-to-mill logging cost-estimating software to evaluate the optimal economic timing of crop tree release (CTR) treatments. The simulated CTR treatments consisted of one-time logging operations at stand age 11, 23, 31, or 36 years, with the residual...

Initiation of the Bukadaban Feng Normal Fault and Implications for the Topographic Evolution of Northern Tibet

NASA Astrophysics Data System (ADS)

Niemi, N. A.; Chang, H.; Li, L.; Molnar, P. H.

2017-12-01

The Bukadaban Feng massif in northern Tibet forms the footwall of an east-west trending graben that is kinematically linked to the Kunlun fault. Extension across this graben accommodates left-lateral slip on the Kunlun fault, as evidenced by the 2001 Kunlun earthquake rupture. New geochronologic and thermochronologic data from Bukadaban Feng provide insight into the evolution of this normal fault system. The Bukadaban Feng massif is composed of two plutonic units, an eastern unit of dacitic composition and a western unit of rhyolitic composition. Sixty-five LA-ICP-MS zircon U-Pb age determinations on the rhyolitic unit reveal a range of ages from 873 - 6.3 Ma. CA-TIMS U-Pb zircon geochronology on the nine youngest of these zircons yields an emplacement age of 6.8 Ma. Twenty-seven LA-ICP-MS zircon U-Pb ages on the dacite range from 208 to 7.9 Ma. No coherent population of young zircons was observed, and CA-TIMS analysis was not performed. Zircon (U-Th)/He analysis on the dacite and rhyolite yield ages of 3.9 and 5.0 Ma, respectively, while apatite (U-Th-Sm)/He thermochronology on 5 samples collected from both units along the trace of the normal fault yield ages ranging from 1.4 - 2.6 Ma. The emplacement ages and compositions of plutonic rocks at Bukadaban Feng are consistent with the eruptive timing and geochemistry of silicic volcanic rocks in the graben (Zhang et al., 2012). Silicic magmatism is often associated with the onset of crustal extension, and the combination of plutonism and correlative silicic volcanism provides an indirect constraint on the initiation of this graben at 7 Ma. The distinct zircon (U-Pb) and (U-Th)/He ages indicates that the rocks presently exposed at Bukadaban Feng were emplaced at ambient temperatures in excess of 180°C. The zircon and apatite thermochronologic data require exhumation at rates of 1-2 mm/yr since the late Miocene. A 7 Ma initiation age for the Bukadaban Feng normal fault is consistent with both published estimates of total offset across the Kunlun fault ( 70 km; Kidd and Molnar, 1988) and recent fault slip rates ( 10 mm/yr; van der Woerd et al., 2002). To the extent that the onset of extension and strike-slip faulting can be related to the attainment of high topography, these new data imply that northernmost Tibet may have reached maximum elevations as recently as the late Miocene.

Effects of C and Si on strain aging of strain-based API X60 pipeline steels

NASA Astrophysics Data System (ADS)

Sung, Hyo Kyung; Lee, Dong Ho; Lee, Sunghak; Lee, Byeong-Joo; Hong, Seung-Pyo; Kim, Young-Woon; Yoo, Jang Yong; Hwang, Byoungchul; Shin, Sang Yong

2017-05-01

Four types of strain-based API X60 pipeline steels were fabricated by varying the C and Si contents, and the effects of C and Si on strain aging were investigated. The 0.05 wt% C steels consisted mainly of polygonal ferrite (PF), whereas the 0.08 wt% C steels consisted of acicular ferrite (AF). The volume fraction of AF increased with increasing C content because C is an austenite stabilizer element. The volume fractions of bainitic ferrite (BF) of the 0.15 wt% Si steels were higher than those of the 0.25 wt% Si steels, whereas the volume fractions of the secondary phases were lower. From the tensile properties before and after the aging process of the strainbased API X60 pipeline steels, the yield strength increased and the uniform and total elongation decreased, which is the strain aging effect. The strain aging effect in the strain-based API X60 pipeline steels was minimized when the volume fraction of AF was increased and secondary phases were distributed uniformly. On the other hand, an excessively high C content formed fine precipitates, and the strain aging effect occurred because of the interactions among dislocations and fine precipitates.

A simple-rapid method to separate uranium, thorium, and protactinium for U-series age-dating of materials

PubMed Central

Knight, Andrew W.; Eitrheim, Eric S.; Nelson, Andrew W.; Nelson, Steven; Schultz, Michael K.

2017-01-01

Uranium-series dating techniques require the isolation of radionuclides in high yields and in fractions free of impurities. Within this context, we describe a novel-rapid method for the separation and purification of U, Th, and Pa. The method takes advantage of differences in the chemistry of U, Th, and Pa, utilizing a commercially-available extraction chromatographic resin (TEVA) and standard reagents. The elution behavior of U, Th, and Pa were optimized using liquid scintillation counting techniques and fractional purity was evaluated by alpha-spectrometry. The overall method was further assessed by isotope dilution alpha-spectrometry for the preliminary age determination of an ancient carbonate sample obtained from the Lake Bonneville site in western Utah (United States). Preliminary evaluations of the method produced elemental purity of greater than 99.99% and radiochemical recoveries exceeding 90% for U and Th and 85% for Pa. Excellent purity and yields (76% for U, 96% for Th and 55% for Pa) were also obtained for the analysis of the carbonate samples and the preliminary Pa and Th ages of about 39,000 years before present are consistent with 14C-derived age of the material. PMID:24681438

40Ar/(39)Ar dating of Chemeron Formation strata encompassing the site of hominid KNM-BC 1, Tugen Hills, Kenya.

PubMed

Deino, Alan L; Hill, Andrew

2002-01-01

A fossil hominid temporal bone (KNM-BC 1) from surface exposures at Baringo Paleontological Research Project site BPRP#2 in the Chemeron Formation outcropping in a tributary drainage of the Kapthurin River west of Lake Baringo, Kenya has been attributed to Homo sp. indet. K-feldspar phenocrysts from lapilli tuffs bracketing the inferred fossiliferous horizon yield single-crystal(40)Ar/(39)Ar ages of 2.456+/-0.006 and 2.393+/-0.013 Ma. These age determinations are supported by stratigraphically consistent ages on higher tuff horizons and from nearby sections. In addition, new(40)Ar/(39)Ar ages on tuffaceous units near the base and top of the formation along the Kapthurin River yield 3.19+/-0.03 and 1.60+/-0.05 Ma respectively. The base of the formation along the Kapthurin River is thus approximately 0.5 Ma younger than the uppermost Chemeron Formation strata exposed at Tabarin, 23 km to the north-northwest. The upper half of the formation along the Kapthurin River was deposited at an average rate of approximately 11 cm/ka, compared to 21-23 cm/ka at Tabarin. Copyright 2002 Academic Press.

Evaluating the impact of new observational constraints on P-S/IVOC emissions, multi-generation oxidation, and chamber wall losses on SOA modeling for Los Angeles, CA

NASA Astrophysics Data System (ADS)

Ma, Prettiny K.; Zhao, Yunliang; Robinson, Allen L.; Worton, David R.; Goldstein, Allen H.; Ortega, Amber M.; Jimenez, Jose L.; Zotter, Peter; Prévôt, André S. H.; Szidat, Sönke; Hayes, Patrick L.

2017-08-01

Secondary organic aerosol (SOA) is an important contributor to fine particulate matter (PM) mass in polluted regions, and its modeling remains poorly constrained. A box model is developed that uses recently published literature parameterizations and data sets to better constrain and evaluate the formation pathways and precursors of urban SOA during the CalNex 2010 campaign in Los Angeles. When using the measurements of intermediate-volatility organic compounds (IVOCs) reported in Zhao et al. (2014) and of semi-volatile organic compounds (SVOCs) reported in Worton et al. (2014) the model is biased high at longer photochemical ages, whereas at shorter photochemical ages it is biased low, if the yields for VOC oxidation are not updated. The parameterizations using an updated version of the yields, which takes into account the effect of gas-phase wall losses in environmental chambers, show model-measurement agreement at longer photochemical ages, even though some low bias at short photochemical ages still remains. Furthermore, the fossil and non-fossil carbon split of urban SOA simulated by the model is consistent with measurements at the Pasadena ground site. Multi-generation oxidation mechanisms are often employed in SOA models to increase the SOA yields derived from environmental chamber experiments in order to obtain better model-measurement agreement. However, there are many uncertainties associated with these aging mechanisms. Thus, SOA formation in the model is compared to data from an oxidation flow reactor (OFR) in order to constrain SOA formation at longer photochemical ages than observed in urban air. The model predicts similar SOA mass at short to moderate photochemical ages when the aging mechanisms or the updated version of the yields for VOC oxidation are implemented. The latter case has SOA formation rates that are more consistent with observations from the OFR though. Aging mechanisms may still play an important role in SOA chemistry, but the additional mass formed by functionalization reactions during aging would need to be offset by gas-phase fragmentation of SVOCs. All the model cases evaluated in this work show a large majority of the urban SOA (70-83 %) at Pasadena coming from the oxidation of primary SVOCs (P-SVOCs) and primary IVOCs (P-IVOCs). The importance of these two types of precursors is further supported by analyzing the percentage of SOA formed at long photochemical ages (1.5 days) as a function of the precursor rate constant. The P-SVOCs and P-IVOCs have rate constants that are similar to highly reactive VOCs that have been previously found to strongly correlate with SOA formation potential measured by the OFR. Finally, the volatility distribution of the total organic mass (gas and particle phase) in the model is compared against measurements. The total SVOC mass simulated is similar to the measurements, but there are important differences in the measured and modeled volatility distributions. A likely reason for the difference is the lack of particle-phase reactions in the model that can oligomerize and/or continue to oxidize organic compounds even after they partition to the particle phase.

Effect of prepubertal and postpubertal growth and age at first calving on production and reproduction traits during the first 3 lactations in Holstein dairy cattle.

PubMed

Krpálková, L; Cabrera, V E; Vacek, M; Stípková, M; Stádník, L; Crump, P

2014-05-01

The objective of this study was to evaluate the effect of body condition score (BCS), body weight (BW), average daily weight gain (ADG), and age at first calving (AFC) of Holstein heifers on production and reproduction parameters in the 3 subsequent lactations. The data set consisted of 780 Holstein heifers calved at 2 dairy farms in the Czech Republic from 2007 to 2011. Their BW and BCS were measured at monthly intervals during the rearing period (5 to 18 mo of age), and the milk production and reproduction data of the first 3 lactations were collected over an 8-yr period (2005 to 2012). The highest milk yield in the first lactation was found in the group with medium ADG (5 to 14 mo of age; 0.949 to 0.850 kg of ADG). The highest average milk yield over lifetime performance was detected in heifers with the highest total ADG (≥ 0.950 kg/d). The difference in milk yield between the evaluated groups of highest ADG (in total and postpubertal growth ≥ 0.950 kg/d and in prepubertal growth ≥ 0.970 kg/d) and the lowest ADG (≤ 0.849 kg/d) was approximately 1,000 kg/305 d per cow. The highest milk yield in the first lactation was found in the group with the highest AFC ≥ 751 d, for which fat and protein content in the milk was not reduced. Postpubertal growth (11 to 14 mo of age) had the greatest effect on AFC. The group with lowest AFC ≤ 699 d showed a negative effect on milk yield but only in the first 100 d of the first parity. The highest ADG was detrimental to reproduction parameters in the first lactation. The highest BW at 14 mo (≥ 420 kg) led to lower AFC. Groups according to BCS at 14 mo showed no differences in AFC or milk yield in the first lactation or lifetime average production per lactation. We concluded that low AFC ≤ 699 d did not show a negative effect on subsequent production and reproduction parameters. Therefore, a shorter rearing period is recommended for dairy herds with suitable management. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

SHRIMP-RG U-Pb isotopic systematics of zircon from the Angel Lake orthogneiss, East Humboldt Range, Nevada: Is this really archean crust?

USGS Publications Warehouse

Premo, Wayne R.; Castineiras, Pedro; Wooden, Joseph L.

2008-01-01

New SHRIMP-RG (sensitive high-resolution ion microprobe-reverse geometry) data confirm the existence of Archean components within zircon grains of a sample from the orthogneiss of Angel Lake, Nevada, United States, previously interpreted as a nappe of Archean crust. However, the combined evidence strongly suggests that this orthogneiss is a highly deformed, Late Cretaceous monzogranite derived from melting of a sedimentary source dominated by Archean detritus. Zircon grains from the same sample used previously for isotope dilution-thermal ionization mass spectrometry (ID-TIMS) isotopic work were analyzed using the SHRIMP-RG to better define the age and origin of the orthogneiss. Prior to analysis, imaging revealed a morphological variability and intragrain, polyphase nature of the zircon population. The SHRIMP-RG yielded 207Pb/206Pb ages between ca. 2430 and 2580 Ma (a best-fit mean 207Pb/206Pb age of 2531 ± 19 Ma; 95% confidence) from mostly rounded to subrounded zircons and zircon components (cores). In addition, several analyses from rounded to subrounded cores or grains yielded discordant 207Pb/206Pb ages between ca. 1460 and ca. 2170 Ma, consistent with known regional magmatic events. All cores of Proterozoic to latest Archean age were encased within clear, typically low Th/U (206Pb/238U ages between 72 and 91 Ma, consistent with magmatic ages from Lamoille Canyon to the south. An age of ca. 90 Ma is suggested, the younger 206Pb/238U ages resulting from Pb loss. The Cretaceous and Precambrian zircon components also have distinct trace element characteristics, indicating that these age groups are not related to the same igneous source. These results support recent geophysical interpretations and negate the contention that the Archean-Proterozoic boundary extends into the central Great Basin area. They further suggest that the world-class gold deposits along the Carlin Trend are not underlain by Archean cratonal crust, but rather by the Proterozoic Mojave province and Neoproterozoic and Paleozoic metasedimentary sequences dominated by detritus derived from Late Archean sources rather than Proterozoic sources, as is evident farther to the south in the Ruby Mountains.

Psychometric properties of the defense style questionnaire (DSQ-40) in adolescents.

PubMed

Ruuttu, Titta; Pelkonen, Mirjami; Holi, Matti; Karlsson, Linnea; Kiviruusu, Olli; Heilä, Hannele; Tuisku, Virpi; Tuulio-Henriksson, Annamari; Marttunen, Mauri

2006-02-01

This study examined the psychometric properties of the Defense Style Questionnaire (DSQ-40) in adolescents. Internal consistency, factor structure, and discriminant and concurrent validity of the DSQ-40 were studied in 211 adolescent psychiatric outpatients aged 13 to 19 years and 199 age-matched and sex-matched controls. Principal components analysis yielded four internally consistent components: mature, neurotic, image-distorting, and immature defense styles. The outpatients reported more immature, image-distorting, and neurotic styles and less mature style than did the controls, suggesting adequate discriminant validity. As a demonstration of convergent and concurrent validity, the severity of psychiatric symptoms assessed by the General Health Questionnaire and psychosocial adjustment assessed by the Global Assessment of Functioning Scale correlated theoretically meaningfully with the different defense styles. The DSQ-40 appears to be a reliable and valid instrument for adolescents.

Secondary organic aerosol and ozone formation from photo-oxidation of unburned diesel fuel in a surrogate atmospheric environment

NASA Astrophysics Data System (ADS)

Li, Weihua; Cocker, David R.

2018-07-01

Diesel fuel is a complex mixture of intermediate volatility organic compounds (IVOCs). Previous studies focused on secondary organic aerosol (SOA) and ozone formation from photo-oxidation of organic vapor from diesel exhaust and their components such as aromatics and heavy alkanes. However, there are few studies on atmospheric behavior of unburnt diesel. Therefore, in this study, ten unburnt #2 commercial diesel samples and one FACE9A research diesel fuel were photo-oxidized in the University of California Riverside, College of Engineering-Center for Environmental Research & Technology dual environmental chambers to investigate their SOA and ozone production potential. Photochemical aging rapidly produced significant SOA (yield ∼20.3-37.7%) in the presence of a surrogate reactive organic gas (ROG) mixture used to mimic urban atmospheric reactivity. SOA yields were consistent with n-Heptadecane yields under similar conditions. Doubling NOx concentrations within relevant urban concentration levels enhanced SOA formation by 33% and ozone formation by 48%. SOA formation in this study was approximately fourteen times higher than previously reported for very high NOx conditions. An SOA experiment designed to mimic the previous work achieved similar yields to the earlier work. SOA formed under urban relevant NOx concentrations were consistent with semi-volatile-oxygenated organic aerosol (SV-OOA) and underwent little further chemical processing once produced.

Identification of last interglacial deposits in eastern Beringia: a cautionary note from the Palisades, interior Alaska

USGS Publications Warehouse

Reyes, Alberto V.; Zazula, Grant D.; Kuzmina, Svetlana; Ager, Thomas A.; Froese, Duane G.

2011-01-01

Last interglacial sediments in unglaciated Alaska and Yukon (eastern Beringia) are commonly identified by palaeoecological indicators and stratigraphic position ~2-5m above the regionally prominent Old Crow tephra (124 + or - 10ka). We demonstrate that this approach can yield erroneous age assignments using data from a new exposure at the Palisades, a site in interior Alaska with numerous exposures of last interglacial sediments. Tephrochronology, stratigraphy, plant macrofossils, pollen and fossil insects from a prominent wood-rich organic silt unit are all consistent with a last interglacial age assignment. However, six 14C dates on plant and insect macrofossils from the organic silt range from non-finite to 4.0 14C ka BP, indicating that the organic silt instead represents a Holocene deposit with a mixed-age assemblage of organic material. In contrast, wood samples from presumed last interglacial organic-rich sediments elsewhere at the Palisades, in a similar stratigraphic position with respect to Old Crow tephra, yield non-finite 14C ages. Given that local permafrost thaw since the last interglaciation may facilitate reworking of older sediments into new stratigraphic positions, minimum constraining ages based on 14C dating or other methods should supplement age assignments for last interglacial sediments in eastern Beringia that are based on palaeoecology and stratigraphic association with Old Crow tephra.

Modeled ground water age distributions

USGS Publications Warehouse

Woolfenden, Linda R.; Ginn, Timothy R.

2009-01-01

The age of ground water in any given sample is a distributed quantity representing distributed provenance (in space and time) of the water. Conventional analysis of tracers such as unstable isotopes or anthropogenic chemical species gives discrete or binary measures of the presence of water of a given age. Modeled ground water age distributions provide a continuous measure of contributions from different recharge sources to aquifers. A numerical solution of the ground water age equation of Ginn (1999) was tested both on a hypothetical simplified one-dimensional flow system and under real world conditions. Results from these simulations yield the first continuous distributions of ground water age using this model. Complete age distributions as a function of one and two space dimensions were obtained from both numerical experiments. Simulations in the test problem produced mean ages that were consistent with the expected value at the end of the model domain for all dispersivity values tested, although the mean ages for the two highest dispersivity values deviated slightly from the expected value. Mean ages in the dispersionless case also were consistent with the expected mean ages throughout the physical model domain. Simulations under real world conditions for three dispersivity values resulted in decreasing mean age with increasing dispersivity. This likely is a consequence of an edge effect. However, simulations for all three dispersivity values tested were mass balanced and stable demonstrating that the solution of the ground water age equation can provide estimates of water mass density distributions over age under real world conditions.

Epidemiological evidence for an association between use of wireless phones and tumor diseases.

PubMed

Hardell, Lennart; Carlberg, Michael; Hansson Mild, Kjell

2009-08-01

During recent years there has been increasing public concern on potential cancer risks from microwave emissions from wireless phones. We evaluated the scientific evidence for long-term mobile phone use and the association with certain tumors in case-control studies, mostly from the Hardell group in Sweden and the Interphone study group. Regarding brain tumors the meta-analysis yielded for glioma odds ratio (OR)=1.0, 95% confidence interval (CI)=0.9-1.1. OR increased to 1.3, 95% CI=1.1-1.6 with 10 year latency period, with highest risk for ipsilateral exposure (same side as the tumor localisation), OR=1.9, 95% CI=1.4-2.4, lower for contralateral exposure (opposite side) OR=1.2, 95% CI=0.9-1.7. Regarding acoustic neuroma OR=1.0, 95% CI=0.8-1.1 was calculated increasing to OR=1.3, 95% CI=0.97-1.9 with 10 year latency period. For ipsilateral exposure OR=1.6, 95% CI=1.1-2.4, and for contralateral exposure OR=1.2, 95% CI=0.8-1.9 were found. Regarding meningioma no consistent pattern of an increased risk was found. Concerning age, highest risk was found in the age group <20 years at time of first use of wireless phones in the studies from the Hardell group. For salivary gland tumors, non-Hodgkin lymphoma and testicular cancer no consistent pattern of an association with use of wireless phones was found. One study on uveal melanoma yielded for probable/certain mobile phone use OR=4.2, 95% CI=1.2-14.5. One study on intratemporal facial nerve tumor was not possible to evaluate due to methodological shortcomings. In summary our review yielded a consistent pattern of an increased risk for glioma and acoustic neuroma after >10 year mobile phone use. We conclude that current standard for exposure to microwaves during mobile phone use is not safe for long-term exposure and needs to be revised.

Paleocene and Maastrichtian calcareous nannofossils from clasts in Pleistocene glaciomarine muds from the northern James Ross Basin, western Weddell Sea, Antarctica

USGS Publications Warehouse

Kulhanek, D.K.

2007-01-01

Site NBP0602A-9, drilled during the SHALDRIL II cruise of the RV/IB Nathaniel B. Palmer, includes two holes located in the northern James Ross Basin in the western Weddell Sea, very close to the eastern margin of the Antarctic Peninsula. Sediment from both holes consists of very dark grey, pebbly, sandy mud, grading to very dark greenish grey, pebbly, silty mud in the lower 2.5 m of the second hole. In addition to abundant pebbles found throughout the cores, both holes contain numerous sedimentary clasts. Biostratigraphic analysis of diatom assemblages from the glaciomarine muds yields rare to few, poorly preserved diatoms. The mixed assemblage consists mostly of extant species, but also includes reworked taxa that range to the Miocene. The absence of Rouxia spp., however, suggests the sediment is late Pleistocene in age. The sedimentary clasts, on the other hand, are nearly barren of diatoms, but contain rare, moderately to well-preserved calcareous nannofossils. The clasts contain three distinct assemblages. Two clasts are assigned an early Maastrichtian age based on the presence of Biscutum magnum and Nephrolithus corystus, while one clast yields a late Maastrichtian age based on the presence of Nephrolithus frequens. These samples also contain other characteristic Late Cretaceous species, including Biscutum notaculum, Cribrosphaerella daniae, Eiffellithus gorkae, Kamptnerius magnificus, and Prediscosphaera bukryi. Two samples yield an early Paleocene assemblage dominated by Hornibrookina teuriensis. The Maastrichtian assemblages are similar to those found in the López de Bertodano Formation on Seymour and Snow Hill Islands, making it the likely source area for the Cretaceous clast material. Although no calcareous nannofossils have been reported from Paleocene formations on these islands, the occurrence of calcareous foraminifers suggests other calcareous plankton may be present; thus the Paleocene clasts likely also originated from the Seymour Island area.

The Quaternary impact record from the Pampas, Argentina

NASA Astrophysics Data System (ADS)

Schultz, Peter H.; Zárate, Marcelo; Hames, Bill; Koeberl, Christian; Bunch, Theodore; Storzer, Dieter; Renne, Paul; Wittke, James

2004-03-01

Loess-like deposits cover much of central Argentina and preserve a rich record of impacts since the late Miocene. The present contribution focuses on two localities containing Quaternary impact glasses: along the coastal sequences near Centinela del Mar (CdM) and from near Rio Cuarto (RC). These highly vesicular glasses contain clear evidence for an impact origin including temperatures sufficient to melt most mineral constituents (1700°C) and to leave unique quench products such as β-cristobolite. The CdM glasses occur within a relatively narrow horizon just below a marine transgression expressed by a series of coastal paleo-dunes and systematic changes in the underlying sediments. High-resolution 40Ar/39Ar dating methods yielded an age of 445±21 ka (2σ). Glasses were also recovered from scattered occurrences lower in the section but were dated to 230±40 ka. This inconsistency between stratigraphic and radiometric age is most likely related to a nearby outcrop of glass that had been exposed and locally re-deposited in coastal lagoons during the last marine transgression at 125 ka. Sediments containing the original impact glass layer are now missing due to an unconformity, perhaps related to subsequent marine transgressions after the impact (410 ka and 340 ka) and hiatuses in deposition. Two different types of impact glasses from RC yield two distinct dates. High-resolution 40Ar/39Ar dating of fresher-appearing glasses (well-preserved tachylitic sheen) indicates an age of 6±2 ka (2σ). Independent fission track analyses yielded a similar age of 2.3±1.6 ka (2σ). More weathered glasses, however, gave significantly older ages of 114±26 ka (2σ). Consequently, materials from two separate Quaternary impacts have been recovered at Rio Cuarto. The younger glasses are consistent with previously reported carbon dates for materials on the floor of one of the large elongate structures. The depths of excavation for the RC and CdM impacts are very different. While the RC glasses are largely derived from near-surface materials, the CdM glasses from the upper level contain added components consistent with Miocene marine evaporites at a depth of about 400-500 m (e.g., high CaO and P2O5). The CdM glasses also incorporated older loess-like sediments from depth based on the geochemistry. Several ratios of key trace and rare earth elements of sediments of different ages from the Miocene to the Holocene indicate a systematic compositional change through time. Such changes calibrate the observed differences in glass composition from their host sediments and further indicate incorporation of materials from depth. Consequently, the Argentine loess-like sediments preserve evidence for at least four separate Quaternary impacts. Based on foreign components in the glasses, the CdM impact very likely produced a crater (now buried or eroded) once as large as 6 km in diameter. The younger RC glasses, however, are consistent with shallower excavation consistent with an oblique impact.

Development of parmesan cheese production from local cow milk

NASA Astrophysics Data System (ADS)

Aliwarga, Lienda; Christianti, Elisabeth Novi; Lazarus, Chrisella

2017-05-01

Parmesan cheese is one of the dairy products which is used in various foods, such as pasta, bakery product, and pizza. It has a hard texture due to aging process for at least two years. Long aging period inhibited the production of parmesan cheese while consumer demands were increasing gradually. This research was conducted to figure out the effect of starter culture and rennet dose to the production of parmesan cheese. This research consists of (1) pasteurization of 1,500 ml milk at 73°C; and (2) main cheese making process that comprised of fermentation process and the addition of rennet. In latter stage, milk was converted into curd. Variations were made for the dose of bacteria culture and rennet. Both variables correlated to the fermentation time and characteristics of the produced cheese. The analysis of the produced cheese during testing stage included measured protein and cheese yield, whey pH, water activity, and moisture content. Moreover, an organoleptic test was done in a qualitative manner. The results showed that the dose of bacteria culture has a significant effect to the fermentation time, protein yield, and cheese yield. Meanwhile, rennet dose significantly affected cheese yield, pH of whey, and water activity. The highest protein yield (93.1%) was obtained at 0.6 ml of culture and 0.5 ml of rennet while the maximum cheese yield (6.81%) was achieved at 0.4 ml of culture and 0.1 ml of rennet. The water activity of produced cheeses was lower compared to the water activity of common parmesan cheese (ca. 0.6). For the organoleptic test, 0.4 ml of bacterial culture and 0.5 ml of rennet produced the most preferred cheese flavor compared to other variations.

Dynamics and structure of an aging binary colloidal glass

NASA Astrophysics Data System (ADS)

Lynch, Jennifer M.; Cianci, Gianguido C.; Weeks, Eric R.

2008-09-01

We study aging in a colloidal suspension consisting of micron-sized particles in a liquid. This system is made glassy by increasing the particle concentration. We observe samples composed of particles of two sizes, with a size ratio of 1:2.1 and a volume fraction ratio 1:6, using fast laser scanning confocal microscopy. This technique yields real-time, three-dimensional movies deep inside the colloidal glass. Specifically, we look at how the size, motion, and structural organization of the particles relate to the overall aging of the glass. Particles move in spatially heterogeneous cooperative groups. These mobile regions tend to be richer in small particles, and these small particles facilitate the motion of nearby particles of both sizes.

Resolving the age of Wilson Creek Formation tephras and the Mono Lake excursion using high-resolution SIMS dating of allanite and zircon rims

NASA Astrophysics Data System (ADS)

Vazquez, J. A.; Lidzbarski, M. I.

2012-12-01

Sediments of the Wilson Creek Formation surrounding Mono Lake preserve a high-resolution archive of glacial and pluvial responses along the eastern Sierra Nevada due to late Pleistocene climate change. An absolute chronology for the Wilson Creek stratigraphy is critical for correlating the paleoclimate record to other archives in the western U.S. and the North Atlantic region. However, multiple attempts to date the Wilson Creek stratigraphy using carbonates and interbedded rhyolitic tephras yield discordant 14C and 40Ar/39Ar results due to open-system effects, carbon reservoir uncertainties, as well as abundant xenocrysts entrained during eruption. Ion microprobe (SIMS) 238U-230Th dating of the final increments of crystallization recorded by allanite and zircon autocrysts from juvenile pyroclasts yields ages that effectively date eruption of key tephra beds and resolve age uncertainties about the Wilson Creek stratigraphy. To date the final several micrometers of crystal growth, individual allanite and zircon crystals were embedded in soft indium to allow sampling of unpolished rims. Isochron ages derived from rims on coexisting allanite and zircon (± glass) from hand-selected pumiceous pyroclasts delimit the timing of Wilson Creek sedimentation between Ashes 7 and 19 (numbering of Lajoie, 1968) to the interval between ca. 27 to ca. 62 ka. The interiors of individual allanite and zircon crystals sectioned in standard SIMS mounts yield model 238U-230Th ages that are mostly <10 k.y. older than their corresponding rim age, suggesting a relatively brief interval of allanite + zircon crystallization before eruption. A minority of allanite and zircon crystals yield rim and interior model ages of ca. 90-100 ka, and are likely to be antecrysts recycled from relatively early Mono Craters volcanism and/or intrusions. Tephra (Ash 15) erupted during the geomagnetic excursion originally designated the Mono Lake excursion yields a rim isochron age of ca. 41 ka indicating that the recorded event is instead the Laschamp excursion. The results are consistent with a depositional chronology from correlation of relative paleointensity (Zimmerman et al., 2006) that indicates quasi-synchronous glacial and hydrologic responses in the Sierra Nevada and Mono Basin to climate change, with intervals of lake filling and glacial-snowpack melting that are in phase with peaks in spring insolation. Moreover, the results demonstrate that high-spatial resolution SIMS dating of accessory mineral rims is an alternative and promising approach for resolving the depositional ages of silicic tephras containing minerals that crystallized over protracted intervals or that are plagued by incorporation of xenocrysts and/or antecrysts. References: Lajoie, K., 1968, PhD Dissertation, UC Berkeley; Zimmerman et al., 2006, EPSL 252: 94-106.

A multiple-approach radiometric age estimate for the Rotoiti and Earthquake Flat eruptions, New Zealand, with implications for the MIS 4/3 boundary

USGS Publications Warehouse

Wilson, C.J.N.; Rhoades, D.A.; Lanphere, M.A.; Calvert, A.T.; Houghton, Bruce F.; Weaver, S.D.; Cole, J.W.

2007-01-01

Pyroclastic fall deposits of the paired Rotoiti and Earthquake Flat eruptions from the Taupo Volcanic Zone (New Zealand) combine to form a widespread isochronous horizon over much of northern New Zealand and the southwest Pacific. This horizon is important for correlating climatic and environmental changes during the Last Glacial period, but has been the subject of numerous disparate age estimates between 35.1??2.8 and 71??6 ka (all errors are 1 s.d.), obtained by a variety of techniques. A potassium-argon (K-Ar) age of 64??4 ka was previously determined on bracketing lavas at Mayor Island volcano, offshore from the Taupo Volcanic Zone. We present a new, more-precise 40Ar/39Ar age determination on a lava flow on Mayor Island, that shortly post-dates the Rotoiti/Earthquake Flat fall deposits, of 58.5??1.1 ka. This value, coupled with existing ages from underlying lavas, yield a new estimate for the age of the combined eruptions of 61.0??1.4 ka, which is consistent with U-Th disequilibrium model-age data for zircons from the Rotoiti deposits. Direct 40Ar/39Ar age determinations of plagioclase and biotite from the Rotoiti and Earthquake Flat eruption products yield variable values between 49.6??2.8 and 125.3??10.0 ka, with the scatter attributed to low radiogenic Ar yields, and/or alteration, and/or inheritance of xenocrystic material with inherited Ar. Rotoiti/Earthquake Flat fall deposits occur in New Zealand in association with palynological indicators of mild climate, attributed to Marine Isotope Stage (MIS) 3 and thus used to suggest an age that is post-59 ka. The natures of the criteria used to define the MIS 4/3 boundary in the Northern and Southern hemispheres, however, imply that the new 61 ka age for the Rotoiti/Earthquake Flat eruption deposits will provide the inverse, namely, a more accurate isochronous marker for correlating diverse changes across the MIS 4/3 boundary in the southwest Pacific. ?? 2007 Elsevier Ltd. All rights reserved.

A simple-rapid method to separate uranium, thorium, and protactinium for U-series age-dating of materials.

PubMed

Knight, Andrew W; Eitrheim, Eric S; Nelson, Andrew W; Nelson, Steven; Schultz, Michael K

2014-08-01

Uranium-series dating techniques require the isolation of radionuclides in high yields and in fractions free of impurities. Within this context, we describe a novel-rapid method for the separation and purification of U, Th, and Pa. The method takes advantage of differences in the chemistry of U, Th, and Pa, utilizing a commercially-available extraction chromatographic resin (TEVA) and standard reagents. The elution behavior of U, Th, and Pa were optimized using liquid scintillation counting techniques and fractional purity was evaluated by alpha-spectrometry. The overall method was further assessed by isotope dilution alpha-spectrometry for the preliminary age determination of an ancient carbonate sample obtained from the Lake Bonneville site in western Utah (United States). Preliminary evaluations of the method produced elemental purity of greater than 99.99% and radiochemical recoveries exceeding 90% for U and Th and 85% for Pa. Excellent purity and yields (76% for U, 96% for Th and 55% for Pa) were also obtained for the analysis of the carbonate samples and the preliminary Pa and Th ages of about 39,000 years before present are consistent with (14)C-derived age of the material. Copyright © 2014 Elsevier Ltd. All rights reserved.

Geochronology of the Baye Mn oxide deposit, southern Yunnan Plateau: Implications for the late Miocene to Pleistocene paleoclimatic conditions and topographic evolution

NASA Astrophysics Data System (ADS)

Deng, Xiao-Dong; Li, Jian-Wei; Vasconcelos, Paulo M.; Cohen, Benjamin E.; Kusky, Timothy M.

2014-08-01

40Ar/39Ar laser incremental heating analyses of supergene K-Mn oxides from weathering profiles at the Baye Mn deposit, southern Yunnan Plateau, SW China, were carried out to place constraints on the timing of weathering and derive insights into local paleoclimatic and landscape evolution. Weathering profiles in the Baye Mn mine are dominated by 20-30 m thick saprolites, which are locally covered by unconsolidated alluvial deposits. We analyzed 70 grains from 35 hand samples collected from four sites located at distinct elevations. In most cases, different grains from the same hand sample and different samples from the same site have reproducible 40Ar/39Ar plateau ages. The plateau ages of individual grains are also consistent with the respective isochron, integrated, and ideogram ages. This age consistency attests to the reliability of the geochronological results as numerical constraints on the formation and evolution of these weathering profiles. Sixty-four grains from 32 hand samples collected from weathering profiles at four sites (A to D) yield well-defined plateau or pseudoplateau ages ranging from 2.98 ± 0.07 to <0.16 Ma (2σ). The age results show that Mn oxides become progressively younger towards lower elevations: samples collected from the highest elevation site (∼1855 m a.s.l.) have the oldest ages at 2.98 ± 0.07 to 2.83 ± 0.13 Ma; samples from intermediate elevations (1821 to 1815 m a.s.l.) yield ages ranging from 2.91 ± 0.10 to 2.08 ± 0.11 Ma; and those from the lowest sites (1768 to 1753 m a.s.l.) are younger than 1.25 ± 0.08 Ma. The age versus elevation relationship indicates fast downward propagation of weathering front since the late Pliocene, and permits estimating the weathering rates at 3.3 ± 3.8, 6.6 ± 1.2, and 11.1 ± 1.9 m Myr-1 during the time periods of 2.98-2.83, 2.91-2.08, and 1.25 to <0.16 Ma, respectively. The average river incision rates estimated from the surface exposed ages range from 235 ± 10 to 416 ± 19 m Myr-1 during the past 3 million years. The incision rate calculated from minimum exposed ages at sites B-D is 33 ± 2 m Myr-1 for the time period of 2.91-1.25 Ma, which is consistent with the slow incision of streams on the ridges over the Yunnan Plateau since the early Pleistocene. Three Mn oxide pebbles contained in the alluvial deposits overlying the saprolite-dominated weathering profiles at the two highest sites provided additional information on the timing of weathering. Four grains from two pebbles yield plateau ages of 6.32 ± 0.19 to 5.27 ± 0.10 Ma, whereas the other two grains from the third pebble indicate the minimum formation ages of 8.2 ± 0.4 and 9.3 ± 0.3 Ma. These ages confirm the existence of older weathering profiles, now dismantled, in the region. Manganese oxide 40Ar/39Ar ages of the Baye deposit, when combined with results from other localities, indicate that lateritic weathering and supergene Mn enrichment and, by inference, warm and humid climates conducive to intense weathering have prevailed over the Plateau since the middle to late Miocene. The climatic conditions inferred from the weathering geochronology are consistent with multiple independent marine and terrestrial sedimentary and paleontological records, confirming that supergene Mn oxides can be used as a useful proxy for past climate. Age clusters of Mn oxides at 2.9-2.4, 1.2-0.8, and 0.6-0.4 Ma are broadly coincident with and thus likely reflect intensification events of the Indian Summer Monsoon that brings moisture and abundant precipitation to the Yunnan Plateau. These clusters also coincide with the periods of significant surface uplift in the Yunnan Plateau, demonstrating a causal link between topographic evolution, plateau uplift, and intensification of the monsoonal climate.

Sm-Nd dating of the giant Sullivan Pb-Zn-Ag deposit, British Columbia

USGS Publications Warehouse

Jiang, Shao-Yong; Slack, John F.; Palmer, Martin R.

2000-01-01

We report here Sm and Nd isotope data for hydrothermal tourmalinites and sulfide ores from the giant Sullivan Pb-Zn-Ag deposit, which occurs in the lower part of the Mesoproterozoic Purcell (Belt) Supergroup. Whole-rock samples of quartz-tourmaline tourmalinite from the footwall alteration pipe yield a Sm-Nd isochron age of 1470 ± 59 Ma, recording synsedimentary B metasomatism of clastic sediments during early evolution of the Sullivan hydrothermal system. Data for variably altered (chloritized and/or albitized) tourmalinites from the hanging wall of the deposit, which are believed to have formed originally ca. 1470 Ma, define a younger 1076 ± 77 Ma isochron because of resetting of Sm and Nd isotopes during Grenvillian metamorphism. HCl leachates of bedded Pb-Zn ore yield a Sm-Nd isochron age of 1451 ± 46 Ma, which is consistent with syngenetic-exhalative mineralization ca. 1470 Ma; this age could also reflect a slightly younger, epigenetic hydrothermal event. Results obtained for the Sullivan deposit indicate that the Sm-Nd geochronometer has the potential to directly date mineralization and alteration in stratabound sulfide deposits that are not amenable to dating by other isotope methods.

Paleomagnetism and geochronology of an Early Proterozoic quartz diorite in the southern Wind River Range, Wyoming, USA

USGS Publications Warehouse

Harlan, S.S.; Geisman, J.W.; Premo, W.R.

2003-01-01

We present geochronologic and paleomagnetic data from a north-trending quartz diorite intrusion that cuts Archean metasedimentary and metaigneous rocks of the South Pass Greenstone Belt of the Wyoming craton. The quartz diorite was previously thought to be either Archean or Early Proterozoic (?) in age and is cut by north and northeast-trending Proterozoic diabase dikes of uncertain age, for which we also report paleomagnetic data. New U-Pb analyses of baddeleyite and zircon from the quartz diorite yield a concordia upper intercept age of 2170 ?? 8 Ma (95% confidence). An 40Ar/39Ar amphibole date from the same sample yields a similar apparent age of about 2124 ?? 30 Ma (2??), thus confirming that the intrusion is Early Proterozoic in age and that it has probably not been thermally disturbed since emplacement. A magmatic event at ca. 2.17 Ga has not previously been documented in the Wyoming craton. The quartz diorite and one of the crosscutting diabase dikes yield essentially identical, well-defined characteristic remanent magnetizations. Results from eight sites in the quartz diorite yield an in situ mean direction of north declination and moderate to steep positive inclination (Dec.=355??, Inc.=65??, k=145, ??95=5??) with a paleomagnetic pole at 84??N, 215??E (??m=6??, ??p=7??). Data from other diabase dike sites are inconsistent with the quartz diorite results, but the importance of these results is uncertain because the age of the dikes is not well known. Interpretation of the quartz diorite remanent magnetization is problematic. The in situ direction is similar to expected directions for magnetizations of Late Cretaceous/early Tertiary age. However, there is no compelling evidence to suggest that these rocks were remagnetized during the late Mesozoic or Cenozoic. Assuming this magnetization to be primary, then the in situ paleomagnetic pole is strongly discordant with poles of 2167, 2214, and 2217 Ma from the Canadian Shield, and is consistent with proposed separation of the Wyoming Craton and Laurentia prior to about 1.8 Ga. Correcting the quartz diorite pole for the possible effects of Laramide-age tilting of the Wind River Range, based on the attitude of nearby overlying Cambrian Flathead Sandstone (dip=20??, N20??E), gives a tilt corrected pole of 75??N, 58??E (??m=4??, ??p=6??), which is also discordant with respect to time-equivalent poles from the Superior Province. Reconstruction of the Superior and Wyoming Province using a rotation similar to that proposed by Roscoe and Card [Can. J. Earth Sci. 46(1993)2475] is problematic, but reconstruction of the Superior and Wyoming Provinces based on restoring them to their correct paleolatitude and orientation using a closest approach fit indicates that the two cratons could have been adjacent at about 2.17 Ga prior to rifting at about 2.15 Ga. The paleomagnetic data presented are consistent with the hypothesis that the Huronian and Snowy Pass Supergroups could have evolved as part of a single epicratonic sedimentary basin during the Early Proterozoic. ?? 2002 Elsevier Science B.V. All rights reserved.

Accessing the application of in situ cosmogenic 14C to surface exposure dating of amorphous SiO2

NASA Astrophysics Data System (ADS)

Cesta, J. M.; Goehring, B. M.; Ward, D. J.

2017-12-01

We assess the feasibility and utility of in situ cosmogenic 14C as a geochronometer for landforms composed of amorphous SiO2 through the comparison of 14C surface exposure ages to independently determined eruption ages on Obsidian Dome, California. Landforms composed of amorphous SiO2 phases are difficult to date by conventional cosmogenic nuclide methods due to several complications that may arise (e.g., inability to remove meteoric contamination). The onset of an increased understanding of production rates and analytical measurement of in situ 14C in SiO2 provides an opportunity to address this limitation. Obsidian Dome is a 600-year-old phreatomagmatic dome of the Mono-Inyo Craters located in Inyo County, California, and consists of vesicular pumice, obsidian, and rhyolite. Exposure ages from eight obsidian and banded pumice and obsidian surface samples range from 3947 ± 678 to 914 ± 134 years, all significantly older than the accepted radiocarbon age of 650-550 years. δ13C values for the samples range between +2.65‰ and +1.34‰ and show a negative correlation with CO2 yield. The `too old' exposure ages coupled with this negative correlation between δ13C and CO2 yield suggests the incorporation of an atmospheric component of 14C. Measurement of 14C concentrations in shielded, subsurface samples will assist in isolating the atmospheric 14C component and aid in correcting the surface exposure ages.

Relationships of concentrations of certain blood constituents with milk yield and age of cows in dairy herds.

PubMed

Kitchenham, B A; Rowlands, G J; Shorbagi, H

1975-05-01

Regression analyses were performed on data from 48 Compton metabolic profile tests relating the concentrations of certain constituents in the blood of dairy cows to their milk yield, age and stage of lactation. The common partial regression coefficients for milk yield, age and stage of lactation were estimated for each blood constituent. The relationships of greatest statistical significance were between the concentrations of inorganic phosphate and globulin and age, and the concentration of albumin and milk yield.

Including Deposition Rate in Models of Cosmogenic Nuclide Accumulation in Fluvial Sediments to Improve Terrace Abandonment Ages

NASA Astrophysics Data System (ADS)

Norton, K. P.; Wang, N.; Van Dissen, R. J.; Little, T.

2017-12-01

Fluvial sediments are archives of the erosional, transport, and depositional processes occurring in the catchment. Terraces become robust markers for geomorphic analysis if their time of abandonment can be determined. Methods such as OSL can determine burial ages for fine grained sediments within the terrace fill but may not be directly related to the terrace abandonment age. Cosmogenic nuclides can be used to determine exposure ages for geologically young terraces but the surface being dated may have been subsequently eroded and the material itself may have been deposited with an inherited nuclide concentration. To deal with this problem, many researchers collect multiple samples with depth to model the depth-dependent nuclide concentration to help constrain inheritance and post-depositional erosion. It is often, however, assumed that the entire sediment pile accumulated instantaneously. In this submission, we present the results of a depth profile model that incorporates sediment accumulation rate to improve terrace age estimates. We test this model on fault-offset river terraces near Kaikoura, New Zealand. We measured depth profiles of OSL ages and cosmogenic nuclide concentrations of two late Quaternary terraces that are offset by up to 800 m across the Kekerengu Fault. OSL ages and dated tephras in the overlying loess provide minimum age constraints for both terraces while OSL ages of fine-grained sediments within the fill provide depositional ages. The predicted sedimentation rates for the terraces are as high as 0.5m/yr, consistent with geologically instantaneous deposition. Modelled abandonment ages from cosmogenic nuclides for the terraces are consistent with OSL and tephra constraints at 9.7 +/- 3.8 ka and 30.4 +/- 2.1 ka, respectively. These terrace abandonment ages yield dextral slip rates of 18.5-20.5 mm/yr and 25-28 mm/yr, respectively, consistent with the rapid slip rate on the adjacent Hope Fault.

Timescales for nitrate contamination of spring waters, northern Florida, USA

USGS Publications Warehouse

Katz, B.G.; Böhlke, J.K.; Hornsby, H.D.

2001-01-01

Residence times of groundwater, discharging from springs in the middle Suwannee River Basin, were estimated using chlorofluorocarbons (CFCs), tritium (3H), and tritium/helium-3 (3H/3He) age-dating methods to assess the chronology of nitrate contamination of spring waters in northern Florida. During base-flow conditions for the Suwannee River in 1997–1999, 17 water samples were collected from 12 first, second, and third magnitude springs discharging groundwater from the Upper Floridan aquifer. Extending age-dating techniques, using transient tracers to spring waters in complex karst systems, required an assessment of several models [piston-flow (PFM), exponential mixing (EMM), and binary-mixing (BMM)] to account for different distributions of groundwater age. Multi-tracer analyses of four springs yielded generally concordant PFM ages of around 20±2 years from CFC-12, CFC-113, 3H, and 3He, with evidence of partial CFC-11 degradation. The EMM gave a reasonable fit to CFC-113, CFC-12, and 3H data, but did not reproduce the observed 3He concentrations or 3H/3He ratios, nor did a combination PFM–EMM. The BMM could reproduce most of the multi-tracer data set only if both endmembers had 3H concentrations not much different from modern values. CFC analyses of 14 additional springs yielded apparent PFM ages from about 10 to 20 years from CFC-113, with evidence of partial CFC-11 degradation and variable CFC-12 contamination. While it is not conclusive, with respect to the age distribution within each spring, the data indicate that the average residence times were in the order of 10–20 years and were roughly proportional to spring magnitude. Applying similar models to recharge and discharge of nitrate based on historical nitrogen loading data yielded contrasting trends for Suwanee County and Lafayette County. In Suwanee County, spring nitrate trends and nitrogen isotope data were consistent with a peak in fertilizer input in the 1970s and a relatively high overall ratio of artificial fertilizer/manure; whereas in Lafayette County, spring nitrate trends and nitrogen isotope data were consistent with a more monotonic increase in fertilizer input and relatively low overall ratio of artificial fertilizer/manure. The combined results of this study indicate that the nitrate concentrations of springs in the Suwannee River basin have responded to increased nitrogen loads from various sources in the watersheds over the last few decades; however, the responses have been subdued and delayed because the average residence time of groundwater discharging from springs are in the order of decades.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lopes, E.S.N.; Cremasco, A.; Afonso, C.R.M.

Aging heat treatment can be a good way to optimize mechanical properties, changing the microstructure, and hence, the mechanical behavior of Ti alloys. The effects of aging heat treatments on {beta}-type Ti-30Nb alloy were investigated to evaluate the kinetics of {alpha}'' {yields} {alpha} + {beta} transformation. The results obtained from differential scanning calorimetry and high-temperature X-ray diffraction experiments indicated the complete decomposition of orthorhombic {alpha}'' phase at close to 300 deg. C, followed by {alpha} phase precipitation at 470 deg. C. The aging heat treatments also enabled us to observe a transformation sequence {alpha}'' {yields} {beta} + {omega} {yields} {beta}more » + {omega} + {alpha}, indicating martensite decomposition and {omega} phase precipitation at 260 deg. C after 2 h, followed by {alpha} phase nucleation after heating at 400 deg. C for 1 h. The elastic modulus and Vickers hardness of Ti-30Nb alloy were found to be very sensitive to the microstructural changes caused by heat treatment. - Highlights: {yields} DSC and XRD shed light on the {alpha}'' decomposition and nucleation of {omega} and {alpha} phases. {yields} Aging allows for {alpha}''{yields}{beta} transformation and nucleation of {omega} dispersed in the {beta} matrix. {yields} During aging, {alpha}'' interplanar distances are reduced to enable {beta} phase nucleation. {yields} Mechanical behavior is dependent on the microstructure and the phases in the alloy. {yields} It is not possible to obtain high strength and low elastic modulus by applying aging.« less

Predicting age from cortical structure across the lifespan.

PubMed

Madan, Christopher R; Kensinger, Elizabeth A

2018-03-01

Despite interindividual differences in cortical structure, cross-sectional and longitudinal studies have demonstrated a large degree of population-level consistency in age-related differences in brain morphology. This study assessed how accurately an individual's age could be predicted by estimates of cortical morphology, comparing a variety of structural measures, including thickness, gyrification and fractal dimensionality. Structural measures were calculated across up to seven different parcellation approaches, ranging from one region to 1000 regions. The age prediction framework was trained using morphological measures obtained from T1-weighted MRI volumes collected from multiple sites, yielding a training dataset of 1056 healthy adults, aged 18-97. Age predictions were calculated using a machine-learning approach that incorporated nonlinear differences over the lifespan. In two independent, held-out test samples, age predictions had a median error of 6-7 years. Age predictions were best when using a combination of cortical metrics, both thickness and fractal dimensionality. Overall, the results reveal that age-related differences in brain structure are systematic enough to enable reliable age prediction based on metrics of cortical morphology. © 2018 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Mitochondrial Aging Defects Emerge in Directly Reprogrammed Human Neurons due to Their Metabolic Profile.

PubMed

Kim, Yongsung; Zheng, Xinde; Ansari, Zoya; Bunnell, Mark C; Herdy, Joseph R; Traxler, Larissa; Lee, Hyungjun; Paquola, Apua C M; Blithikioti, Chrysanthi; Ku, Manching; Schlachetzki, Johannes C M; Winkler, Jürgen; Edenhofer, Frank; Glass, Christopher K; Paucar, Andres A; Jaeger, Baptiste N; Pham, Son; Boyer, Leah; Campbell, Benjamin C; Hunter, Tony; Mertens, Jerome; Gage, Fred H

2018-05-29

Mitochondria are a major target for aging and are instrumental in the age-dependent deterioration of the human brain, but studying mitochondria in aging human neurons has been challenging. Direct fibroblast-to-induced neuron (iN) conversion yields functional neurons that retain important signs of aging, in contrast to iPSC differentiation. Here, we analyzed mitochondrial features in iNs from individuals of different ages. iNs from old donors display decreased oxidative phosphorylation (OXPHOS)-related gene expression, impaired axonal mitochondrial morphologies, lower mitochondrial membrane potentials, reduced energy production, and increased oxidized proteins levels. In contrast, the fibroblasts from which iNs were generated show only mild age-dependent changes, consistent with a metabolic shift from glycolysis-dependent fibroblasts to OXPHOS-dependent iNs. Indeed, OXPHOS-induced old fibroblasts show increased mitochondrial aging features similar to iNs. Our data indicate that iNs are a valuable tool for studying mitochondrial aging and support a bioenergetic explanation for the high susceptibility of the brain to aging. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Duration of Louisville hotspot volcanism at IODP 330 sites Canopus, Burton, and Rigil via 40Ar/39Ar geochronology

NASA Astrophysics Data System (ADS)

Cohen, B. E.; Vasconcelos, P. M.; Koppers, A. A.; Thiede, D. S.

2013-12-01

The Louisville seamount trail is a chain of intraplate volcanoes constructed over the past ~80 million years, as the Pacific plate moved 4300 km over a long-lived mantle melting anomaly. During IODP Expedition 330, over 800 m of alkaline mafic volcanic lavas, as well as interbedded and overlying sediments, were recovered from five of these seamounts in the older (~80-50 Ma) part of the chain. In this study we have undertaken geochronology of the volcanic units to provide time constraints for the magmatic evolution of the volcanoes. Sixteen of these drilled lava flows have been successfully dated using MAP-215-50 spectrometers, with six samples analyzed at Oregon State University (Koppers et al. 2012) and 12 flows analyzed at The University of Queensland. To check for consistency, two lava flows were dated at both laboratories; both samples yielded results within 2σ error. To minimize the effects of seawater alteration, only samples with well-crystallized groundmass were picked, and material cleaned via HNO3 and HCl acid pretreatment. Plateaus comprise 61 to 87% of the 39Ar released, and 40Ar/36Ar vs. 39Ar/36Ar correlation diagrams reveal all samples contained trapped argon within error of modern-day atmosphere. All ages determined are consistent with stratigraphic constraints, and we interpret the results to be reliable estimates of eruption ages. Units from Burton Guyot (site U1376A) yield ages from 70.8 × 0.5 to 64.1 × 0.5 Ma (2σ, using the atmospheric argon ratio and decay constants from Steiger & Jäger (1978) and a Fish Canyon sanidine age of 28.02 (Renne et al. 1998)). This long (~7 Ma) duration is consistent with petrologic evidence for substantial post-shield volcanic activity at this site. Meanwhile, at Canopus (site U1372A) and Rigil (sites U1373A and U1374A), lavas from the base, middle, and top of the respective volcanic piles yielded ages within analytical error. At the two deepest sites (U1372A and 1374A) 187 and 505 m of volcanic rocks were drilled; the 2σ errors on the 40Ar/39Ar results constrain eruptions to less than 1.2 and 1.7 Ma respectively, indicating minimum eruption rates of ~200-300 m/Ma. These eruption rates are an order of magnitude lower than observed on Mauna Kea and Mauna Loa (2000-8000 m/Ma: Sharp & Renne 2005; Jourdan et al. 2012) and are consistent with the largely alkalic shield-building eruptions on Louisville versus tholeiitic shield stage observed on the Hawaii-Emperor chain. References Jourdan F. et al. (2012) Geochemistry, Geophysics, Geosystems, v13, Q05004. Koppers A.A.P. et al. (2012) Nature Geoscience, v5, p911-917. Renne P.R. et al. (1998) Chemical Geology, v145, p117-152. Sharp W.D. & Renne P.R. (2005) Geochemistry, Geophysics, Geosystems, v6, Q04G17. Steiger R.H. & Jäger E. (1977) Earth and Planetary Science Letters, v36, p359-362.

Detrital Record of Phanerozoic Tectonics in Iran: Evidence From U-Pb Zircon Geochronology

NASA Astrophysics Data System (ADS)

Horton, B. K.; Gillis, R. J.; Stockli, D. F.; Hassanzadeh, J.; Axen, G. J.; Grove, M.

2004-12-01

Ion-microprobe U-Pb ages of 91 detrital zircon grains supplement ongoing investigations of the tectonic history of Iran, a critical region bridging the gap between the Alpine and Himalayan orogenic belts. These data improve understanding of the distribution of continental blocks during a complex history of Late Proterozoic (Pan-African) crustal growth, Paleozoic passive-margin sedimentation, early Mesozoic collision with Eurasia, and Cenozoic collision with Arabia. U-Pb analyses of detrital zircon grains from four sandstone samples (two Lower Cambrian, one uppermost Triassic-Lower Jurassic, one Neogene) collected from the Alborz mountains of northern Iran reveal a spectrum of ages ranging from 50 to 2900 Ma. Most analyses yield concordant to moderately discordant ages. The Lower Cambrian Lalun and Barut sandstones yield age distribution peaks at approximately 550-650, 1000, and 2500 Ma, consistent with a Gondwanan source area presently to the south and west in parts of Iran and the Arabian-Nubian shield (Saudi Arabia and northwestern Africa). The uppermost Triassic-Lower Jurassic Shemshak Formation exhibits a broad range of U-Pb ages, including peaks of approximately 200-260, 330, 430, 600, and 1900 Ma, requiring a Eurasian source area presently to the north and east in the Turan plate (Turkmenistan and southwestern Asia). Neogene strata display both the youngest and oldest ages (approximately 50 and 2900 Ma) of any samples, a result of substantial sedimentary recycling of older Phanerozoic cover rocks. Because the youngest zircon ages for three of the four samples are indistinguishable from their stratigraphic (depositional) ages, these data suggest rapid exhumation and help constrain the termination age of Late Proterozoic-Early Cambrian (Pan-African) orogenesis and the timing of the Iran-Eurasia collision.

Zircon U-Pb ages, Hf isotope data, and tectonic implications of Early-Middle Triassic granitoids in the Ailaoshan high-grade metamorphic belt of Southeast Tibet

NASA Astrophysics Data System (ADS)

Wu, Wenbin; Liu, Junlai; Chen, Xiaoyu; Zhang, Lisheng

2017-04-01

The Ailaoshan tectonic belt, where the effects of the Paleo-Tethyan ocean evolution and Indian-Eurasian plate collision are superimposed, is one of the most significant geological discontinuities in western Yunnan province of southeast Tibet. An Ailaoshan micro-block within the belt is bounded by the Ailaoshan suture zone to the west and the Red River Fault to the east, and consists of low- and high-grade metamorphic belts. Late Permian-Middle Triassic granitoids that are widely distributed to the west of the Ailaoshan suture zone and within the Ailaoshan micro-block may yield significant information on the Tethyan tectonic evolution of the Ailaoshan tectonic belt. This study reports new LA-ICP-MS zircon U-Pb geochronology and Hf isotope data of four granitoids from the Ailaoshan high-grade metamorphic belt. Zircon grains from the Yinjie granitoid do not have inherited cores and yield a weighted mean U-Pb age of 247.1 ± 2.0 Ma. The zircon ɛ Hf( t) values range from 7.8 to 12.1, and Hf model ages from 775 to 546 Ma, indicating that the granitoid was derived from juvenile crust. The rims of zircons from the Majie and Yuanjiang granitoids yield weighted mean U-Pb ages of 239.5 ± 1.8 and 237.9 ± 2.6 Ma, respectively, whereas the cores yield ages of 1608-352 Ma. The ɛ Hf( t) values of zircon rims range from -20.4 to -5.3, yielding Hf model ages from 2557 to 1606 Ma and suggesting that the source magma of the Majie and Yuanjiang granitoids was derived from ancient crust. An additional granitoid located near the Majie Village yields a zircon U-Pb age of 241.2 ± 1.0 Ma. Based on our geochronological and geochemical data, combined with geological observations, we propose that the Ailaoshan micro-block was derived from the western margin of the Yangtze block, and is comparable to the Zhongzan and Nam Co micro-blocks. The presence of late Permian mafic rocks with rift-related geochemical characteristics within the Ailaoshan micro-block, together with granitoids derived from partial melting of ancient/juvenile crust, indicates the presence of an Ailaoshan rift. This possible rift may correspond to the Ganzi-Litang Ocean to the northwest and the Jinping-Song Da rift to the southeast. It is suggested that westward subduction of the Jinshajiang-Ailaoshan-Song Ma oceanic lithosphere triggered the separation of the Zhongzan, Ailaoshan, and Nam Co micro-blocks from the western passive continental margin of the Yangtze block through the opening of the Ganzi-Litang-Ailaoshan-Jinping-Song Da ocean/rift. This ocean/rift may represent a subsidiary branch of the Paleo-Tethyan Ocean along the western margin of the Yangtze block.

Cooling, exhumation, and kinematics of the Kanchenjunga Himal, far east Nepal

NASA Astrophysics Data System (ADS)

Larson, Kyle P.; Camacho, Alfredo; Cottle, John M.; Coutand, Isabelle; Buckingham, Heather M.; Ambrose, Tyler K.; Rai, Santa Man

2017-06-01

New single crystal 40Ar/39Ar and apatite fission track ages from the Kanchenjunga region of far east Nepal yield insight into the timing of assembly of the Himalayan midcrust and the mechanisms that controlled its exhumation. The 40Ar/39Ar data are compared with new U(Th)/Pb zircon and monazite intrusive crystallization ages and existing metamorphic monazite ages from across the study area to test for internal consistency and potential excess Ar contributions. This new data set, which significantly enhances the density and spatial coverage available from the region, shows that inferred thrust-sense discontinuities within the now-exhumed former midcrustal rocks exposed therein must have ceased motion by 12 Ma. Furthermore, the spatial distribution of ages across the Kanchenjunga region, older ages ( 12-16 Ma) to the south and north and younger ages ( 8 Ma) in the middle portion of the transect, is compatible with simulations of tectonic-enhanced exhumation above a developing duplex system in nearby Bhutan.

Radiocarbon constraints on fossil thinolite tufa formation in the Mono Basin, CA, USA

NASA Astrophysics Data System (ADS)

Leroy, S. L.; Zimmerman, S. R.; Hemming, S. R.; Stine, S.; Guilderson, T. P.

2009-12-01

Mono Lake is a terminal lake located at the western edge of the Great Basin, and is famous for its tufa towers. Thinolite, which is thought to be a CaCO3 pseudomorph of ikaite, is found around the Mono Basin in many fossil tufa towers, particularly at elevations above 2000 meters. The subaqueous parent mineral ikaite forms at low temperatures (< 6 °C) (Bischoff et al., 1993) and requires specific water chemistry. Previous radiocarbon dating of fossil tufa towers around the Mono Basin has yielded a rather small range of ages for the highest elevation towers, between 11.8 and 14.1 14C kyr BP (no corrections for reservoir effects have been made). A thinolite fan collected from outcrops in Mill Creek, just north of the current Mono Lake yielded an age of 10,690 ± 45 14C yr BP (12,750 ± 80 cal yr BP), consistent with a ca. 1000 year reservoir age and coincidence with thinolite crystals found in a core from the northwestern embayment of Mono Lake (Davis, 1999, QR), and thus correlating with the Younger Dryas cooling event as exhibited in the GISP2 δ18O record. While most of the thinolite textures are found at high elevations, we sampled a mound at 1955 meters (near the current shoreline, north of the lake and just east of Black Point) that has many concentric layers, some containing thinolite textures. Although tufa mounds can form very rapidly, the location at low elevation and the presence of at least 19 distinct layers led us to consider that this mound might represent a long term record of Mono Lake’s chemistry. The new data confirm that the mound formed over a long period within the last glacial cycle, with ages ranging beyond the current limits of measurement (>34 kyr) to as young as 15.5 14C kyr BP. In general there is a consistent stratigraphic trend of ages within the mound, but the thinolite ages are anomalously young and one thinolite sample shows a large age reversal. The best estimate of the age of the precipitation of this tufa mound is given by the non-thinolite textures. More work is needed to determine the best sampling and sample preparation strategies in order to get a reliable age model for this mound.

Defect design of insulation systems for photovoltaic modules

NASA Technical Reports Server (NTRS)

Mon, G. R.

1981-01-01

A defect-design approach to sizing electrical insulation systems for terrestrial photovoltaic modules is presented. It consists of gathering voltage-breakdown statistics on various thicknesses of candidate insulation films where, for a designated voltage, module failure probabilities for enumerated thickness and number-of-layer film combinations are calculated. Cost analysis then selects the most economical insulation system. A manufacturing yield problem is solved to exemplify the technique. Results for unaged Mylar suggest using fewer layers of thicker films. Defect design incorporates effects of flaws in optimal insulation system selection, and obviates choosing a tolerable failure rate, since the optimization process accomplishes that. Exposure to weathering and voltage stress reduces the voltage-withstanding capability of module insulation films. Defect design, applied to aged polyester films, promises to yield reliable, cost-optimal insulation systems.

14C dates from Tel Rehov: Iron-Age chronology, pharaohs, and Hebrew kings.

PubMed

Bruins, Hendrik J; van der Plicht, Johannes; Mazar, Amihai

2003-04-11

Stratified radiocarbon dates provide an independent chronological link between archaeological layers and historical data. The invasion by Pharaoh Shoshenq I (Shishak) is a key historical synchronism, approximately 925 B.C.E., mentioned in both Egyptian inscriptions and the Hebrew Bible. The list of places raided by Shoshenq, mentioned at Karnak (Egypt), includes Rehov (Israel). The site yielded a consistent series of radiocarbon dates from the 12th to 9th century B.C.E. Our results (i) suggest a revised Iron-Age chronology; (ii) date an archaeological stratum to Shoshenq's campaign; (iii) indicate the similarity of "Solomonic" and "Omride" pottery; and (iv) provide correlation with Greece and Cyprus.

Ca. 400 Ma Recrystallization of Norwegian Ultrahigh-pressure Eclogites: an ion Microprobe and Chemical Abrasion Study

NASA Astrophysics Data System (ADS)

Root, D. B.; Mattinson, J. M.; Hacker, B. R.; Wooden, J. L.

2002-12-01

Understanding the formation and exhumation of the ultrahigh-pressure (UHP) rocks of western Norway hinges on precise determination of the time of eclogite recrystallization. Our study consists of SHRIMP analysis, in conjunction with CL imagery, of zircon from four UHP and high-pressure (HP) eclogites; and detailed TIMS analysis of zircon from two samples subjected to combined thermal annealing and multi-step chemical abrasion (CA). SHRIMP analyses of the Otnheim and Langenes eclogites yield Caledonian spot ages of ca. 400 Ma from zircon rims. CL imagery and Th/U ratios from the Langenes eclogite indicate formation of rims by recrystallization of inherited zircon. SHRIMP analysis of the UHP Flatraket eclogite yielded a broad range of apparently concordant Caledonian ages. CA analyses of two fractions yielded moderate Pb loss from the first (lowest T) steps; possible minor Pb loss or minor growth at 400 Ma from the second steps; and a 407-404 Ma cluster of slightly discordant 206Pb/238U ages, most likely free from Pb loss, from the remaining steps. We interpret the latter to reflect recrystallization of inherited zircon, with possible new growth, at ca. 400-395 Ma. Alternatively, the high-temperature CA steps could represent growth at 407-404 Ma, with apparent discordance due to intermediate daughter product effects. HP/UHP zircon recrystallization in the Flatraket eclogite is inferred from three lines of evidence: i) zircon occurs as inclusions in garnet, omphacite, breunnerite, dolomite, and quartz, as well as in symplectites after phengite and omphacite; ii) association of zircon with rutile implies zircon formation during HP breakdown of Zr-ilmenite; and iii) chondrite-normalized ICP-MS analyses of the CA steps reveal small Eu anomalies and shallow HREE profiles, indicating zircon recrystallization in the presence of garnet. CA analysis of the Verpeneset eclogite yielded distinctly discordant step ages from two steps comprising <90% of the sample, with 206Pb/238U ages of 408 and 414 Ma. CL imagery indicates incomplete recrystallization of inherited igneous zircon, in keeping with steep HREE profiles determined from chondrite-normalized ICP-MS analyses. Our zircon age of ca. 400-395 Ma for the Flatraket eclogite is significantly younger than the 425 Ma age often cited for western Norway eclogite recrystallization, implying, in conjunction with 390-385 Ma 40Ar/39Ar white mica cooling ages, faster rates of exhumation (ca. 15 km/m.y.), and weakening the link between UHP metamorphism and ophiolite emplacement at 430-425 Ma.

Comparative Thermal Aging Effects on PM-HIP and Forged Inconel 690

NASA Astrophysics Data System (ADS)

Bullens, Alexander L.; Bautista, Esteban; Jaye, Elizabeth H.; Vas, Nathaniel L.; Cain, Nathan B.; Mao, Keyou; Gandy, David W.; Wharry, Janelle P.

2018-03-01

This study compares thermal aging effects in Inconel 690 (IN690) produced by forging and powder metallurgy with hot isostatic pressing (PM-HIP). Isothermal aging is carried out over 400-800°C for up to 1000 h and then metallography and nanoindentation are utilized to relate grain microstructure with hardness and yield strength. The PM-HIP IN690 maintains a constant grain size through all aging conditions, while the forged IN690 exhibits limited grain growth at the highest aging temperature and longest aging time. The PM-HIP IN690 exhibits comparable mechanical integrity as the forged material throughout aging: hardness and yield strength are unchanged with 100 h aging, but increase after 1000 h aging at all temperatures. In both the PM-HIP and forged IN690, the Hall-Petch relationship for Ni-based superalloys predicts yield strength for 0-100 h aged specimens, but underestimates yield strength in the 1000 h aged specimens because of thermally induced precipitation.

Water yields from forests: an agnostic view

Treesearch

Robert R. Ziemer

1987-01-01

Abstract - Although experimental watershed studies have consistently shown that water yield can be increased by removing trees and shrubs, programs to increase water yield on an operational scale have consistently failed. Failure has been related to overstated goals and benefits, unrealistic assumptions, political naivete, and the emergence of new interest groups....

Variscan ore formation and metamorphism at the Felbertal scheelite deposit (Austria): constraining tungsten mineralisation from Re-Os dating of molybdenite

NASA Astrophysics Data System (ADS)

Raith, Johann G.; Stein, Holly J.

2006-10-01

The Felbertal scheelite deposit in the Eastern Alps has been regarded as the type locality for stratabound scheelite deposits. It is hosted by a Cambro-Ordovician metavolcanic arc sequence with minor Variscan granitoids (˜ 340 Ma) in the central Tauern Window. Re-Os model ages for molybdenite from the Felbertal tungsten deposit range between ˜ 358 and ˜ 336 Ma and record several pulses of magmatic-hydrothermal-metamorphic molybdenite formation. Molybdenite ages from the K2 orebody, a scheelite-rich quartz mylonite in the Western ore field, indicate that both mineralisation and mylonite are Variscan in age and suggest that the shear zone was active for ˜ 20 million years. Early stage tungsten mineralisation ( Scheelite 1) in quartzitic ores in the Eastern ore field, which is free of molybdenite, yielded very low to near blank levels of Re and Os and thus could not be dated. However, molybdenite from scheelite-quartz stringers, previously interpreted as a feeder stockwork to quartzitic scheelite ore of presumed Cambrian age, yielded Variscan Re-Os ages of ˜ 342 and ˜ 337 Ma. Dating of molybdenite contained in scheelite ores thus far provides no indication of a Cambrian component to the tungsten mineralisation. Our data are consistent with a model of either granite intrusion-related ore formation and coeval metamorphic overprint during the Early Carboniferous or, alternatively, molybdenite formation may be exclusively attributed to Variscan metamorphism (see Stein 2006).

Protracted construction of gabbroic crust at a slow spreading ridge: Constraints from 206Pb/238U zircon ages from Atlantis Massif and IODP Hole U1309D (30°N, MAR)

USGS Publications Warehouse

Grimes, Craig B.; John, Barbara E.; Cheadle, Michael J.; Wooden, Joseph L.

2008-01-01

Sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon ages of 24 samples from oceanic crust recovered in Integrated Ocean Drilling Program (IODP) Hole U1309D and from the surface of Atlantis Massif, Mid-Atlantic Ridge (MAR) (30°N) document a protracted history of accretion in the footwall to an oceanic detachment fault. Ages for 18 samples of evolved Fe-Ti oxide gabbro and felsic dikes collected 40–1415 m below seafloor in U1309D yield a weighted mean of 1.20 ± 0.03 Ma (mean square of weighted deviates = 7.1). However, the ages range from 1.08 ± 0.07 Ma and 1.28 ± 0.05 Ma indicating crustal construction occurred over a minimum of 100–200 ka. The zircon ages, along with petrologic observations, indicate at least 2 major periods of intrusive activity with age peaks separated by 70 ka. The oldest ages are observed below 600 mbsf, an observation inconsistent with models requiring constant depth melt intrusion beneath a detachment fault. The data are most consistent with a “multiple sill” model whereby sills intrude at random depths below the ridge axis over a length scale greater than 1.4 km. Zircon ages from broadly spaced samples collected along the southern ridge of Atlantis Massif yield a detachment fault slip rate of 28.7 ± 6.7 mm/a and imply significant asymmetric plate spreading (up to 100% on the North American plate) for at least 200 ka during core complex formation.

Exposure age and erosional history of an upland planation surface in the US Atlantic Piedmont

USGS Publications Warehouse

Stanford, S.D.; Seidl, M.A.; Ashley, G.M.

2000-01-01

The upland planation surface in the Piedmont of central New Jersey consists of summit flats, as much as 130 km2 in area, that truncate bedding and structure in diabase, basalt, sandstone, mudstone and gneiss. These flats define a low-relief regional surface that corresponds in elevation to residual hills in the adjacent Coastal Plain capped by a fluvial gravel of late Miocene age. A Pliocene fluvial sand is inset 50 m below the upland features. These associations suggest a late Miocene or early Pliocene age for the surface. To assess exposure age and erosional history, a 4??4 m core of clayey diabase saprolite on a 3 km2 remnant of the surface was sampled at six depths for atmospherically produced cosmogenic 10Be. The measured inventory, assuming a deposition rate of 1??3 x 106 atoms cm-2 a-1, yields a minimum exposure age of 227 000 years, or, assuming continuous surface erosion, a constant erosion rate of 10 m Ma-1. Because the sample site lies about 60 m above the aggradation surface of the Pliocene fluvial deposit, and itself supports a pre-Pliocene fluvial gravel lag, this erosion rate is too high. Rather, episodic surface erosion and runoff bypassing probably have produced an inventory deficit. Reasonable estimates of surface erosion (up to 10 m) and bypassing (up to 50 per cent of total precipitation) yield exposure ages of as much as 6??4 Ma. These results indicate that (1) the surface is probably of pre-Pleistocene age and has been modified by Pleistocene erosion, and (2) exposure ages based on 10Be inventories are highly sensitive to surface erosion and runoff bypassing. Copyright (C) 2000 John Wiley and Sons, Ltd.

Age and duration of eclogite-facies metamorphism, North Qaidam HP/UHP terrane, Western China

USGS Publications Warehouse

Mattinson, C.G.; Wooden, J.L.; Liou, J.G.; Bird, D.K.; Wu, C.L.

2006-01-01

Amphibolite-facies para-and orthogneisses near Dulan, at the southeast end of the North Qaidam terrane, enclose minor eclogite and peridotite which record ultra-high pressure (UHP) metamorphism associated with the Early Paleozoic continental collision of the Qilian and Qaidam microplates. Field relations and coesite inclusions in zircons from paragneiss suggest that felsic, mafic, and ultramafic rocks all experienced UHP metamorphism and a common amphibolite-facies retrogression. SHRIMP-RG U-Pb and REE analyses of zircons from four eclogites yield weighted mean ages of 449 to 422 Ma, and REE patterns (flat HREE, no Eu anomaly) and inclusions of garnet, omphacite, and rutile indicate these ages record eclogite-facies metamorphism. The coherent field relations of these samples, and the similar range of individual ages in each sample suggests that the ???25 m.y. age range reflects the duration of eclogite-facies conditions in the studied samples. Analyses from zircon cores in one sample yield scattered 433 to 474 Ma ages, reflecting partial overlap on rims, and constrain the minimum age of eclogite protolith crystallization. Inclusions of Th + REE-rich epidote, and zircon REE patterns are consistent with prograde metamorphic growth. In the Lu??liang Shan, approximately 350 km northwest in the North Qaidam terrane, ages interpreted to record eclogite-facies metamorphism of eclogite and garnet peridotite are as old as 495 Ma and as young as 414 Ma, which suggests that processes responsible for extended high-pressure residence are not restricted to the Dulan region. Evidence of prolonged eclogite-facies metamorphism in HP/UHP localities in the Northeast Greenland eclogite province, the Western Gneiss Region of Norway, and the western Alps suggests that long eclogite-facies residence may be globally significant in continental subduction/collision zones.

Effect of total solids content and temperature on the rheological behaviour of reconstituted whole milk concentrates.

PubMed

Trinh, Binh; Trinh, Khanh Tuoc; Haisman, Derek

2007-02-01

This work investigated the combined effect of solids content, heating and storage temperatures on the rheological behaviour of reconstituted whole milk concentrates. The powder was reconstituted at 35 degrees C in a custom built recombination rig to various total solids content (TS) from 10-48% TS. The concentrates were then heated to 45-85 degrees C and stored at the heating temperature. The rheological behaviour shifter from Newtonian behaviour (below 30% TS) to power law (below 40% TS), with the yield stress observed from 40% TS upwards and time-dependent behaviour was noticed above 44% TS. Higher heating temperatures tend to promote non-Newtonian behaviour at lower solids content. The viscosity-solid content curve showed an exponential relationship, while the viscosity-temperature curve exhibited a minimum at 65-75 degrees C above 46% TS. During age thickening, the yield stress and the consistency coefficient increased, while the flow behaviour index decreased with storage time. This indicated that the milk concentrates deviated away from Newtonian behaviour during age thickening.

The active site of oxidative phosphorylation and the origin of hyperhomocysteinemia in aging and dementia.

PubMed

McCully, Kilmer S

2015-01-01

The active site of oxidative phosphorylation and adenosine triphosphate (ATP) synthesis in mitochondria is proposed to consist of two molecules of thioretinamide bound to cobalamin, forming thioretinaco, complexed with ozone, oxygen, nicotinamide adenine dinucleotide. and inorganic phosphate, TR2CoO3O2NAD(+)H2PO4(-). Reduction of the pyridinium nitrogen of the nicotinamide group by an electron from electron transport complexes initiates polymerization of phosphate with adenosine diphosphate, yielding nicotinamide riboside and ATP bound to thioretinaco ozonide oxygen. A second electron reduces oxygen to hydroperoxyl radical, releasing ATP from the active site. A proton gradient is created within F1F0 ATPase complexes of mitochondria by reaction of protons with reduced nicotinamide riboside and with hydroperoxyl radical, yielding reduced nicotinamide riboside and hydroperoxide. The hyperhomocysteinemia of aging and dementia is attributed to decreased synthesis of adenosyl methionine by thioretinaco ozonide and ATP, causing decreased allosteric activation of cystathionine synthase and decreased allosteric inhibition of methylenetetrahydrofolate reductase and resulting in dysregulation of methionine metabolism. © 2015 by the Association of Clinical Scientists, Inc.

Increased prevalence of sex chromosome aneuploidies in specific language impairment and dyslexia

PubMed Central

Simpson, Nuala H; Addis, Laura; Brandler, William M; Slonims, Vicky; Clark, Ann; Watson, Jocelynne; Scerri, Thomas S; Hennessy, Elizabeth R; Bolton, Patrick F; Conti-Ramsden, Gina; Fairfax, Benjamin P; Knight, Julian C; Stein, John; Talcott, Joel B; O'Hare, Anne; Baird, Gillian; Paracchini, Silvia; Fisher, Simon E; Newbury, Dianne F; Consortium, SLI

2014-01-01

Aim Sex chromosome aneuploidies increase the risk of spoken or written language disorders but individuals with specific language impairment (SLI) or dyslexia do not routinely undergo cytogenetic analysis. We assess the frequency of sex chromosome aneuploidies in individuals with language impairment or dyslexia. Method Genome-wide single nucleotide polymorphism genotyping was performed in three sample sets: a clinical cohort of individuals with speech and language deficits (87 probands: 61 males, 26 females; age range 4 to 23 years), a replication cohort of individuals with SLI, from both clinical and epidemiological samples (209 probands: 139 males, 70 females; age range 4 to 17 years), and a set of individuals with dyslexia (314 probands: 224 males, 90 females; age range 7 to 18 years). Results In the clinical language-impaired cohort, three abnormal karyotypic results were identified in probands (proband yield 3.4%). In the SLI replication cohort, six abnormalities were identified providing a consistent proband yield (2.9%). In the sample of individuals with dyslexia, two sex chromosome aneuploidies were found giving a lower proband yield of 0.6%. In total, two XYY, four XXY (Klinefelter syndrome), three XXX, one XO (Turner syndrome), and one unresolved karyotype were identified. Interpretation The frequency of sex chromosome aneuploidies within each of the three cohorts was increased over the expected population frequency (approximately 0.25%) suggesting that genetic testing may prove worthwhile for individuals with language and literacy problems and normal non-verbal IQ. Early detection of these aneuploidies can provide information and direct the appropriate management for individuals. PMID:24117048

The strain path dependence of plastic deformation response of AA5754: Experiment and modeling

NASA Astrophysics Data System (ADS)

Pham, Minh-Son; Hu, Lin; Iadicola, Mark; Creuziger, Adam; Rollett, Anthony D.

2013-12-01

This work presents modeling of experiments on a balanced biaxial (BB) pre-strained AA5754 alloy, subsequently reloaded uniaxially along the rolling direction and transverse direction. The material exhibits a complex plastic deformation response during the change in strain path due to 1) crystallographic texture, 2) aging (interactions between dislocations and Mg atoms) and 3) recovery (annihilation and re-arrangement of dislocations). With a BB prestrain of about 5 %, the aging process is dominant, and the yield strength for uniaxially deformed samples is observed to be higher than the flow stress during BB straining. The strain hardening rate after changing path is, however, lower than that for pre-straining. Higher degrees of pre-straining make the dynamic recovery more active. The dynamic recovery at higher strain levels compensates for the aging effect, and results in: 1) a reduction of the yield strength, and 2) an increase in the hardening rate of re-strained specimens along other directions. The yield strength of deformed samples is further reduced if these samples are left at room temperature to let static recovery occur. The synergistic influences of texture condition, aging and recovery processes on the material response make the modeling of strain path dependence of mechanical behavior of AA5754 challenging. In this study, the influence of crystallographic texture is taken into account by incorporating the latent hardening into a visco-plastic self-consistent model. Different strengths of dislocation glide interaction models in 24 slip systems are used to represent the latent hardening. Moreover, the aging and recovery effects are also included into the latent hardening model by considering strong interactions between dislocations and dissolved atom Mg and the microstructural evolution. These microstructural considerations provide a powerful capability to successfully describe the strain path dependence of plastic deformation behavior of AA5754.

U Pb ages of angrites

NASA Astrophysics Data System (ADS)

Amelin, Yuri

2008-01-01

Precise U-Pb ages, determined with double spike ( 202Pb- 205Pb) thermal ionization m1ass spectrometry, are reported for angrites Angra dos Reis (AdoR), Lewis Cliff 86010 (LEW), and D'Orbigny. Nineteen of 23 acid-washed pyroxene fractions from these meteorites and whole rock fractions from D'Orbigny contain between 0.5 and 1.3 pg of total common Pb, indistinguishable from analytical blank. Measured 206Pb/ 204Pb ratios in these fractions are between 6300 and 14,100 for AdoR, 1160-4500 for LEW, and 608-8500 for D'Orbigny. Blank-corrected 206Pb/ 204Pb ratios for all three meteorites vary from 2160 to over 100,000. These fractions yielded precise and reproducible 207Pb ∗/ 206Pb ∗ dates with the average values of 4557.65 ± 0.13 Ma for AdoR, 4558.55 ± 0.15 Ma for LEW, and 4564.42 ± 0.12 Ma for D'Orbigny. Pb-Pb isochrons including data with slightly elevated common Pb, and U-Pb upper concordia intercepts, yield similar dates. The implications of these new Pb-isotopic ages of angrites are threefold. First, they demonstrate that AdoR and LEW are not coeval, and the group of "slowly cooled" angrites is therefore genetically diverse. Second, the new age of LEW suggests an upward revision of 53Mn- 53Cr "absolute" ages by 0.7 Ma. Third, a precise age of D'Orbigny allows consistent linking of the 53Mn- 53Cr and 26Al- 26Mg extinct nuclide chronometers to the absolute lime scale.

External validation of anti-Müllerian hormone based prediction of live birth in assisted conception

PubMed Central

2013-01-01

Background Chronological age and oocyte yield are independent determinants of live birth in assisted conception. Anti-Müllerian hormone (AMH) is strongly associated with oocyte yield after controlled ovarian stimulation. We have previously assessed the ability of AMH and age to independently predict live birth in an Italian assisted conception cohort. Herein we report the external validation of the nomogram in 822 UK first in vitro fertilization (IVF) cycles. Methods Retrospective cohort consisting of 822 patients undergoing their first IVF treatment cycle at Glasgow Centre for Reproductive Medicine. Analyses were restricted to women aged between 25 and 42 years of age. All women had an AMH measured prior to commencing their first IVF cycle. The performance of the model was assessed; discrimination by the area under the receiver operator curve (ROCAUC) and model calibration by the predicted probability versus observed probability. Results Live births occurred in 29.4% of the cohort. The observed and predicted outcomes showed no evidence of miscalibration (p = 0.188). The ROCAUC was 0.64 (95% CI: 0.60, 0.68), suggesting moderate and similar discrimination to the original model. The ROCAUC for a continuous model of age and AMH was 0.65 (95% CI 0.61, 0.69), suggesting that the original categories of AMH were appropriate. Conclusions We confirm by external validation that AMH and age are independent predictors of live birth. Although the confidence intervals for each category are wide, our results support the assessment of AMH in larger cohorts with detailed baseline phenotyping for live birth prediction. PMID:23294733

Constraining Metamorphic Timing and Processes by Dating Garnet, Zircon, Titanite and Monazite in UHP and HP Rocks from Weihai, Sulu UHP Terrane, Eastern China

NASA Astrophysics Data System (ADS)

Wang, D.; Vervoort, J. D.; Fisher, C. M.; Cao, H.

2016-12-01

The Sulu UHP terrane is the extension of the Dabie orogenic belt to the east, offset 500 km to the northeast by the Tanlu fault [1]. The focus of this study, the Weihai area, is located at the northernmost part of the Sulu UHP terrane, and consists mainly of gneisses overprinted by amphibolite-facies assemblages, in addition to minor eclogite, granulite, and some ultramafic rocks [1]. Time constrains are critical to our understanding of the processes of UHP metamorphism, as well as the tectonic evolution of the region. In the last decade, U-Pb dating of metamorphic domains of zircons has been widely applied to determine the history of the UHP metamorphism (240 - 220 Ma) [1]. Recent garnet Lu-Hf dating from the Dabie terrane (240 - 220Ma) suggests the initiation of prograde metamorphism to be prior to ca. 240 Ma [2]. In-situ U-Pb dating of accessary minerals using LA-ICPMS (i.e. monazite, titanite, rutile, etc.), can provide important information to augment and complement the zircon U-Pb metamorphic dates. In this study, we collected samples throughout the Weihai area. Protolith ages of these samples range from Paleoproterozoic to Neoproterozoic ( 1850 - 700 Ma) as indicated by U-Pb dating of zircon cores. Zircon metamorphic rims yield U-Pb ages of 240 - 220 Ma, likely indicating the UHP stage of the Sulu terrane [3]. Four eclogites yield Lu-Hf garnet isochrons with dates between 239 and 224 Ma, consistent with garnet Lu-Hf dates from Dabie UHP terrane [2]. Sm-Nd isochrons indicate systematic younger dates (220 - 210 Ma) interpreted as cooling ages. Titanites extracted from four samples give U-Pb ages ranging from 220 to 200 Ma, in agreement with the titanite dates from the southern Sulu terrane [4]. Monazites from three samples give precise dates between 214 and 211 Ma. Collectively, monazite and titanite U-Pb ages are broadly consistent with the garnet Sm-Nd isochrons, and thus we interpret these as cooling ages. Based on the dates of different systems/minerals presented above, we suggest the prograde metamorphism of Weihai UHP terrane likely took place prior to 240 Ma, and the peak of the UHP stage is likely between 240 and 220 Ma. [1] Zhang et al., Gondwana Res., 16 (2009) 1-26 [2] Cheng et al., J. Metamorphic Geol., 26 (2008), 741-758 [3] Liou et al., J. Asian Earth Sci., 35 (2009), 199-231 [4] Chen and Zheng, GCA, 150(2015), 53-73

Age Spreads and the Temperature Dependence of Age Estimates in Upper Sco

NASA Astrophysics Data System (ADS)

Fang, Qiliang; Herczeg, Gregory J.; Rizzuto, Aaron

2017-06-01

Past estimates for the age of the Upper Sco Association are typically 11–13 Myr for intermediate-mass stars and 4–5 Myr for low-mass stars. In this study, we simulate populations of young stars to investigate whether this apparent dependence of estimated age on spectral type may be explained by the star formation history of the association. Solar and intermediate mass stars begin their pre-main sequence evolution on the Hayashi track, with fully convective interiors and cool photospheres. Intermediate-mass stars quickly heat up and transition onto the radiative Henyey track. As a consequence, for clusters in which star formation occurs on a timescale similar to that of the transition from a convective to a radiative interior, discrepancies in ages will arise when ages are calculated as a function of temperature instead of mass. Simple simulations of a cluster with constant star formation over several Myr may explain about half of the difference in inferred ages versus photospheric temperature; speculative constructions that consist of a constant star formation followed by a large supernova-driven burst could fully explain the differences, including those between F and G stars where evolutionary tracks may be more accurate. The age spreads of low-mass stars predicted from these prescriptions for star formation are consistent with the observed luminosity spread of Upper Sco. The conclusion that a lengthy star formation history will yield a temperature dependence in ages is expected from the basic physics of pre-main sequence evolution, and is qualitatively robust to the large uncertainties in pre-main sequence evolutionary models.

Movement between Mexico and Canada: Analysis of a New Migration Stream

PubMed Central

Massey, Douglas; Brown, Amelia E.

2011-01-01

In this analysis we use data from the Mexican Migration Project to contrast processes of Mexican migration to Canada and the United States. All migrants to Canada entered through the Seasonal Agricultural Worker Program and consistent with program criteria, migration there is strongly predicted by marital status and number of dependents, yielding a migrant population that is made up of males of prime labor-force age who are married and have multiple children at home. In contrast, the vast majority of migrants to the United States are undocumented and thus self-selected without regard to marital status or parenthood. Migration to the United States is strongly predicted by age, and migration probabilities display the age curve classically associated with labor migration. Within countries of destination, migrants to Canada enjoy superior labor market outcomes compared with those to the United States, with higher wages and more compact work schedules that yield higher earnings and shorter periods away from families compared with undocumented migrants to the United States. Labor migration to Canada also tends to operate as a circular flow with considerable repeat migration whereas undocumented migrants to the United States do not come and go so regularly, as crossing the Mexico-U.S. border has become increasingly difficult and costly. PMID:24347678

In situ radiometric and exposure age dating of the martian surface.

PubMed

Farley, K A; Malespin, C; Mahaffy, P; Grotzinger, J P; Vasconcelos, P M; Milliken, R E; Malin, M; Edgett, K S; Pavlov, A A; Hurowitz, J A; Grant, J A; Miller, H B; Arvidson, R; Beegle, L; Calef, F; Conrad, P G; Dietrich, W E; Eigenbrode, J; Gellert, R; Gupta, S; Hamilton, V; Hassler, D M; Lewis, K W; McLennan, S M; Ming, D; Navarro-González, R; Schwenzer, S P; Steele, A; Stolper, E M; Sumner, D Y; Vaniman, D; Vasavada, A; Williford, K; Wimmer-Schweingruber, R F

2014-01-24

We determined radiogenic and cosmogenic noble gases in a mudstone on the floor of Gale Crater. A K-Ar age of 4.21 ± 0.35 billion years represents a mixture of detrital and authigenic components and confirms the expected antiquity of rocks comprising the crater rim. Cosmic-ray-produced (3)He, (21)Ne, and (36)Ar yield concordant surface exposure ages of 78 ± 30 million years. Surface exposure occurred mainly in the present geomorphic setting rather than during primary erosion and transport. Our observations are consistent with mudstone deposition shortly after the Gale impact or possibly in a later event of rapid erosion and deposition. The mudstone remained buried until recent exposure by wind-driven scarp retreat. Sedimentary rocks exposed by this mechanism may thus offer the best potential for organic biomarker preservation against destruction by cosmic radiation.

In Situ Radiometric and Exposure Age Dating of the Martian Surface

NASA Technical Reports Server (NTRS)

Farley, K. A.; Malespin, C.; Mahaffy, P.; Grotzinger, J. P.; Vasconcelos, P. M.; Milliken, R. E.; Malin, M.; Edgett, K. S.; Pavlov, A. A.; Hurowitz, J. A.;

Paleomagnetic secular variation at the Azores during the last 3 ka

NASA Astrophysics Data System (ADS)

di Chiara, Anita; Speranza, Fabio; Porreca, Massimiliano

2012-07-01

We report on 33 new paleomagnetic directions obtained from 16 lava flows emplaced in the last 3 ka on São Miguel, the largest island of the Azores. The data provide 27 well-dated directions from historical or 14C dated flows which, together with 6 directions previously gathered from the same flows by Johnson et al. (1998), yield the first paleomagnetic directional record of the last 3 ka from the Atlantic Ocean. Within-flow directions are consistent, suggesting that inclination swings from 60° to 25° and declination changes between -10° to 20° reflect variations in the geomagnetic field over the last 3 ka. To a first approximation, the declination record is consistent with predictions from CALS3k.4 and gufm1 global field models. Conversely, inclination values are lower than model predictions at two different ages: 1) four sites from the 1652 AD flow yield I = 48° instead of I = 63° predicted by gufm1; 2) data from several flows nicely mimic the inclination minimum of 800-1400 AD, but inclination values are lower by ˜10° than CALS3k.4 model predictions. By interpolating a cubic spline fit on declination / inclination versus age data, we tentatively infer the directional evolution of the geomagnetic field at the Azores from 1000 BC to 1600 AD. The obtained curve shows three tracks in virtual overlap during the 1000-800 BC, 800-500 BC, and 400-700 AD time spans.

