Science.gov

Sample records for 10be exposure age

  1. In situ 10Be-26Al exposure ages at Meteor Crater, Arizona

    USGS Publications Warehouse

    Nishiizumi, K.; Kohl, C.P.; Shoemaker, E.M.; Arnold, J.R.; Klein, J.; Fink, D.; Middleton, R.

    1991-01-01

    A new method of dating the surface exposure of rocks from in situ production of 10Be and 26Al has been applied to determine the age of Meteor Crater, Arizona. A lower bound on the crater age of 49,200 ?? 1,700 years has been obtained by this method. ?? 1991.

  2. 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

  3. Cosmogenic 10Be Exposure Age for the Cut Bank Creek terminal moraine, Glacier National Park, MT

    NASA Astrophysics Data System (ADS)

    Quirk, B.; Laabs, B. J.; Leonard, E. M.; Caffee, M. W.

    2012-12-01

    Mountain glaciers are highly sensitive to temperature and precipitation with geologic records that are superb proxies of climate change. In the Rocky Mountains of the western United States, abundant records of Late Pleistocene glaciation provide an opportunity for understanding paleoclimate throughout this region, especially in places where the chronology of glaciation is precisely known. Cosmogenic 10Be exposure dating has been widely applied to glacial deposits in the Rocky Mountains, providing precise numerical ages and improving the understanding of glacial chronologies in this region. Despite these improvements, the chronology of the last Pleistocene glaciation of the northernmost Rocky Mountains is not completely understood. Cosmogenic 10Be exposure dating was applied to the Cut Bank Creek valley in the Lewis Range of the Northern Rocky Mountains, where a discrete mountain glacier deposited a broad terminal moraine during the last Pleistocene glaciation. Exposure ages of eight quartzite and sandstone boulders at the crest of the ice-distal sector of the terminal moraine indicate that abandonment occurred at 15.6 ± 0.8 ka. This age is consistent with age limits of several terminal moraines elsewhere in the Northern Rocky Mountains, suggesting that the last Pleistocene glaciation culminated in this region after the global Last Glacial Maximum.

  4. 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

  5. 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.

  6. Examination of surface exposure age of Antarctic moraines using in situ produced [sup 10]Be and [sup 26]Al

    SciTech Connect

    Brown, E.T.; Edmond, J.M. ); Raisbeck, G.M.; Yiou, F. ); Kurz, M.D.; Brook, E.J. )

    1991-08-01

    Concentrations of [sup 10]Be (t[sub 1/2] = 1.5 [times] 10[sup 6]y) and [sup 26]Al (t[sub 1/2] = 0.72 [times] 10[sup 6]y) have been determined by accelerator mass spectrometry (AMS) in a suite of quartz samples taken from sandstone boulders in several moraines in Arena Valley, a dry valley adjacent to the Taylor Glacier in the Quatermain Mountains, Southern Victoria Land, East Antarctica. These isotopes are produced in surficial quartz by cosmic ray spallation of O and Si. The concentrations in these samples ranged from 6.1 [times] 10[sup 5] to 3.0 [times] 10[sup 7] at g[sup [minus]1] for [sup 10]Be and from 9.4 [times] 10[sup 6] to 1.2 [times] 10[sup 8] at g[sup [minus]1] for [sup 26]Al, depending upon the extent of exposure at the surface. Production rates of 17[sub [minus]4][sup +16] at g[sup [minus]1]y[sup [minus]1] for [sup 10]Be and 113[sub [minus]16][sup +54] at g[sup [minus]1]y[sup [minus]1] for [sup 26]Al at 1300 m and 87[degree]S and a [sup 26]Al:[sup 10]Be production ratio of 6.5[sub [minus]1.3][sup +1.3] were calculated from the data. These values correspond to sea-level production rates at high geomagnetic latitude of 6.4 at g[sup [minus]1]y[sup [minus]1] and 41.7 at g[sup [minus]1]y[sup [minus]1] for [sup 10]Be and [sup 26]Al, respectively, consistent with determinations based on [approximately]11 Ky glacially polished surfaces in the Sierra Nevada in California. These production rates imply exposure ages for the various moraines ranging from 50 Ky to 2.5 My, in accordance with other geological evidence. The [sup 10]Be and [sup 26]Al ages of these rocks compare favorably with those found using a similar dating method based on in situ production of [sup 3]He.

  7. 10Be exposure age chronology of the last glaciation in the Krkonoše Mountains, Central Europe

    NASA Astrophysics Data System (ADS)

    Engel, Zbyněk; Braucher, Régis; Traczyk, Andrzej; Laetitia, Léanni; AsterTeam

    2014-02-01

    A new chronology of the last glaciation is established for the Krkonoše (Giant) Mountains, Central Europe, based on in-situ produced 10Be in moraine boulders. Exposure ages and Schmidt Hammer rebound values obtained for terminal moraines on the northern and southern flank of the mountains suggest that the oldest preserved moraines represent early phases of the Last Glacial Maximum (LGM). Large moraines at the outlet of the Snowy Cirques (Śnieżne Kotły) and in the middle part of the Úpa (Obří důl) trough were deposited around 21 ka while a series of smaller moraines above the LGM deposits represent readvances that occurred no later than 18.1 ± 0.6 ka, 15.7 ± 0.5 ka, 13.5 ± 0.5 ka and 12.9 ± 0.7 ka. An exposure age of 13.8 ± 0.4 ka obtained for protalus ramparts at the foot of the Úpská jáma Cirque headwall indicates that glaciers advanced only in north- to east-facing cirques during the Lateglacial. The last glacier fluctuation was synchronous with the Younger Dryas cold event. The timing of local glacier advances during the last glacial episode correlates with the late Weichselian glacier phases in the Alps and in the Bavarian/Bohemian Forest.

  8. 10Be surface exposure ages on the late-Pleistocene and Holocene history of Linnébreen on Svalbard

    NASA Astrophysics Data System (ADS)

    Reusche, Melissa; Winsor, Kelsey; Carlson, Anders E.; Marcott, Shaun A.; Rood, Dylan H.; Novak, Anthony; Roof, Steven; Retelle, Michael; Werner, Alan; Caffee, Marc; Clark, Peter U.

    2014-04-01

    Arctic glaciers were sensitive to past changes in high-latitude winter precipitation and summer temperature. Here we develop a late-Pleistocene to Holocene history for Linnébreen (Linné Glacier) in western Svalbard using 10Be surface exposure ages on isolated erratic and moraine boulders. We show that Linnébreen had separated from the larger ice sheet over Svalbard and was retreating up valley around the start of the Younger Dryas cold period. We attribute this retreat during a cold period on Svalbard to moisture starvation of Linnébreen from advanced sea ice and/or elevated shortwave boreal summer insolation that overwhelmed any reduction in sensible heat. After an ice-free period during the early to middle Holocene, Linnébreen reformed sometime after 4.6 ± 0.2 ka, and was at a position roughly equivalent to its Little Ice Age (LIA) maximum extent before it began to retreat at 1.6 ± 0.2 ka. Comparison with calibrated 14C dates from three other glaciers could suggest that this period of ice retreat at ˜1.6 ka could be regional in extent. Linnébreen occupied the pre-LIA moraine when there was an increased ratio of cold Arctic-sourced relative to warm Atlantic-sourced waters around Svalbard and advanced sea ice. The retreat of Linnébreen at ˜1.6 ka was concurrent with the increased presence of warm Atlantic waters around Svalbard and attendant sea-ice retreat. These coincident changes in ocean temperatures, sea-ice extent, and Linnébreen moraine age could imply a climatic forcing of the pre-LIA advance and retreat of Linnébreen. Summer temperatures, rather than changes in precipitation, would then be dominant in driving ice retreat, although the possibility of stochastic glacier-margin variability cannot be excluded. Our data therefore suggest that Linnébreen may have responded differently to past changes in sea-ice extent that could depend on the background climate state (deglacial climate vs. late-Holocene climate), which highlights the complexity in

  9. Recent Contractile Deformation in the Forearc of Southern Peru: A Geomorphologic Analysis And 10Be Surface Exposure Ages

    NASA Astrophysics Data System (ADS)

    Hall, S.; Farber, D. L.; Audin, L.; Finkel, R.

    2007-12-01

    . Cosmogenic 10Be surface exposure ages from a set of three distinct abandoned terraces in the Pampa Cabeza de Vaca region yield ages ranging from ~35-550ky and incision rates of ~0.04-0.09mm/yr. Thus, the contractile deformation within this region has been active for at least the last 500ky and is plausibly presently active. The documentation of recent contractile deformation within the forearc of southern Peru stylistically contrasts with previously held view active deformation in this region is dominated by extensional topographic collapse. Moreover, active shortening within the Peruvian forearc bears on our models of how the Altiplano plateau is currently being maintained along the western margin. Indeed, by identifying and quantifying active deformation within the Peruvian forearc, we can begin to address the potential links between surface processes related to climate and active tectonics, and the dynamics of the lithosphere.

  10. Recent Contractile Deformation in the Forearc of Southern Peru: A Geomorphologic Analysis And 10Be Surface Exposure Ages

    NASA Astrophysics Data System (ADS)

    Hall, S.; Farber, D. L.; Audin, L.; Finkel, R.

    2004-12-01

    . Cosmogenic 10Be surface exposure ages from a set of three distinct abandoned terraces in the Pampa Cabeza de Vaca region yield ages ranging from ~35-550ky and incision rates of ~0.04-0.09mm/yr. Thus, the contractile deformation within this region has been active for at least the last 500ky and is plausibly presently active. The documentation of recent contractile deformation within the forearc of southern Peru stylistically contrasts with previously held view active deformation in this region is dominated by extensional topographic collapse. Moreover, active shortening within the Peruvian forearc bears on our models of how the Altiplano plateau is currently being maintained along the western margin. Indeed, by identifying and quantifying active deformation within the Peruvian forearc, we can begin to address the potential links between surface processes related to climate and active tectonics, and the dynamics of the lithosphere.

  11. 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

  12. Preliminary Vertical Slip Rate for the West Tahoe Fault from six new Cosmogenic 10Be Exposure Ages of Late Pleistocene Glacial Moraines at Cascade Lake, Lake Tahoe, California

    NASA Astrophysics Data System (ADS)

    Pierce, I. K. D.; Wesnousky, S. G.; Kent, G. M.; Owen, L. A.

    2015-12-01

    The West Tahoe Fault is the primary range bounding fault of the Sierra Nevada at the latitude of Lake Tahoe. It is a N-NW striking, east dipping normal fault that has a pronounced onshore quaternary scarp extending from highway 50 southwest of Meyers, CA to Emerald Bay. At Cascade Lake, the fault cuts and progressively offsets late Pleistocene right lateral moraines. The fault vertically offsets the previously mapped Tahoe moraine ~83 m and the Tioga moraine ~23 m, measured from lidar data. Seventeen samples were collected for 10Be cosmogenic age analysis from boulders on both the hanging and footwalls of the fault along the crests of these moraines.We report here the initial analysis of 6 of these boulders and currently await processing of the remainder. The 10Be exposure ages of 3 boulders each on the younger Tioga and older Tahoe moraines range from 12.7 +/- 1.6 to 20.7 +/- 3.3 ka and 13.3 +/- 2.1 to 72.5 +/- 8.8 ka, respectively. Using the oldest ages as minima, these preliminary results suggest that the slip rate has averaged ~1 mm/yr since the penultimate glaciation, in accord with estimates of previous workers, and place additional bounds on the age of glaciation in the Lake Tahoe basin. The Last Glacial Maxima and penultimate glaciation near Lake Tahoe thus appear to coincide with the Tioga and Tahoe II glaciations of the Eastern Sierra.

  13. Cosmogenic 10Be and 26Al exposure ages of glaciations in the Frankland Range, southwest Tasmania reveal a limited MIS-2 ice advance

    NASA Astrophysics Data System (ADS)

    Kiernan, Kevin; Fink, David; McConnell, Anne

    2017-02-01

    New mapping of the glacial geomorphology coupled with 10Be and 26Al exposure age dating of moraines on the flanks of the Frankland Range in south west Tasmania indicate that glacier extent during MIS-2 was far smaller than during earlier glaciations with the ice cover being confined to only the uppermost cirques of the range. Moraines further down the range flanks, ∼50-150 m lower in altitude than the MIS-2 dated advance, indicate that glaciers were only slightly larger during earlier glaciations and, depending on the interpretation of their exposure ages, may range from MIS 7 to MIS 12. These older moraines are nested inside the maximum ice limits of an even more ancient and extensive glaciation, defined by degraded valley floor moraines and coalescing glacio-fluvial fans that remain undated but appear no younger than MIS 12. Patterns of glacial erosion and moraine deposition on the Frankland Range suggest that the more recent glaciations were increasingly influenced by the erosional morphology initiated by earlier glaciers. Microclimatic differences resulting from this earlier glacial topography were particularly influential determinants of glaciation during MIS 2. These results are consistent with emerging evidence from studies of other ranges in southwest Tasmania.

  14. Deglaciation of Antarctica since the Last Glacial Maximum - what can we learn from cosmogenic 10Be and 26Al exposure ages?

    NASA Astrophysics Data System (ADS)

    Fink, David

    2015-04-01

    Ice volume changes at the coastal margins of Antarctica during the global LGM are uncertain. The little evidence available suggests that behaviour of the East and West Antarctic Ice Sheets are markedly different and complex. It is hypothesised that during interglacials, thinning of the Ross Ice Shelf, a more open-water environment and increased precipitation, allowed outlet glaciers draining the Transantarctic Mnts and fed by interior Ice Sheets to advance during moist warmer periods, out of phase with colder arid periods. In contrast, glacier dynamics along the vast coastal perimeter of East Antarctica is strongly influenced by Southern Ocean conditions. Cosmogenic 10Be and 26Al chronologies, although restricted to ice-free oasis and mountains flanking drainage glaciers, has become an invaluable, if not unique, tool to quantify spatial and temporal Pleistocene ice sheet variability over the past 2 Ma. Despite an increasing number of well documented areas, extracting reliable ages from glacial deposits in polar regions is problematic. Recycling of previously exposed/ buried debris and continual post-depositional modification leads to age ambiguities for a coeval glacial landform. More importantly, passage of cold-based ice can leave a landform unmodified resulting in young erratics deposited on ancient bedrock. Advances in delivering in-situ radiocarbon to routine application offer some relief. Exposure ages from different localities throughout East Antarctica (Framnes Mnts, Lutzow-Holm Bay, Vestfold Hills) and West Antarctica (Denton Ranges, Hatherton Glacier, Shackleton Range) highlight some of the new findings. This talk presents results which quantify the magnitude and timing of paleo-ice sheet thickness changes, questions the validity of an Antarctic LGM and discusses the complexities encountered in the often excessive spread in exposure ages.

  15. The Lesser Himalaya stripped naked: tecto-climatic induced fluvial response during the Quaternary inferred from in situ 10Be exposure ages

    NASA Astrophysics Data System (ADS)

    Swander, Z.; Dosseto, A.; Fink, D.; Mifsud, C.

    2011-12-01

    Deciphering a catchment's response to climatic and tectonic forcings requires a spatially extensive geochronology of aggradation-degradation. The Alaknanda River, a major tributary of the Ganga River, constitutes an ideal area for studying this question. From its glacial headwaters sourcing sediment from 7,000+ meter peaks, fueled by glacial meltwater and the Indian Summer Monsoon (ISM) that annually brings the river to sustained flood levels; the Alaknanda River transports a tremendous volume of sediment to the fertile floodplain and delta of the Ganga River. Seven study sites lie within a 200km tectonically active stretch of the river valley transecting the Lesser Himalayan lithological units; demarcated by the Main Central and Main Boundary Thrusts. Twenty bedrock strath surface exposure ages, spreading over two orders of magnitude (102-104 years), were established by measuring the cosmogenic radionuclide (CRN) concentration of beryllium-10. A majority of the bedrock exposure ages support a prior hypothesis for climate driven onset of early-mid Holocene erosion, which resulted in the cessation of catchment-wide fluvial aggradation period at 8ka (Juyal et al. 2010) and culminated with renewed incision of underlying bedrock. Incision rates have a narrow range of 3-7 mm×yr-1 suggesting spatial uniformity, and agree largely with previous estimates (4 mm×yr-1; Barnard et al. 2001).

    When comparing the Holocene aggradation-degradation transition to paleoclimate records from the Guliya Ice Core (Thompson et al. 1997), an apparent correlation exists with the waxing and waning of the ISM as postulated by Juyal et al. (2010). However, preceding the Last Glacial Maximum, a sustained decline in the ISM strength coincided with both periods of active alluvial deposition and erosion. Two episodes of valley wide aggradation occur during extensive regional glaciation 49-25ka, and

  16. Cosmogenic 10Be constraints on Little Ice Age glacial advances in the eastern Tian Shan, China

    NASA Astrophysics Data System (ADS)

    Li, Yanan; Li, Yingkui; Harbor, Jon; Liu, Gengnian; Yi, Chaolu; Caffee, Marc W.

    2016-04-01

    Presumed Little Ice Age (LIA) glacial advances, represented by a set of fresh, sharp-crested, boulder covered and compact moraines a few hundred meters downstream from modern glaciers, have been widely recognized in the Central Asian highlands. However, few studies have constrained the formation ages of these moraines. We report 31 10Be exposure ages from presumed LIA moraines in six glacial valleys in the Urumqi River headwater area and the Haxilegen Pass area of the eastern Tian Shan, China. Our results reveal that the maximum LIA glacial extent occurred mainly around 430 ± 100 yr, a cold and wet period as indicated by proxy data from ice cores, tree rings, and lake sediments in Central Asia. We also dated a later glacial advance to 270 ± 55 yr. However, 10Be exposure ages on several presumed LIA moraines in front of small, thin glaciers are widely scattered and much older than the globally recognized timing of the LIA. Historical topographic maps indicate that most glaciers were more extensive in the early 1960s, and two of our 10Be sample sites were located close to the ice front at that time. Boulders transported by these small and thin glaciers may be reworked from deposits originally formed prior to the LIA glacial advances, producing apparently old and widely scattered exposure ages due to varied nuclide inheritance. Other published ages indicated an earlier LIA advance around 790 ± 300 yr in the easternmost Tian Shan, but in our study area the more extensive advance around 430 ± 100 yr likely reworked or covered deposits from this earlier event.

  17. Deglaciation and landscape history around Annapurna, Nepal, based on 10Be surface exposure dating

    NASA Astrophysics Data System (ADS)

    Zech, Roland; Zech, Michael; Kubik, Peter W.; Kharki, Krishna; Zech, Wolfgang

    2009-06-01

    The High Himalaya is a key area for tectonic, geomorphological and climate studies, because of its extreme relief and location at the transition zone between areas with abundant monsoonal precipitation and the arid/semiarid Tibetan Plateau. We present 10Be surface exposure ages on 22 boulders from the Annapurna area in Nepal. The ages improve understanding of the Late Quaternary landscape history and the geomorphological processes operating in this part of the Himalaya. Although our study is reconnaissance in nature, it highlights the importance of catastrophic events, such as landslides and debris flows, for denudation of high mountains. Holocene exposure ages for the Dhampu-Chooya landslide (˜4.1 ± 0.6 ka) and for 600 m of alluviation in Kali Gandaki Valley (˜2.1 ± 0.6 ka), for example, indicate the frequent occurrence and extent of catastrophic events and their implications for natural hazards. We also offer an explanation for the differences in Late Quaternary glacial chronologies at closely spaced study sites in the Nepal Himalaya. Topographically controlled and spatially variable precipitation in the Himalaya determines the sensitivity of glaciers to changes in temperature and precipitation. Accordingly, some glaciers advanced in-phase with Northern Hemisphere ice sheets, whereas others reached their maximum extent at times of increased monsoonal precipitation during Marine Isotope Stage 3 and the early Holocene.

  18. Advances in cosmogenic surface exposure dating: Using combined in situ 14C-10Be analysis for deglaciation scenarios

    NASA Astrophysics Data System (ADS)

    Hippe, Kristina; Ivy-Ochs, Susan; Kober, Florian; Christl, Marcus; Fogwill, Christopher; Turney, Chris; Rood, Dylan; Lupker, Maarten; Schlücher, Christian; Wieler, Rainer

    2016-04-01

    Cosmogenic nuclides are routinely used to investigate deglaciation histories by exposure dating of rock surfaces after glacier retreat. For bedrock surfaces that have been efficiently eroded by glacier ice, the most commonly applied cosmogenic 10Be isotope has proven to give reliable estimates of the integrated time of surface exposure since major ice decay. Due to its long half-life (~1.4 Ma), however, 10Be does not record short episodes of intermittent surface cover, e.g. during phases of glacier readvance, which might have interrupted the general deglaciation trend. To detect such cases of "complex exposure", 10Be-based dating can be combined with the analysis of the short-lived (5730 a) in situ cosmogenic 14C nuclide. We present two examples, in which combined in situ 14C-10Be analysis has been successfully applied to reconstruct in detail post-LGM surface exposures histories - in the Swiss Alps [1] and in Antarctica [2]. In a study on the Gotthard Pass, Central Swiss Alps, in situ 14C-10Be exposure dating was combined with extensive mapping of glacial erosional features. Data from both cosmogenic nuclides are in overall good agreement with each other confirming continuous exposure of the Gotthard Pass area throughout the Holocene. Some slightly younger in situ 14C ages compared to the corresponding 10Be ages are interpreted to result from partial surface shielding due to snow cover. Constraining the average Holocene snow depth from the in situ 14C data allowed to apply an appropriate snow shielding correction for the 10Be exposure ages. Integration of the snow-corrected exposure ages with field observations provided a detailed chronology of a progressive downwasting of ice from the maximum LGM ice volume with a gradual reorganization of the ice flow pattern and a southward migration of the ice divide. In a study on the evolution and reorganization of ice streams entering the Weddell Sea, Antarctica, during the last deglaciation, ice sheet modelling was

  19. 10Be surface exposure dating of rock glaciers in Larstigtal, Tyrol, Austria

    NASA Astrophysics Data System (ADS)

    Ivy-Ochs, S.; Kerschner, H.; Maisch, M.; Christl, M.; Kubik, P. W.; Schluchter, C.

    2009-04-01

    In the context of Lateglacial and Holocene climate change research, rock glaciers (creeping mountain permafrost) also play an important role. They are phenomena of discontinuous alpine permafrost and as such good indicators for the mean annual air temperature for the period they are active. We have 10Be surface exposure dated boulders from two relict rock glaciers in Larstigtal, Austria. This is the type area for a postulated mid-Holocene cold period called the Larstig oscillation. The period of activity was suggested to be of similar age as the mid-Holocene Frosnitz advance of glaciers in the Venediger Mountains farther to the east (Patzelt and Bortenschlager, 1973). For rock glaciers of this size to be active at 2200 m a.s.l. in Larstig valley would have required a significant drop in temperatures, thus a marked mid-Holocene cold pulse, for at least several centuries at around 7.0 ka. In contrast, our exposure dates show that the rock glaciers stabilized during the early Preboreal (Ivy-Ochs et al., submitted). We see no distinct pattern with respect to exposure age and boulder location on the rock glaciers. This implies that for our site the blocks did not acquire inherited 10Be during exposure in the free rock face, in the talus at the base of the slope, or during transport on the rock glaciers. Our data point to final stabilization of the Larstigtal rock glaciers in the earliest Holocene and not in the middle Holocene. Combined with data from other archives (Nicolussi et al., 2005), there appears to have been no time window in the middle Holocene long enough for rock glaciers of the size and at the elevation of the Larstig site to have formed. Ivy-Ochs, S., Kerschner, H., Maisch, M., Christl, M., Kubik, P.W., Schlüchter, C., Latest Pleistocene and Holocene glacier variations in the European Alps. Quaternary Science Reviews (submitted). Nicolussi, K., Kaufmann, M., Patzelt, G., van der Plicht, J., Thurner, A., 2005. Holocene tree-line variability in the Kauner

  20. 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

  1. Rapid thinning of the Welsh Ice Cap at 20-19 ka based on 10Be ages

    NASA Astrophysics Data System (ADS)

    Hughes, Philip D.; Glasser, Neil F.; Fink, David

    2016-01-01

    New 10Be ages from the summits of three mountain areas of North Wales reveal a very similar exposure timing as the Welsh Ice Cap thinned after the global Last Glacial Maximum. Eight bedrock and one boulder sample gave a combined arithmetic mean exposure age of 19.08 ± 0.80 ka (4.2%, 1σ). Similar exposure ages over a 320 m vertical range (824 to 581 m altitude) show that ice cap thinning was very rapid and spatially uniform. Using the same production rate and scaling scheme, we recalculated six published 10Be exposure ages from the nearby Arans, which also covered a similar elevation range from 608 to 901 m and obtained an arithmetic mean of 19.41 ± 1.45 ka (7.5%, 1σ). The average exposure age of all 15 accepted deglaciation ages is 19.21 ± 1.07 (5.6%, 1σ). The complete dataset from North Wales provides very strong evidence indicating that these summits became exposed as nunataks at 20-19 ka. This result provides important insight to the magnitude of ice surface lowering and behavior of the Welsh Ice Cap during the last deglaciation that can be compared to other ice masses that made up the British-Irish Ice Sheet.

  2. Particle trajectories on hillslopes: Implications for particle age and 10Be structure

    NASA Astrophysics Data System (ADS)

    Anderson, Robert S.

    2015-09-01

    Many geomorphic systems act as conveyor belts onto which material is loaded at a particular rate and is transported in one direction toward another system that serves as a sink. As the material travels, it ages, it changes in grain size, it accumulates cosmogenic radionuclides, it adsorbs or releases nutrients, and it weathers. Here I address the hillslope conveyor. As many geochemical processes are depth-dependent, the depth history of a particle becomes important to know. I calculate soil particle trajectories in the horizontal-depth plane and address three cases, one in which horizontal speeds decline exponentially with depth, a second in which they are uniform with depth, and a third in which horizontal speeds are also uniform but all profile values are vertically well-mixed. Vertical speeds are governed by continuity in an incompressible medium and by the boundary condition of zero vertical particle speed at the soil surface. Particle trajectories must therefore become surface parallel at the surface. Knowledge of soil particle trajectories allows calculation of residence times and concentration profiles of 10Be in the soil. The results inform strategies for interpretation of nuclide concentrations in soils and stream sediments and for inference of transport rate profiles. In all steady cases, the particle age and 10Be structure are uniform with distance from the divide. When significant vertical gradients in horizontal speed occur, the patterns of particle age and of 10Be concentration are dominated by the depth scale of the transport process. In unmixed cases, the particle age and 10Be concentration in near-surface samples can greatly exceed the vertically averaged values, reflecting the fact that the vertical speeds of particles slow dramatically as they near the surface. In cases in which horizontal speed varies significantly with depth, the vertically averaged concentration of 10Be within the soil can significantly underpredict the mean 10Be concentration

  3. Timing of terminal Pleistocene deglaciation at high elevations in southern and central British Columbia constrained by 10Be exposure dating

    NASA Astrophysics Data System (ADS)

    Margold, Martin; Stroeven, Arjen P.; Clague, John J.; Heyman, Jakob

    2014-09-01

    The Cordilleran Ice Sheet (CIS) covered most of British Columbia and southern Yukon Territory at the local Last Glacial Maximum (lLGM) during Marine Oxygen Isotope Stage 2. However, its subsequent demise is not well understood, particularly at high elevations east of its ocean-terminating margin. We present 10Be exposure ages from two high-elevation sites in southern and central British Columbia that help constrain the time of initial deglaciation at these sites. We sampled granodiorite erratics at elevations of 2126-2230 m a.s.l. in the Marble Range and 1608-1785 m a.s.l. in the Telkwa Range at the western margin of the Interior Plateau. The erratics at both sites are near ice-marginal meltwater channels that delineate the local ice surface slope and thus the configuration of the ice sheet during deglaciation. The locations of the erratics and their relations to meltwater channels ensure that the resulting 10Be ages date CIS deglaciation and not the retreat of local montane glaciers. Our sample sites emerged above the surface of the CIS as its divide migrated westward from the Interior Plateau to the axis of the Coast Mountains. Two of the four samples from the summit area of the Marble Range yielded apparent exposure ages of 14.0 ± 0.7 and 15.2 ± 0.8 ka. These ages are 1.8-3.0 ka younger than the well-established lLGM age of ca 17 ka for the Puget lobe of the CIS in Washington State; they are 1.7 ka younger than the lLGM age for the Puget lobe if a snow-shielding correction to their uncertainty-weighted mean age is applied. The other two samples yielded much older apparent exposure ages (20.6 ± 1.4 and 33.0 ± 1.5 ka), indicating the presence of inherited isotopes. Four samples collected from the summit area of the Telkwa Range in the Hazelton Mountains yielded well clustered apparent exposure ages of 10.1 ± 0.6, 10.2 ± 0.7, 10.4 ± 0.5, and 11.5 ± 1.1 ka. Significant present-day snow cover introduces a large uncertainty in the apparent exposure ages from

  4. Age of Zhoukoudian Homo erectus determined with (26)Al/(10)Be burial dating.

    PubMed

    Shen, Guanjun; Gao, Xing; Gao, Bin; Granger, Darryl E

    2009-03-12

    The age of Zhoukoudian Homo erectus, commonly known as 'Peking Man', has long been pursued, but has remained problematic owing to the lack of suitable dating methods. Here we report cosmogenic (26)Al/(10)Be burial dating of quartz sediments and artefacts from the lower strata of Locality 1 in the southwestern suburb of Beijing, China, where early representatives of Zhoukoudian Homo erectus were discovered. This study marks the first radioisotopic dating of any early hominin site in China beyond the range of mass spectrometric U-series dating. The weighted mean of six meaningful age measurements, 0.77 +/- 0.08 million years (Myr, mean +/- s.e.m.), provides the best age estimate for lower cultural layers 7-10. Together with previously reported U-series dating of speleothem calcite and palaeomagnetic stratigraphy, as well as sedimentological considerations, these layers may be further correlated to S6-S7 in Chinese loess stratigraphy or marine isotope stages (MIS) 17-19, in the range of approximately 0.68 to 0.78 Myr ago. These ages are substantially older than previously supposed and may imply early hominin's presence at the site in northern China through a relatively mild glacial period corresponding to MIS 18.

  5. Understanding complex exposure history of Mount Hampton, West Antarctica using cosmogenic 3He, 21Ne and 10Be in olivine

    NASA Astrophysics Data System (ADS)

    Carracedo, Ana; Rodes, Angel; Stuart, Finlay; Smellie, John

    2016-04-01

    Combining stable and radioactive cosmogenic nuclides is an established tool for revealing the complexities of long-term landscape development. To date most studies have concentrated on 21Ne and 10Be in quartz. We have combined different chemical protocols for extraction of cosmogenic 10Be from olivine, and measured concentrations in olivine from lherzolite xenoliths from the peak of Mount Hampton (~3,200 m), an 11 Ma shield volcano on the West Antarctic rift flank. We combine this data with cosmogenic 3He (and 21Ne) in the olivines in order to unravel the long-term environmental history of the region. The mean 3He/21Ne ratio (1.98 ± 0.22) is consistent with the theoretical value and previous determinations. 10Be/3He ratios (0.012 to 0.018) are significantly lower than the instantaneous production ratio (~0.045). The data are consistent with 1-3 Ma of burial. The altitude of the volcano rules out over-topping of the peak by the West Antarctic Ice Sheet only possible burial could be generated by the growth of an ice cap although this contradicts the absence of evidence for ice cover. The 3He-10Be data can also be generated during episodic erosion of the volcanic ash over the last few million years. The data requires a minimum depth of 1 to 2.5 m for the samples during a minimum age of 5 Ma and maximum long-term erosion rate of ~0.5 m/Ma with at least one erosive episode reflecting short-term erosion rate of ~7 m/Ma that would have brought the samples into the surface during the last ~350 ka. Erosion in this type of landscape could be related to interglacial periods where cryostatic erosion can occur generating an increase in the erosion rate. This study shows that episodic erosion can produce stable-radioactive cosmogenic isotope systematics that are similar to those generated by exposure-burial cycles.

  6. The deep accumulation of 10Be at Utsira, southwestern Norway: Implications for cosmogenic nuclide exposure dating in peripheral ice sheet landscapes

    NASA Astrophysics Data System (ADS)

    Briner, Jason P.; Goehring, Brent M.; Mangerud, Jan; Svendsen, John Inge

    2016-09-01

    Cosmogenic nuclide exposure dating is a widely used method for constraining past ice sheet histories. We scrutinize a recently published data set of cosmogenic 10Be data from erratic boulders in Norway used to constrain the deglaciation of the western Scandinavian Ice Sheet to 20 ka. Our model of the 10Be inventory in glacial surfaces leads us to conclude that the chronology may be afflicted by the deep subsurface accumulation of 10Be during long-lasting ice-free periods that resulted in 10Be ages >10% too old. We suggest that the majority of the dated erratic boulders contain a uniform level of inherited muon-produced 10Be and were derived from bedrock depths >2.5 m and most likely ~4 m. The implication of our finding is that for landscapes that experience long ice-free periods between brief maximum glacial phases, glacial erosion of >5 m is required to remove detectable traces of inherited 10Be.

  7. 10Be dating reveals early-middle Holocene age of the Drygalski Moraines in central West Greenland

    NASA Astrophysics Data System (ADS)

    Cronauer, Sandra L.; Briner, Jason P.; Kelley, Samuel E.; Zimmerman, Susan R. H.; Morlighem, Mathieu

    2016-09-01

    We reconstruct the history of the Greenland Ice Sheet margin on the Nuussuaq Peninsula in central West Greenland through the Holocene using lake sediment analysis and cosmogenic 10Be exposure dating of the prominent Drygalski Moraines. Erratics perched on bedrock outboard of the Drygalski Moraines constrain local deglaciation to ∼9.9 ± 0.6 ka (n = 2). Three Drygalski Moraine crests yield mean 10Be ages of 8.6 ± 0.4 ka (n = 2), 8.5 ± 0.2 ka (n = 3), and 7.6 ± 0.1 ka (n = 2) from outer to inner. Perched erratics between the inner two moraines average 7.8 ± 0.1 ka (n = 2) and are consistent with the moraine ages. Sediments from a proglacial lake with a catchment area extending an estimated 2 km beneath (inland of) the present ice sheet terminus constrain an ice sheet minimum extent from 5.4 ka to 0.6 ka. The moraine chronology paired with the lake sediment stratigraphy reveals that the ice margin likely remained within ∼2 km of its present position from ∼9.9 to 5.4 ka. This unexpected early Holocene stability, preceded by rapid ice retreat and followed by minimum ice extent between ∼5.4 and 0.6 ka, contrasts with many records of early Holocene warmth and the Northern Hemisphere summer insolation maximum. We suggest ice margin stability may instead be tied to adjacent ocean temperatures, which reached an optimum in the middle Holocene.

  8. Beryllium geochemistry in soils: Evaluation of 10Be/9Be ratios in authigenic minerals as a basis for age models

    USGS Publications Warehouse

    Barg, E.; Lal, D.; Pavich, M.J.; Caffee, M.W.; Southon, J.R.

    1997-01-01

    Soils contain a diverse and complex set of chemicals and minerals. Being an 'open system', both in the chemical and nuclear sense, soils have defied quantitative nuclear dating. However, based on the published studies of the cosmogenic atmospheric 10Be in soils, its relatively long half-life (1.5 Ma), and the fact that 10Be gets quickly incorporated in most soil minerals, this radionuclide appears to be potentially the most useful for soil dating. We therefore studied the natural variations in the specific activities of 10Be with respect to the isotope 9Be in mineral phases in eight profiles of diverse soils from temperate to tropical climatic regimes and evaluated the implications of the data for determining the time of formation of soil minerals, following an earlier suggestion [Lal et al., 1991. Development of cosmogenic nuclear methods for the study of soil erosion and formation rates. Current Sci. 61, 636-639.]. We find that the 10Be/9Be ratios in both bulk soils and in the authigenic mineral phases are confined within a narrower range than in 10Be concentrations. Also, the highest 10Be/9Be ratios in authigenic minerals are observed at the soil-rock interface as predicted by the model. We present model 10Be/9Be ages of the B-horizon and the corresponding soil formation rates for several soil profiles. The present study demonstrates that the 10Be/9Be ratios in the authigenic phases, e.g. clay and Fe-hydroxides, can indeed be used for obtaining useful model ages for soils younger than 10-15 Ma. However, the present work has to be pushed considerably further, to take into account more realistic age models in which, for instance, downward transport of 10Be and clays, and in-situ dissolution of clay minerals at depths, altering the 10Be/9Be ratios of the acidic solutions, are included. We show that in the case of younger soils (< 1 Ma) studied here, their 10Be inventories and 10Be/9Be ratios have been significantly disturbed possibly by mixing with transported

  9. Mid-late Pleistocene glacial evolution in the Grove Mountains, East Antarctica, constraints from cosmogenic 10Be surface exposure dating of glacial erratic cobbles

    NASA Astrophysics Data System (ADS)

    Dong, Guocheng; Huang, Feixin; Yi, Chaolu; Liu, Xiaohan; Zhou, Weijian; Caffee, Marc W.

    2016-08-01

    Glacial histories from the East Antarctic Ice Sheet (EAIS) provide keys to understanding correlations between the EAIS and global climate. They are especially helpful in the assessment of global sea level change, and as a means of quantifying the magnitude of past glacial activity and the rate at which ice responded to climate change. Given the significance of EAIS glacial histories, it is imperative that more glacial chronologic data for this region be obtained, especially for the mid-to-late Pleistocene. We report cosmogenic 10Be surface exposure dating results from glacially transported cobbles embedded in blue-ice moraine material at Mount Harding, the Grove Mountains, EAIS. Forty exotic cobbles sampled along two profiles (A and B) on this blue-ice moraine present apparent exposure-ages ranging from 7.2 to 542.2 ka. We explore this scattered dataset by using Principal Component Analysis (PCA) to identify statistically significant trends in the data. We identify a correlation between exposure-age and distance of the cobbles from Mount Harding. In profile A, cobbles further from Mount Harding yield older exposure-ages than those that are relatively close. In profile B, cobbles closer to Mount Harding are found to have relatively older exposure-ages. In term of glacial history we suggest that the direction of ice flow changed during the period from ∼60 to 200 ka, and that multiple glacial fluctuations occurred in the mid-late Pleistocene.

  10. 10Be ages of glacial and meltwater features northwest of Lake Superior: a chronology of Laurentide Ice sheet deglaciation and eastward flooding from Glacial Lake Agassiz

    NASA Astrophysics Data System (ADS)

    Kelly, M. A.; Fisher, T. G.; Lowell, T.; Barnett, P.; Schaefer, J. M.; Schwartz, R.

    2009-12-01

    Significant controversy exists as to the role of Laurentide Ice Sheet meltwater in causing the Younger Dryas cold event. Recently, Lowell et al. (2009) presented a radiocarbon chronology of Laurentide Ice Sheet deglaciation along a north-south transect located northwest of Lake Superior. These authors concluded that the presence of the Laurentide Ice Sheet precluded an eastward drainage of glacial Lake Agassiz until mid-Younger Dryas time. Here, we use 10Be surface exposure dating to examine the timing of the eastward drainage of Lake Agassiz. We present 10Be ages of moraines and erratic boulders in meltwater pathways along the same transect as Lowell et al. (2009), northwest of Lake Superior. In general, 10Be ages of glacial features are similar to, or slightly older than, basal radiocarbon ages of nearby lakes. Based on the 10Be chronology, deglaciation of the Laurentide Ice Sheet in this region occurred between ~13,000 and 10,000 yr BP. We also present the first direct ages of flood deposits in bedrock channels presumably associated with the eastern drainage of Lake Agassiz. Evidence for flooding includes extensive channels incised into bedrock and enormous bedforms located north of Lake Superior. 10Be ages of two flood deposits near the Roaring River and Mundell Lake yield mean 10Be ages of ~11,700 and 11,000 yr BP, respectively. These ages indicate that occupation of the channels postdates initiation of the Younger Dryas by more than 1,000 years and are in general agreement with a basal radiocarbon age from nearby Lower Vail Lake (Teller et al., 2005). Preliminary paleohydrological estimates based on bedform clast sizes and channel geometries are velocities and discharges of 2.8-19.8 ms-1 and 4,200-30,000 m3s-1 at the Roaring River location and 2.5-17.5 ms-1 and 49,000-349,000 m3s-1 at the Mundell Lake location.

  11. Surface exposure dating with cosmogenic 10Be of Late Holocene rock avalanches onto glaciers in the Mont Blanc massif, Italy

    NASA Astrophysics Data System (ADS)

    Deline, Philip; Akçar, Naki; Ivy-Ochs, Susan; Kubik, Peter W.

    2013-04-01

    ) travelled onto the Glacier de la Brenva in 1920 and 1997 AD and reached the valley floor. Historical, geomorphological evidence, radiocarbon dating and lichenometry suggest a high RA frequency during the Late Holocene. RAs as large as 20th Century RAs are dated to: shortly before 1767 AD; the 14th Century; the early Middles Ages; and (indirectly) around 2.5 ka BP. Surface exposure dating of 15 granite boulders in deposits lying outside the 1920 deposit and on the opposite side of the Val Veny confirm both the extension and the dating of the 14th Century and c. 2.5 ka BP RAs. As already underlined by Porter and Orombelli in the 1980s, the importance of large RAs has to be emphasised to help prevent major risk induced by this highly destructive process in highly anthropomorphic valleys. In this perspective, and even for the most recent period, the contribution of surface exposure dating to the geomorphological analysis of landslide/moraine complex is valuable - especially where landform assemblages are complex.

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

    SciTech Connect

    der Woerd, J v; Klinger, Y; Sieh, K; Tapponnier, P; Ryerson, F; M?riaux, A

    2006-01-13

    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 exposure 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.

  13. Cosmogenic 10Be ages from the Meirs and Garwood Valleys, Denton Hills, West Antarctica, suggest an absence in LGM Ice Sheet expansion.

    NASA Astrophysics Data System (ADS)

    Fink, David; Joy, Kurt; Storey, Bryan

    2014-05-01

    It has been hypothesised that during interglacials, thinning of the Ross Ice Shelf allowed a more open water environment with increased local precipitation. This resulted in outlet glaciers, which drain the Transantarctic Mountains and fed by the East Antarctic Ice Sheet, advancing during moist warmer periods, apparently out of phase with colder arid dry periods. Significantly the ice core record during these warm periods also shows increased accumulation continent wide The geomorphology of the Denton Hills in the Royal Society Range, West Antarctica, is a result of Miocene fluvial incision reworked by subsequent glacial advances throughout the Quaternary. The Garwood and Miers glacial valleys drain ice across the Denton Hills into the Shelf, and should thus show maximum extent during interstadials. To understand the chronology of late Quaternary glaciations, 15 granitic boulders from terminal moraines were sampled for 10Be and 26Al cosmogenic dating. Obtaining reliable exposure ages of erratics within moraines that represent timing of deposition (i.e. glacial advances) is problematic in polar regions, where glacial activity is principally controlled by ice sheet dynamics. Recycling of previously exposed debris, uncertainty in provenance of glacially transported boulders and a lack of a post-depositional hydrologic process to remove previously exposed material from a valley system, leads to ambiguities in multiple exposure ages from a single coeval glacial landform. More importantly, cold-based ice advance can leave a landform unmodified resulting in young erratics deposited on bedrock that shows weathering and/or inconsistent age-altitude relationships. Primarily, inheritance becomes a difficulty in qualifying exposure ages from polar regions. Preliminary results from the Garwood and Miers Valleys indicate that glaciers in the Denton Hills had begun to retreat from their last maximum positions no later than 23-37 ka, and thus the local last glacial maximum

  14. Surface exposure dating of Holocene basalt flows and cinder cones in the Kula volcanic field (western Turkey) using cosmogenic 3He and 10Be

    NASA Astrophysics Data System (ADS)

    Heineke, Caroline; Niedermann, Samuel; Hetzel, Ralf; Akal, Cüneyt

    2015-04-01

    The Kula volcanic field is the youngest volcanic province in western Anatolia and covers an area of about 600 km2 around the town Kula (Richardson-Bunbury, 1996). Its alkali basalts formed by melting of an isotopically depleted mantle in a region of long-lived continental extension and asthenospheric upwelling (Prelevic et al., 2012). Based on morphological criteria and 40Ar/39Ar dating, four phases of Quaternary activity have been distinguished in the Kula volcanic field (Richardson-Bunbury, 1996; Westaway et al., 2006). The youngest lava flows are thought to be Holocene in age, but so far only one sample from this group was dated by 40Ar/39Ar at 7±2 ka (Westaway et al., 2006). In this study, we analysed cosmogenic 3He in olivine phenocrysts from three basalt flows and one cinder cone to resolve the Holocene history of volcanic eruptions in more detail. In addition, we applied 10Be exposure dating to two quartz-bearing xenoliths found at the surface of one flow and at the top of one cinder cone. The exposure ages fall in the range between ~500 and ~3000 years, demonstrating that the youngest volcanic activity is Late Holocene in age and therefore distinctly younger than previously envisaged. Our results show that the Late Holocene lava flows are not coeval but formed over a period of a few thousand years. We conclude that surface exposure dating of very young volcanic rocks provides a powerful alternative to 40Ar/39Ar dating. References Prelevic, D., Akal, C. Foley, S.F., Romer, R.L., Stracke, A. and van den Bogaard, P. (2012). Ultrapotassic mafic rocks as geochemical proxies for post-collisional dynamics of orogenic lithospheric mantle: the case of southwestern Anatolia, Turkey. Journal of Petrology, 53, 1019-1055. Richardson-Bunbury, J.M. (1996). The Kula Volcanic Field, western Turkey: the development of a Holocene alkali basalt province and the adjacent normal-faulting graben. Geological Magazine, 133, 275-283. Westaway, R., Guillou, H., Yurtmen, S., Beck, A

  15. Toward a Master Chronology for Western Greenland's Fjord Stade Moraines: New 10Be Ages from the Søndre Isortoq Region

    NASA Astrophysics Data System (ADS)

    Lesnek, A.; Briner, J. P.; Schweinsberg, A.; Lifton, N. A.

    2015-12-01

    Reconstructions of Greenland Ice Sheet (GrIS) margin fluctuations during the Holocene place empirical constraints on the extent of the GrIS that can be used as benchmark data for ice-sheet climate models. Here, we reconstruct the early Holocene ice margin history of the Søndre Isortoq region of western Greenland to evaluate the response of the GrIS to Holocene climate change. The moraines in this region are part of an extensive moraine system known as the Fjord Stade moraines, which have been nearly continuously traced throughout western Greenland. These moraines have been directly dated to 9.2 and 8.2 ka in the Disko Bugt region, suggesting that they represent a readvance or stillstand of the GrIS in response to the 9.3 and 8.2 ka abrupt cooling events, respectively. However, because the Fjord Stade moraines have not been directly and precisely dated elsewhere, it is unclear whether the entire western GrIS margin responded to these events or not. To address this issue, we selected boulders from two sites in the Søndre Isortoq region for cosmogenic 10Be exposure dating. In Nunatarssuaq, we sampled eight erratic boulders perched on bedrock beyond and inside of the Fjord Stade moraines. Samples from Qátqatsiaq include nine Fjord Stade moraine boulders and seven erratic boulders that bracket the moraines. We found that the Fjord Stade moraines in the Søndre Isortoq region were abandoned at ~9 ka and that they may be correlated with the outer Fjord Stade moraines in Disko Bugt. If the western GrIS margin did respond to the 9.3 ka cooling event, the later age of ~9 ka at Søndre Isortoq could suggest that land-terminating sectors of the GrIS are less sensitive to centennial-scale climate change than their marine-terminating counterparts. In addition, exposure ages for moraine boulders and boulders inside the moraines are indistinguishable within dating uncertainties, indicating that once initiated, retreat from the Fjord Stade moraines occurred rapidly.

  16. 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

  17. Late glacial 10Be ages for glacial landforms in the upper region of the Taibai glaciation in the Qinling Mountain range, China

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Liu, Liang; Chen, Yixin; Liu, Beibei; Harbor, Jonathan M.; Cui, Zhijiu; Liu, Rui; Liu, Xiao; Zhao, Xu

    2016-01-01

    Glacial landforms are well preserved on Taibai Mountain (3767 m), the main peak of the Qinling mountain range located south of the Loess Plateau and east of the Qinghai-Tibet Plateau. The timing and extent of Quaternary glaciation in the study area is important for reconstructing Quaternary environmental change however numerical ages for glaciation in this study area have not previously been well resolved. Using terrestrial in situ cosmogenic nuclides we dated four samples collected from two glacially eroded rock steps in the upper part of a valley near the main peak, in an area previously identified as having been occupied by ice during the Taibai glaciation. The 10Be results are all late glacial in age: 18.6 ± 1.1 ka, 16.9 ± 1.0 ka, 16.9 ± 1.1 ka and 15.1 ± 1.0 ka. The spatial pattern of ages in the valley suggests fast retreat, with horizontal and vertical retreat rates estimated to be on the order of 0.4 and 0.09 m a-1, respectively. A simple extrapolation of these retreat rates from the ages at the two sample sites suggests that the glacier retreat began during Last Glacial Maximum and that glaciers disappeared from the main peak by about 15 ka.

