Terrestrial cosmogenic nuclide surface exposure dating of the oldest glacial successions in the Himalayan orogen: Ladakh Range, northern India

USGS Publications Warehouse

Owen, L.A.; Caffee, M.W.; Bovard, K.R.; Finkel, R.C.; Sharma, M.C.

2006-01-01

Terrestrial cosmogenic nuclide surface exposure dating of moraine boulders and alluvial fan sediments define the timing of five glacial advances over at least the last five glacial cycles in the Ladakh Range of the Transhimalaya. The glacial stages that have been identified are: the Indus Valley glacial stage, dated at older than 430 ka; the Leh glacial stage occurring in the penultimate glacial cycle or older; the Karglacial stage, occurring during the early part of the last glacial cycle; the Bazgo glacial stage, at its maximum during the middle of the last glacial cycle; and the early Holocene Khalling glacial stage. The exposure ages of the Indus Valley moraines are the oldest observed to date throughout the Himalayan orogen. We observe a pattern of progressively more restricted glaciation during the last five glacial cycles, likely indicating a progressive reduction in the moisture supply necessary to sustain glaciation. A possible explanation is that uplift of Himalayan ranges to the south and/or of the Karakoram Mountains to the west of the region may have effectively blocked moisture supply by the south Asian summer monsoon and mid-latitude westerlies, respectively. Alternatively, this pattern of glaciation may reflect a trend of progressively less extensive glaciation in mountain regions that has been observed globally throughout the Pleistocene. ?? 2006 Geological Society of America.

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

PubMed

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

2014-01-24

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

In Situ Radiometric and Exposure Age Dating of the Martian Surface

NASA Technical Reports Server (NTRS)

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

Emergent Dead Vegetation and Paired Cosmogenic Isotope Constraints on Ice Cap Activity, Baffin Island, Arctic Canada

NASA Astrophysics Data System (ADS)

Pendleton, S.; Miller, G. H.

2014-12-01

Recent summer warming has now raised the equilibrium line above almost all ice caps on Baffin Island, resulting in surface lowering and marginal recession everywhere. As cold-based ice recedes it frequently exposes in situ tundra plants that were living at the time ice expanded across the site. Radiocarbon dates for each plant records when cold summers dropped regional snowline below the site, killing the plants, and snowline remained below the site until the collection date. The kill dates also represent the last time that the climate was warm enough to expose the sampling location. Seventy-six vegetation samples collected in 2013 from the Penny Ice Cap region have been dated, with significant age populations at ~0.5, 1.8, 2.3, and 3.6 ka. The absence of ages around ~1, 2, 3, 4.5, and 5.5 ka suggest periods of either no snowline depression or stability. Sixteen vegetation samples returned ages of >45 ka (2 revisited sites from 2010, 14 new). It is postulated that these radiocarbon dead samples were last exposed during the last interglaciation (~120 ka), the last time climate was as warm as present. In addition to plant collections, bedrock exposures at the ice margins were sampled for 26Al/10Be cosmogenic nuclide dating. Seven samples from and around the Penny Ice cap have returned maximum exposure ages from ~ 0.6-0.9 ma and total histories of ~0.6-1.5 ma. In general, samples from the larger Penny Ice Cap exhibited lower amounts of exposure (~20% of total history) than those samples from smaller, localized ice caps (~55%). Radiocarbon dead sites north of the Penny Ice cap experienced significantly more exposure over their lifetimes than their counterparts east of the Penny Ice cap, suggesting significant differences in local and regional land ice fluctuations over the last 2 million years. Utilizing both the method of in situ moss and 26Al/10Be dating provides new insight into both the recent activity and long-term evolution of ice on Baffin Island. In particular these new data help to shed light on how late Holocene coolings affect both large and small ice bodies and how this behavior is represented in the longer-term burial/exposure record contained within the rock surface.

The post-LGM deglaciation in Central and Southeast Switzerland: New insights from surface exposure dating

NASA Astrophysics Data System (ADS)

Boxleitner, Max; Maisch, Max; Brandova, Dagmar; Egli, Markus; Ochs, Susan Ivy; Christl, Marcus

2017-04-01

The deglaciation of the Alps after the Last Glacial Maximum was not a linear process. Moraines as traces of glacier re-advances show that the climate within the general Late-Pleistocene-warming is characterized by repeated cold intervals. While moraine series resulting from these cold spells have been already described for many Alpine valleys at the beginning of the 20th century, absolute chronologies of the Lateglacial climate and glacier development are still fragmentary. The advent of surface exposure dating as a new absolute dating method some 30 years ago made it possible to directly target the deposition-age of moraines. But still many questions regarding the local-to-regional glacier development and its coupling to the overall climate change remain open. In the framework of my PhD-project we study key sites in Central (Uri) and Southeast (Engadine) Switzerland with the aim to develop an absolute post-LGM chronology. More than 50 rock-samples from boulders of different moraine complexes from both regions have been analyzed using 10Be-surface-expsure-dating. Our results show that especially the Younger Dryas plays not unexpected an important role as a very pronounced cold interval. With our results we will refine the understanding of the glacier development in the Swiss Alps during the Lateglacial and the Holocene and improve estimates of equilibrium lines of altitude (ELA) of glaciers from the LGM to the beginning of the Holocene.

Cosmogenic 10Be and 26Al exposure ages of tors and erratics, Cairngorm Mountains, Scotland: Timescales for the development of a classic landscape of selective linear glacial erosion

USGS Publications Warehouse

Phillips, W.M.; Hall, A.M.; Mottram, R.; Fifield, L.K.; Sugden, D.E.

2006-01-01

The occurrence of tors within glaciated regions has been widely cited as evidence for the preservation of relic pre-Quaternary landscapes beneath protective covers of non-erosive dry-based ice. Here, we test for the preservation of pre-Quaternary landscapes with cosmogenic surface exposure dating of tors. Numerous granite tors are present on summit plateaus in the Cairngorm Mountains of Scotland where they were covered by local ice caps many times during the Pleistocene. Cosmogenic 10Be and 26Al data together with geomorphic relationships reveal that these landforms are more dynamic and younger than previously suspected. Many Cairngorm tors have been bulldozed and toppled along horizontal joints by ice motion, leaving event surfaces on tor remnants and erratics that can be dated with cosmogenic nuclides. As the surfaces have been subject to episodic burial by ice, an exposure model based upon ice and marine sediment core proxies for local glacial cover is necessary to interpret the cosmogenic nuclide data. Exposure ages and weathering characteristics of tors are closely correlated. Glacially modified tors and boulder erratics with slightly weathered surfaces have 10Be exposure ages of about 15 to 43 ka. Nuclide inheritance is present in many of these surfaces. Correction for inheritance indicates that the eastern Cairngorms were deglaciated at 15.6 ?? 0.9 ka. Glacially modified tors with moderate to advanced weathering features have 10Be exposure ages of 19 to 92 ka. These surfaces were only slightly modified during the last glacial cycle and gained much of their exposure during the interstadial of marine Oxygen Isotope Stage 5 or earlier. Tors lacking evidence of glacial modification and exhibiting advanced weathering have 10Be exposure ages between 52 and 297 ka. Nuclide concentrations in these surfaces are probably controlled by bedrock erosion rates instead of discrete glacial events. Maximum erosion rates estimated from 10Be range from 2.8 to 12.0 mm/ka, with an error weighted mean of 4.1 ?? 0.2 mm/ka. Three of these surfaces yield model exposure-plus-burial ages of 295-71+84, 520-141+178, and 626-85+102 ka. A vertical cosmogenic nuclide profile across the oldest sampled tor indicates a long-term emergence rate of 31 ?? 2 mm/ka. These findings show that dry-based ice caps are capable of substantially eroding tors by entraining blocks previously detached by weathering processes. Bedrock surfaces and erratic boulders in such settings are likely to have nuclide inheritance and may yield erroneous (too old) exposure ages. While many Cairngorm tors have survived multiple glacial cycles, rates of regolith stripping and bedrock erosion are too high to permit the widespread preservation of pre-Quaternary rock surfaces. ?? 2005 Elsevier B.V. All rights reserved.

Investigating the Usefulness of Cosmogenic in situ 14C for the Dating of Alluvial Fan Surfaces

NASA Astrophysics Data System (ADS)

Goehring, B. M.; Blisniuk, K.; Moon, S.

2017-12-01

Accurate and unambiguous constraints on the age of alluvial fan surfaces remain one of the ultimate achievements for the application of cosmogenic nuclides exposure dating. Information on the age of a fan is not only useful for understanding the rate of sediment transfer from adjacent hillslopes, but also the displacement of an alluvial fan surface and their incised channels represent one of the clearest markers of long-term (102 - 104 years) slip along faults in many regions. Common nuclides such as 10Be, 26Al, and 36Cl, which are often applied to dating alluvial fans, are hampered by inheritance due to their long half-life as nuclides accumulate during exhumation and transport. Here, we present results from a systematic study investigating the usefulness of the cosmogenic nuclide carbon-14 (14C) from the Ash Wash Fan of the Anza Borrego Desert, California, which is well-dated with both 10Be of amalgamated boulder surfaces and U-series ages from pedogenic carbonates. We sampled individual boulders from multiple fan channel bars, rather than an amalgamation of many boulders from a single fan channel bar. Our new14C results yield a median ± half-interquartile age of 4.7 ± 0.8 ka (n = 4, 1 outlier removed). These results are in excellent agreement with the existing U-series and new p-IR-IRSL chronology (5.2 ± 0.3 ka and 5.5 ± 0.8 ka, respectively), but slightly younger than the previously published 10Be amalgamation date of 7.0 ± 1.0 ka. In contrast, 10Be exposure dates of the same boulder in our study yield a median ± half-interquartile age of 10.9 ± 2.6 ka, which we interpret to be the result of insufficient burial time during transport and/or erosion of the boulder to remove accumulated 10Be. Our results suggest that 14C may be a viable chronometer of alluvial fan surfaces less than ca. 25 ka. Finally, inspired by approaches in the burial dating community, we will also explore the possibility of a paired nuclide isochron approach. Measured 14C and 10Be concentrations display a strong correlation (r2 = 0.9), suggesting there may be gains to be made using a paired nuclide approach; we will explore this relationship further in the presentation.

Long-term slip rate of the southern San Andreas Fault, from 10Be-26Al surface exposure dating of an offset alluvial fan

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

der Woerd, J v; Klinger, Y; Sieh, K

We determine the long-term slip rate of the southern San Andreas Fault in the southeastern Indio Hills using {sup 10}Be and {sup 26}Al isotopes to date an offset alluvial fan surface. Field mapping complemented with topographic data, air photos and satellite images allow to precisely determine piercing points across the fault zone that are used to measure an offset of 565 {+-} 80 m. A total of twenty-six quartz-rich cobbles from three different fan surfaces were collected and dated. The tight cluster of nuclide concentrations from 19 samples out of 20 from the offset fan surface implies a simple exposuremore » history, negligible prior exposure and erosion, and yield an age of 35.5 {+-} 2.5 ka. The long-term slip rate of the San Andreas Fault south of Biskra Palms is thus 15.9 {+-} 3.4 mm/yr. This rate is about 10 mm/yr slower than geological (0-14 ka) and short-term geodetic estimates for this part of the San Andreas Fault implying changes in slip rate or in faulting behavior. This result puts new constraints on the slip rate of the San Jacinto and on the Eastern California Shear Zone for the last 35 ka. Our study shows that more sites along the major faults of southern California need to be targeted to better constrain the slip-rates over different time scales.« less

Dating previously balanced rocks in seismically active parts of California and Nevada

USGS Publications Warehouse

Bell, J.W.; Brune, J.N.; Liu, T.; Zreda, M.; Yount, J.C.

1998-01-01

Precariously balanced boulders that could be knocked down by strong earthquake ground motion are found in some seismically active areas of southern California and Nevada. In this study we used two independent surface-exposure dating techniques - rock-varnish microlamination and cosmogenic 36Cl dating methodologies - to estimate minimum- and maximum-limiting ages, respectively, of the precarious boulders and by inference the elapsed time since the sites were shaken down. The results of the exposure dating indicate that all of the precarious rocks are >10.5 ka and that some may be significantly older. At Victorville and Jacumba, California, these results show that the precarious rocks have not been knocked down for at least 10.5 k.y., a conclusion in apparent conflict with some commonly used probabilistic seismic hazard maps. At Yucca Mountain, Nevada, the ages of the precarious rocks are >10.5 to >27.0 ka, providing an independent measure of the minimum time elapsed since faulting occurred on the Solitario Canyon fault.

Assessing Past Surface Processes Rates Using Feldspar Luminescence

NASA Astrophysics Data System (ADS)

Lamothe, M.

2010-12-01

Luminescence dating methods (OSL) developed over the last decade offer absolute depositional ages for sediments, crystallization ages for volcanic material or firing ages for burnt archaeological materials. When these natural surface events are from well-documented geological sequences of events, the ages can decipher timing as well as intensity of processes rates. The advent of luminescence dating has yielded a unique window on the pace of the erosion-transport-depositional cycle as the event assessed using luminescence is last exposure to sunlight and burial. A unique advantage of luminescence is its universal applicability since the routinely used dosimeters, minerals of quartz and feldspar, are almost ubiquitous on the land surface. Dating applications to sediments are still clouded by low accuracy and near saturation of the natural luminescence level, commonly observed for sediments older than the Last Interglacial. The latter imposes severe constraints in the use of quartz as a reliable dosimeter for any environment beyond the Late Pleistocene. However, in the case of feldspar, if dates are corrected for anomalous fading, ages of ancient surface processes could potentially be obtained up to ca 500 ka. Nevertheless, large uncertainties inherent to older ages may therein limit usefulness to precisely assessing processes rates. Case-studies will be used to highlight the potential and limitation of luminescence to properly assess surface processes rates for a) Holocene and older aeolian sedimentary systems, b) rates of tectonic movement by dating relative sea level changes from moderately stable to highly dynamic coastal areas, and c) albeit at its early stages, processes in volcanism, by means of tephra-extracted feldspar luminescence dating.

Dynamics and timing of paleoglaciation on opposite flanks of the Ikh-Turgen Mountains, Central Asia

NASA Astrophysics Data System (ADS)

Blomdin, Robin; Stroeven, Arjen P.; Harbor, Jonathan M.; Gribenski, Natacha; Caffee, Marc W.; Heyman, Jakob; Rogozhina, Irina; Ivanov, Mikhail N.; Petrakov, Dmitry A.; Walther, Michael; Rudoy, Alexei N.; Zhang, Wei; Alexander, Orkhonselenge; Hättestrand, Clas; Lifton, Nathaniel A.; Jansson, Krister N.

2017-04-01

Spanning a northern sector of continental Central Asia, the Altai Mountains contains a rich record of glaciation. Still, there are few studies reconstructing the dynamics and timing of former glaciers in the region. We investigated the glacial history of two paleoglaciers, residing on opposite flanks of the Ikh-Turgen Mountains, straddling the border between Russia and Mongolia, using a combination of remote sensing, terrain analysis, field investigations and 10Be surface exposure dating. On the eastern side (Mongolia) of Ikh-Turgen, mean arithmetic exposure ages from a latero-frontal moraine indicate deglaciation during Marine Isotope Stage (MIS) 3 (45.3±2.7 ka, n=5) and MIS 2 (22.8±3.5 ka, n=4). These age constraints are consistent with other paleoclimate records from the region. Cold and wet conditions during early MIS 2 and MIS 3 likely triggered glacier expansions but the transition to a drier climate resulted in more restricted paleoglacier extents during MIS 2 than during MIS 3. Well-constrained MIS 3 glacier expansions in Central Asia are rare. We therefore speculate whether the climatic and topographic setting of the eastern flank of the Ikh-Turgen Mountains has allowed for a better preservation potential of these moraines, making them more suitable for surface exposure dating than other regions of Central Asia, or whether MIS 3 moraines occur more widespread but await to be robustly dated. Corresponding surface exposure ages, from the western side (Russia) of Ikh-Turgen, indicate a more complex story with large scatter ( 14-53 ka, n=8) making paleoclimate inference and comparison to other proxies difficult. Owing to their proximity, the paleoglaciers of Ikh-Turgen, should have responded similarly to climate forcing, yet they exhibited distinctly different behaviours. We discuss the connection between paleoglacier dynamics and style of moraine deposition and propose that differences in glacier dynamics caused differences in ice-marginal depositional environments, explaining the scatter in exposure ages on the western side. This study shows the importance of style of deposition in chronological studies of glacial landforms and demonstrates that certain moraine types can be difficult to use as paleoclimate proxies.

HEALTH RISK ISSUES RELATED TO MTBE IN DRINKING WATER

EPA Science Inventory

Despite the attention given to methyl tertiary butyl ether (MTBE) as a contaminant in ground water and surface water, the implications of such contamination for human health have not been clearly established to date. Limitations in the databases for both exposure and health effe...

Effects of the low Earth orbital environment on spacecraft materials

NASA Technical Reports Server (NTRS)

Leger, L. J.

1986-01-01

It is evident from space flights during the last three years that the low Earth orbital (LEO) environment interacts with spacecraft surfaces in significant ways. One manifestation of these interactions is recession of, in particular, organic-polymer-based surfaces presumably due to oxidation by atomic oxygen, the major component of the LEO environment. Three experiments have been conducted on Space Shuttle flights 5, 8 and 41-G to measure reaction rates and the effects of various parameters on reaction rates. Surface recession on these flights indicates reaction efficiencies approximately 3 x 10(-24) cu cm/atoms for unfilled organic polymers. Of the metals, silver and osmium are very reactive. Effects on spacecraft or experiment surfaces can be evaluated using the derived reaction efficiencies and a definition of the total exposure to atomic oxygen. This exposure is obtained using an ambient density model, solar activity data and spacecraft parameters of altitude, attitude and operational date. Oxygen flux on a given surface is obtained from the ambient density and spacecraft velocity and can then be integrated to provide the total exposure or fluence. Such information can be generated using simple computational programs and can be converted to various formats. Overall, the extent of damage is strongly dependent on the type of surface and total exposure time.

Late Quaternary activity of the Ecemiş Fault Zone, Turkey; implications from cosmogenic 36Cl dating of offset alluvial fans

NASA Astrophysics Data System (ADS)

Akif Sarıkaya, Mehmet; Yıldırım, Cengiz; Çiner, Attila

2014-05-01

The Ecemiş Fault Zone is the southernmost segment of the Central Anatolian Fault Zone. The tectonic trough of the fault zone defines the boundary between the Central and Eastern Taurides Ranges. The presence of faulted alluvial fans and colluvium within this trough provide favorable conditions to unravel the Late Quaternary slip-rate of the fault zone by cosmogenic surface exposure dating. In this context, we focused on the main strand of the fault zone and also on the Cevizlik Fault that delimits the mountain front of the Aladaǧlar, Eastern Taurides. Geomorphic mapping and topographic surveying indicate four different alluvial fan levels deposited along the main strand. Our topographic survey reveals 60±5 m horizontal and 18±2 m vertical displacement of the oldest fan surface (AF1) associated with the main strand of the fault zone. We dated the surface of the AF1 with 13 cosmogenic 36Cl samples. Our results indicate that the AF1 surface was abandoned maximum 105.3±1.5 ka ago. Accordingly, we propose 0.57±0.05 mm/yr horizontal and 0.17±0.02 mm/yr vertical mean slip-rates since 100 ka for the main strand. On the other hand, we measured 20±2 m vertical displacement on the colluvium along the Cevizlik Fault. The surface exposure age of the colluvium yielded 21.9±0.3 ka that translates to 0.91±0.09 mm/yr vertical slip-rate for the Cevizlik Fault. Our results reveal significant Quaternary deformation, and low strain rates might indicate very long earthquake recurrence intervals along the fault zone.

Cosmic ray exposure dating with in situ produced cosmogenic 3He: results from young Hawaiian lava flows

USGS Publications Warehouse

Kurz, M.D.; Colodner, D.; Trull, T.W.; Moore, R.B.; O'Brien, K.

1990-01-01

In an effort to determine the in situ production rate of spallation-produced cosmogenic 3He, and evaluate its use as a surface exposure chronometer, we have measured cosmogenic helium contents in a suite of Hawaiian radiocarbon-dated lava flows. The lava flows, ranging in age from 600 to 13,000 years, were collected from Hualalai and Mauna Loa volcanoes on the island of Hawaii. Because cosmic ray surface-exposure dating requires the complete absence of erosion or soil cover, these lava flows were selected specifically for this purpose. The 3He production rate, measured within olivine phenocrysts, was found to vary significantly, ranging from 47 to 150 atoms g-1 yr-1 (normalized to sea level). Although there is considerable scatter in the data, the samples younger than 10,000 years are well-preserved and exposed, and the production rate variations are therefore not related to erosion or soil cover. Data averaged over the past 2000 years indicate a sea-level 3He production rate of 125 ?? 30 atoms g-1 yr-1, which agrees well with previous estimates. The longer record suggests a minimum in sea level normalized 3He production rate between 2000 and 7000 years (55 ?? 15 atoms g-1 yr-1), as compared to samples younger than 2000 years (125 ?? 30 atoms g-1 yr-1), and those between 7000 and 10,000 years (127 ?? 19 atoms g-1 yr-1). The minimum in production rate is similar in age to that which would be produced by variations in geomagnetic field strength, as indicated by archeomagnetic data. However, the production rate variations (a factor of 2.3 ?? 0.8) are poorly determined due to the large uncertainties in the youngest samples and questions of surface preservation for the older samples. Calculations using the atmospheric production model of O'Brien (1979) [35], and the method of Lal and Peters (1967) [11], predict smaller production rate variations for similar variation in dipole moment (a factor of 1.15-1.65). Because the production rate variations, archeomagnetic data, and theoretical estimates are not well determined at present, the relationship between dipole moment and production rate will require further study. Precise determination of the production rate is an important uncertainty in the surface-exposure technique, but the data demonstrate that it is feasible to date samples as young as 600 years of age providing that there has been no erosion or soil cover. Therefore, the technique will have important applications for volcanology, glacial geology, geomorphology and archaeology. ?? 1990.

Timing and nature of alluvial fan development along the Chajnantor Plateau, northern Chile

NASA Astrophysics Data System (ADS)

Cesta, Jason M.; Ward, Dylan J.

2016-11-01

Alluvial systems in the Atacama Desert provide a unique opportunity to elucidate the sedimentary response to climate variability, particularly changes in precipitation, in hyperarid environments. Alluvial fans along the eastern margin of the Salar de Atacama, adjacent to the Chajnantor Plateau in the Atacama Desert of northern Chile, provide an archive of climate-modulated sediment transfer and erosion at an extreme of Earth's climate. Three regional alluvial fan surfaces (Qf1 [oldest] to Qf3 [youngest]) were mapped along the western flank of the Chajnantor Plateau. The alluvial fans were examined with geomorphic and terrestrial cosmogenic 36Cl surface exposure dating methods to define the timing of alluvial fan formation and to determine the role of climatic processes on fan development in a hyperarid environment. Alluvial fans in the study area are comprised of hyperconcentrated flow and boulder-rich debris flow deposits that reflect deposition transitioning between cohesive and noncohesive regimes. Alluvial fan surfaces yield exposure ages that range from 49.6 ± 4.4 to 194 ± 12 ka, while debris flow boulders yield exposure ages ranging from 12.4 ± 2.1 to 229 ± 53 ka. Cosmogenic 36Cl exposure ages indicate that abandonment of alluvial fan surfaces Qf1, Qf2, and Qf3 date to 175 ± 22.6 ka (MIS 6), 134.5 ± 9.18 ka (MIS 6), and 20.07 ± 6.26 ka (MIS 2), respectively. A 36Cl concentration-depth profile through alluvial fan Qf1 suggests a simple depositional history with minimal nuclide inheritance implying relatively rapid aggradation (6 m in ca. 25 kyr) followed by surface abandonment ca. 180-200 ka. Our data support a strong climatic control on alluvial fan evolution in the region, and we propose that the alluvial fans along the margins of the Salar de Atacama form according to the humid model of fan formation.

230Th/U dating of a late Pleistocene alluvial fan along the southern San Andreas fault

USGS Publications Warehouse

Fletcher, Kathryn E.K.; Sharp, Warren D.; Kendrick, Katherine J.; Behr, Whitney M.; Hudnut, Kenneth W.; Hanks, Thomas C.

2010-01-01

U-series dating of pedogenic carbonate-clast coatings provides a reliable, precise minimum age of 45.1 ± 0.6 ka (2σ) for the T2 geomorphic surface of the Biskra Palms alluvial fan, Coachella Valley, California. Concordant ages for multiple subsamples from individual carbonate coatings provide evidence that the 238U-234U-230Th system has remained closed since carbonate formation. The U-series minimum age is used to assess previously published 10Be exposure ages of cobbles and boulders. All but one cobble age and some boulder 10Be ages are younger than the U-series minimum age, indicating that surface cobbles and some boulders were partially shielded after deposition of the fan and have been subsequently exhumed by erosion of fine-grained matrix to expose them on the present fan surface. A comparison of U-series and 10Be ages indicates that the interval between final alluvial deposition on the T2 fan surface and accumulation of dateable carbonate is not well resolved at Biskra Palms; however, the “time lag” inherent to dating via U-series on pedogenic carbonate can be no larger than ∼10 k.y., the uncertainty of the 10Be-derived age of the T2 fan surface. Dating of the T2 fan surface via U-series on pedogenic carbonate (minimum age, 45.1 ± 0.6 ka) and 10Be on boulder-top samples using forward modeling (preferred age, 50 ± 5 ka) provides broadly consistent constraints on the age of the fan surface and helps to elucidate its postdepositional development.

230Th/U dating of a late pleistocene alluvial fan along the southern san andreas fault

USGS Publications Warehouse

Fletcher, K.E.K.; Sharp, W.D.; Kendrick, K.J.; Behr, W.M.; Hudnut, K.W.; Hanks, T.C.

2010-01-01

U-series dating of pedogenic carbonate-clast coatings provides a reliable, precise minimum age of 45.1 ?? 0.6 ka (2??) for the T2 geomorphic surface of the Biskra Palms alluvial fan, Coachella Valley, California. Concordant ages for multiple subsamples from individual carbonate coatings provide evidence that the 238U-234U-230Th system has remained closed since carbonate formation. The U-series minimum age is used to assess previously published 10Be exposure ages of cobbles and boulders. All but one cobble age and some boulder 10Be ages are younger than the U-series minimum age, indicating that surface cobbles and some boulders were partially shielded after deposition of the fan and have been subsequently exhumed by erosion of fine-grained matrix to expose them on the present fan surface. A comparison of U-series and 10Be ages indicates that the interval between final alluvial deposition on the T2 fan surface and accumulation of dateable carbonate is not well resolved at Biskra Palms; however, the "time lag" inherent to dating via U-series on pedogenic carbonate can be no larger than ~10 k.y., the uncertainty of the 10Be-derived age of the T2 fan surface. Dating of the T2 fan surface via U-series on pedogenic carbonate (minimum age, 45.1 ?? 0.6 ka) and 10Be on boulder-top samples using forward modeling (preferred age, 50 ?? 5 ka) provides broadly consistent constraints on the age of the fan surface and helps to elucidate its postdepositional development. ?? 2010 Geological Society of America.

Precise Surface Exposure Dating of Early Holocene and Little Ice Age Moraines in the Cordillera Vilcabamba of Southern Peru

NASA Astrophysics Data System (ADS)

Licciardi, J. M.; Schaefer, J. M.; Lund, D. C.; Taggart, J. R.

2008-12-01

We have established precise ages of two glacial events in the tropical Andean highlands of southern Peru. The field site is located on the flanks of Nevado Salcantay (6271 m asl; 13°20'S latitude), the highest peak in the Cordillera Vilcabamba. A two-fold sequence of nested lateral and end moraines was mapped in a glacial trough emanating from the south face of Salcantay. Well-defined outer and inner moraines were deposited by valley glaciers that terminated 5 km and 3 km, respectively, from their head on the Salcantay massif. Cosmogenic 10Be surface exposure dating of boulders on the outer (n = 7) and inner (n = 7) moraine crests expands upon initial age control for these deposits and improves substantially on the precision of earlier 10Be measurements. The new results yield mean ages of 9.0 ± 0.3 ka for the outer moraine and 195 ± 24 years for the inner moraine, corresponding to glacial events during the early and latest Holocene. These ages are derived using the CRONUS-Earth 10Be exposure age calculator with Lal-Stone production rate scaling and the default height-pressure relationship. The inner moraine age correlates with the timing of the Little Ice Age as defined from northern mid- and high latitude records, and indicates considerable expansion of glaciers heading on Nevado Salcantay during this climatic minimum. Recent geomorphic mapping has identified similar sequences of moraines in adjacent drainages on and near Salcantay, suggesting a broader regional signal of two prominent Holocene glacial events in this segment of the southern Peruvian Andes; 10Be dating of these additional moraines is underway. Our new glacier chronologies complement ice core and lacustrine paleoclimate records in the vicinity, thereby increasing spatial and temporal coverage for identifying patterns of climate change in the tropical Andes during the Holocene. Apart from their paleoclimatic significance, the results also demonstrate a newly- developed capability of 10Be exposure dating for establishing high-resolution chronologies from historical glacial deposits.

Surface-exposure ages of Front Range moraines that may have formed during the Younger Dryas, 8.2 cal ka, and Little Ice Age events

USGS Publications Warehouse

Benson, L.; Madole, R.; Kubik, P.; McDonald, R.

2007-01-01

Surface-exposure (10Be) ages have been obtained on boulders from three post-Pinedale end-moraine complexes in the Front Range, Colorado. Boulder rounding appears related to the cirque-to-moraine transport distance at each site with subrounded boulders being typical of the 2-km-long Chicago Lakes Glacier, subangular boulders being typical of the 1-km-long Butler Gulch Glacier, and angular boulders being typical of the few-hundred-m-long Isabelle Glacier. Surface-exposure ages of angular boulders from the Isabelle Glacier moraine, which formed during the Little Ice Age (LIA) according to previous lichenometric dating, indicate cosmogenic inheritance values ranging from 0 to ???3.0 10Be ka.11Surface-exposure ages in this paper are labeled 10Be; radiocarbon ages are labeled 14C ka, calendar and calibrated radiocarbon ages are labeled cal ka, and layer-based ice-core ages are labeled ka. 14C ages, calibrated 14C ages, and ice core ages are given relative to AD 1950, whereas 10Be ages are given relative to the sampling date. Radiocarbon ages were calibrated using CALIB 5.01 and the INTCAL04 data base Stuiver et al. (2005). Ages estimated using CALIB 5.01 are shown in terms of their 1-sigma range. Subangular boulders from the Butler Gulch end moraine yielded surface-exposure ages ranging from 5 to 10.2 10Be ka. We suggest that this moraine was deposited during the 8.2 cal ka event, which has been associated with outburst floods from Lake Agassiz and Lake Ojibway, and that the large age range associated with the Butler Gulch end moraine is caused by cosmogenic shielding of and(or) spalling from boulders that have ages in the younger part of the range and by cosmogenic inheritance in boulders that have ages in the older part of the range. The surface-exposure ages of eight of nine subrounded boulders from the Chicago Lakes area fall within the 13.0-11.7 10Be ka age range, and appear to have been deposited during the Younger Dryas interval. The general lack of inheritance in the eight samples probably stems from the fact that only a few thousand years intervened between the retreat of the Pinedale glacier and the advance of the Chicago Lakes glacier; in addition, bedrock in the Chicago Lakes cirque area may have remained covered with snow and ice during that interval, thus partially shielding the bedrock from cosmogenic radiation.

Age evaluation and causation of rock-slope failures along the western margin of the Antrim Lava Group (ALG), Northern Ireland, based on cosmogenic isotope (36Cl) surface exposure dating

NASA Astrophysics Data System (ADS)

Southall, David W.; Wilson, Peter; Dunlop, Paul; Schnabel, Christoph; Rodés, Ángel; Gulliver, Pauline; Xu, Sheng

2017-05-01

The temporal pattern of postglacial rock-slope failure in a glaciated upland area of Ireland (the western margin of the Antrim Lava Group) was evaluated using both 36Cl exposure dating of surface boulders on run-out debris and 14C dating of basal organic soils from depressions on the debris. The majority of the 36Cl ages ( 21-15 ka) indicate that major failures occurred during or immediately following local deglaciation ( 18-17 ka). Other ages ( 14-9 ka) suggest some later, smaller-scale failures during the Lateglacial and/or early Holocene. The 14C ages (2.36-0.15 cal ka BP) indicate the very late onset of organic accumulation and do not provide close limiting age constraints. Rock-slope failure during or immediately following local deglaciation was probably in response to some combination of glacial debuttressing, slope steepening and paraglacial stress release. Later failures may have been triggered by seismic activity associated with glacio-isostatic crustal uplift and/or permafrost degradation consequent upon climate change. The 36Cl ages support the findings of previous studies that show the deglacial - Lateglacial period in northwest Ireland and Scotland to have been one of enhanced rock-slope failure. Table S2 Concentrations of main elements (as oxides) etc.

Numerical dating of a Late Quaternary spit-shoreline complex at the northern end of Silver Lake playa, Mojave Desert, California: A comparison of the applicability of radiocarbon, luminescence, terrestrial cosmogenic nuclide, electron spin resonance, U-series and amino acid racemization methods

USGS Publications Warehouse

Owen, L.A.; Bright, Jordon; Finkel, R.C.; Jaiswal, M.K.; Kaufman, D.S.; Mahan, S.; Radtke, U.; Schneider, J.S.; Sharp, W.; Singhvi, A.K.; Warren, C.N.

2007-01-01

A Late Quaternary spit-shoreline complex on the northern shore of Pleistocene Lake Mojave of southeastern California, USA was studied with the goal of comparing accelerator mass spectrometry (AMS) radiocarbon, luminescence, electron spin resonance (ESR), terrestrial cosmogenic radionuclide (TCN) surface exposure, amino acid racemization (AAR) and U-series dating methods. The pattern of ages obtained by the different methods illustrates the complexity of processes acting in the lakeshore environment and highlights the utility of a multi-method approach. TCN surface exposure ages (mostly ???20-30 ka) record the initial erosion of shoreline benches, whereas radiocarbon ages on shells (determined in this and previous studies) within the spit, supported by AAR data, record its construction at fluctuating lake levels from ???16 to 10 ka. Luminescence ages on spit sediment (???6-7 ka) and ESR ages on spit shells (???4 ka) are anomalously young relative to radiocarbon ages of shells within the same deposits. The significance of the surprisingly young luminescence ages is not clear. The younger ESR ages could be a consequence of post-mortem enrichment of U in the shells. High concentrations of detrital thorium in tufa coating spit gravels inhibited the use of single-sample U-series dating. Detailed comparisons such as this provide one of the few means of assessing the accuracy of Quaternary dating techniques. More such comparisons are needed. ?? 2007 Elsevier Ltd and INQUA.

Timing of Expansions of the Quelccaya Ice Cap, Peru, and Implications for Cosmogenic Nuclide Production Rate Calibration

NASA Astrophysics Data System (ADS)

Lowell, T. V.; Kelly, M. A.; Applegate, P. J.; Smith, C. A.; Phillips, F. M.; Hudson, A. M.

2010-12-01

We calibrate the production rate of the cosmogenic nuclide beryllium-10 (10Be) at a low-latitude, high-elevation site, using nuclide concentrations measured in moraine boulders and an independent chronology determined with bracketing radiocarbon dates. The measurement of terrestrial cosmogenic nuclide (TCN) concentrations in earth surface materials has been an important development for understanding a host of earth surface processes. Uncertainty in cosmogenic nuclide production rates has hampered application of this method. Here, we contribute to the estimation of 10Be production rates by reporting both preliminary 10Be concentrations and independent radiocarbon dates from a low latitude, high elevation site. Our study site in the southeastern Peruvian Andes (~13.9°S, 70.9°W, 4850 m asl) is centered on a moraine set, known as the Huancané II moraines, that represents a ~4 km expansion of Quelccaya Ice Cap during late glacial time. At this location, organic material situated both stratigraphically below and above moraines in two adjacent valleys provide material for radiocarbon dating. Based on geomorphic arguments, we correlate results from the two valleys. The timing of ice cap margin advance is bracketed by 13 radiocarbon ages on organic material within the outermost Huancané II moraines that range from 13.6 to 12.5 ka. Two stratigraphic sections upvalley from the moraines yield 6 radiocarbon ages from 11.3 to 12.4 ka, indicating the time of retreat . We computed the probability density function that lies between these two sets of dates, and assign an age of 12.4 ka (+/-???) for the formation of the Huancané II moraines. Calculating beryllium-10 exposure dates from the measured concentrations yield exposure dates that significantly underestimate the independently determined age of the moraine (~8-30%), if existing production rate estimates are used. We suggest that the radiocarbon age for the moraines can be used as a robust independent calibration for 10Be production rates at this site.

Age scatter in cosmogenic exposure-age chronologies in the McMurdo Dry Valleys, Antarctica: implications for regional glacial history and sampling strategies

NASA Astrophysics Data System (ADS)

Swanger, K. M.; Schaefer, J. M.; Winckler, G.; Lamp, J. L.; Marchant, D. R.

2016-12-01

Based on surface exposure dating of moraines and drifts, East Antarctic outlet glaciers in the McMurdo Dry Valleys (MDV) advanced during the mid-Pliocene and/or early-Pleistocene. However, scatter in exposure ages is common for these deposits (and other glacial drifts throughout Antarctica), making it difficult to tie glacial advances to specific climate intervals. In order to constrain the sources of scatter, we mapped and dated 15 cold-based drifts in Taylor Valley and the Olympus Range in the MDV. A secondary goal was to build a regional climate record, for comparison with fluctuations of the local outlet glaciers. Our alpine drift record is confined to the late-Pleistocene, with glacial advances during interglacial periods. Based on 54 3He exposure dates on alpine drifts, age scatter is common in the MDV on both recent and ancient deposits. Where it occurs, age scatter is likely caused by inheritance of cosmogenic nuclides previous to glacial entrainment and stacking of multiple cold-based drifts. Nuclide inheritance of >1 Myr is possible, but this is relatively rare and confined to regions where englacial debris is sourced from stable, high-elevation plateaus. On the other hand, drifts associated with glaciers bound by steep cirque headwalls and arêtes exhibit significantly less age scatter. Given the cold-based nature of MDV alpine and outlet glaciers, deposition of multiple stacked drift sheets also contributes to age scatter, with the implication that it might be possible to date multiple advances of cold-based ice. These results serve to inform better sampling strategies on cold-based drifts throughout Antarctica.

Rates of surface lowering and landscape development in southern South Africa: a cosmogenic view

NASA Astrophysics Data System (ADS)

Richardson, Janet; Vanacker, Veerle; Lang, Andreas; Hodgson, David

2016-04-01

The landscape of southern South Africa is characterised by large-scale erosion surfaces, including extensive pediments and multiple strath terraces, which document discordant river evolution through resistant quarzitic lithologies of the Cape Fold Belt (CFB). The timing and rate of erosion is poorly constrained. New cosmogenic ages from surfaces in South Africa are presented using in situ produced 10Be. Strath terraces in deeply incised rivers at two sites within the CFB indicate slow rates of erosion (1.54 - 11.79 m/Ma), which are some of the lowest rates recorded globally. Four pediment surfaces and a depth profile of the thickest pediment were also dated, and the results indicate that there are low rates of surface lowering on the pediments (0.44 - 1.24 m/Ma). The pediments are long-lived features (minimum exposure ages of 0.47 - 1.09 Ma), and are now deeply dissected. Given the minimum exposure ages, calculated river incision rates (42- 203 m/Ma) suggest that after a long period of geomorphic stability during pediment formation there was a discrete phase of increased geomorphic activity. The calculated minimum exposure ages are considered dubious because: 1) known rates of surrounding river incision (published and ours); 2) the climate conditions and time necessary for ferricrete formation on the pediment surfaces and; 3) the deeply incised catchments in the CFB on which the pediments sit, which all point to the pediments being much older. The pediments are fossilised remnants of a much larger geomorphic surface that formed after the main phase of exhumation in southern Africa. They form a store of sediment that currently sit above the surrounding rivers that have some of the lowest erosion rates in the world. These results indicate that steep topography can prevail even in areas of low erosion and tectonic quiescence, and that whilst cosmogenic dating of landscapes is an exciting development in earth sciences, care is needed especially in ancient settings. We strongly suggest benchmarking chronometric information with geomorphic and stratigraphic information.

Buried glacier ice in southern Iceland and its wider significance

NASA Astrophysics Data System (ADS)

Everest, Jeremy; Bradwell, Tom

2003-06-01

Geo-electrical resistivity surveys have been carried out at recently deglaciated sites in front of three glaciers in southern Iceland: Skeiðarájökull, Hrútárjökull, and Virkisjökull. The results show the presence of old glacier ice beneath debris mantles of various thickness. We conclude that buried glacier ice has survived for at least 50 years at Virkisjökull and Hrútárjökull, and probably for over 200 years at Skeiðarájökull. Additional data from a further site have identified a discontinuous ice core within 18th-century jökulhlaup deposits. Photographic and lichenometric evidence show that the overlying debris has been relatively stable, and hence melting of the ice at all four sites is proceeding slowly due to the heat-shielding properties of the overburden. The geomorphic implications are pertinent when considering the potential longevity of buried ice. The possible implications for dating techniques, such as lichenometry, radiocarbon dating and cosmogenic surface-exposure dating are also important, as long-term readjustments of surface forms may lead to dating inaccuracy. Finally, it is recognised that landscape development in areas of stagnant ice topography may post-date initial deglaciation by a considerable degree.

Late Pliocene to Late Quaternary Apparent Exposure Ages from Glacial Deposits in Ak-Shyrak, Central Kyrgyz Tian Shan

NASA Astrophysics Data System (ADS)

Blomdin, R.; Harbor, J.; Stroeven, A. P.; Petrakov, D. A.; Gribenski, N.; Heyman, J.; Ivanov, M.; Caffee, M. W.; Hättestrand, C.; Lifton, N. A.; Rogozhina, I.; Usubaliev, R.

2014-12-01

The Tian Shan in central Asia is one of the world's highest mountain ranges. The 2500 km-long WSW-ENE-trending arc of mountains extends from the western Kyrgyz Republic across northwestern China and almost to the border with Mongolia. Understanding the glacial history of this vast region is important because there is a general lack of paleoclimatic data from this highly continental location, at the confluence of major climate systems, and because glaciers are sensitive monitors of climate change. We examine the glacial history of the Ak-Shyrak massif and surrounding plateaus with average altitudes of ~3500 m a.s.l. To reconstruct the glacial history of this area we use a combined approach including geomorphological mapping, and cosmogenic nuclide surface exposure dating of erratic boulders on glacial landforms. We observe large site-specific scatter in our 10Be and 26Al exposure ages. Apparent minimum surface exposure ages range from ~2 ka to ~2.5 Ma, with early Quaternary- late Pliocene apparent exposure ages relating to some of the highest 10Be concentrations ever recorded for glacial deposits. Most dated boulders, however, fall in the apparent exposure age range of 100 ka to 300 ka. Consistent with previous results from the western and central Tian Shan, none of our boulders record a global last glacial maxima expansion of glaciers, and this contrasts to data from the eastern Kyrgyz Tian Shan. This spatial variation in glacier extent might be due to differences in paleoclimate. However, local physiographic conditions (e.g. altitude, slope, aspect) or external forcing factors other than climate (e.g., landslides) may cause local or regional differences in glacier response. We refrain from assigning mapped glacial advances to marine oxygen isotope stages because of the considerable age scatter. Finally we assess and discuss possible reasons for the observed age scatter and early Quaternary-late Pliocene apparent exposure ages in terms of prior and/or incomplete exposure histories of individual samples and compare our data to other regional datasets.

Cosmogenic 10Be Dating of Early and Latest Holocene Moraines on Nevado Salcantay in the Southern Peruvian Andes

NASA Astrophysics Data System (ADS)

Licciardi, J. M.; Schaefer, J. M.; Lund, D. C.

2007-12-01

A two-fold sequence of nested lateral and end moraines was mapped in a glacial trough emanating from the southwest flank of Nevado Salcantay (6271 m; ~13°S latitude), the highest peak in the Cordillera Vilcabamba of southern Peru. The field area is situated 25 km due south of the archaeological site of Machu Picchu. Outer and inner moraines in the sequence were deposited by valley glaciers that terminated ~5 km and ~3 km, respectively, from their headwall on the Salcantay summit massif. Cosmogenic 10Be surface exposure dating of granitic boulders sampled on the Salcantay moraines is underway and has provided the first numerical ages for these deposits. Initial results indicate ages of 8.1 ± 0.1 10Be ka for the outer moraine and 200 ± 20 10Be years for the sharp-crested inner moraine. These ages are derived using the CRONUS-Earth 10Be exposure age calculator (version 2.0) and expressed with respect to the Lal- Stone production rate scaling scheme using the standard atmosphere. The outer and inner moraine ages correspond to glacial events during the early and latest Holocene, respectively. Further 10Be dating of the mapped moraines and similar deposits observed in adjacent drainages on Nevado Salcantay is anticipated to yield a high-resolution chronology of valley glaciation in this segment of the southern Peruvian Andes. The new results bridge an important gap between existing Andean glacier records to the north and south, and complement available ice core and lacustrine paleoclimate records in the vicinity, thereby expanding spatial and temporal coverage for identifying patterns of Holocene climate change in the tropical Andes. Notably, the inner moraine age correlates with the timing of the Little Ice Age as defined in northern mid- and high latitude glacier records, and suggests considerable expansion of valley glaciers in the southern Peruvian Andes during this climatic minimum. Apart from their paleoclimatic significance, the initial results also demonstrate the utility of 10Be exposure dating for historical surface deposits.

Surface Exposure Dating of Glaciated Landscapes in Washington Land, Northwest Greenland

NASA Astrophysics Data System (ADS)

Reusche, M.; Ceperley, E. G.; Marcott, S. A.; Brook, E.; Mix, A. C.

2016-12-01

The timing and rate of sea-level contribution from the Greenland ice sheet (GIS) and its outlet glaciers through the 21st century is uncertain. Given the long response time of ice sheets, characterizing the sensitivity of the GIS to both atmospheric and oceanic forcings in the past plays a vital role in forecasting future GIS changes. Our terrestrial-based study is primarily focused along the margins of the marine-terminating Petermann Glacier of northwestern Greenland, and is part of a larger multidisciplinary research effort with oceanographers, geophysicists, and atmospheric scientists that aims to better understand Petermann's response to past perturbations in climate and the primary mechanisms that drive those changes. In order to more accurately determine the ice sheet history of the northwestern sector of the GIS, rock samples from erratic boulders on moraines and from across an expansive ice free region (Washington Land) adjacent to Nares Strait were collected for surface exposure dating with 10Be. The project goal is to apply exposure histories from these glacial erratics to determine the timing and rate of GIS retreat since the last glacial maximum from Nares Strait up to the relatively `fresh' moraines that front the present GIS and Petermann Glacier margins nearly 70 km away. Moraine chronologies will also be constructed from these presumably late Holocene moraines, which serve as unique evidence of pre-Little Ice Age (LIA) Neoglaciation that are often obliterated from the landscape due to the large extent of the LIA advance across much of Greenland. Preliminary exposure ages and results will be presented and discussed within the context of the ice-ocean-atmosphere system of northwestern Greenland and compared to ongoing and prior work.

Observations on Mildew Susceptibility of Painted Surfaces in Tropical Chamber Exposure

DTIC Science & Technology

1983-12-01

resins of iron oxide, red iron urea formaldehyde or oxide. blends of urea / melamine + modifiers, stabili- zers, wetting and sus- pension agents. MIL-E...type, modified or chromate yellow, molyb- with not less than 20% date orange, carbazole di- butylated melamine oxazine violet, yellow formaldehyde ...com- Pure short oil length Enamel, Modified Alkyd posed of cobalt, zinc, phthalic alkyd resin Camouflage, Lusterless and chromium oxides, and/ baking

Reconstruction of the Earthquake History of Limestone Fault Scarps in Knidos Fault Zone Using in-situ Chlorine-36 Exposure Dating and "R" Programming Language

NASA Astrophysics Data System (ADS)

Sahin, Sefa; Yildirim, Cengiz; Akif Sarikaya, Mehmet; Tuysuz, Okan; Genc, S. Can; Ersen Aksoy, Murat; Ertekin Doksanalti, Mustafa

2016-04-01

Cosmogenic surface exposure dating is based on the production of rare nuclides in exposed rocks, which interact with cosmic rays. Through modelling of measured 36Cl concentrations, we might obtain information of the history of the earthquake activity. Yet, there are several factors which may impact production of rare nuclides such as geometry of the fault, topography, geographic location of the study area, temporal variations of the Earth's magnetic field, self-cover and denudation rate on the scarp. Recently developed models provides a method to infer timing of earthquakes and slip rates on limited scales by taking into account these parameters. Our study area, the Knidos Fault Zone, is located on the Datça Peninsula in Southwestern Anatolia and contains several normal fault scarps formed within the limestone, which are appropriate to generate cosmogenic chlorine-36 (36Cl) dating models. Since it has a well-preserved scarp, we have focused on the Mezarlık Segment of the fault zone, which has an average length of 300 m and height 12-15 m. 128 continuous samples from top to bottom of the fault scarp were collected to carry out analysis of cosmic 36Cl isotopes concentrations. The main purpose of this study is to analyze factors affecting the production rates and amount of cosmogenic 36Cl nuclides concentration. Concentration of Cl36 isotopes are measured by AMS laboratories. Through the local production rates and concentration of the cosmic isotopes, we can calculate exposure ages of the samples. Recent research elucidated each step of the application of this method by the Matlab programming language (e.g. Schlagenhauf et al., 2010). It is vitally helpful to generate models of Quaternary activity of the normal faults. We, however, wanted to build a user-friendly program through an open source programing language "R" (GNU Project) that might be able to help those without knowledge of complex math programming, making calculations as easy and understandable as possible. Through our codes, physical parameters, statistical analysis and graphics production of the fault models can be generated for each platform. This project is supported by the Scientific and Technological Research Council of Turkey (TUBITAK, Grant number: 113Y436) This study was conducted with the Decision of the Council of Ministers with No. 2013/5387 on the date 30.09.2013 and was done with the permission of Knidos Presidency of excavation in accordance with the scope of Knidos Excavation and Research carried out on behalf of Selcuk University and Ministry of Culture and Tourism. Keywords: Knidos, geomorphology, modelling, cosmogenic surface exposure dating, chlorine36

The Lunar Environment: Determining the Health Effects of Exposure to Moon Dusts

NASA Technical Reports Server (NTRS)

Khan-Mayberry, Noreen

2007-01-01

The moon's surface is covered with a thin layer of fine, charged, reactive dust capable of layer of fine, charged, reactive dust capable of capable of entering habitats and vehicle compartments, where it can result in crewmember health problems. NASA formed the Lunar Airborne Dust Toxicity Advisory Group (LADTAG) to study the effects of exposure to Lunar Dust on human health. To date, no scientifically defensible toxicological studies have been performed on lunar dusts, specifically the determination of exposure limits and their affect on human health. The multi-center LADTAG (Lunar Airborne Dust Toxicology center LADTAG (Lunar Airborne Dust Toxicology Advisory Group) was formed in response to the Office of the Chief Health and Medical Office s (OCHMO) request to develop recommendations for defining risk (OCHMO) request to develop recommendations for defining risk defining risk criteria for human lunar dust exposure.

Evaluation of seals, lubricants, and adhesives used on LDEF

NASA Technical Reports Server (NTRS)

Dursch, Harry; Keough, Bruce; Pippin, Gary

1993-01-01

A wide variety of seals, lubricants, and adhesives were used on the Long Duration Exposure Facility (LDEF). The results, to date, of the Systems Special Investigation Group (SIG) and the Materials SIG investigation into the effect of the long term low Earth orbit (LEO) exposure on these materials is discussed. Results of this investigation show that if the material was shielded from exposure to LDEF's external environment, the 69 month exposure to LEO had minimal effect on the material. However, if the material was on LDEF's exterior surface, a variety of events occurred ranging from no material change, to changes in mechanical or physical properties, to complete disappearance of the material. The results are from the following sources: (1) visual examinations and/or testing of materials performed by various LDEF experimenters, (2) testing done at Boeing in support of the Materials or Systems SIG investigations, (3) testing done at Boeing on Boeing hardware flown on LDEF.

Gender's Role in Exposure to Interparental Violence, Acceptance of Violence, Self-Efficacy, and Physical Teen Dating Violence Among Quebec Adolescents.

PubMed

Ruel, Catherine; Lavoie, Francine; Hébert, Martine; Blais, Martin

2017-05-01

Despite efforts to prevent physical teen dating violence, it remains a major public health issue with multiple negative consequences. This study aims to investigate gender differences in the relationships between exposure to interparental violence (mother-to-father violence, father-to-mother violence), acceptance of dating violence (perpetrated by boys, perpetrated by girls), and self-efficacy to disclose teen dating violence. Data were drawn from Waves 1 and 2 of the Quebec Youth Romantic Relationships Project, conducted with a representative sample of Quebec high school students. Analyses were conducted on a subsample of 2,564 teenagers who had been in a dating relationship in the past 6 months (63.8% girls, mean age of 15.3 years). Path analyses were conducted to investigate the links among exposure to interparental violence, acceptance of violence, self-efficacy to disclose teen dating violence (measured at Wave 1), and physical teen dating violence (measured at Wave 2). General exposure to interparental violence was linked, through acceptance of girl-perpetrated violence, to victimization among both genders and to girls' perpetration of physical teen dating violence. No significant difference was identified in the impact of the gender of the perpetrating parent when considering exposure to interparental violence. Self-efficacy to disclose personal experiences of violence was not linked to exposure to interparental violence or to experiences of physical teen dating violence. The findings support the intergenerational transmission of violence. Moreover, the findings underline the importance of targeting acceptance of violence, especially girl-perpetrated violence, in prevention programs and of intervening with children and adolescents who have witnessed interparental violence.

Glacial-Geomorphological Evidence for Past Ice Cover in the Western Amundsen Sea Embayment of Antarctica

NASA Astrophysics Data System (ADS)

Roberts, S. J.; Johnson, J.; Ireland, L.; Rood, D. H.; Schaefer, J. M.; Whitehouse, P. L.; Pollard, D.

2016-12-01

Reliable model predictions of the future evolution of the West Antarctic Ice Sheet in the Amundsen Sea Embayment of Antarctica are currently hindered by a lack of data on the regional thinning history, particularly to the west of Thwaites Glacier. Our project will fill this critical gap by acquiring glacial-geological data, in particular, a high density of cosmogenic exposure ages that record ice sheet changes in the western Amundsen Sea Embayment over the past 20,000 years. In 2015/6, during the first of two field seasons in the region, we collected glacial-geomorphological evidence and cosmogenic surface exposure dating samples to constrain past ice cover of nunataks around Mt Murphy, which are adjacent to the Pope Glacier. The presence of abundant rounded granite and gneiss cobbles perched on bedrock ridges and terraces up to 885 m asl, as well as extensive striated bedrock above this height, indicate that ice was much thicker in the past. We also present preliminary results from a novel study on Turtle Rock, a key site for understanding past fluctuations of Pope Glacier. We used an unmanned aerial vehicle (UAV) to map the geomorphology of selected areas in greater detail than is currently possible from high-resolution satellite imagery, and ground-truthed the data by measuring the size, orientation and lithological composition of erratic cobbles and boulders. Combined with surface exposure dating, we will use these datasets to determine whether there were multiple phases of ice overriding, and the timing of thinning of Pope Glacier since the Last Glacial Maximum.

Up Close and Personal

NASA Image and Video Library

2014-05-08

This image is one of the highest-resolution MDIS observations to date! Many craters of varying degradation states are visible, as well as gentle terrain undulations. Very short exposure times are needed to make these low-altitude observations while the spacecraft is moving quickly over the surface; thus the images are slightly noisier than typical MDIS images. This image was acquired as a high-resolution targeted observation. Targeted observations are images of a small area on Mercury's surface at resolutions much higher than the 200-meter/pixel morphology base map. It is not possible to cover all of Mercury's surface at this high resolution, but typically several areas of high scientific interest are imaged in this mode each week. Date acquired: March 15, 2014 Image Mission Elapsed Time (MET): 37173522 Image ID: 5936740 Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS) Center Latitude: 71.91° Center Longitude: 232.7° E Resolution: 5 meters/pixel Scale: The image is approximately 8.3 km (5.2 mi.) across. Incidence Angle: 79.4° Emission Angle: 4.0° Phase Angle: 83.4° http://photojournal.jpl.nasa.gov/catalog/PIA18370

Glacial and volcanic evolution on Nevado Coropuna (Tropical Andes) based on cosmogenic 36Cl surface exposure dating

NASA Astrophysics Data System (ADS)

Úbeda, J.; Palacios, D.; Vázquez-Selém, L.

2012-04-01

We have reconstructed the evolution of the paleo-glaciers of the volcanic complex Nevado Coropuna (15°S, 72°W; 6377 m asl) through the interpretation and dating of geomorphological evidences. Surface exposure dating (SED) based on the accumulation of 36Cl on the surface of moraine boulders, polished bedrock and lava flows allowed: 1) to confirm that the presence of ice masses in the region dates back to >80ka; 2) to produce chronologies of glacial and volcanic phases for the last ~21 ka; and 3) to obtain evidences of the reactivation of volcanic activity after the Last Glacial Maximum. Bromley et al. (2009) presented 3He SED ages of 21 ka for moraine boulders on the Mapa Mayo valley, to the North of Nevado Coropuna. Our 36Cl SED SED for moraine boulders from the valleys on the NE sector of the volcanic complex suggest a maximum initial advance between 20 and 16 ka, followed by another expansion of similar extent at 12-11 ka. On the Southern slope of Nevado Coropuna, the 36Cl ages show a maximum initial advance that reaches to the level of the Altiplano at 14 ka, and a re-advance at ~10-9 ka BP. Other data show minor re-advances at 9 ka on the Northern slope and at 6 ka to the South of the volcanic complex. These minor positive pulses interrupted a fast deglaciation process during the Holocene as shown by two series of 36Cl SED from polished rock surfaces on successively higher altitudes along the valleys of rivers Blanco and Cospanja, to the SW and SE. Despite the global warming occuring since 20 ka, deduced from the record of sea surface paleo-temperature of the Galapago Islands (Lea et al, 2006), the evolution of the fresh-water plankton from Lake Titicaca (Fritz et al, 2007) is consistent with sustained glacial conditions until 10-9 ka as suggested by the present work. Exposure ages of three lava flows indicate a reactivation of the magmatic system as the paleo-glaciers abandonned the slopes. The eruptive activity migrated from the West, where we found a lava flow of 6 ka, to the East, where we dated two units similar to the previous one at 2 and <1ka. Bromley, G.R. et al., 2009. Relative timing of last glacial maximum and late-glacial events in the central tropical Andes. Quaternary Science Reviews, 1-13. Bromley, R.M. et al., 2011. Glacier fluctuations in the southern Peruvian Andes during the late-glacial period, constrained with cosmogenic 3He. Journal of Quaternary Science, 26 (1): 37-43. Fritz, S.C. et al., 2007. Lake Titicaca 370KYr LT01-2B Sediment Database. Lake Titicaca 370KYr LT01-2B Sediment Data. IGBP PAGES/World Data Center-A for Paleoclimatology Data Contribution Series # 92-008. NOAA/NGDC Paleoclimatology Program. Boulder (EEUU). Lea, D.W. et al., 2006. Galápagos TR163-22 Foraminiferal ^18O and Mg/Ca Data and SST Reconstruction. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2006-090. NOAA/NCDC Paleoclimatology Program, Boulder (EEUU). Research funded by CGL2009-7343 project, Government of Spain.

The relationship between violence in the family of origin and dating violence among college students.

PubMed

Gover, Angela R; Kaukinen, Catherine; Fox, Kathleen A

2008-12-01

Prior research has established that violence in dating relationships is a serious social problem among adolescents and young adults. Exposure to violence during childhood has been linked to dating violence victimization and perpetration. Also known as the intergenerational transmission of violence, the link between violence during childhood and dating violence has traditionally focused on physical violence. This research examines the relationship between experiencing and perpetrating dating violence and exposure to violence in the family of origin. Specifically, the current research examines gender differences in the relationship between exposure to violence during childhood and physical and psychological abuse perpetration and victimization. Data were collected from a sample of approximately 2,500 college students at two southeastern universities. Findings indicate that childhood exposure to violence is a consistent predictor of involvement in relationships characterized by violence for males and females. The implications of the current research on policy are discussed.

10Be surface exposure dating reveals strong active deformation in the central Andean backarc interior

NASA Astrophysics Data System (ADS)

García Morabito, Ezequiel; Terrizzano, Carla; Zech, Roland; Willett, Sean; Yamin, Marcela; Haghipour, Negar; Wuethrich, Lorenz; Christl, Marcus; María Cortes, José; Ramos, Victor

2016-04-01

Understanding the deformation associated with active thrust wedges is essential to evaluate seismic hazard. How is active faulting distributed throughout the wedge, and how much deformation is taken up by individual structures? We address these questions for our study region, the central Andean backarc of Argentina. We combined a structural and geomorphological approach with surface exposure dating (10Be) of alluvial fans and strath terraces in two key localities at ~32° S: the Cerro Salinas, located in the active orogenic front of the Precordillera, and the Barreal block in the interior of the Andean mountain range. We analysed 22 surface samples and 6 depth profiles. At the thrust front, the oldest terrace (T1) yields an age of 100-130 ka, the intermediate terrace (T2) between 40-95 ka, and the youngest terrace (T3) an age of ~20 ka. In the Andean interior, T1´ dates to 117-146 ka, T2´ to ~70 ka, and T3´ to ~20 ka, all calculations assuming negligible erosion and using the scaling scheme for spallation based on Lal 1991, Stone 2000. Vertical slip rates of fault offsets are 0.3-0.5 mm/yr and of 0.6-1.2 mm/yr at the thrust front and in the Andean interior, respectively. Our results highlight: i) fault activity related to the growth of the Andean orogenic wedge is not only limited to a narrow thrust front zone. Internal structures have been active during the last 150 ka, ii) deformation rates in the Andean interior are comparable or even higher that those estimated and reported along the emerging thrust front, iii) distribution of active faulting seems to account for unsteady state conditions, and iv) seismic hazards may be more relevant in the internal parts of the Andean orogen than assumed so far. References Lal, D., 1991: Cosmic ray labeling of erosion surfaces: In situ nuclide production rates and erosion models. Earth and Planetary Science Letters 104: 424-439. Stone, J.O., 2000: Air pressure and cosmogenic isotope production. Journal of Geophysical Research 105 (B10): 23753-23759

Quaternary Slip History for the Agua Blanca Fault, northern Baja California, Mexico

NASA Astrophysics Data System (ADS)

Gold, P. O.; Behr, W. M.; Rockwell, T. K.; Fletcher, J. M.

2017-12-01

The Agua Blanca Fault (ABF) is the primary structure accommodating San Andreas-related right-lateral slip across the Peninsular Ranges of northern Baja California. Activity on this fault influences offshore faults that parallel the Pacific coast from Ensenada to Los Angeles and is a potential threat to communities in northern Mexico and southern California. We present a detailed Quaternary slip history for the ABF, including new quantitative constraints on geologic slip rates, slip-per-event, the timing of most recent earthquake, and the earthquake recurrence interval. Cosmogenic 10Be exposure dating of clasts from offset fluvial geomorphic surfaces at 2 sites located along the western, and most active, section of the ABF yield preliminary slip rate estimates of 2-4 mm/yr and 3 mm/yr since 20 ka and 2 ka, respectively. Fault zone geomorphology preserved at the younger site provides evidence for right-lateral surface displacements measuring 2.5 m in the past two ruptures. Luminescence dating of an offset alluvial fan at a third site is in progress, but is expected to yield a slip rate relevant to the past 10 kyr. Adjacent to this third site, we excavated 2 paleoseismic trenches across a sag pond formed by a right step in the fault. Preliminary radiocarbon dates indicate that the 4 surface ruptures identified in the trenches occurred in the past 6 kyr, although additional dating should clarify earthquake timing and the mid-Holocene to present earthquake recurrence interval, as well as the likely date of the most recent earthquake. Our new slip rate estimates are somewhat lower than, but comparable within error to, previous geologic estimates based on soil morphology and geodetic estimates from GPS, but the new record of surface ruptures exposed in the trenches is the most complete and comprehensively dated earthquake history yet determined for this fault. Together with new and existing mapping of tectonically generated geomorphology along the ABF, our constraints show that contrary to some theories of fault interaction and activity for this section of the San Andreas system, the Agua Blanca Fault has been active over the late Holocene, and should be considered as a potential source of seismic hazard.

Potential improvement of Schmidt-hammer exposure-age dating (SHD) of moraines in the Southern Alps, New Zealand, by application of the new electronic Schmidt-hammer (SilverSchmidt)

NASA Astrophysics Data System (ADS)

Winkler, Stefan; Corbett, David

2014-05-01

The Southern Alps of New Zealand are among the few key study sites for investigating Holocene glacier chronologies in the mid-latitudinal Southern Hemisphere. Their characteristic highly dynamic geomorphological process systems prove, however, to be a considerable challenge for all attempts to date and palaeoclimatologically interpret the existing Holocene moraines record. As a multi-proxy approach combining 10Be terrestrial cosmogenic nuclide dating (TCND) with Schmidt-hammer testing, the recently developed Schmidt-hammer exposure-age dating (SHD) has already shown its potential in this study area (cf. Winkler 2005, 2009, 2013). An electronic Schmidt-hammer (named SilverSchmidt) was introduced by the manufacturer of the original mechanical Schmidt-hammer (Proceq SA) a few years ago. It offers, in particular, facilities for much easier data processing and constitutes a major improvement and potential replacement for the mechanical Schmidt-hammer. However, its different approach to the measurement of surface hardness - based on Q-(velocity) values instead of R-(rebound) values - is a potential drawback. This difference effectively means that measurements from the two instruments are not easily interconvertible and, hence, that the instruments cannot be used interchangeably without previous comparative tests of both instruments under field conditions. Both instruments used in this comparative study were N-type models with identical impact energy of 2.207 Nm for the plunger. To compare both instruments and explore interconvertibility, parallel measurements were performed on a selected number of boulders (10 boulders per site with 5 impacts each, at least 2 sites per moraine) on moraines of homogeneous lithology but different established ages covering the entire Holocene and the Late Glacial. All moraines are located east of the Main Divide of the Southern Alps at Mueller Glacier, Tasman Glacier, and in the outer Tasman River Valley. All paired samples (n = 50) were collected so that the plunger impacts of both instruments were set close together on the rock surface (to avoid any influence of modifications to the surface by consecutive impacts on the same spot). In order to test their performance at the higher and lower end of surface hardness, similar paired sample tests were also made on the full-metal test anvil. The results of paired samples for all sites/moraines reveal that Q-/R-value pairs are closely clustered for young surfaces but more scattered for the older ones with a corresponding moderate R2 for a calculated linear trend. The greater variability of the older, weathered surfaces with greater scatter and hence higher standard deviations and broader confidence intervals has been recognised in numerous previous Schmidt-hammer studies and is elated to the effects of micro-scale lithological variability, which becomes a more pronounced influence with time exposed to subaerial weathering. But most important, Q-values and R-values are closely related and Q-values are systematically higher than R-values by c. 10 - 12 units over most of the operational range of both instruments. Linear conversion equations indicate a conversion factor in the order of + 11 units is applicable when converting R-values to Q-values. These estimates agree well with data obtained on the standard test anvil. Given the apparent interconvertibility of the two instruments, the SilverSchmidt is regarded as a potential replacement for the mechanical Schmidt hammer. This enables, moreover, continuity in study areas with existing R-value data archives. However, when comparing data sets of different age, adjustments must be made for any changes to the instrumental calibration value over time. References: Winkler, S. (2005): The 'Schmidt hammer' as a relative-age dating technique: potential and limitations of its application on Holocene moraines in Mt Cook National Park, Southern Alps, New Zealand. New Zealand Journal of Geology and Geophysics 48, 105 - 116. Winkler, S. (2009): First attempt to combine terrestrial cosmogenic nuclide (10Be) and Schmidt hammer relative-age dating: Strauchon Glacier, Southern Alps, New Zealand. Central European Journal of Geosciences 1, 274 - 290. Winkler, S. (2013): Investigation of late-Holocene moraines in the western Southern Alps, New Zealand, applying Schmidt-hammer exposure-age dating (SHD). The Holocene (online), doi: 10.1177/0959683613512169.

Polymer matrix composites on LDEF experiments M0003-9 and M0003-10

NASA Technical Reports Server (NTRS)

Steckel, Gary L.; Cookson, Thomas; Blair, Christopher

1992-01-01

Over 250 polymer matrix composites were exposed to the natural space environment on Long Duration Exposure Facility (LDEF) experiments M0003-9 and 10. The experiments included a wide variety of epoxy, thermoplastic, polyimide, and bismalimide matrix composites reinforced with graphite, glass, or organic fibers. A review of the significant observations and test results obtained to date is presented. Estimated recession depths from atomic oxygen exposure are reported and the resulting surface morphologies are discussed. The effects of the LDEF exposure on the flexural strength and modulus, short beam shear strength, and coefficient of thermal expansion of several classes of bare and coated composites are reviewed. Lap shear data are presented for composite-to-composite and composite-to-aluminum alloy samples that were prepared using different bonding techniques and subsequently flown on LDEF.

Characterising Late-Holocene glacier variability in the southern tropical Andes

NASA Astrophysics Data System (ADS)

Bromley, G.; Winckler, G.; Hall, B. L.; Schaefer, J. M.

2011-12-01

Accurate resolution of both the timing and magnitude of Late-Holocene climate events, such as the Little Ice Age, is vital in order to test different hypotheses for the causes and propagation of such climate variability. However, in contrast to higher latitudes, well-dated records from the tropics are relatively rare and the overall climatic structure of the last millennium remains unresolved. Much of this uncertainty stems from difficulties associated with radiocarbon dating in these dry, often high-altitude environments, a situation that now is being addressed through the application and refinement of cosmogenic surface-exposure methods. We present detailed Late-Holocene moraine records, resolved with radiocarbon and surface-exposure dating, from sites across the Andes of southern Peru. Specifically, we describe glacial records from both the arid Western Cordillera, where glaciation is limited by moisture availability, and the humid Eastern Cordillera, where ablation is controlled primarily by air temperature. In both locations, the most recent advance is marked by two to three unweathered terminal moraines located several hundred metres beyond the modern ice margins. Our chronology indicates that, while the advance occurred broadly in step with the classic 'Little Ice Age', the maximum glacial extent in southern Peru was achieved relatively early on and that the 18th and 19th centuries were dominated by glacier retreat. In a broader temporal context, our data also confirm that, in contrast to northern temperate latitudes, the event in southern Peru was the most recent significant interruption in a progressive Holocene retreat. The consistency in glacier response between the different climate zones suggests (i) that this pattern of Late-Holocene climate variability was of at least regional extent and (ii) that temperature fluctuations were the primary driving mechanism.

Chronology of the last glacial maximum in the upper Bear River Basin, Utah

USGS Publications Warehouse

Laabs, B.J.C.; Munroe, Jeffrey S.; Rosenbaum, J.G.; Refsnider, K.A.; Mickelson, D.M.; Singer, B.S.; Caffee, M.W.

2007-01-01

The headwaters of the Bear River drainage were occupied during the Last Glacial Maximum (LGM) by outlet glaciers of the Western Uinta Ice Field, an extensive ice mass (???685 km2) that covered the western slope of the Uinta Mountains. A well-preserved sequence of latero-frontal moraines in the drainage indicates that outlet glaciers advanced beyond the mountain front and coalesced on the piedmont. Glacial deposits in the Bear River drainage provide a unique setting where both 10Be cosmogenic surface-exposure dating of moraine boulders and 14C dating of sediment in Bear Lake downstream of the glaciated area set age limits on the timing of glaciation. Limiting 14C ages of glacial flour in Bear Lake (corrected to calendar years using CALIB 5.0) indicate that ice advance began at 32 ka and culminated at about 24 ka. Based on a Bayesian statistical analysis of cosmogenic surface-exposure ages from two areas on the terminal moraine complex, the Bear River glacier began its final retreat at about 18.7 to 18.1 ka, approximately coincident with the start of deglaciation elsewhere in the central Rocky Mountains and many other alpine glacial localities worldwide. Unlike valleys of the southwestern Uinta Mountains, deglaciation of the Bear River drainage began prior to the hydrologie fall of Lake Bonneville from the Provo shoreline at about 16 ka. ?? 2007 Regents of the University of Colorado.

Investigating Rare Risk Factors for Nipah Virus in Bangladesh: 2001-2012.

PubMed

Hegde, Sonia T; Sazzad, Hossain M S; Hossain, M Jahangir; Alam, Mahbub-Ul; Kenah, Eben; Daszak, Peter; Rollin, Pierre; Rahman, Mahmudur; Luby, Stephen P; Gurley, Emily S

2016-12-01

Human Nipah encephalitis outbreaks have been identified almost yearly in Bangladesh since 2001. Though raw date palm sap consumption and person-to-person contact are recognized as major transmission pathways, alternative pathways of transmission are plausible and may not have been identified due to limited statistical power in each outbreak. We conducted a risk factor analysis using all 157 cases and 632 controls surveyed in previous investigations during 2004-2012 to identify exposures independently associated with Nipah, since date palm sap was first asked about as an exposure in 2004. To further explore possible rare exposures, we also conducted in-depth interviews with all cases, or proxies, since 2001 that reported no exposure to date palm sap or contact with another case. Cases were 4.9 (95% 3.2-7.7) times more likely to consume raw date palm sap and 7.3 (95% 4.0-13.4) times more likely to have contact with a Nipah case than controls. In-depth interviews revealed that 39/182 (21%) of Nipah cases reporting neither date palm sap consumption nor contact with another case were misclassified. Prevention efforts should be focused on interventions to interrupt transmission through date palm sap consumption and person-to-person contact. Furthermore, pooling outbreak investigation data is a good method for assessing rare exposures.

The Effects of Temperature, Humidity and Aircraft Fluid Exposure on T800H/3900-2 Composites Bonded with AF-555M Adhesive

NASA Technical Reports Server (NTRS)

Miner, Gilda A.; Hou, Tan-Hung; Lowther, Sharon E.; Thibeault, Sheila A.; Connell, John W.; Blasini, Sheila Roman

2010-01-01

Fiber reinforced resin matrix composites and structural adhesives have found increased usage on commercial and military aircraft in recent years. Due to the lack of service history of these relatively new material systems, their long-term aging performance has not been well established. In this study, single lap shear specimens (SLS) were fabricated by secondary bonding of Scotch-Weld(TradeMark) AF-555M between pre-cured adherends comprised of T800H/3900-2 uni-directional laminates. The adherends were co-cured with wet peel-ply for surface preparation. Each bond-line of the SLS specimen was measured to determine thickness and inspected visually using an optical microscope for voids. A three-year environmental aging plan for the SLS specimens at 82 C (180 F) and 85% relative humidity was initiated. SLS strengths were measured for both controls and aged specimens at room temperature and 82 C. The effect of this exposure on lap shear strength and failure modes to date is reported. In addition, the effects of water, saline water, deicing fluid, JP-5 jet fuel and hydraulic fluid on both the composite material and the adhesive bonds were investigated. The up to date results on the effects of these exposures will be discussed.

A field and glacier modelling based approach to determine the timing and extent of glaciation in southern Africa

NASA Astrophysics Data System (ADS)

Mills, Stephanie C.; Rowan, Ann V.; Barrow, Timothy T.; Plummer, Mitchell A.; Smith, Michael; Grab, Stefan W.; Carr, Simon J.; Fifield, L. Keith

2014-05-01

Moraines identified at high-altitude sites in southern Africa and dated to the last glacial maximum (LGM) indicate that the climate in this region was cold enough to support glaciers. Small glaciers are very sensitive to changes in temperature and precipitation and the identification of LGM moraines in southern Africa has important palaeoclimatic implications concerning the magnitude of temperature change and the seasonality of precipitation during the last glacial cycle. This paper presents a refined time-frame for likely glaciations based on surface exposure dating using Cl-36 at sites in Lesotho and reports results of a 2D glacier energy balance and ice flow modelling approach (Plummer and Phillips, 2003) to evaluate the most likely climatic scenarios associated with mapped moraine limits. Samples for surface exposure dating were collected from glacially eroded bedrock at several locations and yield ages within the timescale of the LGM. Scatter in the ages may be due to insufficient erosion of the bedrock surface due to the small and relatively thin nature of the glaciers. To determine the most likely climatic conditions that may have caused the glaciers to reach their mapped extent, we use a glacier-climate model, driven by data from local weather stations and a 30m (ASTER) DEM (sub-sampled to 10m) representation of the topographic surface. The model is forced using modern climate data for primary climatic controls (temperature and precipitation) and for secondary climatic parameters (relative humidity, cloudiness, wind speed). Various sensitivity tests were run by dropping temperature by small increments and by varying the amount of precipitation and its seasonality relative to present-day values. Results suggest that glaciers could have existed in the Lesotho highlands with a temperature depression of ~5-6 ºC and that the glaciers were highly sensitive to small changes in temperature. The additional accumulation of mass through wind redistribution appears to have been important at all but a few sites, suggesting that this must be taken into account when trying to determine a regional climate signal from small glaciers. Our dating and glacier-climate model simulations reinforce the idea that small glaciers existed in the Lesotho Highlands during the LGM, under climatic scenarios that are consistent with other proxy records. Plummer, M.A. and Phillips, F.M. (2003) 2-D numerical model of snow/ice energy balance and ice flow for paleoclimatic interpretation of glacial geomorphic features. Quaternary Science Reviews, 22, 1389-1406.

An optical age chronology of late Quaternary extreme fluvial events recorded in Ugandan dambo soils

USGS Publications Warehouse

Mahan, S.A.; Brown, D.J.

2007-01-01

There is little geochonological data on sedimentation in dambos (seasonally saturated, channel-less valley floors) found throughout Central and Southern Africa. Radiocarbon dating is problematic for dambos due to (i) oxidation of organic materials during dry seasons; and (ii) the potential for contemporary biological contamination of near-surface sediments. However, for luminescence dating the equatorial site and semi-arid climate facilitate grain bleaching, while the gentle terrain ensures shallow water columns, low turbidity, and relatively long surface exposures for transported grains prior to deposition and burial. For this study, we focused on dating sandy strata (indicative of high-energy fluvial events) at various positions and depths within a second-order dambo in central Uganda. Blue-light quartz optically stimulated luminescences (OSL) ages were compared with infrared stimulated luminescence (IRSL) and thermoluminescence (TL) ages from finer grains in the same sample. A total of 8 samples were dated, with 6 intervals obtained at ???35, 33, 16, 10.4, 8.4, and 5.9 ka. In general, luminescence ages were stratigraphically, geomorphically and ordinally consistent and most blue-light OSL ages could be correlated with well-dated climatic events registered either in Greenland ice cores or Lake Victoria sediments. Based upon OSL age correlations, we theorize that extreme fluvial dambo events occur primarily during relatively wet periods, often preceding humid-to-arid transitions. The optical ages reported in this study provide the first detailed chronology of dambo sedimentation, and we anticipate that further dambo work could provide a wealth of information on the paleohydrology of Central and Southern Africa. ?? 2006 Elsevier Ltd. All rights reserved.

Investigating Rare Risk Factors for Nipah Virus in Bangladesh: 2001–2012

PubMed Central

Hegde, Sonia T.; Sazzad, Hossain M. S.; Hossain, M. Jahangir; Alam, Mahbub-Ul; Kenah, Eben; Daszak, Peter; Rollin, Pierre; Rahman, Mahmudur; Luby, Stephen P.; Gurley, Emily S.