Aging of a Binary Colloidal Glass

NASA Astrophysics Data System (ADS)

Lynch, Jennifer M.; Cianci, Gianguido C.; Weeks, Eric R.

2008-03-01

After having undergone a glass transition, a glass is in a non-equilibrium state, and its properties depend on the time elapsed since vitrification. We study this phenomenon, known as aging. In particular, we study a colloidal suspension consisting of micron-sized particles in a liquid --- a good model system for studying the glass transition. In this system, the glass transition is approached by increasing the particle concentration, instead of decreasing the temperature. We observe samples composed of particles of two sizes (d1= 1.0μm and d2= 2.0μm) using fast laser scanning confocal microscopy, which yields real-time, three-dimensional movies deep inside the colloidal glass. We then analyze the trajectories of several thousand particles as the glassy suspension ages. Specifically, we look at how the size, motion and structural organization of the particles relate to the overall aging of the glass. We find that areas richer in small particles are more mobile and therefore contribute more to the structural changes found in aging glasses.

Are false-positive rates leading to an overestimation of noise-induced hearing loss?

PubMed

Schlauch, Robert S; Carney, Edward

2011-04-01

To estimate false-positive rates for rules proposed to identify early noise-induced hearing loss (NIHL) using the presence of notches in audiograms. Audiograms collected from school-age children in a national survey of health and nutrition (the Third National Health and Nutrition Examination Survey [NHANES III]; National Center for Health Statistics, 1994) were examined using published rules for identifying noise notches at various pass-fail criteria. These results were compared with computer-simulated "flat" audiograms. The proportion of these identified as having a noise notch is an estimate of the false-positive rate for a particular rule. Audiograms from the NHANES III for children 6-11 years of age yielded notched audiograms at rates consistent with simulations, suggesting that this group does not have significant NIHL. Further, pass-fail criteria for rules suggested by expert clinicians, applied to NHANES III audiometric data, yielded unacceptably high false-positive rates. Computer simulations provide an effective method for estimating false-positive rates for protocols used to identify notched audiograms. Audiometric precision could possibly be improved by (a) eliminating systematic calibration errors, including a possible problem with reference levels for TDH-style earphones; (b) repeating and averaging threshold measurements; and (c) using earphones that yield lower variability for 6.0 and 8.0 kHz--2 frequencies critical for identifying noise notches.

Evidence-Based Reading Instruction for Individuals with Autism Spectrum Disorders

PubMed Central

Whalon, Kelly J.; Al Otaiba, Stephanie; Delano, Monica E.

2009-01-01

Legislation mandates that all children, including children with autism spectrum disorders (ASD) be taught to read in ways that are consistent with reading research, and target the five components of evidence-based reading instruction: phonemic awareness, phonics, reading fluency, vocabulary and comprehension strategies. The purpose of this review is to synthesize the literature on reading instruction for children with ASD that encompasses one or more of the five components of reading. The review yielded 11 studies with 61 participants ages 4 to 17. Results indicate that children with ASD can benefit from reading instruction consistent with reading research. Research in this area is still preliminary, and more research is needed to guide practice. Possible directions for future research are provided. PMID:20161582

Application of U/Th and 40Ar/39Ar Dating to Orgnac 3, a Late Acheulean and Early Middle Palaeolithic Site in Ardèche, France

PubMed Central

Michel, Véronique; Shen, Guanjun; Shen, Chuan-Chou; Wu, Chung-Che; Vérati, Chrystèle; Gallet, Sylvain; Moncel, Marie-Hélène; Combier, Jean; Khatib, Samir; Manetti, Michel

2013-01-01

Refined radio-isotopic dating techniques have been applied to Orgnac 3, a Late Acheulean and Early Middle Palaeolithic site in France. Evidence of Levallois core technology appeared in level 4b in the middle of the sequence, became predominant in the upper horizons, and was best represented in uppermost level 1, making the site one of the oldest examples of Levallois technology. In our dating study, fourteen speleothem samples from levels 7, 6 and 5b, were U/Th-dated. Four pure calcite samples from the speleothem PL1 (levels 5b, 6) yield ages between 265 ± 4 (PL1-3) and 312 ± 15 (PL1-6) thousand years ago (ka). Three samples from the top of a second stalagmite, PL2, yield dates ranging from 288 ± 10 ka (PL2-1) to 298 ± 17 ka (PL2-3). Three samples from the base of PL2 (level 7) yield much younger U/Th dates between 267 and 283 ka. These dates show that the speleothems PL1 and PL2 are contemporaneous and formed during marine isotope stage (MIS) 9 and MIS 8. Volcanic minerals in level 2, the upper sequence, were dated by the 40Ar/39Ar method, giving a weighted mean of 302.9 ± 2.5 ka (2σ) and an inverse isochron age of 302.9 ± 5.9 ka (2σ). Both 40Ar/39Ar dating of volcanic sanidines and U/Th dating of relatively pure and dense cave calcites are known to be well established. The first parallel application of the two geochronometers to Orgnac 3 yields generally consistent results, which point to the reliability of the two methods. The difference between their age results is discussed. PMID:24349273

Application of U/Th and 40Ar/39Ar dating to Orgnac 3, a Late Acheulean and Early Middle Palaeolithic site in Ardèche, France.

PubMed

Michel, Véronique; Shen, Guanjun; Shen, Chuan-Chou; Wu, Chung-Che; Vérati, Chrystèle; Gallet, Sylvain; Moncel, Marie-Hélène; Combier, Jean; Khatib, Samir; Manetti, Michel

2013-01-01

Refined radio-isotopic dating techniques have been applied to Orgnac 3, a Late Acheulean and Early Middle Palaeolithic site in France. Evidence of Levallois core technology appeared in level 4b in the middle of the sequence, became predominant in the upper horizons, and was best represented in uppermost level 1, making the site one of the oldest examples of Levallois technology. In our dating study, fourteen speleothem samples from levels 7, 6 and 5b, were U/Th-dated. Four pure calcite samples from the speleothem PL1 (levels 5b, 6) yield ages between 265 ± 4 (PL1-3) and 312 ± 15 (PL1-6) thousand years ago (ka). Three samples from the top of a second stalagmite, PL2, yield dates ranging from 288 ± 10 ka (PL2-1) to 298 ± 17 ka (PL2-3). Three samples from the base of PL2 (level 7) yield much younger U/Th dates between 267 and 283 ka. These dates show that the speleothems PL1 and PL2 are contemporaneous and formed during marine isotope stage (MIS) 9 and MIS 8. Volcanic minerals in level 2, the upper sequence, were dated by the (40)Ar/(39)Ar method, giving a weighted mean of 302.9 ± 2.5 ka (2σ) and an inverse isochron age of 302.9 ± 5.9 ka (2σ). Both (40)Ar/(39)Ar dating of volcanic sanidines and U/Th dating of relatively pure and dense cave calcites are known to be well established. The first parallel application of the two geochronometers to Orgnac 3 yields generally consistent results, which point to the reliability of the two methods. The difference between their age results is discussed.

Reliability and validity of the McDonald Play Inventory.

PubMed

McDonald, Ann E; Vigen, Cheryl

2012-01-01

This study examined the ability of a two-part self-report instrument, the McDonald Play Inventory, to reliably and validly measure the play activities and play styles of 7- to 11-yr-old children and to discriminate between the play of neurotypical children and children with known learning and developmental disabilities. A total of 124 children ages 7-11 recruited from a sample of convenience and a subsample of 17 parents participated in this study. Reliability estimates yielded moderate correlations for internal consistency, total test intercorrelations, and test-retest reliability. Validity estimates were established for content and construct validity. The results suggest that a self-report instrument yields reliable and valid measures of a child's perceived play performance and discriminates between the play of children with and without disabilities. Copyright © 2012 by the American Occupational Therapy Association, Inc.

U-Pb geochronology and Hf-Nd isotope compositions of the oldest Neoproterozoic crust within the Cadomian orogen: new evidence for a unique juvenile terrane

NASA Astrophysics Data System (ADS)

Samson, S. D.; D'Lemos, R. S.; Blichert-Toft, J.; Vervoort, J.

2003-03-01

New U-Pb dates, combined with Nd and Hf isotopic data, from rocks within the Port Morvan area of the Baie de St Brieuc region of Brittany identify a unique portion of the Neoproterozoic Cadomia terrane. Two gneisses near Port Morvan yielded U-Pb dates of 754.6±0.8 Ma and 746.0±0.9 Ma, ages that are more than 130 Myr older than the oldest units formed during the main phase of early Cadomian magmatism. Two trondhjemite boulders from the monogenetic facies of the Cesson conglomerate yielded identical ages of 665.2±0.5 Ma and 665.5±0.7 Ma, and a cobble from the polygenetic facies yields a 207Pb- 206Pb date of 637±2 Ma. Individual detrital zircons from a sandstone associated with the Cesson conglomerates yield concordant U-Pb dates ranging from 650±3 Ma to 624.1±0.6 Ma. Initial ɛNd values for the rocks in this region range from +5.0 to +6.6, indicative of a substantial input from depleted mantle. Initial ɛHf values determined on zircons from these Neoproterozoic rocks, including the detrital zircons, range from +6.7 to +14.5, consistent with the Nd isotopic results. Maximum initial ɛHf values for two 2 Ga Icartian gneisses, considered basement to Cadomia, average +8.4 and +8.7. In contrast to the results of the Port Morvan rocks, 616-608 Ma syn-tectonic intrusions from Normandy and the British Channel Islands all have negative initial ɛNd values (-10.4 to -8.3) consistent with significant contamination by ancient crust such as the 2 Ga gneisses. The oldest arc-related magmas should have interacted most extensively with Cadomian basement, buffering younger mantle-derived magmas that were generated in subsequent magmatic episodes. The rocks within the Port Morvan region are thus inconsistent as examples of the earliest Cadomian intrusions as they show no evidence of interaction with 2 Ga basement. Instead, the older ages and mantle-like isotopic composition of these rocks suggest they are part of an independent terrane that formed prior to, and independently from, the Cadomian arc. Possible terrane-scale structural boundaries have recently been identified, including the newly recognized Port Morvan thrust fault and the NW-dipping Main Cadomian thrust.

The effect of age of cochlear implantation on vocal characteristics in children.

PubMed

Knight, Kerry; Ducasse, Simone; Coetzee, Ashley; van der Linde, Jeannie; Louw, Anel

2016-06-27

Early cochlear implantation aids auditory feedback and supports better communication and self-monitoring of the voice. The objective of this study was to determine whether the age of cochlear implantation has an impact on vocal development in children implanted before age 4. The study consisted of 19 participants in total. All implant recipients (experimental group) were 3-5 years post-implantation, including four prelingual (0-2 years) and five perilingual (2-4 years) implant recipients. The control group consisted of 10 children whose hearing was within normal limits between the ages 3-6 years and 10 months, which was compared to the experimental group. Established paediatric norms were used for additional comparison. A questionnaire was used to gather information from each of the participant's caregivers to determine whether other personal and contextual factors had an impact on voice production. An acoustic analysis was conducted for each participant using the Multi-Dimensional Voice Program of the Computerized Speech Lab. When the experimental group and the control group were compared, similar results were yielded for fundamental frequency and short-term perturbation (jitter and shimmer). More variability was noted in long-term frequency and amplitude measures, with significantly higher differences, and therefore further outside the norms, in the prelingual group when compared to the perilingual and control groups. In this study, age of implantation did not impact vocal characteristics. Further research should include larger sample sizes, with participants that are age and gender matched.

Measuring aging rates of mice subjected to caloric restriction and genetic disruption of growth hormone signaling

PubMed Central

Koopman, Jacob J.E.; van Heemst, Diana; van Bodegom, David; Bonkowski, Michael S.; Sun, Liou Y.; Bartke, Andrzej

2016-01-01

Caloric restriction and genetic disruption of growth hormone signaling have been shown to counteract aging in mice. The effects of these interventions on aging are examined through age-dependent survival or through the increase in age-dependent mortality rates on a logarithmic scale fitted to the Gompertz model. However, these methods have limitations that impede a fully comprehensive disclosure of these effects. Here we examine the effects of these interventions on murine aging through the increase in age-dependent mortality rates on a linear scale without fitting them to a model like the Gompertz model. Whereas these interventions negligibly and non-consistently affected the aging rates when examined through the age-dependent mortality rates on a logarithmic scale, they caused the aging rates to increase at higher ages and to higher levels when examined through the age-dependent mortality rates on a linear scale. These results add to the debate whether these interventions postpone or slow aging and to the understanding of the mechanisms by which they affect aging. Since different methods yield different results, it is worthwhile to compare their results in future research to obtain further insights into the effects of dietary, genetic, and other interventions on the aging of mice and other species. PMID:26959761

Measuring aging rates of mice subjected to caloric restriction and genetic disruption of growth hormone signaling.

PubMed

Koopman, Jacob J E; van Heemst, Diana; van Bodegom, David; Bonkowski, Michael S; Sun, Liou Y; Bartke, Andrzej

2016-03-01

Caloric restriction and genetic disruption of growth hormone signaling have been shown to counteract aging in mice. The effects of these interventions on aging are examined through age-dependent survival or through the increase in age-dependent mortality rates on a logarithmic scale fitted to the Gompertz model. However, these methods have limitations that impede a fully comprehensive disclosure of these effects. Here we examine the effects of these interventions on murine aging through the increase in age-dependent mortality rates on a linear scale without fitting them to a model like the Gompertz model. Whereas these interventions negligibly and non-consistently affected the aging rates when examined through the age-dependent mortality rates on a logarithmic scale, they caused the aging rates to increase at higher ages and to higher levels when examined through the age-dependent mortality rates on a linear scale. These results add to the debate whether these interventions postpone or slow aging and to the understanding of the mechanisms by which they affect aging. Since different methods yield different results, it is worthwhile to compare their results in future research to obtain further insights into the effects of dietary, genetic, and other interventions on the aging of mice and other species.

The 3.66 Ga Nuvvuagittuq Tonalite-Trondhjemite-Granodiorite Suite: A Case of Hadean Anatexis

NASA Astrophysics Data System (ADS)

Stevenson, R. K.; Bizzarro, M.

2011-12-01

The ca 3.8-4.3 Ga Nuvvuagittuq supracrustal sequence in northern Quebec, Canada, ranks as one of the most exciting early Earth terrain discoveries of the past fifteen years. The supracrustal sequence consists of mafic amphibolite rocks with rare felsic schists along with ultramafic sills and oxide-rich and quartz-rich iron formation. The supracrustal sequence is semi-oval in form and is folded around a core of foliated tonalite-trondhjemite-granodiorite (TTG) suite. A similar TTG suite forms a sheath around the exterior margin of the Nuvvuagittuq supracrustal sequence. Zircons from a felsic volcanic unit within the sequence yielded a minimum age of 3.8 Ga (U-Pb) for volcanic rocks of the sequence (David et al. 2009). A study of the Nd142 isotope systematics of the sequence found evidence for a Nd142 deficit in the sequence and a Nd142-Sm147 isochron yielded an age of 4.28 Ga (O'Neil et al. 2008). Dating of zircons from the tonalite sheath (U-Pb TIMS; David et al., 2009) and from the inner core (U-Pb SHRIMP; this study) yield similar ages (3.66 Ga). Zircons from this sequence undoubtedly contributed to the Hf isotopic composition of Archean sedimentary sequences of the Canadian Shield (Stevenson and Patchett 1990).The zircons from the TTG suite are very homogeneous and only have rare thin metamorphic rims that yield an age of 2.7 Ga (U-Pb Shrimp; this study). Radiogenic isotope studies (Sm-Nd and Lu-Hf) indicate that the TTG suite is an anatectic product of the melting of the Nuvvuagittuq supracrustal suite. The geochemical compositions of the Nuvvuagittuq TTG suite are compared with the compositions of ca 3.6 TTG suites from other localities around the world. David, J. Godin, L., Stevenson, R., O'Neil, J. and Francis, D. 2009. U-Pb ages (3.8-2.7 Ga) and Nd isotope data from the newly- identified Eoarchean Nuvvuagittuq supracrustal sequence, Superior Craton, Canada. GSA Bulletin 121; 150-163. O'Neil, J., Carlson, R.W., Francis, D., and Stevenson, R.K. 2008. Neodymium-142 Evidence Hadean Mafic Crust. Science 321 (Sept. 26), 1828-1831. Stevenson, R.K. and Patchett, P.J. (1990): Implications for the evolution of continental crust from Hf isotope systematics of Archean detrital zircons. Geochimica et Cosmochimica Acta 54, 1683-1697.

Cover sequences at the northern margin of the Antongil Craton, NE Madagascar

USGS Publications Warehouse

Bauer, W.; Walsh, G.J.; De Waele, B.; Thomas, Ronald J.; Horstwood, M.S.A.; Bracciali, L.; Schofield, D.I.; Wollenberg, U.; Lidke, D.J.; Rasaona, I.T.; Rabarimanana, M.H.

2011-01-01

The island of Madagascar is a collage of Precambrian, generally high-grade metamorphic basement domains, that are locally overlain by unmetamorphosed sedimentary rocks and poorly understood low-grade metasediments. In the Antalaha area of NE Madagascar, two distinct cover sequences rest on high-grade metamorphic and igneous basement rocks of the Archaean Antongil craton and the Neoproterozoic Bemarivo belt. The older of these two cover sequences, the Andrarona Group, consists of low-grade metasedimentary rocks. The younger sequence, the newly defined Ampohafana Formation, consists of unmetamorphosed sedimentary rocks. The Andrarona Group rests on Neoarchaean granites and monzogranites of the Antongil craton and consists of a basal metagreywacke, thick quartzites and an upper sequence of sericite-chlorite meta-mudstones, meta-sandstones and a volcaniclastic meta-sandstone. The depositional age of the volcaniclastic meta-sandstone is constrained in age by U–Pb laser-ablation ICP-MS analyses of euhedral zircons to 1875 ± 8 Ma (2σ). Detrital zircons of Archaean and Palaeoproterozoic age represent an input from the Antongil craton and a newly defined Palaeoproterozoic igneous unit, the Masindray tonalite, which underlies the Andrarona Group, and yielded a U–Pb zircon age of 2355 ± 11 Ma (2σ), thus constraining the maximum age of deposition of the basal part of the Andrarona Group. The Andrarona Group shows a low-grade metamorphic overprint in the area near Antalaha; illite crystallinity values scatter around 0.17°Δ2Θ CuKα, which is within the epizone. The Ampohafana Formation consists of undeformed, polymict conglomerate, cross-bedded sandstone, and red mudstone. An illite crystallinity value of >0.25°Δ2Θ CuKα obtained from the rocks is typical of the diagenetic zone. Occurrences of rhyodacite pebbles in the Ampohafana Formation and the intrusion of a basaltic dyke suggest a deposition in a WSW-ENE-trending graben system during the opening of the Indian Ocean in the Upper Cretaceous, that was characterized by extensive rhyolitic to basaltic magmatism along Madagascar's eastern coast.

Optically stimulated luminescence dating of late Holocene raised strandplain sequences adjacent to Lakes Michigan and Superior, Upper Peninsula, Michigan, USA

USGS Publications Warehouse

Argyilan, Erin P.; Forman, Steven L.; Johnston, John W.; Wilcox, Douglas A.

2005-01-01

This study evaluates the accuracy of optically stimulated luminescence to date well-preserved strandline sequences at Manistique/Thompson bay (Lake Michigan), and Tahquamenon and Grand Traverse Bays (Lake Superior) that span the past ∼4500 yr. The single aliquot regeneration (SAR) method is applied to produce absolute ages for littoral and eolian sediments. SAR ages are compared against AMS and conventional 14C ages on swale organics. Modern littoral and eolian sediments yield SAR ages 14C ages on swale organics. Significant variability in 14C ages >2000 cal yr B.P. complicates comparison to SAR ages at all sites. However, a SAR age of 4280 ± 390 yr (UIC913) on ridge77 at Tahquamenon Bay is consistent with regional regression from the high lake level of the Nipissing II phase ca. 4500 cal yr B.P. SAR ages indicate a decrease in ridge formation rate after ∼1500 yr ago, likely reflecting separation of Lake Superior from lakes Huron and Michigan. This study shows that SAR is a credible alternative to 14C methods for dating littoral and eolian landforms in Great Lakes and other coastal strandplains where 14C methods prove problematic.

Ground-water resources of McKenzie County, North Dakota. Part III

DOE Office of Scientific and Technical Information (OSTI.GOV)

Croft, M.G.

Ground water suitable for domestic and livestock supplies in McKenzie County is available from three aquifer systems in semiconsolidated rocks of Late Cretaceous and Tertiary age. Ground water from aquifers in unconsolidated sand and gravel of Quaternary age is suitable for domestic, livestock, municipal, industrial, and irrigation uses. Rocks older than Late Cretaceous age extend to 15,000 feet (4572 meters) and generally contain brackish water that is unsuitable for most purposes. The Fox Hills and basal Hell Creek aquifer system is used as a source for livestock and domestic supplies. It generally is 1100 to 1800 feet (335 to 549more » meters) in depth, and the transmissivity is 200 to 300 feet squared per day (19 to 28 meters squared per day). The water is lower in dissolved solids than water in overlying aquifers of Tertiary age and has a median dissolved-solids concentration of about 1325 milligrams per liter. Wells may yield 100 gallons per minute (6.3 liters per second). Six aquifers, each consisting of 50 to 176 feet (15 to 54 meters) of unconsolidated sand and gravel of Quaternary age, occur in McKensie County. The sand and gravel could yield 100 to more than 500 gallons per minute (6.3 to 32 liters per second). The water from four of the aquifers generally is a sodium bicarbonate type and has a median dissolved-solids concentration of 1100 to 2330 milligrams per liter. Water from the Charbonneau, Tobacco Garden, and Yellowstone-Missouri aquifers is suitable for irrigation. 26 figs., 9 tabs.« less

An autochthonous Avalonian basement source for the latest Ordovician Brenton Pluton in the Meguma terrane of Nova Scotia: U-Pb-Hf isotopic constraints and paleogeographic implications

NASA Astrophysics Data System (ADS)

Duncan Keppie, J.; Gregory Shellnutt, J.; Dostal, Jaroslav; Fraser Keppie, D.

2018-04-01

The Ediacaran-Ordovician Meguma Supergroup was thrust over Avalonia basement prior to the intrusion of post-Acadian, ca. 370 Ma, S-type granitic batholiths. This has led to two main hypotheses regarding the original location of the Meguma terrane, a continental rise prism bordering either NW Africa or Avalonia. On the other hand, the pre-Acadian, ca. 440 Ma Brenton pluton has yielded the following U/Pb LA-ICP-MS zircon data: (1) 448 ± 3 Ma population peak inferred to be the intrusive age and (2) ca. 550 and 700 Ma inherited ages common to both Avalonia and NW Africa. In contrast, Hf isotopic analyses of zircon yielded model ages ranging from 814 to 1127 Ma with most between 940 and 1040 Ma: such ages are typical of Avalonia and not NW Africa. The ages of the inherited zircons found within the Brenton pluton suggest that it was probably derived by partial melting of sub-Meguma, mid-crustal Avalonian rocks, upon which the Meguma Supergroup was deposited. Although Avalonia is commonly included in the peri-Gondwanan terranes off NW Africa or Amazonia, paleomagnetic data, faunal provinciality, and Hf data suggest that, during the Ediacaran-Early Cambrian, it was an island chain lying near the tropics (ca. 20-30 °S) and was possibly a continuation of the Bolshezemel volcanic arc accreted to northern Baltica during the Ediacaran Timanide orogenesis. This is consistent with the similar derital zircon population in the Ediacaran-Cambrian Meguma Supergroup and the Dividal Group in northeastern Baltica.

Refined depositional history and dating of the Tongaporutuan reference section, north Taranaki, New Zealand: new volcanic ash U-Pb zircon ages, biostratigraphy and sedimentation rates

USGS Publications Warehouse

Maier, K.L.; Crundwell, Martin P.; Coble, Matthew A.; Kingsley-Smith, Peter R.; Graham, Stephan A.

2016-01-01

This study presents new radiometric ages from volcanic ash beds within a c. 1900 m thick, progradational, deep-water clastic slope succession of late Miocene age exposed along the north Taranaki coast of the North Island, New Zealand. The ash beds yield U–Pb zircon ages ranging from 10.63 ± 0.65 Ma to 8.97 ± 0.22 Ma. The new ages are compatible with and provide corroboration of New Zealand Tongaporutuan Stage planktic foraminiferal and bolboformid biostratigraphic events identified in the same section. The close accord between these two age datasets provides a stratigraphically consistent and coherent basis for examining margin evolution. The arrival of a prograding clastic wedge and ensuing upward shoaling is recorded by sedimentation rates c. 2000 m/Ma–1 that are an order of magnitude higher than sedimentation rates on the precursor deep basin floor. This outcrop study provides new constraints for interpreting analogous subsurface deposits in Taranaki Basin and complements the regional late Miocene biostratigraphic dating framework.

Petrogenesis of the Majiari ophiolite (western Tibet, China): Implications for intra-oceanic subduction in the Bangong-Nujiang Tethys

NASA Astrophysics Data System (ADS)

Huang, Qiang-tai; Liu, Wei-liang; Xia, Bin; Cai, Zhou-rong; Chen, Wei-yan; Li, Jian-feng; Yin, Zheng-xin

2017-09-01

The Majiari ophiolite lies in the western Bangong-Nujiang Suture Zone, which separates the Qiangtang and Lhasa blocks in central Tibet. The ophiolite consists of peridotite, gabbro/diabase and basalt. Zircon U-Pb dating yielded an age of 170.5 ± 1.7 Ma for the gabbro, whereas 40Ar/39Ar dating of plagioclase from the same gabbro yielded ages of 108.4 ± 2.6 Ma (plateau age) and 112 ± 2 Ma (isochron age), indicating that the ophiolite was formed during the Middle Jurassic and was probably emplaced during the Early Cretaceous. Zircons from the gabbro have εHf(t) values ranging from +6.9 to +10.6 and f(Lu/Hf) values ranging from -0.92 to -0.98. Mafic lavas plot in the tholeiitic basalt field but are depleted in Nb, Ta and Ti and enriched in Rb, Ba and Th in the N-MORB-normalized trace element spider diagram. These lavas have whole-rock εNd(t) values of +5.9 to +6.6, suggesting that they were derived from a depleted mantle source, which was probably modified by subducted materials. The Majiari ophiolite probably formed in a typical back-arc basin above a supra-subduction zone (SSZ) mantle wedge. Intra-oceanic subduction occurred during the Middle Jurassic and collision of the Lhasa and South Qiangtang terranes likely occurred in the Early Cretaceous. Thus, closure of the Bangong-Nujiang Tethys Ocean likely occurred before the Early Cretaceous.

Within-subject neural reactivity to reward and threat is inverted in young adolescents.

PubMed

Thomason, M E; Marusak, H A

2017-07-01

As children mature, they become increasingly independent and less reliant on caregiver support. Changes in brain systems are likely to stimulate and guide this process. One mechanistic hypothesis suggests that changes in neural systems that process reward and threat support the increase in exploratory behavior observed in the transition to adolescence. This study examines the basic tenets of this hypothesis by performing functional magnetic resonance imaging (fMRI) during well-established reward and threat processing tasks in 40 children and adolescents, aged 9-15 years. fMRI responses in the striatum and amygdala are fit to a model predicting that striatal reward and amygdala threat-responses will be unrelated in younger participants (aged 9-12 years), while older participants (aged 13-15 years) will differentially engage these structures. Our data are consistent with this model. Activity in the striatum and amygdala are comparable in younger children, but in older children, they are inversely related; those more responsive to reward show a reduced threat-response. Analyses testing age as a continuous variable yield consistent results. In addition, the proportion of threat to reward-response relates to self-reported approach behavior in older but not younger youth, exposing behavioral relevance in the relative level of activity in these structures. Results are consistent with the notion that both individual and developmental differences drive reward-seeking behavior in adolescence. While these response patterns may serve adaptive functions in the shift to independence, skew in these systems may relate to increased rates of emotional psychopathology and risk-taking observed in adolescence.

Preserved Flora and Organics in Impact Melt Breccias

NASA Technical Reports Server (NTRS)

Schultz, P. H.; Harris, R. Scott; Clemett, S. J.; Thomas-Keprta, K. L.; Zarate, M.

2014-01-01

At least seven glass-bearing strata of varying ages occur at different horizons in the Pampean sediments of Argentina dating back to the Miocene. In a strict sense, these impact glasses are melt-matrix breccias composed of partially digested minerals clasts and basement fragments indicative of crater excavation. Ar-40/Ar-39 dating yield ages (+/- 2 sigma) of 6 +/- 2 Ka, 114 +/- 26 Ka, 230 +/- 30 Ka, 445 +/- 21 Ka, 3.27 +/- 0.08 Ma (near Mar del Plata = MdP), 5.28 +/- 0.04 Ma, and 9.21 +/- 0.08 Ma (near Chasico = CH) Where found in place (not reworked), these ages are consistent with the local stratigraphy and faunal assemblages. A striking property of some of these impact glasses is the encapsulation of preserved fragments of floral (and even soft-tissue faunal remains). Here we identify retained organics and describe a likely process of encapsulation and preservation.

Genome flux and stasis in a five millennium transect of European prehistory

PubMed Central

Gamba, Cristina; Jones, Eppie R.; Teasdale, Matthew D.; McLaughlin, Russell L.; Gonzalez-Fortes, Gloria; Mattiangeli, Valeria; Domboróczki, László; Kővári, Ivett; Pap, Ildikó; Anders, Alexandra; Whittle, Alasdair; Dani, János; Raczky, Pál; Higham, Thomas F. G.; Hofreiter, Michael; Bradley, Daniel G; Pinhasi, Ron

2014-01-01

The Great Hungarian Plain was a crossroads of cultural transformations that have shaped European prehistory. Here we analyse a 5,000-year transect of human genomes, sampled from petrous bones giving consistently excellent endogenous DNA yields, from 13 Hungarian Neolithic, Copper, Bronze and Iron Age burials including two to high (~22 × ) and seven to ~1 × coverage, to investigate the impact of these on Europe’s genetic landscape. These data suggest genomic shifts with the advent of the Neolithic, Bronze and Iron Ages, with interleaved periods of genome stability. The earliest Neolithic context genome shows a European hunter-gatherer genetic signature and a restricted ancestral population size, suggesting direct contact between cultures after the arrival of the first farmers into Europe. The latest, Iron Age, sample reveals an eastern genomic influence concordant with introduced Steppe burial rites. We observe transition towards lighter pigmentation and surprisingly, no Neolithic presence of lactase persistence. PMID:25334030

Genome flux and stasis in a five millennium transect of European prehistory.

PubMed

Gamba, Cristina; Jones, Eppie R; Teasdale, Matthew D; McLaughlin, Russell L; Gonzalez-Fortes, Gloria; Mattiangeli, Valeria; Domboróczki, László; Kővári, Ivett; Pap, Ildikó; Anders, Alexandra; Whittle, Alasdair; Dani, János; Raczky, Pál; Higham, Thomas F G; Hofreiter, Michael; Bradley, Daniel G; Pinhasi, Ron

2014-10-21

The Great Hungarian Plain was a crossroads of cultural transformations that have shaped European prehistory. Here we analyse a 5,000-year transect of human genomes, sampled from petrous bones giving consistently excellent endogenous DNA yields, from 13 Hungarian Neolithic, Copper, Bronze and Iron Age burials including two to high (~22 × ) and seven to ~1 × coverage, to investigate the impact of these on Europe's genetic landscape. These data suggest genomic shifts with the advent of the Neolithic, Bronze and Iron Ages, with interleaved periods of genome stability. The earliest Neolithic context genome shows a European hunter-gatherer genetic signature and a restricted ancestral population size, suggesting direct contact between cultures after the arrival of the first farmers into Europe. The latest, Iron Age, sample reveals an eastern genomic influence concordant with introduced Steppe burial rites. We observe transition towards lighter pigmentation and surprisingly, no Neolithic presence of lactase persistence.

Analyses of Factors Affecting Endothelial Cell Density in an Eye Bank Corneal Donor Database.

PubMed

Kwon, Ji Won; Cho, Kyong Jin; Kim, Hong Kyu; Lee, Jimmy K; Gore, Patrick K; McCartney, Mitchell D; Chuck, Roy S

2016-09-01

To analyze the factors affecting central corneal endothelial cell density (ECD) in an eye bank corneal donor database. The Lion's Eye Institute corneal donor database consisting of 18,665 donors (34,234 corneas) aged 20 years or older was analyzed. In particular, differences in the ECD based on age, sex, race, prior ocular surgery, a history of systemic diseases, and smoking were investigated. Furthermore, risk factors for donor cell count inadequacy (defined here as ECD less than 2000/mm) were identified. ECD decreased with age. Regarding race, the average ECD of African American donors was higher than those of white or Hispanic donors. A history of diabetes mellitus (DM) and ocular surgery were associated with a lower ECD. Donor medical history of hypertension, glaucoma, depression, dementia, Parkinson disease, hyper- or hypothyroidism, or smoking did not seem to affect the ECD. The risk factors for donor cell count inadequacy, based on binary logistic regression analyses were advanced age [65-74 years yielded an odds ratio of 17.8; confidence interval (CI), 10.6-29.8; P < 0.001; and 75-99 years yielded an odds ratio of 24.6 (CI, 14.5-41.61; P < 0.001) when compared with 20-34 years], cataract surgery (odds ratio, 4.3; CI, 4.0-4.8; P < 0.001), and DM (odds ratio, 1.2; CI, 1.1-1.3; P = 0.001). Age, race, ocular surgery (cataract and refractive), and DM seem to significantly affect donor corneal ECD. Of these variables, age, a history of cataract surgery, and DM were found to be the greatest risk factors for inadequate donor cell density (less than 2000/mm).

Increased prevalence of sex chromosome aneuploidies in specific language impairment and dyslexia.

PubMed

Simpson, Nuala H; Addis, Laura; Brandler, William M; Slonims, Vicky; Clark, Ann; Watson, Jocelynne; Scerri, Thomas S; Hennessy, Elizabeth R; Bolton, Patrick F; Conti-Ramsden, Gina; Fairfax, Benjamin P; Knight, Julian C; Stein, John; Talcott, Joel B; O'Hare, Anne; Baird, Gillian; Paracchini, Silvia; Fisher, Simon E; Newbury, Dianne F

2014-04-01

Sex chromosome aneuploidies increase the risk of spoken or written language disorders but individuals with specific language impairment (SLI) or dyslexia do not routinely undergo cytogenetic analysis. We assess the frequency of sex chromosome aneuploidies in individuals with language impairment or dyslexia. Genome-wide single nucleotide polymorphism genotyping was performed in three sample sets: a clinical cohort of individuals with speech and language deficits (87 probands: 61 males, 26 females; age range 4 to 23 years), a replication cohort of individuals with SLI, from both clinical and epidemiological samples (209 probands: 139 males, 70 females; age range 4 to 17 years), and a set of individuals with dyslexia (314 probands: 224 males, 90 females; age range 7 to 18 years). In the clinical language-impaired cohort, three abnormal karyotypic results were identified in probands (proband yield 3.4%). In the SLI replication cohort, six abnormalities were identified providing a consistent proband yield (2.9%). In the sample of individuals with dyslexia, two sex chromosome aneuploidies were found giving a lower proband yield of 0.6%. In total, two XYY, four XXY (Klinefelter syndrome), three XXX, one XO (Turner syndrome), and one unresolved karyotype were identified. The frequency of sex chromosome aneuploidies within each of the three cohorts was increased over the expected population frequency (approximately 0.25%) suggesting that genetic testing may prove worthwhile for individuals with language and literacy problems and normal non-verbal IQ. Early detection of these aneuploidies can provide information and direct the appropriate management for individuals. © 2013 The Authors. Developmental Medicine & Child Neurology published by John Wiley & Sons Ltd on behalf of Mac Keith Press.

Effect of bovine somatotropin and rumen-undegradable protein on mammary growth of prepubertal dairy heifers and subsequent milk production.

PubMed

Capuco, A V; Dahl, G E; Wood, D L; Moallem, U; Erdman, R E

2004-11-01

Rapid body growth during the prepubertal period may be associated with reductions in mammary parenchymal growth and subsequent milk yield. The objective of this study was to test effects of dietary rumen-undegradable protein (RUP) and administration of recombinant bovine somatotropin (bST) during the prepubertal period on mammary growth and milk yield of dairy heifers. Seventy-two Holstein heifers were used in the experiment. At 90 d of age, 8 heifers were slaughtered before initiation of treatment. Remaining heifers were assigned randomly to 1 of 4 treatments. Treatments consisted of a control diet (5.9% RUP, 14.9% CP, DM basis) or RUP-supplemented diet (control diet plus 2% added RUP) with or without 0.1 mg of bST/kg of BW per day applied in a 2 x 2 factorial design. A total of 6 heifers per treatment (3 each at 5 and 10 mo of age) were slaughtered for mammary tissue analysis. Remaining heifers were bred to evaluate impact of treatment on subsequent milk yield and composition. Mammary parenchymal growth was not affected by RUP or bST treatment. Total parenchymal mass increased from 16 to 364 g, and parenchymal DNA from 58 to 1022 mg from 3 to 10 mo of age, respectively. Furthermore, number of mammary epithelial cells likely was not affected by diet or bST because the epithelial cell proliferation index, assessed by Ki-67 labeling, was not affected by treatment, nor was total parenchymal DNA and lipid content. Neither deleterious effects of increased rates of gain nor positive effects of bST were evident in prepubertal mammary growth. Subsequent milk production and composition was not different among treatments.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fang Qiliang; Herczeg, Gregory J.; Rizzuto, Aaron

Past estimates for the age of the Upper Sco Association are typically 11–13 Myr for intermediate-mass stars and 4–5 Myr for low-mass stars. In this study, we simulate populations of young stars to investigate whether this apparent dependence of estimated age on spectral type may be explained by the star formation history of the association. Solar and intermediate mass stars begin their pre-main sequence evolution on the Hayashi track, with fully convective interiors and cool photospheres. Intermediate-mass stars quickly heat up and transition onto the radiative Henyey track. As a consequence, for clusters in which star formation occurs on amore » timescale similar to that of the transition from a convective to a radiative interior, discrepancies in ages will arise when ages are calculated as a function of temperature instead of mass. Simple simulations of a cluster with constant star formation over several Myr may explain about half of the difference in inferred ages versus photospheric temperature; speculative constructions that consist of a constant star formation followed by a large supernova-driven burst could fully explain the differences, including those between F and G stars where evolutionary tracks may be more accurate. The age spreads of low-mass stars predicted from these prescriptions for star formation are consistent with the observed luminosity spread of Upper Sco. The conclusion that a lengthy star formation history will yield a temperature dependence in ages is expected from the basic physics of pre-main sequence evolution, and is qualitatively robust to the large uncertainties in pre-main sequence evolutionary models.« less

Radiocarbon dating of individual lignin phenols: a new approach for establishing chronology of late quaternary lake sediments.

PubMed

Hou, Juzhi; Huang, Yongsong; Brodsky, Corynn; Alexandre, Marcelo R; McNichol, Ann P; King, John W; Hu, Feng Sheng; Shen, Ji

2010-09-01

The reliability of chronology is a prerequisite for meaningful paleoclimate reconstructions from sedimentary archives. The conventional approach of radiocarbon dating bulk organic carbon in lake sediments is often hampered by the old carbon effect, i.e., the assimilation of ancient dissolved inorganic carbon (DIC) derived from carbonate bedrocks or other sources. Therefore, radiocarbon dating is ideally performed on organic compounds derived from land plants that use atmospheric CO(2) and rapidly delivered to sediments. We demonstrate that lignin phenols isolated from lake sediments using reversed phase high performance liquid chromatography (HPLC) can serve as effective (14)C dating materials for establishing chronology during the late Quaternary. We developed a procedure to purify lignin phenols, building upon a published method. By isolating lignin from standard wood reference substances, we show that our method yields pure lignin phenols and consistent ages as the consensus ages and that our procedure does not introduce radiocarbon contamination. We further demonstrate that lignin phenol ages are compatible with varve counted and macrofossil dated sediment horizons in Steel Lake and Fayetteville Green Lake. Applying the new method to lake sediment cores from Lake Qinghai demonstrates that lignin phenol ages in Lake Qinghai are consistently younger than bulk total organic carbon (TOC) ages which are contaminated by old carbon effect. We also show that the age offset between lignin and bulk organic carbon differs at different Lake Qinghai sedimentary horizons, suggesting a variable hard water effect at different times and that a uniform age correction throughout the core is inappropriate.

Geology and ground-water resources of the upper Lodgepole Creek drainage basin, Wyoming, with a section on chemical quality of the water

USGS Publications Warehouse

Bjorklund, Louis Jay; Krieger, R.A.; Jochens, E.R.

1959-01-01

The principal sources of ground-water supply in the upper Lodgepole Creek drainage basin-the part of the basin west of the Wyoming-Nebraska State line-are the Brule formation of Oligocene age, the Arikaree formation of Miocene age, the Ogallala formation of Pliocene age, and the unconsolidated deposits of Quaternary age. The Brule formation is a moderately hard siltstone that generally is not a good aquifer. However, where it is fractured or where the upper part consists of pebbles of reworked siltstone, it will yield large quantities of water to wells. Many wells in the Pine Bluffs lowland, at the east end of the area, derive water from the Brule. The Arikaree formation, which consists of loosely to moderately cemented fine sand, will yield small quantities of water to wells but is not thick enough or permeable enough to supply sufficient water for irrigation. Only a few wells derive water from it. The Ogallala formation consists of lenticular beds of clay, silt, sand, and gravel which, in part, are cemented with calcium carbonate. Only the lower part of the formation is saturated. Nearly all the wells in the upland part of the area tap the Ogallala, but they supply water in amounts sufficient for domestic and stock use only. Two of the wells have a moderately large discharge, and other wells of comparable discharge probably could be drilled in those parts of the upland where the saturated part of the Ogallala is fairly thick. Most of the unconsolidated deposits of Quaternary age are very permeable and, where a sufficient thickness is saturated, will yield large quantities of water to wells. These deposits are a significant source of water supply in the southeastern part of the area. The Chadron formation of Oligocene age, which underlies the Brule formation, is a medium- to coarse-grained sandstone where it crops out in the Islay lowland. No wells tap the Chadron, but it probably would yield small quantities of water to wells. It lies at a relatively shallow depth beneath most of the Islay lowland, near the west end of the area, and at a depth of about 800 feet beneath the Pine Bluffs lowland. In the latter area it probably is finer grained and may not be permeable enough to yield water to wells. All the ground water in the area is derived from precipitation. It is estimated that about 5 percent of the precipitation infiltrates directly to the zone of saturation. The remainder either is evaporated immediately; is retained by the soil, later to be evaporated or transpired; or is discharged by overland flow to the surface drainage courses. Most of the water that reaches the surface drainage courses eventually sinks to the zone of saturation or is evaporated. The slope of the water table and the movement of ground water are generally eastward. The depth to water ranges from less than 10 feet in parts of the valley to about 300 feet in the upland areas. In much of the Pine Bluffs lowland, the depth to water is less than 50 feet. Ground water not pumped from wells within the area is discharged by evapotranspiration where the water table is close to the land surface, by outflow into streams, or by underflow eastward beneath the State line. The chemical quality of ground water from the principal sources is remarkably uniform, and the range in concentration of dissolved constituents is narrow. In general, the water is of the calcium bicarbonate type, is hard (hardness as CaC03 is as high as 246 ppm), and contains less than about 400 parts per million of dissolved solids, which is a moderate mineralization. Silica constitutes a large proportion of the dissolved solids. The water is suitable for irrigation and, except for iron in water from some wells that tap the Ogallala formation, meets the drinking water standards of the U.S. Public Health Service for chemical constituents. Because the water is siliceous, alkaline, and hard, it is unsuitable for many industrial uses unless treated.

Zircon U-Pb ages and Hf-O isotopic composition of migmatites from the Zanjan-Takab complex, NW Iran: Constraints on partial melting of metasediments

NASA Astrophysics Data System (ADS)

Moghadam, Hadi Shafaii; Li, Xian-Hua; Stern, Robert J.; Ghorbani, Ghasem; Bakhshizad, Farzaneh

2016-01-01

We study migmatites and other metamorphic rocks in the Zanjan-Takab region of NW Iran and use these results to report the first evidence of Oligocene core complex formation in Iran. Four samples of migmatites associated with paragneisses, including leucosomes and associated para-amphibolite melanosomes were selected for U-Pb dating and Hf-O isotopic analysis. Zircon cores - interpreted as originally detrital zircons - have variable ages that peak at ca. 100-110 Ma, but their sedimentation age - indicated by the youngest 206Pb/238U ages - is ca. 35-40 Ma. New zircons associated with incipient melting occur as overgrowths around zircon cores and/or as newly grown grains. Morphologies and internal structures suggest that rim growth and formation of new zircons were associated with partial melting. All four samples contain zircons with rims that yield 206Pb/238U ages of 28-25 Ma, indicating that partial melting occurred in Late Oligocene time. δ18O values for zircon rims vary between 8.2 and 12.3‰, significantly higher than expected for mantle inputs (δ18O 6‰) and consistent with equilibrium with surface materials. Zircon rims yield εHf(t) between 2.2 and 12.4 and two-stage Hf model ages of 448-562 Ma, indicating that the region is underlain by Cadomian-Caledonian crust. According to the Hf-O isotopic values, the main mechanism forming zircon rims was dissolution of pre-existing detrital zircons with reprecipitation of new zircon shortly thereafter. Oligocene ages indicate that partial melting accompanied core complex formation in the Zanjan-Takab region. Extension, melting, and core complex formation in south-central Iran are Eocene in age, but younger ages of Oligocene-Miocene in NW Iran and Turkey indicate that extension was distributed throughout the region during Cenozoic time.

Luminescence dating of the barrier spit at Chilika Lake, Orissa, India.

PubMed

Murray, A S; Mohanti, M

2006-01-01

Optically stimulated luminescence dating has been used to investigate the chronological development of the outer barrier spit forming Chilika Lake (Orissa, India), the largest brackish-water lagoon in Asia. Sixteen samples were examined, and these yielded equivalent doses of between 153 +/- 3 mGy and 2.23 +/- 0.07 Gy, corresponding to ages from approximately 40 y at the top of the spit to approximately 300 y at the bottom. The youngest ages are consistent with the age of the overlying vegetation, and modern material taken from the sub-tidal beach gave a dose of 4 +/- 2 mGy (corresponding to an age of 0.7 +/- 0.4 y), confirming that any previous potential luminescence signal in the source sediment is completely set to zero before incorporation into the spit. A clearly defined period of >2.5 m of barrier construction approximately 40 y ago is identified; prior to that the deposition rate was relatively constant for approximately 300 y.

Tensile properties to 650 C and deformation structures in a precipitation strengthened titanium-aluminum alloy

NASA Technical Reports Server (NTRS)

Mendiratta, M. G.

1973-01-01

Appreciable strength levels were retained to 650 C in a Ti-10Al-1Si alloy aged in the (alpha + alpha sub 2) phase field to yield optimum room temperature strength and ductility. The aging treatment precipitated a uniform distribution of alpha sub 2-particles such that, at room temperature, dislocations bypassed instead of shearing the particles at low strains. Specimens fractured at room temperature exhibited fine uniform dimples even for those aging conditions that imparted no macroscopic ductility. The main crack appeared to propagate through the planar slip bands that had cut through the alpha sub 2-particles. A two-step aging process produced a higher volume fraction of bimodally distributed alpha sub 2-particles that led to higher strength levels at elevated temperatures. Both for the single size and the bimodal alpha sub 2-particle distributions, elevated-temperature deformation structures consisted mainly of planar slip bands that sheared through the alpha sub 2-particles.

Effect of Plant Age on the Quantity and Quality of Proteins Extracted from Sugar Beet (Beta vulgaris L.) Leaves.

PubMed

Kiskini, Alexandra; Vissers, Anne; Vincken, Jean-Paul; Gruppen, Harry; Wierenga, Peter Alexander

2016-11-09

Effects of the developmental stage (e.g., young, mature, or senescent) of leaves on their chemical composition have been described in the literature. This study focuses on the variation in chemical composition and quantity and quality of proteins extracted from leaves due to variation in plant age (i.e., harvesting time), using leaves from sugar beets grown in a field (Rhino, Arrival) and in a greenhouse (Isabella). Within the same variety (Rhino, field; Arrival, field; Isabella, greenhouse) the protein content was similar for leaves from young and old plants (22 ± 1, 16 ± 1, and 10 ± 3% w/w db, respectively). Variation in final protein isolation yield was mostly due to variation in nitrogen extractability (28-56%), although no consistent correlation with plant age was found. A significant effect of plant age was observed on the quality (color) of the extracted protein, that is, brown (indicative of polyphenol oxidase activity) and yellow for extracts from old and young plants, respectively.

Discordances between follicle stimulating hormone (FSH) and anti-Müllerian hormone (AMH) in female infertility

PubMed Central

2010-01-01

Background Follicle stimulating hormone (FSH) and anti-Müllerian hormone (AMH) represent the two most frequently utilized laboratory tests in determining ovarian reserve (OR). This study determined the clinical significance of their concordance and discordance in female infertility patients. Methods We investigated 366 consecutive infertility patients (350 reached IVF), excluding women with polycystic ovarian syndrome (PCOS). They were considered to have normal FSH and AMH if values fell within age-specific (as-) 95% confidence intervals (CI), and to suffer from diminished ovarian reserve (DOR) if FSH exceeded and/or AMH fell below those. The two hormones, thus, could be concordant (Group I), both normal (IA) or abnormal (IB), show normal AMH/abnormal FSH (Group II) or normal FSH/abnormal AMH (Group III). Oocyte yields, stratified for age categories, were then studied in each group as reflection of OR. Results Oocyte yields significantly decreased from groups IA to II to III and IB. Predictive values of as-FSH/AMH patterns changed, however, at different ages. Except at very young and very old ages, normal as-AMH better predicted higher oocytes yields than normal as-FSH, though above age 42 years normal as-FSH predicts good oocyte yields even with abnormally low AMH. Under age 42 discrepancies between as- FSH and as-AMH remain similarly predictive of oocyte yields at all ages. Discussion Concordances and discordances between as-FSH and as-AMH improve OR assessments and predictability of oocyte yields in IVF. PMID:20565808

Water-supply potential from an asphalt-lined catchment near Holualoa Kona, Hawaii

USGS Publications Warehouse

Chinn, Salwyn S.W.

1965-01-01

The Jenkins-Whitesburg area includes approximately 250 square miles In Letcher and Pike Counties in the southeastern part of the Eastern Coal Field. In this area ground water is the principal source of water for nearly all rural families, most public supplies, several coal mines and coal processing plants, and one bottling plant. The major aquifers in the Jenkins-Whitesburg area are the Breathitt and Lee Formations of Pennsylvanian age. Other aquifers range in age from Devonian to Quaternary but are not important in this area because they occur at great depth or yield little or no water. The Breathitt Formation occurs throughout the area except along the crest and slopes of Pine Mountain and where it is covered by unconsolidated material of Quaternary age. The Breathitt Formation consists of shale, sandstone, and lesser amounts of coal and associated underclay. The yield of wells penetrating the Breathitt Formation ranges from less than 1 to 330 gallons per minute. Well yield is controlled by the type and depth of well, character of the aquifer, and topography of the well site. Generally, deep wells drilled in valleys of perennial streams offer the best potential for high yields. Although enough water for a minimum domestic supply (more than 100 gallons per day) may be obtained from shale, all high-yielding wells probably obtain water from vertical joints and from bedding planes which are best developed in sandstone. About 13 percent of the wells inventoried in the Breathitt Formation failed to supply enough water for a minimum domestic supply. Most of these are shallow dug wells or drilled wells on hillsides or hilltops. Abandoned coal mines are utilized as large infiltration galleries and furnish part of the water for several public supplies. The chemical quality of water from the Breathitt Formation varies considerably from place to place, but the water generally is acceptable for most domestic and industrial uses. Most water is a calcium magnesium bicarbonate or sodium bicarbonate type, and nearly all sampled water contained enough iron to stain cooking and laundry utensils. The water ranged from soft to very hard, and only one well in the Breathitt Formation produced salty water. The absence of salty water may be due to abundant fractures which are associated with the Pine Mountain fault and which have allowed fresh water to enter the formation. The Lee Formation underlies the Cumberland Mountain section and is exposed along the crest and southeast slope of Pine Mountain. The Lee Formation consists of massive sandstone and conglomerate with thin beds of shale and a few thin coal seams. Although the Lee Formation is tapped by only a few wells in this area, it is potentially an important aquifer. Wells penetrating the Lee Formation in the Cumberland Mountain section would probably yield water under artesian pressure. Unlike most water from the Lee Formation in other part.3 of eastern Kentucky, all water from the Lee Formation in the Jenkins-Whitesburg area is fresh. All water from the Lee Formation contained more than 0.3 parts per million of iron and ranged from soft to moderately hard.

Water-resources reconnaissance of the Ouachita Mountains, Arkansas

USGS Publications Warehouse

Albin, Donald R.

1965-01-01

The Jenkins-Whitesburg area includes approximately 250 square miles in Letcher and Pike Counties in the southeastern part of the Eastern Coal Field. In this area ground water is the principal source of water for nearly all rural families, most public supplies, several coal mines and coal processing plants, and one bottling plant. The major aquifers in the Jenkins-Whitesburg area are the Breathitt and Lee Formations of Pennsylvanian age. Other aquifers range in age from Devonian to Quaternary but are not important in this area because they occur at great depth or yield little or no water. The Breathitt Formation occurs throughout the area except along the crest and slopes of Pine Mountain and where it is covered by unconsolidated material of Quaternary age. The Breathitt Formation consists of shale, sandstone, and lesser amounts of coal and associated underclay. The yield of wells penetrating the Breathitt Formation ranges from less than 1 to 330 gallons per minute. Well yield is controlled by the type and depth of well, character of the aquifer, and topography of the well site. Generally, deep wells drilled in valleys of perennial streams offer the best potential for high yields. Although enough water for a minimum domestic supply (more than 100 gallons per day) may be obtained from shale, all high-yielding wells probably obtain water from vertical joints and from bedding planes which are best developed in sandstone. About 13 percent of the wells inventoried in the Breathitt Formation failed to supply enough water for a minimum domestic supply. Most of these are shallow dug wells or drilled wells on hillsides or hilltops. Abandoned coal mines are utilized as large infiltration galleries and furnish part of the water for several public supplies. The chemical quality of water from the Breathitt Formation varies considerably from place to place, but the water generally is acceptable for most domestic and industrial uses. Most water is a calcium magnesium bicarbonate or sodium bicarbonate type, and nearly all sampled water contained enough iron to stain cooking and laundry utensils. The water ranged from soft to very hard, and only one well in the Breathitt Formation produced salty water. The absence of salty water may be due to abundant fractures which are associated with the Pine Mountain fault and which have allowed fresh water to enter the formation. The Lee Formation underlies the Cumberland Mountain section and is exposed along the crest and southeast slope of Pine Mountain. The Lee Formation consists of massive sandstone and conglomerate with thin beds of shale and a few thin coal seams. Although the Lee Formation is tapped by only a few wells in this area, it is potentially an important aquifer. Wells penetrating the Lee Formation in the Cumberland Mountain section would probably yield water under artesian pressure. Unlike most water from the Lee Formation in other parts of eastern Kentucky, all water from the Lee Formation in the Jenkins-Whitesburg area is fresh. All water from the Lee Formation contained more than 0.3 parts per million of iron and ranged from soft to moderately hard.

Yield and proliferation rate of adipose-derived stromal cells as a function of age, body mass index and harvest site-increasing the yield by use of adherent and supernatant fractions?

PubMed

Buschmann, Johanna; Gao, Shuping; Härter, Luc; Hemmi, Sonja; Welti, Manfred; Werner, Clement M L; Calcagni, Maurizio; Cinelli, Paolo; Wanner, Guido A

2013-09-01

Adipose-derived stem cells are easily accessed and have a relatively high density compared with other mesenchymal stromal cells. Isolation protocols of adipose-derived stem cells (ASC) rely on the cell's ability to adhere to tissue culture plastic overnight. It was evaluated whether the floating ASC fractions are also of interest for cell-based therapies. In addition, the impact of age, body mass index (BMI) and harvest site was assessed. The surface protein profile with the use of flow cytometry, the cell yield and the doubling time of passages 4, 5 and 6 of ASC from 30 donors were determined. Adherent and supernatant fractions were compared. The impact of age, BMI and harvest site on cell yield and doubling times was determined. Both adherent and supernatant fractions showed high mean fluorescence intensities for CD13, CD29, CD44, CD73, CD90 and CD105 and comparatively low mean fluorescence intensities for CD11b, CD62L, intracellular adhesion molecule-1 and CD34. Doubling times of adherent and supernatant fractions did not differ significantly. Whereas the old age group had a significantly lower cell yield compared with the middle aged group, BMI and harvest site had no impact on cell yield. Finally, doubling times for passages 4, 5 and 6 were not influenced by the age and BMI of the donors, nor the tissue-harvesting site. The floating ASC fraction is an equivalent second cell source just like the adherent ASC fraction. Donor age, BMI and harvest site do not influence cell yield and proliferation rate. Copyright © 2013 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

Dietary diversity and nutritional status among children in rural Burkina Faso.

PubMed

Sié, Ali; Tapsoba, Charlemagne; Dah, Clarisse; Ouermi, Lucienne; Zabre, Pascal; Bärnighausen, Till; Arzika, Ahmed M; Lebas, Elodie; Snyder, Blake M; Moe, Caitlin; Keenan, Jeremy D; Oldenburg, Catherine E

2018-05-01

Burkina Faso has a seasonal malnutrition pattern, with higher malnutrition prevalence during the rainy season when crop yields are low. We investigated the association between dietary diversity and nutritional status among children aged 6-59 mo during the low crop yield season in rural Burkina Faso to assess the role of dietary diversity during the lean season on childhood nutritional status. Caregivers reported the dietary diversity of the past 7 d, consisting of 11 food groups, summed into a scale. Anthropometric measurements were taken from all children. Height-for-age (HAZ), weight-for-height (WHZ) and weight-for-age (WAZ) z-scores were calculated based on 2006 WHO standards. Stunting, wasting and underweight were defined as HAZ, WHZ and WAZ <-2 SD, respectively. Multivariable regression models adjusting for potential confounders including household food insecurity and animal ownership were used to assess the relationship between anthropometric indices and dietary diversity. Of 251 children enrolled in the study, 20.6% were stunted, 10.0% wasted and 13.9% underweight. Greater dietary diversity was associated with greater HAZ (SD 0.14, 95% CI 0.04 to 0.25) among all children. There was no association between dietary diversity and wasting or mid-upper arm circumference in this study. Increasing dietary diversity may be an approach to reduce the burden of stunting and chronic malnutrition among young children in regions with seasonal food insecurity.

Magmatic microgranular enclaves of the northeast of Mato Grosso, Brazil, SE Amazonian Craton: Insights into the magmatism of the Uatumã Supergroup on the basis of field and petrological data

NASA Astrophysics Data System (ADS)

Tarelow Neto, João; Pierosan, Ronaldo; Barros, Márcia Aparecida de Sant'Ana; Chemale, Farid, Jr.; Santos, Fernanda Silva

2017-10-01

Felsic and mafic microgranular enclaves occurs hosted in Paleoproterozoic felsic volcanic and plutonic rocks of the Iriri Group and Rio Dourado Intrusive Suite that crop out in the northeast of the Brazilian state of Mato Grosso as part of the Uatumã Supergroup in the SE Amazonian Craton. The volcanic rocks consist of dacites, rhyolites and ignimbrites of the Iriri Group among which dacites yielded a crystallization age of 1895 ± 7 Ma. The granitoids are composed of syenogranites, and monzogranites along with subordinate granodiorites. The granite pluton of syenogranite composition belongs to the Rio Dourado Intrusive Suite and was previously dated at 1876 ± 39 Ma. Mafic enclaves show petrographic features that suggest magma mingling processes and may be classified as olivine-clinopyroxene gabbro, clinopyroxene-hornblende gabbro, biotite-clinopyroxene diorite, biotite-hornblende diorite, and biotite-quartz diorite. Geochemical patterns of dioritic enclaves fit with those of the mafic rocks of the Santa Inês Intrusive Suite and suggest that they are comagmatic. The felsic enclaves consist of quartz monzonites, monzogranites and quartz-rich granitoids, with geochemical patterns and ages compatible with those of the Iriri Group. U-Pb dating of a granodioritic enclave hosted by a syenogranite of the Rio Dourado Intrusive Suite yielded three distinct ages: a Paleoproterozoic magmatic age around 1.87 Ga; a Paleoproterozoic inherited age of 2001 ± 7 Ma; and Neoarchean inherited ages ranging from 2512 to 2767 Ma. The felsic enclaves may have been derived from crustal melts, and contain restitic zircon grains, or chilled margins with zircon removed from the wall rocks. The recognition of diverse geochemical patterns of felsic and mafic enclaves suggests that the study area can represent the top of a shallow complex magma chamber that experienced a number of different replenishment events from diverse sources. The mafic enclaves and their coeval enclosing volcanic rocks suggest that the Uatumã Supergroup felsic magmatism and the Santa Inês mafic magmatism could be contemporaneous. In confirming that, this assumption would allow us to recognize a bimodal character of the Uatumã magmatism in the study area as well as the important role that mantle melts played on its genesis.

Yield comparisons from even-aged and uneven-aged loblolly-shortleaf pine stands

Treesearch

James M. Guldin; James B. Baker

1988-01-01

Empirical yields for a 36-year management period are presented for seven long-term studies on similar sites in loblolly-shortleaf pine (Pinus taeda L.-P. echinata Mill.) stands on the upper southern coastal plain of southern Arkansas and northern Louisiana. Total merchantable cubic-fooy yields are highest for conventionally...

Associations between strain, herd size, age at first calving, culling reason and lifetime performance characteristics in Holstein-Friesian cows.

PubMed

Adamczyk, K; Makulska, J; Jagusiak, W; Węglarz, A

2017-02-01

Cow longevity and lifetime performance traits are good indicators of breeding effectiveness and animal welfare. They are also interrelated with the economics of dairy herd. Unfortunately, a high milk yield is often associated with deteriorated cow health and fertility and, consequently, with an increased culling rate. This situation, observed also in the Polish population of Holstein-Friesian cattle, inspired us to undertake a study on the associations between some factors and lifetime performance characteristics. The data set consisted of the records on 135 496 cows, including 131 526 of the Black and White strain (BW), and 3970 of the Red and White strain (RW) covered by performance recording and culled in 2012. It was found that cows of the BW strain and those from the largest herds (>100 cows) reached higher lifetime and mean daily energy-corrected milk (ECM) yields than cows of the RW strain and those from smaller herds culled at a similar age. Cows youngest at first calving (<2.0 years) were characterised by the highest lifetime ECM yield. It indicates that heifers can be bred even when they are younger than 15 to 16 months with no significant negative effect on their later performance. Infertility and reproduction problems (39.6%) and udder diseases (15.5%) constituted the most frequent reasons for cow culling. Cow longevity and lifetime productivity were considerably affected by the interactions between the studied factors.

Investigation of Strain Aging in the Ordered Intermetallic Compound beta-NiAl. Ph.D. Thesis Final Contractor Report

NASA Technical Reports Server (NTRS)

Weaver, Mark Lovell

1995-01-01

The phenomenon of strain aging has been investigated in polycrystalline and single crystal NiAl alloys at temperatures between 300 and 1200 K. Static strain aging studies revealed that after annealing at 1100 K for 7200 s (i.e., 2h) followed by furnace cooling, high purity, nitrogen-doped and titanium-doped polycrystalline alloys exhibited continuous yielding, while conventional-purity and carbon-doped alloys exhibited distinct yield points and Luders strains. Prestraining by hydrostatic pressurization removed the yield points, but they could be reintroduced by further annealing treatments. Yield points could be reintroduced more rapidly if the specimens were prestrained uniaxially rather than hydrostatically, owing to the arrangement of dislocations into cell structures during uniaxial deformation. The time dependence of the strain aging events followed at t(exp 2/3) relationship suggesting that the yield points observed in polycrystalline NiAl were the result of the pinning of mobile dislocations by interstitials, specifically carbon. Between 700 and 800 K, yield stress plateaus, yield stress transients upon a ten-fold increase in strain rate, work hardening peaks, and dips in the strain rate sensitivity (SRS) have been observed in conventional-purity and carbon-doped polycrystals. In single crystals, similar behavior was observed; in conventional-purity single crystals, however, the strain rate sensitivity became negative resulting in serrated yielding, whereas, the strain rate sensitivity stayed positive in high purity and in molybdenum-doped NiAl. These observations are indicative of dynamic strain aging (DSA) and are discussed in terms of conventional strain aging theories. The impact of these phenomena on the composition-structure-property relations are discerned. Finally, a good correlation has been demonstrated between the properties of NiAl alloys and a recently developed model for strain aging in metals and alloys developed by Reed-Hill et al.

A New Look at the Magnetostratigraphy and Paleomagnetism of the Upper Triassic to Lower Jurassic Moenave Formation, St. George Area, Southwestern Utah.

NASA Astrophysics Data System (ADS)

Donohoo-Hurley, L. L.; Geissman, J. W.; Lucas, S. G.; Roy, M.

2006-12-01

Paleomagnetic data from rocks exposed on and off the Colorado Plateau provide poles that young westward during the Late Triassic (to about 52^{O} E longitude) and young eastward during the Early Jurassic. This pattern has been used to posit the existence of a J-1 cusp in the North American APW path at the Triassic- Jurassic boundary (TJB), at about 199.6 Ma. Considerable debate has focused on the morphology and placement of the J-1 cusp due to poorly exposed and/or incompletely sampled sections, debates about the magnitude of Colorado Plateau rotation, and disagreements regarding stratigraphic relationships. Red beds of the Whitmore Point (~25 m of mostly lacustrine deposits) and Dinosaur Canyon (~55 m of hematitic fluvial sandstones and siltstones) members of the Moenave Formation (MF) are inferred to have been deposited across the TJB based on palynostratigraphy and vertebrate biostratigraphy. Two previously unsampled sections (Leeds and Warner Valley) of the MF are well exposed near St. George, Utah, and located in the transition zone that defines the western boundary of the Colorado Plateau. Preliminary data from samples collected from the Whitmore Point and Dinosaur Canyon members yield exclusively normal polarity magnetizations, which is consistent with previous studies and the normal polarity TJB magnetozone. Thermal demagnetization response suggests that the remanence is carried mainly in hematite. The degree of hematite pigmentation varies in both sections, and several Leeds sites show a weak overprint component that unblocks by 400^{O}-450^{O} C, with a higher unblocking temperature components, consistent with an Early Triassic Late Jurassic age that fully unblock around 670^{O}-680^{O} C. Individual beds (treated as specific sites) in part of the Dinosaur Canyon Member yield site mean directions with declinations between about 020 and 030, and may define the easternmost position (i.e. 60-50^{O} E latitude) of the NAMAPW path and thus the approximate the TJB. This interpretation is consistent with recent biostratigraphic arguments that the TJB lies in the upper part of the Dinosaur Canyon Member. The Whitmore Point Member yields more north-directed declinations, suggesting an earliest Jurassic (post-cusp) age. It is likely that more complete data from these and related sections will provide a further refinement of the stratigraphic placement of the TJB and the geometry of the J-1 cusp.

Identification of saline soils with multi-year remote sensing of crop yields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lobell, D; Ortiz-Monasterio, I; Gurrola, F C

2006-10-17

Soil salinity is an important constraint to agricultural sustainability, but accurate information on its variation across agricultural regions or its impact on regional crop productivity remains sparse. We evaluated the relationships between remotely sensed wheat yields and salinity in an irrigation district in the Colorado River Delta Region. The goals of this study were to (1) document the relative importance of salinity as a constraint to regional wheat production and (2) develop techniques to accurately identify saline fields. Estimates of wheat yield from six years of Landsat data agreed well with ground-based records on individual fields (R{sup 2} = 0.65).more » Salinity measurements on 122 randomly selected fields revealed that average 0-60 cm salinity levels > 4 dS m{sup -1} reduced wheat yields, but the relative scarcity of such fields resulted in less than 1% regional yield loss attributable to salinity. Moreover, low yield was not a reliable indicator of high salinity, because many other factors contributed to yield variability in individual years. However, temporal analysis of yield images showed a significant fraction of fields exhibited consistently low yields over the six year period. A subsequent survey of 60 additional fields, half of which were consistently low yielding, revealed that this targeted subset had significantly higher salinity at 30-60 cm depth than the control group (p = 0.02). These results suggest that high subsurface salinity is associated with consistently low yields in this region, and that multi-year yield maps derived from remote sensing therefore provide an opportunity to map salinity across agricultural regions.« less

Peer rejection, aggressive or withdrawn behavior, and psychological maladjustment from ages 5 to 12: an examination of four predictive models.

PubMed

Ladd, Gary W

2006-01-01

Findings yielded a comprehensive portrait of the predictive relations among children's aggressive or withdrawn behaviors, peer rejection, and psychological maladjustment across the 5-12 age period. Examination of peer rejection in different variable contexts and across repeated intervals throughout childhood revealed differences in the timing, strength, and consistency of this risk factor as a distinct (additive) predictor of externalizing versus internalizing problems. In conjunction with aggressive behavior, peer rejection proved to be a stronger additive predictor of externalizing problems during early rather than later childhood. Relative to withdrawn behavior, rejection's efficacy as a distinct predictor of internalizing problems was significant early in childhood and increased progressively thereafter. These additive path models fit the data better than did disorder-driven or transactional models.

The 190Pt-186Os Decay System Applied to Dating Platinum-Group Element Mineralization in Layered Intrusions, Ophiolites and Detrital Deposits

NASA Astrophysics Data System (ADS)

Coggon, J. A.; Nowell, G.; Pearson, G.; Oberthür, T.; Lorand, J.; Melcher, F.; Parman, S. W.

2010-12-01

Discrete platinum-group minerals (PGM) occur as accessory phases in mafic-ultamafic intrusions and ophiolitic chromitites, as well as numerous detrital deposits globally. The 190Pt-186Os decay system, measured by laser ablation MC-ICPMS (LA-MC-ICPMS) provides a useful geochronometric tool for direct dating of PGM. Here we present two examples that verify the accuracy of the technique in geologically well constrained situations and demonstrate the potential for using the 190Pt-186Os PGM method to accurately date layered mafic intrusions, ophiolitic chromitites and detrital PGM deposits. Fifty PGM grains from three different horizons within the Bushveld complex yield a Pt-Os isochron age of 2012 ± 47 Ma (2σ, MSWD = 1.19, 186Os/188Osi = 0.119818 ± 0.000006). This is consistent with the published U-Pb zircon age of 2054 Ma (Scoates and Friedman, 2008). The younger PGM isochron age is not likely to be a function of difference in blocking temperatures in the different systems. Pt-Os model ages are possible in high pt grains because initial 186Os/188Os can be well constrained. Using this approach we obtained Pt-Os model ages of 2113 ± 106 Ma and 2042 ± 102 Ma for a Bushveld Pt-Fe alloy and sperrylite respectively. Detrital PGM derived from the Meratus ophiolite, southeast Borneo yield a 190Pt-186Os isochron age of 202.5 Ma ± 8.3 Ma (2σ, n = 260, MSWD = 0.90, 186Os/188Osi = 0.119830 ± 0.000003), consistent with radiometric and biostratigraphic age constraints (Wakita et al., 1998). We interpret this as the age of formation of the PGM grains in during chromitite genesis in the lower oceanic lithosphere. Our combined data demonstrate the utility of the LA-MC-ICPMS method as a tool for accurate Pt-Os dating of detrital PGM as well as their igneous parent bodies. We can constrain Pt/Os fractionation at the ablation site as being < 2.5%, while within-grain heterogeneity is ultimately one of the strongest controls on isochron and single-grain ages given the partial sampling represented by laser ablation. Scoates, J.S. and Friedman, R.M. 2008. Precise age of the platiniferous Merensky reef, Bushveld Complex, South Africa, by the U-Pb zircon chemical abrasion ID-TIMS technique; Economic Geology 103, p. 465-471. Wakita, K., Miyazaki, K., Zulkarnain, I., Sopaheluwakan, J. and Sanyoto, P. 1998. Tectonic implications of new age data for the Meratus complex of south Kalimantan, Indonesia; Island Arc 7, p. 202-222.

Detrital zircon age and isotopic constraints on the provenance of turbidites from the southernmost part of the Beishan orogen, NW China

NASA Astrophysics Data System (ADS)

Guo, Q. Q.; Chung, S. L.; Lee, H. Y.; Xiao, W.; Hou, Q.; Li, S.

2017-12-01

The Altaids in Central and East Asia is one of the largest accretionary orogenic collages in the world. The Beishan orogen, linked the Tianshan and Xingmeng orogens, occupy a key position to trace the terminal processes of the Altaids. It comprises an assemblage of magmatic arcs and ophiolitic mélanges. The Permian clastic turbidites, situated between the Huaniushan arc and the Shibanshan arc, are the youngest reported deep-marine clasts in the Beishan orogen. They are separated into the Liuyuan turbidites (NT) to the north and the Heishankou turbidites (ST) to the south by the Liuyuan complex. Detrital zircon grains from the NT yielded a wide range, from 254-3111 Ma, with two age clusters at 273 Ma and 424 Ma, indicating they provenance from the Huaniushan arc to the north. Those from the ST yielded ages from 260-2209 Ma, with age clusters at 270 Ma, 295 Ma, 420 Ma and 878 Ma, indicating the provenance from the Shibanshan arc to the south. The youngest three grains from the NT yield a weighted mean age of 260 Ma and those from the ST an age of 255 Ma, indicating an End-Permian maximum depositional age. The Precambrian zircons of the NT have diverse ɛHf(t) values (-12.6 to +10.4), while those of the ST from -6 to -2.6, indicating distinguishing histories of their provenances. The NT have more positive ɛNd(t) values than the ST, suggesting more juvenile or less evolved crustal components in the source. Two contrasting provenances, together with data in the literature, define the latest suture in the Beishan region at 240-250 Ma. The younger peak of U-Pb analysis results of detrital zircons from the northern part of the final suture zone in the southern Altaids is younging eastward from 288 Ma to 247 Ma, which may characterize the closure of the Paleo-Asian Ocean from west to east in about 40 Ma. This identification of the latest suture in the southern Altaids provides new constraints on the Paleo-Asian Ocean - specifically the nature and timing of the end of the subduction - but also on the amalgamation of the super continental of Eurasia that consists of micro blocks with a variety of histories.

Costs and Benefits of Orthographic Inconsistency in Reading: Evidence from a Cross-Linguistic Comparison

PubMed Central

Marinelli, Chiara Valeria; Romani, Cristina; Burani, Cristina; McGowan, Victoria A.; Zoccolotti, Pierluigi

2016-01-01

We compared reading acquisition in English and Italian children up to late primary school analyzing RTs and errors as a function of various psycholinguistic variables and changes due to experience. Our results show that reading becomes progressively more reliant on larger processing units with age, but that this is modulated by consistency of the language. In English, an inconsistent orthography, reliance on larger units occurs earlier on and it is demonstrated by faster RTs, a stronger effect of lexical variables and lack of length effect (by fifth grade). However, not all English children are able to master this mode of processing yielding larger inter-individual variability. In Italian, a consistent orthography, reliance on larger units occurs later and it is less pronounced. This is demonstrated by larger length effects which remain significant even in older children and by larger effects of a global factor (related to speed of orthographic decoding) explaining changes of performance across ages. Our results show the importance of considering not only overall performance, but inter-individual variability and variability between conditions when interpreting cross-linguistic differences. PMID:27355364

Costs and Benefits of Orthographic Inconsistency in Reading: Evidence from a Cross-Linguistic Comparison.

PubMed

Marinelli, Chiara Valeria; Romani, Cristina; Burani, Cristina; McGowan, Victoria A; Zoccolotti, Pierluigi

2016-01-01

We compared reading acquisition in English and Italian children up to late primary school analyzing RTs and errors as a function of various psycholinguistic variables and changes due to experience. Our results show that reading becomes progressively more reliant on larger processing units with age, but that this is modulated by consistency of the language. In English, an inconsistent orthography, reliance on larger units occurs earlier on and it is demonstrated by faster RTs, a stronger effect of lexical variables and lack of length effect (by fifth grade). However, not all English children are able to master this mode of processing yielding larger inter-individual variability. In Italian, a consistent orthography, reliance on larger units occurs later and it is less pronounced. This is demonstrated by larger length effects which remain significant even in older children and by larger effects of a global factor (related to speed of orthographic decoding) explaining changes of performance across ages. Our results show the importance of considering not only overall performance, but inter-individual variability and variability between conditions when interpreting cross-linguistic differences.

Paleomagnetism of Proterozoic mafic dikes from the Tobacco Root Mountains, southwest Montana

USGS Publications Warehouse

Harlan, S.S.; Geissman, J. Wm; Snee, L.W.

2008-01-01

Paleomagnetic data from Proterozoic mafic dikes in southwestern Montana provides evidence for two distinct episodes of subparallel dike emplacement at ca. 1450 and 780 Ma. Published geochemical data from dikes in the southern Tobacco Root Mountains has identified three distinct compositional groups, termed groups A, B, and C. Geochronological data from the group A dikes yielded a Sm-Nd age of 1448 ?? 49 Ma. Emplacement of these dikes is thought to reflect mafic magmatism associated with extension accompanying development of the adjacent Mesoproterozoic Belt Basin. Paleomagnetic results from these dikes and a group C dike yield antipodal magnetizations with a group-mean direction of D = 225.0??, I = 61.8?? (k = 27.9, ??95 = 7.7??, N = 14 independent means/24 sites). The average paleomagnetic pole (8.7??N, 216.1??E, A95 = 10.3??) is considered to be primary on the basis of positive baked contact tests and similarity to poles of ca. 1.45-1.4 Ga from intrusions elsewhere in North America, but is discordant with respect to poles from age equivalent sedimentary rocks of the Meosoproterozoic Belt Supergroup. 40Ar/39Ar dates from geochemical group B dikes are consistent with published U-Pb dates that demonstrate dike emplacement at 780 Ma as part of the regional Gunbarrel magmatic event. Hornblende concentrates from the group B dikes yield 40Ar/39Ar apparent ages of 778-772 Ma, whereas biotite from a baked contact zone yielded a plateau date of 788 Ma. Paleomagnetic results from the group B dikes yield a mean direction of D = 301.5??, I = -17.1?? (k = 65.7, ??95 = 4.0??, N = 12 independent means/23 sites) with a paleomagnetic pole at 14.6??N, 127.0??E (A95 = 3.2??). The combination of geochronologic data, results of a baked contact test, and spatial agreement of the paleomagnetic poles with poles of similar age elsewhere in North America indicates that this is also a primary magnetization associated with dike emplacement. Paleomagnetic data from some of the Tobacco Root Mountains dikes provide evidence that they were partially to completely remagnetized during latest Cretaceous to early Tertiary time, perhaps due to thermal affects associated with emplacement of the Late Cretaceous Tobacco Root Batholith. The overall agreement of paleomagnetic poles from the Proterozoic dikes with those of age equivalent rocks elsewhere in North America and agreement of the secondary magnetization with expected directions for the latest Cretaceous/early Tertiary indicate that the rocks of the Tobacco Root Mountains have not experienced significant tilting or vertical axis rotation since the Mesoproterozoic. The new paleomagnetic poles from this study thus provide key data for refining Meso- and Neoproterozoic parts of the North American APW path. ?? 2008 Elsevier B.V. All rights reserved.

Cooling Models for Old White Dwarfs

NASA Astrophysics Data System (ADS)

Hansen, Brad M. S.

1999-08-01

We present new white dwarf cooling models that incorporate an accurate outer boundary condition based on new opacity and detailed radiative transfer calculations. We find that helium-atmosphere dwarfs cool considerably faster than has previously been claimed, while old hydrogen-atmosphere dwarfs will deviate significantly from blackbody appearance. We use our new models to derive age limits for the Galactic disk. We find that the Liebert, Dahn, & Monet luminosity function yields an age of only 6 Gyr if it is complete to stated limits. However, age estimates of individual dwarfs and the luminosity function of Oswalt et al. are both consistent with disk ages as large as ~11 Gyr. We have also used our models to place constraints on white dwarf dark matter in the Galactic halo. We find that previous attempts using inadequate cooling models were too severe and that direct detection limits allow a halo that is 11 Gyr old. If the halo is composed solely of helium-atmosphere dwarfs, the lower age limit is only 7.5 Gyr. We also demonstrate the importance of studying the cooling sequences of white dwarfs in globular clusters.

Modeling Fetal Weight for Gestational Age: A Comparison of a Flexible Multi-level Spline-based Model with Other Approaches

PubMed Central

Villandré, Luc; Hutcheon, Jennifer A; Perez Trejo, Maria Esther; Abenhaim, Haim; Jacobsen, Geir; Platt, Robert W

2011-01-01

We present a model for longitudinal measures of fetal weight as a function of gestational age. We use a linear mixed model, with a Box-Cox transformation of fetal weight values, and restricted cubic splines, in order to flexibly but parsimoniously model median fetal weight. We systematically compare our model to other proposed approaches. All proposed methods are shown to yield similar median estimates, as evidenced by overlapping pointwise confidence bands, except after 40 completed weeks, where our method seems to produce estimates more consistent with observed data. Sex-based stratification affects the estimates of the random effects variance-covariance structure, without significantly changing sex-specific fitted median values. We illustrate the benefits of including sex-gestational age interaction terms in the model over stratification. The comparison leads to the conclusion that the selection of a model for fetal weight for gestational age can be based on the specific goals and configuration of a given study without affecting the precision or value of median estimates for most gestational ages of interest. PMID:21931571

Cryogenic Fracture Toughness Improvement for the Super Lightweight Tank's Main Structural Alloy

NASA Technical Reports Server (NTRS)

Chen, P. S.; Stanton, W. P.

2002-01-01

Marshall Space Flight Center has developed a two-step (TS) artificial aging technique that can significantly enhance cryogenic fracture toughness and resistance to stress corrosion cracking (SCC) in aluminum-copper-lithium alloy 2195. The new TS aging treatment consists of exposures at 132 C (270 F)/20 hr + 138 C (280 F)/42 hr, which can be readily applied to flight hardware production. TS aging achieves the same yield strength levels as conventional aging, while providing much improved ductility in the short transverse direction. After TS aging, five previously rejected lots of alloy 2195 (lots 950M029B, 960M030F, 960M030J, 960M030K, and 960M030L) passed simulated service testing for use in the super lightweight tank program. Each lot exhibited higher fracture toughness at cryogenic temperature than at ambient temperature. Their SCC resistance was also enhanced. All SCC specimens passed the minimum 10-day requirement in 3.5-percent sodium chloride alternate immersion at a stress of 45 ksi. The SCC lives ranged from 57 to 83 days, with an average of 70 days.

Artificial Aging Effects on Cryogenic Fracture Toughness of the Main Structural Alloy for the Super Lightweight Tank

NASA Technical Reports Server (NTRS)

Chen, P. S.; Stanton, W. P.

2002-01-01

In 1996, Marshall Space Flight Center developed a multistep heating rate-controlled (MSRC) aging technique that significantly enhanced cryogenic fracture toughness (CFT) and reduced the statistical spread of fracture toughness values in alloy 2195 by controlling the location and size of strengthening precipitate T1. However, it could not be readily applied to flight-related hardware production, primarily because large-scale production furnaces are unable to maintain a heating rate of 0.6 C (1 F)/hr. In August 1996, a new program was initiated to determine whether the MSRC aging treatment could be further modified to facilitate its implementation to flight hardware production. It was successfully redesigned into a simplified two-step aging treatment consisting of 132 C (270 F)/20 hr + 138 C (280 F)/40 hr. Results indicated that two-step aging can achieve the same yield strength levels as those produced by conventional aging while providing greatly improved ductility. Two-step aging proved to be very effective at enhancing CFT, enabling previously rejected materials to meet simulated service requirements. Cryogenic properties are improved by controlling T1 nucleation and growth so that they are promoted in the matrix and suppressed in the subgrain boundaries.

The Comparison of Detrital Zircon Ages to Point Count Provenance Analysis for the Pottsville Sandstone in the Northern Appalachian Foreland Basin Venango County, Pennsylvania

NASA Astrophysics Data System (ADS)

Loveday, S.; Harris, D. B.; Schiappa, T.; Pecha, M.

2017-12-01

The specific sources of sediments deposited in the Appalachian basin prior to and immediately following the Alleghenian orogeny has long been a topic of debate. Recent advances in U-Pb dating of detrital zircons have greatly helped to determine some of the sources of these sediments. For this study, sandstone samples were collected from the Pottsville Formation in the northern Appalachian Foreland Basin, Venango County, Pennsylvania to provide supplementary data for previous work that sought to describe the provenance of the same sediments by point counts of thin sections of the same units. Results of this previous work established that the provenance for these units was transitional recycled orogenic, including multiple recycled sediments, and that a cratonic contribution was not able to be determined clearly. The previous results suggested that the paleoenvironment was a fluvial dominated delta prograding in the northern direction. However, no geochronologic data was found during this study to confirm this interpretation. We sought to verify these results by U-Pb analysis of detrital zircons. Samples were collected from the areas where the previous research took place. U-Pb ages were found from sample at the highest elevation and lowest elevation. In the first sample, sample 17SL01 (younger sample stratigraphically), the zircons yield U-Pb age range peaks at 442-468 ma and 1037-1081 ma. The probability density plot for this specific sample displays a complete age gap from 500 ma to 811 ma. In the second sample, sample 17SL03 (older rock stratigraphically), the zircons yield U-Pb ages range peaks of 424-616 ma and 975-1057 ma. This sample doesn't show any ages younger than 424 ma and it doesn't display the sample age gap as sample 17SL01 does. The ages of zircons are consistent with thin section point counting provenance results from previous research suggesting zircon transport from the northern direction.

The effect of age of cochlear implantation on vocal characteristics in children

PubMed Central

Knight, Kerry; Ducasse, Simone; Coetzee, Ashley; Louw, Anel

2016-01-01

Background Early cochlear implantation aids auditory feedback and supports better communication and self-monitoring of the voice. The objective of this study was to determine whether the age of cochlear implantation has an impact on vocal development in children implanted before age 4. Method and procedures The study consisted of 19 participants in total. All implant recipients (experimental group) were 3–5 years post-implantation, including four prelingual (0–2 years) and five perilingual (2–4 years) implant recipients. The control group consisted of 10 children whose hearing was within normal limits between the ages 3–6 years and 10 months, which was compared to the experimental group. Established paediatric norms were used for additional comparison. A questionnaire was used to gather information from each of the participant’s caregivers to determine whether other personal and contextual factors had an impact on voice production. An acoustic analysis was conducted for each participant using the Multi-Dimensional Voice Program of the Computerized Speech Lab. Results When the experimental group and the control group were compared, similar results were yielded for fundamental frequency and short-term perturbation (jitter and shimmer). More variability was noted in long-term frequency and amplitude measures, with significantly higher differences, and therefore further outside the norms, in the prelingual group when compared to the perilingual and control groups. Conclusion In this study, age of implantation did not impact vocal characteristics. Further research should include larger sample sizes, with participants that are age and gender matched. PMID:27380914

The tectonothermal evolution of the Venezuelan Caribbean Mountain System: 40Ar/39Ar age insights from a Rodinian-related rock, the Cordillera de la Costa and Margarita Island

NASA Astrophysics Data System (ADS)

Fournier, Herbert W.; Lee, James K. W.; Urbani, Franco; Grande, Sebastián

2017-12-01

The Caribbean Mountain System in Venezuela contains rocks formed at high-pressure/low-temperature (HP/LT) conditions by the Cretaceous-Paleocene oblique collision occurred between the Caribbean and South American plates and involving Rodinian-related blocks. 40Ar/39Ar dating of rocks from the Cordillera de la Costa and Margarita Island has constrained key pre- and syntectonothermal events associated with the emplacement of this system. In a Rodinian marble, two phlogopite crystals of different grain sizes yield plateau ages of 888 ± 4 Ma and 874 ± 4 Ma. These results are interpreted as cooling ages after a major anorthosite-mangerite-charnockite-granite-suite intrusion at 920 Ma related to the break-up of Rodinia along the Amazonian-Baltica collisional zone - the Putumayo Orogen. Current plate reconstructions during the Neoproterozoic and previous age results indicate a correlation between the anorthositic complexes located in northwestern Venezuela (Yumare Complex) and southern Norway (Rogaland Complex), suggesting a similar tectonic setting during orogenic relaxation along the Amazonian and Baltica suture. A temperature-time path based on calculated Ar-closure temperatures of phlogopite indicates rapid cooling of 14 ± 4 °C Ma-1 from 920 Ma to 888 Ma, and a very slow to almost isothermal cooling of 4 ± 2 °C Ma-1 from 888 Ma to 874 Ma. On Margarita Island, magnesiohornblende and (alumino) barroisite from HP/LT rocks and muscovite from a leucocratic rock that was intruded before the HP/LT event yield identical ages within error at c. 54-47 Ma, consistent with previous dating results across the island utilizing different isotopic systems. The close association of these rocks and the Manzanillo Shear Zone indicates a main pathway for Ca-rich, 40Ar-free and hot fluids that locally raised the ambient T of the already exhumed and juxtaposed rock units. These fluids crystallized new hornblende and muscovite and thermally reset barroisite. This fluid activity event is 5 Ma younger than the last magmatic activity in the Aves Arc (c. 59 Ma) along its southern edge and related to the opening of the Grenada Basin. In the Cordillera de la Costa, magnesiohornblende, phengite, magnesian siderophyllite, ferroan phlogopite and K-feldspar from rock units of the Carayaca and Ávila terranes yield a wide range of ages (275-20 Ma). The oldest ages (275 Ma and 120 Ma) obtained from the Caruao Metatonalite suggest at least two thermal events at these times and are in agreement with the amalgamation of Pangaea and fluid infiltration, respectively. The remaining ages (35-20 Ma) are consistent with previous results and reflect short-lived fluid infiltrations related to tectonothermal events. A phengite age of 35 Ma from an omphacitite lens in the Antímano Marble of the Carayaca Terrane indicates a younger HP/LT event than previously stated. The preservation of this phengite age and constant Si-content profile indicate a short-lived HP/LT event followed by a very rapid exhumation. At 35-20 Ma rocks from the Ávila Terrane remained at shallower crustal levels than the ones of the Carayaca Terrane, but were thermally affected by tectonism and the infiltration of relatively cold and 40Ar-free fluids causing widespread chloritization of trioctahedral micas.

Evidence for shock heating and constraints on Martian surface temperatures revealed by 40Ar/ 39Ar thermochronometry of Martian meteorites

NASA Astrophysics Data System (ADS)

Cassata, William S.; Shuster, David L.; Renne, Paul R.; Weiss, Benjamin P.

2010-12-01

The thermal histories of Martian meteorite are important for the interpretation of petrologic, geochemical, geochronological, and paleomagnetic constraints that they provide on the evolution of Mars. In this paper, we quantify 40Ar/ 39Ar ages and Ar diffusion kinetics of Martian meteorites Allan Hills (ALH) 84001, Nakhla, and Miller Range (MIL) 03346. We constrain the thermal history of each meteorite and discuss the resulting implications for their petrology, paleomagnetism, and geochronology. Maskelynite in ALH 84001 yields a 40Ar/ 39Ar isochron age of 4163 ± 35 Ma, which is indistinguishable from recent Pb-Pb ( Bouvier et al., 2009a) and Lu-Hf ages ( Lapen et al., 2010). The high precision of this result arises from clear resolution of a reproducible trapped 40Ar/ 36Ar component in maskelynite in ALH 84001 ( 40Ar/ 36Ar = 632 ± 90). The maskelynite 40Ar/ 39Ar age predates the Late Heavy Bombardment and likely represents the time at which the original natural remanent magnetization (NRM) component observed in ALH 84001 was acquired. Nakhla and MIL 03346 yield 40Ar/ 39Ar isochron ages of 1332 ± 24 and 1339 ± 8 Ma, respectively, which we interpret to date crystallization. Multi-phase, multi-domain diffusion models constrained by the observed Ar diffusion kinetics and 40Ar/ 39Ar age spectra suggest that localized regions within both ALH 84001 and Nakhla were intensely heated for brief durations during shock events at 1158 ± 110 and 913 ± 9 Ma, respectively. These ages may date the marginal melting of pyroxene in each rock, mobilization of carbonates and maskelynite in ALH 84001, and NRM overprints observed in ALH 84001. The inferred peak temperatures of the shock heating events (>1400 °C) are sufficient to mobilize Ar, Sr, and Pb in constituent minerals, which may explain some of the dispersion observed in 40Ar/ 39Ar, Rb-Sr, and U-Th-Pb data toward ages younger than ˜4.1 Ga. The data also place conservative upper bounds on the long-duration residence temperatures of the ALH 84001 and Nakhla protolith to be 22-∞+8 °C and 81-∞+9 °C over the last ˜4.16 Ga and ˜1.35 Ga, respectively. MIL 03346 has apparently not experienced significant shock-heating since it crystallized, consistent with the fact that various chronometers yield concordant ages.

Cogenetic late Pleistocene rhyolite and cumulate diorites from Augustine Volcano revealed by SIMS 238U-230Th dating of zircon, and implications for silicic magma generation by extraction from mush

USGS Publications Warehouse

Coombs, Michelle L.; Vazquez, Jorge A.