  18. 10Be cosmic-ray exposure dating of moraines and rock avalanches in the Upper Romanche valley (French Alps): Evidence of two glacial advances during the Late Glacial/Holocene transition

    NASA Astrophysics Data System (ADS)

    Chenet, Marie; Brunstein, Daniel; Jomelli, Vincent; Roussel, Erwan; Rinterknecht, Vincent; Mokadem, Fatima; Biette, Melody; Robert, Vincent; Léanni, Laëtitia

    2016-09-01

    Cosmic-ray exposure (CRE) dating of moraines allow glacier fluctuations and past climate change reconstructions. In the French Alps, there is a lack of moraine dating for the Late Glacial/Holocene transition period. Here we present a chronology of glacier advances in the Upper Romanche valley (French Alps - Massif des Ecrins) based on 10Be CRE dating. CRE ages of moraines of 13.0 ± 1.1 ka and 12.4 ± 1.5 ka provide evidence for two stages of glacial advance or standstill at the end of the Late Glacial. The CRE dating of a rock avalanche deposit at 12.2 ± 1.5 ka is attributed to post-glacial debuttressing and reveals rapid deglaciation at the end of the Late Glacial. A CRE age of 7.1 ± 0.7 ka of a second mass-wasting, whose triggering factor is unidentified so far, indicates that up to an altitude of 2300 m a.s.l., the valley was ice-free as of ∼7 kyr at the latest. The re-evaluation of 21 moraine 10Be CRE ages from nine glacial valleys across the Alps shows multiple glacial advances occurring at the Late Glacial/Holocene transition. These results lead to a re-evaluation of the importance of cooling events during the Allerød and the Younger Dryas in the Alps.

  19. Cosmic-ray exposure ages of pallasites

    NASA Astrophysics Data System (ADS)

    Herzog, G. F.; Cook, D. L.; Cosarinsky, M.; Huber, L.; Leya, I.; Park, J.

    2015-01-01

    We analyzed cosmogenic nuclides in metal and/or silicate (primarily olivine) separated from the main-group pallasites Admire, Ahumada, Albin, Brahin, Brenham, Esquel, Finmarken, Glorieta Mountain, Huckitta, Imilac, Krasnojarsk, Marjalahti, Molong, Seymchan, South Bend, Springwater, and Thiel Mountains and from Eagle Station. The metal separates contained an olivine fraction which although small, <1 wt% in most cases, nonetheless contributes significantly to the budgets of some nuclides (e.g., up to 35% for 21Ne and 26Al). A correction for olivine is therefore essential and was made using model calculations and/or empirical relations for the production rates of cosmogenic nuclides in iron meteoroids and/or measured elemental concentrations. Cosmic-ray exposure (CRE) ages for the metal phases of the main-group pallasites range from 7 to 180 Ma, but many of the ages cluster around a central peak near 100 Ma. These CRE ages suggest that the parent body of the main-group pallasites underwent a major break-up that produced most of the meteorites analyzed. The CRE age distribution for the pallasites overlaps only a small fraction of the distribution for the IIIAB iron meteorites. Most pallasites and IIIAB irons originated in different collisions, probably on different parent bodies; a few IIIABs and pallasites may have come out of the same collision but a firm conclusion requires further study. CRE ages calculated from noble gas and radionuclide data of the metal fraction are higher on average than the 21Ne exposure ages obtained for the olivine samples. As the metal and olivine fractions were taken in most cases from different specimens, the depth-dependency of the production rate ratio 10Be/21Ne in metal, not accounted for in our calculations, may explain the difference.

  20. The 10Be contents of SNC meteorites

    NASA Technical Reports Server (NTRS)

    Pal, D. K.; Tuniz, C.; Moniot, R. K.; Savin, W.; Vajda, S.; Kruse, T.; Herzog, G. F.

    1986-01-01

    Several authors have explored the possibility that the Shergottites, Nakhlites, and Chassigny (SNC) came from Mars. The spallogenic gas contents of the SNC meteorites have been used to: constrain the sizes of the SNC's during the last few million years; to establish groupings independent of the geochemical ones; and to estimate the likelihood of certain entries in the catalog of all conceivable passages from Mars to Earth. The particular shielding dependence of Be-10 makes the isotope a good probe of the irradiation conditions experienced by the SNC meteorites. The Be-10 contents of nine members of the group were measured using the technique of accelerator mass spectrometry. The Be-10 contents of Nakhla, Governador Valadares, Chassigny, and probably Lafayette, about 20 dpm/kg, exceed the values expected from irradiation of the surface of a large body. The Be-10 data therfore do not support scenario III of Bogard et al., one in which most of the Be-10 in the SNC meteorites would have formed on the Martian surface; they resemble rather the Be-10 contents found in many ordinary chondrites subjected to 4 Pi exposures. The uncertainties of the Be-10 contents lead to appreciable errors in the Be-10 ages, t(1) = -1/lambda ln(1 Be-10/Be-10). Nonetheless, the Be-10 ages are consistent with the Ne-21 ages calculated assuming conventional, small-body production rates and short terrestrial ages for the finds. It is believed that this concordance strengthens the case for at least 3 different irradiation ages for the SNC meteorites. Given the similar half-thicknesses of the Be-10 and Ne-21 production rates, the ratios of the Be-10 and Ne-21 contents do not appear consistent with common ages for any of the groups. In view of the general agreement between the Be-10 and Ne-21 ages it does not seem useful at this time to construct multiple-stage irradiation histories for the SNC meteorites.

  1. Complex exposure histories for meteorites with "short" exposure ages

    NASA Astrophysics Data System (ADS)

    Herzog, G. F.; Vogt, S.; Albrecht, A.; Xue, S.; Fink, D.; Klein, J.; Middleton, R.; Weber, H. W.; Schultz, L.

    1997-05-01

    We report measurements of 26Al and 10Be activities in nine ordinary chondrites and of the light noble gas concentrations and 36Cl and 41Ca activities in subsets of those meteorites. All but Murray have low 21Ne concentrations (<1.0 (10-8 cm3 STP/g), and have previously been used to estimate 21Ne production rates. Ladder Creek, Murchison, Sena, and Timochin have inventories of cosmogenic radionuclides compatible with a single stage of irradiation and give 21Ne production rates consistent with the standard L-chondrite value of ~0.33 ( 10-8 cm3 STP/g-My. In contrast, Cullison, Guenie, Shaw, and Tsarev experienced complex irradiation histories. They and several other meteorites with low nominal exposure ages also have lower 3He/21Ne ratios than expected based on their 22Ne/21Ne ratios. A general association between low 21Ne contents and 3He losses suggests that meteorites with short lifetimes often occupy orbits with small perihelia. Meteorites with low 21Ne contents, one-stage exposure histories, and losses of cosmogenic 3He are rare, however. Possible explanations for the scarcity are 1) statistical; 2) that it is harder for more deeply buried proto-meteoroids to lose gas in a liberating collision; and 3) that it is harder to insert more deeply buried proto-meteoroids directly into orbits with small perihelia.

  2. 10Be dating of Neogene halite

    NASA Astrophysics Data System (ADS)

    Belmaker, Reuven; Lazar, Boaz; Beer, Jürg; Christl, Marcus; Tepelyakov, Natalya; Stein, Mordechai

    2013-12-01

    Direct radioactive dating of ancient halite formations is difficult because this mineral typically lacks conventionally datable material. We describe an attempt to date Neogene halite using the cosmogenic isotope 10Be (T1/2 = 1.39 Ma). We dated marine-derived salt deposits from the Sedom and Amora (The Hebrew forms of Sodom and Gomorrah) Formations, Dead Sea basin, Israel. To verify whether Be is incorporated into marine halite we measured the stable isotope 9Be, 7Be (the short lived “cosmogenic brother” of 10Be having T1/2 = 53.3 d), and 10Be in evaporation pans of sea-salt production plants. The data suggest that seawater beryllium is incorporated into the halite with a halite-brine distribution coefficient, (KD) of about unity. A 10Be/9Be decay curve constructed for Sedom Formation halite yielded an age that lies in the range of ∼2-6 Ma. The 10Be decay curve constructed for Sedom Formation halite yielded an age that lies in the range of 3-5 Ma. This age is consistent with previous estimates of the Sedom Formation age. Furthermore, this age lies in the same range of 10Be in situ ages obtained on the lacustrine Erq El Ahmer Formation located in the northern Jordan Valley. This may imply that during the Mid Pliocene the Sedom Lagoon, the water-body that deposited the Sedom Formation, might have been already disconnected from the open sea.

  3. Cosmic-ray Exposure Ages of Meteorites

    NASA Astrophysics Data System (ADS)

    Herzog, G. F.

    2003-12-01

    The classic idea of a cosmic-ray exposure (CRE) age for a meteorite is based on a simple but useful picture of meteorite evolution, the one-stage irradiation model. The precursor rock starts out on a parent body, buried under a mantle of material many meters thick that screens out cosmic rays. At a time ti, a collision excavates a precursor rock - a "meteoroid." The newly liberated meteoroid, now fully exposed to cosmic rays, orbits the Sun until a time tf, when it strikes the Earth, where the overlying blanket of air (and possibly of water or ice) again shuts out almost all cosmic rays (cf. Masarik and Reedy, 1995). The quantity tf-ti is called the CRE age, t. To obtain the CRE age of a meteorite, we measure the concentrations in it of one or more cosmogenic nuclides (Table 1), which are nuclides that cosmic rays produce by inducing nuclear reactions. Many shorter-lived radionuclides excluded from Table 1 such as 22Na (t1/2=2.6 yr) and 60Co (t1/2=5.27 yr) can also furnish valuable information, but can be measured only in meteorites that fell within the last few half-lives of those nuclides (see, e.g., Leya et al. (2001) and references therein). Table 1. Cosmogenic nuclides used for calculating exposure ages NuclideHalf-lifea (Myr) Radionuclides 14C0.005730 59Ni0.076 41Ca0.1034 81Kr0.229 36Cl0.301 26Al0.717 10Be1.51 53Mn3.74 129I15.7 Stable nuclides 3He 21Ne 38Ar 83Kr 126Xe a http://www2.bnl.gov/ton. CRE ages have implications for several interrelated questions. From how many different parent bodies do meteorites come? How well do meteorites represent the population of the asteroid belt? How many distinct collisions on each parent body have created the known meteorites of each type? How often do asteroids collide? How big and how energetic were the collisions that produced meteoroids? What factors control the CRE age of a meteorite and how do meteoroid orbits evolve through time? We will touch on these questions below as we examine the data.By 1975, the CRE ages of

  4. Airborne particle exposure and extrinsic skin aging.

    PubMed

    Vierkötter, Andrea; Schikowski, Tamara; Ranft, Ulrich; Sugiri, Dorothea; Matsui, Mary; Krämer, Ursula; Krutmann, Jean

    2010-12-01

    For decades, extrinsic skin aging has been known to result from chronic exposure to solar radiation and, more recently, to tobacco smoke. In this study, we have assessed the influence of air pollution on skin aging in 400 Caucasian women aged 70-80 years. Skin aging was clinically assessed by means of SCINEXA (score of intrinsic and extrinsic skin aging), a validated skin aging score. Traffic-related exposure at the place of residence was determined by traffic particle emissions and by estimation of soot in fine dust. Exposure to background particle concentration was determined by measurements of ambient particles at fixed monitoring sites. The impact of air pollution on skin aging was analyzed by linear and logistic regression and adjusted for potential confounding variables. Air pollution exposure was significantly correlated to extrinsic skin aging signs, in particular to pigment spots and less pronounced to wrinkles. An increase in soot (per 0.5 × 10(-5) per m) and particles from traffic (per 475  kg per year and square km) was associated with 20% more pigment spots on forehead and cheeks. Background particle pollution, which was measured in low residential areas of the cities without busy traffic and therefore is not directly attributable to traffic but rather to other sources of particles, was also positively correlated to pigment spots on face. These results indicate that particle pollution might influence skin aging as well.

  5. Exposure ages of carbonaceous chondrites, 1

    NASA Technical Reports Server (NTRS)

    Nishiizumi, K.; Arnold, J. R.; Caffee, M. W.; Finkel, R. C.; Southon, J. R.; Nagai, H.; Honda, M.; Sharma, P.; Imamura, M.; Kobayashi, K.

    1993-01-01

    The recent exposure histories of carbonaceous chondrites have been investigated using cosmogenic radionuclides. Our results may indicate a clustering of exposure ages of C1 and C2 chondrites into two peaks, 0.2 My and 0.6 My, perhaps implying two collisional events of Earth-crossing parent bodies. Among carbonaceous chondrites are some having short exposure ages which Mazor et al. hypothesized cluster into a small number of families. This hypothesis is based on spallogenic Ne-21 exposure ages, which in some instances are difficult to determine owing to the large amounts of trapped noble gases in carbonaceous chondrites. Also, since Ne-21 is stable, it integrates a sample's entire exposure history, so meteorites with complex exposure histories are difficult to understand using exclusively Ne-21. Cosmogenic radionuclides provide an alternative means of determining the recent cosmic ray exposure duration. To test the hypothesis of Mazor et al. we have begun a systematic investigation of exposure histories of Antarctic and non-Antarctic carbonaceous chondrites especially C2s.

  6. 26Al and 10Be Activities of Lodranites and Winona

    NASA Astrophysics Data System (ADS)

    Herzog, G. F.; Xue, S.; Klein, J.; Juenemann, D.; Middleton, R.

    1993-07-01

    Noble gas measurements by [1] indicate that four lodranites LEW 88280, Lodran (a fall), MAC 88177, and Yamato 791491 have the same cosmic ray exposure age of a few million years. The elevated ^22Ne/^21Ne ratios of these lodranites, from 1.22 to 1.28 [1], suggest that shielding was light and production rates appreciably lower than in average chondrites. Cosmic-ray irradiation in space for, say, 4 My would bring ^26Al and ^10Be to within 2% and 16% of their respective saturation values. Thus measurement of ^26Al may provide information about production rates and shielding and ^10Be about exposure age. We separated magnetically metal- and silicate-rich material from the four lodranites mentioned above and from Winona. The ^26Al and/or ^10Be activities (Table 1) were measured by accelerator mass spectrometry [2] with the statistical 1-sigma precision shown; the activities are thought to have an overall accuracy of 6-8%. Although the metal phases were etched with HF, they retained some silicate. To get a quantitative indication of the amounts of silicate present, the Mg concentrations in aliquots of the dissolved metal samples (Table 1) were measured by ICP/MS. The Mg, Al, Ca, Ti, Mn, and Fe contents of the silicate phases were determined by DCP emission spectrometry [3]. The measured activities in silicates from LEW 88280, Lodran, and Y 791491 resemble one another closely: The average ^26Al and ^10Be activities are 50.9 and 16.7 dpm/kg compared to estimated production rates of about 55 and 23 dpm/kg. These results lead to an exposure age of ~3.3 My, but do not indicate substantial lowering of production rates. The ^26Al and ^10Be contents of MAC 88177 are about half the values expected at saturation under normal shielding and are lower than those in the other three lodranites. These results are consistent with the very light shielding inferred from the exceptionally high ^22Ne/^21Ne ratio of 1.28, and perhaps with some lowering due to terrestrial age. Kirsten et al. [4

  7. Detailed chronology of a giant Pleistocene rock-avalanche sequence in the hyperarid southern Peru revealed by jointly applied 10Be and 3He cosmic ray exposure dating : The Study case of the Cerro Caquilluco landslide complex.

    NASA Astrophysics Data System (ADS)

    Swann, Zerathe; Laurence, Audin; Carlos, Benavente; Régis, Braucher; Pierre-Henri, Blard; Didier, Bourlès; Julien, Carcaillet; Fabrizio, Delgado; Pascal, Lacroix; Valderrama Patricio, Murillo; Aster Team

    2015-04-01

    suggesting sequential failures, this object appeared as a good target to bring additional knowledge on the previously exposed issues. Our goal was to use TCN and to sample a maximum of individual lobes to be able to discuss: (i) the time of recurrence of successive extreme events, (ii) the respective roles of past climate variations versus earthquake forcing on the landslide trigger, and (iii) the impact of these mass remobilizations on local erosion rates compared to fluvial erosion rates and tectonic uplift rates (both known in this region). On average, three samples were extracted from individual meter-scale boulders sampled on seven different lobes of debris (~20 samples). Due to the lack of quartz in that volcanic lithology, 10Be was extracted from feldspaths for all samples. Half were additionally processed for 3He measurements on pyroxene, allowing to reduce the uncertainty on the derived exposure ages and to solve the production equation for both time and erosion variables. The obtained ages show a perfect consistency with the pattern of erosion, geomorphic surfaces and relative position of each lobes (i.e. younger from the toe to the top). These results highlight sequential failures staggered at the Pleistocene timescale, with some surprising time of recurrence ranging from 30 to 100 ka that may correspond to the main last climate variations in that region. Crosta, G.B., Hermanns, R.L., Frattini, P., Valbuzzi, E., Valagussa, A., 2014a. Large slope instabilities in Northern Chile: Inventory, Characterisation and Possible Triggers. In: Proceedings of the 3rd world landslide Forum, 2-6 June 2014, Bejing, p 6. DOI: 10.1007/978/-3-319-04996-0_28. Crosta, G.B., Paolo, F., Elena, V., Hermanns, R.L., 2014b. The Cerro Caquilluco-Cerrillos Negros Giant Rock Avalanches (Tacna, Peru). IAEG - Torino 2014, N°159. McPhillips, D., Bierman, P.R., Rood, D.H., 2014. Millennial-scale record of landslides in the Andes consistent with earthquake trigger. Nature Geoscience, DOI: 10

  8. Inner gorges incision history: A proxy for deglaciation? Insights from Cosmic Ray Exposure dating (10Be and 36Cl) of river-polished surfaces (Tinée River, SW Alps, France)

    NASA Astrophysics Data System (ADS)

    Rolland, Y.; Petit, C.; Saillard, M.; Braucher, R.; Bourlès, D.; Darnault, R.; Cassol, D.

    2017-01-01

    10Be and 36Cl Cosmic Ray Exposure (CRE) dating performed on river polished surfaces of river gorges in a mountain-to-sea river system in the French SW Alps highlights transient erosional events involving incision rates >10 mm a-1. These events took place during the last two major deglaciation phases following (1) the Last Glacial Maximum (LGM) at 16-14 ka, (2) the Younger Dryas at 8-11 ka, and during the warm and humid Holocene climatic optimum at 4-5 ka. These periods of high incision rates (3- > 30 mma-1) alternated with periods of low incision rates (<1 mm a-1), which probably correspond to a long-term equilibrium between incision and relative uplift. The Alpine river staircase shape profiles evidence local and transient responses that are ascribed to cumulate disequilibrium after the long-time-spanned glaciations. After each glaciation, rivers rush down to get closer to their equilibrium profile. Incision is amplified both by the sediment discharge due to the erosion of moraines and by landslides triggered by the glacier retreat.

  9. Absolute calibration of 10Be AMS standards

    NASA Astrophysics Data System (ADS)

    Nishiizumi, Kunihiko; Imamura, Mineo; Caffee, Marc W.; Southon, John R.; Finkel, Robert C.; McAninch, Jeffrey

    2007-05-01

    The increased detection sensitivity offered by AMS has dramatically expanded the utility of 10Be. As these applications become more sophisticated attention has focused on the accuracy of the 10Be standards used to calibrate the AMS measurements. In recent years it has become apparent that there is a discrepancy between two of the most widely used 10Be AMS standards, the ICN 10Be standard and the NIST 10Be standard. The ICN (ICN Chemical & Radioisotope Division) 10Be AMS standard was calibrated by radioactive decay counting. Dilutions, ranging from 5 × 10 -13 to 3 × 10 -1110Be/Be, have been prepared and are extensively used in many AMS laboratories. The NIST 10Be standard, prepared at the National Institute of Standards and Technology (NIST), is calibrated by mass spectrometric isotope ratio measurements. To provide an independent calibration of the 10Be standards we implanted a known number of 10Be atoms in both Si detectors and Be foil targets. The 10Be concentrations in these targets were measured by AMS. The results were compared with both the ICN and NIST AMS standards. Our 10Be measurements indicate that the 10Be/ 9Be isotopic ratio of the ICN AMS standard, which is based on a 10Be half-life of 1.5 × 10 6 yr, is 1.106 ± 0.012 times lower than the nominal value. Since the decay rate of the ICN standard is well determined, the decrease in 10Be/ 9Be ratio requires that the 10Be half-life be reduced to (1.36 ± 0.07) × 10 6 yr. The quoted uncertainty includes a ±5% uncertainty in the activity measurement carried out by ICN. In a similar fashion, we determined that the value of the NIST 10Be standard (SRM4325) is (2.79 ± 0.03) × 10 -1110Be/ 9Be, within error of the certified value of (2.68 ± 0.14) × 10 -11. The Lawrence Livermore National Laboratory (LLNL) internal standards were also included in this study. We conclude that the 9Be(n, γ) neutron cross section is 7.8 ± 0.23 mb, without taking into account the uncertainty in the neutron irradiation.

  10. 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

  11. Solar exposure(s) and facial clinical signs of aging in Chinese women: impacts upon age perception.

    PubMed

    Flament, Frederic; Bazin, Roland; Qiu, Huixia; Ye, Chengda; Laquieze, Sabine; Rubert, Virginie; Decroux, Aurelie; Simonpietri, Elisa; Piot, Bertrand

    2015-01-01

    A new reference clinical atlas of facial signs dedicated to photoaging was applied to 301 Chinese women of various ages through standardized photographs. Such approach aimed at better describing the facial changes induced by both real/chronological age and sun exposure and their respective impact on two subcohorts of different behavior with regard to sun exposure. A total of 28 various facial signs were individually graded according to their severity by a panel of experts, and a perceived apparent age of each subject was assessed. Results showed that the severity of major signs significantly increased rather linearly with age, with a higher rate in sun-exposed subjects as compared with subjects who regularly avoid sun exposure. The severity of facial signs, all impacted by sun exposure, better correlated with perceived apparent age than real/chronological age. The protocol used in the present work, similar to that previously applied to two cohorts of French women, assigned a greater impact of sun exposure in the facial aging signs of Asian women - all clinical signs are influenced by extrinsic factors - as compared with Caucasian women of comparable ages, likely related to much more intense ultraviolet (UV) radiation.

  12. Prenatal Marijuana Exposure and Intelligence Test Performance at Age 6

    ERIC Educational Resources Information Center

    Goldschmidt, Lidush; Richardson, Gale A.; Willford, Jennifer; Day, Nancy L.

    2008-01-01

    A study was conducted on lower income population women who were moderate users of marijuana to examine the effects of prenatal marijuana exposure on children's intellectual development at the age of six. Results concluded that the Cognitive deficits noticed at the age of six were specific to verbal and quantitative reasoning and short-term memory.

  13. 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.

  14. Econometric model for age- and population-dependent radiation exposures

    SciTech Connect

    Sandquist, G.M.; Slaughter, D.M. ); Rogers, V.C.

    1991-01-01

    The economic impact associated with ionizing radiation exposures in a given human population depends on numerous factors including the individual's mean economic status as a function age, the age distribution of the population, the future life expectancy at each age, and the latency period for the occurrence of radiation-induced health effects. A simple mathematical model has been developed that provides an analytical methodology for estimating the societal econometrics associated with radiation effects are to be assessed and compared for economic evaluation.

  15. Military blast exposure, ageing and white matter integrity.

    PubMed

    Trotter, Benjamin B; Robinson, Meghan E; Milberg, William P; McGlinchey, Regina E; Salat, David H

    2015-08-01

    Mild traumatic brain injury, or concussion, is associated with a range of neural changes including altered white matter structure. There is emerging evidence that blast exposure-one of the most pervasive causes of casualties in the recent overseas conflicts in Iraq and Afghanistan-is accompanied by a range of neurobiological events that may result in pathological changes to brain structure and function that occur independently of overt concussion symptoms. The potential effects of brain injury due to blast exposure are of great concern as a history of mild traumatic brain injury has been identified as a risk factor for age-associated neurodegenerative disease. The present study used diffusion tensor imaging to investigate whether military-associated blast exposure influences the association between age and white matter tissue structure integrity in a large sample of veterans of the recent conflicts (n = 190 blast-exposed; 59 without exposure) between the ages of 19 and 62 years. Tract-based spatial statistics revealed a significant blast exposure × age interaction on diffusion parameters with blast-exposed individuals exhibiting a more rapid cross-sectional age trajectory towards reduced tissue integrity. Both distinct and overlapping voxel clusters demonstrating the interaction were observed among the examined diffusion contrast measures (e.g. fractional anisotropy and radial diffusivity). The regions showing the effect on fractional anisotropy included voxels both within and beyond the boundaries of the regions exhibiting a significant negative association between fractional anisotropy and age in the entire cohort. The regional effect was sensitive to the degree of blast exposure, suggesting a 'dose-response' relationship between the number of blast exposures and white matter integrity. Additionally, there was an age-independent negative association between fractional anisotropy and years since most severe blast exposure in a subset of the blast-exposed group

  16. Military blast exposure, ageing and white matter integrity

    PubMed Central

    Trotter, Benjamin B.; Robinson, Meghan E.; Milberg, William P.; McGlinchey, Regina E.

    2015-01-01

    Mild traumatic brain injury, or concussion, is associated with a range of neural changes including altered white matter structure. There is emerging evidence that blast exposure—one of the most pervasive causes of casualties in the recent overseas conflicts in Iraq and Afghanistan—is accompanied by a range of neurobiological events that may result in pathological changes to brain structure and function that occur independently of overt concussion symptoms. The potential effects of brain injury due to blast exposure are of great concern as a history of mild traumatic brain injury has been identified as a risk factor for age-associated neurodegenerative disease. The present study used diffusion tensor imaging to investigate whether military-associated blast exposure influences the association between age and white matter tissue structure integrity in a large sample of veterans of the recent conflicts (n = 190 blast-exposed; 59 without exposure) between the ages of 19 and 62 years. Tract-based spatial statistics revealed a significant blast exposure × age interaction on diffusion parameters with blast-exposed individuals exhibiting a more rapid cross-sectional age trajectory towards reduced tissue integrity. Both distinct and overlapping voxel clusters demonstrating the interaction were observed among the examined diffusion contrast measures (e.g. fractional anisotropy and radial diffusivity). The regions showing the effect on fractional anisotropy included voxels both within and beyond the boundaries of the regions exhibiting a significant negative association between fractional anisotropy and age in the entire cohort. The regional effect was sensitive to the degree of blast exposure, suggesting a ‘dose-response’ relationship between the number of blast exposures and white matter integrity. Additionally, there was an age-independent negative association between fractional anisotropy and years since most severe blast exposure in a subset of the blast

  17. Controls on the distribution of cosmogenic 10Be across shore platforms

    NASA Astrophysics Data System (ADS)

    Hurst, Martin D.; Rood, Dylan H.; Ellis, Michael A.

    2017-01-01

    Quantifying rates of erosion on cliffed coasts across a range of timescales is vital for understanding the drivers and processes of coastal change and for assessing risks posed by future cliff retreat. Historical records cover at best the last 150 years; cosmogenic isotopes, such as 10Be could allow us to look further into the past to assess coastal change on millennial timescales. Cosmogenic isotopes accumulate in situ near the Earth surface and have been used extensively to quantify erosion rates, burial dates and surface exposure ages in terrestrial landscapes over the last 3 decades. More recently, applications in rocky coast settings have quantified the timing of mass wasting events, determined long-term averaged rates of cliff retreat and revealed the exposure history of shore platforms. In this contribution, we develop and explore a numerical model for the accumulation of 10Be on eroding shore platforms. In a series of numerical experiments, we investigated the influence of topographic and water shielding, dynamic platform erosion processes, the presence and variation in beach cover, and heterogeneous distribution of erosion on the distribution of 10Be across shore platforms. Results demonstrate that, taking into account relative sea level change and tides, the concentration of 10Be is sensitive to rates of cliff retreat. Factors such as topographic shielding and beach cover act to reduce 10Be concentrations on the platform and may result in overestimation of cliff retreat rates if not accounted for. The shape of the distribution of 10Be across a shore platform can potentially reveal whether cliff retreat rates are declining or accelerating through time. Measurement of 10Be in shore platforms has great potential to allow us to quantify long-term rates of cliff retreat and platform erosion.

  18. Constraints on Exposure Ages of Lunar and Asteroidal Regolith Particles

    NASA Technical Reports Server (NTRS)

    Berger, Eve L.; Keller, Lindsay P

    2014-01-01

    Mineral grains in lunar and asteroidal regolith samples provide a unique record of their interaction with the space environment. Exposure to the solar wind results in implantation effects that are preserved in the rims of grains (typically the outermost 100 nm), while impact processes result in the accumulation of vapor-deposited elements, impact melts and adhering grains on particle surfaces. These processes are collectively referred to as space weathering. A critical element in the study of these processes is to determine the rate at which these effects accumulate in the grains during their space exposure. For small particulate samples, one can use the density of solar flare particle tracks to infer the length of time the particle was at the regolith surface (i.e., its exposure age). We have developed a new technique that enables more accurate determination of solar flare particle track densities in mineral grains <50 micron in size that utilizes focused ion beam (FIB) sample preparation combined with transmission electron microscopy (TEM) imaging. We have applied this technique to lunar soil grains from the Apollo 16 site (soil 64501) and most recently to samples from asteroid 25143 Itokawa returned by the Hayabusa mission. Our preliminary results show that the Hayabusa grains have shorter exposure ages compared to typical lunar soil grains. We will use these techniques to re-examine the track density-exposure age calibration from lunar samples reported by Blanford et al. (1975).

  19. Childhood sensorineural hearing loss: effects of combined exposure with aging or noise exposure later in life.

    PubMed

    Aarhus, Lisa; Tambs, Kristian; Nafstad, Per; Bjørgan, Eskil; Engdahl, Bo

    2016-05-01

    The aim of the study was to examine childhood high-frequency sensorineural hearing loss (HF-SNHL) and the effects of combined exposure with aging or noise exposure on HF hearing thresholds in adulthood. Population-based cohort study of 30,003 adults (mean age 40 years) underwent an audiometry and completed a hearing questionnaire. At age 7-13 years, the same people had participated in a longitudinal school hearing investigation, in which 283 participants were diagnosed with HF-SNHL [PTA 3-8 kHz ≥ 25 dB HL (mean 45 dB HL), worse hearing ear], and 29,720 participants had normal hearing thresholds. The effect of childhood HF-SNHL on adult hearing threshold was significantly moderated by age. Age stratified analyses showed that the difference in HF hearing thresholds between adults with and without childhood HF-SNHL was 33 dB (95 % CI 31-34) in young adults (n = 173, aged 20-39 years) and 37 dB (95 % CI 34-39) in middle-aged adults (n = 110, aged 40-56 years). The combined exposure of childhood HF-SNHL and noise exposure showed a simple additive effect. It appears to be a super-additive effect of childhood-onset HF-SNHL and aging on adult hearing thresholds. An explanation might be that already damaged hair cells are more susceptible to age-related degeneration. To exclude possible birth cohort effects, the finding should be confirmed by a study with several audiometries in adulthood.

  20. Extremely eroded or incredibly young - 10Be depth profile dating of moraines in the Swiss Midlands

    NASA Astrophysics Data System (ADS)

    Wüthrich, Lorenz; Zech, Roland; Haghipour, Negar; Gnägi, Christian; Christl, Markus; Ivy-Ochs, Susan; Veit, Heinz

    2014-05-01

    During the Pleistocene, glaciers advanced repeatedly from the Alps into the Swiss Midlands. The exact extent and timing are still under debate, even for the last glacial advances. Decalcification depths, for example, increase from west to east in the western Swiss Midlands and have been interpreted to indicate that the Valais (Rhone) glacier may have been less extensive during the global Last Glacial Maximum (LGM) at 20 ka than assumed so far [1]. In an attempt to provide more quantitative age control, we applied 10Be depth profile dating [2] on moraines at two locations. Steinhof has previously been dated to the global LGM based on exposure ages from four boulders [3], and Niederbuchsiten presumably lies outside the last glacial ice extent [1]. The 10Be concentrations at both sites decrease consistently with depth, but are very similar. Assuming only a few decimeters of erosion since moraine deposition, we obtain apparent exposure ages of ~20 ka. Niederbuchsiten would thus be unexpectedly young, implying a much more extensive extent of the LGM glacier than assumed so far. Alternatively, if the till at Niederbuchsiten was deposited during or before the penultimate glaciation (>130 ka), the surprisingly low 10Be concentrations indicate several meters of erosion during the last glacial cycle and/or the Holocene, which seems to be at odds with the deep and intensive soil formation. References: [1] Bitterli et al. (2011) Geologischer Atlas der Schweiz, Blatt 1108. [2] Hidy et al. (2010) Geochem. Geophys. Geosyst. 11, doi:10.1029/2010GC003084. [3] Ivy- Ochs et al. (2004) Ecl. Geol. Helv. 97, 47-55.

  1. Low 10Be concentrations in geomorphic studies: Problems, strategies, and examples

    NASA Astrophysics Data System (ADS)

    Savi, Sara; Tofelde, Stefanie; Wittmann, Hella; Binnie, Steven; Heinze, Stefan; Schildgen, Taylor

    2016-04-01

    In the last two decades, the use of in situ cosmogenic nuclides for the quantification of exogenic processes and the determination of exposure ages of landforms has seen a fast and broad expansion. Among the group of terrestrial cosmogenic nuclides that can be used to study geomorphic processes (e.g. 10Be, 26Al, 36Cl, 3He, 21Ne and 22Ne), in situ-produced 10Be is the most widely used, especially for the quantification of denudation rates. However, there are a number of problematic issues related to the use of cosmogenic nuclide techniques in rapidly evolving landscapes because of the typically low 10Be abundancies. The difficulties encountered in these settings are mainly related to (1) the mass of clean quartz that can be obtained and thus the total amount of 10Be available, and (2) the backgrounds of the sample preparation and measurement processes. In order to improve measurements in these circumstances, a series of steps can be taken into consideration during field work and sample preparation to help improve the final results. We discuss the quality of the blanks, blank corrections, and the limits of detection of the technique in the specific case of low concentration samples. Based on a number of different synthetic scenarios, we demonstrate the importance of blank corrections and utility of determination limits, and we highlight how these parameters may affect the reliability and meaningfulness of the results. This information in turn helps to illustrate how low-concentration data should be interpreted and reported.

  2. 36Cl-36Ar Exposure Ages of Chondritic Metals

    NASA Astrophysics Data System (ADS)

    Graf, Th.; Caffee, M. W.; Finkel, R. C.; Marti, K.; Nishiizumi, K.; Ponganis, K. V.

    1995-09-01

    Metal separates were prepared to determine ^36Cl-^36Ar exposure ages for six H4 p.m. falls (with reported bulk exposure ages of 4 to 10Ma), for ten H5 a.m. falls (T(sub)e = 4-10 Ma) and for the Acapulco meteorite (T(^36Cl-^36Ar)= 5.7 Ma). This dating method uses production rate ratios P(^36Cl)/P(^36Ar) and is independent of the shielding-sensitive absolute production rates. It is also known that for protons the production rate ratio is rather insensitive to changes in the energy spectrum; the dependence of this ratio for secondary neutrons is at present less understood. First results were already reported [1]. The cosmic-ray-produced ^3He/^38Ar ratios show a bimodal distribution with two clusters at about 15 and about 9 (Fig. 1). About half of the ^3He is produced via ^3H which is known to diffuse in metal at relatively low temperatures. Therefore, Fig. 1 provides evidence for a quasi-continuous loss of ^3H from such metals. If this loss mechanism is due to solar heating, perihelia <1 AU are indicated for these meteorites. Losses are prominent for H5 a.m. falls, but not for H4 p.m. falls. The orbital implications are consistent with those already known from the time-of-fall parameter (p.m. falls / total falls) which was used in the selection of the H4,H5 sample sets [2]. The exposure age histograms of both H groups show the well known clusters at about 7 Ma. The width of the exposure age peaks differ, however, and the collisional break-up event can be further constrained. Except for Nassirah, all members of the H4 p.m. group fall into the range 7.0 +/- 0.3 Ma. Bulk rock ages (8.2-9.3 Ma) [3] as well as the ^36Cl-^36Ar age (8.3 Ma) of Nassirah are higher and may indicate that this meteorite does not belong to the collisional event. We observe a small but systematic difference in calculated exposure ages by the ^36Cl-^36Ar method, when compared with ages obtained by conventional noble gas production rates. This shift (about 10%) does not appear to be dependent on

  3. Telomere dynamics may link stress exposure and ageing across generations.

    PubMed

    Haussmann, Mark F; Heidinger, Britt J

    2015-11-01

    Although exposure to stressors is known to increase disease susceptibility and accelerate ageing, evidence is accumulating that these effects can span more than one generation. Stressors experienced by parents have been reported to negatively influence the longevity of their offspring and even grand offspring. The mechanisms underlying these long-term, cross-generational effects are still poorly understood, but we argue here that telomere dynamics are likely to play an important role. In this review, we begin by surveying the current connections between stress and telomere dynamics. We then lay out the evidence that exposure to stressors in the parental generation influences telomere dynamics in offspring and potentially subsequent generations. We focus on evidence in mammalian and avian studies and highlight several promising areas where our understanding is incomplete and future investigations are critically needed. Understanding the mechanisms that link stress exposure across generations requires interdisciplinary studies and is essential to both the biomedical community seeking to understand how early adversity impacts health span and evolutionary ecologists interested in how changing environmental conditions are likely to influence age-structured population dynamics.

  4. Telomere dynamics may link stress exposure and ageing across generations

    PubMed Central

    Haussmann, Mark F.; Heidinger, Britt J.

    2015-01-01

    Although exposure to stressors is known to increase disease susceptibility and accelerate ageing, evidence is accumulating that these effects can span more than one generation. Stressors experienced by parents have been reported to negatively influence the longevity of their offspring and even grand offspring. The mechanisms underlying these long-term, cross-generational effects are still poorly understood, but we argue here that telomere dynamics are likely to play an important role. In this review, we begin by surveying the current connections between stress and telomere dynamics. We then lay out the evidence that exposure to stressors in the parental generation influences telomere dynamics in offspring and potentially subsequent generations. We focus on evidence in mammalian and avian studies and highlight several promising areas where our understanding is incomplete and future investigations are critically needed. Understanding the mechanisms that link stress exposure across generations requires interdisciplinary studies and is essential to both the biomedical community seeking to understand how early adversity impacts health span and evolutionary ecologists interested in how changing environmental conditions are likely to influence age-structured population dynamics. PMID:26538535

  5. UV aging and outdoor exposure correlation for EVA PV encapsulants

    NASA Astrophysics Data System (ADS)

    Reid, Charles G.; Bokria, Jayesh G.; Woods, Joseph T.

    2013-09-01

    A widely cited approximation in the solar industry is that "one week of xenon arc weather-o-meter exposure is equivalent to one year of field exposure." This statement is a generalization of test data generated in the mid-1990s as part of the NREL managed PVMaT-3 project. This approximation was based entirely upon yellowing of first generation EVA-based encapsulants in two different accelerated test conditions, xenon arc and mirror accelerated outdoor aging. First generation EVA encapsulants were developed by STR under the JPL solar project (1975-1986) and exhibit yellowing (or browning) with exposure to UV and heat. This yellowing mechanism was understood and resolved with newer generation EVA encapsulation products introduced in late 1990s. Modules were manufactured at the end of the PVMaT-3 project that included both older and newer generation encapsulants. Those modules were on a two-axis tracker in Arizona from 1996 to 2012 and are now undergoing diagnostic tests. Older generation standard-cure encapsulant used in these modules exhibited severe browning over cells and the modules exhibit approximate power loss of about two percent per year. This same standard cure encapsulant material has been tested with updated xenon arc exposure methods and optical transmission tests to estimate the loss in power due only to browning and reduction in light transmission.

  6. Dynamics of erosion in a compressional mountain range revealed by 10Be paleoerosion rates

    NASA Astrophysics Data System (ADS)

    Val, P.; Hoke, G. D.; Fosdick, J. C.; Wittmann, H.

    2015-12-01

    The temporal evolution of erosion over million-year timescales is key to understanding the evolution of mountain ranges and adjacent fold-and-thrust belts. While models of orogenic wedge evolution predict an instantaneous response of erosion to pulses of rock uplift, stream-power based landscape evolution models predict catchment-wide erosion maxima that lag behind a rock uplift pulse. Here, we explore the relationships between rock uplift, erosion, and sediment deposition in the Argentine Precordillera fold-and-thrust belt at 30°S where extensive previous work documents deformation, climate and sediment accumulation histories. Sandstone samples spanning 8.8 to 1.8 Ma were collected from the previously dated wedge-top (Iglesia) and foredeep basins (Bermejo) for quartz purification and 10Be extraction. 10Be concentrations due to burial and exhumation were estimated and subtracted from the measured concentrations and yielded the inherited 10Be concentrations, which were then corrected for sample magnetostratigraphic age. The inherited concentrations were then used to calculate paleoerosion rates. We modeled various pre-burial and post-burial exposure scenarios in order to assess potential sources of uncertainty in the recovered paleoerosion rates. The modeling results reveal that pre-burial and post-burial exposure periods only marginally affect our results. By combining the 10Be-derived paleoerosion rates and geomorphic observations with detrital zircon provenance, we document the isolation of the wedge-top basin, which was later reconnected by an upstream migrating pulse of erosion in a process that was directly controlled by thrust activity and base level. The data further indicate that the attainment of maximum upland erosion rates lags maximum rates of deformation and subsidence over million-year timescales. The magnitudes and causes of the erosional delays shed new light on the catchment erosional response to tectonic deformation and rock uplift in orogenic

  7. Exposure and terrestrial ages of four Allan Hills Antarctic meteorites

    NASA Technical Reports Server (NTRS)

    Kirsten, T.; Ries, D.; Fireman, E. L.

    1978-01-01

    Terrestrial ages of meteorites are based on the amount of cosmic-ray-produced radioactivity in the sample and the number of observed falls that have similar cosmic-ray exposure histories. The cosmic-ray exposures are obtained from the stable noble gas isotopes. Noble gas isotopes are measured by high-sensitivity mass spectrometry. In the present study, the noble gas contents were measured in four Allan Hill meteorites (No. 5, No. 6, No. 7, and No. 8), whose C-14, Al-26, and Mn-53 radioactivities are known. These meteorites are of particular interest because they belong to a large assemblage of distinct meteorites that lie exposed on a small (110 sq km) area of ice near the Allan Hills.

  8. Cumulative Lead Exposure and Age-related Hearing Loss: The VA Normative Aging Study

    PubMed Central

    Park, Sung Kyun; Elmarsafawy, Sahar; Mukherjee, Bhramar; Spiro, Avron; Vokonas, Pantel S.; Nie, Huiling; Weisskopf, Marc G.; Schwartz, Joel; Hu, Howard

    2010-01-01

    Although lead has been associated with hearing loss in occupational settings and in children, little epidemiologic research has been conducted on the impact of cumulative lead exposure on age-related hearing loss in the general population. We determined whether bone lead levels, a marker of cumulative lead exposure, are associated with decreased hearing ability in 448 men from the Normative Aging Study, seen between 1962 and 1996 (2,264 total observations). Air conduction hearing thresholds were measured at 0.25 to 8 kHz and pure tone averages (PTA) (mean of 0.5, 1, 2 and 4 kHz) were computed. Tibia and patella lead levels were measured using K x-ray fluorescence between 1991 and 1996. In cross-sectional analyses, after adjusting for potential confounders including occupational noise, patella lead levels were significantly associated with poorer hearing thresholds at 2, 3, 4, 6 and 8 kHz and PTA. The odds of hearing loss significantly increased with patella lead levels. We also found significant positive associations between tibia lead and the rate change in hearing thresholds at 1, 2, and 8 kHz and PTA in longitudinal analyses. Our results suggest that chronic low-level lead exposure may be an important risk factor for age-related hearing loss and reduction of lead exposure could help prevent or delay development of age-related hearing loss. PMID:20638461

  9. Dating chert using in-situ produced 10Be: Possible complications revealed on landslide scarps through a comparison with 36Cl applied to coexisting limestone.

    NASA Astrophysics Data System (ADS)

    Zerathe, Swann; Braucher, Régis; Lebourg, Thomas; Leani, Leatitia; Manetti, Michel; Bourles, Didier

    2013-04-01

    This abstract and presentation highlights potential complications that may arise while using in situ produced 10Be to date diagenetic silica (chert)exposure or burial event. The initiation and evolution of large gravitational collapses in sedimentary rocks were constrained using cosmic ray exposure dating. Because these collapses occurred in a stratigraphic level composed of chert (diagenetic silica) concretions interbedded in limestone layers, their development was studied by performing in situ-produced 36Cl and 10Be concentration measurements in both the limestone and coexisting diagenetic silica (chert), respectively. Following the routinely used decontamination and preparation protocols for 10Be produced in diagenetic silica, large discrepancies were observed with exposure ages determined by 36Cl within carbonate for samples originating from the same scarp. While 36Cl exposure ages were clustered as expected for a unique single gravitational event, 10Be exposure ages were scattered along the same studied scarps. To determine the origin of such a bias, petrological investigations were carried out for chert (diagenetic silica). Thin sections highlighted a complex mineralogical texture characterized by remnant silicified ooids showing calcitic cores, calcite inclusions and a dominant amorphous hydrated silica (grain > 20 μm). To decipher and characterize the potential origins of the excess measured 10Be within diagenetic silica, all samples were first reprocessed following the routine decontamination protocol (HCL-H2SiF6 leachings and three partial HF dissolutions) but starting from three different grain size fractions (GS1: 1000-500, GS2: 500-250 and GS3: 250-50 μm). The resulting concentrations clearly showed a decreasing 10Be content as a function of the grain size, but still yielded 10Be exposure ages significantly higher than 36Cl counterparts. Because potential adsorption of 10Be at the surface of amorphous silica grains was suspected, partial dissolution

  10. Acceleration of cardiovascular-biological age by amphetamine exposure is a power function of chronological age

    PubMed Central

    Norman, Amanda; Hulse, Gary Kenneth

    2017-01-01

    Background Amphetamine abuse is becoming more widespread internationally. The possibility that its many cardiovascular complications are associated with a prematurely aged cardiovascular system, and indeed biological organism systemically, has not been addressed. Methods Radial arterial pulse tonometry was performed using the SphygmoCor system (Sydney). 55 amphetamine exposed patients were compared with 107 tobacco smokers, 483 non-smokers and 68 methadone patients (total=713 patients) from 2006 to 2011. A cardiovascular-biological age (VA) was determined. Results The age of the patient groups was 30.03±0.51–40.45±1.15 years. This was controlled for with linear regression. The sex ratio was the same in all groups. 94% of amphetamine exposed patients had used amphetamine in the previous week. When the (log) VA was regressed against the chronological age (CA) and a substance-type group in both cross-sectional and longitudinal models, models quadratic in CA were superior to linear models (both p<0.02). When log VA/CA was regressed in a mixed effects model against time, body mass index, CA and drug type, the cubic model was superior to the linear model (p=0.001). Interactions between CA, (CA)2 and (CA)3 on the one hand and exposure type were significant from p=0.0120. The effects of amphetamine exposure persisted after adjustment for all known cardiovascular risk factors (p<0.0001). Conclusions These results show that subacute exposure to amphetamines is associated with an advancement of cardiovascular-organismal age both over age and over time, and is robust to adjustment. That this is associated with power functions of age implies a feed-forward positively reinforcing exacerbation of the underlying ageing process. PMID:28243315

  11. Space erosion and cosmic ray exposure ages of stony meteorites

    NASA Astrophysics Data System (ADS)

    Rubincam, David Parry

    2015-01-01

    Space erosion from dust impacts may set upper limits on the cosmic ray exposure (CRE) ages of stony meteorites. A meteoroid orbiting within the asteroid belt is bombarded by both cosmic rays and interplanetary dust particles. Galactic cosmic rays penetrate only the first few meters of the meteoroid; deeper regions are shielded. The dust particle impacts create tiny craters on the meteoroid's surface, eroding it away by abrasion at a particular rate. Hence a particular point inside a meteoroid accumulates cosmic ray products only until that point wears away, limiting CRE ages. The results would apply to other regolith-free surfaces in the Solar System as well, so that abrasion may set upper CRE age limits which depend on the dusty environment. Calculations based on N. Divine's dust populations and on micrometeoroid cratering indicate that large stony meteoroids in circular ecliptic orbits at 2 AU will record 21Ne CRE ages of ∼176 × 106 y if dust masses are in the range 10-21-10-3 kg. This is in broad agreement with the maximum observed CRE ages of ∼100 × 106 y for stones. High erosion rates in the inner Solar System may limit the CRE ages of Near-Earth Asteroids (NEAs) to ∼120 × 106 y. A characteristic of erosion is that the neon concentrations tend to rise as the surface of the meteorite is approached, rather than drop off as for meteorites with fixed radii. Pristine samples recovered from space may show the rise. If the abrasion rate for stones were a factor of ∼6 larger than found here, then the ages would drop into the 30 × 106 y range, so that abrasion alone might be able to explain many CRE ages. However, there is no strong evidence for higher abrasion rates, and in any case would probably not be fast enough to explain the youngest ages of 0.1-1 × 106 y. Further, space erosion is much too slow to explain the ∼600 × 106 y ages of iron meteorites.