2016-01-01

Human Nipah encephalitis outbreaks have been identified almost yearly in Bangladesh since 2001. Though raw date palm sap consumption and person-to-person contact are recognized as major transmission pathways, alternative pathways of transmission are plausible and may not have been identified due to limited statistical power in each outbreak. We conducted a risk factor analysis using all 157 cases and 632 controls surveyed in previous investigations during 2004–2012 to identify exposures independently associated with Nipah, since date palm sap was first asked about as an exposure in 2004. To further explore possible rare exposures, we also conducted in-depth interviews with all cases, or proxies, since 2001 that reported no exposure to date palm sap or contact with another case. Cases were 4.9 (95% 3.2–7.7) times more likely to consume raw date palm sap and 7.3 (95% 4.0–13.4) times more likely to have contact with a Nipah case than controls. In-depth interviews revealed that 39/182 (21%) of Nipah cases reporting neither date palm sap consumption nor contact with another case were misclassified. Prevention efforts should be focused on interventions to interrupt transmission through date palm sap consumption and person-to-person contact. Furthermore, pooling outbreak investigation data is a good method for assessing rare exposures. PMID:27738775

Climate-driven sediment aggradation and incision since the late Pleistocene in the NW Himalaya, India

NASA Astrophysics Data System (ADS)

Dey, Saptarshi; Thiede, Rasmus C.; Schildgen, Taylor F.; Wittmann, Hella; Bookhagen, Bodo; Scherler, Dirk; Jain, Vikrant; Strecker, Manfred R.

2016-09-01

Deciphering the response of sediment routing systems to climatic forcing is fundamental for understanding the impacts of climate change on landscape evolution. In the Kangra Basin (northwest Sub-Himalaya, India), upper Pleistocene to Holocene alluvial fills and fluvial terraces record periodic fluctuations of sediment supply and transport capacity on timescales of 103 to 105 yr. To evaluate the potential influence of climate change on these fluctuations, we compare the timing of aggradation and incision phases recorded within remnant alluvial fans and terraces with climate archives. New surface-exposure dating of six terrace levels with in-situ cosmogenic 10Be indicates the onset of incision phases. Two terrace surfaces from the highest level (T1) sculpted into the oldest preserved alluvial fan (AF1) date back to 53.4 ± 3.2 ka and 43.0 ± 2.7 ka (1σ). T2 surfaces sculpted into the remnants of AF1 have exposure ages of 18.6 ± 1.2 ka and 15.3 ± 0.9 ka, while terraces sculpted into the upper Pleistocene-Holocene fan (AF2) provide ages of 9.3 ± 0.4 ka (T3), 7.1 ± 0.4 ka (T4), 5.2 ± 0.4 ka (T5) and 3.6 ± 0.2 ka (T6). Together with previously published OSL ages yielding the timing of aggradation, we find a correlation between variations in sediment transport with oxygen-isotope records from regions affected by the Indian Summer Monsoon. During periods of increased monsoon intensity and post-Last Glacial Maximum glacial retreat, aggradation occurred in the Kangra Basin, likely due to high sediment flux, whereas periods of weakened monsoon intensity or lower sediment supply coincide with incision.

Visual exposure to obesity: Experimental effects on attraction toward overweight men and mate choice in females.

PubMed

Robinson, E; Christiansen, P

2015-09-01

Cultural differences in ideal body weight are well established, but less research has examined attraction toward potential mates of heavier body weights. We examined whether exposure to obesity increases physical attraction toward overweight men. In Studies 1 and 2, we examined the effect that exposure to obese vs healthy weight men had on female attraction toward an overweight man. Study 3 examined whether females who are regularly exposed to males of heavier body weights reported a greater attraction toward overweight men. Study 4 tested whether females in an online dating study were more likely to choose to date an overweight man, after having been exposed to obesity. Exposure to obesity altered visual perceptions of what normal and therefore healthy body weights were and this resulted in greater attraction toward an overweight man (Studies 1 and 2). Females regularly exposed to men of heavier body weight reported a greater attraction toward overweight men (Study 3). After exposure to obesity, females in an online dating study were more likely to choose to date an overweight man ahead of a healthy weight man (Study 4). Exposure to male obesity increases female attraction toward overweight men and may affect mate choice.

Erosion patterns produced by the paleo Haizishan ice cap, SE Tibetan Plateau

NASA Astrophysics Data System (ADS)

Fu, P.; Stroeven, A. P.; Harbor, J.; Hättestrand, C.; Heyman, J.; Caffee, M. W.

2017-12-01

Erosion is a primary driver of landscape evolution, topographic relief production, geochemical cycles, and climate change. Combining in situ 10Be and 26Al exposure age dating, geomorphological mapping, and field investigations, we examine glacial erosion patterns of the almost 4,000 km2 paleo Haizishan ice cap on the southeastern Tibetan Plateau. Our results show that ice caps on the low relief Haizishan Plateau produced a zonal pattern of landscape modification. In locations where apparent exposure ages on bedrock are consistent with the last deglaciation, complete resetting of the cosmogenic exposure age clock indicates glacial erosion of at least a few meters. However, older apparent exposure ages on bedrock in areas known to have been covered by the paleo ice cap during the Last Glacial Maximum indicate inheritance and thus limited glacial erosion. Inferred surface exposure ages from cosmogenic depth profiles through two saprolites vary from resetting and thus saprolite profile truncation to nuclide inheritance indicating limited erosion. Finally, significant nuclide inheritance in river sand samples from basins on the scoured plateau surface also indicate limited glacial erosion during the last glaciation. Hence, for the first time, our study shows clear evidence of preservation under non-erosive ice on the Tibetan Plateau. As patterns of glacial erosion intensity are largely driven by the basal thermal regime, our results confirm earlier inferences from geomorphology for a concentric basal thermal pattern for the paleo Haizishan ice cap during the LGM.

Lunar Science Conference, 8th, Houston, Tex., March 14-18, 1977, Proceedings. Volume 1 - The moon and the inner solar system. Volume 2 - Petrogenetic studies of mare and highland rocks. Volume 3 - Planetary and lunar surfaces

NASA Technical Reports Server (NTRS)

Merril, R. B.

1977-01-01

Solar system processes are considered along with the origin and evolution of the moon, planetary geophysics, lunar basins and crustal layering, lunar magnetism, the lunar surface as a planetary probe, remote observations of lunar and planetary surfaces, earth-based measurements, integrated studies, physical properties of lunar materials, and asteroids, meteorites, and the early solar system. Attention is also given to studies of mare basalts, the kinetics of basalt crystallization, topical studies of mare basalts, highland rocks, experimental studies of highland rocks, geochemical studies of highland rocks, studies of materials of KREEP composition, a consortium study of lunar breccia 73215, topical studies on highland rocks, Venus, and regional studies of the moon. Studies of surface processes, are reported, taking into account cratering mechanics and fresh crater morphology, crater statistics and surface dating, effects of exposure and gardening, and the chemistry of surfaces.

Organofunctional Silane Modification of Aluminum-Doped Zinc Oxide Surfaces as a Route to Stabilization

DOE PAGES

Matthews, Rachael; Glasser, Emily; Sprawls, Samuel C.; ...

2017-05-01

Aluminum-doped zinc oxide (AZO) is a low-temperature processed transparent conductive oxide (TCO) made of earth abundant elements; its applications are currently limited by instability to heat, moisture, and acidic conditions. We demonstrate that the application of an organofunctional silane modifier mitigates AZO degradation, and explore the interplay between performance and material composition and morphology. Specifically, we evaluate degradation of bare AZO and APTES (3-aminopropyltriethoxysilane)-modified AZO in response to damp heat (DH, 85 °C, 85 % relative humidity) exposure over 1000 h, then demonstrate how surface modification impacts changes in electrical and optical properties, and chemical composition in one of themore » most thorough studies to date. Hall measurements show that the resistivity of AZO increases due to a decrease in electron mobility, with no commensurate change in carrier concentration. APTES decelerates this electrical degradation, without affecting AZO optical properties. Percent transmission and yellowness index of an ensemble of bare and modified AZO are stable upon DH exposure, but haze increases slightly for a discrete sample of modified AZO. Atomic force microscopy (AFM) and optical profilometer (OP) measurements do not show evidence of pitting or delamination after 1000 h DH exposure, but indicate a slight increase in surface roughness on both the nanometer and micron length scales. X-ray photoelectron spectroscopy data (XPS) reveal that the surface composition of bare and silanized AZO is stable over this time frame; oxygen vacancies, as measured by XPS, are also stable with DH exposure, which, together with transmission and Hall measurements, indicate stable carrier concentrations. However, after 1500 h of DH exposure, only bare AZO shows signs of catastrophic destruction. Comparison of the data presented herein to previous reports indicates that the initial AZO composition and microstructure dictate the degradation profile. Furthermore, this work demonstrates that surface modification slows the bulk degradation of AZO, and provides insight into how the material can be more widely used as a transparent electrode in the next generation of optoelectronic devices.« less

Organofunctional Silane Modification of Aluminum-Doped Zinc Oxide Surfaces as a Route to Stabilization

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

Matthews, Rachael; Glasser, Emily; Sprawls, Samuel C.

Aluminum-doped zinc oxide (AZO) is a low-temperature processed transparent conductive oxide (TCO) made of earth abundant elements; its applications are currently limited by instability to heat, moisture, and acidic conditions. We demonstrate that the application of an organofunctional silane modifier mitigates AZO degradation, and explore the interplay between performance and material composition and morphology. Specifically, we evaluate degradation of bare AZO and APTES (3-aminopropyltriethoxysilane)-modified AZO in response to damp heat (DH, 85 °C, 85 % relative humidity) exposure over 1000 h, then demonstrate how surface modification impacts changes in electrical and optical properties, and chemical composition in one of themore » most thorough studies to date. Hall measurements show that the resistivity of AZO increases due to a decrease in electron mobility, with no commensurate change in carrier concentration. APTES decelerates this electrical degradation, without affecting AZO optical properties. Percent transmission and yellowness index of an ensemble of bare and modified AZO are stable upon DH exposure, but haze increases slightly for a discrete sample of modified AZO. Atomic force microscopy (AFM) and optical profilometer (OP) measurements do not show evidence of pitting or delamination after 1000 h DH exposure, but indicate a slight increase in surface roughness on both the nanometer and micron length scales. X-ray photoelectron spectroscopy data (XPS) reveal that the surface composition of bare and silanized AZO is stable over this time frame; oxygen vacancies, as measured by XPS, are also stable with DH exposure, which, together with transmission and Hall measurements, indicate stable carrier concentrations. However, after 1500 h of DH exposure, only bare AZO shows signs of catastrophic destruction. Comparison of the data presented herein to previous reports indicates that the initial AZO composition and microstructure dictate the degradation profile. Furthermore, this work demonstrates that surface modification slows the bulk degradation of AZO, and provides insight into how the material can be more widely used as a transparent electrode in the next generation of optoelectronic devices.« less

Importance of Gender and Attitudes about Violence in the Relationship between Exposure to Interparental Violence and the Perpetration of Teen Dating Violence

ERIC Educational Resources Information Center

Temple, Jeff R.; Shorey, Ryan C.; Tortolero, Susan R.; Wolfe, David A.; Stuart, Gregory L.

2013-01-01

Objective: Mounting evidence has demonstrated a link between exposure to family of origin violence and the perpetration of teen dating violence (TDV). However, only recently have mechanisms underlying this relationship been investigated and very few studies have differentiated between exposure to father-to-mother and mother-to-father violence.…

Exposure of Polymer Film Thermal Control Materials on the Materials International Space Station Experiment (MISSE)

NASA Technical Reports Server (NTRS)

Dever, Joyce; Miller, Sharon; Messer, Russell; Sechkar, Edward; Tollis, Greg

2002-01-01

Seventy-nine samples of polymer film thermal control (PFTC) materials have been provided by the National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) for exposure to the low Earth orbit environment on the exterior of the International Space Station (ISS) as part of the Materials International Space Station Experiment (MISSE). MISSE is a materials flight experiment sponsored by the Air Force Research Lab/Materials Lab and NASA. This paper will describe background, objectives, and configurations for the GRC PFTC samples for MISSE. These samples include polyimides, fluorinated polyimides, and Teflon fluorinated ethylene propylene (FEP) with and without second-surface metallizing layers and/or surface coatings. Also included are polyphenylene benzobisoxazole (PBO) and a polyarylene ether benzimidazole (TOR-LM). On August 16, 2001, astronauts installed passive experiment carriers (PECs) on the exterior of the ISS in which were located twenty-eight of the GRC PFTC samples for 1-year space exposure. MISSE PECs for 3-year exposure, which will contain fifty-one GRC PFTC samples, will be installed on the ISS at a later date. Once returned from the ISS, MISSE GRC PFTC samples will be examined for changes in optical and mechanical properties and atomic oxygen (AO) erosion. Additional sapphire witness samples located on the AO exposed trays will be examined for deposition of contaminants.

Geochronology of Tropical Alpine Glaciations From the Cordillera Huayhuash, Peru

NASA Astrophysics Data System (ADS)

Hall, S. R.; Farber, D. L.; Rodbell, D. T.; Finkel, R. C.; Ramage, J. M.; Smith, J. A.; Mark, B. G.; Seltzer, G. O.

2004-12-01

The Cordillera Huayhuash of the Central Peruvian Andes (10.3° S, 76.9° W) is an ideal range to study regional climate signals and variations in paleo-ice volumes. Located between the Cordillera Blanca to the north and the Junin region to the south, the range trends nearly north-south with modern glaciers confined to the high peaks (>4800 m). Cross-cutting relationships, geomorphology, and correlation with surface exposure dated moraines in the nearby Cordillera Blanca suggest the region preserves a rich record of tropical glaciation. In order to determine the glacial chronology we mapped and dated glacial features of the Jahuacocha valley (which drains the western side of the range) and two eastern drainages, the Mitococha valley, and the Carhuacocha valley. At each locality we used ASTER data, aerial photographs, and GPS to map glacial features both within main valleys and tributaries. We sampled quartz-bearing erratics on moraine crests as well as ice-polished bedrock surfaces for exposure age dating using in situ produced cosmogenic 10Be and 26Al. In the Jahuacocha valley, the greatest ice extent reached an elevation of ˜4090m and moraine crest boulders yield and age of ˜11.2 ±0.6 ka suggesting a significant late Glacial ice advance or stillstand. A younger cluster of moraines exists ˜1 km up-valley at an elevation of ˜4100m. These moraines, dated at ˜8.0 ±1.0 ka, suggest an early Holocene advance. In the Mitococha valley, a young moraine and polished bedrock dated at ˜0.2 ka and ˜11.4 ±0.4 ka respectively span the late Glacial through recent. The late Glacial features of this eastern drainage occur at an elevation of ˜4100m while the recent events occur at an elevation of ˜4380m. Our preliminary results suggest that all three valleys experienced a very similar glacial history with minor differences likely due to the variations in valley morphology. Comparing the chronology of glaciation in the Cordillaera Huayhuash with that in regions to the south and north will provide a means of evaluating the degree of synchroneity of glaciation and climate change across 5° of latitude in the tropics.

Surface water flooding, groundwater contamination, and enteric disease in developed countries: A scoping review of connections and consequences.

PubMed

Andrade, L; O'Dwyer, J; O'Neill, E; Hynds, P

2018-05-01

Significant volumes of research over the past four decades has sought to elucidate the social, infrastructural, economic, and human health effects of climate change induced surface flooding. To date, epidemiological and public health studies of flooding events have focused on mental health effects, vector-borne diseases, and infectious enteric disease due to floodwater contact (i.e. typically low consumption rates). The inherent nature of groundwater (i.e. out of sight, out of mind) and the widely held belief that aquifers represent a pristine source of drinking water due to natural attenuation may represent the "perfect storm" causing direct consumption of relatively large volumes of surface flood-contaminated groundwater. Accordingly, the current study sought to systematically identify and synthesize all available peer-reviewed literature pertaining to the nexus between surface flooding, groundwater contamination and human gastroenteric outcomes. Just 14 relevant studies were found to have been published during the period 1980-2017, thus highlighting the fact that this potentially significant source of climate-related exposure to environmental infection has remained understudied to date. Studies differed significantly in terms of type and data reporting procedures, making it difficult to discern clear trends and patterns. Approximately 945 confirmed cases of flood-related enteric disease were examined across studies; these concurred with almost 10,000 suspected cases, equating to approximately 20 suspected cases per confirmed case. As such, no regional, national or global estimates are available for the human gastrointestinal health burden of flood-related groundwater contamination. In light of the demonstrable public health significance of the concurrent impacts of groundwater susceptibility and climate change exacerbation, strategies to increase awareness about potential sources of contamination and motivate precautionary behaviour (e.g. drinking water testing and treatment, supply interruptions) are necessary. Mainstreaming climate adaptation concerns into planning policies will also be necessary to reduce human exposure to waterborne sources of enteric infection. Copyright © 2018 Elsevier Ltd. All rights reserved.

Extensive MIS 3 glaciation in southernmost Patagonia revealed by cosmogenic nuclide dating of outwash sediments

NASA Astrophysics Data System (ADS)

Darvill, Christopher M.; Bentley, Michael J.; Stokes, Chris R.; Hein, Andrew S.; Rodés, Ángel

2015-11-01

The timing and extent of former glacial advances can demonstrate leads and lags during periods of climatic change and their forcing, but this requires robust glacial chronologies. In parts of southernmost Patagonia, dating pre-global Last Glacial Maximum (gLGM) ice limits has proven difficult due to post-deposition processes affecting the build-up of cosmogenic nuclides in moraine boulders. Here we provide ages for the Río Cullen and San Sebastián glacial limits of the former Bahía Inútil-San Sebastián (BI-SSb) ice lobe on Tierra del Fuego (53-54°S), previously hypothesised to represent advances during Marine Isotope Stages (MIS) 12 and 10, respectively. Our approach uses cosmogenic 10Be and 26Al exposure dating, but targets glacial outwash associated with these limits and uses depth-profiles and surface cobble samples, thereby accounting for surface deflation and inheritance. The data reveal that the limits formed more recently than previously thought, giving ages of 45.6 ka (+139.9/-14.3) for the Río Cullen, and 30.1 ka (+45.6/-23.1) for the San Sebastián limits. These dates indicate extensive glaciation in southern Patagonia during MIS 3, prior to the well-constrained, but much less extensive MIS 2 (gLGM) limit. This suggests the pattern of ice advances in the region was different to northern Patagonia, with the terrestrial limits relating to the last glacial cycle, rather than progressively less extensive glaciations over hundreds of thousands of years. However, the dates are consistent with MIS 3 glaciation elsewhere in the southern mid-latitudes, and the combination of cooler summers and warmer winters with increased precipitation, may have caused extensive glaciation prior to the gLGM.

Pathways from childhood maltreatment to emerging adulthood: investigating trauma-mediated substance use and dating violence outcomes among child protective services-involved youth.

PubMed

Faulkner, Breanne; Goldstein, Abby L; Wekerle, Christine

2014-01-01

Longitudinal survey data were used to examine the relationship between two types of childhood maltreatment, abuse/neglect and exposure to intimate partner violence (IPV), and two outcomes, substance use and dating violence, within the past year. Participants were youth (N = 158, aged 16-19 at Time 3) involved with child protective services (CPS). A parallel multiple mediator model was used to test the hypothesis that trauma symptoms would mediate the relationship between both types of maltreatment and dating violence, marijuana, and alcohol use outcomes. Although both types of maltreatment were not directly associated with dating violence and substance use outcomes, the indirect effects of anxiety, anger, and dissociation on the relationship between maltreatment and substance use/dating violence were significant. Direct effects of both types of maltreatment on past year use of dating violence + alcohol use and dating violence + marijuana use were not significant, but results demonstrated a significant indirect effect for anger on the relationship between exposure to IPV and past year dating violence + marijuana use. No other indirect effects were significant. Findings highlight the negative effects of exposure to IPV and have implications for the development of prevention programming for youth transitioning out of CPS. © The Author(s) 2014.

Asynchronous Glacial Chronologies in the Central Andes (15-40°S) and Paleoclimatic Implications

NASA Astrophysics Data System (ADS)

Zech, R.; Kull, C.; Kubik, P. W.; Veit, H.

2006-12-01

We have established glacial chronologies along a N-S transect over the Central Andes using 10Be surface exposure dating. Our results show that maximum glacial advances occurred asynchronously and reflect the varying influence and shifts of the major atmospheric circulation systems during the Late Quaternary: the tropical circulation in the north and the westerlies in the south. In Bolivia (three research areas in the Cordillera Real and the Cordillera Cochabamba, ~15°S) glacial advances could be dated to ~20 and 12 ka BP. This is in good agreement with published exposure age data from moraines in Bolivia and Peru (provided that all ages are calculated following the same scaling system). Accordingly, the maximum glaciation there probably occurred roughly synchronous to the temperature minimum of the global Last Glacial Maximum (LGM) and the lateglacial cold reversals. Strict correlation with neither the Younger Dryas in the northern hemisphere, nor the Antarctic Cold Reversal is possible due to the current systematic exposure age uncertainties (~10%). Glacier-Climate-Modelling corroborates the sensitivity of the reconstructed glaciers to temperature changes, rather than precipitation. On the contrary, there is good evidence for the dominant role of precipitation changes on the glacial chronologies in the lee of the Cordillera Occidental, i.e. on the Altiplano and further south. The pronounced lateglacial wet phase, which is well documented in lake transgression phases as far south as 28°S (-> tropical moisture source), seems to have caused glacial advances even at ~30°S. In two research areas in Chile at that latitude, we were able to date several lateglacial moraines. Besides, the maximum datable glaciation there occurred at ~30 ka BP. That is significantly earlier than the LGM (sensu strictu) and points to favourable climate conditions for glaciation at that time (particularly increased precipitation). We conclude that the westerlies were more intensive or shifted northward at ~30 ka BP. We have not yet been able to date LGM moraines as far south as ~40°, which would indicate the transition of precipitation- to temperature-sensitive glaciers. Instead, our preliminary exposure age chronology from Valle Rucachoroi (~39°S, Argentina) suggests that the maximum glaciation there occurred also at ~30 ka BP, but that the valleys became ice-free only by ~15 ka BP. Samples from moraines in the cirques are currently in progress and may document lateglacial re-advances.

Surface Exposure Dating of the Huancané III Moraines in Peru: A Record of Quelccaya Ice Cap's Maximum Extent during the Last Glacial Period

NASA Astrophysics Data System (ADS)

Baranes, H. E.; Kelly, M. A.; Stroup, J. S.; Howley, J. A.; Lowell, T. V.

2012-12-01

The climatic conditions that influenced the tropics during the height of the last glacial period are not well defined and controversial. There are disparities in estimates of temperature anomalies (e.g., MARGO, 2009; Rind and Peteet, 1985; CLIMAP, 1976), and critical terrestrial paleotemperature proxy records in tropical regions are poorly dated (e.g., Porter, 2001). Defining these conditions is important for understanding the mechanisms that cause major shifts in climate, as the tropics are a primary driver of atmospheric and oceanic circulation. This study aims to constrain the timing of maximum glacier extents in the Cordillera Oriental in southern Peru during the last glacial period by applying surface exposure (beryllium-10) dating to the Huancané III (Hu-III) moraines. The Hu-III moraines mark the maximum extent of Quelccaya Ice Cap (QIC) (13.93°S, 70.83°W), the largest tropical ice cap, during the last ice age. The eight beryllium-10 ages presented here yield 17,056 ± 520 yrs ago as a minimum age for the onset of recession from the ice cap advance marked by the Hu-III moraines. Comparing this age to other paleoclimate records indicates that the ice cap advance marked by the Hu-III moraines is more likely associated with a North Atlantic climate event known as Heinrich I (H1; 16,800 yrs ago, Bond et al., 1992, 1993) than with global cooling at the Last Glacial Maximum (LGM; ~21,000 yrs ago, Denton and Hughes, 1981). This result suggests that climate processes in the North Atlantic region are linked to climatic conditions in the tropical Andes. A mesoscale climate model and an ice-flow model are currently being developed for QIC. The moraine data presented in this study will be used with these two models to test response of QIC to North Atlantic and global climate events.

Linking glacial erosion and low-relief landscapes in tropical orogens

NASA Astrophysics Data System (ADS)

Cunningham, M.; Stark, C. P.; Kaplan, M. R.; Schaefer, J. M.; Galewsky, J.; Yoo, J.

2015-12-01

One significant way that climate influences orogenic evolution is by modulating glacial erosion. At mid-latitudes it is hypothesized that this climate-tectonic interplay is so strong that a "glacial buzzsaw" acting throughout the Quaternary outpaced tectonic uplift in most mountain belts and concentrated topography in a zone defined by the bounds of ELA fluctuation. Less attention has been paid to how the buzzsaw might manifest itself at low latitudes, where many mountain belts are just high enough to have been glaciated at the LGM but today sit well below the ELA. We have focused on the glacial history of Costa Rica and Taiwan, where we find evidence of ice cap erosion coincident with low-relief landscapes near the LGM ELA. Previous attempts to understand the formation of these perched, low-relief landscapes has mostly concerned interactions between fluvial erosion and geodynamics. Our work aims instead to describe the role that glacial erosion played in the evolution of these landscapes, and how they fit in the buzzsaw paradigm. At Cerro Chirripó in Costa Rica we use 10-Be surface exposure age dating of moraine boulders and scoured bedrock, field mapping, and remote sensing to constrain the timing, areal extent, and pattern of glacial erosion. We made similar observations of ice extent at Nanhudashan in Taiwan, where surface exposure age dating has previously been applied to glacial landforms (e.g. Hebenstreit et al., 2011; Siame et al., 2007). In Costa Rica, our 10-Be dates from scoured bedrock near the highest peak and terminal/lateral moraines show signs of ice-cap erosion until 22 ka. Similar arguments for LGM ice cap erosion have been made for Nanhudashan. Regional climate simulations (WRF) further constrain the timing and spatial extent of glaciation in these places, and the combination of field data and climate modeling will inform estimates of the magnitude of glacial erosion on perched landscapes.

Exposure pathway evaluations for sites that processed asbestos-contaminated vermiculite.

PubMed

Anderson, Barbara A; Dearwent, Steve M; Durant, James T; Dyken, Jill J; Freed, Jennifer A; Moore, Susan McAfee; Wheeler, John S

2005-01-01

The Agency for Toxic Substances and Disease Registry (ATSDR) is currently evaluating the potential public health impacts associated with the processing of asbestos-contaminated vermiculite at various facilities around the country. Vermiculite ore contaminated with significant levels of asbestos was mined and milled in Libby, Montana, from the early 1920s until 1990. The majority of the Libby ore was then shipped to processing facilities for exfoliation. ATSDR initiated the National Asbestos Exposure Review (NAER) to identify and evaluate exposure pathways associated with these processing facilities. This manuscript details ATSDR's phased approach in addressing exposure potential around these sites. As this is an ongoing project, only the results from a selected set of completed site analyses are presented. Historical occupational exposures are the most significant exposure pathway for the site evaluations completed to date. Former workers also probably brought asbestos fibers home on their clothing, shoes, and hair, and their household contacts may have been exposed. Currently, most site-related worker and community exposure pathways have been eliminated. One community exposure pathway of indeterminate significance is the current exposure of individuals through direct contact with waste rock brought home for personal use as fill material, driveway surfacing, or soil amendment. Trace levels of asbestos are present in soil at many of the sites and buried waste rock has been discovered at a few sites; therefore, future worker and community exposure associated with disturbing on-site soil during construction or redevelopment at these sites is also a potential exposure pathway.

User guide for luminescence sampling in archaeological and geological contexts

USGS Publications Warehouse

Nelson, Michelle S.; Gray, Harrison J.; Johnson, Jack A.; Rittenour, Tammy M.; Feathers, James K.; Mahan, Shannon

2015-01-01

Luminescence dating provides a direct age estimate of the time of last exposure of quartz or feldspar minerals to light or heat and has been successfully applied to deposits, rock surfaces, and fired materials in a number of archaeological and geological settings. Sampling strategies are diverse and can be customized depending on local circumstances, although all sediment samples need to include a light-safe sample and material for dose-rate determination. The accuracy and precision of luminescence dating results are directly related to the type and quality of the material sampled and sample collection methods in the field. Selection of target material for dating should include considerations of adequacy of resetting of the luminescence signal (optical and thermal bleaching), the ability to characterize the radioactive environment surrounding the sample (dose rate), and the lack of evidence for post-depositional mixing (bioturbation in soils and sediment). Sample strategies for collection of samples from sedimentary settings and fired materials are discussed. This paper should be used as a guide for luminescence sampling and is meant to provide essential background information on how to properly collect samples and on the types of materials suitable for luminescence dating.

Violence exposure and teen dating violence among African American youth.

PubMed

Black, Beverly M; Chido, Lisa M; Preble, Kathleen M; Weisz, Arlene N; Yoon, Jina S; Delaney-Black, Virginia; Kernsmith, Poco; Lewandowski, Linda

2015-07-01

This study examines the relationships between exposure to violence in the community, school, and family with dating violence attitudes and behaviors among 175 urban African American youth. Age, gender, state support and experiences with neglect, school violence, and community violence were the most significant predictors of acceptance of dating violence. Experiences with community violence and age were important predictors of dating violence perpetration and victimization. Findings highlight the importance of planning prevention programs that address variables affecting attitudes and behaviors of high-risk youth who have already been exposed to multiple types of violence. © The Author(s) 2014.

The last glaciation of Bear Peninsula, central Amundsen Sea Embayment of Antarctica: Constraints on timing and duration revealed by in situ cosmogenic 14C and 10Be dating

NASA Astrophysics Data System (ADS)

Johnson, Joanne S.; Smith, James A.; Schaefer, Joerg M.; Young, Nicolás E.; Goehring, Brent M.; Hillenbrand, Claus-Dieter; Lamp, Jennifer L.; Finkel, Robert C.; Gohl, Karsten

2017-12-01

Ice streams in the Pine Island-Thwaites region of West Antarctica currently dominate contributions to sea level rise from the Antarctic ice sheet. Predictions of future ice-mass loss from this area rely on physical models that are validated with geological constraints on past extent, thickness and timing of ice cover. However, terrestrial records of ice sheet history from the region remain sparse, resulting in significant model uncertainties. We report glacial-geological evidence for the duration and timing of the last glaciation of Hunt Bluff, in the central Amundsen Sea Embayment. A multi-nuclide approach was used, measuring cosmogenic 10Be and in situ14C in bedrock surfaces and a perched erratic cobble. Bedrock 10Be ages (118-144 ka) reflect multiple periods of exposure and ice-cover, not continuous exposure since the last interglacial as had previously been hypothesized. In situ14C dating suggests that the last glaciation of Hunt Bluff did not start until 21.1 ± 5.8 ka - probably during the Last Glacial Maximum - and finished by 9.6 ± 0.9 ka, at the same time as ice sheet retreat from the continental shelf was complete. Thickening of ice at Hunt Bluff most likely post-dated the maximum extent of grounded ice on the outer continental shelf. Flow re-organisation provides a possible explanation for this, with the date for onset of ice-cover at Hunt Bluff providing a minimum age for the timing of convergence of the Dotson and Getz tributaries to form a single palaeo-ice stream. This is the first time that timing of onset of ice cover has been constrained in the Amundsen Sea Embayment.

Inhibitory effect of double atmospheric pressure argon cold plasma on spores and mycotoxin production of Aspergillus niger contaminating date palm fruits.

PubMed

Ouf, Salama A; Basher, Abdulrahman H; Mohamed, Abdel-Aleam H

2015-12-01

Aspergillus niger has been reported as a potentially dangerous pathogen of date-palm fruits in Saudi Arabia due to the production of fumonisin B2 (FB2 ) and ochratoxin A (OTA). In a trial to disinfect this product, a double atmospheric pressure argon cold plasma (DAPACP) jet system was set up and evaluated against spore germination and mycotoxin production of the pathogen. The plasma jets were characterised photographically, electrically and spectroscopically. DAPACP jet length increases with the increase of argon flow rate, with optimum rate at 3.5 L min(-1) . The viability of A. niger spores, inoculated onto sterilised date palm fruit discs, progressively decreases with extension of the exposure time of DAPACP due to the more quantitative amount of OH and O radicals interacting with the examined samples. There was a progressive reduction of the amount of FB2 and OTA detected in date palm discs on extension of the exposure time of the plasma-treated inoculums at flow rate of 3.5 L min(-1) . FB2 was not detected in the discs inoculated with 6-min plasma-treated A. niger, while OTA was completely absent when the fungus was treated for 7.5 min. DAPACP showed promising results in dry fruit decontamination and in inhibition of mycotoxin release by A. niger contaminating the fruits. The progress in the commercial application of cold plasma needs further investigation concerning the ideal width of the plasma output to enable it to cover wider surfaces of the sample and consequently inducing greater plasma performance. © 2014 Society of Chemical Industry.

Relict colluvial boulder deposits as paleoclimatic indicators in the Yucca Mountain region, southern Nevada

USGS Publications Warehouse

Whitney, J.W.; Harrington, C.D.

1993-01-01

Early to middle Pleistocene boulder deposits are common features on southern Nevada hillslopes. These darkly varnished, ancient colluvial deposits stand out in stark contrast to the underlying light-colored bedrock of volcanic tuffs, and they serve as minor divides between drainage channels on modern hillslopes. To demonstrate the antiquity of these stable hillslope features, six colluvial boulder deposits from Yucca Mountain, Nye County, Nevada, were dated by cation-ratio dating of rock varnish accreted on boulder surfaces. Estimated minimum ages of these boulder deposits range from 760 to 170 ka. Five additional older deposits on nearby Skull and Little Skull Mountains and Buckboard Mesa yielded cation-ratio minimum-age estimates of 1.38 Ma to 800 ka. An independent cosmogenic chlorine-36 surface exposure date was obtained on one deposit, which confirms an estimated early to middle Quaternary age. These deposits have provided the oldest age estimates for unconsolidated hillslope deposits in the southwestern United States. We suggest that the colluvial boulder deposits were produced during early and middle Pleistocene glacial/pluvial episodes and were stabilized during the transition to drier interglacial climates. The preservation of old, thin hillslope deposits and the less-than-2-m incision by hillslope runoff adjacent to these deposits, indicate that extremely low denudation rates have occurred on resistant volcanic hillslopes in the southern Great Basin during Quaternary time. -from Authors

Preliminary Cosmogenic Surface Exposure Ages on Laurentide Ice-sheet Retreat and Opening of the Eastern Lake Agassiz Outlets

NASA Astrophysics Data System (ADS)

Leydet, D.; Carlson, A. E.; Sinclair, G.; Teller, J. T.; Breckenridge, A. J.; Caffee, M. W.; Barth, A. M.

2015-12-01

The chronology for the eastern outlets of glacial Lake Agassiz holds important consequences for the cause of Younger Dryas cold event during the last deglaciation. Eastward routing of Lake Agassiz runoff was originally hypothesized to have triggered the Younger Dryas. However, currently the chronology of the eastern outlets is only constrained by minimum-limiting radiocarbon ages that could suggest the eastern outlets were still ice covered at the start of the Younger Dryas at ~12.9 ka BP, requiring a different forcing of this abrupt climate event. Nevertheless, the oldest radiocarbon ages are still consistent with an ice-free eastern outlet at the start of the Younger Dryas. Here we will present preliminary 10-Be cosmogenic surface exposure ages from the North Lake, Flat Rock Lake, glacial Lake Kaministiquia, and Lake Nipigon outlets located near Thunder Bay, Ontario. These ages will date the timing of the deglaciation of the Laurentide ice sheet in the eastern outlet region of glacial Lake Agassiz. This will provide an important constraint for the hypothesized freshwater forcing of the cause of Younger Dryas cold event.

The CREp program, a fully parameterizable program to compute exposure ages (3He, 10Be)

NASA Astrophysics Data System (ADS)

Martin, L.; Blard, P. H.; Lave, J.; Delunel, R.; Balco, G.

2015-12-01

Over the last decades, cosmogenic exposure dating permitted major advances in Earth surface sciences, and particularly in paleoclimatology. Yet, exposure age calculation is a dense procedure. It requires numerous choices of parameterization and the use of an appropriate production rate. Nowadays, Earth surface scientists may either calculate exposure ages on their own or use the available programs. However, these programs do not offer the possibility to include all the most recent advances in Cosmic Ray Exposure (CRE) dating. Notably, they do not propose the most recent production rate datasets and they only offer few possibilities to test the impact of the atmosphere model and the geomagnetic model on the computed ages. We present the CREp program, a Matlab © code that computes CRE ages for 3He and 10Be over the last 2 million years. The CREp program includes the scaling models of Lal-Stone in the "Lal modified" version (Balco et al., 2008; Lal, 1991; Stone, 2000) and the LSD model (Lifton et al., 2014). For any of these models, CREP allows choosing between the ERA-40 atmosphere model (Uppala et al., 2005) and the standard atmosphere (National Oceanic and Atmospheric Administration, 1976). Regarding the geomagnetic database, users can opt for one of the three proposed datasets: Muscheler et al. 2005, GLOPIS-75 (Laj et al. 2004) and the geomagnetic framework proposed in the LSD model (Lifton et al., 2014). They may also import their own geomagnetic database. Importantly, the reference production rate can be chosen among a large variety of possibilities. We made an effort to propose a wide and homogenous calibration database in order to promote the use of local calibration rates: CREp includes all the calibration data published until July 2015 and will be able to access an updated online database including all the newly published production rates. This is crucial for improving the ages accuracy. Users may also choose a global production rate or use their own data to either calibrate a production rate or directly input a Sea Level High Latitude value. The program is fast to calculate a large number of ages and to export the final density probability function associated with each age into an Excel © spreadsheet format.

Rock Formation and Cosmic Radiation Exposure Ages in Gale Crater Mudstones from the Mars Science Laboratory

NASA Astrophysics Data System (ADS)

Mahaffy, Paul; Farley, Ken; Malespin, Charles; Gellert, Ralph; Grotzinger, John

2014-05-01

The quadrupole mass spectrometer (QMS) in the Sample Analysis at Mars (SAM) suite of the Mars Science Laboratory (MSL) has been utilized to secure abundances of 3He, 21Ne, 36Ar, and 40Ar thermally evolved from the mudstone in the stratified Yellowknife Bay formation in Gale Crater. As reported by Farley et al. [1] these measurements of cosmogenic and radiogenic noble gases together with Cl and K abundances measured by MSL's alpha particle X-ray spectrometer enable a K-Ar rock formation age of 4.21+0.35 Ga to be established as well as a surface exposure age to cosmic radiation of 78+30 Ma. Understanding surface exposures to cosmic radiation is relevant to the MSL search for organic compounds since even the limited set of studies carried out, to date, indicate that even 10's to 100's of millions of years of near surface (1-3 meter) exposure may transform a significant fraction of the organic compounds exposed to this radiation [2,3,4]. Transformation of potential biosignatures and even loss of molecular structural information in compounds that could point to exogenous or endogenous sources suggests a new paradigm in the search for near surface organics that incorporates a search for the most recently exposed outcrops through erosional processes. The K-Ar rock formation age determination shows promise for more precise in situ measurements that may help calibrate the martian cratering record that currently relies on extrapolation from the lunar record with its ground truth chronology with returned samples. We will discuss the protocol for the in situ noble gas measurements secured with SAM and ongoing studies to optimize these measurements using the SAM testbed. References: [1] Farley, K.A.M Science Magazine, 342, (2013). [2] G. Kminek et al., Earth Planet Sc Lett 245, 1 (2006). [3] Dartnell, L.R., Biogeosciences 4, 545 (2007). [4] Pavlov, A. A., et al. Geophys Res Lett 39, 13202 (2012).

Glass composition development for stabilization of lead based paints

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

Marra, J.C.

1996-10-01

Exposure to lead can lead to adverse health affects including permanent damage to the central nervous system. Common means of exposure to lead are from ingestion of lead paint chips or breathing of dust from deteriorating painted surfaces. The U.S. Army has over 101 million square feet of buildings dating to World War II or earlier. Many of these structures were built before the 1978 ban on lead based paints. The U.S. Army Corps of Engineers CERL is developing technologies to remove and stabilize lead containing organic coatings. Promising results have been achieved using a patented flame spray process thatmore » utilizes a glass frit to stabilize the hazardous constituents. When the glass frit is sprayed onto the paint containing substrate, differences in thermal expansion coefficients between the frit and the paint results in spalling of the paint from the substrate surface. The removed fragments are then collected and remelted to stabilize the hazardous constituents and allow for disposal as non-hazardous waste. Similar successful results using a patented process involving microwave technology for paint removal have also been achieved. In this process, the painted surface is coated with a microwave coupling compound that when exposed to microwave energy results in the spalling of the hazardous paint from the surface. The fragments can again be accumulated and remelted for stabilization and disposal.« less

Regolith Depth, Mobility, and Variability on Vesta from Dawn's Low Altitude Mapping Orbit

NASA Technical Reports Server (NTRS)

Denevi, B. W.; Coman, E. I.; Blewett, D. T.; Mittlefehldt, D. W.; Buczkowski, D. L.; Combe, J.-P.; De Sanctis, M. C.; Jaumann, R.; Li, J.-Y.; Marchi, S.;

Schmidt-hammer exposure-age dating (SHD) of Lateglacial rock glacier systems near the eastern margin of the European Alps

NASA Astrophysics Data System (ADS)

Kellerer-Pirklbauer, Andreas

2016-04-01

Rock glaciers are widespread permafrost landforms in Austria. Various rock glacier inventories list more than 4500 rock glaciers in the country; some 30-40% of them are intact. Relict (permafrost free) and pseudo-relict rock glaciers (sporadic and isolated permafrost particularly near the root zone) prevail in number. Rock glaciers are commonly formed over a period of several ka. Dating such landforms helps to understand palaeoclimatic conditions. In this study three rock glaciers consisting of gneiss were dated applying the Schmidt-hammer exposure-age dating (SHD) method. The rock glaciers are located at three neighbouring cirques in the Seckauer Tauern Range named Reichart Rock Glacier (RRG, area 1.26 km², length 1800 m, elevation range 1520-1940 m a.s.l.), Schöneben Rock Glacier (SRG, 0.11 km², 750 m, 1715-1905 m a.s.l.), and Dürrtal Rock Glacier (DRG, 0.08 km², 850 m, 1750-1980 m a.s.l.). RRG is one of the largest rock glaciers in Austria. All three landforms are influenced by lenses of permafrost at present (as indicated by ERT). During the LGM the Seckauer Tauern were covered by valley glaciers and deglaciation occurred presumably already early in the Alpine Lateglacial period. An analogue N-type Schmidt-hammer (proceq) was used for measuring the surface strength of stable blocks at the rock glacier surface by recording a rebound value (R-value) of a spring-loaded bolt. The R-value gives a relative measure of the surface hardness and hence time since exposure to weathering. Eight (RRG) or six (SRG, DRG) Schmidt-hammer measurement sites (with 50-100 individual readings) aligned along longitudinal transects (=former central flow line) between a talus slope (with relatively fresh boulders) in the root zone and the frontal ridge were measured. Mean R-value differences of 30.5 at RRG, 25.1 at SRG, and 20.7 at DRG were revealed along the three transects. The differences between the lowest and the highest R-value at the rock glaciers itself were 19.0 at RRG, 15.2 at SRG, and 10.5 at DRG. The differences in R-values between the talus slopes and the uppermost Schmidt-hammer site at the rock glacier were 11.5 at RRG, 9.9 at SRG, and 10.2 at DRG. No high-quality age control points are available at the studied rock glacier. Therefore, an age-calibration curve cannot be established. An age-calibration curve for gneiss has been established previously for a rock glacier c.110 km west of the study area yielding a mean decrease of 1.46 R/1 ka. This allows the estimate that the rock glacier formation period in the study area stretched over a period of several ka. Not unlikely, the formation of the rock glaciers was initiated already during the Gschnitz stadial (Heinrich 1 ice rafting event) dated to 15.4 ka BP or even earlier. SRG is the oldest rock glacier possibly starting to form during the later part of the Lateglacial ice decay-phase. At least 7-8 ka ago the stabilisation of the uppermost part of the three rock glaciers was accomplished. This rather late stabilisation might be also related to the thermally inert response of coarse rock glacier systems.

Solar Ion Processing of Itokawa Grains: Constraints on Surface Exposure Times

NASA Technical Reports Server (NTRS)

Christoffersen, R.; Keller, L. P.

2015-01-01

Analytical TEM observations obtained to date reveal that a significant sub-population of grains returned from the surface of asteroid Itokawa have had their outer 30-100 nm processed by space weathering effects. Although the effects include some surface deposition of condensed impact vapor and isolated impact melt splashes, much of the width of the space weathered outer margins or "rims" on grains is derived from solar wind processing of the original host grain. Similar to what has long been reported for some lunar grains, the ion-processed rims on Itokawa grains exhibit varing degrees and depths of penetration of atomic-displacement ion damage, resulting in complete amorphization for some rims (particularly in plagioclase), or formation of highly defective but still crystalline structures in others (particularly in pyroxene and olivine). Possibly different from lunar grains, however, is the presence of isolated internal cavities or voids in Itokawa grain rims, which may be implantation "bubbles" due to accumulating implanted solar wind H and/or He. For a given mineral exposed at a particular set of long term solar wind conditions, the level of ion damage in a given grain rim, the depth of damage penetration represented by the rim width, and the formation or lack of formation of implantation bubbles can all be linked to the time spent by the grain in an uncovered state on the topmost, space-exposed, regolith surface. For the lunar case, we have previously shown that with reasonable assumptions about solar wind characteristics over time, a model can be developed to estimate this exposure time based on the width of amorphous rims on lunar grains. Here we report on an expansion of the model to cover exposure time information contained in the array of solar ion-induced features in Itokawa grains.

Youth experiences of family violence and teen dating violence perpetration: cognitive and emotional mediators.

PubMed

Jouriles, Ernest N; McDonald, Renee; Mueller, Victoria; Grych, John H

2012-03-01

This article describes a conceptual model of cognitive and emotional processes proposed to mediate the relation between youth exposure to family violence and teen dating violence perpetration. Explicit beliefs about violence, internal knowledge structures, and executive functioning are hypothesized as cognitive mediators, and their potential influences upon one another are described. Theory and research on the role of emotions and emotional processes in the relation between youths' exposure to family violence and teen dating violence perpetration are also reviewed. We present an integrated model that highlights how emotions and emotional processes work in tandem with hypothesized cognitive mediators to predict teen dating violence.

Extent of the last ice sheet in northern Scotland tested with cosmogenic 10Be exposure ages

USGS Publications Warehouse

Phillips, W.M.; Hall, A.M.; Ballantyne, C.K.; Binnie, S.; Kubik, P.W.; Freeman, S.

2008-01-01

The extent of the last British-Irish Ice Sheet (BIIS) in northern Scotland is disputed. A restricted ice sheet model holds that at the global Last Glacial Maximum (LGM; ca. 23-19 ka) the BIIS terminated on land in northern Scotland, leaving Buchan, Caithness and the Orkney Islands ice-free. An alternative model implies that these three areas were ice-covered at the LGM, with the BIIS extending offshore onto the adjacent shelves. We test the two models using cosmogenic 10Be surface exposure dating of erratic boulders and glacially eroded bedrock from the three areas. Our results indicate that the last BIIS covered all of northern Scotland during the LGM, but that widespread deglaciation of Caithness and Orkney occurred prior to rapid warming at ca. 14.5 ka. Copyright ?? 2008 John Wiley & Sons, Ltd.

Space Shuttle Pad Exposure Period Meteorological Parameters STS-1 Through STS-107

NASA Technical Reports Server (NTRS)

Overbey, B. G.; Roberts, B. C.

2005-01-01

During the 113 missions of the Space Transportation System (STS) to date, the Space Shuttle fleet has been exposed to the elements on the launch pad for approx. 4,195 days. The Natural Environments Branch at Marshall Space Flight Center archives atmospheric environments to which the Space Shuttle vehicles are exposed. This Technical Memorandum (TM) provides a summary of the historical record of the meteorological conditions encountered by the Space Shuttle fleet during the pad exposure period. Parameters included in this TM are temperature, relative humidity, wind speed, wind direction, sea level pressure, and precipitation. Extremes for each of these parameters for each mission are also summarized. Sources for the data include meteorological towers and hourly surface observations. Data are provided from the first launch of the STS in 1981 through the launch of STS-107 in 2003.

Lunar regolith dynamics based on analysis of the cosmogenic radionuclides Na-22, Al-26, and Mn-53

NASA Technical Reports Server (NTRS)

Fruchter, J. S.; Rancitelli, L. A.; Laul, J. C.; Perkins, R. W.

1977-01-01

Depth profiles of Na-22 and Al-26 in the upper portions of five lunar cores are analyzed. From the analyses, it is concluded that the natural gardening processes on the lunar surface result in mixing of the regolith to a depth of 2-3 cm over a time period which is short compared with the half-life of Al-26 (0.73 m.y.). It is also concluded that the rotary drill processes which were used to obtain the deep drill samples generally resulted in loss and/or mixing of the upper portions of the cores. In contrast, the near-surface regions of the drive tube cores appear to have a well-preserved stratigraphy. Analysis of Mn-53 in samples of six lunar rocks helps substantiate the accuracy of age date estimates by other means, and provides definite information that the total lunar surface exposure of two of these rocks has occurred during a single surface event which continued to their collection.

Late glacial and Holocene history of the Greenland Ice Sheet margin, Nunatarssuaq, Northwestern Greenland

NASA Astrophysics Data System (ADS)

Farnsworth, L. B.; Kelly, M. A.; Axford, Y.; Bromley, G. R.; Osterberg, E. C.; Howley, J. A.; Zimmerman, S. R. H.; Jackson, M. S.; Lasher, G. E.; McFarlin, J. M.

2015-12-01

Defining the late glacial and Holocene fluctuations of the Greenland Ice Sheet (GrIS) margin, particularly during periods that were as warm or warmer than present, provides a longer-term perspective on present ice margin fluctuations and informs how the GrIS may respond to future climate conditions. We focus on mapping and dating past GrIS extents in the Nunatarssuaq region of northwestern Greenland. During the summer of 2014, we conducted geomorphic mapping and collected rock samples for 10Be surface exposure dating as well as subfossil plant samples for 14C dating. We also obtained sediment cores from an ice-proximal lake. Preliminary 10Be ages of boulders deposited during deglaciation of the GrIS subsequent to the Last Glacial Maximum range from ~30-15 ka. The apparently older ages of some samples indicate the presence of 10Be inherited from prior periods of exposure. These ages suggest deglaciation occurred by ~15 ka however further data are needed to test this hypothesis. Subfossil plants exposed at the GrIS margin on shear planes date to ~ 4.6-4.8 cal. ka BP and indicate less extensive ice during middle Holocene time. Additional radiocarbon ages from in situ subfossil plants on a nunatak date to ~3.1 cal. ka BP. Geomorphic mapping of glacial landforms near Nordsø, a large proglacial lake, including grounding lines, moraines, paleo-shorelines, and deltas, indicate the existence of a higher lake level that resulted from a more extensive GrIS margin likely during Holocene time. A fresh drift limit, characterized by unweathered, lichen-free clasts approximately 30-50 m distal to the modern GrIS margin, is estimated to be late Holocene in age. 10Be dating of samples from these geomorphic features is in progress. Radiocarbon ages of subfossil plants exposed by recent retreat of the GrIS margin suggest that the GrIS was at or behind its present location at AD ~1650-1800 and ~1816-1889. Results thus far indicate that the GrIS margin in northwestern Greenland responded sensitively to Holocene climate changes. Ongoing research will improve the chronological constraints on these fluctuations.

Investigations of lunar materials

NASA Technical Reports Server (NTRS)

Comstock, G. M.; Fvwaraye, A. O.; Fleischer, R. L.; Hart, H. R., Jr.

1972-01-01

The investigations were directed at determining the radiation history and surface chronology of lunar materials using the etched particle track technique. The major lunar materials studied are the igneous rocks and double core from Apollo 12, the breccia and soil samples from Apollo 14, and the core samples from Luna 16. In the course of this work two new and potentially important observations were made: (1) Cosmic ray-induced spallation-recoil tracks were identified. The density of such tracks, when compared with the density of tracks induced by a known flux of accelerator protons, yields the time of exposure of a sample within the top meter or two of moon's surface. (2) Natural, fine scale plastic deformation was found to have fragmented pre-existing charged particle tracks, allowing the dating of the mechanical event causing the deformation.

Substance use as a longitudinal predictor of the perpetration of teen dating violence.

PubMed

Temple, Jeff R; Shorey, Ryan C; Fite, Paula; Stuart, Gregory L; Le, Vi Donna

2013-04-01

The prevention of teen dating violence is a major public health priority. However, the dearth of longitudinal studies makes it difficult to develop programs that effectively target salient risk factors. Using a school-based sample of ethnically diverse adolescents, this longitudinal study examined whether substance use (alcohol, marijuana, and hard drugs) and exposure to parental violence predicted the perpetration of physical dating violence over time. 1,042 9th and 10th grade high schools students were recruited and assessed in the spring of 2010, and 93 % of the original sample completed the 1-year follow-up in the spring of 2011. Participants who had begun dating at the initial assessment and who self-identified as African American (n = 263; 32 %), Caucasian (n = 272; 33 %), or Hispanic (n = 293; 35 %) were included in the current analyses (n = 828; 55 % female). Slightly more than half of the adolescents who perpetrated dating violence at baseline reported past year dating violence at follow-up, relative to only 11 % of adolescents who did not report perpetrating dating violence at baseline. Structural equation modeling revealed that the use of alcohol and hard drugs at baseline predicted the future perpetration of physical dating violence, even after accounting for the effects of baseline dating violence and exposure to interparental violence. Despite differences in the prevalence of key variables between males and females, the longitudinal associations did not vary by gender. With respect to race, exposure to mother-to-father violence predicted the perpetration of dating violence among Caucasian adolescents. Findings from the current study indicate that targeting substance use, and potentially youth from violent households, may be viable approaches to preventing the perpetration of teen dating violence.

Substance Use as a Longitudinal Predictor of the Perpetration of Teen Dating Violence

PubMed Central

Shorey, Ryan C.; Fite, Paula; Stuart, Gregory; Le, Vi Donna

2013-01-01

The prevention of teen dating violence is a major public health priority. However, the dearth of longitudinal studies makes it difficult to develop programs that effectively target salient risk factors. Using a school-based sample of ethnically diverse adolescents, this longitudinal study examined whether substance use (alcohol, marijuana, and hard drugs) and exposure to parental violence predicted the perpetration of physical dating violence over time. 1,042 9th and 10th grade high schools students were recruited and assessed in the spring of 2010, and 93% of the original sample completed the 1-year follow-up in the spring of 2011. Participants who had begun dating at the initial assessment and who self-identified as African American (n = 263; 32%), Caucasian (n = 272; 33%), or Hispanic (n = 293; 35%) were included in the current analyses (n = 828; 55% female). Slightly more than half of the adolescents who perpetrated dating violence at baseline reported past year dating violence at follow-up, relative to only 11% of adolescents who did not report perpetrating dating violence at baseline. Structural equation modeling revealed that the use of alcohol and hard drugs at baseline predicted the future perpetration of physical dating violence, even after accounting for the effects of baseline dating violence and exposure to interparental violence. Despite differences in the prevalence of key variables between males and females, the longitudinal associations did not vary by gender. With respect to race, exposure to mother-to-father violence predicted the perpetration of dating violence among Caucasian adolescents. Findings from the current study indicate that targeting substance use, and potentially youth from violent households, may be viable approaches to preventing the perpetration of teen dating violence. PMID:23187699

Effects of Cognitive Distortions on the Link Between Dating Violence Exposure and Substance Problems in Clinically Hospitalized Youth.

PubMed

Miller, Adam Bryant; Williams, Caitlin; Day, Catherine; Esposito-Smythers, Christianne

2017-06-01

The purpose of the present study was to examine whether cognitive distortions (e.g., cognitive errors; negative views of self, world, and future) influence the association between dating violence and problematic substance use behaviors in a sample of psychiatrically hospitalized adolescents. Participants included 155 adolescents, aged 13-17 years, who had initiated dating. Adolescents completed measures of dating violence, substance-related problems (alcohol and marijuana), and cognitive distortions. Logistic regressions were conducted to examine the direct and interactive effects of dating violence exposure and cognitive distortions on likelihood of recent problematic substance use. Results suggested a main effect of dating violence on problematic alcohol and other drug use as well as an interactive effect of dating violence and cognitive distortions. Specifically, the relationship between dating violence and odds of substance-related problems was higher among those with greater (vs. fewer) cognitive distortions. Study results suggest the need for careful screening of cognitive distortions among adolescent dating violence victims, particularly those in mental health treatment. © 2016 Wiley Periodicals, Inc.

Effects of Cognitive Distortions on the Link Between Dating Violence Exposure and Substance Problems in Clinically Hospitalized Youth

PubMed Central

Miller, Adam Bryant; Williams, Caitlin; Esposito-Smythers, Christianne

2016-01-01

Purpose The purpose of the present study was to examine whether cognitive distortions (e.g., cognitive errors; negative views of self, world, and future) influence the association between dating violence and problematic substance use behaviors in a sample of psychiatrically hospitalized adolescents. Methods Participants included 155 adolescents, ages 13 to 17, who had initiated dating. Adolescents completed measures of dating violence, substance related problems, (alcohol and marijuana), and cognitive distortions. Results Logistic regressions were conducted to examine the direct and interactive effects of dating violence exposure and cognitive distortions on likelihood of recent problematic substance use. Results suggested a main effect of dating violence on problematic alcohol and other drug use as well as an interactive effect of dating violence and cognitive distortions. Specifically, the relationship between dating violence and odds of substance related problems were higher among those with greater (vs. fewer) cognitive distortions. Conclusions Study results suggest the need for careful screening of cognitive distortions among adolescent dating violence victims, particularly those in mental health treatment. PMID:27552530

Climate-driven sediment aggradation and incision phases since the Late Pleistocene in the NW Himalaya, India

NASA Astrophysics Data System (ADS)

Dey, Saptarshi; Thiede, Rasmus C.; Schildgen, Taylor F.; Wittmann, Hella; Bookhagen, Bodo; Scherler, Dirk; Jain, Vikrant; Strecker, Manfred R.

2016-04-01

Deciphering the response of sediment routing systems to climatic forcing is fundamental for understanding the impacts of climate change on landscape evolution and depositional systems. In the Sub-Himalaya, late Pleistocene to Holocene alluvial fills and fluvial terraces record periodic fluctuations of sediment supply and transport capacity on timescale of 103 to 105 years, most likely related to past climatic fluctuations. To evaluate the climatic control on sediment supply and transport capacity, we analyze remnant alluvial fans and terraces in the Kangra Basin of the northwestern Sub-Himalaya. Based on field observations and OSL and CRN-dating, we recognized two sedimentary cycles with major sediment aggradation and subsequent re-incision phases. The large one developed over the entire last glacial period with ˜200 m high alluvial fan (AF1) and the second one during the latest Pleistocene/Holocene with ˜50 m alluvial fan (AF2) and its re-incision . Surface-exposure dating of six terrace levels with in-situ cosmogenic nuclides (10Be) indicates the onset of channel abandonment and ensuing incision phases. Two terrace surfaces from the highest level (T1) sculpted into the oldest-preserved AF1 dates back to 48.9 ± 4.1 ka and 42.1 ± 2.7 ka (2σ error). T2 surfaces sculpted into the remnants of AF1 have exposure ages of 16.8 ± 2 ka and 14.1 ± 0.9 ka, while terraces sculpted into the late Pleistocene- Holocene fan (AF2) provide ages of 8.4± 0.8 ka, 6.6± 0.7 ka, 4.9± 0.4 ka and 3.1± 0.3 ka. Together with previously-published ages on the timing of aggradation, we find a correlation between variations in sediment transport with oxygen-isotope records from regions affected by Indian Summer Monsoon. During stronger monsoon phases and post-LGM glacial retreat manifested by increased sediment delivery (moraines and hillslope-derived) to the trunk streams, causing aggradation in the basin; whereas, weakened monsoon phases characterized by reduced sediment-delivery from the hillslope or moraines resulted into incision of the transiently-stored sediments. Sediment cycles in the Kangra Basin are largely synchronous with those documented from other NW Himalayan valleys.

Deriving earthquake history of the Knidos Fault Zone, SW Turkey, using cosmogenic 36Cl surface exposure dating of the fault scarp.

NASA Astrophysics Data System (ADS)

Yildirim, Cengiz; Ersen Aksoy, Murat; Akif Sarikaya, Mehmet; Tuysuz, Okan; Genc, S. Can; Ertekin Doksanalti, Mustafa; Sahin, Sefa; Benedetti, Lucilla; Tesson, Jim; Aster Team

2016-04-01

Formation of bedrock fault scarps in extensional provinces is a result of large and successive earthquakes that ruptured the surface several times. Extraction of seismic history of such faults is critical to understand the recurrence intervals and the magnitude of paleo-earthquakes and to better constrain the regional seismic hazard. Knidos on the Datca Peninsula (SW Turkey) is one of the largest cities of the antique times and sits on a terraced hill slope formed by en-echelon W-SW oriented normal faults. The Datça Peninsula constitutes the southern boundary of the Gulf of Gökova, one of the largest grabens developed on the southernmost part of the Western Anatolian Extensional Province. Our investigation relies on cosmogenic 36Cl surface exposure dating of limestone faults scarps. This method is a powerful tool to reconstruct the seismic history of normal faults (e.g. Schlagenhauf et al 2010, Benedetti et al. 2013). We focus on one of the most prominent fault scarp (hereinafter Mezarlık Fault) of the Knidos fault zone cutting through the antique Knidos city. We collected 128 pieces of tablet size (10x20cm) 3-cm thick samples along the fault dip and opened 4 conventional paleoseismic trenches at the base of the fault scarp. Our 36Cl concentration profile indicates that 3 to 4 seismic events ruptured the Mezarlık Fault since Last Glacial Maximum (LGM). The results from the paleoseismic trenching are also compatible with 36Cl results, indicating 3 or 4 seismic events that disturbed the colluvium deposited at the base of the scarp. Here we will present implications for the seismic history and the derived slip-rate of the Mezarlık Fault based on those results. This project is supported by The Scientific and Technological Research Council of Turkey (TUBITAK, Grant number: 113Y436) and it was conducted with the Decision of the Council of Ministers with No. 2013/5387 on the date 30.09.2013 and was done with the permission of Knidos Presidency of excavation in accordance with the scope of Knidos Excavation and Research carried out on behalf of Selcuk University and Ministry of Culture and Tourism.

Considerations for successful cosmogenic 3He dating in accessory phases

NASA Astrophysics Data System (ADS)

Amidon, W. H.; Farley, K. A.; Rood, D. H.

2008-12-01

We have been working to develop cosmogenic 3He dating of phases other than the commonly dated olivine and pyroxene, especially apatite and zircon. Recent work by Dunai et al. underscores that cosmogenic 3He dating is complicated by 3He production via 6Li(n,α) 3H --> 3He. The reacting thermal neutrons can be produced from three distinct sources; nucleogenic processes (3Henuc), muon interactions (3Hemu), and by high-energy "cosmogenic" neutrons (3Hecn). Accurate cosmogenic 3He dating requires determination of the relative fractions of Li-derived and spallation derived 3He. An important complication for the fine-grained phases we are investigating is that both spallation and the 6Li reaction eject high energy particles, with consequences for redistribution of 3He among phases in a rock. Although shielded samples can be used to estimate 3Henuc, they do not conatin the 3Hecn component produced in the near surface. To calculate this component, we propose a procedure in which the bulk rock chemistry, helium closure age, 3He concentration, grain size and Li content of the target mineral are measured in a shielded sample. The average Li content of the adjacent minerals can then be calculated, which in turn allows calculation of the 3Hecn component in surface exposed samples of the same lithology. If identical grain sizes are used in the shielded and surface exposed samples, then "effective" Li can be calculated directly from the shielded sample, and it may not be necessary to measure Li at all. To help validate our theoretical understanding of Li-3He production, and to constrain the geologic contexts in which cosmogenic 3He dating with zircon and apatite is likely to be successful, results are presented from four different field locations. For example, results from ~18 Ky old moraines in the Sierra Nevada show that the combination of low Li contents and high closure ages (>50 My) creates a small 3Hecn component (2%) but a large 3Henuc component (40-70%) for zircon and apatite. In contrast the combination of high Li contents and a young closure age (0.6 My) in rhyolite from the Coso volcanic field leads to a large 3Hecn component (30%) and small 3Henuc component (5%) in zircon. Analysis of samples from a variety of lithologies shows that zircon and apatite tend to be low in Li (1-10 ppm), but are vulnerable to implantation of 3He from adjacent minerals due to their small grain size, especially from minerals like biotite and hornblende. This point is well illustrated by data from both the Sierra Nevada and Coso examples, in which there is a strong correlation between grain size and 3He concentration for zircons due to implantation. In contrast, very large zircons (150>125 um width) obtained from shielded samples of the Shoshone Falls rhyolite (SW Idaho) do not contain a significant implanted component. Thus, successful 3He dating of accessory phases requires low Li content (<10 ppm) in the target mineral and either 1) low Li in adjacent minerals, or 2) the use of large grain sizes (>100 um). In high-Li cases, the fraction of 3Henuc is minimized in samples with young helium closure ages or longer duration of exposure. However because the 3Hecn/3Hespall ratio is fixed for a given Li content, longer exposure will not reduce the fraction of 3Hecn.

Evidence for two surface ruptures in the past 500 years on the San Andreas fault at Frazier Mountain, California

USGS Publications Warehouse

Lindvall, S.C.; Rockwell, T.K.; Dawson, T.E.; Helms, J.G.; Bowman, K.W.

2002-01-01

We conducted paleoseismic studies in a closed depression along the San Andreas fault on the north flank of Frazier Mountain near Frazier Park, California. We recognized two earthquake ruptures in our trench exposure and interpreted the most recent rupture, event 1, to represent the historical 1857 earthquake. We also exposed evidence of an earlier surface rupture, event 2, along an older group of faults that did not rerupture during event 1. Radiocarbon dating of the stratigraphy above and below the earlier event constrains its probable age to between A.D. 1460 and 1600. Because we documented continuous, unfaulted stratigraphy between the earlier event horizon and the youngest event horizon in the portion of the fault zone exposed, we infer event 2 to be the penultimate event. We observed no direct evidence of an 1812 earthquake in our exposures. However, we cannot preclude the presence of this event at our site due to limited age control in the upper part of the section and the possibility of other fault strands beyond the limits of our exposures. Based on overlapping age ranges, event 2 at Frazier Mountain may correlate with event B at the Bidart fan site in the Carrizo Plain to the northwest and events V and W4 at Pallett Creek and Wrightwood, respectively, to the southeast. If the events recognized at these multiple sites resulted from the same surface rupture, then it appears that the San Andreas fault has repeatedly failed in large ruptures similar in extent to 1857.

Efficacy of antimicrobial 405 nm blue-light for inactivation of airborne bacteria

NASA Astrophysics Data System (ADS)

Dougall, Laura R.; Anderson, John G.; Timoshkin, Igor V.; MacGregor, Scott J.; Maclean, Michelle

2018-02-01

Airborne transmission of infectious organisms is a considerable concern within the healthcare environment. A number of novel methods for `whole room' decontamination, including antimicrobial 405 nm blue light, are being developed. To date, research has focused on its effects against surface-deposited contamination; however, it is important to also establish its efficacy against airborne bacteria. This study demonstrates evidence of the dose-response kinetics of airborne bacterial contamination when exposed to 405 nm light and compares bacterial susceptibility when exposed in three different media: air, liquid and surfaces. Bacterial aerosols of Staphylococcus epidermidis, generated using a 6-Jet Collison nebulizer, were introduced into an aerosol suspension chamber. Aerosolized bacteria were exposed to increasing doses of 405 nm light, and air samples were extracted from the chamber using a BioSampler liquid impinger, with viability analysed using pour-plate culture. Results have demonstrated successful aerosol inactivation, with a 99.1% reduction achieved with a 30 minute exposure to high irradiance (22 mWcm-2) 405 nm light (P=0.001). Comparison to liquid and surface exposures proved bacteria to be 3-4 times more susceptible to 405 nm light inactivation when in aerosol form. Overall, results have provided fundamental evidence of the susceptibility of bacterial aerosols to antimicrobial 405 nm light treatment, which offers benefits in terms of increased safety for human exposure, and eradication of microbes regardless of antibiotic resistance. Such benefits provide advantages for a number of applications including `whole room' environmental decontamination, in which reducing levels of airborne bacteria should reduce the number of infections arising from airborne contamination.

Hydroxyapatite formation on titania-based materials in a solution mimicking body fluid: Effects of manganese and iron addition in anatase.

PubMed

Shin, Euisup; Kim, Ill Yong; Cho, Sung Baek; Ohtsuki, Chikara

2015-03-01

Hydroxyapatite formation on the surfaces of implanted materials plays an important role in osteoconduction of bone substitutes in bone tissues. Titania hydrogels are known to instigate hydroxyapatite formation in a solution mimicking human blood plasma. To date, the relationship between the surface characteristics of titania and hydroxyapatite formation on its surface remains unclear. In this study, titania powders with varying surface characteristics were prepared by addition of manganese or iron to examine hydroxyapatite formation in a type of simulated body fluid (Kokubo solution). Hydroxyapatite formation was monitored by observation of deposited particles with scale-like morphology on the prepared titania powders. The effect of the titania surface characteristics, i.e., crystal structure, zeta potential, hydroxy group content, and specific surface area, on hydroxyapatite formation was examined. Hydroxyapatite formation was observed on the surface of titania powders that were primarily anatase, and featured a negative zeta potential and low specific surface areas irrespective of the hydroxy group content. High specific surface areas inhibited the formation of hydroxyapatite because calcium and phosphate ions were mostly consumed by adsorption on the titania surface. Thus, these surface characteristics of titania determine its osteoconductivity following exposure to body fluid. Copyright © 2014 Elsevier B.V. All rights reserved.

Simulating LGM retreat of the Uummannaq Ice Stream and Rinks Isbrae, Western Greenland using a 1-D ice-stream model constrained by a suite of marine and terrestrial data

NASA Astrophysics Data System (ADS)

Jamieson, Stewart; Roberts, Dave; Rea, Brice; Lane, Timothy; Vieli, Andreas; Cofaigh, Colm Ó.

2014-05-01

We aim to understand what controlled the retreat pattern of the Uummannaq Ice Stream (UIS) during the last deglaciation. Evidence for the pattern of retreat is found in both the marine and terrestrial realms, but because the evidence is temporally and spatially discontinuous, it is challenging to coherently reconstruct both grounding-line retreat and ice-surface thinning such that they are in agreement. Marine stratigraphic and geophysical evidence indicates that the ice stream was grounded close to the continental shelf edge at the Last Glacial Maximum, and retreated rapidly and nonlinearly after 14.8 ka. Cosmogenic nuclide exposure dating on Ubekendt Island at the convergence zone of multiple feeder ice streams show that the ice surface thinned progressively and that the island became ice-free by ca. 12.4 ka. The ice stream then collapsed over the next 1-1.6 kyrs and the ice stream separated into a series of distinct inland arms. In the northernmost Rinks system, there is a 'staircase' of evidence showing ice surface thinning over time, but it is unclear where the grounding line was located during this phase of thinning. Furthermore, it is currently unclear what controlled the nonlinear retreat pattern identified in the Uummannaq system. We develop a numerical model of ice-stream retreat using the marine geophysical data and measurements of sediment strength on the continental shelf to control the boundary conditions. The model has the capability to dynamically and robustly simulate grounding line-retreat behaviour over millennial timescales. We simulate the retreat of the UIS grounding line into the northernmost Rinks system in response to enhanced ocean warming, rising sea level and warming climate. We compare the simulated dynamic behaviour of the UIS against the geomorphological and cosmogenic exposure evidence for ice surface thinning onshore and against dated marine grounding line positions. Our model results enable us to match grounding-line positions in the marine trough to distinct onshore ice-surface heights, and therefore provide a 2-dimensional reconstruction of the geometry of the UIS as it retreated after the LGM. We find that the nonlinearity in retreat rate is conditioned by the locations of vertical and lateral constrictions in the Uummannaq/Rink trough which provide temporary pinning points for the grounding line. When the grounding line retreats rapidly between pinning points, the ice surface thins rapidly inland. When the grounding line is pinned, thinning of the ice surface becomes much slower in locations corresponding to the deposition of moraines. We suggest that the slowdowns in retreat identified in the marine domain are therefore reflected by the generation of moraines in the terrestrial domain. Finally, we generate hypotheses about the timing of marine grounding-line retreat based upon the published terrestrial cosmogenic exposure ages.

Issues Related to Cleaning Complex Geometry Surfaces with ODC-Free Solvents

NASA Technical Reports Server (NTRS)

Bradford, Blake F.; Wurth, Laura A.; Nayate, Pramod D.; McCool, Alex (Technical Monitor)

2001-01-01

Implementing ozone depleting chemicals (ODC)-free solvents into full-scale reusable solid rocket motor cleaning operations has presented problems due to the low vapor pressures of the solvents. Because of slow evaporation, solvent retention is a problem on porous substrates or on surfaces with irregular geometry, such as threaded boltholes, leak check ports, and nozzle backfill joints. The new solvents are being evaluated to replace 1,1,1-trichloroethane, which readily evaporates from these surfaces. Selection of the solvents to be evaluated on full-scale hardware was made based on results of subscale tests performed with flat surface coupons, which did not manifest the problem. Test efforts have been undertaken to address concerns with the slow-evaporating solvents. These concerns include effects on materials due to long-term exposure to solvent, potential migration from bolthole threads to seal surfaces, and effects on bolt loading due to solvent retention in threads. Tests performed to date have verified that retained solvent does not affect materials or hardware performance. Process modifications have also been developed to assist drying, and these can be implemented if additional drying becomes necessary.

Climatic and topographic controls on the style and timing of Late Quaternary glaciation throughout Tibet and the Himalaya defined by 10Be cosmogenic radionuclide surface exposure dating

USGS Publications Warehouse

Owen, L.A.; Finkel, R.C.; Barnard, P.L.; Haizhou, Ma; Asahi, K.; Caffee, M.W.; Derbyshire, E.

2005-01-01

Temporal and spatial changes in glacier cover throughout the Late Quaternary in Tibet and the bordering mountains are poorly defined because of the inaccessibility and vastness of the region, and the lack of numerical dating. To help reconstruct the timing and extent of glaciation throughout Tibet and the bordering mountains, we use geomorphic mapping and 10Be cosmogenic radionuclide (CRN) surface dating in study areas in southeastern (Gonga Shan), southern (Karola Pass) and central (Western Nyainqentanggulha Shan and Tanggula Shan) Tibet, and we compare these with recently determined numerical chronologies in other parts of the plateau and its borderlands. Each of the study regions receives its precipitation mainly during the south Asian summer monsoon when it falls as snow at high altitudes. Gonga Shan receives the most precipitation (>2000 mm a-1) while, near the margins of monsoon influence, the Karola Pass receives moderate amounts of precipitation (500-600 mm a-1) and, in the interior of the plateau, little precipitation falls on the western Nyainqentanggulha Shan (???300 mm a -1) and the Tanggula Shan (400-700 mm a-1). The higher precipitation values for the Tanggula Shan are due to strong orographic effects. In each region, at least three sets of moraines and associated landforms are preserved, providing evidence for multiple glaciations. The 10Be CRN surface exposure dating shows that the formation of moraines in Gonga Shan occurred during the early-mid Holocene, Neoglacial and Little Ice Age, on the Karola Pass during the Lateglacial, Early Holocene and Neoglacial, in the Nyainqentanggulha Shan date during the early part of the last glacial cycle, global Last Glacial Maximum and Lateglacial, and on the Tanggula Shan during the penultimate glacial cycle and the early part of the last glacial cycle. The oldest moraine succession in each of these regions varies from the early Holocene (Gonga Shan), Lateglacial (Karola Pass), early Last Glacial (western Nyainqentanggulha Shan), and penultimate glacial cycle (Tanggula Shan). We believe that the regional patterns and timing of glaciation reflect temporal and spatial variability in the south Asian monsoon and, in particular, in regional precipitation gradients. In zones of greater aridity, the extent of glaciation has become increasingly restricted throughout the Late Quaternary leading to the preservation of old (???100 ka) glacial landforms. In contrast, in regions that are very strongly influenced by the monsoon (???1600 mm a-1), the preservation potential of pre-Lateglacial moraine successions is generally extremely poor. This is possibly because Lateglacial and Holocene glacial advances may have been more extensive than early glaciations and hence may have destroyed any landform or sedimentary evidence of earlier glaciations. Furthermore, the intense denudation, mainly by fluvial and mass movement processes, which characterize these wetter environments, results in rapid erosion and re-sedimentation of glacial and associated landforms, which also contributes to their poor preservation potential. ?? 2004 Elsevier Ltd. All rights reserved.

Design and dosimetric characteristics of a new endocavitary contact radiotherapy system using an electronic brachytherapy source.

PubMed

Richardson, Susan; Garcia-Ramirez, Jose; Lu, Wei; Myerson, Robert J; Parikh, Parag

2012-11-01

To present design aspects and acceptance tests performed for clinical implementation of electronic brachytherapy treatment of early stage rectal adenocarcinoma. A dosimetric comparison is made between the historically used Philips RT-50 unit and the newly developed Axxent(®) Model S700 electronic brachytherapy source manufactured by Xoft (iCad, Inc.). Two proctoscope cones were manufactured by ElectroSurgical Instruments (ESI). Two custom surface applicators were manufactured by Xoft and were designed to fit and interlock with the proctoscope cones from ESI. Dose rates, half value layers (HVL), and percentage depth dose (PDD) measurements were made with the Xoft system and compared to historical RT-50 data. A description of the patient treatment approach and exposure rates during the procedure is also provided. The electronic brachytherapy system has a lower surface dose rate than the RT-50. The dose rate to water on the surface from the Xoft system is approximately 2.1 Gy∕min while the RT-50 is 10-12 Gy∕min. However, treatment times with Xoft are still reasonable. The HVLs and PDDs between the two systems were comparable resulting in similar doses to the target and to regions beyond the target. The exposure rate levels around a patient treatment were acceptable. The standard uncertainty in the dose rate to water on the surface is approximately ±5.2%. The Philips RT-50 unit is an out-of-date radiotherapy machine that is no longer manufactured with limited replacement parts. The use of a custom-designed proctoscope and Xoft surface applicators allows delivery of a well-established treatment with the ease of a modern radiotherapy device. While the dose rate is lower with the use of Xoft, the treatment times are still reasonable. Additionally, personnel may stand farther away from the Xoft radiation source, thus potentially reducing radiation exposure to the operator and other personnel.

Predicting Adolescent Dating Violence Perpetration: Role of Exposure to Intimate Partner Violence and Parenting Practices.

PubMed

Latzman, Natasha E; Vivolo-Kantor, Alana M; Holditch Niolon, Phyllis; Ghazarian, Sharon R

2015-09-01

Exposure to adult intimate partner violence (IPV) places youth at risk for a range of outcomes, including perpetration of adolescent dating violence (ADV). However, there is variability in the effect of IPV exposure, as many youth who are exposed to IPV do not go on to exhibit problems. Thus, research is needed to examine contextual factors, such as parenting practices, to more fully explain heterogeneity in outcomes and better predict ADV perpetration. The current research draws from a multisite study to investigate the predictive power of IPV exposure and parenting practices on subsequent ADV perpetration. Participants included 417 adolescents (48.7% female) drawn from middle schools in high-risk, urban communities. IPV exposure, two types of parenting practices (positive parenting/involvement and parental knowledge of their child's dating), and five types of ADV perpetration (threatening behaviors, verbal/emotional abuse, relational abuse, physical abuse, and sexual abuse) were assessed at baseline (2012) and approximately 5 months later (2013) via adolescent report. Analyses (conducted in 2015) used a structural equation modeling approach. Structural models indicated that IPV exposure was positively related only to relational abuse at follow-up. Further, adolescents who reported parents having less knowledge of dating partners were more likely to report perpetrating two types of ADV (physical and verbal/emotional abuse) at follow-up. Analyses did not demonstrate any significant interaction effects. Results fill a critical gap in understanding of important targets to prevent ADV in middle school and highlight the important role that parents may play in ADV prevention. Published by Elsevier Inc.