2014-01-01

Augustine Volcano, a frequently active andesitic island stratocone, erupted a late Pleistocene rhyolite pumice fall that is temporally linked through zircon geochronology to cumulate dioritic blocks brought to the surface in Augustine's 2006 eruption. Zircon from the rhyolite yield a 238U-230Th age of ∼25 ka for their unpolished rims, and their interiors yield a bimodal age populations at ∼26 ka and a minority at ∼41 ka. Zircon from dioritic blocks, ripped from Augustine's shallow magmatic plumbing system and ejected during the 2006 eruption, have interiors defining a ∼26 ka age population that is indistinguishable from that for the rhyolite; unpolished rims on the dioritic zircon are dominantly younger (≤12 ka) indicating subsequent crystallization. Zircon from rhyolite and diorite overlap in U, Hf, Ti, and REE concentrations although diorites also contain a second population of high-U, high temperature grains. Andesites that brought dioritic blocks to the surface in 2006 contain zircon with young (≤9 ka) rims and a scattering of older ages, but few zircon that crystallized during the 26 ka interval. Both the Pleistocene-age rhyolite and the 2006 dioritic inclusions plot along a whole-rock compositional trend distinct from mid-Holocene–present andesites and dacites, and the diorites, rhyolite, and two early Holocene dacites define linear unmixing trends often oblique to the main andesite array and consistent with melt (rhyolite) extraction from a mush (dacites), leaving behind a cumulate amphibole-bearing residue (diorites). Rare zircon antecrysts up to ∼300 ka from all rock types indicate that a Quaternary center has been present longer than preserved surficial deposits.

Ore genesis and geodynamic setting of the Lianhuashan porphyry tungsten deposit, eastern Guangdong Province, SE China: constraints from muscovite 40Ar-39Ar and zircon U-Pb dating and Hf isotopes

NASA Astrophysics Data System (ADS)

Liu, Peng; Mao, Jingwen; Pirajno, Franco; Jia, Lihui; Zhang, Feng; Li, Yang

2017-12-01

The Lianhuashan deposit has long been regarded as a typical tungsten porphyry deposit, located in the eastern Guangdong Province, in the Southeastern Coastal Metallogenic Belt (SCMB). LA-MC-ICP-MS zircon U-Pb dating of the quartz porphyry yielded a weighted mean 206Pb/238U age of 137.3 ± 2.0 Ma, which is interpreted as the emplacement age of the quartz porphyry. Hydrothermal muscovite yielded a plateau 40Ar/39Ar age of 133.2 ± 0.9 Ma, which is consistent with the zircon U-Pb age, suggesting that the tungsten mineralization is genetically related to the quartz porphyry. Combined with previous studies, we suggest that there is a 145-135 Ma episode linking the granitic magmas with W-Sn ore systems in the SCMB. Zircon ɛHf (t) values of the quartz porphyry are in range of - 3.8 to 0.9, and the two-stage Hf model ages (TDM2) are 1.1-1.4 Ga, which is younger than the basement rocks in the Cathaysia Block (1.8-2.2 Ga), signifying that the quartz porphyry was predominantly derived from melting of Mesoproterozoic crust containing variable amounts of mantle components. In combination with the newly recognized coeval alkaline/bimodal magmatism and A-type granites in eastern Guangdong, we suggest that the 145-135 Ma W-Sn metallogenic event of the SCMB is related to a geodynamic setting of large-scale lithospheric extension and thinning, which can be ascribed to melting of the crust caused by mantle upwelling, triggered by the oblique subduction of the Izanagi plate.

Constraints on the differentiation of the Earth from the coupled Sm-146,147-Nd-142,143 systematics

NASA Technical Reports Server (NTRS)

Jacobsen, S. B.; Harper, C. L., Jr.

1993-01-01

The coupled Sm-Nd systematics are a powerful (albeit analytically challenging) tool for investigating the geodynamic history of the Earth. We have previously reported evidence for a 33 ppm difference of an Isua sample relative to our terrestrial standard. Interpretation yields a formation age range for the depleted mantle (DM) source reservoir of 4.45-4.55 Ga. This is consistent with an epoch of LREE-enriched melt extraction from the mantle (proto-crust formation), soon after magma ocean freeze-up following the putative Moon forming giant impact.

K-Ar dating and delta O-18-delta D characterization of nanometric illite from Ordovician K-bentonites of the Appalachians: illitization and the Acadian-Alleghenian tectonic activity

USGS Publications Warehouse

Clauer, Norbert; Fallick, Anthony E.; Eberl, Dennis D.; Honty, Miroslav; Huff, Warren D.; Auberti, Amelie

2013-01-01

Nanometric (2 diagram that illitization occurred in all fractions by simultaneous nucleation and crystal growth, except for one sample. In that sample, a period of growth without nucleation was detected on top of the nucleation and growth episode. The K-Ar ages organize into two isochrons, the first at 319.9 ± 2.0 Ma with an initial 40Ar/36Ar ratio of 271 ± 66 Ma, and the second at 284.9 ± 1.2 Ma with an initial 40Ar/36Ar ratio of 310 ± 44. One data point above the older isochron and three between the two isochrons suggest a detrital contamination for the former separate and a possible further generation of nanoparticles for the three others. The samples with the older crystallization age consist of illite and illite-rich mixed-layers, and those with the younger age contain smectite-rich mixed-layers without illite, or illite-enriched illite-smectite mixed-layers. The K-Ar ages fit the age trends published previously for similar K-bentonites with regional age patterns between 240 and 270 Ma in the southwestern region, between 270 and 300 Ma in the central zone and the southern Appalachians, and between 315 and 370 Ma in the northernmost. Each of the two generations of illite crystals yields very consistent δ18O (V-SMOW) values at 17 ± 1‰ for the older and at 21 ± 1‰ for the younger. If crystallization temperatures of the nanometric illite were between 100 and 200 °C, as suggested by microthermometric determinations, the hydrothermal fluids had δ18O values of 4 ± 1‰ in the Dalton district and of 8 ± 1‰ in the Lafayette, Trenton, and Dirtseller districts at 100 °C, and of 11 ± 1 and 15 ± 1‰ in the same locations at 200 °C, probably because the water-rock isotope exchanges at elevated temperature occurred in rock-dominated systems. The δ18O of the fluids remained unchanged during local crystal growth, but varied depending on the geographic location of the samples and timing of illitization. The δD (V-SMOW) values of the different size fractions do not provide consistent information; they range from −70 to −45‰ for most nanometric and micrometric fractions (V-SMOW), but with no apparent coherent pattern. Nanometric illite-rich crystals from K-bentonite that underwent tectono-thermal alteration yield constant ages, constant clay mineralogy, constant crystallite size distributions for all of the nucleating and growing illite-type crystals of each sample, as well as constant δ18O values implying constant fluid chemistry, all pointing to geologically sudden crystallization.

Calibration of the Permo-Triassic Magnetostratigraphic Time Scale: Constraints from the Dewey Lake Formation, West Texas

NASA Astrophysics Data System (ADS)

Chang, S.; Knight, K. B.; Renne, P. R.

2005-12-01

Magnetostratigraphy is potentially a powerful tool for deciphering the high resolution chronostratigraphy of events across the Permo-Triassic boundary, but few well-dated polarity reversals exist to serve as calibration. Red beds of the Dewey Lake Formation (DLF) of West Texas span three reversed polarity intervals (Steiner, 2001) in a section of the DLF at Caprock Canyons State Park, where two tuffs occur. Sanidine separated from these tuffs was analyzed by 40Ar/39Ar methods. Single crystal laser fusion 40Ar/39Ar analyses of 40 grains from the upper tuff yield a weighted mean age of 249.9 ± 2.4 Ma (2σ errors here and throughout). The clustering of single crystal data provides some assurance against xenocrystic contamination. Two age spectra from multigrain sanidine separates from the lower tuff yielded integrated ages of 248.9 ± 2.8 Ma and 249.7 ± 2.8 Ma and consistent plateau ages of 249.2 ± 2.4 Ma and 249.6 ± 2.4 Ma. Two age spectra from multigrain upper tuff sanidines lack strict plateaus but with overall flat age spectra, with integrated ages of 249.7 ± 2.8 Ma and 250.3 ± 2.8 Ma and plateau-like segments (>70% of 39Ar released) with ages of 249.9 ± 2.6 Ma and 249.9 ± 2.6 Ma, respectively. These results, compared with 40Ar/39Ar data (using the same FCs = 28.02 Ma standard calibration) from the GSSP section at Meishan, China, suggest that the Permo-Triassic boundary (249.8 Ma; recalculated from Renne et al., 1995) definitely occurs within the lower Dewey Lake Formation. The two tuffs, which bracket a normal to reverse geomagnetic polarity transition polarity (Steiner, 2001), have indistinguishable ages. The age of this Permo-Triassic polarity transition is thus best represented by the weighed average of their ages, ca. 249.7 Ma (based on accepted calibrations of the 40Ar/39Ar system). Further such constraints will facilitate high-resolution comparison of terrestrial and marine records across this critical time interval.

The Effect of Artificial Aging on the Tensile Properties of Alclad 24S-T and 24S-T Aluminum Alloy

NASA Technical Reports Server (NTRS)

Kotanchik, Joseph N.; Woods, Walter; Zender, George W.

1943-01-01

An experimental study was made to determine the effect of artificial aging on the tensile properties of alclad 24S-T and 24S-T aluminum-alloy sheet material. The results of the tests show that certain combinations of aging time and temperature cause a marked increase in the yield strength and a small increase in the ultimate strength; these increases are accompanied by a very large decrease in elongation. A curve is presented that shows the maximum yield strengths that can be obtained by aging this material at various combinations of time and temperature. The higher values of yield stress are obtained in material aged at relatively longer times and lower temperatures.

Modelling the growth of the brown frog (Rana dybowskii)

PubMed Central

Du, Xiao-peng; Hu, Zong-fu; Cui, Li-yong

2018-01-01

Well-controlled development leads to uniform body size and a better growth rate; therefore, the ability to determine the growth rate of frogs and their period of sexual maturity is essential for producing healthy, high-quality descendant frogs. To establish a working model that can best predict the growth performance of frogs, the present study examined the growth of one-year-old and two-year-old brown frogs (Rana dybowskii) from metamorphosis to hibernation (18 weeks) and out-hibernation to hibernation (20 weeks) under the same environmental conditions. Brown frog growth was studied and mathematically modelled using various nonlinear, linear, and polynomial functions. The model input values were statistically evaluated using parameters such as the Akaike’s information criterion. The body weight/size ratio (Kwl) and Fulton’s condition factor (K) were used to compare the weight and size of groups of frogs during the growth period. The results showed that the third- and fourth-order polynomial models provided the most consistent predictions of body weight for age 1 and age 2 brown frogs, respectively. Both the Gompertz and third-order polynomial models yielded similarly adequate results for the body size of age 1 brown frogs, while the Janoschek model produced a similarly adequate result for the body size of age 2 brown frogs. The Brody and Janoschek models yielded the highest and lowest estimates of asymptotic weight, respectively, for the body weights of all frogs. The Kwl value of all frogs increased from 0.40 to 3.18. The K value of age 1 frogs decreased from 23.81 to 9.45 in the first four weeks. The K value of age 2 frogs remained close to 10. Graphically, a sigmoidal trend was observed for body weight and body size with increasing age. The results of this study will be useful not only for amphibian research but also for frog farming management strategies and decisions.

High precision thorium-230 ages of corals and the timing of sea level fluctuations in the late Quaternary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edwards, R.L.

1988-01-01

Mass spectrometric techniques for the measurement of {sup 230}Th and {sup 234}U have been developed. These techniques have made it possible to reduce the analytical errors in {sup 230}Th dating of corals using very small samples (10{sup 7} to 10{sup 10} atoms). The time range over which useful data on corals can now be obtained ranges from 15 to 500,000 years. For young corals, this approach may be preferable to {sup 14}C dating. The precision with which the age of a coral can not be determined makes it possible to determine the timing of sea level fluctuations in the latemore » Quaternary. Analyses of a number of corals that grew during the last interglacial period yield ages of 122 to 130 ky. The ages coincide with or slightly postdate the summer solar insolation high at 65{degree}N latitude, which occurred 128 ky ago. This supports the idea that changes in Pleistocene climate can be the result of orbital forcing. Coral ages may allow us to resolve the ages of individual coseismic uplift events and thereby date prehistoric earthquakes. This possibility has been examined at two localities, northwest Santo Island and north Malekula Island, Vanuatu. The {sup 230}Th growth dates of the surfaces of adjacent emerged coral heads, collected from the same elevation on northwest Santo Island, were, within analytical error, identical (A.D. 1866 {plus minus} 4 and A.D. 1864 {plus minus} 4). This indicates that the corals died at the same time and is consistent with the idea that they were killed by coseismic uplift. Similar adjacent coral heads on north Malekula Island yielded {sup 230}Th growth dates of A.D. 1729 {plus minus} 3 and A.D. 1718 {plus minus} 5. The ages are similar but analytically distinguishable. The difference may be due to erosion of the outer, younger, portion of the latter coral head.« less

The single grain fusion dating approach: Determining the factors that control white mica 40Ar/39Ar age formation during HP metamorphism of the Cycladic Blueschist Unit, Greece

NASA Astrophysics Data System (ADS)

Uunk, Bertram; Wijbrans, Jan; Brouwer, Fraukje

2017-04-01

White mica 40Ar/39Ar dating is a proven powerful tool for constraining the timing and rate of metamorphism, deformation and exhumation. However, for high-pressure metamorphic rocks dating often results in wide age ranges, which are not in agreement with constraints from other isotopic systems, indicating that geological and chemical processes complicate straightforward 40Ar/39Ar dating. Despite hosting one of the largest geochronological datasets in the world, the Cycladic Blueschist Unit in Greece is presently one of the focal areas in the discussion on the interpretation of metamorphic 40Ar/39Ar ages. Previous phengite multi grain step heating experiments commonly yielded undulating age spectra ranging between 20 - 60 Ma. While some studies attempt to assign geological significance to these ages, others argue the ages are geologically meaningless and the result of the interplay between partial diffusive resetting and continued crystallization. By taking an alternative approach of multiple single grain fusion experiments, this study investigates age heterogeneity between samples of contrasting metamorphic facies, rheology and strain from the Cycladic islands of Syros and Sifnos. Comparing the size and shape of single grain fusion age distributions at the grain, rock, outcrop and island scale allows determination of the scale at which different age-forming processes operate. Resulting ages show a previously unreported consistent variation between different outcrops, moving from the eclogite-blueschist facies (55-45 Ma) to greenschist overprinting (40-30 Ma). This indicates that outcrop scale homogeneous resetting is the dominant processes for age formation in the CBU. Single grain age variation at the sample and outcrop scale is only limited to 10 Ma, indicating a smaller but observable role for local age perturbing processes of incomplete resetting, continued (re)crystallization or infiltration of excess argon. Some of the partially overprinted samples show homogeneous single grain age populations, indicating at least a partial role for efficient resetting by thermally activated diffusion at the outcrop scale. Traditional multi grain step heating experiments on the same samples yield flat plateaus for various single grain age distributions, indicating that age heterogeneities resolved by single grain fusion dating are mixed to a meaningless average in step heating experiments. In contrast, our approach leads to a better understanding of the processes responsible for age formation during high pressure metamorphism.

Evaluation of Thompson-type trend and monthly weather data models for corn yields in Iowa, Illinois, and Indiana

NASA Technical Reports Server (NTRS)

French, V. (Principal Investigator)

1982-01-01

An evaluation was made of Thompson-Type models which use trend terms (as a surrogate for technology), meteorological variables based on monthly average temperature, and total precipitation to forecast and estimate corn yields in Iowa, Illinois, and Indiana. Pooled and unpooled Thompson-type models were compared. Neither was found to be consistently superior to the other. Yield reliability indicators show that the models are of limited use for large area yield estimation. The models are objective and consistent with scientific knowledge. Timely yield forecasts and estimates can be made during the growing season by using normals or long range weather forecasts. The models are not costly to operate and are easy to use and understand. The model standard errors of prediction do not provide a useful current measure of modeled yield reliability.

Age and Zebu-Holstein additive and heterotic effects on lactation performance and reproduction in Brazil.

PubMed

Martinez, M L; Lee, A J; Lin, C Y

1988-03-01

Data of 6482 lactations from 14 crossbred (Holstein x Zebu) herds in Brazil were used to study breed additive and heterosis effects for first, second, third, and first to fifth lactation milk yields, age at first calving, calving interval, and milk yield divided by calving interval, as well as the effect of age at calving on milk yield. Holstein additive expressed as deviation from Zebu and heterosis effects were highly significant for all traits. For each percentage of Holstein gene contribution an increase of 10.02, 12.02, 12.51, and 12.15 kg of milk were expected for first, second, third, and first to fifth lactation yields, respectively. Corresponding heterosis effects on those traits were 3.80, 3.39, 4.02, and 3.90 kg of milk for each percentage of heterozygosity. Replacement of pure Zebu genes by Holstein genes reduced age at first calving by 6 mo and shortened calving interval by 37 d. Holstein x Zebu heterotic effect decreased age at first calving by 2 mo and calving interval by 39 d. Holstein additive and heterosis effects for milk yield divided by calving interval were 3.4 and 1.3 kg of milk/d, respectively. Fitting breed additive and heterozygosity effects accounted for 99% of the genetic effects except for first to fifth lactation milk yield.

Recognizing Age-Separated Face Images: Humans and Machines

PubMed Central

Yadav, Daksha; Singh, Richa; Vatsa, Mayank; Noore, Afzel

2014-01-01

Humans utilize facial appearance, gender, expression, aging pattern, and other ancillary information to recognize individuals. It is interesting to observe how humans perceive facial age. Analyzing these properties can help in understanding the phenomenon of facial aging and incorporating the findings can help in designing effective algorithms. Such a study has two components - facial age estimation and age-separated face recognition. Age estimation involves predicting the age of an individual given his/her facial image. On the other hand, age-separated face recognition consists of recognizing an individual given his/her age-separated images. In this research, we investigate which facial cues are utilized by humans for estimating the age of people belonging to various age groups along with analyzing the effect of one's gender, age, and ethnicity on age estimation skills. We also analyze how various facial regions such as binocular and mouth regions influence age estimation and recognition capabilities. Finally, we propose an age-invariant face recognition algorithm that incorporates the knowledge learned from these observations. Key observations of our research are: (1) the age group of newborns and toddlers is easiest to estimate, (2) gender and ethnicity do not affect the judgment of age group estimation, (3) face as a global feature, is essential to achieve good performance in age-separated face recognition, and (4) the proposed algorithm yields improved recognition performance compared to existing algorithms and also outperforms a commercial system in the young image as probe scenario. PMID:25474200

Recognizing age-separated face images: humans and machines.

PubMed

Yadav, Daksha; Singh, Richa; Vatsa, Mayank; Noore, Afzel

2014-01-01

Humans utilize facial appearance, gender, expression, aging pattern, and other ancillary information to recognize individuals. It is interesting to observe how humans perceive facial age. Analyzing these properties can help in understanding the phenomenon of facial aging and incorporating the findings can help in designing effective algorithms. Such a study has two components--facial age estimation and age-separated face recognition. Age estimation involves predicting the age of an individual given his/her facial image. On the other hand, age-separated face recognition consists of recognizing an individual given his/her age-separated images. In this research, we investigate which facial cues are utilized by humans for estimating the age of people belonging to various age groups along with analyzing the effect of one's gender, age, and ethnicity on age estimation skills. We also analyze how various facial regions such as binocular and mouth regions influence age estimation and recognition capabilities. Finally, we propose an age-invariant face recognition algorithm that incorporates the knowledge learned from these observations. Key observations of our research are: (1) the age group of newborns and toddlers is easiest to estimate, (2) gender and ethnicity do not affect the judgment of age group estimation, (3) face as a global feature, is essential to achieve good performance in age-separated face recognition, and (4) the proposed algorithm yields improved recognition performance compared to existing algorithms and also outperforms a commercial system in the young image as probe scenario.

Large mid-Holocene and late Pleistocene earthquakes on the Oquirrh fault zone, Utah

USGS Publications Warehouse

Olig, S.S.; Lund, W.R.; Black, B.D.

1994-01-01

The Oquirrh fault zone is a range-front normal fault that bounds the east side of Tooele Valley and it has long been recognized as a potential source for large earthquakes that pose a significant hazard to population centers along the Wasatch Front in central Utah. Scarps of the Oquirrh fault zone offset the Provo shoreline of Lake Bonneville and previous studies of scarp morphology suggested that the most recent surface-faulting earthquake occurred between 9000 and 13,500 years ago. Based on a potential rupture length of 12 to 21 km from previous mapping, moment magnitude (Mw) estimates for this event range from 6.3 to 6.6 In contrast, our results from detailed mapping and trench excavations at two sites indicate that the most-recent event actually occurred between 4300 and 6900 yr B.P. (4800 and 7900 cal B.P.) and net vertical displacements were 2.2 to 2.7 m, much larger than expected considering estimated rupture lengths for this event. Empirical relations between magnitude and displacement yield Mw 7.0 to 7.2. A few, short discontinuous fault scarps as far south as Stockton, Utah have been identified in a recent mapping investigation and our results suggest that they may be part of the Oquirrh fault zone, increasing the total fault length to 32 km. These results emphasize the importance of integrating stratigraphic and geomorphic information in fault investigations for earthquake hazard evaluations. At both the Big Canyon and Pole Canyon sites, trenches exposed faulted Lake Bonneville sediments and thick wedges of fault-scarp derived colluvium associated with the most-recent event. Bulk sediment samples from a faulted debris-flow deposit at the Big Canyon site yield radiocarbon ages of 7650 ?? 90 yr B.P. and 6840 ?? 100 yr B.P. (all lab errors are ??1??). A bulk sediment sample from unfaulted fluvial deposits that bury the fault scarp yield a radiocarbon age estimate of 4340 ?? 60 yr B.P. Stratigraphic evidence for a pre-Bonneville lake cycle penultimate earthquake was exposed at the Pole Canyon site, and although displacement is not well constrained, the penultimate event colluvial wedge is comparable in size to the most-recent event wedges. Charcoal from a marsh deposit, which overlies the penultimate event colluvium and was deposited during the Bonneville lake cycle transgression, yields an AMS radiocarbon age of 20,370 ?? 120 yr B.P. Multiple charcoal fragments from fluvial deposits faulted during the penultimate event yield an AMS radiocarbon age of 26,200 ?? 200 yr B.P. Indirect stratigraphic evidence for an antepenultimate event was also exposed at Pole Canyon. Charcoal from fluvial sediments overlying the eroded free-face for this event yields an AMS age of 33,950 ?? 1160 yr B.P., providing a minimum limiting age on the antepenultimate event. Ages for the past two events on the Oquirrh fault zone yield a recurrence interval of 13,300 to 22,100 radiocarbon years and estimated slip rates of 0.1 to 0.2 mm/yr. Temporal clustering of earthquakes on the nearby Wasatch fault zone in the late Holocene does not appear to have influenced activity on the Oquirrh fault zone. However, consistent with findings on the Wasatch fault zone and with some other Quaternary faults within the Bonneville basin, we found evidence for higher rates of activity during interpluvial periods than during the Bonneville lake cycle. If a causal relation between rates of strain release along faults and changes in loads imposed by the lake does exist, it may have implications for fault dips and mechanics. However, our data are only complete for one deep-lake cycle (the past 32,000 radiocarbon years), and whether this pattern persisted during the previous Cutler Dam and Little Valley deep-lake cycles is unknown. ?? 1994.

Single-Grain (U-Th)/He Ages of Phosphates from St. Severin Chondrite

NASA Astrophysics Data System (ADS)

Min, K. K.; Reiners, P. W.; Shuster, D. L.

2010-12-01

Thermal evolution of chondrites provides valuable information on the heat budget, internal structure and dimensions of their parent bodies once existed before disruption. St. Severin LL6 ordinary chondrite is known to have experienced relatively slow cooling compared to H chondrites. The timings of primary cooling and subsequent thermal metamorphism were constrained by U/Pb (4.55 Ga), Sm/Nd (4.55 Ga), Rb/Sr (4.51 Ga) and K/Ar (4.4 Ga) systems. However, cooling history after the thermal metamorphism in a low temperature range (<200 °C) is poorly understood. In order to constrain the low-T thermal history of this meteorite, we performed (1) single-grain (U-Th)/He dating for five chlorapatite and fourteen merrillite aggregates from St. Severin, (2) examination of textural and chemical features of the phosphate aggregates using a scanning electron microscope (SEM), and (3) proton-irradiation followed by 4He and 3He diffusion experiments for single grains of chlorapatite and merrillite from Guarena meteorite, for general characterization of He diffusivity in these major U-Th reservoirs in meteorites. The α-recoil-uncorrected ages from St. Severin are distributed in a wide range of 333 ± 6 Ma and 4620 ± 1307 Ma. The probability density plot of these data shows a typical younging-skewed age distribution with a prominent peak at ~ 4.3 Ga. The weighted mean of the nine oldest samples is 4.284 ± 0.130 Ga, which is consistent with the peak of the probability plot. The linear dimensions of the phosphates are generally in the range of ~50 µm to 200 µm. The α recoil correction factor (FT) based on the morphology of the phosphate yields improbably old ages (>4.6 Ga), suggesting that within the sample aggregates, significant amounts of the α particles ejected from phosphates were implanted into the adjacent phases and therefore that this correction may not be appropriate in this case. The minimum FT value of 0.95 is calculated based on the peak (U-Th)/He age and 40Ar/39Ar data which provide the upper limit of the α-recoil-corrected (U-Th)/He ages. From these data, we conclude that the St. Severin cooled through the closure temperatures of chlorapatite and merrillite during ~4.3 - 4.4 Ga. The radiogenic 4He and proton-induced 3He diffusion experiments yield two well-defined linear trends in Arrhenius plot for chlorapatite (r = 43 µm) and merrillite (r = 59 µm) grains. The linear regression of 3He data for chlorapatite yields Ea = 128.1 ± 2.4 kJ/mol, and ln(Do/a2) = 11.6 ± 0.5 ln(s-1) which are generally consistent with the terrestrial Durango apatite and meteoritic Acapulco apatite. Linear regression to the merrillite data corresponds to Ea = 135.1 ± 2.5 kJ/mol, and ln(Do/a2) = 5.73 ± 0.37 ln(s-1). The new data indicate that diffusive retentivity of He within merrillite is significantly higher than that of chlorapatite, which has implications for quantitative interpretation of He ages measured in meteoritic phosphates.

Assessing the Potential Oleoresin Yields of Slash Pine Progenies at Juvenile Ages

Treesearch

A.E. Squillace; Charles R. Gansel

1968-01-01

The potential oleoresin yields of slash pine progenies can be assessed at juvenile ages, 7 to 8 years earlier than with previous methods. Seeds are sown in peat pots, outplanted shortly after germination at a spacing of 14 by 3 feet, and given intensive cultural treatment. At 26 years from seed, when the trees average about 9 feet tall, their potential yields are...

OAKSIM: An individual-tree growth and yield simulator for managed, even-aged, upland oak stands

Treesearch

Donald E. Hilt; Donald E. Hilt

1985-01-01

OAKSIM is an individual-tree growth and yield simulator for managed, even-aged, upland oak stands. Growth and yield projections for various thinning alternatives can be made with OAKSIM for a period of up to 50 years. Simulator components include an individual-tree diameter growth model, a mortality model, height prediction equations, bark ratio equations, a taper-...

Dating the Gaofan and Hutuo Groups - Targets to investigate the Paleoproterozoic Great Oxidation Event in North China

NASA Astrophysics Data System (ADS)

Peng, Peng; Feng, Lianjun; Sun, Fengbo; Yang, Shuyan; Su, Xiangdong; Zhang, Zhiyue; Wang, Chong

2017-05-01

There are several sedimentary units in North China that are proposed to be associated with the Paleoproterozoic Great Oxidation Event (GOE) and/or subsequent events; however, few of them have been precisely dated. In this study, deposition age of the greenschist facies Gaofan and Hutuo Groups is determined. Zircon grains liberated from a tuff layer (metamorphosed to sericite-quartz schist) in the upper part of the Mohe Formation (the second of the three formations of the Gaofan Group) yield a weighted average 207Pb/206Pb age of 2186 ± 8 Ma (n = 7, MSWD = 1.3), representing time of deposition. This age and the detrital zircon U-Pb ages of the basal feldspar quartzite (meta-siltstone), as well as the initial deposition age of the unconformably overlying Hutuo Group, confine the deposition age of the Gaofan Group to 2350-2150 Ma. This result negates the Gaofan Group as one subgroup of the 2560-2510 Ma Wutai greenstone belt. Zircons from the Banlaoyao mafic sill (meta-diabase) that intruded the Dongye Subgroup of the Hutuo Group yield an upper intercept U-Pb age of 2057 ± 25 Ma (n = 14, MSWD = 1.3), representing time of crystallization. Considering the age of the basalt in the first formation of the Doucun Subgroup and the tuff in the first formation of the Dongye Subgroup, the deposition age of the Doucun and Dongye Subgroups of the Hutuo Group is confined to 2150-2090 Ma and 2090-2060 Ma, respectively. These age brackets, as well as the available carbon and nitrogen isotope data indicate that the Zhangxianbu Formation of the Gaofan Group possibly recorded the GOE; whereas the Mohe-Yaokouqian Formations of the Gaofan Group and the Doucun-Dongye Subgroups of the Hutuo Group recorded the subsequent Lomagundi-Jatuli Event (LJE). However, the Lomagundi-Jatuli carbon excursions are hardly distinguishable from the Gaofan Group and the Doucun Subgroup (Hutuo Group) as both units consist of little inorganic carbon but terrestrial clastic turbidites.

Spatial and Temporal Patterns of Suspended Sediment Yields in Nested Urban Catchments

NASA Astrophysics Data System (ADS)

Kemper, J. T.; Miller, A. J.; Welty, C.

2017-12-01

In a highly regulated area such as the Chesapeake Bay watershed, suspended sediment is a matter of primary concern. Near real-time turbidity and discharge data have been collected continuously for more than four years at five stream gages representing three nested watershed scales (1-2 sq km, 5-6 sq km, 14 sq km) in the highly impervious Dead Run watershed, located in Baltimore County, MD. Using turbidity-concentration relationships based on sample analyses at the gage site, sediment yields for each station can be quantified for a variety of temporal scales. Sediment yields have been calculated for 60+ different storms across four years. Yields show significant spatial variation, both at equivalent sub-watershed scales and from headwaters to mouth. Yields are higher at the headwater station with older development and virtually no stormwater management (DR5) than at the station with more recent development and more extensive stormwater management (DR2). However, this pattern is reversed for the stations at the next larger scale: yields are lower at DR4, downstream of DR5, than at DR3, downstream of DR2. This suggests spatial variation in the dominant sediment sources within each subwatershed. Additionally, C-Q hysteresis curves display consistent counterclockwise behavior at the DR4 station, in contrast to the consistent clockwise behavior displayed at the DR3 station. This further suggests variation in dominant sediment sources (perhaps distal vs local, respectively). We observe consistent seasonal trends in the relative magnitudes of sediment yield for different subwatersheds (e.g. DR3>DR4 in summer, DR5>DR2 in spring). We also observe significant year-to-year variation in sediment yield at the headwater and intermediate scales, whereas yields at the 14 sq km scale are largely similar across the monitored years. This observation would be consistent with the possibility that internal storage and remobilization tend to modulate downstream yields even with spatial and temporal variation in upstream sources. The fine-scale design of this study represents a unique opportunity to compare and contrast sediment yields across a variety of spatial and temporal scales, and provide insight into sediment transport dynamics within an urbanized watershed.

Observations of Static Strain-Aging in Polycrystalline NiAl

NASA Technical Reports Server (NTRS)

Weaver, M. L.; Noebe, R. D.; Lewandowski, J. J.; Oliver, B. F.; Kaufman, M. J.

1996-01-01

Static strain-aging has been investigated in eight polycrystalline NiAl alloys. After annealing at 1100 K for 7200 s followed by furnace cooling, high-purity, nitrogen-doped, and titanium-doped alloys exhibited continuous yielding, while conventional-purity and carbon-doped alloys exhibited distinct upper yield points and Luders strains. Either water quenching from 1100 K or prestraining via hydrostatic pressurization suppressed the yield points in the latter alloys, but they could be reintroduced by further annealing treatments. Yield points could be reintroduced more rapidly if the specimens were prestrained uniaxially rather than hydrostatically, owing to the arrangement of dislocations into cell structures during uniaxial deformation. Chemical analysis suggests that the species responsible for strain-aging is interstitial carbon.

Reaction process of {alpha} {yields} {gamma} massive transformation in Ti-rich TiAl alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumagai, T.; Abe, E.; Nakamura, M.

1995-08-01

Reaction sequence of the massive transformation from the high-temperature {alpha}-Ti phase to the {gamma}-TiAl phase ({gamma}{sub m}) in a Ti-48at.% Al alloy has been examined in terms of optical and transmission electron microscopes. Both transformed and untransformed regions were macroscopically observed in the sample quenched from the high-temperature {alpha} phase field, when the sample was held there for a extended period of time prior to quenching. The transformed region consists of randomly oriented fine {gamma} single phase grains, in which many thermal anti-phase domains (TAPDs), together with a number of stacking faults were observed. In contrast, the untransformed region comprisesmore » extremely fine lamellae of the {gamma} and {alpha}{sub 2}-Ti{sub 3}Al phases, and the {gamma} plates were found to run through the TAPDs caused by {alpha} {yields} {alpha}{sub 2} ordering. Subsequent aging at 1,273 K causes the microstructure change in the untransformed region from {alpha}{sub 2}/{gamma} lamellae to {gamma}/{gamma} lamellae spontaneously and expands the {gamma}{sub m} region. These observations suggest that the {alpha} {yields} {gamma}{sub m} transformation proceeds through formation of fine {gamma} plates.« less

An evaluation of aquifer and well characteristics of municipal well fields in Los Alamos and Guaje Canyons, near Los Alamos, New Mexico

USGS Publications Warehouse

Cushman, Robert L.

1965-01-01

The Jenkins-Whitesburg area includes approximately 250 square miles In Letcher and Pike Counties in the southeastern part of the Eastern Coal Field. In this area ground water is the principal source of water for nearly all rural families, most public supplies, several coal mines and coal processing plants, and one bottling plant. The major aquifers in the Jenkins-Whitesburg area are the Breathitt and Lee Formations of Pennsylvanian age. Other aquifers range in age from Devonian to Quaternary but are not important in this area because they occur at great depth or yield little or no water. The Breathitt Formation occurs throughout the area except along the crest and slopes of Pine Mountain and where it is covered by unconsolidated material of Quaternary age. The Breathitt Formation consists of shale, sandstone, and lesser amounts of coal and associated underclay. The yield of wells penetrating the Breathitt Formation ranges from less than 1 to 330 gallons per minute. Well yield is controlled by the type and depth of well, character of the aquifer, and topography of the well site. Generally, deep wells drilled in valleys of perennial streams offer the best potential for high yields. Although enough water for a minimum domestic supply (more than 100 gallons per day) may be obtained from shale, all high-yielding wells probably obtain water from vertical joints and from bedding planes which are best developed in sandstone. About 13 percent of the wells inventoried in the Breathitt Formation failed to supply enough water for a minimum domestic supply. Most of these are shallow dug wells or drilled wells on hillsides or hilltops. Abandoned coal dunes are utilized as large infiltration galleries and furnish part of the water for several public supplies. The chemical quality of water from the Breathitt Formation varies considerably from place to place, but the water generally is acceptable for most domestic and industrial uses. Most water is a calcium magnesium bicarbonate or sodium bicarbonate type, and nearly all sampled water contained enough iron to stain cooking and laundry utensils. The water ranged from soft to very hard, and only one well in the Breathitt Formation produced salty water. The absence of salty water may be due to abundant fractures which are associated with the Pine Mountain fault and which have allowed fresh water to enter the formation. The Lee Formation underlies the Cumberland Mountain section and is exposed along the crest and southeast slope of Pine Mountain. The Lee Formation consists of massive sandstone and conglomerate with thin beds of shale and a few thin coal seams. Although the Lee Formation is tapped by only a few wells in this area, it is potentially an important aquifer. Wells penetrating the Lee Formation in the Cumberland Mountain section would probably yield water under artesian pressure. Unlike most water from the Lee Formation in other part.3 of eastern Kentucky, all water from the Lee Formation in the Jenkins-Whitesburg area is fresh. All water from the Lee Formation contained more than 0.3 parts per million of iron and ranged from soft to moderately hard.

Survey Field Methods for Expanded Biospecimen and Biomeasure Collection in NSHAP Wave 2

PubMed Central

Jaszczak, Angela; Hoffmann, Joscelyn N.; You, Hannah M.; Kern, David W.; Pagel, Kristina; McPhillips, Jane; Schumm, L. Philip; Dale, William; Huang, Elbert S.; McClintock, Martha K.

2014-01-01

Objectives. The National Social Life, Health, and Aging Project is a nationally representative, longitudinal survey of older adults. A main component is the collection of biomeasures to objectively assess physiological status relevant to psychosocial variables, aging conditions, and disease. Wave 2 added novel biomeasures, refined those collected in Wave 1, and provides a reference for the collection protocols and strategy common to the biomeasures. The effects of aging, gender, and their interaction are presented in the specific biomeasure papers included in this Special Issue. Method. A transdisciplinary working group expanded the biomeasures collected to include physiological, genetic, anthropometric, functional, neuropsychological, and sensory measures, yielding 37 more than in Wave 1. All were designed for collection in respondents’ homes by nonmedically trained field interviewers. Results. Both repeated and novel biomeasures were successful. Those in Wave 1 were refined to improve quality, and ensure consistency for longitudinal analysis. Four new biospecimens yielded 27 novel measures. During the interview, 19 biomeasures were recorded covering anthropometric, functional, neuropsychological, and sensory measures and actigraphy provided data on activity and sleep. Discussion. Improved field methods included in-home collection, temperature control, establishment of a central survey biomeasure laboratory, and shipping, all of which were crucial for successful collection by the field interviewers and accurate laboratory assay of the biomeasures (92.1% average co-operation rate and 97.3% average assay success rate). Developed for home interviews, these biomeasures are readily applicable to other surveys. PMID:25360025

Marination and Physicochemical Characteristics of Vacuum-aged Duck Breast Meat.

PubMed

Khan, Muhammad Issa; Lee, Hyun Jung; Kim, Hyun-Joo; Young, Hae In; Lee, Haelim; Jo, Cheorun

2016-11-01

We investigated marinade absorption and physicochemical characteristics of vacuum-aged duck breasts that were halved and individually vacuum-packed for chiller aging at 4°C for 14 d. One half was marinated for 0, 7, or 14 d, while the second half was used as a control. Marinade absorption, cooking loss, cooking yield, texture profile, pH, color, protein solubility, and thiobarbituric acid reactive substances (TBARS) values were evaluated, and protein sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed. Marinade absorption and pH did not vary significantly after 14 d of aging. Marination increased the pH, color (a* and b*) values, and cooking yield and reduced cooking loss. TBARS values significantly increased with aging time, but were significantly reduced by marination. Myofibril and total protein solubility increased with aging and marination, while SDS-PAGE showed protein degradation. Hence, aging and marination can be used simultaneously to improve physicochemical quality and cooking yield of vacuum-aged duck breast.

Application of Appropriate Use Criteria for Initial Transthoracic Echocardiography in an Academic Outpatient Pediatric Cardiology Program.

PubMed

Safa, Raya; Aggarwal, Sanjeev; Misra, Amrit; Kobayashi, Daisuke

2017-08-01

Transthoracic echocardiography (TTE) is a non-invasive diagnostic modality for children with suspected heart disease. The American College of Cardiology published Appropriate Use Criteria (AUC) for an initial outpatient pediatric TTE in 2014 to promote effective care and improve resource utilization. The objective was to determine the appropriateness of TTE per the published AUC in a single academic pediatric cardiology clinic as a baseline performance quality measure. The echocardiography database was used to identify initial outpatient TTE in children during January-March 2014. TTE indications (appropriate [A], may be appropriate [M], or rarely appropriate [R]) and findings (normal, incidental, or abnormal) were recorded. The effect of AUC and age groups on yield of abnormal TTE findings was analyzed. Of the 2166 screened studies, our study cohort consisted of 247 TTEs. Indications rated A, M, and R were found in 129, 27, and 90, respectively, and 1 was unclassifiable. Majority of TTE (n = 183) were normal, although incidental findings were noted in 32 and abnormal findings in 32 cases. Abnormal findings were noted in 26/129 of A, 2/27 of M, and 4/90 of R. Indications rated A were significantly associated with yield of abnormal TTE findings, adjusted by age group. Infants and adolescents were more likely to have abnormal TTE findings compared to young children. Recently published AUC were validated for initial TTE in the outpatient pediatric cardiology clinic. Appropriateness rated by AUC was highly associated with yield of abnormal TTE findings and worked best in infants and adolescent.

Age-related Differential Item Functioning for the Patient-Reported Outcomes Information System (PROMIS®) Physical Functioning Items.

PubMed

Paz, Sylvia H; Spritzer, Karen L; Morales, Leo S; Hays, Ron D

2013-03-29

To evaluate the equivalence of the PROMIS® wave 1 physical functioning item bank, by age (50 years or older versus 18-49). A total of 114 physical functioning items with 5 response choices were administered to English- (n=1504) and Spanish-language (n=640) adults. Item frequencies, means and standard deviations, item-scale correlations, and internal consistency reliability were estimated. Differential Item Functioning (DIF) by age was evaluated. Thirty of the 114 items were fagged for DIF based on an R-squared of 0.02 or above criterion. The expected total score was higher for those respondents who were 18-49 than those who were 50 or older. Those who were 50 years or older versus 18-49 years old with the same level of physical functioning responded differently to 30 of the 114 items in the PROMIS® physical functioning item bank. This study yields essential information about the equivalence of the physical functioning items in older versus younger individuals.

Dissociative Global and Local Task-Switching Costs Across Younger Adults, Middle-Aged Adults, Older Adults, and Very Mild Alzheimer Disease Individuals

PubMed Central

Huff, Mark J.; Balota, David A.; Minear, Meredith; Aschenbrenner, Andrew J.; Duchek, Janet M.

2015-01-01

A task-switching paradigm was used to examine differences in attentional control across younger adults, middle-aged adults, healthy older adults, and individuals classified in the earliest detectable stage of Alzheimer's disease (AD). A large sample of participants (570) completed a switching task in which participants were cued to classify the letter (consonant/vowel) or number (odd/even) task-set dimension of a bivalent stimulus (e.g., A 14), respectively. A Pure block consisting of single-task trials and a Switch block consisting of nonswitch and switch trials were completed. Local (switch vs. nonswitch trials) and global (nonswitch vs. pure trials) costs in mean error rates, mean response latencies, underlying reaction time distributions, along with stimulus-response congruency effects were computed. Local costs in errors were group invariant, but global costs in errors systematically increased as a function of age and AD. Response latencies yielded a strong dissociation: Local costs decreased across groups whereas global costs increased across groups. Vincentile distribution analyses revealed that the dissociation of local and global costs primarily occurred in the slowest response latencies. Stimulus-response congruency effects within the Switch block were particularly robust in accuracy in the very mild AD group. We argue that the results are consistent with the notion that the impaired groups show a reduced local cost because the task sets are not as well tuned, and hence produce minimal cost on switch trials. In contrast, global costs increase because of the additional burden on working memory of maintaining two task sets. PMID:26652720

Toward a high-resolution 40Ar/39Ar geochronology of the Tatun Volcano Group, Taiwan

NASA Astrophysics Data System (ADS)

Mesko, G. T.; Song, S.; Chang, S.; Hemming, S. R.; Turrin, B. D.

2010-12-01

The Tatun Volcano Group [TVG] consists of five volcanic subgroups of which ~30 edifices have been identified, all in close proximity to the densely populated Taipei Basin to its south (Song et al., 2000, Journal of the Geological Society of China, in Chinese). Evidence of eruptions is in the form of mostly lava flows, with pyroclastic flows, and ash deposition (Tsai et al., 2010, TAO), consistent with vulcanian and plinian eruptions that are only minimally preserved because of the region’s high weathering rate (Belousov et al., 2010, Journal of Volcanology and Geothermal Research). The TVG is made up of calc-alkaline andesite, with few interspersed basaltic lava flows that bear geochemical signatures consistent with subduction volcanism, yet due to tectonic location Teng (1996, Geology) describes it as Ryukyu back-arc basin volcanism, and still others attribute volcanism here to post-collisional collapse of the Taiwan orogen (Wang et al., 1999, Tectonophysics and 2004, Journal of Petrology). Various TVG samples were previously K-Ar dated by Juang and Chen (1989, Bulletin of Central Geological Survey, in Chinese), Tsao (1994, Bulletin of Central Geological Survey, in Chinese), and 40Ar/39Ar whole rock analyses by Lee (1996, masters thesis, National Taiwan University) to suggest volcanism from 2.8-2.5Ma and then from 1.5-.22Ma after which volcanic events ceased. In contrast, radiocarbon dates obtained from charcoal in related sediment by Chen et al. (2010, TAO) and Belousov et al. (2010, Journal of Volcanology Geothermal Research) suggest volcanic activity was present at 20ka and 6ka respectively. The andesite samples are microcrystalline; therefore hand picked aliquots of groundmass from the hand magnetic fraction were subjected to several iterations of sonic rinse in glycine-based soap, then 4N HNO3, then quartz-distilled water in a preparation modified from Nicolaysen et al. (2000, EPSL). Samples were co-irradiated at the USGS facility in Denver using Alder Creek sanidine monitor standard, with an assumed age of 1.193±.001Ma (Nomade et al., 2005, Chemical Geology). Multiple-grain step-heating analyses using 3 to 5 steps were executed on several aliquots of the samples using a VG5400 noble gas mass spectrometer equipped with a 30W CO2 laser. Ages were calculated using the isochron method on all the steps run for each sample in order to avoid the necessity of assuming an initial composition and so all of the data points from a single irradiation could be plotted together. The results have yielded ages far younger than previously reported in all of the TVG, with very unradiogenic Ar and with 40Ar/36Ar intercepts that are mostly higher than the atmospheric ratio of 298.56±0.31 (Lee et al., 2006, Geochimica et Cosmochimica Acta). The second eruptive stage (using eruptive stages mapped by Lai et al., 2010, TAO) yielded ages in different locations of .053±.012Ma and .052±.014Ma. A third sample that was previously mapped in this stage yielded an age of .17±.03Ma. We have not yet been successful at obtaining reliable results on the stratigraphically youngest sample.

Does oral language underpin the development of later behavior problems? A longitudinal meta-analysis.

PubMed

Chow, Jason C; Ekholm, Erik; Coleman, Heather

2018-05-24

The purpose of this article is to estimate the overall weighted mean effect of the relation between early language skills and later behavior problems in school-aged children. A systematic literature search yielded 19,790 unduplicated reports, and a structured search strategy and identification procedure yielded 25 unique data sets, with 114 effect sizes for analysis. Eligible reports were then coded, and effect sizes were extracted and synthesized via robust variance estimation and random-effects meta-analytic techniques. The overall correlation between early language and later behavior problems was negative and small (r = -.14, 95% confidence interval [CI] [-.16, -.11]), and controlling for demographic variables did not reduce the magnitude of the inverse relationship between language skill and problem behavior (r = -.16). Moderator analyses identified receptive language, parent-reported behavior measures, gender, and age as significant predictors of the association between language and behavior. This article corroborates the consistent findings of previous meta-analytic and longitudinal studies and further identifies areas, particularly around measurement, for future research. Furthermore, prospective longitudinal evaluations of the relations between language deficits and behavior problems with different types of measures (teacher-/parent-report, direct assessment, classroom observation) is warranted. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Rooster semen cryopreservation: effect of pedigree line and male age on postthaw sperm function.

PubMed

Long, J A; Bongalhardo, D C; Pelaéz, J; Saxena, S; Settar, P; O'Sullivan, N P; Fulton, J E

2010-05-01

The fertility rates of cryopreserved poultry semen are highly variable and not reliable for use in preservation of commercial genetic stocks. Our objective was to evaluate the cryosurvival of semen from 8 pedigreed layer lines at 2 different ages: the onset and end of commercial production. Semen from 160 roosters (20/line) was frozen individually with 11% glycerol at 6 and 12 mo of age. Glycerol was removed from thawed semen by Accudenz gradient centrifugation. The viability of thawed sperm from each male was determined using fluorescent live-dead staining and flow cytometry; sperm velocity parameters were measured using computerized motion analysis. The fertilizing ability of thawed sperm was evaluated in vitro by assessing hydrolysis of the inner perivitelline membrane. The postthaw function of sperm from the elite lines varied widely, despite the fact that fresh semen from all of these lines typically yielded high fertility rates. The percentage of thawed sperm with intact plasma membranes ranged from 27.8 + or - 2.1 to 49.6 + or - 1.9 and varied among lines and between age groups. Thawed sperm from 2 lines consistently demonstrated the highest and lowest motility parameters, whereas the velocity parameters of the remaining 6 lines varied widely. The mean number of hydrolysis points per square millimeter of inner perivitelline membrane ranged from 12.5 + or - 4.1 (line 2) to 103.3 + or - 30.2 (line 6). Age effects were observed for 4 out of 8 lines; however, improved postthaw sperm function at 12 mo of age was not consistent for all 3 assays. These results demonstrate variability among pedigreed lines in withstanding glycerol-based semen cryopreservation and provide a model for delineating genotypic and phenotypic factors affecting sperm cryosurvival.

Reported Back Pain in Army Aircrew in Relation to Airframe, Gender, Age, and Experience.

PubMed

Kelley, Amanda M; MacDonnell, Jason; Grigley, Deahndra; Campbell, John; Gaydos, Steven J

2017-02-01

Back pain has remained an issue of significance among aircraft crewmembers for decades, occurring in the majority of military helicopter pilots with potential deleterious effects on performance, safety, and operational readiness. This exploratory, correlational survey study was designed to evaluate the presence of patterns and relationships that may require further examination to understand causal factors. The study population consisted of U.S. Army aviation crewmembers. Subjects (467) completed an anonymous survey, including questions regarding demographics, airframes, experience, pain history and severity, ergonomics, mitigation strategies, and duty limitations. Overall, 84.6% of participants reported back pain at some time during their flying career, with 77.8% reporting back pain in the last calendar year. Age was found to significantly correlate with earlier time to pain during flight, higher pain rating after flight, and occurrence of grounding. A stepwise linear regression model was used to explore the relationships between age, flight hours, and years of aviation experience, demonstrating age to be the significant variable accounting for the observed variance. Aircrew reported wear of combat-related survival equipment and poor lumbar support to be the most notable contributors. Back pain rates were consistent with previous studies. The relationship of age to back pain in this study may highlight unique pathophysiological pathways that should be further investigated within an occupational context to better understand the etiologic role. Enhanced seated lumbar support and combat-related survival equipment remain relatively low-cost/high-yield topics worthy of further investigation for exploiting efficient means to improve health, safety, and operational performance.Kelley AM, MacDonnell J, Grigley D, Campbell J, Gaydos SJ. Reported back pain in army aircrew in relation to airframe, gender, age, and experience. Aerosp Med Hum Perform. 2017; 88(2):96-103.

The effects of artificial aging on the microstructure and fracture toughness of Al-Cu-Li alloy 2195

NASA Astrophysics Data System (ADS)

Chen, P. S.; Kuruvilla, A. K.; Malone, T. W.; Stanton, W. P.

1998-10-01

Aluminum-lithium alloys have shown promise for aerospace applications, and National Aeronautics and Space Administration (NASA) has selected the aluminum-lithium Alloy 2195 for the main structural alloy of the super light weight tank (SLWT) for the space shuttle. This alloy has significantly higher strength than conventional 2xxx alloys (such as 2219) at both ambient and cryogenic temperatures. If properly processed and heat treated, this alloy can display higher fracture toughness at cryogenic temperature than at ambient temperature. However, the properties of production materials have shown greater variation than those of other established alloys, as is the case with any new alloy that is being transitioned to a demanding application. Recently, some commercial 2195 plates for the SLWT program were rejected, mostly due to low CFT or FTR at ambient and cryogenic temperatures. Investigation of the microstructure property relationships of Al-Cu-Li based alloys indicates that the poor fracture toughness properties can be attributed to excessive T1 precipitation at subgrain boundaries. Lowering the aging temperature is one way to avoid excessive T1 precipitation at subgrain boundaries. However, this approach results in a significant drop in yield strength. In addition, low-temperature aging is associated with sluggish aging kinetics, which are not desirable for industrial mass production. Therefore, the present study was undertaken to develop an aging process that can improve fracture toughness without sacrificing yield and tensile strength. A multistep heating-rate controlled (MSRC) aging treatment has been developed that can improve the cryogenic fracture toughness of aluminum-lithium Alloy 2195. At the same levels of yield strength (YS), this treatment results in considerably higher fracture toughness than that found in Alloy 2195, which has received conventional (isothermal) aging. Transmission electron microscopy revealed that the new treatment greatly reduces the size and density of subgrain-boundary T1 precipitates. In addition, it promotes T1 and θ" nucleation, resulting in a fine and dense distribution of precipitate particles in the matrix. The MSRC aging treatment consists of (a) aging at 127‡C (260‡F) for 5 h, (b) heating continuously from 127‡C (260‡F) to 135‡C (275‡F) at a rate of 0.556‡C/h (1‡F/h), (c) holding at 135‡C (275‡F) for 5 h, (d) heating continuously from 135 to 143‡C (275 to 290‡F) at a rate of 0.556‡C/h (1‡F/h), and (e) holding at 143‡C (290‡F) for 25 h to obtain a near peak-aged condition.

Linkages and Interactions Analysis of Major Effect Drought Grain Yield QTLs in Rice.

PubMed

Vikram, Prashant; Swamy, B P Mallikarjuna; Dixit, Shalabh; Trinidad, Jennylyn; Sta Cruz, Ma Teresa; Maturan, Paul C; Amante, Modesto; Kumar, Arvind

2016-01-01

Quantitative trait loci conferring high grain yield under drought in rice are important genomic resources for climate resilient breeding. Major and consistent drought grain yield QTLs usually co-locate with flowering and/or plant height QTLs, which could be due to either linkage or pleiotropy. Five mapping populations used for the identification of major and consistent drought grain yield QTLs underwent multiple-trait, multiple-interval mapping test (MT-MIM) to estimate the significance of pleiotropy effects. Results indicated towards possible linkages between the drought grain yield QTLs with co-locating flowering and/or plant height QTLs. Linkages of days to flowering and plant height were eliminated through a marker-assisted breeding approach. Drought grain yield QTLs also showed interaction effects with flowering QTLs. Drought responsiveness of the flowering locus on chromosome 3 (qDTY3.2) has been revealed through allelic analysis. Considering linkage and interaction effects associated with drought QTLs, a comprehensive marker-assisted breeding strategy was followed to develop rice genotypes with improved grain yield under drought stress.

Influence of conventional biochar and ageing biochar application to arable soil on soil fertility and plant yield

NASA Astrophysics Data System (ADS)

Dvořáčková, Helena; Záhora, Jaroslav; Elbl, Jakub; Kynický, Jindřich; Hladký, Jan; Brtnický, Martin

2017-04-01

Biochar represents very controversial material which is product of pyrolysis. According to many studies biochar has positive effect on physical and chemical properties such as pH, conductivity, aggregates stability etc. Unfortunately biochar is product of combustion, so it can content toxic substance as are aromatic compound. These substances may have a negative effect on yield and microbial activities in soil. Our aim was eliminated concentration of toxic compound but preserved positive effect of biochar on soil properties. We was ageing/ activating of biochar in water environment and for soil inoculum we used native soil from landscape. Moreover two types of biochar was tested by pot experiment with seven variants, where conventional biochar from residual biomass and ageing biochar were applied in different doses: 10 t/ha, 20t/ha and 50 t/ha. Pots were placed in green house for 90 days and after the end of experiment the following parameters of soil fertility, health and quality were evaluated: content of soil organic matter, arbuscular mycorrhizal colonisation of Lactuca sativa L. roots, leaching of mineral nitrogen, changes in plant available nutrient content, EC and pH. Above all the total yield of indicator plant was observed. The significant (P < 0.05) differences in plant yield and soil properties were found. The application of conventional biochar didn't have positive effect on plant yield in comparison with ageing biochar. The positive effect of ageing biochar addition on soil fertility was directly proportional to the dose which were applied - increasing in dose of ageing biochar resulted in increase of plant yield. Moreover the special experimental containers were used, where we was able to monitor the development of root in soil with and without addition of biochar (conventional or ageing). The positive influence of ageing biochar addition into soil on development of Lactuca sativa L. roots was observed.

Optically stimulated luminescence age controls on late Pleistocene and Holocene coastal lithosomes, North Carolina, USA

USGS Publications Warehouse

Mallinson, D.; Burdette, K.; Mahan, S.; Brook, G.

2008-01-01

Luminescence ages from a variety of coastal features on the North Carolina Coastal Plain provide age control for shoreline formation and relative sea-level position during the late Pleistocene. A series of paleoshoreline ridges, dating to Marine Isotope Stage (MIS) 5a and MIS 3 have been defined. The Kitty Hawk beach ridges, on the modern Outer Banks, yield ages of 3 to 2??ka. Oxygen-isotope data are used to place these deposits in the context of global climate and sea-level change. The occurrence of MIS 5a and MIS 3 shorelines suggests that glacio-isostatic adjustment (GIA) of the study area is large (ca. 22 to 26??m), as suggested and modeled by other workers, and/or MIS 3 sea level was briefly higher than suggested by some coral reef studies. Correcting the shoreline elevations for GIA brings their elevation in line with other sea-level indicators. The age of the Kitty Hawk beach ridges places the Holocene shoreline well west of its present location at ca. 3 to 2??ka. The age of shoreline progradation is consistent with the ages of other beach ridge complexes in the southeast USA, suggesting some regionally contemporaneous forcing mechanism. ?? 2007 University of Washington.

Taphonomic problems in reconstructing sea-level history from the late Quaternary marine terraces of Barbados

USGS Publications Warehouse

Muhs, Daniel; Simmons, Kathleen R.

2017-01-01

Although uranium series (U-series) ages of growth-position fossil corals are important to Quaternary sea-level history, coral clast reworking from storms can yield ages on a terrace dating to more than one high-sea stand, confounding interpretations of sea-level history. On northern Barbados, U-series ages corals from a thick storm deposit are not always younger with successively higher stratigraphic positions, but all date to the last interglacial period (~127 ka to ~112 ka), Marine Isotope Substage (MIS) 5.5. The storm deposit ages are consistent with the ages of growth-position corals found at the base of the section and at landward localities on this terrace. Thus, in this case, analysis of only a few corals would not have led to an error in interpreting sea-level history. In contrast, a notch cut into older Pleistocene limestone below the MIS 5.5 terrace contains corals that date to both MIS 5.5 (~125 ka) and MIS 5.3 (~108 ka). We infer that the notch formed during MIS 5.3 and the MIS 5.5 corals are reworked. Similar multiple ages of corals on terraces have been reported elsewhere on Barbados. Thus, care must be taken in interpreting U-series ages of corals that are reported without consideration of taphonomy.

The 40Ar/39Ar and K/Ar dating of lavas from the Hilo 1-km core hole, Hawaii Scientific Drilling Project

USGS Publications Warehouse

Sharp, W.D.; Turrin, B.D.; Renne, P.R.; Lanphere, M.A.

1996-01-01

Mauna Kea lava flows cored in the HilIo hole range in age from <200 ka to about 400 ka based on 40Ar/39Ar incremental heating and K-Ar analyses of 16 groundmass samples and one coexisting plagioclase. The lavas, all subaerially deposited, include a lower section consisting only of tholeiitic basalts and an upper section of interbedded alkalic, transitional tholeiitic, and tholeiitic basalts. The lower section has yielded predominantly complex, discordant 40Ar/39Ar age spectra that result from mobility of 40Ar and perhaps K, the presence of excess 40Ar, and redistribution of 39Ar by recoil. Comparison of K-Ar ages with 40Ar/39Ar integrated ages indicates that some of these samples have also lost 39Ar. Nevertheless, two plateau ages of 391 ?? 40 and 400 ?? 26 ka from deep in the hole, combined with data from the upper section, show that the tholeiitic section accumulated at an average rate of about 7 to 8 m/kyr and has an mean recurrence interval of 0.5 kyr/flow unit. Samples from the upper section yield relatively precise 40Ar/39Ar plateau and isotope correlation ages of 326 ?? 23, 241 ?? 5, 232 ?? 4, and 199 ?? 9 ka for depths of -415.7 m to -299.2 m. Within their uncertainty, these ages define a linear relationship with depth, with an average accumulation rate of 0.9 m/kyr and an average recurrence interval of 4.8 kyr/flow unit. The top of the Mauna Kea sequence at -280 m must be older than the plateau age of 132 ?? 32 ka, obtained for the basal Mauna Loa flow in the corehole. The upward decrease in lava accumulation rate is a consequence of the decreasing magma supply available to Mauna Kea as it rode the Pacific plate away from its magma source, the Hawaiian mantle plume. The age-depth relation in the core hole may be used to test and refine models that relate the growth of Mauna Kea to the thermal and compositional structure of the mantle plume.

A Pliocene chronostratigraphy for the Canadian western and high Arctic

NASA Astrophysics Data System (ADS)

Gosse, John; Braschi, Lea; Rybczynski, Natalia; Lakeman, Thomas; Zimmerman, Susan; Finkel, Robert; Barendregt, Rene; Matthews, John

2014-05-01

The Beaufort Formation comprises an extensive (1200 km long, more than 1 km thick) clastic wedge that formed during the Pliocene along the western Canadian Arctic Archipelago (CAA). In the western Arctic, the Ballast Brook (BB) site on Banks Is. exposes more than 20 km of section through the sandy and pebble sandy braided stream deposits with detrital organic beds. Farther north, Beaufort Fm fluvial and estuarine facies have been examined on Meighen Is. In the high Arctic, high terrace gravels (450 m high surface) at the Fyles Leaf Bed (FLB) and Beaver Pond (BP) sites on Ellesmere Is. are not considered part of the Beaufort Fm but have similar paleoenvironmental records. Fossil plant and faunal material from these sediments is often very well preserved and provides evidence of a boreal-type forest and peatlands. The BP fossil site preserves the remains of fossil vertebrates including fish, frog, horse, beaver, deerlet, and black bear, consistent with a boreal type forest habitat. The FLB site has recently yielded the first fossil evidence for a High Arctic camel, identified with the help of collagen fingerprinting from a fragmentary limb bone (tibia). Paleoenvironmental reconstruction of the Ellesmere sites has yielded a Mean Annual Temperature of between 14 to 22 degrees Celsius warmer than today. Minimum cosmogenic nuclide burial ages of 3.4 and 3.8 Ma obtained for the BP and FLB sites, respectively, are consistent with vertebrate and floral biostratigraphic evidence. The paleoenvironmental records from the Beaufort Fm in the western CAA sites have revealed a similar ecosystem with noteworthy differences in MAT and perhaps seasonality. New burial ages from Meighen Is. indicate a maximum age of 6.1 Ma, consistent with yet much older than previous age estimates, but supportive of paleomagnetic and biostratigraphy at the same location. The age differences may account for some of the interpreted variations in paleoenvironments, in addition to spatial differences in climate. The Beaufort Fm. appears to have filled at least the western portions of the ca. 100 km-wide channels that currently separate the islands of the CAA. Intervals of Pliocene continental-shelf progradation are recorded in the lower Iperk Fm, which is situated offshore and includes complex sigmoid-oblique clinoforms indicative of high-energy, coarse-clastic, deltaic sedimentation. A key objective of our research is to derive new age estimates and improved correlations among the Beaufort and Iperk Formations and high terrace gravels in order to test hypotheses to explain the nature of the dramatic landscape changes responsible for their deposition and the infilling of the CAA channels. If the channels of the modern CAA function as a heat source during winter months and a heat sink during summer months, infilling of the CAA channels and development of a broad coastal plain in the Pliocene may have shut down this radiative process, resulting in increased seasonality and continentality.

Control of growth of juvenile leaves of Eucalyptus globulus: effects of leaf age.

PubMed

Metcalfe, J C; Davies, W J; Pereira, J S

1991-12-01

Biophysical variables influencing the expansion of plant cells (yield threshold, cell wall extensibility and turgor) were measured in individual Eucalyptus globulus leaves from the time of emergence until cessation of growth. Leaf water relations variables and growth rates were determined as relative humidity was changed on an hourly basis. Yield threshold and cell wall extensibility were estimated from plots of leaf growth rate versus turgor. Cell wall extensibility was also measured by the Instron technique, and yield threshold was determined experimentally both by stress relaxation in a psychrometer chamber and by incubation in a range of polyethylene glycol solutions. Once emerging leaves reached approximately 5 cm(2) in size, increases in leaf area were rapid throughout the expansive phase and varied little between light and dark periods. Both leaf growth rate and turgor were sensitive to changes in humidity, and in the longer term, both yield threshold and cell wall extensibility changed as the leaf aged. Rapidly expanding leaves had a very low yield threshold and high cell wall extensibility, whereas mature leaves had low cell wall extensibility. Yield threshold increased with leaf age.

Hydrogeology of south-central St Croix, US Virgin Islands

USGS Publications Warehouse

Graves, R.P.

1995-01-01

The subsurface geology of south-central St. Croix consists of alluvium and underlying carbonate rocks. The alluvial deposits consist of sand and gravel with cobbles and boulders and, locally, thin lenses of silt and clay. The carbonate rocks consist of the Oligocene to Middle Miocene age Jealousy formation, the Miocene and Pliocene are Kingshill Limestone, and the Pliocene and younger age Post-Kingshill Carbonates. Ground water occurs under water-table conditions in the alluvial, Post-Kingshill Carbonates, and Kingshill Limestone deposits. These deposits are hydraulically connected and are considered to be a single hydrologic unit. The top of the water-table aquifer can range from 5 to 68 feet below land surface. The top of the Jealousy Formation is considered to be the bottom of the water- table aquifer and generally is from 85 to greater than 120 feet below land surface. Aquifer yields in south- central St. Croix can range from less than 5 gallons per minute to 80 gallons per minute. The ground- water in the study area is of the sodium-chloride type. Ground-water samples collected from selected wells had chloride concentrations ranging from 64 to 4,400 milligrams per liter, and dissolved solid concen- trations ranging from 619 to 7,540 milligrams per liter. Connate water is suspected as being the source of sodium chloride in the ground water.

Distortion-product otoacoustic emission reflection-component delays and cochlear tuning: estimates from across the human lifespan.

PubMed

Abdala, Carolina; Guérit, François; Luo, Ping; Shera, Christopher A

2014-04-01

A consistent relationship between reflection-emission delay and cochlear tuning has been demonstrated in a variety of mammalian species, as predicted by filter theory and models of otoacoustic emission (OAE) generation. As a step toward the goal of studying cochlear tuning throughout the human lifespan, this paper exploits the relationship and explores two strategies for estimating delay trends-energy weighting and peak picking-both of which emphasize data at the peaks of the magnitude fine structure. Distortion product otoacoustic emissions (DPOAEs) at 2f1-f2 were recorded, and their reflection components were extracted in 184 subjects ranging in age from prematurely born neonates to elderly adults. DPOAEs were measured from 0.5-4 kHz in all age groups and extended to 8 kHz in young adults. Delay trends were effectively estimated using either energy weighting or peak picking, with the former method yielding slightly shorter delays and the latter somewhat smaller confidence intervals. Delay and tuning estimates from young adults roughly match those obtained from SFOAEs. Although the match is imperfect, reflection-component delays showed the expected bend (apical-basal transition) near 1 kHz, consistent with a break in cochlear scaling. Consistent with other measures of tuning, the term newborn group showed the longest delays and sharpest tuning over much of the frequency range.

An evaluation of the zircon method of isotopic dating in the Southern Arabian Craton

USGS Publications Warehouse

Cooper, J.A.; Stacey, J.S.; Stoeser, D.G.; Fleck, R.J.

1979-01-01

A zircon study has been made on eleven samples of igneous rocks from the Saudi Arabian Craton. Ages of sized and magnetic fractions of zircon concentrates show variable degrees of discordance which seem to result from a very young disturbance that produces linear arrays in the Concordia plot. Model age calculations based on a statistically and geologically reasonable lower intercept produce very consistent internal relationships. The Pan African Orogeny, considered to be responsible for loss of radiogenic argon and strontium from minerals of many rocks, does not appear to have affected the zircon data, even though uplift had exposed the rocks of the Arabian Shield at that time. Tonalite, granodiorite, and crosscutting leucoadamellite bodies in the southern part of the An Nimas Bathylith yield ages in the time range 820-760 Ma. A narrow time range of 660 to 665 million years was indicated for ages of widely separated and compositionally different intrusive bodies all to the east of the An Nimas Bathylith. This work suggests that the younger end of the age spectrum established from regional K-Ar and Rb-Sr measurements may be underestimated, and that magmatic activity could be more episodic than previously assumed.

Foraminiferal faunal estimates of paleotemperature: Circumventing the no-analog problem yields cool ice age tropics

USGS Publications Warehouse

Mix, A.C.; Morey, A.E.; Pisias, N.G.; Hostetler, S.W.

1999-01-01

The sensitivity of the tropics to climate change, particularly the amplitude of glacial-to-interglacial changes in sea surface temperature (SST), is one of the great controversies in paleoclimatology. Here we reassess faunal estimates of ice age SSTs, focusing on the problem of no-analog planktonic foraminiferal assemblages in the equatorial oceans that confounds both classical transfer function and modern analog methods. A new calibration strategy developed here, which uses past variability of species to define robust faunal assemblages, solves the no-analog problem and reveals ice age cooling of 5??to 6??C in the equatorial current systems of the Atlantic and eastern Pacific Oceans. Classical transfer functions underestimated temperature changes in some areas of the tropical oceans because core-top assemblages misrepresented the ice age faunal assemblages. Our finding is consistent with some geochemical estimates and model predictions of greater ice age cooling in the tropics than was inferred by Climate: Long-Range Investigation, Mapping, and Prediction (CLIMAP) [1981] and thus may help to resolve a long-standing controversy. Our new foraminiferal transfer function suggests that such cooling was limited to the equatorial current systems, however, and supports CLIMAP's inference of stability of the subtropical gyre centers.

Does supplementation of beef calves by creep feeding systems influence milk production and body condition of the dams?

PubMed

Lopes, Sidnei Antônio; Paulino, Mário Fonseca; Detmann, Edenio; Valente, Ériton Egídio Lisboa; de Barros, Lívia Vieira; Rennó, Luciana Navajas; de Campos Valadares Filho, Sebastião; Martins, Leandro Soares

2016-08-01

The aim of this study was to evaluate the effects of beef calves' supplementation in creep feeding systems on milk yield, body weight (BW), and body condition score (BCS) of their dams on tropical pastures using a meta-analytical approach. The database was obtained from 11 experiments conducted between 2009 and 2014 in Brazil, totaling 485 observations (cows). The database consisted of 273 Nellore and 212 crossbred (7/8 Nellore × 1/8 Holstein) cows. All experiments were carried out in the suckling phase (from 3 to 8 months of age of calves) during the transition phase between rainy and dry seasons from February to June of different years. The data were analyzed by a meta-analytical approach using mixed models and taking into account random variation among experiments. Calves' supplementation (P ≥ 0.59) and the calves' sex (P ≥ 0.48) did not affect milk yield of cows. The average fat-corrected milk (FCM) yield was 6.71 and 6.83 kg/day for cows that had their calves supplemented and not supplemented, respectively. Differences were observed (P < 0.0001) for milk yield due to the genetic group where crossbred cows presented greater FCM yield (7.37 kg/day) compared with Nellore cows (6.17 kg/day). There was no effect of the calves' supplementation on BW change (P ≥ 0.11) and BCS change (P ≥ 0.23) of the cows. Therefore, it is concluded that supplementation of beef calves using creep feeding systems in tropical pastures does not affect milk yield, body weight, or body condition of their dams.

Developmental monitoring using caregiver reports in a resource-limited setting: the case of Kilifi, Kenya

PubMed Central

Abubakar, A; Holding, P; Van de Vijver, F; Bomu, G; Van Baar, A

2010-01-01

Aim: The main aim of the current study was to evaluate the reliability, validity and acceptability of developmental monitoring using caregiver reports among mothers in a rural African setting. Methods: A structured interview for parents of children aged 24 months and less was developed through both participant consultation and a review of literature. The reliability and validity of the schedule was evaluated through a 10-month monitoring programme of 95 children, aged 2–10 months. The acceptability of the process was evaluated by studying retention rates and by organizing focus group discussions with participating mothers. Results: The structured interview ‘Developmental Milestones Checklist’ consisted of 66 items covering three broad domains of child functioning: motor, language and personal–social development. The interview yielded scores of developmental achievements that showed high internal consistency and excellent test–retest reliability. The results were sensitive to maturational changes and nutritional deficiencies. In addition, acceptable retention rates of approximately 80% were found. Participating mothers reported that they found the procedures both acceptable and beneficial. Conclusion: Developmental monitoring using caregiver report is a viable method to identify and monitor at-risk children in Sub-Saharan Africa. PMID:20353499

The evolution of galaxies. III - Metal-enhanced star formation

NASA Technical Reports Server (NTRS)

Talbot, R. J., Jr.; Arnett, W. D.

1973-01-01

The problem of the paucity of low-metal-abundance low-mass stars is discussed. One alternative to the variable-initial-mass-function (VIMF) solution is proposed. It is shown that this solution - metal-enhanced star formation - satisfies the classical test which prompted the VIMF hypothesis. Furthermore, with no additional parameters it provides improved fits to other tests - e.g., inhomogeneities in the abundances in young stars, concordance of all nucleo-cosmochronologies, and a required yield of heavy-element production which is consistent with current stellar evolution theory. In this model the age of the Galaxy is 18.6 plus or minus 5.7 b.y.

Mid-Pliocene warm-period deposits in the High Arctic yield insight into camel evolution

PubMed Central

Rybczynski, Natalia; Gosse, John C.; Richard Harington, C.; Wogelius, Roy A.; Hidy, Alan J.; Buckley, Mike

2013-01-01

The mid-Pliocene was a global warm period, preceding the onset of Quaternary glaciations. Here we use cosmogenic nuclide dating to show that a fossiliferous terrestrial deposit that includes subfossil trees and the northern-most evidence of Pliocene ice wedge casts in Canada’s High Arctic (Ellesmere Island, Nunavut) was deposited during the mid-Pliocene warm period. The age estimates correspond to a general maximum in high latitude mean winter season insolation, consistent with the presence of a rich, boreal-type forest. Moreover, we report that these deposits have yielded the first evidence of a High Arctic camel, identified using collagen fingerprinting of a fragmentary fossil limb bone. Camels originated in North America and dispersed to Eurasia via the Bering Isthmus, an ephemeral land bridge linking Alaska and Russia. The results suggest that the evolutionary history of modern camels can be traced back to a lineage of giant camels that was well established in a forested Arctic. PMID:23462993

Trajectories of the home learning environment across the first 5 years: associations with children's vocabulary and literacy skills at prekindergarten.

PubMed

Rodriguez, Eileen T; Tamis-LeMonda, Catherine S

2011-01-01

Children's home learning environments were examined in a low-income sample of 1,852 children and families when children were 15, 25, 37, and 63 months. During home visits, children's participation in literacy activities, the quality of mothers' engagements with their children, and the availability of learning materials were assessed, yielding a total learning environment score at each age. At 63 months, children's vocabulary and literacy skills were assessed. Six learning environment trajectories were identified, including environments that were consistently low, environments that were consistently high, and environments characterized by varying patterns of change. The skills of children at the extremes of learning environment trajectories differed by more than 1 SD and the timing of learning experiences related to specific emerging skills. © 2011 The Authors. Child Development © 2011 Society for Research in Child Development, Inc.

Radiocarbon dating of planktonic foraminifer shells: A cautionary tale

NASA Astrophysics Data System (ADS)

Mekik, Figen

2014-01-01

rate, bioturbation, winnowing, and calcite dissolution produce significant radiocarbon age offsets among multiple species of coexisting planktonic foraminifers and pteropod fragments. We compare the radiocarbon age of foraminifer species and pteropod fragments with estimates of percent calcite dissolved made with a sedimentary proxy (Globorotalia menardii fragmentation index—MFI) to delineate the effect of dissolution on radiocarbon age of foraminifers. Data from two core top transects on the Rio Grande Rise (RIO) and Ontong Java Plateau (OJP) and from down core sediments of varying sedimentation rates in the tropical Pacific (ME-27, MD98 2177, and MW91-9 56GGC) reveal that sediments with the greatest accumulation rates produce the least age offsets among coexisting species. Age offsets among coexisting foraminifers are about 3500 years on RIO, and 1000 years on OJP. Two core tops from RIO yield an age of the Last Glacial Maximum possibly due to mass displacement of younger sediments downslope. Foraminifer age increases with increasing dissolution and there is a consistent pattern of older foraminifer fragments coexisting with younger whole shells of the same species. The only exception is sediments which have experienced high dissolution where fragments are younger than whole shells. The age offset between fragments of G. menardii and its coexisting whole shells does not exceed the age offset among other coexisting foraminifer species in the same core tops.

Eclogitization on the way up: Lu-Hf garnet chronology of metasomatic ultrahigh-pressure rocks from the Western Gneiss Complex, Norway

NASA Astrophysics Data System (ADS)

Cutts, J.; Smit, M. A.; Vrijmoed, J. C.

2016-12-01

The Western Gneiss Complex (WGC) is a fragment of continental crust that was subjected to high- and ultrahigh pressure (HP; UHP) conditions as a result of Caledonian continental collision (420-400 Ma). Most eclogite lenses and related high-pressure rocks have yielded petrological and chronological results that are consistent with a generalized model of Caledonian continental subduction. A distinct suite of eclogitic rocks - metasomatized (`Caledonized') Fe-Ti meta-peridotites - indicate extreme pressure conditions that do not fit the regional field gradient. The timing of these excursions is critical to their interpretation; however, so far limited age constraints exist for these rocks. In this study, we subject one such rock - the Magerøy orthopyroxene eclogite on the island of Otrøy - to Lu-Hf garnet chronology; a method that provides precise and robust data for garnet even at extreme temperatures. Conventional barometry indicates equilibration of the main garnet-bearing assemblage at c. 4.3 GPa and garnet geochronology yielded a date of c. 390 Ma. This result overlaps with Sm-Nd garnet and U-Pb zircon ages from the nearby diamond-bearing Svartberget peridotite body and leucosomes in its host gneiss. However, the age is ≥ 10 Ma younger than age data for most other eclogite lenses in WGC and corresponds to a time when the terrane was already exhumed to 30-35 km depth. The discrepancy in P-T-t evolution between the bulk of the WGC, and the (ultra-) mafic rocks at Magerøy and Svartberget indicates that the latter rocks reflect localized fluid-induced re-equilibration at pressures higher than lithostatic. The new data provide new support for the occurrence of this phenomenon in subducted continental crust undergoing exhumation and partial melting.

Origin of northern Gondwana Cambrian sandstone revealed by detrital zircon SHRIMP dating

USGS Publications Warehouse

Avigad, D.; Kolodner, K.; McWilliams, M.; Persing, H.; Weissbrod, T.

2003-01-01

Voluminous Paleozoic sandstone sequences were deposited in northern Africa and Arabia following an extended Neoproterozoic orogenic cycle that culminated in the assembly of Gondwana. We measured sensitive high-resolution ion microprobe (SHRIMP) U-Pb ages of detrital zircons separated from several Cambrian units in the Elat area of southern Israel in order to unravel their provenance. This sandstone forms the base of the widespread siliciclastic section now exposed on the periphery of the Arabian-Nubian shield in northeastern Africa and Arabia. Most of the detrital zircons we analyzed yielded Neoproterozoic concordant ages with a marked concentration at 0.55–0.65 Ga. The most likely provenance of the Neoproterozoic detritus is the Arabian-Nubian shield; 0.55–0.65 Ga was a time of posttectonic igneous activity, rift-related volcanism, and strike-slip faulting there. Of the zircons, 30% yielded pre-Neoproterozoic ages grouped at 0.9–1.1 Ga (Kibaran), 1.65–1.85 Ga, and 2.45–2.7 Ga. The majority of the pre-Neoproterozoic zircons underwent Pb loss, possibly as a consequence of the Pan-African orogeny resetting their provenance. Rocks of the Saharan metacraton and the southern Afif terrane in Saudi Arabia (∼1000 km south of Elat) are plausible sources of these zircons. Kibaran basement rocks are currently exposed more than 3000 km south of Elat (flanking the Mozambique belt), but the shape of the detrital zircons of that age and the presence of feldspar in the host sandstone are not fully consistent with such a long-distance transport. Reworking of Neoproteorozoic glacial detritus may explain the presence of Kibaran detrital zircons in the Cambrian of Elat, but the possibility that the Arabian-Nubian shield contains Kibaran rocks (hitherto not recognized) should also be explored.

Endogenous ROS levels in C. elegans under exogenous stress support revision of oxidative stress theory of life-history tradeoffs.

PubMed

Smith, Samson W; Latta, Leigh C; Denver, Dee R; Estes, Suzanne

2014-07-24

The oxidative stress theory of life-history tradeoffs states that oxidative stress caused by damaging free radicals directly underpins tradeoffs between reproduction and longevity by altering the allocation of energetic resources between these tasks. We test this theory by characterizing the effects of exogenous oxidative insult and its interaction with thermal stress and diet quality on a suite of life-history traits and correlations in Caenorhabditis elegans nematodes. We also quantify demographic aging rates and endogenous reactive oxygen species (ROS) levels in live animals. Our findings indicate a tradeoff between investment in reproduction and antioxidant defense (somatic maintenance) consistent with theoretical predictions, but correlations between standard life-history traits yield little evidence that oxidative stress generates strict tradeoffs. Increasing oxidative insult, however, shows a strong tendency to uncouple positive phenotypic correlations and, in particular, to reduce the correlation between reproduction and lifespan. We also found that mild oxidative insult results in lower levels of endogenous ROS accompanied by hormetic changes in lifespan, demographic aging, and reproduction that disappear in combined-stress treatments--consistent with the oxidative stress theory of aging. Our findings demonstrate that oxidative stress is a direct contributor to life-history trait variation and that traditional tradeoffs are not necessary to invoke oxidative stress as a mediator of relationships between life-history traits, supporting previous calls for revisions to theory.

Endogenous ROS levels in C. elegans under exogenous stress support revision of oxidative stress theory of life-history tradeoffs

PubMed Central

2014-01-01

Background The oxidative stress theory of life-history tradeoffs states that oxidative stress caused by damaging free radicals directly underpins tradeoffs between reproduction and longevity by altering the allocation of energetic resources between these tasks. We test this theory by characterizing the effects of exogenous oxidative insult and its interaction with thermal stress and diet quality on a suite of life-history traits and correlations in Caenorhabditis elegans nematodes. We also quantify demographic aging rates and endogenous reactive oxygen species (ROS) levels in live animals. Results Our findings indicate a tradeoff between investment in reproduction and antioxidant defense (somatic maintenance) consistent with theoretical predictions, but correlations between standard life-history traits yield little evidence that oxidative stress generates strict tradeoffs. Increasing oxidative insult, however, shows a strong tendency to uncouple positive phenotypic correlations and, in particular, to reduce the correlation between reproduction and lifespan. We also found that mild oxidative insult results in lower levels of endogenous ROS accompanied by hormetic changes in lifespan, demographic aging, and reproduction that disappear in combined-stress treatments--consistent with the oxidative stress theory of aging. Conclusions Our findings demonstrate that oxidative stress is a direct contributor to life-history trait variation and that traditional tradeoffs are not necessary to invoke oxidative stress as a mediator of relationships between life-history traits, supporting previous calls for revisions to theory. PMID:25056725

Ages of pre-rift basement and synrift rocks along the conjugate rift and transform margins of the Argintine Precordillera and Laurentia

USGS Publications Warehouse

Thomas, William A.; Tucker, Robert D.; Astini, Ricardo A.; Denison, Rodger E.

2012-01-01

New geochronologic data from basement rocks support the interpretation that the Argentine Precordillera (Cuyania) terrane was rifted from the Ouachita embayment of the Iapetan margin of Laurentia. New data from the Ozark dome show a range of ages in two groups at 1466 ± 3 to 1462 ± 1 Ma and 1323 ± 2 to 1317 ± 2 Ma, consistent with existing data for the Eastern Granite-Rhyolite province and Southern Granite-Rhyolite province, respectively. Similarly, a newly determined age of 1364 ± 2 Ma for the Tishomingo Granite in the Arbuckle Mountains confirms previously published analyses for this part of the Southern Granite-Rhyolite province. Along with previously reported ages from basement olistoliths in Ordovician slope deposits in the Ouachita embayment, the data for basement ages support the interpretation that rocks of the Southern Granite-Rhyolite province form the margin of Laurentian crust around the corner of the Ouachita embayment, which is bounded by the Ouachita rift and Alabama-Oklahoma transform fault. In contrast, both west and east of the corner of the Ouachita embayment, Grenville-Llano basement (approximately 1325–1000 Ma) forms the rifted margin of Laurentia. New U/Pb zircon data from basement rocks in the southern part of the Argentine Precordillera indicate crystallization ages of 1205 ± 1 Ma and 1204 ± 2 Ma, consistent with previously reported ages (approximately 1250–1000 Ma) of basement rocks from other parts of the Precordillera. These data document multiple events within the same time span as multiple events in the Grenville orogeny in eastern Laurentia, and are consistent with Grenville-age rocks along the conjugate margins of the Precordillera and Laurentia. Ages from one newly analyzed collection, however, are older than those from other basement rocks in the Precordillera. These ages, from granodioritic-granitic basement clasts in a conglomerate olistolith in Ordovician slope deposits, are 1370 ± 2 Ma and 1367 ± 5 Ma. These older ages from the Precordillera are consistent with indications that the Iapetan margin in the Ouachita embayment of Laurentia truncated the Grenville front and left older rocks of the Southern Granite-Rhyolite province (1390–1320 Ma) at the rifted margin. Chronostratigraphic correlations of synrift and post-rift sedimentary deposits on the Precordillera and on the Texas promontory of Laurentia document initial rifting in the Early Cambrian. Previously published data from synrift plutonic and volcanic rocks in the Wichita and Arbuckle Mountains along the transform-parallel intracratonic Southern Oklahoma fault system inboard from the Ouachita embayment document crystallization ages of 539–530 Ma. New data from synrift volcanic rocks in the Arbuckle Mountains in the eastern part of the Southern Oklahoma fault system yield ages of 539 ± 5 Ma and 536 ± 5 Ma, confirming the age of synrift volcanism.

Erosional history of the Appalachians as recordeed in detrital zircon fission-track ages and lithic detritus in Atlantic Coastal Plain sediments

USGS Publications Warehouse

Naeser, C.W.; Naeser, N.D.; Edwards, Lucy E.; Weems, Robert E.; Southworth, C. Scott; Newell, Wayne L.

2016-01-01

Comparison of fission-track (FT) ages of detrital zircons recovered from Atlantic Coastal Plain sediments to FT ages of zircons from bedrock in source terranes in the Appalachians provides a key to understanding the provenance of the sediments and, in turn, the erosional and depositional history of the Atlantic passive margin.In Appalachian source terranes, the oldest zircon fission-track (ZFT) ages from bedrock in the western Appalachians (defined for this paper as the Appalachian Plateau, Valley and Ridge, and far western Blue Ridge) are notably older than the oldest ages from bedrock in the eastern Appalachians (Piedmont and main part of the Blue Ridge). The age difference is seen both in ZFT sample ages and in individual zircon grain ages and reflects differences in the thermotectonic history of the rocks. In the east, ZFT data indicate that the rocks cooled from temperatures high enough to partially or totally reset ZFT ages during the Paleozoic and (or) Mesozoic. The majority of the rocks are interpreted to have cooled through the ZFT closure temperature (∼235 °C) at various times during the late Paleozoic Alleghanian orogeny. In contrast, most of the rocks sampled in the western Appalachians have never been heated to temperatures high enough to totally reset their ZFT ages. Reflecting their contrasting thermotectonic histories, nearly 80 percent of the sampled western rocks yield one or more zircon grains with very old FT ages, in excess of 800 Ma; zircon grains yielding FT ages this old have not been found in rocks in the Piedmont and main part of the Blue Ridge. The ZFT data suggest that the asymmetry of zircon ages of exposed bedrock in the eastern and western Appalachians was in evidence by no later than the Early Cretaceous and probably by the Late Triassic.Detrital zircon suites from sands collected in the Atlantic Coastal Plain provide a record of detritus eroded from source terranes in the Appalachians during the Mesozoic and Cenozoic. In Virginia and Maryland, sands of Early Cretaceous through late early Oligocene age do not yield any old zircons comparable in age to the old zircons found in bedrock in the western Appalachians. Very old zircons yielding FT ages >800 Ma are only encountered in Coastal Plain sands of middle early Miocene and younger age.Miocene and younger fluvial-deltaic deposits associated with the major mid-Atlantic Coastal Plain rivers that now head in the western Appalachians (the Hudson, Delaware, Susquehanna, Potomac, James, and Roanoke) contain abundant clasts of fossiliferous chert and quartzite and other distinctive rock types derived from Paleozoic rocks of the western Appalachians. These distinctive clasts have not been reported in older Coastal Plain sediments.The ZFT and lithic detritus data indicate that the drainage divide for one or more east-flowing mid-Atlantic rivers migrated west into the western Appalachians, and the river(s) began transporting western Appalachian detritus to the Atlantic Coastal Plain, sometime between the late early Oligocene and middle early Miocene. By no later than late middle Miocene most if not all of the major rivers that now head west of the Blue Ridge were transporting western Appalachian detritus to the Coastal Plain. Prior to the drainage divide migrating into the western Appalachians, the ZFT data are consistent with the dominant source of Atlantic Coastal Plain sediments being detritus from the Piedmont and main part of the Blue Ridge, with possible input from distant volcanic sources.The ZFT data suggest that the rapid increase in the rate of siliciclastic sediment accumulation in middle Atlantic margin offshore basins that peaked in the middle Miocene and produced almost 30 percent of the total volume of post-rift siliciclastic sediments in the offshore basins began in the early Miocene when Atlantic river(s) gained access to the relatively easily eroded Paleozoic sedimentary rocks of the western Appalachians.

Zircon Messengers Reveal the Age and History of Great Basin Crust, Kern Mountains, Nevada

NASA Astrophysics Data System (ADS)

Gottlieb, E. S.; Miller, E. L.; Wooden, J. L.

2011-12-01

Results of SHRIMP-RG analyses of complexly zoned zircons from muscovite-bearing granitic rocks exposed in the Kerns Mountains of East-Central Nevada constrain the timing, duration, and loci of zircon growth within the interior of the U.S. Cordillera during Late Cretaceous through Eocene time. The Kern Mountains are an exhumed block of greenschist to amphibolite facies metamorphosed miogeoclinal rocks that were pervasively intruded by the Late Cretaceous Tungstonia granite pluton and the Eocene Skinner Canyon and Uvada plutons (Best et al., 1974). Euhedral zircons separated from a coarse-grained (2-3 cm) muscovite-bearing phase of the Tungstonia pluton exhibit complex cathodeluminescence (CL) zonation. Sub-angular to sub-rounded cores with highly variable CL are overgrown by oscillatory-zoned zircon which in turn is rimmed by dark CL zircon (U>5000 ppm). A weighted mean Pb/U age of 70.2±0.9 Ma (n=20, MSWD=2.5) obtained from the oscillatory-zoned zircon coincides with the end of Cretaceous peak metamorphism at shallow crustal levels. Pb/U ages from core zones (n=18) predominantly are 0.9-1.4 Ga (n=11; 7 of which <15% discordant) or 2.4-2.7 Ga (n=5; 1 of which <15% discordant), consistent with ages of detrital zircons within the Late Proterozoic McCoy Creek Group exposed in adjacent ranges. A previously undated muscovite-bearing dike in Skinner Canyon yielded a texturally complex population of subhedral zircon grains. CL imaging of these grains reveals fragmental, ghost-like cores surrounded by irregularly shaped overgrowth zones with diffuse boundaries which are rimmed by oscillatory-zoned zircon. Both oscillatory zoned and gradational rim areas (n=32) yielded Late Cretaceous to Eocene ages. Twelve spots define the age of intrusion at 41.7±0.3 Ma (MSWD=1.8), consistent with the local onset of Eocene magmatism. An older period of zircon growth from ~75-45 Ma, coincident with the proposed duration of the Laramide shallow slab, is defined by zircon with flat to shallow HREE patterns and systematically increasing Yb content through time (n=16). Zircon defining a slightly older growth period (85-90 Ma, n=4) is geochemically distinct (>>Yb content, steep HREE slope). Within the cores, Pb/U ages cluster around 1.55-1.68 Ga (n=9) and 2.28-2.48 Ga (n=8) with concordia upper intercepts at 1.68 and 2.45 Ga respectively. The younger age is consistent with widespread magmatism in the SW U.S. (Whitmeyer and Karlstrom, 2007) and the older with intrusion of the nearby Chimney Rock orthogneiss in the East Humboldt Range (W.R. Premo, unpub.). These data imply the Tungstonia was partially derived from a shallow (detrital) source, while the dike assimilated deeper (basement) sources. Trace element geochemistry and CL-inferred textures of the ~75-45 Ma span of zircon growth in the dike reveal a prolonged period of near-zircon solidus conditions in the lower crust, curtailed by assimilation into Eocene intrusions. Coupling age and geochemistry of the xenocrystic areas of complexly zoned zircons provides a powerful tool for understanding the timing and conditions of the crustal evolution processes.

Hunting for eruption ages in accessory minerals

NASA Astrophysics Data System (ADS)

Vazquez, J. A.

