Coordinated Oxygen Isotopic and Petrologic Studies of CAIS Record Varying Composition of Protosolar

NASA Technical Reports Server (NTRS)

Simon, Justin I.; Matzel, J. E. P.; Simon, S. B.; Weber, P. K.; Grossman, L.; Ross, D. K.; Hutcheon, I. D.

2012-01-01

Ca-, Al-rich inclusions (CAIs) record the O-isotope composition of Solar nebular gas from which they grew [1]. High spatial resolution O-isotope measurements afforded by ion microprobe analysis across the rims and margin of CAIs reveal systematic variations in (Delta)O-17 and suggest formation from a diversity of nebular environments [2-4]. This heterogeneity has been explained by isotopic mixing between the O-16-rich Solar reservoir [6] and a second O-16-poor reservoir (probably nebular gas) with a "planetary-like" isotopic composition [e.g., 1, 6-7], but the mechanism and location(s) where these events occur within the protoplanetary disk remain uncertain. The orientation of large and systematic variations in (Delta)O-17 reported by [3] for a compact Type A CAI from the Efremovka reduced CV3 chondrite differs dramatically from reports by [4] of a similar CAI, A37 from the Allende oxidized CV3 chondrite. Both studies conclude that CAIs were exposed to distinct, nebular O-isotope reservoirs, implying the transfer of CAIs among different settings within the protoplanetary disk [4]. To test this hypothesis further and the extent of intra-CAI O-isotopic variation, a pristine compact Type A CAI, Ef-1 from Efremovka, and a Type B2 CAI, TS4 from Allende were studied. Our new results are equally intriguing because, collectively, O-isotopic zoning patterns in the CAIs indicate a progressive and cyclic record. The results imply that CAIs were commonly exposed to multiple environments of distinct gas during their formation. Numerical models help constrain conditions and duration of these events.

Clumped Isotope Composition of Cold-Water Corals: A Role for Vital Effects?

NASA Astrophysics Data System (ADS)

Spooner, P.; Guo, W.; Robinson, L. F.

2014-12-01

Measurements on a set of cold-water corals (mainly Desmophyllum dianthus) have suggested that their clumped isotope composition could serve as a promising proxy for reconstructing paleocean temperatures. Such measurements have also offered support for certain isotope models of coral calcification. However, there are differences in the clumped isotope compositions between warm-water and cold-water corals, suggesting that different kinds of corals could have differences in their biocalcification processes. In order to understand the systematics of clumped isotope variations in cold-water corals more fully, we present clumped isotope data from a range of cold-water coral species from the tropical Atlantic and the Southern Ocean.Our samples were either collected live or recently dead (14C ages < 1,000 yrs) with associated temperature data. They include a total of 11 solitary corals and 1 colonial coral from the Atlantic, and 8 solitary corals from the Southern Ocean. The data indicate that coral clumped isotope systematics may be more complicated than previously thought. For example, for the genus Caryophyllia we observe significant variations in clumped isotope compositions for corals which grew at the same temperature with an apparent negative correlation between Δ47 and δ18O, different to patterns previously observed in Desmophyllum. These results indicate that existing isotope models of biocalcification may not apply equally well to all corals. Clumped isotope vital effects may be present in certain cold-water corals as they are in warm-water corals, complicating the use of this paleoclimate proxy.

Mineral and chemical variations within an ash-flow sheet from Aso caldera, Southwestern Japan

USGS Publications Warehouse

Lipman, P.W.

1967-01-01

Although products of individual volcanic eruptions, especially voluminous ash-flow eruptions, have been considered among the best available samples of natural magmas, detailed petrographic and chemical study indicates that bulk compositions of unaltered Pleistocene ash-flow tuffs from Aso caldera, Japan, deviate significantly from original magmatic compositions. The last major ash-flow sheet from Aso caldera is as much as 150 meters thick and shows a general vertical compositional change from phenocryst-poor rhyodacite upward into phenocryst-rich trachyandesite; this change apparently reflects in inverse order a compositionally zoned magma chamber in which more silicic magma overlay more mafic magma. Details of these magmatic variations were obscured, however, by: (1) mixing of compositionally distinct batches of magma during upwelling in the vent, as indicated by layering and other heterogeneities within single pumice lumps; (2) mixing of particulate fragments-pumice lumps, ash, and phenocrysts-of varied compositions during emplacement, with the result that separate pumice lenses from a single small outcrop may have a compositional range nearly as great as the bulk-rook variation of the entire sheet; (3) density sorting of phenocrysts and ash during eruption and emplacement, resulting in systematic modal variations with distance from the caldera; (4) addition of xenocrysts, resulting in significant contamination and modification of proportions of crystals in the tuffs; and (5) ground-water leaching of glassy fractions during hydration after cooling. Similar complexities characterize ash-flow tuffs under study in southwestern Nevada and in the San Juan Mountains, Colorado, and probably are widespread in other ash-flow fields as well. Caution and careful planning are required in study of the magmatic chemistry and phenocryst mineralogy of these rocks. ?? 1967 Springer-Verlag.

Re-assessing the Molybdenum Isotope Composition of Pre-GOE Seawater: Evidence for Dynamic Ocean Redox

NASA Astrophysics Data System (ADS)

Ostrander, C. M.; Kendall, B.; Roy, M.; Romaniello, S. J.; Nunn, S. J.; Gordon, G. W.; Olson, S. L.; Lyons, T. W.; Zheng, W.; Anbar, A. D.

2016-12-01

Molybdenum (Mo) isotope compositions of Archean shales can provide important insights into ocean and atmosphere redox dynamics prior to the Great Oxidation Event (GOE). Unfortunately, the relatively limited Mo isotope database and small number of sample sets for Archean shales do not allow for in-depth reconstructions and specifically make it difficult to differentiate global from local effects. To accurately estimate the Mo isotope composition of Archean seawater and better investigate the systematics of local and global redox, more complete sample sets are needed. We carried out a Mo isotope analysis of the euxinic 2.65 Ga Roy Hill Shale sampled in two stratigraphically correlated cores, and revisited the well-studied euxinic 2.5 Ga Mt. McRae Shale in higher resolution. Our data show contrasting Mo isotope values in the 2.65 Ga Roy Hill Shale between near- and offshore depositional environments, with systematically heavier isotope values in the near-shore environment. High-resolution analysis of the Mt. McRae Shale yields oscillating Mo concentrations and isotope values at the cm- to dm-scale during the well-characterized "whiff of O2" interval, with the heaviest isotope values measured during euxinic deposition. Variations in the measured isotope values within each section are primarily associated with redox changes in the local depositional environment and amount of detrital content. Both non-quantitative removal of Mo associated with incorporation into non-euxinic sediments and large detrital Mo contributions shift some measured isotopic compositions toward lighter values. This is readily apparent in the near-shore Roy Hill Shale section and the Mt. McRae Shale, but may not fully explain variations observed in the offshore Roy Hill Shale deposit. Here, euxinic deposition is not accompanied by Mo enrichments or isotopic compositions as heavy as the near-shore equivalent, even after detrital correction. This disparity between the near- and offshore environment could signify spatial variation in the Mo isotope composition of 2.65 Ga seawater and highlights the need for multi-site and high-resolution studies in order to best assess paleoenvironmental conditions.

Chemical Evidence for Vertical Transport from Magma Chambers to the Surface During Mid-Ocean Ridge Volcanic Eruptions

NASA Astrophysics Data System (ADS)

Sinton, J. M.; Rubin, K. H.

2009-12-01

Many mid-ocean ridge eruptions show significant internal chemical heterogeneity; in general, the amount of chemical heterogeneity within eruptions scales with erupted volume. These variations reflect magmatic processes occurring in magma reservoirs prior to or possibly during eruption. For example, systematic variations in Mg# with along-axis distance in the early 90’s Aldo-Kihi (S. EPR near 17.5°S), 1996 N. Gorda, 1993 Co-Axial (Juan de Fuca Ridge), and 1991-2 and 2005-6 9°50’N EPR eruptions is unlikely to be related to fractionation during emplacement, and rather reflects variations in sub-axial magma reservoirs prior to eruption. Such variations are inconsistent with well-mixed sub-axial reservoirs and, in some cases, require relatively long-lived, systematic variations in reservoir temperatures along axis. Chemical heterogeneity within the Aldo-Kihi eruption preserves spatial variations in mantle-derived isotopic and trace element ratios with implications for the temporal and spatial scales of magma injections to the crust and along-axis mixing within shallow reservoirs. These spatial variations are difficult to reconcile with significant (> ~1 km) along-axis magma transport, as are striking correlations of chemical compositions with surface geological discontinuities or seismically imaged sub-axial magma chamber reflectors in the S. Hump (S. EPR), 9°50’N EPR, N. Gorda and 1975-1984 Krafla (N. Iceland) eruptive units. Rather, spatial correlations between surface lava compositions and sub-axial magma chamber properties or long-lived axial morphology suggest that most of the erupted magma was transported nearly vertically from the underlying reservoirs to the surface during these eruptions. In the case of the Krafla eruption, coincident deformation suggests a component of lateral melt migration at depth, despite chemical evidence for vertical transport of erupted lava from more than one chemical reservoir. In addition, along-ridge movement of earthquake epicenters during the 1992 Co-Axial and 1996 Gorda eruptions implies migration of stress release during these eruptions, even though vertical transport better explains chemical patterns. The nature of transport for most eruptions is unclear because of lack of systematic chemical patterns; this presentation emphasizes those cases where vertical transport appears to be required.

Tracing subducted crustal materials in the mantle by using magnesium isotopes

NASA Astrophysics Data System (ADS)

Teng, F. Z.

2016-12-01

Recent studies show that some continental basalt, mantle-metasomatised peridotite and cratonic eclogite have heterogeneous Mg isotopic compositions. These isotopically distinct Mg isotopic compositions have been explained by the incorporation of subducted materials in their mantle sources though the detailed mechanisms are still not well understood. In particular, how Mg-poor crustal materials can modify Mg isotopic systematics of Mg-rich mantle is unknown. Subduction zones are the most efficient sites for crust and mantle interactions, hence should be where the most prominent Mg isotopic variation occurs. However, to date, little is known on Mg isotope systematics in the subduction factory. Here I first review and report new Mg isotopic data for arc lava, subarc peridotite and the subducted slab (marine sediment, altered basalt and abyssal peridotite), then use them to constrain the origins of mantle Mg isotopic heterogeneity and lay the foundation for using Mg isotopes as new tools for tracing crust-mantle interactions. The main conclusions are 1) fluid-rock interactions can modify Mg isotopic systematics of abyssal peridotites; 2) island arc lavas have non-MORB Mg isotopic compositions, reflecting distinct surbarc mantle Mg isotopic signature; 3) continental arcs have non-MORB Mg isotopic compositions, likely resulting from crustal contamination and 4) the isotopically heterogeneous continental basalts are mainly produced by mixing of isotopically distinct magmas instead of being partial melting products of metasomatised mantle peridotites.

Similar Processes but Different Environmental Filters for Soil Bacterial and Fungal Community Composition Turnover on a Broad Spatial Scale

PubMed Central

Chemidlin Prévost-Bouré, Nicolas; Dequiedt, Samuel; Thioulouse, Jean; Lelièvre, Mélanie; Saby, Nicolas P. A.; Jolivet, Claudy; Arrouays, Dominique; Plassart, Pierre; Lemanceau, Philippe; Ranjard, Lionel

2014-01-01

Spatial scaling of microorganisms has been demonstrated over the last decade. However, the processes and environmental filters shaping soil microbial community structure on a broad spatial scale still need to be refined and ranked. Here, we compared bacterial and fungal community composition turnovers through a biogeographical approach on the same soil sampling design at a broad spatial scale (area range: 13300 to 31000 km2): i) to examine their spatial structuring; ii) to investigate the relative importance of environmental selection and spatial autocorrelation in determining their community composition turnover; and iii) to identify and rank the relevant environmental filters and scales involved in their spatial variations. Molecular fingerprinting of soil bacterial and fungal communities was performed on 413 soils from four French regions of contrasting environmental heterogeneity (Landes

Similar processes but different environmental filters for soil bacterial and fungal community composition turnover on a broad spatial scale.

PubMed

Chemidlin Prévost-Bouré, Nicolas; Dequiedt, Samuel; Thioulouse, Jean; Lelièvre, Mélanie; Saby, Nicolas P A; Jolivet, Claudy; Arrouays, Dominique; Plassart, Pierre; Lemanceau, Philippe; Ranjard, Lionel

2014-01-01

Spatial scaling of microorganisms has been demonstrated over the last decade. However, the processes and environmental filters shaping soil microbial community structure on a broad spatial scale still need to be refined and ranked. Here, we compared bacterial and fungal community composition turnovers through a biogeographical approach on the same soil sampling design at a broad spatial scale (area range: 13300 to 31000 km2): i) to examine their spatial structuring; ii) to investigate the relative importance of environmental selection and spatial autocorrelation in determining their community composition turnover; and iii) to identify and rank the relevant environmental filters and scales involved in their spatial variations. Molecular fingerprinting of soil bacterial and fungal communities was performed on 413 soils from four French regions of contrasting environmental heterogeneity (Landes

Actualistic models of mantle metasomatism documented in a composite xenolith from Dish Hill, California

USGS Publications Warehouse

Nielson, J.E.; Budahn, J.R.; Unruh, D.M.; Wilshire, H.G.

1993-01-01

Major and trace-element whole rock and mineral variations in composite hornblendite-peridotite xenolith Ba-2-1, from Dish Hill, CA, are due to a single event of metasomatism in the mantle. The hornblendite is the crystallized selvage of a dike conduit charged with incompatible-element-enriched hydrous mafic magma. The magma infiltrated the refractory peridotite wallrock, reacted with its constituent minerals, and simultaneously deposited amphibole. The systematic data from this study show considerable variation in isotopic values and trace elements. These data provide insight into a mantle process that was defined previously from samples without context, lacking evidence about the number or source of metasomatic events. In the contact zone of Ba-2-1, peridotite is enriched in Fe, Ti, CO2) and H2O; clinopyroxene and amphibole also are enriched in Fe and Ti, but clinopyroxene appears slightly depleted in CaO. Compared to chondrites, peridotite, clinopyroxene, and probably amphibole are enriched in light rare earth (LREEcn) and other incompatible trace elements. Values of 87Sr 86Sr and 143Nd 144Nd in the contact zone are close to isotopic equilibrium with the dike. Whole rock and constituent clinopyroxene compositions change to those of refractory peridotite with distance from the contact. These compositional variations were modelled using Gresens' equation for whole-rock major and minor elements, and calculations for isotopic ratios and REEs, which emulate the effects of Chromatographic fractionation. The choice of endmembers was restricted to compositions actually present in mantle samples from Dish Hill. Model results indicate that: 1. (1) the variations can be explained as the result of a single metasomatic event, probably a single pulse of previously fractionated liquid; 2. (2) the ratio of total interacting liquid to peridotite was at least 1:3 by weight in the contact zone; and 3. (3) the composition of the metasomatic liquid changed progressively as it infiltrated beyond that zone. The small distance over which variations occur is due to the small amount of liquid that infiltrated. Only in the contact zone was peridotite wallrock saturated by a liquid composition similar to the dike. Comparison of the Ba-2-1 data with those of another xenolith from Dish Hill suggests that the compositional variations of mantle metasomatism result from both the compositional contrast between the metasomatizing liquid and wallrock and the relative abundances of each. Compositional and volumetric variations of mantle partial melts and their fractionates, and repeated events of melting and reaction in contiguous mantle, can create broad ranges of metasomatic "signatures" from the same process. ?? 1993.

Synthesis and ferroelectric properties of La-substituted PZFNT

NASA Astrophysics Data System (ADS)

Singh, Pratibha; Singh, Sangeeta; Juneja, J. K.; Prakash, Chandra; Raina, K. K.; Kumar, Vinod; Pant, R. P.

2010-01-01

In this paper we are reporting a systematic study on ferroelectric properties of lanthanum (La) substituted modified lead zirconate titanate (PLZFNT) ceramics which were fabricated by mixed oxide process. La contents were varied in between 0 and 0.01 in steps of 0.0025. The X-ray diffraction study shows single phase for all samples. Silver electrode was deposited on flat surfaces of sintered discs for P-E (polarization vs. electric field) measurements. All compositions exhibited well-defined ferroelectric behavior at room temperature. Hysteresis loops were also recorded at different temperatures for all the compositions which showed typical variation of ferroelectric nature. The PLZFNT composition with 1 mol% of La showed the best retention behavior. The results are discussed.

Compositional and mineralogical zoning by inward crystallization of mafic magma: evidence from the Guwoon hornblende gabbro-diorite Complex, Hwacheon, Korea.

NASA Astrophysics Data System (ADS)

Park, Y.-R.; Kim, G.-Y.

2009-04-01

The small body, ca. 1.3 by 1.6km, of a hot-air ballon shape hornblende gabbro - diorite Complex, in Gowoonri, Hwacheon, Korea consists of marginal diorite and central hornblende gabbro. The volumetrically dominant hornblende gabbro in the core of the Complex shows a zoned distribution with three layers distinguished by different dominant mafic mineral phases. From the margin toward the core of the hornblende gabbro body, the domintant mafic minerals change from amphibole phenocryst of nearly rounded shape in cross section with pyroxene pseudomorph through prismatic shape of amphibole to polycrystalline biotite aggregates. Systematic variations in geochemical characteristics among three distinct zones of hornblende gabbro body are also observed. From the outer zone toward the core, major oxides such as MnO, MgO, and CaO show a decreasing tendency, whereas total FeO/(total FeO + MgO) value shows an increasing tendency. Concentrations of trace elements also show systematic variations. Where incompatible elements such as Ba and Th increase, compatible elements like Cr and Sc decrease from the margin toward the core. The zonal distribution divided by change in dominant mafic mineral phase from pyroxene through amphibole to biotite, and systematic compositional changes in both major and trace elements from the outer zone toward the core of the hornblende gabbro body suggest that an inward crystallization mechanism played a major role in the formation of the hornblende gabbro in Guwoonri, Hwacheon, Korea.

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

Hattrick-Simpers, Jason R.; Gregoire, John M.; Kusne, A. Gilad

With their ability to rapidly elucidate composition-structure-property relationships, high-throughput experimental studies have revolutionized how materials are discovered, optimized, and commercialized. It is now possible to synthesize and characterize high-throughput libraries that systematically address thousands of individual cuts of fabrication parameter space. An unresolved issue remains transforming structural characterization data into phase mappings. This difficulty is related to the complex information present in diffraction and spectroscopic data and its variation with composition and processing. Here, we review the field of automated phase diagram attribution and discuss the impact that emerging computational approaches will have in the generation of phase diagrams andmore » beyond.« less

Alkali elemental and potassium isotopic compositions of Semarkona chondrules

USGS Publications Warehouse

Alexander, C.M. O'D.; Grossman, J.N.

2005-01-01

We report measurements of K isotope ratios in 28 Semarkona chondrules with a wide range of petrologic types and bulk compositions as well as the compositions of CPX-mesostasis pairs in 17 type I Semarkona chondrules, including two chondrules with radial alkali zonation and 19 type II chondrules. Despite the wide range in K/Al ratios, no systematic variations in K isotopic compositions were found. Semarkona chondrules do not record a simple history of Rayleigh-type loss of K. Experimentally determined evaporation rates suggest that considerable alkali evaporation would have occurred during chondrule formation. Nevertheless, based on Na CPX-mesostasis distribution coefficients, the alkali contents of the cores of most chondrules in Semarkona were probably established at the time of final crystallization. However, Na CPX-mesostasis distribution coefficients also show that alkali zonation in type I Semarkona chondrules was produced by entry of alkalis after solidification, probably during parent body alteration. This alkali metasomatism may have gone to completion in some chondrules. Our preferred explanation for the lack of systematic isotopic enrichments, even in alkali depleted type I chondrule cores, is that they exchanged with the ambient gas as they cooled. ?? The Meteoritical Society, 2005.

An Exploration of the Importance of Flood Heterogeneity for Regionalization in Arizona using the Expected Moments Algorithm

NASA Astrophysics Data System (ADS)

Zamora-Reyes, D.; Hirschboeck, K. K.; Paretti, N. V.

2012-12-01

Bulletin 17B (B17B) has prevailed for 30 years as the standard manual for determining flood frequency in the United States. Recently proposed updates to B17B include revising the issue of flood heterogeneity, and improving flood estimates by using the Expected Moments Algorithm (EMA) which can better address low outliers and accommodate information on historical peaks. Incorporating information on mixed populations, such as flood-causing mechanisms, into flood estimates for regions that have noticeable flood heterogeneity can be statistically challenging when systematic flood records are short. The problem magnifies when the population sample size is reduced by decomposing the record, especially if multiple flood mechanisms are involved. In B17B, the guidelines for dealing with mixed populations focus primarily on how to rule out any need to perform a mixed-population analysis. However, in some regions mixed flood populations are critically important determinants of regional flood frequency variations and should be explored from this perspective. Arizona is an area with a heterogeneous mixture of flood processes due to: warm season convective thunderstorms, cool season synoptic-scale storms, and tropical cyclone-enhanced convective activity occurring in the late summer or early fall. USGS station data throughout Arizona was compiled into a database and each flood peak (annual and partial duration series) was classified according to its meteorological cause. Using these data, we have explored the role of flood heterogeneity in Arizona flood estimates through composite flood frequency analysis based on mixed flood populations using EMA. First, for selected stations, the three flood-causing populations were separated out from the systematic annual flood series record and analyzed individually. Second, to create composite probability curves, the individual curves for each of the three populations were generated and combined using Crippen's (1978) composite probability equations for sites that have two or more independent flood populations. Finally, the individual probability curves generated for each of the three flood-causing populations were compared with both the site's composite probability curve and the standard B17B curve to explore the influence of heterogeneity using the 100-year and 200-year flood estimates as a basis of comparison. Results showed that sites located in southern Arizona and along the abrupt elevation transition zone of the Mogollon Rim exhibit a better fit to the systematic data using their composite probability curves than the curves derived from standard B17B analysis. Synoptic storm floods and tropical cyclone-enhanced floods had the greatest influence on 100-year and 200-year flood estimates. This was especially true in southern Arizona, even though summer convective floods are much more frequent and therefore dominate the composite curve. Using the EMA approach also influenced our results because all possible low outliers were censored by the built-in Multiple Grubbs-Beck Test, providing a better fit to the systematic data in the upper probabilities. In conclusion, flood heterogeneity can play an important role in regional flood frequency variations in Arizona and that understanding its influence is important when making projections about future flood variations.

Evaluation of the efficacy of flowable composite as lining material on microleakage of composite resin restorations: A systematic review and meta-analysis.

PubMed

Boruziniat, Alireza; Gharaee, Samineh; Sarraf Shirazi, Alireza; Majidinia, Sara; Vatanpour, Mehdi

2016-02-01

The efficacy of flowable composite in improving marginal adaptation or reducing microleakage is not fully understood. The purpose of this study was to systematically evaluate existing evidence to verify whether an application of flowable composite as a liner provided less microleakage in Class 2 composite restorations. PubMed, ISI (Web of Science), and Scopus databases were searched according to the selected keywords, up to 15 Feb 2015, without any restriction on date or language. Full texts of published articles that seemed to meet primary criteria for inclusion in this research were obtained. Data of studies were extracted if they were assessed as high or moderate level of evidence. Due to the variation of methods used in different studies, they were divided into five groups: groups 1 and 2, studies that evaluated the effect of flowable composite as a liner on dentinal or enamel margins and applied flowable composite on all of the cavity wall margins; groups 3 and 4, studies that evaluated the effect of flowable composite as a liner on dentinal and enamel margins and applied flowable composite only on gingival margin; and group 5, clinical studies. The initial search yielded 1,370 publications. After hand searching, six extra studies were included in the review. The abstracts of all were read independently by AB and SG. After methodologic assessment and evaluation of the level of evidence, 18 studies were selected for this study. The results of this study indicate that flowable composite liners have no significant effect on microleakage of composite restorations in all of five groups. Application of flowable composite as a liner in composite restorations cannot reduce microleakage or improve clinical performance.

Body composition in elderly people: effect of criterion estimates on predictive equations

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

Baumgartner, R.N.; Heymsfield, S.B.; Lichtman, S.

1991-06-01

The purposes of this study were to determine whether there are significant differences between two- and four-compartment model estimates of body composition, whether these differences are associated with aqueous and mineral fractions of the fat-free mass (FFM); and whether the differences are retained in equations for predicting body composition from anthropometry and bioelectric resistance. Body composition was estimated in 98 men and women aged 65-94 y by using a four-compartment model based on hydrodensitometry, {sup 3}H{sub 2}O dilution, and dual-photon absorptiometry. These estimates were significantly different from those obtained by using Siri's two-compartment model. The differences were associated significantly (Pmore » less than 0.0001) with variation in the aqueous fraction of FFM. Equations for predicting body composition from anthropometry and resistance, when calibrated against two-compartment model estimates, retained these systematic errors. Equations predicting body composition in elderly people should be calibrated against estimates from multicompartment models that consider variability in FFM composition.« less

Application of Positron Doppler Broadening Spectroscopy to the Measurement of the Uniformity of Composite Materials

NASA Astrophysics Data System (ADS)

Quarles, C. A.; Sheffield, Thomas; Stacy, Scott; Yang, Chun

2009-03-01

The uniformity of rubber-carbon black composite materials has been investigated with positron Doppler Broadening Spectroscopy (DBS). The number of grams of carbon black (CB) mixed into one hundred grams of rubber, phr, is used to characterize a sample. A typical concentration for rubber in tires is 50 phr. The S parameter measured by DBS has been found to depend on the phr of the sample as well as the type of rubber and carbon black. The variation in carbon black concentration within a surface area of about 5 mm diameter can be measured by moving a standard Na-22 or Ge-68 positron source over an extended sample. The precision of the concentration measurement depends on the dwell time at a point on the sample. The time required to determine uniformity over an extended sample can be reduced by running with much higher counting rate than is typical in DBS and correcting for the systematic variation of S parameter with counting rate. Variation in CB concentration with mixing time at the level of about 0.5% has been observed.

Tactical Defenses Against Systematic Variation in Wind Tunnel Testing

NASA Technical Reports Server (NTRS)

DeLoach, Richard

2002-01-01

This paper examines the role of unexplained systematic variation on the reproducibility of wind tunnel test results. Sample means and variances estimated in the presence of systematic variations are shown to be susceptible to bias errors that are generally non-reproducible functions of those variations. Unless certain precautions are taken to defend against the effects of systematic variation, it is shown that experimental results can be difficult to duplicate and of dubious value for predicting system response with the highest precision or accuracy that could otherwise be achieved. Results are reported from an experiment designed to estimate how frequently systematic variations are in play in a representative wind tunnel experiment. These results suggest that significant systematic variation occurs frequently enough to cast doubts on the common assumption that sample observations can be reliably assumed to be independent. The consequences of ignoring correlation among observations induced by systematic variation are considered in some detail. Experimental tactics are described that defend against systematic variation. The effectiveness of these tactics is illustrated through computational experiments and real wind tunnel experimental results. Some tutorial information describes how to analyze experimental results that have been obtained using such quality assurance tactics.

Evaluating potential overlap between pack stock and Sierra Nevada bighorn sheep (Ovis canadensis sierrae) in Sequoia and Kings Canyon National Parks, California

USGS Publications Warehouse

Klinger, Robert C.; Few, Alexandra P.; Knox, Kathleen A.; Hatfield, Brian E.; Clark, Jonathan; German, David W.; Stephenson, Thomas R.

2015-01-01

The association analyses indicated the potential for overlap between pack stock and SNBS was minimal; only 1 percent of the potential meadow area in the SNBS herd home ranges overlapped that of pack stock meadows. There were no systematic differences in overall vegetation structure or composition, or in diversity, cover, or composition of forage species, that indicated pack stock were altering SNBS habitat or affecting their nutrition. Variation in plant species composition was influenced primarily by random differences among meadows and environmental gradients, and there was little evidence that pack stock use contributed in meaningful ways to this variation. The few differences among meadows with different levels of use by bighorn sheep and pack stock either were minor or were not in a direction consistent with negative effects of pack stock on SNBS. We conclude that the current plan for managing pack stock grazing has been successful in minimizing significant negative effects on Sierra Nevada bighorn sheep at Sequoia and Kings Canyon National Parks.

Variational asymptotic modeling of composite dimensionally reducible structures

NASA Astrophysics Data System (ADS)

Yu, Wenbin

A general framework to construct accurate reduced models for composite dimensionally reducible structures (beams, plates and shells) was formulated based on two theoretical foundations: decomposition of the rotation tensor and the variational asymptotic method. Two engineering software systems, Variational Asymptotic Beam Sectional Analysis (VABS, new version) and Variational Asymptotic Plate and Shell Analysis (VAPAS), were developed. Several restrictions found in previous work on beam modeling were removed in the present effort. A general formulation of Timoshenko-like cross-sectional analysis was developed, through which the shear center coordinates and a consistent Vlasov model can be obtained. Recovery relations are given to recover the asymptotic approximations for the three-dimensional field variables. A new version of VABS has been developed, which is a much improved program in comparison to the old one. Numerous examples are given for validation. A Reissner-like model being as asymptotically correct as possible was obtained for composite plates and shells. After formulating the three-dimensional elasticity problem in intrinsic form, the variational asymptotic method was used to systematically reduce the dimensionality of the problem by taking advantage of the smallness of the thickness. The through-the-thickness analysis is solved by a one-dimensional finite element method to provide the stiffnesses as input for the two-dimensional nonlinear plate or shell analysis as well as recovery relations to approximately express the three-dimensional results. The known fact that there exists more than one theory that is asymptotically correct to a given order is adopted to cast the refined energy into a Reissner-like form. A two-dimensional nonlinear shell theory consistent with the present modeling process was developed. The engineering computer code VAPAS was developed and inserted into DYMORE to provide an efficient and accurate analysis of composite plates and shells. Numerical results are compared with the exact solutions, and the excellent agreement proves that one can use VAPAS to analyze composite plates and shells efficiently and accurately. In conclusion, rigorous modeling approaches were developed for composite beams, plates and shells within a general framework. No such consistent and general treatment is found in the literature. The associated computer programs VABS and VAPAS are envisioned to have many applications in industry.

Near-infrared spectral reflectance of mineral mixtures - Systematic combinations of pyroxenes, olivine, and iron oxides

NASA Technical Reports Server (NTRS)

Singer, R. B.

1981-01-01

Near-infrared spectral reflectance data are presented for systematic variations in weight percent of two component mixtures of ferromagnesium and iron oxide minerals used to study the dark materials on Mars. Olivine spectral features are greatly reduced in contrast by admixture of other phases but remain distinctive even for low olivine contents. Clinopyroxene and orthopyroxene mixtures show resolved pyroxene absorptions near 2 microns. Limonite greatly modifies pyroxene and olivine reflectance, but does not fully eliminate distinctive spectral characteristics. Using only spectral data in the 1 micron region, it is difficult to differentiate orthopyroxene and limonite in a mixture. All composite mineral absorptions were either weaker than or intermediate in strength to the end-member absorptions and have bandwidths greater than or equal to those for the end members. In general, spectral properties in an intimate mixture combine in a complex, nonadditive manner, with features demonstrating a regular but usually nonlinear variation as a function of end-member phase proportions.

Oxygen isotopic composition and U-Pb discordance in zircon

USGS Publications Warehouse

Booth, A.L.; Kolodny, Y.; Chamberlain, C.P.; McWilliams, M.; Schmitt, A.K.; Wooden, J.

2005-01-01

We have investigated U-Pb discordance and oxygen isotopic composition of zircon using high-spatial resolution ??18O measurement by ion microprobe. ??18O in both concordant and discordant zircon grains provides an indication of the relationship between fluid interaction and discordance. Our results suggest that three characteristics of zircon are interrelated: (1) U-Pb systematics and concomitant age discordance, (2) ??18O and the water-rock interactions implied therein, and (3) zircon texture, as revealed by cathodoluminescence and BSE imaging. A key observation is that U-Pb-disturbed zircons are often also variably depleted in 18O, but the relationship between discordance and ??18O is not systematic. ??18O values of discordant zircons are generally lighter but irregular in their distribution. Textural differences between zircon grains can be correlated with both U-Pb discordance and ??18O. Discordant grains exhibit either a recrystallized, fractured, or strongly zoned CL texture, and are characteristic of 18O depletion. We interpret this to be a result of metamictization, leading to destruction of the zircon lattice and an increased susceptibility to lead loss. Conversely, grains that are concordant have less-expressed zoning and a smoother CL texture and are enriched in 18O. From this it is apparent that various stages of water-rock interaction, as evidenced by systematic variations in ??18O, leave their imprint on both the texture and U-Pb systematics of zircon. Copyright ?? 2005 Elsevier Ltd.

Temporal geochemical variations in lavas from Kīlauea's Pu`u `Ō`ō eruption (1983-2010): Cyclic variations from melting of source heterogeneities

NASA Astrophysics Data System (ADS)

Greene, Andrew R.; Garcia, Michael O.; Pietruszka, Aaron J.; Weis, Dominique; Marske, Jared P.; Vollinger, Michael J.; Eiler, John

2013-11-01

Geochemical time series analysis of lavas from Kīlauea's ongoing Pu`u `Ō`ō eruption chronicle mantle and crustal processes during a single, prolonged (1983 to present) magmatic event, which has shown nearly two-fold variation in lava effusion rates. Here we present an update of our ongoing monitoring of the geochemical variations of Pu`u `Ō`ō lavas for the entire eruption through 2010. Oxygen isotope measurements on Pu`u `Ō`ō lavas show a remarkable range (δ18O values of 4.6-5.6‰), which are interpreted to reflect moderate levels of oxygen isotope exchange with or crustal contamination by hydrothermally altered Kīlauea lavas, probably in the shallow reservoir under the Pu`u `Ō`ō vent. This process has not measurably affected ratios of radiogenic isotope or incompatible trace elements, which are thought to vary due to mantle-derived changes in the composition of the parental magma delivered to the volcano. High-precision Pb and Sr isotopic measurements were performed on lavas erupted at ˜6 month intervals since 1983 to provide insights about melting dynamics and the compositional structure of the Hawaiian plume. The new results show systematic variations of Pb and Sr isotope ratios that continued the long-term compositional trend for Kīlauea until ˜1990. Afterward, Pb isotope ratios show two cycles with ˜10 year periods, whereas the Sr isotope ratios continued to increase until ˜2003 and then shifted toward slightly less radiogenic values. The short-term periodicity of Pb isotope ratios may reflect melt extraction from mantle with a fine-scale pattern of repeating source heterogeneities or strands, which are about 1-3 km in diameter. Over the last 30 years, Pu`u `Ō`ō lavas show 15% and 25% of the known isotopic variation for Kīlauea and Mauna Kea, respectively. This observation illustrates that the dominant time scale of mantle-derived compositional variation for Hawaiian lavas is years to decades.

Metabolic Model-Based Integration of Microbiome Taxonomic and Metabolomic Profiles Elucidates Mechanistic Links between Ecological and Metabolic Variation.

PubMed

Noecker, Cecilia; Eng, Alexander; Srinivasan, Sujatha; Theriot, Casey M; Young, Vincent B; Jansson, Janet K; Fredricks, David N; Borenstein, Elhanan

2016-01-01

Multiple molecular assays now enable high-throughput profiling of the ecology, metabolic capacity, and activity of the human microbiome. However, to date, analyses of such multi-omic data typically focus on statistical associations, often ignoring extensive prior knowledge of the mechanisms linking these various facets of the microbiome. Here, we introduce a comprehensive framework to systematically link variation in metabolomic data with community composition by utilizing taxonomic, genomic, and metabolic information. Specifically, we integrate available and inferred genomic data, metabolic network modeling, and a method for predicting community-wide metabolite turnover to estimate the biosynthetic and degradation potential of a given community. Our framework then compares variation in predicted metabolic potential with variation in measured metabolites' abundances to evaluate whether community composition can explain observed shifts in the community metabolome, and to identify key taxa and genes contributing to the shifts. Focusing on two independent vaginal microbiome data sets, each pairing 16S community profiling with large-scale metabolomics, we demonstrate that our framework successfully recapitulates observed variation in 37% of metabolites. Well-predicted metabolite variation tends to result from disease-associated metabolism. We further identify several disease-enriched species that contribute significantly to these predictions. Interestingly, our analysis also detects metabolites for which the predicted variation negatively correlates with the measured variation, suggesting environmental control points of community metabolism. Applying this framework to gut microbiome data sets reveals similar trends, including prediction of bile acid metabolite shifts. This framework is an important first step toward a system-level multi-omic integration and an improved mechanistic understanding of the microbiome activity and dynamics in health and disease. Studies characterizing both the taxonomic composition and metabolic profile of various microbial communities are becoming increasingly common, yet new computational methods are needed to integrate and interpret these data in terms of known biological mechanisms. Here, we introduce an analytical framework to link species composition and metabolite measurements, using a simple model to predict the effects of community ecology on metabolite concentrations and evaluating whether these predictions agree with measured metabolomic profiles. We find that a surprisingly large proportion of metabolite variation in the vaginal microbiome can be predicted based on species composition (including dramatic shifts associated with disease), identify putative mechanisms underlying these predictions, and evaluate the roles of individual bacterial species and genes. Analysis of gut microbiome data using this framework recovers similar community metabolic trends. This framework lays the foundation for model-based multi-omic integrative studies, ultimately improving our understanding of microbial community metabolism.

Metabolic Model-Based Integration of Microbiome Taxonomic and Metabolomic Profiles Elucidates Mechanistic Links between Ecological and Metabolic Variation

PubMed Central

Noecker, Cecilia; Eng, Alexander; Srinivasan, Sujatha; Theriot, Casey M.; Young, Vincent B.; Jansson, Janet K.; Fredricks, David N.

2016-01-01

ABSTRACT Multiple molecular assays now enable high-throughput profiling of the ecology, metabolic capacity, and activity of the human microbiome. However, to date, analyses of such multi-omic data typically focus on statistical associations, often ignoring extensive prior knowledge of the mechanisms linking these various facets of the microbiome. Here, we introduce a comprehensive framework to systematically link variation in metabolomic data with community composition by utilizing taxonomic, genomic, and metabolic information. Specifically, we integrate available and inferred genomic data, metabolic network modeling, and a method for predicting community-wide metabolite turnover to estimate the biosynthetic and degradation potential of a given community. Our framework then compares variation in predicted metabolic potential with variation in measured metabolites’ abundances to evaluate whether community composition can explain observed shifts in the community metabolome, and to identify key taxa and genes contributing to the shifts. Focusing on two independent vaginal microbiome data sets, each pairing 16S community profiling with large-scale metabolomics, we demonstrate that our framework successfully recapitulates observed variation in 37% of metabolites. Well-predicted metabolite variation tends to result from disease-associated metabolism. We further identify several disease-enriched species that contribute significantly to these predictions. Interestingly, our analysis also detects metabolites for which the predicted variation negatively correlates with the measured variation, suggesting environmental control points of community metabolism. Applying this framework to gut microbiome data sets reveals similar trends, including prediction of bile acid metabolite shifts. This framework is an important first step toward a system-level multi-omic integration and an improved mechanistic understanding of the microbiome activity and dynamics in health and disease. IMPORTANCE Studies characterizing both the taxonomic composition and metabolic profile of various microbial communities are becoming increasingly common, yet new computational methods are needed to integrate and interpret these data in terms of known biological mechanisms. Here, we introduce an analytical framework to link species composition and metabolite measurements, using a simple model to predict the effects of community ecology on metabolite concentrations and evaluating whether these predictions agree with measured metabolomic profiles. We find that a surprisingly large proportion of metabolite variation in the vaginal microbiome can be predicted based on species composition (including dramatic shifts associated with disease), identify putative mechanisms underlying these predictions, and evaluate the roles of individual bacterial species and genes. Analysis of gut microbiome data using this framework recovers similar community metabolic trends. This framework lays the foundation for model-based multi-omic integrative studies, ultimately improving our understanding of microbial community metabolism. PMID:27239563

Rb-Sr systematics and REE abundances in Shalka and several other diogenites

NASA Astrophysics Data System (ADS)

Takahashi, K.; Yabuki, S.; Kagi, H.; Masuda, A.

1994-07-01

The diogenites have been regarded as igneous products in the early solar system and they have been considered to have genetically close relationship with eucrites. Depsite their simple mineralogical compositions and narrow range for major-element compositions, diogenites have been known to show wide Rare Earth Elements (REE) variations in absolute concentration and in mutual abundance ratios. Furthermore, some diogenites have peculiar Rb-Sr isotope systematics (ages younger than 4.5 b.y.). The Shalka meteorite belongs to the diogenites, and a unique REE abundance pattern has been reported. We performed Rb-Sr isotopic analyses and measured REE abundances in the Shalka diogenite with several other diogenites to discuss their genesis. Roughly speaking, REE patterns in diogenites are characterized by the negative Eu anomaly and the depletion of light REE. For Shalka, some heterogeneity in REE abundance patterns have been observed. While one sample chip shows the REE pattern with a large negative Eu anomaly and depleted light REE, particularly characterized by the concave curvature for the La-Nd span, other samples show the pattern nearly flat or the pattern enriched in light REE. These variations could not be explained easily by the simple mixing process of LREE-depleted components and LREE-enriched melt, but they imply some metamorphism process. The Rb-Sr isotopic data for Shalka are shown with the data for other several diogenites. These observations indicate that Shalka would undergo a significant extent of metamorphism followed by redistribution of REE and the disturbance of the Rb-Sr systematics. We are going to do further studies on Shalka to discuss the metamorphic process and compare it with other diogenites.

Systematic Review of Ossicular Chain Anatomy: Strategic Planning for Development of Novel Middle Ear Prostheses.

PubMed

Kamrava, Brandon; Roehm, Pamela C

2017-08-01

Objective To systematically review the anatomy of the ossicular chain. Data Sources Google Scholar, PubMed, and otologic textbooks. Review Methods A systematic literature search was performed on January 26, 2015. Search terms used to discover articles consisted of combinations of 2 keywords. One keyword from both groups was used: [ ossicular, ossicle, malleus, incus, stapes] and [ morphology, morphometric, anatomy, variation, physiology], yielding more than 50,000 hits. Articles were then screened by title and abstract if they did not contain information relevant to human ossicular chain anatomy. In addition to this search, references of selected articles were studied as well as suggested relevant articles from publication databases. Standard otologic textbooks were screened using the search criteria. Results Thirty-three sources were selected for use in this review. From these studies, data on the composition, physiology, morphology, and morphometrics were acquired. In addition, any correlations or lack of correlations between features of the ossicular chain and other features of the ossicular chain or patient were noted, with bilateral symmetry between ossicles being the only important correlation reported. Conclusion There was significant variation in all dimensions of each ossicle between individuals, given that degree of variation, custom fitting, or custom manufacturing of prostheses for each patient could optimize prosthesis fit. From published data, an accurate 3-dimensional model of the malleus, incus, and stapes can be created, which can then be further modified for each patient's individual anatomy.

Perspective: Composition–structure–property mapping in high-throughput experiments: Turning data into knowledge

DOE PAGES

Hattrick-Simpers, Jason R.; Gregoire, John M.; Kusne, A. Gilad

2016-05-26

With their ability to rapidly elucidate composition-structure-property relationships, high-throughput experimental studies have revolutionized how materials are discovered, optimized, and commercialized. It is now possible to synthesize and characterize high-throughput libraries that systematically address thousands of individual cuts of fabrication parameter space. An unresolved issue remains transforming structural characterization data into phase mappings. This difficulty is related to the complex information present in diffraction and spectroscopic data and its variation with composition and processing. Here, we review the field of automated phase diagram attribution and discuss the impact that emerging computational approaches will have in the generation of phase diagrams andmore » beyond.« less

APPLICABILITY OF La-Ce SYSTEMATICS TO PLANETARY SAMPLES.

USGS Publications Warehouse

Nakamura, Noboru; Tatsumoto, Mitsunobu; Ludwig, Kenneth R.

1984-01-01

Ce isotopic compositions in several terrestrial and extraterrestrial materials were determined in order to investigate the applicability of using Ce as an isotopic tracer to geological processes. Owing to the low abundances of **1**3**8La and **1**3**8Ce in nature, the measurements of **1**3**8Ce/**1**4**0Ce ratios of natural samples have relatively large ( greater than 0. 02%) errors, and the variations in Ce-isotope ratios were barely resolved. A tenuous anticorrelation was observed between epsilon //C//e and epsilon //N//d for terrestrial basalts and granites, indicating that with some improvement in analytical techniques the Ce isotopic composition may prove useful as a tracer for geological processes.

Sr, Nd and Pb Isotope Geochemistry of Near-ridge Seamounts in Eastern Pacific: Implications for Upper Mantle Composition and EPR Magmatic Segmentation

NASA Astrophysics Data System (ADS)

Castillo, P. R.; White, W. M.; Batiza, R.

2005-12-01

Near-ridge seamount lavas tend to reflect the true composition of the upper mantle source of MORB because these are generated by relatively smaller degrees of melting of smaller volumes of the mantle compared to nearby axial lavas; they also by-pass the axial chamber mixing and fractionation processes that are responsible for the relatively more uniform chemical and isotopic composition of normal-MORB. New Sr, Nd and Pb isotope data combined with published data for lavas from near-ridge seamounts on either side of the EPR segment between the 11o45' OSC and Orozco Transform at 15o00' show latitudinal isotopic variation very similar to that shown by the rise axial lavas (Castillo et al., G3 1, 1999). Seamount and axial lavas at both ends of the rise segment have on average slightly higher and more limited range of 143Nd/144Nd, but slightly lower 206Pb/204Pb and 87Sr/86Sr ratios than lavas at the center of the segment. Some of the seamounts are located on ~8 Ma rise flank crust although most of the seamount lavas are fairly young (e.g., lavas from Seamount 6 on ~3 Ma crust are only 3 to 900 kyr - Graham et al., Nature 326, 1987). Thus near-ridge seamount isotope data provide the first documentation for a large-scale (~350 km long x ~720 km wide), systematic compositional variation of the upper mantle source of EPR MORB. Such a scale of variation is larger and longer than the size and <1 myr life span of the majority of non-transform offsets, which are supposed to be responsible for the along-axis compositional variations of EPR MORB according to the "bottoms up" model of magmatic segmentation.

Characterizing fish community diversity across Virginia landscapes: Prerequisite for conservation

USGS Publications Warehouse

Angermeier, P.L.; Winston, M.R.

1999-01-01

The number of community types occurring within landscapes is an important, but often unprotected, component of biological diversity. Generally applicable protocols for characterizing community diversity need to be developed to facilitate conservation. We used several multivariate techniques to analyze geographic variation in the composition of fish communities in Virginia streams. We examined relationships between community composition and six landscape variables: drainage basin, physiography, stream order, elevation, channel slope, and map coordinates. We compared patterns at two scales (statewide and subdrainage-specific) to assess sensitivity of community classification to spatial scale. We also compared patterns based on characterizing communities by species composition vs. ecological composition. All landscape variables explained significant proportions of the variance in community composition. Statewide, they explained 32% of the variance in species composition and 48% of the variance in ecological composition. Typical communities in each drainage or physiography were statistically distinctive. Communities in different combinations of drainage, physiography, and stream size were even more distinctive, but composition was strongly spatially autocorrelated. Ecological similarity and species similarity of community pairs were strongly related, but replacement by ecologically similar species was common among drainage-physiography combinations. Landscape variables explained significant proportions of variance in community composition within selected subdrainages, but proportions were less than at the statewide scale, and the explanatory power of individual variables varied considerably among subdrainages. Community variation within subdrainages appeared to be much more closely related to environmental variation than to replacement among ecologically similar species. Our results suggest that taxonomic and ecological characterizations of community composition are complementary; both are useful in a conservation context. Landscape features such as drainage, physiography, and water body size generally may provide a basis for assessing aquatic community diversity, especially in regions where the biota is poorly known. Systematic conservation of community types would be a major advance relative to most current conservation programs, which typically focus narrowly on populations of imperiled species. More effective conservation of aquatic biodiversity will require new approaches that recognize the value of both species and assemblages, and that emphasize protection of key landscape-scale processes.

Systematic study of electron-phonon coupling to oxygen modes across the cuprates

NASA Astrophysics Data System (ADS)

Johnston, S.; Vernay, F.; Moritz, B.; Shen, Z.-X.; Nagaosa, N.; Zaanen, J.; Devereaux, T. P.

2010-08-01

The large variations in Tc across the cuprate families is one of the major unsolved puzzles in condensed matter physics and is poorly understood. Although there appears to be a great deal of universality in the cuprates, several orders of magnitude changes in Tc can be achieved through changes in the chemical composition and structure of the unit cell. In this paper we formulate a systematic examination of the variations in electron-phonon coupling to oxygen phonons in the cuprates, incorporating a number of effects arising from several aspects of chemical composition and doping across cuprate families. It is argued that the electron-phonon coupling is a very sensitive probe of the material-dependent variations in chemical structure, affecting the orbital character of the band crossing the Fermi level, the strength of local electric fields arising from structural-induced symmetry breaking, doping-dependent changes in the underlying band structure, and ionicity of the crystal governing the ability of the material to screen c -axis perturbations. Using electrostatic Ewald calculations and known experimental structural data, we establish a connection between the material’s maximal Tc at optimal doping and the strength of coupling to c -axis modes. We demonstrate that materials with the largest coupling to the out-of-phase bond-buckling (B1g) oxygen phonon branch also have the largest Tc ’s. In light of this observation we present model Tc calculations using a two-well model where phonons work in conjunction with a dominant pairing interaction, presumably due to spin fluctuations, indicating how phonons can generate sizeable enhancements to Tc despite the relatively small coupling strengths. Combined, these results can provide a natural framework for understanding the doping and material dependence of Tc across the cuprates.

Composition of Apollo 17 core 76001

NASA Technical Reports Server (NTRS)

Korotev, Randy L.; Bishop, Kaylynn M.

1993-01-01

Core 76001 is a single drive tube containing a column of regolith taken at the base of the North Massif, station 6, Apollo 17. The core material is believed to have accumulated through slow downslope mass wasting from the massif. As a consequence, the core soil is mature throughout its length. Results of INAA for samples taken every half centimeter along the length of the core indicate that there is only minor systematic compositional variation with depth. Concentrations of elements primarily associated with mare basalt (Sc, Fe) and noritic impact melt breccia (Sm) decrease slightly with depth, particularly between 20 cm and the bottom of the core at 32 cm depth. This is consistent with petrographic studies that indicate a greater proportion of basalt and melt breccia in the top part of the core. However, Sm/Sc and La/Sm ratios are remarkably constant with depth, indicating no variation in the ratio of mare material to Sm-rich highlands material with depth. Other than these subtle changes, there is no compositional evidence for the two stratigraphic units (0-20 cm and 20-32 cm) defined on the basis of modal petrography, although all samples with anomalously high Ni concentrations (Fe-Ni metal nuggets) occur above 20 cm depth.

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

Noecker, Cecilia; Eng, Alexander; Srinivasan, Sujatha

ABSTRACT Multiple molecular assays now enable high-throughput profiling of the ecology, metabolic capacity, and activity of the human microbiome. However, to date, analyses of such multi-omic data typically focus on statistical associations, often ignoring extensive prior knowledge of the mechanisms linking these various facets of the microbiome. Here, we introduce a comprehensive framework to systematically link variation in metabolomic data with community composition by utilizing taxonomic, genomic, and metabolic information. Specifically, we integrate available and inferred genomic data, metabolic network modeling, and a method for predicting community-wide metabolite turnover to estimate the biosynthetic and degradation potential of a given community.more » Our framework then compares variation in predicted metabolic potential with variation in measured metabolites’ abundances to evaluate whether community composition can explain observed shifts in the community metabolome, and to identify key taxa and genes contributing to the shifts. Focusing on two independent vaginal microbiome data sets, each pairing 16S community profiling with large-scale metabolomics, we demonstrate that our framework successfully recapitulates observed variation in 37% of metabolites. Well-predicted metabolite variation tends to result from disease-associated metabolism. We further identify several disease-enriched species that contribute significantly to these predictions. Interestingly, our analysis also detects metabolites for which the predicted variation negatively correlates with the measured variation, suggesting environmental control points of community metabolism. Applying this framework to gut microbiome data sets reveals similar trends, including prediction of bile acid metabolite shifts. This framework is an important first step toward a system-level multi-omic integration and an improved mechanistic understanding of the microbiome activity and dynamics in health and disease. IMPORTANCEStudies characterizing both the taxonomic composition and metabolic profile of various microbial communities are becoming increasingly common, yet new computational methods are needed to integrate and interpret these data in terms of known biological mechanisms. Here, we introduce an analytical framework to link species composition and metabolite measurements, using a simple model to predict the effects of community ecology on metabolite concentrations and evaluating whether these predictions agree with measured metabolomic profiles. We find that a surprisingly large proportion of metabolite variation in the vaginal microbiome can be predicted based on species composition (including dramatic shifts associated with disease), identify putative mechanisms underlying these predictions, and evaluate the roles of individual bacterial species and genes. Analysis of gut microbiome data using this framework recovers similar community metabolic trends. This framework lays the foundation for model-based multi-omic integrative studies, ultimately improving our understanding of microbial community metabolism.« less

Temporal variation in chemical composition of phenocrysts and magmatic temperature at Daisen volcano, southwest Japan

NASA Astrophysics Data System (ADS)

Tsukui, Masashi

1985-12-01

Daisen volcano, located in the San'in district, southwest Japan, started its activity in the middle Pleistocene and continued until at least ca. 20,000 yr B.P. The volcano is composed entirely of dacitic pyroclastic materials, lava domes and subordinate thick lava flows. Its activity is divided into two groups, Older (1.0-0.4 Ma) and Younger (0.4 Ma to ca. 17.000 yr B.P.). Chemical compositions of phenocrysts in the members of the Upper Tephra Group (the last 150,000 years) in the Younger Group were examined in detail by electron microprobe analysis. The compositions of phenocryst minerals change systematically and cyclically with the order of eruptions. Phenocrysts with less differentiated compositions were found in the products of eruptions 60,000 and 20,000 years ago. The variation patterns of inferred magma temperature (estimated by the Fe-Ti oxide geothermometer) with time are well correlated with those of the chemical compositions of phenocrysts. Orthopyroxene phenocrysts generally show both reversed and normal zoning in single rock specimens and the compositional range of rims is much smaller than that of the core, indicating that the process of re-equilibration of two compositionally distinct orthopyroxenes took place. These facts could be explained by injection of less differentiated, higher-temperature magmas from a deeper level into the shallower more differentiated magma reservoir. A relatively active (frequent and/or voluminous) injection episode seems to have taken place twice during the last 150,000 years; 60,000 and 20,000 years ago.

Contrasting spatial patterns and ecological attributes of soil bacterial and archaeal taxa across a landscape

PubMed Central

Constancias, Florentin; Saby, Nicolas P A; Terrat, Sébastien; Dequiedt, Samuel; Horrigue, Wallid; Nowak, Virginie; Guillemin, Jean-Philippe; Biju-Duval, Luc; Chemidlin Prévost-Bouré, Nicolas; Ranjard, Lionel

2015-01-01

Even though recent studies have clarified the influence and hierarchy of environmental filters on bacterial community structure, those constraining bacterial populations variations remain unclear. In consequence, our ability to understand to ecological attributes of soil bacteria and to predict microbial community response to environmental stress is therefore limited. Here, we characterized the bacterial community composition and the various bacterial taxonomic groups constituting the community across an agricultural landscape of 12 km2, by using a 215 × 215 m systematic grid representing 278 sites to precisely decipher their spatial distribution and drivers at this scale. The bacterial and Archaeal community composition was characterized by applying 16S rRNA gene pyrosequencing directly to soil DNA from samples. Geostatistics tools were used to reveal the heterogeneous distribution of bacterial composition at this scale. Soil physical parameters and land management explained a significant amount of variation, suggesting that environmental selection is the major process shaping bacterial composition. All taxa systematically displayed also a heterogeneous and particular distribution patterns. Different relative influences of soil characteristics, land use and space were observed, depending on the taxa, implying that selection and spatial processes might be differentially but not exclusively involved for each bacterial phylum. Soil pH was a major factor determining the distribution of most of the bacterial taxa and especially the most important factor explaining the spatial patterns of α-Proteobacteria and Planctomycetes. Soil texture, organic carbon content and quality were more specific to a few number of taxa (e.g., β-Proteobacteria and Chlorobi). Land management also influenced the distribution of bacterial taxa across the landscape and revealed different type of response to cropping intensity (positive, negative, neutral or hump-backed relationships) according to phyla. Altogether, this study provided valuable clues about the ecological behavior of soil bacterial and archaeal taxa at an agricultural landscape scale and could be useful for developing sustainable strategies of land management. PMID:25922908

Systematic and random variations in digital Thematic Mapper data

NASA Technical Reports Server (NTRS)

Duggin, M. J. (Principal Investigator); Sakhavat, H.

1985-01-01

Radiance recorded by any remote sensing instrument will contain noise which will consist of both systematic and random variations. Systematic variations may be due to sun-target-sensor geometry, atmospheric conditions, and the interaction of the spectral characteristics of the sensor with those of upwelling radiance. Random variations in the data may be caused by variations in the nature and in the heterogeneity of the ground cover, by variations in atmospheric transmission, and by the interaction of these variations with the sensing device. It is important to be aware of the extent of random and systematic errors in recorded radiance data across ostensibly uniform ground areas in order to assess the impact on quantative image analysis procedures for both the single date and the multidate cases. It is the intention here to examine the systematic and the random variations in digital radiance data recorded in each band by the thematic mapper over crop areas which are ostensibly uniform and which are free from visible cloud.

D/H Ratios of Marine Lipids from Santa Barbara Basin Sediments

NASA Astrophysics Data System (ADS)

Li, C.; Sessions, A.; Kinnaman, F.; Valentine, D.

2006-12-01

With the early successful application of compound-specific D/H analyses to reconstructing paleoclimate records, most subsequent research has focused on understanding organic D/H fractionations in terrestrial environments. Thus we still know very little about natural D/H variations in lipids derived from marine organisms, or indeed if any such variations exist. We have therefore conducted an extensive survey of lipid δD values in two sediment cores collected in the Santa Barbara Basin. These data allow us to examine 1) variations between the lipid products of different organisms, 2) down-core variations due to diagenesis, and 3) differences between sediments deposited under oxic or anoxic bottom-water conditions. Our results show that considerable D/H variability between different marine products does exist. δD values of n-alkanes (except n-C35) ranged from -94 to -175 ‰, and exhibit a systematic offset between odd and even carbon numbers. The δD value of n-C35 is anomalous at -220‰. Isotopic compositions of n-alkanols range from -126 to -221 , with a pattern of progressive D depletion with chain length observed for free alcohols. δD values of sterols range from -215 to -309‰, and show no systematic variation with carbon number. However, offsets do exist between the saturated, monounsaturated, and diunsaturated sterols. Sterols as a group are strongly depleted in D relative to the bacterial-derived hopanols (-166 to -232‰), suggesting possible differences in biosynthetic fractionations by bacteria and eukaryotes. Phytol and phytane δD values roughly ranged from -360 to -410‰, while phytanol was systematically enriched at -300 to -340‰. Fatty acids encompassed much greater variability, with dD values ranging from -55 to -270‰. In general, saturated fatty acids are enriched in D relative to their unsaturated analogs, and long-chain (>C24) acids are enriched in D relative to short-chain (

Curing potential of experimental resin composites with systematically varying amount of bioactive glass: Degree of conversion, light transmittance and depth of cure.

PubMed

Par, Matej; Spanovic, Nika; Bjelovucic, Ruza; Skenderovic, Hrvoje; Gamulin, Ozren; Tarle, Zrinka

2018-06-17

The aim of this work was to investigate the curing potential of an experimental resin composite series with the systematically varying amount of bioactive glass 45S5 by evaluating the degree of conversion, light transmittance and depth of cure. Resin composites based on a Bis-GMA/TEGDMA resin with a total filler load of 70 wt% and a variable amount of bioactive glass (0-40 wt%) were prepared. The photoinitiator system was camphorquinone and ethyl-4-(dimethylamino) benzoate. The degree of conversion and light transmittance were measured by Raman spectroscopy and UV-vis spectroscopy, respectively. The depth of cure was evaluated according to the classical ISO 4049 test. The initial introduction of bioactive glass into the experimental series diminished the light transmittance while the further increase in the bioactive glass amount up to 40 wt% caused minor variations with no clear trend. The curing potential of the experimental composites was similar to or better than that of commercial resin composites. However, unsilanized bioactive glass fillers demonstrated the tendency to diminish both the maximum attainable conversion and the curing efficiency at depth. Experimental composite materials containing bioactive glass showed a clinically acceptable degree of conversion and depth of cure. The degree of conversion and depth of cure were diminished by bioactive glass fillers in a dose-dependent manner, although light transmittance was similar among all of the experimental composites containing 5-40 wt% of bioactive glass. Reduced curing potential caused by the bioactive glass has possible consequences on mechanical properties and biocompatibility. Copyright © 2018 Elsevier Ltd. All rights reserved.

Concordant Rb-Sr and Sm-Nd Ages for NWA 1460: A 340 Ma Old Basaltic Shergottite Related to Lherzolitic Shergottites

NASA Technical Reports Server (NTRS)

Nyquist, L. E.; Shih, C-Y; Reese, Y. D.; Irving, A. J.

2006-01-01

Preliminary Rb-Sr and Sm-Nd ages reported by [1] for the NWA 1460 basaltic shergottite are refined to 336+/-14 Ma and 345+/-21 Ma, respectively. These concordant ages are interpreted as dating a lava flow on the Martian surface. The initial Sr and Nd isotopic compositions of NWA 1460 suggest it is an earlier melting product of a Martian mantle source region similar to those of the lherzolitic shergottites and basaltic shergottite EETA79001, lithology B. We also examine the suggestion that generally "young" ages for other Martian meteorites should be reinterpreted in light of Pb-207/Pb-206 - Pb-204/Pb-206 isotopic systematics [2]. Published U-Pb isotopic data for nakhlites are consistent with ages of approx.1.36 Ga. The UPb isotopic systematics of some Martian shergottites and lherzolites that have been suggested to be approx.4 Ga old [2] are complex. We nevertheless suggest the data are consistent with crystallization ages of approx.173 Ma when variations in the composition of in situ initial Pb as well as extraneous Pb components are considered.

Temperature Dependent Electron Transport Properties of Gold Nanoparticles and Composites: Scanning Tunneling Spectroscopy Investigations.

PubMed

Patil, Sumati; Datar, Suwarna; Dharmadhikari, C V

2018-03-01

Scanning tunneling spectroscopy (STS) is used for investigating variations in electronic properties of gold nanoparticles (AuNPs) and its composite with urethane-methacrylate comb polymer (UMCP) as function of temperature. Films are prepared by drop casting AuNPs and UMCP in desired manner on silicon substrates. Samples are further analyzed for morphology under scanning electron microscopy (SEM) and atomic force microscopy (AFM). STS measurements performed in temperature range of 33 °C to 142 °C show systematic variation in current versus voltage (I-V) curves, exhibiting semiconducting to metallic transition/Schottky behavior for different samples, depending upon preparation method and as function of temperature. During current versus time (I-t) measurement for AuNPs, random telegraphic noise is observed at room temperature. Random switching of tunneling current between two discrete levels is observed for this sample. Power spectra derived from I-t show 1/f2 dependence. Statistical analysis of fluctuations shows exponential behavior with time width τ ≈ 7 ms. Local density of states (LDOS) plots derived from I-V curves of each sample show systematic shift in valance/conduction band edge towards/away from Fermi level, with respect to increase in temperature. Schottky emission is best fitted electron emission mechanism for all samples over certain range of bias voltage. Schottky plots are used to calculate barrier heights and temperature dependent measurements helped in measuring activation energies for electron transport in all samples.

Sampling and major element chemistry of the recent (A.D. 1631-1944) Vesuvius activity

USGS Publications Warehouse

Belkin, H.E.; Kilburn, C.R.J.; de Vivo, B.

1993-01-01

Detailed sampling of the Vesuvius lavas erupted in the period A.D. 1631-1944 provides a suite of samples for comprehensive chemical analyses and related studies. Major elements (Si, Ti, Al, Fetotal, Mn, Mg, Ca, Na, K and P), volatile species (Cl, F, S, H2O+, H2O- and CO2), and ferrous iron (Fe2+) were determined for one hundred and forty-nine lavas and five tephra from the A.D. 1631-1944 Vesuvius activity. The lavas represent a relatively homogeneous suite with respect to SiO2, TiO2, FeOtotal, MnO and P2O5, but show systematic variations among MgO, K2O, Na2O, Al2O3 and CaO. The average SiO2 content is 48.0 wt.% and the rocks are classified as tephriphonolites according to their content of alkalis. All of the lavas are silica-undersaturated and are nepheline, leucite, and olivine normative. There is no systematic variation in major-element composition with time, over the period A.D. 1631-1944. The inter-eruption and intra-eruption compositional differences are the same magnitude. The lavas are highly porphyritic with clinopyroxene and leucite as the major phases. Fractionation effects are not reflected in the silica content of the lavas. The variability of MgO, K2O, Na2O, and CaO can be modelled as a relative depletion or accumulation of clinopyroxene. ?? 1993.

A 1400 km geochemical transect along the Central American Arc: Summary of mafic Holocene volcanism from Guatemala to Panama

NASA Astrophysics Data System (ADS)

Geldmacher, J.; Hoernle, K.; Gill, J. B.; Hauff, F.; Heydolph, K.

2016-12-01

It is generally accepted that subducted oceanic crust and sediments contribute to the composition of arc magmas. Systematic variations of input parameters (including age, subduction angle, and chemical composition of the subducting material) make the Central American Volcanic Arc (CAVA), which extends from Guatemala in the northwest through El Salvador, Honduras, Nicaragua, Costa Rica and Panama to the southeast, a prime study object. We present a comprehensive (major and trace element and Sr-Nd-Pb-Hf isotope data) and consistent (all data generated in the same labs using the same methods and data reduction procedures) compilation of published and unpublished Holocene mafic volcanic rocks sampled along the entire arc. New data include Sr and, for the first time, Hf isotope data from the entire CAVA as well as major and trace element data for 43 samples from southern Nicaragua and central Costa Rica from which only isotopic compositions were previously published. The combined elemental and isotopic data confirm the influence of distinct subduction components on the composition of CAVA magmas. Along-arc geochemical variations (especially delta 208Pb/204Pb) of volcanic front magmas in Costa Rica and Panama have been explained by the different compositions of seamounts/ridges of the isotopically zoned Galápagos hotspot track that covers the subducting Cocos Plate in this sector of the arc (Hoernle et al. 2008, Nature 451). Our new data confirm this relationship with arc lavas from Costa Rica having higher 87Sr/86Sr ratios than those from western Panama reflecting a similar spatial-compositional distinction in the subducting hotspot track beneath them. In contrast, 176Hf/177Hf shows no comparable variations in this sector of the arc, indicating that the Hf is primarily derived from the mantle wedge rather than the subducting slab. Although small degree hydrous melts are believed to fertilize the mantle wedge beneath Costa Rica, residual zircon may hold back the Hf.

Biomarker patterns in present-day vegetation: consistency and variation - A study on plaggen soils

NASA Astrophysics Data System (ADS)

Kirkels, Frédérique; Jansen, Boris; Kalbitz, Karsten

2013-04-01

Biomarker patterns in present-day vegetation are commonly used as proxies to reconstruct paleo-vegetation composition, land use history and to elucidate carbon cycling. Plaggen soils are formed by diverse vegetational inputs during century-long plaggen (i.e. sod) application associated with plaggen-agriculture on poor soils in north-western Europe. This resulted in remarkably stable organic matter. Plant source identification by biomarkers could provide insight in yet unknown stabilization mechanisms and the fate of organic matter upon ongoing land use change. The current rationale behind biomarker-based source identification is that patterns observed in present-day vegetation are generally representative with little random variation. However, our knowledge on variability and consistency of biomarker patterns is yet scarce. Therefore, to assess the applicability of biomarkers for source identification in plaggen soils, we analyzed published n-alkane and n-alcohol patterns of species and their various parts which contribute(d) input to plaggen soils. We considered shrubs, trees and grass species and evaluated rescaled patterns (i.e. relative abundances in chain-length range C17-36), odd-over-even predominance (OEP) and predominant n-alkanes. In addition, we explicitly looked into potential sources of systematic variation, e.g. spatial variation (climate, site conditions), temporal variation (seasonality, ontogeny) and laboratory methodology (extraction technique: washing/shaking, Soxhlet/ASE, saponification). We found meaningful clustering of n-alkanes C27, C29, C31 and C33, allowing for clear distinction of input by shrubs, trees and grasses to plaggen soils. Combination of these homologues with complete n-alkane patterns (C17-36) and OEP enabled further differentiation, while n-alcohols patterns were less distinct. Current limitation is the lack of extended and diverse quantitative records on biomarker patterns, especially for n-alcohols, non-leaf and belowground tissues, which hindered full statistical analysis. On species level we also recognized outliers and spreading. Systematic variation was indicated among tree species according to spatial conditions and by ontogeny. Yet, observed effects were ambiguous for other variation sources. This study highlights clear opportunities for application of biomarker patterns for source identification and elucidation of stabilization processes in (plaggen) soils. At the same time, application is challenged by systematic variation. Further research is key to quantify controls, magnitude and potential correction factors for such systematic variation. This would validate the use of n-alkane and n-alcohol patterns across broad spatial and temporal scales or identify boundaries wherein their consistency is ensured. Likely, these challenges apply to vegetation in a broad perspective, transcending plaggen vegetation, as assessment and application of present-day vegetation patterns is emerging.

Olivine and chromian spinel in primitive calc-alkaline and tholeiitic lavas from the southernmost cascade range, California: A reflection of relative fertility of the source

USGS Publications Warehouse

Clynne, M.A.; Borg, L.E.

1997-01-01

Chromian spinel and coexisting olivine phenocrysts from a geochemically diverse suite of primitive tholeiitic and calc-alkaline basalts and magnesian andesites from the Lassen region, in the southernmost Cascade Range, in California, show that the sub-arc mantle is zoned. Depleted calc-alkaline basalts and magnesian andesites erupt in the forearc region, and calc-alkaline basalts contain increasing abundances of incompatible elements toward the backarc. High-alumina olivine tholeiites erupt from the arc and backarc areas. Olivine from all these lavas displays a limited compositional range, from Fo86 to Fo91, and crystallized at high temperature, generally 1225-1275??C. Chromian spinel trapped in the olivine phenocrysts displays a large range of composition: Cr# values span the range 9-76. Excess Al in the spinel relative to that in 1-atm spinel suggests that it crystallized at elevated pressure. The phenocrysts in these lavas are in equilibrium with their host liquids. The full range of Cr# of the spinel compositions cannot be explained by differentiation or variable pressure, variations in f(O2), subsolidus equilibration or variations in degree of partial melting of a single peridotitic source. Rather, the systematic compositional differences among phenocrysts in these primitive lavas result from bulk chemical variability in their mantle sources. Correlations between spinel and host-rock compositions support the assertion that the geochemical diversity of Lassen basalts reflects the relative fertility of their mantle sources.

Temperature and composition dependencies of trace element partitioning - Olivine/melt and low-Ca pyroxene/melt

NASA Technical Reports Server (NTRS)

Colson, R. O.; Mckay, G. A.; Taylor, L. A.

1988-01-01

This paper presents a systematic thermodynamic analysis of the effects of temperature and composition on olivine/melt and low-Ca pyroxene/melt partitioning. Experiments were conducted in several synthetic basalts with a wide range of Fe/Mg, determining partition coefficients for Eu, Ca, Mn, Fe, Ni, Sm, Cd, Y, Yb, Sc, Al, Zr, and Ti and modeling accurately the changes in free energy for trace element exchange between crystal and melt as functions of the trace element size and charge. On the basis of this model, partition coefficients for olivine/melt and low-Ca pyroxene/melt can be predicted for a wide range of elements over a variety of basaltic bulk compositions and temperatures. Moreover, variations in partition coeffeicients during crystallization or melting can be modeled on the basis of changes in temperature and major element chemistry.

Parametric study using modal analysis of a bi-material plate with defects

NASA Astrophysics Data System (ADS)

Esola, S.; Bartoli, I.; Horner, S. E.; Zheng, J. Q.; Kontsos, A.

2015-03-01

Global vibrational method feasibility as a non-destructive inspection tool for multi-layered composites is evaluated using a simulated parametric study approach. A finite element model of a composite consisting of two, isotropic layers of dissimilar materials and a third, thin isotropic layer of adhesive is constructed as the representative test subject. Next, artificial damage is inserted according to systematic variations of the defect morphology parameters. A free-vibrational modal analysis simulation is executed for pristine and damaged plate conditions. Finally, resultant mode shapes and natural frequencies are extracted, compared and analyzed for trends. Though other defect types may be explored, the focus of this research is on interfacial delamination and its effects on the global, free-vibrational behavior of a composite plate. This study is part of a multi-year research effort conducted for the U.S. Army Program Executive Office - Soldier.

Physics of systematic frequency variations in hydrogen masers

NASA Technical Reports Server (NTRS)

Mattison, Edward M.

1990-01-01

The frequency stability of hydrogen masers for intervals longer that 10(exp 4) seconds is limited at present by systematic processes. Researchers discuss the physics of frequency-determining mechanisms internal to the maser that are susceptible to systematic variations, and the connections between these internal mechanisms and external environmental factors. Based upon estimates of the magnitudes of systematic effects, they find that the primary internal mechanisms currently limiting long-term maser frequency stability are cavity pulling, at the level parts in 10(exp 15) per day, and wall shift variations, at the level of parts in 10(exp 16) to parts in 10(exp 15) per day. They discuss strategies for reducing systematic frequency variations.

Physics of systematic frequency variations in hydrogen masers

NASA Technical Reports Server (NTRS)

Mattison, Edward M.

1992-01-01

The frequency stability of hydrogen masers for intervals longer than 10 exp 4 s is currently limited by systematic processes. The physics of frequency-determining mechanisms internal to the maser that are susceptible to systematic variations, and the connections between these internal mechanisms and external environmental factors are discussed. From estimates of the magnitudes of systematic effects, it is found that the primary internal mechanisms limiting long-term maser frequency stability are cavity pulling, at the level of parts in 1015 per day, and wall shift variations, at the level of parts in 10 exp 16 to parts in 10 exp 15 per day. Strategies for reducing systematic frequency variations are discussed.

SYSTEMATIC CENTER-TO-LIMB VARIATION IN MEASURED HELIOSEISMIC TRAVEL TIMES AND ITS EFFECT ON INFERENCES OF SOLAR INTERIOR MERIDIONAL FLOWS

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

Zhao Junwei; Nagashima, Kaori; Bogart, R. S.

We report on a systematic center-to-limb variation in measured helioseismic travel times, which must be taken into account for an accurate determination of solar interior meridional flows. The systematic variation, found in time-distance helioseismology analysis using SDO/HMI and SDO/AIA observations, is different in both travel-time magnitude and variation trend for different observables. It is not clear what causes this systematic effect. Subtracting the longitude-dependent east-west travel times, obtained along the equatorial area, from the latitude-dependent north-south travel times, obtained along the central meridian area, gives remarkably similar results for different observables. We suggest this as an effective procedure for removingmore » the systematic center-to-limb variation. The subsurface meridional flows obtained from inversion of the corrected travel times are approximately 10 m s{sup -1} slower than those obtained without removing the systematic effect. The detected center-to-limb variation may have important implications in the derivation of meridional flows in the deep interior and needs to be better understood.« less

Systematic Center-To-Limb Variation in Measured Helioseismic Travel Times and Its Effect on Inferences of Solar Interior Meridional Flows

NASA Technical Reports Server (NTRS)

Zhao, Junwei; Nagashima, Kaori; Bogart, R. S.; Kosovichev, Alexander; Duvall, T. L., Jr.

2012-01-01

We report on a systematic center-to-limb variation in measured helioseismic travel times, which must be taken into account for an accurate determination of solar interior meridional flows. The systematic variation, found in time-distance helioseismology analysis using SDO/HMI and SDO/AIA observations, is different in both travel-time magnitude and variation trend for different observables. It is not clear what causes this systematic effect. Subtracting the longitude-dependent east-west travel times, obtained along the equatorial area, from the latitude-dependent north-south travel times, obtained along the central meridian area, gives remarkably similar results for different observables. We suggest this as an effective procedure for removing the systematic center-to-limb variation. The subsurface meridional flows obtained from inversion of the corrected travel times are approximately 10 m s-1 slower than those obtained without removing the systematic effect. The detected center-to-limb variation may have important implications in the derivation of meridional flows in the deep interior and needs to be better understood.

Petrological systematics of mid-ocean ridge basalts: Constraints on melt generation beneath ocean ridges

NASA Astrophysics Data System (ADS)

Langmuir, Charles H.; Klein, Emily M.; Plank, Terry

Mid-ocean ridge basalts (MORB) are a consequence of pressure-release melting beneath ocean ridges, and contain much information concerning melt formation, melt migration and heterogeneity within the upper mantle. MORB major element chemical systematics can be divided into global and local aspects, once they have been corrected for low pressure fractionation and interlaboratory biases. Regional average compositions for ridges unaffected by hot spots ("normal" ridges) can be used to define the global correlations among normalized Na2O, FeO, TiO2 and SiO2 contents, CaO/Al2O3 ratios, axial depth and crustal thickness. Back-arc basins show similar correlations, but are offset to lower FeO and TiO2 contents. Some hot spots, such as the Azores and Galapagos, disrupt the systematics of nearby ridges and have the opposite relationships between FeO, Na2O and depth over distances of 1000 km. Local variations in basalt chemistry from slow- and fast-spreading ridges are distinct from one another. On slow-spreading ridges, correlations among the elements cross the global vector of variability at a high angle. On the fast-spreading East Pacific Rise (EPR), correlations among the elements are distinct from both global and slow-spreading compositional vectors, and involve two components of variation. Spreading rate does not control the global correlations, but influences the standard deviations of axial depth, crustal thickness, and MgO contents of basalts. Global correlations are not found in very incompatible trace elements, even for samples far from hot spots. Moderately compatible trace elements for normal ridges, however, correlate with the major elements. Trace element systematics are significantly different for the EPR and the mid-Atlantic Ridge (MAR). Normal portions of the MAR are very depleted in REE, with little variability; hot spots cause large long wavelength variations in REE abundances. Normal EPR basalts are significantly more enriched than MAR basalts from normal ridges, and still more enriched basalts can erupt sporadically along the entire length of the EPR. This leads to very different histograms of distribution for the data sets as a whole, and a very different distribution of chemistry along strike for the two ridges. Despite these differences, the mean Ce/Sm ratios from the two ridges are identical. Existing methods for calculating the major element compositions of mantle melts [Klein and Langmuir, 1987; McKenzie and Bickle, 1988; Niu and Batiza, 1991] are critically examined. New quantitative methods for mantle melting and high pressure fractionation are developed to evaluate the chemical consequences of melting and fractionation processes and mantle heterogeneity. The new methods rely on new equations for partition coefficients for the major elements between mantle minerals and melts. The melting calculations can be used to investigate the chemical compositions produced by small extents of melting or high pressures of melting that cannot yet be determined experimentally. Application of the new models to the observations described above leads to two major conclusions: (1) The global correlations for normal ridges are caused by variations in mantle temperature, as suggested by Klein and Langmuir [1987] and not by mantle heterogeneity. (2) Local variations are caused by melting processes, but are not yet quantitatively accounted for. On slower spreading ridges, local variations are controlled by the melting regime in the mantle. On the EPR, local variations are predominantly controlled by ubiquitous, small scale heterogeneites. Volatile content may be an important and as yet undetermined factor in affecting the observed variations in major elements. We propose a hypothesis, similar to one proposed by Allegre et al [1984] for isotopic data, to explain the differences between the Atlantic and Pacific local trends, and the trace element systematics of the two ocean basins, as consequences of spreading rate and a different distribution of enriched components from hot spots in the two ocean basins. In the Atlantic, the hot spot influence is in discrete areas, and produces clear depth and chemical anomalies. Ridge segments far from hot spots do not contain enriched basalts. Melting processes associated with slow-spreading ridges vary substantially over short distances along strike and lead to the local trends discussed above, irrespective of hot spot influence. In the Pacific, enriched components appear to have been more thoroughly mixed into the mantle, leading to ubiquitous small scale heterogeneities. Melting processes do not vary appreciably along strike, so local chemical variations are dominated by the relative contribution of enriched component on short time and length scales. Thus the extent of mixing and distribution of enriched components influences strongly the contrasting local major element trends. Despite the difference in the distribution of enriched components, the mean compositions of each data set are equivalent. This suggests that the hot spot influence is similar in the two ocean basins, but its distribution in the upper mantle is different. These contrasting relationships between hot spots and ridges may result from differences in both spreading rate and tectonic history. Unrecognized hot spots may play an important role in diverse aspects of EPR volcanism, and in the chemical systematics of the erupted basalts. The observations and successful models have consequences for melt formation and segregation. (1) The melting process must be closer to fractional melting than equilibrium melting. This result is in accord with inferences from abyssal peridotites [Johnson et al., 1990]. (2) Small melt fractions generated over a range of pressures must be extracted rapidly and efficiently from high pressures within the mantle without experiencing low pressure equilibration during ascent. This requires movement in large channels, and possibly more efficient extraction mechanisms than nonnally envisaged in porous flow models with small residual porosity. (3) Diverse melts from the melting regime produce variations in basalts that are observable at the surface. (4) Basalt data can be used to constrain the melting process (e.g. active vs. passive upwelling) and its relationship to segmentation. The data cannot be used to constrain the shape of the melting regime, however, for many shapes lead to similar chemical results. (5) Highly incompatible elements and U-series disequilibria results appear not yet to be explained by melting models, and may require additional processes not yet clearly envisaged.

Remote compositional analysis of lunar olivine-rich lithologies with Moon Mineralogy Mapper (M3) spectra

USGS Publications Warehouse

Isaacson, P.J.; Pieters, C.M.; Besse, S.; Clark, R.N.; Head, J.W.; Klima, R.L.; Mustard, J.F.; Petro, N.E.; Staid, M.I.; Sunshine, J.M.; Taylor, L.A.; Thaisen, K.G.; Tompkins, S.

2011-01-01

A systematic approach for deconvolving remotely sensed lunar olivine-rich visible to near-infrared (VNIR) reflectance spectra with the Modified Gaussian Model (MGM) is evaluated with Chandrayaan-1 Moon Mineralogy Mapper (M 3) spectra. Whereas earlier studies of laboratory reflectance spectra focused only on complications due to chromite inclusions in lunar olivines, we develop a systematic approach for addressing (through continuum removal) the prominent continuum slopes common to remotely sensed reflectance spectra of planetary surfaces. We have validated our continuum removal on a suite of laboratory reflectance spectra. Suites of olivine-dominated reflectance spectra from a small crater near Mare Moscoviense, the Copernicus central peak, Aristarchus, and the crater Marius in the Marius Hills were analyzed. Spectral diversity was detected in visual evaluation of the spectra and was quantified using the MGM. The MGM-derived band positions are used to estimate the olivine's composition in a relative sense. Spectra of olivines from Moscoviense exhibit diversity in their absorption features, and this diversity suggests some variation in olivine Fe/Mg content. Olivines from Copernicus are observed to be spectrally homogeneous and thus are predicted to be more compositionally homogeneous than those at Moscoviense but are of broadly similar composition to the Moscoviense olivines. Olivines from Aristarchus and Marius exhibit clear spectral differences from those at Moscoviense and Copernicus but also exhibit features that suggest contributions from other phases. If the various precautions discussed here are weighed carefully, the methods presented here can be used to make general predictions of absolute olivine composition (Fe/Mg content). Copyright ?? 2011 by the American Geophysical Union.

Hydrodynamic Controls on Archaeal Tetraether Lipid Compositions in Washington Margin Sediments: Insights From Compound-Specific Radiocarbon Measurements

NASA Astrophysics Data System (ADS)

Uchida, M.; Eglinton, T. I.; Montlucon, D. B.; Pearson, A.; Hayes, J. M.

2008-12-01

Continental margin sediments represent a large sink of organic carbon derived from marine and terrestrial sources. Archaeal glycerol dibiphytanyl glycerol tetraether lipids (GDGTs) are derived from both marine and terrestrial sources and have been used both for reconstruction of paleo sea surface temperatures and as an index of terrestrial carbon input to the marine sediments. However, the sources and modes of supply as well as the preservation of GDGTs in marginal sediments are poorly understood. The distribution and deposition of GDGTs is further complicated by hydrodynamic processes. We have analyzed a suite of surface sediment samples collected along a transect from the mouth of the Columbia River, across the Washington Margin, to the Cascadia Basin in the northeast Pacific Ocean. Sediments were separated according to their grain size and hydrodynamic properties, and the organic matter characterized in terms of its bulk elemental, isotopic, and molecular properties. Here we present radiocarbon measurements on individual GDGTs, alkenones, and fatty acids from size-fractionated sediments from shelf and slope sediments, and discuss the results in the context of previous studies of the molecular abundances and isotopic compositions of sedimentary organic matter for in this region. Systematic variations in elemental, isotopic and molecular-level composition are observed across the different particle classes. Moreover, these variations are manifested in the isotopic composition of different molecular markers of both marine and terrestrial sources organic matter. Both marine-derived lipids, including alkenones and marine archaeal tetraethers, and soil microbe-derived tetraether lipids show strong distributional and isotopic variations among the size-fractionated sediments. These variations in terrestrial and marine biomarker properties inform on the sources, particle dynamics, and transport history of organic matter buried on river-influenced continental margins. The implications of these findings for the application of molecular markers as proxies of organic matter input, and on the interpretation of past marine and continental environmental conditions from sedimentary records will also be discussed.

A Review of the Effect of Dietary Composition on Fasting Substrate Oxidation in Healthy and Overweight Subjects.

PubMed

Whelan, Megan E; Wright, Olivia R L; Hickman, Ingrid J

2016-01-01

The purpose of this review was to assess existing evidence on the effects of chronic dietary macronutrient composition on substrate oxidation during a fasted state in healthy and overweight subjects. A systematic review of studies was conducted across five databases. Studies were included if they were English language studies of human adults, ≥19 years, used indirect calorimetry (ventilated hood technique), specified dietary macronutrient composition, and measured substrate oxidation. There was no evidence that variations of a typical, non-experimental diet influenced rate or ratio of substrate utilization, however there may be an upper and lower threshold for when macronutrient composition may directly alter preferences for fuel oxidation rates during a fasted state. This review indicates that macronutrient composition of a wide range of typical, non-experimental dietary fat and carbohydrate intakes has no effect on fasting substrate oxidation. This suggests that strict control of dietary intake prior to fasting indirect calorimetry measurements may be an unnecessary burden for study participants. Further research into the effects of long-term changes in isocaloric macronutrient shift is required.

Self-assembly of bimetallic AuxPd1-x alloy nanoparticles via dewetting of bilayers through the systematic control of temperature, thickness, composition and stacking sequence

NASA Astrophysics Data System (ADS)

Kunwar, Sundar; Pandey, Puran; Sui, Mao; Bastola, Sushil; Lee, Jihoon

2018-03-01

Bimetallic alloy nanoparticles (NPs) are attractive materials for various applications with their morphology and elemental composition dependent optical, electronic, magnetic and catalytic properties. This work demonstrates the evolution of AuxPd1-x alloy nanostructures by the solid-state dewetting of sequentially deposited bilayers of Au and Pd on sapphire (0001). Various shape, size and configuration of AuxPd1‑x alloy NPs are fabricated by the systematic control of annealing temperature, deposition thickness, composition as well as stacking sequence. The evolution of alloy nanostructures is attributed to the surface diffusion, interface diffusion between bilayers, surface and interface energy minimization, Volmer-Weber growth model and equilibrium configuration. Depending upon the temperature, the surface morphologies evolve with the formation of pits, grains and voids and gradually develop into isolated semi-spherical alloy NPs by the expansion of voids and agglomeration of Au and Pd adatoms. On the other hand, small isolated to enlarged elongated and over-grown layer-like alloy nanostructures are fabricated due to the coalescence, partial diffusion and inter-diffusion with the increased bilayer thickness. In addition, the composition and stacking sequence of bilayers remarkably affect the final geometry of AuxPd1‑x nanostructures due to the variation in the dewetting process. The optical analysis based on the UV–vis-NIR reflectance spectra reveals the surface morphology dependent plasmonic resonance, scattering, reflection and absorption properties of AuxPd1‑x alloy nanostructures.

Systematic analysis of the unique band gap modulation of mixed halide perovskites.

PubMed

Kim, Jongseob; Lee, Sung-Hoon; Chung, Choong-Heui; Hong, Ki-Ha

2016-02-14

Solar cells based on organic-inorganic hybrid metal halide perovskites have been proven to be one of the most promising candidates for the next generation thin film photovoltaic cells. Mixing Br or Cl into I-based perovskites has been frequently tried to enhance the cell efficiency and stability. One of the advantages of mixed halides is the modulation of band gap by controlling the composition of the incorporated halides. However, the reported band gap transition behavior has not been resolved yet. Here a theoretical model is presented to understand the electronic structure variation of metal mixed-halide perovskites through hybrid density functional theory. Comparative calculations in this work suggest that the band gap correction including spin-orbit interaction is essential to describe the band gap changes of mixed halides. In our model, both the lattice variation and the orbital interactions between metal and halides play key roles to determine band gap changes and band alignments of mixed halides. It is also presented that the band gap of mixed halide thin films can be significantly affected by the distribution of halide composition.

Gravity, Body Mass and Composition, and Metabolic Rate

NASA Technical Reports Server (NTRS)

Pace, N.; Smith, A. H.

1985-01-01

Metabolic rate and body composition as a function of sex and age were defined in 5 species of common laboratory mammals, the mouse, hamster, rat, guinea pig and rabbit. Oxygen consumption and carbon dioxide production rates were measured individually in 6 male and 6 female animals for each of 8 age cohorts ranging from 1 month to 2 years, and for each of the species. From the results it is evident that among these small mammals there is no indication of scaling of muscularity to body size, despite the 100-fold difference in body mass represented by the skeletal musculature seems to reach a pronounced peak value at age 2 to 3 months and then declines, the fraction of the fat-free body represented by other body components in older animals must increase complementarily. Under normal gravity conditions muscularity in small laboratory mammals displays large, systematic variation as a function both of species and age. This variation must be considered when such animals are subjects of experiments to study the effects of altered gravitational loading on the skeletal musculature of the mammal.