Active transpressional tectonics in the Andean forearc of southern Peru quantified by 10Be surface exposure dating of an active fault scarp

NASA Astrophysics Data System (ADS)

Benavente, Carlos; Zerathe, Swann; Audin, Laurence; Hall, Sarah R.; Robert, Xavier; Delgado, Fabrizio; Carcaillet, Julien; Team, Aster

2017-09-01

Our understanding of the style and rate of Quaternary tectonic deformation in the forearc of the Central Andes is hampered by a lack of field observations and constraints on neotectonic structures. Here we present a detailed analysis of the Purgatorio fault, a recently recognized active fault located in the forearc of southern Peru. Based on field and remote sensing analysis (Pléiades DEM), we define the Purgatorio fault as a subvertical structure trending NW-SE to W-E along its 60 km length, connecting, on its eastern end, to the crustal Incapuquio Fault System. The Purgatorio fault accommodates right-lateral transpressional deformation, as shown by the numerous lateral and vertical plurimetric offsets recorded along strike. In particular, scarp with a 5 m cumulative throw is preserved and displays cobbles that are cut and covered by slickensides. Cosmogenic radionuclide exposure dating (10Be) of quartzite cobbles along the vertical fault scarp yields young exposure ages that can be bracketed between 0 to 6 ka, depending on the inheritance model that is applied. Our preferred scenario, which takes in account our geomorphic observations, implies at least two distinct rupture events, each associated with 3 and 2 m of vertical offset. These two events plausibly occurred during the last thousand years. Nevertheless, an interpretation invoking more tectonic events along the fault cannot be ruled out. This work affirms crustal deformation along active faults in the Andean forearc of southern Peru during the last thousand years.

Offset of Tertiary arcs on the Alaska Peninsula: A section in Geological Survey research, fiscal year 1981

USGS Publications Warehouse

,

1984-01-01

Geologic mapping and potassium-argon dating by R. L. Detterman, F. H. Wilson, J. E. Case, and Nora Shew in the Ugashik and western part of the Karluk quadrangles have shown that the Eocene and Oligocene volcanic arc continues into these quadrangles from the south in the Chignik and Sutwik Island quadrangles. Surface exposures of the arc extend northward to approximately 57°30'N., or midway through the Ugashik quadrangle, but none are observed north of that point. Subsurface drill-hole data (Brockway and others, 1975) indicate continuation of the arc, possibly offset to the northwest of the northernmost known surface exposures.In the extreme northern part of the Ugashik and Karluk quadrangles, volcanic rocks again become important. These volcanic rocks are as yet undated; however, they may be related to the Katmai late Tertiary volcanic centers.Like the early Tertiary volcanic arc, the present-day Aleutian arc is also offset to the northwest in the northern part of the Ugashik and Karluk quadrangles. No major offset of the Mesozoic rocks is indicated through the offset zone; this fact suggests a change in the Tertiary tectonic regime in the area of the offset.

The Diesel Exhaust in Miners Study: V. Evaluation of the Exposure Assessment Methods

PubMed Central

Stewart, Patricia A.; Vermeulen, Roel; Coble, Joseph B.; Blair, Aaron; Schleiff, Patricia; Lubin, Jay H.; Attfield, Mike; Silverman, Debra T.

2012-01-01

Exposure to respirable elemental carbon (REC), a component of diesel exhaust (DE), was assessed for an epidemiologic study investigating the association between DE and mortality, particularly from lung cancer, among miners at eight mining facilities from the date of dieselization (1947–1967) through 1997. To provide insight into the quality of the estimates for use in the epidemiologic analyses, several approaches were taken to evaluate the exposure assessment process and the quality of the estimates. An analysis of variance was conducted to evaluate the variability of 1998–2001 REC measurements within and between exposure groups of underground jobs. Estimates for the surface exposure groups were evaluated to determine if the arithmetic means (AMs) of the REC measurements increased with increased proximity to, or use of, diesel-powered equipment, which was the basis on which the surface groups were formed. Estimates of carbon monoxide (CO) (another component of DE) air concentrations in 1976–1977, derived from models developed to predict estimated historical exposures, were compared to 1976–1977 CO measurement data that had not been used in the model development. Alternative sets of estimates were developed to investigate the robustness of various model assumptions. These estimates were based on prediction models using: (i) REC medians rather AMs, (ii) a different CO:REC proportionality than a 1:1 relation, and (iii) 5-year averages of historical CO measurements rather than modeled historical CO measurements and DE-related determinants. The analysis of variance found that in three of the facilities, most of the between-group variability in the underground measurements was explained by the use of job titles. There was relatively little between-group variability in the other facilities. The estimated REC AMs for the surface exposure groups rose overall from 1 to 5 μg m−3 as proximity to, and use of, diesel equipment increased. The alternative estimates overall were highly correlated (∼0.9) with the primary set of estimates. The median of the relative differences between the 1976–1977 CO measurement means and the 1976–1977 estimates for six facilities was 29%. Comparison of estimated CO air concentrations from the facility-specific prediction models with historical CO measurement data found an overall agreement similar to that observed in other epidemiologic studies. Other evaluations of components of the exposure assessment process found moderate to excellent agreement. Thus, the overall evidence suggests that the estimates were likely accurate representations of historical personal exposure levels to DE and are useful for epidemiologic analyses. PMID:22383674

Maternal Residential Exposure to Agricultural Pesticides and ...

EPA Pesticide Factsheets

Birth defects are responsible for a large proportion of disability and infant mortality. Exposure to a variety of pesticides have been linked to increased risk of birth defects. We conducted a case-control study to estimate the associations between a residence-based metric of agricultural pesticide exposure and birth defects. We linked singleton live birth records for 2003-2005 from the North Carolina (NC) State Center for Health Statistics to data from the NC Birth Defects Monitoring Program. Included women had residence at delivery inside NC and infants with gestational ages from 20-44 weeks (n=304,906). Pesticide exposure was assigned using a previously constructed metric, estimating total chemical exposure (pounds of active ingredient) based on crops within 500 meters of maternal residence, specific dates of pregnancy, and chemical application dates based on the planting/harvesting dates of each crop. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) for four categories of exposure (90th percentiles) compared to unexposed. Models were adjusted for maternal race, age at delivery, education, marital status, and smoking status. We observed elevated ORs for congenital heart defects and certain structural defects affecting the gastrointestinal, genitourinary and musculoskeletal systems (e.g., OR (95% CI) (highest exposure vs. unexposed) for tracheal esophageal fistula/esophageal atresia = 1.98 (0.69, 5.66), and OR for atr

Late Quaternary alluvial fans of Emli Valley in the Ecemiş Fault Zone, south central Turkey: Insights from cosmogenic nuclides

NASA Astrophysics Data System (ADS)

Akif Sarıkaya, M.; Yıldırım, Cengiz; Çiner, Attila

2015-01-01

Alluvial fans within the paraglacial Ecemiş River drainages on the Aladağlar Mountains in south central Turkey were studied using geomorphological, sedimentological, and chlorine-36 terrestrial cosmogenic nuclide (TCN) surface exposure dating methods to examine the timing of alluvial fan abandonment/incision, and to understand the role of climatic and tectonic processes in the region. These alluvial fan complexes are among the best-preserved succession of alluvial fans in Turkey and they were offset by the major strike-slip Ecemiş Fault of the Central Anatolian Fault Zone. The alluvial fans are mostly composed of well-lithified limestone cobbles (5 to 25 cm in size), and comprise crudely stratified thick beds with a total thickness reaching up to about 80 m. TCN surface exposure dating indicates that the oldest alluvial fan surface (Yalak Fan) was likely formed and subsequently abandoned latest by 136.0 ± 23.4 ka ago, largely on the transition of the Penultimate Glaciation (Marine Isotope Stage 6, MIS 6) to the Last Interglacial (MIS 5) (i.e. Termination II). The second set of alluvial fan (Emli Fan) was possibly developed during the Last Interglacial (MIS 5), and incised twice by between roughly 97.0 ± 13.8 and 81.2 ± 13.2 ka ago. A younger alluvial fan deposit placed on relatively older erosional terraces of the Emli Fan suggests that it may have been produced during the Last Glacial Cycle (MIS 2). These events are similar to findings from other fluvial and lacustrine deposits throughout central Anatolia. The incision times of the Ecemiş alluvial fan surfaces largely coincide with major climatic shifts from the cooler glacial periods to warmer interglacial/interstadial conditions. This indicates that alluvial fans were produced by outwash sediments of paleoglaciers during cooler conditions, and, later, when glaciers started to retreat due to a major warming event, the excess water released from the glaciers incised the pre-existing fan surfaces. An alluvial fan in the study area was also cut by the Ecemiş Fault, highlighting the influence of tectonics on fan development. It was offset vertically 35 ± 3 m since at least 97.0 ± 13.8 ka, which suggests a 0.36 ± 0.06 mm a- 1 vertical slip-rate of the fault.

About the Exposure Factors Program

EPA Science Inventory

Since the first version of the EFH was released in 1989, the need for the most up-to-date and accurate data on exposure factors used in assessing exposure to contaminants in the environment is of high priority to exposure assessors throughout the U.S. The compl...

Breast Implant-Associated Anaplastic Large Cell Lymphoma in Australia and New Zealand: High-Surface-Area Textured Implants Are Associated with Increased Risk.

PubMed

Loch-Wilkinson, Anna; Beath, Kenneth J; Knight, Robert John William; Wessels, William Louis Fick; Magnusson, Mark; Papadopoulos, Tim; Connell, Tony; Lofts, Julian; Locke, Michelle; Hopper, Ingrid; Cooter, Rodney; Vickery, Karen; Joshi, Preeti Avinash; Prince, H Miles; Deva, Anand K

2017-10-01

The association between breast implants and breast implant-associated anaplastic large cell lymphoma (ALCL) has been confirmed. Implant-related risk has been difficult to estimate to date due to incomplete datasets. All cases in Australia and New Zealand were identified and analyzed. Textured implants reported in this group were subjected to surface area analysis. Sales data from three leading breast implant manufacturers (i.e., Mentor, Allergan, and Silimed) dating back to 1999 were secured to estimate implant-specific risk. Fifty-five cases of breast implant-associated ALCL were diagnosed in Australia and New Zealand between 2007 and 2016. The mean age of patients was 47.1 years and the mean time of implant exposure was 7.46 years. There were four deaths in the series related to mass and/or metastatic presentation. All patients were exposed to textured implants. Surface area analysis confirmed that higher surface area was associated with 64 of the 75 implants used (85.3 percent). Biocell salt loss textured (Allergan, Inamed, and McGhan) implants accounted for 58.7 percent of the implants used in this series. Comparative analysis showed the risk of developing breast implant-associated ALCL to be 14.11 times higher with Biocell textured implants and 10.84 higher with polyurethane (Silimed) textured implants compared with Siltex textured implants. This study has calculated implant-specific risk of breast implant-associated ALCL. Higher-surface-area textured implants have been shown to significantly increase the risk of breast implant-associated ALCL in Australia and New Zealand. The authors present a unifying hypothesis to explain these observations.

Maladaptive schemas as mediators of the relationship between previous victimizations in the family and dating violence victimization in adolescents.

PubMed

Calvete, Esther; Gámez-Guadix, Manuel; Fernández-Gonzalez, Liria; Orue, Izaskun; Borrajo, Erika

2018-07-01

This study examined whether exposure to family violence, both in the form of direct victimization and witnessing violence, predicted dating violence victimization in adolescents through maladaptive schemas. A sample of 933 adolescents (445 boys and 488 girls), aged between 13 and 18 (M = 15.10), participated in a three-year longitudinal study. They completed measures of exposure to family violence, maladaptive schemas of disconnection/rejection, and dating violence victimization. The findings indicate that witnessing family violence predicts the increase of dating violence victimization over time, through the mediation of maladaptive schemas in girls, but not in boys. Direct victimization in the family predicts dating violence victimization directly, without the mediation of schemas. In addition, maladaptive schemas contribute to the perpetuation of dating violence victimization over time. These findings provide new opportunities for preventive interventions, as maladaptive schemas can be modified. Copyright © 2018 Elsevier Ltd. All rights reserved.

Virus occupational exposure in solid waste processing facilities.

PubMed

Carducci, Annalaura; Federigi, Ileana; Verani, Marco

2013-11-01

It is well known that workers involved in the management of solid waste are at risk of exposure to bioaerosol, which is generally studied in relation to bacteria, fungi, and endotoxins. However, to date, there have been no reports on the incidence of work-related infectious diseases. To determine if occupational exposure to viruses occurs upon exposure to waste-related activities, monitoring was carried out in a landfill, a waste recycling plant, an incineration plant, and a waste collection vehicles. Air and surfaces were sampled and analyzed for torque teno virus (TTV), human adenovirus (HAdV), norovirus, rotavirus, and enterovirus using polymerase chain reaction (PCR)-based techniques. Positivity was confirmed by sequencing and quantification with real-time PCR; infectivity was also tested for culturable viruses. Samples were analyzed in parallel for mean total bacterial and fungi counts in both the summer and winter. In total, 30% (12/40) of air and 13.5% (5/37) of surface samples collected in plants were positive for HAdV and TTV. Among the eight HAdV-positive samples, six (75%), revealed in landfill and recycling plant air and in incinerator and waste vehicles surfaces, were able to replicate in cell culture and were subsequently confirmed as infective. The frequency of detection of virus-positive samples was similar in both seasons, but with evident differences in the type of virus detected: TTV and HAdV were more frequently detected in the summer and winter, respectively. The area of highest viral contamination was the paper selection landfill. Fungi and bacterial contamination did not correlate with viral presence or concentration. In conclusion, we evidence that working with solid and liquid waste can lead to infectious viruses, included in Group 2 of the European Directive 90/679/CEE pathogens list; thus, further investigation on the sources and routes of contamination is needed in order to assess the occupational risk.

Moon manned missions radiation safety analysis

NASA Astrophysics Data System (ADS)

Tripathi, R. K.; Wilson, J. W.; de Anlelis, G.; Badavi, F. F.

An analysis is performed on the radiation environment found on the surface of the Moon, and applied to different possible lunar base mission scenarios. An optimization technique has been used to obtain mission scenarios minimizing the astronaut radiation exposure and at the same time controlling the effect of shielding, in terms of mass addition and material choice, as a mission cost driver. The optimization process has been realized through minimization of mass along all phases of a mission scenario, in terms of time frame (dates, transfer time length and trajectory, radiation environment), equipment (vehicles, in terms of shape, volume, onboard material choice, size and structure), location (if in space, on the surface, inside or outside a certain habitats), crew characteristics (number, gender, age, tasks) and performance required (spacecraft and habitat volumes), radiation exposure annual and career limit constraint (from NCRP 132), and implementation of the ALARA principle (shelter from the occurrence of Solar Particle Events). On the lunar surface the most important contribution to radiation exposure is given by background Galactic Cosmic Rays (GCR) particles, mostly protons, alpha particles, and some heavy ions, and by locally induced particles, mostly neutrons, created by the interaction between GCR and surface material and emerging from below the surface due to backscattering processes. In this environment manned habitats are to host future crews involved in the construction and/or in the utilization of moon based infrastructure. Three different kinds of lunar missions are considered in the analysis, Moon Base Construction Phase, during which astronauts are on the surface just to build an outpost for future resident crews, Moon Base Outpost Phase, during which astronaut crews are resident but continuing exploration and installation activities, and Moon Base Routine Phase, with long-term shifting resident crews. In each scenario various kinds of habitats, from very simple shelters to more complex bases, are considered in full detail (e.g., shape, thickness, materials, etc) with considerations of various shielding strategies. In this first analysis all the shape considered are cylindrical or composed of combination of cylinders. Moreover, a radiation safety analysis of more future possible habitats like lava tubes has been also performed.

Timing of the last glaciation and subsequent deglaciation in the Ruby Mountains, Great Basin, USA

NASA Astrophysics Data System (ADS)

Laabs, Benjamin J. C.; Munroe, Jeffrey S.; Best, Laura C.; Caffee, Marc W.

2013-01-01

The timing of the last Pleistocene glaciation in western North America is becoming increasingly well understood, largely due to improved methods of obtaining numerical ages of glacial deposits and landforms. Among these, cosmogenic radionuclide surface-exposure dating has been widely applied to moraines of mountain glaciers, providing the framework for understanding terrestrial climate change during and since the last glaciation in western North America. During the Late Pleistocene, the Great Basin of the western United States hosted numerous mountain glaciers, the deposits of which can provide valuable records of past climate changes if their ages can be precisely determined. In this study, twenty-nine cosmogenic radionuclide 10Be surface-exposure ages from a suite of moraines in Seitz Canyon, western Ruby Mountains, limit the timing of the last glacial episode in the interior Great Basin, known as the Angel Lake Glaciation. Results indicate that deposition of a terminal moraine and two recessional moraines began just prior to ˜20.5 ka and continued until ˜20.0 ka. Retreat from the next younger recessional moraine began at ˜17.2 ka, and final deglaciation began at ˜14.8 ka. These ages are broadly consistent with cosmogenic surface-exposure ages from the eastern Sierra Nevada and the western Wasatch Mountains, in the western and eastern extremes of the Great Basin respectively. Furthermore, these ages suggest that the valley glacier in Seitz Canyon was at or near its maximum extent before and during the hydrologic maxima of Pleistocene lakes in the Great Basin, supporting previous suggestions that a cool and wet climate persisted in this region during the early part of the last glacial-interglacial transition.

Association between exposure to ambient air pollution before conception date and likelihood of giving birth to girls in Guangzhou, China

NASA Astrophysics Data System (ADS)

Lin, Hualiang; Liang, Zhijiang; Liu, Tao; Di, Qian; Qian, Zhengmin; Zeng, Weilin; Xiao, Jianpeng; Li, Xing; Guo, Lingchuan; Ma, Wenjun; Zhao, Qingguo

2015-12-01

A few studies have linked ambient air pollution with sex ratio at birth. Most of these studies examined the long-term effects using spatial or temporal comparison approaches. This study aimed to investigate whether parental exposure to air pollution before conception date could affect the likelihood of the offspring being male or female. We used the information collected in a major maternal hospital in Guangzhou, China. The parental exposure to air pollution was assessed using the air pollution concentration before the conception date. Logistic regression models were used to assess the association between air pollution exposure and birth sex with adjustment for potential confounding factors, such as maternal age, parental education levels, long-term trend, season, and weather condition (mean temperature and relative humidity). The analysis revealed that higher air pollution was associated with higher probability of female newborns, with the effective exposure around one week prior to conception date. In the one-pollutant models, PM10, SO2 and NO2 had significant effects. For example, the excess risk was 0.61% (95% confidence interval (95% CI): 0.36%, 0.86%) for a 10 ug/m3 increase in lag 2 day's PM10, 0.42% (95% CI: 0.21%, 0.64%) for lag 3 day's SO2 and 0.97% (95% CI: 0.44%, 1.50%) for lag 3 day's NO2; and in two-pollutant models, PM10 remained statistically significant. These results suggest that parental exposure to ambient air pollution a few days prior to conception might be a contributing factor to higher probability of giving birth to female offspring in Guangzhou.

Live 129I-129Xe dating

NASA Technical Reports Server (NTRS)

Marti, K.

1986-01-01

A technique of cosmic ray exposure age dating using cosmic ray produced I-129 and Xe-129 components is discussed. The live I-129 - Xe-129 method provides an ideal monitor for cosmic ray flux variations on the 10(7)y - 10(8)y time-scale. It is based on low-energy neutron reactions on Te, and these data, when coupled to those from other methods, may facilitate the detection of complex exposure histories.

United States Air Force School of Aerospace Medicine Laser Injury Guidebook

DTIC Science & Technology

2012-04-01

unusual light sources? Have you seen this light(s) before? 2. Date, location, and circumstances a. Date and time (local & Zulu using a 24...hour clock) that the exposure occurred. local: DDMMYYYY hh:mm Zulu : DDMMYYYY hh:mm b. Location of exposure (if nonclassified). Describe location...test. Your retina, cornea, and lens appear normal and there is no evidence of injury. Most people , after encountering a laser incident, quite

Planning for the Paleomagnetic Investigations of Returned Samples from Mars

NASA Astrophysics Data System (ADS)

Weiss, B. P.; Beaty, D. W.; McSween, H. Y., Jr.; Czaja, A. D.; Goreva, Y.; Hausrath, E.; Herd, C. D. K.; Humayun, M.; McCubbin, F. M.; McLennan, S. M.; Pratt, L. M.; Sephton, M. A.; Steele, A.; Hays, L. E.; Meyer, M. A.

2016-12-01

The red planet is a magnetic planet. Mars' iron-rich surface is strongly magnetized, likely dating back to the Noachian period when the surface may have been habitable. Paleomagnetic measurements of returned samples could transform our understanding of the Martian dynamo and its connection to climatic and planetary thermal evolution. Because the original orientations of Martian meteorites are unknown, all Mars paleomagnetic studies to date have only been able to measure the paleointensity of the Martian field. Paleomagnetic studies from returned Martian bedrock samples would provide unprecedented geologic context and the first paleodirectional information on Martian fields. The Mars 2020 rover mission seeks to accomplish the first leg by preparing for the potential return of 31 1 cm-diameter cores of Martian rocks. The Returned Sample Science Board (RSSB) has been tasked to advise the Mars 2020 mission in how to best select and preserve samples optimized for paleomagnetic measurements. A recent community-based study (Weiss et al., 2014) produced a ranked list of key paleomagnetism science objectives, which included: 1) Determine the intensity of the Martian dynamo 2) Characterize the dynamo reversal frequency with magnetostratigraphy 3) Constrain the effects of heating and aqueous alteration on the samples 4) Constrain the history of Martian tectonics Guided by these objectives, the RSSB has proposed four key sample quality criteria to the Mars 2020 mission: (a) no exposure to fields >200 mT, (b) no exposure to temperatures >100 °C, (c) no exposure to pressures >0.1 GPa, and (d) acquisition of samples that are absolutely oriented with respect to bedrock with a half-cone uncertainty of <5°. Our measurements of a Mars 2020 prototype drill have found that criteria (a-c) should be met by the drilling process. Furthermore, the core plate strike and dip will be measured to better than 5° for intact drill cores; we are working with the mission to establish ways to determine the core's angular orientation with respect to rotation around the drill hole axis. The next stage of our work is to establish whether and how these sample criteria would be maintained throughout the potential downstream missions that would return the samples to Earth.

The effects of moms and teens for safe dates: a dating abuse prevention program for adolescents exposed to domestic violence.

PubMed

Foshee, Vangie A; Benefield, Thad; Dixon, Kimberly S; Chang, Ling-Yin; Senkomago, Virginia; Ennett, Susan T; Moracco, Kathryn E; Michael Bowling, J

2015-05-01

Adolescents exposed to domestic violence are at high risk for dating abuse. This randomized controlled trial evaluated a dating abuse prevention program designed specifically for this risk group. Moms and Teens for Safe Dates consisted of six mailed booklets of dating abuse prevention information and interactive activities. Mothers who had been victims of domestic violence but no longer lived with the abuser delivered the program to their adolescents who had been exposed to the abuse. Mother and adolescent pairs (N = 409) were recruited through community advertising; the adolescents ranged from 12 to 16 years old and 64 % were female. Mothers and adolescents completed baseline and 6-month follow-up telephone interviews. Booklet completion in the treatment group ranged from 80 % for the first to 62 % for the last booklet. The analyses first tested whether program effects on dating abuse varied by four a priori identified moderators (mother's psychological health, the amount of adolescent exposure to domestic violence, and adolescent sex and race/ethnicity). Main effects of the program were examined when there were no differential program effects. Program effects on psychological and physical victimization and psychological and cyber perpetration were moderated by the amount of adolescent exposure to domestic violence; there were significant favorable program effects for adolescents with higher, but not lower levels of exposure to domestic violence. There were no moderated or main effects on sexual violence victimization and perpetration or cyber victimization. The findings suggest that a dating abuse prevention program designed for adolescents exposed to domestic violence can have important positive effects.

Holocene geologic slip rate for the Banning strand of the southern San Andreas Fault, southern California

USGS Publications Warehouse

Gold, Peter O.; Behr, Whitney M.; Rood, Dylan; Sharp, Warren D.; Rockwell, Thomas; Kendrick, Katherine J.; Salin, Aaron

2015-01-01

Northwest directed slip from the southern San Andreas Fault is transferred to the Mission Creek, Banning, and Garnet Hill fault strands in the northwestern Coachella Valley. How slip is partitioned between these three faults is critical to southern California seismic hazard estimates but is poorly understood. In this paper, we report the first slip rate measured for the Banning fault strand. We constrain the depositional age of an alluvial fan offset 25 ± 5 m from its source by the Banning strand to between 5.1 ± 0.4 ka (95% confidence interval (CI)) and 6.4 + 3.7/−2.1 ka (95% CI) using U-series dating of pedogenic carbonate clast coatings and 10Be cosmogenic nuclide exposure dating of surface clasts. We calculate a Holocene geologic slip rate for the Banning strand of 3.9 + 2.3/−1.6 mm/yr (median, 95% CI) to 4.9 + 1.0/−0.9 mm/yr (median, 95% CI). This rate represents only 25–35% of the total slip accommodated by this section of the southern San Andreas Fault, suggesting a model in which slip is less concentrated on the Banning strand than previously thought. In rejecting the possibility that the Banning strand is the dominant structure, our results highlight an even greater need for slip rate and paleoseismic measurements along faults in the northwestern Coachella Valley in order to test the validity of current earthquake hazard models. In addition, our comparison of ages measured with U-series and 10Be exposure dating demonstrates the importance of using multiple geochronometers when estimating the depositional age of alluvial landforms.

Cosmogenic Surface-Exposure Dating of Boulders on Last-Glacial and Late-Glacial Moraines, Lago Buenos Aires, Argentina: Interpretive Strategies and Paleoclimate Implications

NASA Astrophysics Data System (ADS)

Douglass, D. C.; Singer, B. S.; Kaplan, M. R.; Mickelson, D. M.; Caffee, M.

2005-12-01

The most substantial and least quantifiable source of uncertainty in cosmogenic surface-exposure datasets is the variable exposure histories of boulders from the same landform. The development of precise and accurate chronologies requires distinguishing boulders that best reflect the age of the landform from those which are outliers. We use the Mean Square of Weighted Deviates statistic and cumulative frequency plots to identify groups of samples that have statistically similar ages based on the number of samples and the uncertainty associated with the analyses. This group of samples most likely represents the best estimate of the landform age. We use these tools to interpret 49 surface-exposure ages from six last-glacial and late-glacial moraines at Lago Buenos Aires, Argentina (LBA; 71.0W, 46.5S). Seven of the orty-nine samples are identified as anomalously young, and are interpreted to have been exhumed after moraine deposition. The remaining samples indicate that glacial advances or still-stands of the ice margin occurred at 22.7±0.9, 21.4±1.9, 19.8±1.1, 17.0±0.8, 15.7±0.6, and 14.4±0.9 ka (±2 σ). This maximum ice extent is roughly synchronous with maximum global ice volume and several of the re-advances are contemporaneous with Heinrich events and other Northern Hemisphere cold periods. The late-glacial readvance at ca. 14.4 ka is contemporaneous with the Antarctic Cold Reversal (ACR), and precedes the Younger Dryas Chronozone (YD). No evidence for a Younger Dryas glacial advance has been found in the Lago Buenos Aires basin. This precise glacial chronology indicates there were significant and important differences in climate across southern South America. The timing of maximum ice extent and onset of deglaciation at LBA occur ~4000 years later than in the Chilean Lake District (41S). Fossil pollen from the CLD area indicates cooler conditions between ca. 14.2 and 11.2, and increased silt in a nearby lake core provides indirect evidence for glacial advances at this time. The onset of this late-glacial cool period precedes the YD, but post-dates the ACR. The LBA glacial record is in better accord with the Strait of Magellan (SM; 52S) than with the CLD. There ice reached its maximum around 25 ka, and a significant late-glacial re-advance occurred between ca. 15 and 11.5 ka. Both LBA and the SM have climate records similar to Antarctica, whereas the climate records from the CLD are combinations of Antarctic and Northern Hemisphere signals.

Multiple glacial culminations from the Lateglacial to the late Holocene in central and southern Peru (Invited)

NASA Astrophysics Data System (ADS)

Licciardi, J. M.; Schaefer, J. M.; Rodbell, D. T.; Stansell, N.; Schweinsberg, A.; Finkel, R. C.; Zimmerman, S. R.

2013-12-01

Fluctuations in small tropical mountain glaciers serve as sensitive indicators of variations in past and present-day climate. Most of the world's modern tropical glaciers reside in the Peruvian Andes, where a growing number of well-dated glacial records have recently been developed. As additional records are documented, regional patterns of late Pleistocene to Holocene glacial activity have begun to emerge. Here we present a compilation of new and previously obtained 10Be surface exposure ages from boulders on well-preserved moraine successions in two glaciated Andean ranges: the Cordillera Vilcabamba of southern Peru (13°20'S, 72°32'W) and the Huaguruncho massif (10°32'S, 75°56'W), located in central Peru ~450 km northwest of the Vilcabamba. A high-resolution composite chronology that merges >100 10Be measurements on moraine sequences in five glaciated drainages of the Cordillera Vilcabamba reveals the occurrence of at least five discrete glacial culminations from the Lateglacial to the late Holocene. At the Huaguruncho massif, >20 10Be exposure ages obtained from moraine sequences in a south-facing cirque indicate at least three major glacial stages spanning the Lateglacial to the Little Ice Age. The moraine ages at Huaguruncho are broadly correlative with the Vilcabamba moraine chronologies, with some dated moraine belts exhibiting geomorphic expressions that closely resemble those of their coeval counterparts in the Vilcabamba. A recurring finding in both field areas is a mismatch between basal radiocarbon ages from bog and lake sediments and 10Be exposure ages on outboard moraines, which enclose the depositional basins. These age discrepancies suggest that cosmogenic 10Be production rates scaled to high altitudes in the tropics are substantially lower than previous estimates. While we anticipate that future refinements to scaled isotope production rates may significantly affect correlation of 10Be exposure ages in the high Andes with ages derived from other dating methods, the revised production rates should have a negligible impact on 10Be age comparisons between the Vilcabamba and Huaguruncho moraines, which lie at similar elevations. The correspondence in age between moraine sequences in these two widely separated ranges suggests regional-scale coherency of multiple glacial fluctuations across the central to southern Peruvian Andes from the Lateglacial to the late Holocene, implying spatially uniform climate drivers along this transect.

The Diesel Exhaust in Miners Study: A Cohort Mortality Study With Emphasis on Lung Cancer

PubMed Central

Schleiff, Patricia L.; Lubin, Jay H.; Blair, Aaron; Stewart, Patricia A.; Vermeulen, Roel; Coble, Joseph B.; Silverman, Debra T.

2012-01-01

Background Current information points to an association between diesel exhaust exposure and lung cancer and other mortality outcomes, but uncertainties remain. Methods We undertook a cohort mortality study of 12 315 workers exposed to diesel exhaust at eight US non-metal mining facilities. Historical measurements and surrogate exposure data, along with study industrial hygiene measurements, were used to derive retrospective quantitative estimates of respirable elemental carbon (REC) exposure for each worker. Standardized mortality ratios and internally adjusted Cox proportional hazard models were used to evaluate REC exposure–associated risk. Analyses were both unlagged and lagged to exclude recent exposure such as that occurring in the 15 years directly before the date of death. Results Standardized mortality ratios for lung cancer (1.26, 95% confidence interval [CI] = 1.09 to 1.44), esophageal cancer (1.83, 95% CI = 1.16 to 2.75), and pneumoconiosis (12.20, 95% CI = 6.82 to 20.12) were elevated in the complete cohort compared with state-based mortality rates, but all-cause, bladder cancer, heart disease, and chronic obstructive pulmonary disease mortality were not. Differences in risk by worker location (ever-underground vs surface only) initially obscured a positive diesel exhaust exposure–response relationship with lung cancer in the complete cohort, although it became apparent after adjustment for worker location. The hazard ratios (HRs) for lung cancer mortality increased with increasing 15-year lagged cumulative REC exposure for ever-underground workers with 5 or more years of tenure to a maximum in the 640 to less than 1280 μg/m3-y category compared with the reference category (0 to <20 μg/m3-y; 30 deaths compared with eight deaths of the total of 93; HR = 5.01, 95% CI = 1.97 to 12.76) but declined at higher exposures. Average REC intensity hazard ratios rose to a plateau around 32 μg/m3. Elevated hazard ratios and evidence of exposure–response were also seen for surface workers. The association between diesel exhaust exposure and lung cancer risk remained after inclusion of other work-related potentially confounding exposures in the models and were robust to alternative approaches to exposure derivation. Conclusions The study findings provide further evidence that exposure to diesel exhaust increases risk of mortality from lung cancer and have important public health implications. PMID:22393207

78 FR 56273 - Occupational Exposure to Respirable Crystalline Silica

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-12

... (b) Definitions (c) Permissible Exposure Limit (PEL) (d) Exposure Assessment (e) Regulated Areas and...) Communication of Respirable Crystalline Silica Hazards to Employees (j) Recordkeeping (k) Dates XVII. References... Maryland) well recognized for its macroeconomic modeling--to run its LIFT (Long-term Interindustry...

No surface breaking on the Ecemiş Fault, central Turkey, since Late Pleistocene (~ 64.5 ka); new geomorphic and geochronologic data from cosmogenic dating of offset alluvial fans

NASA Astrophysics Data System (ADS)

Sarıkaya, M. A.; Yıldırım, C.; Çiner, A.

2015-05-01

The Ecemiş Fault Zone (EF) has been recognized as a major left lateral strike-slip fault in the Central Anatolian Fault Zone (CAFZ) of Turkey. However, its Quaternary slip-rate has been challenging to determine due to the difficulty of dating offset markers. Using high-precision offset measurements and 36Cl cosmogenic nuclide dating, we present the first geochronologically determined Late Quaternary slip-rate for the EF. Our study focuses on the excellent exposures of offset alluvial fan surfaces, originating from the Aladağlar, a Late Quaternary glaciated mountain. Analysis of airborne orthophotogrametry and GNSS (Global Navigation Satellite System) surveys indicates 168 ± 2 m left lateral and 31 ± 1 m vertical displacements. In-situ terrestrial cosmogenic 36Cl geochronology obtained from eleven surface boulders provides a minimum abandonment/incision age of 104.2 ± 16.5 ka for the oldest offset alluvial fan surface. Our geomorphic observations together with Self-potential geophysical surveys revealed the presence of an unfaulted alluvial fan terrace, which allows us to constrain the timing of deformation. The abandonment/incision age of this fan is 64.5 ± 5.6 ka based on thirteen 36Cl depth profile samples. Accordingly, we obtained a geologic fault slip-rate of 4.2 ± 1.9 mm a- 1 horizontally and 0.8 ± 0.3 mm a- 1 vertically for the time frame between 104.2 ± 16.5 ka and 64.5 ± 5.6 ka. Our analysis indicates that the EF has not been producing a major surface breaking earthquake on the main strand at least since 64.5 ± 5.6 ka (mid-Late Pleistocene). This could be the result of abandonment of the main strand and accommodation of deformation by other faults within the EF. Nevertheless, a recently occurred (30 September 2011) low magnitude (ML: 4.3) left lateral strike-slip earthquake indicates recent seismic activity of the EF. Comparison of the recent GPS velocity field with the longer slip history along the CAFZ indicates a constant but low strain release without surface breaking and very long large earthquake recurrence intervals.

Changes in the germination process and growth of pea in effect of laser seed irradiation

NASA Astrophysics Data System (ADS)

Podleśna, Anna; Gładyszewska, Bożena; Podleśny, Janusz; Zgrajka, Wojciech

2015-10-01

The aim of this study was to determine the effect of pre-sowing helium-neon (He-Ne) laser irradiation of pea seeds on changes in seed biochemical processes, germination rate, seedling emergence, growth rate, and yield. The first experimental factor was exposure to laser radiation: D0 - no irradiation, D3 - three exposures, D5 - five exposures, and the harvest dates were the second factor. Pre-sowing treatment of pea seeds with He-Ne laser light increased the concentrations of amylolytic enzymes and the content of indole-3-acetic acid (IAA) in pea seeds and seedlings. The exposure of seeds to He-Ne laser light improved the germination rate and uniformity and modified growth stages, which caused acceleration of flowering and ripening of pea plants. Laser light stimulation improved the morphological characteristics of plants by increasing plant height and leaf surface area. Irradiation improved the yield of vegetative and reproductive organs of pea, although the effects varied at the different growth stages. The increase in the seed yield resulted from a higher number of pods and seeds per plant, whereas no significant changes were observed in the number of seeds per pod. Both radiation doses exerted similarly stimulating effects on pea growth, development, and yield.

Predictors of serum chromium levels after stainless steel posterior spinal instrumentation for adolescent idiopathic scoliosis.

PubMed

Rackham, Matthew D; Cundy, Thomas P; Antoniou, Georgia; Freeman, Brian J C; Sutherland, Leanne M; Cundy, Peter J

2010-04-20

Prospective cohort study. To determine the predictors of serum chromium levels after stainless steel posterior spinal instrumentation for adolescent idiopathic scoliosis. Abnormally elevated serum chromium levels have been detected in patients with adolescent idiopathic scoliosis after stainless steel instrumentation. To date, the relationship among serum chromium levels, time of implantation, and implant characteristics (including surface area, rod length, numbers of hooks, screws, and cross connectors) has not been studied. Thirty patients with adolescent idiopathic scoliosis undergoing posterior instrumented spinal arthrodesis using stainless steel implants between 1998 and 2002 were prospectively studied. Serum chromium levels were measured between October 2006 and June 2007. Postoperative radiographs were used to measure rod lengths, number of hooks, screws, cross-connectors, and cables. The surface area of each component and the total surface area for each patient were calculated. Possible associations between serum chromium levels, time of implantation, and implant characteristics were investigated. Implant exposure, whether expressed in the form of total metal implant surface area, rod length, or number of metal interfaces, was found to be positively associated with serum chromium levels. Specifically, chromium levels increased by a multiplicative factor of 1.0060 for every additional square centimeter of total metal implant surface area (P = 0.02). In addition, the chromium level was found to decrease by a multiplicative factor of 0.7766 for every additional year since surgery (P = 0.02). After adjusting for the number of years since surgery, metal implant exposure is positively associated with elevated serum chromium levels in adolescent idiopathic scoliosis patients with stainless steel posterior spinal implants. This is the first study to identify statistically significant positive associations between specific spinal implant characteristics (other than corrosion identified by radiographs) and serum chromium levels.

Candidate materials for advanced fire-resistant photovoltaic modules

NASA Technical Reports Server (NTRS)

Sugimura, R. S.; Otth, D. H.; Ross, R. G., Jr.; Arnett, J. C.; Samuelson, G.

1985-01-01

A cooperative, cost-sharing research effort to develop a technology base required to construct fire-ratable photovoltaic modules has resulted in the identification of several high-temperature, back-surface candidate materials capable of raising the fire-resistance of modules using hydrocarbon encapsulants to Class A and B levels. Advanced experimental module configurations have been developed using back surfaces consisting of Kapton, Tedlar laminates, metal-foils, and fiberglass materials with high-temperature coatings. Test results (October 1984; March 1985; May 1985; and October 1985) indicate that several of these advanced module configurations are capable of achieving Class B fire-resistance levels, while a few configurations can achieve Class A levels. The paper summarizes activities to date, discussing flammability failure mechanisms, time-temperature profiles, and results of Block V environmental exposure tests of a candidate material suitable for both Class B and Class A fire-resistance levels.

10Be exposure dating of Holocene moraines in the Sierra Nevada, California

NASA Astrophysics Data System (ADS)

Hidy, Alan; Zimmerman, Susan; Finkel, Robert; Schaefer, Jeorg; Clark, Douglas

2016-04-01

Constraint on the extent and timing of Holocene glaciations is critical to addressing standing hypotheses that ascribe climatic fluctuations to changes in atmospheric and oceanic circulation patterns, or anthropogenic forcing. In the terrestrial record, such constraint typically relies on chronologies obtained from 10Be exposure dating of moraine deposits. However, the short exposure time of Holocene moraines, particularly those formed during the Little Ice Age (LIA), makes obtaining precise chronologies extremely challenging. To date, only a handful of LIA deposits in two locations (New Zealand and the Swiss Alps) have been successfully dated with 10Be. Here, we report new 10Be exposure ages from LIA and Neoglacial moraines from multiple sites in the Sierra Nevada (Lyell, Maclure, and Palisade glaciers). The Sierran LIA record will be compared to those from New Zealand and the Swiss Alps to test whether LIA deglaciation was globally synchronous. This result would support the contention that the LIA was terminated by anthropogenically-driven warming. Chronology from the neoglacial deposits will be used to test whether the timing of the return to glacial conditions in the Sierras correlates to a southward shift in the Intertropical Convergence Zone, which has been hypothesized to increase El Nino-like conditions in the Pacific Ocean. This record should be ideal for testing this hypothesis since precipitation in the Sierras is highly sensitive to El Nino conditions.

The Effects of the Moms and Teens for Safe Dates Program on Dating Abuse: a Conditional Process Analysis.

PubMed

Foshee, Vangie A; Benefield, Thad; Chen, May S; Reyes, Luz McNaughton; Dixon, Kimberly S; Ennett, Susan T; Moracco, Kathryn E; Bowling, J Michael

2016-04-01

Moms and Teens for Safe Dates (MTSD) is a dating abuse (DA) prevention program for teens exposed to domestic violence. In a randomized controlled trial (RCT), MTSD prevented certain types of DA victimization (psychological and physical) and perpetration (psychological and cyber) among teens with higher, but not lower, exposure to domestic violence. We built on these findings by using moderated mediation analysis to examine whether level of teen exposure to domestic violence conditioned the indirect effects of MTSD on these types of DA through targeted mediators. MTSD consisted of six mailed activity booklets. Mothers who had been former victims of domestic violence delivered the program to their teens. Mother and teen pairs were recruited into the RCT through community advertising and completed baseline and 6-month follow-up interviews (N = 277 pairs). As expected, MTSD had significant favorable effects for teens with higher but not lower exposure to domestic violence on several mediators that guided program content, including teen conflict management skills and mother-perceived severity of DA, self-efficacy for enacting DA prevention efforts, and comfort in communicating with her teen. MTSD had significant main effects on other mediators including teen feeling of family closeness and cohesion and mother-perceived susceptibility of her teen to DA. As expected, all significant indirect effects of MTSD on DA outcomes through mediators were for teens with higher exposure to domestic violence. Findings have implications for developing DA victimization and perpetration prevention programs for teens with high exposure to domestic violence.

Desiccation and Cold Hardening of Date Palm Somatic Embryos Improve Germination.

PubMed

Shareef, Hussein J

2017-01-01

Embryogenic suspension cultures of date palm are ideal for mass propagation of somatic embryos; however, the low percentage of germination of somatic embryos (SE) remains an impediment. This chapter focuses on two important physical factors to improve germination of date palm somatic embryos: the use of partial desiccation (3 h) of somatic embryos and the exposure to low temperature (4 °C for 24 h). High germination percentage (41%) is achieved by desiccation for 3 h. Moreover, adding 0.3 g/L activated charcoal (AC) to the liquid medium further improves somatic embryo number and weight as well as the percentage of germination. Moreover, partial desiccation and low temperature exposure tend to increase proline content. This improved protocol for somatic embryo germination is potentially applicable for commercial micropropagation of date palm.

The Relationship between Violence in the Family of Origin and Dating Violence among College Students

ERIC Educational Resources Information Center

Gover, Angela R.; Kaukinen, Catherine; Fox, Kathleen A.

2008-01-01

Prior research has established that violence in dating relationships is a serious social problem among adolescents and young adults. Exposure to violence during childhood has been linked to dating violence victimization and perpetration. Also known as the intergenerational transmission of violence, the link between violence during childhood and…

Guide to Current Literature on Exposure Factors

EPA Science Inventory

In an effort to keep the Exposure Factors Handbook up-to-date, the National Center for Environmental Assessment (NCEA) conducted a literature search and summarized recent data on exposure factor...

Characterizing the geomorphic setting of precariously balanced rocks using terrestrial laser scanning technology

NASA Astrophysics Data System (ADS)

Haddad, D. E.; Arrowsmith, R.

2009-12-01

Terrestrial laser scanning (TLS) technology is rapidly becoming an effective three-dimensional imaging tool. Precariously balanced rocks are a subset of spheroidally weathered boulders. They are balanced on bedrock pedestals and are formed in upland drainage basins and pediments of exhumed plutons. Precarious rocks are used as negative evidence of earthquake-driven extreme ground motions. Field surveys of PBRs are coupled with cosmogenic radionuclide (CRN) surface exposure dating techniques to determine their exhumation rates. These rates are used in statistical simulations to estimate the magnitudes and recurrences of earthquake-generated extreme ground shaking as a means to physically validate seismic hazard analyses. However, the geomorphic setting of PBRs in the landscape is poorly constrained when interpreting their exhumation rates from CRN surface exposure dates. Are PBRs located on steep or gentle hillslopes? Are they located near drainages or hillslope crests? What geomorphic processes control the spatial distribution of PBRs in a landscape, and where do these processes dominate? Because the fundamental hillslope transport laws are largely controlled by local hillslope gradient and contributing area, the location of a PBR is controlled by the geomorphic agents and their rates acting on it. Our latest efforts involve using a combination of TLS and airborne laser swath mapping (ALSM) to characterize the geomorphic situation of PBRs. We used a Riegl LPM 800i (LPM 321) terrestrial laser scanner to scan a ~1.5 m tall by ~1 m wide precariously balanced rock in the Granite Dells, central Arizona. The PBR was scanned from six positions, and the scans were aligned to a point cloud totaling 3.4M points. We also scanned a ~50 m by ~150 m area covering PBR hillslopes from five scan positions. The resulting 5.5M points were used to create a digital terrain model of precarious rocks and their hillslopes. Our TLS- and ALSM-generated surface models and DEMs provide a unique opportunity to understand the roles of hillslope-scale geomorphic processes in the PBR life cycle. Initial results show that the studied PBRs are located near hillslope crests ~33 m above the nearest drainages and on slopes >17°. No PBRs were found on gentle slopes adjacent to channels, suggesting that hillslope crests are conducive to preserving PBRs. Understanding these landscape morphometrics for precarious rock zones is critical to building our confidence in interpreting PBR exhumation rates from CRN dating techniques, thus improving the evaluation of seismic hazard analyses.

Reducing healthy worker survivor bias by restricting date of hire in a cohort study of Vermont granite workers

PubMed Central

Applebaum, Katie M; Malloy, Elizabeth J; Eisen, Ellen A

2007-01-01

Objective To explore the healthy worker survivor effect (HWSE) in a study of Vermont granite workers by distinguishing “prevalent” from “incident” hires based on date of hire before or after the start of follow‐up. Methods Records of workers between 1950 and 1982 were obtained from a medical surveillance programme. Proportional hazards models were used to model the association between silica exposure and lung cancer mortality, with penalised splines used to smooth the exposure‐response relationship. A sensitivity analysis compared results between the original cohort and subcohorts defined by restricting date of hire to include varying proportions of prevalent hires. Results Restricting to incident hires reduced the 213 cases by 74% and decreased the exposure range. The maximum mortality rate ratio (MRR) was close to twofold in all subcohorts. However, the exposure at which the maximum MRR was achieved decreased from 4.0 to 0.6 mg‐year/m3 as the proportion of prevalent hires decreased from 50% in the original cohort to 0% in the subcohort of incident hires. Conclusion Despite loss in power and restricted exposure range, decreasing the relative proportion of prevalent to incident hires reduced HWSE bias, resulting in stronger evidence for a dose‐response between silica exposure and lung cancer mortality. PMID:17449560

Developmental timing and continuity of exposure to interparental violence and externalizing behavior as prospective predictors of dating violence.

PubMed

Narayan, Angela J; Englund, Michelle M; Egeland, Byron

2013-11-01

This study investigated the prospective pathways of children's exposure to interparental violence (EIPV) in early and middle childhood and externalizing behavior in middle childhood and adolescence as developmental predictors of dating violence perpetration and victimization at ages 23 and 26 years. Participants (N = 168) were drawn from a longitudinal study of low-income families. Path analyses examined whether timing or continuity of EIPV predicted dating violence and whether timing or continuity of externalizing behavior mediated these pathways. Results indicated that EIPV in early childhood directly predicted perpetration and victimization at age 23. There were significant indirect effects from EIPV to dating violence through externalizing behavior in adolescence and life stress at age 23. Independent of EIPV, externalizing behavior in middle childhood also predicted dating violence through externalizing behavior in adolescence and life stress at age 23, but this pathway stemmed from maltreatment. These results highlight that the timing of EIPV and both the timing and the continuity of externalizing behavior are critical risks for the intergenerational transmission of dating violence. The findings support a developmental perspective that negative early experiences and children's externalizing behavior are powerful influences for dating violence in early adulthood.

Developmental Timing and Continuity of Exposure to Interparental Violence and Externalizing Behavior as Prospective Predictors of Dating Violence

PubMed Central

Narayan, Angela J.; Englund, Michelle M.; Egeland, Byron

2014-01-01

This study investigated the prospective pathways of children's exposure to interparental violence (EIPV) in early and middle childhood and externalizing behavior in middle childhood and adolescence as developmental predictors of dating violence perpetration and victimization at ages 23 and 26 years. Participants (N = 168) were drawn from a longitudinal study of low-income families. Path analyses examined whether timing or continuity of EIPV predicted dating violence and whether timing or continuity of externalizing behavior mediated these pathways. Results indicated that EIPV in early childhood directly predicted perpetration and victimization at age 23. There were significant indirect effects from EIPV to dating violence through externalizing behavior in adolescence and life stress at age 23. Independent of EIPV, externalizing behavior in middle childhood also predicted dating violence through externalizing behavior in adolescence and life stress at age 23, but this pathway stemmed from maltreatment. These results highlight that the timing of EIPV and both the timing and continuity of externalizing behavior are critical risks for the intergenerational transmission of dating violence. Findings support a developmental perspective that negative early experiences and children's externalizing behavior are powerful influences for dating violence in early adulthood. PMID:24229543

21 CFR 660.41 - Processing.

Code of Federal Regulations, 2011 CFR

2011-04-01

... STANDARDS FOR DIAGNOSTIC SUBSTANCES FOR LABORATORY TESTS Hepatitis B Surface Antigen § 660.41 Processing. (a... that will reduce the risk of transmitting type B viral hepatitis. (b) Ancillary reagents and materials... its dating period. (d) Date of manufacture. The date of manufacture of Hepatitis B Surface Antigen...

21 CFR 660.41 - Processing.

Code of Federal Regulations, 2014 CFR

2014-04-01

... STANDARDS FOR DIAGNOSTIC SUBSTANCES FOR LABORATORY TESTS Hepatitis B Surface Antigen § 660.41 Processing. (a... that will reduce the risk of transmitting type B viral hepatitis. (b) Ancillary reagents and materials... its dating period. (d) Date of manufacture. The date of manufacture of Hepatitis B Surface Antigen...

21 CFR 660.41 - Processing.

Code of Federal Regulations, 2013 CFR

2013-04-01

... STANDARDS FOR DIAGNOSTIC SUBSTANCES FOR LABORATORY TESTS Hepatitis B Surface Antigen § 660.41 Processing. (a... that will reduce the risk of transmitting type B viral hepatitis. (b) Ancillary reagents and materials... its dating period. (d) Date of manufacture. The date of manufacture of Hepatitis B Surface Antigen...

21 CFR 660.41 - Processing.

Code of Federal Regulations, 2012 CFR

2012-04-01

... STANDARDS FOR DIAGNOSTIC SUBSTANCES FOR LABORATORY TESTS Hepatitis B Surface Antigen § 660.41 Processing. (a... that will reduce the risk of transmitting type B viral hepatitis. (b) Ancillary reagents and materials... its dating period. (d) Date of manufacture. The date of manufacture of Hepatitis B Surface Antigen...

21 CFR 660.41 - Processing.

Code of Federal Regulations, 2010 CFR

2010-04-01

... STANDARDS FOR DIAGNOSTIC SUBSTANCES FOR LABORATORY TESTS Hepatitis B Surface Antigen § 660.41 Processing. (a... that will reduce the risk of transmitting type B viral hepatitis. (b) Ancillary reagents and materials... its dating period. (d) Date of manufacture. The date of manufacture of Hepatitis B Surface Antigen...

Modelling of Earthquake History of the Knidos Fault Zone SW Turkey Using in-situ 36Cl Surface Exposure Dating by R

NASA Astrophysics Data System (ADS)

Sahin, S.; Yıldırım, C.; Sarıkaya, M. A.; Tuysuz, O.; Genç, S. C.; Aksoy, M. E.; Doksanaltı, M. E.; Benedetti, L.

2016-12-01

Cosmogenic surface exposure dating is based on the production of rare nuclides in exposed rocks, which interact with cosmic rays. Through modelling of measured 36Cl concentrations, we might obtain information of the history of the earthquake activity. Yet, there are several factors which may impact production of rare nuclides such as geometry of fault, topography, geographic location of study area, temporal variations of the Earth's magnetic field, self-cover and denudation rate on the scarp. Our study area, the Knidos Fault Zone, is located on the Datça Peninsula in the Southwestern Anatolia and contains several normal fault scarps formed within the limestone, which are appropriate to apply cosmogenic chlorine-36 dating. Since it has a well-preserved scarp, we have focused on the Mezarlık Segment of the fault zone, which has an average length of 300 m and height 12-15 m. 128 continuous samples from top to bottom of the fault scarp were collected to carry out analysis of cosmic 36Cl isotopes concentrations. Recent research elucidated each step of the application of this method by the Matlab (e.g. Schlagenhauf et al., 2010). It is vitally helpful to generate models activity of normal faults. We, however, wanted to build a user-friendly program through an open source programing language R that might be able to help those without knowledge of complex math, programming, making calculations as easy as possible. We have set out to obtain accurate conclusions to compare and contrast our results with synthetic profiles and previous studies of limestone fault scarps. The preliminary results indicate at least three major or more earthquakes/earthquakes cluster events occurred on the Mezarlık fault within the past 20 kyr; over 10 meters of displacement took place between early Holocene and late Pleistocene. Estimated ages of those three large slip events are 18.7, 15.1 and 10.8 ka respectively. This study was conducted with the Decision of the Council of Ministers with No. 2013/5387 on the date 30.09.2013 and was done with the permission of Knidos Presidency of excavation in accordance with the scope of Knidos Excavation and Research carried out on behalf of Selçuk University and Ministry of Culture and Tourism. This study was supported by the TÜBİTAK. (Project No: 113Y436)

30 CFR 62.100 - Purpose and scope; effective date.

Code of Federal Regulations, 2012 CFR

2012-07-01

... underground metal, nonmetal, and coal mine subject to the Federal Mine Safety and Health Act of 1977. The... HEALTH REGULATIONS OCCUPATIONAL NOISE EXPOSURE § 62.100 Purpose and scope; effective date. The purpose of...

30 CFR 62.100 - Purpose and scope; effective date.

Code of Federal Regulations, 2014 CFR

2014-07-01

... underground metal, nonmetal, and coal mine subject to the Federal Mine Safety and Health Act of 1977. The... HEALTH REGULATIONS OCCUPATIONAL NOISE EXPOSURE § 62.100 Purpose and scope; effective date. The purpose of...

30 CFR 62.100 - Purpose and scope; effective date.

Code of Federal Regulations, 2010 CFR

2010-07-01

... underground metal, nonmetal, and coal mine subject to the Federal Mine Safety and Health Act of 1977. The... HEALTH REGULATIONS OCCUPATIONAL NOISE EXPOSURE § 62.100 Purpose and scope; effective date. The purpose of...

Timing of maximum glacial extent and deglaciation from HualcaHualca volcano (southern Peru), obtained with cosmogenic 36Cl.

NASA Astrophysics Data System (ADS)

Alcalá, Jesus; Palacios, David; Vazquez, Lorenzo; Juan Zamorano, Jose

2015-04-01

Andean glacial deposits are key records of climate fluctuations in the southern hemisphere. During the last decades, in situ cosmogenic nuclides have provided fresh and significant dates to determine past glacier behavior in this region. But still there are many important discrepancies such as the impact of Last Glacial Maximum or the influence of Late Glacial climatic events on glacial mass balances. Furthermore, glacial chronologies from many sites are still missing, such as HualcaHualca (15° 43' S; 71° 52' W; 6,025 masl), a high volcano of the Peruvian Andes located 70 km northwest of Arequipa. The goal of this study is to establish the age of the Maximum Glacier Extent (MGE) and deglaciation at HualcaHualca volcano. To achieve this objetive, we focused in four valleys (Huayuray, Pujro Huayjo, Mollebaya and Mucurca) characterized by a well-preserved sequence of moraines and roches moutonnées. The method is based on geomorphological analysis supported by cosmogenic 36Cl surface exposure dating. 36Cl ages have been estimated with the CHLOE calculator and were compared with other central Andean glacial chronologies as well as paleoclimatological proxies. In Huayuray valley, exposure ages indicates that MGE occurred ~ 18 - 16 ka. Later, the ice mass gradually retreated but this process was interrupted by at least two readvances; the last one has been dated at ~ 12 ka. In the other hand, 36Cl result reflects a MGE age of ~ 13 ka in Mollebaya valley. Also, two samples obtained in Pujro-Huayjo and Mucurca valleys associated with MGE have an exposure age of 10-9 ka, but likely are moraine boulders affected by exhumation or erosion processes. Deglaciation in HualcaHualca volcano began abruptly ~ 11.5 ka ago according to a 36Cl age from a polished and striated bedrock in Pujro Huayjo valley, presumably as a result of reduced precipitation as well as a global increase of temperatures. The glacier evolution at HualcaHualca volcano presents a high correlation with precipitation cycles of the Altiplano (Tauca / Coipasa phases) and Heinrich 1 / Younger Dryas cold climatic events. Research funded by Cryocrisis project (CGL2012-35858), Government of Spain

10Be and 36Cl Surface Exposure age of the Puerto Banderas Moraine, Lago Argentino, Argentina, 50°S

NASA Astrophysics Data System (ADS)

Becker, R. A.; Ackert, R. P.; Singer, B. S.; Douglass, D. C.; Caffee, M.; Kurz, M.; Mickelson, D. M.; Rabassa, J.

2005-12-01

The Antarctic Cold Reversal (ACR) and Younger Dryas (YD) are prominent late deglacial cool periods expressed in polar ice and high latitude marine sediments between 14.8-12.7 and 12.7-11.5 ka, respectively. Debate centers on the extent to which YD cooling affected the earth`s surface, particularly in the mid- to high latitudes of the Southern Hemisphere. Resolving the timing of late glacial cooling is critical to determining the degree of inter-hemispheric synchroneity as the climate system evolved after the global Last Glaciation Maximum (LGM) 16 ka. The Puerto Banderas moraine was deposited at 50°S in the rain shadow east of the Andes and between LGM moraines 60 km to the east and the present south Patagonian Ice Cap 40 km to the west. It is a sharp-crested ridge 30 km long and 10-15 m high, topped by numerous erratic boulders >1 m high ideally suited for surface exposure dating. Radiocarbon dating provides only broad age limits. A weighted mean of three 14C ages on peat younger than the moraine of 11.7±0.3 cal. ka (2 σ), along with glacier behavior elsewhere in the Andes, led John Mercer to propose that the Puerto Banderas moraine is late glacial, ca. 15 ka. Recent mapping and two additional 14C ages suggest that the moraine may have been deposited in stages between 15.4 and 11.9 ka. New cosmogenic surface exposure ages from the most prominent part of this moraine, however, indicate a considerably younger age. The weighted mean of 10Be ages from quartz in 8 boulders is 11.3±0.7 ka. Moreover, the weighted mean of 36Cl ages from 8 other boulders is 10.9±0.9 ka. The weighted mean age of all 16 boulders is 11.1±0.5 ka. Uncertainties include analytical and production rate contributions. Our previous work in the region suggests that production rates may be 10% higher than expected owing to reduced air pressure during the late glacial and the early Holocene. Thus, the age of 11.1±0.5 ka is a maximum for the Puerto Banderas moraine and although it is possible that it formed after the YD, it is highly unlikely that it was deposited during the ACR. Lago Cardiel, a closed lake basin 175 km to the NE, was highest at 11.7 ka. Marine sediments cored west of the Andes at 41°S show warm sea surface temperatures and low salinity at 11.0 ka, consistent with increased precipitation and glacial erosion. These paleoclimate proxies imply that the Puerto Banderas records southern Patagonian Ice Cap expansion due to increased precipitation, likely tied to focusing of the moisture-laden southern Westerly storm track at 50°S between 12 and 11 ka.

Acute and Subacute Inhalation Toxicity Study in Rats Exposed to Pyrotechnically-Disseminated M18 Red Smoke

DTIC Science & Technology

2017-04-12

ranged from 36 - 39%. Exposure chamber oxygen remained constant at 21%. The animal exposure box temperature ranged from 72 – 73°F and the...0036333, April - September 2015 Chamber Oxygen Chamber Temperature Chamber Relative (N) Exposure Box Exposure Box Relative (N) Exposure No. Date Range...Study No. S.0036333-15, April - September 2015 Chamber Oxygen Chamber Temperature Chamber Relative (N) Exposure Box Exposure Box Relative (N

Maternal residential exposure to agricultural pesticides and birth defects in a 2003 to 2005 North Carolina birth cohort.

PubMed

Rappazzo, Kristen M; Warren, Joshua L; Meyer, Robert E; Herring, Amy H; Sanders, Alison P; Brownstein, Naomi C; Luben, Thomas J

2016-04-01

Birth defects are responsible for a large proportion of disability and infant mortality. Exposure to a variety of pesticides have been linked to increased risk of birth defects. We conducted a case-control study to estimate the associations between a residence-based metric of agricultural pesticide exposure and birth defects. We linked singleton live birth records for 2003 to 2005 from the North Carolina (NC) State Center for Health Statistics to data from the NC Birth Defects Monitoring Program. Included women had residence at delivery inside NC and infants with gestational ages from 20 to 44 weeks (n = 304,906). Pesticide exposure was assigned using a previously constructed metric, estimating total chemical exposure (pounds of active ingredient) based on crops within 500 meters of maternal residence, specific dates of pregnancy, and chemical application dates based on the planting/harvesting dates of each crop. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals for four categories of exposure (<10(th) , 10-50(th) , 50-90(th) , and >90(th) percentiles) compared with unexposed. Models were adjusted for maternal race, age at delivery, education, marital status, and smoking status. We observed elevated ORs for congenital heart defects and certain structural defects affecting the gastrointestinal, genitourinary and musculoskeletal systems (e.g., OR [95% confidence interval] [highest exposure vs. unexposed] for tracheal esophageal fistula/esophageal atresia = 1.98 [0.69, 5.66], and OR for atrial septal defects: 1.70 [1.34, 2.14]). Our results provide some evidence of associations between residential exposure to agricultural pesticides and several birth defects phenotypes. Birth Defects Research (Part A) 106:240-249, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Health assessment for Watkins-Johnson Facility, Scotts Valley, California, Region 9. CERCLIS No. CAD980893234. Preliminary report

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

Not Available

The Watkins-Johnson facility is on the National Priorities List. The facility manufactures electronic components. The environmental sampling conducted to date indicates that the contaminants of concern at the site are predominantly VOCs present in ground water, surface water, and soil. The VOCs present in one or more environmental media include trichloroethylene (TCE); 1,2-dichloroethylene (DCE); tetrachloroethylene perchloroethylene (PCE); vinyl chloride; methylene chloride; 1,1,1-trichloroethane (TCA); and Freon 113. The site is considered to be of potential public health concern because of the risk to human health caused by the possibility of exposure to hazardous substances via ingestion of contaminated ground water.

Erosion during extreme flood events dominates Holocene canyon evolution in northeast Iceland.

PubMed

Baynes, Edwin R C; Attal, Mikaël; Niedermann, Samuel; Kirstein, Linda A; Dugmore, Andrew J; Naylor, Mark

2015-02-24

Extreme flood events have the potential to cause catastrophic landscape change in short periods of time (10(0) to 10(3) h). However, their impacts are rarely considered in studies of long-term landscape evolution (>10(3) y), because the mechanisms of erosion during such floods are poorly constrained. Here we use topographic analysis and cosmogenic (3)He surface exposure dating of fluvially sculpted surfaces to determine the impact of extreme flood events within the Jökulsárgljúfur canyon (northeast Iceland) and to constrain the mechanisms of bedrock erosion during these events. Surface exposure ages allow identification of three periods of intense canyon cutting about 9 ka ago, 5 ka ago, and 2 ka ago during which multiple large knickpoints retreated large distances (>2 km). During these events, a threshold flow depth was exceeded, leading to the toppling and transportation of basalt lava columns. Despite continuing and comparatively large-scale (500 m(3)/s) discharge of sediment-rich glacial meltwater, there is no evidence for a transition to an abrasion-dominated erosion regime since the last erosive event because the vertical knickpoints have not diffused over time. We provide a model for the evolution of the Jökulsárgljúfur canyon through the reconstruction of the river profile and canyon morphology at different stages over the last 9 ka and highlight the dominant role played by extreme flood events in the shaping of this landscape during the Holocene.

Late Pleistocene to Holocene paleoseismicity of the House Range fault from UAV photogrammetry and exposure-age dating

NASA Astrophysics Data System (ADS)

Niemi, N. A.; Stahl, T.; Andreini, J.; Wells, J.; Bunds, M. P.

2016-12-01

The western face of the House Range in Utah is one of the steepest normal fault-bounded blocks in the Basin and Range. In spite of this, clear evidence of recent faulting is limited to a single c. 10 km-long, 1-2 m high scarp at the surface. A drone-based photogrammetric DEM with <10 cm resolution reveals that the fault displaces transgressive Lake Bonneville (c. 20-18 ka) and Provo highstand shorelines (c. 17 cal. ka) by similar amounts, suggesting a single event displacement of c. 1.5 m. Elastic strain models that incorporate shoreline geometry are best-fit by a fault dip of 50-60° in the uppermost crust, whereas previous studies have noted that the fault becomes listric or is truncated by a low-angle fault at depth. Exposure-ages of surface clasts on undeformed alluvial fans suggest that regression from the Provo shoreline occurred rapidly and that the last surface-rupturing earthquake occurred during occupation of the Provo shoreline. This pattern is consistent with other areas in the Great Basin that observe enhanced seismic moment release and earthquake ruptures during late Pleistocene lake regression. We calculate a time-averaged slip rate of 0.1-0.2 mm/yr and minimum recurrence interval of 17 ka. This study highlights the utility of drone surveys and high-resolution geochronology in neotectonic studies and in defining paleoseismic fault parameters.

Erosion during extreme flood events dominates Holocene canyon evolution in northeast Iceland

PubMed Central

Baynes, Edwin R. C.; Attal, Mikaël; Kirstein, Linda A.; Dugmore, Andrew J.; Naylor, Mark

2015-01-01

Extreme flood events have the potential to cause catastrophic landscape change in short periods of time (100 to 103 h). However, their impacts are rarely considered in studies of long-term landscape evolution (>103 y), because the mechanisms of erosion during such floods are poorly constrained. Here we use topographic analysis and cosmogenic 3He surface exposure dating of fluvially sculpted surfaces to determine the impact of extreme flood events within the Jökulsárgljúfur canyon (northeast Iceland) and to constrain the mechanisms of bedrock erosion during these events. Surface exposure ages allow identification of three periods of intense canyon cutting about 9 ka ago, 5 ka ago, and 2 ka ago during which multiple large knickpoints retreated large distances (>2 km). During these events, a threshold flow depth was exceeded, leading to the toppling and transportation of basalt lava columns. Despite continuing and comparatively large-scale (500 m3/s) discharge of sediment-rich glacial meltwater, there is no evidence for a transition to an abrasion-dominated erosion regime since the last erosive event because the vertical knickpoints have not diffused over time. We provide a model for the evolution of the Jökulsárgljúfur canyon through the reconstruction of the river profile and canyon morphology at different stages over the last 9 ka and highlight the dominant role played by extreme flood events in the shaping of this landscape during the Holocene. PMID:25675484

Past Victimizations and Dating Violence Perpetration in Adolescence: The Mediating Role of Emotional Distress and Hostility

ERIC Educational Resources Information Center

Boivin, Sophie; Lavoie, Francine; Hebert, Martine; Gagne, Marie-Helene

2012-01-01

This study aimed to understand the nature of the relationships between three forms of past victimizations (exposure to interparental violence in childhood, sexual harassment by peers since beginning high school, prior experience of dating violence), physical dating violence perpetration by adolescents, and anger-hostility and emotional distress.…

Initial Development of the Teen Screen for Dating Violence: Exploratory Factor Analysis, Rasch Model, and Psychometric Data

ERIC Educational Resources Information Center

Emelianchik-Key, Kelly; Hays, Danica G.; Hill, Tara

2018-01-01

The Teen Screen for Dating Violence (TSDV) is an assessment that examines adolescent dating violence perpetration and victimization, perception and exposure to violence, and support systems. Through assessment, adolescents who are at high risk could be identified for prevention and early intervention. This article presents the development,…

76 FR 9578 - National Center for Environmental Health/Agency for Toxic Substances and Disease Registry (NCEH...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-18

... National Conversation on Public Health and Chemical Exposures Leadership Council Meeting Time and Date: 8... Conversation on Public Health and Chemical Exposures Leadership Council. The National Conversation on Public... public's health from harmful chemical exposures. The Leadership Council provides overall guidance to the...

Integrative investigations on sediments in the Belauer See catchment (northern Germany)

NASA Astrophysics Data System (ADS)

Dreibrodt, Stefan

2015-04-01

The Holocene history of lake development, catchment vegetation, soil formation and human impact since the onset of the Neolithic period was reconstructed via the analysis of sediment sequences at Lake Belau (northern Germany). The chronology of the annually laminated lake sediment sequence was established via varve counts, radiocarbon dating and tephra analysis. Sequences of colluvial sediments and buried soils studied in 19 large exposures and supplementing auger cores within the lake catchment area were dated via radiocarbon dating and archaeological dating of embedded artifacts. The long term development of the lake status was found to be strongly influenced by local human activity. This is indicated by coincidence of phases of landscape openness deduced from pollen data with input of detritus and solutes into the lake. A comparison with palaeo-climate reconstructions reveals that calcite precipitation in the lake reflects climate variability at least to a certain degree. Calibrating the sediment record of the sub-recent lake sediments (micro-facies) on limnological and meteorological records discovered the influence of the NAO as well as solar activity on the limnological processes during the last century reflected by distinguished sedimentation patterns. A comparative study of additional laminated surface sediment sequences from northern Germany corroborates the results. A high resolution reconstruction of Neolithic weather conditions in northern Germany based on the varves of Lake Belau and Lake Poggensee was facilitated by the calibration. The quantitative records of sediments originating from soil erosion (colluvial sediments, allochthonous input into the lake) illustrate the dominance of short distance surface processes (slopes) acting in Holocene mid-latitude landscapes. Coincidence of gully incision in the lake catchment area and increased allochthonous input into the lake indicates the former occurrence of hydrological high energy runoff events (e. g. in the 14th century or at ca. 200 cal BC) whose regional significance is testable via comparative investigations in additional lake catchments.

Specific Caleosin/Peroxygenase and Lipoxygenase Activities Are Tissue-Differentially Expressed in Date Palm (Phoenix dactylifera L.) Seedlings and Are Further Induced Following Exposure to the Toxin 2,3,7,8-tetrachlorodibenzo-p-dioxin.

PubMed

Hanano, Abdulsamie; Almousally, Ibrahem; Shaban, Mouhnad; Rahman, Farzana; Hassan, Mehedi; Murphy, Denis J

2016-01-01

Two caleosin/peroxygenase isoforms from date palm, Phoenix dactylifera L., PdCLO2 and PdCLO4, were characterized with respect to their tissue expression, subcellular localization, and oxylipin pathway substrate specificities in developing seedlings. Both PdCLO2 and PdCLO4 had peroxygenase activities that peaked at the mid-stage (radicle length of 2.5 cm) of seedling growth and were associated with the lipid droplet (LD) and microsomal fractions. Recombinant PdCLO2 and PdCLO4 proteins heterologously expressed in yeast cells were localized in both LD and microsomal fractions. Each of the purified recombinant proteins exhibited peroxygenase activity but they were catalytically distinct with respect to their specificity and product formation from fatty acid epoxide and hydroxide substrates. We recently showed that date palm CLO genes were upregulated following exposure to the potent toxin, 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD) (Hanano et al., 2016), and we show here that transcripts of 9- and 13-lipoxygenase (LOX) genes were also induced by TCDD exposure. At the enzyme level, 9-LOX and 13-LOX activities were present in a range of seedling tissues and responded differently to TCDD exposure, as did the 9- and 13-fatty acid hydroperoxide reductase activities. This demonstrates that at least two branches of the oxylipin pathway are involved in responses to the environmental organic toxin, TCDD in date palm.

Reply to comment received from J. Herget et al. regarding ;Complex patterns of glacier advances during the late glacial in the Chagan Uzun Valley, Russian Altai; by Gribenski et al. (2016), Quaternary Science Reviews 149, 288-305

NASA Astrophysics Data System (ADS)

Gribenski, Natacha; Lukas, Sven; Stroeven, Arjen P.; Jansson, Krister N.; Harbor, Jonathan M.; Blomdin, Robin; Ivanov, Mikhail N.; Heyman, Jakob; Petrakov, Dmitry A.; Rudoy, Alexei; Clifton, Tom; Lifton, Nathaniel A.; Caffee, Marc W.

2017-07-01

We thank Herget et al. (2017) for their keen interest in our study about the paleoglacial history of the Chagan Uzun Valley, in the Russian Altai (Gribenski et al., 2016). In our study, we proposed a detailed chronological and glaciodynamic reconstruction of a succession of glacial events represented by prominent moraine complexes, based on remotely-sensed data and field-geomorphological mapping, sedimentological logging, and cosmogenic 10Be and 26Al surface exposure dating of glacially-transported boulders. Herget et al. (2017) express skepticism about the outermost moraine complex dated in our study (CUMC 1; Gribenski et al., 2016), which slightly predates 19 thousand years (ka), during marine isotope stage (MIS) 2. To quote: "we suspect that their claim of regional climatic significance-that the ∼19 ka Chagan-Uzun moraine they dated can be used to show that the local LGM and regional LGM were the same, and occurred during MIS 2-may be premature" (Herget et al., 2017: p. 1). Their comment appears to relate to an ongoing debate regarding the timing of maximum glaciation in Central Asia during the last glacial cycle, however it is based on misinterpretations of our paper.

One Isotope, Two Tales: using plant and cosmogenic 14C to constrain Holocene glacier activity on Baffin Island.

NASA Astrophysics Data System (ADS)

Pendleton, S.; Miller, G. H.; Lifton, N. A.; Young, N. E.

2017-12-01

As the cryosphere continues to undergo rapid and accelerating change, it is more important than ever to understand past glacier activity to predict the future of the cryosphere. However, continuous Holocene glacier records are notoriously difficult to reconstruct because an advancing glacier will re-incorporate previous deposits so that moraines typically only record the farthest downvalley glacier expansion. Here we combine dates of ice margin advance from in situ dead vegetation with in situ cosmogenic 14C (in situ 14C) from preserved bedrock surfaces at the same locations to further constrain the timing of ice-free episodes during the Holocene following deglaciation on southern Baffin Island. Radiocarbon ages from recently exposed in situ plants suggest that ice last advanced over sample locations at 9.4, 9.2, 9.0, and 3.7 ka and that they remained ice covered until modern times. Associated in situ 14C inventories are variable, but well above background levels, suggesting some amount of Holocene in situ 14C production. Using plant 14C ages representing the beginning of ice coverage and in situ 14C inventories representative of exposure prior to ice coverage, a simple model of cosmogenic in situ 14C production (accounting for muon production through ice) provides constraints timing and duration of ice-free times at sample locations prior to their most recent burial. Using conservative Holocene ice thicknesses, the locations buried at 9.4, 9.2, and 9.0 ka require, at minimum, 1000 years of pre-burial exposure to match the observed in situ 14C inventory. This suggests these locations were ice free by at least 10 ka and likely earlier. The in situ 14C inventory at the location buried at 3.7 ka limits prior exposure to 2000 years, suggesting that this location experienced more complex Holocene ice cover/burial history. These pilot data show that valuable information regarding periods of exposure is contained within in situ 14C inventories. Additional paired plant and in situ 14C analyses currently underway will provide further constraints on the timing and duration of Holocene exposure. The combination of these two dating techniques supplies some of the first constraints on both ice cover and exposure and provides much needed information about the evolution of glaciers on southern Baffin Island following deglaciation.

Adolescent Conflict as a Developmental Process in the Prospective Pathway from Exposure to Interparental Violence to Dating Violence

PubMed Central

Narayan, Angela J.; Englund, Michelle M.; Carlson, Elizabeth A.; Egeland, Byron

2013-01-01

Within a developmental psychopathology framework, the current study examined adolescent conflict (age 16) with families, best friends, and dating partners as mediators in the prospective pathway from exposure to interparental violence (EIPV) in early childhood (0–64 months) to dating violence perpetration and victimization in early adulthood (age 23). Adolescent conflict was predicted to partially mediate EIPV and dating violence with significant direct paths from EIPV to dating violence, given the extant literature on the salience of early childhood EIPV for later maladjustment. Participants (N = 182; 99 males, 83 females; 67% Caucasian, 11% African-American, 18% other, 4% unreported) were drawn from a larger prospective study of high-risk mothers (aged 12–34 years) that followed their children from birth through adulthood. EIPV and adolescent conflict were rated from interviews with mothers and participants, and dating violence (physical perpetration and victimization) was assessed with the Conflict Tactics Scale. Path analyses showed that EIPV in early childhood (a) directly predicted dating violence perpetration in early adulthood and (b) predicted conflict with best friends, which in turn predicted dating violence perpetration. Although mediation of best friend conflict was not evident, indirect effects of EIPV to dating violence were found through externalizing behaviors in adolescence and life stress in early adulthood. Findings highlight that conflict with best friends is affected by EIPV and predicts dating violence, suggesting that it may be a promising target for relationship-based interventions for youth with EIPV histories. Furthermore, deleterious early experiences and contemporaneous risk factors are salient predictors of dating violence. PMID:23979004

Exposure to Spousal Violence in the Family, Attitudes and Dating Violence Perpetration Among High School Students in Port-au-Prince.

PubMed

Gage, Anastasia J

2016-09-01

This study examined the associations of exposure to spousal violence in the family and personal and peer attitudes with dating violence (DV) perpetration among high school students in Port-au-Prince, Haiti. Participants were 342 high school students in Grades 10 to 12 who stated that they had ever been on a date. Multiple linear regression methods were used to examine correlates of the scale of DV perpetration. Findings showed that personal acceptance of DV mediated the association between exposure to wife-perpetrated and husband-perpetrated spousal violence in the family and DV perpetration for girls. Boys who were exposed to husband-perpetrated spousal violence in the family had significantly higher levels of psychological DV perpetration than those who were not. Contrary to expectations, exposure to wife-perpetrated spousal violence in the family was negatively associated with psychological and physical/sexual DV perpetration by boys, after controlling for other factors. Overall, perceived peer tolerance of DV was more strongly associated with DV perpetration than personal tolerance of DV, and was the only significant correlate of psychological DV perpetration for girls. Perceived peer attitudes also moderated the association between boys' exposure to spousal violence in the family and DV perpetration. Implications for future research and policy are discussed. © The Author(s) 2015.

Comparison of gestational dating methods and implications ...