  12. CM Carbonaceous Chondrite Lithologies and Their Space Exposure Ages

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael; Gregory, Timothy; Takenouchi, Atsushi; Nishiizumi, Kunihiko; Trieman, Alan; Berger, Eve; Le, Loan; Fagan, Amy; Velbel, Michael; Imae, Naoya; Yamaguchi, Akira

    2015-01-01

    The CMs are the most commonly falling C chondrites, and therefore may be a major component of C-class asteroids, the targets of several current and future space missions. Previous work [1] has concluded that CM chondrites fall into at least four distinct cosmic ray space exposure (CRE) age groups (0.1 million years, 0.2 million years, 0.6 million years and greater than 2.0 million years), an unusually large number, but the meaning of these groupings is unclear. It is possible that these meteorites came from different parent bodies which broke up at different times, or instead came from the same parent body which underwent multiple break-up events, or a combination of these scenarios, or something else entirely. The objective of this study is to investigate the diversity of lithologies which make up CM chondrites, in order to determine whether the different exposure ages correspond to specific, different CM lithologies, which permit us to constrain the history of the CM parent body(ies). We have already reported significant petrographic differences among CM chondrites [2-4]. We report here our new results.

  13. Conditional and indirect effects of age of first exposure on PTSD symptoms.

    PubMed

    Miller-Graff, Laura E; Scrafford, Kathryn; Rice, Catherine

    2016-01-01

    Childhood violence exposure (CVE) in formative developmental years may have potent effects on severity and complexity of post-traumatic stress symptoms (PTSS) in adulthood, yet little research has examined the role of age of first exposure in the context of polyvictimization or gone beyond an examination of direct effects. The current study examines the specific associations between age of first exposure, total CVE, and posttraumatic stress symptoms in adulthood. Further, the conditional and indirect effects of age of first exposure on posttraumatic stress symptoms were examined. We hypothesized that age of first exposure to violence would be associated with higher total violence exposure across childhood, thereby predicting current posttraumatic stress symptom severity (i.e., indirect effect). We also postulated that age of first exposure would affect the relationship between total violence exposure and posttraumatic stress symptoms such that earlier exposure would exacerbate the effects of violence exposure (i.e., conditional effect). Participants included 269 violence-exposed adults recruited through MTurk; the mean age of first CVE was 6 years (SD=3.29). Conditional process models indicated that age of first exposure was significantly associated with higher total childhood violence exposure, which in turn, was significantly associated with current posttraumatic stress symptoms in all domains. Further, a conditional effect of age of first exposure was present such that the relationship between total exposure to violence and symptoms of hyperarousal was stronger for those first exposed at earlier ages. Findings provide support suggesting the particular potency of early trauma on regulatory response systems.

  14. 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

  15. Cosmic Ray Exposure Ages, Ar-Ar Ages, and the Origin and History of Eucrites

    NASA Technical Reports Server (NTRS)

    Wakefield, Kelli; Bogard, Donald; Garrison, Daniel

    2004-01-01

    HED meteorites likely formed at different depths on the large asteroid 4-Vesta, but passed through Vesta-derived, km-sized intermediary bodies (Vestoids), before arriving at Earth. Most eucrites and diogenites (and all howardites) are brecciated, and impact heating disturbed or reset the K-Ar ages (and some Rb-Sr ages) of most eucrites in the time period of approx. 3.4 - 4.1 Gyr ago. Some basaltic eucrites and most cumulate eucrites, however, are not brecciated. We recently showed that the Ar-39 - Ar-40 ages for several of these eucrites tightly cluster about a value of 4.48 +/- 0.02 Gyr, and we argue that this time likely represents a single large impact event on Vesta, which ejected these objects from depth and quenched their temperatures. A different parent body has been suggested for cumulate eucrites, although the Ar-Ar ages argue for a common parent. Similarities in the cosmic-ray (space) exposure ages for basaltic eucrites and diogenites also have been used to infer a common parent body for some HEDs. Here we present CRE ages of several cumulate and unbrecciated basaltic (UB) eucrites and compare these with CRE ages of other HEDs. This comparison also has some interesting implications for the relative locations of various HED types on Vesta and/or the Vestoids.

  16. 10Be chronometry of bedrock-to-soil conversion rates

    NASA Astrophysics Data System (ADS)

    Monaghan, Marc C.; McKean, James; Dietrich, William; Klein, Jeffrey

    1992-07-01

    We report concentrations of cosmogenic 10Be ( t1/2 = 1.5 × 10 6 yrs) in soil excavated from a soil-mantled hillslope in Black Diamond Mines Regional Park, Contra Costa County, California. The most striking features of the data are: (1) the similarity in the downward decreasing trends of 10Be concentrations in two soil profiles collected 75 m apart, (2) the coincidence in each soil profile of the soil/bedrock interface (as defined by visual inspection of soil pits) and the level at which 10Be concentrations attain very low values ( ˜4 × 10 6 atoms/g), and (3) the extremely low 10Be concentrations in the underlying regolith (0.5 × 10 6 atoms/gram). The inventory of 10Be in these soils is low, equivalent to about 6000 yrs of 10Be accumulation in a soil initially containing no 10Be. On the basis of these measurements, and with the aid of simple models of soil ( 10Be) motions on the hillslope, we conclude that 10Be loss from the surface is dominated by its removal in soil by creep. We calculate local rates of bedrock-to-soil conversion of between 0.15 and 0.27 km/10 6 yrs. Comparing these with uplift rates determined for coastal regions of California indicates that soil creep alone is capable of removing soil from the local geomorphic system at a rate equivalent to the rate of uplift of much of the coast.

  17. 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

  18. Cosmogenic exposure-age chronologies of Pinedale and Bull Lake glaciations in greater Yellowstone and the Teton Range, USA

    USGS Publications Warehouse

    Licciardi, J.M.; Pierce, K.L.

    2008-01-01

    We have obtained 69 new cosmogenic 10Be surface exposure ages from boulders on moraines deposited by glaciers of the greater Yellowstone glacial system and Teton Range during the middle and late Pleistocene. These new data, combined with 43 previously obtained 3He and 10Be ages from deposits of the northern Yellowstone outlet glacier, establish a high-resolution chronology for the Yellowstone-Teton mountain glacier complexes. Boulders deposited at the southern limit of the penultimate ice advance of the Yellowstone glacial system yield a mean age of 136??13 10Be ka and oldest ages of ???151-157 10Be ka. These ages support a correlation with the Bull Lake of West Yellowstone, with the type Bull Lake of the Wind River Range, and with Marine Isotope Stage (MIS) 6. End moraines marking the maximum Pinedale positions of outlet glaciers around the periphery of the Yellowstone glacial system range in age from 18.8??0.9 to 16.5??1.4 10Be ka, and possibly as young as 14.6??0.7 10Be ka, suggesting differences in response times of the various ice-cap source regions. Moreover, all dated Pinedale terminal moraines in the greater Yellowstone glacial system post-date the Pinedale maximum in the Wind River Range by ???4-6 kyr, indicating a significant phase relationship between glacial maxima in these adjacent ranges. Boulders on the outermost set and an inner set of Pinedale end moraines enclosing Jenny Lake on the eastern Teton front yield mean ages of 14.6??0.7 and 13.5??1.1 10Be ka, respectively. The outer Jenny Lake moraines are partially buried by outwash from ice on the Yellowstone Plateau, hence their age indicates a major standstill of an expanded valley glacier in the Teton Range prior to the Younger Dryas, followed closely by deglaciation of the Yellowstone Plateau. These new glacial chronologies are indicative of spatially variable regional climate forcing and temporally complex patterns of glacier responses in this region of the Rocky Mountains during the Pleistocene

  19. 10Be concentrations of Red soils in Southwest Japan and its possibility of dating

    NASA Astrophysics Data System (ADS)

    Maejima, Y.; Matsuzaki, H.; Nakano, C.

    2004-08-01

    10Be concentrations of six Red soils distributed in Southwest Japan ranged from 0.8 × 108 to 2.7 × 109 atoms g-1, and minimum absolute ages were estimated by inventory of meteoric 10Be. The results are follows: Red soils on Toyota derived from granite (⩽25 ka), Kashii derived from Tertiary shale (⩽24 ka), Akiyoshidai derived from limestone (⩽110 ka), Okinawa Island derived from Kunigami gravel bed (⩽9 ka) and Ogasawara Island derived from agglomerate and Boninite (⩽22 and ⩽7 ka) were obtained, respectively. Soil age except with Akiyoshidai indicated younger age. It suggested that the loss of 10Be from the soil was caused by leaching of 10Be or by soil erosion, and 10Be is susceptible to leaching out from these Red soils under the humid climate condition such as Southwest Japan.

  20. Do Fungi Transport 10Be During Wood Degradation?

    NASA Astrophysics Data System (ADS)

    Conyers, G.; Granger, D. E.

    2010-12-01

    Meteoric cosmogenic 10Be is increasingly used to determine erosion and soil transport rates. To calculate these rates, it is assumed that 10Be is a conservative passive tracer of soil particles. However, there is experimental evidence that beryllium is mobilized in natural soils complexed with organic acids. For example, up to 50% of beryllium can be mobilized by humic acids in soils at pH 7 (Takahashi et al., 1999). Beryllium is also known to be taken up in plants such as tobacco and vegetables (World Health Organization, 1990) at ppm levels, primarily as organic acid chelates. It is not known to what extent biological beryllium transport in the environment affects the cosmogenic 10Be budget, or how it influences beryllium mobility. In this study, we address a problem recognized early in the development of meteoric 10Be methods. It has been observed that decayed organic matter in soils and sediments contains very high concentrations of 10Be of up to 109-1010 atoms/g (Lundberg, et al., 1983). On the other hand, living trees contain much lower concentrations of 106 atoms/g (Klein et al., 1982). The driving question for this study is how 10Be becomes bound to decayed organic matter. Direct fallout seems unlikely as the residence time of organic matter in soil is too short. One possibility is that 10Be is transported by fungi. Wood-degrading fungi are known to transport and bioaccumulate metals from large areas, facilitated by acids such as oxalic acid in the fungal hyphae. To test the hypothesis that fungi transport 10Be, we analyzed both intact and fungally degraded wood of oak, hickory, and hemlock. From these data, we reached two conclusions (observations?): 1) Oak has a 10Be concentration of about 2x106 at/g, similar to that observed by Klein et al. (1982). Hickory has a significantly higher concentration of about 3x107 atoms/g, confirming observations that hickory bioaccumulates beryllium. Using these data, the inventory of 10Be in a temperate forest is expected

  1. An inter-comparison of 10Be and 26Al AMS reference standards and the 10Be half-life

    NASA Astrophysics Data System (ADS)

    Fink, David; Smith, Andrew

    2007-06-01

    We have completed a survey and inter-comparison of several 10Be and 26Al standard reference materials (SRMs) that are in routine use at various AMS laboratories to assess their relative values and the accuracy of their quoted nominal ratios. The accelerator measurement cycle, analysis procedure and setup used at the ANTARES AMS facility for this survey are described. We focused on a new set of 10Be and 26Al serial dilutions of standard reference materials (SRMs) prepared by Kuni Nishiizumii at the University of California, Berkeley, and found excellent systematic reproducibility and internal consistency. For other standard materials, minor deviations are evident even when the results have been recalibrated to a common half-life. In particular, we confirm that the NIST 10Be SRM-4325 has a 14% greater 10Be/Be ratio than that certified by NIST when it is calibrated against other SRMs whose ratios have been normalized to a common 1.5 Ma 10Be half-life. In order to investigate this apparent discrepancy, we report on the results of an absolute, normalization independent, measure of the NIST-4325 10Be/Be ratio. Within the constraints of this type of measurement and its systematic errors, we determine an absolute value for the 10Be/Be SRM-4325 ratio in the range 26,050 to 24,800 × 10-15 in support of the certified value of 26,800 × 10-15 given by NIST. We hesitate to directly infer as a consequence that the 10Be half-life is 1.34 Ma because such an inference is contingent on a direct and accurate specific activity in the parent solution, which at present is not available.

  2. /sup 10/Be profiles in lunar surface rock 68815

    SciTech Connect

    Nishiizumi, K.; Imamura, M.; Kohl, C.P.; Nagai, H.; Kobayashi, K.; Yoshida, K.; Yamashita, H.; Reedy, R.C.; Honda, M.; Arnold, J.R.

    1987-01-01

    Cosmic ray produced /sup 10/Be (t/sub 1/2/ = 1.6 x 10/sup 6/ years) activities have been measured in fourteen carefully ground samples of lunar surface rock 68815. The /sup 10/Be profiles from 0 to 4 mm are nearly flat for all three surface angles measured and show a very slight increase with depth from the surface to a depth of 1.5 cm. These depth profiles are in contrast to the SCR (solar cosmic ray) produced /sup 26/Al and /sup 53/Mn profiles measured from these same samples. There is no sign of SCR produced /sup 10/Be in this rock. The discrepancy between the data and the Reedy-Arnold theoretical calculation (about 2 dpm /sup 10/Be/kg at the surface) can be explained in two ways: (1) the low energy proton induced cross sections for /sup 10/Be production from oxygen are really lower than those used in the calculations or, (2) compared to the reported fits for /sup 26/Al and /sup 53/Mn, the solar proton spectral shape is actually softer (exponential rigidity parameter Ro less than 100 MV), the omnidirectional flux above 10 MeV is higher (more than 70 protons/cm/sup 2/ s), and the erosion rate is higher (greater than 1.3 mm/My). /sup 10/Be, as a high energy product, is a very useful nuclide for helping to obtain the SCR spectral shape in the past. 23 refs., 3 figs., 1 tab.

  3. Microscopic three-cluster model of 10Be

    NASA Astrophysics Data System (ADS)

    Lashko, Yu. A.; Filippov, G. F.; Vasilevsky, V. S.

    2017-02-01

    We investigate spectrum of bound and resonance states in 10Be, and scattering of alpha-particles on 6He. For this aim we make use of a three-cluster microscopic model. This model incorporates Gaussian and oscillator basis functions and reduces three-cluster Schrödinger equation to a two-body like many-channel problem with the two-cluster subsystem being in a bound or a pseudo-bound state. Much attention is given to the effects of cluster polarization on spectrum of bound and resonance states in 10Be, and on elastic and inelastic 6He + α scattering.

  4. Cosmogenic 26Al/10Be surface production ratio in Greenland

    NASA Astrophysics Data System (ADS)

    Corbett, Lee B.; Bierman, Paul R.; Rood, Dylan H.; Caffee, Marc W.; Lifton, Nathaniel A.; Woodruff, Thomas E.

    2017-02-01

    The assumed value for the cosmogenic 26Al/10Be surface production rate ratio in quartz is an important parameter for studies investigating the burial or subaerial erosion of long-lived surfaces and sediments. Recent models and data suggest that the production ratio is spatially variable and may be greater than originally thought. Here we present measured 26Al/10Be ratios for 24 continuously exposed bedrock and boulder surfaces spanning 61-77°N in Greenland. Empirical measurements, such as ours, include nuclides produced predominately by neutron-induced spallation with percent-level contributions by muon interactions. The slope of a York regression line fit to our data is 7.3 ± 0.3 (1σ), suggesting that the 26Al/10Be surface production ratio exceeds the commonly used value of 6.75, at least in the Arctic. A higher 26Al/10Be production ratio has implications for multinuclide cosmogenic isotope studies because it results in greater modeled burial durations and erosion rates.

  5. Dating offset fans along the Mojave section of the San Andreas fault using cosmogenic 26Al and 10Be

    USGS Publications Warehouse

    Matmon, A.; Schwartz, D.P.; Finkel, R.; Clemmens, S.; Hanks, T.

    2005-01-01

    Analysis of cosmogenic 10Be and 26Al in samples collected from exposed boulders (n = 20) and from buried sediment (n = 3) from offset fans along the San Andreas fault near Little Rock, California, yielded ages, ranging from 16 to 413 ka, which increase with distance from their source at the mouth of Little Rock Creek. In order to determine the age of the relatively younger fans, the erosion rate of the boulders and the cosmogenic nuclide inheritance from exposure prior to deposition in the fan were established. Cosmogenic nuclide inheritance values that range between 8.5 ?? 103 and 196 ?? 103 atoms 10Be g-1 quartz were determined by measuring the concentrations and ratios of 10Be and 26Al in boulders (n = 10) and fine sediment (n = 7) at the outlet of the present active stream. Boulder erosion rate, ranging between 17 and 160 mm k.y.-1, was estimated by measuring 10Be and 26Al concentrations in nearby bedrock outcrops (n = 8). Since the boulders on the fans represent the most resistant rocks in this environment, we used the lowest rate for the age calculations. Monte Carlo simulations were used to determine ages of 16 ?? 5 and 29 ?? 7 ka for the two younger fan surfaces. Older fans (older than 100 ka) were dated by analyzing 10Be and 26Al concentrations in buried sand samples. The ages of the three oldest fans range between 227 ?? 242 and 413 ?? 185 ka. Although fan age determinations are accompanied by large uncertainties, the results of this study show a clear trend of increasing fan ages with increasing distance from the source near Little Rock Creek and provide a long-term slip rate along this section of the San Andreas fault. Slip rate along the Mojave section of the San Andreas fault for the past 413 k.y. can be determined in several ways. The average slip rate calculated from the individual fan ages is 4.2 ?? 0.9 cm yr-1. A linear regression through the data points implies a slip rate of 3.7 ?? 1.0 cm yr-1. A most probable slip rate of 3.0 ?? 1.0 cm yr-1 is

  6. Aluminum 26, {sup 10}Be, and {sup 36}Cl depth profiles in the Canyon Diablo iron meteorite

    SciTech Connect

    Michlovich, E.S.; Elmore, D.; Vogt, S.; Lipschutz, M.E.; Masarik, J.; Reedy, R.C.

    1994-11-25

    The authors have measured activities of the long-lived cosmogenic radionuclides {sup 26}Al, {sup 10}Be, and {sup 36}Cl in 12 fragments of the iron meteorite Canyon Diablo and have constructed production rate-versus-depth profiles of those radionuclides. Profiles determined using differential particle fluxes calculated with the LAHET code system are in good agreement with {sup 26}Al, {sup 10}Be, and {sup 36}Cl experimental data, but the agreement for {sup 36}Cl was obtained only after neutron-induced cross sections were modified. Profiles calculated with lunar particle fluxes are much lower than experimental Canyon Diablo profiles. The cosmic ray exposure ages of most samples are near 540 m.y. 34 refs., 4 figs., 2 tabs.

  7. Exposure to an enriched environment up to middle age allows preservation of spatial memory capabilities in old age.

    PubMed

    Fuchs, Fanny; Cosquer, Brigitte; Penazzi, Lorène; Mathis, Chantal; Kelche, Christian; Majchrzak, Monique; Barbelivien, Alexandra

    2016-02-15

    In rats, some cognitive capabilities, like spatial learning and memory, are preserved from age-related decline by whole adult life enriched environment (EE) exposure. However, to which extent late EE contributes to such maintenance remains to be investigated. Here we assessed the impact of late housing condition (e.g., from the age of 18 months) on spatial learning and memory of aged rats (24 months) previously exposed or unexposed to EE from young adulthood. The results showed that late EE was not required for spatial memory maintenance in aged rats previously housed in EE. In contrast, late EE mitigates spatial memory deficit in aged rats previously unexposed to EE. These outcomes suggest that EE exposure up to middle age provides a "reserve"-like advantage which supports an enduring preservation of spatial capabilities in old age.

  8. 10Be analysis of a Quaternary weathering profile in the Virginia Piedmont.

    USGS Publications Warehouse

    Pavich, M.J.; Brown, Louis; Valette-Silver, J. Nathalie; Klein, Jeffrey; Middleton, Roy

    1985-01-01

    Samples from a residual weathering profile in the Virginia Piedmont have been analyzed for cosmogenic 10Be. Concentrations are highest in clay-rich soil and decrease exponentially to a depth of about 15 m. Despite uncertainties about the processes by which 10Be may be intercepted before entering the solum and eroded after incorporation, a minimum age may be calculated for the regolith. This calculation is based on the delivery rate of 10Be and its decay rate and suggests that this residual profile developed during a period no shorter than 8 × 105 yr. The calculated minimum age may be within a factor of 2 of maximum-age estimates based on surface lowering by erosion and on the rate of rock weathering to saprolite. The vertical distribution of 10Be in the profile could result from a steady-state balance of deposition, weathering, radioactive decay, and erosion.

  9. Age at exposure and attained age variations of cancer risk in the Japanese A-bomb and radiotherapy cohorts

    SciTech Connect

    Schneider, Uwe; Walsh, Linda

    2015-08-15

    Purpose: Phenomenological risk models for radiation-induced cancer are frequently applied to estimate the risk of radiation-induced cancers at radiotherapy doses. Such models often include the effect modification, of the main risk to radiation dose response, by age at exposure and attained age. The aim of this paper is to compare the patterns in risk effect modification by age, between models obtained from the Japanese atomic-bomb (A-bomb) survivor data and models for cancer risks previously reported for radiotherapy patients. Patterns in risk effect modification by age from the epidemiological studies of radiotherapy patients were also used to refine and extend the risk effect modification by age obtained from the A-bomb survivor data, so that more universal models can be presented here. Methods: Simple log-linear and power functions of age for the risk effect modification applied in models of the A-bomb survivor data are compared to risks from epidemiological studies of second cancers after radiotherapy. These functions of age were also refined and fitted to radiotherapy risks. The resulting age models provide a refined and extended functional dependence of risk with age at exposure and attained age especially beyond 40 and 65 yr, respectively, and provide a better representation than the currently available simple age functions. Results: It was found that the A-bomb models predict risk similarly to the outcomes of testicular cancer survivors. The survivors of Hodgkin’s disease show steeper variations of risk with both age at exposure and attained age. The extended models predict solid cancer risk increase as a function of age at exposure beyond 40 yr and the risk decrease as a function of attained age beyond 65 yr better than the simple models. Conclusions: The standard functions for risk effect modification by age, based on the A-bomb survivor data, predict second cancer risk in radiotherapy patients for ages at exposure prior to 40 yr and attained ages

  10. Constraints on the last deglaciation of the Ross Sea Sector of the West Antarctic Ice Sheet (WAIS) from 10Be dating

    NASA Astrophysics Data System (ADS)

    Bill, N. S.; Clark, P. U.; Kurz, M. D.; Marcott, S. A.; Caffee, M. W.

    2014-12-01

    We present new 10Be surface exposure ages from glacial erratic boulders from several locations in McMurdo Sound in order to constrain the deglacial history of the West Antarctic Ice Sheet. Previous model and field data indicate that the present day Ross Ice Shelf was a grounded ice sheet, with the grounding line extending to near the continental shelf edge during the Last Glacial Maximum (LGM). However, the timing and rate of the last deglaciation of the Ross Sea Sector of the West Antarctic Ice Sheet remain uncertain. We sampled granitic and basaltic erratic boulders for dating with the cosmogenic nuclides 10Be and 3He; in situ 14C dating will be used to assess complex burial histories. The 10Be ages on erratics near or at the upper limit of Ross Sea Drift that do not appear to have inheritance range from 17 to 26 ka. 10Be ages from erratics below the limit of the (LGM) Ross Sea Drift suggest final deglaciation by ~11 ka. New 10Be ages from more highly weathered glacial deposits above the Ross Sea drift near Blue Glacier suggest an age range of 141 to 171 ka.

  11. Arsenite exposure accelerates aging process regulated by the transcription factor DAF-16/FOXO in Caenorhabditis elegans.

    PubMed

    Yu, Chan-Wei; How, Chun Ming; Liao, Vivian Hsiu-Chuan

    2016-05-01

    Arsenic is a known human carcinogen and high levels of arsenic contamination in food, soils, water, and air are of toxicology concerns. Nowadays, arsenic is still a contaminant of emerging interest, yet the effects of arsenic on aging process have received little attention. In this study, we investigated the effects and the underlying mechanisms of chronic arsenite exposure on the aging process in Caenorhabditis elegans. The results showed that prolonged arsenite exposure caused significantly decreased lifespan compared to non-exposed ones. In addition, arsenite exposure (100 μM) caused significant changes of age-dependent biomarkers, including a decrease of defecation frequency, accumulations of intestinal lipofuscin and lipid peroxidation in an age-dependent manner in C. elegans. Further evidence revealed that intracellular reactive oxygen species (ROS) level was significantly increased in an age-dependent manner upon 100 μM arsenite exposure. Moreover, the mRNA levels of transcriptional makers of aging (hsp-16.1, hsp-16.49, and hsp-70) were increased in aged worms under arsenite exposure (100 μM). Finally, we showed that daf-16 mutant worms were more sensitive to arsenite exposure (100 μM) on lifespan and failed to induce the expression of its target gene sod-3 in aged daf-16 mutant under arsenite exposure (100 μM). Our study demonstrated that chronic arsenite exposure resulted in accelerated aging process in C. elegans. The overproduction of intracellular ROS and the transcription factor DAF-16/FOXO play roles in mediating the accelerated aging process by arsenite exposure in C. elegans. This study implicates a potential ecotoxicological and health risk of arsenic in the environment.

  12. Atmospheric deposition of sup 7 Be and sup 10 Be

    SciTech Connect

    Brown, L. ); Stensland, G.J. ); Klein, J.; Middleton, R. )

    1989-01-01

    Measurements of {sup 10}Be in precipitation taken in Hawaii, Illinois and New Jersey over a period of five years are reported. The problem of contamination by the isotope being resuspended on wind blown soil that is also collected is addressed. Rain collected at Mauna Loa, Hawaii has such low values of dust contamination that it has been taken as clean, and the data from Illinois and New Jersey are evaluated on that assumption. The conclusion is that the deposition in a given amount of rain for the non-resuspended component is the same for all three stations, and the authors propose that the annual rate for mid-latitude locations have moderate rainfall is proportional to the local rainfall. {sup 7}Be, which is probably negligibly contributed to the measurements by soil contamination was measured for individual rains in Illinois and found to have a deposition of 1.4 {times} 10{sup 4} atom/cm{sup 3}. The authors have found that concentration variations between precipitation events greater than a factor of 20 exist for both isotopes and that relatively rare, high concentration events dominate deposition, thereby requiring long periods of observation to avoid significant error. Based on their own and other data they conclude that the best value for {sup 10}Be deposition is 1.5 {times} 10{sup 4} atom/cm{sup 3}, uncertain by 20%, and for {sup 7}Be is 1.2 {times} 10{sup 4} atom/cm{sup 3}, uncertain by 25%. A global average deposition rate cannot be inferred directly for either isotope from these kinds of data; however, the theoretical global deposition rate for {sup 10}Be is shown to be consistent with the deposition reported here, if the concentration in equatorial rain is about 3300 atom/g.

  13. Helium breakup states in 10Be and 12Be

    NASA Astrophysics Data System (ADS)

    Freer, M.; Angélique, J. C.; Axelsson, L.; Benoit, B.; Bergmann, U.; Catford, W. N.; Chappell, S. P.; Clarke, N. M.; Curtis, N.; D'arrigo, A.; de Góes Brennard, E.; Dorvaux, O.; Fulton, B. R.; Giardina, G.; Gregori, C.; Grévy, S.; Hanappe, F.; Kelly, G.; Labiche, M.; Le Brun, C.; Leenhardt, S.; Lewitowicz, M.; Markenroth, K.; Marqués, F. M.; Murgatroyd, J. T.; Nilsson, T.; Ninane, A.; Orr, N. A.; Piqueras, I.; Saint Laurent, M. G.; Singer, S. M.; Sorlin, O.; Stuttgé, L.; Watson, D. L.

    2001-03-01

    The breakup of 10,12Be into He clusters has been studied using the p,12C(12Be,6He,6He) and 12C(12Be,4He,6He) inelastic scattering and two neutron transfer reactions with a 378 MeV 12Be beam incident on 12C and (CH2)n targets. Evidence has been found for three new states in 10Be at excitation energies of 13.2, 14.8, and 16.1 MeV, which may be associated with a 4He+6He cluster structure. The evidence for He cluster states in 12Be in the excitation energy range 12 to 25 MeV is also discussed.

  14. Maternal Age at Holocaust Exposure and Maternal PTSD Independently Influence Urinary Cortisol Levels in Adult Offspring

    PubMed Central

    Bader, Heather N.; Bierer, Linda M.; Lehrner, Amy; Makotkine, Iouri; Daskalakis, Nikolaos P.; Yehuda, Rachel

    2014-01-01

    Background: Parental traumatization has been associated with increased risk for the expression of psychopathology in offspring, and maternal posttraumatic stress disorder (PTSD) appears to increase the risk for the development of offspring PTSD. In this study, Holocaust-related maternal age of exposure and PTSD were evaluated for their association with offspring ambient cortisol and PTSD-associated symptom expression. Method: Ninety-five Holocaust offspring and Jewish comparison subjects received diagnostic and psychological evaluations, and 24 h urinary cortisol was assayed by RIA. Offspring completed the parental PTSD questionnaire to assess maternal PTSD status. Maternal Holocaust exposure was identified as having occurred in childhood, adolescence, or adulthood and examined in relation to offspring psychobiology. Results: Urinary cortisol levels did not differ for Holocaust offspring and comparison subjects but differed significantly in offspring based on maternal age of exposure and maternal PTSD status. Increased maternal age of exposure and maternal PTSD were each associated with lower urinary cortisol in offspring, but did not exhibit a significant interaction. In addition, offspring PTSD-associated symptom severity increased with maternal age at exposure and PTSD diagnosis. A regression analysis of correlates of offspring cortisol indicated that both maternal age of exposure and maternal PTSD were significant predictors of lower offspring urinary cortisol, whereas childhood adversity and offspring PTSD symptoms were not. Conclusion: Offspring low cortisol and PTSD-associated symptom expression are related to maternal age of exposure, with the greatest effects associated with increased age at exposure. These effects are relatively independent of the negative consequences of being raised by a trauma survivor. These observations highlight the importance of maternal age of exposure in determining a psychobiology in offspring that is consistent with increased

  15. A first 10Be cosmogenic glacial chronology from the High Atlas, Morocco, during the last glacial cycle.

    NASA Astrophysics Data System (ADS)

    Fink, David; Hughes, Philip; Fenton, Cassie

    2014-05-01

    Glacial geomorphological mapping, 10Be cosmogenic exposure ages of 21 erratics from cirque-valley systems and paleo-glacier climate modelling in the High Atlas Mountains, Morocco (31.1° N, 7.9° W), provides new and novel insights as to the history and evolution of the largest desert region on Earth. The Atlas Mountains display evidence of extensive and multiple Late Pleistocene glaciations whose extent is significantly larger than that recognised by previous workers. The largest glaciers formed in the Toubkal massif where we find 3 distinct phases of glacial advances within the last glacial cycle. The oldest moraines occurring at the lowest elevations have yielded eight 10Be ages ranging from 30 to 88 ka. Six of eight samples from moraines at intermediate elevations gave ages of 19 to 25 ka (2 outliers) which correlates well with the global Last Glacial Maximum (ca. 26-21 ka) and the last termination during marine isotope stage 2. Five erratics from the youngest and most elevated moraines yielded a suite of normally distributed exposure ages from 11 to 13 ka which supports a correlation with the northern hemisphere Younger Dryas (12.9-11.7 ka). The glacial record of the High Atlas effectively reflects moisture supply to the north-western Sahara Desert and can provide an indication of shifts between arid and pluvial conditions. The plaeo equilibrium line altitudes (ELA) of these three glacier phases was more than 1000 m lower than the predicted ELA based on today's temperatures. Glacier-climate modelling indicates that for each of these glacier phases climate was not only significantly cooler than today, but also much wetter. The new evidence on the extent, timing and palaeoclimatic significance of glaciations in this region has major implications for understanding moisture transfer between the North Atlantic Ocean and the Sahara Desert during Pleistocene cold stages.

  16. Probabilistic assessment of exposure to cosmetic products by French children aged 0-3 years.

    PubMed

    Ficheux, A S; Dornic, N; Bernard, A; Chevillotte, G; Roudot, A C

    2016-08-01

    Very few exposure data are available for children in Europe and worldwide. The aim of this study was to assess the exposure to cosmetic products used on children aged 0-3 years using recent consumption data generated for the French population. Exposure was assessed using a probabilistic method for 24 products including cleanser, skin care, fragrance, solar and bottom products. The exposure data obtained in this study for children aged 0-3 years were higher than the values fixed by the SCCS for all common products: liquid shampoo, face moisturizer cream, toothpaste, shower gel and body moisturizer cream. Exposure was assessed for the first time for many products such as sunscreens, Eau de toilette and massage products. These new French exposure values will be useful for safety assessors and for safety agencies.

  17. AGE-RELATED TOXICITY PATHWAY ANALYSIS IN BROWN NORWAY RAT BRAIN FOLLOWING ACUTE TOLUENE EXPOSURE

    EPA Science Inventory

    The influence of aging on susceptibility to environmental exposures is poorly understood. To investigate-the contribution of different life stages on response to toxicants, we examined the effects of an acute exposure to the volatile organic compound, toluene (0.0 or 1.0 g/kg), i...

  18. 28 CFR 79.14 - Proof of initial exposure prior to age 21.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 28 Judicial Administration 2 2011-07-01 2011-07-01 false Proof of initial exposure prior to age 21. 79.14 Section 79.14 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) CLAIMS UNDER THE RADIATION EXPOSURE COMPENSATION ACT Eligibility Criteria for Claims Relating to Leukemia § 79.14 Proof...

  19. 28 CFR 79.14 - Proof of initial exposure prior to age 21.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 28 Judicial Administration 2 2013-07-01 2013-07-01 false Proof of initial exposure prior to age 21. 79.14 Section 79.14 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) CLAIMS UNDER THE RADIATION EXPOSURE COMPENSATION ACT Eligibility Criteria for Claims Relating to Leukemia § 79.14 Proof...

  20. 28 CFR 79.14 - Proof of initial exposure prior to age 21.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 28 Judicial Administration 2 2014-07-01 2014-07-01 false Proof of initial exposure prior to age 21. 79.14 Section 79.14 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) CLAIMS UNDER THE RADIATION EXPOSURE COMPENSATION ACT Eligibility Criteria for Claims Relating to Leukemia § 79.14 Proof...

  1. 28 CFR 79.14 - Proof of initial exposure prior to age 21.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 28 Judicial Administration 2 2012-07-01 2012-07-01 false Proof of initial exposure prior to age 21. 79.14 Section 79.14 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) CLAIMS UNDER THE RADIATION EXPOSURE COMPENSATION ACT Eligibility Criteria for Claims Relating to Leukemia § 79.14 Proof...

  2. 28 CFR 79.14 - Proof of initial exposure prior to age 21.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Proof of initial exposure prior to age 21. 79.14 Section 79.14 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) CLAIMS UNDER THE RADIATION EXPOSURE COMPENSATION ACT Eligibility Criteria for Claims Relating to Leukemia § 79.14 Proof...

  3. Some correlation of rock exposure ages and regolith dynamics. [in lunar samples

    NASA Technical Reports Server (NTRS)

    Horz, F.; Gibbons, R. V.; Gault, D. E.; Hartung, J. B.; Brownlee, D. E.

    1975-01-01

    Exposure age information on lunar rocks and regolith turnover rates are correlated. If plotted in a cumulative fashion, the distribution of spallogenic noble-gas exposure ages is remarkably parallel to the rate at which various fractions of the regolith surface are cratered and/or excavated. It appears that the rate at which lunar rocks are excavated from within the regolith is strongly controlled by the impact environment. Some suggestions for future refinement of regolith dynamics are presented.

  4. Age of first bilingual language exposure as a new window into bilingual reading development*

    PubMed Central

    Kovelman, Ioulia; Baker, Stephanie A.; Petitto, Laura-Ann

    2009-01-01

    How does age of first bilingual language exposure affect reading development in children learning to read in both of their languages? Is there a reading advantage for monolingual English children who are educated in bilingual schools? We studied children (grades 2–3, ages 7–9) in bilingual Spanish–English schools who were either from Spanish-speaking homes (new to English) or English-speaking homes (new to Spanish), as compared with English-speaking children in monolingual English schools. An early age of first bilingual language exposure had a positive effect on reading, phonological awareness, and language competence in both languages: early bilinguals (age of first exposure 0–3 years) outperformed other bilingual groups (age of first exposure 3–6 years). Remarkably, schooling in two languages afforded children from monolingual English homes an advantage in phoneme awareness skills. Early bilingual exposure is best for dual language reading development, and it may afford such a powerful positive impact on reading and language development that it may possibly ameliorate the negative effect of low SES on literacy. Further, age of first bilingual exposure provides a new tool for evaluating whether a young bilingual has a reading problem versus whether he or she is a typically-developing dual-language learner. PMID:19823598

  5. Age of first bilingual language exposure as a new window into bilingual reading development.

    PubMed

    Kovelman, Ioulia; Baker, Stephanie A; Petitto, Laura-Ann

    2008-07-01

    How does age of first bilingual language exposure affect reading development in children learning to read in both of their languages? Is there a reading advantage for monolingual English children who are educated in bilingual schools? We studied children (grades 2-3, ages 7-9) in bilingual Spanish-English schools who were either from Spanish-speaking homes (new to English) or English-speaking homes (new to Spanish), as compared with English-speaking children in monolingual English schools. An early age of first bilingual language exposure had a positive effect on reading, phonological awareness, and language competence in both languages: early bilinguals (age of first exposure 0-3 years) outperformed other bilingual groups (age of first exposure 3-6 years). Remarkably, schooling in two languages afforded children from monolingual English homes an advantage in phoneme awareness skills. Early bilingual exposure is best for dual language reading development, and it may afford such a powerful positive impact on reading and language development that it may possibly ameliorate the negative effect of low SES on literacy. Further, age of first bilingual exposure provides a new tool for evaluating whether a young bilingual has a reading problem versus whether he or she is a typically-developing dual-language learner.

  6. Heterogeneity of variation of relative risk by age at exposure in the Japanese atomic bomb survivors.

    PubMed

    Little, Mark P

    2009-08-01

    General reductions in cancer relative risk with increasing age at exposure are observed in the Japanese atomic bomb survivors and in other groups. However, there has been little evidence of heterogeneity in such trends by cancer type within the Japanese cohort, nor for cancer-type variations in other factors (sex, attained age) that modify relative risk. A recent report on the Japanese atomic bomb survivors published by Preston et al. in 2007 suggests that solid cancer relative risk exhibits a U-shaped relationship with age at exposure, and is initially decreasing and then increasing at older exposure ages. In this report, we reanalyse the latest Japanese atomic bomb survivor solid cancer mortality and incidence data analysed by Preston and co-workers, stratifying by cancer subtype where possible, the stratification being both in relation to the baseline and the radiation-associated excess. We find highly statistically significant (P < 0.001) variations of relative risk by cancer type, and statistically significant variations by cancer type in the adjustments for sex (P = 0.010) and age at exposure (P = 0.013) to the relative risk. There is no statistically significant (P > 0.2) variation by cancer type in the adjustment of relative risk for attained age. Although, for all incident solid cancers, there is marginally statistically significant (P = 0.033) variation of relative risk with a quadratic log-linear function of age at exposure, there is much weaker variation in the relative risk of solid cancer mortality (P > 0.1). However, the manner in which relative risk varies with age at exposure is qualitatively similar for incidence and mortality, so one should not make too much of these differences between the two datasets. Stratification by solid cancer type slightly weakens the evidence for quadratic variation in relative risk by age at exposure (P = 0.060).

  7. New exposure ages for the Last Glacial Cycle in the Sanabria Lake region (northwestern Spain)

    NASA Astrophysics Data System (ADS)

    Rodríguez-Rodríguez, Laura; Jiménez-Sánchez, Montserrat; Domínguez-Cuesta, María Jose; Rinterknecht, Vincent; Pallàs, Raimon; Braucher, Régis; Bourlès, Didier; Valero-Garcés, Blas

    2013-04-01

    The Sanabria Lake region is located in the Trevinca Massif, a mid-latitude mountain area up to 2128 m asl in the northwest corner of the Iberian Peninsula (42oN 6oW). An ice cap glaciation took place during the Last Glacial Cycle in this massif, with an equilibrium line altitude of 1687 m for the Tera glacial outlet at its local maximum (Cowton et al., 2009). A well preserved glacial sequence occurs on an area of 45 km2 around the present Sanabria Lake (1000 m asl) and is composed by lateral and end moraines in close relationship with glaciolacustrine deposits. This sequence shows the ice snout oscillations of the former Tera glacier during the Last Glacial Cycle and offers a good opportunity to compare radiocarbon and OSL- based chronological models with new cosmogenic isotope dates. The new dataset of 10Be exposure ages presented here for the Sanabria Lake moraines is based on measurements conducted on 23 boulders and is compared with previous radiocarbon and OSL data conducted on ice related deposits (Pérez-Alberti et al., 2011; Rodríguez-Rodríguez et al., 2011). Our results are coherent with the available deglaciation radiocarbon chronology, and support a last deglaciation origin for the whole set of end moraines that are downstream the Sanabria Lake (19.2 - 15.7 10Be ka). Discrepancies between results of the different dating methods concern the timing of the local glacial maximum, with the cosmogenic exposure method always yielding the youngest minimum ages. As proposed to explain similar observations made elsewhere (Palacios et al., 2012), reconciling the ages from different dating methods would imply the occurrence of two glacial advances close enough in extent to generate an overlapping polygenic moraine. Cowton, T., Hughes, P.D., Gibbard, P.L., 2009. Palaeoglaciation of Parque Natural Lago de Sanabria, northwest Spain. Geomorphology 108, 282-291. Rodríguez-Rodríguez, L., Jiménez-Sánchez, M., Domínguez-Cuesta, M.J., Rico, M.T., Valero-Garcés, B

  8. Bisphenol A exposure accelerated the aging process in the nematode Caenorhabditis elegans.

    PubMed

    Tan, Ling; Wang, Shunchang; Wang, Yun; He, Mei; Liu, Dahai

    2015-06-01

    Bisphenol A (BPA) is a well-known environmental estrogenic disruptor that causes adverse effects. Recent studies have found that chronic exposure to BPA is associated with a high incidence of several age-related diseases. Aging is characterized by progressive function decline, which affects quality of life. However, the effects of BPA on the aging process are largely unknown. In the present study, by using the nematode Caenorhabditis elegans as a model, we investigated the influence of BPA exposure on the aging process. The decrease in body length, fecundity, and population size and the increased egg laying defection suggested that BPA exposure resulted in fitness loss and reproduction aging in this animal. Lifetime exposure of worms to BPA shortened the lifespan in a dose-dependant manner. Moreover, prolonged BPA exposure resulted in age-related behavior degeneration and the accumulation of lipofuscin and lipid peroxide products. The expression of mitochondria-specific HSP-6 and endoplasmic reticulum (ER)-related HSP-70 exhibited hormetic decrease. The expression of ER-related HSP-4 decreased significantly while HSP-16.2 showed a dose-dependent increase. The decreased expression of GCS-1 and GST-4 implicated the reduced antioxidant ability under BPA exposure, and the increase in SOD-3 expression might be caused by elevated levels of reactive oxygen species (ROS) production. Finally, BPA exposure increased the generation of hydrogen peroxide-related ROS and superoxide anions. Our results suggest that BPA exposure resulted in an accelerated aging process in C. elegans mediated by the induction of oxidative stress.

  9. In situ Be-10-Al-26 exposure ages at Meteor Crater, Arizona

    NASA Technical Reports Server (NTRS)

    Nishiizumi, K.; Kohl, C. P.; Arnold, J. R.; Shoemaker, E. M.; Klein, J.; Fink, D.; Middleton, R.

    1991-01-01

    A new method of dating the surface exposure of rocks from in situ production of Be-10 and Al-26 has been applied to determine the age of Meteor Crater, Arizona. A lower bound on the crater age of 49,200 + or - 1,700 years has been obtained by this method.

  10. Age of First Bilingual Language Exposure as a New Window into Bilingual Reading Development

    ERIC Educational Resources Information Center

    Kovelman, Ioulia; Baker, Stephanie A.; Petitto, Laura-Ann

    2008-01-01

    How does age of first bilingual language exposure affect reading development in children learning to read in both of their languages? Is there a reading advantage for monolingual English children who are educated in bilingual schools? We studied children (grades 2-3, ages 7-9) in "bilingual" Spanish-English schools who were either from…

  11. Long-term exposure to air pollution is associated with biological aging

    PubMed Central

    Ward-Caviness, Cavin K.; Nwanaji-Enwerem, Jamaji C.; Wolf, Kathrin; Wahl, Simone; Colicino, Elena; Trevisi, Letizia; Kloog, Itai; Just, Allan C.; Vokonas, Pantel; Cyrys, Josef; Gieger, Christian; Schwartz, Joel; Baccarelli, Andrea A.; Schneider, Alexandra; Peters, Annette

    2016-01-01

    Long-term exposure to air pollution is associated with age-related diseases. We explored the association between accelerated biological aging and air pollution, a potential mechanism linking air pollution and health. We estimated long-term exposure to PM10, PM2.5, PM2.5 absorbance/black carbon (BC), and NOx via land-use regression models in individuals from the KORA F4 cohort. Accelerated biological aging was assessed using telomere length (TeloAA) and three epigenetic measures: DNA methylation age acceleration (DNAmAA), extrinsic epigenetic age acceleration (correlated with immune cell counts, EEAA), and intrinsic epigenetic age acceleration (independent of immune cell counts, IEAA). We also investigated sex-specific associations between air pollution and biological aging, given the published association between sex and aging measures. In KORA an interquartile range (0.97 μg/m3) increase in PM2.5 was associated with a 0.33 y increase in EEAA (CI = 0.01, 0.64; P = 0.04). BC and NOx (indicators or traffic exposure) were associated with DNAmAA and IEAA in women, while TeloAA was inversely associated with BC in men. We replicated this inverse BC-TeloAA association in the Normative Aging Study, a male cohort based in the USA. A multiple phenotype analysis in KORA F4 combining all aging measures showed that BC and PM10 were broadly associated with biological aging in men. Thus, we conclude that long-term exposure to air pollution is associated with biological aging measures, potentially in a sex-specific manner. However, many of the associations were relatively weak and further replication of overall and sex-specific associations is warranted. PMID:27793020

  12. Effects of Age on Temperature Responses During Exposure to Hypergravity

    NASA Technical Reports Server (NTRS)

    Fung, C.K.; Baer, L. A.; Moran, M. M.; Wang, T. J.; Yuan, F.; Daunton, N. G.; Corcoran, M. L.; Wade, C. E.; Dalfan, Bonnie P. (Technical Monitor)

    2001-01-01

    Rats subjected to centrifugation show a marked decrease in body temperature relating to gravity level. Several studies have indicated, that an initial response to centrifugation is followed by acclimation. To test for differences between young (Y; 2 months) and mature (M; 8 months) rats in their response in temperature, both groups were exposed to hypergravity induced by centrifugation. Thirty-six male rats were divided into four groups according to age and G-load (control (1.0G-Y and 1.0G-M), 2.0G-Y or 2.0G-M) and were housed in pairs in standard vivarium cages. During the 7-day period of centrifugation, temperature was measured every five minutes by surgically implanted telemeters. Body mass was measured daily. We found that initial body temperature in 2.0G-M was less than that of 2.0G-Y. Both hypergravity groups (2.0G-Y and 2.0G-M) showed a decrease in temperature at the onset of centrifugation, and the change in temperature (Delta = 0.5 C) remained the same between the groups. Significant differences persisted with 2.0G-Y recovering to control values in four days and 2.0G-M recovering in five days. These results indicate that the mature animals have a similar response as the younger animals, but take longer to acclimate.