Chemical composition of axillary odorants reflects social and individual attributes in rhesus macaques.

PubMed

Weiß, Brigitte M; Kücklich, Marlen; Thomsen, Ruth; Henkel, Stefanie; Jänig, Susann; Kulik, Lars; Birkemeyer, Claudia; Widdig, Anja

2018-01-01

Scents play an important role in the life of most terrestrial mammals and may transmit valuable information about conspecifics. Olfaction was long considered of low importance in Old World monkeys due to their relative reduction of olfactory structures and low incidence of scent-marking behavior but has been increasingly recognized for mediating social relationships in recent years. Yet, studies investigating the composition of their chemical cues remain scarce. In the present study, we analyzed the potential information content of chemicals present on the skin of rhesus macaques ( Macaca mulatta ). We collected axillary secretions from 60 animals of the semifree-ranging population on Cayo Santiago (Puerto Rico, USA) with precleaned cotton swabs from which the secretions were subsequently extracted and analyzed by gas chromatography-mass spectrometry. Rhesus macaque axillary odorants varied in their overall similarity and composition. This variation was attributable to differences in sex, group membership, and kinship and further appeared to reflect age and rank in parts of our sample. The compounds most strongly associated with this variation primarily comprised larger molecular weight aldehydes and steroids. Such compounds are considered to be perceivable by the primate olfactory system through close-range interactions or through breakdown into smaller molecules by bacterial fermentation. Overall, our results provide additional evidence that odors of Old World monkeys reflect a wealth of potential information about their carrier, which provides the basis for chemical communication via body odors; however, its use by conspecifics needs to be confirmed in bioassays. One prerequisite for olfactory communication is the presence of systematic variation in animal odors that is related to attributes such as age, sex, or kinship. The composition of odors has been examined in numerous mammals but, with the exception of humans, remains poorly understood in Old World monkeys and apes, taxonomic groups in which most species do not show scent-marking behavior. In the present study, we show that the composition of axillary secretions of an Old World monkey, the rhesus macaque, reflects sex, group membership, relatedness, and possibly also age and rank. This variation thus provides a basis for olfactory communication in Old World monkeys.

Chemical variation and fractionation of KREEP basalt magmas

NASA Technical Reports Server (NTRS)

Irving, A. J.

1977-01-01

The fact that 53 Apollo 15 igneous KREEP basalts show a range of 100 Mg/(Mg + Fe) from 73 to 35, and that there are systematic variations in K2O and trace element abundances with the Mg/(Mg + Fe) ratio, suggests that the KREEP basalts are a magma series generated by fractional crystallization processes. Experimental and chemical evidence indicate that this magma series results from low-pressure, possibly subvolcanic, fractional crystallization of a magnesian parental liquid (100 Mg/(Mg + Fe) equal to approximately 72) by removal of low-Ca pyroxene and plagioclase, with eventual production of liquids similar in composition to 15405 quartz-monozodiorites. One soil sample, SAO 465-11, corresponds to the postulated parental liquid, which might have been a direct partial melt of troctolitic materials in the deep lunar crust.

Osmium isotope variations in the oceans recorded by Fe-Mn crusts

USGS Publications Warehouse

Burton, K.W.; Bourdon, B.; Birck, J.-L.; Allegre, C.J.; Hein, J.R.

1999-01-01

This study presents osmium (Os) isotope data for recent growth surfaces of hydrogenetic ferromanganese (Fe-Mn) crusts from the Pacific, Atlantic and Indian Oceans. In general, these data indicate a relatively uniform Os isotopic composition for modern seawater, but suggest that North Atlantic seawater is slightly more radiogenic than that of the Pacific and Indian Oceans. The systematic difference in the Os isotopic composition between the major oceans probably reflects a greater input of old continental material with a high Re/Os ratio in the North Atlantic Ocean, consistent with the distribution of Nd and Pb isotopes. This spatial variation in the Os isotope composition in seawater is consistent with a residence time for Os of between 2 and 60 kyr. Indian Ocean samples show no evidence of a local source of radiogenic Os, which suggests that the present-day riverine input from the Himalaya-Tibet region is not a major source for Os. Recently formed Fe-Mn crusts from the TAG hydrothermal field in the North Atlantic yield an Os isotopic composition close to that of modern seawater, which indicates that, in this area, the input of unradiogenic Os from the hydrothermal alteration of oceanic crust is small. However, some samples from the deep Pacific (???4 km) possess a remarkably unradiogenic Os isotope composition (187Os/186Os ratios as low as 4.3). The compositional control of Os incorporation into the crusts and mixing relationships suggest that this unradiogenic composition is most likely due to the direct incorporation of micrometeoritic or abyssal peridotite particles, rather than indicating the presence of an unradiogenic deep-water mass. Moreover, this unradiogenic signal appears to be temporary, and local, and has had little apparent effect on the overall evolution of seawater. These results confirm that input of continental material through erosion is the dominant source of Os in seawater, but it is not clear whether global Os variations are due to the input of mantle or meteoritic material, or simply indicate that the continental source itself is not uniform.

Tuning the dielectric properties of metallic-nanoparticle/elastomer composites by strain.

PubMed

Gaiser, Patrick; Binz, Jonas; Gompf, Bruno; Berrier, Audrey; Dressel, Martin

2015-03-14

Tunable metal/dielectric composites are promising candidates for a large number of potential applications in electronics, sensor technologies and optical devices. Here we systematically investigate the dielectric properties of Ag-nanoparticles embedded in the highly flexible elastomer poly-dimethylsiloxane (PDMS). As tuning parameter we use uniaxial and biaxial strain applied to the composite. We demonstrate that both static variations of the filling factor and applied strain lead to the same behavior, i.e., the filling factor of the composite can be tuned by application of strain. In this way the effective static permittivity εeff of the composite can be varied over a very large range. Once the Poisson's ratio of the composite is known, the strain dependent dielectric constant can be accurately described by effective medium theory without any additional free fit parameter up to metal filling factors close to the percolation threshold. It is demonstrated that, starting above the percolation threshold in the metallic phase, applying strain provides the possibility to cross the percolation threshold into the insulating region. The change of regime from conductive phase down to insulating follows the description given by percolation theory and can be actively controlled.

The Preparation and Characterization of INTEC HAW Phase I Composition Variation Study Glasses

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

Musick, C. A.; Peeler, D. K.; Piepel, G. F.

1999-03-01

A glass composition variation study (CVS) is in progress to define formulations for the vitrification of high activity waste (HAW) proposed to be separated from dissolved calcine stored at the Idaho National Engineering and Environmental Laboratory (INEEL). Estimates of calcine and HAW compositions prepared in FY97 were used to define test matrix glasses. The HAW composition is of particular interest because high aluminum, zirconium, phosphorous and potassium, and low iron and sodium content places it outside the realm of vitrification experience in the Department of Energy (DOE) complex. Through application of statistical techniques, a test matrix was defined for Phasemore » 1 of the CVS. From this matrix, formulations were systematically selected for preparation and characterization with respect to homogeneity, viscosity, liquidus temperature (TL), and leaching response when subjected to the Product Consistency Test (PCT). Based on the properties determined, certain formulations appear suitable for further development including use in planning Phase 2 of the study. It is recommended that glasses to be investigated in Phase 2 be limited to 3-5 wt % phosphate. The results of characterizing the Phase 1 glasses are presented in this document. A full analysis of the composition-property relationships of glasses being developed for immobilizing HAWs will be performing at the completion of CVS phases. This analysis will be needed for the optimization of the glass formulations of vitrifying HAW. Contributions were made to this document by personnel working at the INEEL, Pacific Northwest National Laboratories (PNNL), and the Savannah River Technology Center (SRTC).« less

Barium isotopes reveal role of ocean circulation on barium cycling in the Atlantic

NASA Astrophysics Data System (ADS)

Bates, Stephanie L.; Hendry, Katharine R.; Pryer, Helena V.; Kinsley, Christopher W.; Pyle, Kimberley M.; Woodward, E. Malcolm S.; Horner, Tristan J.

2017-05-01

We diagnose the relative influences of local-scale biogeochemical cycling and regional-scale ocean circulation on Atlantic barium cycling by analysing four new depth profiles of dissolved Ba concentrations and isotope compositions from the South and tropical North Atlantic. These new profiles exhibit systematic vertical, zonal and meridional variations that reflect the influence of both local-scale barite cycling and large-scale ocean circulation. Epipelagic decoupling of dissolved Ba and Si reported previously in the tropics is also found to be associated with significant Ba isotope heterogeneity. As such, we contend that this decoupling originates from the depth segregation of opal and barite formation but is exacerbated by weak vertical mixing. Zonal influence from isotopically-'heavy' water masses in the western North Atlantic evidence the advective inflow of Ba-depleted Upper Labrador Sea Water, which is not seen in the eastern basin or the South Atlantic. Meridional variations in Atlantic Ba isotope systematics below 2000 m appear entirely controlled by conservative mixing. Using an inverse isotopic mixing model, we calculate the Ba isotope composition of the Ba-poor northern end-member as +0.45 ‰ and the Ba-rich southern end-member +0.26 ‰, relative to NIST SRM 3104a. The near-conservative behaviour of Ba below 2000 m indicates that Ba isotopes can serve as an independent tracer of the provenance of northern- versus southern-sourced water masses in the deep Atlantic Ocean. This finding may prove useful in palaeoceanographic studies, should appropriate sedimentary archives be identified, and offers new insights into the processes that cycle Ba in seawater.

Systematic Experimental Designs For Mixed-species Plantings

Treesearch

Jeffery C. Goelz

2001-01-01

Systematic experimental designs provide splendid demonstration areas for scientists and land managers to observe the effects of a gradient of species composition. Systematic designs are based on large plots where species composition varies gradually. Systematic designs save considerable space and require many fewer seedlings than conventional mixture designs. One basic...

Thermodynamic and kinetic modeling of Mn-Ni-Si precipitates in low-Cu reactor pressure vessel steels

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

Ke, Huibin; Wells, Peter; Edmondson, Philip D.

Formation of large volume fractions of Mn-Ni-Si precipitates (MNSPs) causes excess irradiation embrittlement of reactor pressure vessel (RPV) steels at high, extended-life fluences. Thus, a new and unique, semi-empirical cluster dynamics model was developed to study the evolution of MNSPs in low-Cu RPV steels. The model is based on CALPHAD thermodynamics and radiation enhanced diffusion kinetics. The thermodynamics dictates the compositional and temperature dependence of the free energy reductions that drive precipitation. The model treats both homogeneous and heterogeneous nucleation, where the latter occurs on cascade damage, like dislocation loops. The model has only four adjustable parameters that were fitmore » to an atom probe tomography (APT) database. The model predictions are in semi-quantitative agreement with systematic Mn, Ni and Si composition variations in alloys characterized by APT, including a sensitivity to local tip-to-tip variations even in the same steel. The model predicts that heterogeneous nucleation plays a critical role in MNSP formation in lower alloy Ni contents. Single variable assessments of compositional effects show that Ni plays a dominant role, while even small variations in irradiation temperature can have a large effect on the MNSP evolution. Within typical RPV steel ranges, Mn and Si have smaller effects. Furthermore, the delayed but then rapid growth of MNSPs to large volume fractions at high fluence is well predicted by the model. For purposes of illustration, the effect of MNSPs on transition temperature shifts are presented based on well-established microstructure-property and property-property models.« less

Thermodynamic and kinetic modeling of Mn-Ni-Si precipitates in low-Cu reactor pressure vessel steels

DOE PAGES

Ke, Huibin; Wells, Peter; Edmondson, Philip D.; ...

2017-07-12

Formation of large volume fractions of Mn-Ni-Si precipitates (MNSPs) causes excess irradiation embrittlement of reactor pressure vessel (RPV) steels at high, extended-life fluences. Thus, a new and unique, semi-empirical cluster dynamics model was developed to study the evolution of MNSPs in low-Cu RPV steels. The model is based on CALPHAD thermodynamics and radiation enhanced diffusion kinetics. The thermodynamics dictates the compositional and temperature dependence of the free energy reductions that drive precipitation. The model treats both homogeneous and heterogeneous nucleation, where the latter occurs on cascade damage, like dislocation loops. The model has only four adjustable parameters that were fitmore » to an atom probe tomography (APT) database. The model predictions are in semi-quantitative agreement with systematic Mn, Ni and Si composition variations in alloys characterized by APT, including a sensitivity to local tip-to-tip variations even in the same steel. The model predicts that heterogeneous nucleation plays a critical role in MNSP formation in lower alloy Ni contents. Single variable assessments of compositional effects show that Ni plays a dominant role, while even small variations in irradiation temperature can have a large effect on the MNSP evolution. Within typical RPV steel ranges, Mn and Si have smaller effects. Furthermore, the delayed but then rapid growth of MNSPs to large volume fractions at high fluence is well predicted by the model. For purposes of illustration, the effect of MNSPs on transition temperature shifts are presented based on well-established microstructure-property and property-property models.« less

Compositional variations and differential diagenesis in Miocene turbidites from the western coast of Mallorca (Balearic Islands, Spain)

NASA Astrophysics Data System (ADS)

Felder, Sonja; Westphal, Hildegard; Munnecke, Axel; Mateu Vicens, Guillem

2010-05-01

Compositional variations and differential diagenesis in Miocene turbidites from the western coast of Mallorca (Balearic Islands, Spain) Sonja Felder (1), Hildegard Westphal (1), Axel Munnecke (2), Guillem Mateu Vicens (1,3) (1) MARUM and Department of Geosciences, Universität Bremen, Leobener Straße, 28359 Bremen, Germany (2) GeoZentrum Nordbayern, Universität Erlangen-Nürnberg, Loewenichstr. 28, 91054 Erlangen, Germany (3) Dipartimento di Scienze della Terra, Università di Roma "La Sapienza", Ple Aldo 7 Moro, 5. I-00185 Roma, Italy Cyclic alternations of limestone and marl beds crop out along the western coast of the Island of Mallorca. This Miocene succession is traditionally interpreted to represent more weathering-resistant turbidites interlayered by softer hemipelagic background sediment. However, the cementation patterns that dominate the appearance of the outcrop do not always consistently follow sedimentary layering; locally the cemented beds are systematically oblique to the sedimentary layers. Compositional studies demonstrate that differences in non-carbonate fraction, carbonate concentration and fossil content (e.g. foraminiferal assemblages) trace sedimentary bedding, regardless the diagenetic style. Limestone versus marl lithology, in contrast, is defined by the diagenetic style, tight cementation by calcite cements in the limestones versus low porosity and compaction in the marls. The reason for this striking pattern of diagenetic bedding cross-cutting sedimentary layers is assumed to be related to tectonic fracturing, opening pathways for diagenetic fluids. This example cautions the straight-forward interpretation of limestone-marl alternations as direct witnesses of environmental or climatic variations.

Variation across mitochondrial gene trees provides evidence for systematic error: How much gene tree variation is biological?

PubMed

Richards, Emilie J; Brown, Jeremy M; Barley, Anthony J; Chong, Rebecca A; Thomson, Robert C

2018-02-19

The use of large genomic datasets in phylogenetics has highlighted extensive topological variation across genes. Much of this discordance is assumed to result from biological processes. However, variation among gene trees can also be a consequence of systematic error driven by poor model fit, and the relative importance of biological versus methodological factors in explaining gene tree variation is a major unresolved question. Using mitochondrial genomes to control for biological causes of gene tree variation, we estimate the extent of gene tree discordance driven by systematic error and employ posterior prediction to highlight the role of model fit in producing this discordance. We find that the amount of discordance among mitochondrial gene trees is similar to the amount of discordance found in other studies that assume only biological causes of variation. This similarity suggests that the role of systematic error in generating gene tree variation is underappreciated and critical evaluation of fit between assumed models and the data used for inference is important for the resolution of unresolved phylogenetic questions.

Contrasting spatial patterns and ecological attributes of soil bacterial and archaeal taxa across a landscape.

PubMed

Constancias, Florentin; Saby, Nicolas P A; Terrat, Sébastien; Dequiedt, Samuel; Horrigue, Wallid; Nowak, Virginie; Guillemin, Jean-Philippe; Biju-Duval, Luc; Chemidlin Prévost-Bouré, Nicolas; Ranjard, Lionel

2015-06-01

Even though recent studies have clarified the influence and hierarchy of environmental filters on bacterial community structure, those constraining bacterial populations variations remain unclear. In consequence, our ability to understand to ecological attributes of soil bacteria and to predict microbial community response to environmental stress is therefore limited. Here, we characterized the bacterial community composition and the various bacterial taxonomic groups constituting the community across an agricultural landscape of 12 km(2) , by using a 215 × 215 m systematic grid representing 278 sites to precisely decipher their spatial distribution and drivers at this scale. The bacterial and Archaeal community composition was characterized by applying 16S rRNA gene pyrosequencing directly to soil DNA from samples. Geostatistics tools were used to reveal the heterogeneous distribution of bacterial composition at this scale. Soil physical parameters and land management explained a significant amount of variation, suggesting that environmental selection is the major process shaping bacterial composition. All taxa systematically displayed also a heterogeneous and particular distribution patterns. Different relative influences of soil characteristics, land use and space were observed, depending on the taxa, implying that selection and spatial processes might be differentially but not exclusively involved for each bacterial phylum. Soil pH was a major factor determining the distribution of most of the bacterial taxa and especially the most important factor explaining the spatial patterns of α-Proteobacteria and Planctomycetes. Soil texture, organic carbon content and quality were more specific to a few number of taxa (e.g., β-Proteobacteria and Chlorobi). Land management also influenced the distribution of bacterial taxa across the landscape and revealed different type of response to cropping intensity (positive, negative, neutral or hump-backed relationships) according to phyla. Altogether, this study provided valuable clues about the ecological behavior of soil bacterial and archaeal taxa at an agricultural landscape scale and could be useful for developing sustainable strategies of land management. © 2015 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

A palaeotemperature curve for the Precambrian oceans based on silicon isotopes in cherts.

PubMed

Robert, François; Chaussidon, Marc

2006-10-26

The terrestrial sediment record indicates that the Earth's climate varied drastically in the Precambrian era (before 550 million years ago), ranging from surface temperatures similar to or higher than today's to global glaciation events. The most continuous record of sea surface temperatures of that time has been derived from variations in oxygen isotope ratios of cherts (siliceous sediments), but the long-term cooling of the oceans inferred from those data has been questioned because the oxygen isotope signature could have been reset through the exchange with hydrothermal fluids after deposition of the sediments. Here we show that the silicon isotopic composition of cherts more than 550 million years old shows systematic variations with age that support the earlier conclusion of long-term ocean cooling and exclude post-depositional exchange as the main source of the isotopic variations. In agreement with other lines of evidence, a model of the silicon cycle in the Precambrian era shows that the observed silicon isotope variations imply seawater temperature changes from about 70 degrees C 3,500 million years ago to about 20 degrees C 800 million years ago.

Early Results from the Lunar Atmosphere and Dust Environment Explorer (LADEE)

NASA Technical Reports Server (NTRS)

Elphic, R. C.; Hine, B.; Delory, G. T.; Mahaffy, Paul; Benna, Mehdi; Horanyi, Mihaly; Colaprete, Anthony; Noble, Sarah

2014-01-01

On 6 September, 2013, a near-perfect launch of the first Minotaur V rocket successfully carried NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) into a high-eccentricity geocentric orbit. After 30 days of phasing, LADEE arrived at the Moon on 6 October, 2013. LADEE's science objectives are twofold: (1) Determine the composition of the lunar atmosphere, investigate processes controlling its distribution and variability, including sources, sinks, and surface interactions; (2) Characterize the lunar exospheric dust environment, measure its spatial and temporal variability, and effects on the lunar atmosphere, if any. After a successful commissioning phase, the three science instruments have made systematic observations of the lunar dust and exospheric environment. These include initial observations of argon, neon and helium exospheres, and their diurnal variations; the lunar micrometeoroid impact ejecta cloud and its variations; spatial and temporal variations of the sodium exosphere; and the search for sunlight extinction caused by dust. LADEE also made observations of the effects of the Chang'e 3 landing on 14 December 2013.

Oxygen Isotope Measurements of a Rare Murchison Type A CAI and Its Rim

NASA Technical Reports Server (NTRS)

Matzel, J. E. P.; Simon, J. I.; Hutcheon, I. D.; Jacobsen, B.; Simon, S. B.; Grossman, L.

2013-01-01

Ca-, Al-rich inclusions (CAIs) from CV chondrites commonly show oxygen isotope heterogeneity among different mineral phases within individual inclusions reflecting the complex history of CAIs in both the solar nebula and/or parent bodies. The degree of isotopic exchange is typically mineral-specific, yielding O-16-rich spinel, hibonite and pyroxene and O-16-depleted melilite and anorthite. Recent work demonstrated large and systematic variations in oxygen isotope composition within the margin and Wark-Lovering rim of an Allende Type A CAI. These variations suggest that some CV CAIs formed from several oxygen reservoirs and may reflect transport between distinct regions of the solar nebula or varying gas composition near the proto-Sun. Oxygen isotope compositions of CAIs from other, less-altered chondrites show less intra-CAI variability and 16O-rich compositions. The record of intra-CAI oxygen isotope variability in CM chondrites, which commonly show evidence for low-temperature aqueous alteration, is less clear, in part because the most common CAIs found in CM chondrites are mineralogically simple (hibonite +/- spinel or spinel +/- pyroxene) and are composed of minerals less susceptible to O-isotopic exchange. No measurements of the oxygen isotope compositions of rims on CAIs in CM chondrites have been reported. Here, we present oxygen isotope data from a rare, Type A CAI from the Murchison meteorite, MUM-1. The data were collected from melilite, hibonite, perovskite and spinel in a traverse into the interior of the CAI and from pyroxene, melilite, anorthite, and spinel in the Wark-Lovering rim. Our objectives were to (1) document any evidence for intra-CAI oxygen isotope variability; (2) determine the isotopic composition of the rim minerals and compare their composition(s) to the CAI interior; and (3) compare the MUM-1 data to oxygen isotope zoning profiles measured from CAIs in other chondrites.

Along and across arc geochemical variations in NW Central America: Evidence for involvement of lithospheric pyroxenite

NASA Astrophysics Data System (ADS)

Heydolph, Ken; Hoernle, Kaj; Hauff, Folkmar; Bogaard, Paul van den; Portnyagin, Maxim; Bindeman, Ilya; Garbe-Schönberg, Dieter

2012-05-01

The Central American Volcanic Arc (CAVA) has been the subject of intensive research over the past few years, leading to a variety of distinct models for the origin of CAVA lavas with various source components. We present a new model for the NW Central American Volcanic Arc based on a comprehensive new geochemical data set (major and trace element and Sr-Nd-Pb-Hf-O isotope ratios) of mafic volcanic front (VF), behind the volcanic front (BVF) and back-arc (BA) lava and tephra samples from NW Nicaragua, Honduras, El Salvador and Guatemala. Additionally we present data on subducting Cocos Plate sediments (from DSDP Leg 67 Sites 495 and 499) and igneous oceanic crust (from DSDP Leg 67 Site 495), and Guatemalan (Chortis Block) granitic and metamorphic continental basement. We observe systematic variations in trace element and isotopic compositions both along and across the arc. The data require at least three different endmembers for the volcanism in NW Central America. (1) The NW Nicaragua VF lavas require an endmember with very high Ba/(La, Th) and U/Th, relatively radiogenic Sr, Nd and Hf but unradiogenic Pb and low δ18O, reflecting a largely serpentinite-derived fluid/hydrous melt flux from the subducting slab into a depleted N-MORB type of mantle wedge. (2) The Guatemala VF and BVF mafic lavas require an enriched endmember with low Ba/(La, Th), U/Th, high δ18O and radiogenic Sr and Pb but unradiogenic Nd and Hf isotope ratios. Correlations of Hf with both Nd and Pb isotopic compositions are not consistent with this endmember being subducted sediments. Granitic samples from the Chiquimula Plutonic Complex in Guatemala have the appropriate isotopic composition to serve as this endmember, but the large amounts of assimilation required to explain the isotope data are not consistent with the basaltic compositions of the volcanic rocks. In addition, mixing regressions on Nd vs. Hf and the Sr and O isotope plots do not go through the data. Therefore, we propose that this endmember could represent pyroxenites in the lithosphere (mantle and possibly lower crust), derived from parental magmas for the plutonic rocks. (3) The Honduras and Caribbean BA lavas define an isotopically depleted endmember (with unradiogenic Sr but radiogenic Nd, Hf and Pb isotope ratios), having OIB-like major and trace element compositions (e.g. low Ba/(La, Th) and U/Th, high La/Yb). This endmember is possibly derived from melting of young, recycled oceanic crust in the asthenosphere upwelling in the back-arc. Mixing between these three endmember types of magmas can explain the observed systematic geochemical variations along and across the NW Central American Arc.

The May 2003 eruption of Anatahan volcano, Mariana Islands: Geochemical evolution of a silicic island-arc volcano

USGS Publications Warehouse

Wade, J.A.; Plank, T.; Stern, R.J.; Tollstrup, D.L.; Gill, J.B.; O'Leary, J. C.; Eiler, J.M.; Moore, R.B.; Woodhead, J.D.; Trusdell, F.; Fischer, T.P.; Hilton, David R.

2005-01-01

The first historical eruption of Anatahan volcano began on May 10, 2003. Samples of tephra from early in the eruption were analyzed for major and trace elements, and Sr, Nd, Pb, Hf, and O isotopic compositions. The compositions of these tephras are compared with those of prehistoric samples of basalt and andesite, also newly reported here. The May 2003 eruptives are medium-K andesites with 59-63 wt.% SiO2, and are otherwise homogeneous (varying less than 3% 2?? about the mean for 45 elements). Small, but systematic, chemical differences exist between dark (scoria) and light (pumice) fragments, which indicate fewer mafic and oxide phenocrysts in, and less degassing for, the pumice than scoria. The May 2003 magmas are nearly identical to other prehistoric eruptives from Anatahan. Nonetheless, Anatahan has erupted a wide range of compositions in the past, from basalt to dacite (49-66 wt.% SiO2). The large proportion of lavas with silicic compositions at Anatahan (> 59 wt.% SiO2) is unique within the active Mariana Islands, which otherwise erupt a narrow range of basalts and basaltic andesites. The silicic compositions raise the question of whether they formed via crystal fractionation or crustal assimilation. The lack of 87Sr/86Sr variation with silica content, the MORB-like ??18O, and the incompatible behavior of Zr rule out assimilation of old crust, altered crust, or zircon-saturated crustal melts, respectively. Instead, the constancy of isotopic and trace element ratios, and the systematic variations in REE patterns are consistent with evolution by crystal fractionation of similar parental magmas. Thus, Anatahan is a type example of an island-arc volcano that erupts comagmatic basalts to dacites, with no evidence for crustal assimilation. The parental magmas to Anatahan lie at the low 143Nd/144Nd, Ba/La, and Sm/La end of the spectrum of magmas erupted in the Marianas arc, consistent with 1-3 wt.% addition of subducted sediment to the mantle source, or roughly one third of the sedimentary column. The high Th/La in Anatahan magmas is consistent with shallow loss of the top 50 m of the sedimentary column during subduction. ?? 2005 Elsevier B.V. All rights reserved.

Validation of a sampling plan to generate food composition data.

PubMed

Sammán, N C; Gimenez, M A; Bassett, N; Lobo, M O; Marcoleri, M E

2016-02-15

A methodology to develop systematic plans for food sampling was proposed. Long life whole and skimmed milk, and sunflower oil were selected to validate the methodology in Argentina. Fatty acid profile in all foods, proximal composition, and calcium's content in milk were determined with AOAC methods. The number of samples (n) was calculated applying Cochran's formula with variation coefficients ⩽12% and an estimate error (r) maximum permissible ⩽5% for calcium content in milks and unsaturated fatty acids in oil. n were 9, 11 and 21 for long life whole and skimmed milk, and sunflower oil respectively. Sample units were randomly collected from production sites and sent to labs. Calculated r with experimental data was ⩽10%, indicating high accuracy in the determination of analyte content of greater variability and reliability of the proposed sampling plan. The methodology is an adequate and useful tool to develop sampling plans for food composition analysis. Copyright © 2015 Elsevier Ltd. All rights reserved.

Systematics of the CHON and other light-element particle populations in Comet Halley

NASA Technical Reports Server (NTRS)

Clark, Benton; Mason, Larry W.; Kissel, Jochen

1986-01-01

Based on chemical signatures measured by the PIA experiment during the Giotto flyby of comet Halley, particle classifications were designated. In addition to silicate-like grains and particles of mixed (cosmic) composition, there appear to be several light-element rich populations, including the CHON, (H,C), (H,C,O), and (H,C,N) particle types. These compositional classes are further distinguished by differences in mass distributions, a density indicator, and variations in relative abundance within the coma. These particle populations are evidence for chemical heterogeneity in the surface of the cometary nucleus. Particles found mainly in the inner coma may be volatile icy grains. Most of the N of the comet may be found in up to three different populations of grains; one or more of these may be responsible for the observation of cyanojets.

Petrology of basaltic sills from ocean drilling program sites 794 and 797 in the Yamato Basin of the Japan Sea

NASA Technical Reports Server (NTRS)

Thy, P.

1992-01-01

The basaltic sills from ocean drilling program sites 794 and 797 in the Yamato Basin of the Japan Sea are characterized petrographically on the basis of a detailed study of the composition of relict phenocryst and groundmass phases. The systematic variation in the rock compositions is discussed. Results of 1-atm melting experiments on a relatively primitive basalt from site 797 are reported. The sills are found to constitute two distinct groups of suites: primitive, olivine-bearing suites with low potassium and primitive olivine-bearing to evolved, olivine-free suites with relatively high potassium. A pseudoinvariant reaction relationship between olivine and augite and magnetite is inferred. Complex magmatic and tectonic evolutions in the region, perhaps reflecting a transitional stage between subduction zone activity and back arc spreading, are suggested.

The Surtsey Magma Series.

PubMed

Schipper, C Ian; Jakobsson, Sveinn P; White, James D L; Michael Palin, J; Bush-Marcinowski, Tim

2015-06-26

The volcanic island of Surtsey (Vestmannaeyjar, Iceland) is the product of a 3.5-year-long eruption that began in November 1963. Observations of magma-water interaction during pyroclastic episodes made Surtsey the type example of shallow-to-emergent phreatomagmatic eruptions. Here, in part to mark the 50(th) anniversary of this canonical eruption, we present previously unpublished major-element whole-rock compositions, and new major and trace-element compositions of sideromelane glasses in tephra collected by observers and retrieved from the 1979 drill core. Compositions became progressively more primitive as the eruption progressed, with abrupt changes corresponding to shifts between the eruption's four edifices. Trace-element ratios indicate that the chemical variation is best explained by mixing of different proportions of depleted ridge-like basalt, with ponded, enriched alkalic basalt similar to that of Iceland's Eastern Volcanic Zone; however, the systematic offset of Surtsey compositions to lower Nb/Zr than other Vestmannaeyjar lavas indicates that these mixing end members are as-yet poorly contained by compositions in the literature. As the southwestern-most volcano in the Vestmannaeyjar, the geochemistry of the Surtsey Magma Series exemplifies processes occurring within ephemeral magma bodies on the extreme leading edge of a propagating off-axis rift in the vicinity of the Iceland plume.

Modeling Systematicity and Individuality in Nonlinear Second Language Development: The Case of English Grammatical Morphemes

ERIC Educational Resources Information Center

Murakami, Akira

2016-01-01

This article introduces two sophisticated statistical modeling techniques that allow researchers to analyze systematicity, individual variation, and nonlinearity in second language (L2) development. Generalized linear mixed-effects models can be used to quantify individual variation and examine systematic effects simultaneously, and generalized…

The association between neighbourhoods and educational achievement, a systematic review and meta-analysis.

PubMed

Nieuwenhuis, Jaap; Hooimeijer, Pieter

2016-01-01

Many studies have examined the effects of neighbourhoods on educational outcomes. The results of these studies are often conflicting, even if the same independent variables (such as poverty, educational climate, social disorganisation, or ethnic composition) are used. A systematic meta-analysis may help to resolve this lack of external validity. We identified 5516 articles from which we selected 88 that met all of the inclusion criteria. Using meta-regression, we found that the relation between neighbourhoods and individual educational outcomes is a function of neighbourhood poverty, the neighbourhood's educational climate, the proportion of ethnic/migrant groups, and social disorganisation in the neighbourhood. The variance in the findings from different studies can partly be explained by the sampling design and the type of model used in each study. More important is the use of control variables (school, family SES, and parenting variables) in explaining the variation in the strength of neighbourhood effects.

Does Oxygen Isotopic Heterogeneity in Refractory Inclusions and Their Wark-Lovering Rims Record Nebular Repressing?

NASA Technical Reports Server (NTRS)

Simon, J. I.; Matzel, J. E. P.; Simon, S. B.; Weber, P. K.; Grossman, L.; Ross, D. K.; Hutcheon, I. D.

2013-01-01

Large systematic variations in O-isotopic compositions found within individual mineral layers of rims surrounding Ca-, Al-rich inclusions (CAIs) and at the margins of some CAIs imply formation from distinct environments [e.g., 1-3]. The O-isotope compositions of many CAIs preserve a record of the Solar nebula gas believed to initially be O-16-rich (delta O-17 less than or equal to -25%0) [4-5]. Data from a recent study of the compact Type A Allende CAI, A37, preserve a diffusion profile in the outermost 70 micrometers of the inclusion and show greater than 25%0 variations in delta O-17 within its 100 micrometer-thick Wark-Lovering rim (WL-rim) [3]. This and comparable heterogeneity measured in several other CAIs have been explained by isotopic mixing between the O-16-rich Solar reservoir and a second O-16-poor reservoir (probably nebular gas) with a planetary-like isotopic composition, e.g., [1,2,3,6]. However, there is mineralogical and isotopic evidence from the interiors of CAIs, in particular those from Allende, for parent body alteration. At issue is how to distinguish the record of secondary reprocessing in the nebula from that which occurred on the parent body. We have undertaken the task to study a range of CAI types with varying mineralogies, in part, to address this problem.

PROBING X-RAY ABSORPTION AND OPTICAL EXTINCTION IN THE INTERSTELLAR MEDIUM USING CHANDRA OBSERVATIONS OF SUPERNOVA REMNANTS

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

Foight, Dillon R.; Slane, Patrick O.; Güver, Tolga

We present a comprehensive study of interstellar X-ray extinction using the extensive Chandra supernova remnant (SNR) archive and use our results to refine the empirical relation between the hydrogen column density and optical extinction. In our analysis, we make use of the large, uniform data sample to assess various systematic uncertainties in the measurement of the interstellar X-ray absorption. Specifically, we address systematic uncertainties that originate from (i) the emission models used to fit SNR spectra; (ii) the spatial variations within individual remnants; (iii) the physical conditions of the remnant such as composition, temperature, and non-equilibrium regions; and (iv) themore » model used for the absorption of X-rays in the interstellar medium. Using a Bayesian framework to quantify these systematic uncertainties, and combining the resulting hydrogen column density measurements with the measurements of optical extinction toward the same remnants, we find the empirical relation N {sub H} = (2.87 ± 0.12) × 10{sup 21} A {sub V} cm{sup 2}, which is significantly higher than the previous measurements.« less

The interaction between nitrogen and phosphorous is a strong predictor of intra-plant variation in nitrogen isotope composition in a desert species

DOE PAGES

Zhang, Jinxin; Gu, Lianhong; Zhang, Jingbo; ...

2017-01-11

Understanding intra-plant variations in δ 15N is essential for fully utilizing the potential of δ 15N as an integrator of the terrestrial nitrogen (N) cycle and as an indicator of the relative limitation of N and phosphorous (P) on plant growth. Studying such variations can also yield insights into N metabolism by plant as a whole or by specific organs. However, few researchers have systematically evaluated intra-plant variations in δ 15N and their relationships with organ nutrient contents. We excavated whole plant architectures of Nitraria tangutorum Bobrov, a C 3 species of vital regional ecological importance, in two deserts inmore » northwestern China. We systematically and simultaneously measured N isotope ratios and N and P contents of different parts of the excavated plants. We found that intra-plant variations in δ 15N of N. tangutorum were positively correlated with corresponding organ N and P contents. However, it was the N × P interaction, not N and P individually or their linear combination, that was the strongest predictor of intra-plant δ 15N. Additionally, we showed that root δ 15N increased with depth into soil, a pattern similar to profiles of soil δ 15N reported by previous studies in different ecosystems. We hypothesized that the strong positive intra-plant δ 15N–N and P relationships are caused by three processes acting in conjunction: (1) N and P content-driven fractionating exchanges of ammonia between leaves and the atmosphere (volatilization) during photorespiration, (2) resorption and remobilization of N and P from senescing leaves, and (3) mixture of the re-translocated foliar N and P with existing pools in stems and roots. To test our hypothesis, future studies should investigate plant N volatilization and associated isotope fractionation and intra-plant variations in δ 15N in different species across ecosystems and climates.« less

The interaction between nitrogen and phosphorous is a strong predictor of intra-plant variation in nitrogen isotope composition in a desert species

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

Zhang, Jinxin; Gu, Lianhong; Zhang, Jingbo

Understanding intra-plant variations in δ 15N is essential for fully utilizing the potential of δ 15N as an integrator of the terrestrial nitrogen (N) cycle and as an indicator of the relative limitation of N and phosphorous (P) on plant growth. Studying such variations can also yield insights into N metabolism by plant as a whole or by specific organs. However, few researchers have systematically evaluated intra-plant variations in δ 15N and their relationships with organ nutrient contents. We excavated whole plant architectures of Nitraria tangutorum Bobrov, a C 3 species of vital regional ecological importance, in two deserts inmore » northwestern China. We systematically and simultaneously measured N isotope ratios and N and P contents of different parts of the excavated plants. We found that intra-plant variations in δ 15N of N. tangutorum were positively correlated with corresponding organ N and P contents. However, it was the N × P interaction, not N and P individually or their linear combination, that was the strongest predictor of intra-plant δ 15N. Additionally, we showed that root δ 15N increased with depth into soil, a pattern similar to profiles of soil δ 15N reported by previous studies in different ecosystems. We hypothesized that the strong positive intra-plant δ 15N–N and P relationships are caused by three processes acting in conjunction: (1) N and P content-driven fractionating exchanges of ammonia between leaves and the atmosphere (volatilization) during photorespiration, (2) resorption and remobilization of N and P from senescing leaves, and (3) mixture of the re-translocated foliar N and P with existing pools in stems and roots. To test our hypothesis, future studies should investigate plant N volatilization and associated isotope fractionation and intra-plant variations in δ 15N in different species across ecosystems and climates.« less

Variations of the relative abundances of He, (C,N,O) and Fe-group nuclei in solar cosmic rays and their relationship to solar particle acceleration

NASA Technical Reports Server (NTRS)

Bertsch, D. L.; Biswas, S.; Fichtel, C. E.; Pellerin, C. J.; Reames, D. V.

1973-01-01

Measurements of the flux of helium nuclei in the 24 January 1971 event and of helium and (C,N,O) nuclei in the 1 September 1971 event are combined with previous measurements to obtain the relative abundances of helium, (C,N,O), and Fe-group nuclei in these events. These data are then summarized together with previously reported results to show that, even when the same detector system using a dE/dx plus range technique is used, differences in the He/(C,N,O) value in the same energy/nucleon interval are observed in solar cosmic ray events. Further, when the He/(C,N,O) value is lower the He/(Fe-group nuclei) value is also systematically lower in these large events. When solar particle acceleration theory is analyzed, it is seen that the results suggest that, for large events, Coulomb energy loss probably does not play a major role in determining solar particle composition at higher energies (10 MeV). The variations in multicharged nuclei composition are more likely due to partial ionization during the acceleration phase.

Geochemical and Isotopic Data from Micron to Across-Arc Scales in the Andean Central Volcanic Zone: Applications for Resolving Crustal Magmatic Differentiation and Modification Processes

NASA Astrophysics Data System (ADS)

Michelfelder, G.; Wilder, A.; Feeley, T.

2014-12-01

Plagioclase crystals from silicic (andesitic to dacitic) lavas and domes at Volcán Uturuncu, a potentially active volcano in the back-arc of the Andean CVZ (22.3°S, 67.2°W), exhibit large variations in An contents, textures, and core to rim 87Sr/86Sr ratios. Many of the isotopic variations can not have existed at magmatic temperatures for more than a few thousand years. The crystals likely derived from different locations in the crustal magmatic system and mixed just prior to eruption. Uturuncu magmas initially assimilated crustal rocks with high 87Sr/86Sr ratios. The magmas were subsequently modified by frequent recharge of more mafic magmas with lower 87Sr/86Sr ratios. A typical Uturuncu silicic magma therefore only attains its final composition just prior to or during eruption. In the Lazufre region of active surface uplift (~25˚14'S; Volcán Lastarria and Cordon del Azufre) closed system differentiation processes are not the only factors influencing silicic magma compositions. 87Sr/86Sr (0.70651-0.70715) and 206Pb/204Pb ratios (18.83-18.88) are highly elevated and143Nd/144Nd ratios (0.512364 -0.512493) are low relative to similar composition rocks from the "southern Cordillera domain." These data, along with major and trace element trends, reflect a multitude of differentiation processes and magma sources including crystallization-differentiation of more mafic magmas, melting and assimilation of older crustal rocks, and magma mixing and mingling. On an arc-wide scale silicic lavas erupted from three well-characterized composite volcanoes between 21oS and 22oS (Aucanquilcha, Ollagüe, and Uturuncu) display systematically higher K2O, LILE, REE and HFSE contents and 87Sr/86Sr ratios with increasing distance from the arc-front. In contrast, the lavas have systematically lower Na2O, Sr, and Ba contents; LILE/HFSE ratios; 143Nd/144Nd ratios; and more negative Eu anomalies. Silicic magmas along the arc-front apparently reflect melting of relatively young, mafic composition amphibolitic source rocks with the continental crust becoming increasingly older with a more felsic bulk composition toward the east. We suggest this results from progressively smaller degrees of mantle partial melting, primary melt generation, and crustal hybridization with distance from the arc-front.

Self-reference and random sampling approach for label-free identification of DNA composition using plasmonic nanomaterials.

PubMed

Freeman, Lindsay M; Pang, Lin; Fainman, Yeshaiahu

2018-05-09

The analysis of DNA has led to revolutionary advancements in the fields of medical diagnostics, genomics, prenatal screening, and forensic science, with the global DNA testing market expected to reach revenues of USD 10.04 billion per year by 2020. However, the current methods for DNA analysis remain dependent on the necessity for fluorophores or conjugated proteins, leading to high costs associated with consumable materials and manual labor. Here, we demonstrate a potential label-free DNA composition detection method using surface-enhanced Raman spectroscopy (SERS) in which we identify the composition of cytosine and adenine within single strands of DNA. This approach depends on the fact that there is one phosphate backbone per nucleotide, which we use as a reference to compensate for systematic measurement variations. We utilize plasmonic nanomaterials with random Raman sampling to perform label-free detection of the nucleotide composition within DNA strands, generating a calibration curve from standard samples of DNA and demonstrating the capability of resolving the nucleotide composition. The work represents an innovative way for detection of the DNA composition within DNA strands without the necessity of attached labels, offering a highly sensitive and reproducible method that factors in random sampling to minimize error.

Lithium isotopic systematics of submarine vent fluids from arc and back-arc hydrothermal systems in the western Pacific

NASA Astrophysics Data System (ADS)

Araoka, Daisuke; Nishio, Yoshiro; Gamo, Toshitaka; Yamaoka, Kyoko; Kawahata, Hodaka

2016-10-01

The Li concentration and isotopic composition (δ7Li) in submarine vent fluids are important for oceanic Li budget and potentially useful for investigating hydrothermal systems deep under the seafloor because hydrothermal vent fluids are highly enriched in Li relative to seawater. Although Li isotopic geochemistry has been studied at mid-ocean-ridge (MOR) hydrothermal sites, in arc and back-arc settings Li isotopic composition has not been systematically investigated. Here we determined the δ7Li and 87Sr/86Sr values of 11 end-member fluids from 5 arc and back-arc hydrothermal systems in the western Pacific and examined Li behavior during high-temperature water-rock interactions in different geological settings. In sediment-starved hydrothermal systems (Manus Basin, Izu-Bonin Arc, Mariana Trough, and North Fiji Basin), the Li concentrations (0.23-1.30 mmol/kg) and δ7Li values (+4.3‰ to +7.2‰) of the end-member fluids are explained mainly by dissolution-precipitation model during high-temperature seawater-rock interactions at steady state. Low Li concentrations are attributable to temperature-related apportioning of Li in rock into the fluid phase and phase separation process. Small variation in Li among MOR sites is probably caused by low-temperature alteration process by diffusive hydrothermal fluids under the seafloor. In contrast, the highest Li concentrations (3.40-5.98 mmol/kg) and lowest δ7Li values (+1.6‰ to +2.4‰) of end-member fluids from the Okinawa Trough demonstrate that the Li is predominantly derived from marine sediments. The variation of Li in sediment-hosted sites can be explained by the differences in degree of hydrothermal fluid-sediment interactions associated with the thickness of the marine sediment overlying these hydrothermal sites.

Soft Chemical Fabrication of Iron-Based Thin Film Electrocatalyst for Water Oxidation under Neutral pH and Structure-Activity Tuning by Cerium Incorporation.

PubMed

Saha, Jony; Radhakrishnan, T P

2017-08-29

Design of electrocatalysts for the fundamentally important oxygen evolution reaction can be greatly aided by systematic structure-activity tuning via composition variation. We have explored the iron-cerium system as they are the most abundant transition and rare earth metals, and also due to the mutualistic impact of their size and electronic attributes that can induce critical changes in the structure and electrochemical activity. Submicrometer thick films of a series of Fe(III)-Ce(III) phosphate(oxyhydroxide) (FeCePH) are fabricated using a soft chemical strategy involving surfactant-aided assembly, spin-coating, and mild thermal annealing. FT-IR, Raman, and X-ray photoelectron spectroscopies, chemical analysis, X-ray diffraction, and electron microscopy reveal the systematic structural, electronic, and morphological variation, on tuning the iron-cerium composition. Nitrogen adsorption-desorption studies show the surface area increasing and pore size distribution shrinking with the cerium content, indicating its structure-directing role. The electrocatalysis of water oxidation by FeCePH films on FTO-coated glass is studied in neutral pH conditions. The overpotential and Tafel slope decrease with increasing cerium content, reaching minima at the optimal Fe:Ce ratio of 1:0.5; the turnover frequency shows a corresponding increase and maximum. The trends are explained on the basis of the structural changes in the films, and the coupling of Ce 3+ /Ce 4+ with Fe 3+ /Fe 4+ that leads to active state regeneration. This study presents a rational strategy to tune the efficiency of easily fabricated transition metal-based electrocatalyst thin films through rare earth metal incorporation; it should prove useful in the design of cost-effective catalysts for water oxidation.

Discordances originated by multiple meta-analyses on interventions for myocardial infarction: a systematic review.

PubMed

Lucenteforte, Ersilia; Moja, Lorenzo; Pecoraro, Valentina; Conti, Andrea A; Conti, Antonio; Crudeli, Elena; Galli, Alessio; Gensini, Gian Franco; Minnelli, Martina; Mugelli, Alessandro; Proietti, Riccardo; Shtylla, Jonida; D'Amico, Roberto; Parmelli, Elena; Virgili, Gianni

2015-03-01

To clarify the impact of multiple (covering the same population, intervention, control, and outcomes) systematic reviews (SRs) on interventions for myocardial infarction (MI). Clinical Evidence (BMJ Group) sections and related search strategies regarding MI were used to identify multiple SRs published between 1997 and 2007. Multiple SRs were classified as discordant if they featured conflicting results or interpretation of them. Thirty-six SRs (23.5% of 153 on the treatment or prevention of MI) were classified as multiple and grouped in 16 clusters [ie, at least two SRs with the same PICO (population, condition/disease, intervention, control) and at least one common outcome] exploring angioplasty, angiotensin-converting enzyme inhibitors, anticoagulants, antiplatelets, β-blockers, and stents. Complete agreement on statistically significant differences between interventions was found in 7 of 10 clusters with a shared composite outcome. Agreement was reduced when single outcomes were considered. Despite substantial variation and limited agreement in reporting of major outcomes, SRs agreed in their conclusions on the superiority of either the intervention or control in 14 of 16 clusters. Sources of minor discrepancies were found in terms of study and outcome selection, subgroup analyses, and interpretation of findings. Multiple SRs agreed in their qualitative conclusions but not on reporting and on analyses of hard outcomes. Discordance on significance of treatment effects was due to a combination of variation in design with inclusion of different studies and lack of precision for single hard outcomes compared with a composite outcome. Such inconsistencies among SRs could potentially slow the translation of SRs' results to clinical and public health decision making and suggest the need for a broader methodological and clinical agreement on their design. Copyright © 2015 Elsevier Inc. All rights reserved.

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

Guo, Hengxiao; Gu, Minfeng, E-mail: hxguo@shao.ac.cn, E-mail: gumf@shao.ac.cn

We investigated the optical/ultraviolet (UV) color variations for a sample of 2169 quasars based on multi-epoch spectroscopy in the Sloan Digital Sky Survey data releases seven (DR7) and nine (DR9). To correct the systematic difference between DR7 and DR9 due to the different instrumental setup, we produced a correction spectrum by using a sample of F-stars observed in both DR7 and DR9. The correction spectrum was then applied to quasars when comparing the spectra of DR7 with DR9. In each object, the color variation was explored by comparing the spectral index of the continuum power-law fit on the brightest spectrummore » with the faintest one, and also by the shape of their difference spectrum. In 1876 quasars with consistent color variations from two methods, we found that most sources (1755, ∼94%) show the bluer-when-brighter (BWB) trend, and the redder-when-brighter (RWB) trend is detected in only 121 objects (∼6%). The common BWB trend is supported by the composite spectrum constructed from bright spectra, which is bluer than that from faint spectra, and also by the blue composite difference spectrum. The correction spectrum is proven to be highly reliable by comparing the composite spectrum from corrected DR9 and original DR7 spectra. Assuming that the optical/UV variability is triggered by fluctuations, the RWB trend can likely be explained if the fluctuations occur first in the outer disk region, and the inner disk region has not yet fully responded when the fluctuations are being propagated inward. In contrast, the common BWB trend implies that the fluctuations likely more often happen first in the inner disk region.« less

Benchmarking health system performance across districts in Zambia: a systematic analysis of levels and trends in key maternal and child health interventions from 1990 to 2010.

PubMed

Colson, Katherine Ellicott; Dwyer-Lindgren, Laura; Achoki, Tom; Fullman, Nancy; Schneider, Matthew; Mulenga, Peter; Hangoma, Peter; Ng, Marie; Masiye, Felix; Gakidou, Emmanuela

2015-04-02

Achieving universal health coverage and reducing health inequalities are primary goals for an increasing number of health systems worldwide. Timely and accurate measurements of levels and trends in key health indicators at local levels are crucial to assess progress and identify drivers of success and areas that may be lagging behind. We generated estimates of 17 key maternal and child health indicators for Zambia's 72 districts from 1990 to 2010 using surveys, censuses, and administrative data. We used a three-step statistical model involving spatial-temporal smoothing and Gaussian process regression. We generated estimates at the national level for each indicator by calculating the population-weighted mean of the district values and calculated composite coverage as the average of 10 priority interventions. National estimates masked substantial variation across districts in the levels and trends of all indicators. Overall, composite coverage increased from 46% in 1990 to 73% in 2010, and most of this gain was attributable to the scale-up of malaria control interventions, pentavalent immunization, and exclusive breastfeeding. The scale-up of these interventions was relatively equitable across districts. In contrast, progress in routine services, including polio immunization, antenatal care, and skilled birth attendance, stagnated or declined and exhibited large disparities across districts. The absolute difference in composite coverage between the highest-performing and lowest-performing districts declined from 37 to 26 percentage points between 1990 and 2010, although considerable variation in composite coverage across districts persisted. Zambia has made marked progress in delivering maternal and child health interventions between 1990 and 2010; nevertheless, substantial variations across districts and interventions remained. Subnational benchmarking is important to identify these disparities, allowing policymakers to prioritize areas of greatest need. Analyses such as this one should be conducted regularly and feed directly into policy decisions in order to increase accountability at the local, regional, and national levels.

Information-theoretic measures of hydrogen-like ions in weakly coupled Debye plasmas

NASA Astrophysics Data System (ADS)

Zan, Li Rong; Jiao, Li Guang; Ma, Jia; Ho, Yew Kam

2017-12-01

Recent development of information theory provides researchers an alternative and useful tool to quantitatively investigate the variation of the electronic structure when atoms interact with the external environment. In this work, we make systematic studies on the information-theoretic measures for hydrogen-like ions immersed in weakly coupled plasmas modeled by Debye-Hückel potential. Shannon entropy, Fisher information, and Fisher-Shannon complexity in both position and momentum spaces are quantified in high accuracy for the hydrogen atom in a large number of stationary states. The plasma screening effect on embedded atoms can significantly affect the electronic density distributions, in both conjugate spaces, and it is quantified by the variation of information quantities. It is shown that the composite quantities (the Shannon entropy sum and the Fisher information product in combined spaces and Fisher-Shannon complexity in individual space) give a more comprehensive description of the atomic structure information than single ones. The nodes of wave functions play a significant role in the changes of composite information quantities caused by plasmas. With the continuously increasing screening strength, all composite quantities in circular states increase monotonously, while in higher-lying excited states where nodal structures exist, they first decrease to a minimum and then increase rapidly before the bound state approaches the continuum limit. The minimum represents the most reduction of uncertainty properties of the atom in plasmas. The lower bounds for the uncertainty product of the system based on composite information quantities are discussed. Our research presents a comprehensive survey in the investigation of information-theoretic measures for simple atoms embedded in Debye model plasmas.

Thermal Phase Variations of WASP-12b: Defying Predictions

NASA Technical Reports Server (NTRS)

Cowan, Nicolas B.; Machalek, Pavel; Croll, Bryce; Shekhtman, Louis M.; Burrows, Adam; Deming, Drake; Greene, Tom; Hora, Joseph L.

2012-01-01

We report Warm Spitzer full-orbit phase observations of WASP-12b at 3.6 and 4.5 micrometers. This extremely inflated hot Jupiter is thought to be overflowing its Roche lobe, undergoing mass loss and accretion onto its host star, and has been claimed to have a C/O ratio in excess of unity. We are able to measure the transit depths, eclipse depths, thermal and ellipsoidal phase variations at both wavelengths. The large-amplitude phase variations, combined with the planet's previously measured dayside spectral energy distribution, are indicative of non-zero Bond albedo and very poor day-night heat redistribution. The transit depths in the mid-infrared-(R(sub p)/R(sub *))(sup 2) = 0.0123(3) and 0.0111(3) at 3.6 and 4.5 micrometers, respectively-indicate that the atmospheric opacity is greater at 3.6 than at 4.5 micrometers, in disagreement with model predictions, irrespective of C/O ratio. The secondary eclipse depths are consistent with previous studies: F(sub day)/F(sub *) = 0.0038(4) and 0.0039(3) at 3.6 and 4.5 micrometers, respectively. We do not detect ellipsoidal variations at 3.6 micrometers, but our parameter uncertainties-estimated via prayer-bead Monte Carlo-keep this non-detection consistent with model predictions. At 4.5 micrometers, on the other hand, we detect ellipsoidal variations that are much stronger than predicted. If interpreted as a geometric effect due to the planet's elongated shape, these variations imply a 3:2 ratio for the planet's longest:shortest axes and a relatively bright day-night terminator. If we instead presume that the 4.5 micrometer ellipsoidal variations are due to uncorrected systematic noise and we fix the amplitude of the variations to zero, the best-fit 4.5 micrometer transit depth becomes commensurate with the 3.6 micrometer depth, within the uncertainties. The relative transit depths are then consistent with a solar composition and short scale height at the terminator. Assuming zero ellipsoidal variations also yields a much deeper 4.5 micrometer eclipse depth, consistent with a solar composition and modest temperature inversion. We suggest future observations that could distinguish between these two scenarios.

Thermal Phase Variations of WASP-12b: Defying Predictions

NASA Astrophysics Data System (ADS)

Cowan, Nicolas B.; Machalek, Pavel; Croll, Bryce; Shekhtman, Louis M.; Burrows, Adam; Deming, Drake; Greene, Tom; Hora, Joseph L.

2012-03-01

We report Warm Spitzer full-orbit phase observations of WASP-12b at 3.6 and 4.5 μm. This extremely inflated hot Jupiter is thought to be overflowing its Roche lobe, undergoing mass loss and accretion onto its host star, and has been claimed to have a C/O ratio in excess of unity. We are able to measure the transit depths, eclipse depths, thermal and ellipsoidal phase variations at both wavelengths. The large-amplitude phase variations, combined with the planet's previously measured dayside spectral energy distribution, are indicative of non-zero Bond albedo and very poor day-night heat redistribution. The transit depths in the mid-infrared—(Rp /R *)2 = 0.0123(3) and 0.0111(3) at 3.6 and 4.5 μm, respectively—indicate that the atmospheric opacity is greater at 3.6 than at 4.5 μm, in disagreement with model predictions, irrespective of C/O ratio. The secondary eclipse depths are consistent with previous studies: F day/F * = 0.0038(4) and 0.0039(3) at 3.6 and 4.5 μm, respectively. We do not detect ellipsoidal variations at 3.6 μm, but our parameter uncertainties—estimated via prayer-bead Monte Carlo—keep this non-detection consistent with model predictions. At 4.5 μm, on the other hand, we detect ellipsoidal variations that are much stronger than predicted. If interpreted as a geometric effect due to the planet's elongated shape, these variations imply a 3:2 ratio for the planet's longest:shortest axes and a relatively bright day-night terminator. If we instead presume that the 4.5 μm ellipsoidal variations are due to uncorrected systematic noise and we fix the amplitude of the variations to zero, the best-fit 4.5 μm transit depth becomes commensurate with the 3.6 μm depth, within the uncertainties. The relative transit depths are then consistent with a solar composition and short scale height at the terminator. Assuming zero ellipsoidal variations also yields a much deeper 4.5 μm eclipse depth, consistent with a solar composition and modest temperature inversion. We suggest future observations that could distinguish between these two scenarios.

A method for inferring the rate of evolution of homologous characters that can potentially improve phylogenetic inference, resolve deep divergence and correct systematic biases.

PubMed

Cummins, Carla A; McInerney, James O

2011-12-01

Current phylogenetic methods attempt to account for evolutionary rate variation across characters in a matrix. This is generally achieved by the use of sophisticated evolutionary models, combined with dense sampling of large numbers of characters. However, systematic biases and superimposed substitutions make this task very difficult. Model adequacy can sometimes be achieved at the cost of adding large numbers of free parameters, with each parameter being optimized according to some criterion, resulting in increased computation times and large variances in the model estimates. In this study, we develop a simple approach that estimates the relative evolutionary rate of each homologous character. The method that we describe uses the similarity between characters as a proxy for evolutionary rate. In this article, we work on the premise that if the character-state distribution of a homologous character is similar to many other characters, then this character is likely to be relatively slowly evolving. If the character-state distribution of a homologous character is not similar to many or any of the rest of the characters in a data set, then it is likely to be the result of rapid evolution. We show that in some test cases, at least, the premise can hold and the inferences are robust. Importantly, the method does not use a "starting tree" to make the inference and therefore is tree independent. We demonstrate that this approach can work as well as a maximum likelihood (ML) approach, though the ML method needs to have a known phylogeny, or at least a very good estimate of that phylogeny. We then demonstrate some uses for this method of analysis, including the improvement in phylogeny reconstruction for both deep-level and recent relationships and overcoming systematic biases such as base composition bias. Furthermore, we compare this approach to two well-established methods for reweighting or removing characters. These other methods are tree-based and we show that they can be systematically biased. We feel this method can be useful for phylogeny reconstruction, understanding evolutionary rate variation, and for understanding selection variation on different characters.

Synchrotron In-Situ Aging Study and Correlations to the γ' Phase Instabilities in a High-Refractory Content γ-γ' Ni-Base Superalloy

NASA Astrophysics Data System (ADS)

Antonov, Stoichko; Sun, Eugene; Tin, Sammy

2018-06-01

Detailed ex-situ electron microscopy and atom probe tomography (APT) were combined with in-situ synchrotron diffraction to systematically quantify the chemical, morphological, and lattice instabilities that occur during aging of a polycrystalline high-refractory content Ni-base superalloy. The morphological changes and splitting phenomenon associated with the secondary γ' precipitates were related to a combination of discrete chemical composition variations at the secondary γ'/γ interfaces and additional chemical energy arising from γ precipitates that form within the secondary γ' particles. The compositional phase inhomogeneities led to the precipitation of finely dispersed tertiary γ' particles within the γ matrix and secondary γ particles within the secondary γ' precipitates, which, along with surface grooving of the secondary γ' particles, likely due to a spike in the lattice misfit at the particle interfaces, contributed to the splitting of the precipitates during aging.

Characterisation of a garnet population from the Sikkim Himalaya: implications for the mechanisms and rates of porphyroblast crystallisation

NASA Astrophysics Data System (ADS)

George, Freya; Gaidies, Fred

2016-04-01

Analysis of porphyroblast distribution in metamorphic rocks yields insight into the processes controlling metamorphic reaction rates. By coupling this textural record with microprobe analysis and phase-equilibria and diffusion modelling, a detailed view of the nucleation and growth history of metamorphic minerals can be obtained. In this study, we comprehensively characterise the 3D distribution and compositional variation of a garnet population in a garnet-grade pelitic schist of the Lesser Himalayan Sequence (Sikkim), in order to investigate both the rates and kinetic controls of porphyroblastic crystallisation. Quantification of the size, shape and spatial distribution of garnet using high-resolution μ-computed X-ray tomography and statistical analysis reveals a log-normal crystal size distribution, systematic variation of aspect ratio with crystal size, and a significantly clustered garnet texture in the study sample. The latter is indicative of interface-controlled nucleation and growth, with nucleation sites controlled principally by a heterogeneous precursor assemblage. At length-scales less than 0.7 mm, there is evidence for adjacent grains that are on average smaller than the mean size of the population; this minor ordering is attributed to secondary redistribution of porphyroblast centers and reduction of crystal sizes due to syn-kinematic growth and resorption, respectively. Geochemical traverses through centrally sectioned garnet crystals of variable size highlight several features: (1) core compositions of even the smallest crystals preserve primary prograde growth zonation, with little evidence for diffusional modification in any crystal size; (2) rim compositions are within error between grains, suggestive of sample-scale equilibration of the growth medium at the time of cessation of crystallisation; (3) different grains of equal radii display equivalent compositional zoning; and (4) gradients of compositional profiles display a steepening trend in progressively smaller grain sizes, converse to anticipated trends based on classic kinetic crystallisation theory. The observed systematic behaviour is interpreted to reflect interface-controlled rates of crystallisation, with a decrease in the rate of crystal growth of newly nucleated grains as the crystallisation interval proceeds. Numerical simulations of garnet growth successfully reproduce observed core and rim compositions, and simulations of intracrystalline diffusion yield rapid heating/cooling rates along the P-T path, in excess of 100 °C/Ma. Radial garnet crystallisation is correspondingly rapid, with minimum growth rates of 1.5 mm/Ma in the smallest crystals. Simulations suggest progressive nucleation of new generations of garnet occurred with an exponentially decreasing frequency along the prograde path; however, measured gradients indicate that core compositions developed more slowly than predicted by the model, potentially resulting in a more evenly distributed pattern of nucleation.

Elemental composition of solar energetic particles

NASA Technical Reports Server (NTRS)

Cook, W. R.; Stone, E. C.; Vogt, R. E.

1984-01-01

The Low Energy Telescopes on the Voyager spacecraft have been used to measure the elemental composition (Z = 2-28) and energy spectra (5-15 MeV per nucleon) of solar energetic particles (SEPs) in seven large flare events. Four flare events were selected which have SEP abundance ratios approximately independent of energy per nucleon. For these selected flare events, SEP composition results may be described by an average composition plus a systematic flare-to-flare deviation about the average. The four-flare average SEP composition is systematically different from the solar composition determined by photospheric spectroscopy. These systematic composition differences are apparently not due to SEP propagation or acceleration effects. In contrast, the four-flare average SEP composition is in agreement with measured solar wind abundances and with a number of recent spectroscopic coronal abundance measurements. These findings suggest that SEPs originate in the corona, and that both SEPs and the solar wind sample a coronal composition which is significantly and persistently different from that measured for the photosphere.

Dynamic behavior of geometrically complex hybrid composite samples in a Split-Hopkinson Pressure Bar system

NASA Astrophysics Data System (ADS)

Pouya, M.; Balasubramaniam, S.; Sharafiev, S.; F-X Wagner, M.

2018-06-01

The interfaces between layered materials play an important role for the overall mechanical behavior of hybrid composites, particularly during dynamic loading. Moreover, in complex-shaped composites, interfacial failure is strongly affected by the geometry and size of these contact interfaces. As preliminary work for the design of a novel sample geometry that allows to analyze wave reflection phenomena at the interfaces of such materials, a series of experiments using a Split-Hopkinson Pressure Bar technique was performed on five different sample geometries made of a monomaterial steel. A complementary explicit finite element model of the Split-Hopkinson Pressure Bar system was developed and the same sample geometries were studied numerically. The simulated input, reflected and transmitted elastic wave pulses were analyzed for the different sample geometries and were found to agree well with the experimental results. Additional simulations using different composite layers of steel and aluminum (with the same sample geometries) were performed to investigate the effect of material variation on the propagated wave pulses. The numerical results show that the reflected and transmitted wave pulses systematically depend on the sample geometry, and that elastic wave pulse propagation is affected by the properties of individual material layers.

The Impact of Chemical Substitutions on Interfacial Properties of REE Orthophosphates (Monazite, Xenotime)

NASA Astrophysics Data System (ADS)

Gamage McEvoy, J.; Thibault, Y.

2016-12-01

Mineral surface properties strongly influence liquid-solid interface behaviour in the presence of various ligands, and can significantly affect processes of natural (ex. fluids, melts) and industrial (ex. oil recovery) relevance. Many Rare Earth Element (REE)-bearing minerals display extensive solid solutions resulting in significant chemical variations which influence their crystal and surface properties and, can consequently impact the interfacial features of their interaction with substances such as organic molecules (i.e. reactivity and sorption). For example, the surface charge properties of some REE orthophosphates show an uncharacteristically wide variation in reported values, where large differences in literature are commonly attributed to compositional differences between samples. However the impact of these chemical substitutions remains largely unknown. As such, the aim of this research was to systematically investigate the influence of mineralogical variation within the compositional space of the REE orthophosphates on their surface chemistry and resulting interaction with organic molecules. To better isolate the chemical, structural, and morphological variables, the synthesis of REE orthophosphate crystals along a number of defined substitutions was conducted, and their surface chemistry characteristics benchmarked against well-characterized natural monazite and xenotime from various localities. The interaction of these crystal surfaces with model organic molecules (long chain carboxylic acids and alkyl hydroxamic acids, respectively) was then studied and characterized via surface (X-ray photoelectron) and near-surface (vibrational) spectroscopic techniques. The implications of crystal surface-organic molecule interactions to mineral processing through flotation were also experimentally investigated.

The Surtsey Magma Series

PubMed Central

Ian Schipper, C.; Jakobsson, Sveinn P.; White, James D.L.; Michael Palin, J.; Bush-Marcinowski, Tim

2015-01-01

The volcanic island of Surtsey (Vestmannaeyjar, Iceland) is the product of a 3.5-year-long eruption that began in November 1963. Observations of magma-water interaction during pyroclastic episodes made Surtsey the type example of shallow-to-emergent phreatomagmatic eruptions. Here, in part to mark the 50th anniversary of this canonical eruption, we present previously unpublished major-element whole-rock compositions, and new major and trace-element compositions of sideromelane glasses in tephra collected by observers and retrieved from the 1979 drill core. Compositions became progressively more primitive as the eruption progressed, with abrupt changes corresponding to shifts between the eruption’s four edifices. Trace-element ratios indicate that the chemical variation is best explained by mixing of different proportions of depleted ridge-like basalt, with ponded, enriched alkalic basalt similar to that of Iceland’s Eastern Volcanic Zone; however, the systematic offset of Surtsey compositions to lower Nb/Zr than other Vestmannaeyjar lavas indicates that these mixing end members are as-yet poorly contained by compositions in the literature. As the southwestern-most volcano in the Vestmannaeyjar, the geochemistry of the Surtsey Magma Series exemplifies processes occurring within ephemeral magma bodies on the extreme leading edge of a propagating off-axis rift in the vicinity of the Iceland plume. PMID:26112644

Optical properties of base dentin ceramics for all-ceramic restorations.

PubMed

Shiraishi, Takanobu; Wood, Duncan J; Shinozaki, Nobuya; van Noort, Richard

2011-02-01

The study was conducted to compare the optical parameters of VM7(®) M-shade base dentin ceramics (VITA, Germany) for all ceramic restorations to the chemical composition across the 3D-MASTER(®) shade system. Three disc samples, 13 mm diameter and 1.4 mm thickness, were produced for each M-shade following the manufacturer's instructions. Each disc was ground and polished to a thickness of 1.0 mm. Spectral light transmittance and reflectance data were recorded in the visible spectrum under the standard illuminant D65 and 2° observer at 10 nm intervals by using a computer-controlled spectrophotometer. Opacity, translucency and opalescence parameters were determined for each sample. (1) Spectral transmittance and reflectance in the short-wavelength range systematically decreased with increasing chroma number (M1, M2, M3) when compared within the same value (lightness) group. (2) Spectral transmittance and reflectance decreased systematically across the whole visible spectrum with increasing value group number when compared within the same chroma group. (3) Analysis of relationship between chemical composition and various optical parameters for all the samples showed the significant contribution of ZrO₂ and Y₂O₃ substances to optical properties of the present material. Systematic variations in optical properties of VM7(®) M-shade base dentin ceramics were observed throughout the 3D-MASTER(®) shade system and were suggested to be caused by the fine structure of the sample which can interfere with shorter wavelengths in the visible spectrum. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Kinetic Control of Aqueous Hydrolysis: Modulating Structure/Property Relationships in Inorganic Crystals

NASA Astrophysics Data System (ADS)

Neilson, James R.

2011-12-01

A grand challenge in materials science and chemistry revolves around the preparation of materials with desired properties by controlling structure on multiple length scales. Biology approaches this challenge by evolving tactics to transform soluble precursors into materials and composites with macro-scale and atomic precision. Studies of biomineralization in siliceous sponges led to the discovery of slow, catalytic hydrolysis of molecular precursors in the biogenesis of silica skeletal elements with well defined micro- and nano-scale architectures. However, the role of aqueous hydrolysis in the limit of kinetic control is not well understood; this allows us to form a central hypothesis: that the kinetics of hydrolysis modulate the structures of materials and their properties. As a model system, the diffusion of a simple hydrolytic catalyst (such as ammonia) across an air-water interface into a metal salt solution reproduces some aspects of the chemistry found in biomineralization, namely kinetic and vectorial control. Variation of the catalyst concentration modulates the hydrolysis rate, and thus alters the resulting structure of the inorganic crystals. Using aqueous solutions of cobalt(II) chloride, each product (cobalt hydroxide chloride) forms with a unique composition, despite being prepared from identical mother liquors. Synchrotron X-ray total scattering methods are needed to locate the atomic positions in the material, which are not aptly described by a traditional crystallographic unit cell due to structural disorder. Detailed definition of the structure confirms that the hydrolysis conditions systematically modulate the arrangement of atoms in the lattice. This tightly coupled control of crystal formation and knowledge of local and average structures of these materials provides insight into the unusual magnetic properties of these cobalt hydroxides. The compounds studied show significant and open magnetization loops with little variation with composition or structure, yet subtle and systematic changes in the mean-field spin interaction strength and spin entropy loss. Meanwhile, neutron powder diffraction reveals a fully compensated Ńeel state; a detailed analysis of the local structure defines the aperiodic clusters of polyhedra responsible for magnetic order. The rate of hydrolysis of metal precursors modulates the disposition of these polyhedral clusters. The strategy of kinetically controlling aqueous hydrolysis also extends to the formation of stoichiometrically ordered bimetallic crystals [MSn(OH)6], where the hydrolysis behavior for dissimilar metal cations must be controlled via counteranions or precursor selection. In the formation of these ordered double perovskite hydroxides, the rate of hydrolysis is held constant in the limit of kinetic control. Instead, the propensities of different cations to undergo controlled hydrolysis are probed by their ability to form ordered crystals. Collectively, these studies demonstrate how systematic variation in the kinetic conditions of materials preparation and the character of each solute control the structure and properties of materials, with a precision not attainable through traditional or near-equilibrium approaches.

Silicon isotope fractionation in bamboo and its significance to the biogeochemical cycle of silicon

NASA Astrophysics Data System (ADS)

Ding, T. P.; Zhou, J. X.; Wan, D. F.; Chen, Z. Y.; Wang, C. Y.; Zhang, F.

2008-03-01

A systematic investigation on silica contents and silicon isotope compositions of bamboos was undertaken. Seven bamboo plants and related soils were collected from seven locations in China. The roots, stem, branch and leaves for each plant were sampled and their silica contents and silicon isotope compositions were determined. The silica contents and silicon isotope compositions of bulk and water-soluble fraction of soils were also measured. The silica contents of studied bamboo organs vary from 0.30% to 9.95%. Within bamboo plant the silica contents show an increasing trend from stem, through branch, to leaves. In bamboo roots the silica is exclusively in the endodermis cells, but in stem, branch and leaves, the silica is accumulated mainly in epidermal cells. The silicon isotope compositions of bamboos exhibit significant variation, from -2.3‰ to 1.8‰, and large and systematic silicon isotope fractionation was observed within each bamboo. The δ 30Si values decrease from roots to stem, but then increase from stem, through branch, to leaves. The ranges of δ 30Si values within each bamboo vary from 1.0‰ to 3.3‰. Considering the total range of silicon isotope composition in terrestrial samples is only 7‰, the observed silicon isotope variation in single bamboo is significant and remarkable. This kind of silicon isotope variation might be caused by isotope fractionation in a Rayleigh process when SiO 2 precipitated in stem, branches and leaves gradually from plant fluid. In this process the Si isotope fractionation factor between dissolved Si and precipitated Si in bamboo ( αpre-sol) is estimated to be 0.9981. However, other factors should be considered to explain the decrease of δ 30Si value from roots to stem, including larger ratio of dissolved H 4SiO 4 to precipitated SiO 2 in roots than in stem. There is a positive correlation between the δ 30Si values of water-soluble fractions in soils and those of bulk bamboos, indicating that the dissolved silicon in pore water and phytoliths in soil is the direct sources of silicon taken up by bamboo roots. A biochemical silicon isotope fractionation exists in process of silicon uptake by bamboo roots. Its silicon isotope fractionation factor ( αbam-wa) is estimated to be 0.9988. Considering the distribution patterns of SiO 2 contents and δ 30Si values among different bamboo organs, evapotranspiration may be the driving force for an upward flow of a silicon-bearing fluid and silica precipitation. Passive silicon uptake and transportation may be important for bamboo, although the role of active uptake of silicic acid by roots may not be neglected. The samples with relatively high δ 30Si values all grew in soils showing high content of organic materials. In contrast, the samples with relatively low δ 30Si values all grew in soil showing low content of organic materials. The silicon isotope composition of bamboo may reflect the local soil type and growth conditions. Our study suggests that bamboos may play an important role in global silicon cycle.

Tennantite-tetrahedrite series from the Madan Pb-Zn deposits, Central Rhodopes, Bulgaria

NASA Astrophysics Data System (ADS)

Vassileva, Rossitsa D.; Atanassova, Radostina; Kouzmanov, Kalin

2014-08-01

Minerals from the tennantite-tetrahedrite series (fahlores) are found as single euhedral crystals and crustiform aggregates in hydrothermal veins of the Gradishte and Petrovitsa Pb-Zn deposits of the Madan ore field, southern Bulgaria. Unusually large compositional variations and fine oscillatory crystal zoning were investigated with electron microprobe analysis. The Gradishte samples correspond dominantly to tennantite, while Petrovitsa crystals have exclusively tetrahedrite composition. Fahlore compositions at Madan correspond to zincian varieties (1.6-1.95 apfu), with low Fe-content (<0.45 apfu). Minor silver is characteristic only for the Petrovitsa samples, reaching a maximum of 0.30 apfu. The (Cu+Ag) content of the Petrovitsa tennantites and the Cu content of the Gradishte tetrahedrites systematically exceed 10 apfu resulting in compensation of the excess Cu in the structure by Fe3+. Textural characteristics, mineral relationships and available fluid inclusion and stable isotope data suggest that fahlores precipitated in the late stages of mineralization at Madan, at temperature interval of 300-200 °C from oxidizing fluids with mixed (magmatic-meteoric) signatures.

PMN-PT based quaternary piezoceramics with enhanced piezoelectricity and temperature stability

NASA Astrophysics Data System (ADS)

Luo, Nengneng; Zhang, Shujun; Li, Qiang; Yan, Qingfeng; He, Wenhui; Zhang, Yiling; Shrout, Thomas R.

2014-05-01

The phase structure, piezoelectric, dielectric, and ferroelectric properties of (0.80 - x)PMN-0.10PFN-0.10PZ-xPT were investigated systematically. The morphotropic phase boundary (MPB) was confirmed to be 0.30 < x < 0.34. Both MPB compositions of x = 0.32 and x = 0.33 exhibit high piezoelectric coefficients d33 = 640 pC/N and 580 pC/N, electromechanical couplings kp of 0.53 and 0.52, respectively. Of particular importance is that the composition with x = 0.33 was found to process high field-induced piezoelectric strain coefficient d33* of 680 pm/V, exhibiting a minimal temperature-dependent behavior, being less than 8% in the temperature range of 25-165 °C, which can be further confirmed by d31, with a variation of less than 9%. The temperature-insensitive d33* values can be explained by the counterbalance of the ascending dielectric permittivity and descending polarization with increasing temperature. These features make the PMN-PT based quaternary MPB compositions promising for actuator applications demanding high temperature stability.

Cenozoic marine geochemistry of thallium deduced from isotopic studies of ferromanganese crusts and pelagic sediments

USGS Publications Warehouse

Rehkamper, M.; Frank, M.; Hein, J.R.; Halliday, A.

2004-01-01

Cenozoic records of Tl isotope compositions recorded by ferromanganese (Fe-Mn) crusts have been obtained. Such records are of interest because recent growth surfaces of Fe-Mn crusts display a nearly constant Tl isotope fractionation relative to seawater. The time-series data are complemented by results for bulk samples and leachates of various marine sediments. Oxic pelagic sediments and anoxic marine deposits can be distinguished by their Tl isotope compositions. Both pelagic clays and biogenic oozes are typically characterized by ??205Tl greater than +2.5, whereas anoxic sediments have ??205Tl of less than -1.5 (??205Tl is the deviation of the 205Tl/203Tl isotope ratio of a sample from NIST SRM 997 Tl in parts per 104). Leaching experiments indicate that the high ??205Tl values of oxic sediments probably reflect authigenic Fe-Mn oxyhydroxides. Time-resolved Tl isotope compositions were obtained from six Fe-Mn crusts from the Atlantic, Indian, and Pacific oceans and a number of observations indicate that these records were not biased by diagenetic alteration. Over the last 25 Myr, the data do not show isotopic variations that significantly exceed the range of Tl isotope compositions observed for surface layers of Fe-Mn crusts distributed globally (??205 Tl=+12.8??1.2). This indicates that variations in deep-ocean temperature were not recorded by Tl isotopes. The results most likely reflect a constant Tl isotope composition for seawater. The growth layers of three Fe-Mn crusts that are older than 25 Ma show a systematic increase of ??205Tl with decreasing age, from about +6 at 60-50 Ma to about +12 at 25 Ma. These trends are thought to be due to variations in the Tl isotope composition of seawater, which requires that the oceans of the early Cenozoic either had smaller output fluxes or received larger input fluxes of Tl with low ??205Tl. Larger inputs of isotopically light Tl may have been supplied by benthic fluxes from reducing sediments, rivers, and/or volcanic emanations. Alternatively, the Tl isotope trends may reflect the increasing importance of Tl fluxes to altered ocean crust through time. ?? 2004 Elsevier B.V. All rights reserved.

Reuse at the Software Productivity Consortium

NASA Technical Reports Server (NTRS)

Weiss, David M.

1989-01-01

The Software Productivity Consortium is sponsored by 14 aerospace companies as a developer of software engineering methods and tools. Software reuse and prototyping are currently the major emphasis areas. The Methodology and Measurement Project in the Software Technology Exploration Division has developed some concepts for reuse which they intend to develop into a synthesis process. They have identified two approaches to software reuse: opportunistic and systematic. The assumptions underlying the systematic approach, phrased as hypotheses, are the following: the redevelopment hypothesis, i.e., software developers solve the same problems repeatedly; the oracle hypothesis, i.e., developers are able to predict variations from one redevelopment to others; and the organizational hypothesis, i.e., software must be organized according to behavior and structure to take advantage of the predictions that the developers make. The conceptual basis for reuse includes: program families, information hiding, abstract interfaces, uses and information hiding hierarchies, and process structure. The primary reusable software characteristics are black-box descriptions, structural descriptions, and composition and decomposition based on program families. Automated support can be provided for systematic reuse, and the Consortium is developing a prototype reuse library and guidebook. The software synthesis process that the Consortium is aiming toward includes modeling, refinement, prototyping, reuse, assessment, and new construction.

Evaluating Re-Os systematics in organic-rich sedimentary rocks in response to petroleum generation using hydrous pyrolysis experiments

USGS Publications Warehouse

Rooney, A.D.; Selby, D.; Lewan, M.D.; Lillis, P.G.; Houzay, J.-P.

2012-01-01

Successful application of the 187Re–187Os geochronometer has enabled the determination of accurate and precise depositional ages for organic-rich sedimentary rocks (ORS) as well as establishing timing constraints of petroleum generation. However, we do not fully understand the systematics and transfer behaviour of Re and Os between ORS and petroleum products (e.g., bitumen and oil). To more fully understand the behaviour of Re–Os systematics in both source rocks and petroleum products we apply hydrous pyrolysis to two immature hydrocarbon source rocks: the Permian Phosphoria Formation (TOC = 17.4%; Type II-S kerogen) and the Jurassic Staffin Formation (TOC = 2.5%; Type III kerogen). The laboratory-based hydrous pyrolysis experiments were carried out for 72 h at 250, 300, 325 and 350 °C. These experiments provided us with whole rock, extracted rock and bitumen and in some cases expelled oil and asphaltene for evaluation of Re–Os isotopic and elemental abundance. The data from these experiments demonstrate that the majority (>95%) of Re and Os are housed within extracted rock and that thermal maturation does not result in significant transfer of Re or Os from the extracted rock into organic phases. Based on existing thermodynamic data our findings suggest that organic chelating sites have a greater affinity for the quadravalent states of Re and Os than sulphides. Across the temperature range of the hydrous pyrolysis experiments both whole rock and extracted rock 187Re/188Os ratios show small variations (3.3% and 4.7%, for Staffin, respectively and 6.3% and 4.9% for Phosphoria, respectively). Similarly, the 187Os/188Os ratios show only minor variations for the Staffin and Phosphoria whole rock and extracted rock samples (0.6% and 1.4% and 1.3% and 2.2%). These isotopic data strongly suggest that crude oil generation through hydrous pyrolysis experiments does not disturb the Re–Os systematics in ORS as supported by various studies on natural systems. The elemental abundance data reveal limited transfer of Re and Os into the bitumen from a Type III kerogen in comparison to Type II-S kerogen (0.02% vs. 3.7%), suggesting that these metals are very tightly bound in Type III kerogen structure. The 187Os/188Os data from the pyrolysis generated Phosphoria bitumens display minor variation (4%) across the experimental temperatures, with values similar to that of the source rock. This indicates that the isotopic composition of the bitumen reflects the isotopic composition of the source rock at the time of petroleum generation. These data further support the premise that the Os isotopic composition of oils and bitumens can be used to fingerprint petroleum deposits to specific source rocks. Oil generated through the hydrous pyrolysis experiments does not contain appreciable quantities of Re or Os (~120 and ~3 ppt, respectively), in contrast to natural oils (2–50 ppb and 34–288 ppt for Re and Os, respectively), which may suggest that kinetic parameters are fundamental to the transfer of Re and Os from source rocks to oils. From this we hypothesise that, at the temperatures employed in hydrous pyrolysis, Re and Os are assimilated into the extracted rock as a result of cross-linking reactions.

Evaluating Re-Os systematics in organic-rich sedimentary rocks in response to petroleum generation using hydrous pyrolysis experiments

NASA Astrophysics Data System (ADS)

Rooney, Alan D.; Selby, David; Lewan, Michael D.; Lillis, Paul G.; Houzay, Jean-Pierre

2012-01-01

Successful application of the 187Re-187Os geochronometer has enabled the determination of accurate and precise depositional ages for organic-rich sedimentary rocks (ORS) as well as establishing timing constraints of petroleum generation. However, we do not fully understand the systematics and transfer behaviour of Re and Os between ORS and petroleum products (e.g., bitumen and oil). To more fully understand the behaviour of Re-Os systematics in both source rocks and petroleum products we apply hydrous pyrolysis to two immature hydrocarbon source rocks: the Permian Phosphoria Formation (TOC = 17.4%; Type II-S kerogen) and the Jurassic Staffin Formation (TOC = 2.5%; Type III kerogen). The laboratory-based hydrous pyrolysis experiments were carried out for 72 h at 250, 300, 325 and 350 °C. These experiments provided us with whole rock, extracted rock and bitumen and in some cases expelled oil and asphaltene for evaluation of Re-Os isotopic and elemental abundance. The data from these experiments demonstrate that the majority (>95%) of Re and Os are housed within extracted rock and that thermal maturation does not result in significant transfer of Re or Os from the extracted rock into organic phases. Based on existing thermodynamic data our findings suggest that organic chelating sites have a greater affinity for the quadravalent states of Re and Os than sulphides. Across the temperature range of the hydrous pyrolysis experiments both whole rock and extracted rock 187Re/188Os ratios show small variations (3.3% and 4.7%, for Staffin, respectively and 6.3% and 4.9% for Phosphoria, respectively). Similarly, the 187Os/188Os ratios show only minor variations for the Staffin and Phosphoria whole rock and extracted rock samples (0.6% and 1.4% and 1.3% and 2.2%). These isotopic data strongly suggest that crude oil generation through hydrous pyrolysis experiments does not disturb the Re-Os systematics in ORS as supported by various studies on natural systems. The elemental abundance data reveal limited transfer of Re and Os into the bitumen from a Type III kerogen in comparison to Type II-S kerogen (0.02% vs. 3.7%), suggesting that these metals are very tightly bound in Type III kerogen structure. The 187Os/188Os data from the pyrolysis generated Phosphoria bitumens display minor variation (4%) across the experimental temperatures, with values similar to that of the source rock. This indicates that the isotopic composition of the bitumen reflects the isotopic composition of the source rock at the time of petroleum generation. These data further support the premise that the Os isotopic composition of oils and bitumens can be used to fingerprint petroleum deposits to specific source rocks. Oil generated through the hydrous pyrolysis experiments does not contain appreciable quantities of Re or Os (∼120 and ∼3 ppt, respectively), in contrast to natural oils (2-50 ppb and 34-288 ppt for Re and Os, respectively), which may suggest that kinetic parameters are fundamental to the transfer of Re and Os from source rocks to oils. From this we hypothesise that, at the temperatures employed in hydrous pyrolysis, Re and Os are assimilated into the extracted rock as a result of cross-linking reactions.

Microphysical Cloud Regimes used as a tool to study Aerosol-Cloud-Precipitation-Radiation interactions

NASA Astrophysics Data System (ADS)

Cho, N.; Oreopoulos, L.; Lee, D.

2017-12-01

The presentation will examine whether the diagnostic relationships between aerosol and cloud-affected quantities (precipitation, radiation) obtained from sparse temporal resolution measurements from polar orbiting satellites can potentially demonstrate actual aerosol effects on clouds with appropriate analysis. The analysis relies exclusively on Level-3 (gridded) data and comprises systematic cloud classification in terms of "microphysical cloud regimes" (µCRs), aerosol optical depth (AOD) variations relative to a region's local seasonal climatology, and exploitation of the 3-hour difference between Terra (morning) and Aqua (afternoon) overpasses. Specifically, our presentation will assess whether Aerosol-Cloud-Precipitation-Radiation interactions (ACPRI) can be diagnosed by investigating: (a) The variations with AOD of afternoon cloud-affected quantities composited by afternoon or morning µCRs; (b) µCR transition diagrams composited by morning AOD quartiles; (c) whether clouds represented by ensemble cloud effective radius - cloud optical thickness joint histograms look distinct under low and high AOD conditions when preceded or followed by specific µCRs. We will explain how our approach addresses long-standing themes of the ACPRI problem such as the optimal ways to decompose the problem by cloud class, the prevalence and detectability of 1st/2nd aerosol indirect effects and invigoration, and the effectiveness of aerosol changes in inducing cloud modification at different segments of the AOD distribution.

Atmospheric controls on the precipitation isotopes over the Andaman Islands, Bay of Bengal

PubMed Central

Chakraborty, S.; Sinha, N.; Chattopadhyay, R.; Sengupta, S.; Mohan, P. M.; Datye, A.