EPA Pesticide Factsheets

OBJECTIVES: Estimating gestational age is usually based on date of last menstrual period (LMP) or clinical estimation (CE); both approaches introduce potential bias. Differences in methods of estimation may lead to misclassificat ion and inconsistencies in risk estimates, particularly if exposure assignment is also gestation-dependent. This paper examines a'what-if' scenario in which alternative methods are used and attempts to elucidate how method choice affects observed results.METHODS: We constructed two 20-week gestational age cohorts of pregnancies between 2000 and 2005 (New Jersey, Pennsylvania, Ohio, USA) using live birth certificates : one defined preterm birth (PTB) status using CE and one using LMP. Within these, we estimated risk for 4 categories of preterm birth (PTBs per 106 pregnancies) and risk differences (RD (95% Cl s)) associated with exposure to particulate matter (PM2. 5).RESULTS: More births were classified preterm using LMP (16%) compared with CE (8%). RD divergences increased between cohorts as exposure period approached delivery. Among births between 28 and 31 weeks, week 7 PM2.5 exposure conveyed RDs of 44 (21 to 67) for CE and 50 (18 to 82) for LMP populations, while week 24 exposure conveyed RDs of 33 (11 to 56) and -20 (-50 to 10), respectively.CONCLUSIONS: Different results from analyses restricted to births with both CE and LMP are most likely due to differences in dating methods rather than selection issues. Results are sensitive t

The sexually dimorphic impact of maltreatment on cortical thickness, surface area and gyrification.

PubMed

Kelly, Philip A; Viding, Essi; Puetz, Vanessa B; Palmer, Amy L; Samuel, Sophie; McCrory, Eamon J

2016-09-01

An extensive literature has detailed how maltreatment experience impacts brain structure in children and adolescents. However, there is a dearth of studies on the influence of maltreatment on surface based indices, and to date no study has investigated how sex influences the impact of maltreatment on cortical thickness, surface area and local gyrification. We investigated sex differences in these measures of cortical structure in a large community sample of children aged 10-14 years (n = 122) comprising 62 children with verified maltreatment experience and 60 matched non-maltreated controls. The maltreated group relative to the controls presented with a pattern of decreased cortical thickness within a region of right anterior cingulate, orbitofrontal cortex and superior frontal gyrus; decreased surface area within the right inferior parietal cortex; and increased local gyrification within left superior parietal cortex. This atypical pattern of cortical structure was similar across males and females. An interaction between maltreatment exposure and sex was found only in local gyrification, within two clusters: the right tempo-parietal junction and the left precentral gyrus. These findings suggest that maltreatment impacts cortical structure in brain areas associated with emotional regulation and theory of mind, with few differences between the sexes.

Potential environmental implications of nanoscale zero-valent iron particles for environmental remediation.

PubMed

Jang, Min-Hee; Lim, Myunghee; Hwang, Yu Sik

2014-01-01

Nanoscale zero-valent iron (nZVI) particles are widely used in the field of various environmental contaminant remediation. Although the potential benefits of nZVI are considerable, there is a distinct need to identify any potential risks after environmental exposure. In this respect, we review recent studies on the environmental applications and implications of nZVI, highlighting research gaps and suggesting future research directions. Environmental application of nZVI is briefly summarized, focusing on its unique properties. Ecotoxicity of nZVI is reviewed according to type of organism, including bacteria, terrestrial organisms, and aquatic organisms. The environmental fate and transport of nZVI are also summarized with regards to exposure scenarios. Finally, the current limitations of risk determination are thoroughly provided. The ecotoxicity of nZVI depends on the composition, concentration, size and surface properties of the nanoparticles and the experimental method used, including the species investigated. In addition, the environmental fate and transport of nZVI appear to be complex and depend on the exposure duration and the exposure conditions. To date, field-scale data are limited and only short-term studies using simple exposure methods have been conducted. In this regard, the primary focus of future study should be on 1) the development of an appropriate and valid testing method of the environmental fate and ecotoxicity of reactive nanoparticles used in environmental applications and 2) assessing their potential environmental risks using in situ field scale applications.

Potential environmental implications of nanoscale zero-valent iron particles for environmental remediation

PubMed Central

Jang, Min-Hee; Lim, Myunghee; Hwang, Yu Sik

2014-01-01

Objectives Nanoscale zero-valent iron (nZVI) particles are widely used in the field of various environmental contaminant remediation. Although the potential benefits of nZVI are considerable, there is a distinct need to identify any potential risks after environmental exposure. In this respect, we review recent studies on the environmental applications and implications of nZVI, highlighting research gaps and suggesting future research directions. Methods Environmental application of nZVI is briefly summarized, focusing on its unique properties. Ecotoxicity of nZVI is reviewed according to type of organism, including bacteria, terrestrial organisms, and aquatic organisms. The environmental fate and transport of nZVI are also summarized with regards to exposure scenarios. Finally, the current limitations of risk determination are thoroughly provided. Results The ecotoxicity of nZVI depends on the composition, concentration, size and surface properties of the nanoparticles and the experimental method used, including the species investigated. In addition, the environmental fate and transport of nZVI appear to be complex and depend on the exposure duration and the exposure conditions. To date, field-scale data are limited and only short-term studies using simple exposure methods have been conducted. Conclusions In this regard, the primary focus of future study should be on 1) the development of an appropriate and valid testing method of the environmental fate and ecotoxicity of reactive nanoparticles used in environmental applications and 2) assessing their potential environmental risks using in situ field scale applications. PMID:25518840

75 FR 59727 - National Center for Environmental Health/Agency for Toxic Substances and Disease Registry (NCEH...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-28

... National Conversation on Public Health and Chemical Exposures Leadership Council Meeting Time and Date: 9 a... Chemical Exposures Leadership Council, which is convened by RESOLVE, a non-profit independent facilitator... exposures. The Leadership Council provides overall guidance to the National Conversation project and is...

National Survey of Children's Exposure to Violence. Juvenile Justice Bulletin

ERIC Educational Resources Information Center

Finkelhor, David; Turner, Heather; Ormrod, Richard; Hamby, Sherry; Kracke, Kristen

2009-01-01

This Bulletin discusses the National Survey of Children's Exposure to Violence (NatSCEV), the most comprehensive nationwide survey of the incidence and prevalence of children's exposure to violence to date, sponsored by the Office of Juvenile Justice and Delinquency Prevention (OJJDP) and supported by the Centers for Disease Control and Prevention…

Approaches to systematic assessment of environmental exposures posed at hazardous waste sites in the developing world: the Toxic Sites Identification Program.

PubMed

Ericson, Bret; Caravanos, Jack; Chatham-Stephens, Kevin; Landrigan, Philip; Fuller, Richard

2013-02-01

In the developing world, environmental chemical exposures due to hazardous waste sites are poorly documented. We describe the approach taken by the Blacksmith Institute's Toxic Sites Identification Program in documenting environmental chemical exposures due to hazardous waste sites globally, identifying sites of concern and quantifying pathways, populations, and severity of exposure. A network of local environmental investigators was identified and trained to conduct hazardous waste site investigations and assessments. To date, 2,095 contaminated sites have been identified within 47 countries having an estimated population at risk of 71,500,000. Trained researchers and investigators have visited 1,400 of those sites. Heavy metals are the leading primary exposures, with water supply and ambient air being the primary routes of exposure. Even though chemical production has occurred largely in the developed world to date, many hazardous waste sites in the developing world pose significant hazards to the health of large portions of the population. Further research is needed to quantify potential health and economic consequences and identify cost-effective approaches to remediation.

Latest Quaternary rapid river incision across an inactive fold in the northern Chinese Tian Shan foreland

NASA Astrophysics Data System (ADS)

Lu, Honghua; Cheng, Lu; Wang, Zhen; Zhang, Tianqi; Lü, Yanwu; Zhao, Junxiang; Li, Youli; Zheng, Xiangmin

2018-01-01

This work focuses on the incision process over the Tuostai anticline, a fold of the proximal structure Belt I in the northern Chinese Tian Shan foreland, where the Sikeshu River has incised deeply into the alluvial gravels and the fold's underlying bedrock strata. Field investigation and geomorphic mapping define five terraces of the Sikeshu River (designated as T1 to T5 from oldest to youngest) preserved within the Tuostai anticline. 10Be surface exposure dating and optically stimulated luminescence dating constrain stabilization of the highest three terrace surfaces at about 80 ka (T1), 16 ka (T2), and 15 ka (T3), respectively. Around 16 ka, the calculated river incision rates significantly increase from <2 mm/yr to >6 mm/yr. Undeformed longitudinal profiles of terraces T2, T3 and T4 over the Tuostai anticline suggest that this structure may have been tectonically inactive since stabilization of these three terraces. We thus think that the observed rapid river incision over the Tuostai anticline has not been largely forced by tectonic uplift. Instead, the progressively warmer and wetter palaeoclimatic condition within the Tian Shan range and its surrounding area during the period of ∼20-10 ka may have enhanced river incision across the Tuostai anticline. A reduced sediment/water ratio might have lowered the gradient of the Sikeshu River.

Reaching and abandoning the furthest ice extent during the Last Glacial Maximum in the Alps

NASA Astrophysics Data System (ADS)

Ivy-Ochs, Susan; Wirsig, Christian; Zasadni, Jerzy; Hippe, Kristina; Christl, Marcus; Akçar, Naki; Schluechter, Christian

2016-04-01

During the Last Glacial Maximum (LGM) in the European Alps (late Würm) local ice caps and extensive ice fields in the high Alps fed huge outlet glaciers that occupied the main valleys and extended onto the forelands as piedmont lobes. Records from numerous sites suggest advance of glaciers beyond the mountain front by around 30 ka (Ivy-Ochs 2015 and references therein). Reaching of the maximum extent occurred by about 27-26 ka, as exemplified by dates from the Rhein glacier area (Keller and Krayss, 2005). Abandonment of the outermost moraines at sites north and south of the Alps was underway by about 24 ka. In the high Alps, systems of transection glaciers with transfluences over many of the Alpine passes dominated, for example, at Grimsel Pass in the Central Alps (Switzerland). 10Be exposure ages of 23 ± 1 ka for glacially sculpted bedrock located just a few meters below the LGM trimline in the Haslital near Grimsel Pass suggest a pulse of ice surface lowering at about the same time that the foreland moraines were being abandoned (Wirsig et al., 2016). Widespread ice surface lowering in the high Alps was underway by no later than 18 ka. Thereafter, glaciers oscillated at stillstand and minor re-advance positions on the northern forelands for several thousand years forming the LGM stadial moraines. Final recession back within the mountain front took place by 19-18 ka. Recalculation to a common basis of all published 10Be exposure dates for boulders situated on LGM moraines suggests a strong degree of synchrony for the timing of onset of ice decay both north and south of the Alps. Ivy-Ochs, S., 2015, Cuadernos de investigación geográfica 41: 295-315. Keller, O., Krayss, E., 2005, Vierteljahrschr. Naturforsch. Gesell. Zürich 150: 69-85. Wirsig, C. et al., 2016, J. Quat. Sci. 31: 46-59.

Post-glacial rock avalanches in the Obersee Valley, Glarner Alps, Switzerland

NASA Astrophysics Data System (ADS)

Nagelisen, Jan; Moore, Jeffrey R.; Vockenhuber, Christoph; Ivy-Ochs, Susan

2015-06-01

The geological record of prehistoric rock avalanches provides invaluable data for assessing the hazard posed by these rare but destructive mass movements. Here we investigate two large rock avalanches in the Obersee valley of the Glarner Alps, Switzerland, providing detailed mapping of landslide and related Quaternary phenomena, revised volume estimates for each event, and surface exposure dating of rock avalanche deposits. The Rautispitz rock avalanche originated from the southern flank of the Obersee valley, releasing approximately 91 million m3 of limestone on steeply-dipping bedding planes. Debris had maximum horizontal travel distance of ~ 5000 m, a fahrboeschung angle (relating fall height to length) of 18°, and was responsible for the creation of Lake Obersee; deposits are more than 130 m thick in places. The Platten rock avalanche encompassed a source volume of 11 million m3 sliding from the northern flank of the Obersee valley on similar steeply-dipping limestone beds (bedrock forms a syncline under the valley). Debris had a maximum horizontal travel distance of 1600 m with a fahrboeschung angle of 21°, and is more than 80 m thick in places. Deposits of the Platten rock avalanche are superposed atop those from the Rautispitz event at the end of the Obersee valley where they dam Lake Haslensee. Runout for both events was simulated using the dynamic analysis code DAN3D; results showed excellent match to mapped deposit extents and thickness and helped confirm the hypothesized single-event failure scenarios. 36Cl cosmogenic nuclide surface exposure dating of 13 deposited boulders revealed a Younger Dryas age of 12.6 ± 1.0 ka for the Rautispitz rock avalanche and a mid-Holocene age of 6.1 ± 0.8 ka for the Platten rock avalanche. A seismological trigger is proposed for the former event due to potentially correlated turbidite deposits in nearby Lake Zurich.

Evidence for Multiple Late Quaternary Glaciations in the Southernmost Cordillera Blanca, Peru

NASA Astrophysics Data System (ADS)

Smith, J. A.; Rodbell, D. T.; Ramage, J. M.

2007-12-01

Surface-exposure dating with in-situ-produced cosmogenic isotopes has provided the basis for a growing framework of glacial chronologies in the tropical Andes. In the Peruvian Andes, long chronologies (>400 ka) with relatively small local last glacial maximum (LLGM) advances have been reported for the central Cordillera Blanca (ca. 9°30'S) and Junin Plain (11°00'S), whereas preliminary data suggest a shorter record (<40 ka) in the intervening Cordillera Huayhuash (10°15'S). These seemingly contradictory findings raise several questions: Was the LLGM a relatively minor event in the Peruvian Andes, far exceeded by bigger, older advances? Which combination of geographic and geomorphic factors increases the likelihood that evidence of older advances will be preserved? With these questions in mind, we sought a site with both high peaks and a high-altitude plateau. The glaciated Nevado Jeulla Rajo massif (10°00'S, 77°16'W, peaks ca. 5600 masl) marks the southern end of the Cordillera Blanca and the Callejon de Huaylas valley in the central Peruvian Andes. The Conococha Plain (ca. 4050 masl) borders the western side of the massif. Large lateral moraines extend onto the Conococha Plain from the west-facing valleys and multiple moraine loops lie upvalley, closer to active ice margins. Surface-exposure dating (10Be) indicates that the largest lateral moraines from Jeullesh Valley are compound features deposited during the LLGM (ca. 30 ka) and a late-glacial readvance (ca. 16 ka). The LLGM/late-glacial moraines cross-cut an older pair of lateral moraines (ca. 70 ka) that may provide evidence for a smaller advance during marine isotope stage 4. Although the LLGM/late-glacial moraines are impressively large (ca. 150 m high), they do not represent the maximum ice extent in the region. Fluvial outwash deposits beyond the termini of the moraines on the Conococha Plain are underlain by lodgement till that is up to 20 m thick and extends ca. 6 km across the width of the Plain to the Rió Santa. The wide distribution of the till suggests that at least one older glaciation was far more extensive than any of the late Quaternary advances that we have dated by 10Be. The combination of high peaks, a high-altitude plateau, and an active fault may be ideal for enhancing preservation of older moraines and till deposits.

Epidemiology of recreational exposure to freshwater cyanobacteria – an international prospective cohort study

PubMed Central

Stewart, Ian; Webb, Penelope M; Schluter, Philip J; Fleming, Lora E; Burns, John W; Gantar, Miroslav; Backer, Lorraine C; Shaw, Glen R

2006-01-01

Background Case studies and anecdotal reports have documented a range of acute illnesses associated with exposure to cyanobacteria and their toxins in recreational waters. The epidemiological data to date are limited; we sought to improve on the design of some previously conducted studies in order to facilitate revision and refinement of guidelines for exposure to cyanobacteria in recreational waters. Methods A prospective cohort study was conducted to investigate the incidence of acute symptoms in individuals exposed, through recreational activities, to low (cell surface area <2.4 mm2/mL), medium (2.4–12.0 mm2/mL) and high (>12.0 mm2/mL) levels of cyanobacteria in lakes and rivers in southeast Queensland, the central coast area of New South Wales, and northeast and central Florida. Multivariable logistic regression analyses were employed; models adjusted for region, age, smoking, prior history of asthma, hay fever or skin disease (eczema or dermatitis) and clustering by household. Results Of individuals approached, 3,595 met the eligibility criteria, 3,193 (89%) agreed to participate and 1,331 (37%) completed both the questionnaire and follow-up interview. Respiratory symptoms were 2.1 (95%CI: 1.1–4.0) times more likely to be reported by subjects exposed to high levels of cyanobacteria than by those exposed to low levels. Similarly, when grouping all reported symptoms, individuals exposed to high levels of cyanobacteria were 1.7 (95%CI: 1.0–2.8) times more likely to report symptoms than their low-level cyanobacteria-exposed counterparts. Conclusion A significant increase in reporting of minor self-limiting symptoms, particularly respiratory symptoms, was associated with exposure to higher levels of cyanobacteria of mixed genera. We suggest that exposure to cyanobacteria based on total cell surface area above 12 mm2/mL could result in increased incidence of symptoms. The potential for severe, life-threatening cyanobacteria-related illness is likely to be greater in recreational waters that have significant levels of cyanobacterial toxins, so future epidemiological investigations should be directed towards recreational exposure to cyanotoxins. PMID:16606468

Toxicity of 2,6-Di-tert-butyl-4-Nitrophenol (DBNP).

PubMed

Alexander, W K; Briggs, G B; Still, K R; Jederberg, W W; MacMahon, K; Baker, W H; Mackerer, C

2001-04-01

U.S. Navy submarines reported a yellowing of metal surfaces on their internal surfaces. The yellowing was initially identified on the painted steel bulkheads but further examination indicated that it was not limited to steel surfaces and included bedding, thread tape, Formica, plastisol covered hand-wheels, and aluminum lockers. Crew members also reported to the medical department that their skin turned yellow when they came in contact with these contaminated surfaces and requested information on the effects of exposure. Studies conducted by General Dynamics' Electric Boat Division (EBD) determined that the agent was 2,6-Di-tertbutyl-4-Nitrophenol (DBNP). 2,6-Di-butylphenol (DBP) is an antioxidant additive used in lubricating oils and hydraulic fluids. In the enclosed atmosphere of a submarine, the oil mist could be spread throughout the boat by venting the lube oil to the atmosphere. Submarines use electrostatic precipitators (ESP) to clean the air of particulate materials. During passage through the ESP, oil mist containing DBP is nitrated to DBNP, which is then moved throughout the boat in the ventilation system. Analysis of the EBD data indicated 24-hour exposure concentrations to be in the range of <3.0 to 122 ppb in the laboratory and submarine settings. Submarine crews may be exposed to these concentrations for as many as 24 hours/ day for 90 days during underway periods. Toxicity studies regarding the oral and dermal uptake of DBNP were conducted. From the literature the lethal dose to 50 percent of the population (LD50) of DBNP (rat) was reported by Vesselinovitch et al. in 1961 to be 500 mg/kg. Our studies indicated that the LD50 is in the range of 80 mg/kg in the rat. Our work also includes dermal absorption studies, which indicated that DBNP is not well absorbed through intact skin. Within this study, no no-observable adverse effect level (NOAEL) or lowest observable adverse effect level (LOAEL) was identified. Calculation of a reference dose was completed using standard methods based on the LD50 as a numerator with several uncertainty and modifying factors. EBD's determination of airborne concentrations aboard submarines fall in the range of these anticipated allowable concentrations and could indicate significant chronic exposures. No adverse effects from DBNP exposures have been reported to date.

Carbon monoxide exposures in New York City following Hurricane Sandy in 2012.

PubMed

Chen, B C; Shawn, L K; Connors, N J; Wheeler, K; Williams, N; Hoffman, R S; Matte, T D; Smith, S W

2013-11-01

On October 29, 2012, Hurricane Sandy made landfall and devastated New York's metropolitan area, causing widespread damage to homes and the utility infrastructure. Eight days later, snow and freezing temperatures from a nor'easter storm delayed utility restoration. To examine carbon monoxide (CO) exposures in the 2 weeks following Hurricane Sandy. Methods. This was a retrospective review of prospectively collected, standardized, and de-identified data sets. CO exposures and poisonings identified from two electronic surveillance systems, the New York City Poison Control Center (NYCPCC) and New York City's Syndromic Surveillance Unit, were compared with CO exposures from identical dates in 2008-2011. Data collected from the poison center included exposure type, CO source, poisoning type, treatment, and outcomes. Data collected from the Syndromic Surveillance Unit cases, which were identified by CO-related chief complaints presenting to NYC hospitals, included visit date and time, and patient demographics. Four hundred thirty-seven CO exposures were reported to the NYCPCC, 355 from NYC callers, and the remainder from surrounding counties, which represented a significant increase when compared with CO exposures from identical dates in the preceding 4 years (p < 0.001). The total cases that were reported to the NYCPCC in 2008, 2009, 2010, and 2011 were 18, 13, 24, and 61, respectively. Excluding a single apartment fire that occurred (n = 311), the more common sources of CO were grilling indoors (26.2%) and generators (17.5%). Syndromic surveillance captured 70 cases; 6 cases were captured by both data sets. CO exposures following weather-related disasters are a significant public health concern, and the use of fuel-burning equipment is a clear source of storm-related morbidity and mortality. Multiple real-time epidemiologic surveillance tools are useful in estimating the prevalence of CO exposure and poisoning and are necessary to assist public health efforts to prevent CO poisoning during and after disasters.

Comparison of Glacial Records From 10°S and 11°S in the Peruvian Andes Suggests Similar Forcings but Different Local Influences

NASA Astrophysics Data System (ADS)

Smith, J. A.; Rodbell, D. T.

2010-12-01

Moraine records of glaciation from three sites in the central Peruvian Andes are broadly consistent over the last glacial cycle (since MIS 5). Surface-exposure dating (10Be) of moraines east and west of Lake Junin (11°00'S, 76°00'W, 4082 masl) and 180 km northwest at the Nevado Jeulla Rajo (NJR) massif (10°00'S, 77°16'W) at the southern end of the Cordillera Blanca suggests a link between glacial advances and increased precipitation associated with Heinrich events. On the eastern side of Lake Junin, the most extensive moraines are >150 ka, but end moraines farther upvalley date to the local last glacial maximum (LLGM, 25-30 ka) and a late-glacial stillstand or readvance (14-18 ka). Surface-exposure ages on a moraine and bedrock in the Santuario Nacional Bosque de Piedras de Huayllay (BPH) on the western side of Lake Junin (10°59'S, 76°20'W) are consistent with 10Be ages on younger moraines on the eastern side: ~26 and ~20 ka on two quartz boulders, ~14-15 ka on four ignimbrite boulders, and ~45 ka on bedrock below a trimline in the valley wall. The NJR massif (ca. 5600 masl) hosts a number of small glaciers within a cirque on its southwestern face; large lateral moraines extend onto the Conococha Plain (ca. 4050 masl) from west-facing valleys. Fault scarps on moraines and valley floors on the western side of NJR show the trace of the active, west-dipping Cordillera Blanca Normal Fault (CBNF). At NJR, 10Be ages indicate that the largest lateral moraines were deposited during similar intervals (27-32 ka and 15-18 ka) to the younger moraines in the eastern Junin valleys and BPH. Differences between the Junin/BPH and NJR records are intriguing. NJR lacks the morphologically distinct pre-MIS 5 moraines that are present in valleys east of Lake Junin, although the Conococha Plain adjacent to NJR is underlain by till and outwash that is likely >50 ka, based on 10Be ages of surface cobbles. At NJR, avulsion of two glacial valleys preserved older, smaller pairs of lateral moraines that are cross-cut by larger, younger moraines. One pair of cross-cut moraines has been dated (56-65 ka) and may be the first geomorphologically distinct evidence of an advance during MIS 4 identified in the region; correlative moraines were apparently not preserved in the Junin valleys. The changes in ice-flow direction at NJR may be related to movement on the CBNF that changed the slope of the Conococha Plain onto which ice flowed. We are in the process of dating additional cross-cutting moraines and moraines offset by the CBNF to gain a better understanding of the timing of the ice-flow shifts. Numerical dating of faulted moraines also provides a means of determining apparent slip rates on a fault. Preliminary results at NJR suggest an apparent slip rate of 2.2-2.8 mm/yr for the CBNF where it offsets one of the late-glacial moraines (15-18 ka).

Repeated exposure to antibiotics in infancy: a predisposing factor for juvenile idiopathic arthritis or a sign of this group's greater susceptibility to infections?

PubMed

Arvonen, Miika; Virta, Lauri J; Pokka, Tytti; Kröger, Liisa; Vähäsalo, Paula

2015-03-01

Previous exposure to antibiotics has been associated with the pathogenesis of several autoimmune diseases. Our objective was to explore whether childhood exposure to antibiotics would be associated with the risk of developing juvenile idiopathic arthritis (JIA). The material was collected from national registers containing all children born in 2000-2010 in Finland and diagnosed with JIA by the end of December 2012 (n = 1298) and appropriate controls (n = 5179) matched for age, sex, and place of birth. All purchases of antibiotics were collected from birth until the index date (i.e., the date of special reimbursement for JIA medications). A conditional logistic regression was performed to evaluate the association between the exposure to antibiotics and the risk of JIA. The risk of JIA increased with the number of antibiotic purchases from birth to the index date: for ≥ 1 purchases versus none, OR 1.6, 95% CI 1.3-1.9 with an upward trend in OR (p < 0.001). Antibiotic groups lincosamides and cephalosporins showed the strongest association with JIA (OR 6.6, 95% CI 3.7-11.7, and OR 1.6, 95% CI 1.4-1.8, respectively). Overall exposure to antibiotics before 2 years of age was associated with an increased risk of JIA (OR 1.4, 95% CI 1.2-1.6), with the trend test of OR (p < 0.001). Previous early and repeated exposure to antibiotics may predispose individuals to develop JIA. Alternatively, the apparent association may reflect shared susceptibility to infections and JIA.

Surface characterization of gallium nitride modified with peptides before and after exposure to ionizing radiation in solution.

PubMed

Berg, Nora G; Nolan, Michael W; Paskova, Tania; Ivanisevic, Albena

2014-12-30

An aqueous surface modification of gallium nitride was employed to attach biomolecules to the surface. The modification was a simple two-step process using a single linker molecule and mild temperatures. The presence of the peptide on the surface was confirmed with X-ray photoelectron spectroscopy. Subsequently, the samples were placed in water baths and exposed to ionizing radiation to examine the effects of the radiation on the material in an environment similar to the body. Surface analysis confirmed degradation of the surface of GaN after radiation exposure in water; however, the peptide molecules successfully remained on the surface following exposure to ionizing radiation. We hypothesize that during radiation exposure of the samples, the radiolysis of water produces peroxide and other reactive species on the sample surface. Peroxide exposure promotes the formation of a more stable layer of gallium oxyhydroxide which passivates the surface better than other oxide species.

Meteorite bombardment and dating of planetary surfaces. Thesis - Feb. 1983

NASA Technical Reports Server (NTRS)

Neukum, G.

1984-01-01

Dating by measurement of impact crater frequencies developed in the past years primarily on the basis of the data from the missions to the Moon and Mars. The method allows a good relative dating to be obtained and the moons of Jupiter and Saturn through photographic analyses. A cratering chronology was obtained for the period between the oldest Moon crust (4.3 to 4.4 billion years) to the present time which gives a good absolute dating of any areas of the Moon's surface.

75 FR 21662 - Access to Employee Exposure and Medical Records; Extension of the Office of Management and Budget...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-26

...] Access to Employee Exposure and Medical Records; Extension of the Office of Management and Budget's (OMB... Regulation on Access to Employee Exposure and Medical Records (29 CFR 1910.1020). DATES: Comments must be... operating small businesses, and to reduce to the maximum extent feasible unnecessary duplication of efforts...

76 FR 23809 - Science Advisory Board Staff Office Notification of a Public Meeting of the Clean Air Scientific...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-28

...: Scope and Methods Plan for Welfare Risk and Exposure Assessment (April 2011 Draft). DATES: The CASAC... Ambient Air Quality Standards: Scope and Methods Plan for Health Risk and Exposure Assessment (April 2011), and Ozone National Ambient Air Quality Standards: Scope and Methods Plan for Welfare Risk and Exposure...

Surface dating of bricks, an application of luminescence techniques

NASA Astrophysics Data System (ADS)

Galli, Anna; Martini, Marco; Maspero, Francesco; Panzeri, Laura; Sibilia, Emanuela

2014-05-01

Luminescence techniques are a powerful tool to date archaeological ceramic materials and geological sediments. Thermoluminescence (TL) is widely used for bricks dating to reconstruct the chronology of urban complexes and the development of human cultures. However, it can sometimes be inconclusive, since TL assesses the firing period of bricks, which can be reused, even several centuries later. This problem can be circumvented using a dating technique based on a resetting event different from the last heating. OSL (Optically Stimulated Luminescence) exploits the last light exposition of the brick surface, which resets the light-sensitive electron traps until the surface is definitely shielded by mortar and superimposed bricks. This advanced application (surface dating) has been successfully attempted on rocks, marble and stone artifacts, but not yet on bricks. A recent conservation campaign at the Certosa di Pavia gave the opportunity to sample some bricks belonging to a XVII century collapsed wall, still tied to their mortars. This was an advantageous condition to test this technique, comparing the dating results with precise historical data. This attempt gave satisfactory results, allowing to identify bricks surely reused and to fully confirm that the edification of the perimetral wall occurred at the end of XVII century.

Specific Caleosin/Peroxygenase and Lipoxygenase Activities Are Tissue-Differentially Expressed in Date Palm (Phoenix dactylifera L.) Seedlings and Are Further Induced Following Exposure to the Toxin 2,3,7,8-tetrachlorodibenzo-p-dioxin

PubMed Central

Hanano, Abdulsamie; Almousally, Ibrahem; Shaban, Mouhnad; Rahman, Farzana; Hassan, Mehedi; Murphy, Denis J.

2017-01-01

Two caleosin/peroxygenase isoforms from date palm, Phoenix dactylifera L., PdCLO2 and PdCLO4, were characterized with respect to their tissue expression, subcellular localization, and oxylipin pathway substrate specificities in developing seedlings. Both PdCLO2 and PdCLO4 had peroxygenase activities that peaked at the mid-stage (radicle length of 2.5 cm) of seedling growth and were associated with the lipid droplet (LD) and microsomal fractions. Recombinant PdCLO2 and PdCLO4 proteins heterologously expressed in yeast cells were localized in both LD and microsomal fractions. Each of the purified recombinant proteins exhibited peroxygenase activity but they were catalytically distinct with respect to their specificity and product formation from fatty acid epoxide and hydroxide substrates. We recently showed that date palm CLO genes were upregulated following exposure to the potent toxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (Hanano et al., 2016), and we show here that transcripts of 9- and 13-lipoxygenase (LOX) genes were also induced by TCDD exposure. At the enzyme level, 9-LOX and 13-LOX activities were present in a range of seedling tissues and responded differently to TCDD exposure, as did the 9- and 13-fatty acid hydroperoxide reductase activities. This demonstrates that at least two branches of the oxylipin pathway are involved in responses to the environmental organic toxin, TCDD in date palm. PMID:28111588

Dish concentrators for solar thermal energy - Status and technology development

NASA Technical Reports Server (NTRS)

Jaffe, L. D.

1981-01-01

Comparisons are presented of point-focusing, or 'dish' solar concentrator system features, development status, and performance levels demonstrated to date. In addition to the requirements of good optical efficiency and high geometric concentration ratios, the most important future consideration in solar thermal energy dish concentrator design will be the reduction of installed and lifetime costs, as well as the materials and labor costs of production. It is determined that technology development initiatives are needed in such areas as optical materials, design wind speeds and wind loads, structural configuration and materials resistance to prolonged exposure, and the maintenance of optical surfaces. The testing of complete concentrator systems, with energy-converting receivers and controls, is also necessary. Both reflector and Fresnel lens concentrator systems are considered.

Slip-rate measurements on the Karakorum Fault may imply secular variations in fault motion.

PubMed

Chevalier, M-L; Ryerson, F J; Tapponnier, P; Finkel, R C; Van Der Woerd, J; Haibing, Li; Qing, Liu

2005-01-21

Beryllium-10 surface exposure dating of offset moraines on one branch of the Karakorum Fault west of the Gar basin yields a long-term (140- to 20-thousand-year) right-lateral slip rate of approximately 10.7 +/- 0.7 millimeters per year. This rate is 10 times larger than that inferred from recent InSAR analyses ( approximately 1 +/- 3 millimeters per year) that span approximately 8 years and sample all branches of the fault. The difference in slip-rate determinations suggests that large rate fluctuations may exist over centennial or millennial time scales. Such fluctuations would be consistent with mechanical coupling between the seismogenic, brittle-creep, and ductile shear sections of faults that reach deep into the crust.

Multiple dating approach (14C, U/Th and 36Cl) of tsunami-transported reef-top megaclasts on Bonaire (Leeward Antilles) - potential and current limitations

NASA Astrophysics Data System (ADS)

Rixhon, Gilles; May, Simon Matthias; Engel, Max; Mechernich, Silke; Keulertz, Rebecca; Schroeder-Ritzrau, Andrea; Fohlmeister, Jens; Frank, Norbert; Dunai, Tibor; Brueckner, Helmut

2016-04-01

Coastal hazard assessment depends on reliable information on the magnitude and frequency of past high-energy wave events (EWE: tsunamis, storms). For this purpose onshore sedimentary records represent promising geo-archives for the mid- and late-Holocene EWE history. In comparison to fine-grained sediments which have been extensively studied in the recent past, supralittoral megaclasts are less investigated, essentially due to the difficulties related to the dating of corresponding depositional events, and thus their limited value for inferring the timing of major events. On Bonaire (Leeward Antilles, Caribbean), supratidal coarse-clast deposits form prominent landforms all around the island. Fields of large boulders (up to 150 t) are among the best-studied reef-top megaclasts worldwide. Transport by Holocene tsunamis is assumed at least for the largest boulders (Engel and May, 2012). Although a large dataset of 14C and electron spin resonance (ESR) ages is available for major coral rubble ridges and ramparts, showing some age clusters during the Late Holocene, it is still debated whether these data reflect the timing of major depositional/transport event(s), and how these data sets are biased by reworking of coral fragments. In addition, different processes may be responsible for the deposition of the coral rubble ridges and ramparts (storm) and the solitary megaclasts (tsunami). As an attempt to overcome the current challenges for dating the dislocation of the megaclasts, three distinct dating methods were implemented: (i) 14C dating of boring bivalves (Lithophaga) attached to the boulders; (ii) uranium-series (U/Th) dating of post-depositional, secondary calcitic flowstone at the underside of the boulders; and (iii) surface exposure dating of overturned boulders via 36Cl concentration measurements in corals. The three 14C datings yield age estimates >37 ka, i.e. most probably beyond the applicability of the method, which sheds doubt on the usefulness of this method in the current context. It seems that the bivalves had incorporated the old CaCO3 from the MIS 5.5 mother rock. A U/Th age of the calcitic flowstone points to the Late Holocene period (1.3 ka); it represents a minimum age for boulder transport. Further U/Th dating is in progress. Four coral samples collected from three overturned boulders yielded similar 36Cl concentration measurements, also pointing to a late Holocene dislocation of the clasts. However, it remains unclear whether this concentration cluster mostly results from nuclide accumulation at the "blank" side, subsequent to their overturning during the depositional event, or already from pre-exposure at depth in the MIS 5.5 coral reef platform prior to the EWE. Further analysis is in progress to disentangle the problematic role of inheritance. These preliminary results show the potential and the current limitations of the applied methods for dating the dislocation of supralittoral megaclasts. Reference: Engel, M., May, S.M.: Bonaire's boulder fields revisited: evidence for Holocene tsunami impact on the Leeward Antilles. Quat. Sci. Rev., 54, 126-141, 2012.

Late Pleistocene glacial chronology of the Retezat Mts, Southern Carpathians, using 10Be exposure ages

NASA Astrophysics Data System (ADS)

Ruszkiczay-Rüdiger, Zsófia; Kern, Zoltán; Urdea, Petru; Braucher, Régis; Madarász, Balázs; Schimmelpfennig, Irene

2015-04-01

Our knowledge on the timing of glacial advances in the Southern Carpathians is limited. Recently, some attempts have been made to develop an improved temporal framework for the glaciations of the region using cosmogenic 10Be exposure dating. However, glacial chronology of the Romanian Carpathians remains contradictory. E.g. the timing of the maximum ice advance appears to be asynchronous within the area and also with other dated glacial events in Europe. Main objective of our study is to utilize cosmogenic in situ produced 10Be dating to disentangle the contradictions of the Southern Carpathian Late Pleistocene glacial chronology. Firstly, previously published 10Be data are recalculated in accordance with the new half-life, standardization and production rate of 10Be. The recalculated 10Be exposure ages of the second largest (M2) moraines in the Retezat Mts. appear to be ca. 19-24% older than exposure ages calculated by Reuther et al. (2007, Quat. Int. 164-165, 151-169). This contradicts the earlier conclusions suggesting post LGM age of M2 glacial advance and suggests that M2 moraines can be connected to the end of the LGM with final stabilization possibly at the beginning of the Late Glacial. We emphasize that it is ambiguous to correlate directly the exposure-dated glacier chronologies with millennial scale climate changes due to uncertainties in sample collection and in computation of exposure ages from measured nuclide concentrations. New 10Be samples were collected in order to determine the 10Be exposure age of moraines outside the most prominent generation (M2) including the largest and oldest moraine (M1) and the landforms connected to the smallest ice advances (M4), which remained undated so far. The new exposure ages of M2 moraines are well in harmony with the recalculated ages of Reuther at al. (2007). 10Be exposure age of boulders on the smallest moraine suggest that the last glaciers disappeared in the area during the Late Glacial, indicating no glaciation during the Younger Dryas and Holocene. Previous works, based on geomorphologic analogies and pedological properties suggested that the M1 ice advance was older than LGM, and possibly occurred during the MIS4. Our 10Be exposure dating provided LGM ages for boulders on the M1 side moraine. It is question of further research whether these ages show the time when the glacier abandoned the moraine or they only indicate an LGM erosional event affecting an older moraine. If we accept the LGM age of maximum ice extent (M1), our 10Be exposure age data enables the calculation of a mean glacier retreat rate of 1.3 m/a for the period between M1 and M4 (21.4 to 13.6ka). Alternatively, considering only the oldest 10Be exposure age of the M2 moraine, the M2 to M4 (20.2-13.6ka) glacier retreat rate was slightly lower: 1.1 m/a. Our research was supported by the OTKA PD83610, by the MTA-CNRS cooperation (NKM-96/2014), by the Bolyai Scholarship, and by the 'Lendület' program of the HAS (LP2012-27/2012). The 10Be measurements were performed at the ASTER AMS national facility (CEREGE, Aix en Provence, France).

Terrestrial cosmogenic surface exposure dating of glacial and associated landforms in the Ruby Mountains-East Humboldt Range of central Nevada and along the northeastern flank of the Sierra Nevada

DOE PAGES

Wesnousky, Steven G.; Briggs, Richard W.; Caffee, Marc W.; ...

2016-05-07

Deposits near Lamoille in the Ruby Mountains-East Humboldt Range of central Nevada and at Woodfords on the eastern edge of the Sierra Nevada each record two distinct glacial advances. In this paper, we compare independent assessments of terrestrial cosmogenic nuclide (TCN) surface exposure ages for glacial deposits that we have determined to those obtained by others at the two sites. At each site, TCN ages of boulders on moraines of the younger advance are between 15 and 30 ka and may be associated with marine oxygen isotope stage (MIS) 2. At Woodfords, TCN ages of boulders on the moraine ofmore » the older advance are younger than ~ 60 ka and possibly formed during MIS 4, whereas boulders on the correlative outwash surface show ages approaching 140 ka (~ MIS 6). The TCN ages of boulders on older glacial moraine at Woodfords thus appear to severely underestimate the true age of the glacial advance responsible for the deposit. The same is possibly true at Lamoille where clasts sampled from the moraine of the oldest advance have ages ranging between 20 and 40 ka with a single outlier age of ~ 80 ka. The underestimations are attributed to the degradation and denudation of older moraine crests. Noting that boulder ages on the older advances at each site overlap significantly with MIS 2. Finally, we speculate that erosion of the older moraines has been episodic, with a pulse of denudation accompanying the inception of MIS 2 glaciation.« less

Terrestrial cosmogenic surface exposure dating of glacial and associated landforms in the Ruby Mountains-East Humboldt Range of central Nevada and along the northeastern flank of the Sierra Nevada

USGS Publications Warehouse

Wesnousky, Steven G.; Briggs, Richard; Caffee, Marc W.; Ryerson, Rick J.; Finkel, Robert C.; Owen, Lewis A.

2016-01-01

Deposits near Lamoille in the Ruby Mountains-East Humboldt Range of central Nevada and at Woodfords on the eastern edge of the Sierra Nevada each record two distinct glacial advances. We compare independent assessments of terrestrial cosmogenic nuclide (TCN) surface exposure ages for glacial deposits that we have determined to those obtained by others at the two sites. At each site, TCN ages of boulders on moraines of the younger advance are between 15 and 30 ka and may be associated with marine oxygen isotope stage (MIS) 2. At Woodfords, TCN ages of boulders on the moraine of the older advance are younger than ~ 60 ka and possibly formed during MIS 4, whereas boulders on the correlative outwash surface show ages approaching 140 ka (~ MIS 6). The TCN ages of boulders on older glacial moraine at Woodfords thus appear to severely underestimate the true age of the glacial advance responsible for the deposit. The same is possibly true at Lamoille where clasts sampled from the moraine of the oldest advance have ages ranging between 20 and 40 ka with a single outlier age of ~ 80 ka. The underestimations are attributed to the degradation and denudation of older moraine crests. Noting that boulder ages on the older advances at each site overlap significantly with MIS 2. We speculate that erosion of the older moraines has been episodic, with a pulse of denudation accompanying the inception of MIS 2 glaciation.

Paleoearthquake recurrence on the East Paradise fault zone, metropolitan Albuquerque, New Mexico

USGS Publications Warehouse

Personius, Stephen F.; Mahan, Shannon

2000-01-01

A fortuitous exposure of the East Paradise fault zone near Arroyo de las Calabacillas has helped us determine a post-middle Pleistocene history for a long-forgotten Quaternary fault in the City of Albuquerque, New Mexico. Mapping of two exposures of the fault zone allowed us to measure a total vertical offset of 2.75 m across middle Pleistocene fluvial and eolian deposits and to estimate individual surface-faulting events of about 1, 0.5, and 1.25 m. These measurements and several thermoluminescence ages allow us to calculate a long-term average slip rate of 0.01 ± 0.001 mm/yr and date two surface-faulting events to 208 ± 25 ka and 75 ± 7 ka. The youngest event probably occurred in the late Pleistocene, sometime after 75 ± 7 ka. These data yield a single recurrence interval of 133 ± 26 ka and an average recurrence interval of 90 ± 10 ka. However, recurrence intervals are highly variable because the two youngest events occurred in less than 75 ka. Offsets of 0.5-1.25 m and a fault length of 13-20 km indicate that surface-rupturing paleoearthquakes on the East Paradise fault zone had probable Ms or Mw magnitudes of 6.8-7.0. Although recurrence intervals are long on the East Paradise fault zone, these data are significant because they represent some of the first published slip rate, paleoearthquake magnitude, and recurrence information for any of the numerous Quaternary faults in the rapidly growing Albuquerque-Rio Rancho metropolitan area.

36Chlorine exposure dating of a terminal moraine in the Galicica Mountains, Macedonia

NASA Astrophysics Data System (ADS)

Gromig, R.; Mechernich, S.; Ribolini, A.; Dunai, T. J.; Wagner, B.

2015-12-01

The glaciation history of the Balkan Peninsula is subject of research since the late 19th century. To date, only a few moraines on the Balkan Peninsula are dated, mainly using 10Be exposure dating applied on quartz bearing rocks. Since large parts of the Balkan Peninsula mountains are composed of carbonatic rocks, absolute age dating is restricted to 36Cl exposure dating, which, to date, was not conducted in this region yet. So far, an absolute chronological control in limestone-dominated areas is limited to U-series minimum ages of calcitic cements. In order to obtain more information about the timing of the glaciation history on the Balkan Peninsula, we investigated a terminal moraine in a NNE-facing cirque in the Galicica Mountains (40°56´N, 20°49´E) in the Former Yugoslav Republic of Macedonia. The cirque comprises a series of nested moraine ridges at the base of the cirque wall, with the largest one being sampled. Samples from five limestone boulders in crest position (≈ 2050 m a.s.l.) were taken and pre-treated for AMS measurement at the University of Cologne. Three preliminary ages point to a moraine formation in the course of a late Pleistocene glaciation, either Last Glacial Maximum or Younger Dryas. The data were discussed concerning corrections for topographic shielding, snow cover, inheritance, and erosion. However, five AMS re-measurements are currently in progress in order to refine the correlation of the moraine formation to a specific glacial period. The resulting ages will be compared to sediments of the adjacent Lakes Ohrid and Prespa, which represent valuable climatic and environmental archives. Several studies on these sediments were carried out in order to reconstruct relative changes in temperature and moisture availability. Moreover, the inferred moraine formation ages will be compared to glaciation reconstructions of other mountainous regions on the Balkan Peninsula to improve the knowledge on past climatic conditions.

K/Ar dating of lunar soils. II

NASA Technical Reports Server (NTRS)

Alexander, E. C., Jr.; Bates, A.; Coscio, M. R., Jr.; Dragon, J. C.; Murthy, V. R.; Pepin, R. O.; Venkatesan, T. R.

1976-01-01

An attempt is made to identify those K/Ar techniques which extract the most reliable chronological information from lunar soils and to define the situations in which the best data are obtainable. Results are presented for determinations of the exposure and K/Ar ages of five lunar soil samples, which were performed by applying correlation techniques for a two-component argon structure to stepwise-heated and neutron-irradiated aliquots of grain-sized separates. It is found that ages deduced from Ar-40/surface-correlated Ar-36 vs K-40/surface-correlated Ar-36 and analogous plots of data from grain-sized separates appear to be the best available K/Ar ages of submature to mature lunar soils, that ages deduced from Ar-40 vs Ar-36 and analogous plots which assume a uniform K content can be significantly in error, and that stepwise-heating (Ar-40)-(Ar-39) experiments yield useful information only for simple immature soils where the K-Ar systematics are dominated by a single component.

The application of remotely sensed data to pedologic and geomorphic mapping on alluvial fan and playa surfaces in Saline Valley, California

NASA Technical Reports Server (NTRS)

Miller, D. A.; Petersen, G. W.; Kahle, A. B.

1986-01-01

Arid and semiarid regions yield excellent opportunities for the study of pedologic and geomorphic processes. The dominance of rock and soil exposure over vegetation not only provides the ground observer with observational possibilities but also affords good opportunities for measurement by aircraft and satellite remote sensor devices. Previous studies conducted in the area of pedologic and geomorphic mapping in arid regions with remotely sensed data have utilized information obtained in the visible to near-infrared portion of the spectrum. Thermal Infrared Multispectral Scanner (TIMS) and Thematic Mapping (TM) data collected in 1984 are being used in comjunction with maps compiled during a Bureau of Land Management (BLM) soil survey to aid in a detailed mapping of alluvial fan and playa surfaces within the valley. The results from this study may yield valuable information concerning the application of thermal data and thermal/visible data combinations to the problem of dating pedologic and geomorphic features in arid regions.

Just the right age: well-clustered exposure ages from a global glacial 10Be compilation

NASA Astrophysics Data System (ADS)

Heyman, Jakob; Margold, Martin

2017-04-01

Cosmogenic exposure dating has been used extensively for defining glacial chronologies, both in ice sheet and alpine settings, and the global set of published ages today reaches well beyond 10,000 samples. Over the last few years, a number of important developments have improved the measurements (with well-defined AMS standards) and exposure age calculations (with updated data and methods for calculating production rates), in the best case enabling high precision dating of past glacial events. A remaining problem, however, is the fact that a large portion of all dated samples have been affected by prior and/or incomplete exposure, yielding erroneous exposure ages under the standard assumptions. One way to address this issue is to only use exposure ages that can be confidently considered as unaffected by prior/incomplete exposure, such as groups of samples with statistically identical ages. Here we use objective statistical criteria to identify groups of well-clustered exposure ages from the global glacial "expage" 10Be compilation. Out of ˜1700 groups with at least 3 individual samples ˜30% are well-clustered, increasing to ˜45% if allowing outlier rejection of a maximum of 1/3 of the samples (still requiring a minimum of 3 well-clustered ages). The dataset of well-clustered ages is heavily dominated by ages <30 ka, showing that well-defined cosmogenic chronologies primarily exist for the last glaciation. We observe a large-scale global synchronicity in the timing of the last deglaciation from ˜20 to 10 ka. There is also a general correlation between the timing of deglaciation and latitude (or size of the individual ice mass), with earlier deglaciation in lower latitudes and later deglaciation towards the poles. Grouping the data into regions and comparing with available paleoclimate data we can start to untangle regional differences in the last deglaciation and the climate events controlling the ice mass loss. The extensive dataset and the statistical analysis enables an unprecedented global view on the last deglaciation.

Comparison of gestational dating methods and implications for exposure-outcome associations: an example with PM2.5 and preterm birth.

PubMed

Rappazzo, Kristen M; Lobdell, Danelle T; Messer, Lynne C; Poole, Charles; Daniels, Julie L

2017-02-01

Estimating gestational age is usually based on date of last menstrual period (LMP) or clinical estimation (CE); both approaches introduce potential bias. Differences in methods of estimation may lead to misclassification and inconsistencies in risk estimates, particularly if exposure assignment is also gestation-dependent. This paper examines a 'what-if' scenario in which alternative methods are used and attempts to elucidate how method choice affects observed results. We constructed two 20-week gestational age cohorts of pregnancies between 2000 and 2005 (New Jersey, Pennsylvania, Ohio, USA) using live birth certificates: one defined preterm birth (PTB) status using CE and one using LMP. Within these, we estimated risk for 4 categories of preterm birth (PTBs per 10 6 pregnancies) and risk differences (RD (95% CIs)) associated with exposure to particulate matter (PM 2.5 ). More births were classified preterm using LMP (16%) compared with CE (8%). RD divergences increased between cohorts as exposure period approached delivery. Among births between 28 and 31 weeks, week 7 PM 2.5 exposure conveyed RDs of 44 (21 to 67) for CE and 50 (18 to 82) for LMP populations, while week 24 exposure conveyed RDs of 33 (11 to 56) and -20 (-50 to 10), respectively. Different results from analyses restricted to births with both CE and LMP are most likely due to differences in dating methods rather than selection issues. Results are sensitive to choice of gestational age estimation, though degree of sensitivity can vary by exposure timing. When both outcome and exposure depend on estimate of gestational age, awareness of nuances in the method used for estimation is critical. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Using age of colonizing douglas-fir for the dating of young geomorphic surfaces: a case study

USGS Publications Warehouse

Pierson, Thomas C.

2013-01-01

Dating of many types of young (<500 year), dynamic, geomorphic landforms (e.g. mass-movement erosional tracks and deposits, alluvial terraces, flood plains, etc.) for purposes of hazard assessment and mitigation commonly requires greater dating precision than is available through radiocarbon dating or other methods. Ages of trees growing on landform surfaces have been used in a number of studies to estimate the time of landform creation or surface clearing, but the time lag between surface formation or disturbance and the reestablishment of trees can vary from 1 to more than 200 years (Desloges and Ryder 1990; Frenzen et al. 1988, 2005; Larsen and Bliss 1998; McCarthy and Luckman 1993; Sigafoos and Hendricks 1969; Winter et al. 2002). Appropriate lag times for selected tree species and for particular climatic and altitudinal ranges must be determined for the method to be useful.

Project Date SMART: a Dating Violence (DV) and Sexual Risk Prevention Program for Adolescent Girls with Prior DV Exposure.

PubMed

Rizzo, Christie J; Joppa, Meredith; Barker, David; Collibee, Charlene; Zlotnick, Caron; Brown, Larry K

2018-05-01

This study assessed the initial feasibility, acceptability, and efficacy of an intervention aimed at reducing dating violence and sexual risk behavior in a sample of adolescent girls (ages 14-17) with prior exposure to physical dating violence (DV). One hundred and nine girls were randomly assigned to Date SMART (Skills to Manage Aggression in Relationships for Teens) or a Knowledge-only (KO) comparison group. Both intervention arms consisted of six, weekly 2-h sessions and one "booster" session 6 weeks later. Based on principles of cognitive behavioral therapy, the Date SMART intervention was designed to target common underlying skills deficits linked to both DV and sexual risk behavior in adolescent females: depression, self-regulation deficits, and interpersonal skills deficits. Assessments were administered at four time points (baseline, 3, 6, and 9 months). The Date SMART group was effective as reducing sexual DV involvement across the 9-month follow-up period. Both groups evidenced clinically meaningful reductions in physical, emotional, and digital DV involvement, total time in dating relationships, as well as reductions in depression. Findings indicate that delivering a DV and sexual risk prevention intervention to DV-affected adolescent girls is feasible and well-received. Furthermore, a skills-based approach that addresses the co-occurrence of DV and sexual risk behavior may be particularly useful for promoting reductions of sexual DV among high-risk adolescent girls. A future, large-scale trial with an inactive comparison condition is needed to evaluate the efficacy of Date SMART further. Clinical Trials, NCT01326195, and http://www.clinicaltrials.gov.

Carbonaceous particulate matter on the lung surface from adults living in São Paulo, Brazil.

PubMed

Padovan, Michele Galhardoni; Whitehouse, Abigail; Gouveia, Nelson; Habermann, Mateus; Grigg, Jonathan

2017-01-01

We therefore sought to identify the exposures associated with lung surface in long-term residents of São Paulo, Brazil. Lung surface carbon were analyzed in 72 autopsy specimens by image analysis. Smoking history, measured PM10 nearest to the home, distance to main road, and distance-weighted traffic density were used as exposure variables. Data are summarized as median (IQR), and compared by Mann Whitney Test, with correlations done by Spearman's correlation. There was no association between lung surface and age or gender. There was no statistically significant association in lung surface between smokers and non-smokers 6.74 cm2 (3.47 to 10.02) versus 5.20cm2 (2.29 to 7.54), and there was no significant association between lung surface carbon and exposure to environmental PM and markers of traffic exposure. We did not find a statistically significant association between lung surface and smokers and non-smokers, and no statistically significant association between lung surface carbon and environmental exposure variables. These results suggest that lung surface carbon in long-term residents of São Paulo may predominately be from environmental PM, but the most appropriate environmental exposure marker remains unclear.

Nanoscale Compositional Relations in Lunar Rock Patina: Deciphering Sources for Patina Components on an Apollo 17 Station 6 Boulder

NASA Technical Reports Server (NTRS)

Christoffersen, R.; Noble, S. K.; Keller, L. P.

2014-01-01

Space weathering on the Moon and other airless bodies modifies the surfaces of regolith grains as well as the space-exposed surfaces of larger rocks and boulders. As space weathering witness plates, rocks and boulders are distinguished from regolith grains based on their ability to persist as physically intact substrates over longer time scales before being disaggregated by impact processes. Because lunar surfaces, including exposed rocks, quickly develop an optically thick layer of patina, it is important to understand the compositional relationship between patinas and their underlying rock substrates, particularly to support remote-sensing of rocky lunar terrains. Based on analytical TEM techniques, supported by focused ion beam (FIB) cross-sectioning, we have begun to systematize the multi-layer microstructural complexity of patinas on rock samples with a range of space exposure histories. Our on-going work has particularly focused on lunar rock 76015, both because it has a long (approx. 22 my) exposure history, and because its surface was exposed to patina development approximately 1 m off the regolith surface on a boulder in the Apollo 17 Station 6 boulder field. Potential sources for the 76015 patina therefore include impact-melted and vaporized material derived from the local rock substrate, as well as from the mix of large boulders and regolith in the Station 6 area. While similar, there are differences in the mineralogy and chemistry of the rocks and regolith at Station 6. We were interested to see if these, or other sources, could be distinguished in the average composition, as well as the compositional nanostratigraphy of the 76015 patina. To date we have acquired a total of 9 TEM FIB cross-sections from the 76015 patina, giving us reasonable confidence of being able to arrive at an integrated average for the patina major element composition based on analytical TEM methods.

The effect of past antibiotic exposure on diabetes risk

PubMed Central

Boursi, Ben; Mamtani, Ronac; Haynes, Kevin; Yang, Yu-Xiao

2015-01-01

Objective Gut microbiota influence metabolic pathways relevant to the pathogenesis of obesity, insulin-resistance and diabetes. Antibiotic therapy can alter the microbiota and is commonly used in western countries. We sought to evaluate whether past antibiotic exposure increases diabetes risk. Research design and methods We conducted a nested case-control study using a large population-based database from the United Kingdom (UK). Cases were defined as those with incident diagnosis of diabetes. For every case, 4 eligible controls matched on age, sex, practice-site, and duration of follow-up before index-date were selected using incidence-density sampling. Exposure of interest was antibiotic therapy >1 year before index-date. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using conditional logistic regression. The risk was adjusted for body mass index (BMI), smoking, last glucose level and number of infections before index-date, as well as past medical history of coronary artery disease and hyperlipidemia. Results The study included 208,002 diabetic cases and 815,576 matched controls. Exposure to a single antibiotic prescription was not associated with higher adjusted diabetes risk. Treatment with 2–5 antibiotic courses was associated with increase in diabetic risk for penicillin, cephalosporins, macrolides and quinolones with adjusted OR ranging from 1.08 (95%CI 1.05–1.11) for penicillin to 1.15 (95%CI 1.08–1.23) for quinolones. The risk increased with the number of antibiotic courses and reached 1.37 (95%CI 1.19–1.58) for >5 courses of quinolones. There was no association between exposure to anti-virals and anti-fungals and diabetes risk. Conclusions Exposure to certain antibiotic groups increases diabetes risk. PMID:25805893

Male fertility following occupational exposure to dichlorodiphenyltrichloroethane (DDT).

PubMed

Campagna, Marcello; Satta, Giannina; Fadda, Domenica; Pili, Sergio; Cocco, Pierluigi

2015-04-01

The inconsistent epidemiological results of the endocrine disrupting effects of DDT fuel a harsh debate on its global ban. We tested the hypothesis that occupational exposure to dichloro-diphenyl-trichloroethane (DDT) causes impairment in male fertility in a cohort of DDT exposed workers, in Sardinia, Italy. We accessed official records on date of marriage and date of birth of the first child to estimate time to pregnancy (TTP) in the spouses of 1223 workers employed in a 1946-1950 anti-malarial campaign. The TTP calculation was censored at the 13th month after date of marriage. We used a modified Cox's proportional hazard model to calculate the fecundability ratio (FR) by job, by cumulative exposure to DDT, and by time window in relation to the anti-malarial operations, adjusting by paternal age at marriage. Among the spouses of DDT applicators, fecundability did not vary during DDT use (FR=1.22, 95% CI 0.84-1.77) nor in the following decade (FR=1.01, 95% CI 0.67-1.50) with reference to the prior years. A significant increase occurred among the unexposed and the less exposed sub-cohorts, which generated a non-significantly reduced FR among the DDT applicator sub-cohort with reference to the unexposed following exposure. We did not find evidence of an impairment in male fertility following heavy occupational exposure to DDT. However, although fecundability was highest among the spouses of the DDT applicators in the years prior to the anti-malarial campaign, we cannot exclude that DDT exposure prevented an increase parallel to that observed among the unexposed and the less exposed sub-cohorts. Copyright © 2015. Published by Elsevier Ltd.

Considerations for estimating microbial environmental data concentrations collected from a field setting

PubMed Central

Silvestri, Erin E; Yund, Cynthia; Taft, Sarah; Bowling, Charlena Yoder; Chappie, Daniel; Garrahan, Kevin; Brady-Roberts, Eletha; Stone, Harry; Nichols, Tonya L

2017-01-01

In the event of an indoor release of an environmentally persistent microbial pathogen such as Bacillus anthracis, the potential for human exposure will be considered when remedial decisions are made. Microbial site characterization and clearance sampling data collected in the field might be used to estimate exposure. However, there are many challenges associated with estimating environmental concentrations of B. anthracis or other spore-forming organisms after such an event before being able to estimate exposure. These challenges include: (1) collecting environmental field samples that are adequate for the intended purpose, (2) conducting laboratory analyses and selecting the reporting format needed for the laboratory data, and (3) analyzing and interpreting the data using appropriate statistical techniques. This paper summarizes some key challenges faced in collecting, analyzing, and interpreting microbial field data from a contaminated site. Although the paper was written with considerations for B. anthracis contamination, it may also be applicable to other bacterial agents. It explores the implications and limitations of using field data for determining environmental concentrations both before and after decontamination. Several findings were of interest. First, to date, the only validated surface/sampling device combinations are swabs and sponge-sticks on stainless steel surfaces, thus limiting availability of quantitative analytical results which could be used for statistical analysis. Second, agreement needs to be reached with the analytical laboratory on the definition of the countable range and on reporting of data below the limit of quantitation. Finally, the distribution of the microbial field data and statistical methods needed for a particular data set could vary depending on these data that were collected, and guidance is needed on appropriate statistical software for handling microbial data. Further, research is needed to develop better methods to estimate human exposure from pathogens using environmental data collected from a field setting. PMID:26883476

Comparison of gestational dating methods and implications for exposure-outcome associations: an example with PM2.5 and preterm birth

EPA Science Inventory

OBJECTIVES: Estimating gestational age is usually based on date of last menstrual period (LMP) or clinical estimation (CE); both approaches introduce potential bias. Differences in methods of estimation may lead to misclassificat ion and inconsistencies in risk estimates, particu...

Youth Experiences of Family Violence and Teen Dating Violence Perpetration: Cognitive and Emotional Mediators

ERIC Educational Resources Information Center

Jouriles, Ernest N.; McDonald, Renee; Mueller, Victoria; Grych, John H.

2012-01-01

This article describes a conceptual model of cognitive and emotional processes proposed to mediate the relation between youth exposure to family violence and teen dating violence perpetration. Explicit beliefs about violence, internal knowledge structures, and executive functioning are hypothesized as cognitive mediators, and their potential…

Victimization during Childhood and Revictimization in Dating Relationships in Adolescent Girls

ERIC Educational Resources Information Center

Gagne, Marie-Helene; Lavoie, Francine; Hebert, Martine

2005-01-01

Objective: Various experiences with violence during childhood and adolescence (parental violence, exposure to marital violence, sexual abuse within and outside the family, sexual harassment at school, community violence, involvement with violent or victimized peers, and previous dating violence) are examined as potential risk factors for…

Chronological and geomorphological investigation of fossil debris-covered glaciers in relation to deglaciation processes: A case study in the Sierra de La Demanda, northern Spain

NASA Astrophysics Data System (ADS)

Fernández-Fernández, José M.; Palacios, David; García-Ruiz, José M.; Andrés, Nuria; Schimmelpfennig, Irene; Gómez-Villar, Amelia; Santos-González, Javier; Álvarez-Martínez, Javier; Arnáez, José; Úbeda, José; Léanni, Laëtitia; Aumaître, Georges; Bourlès, Didier; Keddadouche, Karim; Aster Team

2017-08-01

In this study, fossil debris-covered glaciers are investigated and dated in the Sierra de la Demanda, northern Spain. They are located in glacial valleys of approximately 1 km in length, where several moraines represent distinct phases of the deglaciation period. Several boulders in the moraines and fossil debris-covered glaciers were selected for analysis of 10Be surface exposure dating. A minimum age of 17.8 ± 2.2 ka was obtained for the outermost moraine in the San Lorenzo cirque, and was attributed to the global Last Glacial Maximum (LGM) or earlier glacial stages, based on deglaciation dates determined in other mountain areas of northern Spain. The youngest moraines were dated to approximately 16.7 ± 1.4 ka, and hence correspond to the GS-2a stadial (Oldest Dryas). Given that the debris-covered glaciers fossilize intermediate moraines, it was deduced that they developed between the LGM and the Oldest Dryas, coinciding with a period of extensive deglaciation. During this deglaciation phase, the cirque headwalls likely discharged large quantities of boulders and blocks that covered the residual ice masses. The resulting debris-covered glaciers evolved slowly because the debris mantle preserved the ice core from rapid ablation, and consequently they remained active until the end of the Late Glacial or the beginning of the Holocene (for the San Lorenzo cirque) and the Holocene Thermal Maximum (for the Mencilla cirque). The north-facing part of the Mencilla cirque ensured longer preservation of the ice core.

Development of an objective dose distribution analysis method for OSL dating and pilot studies for planetary applications

NASA Astrophysics Data System (ADS)

Lepper, Kenneth Errol

Scope and method of study. Part I: In its simplest expression a luminescence age is the natural absorbed radiation dose (De) divided by the in-situ dose rate. The experimental techniques of Optically Stimulated Luminescence (OSL) dating have evolved to the point were hundreds of Des, and therefore depositional ages can be quickly and conveniently determined for a single sediment sample. The first major objective of this research was to develop an objective analysis method for analyzing dose distribution data and selecting an age-representative dose (Dp). The analytical method was developed based on dose data sets collected from 3 eolian and 3 fluvial sediment samples from Central Oklahoma. Findings and conclusions. Part I: An objective method of presenting the dose distribution data, and a mathematically rigorous means of determining the Dp, as well as a statistically meaningful definition of the uncertainty in Dp have been proposed. The concept of experimental error deconvolution was introduced. In addition a set of distribution shape parameters to facilitate comparison among samples have been defined. These analytical techniques hold the potential to greatly enhance the accuracy and utility of OSL dating for young fluvial sediments. Scope and method of study. Part II: The second major objective of this research was to propose the application of luminescence dating to sediments on Mars. A set of fundamental luminescence dating properties was evaluated for a martian surface materials analog and a polar deposit contextual analog. Findings and conclusions. Part II: The luminescence signals measured from the analogs were found to have a wide dynamic dose response range with no unusual or prohibitive short-term instabilities and were readily reset by exposure to sunlight. These properties form a stable base for continued investigations toward the development of luminescence dating instruments and procedures for Mars.

Deglacial history of the Pensacola Mountains, Antarctica from glacial geomorphology and cosmogenic nuclide surface exposure dating

NASA Astrophysics Data System (ADS)

Bentley, M. J.; Hein, A. S.; Sugden, D. E.; Whitehouse, P. L.; Shanks, R.; Xu, S.; Freeman, S. P. H. T.

2017-02-01

The retreat history of the Antarctic Ice Sheet is important for understanding rapid deglaciation, as well as to constrain numerical ice sheet models and ice loading models required for glacial isostatic adjustment modelling. There is particular debate about the extent of grounded ice in the Weddell Sea embayment at the Last Glacial Maximum, and its subsequent deglacial history. Here we provide a new dataset of geomorphological observations and cosmogenic nuclide surface exposure ages of erratic samples that constrain the deglacial history of the Pensacola Mountains, adjacent to the present day Foundation Ice Stream and Academy Glacier in the southern Weddell Sea embayment. We show there is evidence of at least two glaciations, the first of which was relatively old and warm-based, and a more recent cold-based glaciation. During the most recent glaciation ice thickened by at least 450 m in the Williams Hills and at least 380 m on Mt Bragg. Progressive thinning from these sites was well underway by 10 ka BP and ice reached present levels by 2.5 ka BP, and is broadly similar to the relatively modest thinning histories in the southern Ellsworth Mountains. The thinning history is consistent with, but does not mandate, a Late Holocene retreat of the grounding line to a smaller-than-present configuration, as has been recently hypothesized based on ice sheet and glacial isostatic modelling. The data also show that clasts with complex exposure histories are pervasive and that clast recycling is highly site-dependent. These new data provide constraints on a reconstruction of the retreat history of the formerly-expanded Foundation Ice Stream, derived using a numerical flowband model.

Food grade titanium dioxide disrupts intestinal brush border microvilli in vitro independent of sedimentation.

PubMed

Faust, James J; Doudrick, Kyle; Yang, Yu; Westerhoff, Paul; Capco, David G

2014-06-01

Bulk- and nano-scale titanium dioxide (TiO2) has found use in human food products for controlling color, texture, and moisture. Once ingested, and because of their small size, nano-scale TiO2 can interact with a number of epithelia that line the human gastrointestinal tract. One such epithelium responsible for nutrient absorption is the small intestine, whose constituent cells contain microvilli to increase the total surface area of the gut. Using a combination of scanning and transmission electron microscopy it was found that food grade TiO2 (E171 food additive coded) included ∼25% of the TiO2 as nanoparticles (NPs; <100 nm), and disrupted the normal organization of the microvilli as a consequence of TiO2 sedimentation. It was found that TiO2 isolated from the candy coating of chewing gum and a commercially available TiO2 food grade additive samples were of the anatase crystal structure. Exposure to food grade TiO2 additives, containing nanoparticles, at the lowest concentration tested within this experimental paradigm to date at 350 ng/mL (i.e., 100 ng/cm(2) cell surface area) resulted in disruption of the brush border. Through the use of two independent techniques to remove the effects of gravity, and subsequent TiO2 sedimentation, it was found that disruption of the microvilli was independent of sedimentation. These data indicate that food grade TiO2 exposure resulted in the loss of microvilli from the Caco-2BBe1 cell system due to a biological response, and not simply a physical artifact of in vitro exposure.

Overview on association of different types of leukemias with radiation exposure.

PubMed

Gluzman, D F; Sklyarenko, L M; Zavelevich, M P; Koval, S V; Ivanivska, T S; Rodionova, N K

2015-06-01

Exposure to ionizing radiation is associated with increasing risk of various types of hematological malignancies. The results of major studies on association of leukemias and radiation exposure of large populations in Japan and in Ukraine are analyzed. The patterns of different types of leukemia in 295 Chernobyl clean-up workers diagnosed according to the criteria of up-to-date World Health Organization classification within 10-25 years following Chernobyl catastrophe are summarized. In fact, a broad spectrum of radiation-related hematological malignancies has been revealed both in Life Span Study in Japan and in study of Chernobyl clean-up workers in Ukraine. The importance of the precise diagnosis of tumors of hematopoietic and lymphoid tissues according to up-to-date classifications for elucidating the role of radiation as a causative factor of leukemias is emphasized. Such studies are of high importance since according to the recent findings, radiation-associated excess risks of several types of leukemias seem to persist throughout the follow-up period up to 55 years after the radiation exposure.

Copper toxicity and date palm (Phoenix dactylifera) seedling tolerance: Monitoring of related biomarkers.

PubMed

Chaâbene, Zayneb; Hakim, Imen Rekik; Rorat, Agnieszka; Elleuch, Amine; Mejdoub, Hafedh; Vandenbulcke, Franck

2018-03-01

Date palm (Phoenix dactylifera) seeds were exposed to different copper (Cu) solutions to examine plant stress responses. Low Cu concentrations (0.02 and 0.2 mM) caused an increase of seed germination, whereas higher Cu amounts (2 mM) significantly inhibited seed germination, delayed hypocotyl elongation, increased seedling mortality, and reduced the germination index by more than 90%. Metal-related toxicity symptoms appeared after 15 d of 2 mM of Cu exposure. Biochemical activities such as amylase activity and redox balance elements were examined to study the relationship between external Cu amount and internal plant response. The present study showed that amylolytic activity was dose- and time-dependent. Likewise, H 2 O 2 production increased after exposure to Cu, which was correlated with thiobarbituric acid reactive substance (TBARS) accumulation. Furthermore at low Cu concentrations, superoxide dismutase (SOD) and catalase (CAT) activities increased, suggesting that date palm seed stimulated its metal homeostasis networks. However, the highest cupric ion amounts increased cell oxidant accumulation and reduced enzyme production. Gene expression level measures of P. dactylifera phytochelatin synthase (Pdpcs) and P. dactylifera metallothionein (Pdmt) encoding genes have been carried out to investigate the implication of PdPCS and PdMT proteins in Cu homeostasis and/or its sequestration. Phoenix dactylifera metallothionein induction reached a peak after 30 d of exposure to 0.2 mM of Cu. However, it was down-regulated in plants exposed to higher Cu concentrations. In the same conditions, Pdpcs was overexpressed during 1 mo of exposure before it decreased thereafter. These observations provide a new insight into date palm cell response to Cu, a metal that can be toxic but that is also an essential element. Environ Toxicol Chem 2018;37:797-806. © 2017 SETAC. © 2017 SETAC.

The timing and cause of glacial activity during the last glacial in central Tibet based on 10Be surface exposure dating east of Mount Jaggang, the Xainza range

NASA Astrophysics Data System (ADS)

Dong, Guocheng; Zhou, Weijian; Yi, Chaolu; Fu, Yunchong; Zhang, Li; Li, Ming

2018-04-01

Mountain glaciers are sensitive to climate change, and can provide valuable information for inferring former climates on the Tibetan Plateau (TP). The increasing glacial chronologies indicate that the timing of the local Last Glacial Maximum (LGM) recorded across the TP is asynchronous, implying different local influences of the mid-latitude westerlies and Asian Summer Monsoon in triggering glacier advances. However, the well-dated sites are still too few, especially in the transition zone between regions controlled by the two climate systems. Here we present detailed last glacial chronologies for the Mount Jaggang area, in the Xainza range, central Tibet, with forty-three apparent 10Be exposure-ages ranging from 12.4 ± 0.8 ka to 61.9 ± 3.8 ka. These exposure-ages indicate that at least seven glacial episodes occurred during the last glacial cycle east of Mount Jaggang. These include: a local LGM that occurred at ∼61.9 ± 3.8 ka, possibly corresponding to Marine Isotope Stage 4 (MIS 4); subsequent glacial advances at ∼43.2 ± 2.6 ka and ∼35.1 ± 2.1 ka during MIS 3; one glacial re-advance/standstill at MIS3/2 transition (∼29.8 ± 1.8 ka); and three glacial re-advances/standstills that occurred following MIS 3 at ∼27.9 ± 1.7 ka, ∼21.8 ± 1.3 ka, and ∼15.1 ± 0.9 ka. The timing of these glacial activities is roughly in agreement with North Atlantic millennial-scale climate oscillations (Heinrich events), suggesting the potential correlations between these abrupt climate changes and glacial fluctuations in the Mount Jaggang area. The successively reduced glacial extent might have resulted from an overall decrease in Asian Summer Monsoon intensity over this timeframe.

Epidemiology of accidental radiation exposures.

PubMed Central

Cardis, E

1996-01-01

Much of the information on the health effects of radiation exposure available to date comes from long-term studies of the atomic bombings in Hiroshima and Nagasaki. Accidental exposures, such as those resulting from the Chernobyl and Kyshtym accidents, have as yet provided little information concerning health effects of ionizing radiation. This paper will present the current state of our knowledge concerning radiation effects, review major large-scale accidental radiation exposures, and discuss information that could be obtained from studies of accidental exposures and the types of studies that are needed. PMID:8781398

The Lateglacial to Holocene transition as recorded by glacier fluctuations

NASA Astrophysics Data System (ADS)

Schindelwig, I.; Akçar, N.; Kubik, P. W.; Schlüchter, C.

2009-04-01

Examination of glacier associated records may contribute to a better understanding of the ice-continent-ocean-atmosphere interactions, since glacial deposits related to short-term temperature fluctuations, driven by climate change, might be preserved. Surface exposure dating (SED) of such glacial deposits can improve the chronology of climate records. The western Swiss Alps repeatedly hosted mountain glaciers during the Pleistocene, and even during the Last Glacial-Interglacial transition, with abundant stadial and interstadial transitions during the Lateglacial (e.g. Björck et al. 1998). In this study, the adjacent valleys of Belalp and Great Aletsch (catchment area is generally south facing) in the western Swiss Alps are investigated. The slow responding Great Aletsch valley glacier shows only one confirmed moraine ridge related to the Lateglacial (Egesen stadial) (Kelly et al. 2004). However, the rather fast responding Unnerbäch cirque (recent) glacier at the Belalp (a similarly exposed - and tributary - valley to the Great Aletsch valley), features 6 individual lateral-terminal moraine ridges related to Lateglacial and early Holocene times. In the Belalp valley, 22 erratic boulders from four out of six well-preserved moraines were sampled in order to establish a detailed chronological framework. From the Great Aletsch valley four samples (boulder and ice moulded bedrock) of the lateral moraine were collected for SED. Our 10Be exposure dates suggest a stabilization of the Great Aletsch moraine related to the Egesen advance in the beginning of the Younger Dryas, assuming that the ages of the oldest erratic boulders on a single moraine ridge are representative for the time of moraine stabilization (Putkonen & Swanson, 2003). According to our investigations on the right-lateral moraine and the dataset (recalculated from Kelly et al. 2004) for the left-lateral moraine, the Egesen stadial is the first preserved re-advance after the last deglaciation. In contrast, the glacier at the Belalp shows multiple advances during the Lateglacial to early Holocene. 10Be exposure age data suggest that the outer moraine ridge can be an advance older than the Egesen stadial and younger than the LGM. This is in concert with other Younger Dryas related glacial landsystems in Switzerland (reviewing the outer moraine ages e.g. Julier Pass, Ivy-Ochs et al. 1996, 2008). A large number of Lateglacial moraines have been identified and relative correlations on the basis of elevation, equilibrium line altitude (Gross et al. 1977; Maisch, 1987) and morphological characteristics have been established. Nevertheless, it remains important to refine the absolute chronology in order to put further temporal constraints on these relative frameworks. This allows the allocation of such absolutely dated deposits to distinguished cold phases (Preboreal oscillation, Younger Dryas, Aegelsee oscillation) thus underlining their potential significance in the context of regional, as well as global Lateglacial climate conditions. The 10Be exposure ages from an inner moraine ridge are in a good agreement with the recalculated previously published 10Be exposure ages from the Egesen moraines in the Alps. This suggests a synchronicity of the Egesen stadial in the European Alps at the end of the Younger Dryas cold phase. REFERENCES Björck, S., Walker, M. J.C., Cwynar, L.C., Johnson, S., Knudsen, K-L., Lowe, J. J. & Wohlfarth, B. (1998): An event stratigraphy for the Last Termination in the North Atlantic region based on the Greenland ice-core record: a proposal by the INTIMATE group. Journal of Quarternary Science, 13, 283-292. Gross, G., Kerschner, H. & Patzelt, G. (1977): Methodische Untersuchungen über die Schneegrenze in alpinen Gletschergebieten. Zeitschrift für Gletscherkunde und Glazialgeologie, 12, 223-251. Ivy-Ochs, S., Kerschner, H., Reuther, A., Preusser, F., Heine, K., Maisch, M., Kubik, P.W. & Schlüchter, C. (2008): Chronology of the last glacial cycle in the European Alps. Journal of Quaternary Science, 23, 559-573. Ivy-Ochs, S., Schlüchter, C., Kubik, P. W., Synal, H.-A., Beer, J., Kerschner, H. (1996): The exposure age of an Egesen moraine at Julier Pass, Switzerland, measured with the cosmogenic radionuclides 10Be, 26Al and 36Cl. Eclogae geol. Helv., 89, 1049-1063. Kelly, M.A., Kubik, P.W., von Blanckenburg, F. & Schlüchter, C. (2004): Surface exposure dating of the Great Aletsch Glacier Egesen moraine system, western Swiss Alps, using the cosmogenic nuclide 10Be. Journal of Quarternary Science, 19, 431-441. Maisch, M. (1987): Zur Gletschergeschichte des alpinen Spätglazials: Analyse und Interpretation von Schneegrenzdaten. Geographica Helvetica, 42, 63-71. Putkonen, J. & Swanson, T. (2003): Accuracy of cosmogenic ages for moraines. Quarternary Research, 59, 255-261.

Modeling Population and Ecosystem Response to Sublethal Toxicant Exposure

DTIC Science & Technology

2000-09-30

Modeling Population and Ecosystem Response to Sublethal Toxicant Exposure Principal Investigator: Roger M. Nisbet Department of Ecology, Evolution...DATES COVERED 00-00-2000 to 00-00-2000 4. TITLE AND SUBTITLE Modeling Population and Ecosystem Response to Sublethal Toxicant Exposure 5a...those of real populations. We have also investigated how toxicants may affect the stability of the system. If the toxicant effect is primarily an

Insight into the expression variation of metal-responsive genes in the seedling of date palm (Phoenix dactylifera).