  13. The Relationship of Korean Students' Age and Years of English-as-a-Foreign-Language Exposure with English-Reading Ability: A Cross-Age Study

    ERIC Educational Resources Information Center

    Fitzgerald, Jill; Stenner, A. Jackson; Sanford-Moore, Eleanor E.; Koons, Heather; Bowen, Kimberly; Kim, Kee Hyung

    2015-01-01

    The purpose of the present cross-age study with South Korean students was to investigate the relationship of age and years of English-as-a-foreign-language (EFL) exposure with English-reading ability. The main research question was, "Do individuals' age and number of years of English exposure interact in relation to English-reading…

  14. 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.

  15. Paleodischarge of the Mojave River, southwestern U.S.A, investigated with single-pebble measurements of 10Be

    USGS Publications Warehouse

    Cyr, Andrew J.; Miller, David; Mahan, Shannon

    2015-01-01

    The paleohydrology of ephemeral stream systems is an important constraint on paleoclimatic conditions in arid environments, but remains difficult to constrain quantitatively. For example, sedimentary records of the size and extent of pluvial lakes in the Mojave Desert have been used as a proxy for Quaternary climate variability. Although the delivery mechanisms of this additional water are still being debated, it is generally agreed that the discharge of the Mojave River, which supplied water for several Pleistocene pluvial lakes along its course, must have been significantly greater during lake high stands. We used the 10Be concentrations of 10 individual quartzite pebbles sourced from the San Bernardino Mountains and collected from a ~25 ka strath terrace of the Mojave River near Barstow, Calif., to test whether pebble ages record the timing of large paleodischarge of the Mojave River. Our exposure ages indicate that periods of discharge large enough to transport pebble-sized sediment occurred at least four times over the past ~240 ky; individual pebble ages cluster into four groups with exposure ages of 24.82 ± 2.52 ka (n=3), 55.79 ± 2.59 ka (n=2), 99.14 ± 6.04 ka (n=4) and 239.9 ± 52.16 ka (n=1). These inferred large discharge events occurred during both glacial and interglacial conditions. We demonstrate that bedload materials provide information about the frequency and duration of transport events in river systems. This approach could be further improved with the addition of additional measurements of one or more cosmogenic nuclides coupled with models of river discharge and pebble transport.

  16. Resistance of calves to Cryptosporidium parvum: effects of age and previous exposure.

    PubMed Central

    Harp, J A; Woodmansee, D B; Moon, H W

    1990-01-01

    Cryptosporidium parvum is a coccidian parasite that causes diarrheal disease in many vertebrate species, including young (less than or equal to 1 month old) calves. Older calves and adult cattle are resistant to infection. In this study, newborn calves were raised in isolation from C. parvum for 1 week to 3 months before experimental challenge with the parasite. Calves orally challenged with C. parvum at 1 week of age shed oocysts in their feces and had diarrhea after challenge exposure. When these calves were rechallenged at 1 and 3 months of age, they neither shed oocysts nor had diarrhea. There was no significant increase in the mean anticryptosporidium enzyme-linked immunosorbent assay serum antibody titer in these calves following any of the challenge exposures. Calves orally inoculated with C. parvum for the first time at 1 month of age shed oocysts, had diarrhea after challenge exposure, and were resistant to rechallenge at 3 months of age. These calves had a twofold increase in serum antibody titer after the first challenge and no increase after the second challenge. Calves orally inoculated with C. parvum for the first time at 3 months of age shed oocysts, and two of seven animals had diarrhea. These calves had a 10-fold increase in serum antibody to C. parvum after exposure. This study demonstrates that calves raised in isolation from C. parvum remain susceptible to challenge until at least 3 months of age. Furthermore, within this time period, initial exposure and recovery renders calves resistant to further challenge with the parasite. The data also suggest that exposure of young calves to C. parvum may inhibit the development of a serum antibody response to the parasite. PMID:2365460

  17. Trapped solar wind noble gases, kr81/kr exposure ages and k/ar ages in apollo 11 lunar material.

    PubMed

    Eberhardt, P; Geiss, J; Graf, H; Grögler, N; Krähenbühl, U; Schwaller, H; Schwarzmüller, J; Stettler, A

    1970-01-30

    Grain size and etching experiments show that the fine lunar material contains large amounts of trapped solar wind particles. Elemental and isotopic compositions of the noble gases in solar material and in the terrestrial atmosphere are significantly different, except for the Ar(36)/ Ar(38) and the Kr isotope ratios. Exposure ages of two rocks and of the fine material are between 380 and 510 x 10(6) years. Feldspar concentrates give K/Ar ages of 3220 and 3300 x 10(6) years, significantly higher than the unseparated rock.

  18. Prenatal and childhood environmental tobacco smoke exposure and age at menarche.

    PubMed

    Ferris, Jennifer S; Flom, Julie D; Tehranifar, Parisa; Mayne, Susan T; Terry, Mary Beth

    2010-11-01

    Previous studies have reported mixed results regarding the association between age at menarche and environmental tobacco smoke exposure, both prenatally and during early childhood; however, few studies have had data available during both time periods. The present study examined whether exposure to prenatal tobacco smoke (PTS) via maternal smoking during pregnancy or childhood environmental tobacco smoke (ETS) was associated with age at menarche in a multi-ethnic birth cohort. With the uniquely available prospectively collected data on body size and growth at birth and in early life, we further examined whether the association between PTS and ETS exposure and age at menarche was mediated by these variables. From 2001 to 2006, we recruited 262 women born between 1959 and 1963 who were enrolled previously in a New York City site of the National Collaborative Perinatal Project. Mothers who smoked during pregnancy vs. those who did not were more likely to be White, younger, have more education and have lower birthweight babies. Daughters with heavy PTS exposure (≥ 20 cigarettes per day) had a later age at menarche (>12 years vs. ≤ 12 years), odds ratio (OR) =2.1 [95% confidence interval (CI) 0.9, 5.0] compared with daughters with no PTS. Daughters exposed to only childhood ETS had a later age at menarche, OR=2.1 [95% CI 1.0, 4.3], and those exposed to PTS and ETS combined had a statistically significant later age at menarche, OR=2.2 [95% CI 1.1, 4.6] compared with daughters with no PTS and no ETS. These results did not change after further adjustment for birthweight and postnatal growth suggesting that exposure to PTS and ETS is associated with later age at menarche even after considering possible relationships with growth.

  19. 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.

  20. Exposure to any antenatal corticosteroids and outcomes in preterm infants by gestational age: prospective cohort study

    PubMed Central

    Travers, Colm P; Clark, Reese H; Spitzer, Alan R; Das, Abhik; Garite, Thomas J

    2017-01-01

    Objective To determine whether exposure to any antenatal corticosteroids is associated with a lower rate of death at each gestational age at which administration is currently recommended. Design Prospective cohort study. Settings 300 participating neonatal intensive care units of the Pediatrix Medical Group in the United States. Participants 117 941 infants 23 0/7 to 34 6/7 weeks’ gestational age born between 1 January 2009 and 31 December 2013. Exposure Any antenatal corticosteroids. Main outcomes measures Death or major hospital morbidities analyzed by gestational age and exposure to antenatal corticosteroids with models adjusted for birth weight, sex, mode of delivery, and multiple births. Results Infants exposed to antenatal corticosteroids (n=81 832) had a significantly lower rate of death before discharge at each gestation 29 weeks or less, 31 weeks, and 33-34 weeks compared with infants without exposure (range of adjusted odds ratios 0.32 to 0.55). The number needed to treat with antenatal corticosteroids to prevent one death before discharge increased from six at 23 and 24 weeks’ gestation to 798 at 34 weeks’ gestation. The rate of survival without major hospital morbidity was higher among infants exposed to antenatal corticosteroids at the lowest gestations. Infants exposed to antenatal corticosteroids had lower rates of severe intracranial hemorrhage or death, necrotizing enterocolitis stage 2 or above or death, and severe retinopathy of prematurity or death compared with infants without exposure at all gestations less than 30 weeks and most gestations for infants born at 30 weeks’ gestation or later. Conclusion Among infants born from 23 to 34 weeks’ gestation, antenatal exposure to corticosteroids compared with no exposure was associated with lower mortality and morbidity at most gestations. The effect size of exposure to antenatal corticosteroids on mortality seems to be larger in infants born at the lowest gestations. PMID

  1. Peculiarities of distributions of the cosmic-ray exposure ages of H chondrite falls and finds

    NASA Technical Reports Server (NTRS)

    Alexeev, V. A.

    1993-01-01

    Well known peak in the distribution of the cosmic-ray exposure ages of H chondrites at 6-7 My can be employed as mark in comparison of different populations of H chondrites. It is found the age corresponding to maximum of peak for non-Antarctic falls is higher by (15+/-5) percent of this for non-Antarctic finds. Antarctic H chondrites occupy intermediate position. This effect is probably due to process of weathering.

  2. Does pupil constriction under blue and green monochromatic light exposure change with age?

    PubMed Central

    Daneault, Véronique; Vandewalle, Gilles; Hébert, Marc; Teikari, Petteri; Mure, Ludovic S.; Doyon, Julien; Gronfier, Claude; Cooper, Howard M.; Dumont, Marie; Carrier, Julie

    2017-01-01

    Many non-visual functions are regulated by light through a photoreceptive system involving melanopsin-expressing retinal ganglion cells that are maximally sensitive to blue light. Several studies have suggested that the ability of light to modulate circadian entrainment and to induce acute effects on melatonin secretion, subjective alertness and gene expression, decreases during aging, particularly for blue light. This could contribute to the documented changes in sleep and circadian regulatory processes with aging. However, age-related modification in the impact of light on steady-state pupil constriction, which regulates the amount of light reaching the retina, is not demonstrated. We measured pupil size in 16 young (22.8±4y) and 14 older (61±4.4y) healthy subjects during 45s exposures to blue (480nm) and green (550nm) monochromatic lights at low (7×1012 photons/cm2/s), medium (3×1013 photons/cm2/s), and high (1014 photons/cm2/s) irradiance levels. Results showed that young subjects had consistently larger pupils than older subjects, for dark adaptation and during all light exposures. Steady-state pupil constriction was greater under blue than green light exposure in both age groups and increased with increasing irradiance. Surprisingly, when expressed in relation to baseline pupil size, no significant age-related differences were observed in pupil constriction. The observed reduction in pupil size in older individuals, both in darkness and during light exposure, may reduce retinal illumination and consequently affect non-visual responses to light. The absence of a significant difference between age groups for relative steady-state pupil constriction suggests that other factors such as tonic, sympathetic control of pupil dilation, rather than light sensitivity per se, account for the observed age difference in pupil size regulation. Compared to other nonvisual functions, the light sensitivity of steady-state pupil constriction appears to remain relatively

  3. Prenatal ethanol exposure differentially affects hippocampal neurogenesis in the adolescent and aged brain.

    PubMed

    Gil-Mohapel, J; Titterness, A K; Patten, A R; Taylor, S; Ratzlaff, A; Ratzlaff, T; Helfer, J; Christie, B R

    2014-07-25

    Exposure to ethanol in utero is associated with a myriad of sequelae for the offspring. Some of these effects are morphological in nature and noticeable from birth, while others involve more subtle changes to the brain that only become apparent later in life when the individuals are challenged cognitively. One brain structure that shows both functional and structural deficits following prenatal ethanol exposure is the hippocampus. The hippocampus is composed of two interlocking gyri, the cornu ammonis (CA) and the dentate gyrus (DG), and they are differentially affected by prenatal ethanol exposure. The CA shows a more consistent loss in neuronal numbers, with different ethanol exposure paradigms, than the DG, which in contrast shows more pronounced and consistent deficits in synaptic plasticity. In this study we show that significant deficits in adult hippocampal neurogenesis are apparent in aged animals following prenatal ethanol exposure. Deficits in hippocampal neurogenesis were not apparent in younger animals. Surprisingly, even when ethanol exposure occurred in conjunction with maternal stress, deficits in neurogenesis did not occur at this young age, suggesting that the capacity for neurogenesis is highly conserved early in life. These findings are unique in that they demonstrate for the first time that deficits in neurogenesis associated with prenatal ethanol consumption appear later in life.

  4. Prenatal Methamphetamine Exposure and Inhibitory Control among Young School-Age Children

    PubMed Central

    Derauf, Chris; LaGasse, Linda L.; Smith, Lynne M.; Newman, Elana; Shah, Rizwan; Neal, Charles; Arria, Amelia; Huestis, Marilyn A.; Grotta, Sheri Della; Dansereau, Lynne M.; Lin, Hai; Lester, Barry M.

    2012-01-01

    Objective To examine the association between prenatal methamphetamine exposure and inhibitory control in 66 month old children followed since birth in the multicenter, longitudinal Infant Development, Environment and Lifestyle Study. Study design The sample included 137 children with prenatal methamphetamine exposure and 130 comparison children, matched for race, birth weight, maternal education and type of insurance. Inhibitory control, an executive function related to emotional and cognitive control, was assessed using a computerized Stroop-like task developed for young children. Hierarchical linear modeling tested the relationship between the extent (heavy, some and no use) of prenatal methamphetamine exposure and accuracy and reaction time outcomes, adjusting for prenatal exposure to alcohol, tobacco and marijuana, age, sex, socioeconomic status, caregiver IQ and psychological symptoms, child protective services report of physical or sexual abuse, and site. Results In adjusted analyses, heavy prenatal methamphetamine exposure was related to reduced accuracy in both the incongruent and mixed conditions on the Stroop task. Caregiver psychological symptoms and Child Protective Services (CPS) report of physical or sexual abuse were associated with reduced accuracy in the incongruent and mixed, and incongruent conditions, respectively. Conclusions Heavy prenatal methamphetamine exposure, along with caregiver psychological distress and child maltreatment, is related to subtle deficits in inhibitory control during the early school-aged years. PMID:22424953

  5. Long-term ambient particle exposures and blood DNA methylation age: findings from the VA normative aging study

    PubMed Central

    Nwanaji-Enwerem, Jamaji C.; Colicino, Elena; Trevisi, Letizia; Kloog, Itai; Just, Allan C.; Shen, Jincheng; Brennan, Kasey; Dereix, Alexandra; Hou, Lifang; Vokonas, Pantel; Schwartz, Joel; Baccarelli, Andrea A.

    2016-01-01

    Background Ambient particles have been shown to exacerbate measures of biological aging; yet, no studies have examined their relationships with DNA methylation age (DNAm-age), an epigenome-wide DNA methylation based predictor of chronological age. Objective We examined the relationship of DNAm-age with fine particulate matter (PM2.5), a measure of total inhalable particle mass, and black carbon (BC), a measure of particles from vehicular traffic. Methods We used validated spatiotemporal models to generate 1-year PM2.5 and BC exposure levels at the addresses of 589 older men participating in the VA Normative Aging Study with 1–3 visits between 2000 and 2011 (n = 1032 observations). Blood DNAm-age was calculated using 353 CpG sites from the Illumina HumanMethylation450 BeadChip. We estimated associations of PM2.5 and BC with DNAm-age using linear mixed effects models adjusted for age, lifestyle/environmental factors, and aging-related diseases. Results After adjusting for covariates, a 1-µg/m3 increase in PM2.5 (95% CI: 0.30, 0.75, P<0.0001) was significantly associated with a 0.52-year increase in DNAm-age. Adjusted BC models showed similar patterns of association (β = 3.02, 95% CI: 0.48, 5.57, P = 0.02). Only PM2.5 (β = 0.54, 95% CI: 0.24, 0.84, P = 0.0004) remained significantly associated with DNAm-age in two-particle models. Methylation levels from 20 of the 353 CpGs contributing to DNAm-age were significantly associated with PM2.5 levels in our two-particle models. Several of these CpGs mapped to genes implicated in lung pathologies including LZTFL1, PDLIM5, and ATPAF1. Conclusion Our results support an association of long-termambient particle levels with DNAm-age and suggest that DNAm-age is a biomarker of particle-related physiological processes. PMID:27453791

  6. Last Glacial Maximum Dated by Means of 10Be in the Maritime Alps (Italy)

    NASA Astrophysics Data System (ADS)

    Granger, D. E.; Spagnolo, M.; Federici, P.; Pappalardo, M.; Ribolini, A.; Cyr, A. J.

    2006-12-01

    Relatively few exposure dates of LGM moraines boulders are available for the European Alps, and none on the southern flank. Ponte Murato (PM) is a frontal moraine at 860 m asl in the Gesso Basin (Maritime Alps, SW European Alps). The PM moraine dams the 157 km2 Gesso della Barra Valley and it represents the lowermost frontal moraine of the entire Gesso Valley, near the outlet of the valley in the Po Plain. Its ELA, determined from the paleo- shape of the supposed Gesso della Barra glacier, is 1746 m asl. Tetti Bandito (TB) is a small and badly preserved glacial deposit, tentatively attributed to a lateral-frontal moraine, that is positioned 5 km downvalley from the PM deposit at 800 m asl. There are no other glacial deposits downvalley from the TB moraine in the Gesso Basin or farther NE in the piedmont region of the upper Po Plain. Boulders sampled on the PM and on the TB moraine crests gave a 10Be cosmogenic age of respectively 16300 ± 880 ka (average value) and 18798 ± 973 ka. This result constrains the PM frontal moraine within the LGM interval but also suggests that the maximum expansion of the Gesso Basin glacier was more downvalley at some point during the last glaciation. If the TB is a lateral-frontal moraine as supposed, the two TB and PM moraines would represent the outer and inner moraine crests of the same LGM stadial, with the outer moraine much less pronounced than the inner moraine, similarly to the maximalstand and the hochstand described in the Eastern Alps (Van Husen, 1997). Within this perspective, the PM and TB dates are consistent with a European Alps LGM corresponding to MIS 2 (Ivy-Ochs et al., 2004). This study of the Maritime Alps moraines is also in agreement with the Upper Würm climatic theory (Florineth and Schlüchter, 2000) of a stronger influence of the W and SW incoming humid airflows in the European Alps, differently from the nearby Vosges and Pyrenees mountain chains where more dry conditions were probably responsible for a very

  7. An episode of rapid bedrock channel incision during the last glacial cycle, measured with 10Be

    USGS Publications Warehouse

    Reusser, L.; Bierman, P.; Pavich, M.; Larsen, J.; Finkel, R.

    2006-01-01

    We use 10Be to infer when, how fast, and why the Susquehanna River incised through bedrock along the U.S. Atlantic seaboard, one of the world's most prominent and ancient passive margins. Although the rate at which large rivers incise rock is a fundamental control on the development of landscapes, relatively few studies have directly measured how quickly such incision occurs either in tectonically active environments or along passive margins. Exposure ages of fluvially carve d, bedrock strath terraces, preserved along the lower Susquehanna River, demonstrate that even along a passive margin, large rivers are capable of incising through rock for short periods of time at rates approaching those recorded in tectonically active regions, such as the Himalayas. Over eighty samples, collected along and between three prominent levels of strath terraces within Holtwood Gorge, indicate that the Susquehanna River incised more than 10 meters into the Appalachian Piedmont during the last glacial cycle. Beginning ???36 ka, incision rates increased dramatically, and remained elevated until ???14 ka. The northern half of the Susquehanna basin was glaciated during the late Wisconsinan; however, similar rates and timing of incision occurred in the unglaciated Potomac River basin immediately to the south. The concurrence of incision periods on both rivers suggests that glaciation and associated meltwater were not the primary drivers of incision. Instead, it appears that changing climatic conditions during the late Pleistocene promoted an increase in the frequency and magnitude of flood events capable of exceeding thresholds for rock detachment and bedrock erosion, thus enabling a short-lived episode of rapid incision into rock. Although this study has constraine d the timing and rate of bedrock incision along the largest river draining the Atlantic passive margin, the dates alone cannot explain fully why, or by what processes, this incision occurred. However, cosmogenic dating offers

  8. 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.; 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. M.; Navarro-Gonzalez, R.; Schwenzer, S. P.; Steele, A.; Stolper, E. M.; Sumner, D. Y.; Vaniman, D.; Vasavada, A.; Williford, K.; Wimmer-Schweingruber, R. F.

    2014-01-01

    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 3He, 21Ne, and 36Ar yield concordant surface exposure ages of 78 T 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.

  9. 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.

  10. TOXICOGENOMIC ANALYSIS OF TOLUENE EXPOSURE AT 3 AGES IN BROWN NORWAY RATS.

    EPA Science Inventory

    A major concern in assessing toxicity to environmental exposures is differential

    susceptibility in subsets of the population. Aging adults, who comprise the fastest

    growing segment of the population, may possess a greater sensitivity due to changes in

    metabol...

  11. The Association between Prenatal Cocaine Exposure and Physiological Regulation at 13 Months of Age

    ERIC Educational Resources Information Center

    Schuetze, Pamela; Eiden, Rina D.; Danielewicz, Susan

    2009-01-01

    Background: This study examined the association between prenatal cocaine exposure (PCE) and autonomic regulation at 13 months of age. Methods: Measures of respiratory sinus arrhythmia (RSA) were obtained from 156 (79 exposed, and 77 nonexposed) infants during baseline and during tasks designed to elicit positive (PA) and negative affect (NA).…

  12. A Case Series of Marijuana Exposures in Pediatric Patients Less than 5 Years of Age

    ERIC Educational Resources Information Center

    Wang, George Sam; Narang, Sandeep K.; Wells, Kathryn; Chuang, Ryan

    2011-01-01

    Objective: In Colorado, there has been a large increase in medical marijuana dispensaries and licenses for the use of medical marijuana over the past year. This is a retrospective case series of marijuana exposures that have presented to the emergency department (ED) in children less than 5 years of age. Methods: We performed a retrospective chart…

  13. Effects of Age of English Exposure, Current Input/Output, and Grade on Bilingual Language Performance

    ERIC Educational Resources Information Center

    Bedore, Lisa M.; Pena, Elizabeth D.; Griffin, Zenzi M.; Hixon, J. Gregory

    2016-01-01

    This study evaluates the effects of Age of Exposure to English (AoEE) and Current Input/Output on language performance in a cross-sectional sample of Spanish-English bilingual children. First- (N = 586) and third-graders (N = 298) who spanned a wide range of bilingual language experience participated. Parents and teachers provided information…

  14. TOXICITY PATHWAY ANALYSIS IN AGING BROWN NORWAY RAT BRAIN FOLLOWING ACUTE TOLUENE EXPOSURE

    EPA Science Inventory

    The influence of aging on susceptibility to environmental stressors is poorly understood. To investigate the contribution of different life stages on response to toxicants, we examined the effects of acute exposure by oral gavage of the volatile organic solvent toluene (0.00, 0.3...

  15. Maternal occupational exposure to polycyclic aromatic hydrocarbons and small for gestational age offspring

    PubMed Central

    Langlois, Peter H.; Hoyt, Adrienne T.; Desrosiers, Tania A.; Lupo, Philip J.; Lawson, Christina C.; Waters, Martha A.; Rocheleau, Carissa M.; Shaw, Gary M.; Romitti, Paul A.; Gilboa, Suzanne M.; Malik, Sadia

    2015-01-01

    Objectives While some of the highest maternal exposures to polycyclic aromatic hydrocarbons (PAHs) occur in the workplace, there is only one previous study of occupational PAH exposure and adverse pregnancy outcomes. We sought to extend this literature using interview data combined with detailed exposure assessment. Methods Data for 1997–2002 were analysed from mothers of infants without major birth defects in the National Birth Defects Prevention Study, a large population-based case-control study in the USA. Maternal telephone interviews yielded information on jobs held in the month before conception through delivery. From 6252 eligible control mothers, 2803 completed the interview, had a job, met other selection criteria, and were included in the analysis. Two industrial hygienists independently assessed occupational exposure to PAHs from the interview and reviewed results with a third to reach consensus. Small for gestational age (SGA) was the only adverse pregnancy outcome with enough exposed cases to yield meaningful results. Logistic regression estimated crude and adjusted ORs. Results Of the 2803 mothers, 221 (7.9%) had infants who were SGA. Occupational PAH exposure was found for 17 (7.7%) of the mothers with SGA offspring and 102 (4.0%) of the remaining mothers. Almost half the jobs with exposure were related to food preparation and serving. After adjustment for maternal age, there was a significant association of occupational exposure with SGA (OR=2.2, 95% CI 1.3 to 3.8). Conclusions Maternal occupational exposure to PAHs was found to be associated with increased risk of SGA offspring. PMID:24893704

  16. The granite tors of Dartmoor, Southwest England: rapid and recent emergence revealed by Late Pleistocene cosmogenic apparent exposure ages

    NASA Astrophysics Data System (ADS)

    Gunnell, Yanni; Jarman, David; Braucher, Régis; Calvet, Marc; Delmas, Magali; Leanni, Laetitia; Bourlès, Didier; Arnold, Maurice; Aumaître, Georges; Keddaouche, Karim

    2013-02-01

    Dartmoor, in SW England, is a classic periglaciated granite upland adorned with a population of over 150 tors. The origin of the tors has been controversial, but their emergence by differentiation after stripping of regolith during Pleistocene cold phases is accepted. However, their actual age has been unknown, with possible scenarios ranging from preservation since the early Middle Pleistocene to relatively short-lived landforms in a maritime climate with high denudation rates. The latter is now supported by 32 cosmogenic surface exposure dates from 28 tors across the whole upland. The distribution of apparent 10Be ages peaks strongly in the Middle Devensian (36-50 ka), which with corrections for weathering and limited ice shielding could be interpreted as Early Devensian. These ages are much younger than those found for three glacially unmodified Cairngorms tors, and somewhat younger even than glacially modified Cairngorms tors. The dates show little spatial variation. Although an ice cap has now been modelled in the heart of northern Dartmoor, tors here are of median age, suggesting that ice cover sufficient to shield tors from incoming radiation was of short duration. The few younger tor ages support the idea of continuing landform instability across the landscape, with weathering flakes redeveloping soon after inferred loss of top pillows by gelifraction or gravitational toppling. The few older tor ages have no systematic explanation, and may indicate inheritance from an earlier cycle of bedrock near-exposure. Since most tors are modest in height (typically 2-5 m), volumetrically insignificant, and often in advanced stages of disintegration, the general impression is that they are evanescent features, which emerge and quickly disappear during every Pleistocene climatic downturn. Tor populations may thus flicker across the landscape rather randomly over the Quaternary. The remarkably consistent age of the present tor population could be associated with a

  17. Interaction Between Age and Exposure to 56Fe Particles on Behavior and Neurochemistry

    NASA Astrophysics Data System (ADS)

    Shukitt-Hale, B.; Carey, A. N.; Rabin, B. M.; Joseph, J. A.

    Previous research has shown that exposure to HZE particles and protons which will be encountered on long-term space missions can adversely affect the ability of rats to perform a variety of behavioral tasks This outcome has implications for an astronaut s ability to successfully complete requirements associated with these missions It has also been found that irradiation can lead to increases in oxidative stress similar to that seen in the aging brain Given that astronauts are often middle-aged or older it is important to determine if their age puts them at higher risk for the potentially hazardous effects of exposure to HZE particles Therefore we exposed young and old rats to either 1 or 2Gy of 56 Fe irradiation and evaluated performance in a spatial learning and memory task in addition to examining levels of dopamine DA release from superfused striatal slices Results indicated that exposure to 56 Fe particles can produce alterations in behavior and signaling and that these alterations may be more apparent in older organisms which suggests that the aging brain may be more susceptible to the deleterious effects of irradiation on performance Therefore age may be a factor for consideration in planning long-term missions into space Supported by NASA Grants NAG9-1190 and NAG9-1529

  18. Interaction between age and exposure to 56Fe particles on behavior and neurochemistry

    NASA Astrophysics Data System (ADS)

    Carey, Amanda N.; Shukitt-Hale, Barbara; Rabin, Bernard M.; Joseph, James A.

    Previous research has shown that exposure to HZE particles, which will be encountered on long-term space missions, can adversely affect the ability of rats to perform a variety of behavioral tasks. This outcome has implications for an astronaut’s ability to successfully complete requirements associated with these missions. It has also been found that irradiation can lead to increases in oxidative stress, similar to that seen in the aging brain. Given that astronauts are often middle-aged or older it is important to determine if their age puts them at higher risk for the potentially hazardous effects of exposure to HZE particles. Therefore, we exposed young and old rats to either 1 or 2 Gy of 56Fe irradiation and evaluated performance in a spatial learning and memory task, in addition to examining levels of dopamine (DA) release from superfused striatal slices. Results indicated that exposure to 56Fe particles can produce alterations in behavior and neuronal signaling and that these alterations may be more apparent in older organisms, a finding which suggests that the aging brain may be more susceptible to the deleterious effects of irradiation on performance. Therefore, age may be a factor for consideration in planning long-term missions into space.

  19. Maternal Exposure to Polybrominated and Polychlorinated Biphenyls: Infant Birth Weight and Gestational Age

    PubMed Central

    Givens, Marjory L.; Small, Chanley M.; Terrell, Metrecia L.; Cameron, Lorraine L.; Blanck, Heidi Michels; Tolbert, Paige E.; Rubin, Carol; Henderson, Alden K.; Marcus, Michele

    2007-01-01

    Understanding the influence of maternal exposures on gestational age and birth weight is essential given that pre-term and/or low birth weight infants are at risk for increased mortality and morbidity. We performed a retrospective analysis of a cohort exposed to polybrominated biphenyls (PBB) through accidental contamination of cattle feed and polychlorinated biphenyls (PCB) through residual contamination in the geographic region. Our study population consisted of 444 mothers and their 899 infants born between 1975 and 1997. Using restricted maximum likelihood estimation, no significant association was found between estimated maternal serum PBB at conception or enrollment PCB levels and gestational age or infant birth weight in unadjusted models or in models that adjusted for maternal age, smoking, parity, infant gender, and decade of birth. For enrollment maternal serum PBB, no association was observed for gestational age. However, a negative association with high levels of enrollment maternal serum PBB and birth weight was suggested. We also examined the birth weight and gestational age among offspring of women with the highest (10%) PBB or PCB exposure, and observed no significant association. Because brominated compounds are currently used in consumer products and therefore, are increasingly prevalent in the environment, additional research is needed to better understand the potential relationship between in utero exposure to brominated compounds and adverse health outcomes. PMID:17617441

  20. Elbow joint disorders in relation to vibration exposure and age in stone quarry workers.

    PubMed

    Sakakibara, H; Suzuki, H; Momoi, Y; Yamada, S

    1993-01-01

    Elbow joint disorders were studied in relation to vibration exposure and age in 74 male stone quarry workers who operated mainly chipping hammers and sometimes rock drills. They were examined for range of active motion in elbow extension and flexion, and by means of radiographs of the elbow joint. Effects of age and vibratory tool operation on the elbow joint were statistically estimated using multiple regression analysis. In the analysis of all subjects, including those aged over 60 years, age was significantly related to the range of motion in extension and to radiographic changes in both elbows, and the duration of vibratory tool operation was associated with the range of right elbow flexion. Among subjects under the age of 60 years, duration of vibratory tool operation showed a significant dose-effect relationship to the range of flexion and radiographic changes in the right elbow, but there was no significant relationship with age. The present results suggest that the operation of chipping hammers and rock drills contributes to elbow joint disorders or osteoarthrosis, even when the effect of age is taken into account. Besides vibration exposure, it may be necessary to consider various loads on the elbow joint such as firmly grasping and pressing the tool against stones with the arm bent at about 90 degrees, and carrying stones.

  1. Effects of age and exposure to heavy particles on a behavioral measure of anxiety

    NASA Astrophysics Data System (ADS)

    Rabin, B. M.; Joseph, J. A.; Shukitt-Hale, B.; Carrihill-Knoll, K. L.; Carey, A.; Foster, B. C.

    On forthcoming exploratory class missions astronauts will be expected to function in novel and possibly dangerous environments This requirement may produce anticipatory fear or anxiety Previous research has shown that exposure to HZE particles such as those experienced on missions beyond the protection provided by the magnetic shield of the earth can affect the performance of the organism on a variety of tasks In addition research has shown that there is an interaction between age and exposure to heavy particles on a variety of behavioral tasks such that older organisms are more susceptible to the deleterious effects of irradiation Because there are changes in exploration-induced anxiety as a function of age it is possible that exposure to HZE particles will also affect a middle-aged astronaut s ability to respond appropriately in anxiety producing situations The present experiment utilized the elevated plus-maze to evaluate the effects of age and exposure to HZE particle radiation on anxiety Fischer-344 rats 2 7 12 and 16 months of age at the time of irradiation were exposed to 56 Fe particles 1 GeV n 0 25-2 00 Gy in the NASA Space Radiation Laboratory at Brookhaven National Laboratory Control rats at each age were not irradiated At the time of testing the rats were 3- 11- 13- and 20-months old respectively Anxiety was studied using an elevated plus-maze The maze is composed of four arms in the shape of a sign placed 90 cm above the floor Two of the arms are enclosed and two of the arms are open The amount of

  2. Phosphatidylserine exposure and red cell viability in red cell aging and in hemolytic anemia

    PubMed Central

    Boas, Franz Edward; Forman, Linda; Beutler, Ernest

    1998-01-01

    Phosphatidylserine (PS) normally localizes to the inner leaflet of cell membranes but becomes exposed in abnormal or apoptotic cells, signaling macrophages to ingest them. Along similar lines, it seemed possible that the removal of red cells from circulation because of normal aging or in hemolytic anemias might be triggered by PS exposure. To investigate the role of PS exposure in normal red cell aging, we used N-hydroxysuccinimide-biotin to tag rabbit red cells in vivo, then used phycoerythrin-streptavidin to label the biotinylated cells, and annexin V-fluorescein isothiocyanate (FITC) to detect the exposed PS. Flow cytometric analysis of these cells drawn at 10-day intervals up to 70 days after biotinylation indicated that older, biotinylated cells expose more PS. Furthermore, our data match a simple model of red cell senescence that assumes both an age-dependent destruction of senescent red cells preceded by several hours of PS exposure and a random destruction of red cells without PS exposure. By using this model, we demonstrated that the exposure of PS parallels the rate at which biotinylated red cells are removed from circulation. On the other hand, using an annexin V-FITC label and flow cytometry demonstrates that exposed PS does not cause the reduced red cell life span of patients with hemolytic anemia, with the possible exception of those with unstable hemoglobins or sickle cell anemia. Thus, in some cases PS exposure on the cell surface may signal the removal of red cells from circulation, but in other cases some other signal must trigger the sequestration of cells. PMID:9501218

  3. Cognitive deficits at age 22 years associated with prenatal exposure to methylmercury

    PubMed Central

    Debes, Frodi; Weihe, Pal; Grandjean, Philippe

    2015-01-01

    Prenatal exposure to mercury has been associated with adverse effects on child neurodevelopment. The present study aims to determine the extent to which methylmercury-associated cognitive deficits persist into adult age. In a Faroese birth cohort originally formed in 1986–1987 (N=1,022), prenatal methylmercury exposure was assessed in terms of the mercury concentration in cord blood and maternal hair. Clinical examinations of 847 cohort members at age 22 years were carried out in 2008–2009 using a panel of neuropsychological tests that reflected major functional domains. Subjects with neurological and psychiatric diagnoses were excluded from the data analysis, thus leaving 814 subjects. Multiple regression analysis included covariates previously identified for adjustment. Deficits in Boston Naming Test and other tests of verbal performance were significantly associated with the cord-blood mercury concentration. Deficits were also present in all other tests applied, although most were not statistically significant. Structural equation models were developed to ascertain the possible differences in vulnerability of specific functional domains and the overall association with general intelligence. In models for individual domains, all of them showed negative associations, with crystallized intelligence being highly significant. A hierarchical model for general intelligence based on all domains again showed a highly significant negative association with the exposure, with an approximate deficit that corresponds to about 2.2 IQ points at a 10-fold increased prenatal methylmercury exposure. Thus, although the cognitive deficits observed were smaller than at examinations at younger ages, maternal seafood diets were associated with adverse effects in this birth cohort at age 22 years. The deficits affected major domains of brain functions as well as general intelligence. Thus, prenatal exposure to this marine contaminant appears to cause permanent adverse effects on

  4. Bedtime and evening light exposure influence circadian timing in preschool-age children: A field study

    PubMed Central

    Akacem, Lameese D.; Wright, Kenneth P.; LeBourgeois, Monique K.

    2016-01-01

    Light exposure and sleep timing are two factors that influence inter-individual variability in the timing of the human circadian clock. The aim of this study was to quantify the degree to which evening light exposure predicts variance in circadian timing over and above bedtime alone in preschool children. Participants were 21 children ages 4.5–5.0 years (4.7 ± 0.2 years; 9 females). Children followed their typical sleep schedules for 4 days during which time they wore a wrist actigraph to assess sleep timing and a pendant light meter to measure minute-by-minute illuminance levels in lux. On the 5th day, children participated in an in-home dim-light melatonin onset (DLMO) assessment. Light exposure in the 2 h before bedtime was averaged and aggregated across the 4 nights preceding the DLMO assessment. Mean DLMO and bedtime were 19:22 ± 01:04 and 20:07 ± 00:46, respectively. Average evening light exposure was 710.1 ± 1418.2 lux. Children with later bedtimes (lights-off time) had more delayed melatonin onset times (r=0.61, p=0.002). Evening light exposure was not independently associated with DLMO (r=0.32, p=0.08); however, a partial correlation between evening light exposure and DLMO when controlling for bedtime yielded a positive correlation (r=0.46, p=0.02). Bedtime explained 37.3% of the variance in the timing of DLMO, and evening light exposure accounted for an additional 13.3% of the variance. These findings represent an important step in understanding factors that influence circadian phase in preschool-age children and have implications for understanding a modifiable pathway that may underlie late sleep timing and the development of evening settling problems in early childhood. PMID:28042611

  5. Potentials and pitfalls of depth profile (10Be), burial isochron (26Al/10Be) and palaeomagnetic techniques for dating Early Pleistocene terrace deposits of the Moselle valley (Germany)

    NASA Astrophysics Data System (ADS)

    Rixhon, Gilles; Cordier, Stéphane; May, Simon Matthias; Kelterbaum, Daniel; Szemkus, Nina; Keulertz, Rebecca; Dunai, Tibor; Binnie, Steven; Hambach, Ulrich; Scheidt, Stephanie; Brueckner, Helmut

    2016-04-01

    Throughout the river network of the Rhenish Massif the so-called main terraces complex (MTC) forms the morphological transition between a wide upper palaeovalley and a deeply incised lower valley. The youngest level of this complex (YMT), directly located at the edge of the incised valley, represents a dominant geomorphic feature; it is often used as a reference level to identify the beginning of the main middle Pleistocene incision episode (Demoulin & Hallot, 2009). Although the main terraces are particularly well preserved in the lower Moselle valley, a questionable age of ca. 800 ka is assumed for the YMT, mainly based on the uncertain extrapolation of controversially interpreted palaeomagnetic data obtained in the Rhine valley. In this study, we applied terrestrial cosmogenic nuclide (TCN) dating (10Be/26Al) and palaeomagnetic dating to Moselle fluvial sediments of the MTC. To unravel the spatio-temporal characteristics of the Pleistocene evolution of the valley, several sites along the lower Moselle were sampled following two distinct TCN dating strategies: depth profiles where the original terrace (palaeo-) surface is well preserved and did not experience a major post-depositional burial (e.g., loess cover); and the isochron technique, where the sediment thickness exceeds 4.5-5 m. One terrace deposit was sampled for both approaches (reference site). In addition, palaeomagnetic sampling was systematically performed in each terrace sampled for TCN measurements. The TCN dating techniques show contrasting results for our reference site. Three main issues are observed for the depth profile method: (i) an inability of the modeled profile to constrain the 10Be concentration of the uppermost sample; (ii) an overestimated density value as model output; and (iii) a probable concentration steady state of the terrace deposits. By contrast, the isochron method yields a burial age estimate of 1.26 +0.29/-0.25 Ma, although one sample showed a depleted 26Al/10Be ratio

  6. Neurobehavioral deficits at age 7 years associated with prenatal exposure to toxicants from maternal seafood diet

    PubMed Central

    Grandjean, Philippe; Weihe, Pal; Nielsen, Flemming; Heinzow, Birger; Debes, Frodi; Budtz-Jørgensen, Esben

    2012-01-01

    To determine the possible neurotoxic impact of prenatal exposure to polychlorinated biphenyls (PCBs), we analyzed banked cord blood from a Faroese birth cohort for PCBs. The subjects were born in 1986–1987, and 917 cohort members had completed a series of neuropsychological tests at age 7 years. Major PCB congeners (118, 138, 153, and 180), the calculated total PCB concentration, and the PCB exposure estimated in a structural equation model showed weak associations with test deficits, with statistically significant negative associations only with the Boston Naming test. Likewise, neither hexachlorobenzene nor p,p'-dichlorodiphenyldichloroethylene showed clear links to neurobehavioral deficits. Thus, these associations were much weaker than those associated with the cord-blood mercury concentration, and adjustment for mercury substantially attenuated the regression coefficients for PCB exposure. When the outcomes were joined into motor and verbally mediated functions in a structural equation model, the PCB effects remained weak and virtually disappeared after adjustment for methylmercury exposure, while mercury remained statistically significant. Thus, in the presence of elevated methylmercury exposure, PCB neurotoxicity may be difficult to detect, and PCB exposure does not explain the methylmercury neurotoxicity previously reported in this cohort. PMID:22705177

  7. Neurobehavioral deficits at age 7 years associated with prenatal exposure to toxicants from maternal seafood diet.

    PubMed

    Grandjean, Philippe; Weihe, Pal; Nielsen, Flemming; Heinzow, Birger; Debes, Frodi; Budtz-Jørgensen, Esben

    2012-07-01

    To determine the possible neurotoxic impact of prenatal exposure to polychlorinated biphenyls (PCBs), we analyzed banked cord blood from a Faroese birth cohort for PCBs. The subjects were born in 1986-1987, and 917 cohort members had completed a series of neuropsychological tests at age 7 years. Major PCB congeners (118, 138, 153, and 180), the calculated total PCB concentration, and the PCB exposure estimated in a structural equation model showed weak associations with test deficits, with statistically significant negative associations only with the Boston Naming test. Likewise, neither hexachlorobenzene nor p,p'-dichlorodiphenyldichloroethylene showed clear links to neurobehavioral deficits. Thus, these associations were much weaker than those associated with the cord-blood mercury concentration, and adjustment for mercury substantially attenuated the regression coefficients for PCB exposure. When the outcomes were joined into motor and verbally mediated functions in a structural equation model, the PCB effects remained weak and virtually disappeared after adjustment for methylmercury exposure, while mercury remained statistically significant. Thus, in the presence of elevated methylmercury exposure, PCB neurotoxicity may be difficult to detect, and PCB exposure does not explain the methylmercury neurotoxicity previously reported in this cohort.

  8. Prenatal marijuana and alcohol exposure and academic achievement at age 10.

    PubMed

    Goldschmidt, Lidush; Richardson, Gale A; Cornelius, Marie D; Day, Nancy L

    2004-01-01

    The effects of prenatal marijuana and alcohol exposure on school achievement at 10 years of age were examined. Women were interviewed about their substance use at the end of each trimester of pregnancy, at 8 and 18 months, and at 3, 6, 10, 14, and 16 years. The women were of lower socioeconomic status, high-school-educated, and light-to-moderate users of marijuana and alcohol. The sample was equally divided between Caucasian and African-American women. At the 10-year follow-up, the effects of prenatal exposure to marijuana or alcohol on the academic performance of 606 children were assessed. Exposure to one or more marijuana joints per day during the first trimester predicted deficits in Wide Range Achievement Test-Revised (WRAT-R) reading and spelling scores and a lower rating on the teachers' evaluations of the children's performance. This relation was mediated by the effects of first-trimester marijuana exposure on the children's depression and anxiety symptoms. Second-trimester marijuana use was significantly associated with reading comprehension and underachievement. Exposure to alcohol during the first and second trimesters of pregnancy predicted poorer teachers' ratings of overall school performance. Second-trimester binge drinking predicted lower reading scores. There was no interaction between prenatal marijuana and alcohol exposure. Each was an independent predictor of academic performance.

  9. Cosmic ray exposure ages of features and events at the Apollo landing sites

    NASA Technical Reports Server (NTRS)

    Arvidson, R.; Crozaz, G.; Drozd, R. J.; Hohenberg, C. M.; Morgan, C. J.

    1975-01-01

    Cosmic-ray exposure ages of lunar samples have been used to date surface features related to impact cratering and downslope movement of material. Only when multiple samples related to a feature have the same rare-gas exposure age or when a single sample has the same Kr-81 -Kr and track-exposure age can a feature be considered as reliably dated. Based on these criteria, there are only five well-dated lunar features: Cone Crater (Apollo 14), 26 m.y,; North Ray Crater (Apollo 16), 50 m.y.; South Ray Crater (Apollo 16), 2 m.y.; the emplacement of the Station 6 boulders (Apollo 17), 22 m.y.; and the emplacement of the Station 7 boulder (Apollo 17), 28 m.y. Other features are tentatively dated or have limits set on their ages: Bench Crater (Apollo 12), upper limit of 99 m.y.; Baby Ray Crater (Apollo 16), upper limit of 2 m.y.; Shorty Crater (Apollo 17), approximately 30 m.y.; Camelot Crater (Apollo 17) upper limit of 140 m.y.; the emplacement of the Station 2 boulder 1 (Apollo 17), 45 to 55 m.y.; and the slide which generated the light mantle (Apollo 17), lower limit of 50 m.y.

  10. The effect of brief neonatal exposure to cows' milk on atopic symptoms up to age 5

    PubMed Central

    de Jong, M H; Scharp-Van, D; Aalberse, R; Heymans, H; Brunekreef, B

    2002-01-01

    Aims: To determine the effect of brief early exposure to cows' milk on the expression of atopy during the first five years of life. Methods: Follow up analysis of a double blind, placebo controlled, randomised feeding intervention trial (BOKAAL study). Subjects were 1108 children from 1533 initially randomised breast fed neonates in the Netherlands. Atopic disease and prevalence of allergic symptoms at age 1, 2, and 5, and specific IgE at age 1 and 5 were determined. Results: Atopic disease in the first year was found in 10.0% (cows' milk) versus 9.3% (placebo) of the children, with a relative risk (RR) of 1.07. No differences were found in the second year either. At age 5, atopic disease was found in 26.3% (cows' milk) versus 25.0% (placebo), RR 1.05. There was no difference in the prevalence of allergic symptoms. Specific IgE to cows' milk (RAST positive 2+ or more) was 5.8% (cows' milk) versus 4.1% (placebo) at age 1 (RR 1.43), and 5.3% versus 3.0% at age 5 (RR 1.77). There was no difference in sensitisation to other common allergens between the two groups. Conclusion: Early, brief exposure to cows' milk in breast fed children is not associated with atopic disease or allergic symptoms up to age 5. PMID:11970933

  11. Estimating dose rates to organs as a function of age following internal exposure to radionuclides

    SciTech Connect

    Leggett, R.W.; Eckerman, K.F.; Dunning, D.E. Jr.; Cristy, M.; Crawford-Brown, D.J.; Williams, L.R.

    1984-03-01

    The AGEDOS methodology allows estimates of dose rates, as a function of age, to radiosensitive organs and tissues in the human body at arbitrary times during or after internal exposure to radioactive material. Presently there are few, if any, radionuclides for which sufficient metabolic information is available to allow full use of all features of the methodology. The intention has been to construct the methodology so that optimal information can be gained from a mixture of the limited amount of age-dependent, nuclide-specific data and the generally plentiful age-dependent physiological data now available. Moreover, an effort has been made to design the methodology so that constantly accumulating metabolic information can be incorporated with minimal alterations in the AGEDOS computer code. Some preliminary analyses performed by the authors, using the AGEDOS code in conjunction with age-dependent risk factors developed from the A-bomb survivor data and other studies, has indicated that the doses and subsequent risks of eventually experiencing radiogenic cancers may vary substantially with age for some exposure scenarios and may be relatively invariant with age for other scenarios. We believe that the AGEDOS methodology provides a convenient and efficient means for performing the internal dosimetry.

  12. Wh-Questions in Child L2 French: Derivational Complexity and Its Interactions with L1 Properties, Length of Exposure, Age of Exposure, and the Input

    ERIC Educational Resources Information Center

    Prévost, Philippe; Strik, Nelleke; Tuller, Laurie

    2014-01-01

    This study investigates how derivational complexity interacts with first language (L1) properties, second language (L2) input, age of first exposure to the target language, and length of exposure in child L2 acquisition. We compared elicited production of "wh"-questions in French in two groups of 15 participants each, one with L1 English…

  13. Mechanical properties of types 304 and 316 stainless steel after long-term aging and exposure

    SciTech Connect

    Horak, J.A.; Sikka, V.K.; Raske, D.T.