2016-01-01

Isotopic analysis of precipitation over the Andaman Island, Bay of Bengal was carried out for the year 2012 and 2013 in order to study the atmospheric controls on rainwater isotopic variations. The oxygen and hydrogen isotopic compositions are typical of the tropical marine sites but show significant variations depending on the ocean-atmosphere conditions; maximum depletion was observed during the tropical cyclones. The isotopic composition of rainwater seems to be controlled by the dynamical nature of the moisture rather than the individual rain events. Precipitation isotopes undergo systematic depletions in response to the organized convection occurring over a large area and are modulated by the integrated effect of convective activities. Precipitation isotopes appear to be linked with the monsoon intraseasonal variability in addition to synoptic scale fluctuations. During the early to mid monsoon the amount effect arose primarily due to rain re-evaporation but in the later phase it was driven by moisture convergence rather than evaporation. Amount effect had distinct characteristics in these two years, which appeared to be modulated by the intraseasonal variability of monsoon. It is shown that the variable nature of amount effect limits our ability to reconstruct the past-monsoon rainfall variability on annual to sub-annual time scale. PMID:26806683

Systematic Relationships Between Lidar Observables and Sizes And Mineral Composition Of Dust Aerosols

NASA Technical Reports Server (NTRS)

Van Diedenhoven, Bastiaan; Stangl, Alexander; Perlwitz, Jan; Fridlind, Ann M.; Chowdhary, Jacek; Cairns, Brian

2015-01-01

The physical and chemical properties of soil dust aerosol particles fundamentally affect their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates on the surface of dust particles, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Lidar measurements, such as extinction-to-backscatter, color and depolarization ratios, are frequently used to distinguish between aerosol types with different physical and chemical properties. The chemical composition of aerosol particles determines their complex refractive index, hence affecting their backscattering properties. Here we present a study on how dust aerosol backscattering and depolarization properties at wavelengths of 355, 532 and 1064 nm are related to size and complex refractive index, which varies with the mineral composition of the dust. Dust aerosols are represented by collections of spheroids with a range of prolate and oblate aspect ratios and their optical properties are obtained using T-matrix calculations. We find simple, systematic relationships between lidar observables and the dust size and complex refractive index that may aid the use of space-based or airborne lidars for direct retrieval of dust properties or for the evaluation of chemical transport models using forward simulated lidar variables. In addition, we present first results on the spatial variation of forward-simulated lidar variables based on a dust model that accounts for the atmospheric cycle of eight different mineral types plus internal mixtures of seven mineral types with iron oxides, which was recently implemented in the NASA GISS Earth System ModelE2.

Origin of temporal compositional trends in monogenetic vent eruptions: Insights from the crystal cargo in the Papoose Canyon sequence, Big Pine Volcanic Field, CA

NASA Astrophysics Data System (ADS)

Gao, Ruohan; Lassiter, John C.; Ramirez, Gabrielle

2017-01-01

Many monogenetic vents display systematic temporal-compositional variations over the course of eruption. Previous studies have proposed that these trends may reflect variable degrees of crustal assimilation, or melting and mixing of heterogeneous mantle source(s). Discrimination between these two endmember hypotheses is critical for understanding the plumbing systems of monogenetic volcanoes, which pose a significant volcanic hazard in many areas. In this study, we examine the Papoose Canyon (PC) monogenetic vent in the Big Pine Volcanic Field (BPVF), which had been well characterized for temporal-compositional variations in erupted basalts. We present new major and trace element and Sr-Nd-Pb-O isotopic data from the PC "crystal cargo" (phenocrysts and xenoliths). Comparison of "crystal cargo" and host basalt provides new constraints on the history of magma storage, fractionation, and crustal contamination that are obscured in the bulk basalts due to pre- and syn-eruptive magma mixing processes. The abundances of phenocrysts and ultramafic xenoliths in the PC sequence decrease up-section. Olivine and clinopyroxene phenocrysts span a wide range of Mg# (77-89). The majority of phenocrysts are more evolved than olivine or clinopyroxene in equilibrium with their host basalts (Mg# = 68- 71, equilibrium Fo ≈ 85- 89). In addition, the ultramafic xenoliths display cumulate textures. Olivine and clinopyroxene from ultramafic xenoliths have Mg# (73-87) similar to the phenocrysts, and lower than typical mantle peridotites. Sr-Nd-Pb isotope compositions of the xenoliths are similar to early PC basalts. Finally, many clinopyroxene phenocrysts and clinopyroxene in xenoliths have trace element abundances in equilibrium with melts that are more enriched than the erupted basalts. These features suggest that the phenocrysts and xenoliths derive from melt that is more fractionated and enriched than erupted PC basalts. Pressure constraints suggest phenocrysts and ultramafic xenoliths crystallized at ∼5-7 kbar, corresponding to mid-crust depths. Correlations between HFSE depletion and Sr-Nd-Pb isotopic compositions, high δ18 O values in olivines, and radiogenic Os isotopic compositions in whole rocks also suggest incorporation of a crustally contaminated component. We propose that the phenocrysts and ultramafic xenoliths derive from melts that ponded and fractionated and assimilated continental crust, possibly in mid-crustal sills. These melts were drained and mixed with more primitive melts as the eruption began, and the temporal-compositional trends and decreasing crystal phase abundances reflect gradual deflation and exhaustion of these sills as the eruption progressed. The isotopic variations in the PC sequence span much of the compositional range observed in the BPVF. Evidence for variable crustal contamination of PC basalts suggests that much of the isotopic variation observed in the BPVF may also reflect crustal contamination rather than mantle source heterogeneity as previously proposed. In addition, evidence of pre-eruptive magma ponding and fractionation, if applicable to other monogenetic vents, may have significant implications for monitoring and hazard assessment of monogenetic volcano fields.

Functional gradients in the pericarp of the green coconut inspire asymmetric fibre-composites with improved impact strength, and preserved flexural and tensile properties.

PubMed

Graupner, Nina; Labonte, David; Humburg, Heide; Buzkan, Tayfun; Dörgens, Anna; Kelterer, Wiebke; Müssig, Jörg

2017-02-28

Here we investigate the mechanical properties and structural design of the pericarp of the green coconut (Cocos nucifera L.). The pericarp showed excellent impact characteristics, and mechanical tests of its individual components revealed gradients in stiffness, strength and elongation at break from the outer to the inner layer of the pericarp. In order to understand more about the potential effect of such gradients on 'bulk' material properties, we designed simple, graded, cellulose fibre-reinforced polylactide (PLA) composites by stacking layers reinforced with fibres of different mechanical properties. Tensile properties of the graded composites were largely determined by the 'weakest' fibre, irrespective of the fibre distribution. However, a graded design led to pronounced asymmetric bending and impact properties. Bio-inspired, asymmetrically graded composites showed a flexural strength and modulus comparable to that of the strongest reference samples, but the elongation at maximum load was dependent on the specimen orientation. The impact strength of the graded composites showed a similar orientation-dependence, and peak values exceeded the impact strength of a non-graded reference composite containing identical fibre fractions by up to a factor of three. In combination, our results show that an asymmetric, systematic variation of fibre properties can successfully combine desirable properties of different fibre types, suggesting new routes for the development of high-performance composites, and improving our understanding of the structure-function relationship of the coconut pericarp.

Sickness absence in female- and male-dominated occupations and workplaces.

PubMed

Mastekaasa, Arne

2005-05-01

Previous research suggests that both men's and women's level of sickness absence may be systematically related to the gender composition of their workplace as well as of their occupational category. The number of studies is, however, low and the composition of the occupational category has often been used as a proxy for the composition of the workplace. This paper employs a large data set broadly representative of the employed population of Norway. The data make it possible to take workplace and occupation simultaneously into account. Thus, the relationship between the gender composition of the workplace and sickness absence is estimated with detailed control for differences between occupational categories. Likewise, the importance of the gender composition of the occupation is assessed with control for between workplace variation. Men's sickness absence turns out to be largely unrelated to the gender composition of the workplace. For women the level of sickness absence tends to be higher in female-dominated workplaces, but the relationship is weak. These findings provide evidence against theories suggesting that the minority sex in the workplace faces special problems and is therefore more absent. They are to some extent consistent with the idea that female-dominated workplaces develop norms that are more tolerant towards sickness absence. The relationship of sickness absence to the gender composition of the occupational category is similar to the U-shaped pattern found in several previous studies (highest sickness absence both in strongly male-dominated and strongly female-dominated occupations), but again the relationship is weak.

Iron Isotope Systematics of the Bushveld Complex, South Africa: Initial Results

NASA Astrophysics Data System (ADS)

Stausberg, N.; Lesher, C. E.; Hoffmann-Barfod, G.; Glessner, J. J.; Tegner, C.

2014-12-01

Iron isotopes show systematic changes in igneous rocks that have been ascribed to fractional crystallization, partial melting, as well as, diffusion effects. Layered mafic intrusions, such as the Paleoproterozoic Bushveld Igneous Complex, are ideally suited to investigate stable isotope fractionation arising principally by fractional crystallization. The upper 2.1km of the Bushveld Complex (Upper and Upper Main Zone, UUMZ) crystallized from a basaltic magma produced by a major recharge event, building up a sequence of tholeiitic, Fe-rich, gabbroic cumulate rocks that display systematic variations in mineralogy and mineral compositions consistent with fractional crystallization. Within this sequence, magnetite joins the liquidus assemblage at ˜260m, followed by olivine at 460m and apatite at 1000m. Here, we present iron isotope measurements of bulk cumulate rocks from the Bierkraal drill core of UUMZ of the western limb. Iron was chemically separated from its matrix and analyzed for δ56Fe (relative to IRMM- 014) with a Nu plasma MC-ICPMS at the University of California, Davis, using (pseudo-) high resolution and sample-standard bracketing. The δ56Fe values for Bushveld cumulates span a range from 0.04‰ to 0.36‰, and systematically correlate with the relative abundance of pyroxene + olivine, magnetite and plagioclase. Notably, the highest δ56Fe values are found in plagioclase-rich cumulates that formed prior to magnetite crystallization. δ56Fe is also high in magnetite-rich cumulates at the onset of magnetite crystallization, while subsequent cumulates exhibit lower and variable δ56Fe principally reflecting fractionation of and modal variations in magnetite, pyroxene and fayalitic olivine. The overall relationships for δ56Fe are consistent with positive mineral - liquid Fe isotope fractionation factors for magnetite and plagioclase, and negative to near zero values for pyroxene and olivine. These initial results are being integrated into a forward model of the Bushveld liquid line of descent and will be compared to complementary work on the Skaergaard intrusion.

Magmatic Enclaves in Granitic Rocks: Paragons or Parasites?

NASA Astrophysics Data System (ADS)

Clemens, John; Stevens, Gary; Elburg, Marlina

2017-04-01

Granitic rocks form the fundamental building blocks of Earth's continents and provide us with a wide range of resources, so their formation is worth trying to understand. Fine-grained, igneous-textured microgranular enclaves of tonalitic to monzogranitic composition (ME) are common in granitic rocks and their origins have been hotly debated, with some workers suggesting that ME are not igneous. These ME have been studied intensively enough that we are now certain that they are of igneous origin - globules of mingled and quenched magma. Although a mantle connection is evident in many cases, their ultimate origin (including where in the lithosphere they originate) is still debated. This contribution explores the systematics of chemical variation in ME and their host granites, with the aim of uncovering any systematics in their behaviour and modelling the processes that have led to the variations that we measure, comparing host-rock series to their respective ME series. As always, the hope is that the study of ME may lead to improved understanding and modelling of the processes that are responsible for the formation of the host granitic magmas. Using variations between the molecular quantities Ti and M (Fe+Mn+Mg), we demonstrate that the petrogenetic processes that operated within a diverse group of S- and I-type granitic host magmas and their ME suites are dissimilar. Variations within the granitic series result from a variety of what might be called 'orderly' processes, resulting in linear or curvilinear trends in chemical variation diagrams. In contrast, processes that affected the ME series commonly resulted in scattered, chaotic variations. Even in cases in which an ME series displays more orderly variation, it can be shown that the hypothesis of simple mixing between a parent enclave magma and its host granitic magma, to produce the overall variations, cannot be supported. ME magmas had vastly smaller volumes compared with their host granitic magmas. Thus, they have commonly undergone hybridisation through mixing with deep crustal melts and both chemical and mechanical interactions with wall rocks and their host granitic magmas. As a result of this complex and chaotic set of processes, it remains extremely difficult to unravel the precise mechanisms that produced a given suite of ME magmas. Due to the similarities between the studied granites and their ME with occurrences worldwide, we suggest that our findings are likely to be generally applicable.

The Chemical Structure of the Hawaiian Mantle Plume

NASA Astrophysics Data System (ADS)

Ren, Z.; Hirano, N.; Hirata, T.; Takahashi, E.; Ingle, S.

2004-12-01

Numerous geochemical studies of Hawaiian basaltic lavas have shown that the Hawaiian mantle plume is isotopically heterogeneous. However, the distribution and scale of these heterogeneities remain unknown. This is essentially due to the complex interactions created by melting a heterogeneous source, subsequent aggregation of the melts on their way to the surface, and mixing that takes place in shallow magma chambers prior to eruption. In sum, the measured compositions of bulk lavas may represent only _eaverage_f compositions that do not fully reflect the complexity of either the mantle source heterogeneity and/or chemical structure. Melt inclusions, or samples of the local magma frozen in olivine phenocrysts during their formation, are better at recording the complex magmatic history than are the bulk samples. Here, we report major and trace element compositions of olivine-hosted melt inclusions from submarine Haleakala lavas that were collected by 2001-2002 JAMSTEC cruises measured by EPMA and LA-ICP-MS after homogenization at 1250° C, QFM for 20min. Melt inclusions from the submarine Hana Ridge (Haleakala volcano) show large ranges in CaO/Al2O3 (0.92-1.50), TiO2/Na2O (0.79-1.60) and Sr/Nb (14.56-36.60), Zr/Nb (6.48-16.95), ranging from Kilauea-like to Mauna Loa-like compositions within separately-sampled lavas as well as in a single host lava sample. Bulk rocks geochemistry shows that major element composition and trace element ratios such as Zr/Nb, Sr/Nb (Ren et al., 2004a, in press, J. Petrol.) together with Pb, Nd and Sr isotopic ratios (Ren et al., 2004b, submitted to J. Petrol.) of Haleakala shield volcano also display systematic compositional variation changing from a Kilauea-like in the submarine Hana Ridge (main shield stage) to Kilauea-Mauna Loa-like in the subaerial Honomanu stage (late shield stage, data from Chen and Frey, 1991). Some of the compositional variations in melt inclusions in single rocks are wider range than over-all variation observed in bulk rocks. It is important that both Kilauea-like and Mauna Loa-like compositions co-exist in melt inclusions in single submarine Hana Ridge rocks which are identified as Kilauea-like based on bulk geochemistry. These observations are inconsistent with the current interpretation that magma compositions are controlled by concentric zonation of the Hawaiian mantle plume (e.g. Kea component and Loa component), manifested as the Kea trend and the Loa trend volcanoes (e.g. Hauri, 1996; Lassiter et al., 1996). Our new data from olivine-hosted melt inclusions imply that the chemical structure of the Hawaiian mantle plume is significantly more complicated than previously modeled and the length-scale of chemical heterogeneity must be remarkably smaller than estimated based on bulk rock geochemistry.

Basaltic volcanism - The importance of planet size

NASA Technical Reports Server (NTRS)

Walker, D.; Stolper, E. M.; Hays, J. F.

1979-01-01

The volumetrically abundant basalts on the earth, its moon, and the eucrite parent planet all have chemical compositions that are controlled to a large extent by dry, low-pressure, crystal-liquid equilibria. Since this generalization is valid for these three planetary bodies, we infer that it may also apply to the other unsampled terrestrial planets. Other characteristics of basaltic volcanism show variations which appear to be related to planet size: the eruption temperatures, degrees of fractionation, and chemical variety of basalts and the endurance of basaltic volcanism all increase with planet size. Although the processes responsible for chemical differences between basalt suites are known, no simple systematization of the chemical differences between basalts from planet to planet has emerged.

Siderophile and chalcophile element abundances in oceanic basalts, Pb isotope evolution and growth of the earth's core

NASA Technical Reports Server (NTRS)

Newsom, H. E.; White, W. M.; Jochum, K. P.; Hofmann, A. W.

1986-01-01

The hypothesis that the mantle Pb isotope ratios reflect continued extraction of Pb into the earth's core over geologic time is evaluated by studying the depeletion of chalcophile and siderophile elements in the mantle. Oceanic basalt samples are analyzed in order to determine the Pb, Sr, and Nd isotropic compositions and the abundances of siderophile and chalcophile elements and incompatible lithophile elements. The data reveal that there is no systematic variation of siderophile or chalcophile element abundances relative to abundances of lithophile elements and the Pb/Ce ratio of the mantle is constant. It is suggested that the crust formation involves nonmagmatic and magmatic processes.

Categorial Compositionality II: Universal Constructions and a General Theory of (Quasi-)Systematicity in Human Cognition

PubMed Central

Phillips, Steven; Wilson, William H.

2011-01-01

A complete theory of cognitive architecture (i.e., the basic processes and modes of composition that together constitute cognitive behaviour) must explain the systematicity property—why our cognitive capacities are organized into particular groups of capacities, rather than some other, arbitrary collection. The classical account supposes: (1) syntactically compositional representations; and (2) processes that are sensitive to—compatible with—their structure. Classical compositionality, however, does not explain why these two components must be compatible; they are only compatible by the ad hoc assumption (convention) of employing the same mode of (concatenative) compositionality (e.g., prefix/postfix, where a relation symbol is always prepended/appended to the symbols for the related entities). Architectures employing mixed modes do not support systematicity. Recently, we proposed an alternative explanation without ad hoc assumptions, using category theory. Here, we extend our explanation to domains that are quasi-systematic (e.g., aspects of most languages), where the domain includes some but not all possible combinations of constituents. The central category-theoretic construct is an adjunction involving pullbacks, where the primary focus is on the relationship between processes modelled as functors, rather than the representations. A functor is a structure-preserving map (or construction, for our purposes). An adjunction guarantees that the only pairings of functors are the systematic ones. Thus, (quasi-)systematicity is a necessary consequence of a categorial cognitive architecture whose basic processes are functors that participate in adjunctions. PMID:21857816

Variation of stream temperature among mesoscale habitats within stream reaches: southern Appalachians

Treesearch

S. Lynsey Long; C. Rhett. Jackson

2014-01-01

Stream mesoscale habitats have systematic topographic relationships to hyporheic flow patterns, which may create predictable temperature variation between mesoscale habitat types. We investigated whether systematic differences in temperature metrics occurred between mesoscale habitats within reaches of small streams tributary to the upper Little Tennessee River,...

Bond length variation in Zn substituted NiO studied from extended X-ray absorption fine structure

NASA Astrophysics Data System (ADS)

Singh, S. D.; Poswal, A. K.; Kamal, C.; Rajput, Parasmani; Chakrabarti, Aparna; Jha, S. N.; Ganguli, Tapas

2017-06-01

Bond length behavior for Zn substituted NiO is determined through extended x-ray absorption fine structure (EXAFS) measurements performed at ambient conditions. We report bond length value of 2.11±0.01 Å for Zn-O of rock salt (RS) symmetry, when Zn is doped in RS NiO. Bond length for Zn substituted NiO RS ternary solid solutions shows relaxed behavior for Zn-O bond, while it shows un-relaxed behavior for Ni-O bond. These observations are further supported by first-principles calculations. It is also inferred that Zn sublattice remains nearly unchanged with increase in lattice parameter. On the other hand, Ni sublattice dilates for Zn compositions up to 20% to accommodate increase in the lattice parameter. However, for Zn compositions more than 20%, it does not further dilate. It has been attributed to the large disorder that is incorporated in the system at and beyond 20% of Zn incorporation in the cubic RS lattice of ternary solid solutions. For these large percentages of Zn incorporation, the Ni and the Zn atoms re-arrange themselves microscopically about the same nominal bond length rather than systematically increase in magnitude to minimize the energy of the system. This results in an increase in the Debye-Waller factor with increase in the Zn concentration rather than a systematic increase in the bond lengths.

THERMAL PHASE VARIATIONS OF WASP-12b: DEFYING PREDICTIONS

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

Cowan, Nicolas B.; Shekhtman, Louis M.; Machalek, Pavel

2012-03-01

We report Warm Spitzer full-orbit phase observations of WASP-12b at 3.6 and 4.5 {mu}m. This extremely inflated hot Jupiter is thought to be overflowing its Roche lobe, undergoing mass loss and accretion onto its host star, and has been claimed to have a C/O ratio in excess of unity. We are able to measure the transit depths, eclipse depths, thermal and ellipsoidal phase variations at both wavelengths. The large-amplitude phase variations, combined with the planet's previously measured dayside spectral energy distribution, are indicative of non-zero Bond albedo and very poor day-night heat redistribution. The transit depths in the mid-infrared-(R{sub p}more » /R{sub *}){sup 2} = 0.0123(3) and 0.0111(3) at 3.6 and 4.5 {mu}m, respectively-indicate that the atmospheric opacity is greater at 3.6 than at 4.5 {mu}m, in disagreement with model predictions, irrespective of C/O ratio. The secondary eclipse depths are consistent with previous studies: F{sub day}/F{sub *} = 0.0038(4) and 0.0039(3) at 3.6 and 4.5 {mu}m, respectively. We do not detect ellipsoidal variations at 3.6 {mu}m, but our parameter uncertainties-estimated via prayer-bead Monte Carlo-keep this non-detection consistent with model predictions. At 4.5 {mu}m, on the other hand, we detect ellipsoidal variations that are much stronger than predicted. If interpreted as a geometric effect due to the planet's elongated shape, these variations imply a 3:2 ratio for the planet's longest:shortest axes and a relatively bright day-night terminator. If we instead presume that the 4.5 {mu}m ellipsoidal variations are due to uncorrected systematic noise and we fix the amplitude of the variations to zero, the best-fit 4.5 {mu}m transit depth becomes commensurate with the 3.6 {mu}m depth, within the uncertainties. The relative transit depths are then consistent with a solar composition and short scale height at the terminator. Assuming zero ellipsoidal variations also yields a much deeper 4.5 {mu}m eclipse depth, consistent with a solar composition and modest temperature inversion. We suggest future observations that could distinguish between these two scenarios.« less

Iron isotope behavior during fluid/rock interaction in K-feldspar alteration zone - A model for pyrite in gold deposits from the Jiaodong Peninsula, East China

NASA Astrophysics Data System (ADS)

Zhu, Zhi-Yong; Jiang, Shao-Yong; Mathur, Ryan; Cook, Nigel J.; Yang, Tao; Wang, Meng; Ma, Liang; Ciobanu, Cristiana L.

2018-02-01

Mechanisms for Fe isotope fractionation in hydrothermal mineral deposits and in zones of associated K-feldspar alteration remain poorly constrained. We have analyzed a suite of bulk samples consisting of granite displaying K-feldspar alteration, Precambrian metamorphic rocks, and pyrite from gold deposits of the Jiaodong Peninsula, East China, by multi-collector inductively-coupled plasma mass spectrometry. Pyrites from disseminated (J-type) ores show a δ56Fe variation from +0.01 to +0.64‰, overlapping with the signature of the host granites (+0.08 to +0.39‰). In contrast, pyrites from quartz veins (L-type ores) show a wide range of Fe-isotopic composition from -0.78 to +0.79‰. Negative values are never seen in the J-type pyrites. The Fe isotope signature of the host granite with K-feldspar alteration is significantly heavier than that of the bulk silicate Earth. The Fe isotopic compositions of Precambrian metamorphic rocks across the district display a narrow range between -0.16‰ and +0.19‰, which is similar to most terrestrial rocks. Concentrations of major and trace elements in bulk samples were also determined, so as to evaluate any correlation between Fe isotope composition and degree of alteration. We note that during progressive K-feldspar alteration to rocks containing >70 wt% SiO2, >75 ppm Rb, and <1.2 wt% total Fe2O3, the Fe isotope composition of the granite changes systematically. The Fe isotope signature becomes heavier as the degree of alteration increases. The extremely light Fe isotopic compositions in L-type gold deposits may be explained by Rayleigh fractionation during pyrite precipitation in an open fracture system. We note that the sulfur isotopic compositions of pyrite in the two types of ores are also different. Pyrite from J-type ores has a systematically 3.5‰-higher δ34S value (11.2‰) than those of pyrite from the L-type ores (7.7‰). There is, however, no correlation between Fe and S isotope signatures. The isotopic fractionation of sulfur is used to constrain a change in the fO2 of the hydrothermal fluids from which pyrite precipitated. This work demonstrates that the Fe isotope composition of pyrite displays a significant response to the process of pyrite precipitation in hydrothermal systems, and that systematic fractionation of iron isotopes occurs during fluid/rock reaction in the K-feldspar alteration zone of the Linglong granite. The implications of the results are that processes of mineralization and associated fluid-rock interaction, which are ubiquitously observed in porphyry-style Cu-Au-Mo and other hydrothermal deposits, may be readily traceable using Fe isotopes.

Inventory of forest and rangeland and detection of forest stress

NASA Technical Reports Server (NTRS)

Heller, R. C.; Aldrich, R. C.; Weber, F. P.; Driscoll, R. S. (Principal Investigator)

1973-01-01

The author has identified the following significant results. At the Atlanta site (226B) it was found that bulk color composites for October 15, 1972, and April 13, 1973, can be interpreted together to disclose the location of the perennial Kudzu vine (Pyeraria lobata). Land managers concerned with Kudzu eradication could use ERTS-1 to inventory locations over 200 meters (660 feet) square. Microdensitometer data collected on ERTS-1 Bulk photographic products for the Manitou test site (226C) have shown that the 15-step gray-scale tablets are not of systematic equal values corresponding to 1/14 the maximum radiant energy incident on the MSS sensor. The gray-scale values present a third-order polynomial function rather than a direct linear relationship. Although data collected on step tablets for precision photographic products appear more discrete, the density variation within blocks in almost as great as variations between blocks. These system errors will cause problems when attempting to analyze radiometric variances among vegetation and land use classes.

Variation of anthocyanins and other major phenolic compounds throughout the ripening of four Portuguese blueberry (Vaccinium corymbosum L) cultivars.

PubMed

Silva, Sara; Costa, Eduardo M; Coelho, Marta C; Morais, Rui M; Pintado, Manuela E

2017-01-01

Blueberries are widely recognised as one of the richest sources of bioactive compounds, among which are anthocyanins, though the ripeness of berries has been reported as affecting the phytochemical composition of fruits. Therefore, the present work aimed to evaluate the variation of anthocyanins, and other major phenolics, throughout five ripening stages in four blueberry cultivars. The results showed that the antioxidant capacity and anthocyanin content increased during ripening, reaching the highest values when the blueberries are collected from bunches comprised of 75% ripe blueberries. Antagonistically, the amount of phenolic acid decreases, while the quercetin-3-glucoside levels remain stable. Furthermore, Goldtraube blueberries appear to possess, systematically, higher amounts of phenolic compounds than the other cultivars studied. Thus, when seeking the highest yield of anthocyanins, the preferred harvest should occur in bunches that contain ca 75% of ripe blueberries and, considering the cultivars assayed, the Goldtraube cultivar appears to be the richest in phenolic compounds.

Cu Isotopic Composition in Surface Environments and in Biological Systems: A Critical Review

PubMed Central

Wang, Zhuhong; Chen, Jiubin; Zhang, Ting

2017-01-01

Copper (Cu) is a transition metal and an essential micronutrient for organisms, but also one of the most widespread toxic inorganic contaminants at very high content. The research on Cu isotopes has grown rapidly in the last decade. Hitherto, a large number of studies have been published on the theoretical fractionation mechanisms, experimental data and natural variations of Cu isotopes in variable environments and ecosystems. These studies reported a large variation of δ65Cu (−16.49 to +20.04‰) in terrestrial samples and showed that Cu isotopes could be fractionated by various biogeochemical processes to different extent. Several papers have previously reviewed the coupling of Cu and Zn isotope systematics, and we give here a tentative review of the recent publications only on Cu isotopesin variable surface repositories, animals and human beings, with a goal to attract much attention to research on Cu (and other metals) behaviors in the environment and biological systems. PMID:28524094

An applied investigation of kenaf-based fiber/polymer composites as potential lightweight materials for automotive components

NASA Astrophysics Data System (ADS)

Du, Yicheng

Natural fibers have the potential to replace glass fibers in fiber-reinforced composite applications. However, the natural fibers' intrinsic properties cause these issues: (1) the mechanical property variation; (2) moisture uptake by natural fibers and their composites; (3) lack of sound, cost-effective, environment-friendly fiber-matrix compounding processes; (4) incompatibility between natural fibers and polymer matrices; and (5) low heat-resistance of natural fibers and their composites. This dissertation systematically studied the use of kenaf bast fiber bundles, obtained via a mechanical retting method, as a light-weight reinforcement material for fiber-reinforced thermoset polymer composites for automotive applications. Kenaf bast fiber bundle tensile properties were tested, and the effects of locations in the kenaf plant, loading rates, retting methods, and high temperature treatments and their durations on kenaf bast fiber bundle tensile properties were evaluated. A process has been developed for fabricating high fiber loading kenaf bast fiber bundle-reinforced unsaturated polyester composites. The generated composites possessed high elastic moduli and their tensile strengths were close to specification requirements for glass fiber-reinforced sheet molding compounds. Effects of fiber loadings and lengths on resultant composite's tensile properties were evaluated. Fiber loadings were very important for composite tensile modulus. Both fiber loadings and fiber lengths were important for composite tensile strengths. The distributions of composite tensile, flexural and impact strengths were analyzed. The 2-parameter Weibull model was found to be the most appropriate for describing the composite strength distributions and provided the most conservative design values. Kenaf-reinforced unsaturated polyester composites were also proved to be more cost-effective than glass fiber-reinforced SMCs at high fiber loadings. Kenaf bast fiber bundle-reinforced composite's water absorption properties were tested. Surface-coating and edge-sealing significantly reduced composite water resistance properties. Encapsulation was a practical method to improve composite water resistance properties. The molding pressure and styrene concentrations on composite and matrix properties were evaluated. Laser and plasma treatment improved fiber-to-matrix adhesion.

Errors in measurements by ultrasonic thickness gauges caused by the variation in ultrasonic velocity in constructional steels and metal alloys

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

Kalinin, V.A.; Tarasenko, V.L.; Tselser, L.B.

1988-09-01

Numerical values of the variation in ultrasonic velocity in constructional metal alloys and the measurement errors related to them are systematized. The systematization is based on the measurement results of the group ultrasonic velocity made in the All-Union Scientific-Research Institute for Nondestructive Testing in 1983-1984 and also on the measurement results of the group velocity made by various authors. The variations in ultrasonic velocity were systematized for carbon, low-alloy, and medium-alloy constructional steels; high-alloy iron base alloys; nickel-base heat-resistant alloys; wrought aluminum constructional alloys; titanium alloys; and cast irons and copper alloys.

Spatiotemporal variations in the abundance and composition of bulk and chromophoric dissolved organic matter in seasonally hypoxia-influenced Green Bay, Lake Michigan, USA.

PubMed

DeVilbiss, Stephen E; Zhou, Zhengzhen; Klump, J Val; Guo, Laodong

2016-09-15

Green Bay, Lake Michigan, USA, is the largest freshwater estuary in the Laurentian Great Lakes and receives disproportional terrestrial inputs as a result of a high watershed to bay surface area ratio. While seasonal hypoxia and the formation of "dead zones" in Green Bay have received increasing attention, there are no systematic studies on the dynamics of dissolved organic matter (DOM) and its linkage to the development of hypoxia. During summer 2014, bulk dissolved organic carbon (DOC) analysis, UV-vis spectroscopy, and fluorescence excitation-emission matrices (EEMs) coupled with PARAFAC analysis were used to quantify the abundance, composition and source of DOM and their spatiotemporal variations in Green Bay, Lake Michigan. Concentrations of DOC ranged from 202 to 571μM-C (average=361±73μM-C) in June and from 279 to 610μM-C (average=349±64μM-C) in August. In both months, absorption coefficient at 254nm (a254) was strongly correlated to bulk DOC and was most abundant in the Fox River, attesting a dominant terrestrial input. Non-chromophoric DOC comprised, on average, ~32% of bulk DOC in June with higher terrestrial DOM and ~47% in August with higher aquagenic DOM, indicating that autochthonous and more degraded DOM is of lower optical activity. PARAFAC modeling on EEM data resulted in four major fluorescent DOM components, including two terrestrial humic-like, one aquagenic humic-like, and one protein-like component. Variations in the abundance of DOM components further supported changes in DOM sources. Mixing behavior of DOM components also indicated that while bulk DOM behaved quasi-conservatively, significant compositional changes occurred during transport from the Fox River to the open bay. Copyright © 2016 Elsevier B.V. All rights reserved.

Analysing the isotopic life history of the alpine ungulates Capra ibex and Rupicapra rupicapra rupicapra through their horns.

PubMed

Barbosa, Inês C R; Kley, Maximiliane; Schäufele, Rudi; Auerswald, Karl; Schröder, Wolf; Filli, Flurin; Hertwig, Stefan; Schnyder, Hans

2009-08-01

The horn of ungulate grazers offers a valuable isotopic record of their diet and environment. However, there have been no reports of the spatio-temporal variation of the isotopic composition of horns. We investigated patterns of carbon (delta(13)C) and nitrogen (delta(15)N) isotopic composition along and perpendicular to the horn axis in Capra ibex and Rupicapra rupicapra rupicapra to assess the effects of animal age, within-year (seasonal) and inter-annual variation, natural contamination and sampling position on horn isotope composition. Horns of male C. ibex (n = 23) and R. r. rupicapra (n = 1) were sampled longitudinally on the front (only R. r. rupicapra) and back side and on the surface and sub-surface. The sides of the R. r. rupicapra horn did not differ in delta(13)C. In both species, the horn surface had a 0.15 per thousand lower delta(13)C and a higher carbon-to-nitrogen (C/N) ratio than the sub-surface. Washing the horn with water and organic solvents removed material that caused these differences. With age, the delta(15)N of C. ibex horns increased (+0.1 per thousand year(-1)), C/N ratio increased, and (13)C discrimination relative to atmospheric CO(2) ((13)Delta) increased slightly (+0.03 per thousand year(-1)). Geostatistical analysis of one C. ibex horn revealed systematic patterns of inter-annual and seasonal (13)C changes, but (15)N changed only seasonally. The work demonstrates that isotopic signals in horns are influenced by natural contamination (delta(13)C), age effects ((13)Delta and delta(15)N), and seasonal (delta(13)C and delta(15)N) and inter-annual variation (delta(13)C). The methods presented allow us to distinguish between these effects and thus allow the use of horns as isotopic archives of the ecology of these species and their habitat. Copyright (c) 2009 John Wiley & Sons, Ltd.

Unusual Iron Redox Systematics of Martian Magmas

NASA Technical Reports Server (NTRS)

Danielson, L.; Righter, K.; Pando, K.; Morris, R. V.; Graff, T.; Agresti, D.; Martin, A.; Sutton, S.; Newville, M.; Lanzirotti, A.

2012-01-01

Martian magmas are known to be FeO-rich and the dominant FeO-bearing mineral at many sites visited by the Mars Exploration rovers (MER) is magnetite. Morris et al. proposed that the magnetite appears to be igneous in origin, rather than of secondary origin. However, magnetite is not typically found in experimental studies of martian magmatic rocks. Magnetite stability in terrestrial magmas is well understood, as are the stabilities of FeO and Fe2O3 in terrestrial magmas. In order to better understand the variation of FeO and Fe2O3, and the stability of magnetite (and other FeO-bearing phases) in martian magmas, we have undertaken an experimental study with two emphases. First, we determine the FeO and Fe2O3 contents of super- and sub-liquidus glasses from a shergottite bulk composition at 1 bar to 4 GPa, and variable fO2. Second, we document the stability of magnetite with temperature and fO2 in a shergottite bulk composition.

Iron isotopic systematics of oceanic basalts

NASA Astrophysics Data System (ADS)

Teng, Fang-Zhen; Dauphas, Nicolas; Huang, Shichun; Marty, Bernard

2013-04-01

The iron isotopic compositions of 93 well-characterized basalts from geochemically and geologically diverse mid-ocean ridge segments, oceanic islands and back arc basins were measured. Forty-three MORBs have homogeneous Fe isotopic composition, with δ56Fe ranging from +0.07‰ to +0.14‰ and an average of +0.105 ± 0.006‰ (2SD/√n, n = 43, MSWD = 1.9). Three back arc basin basalts have similar δ56Fe to MORBs. By contrast, OIBs are slightly heterogeneous with δ56Fe ranging from +0.05‰ to +0.14‰ in samples from Koolau and Loihi, Hawaii, and from +0.09‰ to +0.18‰ in samples from the Society Islands and Cook-Austral chain, French Polynesia. Overall, oceanic basalts are isotopically heavier than mantle peridotite and pyroxenite xenoliths, reflecting Fe isotope fractionation during partial melting of the mantle. Iron isotopic variations in OIBs mainly reflect Fe isotope fractionation during fractional crystallization of olivine and pyroxene, enhanced by source heterogeneity in Koolau samples.

Nature and origin of the sedimentary pile subducting in the Nankai Through

NASA Astrophysics Data System (ADS)

Chauvel, C.; Garcon, M.; Yobregat, E.; Chipoulet, C.; Labanieh, S.

2013-12-01

Nd-Hf isotopes and trace and major element concentrations were measured on bulk sediments recovered at Site C0012 during IODP Expedition 322 and 333 in the Shikoku basin. We analyzed the composition of different lithologies such as clay, claystone, sand, sandstone, and ash layers, all through the sedimentary pile, from the surface to the sediment-basalt interface, in order to identify compositional trends and source variations with depth. Major and trace element contents of the background sediments (hemipelagic mudstone) are very homogenous and span a relatively small range of values throughout the entire sedimentary pile. Their composition resembles that of the average upper continental crust of Rudnick and Gao (2003, Treatise on Geochemistry, Vol.3, p. 1-64). Nd and Hf isotopes are more variable, relatively unradiogenic (-8 < ɛNd < -3 ; -4 < ɛHf < +5) but display no systematic variations with depth (Fig. 1). Such isotopic compositions indicate that the background sedimentation of the Shikoku basin may consist of volcaniclastic material from the Izu-Bonin and/or Ryukyu arcs, detrital material eroded from SW Japan and relatively high amount of an evolved continental-derived component, probably Chinese loess as already suggested by Mahomet (2005, Sediment. Geol., 182, p.183-199). Compared to the background sedimentation, volcanic ash layers and volcaniclastic sandstones have very different trace element patterns and more radiogenic Nd-Hf isotopic signature (Fig. 1). Our results allow us to distinguish at least two different volcanic sources for these deposits. At the bottom of the sedimentary pile, siliciclastic sandstones with a mid-Miocene age are present; they have remarkably low ɛNd and ɛHf values (i.e. ɛNd < -8 and ɛHf < -5). Such isotopic compositions clearly demonstrate that their source cannot be the Japanese mainland, as suggested by previous studies (e.g. Underwood et al, 2009, Exp.322 PR ; Fergusson, 2003, Proc. ODP, Sci. Results 190/196). These sandstones are also too coarse to result from an accumulation of Chinese loess transported by wind (particles usually finer than 40 μm). Given the location of the Shikoku basin at 15Ma, we suggest that the siliciclastic sandstones mainly consists of detrital materials transported by Chinese rivers up to the sea in the Shikoku basin. Variations of ɛNd as a function of depth. Potential sediment sources are indicated by color bands

Trace elements in natural azurite pigments found in illuminated manuscript leaves investigated by synchrotron x-ray fluorescence and diffraction mapping

NASA Astrophysics Data System (ADS)

Smieska, Louisa M.; Mullett, Ruth; Ferri, Laurent; Woll, Arthur R.

2017-07-01

We present trace-element and composition analysis of azurite pigments in six illuminated manuscript leaves, dating from the thirteenth to sixteenth century, using synchrotron-based, large-area x-ray fluorescence (SR-XRF) and diffraction (SR-XRD) mapping. SR-XRF mapping reveals several trace elements correlated with azurite, including arsenic, zirconium, antimony, barium, and bismuth, that appear in multiple manuscripts but were not always detected by point XRF. Within some manuscript leaves, variations in the concentration of trace elements associated with azurite coincide with distinct regions of the illuminations, suggesting systematic differences in azurite preparation or purification. Variations of the trace element concentrations in azurite are greater among different manuscript leaves than the variations within each individual leaf, suggesting the possibility that such impurities reflect distinct mineralogical/geologic sources. SR-XRD maps collected simultaneously with the SR-XRF maps confirm the identification of azurite regions and are consistent with impurities found in natural mineral sources of azurite. In general, our results suggest the feasibility of using azurite trace element analysis for provenance studies of illuminated manuscript fragments, and demonstrate the value of XRF mapping in non-destructive determination of trace element concentrations within a single pigment.

Local band gap measurements by VEELS of thin film solar cells.

PubMed

Keller, Debora; Buecheler, Stephan; Reinhard, Patrick; Pianezzi, Fabian; Pohl, Darius; Surrey, Alexander; Rellinghaus, Bernd; Erni, Rolf; Tiwari, Ayodhya N

2014-08-01

This work presents a systematic study that evaluates the feasibility and reliability of local band gap measurements of Cu(In,Ga)Se2 thin films by valence electron energy-loss spectroscopy (VEELS). The compositional gradients across the Cu(In,Ga)Se2 layer cause variations in the band gap energy, which are experimentally determined using a monochromated scanning transmission electron microscope (STEM). The results reveal the expected band gap variation across the Cu(In,Ga)Se2 layer and therefore confirm the feasibility of local band gap measurements of Cu(In,Ga)Se2 by VEELS. The precision and accuracy of the results are discussed based on the analysis of individual error sources, which leads to the conclusion that the precision of our measurements is most limited by the acquisition reproducibility, if the signal-to-noise ratio of the spectrum is high enough. Furthermore, we simulate the impact of radiation losses on the measured band gap value and propose a thickness-dependent correction. In future work, localized band gap variations will be measured on a more localized length scale to investigate, e.g., the influence of chemical inhomogeneities and dopant accumulations at grain boundaries.

Geographic variation in left ventricular mass and mass index: a systematic review.

PubMed

Poppe, K K; Bachmann, M Edgerton; Triggs, C M; Doughty, R N; Whalley, G A

2012-07-01

Left ventricular (LV) hypertrophy, defined as an abnormal increase in LV mass (LVM), is an important prognostic indicator and therapeutic target. LVM is often divided by body surface area to derive indexed mass; however, this does not correctly identify pathological LV hypertrophy in all people, especially when body composition is altered, or in different ethnic groups. We evaluated published ranges of echocardiographic LVM in healthy adult populations from different countries, excluding control groups, and compared them with the American Society of Echocardiography reference ranges. A total of 33 studies met the inclusion criteria. In men and women, there was wide variation in the ranges of LVM with a tendency for the upper limit to increase geographically westward; this variation remained for indexed mass. Several ranges fell outside the upper reference limits: in men, 13 of the mass ranges and 16 of indexed mass; and in women, 8 mass and 16 indexed mass. This review has shown that current guidelines may need revision as some published series suggest that greater LV mass should be considered normal. This may be explained by ethnic differences and supports the need for widely applicable and ethnically diverse reference ranges to be established.

Evaporation/SST Sensitivity Over the Tropical Oceans During ENSO Events as Estimated from the da Silva, Young, Levitus Surface Marine Data Set

NASA Technical Reports Server (NTRS)

Robertson, F. R.; Fitzjarrald, D. E.; Sohn, B.-J.; Arnold, James E. (Technical Monitor)

2001-01-01

The da Silva, Young and Levitus Surface Marine Atlas, based on observations from the Comprehensive Ocean Atmosphere Data Set (COADS) Release 1, has been used to investigate the relationship between evaporation and sea-surface temperature (SST) over the global oceans. For the period 1950 to 1987 SST, surface latent heat flux, and other related variables have been filtered to minimize data uncertainties and to focus upon interannual variations associated with warm (El Nino) and cold (La Nina) ENSO events. Compositing procedures have enabled identification of systematic variations in latent heat fluxes accompanying these events and the relationship to spatial anomalies in ocean surface wind speed and humidity. The evaporation response associated with ENSO sea surface temperature (SST) variability is systematic in nature and composed of offsetting contributions from the surface wind and humidity variations. During warm events exceeding 1.0 S.D. delta SST, increases in the surface humidity deficit, delta(qs-qa), between the surface and 2m height dominate regions of positive SST anomalies and lead to increases in evaporation of almost 2 Wm (exp -2) at deltaSST = 0.23 K. Despite the increases in specific humidity, relative humidity decreases slightly in regions of elevated SSTs. For the most part, variations in wind speed are consistent with previous investigations. Weakening of the equatorial easterlies (and generation of westerlies) between 160 degrees E and 140 degrees W dominates during the early phases of warm events. Elevated wind speeds in adjacent subtropical regions and in the eastern equatorial Pacific subsequently develop too. The net contribution of these winds, which reflect adjustments in Hadley and Walker circulation components is toward reduced evaporation. Results for cold periods are approximately similar, but opposite in sign to warm events, though evidence of different temporal evolution is noted.

Magmatic processes in the layered Series of the Skaergaard intrusion inferred from core and rim compositions of plagioclase

NASA Astrophysics Data System (ADS)

Brown, W. L.; Toplis, M. J.

2003-04-01

Due to slow NaSi-CaAl exchange in plagioclase, the proportion of the anorthite component (An) may be considered essentially a primary feature in magmatic bodies such as small layered intrusions. Thus, An provides a potential window into the evolution of such magmatic systems on various length scales. In order to assess the utility of this approach, 13 thin sections covering the principal zones and sub-zones of the Layered Series of the Skaergaard intrusion, East Greenland, were studied. In each thin section 90 to 150 analyses of plagioclase were made using an electron microprobe. Analyses were made in grain centres and at grain edges, particular attention being paid to plagioclase-plagioclase contacts. The cores of large and moderately sized crystals show narrow compositional ranges, 90% of analyses lying within 3 mol% of the mean. In accordance with previous studies, we find that mean core compositions vary continuously with stratigraphic height, from ˜An70 at the lowest levels, to ˜An30 at the top of Upper Zone (UZ). Rim compositions of touching plagioclase also show strong maxima in their mode, but the variation of this composition with stratigraphic height is distinctly different from that of crystal cores. In the Lower Zone (LZ) and lower Middle Zone (MZ), the most abundant rim compositions are systematically An50± 1, core and rim compositions converging in the lower MZ. In the upper MZ to UZ, rim compositions are very similar to corresponding cores, but locally may be more evolved, particularly when plagioclase is intergrown with quartz. The systematic decrease of An as a function of stratigraphic height is strong evidence in favour of fractional crystallization of the main liquid. However, the fact that plagioclase zoning does not extend to nearly pure albite in the vast majority of rocks implies mobility of intercumulus liquid. If compaction (expulsion) were the mechanism responsible for this, it would be difficult to explain the remarkably constant cut-off in rim compositions at An50 in the LZ and lower MZ. On the other hand, this cut-off corresponds to the An content at magnetite saturation, which leads us to propose that the observed features are the result of a density inversion in the liquid following oxide saturation. This density inversion causes the intercumulus liquid to become gravitationally unstable relative to the overlying main liquid leading to compositional convection in the upper LZ and MZ, a hypothesis consistent with the adcumulus texture of those rocks.

Soil resources and topography shape local tree community structure in tropical forests

PubMed Central

Baldeck, Claire A.; Harms, Kyle E.; Yavitt, Joseph B.; John, Robert; Turner, Benjamin L.; Valencia, Renato; Navarrete, Hugo; Davies, Stuart J.; Chuyong, George B.; Kenfack, David; Thomas, Duncan W.; Madawala, Sumedha; Gunatilleke, Nimal; Gunatilleke, Savitri; Bunyavejchewin, Sarayudh; Kiratiprayoon, Somboon; Yaacob, Adzmi; Supardi, Mohd N. Nur; Dalling, James W.

2013-01-01

Both habitat filtering and dispersal limitation influence the compositional structure of forest communities, but previous studies examining the relative contributions of these processes with variation partitioning have primarily used topography to represent the influence of the environment. Here, we bring together data on both topography and soil resource variation within eight large (24–50 ha) tropical forest plots, and use variation partitioning to decompose community compositional variation into fractions explained by spatial, soil resource and topographic variables. Both soil resources and topography account for significant and approximately equal variation in tree community composition (9–34% and 5–29%, respectively), and all environmental variables together explain 13–39% of compositional variation within a plot. A large fraction of variation (19–37%) was spatially structured, yet unexplained by the environment, suggesting an important role for dispersal processes and unmeasured environmental variables. For the majority of sites, adding soil resource variables to topography nearly doubled the inferred role of habitat filtering, accounting for variation in compositional structure that would previously have been attributable to dispersal. Our results, illustrated using a new graphical depiction of community structure within these plots, demonstrate the importance of small-scale environmental variation in shaping local community structure in diverse tropical forests around the globe. PMID:23256196

Os isotope systematics of La Palma, Canary Islands: Evidence for recycled crust in the mantle source of HIMU ocean islands

NASA Astrophysics Data System (ADS)

Marcantonio, Franco; Zindler, Alan; Elliott, Tim; Staudigel, Hubert

1995-07-01

Sub-aerial lavas from the single ocean island of La Palma, Canary Islands show as large a variation in 187Os/186Os isotope ratios (1.13-1.59) as found across all of French Polynesia [1]. The La Palma lavas, however, display a restricted range of chemical composition and have all been erupted within the last 3.5 Ma. The highest Os isotopic compositions are observed in lavas with low Os concentrations. An uplifted sequence of lavas, that represent the early phase of submarine growth of the island, show extremely heterogeneous 187Os/186Os isotope ratios, from 1.21 to 3.53, with the most radiogenic values found in pillow rinds. Assimilation of these pillow rinds by ascending magma can readily account for highly radiogenic ratios ( 187Os/186Os > 1.3 ) found in lavas with Os concentrations below 30 ppt. Samples with Os concentrations too high to be significantly affected by assimilation still display a range in Os isotope ratios from 1.13 to 1.25. We argue that these radiogenic values reflect a HIMU mantle source that contains ancient recycled oceanic crust. Characteristic incompatible trace element ratios suggest further similarities between the mantle beneath La Palma and other HIMU islands. When potentially contaminated low-Os OIBs are screened from literature data, HIMU islands are found to display the highest Os isotope ratios (up to 1.25). PbOs systematics for uncontaminated OIBs do not define a simple two-component mixing relationship between ambient mantle and recycled oceanic crust of a single composition. We suggest that this is due to variable alteration and subduction-induced perturbation of the U/Pb ratio in the recycled material that forms a component of the HIMU source.

INVESTIGATION OF SYSTEMATIC EFFECTS IN KEPLER DATA: SEASONAL VARIATIONS IN THE LIGHT CURVE OF HAT-P-7b

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

Van Eylen, V.; Lindholm Nielsen, M.; Hinrup, B.

2013-09-10

With years of Kepler data currently available, the measurement of variations in planetary transit depths over time can now be attempted. To do so, it is of primary importance to understand which systematic effects may affect the measurement of transits. We aim to measure the stability of Kepler measurements over years of observations. We present a study of the depth of about 500 transit events of the Hot Jupiter HAT-P-7b, using 14 quarters (Q0-Q13) of data from the Kepler satellite. We find a systematic variation in the depth of the primary transit, related to quarters of data and recurring yearly.more » These seasonal variations are about 1%. Within seasons, we find no evidence for trends. We speculate that the cause of the seasonal variations could be unknown field crowding or instrumental artifacts. Our results show that care must be taken when combining transits throughout different quarters of Kepler data. Measuring the relative planetary radius of HAT-P-7b without taking these systematic effects into account leads to unrealistically low error estimates. This effect could be present in all Kepler targets. If so, relative radius measurements of all Hot Jupiters to a precision much better than 1% are unrealistic.« less

The Diversity of Anomalous HEDs: Isotopic Constraints on the Connection of EET 92023, GRA 98098, and Dhofar 700 With Vesta

NASA Technical Reports Server (NTRS)

Sanborn, M. E.; Yin, Q.-Z.; Mittlefehldt, D. W.

2016-01-01

The possibility for multiple parent bodies, instead of a common parent body of Vesta, for eucrites has been suggested based on the variable oxygen isotopic composition observed in some eucrites.. Recently, we added an extra dimension to the discussion based on the (epsilon)54Cr composition of the same eucrites with known (delta)17O to compare with the normal eucrites. The combined (delta)17O and (epsilon)54Cr isotope systematics for Pasamonte, PCA 91007, A-881394, and Ibitira indicate their likely origin from multiple different parent bodies than the normal eucrites. Often the qualifier anomalous is used to identify HEDs with (delta)17O values that deviate significantly (>3(sigma)) from the mean HED (delta)17O. However, variations in eucrites and diogenites also include unique geochemical characteristics such as bulk composition, trace element abundances, or volatile concentrations, in addition to (delta)17O. Here, we investigate three such geochemically anomalous HEDs: Elephant Moraine (EET) 92023, Graves Nunataks (GRA) 98098, and Dhofar 700. In addition, to verify the homogeneity of (epsilon)54Cr observed for normal HEDs thus far, a set of seven eucrites and diogenites considered normal samples were also investigated.

Ferroelectric properties of PbxSr1-xTiO3 and its compositionally graded thin films grown on the highly oriented LaNiO3 buffered Pt /Ti/SiO2/Si substrates

NASA Astrophysics Data System (ADS)

Zhai, Jiwei; Yao, Xi; Xu, Zhengkui; Chen, Haydn

2006-08-01

Thin films of ferroelectric PbxSr1-xTiO3 (PST) with x =0.3-0.7 and graded composition were fabricated on LaNiO3 buffered Pt /Ti/SiO2/Si substrates by a sol-gel deposition method. The thin films crystallized into a single perovskite structure and exhibited highly (100) preferred orientation after postdeposition annealing at 650°C. The grain size of PST thin films systematically decreased with the increase of Sr content. Dielectric and ferroelectric properties were investigated as a function of temperature, frequency, and dc applied field. Pb0.6Sr0.4TiO3 films showed a dominant voltage dependence of dielectric constant with a high tunability in a temperature range of 25-230°C. The compositionally graded PST thin films with x =0.3-0.6 also showed the high tunability. The graded thin films exhibited a diffused phase transition accompanied by a diffused peak in the temperature variations of dielectric constants. This kind of thin films has a potential in a fabrication of a temperature stable tunable device.

Thorium and uranium variations in Apollo 17 basalts, and K-U systematics

NASA Technical Reports Server (NTRS)

Laul, J. C.; Fruchter, J. S.

1976-01-01

It is found that Apollo 11 low-K and in particular Apollo 17 mare basalts show a wide range of Th/U ratios unlike other rocks; such variations cannot be explained by near surface crystal fractionation. A two-stage fractional crystallization-partial melting model involving a clinopyroxene cumulate as the major phase can explain the variations in Th/U ratios. Due to the Sm-Nd systematics constraint, several source cumulates are invoked to explain the observed Th/U continuum.

Compositional Variation in Magmas Supplied to the Southern East Pacific Rise, 17°-19° S: Implications for Magma Reservoir Dynamics

NASA Astrophysics Data System (ADS)

Bergmanis, E. C.; Sinton, J. M.; Rubin, K. H.; Gregg, T. K.; Cormier, M.

2002-12-01

Fine-scale observation and sampling of lavas from the southern EPR 17°-19° S reveal both short- and long-term compositional heterogeneity of flows produced in single eruptive episodes. Located between 17° 24' and 17° 36'S, the 140 x 106 m2 Aldo-Kihi flow reaches a maximum width of 2.2 km between 17° 26' and 17° 28'S; the presence of sheet flows, lava channels, and summit collapse troughs imply that the eruption was centered in this area of broad axial morphology. Some lava channels and collapsed lava tubes extend beyond the margins of the recently erupted Aldo-Kihi flow, indicating that lava distribution systems can persist over at least several hundreds of years and multiple separate eruptions were apparently centered in this region. Extensive glass analyses of the Aldo-Kihi flow show that MgO contents range from 7.7-8.4 wt %; all the samples with greater than 8.0 wt % MgO occur south of 17° 30'S. This result is hard to reconcile with along-axis propagation of a single dike, and suggests vertical eruption from a magma chamber that is compositionally zoned along-axis. Twenty-three other samples older than Aldo-Kihi contain > 8.0 wt % MgO; all but two occur south of 17° 28.4'S suggesting that the displacement of eruptive centers from the location of hottest subaxial magma is a long-lived feature of this region. Lack of compositional variation across some contacts indicates that this length of ridge has erupted compositionally similar lavas in separate volcanic episodes. Elsewhere distinctly different lava compositions include the several-hundred-year-old Rehu-Marka Fe-Ti basalt, and local occurrences of incompatible element-enriched T-MORB. The distribution of rock types in this area requires a complex history of mantle melting, recharge, cooling, and eruption that has been spatially systematic over time scales encompassing several eruptive episodes. Between 18° 31.5' and 18° 34.5'S the South Hump lava is distinctly bimodal with highly evolved ferrobasalts (MgO < 6.2 wt %, Na2O < 3.1 wt %) in the south, and basalts (~7.2 wt % MgO, Na2O > 3.1 wt %) in the north. Major and trace element data for these lavas indicate that they cannot be related by low-pressure fractional crystallization and that variations in mantle source composition appears to be required to explain the observed compositional variation. Existing geological evidence indicates that either the axial graben here was resurfaced by a single, chemically bimodal eruption, or by two adjacent eruptions that must be close in age. The boundary between the two chemical types corresponds to discontinuities in the axial magma chamber imaged by seismic reflection, as well as to significant differences in the thickness of seismic layer 2A. This result indicates that magma arising from vastly different melting processes can reside in adjacent crustal magma reservoirs and be tapped, either during a single eruption or during closely spaced eruptions in adjacent regions.

Compositional modes in the ash fraction of some modern pyroclastic deposits: their determination and significance

NASA Astrophysics Data System (ADS)

De Rosa, R.

This paper illustrates some problems involved in the quantitative compositional study of pyroclastic deposits and proposes criteria for selecting the main petrographic and textural classes for modal analysis. The relative proportions of the different classes are obtained using a point-counting procedure applied to medium-coarse ash samples that reduces the dependence of the modal composition on grain size and avoids tedious counting of different grain-size fractions. The major purposes of a quantified measure of component distributions are to: (a) document the nature of the fragmenting magma; (b) define the eruptive dynamics of the eruptions on a detailed scale; and (c) ensure accuracy in classifying pyroclastic deposits. Compositional modes of the ash fraction of pyroclastic deposits vary systematically, and their graphical representation defines the compositional and textural characteristics of pyroclastic fragments associated with different eruptive styles. Textural features of the glass component can be very helpful for inferring aspects of eruptive dynamics. Four major parameters can be used to represent the component composition of pyroclastic ash deposits: (a) juvenile index (JI); (b) crystallinity index (CrI); (c) juvenile vesicularity index (JVI); and (d) free crystal index (FCrI). The FCrI is defined as the ratio between single and total crystal fragments in the juvenile component (single crystals+crystals in juvenile glass). This parameter may provide an effective estimate of the mechanical energy of eruptions. Variations in FCrI vs JVI discriminate among pyroclastic deposits of different origin and define compositional fields that represent ash derived from different fragmentation styles.

Zinc Isotopic Signatures of the Upper Continental Crust

NASA Astrophysics Data System (ADS)

Xia, Y.; Zhang, X.; Zhang, H.; Huang, F.

2016-12-01

To examine the Zn isotope systematics within the Upper Continental Crust (UCC), and isotope fractionation during chemical weathering in large spatial and temporal scales, we analyzed Zn isotopic compositions of loess, glacial diamictites, river sediments, and igneous rocks (samples in total 77). The Zn isotopic compositions (δ66Zn relative to JMC-Lyon) of loess display a limited variation (0.17‰ to 0.29‰), which is negatively correlated with Zn content and proxies for chemical weathering (e.g. CIA values), reflect the impact of chemical weathering. Glacial diamictites have more variable δ66Zn (0.09‰ to 0.48‰), but the average δ66Zn (0.29±0.03‰, 2SD) is similar to loess. δ66Zn of glacial diamictites correlate roughly negatively with CIA values, but have no correlation with Zn content, implying source heterogeneity and effect from chemical weathering. δ66Zn of A-type (0.39‰ to 0.45‰) and S-type (0.28‰ to 0.35‰) granites are both homogeneous, but the latter have systematically lighter δ66Zn. This may reflect no Zn isotopic fractionation during magmatic processes and involvement of isotopically light meta-sedimentary into the sources of S-type granites. Furthermore, δ66Zn in riverine sediments display a small variation from 0.23‰ to 0.37‰, while δ66Zn of the the shales vary from 0.14‰ to 0.53‰, which could result from a combination of processes, such as biological cycling and chemical weathering. Overall, our data suggest that incipient chemical weathering can fractionate Zn isotopes significantly, meanwhile, during this process, heavy Zn are released preferentially. The UCC is estimated to have an average δ66Zn of 0.30 ±0.03‰ (2SD) with data collected in this study, which is similar to the estimated value of Bulk Silicate Earth (0.28±0.05‰)[1] and mean dissolved riverine flux (0.33‰)[2], but distinctly lighter than the bulk composition of dissolved Zn in the ocean (0.51‰)[2]. [1] Chen et al., Zinc isotope fractionation during magmatic differentiation and the isotopic composition of the bulk Earth. Earth and Planetary Science Letters 369, 34-42 (2013). [2] Little et al., The oceanic mass balance of copper and zinc isotopes, investigated by analysis of their inputs, and outputs to ferromanganese oxide sediments. Geochimica et Cosmochimica Acta 125, 673-693 (2014).

Effects of Fertile Mantle Compositional Variation and Spreading Rate Variation on the Working of Global Ocean Ridges

NASA Astrophysics Data System (ADS)

Niu, Y.; O'Hara, M. J.

2014-12-01

Mantle temperature variation, plate spreading rate variation and mantle compositional variation have been considered to be the three fundamental variables that govern the working of global ocean ridges [1]. An analysis demonstrates that mantle compositional variation exerts the primary control on ocean ridge processes; it determines (1) variation in both composition and mode of mantle mineralogy, (2) variation of mantle density, (3) variation of ridge axial depth, (4) source-inherited MORB compositional variation, (4) density-controlled variation in the amplitude of mantle upwelling, (5) apparent variation in the extent of melting, and (6) the correlated variation of MORB chemistry with ridge axial depth [2]. The above interpretations are reinforced by the updated MORB database [3]. The new database also confirms spreading rate control on the extent of melting as shown previously [4]. Mantle temperature variation could play a part, but its overstated role [3,5] results from a basic error (1) in treating ridge axial depth variation as evidence of mantle temperature variation by ignoring the intrinsic control of mantle composition, (2) in treating "mantle plume" influenced ridges (e.g., Iceland) as normal ridges of plate spreading origin, and (3) in treating low Vs at greater depths (> 300 km vs. < 200 km beneath ridges) beneath these "mantle plume" influenced ridges as evidence for hot ridge mantle. In order to understand the working of global ocean ridges, we must avoid plume-influenced ridges (e.g., in the vicinity of Iceland) and remove/average out data from such ridges. As a result, the correlations (e.g., between ridge axial depth, mantle low Vs anomaly, and some geochemical parameters) required for the interpretation of mantle temperature control all disappear. There is thus no evidence for large mantle temperature variation away from ridges influenced by "mantle plumes". References: [1] Niu et al., 2001, Earth Planet Sci. Lett., 186, 383-399; [2] Niu & O'Hara, 2008, J. Petrol., 49, 633-664; [3] Gale et al., 2014, J. Petrol, 55, 1051-1082; [4] Niu & Hékinian, 1997, Nature, 385, 326-329; [5] Dalton et al., 2014, Science, 334, 80-83; [6]Niu & Hékinian, 2004, In Oceanic Hotspots, Springer-Verlag, 285-307.

Sensitivity of grassland plant community composition to spatial vs. temporal variation in precipitation

USDA-ARS?s Scientific Manuscript database

Climate gradients shape spatial variation in the richness and composition of plant communities. Given future predicted changes in climate means and variability, and likely regional variation in the magnitudes of these changes, it is important to determine how temporal variation in climate influences...

Identification and Modelling of the In-Plane Reinforcement Orientation Variations in a CFRP Laminate Produced by Manual Lay-Up

NASA Astrophysics Data System (ADS)

Davila, Yves; Crouzeix, Laurent; Douchin, Bernard; Collombet, Francis; Grunevald, Yves-Henri

2017-08-01

Reinforcement angle orientation has a significant effect on the mechanical properties of composite materials. This work presents a methodology to introduce variable reinforcement angles into finite element (FE) models of composite structures. The study of reinforcement orientation variations uses meta-models to identify and control a continuous variation across the composite ply. First, the reinforcement angle is measured through image analysis techniques of the composite plies during the lay-up phase. Image analysis results show that variations in the mean ply orientations are between -0.5 and 0.5° with standard deviations ranging between 0.34 and 0.41°. An automatic post-treatment of the images determines the global and local angle variations yielding good agreements visually and numerically between the analysed images and the identified parameters. A composite plate analysed at the end of the cooling phase is presented as a case of study. Here, the variation in residual strains induced by the variability in the reinforcement orientation are up to 28% of the strain field of the homogeneous FE model. The proposed methodology has shown its capabilities to introduce material and geometrical variability into FE analysis of layered composite structures.

Identification and Modelling of the In-Plane Reinforcement Orientation Variations in a CFRP Laminate Produced by Manual Lay-Up

NASA Astrophysics Data System (ADS)

Davila, Yves; Crouzeix, Laurent; Douchin, Bernard; Collombet, Francis; Grunevald, Yves-Henri

2018-06-01

Reinforcement angle orientation has a significant effect on the mechanical properties of composite materials. This work presents a methodology to introduce variable reinforcement angles into finite element (FE) models of composite structures. The study of reinforcement orientation variations uses meta-models to identify and control a continuous variation across the composite ply. First, the reinforcement angle is measured through image analysis techniques of the composite plies during the lay-up phase. Image analysis results show that variations in the mean ply orientations are between -0.5 and 0.5° with standard deviations ranging between 0.34 and 0.41°. An automatic post-treatment of the images determines the global and local angle variations yielding good agreements visually and numerically between the analysed images and the identified parameters. A composite plate analysed at the end of the cooling phase is presented as a case of study. Here, the variation in residual strains induced by the variability in the reinforcement orientation are up to 28% of the strain field of the homogeneous FE model. The proposed methodology has shown its capabilities to introduce material and geometrical variability into FE analysis of layered composite structures.

Metabolite profiling of Clinacanthus nutans leaves extracts obtained from different drying methods by 1H NMR-based metabolomics

NASA Astrophysics Data System (ADS)

Hashim, Noor Haslinda Noor; Latip, Jalifah; Khatib, Alfi

2016-11-01

The metabolites of Clinacanthus nutans leaves extracts and their dependence on drying process were systematically characterized using 1H nuclear magnetic resonance spectroscopy (NMR) multivariate data analysis. Principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA) were able to distinguish the leaves extracts obtained from different drying methods. The identified metabolites were carbohydrates, amino acid, flavonoids and sulfur glucoside compounds. The major metabolites responsible for the separation in PLS-DA loading plots were lupeol, cycloclinacosides, betulin, cerebrosides and choline. The results showed that the combination of 1H NMR spectroscopy and multivariate data analyses could act as an efficient technique to understand the C. nutans composition and its variation.

A change in the geodynamics of continental growth 3 billion years ago.

PubMed

Dhuime, Bruno; Hawkesworth, Chris J; Cawood, Peter A; Storey, Craig D

2012-03-16

Models for the growth of continental crust rely on knowing the balance between the generation of new crust and the reworking of old crust throughout Earth's history. The oxygen isotopic composition of zircons, for which uranium-lead and hafnium isotopic data provide age constraints, is a key archive of crustal reworking. We identified systematic variations in hafnium and oxygen isotopes in zircons of different ages that reveal the relative proportions of reworked crust and of new crust through time. Growth of continental crust appears to have been a continuous process, albeit at variable rates. A marked decrease in the rate of crustal growth at ~3 billion years ago may be linked to the onset of subduction-driven plate tectonics.

The effect of processing and compositional changes on the tribology of PM212 in air

NASA Technical Reports Server (NTRS)

Bogdanski, Michael S.; Sliney, Harold E.; Dellacorte, Christopher

1993-01-01

The effects of processing and compositional variations on the tribological performance of PM212 were studied. PM212 is a self lubricating powder metallurgy composite, comprised of a wear resistant metal bonded chromium carbide matrix, containing the solid lubricants barium fluoride/calcium fluoride eutectic and silver. Several composites were formulated which had lubricant, matrix, and processing variations. Processing variations included sintering and hot isostatic pressing. Pins fabricated from the composites were slid against superalloys disks in a pin-on-disk tribometer to study the tribological properties. Several composites exhibited low friction and wear in sliding against a nickel based superalloy. The tribological performance by several different composites showed that the composition of PM212 can be altered without dramatically affecting performance.

Rhenium-osmium isotope and highly-siderophile-element abundance systematics of angrite meteorites

NASA Astrophysics Data System (ADS)

Riches, Amy J. V.; Day, James M. D.; Walker, Richard J.; Simonetti, Antonio; Liu, Yang; Neal, Clive R.; Taylor, Lawrence A.

2012-11-01

Coupled 187Os/188Os compositions and highly-siderophile-element (HSE: Os, Ir, Ru, Pt, Pd, and Re) abundance data are reported for eight angrite achondrite meteorites that include quenched- and slowly-cooled textural types. These data are combined with new major- and trace-element concentrations determined for bulk-rock powder fractions and constituent mineral phases, to assess angrite petrogenesis. Angrite meteorites span a wide-range of HSE abundances from <0.005 ppb Os (e.g., Northwest Africa [NWA] 1296; Angra dos Reis) to >100 ppb Os (NWA 4931). Chondritic to supra-chondritic 187Os/188Os (0.1201-0.2127) measured for Angra dos Reis and quenched-angrites correspond to inter- and intra-sample heterogeneities in Re/Os and HSE abundances. Quenched-angrites have chondritic-relative rare-earth-element (REE) abundances at 10-15×CI-chondrite, and their Os-isotope and HSE abundance variations represent mixtures of pristine uncontaminated crustal materials that experienced addition (<0.8%) of exogenous chondritic materials during or after crystallization. Slowly-cooled angrites (NWA 4590 and NWA 4801) have fractionated REE-patterns, chondritic to sub-chondritic 187Os/188Os (0.1056-0.1195), as well as low-Re/Os (0.03-0.13), Pd/Os (0.071-0.946), and relatively low-Pt/Os (0.792-2.640). Sub-chondritic 187Os/188Os compositions in NWA 4590 and NWA 4801 are unusual amongst planetary basalts, and their HSE and REE characteristics may be linked to melting of mantle sources that witnessed prior basaltic melt depletion. Angrite HSE-Yb systematics suggest that the HSE behaved moderately-incompatibly during angrite magma crystallization, implying the presence of metal in the crystallizing assemblage. The new HSE abundance and 187Os/188Os compositions indicate that the silicate mantle of the angrite parent body(ies) (APB) had HSE abundances in chondritic-relative proportions but at variable abundances at the time of angrite crystallization. The HSE systematics of angrites are consistent with protracted post-core formation accretion of materials with chondritic-relative abundances of HSE to the APB, and these accreted materials were rapidly, yet inefficiently, mixed into angrite magma source regions early in Solar System history.

Melting mode and source lithology inferred from trace element systematic in historical olivine from Lanzarote, Canary Islands

NASA Astrophysics Data System (ADS)

Gómez-Ulla, Alejandra; Sigmarsson, Olgeir; Guðfinnsson, Guðmundur H.

2017-04-01

Trace element concentrations and ratios in olivine phenocrysts, such as fractionation-corrected Ni x (FeO/MgO) and Fe/Mn, have been shown useful as probes of pyroxenite derived component in mixtures of primary mantle melts (e.g. Sobolev et al., 2007). For instance, higher Ni and lower Mn and Ca contents are expected in partial melts of pyroxenite compared to those of lherzolite. We have measured trace element concentrations in olivine from 1730-1736 AD (Timanfaya) and 1824 AD eruptions in Lanzarote (Canary Islands), which erupted mafic and mantle nodule bearing magmas, ranging in composition from highly silica-undersaturated basanite through alkali basalt to tholeiite. The early basanite exhibit the largest olivine trace element variation covering the range of those from MORB and OIB worldwide, whereas later erupted tholeiite have values typical from pyroxenite derived melts. The Fo value decreased systematically with time during the 1730-36 eruption and the proportion of silica-saturated primary melt increased in the parental magma mixture with time. At the end of the eruption, tholeiite magmas crystallized olivine with, increasing concentrations of Mn and Ca and higher Ca/Al at relatively uniform Ni x (FeO/MgO) and Fe/Mn, all of which is readily explained by increased decompression melting at lower temperature. The basanite from the eruption that took place in 1824 AD has olivine with even higher Fo value and trace element variability similar those of the Timanfaya basanite. The fact that the Lanzarote basanite contain olivine with trace element systematic spanning that of MORB and pyroxenite melt can be explained by CO2-flux melting of a lithologically heterogeneous source, generating the diverse compositions. Initial reactive porous flow through depleted oceanic lithosphere and equilibration with dunitic restite of percolating pyroxenite melt may have amplified the observed Ni depletion in olivine of the earliest basanite. The fact that olivine compositions and basanite magma were reproduced approximately a century later may reflect episodic carbonatic fluxing in the slowly uprising Canarian mantle plume.

Stationary variational estimates for the effective response and field fluctuations in nonlinear composites

NASA Astrophysics Data System (ADS)

Ponte Castañeda, Pedro

2016-11-01

This paper presents a variational method for estimating the effective constitutive response of composite materials with nonlinear constitutive behavior. The method is based on a stationary variational principle for the macroscopic potential in terms of the corresponding potential of a linear comparison composite (LCC) whose properties are the trial fields in the variational principle. When used in combination with estimates for the LCC that are exact to second order in the heterogeneity contrast, the resulting estimates for the nonlinear composite are also guaranteed to be exact to second-order in the contrast. In addition, the new method allows full optimization with respect to the properties of the LCC, leading to estimates that are fully stationary and exhibit no duality gaps. As a result, the effective response and field statistics of the nonlinear composite can be estimated directly from the appropriately optimized linear comparison composite. By way of illustration, the method is applied to a porous, isotropic, power-law material, and the results are found to compare favorably with earlier bounds and estimates. However, the basic ideas of the method are expected to work for broad classes of composites materials, whose effective response can be given appropriate variational representations, including more general elasto-plastic and soft hyperelastic composites and polycrystals.

A 1.5 Ma record of plume-ridge interaction at the Western Galápagos Spreading Center (91°40‧-92°00‧W)

NASA Astrophysics Data System (ADS)

Herbrich, Antje; Hauff, Folkmar; Hoernle, Kaj; Werner, Reinhard; Garbe-Schönberg, Dieter; White, Scott

2016-07-01

Shallow (elevated) portions of mid-ocean ridges with enriched geochemical compositions near hotspots document the interaction of hot, geochemically-enriched plume mantle with shallow depleted upper mantle. Whereas the spatial variations in geochemical composition of ocean crust along the ridge axis in areas where plume-ridge interaction is taking place have been studied globally, only restricted information exists concerning temporal variations in geochemistry of ocean crust formed through plume-ridge interaction. Here we present a detailed geochemical study of 0-1.5 Ma ocean crust sampled from the Western Galápagos Spreading Center (WGSC) axis to 50 km north of the axis, an area that is presently experiencing a high influx of mantle material from the Galápagos hotspot. The tholeiitic to basaltic andesitic fresh glass and few bulk rock samples have incompatible element abundances and Sr-Nd-Pb isotopic compositions intermediate between depleted normal mid-ocean-ridge basalt (N-MORB) from >95.5°W along the WGSC and enriched lavas from the Galápagos Archipelago, displaying enriched (E-)MORB type compositions. Only limited and no systematic geochemical variations are observed with distance from the ridge axis for <1.0 Ma old WGSC crust, whereas 1.0-1.5 Ma old crust trends to more enriched isotopic compositions in 87Sr/86Sr, 143Nd/144Nd, 207Pb/204Pb and 208Pb/204Pb isotope ratios. On isotope correlation diagrams, the data set displays correlations between depleted MORB and two enriched components. Neither the geographically referenced geochemical domains of the Galápagos Archipelago nor the end members used for principal component analysis can successfully describe the observed mixing relations. Notably an off-axis volcanic cone at site DR63 has the appropriate composition to serve as the enriched component for the younger WGSC and could represent a portion of the northern part of the Galápagos plume not sampled south of the WGSC. Similar compositions to samples from volcanic cone DR63 have been found in the northern part of the 11-14 Ma Galápagos hotspot track offshore Costa Rica, indicating that this composition is derived from the northern portion of the Galápagos plume. The older WGSC requires involvement of an enriched mantle two (EMII) type source, not recognized thus far in the Galápagos system, and is interpreted to reflect entrained material either from small-scale heterogeneities within the upper mantle or from the mantle transition zone. Overall the source material for the 0-1.5 Ma WGSC ocean crust appears to represent mixing of depleted upper mantle with Northern Galápagos Plume material of relatively uniform composition in relatively constant proportions.

Limb Darkening and Planetary Transits: Testing Center-to-limb Intensity Variations and Limb-darkening Directly from Model Stellar Atmospheres

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

Neilson, Hilding R.; Lester, John B.; McNeil, Joseph T.

The transit method, employed by Microvariability and Oscillation of Stars ( MOST ), Kepler , and various ground-based surveys has enabled the characterization of extrasolar planets to unprecedented precision. These results are precise enough to begin to measure planet atmosphere composition, planetary oblateness, starspots, and other phenomena at the level of a few hundred parts per million. However, these results depend on our understanding of stellar limb darkening, that is, the intensity distribution across the stellar disk that is sequentially blocked as the planet transits. Typically, stellar limb darkening is assumed to be a simple parameterization with two coefficients thatmore » are derived from stellar atmosphere models or fit directly. In this work, we revisit this assumption and compute synthetic planetary-transit light curves directly from model stellar atmosphere center-to-limb intensity variations (CLIVs) using the plane-parallel Atlas and spherically symmetric SAtlas codes. We compare these light curves to those constructed using best-fit limb-darkening parameterizations. We find that adopting parametric stellar limb-darkening laws leads to systematic differences from the more geometrically realistic model stellar atmosphere CLIV of about 50–100 ppm at the transit center and up to 300 ppm at ingress/egress. While these errors are small, they are systematic, and they appear to limit the precision necessary to measure secondary effects. Our results may also have a significant impact on transit spectra.« less

Spatio-temporal variation of methane over Indian region: Seasonal and inter-annual variation .

NASA Astrophysics Data System (ADS)

M, K.; Nair, P. R.

2015-12-01

Methane (CH4) has an important role in the radiation budget and chemistry in the lower and middle atmosphere as a greenhouse and reactive trace gas. The rapid developments in the agriculture and industry over India have lead to the emission of many pollutants like CO, O3, CH4, CO2, SO2 etc into the atmosphere. However, their sources, sinks and concentration levels are poorly understood because of the lack of systematic sampling and monitoring. The advent of satellite remote sensing has helped to analyze the chemical composition of atmosphere with good spatial coverage especially over tropical region which was poorly sampled with the existing surface network. This work attempts an analysis of spatial distribution, seasonal cycle and inter annual variation of CH4 over Indian region during 2003-2009 using SCIAMACHY data onboard ENVISAT. Column CH4 varies from 1740-1890 ppbv over Indian region with distinct spatial and temporal features. We observed a dependence of seasonal CH4 variation on rice cultivation, convective activities and changes in boundary layer characteristics. The comparative study using satellite, aircraft and surface measurement shown CH4 has non-homogeneity in its distribution and seasonal variation in different layers of atmosphere. A comparative study of CH4 at different hot spot regions over the globe was carried out which showed prominent hemispherical variations. Large spread in column CH4 was observed at India and Chinese region compared to other regions with a significant seasonal variability. This study points to the blending of satellite, aircraft and surface measurements for the realization of regional distribution of CH4.

Intra-plant Variation in Nectar Sugar Composition in Two Aquilegia Species (Ranunculaceae): Contrasting Patterns under Field and Glasshouse Conditions

PubMed Central

Canto, Azucena; Pérez, Ricardo; Medrano, Mónica; Castellanos, María Clara; Herrera, Carlos M.

2007-01-01

Background and Aims Intra-specific variation in nectar chemistry under natural conditions has been only rarely explored, yet it is an essential aspect of our understanding of how pollinator-mediated selection might act on nectar traits. This paper examines intra-specific variation in nectar sugar composition in field and glasshouse plants of the bumblebee-pollinated perennial herbs Aquilegia vulgaris subsp. vulgaris and Aquilegia pyrenaica subsp. cazorlensis (Ranunculaceae). The aims of the study are to assess the generality of extreme intra-plant variation in nectar sugar composition recently reported for other species in the field, and gaining insight on the possible mechanisms involved. Methods The proportions of glucose, fructose and sucrose in single-nectary nectar samples collected from field and glasshouse plants were determined using high performance liquid chromatography. A hierarchical variance partition was used to dissect total variance into components due to variation among plants, flowers within plants, and nectaries within flowers. Key Results Nectar of the two species was mostly sucrose-dominated, but composition varied widely in the field, ranging from sucrose-only to fructose-dominated. Most intra-specific variance was due to differences among nectaries of the same flower, and flowers of the same plant. The high intra-plant variation in sugar composition exhibited by field plants vanished in the glasshouse, where nectar composition emerged as a remarkably constant feature across plants, flowers and nectaries. Conclusions In addition to corroborating the results of previous studies documenting extreme intra-plant variation in nectar sugar composition in the field, this study suggests that such variation may ultimately be caused by biotic factors operating on the nectar in the field but not in the glasshouse. Pollinator visitation and pollinator-borne yeasts are suggested as likely causal agents. PMID:17259227

Variations in the abundance of iron on Mercury's surface from MESSENGER X-Ray Spectrometer observations

NASA Astrophysics Data System (ADS)

Weider, Shoshana Z.; Nittler, Larry R.; Starr, Richard D.; McCoy, Timothy J.; Solomon, Sean C.

2014-06-01

We present measurements of Mercury's surface composition from the analysis of MESSENGER X-Ray Spectrometer data acquired during 55 large solar flares, which each provide a statistically significant detection of Fe X-ray fluorescence. The Fe/Si data display a clear dependence on phase angle, for which the results are empirically corrected. Mercury's surface has a low total abundance of Fe, with a mean Fe/Si ratio of ˜0.06 (equivalent to ˜1.5 wt% Fe). The absolute Fe/Si values are subject to a number of systematic uncertainties, including the phase-angle correction and possible mineral mixing effects. Individual Fe/Si measurements have an intrinsic error of ˜10%. Observed Fe/Si values display small variations (significant at two standard deviations) from the planetary average value across large regions in Mercury's southern hemisphere. Larger differences are observed between measured Fe/Si values from more spatially resolved footprints on volcanic smooth plains deposits in the northern hemisphere and from those in surrounding terrains. Fe is most likely contained as a minor component in sulfide phases (e.g., troilite, niningerite, daubréelite) and as Fe metal, rather than within mafic silicates. Variations in surface reflectance (i.e., differences in overall reflectance and spectral slope) across Mercury are unlikely to be caused by variations in the abundance of Fe.

Toward DNA-based facial composites: preliminary results and validation.

PubMed

Claes, Peter; Hill, Harold; Shriver, Mark D

2014-11-01

The potential of constructing useful DNA-based facial composites is forensically of great interest. Given the significant identity information coded in the human face these predictions could help investigations out of an impasse. Although, there is substantial evidence that much of the total variation in facial features is genetically mediated, the discovery of which genes and gene variants underlie normal facial variation has been hampered primarily by the multipartite nature of facial variation. Traditionally, such physical complexity is simplified by simple scalar measurements defined a priori, such as nose or mouth width or alternatively using dimensionality reduction techniques such as principal component analysis where each principal coordinate is then treated as a scalar trait. However, as shown in previous and related work, a more impartial and systematic approach to modeling facial morphology is available and can facilitate both the gene discovery steps, as we recently showed, and DNA-based facial composite construction, as we show here. We first use genomic ancestry and sex to create a base-face, which is simply an average sex and ancestry matched face. Subsequently, the effects of 24 individual SNPs that have been shown to have significant effects on facial variation are overlaid on the base-face forming the predicted-face in a process akin to a photomontage or image blending. We next evaluate the accuracy of predicted faces using cross-validation. Physical accuracy of the facial predictions either locally in particular parts of the face or in terms of overall similarity is mainly determined by sex and genomic ancestry. The SNP-effects maintain the physical accuracy while significantly increasing the distinctiveness of the facial predictions, which would be expected to reduce false positives in perceptual identification tasks. To the best of our knowledge this is the first effort at generating facial composites from DNA and the results are preliminary but certainly promising, especially considering the limited amount of genetic information about the face contained in these 24 SNPs. This approach can incorporate additional SNPs as these are discovered and their effects documented. In this context we discuss three main avenues of research: expanding our knowledge of the genetic architecture of facial morphology, improving the predictive modeling of facial morphology by exploring and incorporating alternative prediction models, and increasing the value of the results through the weighted encoding of physical measurements in terms of human perception of faces. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Isotope chemistry of an extensively nitrate-contaminated urban aquifer

NASA Astrophysics Data System (ADS)

Kracht, O.; de Souza, L. C.; de Queiros, M. A.; Stegemann, C.; Hunziker, J.

2003-04-01

The supply of drinking water for the approximately 800.000 inhabitants of the city of Natal (Rio Grande do Norte, Brazil) is strongly dependent on the use of local groundwater from the Barreiras Aquifer. Over 70 % of the public production are served by a system of about 130 tubular wells, that are distributed all over the urban area. Yet, no groundwater protection zones have been declared. In addition, a comparable number of private wells also depend on the cities underground water resources. Depending on the local topography, the groundwater table is located several tens of meters below surface. Useable groundwater occurrences are bound to an up to hundred meters thick series of unconsolidated clastic sediments from the younger tertiary (Barreiras Formation), that is underlain by less permeable cretaceous carbonates. Natals topography is dominated by impressive quaternary dunes formations, that play an important role for the infiltration of rain as the only source of recharge for the local groundwater. During the last decades, an extensive and rapidly growing groundwater-contamination with up to over 100 mg/l nitrate was observed by the local authorities. Hydrochemical data indicate this deterioration to be due to a massive spill of sanitary effluents over septic pits, as only 20 % of the city is yet served by a sewer system. The isotopic composition of Natals groundwater shows only small variations, with an average δ18O value of -2,3 per mill and δ2H value of -10,5 per mill vs. SMOW. Its origin from recent local precipitation is revealed by a good correspondence with the annual weighted means for precipitation in Ceara Mirim (nearest GNIP station, situated 45 km NE of Natal). In contrast, a set of samples from different regional surface waters indicated a strong evaporation trend with systematic enrichment in the oxygen and hydrogen isotopic composition. Samples from 33 production wells with a wide variation of nitrate concentrations were investigated for their isotopic composition of nitrate. The average δ15N value of +9,3 per mill vs. AIR and δ18O value of +10,8 per mill vs. SMOW consist with the assumption of sewage being the primary source of contamination. Observed variations in the oxygen isotope values are in the range of analytical precision, whereas the nitrogen isotope values vary stronger. This effect is assumed to be due to a varying degree of ammonia volatilisation before nitrification in the unsaturated zone. On the contrary, there is no hint for an ongoing bacterial reduction of nitrate, that should have been expressed by a systematic enrichment in both its oxygen and nitrogen isotope values. Degradation of nitrate seems to be inhibited due to the absence of a suitable electron donator and comparable high oxygenated conditions in the aquifer.

Efficacy of a Systematic Prompt Reduction Strategy in Teaching Independent Composition. [Final Report.

ERIC Educational Resources Information Center

Harriman, Nancy; Schloss, Patrick J.

The use of systematic prompting and monitoring to increase written sentence production during a ten-minute assigned composition task was investigated with 78 learning disabled (LD) students in grades 7-12. Subjects were classified as LD, were receiving special education services, and evidenced at least a 2-year lag in written language skills. Six…

Environmental characteristics drive variation in Amazonian understorey bird assemblages

PubMed Central

Magnusson, William E.; Anderson, Marti J.; Schlegel, Martin; Pe’er, Guy; Henle, Klaus

2017-01-01

Tropical bird assemblages display patterns of high alpha and beta diversity and, as tropical birds exhibit strong habitat specificity, their spatial distributions are generally assumed to be driven primarily by environmental heterogeneity and interspecific interactions. However, spatial distributions of some Amazonian forest birds are also often restricted by large rivers and other large-scale topographic features, suggesting that dispersal limitation may also play a role in driving species’ turnover. In this study, we evaluated the effects of environmental characteristics, topographic and spatial variables on variation in local assemblage structure and diversity of birds in an old-growth forest in central Amazonia. Birds were mist-netted in 72 plots distributed systematically across a 10,000 ha reserve in each of three years. Alpha diversity remained stable through time, but species composition changed. Spatial variation in bird-assemblage structure was significantly related to environmental and topographic variables but not strongly related to spatial variables. At a broad scale, we found bird assemblages to be significantly distinct between two watersheds that are divided by a central ridgeline. We did not detect an effect of the ridgeline per se in driving these patterns, indicating that most birds are able to fly across it, and that differences in assemblage structure between watersheds may be due to unmeasured environmental variables or unique combinations of measured variables. Our study indicates that complex geography and landscape features can act together with environmental variables to drive changes in the diversity and composition of tropical bird assemblages at local scales, but highlights that we still know very little about what makes different parts of tropical forest suitable for different species. PMID:28225774

There’s More to Groove than Bass in Electronic Dance Music: Why Some People Won’t Dance to Techno

PubMed Central

2016-01-01

The purpose of this study was to explore the relationship between audio descriptors for groove-based electronic dance music (EDM) and raters’ perceived cognitive, affective, and psychomotor responses. From 198 musical excerpts (length: 15 sec.) representing 11 subgenres of EDM, 19 low-level audio feature descriptors were extracted. A principal component analysis of the feature vectors indicated that the musical excerpts could effectively be classified using five complex measures, describing the rhythmical properties of: (a) the high-frequency band, (b) the mid-frequency band, and (c) the low-frequency band, as well as overall fluctuations in (d) dynamics, and (e) timbres. Using these five complex audio measures, four meaningful clusters of the EDM excerpts emerged with distinct musical attributes comprising music with: (a) isochronous bass and static timbres, (b) isochronous bass with fluctuating dynamics and rhythmical variations in the mid-frequency range, (c) non-isochronous bass and fluctuating timbres, and (d) non-isochronous bass with rhythmical variations in the high frequencies. Raters (N = 99) were each asked to respond to four musical excerpts using a four point Likert-Type scale consisting of items representing cognitive (n = 9), affective (n = 9), and psychomotor (n = 3) domains. Musical excerpts falling under the cluster of “non-isochronous bass with rhythmical variations in the high frequencies” demonstrated the overall highest composite scores as evaluated by the raters. Musical samples falling under the cluster of “isochronous bass with static timbres” demonstrated the overall lowest composite scores as evaluated by the raters. Moreover, music preference was shown to significantly affect the systematic patterning of raters’ responses for those with a musical preference for “contemporary” music, “sophisticated” music, and “intense” music. PMID:27798645

There's More to Groove than Bass in Electronic Dance Music: Why Some People Won't Dance to Techno.