PubMed

Chaâbene, Zayneb; Rorat, Agnieszka; Rekik Hakim, Imen; Bernard, Fabien; Douglas, Grubb C; Elleuch, Amine; Vandenbulcke, Franck; Mejdoub, Hafedh

2018-04-01

Phytochelatin synthase and metallothionein gene expressions were monitored via qPCR in order to investigate the molecular mechanisms involved in Cd and Cr detoxification in date palm (Phoenix dactylifera). A specific reference gene validation procedure using BestKeeper, NormFinder and geNorm programs allowed selection of the three most stable reference genes in a context of Cd or Cr contamination among six reference gene candidates, namely elongation factor α1, actin, aldehyde dehydrogenase, SAND family, tubulin 6 and TaTa box binding protein. Phytochelatin synthase (pcs) and metallothionein (mt) encoding gene expression were induced from the first days of exposure. At low Cd stress (0.02 mM), genes were still up-regulated until 60th day of exposure. At the highest metal concentrations, however, pcs and mt gene expressions decreased. pcs encoding gene was significantly up-regulated under Cr exposure, and was more responsive to increasing Cr concentration than mt encoding gene. Moreover, exposure to Cd or Cr influenced clearly seed germination and hypocotyls elongation. Thus, the results have proved that both analyzed genes participate in metal detoxification and their expression is regulated at transcriptional level in date palm subjected to Cr and Cd stress. Consequently, variations of expression of mt and pcs genes may serve as early-warning biomarkers of metal stress in this species. Copyright © 2018 Elsevier Ltd. All rights reserved.

A Glacial Perspective on the Impact of Heinrich Stadials on North Atlantic Climate

NASA Astrophysics Data System (ADS)

Bromley, G. R.; Putnam, A. E.; Rademaker, K. M.; Balter, A.; Hall, B. L.

2017-12-01

The British Isles contain a rich geologic record of Late Pleistocene ice sheet behaviour in the NE North Atlantic basin. We are using cosmogenic 10Be surface-exposure dating, in conjunction with detailed glacial-geomorphic mapping, to reconstruct the timing and nature of cryospheric change - and thus climate variability - in northern Scotland since the Last Glacial Maximum. Our specific focus is Heinrich Stadial 1 (18,300-14,700 years ago), arguably the most significant abrupt climate event of the last glacial cycle and a major feature in global palaeoclimate records. Such constraint is needed because of currently conflicting models of how these events impact terrestrial environments and a recent hypothesis attributing this disparity to enhanced seasonality in the North Atlantic basin. To date, we have measured 10Be in > 30 samples from glacial erratics located on moraines deposited by the British Ice Sheet as it retreated from the continental shelf to its highland source regions. Our preliminary results indicate that the stadial was characterised by widespread deglaciation driven by atmospheric warming, a pattern that is suggestive of pronounced seasonality. Additionally, we report new exposure ages from moraines deposited during a subsequent phase of alpine glaciation (known locally as the Loch Lomond Readvance) that has long been attributed to the Younger Dryas stadial. With the growing focus on the full expression of stadials, and the inherent vulnerability of Europe to shifts in North Atlantic climate, developing the extant record of terrestrial glaciation and comparing these data to marine records is a critical step towards understanding the drivers of abrupt climate change.

Rapid thinning of the Laurentide Ice Sheet in coastal Maine, USA during late Heinrich Stadial 1

NASA Astrophysics Data System (ADS)

Koester, A. J.; Shakun, J. D.; Bierman, P. R.; Davis, P. T.; Corbett, L. B.; Zimmerman, S. R. H.

2016-12-01

Direct measurements of Laurentide Ice Sheet (LIS) thickness during the last deglaciation are limited, especially in coastal Maine where the LIS had a marine-terminating margin that was susceptible to abrupt climate shifts in the North Atlantic. We measured 31 10Be exposure ages down coastal mountainsides in Acadia National Park and from the slightly inland Pineo Ridge Moraine Complex, a 100 km long glaciomarine delta, to date the timing and rate of LIS thinning and subsequent retreat in coastal Maine. The vertical transects in Acadia have indistinguishable exposure ages over a 300 m range of elevation, suggesting rapid, century-scale thinning centered at 15 ka, similar to abrupt thinning inferred from cosmogenic nuclide ages at Mt. Katahdin in central Maine (Davis et al., 2015). This rapid ice sheet surface lowering during the latter part of the cold Heinrich Stadial 1 event may have been due to rapid calving in the Gulf of Maine, perhaps related to regional oceanic warming associated with weakened Atlantic Meridional Overturning Circulation (AMOC) at this time. Our 10Be ages are substantially younger than radiocarbon constraints on LIS retreat in the coastal lowlands, suggesting that the deglacial marine reservoir effect in this area was greater than the 450 - 600 year correction previously used, perhaps also related to the sluggish AMOC. In addition, the Pineo Ridge Moraine Complex dates to 14.4 ± 0.4 ka, indicating that the LIS margin began retreating from coastal Maine near the onset of the Bølling Interstadial warming.

Regional mid-Pleistocene glaciation in central Patagonia

NASA Astrophysics Data System (ADS)

Hein, Andrew S.; Cogez, Antoine; Darvill, Christopher M.; Mendelova, Monika; Kaplan, Michael R.; Herman, Frédéric; Dunai, Tibor J.; Norton, Kevin; Xu, Sheng; Christl, Marcus; Rodés, Ángel

2017-05-01

Southern South America contains a glacial geomorphological record that spans the past million years and has the potential to provide palaeoclimate information for several glacial periods in Earth's history. In central Patagonia, two major outlet glaciers of the former Patagonian Ice Sheet carved deep basins ∼50 km wide and extending over 100 km into the Andean plain east of the mountain front. A succession of nested glacial moraines offers the possibility of determining when the ice lobes advanced and whether such advances occurred synchronously. The existing chronology, which was obtained using different methods in each valley, indicates the penultimate moraines differ in age by a full glacial cycle. Here, we test this hypothesis further using a uniform methodology that combines cosmogenic nuclide ages from moraine boulders, moraine cobbles and outwash cobbles. 10Be concentrations in eighteen outwash cobbles from the Moreno outwash terrace in the Lago Buenos Aires valley yield surface exposure ages of 169-269 ka. We find 10Be inheritance is low and therefore use the oldest surface cobbles to date the deposit at 260-270 ka, which is indistinguishable from the age obtained in the neighbouring Lago Pueyrredón valley. This suggests a regionally significant glaciation during Marine Isotope Stage 8, and broad interhemispheric synchrony of glacial maxima during the mid to late Pleistocene. Finally, we find the dated outwash terrace is 70-100 ka older than the associated moraines. On the basis of geomorphological observations, we suggest this difference can be explained by exhumation of moraine boulders.

INHALATION EXPOSURE TO CARBON NANOTUBES (CNT) AND CARBON NANOFIBERS (CNF): METHODOLOGY AND DOSIMETRY

PubMed Central

Oberdörster, Günter; Castranova, Vincent; Asgharian, Bahman; Sayre, Phil

2015-01-01

Carbon nanotubes (CNT) and nanofibers (CNF) are used increasingly in a broad array of commercial products. Given current understandings, the most significant life-cycle exposures to CNT/CNF occur from inhalation when they become airborne at different stages of their life cycle, including workplace, use, and disposal. Increasing awareness of the importance of physicochemical properties as determinants of toxicity of CNT/CNF and existing difficulties in interpreting results of mostly acute rodent inhalation studies to date necessitate a reexamination of standardized inhalation testing guidelines. The current literature on pulmonary exposure to CNT/CNF and associated effects is summarized; recommendations and conclusions are provided that address test guideline modifications for rodent inhalation studies that will improve dosimetric extrapolation modeling for hazard and risk characterization based on the analysis of exposure-dose-response relationships. Several physicochemical parameters for CNT/CNF, including shape, state of agglomeration/aggregation, surface properties, impurities, and density, influence toxicity. This requires an evaluation of the correlation between structure and pulmonary responses. Inhalation, using whole-body exposures of rodents, is recommended for acute to chronic pulmonary exposure studies. Dry powder generator methods for producing CNT/CNF aerosols are preferred, and specific instrumentation to measure mass, particle size and number distribution, and morphology in the exposure chambers are identified. Methods are discussed for establishing experimental exposure concentrations that correlate with realistic human exposures, such that unrealistically high experimental concentrations need to be identified that induce effects under mechanisms that are not relevant for workplace exposures. Recommendations for anchoring data to results seen for positive and negative benchmark materials are included, as well as periods for postexposure observation. A minimum data set of specific bronchoalveolar lavage parameters is recommended. Retained lung burden data need to be gathered such that exposure-dose-response correlations may be analyzed and potency comparisons between materials and mammalian species are obtained considering dose metric parameters for interpretation of results. Finally, a list of research needs is presented to fill data gaps for further improving design, analysis, and interpretation and extrapolation of results of rodent inhalation studies to refine meaningful risk assessments for humans. PMID:26361791

A pilot study to rate determinants of exposure from videotaped work activities of farmers' use of pesticides.

PubMed

Prince, J R; Stewart, P A; Nam, J M; Blair, A

2001-10-01

Industrial hygienists often observe workers to determine who should be measured based on a predicted exposure level. Such evaluations are usually based on real-time observation, yet surprisingly little research has been conducted on what determinants of exposure industrial hygienists use to rank workers and whether the ranking is accurate. Accuracy of the ranking may also be affected by the observation process, which is limited when conditions in the workers' immediate environment are rapidly changing. An alternative to real-time observation is videotaping workers and evaluating the tapes at a later date. A pilot study was conducted using previously collected data to determine if workers could be ranked by exposure level utilizing a scoring system to rate videotaped work practices. Six farmers had been videotaped and their dermal exposures measured as they applied insecticide to hogs. In this study, scores were developed to rate the farmers' working conditions by exposure level. Two types of determinants were used to describe exposure: touching and work practices. Touching included the number of times parts of the body had contact with surfaces possibly contaminated with insecticide. Work practices included the types of clothing and protective equipment worn as well as specific practices used by the farmer (e.g., application method). Two raters conducted independent assessments of the videotape using the same criteria. One rater reviewed the tape twice. Agreement between the raters for the "touching" score was weak (intra-class coefficient (ICC) = 0.28), but there was excellent agreement between the two raters (ICC = 0.92) for overall quality of work practices. As expected, a greater number of touches was moderately correlated with an increase in total exposure (rs = 0.60) and there was a weak inverse relationship between protective work practices and the exposure under the clothing (rs = -0.26). All other relationships with exposure level were contrary to what was expected. Since videotapes provide the industrial hygienist with a record of work events and can capture details that might otherwise be missed or not considered they may play a useful role in exposure assessment, especially if carefully developed procedures are followed to overcome the limitations found by this pilot study.

Evidence of Multiple Ground-rupturing Earthquakes in the Past 4000 Years along the Pasuruan Fault, East Java, Indonesia

NASA Astrophysics Data System (ADS)

Marliyani, G. I.; Arrowsmith, R.; Helmi, H.

2015-12-01

Instrumental and historical records of earthquakes, supplemented by paleoeseismic constraints can help reveal the earthquake potential of an area. The Pasuruan fault is a high angle normal fault with prominent youthful scarps cutting young deltaic sediments in the north coast of East Java, Indonesia and may pose significant hazard to the densely populated region. This fault has not been considered a significant structure, and mapped as a lineament with no sense of motion. Information regarding past earthquakes along this fault is not available. The fault is well defined both in the imagery and in the field as a ~13km long, 2-50m-high scarp. Open and filled fractures and natural exposures of the south-dipping fault plane indicate normal sense of motion. We excavated two fault-perpendicular trenches across a relay ramp identified during our surface mapping. Evidence for past earthquakes (documented in both trenches) includes upward fault termination with associated fissure fills, colluvial wedges and scarp-derived debris, folding, and angular unconformities. The ages of the events are constrained by 23 radiocarbon dates on detrital charcoal. We calibrated the dates using IntCal13 and used Oxcal to build the age model of the events. Our preliminary age model indicates that since 2006±134 B.C., there has been at least five ground rupturing earthquakes along the fault. The oldest event identified in the trench however, is not well-dated. Our modeled 95th percentile ranges of the next four earlier earthquakes (and their mean) are A.D. 1762-1850 (1806), A.D. 1646-1770 (1708), A.D. 1078-1648 (1363), and A.D. 726-1092 (909), yielding a rough recurrence rate of 302±63 yrs. These new data imply that Pasuruan fault is more active than previously thought. Additional well-dated earthquakes are necessary to build a solid earthquake recurrence model. Rupture along the whole section implies a minimum earthquake magnitude of 6.3, considering 13km as the minimum surface rupture length.

Physical State of Ices in the Outer Solar System. Revised

NASA Technical Reports Server (NTRS)

Roush, Ted L.; DeVincenzi, Donald (Technical Monitor)

2001-01-01

Comparison of the identity and abundances of ices observed around protostars and those associated with comets clearly suggests that comets preserve the heritage of the interstellar materials that aggregated to form them. However, the ability to identify these same species on icy satellites in the outer solar system is a complex function of the composition of the original ices, their subsequent thermal histories, and their exposure to various radiation environments. Our ability to identify the ices currently present on objects in the outer solar system relies upon observational and laboratory, and theoretical efforts. To date there is ample observational evidence for crystalline water ice throughout the outer solar system. In addition, there is growing evidence that amorphous ice may be present on some bodies. More volatile ices, e.g. N2, CH4. CO, and other species, e.g. ammonia hydrate, are identified on objects lying at and beyond Uranus. Both photolysis and radiolysis play important roles in altering the original surfaces due to chemical reactions and erosion of the surface. Ultraviolet photolysis appears to dominate alteration of the upper few hundred Angstroms, although sputtering the surface can sometimes be a significantly competitative process; dominating on icy surfaces embedded in a strong planetary magnetospheric field. There is growing observational evidence that the by-products of photolysis and radiolysis, suggested on a theoretical basis, are present on icy surfaces.

75 FR 27188 - Revising the Notification Requirements in the Exposure Determination Provisions of the Hexavalent...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-14

... Health Administration (OSHA); Department of Labor. ACTION: Final rule; confirmation of effective date. SUMMARY: OSHA is confirming the effective date of its direct final rule (DFR) revising the employee...(VI)). In the March 17, 2010, DFR document, OSHA stated that the DFR would become effective on June 15...

Public Health Impact of Wildfire Emissions: Up-date on the Wildfire Smoke Guide, Public Health Information and Communications Research

EPA Science Inventory

EPA Tools and Resources Webinar: Public Health Impact of Wildfire Smoke Emissions Specific strategies to reduce smoke exposure and the Smoke Sense App As the start of the summer wildfire season approaches, public officials, communities and individuals need up-to-date wildfire smo...

Fumigation characteristics of ozone in postharvest treatment of Kabkab dates (Phoenix dactylifera L.) against selected insect infestation.

PubMed

Niakousari, Mehrdad; Erjaee, Zahra; Javadian, Shahram

2010-04-01

Methyl bromide fumigation, the most accepted quarantine treatment for dates and many other dried commodities, will be phased out by 2015 worldwide. As a result, there is a critical need to develop durable alternatives for methyl bromide as postharvest treatments of agricultural commodities. This article presents a new method for postharvest treatment of Kabkab dates (Phoenix dactylifera L.) by application of gaseous ozone to reduce or eliminate all life stages (adults, larvae, and eggs) of Indian meal moth (Plodia interpunctella) and sawtooth grain beetle (Oryzaephilus surinamensis). The effect of the ozonation process on the sugar content of dates was also evaluated. Infested dates were exposed to ozone concentrations of 600, 1,200, 2,000, and 4,000 ppm for 1 and 2 h. As insect eggs are known to be most tolerant to many chemical or physical treatments, they were additionally exposed to an atmosphere of pure carbon dioxide prior to ozonation. Exposing samples to ozone concentrations of >2,000 ppm for 2 h resulted in complete mortality of larvae and adults. Exposure to 4,000 ppm of ozone for 2 h resulted in 80% mortality of eggs, and exposure to CO(2) prior to ozonation did not improve the effect of ozonation on eggs. Ozone did not have any influence on the sugar content of Kabkab dates.

Exploring the Gingival Recession Surgical Treatment Modalities: A Literature Review

PubMed Central

Shkreta, Mirsad; Atanasovska-Stojanovska, Aneta; Dollaku, Blerta; Belazelkoska, Zlatanka

2018-01-01

Gingival recessions present complex soft tissue pathology, with a multiple aetiology and a high prevalence which increases with age. They are defined as an exposure of the root surface of the teeth as a result of the apical migration of the gingival margin beyond the cementum-enamel junction, causing functional and aesthetic disturbances to the affected individuals. Aiming to ensure complete root coverage and satisfying aesthetic outcomes, a wide range of surgical techniques have been proposed through the decades for the treatment of the gingival recessions. The following literature review attempts to provide a comprehensive, structured and up-to-date summary of the relevant literature regarding these surgical techniques, aiming to emphasise for each technique its indications, its long-term success and predictability, its advantages and disadvantages about each other. PMID:29731944

49 CFR 1150.13 - Relevant dates.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 8 2011-10-01 2011-10-01 false Relevant dates. 1150.13 Section 1150.13 Transportation Other Regulations Relating to Transportation (Continued) SURFACE TRANSPORTATION BOARD, DEPARTMENT... Designated Operators § 1150.13 Relevant dates. The exact dates of the period of operation which have been...

Cutaneous exposure scenarios for engineered nanoparticles used in semiconductor fabrication: a preliminary investigation of workplace surface contamination.

PubMed

Shepard, Michele; Brenner, Sara

2014-01-01

Numerous studies are ongoing in the fields of nanotoxicology and exposure science; however, gaps remain in identifying and evaluating potential exposures from skin contact with engineered nanoparticles in occupational settings. The aim of this study was to identify potential cutaneous exposure scenarios at a workplace using engineered nanoparticles (alumina, ceria, amorphous silica) and evaluate the presence of these materials on workplace surfaces. Process review, workplace observations, and preliminary surface sampling were conducted using microvacuum and wipe sample collection methods and transmission electron microscopy with elemental analysis. Exposure scenarios were identified with potential for incidental contact. Nanoparticles of silica or silica and/or alumina agglomerates (or aggregates) were identified in surface samples from work areas where engineered nanoparticles were used or handled. Additional data are needed to evaluate occupational exposures from skin contact with engineered nanoparticles; precautionary measures should be used to minimize potential cutaneous exposures in the workplace.

76 FR 68183 - Highlights of the Exposure Factors Handbook: 2011 Update Release of Final Report

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-03

... Update Release of Final Report AGENCY: Environmental Protection Agency (EPA). ACTION: Notice of availability. SUMMARY: EPA is announcing the release of the report Highlights of the Exposure Factors Handbook... environmental agents. Dated: October 27, 2011. Darrell A. Winner, Acting Director, National Center for...

76 FR 22620 - Triflusulfuron-Methyl; Pesticide Tolerances

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-22

... under the Federal Food, Drug, and Cosmetic Act (FFDCA). DATES: This regulation is effective April 22... Determination of Safety Section 408(b)(2)(A)(i) of FFDCA allows EPA to establish a tolerance (the legal limit... determination on aggregate exposure for triflusulfuron-methyl, including exposure resulting from the tolerances...

The Effects of Sleep on the Performance of Marines Following Exposure to Waterborne Motion

DTIC Science & Technology

2013-03-01

based on each participants’ grouping or cluster. As participants obtain less sleep, their marksmanship scores are expected to decrease. Obstacle... ON THE PERFORMANCE OF MARINES FOLLOWING EXPOSURE TO WATERBORNE MOTION by Cynthia Gelpi March 2013 Thesis Advisor: Nita Lewis...3. REPORT TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE The Effects of Sleep on the Performance of Marines Following Exposure to

10Be exposure dating of the timing of Neoglacial glacier advances in the Ecrins-Pelvoux massif, southern French Alps

NASA Astrophysics Data System (ADS)

Le Roy, Melaine; Deline, Philip; Carcaillet, Julien; Schimmelpfennig, Irene; Ermini, Magali; Aster Team

2017-12-01

Alpine glacier variations are known to be reliable proxies of Holocene climate. Here, we present a terrestrial cosmogenic nuclide (TCN)-based glacier chronology relying on 24 new 10Be exposure ages, which constrain maximum Neoglacial positions of four small to mid-sized glaciers (Rateau, Lautaret, Bonnepierre and Etages) in the Ecrins-Pelvoux massif, southern French Alps. Glacier advances, marked by (mainly lateral) moraine ridges that are located slightly outboard of the Little Ice Age (LIA, c. 1250-1860 AD) maximum positions, were dated to 4.25 ± 0.44 ka, 3.66 ± 0.09 ka, 2.09 ± 0.10 ka, c. 1.31 ± 0.17 ka and to 0.92 ± 0.02 ka. The '4.2 ka advance', albeit constrained by rather scattered dates, is to our knowledge exposure-dated here for the first time in the Alps. It is considered as one of the first major Neoglacial advance in the western Alps, in agreement with other regional paleoclimatological proxies. We further review Alpine and Northern Hemisphere mid-to-high latitude evidence for climate change and glacier activity concomitant with the '4.2 ka event'. The '2.1 ka advance' was not extensively dated in the Alps and is thought to represent a prominent advance in early Roman times. Other Neoglacial advances dated here match the timing of previously described Alpine Neoglacial events. Our results also suggest that a Neoglacial maximum occurred at Etages Glacier 0.9 ka ago, i.e. during the Medieval Climate Anomaly (MCA, c. 850-1250 AD). At Rateau Glacier, discordant results are thought to reflect exhumation and snow cover of the shortest moraine boulders. Overall, this study highlights the need to combine several sites to develop robust Neoglacial glacier chronologies in order to take into account the variability in moraine deposition pattern and landform obliteration and conservation.

Determination of heavy metals in the fruit of date palm growing at different locations of Riyadh.

PubMed

Aldjain, Ibrahim M; Al-Whaibi, Mohamed H; Al-Showiman, Salim S; Siddiqui, Manzer H

2011-04-01

Exposure of heavy metals to human beings has risen dramatically in the last 50 years. In today's urban and industrial society, there is no escaping from exposure to toxic chemicals and heavy metals. Humans are more likely to be exposed to heavy metal contamination from the dust that adheres to edible plants than from bioaccumulation. This is because it is very difficult to wash off all the dust particles from the plant material before ingesting them. The objectives of this experiment were to determine the concentrations of lead (Pb) and cadmium (Cd) in washing residues and in the tissues of fruits of date palm growing in 14 sites of Riyadh and also to assess whether the fruits were safe for human consumption. The washing residues and tissue of date palm fruits collected from different sites showed the presence of significant amounts of the Pb and Cd. The concentration of Pb in the dust and fruit tissue increased with increasing anthropogenic sources. Therefore, fruits of date palm might be used as a pollution indicator; it might be recommend that fruits of date palm could be safe for human consumption after washing. The mean concentration of Pb and Cd in all the samples collected from different sites is within the safe limits recommended by FAO/WHO.

Occupational exposure to extremely low frequency magnetic fields and brain tumour risks in the INTEROCC study

PubMed Central

Turner, Michelle C; Benke, Geza; Bowman, Joseph D; Figuerola, Jordi; Fleming, Sarah; Hours, Martine; Kincl, Laurel; Krewski, Daniel; McLean, Dave; Parent, Marie-Elise; Richardson, Lesley; Sadetzki, Siegal; Schlaefer, Klaus; Schlehofer, Brigitte; Schüz, Joachim; Siemiatycki, Jack; van Tongeren, Martie; Cardis, Elisabeth

2014-01-01

Background Occupational exposure to extremely low frequency magnetic fields (ELF) is a suspected risk factor for brain tumours, however the literature is inconsistent. Few studies have assessed whether ELF in different time windows of exposure may be associated with specific histologic types of brain tumours. This study examines the association between ELF and brain tumours in the large-scale INTEROCC study. Methods Cases of adult primary glioma and meningioma were recruited in seven countries (Australia, Canada, France, Germany, Israel, New Zealand, United Kingdom) between 2000 and 2004. Estimates of mean workday ELF exposure based on a job exposure matrix assigned. Estimates of cumulative exposure, average exposure, maximum exposure, and exposure duration were calculated for the lifetime, and 1–4, 5–9, and 10+ years prior to the diagnosis/reference date. Results There were 3,761 included brain tumour cases (1,939 glioma, 1,822 meningioma) and 5,404 population controls. There was no association between lifetime cumulative ELF exposure and glioma or meningioma risk. However, there were positive associations between cumulative ELF 1–4 years prior to the diagnosis/reference date and glioma (odds ratio (OR) ≥ 90th percentile vs < 25th percentile = 1.67, 95% confidence interval (CI) 1.36–2.07, p < 0.0001 linear trend), and, somewhat weaker associations with meningioma (OR ≥ 90th percentile vs < 25th percentile = 1.23, 95% CI 0.97–1.57, p = 0.02 linear trend). Conclusions Results showed positive associations between ELF in the recent past and glioma. Impact Occupational ELF exposure may play a role in the later stages (promotion and progression) of brain tumourigenesis. PMID:24935666

Informing aetiologic research priorities for squamous cell oesophageal cancer in Africa: A review of setting-specific exposures to known and putative risk factors

PubMed Central

McCormack, V; Menya, D; Munishi, MO; Dzamalala, C; Gasmelseed, N; Roux, M Leon; Assefa, M; Odipo, O; Watts, M; Mwasamwaja, AO; Mmbaga, BT; Murphy, G; Abnet, CC; Dawsey, SM; Schüz, J

2018-01-01

Oesophageal squamous cell carcinoma (ESCC) is one of the most common cancers in most Eastern and Southern African countries, but its aetiology has been understudied to date. To inform its research agenda, we undertook a review to identify, of the ESCC risk factors that have been established or strongly suggested worldwide, those with a high prevalence or high exposure levels in any ESCC-affected African setting and the sources thereof. We found that for almost all ESCC risk factors known to date, including tobacco, alcohol, hot beverage consumption, nitrosamines and both inhaled and ingested PAHs, there is evidence of population groups with raised exposures, the sources of which vary greatly between cultures across the ESCC corridor. Research encompassing these risk factors is warranted and is likely to identify primary prevention strategies. PMID:27466161

The drainage of the Baltic Ice Lake and a new Scandinavian reference 10Be production rate

NASA Astrophysics Data System (ADS)

Stroeven, Arjen P.; Heyman, Jakob; Fabel, Derek; Björck, Svante; Caffee, Marc W.; Fredin, Ola; Harbor, Jonathan M.

2015-04-01

An important constraint on the reliability of cosmogenic nuclide exposure dating is the derivation of tightly controlled production rates. We present a new dataset for 10Be production rate calibration from Mount Billingen, southern Sweden, the site of the final drainage of the Baltic Ice Lake, an event dated to 11,620 ± 100 cal yr BP. Nine samples of flood-scoured bedrock surfaces and depositional boulders and cobbles unambiguously connected to the drainage event yield a reference 10Be production rate of 4.09 ± 0.22 atoms g-1 yr-1 for the CRONUS Lm scaling and 3.93 ± 0.21 atoms g-1 yr-1 for the LSD general spallation scaling. We also recalibrate the reference 10Be production rates for four sites in Norway and combine these with the Billingen results to derive a tightly clustered Scandinavian reference 10Be production rate of 4.12 ± 0.10 (4.12 ± 0.25 for altitude scaling) atoms g-1 yr-1 for the Lm scaling scheme and 3.96 ± 0.10 (3.96 ± 0.24 for altitude scaling) atoms g-1 yr-1 for the LSD scaling scheme.

Occupational exposure to beryllium in French enterprises: a survey of airborne exposure and surface levels.

PubMed

Vincent, Raymond; Catani, Jacques; Créau, Yvon; Frocaut, Anne-Marie; Good, Andrée; Goutet, Pierre; Hou, Alain; Leray, Fabrice; André-Lesage, Marie-Ange; Soyez, Alain

2009-06-01

An assessment survey of occupational exposure to beryllium (Be) was conducted in France between late 2004 and the end of 2006. Exposure estimates were based on the analytical results of samples collected from workplace air and from work surfaces in 95 facilities belonging to 37 sectors of activity. The results of this study indicated airborne Be concentrations in excess of the occupational exposure limit value of 2 microg m(-3) recommended in France. Metallurgy and electronic component manufacturing represented the activities and occupations where workers had the highest arithmetic mean exposures to Be. Surface contamination levels were also high and frequently exceeded thresholds recommended by different bodies. These results should prompt the development of prevention programmes that include Be substitution, process control and surface decontamination, in conjunction with suitable medical surveillance.

40 CFR 63.784 - Compliance dates.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 10 2011-07-01 2011-07-01 false Compliance dates. 63.784 Section 63... Emission Standards for Shipbuilding and Ship Repair (Surface Coating) § 63.784 Compliance dates. (a) Each owner or operator of an existing affected source shall comply within two years after the effective date...

Quantification of Acute Vocal Fold Epithelial Surface Damage with Increasing Time and Magnitude Doses of Vibration Exposure

PubMed Central

Kojima, Tsuyoshi; Van Deusen, Mark; Jerome, W. Gray; Garrett, C. Gaelyn; Sivasankar, M. Preeti; Novaleski, Carolyn K.; Rousseau, Bernard

2014-01-01

Because the vocal folds undergo repeated trauma during continuous cycles of vibration, the epithelium is routinely susceptible to damage during phonation. Excessive and prolonged vibration exposure is considered a significant predisposing factor in the development of vocal fold pathology. The purpose of the present study was to quantify the extent of epithelial surface damage following increased time and magnitude doses of vibration exposure using an in vivo rabbit phonation model. Forty-five New Zealand white breeder rabbits were randomized to nine groups and received varying phonation time-doses (30, 60, or 120 minutes) and magnitude-doses (control, modal intensity phonation, or raised intensity phonation) of vibration exposure. Scanning electron microscopy and transmission electron microscopy was used to quantify the degree of epithelial surface damage. Results revealed a significant reduction in microprojection density, microprojection height, and depth of the epithelial surface with increasing time and phonation magnitudes doses, signifying increased epithelial surface damage risk with excessive and prolonged vibration exposure. Destruction to the epithelial cell surface may provide significant insight into the disruption of cell function following prolonged vibration exposure. One important goal achieved in the present study was the quantification of epithelial surface damage using objective imaging criteria. These data provide an important foundation for future studies of long-term tissue recovery from excessive and prolonged vibration exposure. PMID:24626217

The Impact of Intimate Partner Violence on Decisions to Leave Dating Relationships: A Test of the Investment Model

ERIC Educational Resources Information Center

Rhatigan, Deborah L.; Street, Amy E.

2005-01-01

This study explored the impact of violence exposure on investment-model constructs within a sample of college women involved in heterosexual dating relationships. Results generally supported the "common sense" hypothesis, suggesting that violence negatively impacts satisfaction for and commitment to one's relationship and is positively associated…

Laurentide ice sheet meltwater routing along the Iro-Mohawk River, eastern New York, USA

NASA Astrophysics Data System (ADS)

Porreca, Charles; Briner, Jason P.; Kozlowski, Andrew

2018-02-01

The rerouting of meltwater as the configuration of ice sheets evolved during the last deglaciation is thought to have led to some of the most significant perturbations to the climate system in the late Quaternary. However, the complex pattern of ice sheet meltwater drainage off the continents, and the timing of rerouting events, remains to be fully resolved. As the Laurentide Ice Sheet (LIS) retreated north of the Adirondack Uplands of northeastern New York State during the last deglaciation, a large proglacial lake, Lake Iroquois, found a lower outlet that resulted in a significant flood event. This meltwater rerouting event, from outflow via the Iro-Mohawk River valley (southern Adirondack Mountains) to the spillway at Covey Hill (northeastern Adirondack Mountains), is hypothesized to have taken place 13.2 ka and disturbed meridional circulation in the North Atlantic Ocean. However, the timing of the rerouting event is not certain because the event has not been directly dated. With improving the history of Lake Iroquois drainage in mind, we obtained cosmogenic 10Be exposure ages on a strath terrace on Moss Island, along the Iro-Mohawk River spillway. We hypothesize that Moss Island's strath terrace became abandoned during the rerouting event. Six 10Be ages from the strath surface average 14.8 ± 1.3 ka, which predates the previously published bracketing radiocarbon ages of 13.2 ka. Several possibilities for the discrepancy exist: (1) the 10Be age accurately represents the timing of a decrease in discharge through the Iro-Mohawk River spillway; (2) the age is influenced by inheritance. The 10Be ages from glacially sculpted surfaces on Moss Island above the strath terrace predate the deglaciation of the site by 5 to 35 ky; and (3) the abandonment of the Moss Island strath terrace relates to knickpoint migration and not the final abandonment of the Iro-Mohawk River as the Lake Iroquois spillway. Further study and application of cosmogenic 10Be exposure dating in the region may lead to tighter chronologic constraints of meltwater history of the LIS.

Indirect Dietary Residential Exposure Assessment Model (IDREAM) Implementation

EPA Pesticide Factsheets

The Indirect Dietary Residential Exposure Assessment Model (IDREAM) estimates indirect ingestion exposure to disinfectants used in residential settings on hard surfaces where there may be inadvertent transfer to edible items prepared on those surfaces.

Risk of severe acute liver injury among patients with brain cancer treated with temozolomide: a nested case-control study using the healthcore integrated research database.

PubMed

Desai, Vibha C A; Quinlan, Scott C; Deitz, Anne C; He, Jinghua; Holick, Crystal N; Lanes, Stephan

2017-08-01

Temozolomide (TMZ) is used to treat adult patients with glioblastoma multiforme (GBM). Cases of hepatotoxicity have been reported among patients using TMZ. The objective of the study was to assess the relation, if any, between exposure to TMZ and serious acute liver injury (SALI). We used the HealthCore Integrated Research Database to perform a case-control study nested within a retrospective cohort of adult patients aged 18-100 years with at least two diagnoses of brain cancer anytime between 2006 and 2014. Patients without continuous eligibility or with a SALI diagnosis within 6 months prior to the date of incident brain cancer diagnosis were excluded. Medical records were sought for potential SALI cases and reviewed by two hepatologists. Five controls were selected for each case using incidence density sampling, matched on age and calendar year of index date. The analysis included 61 confirmed SALI cases and 305 selected controls. Exposure to TMZ was classified according to dispensing date and days supply of medication dispensed. We estimated odds ratios using conditional logistic regression models. The odds ratio for any exposure to TMZ was 0.91 (95% CI 0.44-1.91), for recent exposure to TMZ was 0.62 (95% CI 0.21-1.85). There was no increased risk of SALI with increasing duration of exposure to TMZ. When patients with unconfirmed SALI were included in the analysis, results were similar (OR 1.04; 95% CI 0.70-1.54). In conclusion, this study did not find an association between TMZ and SALI risk among patients with brain cancer.

Microflora distributions in paleosols: a method for calculating the validity of radiocarbon-dated surfaces

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

Mahaney, W.C.; Boyer, M.G.

1986-08-01

Microflora (bacteria and fungi) distributions in several paleosols from Mount Kenya, East Africa, provide important information about contamination of buried soil horizons dated by radiocarbon. High counts of bacteria and fungi in buried soils provide evidence for contamination by plant root effects or ground water movement. Profiles with decreasing counts versus depth appear to produce internally consistent and accurate radiocarbon dates. Profiles with disjunct or bimodal distributions of microflora at various depths produce internally inconsistent chronological sequences of radiocarbon-dated buried surfaces. Preliminary results suggest that numbers up to 5 x 10/sup 2/ g/sup -1/ for bacteria in buried A horizonsmore » do not appear to affect the validity of /sup 14/C dates. Beyond this threshold value, contamination appears to produce younger dates, the difference between true age and /sup 14/C age increasing with the amount of microflora contamination.« less

75 FR 17164 - Asbestos in General Industry; Extension of the Office of Management and Budget's (OMB) Approval...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-05

...] Asbestos in General Industry; Extension of the Office of Management and Budget's (OMB) Approval of... Asbestos in General Industry (29 CFR 1910.1001). DATES: Comments must be submitted (postmarked, sent, or... protection from hazardous asbestos exposure. Asbestos exposure results in asbestosis, an emphysema-like...

78 FR 34406 - Asbestos in General Industry; Extension of the Office of Management and Budget's (OMB) Approval...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-07

...] Asbestos in General Industry; Extension of the Office of Management and Budget's (OMB) Approval of... requirements specified in the Standard on Asbestos in General Industry (29 CFR 1910.1001). DATES: Comments must... protection from exposure to hazardous asbestos. Asbestos exposure results in asbestosis, an emphysema-like...

SELECTIVE VULNERABILITY OF EMBRYONIC CELL POPULATIONS TO ETHANOL-INDUCED APOPTOSIS: IMPLICATIONS FOR ALCOHOL RELATED BIRTH DEFECTS AND NEURODEVELOPMENTAL DISORDER

EPA Science Inventory

The locations of cell death and resulting malformations in embryos following teratogen exposure vary depending on the teratogen used, the genotype of the conceptus, and the developmental stage of the embryo at time of exposure. To date, ethanol-induced cell death has been charac...

78 FR 17219 - National Institute of Environmental Health Sciences; Notice of Closed Meeting Pursuant to section...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-20

... Health Sciences Special Emphasis Panel, Assessment of Adverse Genetic Effects From Exposure to Compounds... Program Nos. 93.115, Biometry and Risk Estimation--Health Risks from Environmental Exposures; 93.142... Research and Testing, National Institutes of Health, HHS) Dated: March 14, 2013. Carolyn Baum, Program...

Racial and Ethnic Inequality in Childhood Exposure to Neighborhood Poverty and Affluence.

ERIC Educational Resources Information Center

Timberlake, Jeffrey, M.

Despite recent scholarly concern with "neighborhood effects" on children, no study to date has measured the cumulative exposure of children to poor and affluent neighborhoods. This study constructed multi-state life tables to estimate racial and ethnic differences in "childhood expectancy" in five neighborhood types, ranging from affluent to…

DEVELOPMENT AND VALIDATION OF THE CUMULATIVE ENVIRONMENTAL EXPOSURE INDEX FOR ARSENIC: A NOVEL ENVIRONMENTAL PUBLIC HEALTH INDICATOR

EPA Science Inventory

Arsenic (As) is a ubiquitous environmental toxin that causes a wide range of diseases. To date, however, there is no methodology for calculating the impact of cumulative As exposure on health outcomes in the US. The current project will develop and validate the Cumulative Envi...

Importance of Gender and Attitudes about Violence in the Relationship between Exposure to Interparental Violence and the Perpetration of Teen Dating Violence

PubMed Central

Shorey, Ryan C.; Tortolero, Susan R.; Wolfe, David A.; Stuart, Gregory L.

2013-01-01

Objective Mounting evidence has demonstrated a link between exposure to family of origin violence and the perpetration of teen dating violence (TDV). However, only recently have mechanisms underlying this relationship been investigated and very few studies have differentiated between exposure to father-to-mother and mother-to-father violence. Methods The current study used structural equation modeling on a large ethnically diverse school-based sample of male and female adolescents (n = 917) to address these gaps in the literature. Results For adolescent girls, there was an association between exposure to interparental violence (father-to-mother and mother-to-father) and TDV perpetration (physical violence and psychological abuse). For adolescent boys, only an association between mother-to-father violence was related to their TDV perpetration. Further, for both girls and boys, the relationship between mother-to-father violence and perpetration of TDV was fully mediated by attitudes accepting of violence. Conclusion These results suggest that attending to gender and targeting adolescents’ attitudes about violence may be viable approaches to preventing TDV. PMID:23490056

Effects of long-term exposure on LDEF fastener assemblies

NASA Astrophysics Data System (ADS)

Spear, Steve; Dursch, Harry

1992-09-01

This presentation summarizes the Systems Special Investigations Group (SIG) findings from testing and analysis of fastener assemblies used on the Long Duration Exposure Facility (LDEF) structure, the tray mounting clamps, and by the various experimenters. The LDEF deintegration team and several experimenters noted severe fastener damage and hardware removal difficulties during post-flight activities. The System SIG has investigated all reported instances, and in all cases examined to date, the difficulties were attributed to galling during installation or post-flight removal. To date, no evidence of coldwelding was found. Correct selection of materials and lubricants as well as proper mechanical procedures is essential to ensure successful on-orbit or post-flight installation and removal of hardware.

Effects of long-term exposure on LDEF fastener assemblies

NASA Technical Reports Server (NTRS)

Spear, Steve; Dursch, Harry

1992-01-01

This presentation summarizes the Systems Special Investigations Group (SIG) findings from testing and analysis of fastener assemblies used on the Long Duration Exposure Facility (LDEF) structure, the tray mounting clamps, and by the various experimenters. The LDEF deintegration team and several experimenters noted severe fastener damage and hardware removal difficulties during post-flight activities. The System SIG has investigated all reported instances, and in all cases examined to date, the difficulties were attributed to galling during installation or post-flight removal. To date, no evidence of coldwelding was found. Correct selection of materials and lubricants as well as proper mechanical procedures is essential to ensure successful on-orbit or post-flight installation and removal of hardware.

Using exterior building surface films to assess human exposure and health risks from PCDD/Fs in New York City, USA, after the World Trade Center attacks.

PubMed

Rayne, Sierra

2005-12-09

Concentrations of tetra- through octa-chlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were determined in exterior window films from Manhattan and Brooklyn in New York City (NYC), USA, 6 weeks after the World Trade Center (WTC) attacks of 11 September 2001. High concentrations of the 2,3,7,8-substituted congeners (P(2378)CDD/Fs) were observed, at levels up to 6600 pg-TEQ g(-1) nearest the WTC site. An equilibrium partitioning model was developed to reconstruct total gas + particle-phase atmospheric concentrations of P(2378)CDD/Fs at each site. The reconstructed atmospheric and window film concentrations were subsequently used in a preliminary human health risk assessment to estimate the potential cancer and non-cancer risks posed to residents of lower Manhattan from these contaminants over the 6 week exposure period between the WTC attacks and sampling dates. Residents of lower Manhattan appear to have a slightly elevated cancer risk (up to 1.6% increase over background) and increased P(2378)CDD/F body burden (up to 8.0% increase over background) because of above-background exposure to high concentrations of P(2378)CDD/Fs produced from the WTC attacks during the short period between 11 September 2001, and window film sampling 6 weeks later.

Cutaneous exposure scenarios for engineered nanoparticles used in semiconductor fabrication: a preliminary investigation of workplace surface contamination

PubMed Central

Shepard, Michele; Brenner, Sara

2014-01-01

Background: Numerous studies are ongoing in the fields of nanotoxicology and exposure science; however, gaps remain in identifying and evaluating potential exposures from skin contact with engineered nanoparticles in occupational settings. Objectives: The aim of this study was to identify potential cutaneous exposure scenarios at a workplace using engineered nanoparticles (alumina, ceria, amorphous silica) and evaluate the presence of these materials on workplace surfaces. Methods: Process review, workplace observations, and preliminary surface sampling were conducted using microvacuum and wipe sample collection methods and transmission electron microscopy with elemental analysis. Results: Exposure scenarios were identified with potential for incidental contact. Nanoparticles of silica or silica and/or alumina agglomerates (or aggregates) were identified in surface samples from work areas where engineered nanoparticles were used or handled. Conclusions: Additional data are needed to evaluate occupational exposures from skin contact with engineered nanoparticles; precautionary measures should be used to minimize potential cutaneous exposures in the workplace. PMID:25000112

Mid-latitude trans-Pacific reconstructions and comparisons of coupled glacial/interglacial climate cycles based on soil stratigraphy of cover-beds

NASA Astrophysics Data System (ADS)

Alloway, B. V.; Almond, P. C.; Moreno, P. I.; Sagredo, E.; Kaplan, M. R.; Kubik, P. W.; Tonkin, P. J.

2018-06-01

South Westland, New Zealand, and southern Chile, are two narrow continental corridors effectively confined between the Pacific Ocean in the west and high mountain ranges in the east which impart significant influence over regional climate, vegetation and soils. In both these southern mid-latitude regions, evidence for extensive and repeated glaciations during cold phases of the Quaternary is manifested by arrays of successively older glacial drift deposits with corresponding outwash plain remnants. In South Westland, these variably aged glacial landforms are mantled by layered (multisequal) soils characterised by slow loess accretion and pedogenesis in an extreme leaching and weathering environment. These cover-bed successions have undergone repeated coupled phases of topdown and upbuilding soil formation that have been related to fluctuating cycles of interglacial/warm and glacial/cold climate during the Quaternary. In this study, we recognise multisequal soils overlying glacial landforms in southern continental Chile but, unlike the spodic (podzolic) soil sequences of South Westland, these are of dominantly volcanigenic (andic) provenance and are very similar to multisequal soils of andic provenance that predominate in, and adjacent to, areas of rhyolitic to andesitic volcanism in North Island, New Zealand. Here we develop a soil-stratigraphic model to explain the observed occurrence of multisequal soils mantling dominantly glacial landforms of southern continental Chile. Based on proxy data from southern Chile, we propose that persistent vegetation cover and high precipitation on the western side of the Andes, during colder-than-present episodes tended to suppress the widespread production of glacially-derived loessial materials despite the pervasive occurrence of glacial and glacio-fluvial deposits that have frequently inundated large tracts of this landscape during the Quaternary. Given the lack of loess cover-beds that have traditionally assisted in the relative dating of glacial episodes prior to the Late Quaternary, surface exposure dating techniques could provide another chronological alternative to address this issue. However, there have been two main obstacles to successfully apply this dating technique in Patagonia. First, minimum exposure ages may be obtained on moraines older than the last glacial cycle due to erosion, although dating outwash plains is more robust. Second, on the wet western side adjacent to the Andes, persistent vegetation cover during both glacial and post-glacial times, as well as widespread inundation by volcanic mass-flows, appear preventive. We make a case that soil genesis within this region appears to be dominated by a constant flux of intermittently erupted Andean-sourced tephra which has continued to upbuild soils at the ground surface separated by intervals where topdown weathering processes are intensified. As already demonstrated by New Zealand studies, multisequal soil successions have a clear implied connection to coupled glacial and interglacial climate cycles of the Quaternary. On this basis, similar sequences in northwest Patagonia provide a relatively untapped archive to enable Quaternary glacial and environmental changes in this pervasively glaciated volcanic region to be constructed.

Snežna jama (Slovenia): Interdisciplinary dating of cave sediments and implication for landscape evolution

PubMed Central

Häuselmann, Philipp; Mihevc, Andrej; Pruner, Petr; Horáček, Ivan; Čermák, Stanislav; Hercman, Helena; Sahy, Diana; Fiebig, Markus; Hajna, Nadja Zupan; Bosák, Pavel

2015-01-01

Caves are important markers of surface evolution, since they are, as a general rule, linked with ancient valley bottoms by their springs. However, caves can only be dated indirectly by means of the sediments they contain. If the sediment is older than common dating methods, one has to use multiple dating approaches in order to get meaningful results. U/Th dating, palaeomagnetic analysis of flowstone and sediment profiles, cosmogenic dating of quartz pebbles, and mammalian dating allowed a robust estimate of speleogenesis, sediment deposition, climatic change at the surface, and uplift history on the Periadriatic fault line during the Plio-Pleistocene. Our dates indicate that Snežna jama was formed in the (Upper) Miocene, received its sedimentary deposits during the Pliocene in a rather low-lying, hilly landscape, and became inactive due to uplift along the Periadriatic and Sava faults and climatic changes at the beginning of the Quaternary. Although it is only a single cave, the information contained within it makes it an important site of the Southern Alps. PMID:26516294

Snežna jama (Slovenia): Interdisciplinary dating of cave sediments and implication for landscape evolution.

PubMed

Häuselmann, Philipp; Mihevc, Andrej; Pruner, Petr; Horáček, Ivan; Čermák, Stanislav; Hercman, Helena; Sahy, Diana; Fiebig, Markus; Hajna, Nadja Zupan; Bosák, Pavel

2015-10-15

Caves are important markers of surface evolution, since they are, as a general rule, linked with ancient valley bottoms by their springs. However, caves can only be dated indirectly by means of the sediments they contain. If the sediment is older than common dating methods, one has to use multiple dating approaches in order to get meaningful results. U/Th dating, palaeomagnetic analysis of flowstone and sediment profiles, cosmogenic dating of quartz pebbles, and mammalian dating allowed a robust estimate of speleogenesis, sediment deposition, climatic change at the surface, and uplift history on the Periadriatic fault line during the Plio-Pleistocene. Our dates indicate that Snežna jama was formed in the (Upper) Miocene, received its sedimentary deposits during the Pliocene in a rather low-lying, hilly landscape, and became inactive due to uplift along the Periadriatic and Sava faults and climatic changes at the beginning of the Quaternary. Although it is only a single cave, the information contained within it makes it an important site of the Southern Alps.

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

King, Sean W., E-mail: sean.king@intel.com; Davis, Robert F.; Carter, Richard J.

The desorption kinetics of molecular hydrogen (H{sub 2}) from silicon (001) surfaces exposed to aqueous hydrogen fluoride and remote hydrogen plasmas were examined using temperature programmed desorption. Multiple H{sub 2} desorption states were observed and attributed to surface monohydride (SiH), di/trihydride (SiH{sub 2/3}), and hydroxide (SiOH) species, subsurface hydrogen trapped at defects, and hydrogen evolved during the desorption of surface oxides. The observed surface hydride species were dependent on the surface temperature during hydrogen plasma exposure with mono, di, and trihydride species being observed after low temperature exposure (150 °C), while predominantly monohydride species were observed after higher temperature exposure (450 °C).more » The ratio of surface versus subsurface H{sub 2} desorption was also found to be dependent on the substrate temperature with 150 °C remote hydrogen plasma exposure generally leading to more H{sub 2} evolved from subsurface states and 450 °C exposure leading to more H{sub 2} desorption from surface SiH{sub x} species. Additional surface desorption states were observed, which were attributed to H{sub 2} desorption from Si (111) facets formed as a result of surface etching by the remote hydrogen plasma or aqueous hydrogen fluoride treatment. The kinetics of surface H{sub 2} desorption were found to be in excellent agreement with prior investigations of silicon surfaces exposed to thermally generated atomic hydrogen.« less

Exposure to family violence and attachment styles as predictors of dating violence perpetration among men and women: a mediational model.

PubMed

Lee, Mary; Reese-Weber, Marla; Kahn, Jeffrey H

2014-01-01

This study examined a multiple mediator model explaining how sibling perpetration and one's attachment style mediate the relation between parent-to-child victimization and dating violence perpetration. A sample of undergraduate students (n = 392 women, n = 89 men) completed measures of the aforementioned variables on an Internet survey. For men, path analyses found no mediation; parent-to-child victimization had a direct association with dating violence perpetration, no association was found between sibling perpetration and dating violence perpetration, and attachment anxiety, but not attachment avoidance, was positively associated with dating violence perpetration for men. For women, the hypothesized mediation model was supported; parent-to-child victimization had a direct association with dating violence perpetration, and sibling perpetration and attachment anxiety served as mediating variables. Attachment avoidance was not associated with dating violence perpetration for women. Implications for future research and clinical practice are discussed.

The Schmidt hammer as a relative-age dating tool and its potential for calibrated-age dating in Holocene glaciated environments

NASA Astrophysics Data System (ADS)

Shakesby, Richard A.; Matthews, John A.; Owen, Geraint

2006-11-01

The Schmidt hammer is a relatively cheap, portable, sturdy instrument with proven value over the last two decades or so in rapidly dating coarse inorganic deposits of diverse origins. Early views were that its dating role was limited to distinguishing recently exposed from much older. Typically, either a few sites of possibly different ages or occasional older surfaces amongst many young sites were studied. More recently, calibration curves based on individual R-value means from small numbers (2-4) of sites of known ages have been used to estimate the ages of undated sites. We present Schmidt hammer rebound ( R-) values from 28 'Little Ice Age' (and younger), 23 Preboreal and 7 Younger Dryas glaciated surfaces in southern Norway in order, first, to test rigorously the robustness of the instrument as a relative-age dating tool. Despite being obtained from different surfaces (moraines, glaciofluvial deposits and bedrock) and varied metamorphic lithologies, the R-value overall means and 95% confidence intervals for the 'Little Ice Age', Preboreal and Younger Dryas age categories (respectively, 60.0±1.6, 41.6±1.4 and 34.2±2.0) are statistically significantly different. Only two outlying sites in the two younger age categories have overlapping confidence intervals, demonstrating remarkable robustness in differentiating early- and late-Holocene surfaces. The distinction between Preboreal and Younger Dryas sites (with terminal dates <2000 years apart) is less clear but still statistically significant, though possibly partly because of enhanced weathering conditions at the predominantly well vegetated Younger Dryas sites. Second, we examine the feasibility and desirability of controlling non-age-related factors, including some previously considered critical (instrument wear, operator bias, initial rock surface texture), which emerge either as less important than previously argued or as relatively unimportant, together with others previously unreported (e.g. long-term changes in lichen, soil, snow and vegetation covers). Third, we investigate the potential for calibrated-age dating by applying exploratory, linear rates of R-value decline to selected combinations of sites. The results suggest that error limits of ca ±700 to ±1600 years should be achievable over the Holocene timescale. This improved dating capability, however, will require adequate numbers of site means not only for each age category used to define these curves but also for each set of test surfaces of the same ages. Recommendations are made for a suitable sampling protocol for developing further the Schmidt hammer as a calibrated-age dating tool.

Pattern of dental caries experience on tooth surfaces in an adult population.

PubMed

Hopcraft, Matthew Scott; Morgan, Michael Vivian

2006-06-01

To determine the pattern of caries experience across teeth and surfaces in an adult population depending on age and exposure to water fluoridation. Between November 2002 and March 2003 a total of 973 subjects aged 17-51 years had a clinical examination using visual and tactile criteria. Subsequent to this examination, bitewing radiographs were taken and viewed separately. Approximal and occlusal surfaces of molars and premolars were examined on the radiographs. Caries experience was relatively low, with mean DMFS scores of 3.21, 5.12, 9.61, 13.04 and 24.35 for subjects aged 17-20, 21-25, 26-30, 31-35 and 36-51 years respectively. The first molar teeth had the greatest caries experience, and occlusal surfaces had more caries experience than approximal surfaces. Subjects with a lifetime exposure to fluoridated drinking water had significantly lower caries experience than those who had no exposure to fluoridated drinking water. This study showed that caries prevalence, although relatively low in the study population, was found predominantly in occlusal surfaces, with an increasing prevalence in approximal surfaces of posterior teeth in older subjects. Subjects with a lifetime exposure to fluoridated drinking water had a lower level of caries experience than those with no exposure to fluoridated drinking water, and this was more noticeable in approximal surfaces than occlusal surfaces.

Geochronological (OSL) and geomorphological investigations at the presumed Frankfurt ice marginal position in northeast Germany

NASA Astrophysics Data System (ADS)

Hardt, Jacob; Lüthgens, Christopher; Hebenstreit, Robert; Böse, Margot

2016-12-01

The Weichselian Frankfurt ice marginal position in northeast Germany has been critically discussed in the past owing to weak morphological evidence and a lack of clear sedimentological records. This study aims to contribute to this discussion with new geochronological and geomorphological results. Apart from very few cosmogenic exposure ages, the time frame is to date still based on long distance correlation with radiocarbon chronologies. We selected a study site in a key position regarding the classic location of the Frankfurt ice marginal position and the recently described arcuate ridge structures on the Barnim plateau. For the first time we present Optically Stimulated Luminescence (OSL) ages of quartz from glaciofluvial deposits for this Weichselian phase. Our results indicate an advance of the Scandinavian Ice Sheet (SIS) at around 34.1 ± 4.6 ka. This is in agreement with OSL ages from sandur deposits at the Brandenburg ice marginal position located farther south and could also be correlated with the Klintholm advance in Denmark. The subsequent meltdown phase lasted until around 26.3 ± 3.7 ka. During the meltdown phase a minor oscillation of the SIS caused the formation of the recently described arcuate ridges on the Barnim till plain. Recalculated surface exposure ages of glacigenic boulders with an updated global production rate indicate a landscape stabilization phase at around 22.7 ± 1.6 ka, which is in agreement with our ages. A phase of strong aeolian activity has been dated with OSL to 1 ± 0.1 ka; this may have been triggered by human activities that are documented in this region for the medieval period.

The Argon Geochronology Experiment (AGE)

NASA Technical Reports Server (NTRS)

Swindle, T. D.; Bode, R.; Fennema, A.; Chutjian, A.; MacAskill, J. A.; Darrach, M. R.; Clegg, S. M.; Wiens, R. C.; Cremers, D.

2006-01-01

This viewgraph presentation reviews the Argon Geochronology Experiment (AGE). Potassium-Argon dating is shown along with cosmic ray dating exposure. The contents include a flow diagram of the Argon Geochronology Experiment, and schematic diagrams of the mass spectrometer vacuum system, sample manipulation mechanism, mineral heater oven, and the quadrupole ion trap mass spectrometer. The Laser-Induced Breakdown Spectroscopy (LIBS) Operation with elemental abundances is also described.

Epidemiology of Health Effects of Radiofrequency Exposure

PubMed Central

Ahlbom, Anders; Green, Adele; Kheifets, Leeka; Savitz, David; Swerdlow, Anthony

2004-01-01

We have undertaken a comprehensive review of epidemiologic studies about the effects of radiofrequency fields (RFs) on human health in order to summarize the current state of knowledge, explain the methodologic issues that are involved, and aid in the planning of future studies. There have been a large number of occupational studies over several decades, particularly on cancer, cardiovascular disease, adverse reproductive outcome, and cataract, in relation to RF exposure. More recently, there have been studies of residential exposure, mainly from radio and television transmitters, and especially focusing on leukemia. There have also been studies of mobile telephone users, particularly on brain tumors and less often on other cancers and on symptoms. Results of these studies to date give no consistent or convincing evidence of a causal relation between RF exposure and any adverse health effect. On the other hand, the studies have too many deficiencies to rule out an association. A key concern across all studies is the quality of assessment of RF exposure. Despite the ubiquity of new technologies using RFs, little is known about population exposure from RF sources and even less about the relative importance of different sources. Other cautions are that mobile phone studies to date have been able to address only relatively short lag periods, that almost no data are available on the consequences of childhood exposure, and that published data largely concentrate on a small number of outcomes, especially brain tumor and leukemia. PMID:15579422

Thermal Interaction of Contact Lens Eyewear and 94 GHz Ocular Exposures

DTIC Science & Technology

2008-09-01

AFRL-RH-BR-TR-2008-0071 ` Thermal Interaction of Contact Lens Eyewear and 94 GHz Ocular Exposures John D’Andrea Carrie C. Crane...THERMAL INTERACTION OF CONTACT LENS EYEWEAR AND 94 GHz OCULAR EXPOSURES D’Andrea JA 1, Crane CC1, Hatcher DJ1, Marchello DR1, Ziriax JM1...MM-YYYY) 12-20-2005 2. REPORT TYPE Technical Report 3. DATES COVERED (From - To) 2004-2005 THERMAL INTERACTION OF CONTACT LENS EYEWEAR AND 94

Visual Inspection of Surfaces

NASA Technical Reports Server (NTRS)

Hughes, David; Perez, Xavier

2007-01-01

This presentation evaluates the parameters that affect visual inspection of cleanliness. Factors tested include surface reflectance, surface roughness, size of the largest particle, exposure time, inspector and distance from sample surface. It is concluded that distance predictions were not great, particularly because the distance at which contamination is seen may depend on more variables than those tested. Most parameters estimates had confidence of 95% or better, except for exposure and reflectance. Additionally, the distance at which surface is visibly contaminated decreases with increasing reflectance, roughness, and exposure. The distance at which the surface is visually contaminated increased with the largest particle size. These variables were only slightly affected the observer.

Aviation-attributable ozone as a driver for changes in mortality related to air quality and skin cancer

NASA Astrophysics Data System (ADS)

Eastham, Sebastian D.; Barrett, Steven R. H.

2016-11-01

Aviation is a significant source of tropospheric ozone, which is a critical UV blocking agent, an indirect precursor to the formation of particulate matter, and a respiratory health hazard. To date, investigations of human health impacts related to aviation emissions have focused on particulate matter, and no global estimate yet exists of the combined health impact of aviation due to ozone, particulate matter and UV exposure changes. We use a coupled tropospheric-stratospheric chemical-transport model with a global aviation emissions inventory to estimate the total impact of aviation on all three risk factors. We find that surface ozone due to aviation emissions is maximized during hemispheric winter due to the greater wintertime chemical lifetime of ozone, but that a smaller enhancement of 0.5 ppbv occurs during summertime. This summertime increase results in an estimated 6,800 premature mortalities per year due to ozone exposure, over three times greater than previous estimates. During the winter maximum, interaction with high background NOx concentrations results in enhanced production of nitrate aerosol and increased annual average exposure to particulate matter. This ozone perturbation is shown to be the driving mechanism behind an additional 9,200 premature mortalities due to exposure to particulate matter. However, the increase in tropospheric ozone is also found to result in 400 fewer mortalities due to melanoma skin cancer in 2006. This is the first estimate of global melanoma mortality due to aviation, and the first estimate of skin cancer mortality impacts due to aviation using a global chemical transport model.

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

NASA Astrophysics Data System (ADS)

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

2016-12-01

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

Development of a second-generation novel UVR sensor for the quantification of the light field at the anterior ocular surface

NASA Astrophysics Data System (ADS)

Fleming, David; Walsh, James E.; Moore, Linda; Bergmanson, Jan P. G.; McMahon, David

2005-06-01

Research has shown in recent years that acute and cumulative exposure to excessive ultraviolet radiation (UVR) can cause a range of degenerative ocular conditions such as pterygium, photokeratitis and pinguecula. The increase in natural solar UVR as a result of the depletion of the ozone layer has led to a greater awareness of the adverse effects of UVR on the anterior ocular surface tissues. The relevance of this lies in the fact that these tissues are not immune to photodamage and that there is selective absorption of UVR by conjunctival and corneal tissue in the anterior ocular surface. Therefore, there is a demand for more precise quantification and localisation of UVR incidence at the anterior ocular surface. A novel solar blind photodiode sensor array has been designed, constructed and tested for this purpose. The emphasis of the measurements made by this sensor system is the acquisition of real time, field based surveys of the ocular UVR light field in a broad range of insolation environments. These data will then provide a thorough database of UVR irradiances that can be related to induced damage of anterior ocular tissue. Results to date show the first measured, in-vivo, absolute UVR levels on the eye, the corresponding relative field across the eye and the presence of nasal-temporal biases that exist.

[Evaluation of the occupational risk related to exposure to electromagnetic fields according to the EC Directive 2004/40 EC: exposure during pregnancy].

PubMed

Gobba, F; Tavani, M; Bianchi, N

2007-01-01

The EU Directive 2004/40/EC on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (electromagnetic fields) will introduce the need of an evaluation of the risk related to EMF occupational exposure in pregnancy. Nevertheless, data from research in this field are scarcely conclusive to date. Furthermore knowledge on this risk seems insufficient among OH physicians in Italy. Accordingly, there is an urgent need for further research, and for a diffusion of knowledge among OH physicians on possible risk to pregnancy due to occupational exposure to EMF.

Episodic bedrock erosion by gully-head migration, Colorado High Plains, USA

USGS Publications Warehouse

Rengers, Francis K.; Tucker, G.E.; Mahan, Shannon

2016-01-01

This study explores the frequency of bedrock exposure in a soil-mantled low-relief (i.e. non-mountainous) landscape. In the High Plains of eastern Colorado, gully headcuts are among the few erosional features that will incise through the soil mantle to expose bedrock. We measured the last time of bedrock exposure using optically stimulated luminescence dating of alluvial sediment overlying bedrock in gully headcuts. Our dating suggests that headcuts in adjacent gullies expose bedrock asynchronously, and therefore, the headcuts are unlikely to have been triggered by a base-level drop in the trunk stream. This finding supports the hypothesis that headcuts can develop locally in gullies as a result of focused scour in locations where hydraulic stress during a flash flood is sufficiently high, and/or ground cover is sufficiently weak, to generate a scour hole that undermines vegetation. Alluvium dating also reveals that gullies have been a persistent part of this landscape since the early Holocene. 

Cyber dating abuse among teens using school-based health centers.

PubMed

Dick, Rebecca N; McCauley, Heather L; Jones, Kelley A; Tancredi, Daniel J; Goldstein, Sandi; Blackburn, Samantha; Monasterio, Erica; James, Lisa; Silverman, Jay G; Miller, Elizabeth

2014-12-01

To estimate the prevalence of cyber dating abuse among youth aged 14 to 19 years seeking care at school-based health centers and associations with other forms of adolescent relationship abuse (ARA), sexual violence, and reproductive and sexual health indicators. A cross-sectional survey was conducted during the 2012-2013 school year (participant n = 1008). Associations between cyber dating abuse and study outcomes were assessed via logistic regression models for clustered survey data. Past 3-month cyber dating abuse was reported by 41.4% of this clinic-based sample. More female than male participants reported cyber dating abuse victimization (44.6% vs 31.0%). Compared with no exposure, low- ("a few times") and high-frequency ("once or twice a month" or more) cyber dating abuse were significantly associated with physical or sexual ARA (low: adjusted odds ratio [aOR] 2.8, 95% confidence interval [CI] 1.8-4.4; high: aOR 5.4, 95% CI 4.0-7.5) and nonpartner sexual assault (low: aOR 2.7, 95% CI 1.3-5.5; high: aOR 4.1, 95% CI 2.8-5.9). Analysis with female participants found an association between cyber dating abuse exposure and contraceptive nonuse (low: aOR 1.8, 95% CI 1.2-2.7; high: aOR 4.1, 95% CI 2.0-8.4) and reproductive coercion (low: aOR 3.0, 95% CI 1.4-6.2; high: aOR 5.7, 95% CI 2.8-11.6). Cyber dating abuse is common and associated with ARA and sexual assault in an adolescent clinic-based sample. The associations of cyber dating abuse with sexual behavior and pregnancy risk behaviors suggest a need to integrate ARA education and harm reduction counseling into sexual health assessments in clinical settings. Copyright © 2014 by the American Academy of Pediatrics.

Current activities and results of the Long Duration Exposure Facility Meteoroid and Debris Special Investigation Group

NASA Astrophysics Data System (ADS)

See, Thomas H.; Leago, Kimberly S.; Warren, Jack L.; Bernhard, Ronald P.; Zolensky, Michael E.

1994-03-01

Fiscal Year 1994 will bring to a close the initial investigative activities associated with the Long Duration Exposure Facility (LDEF). LDEF was a 14-faced spacecraft (i.e., 12-sided cylinder and two ends) which housed 54 different experimental packages in low-Earth orbit (LEO) from Apr. 1984 to Jan. 1990 (i.e., for approx. 5.75 years). Since LDEF's return, the Meteoroid & Debris Special Investigation Group (M&D SIG) has been examining various LDEF components in order to better understand and define the LEO particulate environment. Members of the M&D SIG at JSC in Houston, TX have been contributing to these studies by carefully examining and documenting all impact events found on LDEF's 6061-T6 aluminum Intercostals (i.e., one of the spacecraft's structural frame components). Unlike all other hardware on LDEF, the frame exposed significantly large surface areas of a single homogeneous material in all (i.e., 26) possible LDEF pointing directions. To date, 28 of the 68 Intercostals in the possession of the M&D SIG have been documented. This data, as well as similar information from various LDEF investigators, can be accessed through the M&D SIG Database which is maintained at JSC.

Current activities and results of the Long Duration Exposure Facility Meteoroid and Debris Special Investigation Group

NASA Technical Reports Server (NTRS)

See, Thomas H.; Leago, Kimberly S.; Warren, Jack L.; Bernhard, Ronald P.; Zolensky, Michael E.

1994-01-01

Fiscal Year 1994 will bring to a close the initial investigative activities associated with the Long Duration Exposure Facility (LDEF). LDEF was a 14-faced spacecraft (i.e., 12-sided cylinder and two ends) which housed 54 different experimental packages in low-Earth orbit (LEO) from Apr. 1984 to Jan. 1990 (i.e., for approx. 5.75 years). Since LDEF's return, the Meteoroid & Debris Special Investigation Group (M&D SIG) has been examining various LDEF components in order to better understand and define the LEO particulate environment. Members of the M&D SIG at JSC in Houston, TX have been contributing to these studies by carefully examining and documenting all impact events found on LDEF's 6061-T6 aluminum Intercostals (i.e., one of the spacecraft's structural frame components). Unlike all other hardware on LDEF, the frame exposed significantly large surface areas of a single homogeneous material in all (i.e., 26) possible LDEF pointing directions. To date, 28 of the 68 Intercostals in the possession of the M&D SIG have been documented. This data, as well as similar information from various LDEF investigators, can be accessed through the M&D SIG Database which is maintained at JSC.

The deglacial history of NW Alexander Island, Antarctica, from surface exposure dating

NASA Astrophysics Data System (ADS)

Johnson, Joanne S.; Everest, Jeremy D.; Leat, Philip T.; Golledge, Nicholas R.; Rood, Dylan H.; Stuart, Finlay M.

2012-03-01

Recent changes along the margins of the Antarctic Peninsula, such as the collapse of the Wilkins Ice Shelf, have highlighted the effects of climatic warming on the Antarctic Peninsula Ice Sheet (APIS). However, such changes must be viewed in a long-term (millennial-scale) context if we are to understand their significance for future stability of the Antarctic ice sheets. To address this, we present nine new cosmogenic 10Be exposure ages from sites on NW Alexander Island and Rothschild Island (adjacent to the Wilkins Ice Shelf) that provide constraints on the timing of thinning of the Alexander Island ice cap since the last glacial maximum. All but one of the 10Be ages are in the range 10.2-21.7 ka, showing a general trend of progressive ice-sheet thinning since at least 22 ka until 10 ka. The data also provide a minimum estimate (490 m) for ice-cap thickness on NW Alexander Island at the last glacial maximum. Cosmogenic 3He ages from a rare occurrence of mantle xenoliths on Rothschild Island yield variable ages up to 46 ka, probably reflecting exhumation by periglacial processes.

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

Deino, A.; Potts, R.

Single-crystal laser fusion {sup 40}Ar/{sup 39}Ar analyses and several conventional bulk fusion {sup 40}K- {sup 40}Ar dates have been used to determine the age of volcaniclastic strata within the Olorgesailie Formation and of associated volcanic and sedimentary units of the southern Kenya rift. In the principal exposures along the southern edge of the Legemunge Plain, the formation spans the interval from approximately 500 to 1,000 ka. Deposition continued to the east along the Ol Keju Nyiro river where a tuff near the top of the formation has been dated at 215 ka. In these exposures, the formation is unconformably overlainmore » by sediments dated at 49 ka. A possible source for the Olorgesailie tephra, the Ol Doinyo Nyokie volcanic complex, contains as ash flow dated at {approximately} 1 Ma, extending the known age range of this complex to encompass that of virtually the entire Olorgesailie Formation in the Legemunge Plain. These geologic examples illustrate the importance of the single-crystal {sup 40}Ar/{sup 39}Ar dating technique whereby contaminant, altered, or otherwise aberrant grains can be identified and eliminated from the determination of eruptive ages for reworked or altered pyroclastic deposits. The authors have presented a computer-modeling procedure based on an inverse-isochron analysis that promotes a more objective approach to trimming {sup 40}Ar/{sup 39}Ar isotope data sets of this type.« less

Determination of heavy metals in the fruit of date palm growing at different locations of Riyadh

PubMed Central

Aldjain, Ibrahim M.; Al-Whaibi, Mohamed H.; Al-Showiman, Salim S.; Siddiqui, Manzer H.

2010-01-01

Exposure of heavy metals to human beings has risen dramatically in the last 50 years. In today’s urban and industrial society, there is no escaping from exposure to toxic chemicals and heavy metals. Humans are more likely to be exposed to heavy metal contamination from the dust that adheres to edible plants than from bioaccumulation. This is because it is very difficult to wash off all the dust particles from the plant material before ingesting them. The objectives of this experiment were to determine the concentrations of lead (Pb) and cadmium (Cd) in washing residues and in the tissues of fruits of date palm growing in 14 sites of Riyadh and also to assess whether the fruits were safe for human consumption. The washing residues and tissue of date palm fruits collected from different sites showed the presence of significant amounts of the Pb and Cd. The concentration of Pb in the dust and fruit tissue increased with increasing anthropogenic sources. Therefore, fruits of date palm might be used as a pollution indicator; it might be recommend that fruits of date palm could be safe for human consumption after washing. The mean concentration of Pb and Cd in all the samples collected from different sites is within the safe limits recommended by FAO/WHO. PMID:23961121

PESTICIDE RESIDUE RECOVERIES FROM SURFACE WIPES

EPA Science Inventory

Human exposure is a consequence of pesticide use indoors with a primary source resulting from residue deposition on household surfaces. Accurate measurements of surface residues is essential for estimating exposure from different routes. Various procedures have been developed ...

Developmental effects of 3,4-methylenedioxymethamphetamine: a review.

PubMed

Skelton, Matthew R; Williams, Michael T; Vorhees, Charles V

2008-03-01

+/-3,4-Methylenedioxymethamphetamine (MDMA) is a chemical derivative of amphetamine that has become a popular drug of abuse and has been shown to deplete serotonin in the brains of users and animals exposed to it. To date, most studies have investigated the effects of MDMA on adult animals. With a majority of users of MDMA being young adults, the chances of the users becoming pregnant and exposing the fetuses to MDMA are also a concern. Evidence to date has shown that developmental exposure to MDMA results in learning and memory impairments in the Morris water maze, a task known to be sensitive to hippocampal disruption, when the animals are tested as adults. Developmental MDMA exposure leads to hypoactivity in the offspring as adults but does not affect outcome on tests of anxiety. MDMA administration decreases pup weight, increases corticosterone and brain-derived neurotrophic factor levels during treatment while decreasing brain levels of serotonin; a decrease that initially dissipates and then reappears in adulthood. Neonatal MDMA exposure increases the sensitivity of the serotonin 1A receptor, a possible mechanism underlying the learning and memory deficits seen. Taken together, the evidence shows that MDMA exposure has adverse effects on the developing brain and behavior. The animal and human data on developmental MDMA exposure are reviewed and their public health implications discussed.

Disease fatality and bias in survival cohorts.

PubMed

Barry, Vaughn; Klein, Mitchel; Winquist, Andrea; Darrow, Lyndsey A; Steenland, Kyle

2015-07-01

Simulate how the effect of exposure on disease occurrence and fatality influences the presence and magnitude of bias in survivor cohorts, motivated by an actual survivor cohort under study. We simulated a cohort of 50,000 subjects exposed to a disease-causing exposure over time and followed forty years, where disease incidence was the outcome of interest. We simulated this 'inception' cohort under different assumptions about the effect of exposure on disease occurrence and fatality after disease occurrence. We then created a corresponding 'survivor' (or 'cross-sectional') cohort, where cohort enrollment took place at a specific date after exposure began in the inception cohort; subjects dying prior to that enrollment date were excluded. The disease of interest caused all deaths in our simulations, but was not always fatal. In the survivor cohort, person-time at risk began before enrollment for all subjects who did not die prior to enrollment. We compared exposure-disease associations in each inception cohort to those in corresponding survivor cohorts to determine how different assumptions impacted bias in the survivor cohorts. All subjects in both inception and survivor cohorts were considered equally susceptible to the effect of exposure in causing disease. We used Cox proportional hazards regression to calculate effect measures. There was no bias in survivor cohort estimates when case fatality among diseased subjects was independent of exposure. This was true even when the disease was highly fatal and more highly exposed subjects were more likely to develop disease and die. Assuming a positive exposure-response in the inception cohort, survivor cohort rate ratios were biased downwards when case fatality was greater with higher exposure. Survivor cohort effect estimates for fatal outcomes are not always biased, although precision can decrease. Copyright © 2015 Elsevier Inc. All rights reserved.

ISSUES IN UNDERSTANDING DERMAL EXPOSURES RESULTING FROM CONTACT WITH CONTAMINATED SURFACES, MEASURING SURFACE CONTAMINATION, AND CHARACTERIZING TRANSFERS

EPA Science Inventory

Although monitoring for surface contamination in work with radioactive materials and dermal monitoring of pesticide exposure to agricultural workers have been standard practice for 50 years, regular surface sampling and dermal monitoring methods have only been applied to indust...

TRANSFER OF PESTICIDES FROM SURFACES TO FOODS FOR THE ESTIMATION OF DIETARY EXPOSURE OF CHILDREN

EPA Science Inventory

Since small children spend much of their time in contact with contaminated surfaces, residues of pesticides found on floors and other surfaces contribute to their aggregate exposures. Any dislodgeable pesticide residues on hands and surfaces may be transferred to foods while bei...

Timing and nature of Holocene glacier advances at the northwestern end of the Himalayan-Tibetan orogen

NASA Astrophysics Data System (ADS)

Saha, Sourav; Owen, Lewis A.; Orr, Elizabeth N.; Caffee, Marc W.

2018-05-01

Holocene glacial chronostratigraphies are developed for four glaciated valleys at the northwestern end of the Himalayan-Tibetan orogen using geomorphic mapping and cosmogenic 10Be surface exposure dating. The study areas include the Hamtah valley in the Lahul Himalaya, and the Karzok, Lato and upper Stok valleys in Zanskar. Five local glacial stages are dated to ∼10.4, ∼6.1-3.3, ∼2.1-0.9, ∼0.7-0.4, and ∼0.3-0.2 ka based on 49 new moraine boulder ages. Large age dispersions are evident for each of the local glacial stages. This is especially the case for ∼6.1-3.3 and ∼2.1-0.9 ka, which is likely a result of prior and/or incomplete exposures in very young moraine boulders. An additional compilation of 187 published 10Be moraine boulder ages help define seven Himalayan Holocene regional glacial stages (HHs) for the northwestern end of the Himalayan-Tibetan orogen. These HHs date to ∼10.9-9.3, ∼8.2-7.4, ∼6.9-4.3, ∼4.5-2.8, ∼2.7-1.8, ∼1.8-0.9, and <1 ka. Early Holocene glacier advances were generally more extensive and had larger equilibrium-line altitude depressions (ΔELA = ∼425 ± 229 m) than glacier advances during the mid-Holocene (ΔELA = ∼141 ± 106) and late Holocene (ΔELA = ∼124 ± 121 m). The early Holocene glacier advances likely correspond to orbitally-forced northerly migration of the Intertropical Convergence Zone and enhanced summer monsoon. The timing of the majority of HHs during mid- and late Holocene corresponds well with the North Atlantic cooling that is likely teleconnected via mid-latitude westerlies, particularly during ∼8 ka and after ∼5 ka. These chronostratigraphies suggest that Holocene glaciation in the northwestern part of the Himalayan-Tibetan orogen is largely influenced by long-term orbital forcing amplified by large-scale migration of the Earth's thermal equator and the associated hemispheric oceanic-atmospheric systems.

Timing of lake-level changes for a deep last-glacial Lake Missoula: optical dating of the Garden Gulch area, Montana, USA

NASA Astrophysics Data System (ADS)

Smith, Larry N.; Sohbati, Reza; Buylaert, Jan-Pieter; Lian, Olav B.; Murray, Andrew; Jain, Mayank

2018-03-01

Glaciolacustrine sediments in the Clark Fork River valley at Garden Gulch, near Drummond, Montana, USA record highstand positions of the ice-dammed glacial Lake Missoula and repeated subaerial exposure. During these highstands the lake was at greater than 65% of its recognized maximum capacity. The initial lake transgression deposited a basal sand unit. Subsequent cycles of lake-level fluctuations are recorded by sequences of laminated and cross laminated silt, sand, and clay deformed by periglacial processes during intervening periods of lower lake levels. Optically stimulated luminescence (OSL) dating of quartz sand grains, using single-aliquot regenerative-dose procedures, was carried out on 17 samples. Comparison of infrared stimulated luminescence (IRSL) from K-rich feldspar to OSL from quartz for all the samples suggests that they were well bleached prior to deposition and burial. Ages for the basal sand and overlying glaciolacustrine exposure surfaces are indistinguishable within one standard deviation, and give a weighted mean age of 20.9 ± 1.3 ka (n = 11). Based on sedimentological and stratigraphic analysis we infer that the initial transgression, and at least six cycles of lake-level fluctuation, occurred over time scales of decades to ∼2 ka. Bioturbated sandy slopewash dated at 10.6 ± 0.9 ka and 11.9 ± 1.2 ka unconformably overlies the upper glaciolacustrine deposits. The uppermost sediments, above the glaciolacustrine section, are younger than the Glacier Peak tephra (13.7-13.4 cal ka B.P.), which was deposited across parts of the drained lake basin, but has not been found at Garden Gulch. Our study indicates that glacial Lake Missoula reached >65 percent of maximum capacity by about 20.9 ± 1.3 ka and either partially or completely drained twelve times from this position. Rapid lowering from the lake's highstand position due to ice-dam failure likely led to scour in the downstream portions of the glacial Lake Missoula basin and megafloods in the Channeled Scabland.