2012-12-01

A primary goal in geochronology is to provide precise and accurate ages for tephras that serve as chronostratigraphic markers for constraining the timing and rates of volcanism, sedimentation, climate change, and catastrophic events in Earth history. Zircon remains the most versatile accessory mineral for dating silicic tephras due to its common preservation in distal pyroclastic deposits, as well as the robustness of its U-Pb and U-series systems even after host materials have been hydrothermally altered or weathered. Countless studies document that zircon may be complexly zoned in age due to inheritance, contamination, recycling of antecrysts, protracted crystallization in long-lived magma reservoirs, or any combination of these. Other accessory minerals such as allanite or chevkinite can retain similar records of protracted crystallization. If the goal is to date the durations of magmatic crystallization, differentiation, and/or magma residence, then these protracted chronologies within and between accessory minerals are a blessing. However, if the goal is to date the timing of eruption with high precision, i.e., absolute ages with millennial-scale uncertainties, then this age zoning is a curse. Observations from ion microprobe 238U-230Th dating of Pleistocene zircon and allanite provide insight into the record of near-eruption crystallization in accessory minerals and serve as a guide for high-precision whole-crystal dating. Although imprecise relative to conventional techniques, ion probe analysis allows high-spatial resolution 238U-230Th dating that can document multi-millennial age distributions at the crystal scale. Analysis of unpolished rims and continuous depth profiling of zircon from small and large volume eruptions (e.g., Coso, Mono Craters, Yellowstone) reveals that the final several micrometers of crystallization often yield ages that are indistinguishable from associated eruption ages from the 40Ar/39Ar or (U-Th)/He methods. Using this approach, we have derived relatively precise (± ~ 5%, 2σ) U-Th isochron ages from the unpolished rims of pumice-derived allanite and zircon from late Pleistocene Wilson Creek Formation tephras in eastern California, whose ages are controversial and have been difficult to resolve via 40Ar/39Ar and radiocarbon dating. Allanite and zircon rims from Ashes 7-19 in the lower portion of Wilson Creek sediments yield stratigraphically consistent ages of ca. 27 ka to ca. 62 ka, with a minority of crystals identifiable as xenocrysts from early Mono Craters rhyolites. Model ages for the interiors of allanite crystals are mostly < 10 k.y. older than their rims. Tephra deposited during the geomagnetic excursion debated to be either the Mono Lake or Laschamp event yields a rim isochron age of ca. 41 ka. This age is indistinguishable from an independent age of 41 ka derived at the latter excursion's type locality in France (Singer et al., 2009) as well as from age-models for deep-sea sediments. The results are in excellent agreement with a previously determined chronology derived from magnetostratigraphy (Zimmerman et al., 2006). Refs: Singer et al., 2009, EPSL 286: 80-88; Zimmerman et al., 2006, EPSL 252: 94-106

The Load and Time Dependence of Chemical Bonding-Induced Frictional Ageing of Silica at the Nanoscale

NASA Astrophysics Data System (ADS)

Tian, K.; Gosvami, N. N.; Goldsby, D. L.; Carpick, R. W.

2015-12-01

Rate and state friction (RSF) laws are empirical relationships that describe the frictional behavior of rocks and other materials in experiments, and reproduce a variety of observed natural behavior when employed in earthquake models. A pervasive observation from rock friction experiments is the linear increase of static friction with the log of contact time, or 'ageing'. Ageing is usually attributed to an increase in real area of contact associated with asperity creep. However, recent atomic force microscopy (AFM) experiments demonstrate that ageing of nanoscale silica-silica contacts is due to progressive formation of interfacial chemical bonds in the absence of plastic deformation, in a manner consistent with the multi-contact ageing behavior of rocks [Li et al., 2011]. To further investigate chemical bonding-induced ageing, we explored the influence of normal load (and thus contact normal stress) and contact time on ageing. Experiments that mimic slide-hold-slide rock friction experiments were conducted in the AFM for contact loads and hold times ranging from 23 to 393 nN and 0.1 to 100 s, respectively, all in humid air (~50% RH) at room temperature. Experiments were conducted by sequentially sliding the AFM tip on the sample at a velocity V of 0.5 μm/s, setting V to zero and holding the tip stationary for a given time, and finally resuming sliding at 0.5 μm/s to yield a peak value of friction followed by a drop to the sliding friction value. Chemical bonding-induced ageing, as measured by the peak friction minus the sliding friction, increases approximately linearly with the product of normal load and the log of the hold time. Theoretical studies of the roles of reaction energy barriers in nanoscale ageing indicate that frictional ageing depends on the total number of reaction sites and the hold time [Liu & Szlufarska, 2012]. We combine chemical kinetics analyses with contact mechanics models to explain our results, and develop a new approach for curve fitting ageing vs. load data which shows that the friction drop data points all fall on a master curve. The analysis yields physically reasonable values for the activation energy and activation volume of the chemical bonding process. Our study provides a basis to hypothesize that the kinetic processes in chemical bonding-induced ageing do not depend strongly on normal load.

Knowledge-Guided Robust MRI Brain Extraction for Diverse Large-Scale Neuroimaging Studies on Humans and Non-Human Primates

PubMed Central

Wang, Yaping; Nie, Jingxin; Yap, Pew-Thian; Li, Gang; Shi, Feng; Geng, Xiujuan; Guo, Lei; Shen, Dinggang

2014-01-01

Accurate and robust brain extraction is a critical step in most neuroimaging analysis pipelines. In particular, for the large-scale multi-site neuroimaging studies involving a significant number of subjects with diverse age and diagnostic groups, accurate and robust extraction of the brain automatically and consistently is highly desirable. In this paper, we introduce population-specific probability maps to guide the brain extraction of diverse subject groups, including both healthy and diseased adult human populations, both developing and aging human populations, as well as non-human primates. Specifically, the proposed method combines an atlas-based approach, for coarse skull-stripping, with a deformable-surface-based approach that is guided by local intensity information and population-specific prior information learned from a set of real brain images for more localized refinement. Comprehensive quantitative evaluations were performed on the diverse large-scale populations of ADNI dataset with over 800 subjects (55∼90 years of age, multi-site, various diagnosis groups), OASIS dataset with over 400 subjects (18∼96 years of age, wide age range, various diagnosis groups), and NIH pediatrics dataset with 150 subjects (5∼18 years of age, multi-site, wide age range as a complementary age group to the adult dataset). The results demonstrate that our method consistently yields the best overall results across almost the entire human life span, with only a single set of parameters. To demonstrate its capability to work on non-human primates, the proposed method is further evaluated using a rhesus macaque dataset with 20 subjects. Quantitative comparisons with popularly used state-of-the-art methods, including BET, Two-pass BET, BET-B, BSE, HWA, ROBEX and AFNI, demonstrate that the proposed method performs favorably with superior performance on all testing datasets, indicating its robustness and effectiveness. PMID:24489639

Dating exhumed peridotite with spinel (U-Th)/He chronometry

NASA Astrophysics Data System (ADS)

Cooperdock, Emily H. G.; Stockli, Daniel F.

2018-05-01

The timing of cooling and exhumation of mantle peridotites in oceanic and continental settings has been challenging to determine using traditional geo- and thermochronometric techniques. Hence, the timing of the exhumation of mantle rocks to the Earth's surface at mid-ocean ridges, rifted and passive continental margins, and within continental volcanic and orogenic systems has remained largely elusive or only loosely constrained by relative age bracketing. Magmatic spinel [(Mg, Fe)(Al,Cr)2O4] is a ubiquitous primary mineral phase in mantle peridotites and is often the only primary mineral phase to survive surface weathering and serpentinization. This work explores spinel (U-Th)/He thermochronology as a novel tool to directly date the exhumation and cooling history of spinel-bearing mantle peridotite. Samples were chosen from a range of tectonic and petrologic settings, including a mid-ocean ridge abyssal peridotite (ODP Leg 209), an orogenic tectonic sliver of sub-continental mantle (Lherz massif, France), and a volcanic-rock hosted mantle xenolith (Green Knobs, NM). Spinel grains were selected based on grain size and morphology, screened for internal homogeneity using X-ray computed tomography, and air abraded to eliminate effects of alpha ejection/implantation. These case studies yield spinel He age results that are reproducible and generally in good agreement with independent age constraints. For ODP Leg 209, a spinel He age of 1.1 ± 0.3 Ma (2 SE) (n = 8) is consistent with independent U-Pb and magnetic anomaly ages for the exhumation of oceanic crust by detachment faulting along this segment of the slow-spreading ridge. Spinel from the Lherz massif yield He ages from 60-70 Ma (n = 3), which correspond well with independent thermochronometric constraints for cooling associated with Pyrenean collisional exhumation. Spinel from a mantle xenolith within a previously undated kimberlite diatreme at Green Knobs, New Mexico, generate a reproducible mean He age of 11.7 ± 1.8 Ma (2 SE) (n = 6) that appears to record young volcanism in the area or age resetting by post-emplacement re-heating or alteration. The combined results of these case studies demonstrate the viability for spinel He thermochronometry to resolve cooling histories of peridotite exhumed through tectonic and volcanic processes.

High Energy Explosive Yield Enhancer Using Microencapsulation.

DTIC Science & Technology

The invention consists of a class of high energy explosive yield enhancers created through the use of microencapsulation techniques. The... microcapsules consist of combinations of highly reactive oxidizers that are encapsulated in either passivated inorganic fuels or inert materials and inorganic...fuels. Depending on the application, the availability of the various oxidizers and fuels within the microcapsules can be customized to increase the

Flux line relaxation kinetics following current quenches in disordered type-II superconductors

NASA Astrophysics Data System (ADS)

Chaturvedi, Harshwardhan; Assi, Hiba; Dobramysl, Ulrich; Pleimling, Michel; Täuber, Uwe

We describe the disordered vortex system in type-II superconductors with an elastic line model, whose dynamics we investigate numerically by means of Langevin Molecular Dynamics. A system of driven interacting flux lines in a sample with randomly distributed point pinning centers is subjected to drive quench from a moving non-equilibrium steady state into one of three regimes viz. moving (steady state), pinned (glassy) or depinning (critical). The first yields fast exponential relaxation to the new non-equilibrium stationary state while the second displays algebraically slow relaxation and aging scaling with non-universal exponents. Our most recent work consists of aging and finite temperature scaling studies for drive quenches into the critical depinning regime. This research is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-FG02-09ER46613.

Site index, height growth, normal yields and stocking levels for larch in Oregon and Washington.

Treesearch

P.H. Cochran

1985-01-01

Even-aged stands of larch in Oregon and Washington have cubic volume yields similar to yields from larch in Idaho and Montana. Site index values derived from the heights of the single tallest tree on 1/5-acre plots at an age at breast height of 50 years range from 50 to 110 feet. These values have the same index to productivity as the site index values of 30 to 90 feet...

Midwest agriculture and ENSO: A comparison of AVHRR NDVI3g data and crop yields in the United States Corn Belt from 1982 to 2014

NASA Astrophysics Data System (ADS)

Glennie, Erin; Anyamba, Assaf

2018-06-01

A time series of Advanced Very High Resolution Radiometer (AVHRR) derived normalized difference vegetation index (NDVI) data were compared to National Agricultural Statistics Service (NASS) corn yield data in the United States Corn Belt from 1982 to 2014. The main objectives of the comparison were to assess 1) the consistency of regional Corn Belt responses to El Niño/Southern Oscillation (ENSO) teleconnection signals, and 2) the reliability of using NDVI as an indicator of crop yield. Regional NDVI values were used to model a seasonal curve and to define the growing season - May to October. Seasonal conditions in each county were represented by NDVI and land surface temperature (LST) composites, and corn yield was represented by average annual bushels produced per acre. Correlation analysis between the NDVI, LST, corn yield, and equatorial Pacific sea surface temperature anomalies revealed patterns in land surface dynamics and corn yield, as well as typical impacts of ENSO episodes. It was observed from the study that growing seasons coincident with La Niña events were consistently warmer, but El Niño events did not consistently impact NDVI, temperature, or corn yield data. Moreover, the El Niño and La Niña composite images suggest that impacts vary spatially across the Corn Belt. While corn is the dominant crop in the region, some inconsistencies between corn yield and NDVI may be attributed to soy crops and other background interference. The overall correlation between the total growing season NDVI anomaly and detrended corn yield was 0.61(p = 0.00013), though the strength of the relationship varies across the Corn Belt.

A-type granites from the Guéra Massif, Central Chad: Petrology, geochemistry, geochronology, and petrogenesis.

NASA Astrophysics Data System (ADS)

Pham, Ngoc Ha T.; Shellnutt, J. Gregory; Yeh, Meng-Wan; Lee, Tung-Yi

2017-04-01

The poorly studied Saharan Metacraton of North-Central Africa is located between the Arabian-Nubian Shield in the east, the Tuareg Shield in the west and the Central African Orogenic Belt in the south. The Saharan Metacraton is composed of Neoproterozoic juvenile crust and the relics of pre-Neoproterozoic components reactivated during the Pan-African Orogeny. The Republic of Chad, constrained within the Saharan Metacraton, comprises a Phanerozoic cover overlying Precambrian basement outcroppings in four distinct massifs: the Mayo Kebbi, Tibesti, Ouaddaï, and the Guéra. The Guéra massif is the least studied of the four massifs but it likely preserves structures that were formed during the collision between Congo Craton and Saharan Metacraton. The Guéra Massif is composed of mostly granitic rocks. The granitoids have petrologic features that are consistent with A-type granite, such as micrographic intergrowth of sodic and potassic feldspar, the presence of sodic- and iron-rich amphibole, and iron-rich biotite. Compositionally, the granitic rocks of the Guéra Massif have high silica (SiO2 ≥ 68.9 wt.%) content and are metaluminous to marginally peraluminous. The rocks are classified as ferroan calc-alkalic to alkali-calcic with moderately high to very high Fe* ratios. The first zircon U/Pb geochronology of the silicic rocks from the Guéra Massif yielded three main age groups: 590 Ma, 570 Ma, 560 Ma, while a single gabbro yielded an intermediate age ( 580 Ma). A weakly foliated biotite granite yielded two populations, in which the emplacement age is interpreted to be 590 ± 10 Ma, whereas the younger age (550 ± 11 Ma) is considered to be a deformation age. Furthermore, inherited Meso- to Paleoproterozoic zircons are found in this sample. The geochemical and geochronology data indicate that there is a temporal evolution in the composition of rocks with the old, high Mg# granitoids shifting to young, low Mg# granitoids. This reveals that the A-type granites in the Guéra Massif were probably derived by the repeated melting of a single source region, from an initial fertile source to a less fertile source at distinct intervals. Finally, the oldest inherited zircons indicate that the Guéra Massif is either built upon Paleoproterozoic continental crust or that pre-Neoproterozoic rocks were the source of the silicic Ediacaran rocks.

40Ar* loss in experimentally deformed muscovite and biotite with implications for 40Ar/39Ar geochronology of naturally deformed rocks

USGS Publications Warehouse

Cosca, M.; Stunitz, H.; Bourgeix, A.-L.; Lee, J.P.

2011-01-01

The effects of deformation on radiogenic argon (40Ar*) retentivity in mica are described from high pressure experiments performed on rock samples of peraluminous granite containing euhedral muscovite and biotite. Cylindrical cores, ???15mm in length and 6.25mm in diameter, were drilled from granite collected from the South Armorican Massif in northwestern France, loaded into gold capsules, and weld-sealed in the presence of excess water. The samples were deformed at a pressure of 10kb and a temperature of 600??C over a period 29 of hours within a solid medium assembly in a Griggs-type triaxial hydraulic deformation apparatus. Overall shortening in the experiments was approximately 10%. Transmitted light and secondary and backscattered electron imaging of the deformed granite samples reveals evidence of induced defects and for significant physical grain size reduction by kinking, cracking, and grain segmentation of the micas.Infrared (IR) laser (CO2) heating of individual 1.5-2.5mm diameter grains of muscovite and biotite separated from the undeformed granite yield well-defined 40Ar/39Ar plateau ages of 311??2Ma (2??). Identical experiments on single grains separated from the experimentally deformed granite yield results indicating 40Ar* loss of 0-35% in muscovite and 2-3% 40Ar* loss in biotite. Intragrain in situ ultraviolet (UV) laser ablation 40Ar/39Ar ages (??4-10%, 1??) of deformed muscovites range from 309??13 to 264??7Ma, consistent with 0-16% 40Ar* loss relative to the undeformed muscovite. The in situ UV laser ablation 40Ar/39Ar ages of deformed biotite vary from 301 to 217Ma, consistent with up to 32% 40Ar* loss. No spatial correlation is observed between in situ 40Ar/39Ar age and position within individual grains. Using available argon diffusion data for muscovite the observed 40Ar* loss in the experimentally treated muscovite can be utilized to predict average 40Ar* diffusion dimensions. Maximum 40Ar/39Ar ages obtained by UV laser ablation overlap those of the undeformed muscovite, indicating argon loss of <1% and an average effective grain radius for 40Ar* diffusion ???700??m. The UV laser ablation and IR laser incremental 40Ar/39Ar ages indicating 40Ar* loss of 16% and 35%, respectively, are consistent with an average diffusion radius ???100??m. These results support a hypothesis of grain-scale 40Ar* diffusion distances in undeformed mica and a heterogeneous mechanical reduction in the intragrain effective diffusion length scale for 40Ar* in deformed mica. Reduction in the effective diffusion length scale in naturally deformed samples occurs most probably through production of mesoscopic and submicroscopic defects such as, e.g., stacking faults. A network of interconnected defects, continuously forming and annealing during dynamic deformation likely plays an important role in controlling both 40Ar* retention and intragrain distribution in deformed mica. Intragrain 40Ar/39Ar ages, when combined with estimates of diffusion kinetics and distances, may provide a means of establishing thermochronological histories from individual micas. ?? 2011.

Coordinated U-Pb geochronology, trace element, Ti-in-zircon thermometry and microstructural analysis of Apollo zircons

NASA Astrophysics Data System (ADS)

Crow, Carolyn A.; McKeegan, Kevin D.; Moser, Desmond E.

2017-04-01

We present the results of a coordinated SIMS U-Pb, trace element, Ti-in-zircon thermometry, and microstructural study of 155 lunar zircons separated from Apollo 14, 15, and 17 breccia and soil samples that help resolve discrepancies between the zircon data, the lunar whole rock history and lunar magma ocean crystallization models. The majority of lunar grains are detrital fragments, some nearly 1 mm in length, of large parent crystals suggesting that they crystallized in highly enriched KREEP magmas. The zircon age distributions for all three landing sites exhibit an abundance of ages at ∼4.33 Ga, however they differ in that only Apollo 14 samples have a population of zircons with ages between 4.1 and 3.9 Ga. These younger grains comprise only 10% of all dated lunar zircons and are usually small and highly shocked making them more susceptible to Pb-loss. These observations suggest that the majority of zircons crystallized before 4.1 Ga and that KREEP magmatism had predominantly ceased by this time. We also observed that trace element analyses are easily affected by contributions from inclusions (typically injected impact melt) within SIMS analyses spots. After filtering for these effects, rare-earth element (REE) abundances of pristine zircon are consistent with one pattern characterized by a negative Eu anomaly and no positive Ce anomaly, implying that the zircons formed in a reducing environment. This inference is consistent with crystallization temperatures based on measured Ti concentrations and new estimates of oxide activities which imply temperatures ranging between 958 ± 57 and 1321 ± 100 °C, suggesting that zircon parent magmas were anhydrous. Together, the lunar zircon ages and trace elements are consistent with a ⩽300 My duration of KREEP magmatism under anhydrous, reducing conditions. We also report two granular texture zircons that contain baddeleyite cores, which both yield 207Pb-206Pb ages of 4.33 Ga. These grains are our best constraints on impact ages within our sample population, and suggest at least one large impact is contemporaneous with the most common time of magmatic zircon formation on the Moon's crust visited by the Apollo missions.

Late Permian volcanic dykes in the crystalline basement of the Považský Inovec Mts. (Western Carpathians): U-Th-Pb zircon SHRIMP and monazite chemical dating

NASA Astrophysics Data System (ADS)

Pelech, Ondrej; Vozárová, Anna; Uher, Pavel; Petrík, Igor; Plašienka, Dušan; Šarinová, Katarína; Rodionov, Nikolay

2017-08-01

This paper presents geochronological data for the volcanic dykes located in the northern Považský Inovec Mts. The dykes are up to 5 m thick and tens to hundreds of metres long. They comprise variously inclined and oriented lenses, composed of strongly altered grey-green alkali basalts. Their age was variously interpreted and discussed in the past. Dykes were emplaced into the Tatricum metamorphic rocks, mostly consisting of mica schists and gneisses of the Variscan (early Carboniferous) age. Two different methods, zircon SHRIMP and monazite chemical dating, were applied to determine the age of these dykes. U-Pb SHRIMP dating of magmatic zircons yielded the concordia age of 260.2 ± 1.4 Ma. The Th-U-Pb monazite dating of the same dyke gave the CHIME age of 259 ± 3Ma. Both ages confirm the magmatic crystallization at the boundary of the latest Middle Permian to the Late Permian. Dyke emplacement was coeval with development of the Late Paleozoic sedimentary basin known in the northern Považský Inovec Mts. and could be correlated with other pre-Mesozoic Tethyan regions especially in the Southern Alps.

Evaluation of the rhenium-osmium geochronometer in the Phosphoria petroleum system, Bighorn Basin of Wyoming and Montana, USA

USGS Publications Warehouse

Lillis, Paul G.; Selby, David

2013-01-01

Rhenium-osmium (Re-Os) geochronometry is applied to crude oils derived from the Permian Phosphoria Formation of the Bighorn Basin in Wyoming and Montana to determine whether the radiogenic age reflects the timing of petroleum generation, timing of migration, age of the source rock, or the timing of thermochemical sulfate reduction (TSR). The oils selected for this study are interpreted to be derived from the Meade Peak Phosphatic Shale and Retort Phosphatic Shale Members of the Phosphoria Formation based on oil-oil and oil-source rock correlations utilizing bulk properties, elemental composition, δ13C and δ34S values, and biomarker distributions. The δ34S values of the oils range from -6.2‰ to +5.7‰, with oils heavier than -2‰ interpreted to be indicative of TSR. The Re and Os isotope data of the Phosphoria oils plot in two general trends: (1) the main trend (n = 15 oils) yielding a Triassic age (239 ± 43 Ma) with an initial 187Os/188Os value of 0.85 ± 0.42 and a mean square weighted deviation (MSWD) of 1596, and (2) the Torchlight trend (n = 4 oils) yielding a Miocene age (9.24 ± 0.39 Ma) with an initial 187Os/188Os value of 1.88 ± 0.01 and a MSWD of 0.05. The scatter (high MSWD) in the main-trend regression is due, in part, to TSR in reservoirs along the eastern margin of the basin. Excluding oils that have experienced TSR, the regression is significantly improved, yielding an age of 211 ± 21 Ma with a MSWD of 148. This revised age is consistent with some studies that have proposed Late Triassic as the beginning of Phosphoria oil generation and migration, and does not seem to reflect the source rock age (Permian) or the timing of re-migration (Late Cretaceous to Eocene) associated with the Laramide orogeny. The low precision of the revised regression (±21 Ma) is not unexpected for this oil family given the long duration of generation from a large geographic area of mature Phosphoria source rock, and the possible range in the initial 187Os/188Os values of the Meade Peak and Retort source units. Effects of re-migration may have contributed to the scatter, but thermal cracking and biodegradation likely have had minimal or no effect on the main-trend regression. The four Phosphoria-sourced oils from Torchlight and Lamb fields yield a precise Miocene age Re-Os isochron that may reflect the end of TSR in the reservoir due to cooling below a threshold temperature in the last 10 m.y. from uplift and erosion of overlying rocks. The mechanism for the formation of a Re-Os isotopic relationship in a family of crude oils may involve multiple steps in the petroleum generation process. Bitumen generation from the source rock kerogen may provide a reset of the isotopic chronometer, and incremental expulsion of oil over the duration of the oil window may provide some of the variation seen in 187Re/188Os values from an oil family.

Age- and Activity-Related Differences in the Abundance of Myosin Essential and Regulatory Light Chains in Human Muscle

PubMed Central

Cobley, James N.; Ab. Malik, Zulezwan; Morton, James P.; Close, Graeme L.; Edwards, Ben J.; Burniston, Jatin G.

2016-01-01

Traditional methods for phenotyping skeletal muscle (e.g., immunohistochemistry) are labor-intensive and ill-suited to multixplex analysis, i.e., assays must be performed in a series. Addressing these concerns represents a largely unmet research need but more comprehensive parallel analysis of myofibrillar proteins could advance knowledge regarding age- and activity-dependent changes in human muscle. We report a label-free, semi-automated and time efficient LC-MS proteomic workflow for phenotyping the myofibrillar proteome. Application of this workflow in old and young as well as trained and untrained human skeletal muscle yielded several novel observations that were subsequently verified by multiple reaction monitoring (MRM). We report novel data demonstrating that human ageing is associated with lesser myosin light chain 1 content and greater myosin light chain 3 content, consistent with an age-related reduction in type II muscle fibers. We also disambiguate conflicting data regarding myosin regulatory light chain, revealing that age-related changes in this protein more closely reflect physical activity status than ageing per se. This finding reinforces the need to control for physical activity levels when investigating the natural process of ageing. Taken together, our data confirm and extend knowledge regarding age- and activity-related phenotypes. In addition, the MRM transitions described here provide a methodological platform that can be fine-tuned to suite multiple research needs and thus advance myofibrillar phenotyping. PMID:28248225

Tests of the DRYAD theory of the age-related deficit in memory for context: Not about context, and not about aging

PubMed Central

Benjamin, Aaron S.; Diaz, Michael; Matzen, Laura E.; Johnson, Benjamin

2011-01-01

Older adults exhibit a disproportionate deficit in their ability to recover contextual elements or source information about prior encounters with stimuli. A recent theoretical account, DRYAD (Benjamin, 2010), attributes this selective deficit to a global decrease in memory fidelity with age, moderated by weak representation of contextual information. The predictions of DRYAD are tested here in three experiments. We show that an age-related deficit obtains for whichever aspect of the stimulus subjects’ attention is directed away from during encoding (Experiment 1), suggesting a central role for attention in producing the age-related deficit in context. We also show that an analogous deficit can be elicited within young subjects with a manipulation of study time (Experiment 2), suggesting that any means of reducing memory fidelity yields an interaction of the same form as the age-related effect. Experiment 3 evaluates the critical prediction of DRYAD that endorsement probability in an exclusion task should vary nonmonotonically with memory strength. This prediction was confirmed by assessing the shape of the forgetting function in a continuous exclusion task. The results are consistent with the DRYAD account of aging and memory judgments and do not support the widely held view that aging entails the selective disruption of processes involved in encoding, storing, or retrieving contextual information. PMID:21875219

Tests of the DRYAD theory of the age-related deficit in memory for context: not about context, and not about aging.

PubMed

Benjamin, Aaron S; Diaz, Michael; Matzen, Laura E; Johnson, Benjamin

2012-06-01

Older adults exhibit a disproportionate deficit in their ability to recover contextual elements or source information about prior encounters with stimuli. A recent theoretical account, DRYAD, attributes this selective deficit to a global decrease in memory fidelity with age, moderated by weak representation of contextual information. The predictions of DRYAD are tested here in three experiments. We show that an age-related deficit obtains for whichever aspect of the stimulus subjects' attention is directed away from during encoding (Experiment 1), suggesting a central role for attention in producing the age-related deficit in context. We also show that an analogous deficit can be elicited within young subjects with a manipulation of study time (Experiment 2), suggesting that any means of reducing memory fidelity yields an interaction of the same form as the age-related effect. Experiment 3 evaluates the critical prediction of DRYAD that endorsement probability in an exclusion task should vary nonmonotonically with memory strength. This prediction was confirmed by assessing the shape of the forgetting function in a continuous exclusion task. The results are consistent with the DRYAD account of aging and memory judgments and do not support the widely held view that aging entails the selective disruption of processes involved in encoding, storing, or retrieving contextual information. PsycINFO Database Record (c) 2012 APA, all rights reserved

Detection of the toughest: Pedestrian injury risk as a smooth function of age.

PubMed

Niebuhr, Tobias; Junge, Mirko

2017-07-04

Though it is common to refer to age-specific groups (e.g., children, adults, elderly), smooth trends conditional on age are mainly ignored in the literature. The present study examines the pedestrian injury risk in full-frontal pedestrian-to-passenger car accidents and incorporates age-in addition to collision speed and injury severity-as a plug-in parameter. Recent work introduced a model for pedestrian injury risk functions using explicit formulae with easily interpretable model parameters. This model is expanded by pedestrian age as another model parameter. Using the German In-Depth Accident Study (GIDAS) to obtain age-specific risk proportions, the model parameters are fitted to the raw data and then smoothed by broken-line regression. The approach supplies explicit probabilities for pedestrian injury risk conditional on pedestrian age, collision speed, and injury severity under investigation. All results yield consistency to each other in the sense that risks for more severe injuries are less probable than those for less severe injuries. As a side product, the approach indicates specific ages at which the risk behavior fundamentally changes. These threshold values can be interpreted as the most robust ages for pedestrians. The obtained age-wise risk functions can be aggregated and adapted to any population. The presented approach is formulated in such general terms that in can be directly used for other data sets or additional parameters; for example, the pedestrian's sex. Thus far, no other study using age as a plug-in parameter can be found.

Methods of cutting ponderosa pine in the Southwest - Establishment report: Even-aged yield study, Plot 11

Treesearch

Gilbert H. Schubert

1963-01-01

The objectie of the study is to obtain information on the growth and yield of even-aged stands of different stocking levels. The plot will also serve as the start of a detailed growing stock study for the ponderosa pine region.

Estimating oak growth and yield

Treesearch

Martin E. Dale; Donald E. Hilt

1989-01-01

Yields from upland oak stands vary widely from stand to stand due to differences in age, site quality, species composition, and stand structure. Cutting history and other past disturbances such as grazing or fire also affect yields.

Optimizing Dense Plasma Focus Neutron Yields with Fast Gas Jets

NASA Astrophysics Data System (ADS)

McMahon, Matthew; Kueny, Christopher; Stein, Elizabeth; Link, Anthony; Schmidt, Andrea

2016-10-01

We report a study using the particle-in-cell code LSP to perform fully kinetic simulations modeling dense plasma focus (DPF) devices with high density gas jets on axis. The high density jet models fast gas puffs which allow for more mass on axis while maintaining the optimal pressure for the DPF. As the density of the jet compared to the background fill increases we find the neutron yield increases, as does the variability in the neutron yield. Introducing perturbations in the jet density allow for consistent seeding of the m =0 instability leading to more consistent ion acceleration and higher neutron yields with less variability. Jets with higher on axis density are found to have the greatest yield. The optimal jet configuration is explored. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Kinetics of Static Strain Aging in Polycrystalline NiAl-based Alloys

NASA Technical Reports Server (NTRS)

Weaver, M. L.; Kaufman, M. J.; Noebe, R. D.

1996-01-01

The kinetics of yield point return have been studied in two NiAl-based alloys as a function of aging time at temperatures between 300 and 700 K. The results indicate that the upper yield stress increment, Delta sigma(sub u) (i.e., stress difference between the upper yield point and the final flow stress achieved during prestraining), in conventional purity (CP-NiAl) and in high purity carbon-doped (NiAl-C) material first increased with a t(exp 2/3) relationship before reaching a plateau. This behavior suggests that a Cottrell locking mechanism is the cause for yield points in NiAl. In addition, positive y-axis intercepts were observed in plots of Delta sigma(sub u) versus t(exp 2/3) suggesting the operation of a Snoek mechanism. Analysis according to the Cottrell Bilby model of atmosphere formation around dislocations yields an activation energy for yield point return in the range 70 to 76 kJ/mol which is comparable to the activation energy for diffusion of interstitial impurities in bcc metals. It is, thus, concluded that the kinetics of static strain aging in NiAl are controlled by the locking of dislocations by Cottrell atmospheres of carbon atoms around dislocations.

Cytochrome c oxidase loses catalytic activity and structural integrity during the aging process in Drosophila melanogaster

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Jian-Ching; Rebrin, Igor; Klichko, Vladimir

2010-10-08

Research highlights: {yields} Cytochrome c oxidase loses catalytic activity during the aging process. {yields} Abundance of seven nuclear-encoded subunits of cytochrome c oxidase decreased with age in Drosophila. {yields} Cytochrome c oxidase is specific intra-mitochondrial site of age-related deterioration. -- Abstract: The hypothesis, that structural deterioration of cytochrome c oxidase (CcO) is a causal factor in the age-related decline in mitochondrial respiratory activity and an increase in H{sub 2}O{sub 2} generation, was tested in Drosophila melanogaster. CcO activity and the levels of seven different nuclear DNA-encoded CcO subunits were determined at three different stages of adult life, namely, young-, middle-,more » and old-age. CcO activity declined progressively with age by 33%. Western blot analysis, using antibodies specific to Drosophila CcO subunits IV, Va, Vb, VIb, VIc, VIIc, and VIII, indicated that the abundance these polypeptides decreased, ranging from 11% to 40%, during aging. These and previous results suggest that CcO is a specific intra-mitochondrial site of age-related deterioration, which may have a broad impact on mitochondrial physiology.« less

Survival analysis of cancer risk reduction strategies for BRCA1/2 mutation carriers.

PubMed

Kurian, Allison W; Sigal, Bronislava M; Plevritis, Sylvia K

2010-01-10

Women with BRCA1/2 mutations inherit high risks of breast and ovarian cancer; options to reduce cancer mortality include prophylactic surgery or breast screening, but their efficacy has never been empirically compared. We used decision analysis to simulate risk-reducing strategies in BRCA1/2 mutation carriers and to compare resulting survival probability and causes of death. We developed a Monte Carlo model of breast screening with annual mammography plus magnetic resonance imaging (MRI) from ages 25 to 69 years, prophylactic mastectomy (PM) at various ages, and/or prophylactic oophorectomy (PO) at ages 40 or 50 years in 25-year-old BRCA1/2 mutation carriers. With no intervention, survival probability by age 70 is 53% for BRCA1 and 71% for BRCA2 mutation carriers. The most effective single intervention for BRCA1 mutation carriers is PO at age 40, yielding a 15% absolute survival gain; for BRCA2 mutation carriers, the most effective single intervention is PM, yielding a 7% survival gain if performed at age 40 years. The combination of PM and PO at age 40 improves survival more than any single intervention, yielding 24% survival gain for BRCA1 and 11% for BRCA2 mutation carriers. PM at age 25 instead of age 40 offers minimal incremental benefit (1% to 2%); substituting screening for PM yields a similarly minimal decrement in survival (2% to 3%). Although PM at age 25 plus PO at age 40 years maximizes survival probability, substituting mammography plus MRI screening for PM seems to offer comparable survival. These results may guide women with BRCA1/2 mutations in their choices between prophylactic surgery and breast screening.

[sup 40]Ar/[sup 39]Ar evidence for delayed post-Acadian cooling in the southernmost Connecticut Valley Synclinorium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moecher, D.P.; Cosca, M.A.

1992-01-01

Available Ar-40/Ar-39 data for the Connecticut Valley Synclinorium (CVS) of the New England segment of the Appalachian Orogen indicate rapid post-Acadian cooling. However, new data indicate this pattern does not extend the entire length of the CVS. Ar-40/Ar-39 ages obtained from hornblende and muscovite in The Straits Schist indicate delayed cooling and a more complex post-Acadian thermal history. Data for the Seymour area are consistent with the studies above for the vicinity of the Waterbury Dome. The data farther south indicate one or more of the following: (1) slow (2--3C/Ma) post-Acadian cooling and uplift through the Permian; (2) post-Acadian coolingmore » through Hbl closure in the Mississippian with a subsequent Alleghanian metamorphism that did not exceed 500 C; or (3) post-Acadian cooling with subsequent metamorphism that approached 500 C or involved ductile recrystallization, partly resetting hornblende and totally resetting muscovite south of Derby. Petrologic evidence supporting (2) or (3) consists of widespread but not pervasive greenschist facies retrogression of Hbl + Pl + Sph assemblages in amphibolites to Act + Ep, and Grt + Ky + St assemblages in metapelites to Chl + Bt + Qz. The present data cannot resolve between (2) or (3). However, both are consistent with results of a study in the Bridgeport Synform that yield (1) a U-Pb monazite age of 296 [+-] 2 Ma from the Ansonia Leucogranite, implying the occurrence of an Alleghanian thermal event that promoted monazite growth; and, (2) a U-Pb cooling age of 360 Ma from sphene in the Pumpkin Ground Granodiorite, indicating that Alleghanian events did not exceed ca. 550 C.« less

Spectral decomposition of asteroid Itokawa based on principal component analysis

NASA Astrophysics Data System (ADS)

Koga, Sumire C.; Sugita, Seiji; Kamata, Shunichi; Ishiguro, Masateru; Hiroi, Takahiro; Tatsumi, Eri; Sasaki, Sho

2018-01-01

The heliocentric stratification of asteroid spectral types may hold important information on the early evolution of the Solar System. Asteroid spectral taxonomy is based largely on principal component analysis. However, how the surface properties of asteroids, such as the composition and age, are projected in the principal-component (PC) space is not understood well. We decompose multi-band disk-resolved visible spectra of the Itokawa surface with principal component analysis (PCA) in comparison with main-belt asteroids. The obtained distribution of Itokawa spectra projected in the PC space of main-belt asteroids follows a linear trend linking the Q-type and S-type regions and is consistent with the results of space-weathering experiments on ordinary chondrites and olivine, suggesting that this trend may be a space-weathering-induced spectral evolution track for S-type asteroids. Comparison with space-weathering experiments also yield a short average surface age (< a few million years) for Itokawa, consistent with the cosmic-ray-exposure time of returned samples from Itokawa. The Itokawa PC score distribution exhibits asymmetry along the evolution track, strongly suggesting that space weathering has begun saturated on this young asteroid. The freshest spectrum found on Itokawa exhibits a clear sign for space weathering, indicating again that space weathering occurs very rapidly on this body. We also conducted PCA on Itokawa spectra alone and compared the results with space-weathering experiments. The obtained results indicate that the first principal component of Itokawa surface spectra is consistent with spectral change due to space weathering and that the spatial variation in the degree of space weathering is very large (a factor of three in surface age), which would strongly suggest the presence of strong regional/local resurfacing process(es) on this small asteroid.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leem, Yea-Hyun, E-mail: leemyy@empas.com; Lee, Young-Ik, E-mail: lee0ik@hanmail.net; Son, Hee-Jeong, E-mail: son1106@paran.com

Research highlights: {yields} The progress of neurodegeration are directly linked to the neuroinflammatory response. {yields} We investigate whether exercise improves the neuroinflammation using T{sub g}-NSE/htau23 mice. {yields} This provides insights that exercise may beneficial effects on the neuroinflammatory disorders. -- Abstract: The objective of the present study was to investigate whether chronic endurance exercise attenuates the neuroinflammation in the brain of mice with NSE/htau23. In this study, the tau-transgenic (Tg) mouse, Tg-NSE/htau23, which over expresses human Tau23 in its brain, was subjected to chronic exercise for 3 months, from 16 months of age. The brains of Tg mice exhibited increasedmore » immunoreactivity and active morphological changes in GFAP (astrocyte marker) and MAC-1 (microglia marker) expression in an age-dependent manner. To identify the effects of chronic exercise on gliosis, the exercised Tg mice groups were treadmill run at a speed of 12 m/min (intermediate exercise group) or 19 m/min (high exercise group) for 1 h/day and 5 days/week during the 3 month period. The neuroinflammatory response characterized by activated astroglia and microglia was significantly repressed in the exercised Tg mice in an exercise intensity-dependent manner. In parallel, chronic exercise in Tg mice reduced the increased expression of TNF-{alpha}, IL-6, IL-1{beta}, COX-2, and iNOS. Consistently with these changes, the levels of phospho-p38 and phospho-ERK were markedly downregulated in the brain of Tg mice after exercise. In addition, nuclear NF-{kappa}B activity was profoundly reduced after chronic exercise in an exercise intensity-dependent manner. These findings suggest that chronic endurance exercise may alleviate neuroinflammation in the Tau pathology of Alzheimer's disease.« less

Evidence for a high slip rate of the Calico fault in the Eastern California Shear Zone

NASA Astrophysics Data System (ADS)

Xie, S.; Wetmore, P. H.; Owen, L. A.; Gallant, E.; Dixon, T. H.

2016-12-01

Fault slip rates provide important constraint on seismic hazard assessments. Geologic and geodetic estimates of slip rates across the Eastern California Shear Zone (ECSZ) reveal a discrepancy between the two data sets. Most studies attempting to reconcile the discrepancy have focused on off-fault deformation and the technique limitation of short-term geodetic measurements, while there is less concern about the relatively small number of cited geologic slip rates. The Calico fault is central fault in the Mojave Desert portion of the ECSZ, where published geologic slip rates are between 1 and 2 mm/yr. We determine new geologic slip rates of the Calico fault by dating two offset alluvial fans near the town of Newberry Springs, California. Correlation of the offset fans was based on geomorphic and soil development characteristics. Offset magnitudes are based on high-resolution topography and orthoimagery, and by cropping and matching the alluvial fans along the fault trace. Surface displacements of the two offset fans are 80 m and 1120 m. Surface exposure ages of alluvial fan samples are dated using the production of 10Be terrestrial cosmogenic nuclide (TCN). The fan with an 80 m offset produced an age of 40 ka, yielding a slip rate of 2 mm/yr, consistent with previous studies. The fan with displacement of 1120 m produced an age of 290 ka, yielding a slip rate of 4 mm/yr, indicating that the Calico fault likely had a much higher slip rate early and has decreased more recently.

Do Macrophylogenies Yield Stable Macroevolutionary Inferences? An Example from Squamate Reptiles.

PubMed

Title, Pascal O; Rabosky, Daniel L

2017-09-01

Advances in the generation, retrieval, and analysis of phylogenetic data have enabled researchers to create phylogenies that contain many thousands of taxa. These "macrophylogenies"-large trees that typically derive from megaphylogeny, supermatrix, or supertree approaches-provide researchers with an unprecedented ability to conduct evolutionary analyses across broad phylogenetic scales. Many studies have now used these phylogenies to explore the dynamics of speciation, extinction, and phenotypic evolution across large swaths of the tree of life. These trees are characterized by substantial phylogenetic uncertainty on multiple levels, and the stability of macroevolutionary inferences from these data sets has not been rigorously explored. As a case study, we tested whether five recently published phylogenies for squamate reptiles-each consisting of more than 4000 species-yield congruent inferences about the processes that underlie variation in species richness across replicate evolutionary radiations of Australian snakes and lizards. We find discordance across the five focal phylogenies with respect to clade age and several diversification rate metrics, and in the effects of clade age on species richness. We also find that crown clade ages reported in the literature on these Australian groups are in conflict with all of the large phylogenies examined. Macrophylogenies offer an unprecedented opportunity to address evolutionary and ecological questions at broad phylogenetic scales, but accurately representing the uncertainty that is inherent to such analyses remains a critical challenge to our field. [Australia; macroevolution; macrophylogeny; squamates; time calibration.]. © The Author(s) 2016. Published by Oxford University Press, on behalf of the Society of Systematic Biologists. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Origin Of Black Shale (Marl) Formation Aided By Continuous Volcanism For 10Ma Including Oceanic Anoxic Event, OAE2 (93-93.5 Ma) In The Eagle Ford Formation In South Texas

NASA Astrophysics Data System (ADS)

Chakrabarty, P.; Basu, A. R.

2017-12-01

We report LA-ICPMS U-Pb ages and Hf isotopes of zircons, petrography, major and trace elements and X-ray diffraction (XRD) analyses of whole rock black shales(marls) from volcanic subsurface as well as surface exposure ash beds of the Eagle Ford and Boquillas Formations in South Texas. Zircons from the middle part of the 300ft long Eagle Ford cores yield ages of 93.2±1.66 Ma, 94.13±1.25 Ma and 93.7±1.9 Ma. These ages are consistent with the Cenomanian-Turonian (C-T) age of deposition in three contiguous cores with spatial separation of 140 miles. An approximate 10Ma duration of deposition of volcanic ash and marl, at a rate of 28ft/Ma for the Eagle Ford is suggested from the 85.76 to 95.5 Ma ages. These ages are from the Eagle Ford ash beds, below the Austin Chalk and above the Buda Limestone and cover the Oceanic Anoxic Event 2 at the C-T boundary. Zircons from 7 ash beds in the surface exposures of the Boquillas Formation near Del Rio, yield ages between 84.63 Ma - 90.91 Ma, implying younger than C-T boundary ages for these samples. The mineralogy, major and trace elements of the ash beds suggest their source from nearby arc-derived calc-alkaline volcanism. The ɛHf(T) of the analyzed ash bed zircons yield values between 0 - +8 averaging at +3.5, clearly indicating a mantle component in the host magmas of the zircons. This initial range of ɛHf(T) is similar to arc-volcanism signatures such as the Quaternary andesitic volcanism in Central Mexico. Petrographic analyses of marls away from the visible tuff layer contain phenocrysts of biotite, alkali feldspar and andesitic rock fragments. The whole rock marl with high concentration of some transition metals (V, Zn, Ni, Pb, Mo) and relatively higher MgO and TiO2 contents indicate contemporaneous arc volcanic activity at the time of marl deposition. XRD of subsurface Eagle Ford bulk marl samples from different depths in 4 cores, show volcanogenic clays, such as montmorillonite, vermiculite, dickite and halloysite 10Å, ranging from 2 to 12% in modal abundance. This observation indicates continuous volcanism throughout the Eagle Ford deposition. This volcanism during the Eagle Ford deposition of volcanic silicic sediments and carbonates was part of the global continental arc flare-ups in the Cretaceous, responsible for greenhouse conditions and subsequent anoxia during marl deposition.

Observations and controls on the occurrence of inherited zircon in Concord-type granitoids, New Hampshire

USGS Publications Warehouse

Harrison, T.M.; Aleinikoff, J.N.; Compston, W.

1987-01-01

U-Pb analyses of zircons separated from two Concord-type plutons near Sunapee and Dixville Notch, New Hampshire, reveal differences in the pattern and magnitude of zircon inheritance which are related to differences in melt chemistry. The Sunapee pluton contains only slightly more Zr than required to saturate the melt at the peak temperature of 700 ?? 30??C. Traces of inherited zircon in this separate are inferred to be present as small, largely resorbed grains. In contrast, the Long Mountain pluton, near Dixville Notch, contains about 240% more Zr than required to saturate the melt. Thus, more than half of the Zr existed as stable, inherited zircon crystals during the partial fusion event, consistent with the observation of substantial inheritance in all grain size fractions. Ion probe intra-grain analyses of zircon from the Long Mountain pluton indicate a complex pattern of inheritance with contributions from at least two Proterozoic terrenes and caution against simple interpretations of upper and lower intercepts of chords containing an inherited component. Ion probe analyses of zircons from the Sunapee pluton reveal clear evidence of U loss which results in incorrect apparent conventional U-Pb ages. Ages of crystallization for the Long Mountain and Sunapee pluton are ~350 and 354 ?? 5 Ma, respectively. A Sm/Nd measurement for the Long Mountain pluton yields a depleted mantle model age of 1.5 Ga, consistent with the observed inheritance pattern. In contrast, a Sm/Nd model age for the Sunapee pluton is improbably old due to minor monazite fractionation. ?? 1987.

A novel approach to in-situ rutile petrochronology

NASA Astrophysics Data System (ADS)

Kooijman, Ellen; Smit, Matthijs; Kylander-Clark, Andrew

2017-04-01

Rutile petrochronology has become an increasingly important tool for deciphering the timing and conditions of petrological processes. Rutile provides a reliable single-mineral thermometer, capable of retaining temperature information during high and ultra-high temperature metamorphism. Its HFSE contents can be used to investigate the geochemical environment in which rutile crystallized. Most importantly, rutile strongly fractionates U/Pb and enables U-Pb thermochronology in the intermediate temperature range. Here we present a novel approach to using U-Pb thermochronology of rutile by exploring the use of Pb as a diffusive species in kinetics-based thermometry. We performed high spatial and analytical resolution micro-analysis of rutile by laser ablation multi-collector ICPMS to constrain Pb diffusion profiles in rutile from high-grade metamorphic rocks of the Western Gneiss Complex (WGC), Norway. The age and thermometric results from this analysis are used to constrain a full thermal history from single grains. Millimeter-sized single crystals of rutile from a rutile-rich phlogopitite vein in eclogite were mounted and polished to expose their geometric cores. The grains were analyzed in transects using rectangular spots (c. 15x45 μm). This ensures ablation of a significant volume while maintaining the required radial spatial resolution. The transects yielded well-defined Pb diffusion profiles, with U-Pb ages ranging from c. 415 Ma in the cores to c. 380 Ma in the outermost rims (±2%, 2σ on individual spots). Diffusion zoning length was used with well-established Pb diffusion parameters [1] to determine peak temperature conditions following the approach of [2]. The result, c. 810 ± 25 ˚ C, is consistent with 800 ± 25 ˚ C and c. 780 ˚ C estimated for the same sample using conventional and Zr-in-rutile thermometry, respectively. The cooling history that is reconstructed through age zoning analysis and diffusion modeling shows remarkable consistency with that established for the WGC through decades of 40Ar/39Ar dating. The data presented here demonstrate that in-situ rutile U-Pb analysis yields reliable and precise temperature and age information that can be combined to resolve full thermal histories from single crystals. This novel approach to the toolbox of rutile petrochronology has great potential for research into the tectonics and dynamics of the lithosphere. References [1] Cherniak (2000) Contrib. Mineral. Petrol. 139. 198-207. [2] Smit et al. (2013) J. Metamorph. Geol. 31. 339-358.

Influence of Pre- and Postharvest Summer Pruning on the Growth, Yield, Fruit Quality, and Carbohydrate Content of Early Season Peach Cultivars

PubMed Central

Ikinci, Ali

2014-01-01

Winter and summer pruning are widely applied processes in all fruit trees, including in peach orchard management. This study was conducted to determine the effects of summer prunings (SP), as compared to winter pruning (WP), on shoot length, shoot diameter, trunk cross sectional area (TCSA) increment, fruit yield, fruit quality, and carbohydrate content of two early ripening peach cultivars (“Early Red” and “Maycrest”) of six years of age, grown in semiarid climate conditions, in 2008 to 2010. The trees were grafted on GF 677 rootstocks, trained with a central leader system, and spaced 5 × 5 m apart. The SP carried out after harvesting in July and August decreased the shoot length significantly; however, it increased its diameter. Compared to 2009, this effect was more marked in year 2010. In general, control and winter pruned trees of both cultivars had the highest TCSA increment and yield efficiency. The SP increased the average fruit weight and soluble solids contents (SSC) more than both control and WP. The titratable acidity showed no consistent response to pruning time. The carbohydrate accumulation in shoot was higher in WP and in control than in SP trees. SP significantly affected carbohydrate accumulation; postharvest pruning showed higher carbohydrate content than preharvest pruning. PMID:24737954

Early Carboniferous (˜357 Ma) crust beneath northern Arabia: Tales from Tell Thannoun (southern Syria)

NASA Astrophysics Data System (ADS)

Stern, Robert J.; Ren, Minghua; Ali, Kamal; Förster, Hans-Jürgen; Al Safarjalani, Abdulrahman; Nasir, Sobhi; Whitehouse, Martin J.; Leybourne, Matthew I.; Romer, Rolf L.

2014-05-01

Continental crust beneath northern Arabia is deeply buried and poorly known. To advance our knowledge of this crust, we studied 8 xenoliths brought to the surface by Neogene eruptions of Tell Thannoun, S. Syria. The xenolith suite consists of two peridotites, one pyroxenite, four mafic granulites, and one charnockite. The four mafic granulites and charnockite are probably samples of the lower crust, and two mafic granulites gave 2-pyroxene equilibration temperatures of 780-800 °C, which we take to reflect temperatures at the time of formation. Peridotite and pyroxenite gave significantly higher temperatures of ∼900 °C, consistent with derivation from the underlying lithospheric mantle. Fe-rich peridotite yielded T∼800 °C, perhaps representing a cumulate layer in the crust. Three samples spanning the lithologic range of the suite (pyroxenite, mafic granulite, and charnockite) yielded indistinguishable concordant U-Pb zircon ages of ∼357 Ma, interpreted to approximate when these magmas crystallized. These igneous rocks are mostly juvenile additions from the mantle, as indicated by low initial 87Sr/86Sr (0.70312 to 0.70510) and strongly positive initial εNd(357 Ma) (+4 to +9.5). Nd model ages range from 0.55 to 0.71 Ga. We were unable to unequivocally infer a tectonic setting where these melts formed: convergent margin, rift, or hotspot. These xenoliths differ from those of Jordan and Saudi Arabia to the south in four principal ways: 1) age, being least 200 Ma younger than the presumed Neoproterozoic (533-1000 Ma) crust beneath Jordan and Saudi Arabia; 2) the presence of charnockite; 3) abundance of Fe-rich mafic and ultramafic lithologies; and 4) the presence of sapphirine. Our studies indicate that northern Arabian plate lithosphere contains a significant proportion of juvenile Late Paleozoic crust, the extent of which remains to be elucidated. This discovery helps explain fission track resetting documented for rocks from Israel and provides insights into the nature of Late Paleozoic (Hercynian) deformation that affected Arabia near the Persian Gulf.

Serrated yielding in Al-Li alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, S.; McShane, H.B.

1993-05-01

Serrated yielding (SY) during tensile testing has been observed in Al-Li alloys, both in the binary and the commercial quaternary alloys, in single crystal as well as polycrystalline materials. Serrated yielding is commonly explained by a dynamic strain aging (DSA) model developed by McCormick and van den Beukel. All the solute elements present in Al-Li alloys, viz., Mg, Cu and Li are known to give DSA and SY. Several researchers believe the DSA to be the cause of SY and they attribute the disappearance of SY simply to the removal of solute from the matrix with aging. However, this argumentmore » has serious flaws. The present paper examines this aspect critically. The authors concluded that Al-Li alloys the disappearance of serrated yielding at a certain stage of aging is not due to removal of the solute from the matrix but due to the change in the nature of the metastable [delta][prime] precipitates - from fine coherent shearable precipitates to larger noncoherent nonshearable precipitates - which prevents the formation of the deformation bands. The serrated yielding reappears with extensive over aging due to the dissolution of these precipitates in favor of the equilibrium precipitates. The equilibrium precipitates, being widely spaced, are ineffective in preventing the formation of deformation bands.« less

The Exhumation of the Central Lhasa, Tibet: Evidence from the Low-temperature Thermochronology

NASA Astrophysics Data System (ADS)

Sun, G.; Xiumian, H.; Sinclair, H. D.; Stuart, F. M.

2017-12-01

The modern Tibetan Plateau has an average elevation of 4500 m above the sea level. But its early growth history still remains debate, despite its significance to the global climate system. In common, the early growth of the Tibetan Plateau has been attributed to the India-Asia collision in the early Paleocene. However, the structural reconstruction, Late Cretaceous sedimentation, and petrology studies, imply there would be a paleo-plateau or the high-elevation gain in the Lhasa terrane prior to the India-Asia collision. In order to examine this model, the zircon/apatite U-Th-He (ZHe and AHe) and apatite fission track (AFT) are employed to the mid-Cretaceous granites in Coqen area, central Lhasa. Eight samples from the plateau surface yield ZHe ages ranging from 88 to 54 Ma, while the AHe ages ranging from 70 to 45 Ma. Five samples from the above have been conducted the AFT analysis and yielded AFT ages ranging between 73 and 62 Ma, showing the similar age ranges with the corresponding AHe ages. Single-sample inverse thermal kinetic modeling reveal that these intrusive rocks have undergone the rapid cooling history since 85 Ma, after when, the relatively slow cooling process has been established at 45 Ma. Inverse thermal-kinetic modeling of these data, recorded in the context of the Late Cretaceous rapid cooling history, is best interpreted by the early plateau growth in the central Lhasa. In consideration of the substantial crustal thickening and shortening in the Lhasa terrane during the Cretaceous, this Late Cretaceous-Early Paleogene rapid cooling history reveal that the exhumation of the central Lhasa has initiated before the India-Asia collision. This scenario is consistent with a 30 Ma ( 90-60 Ma) sedimentation hiatus since the Late Cretaceous terrestrial conglomerate deposition in the central Lhasa terrane.

Collaborative simulations and experiments for a novel yield model of coal devolatilization in oxy-coal combustion conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iavarone, Salvatore; Smith, Sean T.; Smith, Philip J.

Oxy-coal combustion is an emerging low-cost “clean coal” technology for emissions reduction and Carbon Capture and Sequestration (CCS). The use of Computational Fluid Dynamics (CFD) tools is crucial for the development of cost-effective oxy-fuel technologies and the minimization of environmental concerns at industrial scale. The coupling of detailed chemistry models and CFD simulations is still challenging, especially for large-scale plants, because of the high computational efforts required. The development of scale-bridging models is therefore necessary, to find a good compromise between computational efforts and the physical-chemical modeling precision. This paper presents a procedure for scale-bridging modeling of coal devolatilization, inmore » the presence of experimental error, that puts emphasis on the thermodynamic aspect of devolatilization, namely the final volatile yield of coal, rather than kinetics. The procedure consists of an engineering approach based on dataset consistency and Bayesian methodology including Gaussian-Process Regression (GPR). Experimental data from devolatilization tests carried out in an oxy-coal entrained flow reactor were considered and CFD simulations of the reactor were performed. Jointly evaluating experiments and simulations, a novel yield model was validated against the data via consistency analysis. In parallel, a Gaussian-Process Regression was performed, to improve the understanding of the uncertainty associated to the devolatilization, based on the experimental measurements. Potential model forms that could predict yield during devolatilization were obtained. The set of model forms obtained via GPR includes the yield model that was proven to be consistent with the data. Finally, the overall procedure has resulted in a novel yield model for coal devolatilization and in a valuable evaluation of uncertainty in the data, in the model form, and in the model parameters.« less

Collaborative simulations and experiments for a novel yield model of coal devolatilization in oxy-coal combustion conditions

DOE PAGES

Iavarone, Salvatore; Smith, Sean T.; Smith, Philip J.; ...

2017-06-03

Oxy-coal combustion is an emerging low-cost “clean coal” technology for emissions reduction and Carbon Capture and Sequestration (CCS). The use of Computational Fluid Dynamics (CFD) tools is crucial for the development of cost-effective oxy-fuel technologies and the minimization of environmental concerns at industrial scale. The coupling of detailed chemistry models and CFD simulations is still challenging, especially for large-scale plants, because of the high computational efforts required. The development of scale-bridging models is therefore necessary, to find a good compromise between computational efforts and the physical-chemical modeling precision. This paper presents a procedure for scale-bridging modeling of coal devolatilization, inmore » the presence of experimental error, that puts emphasis on the thermodynamic aspect of devolatilization, namely the final volatile yield of coal, rather than kinetics. The procedure consists of an engineering approach based on dataset consistency and Bayesian methodology including Gaussian-Process Regression (GPR). Experimental data from devolatilization tests carried out in an oxy-coal entrained flow reactor were considered and CFD simulations of the reactor were performed. Jointly evaluating experiments and simulations, a novel yield model was validated against the data via consistency analysis. In parallel, a Gaussian-Process Regression was performed, to improve the understanding of the uncertainty associated to the devolatilization, based on the experimental measurements. Potential model forms that could predict yield during devolatilization were obtained. The set of model forms obtained via GPR includes the yield model that was proven to be consistent with the data. Finally, the overall procedure has resulted in a novel yield model for coal devolatilization and in a valuable evaluation of uncertainty in the data, in the model form, and in the model parameters.« less

Meteorological fluctuations define long-term crop yield patterns in conventional and organic production systems

USDA-ARS?s Scientific Manuscript database

Periodic variability in meteorological patterns presents significant challenges to crop production consistency and yield stability. Meteorological influences on corn and soybean grain yields were analyzed over an 18-year period at a long-term experiment in Beltsville, Maryland, U.S.A., comparing c...

The Age of Upper Scorpius from Eclipsing Binaries

NASA Astrophysics Data System (ADS)

David, Trevor; Hillenbrand, Lynne

2018-01-01

The Upper Scorpius OB association is the nearest region of recent massive star formation and thus an important benchmark for investigations concerning astrophysical timescales. Classical estimates of the association age based on the kinematics of high-mass members and a Hertzsprung-Russell (H-R) diagram of the full stellar population established an age of 5 Myr. However, recent analyses based on the H-R diagram for intermediate- and high-mass members suggest an older age of 11 Myr. Importantly, the H-R diagram ages of stars in Upper Scorpius (and other clusters of a similar age) are mass-dependent, such that low-mass members appear younger than their high-mass counterparts. Here we report an age that is self-consistent in the mass range of 0.3–5 M⊙, and based on the fundamentally-determined masses and radii of eclipsing binaries (EBs). We present nine EBs in Upper Scorpius, four of which are newly reported here and all of which were discovered from K2 photometry. Joint fitting of the eclipse photometry and radial velocities from newly acquired Keck-I/HIRES spectra yields precise masses and radii for those systems that are spectroscopically double-lined. We identify one of the EB components as a slowly pulsating B-star. We use these EBs to develop an empirical mass-radius relation for pre-main-sequence stars, and to evaluate the predictions of widely-used stellar evolutionary models. Our results are consistent with previous studies that indicate most models underestimate the masses of low-mass stars by tens of percent based on H-R diagram analyses. Models including the effects of magnetic fields produce better agreement between the observed bulk and radiative parameters of these young, low-mass stars. From the orbital elements and photometrically inferred rotation periods, we consider the dynamical states of several binaries and compare with expectations from tidal dissipation theories.

Asteroid age distributions determined by space weathering and collisional evolution models

NASA Astrophysics Data System (ADS)

Willman, Mark; Jedicke, Robert

2011-01-01

We provide evidence of consistency between the dynamical evolution of main belt asteroids and their color evolution due to space weathering. The dynamical age of an asteroid's surface (Bottke, W.F., Durda, D.D., Nesvorný, D., Jedicke, R., Morbidelli, A., Vokrouhlický, D., Levison, H. [2005]. Icarus 175 (1), 111-140; Nesvorný, D., Jedicke, R., Whiteley, R.J., Ivezić, Ž. [2005]. Icarus 173, 132-152) is the time since its last catastrophic disruption event which is a function of the object's diameter. The age of an S-complex asteroid's surface may also be determined from its color using a space weathering model (e.g. Willman, M., Jedicke, R., Moskovitz, N., Nesvorný, D., Vokrouhlický, D., Mothé-Diniz, T. [2010]. Icarus 208, 758-772; Jedicke, R., Nesvorný, D., Whiteley, R.J., Ivezić, Ž., Jurić, M. [2004]. Nature 429, 275-277; Willman, M., Jedicke, R., Nesvorny, D., Moskovitz, N., Ivezić, Ž., Fevig, R. [2008]. Icarus 195, 663-673. We used a sample of 95 S-complex asteroids from SMASS and obtained their absolute magnitudes and u, g, r, i, z filter magnitudes from SDSS. The absolute magnitudes yield a size-derived age distribution. The u, g, r, i, z filter magnitudes lead to the principal component color which yields a color-derived age distribution by inverting our color-age relationship, an enhanced version of the 'dual τ' space weathering model of Willman et al. (2010). We fit the size-age distribution to the enhanced dual τ model and found characteristic weathering and gardening times of τw = 2050 ± 80 Myr and τg=4400-500+700Myr respectively. The fit also suggests an initial principal component color of -0.05 ± 0.01 for fresh asteroid surface with a maximum possible change of the probable color due to weathering of Δ PC = 1.34 ± 0.04. Our predicted color of fresh asteroid surface matches the color of fresh ordinary chondritic surface of PC1 = 0.17 ± 0.39.

Comparison of Radiocarbon Ages of Sediments, Plants, and Shells From Coastal Lakes in North Florida

NASA Astrophysics Data System (ADS)

Wang, Y.; Das, O.; Liu, J.; Xu, X.; Roy, R.; Donoghue, J. F.; Means, G. H.

2017-12-01

Coastal lakes sediments are valuable archives of paleo-hurricanes and environmental changes during the late Quaternary provided that they can be accurately dated. Here, we report new radiocarbon (14C) dates derived from various organic and inorganic substrates, including bulk sediment organic matter, plants, shells, particulate organic matter (POM) and dissolved organic matter (DOM), from three coastal lakes in Florida, and compare these ages to evaluate the "reservoir effect" on 14C dating of both organic and inorganic carbon in these lakes. Bulk sediment organic matter yielded consistently older 14C ages than contemporaneous plants and shell fragments, indicating significant radiocarbon deficiencies in sedimentary organic matter in these coastal lakes, caused by influx of old organic carbon from terrestrial sources (such as soils and ancient peat deposits) in the watershed. Several reversals are observed in the 14C ages of bulk sediment organic matter in sediment cores from these lakes, indicating that input of aged organic matter from terrestrial sources into these lakes can vary considerably over time. DOM and POM samples collected at different times also yielded variable 14C signatures, further confirming the temporal variability in the contribution of old organic carbon from terrestrial sources to the lakes. The 14C age discrepancy between bulk sediment organic matter and co-occurring plant fragments or shells varies from less than one hundred years to nearly three thousand years in sediment cores examined in this study. The results show that 14C ages obtained from bulk sediment organic matter in these coastal lakes are unreliable. Analyses of both modern and fossil shells from one of the lakes suggest that the 14C reservoir effect on inorganic carbon in the lake is small and thus freshwater shells (if preserved in the sediment cores) may serve as a good substrate for 14C dating in the absence of plant fragments. However, unidentifiable shell fragments, especially those associated with sand pockets (or sand layers), in coastal lake sediment cores are not suitable for 14C dating as they are likely of marine origin and affected by significant marine 14C reservoir effect.

Metasomatic processes in the orthogneiss-hosted Archaean peridotites of the Fiskefjord region, SW Greenland

NASA Astrophysics Data System (ADS)

Szilas, K.; Cruz, M. F.; Grove, M.; Morishita, T.; Pearson, D. G.

2016-12-01

Field observations and preliminary geochemical data are presented for large (>500x1000m) peridotite enclaves from the Fiskefjord region of SW Greenland. These ultramafic complexes are dominated by dunite, amphibole-harzburgite, lesser amounts of norite and horizons of stratiform chromitite and are therefore interpreted as cumulate rocks[1]. The ultramafic enclaves are hosted by intrusive tonalitic orthogneiss, which provide U-Pb zircon minimum age constraints of ca. 2980 Ma, whereas preliminary Re-Os isotope data on the dunite and chromitite yield TRD ages of ca. 3300 Ma[2]. Dunite has highly forsteritic olivine compositions with Mg# mostly around 92 to 93, which is uncorrelated with the bulk-rock mg# or modal chromite contents. This indicates that the primary olivine records equilibration with a highly magnesian parental magma, which may have been responsible for the strong depletion of the SCLM in this region. Amphibole and phlogopite is mostly associated with granitoid sheets or infiltrating veins in the dunite and appear to replace chromite. Argon dating (40Ar/39Ar) of the phlogopite yields ages ranging from ca. 3400 Ma to ca. 1750 Ma, with most ages clustering around 3000 Ma. This is consistent with formation of the phlogopite and amphibole by metasomatic processes involving reaction between granitoid-derived siliceous fluids and the ultramafic rocks. The older 40Ar/39Ar age plateaus most plausibly represent excess Ar, potentially inherited from the nearby Itsaq Gneiss Complex (3900 to 3600 Ga) based on its proximity. The youngest 40Ar/39Ar age plateaus on the other hand may potentially signify the closure-age for this system, which could have important implications for determining the exhumation history of the North Atlantic craton. References [1] Szilas, K., Kelemen, P. B., & Bernstein, S. (2015). Peridotite enclaves hosted by Mesoarchaean TTG-suite orthogneisses in the Fiskefjord region of southern West Greenland. GeoResJ, 7, 22-34. [2] Szilas, K., van Hinsberg, V. J., McDonald, I., Morishita, T., Pearson, D. G. (2016). Highly depleted peridotites within Mesoarchaean orthogneiss at the Seqi Olivine Mine, SW Greenland - Potential implications for the formation of cratonic keels. Goldschmidt Conference Abstract #3009, Yokohama.

The restricted gemuk group: A triassic to lower cretaceous succession in southwestern alaska

USGS Publications Warehouse

Miller, M.L.; Bradley, D.C.; Bundtzen, T.K.; Blodgett, R.B.; Pessagno, E.A.; Tucker, R.D.; Harris, A.G.

2007-01-01

New data from an Upper Triassic to Lower Cretaceous deep marine succession-the herein reinstated and restricted Gemuk Group-provide a vital piece of the puzzle for unraveling southwestern Alaska's tectonic history. First defined by Cady et al. in 1955, the Gemuk Group soon became a regional catchall unit that ended up as part of at least four different terranes. In this paper we provide the first new data in nearly half a century from the Gemuk Group in the original type area in Taylor Mountains quadrangle and from contiguous rocks to the north in Sleetmute quadrangle. Discontinuous exposure, hints of complex structure, the reconnaissance level of our mapping, and spotty age constraints together permit definition of only a rough stratigraphy. The restricted Gemuk Group is at least 2250 m thick, and could easily be at least twice as thick. The age range of the restricted Gemuk Group is tightened on the basis of ten radiolarian ages, two new bivalve ages, one conodont age, two U-Pb zircon ages on tuff, and U-Pb ages of 110 detrital zircons from two sandstones. The Triassic part of the restricted Gemuk Group, which consists of intermediate pillow lavas interbedded with siltstone, chert, and rare limestone, produced radiolarians, bivalves, and conodonts of Carnian and Norian ages. The Jurassic part appears to be mostly siltstone and chert, and yielded radiolarians of Hettangian- Sinemurian, Pliensbachian-Toarcian, and Oxfordian ages. Two tuffs near the Jurassic-Cretaceous boundary record nearby arc volcanism: one at 146 Ma is interbedded with red and green siltstone, and a second at ca. 137 Ma is interbedded with graywacke turbidites. Graywacke appears to be the dominant rock type in the LowerCretaceous part of the restricted Gemuk Group. Detrital zircon analyses were performed on two sandstone samples using SHRIMP. One sandstone yielded a dominant age cluster of 133-180 Ma; the oldest grain is only 316 Ma. The second sample is dominated by zircons of 130-154 Ma; the oldest grain is 292 Ma. The youngest zircons are probably not much older than the sandstone itself. Point counts of restricted Gemuk Group sandstones yield average ratios of 24/29/47 for Q/F/L, 15/83/2 for Ls/Lv/Lm, and 41/48/11 for Qm/P/K. In the field, sandstones of the restricted Gemuk Group are not easily distinguished from sandstones of the overlying Upper Cretaceous turbidite-dominated Kuskokwim Group. Petrographically, however, the restricted Gemuk Group has modal K-feldspar, whereas the Kuskokwim Group generally does not (average Qm/P/K of 64/36/0). Some K-feldspar-bearing graywacke that was previously mapped as Kuskokwim Group (Cady et al., 1955) is here reassigned to the restricted Gemuk Group. Major- and trace element geochemistry of shales from the restricted Gemuk Group and the Kuskokwim Group show distinct differences. The chemical index of alteration (CIA) is distinctly higher forshales of the Kuskokwim Group than for those of the restricted Gemuk Group, suggesting more intense weathering during deposition of the Kuskokwim Group. The restricted Gemuk Group represents an estimated 90-100 m.y. of deep-water sedimentation, first accompanied by submarine volcanism and later by nearby explosive arc activity. Two hypotheses are presented for the tectonic setting. One model that needs additional testing is that the restricted Gemuk Group consists of imbricated oceanic plate stratigraphy. Based on available information, our preferred model is that it was deposited in a back-arc, intra-arc, or forearc basin that was subsequently deformed. The terrane affinity of the restricted Gemuk Group is uncertain. The rocks of this area were formerly assigned to the Hagemeister subterrane of the Togiak terrane-a Late Triassic to Early Cretaceous arc-but our data show this to be a poor match. None of the other possibilities (e.g., Nukluk and Tikchik subterranes of the Goodnews terrane) is viable; hence, the terrane subdivision and distribution in southwestern Alaska may need

Search For Star Cluster Age Gradients Across Spiral Arms of Three LEGUS Disk Galaxies

NASA Astrophysics Data System (ADS)

Shabani, F.; Grebel, E. K.; Pasquali, A.; D'Onghia, E.; Gallagher, J. S.; Adamo, A.; Messa, M.; Elmegreen, B. G.; Dobbs, C.; Gouliermis, D. A.; Calzetti, D.; Grasha, K.; Elmegreen, D. M.; Cignoni, M.; Dale, D. A.; Aloisi, A.; Smith, L. J.; Tosi, M.; Thilker, D. A.; Lee, J. C.; Sabbi, E.; Kim, H.; Pellerin, A.

2018-05-01

One of the main theories for explaining the formation of spiral arms in galaxies is the stationary density wave theory. This theory predicts the existence of an age gradient across the arms. We use the stellar cluster catalogues of the galaxies NGC 1566, M51a, and NGC 628 from the Legacy Extragalactic UV Survey (LEGUS) program. In order to test for the possible existence of an age sequence across the spiral arms, we quantified the azimuthal offset between star clusters of different ages in our target galaxies. We found that NGC 1566, a grand-design spiral galaxy with bisymmetric arms and a strong bar, shows a significant age gradient across the spiral arms that appears to be consistent with the prediction of the stationary density wave theory. In contrast, M51a with its two well-defined spiral arms and a weaker bar does not show an age gradient across the arms. In addition, a comparison with non-LEGUS star cluster catalogues for M51a yields similar results. We believe that the spiral structure of M51a is not the result of a stationary density wave with a fixed pattern speed. Instead, tidal interactions could be the dominant mechanism for the formation of spiral arms. We also found no offset in the azimuthal distribution of star clusters with different ages across the weak spiral arms of NGC 628.

Age and evolution of diachronous erosion surfaces in the Amazon: Combining (U-Th)/He and cosmogenic 3He records

NASA Astrophysics Data System (ADS)

Monteiro, H. S.; Vasconcelos, P. M. P.; Farley, K. A.; Lopes, C. A. M.

2018-05-01

(U-Th)/He geochronology of two weathered plateaus in the Carajás Mountains, Pará, Brazil, reveals a history of weathering spanning from ca. 80 Ma to the present for this high elevation (∼720 m) land surface. Cosmogenic 3He measurements of hematite pebbles and blocks cemented onto the plateaus at two sites, N1 and S11D, yield erosion rates as low as 0.09 and 0.08 m Ma-1, respectively. Thus, these results confirm that the plateau surfaces are nearly immune to physical erosion for tens of millions of years. (U-Th)/He geochronology of ferruginous duricrusts blanketing the low elevation (250-100 m) plains surrounding the Carajás Mountains yield results consistently younger than ∼10 Ma. The geochronology results also reveal that the low elevation plain is diachronous, becoming progressively younger towards the receding plateaus. The spatial distribution of (U-Th)/He ages permits reconstruction of the history of scarp retreat for the Carajás landscape, showing that scarp retreat along major river valleys may have been as fast as 20 km Ma-1 during tectonically active and humid periods in the Cenozoic. The cessation of scarp retreat at some sites suggests that metamorphosed banded iron-formations and quartzites provide effective barriers to retreating escarpments, helping to preserve some of the oldest continuously exposed land surfaces on Earth.

Aging and interference in story recall.

PubMed

Mund, Iris; Bell, Raoul; Buchner, Axel

2012-01-01

BACKGROUND/STUDY CONTEXT: According to inhibitory deficit theory, older adults should be more impaired by visual distractors than younger adults when reading texts. Studies using a multiple-choice recognition test to examine age differences in the impairment of text comprehension due to distractor words yielded inconsistent results. In the present study, younger participants and older participants were required to read short texts comprising unrelated, related, or no distractor words. Visual acuity was equated between groups. Text recall was assessed using a gist-based propositional scoring procedure. There were pronounced age differences in reading with distraction. Older adults were slowed down more than younger adults by the presence of distractor words when reading. Furthermore, older adults' story recall was clearly impaired by the presence of distractor material, whereas younger adults' recall performance was not. In addition, older adults were more likely to make intrusion errors. Consistent with inhibitory deficit theory, the findings suggest that older adults were less able than younger adults to establish a correct mental representation of the target text when distractors were present. Furthermore, older adults were more likely than younger adults to build up incorrect memory representations that comprise distractor concepts. Thus, there are pronounced age differences in the impairment of text comprehension by distracting information.

Improving Tensile and Compressive Properties of an Extruded AZ91 Rod by the Combined Use of Torsion Deformation and Aging Treatment

PubMed Central

Song, Bo; Wang, Chunpeng; Guo, Ning; Pan, Hucheng; Xin, Renlong

2017-01-01

In this study, AZ91 magnesium alloy rods were used to investigate the effects of torsion deformation on microstructure and subsequent aging behavior. Extruded AZ91 rod has a uniform microstructure and typical fiber texture. Torsion deformation can generate a gradient microstructure on the cross-section of the rod. After torsion, from the center to the edge in the cross-section of the rod, both stored dislocations and area fraction of {10-12} twins gradually increase, and the basal pole of the texture tends to rotate in the ED direction. Direct aging usually generates coarse discontinuous precipitates and fine continuous precipitates simultaneously. Both twin structures and dislocations via torsion deformation can be effective microstructures for the nucleation of continuous precipitates during subsequent aging. Thus, aging after torsion can promote continuous precipitation and generate gradient precipitation characteristics. Both aging treatment and torsion deformation can reduce yield asymmetry, and torsion deformation enhances the aging hardening effect by promoting continuous precipitation. Therefore, combined use of torsion deformation and aging treatment can effectively enhance the yield strength and almost eliminate the yield asymmetry of the present extruded AZ91 rod. Finally, the relevant mechanisms are discussed. PMID:28772638

Connecting to young adults: an online social network survey of beliefs and attitudes associated with prescription opioid misuse among college students.

PubMed

Lord, Sarah; Brevard, Julie; Budman, Simon

2011-01-01

A survey of motives and attitudes associated with patterns of nonmedical prescription opioid medication use among college students was conducted on Facebook, a popular online social networking Web site. Response metrics for a 2-week random advertisement post, targeting students who had misused prescription medications, surpassed typical benchmarks for online marketing campaigns and yielded 527 valid surveys. Respondent characteristics, substance use patterns, and use motives were consistent with other surveys of prescription opioid use among college populations. Results support the potential of online social networks to serve as powerful vehicles to connect with college-aged populations about their drug use. Limitations of the study are noted.

Sulfur in vacuum - Sublimation effects on frozen melts, and applications to Io's surface and torus

NASA Technical Reports Server (NTRS)

Nash, Douglas B.

1987-01-01

Vacuum sublimation effects on solid sulfur yield a form of the element that is white at room temperature, is fluffy in texture, and forms on frozen sulfur in vacuum through differential evaporation of molecular species in the solid. This vacuum sulfur should exist in large quantity on Io, if the solid free sulfur there has solidified from a melt; a sulfur volcanism model for Io is accordingly developed on this basis which implies that the color and spectra of different sulfur regions of Io could indicate their relative crystallization ages and cooling histories. The flux of sublimating hotspot sulfur appears consistent with estimated turnover rates of the Io surface.

Lava-flow characterization at Pisgah Volcanic Field, California, with multiparameter imaging radar

USGS Publications Warehouse

Gaddis, L.R.

1992-01-01

Multi-incidence-angle (in the 25?? to 55?? range) radar data aquired by the NASA/JPL Airborne Synthetic Aperture Radar (AIRSAR) at three wavelengths simultaneously and displayed at three polarizations are examined for their utility in characterizing lava flows at Pisgah volcanic field, California. Pisgah lava flows were erupted in three phases; flow textures consist of hummocky pahoehoe, smooth pahoehoe, and aa (with and without thin sedimentary cover). Backscatter data shown as a function of relative age of Pisgah flows indicate that dating of lava flows on the basis of average radar backscatter may yield ambiguous results if primary flow textures and modification processes are not well understood. -from Author

Comparison of online and offline tests in LED accelerated reliability tests under temperature stress.

PubMed

Ke, Hong-Liang; Jing, Lei; Gao, Qun; Wang, Yao; Hao, Jian; Sun, Qiang; Xu, Zhi-Jun

2015-11-20

Accelerated aging tests are the main method used in the evaluation of LED reliability, and can be performed in either online or offline modes. The goal of this study is to provide the difference between the two test modes. In the experiments, the sample is attached to different heat sinks to acquire the optical parameters under different junction temperatures of LEDs. By measuring the junction temperature in the aging process (Tj1), and the junction temperature in the testing process (Tj2), we achieve consistency with an online test of Tj1 and Tj2 and a difference with an offline test of Tj1 and Tj2. Experimental results show that the degradation rate of the luminous flux rises as Tj2 increases, which yields a difference of projected life L(70%) of 8% to 13%. For color shifts over 5000 h of aging, the online test shows a larger variation of the distance from the Planckian locus, about 40% to 50% more than the normal test at an ambient temperature of 25°C.

Lu-Hf total-rock age for the Amîtsoq gneisses, West Greenland

USGS Publications Warehouse

Pettingill, H.S.; Patchett, P.J.

1981-01-01

Lu-Hf total-rock data for the Amîtsoq gneisses of West Greenland yield an age of 3.55±0.22Gy(2σ), based on the decay constant λ176Lu=1.96×10−11y−1, and an initial176Hf/177Hf ratio of 0.280482±33. The result is in good agreement with Rb-Sr total-rock and U-Pb zircon ages. In spite of severe metamorphism of the area at 2.9 Gy, zircons from two of the samples have remained on the total-rock line, and define points close to the initial Hf ratio. The initial176Hf/177Hf lies close to a chondritic Hf isotopic evolution curve from 4.55 Gy to present. This is consistent with the igneous precursors to the Amîtsoq gneisses having been derived from the mantle at or shortly before 3.6 Gy. Anomalous relationships between Hf concentration and the176Lu/177Hf ratio may suggest that trace element abundances in the Amîtsoq gneisses are partly controlled by processes related to metamorphism.

Neurobehavioral development in Joubert syndrome.

PubMed

Gitten, J; Dede, D; Fennell, E; Quisling, R; Maria, B L

1998-08-01

Research on children with Joubert syndrome has focused on brain structural abnormalities and associated clinical symptoms. The degree of developmental delay has not been objectively reported. We investigated the neurobehavioral development of children with Joubert syndrome through neurobehavioral assessment in the largest sample to date. Thirty-two parents of children with Joubert syndrome completed the Child Development Inventory and magnetic resonance imaging (MRI) data was gathered on 17 of these children. Results indicate that 94% were severely impaired according to the Child Development Inventory, with age being positively correlated with degree of neurobehavioral impairment. The average developmental age of our sample was 19 months (63% below chronological age). Severity of illness as measured by the General Development scale of the Child Development Inventory and severity of illness as measured by MRI (overall severity rating) did not yield consistent data regarding severity of the midbrain and cerebellar malformations. Similarly, markers of abnormal cerebral development such as cortical atrophy and delayed myelination were independent of severity of illness ratings on the Child Development Inventory. The degree of developmental delay in Joubert syndrome and the severity of gross central nervous system malformations appear independent.

Lu-Hf total-rock age for the Amitsoq gneisses, West Greenland

NASA Technical Reports Server (NTRS)

Pettingill, H. S.; Patchett, P. J.

1981-01-01

Lu-Hf total-rock data for the Amitsoq gneisses of West Greenland yield an age of 3.55 + or - 0.22 billion years, based on the decay constant for Lu-176 of 1.96 x 10 to the -11th/year, and an initial Hf-176/Hf-177 ratio of 0.280482 + or - 33. The result is in good agreement with Rb-Sr total-rock and U-Pb zircon ages. In spite of severe metamorphism of the area at 2.9 billion years, zircons from two of the samples have remained on the total-rock line, and define points close to the initial Hf ratio. The initial Hf-176/Hf-177 lies close to a chondritic Hf isotopic evolution curve from 4.55 billion years to present. This is consistent with the igneous precursors to the Amitsoq gneisses having been derived from the mantle at or shortly before 3.6 billion years. Anomalous relationships between Hf concentration and the Lu-176/Hf-177 ratio may suggest that trace element abundances in the Amitsoq gneisses are partly controlled by processes related to metamorphism.

Constraining planetary migration and tidal dissipation with coeval hot Jupiters

NASA Astrophysics Data System (ADS)

O'Connor, Christopher E.; Hansen, Bradley M. S.

2018-06-01

We investigate the constraints on the formation of, and tidal dissipation processes in, hot Jupiters (HJs) that can be inferred based on reliable knowledge of the age of a system or population. Particular attention is paid to the role of young systems (such as those in open clusters or star-forming regions) in such studies. For an ensemble of coeval HJ (or proto-HJ) systems, we quantify the effect of age on the distribution of orbital eccentricities with respect to orbital periods as well as the location of the observed `pile-up' feature. We expect the effects of pre-main-sequence stellar evolution to be important only if a substantial fraction of HJs approach their current orbits early in protostellar contraction (ages ≲ 10 Myr). Application to the HJs presently known in the cluster M 67 yields constraints on the dissipation roughly consistent with those gleaned from planets in the field; for those in the Hyades and Praesepe, our results suggest a higher degree of dissipation at early times than that inferred from other populations.

Precise K-Ar, 40Ar/39Ar, Rb-Sr and U/Pb mineral ages from the 27.5 Ma fish canyon tuff reference standard

USGS Publications Warehouse

Lanphere, M.A.; Baadsgaard, H.

2001-01-01

The accuracy of ages measured using the 40Ar/39Ar technique is affected by uncertainties in the age of radiation fluence-monitor minerals. At present, there is lack of agreement about the ages of certain minerals used as fluence monitors. The accuracy of the age of a standard may be improved if the age can be measured using different decay schemes. This has been done by measuring ages on minerals from the Oligocene Fish Canyon Tuff (FCT) using the K-Ar, 40Ar/39Ar. Rb-Sr and U/Pb methods. K-Ar and 40Ar/39Ar total fusion ages of sanidine, biotite and hornblende yielded a mean age of 27.57 ?? 0.36 Ma. The weighted mean 40Ar/39Ar plateau age of sanidine and biotite is 27.57 ?? 0.18 Ma. A biotite-feldspar Rb-Sr isochron yielded an age of 27.44 ?? 0.16 Ma. The U-Pb data for zircon are complex because of the presence of Precambrian zircons and inheritance of radiogenic Pb. Zircons with 207Pb/235U < 0.4 yielded a discordia line with a lower concordia intercept of 27.52 ?? 0.09 Ma. Evaluation of the combined data suggests that the best age for FCT is 27.51 Ma. Published by Elsevier Science B.V.

Comparison of Online Survey Recruitment Platforms for Hard-to-Reach Pregnant Smoking Populations: Feasibility Study

PubMed Central

Agas, Jessica Marie; Lee, Melissa; Pan, Julia Lily; Buttenheim, Alison Meredith

2018-01-01

Background Recruiting hard-to-reach populations for health research is challenging. Web-based platforms offer one way to recruit specific samples for research purposes, but little is known about the feasibility of online recruitment and the representativeness and comparability of samples recruited through different Web-based platforms. Objective The objectives of this study were to determine the feasibility of recruiting a hard-to-reach population (pregnant smokers) using 4 different Web-based platforms and to compare participants recruited through each platform. Methods A screener and survey were distributed online through Qualtrics Panel, Soapbox Sample, Reddit, and Amazon Mechanical Turk (mTurk). Descriptive statistics were used to summarize results of each recruitment platform, including eligibility yield, quality yield, income, race, age, and gestational age. Results Of the 3847 participants screened for eligibility across all 4 Web-based platforms, 535 were eligible and 308 completed the survey. Amazon mTurk yielded the fewest completed responses (n=9), 100% (9/9) of which passed several quality metrics verifying pregnancy and smoking status. Qualtrics Panel yielded 14 completed responses, 86% (12/14) of which passed the quality screening. Soapbox Sample produced 107 completed surveys, 67% (72/107) of which were found to be quality responses. Advertising through Reddit produced the highest completion rate (n=178), but only 29.2% (52/178) of those surveys passed the quality metrics. We found significant differences in eligibility yield, quality yield, age, number of previous pregnancies, age of smoking initiation, current smokers, race, education, and income (P<.001). Conclusions Although each platform successfully recruited pregnant smokers, results varied in quality, cost, and percentage of complete responses. Moving forward, investigators should pay careful attention to the percentage yield and cost of online recruitment platforms to maximize internal and external validity. PMID:29661751

Age and origin of anorthosites, charnockites, and granulites in the Central Virginia Blue Ridge: Nd and Sr isotopic evidence

USGS Publications Warehouse

Pettingill, H.S.; Sinha, A.K.; Tatsumoto, M.

1984-01-01

Rb-Sr isotopic data for anorthosites, charnockites, ferrodioritic to quartz monzonitic plutons, and high-grade gneisses of the Blue Ridge of central Virginia show evidence of post-emplacement metamorphism, but in some cases retain Grenville ages. The Pedlar River Charnockite Suite yields an isochron age of 1021 +/-36 Ma, (initial 87Sr/86Sr ratio of 0.7047 +/-6), which agrees with published U-Pb zircon ages. Five samples of that unit which contain Paleozoic mylonitic fabrics define a regression line of 683 Ma, interpreted as a mixing line with no age significance. Samples of the Roseland Anorthosite Complex show excessive scatter on a Rb-Sr evolution diagram probably due to Paleozoic (475 m.y.) metamorphism. Data from the ferrodioritic to quartz monzonitic plutons of the area yield an age of 1009 +/-26 Ma (inital ratio=0.7058 +/-4), which is in the range of the U-Pb zircon ages of 1000-1100 Ma. The Stage Road Layered Gneiss yields an age of 1147 +/-34 Ma (initial ratio of 0.7047 +/- 5). Sm-Nd data for the Pedlar River Charnockite Suite reflect a pre-Grenville age of 1489 +/-118 Ma (e{open}Nd=+6.7 +/-1.2). Data for the Roseland Anorthosite Complex and the ferrodioritic to quartz monzonitic plutons yield Grenville isochron ages of 1045 +/44 Ma (e{open}Nd=+1.0 +/-0.3) and 1027 +/-101 Ma (e{open}Nd=+1.4 +/-1.0), respectively. Two Roseland Anorthosite samples plot far above the isochron, demonstrating the effects of post-emplacement disturbance of Sm-Nd systematics, while mylonitized Pedlar River Charnockite Suite samples show no evidence of Sm-Nd redistribution. The disparity of the Sm-Nd age and other isotopic ages for the Pedlar River Charnockite Suite probably reflects a Sm-Nd "source" age, suggesting the presence of an older crust within this portion of the ca. 1 Ga old basement. ?? 1984 Springer-Verlag.

The effect of SEM imaging on the Ar/Ar system in feldspars

NASA Astrophysics Data System (ADS)

Flude, S.; Sherlock, S.; Lee, M.; Kelley, S. P.

2010-12-01

Complex microtextures form in K-feldspar crystals as they cool and are affected by deuteric alteration. This complex structure is the cause of variable closure temperatures for Ar-Ar, a phenomenon which has been utilized in multi domain diffusion (MDD) modelling to recover thermal histories [1]. However, there has been substantial controversy regarding the precise interaction between feldspar microtextures and Ar-diffusion [2,3]. A number of studies have addressed this issue using coupled SEM imaging and Ar/Ar UV laser ablation microprobe (UV-LAMP) analysis on the same sample, to enable direct comparison of microtextures with Ar/Ar age data [4]. Here we have tested the idea that SEM work may affect Ar/Ar ages, leading to inaccurate results in subsequent Ar/Ar analyses. Three splits of alkali feldspar from the Dartmoor Granite in SW England were selected for Ar/Ar UV-LAMP analysis. Split 1 (“control”) was prepared as a polished thick section for Ar/Ar analysis. Split 2 (“SEM”) was prepared as a polished thick section, was chemically-mechanically polished with colloidal silica and underwent SEM imaging (uncoated) and focussed ion beam (FIB) milling (gold coated); electron beam damage in the SEM was maximised by leaving the sample at high magnification for eight minutes. Split 3 (“Etch”) is a cleavage fragment that was etched with HF vapour and underwent low to moderate magnification SEM imaging. The control split gave a range of laser-spot ages consistent with the expected cooling age of the granite and high yields of radiogenic 40Ar* (>90%). The area of the “SEM” split that experienced significant electron beam damage gave younger than expected ages and 40Ar* yields as low as 57%. These are interpreted as a combination of implantation of atmospheric Ar and local redistribution of K within the sample. The area of “SEM” that underwent FIB milling gave ages and 40Ar* yields comparable to the control split, suggesting that the Au-coat minimises FIB damage and that colloidal-polishing and low-magnification SEM imaging do not affect the Ar/Ar system. The “Etch” split gave younger than expected ages and 40Ar* yields as low as 58%, suggesting that HF etching also disrupts the Ar/Ar system. These results suggest that SEM techniques involving intense electron bombardment of an uncoated sample, such as charge contrast imaging and electron backscatter diffraction (EBSD), may disrupt the Ar/Ar system in the sample, leading to spurious results. Etching samples with HF, as is often done for routine Ar/Ar preparation of volcanic phenocrysts, introduces atmospheric Ar and may result in differential loss or gain of K and Ar isotopes, leading to spurious results. References [1] Lovera and Richter, 1989, J. Geophys. Res. 94, 17917-17935. [2] Parsons. et al., 1999, Cont. Min. Pet. 136, 92-110. [3] Mark et al., 2008, Geochim. Cosmochim. Acta, 72 2695-2710. [4] Reddy et al., 2001, Cont. Min. Pet., 141 186-200.

Thidiazuron (TDZ) increases fruit set and yield of 'Hosui' and 'Packham's Triumph' pear trees.

PubMed

Pasa, Mateus S; Silva, Carina P DA; Carra, Bruno; Brighenti, Alberto F; Souza, André Luiz K DE; Petri, José Luiz

2017-01-01

The low fruit set is one of the main factors leading to poor yield of pear orchards in Brazil. The exogenous application of thidiazuron (TDZ) and aminoethoxyvinilglycine (AVG) has shown promising results in some pear cultivars and other temperate fruit trees. The objective of this study was to evaluate the effect of TDZ and AVG on fruit set, yield, and fruit quality of 'Hosui' and 'Packham's Triumph' pears. The study was performed in a commercial orchard located in São Joaquim, SC. Plant material consisted of 'Hosui' and 'Packham's Triumph' pear trees grafted on Pyrus calleryana. Treatments consisted on different rates of TDZ (0 mg L-1, 20 mg L-1, 40 mg L-1 and 60 mg L-1) sprayed at full bloom for both cultivars. An additional treatment of AVG 60 mg L-1 was sprayed one week after full bloom in 'Hosui'. The fruit set, number of fruit per tree, yield, fruit weight, seed number, and fruit quality attributes were assessed. Fruit set and yield of both cultivars are consistently increased by TDZ, within the rates of 20 to 60 mg L-1. Besides, its application increased fruit size of 'Hosui' and did not negatively affect fruit quality attributes of both cultivars.