PubMed

Wesolowski, Brian C; Hofmann, Alex

2016-01-01

The purpose of this study was to explore the relationship between audio descriptors for groove-based electronic dance music (EDM) and raters' perceived cognitive, affective, and psychomotor responses. From 198 musical excerpts (length: 15 sec.) representing 11 subgenres of EDM, 19 low-level audio feature descriptors were extracted. A principal component analysis of the feature vectors indicated that the musical excerpts could effectively be classified using five complex measures, describing the rhythmical properties of: (a) the high-frequency band, (b) the mid-frequency band, and (c) the low-frequency band, as well as overall fluctuations in (d) dynamics, and (e) timbres. Using these five complex audio measures, four meaningful clusters of the EDM excerpts emerged with distinct musical attributes comprising music with: (a) isochronous bass and static timbres, (b) isochronous bass with fluctuating dynamics and rhythmical variations in the mid-frequency range, (c) non-isochronous bass and fluctuating timbres, and (d) non-isochronous bass with rhythmical variations in the high frequencies. Raters (N = 99) were each asked to respond to four musical excerpts using a four point Likert-Type scale consisting of items representing cognitive (n = 9), affective (n = 9), and psychomotor (n = 3) domains. Musical excerpts falling under the cluster of "non-isochronous bass with rhythmical variations in the high frequencies" demonstrated the overall highest composite scores as evaluated by the raters. Musical samples falling under the cluster of "isochronous bass with static timbres" demonstrated the overall lowest composite scores as evaluated by the raters. Moreover, music preference was shown to significantly affect the systematic patterning of raters' responses for those with a musical preference for "contemporary" music, "sophisticated" music, and "intense" music.

Influence of defects on the charge density wave of ([SnSe] 1+δ) 1(VSe 2) 1 ferecrystals

DOE PAGES

Falmbigl, Matthias; Putzky, Daniel; Ditto, Jeffrey; ...

2015-07-14

A series of ferecrystalline compounds ([SnSe] 1+δ) 1(VSe 2) 1 with varying Sn/V ratios were synthesized using the modulated elemental reactant technique. Temperature-dependent specific heat data reveal a phase transition at 102 K, where the heat capacity changes abruptly. An abrupt increase in electrical resistivity occurs at the same temperature, correlated with an abrupt increase in the Hall coefficient. Combined with the magnitude and nature of the specific heat discontinuity, this suggests that the transition is similar to the charge density wave transitions in transition metal dichalcogenides. An ordered intergrowth was formed over a surprisingly wide compositional range of Sn/Vmore » ratios of 0.89 ≤ 1 + δ ≤ 1.37. X-ray diffraction and transmission electron microscopy reveal the formation of various volume defects in the compounds in response to the nonstoichiometry. The electrical resistivity and Hall coefficient data of samples with different Sn/V ratios show systematic variation in the carrier concentration with the Sn/V ratio. There is no significant change in the onset temperature of the charge density wave transition, only a variation in the carrier densities before and after the transition. Given the sensitivity of the charge density wave transitions of transition metal dichalcogenides to variations in composition, it is very surprising that the charge density wave transition observed at 102 K for ([SnSe] 1.15) 1(VSe 2) 1 is barely influenced by the nonstoichiometry and structural defects. As a result, this might be a consequence of the two-dimensional nature of the structurally independent VSe 2 layers.« less

OIB signatures in basin-related lithosphere-derived alkaline basalts from the Batain basin (Oman) - Constraints from 40Ar/39Ar ages and Nd-Sr-Pb-Hf isotopes

NASA Astrophysics Data System (ADS)

Witte, M.; Jung, S.; Pfänder, J. A.; Romer, R. L.; Mayer, B.; Garbe-Schönberg, D.

2017-08-01

Tertiary rift-related intraplate basanites from the Batain basin of northeastern Oman have low SiO2 (< 45.6 wt.%), high MgO (> 9.73 wt.%) and moderate to high Cr and Ni contents (Cr > 261 ppm, Ni > 181 ppm), representing near primary magmas that have undergone fractionation of mainly olivine and magnetite. Rare earth element systematics and p-T estimates suggest that the alkaline rocks are generated by different degrees of partial melting (4-13%) of a spinel-peridotite lithospheric mantle containing residual amphibole. The alkaline rocks show restricted variations of 87Sr/86Sr and 143Nd/144Nd ranging from 0.70340 to 0.70405 and 0.51275 to 0.51284, respectively. Variations in Pb isotopes (206Pb/204Pb: 18.59-18.82, 207Pb/204Pb: 15.54-15.56, 208Pb/204Pb: 38.65-38.98) of the alkaline rocks fall in the range of most OIB. Trace element constraints together with Sr-Nd-Pb isotope composition indicate that assimilation through crustal material did not affect the lavas. Instead, trace element variations can be explained by melting of a lithospheric mantle source that was metasomatized by an OIB-type magma that was accumulated at the base of the lithosphere sometimes in the past. Although only an area of less than 1000 km2 was sampled, magmatic activity lasted for about 5.5 Ma with a virtually continuous activity from 40.7 ± 0.7 to 35.3 ± 0.6 Ma. During this period magma composition was nearly constant, i.e. the degree of melting and the nature of the tapped source did not change significantly over time.

Study of magnetism in Ni-Cr hardface alloy deposit on 316LN stainless steel using magnetic force microscopy

NASA Astrophysics Data System (ADS)

Kishore, G. V. K.; Kumar, Anish; Chakraborty, Gopa; Albert, S. K.; Rao, B. Purna Chandra; Bhaduri, A. K.; Jayakumar, T.

2015-07-01

Nickel base Ni-Cr alloy variants are extensively used for hardfacing of austenitic stainless steel components in sodium cooled fast reactors (SFRs) to avoid self-welding and galling. Considerable difference in the compositions and melting points of the substrate and the Ni-Cr alloy results in significant dilution of the hardface deposit from the substrate. Even though, both the deposit and the substrate are non-magnetic, the diluted region exhibits ferromagnetic behavior. The present paper reports a systematic study carried out on the variations in microstructures and magnetic behavior of American Welding Society (AWS) Ni Cr-C deposited layers on 316 LN austenitic stainless steels, using atomic force microscopy (AFM) and magnetic force microscopy (MFM). The phase variations of the oscillations of a Co-Cr alloy coated magnetic field sensitive cantilever is used to quantitatively study the magnetic strength of the evolved microstructure in the diluted region as a function of the distance from the deposit/substrate interface, with the spatial resolution of about 100 nm. The acquired AFM/MFM images and the magnetic property profiles have been correlated with the variations in the chemical compositions in the diluted layers obtained by the energy dispersive spectroscopy (EDS). The study indicates that both the volume fraction of the ferromagnetic phase and its ferromagnetic strength decrease with increasing distance from the deposit/substrate interface. A distinct difference is observed in the ferromagnetic strength in the first few layers and the ferromagnetism is observed only near to the precipitates in the fifth layer. The study provides a better insight of the evolution of ferromagnetism in the diluted layers of Ni-Cr alloy deposits on stainless steel.

Origins of cryptic variation in the Ediacaran-Fortunian rhyolitic ignimbrites of the Saldanha Bay Volcanic Complex, Western Cape, South Africa

NASA Astrophysics Data System (ADS)

Clemens, J. D.; Stevens, G.; Frei, D.; Joseph, C. S. A.

2017-12-01

The Saldanha eruption centre, on the West Coast of South Africa, consists of 542 Ma, intracaldera, S-type, rhyolite ignimbrites divided into the basal Saldanha Ignimbrite and the partly overlying Jacob's Bay Ignimbrite. Depleted-mantle Nd model ages suggest magma sources younger than the Early Mesoproterozoic, and located within the Neoproterozoic Malmesbury Group and Swartland complex metasedimentary and metavolcanic rocks that form the regional basement. The Sr isotope systematics suggest that the dominant source rocks were metavolcaniclastic rocks and metagreywackes, and that the magmas formed from separate batches extracted from the same heterogeneous source. No apparent magma mixing trends relate the Saldanha to the Jacob's Bay Ignimbrites, or either of these to the magmas that formed the Plankiesbaai or Tsaarsbank Ignimbrites in the neighbouring Postberg eruption centre. The magmas were extracted from their source rocks carrying small but significant proportions of peritectic and restitic accessory minerals. Variations in the content of this entrained crystal cargo were responsible for most of the chemical variations in the magmas. Although we cannot construct a cogent crystal fractionation model to relate these groups of magmas, at least some crystal fractionation occurred, as an overlay on the primary signal due to peritectic assemblage entrainment (PAE). Thus, the causes of the cryptic chemical variation among the ignimbrite magmas of the Saldanha centre are variable, but dominated by the compositions of the parent melts and PAE. The preservation of clear, source-inherited chemical signatures, in individual samples, calls into question the common interpretation of silicic calderas as having been formed in large magma reservoirs, with magma compositions shaped by magma mingling, mixing, and fractional crystallization. The Saldanha rocks suggest a more intimate connection between source and erupted magma, and perhaps indicate that silicic magmas are too viscous to be significantly modified by magma-chamber processes.

High resolution HH-XRF scanning and XRD modelling as a tool in sedimentological analysis - A case study from the Enreca-3 core, Bach Long Vi Island, Vietnam

NASA Astrophysics Data System (ADS)

Rizzi, Malgorzata; Hemmingsen Schovsbo, Niels; Korte, Christoph; Bryld Wessel Fyhn, Michael

2017-04-01

To improve the understanding and interpretation of the depositional environment of a late Oligocene lacustrine organic rich oil-prone source rock succession, 2464 hand held (HH)-XRF measurements were made systematically on the 500 m long, continuous core from the fully cored Enreca-3 well. This core, drilled on the remote Bach Long Vi Island, northern Gulf of Tonkin, offshore Vietnam, represents a deep lake succession alternating between lacustrine pelagic dominated sediments interrupted by hyperpycnal turbidites, high density turbidites and debris flows [1, 2]. From a combined HH-XRF-XRD data set, multivariate data analysis and regression models are used to type the rock and to predict the XRD mineral composition based on HH-XRF composition. The rock types and the modelled mineral composition highlight the geochemical variations of the sediment and allows for direct comparison with sedimentological processes and facies changes. The modeling also depicts the cyclic alteration of rock types that are present on many different scales ranging from centimeters to hundreds of meters [1, 2]. The sedimentological and geochemical variations observed throughout the cored section reflects fluctuating paleoclimate, tectonism and hinterland condition controlling the depositional setting, which may provide a deeper understanding of the deposition of this and similar Paleogene syn-rift succession in the South China Sea region. It allows furthermore the development of a more generalized depositional model relevant for other deep-lacustrine syn-rift basins. [1] Petersen et al. (2014) Journal of Petroleum Geology, 37: 373-389. [2] Hovikoski et al. (2016) Journal of Sedimentary Research, 86(8): 982-1007.

Implications of L1 Observations for Slow Solar Wind Formation by Solar Reconnection

NASA Technical Reports Server (NTRS)

Kepko, L.; Viall, N. M.; Antiochos, S. K.; Lepri, S. T.; Kasper, J. C.; Weberg, M.

2016-01-01

While the source of the fast solar wind is known to be coronal holes, the source of the slow solar wind has remained a mystery. Long time scale trends in the composition and charge states show strong correlations between solar wind velocity and plasma parameters, yet these correlations have proved ineffective in determining the slow wind source. We take advantage of new high time resolution (12 min) measurements of solar wind composition and charge state abundances at L1 and previously identified 90 min quasi periodic structures to probe the fundamental timescales of slow wind variability. The combination of new high temporal resolution composition measurements and the clearly identified boundaries of the periodic structures allows us to utilize these distinct solar wind parcels as tracers of slowwind origin and acceleration. We find that each 90 min (2000 Mm) parcel of slow wind has near-constant speed yet exhibits repeatable, systematic charge state and composition variations that span the entire range of statistically determined slow solar wind values. The classic composition-velocity correlations do not hold on short, approximately hour long, time scales. Furthermore, the data demonstrate that these structures were created by magnetic reconnection. Our results impose severe new constraints on slow solar wind origin and provide new, compelling evidence that the slow wind results from the sporadic release of closed field plasma via magnetic reconnection at the boundary between open and closed flux in the Sun's atmosphere.

How well do satellite observations and models capture diurnal variation in aerosols over the Korean Peninsula?

NASA Astrophysics Data System (ADS)

Hyer, E. J.; Xian, P.; Campbell, J. R.

2016-12-01

Aerosol sources, sinks, and transport processes have important variations over the diurnal cycle. Advances in geostationary satellite observation have made it possible to retrieve aerosol properties over a larger fraction of the diurnal cycle in many areas. However, the conditions for retrieval of aerosol from space also have systematic diurnal variation, which must be considered when interpreting satellite data. We used surface PM2.5 observations from the Korean National Institute for Environmental Research, together with the dense network of AERONET sun photometers deployed in Korea for the KORUS-AQ mission in spring 2016, to examine diurnal variations in aerosol conditions and quantify the effect of systematic diurnal processes on daily integrated aerosol quantities of forcing and PM2.5 24-hour exposure. Time-resolved observations of aerosols from in situ data were compared to polar and geostationary satellite observations to evaluate these questions: 1) How well is diurnal variation observed in situ captured by satellite products? 2) Do the satellite products show evidence of systematic biases related to diurnally varying observing conditions? 3) What is the implication of diurnal variation for aerosol forcing estimates based on observations near solar noon? The diurnal variation diagnosed from observations was also compared to the output of the Navy Aerosol Analysis and Prediction System (NAAPS), to examine the ability of this model to capture aerosol diurnal variation. Finally, we discuss the implications of the observed diurnal variation for assimilation of aerosol observations into forecast models.

Analysis of copy number variations among cattle breeds

USDA-ARS?s Scientific Manuscript database

Genomic structural variation is an important and abundant source of genetic and phenotypic variation. Here we describe the first systematic and genome-wide analysis of copy number variations (CNVs) in the modern domesticated cattle using array comparative genomic hybridization (array CGH) and quanti...

High intralocus variability and interlocus recombination promote immunological diversity in a minimal major histocompatibility system.

PubMed

Wilson, Anthony B; Whittington, Camilla M; Bahr, Angela

2014-12-20

The genes of the major histocompatibility complex (MHC/MH) have attracted considerable scientific interest due to their exceptional levels of variability and important function as part of the adaptive immune system. Despite a large number of studies on MH class II diversity of both model and non-model organisms, most research has focused on patterns of genetic variability at individual loci, failing to capture the functional diversity of the biologically active dimeric molecule. Here, we take a systematic approach to the study of MH variation, analyzing patterns of genetic variation at MH class IIα and IIβ loci of the seahorse, which together form the immunologically active peptide binding cleft of the MH class II molecule. The seahorse carries a minimal class II system, consisting of single copies of both MH class IIα and IIβ, which are physically linked and inherited in a Mendelian fashion. Both genes are ubiquitously expressed and detectible in the brood pouch of male seahorses throughout pregnancy. Genetic variability of the two genes is high, dominated by non-synonymous variation concentrated in their peptide-binding regions. Coding variation outside these regions is negligible, a pattern thought to be driven by intra- and interlocus recombination. Despite the tight physical linkage of MH IIα and IIβ loci, recombination has produced novel composite alleles, increasing functional diversity at sites responsible for antigen recognition. Antigen recognition by the adaptive immune system of the seahorse is enhanced by high variability at both MH class IIα and IIβ loci. Strong positive selection on sites involved in pathogen recognition, coupled with high levels of intra- and interlocus recombination, produce a patchwork pattern of genetic variation driven by genetic hitchhiking. Studies focusing on variation at individual MH loci may unintentionally overlook an important component of ecologically relevant variation.

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

Ju, James; Loitsch, Bernhard; Stettner, Thomas

We elucidate the role of growth parameters (III/N flux ratio, temperature T{sub G}) on the morphological and structural properties, as well as compositional homogeneity and carrier localization effects of high In-content (x(In) > 0.75) In–polar InGaN films grown by plasma–assisted molecular beam epitaxy (PAMBE). Variations in III/N flux ratio evidence that higher excess of In yields higher threading dislocation densities as well as larger compositional inhomogeneity as measured by x-ray diffraction. Most interestingly, by variation of growth temperature T{sub G} we find a significant trade-off between improved morphological quality and compositional homogeneity at low–T{sub G} (∼450–550 °C) versus improved threading dislocation densities atmore » high–T{sub G} (∼600–630 °C), as exemplified for InGaN films with x(In) = 0.9. The enhanced compositional homogeneity mediated by low–T{sub G} growth is confirmed by systematic temperature-dependent photoluminescence (PL) spectroscopy data, such as lower PL peakwidths, >5× higher PL efficiency (less temperature-induced quenching) and a distinctly different temperature-dependent S-shape behavior of the PL peak energy. From these, we find that the carrier localization energy is as low as ∼20 meV for low–T{sub G} grown films (T{sub G} = 550 °C), while it rises to ∼70 meV for high–T{sub G} grown films (T{sub G} = 630 °C) right below the onset of In–N dissociation. These findings point out that for the kinetically limited metal-rich PAMBE growth of high In-content InGaN a III/N flux ratio of ∼1 and low-to-intermediate T{sub G} are required to realize optically more efficient materials.« less

Re-Os Isotopic Constraints on the Chemical Evolution and Differentiation of the Martian Mantle

NASA Technical Reports Server (NTRS)

Brandon, Alan D.; Walker, Richard J.

2002-01-01

The (187)Re-187Os isotopic systematics of SNC meteorites, thought to be from Mars, provide valuable information regarding the chemical processes that affected the Martian mantle, particularly with regard to the relative abundances of highly siderophile elements (HSE). Previously published data (Birck and Allegre 1994, Brandon et al. 2000), and new data obtained since these studies, indicate that the HSE and Os isotopic composition of the Martian mantle was primarily set in its earliest differentiation history. If so, then these meteorites provide key constraints on the processes that lead to variation in HSE observed in not only Mars, but also Earth, the Moon and other rocky bodies in the Solar System. Processes that likely have an effect on the HSE budgets of terrestrial mantles include core formation, magma ocean crystallization, development of juvenile crust, and the addition of a late veneer. Each of these processes will result in different HSE variation and the isotopic composition of mantle materials and mantle derived lavas. Two observations on the SNC data to present provide a framework for which to test the importance of each of these processes. First, the concentrations of Re and Os in SNC meteorites indicate that they are derived from a mantle that has similar concentrations to the Earth's mantle. Such an observation is consistent with a model where a chondritic late veneer replenished the Earth and Martian mantles subsequent to core formation on each planet. Alternative models to explain this observation do exist, but will require additional data to test the limitations of each. Second, Re-Os isotopic results from Brandon et al. (2000) and new data presented here, show that initial yos correlates with variations in the short-lived systems of (182)Hf- (182)W and (142)Sm-142Nd in the SNC meteorites (epsilon(sub W) and epsilon(sub 142Nd)). These systematics require an isolation of mantle reservoirs during the earliest differentiation history of Mars, and subsequent inefficient mixing between these reservoirs. These data show that models for the origin of isotopic variation for SNC meteorites require at least two long-lived mantle reservoirs, and possibly three. The range in the projected present day gamma(sub Os) of these reservoirs is from -5.4+/-2.6, to +4+/-1. The isotopic systematics of these reservoirs may be linked to development of cumulate crystal piles in a Martian magma ocean and variable amounts of late stage intercumulus melt. In this model, fractional crystallization of olivine and possibly other phases with slightly subchondritic Re/Os, from a solidifying magma ocean, resulted in a lower Re/Os ratio early cumulates, and a resultant low gamma(sub Os). Later cumulates or evolved melts crystallized with higher Re/Os ratios to produce the mantle reservoir(s) with consequent higher gamma(sub Os). Crystallization of the Martian magma ocean followed earliest core formation, as indicated by the correlation of epsilon(sub W) with epsilon(sub 142Nd) and initial gamma(sub Os).

How do cuticular hydrocarbons evolve? Physiological constraints and climatic and biotic selection pressures act on a complex functional trait

PubMed Central

Blaimer, Bonnie B.; Schmitt, Thomas

2017-01-01

Cuticular hydrocarbons (CHCs) cover the cuticles of virtually all insects, serving as a waterproofing agent and as a communication signal. The causes for the high CHC variation between species, and the factors influencing CHC profiles, are scarcely understood. Here, we compare CHC profiles of ant species from seven biogeographic regions, searching for physiological constraints and for climatic and biotic selection pressures. Molecule length constrained CHC composition: long-chain profiles contained fewer linear alkanes, but more hydrocarbons with disruptive features in the molecule. This is probably owing to selection on the physiology to build a semi-fluid cuticular layer, which is necessary for waterproofing and communication. CHC composition also depended on the precipitation in the ants' habitats. Species from wet climates had more alkenes and fewer dimethyl alkanes than those from drier habitats, which can be explained by different waterproofing capacities of these compounds. By contrast, temperature did not affect CHC composition. Mutualistically associated (parabiotic) species possessed profiles highly distinct from non-associated species. Our study is, to our knowledge, the first to show systematic impacts of physiological, climatic and biotic factors on quantitative CHC composition across a global, multi-species dataset. We demonstrate how they jointly shape CHC profiles, and advance our understanding of the evolution of this complex functional trait in insects. PMID:28298343

The Divnoe meteorite: Petrology, chemistry, oxygen isotopes and origin

NASA Technical Reports Server (NTRS)

Petaev, M. I.; Barsukova, L. D.; Lipschultz, M. E.; Wang, M.-S.; Ariskin, A. A.; Clayton, R. N.; Mayeda, T. K.

1994-01-01

The Divnoe meteorite is an olivine-rich primitive achondrite with subchondritic chemistry and mineralogy. It has a granoblastic, coarse-grained, olivine groundmass (CGL: coarse-grained lithology) with relatively large pyroxene-plagioclase poiklitic patches (PP) and small fine-grained domains of an opaque-rich lithology (ORL). Both PP and ORL are inhomogeneously distributed and display reaction boundaries with the groundmass. Major silicates, olivine Fa(20-28) and orthopyroxyene Fs(20-28 Wo(0.5-2.5), display systematic differences in composition between CGL and ORL as well as a complicated pattern of variations within CGL. Accessory plagioclase has low K content and displays regular igneous zoning with core compositions An(40-45) and rims An(32-37). The bulk chemical composition of Divnoe is similar to that of olivine-rich primitive achondrites, except for a depletion of incompatible elements and minor enrichment of refractory siderophiles. Oxygen isotope compositions for whole-rock and separated minerals from Divnoe fall in a narrow range, with mean delta O-18 = +4.91, delta O-17 = +2.24, and Delta O-17 = -0.26 +/- 0.11. The isotopic composition is not within the range of any previously recognized group but is very close to that of the brachinites. To understand the origin of Divnoe lithologies, partial melting and crystallization were modelled using starting compositions equal to that of Divnoe and some chondritic meteorites. It was found that the Divnoe composition could be derived from a chondritic source region by approximately 20 wt% partial melting at Ta approximately 1300 C and log(fO2) = IW-1.8, followed by approximtely 60 wt% crystallization of the partial melt formed, and removal of the still-liquid portion of the partial melt. Removal of the last partial melt resulted in depletion of the Divnoe plagioclase in Na and K. In this scenario, CGL represents the residue of partial melting, and PP is a portion of the partial melt that crystallized in situ. The ORL was formed during the final stages of partial melting by reaction between gaseous sulfur and residual olivine in the source region. A prominent feature of Divnoe is fine micron-scale chemical variations within olivine grains, related to lamellar structures the olivines display. The origin of these structures is not known.

Do Nanofilled/Nanohybrid Composites Allow for Better Clinical Performance of Direct Restorations Than Traditional Microhybrid Composites? A Systematic Review.

PubMed

Angerame, D; De Biasi, M

2018-03-23

This systematic review was carried out to assess the clinical effectiveness of nanofilled and nanohybrid composites used for direct restorations in comparison with microhybrid composites. The guidelines for the preferred reporting items for systematic reviews and meta-analyses were followed. A search of articles published from July 1996 to February 2017 was performed in PubMed, SciVerse Scopus, Latin American and Caribbean Health Sciences, the Scientific Electronic Library Online, and the Cochrane Library. The present review selected only randomized controlled trials comparing the clinical performance of a nanofilled or nanohybrid composite for direct restorations with that of a microhybrid composite. The research found 201 studies. Twenty-one articles fulfilled the criteria of the present review. However, the included studies were characterized by great methodological diversities. As a general trend, nanofilled and nanohybrid composites were found to be capable of clinical performance, marginal quality, and resistance to wear similar to that of traditional composites without showing improved surface characteristics. The risk of bias of included studies was judged unclear or high. The clinical performance of nanofilled/nanohybrid composites was found to be comparable to that of traditional composites in the posterior area. The data concerning anterior and cervical restorations were insufficient. With regard to the esthetic properties, there is a compelling need for studies on anterior teeth in which the operators are kept unaware of the restorative material. Nanofilled/nanohybrid composites seem to be a valid alternative to traditional microhybrid composites, and at the moment, there is low-level evidence attesting a lack of their superiority.

Analysis of copy number variations reveals differences among cattle breeds

USDA-ARS?s Scientific Manuscript database

Genomic structural variation is an important and abundant source of genetic and phenotypic variation. Here we describe the first systematic and genome-wide analysis of copy number variations (CNVs) in the modern domesticated cattle using array comparative genomic hybridization (array CGH) and quanti...

Genetic architecture of natural variation in cuticular hydrocarbon composition in Drosophila melanogaster.

PubMed

Dembeck, Lauren M; Böröczky, Katalin; Huang, Wen; Schal, Coby; Anholt, Robert R H; Mackay, Trudy F C

2015-11-14

Insect cuticular hydrocarbons (CHCs) prevent desiccation and serve as chemical signals that mediate social interactions. Drosophila melanogaster CHCs have been studied extensively, but the genetic basis for individual variation in CHC composition is largely unknown. We quantified variation in CHC profiles in the D. melanogaster Genetic Reference Panel (DGRP) and identified novel CHCs. We used principal component (PC) analysis to extract PCs that explain the majority of CHC variation and identified polymorphisms in or near 305 and 173 genes in females and males, respectively, associated with variation in these PCs. In addition, 17 DGRP lines contain the functional Desat2 allele characteristic of African and Caribbean D. melanogaster females (more 5,9-C27:2 and less 7,11-C27:2, female sex pheromone isomers). Disruption of expression of 24 candidate genes affected CHC composition in at least one sex. These genes are associated with fatty acid metabolism and represent mechanistic targets for individual variation in CHC composition.

Host genetic variation impacts microbiome composition across human body sites.

PubMed

Blekhman, Ran; Goodrich, Julia K; Huang, Katherine; Sun, Qi; Bukowski, Robert; Bell, Jordana T; Spector, Timothy D; Keinan, Alon; Ley, Ruth E; Gevers, Dirk; Clark, Andrew G

2015-09-15

The composition of bacteria in and on the human body varies widely across human individuals, and has been associated with multiple health conditions. While microbial communities are influenced by environmental factors, some degree of genetic influence of the host on the microbiome is also expected. This study is part of an expanding effort to comprehensively profile the interactions between human genetic variation and the composition of this microbial ecosystem on a genome- and microbiome-wide scale. Here, we jointly analyze the composition of the human microbiome and host genetic variation. By mining the shotgun metagenomic data from the Human Microbiome Project for host DNA reads, we gathered information on host genetic variation for 93 individuals for whom bacterial abundance data are also available. Using this dataset, we identify significant associations between host genetic variation and microbiome composition in 10 of the 15 body sites tested. These associations are driven by host genetic variation in immunity-related pathways, and are especially enriched in host genes that have been previously associated with microbiome-related complex diseases, such as inflammatory bowel disease and obesity-related disorders. Lastly, we show that host genomic regions associated with the microbiome have high levels of genetic differentiation among human populations, possibly indicating host genomic adaptation to environment-specific microbiomes. Our results highlight the role of host genetic variation in shaping the composition of the human microbiome, and provide a starting point toward understanding the complex interaction between human genetics and the microbiome in the context of human evolution and disease.

Hydrogen Isotopic Systematics of Nominally Anhydrous Phases in Martian Meteorites

NASA Astrophysics Data System (ADS)

Tucker, Kera

Hydrogen isotope compositions of the martian atmosphere and crustal materials can provide unique insights into the hydrological and geological evolution of Mars. While the present-day deuterium-to-hydrogen ratio (D/H) of the Mars atmosphere is well constrained (~6 times that of terrestrial ocean water), that of its deep silicate interior (specifically, the mantle) is less so. In fact, the hydrogen isotope composition of the primordial martian mantle is of great interest since it has implications for the origin and abundance of water on that planet. Martian meteorites could provide key constraints in this regard, since they crystallized from melts originating from the martian mantle and contain phases that potentially record the evolution of the H 2O content and isotopic composition of the interior of the planet over time. Examined here are the hydrogen isotopic compositions of Nominally Anhydrous Phases (NAPs) in eight martian meteorites (five shergottites and three nakhlites) using Secondary Ion Mass Spectrometry (SIMS). This study presents a total of 113 individual analyses of H2O contents and hydrogen isotopic compositions of NAPs in the shergottites Zagami, Los Angeles, QUE 94201, SaU 005, and Tissint, and the nakhlites Nakhla, Lafayette, and Yamato 000593. The hydrogen isotopic variation between and within meteorites may be due to one or more processes including: interaction with the martian atmosphere, magmatic degassing, subsolidus alteration (including shock), and/or terrestrial contamination. Taking into consideration the effects of these processes, the hydrogen isotope composition of the martian mantle may be similar to that of the Earth. Additionally, this study calculated upper limits on the H2O contents of the shergottite and nakhlite parent melts based on the measured minimum H2O abundances in their maskelynites and pyroxenes, respectively. These calculations, along with some petrogenetic assumptions based on previous studies, were subsequently used to infer the H2O contents of the mantle source reservoirs of the depleted shergottites (200-700 ppm) and the nakhlites (10-100 ppm). This suggests that mantle source of the nakhlites is systematically drier than that of the depleted shergottites, and the upper mantle of Mars may have preserved significant heterogeneity in its H2O content. Additionally, this range of H2O contents is not dissimilar to the range observed for the Earth's upper mantle.

Spatially resolved variations in reflectivity across iron oxide thin films

NASA Astrophysics Data System (ADS)

Kelley, Chris S.; Thompson, Sarah M.; Gilks, Daniel; Sizeland, James; Lari, Leonardo; Lazarov, Vlado K.; Matsuzaki, Kosuke; LeFrançois, Stéphane; Cinque, Gianfelice; Dumas, Paul

2017-11-01

The spin polarising properties of the iron oxide magnetite (Fe3O4) make it attractive for use in spintronic devices, but its sensitivity to compositional and structural variations make it challenging to prepare reliably. Infrared microspectroscopy and modelling are used to determine the spatial variation in the chemical composition of three thin films of iron oxide; one prepared by pulsed laser deposition (PLD), one by molecular beam epitaxy (MBE) deposition of iron whilst simultaneously flowing oxygen into the chamber and one by flowing oxygen only once deposition is complete. The technique is easily able to distinguish between films which contain metallic iron and different iron oxide phases as well as spatial variations in composition across the films. The film grown by post-oxidising iron is spatially uniform but not fully oxidised, the film grown by simultaneously oxidising iron showed spatial variation in oxide composition while the film grown by PLD was spatially uniform magnetite.

Radial Mixing and Ru-Mo Isotope Systematics Under Different Accretion Scenarios

NASA Astrophysics Data System (ADS)

Fischer, R. A.; Nimmo, F.; O'Brien, D. P.

2017-12-01

The Ru-Mo isotopic compositions of inner Solar System bodies may reflect the provenance of accreted material and how it evolved with time, both of which are controlled by the accretion scenario these bodies experienced. Here we use a total of 116 N-body simulations of terrestrial planet accretion, run in the Eccentric Jupiter and Saturn (EJS), Circular Jupiter and Saturn (CJS), and Grand Tack scenarios, to model the Ru-Mo anomalies of Earth, Mars, and Theia analogues. This model starts by applying an initial step function in Ru-Mo isotopic composition, with compositions reflecting those in meteorites, and traces compositional evolution as planets accrete. The mass-weighted provenance of the resulting planets reveals more radial mixing in Grand Tack simulations than in EJS/CJS simulations, and more efficient mixing among late-accreted material than during the main phase of accretion in EJS/CJS simulations. We find that an extensive homogenous inner disk region is required to reproduce Earth's observed Ru-Mo composition. EJS/CJS simulations require a homogeneous reservoir in the inner disk extending to ≥3-4 AU (≥74-98% of initial mass) to reproduce Earth's composition, while Grand Tack simulations require a homogeneous reservoir extending to ≥3-10 AU (≥97-99% of initial mass), and likely to ≥7-10 AU. In the Grand Tack model, Jupiter's initial location (the most likely location for a discontinuity in isotopic composition) is 3.5 AU; however, this step location has only a 33% likelihood of producing an Earth with the correct Ru-Mo isotopic signature for the most plausible model conditions. Our results give the testable predictions that Mars has zero Ru anomaly and small or zero Mo anomaly, and the Moon has zero Mo anomaly. These predictions are insensitive to wide variations in parameter choices.

Re-Os isotopic evidence for an enriched-mantle source for the Noril'sk-type, ore-bearing intrusions, Siberia

USGS Publications Warehouse

Walker, R.J.; Morgan, J.W.; Horan, M.F.; Czamanske, G.K.; Krogstad, E.J.; Fedorenko, V.A.; Kunilov, V.E.

1994-01-01

Magmatic Cu-Ni sulfide ores and spatially associated ultramafic and mafic rocks from the Noril'sk I, Talnakh, and Kharaelakh intrusions are examined for Re-Os isotopic systematics. Neodymium and lead isotopic data also are reported for the ultramafic and mafic rocks. The Re-Os data for most samples indicate closed-system behavior since the ca. 250 Ma igneous crystallization age of the intrusions. There are small but significant differences in the initial osmium isotopic compositions of samples from the three intrusions. Ores from the Noril'sk I intrusion have ??Os values that vary from +0.4 to +8.8, but average +5.8. Ores from the Talnakh intrusion have ??Os values that range from +6.7 to +8.2, averaging +7.7. Ores from the Kharaelakh intrusion have ??Os values that range from +7.8 to +12.9, with an average value of +10.4. The osmium isotopic compositions of the ore samples from the Main Kharaelakh orebody exhibit minimal overlap with those for the Noril'sk I and Talnakh intrusions, indicating that these Kharaelakh ores were derived from a more radiogenic source of osmium than the other ores. Combined osmium and lead data for major orebodies in the three intrusions plot in three distinct fields, indicating derivation of osmium and lead from at least three isotopically distinct sources. Some of the variation in lead isotopic compositions may be the result of minor lower-crustal contamination. However, in contrast to most other isotopic and trace element data, Os-Pb variations are generally inconsistent with significant crustal contamination or interaction with the subcontinental lithosphere. Thus, the osmium and lead isotopic compositions of these intrusions probably reflect quite closely the compositions of their mantle source, and suggest that these two isotope systems were insensitive to lithospheric interaction. Ultramafic and mafic rocks have osmium and lead isotopic compositions that range only slightly beyond the compositions of the ores. These rocks also have relatively uniform ??{lunate}Nd values that range only from -0.8 to + 1.1. This limited variation in neodymium isotopic composition may reflect the characteristics of the mantle sources of the rocks, or it may indicate that somehow similar proportions of crust contaminated the parental melts. The osmium, lead, and neodymium isotopic data for these rocks most closely resemble the mantle sources of certain ocean island basalts (OIB), such as some Hawaiian basalts. Hence, these data are consistent with derivation of primary melts from a mantle source similar to that of some types of hotspot activity. The long-term Re/Os enrichment of this and similar mantle sources, relative to chondritic upper mantle, may reflect 1. (1) incorporation of recycled oceanic crust into the source more than 1 Ga ago, 2. (2) derivation from a mantle plume that originated at the outer core-lower mantle interface, or 3. (3) persistence of primordial stratification of rhenium and osmium in the mantle. ?? 1994.

Evolution of the inner asteroid belt: Paradigms and paradoxes from spectral studies

NASA Technical Reports Server (NTRS)

Gaffey, Michael J.

1987-01-01

Recent years have witnessed a significant increase in the sophistication of asteroidal surface material characterizations derived from spectral data. An extensive data base of moderate to high spectral resolution, visible and near-infrared asteroid spectra is now available. Interpretive methodologies and calibrations were developed to determine phase abundance and composition in olivine-pyroxene assemblages and to estimate NiFe metal abundance from such spectra. A modified version of the asteroid classifications system more closely parallels the mineralogic variations of the major inner belt asteroid types. These improvements permit several general conclusions to be drawn concerning the nature of inner belt objects; their history, and that of the inner solar system; and the relationship between the asteroids and meteorites. Essentially all large belt asteroids have or are fragments of parent bodies which have undergone strong post-accretionary heating, varying degrees of melting and magmatic differentiation, and subsequent collisional disruption. These asteroids show a systematic, but not yet well characterized, mineralogic variation with semi-major axis. This suggests that the S-type asteroid families represent relatively recent collisions onto the cores of previously disrupted parent bodies.

Evaluation of between-line variation for within-line selection against ascites in broilers.

PubMed

de Greef, K H; Kwakernaak, C; Ducro, B J; Pit, R; Gerritsen, C L

2001-01-01

Within-line opportunities for selection against ascites were studied in a data set comprising a 10-line comparison. The study attempted to reveal whether contrasts between lines provide reliable candidate traits for within-line selection. Mortality was chosen as the reference trait. As no pedigree information was available, a trait was required that related mortality to the nonmortality data. By principal component analysis, such a trait (ASC_INDIC = ascites indicator) was developed from pathology data. The composite trait ASC_INDIC ranked lines well for their mortality figures (r = 0.96), from which it was concluded that ASC_INDIC represents an underlying continuous ascites trait. Between lines, blood gas traits seemed to be the most promising traits. Within lines, performance traits appeared to be highly correlated to ascites. Comparison of within-line variation to between-line contrasts revealed considerable differences. The high correlation of the blood gas traits with mortality was not present within lines. However, although the magnitude was considerably reduced, the nature of the blood gas traits in their relationship to ascites was similar within and between lines. The study primarily demonstrates that contrasts between lines carry systematic but limited information for within-line coherence. Therefore, line contrasts must be interpreted with care when aiming to study genetic variation and coherence within lines.

The Dissolved Ca Isotope Composition of Himalayan-Tibetan Waters

NASA Astrophysics Data System (ADS)

Tipper, E. T.; Galy, A.; Bickle, M. J.

2004-12-01

Determining the relative proportions of carbonate versus silicate weathering in the Himalaya is important for understanding the long-term atmospheric CO2 budget and the marine Sr isotope record. 87Sr/86Sr is not a straightforward proxy of carbonate to silicate weathering in the Himalaya and up to 50% of the dissolved Ca may be removed by the precipitation of secondary calcite. Ca isotopes have the potential to constrain the relative inputs of carbonates to silicates and incongruent dissolution processes in the weathering environment. Ca is the major cation carried by rivers. Thirty four Himalayan rock and water samples from the Nepal Himalaya and Tibet have been analysed for 44/42Ca and 43/42Ca on a Nu-Instruments Multiple Collector -ICP-MS. Unlike the 44/40Ca ratio the 44/42Ca is not susceptible to excess 40Ca production from the decay of K. All samples lie on a single mass fractionation line. There is a total range of 0.4 \\permil variation in \\delta44Ca with values from 0.63 \\permil - 0.21 \\permil relative to the SRM915a standard. This is comparable to that already reported with \\delta44/40Ca for small catchments and global rivers. Small first order catchments from each of the main lithotectonic units of the Himalaya have been analysed to examine the effect of lithology on dissolved Ca isotopic composition. In agreement with previous studies elsewhere there is little correlation between source rock and dissolved composition for small rivers spanning a range of source rock from limestone to various silicates and covering a vegetation range from temperate semi-desert to jungle. \\delta44Ca is not correlated with 87Sr/86Sr or Na/Ca ratios confirming that source rock composition is not the dominant control on the observed range in \\delta44Ca. A time-series has been examined for the Marsyandi River, central Nepal. In spite of significant systematic variations in major element chemistry including Ca concentration and 87Sr/86Sr the variations in \\delta44Ca are limited to 0.16 \\permil. Either there is only a single isotopic source of Ca or the \\delta44Ca is controlled by incongruent dissolution processes. The most important incongruent process to affect the Ca budget is the precipitation of pedogenic carbonate. Such incongruent processes should be detectable in the Ca-isotope budget.

Polymerization Stress Development in Dental Composites: Effect of Cavity Design Factor

PubMed Central

Antonucci, Joseph M.; Giuseppetti, Anthony A.; O’Donnell, Justin N.R.; Schumacher, Gary E.; Skrtic, Drago

2009-01-01

The objective of the study was to assess the effect of the cavity design factor (C-factor) on polymerization stress development (PSD) in resin composites. An experimental resin (BT resin) was prepared, which contained 2,2-bis[p-(2’-hydroxy-3’-methacryloxypropoxy)phenylene]propane (B) and triethylene glycol dimethacrylate (T) in 1:1 mass ratio, and an activator for visible light polymerization. An experimental composite with demonstrated remineralizing potential was also formulated by inclusion into the BT resin of zirconia-hybridized amorphous calcium phosphate (ACP) filler at a mass fraction of 40 % (BT/ACP composite). A commercial glass-filled composite (TPH) was used as a control. To assess the effect of the test geometry on PSD, C-factor was systematically varied between 0.8 and 6.0 by varying the height of the cylindrical composite specimens. The measured PSD values obtained by cantilever beam tensometry for specimens with variable C-factors were normalized for mass to specimens with a C-factor of 1.33 (h=2.25 mm) as controls to give calculated PSD values. Degrees of vinyl conversions (DC) attained in the TPH control and in the experimental BT/ACP composites were measured by near-infrared spectroscopy. In both the TPH and BT/ACP composite series, PSDcalc increased with the increasing C-factor, confirming the hypothesis that the C-factor value influences PSD values. The higher PSDmeas and PSDcalc values for the experimental BT/ACP composite compared to the commercial TPH composite probably reflect differences in the type and mass of the resin and filler phases in the two types of composite. These differences also account for the observed variation (21 %) in DC attained in a BT/ACP composite 2 h after cure (69.5 %) and in the DC of the TPH composite (57.5 %) having the same C-factor. The cavity design factor seems to play a key role in influencing the PSD of bonded composites, but other factors such as composite mass and composition also must be considered for their effects on PSD. PMID:26413236

Bacterial community variation in human body habitats across space and time.

PubMed

Costello, Elizabeth K; Lauber, Christian L; Hamady, Micah; Fierer, Noah; Gordon, Jeffrey I; Knight, Rob

2009-12-18

Elucidating the biogeography of bacterial communities on the human body is critical for establishing healthy baselines from which to detect differences associated with diseases. To obtain an integrated view of the spatial and temporal distribution of the human microbiota, we surveyed bacteria from up to 27 sites in seven to nine healthy adults on four occasions. We found that community composition was determined primarily by body habitat. Within habitats, interpersonal variability was high, whereas individuals exhibited minimal temporal variability. Several skin locations harbored more diverse communities than the gut and mouth, and skin locations differed in their community assembly patterns. These results indicate that our microbiota, although personalized, varies systematically across body habitats and time; such trends may ultimately reveal how microbiome changes cause or prevent disease.

Polarization Coupling in Ferroelectric Multilayers as a Function of Interface Charge Concentration

NASA Astrophysics Data System (ADS)

Okatan, Mahmut; Mantese, Joseph; Alpay, Pamir

2009-03-01

Intriguing properties of multilayered and graded ferroelectrics follow from the electrostatic and electromechanical interactions. The strength of the interlayer coupling depends on the concentration of interfacial defects with short-range local electrostatic fields. Defects may locally relax polarization differences and thus reduce the commensurate bound charge concentration at the interlayer interfaces. In this talk, we develop a theoretical analysis based on non-linear thermodynamics coupled with basic electrostatic relations to understand the role of charge compensation at the interlayer interfaces. The results show multilayered ferroelectrics with systematic variations in the composition may display a colossal dielectric response depending upon the interlayer electrostatic interactions. It is expected that other properties such as the pyroelectric and piezoelectric response will yield concomitant increases through the dielectric permittivity.

Bacterial Community Variation in Human Body Habitats Across Space and Time

PubMed Central

Costello, Elizabeth K.; Lauber, Christian L.; Hamady, Micah; Fierer, Noah; Gordon, Jeffrey I.; Knight, Rob

2010-01-01

Elucidating the biogeography of bacterial communities on the human body is critical for establishing healthy baselines from which to detect differences associated with diseases. To obtain an integrated view of the spatial and temporal distribution of the human microbiota, we surveyed bacteria from up to 27 sites in 7–9 healthy adults on four occasions. We found that community composition was determined primarily by body habitat. Within habitats, interpersonal variability was high, while individuals exhibited minimal temporal variability. Several skin locations harbored more diverse communities than the gut and mouth, and skin locations differed in their community assembly patterns. These results indicate that our microbiota, although personalized, varies systematically across body habitats and time: such trends may ultimately reveal how microbiome changes cause or prevent disease. PMID:19892944

Partition coefficients for REE between garnets and liquids - Implications of non-Henry's Law behaviour for models of basalt origin and evolution

NASA Technical Reports Server (NTRS)

Harrison, W. J.

1981-01-01

An experimental investigation of Ce, Sm and Tm rare earth element (REE) partition coefficients between coexisting garnets (both natural and synthetic) and hydrous liquids shows that Henry's Law may not be obeyed over a range of REE concentrations of geological relevance. Systematic differences between the three REE and the two garnet compositions may be explained in terms of the differences between REE ionic radii and those of the dodecahedral site into which they substitute, substantiating the Harrison and Wood (1980) model of altervalent substitution. Model calculations demonstrate that significant variation can occur in the rare earth contents of melts produced from a garnet lherzolite, if Henry's Law partition coefficients do not apply for the garnet phase.

Potable groundwater quality in some villages of Haryana, India: focus on fluoride.

PubMed

Bishnoi, Mukul; Arora, Shalu

2007-04-01

The fluoride concentration in ground water was determined in ten villages of Rohtak district of Haryana state (India). The fluoride concentration in the underground water of these villages varied from 0.034-2.09 mg/l. Various other water quality parameters, viz., pH, electrical conductivity, total dissolved salts, total hardness, total alkalinity sodium, potassium, calcium, magnesium, carbonate, bicarbonate, chloride and sulfate were also measured. A systematic calculation of correlation coefficients among different physicochemical parameters indicated considerable variations among the analyzed samples with respect to their chemical composition. Majority of the samples do not comply with Indian as well as WHO standards for most of the water quality parameters measured. Overall water quality was found unsatisfactory for drinking purposes. Fluoride content was higher than permissible limit in 50% samples.

Thin Layer Chromatographic Resolution of Some β-adrenolytics and a β2-Agonist Using Bovine Serum Albumin as Chiral Additive in Stationary Phase.

PubMed

Malik, Poonam; Bhushan, Ravi

2018-01-01

Direct enantiomeric resolution of commonly used five racemic β-adrenolytics, namely, bisoprolol, atenolol, propranolol, salbutamol and carvedilol has been achieved by thin layer chromatography using bovine serum albumin (BSA) as chiral additive in stationary phase. Successful resolution of the enantiomers of all racemic β-adrenolytics was achieved by use of different composition of simple organic solvents having no buffer or inorganic ions. The effect of variation in pH, temperature, amount of BSA as the additive, and composition of mobile phase on resolution was systematically studied. Spots were visualized in iodine vapors. Native enantiomers for each of the five analytes were isolated and identified and their elution order was determined. The limit of detection was found to be 0.7, 1.2, 0.84, 1.6 and 0.9 μg (per spot) for each enantiomer of bisoprolol, atenolol, propranolol, salbutamol and carvedilol, respectively. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Strong room-temperature ultraviolet to red excitons from inorganic organic-layered perovskites, (MX4 (M=Pb, Sn, Hg; X=I-, Br-)

NASA Astrophysics Data System (ADS)

Ahmad, Shahab; Prakash, G. Vijaya

2014-01-01

Many varieties of layered inorganic-organic (IO) perovskite of type (MX4 (where R: organic moiety, M: divalent metal, and X: halogen) were successfully fabricated and characterized. X-ray diffraction data suggest that these inorganic and organic structures are alternatively stacked up along c-axis, where inorganic mono layers are of extended corner-shared MX6 octahedra and organic spacers are the bi-layers of organic entities. These layered perovskites show unusual room-temperature exciton absorption and photoluminescence due to the quantum and dielectric confinement-induced enhancement in the exciton binding energies. A wide spectral range of optical exciton tunability (350 to 600 nm) was observed experimentally from systematic compositional variation in (i) divalent metal ions (M=Pb, Sn, Hg), (ii) halides (X=I and Br-), and (iii) organic moieties (R). Specific photoluminescence features are due to the structure of the extended MX42- network and the eventual electronic band structure. The compositionally dependent photoluminescence of these IO hybrids could be useful in various photonic and optoelectronic devices.

Chemical composition and osmium-isotope systematics of primary and secondary PGM assemblages from high-Mg chromitite of the Nurali lherzolite massif, the South Urals, Russia

NASA Astrophysics Data System (ADS)

Malitch, K. N.; Anikina, E. V.; Badanina, I. Yu.; Belousova, E. A.; Pushkarev, E. V.; Khiller, V. V.

2016-01-01

The isotopic and geochemical characteristics of PGE mineralization in high-Mg chromitite from the banded dunite-wehrlite-clinopyroxenite complex of the Nurali lherzolite massif, the South Urals, Russia is characterized for the first time. Electron microprobe analysis and LA MC-ICP-MS mass spectrometry are used for studying Cr-spinel and platinum-group minerals (PGM). Two processes synchronously develop in high-Mg chromitite subject to metamorphism: (1) the replacement of Mg-Al-rich Cr-spinel, orthopyroxene, and diopside by chromite, Cr-amphibole, chlorite, and garnet; (2) the formation of a secondary mineral assemblage consisting of finely dispersed ruthenium or Ru-hexaferrum aggregate and silicate-oxide or silicate matter on the location of primary Ru-Os-sulfides of the laurite-erlichmanite solid solution series. Similar variations of Os-isotopic composition in both primary and secondary PGM assemblages are evidence for the high stability of the Os isotope system in PGM and for the possibility of using model 187Os/188Os ages in geodynamic reconstructions.

Advances in plant virus evolution: translating evolutionary insights into better disease management.

PubMed

Acosta-Leal, R; Duffy, S; Xiong, Z; Hammond, R W; Elena, S F

2011-10-01

Recent studies in plant virus evolution are revealing that genetic structure and behavior of virus and viroid populations can explain important pathogenic properties of these agents, such as host resistance breakdown, disease severity, and host shifting, among others. Genetic variation is essential for the survival of organisms. The exploration of how these subcellular parasites generate and maintain a certain frequency of mutations at the intra- and inter-host levels is revealing novel molecular virus-plant interactions. They emphasize the role of host environment in the dynamic genetic composition of virus populations. Functional genomics has identified host factors that are transcriptionally altered after virus infections. The analyses of these data by means of systems biology approaches are uncovering critical plant genes specifically targeted by viruses during host adaptation. Also, a next-generation resequencing approach of a whole virus genome is opening new avenues to study virus recombination and the relationships between intra-host virus composition and pathogenesis. Altogether, the analyzed data indicate that systematic disruption of some specific parameters of evolving virus populations could lead to more efficient ways of disease prevention, eradication, or tolerable virus-plant coexistence.

Systematic approach to preparing ceramic-glass composites with high translucency for dental restorations.

PubMed

Yoshimura, Humberto N; Chimanski, Afonso; Cesar, Paulo F

2015-10-01

Ceramic composites are promising materials for dental restorations. However, it is difficult to prepare highly translucent composites due to the light scattering that occurs in multiphase ceramics. The objective of this work was to verify the effectiveness of a systematic approach in designing specific glass compositions with target properties in order to prepare glass infiltrated ceramic composites with high translucency. First it was necessary to calculate from literature data the viscosity of glass at the infiltration temperature using the SciGlass software. Then, a glass composition was designed for targeted viscosity and refractive index. The glass of the system SiO2-B2O3-Al2O3-La2O3-TiO2 prepared by melting the oxide raw materials was spontaneously infiltrated into porous alumina preforms at 1200°C. The optical properties were evaluated using a refractometer and a spectrophotometer. The absorption and scattering coefficients were calculated using the Kubelka-Munk model. The light transmittance of prepared composite was significantly higher than a commercial ceramic-glass composite, due to the matching of glass and preform refractive indexes which decreased the scattering, and also to the decrease in absorption coefficient. The proposed systematic approach was efficient for development of glass infiltrated ceramic composites with high translucency, which benefits include the better aesthetic performance of the final prosthesis. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Earth's early atmosphere as seen from carbon and nitrogen isotopic analysis of Archean sediments

NASA Technical Reports Server (NTRS)

Gibson, E. K., Jr.; Carr, L. P.; Gilmour, I.; Pillinger, C. T.

1986-01-01

The origin and evolution of the Earth's early atmosphere has long been a topic of great interest but determination of actual compositions over geologic time is a difficult problem. However, recent systematic studies of stromatolite deposits (Precambrian Paleobiology Research Group) has extended our knowledge of Archean ecosystems. It has been shown that many stromatolite deposits have undergone negligible alteration since their time of formation. The discovery of primary fluid inclusions within unaltered 3.5 b.y. old Archiean sediments and the observation that the 3.3 b.y. old Barberton cherts have remained closed to argon loss and have not been subjected to thermal metamorphism suggests that an opportunity exists for the direct measurement of the volatile constituents present at their time of formation. Of primary interest to this study was the possibility that the stromatolites and other Archean sediments might retain a vestige of the atmosphere and thus afford an indication of the variations in carbon dioxide and nitrogen isotopic compositions with time. A suite of essentially unaltered Archean stromatolites and the cherts of different ages and geologic sites have been analyzed for their trapped carbon dioxide and nitrogen compositions by the stepped combustion extraction tech nique utilizing static mass spectrometers for the isotope measurements.

Super-cool paints: optimizing composition with a modified four-flux model

NASA Astrophysics Data System (ADS)

Gali, Marc A.; Arnold, Matthew D.; Gentle, Angus R.; Smith, Geoffrey B.

2017-09-01

The scope for maximizing the albedo of a painted surface to produce low cost new and retro-fitted super-cool roofing is explored systematically. The aim is easy to apply, low cost paint formulations yielding albedos in the range 0.90 to 0.95. This requires raising the near-infrared (NIR) spectral reflectance into this range, while not reducing the more easily obtained high visible reflectance values. Our modified version of the four-flux method has enabled results on more complex composites. Key parameters to be optimized include; fill factors, particle size and material, using more than one mean size, thickness, substrate and binder materials. The model used is a variation of the classical four-flux method that solves the energy transfer problem through four balance differential equations. We use a different approach to the characteristic parameters to define the absorptance and scattering of the complete composite. This generalization allows extension to inclusion of size dispersion of the pigment particle and various binder resins, including those most commonly in use based on acrylics. Thus, the pigment scattering model has to take account of the matrix having loss in the NIR. A paint ranking index aimed specifically at separating paints with albedo above 0.80 is introduced representing the fraction of time at a sub-ambient temperature.

Clinical effects of probiotics in cystic fibrosis patients: A systematic review.

PubMed

Van Biervliet, Stephanie; Declercq, Dimitri; Somerset, Shawn

2017-04-01

Cystic fibrosis (CF) is characterised by a build-up of thick, intransient mucus linings of the digestive and respiratory mucosa, which disrupts digestive system functioning and microbiota composition. In view of the potential for probiotics to enhance microbiota composition in other contexts, this study investigated the current evidence for probiotics as an adjunct to usual therapy for CF. Electronic clinical databases were interrogated for human randomised, controlled, intervention trials (1985-2015) testing the effects of probiotics on clinical endpoints in CF were reviewed. From 191 articles identified in initial searches, six studies met the critical inclusion criteria, and were reviewed in detail. These studies varied in size (n = 22 to 61) but were generally small and showed substantial diversity in protocol, specific probiotic species used and range of clinical outcomes measured. Probiotic administration showed beneficial effects on fecal calprotectin levels, pulmonary exacerbation risk, and quality of life indicators. In one study, such changes were associated with variations in gut microbiota composition. Despite encouraging preliminary results, the limited number of small and highly varied studies to date do not justify the addition of probiotics as an adjunct to current CF treatment protocols. Importantly, very minimal adverse effects of probiotics have been reported. Copyright © 2017 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.

Significant Beneficial Association of High Dietary Selenium Intake with Reduced Body Fat in the CODING Study

PubMed Central

Wang, Yongbo; Gao, Xiang; Pedram, Pardis; Shahidi, Mariam; Du, Jianling; Yi, Yanqing; Gulliver, Wayne; Zhang, Hongwei; Sun, Guang

2016-01-01

Selenium (Se) is a trace element which plays an important role in adipocyte hypertrophy and adipogenesis. Some studies suggest that variations in serum Se may be associated with obesity. However, there are few studies examining the relationship between dietary Se and obesity, and findings are inconsistent. We aimed to investigate the association between dietary Se intake and a panel of obesity measurements with systematic control of major confounding factors. A total of 3214 subjects participated in the study. Dietary Se intake was determined from the Willett food frequency questionnaire. Body composition was measured using dual-energy X-ray absorptiometry. Obese men and women had the lowest dietary Se intake, being 24% to 31% lower than corresponding normal weight men and women, classified by both BMI and body fat percentage. Moreover, subjects with the highest dietary Se intake had the lowest BMI, waist circumference, and trunk, android, gynoid and total body fat percentages, with a clear dose-dependent inverse relationship observed in both gender groups. Furthermore, significant negative associations discovered between dietary Se intake and obesity measurements were independent of age, total dietary calorie intake, physical activity, smoking, alcohol, medication, and menopausal status. Dietary Se intake alone may account for 9%–27% of the observed variations in body fat percentage. The findings from this study strongly suggest that high dietary Se intake is associated with a beneficial body composition profile. PMID:26742059

Composite Material Testing Data Reduction to Adjust for the Systematic 6-DOF Testing Machine Aberrations

Treesearch

Athanasios lliopoulos; John G. Michopoulos; John G. C. Hermanson

2012-01-01

This paper describes a data reduction methodology for eliminating the systematic aberrations introduced by the unwanted behavior of a multiaxial testing machine, into the massive amounts of experimental data collected from testing of composite material coupons. The machine in reference is a custom made 6-DoF system called NRL66.3 and developed at the NAval...

Mg and 18O Variations in the Shell of the Chilean Gastropod Concholepas concholepas Reflect SST and Growth Rate variations

NASA Astrophysics Data System (ADS)

Guzman, N.; Lazareth, C. E.; Poitrasson, F.; Cuif, J.; Ortlieb, L.

2004-12-01

To validate the use of fossil mollusc shells as recorders of environmental conditions, a primary calibration study was carried out on modern shells of the Chilean gastropod Concholepas concholepas, the so-called southern hemisphere abalone which is particularly abundant in Holocene archaeological sites. Organisms were maintained in culture tanks and feed with live mytilids. The sea water temperature in the tank was recorded every half-an-hour by an automatic device. The experiment lasted several months. Periodical marking with calcein provided a precise chronological control of the shell growth. Thus, well-dated high resolution chemical profiles could be directly compared with temperatures during shell formation. Geochemical analyses of the calcite layers include Mg, Sr and 16O/18O composition. Trace elements were analysed using Laser Ablation ICP-MS and Electron Microprobe while stable isotopes were measured on a Secondary Ion Mass spectrometry (SIMS). The shell growth rate during two months of formation varied between 30 and 140 µm/day which allows us to reach a temporal resolution for chemical profiles between a few hours and three days. The growth rate variations do not seem to be related to temperature fluctuations. Only Mg content was analytically reproducible and showed significant variations across the shells. The Mg high-resolution profiles display a grossly sinusoidal shape. Shells from different sites along the coasts of Chile showed mean Mg contents of 300 ppm and 500 ppm for mean temperatures of 17 and 20° C, respectively. This suggests a gross correlation between Mg and temperature. However, high resolution Mg results do not show an exact fitting neither with temperature nor with growth rates. Other parameters, like shell ageing as suggested by an amplitude increase observed near the edge of one of the shells, or other complex biological factors, may influence Mg incorporation into the shell. \\delta 18O values of the calcite vary between -1,5 and 2,0 \\permil for a temperature range between 17 and 22° C. Growth rate variations seem to be an important factor affecting the oxygen isotopic ratio within shells. When growth rate variations are limited, \\delta 18O and temperature are well correlated. The study confirms that, like for all biogenic carbonates, elemental and isotopic composition of the calcite layer of this gastropod, should not be used in paleoenvironmental reconstructions without detailed calibration experiments, and must systematically include precise growth rate analyses. The growth rhythms, which vary under the double influence of environmental and biological factors, are of paramount importance in the relationship between environmental parameters and geochemical composition of the growth layers of the shells. Work supported by "CONCHAS" Project (PNEDC).

Altitude and intensity characteristics of parametric instability excited by an HF pump wave near the fifth electron harmonic

NASA Astrophysics Data System (ADS)

Jun, WU; Jian, WU; M, T. RIETVELD; I, HAGGSTROM; Haisheng, ZHAO; Zhengwen, XU

2017-12-01

An ionospheric heating experiment involving an O mode pump wave was carried out at European Incoherent Scatter Scientific Association site in Tromsø. The observation of the ultra high frequency radar illustrates the systematic variations of the enhanced ion line and plasma line in altitude and intensity as a function of the pump frequency. The analysis shows that those altitude variations are due to the thermal effect, and the intensity variations of the enhanced ion line are dependent on whether or not the enhanced ion acoustic wave satisfy the Bragg condition of radar. Moreover, a prediction that if the enhancement in electron temperature is suppressed, those systematic variations will be absent, is given.

Continental igneous rock composition: A major control of past global chemical weathering

PubMed Central

Bataille, Clément P.; Willis, Amy; Yang, Xiao; Liu, Xiao-Ming

2017-01-01

The composition of igneous rocks in the continental crust has changed throughout Earth’s history. However, the impact of these compositional variations on chemical weathering, and by extension on seawater and atmosphere evolution, is largely unknown. We use the strontium isotope ratio in seawater [(87Sr/86Sr)seawater] as a proxy for chemical weathering, and we test the sensitivity of (87Sr/86Sr)seawater variations to the strontium isotopic composition (87Sr/86Sr) in igneous rocks generated through time. We demonstrate that the 87Sr/86Sr ratio in igneous rocks is correlated to the epsilon hafnium (εHf) of their hosted zircon grains, and we use the detrital zircon record to reconstruct the evolution of the 87Sr/86Sr ratio in zircon-bearing igneous rocks. The reconstructed 87Sr/86Sr variations in igneous rocks are strongly correlated with the (87Sr/86Sr)seawater variations over the last 1000 million years, suggesting a direct control of the isotopic composition of silicic magmatism on (87Sr/86Sr)seawater variations. The correlation decreases during several time periods, likely reflecting changes in the chemical weathering rate associated with paleogeographic, climatic, or tectonic events. We argue that for most of the last 1000 million years, the (87Sr/86Sr)seawater variations are responding to changes in the isotopic composition of silicic magmatism rather than to changes in the global chemical weathering rate. We conclude that the (87Sr/86Sr)seawater variations are of limited utility to reconstruct changes in the global chemical weathering rate in deep times. PMID:28345044

Re-Os systematics of komatiites and komatiitic basalts at Dundonald Beach, Ontario, Canada: Evidence for a complex alteration history and implications of a late-Archean chondritic mantle source

NASA Astrophysics Data System (ADS)

Gangopadhyay, A.; Sproule, R. A.; Walker, R. J.; Lesher, C.

2004-12-01

Re-Os concentrations and isotopic compositions have been examined in one komatiite unit and one komatiitic basalt unit at Dundonald Beach, which is part of the spatially-extensive 2.7 Ga Kidd-Munro volcanic assemblage in the Abitibi greenstone belt, Ontario, Canada. The komatiitic rocks in this locality record at least three episodes of alteration of Re-Os elemental and isotope systematics. First, an average of 40% and as much as 75% Re was lost due to shallow degassing during eruption and/or hydrothermal leaching during or immediately after the lava emplacement. Second, the Re-Os isotope systematics of the rocks with 187Re/188Os ratios >1 were reset at ˜2.5 Ga, most likely due to a regional metamorphic event. Finally, there is evidence for relatively recent gain and loss of Re. The variations in Os concentrations in the Dundonald komatiites yield a relative bulk distribution coefficient for Os (DOs solid/liquid) of 2-4, consistent with those obtained for stratigraphically-equivalent komatiites in the nearby Alexo area and in Munro Township. This suggests that Os was moderately compatible during crystal-liquid fractionation of the magma parental to the Kidd-Munro komatiitic rocks. Furthermore, whole-rock samples and chromite separates with low 187Re/188Os ratios (<1) yield a precise chondritic average initial 187Os/188Os ratio of 0.1083 ± 0.0006 (\\gammaOs = 0.0 ± 0.6). The chondritic initial Os isotopic composition of the mantle source for the Dundonald rocks is consistent with that determined for komatiites in the Alexo area and in Munro Township. Our Os isotope results for the Dundonald komatiitic rocks, combined with those in the Alexo and Pyke Hill areas suggest that the mantle source region for the Kidd- Munro volcanic assemblage had evolved along a long-term chondritic Os isotopic trajectory until their eruption at ˜2.7 Ga. The chondritic initial Os isotopic composition of the Kidd-Munro komatiites is indistinguishable from that of the projected contemporaneous convective upper mantle. The uniform chondritic Os isotopic composition of the ˜2.7 Ga mantle source for the Kidd-Munro komatiites contrasts with the typical large-scale Os isotopic heterogeneity in the mantle sources for komatiites from the Gorgona Island, present-day ocean island basalts or arc-related lavas. This suggests a significantly more homogeneous mantle source in the Archean compared to the presentday mantle.

Clinical performance of direct versus indirect composite restorations in posterior teeth: A systematic review.

PubMed

Azeem, Rubeena Abdul; Sureshbabu, Nivedhitha Malli

2018-01-01

Composite resin, serves as esthetic alternative to amalgam and cast restorations. Posterior teeth can be restored using direct or indirect composite restorations. The selection between direct and indirect technique is a clinically challenging decision-making process. Most important influencing factor is the amount of remaining tooth substance. The aim of this systematic review was to compare the clinical performance of direct versus indirect composite restorations in posterior teeth. The databases searched included PubMed CENTRAL (until July 2015), Medline, and Cochrane Database of Systematic Reviews. The bibliographies of clinical studies and reviews identified in the electronic search were analyzed to identify studies which were published outside the electronically searched journals. The primary outcome measure was evaluation of the survival of direct and indirect composite restorations in posterior teeth. This review included thirteen studies in which clinical performance of various types of direct and indirect composite restorations in posterior teeth were compared. Out of the thirteen studies which were included seven studies had a high risk of bias and five studies had a moderate risk of bias. One study having a low risk of bias, concluded that there was no significant difference between direct and indirect technique. However, the available evidence revealed inconclusive results. Further research should focus on randomized controlled trials with long term follow-up to give concrete evidence on the clinical performce of direct and indirect composite restorations.

Description of nuclear systems with a self-consistent configuration-mixing approach. II. Application to structure and reactions in even-even s d -shell nuclei

NASA Astrophysics Data System (ADS)

Robin, C.; Pillet, N.; Dupuis, M.; Le Bloas, J.; Peña Arteaga, D.; Berger, J.-F.

2017-04-01

Background: The variational multiparticle-multihole configuration mixing approach to nuclei has been proposed about a decade ago. While the first applications followed rapidly, the implementation of the full formalism of this method has only been recently completed and applied in C. Robin, N. Pillet, D. Peña Arteaga, and J.-F. Berger, [Phys. Rev. C 93, 024302 (2016)], 10.1103/PhysRevC.93.024302 to 12C as a test-case. Purpose: The main objective of the present paper is to carry on the study that was initiated in that reference, in order to put the variational multiparticle-multihole configuration mixing method to more stringent tests. To that aim we perform a systematic study of even-even s d -shell nuclei. Method: The wave function of these nuclei is taken as a configuration mixing built on orbitals of the s d -shell, and both the mixing coefficients of the nuclear state and the single-particle wave functions are determined consistently from the same variational principle. As in the previous works, the calculations are done using the D1S Gogny force. Results: Various ground-state properties are analyzed. In particular, the correlation content and composition of the wave function as well as the single-particle orbitals and energies are examined. Binding energies and charge radii are also calculated and compared to experiment. The description of the first excited state is also examined and the corresponding transition densities are used as input for the calculation of reaction processes such as inelastic electron and proton scattering. Special attention is paid to the effect of the optimization of the single-particle states consistently with the correlations of the system. Conclusions: The variational multiparticle-multihole configuration mixing approach is systematically applied to the description of even-even s d -shell nuclei. Globally, the results are satisfying and encouraging. In particular, charge radii and excitation energies are nicely reproduced. However, the chosen valence-space truncation scheme precludes achieving maximum collectivity in the studied nuclei. Further refinement of the method and a better-suited interaction are necessary to remedy this situation.

Defining Flare in Osteoarthritis of the Hip and Knee: A Systematic Literature Review - OMERACT Virtual Special Interest Group.

PubMed

Cross, Marita; Dubouis, Ludovic; Mangin, Matthieu; Hunter, David J; March, Lyn; Hawker, Gillian; Guillemin, Francis

2017-12-01

Beyond the exacerbation of pain in describing a flare in osteoarthritis (OA), patients and health professionals add other elements that deserve to be fully elucidated, such as effusion, swelling, and mobility limitation. To define and conceptualize the construct flare in OA, the objective was to identify the key variables, or symptoms, that worsen, and to clarify how these variables are described in the literature by patients and clinicians. A systematic review of the literature was conducted in Medline and PsychINFO. In brief, the search terms used were "osteoarthritis," "knee," "hip," and "flare." Specific characteristics of included studies were identified, including the type of study design, type of flare assessed, how the flare developed, and what definition of flare was used, including whether the definition was based on qualitative or quantitative analysis. Pain was the major factor in the definition of flare within these studies. Four components of flare were identified: pain, other factors, composite criteria, and global assessment. While the majority of studies reported flare as an increase in pain using standardized outcome measures, only 1 study reported the antecedents and consequences of a pain flare using qualitative methods. The use of flare as an outcome or inclusion criterion in rheumatology trials is a common occurrence; however, this review highlights the wide variation in the definitions of OA flare currently in use and the emphasis on the measurement of pain. This variation in definition does not allow for direct comparison between trials and limits interpretation of evidence.

Gene networks underlying convergent and pleiotropic phenotypes in a large and systematically-phenotyped cohort with heterogeneous developmental disorders.

PubMed

Andrews, Tallulah; Meader, Stephen; Vulto-van Silfhout, Anneke; Taylor, Avigail; Steinberg, Julia; Hehir-Kwa, Jayne; Pfundt, Rolph; de Leeuw, Nicole; de Vries, Bert B A; Webber, Caleb

2015-03-01

Readily-accessible and standardised capture of genotypic variation has revolutionised our understanding of the genetic contribution to disease. Unfortunately, the corresponding systematic capture of patient phenotypic variation needed to fully interpret the impact of genetic variation has lagged far behind. Exploiting deep and systematic phenotyping of a cohort of 197 patients presenting with heterogeneous developmental disorders and whose genomes harbour de novo CNVs, we systematically applied a range of commonly-used functional genomics approaches to identify the underlying molecular perturbations and their phenotypic impact. Grouping patients into 408 non-exclusive patient-phenotype groups, we identified a functional association amongst the genes disrupted in 209 (51%) groups. We find evidence for a significant number of molecular interactions amongst the association-contributing genes, including a single highly-interconnected network disrupted in 20% of patients with intellectual disability, and show using microcephaly how these molecular networks can be used as baits to identify additional members whose genes are variant in other patients with the same phenotype. Exploiting the systematic phenotyping of this cohort, we observe phenotypic concordance amongst patients whose variant genes contribute to the same functional association but note that (i) this relationship shows significant variation across the different approaches used to infer a commonly perturbed molecular pathway, and (ii) that the phenotypic similarities detected amongst patients who share the same inferred pathway perturbation result from these patients sharing many distinct phenotypes, rather than sharing a more specific phenotype, inferring that these pathways are best characterized by their pleiotropic effects.

Determinants of Tree Assemblage Composition at the Mesoscale within a Subtropical Eucalypt Forest

PubMed Central

Hero, Jean-Marc; Butler, Sarah A.; Lollback, Gregory W.; Castley, James G.

2014-01-01

A variety of environmental processes, including topography, edaphic and disturbance factors can influence vegetation composition. The relative influence of these patterns has been known to vary with scale, however, few studies have focused on environmental drivers of composition at the mesoscale. This study examined the relative importance of topography, catchment flow and soil in influencing tree assemblages in Karawatha Forest Park; a South-East Queensland subtropical eucalypt forest embedded in an urban matrix that is part of the Terrestrial Ecosystem Research Network South-East Queensland Peri-urban SuperSite. Thirty-three LTER plots were surveyed at the mesoscale (909 ha), where all woody stems ≥1.3 m high rooted within plots were sampled. Vegetation was divided into three cohorts: small (≥1–10 cm DBH), intermediate (≥10–30 cm DBH), and large (≥30 cm DBH). Plot slope, aspect, elevation, catchment area and location and soil chemistry and structure were also measured. Ordinations and smooth surface modelling were used to determine drivers of vegetation assemblage in each cohort. Vegetation composition was highly variable among plots at the mesoscale (plots systematically placed at 500 m intervals). Elevation was strongly related to woody vegetation composition across all cohorts (R2: 0.69–0.75). Other topographic variables that explained a substantial amount of variation in composition were catchment area (R2: 0.43–0.45) and slope (R2: 0.23–0.61). Soil chemistry (R2: 0.09–0.75) was also associated with woody vegetation composition. While species composition differed substantially between cohorts, the environmental variables explaining composition did not. These results demonstrate the overriding importance of elevation and other topographic features in discriminating tree assemblage patterns irrespective of tree size. The importance of soil characteristics to tree assemblages was also influenced by topography, where ridge top sites were typically drier and had lower soil nutrient levels than riparian areas. PMID:25501866

The presence of accessory cusps in chimpanzee lower molars is consistent with a patterning cascade model of development

PubMed Central

Skinner, Matthew M; Gunz, Philipp

2010-01-01

Tooth crown morphology is of primary importance in fossil primate systematics and understanding the developmental basis of its variation facilitates phenotypic analyses of fossil teeth. Lower molars of species in the chimp/human clade (including fossil hominins) possess between four and seven cusps and this variability has been implicated in alpha taxonomy and phylogenetic systematics. What is known about the developmental basis of variation in cusp number – based primarily on experimental studies of rodent molars – suggests that cusps form under a morphodynamic, patterning cascade model involving the iterative formation of enamel knots. In this study we test whether variation in cusp 6 (C6) presence in common chimpanzee and bonobo lower molars (n = 55) is consistent with predictions derived from the patterning cascade model. Using microcomputed tomography we imaged the enamel-dentine junction of lower molars and used geometric morphometrics to examine shape variation in the molar crown correlated with variation in C6 presence (in particular the size and spacing of the dentine horns). Results indicate that C6 presence is consistent with predictions of a patterning cascade model, with larger molars exhibiting a higher frequency of C6 and with the location and size of later-forming cusps correlated with C6 variation. These results demonstrate that a patterning cascade model is appropriate for interpreting cusp variation in Pan and have implications for cusp nomenclature and the use of accessory cusp morphology in primate systematics. PMID:20629983

Relative impact of key sources of systematic noise in Affymetrix and Illumina gene-expression microarray experiments.

PubMed

Kitchen, Robert R; Sabine, Vicky S; Simen, Arthur A; Dixon, J Michael; Bartlett, John M S; Sims, Andrew H

2011-12-01

Systematic processing noise, which includes batch effects, is very common in microarray experiments but is often ignored despite its potential to confound or compromise experimental results. Compromised results are most likely when re-analysing or integrating datasets from public repositories due to the different conditions under which each dataset is generated. To better understand the relative noise-contributions of various factors in experimental-design, we assessed several Illumina and Affymetrix datasets for technical variation between replicate hybridisations of Universal Human Reference (UHRR) and individual or pooled breast-tumour RNA. A varying degree of systematic noise was observed in each of the datasets, however in all cases the relative amount of variation between standard control RNA replicates was found to be greatest at earlier points in the sample-preparation workflow. For example, 40.6% of the total variation in reported expressions were attributed to replicate extractions, compared to 13.9% due to amplification/labelling and 10.8% between replicate hybridisations. Deliberate probe-wise batch-correction methods were effective in reducing the magnitude of this variation, although the level of improvement was dependent on the sources of noise included in the model. Systematic noise introduced at the chip, run, and experiment levels of a combined Illumina dataset were found to be highly dependent upon the experimental design. Both UHRR and pools of RNA, which were derived from the samples of interest, modelled technical variation well although the pools were significantly better correlated (4% average improvement) and better emulated the effects of systematic noise, over all probes, than the UHRRs. The effect of this noise was not uniform over all probes, with low GC-content probes found to be more vulnerable to batch variation than probes with a higher GC-content. The magnitude of systematic processing noise in a microarray experiment is variable across probes and experiments, however it is generally the case that procedures earlier in the sample-preparation workflow are liable to introduce the most noise. Careful experimental design is important to protect against noise, detailed meta-data should always be provided, and diagnostic procedures should be routinely performed prior to downstream analyses for the detection of bias in microarray studies.

Relative impact of key sources of systematic noise in Affymetrix and Illumina gene-expression microarray experiments

PubMed Central

2011-01-01

Background Systematic processing noise, which includes batch effects, is very common in microarray experiments but is often ignored despite its potential to confound or compromise experimental results. Compromised results are most likely when re-analysing or integrating datasets from public repositories due to the different conditions under which each dataset is generated. To better understand the relative noise-contributions of various factors in experimental-design, we assessed several Illumina and Affymetrix datasets for technical variation between replicate hybridisations of Universal Human Reference (UHRR) and individual or pooled breast-tumour RNA. Results A varying degree of systematic noise was observed in each of the datasets, however in all cases the relative amount of variation between standard control RNA replicates was found to be greatest at earlier points in the sample-preparation workflow. For example, 40.6% of the total variation in reported expressions were attributed to replicate extractions, compared to 13.9% due to amplification/labelling and 10.8% between replicate hybridisations. Deliberate probe-wise batch-correction methods were effective in reducing the magnitude of this variation, although the level of improvement was dependent on the sources of noise included in the model. Systematic noise introduced at the chip, run, and experiment levels of a combined Illumina dataset were found to be highly dependant upon the experimental design. Both UHRR and pools of RNA, which were derived from the samples of interest, modelled technical variation well although the pools were significantly better correlated (4% average improvement) and better emulated the effects of systematic noise, over all probes, than the UHRRs. The effect of this noise was not uniform over all probes, with low GC-content probes found to be more vulnerable to batch variation than probes with a higher GC-content. Conclusions The magnitude of systematic processing noise in a microarray experiment is variable across probes and experiments, however it is generally the case that procedures earlier in the sample-preparation workflow are liable to introduce the most noise. Careful experimental design is important to protect against noise, detailed meta-data should always be provided, and diagnostic procedures should be routinely performed prior to downstream analyses for the detection of bias in microarray studies. PMID:22133085

The effect of dryer load on freeze drying process design.

PubMed

Patel, Sajal M; Jameel, Feroz; Pikal, Michael J

2010-10-01

Freeze-drying using a partial load is a common occurrence during the early manufacturing stages when insufficient amounts of active pharmaceutical ingredient (API) are available. In such cases, the immediate production needs are met by performing lyophilization with less than a full freeze dryer load. However, it is not obvious at what fractional load significant deviations from full load behavior begin. The objective of this research was to systematically study the effects of variation in product load on freeze drying behavior in laboratory, pilot and clinical scale freeze-dryers. Experiments were conducted with 5% mannitol (high heat and mass flux) and 5% sucrose (low heat and mass flux) at different product loads (100%, 50%, 10%, and 2%). Product temperature was measured in edge as well as center vials with thermocouples. Specific surface area (SSA) was measured by BET gas adsorption analysis and residual moisture was measured by Karl Fischer. In the lab scale freeze-dryer, the molar flux of inert gas was determined by direct flow measurement using a flowmeter and the molar flux of water vapor was determined by manometric temperature measurement (MTM) and tunable diode laser absorption spectroscopy (TDLAS) techniques. Comparative pressure measurement (capacitance manometer vs. Pirani) was used to determine primary drying time. For both 5% mannitol and 5% sucrose, primary drying time decreases and product temperature increases as the load on the shelves decreases. No systematic variation was observed in residual moisture and vapor composition as load decreased. Further, SSA data suggests that there are no significant freezing differences under different load conditions. Independent of dryer scale, among all the effects, variation in radiation heat transfer from the chamber walls to the product seems to be the dominant effect resulting in shorter primary drying time as the load on the shelf decreases (i.e., the fraction of edge vials increases).

Systematic documentation and analysis of human genetic variation in hemoglobinopathies using the microattribution approach.

PubMed

Giardine, Belinda; Borg, Joseph; Higgs, Douglas R; Peterson, Kenneth R; Philipsen, Sjaak; Maglott, Donna; Singleton, Belinda K; Anstee, David J; Basak, A Nazli; Clark, Barnaby; Costa, Flavia C; Faustino, Paula; Fedosyuk, Halyna; Felice, Alex E; Francina, Alain; Galanello, Renzo; Gallivan, Monica V E; Georgitsi, Marianthi; Gibbons, Richard J; Giordano, Piero C; Harteveld, Cornelis L; Hoyer, James D; Jarvis, Martin; Joly, Philippe; Kanavakis, Emmanuel; Kollia, Panagoula; Menzel, Stephan; Miller, Webb; Moradkhani, Kamran; Old, John; Papachatzopoulou, Adamantia; Papadakis, Manoussos N; Papadopoulos, Petros; Pavlovic, Sonja; Perseu, Lucia; Radmilovic, Milena; Riemer, Cathy; Satta, Stefania; Schrijver, Iris; Stojiljkovic, Maja; Thein, Swee Lay; Traeger-Synodinos, Jan; Tully, Ray; Wada, Takahito; Waye, John S; Wiemann, Claudia; Zukic, Branka; Chui, David H K; Wajcman, Henri; Hardison, Ross C; Patrinos, George P

2011-03-20

We developed a series of interrelated locus-specific databases to store all published and unpublished genetic variation related to hemoglobinopathies and thalassemia and implemented microattribution to encourage submission of unpublished observations of genetic variation to these public repositories. A total of 1,941 unique genetic variants in 37 genes, encoding globins and other erythroid proteins, are currently documented in these databases, with reciprocal attribution of microcitations to data contributors. Our project provides the first example of implementing microattribution to incentivise submission of all known genetic variation in a defined system. It has demonstrably increased the reporting of human variants, leading to a comprehensive online resource for systematically describing human genetic variation in the globin genes and other genes contributing to hemoglobinopathies and thalassemias. The principles established here will serve as a model for other systems and for the analysis of other common and/or complex human genetic diseases.

Social support and glycemic control in type 2 diabetes: a systematic review of observational studies.

PubMed

Stopford, Rosanna; Winkley, Kirsty; Ismail, Khalida

2013-12-01

We aim to systematically review observational studies examining the association between social support and glycemic control in adults with type 2 diabetes. We searched MEDLINE, PsycINFO, EMBASE, Scopus, Web of Science and Sociological Abstracts to July 2012 for observational studies investigating the association between structural or functional aspects of social support (social networks, community ties, marital status, family support, perceived, actual, emotional or instrumental social support) and glycemic control (HbA1c). From electronic and reference searches, 29 studies were eligible. Twenty different assessments of social support were used. Family support and composite measures of support were most frequently associated with reduced HbA1c. There was no evidence for a beneficial effect of other support measures on HbA1c. We found marked variation in population, setting, measurement of social support and definition of outcome, limiting the methodological validity of research. Social support may be important in the management of type 2 diabetes, the need for consensus and standardization of measures is highlighted. The presence of informal support should be explored in routine diabetes care. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Cohesive properties of (Cu,Ni)-(In,Sn) intermetallics: Database, electron-density correlations and interpretation of bonding trends

NASA Astrophysics Data System (ADS)

Ramos, S. B.; González Lemus, N. V.; Cabeza, G. F.; Fernández Guillermet, A.

2016-06-01

This paper presents a systematic and comparative study of the composition and volume dependence of the cohesive properties for a large group of Me-X intermetallic phases (IPs) with Me=Cu,Ni and X=In,Sn, which are of interest in relation with the design of lead-free soldering (LFS) alloys. The work relies upon a database with total-energy versus volume information developed by using projected augmented waves (PAW) calculations. In previous papers by the current authors it was shown that these results account satisfactorily for the direct and indirect experimental data available. In the present work, the database is further expanded to investigate the composition dependence of the volume (V0), and the composition and volume dependence of the bulk modulus (B0) and cohesive energy (Ecoh). On these bases, an analysis is performed of the systematic effects of replacing Cu by Ni in several Me-X phases (Me=Cu,Ni and X=In,Sn) reported as stable and metastable, as well as various hypothetical compounds involved in the thermodynamic modeling of IPs using the Compound-Energy Formalism. Moreover, it is shown that the cohesion-related quantities (B0/V0)½ and (Ecoh½/V0) can be correlated with a parameter expressing the number of valence electrons per unit volume. These findings are compared in detail with related relations involving the Miedema empirical electron density at the boundary of the Wigner-Seitz cell. In view of the co-variation of the cohesive properties, Ecoh is selected as a key property and its composition and structure dependence is examined in terms of a theoretical view of the bonding which involves the hybridization of the d-states of Cu or Ni with the s and p-states of In or Sn, for this class of compounds. In particular, a comparative analysis is performed of the DOS of various representative, iso-structural Me-X compounds. Various effects of relevance to understand the consequences of replacing Cu by Ni in LFS alloys are highlighted and explained microscopically for the first time.

Scalable Super-Resolution Synthesis of Core-Vest Composites Assisted by Surface Plasmons.

PubMed

Montazeri, A O; Kim, Y; Fang, Y S; Soheilinia, N; Zaghi, G; Clark, J K; Maboudian, R; Kherani, N P; Carraro, C

2018-02-15

The behavior of composite nanostructures depends on both size and elemental composition. Accordingly, concurrent control of size, shape, and composition of nanoparticles is key to tuning their functionality. In typical core-shell nanoparticles, the high degree of symmetry during shell formation results in fully encapsulated cores with severed access to the surroundings. We commingle light parameters (wavelength, intensity, and pulse duration) with the physical properties of nanoparticles (size, shape, and composition) to form hitherto unrealized core-vest composite nanostructures (CVNs). Unlike typical core-shells, the plasmonic core of the resulting CVNs selectively maintains physical access to its surrounding. Tunable variations in local temperature profiles ≳50 °C are plasmonically induced over starburst-shaped nanoparticles as small as 50-100 nm. These temperature variations result in CVNs where the shell coverage mirrors the temperature variations. The precision thus offered individually tailors access pathways of the core and the shell.

Evidences of the inheritance of turpentine composition in slash pine

Treesearch

A.E. Squillace; Gordon S. Fisher

1966-01-01

Within-species variation in turpentine composition has promise of great utility in pine genetics. Most of the early work on turpentine composition dealt with species differences, and the utility of such variation in the taxonomy of pines is well known (Mirov 1961). With the development of gas chromatographic techniques, intensive study of individual tree differences...

Interaction of Theory and Practice to Assess External Validity.

PubMed

Leviton, Laura C; Trujillo, Mathew D

2016-01-18

Variations in local context bedevil the assessment of external validity: the ability to generalize about effects of treatments. For evaluation, the challenges of assessing external validity are intimately tied to the translation and spread of evidence-based interventions. This makes external validity a question for decision makers, who need to determine whether to endorse, fund, or adopt interventions that were found to be effective and how to ensure high quality once they spread. To present the rationale for using theory to assess external validity and the value of more systematic interaction of theory and practice. We review advances in external validity, program theory, practitioner expertise, and local adaptation. Examples are provided for program theory, its adaptation to diverse contexts, and generalizing to contexts that have not yet been studied. The often critical role of practitioner experience is illustrated in these examples. Work is described that the Robert Wood Johnson Foundation is supporting to study treatment variation and context more systematically. Researchers and developers generally see a limited range of contexts in which the intervention is implemented. Individual practitioners see a different and often a wider range of contexts, albeit not a systematic sample. Organized and taken together, however, practitioner experiences can inform external validity by challenging the developers and researchers to consider a wider range of contexts. Researchers have developed a variety of ways to adapt interventions in light of such challenges. In systematic programs of inquiry, as opposed to individual studies, the problems of context can be better addressed. Evaluators have advocated an interaction of theory and practice for many years, but the process can be made more systematic and useful. Systematic interaction can set priorities for assessment of external validity by examining the prevalence and importance of context features and treatment variations. Practitioner interaction with researchers and developers can assist in sharpening program theory, reducing uncertainty about treatment variations that are consistent or inconsistent with the theory, inductively ruling out the ones that are harmful or irrelevant, and helping set priorities for more rigorous study of context and treatment variation. © The Author(s) 2016.

The composition of heavy ions in solar energetic particle events

NASA Technical Reports Server (NTRS)

Fan, C. Y.; Gloeckler, G.; Hovestadt, D.