Effect of high-flux H/He plasma exposure on tungsten damage due to transient heat loads

NASA Astrophysics Data System (ADS)

De Temmerman, G.; Morgan, T. W.; van Eden, G. G.; de Kruif, T.; Wirtz, M.; Matejicek, J.; Chraska, T.; Pitts, R. A.; Wright, G. M.

2015-08-01

The thermal shock behaviour of tungsten exposed to high-flux plasma is studied using a high-power laser. The cases of laser-only, sequential laser and hydrogen (H) plasma and simultaneous laser plus H plasma exposure are studied. H plasma exposure leads to an embrittlement of the material and the appearance of a crack network originating from the centre of the laser spot. Under simultaneous loading, significant surface melting is observed. In general, H plasma exposure lowers the heat flux parameter (FHF) for the onset of surface melting by ∼25%. In the case of He-modified (fuzzy) surfaces, strong surface deformations are observed already after 1000 laser pulses at moderate FHF = 19 MJ m-2 s-1/2, and a dense network of fine cracks is observed. These results indicate that high-fluence ITER-like plasma exposure influences the thermal shock properties of tungsten, lowering the permissible transient energy density beyond which macroscopic surface modifications begin to occur.

The dynamics of methicillin-resistant Staphylococcus aureus exposure in a hospital model and the potential for environmental intervention.

PubMed

Plipat, Nottasorn; Spicknall, Ian H; Koopman, James S; Eisenberg, Joseph Ns

2013-12-17

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of healthcare-associated infections. An important control strategy is hand hygiene; however, non-compliance has been a major problem in healthcare settings. Furthermore, modeling studies have suggested that the law of diminishing return applies to hand hygiene. Other additional control strategies such as environmental cleaning may be warranted, given that MRSA-positive individuals constantly shed contaminated desquamated skin particles to the environment. We constructed and analyzed a deterministic environmental compartmental model of MRSA fate, transport, and exposure between two hypothetical hospital rooms: one with a colonized patient, shedding MRSA; another with an uncolonized patient, susceptible to exposure. Healthcare workers (HCWs), acting solely as vectors, spread MRSA from one patient room to the other. Although porous surfaces became highly contaminated, their low transfer efficiency limited the exposure dose to HCWs and the uncolonized patient. Conversely, the high transfer efficiency of nonporous surfaces allows greater MRSA transfer when touched. In the colonized patient's room, HCW exposure occurred more predominantly through the indirect (patient to surfaces to HCW) mode compared to the direct (patient to HCW) mode. In contrast, in the uncolonized patient's room, patient exposure was more predominant in the direct (HCW to patient) mode compared to the indirect (HCW to surfaces to patient) mode. Surface wiping decreased MRSA exposure to the uncolonized patient more than daily surface decontamination. This was because wiping allowed higher cleaning frequency and cleaned more total surface area per day. Environmental cleaning should be considered as an integral component of MRSA infection control in hospitals. Given the previously under-appreciated role of surface contamination in MRSA transmission, this intervention mode can contribute to an effective multiple barrier approach in concert with hand hygiene.

Radiation exposure in the moon environment

NASA Astrophysics Data System (ADS)

Reitz, Guenther; Berger, Thomas; Matthiae, Daniel

2012-12-01

During a stay on the moon humans are exposed to elevated radiation levels due to the lack of substantial atmospheric and magnetic shielding compared to the Earth's surface. The absence of magnetic and atmospheric shielding allows cosmic rays of all energies to impinge on the lunar surface. Beside the continuous exposure to galactic cosmic rays (GCR), which increases the risk of cancer mortality, exposure through particles emitted in sudden nonpredictable solar particle events (SPE) may occur. SPEs show an enormous variability in particle flux and energy spectra and have the potential to expose space crew to life threatening doses. On Earth, the contribution to the annual terrestrial dose of natural ionizing radiation of 2.4 mSv by cosmic radiation is about 1/6, whereas the annual exposure caused by GCR on the lunar surface is roughly 380 mSv (solar minimum) and 110 mSv (solar maximum). The analysis of worst case scenarios has indicated that SPE may lead to an exposure of about 1 Sv. The only efficient measure to reduce radiation exposure is the provision of radiation shelters. Measurements on the lunar surface performed during the Apollo missions cover only a small energy band for thermal neutrons and are not sufficient to estimate the exposure. Very recently some data were added by the Radiation Dose Monitoring (RADOM) instrument operated during the Indian Chandrayaan Mission and the Cosmic Ray Telescope (CRaTER) instrument of the NASA LRO (Lunar Reconnaisance Orbiter) mission. These measurements need to be complemented by surface measurements. Models and simulations that exist describe the approximate radiation exposure in space and on the lunar surface. The knowledge on the radiation exposure at the lunar surface is exclusively based on calculations applying radiation transport codes in combination with environmental models. Own calculations are presented using Monte-Carlo simulations to calculate the radiation environment on the moon and organ doses on the surface of the moon for an astronaut in an EVA suit and are compared with measurements. Since it is necessary to verify/validate such calculations with measurement on the lunar surface, a description is given of a radiation detector for future detailed surface measurements. This device is proposed for the ESA Lunar Lander Mission and is capable to characterize the radiation field concerning particle fluencies, dose rates and energy transfer spectra for ionizing particles and to measure the dose contribution of secondary neutrons.

Radiation Shielding Optimization on Mars

NASA Technical Reports Server (NTRS)

Slaba, Tony C.; Mertens, Chris J.; Blattnig, Steve R.

2013-01-01

Future space missions to Mars will require radiation shielding to be optimized for deep space transit and an extended stay on the surface. In deep space, increased shielding levels and material optimization will reduce the exposure from most solar particle events (SPE) but are less effective at shielding against galactic cosmic rays (GCR). On the surface, the shielding provided by the Martian atmosphere greatly reduces the exposure from most SPE, and long-term GCR exposure is a primary concern. Previous work has shown that in deep space, additional shielding of common materials such as aluminum or polyethylene does not significantly reduce the GCR exposure. In this work, it is shown that on the Martian surface, almost any amount of aluminum shielding increases exposure levels for humans. The increased exposure levels are attributed to neutron production in the shield and Martian regolith as well as the electromagnetic cascade induced in the Martian atmosphere. This result is significant for optimization of vehicle and shield designs intended for the surface of Mars.

Relative effects of pre- and post-eruption water fluoride on caries experience by surface type of permanent first molars.

PubMed

Singh, Kiran A; Spencer, A John

2004-12-01

To determine the relative pre- and post-eruption exposure effects of fluoridated water on the caries experience of different surface types of first permanent molars. Parental questionnaires covering residential history of participants were linked to the oral examinations of 6-15-year-old Australian children conducted in 1992 by the School Dental Services of South Australia and Queensland. Percentage of lifetime exposed to optimally fluoridated water pre- (PRE) and post-eruption (POST) was calculated with respect to tooth eruption age. Combined pre- and post-eruption categories were created to test PRE against POST exposure: PRE and POST = 0, PRE < POST, PRE = POST and in the range 0-90% of lifetime exposure, PRE > POST and, PRE and POST >or= 90% lifetime exposure. These categories were used as indicator variables in linear regression models with PRE and POST = 0 as reference in an analysis of first permanent molar DMFS scores overall and by surface type. Participation rates were 69.7% in South Australia (n = 9690) and 55.6% in Queensland (n = 10 195). Compared with the reference, the categories PRE > POST (beta = -0.033), PRE = POST (beta = -0.028) in the range 0-90% and, PRE and POST >or= 90% (beta = -0.055) showed significantly lower caries overall (P < 0.01), with a similar pattern for pit and fissure surface caries (beta = -0.035, -0.031 and -0.052, respectively). Only a high PRE and POST exposure decreased caries levels significantly in the approximal (beta = -0.038; P < 0.01) and free smooth surfaces (beta = -0.023; P = 0.03). Pre-eruption exposure was important for a caries preventive effect on first permanent molars in children 6-15 years old since post-eruption exposure alone could not lower caries levels significantly. For pit and fissure surfaces, a high pre-eruption exposure could decrease caries levels significantly. However, for other surface types, only a high pre- and post-eruption exposure produced a caries preventive effect.

Luminescence Dating of Martian Polar Deposits: Concepts and Preliminary Measurements Using Martian Soil Analogs

NASA Astrophysics Data System (ADS)

Lepper, K.; Kuhns, C. K.; McKeever, S. W. S.; Sears, D. W. G.

2000-08-01

Martian polar deposits have the potential to reveal a wealth of information about the evolution of Mars' climate and surface environment. However, as pointed out by Clifford et al. in the summary of the First International Conference on Mars Polar Science and Exploration, 'The single greatest obstacle to unlocking and interpreting the geologic and climatic record preserved at the [martian] poles is the need for absolute dating.' At that same conference Lepper and McKeever proposed development of luminescence dating as a remote in-situ technique for absolute dating of silicate mineral grains incorporated in polar deposits. Clifford et al. have also acknowledged that luminescence dating is more practical from cost, engineering, and logistical perspectives than other isotope-based methods proposed for in-situ dating on Mars. We report here the results of ongoing experiments with terrestrial analogs of martian surface materials to establish a broad fundamental knowledge base from which robust dating procedures for robotic missions may be developed. This broad knowledge base will also be critical in determining the engineering requirements of remote in-situ luminescence dating equipment intended for use on Mars. Additional information can be found in the original extended abstract.

About the Exposure Factors Program | Science Inventory | US ...

EPA Pesticide Factsheets

The development of the latest version of the Exposure Factors Handbook (EFH): 2011 Edition (EPA/600/R-09/052F) has maintained the need for a more comprehensive program that addresses issues related to exposure factors. Since the first version of the EFH was released in 1997, the need for the most up-to-date and accurate data on exposure factors used in assessing exposure to contaminants in the environment is of high priority to exposure assessors throughout the U.S. The completion of the 2011 edition of the Exposure Factors Handbook has only been the first step in fulfilling this need. Many data needs have been identified and follow up research is underway to address some of the data gaps. This web page is intended to provide a

Multiple nuclide cosmogenic dating of very old desert pavements on the Puna Plateau, Northwest Argentina

NASA Astrophysics Data System (ADS)

Dortch, J.; Schoenbohm, L. M.

2011-12-01

Wind erosion of bedrock has been suggested to be responsible for the removal of more than 800 m of strata in the Qaidam Basin while wind deposition creates large-scale landforms such as the loess plateau. Wind eroded landforms, such as desert pavements in the Namibian Desert, Africa, form relic landscapes that are stable for more than 5 Ma. Desert pavements are of particular importance because of their widespread occurrence on terraces and fans, in mountains and coastal areas, and in hot and cold deserts including: Southwestern Africa, Antartic Dry valleys, Southwest USA, Denmark, Ireland, Israel, Sweden, and Central Tibet. Moreover, greater than 95 % of ventifacts on desert pavements are suspected to be late Quaternary to Holocene in age and are located on surfaces suitable for cosmogenic radionuclide dating. In spite of this, glacial, fluvial, and mass wasting systems have received far more attention than wind as an important geomorphic agent of erosion, deposition, and rock mass redistribution. Our goal is to: 1) quantify bedrock wind erosion rates; 2) quantify the ages of old, stable desert pavements; 3) and to identify which lithology-isotope pair provides the most accurate exposure ages for desert pavements in arid landscapes. The Puna Plateau, Argentina, is an ideal area to undertake this study because numerous wind eroded/deposited landforms are present, rates of fluvial erosion are low, and glaciation is limited. Mapping using remote sensed images shows that a significant portion of the Puna Plateau surface is covered by wind eroded or wind deposited landforms. These landforms align with the dominant wind direction (southeast) determined from ~450 ventifact measurements from 9 locations on the plateau. Twelve amalgamated samples sets that span six lithologies (granite, gneiss, quartzite, rhyolite, diabase, and basalt) using four cosmogenic isotopes (10Be, 26Al, 36Cl, 3He) on ventifacted clasts were collected from two surfaces to identify the most appropriate lithologies and cosmogenic isotopes for obtaining an accurate chronology of desert pavements. Moreover, 3He dating of six in situ samples from basalt flows with independent 39Ar/40Ar ages will begin to address long-term time-averaged wind erosion rates of bedrock while enabling wind-erosion rate corrections for pavement ventifacts. Our results and methodology can be applied worldwide and will aid future research in the many environments where ventifacts and/or high wind erosion rates are found.

Migration of Beryllium via Multiple Exposure Pathways among Work Processes in Four Different Facilities

PubMed Central

Armstrong, Jenna L.; Day, Gregory A.; Park, Ji Young; Stefaniak, Aleksandr B.; Stanton, Marcia L.; Deubner, David C.; Kent, Michael S.; Schuler, Christine R.; Virji, M. Abbas

2016-01-01

Inhalation of beryllium is associated with the development of sensitization; however, dermal exposure may also be important. The primary aim of this study was to elucidate relationships among exposure pathways in four different manufacturing and finishing facilities. Secondary aims were to identify jobs with increased levels of beryllium in air, on skin, and on surfaces; identify potential discrepancies in exposure pathways, and determine if these are related to jobs with previously identified risk. Beryllium was measured in air, on cotton gloves, and on work surfaces. Summary statistics were calculated and correlations among all three measurement types were examined at the facility and job level. Exposure ranking strategies were used to identify jobs with higher exposures. The highest air, glove, and surface measurements were observed in beryllium metal production and beryllium oxide ceramics manufacturing jobs that involved hot processes and handling powders. Two finishing and distribution facilities that handle solid alloy products had lower exposures than the primary production facilities, and there were differences observed among jobs. For all facilities combined, strong correlations were found between air-surface (rp ≥ 0.77), glove-surface (rp ≥ 0.76), and air-glove measurements (rp ≥ 0.69). In jobs where higher risk of beryllium sensitization or disease has been reported, exposure levels for all three measurement types were higher than in jobs with lower risk, though they were not the highest. Some jobs with low air concentrations had higher levels of beryllium on glove and surface wipe samples, suggesting a need to further evaluate the causes of the discrepant levels. Although such correlations provide insight on where beryllium is located throughout the workplace, they cannot identify the direction of the pathways between air, surface, or skin. Ranking strategies helped to identify jobs with the highest combined air, glove, and/or surface exposures. All previously identified high-risk jobs had high air concentrations, dermal mass loading, or both, and none had low dermal and air. We have found that both pathways are relevant. PMID:25357184

Effects of High-Temperature Exposures on the Fatigue Life of Superalloy Udimet(Registered Trademark) 720

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Telesman, Jack; Kantzos, Peter T.; Sweeney, Joseph W.; Browning, Paul F.

2002-01-01

The purpose of this study was to examine the effects of extended exposures on the near-surface fatigue resistance of a disk superalloy. Powder metallurgy processed, supersolvus heat-treated Udimet 720 (U720) fatigue specimens were exposed in air at temperatures from 650 to 705 C for 100 hr to over 1000 hr. They were then tested using conventional fatigue tests at 650 C to determine the effects of exposure on fatigue resistance. The exposures reduced life by up to 70% and increased the scatter in life, compared to unexposed levels. Fractographic evaluations indicated the failure mode was shifted by the exposures from internal to surface crack initiations. The increased scatter in life was related to the competition between internal crack initiations at inclusions or large grains producing longer lives, and surface crack initiations at an environmentally affected surface layer producing shorter lives.

Music videos, pro wrestling, and acceptance of date rape among middle school males and females: an exploratory analysis.

PubMed

Kaestle, Christine Elizabeth; Halpern, Carolyn Tucker; Brown, Jane D

2007-02-01

Exposure to televised music videos and pro wrestling were associated with rape acceptance (lower levels of agreeing with the statement "forcing a partner to have sex is never OK") among males, but not females, in a sample of 904 middle school students (controlling for overall television exposure, parenting style, and demographics).

Exposure to Family Violence as a Predictor of Dating Violence and Child-to-Parent Aggression in Spanish Adolescents

ERIC Educational Resources Information Center

Izaguirre, Ainhoa; Calvete, Esther

2017-01-01

Witnessing intimate partner violence (IPV) and child maltreatment may place children on a lifelong trajectory toward violence. The primary aim of this research was to examine the associations between exposure to violence at home and two forms of violence in close relationships in Spanish adolescents: child-to-parent violence (CPV) and dating…

Post-Traumatic Stress and Alcohol-Related Problems Following a College Shooting: Effect of Help-Seeking

ERIC Educational Resources Information Center

Siebert, Erin C.; Stewart, David G.; Hu, Emily M.; Estoup, Ashley C.; Underbrink, Erin G.; Moore, Lindsay S.

2018-01-01

Our aim was to test the hypothesized relationships between trauma exposure and alcohol-related problems, mediated by PTS symptoms, moderated by prior trauma exposure and help-seeking. Participants were 244 members of a private university who were enrolled or employed at the school on the date of a campus shooting. Online measures were distributed…

Mass, surface area and number metrics in diesel occupational exposure assessment.

PubMed

Ramachandran, Gurumurthy; Paulsen, Dwane; Watts, Winthrop; Kittelson, David

2005-07-01

While diesel aerosol exposure assessment has traditionally been based on the mass concentration metric, recent studies have suggested that particle number and surface area concentrations may be more health-relevant. In this study, we evaluated the exposures of three occupational groups-bus drivers, parking garage attendants, and bus mechanics-using the mass concentration of elemental carbon (EC) as well as surface area and number concentrations. These occupational groups are exposed to mixtures of diesel and gasoline exhaust on a regular basis in various ratios. The three groups had significantly different exposures to workshift TWA EC with the highest levels observed in the bus garage mechanics and the lowest levels in the parking ramp booth attendants. In terms of surface area, parking ramp attendants had significantly greater exposures than bus garage mechanics, who in turn had significantly greater exposures than bus drivers. In terms of number concentrations, the exposures of garage mechanics exceeded those of ramp booth attendants by a factor of 5-6. Depending on the exposure metric chosen, the three occupational groups had quite different exposure rankings. This illustrates the importance of the choice of exposure metric in epidemiological studies. If these three occupational groups were part of an epidemiological study, depending on the metric used, they may or may not be part of the same similarly exposed group (SEG). The exposure rankings (e.g., low, medium, or high) of the three groups also changes with the metric used. If the incorrect metric is used, significant misclassification errors may occur.

Long-Duration Orbit Exposure Experiment with Sub-Surface Microorganism from a Mars Terrestrial Analog

NASA Astrophysics Data System (ADS)

Davila, A. F.; Lim, D.; Fairen, A. G.; Uceda, E. R.; Zavaleta, J.; McKay, C.

2007-07-01

Orbit Exposure Experiments (OEE) allow us to test the possibility of life transfer between planets and moons. Deep sub-surface microorganisms may be the best candidates to survive long-term exposure to space conditions. A long duration OEE is proposed to test our hypothesis.

AGE (Argon Geochronology Experiment): An Instrument for Geochronology on the Surface of Mars

NASA Technical Reports Server (NTRS)

Swindle, T. D.; Bode, R.; Boynton, W. V.; Kring, D. A.; Williams, M.; Chutjian, A.; Darrach, M. R.; Cremers, D. A.; Wiens, R. C.; Baldwin, S. L.

2003-01-01

As our knowledge of the planet Mars continues to grow, one parameter that remains elusive is the absolute chronology of the planet s geological history. Although crater counts have provided a robust relative chronology, impactor fluxes are poorly enough known that there are places on Mars where the absolute age is uncertain by a factor of two or more. To resolve these uncertainties, it will be necessary to either analyze well-documented samples returned to the Earth from the Martian surface or to perform in situ measurements with sufficient precision. Sample return is still at least a decade away, and even then it might be from a biologically interesting area that might be geologically complex. Hence an in situ measurement, within an uncertainty of 20% or better, could greatly improve our knowledge of the history of Mars. With funding from the Planetary Instrument Definition and Development Program (PIDDP), we have been working on an instrument to perform potassium-argon (K-Ar) and cosmic-ray exposure (CRE) dating in situ on the surface of Mars. For either of these techniques, it is necessary to measure the abundance of one or more major or minor elements (K in the case of KAr; all majors and minors in the case of CRE) and the abundance and isotopes composition of a noble gas (Ar in the case of K-Ar; He, Ne and Ar for CRE dating). The technology for either of these types of measurements exists, but has never before been integrated for a spacecraft. We refer to the instrument as AGE, the Argon Geochronology Experiment (although we will measure the noble gases He and Ne as well for CRE ages). We report here on the basic components that go into such an instrument, both those that use existing technology and those that had to be developed to create the integrated package.

The Tropospheric Ozone Assessment Report (TOAR): A community-wide effort to quantify tropospheric ozone in a rapidly changing world

NASA Astrophysics Data System (ADS)

Cooper, O. R.; Schultz, M.; Paoletti, E.; Galbally, I. E.; Naja, M. K.; Tarasick, D. W.; Evans, M. J.; Thompson, A. M.

2017-12-01

Tropospheric ozone is a greenhouse gas and pollutant detrimental to human health and crop and ecosystem productivity. Since 1990 a large portion of the anthropogenic emissions that react in the atmosphere to produce ozone has shifted from North America and Europe to Asia. This rapid shift, coupled with limited ozone monitoring in developing nations, left scientists unable to answer the most basic questions: Which regions of the world have the greatest human and plant exposure to ozone pollution? Is ozone continuing to decline in nations with strong emissions controls? To what extent is ozone increasing in the developing world? How can the atmospheric sciences community facilitate access to the ozone metrics necessary for quantifying ozone's impact on human health and crop/ecosystem productivity? To answer these questions the International Global Atmospheric Chemistry Project (IGAC) initiated the Tropospheric Ozone Assessment Report (TOAR). With over 220 member scientists and air quality specialists from 36 nations, TOAR's mission is to provide the research community with an up-to-date scientific assessment of tropospheric ozone's global distribution and trends from the surface to the tropopause. TOAR has also built the world's largest database of surface ozone observations and generated ozone exposure and dose metrics at thousands of measurement sites around the world, freely accessible for research on the global-scale impact of ozone on climate, human health and crop/ecosystem productivity. Plots of these metrics show the regions of the world with the greatest ozone exposure for humans and crops/ecosystems, at least in areas where observations are available. The results also highlight regions where air quality is improving and where it has degraded. TOAR has also conducted the first intercomparison of tropospheric column ozone from ozonesondes and multiple satellite instruments, which provide similar estimates of the present-day tropospheric ozone burden.

The Diesel Exhaust in Miners Study: II. Exposure monitoring surveys and development of exposure groups.

PubMed

Coble, Joseph B; Stewart, Patricia A; Vermeulen, Roel; Yereb, Daniel; Stanevich, Rebecca; Blair, Aaron; Silverman, Debra T; Attfield, Michael

2010-10-01

Air monitoring surveys were conducted between 1998 and 2001 at seven non-metal mining facilities to assess exposure to respirable elemental carbon (REC), a component of diesel exhaust (DE), for an epidemiologic study of miners exposed to DE. Personal exposure measurements were taken on workers in a cross-section of jobs located underground and on the surface. Air samples taken to measure REC were also analyzed for respirable organic carbon (ROC). Concurrent measurements to assess exposure to nitric oxide (NO) and nitrogen dioxide (NO₂), two gaseous components of DE, were also taken. The REC measurements were used to develop quantitative estimates of average exposure levels by facility, department, and job title for the epidemiologic analysis. Each underground job was assigned to one of three sets of exposure groups from specific to general: (i) standardized job titles, (ii) groups of standardized job titles combined based on the percentage of time in the major underground areas, and (iii) larger groups based on similar area carbon monoxide (CO) air concentrations. Surface jobs were categorized based on their use of diesel equipment and proximity to DE. A total of 779 full-shift personal measurements were taken underground. The average REC exposure levels for underground jobs with five or more measurements ranged from 31 to 58 μg m⁻³ at the facility with the lowest average exposure levels and from 313 to 488 μg m⁻³ at the facility with the highest average exposure levels. The average REC exposure levels for surface workers ranged from 2 to 6 μg m⁻³ across the seven facilities. There was much less contrast in the ROC compared with REC exposure levels measured between surface and underground workers within each facility, as well as across the facilities. The average ROC levels underground ranged from 64 to 195 μg m⁻³, while on the surface, the average ROC levels ranged from 38 to 71 μg m⁻³ by facility, an ∼2- to 3-fold difference. The average NO and NO₂ levels underground ranged from 0.20 to 1.49 parts per million (ppm) and from 0.10 to 0.60 ppm, respectively, and were ∼10 times higher than levels on the surface, which ranged from 0.02 to 0.11 ppm and from 0.01 to 0.06 ppm, respectively. The ROC, NO, and NO₂ concentrations underground were correlated with the REC levels (r = 0.62, 0.71, and 0.62, respectively). A total of 80% of the underground jobs were assigned an exposure estimate based on measurements taken for the specific job title or for other jobs with a similar percentage of time spent in the major underground work areas. The average REC exposure levels by facility were from 15 to 64 times higher underground than on the surface. The large contrast in exposure levels measured underground versus on the surface, along with the differences between the mining facilities and between underground jobs within the facilities resulted in a wide distribution in the exposure estimates for evaluation of exposure-response relationships in the epidemiologic analyses.

Nano-scale topography of bearing surface in advanced alumina/zirconia hip joint before and after severe exposure in water vapor environment.

PubMed

Pezzotti, Giuseppe; Saito, Takuma; Padeletti, Giuseppina; Cossari, Pierluigi; Yamamoto, Kengo

2010-06-01

The aim of this study was to perform a surface morphology assessment with nanometer scale resolution on femoral heads made of an advanced zirconia toughened alumina (ZTA) composite. Femoral heads were characterized to a degree of statistical accuracy in the as-received state and after exposures up to 100 h in severe vapor-moist environment. Surface screening was made using an atomic force microscope (AFM). Scanning was systematically repeated on portions of surface as large as several tens of micrometers, randomly selected on the head surface, to achieve sufficient statistical reliability without lowering the nanometer-scale spatial resolution of the roughness measurement. No significant difference was found in the recorded values of surface roughness after environmental exposure (at 134 degrees C, under 2 bar), which was always comparable to that of the as-received head. Surface roughness safely lay <10 nm after environmental exposures up to 100 h, which corresponded to an exposure time in vivo of several human lifetimes (i.e., according to an experimentally derived thermal activation energy). In addition, the roughness results were significantly (about one order of magnitude) lower as compared to those recorded on femoral heads made of monolithic zirconia tested under the same conditions. (c) 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Weathering pits as indicators of the relative age of granite surfaces in the Cairngorm mountains, Scotland

USGS Publications Warehouse

Hall, A.M.; Phillips, W.M.

2006-01-01

Weathering pits 1-140 cm deep occur on granite surfaces in the Cairngorms associated with a range of landforms, including tors, glacially exposed slabs, large erratics and blockfields. Pit depth is positively correlated with cosmogenic exposure age, and both measures show consistent relationships on individual rock landforms. Rates of pit deepening are non-linear and a best fit is provided by the sigmoidal function D = b1+ exp(b2+b3/t). The deepest pits occur on unmodified tor summits, where 10 Be exposure ages indicate that surfaces have been exposed to weathering for a minimum of 52-297 ka. Glacially exposed surfaces with pits 10-46 cm deep have given 10 Be exposure durations of 21-79 ka, indicating exposure by glacial erosion before the last glacial cycle. The combination of cosmogenic exposure ages with weathering pit depths greatly extends the area over which inferences can be made regarding the ages of granite surfaces in the Cairngorms. Well-developed weathering pits on glacially exposed surfaces in other granite areas are potential indicators of glacial erosion before the Last Glacial Maximum. ?? Swedish Society for Anthropology and Geography.

Neonate exposure to thimerosal mercury from hepatitis B vaccines.

PubMed

Dórea, José G; Marques, Rejane C; Brandão, Katiane G

2009-08-01

Infant exposure to ethylmercury (EtHg) has not only increased but is starting earlier as a result of the current immunization schedule that uses thimerosal-containing vaccines (TCVs). Although vaccination schedule varies considerably between countries, infants in less-developed countries continue to be exposed to EtHg derived from more affordable TCVs. We studied the exposure of newborns to EtHg from hepatitis B vaccines; hospital records (21,685) were summarized for the years 2001 to 2005 regarding date of birth, vaccination date, and birth weight. Most of the vaccinations occurred in the first 24 hours postdelivery; over the 5 years, there was an increase in vaccinations within hours of birth (same day), from 7.4% (2001) to 87.8% (2005). Nearly 94.6% of infants are now being vaccinated within the first 24 hours. Range of mercury exposure spread from 4.2 to 21.1 microg mercury/kg body weight for those receiving TCVs with the highest thimerosal concentration; these exposure levels are conservative for 2% of children receiving vaccines within 2 to 3 postnatal days, when they are still going through physiological postnatal weight loss. Because of the particular timing (transitioning from in utero to ex utero metabolism) and specific aspects of exposure (i.e., parenteral mode, bypassing gastroenteric barriers) and dose (related to vaccine manufacturer and with variation in birth weight), this study reveals critical issues that can modulate toxicokinetics and toxicodynamics of organomercurials in neonates.

Southern westerly winds: a pacemaker of Holocene glacial fluctuations in Patagonia?

NASA Astrophysics Data System (ADS)

Sagredo, E. A.; Reynhout, S.; Kaplan, M. R.; Patricio, M. I.; Aravena, J. C.; Martini, M. A.; Schaefer, J. M.

2017-12-01

A well-resolved glacial chronology is crucial to compare sequences of glacial/climate events within and between regions, and thus, to unravel mechanisms underlying past climate changes. Important efforts have been made towards understanding the Holocene climate evolution of the Southern Andes; however, the timing, patterns and causes of glacial fluctuations during this period still remain elusive. Recent advances in terrestrial cosmogenic nuclide surface exposure dating, together with the establishment of a Patagonian 10Be production rate, have opened new possibilities for establishing high-resolution glacial chronologies at centennial/decadal scale. Here we present a 10Be surface exposure chronology of fluctuations of a small, climate-sensitive mountain glacier at Mt. Fitz Roy area (49.3°S), spanning from the last glacial termination to the present. Thirty new 10Be ages show glacial advances and moraine building events at 17.1±0.9 ka, 13.5±0.5 ka, 10.2±0.7 ka or 9.9±0.5 ka, 6.9±0.2 ka, 6.1±0.3 ka, 4.5±0.2 ka and 0.5±0.1 ka. Similar to the pattern observed in New Zealand, this sequence features progressively less extensive glacial advances during the late-glacial and early Holocene, followed by advances of roughly similar extent during the mid- to late-Holocene. We suggest that while the magnitude of Holocene glacial fluctuations in Patagonia is modulated by SH summer insolation ("modulator"), the specific timing of these glacial events is influenced by centennial-scale shifts of the Southern Westerly Winds ("pacemaker").

Lunar Dust: Properties and Investigation Techniques

NASA Astrophysics Data System (ADS)

Kuznetsov, I. A.; Zakharov, A. V.; Dolnikov, G. G.; Lyash, A. N.; Afonin, V. V.; Popel, S. I.; Shashkova, I. A.; Borisov, N. D.

2017-12-01

Physical conditions in the near-surface layer of the Moon are overviewed. This medium is formed in the course of the permanent micrometeoroid bombardment of the lunar regolith and due to the exposure of the regolith to solar radiation and high-energy charged particles of solar and galactic origin. During a considerable part of a lunar day (more than 20%), the Moon is passing through the Earth's magnetosphere, where the conditions strongly differ from those in the interplanetary space. The external effects on the lunar regolith form the plasma-dusty medium above the lunar surface, the so-called lunar exosphere, whose characteristic altitude may reach several tens of kilometers. Observations of the near-surface dusty exosphere were carried out with the TV cameras onboard the landers Surveyor 5, 6, and 7 (1967-1968) and with the astrophotometer of Lunokhod-2 (1973). Their results showed that the near-surface layer glows above the sunlit surface of the Moon. This was interpreted as the scattering of solar light by dust particles. Direct detection of particles on the lunar surface was made by the Lunar Ejects and Meteorite (LEAM) instrument deployed by the Apollo 17 astronauts. Recently, the investigations of dust particles were performed by the Lunar Atmosphere and Dust Environment Explorer (LADEE) instrument at an altitude of several tens of kilometers. These observations urged forward the development of theoretical models for the lunar exosphere formation, and these models are being continuously improved. However, to date, many issues related to the dynamics of dust and the near-surface electric fields remain unresolved. Further investigations of the lunar exosphere are planned to be performed onboard the Russian landers Luna-Glob and Luna-Resurs.

An experiment on the dynamics of ion implantation and sputtering of surfaces

NASA Astrophysics Data System (ADS)

Wright, G. M.; Barnard, H. A.; Kesler, L. A.; Peterson, E. E.; Stahle, P. W.; Sullivan, R. M.; Whyte, D. G.; Woller, K. B.

2014-02-01

A major impediment towards a better understanding of the complex plasma-surface interaction is the limited diagnostic access to the material surface while it is undergoing plasma exposure. The Dynamics of ION Implantation and Sputtering Of Surfaces (DIONISOS) experiment overcomes this limitation by uniquely combining powerful, non-perturbing ion beam analysis techniques with a steady-state helicon plasma exposure chamber, allowing for real-time, depth-resolved in situ measurements of material compositions during plasma exposure. Design solutions are described that provide compatibility between the ion beam analysis requirements in the presence of a high-intensity helicon plasma. The three primary ion beam analysis techniques, Rutherford backscattering spectroscopy, elastic recoil detection, and nuclear reaction analysis, are successfully implemented on targets during plasma exposure in DIONISOS. These techniques measure parameters of interest for plasma-material interactions such as erosion/deposition rates of materials and the concentration of plasma fuel species in the material surface.

An experiment on the dynamics of ion implantation and sputtering of surfaces.

PubMed

Wright, G M; Barnard, H A; Kesler, L A; Peterson, E E; Stahle, P W; Sullivan, R M; Whyte, D G; Woller, K B

2014-02-01

A major impediment towards a better understanding of the complex plasma-surface interaction is the limited diagnostic access to the material surface while it is undergoing plasma exposure. The Dynamics of ION Implantation and Sputtering Of Surfaces (DIONISOS) experiment overcomes this limitation by uniquely combining powerful, non-perturbing ion beam analysis techniques with a steady-state helicon plasma exposure chamber, allowing for real-time, depth-resolved in situ measurements of material compositions during plasma exposure. Design solutions are described that provide compatibility between the ion beam analysis requirements in the presence of a high-intensity helicon plasma. The three primary ion beam analysis techniques, Rutherford backscattering spectroscopy, elastic recoil detection, and nuclear reaction analysis, are successfully implemented on targets during plasma exposure in DIONISOS. These techniques measure parameters of interest for plasma-material interactions such as erosion/deposition rates of materials and the concentration of plasma fuel species in the material surface.

Green mosses date the Storegga tsunami to the chilliest decades of the 8.2 ka cold event

NASA Astrophysics Data System (ADS)

Bondevik, Stein; Stormo, Svein Kristian; Skjerdal, Gudrun

2012-06-01

Chlorophyll in dead plants ordinarily decomposes completely before permanent burial through exposure to light, water and oxygen. Here we describe 8000-year-old terrestrial mosses that retain several percent of its original chlorophyll. The mosses were ripped of the land surface, carried 50-100 m off the Norwegian coast of the time, and deposited in depressions on the sea floor by the Storegga tsunami. A little of the chlorophyll survived because, within hours after entraining it, the tsunami buried the mosses in shell-rich sediments. These sediments preserved the chlorophyll by keeping out light and oxygen, and by keeping the pH above 7—three factors known to favour chlorophyll's stability. Because the green mosses were buried alive, their radiocarbon clock started ticking within hours after the Storegga Slide had set off the tsunami. Radiocarbon measurement of the mosses therefore give slide ages of uncommon geological precision, and these, together with a sequence of ages above and below the boundary, date the Storegga Slide to the chilliest decades of the 8.2 ka cold event at 8120-8175 years before AD 1950. North Atlantic coastal- and fjord- climatic records claimed to show evidence of the 8.2 cold event should be carefully examined for possible contamination and disturbance from the Storegga tsunami.

Purdue Rare Isotope Measurement Laboratory

NASA Astrophysics Data System (ADS)

Caffee, M.; Elmore, D.; Granger, D.; Muzikar, P.

2002-12-01

The Purdue Rare Isotope Measurement Laboratory (PRIME Lab) is a dedicated research and service facility for accelerator mass spectrometry. AMS is an ultra-sensitive analytical technique used to measure low levels of long-lived cosmic-ray-produced and anthropogenic radionuclides, and rare trace elements. We measure 10Be (T1/2 = 1.5 My), 26Al (.702 My), 36Cl (.301 My), and 129I (16 My), in geologic samples. Applications include dating the cosmic-ray-exposure time of rocks on Earth's surface, determining rock and sediment burial ages, measuring the erosion rates of rocks and soils, and tracing and dating ground water. We perform sample preparation and separation chemistries for these radio-nuclides for our internal research activities and for those external researchers not possessing this capability. Our chemical preparation laboratories also serve as training sites for members of the geoscience community developing these techniques at their institutions. Research at Purdue involves collaborators among members of the Purdue Departments of Physics, Earth and Atmospheric Sciences, Chemistry, Agronomy, and Anthropology. We also collaborate and serve numerous scientists from other institutions. We are currently in the process of modernizing the facility with the goals of higher precision for routinely measured radio-nuclides, increased sample throughput, and the development of new measurement capabilities for the geoscience community.

Improving Joint Function Using Photochemical Hydrogels for Articular Surface Repair

DTIC Science & Technology

2014-10-01

some researchers have used microparticles for controlled release presentation of growth factors to encapsulated chondrocytes.13 While this approach ... control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE October 2014 2. REPORT TYPE Annual 3. DATES COVERED 30 Sep 2013...surface repair. The scope of this research is to develop regenerative medicine approaches involving biocompatible hydrogel scaffolds seeded with

Age, distribution, and significance within a sediment budget, of in-channel depositional surfaces in the Normanby River, Queensland, Australia

NASA Astrophysics Data System (ADS)

Pietsch, T. J.; Brooks, A. P.; Spencer, J.; Olley, J. M.; Borombovits, D.

2015-06-01

We present the results of investigations into alluvial deposition in the catchment of the Normanby River, which flows into Princess Charlotte Bay (PCB) in the northern part of the Great Barrier Reef Lagoon. Our focus is on the fine fraction (< ~ 63 μm) of alluvial deposits that sit above the sand and gravel bars of the channel floor, but below the expansive flat surface generally referred to as the floodplain. Variously described as benches, bank attached bars or inset or inner floodplains, these more or less flat-lying surfaces within the macro-channel have hitherto received little attention in sediment budgeting models. We use high resolution LiDAR based mapping combined with optical dating of exposures cut into these in-channel deposits to compare their aggradation rates with those found in other depositional zones in the catchment, namely the floodplain and coastal plain. In total 59 single grain OSL dates were produced across 21 stratigraphic profiles at 14 sites distributed though the 24 226 km2 catchment. In-channel storage in these inset features is a significant component of the contemporary fine sediment budget (i.e. recent decades/last century), annually equivalent to more than 50% of the volume entering the channel network from hillslopes and subsoil sources. Therefore, at the very least, in-channel storage of fine material needs to be incorporated into sediment budgeting exercises. Furthermore, deposition within the channel has occurred in multiple locations coincident in time with accelerated sediment production following European settlement. Generally, this has occurred on a subset of the features we have examined here, namely linear bench features low in the channel. This suggests that accelerated aggradation on in-channel depositional surfaces has been in part a response to accelerated erosion within the catchment. The entire contribution of ~ 370 kilotonnes per annum of fine sediment estimated to have been produced by alluvial gully erosion over the last ~ 100 years can be accounted for by that stored as in-channel alluvium. These features therefore can play an important role in mitigating the impact on the receiving water of accelerated erosion.

Biostratigraphy and chronostratigraphy of the area between Sarasota and Lake Okeechobee, southern Florida: An integrated approach

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

Wingard, G.L.; Edwards, L.E.; McCartan, L.

1993-03-01

Preliminary analysis of paleontologic and isotopic data from 15 coreholes, integrated with the lithostratigraphic framework, has revealed three chronostratigraphic depositional units in the subsurface of the Arcadia and Sarasota 30 [times] 60-minute quadrangles, in the southern Florida peninsula. (1) An upper Oligocene depositional unit unconformably overlies the lower Oligocene Suwannee Formation and has been dated by using [sup 87]Sr/[sup 86]Sr values and molluscs. (2) A lower and middle Miocene depositional unit has been dated on the basis of [sup 87]Sr/[sup 86]Sr values, molluscs, and dinoflagellates. The upper boundary of this unit is marked by the top of the Venice Claymore » in the western part of the study area. (3) A Pliocene and Pleistocene depositional unit, dated on the basis of [sup 87]Sr/[sup 86]Sr values, molluscs, dinoflagellates, foraminifera, ostracodes, and pollen, unconformably overlies the lower and middle Miocene beds; this unconformity represents approximately a 13-million-year gap in the record. The Pliocene and Pleistocene unit is seen in the surficial deposits of the Caloosahatchee, Tamiami, Bermont, and Fort Thompson Formations. The interpretation of Florida's geologic history is hampered by the interfingering of onlap/offlap cycles from two coastlines, a unique situation in southeastern coastal plain geology. In addition, a complex diagenetic history, mixing of carbonate and siliciclastic regimes, and lack of surface exposures make interpretation of the stratigraphic sequences difficult. The chronostratigraphic depositional units identified cut across lithofacies boundaries and allow correlation across the Florida peninsula, thus leading to the development of coherent, well-defined lithostratigraphic units.« less

Late Pleistocene glaciation of the Mt Giluwe volcano, Papua New Guinea

USGS Publications Warehouse

Barrows, T.T.; Hope, G.S.; Prentice, M.L.; Fifield, L.K.; Tims, S.G.

2011-01-01

The Mt Giluwe shield volcano was the largest area glaciated in Papua New Guinea during the Pleistocene. Despite minimal cooling of the sea surface during the last glacial maximum, glaciers reached elevations as low as 3200 m. To investigate changes in the extent of ice through time we have re-mapped evidence for glaciation on the southwest flank of Mt Giluwe. We find that an ice cap has formed on the flanks of the mountain on at least three, and probably four, separate occasions. To constrain the ages of these glaciations we present 39 new cosmogenic 36Cl exposure ages complemented by new radiocarbon dates. Direct dating of the moraines identifies that the maximum extent of glaciation on the mountain was not during the last glacial maximum as previously thought. In conjunction with existing potassium/argon and radiocarbon dating, we recognise four distinct glacial periods between 293-306 ka (Gogon Glaciation), 136-158 ka (Mengane Glaciation), centred at 62 ka (Komia Glaciation) and from >20.3-11.5 ka (Tongo Glaciation). The temperature difference relative to the present during the Tongo Glaciation is likely to be of the order of at least 5 ??C which is a minimum difference for the previous glaciations. During the Tongo Glaciation, ice was briefly at its maximum for less than 1000 years, but stayed near maximum levels for nearly 4000 years, until about 15.4 ka. Over the next 4000 years there was more rapid retreat with ice free conditions by the early Holocene. ?? 2011 Elsevier Ltd.

Dated Plant Phylogenies Resolve Neogene Climate and Landscape Evolution in the Cape Floristic Region

PubMed Central

2015-01-01

In the context of molecularly-dated phylogenies, inferences informed by ancestral habitat reconstruction can yield valuable insights into the origins of biomes, palaeoenvironments and landforms. In this paper, we use dated phylogenies of 12 plant clades from the Cape Floristic Region (CFR) in southern Africa to test hypotheses of Neogene climatic and geomorphic evolution. Our combined dataset for the CFR strengthens and refines previous palaeoenvironmental reconstructions based on a sparse, mostly offshore fossil record. Our reconstructions show remarkable consistency across all 12 clades with regard to both the types of environments identified as ancestral, and the timing of shifts to alternative conditions. They reveal that Early Miocene land surfaces of the CFR were wetter than at present and were dominated by quartzitic substrata. These conditions continue to characterize the higher-elevation settings of the Cape Fold Belt, where they have fostered the persistence of ancient fynbos lineages. The Middle Miocene (13–17 Ma) saw the development of perennial to weakly-seasonal arid conditions, with the strongly seasonal rainfall regime of the west coast arising ~6.5–8 Ma. Although the Late Miocene may have seen some exposure of the underlying shale substrata, the present-day substrate diversity of the CFR lowlands was shaped by Pliocene-Pleistocene events. Particularly important was renewed erosion, following the post-African II uplift episode, and the reworking of sediments on the coastal platform as a consequence of marine transgressions and tectonic uplift. These changes facilitated adaptive radiations in some, but not all, lineages studied. PMID:26422465

Age of Barrier Canyon-style rock art constrained by cross-cutting relations and luminescence dating techniques.

PubMed

Pederson, Joel L; Chapot, Melissa S; Simms, Steven R; Sohbati, Reza; Rittenour, Tammy M; Murray, Andrew S; Cox, Gary

2014-09-09

Rock art compels interest from both researchers and a broader public, inspiring many hypotheses about its cultural origin and meaning, but it is notoriously difficult to date numerically. Barrier Canyon-style (BCS) pictographs of the Colorado Plateau are among the most debated examples; hypotheses about its age span the entire Holocene epoch and previous attempts at direct radiocarbon dating have failed. We provide multiple age constraints through the use of cross-cutting relations and new and broadly applicable approaches in optically stimulated luminescence dating at the Great Gallery panel, the type section of BCS art in Canyonlands National Park, southeastern Utah. Alluvial chronostratigraphy constrains the burial and exhumation of the alcove containing the panel, and limits are also set by our related research dating both a rockfall that removed some figures and the rock's exposure duration before that time. Results provide a maximum possible age, a minimum age, and an exposure time window for the creation of the Great Gallery panel, respectively. The only prior hypothesis not disproven is a late Archaic origin for BCS rock art, although our age result of A.D. ∼ 1-1100 coincides better with the transition to and rise of the subsequent Fremont culture. This chronology is for the type locality only, and variability in the age of other sites is likely. Nevertheless, results suggest that BCS rock art represents an artistic tradition that spanned cultures and the transition from foraging to farming in the region.

Age of Barrier Canyon-style rock art constrained by cross-cutting relations and luminescence dating techniques

PubMed Central

Pederson, Joel L.; Chapot, Melissa S.; Simms, Steven R.; Sohbati, Reza; Rittenour, Tammy M.; Murray, Andrew S.; Cox, Gary

2014-01-01

Rock art compels interest from both researchers and a broader public, inspiring many hypotheses about its cultural origin and meaning, but it is notoriously difficult to date numerically. Barrier Canyon-style (BCS) pictographs of the Colorado Plateau are among the most debated examples; hypotheses about its age span the entire Holocene epoch and previous attempts at direct radiocarbon dating have failed. We provide multiple age constraints through the use of cross-cutting relations and new and broadly applicable approaches in optically stimulated luminescence dating at the Great Gallery panel, the type section of BCS art in Canyonlands National Park, southeastern Utah. Alluvial chronostratigraphy constrains the burial and exhumation of the alcove containing the panel, and limits are also set by our related research dating both a rockfall that removed some figures and the rock’s exposure duration before that time. Results provide a maximum possible age, a minimum age, and an exposure time window for the creation of the Great Gallery panel, respectively. The only prior hypothesis not disproven is a late Archaic origin for BCS rock art, although our age result of A.D. ∼1–1100 coincides better with the transition to and rise of the subsequent Fremont culture. This chronology is for the type locality only, and variability in the age of other sites is likely. Nevertheless, results suggest that BCS rock art represents an artistic tradition that spanned cultures and the transition from foraging to farming in the region. PMID:25157162

A Protection Motivation Theory application to date rape education.

PubMed

Singh, Shweta; Orwat, John; Grossman, Susan

2011-12-01

Date rape risk communication is a key component of education-based Date Rape Prevention Programs, common across colleges. In such programs, risk assessment in date rape is approached cautiously in order to avoid a tone of "victim blaming." Since it is important in the assessment of any risk to understand the surrounding social context of the risky situation and the individual's unique relationship with that social context, this study examines Protection Motivation Theory as it applies to handling the risk of date rape without victim blaming. The paper links individual personality and social contexts with risk communication. The study sample comprised 367 undergraduate women enrolled in a large Southern Public University. The study examines the relationships between dating activity, social competency, and type of information provided with the dependents variables of date rape related protection behavior (intent), belief, and knowledge. A factorial multiple analysis of covariance analysis found that the dependent variables had a significant relationship with aspects of social competency and dating activity. The exposure to varying information about date rape was not significantly related to the dependent variables of date rape-related protection behavior (intent), belief, and knowledge. The identification of social competency and dating activity status as protective factors in this study makes a significant contribution to the practice and research efforts in date rape education.

The Diesel Exhaust in Miners Study: II. Exposure Monitoring Surveys and Development of Exposure Groups

PubMed Central

Coble, Joseph B.; Stewart, Patricia A.; Vermeulen, Roel; Yereb, Daniel; Stanevich, Rebecca; Blair, Aaron; Silverman, Debra T.; Attfield, Michael

2010-01-01

Air monitoring surveys were conducted between 1998 and 2001 at seven non-metal mining facilities to assess exposure to respirable elemental carbon (REC), a component of diesel exhaust (DE), for an epidemiologic study of miners exposed to DE. Personal exposure measurements were taken on workers in a cross-section of jobs located underground and on the surface. Air samples taken to measure REC were also analyzed for respirable organic carbon (ROC). Concurrent measurements to assess exposure to nitric oxide (NO) and nitrogen dioxide (NO2), two gaseous components of DE, were also taken. The REC measurements were used to develop quantitative estimates of average exposure levels by facility, department, and job title for the epidemiologic analysis. Each underground job was assigned to one of three sets of exposure groups from specific to general: (i) standardized job titles, (ii) groups of standardized job titles combined based on the percentage of time in the major underground areas, and (iii) larger groups based on similar area carbon monoxide (CO) air concentrations. Surface jobs were categorized based on their use of diesel equipment and proximity to DE. A total of 779 full-shift personal measurements were taken underground. The average REC exposure levels for underground jobs with five or more measurements ranged from 31 to 58 μg m−3 at the facility with the lowest average exposure levels and from 313 to 488 μg m−3 at the facility with the highest average exposure levels. The average REC exposure levels for surface workers ranged from 2 to 6 μg m−3 across the seven facilities. There was much less contrast in the ROC compared with REC exposure levels measured between surface and underground workers within each facility, as well as across the facilities. The average ROC levels underground ranged from 64 to 195 μg m−3, while on the surface, the average ROC levels ranged from 38 to 71 μg m−3 by facility, an ∼2- to 3-fold difference. The average NO and NO2 levels underground ranged from 0.20 to 1.49 parts per million (ppm) and from 0.10 to 0.60 ppm, respectively, and were ∼10 times higher than levels on the surface, which ranged from 0.02 to 0.11 ppm and from 0.01 to 0.06 ppm, respectively. The ROC, NO, and NO2 concentrations underground were correlated with the REC levels (r = 0.62, 0.71, and 0.62, respectively). A total of 80% of the underground jobs were assigned an exposure estimate based on measurements taken for the specific job title or for other jobs with a similar percentage of time spent in the major underground work areas. The average REC exposure levels by facility were from 15 to 64 times higher underground than on the surface. The large contrast in exposure levels measured underground versus on the surface, along with the differences between the mining facilities and between underground jobs within the facilities resulted in a wide distribution in the exposure estimates for evaluation of exposure–response relationships in the epidemiologic analyses. PMID:20876232

Solar Ion Processing of Itokawa Grains: Reconciling Model Predictions with Sample Observations

NASA Technical Reports Server (NTRS)

Christoffersen, Roy; Keller, L. P.

2014-01-01

Analytical TEM observations of Itokawa grains reported to date show complex solar wind ion processing effects in the outer 30-100 nm of pyroxene and olivine grains. The effects include loss of long-range structural order, formation of isolated interval cavities or "bubbles", and other nanoscale compositional/microstructural variations. None of the effects so far described have, however, included complete ion-induced amorphization. To link the array of observed relationships to grain surface exposure times, we have adapted our previous numerical model for progressive solar ion processing effects in lunar regolith grains to the Itokawa samples. The model uses SRIM ion collision damage and implantation calculations within a framework of a constant-deposited-energy model for amorphization. Inputs include experimentally-measured amorphization fluences, a Pi steradian variable ion incidence geometry required for a rotating asteroid, and a numerical flux-versus-velocity solar wind spectrum.

Using zircon (U-Th)/He damage-diffusivity patterns to quantify detachment-related basement exhumation in the Mecca Hills, CA

NASA Astrophysics Data System (ADS)

Moser, A. C.; Ault, A. K.; Evans, J. P.; Reiners, P. W.; Stearns, M.; Guenthner, W.

2017-12-01

Exposures of gneiss and Orocopia Schist (OS) in the Mecca Hills, California, adjacent to the southernmost San Andreas Fault system, preserve the exhumation history of Oligocene detachment faulting. We investigate the duration, magnitude, and mechanisms of exhumation of these units at regional and local scales using in situ U-Pb zircon dating (n = 248), (U-Th)/He (He) thermochronometry (n = 39), and He date-effective U (eU) patterns. Zircons with variable preserved visual metamictization were targeted for He analyses to purposefully build a dataset with a range in eU concentration and zircon He closure temperatures, as well as induce a He date-eU correlation. Analyzed zircon crystals range from clear and transparent to purple-brown and translucent in each sample. Zircon cathodoluminescence images reveal oscillatory and sector chemical zoning. Each sample contains a population of largely Proterozoic U-Pb dates implying some grains accumulated radiation damage since 1.9-1.1 Ga. Zircon (U-Th)/He dates from seven samples of OS and gneiss yield a mean date of 24 ± 3.5 Ma (n = 32) and uniform dates over an 90-2950 ppm eU range. One gneiss sample yields a mean date of 65 ± 5.6 Ma (n = 7) over a limited eU spread ( 500-950 ppm). Mean zircon He dates from these two units overlap, but dates are broadly younger in northeastern exposures dominated by OS. Preliminary thermal history simulations integrating zircon U-Pb data, He date-eU patterns, and independent geologic constraints require at least 200 °C of cooling through the zircon He partial retention zone 30-21 Ma and show that the pre-70 Ma thermal history does not affect the predicted date-eU correlation. This shared rapid cooling history documented in the OS and gneiss imply these units were juxtaposed prior to 30 Ma and exhumed as a coherent structural block within the footwall of the Orocopia Mountains Detachment Fault in the Mecca Hills. Spatio-temporal variation in mean zircon He dates may delineate time-transgressive cooling of these units as they exhumed. Zircon textures and overall invariant He dates regardless of eU imply that visual metamictization persists in zircons at temperatures >200 °C and indicates these grains experienced a thermal history characterized by temperatures that preserved visual damage but fully induced He loss in the crystals prior to exhumation.

Surface cleaning for enhanced adhesion to packaging surfaces: Effect of oxygen and ammonia plasma

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

Gaddam, Sneha; Dong, Bin; Driver, Marcus

2015-03-15

The effects of direct plasma chemistries on carbon removal from silicon nitride (SiN{sub x}) and oxynitride (SiO{sub x}N{sub y}) surfaces have been studied by in-situ x-ray photoelectron spectroscopy (XPS) and ex-situ contact angle measurements. The data indicate that O{sub 2} and NH{sub 3} capacitively coupled plasmas are effective at removing adventitious carbon from silicon nitride (SiN{sub x}) and Si oxynitride (SiO{sub x}N{sub y}) surfaces. O{sub 2} plasma treatment results in the formation of a silica overlayer. In contrast, the exposure to NH{sub 3} plasma results in negligible additional oxidation of the SiN{sub x} or SiO{sub x}N{sub y} surface. Ex-situ contactmore » angle measurements show that SiN{sub x} and SiO{sub x}N{sub y} surfaces exposed to oxygen plasma are initially more hydrophilic than surfaces exposed to NH{sub 3} plasma, indicating that the O{sub 2} plasma-induced SiO{sub 2} overlayer is highly reactive toward ambient. At longer ambient exposures (≳10 h), however, surfaces treated by either O{sub 2} or NH{sub 3} plasma exhibit similar steady state contact angles, correlated with rapid uptake of adventitious carbon, as determined by XPS. Surface passivation by exposure to molecular hydrogen prior to ambient exposure significantly retards the increase in contact angle upon exposure to ambient. The results suggest a practical route to enhancing the time available for effective bonding to surfaces in microelectronics packaging applications.« less

Oxygen plasma ashing effects on aluminum and titanium space protective coatings

NASA Technical Reports Server (NTRS)

Synowicki, R.; Kubik, R. D.; Hale, J. S.; Peterkin, Jane; Nafis, S.; Woollam, John A.; Zaat, S.

1991-01-01

Using variable angle spectroscopic ellipsometry and atomic force microscopy (AFM), the surface roughness and oxidation of aluminum and titanium thin films have been studied as a function of substrate deposition temperature and oxygen plasma exposure. Increasing substrate deposition temperatures affect film microstructure by greatly increasing grain size. Short exposures to an oxygen plasma environment produce sharp spikes rising rapidly above the surface as seen by AFM. Ellipsometric measurements were made over a wide range of plasma exposure times, and results at longer exposure times suggest that the surface is greater than 30% void. This is qualitatively verified by the AFM images.

Changes in Extracellular Striatal Acetylcholine and Brain Seizure Activity Following Acute Exposure to Nerve Against in Freely Moving Guinea Pigs

DTIC Science & Technology

2010-01-01

Literature 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Changes in extracellular striatal acetylcholine and brain seizure activity following...Acetylcholine, acetylcholinesterase, choline, guinea pig, in vivo microdialysis, nerve agents, organophosphorus compounds, sarin, seizure activity ...RESEARCH ARTICLE Changes in extracellular striatal acetylcholine and brain seizure activity following acute exposure to nerve agents in freely

Subliminal mere exposure and explicit and implicit positive affective responses.

PubMed

Hicks, Joshua A; King, Laura A

2011-06-01

Research suggests that repeated subliminal exposure to environmental stimuli enhances positive affective responses. To date, this research has primarily concentrated on the effects of repeated exposure on explicit measures of positive affect (PA). However, recent research suggests that repeated subliminal presentations may increase implicit PA as well. The present study tested this hypothesis. Participants were either subliminally primed with repeated presentations of the same stimuli or only exposed to each stimulus one time. Results confirmed predictions showing that repeated exposure to the same stimuli increased both explicit and implicit PA. Implications for the role of explicit and implicit PA in attitudinal judgements are discussed.

Proton pump inhibitors increase the incidence of bone fractures in hepatitis C patients.

PubMed

Mello, Michael; Weideman, Rick A; Little, Bertis B; Weideman, Mark W; Cryer, Byron; Brown, Geri R

2012-09-01

While proton pump inhibitors (PPI) may increase the risk of bone fractures, the incidence of new bone fractures in a chronic hepatitis C virus (HCV) infected cohort, with or without PPI exposure, has not been explored. A retrospective cohort study of the incidence of bone fractures over 10 years in 9,437 HCV antibody positive patients in the Dallas VA Hepatitis C Registry was performed. The study endpoint was the incidence of verified new bone fractures per patient-years (pt-yrs) in PPI users compared to non-PPI users. PPI use was defined as those taking a PPI for ≥360 days. Pt-yrs of exposure for PPI users began on the first PPI prescription date, and pt-yrs of exposure for non-PPI users began with first date of any non-PPI prescription. For both HCV groups, the final date of patients' study duration was defined by end of PPI exposure, bone fracture occurrence, death or end of study evaluation period. Exclusion criteria included use of bone health modifying medications ≥30 days. Statistical differences in fracture incidence between groups were determined by multivariate regression analysis. Among the total study population analyzed (n = 2,573), 109 bone fractures occurred. Unadjusted bone fracture incidences were 13.99/1,000 pt-yrs vs. 5.86/1,000 pt-yrs in PPI and non-PPI users, respectively. The adjusted hazard ratio for new bone fractures was 3.87 (95 % CI 2.46-6.08) (p < 0.001) in PPI users. In patients with chronic HCV, use of PPI for >1 year increased the risk of new bone fractures by more than threefold.

Applications of Cosmogenic He-3 and Ne-21 Dating to Glacial Moraines in Antarctica and California

NASA Astrophysics Data System (ADS)

Sams, S.; Morgan, D. J.; Balco, G.; Putkonen, J.; Bibby, T.

2015-12-01

The depositional age of moraines can be determined through cosmogenic nuclide exposure dating. These ages are useful in establishing a glacial history of an area and ascribing age constraints to transport processes. Be-10 is the most common nuclide used for exposure dating today, but this method is both expensive and time consuming because it requires analysis by accelerator mass spectrometry (AMS). He-3 and Ne-21 can be analyzed using noble gas mass spectrometry, which is more cost efficient than AMS and requires less chemical preparation. We collected samples from areas in Moraine Canyon, Antarctica (86.10° S, 157.75° W), which is a dry valley in the Transantarctic Mountains. Dolerite boulders along a transect of recessional moraines were sampled in the typical fashion of using a large piece of the boulder for analysis. Pyroxene minerals have been separated from these samples following the method of Bromley et al. (2014) using hydrofluoric acid. Exposure ages will be calculated from the He-3 concentrations in them. In the Mono Lake area of California, moraines were sampled from Bloody Canyon and McGee Creek sites. Instead of collecting a sample from an individual boulder, we collected approximately 25 granitic pebbles (1-3 cm) from 4-6 sites along the crest of the moraines following the method of Briner (2009). Each suite of pebbles was crushed together, and quartz minerals were separated from the agglomeration of pebbles. Cosmogenic Ne-21 will be measured from these samples to determine their exposure age. From these two field sites, we will use He-3 and Ne-21 to better understand the timing and extent of glaciation in these areas.

Concepts of skin protection: considerations for the evaluation and terminology of the performance of skin protective equipment.

PubMed

Brouwer, Derk H; Aitken, Robert J; Oppl, Reinhard; Cherrie, John W

2005-09-01

This article proposes a common language for better understanding processes involved in dermal exposure and skin protection. A conceptual model has been developed that systematically describes the transport of agent mass from sources, eventually resulting in "loading" of the skin surface or the skin contaminant layer. In view of a harmonized glossary of exposure terminology this is considered the exposure surface. Loading is defined as agent mass present in this layer divided by the exposure surface area. Skin protective equipment (SPE) is meant to reduce uptake, that is, an agent crosses the absorption barrier of the skin, by intervening in the processes of loading the exposure surface; however, the design of the equipment may fail to cover skin surface entirely. In addition, part of the mass intercepted by the SPE may reach the skin surface either by permeation, penetration, or by transfer when touching the contaminated exterior of the SPE. Evaluation of SPE performance has earlier focused on chemical resistance performance testing for permeation, penetration, or degradation of SPE-materials. In use-scenario practice, however, all processes will occur concurrently. Thus, SPE field performance evaluation including user-SPE interaction complementary to material testing is warranted. Results of laboratory testing for SPE-materials are reported as substance-specific breakthrough times and permeation rates. SPE field performance should be evaluated for reduction of either uptake or parameters that reflect the outcome of dermal exposure. Ideally, this should be based on the results of intervention-type workplace studies, for (e.g., assessment of exposure loading). The level of reduction can be expressed as a protection factor (ratio without/with SPE) for different parameters of dermal exposure or uptake. It is concluded that for evaluation of SPE-type performance, generic protection factors can be derived for substance-independent processes (e.g., reduction of exposure loading) but not for substance-specific reduction of uptake.

Discordant K-Ar and Young Exposure Dates for the Windjana Sandstone, Kimberley, Gale Crater, Mars

NASA Technical Reports Server (NTRS)

Vasconcelos, P. M.; Farley, K. A.; Malespin, C. A.; Mahaffy, P.; Ming, D.; McLennan, S. M.; Hurowitz, J. A.; Rice, Melissa S.

2016-01-01

K-Ar and noble gas surface exposure age measurements were carried out on the Windjana sandstone, Kimberley region, Gale Crater, Mars, by using the Sample Analysis at Mars instrument on the Curiosity rover. The sandstone is unusually rich in sanidine, as determined by CheMin X-ray diffraction, contributing to the high K2O concentration of 3.09 +/- 0.20 wt % measured by Alpha-Particle X-ray Spectrometer analysis. A sandstone aliquot heated to approximately 915 C yielded a K-Ar age of 627 +/- 50 Ma. Reheating this aliquot yielded no additional Ar. A second aliquot heated in the same way yielded a much higher K-Ar age of 1710 +/- 110 Ma. These data suggest incomplete Ar extraction from a rock with a K-Ar age older than 1710 Ma. Incomplete extraction at approximately 900 C is not surprising for a rock with a large fraction of K carried by Ar-retentive K-feldspar. Likely, variability in the exact temperature achieved by the sample from run to run, uncertainties in sample mass estimation, and possible mineral fractionation during transport and storage prior to analysis may contribute to these discrepant data. Cosmic ray exposure ages from He-3 and Ne-21 in the two aliquots are minimum values given the possibility of incomplete extraction. However, the general similarity between the He-3 (57 +/- 49 and 18 +/- 32 Ma, mean 30 Ma) and Ne-21 (2 +/- 32 and 83 +/- 24 Ma, mean 54 Ma) exposure ages provides no evidence for underextraction. The implied erosion rate at the Kimberley location is similar to that reported at the nearby Yellowknife Bay outcrop.

Cigarette smoke exposure reveals a novel role for the MEK/ERK1/2 MAPK pathway in regulation of CFTR

PubMed Central

Xu, Xiaohua; Balsiger, Robert; Tyrrell, Jean; Boyaka, Prosper N.; Tarran, Robert; Cormet-Boyaka, Estelle

2015-01-01

Background CFTR plays a key role in maintenance of lung fluid homeostasis. Cigarette smoke decreases CFTR expression in the lung but neither the mechanisms leading to CFTR loss, nor potential ways to prevent its loss have been identified to date. Methods The molecular mechanisms leading to down-regulation of CFTR by cigarette smoke were determined using pharmacologic inhibitors and silencing RNAs. Results Using human bronchial epithelial cells, here we show that cigarette smoke induces degradation of CFTR that is attenuated by the lysosomal inhibitors, but not proteasome inhibitors. Cigarette smoke can activate multiple signaling pathways in airway epithelial cells, including the MEK/Erk1/2 MAPK pathway regulating cell survival. Interestingly, pharmacological inhibition of the MEK/Erk1/2 MAPK pathway prevented the loss of plasma membrane CFTR upon cigarette smoke exposure. Similarly, decreased expression of Erk1/2 using silencing RNAs prevented the suppression of CFTR protein by cigarette smoke. Conversely, specific inhibitors of the JNK or p38 MAPK pathways had no effect on CFTR decrease after cigarette smoke exposure. In addition, inhibition of the MEK/Erk1/2 MAPK pathway prevented the reduction of the airway surface liquid observed upon cigarette smoke exposure of primary human airway epithelial cells. Finally, addition of the antioxidant NAC inhibited activation of Erk1/2 by cigarette smoke and precluded the cigarette smoke-induced decrease of CFTR. Conclusions These results show that the MEK/Erk1/2 MAPK pathway regulates plasma membrane CFTR in human airway cells. General Significance The MEK/Erk1/2 MAPK pathway should be considered as a target for strategies to maintain/restore CFTR expression in the lung of smokers. PMID:25697727

An investigation of the degradation of Fluorinated Ethylene Propylene (FEP) copolymer thermal blanketing materials aboard LDEF in the laboratory

NASA Technical Reports Server (NTRS)

Stiegman, A. E.; Brinza, David E.; Anderson, Mark S.; Minton, Timothy K.; Laue, Eric G.; Liang, Ranty H.

1991-01-01

Samples of fluorinated ethylene propylene copolymer thermal blanketing material, recovered from the Long Duration Exposure Facility (LDEF), were investigated to determine the nature and the extent of degradation due to exposure to the low-Earth-orbit environment. Samples recovered from the ram-facing direction of LDEF, which received vacuum-ultraviolet (VUV) radiation and atomic-oxygen impingement, and samples from the trailing edge, which received almost exclusively VUV exposure, were investigated by scanning electron microscopy and atomic force microscopy. The most significant result of this investigation was found on samples that received only VUV exposure. These samples possessed a hard, embrittled surface layer that was absent from the atomic-oxygen exposed sample and from unexposed control samples. This surface layer is believed to be responsible for the 'synergistic' effect between VUV and atomic oxygen. Overall, the investigation revealed dramatically different morphologies for the two samples. The sample receiving both atomic-oxygen and VUV exposure was deeply eroded and had a characteristic 'rolling' surface morphology, while the sample that received only VUV exposure showed mild erosion and a surface morphology characterized by sharp high-frequency peaks. The morphologies observed in the LDEF samples, including the embrittled surface layer, were successfully duplicated in the laboratory.

Cocaine-Induced Neurodevelopmental Deficits and Underlying Mechanisms

PubMed Central

Martin, Melissa M.; Graham, Devon L.; McCarthy, Deirdre M.; Bhide, Pradeep G.; Stanwood, Gregg D.

2017-01-01

Exposure to drugs early in life has complex and long-lasting implications for brain structure and function. This review summarizes work to date on the immediate and long-term effects of prenatal exposure to cocaine. In utero cocaine exposure produces disruptions in brain monoamines, particularly dopamine, during sensitive periods of brain development, and leads to permanent changes in specific brain circuits, molecules, and behavior. Here, we integrate clinical studies and significance with mechanistic preclinical studies, to define our current knowledge base and identify gaps for future investigation. PMID:27345015

Birth Outcomes Among Military Personnel Following Exposure to Documented Open-Air Burn Pits Before and During Pregnancy

DTIC Science & Technology

2012-06-01

of the parents’ exposure to the onset of pregnancy ( maternal model) or EDC ( paternal model), cumulative days of exposure to a burn pit region before...the infant’s date of birth ( maternal model) or EDC ( paternal model), and last exposed deployment, defined as the parent’s duty location (ie, Joint Base...in Table 1. Maternal age (ie, age of the deployer in the maternal model and the deployer’s spouse in the paternal model) was lower (ន years) among

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

USGS Publications Warehouse

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

2000-01-01

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

Surface and buried interfacial structures of epoxy resins used as underfills studied by sum frequency generation vibrational spectroscopy.

PubMed

Vázquez, Anne V; Holden, Brad; Kristalyn, Cornelius; Fuller, Mike; Wilkerson, Brett; Chen, Zhan

2011-05-01

Flip chip technology has greatly improved the performance of semiconductor devices, but relies heavily on the performance of epoxy underfill adhesives. Because epoxy underfills are cured in situ in flip chip semiconductor devices, understanding their surface and interfacial structures is critical for understanding their adhesion to various substrates. Here, sum frequency generation (SFG) vibrational spectroscopy was used to study surface and buried interfacial structures of two model epoxy resins used as underfills in flip chip devices, bisphenol A digylcidyl ether (BADGE) and 1,4-butanediol diglycidyl ether (BDDGE). The surface structures of these epoxies were compared before and after cure, and the orientations of their surface functional groups were deduced to understand how surface structural changes during cure may affect adhesion properties. Further, the effect of moisture exposure, a known cause of adhesion failure, on surface structures was studied. It was found that the BADGE surface significantly restructured upon moisture exposure while the BDDGE surface did not, showing that BADGE adhesives may be more prone to moisture-induced delamination. Lastly, although surface structure can give some insight into adhesion, buried interfacial structures more directly correspond to adhesion properties of polymers. SFG was used to study buried interfaces between deuterated polystyrene (d-PS) and the epoxies before and after moisture exposure. It was shown that moisture exposure acted to disorder the buried interfaces, most likely due to swelling. These results correlated with lap shear adhesion testing showing a decrease in adhesion strength after moisture exposure. The presented work showed that surface and interfacial structures can be correlated to adhesive strength and may be helpful in understanding and designing optimized epoxy underfill adhesives.

49 CFR 1248.5 - Report forms and date of filing.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 9 2013-10-01 2013-10-01 false Report forms and date of filing. 1248.5 Section 1248.5 Transportation Other Regulations Relating to Transportation (Continued) SURFACE TRANSPORTATION BOARD, DEPARTMENT OF TRANSPORTATION (CONTINUED) ACCOUNTS, RECORDS AND REPORTS FREIGHT COMMODITY STATISTICS § 1248.5 Report forms and date of filing. ...

The Effect of Evaporated Salt Solutions on the Optical Dating Properties of JSC Mars-1: "Seasoning" for a Mars Soil Simulant

NASA Astrophysics Data System (ADS)

Lepper, Kenneth

2009-08-01

Optically stimulated luminescence dating, or optical dating, is an established terrestrial geochronometric technique that is being adapted to date sedimentary deposits and landforms on the surface of Mars. Recent discoveries have highlighted the astrobiological significance and occurrence of halite on the surface of Mars. The objective of the experiments in this study was to create a simplistic analogue of the sedimentary material that would result from evaporation of ion-containing pore water out of martian regolith and evaluate the influence the evaporated salts would have on in situ optical dating of silicate sediments. The radiation dose response, as measured by infrared stimulated luminescence (IRSL), from evaporated mixtures of JSC Mars-1 and solutions of sodium chloride and calcium sulfate was documented. The results suggest that the presence of CaSO4 and NaCl within the aggregated particles does not have adverse effects on IRSL dose response and that aggregates of this type exhibit dose response characteristics that are appropriate for optical dating.

Symmetric Imidazolium-Based Paramagnetic Ionic Liquids

DTIC Science & Technology

2017-11-29

REPORT DATE 2. REPORT TYPE 3 . DATES COVERED (From - To) 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER...ADDRESS(ES) 12. DISTRIBUTION/AVAILABILITY STATEMENT 13. SUPPLEMENTARY NOTES 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: a...Number: 17717 3 Motivation •SLIPS at high temperatures •ILs: stable at high temperatures but high surface tension •Alkyl chains to reduce surface tension

Patterning of Biomolecules on Plasma-Enhanced Chemical Vapor Deposited Generated Surfaces

DTIC Science & Technology

2006-01-01

utilized conventional 1 -Ethyl- 3 -[ 3 - dimethylaminopropyl ]carbodiimide hydrochloride (EDC) to couple carboxyl groups to primary amines and thiol oxidation...RETURN YOUR FORM TO THE ABOVE ADDRESS. 1 . REPORT DATE (DD-MM-YY) 2. REPORT TYPE 3 . DATES COVERED (From - To) January 2006 Journal Article Preprint...morphology, allowing for robust surface deposited 3 materials. More specifically, bulk pp-benzene shows less than 1 % sol fraction when immersed in

40 CFR Appendix Vii to Part 268 - LDR Effective Dates of Surface Disposed Prohibited Hazardous Wastes

Code of Federal Regulations, 2012 CFR

2012-07-01

... Dates of Surface Disposed Wastes (Non-Soil and Debris) Regulated in the LDRS a—Comprehensive List Waste... radioactive wastes June 30, 1994. F039 Wastewater Aug. 8, 1990. F039 Nonwastewater May 8, 1992. K001 (organics.... K085 All Aug. 8, 1990. K086 (organics) b All Aug. 8, 1988. K086 All others Aug. 8, 1988. K087 All Aug...

40 CFR Appendix Vii to Part 268 - LDR Effective Dates of Surface Disposed Prohibited Hazardous Wastes

Code of Federal Regulations, 2010 CFR

2010-07-01

... Dates of Surface Disposed Wastes (Non-Soil and Debris) Regulated in the LDRS a—Comprehensive List Waste... radioactive wastes June 30, 1994. F039 Wastewater Aug. 8, 1990. F039 Nonwastewater May 8, 1992. K001 (organics.... K085 All Aug. 8, 1990. K086 (organics) b All Aug. 8, 1988. K086 All others Aug. 8, 1988. K087 All Aug...

40 CFR Appendix Vii to Part 268 - LDR Effective Dates of Surface Disposed Prohibited Hazardous Wastes

Code of Federal Regulations, 2014 CFR

2014-07-01

... Dates of Surface Disposed Wastes (Non-Soil and Debris) Regulated in the LDRS a—Comprehensive List Waste... radioactive wastes June 30, 1994. F039 Wastewater Aug. 8, 1990. F039 Nonwastewater May 8, 1992. K001 (organics.... K085 All Aug. 8, 1990. K086 (organics) b All Aug. 8, 1988. K086 All others Aug. 8, 1988. K087 All Aug...

40 CFR Appendix Vii to Part 268 - LDR Effective Dates of Surface Disposed Prohibited Hazardous Wastes

Code of Federal Regulations, 2011 CFR

2011-07-01

... Dates of Surface Disposed Wastes (Non-Soil and Debris) Regulated in the LDRS a—Comprehensive List Waste... radioactive wastes June 30, 1994. F039 Wastewater Aug. 8, 1990. F039 Nonwastewater May 8, 1992. K001 (organics.... K085 All Aug. 8, 1990. K086 (organics) b All Aug. 8, 1988. K086 All others Aug. 8, 1988. K087 All Aug...

40 CFR Appendix Vii to Part 268 - LDR Effective Dates of Surface Disposed Prohibited Hazardous Wastes

Code of Federal Regulations, 2013 CFR

2013-07-01

... Dates of Surface Disposed Wastes (Non-Soil and Debris) Regulated in the LDRS a—Comprehensive List Waste... radioactive wastes June 30, 1994. F039 Wastewater Aug. 8, 1990. F039 Nonwastewater May 8, 1992. K001 (organics.... K085 All Aug. 8, 1990. K086 (organics) b All Aug. 8, 1988. K086 All others Aug. 8, 1988. K087 All Aug...

Earth Observations taken by the Expedition 25 crew

NASA Image and Video Library

2010-10-06

ISS025-E-006163 (6 Oct. 2010) --- Nevado Coropuna, Peru is featured in this image photographed by an Expedition 25 crew member on the International Space Station. Nevado (“snowy” or “snowy peak” in Spanish) Coropuna is the highest volcanic peak in Peru – the summit elevation is 6,377 meters above sea level. Rather than being a single stratovolcano, Coropuna is a volcanic complex of numerous summit cones. The complex covers an area of 240 square kilometers within the Ampato mountain range (Cordillera Ampato) in southeast-central Peru. While the exact date of the volcano’s last eruption is not known, lava flows (black, at center and upper left) along the northern, southern, and western flanks of the complex are thought to have been emplaced during the early Holocene Epoch – the current geologic time period which began approximately 12,000 years ago, according to scientists. Coropuna also hosts several summit glaciers and icefields (white to gray, center) that contrast sharply with the dark rock outcrops and surface deposits at lower elevations. Glacial deposits and lateral moraines on the flanks of Coropuna indicate that glaciers once extended to much lower elevations than are observed today. Scientists believe that careful mapping and surface exposure age-dating of these glacial deposits and landforms provides data on the timing of ice advances and retreats in the tropics near the end of the Pleistocene Epoch (extending from approximately 2.5 million to approximately 12,000 years ago). In turn, this information can be compared with other paleoclimate records to obtain a better understanding of how Earth’s global climate has changed over geologic time.

Evidence for the Buried "Pre-Noachian" Crust Pre-Dating the Oldest Observed Surface Units on Mars

NASA Technical Reports Server (NTRS)

Frey, H. V.; Frey, E. L.; Hartmann, W. K.; Tanaka, K. L. T.

2003-01-01

MOLA gridded data shows clear evidence for Quasi-Circular Depressions not visible on images in Early Noachian (EN) terrain units on Mars. We suggest these are buried impact basins that pre-date the superimposed craters whose high density makes these EN units the oldest visible at the surface of Mars. There is crust older than the oldest visible terrain units on Mars, and these EN units cannot date from 4.6 BYA. These and other Noa-chian units have similar total (visible + buried) crater retention ages, suggesting a common "pre-Noachian" crustal age OR crater saturation beyond which we cannot see.

Evidence for Buried "Pre-Noachian" Crust Pre-Dating the Oldest Observed Surface Units on Mars

NASA Technical Reports Server (NTRS)

Frey, H. V.; Frey, E. L.; Hartmann, W. K.; Tanaka, K. L. T.