Investigation of inconsistent ENDF/B-VII.1 independent and cumulative fission product yields with proposed revisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pigni, Marco T; Francis, Matthew W; Gauld, Ian C

A recent implementation of ENDF/B-VII. independent fission product yields and nuclear decay data identified inconsistencies in the data caused by the use of updated nuclear scheme in the decay sub-library that is not reflected in legacy fission product yield data. Recent changes in the decay data sub-library, particularly the delayed neutron branching fractions, result in calculated fission product concentrations that are incompatible with the cumulative fission yields in the library, and also with experimental measurements. A comprehensive set of independent fission product yields was generated for thermal and fission spectrum neutron induced fission for 235,238U and 239,241Pu in order tomore » provide a preliminary assessment of the updated fission product yield data consistency. These updated independent fission product yields were utilized in the ORIGEN code to evaluate the calculated fission product inventories with experimentally measured inventories, with particular attention given to the noble gases. An important outcome of this work is the development of fission product yield covariance data necessary for fission product uncertainty quantification. The evaluation methodology combines a sequential Bayesian method to guarantee consistency between independent and cumulative yields along with the physical constraints on the independent yields. This work was motivated to improve the performance of the ENDF/B-VII.1 library in the case of stable and long-lived cumulative yields due to the inconsistency of ENDF/B-VII.1 fission p;roduct yield and decay data sub-libraries. The revised fission product yields and the new covariance data are proposed as a revision to the fission yield data currently in ENDF/B-VII.1.« less

Nonlinear programming models to optimize uneven-aged loblolly pine management

Treesearch

Benedict J. Schulte; Joseph. Buongiorno; Kenneth Skog

1999-01-01

Nonlinear programming models of uneven-aged loblolly pine (Pinus taeda L.) management were developed to identify sustainable management regimes which optimize: 1) soil expectation value (SEV), 2) tree diversity, or 3) annual sawtimber yields. The models use the equations of SouthPro, a site- and density-dependent, multi-species matrix growth and yield model that...

Additive survival least square support vector machines: A simulation study and its application to cervical cancer prediction

NASA Astrophysics Data System (ADS)

Khotimah, Chusnul; Purnami, Santi Wulan; Prastyo, Dedy Dwi; Chosuvivatwong, Virasakdi; Sriplung, Hutcha

2017-11-01

Support Vector Machines (SVMs) has been widely applied for prediction in many fields. Recently, SVM is also developed for survival analysis. In this study, Additive Survival Least Square SVM (A-SURLSSVM) approach is used to analyze cervical cancer dataset and its performance is compared with the Cox model as a benchmark. The comparison is evaluated based on the prognostic index produced: concordance index (c-index), log rank, and hazard ratio. The higher prognostic index represents the better performance of the corresponding methods. This work also applied feature selection to choose important features using backward elimination technique based on the c-index criterion. The cervical cancer dataset consists of 172 patients. The empirical results show that nine out of the twelve features: age at marriage, age of first getting menstruation, age, parity, type of treatment, history of family planning, stadium, long-time of menstruation, and anemia status are selected as relevant features that affect the survival time of cervical cancer patients. In addition, the performance of the proposed method is evaluated through a simulation study with the different number of features and censoring percentages. Two out of three performance measures (c-index and hazard ratio) obtained from A-SURLSSVM consistently yield better results than the ones obtained from Cox model when it is applied on both simulated and cervical cancer data. Moreover, the simulation study showed that A-SURLSSVM performs better when the percentage of censoring data is small.

An extremely low U Pb source in the Moon: UThPb, SmNd, RbSr, and 40Ar 39Ar isotopic systematics and age of lunar meteorite Asuka 881757

USGS Publications Warehouse

Misawa, K.; Tatsumoto, M.; Dalrymple, G.B.; Yanai, K.

1993-01-01

We have undertaken UThPb, SmNd, RbSr, and 40Ar 39Ar isotopic studies on Asuka 881757, a coarse-grained basaltic lunar meteorite whose chemical composition is close to low-Ti and very low-Ti (VLT) mare basalts. The PbPb internal isochron obtained for acid leached residues of separated mineral fractions yields an age of 3940 ?? 28 Ma, which is similar to the U-Pb (3850 ?? 150 Ma) and Th-Pb (3820 ?? 290 Ma) internal isochron ages. The Sm-Nd data for the mineral separates yield an internal isochron age of 3871 ?? 57 Ma and an initial 143Nd 144Nd value of 0.50797 ?? 10. The Rb-Sr data yield an internal isochron age of 3840 ?? 32 Ma (??(87Rb) = 1.42 ?? 10-11 yr-1) and a low initial 87Sr 86Sr ratio of 0.69910 ?? 2. The 40Ar 39Ar age spectra for a glass fragment and a maskelynitized plagioclase are relatively flat and give a weighted mean plateau age of 3798 ?? 12 Ma. We interpret these ages to indicate that the basalt crystallized from a melt 3.87 Ga ago (the Sm-Nd age) and an impact event disturbed the Rb-Sr system and completely reset the K-Ar system at 3.80 Ga. The slightly higher Pb-Pb age compared to the Sm-Nd age could be due to the secondary Pb (from terrestrial and/or lunar surface Pb contamination) that remained in the residues after acid leaching. Alternatively, the following interpretation is also possible; the meteorite crystallized at 3.94 Ga (the Pb-Pb age) and the Sm-Nd, Rb-Sr, and K-Ar systems were disturbed by an impact event at 3.80 Ga. The crystallization age obtained here is older than those reported for low-Ti basalts (3.2-3.5 Ga) and for VLT basalts (3.4 Ga), but similar to ages of some mare basalts, indicating that the basalt may have formed from a magma related to a basin-forming event (Imbrium?). The age span for VLT basalts from different sampling sites suggest that they were erupted over a wide area during an interval of at least ~500 million years. The impact event that thermally reset the K-Ar system of Asuka 881757 must have been post-Imbrium (perhaps Orientale) in age. The lead isotopic composition of Asuka 881757 is nonradiogenic compared with typical Apollo mare basalts and the estimated 238U 204Pb (??) value for the basalt source is 10 ?? 3. This source-?? value is the lowest so far measured for lunar rocks. A large positive ??{lunate}Nd value (7.4 ?? 0.5) and the time averaged 147Sm 144Nd ratio for the basalt source are similar to those for some Apollo 12, 15, and 17 basalts, suggesting a LREE-depleted mantle, which is consistent with the global magma ocean hypothesis. The U-Th-Pb, Sm-Nd, and Rb-Sr data on Asuka 881757 suggest that the basalt was derived from a low U Pb, low Rb Sr, and high Sm Nd source region, mainly composed of olivine and orthopyroxene with minor amounts of plagioclase (or clinopyroxene) and with sulfides enriched in volatile chalcophile elements. The basalt source may be deep in origin and different in chemistry from those previously estimated from studies of Apollo and Luna mare basalts, indicating heterogeneous sources for mare basalts. ?? 1993.

Investigation of Inconsistent ENDF/B-VII.1 Independent and Cumulative Fission Product Yields with Proposed Revisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pigni, M.T., E-mail: pignimt@ornl.gov; Francis, M.W.; Gauld, I.C.

A recent implementation of ENDF/B-VII.1 independent fission product yields and nuclear decay data identified inconsistencies in the data caused by the use of updated nuclear schemes in the decay sub-library that are not reflected in legacy fission product yield data. Recent changes in the decay data sub-library, particularly the delayed neutron branching fractions, result in calculated fission product concentrations that do not agree with the cumulative fission yields in the library as well as with experimental measurements. To address these issues, a comprehensive set of independent fission product yields was generated for thermal and fission spectrum neutron-induced fission for {supmore » 235,238}U and {sup 239,241}Pu in order to provide a preliminary assessment of the updated fission product yield data consistency. These updated independent fission product yields were utilized in the ORIGEN code to compare the calculated fission product inventories with experimentally measured inventories, with particular attention given to the noble gases. Another important outcome of this work is the development of fission product yield covariance data necessary for fission product uncertainty quantification. The evaluation methodology combines a sequential Bayesian method to guarantee consistency between independent and cumulative yields along with the physical constraints on the independent yields. This work was motivated to improve the performance of the ENDF/B-VII.1 library for stable and long-lived fission products. The revised fission product yields and the new covariance data are proposed as a revision to the fission yield data currently in ENDF/B-VII.1.« less

The mesoproterozoic Beaverhead impact structure and its tectonic setting, Montana-Idaho: 40Ar/39 and U-Pb isotopic constraints

USGS Publications Warehouse

Kellogg, K.S.; Snee, L.W.; Unruh, D.M.

2003-01-01

New 40Ar/39Ar and uranium-lead (U-Pb) zircon data from the Beaverhead impact structure, first identified by extensive shatter coning of Proterozoic quartzite and gneiss from the Beaverhead Mountains near the Montana-Idaho border, indicate that the structure formed at or after 900 Ma. The 40Ar/39Ar age spectra from fine-grained muscovite and biotite from a breccia zone in high-grade gneiss show significant argon loss but yield dates for highest-temperature steps that cluster between 899 and 908 Ma. The dated minerals probably formed by recrystallization of impact glass, so on both geologic and isotopic grounds, the dates probably represent the minimum age of impact. U-Pb data for zircons from the same breccia are strongly discordant and yield an upper intercept apparent age of 2464 ?? 56 Ma and a lower intercept apparent age of 779 ?? 69 Ma. Another brecciated gneiss about 7 km to the northeast that does not contain secondary mica does contain zircons that yield a concordant apparent age of 2455 ?? 9 Ma. Nearby gneiss that neither is brecciated nor contains shatter cones yields an apparent age of 2451 ?? 46 Ma. The 40Ar/39Ar results constrain the age of the shatter-coned quartzite and indicate that it is >900 Ma and possibly correlative with the Gunsight Formation of the Mesoproterozoic Lemhi Group. The upper intercept U-Pb age of ???2450 Ma from all three dated samples also shows that the Paleoproterozoic basement rocks of the area are among the youngest in the mostly Archean Wyoming province of North America. The impact site lies near the margin of the province, along the northeast-trending Great Falls tectonic zone, and the relatively young crustal age may reflect Early Proterozoic marginal accretion.

A comparison of three methods of assessing differential item functioning (DIF) in the Hospital Anxiety Depression Scale: ordinal logistic regression, Rasch analysis and the Mantel chi-square procedure.

PubMed

Cameron, Isobel M; Scott, Neil W; Adler, Mats; Reid, Ian C

2014-12-01

It is important for clinical practice and research that measurement scales of well-being and quality of life exhibit only minimal differential item functioning (DIF). DIF occurs where different groups of people endorse items in a scale to different extents after being matched by the intended scale attribute. We investigate the equivalence or otherwise of common methods of assessing DIF. Three methods of measuring age- and sex-related DIF (ordinal logistic regression, Rasch analysis and Mantel χ(2) procedure) were applied to Hospital Anxiety Depression Scale (HADS) data pertaining to a sample of 1,068 patients consulting primary care practitioners. Three items were flagged by all three approaches as having either age- or sex-related DIF with a consistent direction of effect; a further three items identified did not meet stricter criteria for important DIF using at least one method. When applying strict criteria for significant DIF, ordinal logistic regression was slightly less sensitive. Ordinal logistic regression, Rasch analysis and contingency table methods yielded consistent results when identifying DIF in the HADS depression and HADS anxiety scales. Regardless of methods applied, investigators should use a combination of statistical significance, magnitude of the DIF effect and investigator judgement when interpreting the results.

Age and evolution of the lithospheric mantle beneath the Khanka Massif: Geochemical and Re-Os isotopic evidence from Sviyagino mantle xenoliths

NASA Astrophysics Data System (ADS)

Guo, Peng; Xu, Wen-Liang; Wang, Chun-Guang; Wang, Feng; Ge, Wen-Chun; Sorokin, A. A.; Wang, Zhi-Wei

2017-06-01

New geochemical and Re-Os isotopic data of mantle xenoliths entrained in Cenozoic Sviyagino alkali basalts from the Russian Far East provide insights into the age and evolution of the sub-continental lithospheric mantle (SCLM) beneath the Khanka Massif, within the Central Asian Orogenic Belt (CAOB). These mantle xenoliths are predominantly spinel lherzolites with minor spinel harzburgite. The lherzolites contain high whole-rock concentrations of Al2O3 and CaO, with low forsterite content in olivine (Fo = 89.5-90.3%) and low Cr# in spinel (0.09-0.11). By contrast, the harzburgite is more refractory, containing lower whole rock Al2O3 and CaO contents, with higher Fo (91.3%) and spinel Cr# (0.28). Their whole rock and mineral compositions suggest that the lherzolites experienced low-degree (1-4%) batch melting and negligible metasomatism, whereas the harzburgite underwent a higher degree (10%) of fractional melting, and experienced minor post-melting silicate metasomatism. Two-pyroxene rare earth element (REE)-based thermometry (TREE) yields predominant equilibrium temperatures of 884-1043 °C, similar to values obtained from two-pyroxene major element-based thermometry (TBKN = 942-1054 °C). Two lherzolite samples yield high TREE relative to TBKN (TREE - TBKN ≥ 71 °C), suggesting that they cooled rapidly as a result of the upwelling of hot asthenospheric mantle material that underplated a cold ancient lithosphere. The harzburgite with a low Re/Os value has an 187Os/188Os ratio of 0.11458, yielding an Os model age (TMA) relative to the primitive upper mantle (PUM) of 2.09 Ga, and a Re depletion ages (TRD) of 1.91 Ga; both of which record ancient melt depletion during the Paleoproterozoic ( 2.0 Ga). The 187Os/188Os values of lherzolites (0.12411-0.12924) correlate well with bulk Al2O3 concentrations and record the physical mixing of ancient mantle domains and PUM-like ambient mantle material within the asthenosphere. This indicates that the SCLM beneath the Khanka Massif had been formed since at least the Paleoproterozoic ( 2.0 Ga), and was replaced by juvenile (Phanerozoic) mantle material accreted from the asthenosphere. The synthesis of available TRD ages for mantle-derived rocks and sulfides in xenoliths is consistent with the prior existence of a common Paleoproterozoic ( 2.0 Ga) SCLM beneath the eastern CAOB. Finally, comparing of mantle TRD ages and the ages of crustal rocks suggests temporal and genetic links between crust and mantle formation during the evolution of the CAOB.

Unraveling the Age Hardening Response in U-Nb Alloys

DOE PAGES

Hackenberg, Robert Errol; Hemphill, Geralyn M. Sewald; Forsyth, Robert Thomas; ...

2016-11-15

Complicating factors that have stymied understanding of uranium-niobium’s aging response are briefly reviewed, including (1) niobium inhomogeneity, (2) machining damage effects on tensile properties, (3) early-time transients of ductility increase, and (4) the variety of phase transformations. A simple Logistic-Arrhenius model was applied to predict yield and ultimate tensile strengths and tensile elongation of U-4Nb as a function of thermal age. Lastly, fits to each model yielded an apparent activation energy that was compared with phase transformation mechanisms.

Understanding the Connection Between Traumatic Brain Injury and Alzheimer’s Disease: A Population-Based Medical Record Review Analysis

DTIC Science & Technology

2017-10-01

individuals with a confirmed TBI to age- and sex -matched individuals from the population without a TBI. Target completion 6-24-months f. Determine...reviewed, yielding 1,428 confirmed cases (yield rate of 26%). 3 e. Match individuals with a confirmed TBI to age- and sex -matched individuals...a confirmed TBI to two (2) age- and sex -matched individuals from the population without a TBI. b. For TBI events that were associated with other

Quantitative analysis of relationships between irradiation parameters and the reproducibility of cyclotron-produced (99m)Tc yields.

PubMed

Tanguay, J; Hou, X; Buckley, K; Schaffer, P; Bénard, F; Ruth, T J; Celler, A

2015-05-21

Cyclotron production of (99m)Tc through the (100)Mo(p,2n) (99m)Tc reaction channel is actively being investigated as an alternative to reactor-based (99)Mo generation by nuclear fission of (235)U. An exciting aspect of this approach is that it can be implemented using currently-existing cyclotron infrastructure to supplement, or potentially replace, conventional (99m)Tc production methods that are based on aging and increasingly unreliable nuclear reactors. Successful implementation will require consistent production of large quantities of high-radionuclidic-purity (99m)Tc. However, variations in proton beam currents and the thickness and isotopic composition of enriched (100)Mo targets, in addition to other irradiation parameters, may degrade reproducibility of both radionuclidic purity and absolute (99m)Tc yields. The purpose of this article is to present a method for quantifying relationships between random variations in production parameters, including (100)Mo target thicknesses and proton beam currents, and reproducibility of absolute (99m)Tc yields (defined as the end of bombardment (EOB) (99m)Tc activity). Using the concepts of linear error propagation and the theory of stochastic point processes, we derive a mathematical expression that quantifies the influence of variations in various irradiation parameters on yield reproducibility, quantified in terms of the coefficient of variation of the EOB (99m)Tc activity. The utility of the developed formalism is demonstrated with an example. We show that achieving less than 20% variability in (99m)Tc yields will require highly-reproducible target thicknesses and proton currents. These results are related to the service rate which is defined as the percentage of (99m)Tc production runs that meet the minimum daily requirement of one (or many) nuclear medicine departments. For example, we show that achieving service rates of 84.0%, 97.5% and 99.9% with 20% variations in target thicknesses requires producing on average 1.2, 1.5 and 1.9 times the minimum daily activity requirement. The irradiation parameters that would be required to achieve these service rates are described. We believe the developed formalism will aid in the development of quality-control criteria required to ensure consistent supply of large quantities of high-radionuclidic-purity cyclotron-produced (99m)Tc.

Quantitative analysis of relationships between irradiation parameters and the reproducibility of cyclotron-produced 99mTc yields

NASA Astrophysics Data System (ADS)

Tanguay, J.; Hou, X.; Buckley, K.; Schaffer, P.; Bénard, F.; Ruth, T. J.; Celler, A.

2015-05-01

Cyclotron production of 99mTc through the 100Mo(p,2n) 99mTc reaction channel is actively being investigated as an alternative to reactor-based 99Mo generation by nuclear fission of 235U. An exciting aspect of this approach is that it can be implemented using currently-existing cyclotron infrastructure to supplement, or potentially replace, conventional 99mTc production methods that are based on aging and increasingly unreliable nuclear reactors. Successful implementation will require consistent production of large quantities of high-radionuclidic-purity 99mTc. However, variations in proton beam currents and the thickness and isotopic composition of enriched 100Mo targets, in addition to other irradiation parameters, may degrade reproducibility of both radionuclidic purity and absolute 99mTc yields. The purpose of this article is to present a method for quantifying relationships between random variations in production parameters, including 100Mo target thicknesses and proton beam currents, and reproducibility of absolute 99mTc yields (defined as the end of bombardment (EOB) 99mTc activity). Using the concepts of linear error propagation and the theory of stochastic point processes, we derive a mathematical expression that quantifies the influence of variations in various irradiation parameters on yield reproducibility, quantified in terms of the coefficient of variation of the EOB 99mTc activity. The utility of the developed formalism is demonstrated with an example. We show that achieving less than 20% variability in 99mTc yields will require highly-reproducible target thicknesses and proton currents. These results are related to the service rate which is defined as the percentage of 99mTc production runs that meet the minimum daily requirement of one (or many) nuclear medicine departments. For example, we show that achieving service rates of 84.0%, 97.5% and 99.9% with 20% variations in target thicknesses requires producing on average 1.2, 1.5 and 1.9 times the minimum daily activity requirement. The irradiation parameters that would be required to achieve these service rates are described. We believe the developed formalism will aid in the development of quality-control criteria required to ensure consistent supply of large quantities of high-radionuclidic-purity cyclotron-produced 99mTc.

The relative contributions of non-enzymatic glycation and cortical porosity on the fracture toughness of aging bone

PubMed Central

Tang, S.Y.; Vashishth, D.

2010-01-01

The risk of fracture increases with age due to the decline of bone mass and bone quality. One of the age-related changes in bone quality occurs through the formation and accumulation of advanced glycation end-products (AGEs) due to non-enzymatic glycation (NEG). However as a number of other changes including increased porosity occur with age and affect bone fragility, the relative contribution of AGEs on the fracture resistance of aging bone is unknown. Using a high-resolution nonlinear finite element model that incorporate cohesive elements and micro-computed tomography-based 3d meshes, we investigated the contribution of AGEs and cortical porosity on the fracture toughness of human bone. The results show that NEG caused a 52% reduction in propagation fracture toughness (R-curve slope). The combined effects of porosity and AGEs resulted in an 88% reduction in propagation toughness. These findings are consistent with previous experimental results. The model captured the age-related changes in the R-curve toughening by incorporating bone quantity and bone quality changes, and these simulations demonstrate the ability of the cohesive models to account for the irreversible dynamic crack growth processes affected by the changes in post-yield material behavior. By decoupling the matrix-level effects due to NEG and intracortical porosity, we are able to directly determine the effects of NEG on fracture toughness. The outcome of this study suggests that it may be important to include the age-related changes in the material level properties by using finite element analysis towards the prediction of fracture risk. PMID:21056419

Quantification of the Dedolomitization Rate for Correction of Groundwater 14C Ages in Aquifers of the Sacramento Mountains, New Mexico

NASA Astrophysics Data System (ADS)

Morse, J. T.; Phillips, F. M.; Land, L. A.

2009-12-01

Ion chemistry of groundwater from the western part of the Roswell Basin, New Mexico, are consistent with groundwater quality evolution driven by dedolomitization. Measured, uncorrected, 14C values in groundwater yield an apparent residence time of 4700 years for the western part of the Roswell Basin. We have employed a simple model incorporating the changes in bicarbonate, magnesium and 14C along the flow-path to quantify the in-situ rate of dedolomitization and thereby to correct the 14C values for inorganic carbon dilution. The model yielded a corrected residence time of 1300 years at the distal end of the flowpath and a regional hydraulic conductivity of 5×10-4cm/s. Prior studies have inferred that underflow from the Sacramento Mountains constitutes an important component of recharge to the Artesian Aquifer of the Roswell Basin but it has not been possible to quantify this contribution. The information from the corrected 14C dating will allow an improved assessment of the groundwater resources available in this overstressed basin.

40Ar ∗ loss in experimentally deformed muscovite and biotite with implications for 40Ar/ 39Ar geochronology of naturally deformed rocks

NASA Astrophysics Data System (ADS)

Cosca, Michael; Stunitz, Holger; Bourgeix, Anne-Lise; Lee, John P.

2011-12-01

The effects of deformation on radiogenic argon ( 40Ar ∗) retentivity in mica are described from high pressure experiments performed on rock samples of peraluminous granite containing euhedral muscovite and biotite. Cylindrical cores, ˜15 mm in length and 6.25 mm in diameter, were drilled from granite collected from the South Armorican Massif in northwestern France, loaded into gold capsules, and weld-sealed in the presence of excess water. The samples were deformed at a pressure of 10 kb and a temperature of 600 °C over a period 29 of hours within a solid medium assembly in a Griggs-type triaxial hydraulic deformation apparatus. Overall shortening in the experiments was approximately 10%. Transmitted light and secondary and backscattered electron imaging of the deformed granite samples reveals evidence of induced defects and for significant physical grain size reduction by kinking, cracking, and grain segmentation of the micas. Infrared (IR) laser (CO 2) heating of individual 1.5-2.5 mm diameter grains of muscovite and biotite separated from the undeformed granite yield well-defined 40Ar/ 39Ar plateau ages of 311 ± 2 Ma (2σ). Identical experiments on single grains separated from the experimentally deformed granite yield results indicating 40Ar ∗ loss of 0-35% in muscovite and 2-3% 40Ar ∗ loss in biotite. Intragrain in situ ultraviolet (UV) laser ablation 40Ar/ 39Ar ages (±4-10%, 1σ) of deformed muscovites range from 309 ± 13 to 264 ± 7 Ma, consistent with 0-16% 40Ar ∗ loss relative to the undeformed muscovite. The in situ UV laser ablation 40Ar/ 39Ar ages of deformed biotite vary from 301 to 217 Ma, consistent with up to 32% 40Ar ∗ loss. No spatial correlation is observed between in situ40Ar/ 39Ar age and position within individual grains. Using available argon diffusion data for muscovite the observed 40Ar ∗ loss in the experimentally treated muscovite can be utilized to predict average 40Ar ∗ diffusion dimensions. Maximum 40Ar/ 39Ar ages obtained by UV laser ablation overlap those of the undeformed muscovite, indicating argon loss of <1% and an average effective grain radius for 40Ar ∗ diffusion ⩾700 μm. The UV laser ablation and IR laser incremental 40Ar/ 39Ar ages indicating 40Ar ∗ loss of 16% and 35%, respectively, are consistent with an average diffusion radius ≪100 μm. These results support a hypothesis of grain-scale 40Ar ∗ diffusion distances in undeformed mica and a heterogeneous mechanical reduction in the intragrain effective diffusion length scale for 40Ar ∗ in deformed mica. Reduction in the effective diffusion length scale in naturally deformed samples occurs most probably through production of mesoscopic and submicroscopic defects such as, e.g., stacking faults. A network of interconnected defects, continuously forming and annealing during dynamic deformation likely plays an important role in controlling both 40Ar ∗ retention and intragrain distribution in deformed mica. Intragrain 40Ar/ 39Ar ages, when combined with estimates of diffusion kinetics and distances, may provide a means of establishing thermochronological histories from individual micas.

Bayesian investigation of isochrone consistency using the old open cluster NGC 188

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hills, Shane; Courteau, Stéphane; Von Hippel, Ted

2015-03-01

This paper provides a detailed comparison of the differences in parameters derived for a star cluster from its color–magnitude diagrams (CMDs) depending on the filters and models used. We examine the consistency and reliability of fitting three widely used stellar evolution models to 15 combinations of optical and near-IR photometry for the old open cluster NGC 188. The optical filter response curves match those of theoretical systems and are thus not the source of fit inconsistencies. NGC 188 is ideally suited to this study thanks to a wide variety of high-quality photometry and available proper motions and radial velocities thatmore » enable us to remove non-cluster members and many binaries. Our Bayesian fitting technique yields inferred values of age, metallicity, distance modulus, and absorption as a function of the photometric band combinations and stellar models. We show that the historically favored three-band combinations of UBV and VRI can be meaningfully inconsistent with each other and with longer baseline data sets such as UBVRIJHK{sub S}. Differences among model sets can also be substantial. For instance, fitting Yi et al. (2001) and Dotter et al. (2008) models to UBVRIJHK{sub S} photometry for NGC 188 yields the following cluster parameters: age = (5.78 ± 0.03, 6.45 ± 0.04) Gyr, [Fe/H] = (+0.125 ± 0.003, −0.077 ± 0.003) dex, (m−M){sub V} = (11.441 ± 0.007, 11.525 ± 0.005) mag, and A{sub V} = (0.162 ± 0.003, 0.236 ± 0.003) mag, respectively. Within the formal fitting errors, these two fits are substantially and statistically different. Such differences among fits using different filters and models are a cautionary tale regarding our current ability to fit star cluster CMDs. Additional modeling of this kind, with more models and star clusters, and future Gaia parallaxes are critical for isolating and quantifying the most relevant uncertainties in stellar evolutionary models.« less

Apparent annual survival estimates of tropical songbirds better reflect life history variation when based on intensive field methods

USGS Publications Warehouse

Martin, Thomas E.; Riordan, Margaret M.; Repin, Rimi; Mouton, James C.; Blake, William M.

2017-01-01

AimAdult survival is central to theories explaining latitudinal gradients in life history strategies. Life history theory predicts higher adult survival in tropical than north temperate regions given lower fecundity and parental effort. Early studies were consistent with this prediction, but standard-effort netting studies in recent decades suggested that apparent survival rates in temperate and tropical regions strongly overlap. Such results do not fit with life history theory. Targeted marking and resighting of breeding adults yielded higher survival estimates in the tropics, but this approach is thought to overestimate survival because it does not sample social and age classes with lower survival. We compared the effect of field methods on tropical survival estimates and their relationships with life history traits.LocationSabah, Malaysian Borneo.Time period2008–2016.Major taxonPasseriformes.MethodsWe used standard-effort netting and resighted individuals of all social and age classes of 18 tropical songbird species over 8 years. We compared apparent survival estimates between these two field methods with differing analytical approaches.ResultsEstimated detection and apparent survival probabilities from standard-effort netting were similar to those from other tropical studies that used standard-effort netting. Resighting data verified that a high proportion of individuals that were never recaptured in standard-effort netting remained in the study area, and many were observed breeding. Across all analytical approaches, addition of resighting yielded substantially higher survival estimates than did standard-effort netting alone. These apparent survival estimates were higher than for temperate zone species, consistent with latitudinal differences in life histories. Moreover, apparent survival estimates from addition of resighting, but not from standard-effort netting alone, were correlated with parental effort as measured by egg temperature across species.Main conclusionsInclusion of resighting showed that standard-effort netting alone can negatively bias apparent survival estimates and obscure life history relationships across latitudes and among tropical species.

U-series ages of solitary corals from the California coast by mass spectrometry

USGS Publications Warehouse

Stein, Martin; Wasserburg, G.J.; Lajoie, K.R.; Chen, J.-H.

1991-01-01

The purpose of this study is to evaluate the feasibility of dating fossil solitary corals from Pleistocene marine strandlines outside tropical latitudes using the recently developed high sensitivity, high-precision U-series technique based on thermal-ionization mass-spectrometry (TIMS). The TIMS technique is much more efficient than conventional a spectrometry and, as a result, multiple samples of an individual coral skeleton, or different specimens from the same bed can be analyzed. Detached and well-rounded fossil specimens of the solitary coral Balanophyllia elegans were collected from relict littoral deposits on emergent marine terraces along the California coast at Cayucos terrace (elevation 8 m, previously dated at 124 and 117 Ky by ?? counting), Shell Beach terrace (elevation about 25 m, previously undated), Nestor terrace, San Diego (elevation 23 m, previously dated at 131 to 109 Ky ), Bird Rock terrace, San Diego ( elevation 8 m, previously dated at 81 Ky ). Attached living specimens were collected from the intertidal zone on the modern terrace at Moss Beach. Concentrations of 232Th in both living and fossil specimens are much higher than in reef-building corals (12 to 624 pmol/g vs. 0.1 to 1.6 pmol/g, respectively). However, because 230Th/232Th in Balanophyllia elegans are very low (2.22 ?? 10-3 to 4.33 ?? 10-4), the high 232Th concentrations have negligible effect on the 230Th-234U dates. The high 232Th concentration in the living specimen (33.1 pmol/g) indicates that a significant amount of 232Th is incorporated in the aragonitic skeleton during growth, or attached to clay-sized silicates trapped in the skeletal material. The calculated initial 234U activities in the fossil specimens of Balanophyllia elegans are higher than the 234U activity in modern seawater or in the modern specimen. The higher initial activities could possibly reflect the influx of 234U-enriched continental water into Pleistocene coastal waters, or it could reflect minor diagenetic alteration, a persistent and fundamental problem in dating all corals. Samples from a compound specimen from the Cayucos terrace were subjected to different preparation procedures. Samples prepared by a standard acid washing procedure yielded 230Th-234U ages of 125, 123, and 122 Ky, whereas samples prepared by an abbreviated procedure without acid washing yield significantly lower ages of 113 and 112 Ky. Two other specimens from the same bed yielded 230Th-234U ages of 118 and 115 Ky. Also, two specimens from a stratigraphically higher bed yielded ages of 120 and 117 Ky, and three specimens from a lower bed yield ages of 115, 113, and 101 Ky. Nine of the twelve ages of the treated samples from the Cayucos terrace range from 125 to 113 Ky. However, the ages do not follow the stratigraphie order. Two possible interpretations are ( 1 ) the age of the terrace deposit is 125 Ky and all younger ages reflect variable diagenetic alteration or (2) the age of the terrace is 125 to 113 Ky and the ages reflect sediment reworking over a period of 12 Ky. Three specimens from a single bed on the Shell Beach terrace yield ages of 126, 122, and 121 Ky, similar to the older ages from Cayucos. The ages of solitary corals from the Cayucos and Shell Beach terraces are similar to ages of reef-building corals from terraces at numerous tropical localities. These are correlated with the last interglacial sea-level highstand, which probably stood 2 to 10 m above present sea level. The youngest ages and present elevations of the Cayucos and Shell Beach terraces yield tectonic uplift rates of 0.01 and 0.15 m/Ky, respectively, assuming the original elevation of each terrace was 7 m. Four specimens from the basal gravel on the Nestor terrace yielded ages of 145, 143, 137, and 133 Ky. The three oldest ages, however, are older than that associated with the last interglacial. The possible explanations for these older ages are ( 1 ) diagenic alteration or ( 2 ) the Nestor terrace deposits reflect in s

Estimating yellow-poplar growth and yield

Treesearch

Donald E. Beck

1989-01-01

Yellow-poplar grows in essentially pure, even-aged stands, so you can make growth and yield estimates from relatively few stand characteristics. The tables and models described here require only measures of stand age, stand basal area in trees 4.5 inches and larger, and site index. They were developed by remeasuring (at 5-year intervals over a 20-year period) many...

Yield Tables and Stand Structure for Unthinned Longleaf Pine Plantations in Louisiana and Texas

Treesearch

Richard E. Longrey; Robert L. Bailey

1977-01-01

A system of equations is developed to forecast number of trees per acre, basal area, and cubic foot yields in eight volume categories by l-inch diameter classes for several combinations of site index, age from planting, and either number of trees planted, number of trees surviving, or basal area at a given age.

Dynamic programming for optimization of timber production and grazing in ponderosa pine

Treesearch

Kurt H. Riitters; J. Douglas Brodie; David W. Hann

1982-01-01

Dynamic programming procedures are presented for optimizing thinning and rotation of even-aged ponderosa pine by using the four descriptors: age, basal area, number of trees, and time since thinning. Because both timber yield and grazing yield are functions of stand density, the two outputs-forage and timber-can both be optimized. The soil expectation values for single...

20 years of intensive uneven-aged management: Effect on Growth, Yield, and Species Composition in Two hardwood Stands in West Virginia

Treesearch

George R., Jr. Trimble; George R. Trimble

1970-01-01

In 1948 a study of uneven-aged forest management, with individual tree-selection cuttings, was begun on two 31-acre stands of Appalachian hardwoods in West Virginia. Now, after 20 years, these stands are beginning to show how this kind of management affects growth, yield, and species composition.

Selected yield tables for plantations and natural stands in Inland Northwest Forests

Treesearch

Albert R. Stage; David L. Renner; Roger C. Chapman

1988-01-01

Yields arrayed by site index and age have been tabulated for plantations of 500 trees per acre, with five thinning regimes, for Douglas-fir, grand fir, and western larch. Yields were also tabulated for naturally regenerated stands of the grand fir-cedar-hemlock ecosystem of the Inland Empire. All yields were estimated with the Prognosis Model for Stand Development,...

[Dynamics of Amomum villosum growth and its fruit yield cultivated under tropical forests].

PubMed

Zheng, Zheng; Gan, Jianmin; Feng, Zhili; Meng, Ying

2004-01-01

Investigations on the dynamics of Amomum villosum growth and its fruit yield cultivated under tropical ravine rainforest and secondary forest at different elevations in Xishuangbanna showed that the yield of A. villosum was influenced by the site age, sun light level of understorey, and water stress in dry season. The fruit yield and mature plant density decreased with increasing age of the A. villosum site. The fruit yield increased with sun light level when the light level in understorey was under 35% of full sun light (P < 0.05). The fruit yield at the lower site by stream was significantly higher than that at upper site (P < 0.05). The yield difference between ravine rainforest and secondary forest was not significant. Planned cultivation of A. villosum in the secondary forest of the shifting cultivation land by ravine from 800-1000 m elevation instead of customary cultivation in the ravine rainforest, could not only resolve the problem of the effect of light deficiency in understorey and water stress in the dry season on A. villosum fruit yield, but also be useful to protect the tropical ravine rain forest.

In situ U-Th-Pb ages of the Miaoya carbonatite complex in the South Qinling orogenic belt, central China

NASA Astrophysics Data System (ADS)

Ying, Yuancan; Chen, Wei; Lu, Jue; Jiang, Shao-Yong; Yang, Yueheng

2017-10-01

The Miaoya carbonatite complex in the South Qinling orogenic belt hosts one of the largest rare earth element (REE)-Nb deposits in China that is composed of carbonatite and syenite. The emplacement age of the complex and the geochronological relationship between the carbonatite and syenite have long been debated. In this study, in situ U-Th-Pb ages have been obtained for the constituent minerals zircon, monazite and columbite from carbonatite and syenite of the Miaoya complex, together with their chemical and isotopic compositions. In situ trace element compositions for zircon from carbonatite and syenite are highly variable. The zircon displays slightly heavy REE (HREE)-enriched chondrite-normalized patterns with no Eu anomaly and various light REE (LREE) contents. In situ Th-Pb dating for zircon from the Miaoya complex by laser ablation ICP-MS yields ages of 442.6 ± 4.0 Ma (n = 53) for syenite and 426.5 ± 8.0 Ma (n = 23) for carbonatite. Monazite from carbonatite and syenite shows similar chondrite-normalized REE patterns and yields a consistent Th-Pb age of 240 Ma. Based on petrographic and chemical composition, columbite from the carbonatite can be identified into two groups. The columbite dispersed within carbonatite is characterized by slightly LREE-enriched chondrite-normalized REE patterns, whereas columbite associated with apatite is characterized by LREE-depleted trends. Columbite has been further determined to have a weighted mean 206Pb/238U age of 232.8 ± 4.5 Ma (n = 9) using LA-ICP-MS. Detailed geochronological and chemical investigations suggest that there were two major episodes of magmatic/metasomatic activities in the formational history of the Miaoya carbonatite complex. The early alkaline magmatism emplaced in the Silurian was related to the opening of the Mianlue Ocean, whereas the late metasomatism or hydrothermal overprint occurred during the Triassic South Qinling orogeny. The latter serves as the major ore formation period for both REE (e.g., monazite) and Nb (e.g., columbite).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hamrick, Mark W., E-mail: mhamrick@mail.mcg.edu; Department of Orthopaedic Surgery, Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA; Herberg, Samuel

Research highlights: {yields} Aging is associated with muscle atrophy and loss of muscle mass, known as the sarcopenia of aging. {yields} We demonstrate that age-related muscle atrophy is associated with marked changes in miRNA expression in muscle. {yields} Treating aged mice with the adipokine leptin significantly increased muscle mass and the expression of miRNAs involved in muscle repair. {yields} Recombinant leptin therapy may therefore be a novel approach for treating age-related muscle atrophy. -- Abstract: Age-associated loss of muscle mass, or sarcopenia, contributes directly to frailty and an increased risk of falls and fractures among the elderly. Aged mice andmore » elderly adults both show decreased muscle mass as well as relatively low levels of the fat-derived hormone leptin. Here we demonstrate that loss of muscle mass and myofiber size with aging in mice is associated with significant changes in the expression of specific miRNAs. Aging altered the expression of 57 miRNAs in mouse skeletal muscle, and many of these miRNAs are now reported to be associated specifically with age-related muscle atrophy. These include miR-221, previously identified in studies of myogenesis and muscle development as playing a role in the proliferation and terminal differentiation of myogenic precursors. We also treated aged mice with recombinant leptin, to determine whether leptin therapy could improve muscle mass and alter the miRNA expression profile of aging skeletal muscle. Leptin treatment significantly increased hindlimb muscle mass and extensor digitorum longus fiber size in aged mice. Furthermore, the expression of 37 miRNAs was altered in muscles of leptin-treated mice. In particular, leptin treatment increased the expression of miR-31 and miR-223, miRNAs known to be elevated during muscle regeneration and repair. These findings suggest that aging in skeletal muscle is associated with marked changes in the expression of specific miRNAs, and that nutrient-related hormones such as leptin may be able to reverse muscle atrophy and alter the expression of atrophy-related miRNAs in aging skeletal muscle.« less

Effectiveness and impact of rotavirus vaccines in Europe, 2006-2014.

PubMed

Karafillakis, Emilie; Hassounah, Sondus; Atchison, Christina

2015-04-27

Prior to the introduction of rotavirus vaccines in 2006, rotavirus was the leading cause of severe gastroenteritis among European children <5 years of age. We conducted a systematic review of the published literature to examine the effectiveness and impact of rotavirus vaccines in Europe following the first eight years of routine use. Four publication databases were searched, yielding 276 unique citations from February 1st, 2006 to July 31st, 2014. Twenty four studies on effectiveness (n=9) and impact (n=15) met the inclusion criteria. Across Europe, vaccine effectiveness against rotavirus-related healthcare utilisation ranged from 68% to 98%, consistent with efficacy data from clinical trials. Reductions in rotavirus hospitalisations ranged from 65% to 84%, consistent with findings from post-marketing studies from the US and Latin America. We confirm the significant public health benefit of rotavirus vaccination in Europe and provide further evidence to support implementation of universal rotavirus vaccination in all European countries. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Factor Structure of the Escala de Autoeficacia para la Depresión en Adolescentes (EADA)

PubMed Central

Díaz-Santos, Mirella; Cumba-Avilés, Eduardo; Bernal, Guillermo; Rivera-Medina, Carmen

2018-01-01

The current concept and measures of self-efficacy for depression in adolescents do not consider developmental and cultural aspects essential to understand and assess this construct in Latino youth. We examined the factor structure of the Escala de Autoeficacia para la Depresión en Adolescentes (EADA): a Spanish instrument designed to assess this construct as experienced by this population. Participants were 116 Puerto Rican adolescents aged 13 to 17 years who completed the EADA and two other self-report measures. An exploratory factor analysis yielded a two-factor solution (Personal Self-Efficacy for Depression and Interpersonal Self-Efficacy for Depression) accounting for 37.57% of the total variance. Results revealed that EADA factors have excellent internal consistency as well as concurrent and construct validity, supporting its adequacy to assess Latino adolescents’ self-efficacy for depression. The conceptual meaning of the factors was consistent with the distinction between aspects of this construct hypothesized to be important among Latino youth.

An elasto-visco-plastic model for immortal foams or emulsions

NASA Astrophysics Data System (ADS)

Bénito, S.; Bruneau, C.-H.; Colin, T.; Gay, C.; Molino, F.

2008-03-01

A variety of complex fluids consists in soft, round objects (foams, emulsions, assemblies of copolymer micelles or of multilamellar vesicles--also known as onions). Their dense packing induces a slight deviation from their prefered circular or spherical shape. As a frustrated assembly of interacting bodies, such a material evolves from one conformation to another through a succession of discrete, topological events driven by finite external forces. As a result, the material exhibits a finite yield threshold. The individual objects usually evolve spontaneously (colloidal diffusion, object coalescence, molecular diffusion), and the material properties under low or vanishing stress may alter with time, a phenomenon known as aging. We neglect such effects to address the simpler behaviour of (uncommon) immortal fluids: we construct a minimal, fully tensorial, rheological model, equivalent to the (scalar) Bingham model. Importantly, the model consistently describes the ability of such soft materials to deform substantially in the elastic regime (be it compressible or not) before they undergo (incompressible) plastic creep--or viscous flow under even higher stresses.

Middle Ordovician subduction of continental crust in the Scandinavian Caledonides: an example from Tjeliken, Seve Nappe Complex, Sweden

NASA Astrophysics Data System (ADS)

Fassmer, Kathrin; Klonowska, Iwona; Walczak, Katarzyna; Andersson, Barbro; Froitzheim, Nikolaus; Majka, Jarosław; Fonseca, Raúl O. C.; Münker, Carsten; Janák, Marian; Whitehouse, Martin

2017-12-01

The Seve Nappe Complex of the Scandinavian Caledonides is thought to be derived from the distal passive margin of Baltica which collided with Laurentia in the Scandian Phase of the Caledonian Orogeny at 430-400 Ma. Parts of the Seve Nappe Complex were affected by pre-Scandian high- and ultrahigh-pressure metamorphism, in a tectonic framework that is still unclear, partly due to uncertainties about the exact timing. Previous age determinations yielded between 505 and 446 Ma, with a general trend of older ages in the North (Norrbotten) than in the South (Jämtland). New age determinations were performed on eclogite and garnet-phengite gneiss at Tjeliken in northern Jämtland. Thermodynamic modelling yielded peak metamorphic conditions of 25-27 kbar/680-760 °C for the garnet-phengite gneiss, similar to published peak metamorphic conditions of the eclogite (25-26 kbar/650-700 °C). Metamorphic rims of zircons from the garnet-phengite gneiss were dated using secondary ion mass spectrometry and yielded a concordia age of 458.9 ± 2.5 Ma. Lu-Hf garnet-whole rock dating yielded 458 ± 1.0 Ma for the eclogite. Garnet in the eclogite shows prograde major-element zoning and concentration of Lu in the cores, indicating that this age is related to garnet growth during pressure increase, i.e. subduction. The identical ages from both rock types, coinciding with published Sm-Nd ages from the eclogite, confirm subduction of the Seve Nappe Complex in Northern Jämtland during the Middle Ordovician in a fast subduction-exhumation cycle.

Comparative thermometry on pelitic rocks and marbles of the Llano uplift, Texas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Letargo, C.M.R.; Lamb, W.M.

1992-01-01

The Llano Uplift in central Texas is a Grenville-aged metamorphic complex consisting of amphibolite facies assemblages whose development has been attributed to the emplacement of granite plutons between 1.0--1.1 Ga. Temperatures have been obtained from garnet-biotite, garnet-ilmenite, and calcite-dolomite pairs as well as from various silicate equilibria. Application of these geothermometers yield consistent results and are thus indicative of peak conditions attending the amphibolite facies metamorphism. Temperature determined using garnet-biotite and garnet-ilmenite thermometry compare favorably with calcite-dolomite temperatures obtained from marbles in contact with granite plutons in the southeastern part of the uplift. The highest calcite-dolomite temperatures of [approximately]600 Cmore » are obtained from marbles containing an isobarically invariant assemblage consisting of calcite + dolomite + diopside + tremolite + forsterite. At pressures of 2--3 kbar, this isobarically invariant assemblage will be stable at a temperature range of [approximately]600--650 C. Also in close proximity to granites in the southeast uplift is the assemblage muscovite + quartz + k-feldspar + sillimanite [approximately] andalusite which indicate T 650 C and P 2.5 kbar. Assemblages consisting of garnet + sillimanite + quartz + plagioclase (GASP) and garnet + rutile + ilmenite + plagioclase + quartz (GRIPS) are currently being studied to provide additional constraints on pressures of amphibolite facies metamorphism.« less

Selective Mutism Questionnaire: measurement structure and validity.

PubMed

Letamendi, Andrea M; Chavira, Denise A; Hitchcock, Carla A; Roesch, Scott C; Shipon-Blum, Elisa; Stein, Murray B

2008-10-01

To evaluate the factor structure, reliability, and validity of the 17-item Selective Mutism Questionnaire (SMQ). Diagnostic interviews were administered via telephone to 102 parents of children identified with selective mutism (SM) and 43 parents of children without SM from varying U.S. geographic regions. Children were between the ages of 3 and 11 inclusive and comprised 58% girls and 42% boys. SM diagnoses were determined using the Anxiety Disorders Interview Schedule for Children-Parent Version; SM severity was assessed using the 17-item SMQ; and behavioral and affective symptoms were assessed using the Child Behavior Checklist. An exploratory factor analysis was conducted to investigate the dimensionality of the SMQ and a modified parallel analysis procedure was used to confirm exploratory factor analysis results. Internal consistency, construct validity, and incremental validity were also examined. The exploratory factor analysis yielded a 13-item solution consisting of three factors: social situations outside of school, school situations, and home and family situations. Internal consistency of SMQ factors and total scale ranged from moderate to high. Convergent and incremental validity was also well supported. Measure structure findings are consistent with the three-factor solution found in a previous psychometric evaluation of the SMQ. Results also suggest that the SMQ provides useful and unique information in the prediction of SM phenomena beyond other child anxiety measures.

40Ar/ 39Ar and paleomagnetic results from Liberia and the Precambrian APW data base for the West African Shield

NASA Astrophysics Data System (ADS)

Onstott, T. C.; Dorbor, J.

Lower amphibolite to granulite facies metamorphic rocks in Nimba County, Liberia have yielded 2.2-2.9 Ga RbSr whole rock ages, indicating that they are part of the Archean Liberian age province. We report a 2040 Ma 4040Ar/ 39Ar plateau date on hornblende from an amphibolite in this region, and suggest that these rocks were also severelyreworked during the Eburnean (˜2.0 Ga) metamorphic episode. 40Ar/ 39Ar analyses of biotite and feldspars from neighboring schists also indicate the presence of two mild thermal events, at 1.5 Ga and 0.6 Ga. Paleomagnetic analyses of samples from these same metamorphic rocks reveal three components of magnetization. The predominant and most stable component (273°E, 21°N) is considered to have been acquired as a result of pos Eburnean uplift and cooling at ˜ 2.0 Ga, whereas the two less stable components with poles at 235°E, 43°N and 16°E, 36°N, probably correlate with the 1.5 Ga and 0.6 Ga thermal pulses, respectively. Rock units from southern Liberia also yield two secondary magnetizations, one at 247°E, 37°N and the other at 104°E, 5°N, and a 1.5 Ga 40Ar/ 39Ar date on plagioclase. Comparison of the paleomagnetic poles corresponding to the ˜2.0 Ga Eburnean component with published paleomagnetic data for West Africa is not consistent with prior interpretations of the polar wander path for West Africa. Our paleomagnetic data, when compared to poles of comparable age from the Kalahari Shield, still suggest that some form of displacement has occurred between the Kalahari and West African Shields since 2.0 Ga.

Assessment of proximal pulmonary arterial stiffness using magnetic resonance imaging: effects of technique, age and exercise

PubMed Central

Kamalasanan, Anu; Cassidy, Deidre B; Struthers, Allan D; Lipworth, Brian J; Houston, J Graeme

2016-01-01

Introduction To compare the reproducibility of pulmonary pulse wave velocity (PWV) techniques, and the effects of age and exercise on these. Methods 10 young healthy volunteers (YHV) and 20 older healthy volunteers (OHV) with no cardiac or lung condition were recruited. High temporal resolution phase contrast sequences were performed through the main pulmonary arteries (MPAs), right pulmonary arteries (RPAs) and left pulmonary arteries (LPAs), while high spatial resolution sequences were obtained through the MPA. YHV underwent 2 MRIs 6 months apart with the sequences repeated during exercise. OHV underwent an MRI scan with on-table repetition. PWV was calculated using the transit time (TT) and flow area techniques (QA). 3 methods for calculating QA PWV were compared. Results PWV did not differ between the two age groups (YHV 2.4±0.3/ms, OHV 2.9±0.2/ms, p=0.1). Using a high temporal resolution sequence through the RPA using the QA accounting for wave reflections yielded consistently better within-scan, interscan, intraobserver and interobserver reproducibility. Exercise did not result in a change in either TT PWV (mean (95% CI) of the differences: −0.42 (−1.2 to 0.4), p=0.24) or QA PWV (mean (95% CI) of the differences: 0.10 (−0.5 to 0.9), p=0.49) despite a significant rise in heart rate (65±2 to 87±3, p<0.0001), blood pressure (113/68 to 130/84, p<0.0001) and cardiac output (5.4±0.4 to 6.7±0.6 L/min, p=0.004). Conclusions QA PWV performed through the RPA using a high temporal resolution sequence accounting for wave reflections yields the most reproducible measurements of pulmonary PWV. PMID:27843548

Age and tectonic setting of the Mesozoic McCoy Mountains Formation in western Arizona, USA

USGS Publications Warehouse

Spencer, J.E.; Richard, S.M.; Gehrels, G.E.; Gleason, J.D.; Dickinson, W.R.

2011-01-01

The McCoy Mountains Formation consists of Upper Jurassic to Upper Cretaceous siltstone, sandstone, and conglomerate exposed in an east-west-trending belt in southwestern Arizona and southeastern California. At least three different tectonic settings have been proposed for McCoy deposition, and multiple tectonic settings are likely over the ~80 m.y. age range of deposition. U-Pb isotopic analysis of 396 zircon sand grains from at or near the top of McCoy sections in the southern Little Harquahala, Granite Wash, New Water, and southern Plomosa Mountains, all in western Arizona, identifi ed only Jurassic or older zircons. A basaltic lava fl ow near the top of the section in the New Water Mountains yielded a U-Pb zircon date of 154.4 ?? 2.1 Ma. Geochemically similar lava fl ows and sills in the Granite Wash and southern Plomosa Mountains are inferred to be approximately the same age. We interpret these new analyses to indicate that Mesozoic clastic strata in these areas are Upper Jurassic and are broadly correlative with the lowermost McCoy Mountains Formation in the Dome Rock, McCoy, and Palen Mountains farther west. Six samples of numerous Upper Jurassic basaltic sills and lava fl ows in the McCoy Mountains Formation in the Granite Wash, New Water, and southern Plomosa Mountains yielded initial ??Nd values (at t = 150 Ma) of between +4 and +6. The geochemistry and geochronology of this igneous suite, and detrital-zircon geochronology of the sandstones, support the interpretation that the lower McCoy Mountains Formation was deposited during rifting within the western extension of the Sabinas-Chihuahua-Bisbee rift belt. Abundant 190-240 Ma zircon sand grains were derived from nearby, unidentifi ed Triassic magmatic-arc rocks in areas that were unaffected by younger Jurassic magmatism. A sandstone from the upper McCoy Mountains Formation in the Dome Rock Mountains (Arizona) yielded numerous 80-108 Ma zircon grains and almost no 190-240 Ma grains, revealing a major reorganization in sediment-dispersal pathways and/or modifi cation of source rocks that had occurred by ca. 80 Ma. ?? 2011 Geological Society of America.

Zircon U-Pb ages and Sr-Nd-Hf isotopes of the highly fractionated granite with tetrad REE patterns in the Shamai tungsten deposit in eastern Inner Mongolia, China: Implications for the timing of mineralization and ore genesis

NASA Astrophysics Data System (ADS)

Jiang, Si-Hong; Bagas, Leon; Hu, Peng; Han, Ning; Chen, Chun-Liang; Liu, Yuan; Kang, Huan

2016-09-01

The Shamai tungsten deposit is located in the eastern part of the Central Asian Orogenic Belt (CAOB). Tungsten mineralization is closely related to the emplacement of fine- to medium-grained biotite monzogranite (G1) and porphyritic biotite monzogranite (G2) in the Shamai Granite. NW-trending joints and faults host orebodies in the Shamai Granite and Devonian hornfels. The mineralization is characterized by a basal veinlet zone progressing upwards to a thick vein zone followed by a mixed zone, a veinlet zone, and a thread vein zone at the top. The ore-related alteration typically consists of muscovite, greisen, and hornfels. In order to constrain the timing of the Shamai mineralization and discuss the ore genesis, muscovite Ar-Ar, molybdenite Re-Os, and zircon U-Pb geochronological, geochemical, and Sr-Nd-Hf isotopic studies were completed on the deposit. The U-Pb zircon dating yielded weighted mean ages of 153 ± 1 Ma for G1 and 146 ± 1 Ma for G2. Muscovite from a wolframite-bearing quartz vein yielded an Ar-Ar plateau age of 140 ± 1 Ma, whereas two molybdenite samples yielded identical Re-Os model ages of 137 ± 2 Ma. These two ages are younger than the two monzogranites, suggesting a prolonged magmatic-hydrothermal interaction during tungsten mineralization. Major and trace element geochemistry shows that both G1 and G2 are characterized by high SiO2 and K2O contents, high A/CNK values (1.08-1.40), a spectacular tetrad effect in their REE distribution patterns, and non-CHARAC (charge-and-radius-controlled) trace element behavior. This suggests that both G1 and G2 are highly differentiated peraluminous rocks with strong hydrothermal interaction. The Nd-Hf isotope data for the Shamai Granite (εNd(t) between - 1.9 and + 7.4, ɛHf(t) from 5.2 to 12.8) are largely compatible with the general scenario for much of the Phanerozoic granite emplaced in the CAOB. It is here suggested that the Shamai Granite originated from partial melting of a juvenile lower crust with minor input of upper crustal material caused by the underplating of mafic magma in an extensional setting. It can also be concluded that the prolonged fractional crystallization and magmatic-hydrothermal interactions have contributed to the formation of the Shamai tungsten deposit.

Lu-Hf Garnet Geochronology Reveals the Tectonic History of Precambrian Rocks in the Southern Rocky Mountains

NASA Astrophysics Data System (ADS)

Aronoff, R.; Andronicos, C.; Vervoort, J. D.; Hunter, R. A.

2014-12-01

Lu-Hf garnet dating of Proterozoic rocks of the southwestern United States provides constraints on the timing and geographic extent of metamorphism associated with the Yavapai, Mazatzal, and newly recognized Picuris orogenies. Prior work focusing on U-Pb dating of plutons and Ar geochronology has left the timing of prograde metamorphism ambiguous, particularly in northern New Mexico and southern Colorado. Because the Lu-Hf system dates the onset of garnet growth, it can constrain the timing of the prograde P-T path. Garnet schist samples from central and northern New Mexico exhibit garnet growth restricted to the time period between ~1460 and 1400 Ma. In the Picuris and Manzano mountains, the oldest Lu-Hf garnet ages predate the U-Pb ages of ~1.4 Ga plutons located near the dated samples. This implies that garnet growth, and therefore the onset of amphibolite facies metamorphism, cannot be driven by contact metamorphism, as has been previously inferred. Garnet-bearing samples from the Needle and Wet Mountains in southern Colorado display a range of garnet ages between ~1750 and 1470 Ma. A garnet gneiss from the Needle Mountains in southwestern Colorado yields an age of 1748 Ma, which is consistent with the Yavapai orogeny. This Lu-Hf garnet age has not been reset by contact metamorphism associated with the emplacement of the ~1.4 Ga Eolus batholith. Anatectic garnet in an orthogneiss from the northern Wet Mountains yields an age of 1601 Ma and is interpreted to date partial melting at the close of the Mazatzal orogeny. A 1476 Ma garnet age from the aureole of the 1440 Ma Oak Creek pluton is interpreted to date upper amphibolite facies metamorphism. The age distribution of these samples shows that rocks in Colorado underwent a complex, poly-metamorphic history, while rocks in New Mexico underwent a single progressive metamorphic event. This contrast implies that the boundary between rocks deformed and metamorphosed during the ~1800-1600 Ma Yavapai and Mazatzal orogenies and those only deformed and metamorphosed during the ~1460-1400 Ma Picuris orogeny lies in northern New Mexico, along what has previously been considered the Mazatzal front. By using Lu-Hf geochronology to directly date a rock-forming mineral, we are better able to reconstruct the tectonic history of this region.

Geochronological framework of the early Paleozoic Bainaimiao Cu-Mo-Au deposit, NE China, and its tectonic implications

NASA Astrophysics Data System (ADS)

Zhou, Zhen-Hua; Mao, Jing-Wen; Ma, Xing-Hua; Che, He-Wei; Ou'yang, He-Gen; Gao, Xu

2017-08-01

The Bainaimiao Cu-Mo-Au deposit of NE China is an important ore deposit in the middle section of the northern margin of the North China Craton. The early Paleozoic Bainaimiao Group is the main ore-hosting rock. The mineralization at the deposit shows features of porphyry alteration and late-stage orogenesis and transformation. Zircon LA-ICP-MS U-Pb age data indicate that the ages of the Third and Fifth formations of the Bainaimiao Group are 492.7 ± 2.9 Ma (MSWD = 0.53) and 488.9 ± 3.1 Ma (MSWD = 0.92), respectively. The age of quartz diorite that intrudes the Bainaimiao Group is 459.3 ± 6.4 Ma (MSWD = 2.20). Molybdenite samples from massive Cu-Mo-bearing ores and quartz veins in the southern ore belt yield a Re-Os isochron age of 438.2 ± 2.7 Ma (MSWD = 0.16), which is consistent with the Re-Os isochron age of molybdenite in the northern ore belt, implying that the two ore belts belong to the same mineralization system. Muscovite from a post-magmatic Cu-Mo-bearing quartz-calcite vein yields an Ar-Ar isochron age of 422.5 ± 3.9 Ma (MSWD = 0.64) with an initial 40Ar/36Ar ratio of 286 ± 21. The well-defined plateau age of the muscovite is 422.4 ± 2.6 Ma (MSWD = 0.05), which represents the time of the post-magmatic orogenic transformation event. Based on our new age data and previous findings, we propose that the Bainaimiao Cu-Mo-Au deposit formed in an active continental margin setting and experienced four stages of ore mineralization: (1) a Late Cambrian-Middle Ordovician volcanic-sedimentary stage; (2) a Late Ordovician porphyry mineralization stage; (3) a Late Silurian regional metamorphism stage; and (4) an orogenic transformation stage. Subhedral and euhedral Paleoproterozoic (2402-1810 Ma) inherited zircons indicate that the Bainaimiao Group has a tectonic affinity with the North China Craton. The Central Asian Orogenic Belt, which is closely related to the complex closure of the Paleo-Asian Ocean, is favorable for prospecting for Paleozoic porphyry Cu-Mo or Cu-Au mineralization and associated epithermal Au deposits.

Lipoabdominoplasty: An exponential advantage for a consistently safe and aesthetic outcome.

PubMed

Kanjoor, J R; Singh, A K

2012-01-01

Extensive liposuction along with limited dissection of abdominal flaps is slowly emerging as a well proven advantageous method over standard abdominoplasty. A retrospective study analyzed 146 patients managed for the abdominal contour deformities from March 2004 to February 2010. A simple method to project the post operative outcome by rotation of a supine lateral photograph to upright posture in 46 patients prospectively has succeeded in projecting a predictable result. All patients were encouraged to practice chest physiotherapy in 'tummy tuck' position during the preoperative counseling. Aggressive liposuction of entire upper abdomen, a limited dissection in the midline, plication of diastasis of rectus whenever indicated, panniculectomy and neoumblicoplasty were done in all patients. The patients had a mean age of 43, youngest being 29 and oldest 72 years. Majority were of normal weight (94%). Twelve were morbidly obese; 57 patients had undergone previous abdominal surgeries; 49 patients had associated hernias. Lipoabdominoplasty yielded a satisfactory result in 110 (94%) patients. The postoperative patient had a definitely less heavy harmonious abdomen with improved waistline. The complications were more with higher BMI, fat thickness of more than 7 cm and prolonged operating time when other procedures were combined. Extensive liposuction combined with limited dissection method applied to all abdominoplasty patients yielded consistently safe, reliable and predictable aesthetic results with less complications and faster recovery. The simple photographic manipulation has helped project the postoperative outcome reliably. The preoperative chest physiotherapy in tummytuck position helped prevent chest complications.

Paleomagnetic results from Tertiary volcanic strata and intrusions, Absaroka Volcanic Supergroup, Yellowstone National Park and vicinity: Contributions to the North American apparent polar wander path

USGS Publications Warehouse

Harlan, S.S.; Morgan, L.A.

2010-01-01

We report paleomagnetic and rock magnetic data from volcanic, volcaniclastic, and intrusive rocks of the 55-44Ma Absaroka Volcanic Supergroup (AVS) exposed along the northeastern margin of Yellowstone National Park and adjacent areas. Demagnetization behavior and rock magnetic experiments indicate that the remanence in most samples is carried by low-Ti titanomagnetite, although high-coercivity phases are present in oxidized basalt flows. Paleomagnetic demagnetization and rock magnetic characteristics, the presence of normal and reverse polarity sites, consistency with previous results, and positive conglomerate tests suggest that the observed remanences are primary thermoremanent magnetizations of Eocene age (c. 50Ma). An in situ grand-mean for 22 individual site- or cooling-unit means from this study that yield acceptable data combined with published data from Independence volcano yields a declination of 347.6?? and inclination of 59.2?? (k=21.8, ??95=6.8??) and a positive reversal test. Averaging 21 virtual geomagnetic poles (VGPs) that are well-grouped yields a mean at 137.1??E, 82.5??N (K=17.6, A95=7.8??), similar to results previously obtained from published studies from the AVS. Combining the VGPs from our study with published data yields a combined AVS pole at 146.3??E, 83.1??N (K=13.5, A95=6.2??, N=42 VGPs). Both poles are indistinguishable from c. 50Ma cratonic and synthetic reference poles for North America, and demonstrate the relative stability of this part of the Cordillera with respect to the craton. ?? 2009 Elsevier B.V.

On the age of sinistral shearing along the southern border of the Tauern Window (Eastern Alps).

NASA Astrophysics Data System (ADS)

Kitzig, C.; Schneider, S.; Hammerschmidt, K.

2009-04-01

The first-order structure of the western Tauern Window consists of three upright, ENE-striking antiforms of large amplitude, whose flanks are overprinted by sinistral shear zones, striking parallel to the axial planes of the antiforms. Analogue modelling suggests that these shear zones accommodate part of the shortening of the South Alpine indenter (Rosenberg et al., 2004). The age of sinistral shearing in the western Tauern Window and immediately south of it is still controversial. Mancktelow et al. (2001) suggested that sinistral shearing at the southern border of the Tauern Window terminated at 30 Ma. Based on monazite spot dates ranging between 29.0-20.3 Ma (n=10) of dextral shear zones, which cross-cut the sinistral Greiner shear zone, Barnes et al. (2004) argued that the switch from sinistral to dextral shear occurred shortly after the thermal peak of the Alpine orogeny (c.~ 30 Ma). Recent dating of mica-bearing marble suggested that the activity of the southernmost sinistral shear zone of the Tauern Window (the Ahrntal shear zone) was 19.8±0.4 Ma ago (Glodny et al. 2008). Sinistral shearing is commonly interpreted as part of the 2nd Alpine phase of deformation that affected the Tauern Window. The main foliation (S1) of the Tauern Window was acquired during a first phase, which resulted in the present day nappe stack. Only along some of the later shear zones a second Alpine foliation (S2) was formed. At present no attempt has been made, to distinguish the two and directly date the S2 mylonitic foliation. In the present work we use the Rb/Sr method to date mineral pairs formed under greenschist to lower amphibolite facies conditions from the tonalitic Zentral Gneiss. We dated four samples, two from the inferred undeformed tonalite protolith, one from the strongly foliated tonalitic gneiss and one from an outcrop-scale sinistral shear zone within the foliated tonalitic gneiss. Generally biotite and feldspar define isochrones for the four samples. The undeformed tonalites yield an age of 26.4±0.1 Ma and of 11.1±0.1 Ma, the strongly foliated tonalitic gneiss yields an age of 19.8±0.1 Ma, which is close to the age of the outcrop-scale shear zone of 18.0±0.1 Ma. It is difficult to interpret the 11 Ma age of one undeformed sample, because it is significantly younger than the ages obtained from zircon fission tracks from neighbouring areas. The older age of 26 Ma for the undeformed tonalite sample is interpreted as cooling age below the closure temperature of biotite, based on the following arguments: 1) This age is consistent with the inferred regional thermochronological distribution of cooling (Luth and Willingshofer, 2008); 2) The rock fabric is undeformed; 3) The age is older than the two deformed samples collected within a distance of a few hundreds of meters. The mineral assemblage of the deformed samples (green biotite and albite crystallisation) differs from the one of the undeformed rocks (red-brown biotite and K-feldspar clasts). Therefore, the albite-biotite isochrons of the deformed samples are inferred to date the deformation event. This age of deformation is consistent with the age determination of Glodny et al. (2008) from deformed marbles of the Schieferhülle, and with previous dating of sinistral shearing along the northern border of the western Tauern Window (Schneider et al., 2007), which yielded an average (n=5) age of 21.9±1.6 Ma. Therefore, sinistral deformation appears to have affected contemporaneously both the northern and the southern margins of the Zentral Gneiss in the western Tauern Window. References: Barnes, J. D., Selverstone, J. & Sharp, Z.D., 2004. Interactions between serpentinite devolatilization, metasomatism and strike-slip strain localization during deep-crustal shearing in the Eastern Alps. Journal of Metamorphic Geology, 22, 283-300. Glodny, J., Ring, U. Kühn. A., 2008. Coeval high-pressure metamorphism, thrusting, strike slip, and extensional shearing in the Tauern Window, Eastern Alps, Tectonics, 27, TC4004, DOI:10.1029/2007TC002193. Luth, S.W., & Willingshofer, E. 2008. Mapping of the Post-Collisional Cooling History of the Eastern Alps, Birkhäuser Verlag, Basel DOI:10.1007/s00015-008-1294-9 Mancktelow, N.S., Stöckli, D., Grollimund, B., Müller, W., Fügenschuh, B., Viola, G., Seward, D. & Villa, I., 2001. The DAV and Periadriatic fault systems in the eastern Alps south of the Tauern Window. International Journal of Earth Sciences, 90, 593-622. Rosenberg, C.L., Brun, J.-P., Cagnard, F., and Gapais, D., 2007. Oblique indentation in the Eastern Alps: Insights from laboratory experiments, Tectonics, 26, TC2003, doi:10.1029/2006TC001960. Schneider, S., Hammerschmidt, K., and Rosenberg, C.L., 2007. In-situ Rb-Sr dating of the SEMP mylonites, western Tauern Window, Eastern Alps Geophysical Research Abstracts, Vol. 9, 09136. SRef-ID: 1607-7962/gra/EGU2007-A-09136

Characterization of different biological types of steers (cycle IV): wholesale, subprimal, and retail product yields.

PubMed

Wheeler, T L; Cundiff, L V; Koch, R M; Dikeman, M E; Crouse, J D

1997-09-01

Carcass cut-out yields of 888 steers obtained from mating Hereford and Angus cows to Hereford or Angus (HA), Charolais (Ch), Gelbvieh (Gb), Pinzgauer (Pz), Shorthorn (Sh), Galloway (Gw), Longhorn (Lh), Nellore (Ne), Piedmontese (Pm), and Salers (Sa) sires were compared. Data were evaluated at constant age (426 d), carcass weight (324 kg), fat thickness (1.2 cm), fat trim percentage (23%), and marbling (Small(00)) end points. Piedmontese-sired steers excelled in total retail product and fat trim percentages at all slaughter end points except at the 23% fat trim end point. At an age end point, percentage of retail product was greater in steers sired by Continental European breeds (Gb, Ch, Sa, Pz; 63.3 to 65.5% at 0 cm trim) than in steers sired by British breeds (Sh, HA; 60.1 to 61.0%). Piedmontese-sired steers, which were expected to carry one copy of a major gene for muscle hypertrophy, had the highest (P < .05) retail product yields at an age end point (69.7%). At an age end point, although carcass weights were significantly heavier (P < .05) for Charolais-sired steers than for Piedmontese-sired steers, lean growth rate, as reflected by totally trimmed retail product at 426 d, was similar (P > .05) for Piedmontese and Charolais-sired steers. Differences among sire breeds were small for retail product percentage at marbling, fat thickness, and fat trim end points. Ranking of sire breeds for age-constant weight of retail product was as follows: Ch, Pm, Gb, Sa, Ne, Pz, HA, Sh, Gw, and Lh. Sire breed differences in wholesale and subprimal cut yields were similar to total retail product differences. Piedmontese-sired steers produced the most muscular, leanest, and highest-yielding carcasses, and HA- and Sh-sired steers produced the fattest, lowest-yielding carcasses.

Evolution of the Jan Mayen Ridge - new geochemical and geophysical data from the Jan Mayen Fracture Zone

NASA Astrophysics Data System (ADS)

Slama, J.; Pedersen, R. B.; Kosler, J.; Kandilarov, A.; Hendriks, B. W. H.

2009-04-01

Geochronologic and geochemical data derived from sea-floor samples dredged from the Jan Mayen Fracture Zone together with seismic data provide new insight into the tectonomagmatic evolution of the Jan Mayen Ridge. Based on the seismic data, the Jan Mayen Ridge is believed to represent an off-rifted fragment of East Greenland continental lithosphere that since early Miocene has drifted 400 km into the North Atlantic as a result of sea-floor spreading along the Kolbeinsey Ridge. At present the Jan Mayen Ridge is uniquely located at the Mid-Atlantic Ridge north of Iceland. During the recent G.O.SARS research cruises a suite of volcanic rocks, as well as sandstones and conglomerates that are predominantly made up of volcaniclastic material were recovered from the southern escarpment of Jan Mayen Fracture Zone east of Jan Mayen. The conglomerates contain carbonate shell fragments that yielded 87Sr/86Sr age of ca. 32 Ma, which probably reflects the time of deposition of these volcano-sedimentary rocks. U-Pb ages of detrital zircon from the samples show age distribution consistent with an East Greenland source region characterized by a wide age pattern with significant Archaean and Early Proterozoic component. A population of angular zircons provides the youngest ages around 30 Ma, which are consistent with the Sr-age data from the shell fragment. These young zircons are most likely derived from the local volcanic material and do accordingly date the volcanic activity. Chemical analyses of individual volcanic clasts in the conglomerates show that they belong to the trachytic suite, and correspond mainly to hawaiites and trachyandesites. They are geochemically very similar to the recent volcanic rocks of the Jan Mayen Island. The maximum age of some of the volcanic clasts obtained by Ar-Ar whole-rock dating is consistent with the age of the youngest detrital zircons and with the Sr-age of the shell fragment. The new data suggest that the alkaline volcanism in the Jan Mayen area may be traced 30 My back in time. It is yet unknown however, whether or not the volcanic activity has been continuous since that time. The lack of a significant crustal contamination of the volcanic rocks of the Jan Mayen Ridge and in the Jan Mayen Fracture Zone is consistent with the results of seismic survey that suggests an existence of continental lithosphere beneath the northern part of the Jan Mayen Ridge farther south of the Jan Mayen Fracture Zone, i.e. farther from the volcanic center. Geophysical data suggest that spreading along the Kolbeinsey Ridge started ca. 25 My ago. The ca. 30 Ma magmatic event recorded in the dredged samples from the Jan Mayen Fracture Zone seems to reflect an episode of alkaline break-up magmatism associated with the off-rifting of the Jan Mayen micro-continent.

Yield of Unthinned Yellow-Poplar

Treesearch

Donald E. Beck; Lino Della-Bianca

1970-01-01

Cubic-foot and board-foot yields of unthinned yellow-poplar (Liriodendron Tulipiferi L.) stands are described in relation to stand age, site index, and number of trees per acre. The yield tables are based on analysis of diameter distributions and height-diameter relationships obtained from 141 natural, unthinned yellow-poplar stands in the...

Crystallisation ages in coeval silicic magma bodies: 238U-230Th disequilibrium evidence from the Rotoiti and earthquake flat eruption deposits, Taupo volcanic zone, New Zealand

USGS Publications Warehouse

Charlier, B.L.A.; Peate, D.W.; Wilson, C.J.N.; Lowenstern, J. B.; Storey, M.; Brown, S.J.A.

2003-01-01

The timescales over which moderate to large bodies of silicic magma are generated and stored are addressed here by studies of two geographically adjacent, successive eruption deposits in the Taupo Volcanic Zone, New Zealand. The earlier, caldera-forming Rotoiti eruption (>100 km3 magma) at Okataina volcano was followed, within months at most, by the Earthquake Flat eruption (??? 10 km3 magma) from nearby Kapenga volcano; both generated nonwelded ignimbrite and coeval widespread fall deposits. The Rotoiti and Earthquake Flat deposits are both crystal-rich high-silica rhyolites, with sparse glass-bearing granitoid fragments also occurring in Rotoiti lag breccias generated during caldera collapse. Here we report 238U-230Th disequilibrium data on whole rocks and mineral separates from representative Rotoiti and Earthquake Flat pumices and the co-eruptive Rotoiti granitoid fragments using TIMS and in situ zircon analyses by SIMS. Multiple-grain zircon-controlled crystallisation ages measured by TIMS from the Rotoiti pumice range from 69??3 ka ( 350 ka, with a pronounced peak at 70-90 ka. The weighted mean of isochrons is 83??14 ka, in accord with the TIMS data. One glass-bearing Rotoiti granitoid clast yielded an age of 57??8 ka by TIMS (controlled by Th-rich phases that, however, are not apparently present in the juvenile pumices). Another glass-bearing Rotoiti granitoid yielded SIMS zircon model ages peaking at 60-90 ka, having a similar age distribution to the pumice. Age data from pumices are consistent with a published 64??4 ka eruptive age (now modified to 62??2 ka), but chemical and/or mineralogical data imply that the granitoid lithics are not largely crystalline Rotoiti rhyolite, but instead represent contemporaneous partly molten intrusions reflecting different sources in their chemistries and mineralogies. Similarly, although the Earthquake Flat eruption immediately followed (and probably was triggered by) the Rotoiti event, age data from juvenile material are significantly different. A multiple-grain zircon-controlled crystallisation age measured by TIMS from a representative pumice is 173??5 ka, while SIMS model ages range from 70-26+34 ka to >350 ka, with a peak at 105 ka. These age data coupled with previously published geochemical and isotopic data show that the Rotoiti and Earthquake Flat deposits were erupted from independent, unconnected magma bodies. Published by Elsevier Science B.V.

Gross yield and mortality tables for fully stocked stands of Douglas-fir.

Treesearch

George R. Staebler

1955-01-01

Increasing interest in the practice of intensive forestry has demonstrated the need for gross yield tables for Douglas-fir showing the volume of trees that die as well as volume of live trees. Net yield tables for Douglas-fir, published in 1930, give the live volume in fully stocked stands at different ages on different sites. As in all normal yield tables, no...

Evidence for large-scale submarine mass wasting associated with growth of oceanic core complexes, 16°N, Mid-Atlantic Ridge.

NASA Astrophysics Data System (ADS)

Urann, B.; Cheadle, M. J.; John, B. E.; Dick, H. J.

2016-12-01

Slow spreading ridges display distinct geomorphologic features, often interpreted as long-lived detachment faults, where mafic and ultramafic rocks are exposed at the seafloor. Many bathymetric features in these regions are viewed as the result of tectonic processes (long lived detachment faults), however other features are clearly the result of mass wasting. Here we report zircon U-Pb dates from four gabbro and Fe-Ti oxide gabbro dredge samples recovered from the North Segment on the western flank of the mid-Atlantic ridge (MAR) at 16°N. Initial SIMS U-Pb zircon dating using the Stanford-USGS SHRIMP-RG ion-microprobe yield 230 Th-corrected zircon 206Pb/238U dates within error of one another. The two westernmost samples are separated by 14km along strike, and come from dredges on the footwall of a high-angle normal fault. They have dates of 1.112 +/-0.083 Ma and 1.181 +/- 0.074Ma, and both lie 12-13km west of the present day axial volcanic ridge, These samples therefore yield a spreading rate of 12km/Ma, as expected for this part of the MAR. The two eastern samples lie up to 4.5 km east of the western samples and yield dates of 1.14_/-0.55Ma and 1,221+/-0.027Ma, indistinguishable from those of the samples to the west. Given the predicted spreading rate of 12 km/Ma, these samples should be 0.375Ma younger than those to the west, and should yield dates of 0.74Ma. To account for the similarity in age, we suggest that mass wasting and large landslides from the high angle fault scarps displaced as much as 40km3 of material into the axial valley, dispersing gabbro of similar age over a wide area. This interpretation is consistent with the available multi-beam bathymetry that can be explained in terms of large landslides flowing from the bounding fault scarps into the axial valley towards the present day axial volcanic ridge. If correct, this interpretation has significant implications for evaluating potential tsunami hazards at mid-ocean ridges.

Performance, meat quality, and pectoral myopathies of broilers fed either corn or sorghum based diets supplemented with guanidinoacetic acid.

PubMed

Córdova-Noboa, H A; Oviedo-Rondón, E O; Sarsour, A H; Barnes, J; Ferzola, P; Rademacher-Heilshorn, M; Braun, U

2018-04-13

One experiment was conducted to evaluate the effects of guanidinoacetic acid (GAA) supplementation in broilers fed corn or sorghum-based diets on live performance, carcass and cut up yields, meat quality, and pectoral myopathies. The treatments consisted of corn or sorghum-based diets with or without the addition of GAA (600 g/ton). A total of 800 one-d-old male Ross 708 broiler chicks were randomly placed in 40 floor pens with 10 replicates (20 birds per pen) per each of the four treatments. At hatch, 14, 35, and 50 d, BW and feed intake were recorded. BW gain and FCR were calculated at the end of each phase. Four broilers per pen were selected and slaughtered at 51d and 55d of age to determine carcass and cut up yields, meat quality and myopathies (spaghetti muscle, white striping, and wooden breast) severity in the Pectoralis major. Data were analyzed as a randomized complete block design in a 2 × 2 factorial arrangement with grain type and GAA supplementation as main effects. At 50 d, diets containing GAA improved (P < 0.01) FCR (1.682 vs. 1.724 g: g) independently of grain type. At 55 d, broilers fed corn diets with GAA had higher breast meat yield (P < 0.05) compared to corn without GAA. Drip and cook loss, and shear force (Warner-Bratzler) were not affected (P > 0.05) by GAA supplementation at any slaughter ages. However, GAA decreased (P < 0.05) the ultimate pH at 51 and 55 d in breast meat samples compared to unsupplemented diets. At 51 d, broilers supplemented with GAA had double (P < 0.05) breast meat fillets without wooden breast (score 1) compared with broilers fed non-supplemented diets, therefore reducing the severity of this myopathy. In conclusion, GAA supplementation improved broiler live performance in broilers raised up to 50 d independently of grain source, increased breast meat yield in corn-based diets and reduced the severity of wooden breast myopathy.

Iodine-xenon studies of Bjurbole and Parnallee using RELAX

NASA Astrophysics Data System (ADS)

Gilmour, J. D.; Ash, R. D.; Hutchison, R.; Bridges, J. C.; Lyon, I. C.; Turner, G.

1995-07-01

Iodine-xenon analyses of chondrules from the Bjurböle L4 and Parnallee LL3.6 meteorites have been made using a continuous wave laser microprobe and the resonance ionisation mass spectrometer RELAX. The excess 129Xe content released from the Bjurböle chondrule is lower than previous stepped-heating studies have found, suggesting that the technique does not completely degas the samples. Nonetheless, clear isochrons were produced, and data for initial 129Xe/130Xe are consistent with earlier work. A correlation is evident in each chondrule between 131Xe* and 128Xe*, perhaps indicating a common host-phase for their parent nuclides, a condition possibly fulfilled by a Te- and I-bearing sulfide. The I-Xe system of a Parnallee macrochondrule exhibits no excess 129Xe, possibly as a result of thermal alteration or deformation before accumulation of the meteorite. A cristobalite-bearing chondrule depleted in 16O yields an I-Xe age of 4.5±.5 Ma after the mean Bjurböle age.

A search for parenting style: a cross-situational analysis of parental behavior.

PubMed

Metsäpelto, R L; Pulkkinen, L; Poikkeus, A M

2001-05-01

Cross-situational stability in parents' emotional warmth and guidance was studied by observing parents (N = 77, M age = 38 years) with their school-aged child in 2 dyadic problem-solving situations and in a family discussion concerning a moral dilemma. The observational data were coded by independent observers using dimensional ratings and dichotomous frequency counts as the 2 coding procedures. These procedures yielded a similar pattern of findings. Parents tended to behave consistently across situations, although the type of situation did affect the amount of emotional warmth and guidance manifested by the parent. Stability was further analyzed by means of structural equation modeling to test whether variance in parents' emotional warmth and guidance across situations was attributable to a generalized parenting style factor. A Parenting Style factor was identified that reflected the parents' child-centeredness; this factor explained, in part, parental behavior within each situation, although contextual factors also contributed to situation-specific variations from task to task.

Public health impact of accelerated immunization against rotavirus infection among children aged less than 6 months in the United States

PubMed Central

Weycker, Derek; Atwood, Mark Andrew; Standaert, Baudouin; Krishnarajah, Girishanthy

2014-01-01

We developed a cohort model to evaluate the expected public health impact of accelerated regimens for immunization against rotavirus gastroenteritis (RVGE). Alternative strategies for vaccination with the pentavalent human-bovine reassortant vaccine, Rotateq® (RV5, Merck) and the oral live attenuated human rotavirus vaccine, Rotarix® (RV1, GlaxoSmithKline Vaccines) were considered, including acceleration of the 1st dose only (by 2 weeks) as well as acceleration of the 1st (by 2 weeks) and subsequent doses (by up to 10 weeks). Assuming vaccine coverage levels consistent with current US clinical practice, accelerated regimens would be expected to reduce annual numbers of RVGE-related hospitalizations by 300–400, emergency department visits by 3000–4000, and outpatient visits by 3000–4000 (i.e., by 9–14%) among US children aged <6 months. Accordingly, accelerating the immunization of children against RVGE may yield substantive reductions in the number of RV-related encounters in US clinical practice. PMID:25424813

Coordinated U–Pb geochronology, trace element, Ti-in-zircon thermometry and microstructural analysis of Apollo zircons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crow, Carolyn A.; McKeegan, Kevin D.; Moser, Desmond E.

Here, we present the results of a coordinated SIMS U–Pb, trace element, Ti-in-zircon thermometry, and microstructural study of 155 lunar zircons separated from Apollo 14, 15, and 17 breccia and soil samples that help resolve discrepancies between the zircon data, the lunar whole rock history and lunar magma ocean crystallization models. The majority of lunar grains are detrital fragments, some nearly 1 mm in length, of large parent crystals suggesting that they crystallized in highly enriched KREEP magmas. The zircon age distributions for all three landing sites exhibit an abundance of ages at ~4.33 Ga, however they differ in thatmore » only Apollo 14 samples have a population of zircons with ages between 4.1 and 3.9 Ga. These younger grains comprise only 10% of all dated lunar zircons and are usually small and highly shocked making them more susceptible to Pb-loss. These observations suggest that the majority of zircons crystallized before 4.1 Ga and that KREEP magmatism had predominantly ceased by this time. We also observed that trace element analyses are easily affected by contributions from inclusions (typically injected impact melt) within SIMS analyses spots. After filtering for these effects, rare-earth element (REE) abundances of pristine zircon are consistent with one pattern characterized by a negative Eu anomaly and no positive Ce anomaly, implying that the zircons formed in a reducing environment. This inference is consistent with crystallization temperatures based on measured Ti concentrations and new estimates of oxide activities which imply temperatures ranging between 958 ± 57 and 1321 ± 100 °C, suggesting that zircon parent magmas were anhydrous. Together, the lunar zircon ages and trace elements are consistent with a ≤300 My duration of KREEP magmatism under anhydrous, reducing conditions. We also report two granular texture zircons that contain baddeleyite cores, which both yield 207Pb– 206Pb ages of 4.33 Ga. These grains are our best constraints on impact ages within our sample population, and suggest at least one large impact is contemporaneous with the most common time of magmatic zircon formation on the Moon’s crust visited by the Apollo missions.« less

Coordinated U–Pb geochronology, trace element, Ti-in-zircon thermometry and microstructural analysis of Apollo zircons

DOE PAGES

Crow, Carolyn A.; McKeegan, Kevin D.; Moser, Desmond E.

2016-12-28

Here, we present the results of a coordinated SIMS U–Pb, trace element, Ti-in-zircon thermometry, and microstructural study of 155 lunar zircons separated from Apollo 14, 15, and 17 breccia and soil samples that help resolve discrepancies between the zircon data, the lunar whole rock history and lunar magma ocean crystallization models. The majority of lunar grains are detrital fragments, some nearly 1 mm in length, of large parent crystals suggesting that they crystallized in highly enriched KREEP magmas. The zircon age distributions for all three landing sites exhibit an abundance of ages at ~4.33 Ga, however they differ in thatmore » only Apollo 14 samples have a population of zircons with ages between 4.1 and 3.9 Ga. These younger grains comprise only 10% of all dated lunar zircons and are usually small and highly shocked making them more susceptible to Pb-loss. These observations suggest that the majority of zircons crystallized before 4.1 Ga and that KREEP magmatism had predominantly ceased by this time. We also observed that trace element analyses are easily affected by contributions from inclusions (typically injected impact melt) within SIMS analyses spots. After filtering for these effects, rare-earth element (REE) abundances of pristine zircon are consistent with one pattern characterized by a negative Eu anomaly and no positive Ce anomaly, implying that the zircons formed in a reducing environment. This inference is consistent with crystallization temperatures based on measured Ti concentrations and new estimates of oxide activities which imply temperatures ranging between 958 ± 57 and 1321 ± 100 °C, suggesting that zircon parent magmas were anhydrous. Together, the lunar zircon ages and trace elements are consistent with a ≤300 My duration of KREEP magmatism under anhydrous, reducing conditions. We also report two granular texture zircons that contain baddeleyite cores, which both yield 207Pb– 206Pb ages of 4.33 Ga. These grains are our best constraints on impact ages within our sample population, and suggest at least one large impact is contemporaneous with the most common time of magmatic zircon formation on the Moon’s crust visited by the Apollo missions.« less

Large Area Crop Inventory Experiment (LACIE). Feasibility of assessing crop condition and yield from LANDSAT data

NASA Technical Reports Server (NTRS)

1978-01-01

The author has identified the following significant results. Yield modelling for crop production estimation derived a means of predicting the within-a-year yield and the year-to-year variability of yield over some fixed or randomly located unit of area. Preliminary studies indicated that the requirements for interpreting LANDSAT data for yield may be sufficiently similar to those of signature extension that it is feasible to investigate the automated estimation of production. The concept of an advanced yield model consisting of both spectral and meteorological components was endorsed. Rationale for using meteorological parameters originated from known between season and near harvest dynamics in crop environmental-condition-yield relationships.

Development of growth and yield models for southern hardwoods: site index determinations

Treesearch

John Paul McTague; Daniel J. Robison; David O' Loughlin; Joseph Roise; Robert Kellison

2006-01-01

Growth and yield data from across 13 southern States, collected from 1967 to 2004 from fully-stocked even-aged southern hardwood forests on a variety of site types, was used to calculate site index curves. These derived curves provide an efficient means to evaluate the productivity-age relation which varies across many sites. These curves were derived for mixed-species...

Deer forage in a loblolly pine plantation

Treesearch

Robert M. Blair

1967-01-01

Browse yields in a 30-year-old plantation thinned at ages 20 and 25 years were directly related to the amount of pine removed and varied from 154 lb (oven-dry) per acre under light thinning to 199 lb/acre under heavy thinning. At plantation age 35, five growing seasons after a third thinning, browse yields were inversely related to pine-thinning intensity, ranging from...

Geomagnetic Investigation of Sandstone Dikes of the Colorado Front Range, for Determination of Age and Mode of Emplacement

NASA Astrophysics Data System (ADS)

Freedman, D.; Petronis, M. S.; Siddoway, C. S.

2012-12-01

In the Colorado Front Range, an array of sandstone dikes has intrigued geologists for over a century (Cross 1894,GSAB, 5, 525). Within their crystalline host, the dikes reach widths >7m and have a lateral extent of 70km along the Ute Pass Fault (UPF). The essential questions of sediment source, emplacement mode, and age of the dikes are unanswered. We present new paleomagnetic, rock magnetic, and anisotropy of magnetic susceptibility (AMS) results used to determine the age and emplacement behavior of the dikes. The eleven dikes selected for magnetic studies have sharp, planar margins, and share the systematic geometry of the NW striking subvertical dike array. They exhibit little or no overprint by brittle fracturing/shear associated with the UPF. Our approach involved the use of paleomagnetic techniques to isolate the characteristic remanent magnetization (ChRM), which we used to limit the age of the dikes' magnetization. Anisotropy of magnetic susceptibility (AMS),arising from alignment of detrital magnetite, serves as a proxy for the orientation of flow during dike emplacement. U-Pb detrital zircon ages, obtained previously, did not provide a useful constraint on emplacement age because the dominant age matches that of the prevalent host,1.03Ga Pikes Peak Granite. IRM acquisition experiments were performed to identify the principal magnetic phases as a mixture of Fe-Ti oxide phases, likely to be low-Ti magnetite and hematite. The sandstone consists of sub-rounded to rounded sand-sized quartz, angular feldspar (<5%), and detrital magnetite; selected samples have uniform grain size and uniform color arising from hematite cement. Although direct cover relationships are not preserved, a portion of the study sites are proximal to in situ near-horizontal sedimentary cover rocks that offer evidence against large tectonic rotation. Cores were collected using a gas-powered drill with a diamond bit and oriented using a sun compass. Where possible, cores were obtained on paired margins to test for directionality of flow using AMS. Paleomagnetic results reveal a magnetization carried by both magnetite and hematite. Laboratory unblocking temperatures for most samples are >600°C. Some samples carry a characteristic remanent magnetization (ChRM) of NW declination with shallow positive inclination, while others yield a characteristic remanent magnetization of SE declination with shallow inclination. By correlation with paleomagnetic results from the region, our findings indicate an age Permian or older. The NW directed ChRM may signify a magnetization of Neoproterozoic age, while the SE directed ChRM is more consistent with a Permo-Carboniferous magnetization. Our investigation of these possibilities is ongoing. Analysis of AMS for nine dike sites yielded subhorizontal strongly prolate magnetic ellipsoids. The magnetic lineation (K1) has moderate plunge and trends NW, parallel to the dike margins. Average bulk susceptibilities (Km) are low (6.39E-5 SI). The AMS characteristics, together with primary sedimentary structures point to instantaneous lateral injection due to elevated pore fluid pressures arising from high lithostatic or tectonic loads. We hypothesize that sediment production and fluid overpressure led to emplacement in a glacial or seismically active setting.

Groundwater Age in Multi-Level Water Quality Monitor Wells on California Central Valley Dairies

NASA Astrophysics Data System (ADS)

Esser, B. K.; Visser, A.; Hillegonds, D. J.; Singleton, M. J.; Moran, J. E.; Harter, T.