    1983-01-01

    Because designs for Liquid Metal Fast Breeder Reactor (LMFBR) power plants include plant lifetimes to 40 years, an understanding of the mechanical behavior of the structural alloys used is required for times of approx. 2 to 2.5 x 10/sup 5/ h. Most of the alloys used for LMFBR out-of-core structures and components are in a metastable state at the beginning of plant lifetime and evolve to a more stable state and, therefore, microstructure during plant operation. We reviewed mechanical properties and microstructures after prolonged elevated-temperature exposure of types 304 and 316 stainless steel, two alloys used extensively in fast breeder systems. Aging alters properties; in particular, it decreases toughness and tensile ductility, but the properties are still adequate for service. Because stable microstructures have been reached in long-term exposures achieved so far, properties can be expected to remain adequate for service life exposures.

  14. Evidence of subclinical prion disease in aged mice following exposure to bovine spongiform encephalopathy.

    PubMed

    Brown, Karen L; Mabbott, Neil A

    2014-01-01

    The occurrence of variant Creutzfeldt-Jakob (vCJD) disease in humans was almost certainly the result of consumption of food contaminated with bovine spongiform encephalopathy (BSE) prions. Despite probable widespread exposure of the UK population to BSE-contaminated food in the 1980s, vCJD has been identified predominantly in young individuals, and there have been fewer cases of clinical disease than anticipated. The reasons for this are uncertain. Following peripheral exposure, many prions replicate within the lymphoid tissues before infecting the central nervous system. We have shown that the effects of host age on the microarchitecture of the spleen significantly impair susceptibility to mouse-adapted prions after peripheral exposure. The transmission of prions between different mammalian species is considered to be limited by the 'species barrier', which is dependent on several factors, including an intact immune system. Thus, cross-species prion transmission may be much less efficient in aged individuals. To test this hypothesis, we compared prion pathogenesis in groups of young (6-8 weeks old) and aged (600 days old) mice injected with primary BSE brain homogenate. We showed that prion pathogenesis was impaired dramatically in aged mice when compared with young animals. Whereas most young mice succumbed to clinical prion disease, all aged mice failed to develop clinical disease during their lifespans. However, the demonstration that prion accumulation was detected in the lymphoid tissues of some aged mice after injection with primary BSE brain homogenate, in the absence of clinical signs of prion disease, has important implications for human health.

  15. Exposure to Famine at a Young Age and Unhealthy Lifestyle Behavior Later in Life

    PubMed Central

    Fransen, Heidi P.; Peeters, Petra H. M.; Beulens, Joline W. J.; Boer, Jolanda M. A.; de Wit, G. Ardine; Onland-Moret, N. Charlotte; van der Schouw, Yvonne T.; Bueno-de-Mesquita, H. Bas; Hoekstra, Jeljer; Elias, Sjoerd G.; May, Anne M.

    2016-01-01

    Background A healthy diet is important for normal growth and development. Exposure to undernutrition during important developmental periods such as childhood and adolescence can have effects later in life. Inhabitants of the west of the Netherlands were exposed to severe undernutrition during the famine in the last winter of the second World War (1944–1945). Objective We investigated if exposure of women to the Dutch famine during childhood and adolescence was associated with an unhealthy lifestyle later in life. Design We studied 7,525 women from the Prospect-EPIC cohort, recruited in 1993–97 and aged 0–18 years during the Dutch famine. An individual famine score was calculated based on self-reported information about experience of hunger and weight loss. We investigated the association between famine exposure in early life and four lifestyle factors in adulthood: smoking, alcohol consumption, physical activity level and a Mediterranean-style diet. Results Of the 7,525 included women, 46% were unexposed, 38% moderately exposed and 16% severely exposed to the Dutch famine. Moderately and severely exposed women were more often former or current smokers compared to women that did not suffer from the famine: adjusted prevalence ratio 1.10 (95% CI: 1.05; 1.14) and 1.18 (1.12; 1.25), respectively. They also smoked more pack years than unexposed women. Severely exposed women were more often physically inactive than unexposed women, adjusted prevalence ratio 1.32 (1.06; 1.64). Results did not differ between exposure age categories (0–9 and 10–17 years). We found no associations of famine exposure with alcohol consumption and no dose-dependent relations with diet. Conclusions Exposure to famine early in female life may be associated with higher prevalence of smoking and physical inactivity later in life, but not with unhealthy diet and alcohol consumption. PMID:27244088

  16. Exposure age and ice-sheet model constraints on Pliocene East Antarctic ice sheet dynamics.

    PubMed

    Yamane, Masako; Yokoyama, Yusuke; Abe-Ouchi, Ayako; Obrochta, Stephen; Saito, Fuyuki; Moriwaki, Kiichi; Matsuzaki, Hiroyuki

    2015-04-24

    The Late Pliocene epoch is a potential analogue for future climate in a warming world. Here we reconstruct Plio-Pleistocene East Antarctic Ice Sheet (EAIS) variability using cosmogenic nuclide exposure ages and model simulations to better understand ice sheet behaviour under such warm conditions. New and previously published exposure ages indicate interior-thickening during the Pliocene. An ice sheet model with mid-Pliocene boundary conditions also results in interior thickening and suggests that both the Wilkes Subglacial and Aurora Basins largely melted, offsetting increased ice volume. Considering contributions from West Antarctica and Greenland, this is consistent with the most recent IPCC AR5 estimate, which indicates that the Pliocene sea level likely did not exceed +20 m on Milankovitch timescales. The inception of colder climate since ∼3 Myr has increased the sea ice cover and inhibited active moisture transport to Antarctica, resulting in reduced ice sheet thickness, at least in coastal areas.

  17. Exposure ages and neutron capture record in lunar samples from Fra Mauro.

    NASA Technical Reports Server (NTRS)

    Lugmair, G. W.; Marti, K.

    1972-01-01

    Cosmic-ray exposure ages of Apollo 14 rocks and rock fragments obtained by the Kr81-Kr83 method range from 27 to 700 m.y. Rock 14321, collected near the Cone crater rim, is one of the many approximately 27 m.y. old ejecta which were reported at the Third Lunar Science Conference. All the other rocks have considerably higher exposure ages. Isotopic anomalies from neutron capture in gadolinium, bromine, and barium are used to obtain information on the lunar neutron spectrum at various depths below the lunar surface. The flux ratio of resonance and slow (less than 0.3 eV) neutrons is found to be nearly constant in the topmost approximately 100 g/sq cm.

  18. Exposure age and ice-sheet model constraints on Pliocene East Antarctic ice sheet dynamics

    PubMed Central

    Yamane, Masako; Yokoyama, Yusuke; Abe-Ouchi, Ayako; Obrochta, Stephen; Saito, Fuyuki; Moriwaki, Kiichi; Matsuzaki, Hiroyuki

    2015-01-01

    The Late Pliocene epoch is a potential analogue for future climate in a warming world. Here we reconstruct Plio-Pleistocene East Antarctic Ice Sheet (EAIS) variability using cosmogenic nuclide exposure ages and model simulations to better understand ice sheet behaviour under such warm conditions. New and previously published exposure ages indicate interior-thickening during the Pliocene. An ice sheet model with mid-Pliocene boundary conditions also results in interior thickening and suggests that both the Wilkes Subglacial and Aurora Basins largely melted, offsetting increased ice volume. Considering contributions from West Antarctica and Greenland, this is consistent with the most recent IPCC AR5 estimate, which indicates that the Pliocene sea level likely did not exceed +20 m on Milankovitch timescales. The inception of colder climate since ∼3 Myr has increased the sea ice cover and inhibited active moisture transport to Antarctica, resulting in reduced ice sheet thickness, at least in coastal areas. PMID:25908601

  19. Effects of prenatal marijuana exposure on child behavior problems at age 10.

    PubMed

    Goldschmidt, L; Day, N L; Richardson, G A

    2000-01-01

    This is a prospective study of the effects of prenatal marijuana exposure on child behavior problems at age 10. The sample consisted of low-income women attending a prenatal clinic. Half of the women were African-American and half were Caucasian. The majority of the women decreased their use of marijuana during pregnancy. The assessments of child behavior problems included the Child Behavior Checklist (CBCL), Teacher's Report Form (TRF), and the Swanson, Noland, and Pelham (SNAP) checklist. Multiple and logistic regressions were employed to analyze the relations between marijuana use and behavior problems of the children, while controlling for the effects of other extraneous variables. Prenatal marijuana use was significantly related to increased hyperactivity, impulsivity, and inattention symptoms as measured by the SNAP, increased delinquency as measured by the CBCL, and increased delinquency and externalizing problems as measured by the TRF. The pathway between prenatal marijuana exposure and delinquency was mediated by the effects of marijuana exposure on inattention symptoms. These findings indicate that prenatal marijuana exposure has an effect on child behavior problems at age 10.

  20. Surface exposure dating of Little Ice Age ice cap advances on Disko Island, West Greenland

    NASA Astrophysics Data System (ADS)

    Lane, Timothy; Jomelli, Vincent; Rinterknecht, Vincent; Brunstein, Daniel; Schimmelpfennig, Irene; Swingedouw, Didier; Favier, Vincent; Masson-Delmotte, Valerie

    2015-04-01

    Little Ice Age (LIA: 1200-1920 AD) glacier advances in Greenland often form the most extensive positions of Greenland Ice Sheet (GrIS) ice cap and margins since the Early Holocene. Across Greenland these advances are commonly represented by un-vegetated moraines, usually within 1-5 km of the present ice margin. However, chronological constraints on glacier advances during this period are sparse, meaning that GrIS and ice cap behavior and advance/retreat chronology remains poorly understood during this period. At present the majority of ages are based on historical accounts, ice core data, and radiocarbon ages from proglacial threshold lakes. However, developments in the accuracy and precision of surface exposure methods allow dating of LIA moraine boulders, permitting an opportunity to better understand of ice dynamics during this period. Geomorphological mapping and surface exposure dating (36Cl) were used to interpret moraine deposits from the Lyngmarksbræen on Disko Island, West Greenland. A Positive Degree Day (PDD) model was used to estimate Equilibrium Line Altitude (ELA) and mass balance changes for two distinct paleo-glacial extents. Three moraines (M1, M2, and M3) were mapped in the field, and sampled for 36Cl surface exposure dating. The outermost moraine (M1) was of clearly different morphology to the inner moraines, and present only in small fragments. M2 and M3 were distinct arcuate termino-lateral moraines within 50 m of one another, 1.5 km from the present ice margin. The weighted average of four 36Cl ages from M1 returned an early Holocene age of 8.4 ± 0.6 ka. M2 (four samples) returned an age of 0.57 ± 0.04 ka (1441 AD) and M3 (four samples) returned an age of 0.28 ± 0.02 ka (1732 AD). These surface exposure ages represent the first robustly dated Greenlandic ice cap moraine sequence from the LIA. The two periods of ice cap advance and marginal stabilisation are similar to recorded periods of LIA GrIS advance in west Greenland, constrained

  1. Gas-retention and cosmic-ray exposure ages of lunar rock 15555.

    PubMed

    Podosek, F A; Huneke, J C; Wasserburg, G J

    1972-01-28

    The last lava flow in the Hadley Rille area of Mare Imbrium, as inferred from an argon-40-argon-39 experiment on a plagioclase separate from the lunar basalt 15555, occurred 3.31+/-0.03x10(9) years ago. An argon-40-argon-39 experiment on a whole rock sample shows significant loss of radiogenic argon-40 and yields a well-defined, high-temperature plateau indicating a lower age of 3.22+/-0.03x10(9) years. A cosmic-ray exposure age of 90+/-10x10(6) years is determined from the ratio of spallogenic argon-38 to calcium.

  2. Exposure to mercury among Spanish preschool children: trend from birth to age four.

    PubMed

    Llop, Sabrina; Murcia, Mario; Aguinagalde, Xabier; Vioque, Jesus; Rebagliato, Marisa; Cases, Amparo; Iñiguez, Carmen; Lopez-Espinosa, Maria-Jose; Amurrio, Ascensión; Navarrete-Muñoz, Eva María; Ballester, Ferran

    2014-07-01

    The purpose of this study is to describe the total hair mercury concentrations and their determinants in preschool Spanish children, as well as to explore the trend in mercury exposure from birth to the age four. This evolution has been scarcely studied in other birth cohort studies. The study population was 580 four year old children participating in the INMA (i.e. Childhood and Environment) birth cohort study in Valencia (2008-2009). Total mercury concentration at age four was measured in hair samples by atomic absorption spectrometry. Fish consumption and other covariates were obtained by questionnaire. Multivariate linear regression models were conducted in order to explore the association between mercury exposure and fish consumption, socio-demographic characteristics and prenatal exposure to mercury. The geometric mean was 1.10 µg/g (95%CI: 1.02, 1.19). Nineteen percent of children had mercury concentrations above the equivalent to the Provisional Tolerable Weekly Intake proposed by WHO. Mercury concentration was associated with increasing maternal age, fish consumption and cord blood mercury levels, as well as decreasing parity. Children whose mothers worked had higher mercury levels than those with non working mothers. Swordfish, lean fish and canned fish were the fish categories most associated with hair mercury concentrations. We observed a decreasing trend in mercury concentrations between birth and age four. In conclusion, the children participating in this study had high hair mercury concentrations compared to reported studies on children from other European countries and similar to other countries with high fish consumption. The INMA study design allows the evaluation of the exposure to mercury longitudinally and enables this information to be used for biomonitoring purposes and dietary recommendations.

  3. Effects of exposure to heavy particles and aging on object recognition memory in rats

    NASA Astrophysics Data System (ADS)

    Rabin, Bernard; Joseph, James; Shukitt-Hale, Barbara; Carrihill-Knoll, Kirsty; Shannahan, Ryan; Hering, Kathleen

    Exposure to HZE particles produces changes in neurocognitive performance. These changes, including deficits in spatial learning and memory, object recognition memory and operant responding, are also observed in the aged organism. As such, it has been proposed that exposure to heavy particles produces "accelerated aging". Because aging is an ongoing process, it is possible that there would be an interaction between the effects of exposure and the effects of aging, such that doses of HZE particles that do not affect the performance of younger organisms will affect the performance of organisms as they age. The present experiments were designed to test the hypothesis that young rats that had been exposed to HZE particles would show a progressive deterioration in object recognition memory as a function of the age of testing. Rats were exposed to 12 C, 28 S or 48 Ti particles at the N.A.S.A. Space Radiation Laboratory at Brookhaven National Laboratory. Following irradiation the rats were shipped to UMBC for behavioral testing. HZE particle-induced changes in object recognition memory were tested using a standard procedure: rats were placed in an open field and allowed to interact with two identical objects for up to 30 sec; twenty-four hrs later the rats were again placed in the open field, this time containing one familiar and one novel object. Non-irradiated control animals spent significantly more time with the novel object than with the familiar object. In contrast, the rats that been exposed to heavy particles spent equal amounts of time with both the novel and familiar object. The lowest dose of HZE particles which produced a disruption of object recognition memory was determined three months and eleven months following exposure. The threshold dose needed to disrupt object recognition memory three months following irradiation varied as a function of the specific particle and energy. When tested eleven months following irradiation, doses of HZE particles that did

  4. On the calculation of cosmic-ray exposure ages of stone meteorites

    NASA Technical Reports Server (NTRS)

    Cressy, P. J., Jr.; Bogard, D. D.

    1976-01-01

    Abundances of cosmic ray-produced noble gases and Al-26, including some new measurements, have been compiled for some 23 stone meteorites with exposure ages less than 3,000,000 yr. Concentrations of cosmogenic He, Ne, and Ar in these meteorites have been corrected for differences in target element abundances by normalization to L-chondrite chemistry. Combined noble gas measurements in depth samples of the Keyes and St. Severin chondrites are utilized to derive equations for normalizing the production rates of cosmogenic He-3, Ne-21, and Ar-38 in chondrites to an adopted 'average' shielding. The measured unsaturated AL-26 concentrations and the calculated equilibrium Al-26 for these meteorites are combined to estimate exposure ages. These exposure ages are statistically compared with chemistry- and shielding-corrected concentrations of cosmogenic He, Ne, and Ar to derive absolute production rates for these nuclides, which are found to be roughly 25% higher than production rates used in the past. From these production rates and relative chemical correction factors, production rates for other classes of stone meteorites are derived.

  5. Cosmic-ray exposure ages of the ordinary chondrites and their significance for parent body stratigraphy

    NASA Technical Reports Server (NTRS)

    Crabb, J.; Schultz, L.

    1981-01-01

    Improved exposure ages are derived for 201 H, 203 L, and 38 LL chondrites in an effort to understand the characteristics of the chondrite parent body. The Ne-21 exposure ages were calculated from literature values taking into account shielding differences, a trapped component and radiogenic He. The exposure age distributions show clear peaks at 4.5 and 20 million years for the H chondrites, while the Ls and LLs appear more as a continuous series of intermediate peaks which may be modeled by at least six peaks between 1 and 35 million years in the case of L chondrites. The observations that every petrological type occurs in each large peak and contain solar wind gases suggest that the parent bodies have been fragmented and reassembled into a megabreccia. The H meteorites are proposed to represent the surface layer of a body with a substantial, active regolith as indicated by the relatively high abundances of solar gases. The L chondrites, on the other hand, are attributed to a parent body that was fragmented by collision about 500 million years ago.

  6. Interpersonal Trauma Exposure and Cognitive Development in Children to Age 8 Years: A Longitudinal Study

    PubMed Central

    Enlow, Michelle Bosquet; Egeland, Byron; Blood, Emily; Wright, Robert O.; Wright, Rosalind J.

    2013-01-01

    Background Childhood trauma exposure has been associated with deficits in cognitive functioning. The influence of timing of exposure on the magnitude and persistence of deficits is not well understood. The impact of exposure in early development has been especially under-investigated. This study examined the impact of interpersonal trauma exposure (IPT) in the first years of life on childhood cognitive functioning. Methods Children (N = 206) participating in a longitudinal birth cohort study were assessed prospectively for exposure to IPT (physical or emotional abuse or neglect, sexual abuse, witnessing maternal partner violence) between birth and 64 months. Child intelligent quotient scores (IQ) were assessed at 24, 64, and 96 months of age. Race/ethnicity, gender, socioeconomic status, maternal IQ, birth complications, birthweight, and cognitive stimulation in the home were also assessed. Results IPT was significantly associated with decreased cognitive scores at all time points, even after controlling for sociodemographic factors, maternal IQ, birth complications, birthweight, and cognitive stimulation in the home. IPT in the first two years appeared to be especially detrimental. On average, compared to children not exposed to IPT in the first two years, exposed children scored one-half standard deviation lower across cognitive assessments. Conclusion IPT in early life may have adverse effects on cognitive development. IPT during the first two years may have particular impact, with effects persisting at least into later childhood. PMID:22493459

  7. Arsenic Exposure and Immunotoxicity: a Review Including the Possible Influence of Age and Sex.

    PubMed

    Ferrario, Daniele; Gribaldo, Laura; Hartung, Thomas

    2016-03-01

    Increasing evidence suggests that inorganic arsenic, a major environmental pollutant, exerts immunosuppressive effects in epidemiological, in vitro, and animal models. The mechanisms, however, remain unclear, and little is known about variation in susceptibilities due to age and sex. We performed a review of the experimental and epidemiologic evidence on the association of arsenic exposure and immune diseases. The majority of the studies described arsenic as a potent immunosuppressive compound, though others have reported an increase in allergy and autoimmune diseases, suggesting that arsenic may also act as an immune system stimulator, depending on the dose or timing of exposure. Limited information, due to either the high concentrations of arsenic used in in vitro studies or the use of non-human data for predicting human risks, is available from experimental studies. Moreover, although there is emerging evidence that health effects of arsenic manifest differently between men and women, we found limited information on sex differences on the immunotoxic effects of arsenic. In conclusion, preliminary data show that chronic early-life exposure to arsenic might impair immune responses, potentially leading to increased risk of infections and inflammatory-like diseases during childhood and in adulthood. Further investigation to evaluate effects of arsenic exposure on the developing immune system of both sexes, particularly in human cells and using concentrations relevant to human exposure, should be a research priority.

  8. [sup 14]C and [sup 10]Be evidence for no incursion of the Lake Michigan lobe in northern Illinois from ca. 170 to 25 ka

    SciTech Connect

    Curry, B.B. ); Pavich, M.J. )

    1994-04-01

    Uncorrected [sup 10]Be inventories of a 2.7 m-long section of core indicate surface exposure lasting 115 ka during development of the Sangamon Geosol and 30 ka for a soil complex developed in overlying loessial sediment (Robein Silt). The latter estimate is in agreement with [sup 14]C assays in the region. Taking into account the age of overlying late Wisconsin drift, the new data indicate an age of about 170 ka for the onset of Sangamon pedogenesis in northern Illinois. Previous to this study, there have been no numerical-age determinations for the start of the last interglacial in northern IL. The data confirm a previous hypothesis that the Lake Michigan Lobe did not invade IL contemporaneous with deposition of Roxana Silt, or during the other period of midcontinental loess deposition suggest by TL ages of ca. 70 to 85 ka. The core was collected immediately south of the IL-WI border (42[degree] 30 minutes N, 88[degree] 30 minutes W) near Hebron, IL. Buried by 14 m of late Wisconsin drift, and the interval assayed for [sup 10]Be included 2.0 m of pedogenically-altered Illinoian sand and gravel, and 0.7 m of Wisconsin silt. One AMS [sup 14]C assay of carbonized fragments from the A-horizon of the Sangamon Geosol yielded an age of 38,500 [+-] 5,000 yr B.P.; conventional [sup 14]C ages for the overlying silt are from wood fragments (24,780 [times] 360 yr B.P.) and a bulk soil sample (26,030 [+-] 450 yr B.P.). The range of ages is typical for this stratigraphic sequence in IL. The [sup 10]Be concentration in the lowest part of the silt is 600 atoms/gm. This value is three times greater than the concentration typical of calcareous Mississippi River valley loess and of the C-horizon of the Sangamon Geosol in the core. High concentration of [sup 10]Be in the Robein Silt likely was caused by redeposition of [sup 10]Be-rich B-horizon material eroded from soil profiles elsewhere in the paleobasin.

  9. Loess 10Be evidence for an asynchronous Brunhes-Matuyama magnetic polarity reversal

    NASA Astrophysics Data System (ADS)

    Zhou, W.; Beck, W.; Kong, X.; An, Z.; Qiang, X.; Wu, Z.; Xian, F.; Ao, H.

    2015-12-01

    In Chinese loess the Brunhes-Matuyama (B-M) geomagnetic reversal appears to occur about 25 ka prior to the established axial dipole reversal age found in many marine sediments, i.e., in Chinese loess this magnetic reversal boundary is found in glacial loess unit L8 which is thought to be correlated with Marine Isotope Stage 20 (MIS 20), in marine sediment records, however, this boundary is commonly found in interglacial period of MIS 19[1-2], leading to the debate on uncertainties of paleoclimatic correlation between the Chinese loess-paleosol sequences and marine sediments[3-5]. Based on this issue, here we propose to use the cosmogenic 10Be to address this conundrum. 10Be is a long-lived radionuclide produced in the atmosphere by cosmic ray spallation reactions and carried to the ground attached to aerosols. Its atmospheric production rate is inversely proportional to the geomagnetic field intensity [6]. This allows us to reconstruct past geomagnetic field intensity variations using 10Be concentrations recorded in different sedimentary archives. We carried out both the 10Be studies and paleogeomagnetic measurements in Luochuan and Xifeng sections in Chinese Loess Plateau. Both loess profiles show that 10Be production rate was at a maximum-an indication of the dipole field reversal-at ca. 780 ± 3 ka BP., in paleosol unit S7 corresponding to MIS 19, proving that the timing of B-M reversal recorded in Chinese loess is synchronous with that seen in marine records [1]. These results reaffirmed the conventional paleoclimatic correlation of loess-paleosol sequences with marine isotope stages and the standard loess timescale as correct. However, it is ~25 ka younger than the age (depth) of the paleogeomagnetic measurements, which show that the B-M boundary is in L8 in these two Chinese loess-paleosol sequences, demonstrating that loess magnetic overprinting has occurred. 1.Tauxe, L., et al., 1996, EARTH PLANET SC LETT, 140, 133-1462.Zhou, L.P., and Shackleton, 1999

  10. Cosmogenic 10Be Chronologies of Moraines and Glacially Scoured Bedrock in the Teton Range, with Implications for Paleoclimatic Events and Tectonic Activity

    NASA Astrophysics Data System (ADS)

    Licciardi, J. M.; Pierce, K. L.; Thackray, G. D.; Finkel, R. C.; Zimmerman, S. R. H.

    2015-12-01

    At its Pleistocene maximum, the greater Yellowstone glacial system consisted of an ice cap on the Yellowstone Plateau joined by glaciers from adjacent high mountains, including the Teton Range. In prior research, we obtained 112 exposure ages from moraines and bedrock in this region. These chronologies identified asynchronous outlet glacier culminations around the periphery of the Yellowstone glacier complex, supporting a model of spatial and temporal progressions in buildup and decay of the various ice source regions. Here we build on this previous work and present >30 recently developed 10Be exposure ages on glacial features in the Teton Range. Although the Tetons harbored a relatively small portion of the greater Yellowstone ice complex, glaciers in this range left behind some of the region's best-preserved moraine sequences and scoured bedrock. Ongoing investigations are focused on developing moraine chronologies in several drainages on the eastern and western Teton Range fronts, and obtaining exposure ages along scoured bedrock transects in glacial troughs upvalley from the dated moraines to define rates of ice recession. Notably, our dating campaign includes lateral moraines that are offset by the Teton fault, providing a rare opportunity to establish direct constraints on integrated long-term slip rates. All new and previously obtained 10Be ages are calculated using recently published calibrations and scaling of 10Be production rates. Initial results show that massive lateral moraines in selected drainages are several thousands of years older than adjacent distal end moraines, implying that the laterals were constructed during an earlier phase of the last glaciation and then acted to topographically confine subsequent ice advances. Mean ages of ca. 17-16 ka from terminal moraine loops along with limiting ages from scoured bedrock upvalley of the moraines indicate glacier culminations followed by the onset of rapid ice retreat long after the end of the global

  11. U-Th and 10Be constraints on sediment recycling in proglacial settings, Lago Buenos Aires, Patagonia

    NASA Astrophysics Data System (ADS)

    Cogez, Antoine; Herman, Frédéric; Pelt, Eric; Norton, Kevin; Darvill, Christopher; Christl, Marcus; Morvan, Gilles; Reuschlé, Thierry; Chabaux, François

    2016-04-01

    The sedimentary cycle includes the formation by erosion of rocks, transport and deposition. While erosion and deposition can be documented, the history of sediments between the time it is extracted from the rocks and ultimately deposited into basins remains a major challenge. However, the mechanism of transfer and alteration of the sediments during transport plays a key role in the evolution of basins, feedbacks between erosion and climate, and glacial-interglacial variability of sediment transport and weathering. This is particularly true in proglacial settings because large overdeepenings, in particular, are potential sediment traps for which the efficiency at evacuating those sediments is largely unknown. The Lago Buenos Aires moraines in Patagonia are particularly interesting because they are imbricated from the older in the outer part to the younger in the inner part of the system. We sampled fine grained sediments from these moraines and measured U-Th isotopes in the 4-50 μm silicate fraction. Deposition ages were refined using 10Be exposure ages. We show first that the comminution ages model can be improved by measuring also Th isotopes, from which weathering rates can be deduced. Moreover we show from our data that there is a time lag of 300 kyr on average between erosion and deposition in the moraine. This could be attributed to the long residence time of sediments in the lake overdeepening. This conclusion raises perspectives about the transport times and dynamic of the sediments during a whole sedimentary cycle, and the subsequent effect on weathering. This conclusion could also contradict some assumptions commonly made for our erosion rates/sediment fluxes reconstructions based on river sediments analysis, in recently deglaciated catchments.

  12. Acetaminophen hepatotoxicity in mice: Effect of age, frailty and exposure type.

    PubMed

    Kane, Alice E; Mitchell, Sarah J; Mach, John; Huizer-Pajkos, Aniko; McKenzie, Catriona; Jones, Brett; Cogger, Victoria; Le Couteur, David G; de Cabo, Rafael; Hilmer, Sarah N

    2016-01-01

    Acetaminophen is a commonly used analgesic that can cause severe hepatotoxicity in overdose. Despite old age and frailty being associated with extensive and long-term utilization of acetaminophen and a high prevalence of adverse drug reactions, there is limited information on the risks of toxicity from acetaminophen in old age and frailty. This study aimed to assess changes in the risk and mechanisms of hepatotoxicity from acute, chronic and sub-acute acetaminophen exposure with old age and frailty in mice. Young and old male C57BL/6 mice were exposed to either acute (300 mg/kg via oral gavage), chronic (100 mg/kg/day in diet for six weeks) or sub-acute (250 mg/kg, t.i.d., for three days) acetaminophen, or saline control. Pre-dosing mice were scored for the mouse clinical frailty index, and after dosing serum and liver tissue were collected for assessment of toxicity and mechanisms. There were no differences with old age or frailty in the degree of hepatotoxicity induced by acute, chronic or subacute acetaminophen exposure as assessed by serum liver enzymes and histology. Age-related changes in the acetaminophen toxicity pathways included increased liver GSH concentrations, increased NQO1 activity and an increased pro- and anti-inflammatory response to acetaminophen in old age. Frailty-related changes included a negative correlation between frailty index and serum protein, albumin and ALP concentrations for some mouse groups. In conclusion, although there were changes in some pathways that would be expected to influence susceptibility to acetaminophen toxicity, there was no overall increase in acetaminophen hepatotoxicity with old age or frailty in mice.

  13. Calibration of cosmogenic 3He and 10Be production rates in the High Tropics

    NASA Astrophysics Data System (ADS)

    Blard, Pierre-Henri; Martin, Léo; Lavé, Jérôme; Charreau, Julien; Condom, Thomas; Lupker, Maarten; Braucher, Régis; Bourlès, Didier

    2014-05-01

    It is critical to refine both the accuracy and the precision of the in situ cosmogenic dating tool, especially for establishing reliable glacial chronologies that can be compared to other paleoclimatic records. Recent cross-calibrations of cosmogenic 3He in pyroxene and 10Be in quartz [1, 2] showed that, both at low (1300 m) and high elevation (4850 m), the 3He/10Be production ratio was probably ~40% higher than the value of ~23 initially defined in the 90's. This recent update is consistent with the last independent determinations of the sea level high latitude production rates of 10Be and 3He, that are about 4 and 125 at.g-1.yr-1, respectively [e.g. 3, 4]. However, major questions remain about these production rates at high elevation, notably because existing calibration sites for both 3He and 10Be are scarce above 2000 m. It is thus crucial to produce new high precision calibration data at high elevation. Here we report cosmogenic 10Be data from boulders sampled on a glacial fan located at 3800 m in the Central Altiplano (Bolivia), whose age is independently constrained by stratigraphic correlations and radiocarbon dating at ca. 16 ka. These data can be used to calibrate the production rate of 10Be at high elevation, in the Tropics. After scaling to sea level and high latitude, these data yield a sea level high latitude P10 ranging from 3.8 to 4.2 at.g-1.yr-1, depending on the used scaling scheme. These new calibration data are in good agreement with recent absolute and cross-calibration of 3He in pyroxenes and 10Be in quartz, from dacitic moraines located at 4850 m in the Southern Altiplano (22° S, Tropical Andes) [2,5]. The so-obtained 3He/10Be production ratio of 33.3±0.9 (1σ) combined with an absolute 3He production rate locally calibrated in the Central Altiplano, at 3800 m, indeed yielded a sea level high latitude P10 ranging from 3.7±0.2 to 4.1±0.2 at.g-1.yr-1, depending on the scaling scheme [2,5]. These values are also consistent with the 10Be

  14. Exposure to light at night accelerates aging and spontaneous uterine carcinogenesis in female 129/Sv mice

    PubMed Central

    Popovich, Irina G.; Zabezhinski, Mark A.; Panchenko, Andrei V.; Piskunova, Tatiana S.; Semenchenko, Anna V.; Tyndyk, Maragriata L.; Yurova, Maria N.; Anisimov, Vladimir N.

    2013-01-01

    The effect of the constant illumination on the development of spontaneous tumors in female 129/Sv mice was investigated. Forty-six female 129/Sv mice starting from the age of 2 mo were kept under standard light/dark regimen [12 h light (70 lx):12hr dark; LD, control group], and 46 of 129/Sv mice were kept under constant illumination (24 h a day, 2,500 lx, LL) from the age of 5 mo until to natural death. The exposure to the LL regimen significantly accelerated body weight gain, increased body temperature as well as acceleration of age-related disturbances in estrous function, followed by significant acceleration of the development of the spontaneous uterine tumors in female 129/Sv mice. Total tumor incidence as well as a total number of total or malignant tumors was similar in LL and LD group (p > 0.05). The mice from the LL groups survived less than those from the LD group (χ2 = 8.5; p = 0.00351, log-rank test). According to the estimated parameters of the Cox’s regression model, constant light regimen increased the relative risk of death in female mice compared with the control (LD) group (p = 0.0041). The data demonstrate in the first time that the exposure to constant illumination was followed by the acceleration of aging and spontaneous uterine tumorigenesis in female 129/Sv mice. PMID:23656779

  15. Cosmogenic 3He exposure ages of Pleistocene debris flows and desert pavements in Capitol Reef National Park, Utah

    NASA Astrophysics Data System (ADS)

    Marchetti, David W.; Cerling, Thure E.

    2005-04-01

    The Quaternary history of the Capitol Reef area, Utah, is closely linked to the basaltic-andesite boulder deposits that cover much of the landscape. Understanding the age and mode of emplacement of these deposits is crucial to deciphering the Quaternary evolution of this part of the Colorado Plateau. Using cosmogenic 3He exposure age dating, we obtained apparent exposure ages for several key deposits in the Capitol Reef area. Coarse boulder diamicts capping the Johnson Mesa and Carcass Creek Terraces are not associated with the Bull Lake glaciation as previously thought, but were deposited 180±15 to 205±17 ka (minimum age) and are the result of debris flow deposition. Desert pavements on the Johnson Mesa surface give exposure ranging from 97±8 to 159±14 ka and are 34-96 kyears younger than the boulder exposure ages. The offset between the boulder and pavement exposure ages appears to be related to a delay in pavement formation until the penultimate glacial/interglacial transition or periodic burial and exposure of pavement clasts since debris flow deposition. Incision rates for the Capitol Reef reach of the Fremont River calculated from the boulder exposure ages range from 0.40 to 0.43 m kyear -1 (maximum rates) and are some of the highest on the Colorado Plateau.

  16. Testing seismic hazard models with Be-10 exposure ages for precariously balanced rocks

    NASA Astrophysics Data System (ADS)

    Rood, D. H.; Anooshehpoor, R.; Balco, G.; Brune, J.; Brune, R.; Ludwig, L. Grant; Kendrick, K.; Purvance, M.; Saleeby, I.

    2012-04-01

    Currently, the only empirical tool available to test maximum earthquake ground motions spanning timescales of 10 ky-1 My is the use of fragile geologic features, including precariously balanced rocks (PBRs). The ages of PBRs together with their areal distribution and mechanical stability ("fragility") constrain probabilistic seismic hazard analysis (PSHA) over long timescales; pertinent applications include the USGS National Seismic Hazard Maps (NSHM) and tests for ground motion models (e.g., Cybershake). Until recently, age constraints for PBRs were limited to varnish microlamination (VML) dating techniques and sparse cosmogenic nuclide data; however, VML methods yield minimum limiting ages for individual rock surfaces, and the interpretations of cosmogenic nuclide data were ambiguous because they did not account for the exhumation history of the PBRs or the complex shielding of cosmic rays. We have recently published a robust method for the exposure dating of PBRs combining Be-10 profiles, a numerical model, and a three-dimensional model for each PBR constructed using photogrammetry (Balco et al., 2011, Quaternary Geochronology). Here, we use this method to calculate new exposure ages and fragilities for 6 PBRs in southern California (USA) near the San Andreas, San Jacinto, and Elsinore faults at the Lovejoy Buttes, Round Top, Pacifico, Beaumont South, Perris, and Benton Road sites (in addition to the recently published age of 18.7 +/- 2.8 ka for a PBR at the Grass Valley site). We combine our ages and fragilities for each PBR, and use these data to test the USGS 2008 NSHM PGA with 2% in 50 year probability, USGS 2008 PSHA deaggregations, and basic hazard curves from USGS 2002 NSHM data.

  17. Testing seismic hazard models with Be-10 exposure ages for precariously balanced rocks

    NASA Astrophysics Data System (ADS)

    Rood, D. H.; Anooshehpoor, R.; Balco, G.; Biasi, G. P.; Brune, J. N.; Brune, R.; Grant Ludwig, L.; Kendrick, K. J.; Purvance, M.; Saleeby, I.

    2012-12-01

    Currently, the only empirical tool available to test maximum earthquake ground motions spanning timescales of 10 ky-1 My is the use of fragile geologic features, including precariously balanced rocks (PBRs). The ages of PBRs together with their areal distribution and mechanical stability ("fragility") constrain probabilistic seismic hazard analysis (PSHA) over long timescales; pertinent applications include the USGS National Seismic Hazard Maps (NSHM) and tests for ground motion models (e.g., Cybershake). Until recently, age constraints for PBRs were limited to varnish microlamination (VML) dating techniques and sparse cosmogenic nuclide data; however, VML methods yield minimum limiting ages for individual rock surfaces, and the interpretations of cosmogenic nuclide data were ambiguous because they did not account for the exhumation history of the PBRs or the complex shielding of cosmic rays. We have recently published a robust method for the exposure dating of PBRs combining Be-10 profiles, a numerical model, and a three-dimensional shape model for each PBR constructed using photogrammetry (Balco et al., 2011, Quaternary Geochronology). Here, we use our published method to calculate new exposure ages for PBRs at 6 sites in southern California near the San Andreas, San Jacinto, and Elsinore faults, including: Lovejoy Buttes (9 +/- 1 ka), Round Top (35 +/- 1 ka), Pacifico (19 +/- 1 ka, but with a poor fit to data), Beaumont South (17 +/- 2 ka), Perris (24 +/- 2 ka), and Benton Road (40 +/- 1 ka), in addition to the recently published age of 18.5 +/- 2.0 ka for a PBR at the Grass Valley site. We combine our ages and fragilities for each PBR, and use these data to test the USGS 2008 NSHM PGA with 2% in 50 year probability, USGS 2008 PSHA deaggregations, and basic hazard curves from USGS 2002 NSHM data. Precariously balanced rock in southern California

  18. Perinatal air pollution exposure and development of asthma from birth to age 10 years.

    PubMed

    Sbihi, Hind; Tamburic, Lillian; Koehoorn, Mieke; Brauer, Michael

    2016-04-01

    Within-city variation in air pollution has been associated with childhood asthma development, but findings have been inconsistent. We examined whether perinatal air pollution exposure affected asthma onset during "pre-school and "school age" periods in a population-based birth cohort.65,254 children born between 1999 and 2002 in the greater Vancouver metropolitan region were followed until age 10 years using linked administrative health databases. Asthma cases were sex- and age-matched to five randomly chosen controls. Associations between exposure to air pollutants estimated with different methods (interpolation (inverse-distance weighted (IDW)), land use regression, proximity) and incident asthma during the pre-school (0-5 years) and school age (6-10 years) periods were estimated with conditional logistic regression.6948 and 1711 cases were identified during the pre-school and school age periods, respectively. Following adjustment for birthweight, gestational period, household income, parity, breastfeeding at discharge, maternal age and education, asthma risk during the pre-school years was increased by traffic pollution (adjusted odds ratio using IDW method per interquartile increase (95% CI): nitric oxide 1.06 (1.01-1.11), nitrogen dioxide 1.09 (1.04-1.13) and carbon monoxide 1.05 (1.01-1.1)). Enhanced impacts were observed amongst low-term-birthweight cases. Associations were independent of surrounding residential greenness.Within-city air pollution variation was associated with new asthma onset during the pre-school years.

  19. 10Be Content in Suevite Breccia from the Bosumtwi Impact Crater

    NASA Astrophysics Data System (ADS)

    Losiak, Anna; Wild, Eva Maria; Michlmayr, Leonard; Koeberl, Christian

    2013-04-01

    Introduction: According to the current understanding of meteorite impact processes, surface target material is transported from a crater in the form of ejecta or is vaporized/melted (e.g., [1]). The formation model of tektites from the surface of the target rocks has been established using the 10Be content of tektites (e.g., [2]), and chemical comparison with the possible target surface material (e.g., [3]); it was also reproduced by computer modeling (e.g., [4]). On the other hand, some observations ([5, 6]) suggest that part of the surface material may be incorporated into the crater-fill. The aim of this study is to check if surface-derived material is present in suevitic breccias to better understand formation mechanisms of fallback breccias. Also, 10Be can be used to trace contamination of rocks in the top layer of the suevitic layer by meteoric (lake) water. This abstract is an update (based on more data now available) of the previous report presented during the Metsoc75 conference. Samples: The Bosumtwi crater was chosen as study site because of its relatively large size (10.5 km in diameter), young age of 1.07 Ma [7], good state of preservation, and availability of core samples. Clasts from suevitic breccia selected for this study come from the LB-07A and LB-08A cores that are located within the crater and represent fallback breccia (e.g., [7]). Of 41 analyzed samples (22 single clasts and 21 matrix samples - 11 of those being monomictic breccia), 36 came from core LB-07A (in the zone outside the central uplift) and represent depths of 333.7 - 407.9 m and 5 are from core LB-08A (on the flank of the central uplift) from depths 239.5 - 264.9 m. Methods: For each sample, 0.8 g of finely grounded material from clasts containing in situ produced and meteoric 10Be was dissolved in a mixture of HF and HNO3 by microwave digestion. A 9Be carrier (1 mg or 0.6 mg, 10Be/9Be ratio: 2.82±0.31*10-15 [2? uncertainty]) was added to the sample, and then Be was chemically

  20. Deoxynivalenol Exposure in Norway, Risk Assessments for Different Human Age Groups

    PubMed Central

    Sundheim, Leif; Lillegaard, Inger Therese; Fæste, Christiane Kruse; Brantsæter, Anne-Lise; Brodal, Guro; Eriksen, Gunnar Sundstøl

    2017-01-01

    Deoxynivalenol (DON) is the most common mycotoxin in Norwegian cereals, and DON is detected in most samples of crude cereal grain and cereal food commodities such as flour, bran, and oat flakes. The Norwegian Scientific Committee for Food Safety assessed the risk for adverse effects of deoxynivalenol (DON) in different age groups of the domestic population. This review presents the main results from the risk assessment, supplemented with some recently published data. Impairment of the immune system together with reduced feed intake and weight gain are the critical effects of DON in experimental animals on which the current tolerable daily intake was established. Based on food consumption and occurrence data, the mean exposure to DON in years with low and high levels of DON in the flour, respectively, were in the range of or up to two times the Tolerable Daily Intake (TDI) in 1-year-old infants and 2-year-old children. In years with high mean DON concentration, the high (95th-percentile) exposure exceeded the TDI by up to 3.5 times in 1-, 2- , 4-, and 9-year-old children. The assessment concluded that exceeding the TDI in infants and children is of concern. The estimated dietary DON intakes in adolescent and adult populations are in the range of the TDI or below, and are not a health concern. Acute human exposure to DON is not of concern in any age group. PMID:28165414

  1. Maternal Exposure to Pyrethroid Insecticides during Pregnancy and Infant Development at 18 Months of Age.

    PubMed

    Hisada, Aya; Yoshinaga, Jun; Zhang, Jie; Kato, Takahiko; Shiraishi, Hiroaki; Shimodaira, Kazuhisa; Okai, Takashi; Ariki, Nagako; Komine, Yoko; Shirakawa, Miyako; Noda, Yumiko; Kato, Nobumasa

    2017-01-08

    The possible association between maternal exposure to pyrethroid insecticides (PYRs) during pregnancy and infant development was explored. Levels of exposure to PYRs was assessed by metabolite (3-phenoybenzoic acid, 3-PBA) concentration in maternal spot urine sampled in the first trimester of index pregnancy, and infant development was assessed at 18 months of age using the Kinder Infants Development Scale (KIDS), which is based on a questionnaire to the caretaker. The relationship between KIDS score and maternal urinary 3-PBA levels was examined by a stepwise multiple regression analysis using biological attributes of the mother and infant, breast feeding, and nursing environment as covariates. The analysis extracted 3-PBA and the nursing environment as significant to explain the KIDS score at 18 months of age with positive partial regression coefficients. Inclusion of fish consumption frequency of the mother during pregnancy as an independent variable resulted in the selection of fish consumption as significant, while the two variables were marginally insignificant but still with a positive coefficient with the KIDS score. The result suggested a positive effect of maternal PYR exposure on infant development, the reason for which is not clear, but an unknown confounding factor is suspected.

  2. Graphical method for forecasting radiation exposure from multi-aged fallout from nuclear weapons

    SciTech Connect

    Haaland, C.M.

    1986-06-01

    After a nuclear attack it may be necessary for emergency workers, such as firemen, utility workers and medical personnel, to perform urgent tasks in areas highly contaminated by radioactive fallout. To assist the control of radiation exposure of these workers, it will be useful to provide means to forecast radiation exposures both inside and outside the fallout shelter. The method described in this paper is intended for use during the first few days to weeks after the attack, after which time more sophisticated methods may become available. This method requires only a radiation-rate meter, special graph paper, and a timepiece. Communications with Emergency Operating Centers or other sources of information are not necessary. The method permits the determination of the age of fallout and future exposure rates for a location that might be subjected to a number of different fallout clouds, without requiring knowledge of the weapon yields or times of detonation. This method will provide results with less accuracy if different-aged fallout clouds arrive simultaneously. The method is self-correcting so that if the actual decay rate is different than that which is assumed, the forecasted rates will have less error than results obtained by previous methods.

  3. A graphical method for forecasting radiation exposure from multi-aged fallout from nuclear weapons.

    PubMed

    Haaland, C M

    1986-06-01

    After a nuclear attack it may be necessary for emergency workers, such as firemen, utility workers and medical personnel, to perform urgent tasks in areas highly contaminated by radioactive fallout. To assist the control of radiation exposure of these workers, it will be useful to provide means to forecast radiation exposures both inside and outside the fallout shelter. The method described in this paper is intended for use during the first few days to weeks after the attack, after which time more sophisticated methods may become available. This method requires only a radiation-rate meter, special graph paper, and a timepiece. Communications with Emergency Operating Centers or other sources of information are not necessary. The method permits the determination of the age of fallout and future exposure rates for a location that might be subjected to a number of different fallout clouds, without requiring knowledge of the weapon yields or times of detonation. This method will provide results with less accuracy if different-aged fallout clouds arrive simultaneously. The method is self-correcting so that if the actual decay rate is different than that which is assumed, the forecasted rates will have less error than results obtained by previous methods.

  4. Maternal Exposure to Pyrethroid Insecticides during Pregnancy and Infant Development at 18 Months of Age

    PubMed Central

    Hisada, Aya; Yoshinaga, Jun; Zhang, Jie; Katoh, Takahiko; Shiraishi, Hiroaki; Shimodaira, Kazuhisa; Okai, Takashi; Ariki, Nagako; Komine, Yoko; Shirakawa, Miyako; Noda, Yumiko; Kato, Nobumasa

    2017-01-01

    The possible association between maternal exposure to pyrethroid insecticides (PYRs) during pregnancy and infant development was explored. Levels of exposure to PYRs was assessed by metabolite (3-phenoybenzoic acid, 3-PBA) concentration in maternal spot urine sampled in the first trimester of index pregnancy, and infant development was assessed at 18 months of age using the Kinder Infants Development Scale (KIDS), which is based on a questionnaire to the caretaker. The relationship between KIDS score and maternal urinary 3-PBA levels was examined by a stepwise multiple regression analysis using biological attributes of the mother and infant, breast feeding, and nursing environment as covariates. The analysis extracted 3-PBA and the nursing environment as significant to explain the KIDS score at 18 months of age with positive partial regression coefficients. Inclusion of fish consumption frequency of the mother during pregnancy as an independent variable resulted in the selection of fish consumption as significant, while the two variables were marginally insignificant but still with a positive coefficient with the KIDS score. The result suggested a positive effect of maternal PYR exposure on infant development, the reason for which is not clear, but an unknown confounding factor is suspected. PMID:28075338

  5. Brunhes-Matuyama Magnetic Polarity Reversal Tracing using Chinese loess10Be

    NASA Astrophysics Data System (ADS)

    Zhou, W.; Beck, W.; Kong, X.; An, Z.; Qiang, X.; Wu, Z.; Xian, F.; Ao, H.