2004-01-01

MOLA gridded data shows clear evidence for Quasi-Circular Depressions not visible on images in Early Noachian (EN) terrain units on Mars. We suggest these are buried impact basins that pre-date the superimposed craters whose high density makes these EN units the oldest visible at the surface of Mars. There is crust older than the oldest visible terrain units on Mars, and these EN units cannot date from 4.6 BYA. These and other Noachian units have similar total (visible + buried) crater retention ages, suggesting a common "pre-Noachian" crustal age OR crater saturation beyond which we cannot see.

Surface phenology and satellite sensor-derived onset of greenness: An initial comparison

USGS Publications Warehouse

Schwartz, Mark D.; Reed, Bradley C.

1999-01-01

The objective of this work was to document the utility of phenological data derived from satellite sensors by comparing them with modelled phenology. Surface phenological model outputs (first leaf and first bloom dates) were correlated positively with satellite sensor-derived start of season (SOS) dates for 1991-1995 across the eastern United States. The correlation was highest for forest (r 0.62 for deciduous trees and 0.64 for mixed woodland) and tall grass (r 0.46) and lowest for short grass (r 0.37). The average correlation over all land cover types was 0.61. Average SOS dates were consistently earlier than Spring Index dates across all land cover types. This finding and limited native tree phenology data suggest that the SOS technique detects understorey green-up in the forest rather than overstorey species. The biweekly temporal resolution of the satellite sensor data placed an upper limit on prediction accuracy; thus, year-to-year variations at individual sites were typically small. Nevertheless, the correct biweek SOS could be identified from the surface models 61% of the time, and 1 biweek 96% of the time. Further temporal refinement of the satellite sensor measurements is necessary in order to connect them with surface phenology adequately and to develop links among 'green wave' components in selected biomes.

Statistical characterization of surface features from tungsten-coated divertor inserts in the DIII-D Metal Rings Campaign

NASA Astrophysics Data System (ADS)

Adams, Jacob; Unterberg, Ezekial; Chrobak, Christopher; Stahl, Brian; Abrams, Tyler

2017-10-01

Continuing analysis of tungsten-coated inserts from the recent DIII-D Metal Rings Campaign utilizes a statistical approach to study carbon migration and deposition on W surfaces and to characterize the pre- versus post-exposure surface morphology. A TZM base was coated with W using both CVD and PVD and allowed for comparison between the two coating methods. The W inserts were positioned in the lower DIII-D divertor in both the upper (shelf) region and lower (floor) region and subjected to multiple plasma shots, primarily in H-mode. Currently, the post-exposure W inserts are being characterized using SEM/EDX to qualify the surface morphology and to quantify the surface chemical composition. In addition, profilometry is being used to measure the surface roughness of the inserts both before and after plasma exposure. Preliminary results suggest a correlation between the pre-exposure surface roughness and the level of carbon deposited on the surface. Furthermore, ongoing in-depth analysis may reveal insights into the formation mechanism of nanoscale bumps found in the carbon-rich regions of the W surfaces that have not yet been explained. Work supported in part by US DoE under the Science Undergraduate Laboratory Internship (SULI) program and under DE-FC02-04ER54698.

The relationship of near-surface active faulting to megathrust splay fault geometry in Prince William Sound, Alaska

NASA Astrophysics Data System (ADS)

Finn, S.; Liberty, L. M.; Haeussler, P. J.; Northrup, C.; Pratt, T. L.

2010-12-01

We interpret regionally extensive, active faults beneath Prince William Sound (PWS), Alaska, to be structurally linked to deeper megathrust splay faults, such as the one that ruptured in the 1964 M9.2 earthquake. Western PWS in particular is unique; the locations of active faulting offer insights into the transition at the southern terminus of the previously subducted Yakutat slab to Pacific plate subduction. Newly acquired high-resolution, marine seismic data show three seismic facies related to Holocene and older Quaternary to Tertiary strata. These sediments are cut by numerous high angle normal faults in the hanging wall of megathrust splay. Crustal-scale seismic reflection profiles show splay faults emerging from 20 km depth between the Yakutat block and North American crust and surfacing as the Hanning Bay and Patton Bay faults. A distinct boundary coinciding beneath the Hinchinbrook Entrance causes a systematic fault trend change from N30E in southwestern PWS to N70E in northeastern PWS. The fault trend change underneath Hinchinbrook Entrance may occur gradually or abruptly and there is evidence for similar deformation near the Montague Strait Entrance. Landward of surface expressions of the splay fault, we observe subsidence, faulting, and landslides that record deformation associated with the 1964 and older megathrust earthquakes. Surface exposures of Tertiary rocks throughout PWS along with new apatite-helium dates suggest long-term and regional uplift with localized, fault-controlled subsidence.

Effect of Atomic Oxygen Exposure on Surface Resistivity Change of Spacecraft Insulator Material

NASA Astrophysics Data System (ADS)

Mundari, Noor Danish Ahrar; Khan, Arifur Rahman; Chiga, Masaru; Okumura, Teppei; Masui, Hirokazu; Iwata, Minoru; Toyoda, Kazuhiro; Cho, Mengu

Spacecraft surface charging can lead to arcing and a loss of electricity generation capability in solar panels or even loss of a satellite. The charging problem may be further aggravated by atomic oxygen (AO) exposure in Low Earth orbits, which modifies the surface of materials like polyimide, Teflon, anti-reflective coatings, cover glass etc, used on satellite surfaces, affecting materials properties, such as resistivity, secondary electron emissivity and photo emission, which govern the charging behavior. These properties are crucial input parameters for spacecraft charging analysis. To study the AO exposure effect on charging governing properties, an atomic oxygen exposure facility based on laser detonation of oxygen was built. The facility produces AO with a peak velocity value around 10-12km/s and a higher flux than that existing in orbit. After exposing the polyimide test material to the equivalent of 10 years of AO fluence at an altitude of 700-800 km, surface charging properties like surface resistivity and volume resistivity were measured. The measurement was performed in a vacuum using the charge storage decay method at room temperature, which is considered the most appropriate for measuring resistivity for space applications. The results show that the surface resistivity increases and the volume resistivity remains almost the same for the AO exposure fluence of 5.4×1018 atoms cm-2.

Chemical characterization of selected LDEF polymeric materials

NASA Technical Reports Server (NTRS)

Young, Philip R.; Slemp, Wayne S.

1991-01-01

Chemical characterization of selected polymeric materials which received exposure on the Long Duration Exposure Facility (LDEF) is reported. The specimens examined include silvered fluorinated ethylene propylene Teflon thermal blanket material, polysulfone, epoxy, polyimide matrix resin/graphite fiber reinforced composites, and several high performance polymer films. These specimens came from numerous LDEF locations, and thus received different environmental exposures. The results to date show no significant change at the molecular level in the polymer that survived exposure. Scanning electron and scanning tunneling microscopes show resin loss and a texturing of some specimens which resulted in a change in optical properties. The potential effect of a silicon-containing molecular contamination on these materials is addressed. The possibility of continued post-exposure degradation of some polymeric films is also proposed.

Migration of Beryllium via Multiple Exposure Pathways among Work Processes in Four Different Facilities.

PubMed

Armstrong, Jenna L; Day, Gregory A; Park, Ji Young; Stefaniak, Aleksandr B; Stanton, Marcia L; Deubner, David C; Kent, Michael S; Schuler, Christine R; Virji, M Abbas

2014-01-01

Inhalation of beryllium is associated with the development of sensitization; however, dermal exposure may also be important. The primary aim of this study was to elucidate relationships among exposure pathways in four different manufacturing and finishing facilities. Secondary aims were to identify jobs with increased levels of beryllium in air, on skin, and on surfaces; identify potential discrepancies in exposure pathways, and determine if these are related to jobs with previously identified risk. Beryllium was measured in air, on cotton gloves, and on work surfaces. Summary statistics were calculated and correlations among all three measurement types were examined at the facility and job level. Exposure ranking strategies were used to identify jobs with higher exposures. The highest air, glove, and surface measurements were observed in beryllium metal production and beryllium oxide ceramics manufacturing jobs that involved hot processes and handling powders. Two finishing and distribution facilities that handle solid alloy products had lower exposures than the primary production facilities, and there were differences observed among jobs. For all facilities combined, strong correlations were found between air-surface (rp ≥ 0.77), glove-surface (rp ≥ 0.76), and air-glove measurements (rp ≥ 0.69). In jobs where higher risk of beryllium sensitization or disease has been reported, exposure levels for all three measurement types were higher than in jobs with lower risk, though they were not the highest. Some jobs with low air concentrations had higher levels of beryllium on glove and surface wipe samples, suggesting a need to further evaluate the causes of the discrepant levels. Although such correlations provide insight on where beryllium is located throughout the workplace, they cannot identify the direction of the pathways between air, surface, or skin. Ranking strategies helped to identify jobs with the highest combined air, glove, and/or surface exposures. All previously identified high-risk jobs had high air concentrations, dermal mass loading, or both, and none had low dermal and air. We have found that both pathways are relevant. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: a file describing the forms of beryllium materials encountered during production and characteristics of the aerosols by process areas.].

Biological Effects of Nuclear Explosions (BENE) Domain Guide

DTIC Science & Technology

2012-09-01

DATE (DD-MM-YYYY) 2. REPORT TYPE 3. DATES COVERED (From – To) Technical Report October 2004-April 2005 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER...greatly increased in the nearby region because increasing amounts of contaminated earth and debris are sucked up into the radioactive cloud. In the case...or a denial scenario involving radioisotopes will be non-uniform exposure with various doses and dose rates producing very large variations in

Establishing and applying of a coupled individual based model of edible jellyfish(Rhopilema esculentum Kishinouye) releasing in the Liaodong Bay

NASA Astrophysics Data System (ADS)

Yin, Liping; Qiao, Fangli

2017-04-01

A three-dimensional circulation-surface wave coupled hydrodynamic model coupled with an individual-based jellyfish model was established to investigate the influence of physical process on edible jellyfish releasing stock enhancement in Liaodong Bay. Sensitivity experiments show that the wind intensity and direction have both direct and indirect impacts on the distribution of the jellyfish. When the wind is strong, the surface current in Liaodong Bay has the same direction of the wind. Under the co-effect of the ocean current transport and the surface wind transport, the jellyfish inhabits in the northeast of Liaodong bay, which is consistent with the observation. In the circumstance of weak wind, the circulation is clockwise and the jellyfish will spread around the 5m isobaths following the circulation. Research of the jellyfish distribution shows that the releasing jellyfish will stay in Liaodong bay in its whole life history, hence Liaodong Bay is a quite suitable area for enhancement releasing. The influence of the temperature on releasing region and date is also investigated. The threshold date during 2008 to 2016 is calculated, which is the date when the temperature of water within 10m isobaths in Liaodong Bay rises up to 15oC. In 2010, the threshold date came about one week later while the medusa releasing date remains the same in 2009. As a result, higher fatality rate of medusa caused by the cold water resulted in lower recapture rate in 2010. Therefore, the releasing date and location should be varied according to environmental conditions. The threshold date tends to appear earlier during 2008 to 2016, which suggests an earlier releasing date. In summer, due to the cold water mass intrusion from the south, the releasing date in the north area should be earlier than in the south.

Surface microhardness of a resin composite exposed to a "first-generation" LED curing lamp, in vitro.

PubMed

Keogh, Pauraic; Ray, Noel J; Lynch, Christopher D; Burke, Francis M; Hannigan, Ailish

2004-12-01

This investigation determined the minimum exposure times consistent with optimised surface microhardness parameters for a commercial resin composite cured using a "first-generation" light-emitting diode activation lamp. Disk specimens were exposed and surface microhardness numbers measured at the top and bottom surfaces for elapsed times of 1 hour and 24 hours. Bottom/top microhardness number ratios were also calculated. Most microhardness data increased significantly over the elapsed time interval but microhardness ratios (bottom/top) were dependent on exposure time only. A minimum exposure of 40 secs is appropriate to optimise microhardness parameters for the combination of resin composite and lamp investigated.

Remotely Sensed Thermal Anomalies in Western Colorado

DOE Data Explorer

Khalid Hussein

2012-02-01

This layer contains the areas identified as areas of anomalous surface temperature from Landsat satellite imagery in Western Colorado. Data was obtained for two different dates. The digital numbers of each Landsat scene were converted to radiance and the temperature was calculated in degrees Kelvin and then converted to degrees Celsius for each land cover type using the emissivity of that cover type. And this process was repeated for each of the land cover types (open water, barren, deciduous forest and evergreen forest, mixed forest, shrub/scrub, grassland/herbaceous, pasture hay, and cultivated crops). The temperature of each pixel within each scene was calculated using the thermal band. In order to calculate the temperature an average emissivity value was used for each land cover type within each scene. The NLCD 2001 land cover classification raster data of the zones that cover Colorado were downloaded from USGS site and used to identify the land cover types within each scene. Areas that had temperature residual greater than 2o, and areas with temperature equal to 1o to 2o, were considered Landsat modeled very warm and warm surface exposures (thermal anomalies), respectively. Note: 'o' is used in this description to represent lowercase sigma.

Interior surface materials in the home and the development of bronchial obstruction in young children in Oslo, Norway.

PubMed Central

Jaakkola, J J; Oie, L; Nafstad, P; Botten, G; Samuelsen, S O; Magnus, P

1999-01-01

OBJECTIVES: This study assessed the role of polyvinyl chloride (PVC) plastics and textile materials in the home in the development of bronchial obstruction during the first 2 years of life. METHODS: The study was a matched pair case-control study based on a cohort of 3754 newborns in Oslo in 1992 and 1993 who were followed up for 2 years. The case group consisted of 251 children with bronchial obstruction; the control group was matched one-to-one for date of birth. RESULTS: In conditional logistic regression analysis, the risk of bronchial obstruction was related to the presence of PVC flooring (adjusted odds ratio [OR] = 1.89; 95% confidence interval [CI] = 1.14, 3.14) and textile wall materials (adjusted OR = 1.58; 95% CI = 0.98, 2.54). The reference category was wood or parquet flooring and painted walls and ceiling. Further analysis revealed an exposure-response relationship between the assessed amount of PVC and other plasticizer-containing surface materials and the risk of bronchial obstruction. CONCLUSIONS: This study provides new evidence of the role of PVC and textile wall materials in the development of bronchial obstruction in young children. PMID:9949747

Interior surface materials in the home and the development of bronchial obstruction in young children in Oslo, Norway.

PubMed

Jaakkola, J J; Oie, L; Nafstad, P; Botten, G; Samuelsen, S O; Magnus, P

1999-02-01

This study assessed the role of polyvinyl chloride (PVC) plastics and textile materials in the home in the development of bronchial obstruction during the first 2 years of life. The study was a matched pair case-control study based on a cohort of 3754 newborns in Oslo in 1992 and 1993 who were followed up for 2 years. The case group consisted of 251 children with bronchial obstruction; the control group was matched one-to-one for date of birth. In conditional logistic regression analysis, the risk of bronchial obstruction was related to the presence of PVC flooring (adjusted odds ratio [OR] = 1.89; 95% confidence interval [CI] = 1.14, 3.14) and textile wall materials (adjusted OR = 1.58; 95% CI = 0.98, 2.54). The reference category was wood or parquet flooring and painted walls and ceiling. Further analysis revealed an exposure-response relationship between the assessed amount of PVC and other plasticizer-containing surface materials and the risk of bronchial obstruction. This study provides new evidence of the role of PVC and textile wall materials in the development of bronchial obstruction in young children.

Developing OSL Geological Dating Techniques for Use on Future Missions to Mars

NASA Technical Reports Server (NTRS)

Blair, M. W.; Kalchgruber, R.; Deo, S.; McKeever, S. W. S.

2005-01-01

The surface of Mars has been subject to aeolian, fluvial, and periglacial activity in the (relatively) recent past. Unfortunately, chronological dating of recent events on Mars is difficult as the errors associated with crater counting are comparable to younger ages (approx. 1 Ma). Consequently, techniques to quantify the ages of geological processes on Mars have become an important area of research. Optically stimulated luminescence (OSL) dating is one candidate technique for in-situ dating of the deposition of Martian surface sediments. This method can aid in developing a geological and climatic history of the last million years on Mars. The current paper addresses some of the challenges and progress associated with developing OSL as a viable in-situ dating technique for Mars. Some of the challenges include the mineral composition, the effectiveness of solar resetting under Martian conditions, the temperature regime, and determining the natural dose rate on Mars. All of these topics are currently under investigation, and some preliminary results are presented.

New and revised 14C dates for Hawaiian surface lava flows: Paleomagnetic and geomagnetic implications

USGS Publications Warehouse

Pressline, N.; Trusdell, F.A.; Gubbins, David

2009-01-01

Radiocarbon dates have been obtained for 30 charcoal samples corresponding to 27 surface lava flows from the Mauna Loa and Kilauea volcanoes on the Island of Hawaii. The submitted charcoal was a mixture of fresh and archived material. Preparation and analysis was undertaken at the NERC Radiocarbon Laboratory in Glasgow, Scotland, and the associated SUERC Accelerator Mass Spectrometry facility. The resulting dates range from 390 years B.P. to 12,910 years B.P. with corresponding error bars an order of magnitude smaller than previously obtained using the gas-counting method. The new and revised 14C data set can aid hazard and risk assessment on the island. The data presented here also have implications for geomagnetic modelling, which at present is limited by large dating errors. Copyright 2009 by the American Geophysical Union.

Occupational exposure to wood dust and risk of nasal and nasopharyngeal cancer: A case-control study among men in four nordic countries-With an emphasis on nasal adenocarcinoma.

PubMed

Siew, Sie Sie; Martinsen, Jan Ivar; Kjaerheim, Kristina; Sparén, Pär; Tryggvadottir, Laufey; Weiderpass, Elisabete; Pukkala, Eero

2017-12-15

The current study aims to provide stronger evidence to aid in our understanding of the role of cumulative occupational exposure to (softwood-dominated) mixed wood dust in aetiology of nasal cancer. We included broad exposure occurred in a range of wood-processing occupation across varied industries in four Nordic countries. A population-based case-control study was conducted on all male cases with nasal adenocarcinoma (393 cases), other types of nasal cancer (2,446) and nasopharyngeal cancer (1,747) diagnosed in Finland, Sweden, Norway and Iceland between 1961 and 2005. For each case, five male controls, who were alive at the time of diagnosis of the case (index date), were randomly selected, matched by birth-year and country. Cumulative exposures (CE)s to wood dust and formaldehyde before the index date were quantified based on a job-exposure matrix linked to occupational titles derived from population censuses. Hazard ratios (HRs) for the CE of wood dust were estimated by conditional logistic regression, adjusted for CE to formaldehyde and 95% confidence intervals (CIs) were calculated. There was an increasing risk of nasal adenocarcinoma related to wood dust exposure. The HR in the highest CE category of wood dust (≥ 28.82 mg/m 3 -years) was 16.5 (95% CI 5.05-54.1). Neither nonadenocarcinoma of the nose nor nasopharyngeal cancer could be linked to wood dust exposure. CE to softwood-dominated mixed wood dusts is strongly linked with elevated risk in nasal adenocarcinoma but not with other types of nasal or nasopharyngeal cancer. © 2017 UICC.

The Impacts of Sexual Media Exposure on Adolescent and Emerging Adults' Dating and Sexual Violence Attitudes and Behaviors: A Critical Review of the Literature.

PubMed

Rodenhizer, Kara Anne E; Edwards, Katie M

2017-01-01

Dating violence (DV) and sexual violence (SV) are widespread problems among adolescents and emerging adults. A growing body of literature demonstrates that exposure to sexually explicit media (SEM) and sexually violent media (SVM) may be risk factors for DV and SV. The purpose of this article is to provide a systematic and comprehensive literature review on the impact of exposure to SEM and SVM on DV and SV attitudes and behaviors. A total of 43 studies utilizing adolescent and emerging adult samples were reviewed, and collectively the findings suggest that (1) exposure to SEM and SVM is positively related to DV and SV myths and more accepting attitudes toward DV and SV; (2) exposure to SEM and SVM is positively related to actual and anticipated DV and SV victimization, perpetration, and bystander nonintervention; (3) SEM and SVM more strongly impact men's DV and SV attitudes and behaviors than women's DV and SV attitudes and behaviors; and (4) preexisting attitudes related to DV and SV and media preferences moderate the relationship between SEM and SVM exposure and DV and SV attitudes and behaviors. Future studies should strive to employ longitudinal and experimental designs, more closely examine the mediators and moderators of SEM and SVM exposure on DV and SV outcomes, focus on the impacts of SEM and SVM that extend beyond men's use of violence against women, and examine the extent to which media literacy programs could be used independently or in conjunction with existing DV and SV prevention programs to enhance effectiveness of these programming efforts.

The ID-KArD technique: In-situ dating on Mars

NASA Astrophysics Data System (ADS)

Cartwright, J. A.; Farley, K. A.; Hurowitz, J.; Asimow, P. D.; Jacobson, N. S.

2013-12-01

The ability to measure absolute ages on the Martian surface is crucial for understanding the planet's evolution. A detailed geological history of the Moon has been determined through analysis of returned samples from specific units, and relative ages calculated by crater counting techniques. However, without returned samples or in-situ dating analyses, we lack absolute age markers for Mars and thus cannot accurately or precisely date its well-documented surface. Instead, we have relied on an estimated Mars/Moon cratering ratio and relative crater counting techniques in an attempt to calculate surface ages and classify geological units. The use of such relative parameters diminishes the precision and accuracy for surface age calculations, and thus highlights the need for independent age determinations from returned samples or in-situ dating. In this research, we describe our technique - ID-KArD (Isotope Dilution K-Ar Dating) - intended for in-situ age dating of geological units on the Martian surface. ID-KArD resolves two challenges that have previously obstructed in-situ age dating on Mars: 1) High fusion temperatures are avoided with the use of a lithium-borate flux; 2) Sample mass measurement is not required, due to the addition of an isotope dilution doubly-spiked glass. The glass has a known 39Ar/41K ratio, which removes the need for concentration measurements. Thus, only isotope ratios are required for a K-Ar age determination. ID-KArD has the potential to address Mars chronology inaccuracies, and would be a suitable technique for consideration on future missions. In the first phase of ID-KArD proof of concept, we selected a Viluy trap basalt (K2O ~ 0.7 wt%), with concordant K-Ar and Ar-Ar ages of 354.3 × 3.5 and 357.7 × 1.4 Ma respectively (Courtillot et al., 2010). An aliquot was combined into a crucible with the flux and the spike glass for separate Ar (MAP 215:50, Caltech), followed by K (KEMS, GRC) isotopic analysis. Combining our results, we obtained an age of 351 × 19 Ma (Farley et al., 2013), in good agreement with the previously published ages. For the second phase, we have designed and built a single instrument, capable of analysing both Ar and K from a single sample. The instrument includes two ionisation sources for separate K (thermal) and Ar (electron impact) ionsiation, and a quadrupole mass spectrometer. In addition, we have designed a sample heating mechanism that allows degassing of flux prior to sample addition, and achieves temperatures in the range of the SAM oven on Curiosity. Thus far, the instrument has successfully measured both isotopic systems, and following further testing in the coming weeks, we will date Martian surface analogues, age standards, and finally meteoritic material.

Elevated Radiation Exposure Associated With Above Surface Flat Detector Mini C-Arm Use.

PubMed

Martin, Dennis P; Chapman, Talia; Williamson, Christopher; Tinsley, Brian; Ilyas, Asif M; Wang, Mark L

2017-11-01

This study aims to test the hypothesis that: (1) radiation exposure is increased with the intended use of Flat Surface Image Intensifier (FSII) units above the operative surface compared with the traditional below-table configuration; (2) this differential increases in a dose-dependent manner; and (3) radiation exposure varies with body part and proximity to the radiation source. A surgeon mannequin was seated at a radiolucent hand table, positioned for volar distal radius plating. Thermoluminescent dosimeters measured exposure to the eyes, thyroid, chest, hand, and groin, for 1- and 15-minute trials from a mini C-arm FSII unit positioned above and below the operating surface. Background radiation was measured by control dosimeters placed within the operating theater. At 1-minute of exposure, hand and eye dosages were significantly greater with the flat detector positioned above the table. At 15-minutes of exposure, hand radiation dosage exceeded that of all other anatomic sites with the FSII in both positions. Hand exposure was increased in a dose-dependent manner with the flat detector in either position, whereas groin exposure saw a dose-dependent only with the flat detector beneath the operating table. These findings suggest that the surgeon's hands and eyes may incur greater radiation exposure compared with other body parts, during routine mini C-arm FSII utilization in its intended position above the operating table. The clinical impact of these findings remains unclear, and future long-term radiation safety investigation is warranted. Surgeons should take precautions to protect critical body parts, particularly when using FSII technology above the operating with prolonged exposure time.

COMMON ISSUES IN HUMAN AND ECOSYSTEM EXPOSURE ASSESSMENT: THE SIGNIFICANCE OF PARTITIONING, KINETICS, AND UPTAKE AT BIOLOGICAL EXCHANGE SURFACES

EPA Science Inventory

Exogenous chemicals enter organisms through critical surfaces in the lung, gills, gut, and skin. Transfer across these boundaries is the first step in characterizing the ratio of tissue dose to external exposure. Surface processes and fugacity are important elements of both human...

Natural Sunlight Shapes Crude Oil-Degrading Bacterial Communities in Northern Gulf of Mexico Surface Waters

PubMed Central

Bacosa, Hernando P.; Liu, Zhanfei; Erdner, Deana L.

2015-01-01

Following the Deepwater Horizon (DWH) spill in 2010, an enormous amount of oil was observed in the deep and surface waters of the northern Gulf of Mexico. Surface waters are characterized by intense sunlight and high temperature during summer. While the oil-degrading bacterial communities in the deep-sea plume have been widely investigated, the effect of natural sunlight on those in oil polluted surface waters remains unexplored to date. In this study, we incubated surface water from the DWH site with amendments of crude oil, Corexit dispersant, or both for 36 days under natural sunlight in the northern Gulf of Mexico. The bacterial community was analyzed over time for total abundance, density of alkane and polycyclic aromatic hydrocarbon degraders, and community composition via pyrosequencing. Our results showed that, for treatments with oil and/or Corexit, sunlight significantly reduced bacterial diversity and evenness and was a key driver of shifts in bacterial community structure. In samples containing oil or dispersant, sunlight greatly reduced abundance of the Cyanobacterium Synechococcus but increased the relative abundances of Alteromonas, Marinobacter, Labrenzia, Sandarakinotalea, Bartonella, and Halomonas. Dark samples with oil were represented by members of Thalassobius, Winogradskyella, Alcanivorax, Formosa, Pseudomonas, Eubacterium, Erythrobacter, Natronocella, and Coxiella. Both oil and Corexit inhibited the Candidatus Pelagibacter with or without sunlight exposure. For the first time, we demonstrated the effects of light in structuring microbial communities in water with oil and/or Corexit. Overall, our findings improve understanding of oil pollution in surface water, and provide unequivocal evidence that sunlight is a key factor in determining bacterial community composition and dynamics in oil polluted marine waters. PMID:26648916

Natural Sunlight Shapes Crude Oil-Degrading Bacterial Communities in Northern Gulf of Mexico Surface Waters.

PubMed

Bacosa, Hernando P; Liu, Zhanfei; Erdner, Deana L

2015-01-01

Following the Deepwater Horizon (DWH) spill in 2010, an enormous amount of oil was observed in the deep and surface waters of the northern Gulf of Mexico. Surface waters are characterized by intense sunlight and high temperature during summer. While the oil-degrading bacterial communities in the deep-sea plume have been widely investigated, the effect of natural sunlight on those in oil polluted surface waters remains unexplored to date. In this study, we incubated surface water from the DWH site with amendments of crude oil, Corexit dispersant, or both for 36 days under natural sunlight in the northern Gulf of Mexico. The bacterial community was analyzed over time for total abundance, density of alkane and polycyclic aromatic hydrocarbon degraders, and community composition via pyrosequencing. Our results showed that, for treatments with oil and/or Corexit, sunlight significantly reduced bacterial diversity and evenness and was a key driver of shifts in bacterial community structure. In samples containing oil or dispersant, sunlight greatly reduced abundance of the Cyanobacterium Synechococcus but increased the relative abundances of Alteromonas, Marinobacter, Labrenzia, Sandarakinotalea, Bartonella, and Halomonas. Dark samples with oil were represented by members of Thalassobius, Winogradskyella, Alcanivorax, Formosa, Pseudomonas, Eubacterium, Erythrobacter, Natronocella, and Coxiella. Both oil and Corexit inhibited the Candidatus Pelagibacter with or without sunlight exposure. For the first time, we demonstrated the effects of light in structuring microbial communities in water with oil and/or Corexit. Overall, our findings improve understanding of oil pollution in surface water, and provide unequivocal evidence that sunlight is a key factor in determining bacterial community composition and dynamics in oil polluted marine waters.

Surface morphology changes to tungsten under exposure to He ions from an electron cyclotron resonance plasma source

NASA Astrophysics Data System (ADS)

Donovan, David; Buchenauer, Dean; Whaley, Josh; Friddle, Raymond; Wright, Graham

2014-10-01

Exposure of tungsten to low energy (<100 eV) helium plasmas at temperatures between 900-1900 K in both laboratory experiments and tokamaks has been shown to cause severe nanoscale modification of the near surface resulting the growth of tungsten tendrils. We are exploring the potential for using a compact ECR plasma in situ with scanning tunneling microscopy (STM) to investigate the early stages of helium induced tungsten migration. Here we report on characterization of the plasma source for helium plasmas with a desired ion flux of ~1 × 1019 ions m-2 s-1 and the surface morphology changes seen on the exposed tungsten surfaces. Exposures of polished tungsten discs have been performed and characterized using SEM, AFM, and FIB cross section imaging. Bubbles have been seen on the exposed tungsten surface and in sub-surface cross sections growing to up to 150 nm in diameter. Comparisons are made between exposures of warm rolled Plansee tungsten discs and ALMT ITER grade tungsten samples. Work supported by US DOE Contract DE-AC04-94AL85000 and the PSI Science Center.

78 FR 27975 - Center for Scientific Review Notice of Closed Meetings

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-13

... Scientific Review Special Emphasis Panel; Systemic Injury By Environmental Exposure. Date: June 11, 2013... . Name of Committee: Center for Scientific Review Special Emphasis Panel; Member conflict: Lung Diseases...

Electronic cigarettes are a source of thirdhand exposure to nicotine.

PubMed

Goniewicz, Maciej L; Lee, Lily

2015-02-01

Substances remaining on the surfaces in areas where people have smoked contribute to thirdhand exposure. Nicotine from tobacco smoke has been shown to react with oxidizing chemicals in the air to form secondary pollutants, such as carcinogenic nitrosamines. While previous studies have demonstrated thirdhand exposure to nicotine from tobacco smoke, none have investigated whether nicotine from electronic cigarettes (e-cigarettes) can also be deposited on various surfaces. Three brands of e-cigarettes were refilled with varying nicotine concentrations. We released 100 puffs from each product directly into an exposure chamber. Surface wipe samples were taken from 5 indoor 100 cm(2) surfaces (window, walls, floor, wood, and metal) pre- and post-release of vapors. Nicotine was extracted from the wipes and was analyzed using gas chromatography. Three of the 4 experiments showed significant increases in the amount of nicotine on all five surfaces. The floor and glass windows had the greatest increases in nicotine, on average by a factor of 47 and 6, respectively (p < .05). The average amount of nicotine deposited on a floor during each experiment was 205 μg/m(2) and varied from limit of quantitation to 550 μg/m(2). This study indicates that there is a risk for thirdhand exposure to nicotine from e-cigarettes. Thirdhand exposure levels differ depending on the surface and the e-cigarette brand. Future research should explore the potential risks of thirdhand exposure to carcinogens formed from the nicotine that is released from e-cigarettes. © The Author 2014. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Primordial clays on Mars formed beneath a steam or supercritical atmosphere.

PubMed

Cannon, Kevin M; Parman, Stephen W; Mustard, John F

2017-12-06

On Mars, clay minerals are widespread in terrains that date back to the Noachian period (4.1 billion to 3.7 billion years ago). It is thought that the Martian basaltic crust reacted with liquid water during this time to form hydrated clay minerals. Here we propose, however, that a substantial proportion of these clays was formed when Mars' primary crust reacted with a dense steam or supercritical atmosphere of water and carbon dioxide that was outgassed during magma ocean cooling. We present experimental evidence that shows rapid clay formation under conditions that would have been present at the base of such an atmosphere and also deeper in the porous crust. Furthermore, we explore the fate of a primordial clay-rich layer with the help of a parameterized crustal evolution model; we find that the primordial clay is locally disrupted by impacts and buried by impact-ejected material and by erupted volcanic material, but that it survives as a mostly coherent layer at depth, with limited surface exposures. These exposures are similar to those observed in remotely sensed orbital data from Mars. Our results can explain the present distribution of many clays on Mars, and the anomalously low density of the Martian crust in comparison with expectations.

Primordial clays on Mars formed beneath a steam or supercritical atmosphere

NASA Astrophysics Data System (ADS)

Cannon, Kevin M.; Parman, Stephen W.; Mustard, John F.

2017-12-01

On Mars, clay minerals are widespread in terrains that date back to the Noachian period (4.1 billion to 3.7 billion years ago). It is thought that the Martian basaltic crust reacted with liquid water during this time to form hydrated clay minerals. Here we propose, however, that a substantial proportion of these clays was formed when Mars’ primary crust reacted with a dense steam or supercritical atmosphere of water and carbon dioxide that was outgassed during magma ocean cooling. We present experimental evidence that shows rapid clay formation under conditions that would have been present at the base of such an atmosphere and also deeper in the porous crust. Furthermore, we explore the fate of a primordial clay-rich layer with the help of a parameterized crustal evolution model; we find that the primordial clay is locally disrupted by impacts and buried by impact-ejected material and by erupted volcanic material, but that it survives as a mostly coherent layer at depth, with limited surface exposures. These exposures are similar to those observed in remotely sensed orbital data from Mars. Our results can explain the present distribution of many clays on Mars, and the anomalously low density of the Martian crust in comparison with expectations.

Surface morphology changes to tungsten under exposure to He ions from an electron cyclotron resonance plasma source

NASA Astrophysics Data System (ADS)

Donovan, David; Maan, Anurag; Duran, Jonah; Buchenauer, Dean; Whaley, Josh

2015-11-01

Exposure of tungsten to low energy (<100 eV) helium plasmas at temperatures between 900-1900 K in both laboratory experiments and tokamaks has been shown to cause severe nanoscale modification of the near surface resulting the growth of tungsten tendrils. We used a relatively low flux (2.5x1019 ions m-2 s-1) compact ECR plasma source at Sandia-California to investigate the early stages of helium induced tungsten damage. Exposures of polished tungsten discs were performed and characterized using SEM, AFM, and FIB cross section imaging. Bubbles have been seen on the exposed tungsten surface and in sub-surface cross sections growing to up to 150 nm in diameter. Comparisons were made between exposures of warm rolled Plansee tungsten discs and ALMT ITER grade tungsten samples. A similar He plasma exposure stage has now been developed at the University of Tennessee-Knoxville with an improved compact ECR plasma source. Status of the new UTK exposure stage will be discussed as well as planned experiments and new material characterization techniques (EBSD, GIXRD). Work supported by US DOE Contract DE-AC04-94AL85000 and the PSI Science Center.

Present-day Exposures of Water Ice in the Northern Mid-latitudes of Mars

NASA Technical Reports Server (NTRS)

Allen, Carlton C.; Kanner, Lisa C.

2007-01-01

Water ice is exposed in the martian north polar cap, but is rarely exposed beyond the cap boundary. Orbital gamma ray spectrometry data strongly imply the presence of water ice within meters of the surface at latitudes north of approximately 60deg. We have examined mid-latitude areas of the northern plains displaying residual ice-rich layers, and report evidence of present-day surface exposures of water ice. These exposures, if confirmed, could con-strain the latitudinal and temporal stability of surface ice on Mars.

Comment on Gribenski, N. et al., 2016. Complex patterns of glacier advances during the late glacial in the Chagan Uzun Valley, Russian Altai. Quaternary Science Reviews 149, 288-305

NASA Astrophysics Data System (ADS)

Herget, Jürgen; Carling, Paul; Agatova, Anna; Batbaatar, Jigjidsurengiin; Borodavko, Pavel; Gillespie, Alan; Nepop, Roman

2017-07-01

Gribenski et al. (2016) investigated moraines of the Chagan-Uzun valley in the Russian Altai mountains, concluding from 18 cosmic-ray exposure ages that they slightly predated ∼19 ka, within MIS 2. The moraines extended below the highest stand of the Kuray/Chuja palaeolakes that gave rise to outburst floods down Chuja River. Gribenski et al. (2016) suggested that the ages from their lowest dated moraine may be minima due to shielding from cosmic-ray exposure by the lake waters for a few thousand years. They noted that their dating agrees with data from other palaeoglaciers in the region and throughout the Northern Hemisphere, and shows that the regional Last Glacial Maximum (LGM) in the Altai occurred during MIS 2.

Irreversible adsorption of atmospheric helium on olivine: A lobster pot analogy

NASA Astrophysics Data System (ADS)

Protin, Marie; Blard, Pierre-Henri; Marrocchi, Yves; Mathon, François

2016-04-01

This study reports new experimental results that demonstrate that large amounts of atmospheric helium may be adsorbed onto the surfaces of olivine grains. This behavior is surface-area-related in that this contamination preferentially affects grains that are smaller than 125 μm in size. One of the most striking results of our study is that in vacuo heating at 900 °C for 15 min is not sufficient to completely remove the atmospheric contamination. This suggests that the adsorption of helium may involve high-energy trapping of helium through irreversible anomalous adsorption. This trapping process of helium can thus be compared to a ;lobster pot; adsorption: atmospheric helium easily gets in, but hardly gets out. While this type of behavior has previously been reported for heavy noble gases (Ar, Kr, Xe), this is the first time that it has been observed for helium. Adsorption of helium has, until now, generally been considered to be negligible on silicate surfaces. Our findings have significant implications for helium and noble gas analysis of natural silicate samples, such as for cosmic-ray exposure dating or noble gas characterization of extraterrestrial material. Analytical procedures in future studies should be adapted in order to avoid this contamination. The results of this study also allow us to propose an alternative explanation for previously described matrix loss of cosmogenic 3He.

Landforms, sediments and dates to constrain rates and style of marine-influenced ice sheet decay; the BRITICE-CHRONO project.

NASA Astrophysics Data System (ADS)

Clark, Chris

2014-05-01

Uncertainty exists regarding the future mass of the Antarctic and Greenland ice sheets and how they will respond to forcings from sea level, and atmospheric and ocean temperatures. If we want to know more about the mechanisms and rate of change of shrinking ice sheets, then why not examine an ice sheet that has fully disappeared and track its retreat through time? If achieved in enough detail such information on ice retreat could be a data-rich playground for improving the next breed of numerical ice sheet models to be used in ice and sea level forecasting. We regard that the last British-Irish Ice Sheet is a good target for this work, on account of its small size, density of information and with its numerous researchers already investigating it. Geomorphological mapping across the British Isles and the surrounding continental shelf has revealed the nature and distribution of glacial landforms. Here we demonstrate how such data have been used to build a pattern of ice margin retreat. The BRITICE-CHRONO consortium of Quaternary scientists and glaciologists, are now working on a project running from 2012 - 2017 to produce an ice sheet wide database of geochronometric dates to constrain and then understand ice margin retreat. This is being achieved by focusing on 8 transects running from the continental shelf edge to a short distance (10s km) onshore and acquiring marine and terrestrial samples for geochronometric dating. The project includes funding for 587 radiocarbon, 140 OSL and 158 TCN samples for surface exposure dating; with sampling accomplished by two research cruises and 16 fieldwork campaigns. Results will reveal the timing and rate of change of ice margin recession for each transect, and combined with existing landform and dating databases, will be used to build an ice sheet-wide empirical reconstruction of retreat. Simulations using two numerical ice sheet models, fitted against the margin data, will help us understand the nature and significance of sea-level rise and ocean/atmosphere forcing on influencing the rate of retreat and ice sheet demise and the effect that bed topography has in controlling this.

Smoothing Polymer Surfaces by Solvent-Vapor Exposure

NASA Astrophysics Data System (ADS)

Anthamatten, Mitchell

2003-03-01

Ultra-smooth polymer surfaces are of great importance in a large body of technical applications such as optical coatings, supermirrors, waveguides, paints, and fusion targets. We are investigating a simple approach to controlling surface roughness: by temporarily swelling the polymer with solvent molecules. As the solvent penetrates into the polymer, its viscosity is lowered, and surface tension forces drive surface flattening. To investigate sorption kinetics and surface-smoothing phenomena, a series of vapor-deposited poly(amic acid) films were exposed to dimethyl sulfoxide vapors. During solvent exposure, the surface topology was continuously monitored using light interference microscopy. The resulting power spectra indicate that high-frequency defects smooth faster than low-frequency defects. This frequency dependence was studied by depositing polymer films onto a series of 2D sinusoidal surfaces and performing smoothing experiments. Results show that the amplitudes of the sinusoidal surfaces decay exponentially with solvent exposure time, and the exponential decay constants are proportional to surface frequency. This work was performed under the auspices of the U.S. Department of Energy by the University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

Evaluation of selected sidewalk pavement surfaces for vibration experienced by users of manual and powered wheelchairs.

PubMed

Cooper, Rory A; Wolf, Erik; Fitzgerald, Shirley G; Kellerher, Annmarie; Ammer, William; Boninger, Michael L; Cooper, Rosemarie

2004-01-01

Obstacles such as bumps, curb descents, and uneven driving surfaces cause vibrations that affect the wheelchair, and in turn, the wheelchair user. Chronic exposure can cause low-back pain, disk degeneration, and other harmful effects. Little research has been conducted to assess the vibrations experienced by wheelchair users. The purpose of this study was to conduct an evaluation of the vibration exposure during electric-powered wheelchair driving and mechanical energy requirements for manual wheelchair propulsion over selected sidewalk surfaces. The goal was to determine the criteria for a wheelchair-pedestrian access route that does not require excessive propulsive work or expose wheelchair users to potentially harmful vibrations. Ten unimpaired individuals participated in this study. Six sidewalk surfaces were tested. Measured variables included power of the acceleration per octave, mechanical work to propel over surfaces, peak acceleration, and frequency at which peak acceleration occurs. For both the manual and electric-powered wheelchair, at 1 m/s, significant differences were found in peak accelerations between the seat and footrest (P < 0.0001) and between the sidewalk surfaces (P = 0.004). The greatest risk for injury caused by shock and vibration exposure occurs at frequencies near the natural frequency of seated humans (4-15 Hz). The values for work required to propel over the surfaces tested were not statistically significantly different. Besides appearance and construction, the only distinguishing characteristic was surface roughness caused by the joints. When treating the poured concrete sidewalk as the standard, surfaces 2, 3, 5, and 6 compared most favorably in terms of vibration exposure, whereas surface 4 produced mixed results. Surfaces 2, 3, 5, and 6 yielded results that were similar to the poured concrete sidewalk and could be considered acceptable for wheelchair users. In conclusion, surfaces other than the traditional poured concrete can be used for pedestrian access routes without adding vibration exposure or reducing propulsion efficiency.

Modification of W surfaces by exposure to hollow cathode plasmas

NASA Astrophysics Data System (ADS)

Stancu, C.; Stokker-Cheregi, F.; Moldovan, A.; Dinescu, M.; Grisolia, C.; Dinescu, G.

2017-10-01

In this work, we assess the surface modifications induced on W samples following exposure to He and He/H2 radiofrequency plasmas in hollow cathode discharge configuration. Our study addresses issues that relate to the use of W in next-generation fusion reactors and, therefore, the investigation of W surface degradation following exposure and heating by plasmas to temperatures above 1000 °C is of practical importance. For these experiments, we used commercially available tungsten samples having areas of 30 × 15 mm and 0.1 mm thickness. The hollow cathode plasma was produced using a radiofrequency (RF) generator (13.56 MHz) between parallel plate electrodes. The W samples were mounted as one of the electrodes. The He and He/H2 plasma discharges had a combined effect of heating and bombardment of the W surfaces. The surface modifications were studied for discharge powers between 200 and 300 W, which resulted in the heating of the samples to temperatures between 950 and 1230 °C, respectively. The samples were weighed prior and after plasma exposure, and loss of mass was measured following plasma exposure times up to 90 min. The analysis of changes in surface morphology was carried out by optical microscopy, scanning electron microscopy and atomic force microscopy. Additionally, optical emission spectra of the respective plasmas were recorded from the region localized inside the hollow cathode gap. We discuss the influence of experimental parameters on the changes in surface morphology.

Process for producing cadmium sulfide on a cadmium telluride surface

DOEpatents

Levi, Dean H.; Nelson, Art J.; Ahrenkiel, Richard K.

1996-01-01

A process for producing a layer of cadmium sulfide on a cadmium telluride surface to be employed in a photovoltaic device. The process comprises providing a cadmium telluride surface which is exposed to a hydrogen sulfide plasma at an exposure flow rate, an exposure time and an exposure temperature sufficient to permit reaction between the hydrogen sulfide and cadmium telluride to thereby form a cadmium sulfide layer on the cadmium telluride surface and accomplish passivation. In addition to passivation, a heterojunction at the interface of the cadmium sulfide and the cadmium telluride can be formed when the layer of cadmium sulfide formed on the cadmium telluride is of sufficient thickness.

Process for producing cadmium sulfide on a cadmium telluride surface

DOEpatents

Levi, D.H.; Nelson, A.J.; Ahrenkiel, R.K.

1996-07-30

A process is described for producing a layer of cadmium sulfide on a cadmium telluride surface to be employed in a photovoltaic device. The process comprises providing a cadmium telluride surface which is exposed to a hydrogen sulfide plasma at an exposure flow rate, an exposure time and an exposure temperature sufficient to permit reaction between the hydrogen sulfide and cadmium telluride to thereby form a cadmium sulfide layer on the cadmium telluride surface and accomplish passivation. In addition to passivation, a heterojunction at the interface of the cadmium sulfide and the cadmium telluride can be formed when the layer of cadmium sulfide formed on the cadmium telluride is of sufficient thickness. 12 figs.

Atomic Oxygen Textured Polymers

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Rutledge, Sharon K.; Hunt, Jason D.; Drobotij, Erin; Cales, Michael R.; Cantrell, Gidget

1995-01-01

Atomic oxygen can be used to microscopically alter the surface morphology of polymeric materials in space or in ground laboratory facilities. For polymeric materials whose sole oxidation products are volatile species, directed atomic oxygen reactions produce surfaces of microscopic cones. However, isotropic atomic oxygen exposure results in polymer surfaces covered with lower aspect ratio sharp-edged craters. Isotropic atomic oxygen plasma exposure of polymers typically causes a significant decrease in water contact angle as well as altered coefficient of static friction. Such surface alterations may be of benefit for industrial and biomedical applications. The results of atomic oxygen plasma exposure of thirty-three (33) different polymers are presented, including typical morphology changes, effects on water contact angle, and coefficient of static friction.

75 FR 54421 - Sixth Meeting: RTCA Special Committee 223: Airport Surface Wireless Communications

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-07

... 223: Airport Surface Wireless Communications AGENCY: Federal Aviation Administration (FAA), Department of Transportation (DOT). ACTION: Notice of RTCA Special Committee 223: Airport Surface Wireless... Committee 223: Airport Surface Wireless Communications. DATES: The meeting will be held September 28-30...

Experimental animal studies of radon and cigarette smoke

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

Cross, F.T.; Dagle, G.E.; Gies, R.A.

Cigarette-smoking is a dominant cause of lung cancer and confounds risk assessment of exposure to radon decay products. Evidence in humans on the interaction between cigarette-smoking and exposure to radon decay products, although limited, indicates a possible synergy. Experimental animal data, in addition to showing synergy, also show a decrease or no change in risk with added cigarette-smoke exposures. This article reviews previous animal data developed at Compagnie Generale des Matieres Nucleaires and Pacific Northwest Laboratory (PNL) on mixed exposures to radon and cigarette smoke, and highlights new initiation-promotion-initiation (IPI) studies at PNL that were designed within the framework ofmore » a two-mutation carcinogenesis model. Also presented are the PNL exposure system, experimental protocols, dosimetry, and biological data observed to date in IPI animals.« less

The age of the meteorite recovery surfaces of Roosevelt County, New Mexico, USA

NASA Technical Reports Server (NTRS)

Zolensky, Michael E.; Rendell, Helen M.; Wilson, Ivan; Wells, Gordon L.

1992-01-01

We have obtained minimum age estimates for the sand units underlying the two largest meteorite deflation surfaces in Roosevelt County, New Mexico, USA, using thermoluminescence dating techniques. The dates obtained ranged from 53.5 (+/- 5.4) to 95.2 (+/- 9.5) ka, and must be considered lower limits for the terrestrial ages of the meteorites found within these specific deflation surfaces. These ages greatly exceed previous measurements from adjacent meteorite-producing deflation basins. We find that Roosevelt County meteorites are probably terrestrial contemporaries of the meteorites found at most accumulation zones in Antarctica. The apparent high meteorite accumulation rate reported for Roosevelt County by Zolensky et al. (1990) is incorrect, as it used an age of 16 ka for all Roosevelt County recovery surfaces. We conclude that the extreme variability of terrestrial ages of the Roosevelt County deflation surfaces effectively precludes their use for calculations of the meteorite accumulation rate at the Earth's surface.

Dating young geomorphic surfaces using age of colonizing Douglas fir in southwestern Washington and northwestern Oregon, USA

USGS Publications Warehouse

Pierson, T.C.

2007-01-01

Dating of dynamic, young (<500 years) geomorphic landforms, particularly volcanofluvial features, requires higher precision than is possible with radiocarbon dating. Minimum ages of recently created landforms have long been obtained from tree-ring ages of the oldest trees growing on new surfaces. But to estimate the year of landform creation requires that two time corrections be added to tree ages obtained from increment cores: (1) the time interval between stabilization of the new landform surface and germination of the sampled trees (germination lag time or GLT); and (2) the interval between seedling germination and growth to sampling height, if the trees are not cored at ground level. The sum of these two time intervals is the colonization time gap (CTG). Such time corrections have been needed for more precise dating of terraces and floodplains in lowland river valleys in the Cascade Range, where significant eruption-induced lateral shifting and vertical aggradation of channels can occur over years to decades, and where timing of such geomorphic changes can be critical to emergency planning. Earliest colonizing Douglas fir (Pseudotsuga menziesii) were sampled for tree-ring dating at eight sites on lowland (<750 m a.s.l.), recently formed surfaces of known age near three Cascade volcanoes - Mount Rainier, Mount St. Helens and Mount Hood - in southwestern Washington and northwestern Oregon. Increment cores or stem sections were taken at breast height and, where possible, at ground level from the largest, oldest-looking trees at each study site. At least ten trees were sampled at each site unless the total of early colonizers was less. Results indicate that a correction of four years should be used for GLT and 10 years for CTG if the single largest (and presumed oldest) Douglas fir growing on a surface of unknown age is sampled. This approach would have a potential error of up to 20 years. Error can be reduced by sampling the five largest Douglas fir instead of the single largest. A GLT correction of 5 years should be added to the mean ring-count age of the five largest trees growing on the surface being dated, if the trees are cored at ground level. This correction would have an approximate error of ??5 years. If the trees are cored at about 1.4 m above the round surface (breast height), a CTG correction of 11 years should be added to the mean age of the five sampled trees (with an error of about ??7 years).

Toward Developing a New Occupational Exposure Metric Approach for Characterization of Diesel Aerosols

PubMed Central

Cauda, Emanuele G.; Ku, Bon Ki; Miller, Arthur L.; Barone, Teresa L.

2015-01-01

The extensive use of diesel-powered equipment in mines makes the exposure to diesel aerosols a serious occupational issue. The exposure metric currently used in U.S. underground noncoal mines is based on the measurement of total carbon (TC) and elemental carbon (EC) mass concentration in the air. Recent toxicological evidence suggests that the measurement of mass concentration is not sufficient to correlate ultrafine aerosol exposure with health effects. This urges the evaluation of alternative measurements. In this study, the current exposure metric and two additional metrics, the surface area and the total number concentration, were evaluated by conducting simultaneous measurements of diesel ultrafine aerosols in a laboratory setting. The results showed that the surface area and total number concentration of the particles per unit of mass varied substantially with the engine operating condition. The specific surface area (SSA) and specific number concentration (SNC) normalized with TC varied two and five times, respectively. This implies that miners, whose exposure is measured only as TC, might be exposed to an unknown variable number concentration of diesel particles and commensurate particle surface area. Taken separately, mass, surface area, and number concentration did not completely characterize the aerosols. A comprehensive assessment of diesel aerosol exposure should include all of these elements, but the use of laboratory instruments in underground mines is generally impracticable. The article proposes a new approach to solve this problem. Using SSA and SNC calculated from field-type measurements, the evaluation of additional physical properties can be obtained by using the proposed approach. PMID:26361400

Review and Design of Low-Dose Bacillus anthracis Inhalation ...

EPA Pesticide Factsheets

Report In July 2011, EPA NHSRC sponsored a Review and Design of Low-Dose Bacillus anthracis Inhalation Exposures meeting to review the research done to date and to identify gaps that future research should address regarding low-dose exposures. This effort brought together many organizations across the country, including EPA’s program offices, federal government agencies and laboratories, academia, and the private sector. Participants of the conference shared knowledge, explored differing opinions, and expanded understanding of the current state of research for low-dose exposure and future research needs. This report represents a summary of the presentations and discussions during the meeting.

Impairment of the Bacterial Biofilm Stability by Triclosan

PubMed Central

Hubas, Cédric; Behrens, Sebastian; Ricciardi, Francesco; Paterson, David M.

2012-01-01

The accumulation of the widely-used antibacterial and antifungal compound triclosan (TCS) in freshwaters raises concerns about the impact of this harmful chemical on the biofilms that are the dominant life style of microorganisms in aquatic systems. However, investigations to-date rarely go beyond effects at the cellular, physiological or morphological level. The present paper focuses on bacterial biofilms addressing the possible chemical impairment of their functionality, while also examining their substratum stabilization potential as one example of an important ecosystem service. The development of a bacterial assemblage of natural composition – isolated from sediments of the Eden Estuary (Scotland, UK) – on non-cohesive glass beads (<63 µm) and exposed to a range of triclosan concentrations (control, 2 – 100 µg L−1) was monitored over time by Magnetic Particle Induction (MagPI). In parallel, bacterial cell numbers, division rate, community composition (DGGE) and EPS (extracellular polymeric substances: carbohydrates and proteins) secretion were determined. While the triclosan exposure did not prevent bacterial settlement, biofilm development was increasingly inhibited by increasing TCS levels. The surface binding capacity (MagPI) of the assemblages was positively correlated to the microbial secreted EPS matrix. The EPS concentrations and composition (quantity and quality) were closely linked to bacterial growth, which was affected by enhanced TCS exposure. Furthermore, TCS induced significant changes in bacterial community composition as well as a significant decrease in bacterial diversity. The impairment of the stabilization potential of bacterial biofilm under even low, environmentally relevant TCS levels is of concern since the resistance of sediments to erosive forces has large implications for the dynamics of sediments and associated pollutant dispersal. In addition, the surface adhesive capacity of the biofilm acts as a sensitive measure of ecosystem effects. PMID:22523534

­Chronology of the Last Termination of Tsagaan Gol-Potanin Glacier Valley, Altai Mountains, Mongolia using 10Be surface-exposure dating

NASA Astrophysics Data System (ADS)

Radue, M. J.; Putnam, A. E.; Strand, P.; Norris, N. R.

2017-12-01

The last termination ( 19-11 ka) marks the end of the last ice age and the transition to modern interglacial conditions. Increasing Northern Hemisphere summer insolation alone cannot account for the rapid global warming during the termination and the mechanisms that triggered the dramatic deglaciation are unresolved. Various hypotheses for deglacial warming include an increase in atmospheric CO­2, changes in ocean circulation, shifting wind belts, and water vapor. Here, we investigate the last termination in the Mongolian Altai (49°N, 88°E), a mountain range in the heart of Asia, to constrain the nature of the termination in the center of Earth's largest continent. We present a 10Be surface-exposure chronology for a system of glacial landforms in the Tsagaan Gol- Potanin Glacier Valley. Our chronology is underpinned by detailed glacial geomorphic maps made using satellite and unmanned aerial vehicle (UAV) imagery. Based on our glacial reconstruction, we estimate changes in atmospheric temperature from the Last Glacial Maximum to the Late Holocene using snowline reconstruction techniques. Mongolia is an ideal location to document past climate because it is isolated from oceanic influences; therefore, our record should provide insight into the roles of local radiation forcing from changes in Earth's orbital configuration, greenhouse gases, and atmospheric heat transfer in Asian climate dynamics. With a high-resolution chronology and detailed glacial geomorphic maps of the Potanin-Tsagaan Gol Valley in the Mongolian Altai, we compare the timing of deglaciation in interior Asia with records of climate drivers, such as CO­2­­, to understand what caused this major global warming event.

Morphometric analysis of abdominal organs and rib cage: Implication for risk of solid organ injuries in children.

PubMed

Harbaugh, Calista M; Shlykov, Maksim A; Tsuchida, Ryan E; Holcombe, Sven A; Hirschl, Jake; Wang, Stewart C; Ehrlich, Peter F

2015-06-01

Motor vehicle crashes are the leading cause of injury-related mortality in children, with a higher rate of multiorgan injuries than in adults. This may be related to increased solid organ volume relative to abdominal cavity and decreased protection of an underdeveloped cartilaginous rib cage in young children. To date, these anatomic relationships have not been fully described. Our study used analytic morphomics to obtain precise measures of the pediatric liver, spleen, kidneys, and ribs. This pilot study included 215 trauma patients (aged 0-18 years) with anonymized computed tomography (CT) scans. Liver, spleen, and kidney volumes were modeled using semiautomatic algorithms (MATLAB 2013a, MathWorks Inc., Natick, MA). Thirty-one scans were adequate to model the rib cage. Pearson's r was used to correlate absolute organ volume, fractional organ volume, and organ exposure with age and weight. Spleen, right and left kidney, and liver volumes increased with age and weight (p < 0.01). Right/left kidney and liver fractional volumes decreased with age (p < 0.01), whereas spleen fractional volume remained relatively constant. Exposed surface area of the liver only significantly decreased with age in the anterior (p < 0.01), right (p < 0.01), and posterior views (p = 0.02). With this study, we have demonstrated the ability to model solid organ and rib cage anatomy of children using cross-sectional imaging. In younger children, there may be a decrease in fractional organ volume and increase in liver surface exposure, although analysis of a larger sample size is warranted. In the future, this information may be used to improve the design of safety restraints in motor vehicles.

Dating Informed Correlations and Large Earthquake Recurrence at the Hokuri Creek Paleoseismic Site, Alpine Fault, South Island, New Zealand

NASA Astrophysics Data System (ADS)

Biasi, G. P.; Clark, K.; Berryman, K. R.; Cochran, U. A.; Prior, C.

2010-12-01

The Hokuri Creek paleoseismic site on the Alpine fault in south Westland, New Zealand has yielded a remarkable history of fault activity spanning the past ~7000 years. Evidence for earthquake occurrence and timing has been developed primarily from natural exposures created after a geologically major incision event a few hundred years ago. Prior to this event, the elevation of the spillway of Hokuri Creek into its previous drainage was controlled by NE translation of a shutter ridge during earthquakes. Each event increased the base level for sediment accumulation upstream by decimetres to perhaps a metre. Each increase in base level is associated with a period of accumulation principally of clean fine silts and rock flour. With infilling and time, the wetlands reestablish and sedimentation transitions to a slower and more organic-rich phase (Clark et al., this meeting). At least 18 such cycles have been identified at the site. Carbonaceous material is abundant in almost all layers. Much of the dating is done on macrofossils - individual beech tree leaves, reeds, and similar fragile features. Reworking is considered unlikely due to the fragility of the samples. All dates were developed by the Rafter Radiocarbon Laboratory of the National Isotope Centre at GNS. Delta 13C was measured and used to correct for fractionation. Dating earthquakes at the Hokuri Creek site presents some special challenges. Individual stratigraphic sections around the site expose different time intervals. The Main Section series provides the most complete single section, with over 5000 years of represented. Nearby auxiliary exposures cover nearly 1500 years more. Date series from individual exposures tend to be internally very consistent with stratigraphic ordering, but by virtue of their spatial separation, correlations between sections are more difficult. We find, however, that the distinctive layering and the typical 2-4 centuries between primary silt layers provides a way to cross-correlate sections at the site. Within a series of dates from a section, ordering with intrinsic precision of the dates indicates an uncertainty at event horizons on the order of 50 years, while the transitions from peat to silt indicating an earthquake are separated by several times this amount. The effect is to create a stair-stepping date sequence that often allows us to link sections and improve dating resolution in both sections. The combined section provides clear evidence for at least 18 earthquake-induced cycles. Event recurrence would be about 390 years in a simple average. Internal evidence and close examination of date sequences provide preliminary indications of as many as 22 earthquakes could be represented at Hokuri Creek, and a recurrence interval of ~320 years. Both sequences indicate a middle sequence from 3800 to 1000 BC in which recurrence intervals are resolvably longer than average. Variability in recurrence is relatively small - relatively few intervals are even >1.5x the average. This indicates that large earthquakes on the Alpine Fault of South Island, New Zealand are best fit by a time-predictable model.

76 FR 6179 - Eighth Meeting: RTCA Special Committee 223: Airport Surface Wireless Communications

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-03

... Committee 223: Airport Surface Wireless Communications AGENCY: Federal Aviation Administration (FAA), Department of Transportation (DOT). ACTION: Notice of RTCA Special Committee 223: Airport Surface Wireless... Committee 223: Airport Surface Wireless Communications. DATES: The meeting will be held February 22-23, 2011...

75 FR 66423 - Seventh Meeting: RTCA Special Committee 223: Airport Surface Wireless Communications

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-28

... Committee 223: Airport Surface Wireless Communications AGENCY: Federal Aviation Administration (FAA), Department of Transportation (DOT). ACTION: Notice of RTCA Special Committee 223: Airport Surface Wireless... Committee 223: Airport Surface Wireless Communications. DATES: The meeting will be held November 16-17, 2010...

78 FR 33145 - Meeting: RTCA Special Committee 223, Airport Surface Wireless Communications

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-03

..., Airport Surface Wireless Communications AGENCY: Federal Aviation Administration (FAA), U.S. Department of Transportation (DOT). ACTION: Meeting Notice of RTCA Special Committee 223, Airport Surface Wireless... Committee 223, Airport Surface Wireless Communications. DATES: The meeting will be held June 26-28, 2013...

Elemental geochemistry and strontium-isotope stratigraphy of Cenomanian to Santonian neritic carbonates in the Zagros Basin, Iran

NASA Astrophysics Data System (ADS)

Navidtalab, Amin; Rahimpour-Bonab, Hossain; Huck, Stefan; Heimhofer, Ulrich

2016-12-01

A Neo-Tethyan upper Cenomanian-Santonian neritic carbonate ramp succession (Sarvak and Ilam formations), drilled in the Zagros Basin in southwest Iran, was investigated via detailed sedimentology, microfacies analysis, elemental geochemistry and Sr-isotope stratigraphy (SIS). The succession contains two exposure surfaces, which are known as the CT-ES and mT-ES (Cenomanian-Turonian and middle Turonian, respectively), and associated prominent negative carbon-isotope excursions that represent important regional stratigraphic marker horizons. Precise knowledge about the onset of platform exposure and the duration of the exposure-related hiatus, however, is currently lacking due to a rather low-resolved shallow-water biostratigraphic framework and a bulk carbonate carbon-isotope pattern that clearly differs from global Late Cretaceous reference curves. Therefore, the existing bio-chemostratigraphic framework was complemented by bulk carbonate strontium-isotope stratigraphy (SIS). As bulk carbonate material is in particular prone to diagenetic alteration, a careful selection of least altered samples has been carried out by means of elemental geochemistry and petrography. In contrast to what could be expected, the meteoric alteration of limestones beneath both exposure surfaces is not clearly expressed by increasing iron and manganese and coeval decreasing strontium contents. On the contrary, the impact of meteoric diagenesis is well illustrated via pronounced increases in Rb concentrations and concomitant prominent positive shifts to radiogenic strontium-isotope values, an observation that clearly reflects the decay of continentally derived 87Rb into 87Sr. Rubidium corrected strontium-isotope values place the CT-ES around the Cenomanian-Turonian boundary and point to an exposure duration of less than 0.4 Myr. This rather short-term CT-ES related hiatus is supported by petrographic evidence, which indicates a youth karstification stage of strata beneath the CT-ES. Following SIS, the Ilam-Sarvak transition at the top of Nezzazatinella-Dicyclina interval zone coincides with the mT-ES. Carbonates placing above this transition (Ilam Formation) are ascribed to the earliest to latest early Santonian, while carbonates immediately beneath the mT-ES (Sarvak Formation) are dated as late Turonian. SIS thus indicates a long-lasting hiatus of 4.5 Myr associated with the mT-ES. Emergence represented by the CT-ES is here proposed as harbinger of the mT-ES in the Zagros Basin, which most likely resulted from stepwise peripheral bulging due to ophiolite obduction in combination with a small-scale global sea level fall around 94 Ma.

Deglacial History of the Ecuadorian Andes and Implication for Climate Variations: Preliminary Results

NASA Astrophysics Data System (ADS)

Hall, M.; Rinterknecht, V. R.; Schaefer, J. M.; Seager, R.; Greene, A.

2004-12-01

Paleoclimate reconstructions are essential for evaluating the future evolution of natural climate variability and for determining climate sensitivity to external forcing. Reconstructing climate conditions from the Last Glacial Maximum (LGM) to the Holocene represents a unique opportunity to understand climate variability from full glacial conditions to modern warm conditions. The primary goal of our project, is to verify if the changes in temperature and precipitation driving the glacier event in the tropics during the well-documented Little Ice Age (LIA), may also account for the glaciations related to the LGM and the late glacial period. This inter-disciplinary project brings together specialists in glacial geology, surface exposure dating, and climate modeling. Our first trip to Ecuador took us to the Papallacta Valley at the rim of the Potrerillos Plateau. We developed detailed maps of the snowline lowering in the valley and took samples in well-exposed sections for radiocarbon dating. We used our maps and the age constraints on the deglacial history of the Papallacta Valley to estimate the possible combinations of changes in climate parameters related to reconstructed snowline variations. This local study represents the first step in a broader project that will cover most of the Ecuadorian Andes. We will also provide direct dating (3He, 10Be, and 36Cl) of the moraine sequences deposited during the retreat of the glaciers during the late Pleistocene. By the time of the project completion we want to evaluate the nature of the driving forces underlying the LGM and the late glacial event in view of the relatively well understood mechanisms behind the termination of the LIA, and we want to compare the produced data to mid- and high- latitude areas in order to evaluate the regional footprint of dimension and timing of glacier response to climate change.

Antimicrobial copper alloy surfaces are effective against vegetative but not sporulated cells of gram-positive Bacillus subtilis.

PubMed

San, Kaungmyat; Long, Janet; Michels, Corinne A; Gadura, Nidhi

2015-10-01

This study explores the role of membrane phospholipid peroxidation in the copper alloy mediated contact killing of Bacillus subtilis, a spore-forming gram-positive bacterial species. We found that B. subtilis endospores exhibited significant resistance to copper alloy surface killing but vegetative cells were highly sensitive to copper surface exposure. Cell death and lipid peroxidation occurred in B. subtilis upon copper alloy surface exposure. In a sporulation-defective strain carrying a deletion of almost the entire SpoIIA operon, lipid peroxidation directly correlated with cell death. Moreover, killing and lipid peroxidation initiated immediately and at a constant rate upon exposure to the copper surface without the delay observed previously in E. coli. These findings support the hypothesis that membrane lipid peroxidation is the initiating event causing copper surface induced cell death of B. subtilis vegetative cells. The findings suggest that the observed differences in the kinetics of copper-induced killing compared to E. coli result from differences in cell envelop structure. As demonstrated in E. coli, DNA degradation was shown to be a secondary effect of copper exposure in a B. subtilis sporulation-defective strain. © 2015 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Antimicrobial copper alloy surfaces are effective against vegetative but not sporulated cells of gram-positive Bacillus subtilis

PubMed Central

San, Kaungmyat; Long, Janet; Michels, Corinne A; Gadura, Nidhi

2015-01-01

This study explores the role of membrane phospholipid peroxidation in the copper alloy mediated contact killing of Bacillus subtilis, a spore-forming gram-positive bacterial species. We found that B. subtilis endospores exhibited significant resistance to copper alloy surface killing but vegetative cells were highly sensitive to copper surface exposure. Cell death and lipid peroxidation occurred in B. subtilis upon copper alloy surface exposure. In a sporulation-defective strain carrying a deletion of almost the entire SpoIIA operon, lipid peroxidation directly correlated with cell death. Moreover, killing and lipid peroxidation initiated immediately and at a constant rate upon exposure to the copper surface without the delay observed previously in E. coli. These findings support the hypothesis that membrane lipid peroxidation is the initiating event causing copper surface induced cell death of B. subtilis vegetative cells. The findings suggest that the observed differences in the kinetics of copper-induced killing compared to E. coli result from differences in cell envelop structure. As demonstrated in E. coli, DNA degradation was shown to be a secondary effect of copper exposure in a B. subtilis sporulation-defective strain. PMID:26185055

Landscape development in an hyperarid sandstone environment along the margins of the Dead Sea fault: Implications from dated rock falls

USGS Publications Warehouse

Matmon, A.; Shaked, Y.; Porat, N.; Enzel, Y.; Finkel, R.; Lifton, N.; Boaretto, E.; Agnon, A.

2005-01-01

In this study, we explored the spatial and temporal relations between boulders and their original in-situ locations on sandstone bedrock cliffs. This was accomplished by combining field observations with dating methods using cosmogenic isotopes (10Be and 14C) and optically stimulated luminescence (OSL). Our conclusions bear both on the landscape evolution and cliff retreat process in the hyperarid region of Timna and on the methodology of estimating exposure ages using cosmogenic isotopes. We recognize three discrete rock fall events, at 31 ka, 15 ka, and 4 ka. In this hyperarid region, the most plausible triggering mechanism for rock fall events is strong ground acceleration caused by earthquakes generated by the nearby Dead Sea fault (DSF). Our record, however, under represents the regional earthquake record implying that ongoing development of detachment cracks prior to the triggering event might be slower than the earthquake cycle. Cliff retreat rates calculated using the timing of rock fall events and estimated thickness of rock removed in each event range between 0.14 m ky-1 and 2 m ky-1. When only full cycles are considered, we derive a more realistic range of 0.4 m ky-1 to 0.7 m ky-1. These rates are an order of magnitude faster than the calculated rate of surface lowering in the area. We conclude that sandstone cliffs at Timna retreat through episodic rock fall events that preserve the sharp, imposing, landscape characteristic to this region and that ongoing weathering of the cliff faces is minor. A 10%-20% difference in the 10Be concentrations in samples from matching boulder and cliff faces that have identical exposure histories and are located only a few meters apart indicates that cosmogenic nuclide production rates are sensitive to shielding and vary spatially over short distances. However, uncertainties associated with age calculations yielded boulder and matching cliff face ages that are similar within 1 ??. The use of external constraints in the form of field relations and OSL dating helped to establish each pair's age. The agreement between calculated 14C and 10Be ages indicates that the accumulation of 10Be at depth by the capture of slow deep-penetrating muons was properly accounted for in the study. ?? 2005 Elsevier B.V. All rights reserved.

MEASURING DIETARY EXPOSURE OF YOUNG CHILDREN

EPA Science Inventory

Young children do not consume foods in a structured manner. Their foods contact surfaces (hands, floors, eating surfaces, etc.) that may be contaminated while they are eating them. Thus, dietary exposures of young children are difficult to accurately assess or measure. A recen...

ESTIMATING EXCESS DIETARY EXPOSURES OF YOUNG CHILDREN

EPA Science Inventory

Nine children in a daycare that routinely applied the pesticide, esfenvalerate, were studied to assess excess dietary exposures. Surface wipes, a standard food item of processed American cheese slice pressed on the surface and handled by the child, an accelerometer reading, and ...

INVESTIGATION OF TRANSFER OF FLUORESCENT TRACERS FROM SURFACES TO SKIN

EPA Science Inventory

Under the provisions of the Food Quality Protection Act (FQPA), aggregate exposure assessments must be conducted for pesticides proposed for registration. Many aspects of dermal exposure assessment remain poorly quantified. For purposes of assessing surface-to-skin transfers ...

Effect of Exposure on the Mechanical Properties of Gamma MET PX

NASA Technical Reports Server (NTRS)

Draper, S. L.; Lerch, B. A.; Locci, I. E.; Shazly, M.; Prakash, V.

2004-01-01

The effect of a service environment exposure on the mechanical properties of a high Nb content TiAl alloy, Gamma MET PX , was assessed. Gamma MET PX, like other TiAl alloys, experiences a reduction of ductility following high temperature exposure. Exposure in Ar, air, and high-purity oxygen all resulted in a loss of ductility with the ductility reduction increasing with oxygen content in the exposure atmosphere. Embrittling mechanisms, including bulk microstructural changes, moisture induced environmental embrittlement, and near surface effects were investigated. The embrittlement has been shown to be a near-surface effect, most likely due to the diffusion of oxygen into the alloy.

ESR dating pleistocene barnacles from BC and Maine: a new method for tracking sea level change.

PubMed

Blackwell, Bonnie A B; Gong, J J J; Skinner, Anne R; Blais-Stevens, Andrée; Nelson, Robert E; Blickstein, Joel I B

2010-02-01

Barnacles have never been successfully dated by electron spin resonance (ESR). Living mainly in the intertidal zone, barnacles die when sea level changes cause their permanent exposure. Thus, dating the barnacles dates past sea level changes. From this, we can measure apparent sea level changes that occur due to ocean volume changes, crustal isostasy, and tectonics. ESR can date aragonitic mollusc shells ranging in age from 5 ka to at least 500 ka. By modifying the standard ESR method for molluscs to chemically dissolve 20 microm from off the shells, six barnacle samples from Norridgewock, Maine, and Khyex River, British Columbia, were tested for suitability for ESR dating. Due to Mn2+ interference peaks, the four Maine barnacle samples were not datable by ESR. Two barnacles from BC, which lacked Mn2+ interference, yielded a mean ESR age of 15.1 +/- 1.0 ka. These ages agree well with 14C dates on the barnacles themselves and wood in the overlying glaciomarine sediment. Although stability tests to calculate the mean dating signal lifetime and more ESR calibration tests against other barnacles of known age are needed to ensure the method's accuracy, ESR can indeed date Balanus, and thus, sea level changes.

Photo-responsive surface topology in chiral nematic media

NASA Astrophysics Data System (ADS)

Liu, Danqing; Bastiaansen, Cees W. M.; Toonder, Jaap. M. J.; Broer, Dirk J.

2012-03-01

We report on the design and fabrication of 'smart surfaces' that exhibit dynamic changes in their surface topology in response to exposure to light. The principle is based on anisotropic geometric changes of a liquid crystal network upon a change of the molecular order parameter. The photomechanical property of the coating is induced by incorporating an azobenzene moiety into the liquid crystal network. The responsive surface topology consists of regions with two different types of molecular order: planar chiral-nematic areas and homeotropic. Under flood exposure with 365 nm light the surfaces deform from flat to one with a surface relief. The height of the relief structures is of the order of 1 um corresponding to strain difference of around 20%. Furthermore, we demonstrate surface reliefs can form either convex or concave structures upon exposure to UV light corresponding to the decrease or increase molecular order parameter, respectively, related to the isomeric state of the azobenzene crosslinker. The reversible deformation to the initial flat state occurs rapidly after removing the light source.

Present day and Allerod - Younger Dryas marine 14C reservoir ages of surface waters in the North Atlantic-Norwegian Sea

NASA Astrophysics Data System (ADS)

Mangerud, J.; Bondevik, S.; Gulliksen, S.; Birks, H. H.; Reimer, P.; Hufthammer, A. K.; Hoisaeter, T.

2005-12-01

In order to compare radiocarbon dates on marine and terrestrial samples, the former have to be corrected for a marine reservoir age. We have calculated present day reservoir ages in this area by dating 22 whales collected AD 1860-1901 and 23 molluscs collected AD 1857-1926. Whales feed on pelagic organisms and will provide the reservoir age for the open ocean surface water. However, they travel large distances and integrate the reservoir ages of water masses along their way. Molluscs are stationary and monitor the sea water passing their living site. For the surface water in the N-Atlantic and Norwegian Sea we recommend to use the mean obtained for the two sets, i.e. reservoir ages of 400 +/- 40 and 375 +/- 30 years relative to tree rings of Intcal04 and British oak respectively, for the parts of the Holocene where specific time-dependent reservoir ages are not determined. The reservoir ages relative to British oak best reflects regional processes and we therefore prefer those, whereas IntCal04 ages are much more precisely determined, but dominated by trees from NW-USA in this time period. The reservoir ages for Allerod-Younger Dryas (YD) are obtained by dating parallel samples of terrestrial plant fragments and marine shells from sediment cores from the outermost western coast of Norway. The marine mud contains both plant fragments blown or washed in from adjacent land and in situ marine shells. In the earliest period (13,800-14,500 cal yrs BP) the reservoir age is 300-400 years, similar to present day values. This suggests that the exchange of CO2 between the atmosphere and the surface ocean was comparable to the present. During a short interval 13,200-13,500 cal yrs BP we found higher reservoir ages of 500-600 years coinciding with lower organic carbon content in our cores, and an inter-Allerod fluctuation seen in marine records. During the early YD the reservoir ages increased gradually from 400 to 650 years, causing a 700-14C year-long plateau, centred at 11,000 14C yrs BP, for marine dates at a time of high resolution for terrestrial dates. This may reflect increased annual sea-ice cover, reducing the rate of CO2 exchange between the atmosphere and the sea surface. But better; our dates show that the marine 14C ages decreased rapidly from 10,600 to 10,100 14C yrs BP. This is the time of the well-known 10,000 14C year plateau in terrestrial dates, and the result is that one can obtain higher resolution of calibrated marine 14C dates at the YD/Holocene transition than for terrestrial 14C dates. This presentation is based on two manuscripts that will be submitted about 1. Sept 2005: Bondevik, S., Mangerud, J., Birks, H. H., Gulliksen, S., and Reimer, P.: Late-glacial reservoir ages of surface waters in the North Atlantic. Mangerud, J., Bondevik, S., Gulliksen, S., Hufthammer, A.K., Hoisaeter, T.: Marine 14C reservoir ages for whales and molluscs from the North Atlantic.

Hospital-Based Case-Control Study of MDS Subtypes and Benzene Exposure in Shanghai

PubMed Central

Copley, G. Bruce; Schnatter, A. Robert; Armstrong, Thomas W.; Irons, Richard D.; Chen, Min; Wang, Xiao Qin; Kerzic, Patrick

2017-01-01

Objective: Due to the sparse data on benzene exposure and myelodysplastic syndrome (MDS) subtypes, we studied this relationship in patients from 29 hospitals in Shanghai, China. Methods: We recruited 604 cases of MDS and 1193 controls matched on age, sex, and admission date. We interviewed subjects for information on workplace and lifestyle exposures, and developed semi-quantitative exposure estimates. Results: Benzene exposure showed a direct exposure–response pattern with refractory cytopenia with multilineage dysplasia, a less certain association with refractory cytopenia with unilineage dysplasia, and no association with other MDS subtypes. A different pattern was observed with farm residence and smoking, which was primarily related to refractory anemias. Conclusions: This research demonstrates the importance of MDS subtype specification for more robust etiologic insights. Our data suggests that subtypes with non-erythroid dysplasia are associated with benzene exposure. PMID:28146040

Impact-Induced Muscle Damage and Contact-Sport: Aetiology, Effects on Neuromuscular Function and Recovery, and the Modulating Effects of Adaptation and Recovery Strategies.