2011-12-01

Dairy farming in California's Central Valley is a significant source of nitrate to underlying aquifers. One approach to mitigation is to implement farm-scale management plans that reduce nutrient loading to groundwater while sustaining crop yield. While the effect of different management practices on crop yield is easily measured, their effect on groundwater quality has only infrequently been evaluated. Documenting and predicting the impact of management on water quality requires a quantitative assessment of transport (including timescale and mixing) through the vadose and saturated zones. In this study, we measured tritium, helium isotopic composition, and noble gas concentrations in groundwater drawn from monitor wells on several dairies in the Lower San Joaquin Valley and Tulare Lake Basin of California's Central Valley in order to predict the timescales on which changes in management may produce observable changes in groundwater quality. These dairies differ in age (from <10 to >100 years old), thickness of the vadose zone (from <10 to 60 m), hydrogeologic setting, and primary source of irrigation water (surface or groundwater). All of the dairies use manure wastewater for irrigation and fertilization. Three of the dairies have implemented management changes designed to reduce nutrient loading and/or water usage. Monitor wells in the southern Tulare Lake Basin dairies were installed by UC-Davis as multi-level nested wells allowing depth profiling of tritium and noble gases at these sites. Tritium/helium-3 groundwater ages, calculated using a simple piston-flow model, range from <2 to >50 years. Initial tritium (the sum of measured tritium and tritiogenic helium-3) is close to or slightly above precipitation in the calculated recharge year for young samples; and significantly above the precipitation curve for older samples. This pattern is consistent with the use of 20-30 year old groundwater recharged before 1980 for irrigation, and illustrates how irrigation with groundwater can complicate the use of tritium alone for age dating. The presence of radiogenic helium-4 in several samples with measurable tritium provides evidence of mixing between pre-modern and younger groundwater. Groundwater age-depth relationships are complicated, consistent with transient flow patterns in shallow agricultural groundwaters affected by irrigation pumping and recharge. For the multi-level installations in the southern dairies, both depth profiles and re-sampling after significant changes in groundwater elevation emphasize the need to sample groundwater within 3 meters of the water table to obtain "first-encounter" groundwater with a tritium/helium-3 age of less than 5 years, and to use age tracers to identify wells and groundwater conditions suitable for monitoring and assessment of best management practice impacts on underlying groundwater quality. This work was carried out with funding from Sustainable Conservation and the California State Water Resources Control Board in collaboration with UC-Davis, and was performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344.

Water quality in the St Croix National Scenic Riverway, Wisconsin

USGS Publications Warehouse

Graczyk, D.J.

1986-01-01

Yields for suspended sediment, total phosphorus, total nitrogen, and dissolved solids at the study stations were consistently lower than at other stations in the State. Suspendedsediment yields ranged from 1.9 to 13.3 tons per square mile. The average suspended-sediment yield for Wisconsin is 80 tons per square mile. Total phosphorous and the other constituents exhibited the same trend.

Modeling precipitation-runoff relationships to determine water yield from a ponderosa pine forest watershed

Treesearch

Assefa S. Desta

2006-01-01

A stochastic precipitation-runoff modeling is used to estimate a cold and warm-seasons water yield from a ponderosa pine forested watershed in the north-central Arizona. The model consists of two parts namely, simulation of the temporal and spatial distribution of precipitation using a stochastic, event-based approach and estimation of water yield from the watershed...

Minimization of Residual Stress in an Al-Cu Alloy Forged Plate by Different Heat Treatments

NASA Astrophysics Data System (ADS)

Dong, Ya-Bo; Shao, Wen-Zhu; Jiang, Jian-Tang; Zhang, Bao-You; Zhen, Liang

2015-06-01

In order to improve the balance of mechanical properties and residual stress, various quenching and aging treatments were applied to Al-Cu alloy forged plate. Residual stresses determined by the x-ray diffraction method and slitting method were compared. The surface residual stress measured by x-ray diffraction method was consistent with that measured by slitting method. The residual stress distribution of samples quenched in water with different temperatures (20, 60, 80, and 100 °C) was measured, and the results showed that the boiling water quenching results in a 91.4% reduction in residual stress magnitudes compared with cold water quenching (20 °C), but the tensile properties of samples quenched in boiling water were unacceptably low. Quenching in 80 °C water results in 75% reduction of residual stress, and the reduction of yield strength is 12.7%. The residual stress and yield strength level are considerable for the dimensional stability of aluminum alloy. Quenching samples into 30% polyalkylene glycol quenchants produced 52.2% reduction in the maximum compressive residual stress, and the reduction in yield strength is 19.7%. Moreover, the effects of uphill quenching and thermal-cold cycling on the residual stress were also investigated. Uphill quenching and thermal-cold cycling produced approximately 25-40% reduction in residual stress, while the effect on tensile properties is quite slight.

Evaluation of the CEAS trend and monthly weather data models for soybean yields in Iowa, Illinois, and Indiana

NASA Technical Reports Server (NTRS)

French, V. (Principal Investigator)

1982-01-01

The CEAS models evaluated use historic trend and meteorological and agroclimatic variables to forecast soybean yields in Iowa, Illinois, and Indiana. Indicators of yield reliability and current measures of modeled yield reliability were obtained from bootstrap tests on the end of season models. Indicators of yield reliability show that the state models are consistently better than the crop reporting district (CRD) models. One CRD model is especially poor. At the state level, the bias of each model is less than one half quintal/hectare. The standard deviation is between one and two quintals/hectare. The models are adequate in terms of coverage and are to a certain extent consistent with scientific knowledge. Timely yield estimates can be made during the growing season using truncated models. The models are easy to understand and use and are not costly to operate. Other than the specification of values used to determine evapotranspiration, the models are objective. Because the method of variable selection used in the model development is adequately documented, no evaluation can be made of the objectivity and cost of redevelopment of the model.

Evaluating the utility of detrital thermochronometric studies: detrital laser ablation (U-Th)/He dating and conventional bedrock zircon (U-Th)/He analyses from the eastern Sierra Nevada, California

NASA Astrophysics Data System (ADS)

Horne, A.; Hodges, K. V.; Van Soest, M. C.

2016-12-01

Recent applications of the newly developed `laser ablation double dating' (LADD) technique, an integrated laser microprobe U/Pb and (U-Th)/He dating method, have showcased the potential utility of LADD for detrital thermochronologic studies. However, detrital thermochronologic techniques rely on confidence that detrital data adequately represent the full range of bedrock cooling ages within a catchment. To test this primary assumption, we compare (U-Th)/He zircon ages from age-elevation transects to LADD (U-Th)/He zircon ages from modern fluvial detritus collected at the range front in the eastern Sierra Nevada, California. Terminated by a normal fault escarpment, the small, steep catchments along the eastern side of the Sierra Nevada batholith are apropos locations for comparing the ability of detrital data to deduce the exhumation history of a source terrain with standard age-elevation transects. Additionally, the exhumation of the Sierra Nevada batholith is also intriguing, as past evaluations of the post-emplacement exhumation history of the range have yielded discrepant results. Thus far, analyses from the southern extent of the eastern Sierra Nevada show narrow ranges of cooling ages consistent with simple, relatively rapid exhumation. Ongoing analyses will expand the dataset such that we can fully compare bedrock and detrital age ranges as well as characterize the exhumation history of the range with a thermochronometer that has not been used to date the batholith.

Antioxidants can extend lifespan of Brachionus manjavacas (Rotifera), but only in a few combinations

PubMed Central

Fields, Allison M.; Johnston, Rachel K.

2013-01-01

Animal cells are protected from oxidative damage by an antioxidant network operating as a coordinated system, with strong synergistic interactions. Lifespan studies with whole animals are expensive and laborious, so there has been little investigation of which antioxidant interactions might be useful for life extension. Animals in the phylum Rotifera are particularly promising models for aging studies because they are small (0.1–1 mm), have short, two-week lifespan, display typical patterns of animal aging, and have well characterized, easy to measure phenotypes of aging and senescence. One class of interventions that has consistently produced significant rotifer life extension is antioxidants. Although the mechanism of antioxidant effects on animal aging remains controversial, the ability of some antioxidant supplements to extend rotifer lifespan was unequivocal. We found that exposing rotifers to certain combinations of antioxidant supplements can produce up to about 20% longer lifespan, but that most antioxidants have no effect. We performed life table tests with 20 single antioxidants and none yielded significant rotifer life extension. We tested 60 two-way combinations of selected antioxidants and only seven (12%) produced significant rotifer life extension. None of the 20 three- and four-way antioxidant combinations tested yielded significant rotifer life extension. These observations suggest that dietary exposure of antioxidants can extend rotifer lifespan, but most antioxidants do not. We observed significant rotifer life extension only when antioxidants were paired with trolox, N-acetyl cysteine, l-carnosine, or EUK-8. This illustrates that antioxidant treatments capable of rotifer life extension are patchily distributed in the parameter space, so large regions must be searched to find them. It furthermore underscores the value of the rotifer model to conduct rapid, facile life table experiments with many treatments, which makes such a search feasible. Although some antioxidants extended rotifer lifespan, they likely did so by another mechanism than direct antioxidation. PMID:22270335

Antioxidants can extend lifespan of Brachionus manjavacas (Rotifera), but only in a few combinations.

PubMed

Snell, Terry W; Fields, Allison M; Johnston, Rachel K

2012-06-01

Animal cells are protected from oxidative damage by an antioxidant network operating as a coordinated system, with strong synergistic interactions. Lifespan studies with whole animals are expensive and laborious, so there has been little investigation of which antioxidant interactions might be useful for life extension. Animals in the phylum Rotifera are particularly promising models for aging studies because they are small (0.1-1 mm), have short, two-week lifespan, display typical patterns of animal aging, and have well characterized, easy to measure phenotypes of aging and senescence. One class of interventions that has consistently produced significant rotifer life extension is antioxidants. Although the mechanism of antioxidant effects on animal aging remains controversial, the ability of some antioxidant supplements to extend rotifer lifespan was unequivocal. We found that exposing rotifers to certain combinations of antioxidant supplements can produce up to about 20% longer lifespan, but that most antioxidants have no effect. We performed life table tests with 20 single antioxidants and none yielded significant rotifer life extension. We tested 60 two-way combinations of selected antioxidants and only seven (12%) produced significant rotifer life extension. None of the 20 three- and four-way antioxidant combinations tested yielded significant rotifer life extension. These observations suggest that dietary exposure of antioxidants can extend rotifer lifespan, but most antioxidants do not. We observed significant rotifer life extension only when antioxidants were paired with trolox, N-acetyl cysteine, L: -carnosine, or EUK-8. This illustrates that antioxidant treatments capable of rotifer life extension are patchily distributed in the parameter space, so large regions must be searched to find them. It furthermore underscores the value of the rotifer model to conduct rapid, facile life table experiments with many treatments, which makes such a search feasible. Although some antioxidants extended rotifer lifespan, they likely did so by another mechanism than direct antioxidation.

Lithospheric bending at subduction zones based on depth soundings and satellite gravity

NASA Technical Reports Server (NTRS)

Levitt, Daniel A.; Sandwell, David T.

1995-01-01

A global study of trench flexure was performed by simultaneously modeling 117 bathymetric profiles (original depth soundings) and satellite-derived gravity profiles. A thin, elastic plate flexure model was fit to each bathymetry/gravity profile by minimization of the L(sub 1) norm. The six model parameters were regional depth, regional gravity, trench axis location, flexural wavelength, flexural amplitude, and lithospheric density. A regional tilt parameter was not required after correcting for age-related trend using a new high-resolution age map. Estimates of the density parameter confirm that most outer rises are uncompensated. We find that flexural wavelength is not an accurate estimate of plate thickness because of the high curvatures observed at a majority of trenches. As in previous studies, we find that the gravity data favor a longer-wavelength flexure than the bathymetry data. A joint topography-gravity modeling scheme and fit criteria are used to limit acceptable parameter values to models for which topography and gravity yield consistent results. Even after the elastic thicknesses are converted to mechanical thicknesses using the yield strength envelope model, residual scatter obscures the systematic increase of mechanical thickness with age; perhaps this reflects the combination of uncertainties inherent in estimating flexural wavelength, such as extreme inelastic bending and accumulated thermoelastic stress. The bending moment needed to support the trench and outer rise topography increases by a factor of 10 as lithospheric age increases from 20 to 150 Ma; this reflects the increase in saturation bending moment that the lithosphere can maintain. Using a stiff, dry-olivine rheology, we find that the lithosphere of the GDH1 thermal model (Stein and Stein, 1992) is too hot and thin to maintain the observed bending moments. Moreover, the regional depth seaward of the oldest trenches (approximately 150 Ma) exceeds the GDH1 model depths by about 400 m.

Syn-convergence extension in the southern Lhasa terrane: Evidence from late Cretaceous adakitic granodiorite and coeval gabbroic-dioritic dykes

NASA Astrophysics Data System (ADS)

Ma, Xuxuan; Xu, Zhiqin; Meert, Joseph G.

2017-10-01

Late Cretaceous (∼100-80 Ma) magmatism in the Gangdese magmatic belt plays a pivotal role in understanding the evolutionary history and tectonic regime of the southern Lhasa terrane. The geodynamic process for the formation of the early Late Cretaceous magmatism has long been an issue of hot debates. Here, petrology, geochronology and geochemistry of early Late Cretaceous granodiorite and coeval gabbroic-dioritic dykes in the Caina region, southern Lhasa, were investigated in an effort to ascertain their petrogenesis, age of intrusion, magma mixing and tectonic setting. Zircon U-Pb dating of granodiorite yields 206Pb/238U ages of 85.8 ± 1.7 and 86.4 ± 1.1 Ma, whilst that of the E-W trending dykes yields ages of 82.7 ± 2.6 and 83.5 ± 3.5 Ma. Within error, the crystallization ages of the dykes and the granodiorite are indistinguishable. Field observations and mineralogical microstructures are suggestive of a magma mixing process during the formation of the dykes and the granodiorite. The granodiorite exhibits geochemical features that are in agreement with those of subduction-related high-SiO2 adakites. The granodiorite and dykes have relatively constant εNd(t) values of +2.2 to +4.9 and initial 87Sr/86Sr ratios (0.7045-0.7047). These similar characteristics are herein interpreted as an evolutionary series from the dykes to granodiorite, consistent with magma mixing process. Ti-in-zircon thermometer and Al-in-hornblende barometer indicate that the granodiorite and the dioritic dyke crystallized at temperatures of ca. 750 and 800 °C, depths of ca. 6-10 and 5-9 km, respectively. Taking into account the synchronous magmatic rocks in the Gangdese Belt and the coeval rifted basin within the Lhasa terrane, the granodiorite and dykes reveal an early Late Cretaceous syn-convergence extensional regime in the southern Lhasa terrane, triggered by slab rollback of the Neotethyan oceanic lithosphere.

Connecting to Young Adults: An Online Social Network Survey of Beliefs and Attitudes Associated With Prescription Opioid Misuse Among College Students

PubMed Central

Lord, Sarah; Brevard, Julie; Budman, Simon

2011-01-01

A survey of motives and attitudes associated with patterns of nonmedical prescription opioid medication use among college students was conducted on Facebook, a popular online social networking Web site. Response metrics for a 2-week random advertisement post, targeting students who had misused prescription medications, surpassed typical benchmarks for online marketing campaigns and yielded 527 valid surveys. Respondent characteristics, substance use patterns, and use motives were consistent with other surveys of prescription opioid use among college populations. Results support the potential of online social networks to serve as powerful vehicles to connect with college-aged populations about their drug use. Limitations of the study are noted. PMID:21190407

A Diversified Recruitment Approach Incorporating Social Media Leads to Research Participation Among Young Adult-Aged Female Cancer Survivors.

PubMed

Gorman, Jessica R; Roberts, Samantha C; Dominick, Sally A; Malcarne, Vanessa L; Dietz, Andrew C; Su, H Irene

2014-06-01

Purpose: Cancer survivors in their adolescent and young adult (AYA) years are an understudied population, possibly in part because of the high effort required to recruit them into research studies. The aim of this paper is to describe the specific recruitment strategies used in four studies recruiting AYA-aged female cancer survivors and to identify the highest yielding approaches. We also discuss challenges and recommendations. Methods: We recruited AYA-aged female cancer survivors for two studies conducted locally and two conducted nationally. Recruitment strategies included outreach and referral via: healthcare providers and clinics; social media and the internet; community and word of mouth; and a national fertility information hotline. We calculated the yield of each recruitment approach for the local and national studies by comparing the number that participated to the number of potential participants. Results: We recruited a total of 534 participants into four research studies. Seventy-one percent were diagnosed as young adults and 61% were within 3 years of their cancer diagnosis. The highest-yielding local recruitment strategy was healthcare provider and clinic referral. Nationally, social media and internet outreach yielded the highest rate of participation. Overall, internet-based recruitment resulted in the highest number and yield of participants. Conclusion: Our results suggest that outreach through social media and the internet are effective approaches to recruiting AYA-aged female cancer survivors. Forging collaborative relationships with survivor advocacy groups' members and healthcare providers also proved beneficial.

A Diversified Recruitment Approach Incorporating Social Media Leads to Research Participation Among Young Adult-Aged Female Cancer Survivors

PubMed Central

Gorman, Jessica R.; Roberts, Samantha C.; Dominick, Sally A.; Malcarne, Vanessa L.; Dietz, Andrew C.

2014-01-01

Purpose: Cancer survivors in their adolescent and young adult (AYA) years are an understudied population, possibly in part because of the high effort required to recruit them into research studies. The aim of this paper is to describe the specific recruitment strategies used in four studies recruiting AYA-aged female cancer survivors and to identify the highest yielding approaches. We also discuss challenges and recommendations. Methods: We recruited AYA-aged female cancer survivors for two studies conducted locally and two conducted nationally. Recruitment strategies included outreach and referral via: healthcare providers and clinics; social media and the internet; community and word of mouth; and a national fertility information hotline. We calculated the yield of each recruitment approach for the local and national studies by comparing the number that participated to the number of potential participants. Results: We recruited a total of 534 participants into four research studies. Seventy-one percent were diagnosed as young adults and 61% were within 3 years of their cancer diagnosis. The highest-yielding local recruitment strategy was healthcare provider and clinic referral. Nationally, social media and internet outreach yielded the highest rate of participation. Overall, internet-based recruitment resulted in the highest number and yield of participants. Conclusion: Our results suggest that outreach through social media and the internet are effective approaches to recruiting AYA-aged female cancer survivors. Forging collaborative relationships with survivor advocacy groups' members and healthcare providers also proved beneficial. PMID:24940529

In Situ UV-Laser Ablation 40Ar/39Ar Muscovite Thermochronology Reveals Excess Argon and 405-399 Ma Age for the Nordfjord-Sogn Detachment Zone, Hornelen region, Norway

NASA Astrophysics Data System (ADS)

Johnston, S. M.; Hacker, B. R.; Eide, E. A.; Hendriks, B.

2006-12-01

The Nordfjord-Sogn Detachment Zone (NSDZ) is a 2-6 km thick, normal-sense shear zone that juxtaposes the eclogite-bearing Western Gneiss Complex in its footwall with Devonian sediments in its hangingwall, and is widely cited as the primary structure responsible for the exhumation of the Norwegian ultrahigh-pressure (UHP) rocks. Critical to our understanding of this crustal-scale detachment, detailed thermochronology places essential constraints on the rates of exhumation and documents spatial variability in the timing of exhumation- related cooling. Regional thermochronology has shown that 40Ar/39Ar muscovite ages increase gradually from 405-390 Ma across the Western Gneiss Complex and into the lower part of the NSDZ, but at higher structural levels within the NSDZ, these ~400 Ma ages are mixed with an older population at 420-418 Ma. Although neither excess argon nor incomplete resetting of argon in these older samples has been ruled out, these results have been interpreted to suggest that extension and exhumation within the NSDZ may have initiated as early as 420 Ma. Here, we investigate these older 40Ar/39Ar muscovite ages by comparing resistance furnace (RF) ages from bulk muscovite separates with in situ UV-laser ablation ages from a suite of 6 samples that transect the NSDZ. RF spectra from 5 of the 6 analyzed samples yield plateau ages that range from 405-399 Ma; in situ ages of these same 5 samples reveal no age zonation within large grains and no differences in ages among texturally different grains. In contrast, the structurally highest sample yields a RF plateau age of 425±6 Ma, and in situ ages of 474-417 Ma in grain cores and c. 400 Ma in grain rims and small grains. On an inverse isochron diagram, these in situ ages define two distinct populations, with grain cores distributed along a line between an excess argon component of 40Ar/36Ar = 660±60 and an age of 404±7 Ma. Analyses from rims and small grains plot in triangle defined by these two apices and an atmospheric 40Ar/36Ar ratio. These results are consistent with the interpretation that the older 40Ar/39Ar muscovite ages from the NSDZ are the result of excess argon. These findings refute the possibility of extension and exhumation as early as 420 Ma along the NSDZ, and suggest that the entire package of NSDZ mylonites was cooled through muscovite closure to argon between 405-399 Ma immediately following UHP metamorphism.

Associations between age at first calving and subsequent lactation performance in UK Holstein and Holstein-Friesian dairy cows

PubMed Central

Eastham, Neil T.; Coates, Amy; Cripps, Peter; Richardson, Henry; Smith, Robert

2018-01-01

Lactation records from 396,534 pedigree Holstein and Holstein-Friesian primiparous cows from 6,985 UK milk recorded herds, calving for the first time during the period between the 1st of January 2006 and the 31st of December 2008, were examined in order to determine the associations between age at first calving (AFC) and subsequent production, udder health, fertility and survivability parameters. Heifers were grouped by AFC into single month classes ranging from 21 to 42 months. Mixed effects multivariable regression modelling was used for data analysis. Mean and median AFC were 29.1 and 28 months respectively. Within the study, only 48,567 heifers (12.3% of the studied population) calved for the first time at 24 months of age or younger. 162,157 heifers (40.9%) were 30 months or older at their first calving. An increased AFC was associated with increased first lactation milk, fat and protein yields. The lowest predicted mean 305-day yield (6,617kgs; 95% confidence interval (CI): 6,546–6,687 kgs) was recorded for the 21 month AFC class, significantly lower than any other class. The 36 month AFC class had the highest predicted mean (7,774 kgs; 95% CI: 7,737–7,811 kgs). However, an increased AFC was also associated with increased calving interval and increased first lactation somatic cell count (SCC). Animals calving at 21 months had a predicted mean lactation SCC of 72,765 (95% CI: 68427–77378). Animals calving at 36 months of age had a predicted mean lactation SCC of 86,648 (95% CI: 84,499–88,853). Importantly, an increased AFC was also associated with decreased lifetime daily milk yield and decreased likelihood of calving for a second successive time. Animals calving at 22 months of age had a predicted mean daily lifetime milk yield of 15.24 kgs (95% CI: 15.06–15.35); animals calving at 36 months of age had a predicted mean daily lifetime milk yield of 12.83 kgs (95% CI: 12.76–12.91). Our results highlight the importance of achieving a lower age at first calving which was here associated with improved udder health, increased lifetime daily milk yield, improved reproductive performance and increased likelihood of calving for a second time. PMID:29897929

Associations between age at first calving and subsequent lactation performance in UK Holstein and Holstein-Friesian dairy cows.

PubMed

Eastham, Neil T; Coates, Amy; Cripps, Peter; Richardson, Henry; Smith, Robert; Oikonomou, Georgios

2018-01-01

Lactation records from 396,534 pedigree Holstein and Holstein-Friesian primiparous cows from 6,985 UK milk recorded herds, calving for the first time during the period between the 1st of January 2006 and the 31st of December 2008, were examined in order to determine the associations between age at first calving (AFC) and subsequent production, udder health, fertility and survivability parameters. Heifers were grouped by AFC into single month classes ranging from 21 to 42 months. Mixed effects multivariable regression modelling was used for data analysis. Mean and median AFC were 29.1 and 28 months respectively. Within the study, only 48,567 heifers (12.3% of the studied population) calved for the first time at 24 months of age or younger. 162,157 heifers (40.9%) were 30 months or older at their first calving. An increased AFC was associated with increased first lactation milk, fat and protein yields. The lowest predicted mean 305-day yield (6,617kgs; 95% confidence interval (CI): 6,546-6,687 kgs) was recorded for the 21 month AFC class, significantly lower than any other class. The 36 month AFC class had the highest predicted mean (7,774 kgs; 95% CI: 7,737-7,811 kgs). However, an increased AFC was also associated with increased calving interval and increased first lactation somatic cell count (SCC). Animals calving at 21 months had a predicted mean lactation SCC of 72,765 (95% CI: 68427-77378). Animals calving at 36 months of age had a predicted mean lactation SCC of 86,648 (95% CI: 84,499-88,853). Importantly, an increased AFC was also associated with decreased lifetime daily milk yield and decreased likelihood of calving for a second successive time. Animals calving at 22 months of age had a predicted mean daily lifetime milk yield of 15.24 kgs (95% CI: 15.06-15.35); animals calving at 36 months of age had a predicted mean daily lifetime milk yield of 12.83 kgs (95% CI: 12.76-12.91). Our results highlight the importance of achieving a lower age at first calving which was here associated with improved udder health, increased lifetime daily milk yield, improved reproductive performance and increased likelihood of calving for a second time.

Comparison of Online Survey Recruitment Platforms for Hard-to-Reach Pregnant Smoking Populations: Feasibility Study.

PubMed

Ibarra, Jose Luis; Agas, Jessica Marie; Lee, Melissa; Pan, Julia Lily; Buttenheim, Alison Meredith

2018-04-16

Recruiting hard-to-reach populations for health research is challenging. Web-based platforms offer one way to recruit specific samples for research purposes, but little is known about the feasibility of online recruitment and the representativeness and comparability of samples recruited through different Web-based platforms. The objectives of this study were to determine the feasibility of recruiting a hard-to-reach population (pregnant smokers) using 4 different Web-based platforms and to compare participants recruited through each platform. A screener and survey were distributed online through Qualtrics Panel, Soapbox Sample, Reddit, and Amazon Mechanical Turk (mTurk). Descriptive statistics were used to summarize results of each recruitment platform, including eligibility yield, quality yield, income, race, age, and gestational age. Of the 3847 participants screened for eligibility across all 4 Web-based platforms, 535 were eligible and 308 completed the survey. Amazon mTurk yielded the fewest completed responses (n=9), 100% (9/9) of which passed several quality metrics verifying pregnancy and smoking status. Qualtrics Panel yielded 14 completed responses, 86% (12/14) of which passed the quality screening. Soapbox Sample produced 107 completed surveys, 67% (72/107) of which were found to be quality responses. Advertising through Reddit produced the highest completion rate (n=178), but only 29.2% (52/178) of those surveys passed the quality metrics. We found significant differences in eligibility yield, quality yield, age, number of previous pregnancies, age of smoking initiation, current smokers, race, education, and income (P<.001). Although each platform successfully recruited pregnant smokers, results varied in quality, cost, and percentage of complete responses. Moving forward, investigators should pay careful attention to the percentage yield and cost of online recruitment platforms to maximize internal and external validity. ©Jose Luis Ibarra, Jessica Marie Agas, Melissa Lee, Julia Lily Pan, Alison Meredith Buttenheim. Originally published in JMIR Research Protocols (http://www.researchprotocols.org), 16.04.2018.

Evidence of Middle Jurassic magmatism within the Seychelles microcontinent: Implications for the breakup of Gondwana

NASA Astrophysics Data System (ADS)

Shellnutt, J. G.; Lee, T.-Y.; Chiu, H.-Y.; Lee, Y.-H.; Wong, J.

2015-12-01

The breakup of East and West Gondwana occurred during the Jurassic, but the exact timing is uncertain due to the limited exposure of rocks suitable for radioisotopic dating. Trachytic rocks from Silhouette Island, Seychelles, yielded a range of zircon ages from Paleoproterozoic to Cenozoic. The 206Pb/238U age of the trachyte is 64.9 ± 1.6 Ma (Danian) but the majority of zircons yielded an age of 163.8 ± 1.8 Ma (Callovian) with a small subset yielding an age of 147.7 ± 4.5 Ma (Tithonian). The Hf isotopes of the Callovian (ɛHf(t) = +4.1 to +13.4) and Danian (ɛHf(t) = +1.9 to +7.1) zircons indicate that they were derived from moderately depleted mantle sources whereas the Tithonian zircons (ɛHf(t) = -7.0 to -7.3) were derived from an enriched source. The identification of middle Jurassic zircons indicates that rifting and magmatism were likely contemporaneous during the initial separation of East and West Gondwana.

Senescence marker protein 30 (SMP30)/regucalcin (RGN) expression decreases with aging, acute liver injuries and tumors in zebrafish

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fujisawa, Koichi; Terai, Shuji, E-mail: terais@yamaguchi-u.ac.jp; Hirose, Yoshikazu

2011-10-22

Highlights: {yields} Zebrafish SMP30/RGN mRNA expression decreases with aging. {yields} Decreased expression was observed in liver tumors as compared to the surrounding area. {yields} SMP30/RGN is important for liver proliferation and tumorigenesis. -- Abstract: Senescence marker protein 30 (SMP30)/regucalcin (RGN) is known to be related to aging, hepatocyte proliferation and tumorigenesis. However, expression and function of non-mammalian SMP30/RGN is poorly understood. We found that zebrafish SMP30/RGN mRNA expression decreases with aging, partial hepatectomy and thioacetamide-induced acute liver injury. SMP30/RGN expression was also greatly decreased in a zebrafish liver cell line. In addition, we induced liver tumors in adult zebrafish bymore » administering diethylnitrosamine. Decreased expression was observed in foci, hepatocellular carcinomas, cholangiocellular carcinomas and mixed tumors as compared to the surrounding area. We thus showed the importance of SMP30/RGN in liver proliferation and tumorigenesis.« less

Temporal and structural evolution of the Early Palæogene rocks of the Seychelles microcontinent.

PubMed

Shellnutt, J Gregory; Yeh, Meng-Wan; Suga, Kenshi; Lee, Tung-Yi; Lee, Hao-Yang; Lin, Te-Hsien

2017-03-14

The Early Palæogene Silhouette/North Island volcano-plutonic complex was emplaced during the rifting of the Seychelles microcontinent from western India. The complex is thought to have been emplaced during magnetochron C28n. However, the magnetic polarities of the rocks are almost entirely reversed and inconsistent with a normal polarity. In this study we present new in situ zircon U/Pb geochronology of the different intrusive facies of the Silhouette/North Island complex in order to address the timing of emplacement and the apparent magnetic polarity dichotomy. The rocks from Silhouette yielded weighted mean 206 Pb/ 238 U ages from 62.4 ± 0.9 Ma to 63.1 ± 0.9 Ma whereas the rocks from North Island yielded slightly younger mean ages between 60.6 ± 0.7 Ma to 61.0 ± 0.8 Ma. The secular latitudinal variation from Silhouette to North Island is consistent with the anticlockwise rotation of the Seychelles microcontinent and the measured polarities. The rocks from Silhouette were emplaced across a polarity cycle (C26r-C27n-C27r) and the rocks from North Island were emplaced entirely within a magnetic reversal (C26r). Moreover, the rocks from North Island and those from the conjugate margin of India are contemporaneous and together mark the culmination of rift-related magmatism.

Random regression analyses using B-splines to model growth of Australian Angus cattle

PubMed Central

Meyer, Karin

2005-01-01

Regression on the basis function of B-splines has been advocated as an alternative to orthogonal polynomials in random regression analyses. Basic theory of splines in mixed model analyses is reviewed, and estimates from analyses of weights of Australian Angus cattle from birth to 820 days of age are presented. Data comprised 84 533 records on 20 731 animals in 43 herds, with a high proportion of animals with 4 or more weights recorded. Changes in weights with age were modelled through B-splines of age at recording. A total of thirteen analyses, considering different combinations of linear, quadratic and cubic B-splines and up to six knots, were carried out. Results showed good agreement for all ages with many records, but fluctuated where data were sparse. On the whole, analyses using B-splines appeared more robust against "end-of-range" problems and yielded more consistent and accurate estimates of the first eigenfunctions than previous, polynomial analyses. A model fitting quadratic B-splines, with knots at 0, 200, 400, 600 and 821 days and a total of 91 covariance components, appeared to be a good compromise between detailedness of the model, number of parameters to be estimated, plausibility of results, and fit, measured as residual mean square error. PMID:16093011

Determination of Yield in Inconel 718 for Axial-Torsional Loading at Temperatures up to 649 C

NASA Technical Reports Server (NTRS)

Gil, Christopher M.; Lissenden, Cliff J.; Lerch, Bradley A.

1998-01-01

An experimental program has been implemented to determine small offset yield loci under axial-torsional loading at elevated temperatures. The nickel-base superalloy Inconel 718 (IN718) was chosen for study due to its common use in aeropropulsion applications. Initial and subsequent yield loci were determined for solutioned IN718 at 23, 371, and 454 C and for aged (precipitation hardened) IN718 at 23 and 649 C. The shape of the initial yield loci for solutioned and aged IN718 agreed well with the von Mises prediction. However, in general, the centers of initial yield loci were eccentric to the origin due to a strength-differential (S-D) effect that increased with temperature. Subsequent yield loci exhibited anisotropic hardening in the form of translation and distortion of the locus. This work shows that it is possible to determine yield surfaces for metallic materials at temperatures up to at least 649 C using multiple probes of a single specimen. The experimental data is first-of-its-kind for a superalloy at these very high temperatures and will facilitate a better understanding of multiaxial material response, eventually leading to improved design tools for engine designers.

Changing forest water yields in response to climate warming: results from long-term experimental watershed sites across North America

Treesearch

Irena F. Creed; Adam T. Spargo; Julia A. Jones; Jim M. Buttle; Mary B. Adams; Fred D. Beall; Eric G. Booth; John L. Campbell; Dave Clow; Kelly Elder; Mark B. Green; Nancy B. Grimm; Chelcy Miniat; Patricia Ramlal; Amartya Saha; Stephen Sebestyen; Dave Spittlehouse; Shannon Sterling; Mark W. Williams; Rita Winkler; Huaxia Yao

2014-01-01

Climate warming is projected to affect forest water yields but the effects are expected to vary.We investigated how forest type and age affect water yield resilience to climate warming. To answer this question, we examined the variability in historical water yields at long-term experimental catchments across Canada and the United States over 5-year cool and warm...

Illusory Late Heavy Bombardments

NASA Astrophysics Data System (ADS)

Boehnke, Patrick; Harrison, T. Mark

2016-09-01

The Late Heavy Bombardment (LHB), a hypothesized impact spike at ˜3.9 Ga, is one of the major scientific concepts to emerge from Apollo-era lunar exploration. A significant portion of the evidence for the existence of the LHB comes from histograms of 40Ar/39Ar “plateau” ages (i.e., regions selected on the basis of apparent isochroneity). However, due to lunar magmatism and overprinting from subsequent impact events, virtually all Apollo-era samples show evidence for 40Ar/39Ar age spectrum disturbances, leaving open the possibility that partial 40Ar* resetting could bias interpretation of bombardment histories due to plateaus yielding misleadingly young ages. We examine this possibility through a physical model of 40Ar* diffusion in Apollo samples and test the uniqueness of the impact histories obtained by inverting plateau age histograms. Our results show that plateau histograms tend to yield age peaks, even in those cases where the input impact curve did not contain such a spike, in part due to the episodic nature of lunar crust or parent body formation. Restated, monotonically declining impact histories yield apparent age peaks that could be misinterpreted as LHB-type events. We further conclude that the assignment of apparent 40Ar/39Ar plateau ages bears an undesirably high degree of subjectivity. When compounded by inappropriate interpretations of histograms constructed from plateau ages, interpretation of apparent, but illusory, impact spikes is likely.

Illusory Late Heavy Bombardments

PubMed Central

Boehnke, Patrick; Harrison, T. Mark

2016-01-01

The Late Heavy Bombardment (LHB), a hypothesized impact spike at ∼3.9 Ga, is one of the major scientific concepts to emerge from Apollo-era lunar exploration. A significant portion of the evidence for the existence of the LHB comes from histograms of 40Ar/39Ar “plateau” ages (i.e., regions selected on the basis of apparent isochroneity). However, due to lunar magmatism and overprinting from subsequent impact events, virtually all Apollo-era samples show evidence for 40Ar/39Ar age spectrum disturbances, leaving open the possibility that partial 40Ar* resetting could bias interpretation of bombardment histories due to plateaus yielding misleadingly young ages. We examine this possibility through a physical model of 40Ar* diffusion in Apollo samples and test the uniqueness of the impact histories obtained by inverting plateau age histograms. Our results show that plateau histograms tend to yield age peaks, even in those cases where the input impact curve did not contain such a spike, in part due to the episodic nature of lunar crust or parent body formation. Restated, monotonically declining impact histories yield apparent age peaks that could be misinterpreted as LHB-type events. We further conclude that the assignment of apparent 40Ar/39Ar plateau ages bears an undesirably high degree of subjectivity. When compounded by inappropriate interpretations of histograms constructed from plateau ages, interpretation of apparent, but illusory, impact spikes is likely. PMID:27621460

Growth and yield in Eucalyptus globulus

Treesearch

James A. Rinehart; Richard B. Standiford

1983-01-01

A study of the major Eucalyptus globulus stands throughout California conducted by Woodbridge Metcalf in 1924 provides a complete and accurate data set for generating variable site-density yield models. Two models were developed using linear regression techniques. Model I depicts a linear relationship between age and yield best used for stands between five and fifteen...

An evaluation of three growth and yield simulators for even-aged hardwood forests of the mid-Appalachian region

Treesearch

John R. Brooks; Gary W. Miller

2011-01-01

Data from even-aged hardwood stands in four ecoregions across the mid-Appalachian region were used to test projection accuracy for three available growth and yield software systems: SILVAH, the Forest Vegetation Simulator, and the Stand Damage Model. Average root mean squared error (RMSE) ranged from 20 to 140 percent of actual trees per acre while RMSE ranged from 2...

Analysis of low-marbled Hanwoo cow meat aged with different dry-aging methods

PubMed Central

Lee, Hyun Jung; Choe, Juhui; Kim, Kwan Tae; Oh, Jungmin; Lee, Da Gyeom; Kwon, Ki Moon; Choi, Yang Il; Jo, Cheorun

2017-01-01

Objective Different dry-aging methods [traditional dry-aging (TD), simplified dry-aging (SD), and SD in an aging bag (SDB)] were compared to investigate the possible use of SD and/or SDB in practical situations. Methods Sirloins from 48 Hanwoo cows were frozen (Control, 2 days postmortem) or dry-aged for 28 days using the different aging methods and analyzed for chemical composition, total aerobic bacterial count, shear force, inosine 5′-monophosphate (IMP) and free amino acid content, and sensory properties. Results The difference in chemical composition, total aerobic bacterial count, shear force, IMP, and total free amino acid content were negligible among the 3 dry-aged groups. The SD and SDB showed statistically similar tenderness, flavor, and overall acceptability relative to TD. However, SDB had a relatively higher saleable yield. Conclusion Both SD and SDB can successfully substitute for TD. However, SDB would be the best option for simplified dry-aging of low-marbled beef with a relatively high saleable yield. PMID:28728384

Analysis of low-marbled Hanwoo cow meat aged with different dry-aging methods.

PubMed

Lee, Hyun Jung; Choe, Juhui; Kim, Kwan Tae; Oh, Jungmin; Lee, Da Gyeom; Kwon, Ki Moon; Choi, Yang Il; Jo, Cheorun

2017-12-01

Different dry-aging methods [traditional dry-aging (TD), simplified dry-aging (SD), and SD in an aging bag (SDB)] were compared to investigate the possible use of SD and/or SDB in practical situations. Sirloins from 48 Hanwoo cows were frozen (Control, 2 days postmortem) or dry-aged for 28 days using the different aging methods and analyzed for chemical composition, total aerobic bacterial count, shear force, inosine 5'-monophosphate (IMP) and free amino acid content, and sensory properties. The difference in chemical composition, total aerobic bacterial count, shear force, IMP, and total free amino acid content were negligible among the 3 dry-aged groups. The SD and SDB showed statistically similar tenderness, flavor, and overall acceptability relative to TD. However, SDB had a relatively higher saleable yield. Both SD and SDB can successfully substitute for TD. However, SDB would be the best option for simplified dry-aging of low-marbled beef with a relatively high saleable yield.

Zircon from charnockite gneiss, charnockite, and leucosome of migmatite in the Nimnyr Block of the Aldan Shield

NASA Astrophysics Data System (ADS)

Glebovitsky, V. A.; Sedova, I. S.; Berezhnaya, N. G.; Skublov, S. G.; Samorukova, L. M.

2015-12-01

The microgeochemistry of zircon was studied in three samples: charnockite gneiss (1594), charnockite (1594a), and migmatite leucosome Lc4 (1594c). Prismatic (Zrn I) and oval (Zrn II) zircon morphotypes are distinguished in the first two samples. Most zircon grains consist of two-phase cores and overgrowth rims variable in thickness. The average weighted concordant U-Pb age of Zrn II cores from charnockite gneiss is 2436 ± 10 Ma. The concordant ages of Zrn I and Zrn II cores from charnockite are 2402 ± 16 Ma and 2453 ± 14 Ma, respectively. Some overgrowth rims are 1.9-2.1 Ga in age. In leucosome Lc4, all measured prismatic zircon crystals yielded a discordant age of 1942 ± 11 Ma (the upper intersection of discordia with concordia). These zircons are strongly altered and anomalously enriched in U and Th. Zrn I grains are enriched relative to Zrn II in REE, Li, Ca, Sr, Ba, Hf, Th, and U. Zrn I is considered to be a product of melt crystallization or subsolidus recrystallization in the presence of melt. Zrn II is relict or crystallizing from melt and then partly fused again. Zrn I from charnockite gneiss and especially from charnockite are markedly altered and have a more discordant age than Zrn II. This is probably related to concentration of fluid in the residual melt left after zircon crystallization.

[Validity and reliability of the screening questionnaire for geriatric depression used in the Mexican Health and Age Study].

PubMed

Aguilar-Navarro, Sara Gloria; Fuentes-Cantú, Alejandro; Avila-Funes, José Alberto; García-Mayo, Emilio José

2007-01-01

To assess the validity and reliability of a geriatric depression questionnaire used in the Mexican Health and Age Study (MHAS). The study was conducted at the Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán (INCMNSZ) clinic from May 2005 to March 2006. This depression screening nine-item questionnaire was validated using the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) (fourth revised version) and Yesavage's 15-item Geriatric Depression Scale (GDS-15) criteria. The instrument belongs to the MHAS, a prospective panel study of health and aging in Mexico. A total of 199 subjects 65 years of age and older participated in the validation process (median age= 79.5 years). MHAS questionnaire result was significantly correlated to the clinical depression diagnosis (p<0.001) and to the GDS-15 score (p<0.001). Internal consistency was adequate (alpha coefficient: 0.74). The cutoff point > or = 5/9 points yielded an 80.7% and 68.7% sensitivity and specificity respectively. The fidelity for the test retest was excellent (intra-class correlation coefficient= 0.933). Finally, the Bland and Altman agreement points indicated a difference 0.22 percent points between test retest. The MHAS questionnaire is valid and trustworthy, and allows screening in the research field for the presence of depression in the elderly.

Fresh and Stored Pollen From Slash and Loblolly Pines Compared For Seed Yields

Treesearch

John F. Kraus; Davie L. Hunt

1970-01-01

Seed yields showed no consistent differences between fresh and stored pollen from 8 years of controlled pollination on slash pine and 4 years on loblolly pine. Collection of male strobili at the proper stage of pollen maturity was an important factor in obtaining good seed yields from stored pollen. Criteria are described which were useful in determining when to...

The Cannery Formation--Devonian to Early Permian arc-marginal deposits within the Alexander Terrane, Southeastern Alaska

USGS Publications Warehouse

Karl, Susan M.; Layer, Paul W.; Harris, Anita G.; Haeussler, Peter J.; Murchey, Benita L.

2011-01-01

The Cannery Formation consists of green, red, and gray ribbon chert, siliceous siltstone, graywacke-chert turbidites, and volcaniclastic sandstone. Because it contains early Permian fossils at and near its type area in Cannery Cove, on Admiralty Island in southeastern Alaska, the formation was originally defined as a Permian stratigraphic unit. Similar rocks exposed in Windfall Harbor on Admiralty Island contain early Permian bryozoans and brachiopods, as well as Mississippian through Permian radiolarians. Black and green bedded chert with subordinate lenses of limestone, basalt, and graywacke near Kake on Kupreanof Island was initially correlated with the Cannery Formation on the basis of similar lithology but was later determined to contain Late Devonian conodonts. Permian conglomerate in Keku Strait contains chert cobbles inferred to be derived from the Cannery Formation that yielded Devonian and Mississippian radiolarians. On the basis of fossils recovered from a limestone lens near Kake and chert cobbles in the Keku Strait area, the age of the Cannery Formation was revised to Devonian and Mississippian, but this revision excludes rocks in the type locality, in addition to excluding bedded chert on Kupreanof Island east of Kake that contains radiolarians of Late Pennsylvanian and early Permian age. The black chert near Kake that yielded Late Devonian conodonts is nearly contemporaneous with black chert interbedded with limestone that also contains Late Devonian conodonts in the Saginaw Bay Formation on Kuiu Island. The chert cobbles in the conglomerate in Keku Strait may be derived from either the Cannery Formation or the Saginaw Bay Formation and need not restrict the age of the Cannery Formation, regardless of their source. The minimum age of the Cannery Formation on both Admiralty Island and Kupreanof Island is constrained by the stratigraphically overlying fossiliferous Pybus Formation, of late early and early late Permian age. Because bedded radiolarian cherts on both Admiralty and Kupreanof Islands contain radiolarians as young as Permian, the age of the Cannery Formation is herein extended to Late Devonian through early Permian, to include the early Permian rocks exposed in its type locality. The Cannery Formation is folded and faulted, and its stratigraphic thickness is unknown but inferred to be several hundred meters. The Cannery Formation represents an extended period of marine deposition in moderately deep water, with slow rates of deposition and limited clastic input during Devonian through Pennsylvanian time and increasing argillaceous, volcaniclastic, and bioclastic input during the Permian. The Cannery Formation comprises upper Paleozoic rocks in the Alexander terrane of southeastern Alaska. In the pre-Permian upper Paleozoic, the tectonic setting of the Alexander terrane consisted of two or more evolved oceanic arcs. The lower Permian section is represented by a distinctive suite of rocks in the Alexander terrane, which includes sedimentary and volcanic rocks containing early Permian fossils, metamorphosed rocks with early Permian cooling ages, and intrusive rocks with early Permian cooling ages, that form discrete northwest-trending belts. After restoration of 180 km of dextral displacement of the Chilkat-Chichagof block on the Chatham Strait Fault, these belts consist, from northeast to southwest, of (1) bedded chert, siliceous argillite, volcaniclastic turbidites, pillow basalt, and limestone of the Cannery Formation and the Porcupine Slate of Gilbert and others (1987); (2) greenschist-facies Paleozoic metasedimentary and metavolcanic rocks that have Permian cooling ages; (3) silty limestone and calcareous argillite interbedded with pillow basalt and volcaniclastic rocks of the Halleck Formation and the William Henry Bay area; and (4) intermediate-composition and syenitic plutons. These belts correspond to components of an accretionary complex, contemporary metamorphic rocks, forearc-basin deposits,

Age of the Mono Lake excursion and associated tephra

USGS Publications Warehouse

Benson, L.; Liddicoat, J.; Smoot, J.; Sarna-Wojcicki, A.; Negrini, R.; Lund, S.

2003-01-01

The Mono Lake excursion (MLE) is an important time marker that has been found in lake and marine sediments across much of the Northern Hemisphere. Dating of this event at its type locality, the Mono Basin of California, has yielded controversial results with the most recent effort concluding that the MLE may actually be the Laschamp excursion (Earth Planet. Sci. Lett. 197 (2002) 151). We show that a volcanic tephra (Ash #15) that occurs near the midpoint of the MLE has a date (not corrected for reservoir effect) of 28,620 ?? 300 14C yr BP (??? 32,400 GISP2 yr BP) in the Pyramid Lake Basin of Nevada. Given the location of Ash #15 and the duration of the MLE in the Mono Basin, the event occurred between 31,500 and 33,300 GISP2 yr BP, an age range consistent with the position and age of the uppermost of two paleointensity minima in the NAPIS-75 stack that has been associated with the MLE (Philos. Trans. R. Soc. London Ser. A 358 (2000) 1009). The lower paleointensity minimum in the NAPIS-75 stack is considered to be the Laschamp excursion (Philos. Trans. R. Soc. London Ser. A 358 (2000) 1009).

A review and rationale for studying the cardiovascular effects of drinking water arsenic in women of reproductive age

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwok, Richard K., E-mail: rkwok@rti.org

2007-08-01

Drinking water arsenic has been shown to be associated with a host of adverse health outcomes at exposure levels > 300 {mu}g of As/L. However, the results are not consistent at exposures below this level. We have reviewed selected articles that examine the effects of drinking water arsenic on cardiovascular outcomes and present a rationale for studying these effects on women of reproductive age, and also over the course of pregnancy when they would potentially be more susceptible to adverse cardiovascular and reproductive outcomes. It is only recently that reproductive effects have been linked to drinking water arsenic. However, theremore » is a paucity of information about the cardiovascular effects of drinking water arsenic on women of reproductive age. Under the cardiovascular challenge of pregnancy, we hypothesize that women with a slightly elevated exposure to drinking water arsenic may exhibit adverse cardiovascular outcomes at higher rates than in the general population. Studying sensitive clinical and sub-clinical indicators of disease in susceptible sub-populations may yield important information about the potentially enormous burden of disease related to low-level drinking water arsenic exposure.« less

Using the gene ontology for microarray data mining: a comparison of methods and application to age effects in human prefrontal cortex.

PubMed

Pavlidis, Paul; Qin, Jie; Arango, Victoria; Mann, John J; Sibille, Etienne

2004-06-01

One of the challenges in the analysis of gene expression data is placing the results in the context of other data available about genes and their relationships to each other. Here, we approach this problem in the study of gene expression changes associated with age in two areas of the human prefrontal cortex, comparing two computational methods. The first method, "overrepresentation analysis" (ORA), is based on statistically evaluating the fraction of genes in a particular gene ontology class found among the set of genes showing age-related changes in expression. The second method, "functional class scoring" (FCS), examines the statistical distribution of individual gene scores among all genes in the gene ontology class and does not involve an initial gene selection step. We find that FCS yields more consistent results than ORA, and the results of ORA depended strongly on the gene selection threshold. Our findings highlight the utility of functional class scoring for the analysis of complex expression data sets and emphasize the advantage of considering all available genomic information rather than sets of genes that pass a predetermined "threshold of significance."

The Younger Dryas phase of Great Salt Lake, Utah, USA

USGS Publications Warehouse

Oviatt, Charles G.; Miller, D.M.; McGeehin, J.P.; Zachary, C.; Mahan, S.

2005-01-01

Field investigations at the Public Shooting Grounds (a wildlife-management area on the northeastern shore of Great Salt Lake) and radiocarbon dating show that the Great Salt Lake rose to the Gilbert shoreline sometime between 12.9 and 11.2 cal ka. We interpret a ripple-laminated sand unit exposed at the Public Shooting Grounds, and dated to this time interval, as the nearshore sediments of Great Salt Lake deposited during the formation of the Gilbert shoreline. The ripple-laminated sand is overlain by channel-fill deposits that overlap in age (11.9-11.2 cal ka) with the sand, and by wetland deposits (11.1 to 10.5 cal ka). Consistent accelerator mass spectrometry radiocarbon ages were obtained from samples of plant fragments, including those of emergent aquatic plants, but mollusk shells from spring and marsh deposits yielded anomalously old ages, probably because of a variable radiocarbon reservoir effect. The Bonneville basin was effectively wet during at least part of the Younger Dryas global-cooling interval, however, conflicting results from some Great Basin locations and proxy records indicate that the regional effects of Younger Dryas cooling are still not well understood. ?? 2005 Elsevier B.V. All rights reserved.

Reducing Error Bars through the Intercalibration of Radioisotopic and Astrochronologic Time Scales for the Cenomanian/Turonian Boundary Interval, Western Interior Basin, USA

NASA Astrophysics Data System (ADS)

Meyers, S. R.; Siewert, S. E.; Singer, B. S.; Sageman, B. B.; Condon, D. J.; Obradovich, J. D.; Jicha, B.; Sawyer, D. A.

2010-12-01

We develop a new intercalibrated astrochronologic and radioisotopic time scale for the Cenomanian/Turonian (C/T) boundary interval near the GSSP in Colorado, where orbitally-influenced rhythmic strata host bentonites that contain sanidine and zircon suitable for 40Ar/39Ar and U-Pb dating. This provides a rare opportunity to directly intercalibrate two independent radioisotopic chronometers against an astrochronologic age model. We present paired 40Ar/39Ar and U-Pb ages from four bentonites spanning the Vascoceras diartianum to Pseudaspidoceras flexuosum biozones, utilizing both newly collected material and legacy sanidine samples of Obradovich (1993). Full 2σ uncertainties (decay constant, standard age, analytical sources) for the 40Ar/39Ar ages, using a weighted mean of 33-103 concordant age determinations and an age of 28.201 Ma for Fish Canyon sanidine (FCs), range from ±0.15 to 0.19 Ma, with ages from 93.67 to 94.43 Ma. The traditional FCs age of 28.02 Ma yields ages from 93.04 to 93.78 Ma with full uncertainties of ±1.58 Ma. Using the ET535 tracer, single zircon CA-TIMS 206Pb/238U ages determined from each bentonite record a range of ages (up to 2.1 Ma), however, in three of the four bentonites the youngest single crystal ages are statistically indistinguishable from the 40Ar/39Ar ages calculated relative to 28.201 Ma FCs, supporting this calibration. Using the new radioisotopic data and published astrochronology (Sageman et al., 2006) we develop an integrated C/T boundary time scale using a Bayesian statistical approach that builds upon the strength of each geochronologic method. Whereas the radioisotopic data provide an age with a well-defined uncertainty for each bentonite, the orbital time scale yields a more highly resolved estimate of the duration between stratigraphic horizons, including the radioisotopically dated beds. The Bayesian algorithm yields a C/T time scale that is statistically compatible with the astrochronologic and radioisotopic data, but with smaller uncertainty than either method could achieve alone. The results firmly anchor the floating orbital time scale and yield astronomically-recalibrated radioisotopic ages with full uncertainties that approach the EARTHTIME goal of permil resolution.

OSL dating of a Pleistocene maar: Birket Ram, the Golan heights

USGS Publications Warehouse

Shaanan, U.; Porat, N.; Navon, O.; Weinberger, R.; Calvert, A.; Weinstein, Y.

2011-01-01

Direct dating of maars and their phreatomagmatic deposits is difficult due to the dominance of lithic (host rock) fragments and glassy particles of the juvenile magma. In this paper we demonstrate that optically stimulated luminescence (OSL) dating can be successfully used for age determination of phreatomagmatic deposits. We studied the tuff deposit of Birket Ram, a basanitic maar located at the northern edge of the Golan heights on the western Arabian plate. The maar is underlain by a thick section of Pleistocene basalts, and currently hosts a small lake. It is filled by approximately 90m of lacustrine sediments with radiocarbon ages extrapolated to 108ka at the base. OSL was applied to quartz grains extracted from tuffs and paleosols in order to set the time frame of the phreatomagmatism at the site. A maximum age constraint of 179??13ka was determined for a paleosol that underlies the maar ejecta. Quartz grains from two layers in the tuff section yielded a direct age of 129??6ka for the phreatomagmatic eruption. A younger age of 104??7ka, which was determined for a tuff layer underlying a basaltic flow, was attributed to thermal resetting during the lava emplacement. This was confirmed by an 40Ar/39Ar age of 101??3ka determined on the overlying basalt. The internal consistency of the OSL ages and the agreement with the 40Ar/39Ar age determination as well as with previous estimates demonstrates the potential of OSL for maar dating. ?? 2010 Elsevier B.V.

Cropping system diversification for food production in Mindanao rubber plantations: a rice cultivar mixture and rice intercropped with mungbean

PubMed Central

Elazegui, Francisco; Duque, Jo-Anne Lynne Joy E.; Mundt, Christopher C.; Vera Cruz, Casiana M.

2017-01-01

Including food production in non-food systems, such as rubber plantations and biofuel or bioenergy crops, may contribute to household food security. We evaluated the potential for planting rice, mungbean, rice cultivar mixtures, and rice intercropped with mungbean in young rubber plantations in experiments in the Arakan Valley of Mindanao in the Philippines. Rice mixtures consisted of two- or three-row strips of cultivar Dinorado, a cultivar with higher value but lower yield, and high-yielding cultivar UPL Ri-5. Rice and mungbean intercropping treatments consisted of different combinations of two- or three-row strips of rice and mungbean. We used generalized linear mixed models to evaluate the yield of each crop alone and in the mixture or intercropping treatments. We also evaluated a land equivalent ratio for yield, along with weed biomass (where Ageratum conyzoides was particularly abundant), the severity of disease caused by Magnaporthe oryzae and Cochliobolus miyabeanus, and rice bug (Leptocorisa acuta) abundance. We analyzed the yield ranking of each cropping system across site-year combinations to determine mean relative performance and yield stability. When weighted by their relative economic value, UPL Ri-5 had the highest mean performance, but with decreasing performance in low-yielding environments. A rice and mungbean intercropping system had the second highest performance, tied with high-value Dinorado but without decreasing relative performance in low-yielding environments. Rice and mungbean intercropped with rubber have been adopted by farmers in the Arakan Valley. PMID:28194318

Optimizing Dense Plasma Focus Neutron Yields With Fast Gas Jets

NASA Astrophysics Data System (ADS)

McMahon, Matthew; Stein, Elizabeth; Higginson, Drew; Kueny, Christopher; Link, Anthony; Schmidt, Andrea

2017-10-01

We report a study using the particle-in-cell code LSP to perform fully kinetic simulations modeling dense plasma focus (DPF) devices with high density gas jets on axis. The high-density jets are modeled in the large-eddy Navier-Stokes code CharlesX, which is suitable for modeling both sub-sonic and supersonic gas flow. The gas pattern, which is essentially static on z-pinch time scales, is imported from CharlesX to LSP for neutron yield predictions. Fast gas puffs allow for more mass on axis while maintaining the optimal pressure for the DPF. As the density of a subsonic jet increases relative to the background fill, we find the neutron yield increases, as does the variability in the neutron yield. Introducing perturbations in the jet density via super-sonic flow (also known as Mach diamonds) allow for consistent seeding of the m =0 instability leading to more consistent ion acceleration and higher neutron yields with less variability. Jets with higher on axis density are found to have the greatest yield. The optimal jet configuration and the necessary jet conditions for increasing neutron yield and reducing yield variability are explored. Simulations of realistic jet profiles are performed and compared to the ideal scenario. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and supported by the Laboratory Directed Research and Development Program (15-ERD-034) at LLNL.

Mesoproterozoic evolution of the Río de la Plata Craton in Uruguay: at the heart of Rodinia?

NASA Astrophysics Data System (ADS)

Gaucher, Claudio; Frei, Robert; Chemale, Farid; Frei, Dirk; Bossi, Jorge; Martínez, Gabriela; Chiglino, Leticia; Cernuschi, Federico

2011-04-01

Mesoproterozoic volcanosedimentary units and tectonic events occurring in the Río de la Plata Craton (RPC) are reviewed. A belt consisting of volcanosedimentary successions exhibiting greenschist-facies metamorphism is exposed in the eastern RPC (Nico Pérez Terrane) in Uruguay. The Parque UTE Group consists of basic volcanics and gabbros at the base (1,492 ± 4 Ma, U-Pb on zircon), carbonates in its middle part and interbedded carbonates, shales and acid volcanics (1,429 ± 21 Ma, U-Pb on zircon) at the top. The Mina Verdún Group is made up of rhyolites and acid pyroclastics at its base and top, and Conophyton-bearing limestones and massive dolostones in the middle. A U-Pb LA-ICP MS zircon age of 1,433 ± 6 Ma is reported here for lapilli-tuffs at the base of the Mina Verdún Group (Cerro de las Víboras Formation). This age shows that the Mina Verdún Group immediately postdates the Parque UTE Group, a fact supported by carbon isotope chemostratigraphy. Both units were deformed and metamorphosed between 1.25 and 1.20 Ga, as shown by K-Ar and Ar-Ar ages. This tectonic event affected most of the RPC and led to the accretion of the Nico Pérez Terrane to the remainder of the RPC along the Sarandí del Yí megashear. We report a U-Pb LA-ICP MS zircon age (upper intercept) of 3,096 ± 45 Ma for metatonalites of the La China Complex (Nico Pérez Terrane), which yield a lower intercept age of 1,252 Ma. A proto-Andean, Mesoproterozoic belt is envisaged to account for abundant Mesoproterozoic detrital zircon ages occurring in Ediacaran sandstones of the RPC. If the RPC is fringed at both sides by Mesoproterozoic, Grenville-aged belts it is likely that it occupied a rather central position in Rodinia. A possible location between Laurentia and the Kalahari Craton, and to the south of Amazonia, is suggested.

Shocked monazite chronometry: integrating microstructural and in situ isotopic age data for determining precise impact ages

NASA Astrophysics Data System (ADS)

Erickson, Timmons M.; Timms, Nicholas E.; Kirkland, Christopher L.; Tohver, Eric; Cavosie, Aaron J.; Pearce, Mark A.; Reddy, Steven M.

2017-03-01

Monazite is a robust geochronometer and occurs in a wide range of rock types. Monazite also records shock deformation from meteorite impact but the effects of impact-related microstructures on the U-Th-Pb systematics remain poorly constrained. We have, therefore, analyzed shock-deformed monazite grains from the central uplift of the Vredefort impact structure, South Africa, and impact melt from the Araguainha impact structure, Brazil, using electron backscatter diffraction, electron microprobe elemental mapping, and secondary ion mass spectrometry (SIMS). Crystallographic orientation mapping of monazite grains from both impact structures reveals a similar combination of crystal-plastic deformation features, including shock twins, planar deformation bands and neoblasts. Shock twins were documented in up to four different orientations within individual monazite grains, occurring as compound and/or type one twins in (001), (100), ( 10bar{1} ), {110}, { 212 }, and type two (irrational) twin planes with rational shear directions in [0bar{1}bar{1}] and [bar{1}bar{1}0]. SIMS U-Th-Pb analyses of the plastically deformed parent domains reveal discordant age arrays, where discordance scales with increasing plastic strain. The correlation between discordance and strain is likely a result of the formation of fast diffusion pathways during the shock event. Neoblasts in granular monazite domains are strain-free, having grown during the impact events via consumption of strained parent grains. Neoblastic monazite from the Inlandsee leucogranofels at Vredefort records a 207Pb/206Pb age of 2010 ± 15 Ma (2 σ, n = 9), consistent with previous impact age estimates of 2020 Ma. Neoblastic monazite from Araguainha impact melt yield a Concordia age of 259 ± 5 Ma (2 σ, n = 7), which is consistent with previous impact age estimates of 255 ± 3 Ma. Our results demonstrate that targeting discrete microstructural domains in shocked monazite, as identified through orientation mapping, for in situ U-Th-Pb analysis can date impact-related deformation. Monazite is, therefore, one of the few high-temperature geochronometers that can be used for accurate and precise dating of meteorite impacts.

Application of Lamendin's adult dental aging technique to a diverse skeletal sample.

PubMed

Prince, Debra A; Ubelaker, Douglas H

2002-01-01

Lamendin et al. (1) proposed a technique to estimate age at death for adults by analyzing single-rooted teeth. They expressed age as a function of two factors: translucency of the tooth root and periodontosis (gingival regression). In their study, they analyzed 306 singled rooted teeth that were extracted at autopsy from 208 individuals of known age at death, all of whom were considered as having a French ancestry. Their sample consisted of 135 males, 73 females, 198 whites, and 10 blacks. The sample ranged in age from 22 to 90 years of age. By using a simple formulae (A = 0.18 x P + 0.42 x T + 25.53, where A = Age in years, P = Periodontosis height x 100/root height, and T = Transparency height x 100/root height), Lamendin et al. were able to estimate age at death with a mean error of +/- 10 years on their working sample and +/- 8.4 years on a forensic control sample. Lamendin found this technique to work well with a French population, but did not test it outside of that sample area. This study tests the accuracy of this adult aging technique on a more diverse skeletal population, the Terry Collection housed at the Smithsonian's National Museum of Natural History. Our sample consists of 400 teeth from 94 black females, 72 white females, 98 black males, and 95 white males, ranging from 25 to 99 years. Lamendin's technique was applied to this sample to test its applicability to a population not of French origin. Providing results from a diverse skeletal population will aid in establishing the validity of this method to be used in forensic cases, its ideal purpose. Our results suggest that Lamendin's method estimates age fairly accurately outside of the French sample yielding a mean error of 8.2 years, standard deviation 6.9 years, and standard error of the mean 0.34 years. In addition, when ancestry and sex are accounted for, the mean errors are reduced for each group (black females, white females, black males, and white males). Lamendin et al. reported an inter-observer error of 9+/-1.8 and 10+/-2 sears from two independent observers. Forty teeth were randomly remeasured from the Terry Collection in order to assess an intra-observer error. From this retest, an intra-observer error of 6.5 years was detected.

Enhanced yield of chromosome aberrations after CT examinations in paediatric patients.

PubMed

Stephan, G; Schneider, K; Panzer, W; Walsh, L; Oestreicher, U

2007-05-01

To determine whether computed tomography (CT) could enhance the chromosome aberration yields in paediatric patients. Blood samples were taken before and after CT scans from 10 children for whom the medical justifications for CT examinations were accidental injuries and not diseases as investigated in earlier studies. Chromosome analysis was carried out in lymphocytes by fluorescence plus Giemsa (FPG) staining exclusively in metaphases of the first cell cycle in vitro. The mean blood dose of the 10 children was about 12.9 mGy which was determined by a newly developed dose estimation. Based on more than 20,000 analyzed cells it was found that after CT examination the frequencies of dicentrics (dic) and excess acentric fragments (ace) in lymphocytes were significantly increased. By subdividing the children into two age groups, those with an age from 0.4 years to 9 years and from 10 - 15 years, it became obvious that the observed increase in chromosome aberrations was mainly contributed by the younger age group. In this group the frequency of dicentrics was significantly increased whereas in the older group the observed increase was not significant. Our results demonstrate that CT examinations enhance the dicentrics yields in peripheral lymphocytes of children aged up to 15 years. Since in particular significantly increased dicentric yields could be observed in children with an age from 0.4 - 9 years, it can be assumed that children younger than 10 years may be more radiation sensitive than older subjects.

Re-Os and Lu-Hf isotopic constraints on the formation and age of mantle pyroxenites from the Bohemian Massif

NASA Astrophysics Data System (ADS)

Ackerman, Lukáš; Bizimis, Michael; Haluzová, Eva; Sláma, Jiří; Svojtka, Martin; Hirajima, Takao; Erban, Vojtěch

2016-07-01

We report on the Lu-Hf and Re-Os isotope systematics of a well-characterized suite of spinel and garnet pyroxenites from the Gföhl Unit of the Bohemian Massif (Czech Republic, Austria). Lu-Hf mineral isochrons of three pyroxenites yield undistinguishable values in the range of 336-338 Ma. Similarly, the slope of Re-Os regression for most samples yields an age of 327 ± 31 Ma. These values overlap previously reported Sm-Nd ages on pyroxenites, eclogites and associated peridotites from the Gföhl Unit, suggesting contemporaneous evolution of all these HT-HP rocks. The whole-rock Hf isotopic compositions are highly variable with initial εHf values ranging from - 6.4 to + 66. Most samples show a negative correlation between bulk rock Sm/Hf and εHf and, when taking into account other characteristics (e.g., high 87Sr/86Sr), this may be explained by the presence of recycled oceanic sediments in the source of the pyroxenite parental melts. A pyroxenite from Horní Kounice has decoupled Hf-Nd systematics with highly radiogenic initial εHf of + 66 for a given εNd of + 7.8. This decoupling is consistent with the presence of a melt derived from a depleted mantle component with high Lu/Hf. Finally, one sample from Bečváry plots close to the MORB field in Hf-Nd isotope space consistent with its previously proposed origin as metamorphosed oceanic gabbro. Some of the websterites and thin-layered pyroxenites have variable, but high Os concentrations paralleled by low initial γOs. This reflects the interaction of the parental pyroxenitic melts with a depleted peridotite wall rock. In turn, the radiogenic Os isotope compositions observed in most pyroxenite samples is best explained by mixing between unradiogenic Os derived from peridotites and a low-Os sedimentary precursor with highly radiogenic 187Os/188Os. Steep increase of 187Os/188Os at nearly uniform 187Re/188Os found in a few pyroxenites may be connected with the absence of primary sulfides, but the presence of minor late stage sulfide-bearing veinlets likely associated with HT-HP metamorphism at crustal conditions.

Dating the Duration and Termination of Sinistral Shear in the Western Tauern Window: Implications for Indentation and Exhumation in the Eastern Alps

NASA Astrophysics Data System (ADS)

Schneider, Susanne; Hammerschmidt, Konrad; Rosenberg, Claudio Luca

2010-05-01

The internal structure of the Tauern Window (TW) consists of parallel sets of upright antiforms, striking ENE in the west and ESE in the east. The long axes of the upright folds are parallel to shear zones (SZ), which are generally sinistral in the west and dextral in the east. The formation of these structures has been interpreted as the result of a coeval, conjugate system, forming in response to south-Alpine indentation (Rosenberg et al., 2004), or as a change in the regional shortening direction through time (Polinski and Eisbacher, 1992; Neubauer et al., 2000; Mancktelow et al., 2001). The latter models suggested an Oligocene age for sinistral displacements, followed by Miocene dextral ones. Therefore, determining the timing of these different shear zones is a key to understand the tectonic significance of the structures described above. We analysed the kinematics and determined the formation age of the mylonitic foliation of two sinistral shear zones in the western TW (Ahorn SZ, Olperer SZ). In addition to left lateral displacements, kinematic indicators in the YZ plane for both shear zones point to differential vertical displacements, namely S-side up. We performed absolute age determinations of deformation by dating syn- and on post-kinematically grown minerals, the latter overprinting the former ones microstructurally on the microscopic scale. For this purpose we selected syn-kinematic phengites of mylonites and ultra-mylonites from shear bands, strain caps and also from overprinting statically grown phengites overprinting the mylonitic foliation. The Ar/Ar In-situ UV-laser ablation method was applied using a noble gas mass spectrometer. For comparison micas of an undeformed host rock were also dated using the same method. The obtained age values of syn-kinematic phengites vary between 12-24 Ma. This age variation is commonly found within single grains. Postkinematic, phengites overgrowing the syn-kinematic grains yield the youngest age values, namely 5-12 Ma. We observe a systematic relationship between the ages of the postkinematic grains and the age spread of the syn-kinematic ones. The age of the post-kinematic grains always coincides with the youngest age determined within the syn-kinematic grains. We interpret this relationship as indicating that the growth of post-kinematic minerals followed almost instantaneously the termination of deformation. As a consequence, the age of phengites overprinting the mylonitic foliation yields a precise age for the termination of deformation. The spread in age variation of phengites goes together with a spread in Si content, consequently the postkinematic phengites have a higher Si content compared to the overprinted syn-kinematic ones. Therefore the metamorphic pressure conditions of the post-kinematic phengites were lower, indicating continuous deformation during exhumation within a time interval of approximately 12 Ma. We interpret these ages as formation ages during or after shearing, respectively. Muscovite blasts of the undeformed sample yield age values varying between 22 and 34 Ma. We interpret these ages as cooling ages, following the metamorphic peak temperatures. To conclude, sinistral shear in the western TW started at least 24 Ma ago and terminated at 12 Ma. Therefore, these shear zones do not predate dextral displacements or lateral extrusion within the eastern Tauern sub-dome, which are also Miocene (Inger & Cliff, 1994, Frisch et al., 1998, Glodny et al., 2008). This conclusion suggests that they formed as part of an orogen-scale conjugate system, accommodating Miocene shortening due to South-Alpine indentation. Since these shear zones are transpressive, showing a component of vertical displacement, their age may also constrain exhumation of the Tauern dome.

The Impact of Age on Quality Measure Adherence in Colon Cancer

PubMed Central

Steele, Scott R.; Chen, Steven L.; Stojadinovic, Alexander; Nissan, Aviram; Zhu, Kangmin; Peoples, George E.; Bilchik, Anton

2012-01-01

BACKGROUND Recently lymph node yield (LNY) has been endorsed as a quality measure of CC resection adequacy. It is unclear whether this measure is relevant to all ages. We hypothesized that total lymph node yield (LNY) is negatively correlated with increasing age and overall survival (OS). STUDY DESIGN The Surveillance, Epidemiology and End Results (SEER) database was queried for all non-metastatic CC patients diagnosed from 1992–2004 (n=101,767), grouped by age (<40, 41–45, 46–50, and in 5-year increments until 86+ years). Proportions of patients meeting the 12 LNY minimum criterion were determined in each age group, and analyzed with multivariate linear regression adjusting for demographics and AJCC 6th Edition stage. Overall survival (OS) comparisons in each age category were based on the guideline of 12 LNY. RESULTS Mean LNY decreased with increasing age (18.7 vs. 11.4 nodes/patient, youngest vs. oldest group, P<0.001). The proportion of patients meeting the 12 LNY criterion also declined with each incremental age group (61.9% vs. 35.2% compliance, youngest vs. oldest, P<0.001). Multivariate regression demonstrated a negative effect of each additional year in age and log (LNY) with coefficient of −0.003 (95% CI −0.003 to −0.002). When stratified by age and nodal yield using the 12 LNY criterion, OS was lower for all age groups in Stage II CC with <12LNY, and each age group over 60 years with <12LNY for Stage III CC (P<0.05). CONCLUSIONS Every attempt to adhere to proper oncological principles should be made at time of CC resection regardless of age. The prognostic significance of the 12 LN minimum criterion should be applied even to elderly CC patients. PMID:21601492

The Nolans Bore rare-earth element-phosphorus-uranium mineral system: geology, origin and post-depositional modifications

NASA Astrophysics Data System (ADS)

Huston, David L.; Maas, Roland; Cross, Andrew; Hussey, Kelvin J.; Mernagh, Terrence P.; Fraser, Geoff; Champion, David C.

2016-08-01

Nolans Bore is a rare-earth element (REE)-U-P fluorapatite vein deposit hosted mostly by the ~1805 Ma Boothby Orthogneiss in the Aileron Province, Northern Territory, Australia. The fluorapatite veins are complex, with two stages: (1) massive to granular fluorapatite with inclusions of REE silicates, phosphates and (fluoro)carbonates, and (2) calcite-allanite with accessory REE-bearing phosphate and (fluoro)carbonate minerals that vein and brecciate the earlier stage. The veins are locally accompanied by narrow skarn-like (garnet-diopside-amphibole) wall rock alteration zones. SHRIMP Th-Pb analyses of allanite yielded an age of 1525 ± 18 Ma, interpreted as the minimum age of mineralisation. The maximum age is provided by a ~1550 Ma SHRIMP U-Pb age for a pegmatite that predates the fluorapatite veins. Other isotopic systems yielded ages from ~1443 to ~345 Ma, implying significant post-depositional isotopic disturbance. Calculation of initial ɛNd and 87Sr/86Sr at 1525 Ma and stable isotope data are consistent with an enriched mantle or lower crust source, although post-depositional disturbance is likely. Processes leading to formation of Nolans Bore began with north-dipping subduction along the south margin of the Aileron Province at 1820-1750 Ma, producing a metasomatised, volatile-rich, lithospheric mantle wedge. About 200 million years later, near the end of the Chewings Orogeny, this reservoir and/or the lower crust sourced alkaline low-degree partial melts which passed into the mid- and upper-crust. Fluids derived from these melts, which may have included phosphatic melts, eventually deposited the Nolans Bore fluorapatite veins due to fluid-rock interaction, cooling, depressurisation and/or fluid mixing. Owing to its size and high concentration of Th (2500 ppm), in situ radiogenic heating caused significant recrystallisation and isotopic resetting. The system finally cooled below 300 °C at ~370 Ma, possibly in response to unroofing during the Alice Springs Orogeny. Surface exposure and weathering of fluorapatite produced acidic fluids and intense, near-surface kaolinitised zones that include high-grade, supergene-enriched cheralite-rich ores.

Petrogenesis of Cretaceous volcanic-intrusive complex from the giant Yanbei tin deposit, South China: Implication for multiple magma sources, tin mineralization, and geodynamic setting

NASA Astrophysics Data System (ADS)

Li, Qian; Zhao, Kui-Dong; Lai, Pan-Chen; Jiang, Shao-Yong; Chen, Wei

2018-01-01

The giant Yanbei tin ore deposit is the largest porphyry-type tin deposit in South China. The orebodies are hosted by the granite porphyry in the central part of the Yanbei volcanic basin in southern Jiangxi Province. The Yanbei volcanic-intrusive complex mainly consists of dacitic-rhyolitic volcanic rocks, granite, granite porphyry and diabase dikes. In previous papers, the granite porphyry was considered as subvolcanic rocks, which came from the same single magma chamber with the volcanic rocks. In this study, zircon U-Pb ages and Hf isotope data, as well as whole-rock geochemical and Sr-Nd isotopic compositions of different magmatic units in the Yanbei complex are reported. Geochronologic results show that various magmatic units have different formation ages. The dacite yielded a zircon U-Pb age of 143 ± 1 Ma, and the granite porphyry has the emplacement age of 138 ± 1 Ma. Diabase dikes which represented the final stage of magmatism, yielded a zircon U-Pb age of 128 ± 1 Ma. Distinctive whole rock Sr-Nd and zircon Hf isotopic compositions suggest that these magmatic units were derived from different magma sources. The volcanic rocks were mainly derived from the partial melting of Paleoproterozoic metasedimentary rocks without additions of mantle-derived magma. The granite porphyry has an A-type geochemical affinity, and was derived from remelting of Paleo-Mesoproterozoic crustal source with involvement of a subordinate mantle-derived magma. The granite porphyry is also a typical stanniferous granite with high F (4070-6090 ppm) and Sn (7-39 ppm) contents. It underwent strongly crystal fractionation of plagioclase, K-feldspar, and accessory minerals (like apatite, Fe-Ti oxides), which may contribute to the tin mineralization. The diabase was derived by partial melting of enriched lithospheric mantle which had been metasomatised by slab-derived fluids. The change of magmatic sources reflected an increasing extensional tectonic environment, perhaps induced by slab rollback of subducted paleo-Pacific plate.

Geodynamic Setting of Proterozoic Dyke Swarms of the Leo-Man Craton, West Africa, Based on New U-Pb Dating and Geochemistry

NASA Astrophysics Data System (ADS)

Baratoux, L.; Jessell, M.; Söderlund, U.; Ernst, R. E.; Benoit, M.; Naba, S.; Cournede, C.; Perrouty, S.; Metelka, V.; Yatte, D.; Diallo, D. P.; Ndiaye, P. M.; Dioh, E.; Baratoux, D.

2016-12-01

Over 20 sets of dolerite dykes crosscutting Paleoproterozoic basement in West Africa were distinguished via the interpretation of regional and high-resolution airborne magnetic data available over the West African Craton. Some of the dykes reach over 300 km in length and are considered parts of much larger systems of mafic dyke swarms which form the plumbing system of Large Igneous Provinces (LIPs). Five different dyke swarms in Burkina Faso, Niger, Ghana and Senegal were investigated. In terms of petrography and composition, the mafic dykes correspond to tholeiitic basalts and are typically composed of plagioclase + clinopyroxene ± orthopyroxene ± olivine. They display a doleritic texture of variable grain size. Eleven ID-TIMS U-Pb ages obtained on baddeleyite define five generations of Proterozoic age. The N10 Libiri dyke swarm, found in western Niger, yielded an age of ca. 1790 Ma. The N40 Bassari swarm in Senegal was dated at ca. 1764 Ma, and is potentially linked to the 1790 Ma Libiri swarm, 1400 km away. The 300 by 400 km Korsimoro N100 dyke swarm transects central Burkina Faso and was dated at ca. 1575 Ma. Five ca. 1520 Ma ages were obtained for dykes of the Essakane swarm, three in Burkina Faso, one from Ghana (N130 orientation) and one from Senegal (E-W orientation), and document a large extent (600 km wide and 1500 km long) and short duration of dyke emplacement. The Manso N350 dyke swarm in southern Ghana, which is about 400 km long and about 200 km wide, yields a preliminary age of ca 870 Ma. A mantle plume origin is suggested for these swarms, especially the 1790-1765 Ma Libiri-Bassari swarm and the 1520 Ma Essakane swarms (which have lithosphere-contaminated E-MORB chemistry), whose scale is similar to largest giant radiating swarms (e.g. CAMP and Mackenzie). The 870 Ma Manso swarm has composition closer to OIB, consistent with a plume/hotspot origin. The 1575 Ma Korsimoro swarm has composition between EMORB and NMORB, which suggests a rift setting.

Coppice Sycamore Yields Through 9 Years

Treesearch

Harvey E. Kennedy

1980-01-01

Cutting cycle and spacing did not significantly affect sycamore dry-weight yields from ages 5-9 years (1974-l 978). Longer cutting cycles usually did give higher yields. Dry-weight yields ranged from 2886 lb per acre (3233 kg/ha) per year in the 1 year, 4x5 ft (1.2 x 1.5 m) spacing to 4541 lb (5088 kg/ha) in the 4-year, 4x5 ft s,pacing. Survival averaged 67 percent...

A new test for the assessment of working memory in clinical settings: Validation and norming of a month ordering task.

PubMed

Buekenhout, Imke; Leitão, José; Gomes, Ana A

2018-05-24

Month ordering tasks have been used in experimental settings to obtain measures of working memory (WM) capacity in older/clinical groups based solely on their face validity. We sought to assess the appropriateness of using a month ordering task in other contexts, including clinical settings, as a psychometrically sound WM assessment. To this end, we constructed a month ordering task (ucMOT), studied its reliability (internal consistency and temporal stability), and gathered construct-related and criterion-related validity evidence for its use as a WM assessment. The ucMOT proved to be internally consistent and temporally stable, and analyses of the criterion-related validity evidence revealed that its scores predicted the efficiency of language comprehension processes known to depend crucially on WM resources, namely, processes involved in pronoun interpretation. Furthermore, all ucMOT items discriminated between younger and older age groups; the global scores were significantly correlated with scores on well-established WM tasks and presented lower correlations with instruments that evaluate different (although related) processes, namely, inhibition and processing speed. We conclude that the ucMOT possesses solid psychometric properties. Accordingly, we acquired normative data for the Portuguese population, which we present as a regression-based algorithm that yields z scores adjusted for age, gender, and years of formal education. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Optically stimulated luminescence dating of Holocene alluvial fans, East Anatolian Fault System, Turkey

NASA Astrophysics Data System (ADS)

Dogan, Tamer; Cetin, Hasan; Yegingil, Zehra; Topaksu, Mustafa; Yüksel, Mehmet; Duygun, Fırat; Nur, Necmettin; Yegingil, İlhami

2015-07-01

In this study, the optically stimulated luminescence dating technique was used to determine the time of deposition of alluvial sediment samples from the Türkoğlu-Antakya segment of the East Anatolian Fault System (EAFS) in Turkey. The double-single aliquot regenerative dose protocol on fine grain samples was used to estimate equivalent doses (De). Annual dose rate was computed using elemental concentration of uranium (U) and thorium (Th) determined by using thick-source alpha counting and potassium (K) concentrations using X-ray fluorescence and/or atomic absorption spectroscopy. The environmental dose was measured in situ using α-Al2O3:C chips inside plastic tubes for a year. The two different bulk sediment samples collected from the Islahiye trench yielded ages of 4.54 ± 0.28 and 2.91 ± 0.23 ka. We also obtained a 2.60 ± 0.18 ka age for the alluvial deposit in the Kıranyurdu trench and 2.31 ± 0.14 ka age for an excavation area called Malzeme Ocağı. These ages were consistent with the corresponding calibrated Carbon-14 (14C) ages of the region. The differences between the determined ages were insufficient to clearly distinguish the disturbance event from the effects of bioturbation, biological mixing, or other sources of De variation in the region. They provide a record of alluvial aggradation in the region and may determine undocumented historical earthquake events.

Season of conception is associated with future survival, fertility, and milk yield of Holstein cows.

PubMed

Pinedo, P J; De Vries, A

2017-08-01

Environmental influences during different stages of pregnancy can induce lifelong changes in the structure, physiology, and metabolism of the offspring. Our hypothesis was that season of conception (when the offspring was conceived), associated with heat stress conditions at conception and during the initial stages of embryonic development, affects the lifetime performance and survival of the female offspring after birth. The objective was to analyze the association between month of conception and subsequent survival, fertility, and milk yield in cows maintained on dairy farms in Florida, where the climate during the summer is hot and humid but winters are mild. Initial data consisted of 667,104 Dairy Herd Improvement lactation records from cows calving between 2000 and 2012 in 152 herds. Dates of conception were estimated as birth date minus 280 d. The magnitude of heat stress in each herd was quantified by comparing milk yield during summer and winter. Wood's lactation curves were fitted to adjust milk yields for effects of days in milk, and residuals were obtained for each calendar month. A sine function was fitted on the 12 residuals per farm. The difference between the highest and lowest points on the sine function was termed the seasonality index, a measure of the direct effect of heat stress on milk production. Herds were categorized in 3 levels of seasonality [low (seasonality index values less than the 25th percentile value; <2.84), medium (values within the interquartile range), and high (values greater than the 75th percentile value; >5.22)]. Cows were grouped by their month of conception: summer (July-September) and winter (December-February), and comparisons were performed by parity using logistic regression, ANOVA, and survival analysis. Two models were developed. Model A included the complete population of cows (n = 337,529 lactation records) conceived in winter or summer. Model B included cows (n = 228,257 lactation records) that had parent-average genetic information available to be able to correct for farmer's use of lower genetic merit of sires in summer. Other variables included in the models were month and year of calving, age at first calving, and herd. Models were run per parity group (1, 2, and ≥3). In both models, age at first calving was lower for cows conceived during winter versus summer. The odds (95% confidence interval) of survival to a second calving for cows conceived in winter were 1.21 and 1.15 times the odds of survival for cows conceived in summer for models A and B, respectively. Numbers of days from calving to first breeding and from calving to conception were consistently smaller for winter versus summer months of conception across all parity categories. Milk yields (305 d and by 70 d in milk) were greater for cows conceived in winter versus summer. In conclusion, cows that were conceived in the winter had better subsequent survival and performance than cows that were conceived in the summer. There is evidence that season of conception may have lifelong consequences for the offspring. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Lithostratigraphy, geophysics, biostratigraphy, and strontium-isotope stratigraphy of the surficial aquifer system of eastern Collier County and northern Monroe County, Florida

USGS Publications Warehouse

Weedman, S.D.; Paillet, Frederick L.; Edwards, L.E.; Simmons, K.R.; Scott, T.M.; Wardlaw, B.R.; Reese, R.S.; Blair, J.L.

1999-01-01

In 1997, ten cores were drilled in eastern Collier County and northern Monroe County, within the limits of the Big Cypress National Preserve. These cores represent a continuation of the study of seven cores in western Collier County begun in 1996 and reported in Weedman and others (1997) and Edwards and others (1998). This joint U.S. Geological Survey and Florida Geological Survey project is designed to acquire subsurface geologic and hydrologic data in southwest Florida to extend current ground-water models, thereby expanding the utility of these models for land and water management. In this report we describe the lithostratigraphy, geophysical logging, sedimentological analysis, dinocyst biostratigraphy, and strontium-isotope stratigraphy of these ten cores. The three geophysical logs (natural gamma-ray, induction conductivity, and neutron porosity) assumed to be related to formation lithology and water quality show that a number of clay-rich zones are present in all of the boreholes, and that pore-water conductivity increases with depth. The clay-rich zones are confirmed by visual examination of core material and sedimentological analysis. The relative transmissivity calculated at 10-foot-thick intervals shows that in six of the boreholes, high values are associated with the shallow aquifer in the 0-40 ft interval. Two of the boreholes (the most northerly and the most easterly) showed relatively higher values of transmissivity in permeable zones at or somewhat below 100 ft in depth. Core geology and logs indicate that the deeper aquifers are not more permeable than similar deeper zones in the other boreholes, but rather that the shallow aquifer appears to be less permeable in these two coreholes. The Arcadia (?) Formation was only penetrated in the deepest core where it is late Miocene in age. The Peace River Formation was penetrated in all but the two westernmost cores. It yields a late Miocene age, based on both dinocysts and strontium-isotope stratigraphy. The top is an irregular surface. Age and stratigraphic relations suggest that the upper part of the Peace River and lower part of the unnamed formation are at least partially equivalent laterally. The unnamed formation was recovered in every core. It is thinnest in the northernmost core and thickest to the west. Ages calculated from strontium isotopes range from 6.9 to 4.6 million years ago (late Miocene to early Pliocene). The top of the unnamed formation is deepest to the north and it becomes shallower to the southwest. The Tamiami Formation also was recovered in every core and consistently yields early Pliocene ages; it yields late Pliocene ages near the top in two cores. The age and lateral relations strongly suggest that the lower part of the Tamiami Formation and the upper part of the unnamed formation are lateral facies of each other. The Fort Thompson (?) Formation, Miami Limestone, and undifferentiated siliciclastic sediments and limestone at the very top of the cores were not dated.

Constraints on the Composition and Evolution of the Lunar Crust from Meteorite NWA 3163

NASA Technical Reports Server (NTRS)

McLeod, C. L.; Brandon, A. D.; Fernandes, V. A.; Peslier, A. H.; Lapen, T. J.; Irving, A. J.

2013-01-01

The lunar meteorite NWA 3163 (paired with NWA 4881, 4483) is a ferroan, feldspathic granulitic breccia characterized by pigeonite, augite, olivine, maskelynite and accessory Tichromite, ilmenite and troilite. Bulk rock geochemical signatures indicate the lack of a KREEP- derived component (Eu/Eu* = 3.47), consistent with previously studied lunar granulites and anorthosites. Bulk rock chondrite-normalized signatures are however distinct from the anorthosites and granulites sampled by Apollo missions and are relatively REE-depleted. In-situ analyses of maskelynite reveal little variation in anorthite content (average An% is 96.9 +/- 1.6, 2 sigma). Olivine is relatively ferroan and exhibits very little variation in forsterite content with mean Fo% of 57.7 +/- 2.0 (2 sigma). The majority of pyroxene is low-Ca pigeonite (En57Fs33Wo10). Augite (En46Fs21Wo33) is less common, comprising approximately 10% of analyzed pyroxene. Two pyroxene thermometry on co-existing orthopyroxene and augite yield an equilibrium temperature of 1070C which is in reasonable agreement with temperatures of 1096C estimated from pigeonite compositions. Rb-Sr isotopic systematics of separated fractions yield an average measured Sr-87/Sr-87 of 0.699282+/-0.000007 (2 sigma). Sr model ages are calculated using a modern day Sr-87/Sr-86 Basaltic Achondrite Best Initial (BABI) value of 0.70475, from an initial BABI value Sr-87/Sr-86 of 0.69891 and a corresponding Rb-87/Sr-97 of 0.08716. The Sr model Thermomechanical analysis (TMA) age, which represents the time of separation of a melt from a source reservoir having chondritic evolution, is 4.56+/-0.1 Ga. A Sr model T(sub RD) age, which is a Rb depletion age and assumes no contribution from Rb in the sample in the calculation, yields 4.34+/-0.1 Ga (i.e. a minimum age). The Ar-Ar dating of paired meteorite NWA 4881 reveals an age of c. 2 Ga, likely representing the last thermal event this meteorite experienced. An older Ar-40/Ar-39 age of c. 3.5 Ga may record the thermal event which produced the granulitic texture. Additional chronological constraints will be provided by Sm-Nd systematics. Ferroan Anorthosites like NWA 3163 have been interpreted to represent direct lunar magma ocean (LMO) crystallization products. If this is the case, trace element concentrations in NWA 3163 primary mineral phases should be in equilibrium with residual LMO liquids present during crystallization of those phases. Results from petrogenetic modeling suggest that the NWA 3163 protolith did not form from crystallization of an initially LREE depleted LMO but rather require an initially chondritic LMO with early garnet crystallization. Furthermore, a two-stage crystallization model where plagioclase crystalized prior to pyroxene (93% vs. 99.5% of LMO crystallization) is implied.

US/UK second level panel discussions on the health and value of: Ageing and lifetime predictions (u)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castro, Richard G

2011-01-18

Many healthy physics, engineering, and materials exchanges are being accomplished in ageing and lifetime prediction that directly supports US and UK Stockpile Management Programs. Lifetime assessment studies of silicon foams under compression - Joint AWE/LANLlLLNL study of compression set in stress cushions completed. Provides phenomenological prediction out to 50 years. Polymer volatile out-gassing studies - New exchange on the out-gassing of Ethylene Vinyl Acetate (EVA) using isotopic {sup 13}C labeling studies to interrogate mechanistic processes. Infra-red (IR) gas cell analytical capabilities developed by AWE will be used to monitor polymer out-gassing profiles. Pu Strength ageing Experiments and Constitutive Modeling -more » In recently compared modeling strategies for ageing effects on Pu yield strength at high strain rates, a US/UK consensus was reached on the general principle that the ageing effect is additive and not multiplicative. The fundamental mechanisms for age-strengthening in Pu remains unknown. Pu Surface and Interface Reactions - (1) US/UK secondment resulted in developing a metal-metal oxide model for radiation damaged studies consistent with a Modified Embedded Atom Method (MEAM) potential; and (2) Joint US/UK collaboration to study the role of impurities in hydride initiation. Detonator Ageing (wide range of activities) - (1) Long-term ageing study with field trials at Pantex incorporating materials from LANL, LLNL, SNL and AWE; (2) Characterization of PETN growth to detonation process; (3) Detonator performance modeling; and (4) Performance fault tree analysis. Benefits are a unified approach to lifetime prediction that Includes: materials characterization and the development of ageing models through improved understanding of the relationship between materials properties, ageing properties and detonator performance.« less

Use of natural diamonds to monitor 14C AMS instrument backgrounds

NASA Astrophysics Data System (ADS)

Taylor, R. E.; Southon, John

2007-06-01

To examine one component of the instrument-based background in the University of California Keck Carbon Cycle AMS spectrometer, we have obtained measurements on a set of natural diamonds pressed into sample holders. Natural diamond samples (N = 14) from different sources within rock formations with geological ages greatly in excess of 100 Ma yielded a range of currents (∼110-250 μA 12C- where filamentous graphite typically yields ∼150 μA 12C-) and apparent 14C ages (64.9 ± 0.4 ka BP [0.00031 ± 0.00002 fm] to 80.0 ± 1.1 ka BP [0.00005 ± 0.00001 fm]). Six fragments cut from a single diamond exhibited essentially identical 14C values - 69.3 ± 0.5 ka-70.6 ± 0.5 ka BP. The oldest 14C age equivalents were measured on natural diamonds which exhibited the highest current yields.

Eigenvalue computations with the QUAD4 consistent-mass matrix

NASA Technical Reports Server (NTRS)

Butler, Thomas A.