    2014-12-01

    The geomagnetic polarity reversal is generally considered to occur synchronously around the world, and is commonly used as a time marker. However, in the case of the most recent reversal, the Brunhes-Matuyama (B-M) reversal (~780 ka), comparison of paleomagnetic studies in Chinese loess-paleosol sequences versus marine sediments revealed a marked discrepancy in timing of this event (Tauxe et al., 1996; Zhou and Shackleton, 1999), leading to the debate on uncertainties of paleoclimatic correlation between the Chinese loess-paleosol sequences and marine sediments (Wang et al., 2006; Liu et al., 2008; Jin and Liu, 2011). Based on this issue, here we propose to use the cosmogenic 10Be to address this conundrum. 10Be is a long-lived radionuclide produced in the atmosphere by cosmic ray spallation reactions and carried to the ground attached to aerosols. Its atmospheric production rate is inversely proportional to the geomagnetic field intensity (Masarik and Beer, 1999). This allows us to reconstruct past geomagnetic field intensity variations using 10Be concentrations recorded in different sedimentary archives. We carried out the 10Be studies in Luochuan and Xifeng sections in Chinese Loess Plateau, both loess profiles show that 10Be production rate was at a maximum-an indication of the dipole field reversal-at ca. 780 ± 3 ka BP., in paleosol unit S7corresponding to MIS 19. These results have proven that the timing of B-M reversal recorded in Chinese loess is synchronous with that seen in marine records (Tauxe et al., 1996) and reaffirmed the conventional paleoclimatic correlation of loess-paleosol sequences with marine isotope stages and the standard loess timescale as correct. However, it is ~25 ka younger than the age (depth) of the magnetic polarity reversal recorded in these same Chinese loess-paleosol sequences, demonstrating that loess magnetic overprinting has occurred. 1.Jin, C.S.,et al., 2011,PALAEOGEOGR PALAEOCL, 299, 309-3172.Liu, Q.S., et al., 2008, EARTH

  6. Assessing dietary exposure to cadmium in a metal recycling community in Vietnam: age and gender aspects.

    PubMed

    Ngo, Duc Minh; Hough, Rupert Lloyd; Le, Thi Thuy; Nyberg, Ylva; Le, Bach Mai; Nguyen, Cong Vinh; Nguyen, Manh Khai; Oborn, Ingrid

    2012-02-01

    This study estimates the dietary exposure to cadmium (Cd), and associated potential health risks, for individuals living and working in a metal recycling community (n=132) in Vietnam in comparison to an agricultural (reference) community (n=130). Individual-level exposure to Cd was estimated through analysis of staple foodstuffs combined with information from a food frequency questionnaire. Individual-level exposure estimates were compared with published 'safe' doses to derive a Hazard Quotient (HQ) for each member of the study population. Looking at the populations as a whole, there were no significant differences in the diets of the two villages. However, significantly more rice was consumed by working age adults (18-60 years) in the recycling village compared to the reference village (p<0.001). Rice was the main staple food with individuals consuming 461±162g/d, followed by water spinach (103±51kg/d). Concentrations of Cd in the studied foodstuffs were elevated in the metal recycling village. Values of HQ exceeded unity for 87% of adult participants of the metal recycling community (39% had a HQ>3), while 20% of adult participants from the reference village had an HQ>1. We found an elevated health risk from dietary exposure to Cd in the metal recycling village compared to the reference community. WHO standard of 0.4mg Cd/kg rice may not be protective where people consume large amounts of rice/have relatively low body weight.

  7. Associations of Prenatal Exposure to Organophosphate Pesticide Metabolites with Gestational Age and Birth Weight

    PubMed Central

    Rauch, Stephen A.; Braun, Joe M.; Barr, Dana Boyd; Calafat, Antonia M.; Khoury, Jane; Montesano, M. Angela; Yolton, Kimberly

    2012-01-01

    Background: Prenatal exposure to organophosphate (OP) insecticides, a widely used class of pesticides, may be associated with decreased gestational age and lower birth weight. Single nucleotide polymorphisms in paroxanase (PON1) enzyme genotypes may modify the relationships between OP exposure and perinatal outcomes. Objective: We examined the relationship of prenatal OP insecticide exposure, measured using urinary dialkyl phosphate (DAP) metabolite concentrations, with gestational age and birth weight. Methods: We measured the concentrations of six nonspecific DAP metabolites of OP insecticides in two maternal spot urine samples collected in a prospective birth cohort. We performed multivariable regression to examine associations between the sum of six DAP concentrations (ΣDAP) with gestational age and birth weight. We also examined whether these associations differed according to infant PON1192 and PON1–108 genotypes. Results: Among 306 mother–infant dyads, a 10-fold increase in ΣDAP concentrations was associated with a decrease in covariate-adjusted gestational age [–0.5 weeks; 95% confidence interval (CI): –0.8, –0.1] and birth weight (–151 g; CI: –287, –16); the decrements in birth weight were attenuated after adjusting for gestational age. The relationship between ΣDAP concentrations and gestational age was stronger for white (–0.7 weeks; CI: –1.1, –0.3) than for black (–0.1 weeks; 95% CI: –0.9, 0.6) newborns. In contrast, there was a greater decrease in birth weight with increasing urinary ΣDAP concentrations for black (–188 g; CI: –395, 19) than for white (–118 g; CI: –296, 60) newborns. Decrements in birth weight and gestational age associated with ΣDAP concentrations were greatest among infants with PON1192QR and PON–108CT genotypes. Conclusions: Prenatal urinary ΣDAP concentrations were associated with shortened gestation and reduced birth weight in this cohort, but the effects differed by race/ethnicity and PON

  8. Exposure to mercury among Spanish preschool children: Trend from birth to age four

    SciTech Connect

    Llop, Sabrina; Murcia, Mario; Aguinagalde, Xabier; Vioque, Jesus; Rebagliato, Marisa; Iñiguez, Carmen; Lopez-Espinosa, Maria-Jose; Amurrio, Ascensión; María Navarrete-Muñoz, Eva; and others

    2014-07-15

    The purpose of this study is to describe the total hair mercury concentrations and their determinants in preschool Spanish children, as well as to explore the trend in mercury exposure from birth to the age four. This evolution has been scarcely studied in other birth cohort studies. The study population was 580 four year old children participating in the INMA (i.e. Childhood and Environment) birth cohort study in Valencia (2008–2009). Total mercury concentration at age four was measured in hair samples by atomic absorption spectrometry. Fish consumption and other covariates were obtained by questionnaire. Multivariate linear regression models were conducted in order to explore the association between mercury exposure and fish consumption, socio-demographic characteristics and prenatal exposure to mercury. The geometric mean was 1.10 µg/g (95%CI: 1.02, 1.19). Nineteen percent of children had mercury concentrations above the equivalent to the Provisional Tolerable Weekly Intake proposed by WHO. Mercury concentration was associated with increasing maternal age, fish consumption and cord blood mercury levels, as well as decreasing parity. Children whose mothers worked had higher mercury levels than those with non working mothers. Swordfish, lean fish and canned fish were the fish categories most associated with hair mercury concentrations. We observed a decreasing trend in mercury concentrations between birth and age four. In conclusion, the children participating in this study had high hair mercury concentrations compared to reported studies on children from other European countries and similar to other countries with high fish consumption. The INMA study design allows the evaluation of the exposure to mercury longitudinally and enables this information to be used for biomonitoring purposes and dietary recommendations. - Highlights: • The geometric mean of hair Hg concentrations was 1.10 µg/g. • 19% of children had Hg concentrations above the RfD proposed by

  9. Cannabis exposure as an interactive cardiovascular risk factor and accelerant of organismal ageing: a longitudinal study

    PubMed Central

    Reece, Albert Stuart; Hulse, Gary Kenneth

    2016-01-01

    Objectives Many reports exist of the cardiovascular toxicity of smoked cannabis but none of arterial stiffness measures or vascular age (VA). In view of its diverse toxicology, the possibility that cannabis-exposed patients may be ageing more quickly requires investigation. Design Cross-sectional and longitudinal, observational. Prospective. Setting Single primary care addiction clinic in Brisbane, Australia. Participants 11 cannabis-only smokers, 504 tobacco-only smokers, 114 tobacco and cannabis smokers and 534 non-smokers. Exclusions: known cardiovascular disease or therapy or acute exposure to alcohol, amphetamine, heroin or methadone. Intervention Radial arterial pulse wave tonometry (AtCor, SphygmoCor, Sydney) performed opportunistically and sequentially on patients between 2006 and 2011. Main outcome measure Algorithmically calculated VA. Secondary outcomes: other central haemodynamic variables. Results Differences between group chronological ages (CA, 30.47±0.48 to 40.36±2.44, mean±SEM) were controlled with linear regression. Between-group sex differences were controlled by single-sex analysis. Mean cannabis exposure among patients was 37.67±7.16 g-years. In regression models controlling for CA, Body Mass Index (BMI), time and inhalant group, the effect of cannabis use on VA was significant in males (p=0.0156) and females (p=0.0084). The effect size in males was 11.84%. A dose–response relationship was demonstrated with lifetime exposure (p<0.002) additional to that of tobacco and opioids. In both sexes, the effect of cannabis was robust to adjustment and was unrelated to its acute effects. Significant power interactions between cannabis exposure and the square and cube of CA were demonstrated (from p<0.002). Conclusions Cannabis is an interactive cardiovascular risk factor (additional to tobacco and opioids), shows a prominent dose–response effect and is robust to adjustment. Cannabis use is associated with an acceleration of the cardiovascular

  10. Gender and age differences in mixed metal exposure and urinary excretion

    SciTech Connect

    Berglund, Marika; Lindberg, Anna-Lena; Rahman, Mahfuzar; Yunus, Mohammad; Grander, Margaretha; Loennerdal, Bo; Vahter, Marie

    2011-11-15

    Background: Little is known about the variation in exposure to toxic metals by age and gender and other potential modifying factors. We evaluated age and gender differences by measurements of metal/element concentrations in urine in a rural population in Matlab, Bangladesh, in three age groups: 8-12 (N=238), 14-15 (N=107) and 30-88 (N=710) years of age, living in an area with no point sources of metal exposure but where elevated water arsenic concentrations are prevalent. Results: We found marked differences in urine concentrations of metals and trace elements by gender, age, tobacco use, socioeconomic and nutritional status. Besides a clearly elevated urinary arsenic concentration in all age groups (medians 63-85 {mu}g As/L), and despite the low degree of contamination from industries and traffic, the urine concentrations of toxic metals such as cadmium and lead were clearly elevated, especially in children (median 0.31 {mu}g Cd/L and 2.9 {mu}g Pb/L, respectively). In general, women had higher urinary concentrations of toxic metals, especially Cd (median 0.81 {mu}g/L) compared to men (0.66 {mu}g/L) and U (median 10 ng/L in women, compared to 6.4 ng/L in men), while men had higher urinary concentrations of the basic and essential elements Ca (69 mg/L in men, 30-50 years, compared to 52 mg/L in women), Mg (58 mg/L in men compared to 50 mg/L in women), Zn (182 {mu}g/L in men compared to 117 {mu}g/L in women) and Se (9.9 {mu}g/L in men compared to 8.7 {mu}g/L in women). Manganese was consistently higher in females than in males in all age groups, suggesting a biological difference between females and males in Mn metabolism. Increasing socioeconomic status decreased the toxic metal exposure significantly in children and especially in men. Poor iron status was detected in 17% of children, adolescents and women, but only in 6% of men. Also zinc deficiency was more prevalent in females than in males. Conclusions: Women and children seemed to be more at risk for toxic

  11. Exposure to Chlamydia pneumoniae infection and progression of age-related macular degeneration.

    PubMed

    Robman, Luba; Mahdi, Olaimatu; McCarty, Catherine; Dimitrov, Peter; Tikellis, Gabriella; McNeil, John; Byrne, Gerald; Taylor, Hugh; Guymer, Robyn

    2005-06-01

    Recent studies have found an association between exposure to Chlamydia pneumoniae infection and risk of age-related macular degeneration (AMD). To assess a potential risk of AMD progression posed by exposure to C. pneumoniae, the authors reexamined Australian residents in 2001-2002 who were aged 51-89 years with early AMD at baseline (1992-1995). Examination included macular photography and an enzyme-linked immunosorbent assay to determine antibody titers to the elementary bodies from C. pneumoniae AR39. AMD progression was assessed quantitatively, using both coarse and fine progression steps following an international classification for AMD grading, and also qualitatively, by side-by-side comparison of baseline and follow-up macular photographs. Serologic data were available for 246 of 254 (97%) subjects. AMD progression was associated with a higher antibody titer. After adjustment for age, smoking, family history of AMD, history of cardiovascular diseases, and source study, the subjects in the upper tertiles of antibody titers were 2.1 (95% confidence interval: 0.92, 4.69), 2.6 (95% confidence interval: 1.24, 5.41), and 3.0 (95% confidence interval: 1.46, 6.37) times more at risk of progression than those in the lowest tertile, using three definitions of progression, respectively. The fact that seroreactivity to C. pneumoniae was independently associated with the risk of AMD progression suggests that C. pneumoniae infection may be an additional risk factor for AMD progression.

  12. Early Childhood Household Smoke Exposure Predicts Less Task-Oriented Classroom Behavior at Age 10.

    PubMed

    Pagani, Linda S; Fitzpatrick, Caroline

    2016-10-01

    Secondhand tobacco smoke is considered a developmental neurotoxicant especially given underdeveloped vital systems in young children. An ecological test of its negative influence on brain development can be made by examining the prospective association between early childhood household smoke exposure and later classroom behavior. Using a longitudinal birth cohort, we examined the unique contribution of household tobacco smoke exposure to children's subsequent classroom engagement at age 10. From child ages 1.5 to 7 years, parents of 2,055 participants from the Quebec Longitudinal Study of Child Development reported on household smoking by themselves and other home occupants. At age 10, fourth-grade teachers reported on the child's classroom engagement. In terms of prevalence, 58% of parents reported that their children were never exposed to smoke in the home, while 34% and 8% of children were exposed to transient and continuous household smoke, respectively. Compared with never exposed children, those who were exposed to transient and continuous household smoke scored 13% and 9% of a standard deviation lower on classroom engagement in fourth grade, standardized B = -.128 (95% confidence interval = -.186, -.069) and standardized B = -.093 (95% confidence interval = -.144, -.043), respectively. Compared with their never exposed peers, children exposed to transient and continuous early childhood household smoke showed proportionately less classroom engagement, which reflects task-orientation, following directions, and working well autonomously and with others. This predisposition poses risks for high school dropout, which from a population health perspective is closely linked with at-risk lifestyle habits and unhealthy outcomes.

  13. Ca-41 in iron falls, Grant and Estherville - Production rates and related exposure age calculations

    NASA Technical Reports Server (NTRS)

    Fink, D.; Klein, J.; Middleton, R.; Vogt, S.; Herzog, G. F.

    1991-01-01

    Results are presented of the first phase of a Ca-41 cosmogenic studies program aimed at establishing baseline concentrations and trends in selected meteorites and the use of Ca-41 in estimating exposure ages and preatmospheric meteorite radii. The average Ca-41 saturation activity recorded in four small iron falls is 24 +/-1 dpm/kg. This finding, together with measurements at the center and surface of the large iron Grant, indicates that production of Ca-41 from spallation on iron is weakly dependent on shielding to depths as large as 250 g/sq cm. The (K-41)-Ca-41 exposure age of Grant is estimated at 330 +/-50 My, and an upper limit to its terrestrial age of 43 +/-15 ky. A comparison of the Ca-41 contents of stony and metallic material separated from the mesosiderite Estherville identifies low-energy neutron capture on native Ca as a second important channel of production. It is found that the Ca-41 signal in the stone phase from three meteorites correlates with their size, and that the inferred low-energy neutron fluxes vary by a factor of at least 20.

  14. Prenatal exposure to selenium may protect against wheezing in children by the age of 3

    PubMed Central

    Chastang, Julie; Ibanez, Gladys; Annesi‐Maesano, Isabella

    2016-01-01

    Abstract Introduction It has been suggested that human in utero exposure to heavy metals such as selenium can reduce the prevalence of childhood asthma and allergic diseases. However, data on this topic are scarce. The objective of the present study was to assess the putative associations between maternal selenium level during pregnancy and the risk of asthma, wheezing, allergic rhinitis, and atopic dermatitis in children from the EDEN birth cohort by the age of 1 and 3 years. Methods Plasma selenium concentrations were measured in maternal blood during mid‐pregnancy (24–28 weeks of gestation) in 861 mothers. Cohort children were followed up from birth to 3 years using health questionnaires filled out by the parents for asthma, wheezing, allergic rhinitis, and atopic dermatitis. Maternal plasma selenium was related to the childhood outcomes by the age of 1 and 3 years. Results Our results showed a significant negative association between a high maternal plasma selenium level during pregnancy and the risk of wheezing in the child by the age of 1 and 3 years. However, maternal plasma selenium during pregnancy was not associated with the prevalence of asthma, allergic rhinitis or atopic dermatitis. Conclusions The results of this study suggest that the level of fetal exposure to maternal selenium could have an influence on the risk of wheezing in infancy and potentially on the risk of developing asthma later in life. PMID:28250923

  15. Solar Flare Track Exposure Ages in Regolith Particles: A Calibration for Transmission Electron Microscope Measurements

    NASA Technical Reports Server (NTRS)

    Berger, Eve L.; Keller, Lindsay P.

    2015-01-01

    Mineral grains in lunar and asteroidal regolith samples provide a unique record of their interaction with the space environment. Space weathering effects result from multiple processes including: exposure to the solar wind, which results in ion damage and implantation effects that are preserved in the rims of grains (typically the outermost 100 nm); cosmic ray and solar flare activity, which result in track formation; and impact processes that result in the accumulation of vapor-deposited elements, impact melts and adhering grains on particle surfaces. Determining the rate at which these effects accumulate in the grains during their space exposure is critical to studies of the surface evolution of airless bodies. Solar flare energetic particles (mainly Fe-group nuclei) have a penetration depth of a few millimeters and leave a trail of ionization damage in insulating materials that is readily observable by transmission electron microscope (TEM) imaging. The density of solar flare particle tracks is used to infer the length of time an object was at or near the regolith surface (i.e., its exposure age). Track measurements by TEM methods are routine, yet track production rate calibrations have only been determined using chemical etching techniques [e.g., 1, and references therein]. We used focused ion beam-scanning electron microscope (FIB-SEM) sample preparation techniques combined with TEM imaging to determine the track density/exposure age relations for lunar rock 64455. The 64455 sample was used earlier by [2] to determine a track production rate by chemical etching of tracks in anorthite. Here, we show that combined FIB/TEM techniques provide a more accurate determination of a track production rate and also allow us to extend the calibration to solar flare tracks in olivine.

  16. Cosmic Ray Exposure Ages of Stony Meteorites: Space Erosion or Yarkovsky?

    NASA Technical Reports Server (NTRS)

    Rubincam, David Parry

    2014-01-01

    Space erosion from dust impacts may set upper limits on the cosmic ray exposure (CRE) ages of stony meteorites. A meteoroid orbiting within the asteroid belt is bombarded by both cosmic rays and interplanetary dust particles. Galactic cosmic rays penetrate only the first few meters of the meteoroid; deeper regions are shielded. The dust particle impacts create tiny craters on the meteoroid's surface, wearing it away by space erosion (abrasion) at a particular rate. Hence a particular point inside a meteoroid accumulates cosmic ray products only until that point wears away, limiting CRE ages. The results would apply to other regolith-free surfaces in the solar system as well, so that abrasion may set upper CRE age limits which depend on the dusty environment. Calculations based on N. Divine's dust populations and on micrometeoroid cratering indicate that stony meteoroids in circular ecliptic orbits at 2 AU will record 21Ne CRE ages of approx.176 x 10(exp 6) years if dust masses are in the range 10(exp -21) - 10(exp -3) kg. This is in broad agreement with the maximum observed CRE ages of approx. 100 x 10(exp 6) years for stones. High erosion rates in the inner solar system may limit the CRE ages of Near-Earth Asteroids (NEAs) to approx. 120 x 10(exp 6) years. If abrasion should prove to be approx. 6 times quicker than found here, then space erosion may be responsible for many of the measured CRE ages of main belt stony meteorites. In that case the CRE ages may not measure the drift time to the resonances due to the Yarkovsky effects as in the standard scenario, and that for some reason Yarkovsky is ineffective.

  17. The confounded effects of age and exposure history in response to influenza vaccination.

    PubMed

    Mosterín Höpping, Ana; McElhaney, Janet; Fonville, Judith M; Powers, Douglas C; Beyer, Walter E P; Smith, Derek J

    2016-01-20

    Numerous studies have explored whether the antibody response to influenza vaccination in elderly adults is as strong as it is in young adults. Results vary, but tend to indicate lower post-vaccination titers (antibody levels) in the elderly, supporting the concept of immunosenescence-the weakening of the immunological response related to age. Because the elderly in such studies typically have been vaccinated against influenza before enrollment, a confounding of effects occurs between age, and previous exposures, as a potential extrinsic reason for immunosenescence. We conducted a four-year study of serial annual immunizations with inactivated trivalent influenza vaccines in 136 young adults (16 to 39 years) and 122 elderly adults (62 to 92 years). Compared to data sets of previously published studies, which were designed to investigate the effect of age, this detailed longitudinal study with multiple vaccinations allowed us to also study the effect of prior vaccination history on the response to a vaccine. In response to the first vaccination, young adults produced higher post-vaccination titers, accounting for pre-vaccination titers, than elderly adults. However, upon subsequent vaccinations the difference in response to vaccination between the young and elderly age groups declined rapidly. Although age is an important factor when modeling the outcome of the first vaccination, this term lost its relevance with successive vaccinations. In fact, when we examined the data with the assumption that the elderly group had received (on average) as few as two vaccinations prior to our study, the difference due to age disappeared. Our analyses therefore show that the initial difference between the two age groups in their response to vaccination may not be uniquely explained by immunosenescence due to ageing of the immune system, but could equally be the result of the different pre-study vaccination and infection histories in the elderly.

  18. The influence of age of lead exposure on adult gray matter volume.

    PubMed

    Brubaker, Christopher J; Dietrich, Kim N; Lanphear, Bruce P; Cecil, Kim M

    2010-06-01

    Childhood lead exposure is associated with decreased cognitive abilities and executive functioning localized within the prefrontal cortex. Several studies have observed stronger associations between blood lead measurements obtained later in life than earlier measures, but there are no imaging studies investigating the developmental trajectory of blood lead levels taken during childhood on adult gray matter volume. In this study, we recruited 157 adults (20.8+/-1.5 years of age) from the Cincinnati Lead Study to undergo high resolution volumetric magnetic resonance imaging. Adjusted voxel-wise regression analyses were performed for associations between adult gray matter volume loss and yearly mean blood lead levels from 1 to 6 years of age in the entire cohort and by sex. We observed significant inverse associations between gray matter volume loss and annual mean blood lead levels from 3 to 6 years of age. The extent of prefrontal gray matter associated with yearly mean blood lead levels increased with advancing age of the subjects. The inverse associations between gray matter volume loss and yearly mean blood lead measurements were more pronounced in the frontal lobes of men than women. Analysis of women yielded significantly weaker associations between yearly mean blood lead levels and gray matter volume at all ages than either men or the combined cohort of men and women together. These results suggest that blood lead concentrations obtained during later childhood demonstrate greater loss in gray matter volume than childhood mean or maximum values. The relationship between childhood blood lead levels and gray matter volume loss was predominantly observed in the frontal lobes of males. This study demonstrates that maximum blood lead levels do not fully account for gray matter changes associated with childhood lead exposure, particularly in the frontal lobes of young men.

  19. Chronology of glaciations in the Cantabrian Mountains (NW Iberia) during the Last Glacial Cycle based on in situ-produced 10Be

    NASA Astrophysics Data System (ADS)

    Rodríguez-Rodríguez, Laura; Jiménez-Sánchez, Montserrat; Domínguez-Cuesta, María José; Rinterknecht, Vincent; Pallàs, Raimon; Bourlès, Didier

    2016-04-01

    The mountain ranges of the Iberian Peninsula preserve a valuable record of past glaciations that may help reconstruct past atmospheric circulation patterns in response to cooling events in the North Atlantic Ocean. Available chronologies for the glacial record of the Cantabrian Mountains, which are mainly based on radiocarbon and luminescence dating of glacial-related sediments, suggest that glaciers recorded their Glacial Maximum (GM) during MIS 3 and experienced a later Last Glacial Maximum (LGM) advance. This LGM extent is not established yet, preventing a fair correlation with available Cosmic Ray Exposure (CRE) based chronologies for the glacial record of the Pyrenees and the Sistema Central. We present a glacial reconstruction and a 10Be CRE chronology for the Porma valley, in the southern slope of the central Cantabrian Mountains. Glacial evidence at the lowest altitudes correspond to erratic boulders and composite moraines whose minimum 10Be CRE age of 113.9 ± 7.1 ka suggests that glaciers were at their maximum extent during MIS 5d, most likely in response to the minima in summertime insolation of the Last Glacial Cycle. Recessional moraines preserved within the glacial maximum limits allow the assessment of subsequent glacier advances or stagnations. The most remarkable advance took place prior to 55.7 ± 4.0 ka (probably at the end of MIS 4), consistently with minimum radiocarbon ages previously reported for lacustrine glacial-related deposits in the Cantabrian Mountains. A limited number of 10Be CRE ages from a composite moraine suggest a possible advance of the Porma glacier coeval with the global LGM; the glacier front attributed to the LGM would be placed within the margins of the previous GM like in the western Pyrenees. Erratic boulders perched on an ice-moulded bedrock surface provided a mean 10Be CRE age of 17.7 ± 1.0 ka, suggesting that part of the recessional moraine sequence corresponds to minor advances or stagnations of the glacier fronts

  20. Lead Exposure and Tremor among Older Men: The VA Normative Aging Study

    PubMed Central

    Power, Melinda C.; Sparrow, David; Spiro, Avron; Hu, Howard; Louis, Elan D.; Weisskopf, Marc G.

    2015-01-01

    Background: Tremor is one of the most common neurological signs, yet its etiology is poorly understood. Case–control studies suggest an association between blood lead and essential tremor, and that this association is modified by polymorphisms in the δ-aminolevulinic acid dehydrogenase (ALAD) gene. Objective: We aimed to examine the relationship between lead and tremor, including modification by ALAD, in a prospective cohort study, using both blood lead and bone lead—a biomarker of cumulative lead exposure. Methods: We measured tibia (n = 670) and patella (n = 672) bone lead and blood lead (n = 807) among older men (age range, 50–98 years) in the VA Normative Aging Study cohort. A tremor score was created based on an approach using hand-drawing samples. ALAD genotype was dichotomized as ALAD-2 carriers or not. We used linear regression adjusted for age, education, smoking, and alcohol intake to estimate the associations between lead biomarkers and tremor score. Results: In unadjusted analyses, there was a marginal association between quintiles of all lead biomarkers and tremor scores (p-values < 0.13), which did not persist in adjusted models. Age was the strongest predictor of tremor. Among those younger than the median age (68.9 years), tremor increased significantly with blood lead (p = 0.03), but this pattern was not apparent for bone lead. We did not see modification by ALAD or an association between bone lead and change in tremor score over time. Conclusion: Our results do not strongly support an association between lead exposure and tremor, and suggest no association with cumulative lead biomarkers, although there is some suggestion that blood lead may be associated with tremor among the younger men in our cohort. Citation: Ji JS, Power MC, Sparrow D, Spiro A III, Hu H, Louis ED, Weisskopf MG. 2015. Lead exposure and tremor among older men: the VA Normative Aging Study. Environ Health Perspect 123:445–450; http://dx.doi.org/10.1289/ehp.1408535

  1. Environmental exposure of the pediatric age groups in Cairo City and its suburbs to cadmium pollution.

    PubMed

    Hossny, E; Mokhtar, G; El-Awady, M; Ali, I; Morsy, M; Dawood, A

    2001-06-12

    In a trial to assess the exposure of subjects in the pediatric age group to cadmium (Cd) pollution, serum Cd was estimated by atomic absorption spectrometry in 405 subjects, birth-18 years old, from Cairo City and its suburbs. Serum Cd mean concentrations were: 0.92 microg/l in 32 neonates (birth-4 weeks); 1.33 microg/l in 70 infants (4 weeks-2 years); 1.11 microg/l in 100 children in the preschool period (2-6 years); 1.34 microg/l in 103 primary school children (6-12 years); and 1.24 microg/l in 100 adolescents (12-18 years). In neonates, serum Cd was higher in babies with weights and heights that remained below the 5th percentile for age. Breast-fed infants had a serum Cd geometric mean level (1.25 microg/l) that was not in accordance to that of their mothers' milk (0.52 microg/l, P < 0.001), suggesting alternative routes of exposure. Environmental tobacco-smoke exposure was the most important determinant of Cd status in the school-aged children, the geometric mean being 1.42 microg/l in passive smokers vs. 1.2 microg/l in non-exposed children (P < 0.05). Moreover, adolescents who were active smokers had a significantly higher serum Cd level (1.7 microg/l) as compared to non-smokers (1.2 microg/l). Gender did influence the Cd status in adolescents, being higher among males, probably related to smoking, or to the difference in lifestyle of adolescents according to gender in the community. Alpha-1-microglobulinuria was accompanied by a higher serum Cd concentration in the group of adolescents only, suggesting a subclinical renal effect after several years of cumulative exposure. The residential classification, whether urban or suburban, did not influence the serum Cd status; neither did the present or past history of bronchial asthma. These findings certainly justify further evaluation of the problem of Cd pollution among Cairene individuals, knowing the long-term consequences of exposure to it. Systematic efforts for the proper disposal of Cd wastes and prevention

  2. Early exposure to ethanol differentially affects ethanol preference at adult age in two inbred mouse strains.

    PubMed

    Molet, Jenny; Bouaziz, Elodie; Hamon, Michel; Lanfumey, Laurence

    2012-08-01

    Although the acute effects of ethanol exposure on brain development have been extensively studied, the long term consequences of juvenile ethanol intake on behavior at adult age, regarding especially ethanol consumption, are still poorly known. The aim of this study was to analyze the consequences of ethanol ingestion in juvenile C57BL/6J and DBA/2J mice on ethanol intake and neurobiological regulations at adulthood. Mice were given intragastric ethanol at 4 weeks of age under different protocols and their spontaneous ethanol consumption was assessed in a free choice paradigm at adulthood. Both serotonin 5-HT(1A) and cannabinoid CB1 receptors were investigated using [(35)S]GTP-γ-S binding assay for the juvenile ethanol regimens which modified adult ethanol consumption. In DBA/2J mice, juvenile ethanol ingestion dose-dependently promoted adult spontaneous ethanol consumption. This early ethanol exposure enhanced 5-HT(1A) autoreceptor-mediated [(35)S]GTP-γ-S binding in the dorsal raphe nucleus and reduced CB1 receptor-mediated G protein coupling in both the striatum and the globus pallidus at adult age. In contrast, early ethanol ingestion by C57BL/6J mice transiently lowered spontaneous ethanol consumption and increased G protein coupling of postsynaptic 5-HT(1A) receptors in the hippocampus but had no effect on CB1 receptors at adulthood. These results show that a brief and early exposure to ethanol can induce strain-dependent long-lasting changes in both behavior toward ethanol and key receptors of central 5-HT and CB systems in mice.

  3. 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).

  4. Perinatal dioxin exposure and the neurodevelopment of Vietnamese toddlers at 1 year of age.

    PubMed

    Pham, Tai The; Nishijo, Muneko; Nguyen, Anh Thi Nguyet; Tran, Nghi Ngoc; Van Hoang, Luong; Tran, Anh Hai; Nguyen, Trung Viet; Nishijo, Hisao

    2015-12-01

    Dioxin concentrations remain elevated in both the environment and in humans residing near former US Air Force bases in South Vietnam. This may potentially have adverse health effects, particularly on infant neurodevelopment. We followed 214 infants whose mothers resided in a dioxin-contaminated area in Da Nang, Vietnam, from birth until 1 year of age. Perinatal exposure to dioxins was estimated from toxic equivalent (TEQ) levels of polychlorinated dibenzodioxins and polychlorinated dibenzofurans (PCDDs/Fs-TEQ), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TetraCDD) concentrations in breast milk. In infants, daily dioxin intake (DDI) was used as an index of postnatal exposure through breastfeeding. Neurodevelopment of toddlers was assessed using the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III). No significant differences in neurodevelopmental scores were exhibited for cognitive, language or motor functions between four exposure groups of PCDDs/Fs-TEQ or 2,3,7,8-TetraCDD. However, social-emotional scores were decreased in the high PCDDs/Fs-TEQ group and the high 2,3,7,8-TetraCDD group compared with those with mild exposure, after adjusting for confounding factors. Cognitive scores in the mild, moderate, and high DDI groups were significantly higher than those in low DDI group, but there were no differences in cognitive scores among the three higher DDI groups. These results suggest that perinatal exposure to dioxins may affect social-emotional development of 1-year-old toddlers, without diminishing global neurodevelopmental function.

  5. In situ produced 10Be depth profiles and luminescence data tracing climatic and tectonic control on terrace formation, Danube River, Central Europe, Hungary

    NASA Astrophysics Data System (ADS)

    Ruszkiczay-Rüdiger, Zsófia; Braucher, Régis; Novothny, Ágnes; Csillag, Gábor; Fodor, László; Molnár, Gábor; Madarász, Balázs; Aster Team

    2015-04-01

    The terrace sequence of the Hungarian part of the Danube valley preserves a record of varying tectonic uplift rates along the river course and throughout several climate stages. To establish the chronology of formation of these terraces, two different dating methods on alluvial terraces were used: 1) in situ produced cosmogenic 10Be, which yield the time of abandonment of the terrace and 2) luminescence dating, which provides burial ages of the sediment. In situ produced cosmogenic 10Be samples originated from vertical depth profiles to enable the determination of both the exposure time and the denudation rate at each locality. We used Monte Carlo approach to model the denudation rate-corrected exposure ages. Post-IR IRSL measurements were carried out on K-feldspar samples to obtain the ages of sedimentation. The highest and oldest terrace remnants (tIV-VI) yield a minimum 10Be exposure age of 800 ka close to MIS 22, the onset of major continental glaciations of Quaternary age, suggesting climatic signal of the abandonment of the uppermost terrace levels. For the lower terraces it was possible to reveal close correlation with MIS stages using IRSL ages. The new chronology enables the distinction of tIIb (60-110 ka; MIS 4-5d) and tIIIa (130-190 ka; MIS 6) in the study area. Surface denudation rates were well constrained by the cosmogenic 10Be depth profiles between 5.9 m/Ma and 10.0 m/Ma for all terraces. Maximum incision rates of the Danube were calculated for middle and late Pleistocene times. These rates were increasing from west to east, toward the more elevated Transdanubian Range from 0.05 mm/a to 0.12 mm/a. Incision rates derived from the age of the low terraces (0.13 mm/a) may suggest a slight acceleration of uplift towards present. Our research was supported by the OTKA PD83610, PD100315, NK60455, K062478, K83150 and F042799, the French-Hungarian Balaton-Tét Project (FR-32/2007; TÉT_11-2-2012-0005), the Bolyai János Scholarship of the Hungarian Academy

  6. 26Al/10Be burial dating of Xujiayao-Houjiayao site in Nihewan Basin, northern China.

    PubMed

    Tu, Hua; Shen, Guanjun; Li, Haixu; Xie, Fei; Granger, Darryl E

    2015-01-01

    The Xujiayao-Houjiayao site in Nihewan Basin is among the most important Paleolithic sites in China for having provided a rich collection of hominin and mammalian fossils and lithic artifacts. Based on biostratigraphical correlation and exploratory results from a variety of dating methods, the site has been widely accepted as early Upper Pleistocene in time. However, more recent paleomagnetic analyses assigned a much older age of ∼500 ka (thousand years). This paper reports the application of 26Al/10Be burial dating as an independent check. Two quartz samples from a lower cultural horizon give a weighted mean age of 0.24 ± 0.05 Ma (million years, 1σ). The site is thus younger than 340 ka at 95% confidence, which is at variance with the previous paleomagnetic results. On the other hand, our result suggests an age of older than 140 ka for the site's lower cultural deposits, which is consistent with recent post-infrared infrared stimulated luminescence (pIR-IRSL) dating at 160-220 ka.

  7. Authigenic 10Be/9Be ratios and 10Be-fluxes (230Thxs-normalized) in central Baffin Bay sediments during the last glacial cycle: Paleoenvironmental implications

    NASA Astrophysics Data System (ADS)

    Simon, Quentin; Thouveny, Nicolas; Bourlès, Didier L.; Nuttin, Laurence; Hillaire-Marcel, Claude; St-Onge, Guillaume

    2016-05-01

    Authigenic 10Be/9Be ratios and 10Be-fluxes reconstructed using the 230Thxs normalization, proxies of the cosmogenic radionuclide 10Be production rate in the atmosphere, have been measured in a sedimentary core from Baffin Bay (North Atlantic) spanning the last 136 ka BP. The normalization applied on the exchangeable (authigenic) 10Be concentrations using the authigenic 9Be isotope and 230Thxs methods yield equivalent results strongly correlated with sedimentological parameters (grain-size and mineralogy). Lower authigenic beryllium (Be) concentrations and 10Be/9Be ratios are associated with coarse-grained carbonate-rich layers, while higher authigenic Be values are related to fine-grained felspar-rich sediments. This variability is due to: i) sediment composition control over beryllium-scavenging efficiency and, ii) glacial history that contributed to modify the 10Be concentration in Baffin Bay by input and boundary scavenging condition changes. Most paleo-denudation rates inferred from the 10Be/9Be ratio vary weakly around 220 ± 76 tons.km-2.yr-1 (0.09 ± 0.03 mm.yr-1) corresponding to relatively steady weathering fluxes over the last glacial cycle except for six brief intervals characterized by sharp increases of the denudation rate. These intervals are related to ice-surging episodes coeval with Heinrich events and the last deglaciation period. An average freshwater flux of 180.6 km3.yr-1 (0.006 Sv), consistent with recent models, has been calculated in order to sustain glacially-derived 10Be inputs into Baffin Bay. It is concluded that in such environments, the authigenic 10Be measured mainly depends on climatic effects related to the glacial dynamics, which masks the 10Be production variation modulated by geomagnetic field changes. Altogether, these results challenge the simple interpretation of 10Be-concentration variation as a proxy of Interglacial/Glacial (interstadial/stadial) cycles in Arctic and sub-Arctic regions. They rather suggest the effect of

  8. Interaction between age of irradiation and age of testing in the disruption of operant performance using a ground-based model for exposure to cosmic rays

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Exposure to HZE particles produces deficits in cognitive performance. While previous research has shown a progressive deterioration in cognitive performance in radiated rats as a function of age, the present experiment was designed to evaluate the effects of age of irradiation independently of the ...

  9. 10Be depth-profile dating of glaciofluvial sediments in the northern Alpine Foreland

    NASA Astrophysics Data System (ADS)

    Claude, Anne; Akçar, Naki; Ivy-Ochs, Susan; Schlunegger, Fritz; Kubik, Peter; Christl, Marcus; Vockenhuber, Christof; Dehnert, Andreas; Rahn, Meinert; Schlüchter, Christian

    2016-04-01

    10Be depth-profile dating is based on the fact that nuclide production is decreasing as an exponential function of depth. This method requires collecting at least four sediment samples in a vertical profile. The obtained nuclide concentrations are plotted against depth and fitted depth-profiles to the measured dataset. The age is then calculated based on the best-fit. The requirements for this method are the following: sampling geological units in artificial outcrops with minimum thickness of soil (less than around 80 cm), preferably with a flat-topped landform in order to guarantee that the uppermost surface of the deposit remains as unmodified as possible and is related to a defined geomorphologic process. Additionally at least one sample, preferably three, from the uppermost one meter of the profile as the exponential decrease mainly occurs around this depth. No sample is collected from the overlying soil. In this study, we aim to establish the chronology of the oldest Quaternary sediments in the northern Alpine Foreland using depth-profile dating with 10Be. These ages contribute to the understanding of the Quaternary landscape evolution of the Alpine Foreland. Here, we unravel the chronology of five sites at different morphostratigraphic positions: Mandach and Ängi (canton Aargau), Stadlerberg and Irchel (canton Zurich) and Rechberg (Germany, 4 km from the border to Switzerland). All sites are abandoned gravel pits and at each site we collected between four and seven sediment samples. First results yielded chronologies between 0.8 and 2 Ma for these glaciofluvial deposits. Our study shows that this relatively new method is successful when the geological setting matches the methodological requirements.

  10. Association of Prenatal Ibuprofen Exposure with Birth Weight and Gestational Age: A Population-Based Sibling Study

    PubMed Central

    Nezvalová-Henriksen, Kateřina; Wood, Mollie; Spigset, Olav; Nordeng, Hedvig

    2016-01-01

    Objectives Three studies so far have investigated the effect of prenatal non-steroidal anti-inflammatory drug (NSAID) exposure on birth weight and gestational age. The aim in this study was to evaluate the association of prenatal ibuprofen with birth weight and gestational age at birth, using a sibling design in an attempt to adjust for the possibility of familial confounding. Design Using data from the Norwegian Mother and Child Cohort Study (MoBa) and the Medical Birth Registry of Norway (MBRN), we identified 28 597 siblings, of whom 1080 were prenatally exposed to ibuprofen and 26 824 were not exposed to any NSAID. Random and fixed effects models with propensity score adjustment were used to evaluate the effects of ibuprofen exposure on birth weight and gestational age. Results Ibuprofen exposure during the first trimester was associated with a decrease in birth weight of 79 grams (95% confidence interval -133 to -25 grams). In contrast, second and/or third trimester exposure, and duration of exposure had no impact on the effect estimates. We found no association between ibuprofen exposure and gestational age at birth. Conclusions Our results suggest that prenatal exposure to ibuprofen during the first trimester is associated with a slight decrease in birth weight. The association does not seem to be attributable to shared genetics and family environment, and could be explained by either exposure to ibuprofen, or to non-shared confounding between pregnancies. PMID:27936000

  11. Effect of Mitochondrial Oxidative Stress and Age on the Signaling Pathway of Ultrafine Particulate Matter Exposure in Murine Aorta

    EPA Science Inventory

    Epidemiological studies have linked ultrafine particulate matter (PM) exposure and adverse cardiovascular events. PM-induced oxidative stress is believed to be a key mechanism contributing to the adverse short-term vascular effects of air pollution exposure. Advanced age is one ...

  12. Loess 10Be evidence for an asynchronous Brunhes-Matuyama magnetic polarity reversal

    NASA Astrophysics Data System (ADS)

    Zhou, Weijian; Beck, J. Warren; Kong, Xianghui; An, Zhisheng; Qiang, Xiaoke; Wu, Zhenkun; Xian, Feng; Ao, Hong

    2015-04-01

    In Chinese loess the Brunhes-Matuyama (B-M) geomagnetic reversal appears to occur about 25 ka prior to the established axial dipole reversal age found in many marine sediments, i.e., in Chinese loess this magnetic reversal boundary is found in glacial loess unit L8 which is thought to be correlated with Marine Isotope Stage 20 (MIS 20), in marine sediment records, however, this boundary is commonly found in interglacial period of MIS 19 (Tauxe et al., 1996; Zhou and Shackleton, 1999), leading to the debate on uncertainties of paleoclimatic correlation between the Chinese loess-paleosol sequences and marine sediments (Wang et al., 2006; Liu et al., 2008; Jin and Liu, 2011). Based on this issue, here we propose to use the cosmogenic 10Be to address this conundrum. 10Be is a long-lived radionuclide produced in the atmosphere by cosmic ray spallation reactions and carried to the ground attached to aerosols. Its atmospheric production rate is inversely proportional to the geomagnetic field intensity (Masarik and Beer, 1999). This allows us to reconstruct past geomagnetic field intensity variations using 10Be concentrations recorded in different sedimentary archives. We carried out both the 10Be studies and paleogeomagnetic measurements in Luochuan and Xifeng sections in Chinese Loess Plateau. Both loess profiles show that 10Be production rate was at a maximum-an indication of the dipole field reversal-at ca. 780 ± 3 ka BP., in paleosol unit S7 corresponding to MIS 19, proving that the timing of B-M reversal recorded in Chinese loess is synchronous with that seen in marine records (Tauxe et al., 1996). These results reaffirmed the conventional paleoclimatic correlation of loess-paleosol sequences with marine isotope stages and the standard loess timescale as correct. However, it is ~25 ka younger than the age (depth) of the paleogeomagnetic measurements which show that the B-M boundary is in L8 in these two Chinese loess-paleosol sequences, demonstrating that loess

  13. Prenatal cocaine and/or nicotine exposure produces depression and anxiety in aging rats.

    PubMed

    Sobrian, Sonya K; Marr, Lara; Ressman, Katherine

    2003-05-01

    The adult use of cocaine and nicotine has been linked to depression and/or anxiety. Changes in emotional behavior were assessed using behavioral paradigms developed as animal analogs of psychiatric disorders in 12-14 month old Sprague-Dawley rats exposed daily on gestational days 8-20 to cocaine and nicotine, either alone or in combination. Results from the elevated plus maze (EPM), used to assess anxiety-related behaviors, indicated that offspring prenatally exposed to either high-dose cocaine (40 mg/kg/day) or high-dose nicotine (5.0 mg/kg/day) were less timid/more impulsive. Animals from these two groups spent the most time on the open arms, and had the highest percentage of entries into the open arms of the EPM. Combined in utero exposure to cocaine and nicotine nullified these effects. Cocaine challenge (20 mg/kg) did not interact with prenatal treatment, but increased activity on all arms of the EPM in all groups. Sucrose preference was used as a measure of anhedonia, a cardinal symptom of depressive illness. Reduced sucrose preference was seen only in the group of offspring prenatally exposed to high-dose cocaine (40 mg/kg) plus low-dose nicotine (2.5 mg/kg/day). Exposure to a water-deprivation stress normalized sucrose preference in this group, without altering preference or intake in the other prenatal treatment groups. Transient hyperactivity was seen in the offspring of dams treated with high-dose nicotine, an effect that was again reversed in combined drug groups. Traditional gender differences in activity levels and sucrose intake, that is, females greater than males, were still evident in this population of aging rats. These data indicate that prenatal exposure to cocaine and/or nicotine has long-term effects on emotional behavior. Combined drug exposure contributed to the development of depressive symptoms, but not anxiety-like behavior, in a dose-dependent manner. In contrast, exposure to high doses of either drug alone reduced cautionary behavior

  14. Amplitude and timing of the Laschamp geomagnetic dipole low from the global atmospheric 10Be overproduction: Contribution of authigenic 10Be/9Be ratios in west equatorial Pacific sediments

    NASA Astrophysics Data System (ADS)

    MéNabréAz, L.; BourlèS, D. L.; Thouveny, N.

    2012-11-01

    Authigenic 10Be/9Be ratios were measured along a sediment core collected in the west equatorial Pacific in order to reconstruct cosmogenic 10Be production variations near the equator, where the geomagnetic modulation is maximum. From 60 to 20 ka, the single significant 10Be production impulse recorded at 41 ka results from the geomagnetic dipole low that triggered the Laschamp excursion. No significant 10Be overproduction signature is recorded at the age of the Mono Lake excursion (˜34 ka). A compilation of authigenic 10Be/9Be records obtained from sediments was averaged over a 1 kyr window and compared with the 1 kyr averaged 10Be flux record of Greenland ice cores. Their remarkable similarity demonstrates that 10Be production is globally modulated by geomagnetic dipole variations and redistributed by atmosphere dynamics. After calibration using absolute values of the virtual dipole moment drawn from paleomagnetic database, the authigenic 10Be/9Be stack allows reconstructing the geomagnetic dipole moment variations over the 20-50 ka time interval. Between 48 and 41 ka, the dipole moment collapsed at a rate of -1.5 × 1022 A m2 kyr-1, which will be an interesting criterion for the assessment of the loss rate of the historical field and the comparison of dipole moment loss prior to excursions and reversals. After a 2 kyr duration of the minimum dipole moment (˜1 × 1022 A m2), a slow increase started at 39 ka, progressively reaching 5 × 1022 A m2 at 20 ka. The absence of a significant dipole moment drop at 34 ka, the age of the Mono lake excursion, suggests that the duration and amplitude of the dipole weakening cannot be compared with that of the Laschamp. This study provides a reliable basis to model the production of radiocarbon and in situ cosmogenic nuclides and to improve the calibration of these dating methods.

  15. New Cosmogenic Beryllium-10 Exposure-Age Limits on Terminal Moraines of the Last Glaciation in the Bear River Drainage, Uinta Mountains, Utah

    NASA Astrophysics Data System (ADS)

    Laabs, B. J.; Munroe, J. S.; Rosenbaum, J. G.; Refsnider, K. A.