PubMed

Naughton, Mitchell; Miller, Joanna; Slater, Gary J

2017-11-28

Athletes involved in contact-sports are habitually exposed to skeletal muscle damage as part of their training and performance environments. This often leads to exercise-induced muscle damage (EIMD) resulting from repeated eccentric and/or high-intensity exercise, and impact-induced muscle damage (IIMD) resulting from collisions with opponents and the playing surface. Whilst EIMD has been an area of extensive investigation, IIMD has received comparatively little research, with the magnitude and timeframe of alterations following IIMD not presently well understood. It is currently thought that EIMD occurs through an overload of mechanical stress causing ultrastructural damage to the cellular membrane constituents. Damage leads to compromised ability to produce force which manifest immediately and persist for up to 14 days following exercise exposure. IIMD has been implicated in attenuated neuromuscular performance and recovery with inflammatory process implicated, although the underlying time course remains unclear. Exposure to EIMD leads to an adaptation to subsequent exposures, a phenomenon known as the repeated-bout effect. An analogous adaptation has been suggested to occur following IIMD, however, to date this contention remains equivocal. Whilst a considerable body of research has explored the efficacy of recovery strategies following EIMD, strategies promoting recovery from IIMD are limited to investigations using animal contusion models. Strategies such as cryotherapy and antioxidant supplementation, which focus on attenuating the secondary inflammatory response may provide additional benefit in IIMD and are explored herein. Further research is required to firstly establish a model of generating IIMD and then explore broader areas around IIMD in athletic populations.

Heterotrophic bacteria in drinking water distribution system: a review.

PubMed

Chowdhury, Shakhawat

2012-10-01

The microbiological quality of drinking water in municipal water distribution systems (WDS) depends on several factors. Free residual chlorine and/or chloramines are typically used to minimize bacterial recontamination and/or regrowth in WDS. Despite such preventive measures, regrowth of heterotrophic (HPC) and opportunistic bacteria in bulk water and biofilms has yet to be controlled completely. No approach has shown complete success in eliminating biofilms or HPC bacteria from bulk water and pipe surfaces. Biofilms can provide shelter for pathogenic bacteria and protect these bacteria from disinfectants. Some HPC bacteria may be associated with aesthetic and non-life threatening diseases. Research to date has achieved important success in understanding occurrence and regrowth of bacteria in bulk water and biofilms in WDS. To achieve comprehensive understanding and to provide efficient control against bacteria regrowth, future research on bacteria regrowth dynamics and their implications is warranted. In this study, a review was performed on the literature published in this area. The findings and limitations of these papers are summarized. Occurrences of bacteria in WDS, factors affecting bacteria regrowth in bulk water and biofilms, bacteria control strategies, sources of nutrients, human health risks from bacterial exposure, modelling of bacteria regrowth and methods of bacteria sampling and detection and quantification are investigated. Advances to date are noted, and future research needs are identified. Finally, research directions are proposed to effectively control HPC and opportunistic bacteria in bulk water and biofilms in WDS.

Low Earth orbit atomic oxygen simulation for durability evaluation of solar reflector surfaces

NASA Technical Reports Server (NTRS)

Degroh, Kim K.; Banks, Bruce A.

1992-01-01

To evaluate the performance and durability of solar reflector surfaces in the atomic oxygen environment typical of low Earth orbit (LEO), one must expose the reflector surface either directly to LEO or to ground-laboratory atomic oxygen environments. Although actual LEO exposures are most desired, such opportunities are typically scarce, expensive, and of limited duration. As a result, ground-laboratory exposures must be relied upon as the most practical long-term durability evaluation technique. Plasma ashers are widely used as LEO simulation facilities by producing atomic oxygen environments for durability evaluation of potential spacecraft materials. Atomic oxygen arrival differs between ground and space exposure in that plasma asher exposure produces isotropic arrival and space solar tracking produces sweeping arrival. Differences in initial impact reaction probability occur, dependent upon the energy and species existing in these environments. Due to the variations in ground-laboratory and space atomic oxygen, quantification of in-space performance based on plasma asher testing is not straightforward. The various atomic oxygen interactions that can occur with reflector surfaces, such as undercutting in organic substrates at protective coating defect sites, ground-laboratory techniques recommended for evaluating the atomic oxygen durability of reflectors based on asher exposures, and computational techniques which make use of ground-laboratory atomic oxygen exposure to predict in-space LEO durability are addressed.

Analysis of the Early Stages and Evolution of Dental Enamel Erosion.

PubMed

Derceli, Juliana Dos Reis; Faraoni, Juliana Jendiroba; Pereira-da-Silva, Marcelo Assumpção; Palma-Dibb, Regina Guenka

2016-01-01

The aim of this study was to evaluate by atomic force microscopy (AFM) the early phases and evolution of dental enamel erosion caused by hydrochloric acid exposure, simulating gastroesophageal reflux episodes. Polished bovine enamel slabs (4x4x2 mm) were selected and exposed to 0.1 mL of 0.01 M hydrochloric acid (pH=2) at 37 ?#61472;?#61616;C using five different exposure intervals (n=1): no acid exposure (control), 10 s, 20 s, 30 s and 40 s. The exposed area was analyzed by AFM in 3 regions to measure the roughness, surface area and morphological surface. The data were analyzed qualitatively. Roughness started as low as that of the control sample, Rrms=3.5 nm, and gradually increased at a rate of 0.3 nm/s, until reaching Rrms=12.5 nm at 30 s. After 40 s, the roughness presented increment of 0.40 nm only. Surface area (SA) increased until 20 s, and for longer exposures, the surface area was constant (at 30 s, SA=4.40 μm2 and at 40 s, SA=4.43 μm2). As regards surface morphology, the control sample presented smaller hydroxyapatite crystals (22 nm) and after 40 s the crystal size was approximately 60 nm. Short periods of exposure were sufficient to produce enamel demineralization in different patterns and the morphological structure was less affected by exposure to hydrochloric acid over 30 s.

75 FR 14483 - Third Meeting: RTCA Special Committee 223: Airport Surface Wireless Communications

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-25

... 223: Airport Surface Wireless Communications AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 223: Airport Surface Wireless Communications meeting. SUMMARY...: Airport Surface Wireless Communications. DATES: The meeting will be held April 13-14, 2010 from 9 a.m.-5 p...

Improvement and extension of a radar forest backscattering model

NASA Technical Reports Server (NTRS)

Simonett, David S.; Wang, Yong

1988-01-01

Research to-date has focused on modeling development and programming based on model components proposed during the past several months and research progress made by the Simonett team. The model components and programs (in C language under UNIX) finished to date are summarized. These model components may help explain the contributions of various vegetation structural components to the attenuation and backscattering of vegetated surfaces to extract useful data concerning forest stands and their underlying surfaces for both the seawater-on and seawater-off.

Space environmental effects on silvered Teflon thermal control surfaces

NASA Technical Reports Server (NTRS)

Hemminger, C. S.; Stuckey, W. K.; Uht, J. C.

1991-01-01

Cumulative space environment effects on Ag/fluorinated ethylene propylene (FEP) were a function of exposure orientation. Samples from nineteen silvered Teflon (Ag/FEP) thermal control surfaces recovered from the Long Duration Exposure Facility (LDEF) were analyzed to determine changes in this material as a function of position on the spacecraft. Although solar absorptance and infrared emittance of measured thermal blanket specimens are relatively unchanged from control specimen values, significant changes in surface morphology, composition and chemistry were observed. Researchers hypothesize that the FEP surfaces on LDEF were degraded by ultraviolet radiation exposure at all orientations, but that the damaged material had been removed by erosion from the blankets exposed to atomic oxygen flux and that contamination is masking the damage on trays flanking the trailing edge.

78 FR 13338 - Exposure Modeling Public Meeting; Notice of Public Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-27

... code 22 Professional, Scientific and Technical NAICS code 54 B. How can I get copies of this document... dates and abstract requests are announced through the ``empmlist'' forum on the LYRIS list server at...

Dating of Submarine Landslides and Their Tsunami Deposits Using Hawaii as an Example

NASA Astrophysics Data System (ADS)

McMurtry, G. M.; Herrero-Bervera, E.

2003-12-01

There have been several approaches to dating the initiation of submarine landslides and the tsunamis they inevitably produce. In Hawaii, the timing of flank failures of major volcanoes has been estimated by radiometric and paleomagnetic dating of the youngest shield-building flows and dikes, the apex ages of the volcanoes, which can also be constrained by the oldest flows of post-collapse volcanism. More precise age estimates can be obtained by direct dating of the landslide. These approaches include paleomagnetic and U-series stratigraphic dating of the overlying pelagic sediment cover upon and in front of the landslide, the latter method producing minimum ages of last landslide turbidite emplacement, e.g., the ca. 120 ka Alika phase 2 event. Elevated, detached landslide blocks make the best targets for such dating because it is assumed that smaller post-emplacement turbidites will not reach their summits. Catastrophic events such as the 1.0 Ma Wailau giant landslide have, however, been dated by turbidite deposition upon large, elevated blocks of the nearby 1.8 Ma Nuuanu giant landslide. Other direct methods for older events include use of thickness of ferromanganese crusts collected from steep, exposed rock scarps and cosmogenic Be-10 or U-series radiometric determination of the few mm/Ma rate of accumulation. In subtropical areas such as Hawaii, coral clast-bearing, elevated marine deposits on the southeastern islands have been identified as deposits from giant tsunamis. Among the key evidence are the great age and paleo-elevations of the coral clasts found in situ. Since modern coral clasts are relatively young, a few thousand years old or less, older analogs swept from the presently submerged reefs offshore can reliably date tsunamigenic depositional events within the late Quaternary using U-series methods. The age of the tsunami will date within these limits (and the analytical precisions) to the youngest in situ coral clast that was entrained by the waves. U-series dates approximately coeval with the Alika 2 giant landslide suggest a youngest 100 ka tsunami emplacement age from 100-137 ka corals collected on Lanai and Hawaii; likewise, older deposits on Molokai and Lanai suggest a 200 ka tsunami emplacement age from corals that range 200-258 ka in age, but interpretative care must be taken as open-system behavior upon weathering may produce apparently younger dates. Other promising methods for dating these deposits include cosmogenic Cl-36 exposure ages of cements and Cl-36 and He-3 exposure ages of the entrained volcanic rocks. Younger events can be dated by the above methods using C-14 or unsupported Pb-210.

The Diesel Exhaust in Miners study: a nested case-control study of lung cancer and diesel exhaust.

PubMed

Silverman, Debra T; Samanic, Claudine M; Lubin, Jay H; Blair, Aaron E; Stewart, Patricia A; Vermeulen, Roel; Coble, Joseph B; Rothman, Nathaniel; Schleiff, Patricia L; Travis, William D; Ziegler, Regina G; Wacholder, Sholom; Attfield, Michael D

2012-06-06

Most studies of the association between diesel exhaust exposure and lung cancer suggest a modest, but consistent, increased risk. However, to our knowledge, no study to date has had quantitative data on historical diesel exposure coupled with adequate sample size to evaluate the exposure-response relationship between diesel exhaust and lung cancer. Our purpose was to evaluate the relationship between quantitative estimates of exposure to diesel exhaust and lung cancer mortality after adjustment for smoking and other potential confounders. We conducted a nested case-control study in a cohort of 12 315 workers in eight non-metal mining facilities, which included 198 lung cancer deaths and 562 incidence density-sampled control subjects. For each case subject, we selected up to four control subjects, individually matched on mining facility, sex, race/ethnicity, and birth year (within 5 years), from all workers who were alive before the day the case subject died. We estimated diesel exhaust exposure, represented by respirable elemental carbon (REC), by job and year, for each subject, based on an extensive retrospective exposure assessment at each mining facility. We conducted both categorical and continuous regression analyses adjusted for cigarette smoking and other potential confounding variables (eg, history of employment in high-risk occupations for lung cancer and a history of respiratory disease) to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Analyses were both unlagged and lagged to exclude recent exposure such as that occurring in the 15 years directly before the date of death (case subjects)/reference date (control subjects). All statistical tests were two-sided. We observed statistically significant increasing trends in lung cancer risk with increasing cumulative REC and average REC intensity. Cumulative REC, lagged 15 years, yielded a statistically significant positive gradient in lung cancer risk overall (P (trend) = .001); among heavily exposed workers (ie, above the median of the top quartile [REC ≥ 1005 μg/m(3)-y]), risk was approximately three times greater (OR = 3.20, 95% CI = 1.33 to 7.69) than that among workers in the lowest quartile of exposure. Among never smokers, odd ratios were 1.0, 1.47 (95% CI = 0.29 to 7.50), and 7.30 (95% CI = 1.46 to 36.57) for workers with 15-year lagged cumulative REC tertiles of less than 8, 8 to less than 304, and 304 μg/m(3)-y or more, respectively. We also observed an interaction between smoking and 15-year lagged cumulative REC (P (interaction) = .086) such that the effect of each of these exposures was attenuated in the presence of high levels of the other. Our findings provide further evidence that diesel exhaust exposure may cause lung cancer in humans and may represent a potential public health burden.

The relationship between inadvertent ingestion and dermal exposure pathways: a new integrated conceptual model and a database of dermal and oral transfer efficiencies.

PubMed

Gorman Ng, Melanie; Semple, Sean; Cherrie, John W; Christopher, Yvette; Northage, Christine; Tielemans, Erik; Veroughstraete, Violaine; Van Tongeren, Martie

2012-11-01

Occupational inadvertent ingestion exposure is ingestion exposure due to contact between the mouth and contaminated hands or objects. Although individuals are typically oblivious to their exposure by this route, it is a potentially significant source of occupational exposure for some substances. Due to the continual flux of saliva through the oral cavity and the non-specificity of biological monitoring to routes of exposure, direct measurement of exposure by the inadvertent ingestion route is challenging; predictive models may be required to assess exposure. The work described in this manuscript has been carried out as part of a project to develop a predictive model for estimating inadvertent ingestion exposure in the workplace. As inadvertent ingestion exposure mainly arises from hand-to-mouth contact, it is closely linked to dermal exposure. We present a new integrated conceptual model for dermal and inadvertent ingestion exposure that should help to increase our understanding of ingestion exposure and our ability to simultaneously estimate exposure by the dermal and ingestion routes. The conceptual model consists of eight compartments (source, air, surface contaminant layer, outer clothing contaminant layer, inner clothing contaminant layer, hands and arms layer, perioral layer, and oral cavity) and nine mass transport processes (emission, deposition, resuspension or evaporation, transfer, removal, redistribution, decontamination, penetration and/or permeation, and swallowing) that describe event-based movement of substances between compartments (e.g. emission, deposition, etc.). This conceptual model is intended to guide the development of predictive exposure models that estimate exposure from both the dermal and the inadvertent ingestion pathways. For exposure by these pathways the efficiency of transfer of materials between compartments (for example from surfaces to hands, or from hands to the mouth) are important determinants of exposure. A database of transfer efficiency data relevant for dermal and inadvertent ingestion exposure was developed, containing 534 empirically measured transfer efficiencies measured between 1980 and 2010 and reported in the peer-reviewed and grey literature. The majority of the reported transfer efficiencies (84%) relate to transfer between surfaces and hands, but the database also includes efficiencies for other transfer scenarios, including surface-to-glove, hand-to-mouth, and skin-to-skin. While the conceptual model can provide a framework for a predictive exposure assessment model, the database provides detailed information on transfer efficiencies between the various compartments. Together, the conceptual model and the database provide a basis for the development of a quantitative tool to estimate inadvertent ingestion exposure in the workplace.

Effects of exposure, diet, and thermoregulation on fecal glucocorticoid measures in wild bears.

PubMed

Stetz, Jeff; Hunt, Kathleen; Kendall, Katherine C; Wasser, Samuel K

2013-01-01

We examined fecal glucocorticoid (fGC) measures of nutrition and thermoregulatory demands on wild bears in Glacier National Park, Montana, and assessed how these measures changed in samples left in the field. Both ambient temperature and exposure can impact thermoregulation and sample degradation. Bear diets vary markedly with season, affecting body condition and thus fGC. We collected fecal samples during September and October, 2001, when ambient temperatures ranged from 30°C to -5°C. We collected half of each sample immediately and left the other half in its original location for 1-28 days. We used generalized linear models (GLM) to first predict fGC concentrations in fresh samples based on proxies of nutrition, ambient temperature, thermal exposure, and precipitation. These same covariates were then used to predict degradation-based differences in fGC concentrations between the paired sample halves. Variation in fGC was predicted by diet, Julian date, aspect, and the interaction between Julian date and aspect in both fresh and exposed samples. Cumulative precipitation was also a significant predictor of fGC concentrations in the exposed samples, independent of time, indicating that precipitation contributes to sample degradation but not enough to mask effects of other environmental factors on fGC concentrations. Differences between sample halves were only predicted by cumulative precipitation and exposure time; cumulative precipitation decreased, whereas exposure time increased, fGC concentrations in the exposed sample halves. Results indicate that fGC can provide reliable indices of nutrition and thermoregulatory demands in bears and that sample degradation impacts on these relations are minimal and can be virtually eliminated by controlling for cumulative precipitation over the estimated exposure times.

Effects of Exposure, Diet, and Thermoregulation on Fecal Glucocorticoid Measures in Wild Bears

PubMed Central

Stetz, Jeff; Hunt, Kathleen; Kendall, Katherine C.; Wasser, Samuel K.

2013-01-01

We examined fecal glucocorticoid (fGC) measures of nutrition and thermoregulatory demands on wild bears in Glacier National Park, Montana, and assessed how these measures changed in samples left in the field. Both ambient temperature and exposure can impact thermoregulation and sample degradation. Bear diets vary markedly with season, affecting body condition and thus fGC. We collected fecal samples during September and October, 2001, when ambient temperatures ranged from 30°C to −5°C. We collected half of each sample immediately and left the other half in its original location for 1–28 days. We used generalized linear models (GLM) to first predict fGC concentrations in fresh samples based on proxies of nutrition, ambient temperature, thermal exposure, and precipitation. These same covariates were then used to predict degradation-based differences in fGC concentrations between the paired sample halves. Variation in fGC was predicted by diet, Julian date, aspect, and the interaction between Julian date and aspect in both fresh and exposed samples. Cumulative precipitation was also a significant predictor of fGC concentrations in the exposed samples, independent of time, indicating that precipitation contributes to sample degradation but not enough to mask effects of other environmental factors on fGC concentrations. Differences between sample halves were only predicted by cumulative precipitation and exposure time; cumulative precipitation decreased, whereas exposure time increased, fGC concentrations in the exposed sample halves. Results indicate that fGC can provide reliable indices of nutrition and thermoregulatory demands in bears and that sample degradation impacts on these relations are minimal and can be virtually eliminated by controlling for cumulative precipitation over the estimated exposure times. PMID:23457488

Low-Temperature Plasma Coating for Aluminum

DTIC Science & Technology

2001-03-01

AFRL-ML-WP-TR-2001-4104 LOW-TEMPERATURE PLASMA COATING FOR ALUMINUM DR. HIROTSUGU YASUDA CENTER FOR SURFACE SCIENCE & PLASMA TECHNOLOGY...Date 00032001 Report Type N/A Dates Covered (from... to) - Title and Subtitle Low-Temperature Plasma Coating for Aluminum Contract Number...REPORT TYPE AND DATES COVERED Final, 6/29/1996 - 3/31/2001 4. TITLE AND SUBTITLE LOW-TEMPERATURE PLASMA COATING FOR ALUMINUM 5. FUNDING NUMBERS C

Assessing the biological impact of exposure to environmental surface waters with cell-based lipidomics

EPA Science Inventory

Environmental surface waters often contain a variety of chemical contaminants from different sources including wastewater treatment plants, concentrated animal feeding operations, agricultural runoff and other human-related activities. Exposure to these contaminants may pose a th...

PESTICIDE TRANSFER EFFICIENCY FROM HOUSEHOLD SURFACES TO FOODS

EPA Science Inventory

Application of pesticides around homes presents a potential for exposure to young children. Contaminated surfaces can be contacted by children's hands or foods which could allow transfer of pesticides. The exposures caused by these contacts are uncertain because the amount of pes...

77 FR 64185 - Railroad Revenue Adequacy-2011 Determination

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-18

...)] Railroad Revenue Adequacy--2011 Determination AGENCY: Surface Transportation Board. ACTION: Notice of... determinations for the Nation's Class I railroads. Two carriers, Norfolk Southern Combined Railroad Subsidiaries and Union Pacific Railroad Company, were found to be revenue adequate. DATES: Effective Date: This...

Advances in Satellite Remote Sensing of Particulate Air Pollution: From MISR to MAIA

NASA Astrophysics Data System (ADS)

Diner, D. J.; Burke, K.; Xu, F.; Garay, M. J.; Kalashnikova, O. V.; Liu, Y.; Meng, X.; Wang, J.; Martin, R.; Ostro, B.

2017-12-01

Airborne particulate matter (PM) is a well-known cause of cardiovascular and respiratory disease. To estimate human exposure to PM pollution, satellite instruments such as the Terra Multi-angle Imaging SpectroRadiometer (MISR) and the Moderate resolution Imaging Spectroradiometer (MODIS) have been used in conjunction with surface monitors to map near-surface PM concentrations. The relative toxicity of different size and compositional mixtures of PM is not well understood. To address this, we are developing the Multi-Angle Imager for Aerosols (MAIA) investigation. The satellite instrument extends MISR's multiangular visible and near-infrared (VNIR) spectral coverage to 14 bands in the ultraviolet, VNIR, and shortwave IR; three of the bands are polarimetric to enhance sensitivity to aerosol size and composition. To constrain the retrievals, the observations will be combined with data from surface monitors and the WRF-Chem and GEOS-Chem chemical transport models. Existing surface PM speciation monitors will be supplemented by adding new stations to the Surface PARTiculate mAtter Network (SPARTAN). Unlike MISR, MAIA is a targeting instrument. Primary areas of interest include metropolitan areas in North and South America, Europe, the Middle East, Africa, India, and East Asia. PM retrieval algorithms are being developed using data from MISR and the high-altitude Airborne Multiangle SpectroPolarimetric Imager (AirMSPI). Epidemiologists on the MAIA science team will use the derived PM data products and birth, death, and hospital records to investigate adverse health impacts of different types of airborne particulates. MAIA's earliest possible launch date is mid-2020, making it possible for the data to be complemented by global observations from Terra as well as high temporal resolution atmospheric chemistry measurements from TEMPO (Tropospheric Emissions: Monitoring Pollution), GEMS (Geostationary Environment Monitoring Spectrometer), and Sentinel-4.

Chemical films and monolayers on the water surface and their interactions with ultraviolet radiation: a pilot investigation

NASA Astrophysics Data System (ADS)

Schouten, Peter; Lemckert, Charles; Turnbull, David; Parisi, Alfio; Downs, Nathan; Underhill, Ian; Turner, Geoff

2011-06-01

Over the past 50 years numerous types of chemical films and monolayers have been deployed on top of a wide variety of water reserves in an endeavour to reduce evaporation. To date very little knowledge has been assimilated on how these chemical films and monolayers, once applied to a water surface, influence the underwater UV light field and, in turn, the delicate ecosystems that exist in aquatic environments. This manuscript presents underwater UV exposure profiles weighted to the DNA damage action spectrum measured under an octadecanol/hexadecanol/lime chemical film mixture, a silicone-based chemical film and an octadecanol monolayer applied to the water surface. UV transmission and absorption properties were also evaluated for each of these chemical films and monolayers. From this it was found that when chemical films/monolayers are applied to surface water they can reduce the penetration of biologically effective UV into the water column by up to 85% at a depth as small as 1 cm. This could have a positive influence on the aquatic ecosystem, as harmful UV radiation may be prevented from reaching and consequently damaging a variety of life forms or it could have a negative effect by potentially stopping aquatic organisms from adapting to solar ultraviolet radiation over extended application intervals. Additionally, there is currently no readily applicable system or technique available to readily detect or visualize chemical films and monolayers on the water surface. To overcome this problem a new method of monolayer and chemical film visualization, using a UV camera system, is detailed and tested and its applicability for usage in both laboratory-based trials and real-world operations is evaluated.

Predicting Residential Exposure to Phthalate Plasticizer Emitted from Vinyl Flooring: Sensitivity, Uncertainty, and Implications for Biomonitoring

PubMed Central

Xu, Ying; Cohen Hubal, Elaine A.; Little, John C.

2010-01-01

Background Because of the ubiquitous nature of phthalates in the environment and the potential for adverse human health effects, an urgent need exists to identify the most important sources and pathways of exposure. Objectives Using emissions of di(2-ethylhexyl) phthalate (DEHP) from vinyl flooring (VF) as an illustrative example, we describe a fundamental approach that can be used to identify the important sources and pathways of exposure associated with phthalates in indoor material. Methods We used a three-compartment model to estimate the emission rate of DEHP from VF and the evolving exposures via inhalation, dermal absorption, and oral ingestion of dust in a realistic indoor setting. Results A sensitivity analysis indicates that the VF source characteristics (surface area and material-phase concentration of DEHP), as well as the external mass-transfer coefficient and ventilation rate, are important variables that influence the steady-state DEHP concentration and the resulting exposure. In addition, DEHP is sorbed by interior surfaces, and the associated surface area and surface/air partition coefficients strongly influence the time to steady state. The roughly 40-fold range in predicted exposure reveals the inherent difficulty in using biomonitoring to identify specific sources of exposure to phthalates in the general population. Conclusions The relatively simple dependence on source and chemical-specific transport parameters suggests that the mechanistic modeling approach could be extended to predict exposures arising from other sources of phthalates as well as additional sources of other semivolatile organic compounds (SVOCs) such as biocides and flame retardants. This modeling approach could also provide a relatively inexpensive way to quantify exposure to many of the SVOCs used in indoor materials and consumer products. PMID:20123613

Predicting residential exposure to phthalate plasticizer emitted from vinyl flooring: sensitivity, uncertainty, and implications for biomonitoring.

PubMed

Xu, Ying; Cohen Hubal, Elaine A; Little, John C

2010-02-01

Because of the ubiquitous nature of phthalates in the environment and the potential for adverse human health effects, an urgent need exists to identify the most important sources and pathways of exposure. Using emissions of di(2-ethylhexyl) phthalate (DEHP) from vinyl flooring (VF) as an illustrative example, we describe a fundamental approach that can be used to identify the important sources and pathways of exposure associated with phthalates in indoor material. We used a three-compartment model to estimate the emission rate of DEHP from VF and the evolving exposures via inhalation, dermal absorption, and oral ingestion of dust in a realistic indoor setting. A sensitivity analysis indicates that the VF source characteristics (surface area and material-phase concentration of DEHP), as well as the external mass-transfer coefficient and ventilation rate, are important variables that influence the steady-state DEHP concentration and the resulting exposure. In addition, DEHP is sorbed by interior surfaces, and the associated surface area and surface/air partition coefficients strongly influence the time to steady state. The roughly 40-fold range in predicted exposure reveals the inherent difficulty in using biomonitoring to identify specific sources of exposure to phthalates in the general population. The relatively simple dependence on source and chemical-specific transport parameters suggests that the mechanistic modeling approach could be extended to predict exposures arising from other sources of phthalates as well as additional sources of other semivolatile organic compounds (SVOCs) such as biocides and flame retardants. This modeling approach could also provide a relatively inexpensive way to quantify exposure to many of the SVOCs used in indoor materials and consumer products.

Surface transport mechanisms in molecular glasses probed by the exposure of nano-particles

NASA Astrophysics Data System (ADS)

Ruan, Shigang; Musumeci, Daniele; Zhang, Wei; Gujral, Ankit; Ediger, M. D.; Yu, Lian

2017-05-01

For a glass-forming liquid, the mechanism by which its surface contour evolves can change from bulk viscous flow at high temperatures to surface diffusion at low temperatures. We show that this mechanistic change can be conveniently detected by the exposure of nano-particles native in the material. Despite its high chemical purity, the often-studied molecular glass indomethacin contains low-concentration particles approximately 100 nm in size and 0.3% in volume fraction. Similar particles are present in polystyrene, another often-used model. In the surface-diffusion regime, particles are gradually exposed in regions vacated by host molecules, for example, the peak of a surface grating and the depletion zone near a surface crystal. In the viscous-flow regime, particle exposure is not observed. The surface contour around an exposed particle widens over time in a self-similar manner as 3 (Bt)1/4, where B is a surface mobility constant and the same constant obtained by surface grating decay. This work suggests that in a binary system composed of slow- and fast-diffusing molecules, slow-diffusing molecules can be stranded in surface regions vacated by fast-diffusing molecules, effectively leading to phase separation.

Global Pressure and Temperature Surface Measurements on a NACA 0012 Airfoil in Oscillatory Compressible Flow at Low Reduced Frequencies

DTIC Science & Technology

2012-01-01

clc close all clear all% tic %% for looping for dateN= 1:2 %% pick a date if dateN==1 date=󈧏.21.11’ runS=2; runE =28...else date=󈧏.23.11’ runS=1; runE =32; end %% for looping for run=runS:runE %% Number of images per run ImageE...date=󈧏.21.11’ runS=2; runE =28; ImageE=[0 100 59 59 59 59 100 59 59 59 59 59 100 59 59 59 59 100 59 59 59 59 100 59 59 59 59 100 0 0 0 0

Turbulent Boundary Layer Flow over Superhydrophobic Surfaces

DTIC Science & Technology

2013-05-10

DATES COVERED (From - To) 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Turbulent Boundary Layer Flow over Superhydrophobic ...modified surfaces. This study encompassed the testing of four different surfaces: 1) Teflon SLIP, 2) Aluminum SLIP, 3) Honeycomb Superhydrophobic and 4...Polydimethylsiloxane elastomer (PDMSe) Superhydrophobic . Each of these surfaces uses specific geometrical surface features to modify the original

Differential exposure, duration, and sensitivity of unionoidean bivalve life stages to environmental contaminants

USGS Publications Warehouse

Cope, W.G.; Bringolf, R.B.; Buchwalter, D.B.; Newton, T.J.; Ingersoll, C.G.; Wang, N.; Augspurger, T.; Dwyer, F.J.; Barnhart, M.C.; Neves, R.J.; Hammer, E.

2008-01-01

Freshwater mussels (superfamily Unionoidea) are in serious global decline and in urgent need of protection and conservation. The declines have been attributed to a wide array of human activities resulting in pollution and water-quality degradation, and habitat destruction and alteration. Linkages among poor water quality, pollutant sources, and mussel decline in rivers and streams have been associated with results of laboratory-based tests of specific pollutants. However, uncertainties remain about the relationship of laboratory data to actual contaminant exposure routes for various mussel species, life stages, and in the habitats occupied during these exposures. We evaluated the pathways of exposure to environmental pollutants for all 4 life stages (free glochidia, encysted glochidia, juveniles, adults) of unionoidean mussels and found that each life stage has both common and unique characteristics that contribute to observed differences in exposure and sensitivity. Free glochidia typically are exposed only briefly (e.g., seconds to days) through surface water, whereas adults sustain exposure over years to decades through surface water, pore water, sediment, and diet. Juveniles live largely burrowed in the sediment for the first 0 to 4 y of life. Thus, sediment, pore water, and diet are the predominant exposure routes for this life stage, but surface water also might contribute to exposure during certain periods and environmental conditions. The obligate parasitic stage (encysted glochidia stage) on a host fish might be exposed from surface water while partially encysted or from toxicants in host-fish tissue while fully encysted. Laboratory methods for testing for acute and chronic exposures in water have advanced, and toxicant-specific information has increased in recent years. However, additional research is needed to understand interactions of life history, habitat, and long-term exposure to contaminants through water, pore water, sediment, and diet so that the risks of environmental exposures can be properly assessed and managed. ?? 2008 by The North American Benthological Society.

The Risk of Pneumonia in Older Adults Using Nonbenzodiazepine Hypnotics.

PubMed

Jung, Stephen; Spence, Michele M; Escasa, Nina M; Lee, Eric A; Hui, Rita L; Gibbs, Nancy E

2016-08-01

Previous studies have shown an increased risk of pneumonia with benzodiazepines (BZD) and an increased risk of any infection with non-BZD hypnotics, but no analysis has specifically investigated the risk of pneumonia with non-BZD hypnotic use. To evaluate the risk of pneumonia associated with non-BZD hypnotic use in the elderly. This was a retrospective case-control study of members aged 65 years and older enrolled in an integrated health care system. Cases were identified as patients aged 65 years and older with a diagnosis of pneumonia from January 2011 to December 2012. Controls were matched in a 4:1 ratio to cases based on age, gender, and active enrollment. Non-BZD hypnotic exposure was evaluated for all cases and controls 1 year before the index date. Proximity of exposure to index date and duration of use were analyzed. Conditional logistic regression adjusted for covariates was performed. We identified 51,029 cases with pneumonia and matched 188,391 controls without pneumonia. Of the cases with pneumonia, 5.5% (2,790) of cases had exposure to a non-BZD hypnotic, compared with 3.4% (6,345) of controls. Non-BZD hypnotic exposure was associated with an increased risk of pneumonia (OR = 1.14; 95% CI = 1.08-1.20). When exposure was stratified by proximity to index date, only current exposure was associated with an increased risk of pneumonia (OR = 1.27; 95% CI = 1.18-1.36). Short-term exposure was associated with a relatively higher risk of pneumonia (OR = 1.57; 95% CI = 1.39-1.77) compared with long-term use (OR = 1.16; 95% CI = 1.06-1.25). Current use of non-BZD hypnotics in older adults is associated with an increased risk of pneumonia. The findings of this study provide additional support for reducing the use of non-BZD hypnotics in older adults and for pursuing safer alternatives for treating insomnia. No outside funding supported this study. At the time of this study, Jung was a PGY2 resident in drug information at Kaiser Permanente Drug Information Services. All authors are employed by Kaiser Permanente and report no other potential financial conflicts of interest. Study concept and design were contributed by Jung, Spence, Lee, and Gibbs. Jung, Spence, and Hui were responsible for data collection, and data interpretation was performed by Jung and Spence, with assistance from Escasa, Lee, and Hui. The manuscript was primarily written by Jung, along with Spence and Escasa, and revised by Spence, Escasa, and Lee, along with the other authors.

Silica dust exposures during selected construction activities.

PubMed

Flanagan, Mary Ellen; Seixas, Noah; Majar, Maria; Camp, Janice; Morgan, Michael

2003-01-01

This study characterized exposure for dust-producing construction tasks. Eight common construction tasks were evaluated for quartz and respirable dust exposure by collecting 113 personal task period samples for cleanup; demolition with handheld tools; concrete cutting; concrete mixing; tuck-point grinding; surface grinding; sacking and patching concrete; and concrete floor sanding using both time-integrating filter samples and direct-reading respirable dust monitors. The geometric mean quartz concentration was 0.10 mg/m(3) (geometric standard deviation [GSD]=4.88) for all run time samples, with 71% exceeding the threshold limit value. Activities with the highest exposures were surface grinding, tuck-point grinding, and concrete demolition (GM[GSD] of 0.63[4.12], 0.22[1.94], and 0.10[2.60], respectively). Factors recorded each minute were task, tool, work area, respiratory protection and controls used, estimated cross draft, and whether anyone nearby was making dust. Factors important to exposure included tool used, work area configuration, controls employed, cross draft, and in some cases nearby dust. More protective respirators were employed as quartz concentration increased, although respiratory protection was found to be inadequate for 42% of exposures. Controls were employed for only 12% of samples. Exposures were reduced with three controls: box fan for surface grinding and floor sanding, and vacuum/shroud for surface grinding, with reductions of 57, 50, and 71%, respectively. Exposures were higher for sweeping compound, box fan for cleanup, ducted fan dilution, and wetted substrate. Construction masons and laborers are frequently overexposed to silica. The usual protection method, respirators, was not always adequate, and engineering control use was infrequent and often ineffective.

Comparison of Extracellular Striatal Acetylcholine and Brain Seizure Activity Following Acute Exposure to the Nerve Agents Cyclosarin and Tabun in Freely Moving Guinea Pigs

DTIC Science & Technology

2010-01-01

Literature 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Comparison of extracellular striatal acetylcholine and brain seizure activity following...lethality; nerve agents; organophosphorus compounds; seizure activity ; tabun 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER...acetylcholine and brain seizure activity following acute exposure to the nerve agents cyclosarin and tabun in freely moving guinea pigs John C

Reconstructive microsurgery of the female reproductive tract using a CO 2 laser

NASA Astrophysics Data System (ADS)

Bellina, J. H.

1982-04-01

Laser tubal microsurgery was carried out on a sample of 82 patients. Employing current laser surgical systems, 21 conceptions occured in 20 patients, after limited exposure to conception risk during the 13-month study. This represents 48% of the 42 patients at risk. Tubal patency was demonstrated in 94% of the 82 cases. Based upon experience to date, more conceptions are expected as more patients become at risk and as exposure increases.

Surface Cleaning Techniques: Ultra-Trace ICP-MS Sample Preparation and Assay of HDPE

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

Overman, Nicole R.; Hoppe, Eric W.; Addleman, Raymond S.

2013-06-01

The world’s most sensitive radiation detection and assay systems depend upon ultra-low background (ULB) materials to reduce unwanted radiological backgrounds. Herein, we evaluate methods to clean HDPE, a material of interest to ULB systems and the means to provide rapid assay of surface and bulk contamination. ULB level material and ultra-trace level detection of actinide elements is difficult to attain, due to the introduction of contamination from sample preparation equipment such as pipette tips, sample vials, forceps, etc. and airborne particulate. To date, literature available on the cleaning of such polymeric materials and equipment for ULB applications and ultra-trace analysesmore » is limited. For these reasons, a study has been performed to identify an effective way to remove surface contamination from polymers in an effort to provide improved instrumental detection limits. Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) was utilized to assess the effectiveness of a variety of leachate solutions for removal of inorganic uranium and thorium surface contamination from polymers, specifically high density polyethylene (HDPE). HDPE leaching procedures were tested to optimize contaminant removal of thorium and uranium. Calibration curves for thorium and uranium ranged from 15 ppq (fg/mL) to 1 ppt (pg/mL). Detection limits were calculated at 6 ppq for uranium and 7 ppq for thorium. Results showed the most effective leaching reagent to be clean 6 M nitric acid for 72 hour exposures. Contamination levels for uranium and thorium found in the leachate solutions were significant for ultralow level radiation detection applications.« less

Evidence of alloy formation during reduction of platinized tin oxide surfaces

NASA Technical Reports Server (NTRS)

Gardner, Steven D.; Hoflund, Gar B.; Davidson, Mark R.; Schryer, David R.

1989-01-01

Ion scattering spectroscopy, Auger electron spectroscopy, and electron spectroscopy for chemical analysis have been used to examine a platinized tin oxide catalyst surface before, during, and after reduction by annealing under vacuum at 250 to 450 C. These techniques were then used to examine the reduced surface after a room-temperature, low-pressure oxygen exposure. The spectral results and the behavior of the reduced surface toward oxygen exposure both indicate that a Pt/Sn alloy is produced during reduction.

Do Gender and Exposure to Interparental Violence Moderate the Stability of Teen Dating Violence?: Latent Transition Analysis.

PubMed

Choi, Hye Jeong; Temple, Jeff R

2016-04-01

This study investigates the development, change, and stability of teen dating violence (TDV) victimization over time. Specifically, we identify distinct subgroups of adolescents based on past-year TDV victimization, whether adolescents change victimization statuses over time (e.g., from psychological victimization to physical victimization), and how exposure to interparental violence and gender influence the prevalence and stability of TDV statuses. Adolescents (N=1,042) from 7 public high schools in Texas participated in this longitudinal study. The Conflict in Adolescent Dating Relationships Inventory (CADRI) (Wolfe et al., Psychological Assessment, 13(2), 277-293, 2001) was used to identify victimization statuses. Latent Transition Analysis (LTA) with measurement invariance was used to examine transition probability of an individual's latent status at Wave3 or Wave4 given his or her latent status at Wave2 or Wave3. Gender and exposure to interparental violence was included as moderators in the LTA. Three statuses of TDV victimization were identified: (1) non-victims; (2) emotional/verbal victims; and (3) physical/psychological victims. LTA showed that the majority of adolescents stayed in the same status over time; however, female youth exposed to interparental violence were more likely to move from a less to more severe status over time compared to non-exposed youth. This is among the first study to identify subgroups of TDV victimization and to examine the stability of group membership over time. Female youth exposed to interparental violence were more likely to remain in or move into a violent relationship compared to unexposed youth.

Assessing chemical exposure and ecological impacts of environmental surface waters using cell culture-based metabolomic

EPA Science Inventory

Waste water treatment plants (WWTPs), as well as industrial and agricultural operations release complex mixtures of anthropogenic chemicals that negatively affect surface water quality. Previous studies have shown that exposure to such complex chemical mixtures can produce adver...

Effects of High Temperature Exposures on Fatigue Life of Disk Superalloys

NASA Technical Reports Server (NTRS)

Gabb, Tim P.; Telesman, Jack; Kantzos, Pete T.; Smith, James W.; Browning, Paul F.

2004-01-01

The effects on fatigue life of high temperature exposures simulating service conditions were considered for two disk superalloys. Powder metallurgy processed, supersolvus heat treated Udimet (trademark) 720 and ME3 fatigue specimens were exposed in air at temperatures of 650 to 704 C, for times of 100 h to over 1000 h. They were then tested using conventional fatigue tests at 650 and 704 C, to determine the effects of exposure on fatigue resistance. Cyclic dwell verification tests were also performed to contrast the effects of intermixed exposures and fatigue cycles. The prior exposures reduced life by up to 70% and increased the scatter in life, compared to unexposed levels. Cyclic dwell tests reduced lives even more. Fractographic evaluations indicated the failure mode was shifted by the exposures and cyclic dwells from predominantly internal to often surface crack initiations. The increased scatter in life was related to the competition between internal crack initiations at inclusions or large grains producing longer lives, and surface crack initiations at an environmentally affected surface layer producing shorter lives.

Photochemical effects in the lens from near infrared radiation?

NASA Astrophysics Data System (ADS)

Söderberg, Per G.; Al-Saqry, Riyadh; Schulmeister, Karl; Gallichanin, Konstantin; Kronschläger, Martin; Yu, Zhaohua

2009-02-01

Conclusion: The current data are consistent with a potential photochemical effect of in vivo exposure of the crystalline lens to near infrared radiation since the onset of cataract after in just above threshold dose was at least 18 hrs delayed after the exposure. Materials and methods: The eyes of 6 weeks old Sprague-Dawley rats were exposed unilaterally in vivo to 1090 nm, 6.2 W quasi-top hat spatial distribution with a 3 mm spot on the anterior lens surface within the dilated pupil. First, four exposure time groups of rats were exposed to increasing exposure times. At 24 hrs after exposure, the difference of light scattering between the lenses from the same animal was measured. Then, based on the first experiment, four post-exposure time groups were exposed unilaterally in vivo to 8 s of 1090 nm, 6.2 W quasi-top hat spatial distribution with a 3 mm spot on the anterior lens surface within the dilated pupil. After, the intended post-exposure time, the difference of light scattering between the lenses from the same animal was measured. Results: A 3 mm spot of 6.2 W induces light scattering in the lens with exposures of at least 8 s. Further, after 8 s of 6.2 W within a 3 mm spot on the lens surface, the light scattering increase in the lens was delayed at least 18 hrs after the exposure.

Deglaciation chronology in the Mérida Andes from cosmogenic 10Be dating, (Gavidia valley, Venezuela)

NASA Astrophysics Data System (ADS)

Angel, Isandra; Audemard M., Franck A.; Carcaillet, Julien; Carrillo, Eduardo; Beck, Christian; Audin, Laurence

2016-11-01

In the Mérida Andes, a detailed deglaciation history reconstruction is difficult to achieve due to scattered deglaciation chronologies available. This paper contributes with 24 exposure ages of glacial landforms sampled in the Gavidia valley. Exposure ages were obtained based on terrestrial cosmogenic nuclide 10Be dating. Results indicate deglaciation mainly occurred between ∼21 ka and 16.5 ka and the complete deglaciation occurred at ∼16.0 ka. The glacier retreated in two different phases. The oldest one occurred since the LGM until middle OtD or the local climate event El Caballo Stadial. The youngest phase occurred at ages younger than ∼16.5 ka until complete deglaciation. A combination of topographic features and changes in the paleoclimate conditions at the end of the El Caballo Stadial seems leaded the fastest former glacier extinction. The topographic feature which seems contributed to the fastest glacier extinction was the low valley bottom slopes. In addition, exposure ages of the Gavidia valley were integrated with deglaciation chronologies from the central Mérida Andes to compare deglaciation histories. Asynchronous deglaciation histories were observed. Local paleotemperatures and paleoprecipitations contrasts, different valleys aspects, insolation and catchments steepness could explain different deglaciation histories.

A longitudinal test of video game violence influences on dating and aggression: a 3-year longitudinal study of adolescents.

PubMed

Ferguson, Christopher J; San Miguel, Claudia; Garza, Adolfo; Jerabeck, Jessica M

2012-02-01

In 2011 the field of video game violence experienced serious reversals with repudiations of the current research by the US Supreme Court and the Australian Government as non-compelling and fundamentally flawed. Scholars too have been calling for higher quality research on this issue. The current study seeks to answer this call by providing longitudinal data on youth aggression and dating violence as potential consequences of violent video game exposure using well-validated clinical outcome measures and controlling for other relevant predictors of youth aggression. A sample of 165, mainly Hispanic youth, were tested at 3 intervals, an initial interview, and 1-year and 3-year intervals. Results indicated that exposure to video game violence was not related to any of the negative outcomes. Depression, antisocial personality traits, exposure to family violence and peer influences were the best predictors of aggression-related outcomes. The current study supports a growing body of evidence pointing away from video game violence use as a predictor of youth aggression. Public policy efforts, including funding, would best be served by redirecting them toward other prevention programs for youth violence. Copyright © 2011 Elsevier Ltd. All rights reserved.

78 FR 65601 - Revised Filing Deadlines Following Resumption of Normal Commission Operations; 2014 Modification...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-01

... of Exposure to Radiofrequency Electromagnetic Fields Limits and Policies AGENCY: Federal... Electromagnetic Fields Limits and Policies, ET Docket Nos. 03-137 and 13-84; FCC 13-39. The date for filing reply...

New incision rates along the Colorado River system based on cosmogenic burial dating of terraces: implications for regional controls on differential incision

NASA Astrophysics Data System (ADS)

Darling, A. L.; Karlstrom, K. E.; Granger, D. E.; Aslan, A.; Kirby, E.; Ouimet, W. B.; Coblentz, D. D.; Crest Working Group

2010-12-01

The Green and Colorado Rivers comprise the main drainage system of the western slope of the Colorado Rockies and Colorado Plateau. In this region we compare river profiles and incision rates between these rivers to resolve controls on river evolution. Disequilibrium profiles in both rivers are evident by numerous knickpoints and convexities which we analyze in the context of a new compilation of incision rate data, including new isochron cosmogenic burial dates on early Quaternary terraces. The Lees Ferry knickpoint is interpreted to be an upstream-migrating knickpoint initiated by integration of the Colorado system through Grand Canyon about 6 Ma. An isochron cosmogenic burial date of 1.5 +/-0.13 Ma, on a 190-m-high strath terrace at Bullfrog Marina 169 km northeast of the knickpoint indicates an incision rate of 126 m/Ma. This date is 3x older than a cosmogenic surface date from the same terrace suggesting that high terraces dated by surface cosmogenic techniques are minimum dates. Available incision rates across the Lee’s Ferry knickpoint show rates of 150- 175 m/Ma below Lees Ferry and ca. 100- 130 m/Ma above the knickpoint (over 0.5 to 1 Ma) above. A burial date of 2.9 +0.7/-0.5 on a 110 m terrace that is 70 km farther upstream at Hite Crossing is problematic because the strath is lower, the date older, and the rate slower than nearby Bullfrog. The Hite data show significantly more scatter, and additional samples have been collected to clarify the age. Ca. 300-500 m/Ma rates within and above the knickpoint based on cosmogenic surface dates (with the caution these are maximum rates), suggest acceleration of incision rates in the late Quaternary due to a pulse of diffuse knickpoint propagation extending to several hundred km above Lees Ferry in the last few hundred-thousand years, as suggested by Cook et al. (2009). On the Green River, a new isochron cosmogenic burial date of 1.48 +/-0.12 Ma on an abandoned meander 60 m above the river in upper Desolation Canyon gives an incision rate of 40 m/Ma. Thus, the Green River displays much slower incision rates relative to the Colorado River, both from reaches equidistant upstream from their confluence and within the Colorado Plateau. The combination of higher gradient, higher discharge and higher incision rates over the last several million years for the upper Colorado River, relative to the Green, suggests differential rock uplift of the Colorado Rockies relative to the Colorado Plateau in the Quaternary. This may be driven by mantle flow and buoyancy associated with the Aspen Anomaly of central Colorado and is consistent with the strong correlation between mantle-uplift driving forces and surface topographic expression.

Does the Economy or Surface Warfare Officer Career Pay Affect Surface Warfare Officer Retention?

DTIC Science & Technology

2014-12-01

be a career SWO (Surface Warfare Enterprise, 2013). 6 Military pay was more important to men than women ...OR SURFACE WARFARE OFFICER CAREER PAY AFFECT SURFACE WARFARE OFFICER RETENTION? by Meagan B. Makarenko December 2014 Thesis Advisor...2014 3. REPORT TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE DOES THE ECONOMY OR SURFACE WARFARE OFFICER CAREER PAY AFFECT

Investigation of He-W interactions using DiMES on DIII-D

NASA Astrophysics Data System (ADS)

Doerner, R. P.; Rudakov, D. L.; Chrobak, C. P.; Briesemeister, A. R.; Corr, C.; De Temmerman, G.; Kluth, P.; Lasnier, C. J.; McLean, A. G.; Pace, D. C.; Pitts, R. A.; Schmitz, O.; Thompson, M.; Winters, V.

2016-02-01

Tungsten button samples were exposed to He ELMing H-mode plasma in DIII-D using 2.3 MW of electron cyclotron heating power. Prior to the exposures, the W buttons were exposed to either He, or D, plasma in PISCES-A for 2000 s at surface temperatures of 225-850 °C to create a variety of surfaces (surface blisters, subsurface nano-bubbles, fuzz). Erosion was spectroscopically measured from each DiMES sample, with the exception of the fuzzy W samples which showed almost undetectable WI emission. Post-exposure grazing incidence small angle x-ray scattering surface analysis showed the formation of 1.5 nm diameter He bubbles in the surface of W buttons after only a single DIII-D (3 s, ˜150 ELMs) discharge, similar to the bubble layer resulting from the 2000 s. exposure in PISCES-A. No surface roughening, or damage, was detected on the samples after approximately 600 ELMs with energy density between 0.04-0.1 MJ m-2.

Modification of the Surface Properties of Polyimide Films using POSS Deposition and Oxygen Plasma Exposure

NASA Technical Reports Server (NTRS)

Wohl, Christopher J.; Belcher, Marcus A.; Ghose, Sayata; Connell, John W.

2008-01-01

Topographically rich surfaces were generated by spray-coating organic solutions of a polyhedral oligomeric silsesquioxane, octakis (dimethylsilyloxy) silsesquioxane (POSS), on Kapton HN films and exposing them to radio frequency generated oxygen plasma. Changes in both surface chemistry and topography were observed. High-resolution scanning electron microscopy indicated substantial modification of the POSS-coated polyimide surface topographies as a result of oxygen plasma exposure. Water contact angles varied from 104 deg for unexposed POSS-coated surfaces to approximately 5 deg, for samples exposed for 5 h. Modulation of the dispersive and polar contributions to the surface energy was determined using van Oss Good Chaudhury theory.

40 CFR 264.1085 - Standards: Surface impoundments.

Code of Federal Regulations, 2014 CFR

2014-07-01

... effects of outdoor exposure to wind, moisture, and sunlight; and the operating practices used for the... outdoor exposure to wind, moisture, and sunlight; and the operating practices used for the surface... condition. (3) The owner or operator shall inspect and monitor the air emission control equipment in...

40 CFR 265.1086 - Standards: Surface impoundments.

Code of Federal Regulations, 2013 CFR

2013-07-01

... effects of outdoor exposure to wind, moisture, and sunlight; and the operating practices used for the... outdoor exposure to wind, moisture, and sunlight; and the operating practices used for the surface... unsafe condition. (3) The owner or operator shall inspect and monitor the air emission control equipment...

40 CFR 264.1085 - Standards: Surface impoundments.

Code of Federal Regulations, 2012 CFR

2012-07-01

... effects of outdoor exposure to wind, moisture, and sunlight; and the operating practices used for the... outdoor exposure to wind, moisture, and sunlight; and the operating practices used for the surface... condition. (3) The owner or operator shall inspect and monitor the air emission control equipment in...

40 CFR 265.1086 - Standards: Surface impoundments.

Code of Federal Regulations, 2014 CFR

2014-07-01

... effects of outdoor exposure to wind, moisture, and sunlight; and the operating practices used for the... outdoor exposure to wind, moisture, and sunlight; and the operating practices used for the surface... unsafe condition. (3) The owner or operator shall inspect and monitor the air emission control equipment...

40 CFR 265.1086 - Standards: Surface impoundments.

Code of Federal Regulations, 2012 CFR

2012-07-01

... effects of outdoor exposure to wind, moisture, and sunlight; and the operating practices used for the... outdoor exposure to wind, moisture, and sunlight; and the operating practices used for the surface... unsafe condition. (3) The owner or operator shall inspect and monitor the air emission control equipment...

40 CFR 264.1085 - Standards: Surface impoundments.

Code of Federal Regulations, 2013 CFR

2013-07-01

... effects of outdoor exposure to wind, moisture, and sunlight; and the operating practices used for the... outdoor exposure to wind, moisture, and sunlight; and the operating practices used for the surface... condition. (3) The owner or operator shall inspect and monitor the air emission control equipment in...

40 CFR 264.1085 - Standards: Surface impoundments.

Code of Federal Regulations, 2011 CFR

2011-07-01

... effects of outdoor exposure to wind, moisture, and sunlight; and the operating practices used for the... outdoor exposure to wind, moisture, and sunlight; and the operating practices used for the surface... condition. (3) The owner or operator shall inspect and monitor the air emission control equipment in...

40 CFR 265.1086 - Standards: Surface impoundments.

Code of Federal Regulations, 2011 CFR

2011-07-01

... effects of outdoor exposure to wind, moisture, and sunlight; and the operating practices used for the... outdoor exposure to wind, moisture, and sunlight; and the operating practices used for the surface... unsafe condition. (3) The owner or operator shall inspect and monitor the air emission control equipment...

Contextual Risk Profiles and Trajectories of Adolescent Dating Violence Perpetration.

PubMed

Reyes, H Luz McNaughton; Foshee, Vangie A; Markiewitz, Nathan; Chen, May S; Ennett, Susan T

2018-04-09

Social ecological and developmental system perspectives suggest that interactions among factors within and across multiple contexts (e.g., neighborhood, peer, family) must be considered in explaining dating violence perpetration. Yet, to date, most extant research on dating violence has focused on individual, rather than contextual predictors, and used variable-centered approaches that fail to capture the configurations of factors that may jointly explain involvement in dating violence. The current study used a person-centered approach, latent profile analysis, to identify key configurations (or profiles) of contextual risk and protective factors for dating violence perpetration across the neighborhood, school, friend and family contexts. We then examine the longitudinal associations between these contextual risk profiles, assessed during middle school, and trajectories of psychological and physical dating violence perpetration across grades 8 through 12. Five contextual risk profiles were identified: school, neighborhood, and family risk; school and family risk; school and friend risk; school and neighborhood risk; and low risk. The highest levels of psychological and physical perpetration across grades 8 through 12 were among adolescents in the profile characterized by high levels of school, neighborhood, and family risk. Results suggest that early interventions to reduce violence exposure and increase social regulation across multiple social contexts may be effective in reducing dating violence perpetration across adolescence.

Thermal control surfaces experiment: Initial flight data analysis

NASA Technical Reports Server (NTRS)

Wilkes, Donald R.; Hummer, Leigh L.

1991-01-01

The behavior of materials in the space environment continues to be a limiting technology for spacecraft and experiments. The thermal control surfaces experiment (TCSE) aboard the Long Duration Exposure Facility (LDEF) is the most comprehensive experiment flown to study the effects of the space environment on thermal control surfaces. Selected thermal control surfaces were exposed to the LDEF orbital environment and the effects of this exposure were measured. The TCSE combined in-space orbital measurements with pre and post-flight analyses of flight materials to determine the effects of long term space exposure. The TCSE experiment objective, method, and measurements are described along with the results of the initial materials analysis. The TCSE flight system and its excellent performance on the LDEF mission is described. A few operational anomalies were encountered and are discussed.

Correlated topographic and structural modification on Si surface during multi-shot femtosecond laser exposures: Si nanopolymorphs as potential local structural nanomarkers

NASA Astrophysics Data System (ADS)

Ionin, A. A.; Kudryashov, S. I.; Levchenko, A. O.; Nguyen, L. V.; Saraeva, I. N.; Rudenko, A. A.; Ageev, E. I.; Potorochin, D. V.; Veiko, V. P.; Borisov, E. V.; Pankin, D. V.; Kirilenko, D. A.; Brunkov, P. N.

2017-09-01

High-pressure Si-XII and Si-III nanocrystalline polymorphs, as well as amorphous Si phase, appear consequently during multi-shot femtosecond-laser exposure of crystalline Si wafer surface above its spallation threshold along with permanently developing quasi-regular surface texture (ripples, microcones), residual hydrostatic stresses and subsurface damage, which are characterized by scanning and transmission electron microscopy, as well as by Raman micro-spectroscopy. The consequent yields of these structural Si phases indicate not only their spatially different appearance, but also potentially enable to track nanoscale, transient laser-induced high-pressure, high-temperature physical processes - local variation of ablation mechanism and rate, pressurization/pressure release, melting/resolidification, amorphization, annealing - versus cumulative laser exposure and the related development of the surface topography.

Low earth orbit durability evaluation of Haynes 188 solar receiver material

NASA Technical Reports Server (NTRS)

De Groh, Kim K.; Rutledge, Sharon K.; Burke, Christopher A.; Dever, Therese M.; Olle, Raymond M.; Terlep, Judith A.

1992-01-01

The effects of elevated-temperature vacuum and elevated-temperature atomic oxygen exposure on the mass, surface chemistry, surface morphology, and optical properties of Haynes 188, a possible heat receiver material for space-based solar dynamic power systems, have been studied. Pristine and surface modified Haynes 188 were exposed to vacuum less than or equal to 10 exp -6 torr at 820 C for 5215.5 h, and to atomic oxygen in an air plasma asher at 34 and 827 C for fluences up to 5.6 x 10 exp 21 atoms/sq cm. Results obtained indicate that vacuum heat treatment caused surface morphology and chemistry changes with corresponding optical property changes. Atomic oxygen exposure caused optical property changes which diminished with time. Mass changes are considered to be negligible for both exposures.

Beryllium surface levels in a military ammunition plant.

PubMed

Sanderson, Wayne T; Leonard, Stephanie; Ott, Darrin; Fuortes, Laurence; Field, William

2008-07-01

This study evaluated the presence of beryllium surface contamination in a U.S. conventional munitions plant as an indicator of possible past beryllium airborne and skin exposure and used these measurements to classify job categories by potential level of exposure. Surface samples were collected from production and nonproduction areas of the plant and at regional industrial reference sites with no known history of beryllium use. Surface samples of premoistened wiping material were analyzed for beryllium mass content using inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and results expressed as micrograms of beryllium per 100 square centimeters (micro g/100 cm(2)). Beryllium was detected in 87% of samples collected at the munitions plant and in 72% of the samples collected at regional reference sites. Two munitions plant samples from areas near sanders and grinders were above 3.0 micro g/100 cm(2) (U.S. Department of Energy surface contamination limit). The highest surface level found at the reference sites was 0.44 micro g/100 cm(2). Workers in areas where beryllium-containing alloy tools were sanded or ground, but not other work areas, may have been exposed to airborne beryllium concentrations above levels encountered in other industries where metal work is conducted. Surface sampling provided information useful for categorizing munitions plant jobs by level of past beryllium airborne and skin exposure and, subsequently, for identifying employees within exposure strata to be screened for beryllium sensitization.

Optical and electrical properties of ion beam textured Kapton and Teflon

NASA Technical Reports Server (NTRS)

Mirtich, M. J.; Sovey, J. S.

1977-01-01

An electron bombardment argon ion source was used to ion etch polyimide (Kapton) and fluorinated ethylene, FEP (Teflon). Samples of polyimide and FEP were exposed to (0.5-1.0) keV Ar ions at ion current densities of (1.0-1/8) mA/sq cm for various exposure times. Changes in the optical and electrical properties of the samples were used to characterize the exposure. Spectral reflectance and transmittance measurements were made between 0.33 and 2.16 micron m using an integrating sphere after each exposure. From these measurements, values of solar absorptance were obtained. Total emittance measurements were also recorded for some samples. Surface resistivity was used to determine changes in the electrical conductivity of the etched samples. A scanning electron microscope recorded surface structure after exposure. Spectral optical data, resistivity measurements, calculated absorptance and emittance measurements are presented along with photomicrographs of the surface structure for the various exposures to Ar ions.

Comparative Risk Assessment of spill response options for a deepwater oil well blowout: Part 1. Oil spill modeling.

PubMed

French-McCay, Deborah; Crowley, Deborah; Rowe, Jill J; Bock, Michael; Robinson, Hilary; Wenning, Richard; Walker, Ann Hayward; Joeckel, John; Nedwed, Tim J; Parkerton, Thomas F

2018-06-01

Oil spill model simulations of a deepwater blowout in the Gulf of Mexico De Soto Canyon, assuming no intervention and various response options (i.e., subsea dispersant injection SSDI, in addition to mechanical recovery, in-situ burning, and surface dispersant application) were compared. Predicted oil fate, amount and area of surfaced oil, and exposure concentrations in the water column above potential effects thresholds were used as inputs to a Comparative Risk Assessment to identify response strategies that minimize long-term impacts. SSDI reduced human and wildlife exposure to volatile organic compounds; dispersed oil into a large water volume at depth; enhanced biodegradation; and reduced surface water, nearshore and shoreline exposure to floating oil and entrained/dissolved oil in the upper water column. Tradeoffs included increased oil exposures at depth. However, since organisms are less abundant below 200 m, results indicate that overall exposure of valued ecosystem components was minimized by use of SSDI. Copyright © 2018 Elsevier Ltd. All rights reserved.

Assessing occupational exposure to sea lamprey pesticides.

PubMed

Ceballos, Diana M; Beaucham, Catherine C; Kurtz, Kristine; Musolin, Kristin

2015-01-01

Sea lampreys are parasitic fish found in lakes of the United States and Canada. Sea lamprey is controlled through manual application of the pesticides 3-trifluoromethyl-4-nitrophenol (TFM) and Bayluscide(TM) into streams and tributaries. 3-Trifluoromethyl-4-nitrophenol may cause irritation and central nervous system depression and Bayluscide may cause irritation, dermatitis, blisters, cracking, edema, and allergic skin reactions. To assess occupational exposures to sea lamprey pesticides. We developed a wipe method for evaluating surface and skin contamination with these pesticides. This method was field tested at a biological field station and at a pesticide river application. We also evaluated exposures using control banding tools. We verified TFM surface contamination at the biological station. At the river application, we found surfaces and worker's skin contaminated with pesticides. We recommended minimizing exposures by implementing engineering controls and improved use of personal protective equipment.

78 FR 79008 - Proposed Information Collection; Application for Waiver of Surface Sanitary Facilities...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-27

... Information Collection; Application for Waiver of Surface Sanitary Facilities' Requirements (Pertaining to... for Waiver of Surface Sanitary Facilities' Requirements (Pertaining to Coal Mines). DATES: All...-3 require coal mine operators to provide bathing facilities, clothing change rooms, and sanitary...

Occupational Exposure to Cobalt and Tungsten in the Swedish Hard Metal Industry: Air Concentrations of Particle Mass, Number, and Surface Area

PubMed Central

Bryngelsson, Ing-Liss; Pettersson, Carin; Husby, Bente; Arvidsson, Helena; Westberg, Håkan

2016-01-01

Exposure to cobalt in the hard metal industry entails severe adverse health effects, including lung cancer and hard metal fibrosis. The main aim of this study was to determine exposure air concentration levels of cobalt and tungsten for risk assessment and dose–response analysis in our medical investigations in a Swedish hard metal plant. We also present mass-based, particle surface area, and particle number air concentrations from stationary sampling and investigate the possibility of using these data as proxies for exposure measures in our study. Personal exposure full-shift measurements were performed for inhalable and total dust, cobalt, and tungsten, including personal real-time continuous monitoring of dust. Stationary measurements of inhalable and total dust, PM2.5, and PM10 was also performed and cobalt and tungsten levels were determined, as were air concentration of particle number and particle surface area of fine particles. The personal exposure levels of inhalable dust were consistently low (AM 0.15mg m−3, range <0.023–3.0mg m−3) and below the present Swedish occupational exposure limit (OEL) of 10mg m−3. The cobalt levels were low as well (AM 0.0030mg m−3, range 0.000028–0.056mg m−3) and only 6% of the samples exceeded the Swedish OEL of 0.02mg m−3. For continuous personal monitoring of dust exposure, the peaks ranged from 0.001 to 83mg m−3 by work task. Stationary measurements showed lower average levels both for inhalable and total dust and cobalt. The particle number concentration of fine particles (AM 3000 p·cm−3) showed the highest levels at the departments of powder production, pressing and storage, and for the particle surface area concentrations (AM 7.6 µm2·cm−3) similar results were found. Correlating cobalt mass-based exposure measurements to cobalt stationary mass-based, particle area, and particle number concentrations by rank and department showed significant correlations for all measures except for particle number. Linear regression analysis of the same data showed statistically significant regression coefficients only for the mass-based aerosol measures. Similar results were seen for rank correlation in the stationary rig, and linear regression analysis implied significant correlation for mass-based and particle surface area measures. The mass-based air concentration levels of cobalt and tungsten in the hard metal plant in our study were low compared to Swedish OELs. Particle number and particle surface area concentrations were in the same order of magnitude as for other industrial settings. Regression analysis implied the use of stationary determined mass-based and particle surface area aerosol concentration as proxies for various exposure measures in our study. PMID:27143598

Retrospective evaluation of exposure index (EI) values from plain radiographs reveals important considerations for quality improvement

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

Mothiram, Ursula; Brennan, Patrick C; Robinson, John

2013-12-15

Following X-ray exposure, radiographers receive immediate feedback on detector exposure in the form of the exposure index (EI). To identify whether radiographers are meeting manufacturer-recommended EI (MREI) ranges for routine chest, abdomen and pelvis X-ray examinations under a variety of conditions and to examine factors affecting the EI. Data on 5000 adult X-ray examinations including the following variables were collected: examination parameters, EI values, patient gender, date of birth, date and time of examination, grid usage and the presence of implant or prosthesis. Descriptive statistics were used to summarize each data set and the Mann–Whitney U test was used tomore » determine significant differences, with P < 0.05 indicating significance for all tests. Most examinations demonstrated EI values that were outside the MREI ranges, with significantly higher median EI values recorded for female patient radiographs than those for male patients for all manufacturers, indicating higher detector exposures for all units except for Philips digital radiography (DR), where increased EI values indicate lower exposure (P = 0.01). Median EI values for out of hours radiography were also significantly higher compared with normal working hours for all technologies (P ≤ 0.02). Significantly higher median EI values were demonstrated for Philips DR chest X-rays without as compared to those with the employment of a grid (P = 0.03), while significantly lower median EI values were recorded for Carestream Health computed radiography (CR) chest X-rays when an implant or prosthesis was present (P = 0.02). Non-adherence to MREIs has been demonstrated with EI value discrepancies being dependent on patient gender, time/day of exposure, grid usage and the presence of an implant or prosthesis. Retrospective evaluation of EI databases is a valuable tool to assess the need of quality improvement in routine DR.« less

A stand-replacing fire history in upper montane forests of the southern Rocky Mountains

USGS Publications Warehouse

Margolis, E.Q.; Swetnam, T.W.; Allen, Craig D.

2007-01-01

Dendroecological techniques were applied to reconstruct stand-replacing fire history in upper montane forests in northern New Mexico and southern Colorado. Fourteen stand-replacing fires were dated to 8 unique fire years (1842–1901) using four lines of evidence at each of 12 sites within the upper Rio Grande Basin. The four lines of evidence were (i) quaking aspen (Populus tremuloides Michx.) inner-ring dates, (ii) fire-killed conifer bark-ring dates, (iii) tree-ring width changes or other morphological indicators of injury, and (iv) fire scars. The annual precision of dating allowed the identification of synchronous stand-replacing fire years among the sites, and co-occurrence with regional surface fire events previously reconstructed from a network of fire scar collections in lower elevation pine forests across the southwestern United States. Nearly all of the synchronous stand-replacing and surface fire years coincided with severe droughts, because climate variability created regional conditions where stand-replacing fires and surface fires burned across ecosystems. Reconstructed stand-replacing fires that predate substantial Anglo-American settlement in this region provide direct evidence that stand-replacing fires were a feature of high-elevation forests before extensive and intensive land-use practices (e.g., logging, railroad, and mining) began in the late 19th century.

Optimization of Sugar Replacement with Date Syrup in Prebiotic Chocolate Milk Using Response Surface Methodology.

PubMed

Kazemalilou, Sahar; Alizadeh, Ainaz

2017-01-01

Chocolate milk is one of the most commonly used non-fermentative dairy products, which, due to high level of sucrose, could lead to diabetes and tooth decay among children. Therefore, it is important to replace sucrose with other types of sweeteners, especially, natural ones. In this research, response surface methodology (RSM) was used to optimize the ingredients formulation of prebiotic chocolate milk, date syrup as sweetener (4-10%w/w), inulin as prebiotic texturizer (0-0.5%w/w) and carrageenan as thickening agent (0-0.04%w/w) in the formulation of chocolate milk. The fitted models to predict the variables of selected responses such as pH, viscosity, total solid, sedimentation and overall acceptability of chocolate milk showed a high coefficient of determination. The independent effect of carrageenan was the most effective parameter which led to pH and sedimentation decrease but increased viscosity. Moreover, in most treatments, date syrup and inulin variables had significant effects which had a mutual impact. Optimization of the variables, based on the responses surface 3D plots showed that the sample containing 0.48% (w/w) of inulin, 0.04% (w/w) of carrageenan, and 10% of date syrup was selected as the optimum condition.

Earlier vegetation green-up has reduced spring dust storms.

PubMed

Fan, Bihang; Guo, Li; Li, Ning; Chen, Jin; Lin, Henry; Zhang, Xiaoyang; Shen, Miaogen; Rao, Yuhan; Wang, Cong; Ma, Lei

2014-10-24

The observed decline of spring dust storms in Northeast Asia since the 1950s has been attributed to surface wind stilling. However, spring vegetation growth could also restrain dust storms through accumulating aboveground biomass and increasing surface roughness. To investigate the impacts of vegetation spring growth on dust storms, we examine the relationships between recorded spring dust storm outbreaks and satellite-derived vegetation green-up date in Inner Mongolia, Northern China from 1982 to 2008. We find a significant dampening effect of advanced vegetation growth on spring dust storms (r = 0.49, p = 0.01), with a one-day earlier green-up date corresponding to a decrease in annual spring dust storm outbreaks by 3%. Moreover, the higher correlation (r = 0.55, p < 0.01) between green-up date and dust storm outbreak ratio (the ratio of dust storm outbreaks to times of strong wind events) indicates that such effect is independent of changes in surface wind. Spatially, a negative correlation is detected between areas with advanced green-up dates and regional annual spring dust storms (r = -0.49, p = 0.01). This new insight is valuable for understanding dust storms dynamics under the changing climate. Our findings suggest that dust storms in Inner Mongolia will be further mitigated by the projected earlier vegetation green-up in the warming world.

Effect of 25 cycles of launch pad exposure and simulated mission heating on space shuttle reusable surface insulation coated with reaction cured glass

NASA Technical Reports Server (NTRS)

Ransone, P. O.; Morrison, J. D.; Minster, J. E.

1979-01-01

Tiles of space shuttle reusable surface insulation coated with reaction cured glass were subjected to 25 cycles of launch pad exposure and simulated mission heating. The coating could not withstand the environment without cracking. Water absorption after cracking reached as high as 150 weight percent. Exposure of insulation fibers beneath the coating to contaminants dissolved in absorbed water initiated fiber degradation.

Survival of Pochonia chlamydosporia on the soil surface after different exposure intervals at ambient conditions.

PubMed

Fernandes, Rafael Henrique; Lopes, Everaldo Antônio; Borges, Darlan Ferreira; Bontempo, Amanda Ferreira; Zanuncio, José Cola; Serrão, José Eduardo

Exposure of the nematophagous fungus Pochonia chlamydosporia to solar radiation and elevated temperatures before being incorporated into the soil can reduce its survival and efficiency as biocontrol agent. A field experiment was carried out to assess the effect of the exposure period on the viability of P. chlamydosporia applied on the soil surface. A commercial bionematicide based on P. chlamydosporia was sprayed on soil, and soil samples were collected before and at 0, 30, 60, 90, 120, and 150min after fungal application. Relative humidity (RH), the irradiance (IR), air temperature (AT), and soil temperature (ST) were recorded. The number of P. chlamydosporia colony forming units (CFUs) was evaluated after 20 days of incubation. P. chlamydosporia survival decreased over the time of exposure on the soil surface. Overall, the number of CFUs decreased by more than 90% at 150min after application. Exposure to RH ≥61%, ST and AT between 25-35°C and 19-29°C, and IR between 1172 and 2126μmol of photons m -2 s -1 induced a negative exponential effect on the survival of the fungus over the time. Exposure to climatic conditions on the soil surface reduces P. chlamydosporia viability. Copyright © 2017 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

Surface Luminescence Dating Of 'Dragon Houses' And Armena Gate At Styra (Euboea, Greece)

NASA Astrophysics Data System (ADS)

Liritzis, I.; Polymeris, G. S.; Zacharias, N.

The Optical Stimulated Luminescence (OSL) surface dating employing the singlealiquot regenerative (SAR) technique on quartz was applied to some small enigmatic buildings made of large marble schist slabs in a skillful corbelling technique, and a fortified megalithic gate, at Styra, Kapsala, Laka Palli and Kastro Armena in southern Euboea. The function and origins of the structures have created a puzzle that has fed the imagination and lead to various interpretations by many scholars. No archaeological excavations or methods of dating have been available for the megalithic-like structures. The dates reported suggest the earliest construction to have taken place during the Classical period. Re-use of these structures has occurred during Hellenistic and Roman times (the latter associated with the large scale quarrying of marbles), as well as, in Medieval times (found in agreement with the historical literature) and the contemporary period (as reported by shepherds). In all cases the datable slabs were rather reset as repairs.

Synchrotron macro ATR-FTIR microspectroscopic analysis of silica nanoparticle-embedded polyester coated steel surfaces subjected to prolonged UV and humidity exposure

PubMed Central

Vongsvivut, Jitraporn; Truong, Vi Khanh; Al Kobaisi, Mohammad; Maclaughlin, Shane; Tobin, Mark J.; Crawford, Russell J.

2017-01-01

Surface modification of polymers and paints is a popular and effective way to enhance the properties of these materials. This can be achieved by introducing a thin coating that preserves the bulk properties of the material, while protecting it from environmental exposure. Suitable materials for such coating technologies are inorganic oxides, such as alumina, titania and silica; however, the fate of these materials during long-term environmental exposure is an open question. In this study, polymer coatings that had been enhanced with the addition of silica nanoparticles (SiO2NPs) and subsequently subjected to environmental exposure, were characterized both before and after the exposure to determine any structural changes resulting from the exposure. High-resolution synchrotron macro ATR-FTIR microspectroscopy and surface topographic techniques, including optical profilometry and atomic force microscopy (AFM), were used to determine the long-term effect of the environment on these dual protection layers after 3 years of exposure to tropical and sub-tropical climates in Singapore and Queensland (Australia). Principal component analysis (PCA) based on the synchrotron macro ATR-FTIR spectral data revealed that, for the 9% (w/w) SiO2NP/polymer coating, a clear discrimination was observed between the control group (no environmental exposure) and those samples subjected to three years of environmental exposure in both Singapore and Queensland. The PCA loading plots indicated that, over the three year exposure period, a major change occurred in the triazine ring vibration in the melamine resins. This can be attributed to the triazine ring being very sensitive to hydrolysis under the high humidity conditions in tropical/sub-tropical environments. This work provides the first direct molecular evidence, acquired using a high-resolution mapping technique, of the climate-induced chemical evolution of a polyester coating. The observed changes in the surface topography of the coating are consistent with the changes in chemical composition. PMID:29253012

Synchrotron macro ATR-FTIR microspectroscopic analysis of silica nanoparticle-embedded polyester coated steel surfaces subjected to prolonged UV and humidity exposure.

PubMed

Vongsvivut, Jitraporn; Truong, Vi Khanh; Al Kobaisi, Mohammad; Maclaughlin, Shane; Tobin, Mark J; Crawford, Russell J; Ivanova, Elena P

2017-01-01

Surface modification of polymers and paints is a popular and effective way to enhance the properties of these materials. This can be achieved by introducing a thin coating that preserves the bulk properties of the material, while protecting it from environmental exposure. Suitable materials for such coating technologies are inorganic oxides, such as alumina, titania and silica; however, the fate of these materials during long-term environmental exposure is an open question. In this study, polymer coatings that had been enhanced with the addition of silica nanoparticles (SiO2NPs) and subsequently subjected to environmental exposure, were characterized both before and after the exposure to determine any structural changes resulting from the exposure. High-resolution synchrotron macro ATR-FTIR microspectroscopy and surface topographic techniques, including optical profilometry and atomic force microscopy (AFM), were used to determine the long-term effect of the environment on these dual protection layers after 3 years of exposure to tropical and sub-tropical climates in Singapore and Queensland (Australia). Principal component analysis (PCA) based on the synchrotron macro ATR-FTIR spectral data revealed that, for the 9% (w/w) SiO2NP/polymer coating, a clear discrimination was observed between the control group (no environmental exposure) and those samples subjected to three years of environmental exposure in both Singapore and Queensland. The PCA loading plots indicated that, over the three year exposure period, a major change occurred in the triazine ring vibration in the melamine resins. This can be attributed to the triazine ring being very sensitive to hydrolysis under the high humidity conditions in tropical/sub-tropical environments. This work provides the first direct molecular evidence, acquired using a high-resolution mapping technique, of the climate-induced chemical evolution of a polyester coating. The observed changes in the surface topography of the coating are consistent with the changes in chemical composition.

Visualization of UV exposure of the human body based on data from a scanning UV-measuring system.

PubMed

Hoeppe, P; Oppenrieder, A; Erianto, C; Koepke, P; Reuder, J; Seefeldner, M; Nowak, D

2004-09-01

In general, measurements of UV radition are related to horizontal surfaces, as in the case of the internationally standardized and applied UV index, for example. In order to obtain more relevant information on UV exposure of humans the new measuring system ASCARATIS (Angle SCAnning RAdiometer for determination of erythemally weighted irradiance on TIlted Surfaces) was developed and built. Three systems of ASCARATIS have been in operation at different locations in Bavaria for 3 years, providing erythemally weighted UV irradiation data for 27 differently inclined surfaces every 2 min. On the basis of these data virtual three-dimensional models of the human body surface consisting of about 20,000 triangles could be created and each of these triangles coloured according to its UV irradiation. This allowed the UV exposure of the human body to be visualized for any kind of body posture and spatial orientation on the basis of real measuring data. The results of the UV measurements on inclined surfaces have shown that measuring UV radiation on horizontal surfaces, as done routinely worldwide, often underestimates the UV exposure of the human skin. Especially at times of the day or year with low solar elevations the UV exposure of parts of the human skin can be many times higher than that of the horizontal surface. Examples of three-dimensional modelling of the human UV irradiation are shown for different times of the day and year, altitudes above sea level, body postures and genders. In these examples the UV "hotspots" can be detected and, among other things, used to inform and educate the public about UV radiation.