1983-01-01

Recent advances in determining the elemental, charge state, and isotopic composition of or approximate to 1 to or approximate to 20 MeV per nucleon ions in solar energetic particle (SEP) events and outline our current understanding of the nature of solar and interplanetary processes which may explain the observations. Average values of relative abundances measured in a large number of SEP events were found to be roughly energy independent in the approx. 1 to approx. 20 MeV per nucleon range, and showed a systematic deviation from photospheric abundances which seems to be organized in terms of the first ionization potential of the ion. Direct measurements of the charge states of SEPs revealed the surprisingly common presence of energetic He(+) along with heavy ion with typically coronal ionization states. High resolution measurements of isotopic abundance ratios in a small number of SEP events showed these to be consistent with the universal composition except for the puzzling overabundance of the SEP(22)Ne/(20)Ne relative to this isotopes ratio in the solar wind. The broad spectrum of observed elemental abundance variations, which in their extreme result in composition anomalies characteristic of (3)He rich, heavy ion rich and carbon poor SEP events, along with direct measurements of the ionization states of SEPs provided essential information on the physical characteristics of, and conditions in the source regions, as well as important constraints to possible models for SEP production.

Correlation of Fiber Composite Tensile Strength with the Ultrasonic Stress Wave Factor

NASA Technical Reports Server (NTRS)

Vary, A.; Lark, R. F.

1978-01-01

An ultrasonic-acoustic technique was used to indicate the strength variations of tensile specimens of a graphite-epoxy composite. A stress wave factor was determined and its value was found to depend on variations of the fiber-resin bonding as well as fiber orientation. The fiber orientations studied were 0 deg (longitudinal), 10 deg (off-axis), 90 deg (transverse), 0 deg + or - 45 deg/0 deg symmetrical, and + or - 45 deg] symmetrical. The stress wave factor can indicate variations of the tensile and shear strengths of composite materials. The stress wave factor was also found to be sensitive to strength variations associated with microporosity and differences in fiber-resin ratio.

Combinatorial Strategies for the Development of Bulk Metallic Glasses

NASA Astrophysics Data System (ADS)

Ding, Shiyan

The systematic identification of multi-component alloys out of the vast composition space is still a daunting task, especially in the development of bulk metallic glasses that are typically based on three or more elements. In order to address this challenge, combinatorial approaches have been proposed. However, previous attempts have not successfully coupled the synthesis of combinatorial libraries with high-throughput characterization methods. The goal of my dissertation is to develop efficient high-throughput characterization methods, optimized to identify glass formers systematically. Here, two innovative approaches have been invented. One is to measure the nucleation temperature in parallel for up-to 800 compositions. The composition with the lowest nucleation temperature has a reasonable agreement with the best-known glass forming composition. In addition, the thermoplastic formability of a metallic glass forming system is determined through blow molding a compositional library. Our results reveal that the composition with the largest thermoplastic deformation correlates well with the best-known formability composition. I have demonstrated both methods as powerful tools to develop new bulk metallic glasses.

Processing and mechanical properties of metal-ceramic composites with controlled microstructure formed by reactive metal penetration

NASA Astrophysics Data System (ADS)

Ellerby, Donald Thomas

1999-12-01

Compared to monolithic ceramics, metal-reinforced ceramic composites offer the potential for improved toughness and reliability in ceramic materials. As such, there is significant scientific and commercial interest in the microstructure and properties of metal-ceramic composites. Considerable work has been conducted on modeling the toughening behavior of metal reinforcements in ceramics; however, there has been limited application and testing of these concepts on real systems. Composites formed by newly developed reactive processes now offer the flexibility to systematically control metal-ceramic composite microstructure, and to test some of the property models that have been proposed for these materials. In this work, the effects of metal-ceramic composite microstructure on resistance curve (R-curve) behavior, strength, and reliability were systematically investigated. Al/Al2O3 composites were formed by reactive metal penetration (RMP) of aluminum metal into aluminosilicate ceramic preforms. Processing techniques were developed to control the metal content, metal composition, and metal ligament size in the resultant composite microstructure. Quantitative stereology and microscopy were used to characterize the composite microstructures, and then the influence of microstructure on strength, toughness, R-curve behavior, and reliability, was investigated. To identify the strength limiting flaws in the composite microstructure, fractography was used to determine the failure origins. Additionally, the crack bridging tractions produced by the metal ligaments in metal-ceramic composites formed by the RMP process were modeled. Due to relatively large flaws and low bridging stresses in RMP composites, no dependence of reliability on R-curve behavior was observed. The inherent flaws formed during reactive processing appear to limit the strength and reliability of composites formed by the RMP process. This investigation has established a clear relationship between processing, microstructure, and properties in metal-ceramic composites formed by the RMP process. RMP composite properties are determined by the metal-ceramic composite microstructure (e.g., metal content and ligament size), which can be systematically varied by processing. Furthermore, relative to the ceramic preforms used to make the composites, metal-ceramic composites formed by RMP generally have improved properties and combinations of properties that make them more desirable for advanced engineering applications.

Systematic, Cross-Cortex Variation in Neuron Numbers in Rodents and Primates

PubMed Central

Charvet, Christine J.; Cahalane, Diarmuid J.; Finlay, Barbara L.

2015-01-01

Uniformity, local variability, and systematic variation in neuron numbers per unit of cortical surface area across species and cortical areas have been claimed to characterize the isocortex. Resolving these claims has been difficult, because species, techniques, and cortical areas vary across studies. We present a stereological assessment of neuron numbers in layers II–IV and V–VI per unit of cortical surface area across the isocortex in rodents (hamster, Mesocricetus auratus; agouti, Dasyprocta azarae; paca, Cuniculus paca) and primates (owl monkey, Aotus trivigratus; tamarin, Saguinus midas; capuchin, Cebus apella); these chosen to vary systematically in cortical size. The contributions of species, cortical areas, and techniques (stereology, “isotropic fractionator”) to neuron estimates were assessed. Neurons per unit of cortical surface area increase across the rostro-caudal (RC) axis in primates (varying by a factor of 1.64–2.13 across the rostral and caudal poles) but less in rodents (varying by a factor of 1.15–1.54). Layer II–IV neurons account for most of this variation. When integrated into the context of species variation, and this RC gradient in neuron numbers, conflicts between studies can be accounted for. The RC variation in isocortical neurons in adulthood mirrors the gradients in neurogenesis duration in development. PMID:23960207

Helical tomotherapy setup variations in canine nasal tumor patients immobilized with a bite block.

PubMed

Kubicek, Lyndsay N; Seo, Songwon; Chappell, Richard J; Jeraj, Robert; Forrest, Lisa J

2012-01-01

The purpose of our study was to compare setup variation in four degrees of freedom (vertical, longitudinal, lateral, and roll) between canine nasal tumor patients immobilized with a mattress and bite block, versus a mattress alone. Our secondary aim was to define a clinical target volume (CTV) to planning target volume (PTV) expansion margin based on our mean systematic error values associated with nasal tumor patients immobilized by a mattress and bite block. We evaluated six parameters for setup corrections: systematic error, random error, patient-patient variation in systematic errors, the magnitude of patient-specific random errors (root mean square [RMS]), distance error, and the variation of setup corrections from zero shift. The variations in all parameters were statistically smaller in the group immobilized by a mattress and bite block. The mean setup corrections in the mattress and bite block group ranged from 0.91 mm to 1.59 mm for the translational errors and 0.5°. Although most veterinary radiation facilities do not have access to Image-guided radiotherapy (IGRT), we identified a need for more rigid fixation, established the value of adding IGRT to veterinary radiation therapy, and define the CTV-PTV setup error margin for canine nasal tumor patients immobilized in a mattress and bite block. © 2012 Veterinary Radiology & Ultrasound.

Rear-arc vs. arc-front volcanoes in the Katmai reach of the Alaska Peninsula: A critical appraisal of across-arc compositional variation

USGS Publications Warehouse

Hildreth, W.; Fierstein, J.; Siems, D.F.; Budahn, J.R.; Ruiz, J.

2004-01-01

Physical and compositional data and K-Ar ages are reported for 14 rear-arc volcanoes that lic 11-22 km behind the narrowly linear volcanic front defined by the Mount Katmai-to-Devils Desk chain on the Alaska Peninsula. One is a 30-km3 stratocone (Mount Griggs; 51-63% SiO2) active intermittently from 292 ka to Holocene. The others are monogenetic cones, domes, lava flows, plugs, and maars, of which 12 were previously unnamed and unstudied; they include seven basalts (48-52% SiO2), four mafic andesites (53-55% SiO2), and three andesite-dacite units. Six erupted in the interval 500-88 ka, one historically in 1977, and five in the interval 3-2 Ma. No migration of the volcanic front is discernible since the late Miocene, so even the older units erupted well behind the front. Discussion explores the significance of the volcanic front and the processes that influence compositional overlaps and differences among mafic products of the rear-arc volcanoes and of the several arc-front edifices nearby. The latter have together erupted a magma volume of about 200 km3, at least four times that of all rear-arc products combined. Correlation of Sr-isotope ratios with indices of fractionation indicates crustal contributions in volcanic-front magmas (0.7033-0.7038), but lack of such trends among the rear-arc units (0.70298-0.70356) suggests weaker and less systematic crustal influence. Slab contributions and mantle partial-melt fractions both appear to decline behind the front, but neither trend is crisp and unambiguous. No intraplate mantle contribution is recognized nor is any systematic across-arc difference in intrinsic mantle-wedge source fertility discerned. Both rear-arc and arc-front basalts apparently issued from fluxing of typically fertile NMORB-source mantle beneath the Peninsular terrane, which docked here in the Mesozoic. ?? Springer-Verlag 2004.

Effects of dietary protein intake on body composition changes after weight loss in older adults: a systematic review and meta-analysis

PubMed Central

Kim, Jung Eun; O’Connor, Lauren E.; Sands, Laura P.; Slebodnik, Mary B.

2016-01-01

Context: The impact of dietary protein on body composition changes after older adults purposefully lose weight requires systematic evaluation. Objective: This systematic review and meta-analysis assessed the effects of protein intake (<25% vs ≥25% of energy intake or 1.0 g/kg/d) on energy restriction–induced changes in body mass, lean mass, and fat mass in adults older than 50 years. Data Sources: PubMed, Cochrane, Scopus, and Google Scholar were searched using the keywords “dietary proteins,” “body composition,” “skeletal muscle,” and “muscle strength.” Study Selection: Two researchers independently screened 1542 abstracts. Data Extraction: Information was extracted from 24 articles. Data Synthesis: Twenty randomized control trials met the inclusion criteria. Conclusion: Older adults retained more lean mass and lost more fat mass during weight loss when consuming higher protein diets. PMID:26883880

Rapid Mantle Source Variations During the Latest Episode of Kilauea's Prolonged Pu'u O'o Eruption, Hawaii

NASA Astrophysics Data System (ADS)

Marske, J. P.; Garcia, M. O.; Pietruszka, A. J.; Norman, M. D.; Rhodes, J. M.

2006-12-01

Nearly 24 years of continuous geochemical monitoring of lavas from the current Pu'u O'o eruption allow us to probe the mantle processes beneath Kilauea Volcano in unparalleled detail. Here we present new measurements Pb, Sr, and Nd isotope ratios and major- and trace-element abundances for lavas from episode 55 (1997-2006), which marks the longest and most voluminous interval of this eruption. Pu'u O'o lavas erupted since 1985 display systematic decreases in their TiO2, K2O, P2O5 and CaO abundances (normalized to 10 wt. % MgO to correct for olivine control) due to changes in the parental magma composition. Incompatible element ratios (e.g., Ba/Nb and La/Y) also show overall temporal decreases. Earlier erupted Pu'u O'o lavas displayed the most significant decrease in incompatible element ratios with near constant SiO2 contents, and a gradual increase in 87Sr/86Sr ratios. However, episode 55 lavas record significant increases in MgO- normalized SiO2 contents and 87Sr/86Sr with nearly constant (e.g. Ba/Nb) or a slightly reversed (e.g., TiO2 and K2O) trends in incompatible element ratios and abundances. There is little variation of 206Pb/204Pb ratios in lavas (18.38-18.43) erupted since 1985. Neither a single mantle source composition nor a change in partial melting conditions alone can explain these observations. Based on the isotopic and chemical variability, we conclude that early Pu'u O'o lavas originated from two distinct mantle source components: (1) a long-term depleted component (with relatively low 87Sr/86Sr ratios) that originated within the deep source of the Hawaiian plume that characterizes the earlier part of the eruption (1985-1992), and (2) a recently depleted component (i.e. a component that was recently depleted by prior melting) with low abundances of incompatible elements became increasingly important from 1992-1997. More recently, Pu'u O'o has tapped greater proportions of a new (3) long-term less depleted component (with higher 87Sr/86Sr ratios than observed from 1985-1992) that originated within the deep source region of the plume. This third component lies within typical Pb, Sr and Nd isotopic space for Kilauea, but represents a new source composition for the Pu'u O'o eruption. The systematic geochemical evolution of Pu'u O'o lavas reflects changes in the proportions of the mantle source components tapped throughout the eruption. The rapid isotope variations (on a time scale of years) in the most recent lavas suggest the mantle source components are heterogeneous on an extremely small scale, relative to the size of Kilauea's melting region.

Adsorption Effectivity Test of Andisols Clay-Zeolite (ACZ) Composite as Chromium Hexavalent (Cr(VI)) Ion Adsorbent

NASA Astrophysics Data System (ADS)

Pranoto; Masykur, A.; Nugroho, Y. A.

2018-03-01

Adsorption of chromium hexavalent (Cr(VI)) ion in aqueous solution was investigated. This research was purposed to study the influence of the composition of ACZ, temperature activation, and contact time against adsorption capacity of Cr(VI) ion in aqueous solution. Determination of adsorption effectivity using several parameter such as composition variation of ACZ, contact time, pH, activation temperature, and concentration. In this research, andisol clay and zeolite has been activated with NaOH 3 M and 1 M, respectively. Temperature variation used 100, 200, and 400°C. While composition variation ACZ used 0:100, 25:75, 50:50, 75:25, 100:0. The pH variation was used 2 – 6 and concentration variation using 2, 4, 6, 8, 10, and 12 ppm. Characterization in this research used such as UV-Vis, Surface Area Analyzer (SAA) and Acidity Analysis. Result of this research is known that optimum composition of ACZ was 50:50 with calcination temperature 100°C. Optimum adsorption of Cr(VI) at pH 4 with removal percentage 76.10 % with initial concentration 2 ppm and adsorption capacity is 0.16 mg/g. Adsorption isotherm following freundlich isotherm with value Kf = 0.17 mg/g and value n is 0.963. Based on results, ACZ composite can be used as Cr(VI) ion adsorbents in aqueous solutions.

Regional-scale drivers of forest structure and function in northwestern Amazonia.

PubMed

Higgins, Mark A; Asner, Gregory P; Anderson, Christopher B; Martin, Roberta E; Knapp, David E; Tupayachi, Raul; Perez, Eneas; Elespuru, Nydia; Alonso, Alfonso

2015-01-01

Field studies in Amazonia have found a relationship at continental scales between soil fertility and broad trends in forest structure and function. Little is known at regional scales, however, about how discrete patterns in forest structure or functional attributes map onto underlying edaphic or geological patterns. We collected airborne LiDAR (Light Detection and Ranging) data and VSWIR (Visible to Shortwave Infrared) imaging spectroscopy measurements over 600 km2 of northwestern Amazonian lowland forests. We also established 83 inventories of plant species composition and soil properties, distributed between two widespread geological formations. Using these data, we mapped forest structure and canopy reflectance, and compared them to patterns in plant species composition, soils, and underlying geology. We found that variations in soils and species composition explained up to 70% of variation in canopy height, and corresponded to profound changes in forest vertical profiles. We further found that soils and plant species composition explained more than 90% of the variation in canopy reflectance as measured by imaging spectroscopy, indicating edaphic and compositional control of canopy chemical properties. We last found that soils explained between 30% and 70% of the variation in gap frequency in these forests, depending on the height threshold used to define gaps. Our findings indicate that a relatively small number of edaphic and compositional variables, corresponding to underlying geology, may be responsible for variations in canopy structure and chemistry over large expanses of Amazonian forest.

Synthesis, characterization, and ion-exchange properties of colloidal zeolite nanocrystals

NASA Astrophysics Data System (ADS)

Jawor, Anna; Jeong, Byeong-Heon; Hoek, Eric M. V.

2009-10-01

Here, we present physical-chemical properties of Linde type A (LTA) zeolite crystals synthesized via conventional hydrothermal and microwave heating methods. Both heating methods produced LTA crystals that were sub-micron in size, highly negatively charged, super-hydrophilic, and stable when dispersed in water. However, microwave heating produced relatively narrow crystal size distributions, required much shorter heating times, and did not significantly change composition, crystallinity, or surface chemistry. Moreover, microwave heating allowed systematic variation of crystal size by varying heating temperature and time during the crystallization reaction, thus producing a continuous gradient of crystal sizes ranging from about 90 to 300 nm. In ion-exchange studies, colloidal zeolites exhibited excellent sorption kinetics and capacity for divalent metal ions, suggesting their potential for use in water softening, scale inhibition, and scavenging of toxic metal ions from water.

Chromium isotope variations (δ53/52Cr) in mantle-derived sources and their weathering products: Implications for environmental studies and the evolution of δ53/52Cr in the Earth’s mantle over geologic time

NASA Astrophysics Data System (ADS)

Farkaš, Juraj; Chrastný, Vladislav; Novák, Martin; Čadkova, Eva; Pašava, Jan; Chakrabarti, Ramananda; Jacobsen, Stein B.; Ackerman, Lukáš; Bullen, Thomas D.

2013-12-01

Here we report chromium isotope compositions, expressed as δ53/52Cr in per mil (‰) relative to NIST 979, measured in selected Cr-rich minerals and rocks formed by the primary magmatic as well as the secondary metamorphic and weathering processes. The main objectives of this study were: (i) to further constrain the isotope composition of the Earth’s mantle Cr inventory and its possible variation during geological history, based on the analysis of globally distributed and stratigraphically constrained mantle-derived chromites; and (ii) to investigate the magnitude and systematics of Cr isotope fractionation during oxidative weathering and secondary alteration (i.e., hydration, serpentinization) of the magmatic Cr sources. Specifically, we analyzed δ53/52Cr in a set of globally distributed mantle-derived chromites (FeMgCr2O4, n = 30) collected from various locations in Europe, Asia, Africa and South America, and our results confirm that a chromite-hosted Earth’s mantle Cr inventory is uniform at -0.079 ± 0.129‰ (2SD), which we named here as a ‘canonical’ mantle δ53/52Cr signature. Furthermore our dataset of stratigraphically constrained chromites, whose crystallization ages cover most of the Earth’s geological history, indicate that the bulk Cr isotope composition of the chromite-hosted mantle inventory has remained uniform, within about ±0.100‰, since at least the Early Archean times (∼3500 million years ago, Ma). To investigate the systematics of Cr isotope fractionation associated with alteration processes we analyzed a number of secondary Cr-rich minerals and variably altered ultramafic rocks (i.e., serpentinized harzburgites, lherzolites) that revealed large positive δ53/52Cr anomalies that are systematically shifted to higher values with an increasing degree of alteration and serpentinization. The degree of aqueous alteration and serpentinization was quantified by the abundances of fluid-mobile (Rb, K) elements, and by the Loss On Ignition (LOI) parameter, which determines the amount of structurally bound water (OH/H2O) present in secondary hydrated minerals like serpentine. Overall, we observed that altered ultramafic rocks that yielded the highest LOI values, and the lowest amounts of fluid mobile elements, also yielded the heaviest δ53/52Cr signatures. Therefore, we conclude that secondary alteration (i.e., hydration, serpentinization) of ultramafic rocks in near-surface oxidative environments tend to shift the bulk Cr isotope composition of the weathered products to isotopically heavier values, pointing to a dynamic redox cycling of Cr in the Earth’s crustal and near-surface environments. Hence, if validated by future studies, this would suggest that Cr isotopes could be used to trace the recycling of altered oceanic lithosphere through subduction zones, and to detect the sources of dehydrated and previously serpentinized oceanic crust carrying ‘heavy’ δ53/52Cr signatures in island arc systems. Finally, the fact that the geogenic Cr sources may locally exhibit anomalous (non-canonical) δ53/52Cr signatures has also implications for environmental studies that use δ53/52Cr as a tracer to quantify the amount of the hexavalent Cr reduction in waters.

Major and trace element modeling of mid-ocean ridge mantle melting from the garnet to the plagioclase stability fields: Generating local and global compositional variability

NASA Astrophysics Data System (ADS)

Brown, S. M.; Behn, M. D.; Grove, T. L.

2017-12-01

We present results of a combined petrologic - geochemical (major and trace element) - geodynamical forward model for mantle melting and subsequent melt modification. The model advances Behn & Grove (2015), and is calibrated using experimental petrology. Our model allows for melting in the plagioclase, spinel, and garnet fields with a flexible retained melt fraction (from pure batch to pure fractional), tracks residual mantle composition, and includes melting with water, variable melt productivity, and mantle mode calculations. This approach is valuable for understanding oceanic crustal accretion, which involves mantle melting and melt modification by migration and aggregation. These igneous processes result in mid-ocean ridge basalts that vary in composition at the local (segment) and global scale. The important variables are geophysical and geochemical and include mantle composition, potential temperature, mantle flow, and spreading rate. Accordingly, our model allows us to systematically quantify the importance of each of these external variables. In addition to discriminating melt generation effects, we are able to discriminate the effects of different melt modification processes (inefficient pooling, melt-rock reaction, and fractional crystallization) in generating both local, segment-scale and global-scale compositional variability. We quantify the influence of a specific igneous process on the generation of oceanic crust as a function of variations in the external variables. We also find that it is unlikely that garnet lherzolite melting produces a signature in either major or trace element compositions formed from aggregated melts, because when melting does occur in the garnet field at high mantle temperature, it contributes a relatively small, uniform fraction (< 10%) of the pooled melt compositions at all spreading rates. Additionally, while increasing water content and/or temperature promote garnet melting, they also increase melt extent, pushing the pooled composition to lower Sm/Yb and higher Lu/Hf.

Macro- and Micronutrients of Human Milk Composition: Are They Related to Maternal Diet? A Comprehensive Systematic Review.

PubMed

Keikha, Mojtaba; Bahreynian, Maryam; Saleki, Mohammad; Kelishadi, Roya

2017-11-01

This study aims at systematically reviewing the observational and interventional studies on the association of maternal macro- and micronutrient intake with breast milk content. We systematically searched the Medline via PubMed, Scopus, and ISI Web of Knowledge till October 2016 with the following search strategy: ("human milk" OR "breast milk" OR "breast milk composition" OR "human breast milk composition" OR "composition breast milk" OR "mother milk" OR "human breast milk") AND ("maternal diet" OR "maternal nutrition"). We also searched Google scholar for increasing the sensitivity of our search. The search was not limited to title and abstract due to the possibility that the desired outcome might have been considered a secondary aim. We excluded conference papers, editorials, letters, commentary, short survey, and notes. The search was refined to English language, and we did not consider any time limitation. To increase the sensitivity and to select more studies, the reference list of the published studies was checked as well. This review included 59 observational and 43 interventional studies on maternal diet related to breast milk composition. Different studies determined the associations and effects of some maternal dietary intake of micro and macronutrients and its reflection in human milk. Maternal dietary intake, particularly fatty acids, and some micronutrients, including fat soluble vitamins, vitamin B 1 , and vitamin C, was related to their content in breast milk composition.

Genetic architecture of kernel composition in global sorghum germplasm.

PubMed

Rhodes, Davina H; Hoffmann, Leo; Rooney, William L; Herald, Thomas J; Bean, Scott; Boyles, Richard; Brenton, Zachary W; Kresovich, Stephen

2017-01-05

Sorghum [Sorghum bicolor (L.) Moench] is an important cereal crop for dryland areas in the United States and for small-holder farmers in Africa. Natural variation of sorghum grain composition (protein, fat, and starch) between accessions can be used for crop improvement, but the genetic controls are still unresolved. The goals of this study were to quantify natural variation of sorghum grain composition and to identify single-nucleotide polymorphisms (SNPs) associated with variation in grain composition concentrations. In this study, we quantified protein, fat, and starch in a global sorghum diversity panel using near-infrared spectroscopy (NIRS). Protein content ranged from 8.1 to 18.8%, fat content ranged from 1.0 to 4.3%, and starch content ranged from 61.7 to 71.1%. Durra and bicolor-durra sorghum from Ethiopia and India had the highest protein and fat and the lowest starch content, while kafir sorghum from USA, India, and South Africa had the lowest protein and the highest starch content. Genome-wide association studies (GWAS) identified quantitative trait loci (QTL) for sorghum protein, fat, and starch. Previously published RNAseq data was used to identify candidate genes within a GWAS QTL region. A putative alpha-amylase 3 gene, which has previously been shown to be associated with grain composition traits, was identified as a strong candidate for protein and fat variation. We identified promising sources of genetic material for manipulation of grain composition traits, and several loci and candidate genes that may control sorghum grain composition. This survey of grain composition in sorghum germplasm and identification of protein, fat, and starch QTL contributes to our understanding of the genetic basis of natural variation in sorghum grain nutritional traits.

A systematic review of medical practice variation in OECD countries.

PubMed

Corallo, Ashley N; Croxford, Ruth; Goodman, David C; Bryan, Elisabeth L; Srivastava, Divya; Stukel, Therese A

2014-01-01

Major variations in medical practice have been documented internationally. Variations raise questions about the quality, equity, and efficiency of resource allocation and use, and have important implications for health care and health policy. To perform a systematic review of the peer-reviewed literature on medical practice variations in OECD countries. We searched MEDLINE to find publications on medical practice variations in OECD countries published between 2000 and 2011. We present an overview of the characteristics of published studies as well as the magnitude of variations for select high impact conditions. A total of 836 studies were included. Consistent with the gray literature, there were large variations across regions, hospitals and physician practices for almost every condition and procedure studied. Many studies focused on high-impact conditions, but very few looked at the causes or outcomes of medical practice variations. While there were an overwhelming number of publications on medical practice variations the coverage was broad and not often based on a theoretical construct. Future studies should focus on conditions and procedures that are clinically important, policy relevant, resource intensive, and have high levels of public awareness. Further study of the causes and consequences of variations is important. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Comparable Wages, Inflation, and School Finance Equity

ERIC Educational Resources Information Center

Taylor, Lori L.

2006-01-01

A Comparable Wage Index (CWI) is an attractive mechanism for measuring geographic variations in the cost of education. A CWI measures uncontrollable variations in educator pay by observing systematic variations in the earnings of comparable workers who are not educators. Together, the 2000 census and the Occupational Employment Statistics survey…

Estimating Cross-Site Impact Variation in the Presence of Heteroscedasticity

ERIC Educational Resources Information Center

Bloom, Howard S.; Porter, Kristin E.; Weiss, Michael J.; Raudenbush, Stephen

2013-01-01

To date, evaluation research and policy analysis have focused mainly on average program impacts and paid little systematic attention to their variation. Recently, the growing number of multi-site randomized trials that are being planned and conducted make it increasingly feasible to study "cross-site" variation in impacts. Important…

Seasonal dripwater Mg/Ca and Sr/Ca variations driven by cave ventilation: Implications for and modeling of speleothem paleoclimate records

USGS Publications Warehouse

Wong, C.I.; Banner, J.L.; Musgrove, M.

2011-01-01

A 4-year study in a central Texas cave quantifies multiple mechanisms that control dripwater composition and how these mechanisms vary at different drip sites. We monitored cave-air compositions, in situ calcite growth, dripwater composition and drip rate every 4-6weeks. Three groups of drip sites are delineated (Groups 1-3) based on geochemical variations in dripwater composition. Quantitative modeling of mineral-solution reactions within the host carbonate rock and cave environments is used to identify mechanisms that can account for variations in dripwater compositions. The covariation of Mg/Ca (and Sr/Ca) and Sr isotopes is key in delineating whether Mg/Ca and Sr/Ca variations are dictated by water-rock interaction (i.e., calcite or dolomite recrystallization) or prior calcite precipitation (PCP). Group 1 dripwater compositions reflects a narrow range of the extent of water-rock interaction followed by varying amounts of prior calcite precipitation (PCP). Group 2 dripwater compositions are controlled by varying amounts of water-rock interaction with little to no PCP influence. Group 3 dripwater compositions are dictated by variable extents of both water-rock interaction and PCP. Group 1 drip sites show seasonal variations in dripwater Mg/Ca and Sr/Ca, whereas the other drip sites do not. In contrast to the findings of most previous dripwater Mg/Ca-Sr/Ca studies, these seasonal variations (at Group 1 drip sites) are independent of changes in water flux (i.e., rainfall and/or drip rate), and instead significantly correlate with changes in cave-air CO2 concentrations. These results are consistent with lower cave-air CO2, related to cool season ventilation of the cave atmosphere, enhancing calcite precipitation and leading to dripwater geochemical evolution via PCP. Group 1 dripwater Mg/Ca and Sr/Ca seasonality and evidence for PCP as a mechanism that can account for that seasonality, have two implications for many other regions where seasonal ventilation of caves is likely: (1) speleothem trace-element records may provide seasonal signals, and (2) such records may be biased toward recording climate conditions during the season when calcite is depositing. Additionally, we use our results to construct a forward model that illustrates the types of speleothem Mg/Ca and Sr/Ca variations that would result from varying controls on dripwater compositions. The model provides a basis for interpreting paleo-dripwater controls from high frequency Mg/Ca and Sr/Ca variations for speleothems from caves at which long term monitoring studies are not feasible. ?? 2011 Elsevier Ltd.

Effect of plasma spray processing variations on particle melting and splat spreading of hydroxylapatite and alumina

NASA Astrophysics Data System (ADS)

Yankee, S. J.; Pletka, B. J.

1993-09-01

Splats of hydroxylapatite (HA) and alumina were obtained via plasma spraying using systematically varied combinations of plasma velocity and temperature, which were achieved by altering the primary plasma gas flow rate and plasma gas composition. Particle size was also varied in the case of alumina. Splat spreading was quantified via computer- aided image analysis as a function of processing variations. A comparison of the predicted splat dimensions from a model developed by Madejski with experimental observations of HA and alumina splats was performed. The model tended to underestimate the HA splat sizes, suggesting that evaporation of smaller particles occurred under the chosen experimental conditions, and to overestimate the observed alumina splat dimensions. Based on this latter result and on the surface appearance of the substrates, incomplete melting appeared to take place in all but the smaller alumina particles. Analysis of the spreading data as a function of the processing variations indicated that the particle size as well as the plasma temperature and velocity influenced the extent of particle melting. Based on these data and other considerations, a physical model was developed that described the degree of particle melting in terms of material and processing parameters. The physical model correctly predicted the relative splat spreading behavior of HA and alumina, assuming that spreading was directly linked to the extent of particle melting.

Constraints on Vesta's elemental composition: Fast neutron measurements by Dawn's gamma ray and neutron detector

PubMed Central

Lawrence, David J; Peplowski, Patrick N; Prettyman, Thomas H; Feldman, William C; Bazell, David; Mittlefehldt, David W; Reedy, Robert C; Yamashita, Naoyuki

2013-01-01

Surface composition information from Vesta is reported using fast neutron data collected by the gamma ray and neutron detector on the Dawn spacecraft. After correcting for variations due to hydrogen, fast neutrons show a compositional dynamic range and spatial variability that is consistent with variations in average atomic mass from howardite, eucrite, and diogenite (HED) meteorites. These data provide additional compositional evidence that Vesta is the parent body to HED meteorites. A subset of fast neutron data having lower statistical precision show spatial variations that are consistent with a 400 ppm variability in hydrogen concentrations across Vesta and supports the idea that Vesta's hydrogen is due to long-term delivery of carbonaceous chondrite material. PMID:26074718

Variation, certainty, evidence, and change in dental education: employing evidence-based dentistry in dental education.

PubMed

Marinho, V C; Richards, D; Niederman, R

2001-05-01

Variation in health care, and more particularly in dental care, was recently chronicled in a Readers Digest investigative report. The conclusions of this report are consistent with sound scientific studies conducted in various areas of health care, including dental care, which demonstrate substantial variation in the care provided to patients. This variation in care parallels the certainty with which clinicians and faculty members often articulate strongly held, but very different opinions. Using a case-based dental scenario, we present systematic evidence-based methods for accessing dental health care information, evaluating this information for validity and importance, and using this information to make informed curricular and clinical decisions. We also discuss barriers inhibiting these systematic approaches to evidence-based clinical decision making and methods for effectively promoting behavior change in health care professionals.

Meeting critical gate linewidth control needs at the 65 nm node

NASA Astrophysics Data System (ADS)

Mahorowala, Arpan; Halle, Scott; Gabor, Allen; Chu, William; Barberet, Alexandra; Samuels, Donald; Abdo, Amr; Tsou, Len; Yan, Wendy; Iseda, Seiji; Patel, Kaushal; Dirahoui, Bachir; Nomura, Asuka; Ahsan, Ishtiaq; Azam, Faisal; Berg, Gary; Brendler, Andrew; Zimmerman, Jeffrey; Faure, Tom

2006-03-01

With the nominal gate length at the 65 nm node being only 35 nm, controlling the critical dimension (CD) in polysilicon to within a few nanometers is essential to achieve a competitive power-to-performance ratio. Gate linewidths must be controlled, not only at the chip level so that the chip performs as the circuit designers and device engineers had intended, but also at the wafer level so that more chips with the optimum power-to-performance ratio are manufactured. Achieving tight across-chip linewidth variation (ACLV) and chip mean variation (CMV) is possible only if the mask-making, lithography, and etching processes are all controlled to very tight specifications. This paper identifies the various ACLV and CMV components, describes their root causes, and discusses a methodology to quantify them. For example, the site-to-site ACLV component is divided into systematic and random sub-components. The systematic component of the variation is attributed in part to pattern density variation across the field, and variation in exposure dose across the slit. The paper demonstrates our team's success in achieving the tight gate CD tolerances required for 65 nm technology. Certain key challenges faced, and methods employed to overcome them are described. For instance, the use of dose-compensation strategies to correct the small but systematic CD variations measured across the wafer, is described. Finally, the impact of immersion lithography on both ACLV and CMV is briefly discussed.

Calibration of Herschel SPIRE FTS observations at different spectral resolutions

NASA Astrophysics Data System (ADS)

Marchili, N.; Hopwood, R.; Fulton, T.; Polehampton, E. T.; Valtchanov, I.; Zaretski, J.; Naylor, D. A.; Griffin, M. J.; Imhof, P.; Lim, T.; Lu, N.; Makiwa, G.; Pearson, C.; Spencer, L.

2017-01-01

The SPIRE Fourier Transform Spectrometer on-board the Herschel Space Observatory had two standard spectral resolution modes for science observations: high resolution (HR) and low resolution (LR), which could also be performed in sequence (H+LR). A comparison of the HR and LR resolution spectra taken in this sequential mode revealed a systematic discrepancy in the continuum level. Analysing the data at different stages during standard pipeline processing demonstrates that the telescope and instrument emission affect HR and H+LR observations in a systematically different way. The origin of this difference is found to lie in the variation of both the telescope and instrument response functions, while it is triggered by fast variation of the instrument temperatures. As it is not possible to trace the evolution of the response functions using housekeeping data from the instrument subsystems, the calibration cannot be corrected analytically. Therefore, an empirical correction for LR spectra has been developed, which removes the systematic noise introduced by the variation of the response functions.

Mantle source heterogeneity of the Early Jurassic basalt of eastern North America

NASA Astrophysics Data System (ADS)

Gregory Shellnutt, J.; Dostal, Jaroslav; Yeh, Meng-Wan

2018-04-01

One of the defining characteristics of the basaltic rocks from the Early Jurassic Eastern North America (ENA) sub-province of the Central Atlantic Magmatic Province (CAMP) is the systematic compositional variation from South to North. Moreover, the tectono-thermal regime of the CAMP is debated as it demonstrates geological and structural characteristics (size, radial dyke pattern) that are commonly associated with mantle plume-derived mafic continental large igneous provinces but is considered to be unrelated to a plume. Mantle potential temperature ( T P) estimates of the northern-most CAMP flood basalts (North Mountain basalt, Fundy Basin) indicate that they were likely produced under a thermal regime ( T P ≈ 1450 °C) that is closer to ambient mantle ( T P ≈ 1400 °C) conditions and are indistinguishable from other regions of the ENA sub-province ( T Psouth = 1320-1490 °C, T Pnorth = 1390-1480 °C). The regional mantle potential temperatures are consistent along the 3000-km-long ENA sub-province suggesting that the CAMP was unlikely to be generated by a mantle plume. Furthermore, the mantle potential temperature calculation using the rocks from the Northern Appalachians favors an Fe-rich mantle (FeOt = 8.6 wt %) source, whereas the rocks from the South Appalachians favor a less Fe-rich (FeOt = 8.3 wt %) source. The results indicate that the spatial-compositional variation of the ENA basaltic rocks is likely related to differing amounts of melting of mantle sources that reflect the uniqueness of their regional accreted terranes (Carolinia and West Avalonia) and their post-accretion, pre-rift structural histories.

Systematic pharmacogenomics analysis of a Malay whole genome: proof of concept for personalized medicine.

PubMed

Salleh, Mohd Zaki; Teh, Lay Kek; Lee, Lian Shien; Ismet, Rose Iszati; Patowary, Ashok; Joshi, Kandarp; Pasha, Ayesha; Ahmed, Azni Zain; Janor, Roziah Mohd; Hamzah, Ahmad Sazali; Adam, Aishah; Yusoff, Khalid; Hoh, Boon Peng; Hatta, Fazleen Haslinda Mohd; Ismail, Mohamad Izwan; Scaria, Vinod; Sivasubbu, Sridhar

2013-01-01

With a higher throughput and lower cost in sequencing, second generation sequencing technology has immense potential for translation into clinical practice and in the realization of pharmacogenomics based patient care. The systematic analysis of whole genome sequences to assess patient to patient variability in pharmacokinetics and pharmacodynamics responses towards drugs would be the next step in future medicine in line with the vision of personalizing medicine. Genomic DNA obtained from a 55 years old, self-declared healthy, anonymous male of Malay descent was sequenced. The subject's mother died of lung cancer and the father had a history of schizophrenia and deceased at the age of 65 years old. A systematic, intuitive computational workflow/pipeline integrating custom algorithm in tandem with large datasets of variant annotations and gene functions for genetic variations with pharmacogenomics impact was developed. A comprehensive pathway map of drug transport, metabolism and action was used as a template to map non-synonymous variations with potential functional consequences. Over 3 million known variations and 100,898 novel variations in the Malay genome were identified. Further in-depth pharmacogenetics analysis revealed a total of 607 unique variants in 563 proteins, with the eventual identification of 4 drug transport genes, 2 drug metabolizing enzyme genes and 33 target genes harboring deleterious SNVs involved in pharmacological pathways, which could have a potential role in clinical settings. The current study successfully unravels the potential of personal genome sequencing in understanding the functionally relevant variations with potential influence on drug transport, metabolism and differential therapeutic outcomes. These will be essential for realizing personalized medicine through the use of comprehensive computational pipeline for systematic data mining and analysis.

Vanadium isotope heterogeneity of the early solar system

NASA Astrophysics Data System (ADS)

Nielsen, S.; Auro, M. E. E.; Magna, T.; Davis, D. M.; Mezger, K.; Sarafian, A. R.

2017-12-01

Vanadium (V) has two isotopes with masses 50 and 51 that have 51V/50V ratio of 410. This ratio can be modified by production of 50V through cosmic irradiation, heterogeneous distribution of anomalous nucleosynthetic material and stable isotope fractionation. Due to the existence of only two V isotopes in nature, these latter processes cannot directly be distinguished from irradiation processes. Previous data has suggested that Earth is characterized by 51V/50V that is significantly different to that of meteorites. These data are difficult to reconcile with a singular process that caused the V isotope variation in the early Solar System. Here we present new V isotope data for a large range of meteorites in order to investigate the ultimate origin of V isotope variation in the early Solar System. We find limited and non-systematic 51V/50V variation of 0.3‰ for 25 martian meteorites (depleted/intermediate/enriched shergottites, nakhlites, and chassignite and orthopyroxenite ALH 84001), which suggests that igneous processes on Mars did not induce significant V isotope shifts. Our best estimate for V isotope composition of the bulk silicate Mars can thus be approximated by the mean value of the entire Martian meteorite suite. This value is significantly lighter ( 0.4‰) than that measured for pristine terrestrial rocks. In contrast, meteorites from the HED parent body reveal significant 51V/50V variation that may be linked to magmatic processes such as fractional crystallization of Vestan magma ocean. The two data sets illustrate that several processes are likely to explain the V isotope variation found in meteorites. We will also present new V isotope data for carbonaceous and ordinary chondrites and put them in the context of the values found for Earth, Mars and the HED parent body.

Demographic controls of aboveground forest biomass across North America.

PubMed

Vanderwel, Mark C; Zeng, Hongcheng; Caspersen, John P; Kunstler, Georges; Lichstein, Jeremy W

2016-04-01

Ecologists have limited understanding of how geographic variation in forest biomass arises from differences in growth and mortality at continental to global scales. Using forest inventories from across North America, we partitioned continental-scale variation in biomass growth and mortality rates of 49 tree species groups into (1) species-independent spatial effects and (2) inherent differences in demographic performance among species. Spatial factors that were separable from species composition explained 83% and 51% of the respective variation in growth and mortality. Moderate additional variation in mortality (26%) was attributable to differences in species composition. Age-dependent biomass models showed that variation in forest biomass can be explained primarily by spatial gradients in growth that were unrelated to species composition. Species-dependent patterns of mortality explained additional variation in biomass, with forests supporting less biomass when dominated by species that are highly susceptible to competition (e.g. Populus spp.) or to biotic disturbances (e.g. Abies balsamea). © 2016 John Wiley & Sons Ltd/CNRS.

Mg isotope systematics during magmatic processes: Inter-mineral fractionation in mafic to ultramafic Hawaiian xenoliths

NASA Astrophysics Data System (ADS)

Stracke, A.; Tipper, E. T.; Klemme, S.; Bizimis, M.

2018-04-01

Observed differences in Mg isotope ratios between bulk magmatic rocks are small, often on a sub per mill level. Inter-mineral differences in the 26Mg/24Mg ratio (expressed as δ26Mg) in plutonic rocks are on a similar scale, and have mostly been attributed to equilibrium isotope fractionation at magmatic temperatures. Here we report Mg isotope data on minerals in spinel peridotite and garnet pyroxenite xenoliths from the rejuvenated stage of volcanism on Oahu and Kauai, Hawaii. The new data are compared to literature data and to theoretical predictions to investigate the processes responsible for inter-mineral Mg isotope fractionation at magmatic temperatures. Theory predicts up to per mill level differences in δ26Mg between olivine and spinel at magmatic temperatures and a general decrease in Δ26Mgolivine-spinel (=δ26Mgolivine - δ26Mgspinel) with increasing temperature, but also with increasing Cr# in spinel. For peridotites with a simple petrogenetic history by melt depletion, where increasing depletion relates to increasing melting temperatures, Δ26Mgolivine-spinel should thus systematically decrease with increasing Cr# in spinel. However, most natural peridotites, including the Hawaiian spinel peridotites investigated in this study, are overprinted by variable extents of melt-rock reaction, which disturb the systematic primary temperature and compositionally related olivine-spinel Mg isotope systematics. Diffusion, subsolidus re-equilibration, or surface alteration may further affect the observed olivine-spinel Mg isotope fractionation in peridotites, making Δ26Mgolivine-spinel in peridotites a difficult-to-apply geothermometer. The available Mg isotope data on clinopyroxene and garnet suggest that this mineral pair is a more promising geothermometer, but its application is restricted to garnet-bearing igneous (garnet pyroxenites) and metamorphic rocks (eclogites). Although the observed δ26Mg variation is on a sub per mill range in bulk magmatic rocks, the clearly resolvable inter-mineral Mg isotope differences imply that crystallization or preferential melting of isotopically distinct minerals such garnet, spinel, and clinopyroxene should cause Mg isotope fractionation between bulk melt and residue. Calculated Mg isotope variations during partial mantle melting indeed predict differences between melt and residue, but these are analytically resolvable only for melting of mafic lithologies, that is, garnet pyroxenites. Contributions from garnet pyroxenite melts may thus account for some of the isotopically light δ26Mg observed in ocean island basalts and trace lithological mantle heterogeneity. Consequently, applications for high-temperature Mg isotope fractionations are promising and diverse, and recent advances in analytical precision may allow the full petrogenetic potential inherent in the sub per mill variations in δ26Mg in magmatic rocks to be exploited.

Climate and Edaphic Controls on Humid Tropical Forest Tree Height

NASA Astrophysics Data System (ADS)

Yang, Y.; Saatchi, S. S.; Xu, L.

2014-12-01

Uncertainty in the magnitude and spatial variations of forest carbon density in tropical regions is due to under sampling of forest structure from inventory plots and the lack of regional allometry to estimate the carbon density from structure. Here we quantify the variation of tropical forest structure by using more than 2.5 million measurements of canopy height from systematic sampling of Geoscience Laser Altimeter System (GLAS) satellite observations between 2004 to 2008 and examine the climate and edaphic variables influencing the variations. We used top canopy height of GLAS footprints (~ 0.25 ha) to grid the statistical mean and 90 percentile of samples at 0.5 degrees to capture the regional variability of large trees in tropics. GLAS heights were also aggregated based on a stratification of tropical regions using soil, elevation, and forest types. Both approaches provided consistent patterns of statistically dominant large trees and the least heterogeneity, both as strong drivers of distribution of high biomass forests. Statistical models accounting for spatial autocorrelation suggest that climate, soil and spatial features together can explain more than 60% of the variations in observed tree height information, while climate-only variables explains about one third of the first-order changes in tree height. Soil basics, including physical compositions such as clay and sand contents, chemical properties such as PH values and cation-exchange capacity, as well as biological variables such as organic matters, all present independent but statistically significant relationships to tree height variations. The results confirm other landscape and regional studies that soil fertility, geology and climate may jointly control a majority of the regional variations of forest structure in pan-tropics and influencing both biomass stocks and dynamics. Consequently, other factors such as biotic and disturbance regimes, not included in this study, may have less influence on regional variations but strongly mediate landscape and small-scale forest structure and dynamics.

Structure, strain, and composition profiling of InAs/GaAs(211)B quantum dot superlattices

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

Florini, N.; Dimitrakopulos, G. P.; Kioseoglou, J.

2016-01-21

The morphology, nanostructure, and strain properties of InAs quantum dots (QDs) grown on GaAs(211)B, uncapped or buried, are explored by transmission electron microscopy and related quantitative techniques. Besides the built-in piezoelectric field, other differences of (211) growth compared to (100)-oriented growth are discussed in terms of the (211) surface non-singularity, leading to anisotropic shape of the QDs and local chemical inhomogeneity of the wetting layer. The shape of the uncapped QDs was precisely defined as truncated pyramidal, elongated along the 〈111〉 direction, and bounded by the (110), (100), and (213) facets. Local strain measurements showed that large surface QDs weremore » almost unstrained due to plastic relaxation, exhibiting small residual elastic strain at the interface that gradually diminished toward their apex. Conversely, buried QDs were pseudomorphically grown on GaAs. By postulating a plane stress state, we have established a systematic increase of the local strain from the base toward the apex region of the QDs. Using Vegard's law, their chemical composition profiles were calculated, revealing an indium content gradient along the growth direction and compositional variants among different QDs. Photoluminescence measurements showed variations in emission energy between the QDs and consistency with a graded In-content, which complied with the quantitative strain analysis.« less

Molecular evaluation of microalgal communities in full-scale waste stabilisation ponds.

PubMed

Eland, Lucy E; Davenport, Russell J; Santos, Andre Bezerra Dos; Mota Filho, Cesar R

2018-02-22

Waste stabilisation ponds (WSPs) are widely used across the world as a passive wastewater treatment for domestic wastewaters, but little is known about their ecology, especially their phototrophic communities. This study uses molecular methods and flow cytometry to assess the cyanobacterial and eukaryotic communities longitudinally throughout two systems, one treating domestic wastewater and the other mixed industrial/domestic wastewaters. More variation was seen between the systems than between different stages in the treatment processes for both eukaryotic and cyanobacterial communities. Chlorella species and Planktophrix cyanobacteria dominated both treatment systems. Arthrospira cyanobacteria were detected only in the industrial/domestic system. The balance between non-photosynthetic and photosynthetic organisms is rarely considered, though both play vital roles in WSP functioning. Flow cytometry showed that the facultative and first maturation pond in the industrial system contained a lower proportion of photosynthetic organisms compared to the domestic system. This is reflected in the species richness data and low dissolved oxygen levels detected. All data indicated that both systems are significantly different from one another and that variation longitudinally throughout the systems is lower. A more systematic study is needed to determine if it is the wastewater source rather than the initial inoculum that drives community composition.

The Magmatic Structure of Mid-ocean Ridges: Integrating Geophysical and Petrological Observations

NASA Astrophysics Data System (ADS)

Maclennan, J.; Singh, S.

Geophysical surveys, petrological observations and numerical models have all played an important role in the study of magmatic processes at mid-ocean ridges. However, few studies have attempted to integrate the constraints from both geophysical and geochemical observations in order to develop models of mid-ocean ridges. Composi- tional variation within the oceanic crust must be considered when geophysical models are interpreted in terms of variation in temperature or fluid fraction. Modellers com- monly assume that the crust is compositionally homogeneous and that the relationship between temperature and melt fraction does not vary within the crust. However, the compositions of oceanic crustal rocks collected from the Oman ophiolite vary widely and their predicted solidus temperatures vary from 990­1240C and their liquidus temperatures from 1250­1700C. Compositional variation within the solid part of the oceanic crust causes variation in seismic velocities. At fixed temperature and pressure the compositional variation present in crustal rocks can give P-wave velocity variation of 1 km s-1 or more. This has the same effect as a temperature variation of 1500C in the solid or of a variation of 20% in the melt fraction. The importance of this petrolog- ical framework for the interpretation of the seismic structure of mid-ocean ridges and for the development of thermal models of oceanic crustal accretion is demonstrated using an example from the East Pacific Rise near 9N.

Pyroxene thermometry in the OPX Tongue of the Basement Sill, McMurdo Dry Valleys, Antarctica

NASA Astrophysics Data System (ADS)

Simon, A. C.; Marsh, B.

2005-12-01

Unusually large orthopyroxene (Opx) crystals (5 mm) in the 330 m thick doleritic Basement Sill, the basal sill of the Ferrar Dolerite sill complex, possess strong variations in modal abundance and size both across and along the sill length. Opx phenocrysts (with greatly subordinate cpx) are concentrated toward the middle of the sill, forming an extensive ultramafic tongue, which dominates the thickness of the sill in the feeder zone near Bull Pass and progressively thins with increasing distance in all directions away from the feeder zone. The chilled margins of the sill contain no Opx phenocrysts. Based on the physical position of the Opx tongue and the size, abundance and textural condition of these Opx crystals, it has been postulated that these Opx phenocrysts were entrained in the ascending magma after having been texturally equilibrated at a much deeper location than the present level of sill emplacement, approximately 3- 4 km paleodepth. Determining the ultimate provenance of these phenocrysts is an important step in understanding the formation and overall dynamics of this magmatic system. In a real sense these crystals are important dynamic tracers. To gain insight into the origin and history of transport of these crystals, we performed electron probe microanalyses of pyroxenes from samples collected at 15 m intervals through the entire Basement Sill near the feeder zone in West Bull Pass to quantify the compositions of pyroxenes both within the tongue and the bounding chilled margin in order to use crystal-chemical variations to infer crystal histories. Additionally, we calculated equilibrium temperatures for Opx - Cpx mineral pairs, using the QUILF projection scheme at 200 MPa, to determine if pyroxene crystals in the tongue reflect higher temperatures, indicative of crystallization at deeper levels of the sill-complex plumbing system. Despite some scatter in pyroxene compositions, the data indicate that the En (mole % MgSiO3) component of Opx and Cpx increases systematically with depth through the sill, reaching a plateau in the middle of the transect and then decreasing to the chilled margin at the base of the section. The range of En content of Cpx (27 En) is much less than that of Opx (40 En). The Di component of Cpx acts to some degree as a pivot for the varying En/Fs of Opx. The trend in the En component of Opx parallels roughly the trend in whole-rock MgO, the latter being a manifestation of the increase in abundance of En-rich Opx crystals (phenocrysts) in the central part of the sill. Intra-crystal compositional variation is minimal except for the (expected) decrease in En/Fs of grain margins, reflecting simply the iron enrichment of the residual melt with progressive crystallization. The concentrations of Cr and Al in Opx increase systematically with depth in the sill are highest in Opx of the tongue. Compositional tie-lines for Opx-Cpx pairs from the chilled margin and Opx-tongue, when plotted in the pyroxene quadrilateral, possess negative and positive slopes, respectively. Temperature data define a thermal maximum plateau that coincides with the position of the Opx-tongue; 2-pyroxene temperature increasing on the order of 200 degrees C between the chilled margin (900 to 1000 C)and the Opx-tongue (1070 to 1242 C). The pyroxene tongue represents a subsequent, higher temperature, intrusive event. The relatively high temperatures, trace element abundances, and textural information all suggest that the provenance of the crystals forming the Opx Tongue were entrained from a cumulate pile associated with an earlier magmatic event.

Investigating the Magneto Electric Coupling of [90 wt%Na0.5Bi0.5TiO3 (NBT)-10 wt% BaFe12O19 (BaM)] novel multiferroiccomposite system by increasing of BaM grain size

NASA Astrophysics Data System (ADS)

Pattanayak, Ranjit; Raut, Subhajit; Kuila, Sourav; Chandrasekhar, Mallam; Panigrahi, Simanchala

2017-02-01

Polycrystalline three novel [90 wt%Na0.5Bi0.5TiO3 (NBT)-10 wt% BaFe12O19 (BaM)] magnetoelctricmultiferroic composite systems were fabricated by considering the variation (increasing) of BaM grain size. The desired formation of composites was confirmed by X-ray diffraction study. The FESEM and SEM study were verified the variation of grain size and 0-3 type connectivity of composite systems. To predict the room temperature multiferroicbehaviour of theses composite systems we were taken PE and MH loop. For investigating the extrinsic and intrinsic magnetoelctric effect magneto impedance spectroscopy was considered for theses composite systems. The variation of intrinsic magnetoelctric coupling was predicted by proposing a simple mechanical model.

Protein composition correlates with the mechanical properties of spider ( Argiope trifasciata ) dragline silk.

PubMed

Marhabaie, Mohammad; Leeper, Thomas C; Blackledge, Todd A

2014-01-13

We investigated the natural variation in silk composition and mechanical performance of the orb-weaving spider Argiope trifasciata at multiple spatial and temporal scales in order to assess how protein composition contributes to the remarkable material properties of spider dragline silk. Major ampullate silk in orb-weaving spiders consists predominantly of two proteins (MaSp1 and MaSp2) with divergent amino acid compositions and functionally different microstructures. Adjusting the expression of these two proteins therefore provides spiders with a simple mechanism to alter the material properties of their silk. We first assessed the reliability and precision of the Waters AccQ-Tag amino acid composition analysis kit for determining the amino acid composition of small quantities of spider silk. We then tested how protein composition varied within single draglines, across draglines spun by the same spider on different days, and finally between spiders. Then, we correlated chemical composition with the material properties of dragline silk. Overall, we found that the chemical composition of major ampullate silk was in general homogeneous among individuals of the same population. Variation in chemical composition was not detectable within silk spun by a single spider on a single day. However, we found that variation within a single spider's silk across different days could, in rare instances, be greater than variation among individual spiders. Most of the variation in silk composition in our investigation resulted from a small number of outliers (three out of sixteen individuals) with a recent history of stress, suggesting stress affects silk production process in orb web spiders. Based on reported sequences for MaSp genes, we developed a gene expression model showing the covariation of the most abundant amino acids in major ampullate silk. Our gene expression model supports that dragline silk composition was mostly determined by the relative abundance of MaSp1 and MaSp2. Finally, we showed that silk composition (especially proline content) strongly correlated with some measures of mechanical performance, particularly how much fibers shrunk during supercontraction as well as their breaking strains. Our findings suggest that spiders are able to change the relative expression rates of different MaSp genes to produce silk fibers with different chemical compositions, and hence, different material properties.

Geochemistry of pyrite and chalcopyrite from an active black smoker in 49.6°E Southwest Indian Ridge

NASA Astrophysics Data System (ADS)

Yuan, Bo; Yang, Yaomin; Yu, Hongjun; Zhao, Yuexia; Ding, Qingfeng; Yang, Jichao; Tang, Xin

2017-06-01

Active hydrothermal chimneys, as the product of submarine hydrothermal activity, can be used to determine the fluid evolution and formation process of potential volcanic-hosted massive sulfide deposits. A hard-won specimen from an active hydrothermal chimney was collected in the 49.6°E ultraslow-spreading Southwest Indian Ridge (SWIR) field through a television-guided grab. A geochemical study of prominent sulfide (e.g., pyrite and chalcopyrite) included in this sample was performed using laser ablation inductively coupled plasma mass spectroscopy. The early sulfides produced at low temperature are of disseminated fine-grained anhedral morphology, whereas the late ones with massive, coarse euhedral features precipitated in a high-temperature setting. The systematic variations in the contents of minor and trace elements are apparently related to the crystallization sequence, as well as to texture. Micro-disseminated anhedral sulfides rich in Pb, As, Ni, Ba, Mn, Mo, U, and V were formed during the initial chimney wall growth, whereas those rich in Sn, Se, and Co with massive, coarse euhedral morphology were formed within the late metallogenic stage. The hydrothermal fluid composition has experienced a great change during the chimney growth. Such a conclusion is consistent with that indicated by using principal component analysis, which is a powerful statistical analysis method widely used to project multidimensional datasets (e.g., element contents in different mineral phases) into a few directions. This distribution pattern points to crystallographic controls on minor and trace element uptake during chimney growth, occurring with concomitant variations in the fluid composition evolutionary history. In this pyrite-chalcopyrite-bearing active hydrothermal chimney at the SWIR, the metal concentration and precipitation of sulfides largely occurred at the seafloor as a result of mixing between the upwelling hot hydrothermal fluid and cold seawater. Over the course of mixing, significant variations in metal solubility were caused by changes in temperature, pH, and redox conditions in the parental fluid phase.

Thallium isotope variations in an ore-bearing continental igneous setting: Collahuasi Formation, northern Chile

NASA Astrophysics Data System (ADS)

Baker, R. G. A.; Rehkämper, M.; Ihlenfeld, C.; Oates, C. J.; Coggon, R.

2010-08-01

Thallium is a highly incompatible element and a large fraction of the bulk silicate Earth Tl budget is, therefore, expected to reside in the continental crust. Nonetheless, the Tl isotope systematics of continental rocks are essentially unexplored at present. Here, we present new Tl isotope composition and concentration data for a suite of 36 intrusive and extrusive igneous rocks from the vicinity of porphyry Cu deposits in the Collahuasi Formation of the Central Andes in northern Chile. The igneous lithologies of the rocks are variably affected by the hydrothermal alteration that accompanied the formation of the Cu deposits. The samples display Tl concentrations that vary by more than an order of magnitude, from 0.1 to 3.2 μg/g, whilst ɛ 205Tl ranges between -5.1 and +0.1 (ɛ 205Tl is the deviation of the 205Tl/ 203Tl isotope ratio of a sample from a standard in parts per 10 4). These variations are primarily thought to be a consequence of hydrothermal alteration processes, including metasomatic transport of Tl, and formation/breakdown of Tl-bearing minerals, which are associated with small but significant Tl isotope effects. The Tl abundances show excellent correlations with both K and Rb concentrations but no co-variation with Cu. This demonstrates that Tl displays only limited chalcophile affinity in the continental crust of the Collahuasi Formation, but behaves as a lithophile element with a distribution that is primarily governed by partitioning of Tl + into K +-bearing phases. Collahuasi samples with propylitic alteration features, which are derived from the marginal parts of the hydrothermal systems, have, on average, slightly lighter Tl isotope compositions than rocks from the more central sericitic and argillic alteration zones. This small but statistically significant difference most likely reflects preferential retention of isotopically heavy Tl in alteration phases, such as white micas and clays, which formed during sericitic and argillic alteration.

Regional-Scale Drivers of Forest Structure and Function in Northwestern Amazonia

PubMed Central

Higgins, Mark A.; Asner, Gregory P.; Anderson, Christopher B.; Martin, Roberta E.; Knapp, David E.; Tupayachi, Raul; Perez, Eneas; Elespuru, Nydia; Alonso, Alfonso

2015-01-01

Field studies in Amazonia have found a relationship at continental scales between soil fertility and broad trends in forest structure and function. Little is known at regional scales, however, about how discrete patterns in forest structure or functional attributes map onto underlying edaphic or geological patterns. We collected airborne LiDAR (Light Detection and Ranging) data and VSWIR (Visible to Shortwave Infrared) imaging spectroscopy measurements over 600 km2 of northwestern Amazonian lowland forests. We also established 83 inventories of plant species composition and soil properties, distributed between two widespread geological formations. Using these data, we mapped forest structure and canopy reflectance, and compared them to patterns in plant species composition, soils, and underlying geology. We found that variations in soils and species composition explained up to 70% of variation in canopy height, and corresponded to profound changes in forest vertical profiles. We further found that soils and plant species composition explained more than 90% of the variation in canopy reflectance as measured by imaging spectroscopy, indicating edaphic and compositional control of canopy chemical properties. We last found that soils explained between 30% and 70% of the variation in gap frequency in these forests, depending on the height threshold used to define gaps. Our findings indicate that a relatively small number of edaphic and compositional variables, corresponding to underlying geology, may be responsible for variations in canopy structure and chemistry over large expanses of Amazonian forest. PMID:25793602

Analysis of Repeatability and Reliability of Warm IRAC Observations of Transiting Exoplanets

NASA Astrophysics Data System (ADS)

Carey, Sean J.; Krick, Jessica; Ingalls, James

2015-12-01

Extracting information about thermal profiles and composition of the atmospheres of transiting exoplanets is extremely challenging due to the small differential signal of the atmosphere in observations of transits, secondary eclipses, and full phase curves for exoplanets. The relevant signals are often at the level of 100 ppm or smaller and require the removal of significant instrumental systematics in the two infrared instruments currently capable of providing information at this precision, WFC3 on HST and IRAC aboard the Spitzer Space Telescope. For IRAC, the systematics are due to the interplay of residual telescope pointing variation with intra-pixel gain variations in the moderately undersampled camera. There is currently a debate in the community on the reliability of repeated IRAC observations of exoplanets particularly those in eclipse from which inferences about atmospheric temperature and pressure profiles can made. To assess the repeatability and reliability of post-cryogenic observations with IRAC, the Spitzer Science Center in conjunction with volunteers from the astronomical community has performed a systematic analysis of the removal of systematics and repeatability of warm IRAC observations. Recently, a data challenge consisting of the measurement of ten secondary eclipses of XO-3b (see Wong et al. 2014) and a complementary analysis of a synthetic version of the XO-3b data was undertaken. We report on the results of this data challenge. Five different techniques were applied to the data (BLISS mapping [Stevenson et al. (2012)], kernel regression using the science data [Wong et al. (2015)] and calibration data [Krick et al. (2015)], pixel-level decorrelation [Deming et al. (2015)], ICA [Morello et al. (2015)] and Gaussian Processes [Evans et al. (2015)]) and found consistent results in terms of eclipse depth and reliability in both the actual and synthetic data. In addition, each technique obtained the input eclipse depth in the simulated data within the stated measurement uncertainty. The reported uncertainties for each measurement approach the photon noise limit. These findings generally refute the results of Hansen et al. (2014) and suggest that inferences about atmospheric properties can be reasonably made using warm IRAC data. Application of our test methods to future observations using JWST (in particular the MIRI instrument) will be discussed.

Titanium stable isotopic variations in chondrites, achondrites and lunar rocks

NASA Astrophysics Data System (ADS)

Greber, Nicolas D.; Dauphas, Nicolas; Puchtel, Igor S.; Hofmann, Beda A.; Arndt, Nicholas T.

2017-09-01

Titanium isotopes are potential tracers of processes of evaporation/condensation in the solar nebula and magmatic differentiation in planetary bodies. To gain new insights into the processes that control Ti isotopic variations in planetary materials, 25 komatiites, 15 chondrites, 11 HED-clan meteorites, 5 angrites, 6 aubrites, a martian shergottite, and a KREEP-rich impact melt breccia have been analyzed for their mass-dependent Ti isotopic compositions, presented using the δ49Ti notation (deviation in permil of the 49Ti/47Ti ratio relative to the OL-Ti standard). No significant variation in δ49Ti is found among ordinary, enstatite, and carbonaceous chondrites, and the average chondritic δ49Ti value of +0.004 ± 0.010‰ is in excellent agreement with the published estimate for the bulk silicate Earth, the Moon, Mars, and the HED and angrite parent-bodies. The average δ49Ti value of komatiites of -0.001 ± 0.019‰ is also identical to that of the bulk silicate Earth and chondrites. OL-Ti has a Ti isotopic composition that is indistinguishable from chondrites and is therefore a suitable material for reporting δ49Ti values. Previously published isotope data on another highly refractory element, Ca, show measurable variations among chondrites. The decoupling between Ca and Ti isotope systematics most likely occurred during condensation in the solar nebula. Aubrites exhibit significant variations in δ49Ti, from -0.07 to +0.24‰. This is likely due to the uniquely reducing conditions under which the aubrite parent-body differentiated, allowing chalcophile Ti3+ and lithophile Ti4+ to co-exist. Consequently, the observed negative correlation between δ49Ti values and MgO concentrations among aubrites is interpreted to be the result of isotope fractionation driven by the different oxidation states of Ti in this environment, such that isotopically heavy Ti4+ was concentrated in the residual liquid during magmatic differentiation. Finally, KREEPy impact melt breccia SaU 169 exhibits a heavy δ49Ti value of +0.330 ± 0.034‰ which is interpreted to result from Ti isotopic fractionation during ilmenite precipitation in the late stages of lunar magma ocean crystallization. A Rayleigh distillation calculation predicts that a δ49Ti value of +0.330‰ is achieved after removal of 94% of Ti in ilmenite.

Spatio-temporal variation of fish taxonomic composition in a South-East Asian flood-pulse system.

PubMed

Kong, Heng; Chevalier, Mathieu; Laffaille, Pascal; Lek, Sovan

2017-01-01

The Tonle Sap Lake (TSL) is a flood-pulse system. It is the largest natural lake in South-East Asia and constitutes one of the largest fisheries over the world, supporting the livelihood of million peoples. Nonetheless, the Mekong River Basin is changing rapidly due to accelerating water infrastructure development (hydropower, irrigation, flood control, and water supply) and climate change, bringing considerable modifications to the annual flood-pulse of the TSL. Such modifications are expected to have strong impacts on fish biodiversity and abundance. This paper aims to characterize the spatio-temporal variations of fish taxonomic composition and to highlights the underlying determinants of these variations. For this purpose, we used data collected from a community catch monitoring program conducted at six sites during 141 weeks, covering two full hydrological cycles. For each week, we estimated beta diversity as the total variance of the site-by-species community matrix and partitioned it into Local Contribution to Beta Diversity (LCBD) and Species Contribution to Beta Diversity (SCBD). We then performed multiple linear regressions to determine whether species richness, species abundances and water level explained the temporal variation in the contribution of site and species to beta diversity. Our results indicate strong temporal variation of beta diversity due to differential contributions of sites and species to the spatial variation of fish taxonomic composition. We further found that the direction, the shape and the relative effect of species richness, abundances and water level on temporal variation in LCBD and SCBD values greatly varied among sites, thus suggesting spatial variation in the processes leading to temporal variation in community composition. Overall, our results suggest that fish taxonomic composition is not homogeneously distributed over space and time and is likely to be impacted in the future if the flood-pulse dynamic of the system is altered by human activities.

Effect of Population Heterogenization on the Reproducibility of Mouse Behavior: A Multi-Laboratory Study

PubMed Central

Richter, S. Helene; Garner, Joseph P.; Zipser, Benjamin; Lewejohann, Lars; Sachser, Norbert; Touma, Chadi; Schindler, Britta; Chourbaji, Sabine; Brandwein, Christiane; Gass, Peter; van Stipdonk, Niek; van der Harst, Johanneke; Spruijt, Berry; Võikar, Vootele; Wolfer, David P.; Würbel, Hanno

2011-01-01

In animal experiments, animals, husbandry and test procedures are traditionally standardized to maximize test sensitivity and minimize animal use, assuming that this will also guarantee reproducibility. However, by reducing within-experiment variation, standardization may limit inference to the specific experimental conditions. Indeed, we have recently shown in mice that standardization may generate spurious results in behavioral tests, accounting for poor reproducibility, and that this can be avoided by population heterogenization through systematic variation of experimental conditions. Here, we examined whether a simple form of heterogenization effectively improves reproducibility of test results in a multi-laboratory situation. Each of six laboratories independently ordered 64 female mice of two inbred strains (C57BL/6NCrl, DBA/2NCrl) and examined them for strain differences in five commonly used behavioral tests under two different experimental designs. In the standardized design, experimental conditions were standardized as much as possible in each laboratory, while they were systematically varied with respect to the animals' test age and cage enrichment in the heterogenized design. Although heterogenization tended to improve reproducibility by increasing within-experiment variation relative to between-experiment variation, the effect was too weak to account for the large variation between laboratories. However, our findings confirm the potential of systematic heterogenization for improving reproducibility of animal experiments and highlight the need for effective and practicable heterogenization strategies. PMID:21305027

Systematic, cross-cortex variation in neuron numbers in rodents and primates.

PubMed

Charvet, Christine J; Cahalane, Diarmuid J; Finlay, Barbara L

2015-01-01

Uniformity, local variability, and systematic variation in neuron numbers per unit of cortical surface area across species and cortical areas have been claimed to characterize the isocortex. Resolving these claims has been difficult, because species, techniques, and cortical areas vary across studies. We present a stereological assessment of neuron numbers in layers II-IV and V-VI per unit of cortical surface area across the isocortex in rodents (hamster, Mesocricetus auratus; agouti, Dasyprocta azarae; paca, Cuniculus paca) and primates (owl monkey, Aotus trivigratus; tamarin, Saguinus midas; capuchin, Cebus apella); these chosen to vary systematically in cortical size. The contributions of species, cortical areas, and techniques (stereology, "isotropic fractionator") to neuron estimates were assessed. Neurons per unit of cortical surface area increase across the rostro-caudal (RC) axis in primates (varying by a factor of 1.64-2.13 across the rostral and caudal poles) but less in rodents (varying by a factor of 1.15-1.54). Layer II-IV neurons account for most of this variation. When integrated into the context of species variation, and this RC gradient in neuron numbers, conflicts between studies can be accounted for. The RC variation in isocortical neurons in adulthood mirrors the gradients in neurogenesis duration in development. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Predicting biomass of hyperdiverse and structurally complex central Amazonian forests - a virtual approach using extensive field data

DOE PAGES

Magnabosco Marra, Daniel; Higuchi, Niro; Trumbore, Susan E.; ...

2016-03-11

Notice on corrigendum: This paper has a corresponding corrigendum published. Please read the corrigendum first. Old-growth forests are subject to substantial changes in structure and species composition due to the intensification of human activities, gradual climate change and extreme weather events. Trees store ca. 90 % of the total aboveground biomass (AGB) in tropical forests and precise tree biomass estimation models are crucial for management and conservation. In the central Amazon, predicting AGB at large spatial scales is a challenging task due to the heterogeneity of successional stages, high tree species diversity and inherent variations in tree allometry and architecture.more » We parameterized generic AGB estimation models applicable across species and a wide range of structural and compositional variation related to species sorting into height layers as well as frequent natural disturbances. We used 727 trees (diameter at breast height ≥ 5 cm) from 101 genera and at least 135 species harvested in a contiguous forest near Manaus, Brazil. Sampling from this data set we assembled six scenarios designed to span existing gradients in floristic composition and size distribution in order to select models that best predict AGB at the landscape level across successional gradients. We found that good individual tree model fits do not necessarily translate into reliable predictions of AGB at the landscape level. When predicting AGB (dry mass) over scenarios using our different models and an available pantropical model, we observed systematic biases ranging from -31 % (pantropical) to +39 %, with root-mean-square error (RMSE) values of up to 130 Mg ha -1 (pantropical). Our first and second best models had both low mean biases (0.8 and 3.9 %, respectively) and RMSE (9.4 and 18.6 Mg ha -1) when applied over scenarios. Predicting biomass correctly at the landscape level in hyperdiverse and structurally complex tropical forests, especially allowing good performance at the margins of data availability for model construction/calibration, requires the inclusion of predictors that express inherent variations in species architecture. The model of interest should comprise the floristic composition and size-distribution variability of the target forest, implying that even generic global or pantropical biomass estimation models can lead to strong biases. Reliable biomass assessments for the Amazon basin (i.e., secondary forests) still depend on the collection of allometric data at the local/regional scale and forest inventories including species-specific attributes, which are often unavailable or estimated imprecisely in most regions.« less

Corrigendum to "Predicting biomass of hyperdiverse and structurally complex central Amazonian forests — a virtual approach using extensive field data" Published in Biogeosciences, 13, 1553-1570, 2016

DOE PAGES

Magnabosco Marra, Daniel; Higuchi, Niro; Trumbore, Susan E.; ...

2016-04-27

Old-growth forests are subject to substantial changes in structure and species composition due to the intensification of human activities, gradual climate change and extreme weather events. Trees store ca. 90% of the total aboveground biomass (AGB) in tropical forests and precise tree biomass estimation models are crucial for management and conservation. In the central Amazon, predicting AGB at large spatial scales is a challenging task due to the heterogeneity of successional stages, high tree species diversity and inherent variations in tree allometry and architecture. We parameterized generic AGB estimation models applicable across species and a wide range of structural andmore » compositional variation related to species sorting into height layers as well as frequent natural disturbances. We used 727 trees (diameter at breast height ≥5 cm) from 101 genera and at least 135 species harvested in a contiguous forest near Manaus, Brazil. Sampling from this data set we assembled six scenarios designed to span existing gradients in floristic composition and size distribution in order to select models that best predict AGB at the landscape level across successional gradients. We found that good individual tree model fits do not necessarily translate into reliable predictions of AGB at the landscape level. We observed systematic biases ranging from -31% (pantropical) to +39 %, with root-mean-square error (RMSE) values of up to 130-Mg ha -1 (pantropical), when predicting AGB (dry mass) over scenarios using our different models and an available pantropical model. Our first and second best models had both low mean biases (0.8 and 3.9 %, respectively) and RMSE (9.4 and 18.6 Mg ha -1) when applied over scenarios. Predicting biomass correctly at the landscape level in hyperdiverse and structurally complex tropical forests, especially allowing good performance at the margins of data availability for model construction/calibration, requires the inclusion of predictors that express inherent variations in species architecture. Furthermore, the model of interest should comprise the floristic composition and size-distribution variability of the target forest, implying that even generic global or pantropical biomass estimation models can lead to strong biases. Reliable biomass assessments for the Amazon basin (i.e., secondary forests) still depend on the collection of allometric data at the local/regional scale and forest inventories including species-specific attributes, which are often unavailable or estimated imprecisely in most regions.« less

Corrigendum to "Predicting biomass of hyperdiverse and structurally complex central Amazonian forests — a virtual approach using extensive field data" Published in Biogeosciences, 13, 1553-1570, 2016

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

Magnabosco Marra, Daniel; Higuchi, Niro; Trumbore, Susan E.

Old-growth forests are subject to substantial changes in structure and species composition due to the intensification of human activities, gradual climate change and extreme weather events. Trees store ca. 90% of the total aboveground biomass (AGB) in tropical forests and precise tree biomass estimation models are crucial for management and conservation. In the central Amazon, predicting AGB at large spatial scales is a challenging task due to the heterogeneity of successional stages, high tree species diversity and inherent variations in tree allometry and architecture. We parameterized generic AGB estimation models applicable across species and a wide range of structural andmore » compositional variation related to species sorting into height layers as well as frequent natural disturbances. We used 727 trees (diameter at breast height ≥5 cm) from 101 genera and at least 135 species harvested in a contiguous forest near Manaus, Brazil. Sampling from this data set we assembled six scenarios designed to span existing gradients in floristic composition and size distribution in order to select models that best predict AGB at the landscape level across successional gradients. We found that good individual tree model fits do not necessarily translate into reliable predictions of AGB at the landscape level. We observed systematic biases ranging from -31% (pantropical) to +39 %, with root-mean-square error (RMSE) values of up to 130-Mg ha -1 (pantropical), when predicting AGB (dry mass) over scenarios using our different models and an available pantropical model. Our first and second best models had both low mean biases (0.8 and 3.9 %, respectively) and RMSE (9.4 and 18.6 Mg ha -1) when applied over scenarios. Predicting biomass correctly at the landscape level in hyperdiverse and structurally complex tropical forests, especially allowing good performance at the margins of data availability for model construction/calibration, requires the inclusion of predictors that express inherent variations in species architecture. Furthermore, the model of interest should comprise the floristic composition and size-distribution variability of the target forest, implying that even generic global or pantropical biomass estimation models can lead to strong biases. Reliable biomass assessments for the Amazon basin (i.e., secondary forests) still depend on the collection of allometric data at the local/regional scale and forest inventories including species-specific attributes, which are often unavailable or estimated imprecisely in most regions.« less

A combined basalt and peridotite perspective on 14 million years of melt generation at the Atlantis Bank segment of the Southwest Indian Ridge: Evidence for temporal changes in mantle dynamics?

USGS Publications Warehouse

Coogan, L.A.; Thompson, G.M.; MacLeod, C.J.; Dick, H.J.B.; Edwards, S.J.; Hosford, Scheirer A.; Barry, T.L.

2004-01-01

Little is known about temporal variations in melt generation and extraction at midocean ridges largely due to the paucity of sampling along flow lines. Here we present new whole-rock major and trace element data, and mineral and glass major element data, for 71 basaltic samples (lavas and dykes) and 23 peridotites from the same ridge segment (the Atlantis Bank segment of the Southwest Indian Ridge). These samples span an age range of almost 14 My and, in combination with the large amount of published data from this area, allow temporal variations in melting processes to be investigated. Basalts show systematic changes in incompatible trace element ratios with the older samples (from ???8-14 Ma) having more depleted incompatible trace element ratios than the younger ones. There is, however, no corresponding change in peridotite compositions. Peridotites come from the top of the melting column, where the extent of melting is highest, suggesting that the maximum degree of melting did not change over this interval of time. New and published Nd isotopic ratios of basalts, dykes and gabbros from this segment suggest that the average source composition has been approximately constant over this time interval. These data are most readily explained by a model in which the average source composition and temperature have not changed over the last 14 My, but the dynamics of mantle flow (active-to-passive) or melt extraction (less-to-more efficient extraction from the 'wings' of the melting column) has changed significantly. This hypothesised change in mantle dynamics occurs at roughly the same time as a change from a period of detachment faulting to 'normal' crustal accretion. We speculate that active mantle flow may impart sufficient shear stress on the base of the lithosphere to rotate the regional stress field and promote the formation of low angle normal faults. ?? 2004 Elsevier B.V. All rights reserved.

Large effect of membrane tension on the fluid-solid phase transitions of two-component phosphatidylcholine vesicles.

PubMed

Chen, Dong; Santore, Maria M

2014-01-07

Model phospholipid membranes and vesicles have long provided insight into the nature of confined materials and membranes while also providing a platform for drug delivery. The rich thermodynamic behavior and interesting domain shapes in these membranes have previously been mapped in extensive studies that vary temperature and composition; however, the thermodynamic impact of tension on bilayers has been restricted to recent reports of subtly reduced fluid-fluid transition temperatures. In two-component phosphatidylcholine unilamellar vesicles [1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)], we report a dramatic influence of tension on the fluid-solid transition and resulting phases: At fixed composition, systematic variations in tension produce differently shaped solid domains (striped or irregular hexagons), shift fluid-solid transition temperatures, and produce a triple-point-like intersection of coexistence curves at elevated tensions, about 3 mN/m for 30% DOPC/70% DPPC. Tension therefore represents a potential switch of microstructure in responsive engineered materials; it is an important morphology-determining variable in confined systems, and, in biological membranes, it may provide a means to regulate dynamic structure.

Iron Redox Systematics of Martian Magmas

NASA Technical Reports Server (NTRS)

Righter, K.; Danielson, L.; Martin, A.; Pando, K.; Sutton, S.; Newville, M.

2011-01-01

Martian magmas are known to be FeO-rich and the dominant FeO-bearing mineral at many sites visited by the Mars Exploration rovers (MER) is magnetite [1]. Morris et al. [1] propose that the magnetite appears to be igneous in origin, rather than of secondary origin. However, magnetite is not typically found in experimental studies of martian magmatic rocks [2,3]. Magnetite stability in terrestrial magmas is well understood, as are the stability of FeO and Fe2O3 in terrestrial magmas [4,5]. In order to better understand the variation of FeO and Fe2O3, and the stability of magnetite (and other FeO-bearing phases) in martian magmas we have undertaken an experimental study with two emphases. First we document the stability of magnetite with temperature and fO2 in a shergottite bulk composition. Second, we determine the FeO and Fe2O3 contents of the same shergottite bulk composition at 1 bar and variable fO2 at 1250 C, and at variable pressure. These two goals will help define not only magnetite stability, but pyroxene-melt equilibria that are also dependent upon fO2.

Solid-state dewetting of Au-Ni bi-layer films mediated through individual layer thickness and stacking sequence

NASA Astrophysics Data System (ADS)

Herz, Andreas; Theska, Felix; Rossberg, Diana; Kups, Thomas; Wang, Dong; Schaaf, Peter

2018-06-01

In the present work, the solid-state dewetting of Au-Ni bi-layer thin films deposited on SiO2/Si is systematically studied with respect to individual layer thickness and stacking sequence. For this purpose, a rapid heat treatment at medium temperatures is applied in order to examine void formation at the early stages of the dewetting. Compositional variations are realized by changing the thickness ratio of the bi-layer films, while the total thickness is maintained at 20 nm throughout the study. In the event of Au/Ni films annealed at 500 °C, crystal voids exposing the substrate are missing regardless of chemical composition. In reverse order, the number of voids per unit area in two-phase Au-Ni thin films is found to be governed by the amount of Au-rich material. At higher temperatures up to 650 °C, a decreased probability of nucleation comes at the expense of a major portion of cavities, resulting in the formation of bubbles in 15 nm Ni/5 nm Au bi-layers. Film buckling predominantly occurred at phase boundaries crossing the bubbles.

28SiO v = 0 J = 1-0 emission from evolved stars

NASA Astrophysics Data System (ADS)

de Vicente, P.; Bujarrabal, V.; Díaz-Pulido, A.; Albo, C.; Alcolea, J.; Barcia, A.; Barbas, L.; Bolaño, R.; Colomer, F.; Diez, M. C.; Gallego, J. D.; Gómez-González, J.; López-Fernández, I.; López-Fernández, J. A.; López-Pérez, J. A.; Malo, I.; Moreno, A.; Patino, M.; Serna, J. M.; Tercero, F.; Vaquero, B.

2016-05-01

Aims: Observations of 28SiO v = 0J = 1-0 line emission (7-mm wavelength) from asymptotic giant branch (AGB) stars show in some cases peculiar profiles, composed of a central intense component plus a wider plateau. Very similar profiles have been observed in CO lines from some AGB stars and most post-AGB nebulae and, in these cases, they are clearly associated with the presence of conspicuous axial symmetry and bipolar dynamics. We aim to systematically study the profile shape of 28SiO v = 0J = 1-0 lines in evolved stars and to discuss the origin of the composite profile structure. Methods: We present observations of 28SiO v = 0J = 1-0 emission in 28 evolved stars, including O-rich, C-rich, and S-type Mira-type variables, OH/IR stars, semiregular long-period variables, red supergiants and one yellow hypergiant. Most objects were observed in several epochs, over a total period of time of one and a half years. The observations were performed with the 40 m radio telescope of the Instituto Geográfico Nacional (IGN) in Yebes, Spain. Results: We find that the composite core plus plateau profiles are systematically present in O-rich Miras, OH/IR stars, and red supergiants. They are also found in one S-type Mira (χ Cyg) and in two semiregular variables (X Her and RS Cnc) that are known to show axial symmetry. In the other objects, the profiles are simpler and similar to those observed in other molecular lines. The composite structure appears in the objects in which SiO emission is thought to come from the very inner circumstellar layers, prior to dust formation. The central spectral feature is found to be systematically composed of a number of narrow spikes, except for X Her and RS Cnc, in which it shows a smooth shape that is very similar to that observed in CO emission. These spikes show a significant (and mostly chaotic) time variation, while in all cases the smooth components remain constant within the uncertainties. The profile shape could come from the superposition of standard wide profiles and a group of weak maser spikes confined to the central spectral regions because of tangential amplification. Alternatively, we speculate that the very similar profiles detected in objects that are known to be conspicuously axisymmetric, such as X Her and RS Cnc, and in O-rich Mira-type stars, such as IK Tau and TX Cam, may be indicative of the systematic presence of a significant axial symmetry in the very inner circumstellar shells around AGB stars; such symmetry would be independent of the presence of weak maser effects in the central spikes.

Molecular indicators for palaeoenvironmental change in a Messinian evaporitic sequence (Vena del Gesso, Italy). II: High-resolution variations in abundances and 13C contents of free and sulphur-bound carbon skeletons in a single marl bed

NASA Technical Reports Server (NTRS)

Kenig, F.; Damste, J. S.; Frewin, N. L.; Hayes, J. M.; De Leeuw, J. W.

1995-01-01

The extractable organic matter of 10 immature samples from a marl bed of one evaporitic cycle of the Vena del Gesso sediments (Gessoso-solfifera Fm., Messinian, Italy) was analyzed quantitatively for free hydrocarbons and organic sulphur compounds. Nickel boride was used as a desulphurizing agent to recover sulphur-bound lipids from the polar and asphaltene fractions. Carbon isotopic compositions (delta vs PDB) of free hydrocarbons and of S-bound hydrocarbons were also measured. Relationships between these carbon skeletons, precursor biolipids, and the organisms producing them could then be examined. Concentrations of S-bound lipids and free hydrocarbons and their delta values were plotted vs depth in the marl bed and the profiles were interpreted in terms of variations in source organisms, 13 C contents of the carbon source, and environmentally induced changes in isotopic fractionation. The overall range of delta values measured was 24.7%, from -11.6% for a component derived from green sulphur bacteria (Chlorobiaceae) to -36.3% for a lipid derived from purple sulphur bacteria (Chromatiaceae). Deconvolution of mixtures of components deriving from multiple sources (green and purple sulphur bacteria, coccolithophorids, microalgae and higher plants) was sometimes possible because both quantitative and isotopic data were available and because either the free or S-bound pool sometimes appeared to contain material from a single source. Several free n-alkanes and S-bound lipids appeared to be specific products of upper-water-column primary producers (i.e. algae and cyanobacteria). Others derived from anaerobic photoautotrophs and from heterotrophic protozoa (ciliates), which apparently fed partly on Chlorobiaceae. Four groups of n-alkanes produced by algae or cyanobacteria were also recognized based on systematic variations of abundance and isotopic composition with depth. For hydrocarbons probably derived from microalgae, isotopic variations are well correlated with those of total organic carbon. A resistant aliphatic biomacromolecule produced by microalgae is, therefore, probably an important component of the kerogen. These variations reflect changes in the depositional environment and early diagenetic transformations. Changes in the concentrations of S-bound lipids induced by variations in conditions favourable for sulphurization were discriminated from those related to variations in primary producer assemblages. The water column of the lagoonal basin was stratified and photic zone anoxia occurred during the early and middle stages of marl deposition. During the last stage of the marl deposition the stratification collapsed due to a significant shallowing of the water column. Contributions from anaerobic photoautotrophs were apparently associated with variations in depth of the chemocline.

Molecular indicators for palaeoenvironmental change in a Messinian evaporitic sequence (Vena del Gesso, Italy). II: High-resolution variations in abundances and 13C contents of free and sulphur-bound carbon skeletons in a single marl bed.

PubMed

Kenig, F; Damsté, J S; Frewin, N L; Hayes, J M; De Leeuw, J W

1995-06-01

The extractable organic matter of 10 immature samples from a marl bed of one evaporitic cycle of the Vena del Gesso sediments (Gessoso-solfifera Fm., Messinian, Italy) was analyzed quantitatively for free hydrocarbons and organic sulphur compounds. Nickel boride was used as a desulphurizing agent to recover sulphur-bound lipids from the polar and asphaltene fractions. Carbon isotopic compositions (delta vs PDB) of free hydrocarbons and of S-bound hydrocarbons were also measured. Relationships between these carbon skeletons, precursor biolipids, and the organisms producing them could then be examined. Concentrations of S-bound lipids and free hydrocarbons and their delta values were plotted vs depth in the marl bed and the profiles were interpreted in terms of variations in source organisms, 13 C contents of the carbon source, and environmentally induced changes in isotopic fractionation. The overall range of delta values measured was 24.7%, from -11.6% for a component derived from green sulphur bacteria (Chlorobiaceae) to -36.3% for a lipid derived from purple sulphur bacteria (Chromatiaceae). Deconvolution of mixtures of components deriving from multiple sources (green and purple sulphur bacteria, coccolithophorids, microalgae and higher plants) was sometimes possible because both quantitative and isotopic data were available and because either the free or S-bound pool sometimes appeared to contain material from a single source. Several free n-alkanes and S-bound lipids appeared to be specific products of upper-water-column primary producers (i.e. algae and cyanobacteria). Others derived from anaerobic photoautotrophs and from heterotrophic protozoa (ciliates), which apparently fed partly on Chlorobiaceae. Four groups of n-alkanes produced by algae or cyanobacteria were also recognized based on systematic variations of abundance and isotopic composition with depth. For hydrocarbons probably derived from microalgae, isotopic variations are well correlated with those of total organic carbon. A resistant aliphatic biomacromolecule produced by microalgae is, therefore, probably an important component of the kerogen. These variations reflect changes in the depositional environment and early diagenetic transformations. Changes in the concentrations of S-bound lipids induced by variations in conditions favourable for sulphurization were discriminated from those related to variations in primary producer assemblages. The water column of the lagoonal basin was stratified and photic zone anoxia occurred during the early and middle stages of marl deposition. During the last stage of the marl deposition the stratification collapsed due to a significant shallowing of the water column. Contributions from anaerobic photoautotrophs were apparently associated with variations in depth of the chemocline.

Soil biochar amendment shapes the composition of N2O-reducing microbial communities.