    2006-12-01

    The Uinta Mountains were occupied by numerous glaciers during marine oxygen-isotope stage 2 (MIS 2). Reconstructions for the last glaciation reveal that central and eastern valleys in the Uintas contained discrete valley glaciers, many of which advanced beyond the mountain front. Cosmogenic exposure-age limits on two moraines in the south-central part of the range indicate that glaciers retreated from their maximum extents at 16.8 ± 0.7 ka (Munroe et al., 2006), up to 2000 years later than glaciers elsewhere in the Middle and Southern Rockies. These ages suggest that deglaciation of the Uintas was approximately synchronous with the hydrologic fall of Lake Bonneville (at ~16 cal. ka), which implies that glaciers and the lake responded to the same regional climatic forcing. Glacial reconstructions further indicate that glaciers in the western Uintas, nearest to the lake, had equilibrium-line altitudes as much as 600 m lower than glaciers farther east. This evidence suggests that Lake Bonneville may have amplified moisture in the western Uinta Mountains by providing lake-effect precipitation to valleys located immediately downwind. To further investigate this hypothesis, we acquired cosmogenic 10Be surface-exposure ages from a terminal moraine in the Bear River drainage in the northwestern Uinta Mountains. This valley was occupied by outlet glaciers of the Provo Ice Field (of Refsnider, 2006), which covered an area of about 685 km2 and drained via several valleys in the Uintas. Cosmogenic-exposure ages of moraine boulders range from 24.5 ± 2.5 ka to 19.0 ± 3.5 ka (± 2σ) with an error-weighted mean of 21.5 ± 1.4 ka (n = 7), which we interpret to represent a minimum age of deglaciation in the Bear River drainage. Radiocarbon ages of glacial flour in sediment from Bear Lake, a large lake downstream of the glaciated area, are generally consistent with cosmogenic-exposure ages and indicate that deglaciation began at about 24 cal. ka (Rosenbaum et al., 2005). When

  16. The Relationship Between Cosmic-Ray Exposure Ages And Mixing Of CM Chondrite Lithologies

    NASA Technical Reports Server (NTRS)

    Zolensky, M. E.; Takenouchi, A.; Gregory, T.; Nishiizumi, K.; Caffee, M.; Velbel, M. A.; Ross, K.; Zolensky, A.; Le, L.; Imae, N.; Yamaguchi, A.; Mikouchi, T.

    2017-01-01

    Carbonaceous (C) chondrites are primitive materials probably deriving from C, P and D asteroids, and as such potentially include samples and analogues of the target asteroids of the Dawn, Hayabusa2 and OSIRIS-Rex missions. Foremost among the C chondrites are the CM chondrites, the most common type, and which have experienced the widest range of early solar system processes including oxidation, hydration, metamorphism, and impact shock deformation, often repeatedly or cyclically [1]. To track the activity of these processes in the early solar system, it is critical to learn how many separate bodies are represented by the CMs. Nishiizumi and Caffee [2] have reported that the CMs are unique in displaying several distinct peaks for cosmic-ray exposure (CRE) age groups, and that excavation from significant depth and exposure as small entities in space is the best explanation for the observed radionuclide data. There are either 3 or 4 CRE groups for CMs (Fig.1). We decided to systematically characterize the petrography in each of the CRE age groups to determine whether the groups have significant petrographic differences with these reflecting different parent asteroid geological processing or multiple original bodies. We previously re-ported preliminary results of our work [3], however we have now reexamined these meteorites from the perspective of brecciation, with interesting new results.

  17. The importance of age and smoking in evaluating adverse cytogenetic effects of exposure to environmental agents

    SciTech Connect

    Tucker, J.D.; Moore, D.H. II

    1995-08-01

    Fluorescence in situ hybridization with chromosome-specific composite DNA probes (``chromosome painting``) is a reliable and efficient method for detecting structural chromosome aberrations. Painting is now being used to quantify chromosome damage in many human populations. In one such study we evaluated 91 unexposed people ranging in age from birth (cord bloods) to 79. We established a baseline frequency of stable aberrations that showed a highly significant curvi-linear increase with age (p < 0.00001) that accounted for 70% of the variance between donors. The magnitude of this effect illustrates the importance of understanding the cytogenetic changes that occur with age, which is particularly important for quantifying the effects of prior adverse environmental, occupational, or accidental exposure. In this paper we use the data obtained in our previous study to characterize the distribution of stable aberrations by age and pack-years of cigarette smoking. We also provide estimates of the number of cell equivalents that need to be scored to detect a given increase in aberrations above the background level surveyed in this population.

  18. Exposure to radiation accelerates normal brain aging and produces deficits in spatial learning and memory

    NASA Astrophysics Data System (ADS)

    Shukitt-Hale, B.; Casadesus, G.; Carey, A.; Rabin, B. M.; Joseph, J. A.

    Previous studies have shown that radiation exposure, particularly to particles of high energy and charge (HZE particles), produces deficits in spatial learning and memory. These adverse behavioral effects are similar to those seen in aged animals. It is possible that these shared effects may be produced by the same mechanism; oxidative stress damage to the central nervous system caused by an increased release of reactive oxygen species is likely responsible for the deficits seen in aging and following irradiation. Both aged and irradiated rats display cognitive impairment in tests of spatial learning and memory such as the Morris water maze and the radial arm maze. These rats have decrements in the ability to build spatial representations of the environment and they utilize non-spatial strategies to solve tasks. Furthermore, they show a lack of spatial preference, due to a decline in the ability to process or retain place (position of a goal with reference to a "map" provided by the configuration of numerous cues in the environment) information. These declines in spatial memory occur in measures dependent on both reference and working memory, and in the flexibility to reset mental images. These results show that irradiation with high-energy particles produces age-like decrements in cognitive behavior that may impair the ability of astronauts to perform critical tasks during long-term space travel beyond the magnetosphere. Supported by NASA Grants NAG9-1190 and NAG9-1529

  19. Age-dependent tissue-specific exposure of cell phone users

    NASA Astrophysics Data System (ADS)

    Christ, Andreas; Gosselin, Marie-Christine; Christopoulou, Maria; Kühn, Sven; Kuster, Niels

    2010-04-01

    The peak spatial specific absorption rate (SAR) assessed with the standardized specific anthropometric mannequin head phantom has been shown to yield a conservative exposure estimate for both adults and children using mobile phones. There are, however, questions remaining concerning the impact of age-dependent dielectric tissue properties and age-dependent proportions of the skull, face and ear on the global and local absorption, in particular in the brain tissues. In this study, we compare the absorption in various parts of the cortex for different magnetic resonance imaging-based head phantoms of adults and children exposed to different models of mobile phones. The results show that the locally induced fields in children can be significantly higher (>3 dB) in subregions of the brain (cortex, hippocampus and hypothalamus) and the eye due to the closer proximity of the phone to these tissues. The increase is even larger for bone marrow (>10 dB) as a result of its significantly high conductivity. Tissues such as the pineal gland show no increase since their distances to the phone are not a function of age. This study, however, confirms previous findings saying that there are no age-dependent changes of the peak spatial SAR when averaged over the entire head.

  20. Adolescent bisphenol-A exposure decreases dendritic spine density: role of sex and age.

    PubMed

    Bowman, Rachel E; Luine, Victoria; Khandaker, Hameda; Villafane, Joseph J; Frankfurt, Maya

    2014-11-01

    Bisphenol-A (BPA), a common environmental endocrine disruptor, modulates estrogenic, androgenic, and antiandrogenic effects throughout the lifespan. We recently showed that low dose BPA exposure during adolescence increases anxiety and impairs spatial memory independent of sex. In this study, six week old Sprague Dawley rats (n=24 males, n=24 females) received daily subcutaneous injections (40 µg/kg bodyweight) of BPA or vehicle for one week. Serum corticosterone levels in response to a 1 h restraint stress and spine density were examined at age 7 (cohort 1) and 11 (cohort 2) weeks. Adolescent BPA exposure did not alter stress dependent corticosterone responses but decreased spine density on apical and basal dendrites of pyramidal cells in the medial prefrontal cortex (mPFC) and hippocampal CA1 region (CA1). Sex differences in spine density were observed on basal dendrites of the mPFC and CA1 with females having greater spine density than males. This sex difference was further augmented by both age and treatment, with results indicating that BPA-dependent decreases in spine density were more pronounced in males than females on mPFC basal dendrites. Importantly, the robust neuronal alterations were observed in animals exposed to BPA levels below the current U.S.E.P.A. recommended safe daily limit. These results are the first demonstrating that BPA given during adolescence leads to enduring effects on neural morphology at adulthood. Given that humans are routinely exposed to low levels of BPA through a variety of sources, the decreased spine density reported in both male and female rats after BPA exposure warrants further investigation.

  1. Head impact exposure in youth football: middle school ages 12-14 years.

    PubMed

    Daniel, Ray W; Rowson, Steven; Duma, Stefan M

    2014-09-01

    The head impact exposure experienced by football players at the college and high school levels has been well documented; however, there are limited data regarding youth football despite its dramatically larger population. The objective of this study was to investigate head impact exposure in middle school football. Impacts were monitored using a commercially available accelerometer array installed inside the helmets of 17 players aged 12-14 years. A total of 4678 impacts were measured, with an average (±standard deviation) of 275 ± 190 impacts per player. The average of impact distributions for each player had a median impact of 22 ± 2 g and 954 ± 122 rad/s², and a 95th percentile impact of 54 ± 9 g and 2525 ± 450 rad/s². Similar to the head impact exposure experienced by high school and collegiate players, these data show that middle school football players experience a greater number of head impacts during games than practices. There were no significant differences between median and 95th percentile head acceleration magnitudes experienced during games and practices; however, a larger number of impacts greater than 80 g occurred during games than during practices. Impacts to the front and back of the helmet were most common. Overall, these data are similar to high school and college data that have been collected using similar methods. These data have applications toward youth football helmet design, the development of strategies designed to limit head impact exposure, and child-specific brain injury criteria.

  2. Age Induced Effects on ESD Characteristics of Solar Array Coupons After Combined Space Environmental Exposures

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth H.; Schneider, Todd A.; Vaughn, Jason A.; Hoang, Bao; Funderburk, Victor V.; Wong, Frankie; Gardiner, George

    2012-01-01

    A set of multi-junction GaAs/Ge solar array test coupons provided by Space Systems/Loral were subjected to a sequence of 5-year increments of combined space environment exposure tests. The test coupons capture an integrated design intended for use in a geosynchronous (GEO) space environment. A key component of this test campaign is performing electrostatic discharge (ESD) tests in the inverted gradient mode. The protocol of the ESD tests is based on the ISO standard for ESD testing on solar array panels [ISO-11221]. The test schematic in the ISO reference has been modified with Space System/Loral designed circuitry to better simulate the on-orbit operational conditions of its solar array design. Part of the modified circuitry is to simulate a solar array panel coverglass flashover discharge. All solar array coupons used in the test campaign consist of four cells constructed to form two strings. The ESD tests were performed at the beginning-of-life (BOL) and at each 5-year environment exposure point until end-of-life (EOL) at 15 years. The space environmental exposure sequence consisted of ultra-violet radiation, electron/proton particle radiation, thermal cycling, and Xenon ion thruster plume erosion. This paper describes the ESD test setup and the importance of the electrical test design in simulating the on-orbit operational conditions. Arc inception voltage results along with ESD test behavior from the BOL condition through the 15th year age condition are discussed. In addition, results from a Xenon plasma plume exposure test with an EOL coupon under the full ESD test condition will be discussed.

  3. SOCIAL CONSEQUENCES OF ETHANOL: IMPACT OF AGE, STRESS AND PRIOR HISTORY OF ETHANOL EXPOSURE

    PubMed Central

    Varlinskaya, Elena I.; Spear, Linda P.

    2014-01-01

    The adolescent period is associated with high significance of interactions with peers, high frequency of stressful situations, and high rates of alcohol use. At least two desired effects of alcohol that may contribute to heavy and problematic drinking during adolescence are its abilities to both facilitate interactions with peers and to alleviate anxiety, perhaps especially anxiety seen in social contexts. Ethanol-induced social facilitation can be seen using a simple model of adolescence in the rat, with normal adolescents, but not their more mature counterparts, demonstrating this ethanol-related social facilitation. Prior repeated stress induces expression of ethanol-induced social facilitation in adults and further enhances socially facilitating effects of ethanol among adolescent rats. In contrast, under normal circumstances, adolescent rats are less sensitive than adults to the social inhibition induced by higher ethanol doses and are insensitive to the socially anxiolytic effects of ethanol. Sensitivity to the socially anxiolytic effects of ethanol can be modified by prior stress or ethanol exposure at both ages. Shortly following repeated restraint or ethanol exposure, adolescents exhibit social anxiety-like behavior, indexed by reduced social preference, and enhanced sensitivity to the socially anxiolytic effects of ethanol, indexed through ethanol-associated reinstatement of social preference in these adolescents. Repeated restraint, but not repeated ethanol, induces similar effects in adults as well, eliciting social anxiety-like behavior and increasing their sensitivity to the socially anxiolytic effects of acute ethanol; the stressor also decreases sensitivity of adults to ethanol-induced social inhibition. The persisting consequences of early adolescent ethanol exposure differ from its immediate consequences, with males exposed early in adolescence, but not females or those exposed later in adolescence, showing social anxiety-like behavior when tested

  4. Social consequences of ethanol: Impact of age, stress, and prior history of ethanol exposure.

    PubMed

    Varlinskaya, Elena I; Spear, Linda P

    2015-09-01

    The adolescent period is associated with high significance of interactions with peers, high frequency of stressful situations, and high rates of alcohol use. At least two desired effects of alcohol that may contribute to heavy and problematic drinking during adolescence are its abilities to both facilitate interactions with peers and to alleviate anxiety, perhaps especially anxiety seen in social contexts. Ethanol-induced social facilitation can be seen using a simple model of adolescence in the rat, with normal adolescents, but not their more mature counterparts, demonstrating this ethanol-related social facilitation. Prior repeated stress induces expression of ethanol-induced social facilitation in adults and further enhances socially facilitating effects of ethanol among adolescent rats. In contrast, under normal circumstances, adolescent rats are less sensitive than adults to the social inhibition induced by higher ethanol doses and are insensitive to the socially anxiolytic effects of ethanol. Sensitivity to the socially anxiolytic effects of ethanol can be modified by prior stress or ethanol exposure at both ages. Shortly following repeated restraint or ethanol exposure, adolescents exhibit social anxiety-like behavior, indexed by reduced social preference, and enhanced sensitivity to the socially anxiolytic effects of ethanol, indexed through ethanol-associated reinstatement of social preference in these adolescents. Repeated restraint, but not repeated ethanol, induces similar effects in adults as well, eliciting social anxiety-like behavior and increasing their sensitivity to the socially anxiolytic effects of acute ethanol; the stressor also decreases sensitivity of adults to ethanol-induced social inhibition. The persisting consequences of early adolescent ethanol exposure differ from its immediate consequences, with males exposed early in adolescence, but not females or those exposed later in adolescence, showing social anxiety-like behavior when tested

  5. Meteoric 10Be in soil profiles - A global meta-analysis

    USGS Publications Warehouse

    Graly, Joseph A.; Bierman, Paul R.; Reusser, Lucas J.; Pavich, Milan J.

    2010-01-01

    In order to assess current understanding of meteoric 10Be dynamics and distribution in terrestrial soils, we assembled a database of all published meteoric 10Be soil depth profiles, including 104 profiles from 27 studies in globally diverse locations, collectively containing 679 individual measurements. This allows for the systematic comparison of meteoric 10Be concentration to other soil characteristics and the comparison of profile depth distributions between geologic settings. Percent clay, 9Be, and dithionite-citrate extracted Al positively correlate to meteoric 10Be in more than half of the soils where they were measured, but the lack of significant correlation in other soils suggests that no one soil factor controls meteoric 10Be distribution with depth. Dithionite-citrate extracted Fe and cation exchange capacity are only weakly correlated to meteoric 10Be. Percent organic carbon and pH are not significantly related to meteoric 10Be concentration when all data are complied.The compilation shows that meteoric 10Be concentration is seldom uniform with depth in a soil profile. In young or rapidly eroding soils, maximum meteoric 10Be concentrations are typically found in the uppermost 20 cm. In older, more slowly eroding soils, the highest meteoric 10Be concentrations are found at depth, usually between 50 and 200 cm. We find that the highest measured meteoric 10Be concentration in a soil profile is an important metric, as both the value and the depth of the maximum meteoric 10Be concentration correlate with the total measured meteoric 10Be inventory of the soil profile.In order to refine the use of meteoric 10Be as an estimator of soil erosion rate, we compare near-surface meteoric 10Be concentrations to total meteoric 10Be soil inventories. These trends are used to calibrate models of meteoric 10Be loss by soil erosion. Erosion rates calculated using this method vary based on the assumed depth and timing of erosional events and on the reference data selected.

  6. Correlation of objectively measured light exposure and serum vitamin D in men aged over 60 years.

    PubMed

    Fields, Alison J; Linnville, Steven E; Hoyt, Robert E

    2016-01-01

    Diminished vitamin D is common among older individuals. Sunlight contributes more to vitamin D synthesis than diet or supplementation. This study examined associations between objectively measured light exposure, vitamin D serum levels, and bone biomarkers in 100 men aged over 60 years. Light exposure was measured in lux via Actigraph monitors for 1 week. Significantly, greater levels of vitamin D were observed in participants with higher light exposure. Seasonal differences in lux were also noted. Significant differences in bone markers were not found. Objective measurement of light exposure is an inexpensive, simple, and effective way to address vitamin D deficiency.

  7. 10Be in late deglacial climate simulated by ECHAM5-HAM - Part 2: Isolating the solar signal from 10Be deposition

    NASA Astrophysics Data System (ADS)

    Heikkilä, U.; Shi, X.; Phipps, S. J.; Smith, A. M.

    2014-04-01

    This study investigates the effect of deglacial climate on the deposition of the solar proxy 10Be globally, and at two specific locations, the GRIP site at Summit, Central Greenland, and the Law Dome site in coastal Antarctica. The deglacial climate is represented by three 30 year time slice simulations of 10 000 BP (years before present = 1950 CE), 11 000 and 12 000 BP, compared with a preindustrial control simulation. The model used is the ECHAM5-HAM atmospheric aerosol-climate model, driven with sea-surface temperatures and sea ice cover simulated using the CSIRO Mk3L coupled climate system model. The focus is on isolating the 10Be production signal, driven by solar variability, from the weather- or climate-driven noise in the 10Be deposition flux during different stages of climate. The production signal varies at lower frequencies, dominated by the 11 year solar cycle within the 30 year timescale of these experiments. The climatic noise is of higher frequencies than 11 years during the 30 year period studied. We first apply empirical orthogonal function (EOF) analysis to global 10Be deposition on the annual scale and find that the first principal component, consisting of the spatial pattern of mean 10Be deposition and the temporally varying solar signal, explains 64% of the variability. The following principal components are closely related to those of precipitation. Then, we apply ensemble empirical decomposition (EEMD) analysis to the time series of 10Be deposition at GRIP and at Law Dome, which is an effective method for adaptively decomposing the time series into different frequency components. The low-frequency components and the long-term trend represent production and have reduced noise compared to the entire frequency spectrum of the deposition. The high-frequency components represent climate-driven noise related to the seasonal cycle of e.g. precipitation and are closely connected to high frequencies of precipitation. These results firstly show that

  8. 10Be in late deglacial climate simulated by ECHAM5-HAM - Part 2: Isolating the solar signal from 10Be deposition

    NASA Astrophysics Data System (ADS)

    Heikkilä, U.; Shi, X.; Phipps, S. J.; Smith, A. M.

    2013-10-01

    This study investigates the effect of deglacial climate on the deposition of the solar proxy 10Be globally, and at two specific locations, the GRIP site at Summit, Central Greenland, and the Law Dome site in coastal Antarctica. The deglacial climate is represented by three 30 yr time slice simulations of 10 000 BP (years before present = 1950 CE), 11 000 BP and 12 000 BP, compared with a preindustrial control simulation. The model used is the ECHAM5-HAM atmospheric aerosol-climate model, driven with sea surface temperatures and sea ice cover simulated using the CSIRO Mk3L coupled climate system model. The focus is on isolating the 10Be production signal, driven by solar variability, from the weather or climate driven noise in the 10Be deposition flux during different stages of climate. The production signal varies on lower frequencies, dominated by the 11yr solar cycle within the 30 yr time scale of these experiments. The climatic noise is of higher frequencies. We first apply empirical orthogonal functions (EOF) analysis to global 10Be deposition on the annual scale and find that the first principal component, consisting of the spatial pattern of mean 10Be deposition and the temporally varying solar signal, explains 64% of the variability. The following principal components are closely related to those of precipitation. Then, we apply ensemble empirical decomposition (EEMD) analysis on the time series of 10Be deposition at GRIP and at Law Dome, which is an effective method for adaptively decomposing the time series into different frequency components. The low frequency components and the long term trend represent production and have reduced noise compared to the entire frequency spectrum of the deposition. The high frequency components represent climate driven noise related to the seasonal cycle of e.g. precipitation and are closely connected to high frequencies of precipitation. These results firstly show that the 10Be atmospheric production signal is preserved

  9. Exposure-Specific and Age-Specific Attack Rates for Ebola Virus Disease in Ebola-Affected Households, Sierra Leone

    PubMed Central

    Bower, Hilary; Johnson, Sembia; Bangura, Mohamed S.; Kamara, Alie Joshua; Kamara, Osman; Mansaray, Saidu H.; Sesay, Daniel; Turay, Cecilia; Checchi, Francesco

    2016-01-01

    Using histories of household members of Ebola virus disease (EVD) survivors in Sierra Leone, we calculated risk of EVD by age and exposure level, adjusting for confounding and clustering, and estimated relative risks. Of 937 household members in 94 households, 448 (48%) had had EVD. Highly correlated with exposure, EVD risk ranged from 83% for touching a corpse to 8% for minimal contact and varied by age group: 43% for children <2 years of age; 30% for those 5–14 years of age; and >60% for adults >30 years of age. Compared with risk for persons 20–29 years of age, exposure-adjusted relative risks were lower for those 5–9 (0.70), 10–14 (0.64), and 15–19 (0.71) years of age but not for children <2 (0.92) or 2–4 (0.97) years of age. Lower risk for 5–19-year-olds, after adjustment for exposure, suggests decreased susceptibility in this group. PMID:27144428

  10. Mercury Exposure in Healthy Korean Weaning-Age Infants: Association with Growth, Feeding and Fish Intake.

    PubMed

    Chang, Ju Young; Park, Jeong Su; Shin, Sue; Yang, Hye Ran; Moon, Jin Soo; Ko, Jae Sung

    2015-11-17

    Low-level mercury (Hg) exposure in infancy might be harmful to the physical growth as well as neurodevelopment of children. The aim of this study was to investigate postnatal Hg exposure and its relationship with anthropometry and dietary factors in late infancy. We recruited 252 healthy Korean infants between six and 24 months of age from an outpatient clinic during the 2009/2010 and 2013/2014 seasons. We measured the weight and height of the infants and collected dietary information using questionnaires. The Hg content of the hair and blood was assessed using inductively coupled plasma mass spectroscopy. The geometric mean Hg concentration in the hair and blood was 0.22 (95% confidence interval: 0.20-0.24) µg/g and 0.94 (n = 109, 95% confidence interval: 0.89-0.99) µg/L, respectively. The hair Hg concentration showed a good correlation with the blood Hg concentration (median hair-to-blood Hg ratio: 202.7, r = 0.462, p < 0.001) and was >1 µg/g in five infants. The hair Hg concentration showed significant correlations with weight gain after birth (Z-score of the weight for age-Z-score of the birthweight; r = -0.156, p = 0.015), the duration (months) of breastfeeding as the dominant method of feeding (r = 0.274, p < 0.001), and the duration of fish intake more than once per week (r = 0.138, p = 0.033). In an ordinal logistic regression analysis with categorical hair Hg content (quartiles), dietary factors, including breastfeeding as the dominant method of feeding in late infancy (cumulative odds ratio: 6.235, 95% confidence interval: 3.086-12.597, p < 0.001) and the monthly duration of fish intake more than once per week (cumulative odds ratio: 1.203, 95% confidence interval: 1.034-1.401; p = 0.017), were significantly associated with higher hair Hg content. Weight gain after birth was not, however, significantly associated with hair Hg content after adjustment for the duration of breastfeeding as the dominant method of feeding. Low-level Hg exposure through

  11. Cosmic-Ray-Exposure Ages of Diogenites and the Collisional History of the HED Parent Body or Bodies

    NASA Technical Reports Server (NTRS)

    Welten, K. C.; Lindner, L.; vanderBorg, K.; Loeken, T.; Scherer, P.; Schultz, L.

    1996-01-01

    Cosmic-ray-exposure ages of meteorites provide information on the collisional history of their parent bodies and the delivery mechanism of meteorites to Earth. The exposure-age distributions of ordinary chondrites show distinct patterns for H, L, and LL types, consistent with their origin on different parent bodies. The exposure-age distributions of howardites, eucrites. and diogenites (HEDS) show a common pattern with major peaks at 22 Ma and 38 Ma This provides additional evidence for a common origin of the HED meteorites, possibly 4 Vesta, although orbital dynamics calculations showed that the delivery of meteorites from Vesta to Earth is difficult. However, the discovery of several kilometer-sized Vesta-like asteroids in the region between Vesta and the 3:1 resonance suggested that these seem more likely parent bodies of the HEDs than Vesta itself. This implies that the exposure-age clusters may represent samples of several parent bodies. Therefore, the near-absence of diogenites with ages <20 Ma might be of interest for the composition of these kilometer-sized fragments of Vesta. Here we present cosmic-ray-exposure ages of 20 diogenites, including 9 new meteorites. In addition, we calculate the probability for each peak to occur by chance, assuming a constant production rate of HED fragments.

  12. Natural ageing process accelerates the release of Ag from functional textile in various exposure scenarios

    NASA Astrophysics Data System (ADS)

    Ding, Dahu; Chen, Lulu; Dong, Shaowei; Cai, Hao; Chen, Jifei; Jiang, Canlan; Cai, Tianming

    2016-11-01

    Natural ageing process occurs throughout the life cycle of textile products, which may possess influences on the release behavior of additives such as silver nanoparticles (Ag NPs). In this study, we assessed the releasability of Ag NPs from a Ag NPs functionalized textile in five different exposure scenarios (i.e. tap water (TW), pond water (PW), rain water (RW), artificial sweat (AS), and detergent solution (DS) along with deionized water (DW) as reference), which were very likely to occur throughout the life cycle of the textile. For the pristine textile, although the most remarkable release was found in DW (6–15 μg Ag/g textile), the highest release rate was found in RW (around 7 μg Ag/(g textile·h)). After ageing treatment, the total released Ag could be increased by 75.7~386.0% in DW, AS and DS. Morphological analysis clearly showed that the Ag NPs were isolated from the surface of the textile fibre due to the ageing treatment. This study provides useful information for risk assessment of nano-enhanced textile products.

  13. Characteristics of H2S emission from aged refuse after excavation exposure.

    PubMed

    Shen, Dong-Sheng; Du, Yao; Fang, Yuan; Hu, Li-Fang; Fang, Cheng-Ran; Long, Yu-Yang

    2015-05-01

    Hydrogen sulfide (H2S(g)) emission from landfills is a widespread problem, especially when aged refuse is excavated. H2S(g) emission from aged refuse exposed to air was investigated and the results showed that large amounts of H2S(g) can be released, especially in the first few hours after excavation, when H2S(g) concentrations in air near refuse could reach 2.00 mg m(-3). Initial exposure to air did not inhibit the emission of H2S(g), as is generally assumed, but actually promoted it. The amounts of H2S(g) emitted in the first 2 d after excavation can be very dangerous, and the risks associated with the emission of H2S(g) could decrease significantly with time. Unlike a large number of sulfide existed under anaerobic conditions, the sulfide in aged municipal solid waste can be oxidized chemically to elemental sulfur (but not sulfate) under aerobic conditions, and its conversion rate was higher than 80%. Only microorganisms can oxidize the reduced sulfur species to sulfate, and the conversion rate could reach about 50%. Using appropriate techniques to enhance these chemical and biological transformations could allow the potential health risks caused by H2S(g) after refuse excavation to be largely avoided.

  14. Natural ageing process accelerates the release of Ag from functional textile in various exposure scenarios

    PubMed Central

    Ding, Dahu; Chen, Lulu; Dong, Shaowei; Cai, Hao; Chen, Jifei; Jiang, Canlan; Cai, Tianming

    2016-01-01

    Natural ageing process occurs throughout the life cycle of textile products, which may possess influences on the release behavior of additives such as silver nanoparticles (Ag NPs). In this study, we assessed the releasability of Ag NPs from a Ag NPs functionalized textile in five different exposure scenarios (i.e. tap water (TW), pond water (PW), rain water (RW), artificial sweat (AS), and detergent solution (DS) along with deionized water (DW) as reference), which were very likely to occur throughout the life cycle of the textile. For the pristine textile, although the most remarkable release was found in DW (6–15 μg Ag/g textile), the highest release rate was found in RW (around 7 μg Ag/(g textile·h)). After ageing treatment, the total released Ag could be increased by 75.7~386.0% in DW, AS and DS. Morphological analysis clearly showed that the Ag NPs were isolated from the surface of the textile fibre due to the ageing treatment. This study provides useful information for risk assessment of nano-enhanced textile products. PMID:27869136

  15. Natural ageing process accelerates the release of Ag from functional textile in various exposure scenarios.

    PubMed

    Ding, Dahu; Chen, Lulu; Dong, Shaowei; Cai, Hao; Chen, Jifei; Jiang, Canlan; Cai, Tianming

    2016-11-21

    Natural ageing process occurs throughout the life cycle of textile products, which may possess influences on the release behavior of additives such as silver nanoparticles (Ag NPs). In this study, we assessed the releasability of Ag NPs from a Ag NPs functionalized textile in five different exposure scenarios (i.e. tap water (TW), pond water (PW), rain water (RW), artificial sweat (AS), and detergent solution (DS) along with deionized water (DW) as reference), which were very likely to occur throughout the life cycle of the textile. For the pristine textile, although the most remarkable release was found in DW (6-15 μg Ag/g textile), the highest release rate was found in RW (around 7 μg Ag/(g textile·h)). After ageing treatment, the total released Ag could be increased by 75.7~386.0% in DW, AS and DS. Morphological analysis clearly showed that the Ag NPs were isolated from the surface of the textile fibre due to the ageing treatment. This study provides useful information for risk assessment of nano-enhanced textile products.

  16. Biomarkers of oxidative stress and inflammation after wood smoke exposure in a reconstructed Viking Age house.

    PubMed

    Jensen, Annie; Karottki, Dorina Gabriela; Christensen, Jannie Marie; Bønløkke, Jakob Hjort; Sigsgaard, Torben; Glasius, Marianne; Loft, Steffen; Møller, Peter

    2014-10-01

    Exposure to particles from combustion of wood is associated with respiratory symptoms, whereas there is limited knowledge about systemic effects. We investigated effects on systemic inflammation, oxidative stress and DNA damage in humans who lived in a reconstructed Viking Age house, with indoor combustion of wood for heating and cooking. The subjects were exposed to high indoor concentrations of PM2.5 (700-3,600 µg/m(3)), CO (10.7-15.3 ppm) and NO2 (140-154 µg/m(3)) during a 1-week stay. Nevertheless, there were unaltered levels of genotoxicity, determined as DNA strand breaks and formamidopyrimidine DNA glycosylase and oxoguanine DNA glycosylase 1 sensitive sites in peripheral blood mononuclear cells. There were also unaltered expression levels of OGG1, HMOX1, CCL2, IL8, and TNF levels in leukocytes. In serum, there were unaltered levels of C-reactive protein, IL6, IL8, TNF, lactate dehydrogenase, cholesterol, triglycerides, and high-density lipoproteins. The wood smoke exposure was associated with decreased serum levels of sICAM-1, and a tendency to decreased sVCAM-1 levels. There was a minor increase in the levels of circulating monocytes expressing CD31, whereas there were unaltered expression levels of CD11b, CD49d, and CD62L on monocytes after the stay in the house. In conclusion, even a high inhalation exposure to wood smoke was associated with limited systemic effects on markers of oxidative stress, DNA damage, inflammation, and monocyte activation.

  17. Lithologies Making Up CM Carbonaceous Chondrites and Their Link to Space Exposure Ages

    NASA Technical Reports Server (NTRS)

    Gregory, Timothy; Zolensky, Michael E.; Trieman, Alan; Berger, Eve; Le, Loan; Fagan, Amy; Takenouchi, Atsushi; Velbel, Michael A.; Nishiizumi, Kunihiko

    2015-01-01

    Chondrite parent bodies are among the first large bodies to have formed in the early Solar System, and have since remained almost chemically unchanged having not grown large enough or quickly enough to undergo differentiation. Their major nonvolatile elements bear a close resemblance to the solar photosphere. Previous work has concluded that CM chondrites fall into at least four distinct space exposure age groups (0.1 Ma, 0.2 Ma, 0.6 Ma and >2.0 Ma), but the meaning of these groupings is unclear. It is possible that these meteorites came from different parent bodies which broke up at different times, or instead came from the same parent body which underwent multiple break-up events, or a combination of these scenarios.

  18. Lithologies Making Up CM Carbonaceous Chondrites and Their Link to Space Exposure Ages

    NASA Technical Reports Server (NTRS)

    Gregory, Timothy; Zolensky, Michael E.; Trieman, Alan; Berger, Eve; Le, Loan; Fagan, Amy; Takenouchi, Atsushi; Velbel, Michael A.; Nishiizumi, Kuni

    2015-01-01

    Chondrite parent bodies are among the first large bodies to have formed in the early Solar System, and have since remained almost chemically unchanged having not grown large enough or quickly enough to undergo differentiation. Their major nonvolatile elements bear a close resemblance to the solar photosphere. Previous work has concluded that CM chondrites fall into at least four distinct space exposure age groups (0.1 megaannus, 0.2 megaannus, 0.6 megaannus and 2.0 megaannus), but the meaning of these groupings is unclear. It is possible that these meteorites came from different parent bodies which broke up at different times, or instead came from the same parent body which underwent multiple break-up events, or a combination of these scenarios.

  19. Early-age heat exposure affects skeletal muscle satellite cell proliferation and differentiation in chicks.

    PubMed

    Halevy, O; Krispin, A; Leshem, Y; McMurtry, J P; Yahav, S

    2001-07-01

    Exposure of young chicks to thermal conditioning (TC; i.e., 37 degrees C for 24 h) resulted in significantly improved body and muscle growth at a later age. We hypothesized that TC causes an increase in satellite cell proliferation, necessary for further muscle hypertrophy. An immediate increase was observed in satellite cell DNA synthesis in culture and in vivo in response to TC of 3-day-old chicks to levels that were significantly higher than those of control chicks. This was accompanied by a marked induction of insulin-like growth factor-I (IFG-I), but not hepatocyte growth factor in the breast muscle. No significant difference between treatments in plasma IGF-I levels was observed. A marked elevation in muscle regulatory factors on day 5, followed by a decline in cell proliferation on day 6 together with continuous high levels of IGF-I in the TC chick muscle may indicate accelerated cell differentiation. These data suggest a central role for IGF-I in the immediate stimulation of satellite cell myogenic processes in response to heat exposure.

  20. PM2.5 Exposure Suppresses Dendritic Maturation in Subgranular Zone in Aged Rats.

    PubMed

    Cheng, Lewis; Lau, Way K W; Fung, Timothy K H; Lau, Benson W M; Chau, Bolton K H; Liang, Yutong; Wang, Zhe; So, Kwok Fai; Wang, Tao; Chan, Chetwyn C H; Lee, Tatia M C

    2017-03-08

    Detrimental effects of long-term inhalation of fine particulate matter (PM2.5) on the pulmonary and cardiovascular systems have been widely reported. Recent studies have shown that exposure to PM2.5 also causes adverse neurocognitive effects. This study investigates the effects of inhaled ammonium sulfate, which is a major compound of inorganic air pollutants in PM2.5, on adult neurogenesis in aged Sprague-Dawley rats. A total of 20 rats were randomly assigned to experimental (n = 10) and control (n = 10) conditions, wherein they were exposed to either ammonium sulfate or sham air for 2 h per day and for 28 consecutive days. It was observed that ammonium sulfate inhibited the maturation process and diminished dendritic complexity of immature neurons in the subgranular zone (SGZ) of the hippocampus significantly, although the number of neural stem cells or the rates of differentiation were comparable between the two groups. Our findings provide clear evidence on the direct relationship between air quality and advantageous neurogenesis. Exposure to PM leads to specific adverse effects on the maturation process during neurogenesis.

  1. Cosmogenic He-3 exposure ages of basalts from Ascension Island - implications for evolution of ocean islands

    NASA Astrophysics Data System (ADS)

    Ammon, K.; Dunai, T. J.; Stuart, F. M.; Meriaux, A.-S.; Gayer, E.

    2009-04-01

    Ascension Island is the emergent top of a volcano situated at 7°56'S and 14°22'W in the South Atlantic Ocean, approximately 90 km west of the Mid-Atlantic Ridge and 50 km south of the Ascension Fracture Zone [1, 2]. It rises about 860 m above sea level and the base of the volcano covers about 2000 km2 approximately 3200 m beneath sea level [3]. Volcanic activity is associated with the Mid-Atlantic Ridge, and commenced at 6-7 Ma [2, 4, 5]. The volcanic rocks of Ascension Island are transitional to mildly-alkaline basalt to rhyolite volcanic suite and are distinguished by trace element ratios (e.g. Zr/Nb) [3]. Whereas the age of the trachyte intrusions are well constrained (0.6 - 1.0 Ma) [e.g. 3] the younger basalt suites have not been dated reliably and the low K concentration make Ar/Ar dating difficult. In order to reconstruct the volcanic history of Ascension Island we have used cosmogenic He-3 in olivine and pyroxene phenocrysts from uneroded basalt flows to date the three basalt lava suites that appear to span the range of volcanism. Ages of co-genetic pyroxene and olivine agree within analytical uncertainties. Implanted radiogenic He-4 tends to lower He-3 derived exposure ages therefore some olivine samples were etched with HF/HNO3 to remove about 30% of the sample mass. The so etched olivine is systematically older (by less than 10%) than the unetched samples. The three basalt suites have exposure ages of 300 to 190 ka. The high and intermediate Zr/Nb basalts seem to have been erupted contemporaneously or at least in overlapping events about 300 ka ago. These suites were previously thought to be separated in time on the basis of K-Ar chronology and stratigraphy [3]. The third suite which seams to be a more local vent is erupted between 260 and 190 ka. Our new data indicate the co-existence of different magma chambers with different geochemical signatures. [1] E. Bourdon, C. Hemond, Mineralogy and Petrology 71(2001) 127-138. [2] D.L. Nielson, B.S. Sibbett

  2. Prenatal polybrominated diphenyl ether and perfluoroalkyl substance exposures and executive function in school-age children.

    PubMed

    Vuong, Ann M; Yolton, Kimberly; Webster, Glenys M; Sjödin, Andreas; Calafat, Antonia M; Braun, Joseph M; Dietrich, Kim N; Lanphear, Bruce P; Chen, Aimin

    2016-05-01

    Executive function is a critical behavioral trait rarely studied in relation to potential neurotoxicants. Prenatal exposure to polybrominated diphenyl ethers (PBDEs) and perfluoroalkyl substances (PFASs) has been associated with adverse neurodevelopment, but there is limited research on executive function. Data from 256 mother-child pairs in the Health Outcomes and Measures of the Environment Study, a prospective birth cohort (2003-2006, Cincinnati, OH), was used to examine maternal serum PBDEs and PFASs and executive function in children ages 5 and 8 years. Maternal serum PBDEs and PFASs were measured at 16±3 weeks gestation. Executive function was assessed with the parent-rated Behavior Rating Inventory of Executive Function (BRIEF), which yields composite measures: behavioral regulation index, metacognition index, and global executive composite. Higher BRIEF scores indicate executive function impairments. Linear mixed models and generalized estimating equations were used to estimate covariate-adjusted associations between PBDEs and PFASs and executive function. A 10-fold increase in BDE-153 was associated with poorer behavior regulation (β=3.23, 95% CI 0.60, 5.86). Higher odds of having a score ≥60 in behavior regulation (OR=3.92, 95% CI 1.76, 8.73) or global executive functioning (OR=2.34, 95% CI 1.05, 5.23) was observed with increased BDE-153. Each ln-unit increase in perfluorooctane sulfonate (PFOS) was associated with poorer behavior regulation (β=3.14, 95% CI 0.68, 5.61), metacognition (β=3.10, 95% CI 0.62, 5.58), and global executive functioning (β=3.38, 95% CI 0.86, 5.90). However, no association was observed between perfluorooctanoate (PFOA) and executive function. Prenatal exposures to BDE-153 and PFOS may be associated with executive function deficits in school-age children.

  3. Cumulative Lead Exposure and Tooth Loss in Men: The Normative Aging Study

    PubMed Central

    Arora, Manish; Weuve, Jennifer; Weisskopf, Marc G.; Sparrow, David; Nie, Huiling; Garcia, Raul I.; Hu, Howard

    2009-01-01

    Background Individuals previously exposed to lead remain at risk because of endogenous release of lead stored in their skeletal compartments. However, it is not known if long-term cumulative lead exposure is a risk factor for tooth loss. Objectives We examined the association of bone lead concentrations with loss of natural teeth. Methods We examined 333 men enrolled in the Veterans Affairs Normative Aging Study. We used a validated K-shell X-ray fluorescence (KXRF) method to measure lead concentrations in the tibial midshaft and patella. A dentist recorded the number of teeth remaining, and tooth loss was categorized as 0, 1–8 or ≥ 9 missing teeth. We used proportional odds models to estimate the association of bone lead biomarkers with tooth loss, adjusting for age, smoking, diabetes, and other putative confounders. Results Participants with ≥ 9 missing teeth had significantly higher bone lead concentrations than those who had not experienced tooth loss. In multivariable-adjusted analyses, men in the highest tertile of tibia lead (> 23 μg/g) and patella lead (> 36 μg/g) had approximately three times the odds of having experienced an elevated degree of tooth loss (≥ 9 vs. 0–8 missing teeth or ≥ 1 vs. 0 missing teeth) as those in the lowest tertile [prevalence odds ratio (OR) = 3.03; 95% confidence interval (CI), 1.60–5.76 and OR = 2.41; 95% CI, 1.30–4.49, respectively]. Associations between bone lead biomarkers and tooth loss were similar in magnitude to the increased odds observed in participants who were current smokers. Conclusion Long-term cumulative lead exposure is associated with increased odds of tooth loss. PMID:20019902

  4. Prenatal marijuana exposure: effect on child depressive symptoms at ten years of age.

    PubMed

    Gray, Kimberly A; Day, Nancy L; Leech, Sharon; Richardson, Gale A

    2005-01-01

    Studies of the consequences of prenatal marijuana use have reported effects predominantly on the behavioral and cognitive development of the children. Research on other aspects of child neurobehavioral development, such as psychiatric symptomatology, has been limited. This study examines the relations between prenatal marijuana exposure (PME) and child depressive symptoms at 10 years of age. Data are from the 10-year follow-up of 633 mother-child dyads who participated in the Maternal Health Practices and Child Development Project. Maternal prenatal and current substance use, measures of the home environment, demographic status, and psychosocial characteristics were ascertained at prenatal months four and seven, at delivery, and at age 10. At age 10, the children also completed the Children's Depression Inventory (CDI) [M. Kovacs. The Children's Depression Inventory, Multi-Health Systems, Inc., North Tonawanda, NY, (1992).], a self-report measure of current depressive symptoms. Multivariate regressions were used to test trimester-specific effects of marijuana and their associations with the CDI total score, while controlling for significant prenatal predictors and significant current covariates of childhood depression. PME in the first and third trimesters predicted significantly increased levels of depressive symptoms. This finding remained significant after controlling for all identified covariates from both the prenatal period and the current phase at age 10. These findings reflect an association with the level of depressive symptoms rather than a diagnosis of a major depressive disorder. Other significant correlates of depressive symptoms in the children included maternal education, maternal tobacco use (prenatal or current), and the child's composite IQ score. These findings are consistent with recent reports that identify specific areas of the brain and specific brain functions that are associated with PME.

  5. Secondhand tobacco smoke exposure differentially alters nucleus tractus solitarius neurons at two different ages in developing non-human primates

    SciTech Connect

    Sekizawa, Shin-ichi; Joad, Jesse P.; Pinkerton, Kent E.; Bonham, Ann C.

    2010-01-15

    Exposing children to secondhand tobacco smoke (SHS) is associated with increased risk for asthma, bronchiolitis and SIDS. The role for changes in the developing CNS contributing to these problems has not been fully explored. We used rhesus macaques to test the hypothesis that SHS exposure during development triggers neuroplastic changes in the nucleus tractus solitarius (NTS), where lung sensory information related to changes in airway and lung function is first integrated. Pregnant monkeys were exposed to filtered air (FA) or SHS for 6 h/day, 5 days/week starting at 50-day gestational age. Mother/infant pairs continued the exposures postnatally to age 3 or 13 months, which may be equivalent to approximately 1 or 4 years of human age, respectively. Whole-cell recordings were made of second-order NTS neurons in transverse brainstem slices. To target the consequences of SHS exposure based on neuronal subgroups, we classified NTS neurons into two phenotypes, rapid-onset spiking (RS) and delayed-onset spiking (DS), and then evaluated intrinsic and synaptic excitabilities in FA-exposed animals. RS neurons showed greater cell excitability especially at age of 3 months while DS neurons received greater amplitudes of excitatory postsynaptic currents (EPSCs). Developmental neuroplasticity such as increases in intrinsic and synaptic excitabilities were detected especially in DS neurons. In 3 month olds, SHS exposure effects were limited to excitatory changes in RS neurons, specifically increases in evoked EPSC amplitudes and increased spiking responses accompanied by shortened action potential width. By 13 months, the continued SHS exposure inhibited DS neuronal activity; decreases in evoked EPSC amplitudes and blunted spiking responses accompanied by prolonged action potential width. The influence of SHS exposure on age-related and phenotype specific changes may be associated with age-specific respiratory problems, for which SHS exposure can increase the risk, such as SIDS

  6. Shortening rates across the foothills of the Western Kunlun (Xinjiang, China) inferred from geomorphic measurements and cosmogenic 10Be dating.

    NASA Astrophysics Data System (ADS)

    Coudroy, T.; van der Woerd, J.; Li, H.; Barrier, L.; Tapponnier, P.; Simoes, M.; Thuizat, R.; Pan, J.; Si, J.; Xu, T.

    2009-04-01

    The Western Kunlun, which bounds north-western Tibetan Plateau, is one of the largest mountain range of Asia, with altitudes peaking at 6500-7500 m asl, and crustal thicknesses of up to ~70 km. North of the plateau, in the foreland of the range, an active fold-and-thrust belt extends 200 km into the Tarim basin, but remains poorly documented regarding amounts of shortening or deformation rates. We discuss the distribution of deformation on the basis of a study of specific foreland folds and faults using high resolution satellite imagery, digital elevation models, seismic reflection data, on-site topographic measurements and cosmogenic isotope dating. South of Hotan city, the 250 km-long Tekelike Fault - the mountain-front thrust that dips beneath the 45 km-wide, 5400m-high Tekelike Range, a basement ramp-anticline - cuts and offsets terraces abandoned by the Karakash River. 10Be concentrations of surface and sub-surface samples from these terraces upper-most deposits yield an exposure age of about 100 kyr for the upper terrace that lies 140 m above the present river bed, implying an incision rate of 1.4 mm/yr. Assuming a dip of 45 +/-15° and neglecting changes in river dynamics over this time period, this age would imply a minimum, average shortening rate of 1.4 +/- 0.7 mm/yr across the thrust. Farther North, 100 to 200 km-long WNW-ESE trending anticlines deform the thick Tertiary and Quaternary sedimentary series lying in the foreland of the range. The 150 km-long, 35 km-wide Yecheng-Pishan anticline folds Plio-Quaternary molasses. Drainages crossing this growing anticline have abandoned flights of inset terraces on the sides of wind-gaps. The maximum elevation of the highest terrace above local drainage is about 350m. Near Pishan city, flat, well-preserved terrace surfaces are covered by thin loess, in turn capped by loose gravel pavement. On the uppermost two terraces of this valley, 70 and 120 meters-high, cosmogenic 10Be concentrations in surface and sub

  7. An improved north-south synchronization of ice core records around the 41 kyr 10Be peak

    NASA Astrophysics Data System (ADS)

    Raisbeck, Grant M.; Cauquoin, Alexandre; Jouzel, Jean; Landais, Amaelle; Petit, Jean-Robert; Lipenkov, Vladimir Y.; Beer, Juerg; Synal, Hans-Arno; Oerter, Hans; Johnsen, Sigfus J.; Steffensen, Jorgen P.; Svensson, Anders; Yiou, Françoise

    2017-03-01

    Using new high-resolution 10Be measurements in the NGRIP, EDML and Vostok ice cores, together with previously published data from EDC, we present an improved synchronization between Greenland and Antarctic ice cores during the Laschamp geomagnetic excursion ˜ 41 kyr ago. We estimate the precision of this synchronization to be ±20 years, an order of magnitude better than previous work. We discuss the implications of this new synchronization for making improved estimates of the depth difference between ice and enclosed gas of the same age (Δdepth), difference between age of ice and enclosed gas at the same depth (Δage) in the EDC and EDML ice cores, spectral properties of the 10Be profiles and phasing between Dansgaard-Oeschger-10 (in NGRIP) and AIM-10 (in EDML and EDC).