1990-01-01

The NASTRAN user has the option of using either a lumped-mass matrix or a consistent- (coupled-) mass matrix with the QUAD4 shell finite element. At the Sixteenth NASTRAN Users' Colloquium (1988), Melvyn Marcus and associates of the David Taylor Research Center summarized a study comparing the results of the QUAD4 element with results of other NASTRAN shell elements for a cylindrical-shell modal analysis. Results of this study, in which both the lumped-and consistent-mass matrix formulations were used, implied that the consistent-mass matrix yielded poor results. In an effort to further evaluate the consistent-mass matrix, a study was performed using both a cylindrical-shell geometry and a flat-plate geometry. Modal parameters were extracted for several modes for both geometries leading to some significant conclusions. First, there do not appear to be any fundamental errors associated with the consistent-mass matrix. However, its accuracy is quite different for the two different geometries studied. The consistent-mass matrix yields better results for the flat-plate geometry and the lumped-mass matrix seems to be the better choice for cylindrical-shell geometries.

Hydrothermal deformation of granular quartz sand

NASA Astrophysics Data System (ADS)

Karner, Stephen L.; Kronenberg, Andreas K.; Chester, Frederick M.; Chester, Judith S.; Hajash, Andrew

2008-05-01

Isotropic and triaxial compression experiments were performed on porous aggregates of St Peter quartz sand to explore the influence of temperature (to 225°C). During isotropic stressing, samples loaded at elevated temperature exhibit the same sigmoidal stress-strain curves and non-linear acoustic emission rates as have previously been observed from room temperature studies on sands, sandstones, and soils. However, results from our hydrothermal experiments show that the critical effective pressure (P*) associated with the onset of significant pore collapse and pervasive cataclastic flow is lower at increased temperature. Samples subjected to triaxial loading at elevated temperature show yield behavior resembling that observed from room temperature studies on granular rocks and soils. When considered in terms of distortional and mean stresses, the yield strength data for a given temperature define an elliptical envelope consistent with critical state and CAP models from soil mechanics. For the conditions we tested, triaxial yield data at low effective pressure are essentially temperature-insensitive whereas yield levels at high effective pressure are lowered as a function of elevated temperature. We interpret our yield data in a manner consistent with Arrhenius behavior expected for thermally assisted subcritical crack growth. Taken together, our results indicate that increased stresses and temperatures associated with subsurface burial will significantly alter the yield strength of deforming granular media in systematic and predictable ways.

Prediction of Precipitation Strengthening in the Commercial Mg Alloy AZ91 Using Dislocation Dynamics

DOE PAGES

Aagesen, L. K.; Miao, J.; Allison, J. E.; ...

2018-03-05

In this paper, dislocation dynamics simulations were used to predict the strengthening of a commercial magnesium alloy, AZ91, due to β-Mg 17Al 12 formed in the continuous precipitation mode. The precipitate distributions used in simulations were determined based on experimental characterization of the sizes, shapes, and number densities of the precipitates for 10-hour aging and 50-hour aging. For dislocations gliding on the basal plane, which is expected to be the dominant contributor to plastic deformation at room temperature, the critical resolved shear stress to bypass the precipitate distribution was 3.5 MPa for the 10-hour aged sample and 16.0 MPa formore » the 50-hour aged sample. The simulation results were compared to an analytical model of strengthening in this alloy, and the analytical model was found to predict critical resolved shear stresses that were approximately 30 pct lower. A model for the total yield strength was developed and compared with experiment for the 50-hour aged sample. Finally, the predicted yield strength, which included the precipitate strengthening contribution from the DD simulations, was 132.0 MPa, in good agreement with the measured yield strength of 141 MPa.« less

Prediction of Precipitation Strengthening in the Commercial Mg Alloy AZ91 Using Dislocation Dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aagesen, L. K.; Miao, J.; Allison, J. E.

In this paper, dislocation dynamics simulations were used to predict the strengthening of a commercial magnesium alloy, AZ91, due to β-Mg 17Al 12 formed in the continuous precipitation mode. The precipitate distributions used in simulations were determined based on experimental characterization of the sizes, shapes, and number densities of the precipitates for 10-hour aging and 50-hour aging. For dislocations gliding on the basal plane, which is expected to be the dominant contributor to plastic deformation at room temperature, the critical resolved shear stress to bypass the precipitate distribution was 3.5 MPa for the 10-hour aged sample and 16.0 MPa formore » the 50-hour aged sample. The simulation results were compared to an analytical model of strengthening in this alloy, and the analytical model was found to predict critical resolved shear stresses that were approximately 30 pct lower. A model for the total yield strength was developed and compared with experiment for the 50-hour aged sample. Finally, the predicted yield strength, which included the precipitate strengthening contribution from the DD simulations, was 132.0 MPa, in good agreement with the measured yield strength of 141 MPa.« less

Prediction of Precipitation Strengthening in the Commercial Mg Alloy AZ91 Using Dislocation Dynamics

NASA Astrophysics Data System (ADS)

Aagesen, L. K.; Miao, J.; Allison, J. E.; Aubry, S.; Arsenlis, A.

2018-03-01

Dislocation dynamics simulations were used to predict the strengthening of a commercial magnesium alloy, AZ91, due to β-Mg17Al12 formed in the continuous precipitation mode. The precipitate distributions used in simulations were determined based on experimental characterization of the sizes, shapes, and number densities of the precipitates for 10-hour aging and 50-hour aging. For dislocations gliding on the basal plane, which is expected to be the dominant contributor to plastic deformation at room temperature, the critical resolved shear stress to bypass the precipitate distribution was 3.5 MPa for the 10-hour aged sample and 16.0 MPa for the 50-hour aged sample. The simulation results were compared to an analytical model of strengthening in this alloy, and the analytical model was found to predict critical resolved shear stresses that were approximately 30 pct lower. A model for the total yield strength was developed and compared with experiment for the 50-hour aged sample. The predicted yield strength, which included the precipitate strengthening contribution from the DD simulations, was 132.0 MPa, in good agreement with the measured yield strength of 141 MPa.

Apollo 12 breccia 12013: Impact-induced partial Pb loss in zircon and its implications for lunar geochronology

NASA Astrophysics Data System (ADS)

Thiessen, F.; Nemchin, A. A.; Snape, J. F.; Bellucci, J. J.; Whitehouse, M. J.

2018-06-01

Apollo 12 breccia 12013 is composed of two portions, one grey in colour, the other black. The grey portion of the breccia consists mainly of felsite thought to have formed during a single crystallisation event, while the black part is characterized by presence of lithic fragments of noritic rocks and individual plagioclase crystals. In this study, U-Pb analyses of Ca-phosphate and zircon grains were conducted in both portions of the breccia. The zircon grains within the grey portion yielded a large range of ages (4154 ± 7 to 4308 ± 6 Ma, 2σ) and show decreasing U and Th concentrations within the younger grains. Moreover, some grains exhibit recrystallisation features and potentially formation of neoblasts. The latter process requires high temperatures above 1600-1700 °C leading to the decomposition of the primary zircon grain and subsequent formation of new zircon occurring as neoblasts. As a result of the high temperatures, the U-Pb system of the remaining original zircon grains was most likely open for Pb diffusion causing partial resetting and the observed range of 207Pb/206Pb ages. The event that led to the Pb loss in zircon could potentially be dated by the U-Pb system in Ca-phosphates, which have a weighted average 207Pb/206Pb age across both lithologies of 3924 ± 3 Ma (95% conf.). This age is identical within error to the combined average 207Pb/206Pb age of 3926 ± 2 Ma that was previously obtained from Ca-phosphates within Apollo 14 breccias, zircon grains in Apollo 12 impact melt breccias, and the lunar meteorite SaU 169. This age was interpreted to date the Imbrium impact. The zircon grains located within the black portion of the breccia yielded a similar range of ages (4123 ± 13 to 4328 ± 14 Ma, 2σ) to those in the grey portion. Given the brecciated nature of this part of the sample, the interpretation of these ages as representing igneous crystallisation or resetting by impact events remains ambiguous since there is no direct link to their source rocks via textural relationships or crystal chemistry. Similarly, the currently available zircon data set for all lunar samples may be distorted by partial Pb loss, resulting in meaningless and misleading age distribution patterns. Therefore, it is crucial to fully understand and recognize the processes and conditions that may lead to partial resetting of the U-Pb system in zircon in order to better constrain the magmatic and impact history of the Moon.

Intrusive rocks of the Holden and Lucerne quadrangles, Washington; the relation of depth zones, composition, textures, and emplacement of plutons

USGS Publications Warehouse

Cater, Fred W.

1982-01-01

The core of the northern Cascade Range in Washington consists of Precambrian and upper Paleozoic metamorphic rocks cut by numerous plutons, ranging in age from early Triassic to Miocene. The older plutons have been eroded to catazonal depths, whereas subvolcanic rocks are exposed in the youngest plutons. The Holden and Lucerne quadrangles span a -sizeable and representative part of this core. The oldest of the formations mapped in these quadrangles is the Swakane Biotite Gneiss, which was shown on the quadrangle maps as Cretaceous and older in age. The Swakane has yielded a middle Paleozoic metamorphic age, and also contains evidence of zircon inherited from some parent material more than 1,650 m.y. old. In this report, the Swakane is assigned an early Paleozoic or older age. It consists mostly of biotite gneiss, but interlayered with it are scattered layers and lenses of hornblende schist and gneiss, clinozoisite-epidote gneiss, and quartzite. Thickness of the Swakane is many thousands of meters, and the base is not exposed. The biotite gneiss is probably derived from a pile of siliceous volcanic rocks containing scattered sedimentary beds and basalt flows. Overlying the Swakane is a thick sequence of eugeosynclinal upper Paleozoic rocks metamorphosed to amphibolite grade. The sequence includes quartzite and thin layers of marble, hornblende schist and gneiss, graphitic schist, and smaller amounts of schist and gneiss of widely varying compositions. The layers have been tightly and complexly folded, and, in places, probably had been thrust over the overlying Swakane prior to metamorphism. Youngest of the supracrustal rocks in the area are shale, arkosic sandstone, and conglomerate of the Paleocene Swauk Formation. These rocks are preserved in the Chiwaukum graben, a major structural element of the region. Of uncertain age, but possibly as old as any of the intrusive rocks in the area, are small masses of ultramafic rocks, now almost completely altered to serpentine. These occur either as included irregular masses in later intrusives or as tectonically emplaced lenses in metamorphic rocks. Also of uncertain age but probably much younger, perhaps as young as Eocene, are larger masses of hornblendite and hornblende periodotite that grade into hornblende gabbro. These are exposed on the surface and in the underground workings of the Holden mine. Oldest of the granitoid intrusives are the narrow, nearly concordant Dumbell Mountain plutons, having a radiometric age of about 220 m.y. They consist of gneissic hornblende-quartz diorite and quartz diorite gneiss. Most contacts consist of lit-par-lit zones, but some are gradational or more rarely sharp. The plutons are typically catazonal. Closely resembling the Dumbell Mountain plutons in outcrop appearance, but differing considerably in composition, are the Bearcat Ridge plutons. These consist of gneissic quartz diorite and granodiorite. The Bearcat Ridge plutons are not in contact with older dated plutons, but because their textural and structural characteristics so closely resemble those of the Dumbell Mountain plutons, they are considered to be the same age. Their composition, however, is suggestive of a much younger age. Cutting the Dumbell Mountain plutons is the Leroy Creek pluton, consisting of gneissic biotite-quartz diorite and trondjhemite. The gneissic foliation in the Leroy Creek is characterized by a strong and pervasive swirling. Cutting both the Dumbell Mountain and Leroy Creek plutons are the almost dikelike Seven-fingered Jack plutons. These range in composition from gabbro to quartz diorite; associated with them are contact complexes of highly varied rocks characterized by gabbro and coarse-grained hornblendite. Most of the rocks are gneissic, but some are massive and structureless. Radiometric ages by various methods range from 100 to 193 m.y. Dikes, sills, small stocks, and irregular clots of leucocratic quartz diorite and granodiorite are abundant in t

Composition and ethanol production potential of cotton gin residues.

PubMed

Agblevor, Foster A; Batz, Sandra; Trumbo, Jessica

2003-01-01

Cotton gin residue (CGR) collected from five cotton gins was fractionated and characterized for summative composition. The major fractions of the CGR varied widely between cotton gins and consisted of clean lint (5-12%),hulls (16-48%), seeds (6-24%), motes (16-24%), and leaves (14-30%). The summative composition varied within and between cotton gins and consisted of ash (7.9-14.6%), acid-insoluble material (18-26%), xylan (4-15%),and cellulose (20-38%). Overlimed steam-exploded cotton gin waste was readily fermented to ethanol by Escherichia coli KO11. Ethanol yields were feedstock and severity dependent and ranged from 58 to 92.5% of the theoretical yields. The highest ethanol yield was 191 L (50 gal)/t, and the lowest was 120 L (32 gal)/t.

New geochronological evidence for the timing of early Tertiary ridge subduction in southern Alaska: A section in Geologic studies in Alaska by the U.S. Geological Survey, 1998

USGS Publications Warehouse

Bradley, Dwight C.; Parrish, Randall; Clendenen, William; Lux, Daniel R.; Layer, Paul W.; Heizler, Matthew; Donley, D. Thomas

2000-01-01

We present new U/Pb (monazite, zircon) and 40Ar/39Ar (biotite, amphibole) ages for 10 Tertiary plutons and dikes that intrude the Chugach–Prince William accretionary complex of southern Alaska. The Sanak pluton of Sanak Island yielded ages of 61.1±0.5 Ma (zircon) and 62.7±0.35 (biotite). The Shumagin pluton of Big Koniuji Island yielded a U/Pb zircon age of 61.1±0.3 Ma. Two biotite ages from the Kodiak batholith of Kodiak Island are nearly identical at 58.3±0.2 and 57.3±2.5 Ma. Amphibole from a dike at Malina Bay, Afognak Island, is 59.3±2.2 Ma; amphibole from a dike in Seldovia Bay, Kenai Peninsula, is 57.0±0.2 Ma. The Nuka pluton, Kenai Peninsula, yielded ages of 56.0±0.5 Ma (monazite) and 54.2±0.1 (biotite). Biotite plateau ages are reported for the Aialik (52.2±0.9 Ma), Tustumena (53.2±1.1 Ma), Chernof (54.2±1.1 Ma), and Hive Island (53.4±0.4 Ma) plutons of the Kenai Peninsula. Together, these new results confirm, but refine, the previously documented along-strike diachronous age trend of near-trench magmatism during the early Tertiary. We suggest that this event began at 61 Ma at Sanak Island, 2-4 m.y. later than previously supposed. An intermediate dike near Tutka Bay, Kenai Peninsula, yielded a hornblende age of 115±2 Ma. This represents a near-trench magmatic event that had heretofore gone unrecognized on the Kenai Peninsula; correlative Early Cretaceous near-trench plutons are known from the western Chugach Mountains near Palmer.

Short- and long-term effects of forage supplementation of calves during the preweaning period on performance, reproduction, and milk yield at first lactation.

PubMed

Castells, Ll; Bach, A; Terré, M

2015-07-01

Sixty female Holstein calves [body weight (BW)=39.5±3.76kg] were fed a ground starter concentrate [19% crude protein, 19% neutral detergent fiber (NDF)] during the preweaning period. Furthermore, oats hay (68% NDF) was supplemented only during the postweaning period (CON) or during both pre- and postweaning periods (OH) to evaluate performance until first breeding, diet digestibility after weaning, reproductive performance, and milk yield at first lactation. Calves were individually housed and bedded with wood shavings. All calves were offered 6 L/d of milk replacer (MR) at 12% dry matter (DM) in 2 feedings until 28d of age, 3 L/d of MR at 12% DM in 2 feedings from 29 to 44d of age calves, and 1.5 L of MR at 12% DM in 1 feeding from 45 to 51d of age. Animals were weaned at 52d of age. Starter concentrate and forage intake were recorded daily and BW weekly until 65d of age. Two weeks after weaning, total-tract apparent digestibility was determined in 6 calves per treatment. Heifer BW was recorded at 10 mo of age. Breeding and milk yield at first lactation were also recorded. Starter concentrate intake was greater in OH compared with CON animals during the preweaning period. As a result, calves in the OH treatment had greater average daily gain (ADG) than CON animals during the preweaning period. After weaning, OH calves consumed more forage than CON animals, but we found no differences between treatments in ADG and starter concentrate intake. Similarly, total-tract apparent digestibility did not differ between treatments, and BW and ADG from 2wk after weaning to 10mo of age did not differ between treatments. Moreover, no differences in reproductive performance [age at first artificial insemination (AI), age at fertile insemination, conception rate at first AI, and number of AI] or milk yield at first lactation were observed between treatments, although a positive relationship between growth rate early in life and future energy-corrected milk yield was found. We conclude that offering forage to young calves early in life allows improvements in growth before weaning and could help in the transition to mixed diets, but the improvement in growth achieved early in life was not maintained at 10mo of age. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Retail yields and palatability evaluations of individual muscles from wet-aged and dry-aged beef ribeyes and top sirloin butts that were merchandised innovatively.

PubMed

Smith, A M; Harris, K B; Griffin, D B; Miller, R K; Kerth, C R; Savell, J W

2014-05-01

Paired ribeyes (n=24) and top sirloin butts (n=24) were dry-aged or wet-aged for 35 days before being merchandised as individual muscles: M. spinalis thoracis, M. longissimus thoracis, M. gluteobiceps, and M. gluteus medius. Wet-aged subprimals had greater saleable yields than dry-aged. Dry-aged M. spinalis thoracis and M. gluteobiceps received lower consumer overall like and flavor ratings than did wet-aged; interior muscles - M. longissimus thoracis and M. gluteus medius - did not differ. Trained panelists found higher musty and putrid flavors for dry-aged muscles closer to exterior surface. These flavors may have contributed to lower consumer overall like and flavor ratings for dry-aged M. spinalis thoracis and M. gluteobiceps. Using innovative styles to cut beef allows for greater merchandising options. However, development of undesirable flavor characteristics may be more pronounced when exterior muscles - M. spinalis thoracis and M. gluteobiceps - are exposed during dry-aging to extreme conditions and are consumed individually. Copyright © 2013 Elsevier Ltd. All rights reserved.

Branching fractions for {chi}{sub cJ{yields}}pp{pi}{sup 0}, pp{eta}, and pp{omega}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Onyisi, P. U. E.; Rosner, J. L.; Alexander, J. P.

2010-07-01

Using a sample of 25.9x10{sup 6} {psi}(2S) decays acquired with the CLEO-c detector at the CESR e{sup +}e{sup -} collider, we report branching fractions for the decays {chi}{sub cJ{yields}}pp{pi}{sup 0}, pp{eta}, and pp{omega}, with J=0, 1, 2. Our results for B({chi}{sub cJ{yields}}pp{pi}{sup 0}) and B({chi}{sub cJ{yields}}pp{eta}) are consistent with, but more precise than, previous measurements. Furthermore, we include the first measurement of B({chi}{sub cJ{yields}}pp{omega}).

Cooling, exhumation, and deformation in the Hindu Kush, NW Pakistan: New constraints from preliminary 40Ar/39Ar and fission track analyses

NASA Astrophysics Data System (ADS)

Faisal, Shah; Larson, Kyle P.; Camacho, Alfredo; Coutand, Isabelle

2018-06-01

Asian crust in the Hindu Kush region in northern Pakistan records a protracted history of rifting, subduction and collision not commonly preserved within the Himalaya. Because of this, it is key to understanding the development of the southern Eurasian margin both prior to and after collision with India. New mica 40Ar/39Ar and apatite fission track geochronologic data from this region provide constraints on the kinematics of the Hindu Kush. 40Ar/39Ar muscovite and biotite ages from the late Cambrian Kafiristan pluton are 379.7 ± 1.7 Ma and 47.2 ± 0.3 Ma, respectively. The muscovite age may record cooling or partial resetting, while the biotite age is interpreted to record a thermal disruption associated with the early stages of continental collision in the Himalayan system. A 111.0 ± 0.6 Ma muscovite age from the northern part of the Tirich Mir pluton (∼123 Ma old; U-Pb) is interpreted to indicate a recrystallization event ∼12 Myrs after its intrusion. In addition, a younger muscovite age of 47.5 ± 0.2 Ma was derived from the opposite side of the same pluton in the immediate hanging wall of the Tirich Mir fault. This Eocene age is interpreted to represent the time of recrystallization during fault (re)activation in the early stages of India-Asia continent-continent collision. 40Ar/39Ar biotite analysis from the Buni-Zom pluton yields an age of 61.6 ± 1.1 Ma and is interpreted to reflect cooling at mid-upper crustal levels subsequent to the pluton's emplacement in the middle Cretaceous. Finally, 17.1-21.3 Ma 40Ar/39Ar ages from the Garam Chasma pluton and surrounding metapelites indicate cooling immediately following crystallization of the leucogranite body in the earliest Miocene/latest Oligocene. The younger cooling history is resolved by fission track dating of apatite (AFT). In the vicinity of the bounding Tirich Mir fault, the Tirich Mir pluton yields an AFT age of 1.4 ± 0.3 Ma, which is consistent with active exhumation associated with the surface uplift of the 7700+ m Tirich Mir peak. The Garam Chasma pluton has a young age of 3.5 ± 0.2 Ma, which also records rapid rock uplift and exhumation in the area. Finally, an AFT age of 9.1 ± 2.1 Ma was extracted from a metapelite in the footwall of an east verging thrust fault separating it from the Garam Chasma pluton to the west. The difference in ages, Pliocene vs. late Miocene, reflect differential cooling/exhumation paths across that structure.

The Selective Mutism Questionnaire: Measurement Structure and Validity

PubMed Central

Letamendi, Andrea M.; Chavira, Denise A.; Hitchcock, Carla A.; Roesch, Scott C.; Shipon-Blum, Elisa; Stein, Murray B.; Roesch, Scott C.

2010-01-01

Objective To evaluate the factor structure, reliability, and validity of the 17-item Selective Mutism Questionnaire. Method Diagnostic interviews were administered via telephone to 102 parents of children identified with selective mutism (SM) and 43 parents of children without SM from varying U.S. geographic regions. Children were between the ages of 3 and 11 inclusive and comprised 58% girls and 42% boys. SM diagnoses were determined using the Anxiety Disorders Interview Schedule for Children - Parent Version (ADIS-C/P); SM severity was assessed using the 17-item Selective Mutism Questionnaire (SMQ); and behavioral and affective symptoms were assessed using the Child Behavior Checklist (CBCL). An exploratory factor analysis (EFA) was conducted to investigate the dimensionality of the SMQ and a modified parallel analysis procedure was used to confirm EFA results. Internal consistency, construct validity, and incremental validity were also examined. Results The EFA yielded a 13-item solution consisting of three factors: a) Social Situations Outside of School, b) School Situations, and c) Home and Family Situations. Internal consistency of SMQ factors and total scale ranged from moderate to high. Convergent and incremental validity were also well supported. Conclusions Measure structure findings are consistent with the 3-factor solution found in a previous psychometric evaluation of the SMQ. Results also suggest that the SMQ provides useful and unique information in the prediction of SM phenomenon beyond other child anxiety measures. PMID:18698268

Effect of ageing temperatures on pseudoelasticity of Ni-rich NiTi shape memory alloy

NASA Astrophysics Data System (ADS)

Mohamad, Hishamiakim; Mahmud, Abdus Samad; Nashrudin, Muhammad Naqib; Razali, Muhammad Fauzinizam

2018-05-01

The shape memory behavior of NiTi alloy is very sensitive to alloy composition and heat treatments, particularly annealing and ageing. This paper analysed the effect of ageing towards the thermomechanical behaviour of Ti-51at%Ni wire. The analysis focused on the effect of ageing at the different temperature on thermal transformation sequence and tensile deformation behaviour with respect to the recoverability of the alloy. It was found that B2-R transformation peak appeared in the differential scanning calorimetry (DSC) measurement when the alloys were aged at the temperature between 400°C to 475°C for 30 minutes. Further ageing at 500°C to 550°C yielded two stage transformation, B2-R-B19' in cooling. All aged wires exhibited good pseudoelastic behaviour when deformed at room temperature and yielded below 1% residual strain upon unloading. Ageing at 450°C resulted the smallest unrecovered strain of about 0.4%.

Geology and ground-water resources of the Lake Dakota Plain area, South Dakota

USGS Publications Warehouse

Hopkins, William B.; Petri, Lester R.

1963-01-01

Unconsolidated deposits of Quaternary age mantle the Cretaceous rocks. Although they consist mostly of material that is too fine grained to yield water freely to wells, the Quaternary deposits contain bodies of moderately to highly permeable material that yield water copiously. Such bodies may be located only by exploratory drilling or, possibly, geophysical methods. The water differs widely in amount of mineralization and in chemical composition; the specific conductance of water from 322 wells ranged from 246 to 13,300 micromhos per centimeter. In most of the report area the water is of unsuitable quality for irrigation and domestic use. The principal source of recharge to the Quaternary deposits is infiltrating precipitation. Evapotranspiration accounts for nearly all the water discharged; the amount of water discharging into stream channels and withdrawn from wells is almost negligible by comparison. Irrigation of the area would increase the rate of recharge to the Quaternary deposits and would cause the water table to rise. Probably it would also cause an increase in the concentration of dissolved minerals in much of the ground water. Artificial drainage would be necessary to prevent waterlogging of cropland.

Fine-needle aspiration cytology of malignant hemangiopericytomas with ultrastructural and flow cytometric analyses.

PubMed

Geisinger, K R; Silverman, J F; Cappellari, J O; Dabbs, D J

1990-07-01

A hemangiopericytoma (HPC) is an uncommon soft-tissue neoplasm that may arise in many body sites. The cytologic features of fine-needle aspirates (FNAs) of HPCs have only rarely been described in the literature. We examined FNAs of malignant HPCs from the head and neck region (three) and the retroperitoneum (one) in four adults (aged 38 to 83 years). All four FNAs yielded cellular specimens that consisted of uninuclear tumor cells with high nuclear-cytoplasmic ratios. The cytomorphological spectrum included nuclei that were oval to elongate and had very finely granular, evenly distributed chromatin with one or two small but distinct nucleoli. Hemangiopericytomas yield aspirates that may be considered malignant and may suggest sarcoma. Histologically, all four neoplasms manifested high mitotic activity. The ultrastructural features of all four tumors were supportive of the diagnosis of HPC. Although a specific primary diagnosis of HPC on FNA of a soft-tissue mass is unlikely, cytologic analysis may allow diagnosis of recurrent or metastatic HPC. We were able to perform flow cytometric determinations of tumor DNA content on three of the resected neoplasms. In two, an aneuploid pattern was found, including the neoplasm with the most marked pleomorphism in the FNA. The third was diploid.

Ground-water resources of Olmsted Air Force Base, Middletown, Pennsylvania

USGS Publications Warehouse

Meisler, Harold; Longwill, Stanley Miller

1961-01-01

Olmsted Air Force Base is underlain by the Gettysburg shale of Triassic age. The Gettysburg shale at the Air Force Base consists of interbedded red sandstone, siltstone, and shale. The average strike of the strata is N. 43° E., and the strata dip to the northwest at an average angle of 26°. The transmissibility of known aquifers in the warehouse area of the Air Force Base is low. Therefore, wells in the warehouse area have low specific capacities and yield only small supplies of water. Wells on the main base, however, yield relatively large supplies of water because the transmissibilities of the aquifers are relatively high. Pumping tests in the warehouse area and the eastern area of the main base indicated the presence of impermeable boundaries in both areas. Pumping tests in the central and western parts of the main base revealed that the Susquehanna River probably is acting as a source of recharge (forms a recharge boundary) for wells in those areas. Data obtained during this investigation indicate that additional supplies of ground water for Olmsted Air Force Base could best be obtained from the western part of the main base.

Cigarettes, lung cancer, and coronary heart disease: the effects of inhalation and tar yield.

PubMed

Higenbottam, T; Shipley, M J; Rose, G

1982-06-01

Ten-year mortality rates for lung cancer and coronary heart disease have been related to cigarette smoking habits in 17 475 male civil servants aged 40-64 and in sample of 8089 male British residents aged 35-69. Both diseases were more frequent in smokers. Lung cancer rates were higher overall for "non-inhalers", particularly in heavy smokers. Tar yield correlated with the risk of lung cancer in non-inhalers but less so in inhalers. Conversely, coronary deaths were more common among inhalers, and the effect of tar/nicotine yield (such as it was) was confined to inhalers. It appears that there are subtle interactions between the amount smoked, the tar/nicotine yield of the cigarette, and the style of smoking. Thus the effects of a change in cigarette characteristics are hard to predict, and they may be different for respiratory and cardiovascular disease.

Variation in age composition among colony sizes in Cliff Swallows.

PubMed

Brown, Charles R; Roche, Erin A; Brown, Mary Bomberger

2014-09-01

Variation in group size is characteristic of most social species. The extent to which individuals sort among group sizes based on age may yield insight into why groups vary in size and the age-specific costs and benefits of different social environments. We investigated the age composition of Cliff Swallow ( Petrochelidon pyrrhonota ) colonies of different sizes over 18 years at a long-term study site in western Nebraska, USA. Using years elapsed since banding as a relative measure of age for over 194,000 birds, we found that the proportion of age-class-1 swallows (birds banded as nestlings or juveniles or adults in the year of banding) of both sexes increased in larger colonies and at colony sites becoming active later in the summer. Age composition was unrelated to how often a particular colony site was used. The effect of colony size most likely reflected the fact that older birds return to the same colony site in successive years even when the colony size there decreases, and that yearlings and immigrants benefit more from larger colonies than do older, more experienced individuals. The date effect probably resulted in part from later spring arrival by younger and/or immigrant swallows. At fumigated sites where ectoparasitic swallow bugs ( Oeciacus vicarius ) had been removed, age composition did not vary with either colony size or colony initiation date. The patterns reported here appear to be driven partially by the presence of ectoparasites and suggest that the hematophagous bugs influence variation in Cliff Swallow group composition. Our results are consistent with the hypothesis that variation in colony size reflects, in part, age-based sorting of individuals among groups.

Fracture Risk and Risk Factors for Osteoporosis.

PubMed

Schürer, Christian; Wallaschofski, Henri; Nauck, Matthias; Völzke, Henry; Schober, Hans-Christof; Hannemann, Anke

2015-05-25

As the population ages, diseases of the elderly are becoming more common, including osteoporosis. Ways to assess the risk of fracture and the distribution and effects of known risk factors for osteoporosis will be important in planning for future healthcare needs, as well as in the development of preventive strategies. The study population included 6029 men and women aged 20-90 who underwent examination in the second follow-up wave of the Study of Health in Pomerania (SHIP-2) or in the basal SHIP-Trend Study. The risk of fracture was estimated on the basis of quantitative ultrasonography of the calcaneus. Prior fractures and risk factors for osteoporosis were ascertained in standardized interviews. 4.6% of the male subjects and 10.6% of the female subjects were judged to have an elevated risk of fracture. The corresponding percentages among subjects over age 65 were 8.8% for men and 28.2% for women. Even among subjects under age 55, risk factors for osteoporosis were associated with lower bone stiffness: the mean stiffness index was 103/98 (men/women) without risk factors, 99/96 with one risk factor, and 93/95 with more than one risk factor. Logistic regression analysis yielded an odds ratio of 1.89 (95% confidence interval: 1.44-2.50; p<0.01) for prevalent fractures among subjects aged 75 and older compared to subjects under age 55. The data indicate a high prevalence of osteoporosis from age 65 onward. These findings are consistent with those of other studies from Germany and across Europe. Younger men and women should already begin taking steps to counteract modifiable risk factors.

The Las Matras tonalitic trondhjemitic pluton, central Argentina: Grenvillian-age constraints, geochemical characteristics, and regional implications

NASA Astrophysics Data System (ADS)

Sato, A. M.; Tickyj, H.; Llambías, E. J.; Sato, K.

2000-12-01

The N-S trending belt with Grenvillian-age rocks developed in central western Argentina represents the basement of an allochthonous terrane derived from Laurentia during the Early Paleozoic. The Las Matras pluton (36°46‧S, 67°07‧W) is located at the southern extension of this belt in the Las Matras Block. It consists of a low-Al tonalitic to trondhjemitic facies characteristic of an arc magmatism. Isotopic studies yielded Grenvillian Rb-Sr (1212±47 Ma) and Sm-Nd (1188±47 Ma) ages which, due to the undeformed and non-metamorphosed character of the pluton, are interpreted to represent a crystallization age of around 1200 Ma. Although this age is slightly older than available dates from other exposures of the same belt, and the undeformed feature is also distinctive for Las Matras, the depleted Sr and Nd isotopic signatures of the pluton agree with those from other magmatic rocks involved in that belt. The differences found between Las Matras and the northern exposures indicate that this belt with Grenvillian-age rocks comprises regions of non-homogeneous evolution. Although the correlation of the Lower Paleozoic platform carbonates from the sedimentary cover of the Grenvillian-age basement rocks suggests the surroundings of the Southern Grenville Province (Texas and northern Mexico) as the probable detachment site for the Argentine belt, comparison of magmatic and tectonic processes involved in these basement rocks does not indicate similar evolutions. This fact can suggest an independent evolution of the Argentine belt prior to amalgamation to the Laurentian Grenville orogen.

Excitation-emission spectra and fluorescence quantum yields for fresh and aged biogenic secondary organic aerosols

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Hyun Ji; Laskin, Alexander; Laskin, Julia

2013-05-10

Certain biogenic secondary organic aerosols (SOA) become absorbent and fluorescent when exposed to reduced nitrogen compounds such as ammonia, amines and their salts. Fluorescent SOA may potentially be mistaken for biological particles by detection methods relying on fluorescence. This work quantifies the spectral distribution and effective quantum yields of fluorescence of SOA generated from two monoterpenes, limonene and a-pinene, and two different oxidants, ozone (O3) and hydroxyl radical (OH). The SOA was generated in a smog chamber, collected on substrates, and aged by exposure to ~100 ppb ammonia vapor in air saturated with water vapor. Absorption and excitation-emission matrix (EEM)more » spectra of aqueous extracts of aged and control SOA samples were measured, and the effective absorption coefficients and fluorescence quantum yields (~0.005 for 349 nm excitation) were determined from the data. The strongest fluorescence for the limonene-derived SOA was observed for excitation = 420+- 50 nm and emission = 475 +- 38 nm. The window of the strongest fluorescence shifted to excitation = 320 +- 25 nm and emission = 425 +- 38 nm for the a-pinene-derived SOA. Both regions overlap with the excitation-emission matrix (EEM) spectra of some of the fluorophores found in primary biological aerosols. Our study suggests that, despite the low quantum yield, the aged SOA particles should have sufficient fluorescence intensities to interfere with the fluorescence detection of common bioaerosols.« less

Excitation-emission spectra and fluorescence quantum yields for fresh and aged biogenic secondary organic aerosols.

PubMed

Lee, Hyun Ji Julie; Laskin, Alexander; Laskin, Julia; Nizkorodov, Sergey A

2013-06-04

Certain biogenic secondary organic aerosols (SOA) become absorbent and fluorescent when exposed to reduced nitrogen compounds such as ammonia, amines, and their salts. Fluorescent SOA may potentially be mistaken for biological particles by detection methods relying on fluorescence. This work quantifies the spectral distribution and effective quantum yields of fluorescence of water-soluble SOA generated from two monoterpenes, limonene and α-pinene, and two different oxidants, ozone (O3) and hydroxyl radical (OH). The SOA was generated in a smog chamber, collected on substrates, and aged by exposure to ∼100 ppb ammonia in air saturated with water vapor. Absorption and excitation-emission matrix (EEM) spectra of aqueous extracts of aged and control SOA samples were measured, and the effective absorption coefficients and fluorescence quantum yields (∼0.005 for 349 nm excitation) were determined from the data. The strongest fluorescence for the limonene-derived SOA was observed for λexcitation = 420 ± 50 nm and λemission = 475 ± 38 nm. The window of the strongest fluorescence shifted to λexcitation = 320 ± 25 nm and λemission = 425 ± 38 nm for the α-pinene-derived SOA. Both regions overlap with the EEM spectra of some of the fluorophores found in primary biological aerosols. Despite the low quantum yield, the aged SOA particles may have sufficient fluorescence intensities to interfere with the fluorescence detection of common bioaerosols.

Growth and Yield Responses of Cowpea to Inoculation and Phosphorus Fertilization in Different Environments

PubMed Central

Kyei-Boahen, Stephen; Savala, Canon E. N.; Chikoye, David; Abaidoo, Robert

2017-01-01

Cowpea (Vigna unguiculata) is a major source of dietary protein and essential component of the cropping systems in semi-arid regions of Sub-Saharan Africa. However, yields are very low due to lack of improved cultivars, poor management practices, and limited inputs use. The objectives of this study were to assess the effects of rhizobia inoculant and P on nodulation, N accumulation and yield of two cowpea cultivars in Mozambique. Field study was conducted in three contrasting environments during the 2013/2014 and 2014/2015 seasons using randomized complete block design with four replications and four treatments. Treatments consisted of seed inoculation, application of 40 kg P2O5 ha-1, inoculation + P, and a non-inoculated control. The most probable number (MPN) technique was used to estimate the indigenous bradyrhizobia populations at the experimental sites. The rhizobia numbers at the sites varied from 5.27 × 102 to 1.07 × 103 cells g-1 soil. Inoculation increased nodule number by 34–76% and doubled nodule dry weight (78 to 160 mg plant-1). P application improved nodulation and interacted positively with the inoculant. Inoculation, P, and inoculant + P increased shoot dry weight, and shoot and grain N content across locations but increases in number of pods plant-1, seeds pod-1, and 100-seed weight were not consistent among treatments across locations. Shoot N content was consistently high for the inoculated plants and also for the inoculated + P fertilized plants, whereas the non-inoculated control plants had the lowest tissue N content. P uptake in shoot ranged from 1.72 to 3.77 g kg-1 and was higher for plants that received P fertilizer alone. Inoculation and P either alone or in combination consistently increased cowpea grain yield across locations with yields ranging from 1097 kg ha-1 for the non-inoculated control to 1674 kg ha-1 for the inoculant + P treatment. Grain protein concentration followed a similar trend as grain yield and ranged from 223 to 252 g kg-1 but a negative correlation between grain yield and protein concentration was observed. Inoculation increased net returns by $104–163 ha-1 over that for the control. The results demonstrate the potential of improving cowpea grain yield, quality and profitability using inoculant, although the cost-benefit for using P at the current fertilizer price is not attractive except when applied together with inoculant at low P site. PMID:28515729

Isoquinoline alkaloids supplementation on performance and carcass traits of feedlot bulls.

PubMed

Michels, Alex; Neumann, Mikael; Leão, Guilherme Fernando Mattos; Reck, Angela Maria; Bertagnon, Heloisa Godoi; Lopes, Leandro Sâmia; Souza, André Martins; Santos, Leslei Caroline Dos; Stadler Júnior, Edelmir Silvio

2018-03-02

Isoquinoline Alkaloids, derived from one plant (Macleaya cordata) can be an alternative when it is desired to increase performance in feedlot cattle. However, results on these nutritional additives in high energy diets in ruminants are still incipient in literature. In this context, the objective of this study was to evaluate performance and carcass traits of feedlot bulls supplemented with sanguinarine, the main alkaloid presents in Macleaya cordata in high energy density diets. Thirty-two crossbred Angus-Nelore bulls with mean initial body weight of 365 ± 10 kg and mean initial age of 11 ± 3 months were used. The experiment lasted 119 days, with 14 days of adaptation and 105 experimental days. Experimental diet consisted of 85% whole corn grains and 15% protein-vitamin-mineral nucleus, and supplied ad libitum. Treatments consisted of a control diet (CON) and a diet with sanguinarine supplementation (SAN) at a dosage of 4g of product sufficient to provide 6 mg of sanguinarine/ day. Experimental design was completely randomized. Dry matter intake, average daily gain and feed conversion were similar (p> 0.05) between treatments. However, SAN group animals had higher carcass yield (p = 0.045) and were more efficient in the transformation of dry matter consumed in carcass gain (p = 0.046) than CON. In addition, haptoglobin, increased throughout feedlot duration meaning high challenge for the animals due to the diet, but this behavior was similar (p> 0.05) between treatments. Sanguinarine produced positive results in relation to carcass yield, and could be used as an additive for bulls fed diets receiving high energy density diet.

Occupational chronic obstructive pulmonary disease: a systematic literature review.

PubMed

Omland, Oyvind; Würtz, Else Toft; Aasen, Tor Brøvig; Blanc, Paul; Brisman, Jonas Brisman; Miller, Martin Reginald; Pedersen, Ole Find; Schlünssen, Vivi; Sigsgaard, Torben; Ulrik, Charlotte Suppli; Viskum, Sven

2014-01-01

Occupational-attributable chronic obstructive pulmonary disease (COPD) presents a substantial health challenge. Focusing on spirometric criteria for airflow obstruction, this review of occupational COPD includes both population-wide and industry-specific exposures. We used PubMed and Embase to identify relevant original epidemiological peer-reviewed articles, supplemented with citations identified from references in key review articles. This yielded 4528 citations. Articles were excluded for lack of lung function measurement, insufficient occupational exposure classification, lack of either external or internal referents, non-accounting of age or smoking effect, or major analytic inadequacies preventing interpretation of findings. A structured data extraction sheet was used for the remaining 147 articles. Final inclusion was based on a positive qualitative Scottish Intercollegiate Guidelines Network (SIGN) score (≥2+) for study quality, yielding 25 population-wide and 34 industry/occupation-specific studies, 15 on inorganic and 19 on organic dust exposure, respectively. There was a consistent and predominantly significant association between occupational exposures and COPD in 22 of 25 population-based studies, 12 of 15 studies with an inorganic/mineral dust exposure, and 17 of 19 studies on organic exposure, even though the studies varied in design, populations, and the use of measures of exposure and outcome. A nearly uniform pattern of a dose-response relationship between various exposures and COPD was found, adding to the evidence that occupational exposures from vapors, gas, dust, and fumes are risk factors for COPD. There is strong and consistent evidence to support a causal association between multiple categories of occupational exposure and COPD, both within and across industry groups.

Identifying Early Childhood Personality Dimensions Using the California Child Q-Set and Prospective Associations With Behavioral and Psychosocial Development.

PubMed

Wilson, Sylia; Schalet, Benjamin D; Hicks, Brian M; Zucker, Robert A

2013-08-01

The present study used an empirical, "bottom-up" approach to delineate the structure of the California Child Q-Set (CCQ), a comprehensive set of personality descriptors, in a sample of 373 preschool-aged children. This approach yielded two broad trait dimensions, Adaptive Socialization (emotional stability, compliance, intelligence) and Anxious Inhibition (emotional/behavioral introversion). Results demonstrate the value of using empirical derivation to investigate the structure of personality in young children, speak to the importance of early-evident personality traits for adaptive development, and are consistent with a growing body of evidence indicating that personality structure in young children is similar, but not identical to, that in adults, suggesting a model of broad personality dimensions in childhood that evolve into narrower traits in adulthood.

French Validation of the Multidimensional Attitude Scale Toward Persons with Disabilities (MAS): The Case of Attitudes Toward Autism and Their Moderating Factors.

PubMed

Dachez, Julie; Ndobo, Andre; Ameline, Anaïs

2015-08-01

This research investigates the renewed interest in autism, the stigmatization of persons with autism and the need to better measure such stigmatization. Two studies were thus conducted on 101 and 104 participants in order to validate the French version of the Multidimensional Attitude Scale toward persons with disabilities, and examine the moderating effects of age, gender and contact on such attitudes. Both the exploratory and confirmatory factor analyses yielded a four-dimensional scale, indicating that the observed data fit with the theoretical model and that the sub-scale show an acceptable internal consistency. Results on moderating effect were less clear cut. The discussion deals with the measurement of attitudes toward people with autism as well as the role of social contact.

Effect of crude protein concentration and dietary electrolyte balance on litter quality, foot pad dermatitis, growth performance and processing yields in two medium heavy turkey hybrids.

PubMed

Veldkamp, T; Hocking, P M; Vinco, L J

2017-10-01

1. An experiment was conducted to investigate the effect of crude protein (CP) concentration and dietary electrolyte balance (DEB) on growth performance, processing yields, litter quality and foot pad dermatitis (FPD) in male turkeys from two commercial hybrids. Soya bean meal was replaced by vegetable protein sources selected for lower K concentrations to lower DEB in order to improve litter quality and subsequent quality of foot pads. 2. Effects of CP on litter friability and wetness were not consistent during the production period. FPD in turkeys fed on diets with low CP was significantly lower than FPD in turkeys fed on diets with high CP until 84 d. Growth performance was adversely affected at low CP. Processing yields were not affected by CP. 3. Litter was significantly dryer in pens of turkeys fed on diets with low DEB than in pens of turkeys fed on diets with high DEB. FPD in turkeys fed on diets with low DEB was significantly lower than in turkeys fed on diets with high DEB. Growth performance and processing yields were adversely affected at low DEB. 4. FPD in turkey hybrid A was higher than in turkey hybrid B at 28 d of age. Thereafter, no differences in FPD between turkey hybrids were observed. Growth performance and processing yields were not affected by turkey hybrid. 5. Overall, a significant interaction effect of CP × DEB was observed for FCR: in turkeys fed on the high DEB treatment, FCR of turkeys fed on the high CP diets was lower than FCR of turkeys fed on the low CP (LCP) diets whereas on the low DEB treatment, FCR was not affected by CP treatment. 6. It was concluded that litter quality can be improved and FPD may be decreased in turkeys fed on diets containing lower CP and DEB levels.

Phase feeding in a big-bird production scenario: effect on growth performance, yield, and fillet dimension.

PubMed

Brewer, V B; Owens, C M; Emmert, J L

2012-05-01

Phase feeding (PF) has been effective at maintaining broiler growth while reducing production cost, but the effect on different broiler strains and sex has not been assessed. An experiment was conducted using 4 commercial broiler strains grown up to 63 d of age (n = 1,440), comparing a PF approach to an industry-type diet. At d 17, birds began either the industry or PF regimen. The industry regimen consisted of average industry nutrient levels with periods from 17 to 32 d, 32 to 40 d, 40 to 49 d, and 49 d to the end of trial. For PF, diets were prepared that contained Lys, sulfur amino acids, and Thr levels matching the predicted requirements for birds at the beginning (high nutrient density) and end (low nutrient density) of PF. Pelleted high and low nutrient density diets were blended to produce rations containing amino acid levels that matched the predicted PF requirements over 2-d intervals. Weight gain, feed intake, and feed efficiency were calculated through d 58. Birds were commercially processed at 59, 61, or 63 d; yield and fillet dimensions were measured. Phase feeding did not effect weight gain or feed intake of broilers during the overall growth period (17-58 d). For most strains, PF did not effect final BW, yield, or fillet dimensions. However, strain and sex had greater effects on growth performance, yields, and fillet dimensions. Strains B and D had greater breast yield than strains A and C. Reduced feed costs ($0.01 to $0.04 per kilogram of gain, depending on strain) were observed for all strains with PF for the overall growth period (17-58 d). Therefore, potential savings on feed costs are possible for all strains used in this study with the incorporation of the PF regimen.

Secondary organic aerosol formation from ambient air in an oxidation flow reactor in central Amazonia

DOE PAGES

Palm, Brett B.; de Sá, Suzane S.; Day, Douglas A.; ...

2018-01-17

Secondary organic aerosol (SOA) formation from ambient air was studied using an oxidation flow reactor (OFR) coupled to an aerosol mass spectrometer (AMS) during both the wet and dry seasons at the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) field campaign. Measurements were made at two sites downwind of the city of Manaus, Brazil. Ambient air was oxidized in the OFR using variable concentrations of either OH or O 3, over ranges from hours to days (O 3) or weeks (OH) of equivalent atmospheric aging. The amount of SOA formed in the OFR ranged from 0 to asmore » much as 10 μg m -3, depending on the amount of SOA precursor gases in ambient air. Typically, more SOA was formed during nighttime than daytime, and more from OH than from O 3 oxidation. SOA yields of individual organic precursors under OFR conditions were measured by standard addition into ambient air, and confirmed to be consistent with published environmental chamber-derived SOA yields. Positive matrix factorization of organic aerosol (OA) after OH oxidation showed formation of typical oxidized OA factors and a loss of primary OA factors as OH aging increased. After OH oxidation in the OFR, the hygroscopicity of the OA increased with increasing elemental O : C up to O : C ~ 1.0, and then decreased as O : C increased further. Some possible reasons for this decrease are discussed. The measured SOA formation was compared to the amount predicted from the concentrations of measured ambient SOA precursors and their SOA yields. And while measured ambient precursors were sufficient to explain the amount of SOA formed from O 3, they could only explain 10–50 % of the SOA formed from OH. This is consistent with previous OFR studies which showed that typically unmeasured semivolatile and intermediate volatility gases (that tend to lack C = C bonds) are present in ambient air and can explain such additional SOA formation. To investigate the sources of the unmeasured SOA-forming gases during this campaign, multilinear regression analysis was performed between measured SOA formation and the concentration of gas-phase tracers representing different precursor sources. The majority of SOA-forming gases present during both seasons were of biogenic origin. Urban sources also contributed substantially in both seasons, while biomass burning sources were more important during the dry season. Our study enables a better understanding of SOA formation in environments with diverse emission sources.« less

Secondary organic aerosol formation from ambient air in an oxidation flow reactor in central Amazonia

NASA Astrophysics Data System (ADS)

Palm, Brett B.; de Sá, Suzane S.; Day, Douglas A.; Campuzano-Jost, Pedro; Hu, Weiwei; Seco, Roger; Sjostedt, Steven J.; Park, Jeong-Hoo; Guenther, Alex B.; Kim, Saewung; Brito, Joel; Wurm, Florian; Artaxo, Paulo; Thalman, Ryan; Wang, Jian; Yee, Lindsay D.; Wernis, Rebecca; Isaacman-VanWertz, Gabriel; Goldstein, Allen H.; Liu, Yingjun; Springston, Stephen R.; Souza, Rodrigo; Newburn, Matt K.; Lizabeth Alexander, M.; Martin, Scot T.; Jimenez, Jose L.

2018-01-01

Secondary organic aerosol (SOA) formation from ambient air was studied using an oxidation flow reactor (OFR) coupled to an aerosol mass spectrometer (AMS) during both the wet and dry seasons at the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) field campaign. Measurements were made at two sites downwind of the city of Manaus, Brazil. Ambient air was oxidized in the OFR using variable concentrations of either OH or O3, over ranges from hours to days (O3) or weeks (OH) of equivalent atmospheric aging. The amount of SOA formed in the OFR ranged from 0 to as much as 10 µg m-3, depending on the amount of SOA precursor gases in ambient air. Typically, more SOA was formed during nighttime than daytime, and more from OH than from O3 oxidation. SOA yields of individual organic precursors under OFR conditions were measured by standard addition into ambient air and were confirmed to be consistent with published environmental chamber-derived SOA yields. Positive matrix factorization of organic aerosol (OA) after OH oxidation showed formation of typical oxidized OA factors and a loss of primary OA factors as OH aging increased. After OH oxidation in the OFR, the hygroscopicity of the OA increased with increasing elemental O : C up to O : C ˜ 1.0, and then decreased as O : C increased further. Possible reasons for this decrease are discussed. The measured SOA formation was compared to the amount predicted from the concentrations of measured ambient SOA precursors and their SOA yields. While measured ambient precursors were sufficient to explain the amount of SOA formed from O3, they could only explain 10-50 % of the SOA formed from OH. This is consistent with previous OFR studies, which showed that typically unmeasured semivolatile and intermediate volatility gases (that tend to lack C = C bonds) are present in ambient air and can explain such additional SOA formation. To investigate the sources of the unmeasured SOA-forming gases during this campaign, multilinear regression analysis was performed between measured SOA formation and the concentration of gas-phase tracers representing different precursor sources. The majority of SOA-forming gases present during both seasons were of biogenic origin. Urban sources also contributed substantially in both seasons, while biomass burning sources were more important during the dry season. This study enables a better understanding of SOA formation in environments with diverse emission sources.

Secondary organic aerosol formation from ambient air in an oxidation flow reactor in central Amazonia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palm, Brett B.; de Sá, Suzane S.; Day, Douglas A.

Secondary organic aerosol (SOA) formation from ambient air was studied using an oxidation flow reactor (OFR) coupled to an aerosol mass spectrometer (AMS) during both the wet and dry seasons at the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) field campaign. Measurements were made at two sites downwind of the city of Manaus, Brazil. Ambient air was oxidized in the OFR using variable concentrations of either OH or O 3, over ranges from hours to days (O 3) or weeks (OH) of equivalent atmospheric aging. The amount of SOA formed in the OFR ranged from 0 to asmore » much as 10 μg m -3, depending on the amount of SOA precursor gases in ambient air. Typically, more SOA was formed during nighttime than daytime, and more from OH than from O 3 oxidation. SOA yields of individual organic precursors under OFR conditions were measured by standard addition into ambient air, and confirmed to be consistent with published environmental chamber-derived SOA yields. Positive matrix factorization of organic aerosol (OA) after OH oxidation showed formation of typical oxidized OA factors and a loss of primary OA factors as OH aging increased. After OH oxidation in the OFR, the hygroscopicity of the OA increased with increasing elemental O : C up to O : C ~ 1.0, and then decreased as O : C increased further. Some possible reasons for this decrease are discussed. The measured SOA formation was compared to the amount predicted from the concentrations of measured ambient SOA precursors and their SOA yields. And while measured ambient precursors were sufficient to explain the amount of SOA formed from O 3, they could only explain 10–50 % of the SOA formed from OH. This is consistent with previous OFR studies which showed that typically unmeasured semivolatile and intermediate volatility gases (that tend to lack C = C bonds) are present in ambient air and can explain such additional SOA formation. To investigate the sources of the unmeasured SOA-forming gases during this campaign, multilinear regression analysis was performed between measured SOA formation and the concentration of gas-phase tracers representing different precursor sources. The majority of SOA-forming gases present during both seasons were of biogenic origin. Urban sources also contributed substantially in both seasons, while biomass burning sources were more important during the dry season. Our study enables a better understanding of SOA formation in environments with diverse emission sources.« less

Secondary organic aerosol formation from ambient air in an oxidation flow reactor in central Amazonia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palm, Brett B.; de Sá, Suzane S.; Day, Douglas A.

Secondary organic aerosol (SOA) formation from ambient air was studied using an oxidation flow reactor (OFR) coupled to an aerosol mass spectrometer (AMS) during both the wet and dry seasons at the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) field campaign. Measurements were made at two sites downwind of the city of Manaus, Brazil. Ambient air was oxidized in the OFR using variable concentrations of either OH or O 3, over ranges from hours to days (O 3) or weeks (OH) of equivalent atmospheric aging. The amount of SOA formed in the OFR ranged from 0 to asmore » much as 10 µg m −3, depending on the amount of SOA precursor gases in ambient air. Typically, more SOA was formed during nighttime than daytime, and more from OH than from O 3 oxidation. SOA yields of individual organic precursors under OFR conditions were measured by standard addition into ambient air and were confirmed to be consistent with published environmental chamber-derived SOA yields. Positive matrix factorization of organic aerosol (OA) after OH oxidation showed formation of typical oxidized OA factors and a loss of primary OA factors as OH aging increased. After OH oxidation in the OFR, the hygroscopicity of the OA increased with increasing elemental O : C up to O : C ∼ 1.0, and then decreased as O : C increased further. Possible reasons for this decrease are discussed. The measured SOA formation was compared to the amount predicted from the concentrations of measured ambient SOA precursors and their SOA yields. While measured ambient precursors were sufficient to explain the amount of SOA formed from O 3, they could only explain 10–50 % of the SOA formed from OH. This is consistent with previous OFR studies, which showed that typically unmeasured semivolatile and intermediate volatility gases (that tend to lack C = C bonds) are present in ambient air and can explain such additional SOA formation. To investigate the sources of the unmeasured SOA-forming gases during this campaign, multilinear regression analysis was performed between measured SOA formation and the concentration of gas-phase tracers representing different precursor sources. The majority of SOA-forming gases present during both seasons were of biogenic origin. Urban sources also contributed substantially in both seasons, while biomass burning sources were more important during the dry season. This study enables a better understanding of SOA formation in environments with diverse emission sources.« less

New findings on green sweet pepper (Capsicum annum) pectins: Rhamnogalacturonan and type I and II arabinogalactans.

PubMed

do Nascimento, Georgia Erdmann; Iacomini, Marcello; Cordeiro, Lucimara M C

2017-09-01

Polysaccharides were extracted from sweet pepper (Capsicum annum) with hot water and named ANW (9% yield). Starch was precipitated by freeze-thaw treatment, while pectic polysaccharides (8% yield) remained soluble and consisted of GalA (67.0%), Rha (1.6%), Ara (6.4%), Xyl (0.3%), Gal (6.7%) and Glc (4.4%). A highly methoxylated homogalacturonan (HG, degree of methylesterification of 85% and degree of acetylation of 5%), and type I and type II arabinogalactans (AG-I and AG-II) were observed in NMR analyses. These were fractionated with Fehling's solution to give HG (5.5% yield) and AG fractions (0.6% yield). AG-I and AG-II were further separated by ultrafiltration. AG-II (0.2% yield) consisted of Ara (17.1%), Gal (36.0%), Rha (5.6%) and GalA (12.0%), had a molecular weight of 5.3×10 4 g/mol and methylation and 1 H/ 13 C HSQC-DEPT-NMR analyses showed that it was anchored in type I rhamnogalacturonan. This is the first study that reports the presence of AG-I and AG-II in sweet pepper fruits. Copyright © 2017 Elsevier Ltd. All rights reserved.

Prenatal maternal effects on body condition score, female fertility, and milk yield of dairy cows.

PubMed

Banos, G; Brotherstone, S; Coffey, M P

2007-07-01

In this study, maternal effects were described as age of dam at first and second calving, first-lactation body condition score (BCS) of the dam during gestation, and milk yield of the dam. The impact of these effects on first-lactation daughter BCS, fertility, and test-day milk yield was assessed. The effect of milk yield of dam on daughter 305-d yield in the latter's first 3 lactations was also investigated. The proportion of total phenotypic variance in daughter traits accounted for by maternal effects was calculated. Dams calving early for the first time (18 to 23 mo of age) had daughters that produced 4.5% more first-lactation daily milk, had 7% higher BCS, and had their first service 3 d earlier than cows whose dams calved late (30 to 36 mo). However, daughters of dams that calved early had difficulties conceiving as they needed 7% more inseminations and had a 7.5% higher return rate. Cows from second calvings of relatively young (36 to 41 mo) dams produced 6% more first-lactation daily milk, had 2% higher BCS, and showed a significantly better fertility profile than cows whose dams calved at a late age (47 to 55 mo). High maternal BCS during gestation had a favorable effect on daughter BCS, nonreturn rate, and number of inseminations per conception. However, it was also associated with a small decrease in daughter daily milk yield. Changes in dam BCS during gestation did not affect daughter performance significantly. Maternal effects of milk yield of the dam, expressed as her permanent environment during lactation, adversely affected daughter 305-d milk, fat, and protein yield. However, although the effect was significant, it was practically negligible (<0.3% of the mean). Finally, overall maternal effects accounted for a significant proportion of the total phenotypic variance of calving interval (1.4 +/- 0.6%) and nonreturn rate (1.1 +/- 0.5%).

The quantitative significance of Syntrophaceae and syntrophic partnerships in methanogenic degradation of crude oil alkanes

PubMed Central

Gray, N D; Sherry, A; Grant, R J; Rowan, A K; Hubert, C R J; Callbeck, C M; Aitken, C M; Jones, D M; Adams, J J; Larter, S R; Head, I M

2011-01-01

Libraries of 16S rRNA genes cloned from methanogenic oil degrading microcosms amended with North Sea crude oil and inoculated with estuarine sediment indicated that bacteria from the genera Smithella (Deltaproteobacteria, Syntrophaceace) and Marinobacter sp. (Gammaproteobacteria) were enriched during degradation. Growth yields and doubling times (36 days for both Smithella and Marinobacter) were determined using qPCR and quantitative data on alkanes, which were the predominant hydrocarbons degraded. The growth yield of the Smithella sp. [0.020 g(cell-C)/g(alkane-C)], assuming it utilized all alkanes removed was consistent with yields of bacteria that degrade hydrocarbons and other organic compounds in methanogenic consortia. Over 450 days of incubation predominance and exponential growth of Smithella was coincident with alkane removal and exponential accumulation of methane. This growth is consistent with Smithella's occurrence in near surface anoxic hydrocarbon degrading systems and their complete oxidation of crude oil alkanes to acetate and/or hydrogen in syntrophic partnership with methanogens in such systems. The calculated growth yield of the Marinobacter sp., assuming it grew on alkanes, was [0.0005 g(cell-C)/g(alkane-C)] suggesting that it played a minor role in alkane degradation. The dominant methanogens were hydrogenotrophs (Methanocalculus spp. from the Methanomicrobiales). Enrichment of hydrogen-oxidizing methanogens relative to acetoclastic methanogens was consistent with syntrophic acetate oxidation measured in methanogenic crude oil degrading enrichment cultures. qPCR of the Methanomicrobiales indicated growth characteristics consistent with measured rates of methane production and growth in partnership with Smithella. PMID:21914097

The quantitative significance of Syntrophaceae and syntrophic partnerships in methanogenic degradation of crude oil alkanes.

PubMed

Gray, N D; Sherry, A; Grant, R J; Rowan, A K; Hubert, C R J; Callbeck, C M; Aitken, C M; Jones, D M; Adams, J J; Larter, S R; Head, I M

2011-11-01

Libraries of 16S rRNA genes cloned from methanogenic oil degrading microcosms amended with North Sea crude oil and inoculated with estuarine sediment indicated that bacteria from the genera Smithella (Deltaproteobacteria, Syntrophaceace) and Marinobacter sp. (Gammaproteobacteria) were enriched during degradation. Growth yields and doubling times (36 days for both Smithella and Marinobacter) were determined using qPCR and quantitative data on alkanes, which were the predominant hydrocarbons degraded. The growth yield of the Smithella sp. [0.020 g(cell-C)/g(alkane-C)], assuming it utilized all alkanes removed was consistent with yields of bacteria that degrade hydrocarbons and other organic compounds in methanogenic consortia. Over 450 days of incubation predominance and exponential growth of Smithella was coincident with alkane removal and exponential accumulation of methane. This growth is consistent with Smithella's occurrence in near surface anoxic hydrocarbon degrading systems and their complete oxidation of crude oil alkanes to acetate and/or hydrogen in syntrophic partnership with methanogens in such systems. The calculated growth yield of the Marinobacter sp., assuming it grew on alkanes, was [0.0005 g(cell-C)/g(alkane-C)] suggesting that it played a minor role in alkane degradation. The dominant methanogens were hydrogenotrophs (Methanocalculus spp. from the Methanomicrobiales). Enrichment of hydrogen-oxidizing methanogens relative to acetoclastic methanogens was consistent with syntrophic acetate oxidation measured in methanogenic crude oil degrading enrichment cultures. qPCR of the Methanomicrobiales indicated growth characteristics consistent with measured rates of methane production and growth in partnership with Smithella. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

Neoarchean metamorphism recorded in high-precision Sm-Nd isotope systematics of garnets from the Jack Hills (Western Australia)

NASA Astrophysics Data System (ADS)

Eccles, K. A.; Baxter, E. F.; Mojzsis, S. J.; Marschall, H.; Williams, M. L.; Jercinovic, M. J.

2013-12-01

Studies of metasedimentary rocks from the Jack Hills, which host Earth's oldest known detrital minerals, have focused on zircon and occasionally monazite or xenotime, but no attention has been directed toward one of the most common mineral markers of metamorphism: garnet. Garnet can provide a record of the post-depositional, prograde metamorphic history of Archean metasedimentary rocks. Additionally, the use of a newly developed detrital garnet dating technique [1,2] may reveal information about pre-depositional metamorphism that could address lingering questions about the nature and timing of Earth's earliest tectonometamorphic events. Here we investigate garnet from the Jack Hills metasedimentary rocks to test whether they record in situ metamorphism or are a detrital relict of even older metamorphic events. We identified garnet in two bulk quartz-pebble conglomerate samples collected from the 'discovery' outcrop at Eranondoo Hill in the Jack Hills of Western Australia. Electron microprobe analyses of polished grains and SEM measurements of unpolished grain surfaces are consistent, revealing garnet composition indicative of a single generation/population of predominantly almandine-spessartine solid solution (~10-35% mole fraction spessartine). Compositional maps of garnet grains reveal little zoning and no discontinuities, most consistent with a single growth event. Dating Jack Hills' garnet via the Sm-Nd system is possible due to continued development of small sample analysis techniques, including running NdO+ TIMS analyses with Ta2O5 activator [3] permitting <50 ppm 2 sigma analytical precision on a 400pg in-house standard and continued improvement in blanks (<15pg full procedural blanks). Additionally, employing a nondestructive chemical prescreening technique (tabletop SEM) allows for grouping of multiple grains based on chemical similarity. Final Nd loads in the 450-750pg range routinely yield dates with precisions <×10Ma for two point isochrons between clean garnet (Sm/Nd ≥ 1.0) and their leached inclusion populations [2]. Four grouped garnet grain separates from one sample yield preliminary dates of 2703.6×6.0Ma, 2612.4×6.0Ma, 2605.0×5.5Ma, and 2567.3×8.3Ma, while the second sample yielded a date of 2579.6×4.6 Ma (2σ). Compositional and geochronologic data indicate likely in situ garnet growth during a late Archean greenschist facies metamorphic event. These dates are generally consistent with published monazite ages placing a metamorphic event at ~ca.2.65Ga [4,5]. It remains possible that an as yet unidentified detrital garnet component is present and may explain some of the scatter in absolute age. [1] Baxter EF, Jordan MK & Inglis JD, 2010, Goldschmidt [2] Baxter EF, Eccles KA & Sullivan N, 2012, Goldschmidt [3] Harvey J & Baxter EF, 2009, Chem Geol, 258, 251-257 [4] Rasmussen B, et al, 2010, Precambrian Res, 180, 26-46 [5] Iizuka T, et al, 2010, Contrib Mineral Petr, 160, 803-823

EBSD Imaging of Monazite: a Petrochronological Tool?

NASA Astrophysics Data System (ADS)

Mottram, C. M.; Cottle, J. M.

2014-12-01

Recent advances in in-situ U-Th/Pb monazite petrochronology allow ages obtained from micron-scale portions of texturally-constrained, individual crystals to be placed directly into a quantitative Pressure-Temperature framework. However, there remain major unresolved challenges in linking monazite ages to specific deformation events and discerning the effects of deformation on the isotopic and elemental tracers in these phases. Few studies have quantitatively investigated monazite microstructure, and these studies have largely focused only on crystals produced experimentally (e.g. Reddy et al., 2010). The dispersion in age data commonly yielded from monazite U-Th/Pb datasets suggest that monazite dynamically recrystallises during deformation. It remains unclear how this continual recrystallisation is reflected in the monazite crystal structure, and how this subsequently impacts the ages (or age ranges) yielded from single crystals. Here, combined laser ablation split-stream analysis of deformed monazite, EBSD imaging and Pressure-Temperature (P-T) phase equilibria modelling is used to quantify the influence of deformation on monazite (re)crystallisation mechanisms and its subsequent effect on the crystallographic structure, ages and trace-element distribution in individual grains. These data provide links between ages and specific deformation events, thus helping further our understanding of the role of dynamic recrystallisation in producing age variation within and between crystals in a deformed rock. These data provide a new dimension to the field of petrochronology, demonstrating the importance of fully integrating the Pressure-Temperature-time-deformation history of accessory phases to better interpret the meaningfulness of ages yielded from deformed rocks. Reddy, S. et al., 2010. Mineralogical Magazine 74: 493-506

Quantum Yields in Mixed-Conifer Forests and Ponderosa Pine Plantations

NASA Astrophysics Data System (ADS)

Wei, L.; Marshall, J. D.; Zhang, J.

2008-12-01

Most process-based physiological models require canopy quantum yield of photosynthesis as a starting point to simulate carbon sequestration and subsequently gross primary production (GPP). The quantum yield is a measure of photosynthetic efficiency expressed in moles of CO2 assimilated per mole of photons absorbed; the process is influenced by environmental factors. In the summer 2008, we measured quantum yields on both sun and shade leaves for four conifer species at five sites within Mica Creek Experimental Watershed (MCEW) in northern Idaho and one conifer species at three sites in northern California. The MCEW forest is typical of mixed conifer stands dominated by grand fir (Abies grandis (Douglas ex D. Don) Lindl.). In northern California, the three sites with contrasting site qualities are ponderosa pine (Pinus ponderosa C. Lawson var. ponderosa) plantations that were experimentally treated with vegetation control, fertilization, and a combination of both. We found that quantum yields in MCEW ranged from ~0.045 to ~0.075 mol CO2 per mol incident photon. However, there were no significant differences between canopy positions, or among sites or tree species. In northern California, the mean value of quantum yield of three sites was 0.051 mol CO2/mol incident photon. No significant difference in quantum yield was found between canopy positions, or among treatments or sites. The results suggest that these conifer species maintain relatively consistent quantum yield in both MCEW and northern California. This consistency simplifies the use of a process-based model to accurately predict forest productivity in these areas.

National water-quality assessment of the Lake Erie-Lake St. Clair Basin, Michigan, Indiana, Ohio, Pennsylvania, and New York; environmental and hydrologic setting

USGS Publications Warehouse

Casey, G.D.; Myers, Donna N.; Finnegan, D.P.; ,

1998-01-01

The Lake Erie-Lake St. Clair Basin covers approximately 22,300 mi ?(square miles) in parts of Indiana, Michigan, Ohio, Pennsylvania, and New York. Situated in two major physiographic provinces, the Appalachian Plateaus and the Central Lowland, the basin includes varied topographic and geomorphic features that affect the hydrology. As of 1990, the basin was inhabited by approximately 10.4 million people. Lake effect has a large influence on the temperature and precipitation of the basin, especially along the leeward southeast shore of Lake Erie. Mean annual precipitation generally increases from west to east, ranging from 31.8 inches at Detroit, Mich., to 43.8 inches at Erie, Pa. The rocks that underlie the Lake Erie-Lake St. Clair Basin range in age from Cambrian through Pennsylvanian, but only Silurian through Pennsylvanian rocks are part of the shallow ground-water flow system. The position of the basin on the edge of the Michigan and Appalachian Basins is responsible for the large range in geologic time of the exposed rocks. Rock types range from shales, siltstones, and mudstones to coarse-grained sandstones and conglomerates. Carbonate rocks consisting of limestones, dolomites, and calcareous shales also underlie the basin. All the basin is overlain by Pleistocene deposits- till, fine-grained stratified sediments, and coarse-grained stratified sediments-most of Wisconsinan age. A system of buried river valleys filled with various lacustrine, alluvial, and coarse glacial deposits is present in the basin. The soils of the Lake Erie-Lake St. Clair Basin consist of two dominant soil orders: Alfisols and Inceptisols. Four other soil orders in the basin (Mollisols, Histisols, Entisols, and Spodosols) are of minor significance, making up less than 8 percent of the total area. The estimated water use for the Lake Erie-Lake St. Clair Basin for 1990 was 10,649 Mgal/d (million gallons per day). Power generation accounted for about 77 percent of total water withdrawals for the basin, whereas agriculture accounted for the least water-use withdrawals, at an estimated 38 Mgal/d. About 98 percent of the total water used in the basin was drawn from surface water; the remaining 2 percent was from ground water. Agricultural and urban land are the predominant land covers in the basin. Agriculture makes up approximately 74.7 percent of the total basin area; urban land use accounts for 11.2 percent; forested areas constitute 10.5 percent; and water, wetlands, rangeland, and barren land constitute less than 4.0 percent. The eight principal streams in the basin are the Clinton, Huron, and Raisin Rivers in Michigan, the Maumee, Sandusky, Cuyahoga, and Grand Rivers in Ohio, and Cattaraugus Creek in New York. The Maumee River, the largest stream in the basin, drains 6,609 mi? and discharges just under 24 percent of the streamflow from the basin into Lake Erie. Combined, the eight principal streams discharge approximately 54 percent of the surface water from the basin to the Lake Erie system per year. Average runoff increases from west to east in the basin. The glacial and recent deposits comprise the unconsolidated aquifers and confining units within the basin. Yields of wells completed in tills range from 0 to 20 gal/min (gallon per minute), but yields generally are near the lower part of this range. Fine-grained stratified deposits can be expected to yield from 0 to 3 gal/ min, and coarse-grained stratified deposits can yield 0.3 to 2,050 gal/min. Pennsylvanian sandstones can yield more than 25 gal/min, but they generally yield 10 to 25 gal/min. Mississippian sandstones in the basin generally yield 2 to 100 gal/min. The Mississippian and Devonian shales are considered to be confining units; in places, they produce small quantities of water from fractures at or near the bedrock surface. Wells completed in the Devonian and Silurian carbonates yield 25 to 500 gal/min, but higher yields have been reported in several zones.

Psychometrics of the Laffrey Health Conception Scale for adolescents.

PubMed

Yarcheski, Adela; Mahon, Noreen E; Yarcheski, Thomas J

2005-01-01

The purposes of this methodological study were to factor analyze the Laffrey Health Conception Scale (LHCS) and to assess construct validity of the instrument with early adolescents. The final sample consisted of 230 early adolescents, aged 12 to 14, who responded to instrument packets in classrooms in an urban middle school. Data obtained on the LHCS were subjected to principal components factor analysis with oblique rotation. A two-factor solution was accepted, which is consistent with early adolescents' conceptions of health. Factor I was labeled Wellness and Factor II was labeled Clinical Health. A higher order factor analysis yielded one factor with 26 items, labeled the LHCS for Early Adolescents. The 26-item LHCS had a coefficient alpha of .95. Construct validity was assessed by testing three theoretical propositions, which significantly linked health conception to social support, self-esteem, and positive health practices. The findings indicate that the LHCS is a reliable and valid measure of health conceptions in early adolescents. Results also offer flexibility to researchers interested in testing theory involving the constructs of the definition of health, wellness, and clinical health in early adolescents.

Long-term cognitive and behavioral consequences of neonatal encephalopathy following perinatal asphyxia: a review

PubMed Central

Swaab, Hanna; de Vries, Linda S.; Jongmans, Marian J.

2007-01-01

Neonatal encephalopathy (NE) following perinatal asphyxia (PA) is considered an important cause of later neurodevelopmental impairment in infants born at term. This review discusses long-term consequences for general cognitive functioning, educational achievement, neuropsychological functioning and behavior. In all areas reviewed, the outcome of children with mild NE is consistently positive and the outcome of children with severe NE consistently negative. However, children with moderate NE form a more heterogeneous group with respect to outcome. On average, intelligence scores are below those of children with mild NE and age-matched peers, but within the normal range. With respect to educational achievement, difficulties have been found in the domains reading, spelling and arithmetic/mathematics. So far, studies of neuropsychological functioning have yielded ambiguous results in children with moderate NE. A few studies suggest elevated rates of hyperactivity in children with moderate NE and autism in children with moderate and severe NE. Conclusion: Behavioral monitoring is required for all children with NE. In addition, systematic, detailed neuropsychological examination is needed especially for children with moderate NE. PMID:17426984

Influence of inocula and grains on sclerotia biomass and carotenoid yield of Penicillium sp. PT95 during solid-state fermentation.

PubMed

Han, Jian-Rong; Yuan, Jing-Ming

2003-10-01

Various inocula and grains were evaluated for carotenoid production by solid-state fermentation using Penicillium sp. PT95. Millet medium was more effective in both sclerotia growth and carotenoid production than other grain media. An inoculum in the form of sclerotia yielded higher sclerotia biomass compared to either a spore inoculum or a mycelial pellet inoculum. Adding wheat bran to grain medium favored the formation of sclerotia. However, neither the inoculum type nor addition of wheat bran resulted in a significant change in the carotenoid content of sclerotia. Among grain media supplemented with wheat bran (wheat bran:grain =1:4 w/w, dry basis), a medium consisting of rice and wheat bran gave the highest sclerotia biomass (15.10 g/100 g grain), a medium consisting of buckwheat and wheat bran gave the highest content of carotenoid in sclerotia (0.826 mg/g dry sclerotia), and a medium consisting of millet and wheat bran gave the highest carotenoid yield (11.457 mg/100 g grain).

Geodynamic evolution of the lithosphere of the Sea of Okhotsk region from geophysical data

NASA Astrophysics Data System (ADS)

Verzhbitsky, E. V.; Kononov, M. V.

2006-06-01

The tectonic structure and anomalous distributions of geophysical fields of the Sea of Okhotsk region are considered; the lack of reliable data on the age of the lithosphere beneath basins of various origins in the Sea of Okhotsk is noted. Model calculations based on geological and geophysical data yielded an age of 65 Ma (the Cretaceous-Paleocene boundary) for the Central Okhotsk rise underlain by the continental lithosphere. This estimate agrees with the age (the end of the Cretaceous) derived from seismostratigraphic data. A comparative analysis of theoretical and measured heat fluxes in the Akademii Nauk Rise, underlain by a thinned continental crust, is performed. The analysis points to a higher (by 20%) value of the measured thermal background of the rise, which is consistent with a high negative gradient of gravity anomalies in this area. Calculations yielded an age of 36 Ma (the Early Oligocene) and a lithosphere thickness of 50 km for the South Okhotsk depression, whose seafloor was formed by processes of backarc spreading. The estimated age of the depression is supported by kinematic data on the region; the calculated thickness of the lithosphere coincides with the value estimated from data of magnetotelluric sounding here. This indicates that the formation time (36 Ma) of the South Okhotsk depression was estimated correctly. Numerical modeling performed for the determination of the basement age of rifting basins in the Sea of Okhotsk gave the following estimates: 18 Ma (the Early Miocene) for the Deryugin basin, 12 Ma (the Middle Miocene) for the TINRO basin, and 23 Ma (the Late Oligocene) for the West Kamchatka trough. These estimates agree with the formation time (Oligocene-Quaternary) of the sedimentary cover in rifting basins of the Sea of Okhotsk derived from geological and geophysical data. Model temperature estimates are obtained for lithologic and stratigraphic boundaries of the sedimentary cover in the Deryugin and TINRO basins and the West Kamchatka trough; the temperature analysis indicates that the latter two structures are promising for oil and hydrocarbon gas generation; the West Kamchatka trough possesses better reservoir properties compared to the TINRO and Deryugin basins. The latter is promising for the generation of hydrocarbon gas. Paleogeodynamic reconstructions of the Sea of Okhotsk region evolution are obtained for times of 90, 66, and 36 Ma on the basis of kinematic, geomagnetic, structural, tectonic, geothermal, and other geological and geophysical data.

The southwestern extension of the Jiao-Liao-Ji belt in the North China Craton: Geochronological and geochemical evidence from the Wuhe Group in the Bengbu area

NASA Astrophysics Data System (ADS)

Liu, Chaohui; Zhao, Guochun; Liu, Fulai; Cai, Jia

2018-04-01

The Wuhe complex is located at the southeastern margin of the North China Craton. The complex consists of metamorphosed Paleoproterozoic potassic granitoids and supracrustal rocks, of which the latter include the Fengyang and Wuhe groups. Meta-mafic rocks from the lower Wuhe Group have igneous zircon U-Pb ages of 2126 ± 37 Ma with εHf(t) values of -6.22 to +8.38, and xenocrystic zircons of 2.39-2.36 Ga, 2.55-2.54 Ga and 2.77-2.69 Ga. Geochemically, the meta-mafic rocks can be classified into two groups. Group 1 island arc tholeiites display flat to slightly right declined REE patterns and moderately negative Nb, Ta, Zr, and Ti anomalies. Group 2 mature arc calcalkaline basalts display strongly fractionated chondrite-normalized REE patterns and evidently negative Nb, Ta and Ti anomalies. These meta-mafic rocks formed by partial melting of sub-arc depleted mantle wedge which had been modified by slab-derived melts at an active continental margin. Depositional age of the group can be constrained in the period of 2.16-2.10 Ga based on ages of the youngest detrital zircons and latter intrusions. U-Pb ages of detrital zircons yield major age peaks of 2.69 Ga and 2.52 Ga, with minor peaks at 2.88 Ga, 2.78 Ga, 2.35 Ga and 2.17 Ga, most of which are derived from the late Mesoarchean to early Paleoproterozoic granitoids in the Wuhe complex and the Jiaodong Terrane. Metamorphic zircons in the marbles coexisting with garnet amphibolites or granulites occur as either single grains or overgrowth (or recrystallization) rims surrounding magmatic zircon cores and yield ages of 1882 ± 19 Ma to 1844 ± 15 Ma. The comparable ca. 2.1 Ga potassic granites with A-type granite affinity, the ca. 2.1 Ga meta-mafic rocks with arc-like geochemical features, the 2.1-1.9 Ga meta-sedimentary units and the 1.9-1.8 Ga subduction- and collision-related granulite-facies metamorphism suggest that the Wuhe complex and the Jiao-Liao-Ji Belt share the same late Paleoproterozoic tectonic evolution process and the former is the southwestern extension of the latter.

Biochemical indicators for the bioavailability of organic carbon in ground water

USGS Publications Warehouse

Chapelle, F.H.; Bradley, P.M.; Goode, D.J.; Tiedeman, C.; Lacombe, P.J.; Kaiser, K.; Benner, R.

2009-01-01

The bioavailability of total organic carbon (TOC) was examined in ground water from two hydrologically distinct aquifers using biochemical indicators widely employed in chemical oceanography. Concentrations of total hydrolyzable neutral sugars (THNS), total hydrolyzable amino acids (THAA), and carbon-normalized percentages of TOC present as THNS and THAA (referred to as "yields") were assessed as indicators of bioavailability. A shallow coastal plain aquifer in Kings Bay, Georgia, was characterized by relatively high concentrations (425 to 1492 ??M; 5.1 to 17.9 mg/L) of TOC but relatively low THNS and THAA yields (???0.2%-1.0%). These low yields are consistent with the highly biodegraded nature of TOC mobilized from relatively ancient (Pleistocene) sediments overlying the aquifer. In contrast, a shallow fractured rock aquifer in West Trenton, New Jersey, exhibited lower TOC concentrations (47 to 325 ??M; 0.6 to 3.9 mg/L) but higher THNS and THAA yields (???1% to 4%). These higher yields were consistent with the younger, and thus more bioavailable, TOC being mobilized from modern soils overlying the aquifer. Consistent with these apparent differences in TOC bioavailability, no significant correlation between TOC and dissolved inorganic carbon (DIC), a product of organic carbon mineralization, was observed at Kings Bay, whereas a strong correlation was observed at West Trenton. In contrast to TOC, THNS and THAA concentrations were observed to correlate with DIC at the Kings Bay site. These observations suggest that biochemical indicators such as THNS and THAA may provide information concerning the bioavailability of organic carbon present in ground water that is not available from TOC measurements alone.

Paleozoic magmatism and porphyry Cu-mineralization in an evolving tectonic setting in the North Qilian Orogenic Belt, NW China

NASA Astrophysics Data System (ADS)

Qiu, Kun-Feng; Deng, Jun; Taylor, Ryan D.; Song, Kai-Rui; Song, Yao-Hui; Li, Quan-Zhong; Goldfarb, Richard J.

2016-05-01

The NWW-striking North Qilian Orogenic Belt records the Paleozoic accretion-collision processes in NW China, and hosts Paleozoic Cu-Pb-Zn mineralization that was temporally and spatially related to the closure of the Paleo Qilian-Qinling Ocean. The Wangdian Cu deposit is located in the eastern part of the North Qilian Orogenic Belt, NW China. Copper mineralization is spatially associated with an altered early Paleozoic porphyritic granodiorite, which intruded tonalites and volcaniclastic rocks. Alteration zones surrounding the mineralization progress outward from a potassic to a feldspar-destructive phyllic assemblage. Mineralization consists mainly of quartz-sulfide stockworks and disseminated sulfides, with ore minerals chalcopyrite, pyrite, molybdenite, and minor galena and sphalerite. Gangue minerals include quartz, orthoclase, biotite, sericite, and K-feldspar. Zircon LA-ICPMS U-Pb dating of the ore-bearing porphyritic granodiorite yielded a mean 206Pb/238U age of 444.6 ± 7.8 Ma, with a group of inherited zircons yielding a mean U-Pb age of 485 ± 12 Ma, consistent with the emplacement age (485.3 ± 6.2 Ma) of the barren precursor tonalite. Rhenium and osmium analyses of molybdenite grains returned model ages of 442.9 ± 6.8 Ma and 443.3 ± 6.2 Ma, indicating mineralization was coeval with the emplacement of the host porphyritic granodiorite. Rhenium concentrations in molybdenite (208.9-213.2 ppm) suggest a mantle Re source. The tonalities are medium-K calc-alkaline. They are characterized by enrichment of light rare-earth elements (LREEs) and large-ion lithophile elements (LILEs), depletion of heavy rare-earth elements (HREEs) and high-field-strength elements (HFSEs), and minor negative Eu anomalies. They have εHf(t) values in the range of +3.6 to +11.1, with two-stage Hf model ages of 0.67-1.13 Ga, suggesting that the ca. 485 Ma barren tonalites were products of arc magmatism incorporating melts from the mantle wedge and the lithosphere. In contrast, the 40-m.y.-younger ore-bearing porphyritic granodiorite is sub-alkaline and peraluminous. They are enriched in LREEs and LILEs, depleted in HFSEs, and show weak negative Eu anomalies. They display εHf(t) values of captured or inherited zircons in the range of +8.5 to +10.0, and younger two-stage Hf model ages of 0.78 Ga and 0.86 Ga, similar to those of ca. 485 Ma tonalite. The ca. 445 Ma zircons have εHf(t) values of -2.1 to +9.9, with two-stage Hf model ages of 0.75-1.27 Ga. Moreover, they have relatively high oxygen fugacity than that of the precursor barren tonalite. The ca. 445 Ma magmas at Wangdian thus formed in a subduction setting, and incorporated melts from the subduction-modified lithosphere that had previously been enriched by additions of chalcophile and siderophile element-rich materials by the earlier magmatism and metasomatism during the Paleo Qilian-Qinling Ocean subduction event.

Assessment of Grating Acuity in Infants and Toddlers Using an Electronic Acuity Card: The Dobson Card.

PubMed

Mohan, Kathleen M; Miller, Joseph M; Harvey, Erin M; Gerhart, Kimberly D; Apple, Howard P; Apple, Deborah; Smith, Jordana M; Davis, Amy L; Leonard-Green, Tina; Campus, Irene; Dennis, Leslie K

2016-01-01

To determine if testing binocular visual acuity in infants and toddlers using the Acuity Card Procedure (ACP) with electronic grating stimuli yields clinically useful data. Participants were infants and toddlers ages 5 to 36.7 months referred by pediatricians due to failed automated vision screening. The ACP was used to test binocular grating acuity. Stimuli were presented on the Dobson Card. The Dobson Card consists of a handheld matte-black plexiglass frame with two flush-mounted tablet computers and is similar in size and form to commercially available printed grating acuity testing stimuli (Teller Acuity Cards II [TACII]; Stereo Optical, Inc., Chicago, IL). On each trial, one tablet displayed a square-wave grating and the other displayed a luminance-matched uniform gray patch. Stimuli were roughly equivalent to the stimuli available in the printed TACII stimuli. After acuity testing, each child received a cycloplegic eye examination. Based on cycloplegic retinoscopy, patients were categorized as having high or low refractive error per American Association for Pediatric Ophthalmology and Strabismus vision screening referral criteria. Mean acuities for high and low refractive error groups were compared using analysis of covariance, controlling for age. Mean visual acuity was significantly poorer in children with high refractive error than in those with low refractive error (P = .015). Electronic stimuli presented using the ACP can yield clinically useful measurements of grating acuity in infants and toddlers. Further research is needed to determine the optimal conditions and procedures for obtaining accurate and clinically useful automated measurements of visual acuity in infants and toddlers. Copyright 2016, SLACK Incorporated.

Galaxy properties from J-PAS narrow-band photometry

NASA Astrophysics Data System (ADS)

Mejía-Narváez, A.; Bruzual, G.; Magris, C. G.; Alcaniz, J. S.; Benítez, N.; Carneiro, S.; Cenarro, A. J.; Cristóbal-Hornillos, D.; Dupke, R.; Ederoclite, A.; Marín-Franch, A.; de Oliveira, C. Mendes; Moles, M.; Sodre, L.; Taylor, K.; Varela, J.; Ramió, H. Vázquez

2017-11-01

We study the consistency of the physical properties of galaxies retrieved from spectral energy distribution (SED) fitting as a function of spectral resolution and signal-to-noise ratio (SNR). Using a selection of physically motivated star formation histories, we set up a control sample of mock galaxy spectra representing observations of the local Universe in high-resolution spectroscopy, and in 56 narrow-band and 5 broad-band photometry. We fit the SEDs at these spectral resolutions and compute their corresponding stellar mass, the mass- and luminosity-weighted age and metallicity, and the dust extinction. We study the biases, correlations and degeneracies affecting the retrieved parameters and explore the role of the spectral resolution and the SNR in regulating these degeneracies. We find that narrow-band photometry and spectroscopy yield similar trends in the physical properties derived, the former being considerably more precise. Using a galaxy sample from the Sloan Digital Sky Survey (SDSS), we compare more realistically the results obtained from high-resolution and narrow-band SEDs (synthesized from the same SDSS spectra) following the same spectral fitting procedures. We use results from the literature as a benchmark to our spectroscopic estimates and show that the prior probability distribution functions, commonly adopted in parametric methods, may introduce biases not accounted for in a Bayesian framework. We conclude that narrow-band photometry yields the same trend in the age-metallicity relation in the literature, provided it is affected by the same biases as spectroscopy, albeit the precision achieved with the latter is generally twice as large as with the narrow-band, at SNR values typical of the different kinds of data.

Improved segmentation of cerebellar structures in children

PubMed Central

Narayanan, Priya Lakshmi; Boonazier, Natalie; Warton, Christopher; Molteno, Christopher D; Joseph, Jesuchristopher; Jacobson, Joseph L; Jacobson, Sandra W; Zöllei, Lilla; Meintjes, Ernesta M

2016-01-01

Background Consistent localization of cerebellar cortex in a standard coordinate system is important for functional studies and detection of anatomical alterations in studies of morphometry. To date, no pediatric cerebellar atlas is available. New method The probabilistic Cape Town Pediatric Cerebellar Atlas (CAPCA18) was constructed in the age-appropriate National Institute of Health Pediatric Database asymmetric template space using manual tracings of 16 cerebellar compartments in 18 healthy children (9–13 years) from Cape Town, South Africa. The individual atlases of the training subjects were also used to implement multi atlas label fusion using multi atlas majority voting (MAMV) and multi atlas generative model (MAGM) approaches. Segmentation accuracy in 14 test subjects was compared for each method to ‘gold standard’ manual tracings. Results Spatial overlap between manual tracings and CAPCA18 automated segmentation was 73% or higher for all lobules in both hemispheres, except VIIb and X. Automated segmentation using MAGM yielded the best segmentation accuracy over all lobules (mean Dice Similarity Coefficient 0.76; range 0.55–0.91). Comparison with existing methods In all lobules, spatial overlap of CAPCA18 segmentations with manual tracings was similar or higher than those obtained with SUIT (spatially unbiased infra-tentorial template), providing additional evidence of the benefits of an age appropriate atlas. MAGM segmentation accuracy was comparable to values reported recently by Park et al. (2014) in adults (across all lobules mean DSC = 0.73, range 0.40–0.89). Conclusions CAPCA18 and the associated multi atlases of the training subjects yield improved segmentation of cerebellar structures in children. PMID:26743973

Chemiluminescence as a condition monitoring method for thermal aging and lifetime prediction of an HTPB elastomer.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gillen, Kenneth Todd; Minier, Leanna M. G.; Celina, Mathias C.

Chemiluminescence (CL) has been applied as a condition monitoring technique to assess aging related changes in a hydroxyl-terminated-polybutadiene based polyurethane elastomer. Initial thermal aging of this polymer was conducted between 110 and 50 C. Two CL methods were applied to examine the degradative changes that had occurred in these aged samples: isothermal 'wear-out' experiments under oxygen yielding initial CL intensity and 'wear-out' time data, and temperature ramp experiments under inert conditions as a measure of previously accumulated hydroperoxides or other reactive species. The sensitivities of these CL features to prior aging exposure of the polymer were evaluated on the basismore » of qualifying this method as a quick screening technique for quantification of degradation levels. Both the techniques yielded data representing the aging trends in this material via correlation with mechanical property changes. Initial CL rates from the isothermal experiments are the most sensitive and suitable approach for documenting material changes during the early part of thermal aging.« less

The effects of interstitial content and annealing on the flow and fracture behavior on polycrystalline beta-NiAl

NASA Technical Reports Server (NTRS)

Weaver, M. L.; Levit, V.; Kaufman, M. J.; Noebe, R. D.

1994-01-01

The strain behavior of three polycrystalline NiAl alloys has been investigated at temperatures between 300 and 1200 K. Yield stress plateaus, yield stress transients upon a ten-fold increase in strain rate, work hardening peaks, and dips in the strain rate sensitivity (SRS) have been observed between 700 and 800 K. These observations are indicative of dynamic strain aging (DSA) and are discussed in terms of conventional strain aging theories.

Growth and yield in natural stands of slash pine and suggested management alternatives

Treesearch

Frank A. Bennett

1980-01-01

Yields are presented by stand age, site index, and stand basal area at the beginning of a growth period. Differences between these yields and those projected 20 and 50 years ago are explained partly by changing definitions of normal or full stocking and partly by changes in forest management. If only pulpwood harvesting is envisioned, fairly high stocking is needed to...

Hardness - Yield Strength Relation of Al-Mg-Si Alloys

NASA Astrophysics Data System (ADS)

Praveen Sekhar, Aluru; Nandy, Supriya; Ray, Kalyan Kumar; Das, Debdulal

2018-03-01

Assessing the mechanical properties of materials through indentation hardness test is an attractive method, rather than obtaining the properties through destructive approach like tensile testing. The present work emphasizes on the relation between hardness and yield strength of Al-Mg-Si alloys considering Tabor type equations. Al-0.5Mg-0.4Si alloy has been artificially aged at various temperatures (100 to 250 °C) for different time durations (0.083 to 1000 h) and the ageing response has been assessed by measuring the Vickers hardness and yield strength. Correlations of the existing data from the open literature have also been reviewed. Lastly, it has been explained that the deviation in obtained relation from Tabor’s equation is owing to the dislocation accumulation during indentation.