PubMed

Harter, Johannes; Weigold, Pascal; El-Hadidi, Mohamed; Huson, Daniel H; Kappler, Andreas; Behrens, Sebastian

2016-08-15

Soil biochar amendment has been described as a promising tool to improve soil quality, sequester carbon, and mitigate nitrous oxide (N2O) emissions. N2O is a potent greenhouse gas. The main sources of N2O in soils are microbially-mediated nitrogen transformation processes such as nitrification and denitrification. While previous studies have focused on the link between N2O emission mitigation and the abundance and activity of N2O-reducing microorganisms in biochar-amended soils, the impact of biochar on the taxonomic composition of the nosZ gene carrying soil microbial community has not been subject of systematic study to date. We used 454 pyrosequencing in order to study the microbial diversity in biochar-amended and biochar-free soil microcosms. We sequenced bacterial 16S rRNA gene amplicons as well as fragments of common (typical) nosZ genes and the recently described 'atypical' nosZ genes. The aim was to describe biochar-induced shifts in general bacterial community diversity and taxonomic variations among the nosZ gene containing N2O-reducing microbial communities. While soil biochar amendment significantly altered the 16S rRNA gene-based community composition and structure, it also led to the development of distinct functional traits capable of N2O reduction containing typical and atypical nosZ genes related to nosZ genes found in Pseudomonas stutzeri and Pedobacter saltans, respectively. Our results showed that biochar amendment can affect the relative abundance and taxonomic composition of N2O-reducing functional microbial traits in soil. Thus these findings broaden our knowledge on the impact of biochar on soil microbial community composition and nitrogen cycling. Copyright © 2016 Elsevier B.V. All rights reserved.

A systematic review of the effect of oral glucocorticoids on energy intake, appetite, and body weight in humans.

PubMed

Berthon, Bronwyn S; MacDonald-Wicks, Lesley K; Wood, Lisa G

2014-03-01

Obesity is a serious risk factor for chronic disease, and commonly prescribed oral glucocorticoids (OCS) may be contributing to the prevalence of obesity. The objective of this review was to assess the impact of OCS on obesity in humans through effects on body weight (BW), energy intake, appetite, and body composition. An electronic search of English language peer-reviewed studies from 1973 up to March 2012 was conducted using Medline, CINAHL, EMBASE, and Cochrane databases. Original studies that addressed the effects of OCS on appetite, energy intake, BW, or body composition in adults were considered eligible. Data from 21 studies with objectively measured outcomes were extracted and assessed for quality using standardized tools. The publication year varied from 1986 to 2013, and the sample size, from 6 to 189. Energy intake was measured in 6 studies; BW, in 19 studies; energy expenditure, in 3 studies; body composition, in 6 studies; and appetite was evaluated in 3 studies. Short-term oral glucocorticoid therapy may result in small increases in energy intake but does not appear to result in increased BW, possibly due to an increase in energy expenditure. Long-term therapy may result in clinically significant weight gain. Within-subject variation due to metabolism and physical activity levels confounds the relationship. A dose-response relationship of oral glucocorticoid therapy on energy intake, appetite, BW, or body composition was not found. Additional well-designed, double-blind, placebo-controlled clinical trials that use standardized doses of OCS and assess the effects on appetite, energy intake, BW, and composition are strongly justified to confirm the findings of this review. Copyright © 2014 Elsevier Inc. All rights reserved.

Zinc isotopes in sphalerite from base metal deposits in the Red Dog district, northern Alaska

USGS Publications Warehouse

Kelley, K.D.; Wilkinson, J.J.; Chapman, J.B.; Crowther, H.L.; Weiss, D.J.

2009-01-01

Analyses of sphalerite samples from shale-hosted massive sulfide and stratigraphically underlying vein breccia deposits in the Red Dog district in northern Alaska show a range ??66Zn values from zero to 0.60 per mil. The lowest values are observed in the vein breccia deposits, and the stratigraphically overlying (but structurally displaced) shale-hosted massive sulfide deposits show a systematic trend of increasing ??66Zn values from south to north (Main-Aqqaluk-Paalaaq-Anarraaq). The ??66Zn values are inversely correlated with sphalerite Fe/Mn ratio and also tend to be higher in low Cu sphalerite, consistent with precipitation of lower ??66Zn sphalerite closer to the principal hydrothermal fluid conduits. The most likely control on isotopic variation is Rayleigh fractionation during sulfide precipitation, with lighter zinc isotopes preferentially incorporated in the earliest sphalerite to precipitate from ore fluids at deeper levels (vein breccias) and close to the principal fluid conduits in the orebodies, followed by precipitation of sulfides with higher ??66Zn values in shallower and/or more distal parts of the flow path. There is no systematic variation among the paragenetic stages of sphalerite from a single deposit, suggesting an isotopically homogeneous zinc source and consistent transport-deposition conditions and/or dissolution-reprecipitation of earlier sphalerite without significant fractionation. Decoupled Zn and S isotope compositions are best explained by mixing of separate metal- and sulfur-bearing fluids at the depositional site. The results confirm that Zn isotopes may be a useful tracer for distinguishing between the central and distal parts of large hydrothermal systems as previously suggested and could therefore be of use in exploration. ?? 2009 by Economic Geology.

Genetic environment of germanium-bearing gold-silver vein ores from the Wolyu mine, Republic of Korea

NASA Astrophysics Data System (ADS)

Yun, Seong-Taek; So, Chil-Sup; Choi, Sang-Hoon; Shelton, Kevin L.; Koo, Ja-Hak

1993-04-01

The Wolyu mine is one of the largest vein-type gold-silver-bearing epithermal systems in the Youngdong district and is the first gold-silver deposit in Korea found to contain significant germanium, in the form of argyrodite (Ag8GeS6). Mineralized veins (78.9 ± 1.2 Ma) crosscutting Late Cretaceous hostrock tuff and quartz porphyry (81.5 ± 1.8 Ma) consist of three stages of quartz and carbonates, the first of which contains pyrite, basemetal sulfides and Au-Ag-minerals. Stage I Au-Ag-Ge-mineralized veins show a systematic variation of mineral assemblage with time: (1) quartz + pyrite; (2) quartz + pyrite + sphalerite + electrum + argentite; (3) carbonate + quartz + sphalerite + electrum + argentite; (4) carbonate + native silver + argentite + Ag-sulfosalts + argyrodite + sphalerite. Calculated values of temperature and sulfur activity are: assemblage (1), 360-280°C and 10-7-10-10; (2), 280-210°C and 10-10-10-14; (3), 210-180°C and 10-14-10-16; (4), 180-155°C and 10-17-10-18. These data, the frequent association of gold with sulfides, and the abundance of pyrite in alteration zones indicate that decreasing sulfur activity and cooling were important in triggering gold deposition. Hydrogen and oxygen isotope compositions of ore fluids display a systematic variation with increasing time. Within the main Ag-Au-Ge mineralization, δD and δ 18O values decrease with the transition from quartz to carbonate deposition (from -78 and -2.8% to -90 and -8.7%., respectively), indicating increasing involvement (mixing) of less evolved meteoric water which resulted in progressive cooling and dilution of ore fluids in the shallow (≈ 370 600 m) Wolyu epithermal system.

Multicompetence and Native Speaker Variation in Clausal Packaging in Japanese

ERIC Educational Resources Information Center

Brown, Amanda; Gullberg, Marianne

2012-01-01

Native speakers show systematic variation in a range of linguistic domains as a function of a variety of sociolinguistic variables. This article addresses native language variation in the context of multicompetence, i.e. knowledge of two languages in one mind (Cook, 1991). Descriptions of motion were elicited from functionally monolingual and…

Variational finite-difference methods in linear and nonlinear problems of the deformation of metallic and composite shells (review)

NASA Astrophysics Data System (ADS)

Maksimyuk, V. A.; Storozhuk, E. A.; Chernyshenko, I. S.

2012-11-01

Variational finite-difference methods of solving linear and nonlinear problems for thin and nonthin shells (plates) made of homogeneous isotropic (metallic) and orthotropic (composite) materials are analyzed and their classification principles and structure are discussed. Scalar and vector variational finite-difference methods that implement the Kirchhoff-Love hypotheses analytically or algorithmically using Lagrange multipliers are outlined. The Timoshenko hypotheses are implemented in a traditional way, i.e., analytically. The stress-strain state of metallic and composite shells of complex geometry is analyzed numerically. The numerical results are presented in the form of graphs and tables and used to assess the efficiency of using the variational finite-difference methods to solve linear and nonlinear problems of the statics of shells (plates)

Fatty acid composition in serum correlates with that in the liver and non-alcoholic fatty liver disease activity scores in mice fed a high-fat diet.

PubMed

Wang, Xing-He; Li, Chun-Yan; Muhammad, Ishfaq; Zhang, Xiu-Ying

2016-06-01

In this study, we investigated the correlation between the serum fatty acid composition and hepatic steatosis, inflammation, hepatocellular ballooning scores, and liver fatty acids composition in mice fed a high-fat diet. Livers were collected for non-alcoholic fatty liver disease score analysis. Fatty acid compositions were analysed by gas chromatography. Correlations were determined by Pearson correlation coefficient. Exposed to a high-fat diet, mice developed fatty liver disease with varying severity without fibrosis. The serum fatty acid variation became more severe with prolonged exposure to a high-fat diet. This variation also correlated significantly with the variation in livers, with the types of fatty acids corresponding to liver steatosis, inflammation, and hepatocellular ballooning scores. Results of this study lead to the following hypothesis: the extent of serum fatty acid variation may be a preliminary biomarker of fatty liver disease caused by high-fat intake. Copyright © 2016. Published by Elsevier B.V.

Variations in the gender composition of immigrant populations: how they matter.

PubMed

Donato, Katharine M; Alexander, Joseph T; Gabaccia, Donna R; Leinonen, Johanna

2011-01-01

This paper estimates and interprets empirical shifts in the gender composition of immigrants to add to scholarship about the gendering of international migrations over time. We map shifts in gender ratios using micro-level data that permit us to create age-standardized estimates among adult foreign born stock living in the United States since 1850 and in 26 other nations worldwide since 1960. We examine regional and national variations in these shifts, and ask whether and how the gendered composition of foreigners from diverse origins in the United States – the nation that has received the largest populations of migrants for over a century – differs from other nations that receive large numbers of immigrants. We also examine recent variations in gender ratios among immigrants living in six regional destination countries. Results show substantial variation in the gender composition of foreign-born populations, and they offer a starting point for examining causes and consequences in future research.

Spatial Evolution of the Thickness Variations over a CFRP Laminated Structure

NASA Astrophysics Data System (ADS)

Davila, Yves; Crouzeix, Laurent; Douchin, Bernard; Collombet, Francis; Grunevald, Yves-Henri

2017-10-01

Ply thickness is one of the main drivers of the structural performance of a composite part. For stress analysis calculations (e.g., finite element analysis), composite plies are commonly considered to have a constant thickness compared to the reality (coefficients of variation up to 9% of the mean ply thickness). Unless this variability is taken into account reliable property predictions cannot be made. A modelling approach of such variations is proposed using parameters obtained from a 16-ply quasi-isotropic CFRP plate cured in an autoclave. A discrete Fourier transform algorithm is used to analyse the frequency response of the observed ply and plate thickness profiles. The model inputs, obtained by a mathematical representation of the ply thickness profiles, permit the generation of a representative stratification considering the spatial continuity of the thickness variations that are in good agreement with the real ply profiles spread over the composite part. A residual deformation FE model of the composite plate is used to illustrate the feasibility of the approach.

Systematic Desensitization in Group Counseling Settings: An Overview

ERIC Educational Resources Information Center

Mayton, Daniel M., II; Atkinson, Donald R.

1974-01-01

This article summarizes research on systematic desensitization applied in group settings. Guidelines for use of group desensitization by college counselors are developed, and relevant sources regarding procedural variations cited. The need for research on group desensitization parameters is discussed. (Author)

Challenges in the determination of the interstellar flow longitude from the pickup ion cutoff

NASA Astrophysics Data System (ADS)

Taut, A.; Berger, L.; Möbius, E.; Drews, C.; Heidrich-Meisner, V.; Keilbach, D.; Lee, M. A.; Wimmer-Schweingruber, R. F.

2018-03-01

Context. The interstellar flow longitude corresponds to the Sun's direction of movement relative to the local interstellar medium. Thus, it constitutes a fundamental parameter for our understanding of the heliosphere and, in particular, its interaction with its surroundings, which is currently investigated by the Interstellar Boundary EXplorer (IBEX). One possibility to derive this parameter is based on pickup ions (PUIs) that are former neutral ions that have been ionized in the inner heliosphere. The neutrals enter the heliosphere as an interstellar wind from the direction of the Sun's movement against the partially ionized interstellar medium. PUIs carry information about the spatial variation of their neutral parent population (density and flow vector field) in their velocity distribution function. From the symmetry of the longitudinal flow velocity distribution, the interstellar flow longitude can be derived. Aim. The aim of this paper is to identify and eliminate systematic errors that are connected to this approach of measuring the interstellar flow longitude; we want to minimize any systematic influences on the result of this analysis and give a reasonable estimate for the uncertainty. Methods: We use He+ data measured by the PLAsma and SupraThermal Ion Composition (PLASTIC) sensor on the Solar TErrestrial RElations Observatory Ahead (STEREO A) spacecraft. We analyze a recent approach, identify sources of systematic errors, and propose solutions to eliminate them. Furthermore, a method is introduced to estimate the error associated with this approach. Additionally, we investigate how the selection of interplanetary magnetic field angles, which is closely connected to the pickup ion velocity distribution function, affects the result for the interstellar flow longitude. Results: We find that the revised analysis used to address part of the expected systematic effects obtains significantly different results than presented in the previous study. In particular, the derived uncertainties are considerably larger. Furthermore, an unexpected systematic trend of the resulting interstellar flow longitude with the selection of interplanetary magnetic field orientation is uncovered.

Timescale of Petrogenetic Processes Recorded in the Mount Perkins Magma System, Northern Colorado River Extension Corridor, Arizona

NASA Technical Reports Server (NTRS)

Danielson, Lisa R.; Metcalf, Rodney V.; Miller, Calvin F.; Rhodes Gregory T.; Wooden, J. L.

2013-01-01

The Miocene Mt. Perkins Pluton is a small composite intrusive body emplaced in the shallow crust as four separate phases during the earliest stages of crustal extension. Phase 1 (oldest) consists of isotropic hornblende gabbro and a layered cumulate sequence. Phase 2 consists of quartz monzonite to quartz monzodiorite hosting mafic microgranitoid enclaves. Phase 3 is composed of quartz monzonite and is subdivided into mafic enclave-rich zones and enclave-free zones. Phase 4 consists of aphanitic dikes of mafic, intermediate and felsic compositions hosting mafic enclaves. Phases 2-4 enclaves record significant isotopic disequilibrium with surrounding granitoid host rocks, but collectively enclaves and host rocks form a cogenetic suite exhibiting systematic variations in Nd-Sr-Pb isotopes that correlate with major and trace elements. Phases 2-4 record multiple episodes of magma mingling among cogenetic hybrid magmas that formed via magma mixing and fractional crystallization at a deeper crustal. The mafic end-member was alkali basalt similar to nearby 6-4 Ma basalt with enriched OIB-like trace elements and Nd-Sr-Pb isotopes. The felsic end-member was a subalkaline crustal-derived magma. Phase 1 isotropic gabbro exhibits elemental and isotopic compositional variations at relatively constant SiO2, suggesting generation of isotropic gabbro by an open-system process involving two mafic end-members. One end-member is similar in composition to the OIB-like mafic end-member for phases 2-4; the second is similar to nearby 11-8 Ma tholeiite basalt exhibiting low epsilon (sub Nd), and depleted incompatible trace elements. Phase 1 cumulates record in situ fractional crystallization of an OIB-like mafic magma with isotopic evidence of crustal contamination by partial melts generated in adjacent Proterozoic gneiss. The Mt Perkins pluton records a complex history in a lithospheric scale magma system involving two distinct mantle-derived mafic magmas and felsic magma sourced in the crust. Mixing and fractional crystallization of these magmas at various levels in the crust generated a suite of intermediate composition magmas. U-Pb zircon SHRIMP ages of phase 1 (15.7 +/- 0.2 Ma), phase 3 (15.8 +/- 0.2 Ma) and phase 4 (15.4 +/- 0.3 Ma) document a 100-300k year timescale for petrogenetic processes recorded in the Mt Perkins magma system.

Spatially controlled Fe and Si isotope variations: an alternative view on the formation of the Torres del Paine pluton

NASA Astrophysics Data System (ADS)

Gajos, Norbert A.; Lundstrom, Craig C.; Taylor, Alexander H.

2016-11-01

We present new Fe and Si isotope ratio data for the Torres del Paine igneous complex in southern Chile. The multi-composition pluton consists of an approximately 1 km vertical exposure of homogenous granite overlying a contemporaneous 250-m-thick mafic gabbro suite. This first-of-its-kind spatially dependent Fe and Si isotope investigation of a convergent margin-related pluton aims to understand the nature of granite and silicic igneous rock formation. Results collected by MC-ICP-MS show a trend of increasing δ56Fe and δ30Si with increasing silica content as well as a systematic increase in δ56Fe away from the mafic base of the pluton. The marginal Torres del Paine granites have heavier Fe isotope signatures (δ56Fe = +0.25 ± 0.02 2se) compared to granites found in the interior pluton (δ56Fe = +0.17 ± 0.02 2se). Cerro Toro country rock values are isotopically light in both Fe and Si isotopic systems (δ56Fe = +0.05 ± 0.02 ‰; δ30Si = -0.38 ± 0.07 ‰). The variations in the Fe and Si isotopic data cannot be accounted for by local assimilation of the wall rocks, in situ fractional crystallization, late-stage fluid exsolution or some combination of these processes. Instead, we conclude that thermal diffusion or source magma variation is the most likely process producing Fe isotope ratio variations in the Torres del Paine pluton.

Radial mixing and Ru-Mo isotope systematics under different accretion scenarios

NASA Astrophysics Data System (ADS)

Fischer, Rebecca A.; Nimmo, Francis; O'Brien, David P.

2018-01-01

The Ru-Mo isotopic compositions of inner Solar System bodies may reflect the provenance of accreted material and how it evolved with time, both of which are controlled by the accretion scenario these bodies experienced. Here we use a total of 116 N-body simulations of terrestrial planet accretion, run in the Eccentric Jupiter and Saturn (EJS), Circular Jupiter and Saturn (CJS), and Grand Tack scenarios, to model the Ru-Mo anomalies of Earth, Mars, and Theia analogues. This model starts by applying an initial step function in Ru-Mo isotopic composition, with compositions reflecting those in meteorites, and traces compositional evolution as planets accrete. The mass-weighted provenance of the resulting planets reveals more radial mixing in Grand Tack simulations than in EJS/CJS simulations, and more efficient mixing among late-accreted material than during the main phase of accretion in EJS/CJS simulations. We find that an extensive homogeneous inner disk region is required to reproduce Earth's observed Ru-Mo composition. EJS/CJS simulations require a homogeneous reservoir in the inner disk extending to ≥3-4 AU (≥74-98% of initial mass) to reproduce Earth's composition, while Grand Tack simulations require a homogeneous reservoir extending to ≥3-10 AU (≥97-99% of initial mass), and likely to ≥6-10 AU. In the Grand Tack model, Jupiter's initial location (the most likely location for a discontinuity in isotopic composition) is ∼3.5 AU; however, this step location has only a 33% likelihood of producing an Earth with the correct Ru-Mo isotopic signature for the most plausible model conditions. Our results give the testable predictions that Mars has zero Ru anomaly and small or zero Mo anomaly, and the Moon has zero Mo anomaly. These predictions are insensitive to wide variations in parameter choices.

Incorporation of Damage and Failure into an Orthotropic Elasto-Plastic Three-Dimensional Model with Tabulated Input Suitable for Use in Composite Impact Problems

NASA Technical Reports Server (NTRS)

Goldberg, Robert K.; Carney, Kelly S.; Dubois, Paul; Hoffarth, Canio; Khaled, Bilal; Rajan, Subramaniam; Blankenhorn, Gunther

2016-01-01

A material model which incorporates several key capabilities which have been identified by the aerospace community as lacking in the composite impact models currently available in LS-DYNA(Registered Trademark) is under development. In particular, the material model, which is being implemented as MAT 213 into a tailored version of LS-DYNA being jointly developed by the FAA and NASA, incorporates both plasticity and damage within the material model, utilizes experimentally based tabulated input to define the evolution of plasticity and damage as opposed to specifying discrete input parameters (such as modulus and strength), and is able to analyze the response of composites composed with a variety of fiber architectures. The plasticity portion of the orthotropic, three-dimensional, macroscopic composite constitutive model is based on an extension of the Tsai-Wu composite failure model into a generalized yield function with a non-associative flow rule. The capability to account for the rate and temperature dependent deformation response of composites has also been incorporated into the material model. For the damage model, a strain equivalent formulation is utilized to allow for the uncoupling of the deformation and damage analyses. In the damage model, a diagonal damage tensor is defined to account for the directionally dependent variation of damage. However, in composites it has been found that loading in one direction can lead to damage in multiple coordinate directions. To account for this phenomena, the terms in the damage matrix are semi-coupled such that the damage in a particular coordinate direction is a function of the stresses and plastic strains in all of the coordinate directions. The onset of material failure, and thus element deletion, is being developed to be a function of the stresses and plastic strains in the various coordinate directions. Systematic procedures are being developed to generate the required input parameters based on the results of experimental tests.

Systematic review: body composition in adults with inflammatory bowel disease.

PubMed

Bryant, R V; Trott, M J; Bartholomeusz, F D; Andrews, J M

2013-08-01

There is a paucity of data on body composition in patients with inflammatory bowel disease (IBD). Alterations of fat and muscle may affect bone health, muscle performance, quality of life (QoL) and overall morbidity. To systematically review the literature on body composition in adults with IBD, and to discuss potential contributory factors and associations. A systematic search was performed in July 2012 of OVID SP MEDLINE, OVID EMBASE and National Library of Medicine's PubMed Central Medline (Limitations: English, humans, from 1992). A total of 19 articles comparing body composition in patients with IBD with healthy age- and sex-matched control populations were included in the primary analysis. A total of 631 patients with Crohn's disease (CD) and 295 with ulcerative colitis (UC), mean age 37.1 (s.d. ± 9.2) years; 485 (52%) female, were reported upon. Data were heterogeneous and methodology varied. Compared with controls, a statistically significant reduction in body mass index (BMI) was reported in 37% of CD and 20% of UC patients; reduced fat-free mass in 28% CD and 13% UC patients, and reduced fat mass in 31% CD and 13% UC patients. There was no consistent association between body composition and disease activity, duration, extent or therapies. BMI did not accurately predict body composition. Current data, although heterogeneous, suggest that many patients with IBD are affected by aberrations in fat and lean mass, which may not be detected during routine clinical assessment. The prevalence and impact of altered body composition amongst this population warrant further investigation. © 2013 John Wiley & Sons Ltd.

Compositional symbol grounding for motor patterns.

PubMed

Greco, Alberto; Caneva, Claudio

2010-01-01

We developed a new experimental and simulative paradigm to study the establishing of compositional grounded representations for motor patterns. Participants learned to associate non-sense arm motor patterns, performed in three different hand postures, with non-sense words. There were two group conditions: in the first (compositional), each pattern was associated with a two-word (verb-adverb) sentence; in the second (holistic), each same pattern was associated with a unique word. Two experiments were performed. In the first, motor pattern recognition and naming were tested in the two conditions. Results showed that verbal compositionality had no role in recognition and that the main source of confusability in this task came from discriminating hand postures. As the naming task resulted too difficult, some changes in the learning procedure were implemented in the second experiment. In this experiment, the compositional group achieved better results in naming motor patterns especially for patterns where hand postures discrimination was relevant. In order to ascertain the differential effect, upon this result, of memory load and of systematic grounding, neural network simulations were also made. After a basic simulation that worked as a good model of subjects performance, in following simulations the number of stimuli (motor patterns and words) was increased and the systematic association between words and patterns was disrupted, while keeping the same number of words and syntax. Results showed that in both conditions the advantage for the compositional condition significantly increased. These simulations showed that the advantage for this condition may be more related to the systematicity rather than to the mere informational gain. All results are discussed in connection to the possible support of the hypothesis of a compositional motor representation and toward a more precise explanation of the factors that make compositional representations working.

Lactation Stage-Dependency of the Sow Milk Microbiota

PubMed Central

Chen, Wei; Mi, Jiandui; Lv, Ning; Gao, Jinming; Cheng, Jian; Wu, Ruiting; Ma, Jingyun; Lan, Tian; Liao, Xindi

2018-01-01

Breast milk is essential for the initial development of neonatal animals, as it provides not only essential nutrients and a broad range of bioactive compounds but also commensal bacteria. The milk microbiota contributes to the “initial” intestinal microbiota of infants and also plays a crucial role in modulating and influencing neonatal health. However, the milk microbiota of sows has yet to be systematically investigated. The goal of the present study was to characterize variations in bacterial diversity and composition in sow milk over the duration of lactation using a high-throughput sequencing approach. Milk samples (n = 160) were collected from 20 healthy sows at eight different time points, and microbial profiles were analyzed by 16S ribosomal RNA (rRNA) sequencing using the Illumina MiSeq platform. The composition and diversity of the milk microbiota changed significantly in colostrum but was relatively stable in transitional and mature milk. Firmicutes and Proteobacteria were the most dominant phyla in sow milk. The relative abundances of the two most dominant bacterial genera, Corynebacterium and Streptococcus, were significantly higher in colostrum than in transitional milk and mature milk samples, and the other four most dominant bacterial taxa (Lactobacillus, two unclassified genera in the families Ruminococcaceae and Lachnospiraceae, and an unclassified genus in the order Clostridiales) demonstrated higher relative abundances in transitional and mature milk than in colostrum. Membrane transport, amino acid metabolism and carbohydrate metabolism were the most abundant functional categories in sow milk communities. Microbial network analysis based on the predominant genera revealed that the abundance of Helcococcus was negatively correlated with the abundances of most other genera in sow milk. Our results are the first to systematically indicate that the sow milk microbiota is a dynamic ecosystem in which changes mainly occur in the colostrum and remain generally stable throughout lactation. PMID:29867853

Dielectric studies on PEG-LTMS based polymer composites

NASA Astrophysics Data System (ADS)

Patil, Ravikumar V.; Praveen, D.; Damle, R.

2018-02-01

PEG LTMS based polymer composites were prepared and studied for dielectric constant variation with frequency and temperature as a potential candidate with better dielectric properties. Solution cast technique is used for the preparation of polymer composite with five different compositions. Samples show variation in dielectric constant with frequency and temperature. Dielectric constant is large at low frequencies and higher temperatures. Samples with larger space charges have shown larger dielectric constant. The highest dielectric constant observed was about 29244 for PEG25LTMS sample at 100Hz and 312 K.

Stochastic analysis of experimentally determined physical parameters of HPMC:NiCl{sub 2} polymer composites

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

Thejas, Urs G.; Somashekar, R., E-mail: rs@physics.uni-mysore.ac.in; Sangappa, Y.

A stochastic approach to explain the variation of physical parameters in polymer composites is discussed in this study. We have given a statistical model to derive the characteristic variation of physical parameters as a function of dopant concentration. Results of X-ray diffraction study and conductivity have been taken to validate this function, which can be extended to any of the physical parameters and polymer composites. For this study we have considered a polymer composites of HPMC doped with various concentrations of Nickel Chloride.

Variations in thermospheric composition: A model based on mass-spectrometer and satellite-drag data

NASA Technical Reports Server (NTRS)

Jacchia, L. G.

1973-01-01

The seasonal-latitudinal and the diurnal variations of composition observed by mass spectrometers on the OGO 6 satellite are represented by two simple empirical formulae, each of which uses only one numerical parameter. The formulae are of a very general nature and predict the behavior of these variations at all heights and for all levels of solar activity; they yield a satisfactory representation of the corresponding variations in total density as derived from satellite drag. It is suggested that a seasonal variation of hydrogen might explain the abnormally low hydrogen densities at high northern latitudes in July 1964.

Li/Ag 2VO 2PO 4 batteries: the roles of composite electrode constituents on electrochemistry

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

Bock, David C.; Bruck, Andrea M.; Pelliccione, Christopher J.

2016-11-01

Silver vanadium phosphorous oxide, Ag 2V 2OPO 4, was used as a model system to systematically study the impact on the constituents of a composite electrode, including polymeric and conductive additives, on electrochemistry. Three different electrode compositions were investigated.

Prevalence of menopausal symptoms in Asian midlife women: a systematic review.

PubMed

Islam, M Rakibul; Gartoulla, P; Bell, R J; Fradkin, P; Davis, S R

2015-04-01

To systematically review published articles for the prevalence of menopausal symptoms in Asian women. A comprehensive and systematic literature search was performed using MEDLINE, EMBASE, PsycINFO, CINAHL, SCOPUS and Google scholar in June 2013 to retrieve all English-language studies that included information on the prevalence of menopausal symptoms in women living in Asian countries. Risk of bias of included studies was assessed using a risk-of-bias tool explicitly designed for the systematic review of prevalence studies. Twenty-three independent studies met our inclusion criteria. Physical symptoms were the most prevalent symptoms compared to psychological, vasomotor and sexual symptoms. There was a wide variation in the prevalence of all symptoms across the menopausal stages due to the differences in modes of recruitment, study design, sampling procedures, the time frame over which symptoms were assessed and use of different diagnostic or screening tools. A high level of bias was observed for both external and internal validity for most studies. Although there is a wide variation in the reported prevalence of menopausal symptoms, physical symptoms predominate, followed by psychological symptoms, vasomotor symptoms and sexual symptoms. Further studies of representative samples are necessary to understand whether the variations in prevalence reporting are a function of methodological issues or due to ethnic, cultural or other socioeconomic differences.

Elevational Gradients in β-Diversity Reflect Variation in the Strength of Local Community Assembly Mechanisms across Spatial Scales

PubMed Central

Tello, J. Sebastián; Myers, Jonathan A.; Macía, Manuel J.; Fuentes, Alfredo F.; Cayola, Leslie; Arellano, Gabriel; Loza, M. Isabel; Torrez, Vania; Cornejo, Maritza; Miranda, Tatiana B.; Jørgensen, Peter M.

2015-01-01

Despite long-standing interest in elevational-diversity gradients, little is known about the processes that cause changes in the compositional variation of communities (β-diversity) across elevations. Recent studies have suggested that β-diversity gradients are driven by variation in species pools, rather than by variation in the strength of local community assembly mechanisms such as dispersal limitation, environmental filtering, or local biotic interactions. However, tests of this hypothesis have been limited to very small spatial scales that limit inferences about how the relative importance of assembly mechanisms may change across spatial scales. Here, we test the hypothesis that scale-dependent community assembly mechanisms shape biogeographic β-diversity gradients using one of the most well-characterized elevational gradients of tropical plant diversity. Using an extensive dataset on woody plant distributions along a 4,000-m elevational gradient in the Bolivian Andes, we compared observed patterns of β-diversity to null-model expectations. β-deviations (standardized differences from null values) were used to measure the relative effects of local community assembly mechanisms after removing sampling effects caused by variation in species pools. To test for scale-dependency, we compared elevational gradients at two contrasting spatial scales that differed in the size of local assemblages and regions by at least an order of magnitude. Elevational gradients in β-diversity persisted after accounting for regional variation in species pools. Moreover, the elevational gradient in β-deviations changed with spatial scale. At small scales, local assembly mechanisms were detectable, but variation in species pools accounted for most of the elevational gradient in β-diversity. At large spatial scales, in contrast, local assembly mechanisms were a dominant force driving changes in β-diversity. In contrast to the hypothesis that variation in species pools alone drives β-diversity gradients, we show that local community assembly mechanisms contribute strongly to systematic changes in β-diversity across elevations. We conclude that scale-dependent variation in community assembly mechanisms underlies these iconic gradients in global biodiversity. PMID:25803846

Characterization of variability in pork carcass composition and primal quality

USDA-ARS?s Scientific Manuscript database

The objective was to characterize the factors and production practices that contribute to variation in pork composition and quality. It is possible the variation in pork quality traits, such as color, marbling, and tenderness, contributes to reduced customer confidence in the predictability of finis...

Shifts in tree functional composition amplify the response of forest biomass to climate

NASA Astrophysics Data System (ADS)

Zhang, Tao; Niinemets, Ülo; Sheffield, Justin; Lichstein, Jeremy W.

2018-04-01

Forests have a key role in global ecosystems, hosting much of the world’s terrestrial biodiversity and acting as a net sink for atmospheric carbon. These and other ecosystem services that are provided by forests may be sensitive to climate change as well as climate variability on shorter time scales (for example, annual to decadal). Previous studies have documented responses of forest ecosystems to climate change and climate variability, including drought-induced increases in tree mortality rates. However, relationships between forest biomass, tree species composition and climate variability have not been quantified across a large region using systematically sampled data. Here we use systematic forest inventories from the 1980s and 2000s across the eastern USA to show that forest biomass responds to decadal-scale changes in water deficit, and that this biomass response is amplified by concurrent changes in community-mean drought tolerance, a functionally important aspect of tree species composition. The amplification of the direct effects of water stress on biomass occurs because water stress tends to induce a shift in tree species composition towards species that are more tolerant to drought but are slower growing. These results demonstrate concurrent changes in forest species composition and biomass carbon storage across a large, systematically sampled region, and highlight the potential for climate-induced changes in forest ecosystems across the world, resulting from both direct effects of climate on forest biomass and indirect effects mediated by shifts in species composition.

Shifts in tree functional composition amplify the response of forest biomass to climate.

PubMed

Zhang, Tao; Niinemets, Ülo; Sheffield, Justin; Lichstein, Jeremy W

2018-04-05

Forests have a key role in global ecosystems, hosting much of the world's terrestrial biodiversity and acting as a net sink for atmospheric carbon. These and other ecosystem services that are provided by forests may be sensitive to climate change as well as climate variability on shorter time scales (for example, annual to decadal). Previous studies have documented responses of forest ecosystems to climate change and climate variability, including drought-induced increases in tree mortality rates. However, relationships between forest biomass, tree species composition and climate variability have not been quantified across a large region using systematically sampled data. Here we use systematic forest inventories from the 1980s and 2000s across the eastern USA to show that forest biomass responds to decadal-scale changes in water deficit, and that this biomass response is amplified by concurrent changes in community-mean drought tolerance, a functionally important aspect of tree species composition. The amplification of the direct effects of water stress on biomass occurs because water stress tends to induce a shift in tree species composition towards species that are more tolerant to drought but are slower growing. These results demonstrate concurrent changes in forest species composition and biomass carbon storage across a large, systematically sampled region, and highlight the potential for climate-induced changes in forest ecosystems across the world, resulting from both direct effects of climate on forest biomass and indirect effects mediated by shifts in species composition.

The oligocene Lund Tuff, Great Basin, USA: A very large volume monotonous intermediate

USGS Publications Warehouse

Maughan, L.L.; Christiansen, E.H.; Best, M.G.; Gromme, C.S.; Deino, A.L.; Tingey, D.G.

2002-01-01

Unusual monotonous intermediate ignimbrites consist of phenocryst-rich dacite that occurs as very large volume (> 1000 km3) deposits that lack systematic compositional zonation, comagmatic rhyolite precursors, and underlying plinian beds. They are distinct from countless, usually smaller volume, zoned rhyolite-dacite-andesite deposits that are conventionally believed to have erupted from magma chambers in which thermal and compositional gradients were established because of sidewall crystallization and associated convective fractionation. Despite their great volume, or because of it, monotonous intermediates have received little attention. Documentation of the stratigraphy, composition, and geologic setting of the Lund Tuff - one of four monotonous intermediate tuffs in the middle-Tertiary Great Basin ignimbrite province - provides insight into its unusual origin and, by implication, the origin of other similar monotonous intermediates. The Lund Tuff is a single cooling unit with normal magnetic polarity whose volume likely exceeded 3000 km3. It was emplaced 29.02 ?? 0.04 Ma in and around the coeval White Rock caldera which has an unextended north-south diameter of about 50 km. The tuff is monotonous in that its phenocryst assemblage is virtually uniform throughout the deposit: plagioclase > quartz ??? hornblende > biotite > Fe-Ti oxides ??? sanidine > titanite, zircon, and apatite. However, ratios of phenocrysts vary by as much as an order of magnitude in a manner consistent with progressive crystallization in the pre-eruption chamber. A significant range in whole-rock chemical composition (e.g., 63-71 wt% SiO2) is poorly correlated with phenocryst abundance. These compositional attributes cannot have been caused wholly by winnowing of glass from phenocrysts during eruption, as has been suggested for the monotonous intermediate Fish Canyon Tuff. Pumice fragments are also crystal-rich, and chemically and mineralogically indistinguishable from bulk tuff. We postulate that convective mixing in a sill-like magma chamber precluded development of a zoned chamber with a rhyolitic top or of a zoned pyroclastic deposit. Chemical variations in the Lund Tuff are consistent with equilibrium crystallization of a parental dacitic magma followed by eruptive mixing of compositionally diverse crystals and high-silica rhyolite vitroclasts during evacuation and emplacement. This model contrasts with the more systematic withdrawal from a bottle-shaped chamber in which sidewall crystallization creates a marked vertical compositional gradient and a substantial volume of capping-evolved rhyolite magma. Eruption at exceptionally high discharge rates precluded development of an underlying plinian deposit. The generation of the monotonous intermediate Lund magma and others like it in the middle Tertiary of the western USA reflects an unusually high flux of mantle-derived mafic magma into unusually thick and warm crust above a subducting slab of oceanic lithosphere. ?? 2002 Elsevier Science B.V. All rights reserved.

Voyager Observations of the Color of Saturn's Ring

NASA Technical Reports Server (NTRS)

Estrada, Paul R.; Cuzzi, Jeffrey N.; Morrison, David (Technical Monitor)

1994-01-01

Previously unreduced high resolution Voyager 2 images of Saturn's main rings are used to generate reflectivity (I/F) profiles as a function of radius. Ratios of profiles taken from green, violet, orange, and UV filter images are then produced. The I/F ratios are diagnostic of composition, and provide us with information on the rings' present state of compositional evolution. The rings are extremely reddish in color which suggests that they could not be pure water ice. The most likely candidates for the non-icy components are silicates and organics. The sources of these pollutants are of extreme importance in determining the compositional history of the rings. The radial profiles of ring color ratio exhibit several very interesting properties: (a) broad-scale, fairly smooth, color variations which are only weakly correlated with underlying ring structure (optical depth variations) across the outer C ring and inner B ring as well as the Cassini division region. These variations are probably consistent with ballistic transport; (b) fine-scale, noise-Like (but unquestionably real) color variations across at least the outer two-thirds of the B ring. Not only the "redness" but the spectral shape varies. These variations are currently unexplained. Groundbased spectroscopic observations should be pursued to study the implied compositional heterogeneities on at least the larger scales. This data set will be used for modeling of the color and composition of the main rings using ballistic transport and radiative transfer theories.

Variation in coastal Antarctic microbial community composition at sub-mesoscale: spatial distance or environmental filtering?

PubMed

Moreno-Pino, Mario; De la Iglesia, Rodrigo; Valdivia, Nelson; Henríquez-Castilo, Carlos; Galán, Alexander; Díez, Beatriz; Trefault, Nicole

2016-07-01

Spatial environmental heterogeneity influences diversity of organisms at different scales. Environmental filtering suggests that local environmental conditions provide habitat-specific scenarios for niche requirements, ultimately determining the composition of local communities. In this work, we analyze the spatial variation of microbial communities across environmental gradients of sea surface temperature, salinity and photosynthetically active radiation and spatial distance in Fildes Bay, King George Island, Antarctica. We hypothesize that environmental filters are the main control of the spatial variation of these communities. Thus, strong relationships between community composition and environmental variation and weak relationships between community composition and spatial distance are expected. Combining physical characterization of the water column, cell counts by flow cytometry, small ribosomal subunit genes fingerprinting and next generation sequencing, we contrast the abundance and composition of photosynthetic eukaryotes and heterotrophic bacterial local communities at a submesoscale. Our results indicate that the strength of the environmental controls differed markedly between eukaryotes and bacterial communities. Whereas eukaryotic photosynthetic assemblages responded weakly to environmental variability, bacteria respond promptly to fine-scale environmental changes in this polar marine system. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Whole body-element composition of Atlantic salmon Salmo salar influenced by migration direction and life stage in three distinct populations.

PubMed

Ebel, J D; Leroux, S J; Robertson, M J; Dempson, J B

2016-11-01

Body-element content was measured for three life stages of wild Atlantic salmon Salmo salar from three distinct Newfoundland populations as individuals crossed between freshwater and marine ecosystems. Life stage explained most of the variation in observed body-element concentration whereas river of capture explained very little variation. Element composition of downstream migrating post-spawn adults (i.e. kelts) and juvenile smolts were similar and the composition of these two life stages strongly differed from adults migrating upstream to spawn. Low variation within life stages and across populations suggests that S. salar may exert rheostatic control of their body-element composition. Additionally, observed differences in trace element concentration between adults and other life stages were probably driven by the high carbon concentration in adults because abundant elements, such as carbon, can strongly influence the observed concentrations of less abundant elements. Thus, understanding variation among individuals in trace elements composition requires the measurement of more abundant elements. Changes in element concentration with ontogeny have important consequences the role of fishes in ecosystem nutrient cycling and should receive further attention. © 2016 The Fisheries Society of the British Isles.

Characterisation of the LH2 spectral variants produced by the photosynthetic purple sulphur bacterium Allochromatium vinosum.

PubMed

Carey, Anne-Marie; Hacking, Kirsty; Picken, Nichola; Honkanen, Suvi; Kelly, Sharon; Niedzwiedzki, Dariusz M; Blankenship, Robert E; Shimizu, Yuuki; Wang-Otomo, Zheng-Yu; Cogdell, Richard J

2014-11-01

This study systematically investigated the different types of LH2 produced by Allochromatium (Alc.) vinosum, a photosynthetic purple sulphur bacterium, in response to variations in growth conditions. Three different spectral forms of LH2 were isolated and purified, the B800-820, B800-840 and B800-850 LH2 types, all of which exhibit an unusual split 800 peak in their low temperature absorption spectra. However, it is likely that more forms are also present. Relatively more B800-820 and B800-840 are produced under low light conditions, while relatively more B800-850 is produced under high light conditions. Polypeptide compositions of the three different LH2 types were determined by a combination of HPLC and TOF/MS. The B800-820, B800-840 and B800-850 LH2 types all have a heterogeneous polypeptide composition, containing multiple types of both α and β polypeptides, and differ in their precise polypeptide composition. They all have a mixed carotenoid composition, containing carotenoids of the spirilloxanthin series. In all cases the most abundant carotenoid is rhodopin; however, there is a shift towards carotenoids with a higher conjugation number in LH2 complexes produced under low light conditions. CD spectroscopy, together with the polypeptide analysis, demonstrates that these Alc. vinosum LH2 complexes are more closely related to the LH2 complex from Phs. molischianum than they are to the LH2 complexes from Rps. acidophila. Copyright © 2014. Published by Elsevier B.V.

The Effect of Geographic Units of Analysis on Measuring Geographic Variation in Medical Services Utilization.

PubMed

Kim, Agnus M; Park, Jong Heon; Kang, Sungchan; Hwang, Kyosang; Lee, Taesik; Kim, Yoon

2016-07-01

We aimed to evaluate the effect of geographic units of analysis on measuring geographic variation in medical services utilization. For this purpose, we compared geographic variations in the rates of eight major procedures in administrative units (districts) and new areal units organized based on the actual health care use of the population in Korea. To compare geographic variation in geographic units of analysis, we calculated the age-sex standardized rates of eight major procedures (coronary artery bypass graft surgery, percutaneous transluminal coronary angioplasty, surgery after hip fracture, knee-replacement surgery, caesarean section, hysterectomy, computed tomography scan, and magnetic resonance imaging scan) from the National Health Insurance database in Korea for the 2013 period. Using the coefficient of variation, the extremal quotient, and the systematic component of variation, we measured geographic variation for these eight procedures in districts and new areal units. Compared with districts, new areal units showed a reduction in geographic variation. Extremal quotients and inter-decile ratios for the eight procedures were lower in new areal units. While the coefficient of variation was lower for most procedures in new areal units, the pattern of change of the systematic component of variation between districts and new areal units differed among procedures. Geographic variation in medical service utilization could vary according to the geographic unit of analysis. To determine how geographic characteristics such as population size and number of geographic units affect geographic variation, further studies are needed.

Characterization of the chemical variation of feed coal and coal combustion products from a power plant utilizing low sulfur Powder River Basin coal

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

Affolter, R.H.; Brownfield, M.E.; Cathcart, J.D.

2000-07-01

The US Geological Survey and the University of Kentucky Center for Applied Energy Research, in collaboration with an Indiana utility, are studying a coal-fired power plant burning Powder River Basin coal. This investigation involves a systematic study of the chemical and mineralogical characteristics of feed coal and coal combustion products (CCPs) from a 1,300-megawatt (MW) power unit. The main goal of this study is to characterize the temporal chemical variability of the feed coal, fly ash, and bottom ash by looking at the major-, minor-, and trace-element compositions and their associations with the feed coal mineralogy. Emphasis is also placedmore » on the abundance and modes of occurrence of elements of potential environmental concern that may affect the utilization of these CCPs and coals.« less

Determination of highly protein bound drugs in plasma using high-performance liquid chromatography and column switching, exemplified by the retinoids.

PubMed

Wyss, R; Bucheli, F

1988-12-02

During method development for the determination of either isotretinoin, tretinoin and their 4-oxo-metabolites, or etretinate, acitretin and 13-cis-acitretin in plasma using high-performance liquid chromatography and column switching, recovery problems arose, when undiluted plasma samples were injected directly onto the precolumn. These recovery problems may be due to the strong binding of the retinoids to different plasma proteins. Measures to overcome this strong protein binding, such as variation of the injection solution composition and the purge mobile phase, were systematically investigated. Best recoveries were obtained by diluting of plasma with 9 mM sodium hydroxide-acetonitrile (8:2, v/v) and protein precipitation with ethanol for the isotretinoin and etretinate series, respectively, in combination with the use of a purge mobile phase containing ammonium acetate and 10-20% acetonitrile. Less effective was the use of a longer precolumn or heating of the precolumn.

Workshop on Oxygen in Asteroids and Meteorites

NASA Technical Reports Server (NTRS)

2005-01-01

Contents include the following: Constraints on the detection of solar nebula's oxidation state through asteroid observation. Oxidation/Reduction Processes in Primitive Achondrites. Low-Temperature Chemical Processing on Asteroids. On the Formation Location of Asteroids and Meteorites. The Spectral Properties of Angritic Basalts. Correlation Between Chemical and Oxygen Isotopic Compositions in Chondrites. Effect of In-Situ Aqueous Alteration on Thermal Model Heat Budgets. Oxidation-Reduction in Meteorites: The Case of High-Ni Irons. Ureilite Atmospherics: Coming up for Air on a Parent Body. High Temperature Effects Including Oxygen Fugacity, in Pre-Planetary and Planetary Meteorites and Asteroids. Oxygen Isotopic Variation of Asteroidal Materials. High-Temperature Chemical Processing on Asteroids: An Oxygen Isotope Perspective. Oxygen Isotopes and Origin of Opaque Assemblages from the Ningqiang Carbonaceous Chondrite. Water Distribution in the Asteroid Belt. Comparative Planetary Mineralogy: V Systematics in Planetary Pyroxenes and fo 2 Estimates for Basalts from Vesta.

Cosmic Chandlery with thermonuclear supernovae

DOE PAGES

Calder, Alan C.; Krueger, Brendan K.; Jackson, A. P.; ...

2017-05-30

Thermonuclear (Type Ia) supernovae are bright stellar explosions, the light curves of which can be calibrated to allow for use as "standard candles" for measuring cosmological distances. Contemporary research investigates how the brightness of an event may be influenced by properties of the progenitor system that follow from properties of the host galaxy such as composition and age. The goals are to better understand systematic effects and to assess the intrinsic scatter in the brightness, thereby reducing uncertainties in cosmological studies. We present the results from ensembles of simulations in the single-degenerate paradigm addressing the influence of age and metallicitymore » on the brightness of an event and compare our results to observed variations of brightness that correlate with properties of the host galaxy. As a result, we also present results from "hybrid" progenitor models that incorporate recent advances in stellar evolution.« less

Interobserver delineation variation in lung tumour stereotactic body radiotherapy

PubMed Central

Persson, G F; Nygaard, D E; Hollensen, C; Munck af Rosenschöld, P; Mouritsen, L S; Due, A K; Berthelsen, A K; Nyman, J; Markova, E; Roed, A P; Roed, H; Korreman, S; Specht, L

2012-01-01

Objectives In radiotherapy, delineation uncertainties are important as they contribute to systematic errors and can lead to geographical miss of the target. For margin computation, standard deviations (SDs) of all uncertainties must be included as SDs. The aim of this study was to quantify the interobserver delineation variation for stereotactic body radiotherapy (SBRT) of peripheral lung tumours using a cross-sectional study design. Methods 22 consecutive patients with 26 tumours were included. Positron emission tomography/CT scans were acquired for planning of SBRT. Three oncologists and three radiologists independently delineated the gross tumour volume. The interobserver variation was calculated as a mean of multiple SDs of distances to a reference contour, and calculated for the transversal plane (SDtrans) and craniocaudal (CC) direction (SDcc) separately. Concordance indexes and volume deviations were also calculated. Results Median tumour volume was 13.0 cm3, ranging from 0.3 to 60.4 cm3. The mean SDtrans was 0.15 cm (SD 0.08 cm) and the overall mean SDcc was 0.26 cm (SD 0.15 cm). Tumours with pleural contact had a significantly larger SDtrans than tumours surrounded by lung tissue. Conclusions The interobserver delineation variation was very small in this systematic cross-sectional analysis, although significantly larger in the CC direction than in the transversal plane, stressing that anisotropic margins should be applied. This study is the first to make a systematic cross-sectional analysis of delineation variation for peripheral lung tumours referred for SBRT, establishing the evidence that interobserver variation is very small for these tumours. PMID:22919015

Short communication: Variation in the composition and properties of Swedish raw milk for ultra-high-temperature processing.

PubMed

Karlsson, Maria A; Langton, Maud; Innings, Fredrik; Wikström, Malin; Lundh, Åse Sternesjö

2017-04-01

The composition and properties of raw milk are of great importance for the quality and shelf life of the final dairy product, especially in products with a long shelf life [e.g., ultra-high-temperature (UHT)-treated milk]. The objective of this study was to investigate the compositional variation in raw milk samples before processing at the dairy plant. Moreover, we wanted to investigate the effect of the UHT process on this variation (i.e., if the same variation could be observed in the corresponding UHT milk). The quality traits analyzed included detailed milk composition, counts of total and psychrotrophic bacteria, proteolytic activity, and color, as well as predictive measures of stability (i.e., ethanol stability and heat coagulating time). Samples of raw milk and the corresponding produced UHT milk were collected and analyzed on a monthly basis during 1 yr. Principal component analysis was used to identify months showing similarities and differences with respect to total variation. In contrast to previous studies, we observed only small variations between months and no clear effect of season for the raw milk. For the UHT milk, July and the winter months (December, January, and February) tended to separate from the other months. Quality traits showing significant variation were only to some extent identical in raw milk and UHT-processed milk. A better understanding of the natural variation in raw milk quality will provide opportunities to improve the shelf life of UHT-treated milk products. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Cassini UVIS Observations of the Io Plasma Torus. 3; Observations of Temporal and Azimuthal Variability

NASA Technical Reports Server (NTRS)

Steffl, A. J.; Delamere, P. A.; Bagenal, F.

2006-01-01

In this third paper in a series presenting observations by the Cassini Ultraviolet Imaging Spectrometer (UVIS) of the Io plasma torus, we show remarkable, though subtle, spatio-temporal variations in torus properties. The Io torus is found to exhibit significant, near sinusoidal variations in ion composition as a functions of azimuthal position. The azimuthal variation in composition is such that the mixing ratio of S II us strongly correlated with the mixing ratio of S III and the equatorial electron density and strongly anti-correlated with the mixing ratios of both S IV and O II and the equatorial electron temperature. Surprisingly, the azimuthal variation in ion composition is observed to have a period of 10.07 h -- 1.5% longer than the System III rotation period of Jupiter, yet 1.3% shorter than the System UV period defined by [Brown, M. E., 1995. J. Geophys. Res. 100, 21683-21696]. Although the amplitude of the azimuthal variation of S III and O II remained in the range of 2-5%, the amplitude of the S II and S IV compositional variation ranged between 5 and 25% during the UVIS observations. Furthermore, the amplitude of the azimuthal variations of S II and S IV appears to be modulated by its location in System III longitude, such that when the region of maximum S II mixing ration (minimum S IV mixing ratio) is aligned with a System III longitude of 200 deg +/-, the amplitude is a factor of 4 greater than when the variation is anti-aligned. This behavior can explain numerous, often apparently contradictory, observations of variations in the properties of the Io plasma torus with the System III and System IV coordinate systems.

Spatio-temporal variation in foodscapes modifies deer browsing impact on vegetation

Treesearch

Alejandro A. Royo; David W. Kramer; Karl V. Miller; Nathan P. Nibbelink; Susan L. Stout

2017-01-01

Context. Ungulate browsers often alter plant composition and reduce diversity in forests worldwide, yet our ability to predict browse impact on vegetation remains equivocal. Theory suggests, however, that ungulate distribution and foraging impacts are shaped by scale-dependent decisions based on variation in habitat composition and structure...

Genome-wide association study of Arabidopsis thaliana identifies determinants of natural variation in seed oil composition

USDA-ARS?s Scientific Manuscript database

The renewable source of highly reduced carbon provided by plant triacylglycerols fills an ever increasing demand for food, biodiesel and industrial chemicals. Each of these uses requires different compositions of fatty acid proportions in seed oils. Identifying the genes responsible for variation in...

Cryogenic Calcite: A Morphologic and Isotopic Analog to the ALH84001 Carbonates

NASA Technical Reports Server (NTRS)

Niles, P. B.; Leshin, L. A.; Socki, R. A.; Guan, Y.; Ming, D. W.; Gibson, E. K.

2004-01-01

Martian meteorite ALH84001 carbonates preserve large and variable microscale isotopic compositions, which in some way reflect their formation environment. These measurements show large variations (>20%) in the carbon and oxygen isotopic compositions of the carbonates on a 10-20 micron scale that are correlated with chemical composition. However, the utilization of these data sets for interpreting the formation conditions of the carbonates is complex due to lack of suitable terrestrial analogs and the difficulty of modeling under non-equilibrium conditions. Thus, the mechanisms and processes are largely unknown that create and preserve large microscale isotopic variations in carbonate minerals. Experimental tests of the possible environments and mechanisms that lead to large microscale isotopic variations can help address these concerns. One possible mechanism for creating large carbon isotopic variations in carbonates involves the freezing of water. Carbonates precipitate during extensive CO2 degassing that occurs during the freezing process as the fluid s decreasing volume drives CO2 out. This rapid CO2 degassing results in a kinetic isotopic fractionation where the CO2 gas has a much lighter isotopic composition causing an enrichment of 13C in the remaining dissolved bicarbonate. This study seeks to determine the suitability of cryogenically formed carbonates as analogs to ALH84001 carbonates. Specifically, our objective is to determine how accurately models using equilibrium fractionation factors approximate the isotopic compositions of cryogenically precipitated carbonates. This includes determining the accuracy of applying equilibrium fractionation factors during a kinetic process, and determining how isotopic variations in the fluid are preserved in microscale variations in the precipitated carbonates.

Between-Group Variation in Female Dispersal, Kin Composition of Groups, and Proximity Patterns in a Black-and-White Colobus Monkey (Colobus vellerosus)

PubMed Central

Wikberg, Eva C.; Sicotte, Pascale; Campos, Fernando A.; Ting, Nelson

2012-01-01

A growing body of evidence shows within-population variation in natal dispersal, but the effects of such variation on social relationships and the kin composition of groups remain poorly understood. We investigate the link between dispersal, the kin composition of groups, and proximity patterns in a population of black-and-white colobus (Colobus vellerosus) that shows variation in female dispersal. From 2006 to 2011, we collected behavioral data, demographic data, and fecal samples of 77 males and 92 females residing in eight groups at Boabeng-Fiema, Ghana. A combination of demographic data and a genetic network analysis showed that although philopatry was female-biased, only about half of the females resided in their natal groups. Only one group contained female-female dyads with higher average relatedness than randomly drawn animals of both sexes from the same group. Despite between-group variation in female dispersal and kin composition, female-female dyads in most of the study groups had higher proximity scores than randomly drawn dyads from the same group. We conclude that groups fall along a continuum from female dispersed, not kin-based, and not bonded to female philopatric, kin-based, and bonded. We found only partial support for the predicted link between dispersal, kin composition, and social relationships. In contrast to most mammals where the kin composition of groups is a good predictor of the quality of female-female relationships, this study provides further support for the notion that kinship is not necessary for the development and maintenance of social bonds in some gregarious species. PMID:23144951

Infants Are Sensitive to Within-Category Variation in Speech Perception

ERIC Educational Resources Information Center

McMurray, Bob; Aslin, Richard N.

2005-01-01

Previous research on speech perception in both adults and infants has supported the view that consonants are perceived categorically; that is, listeners are relatively insensitive to variation below the level of the phoneme. More recent work, on the other hand, has shown adults to be systematically sensitive to within category variation [McMurray,…

Seasonality of Oxygen isotope composition in cow (Bos taurus) hair and its model interpretation

NASA Astrophysics Data System (ADS)

Chen, Guo; Schnyder, Hans; Auerswald, Karl

2017-04-01

Oxygen isotopes in animal and human tissues are expected to be good recorders of geographical origin and migration histories based on the isotopic relationship between hair oxygen and annual precipitation and the well-known spatial pattern of oxygen isotope composition in meteoric water. However, seasonal variation of oxygen isotope composition may diminish the origin information in the tissues. Here the seasonality of oxygen isotope composition in tail hair was investigated in a domestic suckler cow (Bos taurus) that underwent different ambient conditions, physiological states, and keeping and feeding strategies during five years. A detailed mechanistic model involving in ambient conditions, soil properties and animal physiology was built to explain this variation. The measured oxygen isotope composition in hair was significantly related (p<0.05) to the isotope composition in meteoric water in a regression analysis. Modelling suggested that this relation was only partly derived from the direct influence of feed moisture. Ambient conditions (temperature, moisture) did not only influence the isotopic signal of precipitation but also affected the animal itself (drinking water demand, transcutaneous vapor etc.). The clear temporal variation thus resulted from complex interactions with multiple influences. The twofold influence of ambient conditions via the feed and via the animal itself is advantageous for tracing the geographic origin because the oxygen isotope composition is then less influenced by variations in moisture uptake; however, it is unfavorable for indicating the production system, e.g. to distinguish between milk produced from fresh grass or from silage.

Artifacts reduction in VIR/Dawn data.

PubMed

Carrozzo, F G; Raponi, A; De Sanctis, M C; Ammannito, E; Giardino, M; D'Aversa, E; Fonte, S; Tosi, F

2016-12-01

Remote sensing images are generally affected by different types of noise that degrade the quality of the spectral data (i.e., stripes and spikes). Hyperspectral images returned by a Visible and InfraRed (VIR) spectrometer onboard the NASA Dawn mission exhibit residual systematic artifacts. VIR is an imaging spectrometer coupling high spectral and spatial resolutions in the visible and infrared spectral domain (0.25-5.0 μm). VIR data present one type of noise that may mask or distort real features (i.e., spikes and stripes), which may lead to misinterpretation of the surface composition. This paper presents a technique for the minimization of artifacts in VIR data that include a new instrument response function combining ground and in-flight radiometric measurements, correction of spectral spikes, odd-even band effects, systematic vertical stripes, high-frequency noise, and comparison with ground telescopic spectra of Vesta and Ceres. We developed a correction of artifacts in a two steps process: creation of the artifacts matrix and application of the same matrix to the VIR dataset. In the approach presented here, a polynomial function is used to fit the high frequency variations. After applying these corrections, the resulting spectra show improvements of the quality of the data. The new calibrated data enhance the significance of results from the spectral analysis of Vesta and Ceres.

Joint inversion of shear wave travel time residuals and geoid and depth anomalies for long-wavelength variations in upper mantle temperature and composition along the Mid-Atlantic Ridge

NASA Technical Reports Server (NTRS)

Sheehan, Anne F.; Solomon, Sean C.

1991-01-01

Measurements were carried out for SS-S differential travel time residuals for nearly 500 paths crossing the northern Mid-Atlantic Ridge, assuming that the residuals are dominated by contributions from the upper mantle near the surface bounce point of the reflected phase SS. Results indicate that the SS-S travel time residuals decrease linearly with square root of age, to an age of 80-100 Ma, in general agreement with the plate cooling model. A joint inversion was formulated of travel time residuals and geoid and bathymetric anomalies for lateral variation in the upper mantle temperature and composition. The preferred inversion solutions were found to have variations in upper mantle temperature along the Mid-Atlantic Ridge of about 100 K. It was calculated that, for a constant bulk composition, such a temperature variation would produce about a 7-km variation in crustal thickness, larger than is generally observed.

Chemical variations in Yellowknife Bay formation sedimentary rocks analyzed by ChemCam on board the Curiosity rover on Mars

USGS Publications Warehouse

Mangold, Nicolas; Forni, Olivier; Dromart, G.; Stack, K.M.; Wiens, Roger C.; Gasnault, Olivier; Sumner, Dawn Y.; Nachon, Marion; Meslin, Pierre-Yves; Anderson, Ryan B.; Barraclough, Bruce; Bell, J.F.; Berger, G.; Blaney, D.L.; Bridges, J.C.; Calef, F.; Clark, Brian R.; Clegg, Samuel M.; Cousin, Agnes; Edgar, L.; Edgett, Kenneth S.; Ehlmann, B.L.; Fabre, Cecile; Fisk, M.; Grotzinger, John P.; Gupta, S.C.; Herkenhoff, Kenneth E.; Hurowitz, J.A.; Johnson, J. R.; Kah, Linda C.; Lanza, Nina L.; Lasue, Jeremie; Le Mouélic, S.; Lewin, Eric; Malin, Michael; McLennan, Scott M.; Maurice, S.; Melikechi, Noureddine; Mezzacappa, Alissa; Milliken, Ralph E.; Newsome, H.L.; Ollila, A.; Rowland, Scott K.; Sautter, Violaine; Schmidt, M.E.; Schroder, S.; D'Uston, C.; Vaniman, Dave; Williams, R.A.

2015-01-01

The Yellowknife Bay formation represents a ~5 m thick stratigraphic section of lithified fluvial and lacustrine sediments analyzed by the Curiosity rover in Gale crater, Mars. Previous works have mainly focused on the mudstones that were drilled by the rover at two locations. The present study focuses on the sedimentary rocks stratigraphically above the mudstones by studying their chemical variations in parallel with rock textures. Results show that differences in composition correlate with textures and both manifest subtle but significant variations through the stratigraphic column. Though the chemistry of the sediments does not vary much in the lower part of the stratigraphy, the variations in alkali elements indicate variations in the source material and/or physical sorting, as shown by the identification of alkali feldspars. The sandstones contain similar relative proportions of hydrogen to the mudstones below, suggesting the presence of hydrous minerals that may have contributed to their cementation. Slight variations in magnesium correlate with changes in textures suggesting that diagenesis through cementation and dissolution modified the initial rock composition and texture simultaneously. The upper part of the stratigraphy (~1 m thick) displays rocks with different compositions suggesting a strong change in the depositional system. The presence of float rocks with similar compositions found along the rover traverse suggests that some of these outcrops extend further away in the nearby hummocky plains.

Scaling up the Single Transducer Thickness-Independent Ultrasonic Imaging Method for Accurate Characterization of Microstructural Gradients in Monolithic and Composite Tubular Structures

NASA Technical Reports Server (NTRS)

Roth, Don J.; Carney, Dorothy V.; Baaklini, George Y.; Bodis, James R.; Rauser, Richard W.

1998-01-01

Ultrasonic velocity/time-of-flight imaging that uses back surface reflections to gauge volumetric material quality is highly suited for quantitative characterization of microstructural gradients including those due to pore fraction, density, fiber fraction, and chemical composition variations. However, a weakness of conventional pulse-echo ultrasonic velocity/time-of-flight imaging is that the image shows the effects of thickness as well as microstructural variations unless the part is uniformly thick. This limits this imaging method's usefulness in practical applications. Prior studies have described a pulse-echo time-of-flight-based ultrasonic imaging method that requires using a single transducer in combination with a reflector plate placed behind samples that eliminates the effect of thickness variation in the image. In those studies, this method was successful at isolating ultrasonic variations due to material microstructure in plate-like samples of silicon nitride, metal matrix composite, and polymer matrix composite. In this study, the method is engineered for inspection of more complex-shaped structures-those having (hollow) tubular/curved geometry. The experimental inspection technique and results are described as applied to (1) monolithic mullite ceramic and polymer matrix composite 'proof-of-concept' tubular structures that contain machined patches of various depths and (2) as-manufactured monolithic silicon nitride ceramic and silicon carbide/silicon carbide composite tubular structures that might be used in 'real world' applications.

Worldwide Impact of Warmer Seasons on the Incidence of Renal Colic and Kidney Stone Disease: Evidence from a Systematic Review of Literature.

PubMed

Geraghty, Robert M; Proietti, Silvia; Traxer, Olivier; Archer, Matthew; Somani, Bhaskar K

2017-08-01

Several studies have examined the link between temperature or monthly seasonal variations and urolithiasis. The majority of these studies have demonstrated a link between higher ambient monthly temperatures and the incidence of renal colic and kidney stone disease (KSD). However, a worldwide trend on this association has not been explored and we perform a systematic review to examine the effect of seasonal variations on renal colic and KSD. A systematic review of the literature for a 26-year period (1990-2017) was conducted on all studies reporting on the effect of seasonal variations and its link to KSD. Two reviewers independently extracted the data from each study, which were analyzed using SPSS version 24. A total of 59 studies were identified, and after screening, 13 were included in this review. The studies ranged in duration from 1 to 9 years (mean: 5.5 years) and included seasonal/monthly variations for proven stones or lithotripsy treatments or emergency department presentations with renal colic. Except for one study, there was a statistically significant association between higher monthly mean temperatures and the incidence of KSD-related events reported from the United Kingdom, South Korea, the United States, Saudi Arabia, Italy, Spain, Taiwan, Japan, and New Zealand. Worldwide trends on the incidence of renal colic and KSD seem be affected by seasonal variation favoring warmer months, with data suggesting that higher ambient temperature has an association with KSD.

Categorial Compositionality: A Category Theory Explanation for the Systematicity of Human Cognition

PubMed Central

Phillips, Steven; Wilson, William H.

2010-01-01

Classical and Connectionist theories of cognitive architecture seek to explain systematicity (i.e., the property of human cognition whereby cognitive capacity comes in groups of related behaviours) as a consequence of syntactically and functionally compositional representations, respectively. However, both theories depend on ad hoc assumptions to exclude specific instances of these forms of compositionality (e.g. grammars, networks) that do not account for systematicity. By analogy with the Ptolemaic (i.e. geocentric) theory of planetary motion, although either theory can be made to be consistent with the data, both nonetheless fail to fully explain it. Category theory, a branch of mathematics, provides an alternative explanation based on the formal concept of adjunction, which relates a pair of structure-preserving maps, called functors. A functor generalizes the notion of a map between representational states to include a map between state transformations (or processes). In a formal sense, systematicity is a necessary consequence of a higher-order theory of cognitive architecture, in contrast to the first-order theories derived from Classicism or Connectionism. Category theory offers a re-conceptualization for cognitive science, analogous to the one that Copernicus provided for astronomy, where representational states are no longer the center of the cognitive universe—replaced by the relationships between the maps that transform them. PMID:20661306

Categorial compositionality: a category theory explanation for the systematicity of human cognition.

PubMed

Phillips, Steven; Wilson, William H

2010-07-22

Classical and Connectionist theories of cognitive architecture seek to explain systematicity (i.e., the property of human cognition whereby cognitive capacity comes in groups of related behaviours) as a consequence of syntactically and functionally compositional representations, respectively. However, both theories depend on ad hoc assumptions to exclude specific instances of these forms of compositionality (e.g. grammars, networks) that do not account for systematicity. By analogy with the Ptolemaic (i.e. geocentric) theory of planetary motion, although either theory can be made to be consistent with the data, both nonetheless fail to fully explain it. Category theory, a branch of mathematics, provides an alternative explanation based on the formal concept of adjunction, which relates a pair of structure-preserving maps, called functors. A functor generalizes the notion of a map between representational states to include a map between state transformations (or processes). In a formal sense, systematicity is a necessary consequence of a higher-order theory of cognitive architecture, in contrast to the first-order theories derived from Classicism or Connectionism. Category theory offers a re-conceptualization for cognitive science, analogous to the one that Copernicus provided for astronomy, where representational states are no longer the center of the cognitive universe--replaced by the relationships between the maps that transform them.

Self-compensating design for reduction of timing and leakage sensitivity to systematic pattern dependent variation

NASA Astrophysics Data System (ADS)

Gupta, Puneet; Kahng, Andrew B.; Kim, Youngmin; Sylvester, Dennis

2006-03-01

Focus is one of the major sources of linewidth variation. CD variation caused by defocus is largely systematic after the layout is finished. In particular, dense lines "smile" through focus while isolated lines "frown" in typical Bossung plots. This well-defined systematic behavior of focus-dependent CD variation allows us to develop a self-compensating design methodology. In this work, we propose a novel design methodology that allows explicit compensation of focus-dependent CD variation, either within a cell (self-compensated cells) or across cells in a critical path (self-compensated design). By creating iso and dense variants for each library cell, we can achieve designs that are more robust to focus variation. Optimization with a mixture of iso and dense cell variants is possible both for area and leakage power, with the latter providing an interesting complement to existing leakage reduction techniques such as dual-Vth. We implement both heuristic and Mixed-Integer Linear Programming (MILP) solution methods to address this optimization, and experimentally compare their results. Our results indicate that designing with a self-compensated cell library incurs ~12% area penalty and ~6% leakage increase over original layouts while compensating for focus-dependent CD variation (i.e., the design meets timing constraints across a large range of focus variation). We observe ~27% area penalty and ~7% leakage increase at the worst-case defocus condition using only single-pitch cells. The area penalty of circuits after using either the heuristic or MILP optimization approach is reduced to ~3% while maintaining timing. We also apply our optimizations to leakage, which traditionally shows very large variability due to its exponential relationship with gate CD. We conclude that a mixed iso/dense library combined with a sensitivity-based optimization approach yields much better area/timing/leakage tradeoffs than using a self-compensated cell library alone. Self-compensated design shows an average of 25% leakage reduction at the worst defocus condition for the benchmark designs that we have studied.

A Review of Dendroctonus frontalis Zimmermann Systematics

Treesearch

Anthony I. Cognato

2011-01-01

The systematic history of the southern pine beetle, Dendroctonus frontalis Zimmermann, is reviewed. Morphological, biological, karyological, and molecular data clearly define and diagnose the species limits of D. frontalis. More complete phylogenetic analysis and characterization of population genetic variation will further clarify the evolutionary history of the D....

WE-AB-207B-03: A Computational Methodology for Determination of CTV-To-PTV Margins with Inter Fractional Shape Variations Based On a Statistical Point Distribution Model for Prostate Cancer Radiation Therapy

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

Shibayama, Y; Umezu, Y; Nakamura, Y

2016-06-15

Purpose: Our assumption was that interfractional shape variations of target volumes could not be negligible for determination of clinical target volume (CTV)-to-planning target volume (PTV) margins. The aim of this study was to investigate this assumption as a simulation study by developing a computational framework of CTV-to-PTV margins with taking the interfractional shape variations into account based on point distribution model (PDM) Methods: The systematic and random errors for interfractional shape variations and translations of target volumes were evaluated for four types of CTV regions (only a prostate, a prostate plus proximal 1-cm seminal vesicles, a prostate plus proximal 2-cmmore » seminal vesicles, and a prostate plus whole seminal vesicles). The CTV regions were delineated depending on prostate cancer risk groups on planning computed tomography (CT) and cone beam CT (CBCT) images of 73 fractions of 10 patients. The random and systematic errors for shape variations of CTV regions were derived from PDMs of CTV surfaces for all fractions of each patient. Systematic errors of shape variations of CTV regions were derived by comparing PDMs between planning CTV surfaces and average CTV surfaces. Finally, anisotropic CTV-to-PTV margins with shape variations in 6 directions (anterior, posterior, superior, inferior, right, and left) were computed by using a van Herk margin formula. Results: Differences between CTV-to-PTV margins with and without shape variations ranged from 0.7 to 1.7 mm in anterior direction, 1.0 to 2.8 mm in posterior direction, 0.8 to 2.8 mm in superior direction, 0.6 to 1.6 mm in inferior direction, 1.4 to 4.4 mm in right direction, and 1.3 to 5.2 mm in left direction. Conclusion: More than 1.0 mm additional margins were needed at least in 3 directions to guarantee CTV coverage due to shape variations. Therefore, shape variations should be taken into account for the determination of CTV-to-PTV margins.« less

An Overview of the Southern Mariana Subduction Factory: Arc, Cross-Chains, and Back-Arc Basin

NASA Astrophysics Data System (ADS)

Stern, R. J.; Hargrove, U. S.; Leybourne, M. I.; Pearce, J. A.; Bloomer, S. H.

2002-12-01

The Mariana arc system south of 18°N provides 3 opportunities to study the magmatic outputs of the IBM Subduction Factory: 1) Along the Magmatic arc; 2) Across arc cross-chains; and 3) Along the back-arc basin spreading axis. In spite of being located near population centers of Guam and Saipan, this is a relatively poorly known part of the arc system. There is a clear break in the trend and morphology of the magmatic arc west of the144°E fault and slab tear, and we surveyed and sampled the region north and east of this during the Cook 7 expedition in March-April 2001. Systematic morphologic covariations are observed along the arc and backarc basin magmatic systems, with the shallower ridge depths adjacent to more magmatically-robust arc segments. Our preliminary results reveal a compositional discontinuity in back-arc basin basalts (BABB) south of a bathymetric break near 15°30'N, with BABB in shallower segments to the north having a strong subduction component (higher Ba/Nb, Rb, Zr, etc.) and deeper regions to the south being more MORB-like. This is close to the morphological break along the magmatic front, with larger (>10E11 m3) edifices of the Central Island Province north of 16°N and smaller, entirely submarine volcanoes to the south, implying a more robust magmatic budget in the north; a similar variations are observed for cross-chain volcanoes, with smaller ones associated with the smaller, southern arc volcanoes and larger ones associated with the larger arc volcanoes of the Central Island Province. In contrast to the back-arc basin spreading axis, no systematic compositional variations are observed along or across the arc. Arc and cross-chains comprise a coherent, low- to medium-K, dominantly tholeiitic suite. REE patterns show moderate LREE-enrichment, with chondrite-normalized La/Yb = 1.5-2. Rear-arc volcanoes sometimes are slightly less fractionated, slightly more potassic, and slightly more LREE-enriched, but these are second order differences. The strong increase in K and LREE enrichment and decrease in fluid-mobile elements observed for the Kasuga cross-chain to the north is not observed in the southern cross-chains.

Growth and Characterization of Chalcogenide Alloy Nanowires with Controlled Spatial Composition Variation for Optoelectronic Applications

NASA Astrophysics Data System (ADS)

Nichols, Patricia

The energy band gap of a semiconductor material critically influences the operating wavelength of an optoelectronic device. Realization of any desired band gap, or even spatially graded band gaps, is important for applications such as lasers, light-emitting diodes (LEDs), solar cells, and detectors. Compared to thin films, nanowires offer greater flexibility for achieving a variety of alloy compositions. Furthermore, the nanowire geometry permits simultaneous incorporation of a wide range of compositions on a single substrate. Such controllable alloy composition variation can be realized either within an individual nanowire or between distinct nanowires across a substrate. This dissertation explores the control of spatial composition variation in ternary alloy nanowires. Nanowires were grown by the vapor-liquid-solid (VLS) mechanism using chemical vapor deposition (CVD). The gas-phase supersaturation was considered in order to optimize the deposition morphology. Composition and structure were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), and x-ray diffraction (XRD). Optical properties were investigated through photoluminescence (PL) measurements. The chalcogenides selected as alloy endpoints were lead sulfide (PbS), cadmium sulfide (CdS), and cadmium selenide (CdSe). Three growth modes of PbS were identified, which included contributions from spontaneously generated catalyst. The resulting wires were found capable of lasing with wavelengths over 4000 nm, representing the longest known wavelength from a sub-wavelength wire. For CdxPb1-xS nanowires, it was established that the cooling process significantly affects the alloy composition and structure. Quenching was critical to retain metastable alloys with x up to 0.14, representing a new composition in nanowire form. Alternatively, gradual cooling caused phase segregation, which created heterostructures with light emission in both the visible and mid-infrared regimes. The CdSSe alloy system was fully explored for spatial composition variation. CdSxSe1-x nanowires were grown with composition variation across the substrate. Subsequent contact printing preserved the designed composition gradient and led to the demonstration of a variable wavelength photodetector device. CdSSe axial heterostructure nanowires were also achieved. The growth process involved many variables, including a deliberate and controllable change in substrate temperature. As a result, both red and green light emission was detected from single nanowires.

Land surface phenology as a coarse-filter indicator of disturbance and climatic effects across the coast redwood range

Treesearch

Steven P. Norman; William W. Hargrove

2012-01-01

Satellite-based measurements provide a systematic measure of the seasonal fluctuations and general condition of forest vegetation, including that of the coast redwood region. Year-toyear variation in greenness may be caused by gradual disturbances, successional recovery or climatic variation, while within-year variation reflects disturbance events and the response of...

Isotopic evidence for the infiltration of mantle and metamorphic CO2-H2O fluids from below in faulted rocks from the San Andreas Fault System

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

Pili, E.; Kennedy, B.M.; Conrad, M.E.

To characterize the origin of the fluids involved in the San Andreas Fault (SAF) system, we carried out an isotope study of exhumed faulted rocks from deformation zones, vein fillings and their hosts and the fluid inclusions associated with these materials. Samples were collected from segments along the SAF system selected to provide a depth profile from upper to lower crust. In all, 75 samples from various structures and lithologies from 13 localities were analyzed for noble gas, carbon, and oxygen isotope compositions. Fluid inclusions exhibit helium isotope ratios ({sup 3}He/{sup 4}He) of 0.1-2.5 times the ratio in air, indicatingmore » that past fluids percolating through the SAF system contained mantle helium contributions of at least 35%, similar to what has been measured in present-day ground waters associated with the fault (Kennedy et al., 1997). Calcite is the predominant vein mineral and is a common accessory mineral in deformation zones. A systematic variation of C- and O-isotope compositions of carbonates from veins, deformation zones and their hosts suggests percolation by external fluids of similar compositions and origin with the amount of fluid infiltration increasing from host rocks to vein to deformation zones. The isotopic trend observed for carbonates in veins and deformation zones follows that shown by carbonates in host limestones, marbles, and other host rocks, increasing with increasing contribution of deep metamorphic crustal volatiles. At each crustal level, the composition of the infiltrating fluids is thus buffered by deeper metamorphic sources. A negative correlation between calcite {delta}{sup 13}C and fluid inclusion {sup 3}He/{sup 4}He is consistent with a mantle origin for a fraction of the infiltrating CO{sub 2}. Noble gas and stable isotope systematics show consistent evidence for the involvement of mantle-derived fluids combined with infiltration of deep metamorphic H{sub 2}O and CO{sub 2} in faulting, supporting the involvement of deep fluids percolating through and perhaps weakening the fault zone. There is no clear evidence for a significant contribution from meteoric water, except for overprinting related to late weathering.« less

Computational Reduction of Specimen Noise to Enable Improved Thermography Characterization of Flaws in Graphite Polymer Composites

NASA Technical Reports Server (NTRS)

Winfree, William P.; Howell, Patricia A.; Zalameda, Joseph N.

2014-01-01

Flaw detection and characterization with thermographic techniques in graphite polymer composites are often limited by localized variations in the thermographic response. Variations in properties such as acceptable porosity, fiber volume content and surface polymer thickness result in variations in the thermal response that in general cause significant variations in the initial thermal response. These result in a "noise" floor that increases the difficulty of detecting and characterizing deeper flaws. A method is presented for computationally removing a significant amount of the "noise" from near surface porosity by diffusing the early time response, then subtracting it from subsequent responses. Simulations of the thermal response of a composite are utilized in defining the limitations of the technique. This method for reducing the data is shown to give considerable improvement characterizing both the size and depth of damage. Examples are shown for data acquired on specimens with fabricated delaminations and impact damage.

Computational reduction of specimen noise to enable improved thermography characterization of flaws in graphite polymer composites

NASA Astrophysics Data System (ADS)

Winfree, William P.; Howell, Patricia A.; Zalameda, Joseph N.

2014-05-01

Flaw detection and characterization with thermographic techniques in graphite polymer composites are often limited by localized variations in the thermographic response. Variations in properties such as acceptable porosity, fiber volume content and surface polymer thickness result in variations in the thermal response that in general cause significant variations in the initial thermal response. These result in a "noise" floor that increases the difficulty of detecting and characterizing deeper flaws. A method is presented for computationally removing a significant amount of the "noise" from near surface porosity by diffusing the early time response, then subtracting it from subsequent responses. Simulations of the thermal response of a composite are utilized in defining the limitations of the technique. This method for reducing the data is shown to give considerable improvement characterizing both the size and depth of damage. Examples are shown for data acquired on specimens with fabricated delaminations and impact damage.

Effect of ‘A’-site non stoichiometry in strontium doped lanthanum ferrite based solid oxide fuel cell cathodes

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

Banerjee, Koyel; Mukhopadhyay, Jayanta, E-mail: jayanta_mu@cgcri.res.in; Barman, Madhurima

2015-12-15

Highlights: • La{sub 1−x}Sr{sub x}Co{sub y}Fe{sub 1−y}O{sub 3−δ}, x = 0.4; y = 0.2 system varying La-site (0.6–0.54) are studied. • Combustion synthesis technique is used to prepare the powder samples. • Highest electrical conductivity observed with largest A-site deficit composition. • Lowest cathode polarization is found with the same composition (0.02 Ω cm{sup 2}). • Composition with largest A-site deficiency exhibits best performance (2.84 A cm{sup −2}). - Abstract: Effect of A-site non-stoichiometry in strontium doped lanthanum cobalt ferrite (La{sub 1−x}Sr{sub x}Co{sub y}Fe{sub 1−y}O{sub 3−δ}, x = 0.4; y = 0.2) is studied in a systematic manner with variationmore » of ‘A’ site stoichiometry from 1 to 0.94. The perovskite based cathode compositions are synthesized by combustion synthesis. Powder characterizations reveal rhombohedral crystal structure with crystallite size ranging from 29 to 34 nm with minimum lattice spacing of 0.271 nm. Detailed sintering studies along with total DC electrical conductivities are evaluated in the bulk form with variation of sintering temperatures. The electrode polarizations are measured in the symmetric cell configuration by impedance spectroscopy which is found to be the lowest (0.02 Ω cm{sup 2} at 800 °C) for cathode having highest degree of ‘A’-site deficiency. The same cathode composition exhibits a current density of 2.84 A cm{sup −2} (at 0.7 V, 800 °C) in anode-supported single cell. An attempt has been made to correlate the trend of electrical behaviour with increasing ‘A’-site deficiency for such cathode compositions.« less

Inferred cation reordering in natural titanomagnetites with implications for Curie temperature and other magnetic properties (Invited)

NASA Astrophysics Data System (ADS)

Bowles, J. A.; Jackson, M. J.; Berquo, T. S.; Solheid, P.; Lappe, S. L.; Gee, J. S.

2013-12-01

We will present the results of recent work demonstrating that some natural titanomagnetites of common composition undergo cation reordering on laboratory timescales and at temperatures just above or below the Curie temperature (TC). This cation reordering produces changes in Curie temperature that have important implications for paleomagnetic studies and our understanding of remanence acquisition when TC is a function of prior thermal history. The bulk composition of the titanomagnetites (Fe3-xTixO4) varies between approximately 0.2 < x < 0.4, with moderate degrees of Mg and Al substitution. This composition is extremely common in rocks of andesitic, dacitic, and rhyolitic composition, as well as in some basalts. Samples were annealed for 10-1 to 103 hr at 350-425°C, producing large and reversible changes in TC (up to 150°C) that are roughly linear with log(anneal time). By ruling out oxidation/reduction and compositional unmixing, we interpret the variations in TC as arising from the re-distribution of ferric and ferrous iron cations between the octahedral and tetrahedral sites. Mössbauer spectroscopy supports this interpretation. Unlike pure titanomagnetite, the kinetics of the reordering process in these Mg- and Al-substituted natural titanomagnetites are apparently slow enough that intermediate degrees of ordering can be preserved by rapid quenching. The magnitude of the variation in TC produced by annealing at moderate temperatures correlates most strongly with Mg and Ti content and weakly with Al content. While strong variations are observed in TC, no detectible variation is found in saturation magnetization, and blocking temperature variations only weakly correlate with TC variation.

Regional variations in the diversity and predicted metabolic potential of benthic prokaryotes in coastal northern Zhejiang, East China Sea

PubMed Central

Wang, Kai; Ye, Xiansen; Zhang, Huajun; Chen, Heping; Zhang, Demin; Liu, Lian

2016-01-01

Knowledge about the drivers of benthic prokaryotic diversity and metabolic potential in interconnected coastal sediments at regional scales is limited. We collected surface sediments across six zones covering ~200 km in coastal northern Zhejiang, East China Sea and combined 16 S rRNA gene sequencing, community-level metabolic prediction, and sediment physicochemical measurements to investigate variations in prokaryotic diversity and metabolic gene composition with geographic distance and under local environmental conditions. Geographic distance was the most influential factor in prokaryotic β-diversity compared with major environmental drivers, including temperature, sediment texture, acid-volatile sulfide, and water depth, but a large unexplained variation in community composition suggested the potential effects of unmeasured abiotic/biotic factors and stochastic processes. Moreover, prokaryotic assemblages showed a biogeographic provincialism across the zones. The predicted metabolic gene composition similarly shifted as taxonomic composition did. Acid-volatile sulfide was strongly correlated with variation in metabolic gene composition. The enrichments in the relative abundance of sulfate-reducing bacteria and genes relevant with dissimilatory sulfate reduction were observed and predicted, respectively, in the Yushan area. These results provide insights into the relative importance of geographic distance and environmental condition in driving benthic prokaryotic diversity in coastal areas and predict specific biogeochemically-relevant genes for future studies. PMID:27917954

The prevalence of stillbirths: a systematic review

PubMed Central

Say, Lale; Donner, Allan; Gülmezoglu, A Metin; Taljaard, Monica; Piaggio, Gilda

2006-01-01

Background Stillbirth rate is an important indicator of access to and quality of antenatal and delivery care. Obtaining overall estimates across various regions of the world is not straightforward due to variation in definitions, data collection methods and reporting. Methods We conducted a systematic review of a range of pregnancy-related conditions including stillbirths and performed meta-analysis of the subset of studies reporting stillbirth rates. We examined variation across rates and used meta-regression techniques to explain observed variation. Results We identified 389 articles on stillbirth prevalence among the 2580 included in the systematic review. We included 70 providing 80 data sets from 50 countries in the meta-analysis. Pooled prevalence rates show variation across various subgroup categories. Rates per 100 births are higher in studies conducted in less developed country settings as compared to more developed (1.17 versus 0.50), of inadequate quality as compared to adequate (1.12 versus 0.66), using sub-national sample as compared to national (1.38 versus 0.68), reporting all stillbirths as compared to late stillbirths (0.95 versus 0.63), published in non-English as compared to English (0.91 versus 0.59) and as journal articles as compared to non-journal (1.37 versus 0.67). The results of the meta-regression show the significance of two predictor variables – development status of the setting and study quality – on stillbirth prevalence. Conclusion Stillbirth prevalence at the community level is typically less than 1% in more developed parts of the world and could exceed 3% in less developed regions. Regular reviews of stillbirth rates in appropriately designed and reported studies are useful in monitoring the adequacy of care. Systematic reviews of prevalence studies are helpful in explaining sources of variation across rates. Exploring these methodological issues will lead to improved standards for assessing the burden of reproductive ill-health. PMID:16401351

Variations in outcomes by residential location for women with breast cancer: a systematic review

PubMed Central

Dasgupta, Paramita; Youlden, Danny R; Garvey, Gail; Aitken, Joanne F; Wallington, Isabella; Chynoweth, Jennifer; Zorbas, Helen; Youl, Philippa H

2018-01-01

Objectives To systematically assess the evidence for variations in outcomes at each step along the breast cancer continuum of care for Australian women by residential location. Design Systematic review. Methods Systematic searches of peer-reviewed articles in English published from 1 January 1990 to 24 November 2017 using PubMed, EMBASE, CINAHL and Informit databases. Inclusion criteria were: population was adult female patients with breast cancer; Australian setting; outcome measure was survival, patient or tumour characteristics, screening rates or frequencies, clinical management, patterns of initial care or post-treatment follow-up with analysis by residential location or studies involving non-metropolitan women only. Included studies were critically appraised using a modified Newcastle–Ottawa Scale. Results Seventy-four quantitative studies met the inclusion criteria. Around 59% were considered high quality, 34% moderate and 7% low. No eligible studies examining treatment choices or post-treatment follow-up were identified. Non-metropolitan women consistently had poorer survival, with most of this differential being attributed to more advanced disease at diagnosis, treatment-related factors and socioeconomic disadvantage. Compared with metropolitan women, non-metropolitan women were more likely to live in disadvantaged areas and had differing clinical management and patterns of care. However, findings regarding geographical variations in tumour characteristics or diagnostic outcomes were inconsistent. Conclusions A general pattern of poorer survival and variations in clinical management for Australian female patients with breast cancer from non-metropolitan areas was evident. However, the wide variability in data sources, measures, study quality, time periods and geographical classification made direct comparisons across studies challenging. The review highlighted the need to promote standardisation of geographical classifications and increased comparability of data systems. It also identified key gaps in the existing literature including a lack of studies on advanced breast cancer, geographical variations in treatment choices from the perspective of patients and post-treatment follow-up. PMID:29706597

Ward's area location, physical activity, and body composition in 8- and 9-year-old boys and girls.

PubMed

Cardadeiro, Graça; Baptista, Fátima; Zymbal, Vera; Rodrigues, Luís A; Sardinha, Luís B

2010-11-01

Bone strength is the result of its material composition and structural design, particularly bone mass distribution. The purpose of this study was to analyze femoral neck bone mass distribution by Ward's area location and its relationship with physical activity (PA) and body composition in children 8 and 9 years of age. The proximal femur shape was defined by geometric morphometric analysis in 88 participants (48 boys and 40 girls). Using dual-energy X-ray absorptiometry (DXA) images, 18 landmarks were digitized to define the proximal femur shape and to identify Ward's area position. Body weight, lean and fat mass, and bone mineral were assessed by DXA, PA by accelerometry, and bone age by the Tanner-Whitehouse III method. Warps analysis with Thin-Plate Spline software showed that the first axis explained 63% of proximal femur shape variation in boys and 58% in girls. Most of this variation was associated with differences in Ward's area location, from the central zone to the superior aspect of the femoral neck in both genders. Regression analysis demonstrated that body composition explained 4% to 7% of the proximal femur shape variation in girls. In boys, body composition variables explained a similar amount of variance, but moderate plus vigorous PA (MVPA) also accounted for 6% of proximal femur shape variation. In conclusion, proximal femur shape variation in children ages 8 and 9 was due mainly to differences in Ward's area position determined, in part, by body composition in both genders and by MVPA in boys. These variables were positively associated with a central Ward's area and thus with a more balanced femoral neck bone mass distribution. © 2010 American Society for Bone and Mineral Research.

A Holistic Landscape Description Reveals That Landscape Configuration Changes More over Time than Composition: Implications for Landscape Ecology Studies.

PubMed

Mimet, Anne; Pellissier, Vincent; Houet, Thomas; Julliard, Romain; Simon, Laurent

2016-01-01

Space-for-time substitution-that is, the assumption that spatial variations of a system can explain and predict the effect of temporal variations-is widely used in ecology. However, it is questionable whether it can validly be used to explain changes in biodiversity over time in response to land-cover changes. Here, we hypothesize that different temporal vs spatial trajectories of landscape composition and configuration may limit space-for-time substitution in landscape ecology. Land-cover conversion changes not just the surface areas given over to particular types of land cover, but also affects isolation, patch size and heterogeneity. This means that a small change in land cover over time may have only minor repercussions on landscape composition but potentially major consequences for landscape configuration. Using land-cover maps of the Paris region for 1982 and 2003, we made a holistic description of the landscape disentangling landscape composition from configuration. After controlling for spatial variations, we analyzed and compared the amplitudes of changes in landscape composition and configuration over time. For comparable spatial variations, landscape configuration varied more than twice as much as composition over time. Temporal changes in composition and configuration were not always spatially matched. The fact that landscape composition and configuration do not vary equally in space and time calls into question the use of space-for-time substitution in landscape ecology studies. The instability of landscapes over time appears to be attributable to configurational changes in the main. This may go some way to explaining why the landscape variables that account for changes over time in biodiversity are not the same ones that account for the spatial distribution of biodiversity.

Systematic variations of argon diffusion in feldspars and implications for thermochronometry

DOE PAGES

Cassata, William S.; Renne, Paul R.

2013-03-07

Coupled information about the time-dependent production and temperature-dependent diffusion of radiogenic argon in feldspars can be used to constrain the thermal evolution attending a host of Earth and planetary processes. To better assess the accuracy of thermal models, an understanding of the mechanisms and pathways by which argon diffuses in feldspars is desirable. Here we present step-heating Ar diffusion experiments conducted on feldspars with diverse compositions, structural states, and microstructural characteristics. The experiments reveal systematic variations in diffusive behavior that appear closely related to these variables, with apparent closure temperatures for 0.1–1 mm grains of ~200–400 °C (assuming a 10more » °C/Ma cooling rate). Given such variability, there is no broadly applicable set of diffusion parameters that can be utilized in feldspar thermal modeling; sample-specific data are required. Diffusion experiments conducted on oriented cleavage flakes do not reveal directionally-dependent diffusive anisotropy to within the resolution limits of our approach (approximately a factor of 2). Additional experiments aimed at constraining the physical significance of the diffusion domain are presented and indicate that unaltered feldspar crystals with or without coherent exsolution lamellae diffuse at the grain-scale, whereas feldspars containing hydrothermal alteration and/or incoherent sub-grain intergrowths do not. Arrhenius plots for argon diffusion in plagioclase and alkali feldspars appear to reflect a confluence of intrinsic diffusion kinetics and structural transitions that occur during incremental heating experiments. These structural transitions, along with sub-grain domain size variations, cause deviations from linearity (i.e., upward and downward curvature) on Arrhenius plots. An atomistic model for Arrhenius behavior is proposed that incorporates the variable lattice deformations of different feldspars in response to heating and compression. Furthermore, the resulting implications for accurately extrapolating laboratory-derived diffusion parameters to natural settings and over geologic time are discussed. We find that considerable inaccuracies may exist in published thermal histories obtained using multiple diffusion domain (MDD) models fit to Arrhenius plots for exsolved alkali feldspar, where the inferred Ar partial retention zones may be spuriously hot.« less

Continuous Fiber Ceramic Composites

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

Fareed, Ali; Craig, Phillip A.

2002-09-01

Fiber-reinforced ceramic composites demonstrate the high-temperature stability of ceramics--with an increased fracture toughness resulting from the fiber reinforcement of the composite. The material optimization performed under the continuous fiber ceramic composites (CFCC) included a series of systematic optimizations. The overall goals were to define the processing window, to increase the robustinous of the process, to increase process yield while reducing costs, and to define the complexity of parts that could be fabricated.

The role of lipid composition for insertion and stabilization of amino acids in membranes

NASA Astrophysics Data System (ADS)

Johansson, Anna C. V.; Lindahl, Erik

2009-05-01

While most membrane protein helices are clearly hydrophobic, recent experiments have indicated that it is possible to insert marginally hydrophobic helices into bilayers and have suggested apparent in vivo free energies of insertion for charged residues that are low, e.g., a few kcals for arginine. In contrast, a number of biophysical simulation studies have predicted that the bilayer interior is close to a pure hydrophobic environment with large penalties for hydrophilic amino acids—and yet the experimental scales do significantly better at predicting actual membrane proteins from sequence. Here, we have systematically studied the dependence of the free energy profiles on lipid properties, including tail length, saturation, headgroup hydrogen bond strength, and charge, both to see to whether the in vivo insertion can be explained in whole or part from lipid composition of the endoplasmic reticulum (ER) membranes, and if the solvation properties can help interpret how protein function depends on the lipids. We find that lipid charge is important to stabilize charged amino acids inside the bilayer (with implications, e.g., for ion channels), that thicker bilayers have higher solvation costs for hydrophilic side chains, and that headgroup hydrogen bond strength determines how adaptive the lipids are as a hydrophobic/hydrophilic solvent. None of the different free energy profiles are even close to the low apparent in vivo insertion cost, which suggests that regardless of the specific ER membrane composition the current experimental results cannot be explained by normal lipid-type variation.

Natural habitats matter: Determinants of spatial pattern in the composition of animal assemblages of the Czech Republic

NASA Astrophysics Data System (ADS)

Divíšek, Jan; Zelený, David; Culek, Martin; Št'astný, Karel

2014-08-01

Studies that explore species-environment relationships at a broad scale are usually limited by the availability of sufficient habitat description, which is often too coarse to differentiate natural habitat patches. Therefore, it is not well understood how the distribution of natural habitats affects broad-scale patterns in the distribution of animal species. In this study, we evaluate the role of field-mapped natural habitats, land-cover types derived from remote sensing and climate on the composition of assemblages of five distinct animal groups, namely non-volant mammals, birds, reptiles, amphibians and butterflies native to the Czech Republic. First, we used variation partitioning based on redundancy analysis to evaluate the extent to which the environmental variables and their spatial structure might underlie the observed spatial patterns in the composition of animal assemblages. Second, we partitioned variations explained by climate, natural habitats and land-cover to compare their relative importance. Finally, we tested the independent effects of each variable in order to evaluate the significance of their contributions to the environmental model. Our results showed that spatial patterns in the composition of assemblages of almost all the considered animal groups may be ascribed mostly to variations in the environment. Although the shared effects of climatic variables, natural habitats and land-cover types explained the largest proportion of variation in each animal group, the variation explained purely by natural habitats was always higher than the variation explained purely by climate or land-cover. We conclude that most spatial variation in the composition of assemblages of almost all animal groups probably arises from biological processes operating within a spatially structured environment and suggest that natural habitats are important to explain observed patterns because they often perform better than habitat descriptions based on remote sensing. This underlines the value of using appropriate habitat data, for which high-resolution and large-area field-mapping projects are necessary.

Genomic characteristics of cattle copy number variations

USDA-ARS?s Scientific Manuscript database

We performed a systematic analysis of cattle copy number variations (CNVs) using the Bovine HapMap SNP genotyping data, including 539 animals of 21 modern cattle breeds and 6 outgroups. After correcting genomic waves and considering the trio information, we identified 682 candidate CNV regions (CNVR...

Continuity and Variation in Chinese Patterns of Socialization.

ERIC Educational Resources Information Center

Ho, David Y. F.

1989-01-01

Reviews literature on Chinese patterns of socialization. Discusses methodological issues with respect to continuity versus change through time, and variation across geographical locations, systematically considering variables of gender, age, and social class. Concludes that departures from traditional pattern in different locations are evident,…

Statistical process control and verifying positional accuracy of a cobra motion couch using step-wedge quality assurance tool.

PubMed

Binny, Diana; Lancaster, Craig M; Trapp, Jamie V; Crowe, Scott B

2017-09-01

This study utilizes process control techniques to identify action limits for TomoTherapy couch positioning quality assurance tests. A test was introduced to monitor accuracy of the applied couch offset detection in the TomoTherapy Hi-Art treatment system using the TQA "Step-Wedge Helical" module and MVCT detector. Individual X-charts, process capability (cp), probability (P), and acceptability (cpk) indices were used to monitor a 4-year couch IEC offset data to detect systematic and random errors in the couch positional accuracy for different action levels. Process capability tests were also performed on the retrospective data to define tolerances based on user-specified levels. A second study was carried out whereby physical couch offsets were applied using the TQA module and the MVCT detector was used to detect the observed variations. Random and systematic variations were observed for the SPC-based upper and lower control limits, and investigations were carried out to maintain the ongoing stability of the process for a 4-year and a three-monthly period. Local trend analysis showed mean variations up to ±0.5 mm in the three-monthly analysis period for all IEC offset measurements. Variations were also observed in the detected versus applied offsets using the MVCT detector in the second study largely in the vertical direction, and actions were taken to remediate this error. Based on the results, it was recommended that imaging shifts in each coordinate direction be only applied after assessing the machine for applied versus detected test results using the step helical module. User-specified tolerance levels of at least ±2 mm were recommended for a test frequency of once every 3 months to improve couch positional accuracy. SPC enables detection of systematic variations prior to reaching machine tolerance levels. Couch encoding system recalibrations reduced variations to user-specified levels and a monitoring period of 3 months using SPC facilitated in detecting systematic and random variations. SPC analysis for couch positional accuracy enabled greater control in the identification of errors, thereby increasing confidence levels in daily treatment setups. © 2017 Royal Brisbane and Women's Hospital, Metro North Hospital and Health Service. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

The Redshift Evolution of Rest-UV Spectroscopic Properties in Lyman-break Galaxies at z ∼ 2–4

NASA Astrophysics Data System (ADS)

Du, Xinnan; Shapley, Alice E.; Reddy, Naveen A.; Jones, Tucker; Stark, Daniel P.; Steidel, Charles C.; Strom, Allison L.; Rudie, Gwen C.; Erb, Dawn K.; Ellis, Richard S.; Pettini, Max

2018-06-01

We present the first comprehensive evolutionary analysis of the rest-frame UV spectroscopic properties of star-forming galaxies at z ∼ 2–4. We match samples at different redshifts in UV luminosity and stellar mass, and perform systematic measurements of spectral features and stellar population modeling. By creating composite spectra grouped according to Lyα equivalent width (EW) and various galaxy properties, we study the evolutionary trends among Lyα, low- and high-ionization interstellar (LIS and HIS) absorption features, and integrated galaxy properties. We also examine the redshift evolution of Lyα and LIS absorption kinematics, and fine-structure emission EWs. The connections among the strengths of Lyα, LIS lines, and dust extinction are redshift independent, as is the decoupling of the Lyα and HIS line strengths, and the bulk outflow kinematics as traced by the LIS lines. Stronger Lyα emission is observed at higher redshift at fixed UV luminosity, stellar mass, SFR, and age. Much of this variation in the average Lyα strength with redshift, and the variation in Lyα strength at fixed redshift, can be explained in terms of variations in the neutral gas covering fraction and/or dust content in the ISM and CGM. However, based on the connection between Lyα and C III] emission strengths, we additionally find evidence for variations in the intrinsic production rate of Lyα photons at the highest Lyα EWs. The challenge now is to understand the observed evolution of the neutral gas covering fraction and dust extinction within a coherent model for galaxy formation, and make robust predictions for the escape of ionizing radiation at z > 6.

Systematic variation of rare earths in monazite

USGS Publications Warehouse

Murata, K.J.; Rose, H.J.; Carron, M.K.

1953-01-01

Ten monazites from widely scattered localities have been analyzed for La, Ce, Pr, Nd, Sm, Gd, Y and Th by means of a combined chemical and emission spectrographic method. The analytical results, calculated to atomic percent of total rare earths (thorium excluded), show a considerable variation in the proportions of every element except praseodymium, which is relatively constant. The general variation trends of the elements may be calculated by assuming that the monazites represent different stages in a fractional precipitation process, and by assuming that there is a gradational increase in the precipitability of rare earth elements with decreasing ionic radius. Fractional precipitation brings about an increase in lanthanum and cerium, little change in praseodymium, and a decrease in neodymium, samarium, gadolinium, and yttrium. Deviations from the calculated lines of variation consist of a simultaneous, abnormal increase or decrease in the proportions of cerium, praseodymium, and neodymium with antipathetic decrease or increase in the proportions of the other elements. These deviations are ascribed to abnormally high or low temperatures that affect the precipitability of the central trio of elements (Ce, Pr, Nd) relatively more than that of the other elements. The following semiquantitative rules have been found useful in describing the composition of rare earths from monazite: 1. 1. The sum of lanthanum and neodymium is very nearly a constant at 42 ?? 2 atomic percent. 2. 2. Praseodymium is very nearly constant at 5 ?? 1 atomic percent. 3. 3. The sum of Ce, Sm, Gd, and Y is very nearly a constant at 53 ?? 3 atomic percent. No correlation could be established between the content of Th and that of any of the rare earth elements. ?? 1953.

Copper isotopic zonation in the Northparkes porphyry Cu-Au deposit, SE Australia

NASA Astrophysics Data System (ADS)

Li, Weiqiang; Jackson, Simon E.; Pearson, Norman J.; Graham, Stuart

2010-07-01

Significant, systematic Cu isotopic variations have been found in the Northparkes porphyry Cu-Au deposit, NSW, Australia, which is an orthomagmatic porphyry Cu deposit. Copper isotope ratios have been measured in sulfide minerals (chalcopyrite and bornite) by both solution and laser ablation multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS). The results from both methods show a variation in δ 65Cu of hypogene sulfide minerals of greater than 1‰ (relative to NIST976). Significantly, the results from four drill holes through two separate ore bodies show strikingly similar patterns of Cu isotope variation. The patterns are characterized by a sharp down-hole decrease from up to 0.8‰ (0.29 ± 0.56‰, 1 σ, n = 20) in the low-grade peripheral alteration zones (phyllic-propylitic alteration zone) to a low of ˜-0.4‰ (-0.25 ± 0.36‰, 1 σ, n = 30) at the margins of the most mineralized zones (Cu grade >1 wt%). In the high-grade cores of the systems, the compositions are more consistent at around 0.2‰ (0.19 ± 0.14‰, 1 σ, n = 40). The Cu isotopic zonation may be explained by isotope fractionation of Cu between vapor, solution and sulfides at high temperature, during boiling and sulfide precipitation processes. Sulfur isotopes also show an isotopically light shell at the margins of the high-grade ore zones, but these are displaced from the low δ 65Cu shells, such that there is no correlation between the Cu and S isotope signatures. Fe isotope data do not show any discernable variation along the drill core. This work demonstrates that Cu isotopes show a large response to high-temperature porphyry mineralizing processes, and that they may act as a vector to buried mineralization.

Impacts of environmental factors on the whole microbial communities in the rhizosphere of a metal-tolerant plant: Elsholtzia haichowensis Sun.

PubMed

Deng, Songqiang; Ke, Tan; Li, Longtai; Cai, Shenwen; Zhou, Yuyue; Liu, Yue; Guo, Limin; Chen, Lanzhou; Zhang, Dayi

2018-06-01

Rhizospheric microbes play important roles in plant growth and heavy metals (HMs) transformation, possessing great potential for the successful phytoremediation of environmental pollutants. In the present study, the rhizosphere of Elsholtzia haichowensis Sun was comprehensively studied to uncover the influence of environmental factors (EFs) on the whole microbial communities including bacteria, fungi and archaea, via quantitative polymerase chain reaction (qPCR) and high-throughput sequencing. By analyzing molecular ecological network and multivariate regression trees (MRT), we evaluated the distinct impacts of 37 EFs on soil microbial community. Of them, soil pH, HMs, soil texture and nitrogen were identified as the most influencing factors, and their roles varied across different domains. Soil pH was the main environmental variable on archaeal and bacterial community but not fungi, explaining 25.7%, 46.5% and 40.7% variation of bacterial taxonomic composition, archaeal taxonomic composition and a-diversity, respectively. HMs showed important roles in driving the whole microbial community and explained the major variation in different domains. Nitrogen (NH 4 -N, NO 3 -N, NO 2 -N and TN) explained 47.3% variation of microbial population composition and 15.9% of archaeal taxonomic composition, demonstrating its influence in structuring the rhizospheric microbiome, particularly archaeal and bacterial community. Soil texture accounted for 10.2% variation of population composition, 28.9% of fungal taxonomic composition, 19.2% of fungal a-diversity and 7.8% of archaeal a-diversity. Rhizosphere only showed strong impacts on fungi and bacteria, accounting for 14.7% and 4.9% variation of fungal taxonomic composition and bacterial a-diversity. Spatial distance had stronger influence on bacteria and archaea than fungi, but not as significant as other EFs. For the first time, our study provides a complete insight into key influential EFs on rhizospheric microbes and how their roles vary across microbial domains, giving a hand for understanding the construction of microbial communities in rhizosphere. Copyright © 2017 Elsevier Ltd. All rights reserved.

Relationship between climatic variables and the variation in bulk tank milk composition using canonical correlation analysis.

PubMed

Stürmer, Morgana; Busanello, Marcos; Velho, João Pedro; Heck, Vanessa Isabel; Haygert-Velho, Ione Maria Pereira

2018-06-04

A number of studies have addressed the relations between climatic variables and milk composition, but these works used univariate statistical approaches. In our study, we used a multivariate approach (canonical correlation) to study the impact of climatic variables on milk composition, price, and monthly milk production at a dairy farm using bulk tank milk data. Data on milk composition, price, and monthly milk production were obtained from a dairy company that purchased the milk from the farm, while climatic variable data were obtained from the National Institute of Meteorology (INMET). The data are from January 2014 to December 2016. Univariate correlation analysis and canonical correlation analysis were performed. Few correlations between the climatic variables and milk composition were found using a univariate approach. However, using canonical correlation analysis, we found a strong and significant correlation (r c  = 0.95, p value = 0.0029). Lactose, ambient temperature measures (mean, minimum, and maximum), and temperature-humidity index (THI) were found to be the most important variables for the canonical correlation. Our study indicated that 10.2% of the variation in milk composition, pricing, and monthly milk production can be explained by climatic variables. Ambient temperature variables, together with THI, seem to have the most influence on variation in milk composition.

Prokaryotic Nucleotide Composition Is Shaped by Both Phylogeny and the Environment

DOE PAGES

Reichenberger, Erin R.; Rosen, Gail; Hershberg, Uri; ...

2015-04-09

Here, the causes of the great variation in nucleotide composition of prokaryotic genomes have long been disputed. Here, we use extensive metagenomic and whole-genome data to demonstrate that both phylogeny and the environment shape prokaryotic nucleotide content. We show that across environments, various phyla are characterized by different mean guanine and cytosine (GC) values as well as by the extent of variation on that mean value. At the same time, we show that GC-content varies greatly as a function of environment, in a manner that cannot be entirely explained by disparities in phylogenetic composition. We find environmentally driven differences inmore » nucleotide content not only between highly diverged environments (e.g., soil, vs. aquatic vs. human gut) but also within a single type of environment. More specifically, we demonstrate that some human guts are associated with a microbiome that is consistently more GC-rich across phyla, whereas others are associated with a more AT-rich microbiome. These differences appear to be driven both by variations in phylogenetic composition and by environmental differences—which are independent of these phylogenetic composition differences. Combined, our results demonstrate that both phylogeny and the environment significantly affect nucleotide composition and that the environmental differences affecting nucleotide composition are far subtler than previously appreciated.« less

Relationship between climatic variables and the variation in bulk tank milk composition using canonical correlation analysis

NASA Astrophysics Data System (ADS)

Stürmer, Morgana; Busanello, Marcos; Velho, João Pedro; Heck, Vanessa Isabel; Haygert-Velho, Ione Maria Pereira

2018-06-01

A number of studies have addressed the relations between climatic variables and milk composition, but these works used univariate statistical approaches. In our study, we used a multivariate approach (canonical correlation) to study the impact of climatic variables on milk composition, price, and monthly milk production at a dairy farm using bulk tank milk data. Data on milk composition, price, and monthly milk production were obtained from a dairy company that purchased the milk from the farm, while climatic variable data were obtained from the National Institute of Meteorology (INMET). The data are from January 2014 to December 2016. Univariate correlation analysis and canonical correlation analysis were performed. Few correlations between the climatic variables and milk composition were found using a univariate approach. However, using canonical correlation analysis, we found a strong and significant correlation (r c = 0.95, p value = 0.0029). Lactose, ambient temperature measures (mean, minimum, and maximum), and temperature-humidity index (THI) were found to be the most important variables for the canonical correlation. Our study indicated that 10.2% of the variation in milk composition, pricing, and monthly milk production can be explained by climatic variables. Ambient temperature variables, together with THI, seem to have the most influence on variation in milk composition.

Arsenic distribution and valence state variation studied by fast hierarchical length-scale morphological, compositional, and speciation imaging at the Nanoscopium, Synchrotron Soleil

NASA Astrophysics Data System (ADS)

Somogyi, Andrea; Medjoubi, Kadda; Sancho-Tomas, Maria; Visscher, P. T.; Baranton, Gil; Philippot, Pascal

2017-09-01

The understanding of real complex geological, environmental and geo-biological processes depends increasingly on in-depth non-invasive study of chemical composition and morphology. In this paper we used scanning hard X-ray nanoprobe techniques in order to study the elemental composition, morphology and As speciation in complex highly heterogeneous geological samples. Multivariate statistical analytical techniques, such as principal component analysis and clustering were used for data interpretation. These measurements revealed the quantitative and valance state inhomogeneity of As and its relation to the total compositional and morphological variation of the sample at sub-μm scales.

Crystal nucleation in lithium borate glass

NASA Technical Reports Server (NTRS)

Smith, Gary L.; Neilson, George F.; Weinberg, Michael C.

1988-01-01

Crystal nucleation measurements were made on three lithium borate compositions in the vicinity of Li2O-2Br2O3. All nucleation measurements were performed at 500 C. Certain aspects of the nucleation behavior indicated (tentatively) that it proceeded by a homogeneous mechanism. The steady state nucleation rate was observed to have the largest value when the Li2O concentration was slightly in excess of the diborate composition. The change in nucleation rate with composition is controlled by the variation of viscosity as well as the change in free energy with composition. The variation of nucleation rate is explained qualitatively in these terms.

Seasonal variation in the Dutch bovine raw milk composition.

PubMed

Heck, J M L; van Valenberg, H J F; Dijkstra, J; van Hooijdonk, A C M

2009-10-01

In this study, we determined the detailed composition of and seasonal variation in Dutch dairy milk. Raw milk samples representative of the complete Dutch milk supply were collected weekly from February 2005 until February 2006. Large seasonal variation exists in the concentrations of the main components and milk fatty acid composition. Milk lactose concentration was rather constant throughout the season. Milk true protein content was somewhat more responsive to season, with the lowest content in June (3.21 g/100 g) and the highest content in December (3.38 g/100 g). Milk fat concentration increased from a minimum of 4.10 g/100 g in June to a maximum of 4.57 g/100 g in January. The largest (up to 2-fold) seasonal changes in the fatty acid composition were found for trans fatty acids, including conjugated linoleic acid. Milk protein composition was rather constant throughout the season. Milk unsaturation indices, which were used as an indication of desaturase activity, were lowest in spring and highest in autumn. Compared with a previous investigation of Dutch dairy milk in 1992, the fatty acid composition of Dutch raw milk has changed considerably, in particular with a higher content of saturated fatty acids in 2005 milk.

How gut transcriptional function of Drosophila melanogaster varies with the presence and composition of the gut microbiota.

PubMed

Bost, Alyssa; Franzenburg, Soeren; Adair, Karen L; Martinson, Vincent G; Loeb, Greg; Douglas, Angela E

2018-04-01

Despite evidence from laboratory experiments that perturbation of the gut microbiota affects many traits of the animal host, our understanding of the effect of variation in microbiota composition on animals in natural populations is very limited. The core purpose of this study on the fruit fly Drosophila melanogaster was to identify the impact of natural variation in the taxonomic composition of gut bacterial communities on host traits, with the gut transcriptome as a molecular index of microbiota-responsive host traits. Use of the gut transcriptome was validated by demonstrating significant transcriptional differences between the guts of laboratory flies colonized with bacteria and maintained under axenic conditions. Wild Drosophila from six field collections made over two years had gut bacterial communities of diverse composition, dominated to varying extents by Acetobacteraceae and Enterobacteriaceae. The gut transcriptomes also varied among collections and differed markedly from those of laboratory flies. However, no overall relationship between variation in the wild fly transcriptome and taxonomic composition of the gut microbiota was evident at all taxonomic scales of bacteria tested for both individual fly genes and functional categories in Gene Ontology. We conclude that the interaction between microbiota composition and host functional traits may be confounded by uncontrolled variation in both ecological circumstance and host traits (e.g., genotype, age physiological condition) under natural conditions, and that microbiota effects on host traits identified in the laboratory should, therefore, be extrapolated to field population with great caution. © 2017 John Wiley & Sons Ltd.

The Effect of Fiber Strength Stochastics and Local Fiber Volume Fraction on Multiscale Progressive Failure of Composites

NASA Technical Reports Server (NTRS)

Ricks, Trenton M.; Lacy, Jr., Thomas E.; Bednarcyk, Brett A.; Arnold, Steven M.

2013-01-01

Continuous fiber unidirectional polymer matrix composites (PMCs) can exhibit significant local variations in fiber volume fraction as a result of processing conditions that can lead to further local differences in material properties and failure behavior. In this work, the coupled effects of both local variations in fiber volume fraction and the empirically-based statistical distribution of fiber strengths on the predicted longitudinal modulus and local tensile strength of a unidirectional AS4 carbon fiber/ Hercules 3502 epoxy composite were investigated using the special purpose NASA Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC); local effective composite properties were obtained by homogenizing the material behavior over repeating units cells (RUCs). The predicted effective longitudinal modulus was relatively insensitive to small (8%) variations in local fiber volume fraction. The composite tensile strength, however, was highly dependent on the local distribution in fiber strengths. The RUC-averaged constitutive response can be used to characterize lower length scale material behavior within a multiscale analysis framework that couples the NASA code FEAMAC and the ABAQUS finite element solver. Such an approach can be effectively used to analyze the progressive failure of PMC structures whose failure initiates at the RUC level. Consideration of the effect of local variations in constituent properties and morphologies on progressive failure of PMCs is a central aspect of the application of Integrated Computational Materials Engineering (ICME) principles for composite materials.

A small variation in diet influences the Lactobacillus strain composition in the crop of broiler chickens.

PubMed

Hammons, Susan; Oh, Phaik Lyn; Martínez, Inés; Clark, Kenzi; Schlegel, Vicki L; Sitorius, Emily; Scheideler, Sheila E; Walter, Jens

2010-08-01

Feed composition has the potential to influence the activities of bacteria that colonize the digestive tract of broiler chickens with important consequences for animal health, well being, and food safety. In this study, the gut microbiota of two groups of broiler chickens raised in immediate vicinity but fed either a standard corn/soybean meal ration (corn-soy, CS) or a ration high in wheat middlings (high wheat, HW) was characterized. The findings revealed that this small variation in feed composition did not influence the distribution of microbial species present in the microbial community throughout the digestive tract. However, diet variation markedly influenced the Lactobacillus strain composition in the crop. Most striking, the dominant type in birds on the CS diet (Lactobacillus agilis type R5), which comprised 25% of the isolates, was not detected in birds fed the HW diet. The latter birds harbored a different strain of L. agilis (type R1) in a significantly higher ratio than birds on the CS diet. Several other strains were also specific to the particular diet. In conclusion, this study showed that a small variation in the composition of chicken feed that does not result in detectable differences in species composition can still have an impact on which microbial strains become dominant in the digestive tract. This finding has relevance in the application of probiotics and other direct-fed microbials in poultry husbandry. Copyright 2010 Elsevier GmbH. All rights reserved.

The systematics and population genetics of Opisthorchis viverrini sensu lato: implications in parasite epidemiology and bile duct cancer.

PubMed

Sithithaworn, Paiboon; Andrews, Ross H; Petney, Trevor N; Saijuntha, Weerachai; Laoprom, Nonglak

2012-03-01

Together with host and environmental factors, the systematics and population genetic variation of Opisthorchis viverrini may contribute to recorded local and regional differences in epidemiology and host morbidity in opisthorchiasis and cholangiocarcinoma (CCA). In this review, we address recent findings that O. viverrini comprises a species complex with varying degrees of population genetic variation which are associated with specific river wetland systems within Thailand as well as the Lao PDR. Having an accurate understanding of systematics is a prerequisite for a meaningful assessment of the population structure of each species within the O. viverrini complex in nature, as well as a better understanding of the magnitude of genetic variation that occurs within different species of hosts in its life cycle. Whether specific genotypes are related to habitat type(s) and/or specific intermediate host species are discussed based on current available data. Most importantly, we focus on whether there is a correlation between incidence of CCA and genotype(s) of O. viverrini. This will provide a solid basis for further comprehensive investigations of the role of genetic variation within each species of O. viverrini sensu lato in human epidemiology and genotype related morbidity as well as co-evolution of parasites with primary and secondary intermediate species of host. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Improved flaw detection and characterization with difference thermography

NASA Astrophysics Data System (ADS)

Winfree, William P.; Zalameda, Joseph N.; Howell, Patricia A.

2011-05-01

Flaw detection and characterization with thermographic techniques in graphite polymer composites is often limited by localized variations in the thermographic response. Variations in properties such as acceptable porosity, variations in fiber volume content and surface polymer thickness result in variations in the thermal response that in general cause significant variations in the initial thermal response. These variations result in a noise floor that increases the difficulty of detecting and characterizing deeper flaws. The paper investigates comparing thermographic responses taken before and after a change in state in a composite to improve the detection of subsurface flaws. A method is presented for registration of the responses before finding the difference. A significant improvement in the detectability is achieved by comparing the differences in response. Examples of changes in state due to application of a load and impact are presented.

Improved Flaw Detection and Characterization with Difference Thermography

NASA Technical Reports Server (NTRS)

Winfree, William P.; Zalameda, Joseph N.; Howell, Patricia A.

2011-01-01

Flaw detection and characterization with thermographic techniques in graphite polymer composites is often limited by localized variations in the thermographic response. Variations in properties such as acceptable porosity, variations in fiber volume content and surface polymer thickness result in variations in the thermal response that in general cause significant variations in the initial thermal response. These variations result in a noise floor that increases the difficulty of detecting and characterizing deeper flaws. The paper investigates comparing thermographic responses taken before and after a change in state in a composite to improve the detection of subsurface flaws. A method is presented for registration of the responses before finding the difference. A significant improvement in the detectability is achieved by comparing the differences in response. Examples of changes in state due to application of a load and impact are presented.

Tracking the evolution of a giant magmatic system from assembly to supereruption

NASA Astrophysics Data System (ADS)

Wotzlaw, J. F.; Schaltegger, U.; Frick, D. A.; Dungan, M. A.; Gerdes, A.; Günther, D.

2012-12-01

The chemical and physical characteristics of large magma bodies prior to eruption are closely related consequences of the balance between the rate of magma influx and the rate of cooling. The products of caldera-related silicic supereruptions, and less voluminous associated precursor and post-caldera activity preserve information about the thermal and chemical states of the system at the moment of evacuation of the magma chamber. Numerous studies of the Oligocene Fish Canyon Tuff (5000 km3; Colorado, USA) and related eruptive products of the La Garita caldera have addressed the origin and evolution of large-volume crystal-rich magmas. We use the presence of zircon in all eruptive products of the Fish Canyon magmatic system to gain a high-resolution geochronologic control on the thermal evolution of the magmatic system by using the trace element composition of U-Pb dated zircons as a proxy for magma crystallinity. New analytical protocols permit to obtain age, chemical and isotopic information from the exact same volume of single zircons (Schoene et al., 2010, GCA) allowing us to trace magma crystallinity as a function of time. Zircon U-Pb dates record ~400,000 years of crystallization. Variations in trace element composition in U-Pb dated zircons can be attributed to trace element fractionation imposed by co-crystallization of titanite. Due to the relatively high modal abundance of titanite in Fish Canyon magma and the extreme compatibility of the rare earth elements (REE) in this phase, titanite is the major control on many trace element concentrations and ratios (e.g. Yb/Dy) in coexisting zircons via varying degrees of depletion of these elements in the host melt. Modeling of compositional variations as a result of fractional crystallization suggests that the range of zircon compositions can be explained by 50-70% crystallization of a fractionating assemblage containing 0.4-0.8 vol.% titanite. The period of cooling centered around 28.4 Ma and is marked by an apparent crystallinity that is ~30% higher than at the time of eruption, implying that the Fish Canyon magma was perilously close to complete solidification, hence 'plutonic death', prior to late reheating. We estimate the duration of the reheating event from the age difference of the chemically most evolved (highest Yb/Dy) and the youngest dated zircon to be ~170 ka. This duration for reactivation of the near solidus crystal mush is in excellent agreement with estimates derived from numerical modeling of remelting by upward percolation of a hot gas-phase derived from underplated mafic magma ('gas sparging'; Bachmann and Bergantz, 2003, Geology). This investigation, which is the first in which high resolution U-Pb zircon geochronology has been coupled with geochemical modeling of systematic compositional variations in an accessory mineral, ties together many of the threads which have been developed independently during previous studies of the Fish Canyon magmatic system and places related petrogenetic processes into an absolute time frame.

Low flower-size variation in bilaterally symmetrical flowers: Support for the pollination precision hypothesis.

PubMed

Nikkeshi, Aoi; Kurimoto, Daiki; Ushimaru, Atushi

2015-12-01

The evolutionary shift from radial to bilateral symmetry in flowers is generally associated with the evolution of low flower-size variation. This phenomenon supports the hypothesis that the lower size variation in bilateral flowers can be attributed to low pollinator diversity. In this study, we propose two other hypotheses to explain low flower-size variation in bilateral symmetrical flowers. To test the three hypotheses, we examined the relative importance of pollinator diversity, composition, and bilateral symmetry itself as selective forces on low flower-size variation. We examined pollinator diversity and composition and flower-size variation for 36 species in a seminatural ecosystem with high bee richness and frequent lepidopteran visitation. Bilateral flowers were more frequently visited than radial flowers by larger bees, but functional-group diversity of the pollinators did not differ between symmetry types. Although bilateral flowers had significantly lower flower-size variation than radial flowers, flower-size variation did not vary with pollinator diversity and composition but was instead related to bilateral symmetry. Our results suggest that the lower size variation in bilateral flowers might have evolved under selection favoring the control of pollinator behavior on flowers to enhance the accurate placement of pollen on the body of the pollinator, independent of pollinator type. Because of the limited research on this issue, future work should be conducted in various types of plant-pollinator communities worldwide to further clarify the issue. © 2015 Botanical Society of America.

Influence of structural variation on nuclear localization of DNA-binding polyamide-fluorophore conjugates.

PubMed

Edelson, Benjamin S; Best, Timothy P; Olenyuk, Bogdan; Nickols, Nicholas G; Doss, Raymond M; Foister, Shane; Heckel, Alexander; Dervan, Peter B

2004-01-01

A pivotal step forward in chemical approaches to controlling gene expression is the development of sequence-specific DNA-binding molecules that can enter live cells and traffic to nuclei unaided. DNA-binding polyamides are a class of programmable, sequence-specific small molecules that have been shown to influence a wide variety of protein-DNA interactions. We have synthesized over 100 polyamide-fluorophore conjugates and assayed their nuclear uptake profiles in 13 mammalian cell lines. The compiled dataset, comprising 1300 entries, establishes a benchmark for the nuclear localization of polyamide-dye conjugates. Compounds in this series were chosen to provide systematic variation in several structural variables, including dye composition and placement, molecular weight, charge, ordering of the aromatic and aliphatic amino-acid building blocks and overall shape. Nuclear uptake does not appear to be correlated with polyamide molecular weight or with the number of imidazole residues, although the positions of imidazole residues affect nuclear access properties significantly. Generally negative determinants for nuclear access include the presence of a beta-Ala-tail residue and the lack of a cationic alkyl amine moiety, whereas the presence of an acetylated 2,4-diaminobutyric acid-turn is a positive factor for nuclear localization. We discuss implications of these data on the design of polyamide-dye conjugates for use in biological systems.

A review of isotopic composition as an indicator of the natural and anthropogenic behavior of mercury

USGS Publications Warehouse

Ridley, W.I.; Stetson, S.J.

2006-01-01

There are seven stable isotopes of Hg that can be fractionated as a result of inorganic and organic interactions. Important inorganic reactions involve speciation changes resulting from variations in environmental redox conditions, and phase changes resulting from variations in temperature and/or atmospheric pressure. Important organic reactions include methylation and demethylation, reactions that are bacterially mediated, and complexing with organic anions in soils. The measurement of Hg isotopes by multi-collector-inductively coupled plasma-mass spectrometry (MC-ICP-MS) is now sufficiently precise and sensitive that it is potentially possible to develop the systematics of Hg isotopic fractionation. This provides an opportunity to evaluate the utility of Hg isotopes in identifying source processes, transport mechanisms, and sinks. New values are provided for, 201Hg/198Hg, 200Hg/198Hg, 199Hg/198Hg for three standard materials (IRMM-AE639, SRM 1641c, SRM 3133) that can be used to make inter-laboratory data comparisons, and these values are tabulated with published isotopic information. Overall, the isotopic data for these standards agree to approximately 0.2???. The paper reviews Hg isotope studies that deal with hydrothermal ore deposits, sediments, coal and organic complexing. ?? 2006 Elsevier Ltd. All rights reserved.

Interaction networks and the use of floral resources by male orchid bees (Hymenoptera: Apidae: Euglossini) in a primary rain forests of the Chocó Region (Colombia).

PubMed

Ospina-Torres, Rodulfo; Montoya-Pfeiffer, Paula María; Parra-H, Alejandro; Solarte, Victor; Tupac Otero, Joel

2015-09-01

Orchid bees are important keystone pollinators from the Neotropics. With the aim to study the relationships between orchid bees and their nectar and aromatic host species, we made systematic samplings of males across two conservation areas in the biogeographic Choc6 Region of Colombia. We used chemical baits to collect 352 male bees during five months. The pollen attached to their bodies was extracted for palynological identification and to estimate interaction networks. The euglossine community consisted of at least 22 species including Eg. maculilabris, Eg. orellana, Eg. championi and Eg. ignita. The male bees were associated with 84 plants but depended on a small group of them (Peperomia spp. and Anthurium spp, as well as species of Solanaceae, Ericaceae and Malpighiaceae) which were widely distributed across the altitudinal gradient, and were available through the year. The resulting interaction networks revealed a typical nested pattern usually found in plant-pollinator interactions, with several rare bee and plant species interaction with a small group of generalist bees and plant species. Albeit, we found variation within networks related to species composition. Such variation may be a consequence of specific differences in plant flowering phenology.

Motion planning for an adaptive wing structure with macro-fiber composite actuators

NASA Astrophysics Data System (ADS)

Schröck, J.; Meurer, T.; Kugi, A.

2009-05-01

A systematic approach for flatness-based motion planning and feedforward control is presented for the transient shaping of a piezo-actuated rectangular cantilevered plate modeling an adaptive wing. In the first step the consideration of an idealized infinite-dimensional input allows to determine the state and input parametrization in terms of a flat or basic output, which is used for a systematic motion planning approach. Subsequently, the obtained idealized input function is projected onto a finite number of suitably placed Macro-fiber Composite (MFC) patch actuators. The tracking performance of the proposed approach is evaluated in a simulation scenario.

Compositional structure of the asteroid belt.

PubMed

Gradie, J; Tedesco, E

1982-06-25

The distribution of compositional types among the asteroids is found to vary systematically with heliocentric distance. Seven distinct peaks in the relative proportion of the compositional types E, R, S, M, F, C, P, and D are found from 1.8 to 5.2 astronomical units. The inferred composition of the asteroids in each semimajor axis region is consistent with the theory that the asteroids accreted from the solar nebula at or near their present locations.

Environmental and spatial drivers of taxonomic, functional, and phylogenetic characteristics of bat communities in human-modified landscapes.

PubMed

Cisneros, Laura M; Fagan, Matthew E; Willig, Michael R

2016-01-01

Assembly of species into communities following human disturbance (e.g., deforestation, fragmentation) may be governed by spatial (e.g., dispersal) or environmental (e.g., niche partitioning) mechanisms. Variation partitioning has been used to broadly disentangle spatial and environmental mechanisms, and approaches utilizing functional and phylogenetic characteristics of communities have been implemented to determine the relative importance of particular environmental (or niche-based) mechanisms. Nonetheless, few studies have integrated these quantitative approaches to comprehensively assess the relative importance of particular structuring processes. We employed a novel variation partitioning approach to evaluate the relative importance of particular spatial and environmental drivers of taxonomic, functional, and phylogenetic aspects of bat communities in a human-modified landscape in Costa Rica. Specifically, we estimated the amount of variation in species composition (taxonomic structure) and in two aspects of functional and phylogenetic structure (i.e., composition and dispersion) along a forest loss and fragmentation gradient that are uniquely explained by landscape characteristics (i.e., environment) or space to assess the importance of competing mechanisms. The unique effects of space on taxonomic, functional and phylogenetic structure were consistently small. In contrast, landscape characteristics (i.e., environment) played an appreciable role in structuring bat communities. Spatially-structured landscape characteristics explained 84% of the variation in functional or phylogenetic dispersion, and the unique effects of landscape characteristics significantly explained 14% of the variation in species composition. Furthermore, variation in bat community structure was primarily due to differences in dispersion of species within functional or phylogenetic space along the gradient, rather than due to differences in functional or phylogenetic composition. Variation among bat communities was related to environmental mechanisms, especially niche-based (i.e., environmental) processes, rather than spatial mechanisms. High variation in functional or phylogenetic dispersion, as opposed to functional or phylogenetic composition, suggests that loss or gain of niche space is driving the progressive loss or gain of species with particular traits from communities along the human-modified gradient. Thus, environmental characteristics associated with landscape structure influence functional or phylogenetic aspects of bat communities by effectively altering the ways in which species partition niche space.

Environmental and spatial drivers of taxonomic, functional, and phylogenetic characteristics of bat communities in human-modified landscapes

PubMed Central

Fagan, Matthew E.; Willig, Michael R.

2016-01-01

Background Assembly of species into communities following human disturbance (e.g., deforestation, fragmentation) may be governed by spatial (e.g., dispersal) or environmental (e.g., niche partitioning) mechanisms. Variation partitioning has been used to broadly disentangle spatial and environmental mechanisms, and approaches utilizing functional and phylogenetic characteristics of communities have been implemented to determine the relative importance of particular environmental (or niche-based) mechanisms. Nonetheless, few studies have integrated these quantitative approaches to comprehensively assess the relative importance of particular structuring processes. Methods We employed a novel variation partitioning approach to evaluate the relative importance of particular spatial and environmental drivers of taxonomic, functional, and phylogenetic aspects of bat communities in a human-modified landscape in Costa Rica. Specifically, we estimated the amount of variation in species composition (taxonomic structure) and in two aspects of functional and phylogenetic structure (i.e., composition and dispersion) along a forest loss and fragmentation gradient that are uniquely explained by landscape characteristics (i.e., environment) or space to assess the importance of competing mechanisms. Results The unique effects of space on taxonomic, functional and phylogenetic structure were consistently small. In contrast, landscape characteristics (i.e., environment) played an appreciable role in structuring bat communities. Spatially-structured landscape characteristics explained 84% of the variation in functional or phylogenetic dispersion, and the unique effects of landscape characteristics significantly explained 14% of the variation in species composition. Furthermore, variation in bat community structure was primarily due to differences in dispersion of species within functional or phylogenetic space along the gradient, rather than due to differences in functional or phylogenetic composition. Discussion Variation among bat communities was related to environmental mechanisms, especially niche-based (i.e., environmental) processes, rather than spatial mechanisms. High variation in functional or phylogenetic dispersion, as opposed to functional or phylogenetic composition, suggests that loss or gain of niche space is driving the progressive loss or gain of species with particular traits from communities along the human-modified gradient. Thus, environmental characteristics associated with landscape structure influence functional or phylogenetic aspects of bat communities by effectively altering the ways in which species partition niche space. PMID:27761338

Genomic and evolutionary characteristics of cattle copy number variations

USDA-ARS?s Scientific Manuscript database

We performed a systematic analysis of cattle copy number variations (CNVs) using the Bovine HapMap SNP genotyping data, including 539 animals of 21 modern cattle breeds and 6 outgroups. After correcting genomic waves and considering the trio information, we identified 682 candidate CNV regions (CNVR...

The Apollo 17 'melt sheet' - Chemistry, age and Rb/Sr systematics

NASA Technical Reports Server (NTRS)

Winzer, S. R.; Nava, D. F.; Schuhmann, S.; Philpotts, J. A.; Schuhmann, P. J.; Lum, R. K. L.; Lindstrom, M. M.; Lindstrom, D. J.

1977-01-01

Major, minor, and trace-element compositions, age data, and Rb/Sr systematics of Apollo 17 boulders have been compiled, and additional analyses performed on a norite breccia clast (77215) included in the Apollo 17, Station 7 boulder. The Apollo 17 boulders are found to be identical or nearly so in major, minor, and trace-element composition, suggesting that they all originated as an impact melt analogous to melt sheets found in larger terrestrial craters. The matrix dates (Ar-40/Ar-39) and Rb/Sr systematics available suggest that this impact melt formed by a single impact about 4 billion years ago. This impact excavated, shocked, brecciated, and melted norites, norite cumulates, and possibly anorthositic gabbros and dunites about 4.4 billion years old. The impact was likely a major one, possibly the Serenitatis basin-forming event.

Age variations in anthropometric and body composition characteristics and undernutrition among female Bathudis: a tribal population of Keonjhar District, Orissa, India.

PubMed

Bose, Kaushik; Chakraborty, Falguni; Bisai, Samiran

2007-09-01

A cross-sectional study of 183 female Bathudis, a tribal population of the Keonjhar District, Orissa, India, was undertaken to investigate age variations in anthropometric and body composition characteristics and nutritional status. The subjects were categorized into three age groups: < or =30 years, 31-50 years, >50 years. Height, weight, circumferences and skinfolds data were collected. Body mass index (BMI) and several body composition variables and indices were derived using standard equations. The results revealed that there existed significant negative age variations for most of the anthropometric and body composition variables and indices. Correlation studies of age with these variables and indices revealed significant negative correlations. Linear regression analyses revealed that for all variables, age had a significant negative impact. Studies on the nutritional status of these women revealed that with increasing age, there was an increase in the frequency of undernutrition. In conclusion, this study demonstrated that among Bathudi women, age was significantly negatively related with anthropometric and body composition variables and indices. Moreover, with increasing age, the level of undernutrition increased.

High-precision isotopic characterization of USGS reference materials by TIMS and MC-ICP-MS

NASA Astrophysics Data System (ADS)

Weis, Dominique; Kieffer, Bruno; Maerschalk, Claude; Barling, Jane; de Jong, Jeroen; Williams, Gwen A.; Hanano, Diane; Pretorius, Wilma; Mattielli, Nadine; Scoates, James S.; Goolaerts, Arnaud; Friedman, Richard M.; Mahoney, J. Brian

2006-08-01

The Pacific Centre for Isotopic and Geochemical Research (PCIGR) at the University of British Columbia has undertaken a systematic analysis of the isotopic (Sr, Nd, and Pb) compositions and concentrations of a broad compositional range of U.S. Geological Survey (USGS) reference materials, including basalt (BCR-1, 2; BHVO-1, 2), andesite (AGV-1, 2), rhyolite (RGM-1, 2), syenite (STM-1, 2), granodiorite (GSP-2), and granite (G-2, 3). USGS rock reference materials are geochemically well characterized, but there is neither a systematic methodology nor a database for radiogenic isotopic compositions, even for the widely used BCR-1. This investigation represents the first comprehensive, systematic analysis of the isotopic composition and concentration of USGS reference materials and provides an important database for the isotopic community. In addition, the range of equipment at the PCIGR, including a Nu Instruments Plasma MC-ICP-MS, a Thermo Finnigan Triton TIMS, and a Thermo Finnigan Element2 HR-ICP-MS, permits an assessment and comparison of the precision and accuracy of isotopic analyses determined by both the TIMS and MC-ICP-MS methods (e.g., Nd isotopic compositions). For each of the reference materials, 5 to 10 complete replicate analyses provide coherent isotopic results, all with external precision below 30 ppm (2 SD) for Sr and Nd isotopic compositions (27 and 24 ppm for TIMS and MC-ICP-MS, respectively). Our results also show that the first- and second-generation USGS reference materials have homogeneous Sr and Nd isotopic compositions. Nd isotopic compositions by MC-ICP-MS and TIMS agree to within 15 ppm for all reference materials. Interlaboratory MC-ICP-MS comparisons show excellent agreement for Pb isotopic compositions; however, the reproducibility is not as good as for Sr and Nd. A careful, sequential leaching experiment of three first- and second-generation reference materials (BCR, BHVO, AGV) indicates that the heterogeneity in Pb isotopic compositions, and concentrations, could be directly related to contamination by the steel (mortar/pestle) used to process the materials. Contamination also accounts for the high concentrations of certain other trace elements (e.g., Li, Mo, Cd, Sn, Sb, W) in various USGS reference materials.

A 120 ka record of reconstructed paleoprecipitation signals at Lake El'gygytgyn, NE Russia derived from compound-specific δD analysis of terrestrial biomarkers

NASA Astrophysics Data System (ADS)

Wilkie, K. M.; Chapligin, B.; Burns, S. J.; Petsch, S.; Meyer, H.; Brigham-Grette, J.

2011-12-01

Sediment cores recovered from Lake El'gygytgyn, NE Russia extend back to 3.6Ma, representing the longest time-continuous sediment record of past climate change in the terrestrial Arctic. Comparison of the stable isotope composition of modern precipitation and compound-specific isotopic analyses of modern vegetation and sedimentary lipids from the last 120ka allows reconstruction of past hydrological conditions, thereby providing a powerful tool for reconstructing past Arctic climate changes. The stable isotopic composition of modern precipitation, streams, and lake water are presented and used to constrain isotope systematics of the Lake El'gygytgyn Basin hydrology. The hydrogen isotopic compositions (δD) of alkanoic acids from modern vegetation are compared with modern precipitation and lake core top sediments. Multi-species net fractionation values between source water and leaf wax lipid δD values (-113 ± 13%) agree with previous results in arid environments and provide a basis for applying this proxy further downcore. δD measurements of sedimentary alkanoic acids representing terrestrial sources (e.g. δDTER: nC30) show significant variation (up to 70%) over the past 120 ka. Interglacial periods are characterized by isotopic enrichment while the most negative δDTER values occur during glacial conditions (i.e. the Last Glacial Maximum and MIS 4). Preliminary reconstruction of the isotopic composition of past precipitation from the δDTER record correlates strongly with the δ18Ocalcite record from Sanbao and Hulu caves1 (China) and the δDvostok record2 (Antarctica) suggesting global teleconnections and 'circum-Pacific' coherence to paleo-precipitation archives. 1 Wang et al. (2005), Science 308, 854-857. 2 Petit et al. (1999), Nature 399, 429-436.

Reaction microtextures in entrapped xenoliths in alkali basalts from the Deccan large igneous province, India: Implications to the origin and evolution

NASA Astrophysics Data System (ADS)

Chattopadhaya, Soumi; Ghosh, Biswajit; Morishita, Tomoaki; Nandy, Sandip; Tamura, Akihiro; Bandyopadhyay, Debaditya

2017-05-01

The onset of the end-Mesozoic continental rift magmatism in the Deccan volcanic province (DVP), India is marked by alkali magmatism. Lithospheric fragments occurring as xenoliths/xenocrysts entrapped in alkaline basalts from the Kutch area of the DVP preserve reaction microtextures giving an insight into the processes linked to their origin. We interpret the flower texture, an aggregate of systematically arranged tiny diopside crystals, as a product of interactions between ghost quartz xenocrysts with alkaline silica-undersaturated melt. The mantle xenoliths, mostly represented by spinel lherzolites and wehrlites have been infiltrated by melt. The orthopyroxenes present at the margin of the xenoliths or in contact with infiltrated melt exhibit a coronal texture composed of olivine, clinopyroxene and glass around them. The compositions of cores of primary olivines at places retain mantle signatures, whereas, the margins are reequilibrated. Secondary olivines and clinopyroxenes at reaction coronas have a wide range of compositions. Primary clinopyroxenes and spinels in close vicinity to the orthopyroxene corona display a sieve texture defined by clear inclusion-free cores and a compositionally different spongy altered rim with worm-shaped or bubbly inclusions dominantly filled with glass. The rims are marked with higher Ca, Mg-lower Na, Al for clinopyroxenes and higher Ti, Cr-lower Mg, Al for spinels in comparison to their cores. The coronal texture around orthopyroxenes and spongy texture in clinopyroxenes and spinels in these xenoliths are interpreted to be genetically linked. The silicate glasses in the xenoliths show large compositional variations and they are much more siliceous and alkali-rich in comparison to the host basalts. The petrography and mineral chemistry suggest host magma-peridotite interaction during or after the entrainment of the xenoliths, corroborating well with the experimental findings.

Methane concentration and isotopic composition (δ13C-CH4) in the Nerja Cave system (South Spain)

NASA Astrophysics Data System (ADS)

Vadillo, Iñaki; Etiope, Giuseppe; Benavente, José; Ojeda, Lucia; Liñán, Cristina; Carrasco, Francisco

2016-04-01

Air in underground caves often has methane (CH4) concentrations below the atmospheric level, due to methanotrophic or other unkown CH4 consuming processes. Caves are thus considered a potential sink for atmospheric methane. If globally important, this underground CH4 oxidation should be taken into account in the atmospheric methane budget, in addition to the known soil methanotrophy and tropospheric/stratospheric sinks. A large set of data is however necessary to understand how and how much methane from external atmospheric air is consumed in the caves. While methane concentration data are available for several caves worldwide, its isotopic composition and variations in space and time are poorly documented. We measured methane concentration and stable C isotope composition (δ13C) in the Nerja cave (Southern Spain) air during two surveys in March and April 2015. CH4 concentration decreases progressively from the more external cave rooms, with atmospheric levels of 1.9 ppmv, to the more internal and isolated rooms down to 0.5 ppmv. δ13C increases correspondingly from -47 ‰ to -41 ‰ (VPDB). CH4 is systematically 13C-enriched (δ13C > -45) in areas of the cave where the concentration is below 1.4 ppmv. This combination of concentration decrease and 13C-enrichment towards the more internal and isolated zones of the cave confirms the importance of CH4 oxidation, likely driven by methanotrophic bacteria. Further data, including stable H isotope composition of sub-atmospheric CH4 concentrations, CO2 and microbial analyses, shall be acquired over time to assess the actual role of methanotrophic bacteria and seasonal controls in the CH4 consumption process.

Effect of a surface sealant on the color stability of composite resins after immersion in staining solution.

PubMed

Pedroso, Lauana Borges; Barreto, Luma Franciélle Cabreira; Miotti, Leonardo Lamberti; Nicoloso, Gabriel Ferreira; Durand, Leticia Brandão

2016-01-01

This study evaluated the influence of surface sealants on the color stability of 2 different composite resins after immersion in coffee. Four groups were created (n = 10): microhybrid composite, microhybrid with surface sealant, nanofilled composite, and nanofilled composite with surface sealant. Half of the specimens of each group were immersed in distilled water and half were immersed in coffee for 48 hours. Color was measured before and after immersion. Groups with surface sealants presented less color variation when compared with the groups without surface sealants. The nanofilled resin specimens presented the greatest color variation within the groups without sealant. The surface sealant positively influenced the color stability of composite resin specimens immersed in coffee. When surface sealant was not applied, the microhybrid specimens had better color stability than the nanofilled.

Study of structural, electronic and magneto transport properties of La0.7Ca0.2-xSrxAg0.1MnO3

NASA Astrophysics Data System (ADS)

Subhashini, P.; Munirathinum, B.; Krishnaiah, M.; Venkatesh, R.; Venkateswarlu, D.; Ganesan, V.

2016-10-01

Structural, electrical and magneto transport properties of Lanthanum based manganites La0.7Ca0.2-xSrxAg0.1MnO3 (x=0 & 0.1) synthesized by low temperature nitrate route is studied systematically. The X-ray Diffraction patterns confirm the presence of orthorhombic structure with Pnma space group. The temperature dependence of MR (-35%) from 233-272K for x=0 and an MR (-26%) from 281-309K for x=0.1composition with an overall variation of 1% is very much advantageous for device application. Interestingly, in low temperature regime, the MR value of -47% obtained in x=0.1 composition at 10T around 5K is 20% higher than the MR obtained at 10T around the metal insulator transition. Significant changes happening in the low temperature MR measurements is discussed in the light of electron-electron interactions and weak localization mechanisms while the additional broad hump responsible for flat MR is attributed to the intrinsic electronic in homogeneity driven phase competition created due to the presence of mono valent Ag ions. The complex localization mechanism associated with insulating regime is in accordance with Variable range hopping of small polarons.

Determination of the second virial coefficient of bovine serum albumin under varying pH and ionic strength by composition-gradient multi-angle static light scattering.

PubMed

Ma, Yingfang; Acosta, Diana M; Whitney, Jon R; Podgornik, Rudolf; Steinmetz, Nicole F; French, Roger H; Parsegian, V Adrian

2015-01-01

Composition-gradient multi-angle static light scattering (CG-MALS) is an emerging technique for the determination of intermolecular interactions via the second virial coefficient B22. With CG-MALS, detailed studies of the second virial coefficient can be carried out more accurately and effectively than with traditional methods. In addition, automated mixing, delivery and measurement enable high speed, continuous, fluctuation-free sample delivery and accurate results. Using CG-MALS we measure the second virial coefficient of bovine serum albumin (BSA) in aqueous solutions at various values of pH and ionic strength of a univalent salt (NaCl). The systematic variation of the second virial coefficient as a function of pH and NaCl strength reveals the net charge change and the isoelectric point of BSA under different solution conditions. The magnitude of the second virial coefficient decreases to 1.13 x 10(-5) ml*mol/g(2) near the isoelectric point of pH 4.6 and 25 mM NaCl. These results illuminate the role of fundamental long-range electrostatic and van der Waals forces in protein-protein interactions, specifically their dependence on pH and ionic strength.

Direct synthesis of hydrogen peroxide and benzyl alcohol oxidation using Au-Pd catalysts prepared by sol immobilization.

PubMed

Pritchard, James; Kesavan, Lokesh; Piccinini, Marco; He, Qian; Tiruvalam, Ramchandra; Dimitratos, Nikolaos; Lopez-Sanchez, Jose A; Carley, Albert F; Edwards, Jennifer K; Kiely, Christopher J; Hutchings, Graham J

2010-11-02

We report the preparation of Au-Pd nanocrystalline catalysts supported on activated carbon prepared via a sol-immobilization technique and explore their use for the direct synthesis of hydrogen peroxide and the oxidation of benzyl alcohol. In particular, we examine the synthesis of a systematic set of Au-Pd colloidal nanoparticles having a range of Au/Pd ratios. The catalysts have been structurally characterized using a combination of UV-visible spectroscopy, transmission electron microscopy, STEM HAADF/XEDS, and X-ray photoelectron spectroscopy. The Au-Pd nanoparticles are found in the majority of cases to be homogeneous alloys, although some variation is observed in the AuPd composition at high Pd/Au ratios. The optimum performance for the synthesis of hydrogen peroxide is observed for a catalyst having a Au/Pd 1:2 molar ratio. However, the competing hydrogenation reaction of hydrogen peroxide increases with increasing Pd content, although Pd alone is less effective than when Au is also present. Investigation of the oxidation of benzyl alcohol using these materials also shows that the optimum selective oxidation to the aldehyde occurs for the Au/Pd 1:2 molar ratio catalyst. These measured activity trends are discussed in terms of the structure and composition of the supported Au-Pd nanoparticles.

Occurrence and source apportionment of Per- and poly-fluorinated compounds (PFCs) in North Canal Basin, Beijing

PubMed Central

Zhang, Yi-Zhe; Wang, Bin; Wang, Wei; Li, Wen-Chao; Huang, Jun; Deng, Shu-Bo; Wang, Yu-Jue; Yu, Gang

2016-01-01

Various per- and poly-fluorinated compounds (PFCs) were first systematically investigated in North Canal Basin, Beijing, China. A total of 68 surface water samples were collected from North Canal Basin, Beijing, at high spatial resolution. The seasonal disparity was compared and associated with source variation. PFCs concentrations in low-water period ranged from 26 to 207 ng/L, and significantly declined levels were found in high-water period. The individual component proportions among different sites varied less in high-water period, when runoff played a role in mixing and diluting PFCs. A methodology combined with principal component analysis (PCA), heat map-hierarchical cluster analysis (HM-HCA), and correlation analysis were introduced to discriminate sources of PFCs in surface water. The statistical results agreed with each other, and daily domestic consumption, fire-fighting products and related industries were identified as sources of PFCs in this region. In addition, two composition ratios were proposed through the methodology to distinguish the impact of nonpoint source, and the outcome demonstrates that great disparities exist in compositional profiles between nonpoint source and others. Overall, the results showed that this comprehensive analysis method has great potential for source apportionment in surface water and other environmental compartments. PMID:27845351

Structure Study on Microemulsion System with an Ionic Liquid (IL) by Small-Angle Neutron Scattering

NASA Astrophysics Data System (ADS)

Kang, Tae Hui; Qian, Shuo; Smith, Gregory S.; Do, Changwoo; Heller, William T.

The self-assembly of IL with a long alkyl chains provides molecular level control on the structure enabling applications, including, creating microemulsion with dual functions of extractant and surfactant. The IL, C14MIMCl is not soluble in alkane solvents, even with the addition of octanol. However, with a small amount of water, a water-in-oil micromemulsion forms, that obeys the swelling law with water content. The mixed surfactant system, C14MIMCl/octanol, has different chemistry and molecular geometries depending on its composition. Through the use of SANS, it is possible to determine the impact of the surfactant system on the structure of the microemulsion, as well as to learn the composition of various regions in the structure. The microemulsion system was studied by dilution with octane from 10 to 70 wt%. A strong intensity peak was observed near 0.1 Å-1, and the stable phase shows a structural transition at 30 wt% octane. Contrast variation experiments were done with d-octane and h-octane to understand the structure of the microemulsion, as well as the structural transition. Further, systematic concentration studies of surfactant at constant water-to-oil molar ratio and of water at constant 30 wt% surfactant were performed.

Microstructure and mechanical properties of horns derived from three domestic bovines.

PubMed

Zhang, Quan-bin; Li, Chun; Pan, Yan-ting; Shan, Guang-hua; Cao, Ping; He, Jia; Lin, Zhong-shi; Ao, Ning-jian; Huang, Yao-xiong

2013-12-01

The microstructure and mechanical properties of horns derived from three domestic bovines (buffalo, cattle and sheep) were examined. The effects of water content, sampling position and orientation of three bovid horns on mechanical properties were systematically investigated by uniaxial tension and micron indentation tests. Meanwhile, the material composition and metal element contents were determined by Raman spectroscopy and elemental analysis respectively, and the microstructures of the horns were measured by scanning electron microscopy (SEM). Results show that the mechanical properties of horns have negative correlation with water contents and depend on sampling position and orientation. The spatial variations of the mechanical properties in horns are attributed to the different keratinization degrees in the proximal, middle and distal parts. And the mechanical properties of horns in the longitudinal direction are better than those in transverse. Among the three kinds of horns, the mechanical properties of buffalo horn are the best, followed by cattle horn, and those in sheep horn are the worst. This is due to the differences in material composition, metal element, and the microstructures of the horns. But the mechanical properties of buffalo horns are not dependent on the source of the buffalo. Therefore, regular engineered buffalo keratinous materials with standard mechanical properties can be obtained from different buffalo horns by using proper preparation methods. © 2013.

Carbon Nanofibers and Their Composites: A Review of Synthesizing, Properties and Applications

PubMed Central

Feng, Lichao; Xie, Ning; Zhong, Jing

2014-01-01

Carbon nanofiber (CNF), as one of the most important members of carbon fibers, has been investigated in both fundamental scientific research and practical applications. CNF composites are able to be applied as promising materials in many fields, such as electrical devices, electrode materials for batteries and supercapacitors and as sensors. In these applications, the electrical conductivity is always the first priority need to be considered. In fact, the electrical property of CNF composites largely counts on the dispersion and percolation status of CNFs in matrix materials. In this review, the electrical transport phenomenon of CNF composites is systematically summarized based on percolation theory. The effects of the aspect ratio, percolation backbone structure and fractal characteristics of CNFs and the non-universality of the percolation critical exponents on the electrical properties are systematically reviewed. Apart from the electrical property, the thermal conductivity and mechanical properties of CNF composites are briefly reviewed, as well. In addition, the preparation methods of CNFs, including catalytic chemical vapor deposition growth and electrospinning, and the preparation methods of CNF composites, including the melt mixing and solution process, are briefly introduced. Finally, their applications as sensors and electrode materials are described in this review article. PMID:28788657

A general method for the layout of ailerons and elevators of gliders and motorplanes

NASA Technical Reports Server (NTRS)

Hiller, M. H.

1979-01-01

A method is described which allows the layout of the spatial driving mechanism of the aileron for a glider or a motorplane to be performed in a systematic manner. In particular, a prescribed input-output behavior of the mechanism can be realized by variation of individual parameters of the spatial four-bar mechanisms which constitute the entire driving mechanism. By means of a sensitivity analysis, a systematic choice of parameters is possible. At the same time the forces acting in the mechanism can be limited by imposing maximum values of the forces as secondary conditions during the variation process.

Variation in Content Coverage by Classroom Composition: An Analysis of Advanced Math Course Content

ERIC Educational Resources Information Center

Covay, Elizabeth

2011-01-01

Everyone knows that there is racial inequality in achievement returns from advanced math; however, they do not know why black students and white students taking the same level of math courses are not leaving with the same or comparable skill levels. To find out, the author examines variation in course coverage by the racial composition of the…

Comparison of TIMS and MC-ICP-MS Analyses of Pb Isotopic Compositions on Prehistoric Mauna Loa Basalts: Implications for Plume Source Components

NASA Astrophysics Data System (ADS)

De Jong, J.; Weis, D.; Maerschalk, C.; Rhodes, J. M.

2001-12-01

Recent isotopic studies on Hawaiian lavas have shown the necessity of constraining fractionation for Pb isotopes. This isotopic system presents systematic variations reflecting the presence of different plume components in the source of Hawaiian basalts. We have analyzed a series of 23 tholeiitic Mauna Loa basalts ranging in age from 36,780 to 140 y for their Pb isotopic compositions by TIMS (Micromass Sector 54) and MC-ICP-MS (Nu Plasma) to directly compare results from the same, carefully leached, samples. These analyses indicate an internal precision better than 120 ppm for the MC-ICP-MS Pb ratios, while for the TIMS ratios, it is in the per mil range. This results in a more coherent dataset for the MC-ICP-MS analyses, with the range of 207Pb/204Pb variations decreasing by a factor of 3 and of 208Pb/204Pb ratios by a factor of 1.5. The co-variations between the Pb isotopic data and other geochemical parameters for the Hawaiian lavas are now much stronger and better defined. There are clearly two groups amongst the prehistoric Mauna Loa basalts: one group with higher 87Sr/86Sr (>0.7038) and low 206Pb/204Pb (<18.15) that covers the entire range of Nb/Y (0.31 to 0.51) observed in this volcano, and the other group with low 87Sr/86Sr (<0.7038) and higher 206Pb/204Pb with Nb/Y<0.4. The second group is only present in basalts younger than 3,000 y or older than 24,000 y. The high 87Sr/86Sr group was not sampled in the HSDP I drill core, which covers an age range of 100,000 y. This either reflects a sampling bias, as the upper flow units (<10,000 y) were not sampled for geochemistry, or variations in magma supply. Altogether, Mauna Loa lava flows that are younger than 20,000 y show much more isotopic variation than older flows and there is a nearly continuous transition away from the Kilauea component. This may indicate that the transition between the Mauna Loa and Mauna Kea trends is not as sharp as previously documented. This study shows the importance of reducing the error associated with mass fractionation by measuring Pb isotopes by MC-ICP-MS to constrain plume components in the mantle source of oceanic basalts.

Major, trace element and isotope geochemistry (Sr-Nd-Pb) of interplinian magmas from Mt. Somma-Vesuvius (Southern Italy)

USGS Publications Warehouse

Somma, R.; Ayuso, R.A.; de Vivo, B.; Rolandi, G.

2001-01-01

Major, trace element and isotopic (Sr, Nd, Pb) data are reported for representative samples of interplinian (Protohistoric, Ancient Historic and Medieval Formations) activity of Mt. Somma-Vesuvius volcano during the last 3500 years. Tephra and lavas exhibit significant major, trace element and isotopic variations. Integration of these data with those obtained by previous studies on the older Somma suites and on the latest activity, allows to better trace a complete petrological and geochemical evolution of the Mt. Somma-Vesuvius magmatism. Three main groups of rocks are recognized. A first group is older than 12.000 yrs, and includes effusive-explosive activity of Mt. Somma. The second group (8000-2700 yrs B.P.) includes the products emitted by the Ottaviano (8000 yrs. B.P.) and Avellino (3550 yrs B.P.) plinian eruptions and the interplinian activity associated with the Protohistoric Formation. Ancient Historic Formation (79-472 A.D.), Medieval Formation (472-1139 A.D.) and Recent interplinian activity (1631-1944 A.D.) belong to the third group of activity (79-1944 A.D.). The three groups of rocks display distinct positive trends of alkalis vs. silica, which become increasingly steeper with age. In the first group there is an increase in silica and alkalis with time, whereas an opposite tendency is observed in the two younger groups. Systematic variations are also evident among the incompatible (Pb, Zr, Hf, Ta, Th, U, Nb, Rb, Cs, Ba) and compatible elements (Sr, Co, Cr). REE document variable degrees of fractionation, with recent activity displaying higher La/Yb ratios than Medieval and Ancient Historic products with the same degree of evolution. N-MORB normalized multi-element diagrams for interplinian rocks show enrichment in Rb, Th, Nb, Zr and Sm (> *10 N-MORB). Sr isotope ratios are variable, with Protohistoric rocks displaying 87Sr/86Sr= 0.70711-0.70810, Ancient Historic 87Sr/86Sr=0.70665-0.70729, and Medieval 87Sr/86Sr=0.70685-0.70803. Neodymium isotopic compositions in the interplinian rocks show a tendency to become slightly more radiogenic with age, from the Protohistoric (143Nd/144Nd=0.51240-0.51247) to Ancient Historic (143Nd/144Nd=0.51245-0.51251). Medieval interplinian activity (143Nd/144Nd: 0.51250-0.51241) lacks meaningful internal trends. All the interplinian rocks have virtually homogeneous compositions of 207Pb/204Pb and 208Pb/204Pb in acid-leached residues (207Pb/204Pb ???15.633 to 15.687, 208Pb/204Pb ???38.947 to 39.181). Values of 206Pb/204Pb are very distinctive, however, and discriminate among the three interplinian cycles of activity (Protohistoric: 18.929-18.971, Ancient Historic: 19.018-19.088, Medieval: 18.964-19.053). Compositional trends of major, trace element and isotopic compositions clearly demonstrate strong temporal variations of the magma types feeding the Somma-Vesuvius activity. These different trends are unlikely to be related only to low pressure evolutionary processes, and reveal variations of parental melt composition. Geochemical data suggest a three component mixing scheme for the interplinian activity. These involve HIMU-type and DMM-type mantle and Calabrian-type lower crust. Interaction between these components has taken place in the source; however, additional quantitative constraints must be acquired in order to better discriminate between magma characteristics inherited from the sources and those acquired during shallow level evolution.

Formation of multiferroic PbTiO3/PbFe12O19 composite by exceeding the solubility limit of Fe in PbTiO3

NASA Astrophysics Data System (ADS)

Jaffari, G. Hassnain; Bilal, M.; Ur Rahman, Jamil; Lee, Soonil

2017-09-01

PbTiO3/PbFe12O19 composites have been synthesized by keeping the Fe concentration (x) in PbFexTi1-xO3 beyond solubility limit, i.e., x > 0.1% and 5% Pb excess. Both these factors have been successfully utilized to extract Fe doped PbTiO3 tetragonal phase which is composited with Magnetoplumbite (PbFe12O19) phase. A systematic evolution of the tetragonality of the former and improved stoichiometry of the later constituent has been observed. As x increases, emergence of additional Raman mode around 650 cm-1 with Fe addition was observed. Systematic increase in the relative intensity of this mode with x, showed that this mode corresponds to the magnetoplumbite phase. In addition to that resultant composite exhibited noticeable systematic decrease in the value of the energy gap as a function of x. Increasing Fe concentration in PbTiO3 constituent, led to monotonic decrease in c/a and increase in strain experienced by PbTiO3. Increase in the value of the saturation polarization was observed up to x = 0.4, which is identified to be associated with the strain induced by the dopant. A comprehensive magnetic characterization revealed monotonic decrease in magnetization with temperature for all compositions. Finally, we found an anomalous temperature dependent trend in the magnetic coercivity which is explained in terms of low temperature decrease in effective magnetic anisotropy by including magneto-electric coupling. Both constituent phases in the composite being ferroelectric and ferromagnetic at room temperature led to formation of better multiferroic properties and exhibited tunable physical properties with x.

Preparation of hybrid nano biocomposite κ-carrageenan/cellulose nanocrystal/nanoclay

NASA Astrophysics Data System (ADS)

Zakuwan, Siti Zarina; Ahmad, Ishak; Ramli, Nazaruddin

2013-11-01

Biodegradable composites film based on κ-carrageenan and nano particles as filler was prepared to study the mechanical strength of carrageenan composites. Solution casting technique was used to prepare_this biocomposite. Preparation of composite film and nano filler involve two stages, preparation of cellulose nanocrystals (CNC) from kenaf with alkali treatment, bleaching, and hydrolysis followed by the preparation of two types of nano composite. Tensile test was carried on the composite film based on κ-carrageenan with the variation percentage of CNC and nano clay to obtain the optimum CNC and nano clay loading. After that hybrid nano-biocomposite film based on κ-carrageenan with the variation percentage of CNC/nano clay (OMMT) according to optimum value of composite carrageenan/CNC and composite carrageenan/nano clay film was prepared. The effect of nano filler on the mechanical properties of carrageenan films was examined. κ-carrageenan biocomposite increased with the optimum at 4% CNC and nano clay composition. Additional improvement of tensile strength with hybridization of CNC and nanoclay indicated better mechanical properties.

Stable Isotope Systematics in Grasshopper Assemblages Along an Elevation Gradient, Colorado

NASA Astrophysics Data System (ADS)

Kohn, M. J.; Evans, S.; Dean, J.; Nufio, C.

2012-12-01

Insects comprise over three quarters of all animal species, yet studies of body water isotopic composition are limited to only the cockroach, the hoverfly, and chironomid flies. These studies suggest that oxygen and hydrogen isotopic compositions in body water are primarily controlled by dietary water sources, with modification from respiratory and metabolic processes. In particular, outward diffusion of isotopically depleted water vapor through insect spiracles at low humidity enriches residual body water in 18O and 2H (D). Stable isotope compositions (δ18O and δD) also respond to gradients in elevation and humidity, but these influences remain poorly understood. In this study, we measured grasshopper body water and local vegetation isotopic compositions along an elevation gradient in Colorado to evaluate three hypotheses: 1) Insect body water isotopic composition is directly related to food source water composition 2) Water vapor transport alters body water isotopic compositions relative to original diet sources, and 3) Elevation gradients influence isotopic compositions in insect body water. Thirty-five species of grasshopper were collected from 14 locations in Colorado grasslands, ranging in elevation from 450 to 800 meters (n=131). Body water was distilled from previously frozen grasshopper specimens using a vacuum extraction line, furnaces (90 °C), and liquid nitrogen traps. Water samples were then analyzed for δ18O and δD on an LGR Liquid Water Isotope Analyzer, housed in the Department of Geosciences, Boise State University. Grasshopper body water isotopic compositions show wide variation, with values ranging between -76.64‰ to +42.82‰ in δD and -3.06‰ to +26.78‰ in δ18O. Precipitation δ18O values over the entire Earth excluding the poles vary by approximately 30‰, comparable to the total range measured in our single study area. Most grasshopper values deviate from the global meteoric water line relating δ18O and δD in precipitation, consistent with evaporative enrichment in food (plants) due to plant transpiration. However, grasshopper body water from any given location is further enriched in 18O and D relative to food. Isotopic values decrease slightly with increasing elevation, but some specific grasshopper species appear more sensitive to elevation. Overall, evaporative enrichment of 18O and D in this relatively dry environment appears the strongest factors influencing grasshopper compositions.

Variation in photosynthetic and nonphotosynthetic vegetation along edaphic and compositional gradients in northwestern Amazonia

NASA Astrophysics Data System (ADS)

Higgins, M. A.; Asner, G. P.; Perez, E.; Elespuru, N.; Alonso, A.

2014-03-01

Tropical forests vary substantially in aboveground properties such as canopy height, canopy structure, and plant species composition, corresponding to underlying variations in soils and geology. Forest properties are often difficult to detect and map in the field, however, due to the remoteness and inaccessibility of these forests. Spectral mixture analysis of Landsat imagery allows mapping of photosynthetic and nonphotosynthetic vegetation quantities (PV and NPV), corresponding to biophysical properties such as canopy openness, forest productivity, and disturbance. Spectral unmixing has been used for applications ranging from deforestation monitoring to identifying burn scars from past fires, but little is known about variations in PV and NPV in intact rainforest. Here we use spectral unmixing of Landsat imagery to map PV and NPV in northern Amazonia, and to test their relationship to soils and plant species composition. To do this we sampled 117 sites crossing a geological boundary in northwestern Amazonia for soil cation concentrations and plant species composition. We then used the Carnegie Landsat Analysis System to map PV and NPV for these sites from multiple dates of Landsat imagery. We found that soil cation concentrations and plant species composition consistently explain a majority of the variation in remotely sensed PV and NPV values. After combining PV and NPV into a single variable (PV-NPV), we determined that the influence of soil properties on canopy properties was inseparable from the influence of plant species composition. In all cases, patterns in PV and NPV corresponded to underlying geological patterns. Our findings suggest that geology and soils regulate canopy PV and NPV values in intact tropical forest, possibly through changes in plant species composition.

Variation in photosynthetic and nonphotosynthetic vegetation along edaphic and compositional gradients in northwestern Amazonia

NASA Astrophysics Data System (ADS)

Higgins, M. A.; Asner, G. P.; Perez, E.; Elespuru, N.; Alonso, A.

2014-07-01

Tropical forests vary substantially in aboveground properties such as canopy height, canopy structure, and plant species composition, corresponding to underlying variations in soils and geology. Forest properties are often difficult to detect and map in the field, however, due to the remoteness and inaccessibility of these forests. Spectral mixture analysis of Landsat imagery allows mapping of photosynthetic and nonphotosynthetic vegetation quantities (PV and NPV), corresponding to biophysical properties such as canopy openness, forest productivity, and disturbance. Spectral unmixing has been used for applications ranging from deforestation monitoring to identifying burn scars from past fires, but little is known about variations in PV and NPV in intact rainforests. Here we use spectral unmixing of Landsat imagery to map PV and NPV in northern Amazonia, and to test their relationship to soils and plant species composition. To do this we sampled 117 sites crossing a geological boundary in northwestern Amazonia for soil cation concentrations and plant species composition. We then used the Carnegie Landsat Analysis System to map PV and NPV for these sites from multiple dates of Landsat imagery. We found that soil cation concentrations and plant species composition consistently explain a majority of the variation in remotely sensed PV and NPV values. After combining PV and NPV into a single variable (PV-NPV), we determined that the influence of soil properties on canopy properties was inseparable from the influence of plant species composition. In all cases, patterns in PV and NPV corresponded to underlying geological patterns. Our findings suggest that geology and soils regulate canopy PV and NPV values in intact tropical forests, possibly through changes in plant species composition.

Investigation of Carbon Fiber Architecture in Braided Composites Using X-Ray CT Inspection

NASA Technical Reports Server (NTRS)

Rhoads, Daniel J.; Miller, Sandi G.; Roberts, Gary D.; Rauser, Richard W.; Golovaty, Dmitry; Wilber, J. Patrick; Espanol, Malena I.

2017-01-01

During the fabrication of braided carbon fiber composite materials, process variations occur which affect the fiber architecture. Quantitative measurements of local and global fiber architecture variations are needed to determine the potential effect of process variations on mechanical properties of the cured composite. Although non-destructive inspection via X-ray CT imaging is a promising approach, difficulties in quantitative analysis of the data arise due to the similar densities of the material constituents. In an effort to gain more quantitative information about features related to fiber architecture, methods have been explored to improve the details that can be captured by X-ray CT imaging. Metal-coated fibers and thin veils are used as inserts to extract detailed information about fiber orientations and inter-ply behavior from X-ray CT images.

Development of Mullite Substrates and Containers

NASA Technical Reports Server (NTRS)

Sibold, J. D.

1979-01-01

The mullite-molten silicon interaction was evaluated through fabrication of a series of bodies made with variations in density, alumina-silica ratio, and glass-crystalline ratio. The materials were tested in a sessile drop technique. None of the variations stood up to extended exposure to molten silicon sufficiently to be recommended as a container material. However, directional solidification experiments suggest that, under proper conditions, contamination of the silicon by mullite containers can be minimized. To improve an already good thermal expansion match between mullite and silicon, compositional variations were studied. Altering of the alumina-silica ratio was determined to give a continuously varying thermal expansion. A standard mullite composition was selected and substrates 40 x 4 x .040 inches were fabricated. Slotted substrates of various configurations and various compositions were also fabricated.

Acquiring Constraints on Morphosyntactic Variation: Children's Spanish Subject Pronoun Expression

ERIC Educational Resources Information Center

Shin, Naomi Lapidus

2016-01-01

Constraints on linguistic variation are consistent across adult speakers, yielding probabilistic and systematic patterns. Yet, little is known about the development of such patterns during childhood. This study investigates Spanish subject pronoun expression in naturalistic data from 154 monolingual children in Mexico, divided into four age…

Investigating Black ASL: A Systematic Review

ERIC Educational Resources Information Center

Toliver-Smith, Andrea; Gentry, Betholyn

2017-01-01

The authors reviewed the literature regarding linguistic variations seen in American Sign Language. These variations are influenced by region and culture. Features of spoken languages have also influenced sign languages as they intersected, e.g., Black ASL has been influenced by African American English. A literature review was conducted to…

Orthopyroxenes as Recorders of Diogenite Petrogenesis: Nature and Causes of Intragrain Chemical Variability

NASA Astrophysics Data System (ADS)

Papike, J. J.; Spilde, M. N.

1993-07-01

Diogenites can as a first approximation be considered as orthopyroxene cumulates in differentiated asteroids [1]. Orthopyroxene is a very powerful mineral recorder in mafic cumulates as demonstrated by Lambert and Simmons [2], who "inverted" REE data from cores of orthopyroxene crystals to estimate the melt compositions parental to the various cumulate horizons in the Stillwater Complex, Montana. These authors demonstrated that the rims of orthopyroxene grains are enriched in REE relative to cores, most likely because of subsolidus orthopyroxene/trapped melt exchange. These authors also noted the importance of working with elements with slow diffusion rates (e.g., REE) relative to those with rapid diffusion rates (e.g., Fe^2+, Mg). In most diogenites, the primary pyroxene is orthopyroxene, while in Fe- enriched diogenites (e.g., some assemblages in Garland and Yamato 75032 [3]) the primary pyroxene phase is pigeonite. In slowly cooled cumulate assemblages, monoclinic pigeonite inverts to orthopyroxene with complex augite exsolution lamellae, and the trace-element records of the parental magmas are essentially lost. Our recent SIMS studies indicate a strong fractionation of REE into the augite lamellae. Most of the orthopyroxene grains that we examined in our original suite of 13 diogenites have fine (100) augite lamellae. These lamellae can easily be reintegrated with the host orthopyroxene by using a relatively broad EMP or SIMS beam of 15-20 micrometers. In this study, we consider the nature and causes of OPX intragrain chemical variations. Our previous studies [4] showed that Cr and Al showed significant variations among the different diogenites and that specific diogenites trend toward one of several different trajectories on a Cr-Al plot. We also found significant chemical variability in individual OPX grains. To date, we have identified three types of intragrain chemical variations: (1) smooth trends from core to rim, (2) periodic linear variations [e.g., (100) augite lamellae in an OPX host], and (3) relatively random variability (e.g., exsolution of spinel). Figure 1 (an OPX from Garland) provides evidence for smooth core-to-rim diffusion profiles. Iron and Mn increase while Mg and Cr decrease from core to rim. Also, Al remains relatively constant, Si decreases, and Ti shows an increase, near the grain edge, on the core-to-rim traverse. These chemical systematics were likely caused by a reaction between the cumulate OPX grain and trapped melt. The trapped melt was apparently enriched in Fe and Mn and depleted in Cr relative to OPX. In conclusion, postcrystallization resetting of cumulate grain chemical systematics must be carefully assessed before the data can be "inverted" to estimates of parental melt compositions. Acknowledgment: This research was supported by NASA grant NAGW-3347 and the Institute of Meteoritics. References: [1] Shearer C. K. et al. (1993) LPS XXIV, 1289-1290. [2] Lambert D. D. and Simmons E. C. (1987) Am. J. Sci., 287, 1-32. [3] Takeda H. et. al. (1979) Proc. 3rd Symp. Antarc. Met., 82-108. [4] Papike J. J. et. al. (1993) LPS XXIV, 1109-1110. Fig. 1 appears here in the hard copy.

Evaluation of indoor air composition time variation in air-tight occupied spaces during night periods

NASA Astrophysics Data System (ADS)

Markov, Detelin

2012-11-01

This paper presents an easy-to-understand procedure for prediction of indoor air composition time variation in air-tight occupied spaces during the night periods. The mathematical model is based on the assumptions for homogeneity and perfect mixing of the indoor air, the ideal gas model for non-reacting gas mixtures, mass conservation equations for the entire system and for each species, a model for prediction of basal metabolic rate of humans as well as a model for prediction of O2 consumption rate and both CO2 and H2O generation rates by breathing. Time variation of indoor air composition is predicted at constant indoor air temperature for three scenarios based on the analytical solution of the mathematical model. The results achieved reveal both the most probable scenario for indoor air time variation in air-tight occupied spaces as well as the cause for morning tiredness after having a sleep in a modern energy efficient space.

Study of rheological, viscoelastic and vulcanization behavior of sponge EPDM/NR blended nano- composites

NASA Astrophysics Data System (ADS)

Arshad Bashir, M.; Shahid, M.; Ahmed, Riaz; Yahya, A. G.

2014-06-01

In this research paper the effect of blending ratio of natural rubber (NR) with Ethylene Propylene Diene Monomer (EPDM) were investigated. Different samples of EPDM/NR ratio were prepared to study the variation of NR in EPDM on rheology, curing characteristics, tangent δ, and viscosity variation during vulcanization of sponge nano composites.The main aim of present research is to develop elastomeric based sponge composites with the blending ratio of base elastomers along with the carbon nano particles for high energy absorbing and damping applications. The curing characteristics, rheology and viscoelastic nature of the composite is remarkably influenced with the progressive blending ratio of the base elastomeric matrix.

Effects of protein supplements consumed with meals, versus between meals, on resistance training-induced body composition changes in adults: a systematic review.

PubMed

Hudson, Joshua L; Bergia, Robert E; Campbell, Wayne W

2018-06-01

The impact of timing the consumption of protein supplements in relation to meals on resistance training-induced changes in body composition has not been evaluated systematically. The aim of this systematic review was to assess the effect of consuming protein supplements with meals, vs between meals, on resistance training-induced body composition changes in adults. Studies published up to 2017 were identified with the PubMed, Scopus, Cochrane, and CINAHL databases. Two researchers independently screened 2077 abstracts for eligible randomized controlled trials of parallel design that prescribed a protein supplement and measured changes in body composition for a period of 6 weeks or more. In total, 34 randomized controlled trials with 59 intervention groups were included and qualitatively assessed. Of the intervention groups designated as consuming protein supplements with meals (n = 16) vs between meals (n = 43), 56% vs 72% showed an increase in body mass, 94% vs 90% showed an increase in lean mass, 87% vs 59% showed a reduction in fat mass, and 100% vs 84% showed an increase in the ratio of lean mass to fat mass over time, respectively. Concurrently with resistance training, consuming protein supplements with meals, rather than between meals, may more effectively promote weight control and reduce fat mass without influencing improvements in lean mass.