Relationship between Yield Point Phenomena and the Nanoindentation Pop-in Behavior of Steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahn, T.-H.; Oh, C.-S.; Lee, K.

2012-01-01

Pop-ins on nanoindentation load-displacement curves of a ferritic steel were correlated with yield drops on its tensile stress-strain curves. To investigate the relationship between these two phenomena, nanoindentation and tensile tests were performed on annealed specimens, prestrained specimens, and specimens aged for various times after prestraining. Clear nanoindentation pop-ins were observed on annealed specimens, which disappeared when specimens were indented right after the prestrain, but reappeared to varying degrees after strain aging. Yield drops in tensile tests showed similar disappearance and appearance, indicating that the two phenomena, at the nano- and macro-scale, respectively, are closely related and influenced by dislocationmore » locking by solutes (Cottrell atmospheres).« less

Lactation and calf weight traits of mature crossbred cows fed varying daily levels of metabolizable energy.

PubMed

Jenkins, T G; Ferrell, C L; Roberts, A J

2000-01-01

Our objective was to evaluate differences in lactation traits and calf weights produced by F1 cows under varying daily metabolizable energy availability. Measures of milk yields and calf weight traits were recorded on mature F1 cows. The cows were produced from matings of Angus or Hereford dams with sires representing Angus/Hereford, Shorthorn, Galloway, Longhorn, Nellore, and Salers breeds. The cows' daily DM intakes of a diet composed of a corn silage or alfalfa silage plus corn silage were recorded from approximately 2 wk postpartum until the calves were weaned at an average age of 170 d. Milk yield measurements were recorded when the calves were approximately 14, 28, 56, 84, 112, 140, and 168 d of age. Sources of variation considered for the traits of interest included sire breed of the cow (SBC) and the covariates weaning age of the calf and daily metabolizable energy intake (DMEI) of the cow for lactation and calf weights. The linear and quadratic effects were evaluated for DMEI. The SBC x DMEI (linear) interaction was significant for total milk yield. Sire breed of cow differences (P < .05) were observed for milk yield at time of peak yield, persistency, preweaning ADG, and weaning weight. Salers- and Shorthorn-sired cows had greater (P < .05) peak yield than Galloway, Longhorn, or Nellore cross-bred cows but were not significantly different from the Hereford/Angus. Increasing DMEI linearly increased peak yield and total yield (P < .05). Preweaning ADG of calves from Nellore-sired cows was greater (P < .05) than all SBC. Preweaning ADG of calves from Galloway-sired cows was less than all SBC (P < .05). The linear effect of DMEI was heterogeneous across SBC for total yield. The pooled quadratic effect of DMEI was significant for all traits except birth weight. The DMEI for expression of maximum weaning weight was estimated to be 29 Mcal. Feed efficiency ratios for the test period were 28, 27, 30, 25, 28, 32, and 30 g calf weight:Mcal DMEI for reference and 1980s Angus/Hereford-, Shorthorn-, Galloway-, Longhorn-, Nellore-, and Salers-sired cows, respectively, at the DMEI level of 29 Mcal.

Conventional U-Pb dating versus SHRIMP of the Santa Barbara Granite Massif, Rondonia, Brazil

USGS Publications Warehouse

Sparrenberger, I.; Bettencourt, Jorge S.; Tosdal, R.M.; Wooden, J.L.

2002-01-01

The Santa Ba??rbara Granite Massif is part of the Younger Granites of Rondo??nia (998 - 974 Ma) and is included in the Rondo??nia Tin Province (SW Amazonian Craton). It comprises three highly fractionated metaluminous to peraluminous within-plate A-type granite units emplaced in older medium-grade metamorphic rocks. Sn-mineralization is closely associated with the late-stage unit. U-Pb monazite conventional dating of the early-stage Serra do Cicero facies and late-stage Serra Azul facies yielded ages of 993 ?? 5 Ma and 989 ?? 13 Ma, respectively. Conventional multigrain U-Pb isotope analyses of zircon demonstrate isotopic disturbance (discordance) and the preservation of inherited older zircons of several different ages and thus yield little about the ages of Sn-granite magmatism. SHRIMP U-Pb ages for the Santa Ba??rbara facies association yielded a 207Pb/206Pb weighted-mean age of 978 ?? 13 Ma. The textural complexity of the zircon crystals of the Santa Ba??rbara facies association, the variable concentrations of U, Th and Pb, as well as the mixed inheritance of zircon populations are major obstacles to using conventional multigrain U-Pb isotopic analyses. Sm-Nd model ages and ??Nd (T) values reveal anomalous isotopic data, attesting to the complex isotopic behaviour within these highly fractionated granites. Thus, SHRIMP U-Pb zircon and conventional U-Pb monazite dating methods are the most appropriate to constrain the crystallization age of the Sn-bearing granite systems in the Rondo??nia Tin Province.

[Reproductive function of the male rat after a flight on the Kosmos-1129 biosatellite].

PubMed

Serova, L V; Denisova, L A; Apanasenko, Z I; Kuznetsova, M A; Meĭzerov, E S

1982-01-01

Male rats that were flown for 18.5 days on Cosmos-1129 were mated postflight with intact females. The mating 5 days postflight when the ejaculate consisted of spermatozoids that were exposed to zero-g effects in the mature stage yielded the litter which lagged behind the controls with respect to the growth and development during the first postnatal month. The mating 2.5-3 months postflight when the ejaculate consisted of spermatozoids that were exposed to zero-g effects at the stem cell stage yielded the litter which did not differ from the control.

Assessment of the Pb-Pb and U-Pb chronometry of the early solar system

NASA Astrophysics Data System (ADS)

Tera, Fouad; Carlson, Richard W.

1999-06-01

An evaluation of early solar system chronometry by the Pb-Pb and U-Pb methods is provided. Specifically, three consequential factors are examined: procedure of age calculation, extent of terrestrial Pb contamination, and initial Pb isotopic composition. On a Pb-Pb diagram, high temperature inclusions of the Allende meteorite are tightly organized into a well-defined line (inside a potentially dispersive mixing field), which is consistent with the inclusions containing initial Pb that is more primitive than that of Cañon Diablo troilite (PAT). Consequences of the possible existence of a pre-PAT Pb to the evolution history of the solar nebula are discussed. Phosphates from the ordinary chondrite St. Séverin appear to be contaminated by terrestrial Pb, a condition that renders age calculation based on subtraction of PAT inaccurate. The Pb-Pb mixing line of these phosphates indicates an age of 4.558 Ga. Interestingly, Angra dos Reis phosphate and pyroxene, as well as pyroxene of the other angrite Lewis Cliff 86010 fall precisely on the line defined by St. Séverin phosphates. Whole rocks of ordinary chondrites are pictorially and explicitly shown to be seriously contaminated with terrestrial Pb, thus their single-stage U-Pb ages may not be suitable markers of time. Because their true crystallization ages are often younger than the whole rocks, and because of the possibility of multistage evolution, phosphates of ordinary chondrites may yield single-stage ages older than their true crystallization ages. A hypothetical numerical demonstration is provided. On the basis of revised ages and new observations we provide an ;updated; chronometry for the early solar system.

Mechanical Properties of Elastomeric Impression Materials: An In Vitro Comparison

PubMed Central

De Angelis, Francesco; Caputi, Sergio; D'Amario, Maurizio; D'Arcangelo, Camillo

2015-01-01

Purpose. Although new elastomeric impression materials have been introduced into the market, there are still insufficient data about their mechanical features. The tensile properties of 17 hydrophilic impression materials with different consistencies were compared. Materials and Methods. 12 vinylpolysiloxane, 2 polyether, and 3 hybrid vinylpolyether silicone-based impression materials were tested. For each material, 10 dumbbell-shaped specimens were fabricated (n = 10), according to the ISO 37:2005 specifications, and loaded in tension until failure. Mean values for tensile strength, yield strength, strain at break, and strain at yield point were calculated. Data were statistically analyzed using one-way ANOVA and Tukey's tests (α = 0.05). Results. Vinylpolysiloxanes consistently showed higher tensile strength values than polyethers. Heavy-body materials showed higher tensile strength than the light bodies from the same manufacturer. Among the light bodies, the highest yield strength was achieved by the hybrid vinylpolyether silicone (2.70 MPa). Polyethers showed the lowest tensile (1.44 MPa) and yield (0.94 MPa) strengths, regardless of the viscosity. Conclusion. The choice of an impression material should be based on the specific physical behavior of the elastomer. The light-body vinylpolyether silicone showed high tensile strength, yield strength, and adequate strain at yield/brake; those features might help to reduce tearing phenomena in the thin interproximal and crevicular areas. PMID:26693227

Two-phase Neogene extension in the northwestern basin and range recorded in a single thermochronology sample

USGS Publications Warehouse

Colgan, J.P.; Shuster, D.L.; Reiners, P.W.

2008-01-01

We use a combination of apatite 4He/3He, (U-Th)/ He, and fission-track thermochronology to date slip on the Surprise Valley fault in northeastern California by analyzing a single sample from the Warner Range in the footwall of the fault. This sample, a granitic clast from a conglomerate, yielded a fission-track age of 11.6 ?? 2.8 Ma and a (U-Th)/He age of 3.02 ?? 0.52 Ma. Geologic relationships indicate that this sample was buried to a depth of ???3.3 km prior to exhumation during slip on the Surprise Valley fault. Fission-track age and length data indicate that the sample was fully reset (>120 ??C) prior to exhumation, which began sometime after 14 Ma. A single aliquot of nine apatite grains was step-heated for 4He/3He analysis; modeling of the resulting 4He distribution indicates that cooling from <80 ??C to ???20 ??C occurred between 3 and 1 Ma. Interconsistent time-temperature (t-T) solutions to the combined 4He/3He, (U-Th)/He, and fission-track data require two distinct periods of cooling, consistent with non-continuous slip on the Surprise Valley fault. Early cooling and fault slip took place between 14 and 8 Ma, followed by more recent fault slip ca. 3 Ma. This timing is consistent with both local geologic relationships and with the regional timing of faulting along the western margin of the Basin and Range Province. These data demonstrate the resolving power of combined fission-track, (U-Th)/He, and 4He/3He thermochronometric data to extract low-temperature t-T information from a single sample close to Earth's surface. ?? 2008 The Geological Society of America.

Re-Os isotopic systematics in chromitites from the Stillwater Complex, Montana, USA

NASA Astrophysics Data System (ADS)

Marcantonio, Franco; Zindler, Alan; Reisberg, Laurie; Mathez, E. A.

1993-08-01

New Re-Os isotopic data on chromitites of the Stillwater Complex demonstrate isotopic equilibrium between cumulate chromite and whole rock. Initial osmium isotopic ratios for the chromitites, chosen for their freshness, are consistent with derivation from a mantle-derived magma that suffered little or no interaction with the continental crust prior to crystallization. Molybdenite, separated from a sample of the G-chromitite, yields a Re-Os age of 2740 Ma, indistinguishable from the age of the intrusion. The presence of molybdenite documents rhenium, and probably osmium, mobilization by hydrothermal fluids that permeated the intrusion shortly after crystallization. Initial osmium isotopic variability observed in chromitites and other rocks from the Stillwater Complex could result from interaction with these fluids. In this context, there is no compelling reason to call on assimilation of crust by mantle-derived magma to explain the osmium or neodymium isotopic variability. Although osmium isotopic systematics have been affected by hydrothermal processes, Re-Os results demonstrate that more than 95 percent of the osmium, and by inference other PGEs in the Stillwater Complex, derive from the mantle.

New constraints on the geochronology and Sm-Nd isotopic characteristics of Bas-Drâa mafic dykes, Anti-Atlas of Morocco

NASA Astrophysics Data System (ADS)

El Bahat, Abdelhakim; Ikenne, Moha; Cousens, Brian; Söderlund, Ulf; Ernst, Richard; Klausen, Martin B.; Youbi, Nasrrddine

2017-03-01

The Precambrian inliers of the Anti-Atlas belt across the southern part of Morocco contain numerous mafic dyke and sill swarms, which are thought to represent the erosional remnants of Proterozoic Large Igneous Provinces (LIPs). As part of an extended research campaign to date and characterize these LIPs, two amphiboles from one dyke within the Bas-Drâa inlier (western Anti-Atlas) yielded consistent 40Ar-39Ar ages of 611 Ma ± 1.3; i.e., evidence of magmatic activity during the Ediacaran (635-542 Ma). Furthermore, Nd isotope ratios and model ages identifies four groups of dykes within the Bas-Drâa inlier, all of which were derived from a previously enriched mantle reservoir with very low 143Nd/144Nd ratios (0.51065-0.51170) and corresponding εNd(t) values (-16.44 to -2.45). Such low Nd-ratios arguably reflect either a contribution of crustal components, such as the Paleoproterozoïc schisto-granitic basement, or metasomatic modification of the sub-continental lithospheric mantle.

The protective effect of marriage for survival: a review and update.

PubMed

Rendall, Michael S; Weden, Margaret M; Favreault, Melissa M; Waldron, Hilary

2011-05-01

The theory that marriage has protective effects for survival has itself lived for more than 100 years since Durkheim's groundbreaking study of suicide (Durkheim 1951 [1897]). Investigations of differences in this protective effect by gender, by age, and in contrast to different unmarried statuses, however, have yielded inconsistent conclusions. These investigations typically either use data in which marital status and other covariates are observed in cross-sectional surveys up to 10 years before mortality exposure, or use data from panel surveys with much smaller sample sizes. Their conclusions are usually not based on formal statistical tests of contrasts between men and women or between never-married, divorced/separated, and widowed statuses. Using large-scale pooled panel survey data linked to death registrations and earnings histories for U.S. men and women aged 25 and older, and with appropriate contrast tests, we find a consistent survival advantage for married over unmarried men and women, and an additional survival "premium" for married men. We find little evidence of mortality differences between never-married, divorced/separated, and widowed statuses.

Influence of an organic acid blend and essential oil blend, individually or in combination, on growth performance, carcass parameters, apparent digestibility, intestinal microflora and intestinal morphology of broilers.

PubMed

Basmacioğlu-Malayoğlu, H; Ozdemir, P; Bağriyanik, H A

2016-04-01

This study aimed to evaluate the influence of an organic acid (OA) and essential oil (EO) blends, individually or in combination, on growth performance, carcass parameters, apparent digestibility, intestinal microflora and intestinal morphology of broilers. A total of 480 one-d-old male Ross 308 chicks were randomly assigned to 4 treatments consisting of 4 replicates each (n = 30 birds in each replicate). Dietary treatments consisted of a basal diet (control), and basal diet supplemented with 2 g/kg OA blend (OAB), 300 mg/kg EO blend (EOB), or with 2 g/kg OA and 300 mg/kg EO blend (OAB-EOB) for 42 d. The dietary supplementation with EO blend or in combination with OA blend increased body weight gain and improved feed efficiency as compared to control. Dietary treatments had no significant effects on feed consumption or relative organ weights of broilers. The OAB diet increased carcass yield compared to the control diet but the lowest carcass yield occurred with the OAB-EOB combination. Birds fed on EOB and OAB-EOB diets had lower ileum Escherichia coli counts than birds fed on the control diet. There was no significant effect of treatments on apparent digestibility at 16-21 d but the EOB and OAB-EOB diets increased apparent digestibility of dry matter and crude protein during the finisher period (d 37-42) compared to the control diet. Birds fed on the EOB and OAB-EOB diets had greater villus height in the ileum at 21 and 42 d of age and had lower crypt depth in the ileum at 42 d of age than birds given the control diet. In conclusion, beneficial effects of the use of EO blend individually or in combination with the OA blend were observed but the OA blend alone was ineffective. Furthermore, the use of the combination of OA and EO was more effective, in some respects, than their individual use.

Summary of geology and ground-water resources of Passaic County, New Jersey

USGS Publications Warehouse

Carswell, L.D.; Rooney, J.G.

1976-01-01

Ground water in Passaic County occurs in intergranular openings of unconsolidated stratified deposits of Quaternary age and in joints and fractures in consolidated rocks of Precambrian, Paleozoic, and Triassic age.The Brunswick Formation of Triassic age is the most important aquifer in the southeastern one-third of Passaic County. Reported yields of public supply and industrial wells range from 50 to 510 gallons per minute (3 to 32 litres per second) and the median yield is 130 gallons per minute (8 litres per second). Most of these wells are 200 to 400 feet (61 to 122 metres) deep. The median yield of all public supply and industrial wells over 300 feet (91 metres) deep and 8 inches (203 millimetres) or larger in diameter is 230 gallons per minute (15 litres per second). Crystalline rocks of Precambrian age are the major source of ground water for domestic use in the northwestern two-thirds of Passaic County. Reported well yields range from 1 to 200 gallons per minute (.06 to 13 litres per second). The median reported yield of domestic wells is 5 gallons per minute (.31 litres per second) and that of public supply wells is 30 gallons per minute (2 litres per second).Other consolidated rocks--rocks of Paleozoic age and the Watchung Basalt of Traissic age--are utilized primarily for domestic water supplies in Passaic County. Reported yields of wells tapping the Paleozoic rocks range from less than 1 to 35 gallons per minute (.06 to 2 litres per second) and the median yield is 10 gallons per minute (.63 litres per second). Reported yields of domestic wells tapping the Watchung Basalt range from less than 1 to 40 gallons per minute (.06 to 3 litres per second) and the median yield is 12 gallons per minute (.76 litres per second). However, reported yields of nine industrial and commercial wells range from 50 to 180 gallons per minute (3 to 11 litres per second).Unconsolidated stratified deposits of Quaternary age are locally an important source of ground water for public supply and industrial use in parts of Passaic County. These deposits have not been extensively explored but are potentially an important source of ground water for future development. Reported yields of wells tapping the stratified deposits range from 4 to 920 gallons per minute (.25 to 58 litres per second). The median reported yield of domestic wells is 16 gallons per minute (1 litre per second) and that of public supply and industrial wells is 130 gallons per minute (8 litres per second. Depths of wells depend upon the thickness of the deposits. Reported depths range from 22 to 170 feet (7 to 52 metres).The quality of ground water in Passaic County varies from one aquifer to another. Water from the Precambrian rocks is soft to moderately hard (34 to 104 milligrams per litre) and is low in dissolved solids (66 to 159 milligrams per litre). Water from the Brunswick Formation is moderately hard to very hard (89 to 540 milligrams per litre). The dissolved solids content ranges from 129 to 563 milligrams per litre). The occurrence of more highly mineralized water at depth in the Brunswick Formation is indicated by an analysis, made in 1885, of 16,000 milligrams per litre of dissolved solids at a depth of 2,050 feet (625 metres) in a well in Paterson. Water from two wells tapping the Quaternary deposits is moderately hard (65 and 83 milligrams per litre) and has dissolved solids contents of 122 and 133 milligrams per litre).Water use from both surface and ground-water supplies in Passaic County averaged about 106 million gallons per day (4.6 cubic metres per second) in 1965. Ground water probably accounts for 5 to 10 percent of this total. Ground-water pumpage by the major public supply companies in the county has increased from 2.1 million gallons per day (.09 cubic metres per second) in 1951 to 4.39 million gallons per day (.19 cubic metres per second) in 1968. About 80 percent of the 4.39 million gallons per day (.19 cubic metres per second) was from wells tapping the Brunswick Formation in the southern part of the county.

Apparent CFC and 3H/ 3He age differences in water from Floridan Aquifer springs

NASA Astrophysics Data System (ADS)

Happell, James D.; Opsahl, Stephen; Top, Zafer; Chanton, Jeffrey P.

2006-03-01

The apparent CFC-11, -12 and -113 ages of Upper Floridan Aquifer water discharged from 31 springs located in Florida and Georgia ranged from 11 to 44 years when samples were collected in 2002 and 2003. Apparent 3H/ 3He ages in these springs ranged from 12 to 66 years. Some of the springs sampled did not yield valid CFC ages because one or more of the CFCs were contaminated by non-atmospheric sources. Of the 31 springs sampled, six were contaminated with all three CFCs and nine were contaminated with one or two CFCs. Of the remaining 16 springs, the CFC distributions of four could be modeled assuming a single source of water, and 11 were best modeled by assuming two sources of water, with one of the water sources >60 years old. The CFC and 3H/ 3He apparent ages and the simple mixing models applied to these ages suggest that past impacts to the water quality of water recharging the sampled springs may take anywhere from 0 to ˜60 years or more to appear in the discharging spring water. In 27 springs where both 3H/ 3He ages and CFC ages were available, five springs gave similar results between the two techniques, while in the other 22 cases the 3H/ 3He apparent ages were 8-40 years greater than the CFC ages. Large excesses of 4He were observed in many of the springs, consistent with a source of older water. This older water may also carry an additional and unaccounted for source of 3He, which may be responsible for the greater 3H/ 3He ages relative to the CFC ages. We believe that the large excess 3He and 4He values and apparent age differences are related to regional climate variations because our samples were obtained at the end of a 4-year drought.

Effect of aging on lignin content, composition and enzymatic saccharification in Corymbia hybrids and parental taxa between years 9 and 12

DOE PAGES

Healey, Adam L.; Lupoi, Jason S.; Lee, David J.; ...

2016-07-02

Corymbia (a eucalypt) is an important forestry genus and a potential lignocellulosic bioenergy feedstock. The composition of the lignocellulosic cell wall significantly impacts pretreatment efficiency and conversion to biofuel but is variable and changes with age. In this study, we estimated Klason lignin content, composition, and monosaccharide (glucose and xylose) release after enzymatic saccharification of untreated and hydrothermally pretreated biomass from Corymbia parental species Corymbia torelliana (CT), Corymbia citriodora subsp. variegata (spotted gum; CCV), and interspecific F1 hybrids (CT x CCV) at ages 9 and 12 years from planting. Analysis of lignin composition derived from syringyl/guaiacyl monolignols (S/G) found significantmore » differences among taxa, with CT S/G ratios (2.2 and 2.0) being significantly lower than CCV (2.6 and 2.3) or hybrids (2.5 and 2.3) at ages 9 and 12 respectively. In general, enzymatic saccharification yields from untreated biomass were significantly different among taxa, with CT (113 and 75 mg g -1) and hybrids (108 and 81 mg g -1) yielding significantly higher glucose from untreated biomass than CCV (82 and 56 mg g -1) at ages 9 and 12 respectively. Comparison of traits within taxa between ages 9 and 12 found S/G ratios and glucose yields from untreated biomass were significantly lower in CT, CCV and hybrid taxa. As a result, the formation of lignocellulosic cell walls is complex, influenced by genetics and age of material, requiring optimization of rotation age for biofuel production and other industrial processes.« less

Effect of aging on lignin content, composition and enzymatic saccharification in Corymbia hybrids and parental taxa between years 9 and 12

DOE Office of Scientific and Technical Information (OSTI.GOV)

Healey, Adam L.; Lupoi, Jason S.; Lee, David J.

Corymbia (a eucalypt) is an important forestry genus and a potential lignocellulosic bioenergy feedstock. The composition of the lignocellulosic cell wall significantly impacts pretreatment efficiency and conversion to biofuel but is variable and changes with age. In this study, we estimated Klason lignin content, composition, and monosaccharide (glucose and xylose) release after enzymatic saccharification of untreated and hydrothermally pretreated biomass from Corymbia parental species Corymbia torelliana (CT), Corymbia citriodora subsp. variegata (spotted gum; CCV), and interspecific F1 hybrids (CT x CCV) at ages 9 and 12 years from planting. Analysis of lignin composition derived from syringyl/guaiacyl monolignols (S/G) found significantmore » differences among taxa, with CT S/G ratios (2.2 and 2.0) being significantly lower than CCV (2.6 and 2.3) or hybrids (2.5 and 2.3) at ages 9 and 12 respectively. In general, enzymatic saccharification yields from untreated biomass were significantly different among taxa, with CT (113 and 75 mg g -1) and hybrids (108 and 81 mg g -1) yielding significantly higher glucose from untreated biomass than CCV (82 and 56 mg g -1) at ages 9 and 12 respectively. Comparison of traits within taxa between ages 9 and 12 found S/G ratios and glucose yields from untreated biomass were significantly lower in CT, CCV and hybrid taxa. As a result, the formation of lignocellulosic cell walls is complex, influenced by genetics and age of material, requiring optimization of rotation age for biofuel production and other industrial processes.« less

Dynamic strain aging and plastic instabilities

NASA Astrophysics Data System (ADS)

Mesarovic, Sinisa Dj.

1995-05-01

A constitutive model proposed by McCormick [(1988) Theory of flow localization due to dynamic strain ageing. Acta. Metall.36, 3061-3067] based on dislocation-solute interaction and describing dynamic strain aging behavior, is analyzed for the simple loading case of uniaxial tension. The model is rate dependent and includes a time-varying state variable, representing the local concentration of the impurity atoms at dislocations. Stability of the system and its post-instability behavior are considered. The methods used include analytical and numerical stability and bifurcation analysis with a numerical continuation technique. Yield point behavior and serrated yielding are found to result for well defined intervals of temperature and strain rate. Serrated yielding emerges as a branch of periodic solutions of the relaxation oscillation type, similar to frictional stick-slip. The distinction between the temporal and spatial (loss of homogeneity of strain) instability is emphasized. It is found that a critical machine stiffness exists above which a purely temporal instability cannot occur. The results are compared to the available experimental data.

Geology and ground-water resources of southeastern New Hampshire

USGS Publications Warehouse

Bradley, Edward

1964-01-01

The continued growth and development of southeastern New Hampshire, an area of about 390 square miles adjacent to the Atlantic Ocean, will depend partly on effectively satisfying the demand for water, which has increased rapidly since World War II. The report identifies and describes the principal geologic units with respect to the occurrence of ground water. These units include bedrock and the various unconsolidated deposits that mantle the bedrock surface discontinuously throughout the area. The bedrock formations, consisting of igneous and metamorphic rocks, chiefly of Paleozoic age, form a single water-bearing unit. Ground water is in joints and fractures. The fractures are small and scattered and therefore impart only a low permeability to the rocks. Wells in the bedrock commonly produce small but reliable supplies of ground water at depths of less than 150 feet. The yields of about 80 wells inventoried for this report ranged from 1? to 100 gpm (gallons per minute) and the median was 912 gpm. Depths ranged from 45 to 600 feet. The unconsolidated deposits consist of glacial drift of Pleistocene age; swamp deposits, alluvium, and beach deposits of Recent age; and eolian deposits of Pleistocene -and Recent age. For this report the glacial drift is divided into till, ice-contact deposits, marine deposits, and outwash and shore deposits. Glacial till forms a discontinuous blanket, commonly less than 15 but in some hills (drumlins) as much as about 200 feet thick. It has a low permeability but, because of its widespread outcrop area, it has been utilized as a source of water for numerous domestic supplies. Because most wells in till are shallow, many fail to meet modern demands during dry summers. Ice-contact deposits locally form kames, kame terraces, kame plains, and ice-channel fillings throughout the area. They overlie bedrock and till and range in thickness from less than 1 foot to as much as 190 feet. In general, the ice-contact deposits are coarse textured and permeable, but variations in- the physical and hydrologic properties of a single deposit and from deposit to deposit are common. Ice-contact deposits are the source of the larger ground-water supplies in southeastern New Hampshire. Marine deposits underlie lowlands and valleys to a distance of about 20 miles inland from the present coastline. They commonly overlie bedrock and till and at places overlie or are interbedded with ice-contact deposits. Marine deposits range in thickness from less than 1 foot to possibly 75 feet. They are fine textured and impermeable; they do not yield water to wells in southeastern New Hampshire but generally act as a barrier to ground-water movement. Outwash and shore deposits form broad sand plains or gently sloping terraces of small extent. At most places the outwash and shore deposits, which range in thickness from less than 1 foot to about 50 feet, overlie marine deposits, but at some places they overlie bedrock, till, or ice-contact deposits. The outwash and shore deposits are fine textured and moderately permeable. They commonly yield enough ground water to meet the needs of farms, homes, and small industries. Alluvium underlies the flood plains and channels of the principal streams and overlies bedrock and older unconsolidated deposits wherever streams cross the older units. The alluvium generally is not tapped by wells. Beach deposits occupy areas along the Atlantic Ocean between promontories of bedrock or till. In general beach deposits are permeable and are a source of water supplies for domestic use. Yields of wells are limited, however, by the danger of drawing in salty water. Recharge in southeastern New Hampshire is derived principally from precipitation on outcrop areas of ice-contact deposits and outwash and shore deposits during the nongrowing season. Ground water is discharged naturally by springs, by effluent seepage to streams and other bodies of surface water, and by evapotranspiration. It

Leucine and valine supplementation of low-protein diets for broiler chickens from 21 to 42 days of age.

PubMed

Ospina-Rojas, I C; Murakami, A E; Duarte, C R A; Nascimento, G R; Garcia, E R M; Sakamoto, M I; Nunes, R V

2017-04-01

The objective of this study was to determine the requirements and interactions between the standardized ileal digestible (SID) Leu and Val levels in low-protein diets, and their effects on performance, serum characteristics, carcass yield and diameter of muscle fibers of broiler chickens from d 21 to 42 posthatch. A total of 1,500 21-day-old Cobb 500 male broiler chickens were distributed in a completely randomized design in a 5 × 5 factorial arrangement for a total of 25 treatments with 3 replicates of 20 birds each. Treatments consisted of 5 SID Leu levels (1.0, 1.2, 1.4, 1.6, or 1.8%) and 5 SID Val levels (0.52, 0.67, 0.82, 0.97, or 1.12%). At 42 d of age, there was interaction (P < 0.05) between the SID levels of Leu and Val on feed intake and weight gain. There was a quadratic effect (P < 0.05) of Leu and Val levels on feed conversion, with minimal point estimated at the levels of 1.19 and 0.86%, respectively. Dietary Leu supplementation reduced linearly (P < 0.05) serum concentrations of triglycerides and β-hydroxybutyrate. Dietary Leu increased (P ≤ 0.05) the fiber diameters of the pectoralis major muscle and breast yield at the levels of 1.24 and 1.13%, respectively, while the thigh yield was improved with the level of 0.71% Val. Abdominal fat decreased linearly (P < 0.05) with increasing levels of dietary Leu and Val. The SID Leu and Val levels needed to optimize weight gain and feed conversion in low-CP diets for broiler chickens from d 21 to 42 posthatch were estimated at 1.15 and 0.86%, and 1.19 and 0.86%, respectively. The supplementation of Leu and Val can reduce the abdominal fat deposition in birds fed low-CP diets during the grower phase. Leu and Val interactions can influence the performance but not the serum characteristics, carcass yield and diameter of muscle fibers of broilers fed low-protein diets. Therefore, it is necessary to consider the dietary Leu content to estimate the ideal level of Val in low-CP diets for optimum broiler performance. © 2016 Poultry Science Association Inc.

Age-related differences in recommended anthropometric cut-off point validity to identify cardiovascular risk factors in ostensibly healthy women

PubMed Central

Björkelund, Cecilia; Guo, Xinxin; Skoog, Ingmar; Bosaeus, Ingvar; Lissner, Lauren

2014-01-01

Aim: To investigate validity of widely recommended anthropometric and total fat percentage cut-off points in screening for cardiovascular risk factors in women of different ages. Methods: A population-based sample of 1002 Swedish women aged 38, 50, 75 (younger, middle-aged and elderly, respectively) underwent anthropometry, health examinations and blood tests. Total fat was estimated (bioimpedance) in 670 women. Sensitivity, specificity of body mass index (BMI; ≥25 and ≥30), waist circumference (WC; ≥80 cm and ≥88 cm) and total fat percentage (TF; ≥35%) cut-off points for cardiovascular risk factors (dyslipidaemias, hypertension and hyperglycaemia) were calculated for each age. Cut-off points yielding high sensitivity together with modest specificity were considered valid. Women reporting hospital admission for cardiovascular disease were excluded. Results: The sensitivity of WC ≥80 cm for one or more risk factors was ~60% in younger and middle-aged women, and 80% in elderly women. The specificity of WC ≥80 cm for one or more risk factors was 69%, 57% and 40% at the three ages (p < .05 for age trends). WC ≥80 cm yielded ~80% sensitivity for two or more risk factors across all ages. However, specificity decreased with increasing age (p < .0001), being 33% in elderly. WC ≥88 cm provided better specificity in elderly women. BMI and TF % cut-off points were not better than WC. Conclusions: Validity of recommended anthropometric cut-off points in screening asymptomatic women varies with age. In younger and middle-age, WC ≥80 cm yielded high sensitivity and modest specificity for two or more risk factors, however, sensitivity for one or more risk factor was less than optimal. WC ≥88 cm showed better validity than WC ≥80 cm in elderly. Our results support age-specific screening cut-off points for women. PMID:25294689

Age-related differences in recommended anthropometric cut-off point validity to identify cardiovascular risk factors in ostensibly healthy women.

PubMed

Subramoney, Sreevidya; Björkelund, Cecilia; Guo, Xinxin; Skoog, Ingmar; Bosaeus, Ingvar; Lissner, Lauren

2014-12-01

To investigate validity of widely recommended anthropometric and total fat percentage cut-off points in screening for cardiovascular risk factors in women of different ages. A population-based sample of 1002 Swedish women aged 38, 50, 75 (younger, middle-aged and elderly, respectively) underwent anthropometry, health examinations and blood tests. Total fat was estimated (bioimpedance) in 670 women. Sensitivity, specificity of body mass index (BMI; ≥25 and ≥30), waist circumference (WC; ≥80 cm and ≥88 cm) and total fat percentage (TF; ≥35%) cut-off points for cardiovascular risk factors (dyslipidaemias, hypertension and hyperglycaemia) were calculated for each age. Cut-off points yielding high sensitivity together with modest specificity were considered valid. Women reporting hospital admission for cardiovascular disease were excluded. The sensitivity of WC ≥80 cm for one or more risk factors was ~60% in younger and middle-aged women, and 80% in elderly women. The specificity of WC ≥80 cm for one or more risk factors was 69%, 57% and 40% at the three ages (p < .05 for age trends). WC ≥80 cm yielded ~80% sensitivity for two or more risk factors across all ages. However, specificity decreased with increasing age (p < .0001), being 33% in elderly. WC ≥88 cm provided better specificity in elderly women. BMI and TF % cut-off points were not better than WC. Validity of recommended anthropometric cut-off points in screening asymptomatic women varies with age. In younger and middle-age, WC ≥80 cm yielded high sensitivity and modest specificity for two or more risk factors, however, sensitivity for one or more risk factor was less than optimal. WC ≥88 cm showed better validity than WC ≥80 cm in elderly. Our results support age-specific screening cut-off points for women. © 2014 the Nordic Societies of Public Health.

A preliminary mechanical property and stress corrosion evaluation of VIM-VAR work strengthened and direct aged Inconel 718 bar material

NASA Technical Reports Server (NTRS)

Montano, J. W.

1987-01-01

This report presents a preliminary mechanical property and stress corrosion evaluation of double melted (vacuum induction melted (VIM), and vacuum arc remelted (VAR)), solution treated, work strengthened and direct aged Inconel 718 alloy bar (5.50 in. (13.97 cm) diameter). Two sets of tensile specimens, one direct single aged and the other direct double aged, were tested at ambient temperature in both the longitudinal and transverse directions. Longitudinal tensile and yield strengths in excess of 200 ksi (1378.96 MPa) and 168 ksi (1158.33 MPa), respectively, were realized at ambient temperature, for the direct double aged specimen. No failures occurred in the single or double edged longitudinal and transverse tensile specimens stressed to 75 and 100 percent of their respective yield strengths and exposed to a salt fog environment for 180 days. Tensile tests performed after the stress corrosion test showed no mechanical property degradation.

Can we predict age at natural menopause using ovarian reserve tests or mother's age at menopause? A systematic literature review.

PubMed

Depmann, Martine; Broer, Simone L; van der Schouw, Yvonne T; Tehrani, Fahimeh R; Eijkemans, Marinus J; Mol, Ben W; Broekmans, Frank J

2016-02-01

This review aimed to appraise data on prediction of age at natural menopause (ANM) based on antimüllerian hormone (AMH), antral follicle count (AFC), and mother's ANM to evaluate clinical usefulness and to identify directions for further research. We conducted three systematic reviews of the literature to identify studies of menopause prediction based on AMH, AFC, or mother's ANM, corrected for baseline age. Six studies selected in the search for AMH all consistently demonstrated AMH as being capable of predicting ANM (hazard ratio, 5.6-9.2). The sole study reporting on mother's ANM indicated that AMH was capable of predicting ANM (hazard ratio, 9.1-9.3). Two studies provided analyses of AFC and yielded conflicting results, making this marker less strong. AMH is currently the most promising marker for ANM prediction. The predictive capacity of mother's ANM demonstrated in a single study makes this marker a promising contributor to AMH for menopause prediction. Models, however, do not predict the extremes of menopause age very well and have wide prediction interval. These markers clearly need improvement before they can be used for individual prediction of menopause in the clinical setting. Moreover, potential limitations for such use include variations in AMH assays used and a lack of correction for factors or diseases affecting AMH levels or ANM. Future studies should include women of a broad age range (irrespective of cycle regularity) and should base predictions on repeated AMH measurements. Furthermore, currently unknown candidate predictors need to be identified.

Age-related factors in the relationship between foot measurements and living stature and body weight.

PubMed

Atamturk, Derya; Duyar, Izzet

2008-11-01

The measurements of feet and footprints are especially important in forensic identification, as they have been used to predict the body height and weight of victims or suspects. It can be observed that the subjects of forensic-oriented studies are generally young adults. That is to say, researchers rarely take into consideration the body's proportional changes with age. Hence, the aim of this study is to generate equations which take age and sex into consideration, when stature and body weight are estimated from foot and footprints dimensions. With this aim in mind, we measured the stature, body weight, foot length and breadth, heel breadth, footprint length and breadth, and footprint heel breadth of 516 volunteers (253 males and 263 females) aged between 17.6 and 82.9 years using standard measurement techniques. The sample population was divided randomly into two groups. Group 1, the study group, consisted of 80% of the sample (n = 406); the remaining 20% were assigned to the cross-validation group or Group 2 (n = 110). In the first stage of the study, we produced equations for estimating stature and weight using a stepwise regression technique. Then, their reliability was tested on Group 2 members. Statistical analyses showed that the ratios of foot dimensions to stature and body weight change considerably with age and sex. Consequently, the regression equations which include these variables yielded more reliable results. Our results indicated that age and sex should be taken into consideration when predicting human body height and weight for forensic purposes.

Zircon U-Pb dating of eclogite from the Qiangtang terrane, north-central Tibet: a case of metamorphic zircon with magmatic geochemical features

NASA Astrophysics Data System (ADS)

Zhai, Qing-guo; Jahn, Bor-ming; Li, Xian-hua; Zhang, Ru-yuan; Li, Qiu-li; Yang, Ya-nan; Wang, Jun; Liu, Tong; Hu, Pei-yuan; Tang, Suo-han

2017-06-01

Zircon is probably the most important mineral used in the dating formation of high-pressure (HP) and ultrahigh-pressure (UHP) metamorphic rocks. The origin of zircon, i.e., magmatic or metamorphic, is commonly assessed by its external morphology, internal structure, mineral inclusions, Th/U ratios and trace element composition. In this study, we present an unusual case of metamorphic zircon from the Qiangtang eclogite, north-central Tibet. The zircon grains contain numerous eclogite-facies mineral inclusions, including omphacite, phengite, garnet and rutile; hence, they are clearly of metamorphic origin. However, they display features similar to common magmatic zircon, including euhedral crystal habit, high Th/U ratios and enriched heavy rare earth elements pattern. We suggest that these zircon grains formed from a different reservoir from that for garnet where no trace elements was present and trace element equilibrium between zircon and garnet was achieved. U-Pb dating of zircon gave an age of 232-237 Ma for the eclogite, and that of rutile yielded a slightly younger age of ca. 217 Ma. These ages are consistent with the reported Lu-Hf mineral isochron and phengite Ar-Ar ages. The zircon U-Pb and mineral Lu-Hf isochron ages are interpreted as the time of the peak eclogite-facies metamorphism, whereas the rutile U-Pb and phengite Ar-Ar ages represent the time of exhumation to the middle crust. Thus, the distinction between metamorphic and magmatic zircons cannot be made using only Th/U ratios and heavy REE compositions for HP-UHP metamorphic rocks of oceanic derivation.

40Ar/39Ar geochronology and paleomagnetism of Independence volcano, Absaroka volcanic supergroup, Beartooth mountains, Montana

USGS Publications Warehouse

Harlan, S.S.; Snee, L.W.; Geissman, J.W.

1996-01-01

Independence volcano is a major volcanic complex in the lower part of the Absaroka Volcanic Supergroup (AVS) of Montana and Wyoming. Recently reported Rb-Sr mineral dates from the complex give apparent ages of 91 and 84 Ma, whereas field relationships and the physical and compositional similarity of the rocks with other dated parts of the AVS indicate an Early to Middle Eocene age for eruption and deposition. To resolve the conflict between age assignments based on stratigraphic correlations and Rb-Sr dates, we report new paleomagnetic data and 40Ar/39Ar dates for Independence volcano. Paleomagnetic data for the stock and an and andesite plug that cuts the stock are well grouped, of reverse polarity, and yield a virtual geomagnetic pole that is essentially identical to Late Cretaceous and Tertiary reference poles. The reverse polarity indicates that the magnetization of these rocks is probably younger than the Cretaceous normal superchron, or less than about 83.5 Ma. Hornblende from a volcanic breccia near the base of the volcanic pile gives a 40Ar/39Ar age of 51.57 Ma, whereas biotites from a dacite sill and a granodiorite stock that forms the core of the volcano give dates that range from 49.96 to 48.50 Ma. These dates record the age of eruption and intrusion of these rocks and clearly show that the age of Independence volcano is Early to Middle Eocene, consistent with stratigraphic relations. We suggest that the Rb-Sr mineral dates from the Independence stock and related intrusions are unreliable.

Influence of spacing and depth of planting to growth and yield of arrowroot (Marantha arundinacea)

NASA Astrophysics Data System (ADS)

Qodliyati, M.; Supriyono; Nyoto, S.

2018-03-01

This study was conducted to determine the optimum spacing and depth of planting to the growth and yield of arrowroot. This research was conducted at the Experimental Field of Agriculture Faculty, Sebelas Maret University on Jumantono, Karanganyar. This research was conducted using Randomized Completely Block Design (RCBD) with two treatment factors of plant spacing and depth of planting. Plant spacing consists of 3 levels, including J1 (30×30 cm), J2 (30×40 cm) and J3 (30×50 cm). Depth of planting consists of 2 levels which are K1 (10 cm) and K2 (20 cm). Data were analyzed by DMRT (Duncan’s Multiple Range Test) at 5% significance level. The results showed that spacing of 30×50 cm have significantly higher plant height, tuber (common names of rhizome) length, and tuber weight per plant. The depth of 20 cm gives a higher yield on the number of tubers per plant and tuber weight per plot variables. Both treatments have no significant interaction on growth and yield.

Fall rice straw management and winter flooding treatment effects on a subsequent soybean crop

USGS Publications Warehouse

Anders, M.M.; Windham, T.E.; McNew, R.W.; Reinecke, K.J.

2005-01-01

The effects of fall rice (Oryza sativa L.) straw management and winter flooding on the yield and profitability of subsequent irrigated and dryland soybean [Glycine max (L.) Merr.] crops were studied for 3 years. Rice straw treatments consisted of disking, rolling, or standing stubble. Winter flooding treatments consisted of maintaining a minimum water depth of 10 cm by pumping water when necessary, impounding available rainfall, and draining fields to prevent flooding. The following soybean crop was managed as a conventional-tillage system or no-till system. Tillage system treatments were further divided into irrigated or dryland. Results indicated that there were no significant effects from either fall rice straw management or winter flooding treatments on soybean seed yields. Soybean seed yields for, the conventional tillage system were significantly greater than those for the no-till system for the first 2 yrs and not different in the third year. Irrigated soybean seed yields were significantly greater than those from dryland plots for all years. Net economic returns averaged over the 3 yrs were greatest ($390.00 ha-1) from the irrigated no-till system.

Holocene age of the Yuha burial: Direct radiocarbon determinations by accelerator mass spectrometry

USGS Publications Warehouse

Stafford, Thomas W.; Jull, A.J.T.; Zabel, T.H.; Donahue, D.J.; Duhamel, R.C.; Brendel, K.; Haynes, C.V.; Bischoff, J.L.; Payen, L.A.; Taylor, R.E.

1984-01-01

The view that human populations may not have arrived in the Western Hemisphere before about 12,000 radiocarbon yr BP1,2 has been challenged by claims of much greater antiquity for a small number of archaeological sites and human skeleton samples. One such site is the Homo sapiens sapiens cairn burial excavated in 1971 from the Yuha desert, Imperial County, California3-5. Radiocarbon analysis of caliche coating one of the bones of the skeleton yielded a radiocarbon age of 21,500??1,000 yr BP4, while radiocarbon and uranium series analyses of caliche coating a cairn boulder yielded ages of 22,125??400 and 19,000??3,000 yr BP, respectively5. The late Pleistocene age assignment to the Yuha burial has been challenged by comparing the cultural context of the burial with other cairn burials in the same region6, on the basis of the site's geomorphological context and from radiocarbon analyses of soil caliches. 7,8 In rebuttal, arguments in defence of the original age assignment have been presented9,10 as well as an amino acid racemization analysis on the Yuha skeleton indicating an age of 23,600??2,600 yr BP11. The tandem accelerator mass spectrometer at the University of Arizona has now been used to measure the ratio of 14C/13C in several organic and inorganic fractions of post-cranial bone from the Yuha H. sapiens sapiens skeleton. Isotope ratios from six chemical fractions all yielded radiocarbon ages for the skeleton of less than 4,000 yr BP. These results indicate that the Yuha skeleton is of Holocene age, in agreement with the cultural context of the burial, and in disagreement with the previously assigned Pleistocene age of 19,000-23,000 yr. ?? 1984 Nature Publishing Group.

Development and Validation of the Bicultural Youth Acculturation Questionnaire

PubMed Central

Kukaswadia, Atif; Janssen, Ian; Pickett, William; Bajwa, Jasmine; Georgiades, Katholiki; Lalonde, Richard N.; Quon, Elizabeth C.; Safdar, Saba; Pike, Ian

2016-01-01

Objectives Acculturation is a multidimensional process involving changes in behaviour and beliefs. Questionnaires developed to measure acculturation are typically designed for specific ethnic populations and adult experiences. This study developed a questionnaire that measures acculturation among ethnically diverse populations of youth that can be included as a module in population surveys. Methods Questionnaires measuring acculturation in youth were identified in the literature. The importance of items from the existing questionnaires was determined using a Delphi process and this informed the development of our questionnaire. The questionnaire was then pilot tested using a sample of 248 Canadians aged 18–25 via an online system. Participants identified as East and South East Asian (27.8%), South Asian (17.7%) and Black (13.7%). The majority were 1st (33.5%) or 2nd generation immigrants (52.0%). After redundant items were eliminated, exploratory factor analysis grouped items into domains, and, for each domain, internal consistency, and convergent validity with immigrant generation then age at immigration estimated. A subset of participants re-completed the questionnaire for reliability estimation. Results The literature review yielded 117 articles that used 13 questionnaires with a total of 440 questions. The Delphi process reduced these to 32 questions. Pilot testing occurred in 248 Canadians aged 18–25. Following item reduction, 16 questions in three domains remained: dominant culture, heritage language, and heritage culture. All had good internal consistency (Cronbach’s alphas > .75). The mean dominant domain score increased with immigrant generation (1st generation: 3.69 (95% CI: 3.49–3.89), 2nd: 4.13 (4.00–4.26), 3rd: 4.40 (4.19–4.61)), and mean heritage language score was higher among those who immigrated after age 12 than before (p = .0001), indicative of convergent validity. Conclusions This Bicultural Youth Acculturation Questionnaire has demonstrated validity. It can be incorporated into population health surveys to elucidate the impact of acculturation on health outcomes among bicultural youth. PMID:27557080

Development and Validation of the Bicultural Youth Acculturation Questionnaire.

PubMed

Kukaswadia, Atif; Janssen, Ian; Pickett, William; Bajwa, Jasmine; Georgiades, Katholiki; Lalonde, Richard N; Quon, Elizabeth C; Safdar, Saba; Pike, Ian

2016-01-01

Acculturation is a multidimensional process involving changes in behaviour and beliefs. Questionnaires developed to measure acculturation are typically designed for specific ethnic populations and adult experiences. This study developed a questionnaire that measures acculturation among ethnically diverse populations of youth that can be included as a module in population surveys. Questionnaires measuring acculturation in youth were identified in the literature. The importance of items from the existing questionnaires was determined using a Delphi process and this informed the development of our questionnaire. The questionnaire was then pilot tested using a sample of 248 Canadians aged 18-25 via an online system. Participants identified as East and South East Asian (27.8%), South Asian (17.7%) and Black (13.7%). The majority were 1st (33.5%) or 2nd generation immigrants (52.0%). After redundant items were eliminated, exploratory factor analysis grouped items into domains, and, for each domain, internal consistency, and convergent validity with immigrant generation then age at immigration estimated. A subset of participants re-completed the questionnaire for reliability estimation. The literature review yielded 117 articles that used 13 questionnaires with a total of 440 questions. The Delphi process reduced these to 32 questions. Pilot testing occurred in 248 Canadians aged 18-25. Following item reduction, 16 questions in three domains remained: dominant culture, heritage language, and heritage culture. All had good internal consistency (Cronbach's alphas > .75). The mean dominant domain score increased with immigrant generation (1st generation: 3.69 (95% CI: 3.49-3.89), 2nd: 4.13 (4.00-4.26), 3rd: 4.40 (4.19-4.61)), and mean heritage language score was higher among those who immigrated after age 12 than before (p = .0001), indicative of convergent validity. This Bicultural Youth Acculturation Questionnaire has demonstrated validity. It can be incorporated into population health surveys to elucidate the impact of acculturation on health outcomes among bicultural youth.

Dietary Patterns and 10-year (2002-2012) Incidence of Type 2 Diabetes: Results from the ATTICA Cohort Study

PubMed Central

Koloverou, Efi; Panagiotakos, Demosthenes B.; Georgousopoulou, Ekavi N.; Grekas, Athanasios; Christou, Aimilia; Chatzigeorgiou, Michail; Chrysohoou, Christina; Tousoulis, Dimitrios; Stefanadis, Christodoulos; Pitsavos, Christos; ATTICA Study Group

2016-01-01

AIM: To identify dietary patterns among apparently healthy individuals and to determine their long-term effect on diabetes incidence. METHODS: During 2001-2002, a random sample of 3,042 men and women (18-89 years old), living in greater Athens, was randomly selected to participate in the study. During 2011-2012, the 10-year follow-up was performed in 2,583 participants (15% drop-out rate). After excluding participants with diabetes at baseline and those for whom no information on diabetes status was available at follow-up, the working sample consisted of 1,485 participants. Dietary habits were assessed by means of a validated semi-quantitative, food frequency questionnaire. Factor analysis was performed to extract dietary patterns from 18 food groups. RESULTS: Diabetes diagnosis at follow-up was made in 191 participants, yielding an incidence rate of 12.9%. Six factors (i.e. dietary patterns) were identified that explained 54% of the variation in consumption. After adjusting for major confounders, and stratification by age-group, logistic regression revealed that the most healthful pattern consisted of the consumption of fruits, vegetables, legumes, bread, rusk, and pasta which reduced the 10-year diabetes risk by 40%, among participants aged 45-55 years. The association reached marginal statistical significance (95% CI: 0.34, 1.07), while no significant association was observed for the other age-groups. When the analysis was additionally adjusted for carbohydrate percentage, statistical significance was lost completely, suggesting a possibly mediating effect of this macronutrient. CONCLUSIONS: The results confirm the potentially protective effect of a plant-based dietary pattern in the primary prevention of diabetes, in particular among middle-aged people. Carbohydrate content may be a specific factor in this relationship; other micronutrients found in plant-based food groups may also play a role. PMID:28394951

Frictional `non-aging' of fault mirror surfaces?: Insight from friction experiments on Carrara marble

NASA Astrophysics Data System (ADS)

Park, Y.; Ree, J. H.; Hirose, T.

2016-12-01

Mirror-like fault surfaces (or fault mirror: FM) have recently been suggested as a precursor of unstable slip (thus indicative of seismic slip). Frictional aging of fault surfaces (increase in static friction during interseismic period) is a common phenomenon of fault surfaces, resulting from increase in contact area or in bond strength between asperities with time. Despite the importance of FM in earthquake faulting, the frictional-aging behavior of FM has never been studied. To understand the frictional-aging behavior of FM, slide-hold-slide friction experiments were done on carbonate FM and powdered gouge of former carbonate FM (PG hereafter) using low-to-high-velocity-rotary-shear apparatus, at a slip rate of 1 μm s-1 a normal stress of 1.5 MPa, room temperature and room humidity condition. The sheared PG specimens showed a logarithmic positive relationship between static friction and holding time, consistent with Dieterich-type healing behavior. In contrast, the sheared FM specimens showed little effect of holding time on static friction. The slip surface of FM specimens consists of densely-packed and sintered nano-particles while that of PG specimens is composed of loose nano-particles. It has been known that yield strength of a material increases dramatically with size-decreasing grains being nano-particles. Since FM is a layer of densely-packed and sintered nanoparticles, enhanced strength of FM may inhibit growth of real contact area of fault surfaces during hold time. Furthermore, sintered particles composing FM have less pore space than loose gouge layer, and thus there would be a less chance of strengthening by pore space reduction, inter-particle meniscus formation or water adsorption onto the particles surface in the FM layer. Our preliminary result suggests that carbonate FM's may impede the recovery of fault strength during interseismic period, resulting in less possibility of earthquake nucleation. Reduced frictional healing may be a common phenomenon of FM's in other materials too once they are composed of sintered nano-particles.

Loss of p21{sup Sdi1} expression in senescent cells after DNA damage accompanied with increase of miR-93 expression and reduced p53 interaction with p21{sup Sdi1} gene promoter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, Ok Ran; Lim, In Kyoung, E-mail: iklim@ajou.ac.kr

2011-04-08

Highlights: {yields} Reduced p21 expression in senescent cells treated with DNA damaging agents. {yields} Increase of [{sup 3}H]thymidine and BrdU incorporations in DNA damaged-senescent cells. {yields} Upregulation of miR-93 expression in senescent cells in response to DSB. {yields} Failure of p53 binding to p21 promoter in senescent cells in response to DSB. {yields} Molecular mechanism of increased cancer development in aged than young individuals. -- Abstract: To answer what is a critical event for higher incidence of tumor development in old than young individuals, primary culture of human diploid fibroblasts were employed and DNA damage was induced by doxorubicin ormore » X-ray irradiation. Response to the damage was different between young and old cells; loss of p21{sup sdi1} expression in spite of p53{sup S15} activation in old cells along with [{sup 3}H]thymidine and BrdU incorporation, but not in young cells. The phenomenon was confirmed by other tissue fibroblasts obtained from different donor ages. Induction of miR-93 expression and reduced p53 binding to p21 gene promoter account for loss of p21{sup sdi1} expression in senescent cells after DNA damage, suggesting a mechanism of in vivo carcinogenesis in aged tissue without repair arrest.« less

Ar-40/Ar-39 ages and cosmic ray exposure ages of Apollo 14 samples.

NASA Technical Reports Server (NTRS)

Turner, G.; Huneke, J. C.; Podosek, F. A.; Wasserburg, G. J.

1971-01-01

We have used the Ar-40/Ar-39 dating technique on eight samples of Apollo 14 rocks (14053, 14310), breccia fragments (14321), and soil fragments (14001, 14167). The large basalt fragments give reasonable Ar-40/Ar-39 release patterns and yield well defined crystallization ages of 3.89-3.95 aeons. Correlation of the Ar-40/Ar-39 release patterns with Ar-39/Ar-37 patterns showed that the low temperature fractions with high radiogenic argon loss came from K-rich phases. A highly shocked sample and fragments included in the breccia yield complex release patterns with a low temperature peak. The total argon age of these fragments is 3.95 aeons. Cosmic ray exposure ages on these samples are obtained from the ratio of spallogenic Ar-38 to reactor induced Ar-37 and show a distinct grouping of low exposure ages of 26 m.y. correlated with Cone crater. Other samples have exposure ages of more than 260 m.y. and identify material with a more complex integrated cosmic age exposure history.

A Kinematic Description of the Temporal Characteristics of Jaw Motion for Early Chewing: Preliminary Findings

PubMed Central

Wilson, Erin M.; Green, Jordan R.; Weismer, Gary

2013-01-01

Purpose The purpose of this investigation was to describe age- and consistency-related changes in the temporal characteristics of chewing in typically-developing children between 4 – 35 months of age and adults using high-resolution optically-based motion capture technology. Method Data were collected from a total of 60 participants (48 children, 12 adults) across five age ranges (beginners, 7-months, 12-months, 35-months, and adults); each age group included 12 participants. Three different food consistencies were trialed as appropriate. The data were analyzed to assess changes in chewing rate, chewing sequence duration, and a measure of the estimated number of chewing cycles. Results The results revealed both age- and consistency-related changes in chewing rate, sequence duration, and the estimated number of chewing cycles with consistency differences affecting masticatory timing in children as young as 7-months of age. Chewing rate varied as a function of age and consistency and chewing sequence duration was shorter for adults than children regardless of consistency type. Additionally, the results from the estimated number of chewing cycles measure suggests that chewing effectiveness increased with age; this measure was also dependent on consistency type. Conclusions The findings suggest that the different temporal chewing variables follow distinct developmental trajectories and are consistency-dependent in children as young as 7-months of age. Clinical implications are detailed. PMID:22223889

Growth and yield model for non-timber forest product of kemenyan (Styrax sumatrana J.J. Sm) in Tapanuli, North Sumatra

NASA Astrophysics Data System (ADS)

Aswandi; Kholibrina, C. R.

2018-02-01

Kemenyan is Styrax tree resin, the main of non-timber forest product commodity in Lake Toba catchment area, North Sumatra since hundreds years ago. However, there are lack of information about the growth and yield prediction for this tree species. The objective of study is to construct the growth and yield models for Styrax sumatrana in Tapanuli region, North Sumatra. Measurement data from 20 temporary plots were used to formulate stand diameter and height equations, and to project the incense production. The highest Current Annual Increment (CAI) of diameter occurs in the stand’s age 21 to 25 years (1.00 cm/year). The growth of diameter declines significantly to 0.48 cm/year in age 46 to 50 years, and decrease to 0.26 cm/year at age 50 years up. The intersection of CAI and MAI curves occur in stand age 31 to 35 years. It shows that the optimal growth occurs in this period. The average of incenses production was 318.59 g/tree/year. The optimum incense production was achieved when the diameter growth was maximal and tapping scars accumulation was limited.

Large-Scale, Long-Lived Subduction of Ultrahigh-Pressure Terranes: Western Gneiss Region, Norway

NASA Astrophysics Data System (ADS)

Kylander-Clark, A. R.; Hacker, B. R.; Johnson, C. M.; Beard, B. L.; Corfu, F.; Mahlen, N. J.

2007-12-01

Recent Lu-Hf and Sm-Nd ages of garnets and a U-Pb age of zircon of eclogites from the Western Gneiss Region (WGR) ultrahigh-pressure (UHP) terrane, Norway, demonstrate that eclogite-facies metamorphism occurred over a large area (60,000 km2) for an unexpectedly long time. This observation stands in stark contrast to the general belief that continental subduction, and attendant (U)HP metamorphism, occurs over short timescales. Four HP eclogites (~700-800°C, ~2.0-2.5 GPa) from the central WGR yielded equivalent Lu-Hf ages of ~416 Ma; three of these samples gave Sm-Nd ages of ~400 Ma. Given the distribution coefficients for Lu and Sm, the older Lu-Hf ages reflect prograde growth, but are younger than the initiation of garnet crystallization. The younger Sm-Nd ages represent either eclogite-facies cooling through the blocking temperature of the Sm-Nd system or an 'average' age of garnet growth. Both cases imply >16 m.y. of eclogite- facies conditions. Two UHP eclogites (~750-850°C, ~3 GPa) from the same region yielded significantly younger, but equivalent Lu-Hf and Sm-Nd ages of ~380 Ma, which likely indicate passage through the blocking temperature of both systems up to 20 m.y. after the HP eclogites had passed through the blocking temperature. Because these eclogites are unretrogressed, their ages are the youngest known for eclogite stability in the WGR. An eclogite from the northern WGR yielded a Sm-Nd age of 413.9 ± 3.7 Ma. This could represent a different HP history than that of the central WGR: U/Pb ages in the north are also ~15 m.y. older. Two HP (~650°C, ~2 GPa) eclogites from the southern WGR yielded Lu-Hf ages of 410.2 ± 3.1 and 427.5 ± 7.7 Ma, indicating a similar garnet growth history to the central WGR eclogites. A retrogressed eclogite from the undated eastern portion of the WGR gave a 206Pb/238U age of 408.0 ± 1.7 Ma. Thermal models mirror results from similar studies (Roselle et al., 2002), and confirm that slow subduction likely produced the P-T-t record observed in the WGR. For subduction of a continent into a formerly Andean-style subduction zone, Calculated temperatures of ~700-800°C are reached at 100 km depth only at burial rates slower than 4 mm/yr. These same temperatures are achieved with slow burial (4-7 mm/yr) during intracontinental subduction.

Coupling constant for N*(1535)N{rho}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie Jujun; Graduate University of Chinese Academy of Sciences, Beijing 100049; Wilkin, Colin

2008-05-15

The value of the N*(1535)N{rho} coupling constant g{sub N*N{rho}} derived from the N*(1535){yields}N{rho}{yields}N{pi}{pi} decay is compared with that deduced from the radiative decay N*(1535){yields}N{gamma} using the vector-meson-dominance model. On the basis of an effective Lagrangian approach, we show that the values of g{sub N*N{rho}} extracted from the available experimental data on the two decays are consistent, though the error bars are rather large.

Estimating the impact of mineral aerosols on crop yields in food insecure regions using statistical crop models

NASA Astrophysics Data System (ADS)

Hoffman, A.; Forest, C. E.; Kemanian, A.

2016-12-01

A significant number of food-insecure nations exist in regions of the world where dust plays a large role in the climate system. While the impacts of common climate variables (e.g. temperature, precipitation, ozone, and carbon dioxide) on crop yields are relatively well understood, the impact of mineral aerosols on yields have not yet been thoroughly investigated. This research aims to develop the data and tools to progress our understanding of mineral aerosol impacts on crop yields. Suspended dust affects crop yields by altering the amount and type of radiation reaching the plant, modifying local temperature and precipitation. While dust events (i.e. dust storms) affect crop yields by depleting the soil of nutrients or by defoliation via particle abrasion. The impact of dust on yields is modeled statistically because we are uncertain which impacts will dominate the response on national and regional scales considered in this study. Multiple linear regression is used in a number of large-scale statistical crop modeling studies to estimate yield responses to various climate variables. In alignment with previous work, we develop linear crop models, but build upon this simple method of regression with machine-learning techniques (e.g. random forests) to identify important statistical predictors and isolate how dust affects yields on the scales of interest. To perform this analysis, we develop a crop-climate dataset for maize, soybean, groundnut, sorghum, rice, and wheat for the regions of West Africa, East Africa, South Africa, and the Sahel. Random forest regression models consistently model historic crop yields better than the linear models. In several instances, the random forest models accurately capture the temperature and precipitation threshold behavior in crops. Additionally, improving agricultural technology has caused a well-documented positive trend that dominates time series of global and regional yields. This trend is often removed before regression with traditional crop models, but likely at the cost of removing climate information. Our random forest models consistently discover the positive trend without removing any additional data. The application of random forests as a statistical crop model provides insight into understanding the impact of dust on yields in marginal food producing regions.

Molybdenite Re-Os, zircon U-Pb dating and Lu-Hf isotopic analysis of the Xiaerchulu Au deposit, Inner Mongolia Province, China

NASA Astrophysics Data System (ADS)

Wang, Jia-xin; Nie, Feng-Jun; Zhang, Xue-ni; Jiang, Si-hong

2016-09-01

The Xiaerchulu Au deposit, located in the Southern Orogenic Belt (SOB) of Western Inner Mongolia (WIM), is hosted in an Early Permian (271-261 Ma) volcanic-plutonic sequence. Mineralization took place in silicified biotite granites or along the contact zone between the Neoproterozoic Baiyinbaolage Group and the biotite granite. In order to constrain the timing of the Xiaerchulu mineralization and discuss the petrogenesis of the hosting granites, molybdenite Re-Os, and zircon U-Pb and, Lu-Hf, and REE, geochemical, and Sr-Nd isotopic studies were completed in this study. We measured Re-Os isotopes of six molybdenite samples from the main ore body, which yielded a weighted average model age of 261.7 ± 1.5 Ma with a MSWD of 0.55, indicating that the time of mineralization was at ca. 262 Ma. High precision U-Pb dating for the studied granites yields Permian 206Pb/238U ages ranging from 271 to 269 Ma. These age data confirm that both the intrusion and related mineralization were initiated in Early Permian period. These granites are strongly peraluminous with A/CNK = 1.11-1.12, high SiO2-K2O contents, as well as containing biotite and muscovite, indicating a petrogenesis of typical S-type granites, the above consideration is also consistent with the result of discrimination diagrams. The Re contents of molybdenite, εNd(t), and zircon εHf(t), as well as the 176Hf/177Hf values of the granites, fall into the ranges from 1.153 to 2.740 μg/g, - 11.1 to - 9.3, - 8.8 to - 0.9, and 0.282358 to 0.282688, respectively. All of this evidence suggests that the metals were derived from a predominantly crustal source, the granites originated from crust in an extensional setting, and the rejuvenation of the continent may have play an important role during the ore-forming processes of the Early Permian epoch.

A meta-analysis on progressive atrophy in intractable temporal lobe epilepsy

PubMed Central

Caciagli, Lorenzo; Bernasconi, Andrea; Wiebe, Samuel; Koepp, Matthias J.; Bernasconi, Neda

2017-01-01

Objective: It remains unclear whether drug-resistant temporal lobe epilepsy (TLE) is associated with cumulative brain damage, with no expert consensus and no quantitative syntheses of the available evidence. Methods: We conducted a systematic review and meta-analysis of MRI studies on progressive atrophy, searching PubMed and Ovid MEDLINE databases for cross-sectional and longitudinal quantitative MRI studies on drug-resistant TLE. Results: We screened 2,976 records and assessed eligibility of 248 full-text articles. Forty-two articles met the inclusion criteria for quantitative evaluation. We observed a predominance of cross-sectional studies, use of different clinical indices of progression, and high heterogeneity in age-control procedures. Meta-analysis of 18/1 cross-sectional/longitudinal studies on hippocampal atrophy (n = 979 patients) yielded a pooled effect size of r = −0.42 for ipsilateral atrophy related to epilepsy duration (95% confidence interval [CI] −0.51 to −0.32; p < 0.0001; I2 = 65.22%) and r = −0.35 related to seizure frequency (95% CI −0.47 to −0.22; p < 0.0001; I2 = 61.97%). Sensitivity analyses did not change the results. Narrative synthesis of 25/3 cross-sectional/longitudinal studies on whole brain atrophy (n = 1,504 patients) indicated that >80% of articles reported duration-related progression in extratemporal cortical and subcortical regions. Detailed analysis of study design features yielded low to moderate levels of evidence for progressive atrophy across studies, mainly due to dominance of cross-sectional over longitudinal investigations, use of diverse measures of seizure estimates, and absence of consistent age control procedures. Conclusions: While the neuroimaging literature is overall suggestive of progressive atrophy in drug-resistant TLE, published studies have employed rather weak designs to directly demonstrate it. Longitudinal multicohort studies are needed to unequivocally differentiate aging from disease progression. PMID:28687722

Provenance history of detrital diamond deposits, West Coast of Namaqualand, South Africa

NASA Astrophysics Data System (ADS)

Phillips, David; Harris, Jeffrey W.; de Wit, Michiel C. J.; Matchan, Erin L.

2018-05-01

The West Coast of Namaqualand in South Africa hosts extensive detrital diamond deposits, but considerable debate exists as to the provenance of these diamonds. Some researchers have suggested derivation of the diamonds from Cretaceous-Jurassic kimberlites (also termed Group I kimberlites) and orangeites (also termed Group II kimberlites) located on the Kaapvaal Craton. However, others favour erosion of diamonds from the ca.300 Ma Dwyka Group sediments, with older, pre-Karoo kimberlites being the original source(s). Previous work has demonstrated that 40Ar/39Ar analyses of clinopyroxene inclusions, extracted from diamonds, yield ages approaching the time(s) of source kimberlite emplacement, which can be used to constrain the provenance of placer diamond deposits. In the current study, 40Ar/39Ar analyses were conducted on clinopyroxene inclusions from two similar batches of Namaqualand detrital diamonds, yielding (maximum) ages ranging from 117.5 ± 43.6 Ma to 3684 ± 191 Ma (2σ) and 120.6 ± 15.4 Ma to 688.8 ± 4.9 Ma (2σ), respectively. The vast majority of inclusions (88%) produced ages younger than 500 Ma, indicating that most Namaqualand diamonds originated from Cretaceous-Jurassic kimberlites/orangeites, with few, if any, derived from the Dwyka tillites. The provenance of the Namaqualand diamonds from ca.115-200 Ma orangeites is consistent with Late Cretaceous paleo-drainage reconstructions, as these localities could have been sampled by the `paleo-Karoo' River and transported to the West Coast via an outlet close to the current Olifants River mouth. At ca.90 Ma, this drainage system appears to have been captured by the `paleo-Kalahari' River, a precursor to the modern Orange River system. This latter drainage is considered to have transported diamonds eroded from both ca.80-90 Ma kimberlites and ca.115-200 Ma orangeites to the West Coast, which were subsequently reworked along the Namibian coast, forming additional placer deposits.

Timing and conditions of peak metamorphism and cooling across the Zimithang Thrust, Arunachal Pradesh, India

NASA Astrophysics Data System (ADS)

Warren, Clare J.; Singh, Athokpam K.; Roberts, Nick M. W.; Regis, Daniele; Halton, Alison M.; Singh, Rajkumar B.

2014-07-01

The Zimithang Thrust juxtaposes two lithotectonic units of the Greater Himalayan Sequence in Arunachal Pradesh, NE India. Monazite U-Pb, muscovite 40Ar/39Ar and thermobarometric data from rocks in the hanging and footwall constrain the timing and conditions of their juxtaposition across the structure, and their subsequent cooling. Monazite grains in biotite-sillimanite gneiss in the hanging wall yield LA-ICP-MS U-Pb ages of 16 ± 0.2 to 12.7 ± 0.4 Ma. A schistose gneiss within the high strain zone yields overlapping-to-younger monazite ages of 14.9 ± 0.3 to 11.5 ± 0.3 Ma. Garnet-staurolite-mica schists in the immediate footwall yield older monazite ages of 27.3 ± 0.6 to 17.1 ± 0.2 Ma. Temperature estimates from Ti-in-biotite and garnet-biotite thermometry suggest similar peak temperatures were achieved in the hanging and footwalls (~ 525-650 °C). Elevated temperatures of ~ 700 °C appear to have been reached in the high strain zone itself and in the footwall further from the thrust. Single grain fusion 40Ar/39Ar muscovite data from samples either side of the thrust yield ages of ~ 7 Ma, suggesting that movement along the thrust juxtaposed the two units by the time the closure temperature of Ar diffusion in muscovite had been reached. These data confirm previous suggestions that major orogen-parallel out-of-sequence structures disrupt the Greater Himalayan Sequence at different times during Himalayan evolution, and highlight an eastwards-younging trend in 40Ar/39Ar muscovite cooling ages at equivalent structural levels along Himalayan strike.

Recognition of > or = 3850 Ma water-lain sediments in West Greenland and their significance for the early Archaean Earth.

PubMed

Nutman, A P; Mojzsis, S J; Friend, C R

1997-01-01

A layered body of amphibolite, banded iron formation (BIF), and ultramafic rocks from the island of Akilia, southern West Greenland, is cut by a quartz-dioritic sheet from which SHRIMP zircon 206Pb/207Pb weighted mean ages of 3865 +/- 11 Ma and 3840 +/- 8 Ma (2 sigma) can be calculated by different approaches. Three other methods of assessing the zircon data yield ages of >3830 Ma. The BIFs are interpreted as water-lain sediments, which with a minimum age of approximately 3850 Ma, are the oldest sediments yet documented. These rocks provide proof that by approximately 3850 Ma (1) there was a hydrosphere, supporting the chemical sedimentation of BIF, and that not all water was stored in hydrous minerals, and (2) that conditions satisfying the stability of liquid water imply surface temperatures were similar to present. Carbon isotope data of graphitic microdomains in apatite from the Akilia island BIF are consistent with a bio-organic origin (Mojzsis et al. 1996), extending the record of life on Earth to >3850 Ma. Life and surface water by approximately 3850 Ma provide constraints on either the energetics or termination of the late meteoritic bombardment event (suggested from the lunar cratering record) on Earth.

Changes in Neuroticism Following Trauma Exposure

PubMed Central

Ogle, Christin M.; Rubin, David C.; Siegler, Ilene C.

2014-01-01

Objective Using longitudinal data, the present study examined change in midlife neuroticism following trauma exposure. Method Our primary analyses included 670 participants (M age = 60.55, 65.22% male, 99.70% Caucasian) who completed the NEO Personality Inventory at mean age 42 and 50 and reported their lifetime exposure to traumatic events approximately 10 years later. Results No differences in pre-and post-trauma neuroticism scores were found among individuals who experienced all of their lifetime traumas in the interval between the personality assessments. Results were instead consistent with normative age-related declines in neuroticism throughout adulthood. Furthermore, longitudinal changes in neuroticism scores did not differ between individuals with and without histories of midlife trauma exposure. Examination of change in neuroticism following life-threatening traumas yielded a comparable pattern of results. Analysis of facet-level scores largely replicated findings from the domain scores. Supplemental analyses indicated that individuals exposed to life-threatening traumas in childhood or adolescence reported higher midlife neuroticism than individuals who experienced severe traumas in adulthood. Conclusions Overall, our findings suggest that neuroticism does not reliably change following exposure to traumatic events in middle adulthood. Life-threatening traumatic events encountered early in life may have a more pronounced impact on adulthood personality than recent traumatic events. PMID:23550961

The Aggradational Successions of the Aniene River Valley in Rome: Age Constraints to Early Neanderthal Presence in Europe

PubMed Central

Ceruleo, Piero; Pandolfi, Luca; Petronio, Carmelo; Rolfo, Mario F.; Salari, Leonardo

2017-01-01

We revise the chronostratigraphy of several sedimentary successions cropping out along a 5 km-long tract of the Aniene River Valley in Rome (Italy), which yielded six hominin remains previously attributed to proto- or archaic Neanderthal individuals, as well as a large number of lithic artefacts showing intermediate characteristics somewhere between the local Acheulean and Mousterian cultures. Through a method of correlation of aggradational successions with post-glacial sea-level rises, relying on a large set of published 40Ar/39Ar ages of interbedded volcanic deposits, we demonstrate that deposition of the sediments hosting the human remains spans the interval 295–220 ka. This is consistent with other well constrained ages for lithic industries recovered in England, displaying transitional features from Lower to Middle Paleolithic, suggesting the appearance of Mode 3 during the MIS 9-MIS 8 transition. Moreover, the six human bone fragments recovered in the Aniene Valley should be regarded as the most precisely dated and oldest hominin remains ascribable to Neanderthal-type individuals in Europe, discovered to date. The chronostratigraphic study presented here constitutes the groundwork for addressing re-analysis of these remains and of their associated lithic industries, in the light of their well-constrained chronological picture. PMID:28125602

Recognition of > or = 3850 Ma water-lain sediments in West Greenland and their significance for the early Archaean Earth

NASA Technical Reports Server (NTRS)

Nutman, A. P.; Mojzsis, S. J.; Friend, C. R.; Bada, J. L. (Principal Investigator)

1997-01-01

A layered body of amphibolite, banded iron formation (BIF), and ultramafic rocks from the island of Akilia, southern West Greenland, is cut by a quartz-dioritic sheet from which SHRIMP zircon 206Pb/207Pb weighted mean ages of 3865 +/- 11 Ma and 3840 +/- 8 Ma (2 sigma) can be calculated by different approaches. Three other methods of assessing the zircon data yield ages of >3830 Ma. The BIFs are interpreted as water-lain sediments, which with a minimum age of approximately 3850 Ma, are the oldest sediments yet documented. These rocks provide proof that by approximately 3850 Ma (1) there was a hydrosphere, supporting the chemical sedimentation of BIF, and that not all water was stored in hydrous minerals, and (2) that conditions satisfying the stability of liquid water imply surface temperatures were similar to present. Carbon isotope data of graphitic microdomains in apatite from the Akilia island BIF are consistent with a bio-organic origin (Mojzsis et al. 1996), extending the record of life on Earth to >3850 Ma. Life and surface water by approximately 3850 Ma provide constraints on either the energetics or termination of the late meteoritic bombardment event (suggested from the lunar cratering record) on Earth.

Olfactory Impairment in Chronic Rhinosinusitis Using Threshold, Discrimination, and Identification Scores

PubMed Central

Kohli, Preeti; Storck, Kristina A.; Schlosser, Rodney J.

2016-01-01

Differences in testing modalities and cut-points used to define olfactory dysfunction contribute to the wide variability in estimating the prevalence of olfactory dysfunction in chronic rhinosinusitis (CRS). The aim of this study is to report the prevalence of olfactory impairment using each component of the Sniffin’ Sticks test (threshold, discrimination, identification, and total score) with age-adjusted and ideal cut-points from normative populations. Patients meeting diagnostic criteria for CRS were enrolled from rhinology clinics at a tertiary academic center. Olfaction was assessed using the Sniffin’ Sticks test. The study population consisted of 110 patients. The prevalence of normosmia, hyposmia, and anosmia using total Sniffin’ Sticks score was 41.8%, 20.0%, and 38.2% using age-appropriate cut-points and 20.9%, 40.9%, and 38.2% using ideal cut-points. Olfactory impairment estimates for each dimension mirrored these findings, with threshold yielding the highest values. Threshold, discrimination, and identification were also found to be significantly correlated to each other (P < 0.001). In addition, computed tomography scores, asthma, allergy, and diabetes were found to be associated with olfactory dysfunction. In conclusion, the prevalence of olfactory dysfunction is dependent upon olfactory dimension and if age-adjusted cut-points are used. The method of olfactory testing should be chosen based upon specific clinical and research goals. PMID:27469973

A consistent transported PDF model for treating differential molecular diffusion

NASA Astrophysics Data System (ADS)

Wang, Haifeng; Zhang, Pei

2016-11-01

Differential molecular diffusion is a fundamentally significant phenomenon in all multi-component turbulent reacting or non-reacting flows caused by the different rates of molecular diffusion of energy and species concentrations. In the transported probability density function (PDF) method, the differential molecular diffusion can be treated by using a mean drift model developed by McDermott and Pope. This model correctly accounts for the differential molecular diffusion in the scalar mean transport and yields a correct DNS limit of the scalar variance production. The model, however, misses the molecular diffusion term in the scalar variance transport equation, which yields an inconsistent prediction of the scalar variance in the transported PDF method. In this work, a new model is introduced to remedy this problem that can yield a consistent scalar variance prediction. The model formulation along with its numerical implementation is discussed, and the model validation is conducted in a turbulent mixing layer problem.

Strength Differential Measured in Inconel 718: Effects of Hydrostatic Pressure Studied

NASA Technical Reports Server (NTRS)

Lewandowski, John J.; Wesseling, Paul; Prabhu, Nishad S.; Larose, Joel; Lissenden, Cliff J.; Lerch, Bradley A.

2003-01-01

Aeropropulsion components, such as disks, blades, and shafts, are commonly subjected to multiaxial stress states at elevated temperatures. Experimental results from loadings as complex as those experienced in service are needed to help guide the development of accurate viscoplastic, multiaxial deformation models that can be used to improve the design of these components. During a recent study on multiaxial deformation (ref. 1) on a common aerospace material, Inconel 718, it was shown that the material in the aged state exhibits a strength differential effect (SDE), whereby the uniaxial compressive yield and subsequent flow behavior are significantly higher than those in uniaxial tension. Thus, this material cannot be described by a standard von Mises yield formulation. There have been other formulations postulated (ref. 2) that involve other combinations of the stress invariants, including the effect of hydrostatic stress. The question remained as to which invariants are necessary in the flow model. To capture the physical mechanisms occurring during deformation and reflect them in the plasticity formulation, researchers examined the flow of Inconel 718 under various amounts of hydrostatic stress to determine whether or not hydrostatic stress is needed in the formulation. Under NASA Grant NCC3-464, monitored by the NASA Glenn Research Center, a series of tensile tests were conducted at Case Western Reserve University on aged (precipitation hardened) Inconel 718 at 650 C and with superimposed hydrostatic pressure. Dogbone shaped tensile specimens (3-mm-diameter gauge by 16-mm gauge length) and cylindrical compression specimens (3-mm-diameter gauge by 6-mm gauge length) were strain gauged and loaded in a high-pressure testing apparatus. Hydrostatic pressures were obtained with argon and ranged from 210 to 630 MPa. The aged Inconel 718 showed a pronounced difference in the tension and compression yield strength (i.e., an SDE), as previously observed. Also, there were no significant effects of hydrostatic pressure on either the tensile and compressive yield strength (see the graph) or on the magnitude of the SDE. This behavior is not consistent with the pressure-dependent theory of the SDE, which postulates that the SDE is associated with pressure-dependent and/or internal friction dependent deformation associated with non-Schmid effects at the crystal level (refs. 3 and 4). Flow in Inconel 718 appears to be independent of hydrostatic pressure, suggesting that this invariant may be removed from the phenomenological constitutive model. As part of an ongoing effort to develop advanced constitutive models, Glenn s Life Prediction Branch coordinated this work with that of research on the multiaxial deformation behavior of Inconel 718 being conducted at Pennsylvania State University under NASA Grant NCC597.

Stable isotope time series and dentin increments elucidate Pleistocene proboscidean paleobiology

NASA Astrophysics Data System (ADS)

Fisher, Daniel; Rountrey, Adam; Smith, Kathlyn; Fox, David

2010-05-01

Investigations of stable isotope composition of mineralized tissues have added greatly to our knowledge of past climates and dietary behaviors of organisms, even when they are implemented through 'bulk sampling', in which a single assay yields a single, time-averaged value. Likewise, the practice of 'sclerochronology', which documents periodic structural increments comprising a growth record for accretionary tissues, offers insights into rates of growth and age data at a scale of temporal resolution permitted by the nature of structural increments. We combine both of these approaches to analyze dental tissues of late Pleistocene proboscideans. Tusk dentin typically preserves a record of accretionary growth consisting of histologically distinct increments on daily, approximately weekly, and yearly time scales. Working on polished transverse or longitudinal sections, we mill out a succession of temporally controlled dentin samples bounded by clear structural increments with a known position in the sequence of tusk growth. We further subject each sample (or an aliquot thereof) to multiple compositional analyses - most frequently to assess δ18O and δ13C of hydroxyapatite carbonate, and δ13C and δ15N of collagen. This yields, for each animal and each series of years investigated, a set of parallel compositional time series with a temporal resolution of 1-2 months (or finer if we need additional precision). Patterns in variation of thickness of periodic sub-annual increments yield insight into intra-annual and inter-annual variation of tusk growth rate. This is informative even by itself, but it is still more valuable when coupled with compositional time series. Further, the controls on different stable isotope systems are sufficiently different that the data ensemble yields 'much more than the sum of its parts.' By assessing how compositions and growth rates covary, we monitor with greater confidence changes in local climate, diet, behavior, and health status. We illustrate the potential of this approach with case studies that reveal: season of birth and age of weaning in juvenile mammoths; age of maturation in male mastodons; season of musth in mammoths and mastodons; and season of death and tests of simultaneity of death in mammoths and mastodons. The data provided by histological and stable isotope analyses rarely reveal cause of death directly, but they can, in concert with other observations, affect perceptions of the likelihood of competing interpretations of cause of death. Most important, paleobiological inferences based on these studies can be integrated over broad geographic and temporal scales to show how specific paleobiological traits changed through time, prior to extinction. These studies have great power for investigating causes of extinction because contrasting patterns of change are expected under different hypothesized drivers of extinction.

Ground water resources of the Bryce Canyon National Park Area, Utah: With a section on the drilling of a test well

USGS Publications Warehouse

Marine, I. Wendell

1963-01-01

The water need at Bryce Canyon National Park in 1957 was about 1.3 million cubic feet for a tourist season that lasted from the middle of May to the middle of October. To evaluate the adequacy of water-supply sources, a hypothetical future need of 5 million cubic feet of water per season is used. This amount of water might be obtained from the East Fork of the Sevier River, from wells in the alluvium of the East Fork, from Yellow Creek Spring and nearby springs, which are below the canyon rim, or from a well drilled about 2,000 feet to the top of the Tropic shale. Although the present source of water, consisting of wells in the alluvium of East Creek valley, may be an important supplemental source in the future, it will not yield sufficient water in dry years to meet the total demand for water at the park.The yield of Yellow Creek Spring and nearby springs is estimated at a total of 7.8 million cubic feet of water per season. The springs provide water of satisfactory chemical quality, and are a reliable source even in times of drought. A serious disadvantage of using this source of water is the difficulty of constructing a pipeline over extremely rugged terrain from the source to the lodge and headquarters area.A well drilled to the top of the Tropic shale of Cretaceous age in the lodge and headquarters area might penetrate two or more aquifers, one at the base of the Wasatch formation of Eocene age and one or more in the Wahweap and Straight Cliffs sandstones of Cretaceous age. The yield of this well would depend to a large degree on the number of fractures encountered. To assure the most favorable conditions for intercepting fracture zones in the bedrock, a test-well site is proposed near the crest of a gentle anticline where tension fractures in the rocks should be common.Shallow wells in the alluvium of East Creek valley cannot be depended upon to yield sufficient water in times of drought, but they are nevertheless an important source. The water-storage capacity of the alluvium of East Creek valley in the vicinity of the wells of the Utah Parks Co. is estimated at 1.4 million cubic feet. By lowering the water table in the valley uniformly without creating excessively large cones of depression, the alluvium could supply the 1.3 million cubic feet of water per season estimated as the water need in 1957. However, in times of drought this alluvium cannot supply the hypothetical future needs of 5 million cubic feet of water per season.

Elevated Genetic Diversity in an F2:6 Population of Quinoa (Chenopodium quinoa) Developed through an Inter-ecotype Cross

PubMed Central

Benlhabib, Ouafae; Boujartani, Noura; Maughan, Peter J.; Jacobsen, Sven E.; Jellen, Eric N.

2016-01-01

Quinoa (Chenopodium quinoa) is a seed crop of the Andean highlands and Araucanian coastal regions of South America that has recently expanded in use and production beyond its native range. This is largely due to its superb nutritional value, consisting of protein that is rich in essential amino acids along with vitamins and minerals. Quinoa also presents a remarkable degree of tolerance to saline conditions, drought, and frost. The present study involved 72 F2:6 recombinant-inbred lines and parents developed through hybridization between highland (0654) and coastal (NL-6) germplasm groups. The purpose was to characterize the quinoa germplasm developed, to assess the discriminating potential of 21 agro-morpho-phenological traits, and to evaluate the extent of genetic variability recovered through selfing. A vast amount of genetic variation was detected among the 72 lines evaluated for quantitative and qualitative traits. Impressive transgressive segregation was measured for seed yield (22.42 g/plant), while plant height and maturity had higher heritabilities (73 and 89%, respectively). Other notable characters segregating in the population included panicle and stem color, panicle form, and resistance to downy mildew. In the Principal Component analysis, the first axis explained 74% of the total variation and was correlated to plant height, panicle size, stem diameter, biomass, mildew reaction, maturation, and seed yield; those traits are relevant discriminatory characters. Yield correlated positively with panicle length and biomass. Unweighted Pair Group Method with Arithmetic Mean-based cluster analysis identified three groups: one consisting of late, mildew-resistant, high-yielding lines; one having semi-late lines with intermediate yield and mildew susceptibility; and a third cluster consisting of early to semi-late accessions with low yield and mildew susceptibility. This study highlighted the extended diversity regenerated among the 72 accessions and helped to identify potentially adapted quinoa genotypes for production in the Moroccan coastal environment. PMID:27582753

The Effect of Aging on the Microstructure of Selective Laser Melted Cu-Ni-Si

NASA Astrophysics Data System (ADS)

Ventura, Anthony P.; Marvel, Christopher J.; Pawlikowski, Gregory; Bayes, Martin; Watanabe, Masashi; Vinci, Richard P.; Misiolek, Wojciech Z.

2017-12-01

Precipitation hardening copper alloy C70250 was selectively laser melted to successfully produce components around 98 pct dense with high mechanical strength and electrical conductivity. Aging heat treatments were carried out at 723 K (450 °C) directly on as-printed samples up to 128 hours. Mechanical testing found that peak yield strength of around 590 MPa could be attained with an electrical conductivity of 34.2 pct IACS after 8 hours of aging. Conductivity continues to increase with further aging while the peak strength appears to be less sensitive to aging time exhibiting a broad range of time where near-peak properties exist. After aging for 128 hours, there is a drop in yield strength to 546 MPa with an increase in conductivity to 43.2 pct IACS. Electron microscopy analysis revealed nanometer-scale silicon-rich oxide particles throughout the material that persist during aging. Deformation twinning is observed in the peak-age condition after tensile testing and several strengthening mechanisms appear to be active to varying degrees throughout aging which account for the broad range of aging time where nearly the peak mechanical properties exist.

Psychometric properties of the Wender-Reimherr Adult Attention Deficit Disorder Scale.

PubMed

Marchant, Barrie K; Reimherr, Fred W; Robison, Diane; Robison, Reid J; Wender, Paul H

2013-09-01

The Wender-Reimherr adult attention deficit disorder scale (WRAADDS; Wender, 1995) is a clinician-rated scale based on the Utah Criteria for attention-deficit/hyperactivity disorder (ADHD) in adults. It assesses ADHD symptom severity across 7 domains: attention difficulties, hyperactivity/restlessness, temper, affective lability, emotional over-reactivity, disorganization, and impulsivity. The normative sample consisted of 120 males and females ages 20-49 with no personal or family history of ADHD. Patients with ADHD met Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; DSM-IV-TR; American Psychiatric Association, 2000) criteria, included males and females ages 20-60, and came from 5 clinical trials. Measures of reliability (test-retest r = .96; interrater r = .75) and internal consistency (Cronbach's alpha = 0.78) were acceptable. The WRAADDS correlated with the Conners' Adult ADHD Rating Scale (CAARS; Conners, Erhardt, & Sparrow, 1999) total scores (r = .501, p < .001). WRAADDS hyperactivity + impulsivity correlated with the CAARS hyperactivity/impulsivity (r = .601, p < .001), and WRAADDS attention + disorganization correlated with the CAARS inattention (r = .430, p < .001). Discriminate validity (adults with vs. without ADHD) was significant for all domains (p < .001). Factor analysis yielded a 2-factor solution accounting for 58% of the variance, one containing the emotional dimensions and the second containing attention and disorganization. Hyperactivity/restlessness and impulsivity were split between both factors. Changes in response to treatment for the WRAADDS and CAARS were highly correlated (p < .001). These psychometric data support continued use of the WRAADDS in adults with ADHD.

Salivary testosterone levels in men at a U.S. sex club.

PubMed

Escasa, Michelle J; Casey, Jacqueline F; Gray, Peter B

2011-10-01

Vertebrate males commonly experience elevations in testosterone levels in response to sexual stimuli, such as presentation of a novel mating partner. Some previous human studies have shown that watching erotic movies increases testosterone levels in males although studies measuring testosterone changes during actual sexual intercourse or masturbation have yielded mixed results. Small sample sizes, "unnatural" lab-based settings, and invasive techniques may help account for mixed human findings. Here, we investigated salivary testosterone levels in men watching (n = 26) versus participating (n = 18) in sexual activity at a large U.S. sex club. The present study entailed minimally invasive sample collection (measuring testosterone in saliva), a naturalistic setting, and a larger number of subjects than previous work to test three hypotheses related to men's testosterone responses to sexual stimuli. Subjects averaged 40 years of age and participated between 11:00 pm and 2:10 am. Consistent with expectations, results revealed that testosterone levels increased 36% among men during a visit to the sex club, with the magnitude of testosterone change significantly greater among participants (72%) compared with observers (11%). Contrary to expectation, men's testosterone changes were unrelated to their age. These findings were generally consistent with vertebrate studies indicating elevated male testosterone in response to sexual stimuli, but also point out the importance of study context since participation in sexual behavior had a stronger effect on testosterone increases in this study but unlike some previous human lab-based studies.

A Shortened Version of the Reasons for Living-Older Adults Scale for Clinical and Research Utility.

PubMed

Lutz, Julie; Edelstein, Barry; Katz, Emma; Gallegos, Jarred V

2018-02-26

Older adults have elevated suicide rates, and identification of protective factors, such as reasons for living, is important in preventing suicide. The Reasons for Living-Older Adults scale (RFL-OA) is a 69-item measure of these protective factors in late life, which yields good psychometric properties. However, its length limits its utility in some clinical and research contexts where a shorter measure is ideal. The objective of this study was to create a shortened version of the RFL-OA. First, data collected previously during validation of the original RFL-OA (n = 199, age 65 and older, 65% female) were used to select 30 items, spanning all content areas, that were highly endorsed. Second, new data were collected (n = 219, age 60 and older, 52% female) with the 30-item RFL-OA and measures of depression, hopelessness, suicidal ideation, religiosity, health, and social desirability to examine the measure's internal consistency and convergent and discriminant validity. Scores on the 30-item RFL-OA exhibited strong internal consistency. The short RFL-OA demonstrated good convergent validity via significant, moderate correlations with suicidal ideation, hopelessness, depression, and religiosity. It demonstrated adequate discriminant validity via only small correlations with disability, subjective health, and social desirability. The shorter RFL-OA has good psychometric properties among community-dwelling older adults. It may have greater utility, compared to the original 69-item measure, for clinicians and researchers with limited time but who want to assess protective factors against suicidal behavior in late life.