Variable electron correlation in high-quality MBE- and PLD-grown SrRuO3 thin films.

NASA Astrophysics Data System (ADS)

Siemons, Wolter; Koster, Gertjan; Yamamoto, Hideki; Vailionis, Arturas; Geballe, Theodore; Blank, Dave; Beasley, Malcolm

2007-03-01

We show that systematic variations in the degree of correlation can occur within SrRuO3 as a function of disorder/off-stoichiometry. In particular, we find that one source of disorder can be controlled in SrRuO3 thin films by varying the deposition conditions or the deposition technique. Specifically, we clearly demonstrate that variation of vacancies on the ruthenium site gives rise to a variation in correlated behavior as seen in the photoemission spectra (XPS and UPS),. Moreover, the transport properties of our samples are clearly linked to their photoemission spectra, and independently the crystal unit cell parameters. SrRuO3 appears to be a system where these effects can be studied in a more systematic fashion, usually not easily accessible, but we suspect that the underlying physics is generic in complex oxidesWork supported by the DoE BES and EPRI.

Consensus and stratification in the affective meaning of human sociality

PubMed Central

Ambrasat, Jens; von Scheve, Christian; Conrad, Markus; Schauenburg, Gesche; Schröder, Tobias

2014-01-01

We investigate intrasocietal consensus and variation in affective meanings of concepts related to authority and community, two elementary forms of human sociality. Survey participants (n = 2,849) from different socioeconomic status (SES) groups in German society provided ratings of 909 social concepts along three basic dimensions of affective meaning. Results show widespread consensus on these meanings within society and demonstrate that a meaningful structure of socially shared knowledge emerges from organizing concepts according to their affective similarity. The consensus finding is further qualified by evidence for subtle systematic variation along SES differences. In relation to affectively neutral words, high-status individuals evaluate intimacy-related and socially desirable concepts as less positive and powerful than middle- or low-status individuals, while perceiving antisocial concepts as relatively more threatening. This systematic variation across SES groups suggests that the affective meaning of sociality is to some degree a function of social stratification. PMID:24843121

[Trend in potentially avoidable hospitalisations for chronic conditions in Spain].

PubMed

Angulo-Pueyo, Ester; Martínez-Lizaga, Natalia; Ridao-López, Manuel; García-Armesto, Sandra; Bernal-Delgado, Enrique

2016-01-01

To analyse the trend in potentially avoidable hospitalisations (PAH) in frail patients or those with chronic conditions in Spain during the period 2002-2013. An observational, ecological study was conducted to analyse the trend in age-sex standardised rates of PAH affecting six clinical conditions, and their variation, in the 203 health care areas composing the publicly-funded health system in Spain. During the period 2002-2013, overall PAH standardised rates decreased by 35%, but systematic variation remained moderately high, around 13% above that expected by chance. Angina admissions showed the largest reduction, followed by those for asthma and chronic obstructive pulmonary disease. In contrast, the prevalence of admissions for dehydration doubled. Despite the decrease in PAH rates, systematic variation among areas remains, indicating differences in chronic care management that lead to distinct healthcare outcomes. Copyright © 2015 SESPAS. Published by Elsevier Espana. All rights reserved.

Diagnosis of seasonal variations of tropical cyclogenesis over the South China Sea using a genesis potential index

NASA Astrophysics Data System (ADS)

Wang, Lei; Pan, Xiumei

2012-09-01

This study examines the seasonal variations of tropical cyclogenesis over the South China Sea (SCS) using a genesis potential (GP) index developed by Emanuel and Nolan. How different environmental factors (including low-level vorticity, mid-level relative humidity, vertical wind shear, and potential intensity) contribute to these variations is investigated. Composite anomalies of the GP index are produced for the summer and winter monsoons separately. These composites replicate the observed seasonal variations of the observed frequency and location of tropical cyclogenesis over the SCS. The degree of contribution by each factor in different regions is determined quantitatively by producing composites of modified indices in which only one of the contributing factors varies, with the others set to climatology. Over the northern SCS, potential intensity makes the largest contributions to the seasonal variations in tropical cyclogenesis. Over the southern SCS, the low-level relative vorticity plays the primary role in the seasonal modulation of tropical cyclone (TC) genesis frequency, and the vertical wind shear plays the secondary role. Thermodynamic factors play more important roles for the seasonal variations in tropical cyclogenesis over the northern SCS, while dynamic factors are more important in the seasonal modulation of TC genesis frequency over the southern SCS.

Influences of space, soil, nematodes and plants on microbial community composition of chalk grassland soils.

PubMed

Yergeau, Etienne; Bezemer, T Martijn; Hedlund, Katarina; Mortimer, Simon R; Kowalchuk, George A; Van Der Putten, Wim H

2010-08-01

Microbial communities respond to a variety of environmental factors related to resources (e.g. plant and soil organic matter), habitat (e.g. soil characteristics) and predation (e.g. nematodes, protozoa and viruses). However, the relative contribution of these factors on microbial community composition is poorly understood. Here, we sampled soils from 30 chalk grassland fields located in three different chalk hill ridges of Southern England, using a spatially explicit sampling scheme. We assessed microbial communities via phospholipid fatty acid (PLFA) analyses and PCR-denaturing gradient gel electrophoresis (DGGE) and measured soil characteristics, as well as nematode and plant community composition. The relative influences of space, soil, vegetation and nematodes on soil microorganisms were contrasted using variation partitioning and path analysis. Results indicate that soil characteristics and plant community composition, representing habitat and resources, shape soil microbial community composition, whereas the influence of nematodes, a potential predation factor, appears to be relatively small. Spatial variation in microbial community structure was detected at broad (between fields) and fine (within fields) scales, suggesting that microbial communities exhibit biogeographic patterns at different scales. Although our analysis included several relevant explanatory data sets, a large part of the variation in microbial communities remained unexplained (up to 92% in some analyses). However, in several analyses, significant parts of the variation in microbial community structure could be explained. The results of this study contribute to our understanding of the relative importance of different environmental and spatial factors in driving the composition of soil-borne microbial communities. © 2009 Society for Applied Microbiology and Blackwell Publishing Ltd.

Changes in erosion and ocean circulation recorded in the Hf isotopic compositions of North Atlantic and Indian Ocean ferromanganese crusts

USGS Publications Warehouse

Piotrowski, Alexander M.; Lee, Der-Chuen; Christensen, John N.; Burton, Kevin W.; Halliday, Alex N.; Hein, James R.; Günther, Detlef

2000-01-01

High-resolution Hf isotopic records are presented for hydrogenetic Fe–Mn crusts from the North Atlantic and Indian Oceans. BM1969 from the western North Atlantic has previously been shown to record systematically decreasing Nd isotopic compositions from about 60 to ∼4 Ma, at which time both show a rapid decrease to unradiogenic Nd composition, thought to be related to the increasing influence of NADW or glaciation in the northern hemisphere. During the Oligocene, North Atlantic Hf became progressively less radiogenic until in the mid-Miocene (∼15 Ma) it reached +1. It then shifted gradually back to an ϵHf value of +3 at 4 Ma, since when it has decreased rapidly to about −1 at the present day. The observed shifts in the Hf isotopic composition were probably caused by variation in intensity of erosion as glaciation progressed in the northern hemisphere. Ferromanganese crusts SS663 and 109D are from about 5500 m depth in the Indian Ocean and are now separated by ∼2300 km across the Mid-Indian Ridge. They display similar trends in Hf isotopic composition from 20 to 5 Ma, with the more northern crust having a composition that is consistently more radiogenic (by ∼2 ϵHf units). Paradoxically, during the last 20 Ma the Hf isotopic compositions of the two crusts have converged despite increased separation and subsidence relative to the ridge. A correlatable negative excursion at ∼5 Ma in the two records may reflect a short-term increase in erosion caused by the activation of the Himalayan main central thrust. Changes to unradiogenic Hf in the central Indian Ocean after 5 Ma may alternatively have been caused by the expanding influence of NADW into the Mid-Indian Basin via circum-Antarctic deep water or a reduction of Pacific flow through the Indonesian gateway. In either case, these results illustrate the utility of the Hf isotope system as a tracer of paleoceanographic changes, capable of responding to subtle changes in erosional regime not readily resolved using other isotope systems.

The effect of occupational and workplace gender composition on sickness absence.

PubMed

Laaksonen, Mikko; Martikainen, Pekka; Rahkonen, Ossi; Lahelma, Eero

2012-02-01

To examine whether gender composition of the occupation or the workplace is associated with sickness absence, whether the gender composition accounts for the observed female excess in sickness absence, and whether gender composition explains variation in sickness absence rates between occupations and workplaces. Random effects models conducted among Helsinki employees (N = 36,395). Women and men working in women-dominated occupations and workplaces had more short-term (1 to 3 days') sickness absence. Gender composition of the occupation and the workplace partly explained gender differences in short-term but not in intermediate (4 to 14 days') and long-term (>2 weeks') absence. Gender composition also explained variation in short-term sickness absence among occupations and workplaces, but this was partly accounted for by social class, income, and job contract type. The results are consistent with the assumption that short-term sickness absence reflects cultures and norms shaping sickness absence behavior.

Inter-doctor variations in the assessment of functional incapacities by insurance physicians

PubMed Central

2011-01-01

Background The aim of this study was to determine the - largely unexplored - extent of systematic variation in the work disability assessment by Dutch insurance physicians (IPs) of employees on long-term sick leave, and to ascertain whether this variation was associated with the individual characteristics and opinions of IPs. Methods In March 2008 we conducted a survey among IPs on the basis of the 'Attitude - Social norm - self-Efficacy' (ASE) model. We used the ensuing data to form latent variables for the ASE constructs. We then linked the background variables and the measured constructs for IPs (n = 199) working at regional offices (n = 27) to the work disability assessments of clients (n = 83,755) and their characteristics. These assessments were carried out between July 2003 and April 2008. We performed multilevel regression analysis on three important assessment outcomes: No Sustainable Capacity or Restrictions for Working Hours (binominal), Functional Incapacity Score (scale 0-6) and Maximum Work Disability Class (binominal). We calculated Intra Class Correlations (ICCs) at IP level and office level and explained variances (R2) for the three outcomes. A higher ICC reflects stronger systematic variation. Results The ICCs at IP level were approximately 6% for No Sustainable Capacity or Restrictions for Working Hours and Maximum Work Disability Class and 12% for Functional Incapacity Score. Background IP variables and the measured ASE constructs for physicians contributed very little to the variation - at most 1%. The ICCs at office level ranged from 0% to around 1%. The R2 was 11% for No Sustainable Capacity or Restrictions for Working Hours, 19% for Functional Incapacity Score and 37% for Maximum Work Disability Class. Conclusion Our study uncovered small to moderate systematic variations in the outcome of disability assessments in the Netherlands. However, the individual characteristics and opinions of insurance physicians have very little impact on these variations. Our findings provided no indications of other reasons for these variations. They may be related to different work routines or to different views on the workload of a 'normal' employee. If so, they could be reduced by well-developed and comprehensively implemented guidelines. Therefore, further research is needed. PMID:22077926

Physical and Chemical Characterization Of Greater Yam (Dioscorea Alata) And Jack Bean (Canavalia Ensiformis) - Based Composite Flour

NASA Astrophysics Data System (ADS)

Affandi, D. R.; Praseptiangga, D.; Nirmala, F. S.; Sigit Amanto, B.; Atmaka, W.

2017-04-01

Indonesia is a tropical country that has great potential in agriculture. Tubers and legumes as examples of the potential commodities are needed to be more developed. Flour production is one of the best alternatives to be chosen as the downstream stage of the tubers and legumes utilization. Greater yam (Dioscorea alata) and jack bean (Canavalia ensiformis) were used in this study. This study was conducted to determine best formula of composite flour based on physical, chemical, and functional characterization of composite flour produced. Variations of formula used was the ratio of greater yam flour and jack bean flour, which were 85:15 (F1), 70:30 (F2), 55:45 (F3), respectively, and this study was conducted using completely randomized design (CRD). The formula variations didn’t show any significant effect on the water absorption capability, water holding capacity (WHC), oil holding capacity (OHC), swelling power, and starch content of the composite flour. However, the formula variations had a significant influence on the colour, proximate parameters, amylose and amylopectin content, resistant starch content, dietary fibre, total phenol, and antioxidant activity of the composite flour produced. Considering the results of physical, chemical, and functional characteristics of composite flour, formula (F1) was selected as the best composite flour developed from greater yam and jack bean flours.

Understanding the effect of compositions on electronegativity, atomic radius and thermal stability of Mg-Ni-Y amorphous alloy

NASA Astrophysics Data System (ADS)

Deshmukh, A. A.; Kuthe, S. A.; Palikundwar, U. A.

2018-05-01

In the present paper, the consequences of variation in compositions on the electronegativity (ΔX), atomic radius difference (δ) and the thermal stability (ΔTx) of Mg-Ni-Y bulk metallic glasses (BMGs) are evaluated. In order to understand the effect of variation in compositions on ΔX, δ and ΔTx, regression analysis is performed on the experimentally available data. A linear correlation between both δ and ΔX with regression coefficient 0.93 is observed. Further, compositional variation is performed with δ and then it is correlated to the ΔTx by deriving subsequent equations. It is observed that concentration of Mg, Ni and Y are directly proportional to the δ with regression coefficients 0.93, 0.93 and 0.50 respectively. The positive slope of Ni and Y stated that ΔTx will increase if it has more contribution from both Ni and Y. On the other hand negative slope stated that composition of Mg should be selected in such a way that it will have more stability with Ni and Y. The results obtained from mathematical calculations are also tested by regression analysis of ΔTx with the compositions of individual elements in the alloy. These results conclude that there is a strong dependence of ΔTx of the alloy on the compositions of the constituting elements in the alloy.

Prokaryotic nucleotide composition is shaped by both phylogeny and the environment.

PubMed

Reichenberger, Erin R; Rosen, Gail; Hershberg, Uri; Hershberg, Ruth

2015-04-09

The causes of the great variation in nucleotide composition of prokaryotic genomes have long been disputed. Here, we use extensive metagenomic and whole-genome data to demonstrate that both phylogeny and the environment shape prokaryotic nucleotide content. We show that across environments, various phyla are characterized by different mean guanine and cytosine (GC) values as well as by the extent of variation on that mean value. At the same time, we show that GC-content varies greatly as a function of environment, in a manner that cannot be entirely explained by disparities in phylogenetic composition. We find environmentally driven differences in nucleotide content not only between highly diverged environments (e.g., soil, vs. aquatic vs. human gut) but also within a single type of environment. More specifically, we demonstrate that some human guts are associated with a microbiome that is consistently more GC-rich across phyla, whereas others are associated with a more AT-rich microbiome. These differences appear to be driven both by variations in phylogenetic composition and by environmental differences-which are independent of these phylogenetic composition differences. Combined, our results demonstrate that both phylogeny and the environment significantly affect nucleotide composition and that the environmental differences affecting nucleotide composition are far subtler than previously appreciated. © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Workshop on Oxygen in the Terrestrial Planets

NASA Technical Reports Server (NTRS)

2004-01-01

This volume contains abstracts that have been accepted for presentation at the Workshop on Oxygen in the Terrestrial Planets, July 20-23,2004, Santa Fe, New Mexico. The contents include: 1) Experimental Constraints on Oxygen and Other Light Element Partitioning During Planetary Core Formation; 2) In Situ Determination of Fe(3+)/SigmaFe of Spinels by Electron Microprobe: An Evaluation of the Flank Method; 3) The Effect of Oxygen Fugacity on Large-Strain Deformation and Recrystallization of Olivine; 4) Plagioclase-Liquid Trace Element Oxygen Barometry and Oxygen Behaviour in Closed and Open System Magmatic Processes; 5) Core Formation in the Earth: Constraints from Ni and Co; 6) Oxygen Isotopic Compositions of the Terrestrial Planets; 7) The Effect of Oxygen Fugacity on Electrical Conduction of Olivine and Implications for Earth s Mantle; 8) Redox Chemical Diffusion in Silicate Melts: The Impact of the Semiconductor Condition; 9) Ultra-High Temperature Effects in Earth s Magma Ocean: Pt and W Partitioning; 10) Terrestrial Oxygen and Hydrogen Isotope Variations: Primordial Values, Systematics, Subsolidus Effects, Planetary Comparisons, and the Role of Water; 11) Redox State of the Moon s Interior; 12) How did the Terrestrial Planets Acquire Their Water?; 13) Molecular Oxygen Mixing Ratio and Its Seasonal Variability in the Martian Atmosphere; 14) Exchange Between the Atmosphere and the Regolith of Mars: Discussion of Oxygen and Sulfur Isotope Evidence; 15) Oxygen and Hydrogen Isotope Systematics of Atmospheric Water Vapor and Meteoric Waters: Evidence from North Texas; 16) Implications of Isotopic and Redox Heterogeneities in Silicate Reservoirs on Mars; 17) Oxygen Isotopic Variation of the Terrestrial Planets; 18) Redox Exchanges in Hydrous Magma; 19) Hydrothermal Systems on Terrestrial Planets: Lessons from Earth; 20) Oxygen in Martian Meteorites: A Review of Results from Mineral Equilibria Oxybarometers; 21) Non-Linear Fractionation of Oxygen Isotopes Implanted in Lunar Metal Grains: Solar, Lunar or Terrestrial Origin? 22) Isotopic Zoning in the Inner Solar System; 23) Redox Conditions on Small Bodies; 24) Determining the Oxygen Fugacity of Lunar Pyroclastic Glasses Using Vanadium Valence - An Update; 25) Mantle Redox Evolution and the Rise of Atmospheric O2; 26) Variation of Kd for Fe-Mg Exchange Between Olivine and Melt for Compositions Ranging from Alkaline Basalt to Rhyolite; 27) Determining the Partial Pressure of Oxygen (PO,) in Solutions on Mars; 28) The Influence of Oxygen Environment on Kinetic Properties of Silicate Rocks and Minerals; 29) Redox Evolution of Magmatic Systems; 30) The Constancy of Upper Mantlefo, Through Time Inferred from V/Sc Ratios in Basalts: Implications for the Rise in Atmospheric 0 2; 31) Nitrogen Solubility in Basaltic Melt. Effects of Oxygen Fugacity, Melt Composition and Gas Speciation; 32) Oxygen Isotope Anomalies in the Atmospheres of Earth and Mars; 33) The Effect of Oxygen Fugacity on Interdiffusion of Iron and Magnesium in Magnesiowiistite 34) The Calibration of the Pyroxene Eu-Oxybarometer for the Martian Meteorites; 35) The Europium Oxybarometer: Power and Pitfalls; 36) Oxygen Fugacity of the Martian Mantle from PigeoniteMelt Partitioning of Samarium, Europium and Gadolinium; 37) Oxidation-Reduction Processes on the Moon: Experimental Verification of Graphite Oxidation in the Apollo 17 Orange Glasses; 38) Oxygen and Core Formation in the Earth; 39) Geologic Record of the Atmospheric Sulfur Chemistry Before the Oxygenation of the Early Earth s Atmosphere; 40) Comparative Planetary Mineralogy: V/(CrCAl) Systematics in Chromite as an Indicator of Relative Oxygen Fugacity; 41) How Well do Sulfur Isotopes Constrain Oxygen Abundance in the Ancient Atmospheres? 42) Experimental Constraints on the Oxygen Isotope (O-18/ O-16) Fractionation in the Ice vapor and Adsorbant vapor Systems of CO2 at Conditions Relevant to the Surface of Mars; 43) Micro-XANES Measurements on Experimental Spinels andhe Oxidation State of Vanadium in Spinel-Melt Pairs; 44) Testing the Magma Ocean Hypothesis Using Metal-Silicate Partitioning of Te, Se and S; 45) Solubility of Oxygen in Liquid Iron at High Pressure and Consequences for the Early Differentiation of Earth and Mars Metallic Liquid Segregation in Planetesimals; 46) Oxygen Fugacity of Lunar Basalts and the Lunar Mantle. Range of fo2 and the Effectiveness of Oxybarometers; 47) Thermodynamic Study of Dissociation Processes of Molecular Oxygen in Vapor over Oxide Compounds; 48) Oxygen Profile of a Thermo-Haliophilic Community in the Badwater Salt Flat; 49) Oxygen Barometry Using Synchrotron MicroXANES of Vanadium; 50) Mass-Independent Isotopic Fractionation of Sulfur from Sulfides in the Huronian Supergroup, Canada; 51) Mass Independent Isotopes and Applications to Planetary Atmospheres; 52) Electrical Conductivity, Oxygen Fugacity, and Mantle Materials; 53) Crustal Evolution and Maturation on Earth: Oxygen Isotope Evidence; 54) The Oxygen Isotope Composition of the Moon: Implications for Planet Formation; 55) Oxygen Isotope Composition of Eucrites and Implications for the Formation of Crust on the HED Parent Body; and 56) The Role of Water in Determining the Oxygen Isotopic Composition of Planets.

A probabilistic approach to remote compositional analysis of planetary surfaces

USGS Publications Warehouse

Lapotre, Mathieu G.A.; Ehlmann, Bethany L.; Minson, Sarah E.

2017-01-01

Reflected light from planetary surfaces provides information, including mineral/ice compositions and grain sizes, by study of albedo and absorption features as a function of wavelength. However, deconvolving the compositional signal in spectra is complicated by the nonuniqueness of the inverse problem. Trade-offs between mineral abundances and grain sizes in setting reflectance, instrument noise, and systematic errors in the forward model are potential sources of uncertainty, which are often unquantified. Here we adopt a Bayesian implementation of the Hapke model to determine sets of acceptable-fit mineral assemblages, as opposed to single best fit solutions. We quantify errors and uncertainties in mineral abundances and grain sizes that arise from instrument noise, compositional end members, optical constants, and systematic forward model errors for two suites of ternary mixtures (olivine-enstatite-anorthite and olivine-nontronite-basaltic glass) in a series of six experiments in the visible-shortwave infrared (VSWIR) wavelength range. We show that grain sizes are generally poorly constrained from VSWIR spectroscopy. Abundance and grain size trade-offs lead to typical abundance errors of ≤1 wt % (occasionally up to ~5 wt %), while ~3% noise in the data increases errors by up to ~2 wt %. Systematic errors further increase inaccuracies by a factor of 4. Finally, phases with low spectral contrast or inaccurate optical constants can further increase errors. Overall, typical errors in abundance are <10%, but sometimes significantly increase for specific mixtures, prone to abundance/grain-size trade-offs that lead to high unmixing uncertainties. These results highlight the need for probabilistic approaches to remote determination of planetary surface composition.

The SH-SY5Y cell line in Parkinson's disease research: a systematic review.

PubMed

Xicoy, Helena; Wieringa, Bé; Martens, Gerard J M

2017-01-24

Parkinson's disease (PD) is a devastating and highly prevalent neurodegenerative disease for which only symptomatic treatment is available. In order to develop a truly effective disease-modifying therapy, improvement of our current understanding of the molecular and cellular mechanisms underlying PD pathogenesis and progression is crucial. For this purpose, standardization of research protocols and disease models is necessary. As human dopaminergic neurons, the cells mainly affected in PD, are difficult to obtain and maintain as primary cells, current PD research is mostly performed with permanently established neuronal cell models, in particular the neuroblastoma SH-SY5Y lineage. This cell line is frequently chosen because of its human origin, catecholaminergic (though not strictly dopaminergic) neuronal properties, and ease of maintenance. However, there is no consensus on many fundamental aspects that are associated with its use, such as the effects of culture media composition and of variations in differentiation protocols. Here we present the outcome of a systematic review of scientific articles that have used SH-SY5Y cells to explore PD. We describe the cell source, culture conditions, differentiation protocols, methods/approaches used to mimic PD and the preclinical validation of the SH-SY5Y findings by employing alternative cellular and animal models. Thus, this overview may help to standardize the use of the SH-SY5Y cell line in PD research and serve as a future user's guide.

Exoplanets with JWST: degeneracy, systematics and how to avoid them

NASA Astrophysics Data System (ADS)

Barstow, Joanna K.; Irwin, Patrick G. J.; Kendrew, Sarah; Aigrain, Suzanne

2016-07-01

The high sensitivity and broad wavelength coverage of the James Webb Space Telescope will transform the field of exoplanet transit spectroscopy. Transit spectra are inferred from minute, wavelength-dependent variations in the depth of a transit or eclipse as the planet passes in front of or is obscured by its star, and the spectra contain information about the composition, structure and cloudiness of exoplanet atmospheres. Atmospheric retrieval is the preferred technique for extracting information from these spectra, but the process can be confused by astrophysical and instrumental systematic noise. We present results of retrieval tests based on synthetic, noisy JWST spectra, for clear and cloudy planets and active and inactive stars. We find that the ability to correct for stellar activity is likely to be a limiting factor for cloudy planets, as the effects of unocculted star spots may mimic the presence of a scattering slope due to clouds. We discuss the pros and cons of the available JWST instrument combinations for transit spectroscopy, and consider the effect of clouds and aerosols on the spectra. Aerosol high in a planet's atmosphere obscures molecular absorption features in transmission, reducing the information content of spectra in wavelength regions where the cloud is optically thick. We discuss the usefulness of particular wavelength regions for identifying the presence of cloud, and suggest strategies for solving the highly-degenerate retrieval problem for these objects.

Chlorine as a geobarometer for alkaline magmas: Evidence from a systematic study of the eruptions of Mount Somma-Vesuvius

PubMed Central

Balcone-Boissard, H.; Boudon, G.; Cioni, R.; Webster, J. D.; Zdanowicz, G.; Orsi, G.; Civetta, L.

2016-01-01

Defining the magma storage conditions of a volcanic system is a major goal in modern volcanology due to its direct implications for the style of a possible eruption, and thus on the associated risk of any crisis and the necessary management and mitigation strategies. Below 200 MPa and at equivalent depths, the strongly non-ideal behaviour of the H-C-O-S-Cl-F system in the silicate melt causes unmixing of the fluid phase to form an H2O-rich vapour and a hydrosaline phase in equilibrium with the silicate melt, both responsible for buffering the chlorine (Cl) concentration. Following this equilibrium, the Cl concentration in melts may be used as a geobarometer for alkaline magmas. Systematic application of this method to the main explosive eruptions of Mount Somma-Vesuvius highlights two main magma ponding zones, at ~180–200 and ~100 MPa. At these pressures, the maximum pre-eruptive H2O contents for the different magma compositions can be estimated; the results obtained, largely in agreement with the current literature, therefore confirm the validity of the method. The Cl geobarometer may help scientists to define the variation of the magmatic reservoir location through time and thus provide strong constraints on pre-eruptive conditions, which are of utmost importance for volcanic crisis management. PMID:26888358

Crop Damage by Primates: Quantifying the Key Parameters of Crop-Raiding Events

PubMed Central

Wallace, Graham E.; Hill, Catherine M.

2012-01-01

Human-wildlife conflict often arises from crop-raiding, and insights regarding which aspects of raiding events determine crop loss are essential when developing and evaluating deterrents. However, because accounts of crop-raiding behaviour are frequently indirect, these parameters are rarely quantified or explicitly linked to crop damage. Using systematic observations of the behaviour of non-human primates on farms in western Uganda, this research identifies number of individuals raiding and duration of raid as the primary parameters determining crop loss. Secondary factors include distance travelled onto farm, age composition of the raiding group, and whether raids are in series. Regression models accounted for greater proportions of variation in crop loss when increasingly crop and species specific. Parameter values varied across primate species, probably reflecting differences in raiding tactics or perceptions of risk, and thereby providing indices of how comfortable primates are on-farm. Median raiding-group sizes were markedly smaller than the typical sizes of social groups. The research suggests that key parameters of raiding events can be used to measure the behavioural impacts of deterrents to raiding. Furthermore, farmers will benefit most from methods that discourage raiding by multiple individuals, reduce the size of raiding groups, or decrease the amount of time primates are on-farm. This study demonstrates the importance of directly relating crop loss to the parameters of raiding events, using systematic observations of the behaviour of multiple primate species. PMID:23056378

Chlorine as a geobarometer for alkaline magmas: Evidence from a systematic study of the eruptions of Mount Somma-Vesuvius

NASA Astrophysics Data System (ADS)

Balcone-Boissard, H.; Boudon, G.; Cioni, R.; Webster, J. D.; Zdanowicz, G.; Orsi, G.; Civetta, L.

2016-02-01

Defining the magma storage conditions of a volcanic system is a major goal in modern volcanology due to its direct implications for the style of a possible eruption, and thus on the associated risk of any crisis and the necessary management and mitigation strategies. Below 200 MPa and at equivalent depths, the strongly non-ideal behaviour of the H-C-O-S-Cl-F system in the silicate melt causes unmixing of the fluid phase to form an H2O-rich vapour and a hydrosaline phase in equilibrium with the silicate melt, both responsible for buffering the chlorine (Cl) concentration. Following this equilibrium, the Cl concentration in melts may be used as a geobarometer for alkaline magmas. Systematic application of this method to the main explosive eruptions of Mount Somma-Vesuvius highlights two main magma ponding zones, at ~180-200 and ~100 MPa. At these pressures, the maximum pre-eruptive H2O contents for the different magma compositions can be estimated; the results obtained, largely in agreement with the current literature, therefore confirm the validity of the method. The Cl geobarometer may help scientists to define the variation of the magmatic reservoir location through time and thus provide strong constraints on pre-eruptive conditions, which are of utmost importance for volcanic crisis management.

Bacterial and fungal communities and contribution of physicochemical factors during cattle farm waste composting.

PubMed

Huhe; Jiang, Chao; Wu, Yanpei; Cheng, Yunxiang

2017-12-01

During composting, the composition of microbial communities is subject to constant change owing to interactions with fluctuating physicochemical parameters. This study explored the changes in bacterial and fungal communities during cattle farm waste composting and aimed to identify and prioritize the contributing physicochemical factors. Microbial community compositions were determined by high-throughput sequencing. While the predominant phyla in the bacterial and fungal communities were largely consistent during the composting, differences in relative abundances were observed. Bacterial and fungal community diversity and relative abundance varied significantly, and inversely, over time. Relationships between physicochemical factors and microbial community compositions were evaluated by redundancy analysis. The variation in bacterial community composition was significantly related to water-soluble organic carbon (WSOC), and pile temperature and moisture (p < .05), while the largest portions of variation in fungal community composition were explained by pile temperature, WSOC, and C/N (p < .05). These findings indicated that those parameters are the most likely ones to influence, or be influenced by the bacterial and fungal communities. Variation partitioning analyses indicated that WSOC and pile temperature had predominant effects on bacterial and fungal community composition, respectively. Our findings will be useful for improving the quality of cattle farm waste composts. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Defining microbial community composition and seasonal variation in a sewage treatment plant in India using a down-flow hanging sponge reactor.

PubMed

Nomoto, Naoki; Hatamoto, Masashi; Hirakata, Yuga; Ali, Muntjeer; Jayaswal, Komal; Iguchi, Akinori; Okubo, Tsutomu; Takahashi, Masanobu; Kubota, Kengo; Tagawa, Tadashi; Uemura, Shigeki; Yamaguchi, Takashi; Harada, Hideki

2018-05-01

The characteristics of the microbial community in a practical-scale down-flow hanging sponge (DHS) reactor, high in organic matter and sulfate ion concentration, and the seasonal variation of the microbial community composition were investigated. Microorganisms related to sulfur oxidation and reduction (2-27%), as well as Leucobacter (7.50%), were abundant in the reactor. Anaerobic bacteria (27-38% in the first layer) were also in abundance and were found to contribute to the removal of organic matter from the sewage in the reactor. By comparing the Simpson index, the abundance-based coverage estimator (ACE) index, and the species composition of the microbial community across seasons (summer/dry, summer/rainy, autumn/dry, and winter/dry), the microbial community was found to change in composition only during the winter season. In addition to the estimation of seasonal variation, the difference in the microbial community composition along the axes of the DHS reactor was investigated for the first time. Although the abundance of each bacterial species differed along both axes of the reactor, the change of the community composition in the reactor was found to be greater along the vertical axis than the horizontal axis of the DHS reactor.

Fluoropyrimidine and platinum toxicity pharmacogenetics: an umbrella review of systematic reviews and meta-analyses.

PubMed

Campbell, Jared M; Bateman, Emma; Peters, Micah Dj; Bowen, Joanne M; Keefe, Dorothy M; Stephenson, Matthew D

2016-03-01

Fluoropyrimidine (FU) and platinum-based chemotherapies are greatly complicated by their associated toxicities. This umbrella systematic review synthesized all systematic reviews that investigated associations between germline variations and toxicity, with the aim of informing personalized medicine. Systematic reviews are important in pharmacogenetics where false positives are common. Four systematic reviews were identified for FU-induced toxicity and three for platinum. Polymorphisms of DPYD and TYMS, but not MTHFR, were statistically significantly associated with FU-induced toxicity (although only DPYD had clinical significance). For platinum, GSTP1 was found to not be associated with toxicity. This umbrella systematic review has synthesized the best available evidence on the pharmacogenetics of FU and platinum toxicity. It provides a useful reference for clinicians and identifies important research gaps.

Peat decomposability in managed organic soils in relation to land use, organic matter composition and temperature

NASA Astrophysics Data System (ADS)

Bader, Cédric; Müller, Moritz; Schulin, Rainer; Leifeld, Jens

2018-02-01

Organic soils comprise a large yet fragile carbon (C) store in the global C cycle. Drainage, necessary for agriculture and forestry, triggers rapid decomposition of soil organic matter (SOM), typically increasing in the order forest < grassland < cropland. However, there is also large variation in decomposition due to differences in hydrological conditions, climate and specific management. Here we studied the role of SOM composition on peat decomposability in a variety of differently managed drained organic soils. We collected a total of 560 samples from 21 organic cropland, grassland and forest soils in Switzerland, monitored their CO2 emission rates in lab incubation experiments over 6 months at two temperatures (10 and 20 °C) and related them to various soil characteristics, including bulk density, pH, soil organic carbon (SOC) content and elemental ratios (C / N, H / C and O / C). CO2 release ranged from 6 to 195 mg CO2-C g-1 SOC at 10 °C and from 12 to 423 mg g-1 at 20 °C. This variation occurring under controlled conditions suggests that besides soil water regime, weather and management, SOM composition may be an underestimated factor that determines CO2 fluxes measured in field experiments. However, correlations between the investigated chemical SOM characteristics and CO2 emissions were weak. The latter also did not show a dependence on land-use type, although peat under forest was decomposed the least. High CO2 emissions in some topsoils were probably related to the accrual of labile crop residues. A comparison with published CO2 rates from incubated mineral soils indicated no difference in SOM decomposability between these soil classes, suggesting that accumulation of recent, labile plant materials that presumably account for most of the evolved CO2 is not systematically different between mineral and organic soils. In our data set, temperature sensitivity of decomposition (Q10 on average 2.57 ± 0.05) was the same for all land uses but lowest below 60 cm in croplands and grasslands. This, in turn, indicates a relative accumulation of recalcitrant peat in topsoils.

Use of Zn isotopes as a probe of anthropogenic contamination and biogeochemical processes in the Seine River, France

NASA Astrophysics Data System (ADS)

Chen, J.; Gaillardet, J.; Louvat, P.; Birck, J.

2009-05-01

Metal contamination is a major issue of human impact on the aqueous environment. River water is particularly susceptible to contamination for both dissolved and particulate loads, displaying a major challenge in understanding the dominant sources and pathways of metals in polluted drainage basins. Recent improvements in mass spectrometry allow isotopic measurements of "non-traditional" metals (Zn, Cu, Fe, etc.), making their isotopes a new potential device to investigate contamination of metals under dissolved and particulate forms in rivers. We focus here on Zn isotope geochemistry in the largely anthropized Seine River (France). A new protocol of two-column separation of Zn from dilute aqueous solution has been developed and proven to be reproducible and satisfactory for accurate measurement of Zn isotopic ratios in water samples by MC-ICP-MS (2σ = 0.04‰). Preliminary results show a total variation of 0.65‰ for δ66Zn in dissolved phases of the Seine basin, and a light isotope enrichment in anthropogenic sources compared to other water samples. The determined conservative behavior of Zn in river water makes its isotopes an effective probe of anthropogenic contamination. The natural and anthropogenic inputs were clearly identified and calculated based on Zn isotope compositions for dissolved loads. Suspended particular matters (SPM) display different Zn isotope compositions compared to dissolved loads, with a total δ66Zn variation of 0.22‰. Zn concentrations and its isotope compositions in SPM reveal inverse relationships as function of the distance from the headwater and the SPM content for geographical and temporal samples, respectively. The δ66Zn data in SPM are interpreted as reflecting the mixture of natural and anthropogenic particles. The correlation between dissolved and particulate δ66Zn shows that adsorption processes are not the dominant process making Zn enrichment in SPM. We report here for the first time systematic δ66Zn data in waters of a whole river basin, showing Zn isotopes a powerful probe to trace contamination sources and biogeochemical processes in hydrologic systems.

The origin of volatile element depletion in early solar system material: Clues from Zn isotopes in chondrules

NASA Astrophysics Data System (ADS)

Pringle, Emily A.; Moynier, Frédéric; Beck, Pierre; Paniello, Randal; Hezel, Dominik C.

2017-06-01

Volatile lithophile elements are depleted in the different planetary materials to various degrees, but the origin of these depletions is still debated. Stable isotopes of moderately volatile elements such as Zn can be used to understand the origin of volatile element depletions. Samples with significant volatile element depletions, including the Moon and terrestrial tektites, display heavy Zn isotope compositions (i.e. enrichment of 66Zn vs. 64Zn), consistent with kinetic Zn isotope fractionation during evaporation. However, Luck et al. (2005) found a negative correlation between δ66Zn and 1/[Zn] between CI, CM, CO, and CV chondrites, opposite to what would be expected if evaporation caused the Zn abundance variations among chondrite groups. We have analyzed the Zn isotope composition of multiple samples of the major carbonaceous chondrite classes: CI (1), CM (4), CV (2), CO (4), CB (2), CH (2), CK (4), and CK/CR (1). The bulk chondrites define a negative correlation in a plot of δ66Zn vs 1/[Zn], confirming earlier results that Zn abundance variations among carbonaceous chondrites cannot be explained by evaporation. Exceptions are CB and CH chondrites, which display Zn systematics consistent with a collisional formation mechanism that created enrichment in heavy Zn isotopes relative to the trend defined by CI-CK. We further report Zn isotope analyses of chondrite components, including chondrules from Allende (CV3) and Mokoia (CV3), as well as an aliquot of Allende matrix. All chondrules are enriched in light Zn isotopes (∼500 ppm on 66Zn/64Zn) relative to the bulk, contrary to what would be expected if Zn were depleted during evaporation, on the other hand the matrix has a complementary heavy isotope composition. We report sequential leaching experiments in un-equilibrated ordinary chondrites, which show sulfides are isotopically heavy compared to silicates and the bulk meteorite by ca. +0.65 per mil on 66Zn/64Zn. We suggest isotopically heavy sulfides were removed from either chondrules or their precursors, thereby producing the light Zn isotope enrichments in chondrules.

Base compositions of genes encoding alpha-actin and lactate dehydrogenase-A from differently adapted vertebrates show no temperature-adaptive variation in G + C content.

PubMed

Ream, Rachael A; Johns, Glenn C; Somero, George N

2003-01-01

There is a long-standing debate in molecular evolution concerning the putative importance of GC content in adapting the thermal stabilities of DNA and RNA. Most studies of this relationship have examined broad-scale compositional patterns, for example, total GC percentages in genomes and occurrence of GC-rich isochores. Few studies have systematically examined the GC contents of individual orthologous genes from differently thermally adapted species. When this has been done, the emphasis has been on comparing large numbers of genes in only a few species. We have approached the GC-adaptation temperature hypothesis in a different manner by examining patterns of base composition of genes encoding lactate dehydrogenase-A (ldh-a) and alpha-actin (alpha-actin) from 51 species of vertebrates whose adaptation temperatures ranged from -1.86 degrees C (Antarctic fishes) to approximately 45 degrees C (desert reptile). No significant positive correlation was found between any index of GC content (GC content of the entire sequence, GC content of the third codon position [GC(3)], and GC content at fourfold degenerate sites [GC(4)]) and any index of adaptation temperature (maximal, mean, or minimal body temperature). For alpha-actin, slopes of regression lines for all comparisons did not differ significantly from zero. For ldh-a, negative correlations between adaptation temperature and total GC content, GC(3), and GC(4) were observed but were shown to be due entirely to phylogenetic influences (as revealed by independent contrast analyses). This comparison of GC content across a wide range of ectothermic ("cold-blooded") and endothermic ("warm-blooded") vertebrates revealed that frogs of the genus Xenopus, which have commonly been used as a representative cold-blooded species, in fact are outliers among ectotherms for the alpha-actin analyses, raising concern about the appropriateness of choosing these amphibians as representative of ectothermic vertebrates in general. Our study indicates that, whereas GC contents of isochores may show variation among different classes of vertebrates, there is no consistent relationship between adaptation temperature and the percentage of thermal stability-enhancing G + C base pairs in protein-coding genes.

A comparison of chemical compositions of reported altered oceanic crusts and global MORB data set: implication for isotopic heterogeneity of recycled materials

NASA Astrophysics Data System (ADS)

Shimoda, G.; Kogiso, T.

2017-12-01

Chemical composition of altered oceanic crust is one of important constraints to delineate chemical heterogeneity of the mantle. Accordingly, many researchers have been studied to determine bulk chemical composition of altered oceanic crust mainly based on chemical compositions of old oceanic crusts at Site 801 and Site 417/418, and young crust at Site 504 (e.g., Staudigel et al., 1996; Bach et al. 2003; Kuo et al., 2016). Their careful estimation provided reliable bulk chemical compositions of these Sites and revealed common geochemical feature of alteration. To assess effect of recycling of altered oceanic crust on chemical evolution of the mantle, it might be meaningful to discuss whether the reported chemical compositions of altered oceanic crusts can represent chemical composition of globally subducted oceanic crusts. Reported chemical compositions of fresh glass or less altered samples from Site 801, 417/418 and 504 were highly depleted compared to that of global MORB reported by Gale et al. (2013), suggesting that there might be sampling bias. Hence, it could be important to consider chemical difference between oceanic crusts of these three Sites and global MORB to discuss effect of recycling of oceanic crust on isotopic heterogeneity of the mantle. It has been suggested that one of controlling factors of chemical variation of oceanic crust is crustal spreading rate because different degree of partial melting affects chemical composition of magmas produced at a mid-ocean ridge. Crustal spreading rate could also affect intensity of alteration. Namely, oceanic crusts produced at slow-spreading ridges may prone to be altered due to existence of larger displacement faults compared to fast spreading ridges which have relatively smooth topography. Thus, it might be significant to evaluate isotopic evolution of oceanic crusts those were produced at different spreading rates. In this presentation, we will provide a possible chemical variation of altered oceanic crusts based on reported bulk chemical compositions of altered oceanic crusts and global data sets of MORB. On the basis of the chemical variation, we will discuss isotopic evolution of altered oceanic crusts to delineate isotopic variation of recycled oceanic crusts.

Chemical variations within and between the clasts, and the matrix of the Abee enstatite chondrite suggest an impact-based differentiation mechanism

NASA Astrophysics Data System (ADS)

Higgins, Michael D.; Martin, Pierre-Etienne M. C.

2018-01-01

Abee is an enstatite chondrite breccia dominantly composed of kamacite, enstatite, silica, plagioclase, troilite and niningerite. Clasts are up to 220 mm long and vary in shape from angular to rounded. Some clasts are zoned with kamacite-enriched rims that follow the edge of the clast. Spatial compositional variations were examined in a small block to find out more about the petrological processes that produced this rock, particularly the relationship between the clasts, the matrix and the cores/rims of the zoned clasts. Compositional maps produced using a focussed-beam XRF were segmented into clasts and matrix, and rims and cores where possible. Compositions of most clasts, matrix and rim/cores define a simple, linear trend on simple variation diagrams. If it is assumed that all components were derived from an original homogeneous composition then the variation can be explained either by addition of kamacite or by loss of all other phases. Within this overall compositional variation the kamacite content generally increases as follows: matrix < large homogeneous clasts ≈ zoned clast cores < small homogeneous clasts ≈ zoned clast rims. Production of diversity by addition of kamacite to clasts and rim seems to require a complex history as the source cannot have been the current matrix. It is also difficult to produce the observed chemical variations and zoning by partial melting. However, differentiation by removal of all non-metallic phases may result from repeated impacts: Shock waves would deform kamacite whilst fracturing all other phases. The broken grains would then migrate towards the surface of the clasts where they would spall off into the matrix. This process would also lead to the observed rounding of some clasts. We propose that this shock-differentiation process be called 'smithing', as it resembles the ancient process of iron refining.

Micro-organisms behind the pollination scenes: microbial imprint on floral nectar sugar variation in a tropical plant community.

PubMed

Canto, A; Herrera, C M

2012-11-01

Variation in the composition of floral nectar reflects intrinsic plant characteristics as well as the action of extrinsic factors. Micro-organisms, particularly yeasts, represent one extrinsic factor that inhabit the nectar of animal-pollinated flowers worldwide. In this study a 'microbial imprint hypothesis' is formulated and tested, in which it is proposed that natural community-wide variation in nectar sugar composition will partly depend on the presence of yeasts in flowers. Occurrence and density of yeasts were studied microscopically in single-flower nectar samples of 22 animal-pollinated species from coastal xeric and sub-humid tropical habitats of the Yucatán Peninsula, Mexico. Nectar sugar concentration and composition were concurrently determined on the same samples using high-performance liquid chromatography (HPLC) methods. Microscopical examination of nectar samples revealed the presence of yeasts in nearly all plant species (21 out of 22 species) and in about half of the samples examined (51·8 % of total, all species combined). Plant species and individuals differed significantly in nectar sugar concentration and composition, and also in the incidence of nectar yeasts. After statistically controlling for differences between plant species and individuals, nectar yeasts still accounted for a significant fraction of community-wide variance in all nectar sugar parameters considered. Significant yeast × species interactions on sugar parameters revealed that plant species differed in the nectar sugar correlates of variation in yeast incidence. The results support the hypothesis that nectar yeasts impose a detectable imprint on community-wide variation in nectar sugar composition and concentration. Since nectar sugar features influence pollinator attraction and plant reproduction, future nectar studies should control for yeast presence and examine the extent to which microbial signatures on nectar characteristics ultimately have some influence on pollination services in plant communities.

Fabrication and characterization of bolus material using polydimethyl-siloxane

NASA Astrophysics Data System (ADS)

Wiratma Jaya, Gede; Sutanto, Heri

2018-01-01

Bolus has been used in radiotherapy to reduce tissue harm and to increase the superficial dose for skin cancer treatment. Commonly, a bolus is made of melamine in several hospitals. In this research, polydimethyl-siloxane (PDMS) material was used for bolus fabrication. The aims of the study are to investigate bolus density, percentage surface dose and its structural strength for each various composition. In bolus preparation, bolus material used composition variation between PDMS volume and catalyst volume. Composition variation were 20:1, 22:1, 24:1, 26:1, 28:1, 30:1 and 32:1. PDMS and catalyst were mixed by chemical solution deposition method. Bolus was molded by using glass cast with the size of 10 × 10 × 0.5 cm3. Bolus density was analyzed by mass per volume equation, for bolus radiation was examined by the linear accelerator using two electron energy (5 and 7 MeV) and bolus strain and tensile strength were examined by Brookfield CT 3 machine. The results of bolus density were similar with soft tissue density, while the lowest and highest density each variation are 22:1 and 28:1. In general, the use of bolus has increased the surface dose. Percentage of surface dose at 5 MeV energy is higher than 7 MeV energy. The highest percentage of surface dose at 5 MeV energy with 0.5 and 1.0 cm bolus thickness was achieved at composition of 32:1. For strain and tensile strength result, the lowest and highest strain each variation are 22:1 and 28:1, then the lowest and highest tensile strength each variation are 32:1 and 28:1. These results is important to select composition material for bolus fabrication in radiotherapy treatment.

Litter quality versus soil microbial community controls over decomposition: a quantitative analysis

USGS Publications Warehouse

Cleveland, Cory C.; Reed, Sasha C.; Keller, Adrienne B.; Nemergut, Diana R.; O'Neill, Sean P.; Ostertag, Rebecca; Vitousek, Peter M.

2014-01-01

The possible effects of soil microbial community structure on organic matter decomposition rates have been widely acknowledged, but are poorly understood. Understanding these relationships is complicated by the fact that microbial community structure and function are likely to both affect and be affected by organic matter quality and chemistry, thus it is difficult to draw mechanistic conclusions from field studies. We conducted a reciprocal soil inoculum × litter transplant laboratory incubation experiment using samples collected from a set of sites that have similar climate and plant species composition but vary significantly in bacterial community structure and litter quality. The results showed that litter quality explained the majority of variation in decomposition rates under controlled laboratory conditions: over the course of the 162-day incubation, litter quality explained nearly two-thirds (64 %) of variation in decomposition rates, and a smaller proportion (25 %) was explained by variation in the inoculum type. In addition, the relative importance of inoculum type on soil respiration increased over the course of the experiment, and was significantly higher in microcosms with lower litter quality relative to those with higher quality litter. We also used molecular phylogenetics to examine the relationships between bacterial community composition and soil respiration in samples through time. Pyrosequencing revealed that bacterial community composition explained 32 % of the variation in respiration rates. However, equal portions (i.e., 16 %) of the variation in bacterial community composition were explained by inoculum type and litter quality, reflecting the importance of both the meta-community and the environment in bacterial assembly. Taken together, these results indicate that the effects of changing microbial community composition on decomposition are likely to be smaller than the potential effects of climate change and/or litter quality changes in response to increasing atmospheric CO2 concentrations or atmospheric nutrient deposition.

Nucleosynthetic Heterogeneity Controls Vanadium Isotope Variations in Bulk Chondrites

NASA Technical Reports Server (NTRS)

Nielsen, S. G.; Righter, K.; Wu, F.; Owens, J. D.; Prytulak, J.; Burton, K.; Parkinson, I.; Davis, D.

2018-01-01

The vanadium (V) isotope composition of early solar system materials have been hypothesized to be sensitive to high energy irradiation that originated from the young Sun. Vanadium has two isotopes with masses 50 and 51 that have (51)V/(50)V ratio of approximately 410. High energy irradiation produces (50)V from various target isotopes of Ti, Cr and Fe, which would result in light V isotope compositions (expressed as delta (51)V in per mille = 1000 x (((51)V/(50)V(sub sample)/(51)V/(50)V(sub AlfaAesar)) - 1)) relative to a presumably chondritic starting composition. Recently published V isotope data for calcium aluminium inclusions (CAIs) has revealed some very negative values relative to chondrites (by almost -4 per mille) that were indeed interpreted to reflect irradiation processes despite the fact that the studied CAIs all exhibited significant initial abundances of (10)Be, while only a few CAIs displayed light V isotope compositions. It is difficult to relate V isotope variations directly to a singular process because V only possesses two isotopes. Therefore, V isotope variations can principally be produced both mass dependent and independent processes. Mass dependent kinetic stable isotope fractionation is common in CAIs for refractory elements due to partial condensation/evaporation processes. The element strontium (Sr) has an almost identical condensation temperature to V and studies of stable Sr isotope compositions in CAIs reveal both heavy and light values relative to chondrites of several permil. These variations are similar in magnitude to those reported for V isotopes in CAIs, which suggests it is possible that some of the V isotope variation in CAIs could be due to kinetic stable isotope fractionation during condensation/evaporation processes.

Systematic variations in the spectral properties of bright regions on Mars

NASA Technical Reports Server (NTRS)

Murchie, Scott; Mustard, John; Bishop, Janice; Head, James; Pieters, Carle; Erard, Stephane

1992-01-01

The color and albedo of the martian surface define two basic surface units, dark gray material interpreted as relatively unaltered 'rock' and bright reddish material interpreted as weathered 'soil'. Understanding the processes contributing to soil formation first requires assessment of the soil's composition and compositional diversity. We report first results of an investigation of the character and variability of Fe- and water-bearing phases in bright reddish materials using ISM data. We also explore implications of these results for chemical evolution of martian soil. Information on the composition and distribution of bright reddish material comes from three major sources: Viking images, measurements by the XRF and GCMS instruments on the Viking Landers, and spectroscopic data. The XRF experiment found nearly identical, Fe-rich major-element compositions comparable to weathered basalt. Soil water, amounting to approximately 1-3 wt. percent as measured by the GCMS, was liberated mostly by heating to greater than or equal to 350 C, suggesting that it is present in a chemically bound form. Spectroscopic studies have detected ferric oxide, probably hematite, as well as molecular water. However, the identities of major silicate phases have been controversial, with conflicting evidence regarding phyllosilicates. Two main interpretations of this evidence have been proposed: Weathering of basaltic glasses by H2O and CO2 formed a mixture of oxides, salts, and metastable phyllosilicates such as montmorillonite and 'palagonite' formed when basaltic melt contacted ground ice or water. Palagonite is a hydrated basaltic glass containing dispersed ferric oxide, recrystallized in varying degrees to phyllosilicates. Typically it is aphanitic, although some examples contain phenocrysts. In either case, eolian redistribution is thought to have resulted in the material's global homogenization. Imaging spectroscopic data returned by the ISM instrument on Phobos 2 provide a powerful new basis for evaluating the composition and origin of martian soil because they are indicative of the presence and distribution of water- and Fe-bearing phases whose mineralogy is sensitive to the history of chemical weathering.

Interpopulational and seasonal variation in the chemical signals of the lizard Gallotia galloti.

PubMed

García-Roa, Roberto; Megía-Palma, Rodrigo; Ortega, Jesús; Jara, Manuel; López, Pilar; Martín, José

2017-01-01

Communicative traits are strikingly diverse and may vary among populations of the same species. Within a population, these traits may also display seasonal variation. Chemical signals play a key role in the communication of many taxa. However, we still know far too little about chemical communication in some vertebrate groups. In lizards, only a few studies have examined interpopulational variation in the composition of chemical cues and signals and only one study has explored the seasonal effects. Here we sampled three subspecies of the Tenerife lizards ( Gallotia galloti ) and analyze the lipophilic fraction of their femoral gland secretions to characterize the potential interpopulational variation in the chemical signals. In addition, we assessed whether composition of these secretions differed between the reproductive and the non-reproductive season. We analyzed variations in both the overall chemical profile and the abundance of the two main compounds (cholesterol and vitamin E). Our results show interpopulational and seasonal differences in G. gallotia chemical profiles. These findings are in accordance with the high interpopulational variability of compounds observed in lizard chemical signals and show that their composition is not only shaped by selective factors linked to reproductive season.

Attenuated total reflectance spectroscopy of plant leaves: A tool for ecological and botanical studies

USGS Publications Warehouse

Ribeiro da Luz, B.

2006-01-01

??? Attenuated total reflectance (ATR) spectra of plant leaves display complex absorption features related to organic constituents of leaf surfaces. The spectra can be recorded rapidly, both in the field and in the laboratory, without special sample preparation. ??? This paper explores sources of ATR spectral variation in leaves, including compositional, positional and temporal variations. Interspecific variations are also examined, including the use of ATR spectra as a tool for species identification. ??? Positional spectral variations generally reflected the abundance of cutin and the epicuticular wax thickness and composition. For example, leaves exposed to full sunlight commonly showed more prominent cutin- and wax-related absorption features compared with shaded leaves. Adaxial vs. abaxial leaf surfaces displayed spectral variations reflecting differences in trichome abundance and wax composition. Mature vs. young leaves showed changes in absorption band position and intensity related to cutin, polysaccharide, and possibly amorphous silica development on and near the leaf surfaces. ??? Provided that similar samples are compared (e.g. adaxial surfaces of mature, sun-exposed leaves) same-species individuals display practically identical ATR spectra. Using spectral matching procedures to analyze an ATR database containing 117 individuals, including 32 different tree species, 83% of the individuals were correctly identified. ?? The Authors (2006).

Land cover variation and West Nile virus prevalence: Patterns, processes, and implications for disease control

USGS Publications Warehouse

Ezenwa, V.O.; Milheim, L.E.; Coffey, M.F.; Godsey, M.S.; King, R.J.; Guptill, S.C.

2007-01-01

Identifying links between environmental variables and infectious disease risk is essential to understanding how human-induced environmental changes will effect the dynamics of human and wildlife diseases. Although land cover change has often been tied to spatial variation in disease occurrence, the underlying factors driving the correlations are often unknown, limiting the applicability of these results for disease prevention and control. In this study, we described associations between land cover composition and West Nile virus (WNV) infection prevalence, and investigated three potential processes accounting for observed patterns: (1) variation in vector density; (2) variation in amplification host abundance; and (3) variation in host community composition. Interestingly, we found that WNV infection rates among Culex mosquitoes declined with increasing wetland cover, but wetland area was not significantly associated with either vector density or amplification host abundance. By contrast, wetland area was strongly correlated with host community composition, and model comparisons suggested that this factor accounted, at least partially, for the observed effect of wetland area on WNV infection risk. Our results suggest that preserving large wetland areas, and by extension, intact wetland bird communities, may represent a valuable ecosystem-based approach for controlling WNV outbreaks. ?? Mary Ann Liebert, Inc.

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

Raszewski, F; Tommy Edwards, T; David Peeler, D

The Liquid Waste Organization (LWO) has requested that the Savannah River National Laboratory (SRNL) to assess the impact of a 100K gallon decant volume from Tank 40H on the existing sludge-only Sludge Batch 4 (SB4)-Frit 510 flowsheet and the coupled operations flowsheet (SB4 with the Actinide Removal Process (ARP)). Another potential SB4 flowsheet modification of interest includes the addition of 3 wt% sodium (on a calcined oxide basis) to a decanted sludge-only or coupled operations flowsheet. These potential SB4 flowsheet modifications could result in significant compositional shifts to the SB4 system. This paper study provides an assessment of the impactmore » of these compositional changes to the projected glass operating windows and to the variability study for the Frit 510-SB4 system. The influence of the compositional changes on melt rate was not assessed in this study nor was it requested. Nominal Stage paper study assessments were completed using the projected compositions for the various flowsheet options coupled with Frit 510 (i.e., variation was not applied to the sludge and frit compositions). In order to gain insight into the impacts of sludge variation and/or frit variation (due to the procurement specifications) on the projected operating windows, three versions of the Variation Stage assessment were performed: (1) the traditional Variation Stage assessment in which the nominal Frit 510 composition was coupled with the extreme vertices (EVs) of each sludge, (2) an assessment of the impact of possible frit variation (within the accepted frit specification tolerances) on each nominal SB4 option, and (3) an assessment of the impact of possible variation in the Frit 510 composition due to the vendor's acceptance specifications coupled with the EVs of each sludge case. The results of the Nominal Stage assessment indicate very little difference among the various flowsheet options. All of the flowsheets provide DWPF with the possibility of targeting waste loadings (WLs) from the low 30s to the low 40s with Frit 510. In general, the Tank 40H decant has a slight negative impact on the operating window, but DWPF still has the ability to target current WLs (34%) and higher WLs if needed. While the decant does not affect practical WL targets in DWPF, melt rate could be reduced due to the lower Na{sub 2}O content. If true, the addition of 3 wt% Na{sub 2}O to the glass system may regain melt rate, assuming that the source of alkali is independent of the impact on melt rate. Coupled operations with Frit 510 via the addition of ARP to the decanted SB4 flowsheet also appears to be viable based on the projected operating windows. The addition of both ARP and 3 wt% Na{sub 2}O to a decanted Tank 40H sludge may be problematic using Frit 510. Although the Nominal Stage assessments provide reasonable operating windows for the SB4 flowsheets being considered with Frit 510, introduction of potential sludge and/or frit compositional variation does have a negative impact. The magnitude of the impact on the projected operating windows is dependent on the specific flowsheet options as well as the applied variation. The results of the traditional Variation Stage assessments indicate that the three proposed Tank 40H decanted flowsheet options (Case No.2--100K gallon decant, Case No.3--100K gallon decant and 3 wt% Na{sub 2}O addition and Case No.4--100K gallon decant and ARP) demonstrate a relatively high degree of robustness to possible sludge variation over WLs of interest with Frit 510. However, the case where the addition of both ARP and 3 wt% Na{sub 2}O is considered was problematic during the traditional Variation Stage assessment. The impact of coupling the frit specifications with the nominal SB4 flowsheet options on the projected operating windows is highly dependent on whether the upper WLs are low viscosity or liquidus temperature limited in the Nominal Stage assessments. Systems that are liquidus temperature limited exhibit a high degree of robustness to the applied frit and sludge variation, while those that are low viscosity limited show significant reductions (6 percentage points) in the upper WLs that can be obtained. When both frit and sludge variations are applied, the paper study results indicate that DWPF could be severely restricted in terms of projected operating windows for the ARP and Na{sub 2}O addition options. An experimental variability study was not performed using the final SB4 composition and Frit 510 since glasses in the ComPro{trademark} data base were identified that bounded the potential operating window of this system. The bounding ARP case was not considered in that assessment. After the flowsheet cases were identified, an electronic search of ComPro{trademark} identified approximately 12 historical glasses within the compositional regions defined by at least one of the five flowsheet options, but the compositional coverage did not appear adequate to bound all cases.« less

Oceanic δ15N biogeography: a novel top-down approach to examine nutrient dynamics in the equatorial Pacific Ocean

NASA Astrophysics Data System (ADS)

Graham, B. S.; Fry, B.; Popp, B. N.; Allain, V.; Olson, R.; Galvan, F.

2010-12-01

By mapping the δ15N and δ13C values of three top-level pelagic predators, yellowfin (Thunnus albacares), bigeye (T. obesus), and skipjack (Katsuwonus pelamis) tuna throughout the equatorial Pacific Ocean, we demonstrated systematic geographic isotopic variation (up to ~12‰ for the δ15N values) that reflect nutrient dynamics that occur at the base of the food web. Remarkably the variation observed in the δ15N values of the tunas is geographically similar to δ15N values previously reported in surface particulate organic matter and deep-sea sediments in the tropical Pacific. We discuss the mechanisms occurring at the base of the food web that could produce the spatial variability observed in tropical tuna δ15N values. We present a simple Rayleigh fractionation model that can explain much of the spatial structure. We also discuss the temporal stability in the isotopic compositions at the base and top of the food web. Overall, this nitrogen isotope cartography or “isoscapes” suggests nitrogen is tightly retained in the marine food web, up to the top predators, and that the uptake of nitrate from the equatorial upwelling zone, denitrification in the oxygen minimum zones, and nitrogen fixation at the base of the food web play major roles in the observed geographical variation. In addition to providing insight into the nutrient dynamics of the open ocean, these predator isoscapes can begin to be used to characterize regional residency in tropical tunas, which is important for the successful management of tuna fisheries.

Natural variations in the rhenium isotopic composition of meteorites

NASA Astrophysics Data System (ADS)

Liu, R.; Hu, L.; Humayun, M.

2017-03-01

Rhenium is an important element with which to test hypotheses of isotope variation. Historically, it has been difficult to precisely correct the instrumental mass bias in thermal ionization mass spectrometry. We used W as an internal standard to correct mass bias on the MC-ICP-MS, and obtained the first precise δ187Re values ( ±0.02‰, 2SE) for iron meteorites and chondritic metal. Relative to metal from H chondrites, IVB irons are systematically higher in δ187Re by 0.14 ‰. δ187Re for other irons are similar to H chondritic metal, although some individual samples show significant isotope fractionation. Since 185Re has a high neutron capture cross section, the effect of galactic cosmic-ray (GCR) irradiation on δ187Re was examined using correlations with Pt isotopes. The pre-GCR irradiation δ187Re for IVB irons is lower, but the difference in δ187Re between IVB irons and other meteoritic metal remains. Nuclear volume-dependent fractionation for Re is about the right magnitude near the melting point of iron, but because of the refractory and compatible character of Re, a compelling explanation in terms of mass-dependent fractionation is elusive. The magnitude of a nucleosynthetic s-process deficit for Re estimated from Mo and Ru isotopes is essentially unresolvable. Since thermal processing reduced nucleosynthetic effects in Pd, it is conceivable that Re isotopic variations larger than those in Mo and Ru may be present in IVBs since Re is more refractory than Mo and Ru. Thus, the Re isotopic difference between IVBs and other irons or chondritic metal remains unexplained.

Preparation Torque Limit for Composites Joined with Mechanical Fasteners

NASA Technical Reports Server (NTRS)

Thomas, Frank P.; Yi, Zhao

2005-01-01

Current design guidelines for determining torque ranges for composites are based on tests and analysis from isotropic materials. Properties of composites are not taken into account. No design criteria based upon a systematic analytical and test analyses is available. This paper is to study the maximum torque load a composite component could carry prior to any failure. Specifically, the torque-tension tests are conducted. NDT techniques including acoustic emission, thermography and photomicroscopy are also utilized to characterize the damage modes.

Temporal changes in randomness of bird communities across Central Europe.

PubMed

Renner, Swen C; Gossner, Martin M; Kahl, Tiemo; Kalko, Elisabeth K V; Weisser, Wolfgang W; Fischer, Markus; Allan, Eric

2014-01-01

Many studies have examined whether communities are structured by random or deterministic processes, and both are likely to play a role, but relatively few studies have attempted to quantify the degree of randomness in species composition. We quantified, for the first time, the degree of randomness in forest bird communities based on an analysis of spatial autocorrelation in three regions of Germany. The compositional dissimilarity between pairs of forest patches was regressed against the distance between them. We then calculated the y-intercept of the curve, i.e. the 'nugget', which represents the compositional dissimilarity at zero spatial distance. We therefore assume, following similar work on plant communities, that this represents the degree of randomness in species composition. We then analysed how the degree of randomness in community composition varied over time and with forest management intensity, which we expected to reduce the importance of random processes by increasing the strength of environmental drivers. We found that a high portion of the bird community composition could be explained by chance (overall mean of 0.63), implying that most of the variation in local bird community composition is driven by stochastic processes. Forest management intensity did not consistently affect the mean degree of randomness in community composition, perhaps because the bird communities were relatively insensitive to management intensity. We found a high temporal variation in the degree of randomness, which may indicate temporal variation in assembly processes and in the importance of key environmental drivers. We conclude that the degree of randomness in community composition should be considered in bird community studies, and the high values we find may indicate that bird community composition is relatively hard to predict at the regional scale.

Human activities cause distinct dissolved organic matter composition across freshwater ecosystems.

PubMed

Williams, Clayton J; Frost, Paul C; Morales-Williams, Ana M; Larson, James H; Richardson, William B; Chiandet, Aisha S; Xenopoulos, Marguerite A

2016-02-01

Dissolved organic matter (DOM) composition in freshwater ecosystems is influenced by the interactions among physical, chemical, and biological processes that are controlled, at one level, by watershed landscape, hydrology, and their connections. Against this environmental template, humans may strongly influence DOM composition. Yet, we lack a comprehensive understanding of DOM composition variation across freshwater ecosystems differentially affected by human activity. Using optical properties, we described DOM variation across five ecosystem groups of the Laurentian Great Lakes region: large lakes, Kawartha Lakes, Experimental Lakes Area, urban stormwater ponds, and rivers (n = 184 sites). We determined how between ecosystem variation in DOM composition related to watershed size, land use and cover, water quality measures (conductivity, dissolved organic carbon (DOC), nutrient concentration, chlorophyll a), and human population density. The five freshwater ecosystem groups had distinctive DOM composition from each other. These significant differences were not explained completely through differences in watershed size nor spatial autocorrelation. Instead, multivariate partial least squares regression showed that DOM composition was related to differences in human impact across freshwater ecosystems. In particular, urban/developed watersheds with higher human population densities had a unique DOM composition with a clear anthropogenic influence that was distinct from DOM composition in natural land cover and/or agricultural watersheds. This nonagricultural, human developed impact on aquatic DOM was most evident through increased levels of a microbial, humic-like parallel factor analysis component (C6). Lotic and lentic ecosystems with low human population densities had DOM compositions more typical of clear water to humic-rich freshwater ecosystems but C6 was only present at trace to background levels. Consequently, humans are strongly altering the quality of DOM in waters nearby or flowing through highly populated areas, which may alter carbon cycles in anthropogenically disturbed ecosystems at broad scales. © 2015 John Wiley & Sons Ltd.

Human activities cause distinct dissolved organic matter composition across freshwater ecosystems

USGS Publications Warehouse

Williams, Clayton J.; Frost, Paul C.; Morales-Williams, Ana M.; Larson, James H.; Richardson, William B.; Chiandet, Aisha S.; Xenopoulos, Marguerite A.

2016-01-01

Dissolved organic matter (DOM) composition in freshwater ecosystems is influenced by interactions between physical, chemical, and biological processes that are controlled, at one level, by watershed landscape, hydrology, and their connections. Against this environmental template, humans may strongly influence DOM composition. Yet, we lack a comprehensive understanding of DOM composition variation across freshwater ecosystems differentially affected by human activity. Using optical properties, we described DOM variation across five ecosystem groups of the Laurentian Great Lakes Region: large lakes, Kawartha Lakes, Experimental Lakes Area, urban stormwater ponds, and rivers (n = 184 sites). We determined how between ecosystem variation in DOM composition related to watershed size, land use and cover, water quality measures (conductivity, dissolved organic carbon (DOC), nutrient concentration, chlorophyll a), and human population density. The five freshwater ecosystem groups had distinctive DOM composition from each other. These significant differences were not explained completely through differences in watershed size nor spatial autocorrelation. Instead, multivariate partial least squares regression showed that DOM composition was related to differences in human impact across freshwater ecosystems. In particular, urban/developed watersheds with higher human population densities had a unique DOM composition with a clear anthropogenic influence that was distinct from DOM composition in natural land cover and/or agricultural watersheds. This nonagricultural, human developed impact on aquatic DOM was most evident through increased levels of a microbial, humic-like parallel factor analysis component (C6). Lotic and lentic ecosystems with low human population densities had DOM compositions more typical of clear water to humic-rich freshwater ecosystems but C6 was only present at trace to background levels. Consequently, humans are strongly altering the quality of DOM in waters nearby or flowing through highly populated areas, which may alter carbon cycles in anthropogenically disturbed ecosystems at broad scales.

The effects of pressure, temperature and composition on olivine-liquid exchange coefficients

NASA Astrophysics Data System (ADS)

Matzen, A. K.; Wood, B. J.

2017-12-01

It has recently been observed that there is a correlation between trace element (Ni and Mn) concentrations in olivine (ol) phenocrysts and thickness of the lithosphere on which they were erupted [1]. There are a number of potential explanations for this observation: the mantle may have interacted with the Ni-rich core; the trace element concentrations reflect presence of recycled crust in the mantle; or it arises from melting of peridotite at different temperatures (T) and pressures (P). Discriminating between these hypotheses requires accurate models of olivine-silicate liquid (liq) partitioning. The three variables that control the observed variations in experimentally-derived ol-liq partition coefficients are T, P, and the composition of the silicate liquid (and to a lesser extent the olivine composition). However, experiments cannot unambiguously disentangle the effects of these variables. For olivine-saturated liquids at constant P, any change in T results in the crystallization or dissolution of olivine and thus a change in liquid composition, resulting in a correlation between T and silicate liquid composition (note that changing the bulk composition such that olivine saturation occurs at a different T also results in a correlation with composition and T). Alternatively, P and T can be varied in concert such that liquid and olivine compositions remain approximately constant [e.g., 2], resulting in a correlation between T and P. In an attempt to resolve the conflation of T, P and compositional effects we turned to metal (met)-liq partitioning studies. Experiments show that, unlike most other elements, P has a strong effect on the partitioning of Ni between Fe-rich metal and silicate melt. Assuming that the pressure dependence of K_{D, Ni-Fe}^{met-liq} (0-25 GPa) [3] is driven primarily by the changing activities in the silicate melt, we can approximate the effect that pressure will have on K_{D, Ni-Fe}^{ol-liq} as measured by [2], using Kress and Carmichael [4] to calculate Fe3+/Fe2+. We find that the pressure effect should be a significant contributor to the observed systematics of K_{D, Ni-Fe}^{ol-liq} between 1 atm and 3 GPa [2]. [1] Sobolev et al (2007) Science, 316, 412-417, [2] Matzen et al (2017) CMP 172:3, [3] Kegler et al (2008) EPSL 268, 28-40, [4] Kress & Carmichael (1991) CMP 108, 82-92.

Regional aeolian dynamics and sand mixing in the Gran Desierto - Evidence from Landsat Thematic Mapper images

NASA Technical Reports Server (NTRS)

Blount, Grady; Greeley, Ronald; Christensen, Phillip R.; Smith, Milton O.; Adams, John B.

1990-01-01

Mesoscale mapping of spatial variations in sand composition of the Gran Desierto (Sonora, Mexico) was carried out on multispectral Landsat TM images of this region, making it possible to examine the dynamic development of sand sheets and dunes. Compositions determined from remote imagery were found to agree well with samples from selected areas. The sand populations delineated were used to describe the sediment source areas, transport paths, and deposition sites. The image analysis revealed important compositional variations aver large areas that were not readily apparent in the field data.

Development and analysis of composite flour bread.

PubMed

Menon, Lakshmi; Majumdar, Swarnali Dutta; Ravi, Usha

2015-07-01

The study elucidates the effect of utilizing cereal-pulse-fruit seed composite flour in the development and quality analysis of leavened bread. The composite flour was prepared using refined wheat flour (WF), high protein soy flour (SF), sprouted mung bean flour (MF) and mango kernel flour (MKF). Three variations were formulated such as V-I (WF: SF: MF: MKF = 85:5:5:5), V-II (WF: SF: MF: MKF = 70:10:10:10), and V-III (WF: SF: MF: MKF = 60:14:13:13). Pertinent functional, physico-chemical and organoleptic attributes were studied in composite flour variations and their bread preparations. Physical characteristics of the bread variations revealed a percentage decrease in loaf height (14 %) and volume (25 %) and 20 % increase in loaf weight with increased substitution of composite flour. The sensory evaluation of experimental breads on a nine-point hedonic scale revealed that V-I score was 5 % higher than the standard bread. Hence, the present study highlighted the nutrient enrichment of bread on incorporation of a potential waste material mango kernel, soy and sprouted legume. Relevant statistical tests were done to analyze the significance of means for all tested parameters.

Recreating the synthesis of starch granules in yeast

PubMed Central

Pfister, Barbara; Sánchez-Ferrer, Antoni; Diaz, Ana; Lu, Kuanjen; Otto, Caroline; Holler, Mirko; Shaik, Farooque Razvi; Meier, Florence; Mezzenga, Raffaele; Zeeman, Samuel C

2016-01-01

Starch, as the major nutritional component of our staple crops and a feedstock for industry, is a vital plant product. It is composed of glucose polymers that form massive semi-crystalline granules. Its precise structure and composition determine its functionality and thus applications; however, there is no versatile model system allowing the relationships between the biosynthetic apparatus, glucan structure and properties to be explored. Here, we expressed the core Arabidopsis starch-biosynthesis pathway in Saccharomyces cerevisiae purged of its endogenous glycogen-metabolic enzymes. Systematic variation of the set of biosynthetic enzymes illustrated how each affects glucan structure and solubility. Expression of the complete set resulted in dense, insoluble granules with a starch-like semi-crystalline organization, demonstrating that this system indeed simulates starch biosynthesis. Thus, the yeast system has the potential to accelerate starch research and help create a holistic understanding of starch granule biosynthesis, providing a basis for the targeted biotechnological improvement of crops. DOI: http://dx.doi.org/10.7554/eLife.15552.001 PMID:27871361

Neighborhood differences in social capital: a compositional artifact or a contextual construct?

PubMed

Subramanian, S V; Lochner, Kimberly A; Kawachi, Ichiro

2003-03-01

Assessment of social capital at the neighborhood level is often based on aggregating individual perceptions of trust and reciprocity. Individual perceptions, meanwhile, are influenced through a range of individual attributes. This paper examines the socioeconomic and demographic attributes that systematically correlate with individual perception of social capital and determines the extent to which such attributes account for neighborhood differences in social capital. Using improved multilevel modeling procedures, we ascertain the extent to which differences in social capital perception can be ascribed to true neighborhood-level variations. The analysis is based on the 1994-95 Community Survey of the Project on Human Development in Chicago Neighborhoods (PHDCN). The response measure is based on survey respondent's perceptions of whether people in their neighborhood can be trusted. The results suggest that even after accounting for individual demographic (age, sex, race, marital status) and socioeconomic characteristics (income, education), significant neighborhood differences remain in individual perceptions of trust, substantiating the notion of social capital as a true contextual construct.

ERTS data user investigation to develop a multistage forest sampling inventory system

NASA Technical Reports Server (NTRS)

Langley, P. G.; Vanroessel, J. W. (Principal Investigator)

1973-01-01

The author has identified the following significant results. A unique digital timber volume estimation system was developed for use with the MSS CCT tapes. The system was tested on a 64-square mile area in Northern California's Trinity Alps. The outcome of a systematic experiment, in which several possible combinations of bands 5 and 7 and a contrast measure were tried, showed that an estimated gain in precision of 50% can be obtained in a multistage sampling design. The difference between bands 5 and 7 proved to be of special importance for the estimation of biomass in the form of timber volume. In addition, an interpretation model for high flight U2 photographs was developed. A maximum multiple correlation coefficient of 0.74 was obtained for the regression model, explaining 55% of the variation in timber volume as estimated from aerial photos and ground measurments. An interpretation model for MSS color composites is in the testing stage.

A study on dependence of the structural, optical and electrical properties of cadmium lead sulphide thin films on Cd/Pb ratio

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

Nair, Sinitha B., E-mail: sinithanair@gmail.com, E-mail: anithakklm@gmail.com; Abraham, Anitha, E-mail: sinithanair@gmail.com, E-mail: anithakklm@gmail.com; Philip, Rachel Reena, E-mail: reenatara@rediffmail.com

2014-10-15

Cadmium Lead Sulphide thin films with systematic variation in Cd/Pb ratio are prepared at 333K by CBD, adjusting the reagent-molarity, deposition time and pH. XRD exhibits crystalline-amorphous transition as Cd% exceeds Pb%. AFM shows agglomeration of crystallites of size ∼50±5 nm. EDAX assess the composition whereas XPS ascertains the ternary formation, with binding energies of Pb4f{sub 7/2} and 4f{sub 5/2}, Cd3d{sub 5/2} and 3d{sub 3/2} and S2p at 137.03, 141.606, 404.667, 412.133 and 160.218 eV respectively. The optical absorption spectra reveal the variance in the direct allowed band gaps, from 1.57eV to 2.42 eV as Cd/Pb ratio increases from 0.2more » to 2.7, suggesting possibility of band gap engineering in the n-type films.« less

Dynamic properties and damping predictions for laminated plates: High order theories - Timoshenko beam

NASA Astrophysics Data System (ADS)

Diveyev, Bohdan; Konyk, Solomija; Crocker, Malcolm J.

2018-01-01

The main aim of this study is to predict the elastic and damping properties of composite laminated plates. This problem has an exact elasticity solution for simple uniform bending and transverse loading conditions. This paper presents a new stress analysis method for the accurate determination of the detailed stress distributions in laminated plates subjected to cylindrical bending. Some approximate methods for the stress state predictions for laminated plates are presented here. The present method is adaptive and does not rely on strong assumptions about the model of the plate. The theoretical model described here incorporates deformations of each sheet of the lamina, which account for the effects of transverse shear deformation, transverse normal strain-stress and nonlinear variation of displacements with respect to the thickness coordinate. Predictions of the dynamic and damping values of laminated plates for various geometrical, mechanical and fastening properties are presented. Comparison with the Timoshenko beam theory is systematically made for analytical and approximation variants.

A scheme to calculate higher-order homogenization as applied to micro-acoustic boundary value problems

NASA Astrophysics Data System (ADS)

Vagh, Hardik A.; Baghai-Wadji, Alireza

2008-12-01

Current technological challenges in materials science and high-tech device industry require the solution of boundary value problems (BVPs) involving regions of various scales, e.g. multiple thin layers, fibre-reinforced composites, and nano/micro pores. In most cases straightforward application of standard variational techniques to BVPs of practical relevance necessarily leads to unsatisfactorily ill-conditioned analytical and/or numerical results. To remedy the computational challenges associated with sub-sectional heterogeneities various sophisticated homogenization techniques need to be employed. Homogenization refers to the systematic process of smoothing out the sub-structural heterogeneities, leading to the determination of effective constitutive coefficients. Ordinarily, homogenization involves a sophisticated averaging and asymptotic order analysis to obtain solutions. In the majority of the cases only zero-order terms are constructed due to the complexity of the processes involved. In this paper we propose a constructive scheme for obtaining homogenized solutions involving higher order terms, and thus, guaranteeing higher accuracy and greater robustness of the numerical results. We present

Chemometric studies of water quality parameters of Sankarankovil block of Tirunelveli, Tamilnadu.

PubMed

Alagumuthu, G; Rajan, M

2010-09-01

The fluoride concentration in ground water was determined in Sankarankovil block of Tirunelveli district of Tamilnadu (India) where it is the only source of drinking water. Various other water quality parameters such as pH, electrical conductivity total hardness and total alkalinity as well as calcium, magnesium, carbonate, bicarbonate and chloride concentrations were also measured. A systematic calculation of correlation coefficient among different physico-chemical parameters was performed. The analytical results indicated considerable variations among the analyzed samples with respect to their chemical composition. Majority of the samples do not comply with Indian as well as WHO water quality standards. The fluoride concentration in the ground water of these villages varied from 0.66 to 3.84 mg l(-1), causes dental fluorosis among people especially children of these villages. The high and low fluoride containing areas were located using isopleth mapping technique. Overall water quality was found unsatisfactory for drinking purposes without any prior treatment except at few locations out of 50 villages.

Groundwater quality in some villages of Haryana, India: focus on fluoride and fluorosis.

PubMed

Meenakshi; Garg, V K; Kavita; Renuka; Malik, Anju

2004-01-02

The fluoride concentration in underground water was determined in four villages of Jind district of Haryana state (India) where it is the only source of drinking water. Various other water quality parameters such as pH, electrical conductivity, total dissolved salts, total hardness, total alkalinity as well as sodium, potassium, calcium, magnesium, carbonate, bicarbonate, chloride and sulfate concentrations were also measured. A systematic calculation of correlation coefficients among different physico-chemical parameters was performed. The analytical results indicated considerable variations among the analyzed samples with respect to their chemical composition. Majority of the samples do not comply with Indian as well as WHO standards for most of the water quality parameters measured. The fluoride concentration in the underground water of these villages varied from 0.3 to 6.9 mg/l, causing dental fluorosis among people especially children of these villages. Overall water quality was found unsatisfactory for drinking purposes without any prior treatment except at eight locations out of 60.

Compositional variation in the chevkinite group: new data from igneous and metamorphic rocks

USGS Publications Warehouse

Belkin, Harvey E.; MacDonald, R.; Wall, F.; Baginski, B.

2009-01-01

Electron microprobe analyses are presented of chevkinite-group minerals from Canada, USA, Guatemala, Norway, Scotland, Italy and India. The host rocks are metacarbonates, alkaline and subalkaline granitoids, quartz-bearing pegmatites, carbonatite and an inferred K-rich tuff. The analyses extend slightly the range of compositions in the chevkinite group, e.g. the most MgO-rich phases yet recorded, and we report two further examples where La is the dominant cation in the A site. Patchily- zoned crystals from Virginia and Guatemala contain both perrierite and chevkinite compositions. The new and published analyses are used to review compositional variation in minerals of the perrierite subgroup, which can form in a wide range of host rock compositions and over a substantial pressure- temperature range. The dominant substitutions in the various cation sites and a generalized substitution scheme are described.

Matched Comparison Group Design Standards in Systematic Reviews of Early Childhood Interventions.

PubMed

Thomas, Jaime; Avellar, Sarah A; Deke, John; Gleason, Philip

2017-06-01

Systematic reviews assess the quality of research on program effectiveness to help decision makers faced with many intervention options. Study quality standards specify criteria that studies must meet, including accounting for baseline differences between intervention and comparison groups. We explore two issues related to systematic review standards: covariate choice and choice of estimation method. To help systematic reviews develop/refine quality standards and support researchers in using nonexperimental designs to estimate program effects, we address two questions: (1) How well do variables that systematic reviews typically require studies to account for explain variation in key child and family outcomes? (2) What methods should studies use to account for preexisting differences between intervention and comparison groups? We examined correlations between baseline characteristics and key outcomes using Early Childhood Longitudinal Study-Birth Cohort data to address Question 1. For Question 2, we used simulations to compare two methods-matching and regression adjustment-to account for preexisting differences between intervention and comparison groups. A broad range of potential baseline variables explained relatively little of the variation in child and family outcomes. This suggests the potential for bias even after accounting for these variables, highlighting the need for systematic reviews to provide appropriate cautions about interpreting the results of moderately rated, nonexperimental studies. Our simulations showed that regression adjustment can yield unbiased estimates if all relevant covariates are used, even when the model is misspecified, and preexisting differences between the intervention and the comparison groups exist.

VISCOSITY AND BINDER COMPOSITION EFFECTS ON TYROSINASE-BASED CARBON PASTE ELECTRODE FOR DETECTION OF PHENOL AND CATECHOL

EPA Science Inventory

The systematic study of the effect of binder viscosity on the sensitivity of a tyrosinase-based carbon paste electrode (CPE) biosensor for phenol and catechol is reported. Silicon oil binders with similar (polydimethylsiloxane) chemical composition were used to represent a wid...

Construction of Lines of Constant Density and Constant Refractive Index for Ternary Liquid Mixtures.

ERIC Educational Resources Information Center

Tasic, Aleksandar Z.; Djordjevic, Bojan D.

1983-01-01

Demonstrates construction of density constant and refractive index constant lines in triangular coordinate system on basis of systematic experimental determinations of density and refractive index for both homogeneous (single-phase) ternary liquid mixtures (of known composition) and the corresponding binary compositions. Background information,…

Composition of Ragusano cheese during aging.

PubMed

Licitra, G; Campo, P; Manenti, M; Portelli, G; Scuderi, S; Carpino, S; Barbano, D M

2000-03-01

Ragusano cheese is a brine-salted pasta filata cheese. Composition changes during 12 mo of aging were determined. Historically, Ragusano cheese has been aged in caves at 14 to 16 degrees C with about 80 to 90% relative humidity. Cheeses (n = 132) included in our study of block-to-block variation were produced by 20 farmhouse cheese makers in the Hyblean plain region of the Province of Ragusa in Sicily. Mean initial cheese block weight was about 14 kg. The freshly formed blocks of cheese before brine salting contained about 45.35% moisture, 25.3% protein, and 25.4% fat, with a pH of 5.25. As result of the brining and aging process, a natural rind forms. After 12 mo of aging, the cheese contained about 33.6% moisture, 29.2% protein, 30.0% fat, and 4.4% salt with a pH of 5.54, but block-to-block variation was large. Both soluble nitrogen content and free fatty acid (FFA) content increased with age. The pH 4.6 acetate buffer and 12% TCA-soluble nitrogen as a percentage of total nitrogen were 16 and 10.7%, respectively, whereas the FFA content was about 643 mg/100 g of cheese at 180 d. Five blocks of cheese were selected at 180 d for a study of variation within block. Composition variation within block was large; the center had higher moisture and lower salt in moisture content than did the outside. Composition variation within blocks favored more proteolysis and softer texture in the center.

Geochemical differentiation processes for arc magma of the Sengan volcanic cluster, Northeastern Japan, constrained from principal component analysis

NASA Astrophysics Data System (ADS)

Ueki, Kenta; Iwamori, Hikaru

2017-10-01

In this study, with a view of understanding the structure of high-dimensional geochemical data and discussing the chemical processes at work in the evolution of arc magmas, we employed principal component analysis (PCA) to evaluate the compositional variations of volcanic rocks from the Sengan volcanic cluster of the Northeastern Japan Arc. We analyzed the trace element compositions of various arc volcanic rocks, sampled from 17 different volcanoes in a volcanic cluster. The PCA results demonstrated that the first three principal components accounted for 86% of the geochemical variation in the magma of the Sengan region. Based on the relationships between the principal components and the major elements, the mass-balance relationships with respect to the contributions of minerals, the composition of plagioclase phenocrysts, geothermal gradient, and seismic velocity structure in the crust, the first, the second, and the third principal components appear to represent magma mixing, crystallizations of olivine/pyroxene, and crystallizations of plagioclase, respectively. These represented 59%, 20%, and 6%, respectively, of the variance in the entire compositional range, indicating that magma mixing accounted for the largest variance in the geochemical variation of the arc magma. Our result indicated that crustal processes dominate the geochemical variation of magma in the Sengan volcanic cluster.

Medically important differences in snake venom composition are dictated by distinct postgenomic mechanisms

PubMed Central

Casewell, Nicholas R.; Wagstaff, Simon C.; Wüster, Wolfgang; Cook, Darren A. N.; Bolton, Fiona M. S.; King, Sarah I.; Pla, Davinia; Sanz, Libia; Calvete, Juan J.; Harrison, Robert A.

2014-01-01

Variation in venom composition is a ubiquitous phenomenon in snakes and occurs both interspecifically and intraspecifically. Venom variation can have severe outcomes for snakebite victims by rendering the specific antibodies found in antivenoms ineffective against heterologous toxins found in different venoms. The rapid evolutionary expansion of different toxin-encoding gene families in different snake lineages is widely perceived as the main cause of venom variation. However, this view is simplistic and disregards the understudied influence that processes acting on gene transcription and translation may have on the production of the venom proteome. Here, we assess the venom composition of six related viperid snakes and compare interspecific changes in the number of toxin genes, their transcription in the venom gland, and their translation into proteins secreted in venom. Our results reveal that multiple levels of regulation are responsible for generating variation in venom composition between related snake species. We demonstrate that differential levels of toxin transcription, translation, and their posttranslational modification have a substantial impact upon the resulting venom protein mixture. Notably, these processes act to varying extents on different toxin paralogs found in different snakes and are therefore likely to be as important as ancestral gene duplication events for generating compositionally distinct venom proteomes. Our results suggest that these processes may also contribute to altering the toxicity of snake venoms, and we demonstrate how this variability can undermine the treatment of a neglected tropical disease, snakebite. PMID:24927555