  8. SOLAR WIND IMPLANTATION MODEL FOR {sup 10}Be IN CALCIUM-ALUMINUM INCLUSIONS

    SciTech Connect

    Bricker, Glynn E.; Caffee, Marc W. E-mail: mcaffee@purdue.ed

    2010-12-10

    We propose a model for the incorporation of {sup 10}Be within calcium-aluminum inclusions (CAIs) in primitive carbonaceous meteorites. In this model, {sup 10}Be is produced by energetic particle reactions in the proto-solar atmosphere of a more active proto-Sun characterized by energetic particle fluxes higher than contemporary particle fluxes. This {sup 10}Be is incorporated into the solar wind that is then implanted into CAI precursor material. This production mechanism is operational in the contemporary solar system implanting {sup 10}Be in lunar materials. The contemporary production rate of {sup 10}Be at the surface of the Sun is {approx}0.1 {sup 10}Be cm{sup -2} s{sup -1}. Scaling up the contemporary {sup 10}Be production in the proto-Sun by a factor of 10{sup 5} would increase the production rate to 10{sup 410}Be cm{sup -2} s{sup -1}. Using this enhanced production value in conjunction with refractory mass inflow rates at 0.06 AU from the proto-Sun we model {sup 10}Be concentrations in CAI precursors. We calculate the content of solar-wind-implanted {sup 10}Be would have been of the order of 10{sup 1210}Be g{sup -1} in CAIs, consistent with initial{sup 10}Be content found from boron-beryllium isotopic systematics in CAIs.

  9. Mercury Exposure in Healthy Korean Weaning-Age Infants: Association with Growth, Feeding and Fish Intake

    PubMed Central

    Chang, Ju Young; Park, Jeong Su; Shin, Sue; Yang, Hye Ran; Moon, Jin Soo; Ko, Jae Sung

    2015-01-01

    Low-level mercury (Hg) exposure in infancy might be harmful to the physical growth as well as neurodevelopment of children. The aim of this study was to investigate postnatal Hg exposure and its relationship with anthropometry and dietary factors in late infancy. We recruited 252 healthy Korean infants between six and 24 months of age from an outpatient clinic during the 2009/2010 and 2013/2014 seasons. We measured the weight and height of the infants and collected dietary information using questionnaires. The Hg content of the hair and blood was assessed using inductively coupled plasma mass spectroscopy. The geometric mean Hg concentration in the hair and blood was 0.22 (95% confidence interval: 0.20–0.24) µg/g and 0.94 (n = 109, 95% confidence interval: 0.89–0.99) µg/L, respectively. The hair Hg concentration showed a good correlation with the blood Hg concentration (median hair-to-blood Hg ratio: 202.7, r = 0.462, p < 0.001) and was >1 µg/g in five infants. The hair Hg concentration showed significant correlations with weight gain after birth (Z-score of the weight for age—Z-score of the birthweight; r = −0.156, p = 0.015), the duration (months) of breastfeeding as the dominant method of feeding (r = 0.274, p < 0.001), and the duration of fish intake more than once per week (r = 0.138, p = 0.033). In an ordinal logistic regression analysis with categorical hair Hg content (quartiles), dietary factors, including breastfeeding as the dominant method of feeding in late infancy (cumulative odds ratio: 6.235, 95% confidence interval: 3.086–12.597, p < 0.001) and the monthly duration of fish intake more than once per week (cumulative odds ratio: 1.203, 95% confidence interval: 1.034–1.401; p = 0.017), were significantly associated with higher hair Hg content. Weight gain after birth was not, however, significantly associated with hair Hg content after adjustment for the duration of breastfeeding as the dominant method of feeding. Low-level Hg exposure

  10. Determination, by 10Be Cosmogenic Dating, of Slip-rates on the Karakorum Fault (Tibet) and Paleoclimatic Evolution Since 200 ka

    NASA Astrophysics Data System (ADS)

    Chevalier, M.; Tapponnier, P.; van der Woerd, J.; Finkel, R. C.; Ryerson, F. J.; Li, H.; Liu, Q.

    2006-12-01

    The millennial slip-rate along the Karakorum Fault, main right-lateral strike-slip fault north of the Himalayas, and its role in the kinematics of the present-day deformation of Tibet, are debated. Recent InSAR data suggest that it is barely active (1 ± 3 mm/yr). Surface exposure dating (10Be) of 266 quartz-rich samples collected on 8 lateral moraines crests and on 6 fans or terraces south of Bangong Lake in Western Tibet indicate instead that it slips at least five, and more likely ten times as fast. The geomorphic features we studied are offset by the fault by amounts that range between ~9 and ~1500 m. Offsets were measured both in the field and from retro-deformation of high-resolution satellite images (Ikonos, Corona, Spot and Landsat 7). Multiple samples (10 on average) were collected from each surface to assess exposure age variability and dispersion. From the Indus bend at Chaxikang to Mount Kailas, the slip-rate values obtained with different inferences vary from >11.8 ± 4.7 mm/yr to >14.3 ± 4.2 mm/yr. The cosmogenic exposure ages we obtain show good correlation with global climate changes in the last 200 000 years, as recorded by different climatic proxies (Specmap, Vostock, Marine Oxygen Isotopes, Guliya ice cap). The distribution of ages suggests for instance that the maximum glacial advances recorded by moraine emplacement occurred when the climate was coldest, during the LGM (~20 ka), the late MIS-3 (~40 ka), and MIS-6 (~140 ka). About 70% of moraine sample ages are younger than 50 ka with peaks during the LGM (15 to 30 ka, 45%) and the MIS-3 (35 to 50 ka, 28%). The view that the LGM advance was a minor event in the Western Himalayas may thus only reflect insufficient sampling. With few exceptions, most of the fans we dated have been emplaced during post-glacial warming and in the early Holocene. Such correlations imply that there is little bias in our cosmogenic exposure age measurements.

  11. On the Relationship between Cosmic Ray Exposure Ages and Petrography of CM Chondrites

    NASA Technical Reports Server (NTRS)

    Takenouchi, A.; Zolensky, M. E.; Nishiizumi, K.; Caffee, M.; Velbel, M. A.; Ross, K.; Zolensky, A.; Lee, L.; Imae, N.; Yamaguchi, A.; Mikouchi, T.

    2014-01-01

    Carbonaceous (C) chondrites are potentially the most primitive among chondrites because they mostly escaped thermal metamorphism that affected the other chondrite groups. C chondrites are chemically distinguished from other chondrites by their high Mg/Si ratios and refractory elements, and have experienced various degrees of aqueous alteration. They are subdivided into eight subgroups (CI, CM, CO, CV, CK, CR, CB and CH) based on major element and oxygen isotopic ratios. Their elemental ratios vary over a wide range, in contrast to those of ordinary and enstatite chondrites which are relatively uniform. It is critical to know how many separate bodies are represented by the C chondrites. In this study we defined 4 distinct cosmic-ray exposure (CRE) age groups of CMs and systematically characterized the petrography in each of the 4 CRE age groups to determine whether the groups have significant petrographic differences with such differences probably reflecting different parent body (asteroid) geological processing, or multiple original bodies. We have reported the results of a preliminary grouping at the NIPR Symp. in 2013 [3], however, we revised the grouping and here report our new results.

  12. A laboratory exposure system to study the effects of aging on super-micron aerosol particles

    SciTech Connect

    Santarpia, Joshua; Sanchez, Andres L.; Lucero, Gabriel Anthony; Servantes, Brandon Lee; Hubbard, Joshua Allen

    2014-02-01

    A laboratory system was constructed that allows the super-micron particles to be aged for long periods of time under conditions that can simulate a range of natural environments and conditions, including relative humidity, oxidizing chemicals, organics and simulated solar radiation. Two proof-of-concept experiments using a non-biological simulant for biological particles and a biological simulant demonstrate the utility of these types of aging experiments. Green Visolite®, which is often used as a tracer material for model validation experiments, does not degrade with exposure to simulated solar radiation, the actual biological material does. This would indicate that Visolite® should be a good tracer compound for mapping the extent of a biological release using fluorescence as an indicator, but that it should not be used to simulate the decay of a biological particle when exposed to sunlight. The decay in the fluorescence measured for B. thurengiensis is similar to what has been previously observed in outdoor environments.

  13. Prenatal Perfluoroalkyl Substance Exposure and Child Adiposity at 8 Years of Age: The HOME Study

    PubMed Central

    Braun, Joseph M.; Chen, Aimin; Romano, Megan E.; Calafat, Antonia M.; Webster, Glenys M.; Yolton, Kimberly; Lanphear, Bruce P.

    2015-01-01

    Objective To examine relationships between prenatal perfluoroalkyl substance (PFAS) exposure and adiposity in children born to women who lived downstream from a fluoropolymer manufacturing plant. Methods Data are from a prospective cohort in Cincinnati, OH (HOME Study). We measured perfluorooctanoic (PFOA), perfluorooctane sulfonic (PFOS), perfluorononanoic (PFNA), and perfluorohexane sulfonic (PFHxS) acids in prenatal serum samples. We estimated differences in body mass index z-scores (BMI), waist circumference, and body fat at 8 years of age (n=204) and BMI between 2–8 years of age (n=285) according to PFAS concentrations. Results Children born to women in the top two PFOA terciles had greater adiposity at 8 years than children in the 1st tercile. For example, waist circumference (cm) was higher among children in the 2nd (4.3; 95% CI:1.7, 6.9) and 3rd tercile (2.2; 95% CI:−0.5, 4.9) compared to children in the 1st tercile. Children in the top two PFOA terciles also had greater BMI gains from 2–8 years compared to children in the 1st tercile (p<0.05). PFOS, PFNA and PFHxS were not associated with adiposity. Conclusions In this cohort, higher prenatal serum PFOA concentrations were associated with greater adiposity at 8 years and a more rapid increase in BMI between 2–8 years. PMID:26554535

  14. A Numerical Model to Assess Soil Fluxes from Meteoric 10Be Data

    NASA Astrophysics Data System (ADS)

    Campforts, B.; Govers, G.; Vanacker, V.; Vanderborght, J.; Smolders, E.; Baken, S.

    2015-12-01

    Meteoric 10Be may be mobile in the soil system. The latter hampers a direct translation of meteoric 10Be inventories into spatial variations in erosion and deposition rates. Here, we present a spatially explicit 2D model that allows us to simulate the behaviour of meteoric 10Be in the soil system. The Be2D model is then used to analyse the potential impact of human-accelerated soil fluxes on meteoric 10Be inventories. The model consists of two parts. A first component deals with advective and diffusive mobility of meteoric 10Be within the soil profile including particle migration, chemical leaching and bioturbation, whereas a second component describes lateral soil (and meteoric 10Be) fluxes over the hillslope. Soil depth is calculated dynamically, accounting for soil production through weathering and lateral soil fluxes from creep, water and tillage erosion. Model simulations show that meteoric 10Be inventories can indeed be related to erosion and deposition, across a wide range of geomorphological and pedological settings. However, quantification of the effects of vertical mobility is essential for a correct interpretation of the observed spatial patterns in 10Be data. Moreover, our simulations suggest that meteoric 10Be can be used as a tracer to unravel human impact on soil fluxes when soils have a high retention capacity for meteoric meteoric 10Be. Application of the Be2D model to existing data sets shows that model parameters can reliably be constrained, resulting in a good agreement between simulated and observed meteoric 10Be concentrations and inventories. This confirms the suitability of the Be2D model as a robust tool to underpin quantitative interpretations of spatial variability in meteoric 10Be data for eroding landscapes.

  15. AMS measurement of 10Be concentrations in marine sediments from Chile Trench at the TANDAR laboratory

    NASA Astrophysics Data System (ADS)

    Rodrigues, D.; Arazi, A.; Fernández Niello, J. O.; Martí, G. V.; Negri, A. E.; Abriola, D.; Capurro, O. A.; Cardona, M. A.; de Barbará, E.; Gollan, F.; Hojman, D.; Pacheco, A. J.; Samsolo, N.; Togneri, M.; Villanueva, D.

    2017-03-01

    The 10Be/9Be ratios in marine sediments samples from the Southern Chile Trench have been measured using accelerator mass spectrometry (AMS). The samples were measured at the TANDAR accelerator, where the discrimination of the 10Be radionuclides was achieved by means of a passive absorber in front of an ionization chamber. This setup along with the high voltage available, provided a complete suppression of the 10B isobar interference. The obtained values for the 10Be concentrations, of the order of 109 atoms/g, are the first 10Be measurements from the Southern Chile Trench and offer an excellent tracer to quantitatively study the recycling of sediments in Andean magmas.

  16. Association Between a Single General Anesthesia Exposure Before Age 36 Months and Neurocognitive Outcomes in Later Childhood

    PubMed Central

    Sun, Lena S.; Li, Guohua; Miller, Tonya L. K.; Salorio, Cynthia; Byrne, Mary W.; Bellinger, David C.; Ing, Caleb; Park, Raymond; Radcliffe, Jerilynn; Hays, Stephen R.; DiMaggio, Charles J.; Cooper, Timothy J.; Rauh, Virginia; Maxwell, Lynne G.; Youn, Ahrim; McGowan, Francis X.

    2017-01-01

    IMPORTANCE Exposure of young animals to commonly used anesthetics causes neurotoxicity including impaired neurocognitive function and abnormal behavior. The potential neurocognitive and behavioral effects of anesthesia exposure in young children are thus important to understand. OBJECTIVE To examine if a single anesthesia exposure in otherwise healthy young children was associated with impaired neurocognitive development and abnormal behavior in later childhood. DESIGN, SETTING, AND PARTICIPANTS Sibling-matched cohort study conducted between May 2009 and April 2015 at 4 university-based US pediatric tertiary care hospitals. The study cohort included sibling pairs within 36 months in age and currently 8 to 15 years old. The exposed siblings were healthy at surgery/anesthesia. Neurocognitive and behavior outcomes were prospectively assessed with retrospectively documented anesthesia exposure data. EXPOSURES A single exposure to general anesthesia during inguinal hernia surgery in the exposed sibling and no anesthesia exposure in the unexposed sibling, before age 36 months. MAIN OUTCOMES AND MEASURES The primary outcome was global cognitive function (IQ). Secondary outcomes included domain-specific neurocognitive functions and behavior. A detailed neuropsychological battery assessed IQ and domain-specific neurocognitive functions. Parents completed validated, standardized reports of behavior. RESULTS Among the 105 sibling pairs, the exposed siblings (mean age, 17.3 months at surgery/anesthesia; 9.5% female) and the unexposed siblings (44% female) had IQ testing at mean ages of 10.6 and 10.9 years, respectively. All exposed children received inhaled anesthetic agents, and anesthesia duration ranged from 20 to 240 minutes, with a median duration of 80 minutes. Mean IQ scores between exposed siblings (scores: full scale = 111; performance = 108; verbal = 111) and unexposed siblings (scores: full scale = 111; performance = 107; verbal = 111) were not statistically

  17. The influence of worm age, duration of exposure and endpoint selection on bioassay sensitivity for Neanthes arenaceodentata (Annelida: Polychaeta)

    SciTech Connect

    Bridges, T.S.; Farrar, J.D.

    1997-08-01

    The influence of worm age, duration of exposure, and endpoint selection on bioassay sensitivity were evaluated for Neanthes arenaceodentata. Worms were exposed to contaminated sediment collected from Black Rock Harbor (BRH) near Bridgeport, Connecticut, USA. This sediment was diluted with clean control sediment to result in five experimental treatments: 0, 25, 50, 75, and 100% BRH. Three exposure scenarios were employed: (1) a 4-week exposure beginning with newly emerged juveniles (EJ-4w), (2) a 7-week exposure beginning with newly emerged juveniles (EJ-7w), and (3) a 4-week exposure beginning with 3-week-old juveniles (3WO-4w). Six measures of worm size were recorded at the conclusion of each exposure to evaluate differences among measurement endpoints. Survival was significantly reduced at the 25% BRH level for the EJ-7w scenario and at the 100% BRH level for the EJ-4w and 3WO-4w scenarios. Growth was significantly reduced at the 25% BRH level in each exposure scenario. Estimates based on the calculated minimum detectable difference indicated that considerably lower concentrations of BRH (6--10%) should be distinguishable by measuring effects on Neanthes growth. Worm size measured in terms of projected area, dry weight, and ash-free dry weight provided the most sensitive measures of effects. Increasing the length of exposure from 4 to 7 weeks and initiating exposures with emergent juveniles rather than 3-week-old worms increased the sensitivity of the bioassay. The results of this study demonstrate that N. arenacedentata is sensitive to the presence of sediment-associated contaminants and that test animal age, duration of exposure, and choice of endpoint can have a large effect on the magnitude of the toxic response observed.

  18. Dating Plio-Pleistocene glacial sediments using the cosmic-ray-produced radionuclides 10Be and 26Al

    USGS Publications Warehouse

    Balco, G.; Stone, J.O.H.; Jennings, C.

    2005-01-01

    We use the cosmic-ray-produced radionuclides 26Al and 10Be to date Plio-Pleistocene glacial sediment sequences. These two nuclides are produced in quartz at a fixed ratio, but have different decay constants. If a sample is exposed at the surface for a time and then buried by overburden and thus removed from the cosmic-ray flux, the 26Al/10Be ratio is related to the duration of burial. We first attempted to date pre-Wisconsinan tills by measuring 26Al and 10Be in fluvial sediments beneath them and applying the method of "burial dating," which previous authors have used to date river sediment carried into caves. This method, however, requires simplifying assumptions about the 26Al and 10Be concentrations in the sediment at the time of burial. We show that these assumptions are not valid for river sediment in glaciated regions. 26Al and 10Be analyses of such sediment do not provide accurate ages for these tills, although they do yield limiting ages in some cases. We overcome this difficulty by instead measuring 26Al and 10Be in quartz from paleosols that are buried by tills. We use a more general mathematical approach to determine the initial nuclide concentrations in the paleosol at the time it was buried, as well as the duration of burial. This technique provides a widely applicable improvement on other means of dating Plio-Pleistocene terrestrial glacial sediments, as well as a framework for applying cosmogenic-nuclide dating techniques in complicated stratigraphic settings. We apply it to pre-Wisconsinan glacial sediment sequences in southwest Minnesota and eastern South Dakota. Pre-Wisconsinan tills underlying the Minnesota River Valley were deposited 0.5 to 1.5 Ma, and tills beneath the Prairie Coteau in eastern South Dakota and adjacent Minnesota were deposited 1 to 2 Ma.

  19. Neurodevelopmental performance among school age children in rural Guatemala is associated with prenatal and postnatal exposure to carbon monoxide, a marker for exposure to woodsmoke.

    PubMed

    Dix-Cooper, Linda; Eskenazi, Brenda; Romero, Carolina; Balmes, John; Smith, Kirk R

    2012-03-01

    We investigated whether early life chronic exposure to woodsmoke, using personal passive 48-h carbon monoxide (CO) as an indicator, is associated with children's neurodevelopmental and behavioral performance. CO measures were collected every 3 months from 2002 to 2005 among mother-child dyads during the Randomized Exposure Study of Pollution Indoors and Respiratory Effects (RESPIRE) stove intervention trial in San Marcos, Guatemala. From March to June, 2010, study children of age 6-7 years, performed a follow-up non-verbal, culturally adapted neurodevelopmental assessment. We found inverse associations between CO exposure of pregnant mothers during their 3rd trimesters (m=3.8ppm ± 3.0ppm; range: 0.6-12.5 ppm) and child neuropsychological performance. Scores on 4 out of 11 neuropsychological tests were significantly associated with mothers' 3rd trimester CO exposures, including visuo-spatial integration (p<0.05), short-term memory recall (p<0.05), long-term memory recall (p<0.05), and fine motor performance (p<0.01) measured using the Bender Gestalt-II's Copy, Immediate Recall, and an adapted version of a Delayed Recall Figures drawing, and the Reitan-Indiana's Finger Tapping Tests, respectively. These 4 significant finding persisted with adjustment for child sex, age, visual acuity, and household assets (socio-economic status). Summary performance scores were also significantly associated with maternal 3rd trimester CO when adjusted for these covariates. Other variables accounting for variance but were excluded in our final multiple regression models included the following: HOME environment stimulation score, child examiner, WHO height-for-age percentile, and age that the infant stopped breastfeeding. This seems to be the first study on woodsmoke exposure and neurodevelopment, and the first longitudinal birth cohort study on chronic early life CO exposures, determined by high quality measures of mothers' and infants' personal CO exposures, and using well

  20. 10Be application to soil development on Marion Island, southern Indian Ocean

    NASA Astrophysics Data System (ADS)

    Haussmann, N.; Aldahan, A.; Boelhouwers, J.; Possnert, G.

    2010-04-01

    Marion Island, located in the southern Indian Ocean, constitutes the summit of an active shield volcano. It is a small terrestrial environment where glacially abraded bedrock became exposed c × 10 kyr ago. These conditions provide an interesting possibility for the assessment of 10Be accumulation rates and their application to soil erosion studies on the island. 10Be concentrations were measured in precipitation, soil profiles and an Azorella selago cushion plant. The data reveal a 10Be precipitation flux several times higher than model prediction. Estimation of the 10Be accumulation based on the soil inventory suggests a span between 2000 and 7000 yr. This time span is not in accordance with the accepted notion that the island was covered with ice about 10,000 yr ago and suggests either removal of 10Be from the soil profile, an overestimated Holocene 10Be-flux or a delayed soil development history. Our results provide new data on 10Be concentrations from the sub-Antarctic islands and contribute towards enlarging the southern-hemisphere 10Be database.

  1. Exposure to omega-3 fatty acids at early age accelerate bone growth and improve bone quality.

    PubMed

    Koren, Netta; Simsa-Maziel, Stav; Shahar, Ron; Schwartz, Betty; Monsonego-Ornan, Efrat

    2014-06-01

    Omega-3 fatty acids (FAs) are essential nutritional components that must be obtained from foods. Increasing evidence validate that omega-3 FAs are beneficial for bone health, and several mechanisms have been suggested to mediate their effects on bone, including alterations in calcium absorption and urinary calcium loss, prostaglandin synthesis, lipid oxidation, osteoblast formation and inhibition of osteoclastogenesis. However, to date, there is scant information regarding the effect of omega-3 FAs on the developing skeleton during the rapid growth phase. In this study we aim to evaluate the effect of exposure to high levels of omega-3 FAs on bone development and quality during prenatal and early postnatal period. For this purpose, we used the fat-1 transgenic mice that have the ability to convert omega-6 to omega-3 fatty acids and the ATDC5 chondrogenic cell line as models. We show that exposure to high concentrations of omega-3 FAs at a young age accelerates bone growth through alterations of the growth plate, associated with increased chondrocyte proliferation and differentiation. We further propose that those effects are mediated by the receptors G-protein coupled receptor 120 (GPR120) and hepatic nuclear factor 4α, which are expressed by chondrocytes in culture. Additionally, using a combined study on the structural and mechanical bone parameters, we show that high omega-3 levels contribute to superior trabecular and cortical structure, as well as to stiffer bones and improved bone quality. Most interestingly, the fat-1 model allowed us to demonstrate the role of maternal high omega-3 concentration on bone growth during the gestation and postnatal period.

  2. Age-dependent effects of initial exposure to nicotine on serotonin neurons.

    PubMed

    Bang, S J; Commons, K G

    2011-04-14

    Adolescence is a critical vulnerable period during which exposure to nicotine greatly enhances the possibility to develop drug addiction. Growing evidence suggests that serotonergic (5-HT) neurotransmission may contribute to the initiation and maintenance of addictive behavior. As the dorsal raphe (DR) and median raphe (MnR) nuclei are the primary 5-HT source to the forebrain, the current study tested the hypothesis that there are age-dependent effects of acute nicotine administration on activation of 5-HT neurons within these regions. Both adolescent (Postnatal day 30) and adult (Postnatal day 70) male Sprague-Dawley rats received subcutaneous injection of either saline or nicotine (0.2, 0.4, or 0.8 mg/kg). Subsequently, the number of 5-HT cells that were double-labeled for Fos and tryptophan hydroxylase was counted in seven subregions within the DR and the entire MnR. The results show that acute nicotine injection induces Fos expression in 5-HT neurons in a region-specific manner. In addition, adolescents show broader regional activations at either a lower (0.2 mg/kg) and a higher (0.8 mg/kg) dose of nicotine, displaying a unique U-shape response curve across doses. In contrast, 5-HT cells with activated Fos expression were restricted to fewer regions in adults, and the patterns of expression were more consistent across doses. The results reveal dose-dependent effects of nicotine during adolescence with apparent sensitization at different ends of the dosage spectrum examined compared to adults. These data indicate that initial exposure to nicotine may have unique effects in adolescence on the ascending 5-HT system, with the potential for consequences on the affective-motivational qualities of the drug and the subsequent propensity for repeated use.

  3. Early life microbial exposure and fractional exhaled nitric oxide in school-age children: a prospective birth cohort study

    PubMed Central

    2013-01-01

    Background Inflammation is a key factor in the pathogenesis of respiratory diseases. Early life exposure to microbial agents may have an effect on the development of the immune system and on respiratory health later in life. In the present work we aimed to evaluate the associations between early life microbial exposures, and fractional exhaled nitric oxide (FeNO) at school age. Methods Endotoxin, extracellular polysaccharides (EPS) and β(1,3)-D-glucan were measured in living room dust collected at 2–3 months of age in homes of participants of three prospective European birth cohorts (LISA, n = 182; PIAMA, n = 244; and INMA, n = 355). Home dampness and pet ownership were periodically reported by the parents through questionnaires. FeNO was measured at age 8 for PIAMA and at age 10/11 for LISA and INMA. Cohort-specific associations between the indoor microbial exposures and FeNO were evaluated using multivariable regression analyses. Estimates were combined using random-effects meta-analyses. Results FeNO at school age was lower in children exposed to endotoxin at age 2–3 months (β -0.05, 95% confidence interval (CI) -0.10;-0.01) and in children with reported dog ownership during the first two years of life (GM ratio 0.82, CI 0.70-0.96). FeNO was not significantly associated with early life exposure to EPS, β(1,3)-D-glucan, indoor dampness and cat ownership. Conclusion Early life exposure to bacterial endotoxin and early life dog ownership are associated with lower FeNO at school age. Further studies are needed to confirm our results and to unravel the underlying mechanisms and possible clinical relevance of this finding. PMID:24295277

  4. Meteoric 10Be in Lake Cores as a Measure of Climatic and Erosional Change

    NASA Astrophysics Data System (ADS)

    Jensen, R. E.; Dixon, J. L.

    2015-12-01

    Utilization of meteoric 10Be as a paleoenvironmental proxy has the potential to offer new insights into paleoprecipitation records and paleoclimate models, as well as to long-term variations in erosion with climate. The delivery of meteoric 10Be to the surface varies with precipitation and its strong adsorption to sediment has already proven useful in studies of erosion. Thus, it is likely meteoric 10Be concentrations in lake sediments vary under both changing climate and changing sediment influx. Assessment of the relative importance of these changes requires the comparison of 10Be concentrations in well-dated lake cores with independent paleoenvironmental proxies, including oxygen isotope, pollen, and charcoal records, as well as variation in geochemical composition of the sediments. Blacktail Pond details 15,000 years of climatic change in the Yellowstone region. We develop a new model framework for predicting meteoric 10Be concentrations with depth in the core, based on sedimentation rates of both lake-derived and terrigenous sediments and changes in the flux of meteoric 10Be with precipitation. Titanium concentrations and previously determined 10Be concentrations in wind-derived loess provide proxies for changing delivery of 10Be to the lake by terrigenous sources. We use existing paleoenvironmental data obtained from this core and the surrounding region to develop models for changing rainfall across the region and predict meteoric 10Be delivery to the lake by precipitation. Based on a suite of ~10 models, sedimentation rate is the primary control of meteoric 10Be in the Blacktail Pond core unless terrestrial input is very high, as it was post-glacial in the early Holocene when the lake experienced a high influx of loess and terrigenous sediments. We used these models to inform sample selection for 10Be analysis along the Blacktail pond core. Core sediments are processed for meteoric 10Be analysis using sequential digestions and standard extraction procedures

  5. A model-based evaluation of sedimentary reconstructions of 10Be production rates

    NASA Astrophysics Data System (ADS)

    Carney, Lewis; Plancherel, Yves; Khatiwala, Samar; Henderson, Gideon

    2016-04-01

    Atmospheric production of 10Be is small when solar activity and, therefore, solar magnetic field and total solar irradiance are strong. Variations in solar activity affect climate and the production of other climate-relevant isotopes, such as 14C. Solar activity is thus an important variable to constrain. Since 10Be production is clearly related to solar activity and the cycle of beryllium is simpler than that of carbon, 10Be records in ice cores have been used to reconstruct total solar irradiance variability. Unfortunately, 10Be records in ice cores are not only affected by variations in atmospheric production, but are also modulated by changes in wind patterns since spatiotemporal atmospheric 10Be gradients are quite large. In that context, sedimentary 10Be records from the abyssal ocean could be of great interest: since the residence time of 10Be in the ocean is thought to be comparable to the overturning time-scale of the ocean, spatial 10Be gradients may be relatively weaker than those in the atmosphere. Under these conditions, regional oceanic variability should only weakly affect the distribution of 10Be in the ocean and local sedimentary 10Be records are expected to represent the global average 10Be production better than 10Be measured in ice cores. We here show results from a global ocean model of 10Be that we use to investigate the spatial variability of simulated sedimentary 10Be records and test the sensitivity of the 10Be sedimentary flux to uncertainties in the circulation field and in the particle chemistry of beryllium. Our ocean model is based on the Transport Matrix method. The surface 10Be input fluxes are taken from atmospheric model simulations. Our model experiments, constrained by available dissolved 10Be data, show that there exist regions in the ocean where the sedimentary 10Be flux is relatively insensitive to changes in input patterns and magnitudes, assumed particle chemistry and flux patterns, and ocean circulation. We submit that

  6. In utero bisphenol A exposure disrupts germ cell nest breakdown and reduces fertility with age in the mouse

    SciTech Connect

    Wang, Wei Hafner, Katlyn S. Flaws, Jodi A.

    2014-04-15

    Bisphenol A (BPA) is a known reproductive toxicant in rodents. However, the effects of in utero BPA exposure on early ovarian development and the consequences of such exposure on female reproduction in later reproductive life are unclear. Thus, we determined the effects of in utero BPA exposure during a critical developmental window on germ cell nest breakdown, a process required for establishment of the finite primordial follicle pool, and on female reproduction. Pregnant FVB mice (F0) were orally dosed daily with tocopherol-striped corn oil (vehicle), diethylstilbestrol (DES; 0.05 μg/kg, positive control), or BPA (0.5, 20, and 50 μg/kg) from gestational day 11 until birth. Ovarian morphology and gene expression profiles then were examined in F1 female offspring on postnatal day (PND) 4 and estrous cyclicity was examined daily after weaning for 30 days. F1 females were also subjected to breeding studies with untreated males at three to nine months. The results indicate that BPA inhibits germ cell nest breakdown via altering expression of selected apoptotic factors. BPA also significantly advances the age of first estrus, shortens the time that the females remain in estrus, and increases the time that the females remain in metestrus and diestrus compared to controls. Further, F1 females exposed to low doses of BPA exhibit various fertility problems and have a significantly higher percentage of dead pups compared to controls. These results indicate that in utero exposure to low doses of BPA during a critical ovarian developmental window interferes with early ovarian development and reduces fertility with age. - Highlights: • In utero BPA exposure inhibits germ cell nest breakdown in female mouse offspring. • In utero BPA exposure alters expression of apoptosis regulators in the ovaries of mouse offspring. • In utero BPA exposure advances first estrus age and alters cyclicity in mouse offspring. • In utero BPA exposure causes various fertility problems in

  7. Media Exposure, Body Dissatisfaction, and Disordered Eating in Middle-Aged Women: A Test of the Sociocultural Model of Disordered Eating

    ERIC Educational Resources Information Center

    Slevec, Julie; Tiggemann, Marika

    2011-01-01

    The primary aim of our study was to examine the influence of media exposure on body dissatisfaction and disordered eating in middle-aged women. A sample of 101 women, aged between 35 and 55 years, completed questionnaire measures of media exposure, thin-ideal internalization, social comparison, appearance investment, aging anxiety, body…

  8. Cosmic ray exposure ages of iron meteorites, complex irradiation and the constancy of cosmic ray flux in the past

    NASA Technical Reports Server (NTRS)

    Marti, K.; Lavielle, B.; Regnier, S.

    1984-01-01

    While previous calculations of potassium ages assumed a constant cosmic ray flux and a single stage (no change in size) exposure of iron meteorites, present calculations relaxed these constancy assumptions and the results reveal multistage irradiations for some 25% of the meteorites studied, implying multiple breakup in space. The distribution of exposure ages suggests several major collisions (based on chemical composition and structure), although the calibration of age scales is not yet complete. It is concluded that shielding-corrected (corrections which depend on size and position of sample) production rates are consistent for the age bracket of 300 to 900 years. These production rates differ in a systematic way from those calculated for present day fluxes of cosmic rays (such as obtained for the last few million years).

  9. Simulating ice core 10Be on the glacial-interglacial timescale

    NASA Astrophysics Data System (ADS)

    Elsässer, C.; Wagenbach, D.; Levin, I.; Stanzick, A.; Christl, M.; Wallner, A.; Kipfstuhl, S.; Seierstad, I. K.; Wershofen, H.; Dibb, J.

    2014-02-01

    10Be ice core measurements are an important tool for paleoclimate research, e.g. allowing for the reconstruction of past solar activity or variation in the natural 14C production rate. However, especially on multi-millennial timescales, the share of production and climate induced variations of respective 10Be ice core records is still up to debate. Here we present the first quantitative climatological model of the 10Be ice concentration up to the glacial-interglacial timescale. The model approach is composed of (i) a coarse resolution global atmospheric transport model and (ii) a local 10Be air-firn-transfer model. Extensive global-scale observational data of short-lived radionuclides as well as new polar 10Be snow pit measurements are used for model calibration and validation. Being specifically configured for polar 10Be, this tool thus allows for a straight-forward investigation of production and non-production related modulation of this nuclide. We find that the polar 10Be ice concentration does not record a globally mixed cosmogenic production signal. In fact, the geomagnetic modulation of Greenland 10Be is up to 50% lower than in case of the global atmospheric 10Be inventory. Using geomagnetic modulation and revised Greenland snow accumulation rate changes as model input we simulate the observed Greenland Summit (GRIP and GISP2) 10Be ice core records over the last 75 kyr (on the GICC05modelext timescale). We show that our basic model is capable to reproduce the largest portion of the observed 10Be changes. However, model-measurements differences exhibit multi-millennial oscillations with amplitudes up to 87% of the mean observed Holocene 10Be concentration. Focusing on the (12-37) kyr b2k (before the year 2000 AD) period, mean model-measurements differences of 30% cannot be imputed to production changes. However, unconsidered climate-induced changes could likely explain the model shortcomings. In fact, the 10Be ice concentration is very sensitive to snow

  10. Assessing soil fluxes using meteoric 10Be: development and application of the Be2D model

    NASA Astrophysics Data System (ADS)

    Campforts, Benjamin; Govers, Gerard; Vanacker, Veerle; Baken, Stijn; Smolders, Erik; Vanderborght, Jan

    2015-04-01

    Meteoric 10Be is a promising and increasingly popular tool to better understand soil fluxes at different timescales. Unlike other, more classical, methods such as the study of sedimentary archives it enables a direct coupling between eroding and deposition sites. However, meteoric 10Be can be mobilized within the soil. Therefore, spatial variations in meteoric 10Be inventories cannot directly be translated into spatial variations in erosion and sedimentation rates: a correct interpretation of measured 10Be inventories requires that both lateral and vertical movement of meteoric 10Be are accounted for. Here, we present a spatially explicit 2D model that allows to simulate the behaviour of meteoric 10Be in the soil system over timescales of up to 1 million year and use the model to investigate the impact of accelerated erosion on meteoric 10Be inventories. The model consists of two parts. A first component deals with advective and diffusive mobility within the soil profile, whereas a second component describes lateral soil (and meteoric 10Be) fluxes over the hillslope. Soil depth is calculated dynamically, accounting for soil production through weathering and lateral soil fluxes. Different types of erosion such as creep, water and tillage erosion are supported. Model runs show that natural soil fluxes can be well reconstructed based on meteoric 10Be inventories, and this for a wide range of geomorphological and pedological conditions. However, extracting signals of human impact and distinguishing them from natural soil fluxes is only feasible when the soil has a rather high retention capacity so that meteoric 10Be is retained in the top soil layer. Application of the Be2D model to an existing data set in the Appalachian Mountains [West et al.,2013] using realistic parameter values for the soil retention capacity as well as for vertical advection resulted in a good agreement between simulated and observed 10Be inventories. This confirms the robustness of the model. We

  11. Effect of tobacco smoke exposure during pregnancy and preschool age on growth from birth to adolescence: a cohort study

    PubMed Central

    2014-01-01

    Background There is strong evidence of an association between maternal smoking during pregnancy and restriction of intrauterine growth, but the effects of this exposure on postnatal linear growth are not well defined. Furthermore, few studies have investigated the role of tobacco smoke exposure also after pregnancy on linear growth until adolescence. In this study we investigated the effect of maternal smoking exposure during pregnancy and preschool age on linear growth from birth to adolescence. Methods We evaluated a cohort of children born between 1994 and 1999 in Cuiabá, Brazil, who attended primary health clinics for vaccination between the years 1999 and 2000 (at preschool age) and followed-up after approximately ten years. Individuals were located in public and private schools throughout the country using the national school census. Height/length was measured, and length at birth was collected at maternity departments. Stature in childhood and adolescence was assessed using the height-for-age index sex-specific expressed as z-score from curves published by the World Health Organization. Linear mixed effects models were used to estimate the association between exposure to maternal smoking, during pregnancy and preschool age, and height of children assessed at birth, preschool and school age, adjusted for age of the children. Results We evaluated 2405 children in 1999–2000, length at birth was obtained from 2394 (99.5%), and 1716 at follow-up (71.4% of baseline), 50.7% of the adolescents were male. The z-score of height-for-age was lower among adolescents exposed to maternal smoking both during pregnancy and childhood (p < 0.01). Adjusting for age, sex, maternal height, maternal schooling, socioeconomic position at preschool age, and breastfeeding, children exposed to maternal smoking both during pregnancy and preschool age showed persistent lower height-for-age since birth to adolescence (coefficient: −0.32, p < 0.001) compared to non

  12. Meteoric 10Be as a tool to investigate human induced soil fluxes: a conceptual model

    NASA Astrophysics Data System (ADS)

    Campforts, Benjamin; Govers, Gerard; Vanacker, Veerle; De Vente, Joris; Boix-Fayos, Carolina; Minella, Jean; Baken, Stijn; Smolders, Erik

    2014-05-01

    The use of meteoric 10Be as a tool to understand long term landscape behavior is becoming increasingly popular. Due its high residence time, meteoric 10Be allows in principle to investigate in situ erosion rates over time scales exceeding the period studied with classical approaches such as 137Cs. The use of meteoric 10Be strongly contributes to the traditional interpretation of sedimentary archives which cannot be unequivocally coupled to sediment production and could provide biased information over longer time scales (Sadler, 1981). So far, meteoric 10Be has successfully been used in geochemical fingerprinting of sediments, to date soil profiles, to assess soil residence times and to quantify downslope soil fluxes using accumulated 10Be inventories along a hill slope. However, less attention is given to the potential use of the tracer to directly asses human induced changes in soil fluxes through deforestation, cultivation and reforestation. A good understanding of the processes governing the distribution of meteoric 10Be both within the soil profile and at landscape scale is essential before meteoric 10Be can be successfully applied to assess human impact. We developed a spatially explicit 2D-model (Be2D) in order to gain insight in meteoric 10Be movement along a hillslope that is subject to human disturbance. Be2D integrates both horizontal soil fluxes and vertical meteoric 10Be movement throughout the soil prolife. Horizontal soil fluxes are predicted using (i) well studied geomorphical laws for natural erosion and soil formation as well as (ii) human accelerated water and tillage erosion. Vertical movement of meteoric 10Be throughout the soil profile is implemented by inserting depth dependent retardation calculated using experimentally determined partition coefficients (Kd). The model was applied to different environments such as (i) the Belgian loess belt, characterized by aeolian deposits enriched in inherited meteoric 10Be, (ii) highly degraded and stony

  13. A preliminary study on the use of (10)Be in forensic radioecology of nuclear explosion sites.

    PubMed

    Whitehead, N E; Endo, S; Tanaka, K; Takatsuji, T; Hoshi, M; Fukutani, S; Ditchburn, R G; Zondervan, A

    2008-02-01

    Cosmogenic (10)Be, known for use in dating studies, unexpectedly is also produced in nuclear explosions with an atom yield almost comparable to (e.g.) (137)Cs. There are major production routes via (13)C(n, alpha)(10)Be, from carbon dioxide in the air and the organic explosives, possibly from other bomb components and to a minor extent from the direct fission reaction. Although the detailed bomb components are speculative, carbon was certainly present in the explosives and an order of magnitude calculation is possible. The (n, alpha) cross-section was determined by irradiating graphite in a nuclear reactor, and the resulting (10)Be estimated by Accelerator Mass Spectrometry (AMS) giving a cross-section of 34.5+/-0.7mb (6-9.3MeV), within error of previous work. (10)Be should have applications in forensic radioecology. Historical environmental samples from Hiroshima, and Semipalatinsk (Kazakhstan) showed two to threefold (10)Be excesses compared with the background cosmogenic levels. A sample from Lake Chagan (a Soviet nuclear cratering experiment) contained more (10)Be than previously reported soils. (10)Be may be useful for measuring the fast neutron dose near the Hiroshima bomb hypocenter at neutron energies double those previously available.

  14. Interaction between age of irradiation and age of testing in the disruption of operant performance using a ground-based model for exposure to cosmic rays.

    PubMed

    Rabin, Bernard M; Joseph, James A; Shukitt-Hale, Barbara; Carrihill-Knoll, Kirsty L

    2012-02-01

    Previous research has shown a progressive deterioration in cognitive performance in rats exposed to (56)Fe particles as a function of age. The present experiment was designed to evaluate the effects of age of irradiation independently of the age of testing. Male Fischer-344 rats, 2, 7, 12, and 16 months of age, were exposed to 25-200 cGy of (56)Fe particles (1,000 MeV/n). Following irradiation, the rats were trained to make an operant response on an ascending fixed-ratio reinforcement schedule. When performance was evaluated as a function of both age of irradiation and testing, the results showed a significant effect of age on the dose needed to produce a performance decrement, such that older rats exposed to lower doses of (56)Fe particles showed a performance decrement compared to younger rats. When performance was evaluated as a function of age of irradiation with the age of testing held constant, the results indicated that age of irradiation was a significant factor influencing operant responding, such that older rats tested at similar ages and exposed to similar doses of (56)Fe particles showed similar performance decrements. The results are interpreted as indicating that the performance decrement is not a function of age per se, but instead is dependent upon an interaction between the age of irradiation, the age of testing, and exposure to HZE particles. The nature of these effects and how age of irradiation affects cognitive performance after an interval of 15 to 16 months remains to be established.

  15. Exposure to violence during childhood is associated with telomere erosion from 5 to 10 years of age: a longitudinal study.

    PubMed

    Shalev, I; Moffitt, T E; Sugden, K; Williams, B; Houts, R M; Danese, A; Mill, J; Arseneault, L; Caspi, A

    2013-05-01

    There is increasing interest in discovering mechanisms that mediate the effects of childhood stress on late-life disease morbidity and mortality. Previous studies have suggested one potential mechanism linking stress to cellular aging, disease and mortality in humans: telomere erosion. We examined telomere erosion in relation to children's exposure to violence, a salient early-life stressor, which has known long-term consequences for well-being and is a major public-health and social-welfare problem. In the first prospective-longitudinal study with repeated telomere measurements in children while they experienced stress, we tested the hypothesis that childhood violence exposure would accelerate telomere erosion from age 5 to age 10 years. Violence was assessed as exposure to maternal domestic violence, frequent bullying victimization and physical maltreatment by an adult. Participants were 236 children (49% females; 42% with one or more violence exposures) recruited from the Environmental-Risk Longitudinal Twin Study, a nationally representative 1994-1995 birth cohort. Each child's mean relative telomere length was measured simultaneously in baseline and follow-up DNA samples, using the quantitative PCR method for T/S ratio (the ratio of telomere repeat copy numbers to single-copy gene numbers). Compared with their counterparts, the children who experienced two or more kinds of violence exposure showed significantly more telomere erosion between age-5 baseline and age-10 follow-up measurements, even after adjusting for sex, socioeconomic status and body mass index (B=-0.052, s.e.=0.021, P=0.015). This finding provides support for a mechanism linking cumulative childhood stress to telomere maintenance, observed already at a young age, with potential impact for life-long health.

  16. Age-at-exposure effects on risk estimates for non-cancer mortality in the Japanese atomic bomb survivors.

    PubMed

    Zhang, Wei; Muirhead, Colin R; Hunter, Nezahat

    2005-12-01

    Statistically significant increases in non-cancer disease mortality with radiation dose have been observed among survivors of the atomic bombings of Hiroshima and Nagasaki. The increasing trends arise particularly for diseases of the circulatory, digestive, and respiratory systems. Rates for survivors exposed to a dose of 1 Sv are elevated by about 10%, a smaller relative increase than that for cancer. The aetiology of this increased risk is not yet understood. Neither animal nor human studies have found clear evidence for excess non-cancer mortality at the lower range of doses received by A-bomb survivors. In this paper, we examine the age and time patterns of excess risks in the A-bomb survivors. The results suggest that the excess relative risk of non-cancer disease mortality might be highest for exposure at ages 30-49 years, and that those exposed at ages 0-29 years might have a very low excess relative risk compared with those exposed at older ages. The differences in excess relative risk for different age-at-exposure groups imply that the dose response relationships for non-cancer disease mortality need to be modelled with adjustment for age-at-exposure.

  17. Modifiable maternal exposures and offspring blood pressure: a review of epidemiological studies of maternal age, diet, and smoking.

    PubMed

    Brion, Marie-Jo A; Leary, Sam D; Lawlor, Debbie A; Smith, George Davey; Ness, Andy R

    2008-06-01

    Prenatal programming of adult disease is well established in animals. In humans the impact of common in utero exposures on long-term offspring health is less clear. We reviewed epidemiology studies of modifiable maternal exposures and offspring blood pressure (BP). Three maternal exposures were identified for review and meta-analyzed where possible: smoking during pregnancy, diet, and age at childbirth. Meta-analysis suggested there was a modest association between higher offspring BP and prenatal exposure to smoke (confounder-adjusted beta = 0.62 mm Hg, 95% confidence interval: 0.19-1.05, I = 16.4%). However, the level of confounder adjustment varied between studies, which in some studies attenuated the association to the null. There was no strong evidence that any component of maternal diet during pregnancy (maternal protein, energy, calcium, and various other nutrients) influences offspring BP. The results of studies of maternal age varied and there was strong evidence of heterogeneity in the pooled analysis. The association with maternal age, if present, was modest (confounder-adjusted beta = 0.09 mm Hg/y, 95% confidence interval: -0.03 to 0.21, I = 89.8%). In sum, there is little empirical evidence that the maternal exposures reviewed program offspring BP. Other components of offspring health may be more susceptible to effects of programming in utero.

  18. Occupational pesticide exposure in early pregnancy associated with sex-specific neurobehavioral deficits in the children at school age.

    PubMed

    Andersen, Helle R; Debes, Fróði; Wohlfahrt-Veje, Christine; Murata, Katsuyuki; Grandjean, Philippe

    2015-01-01

    Prenatal exposure to pesticides may affect neurodevelopment, while the impact of modern pesticides is unclear. From 1997-2001, women working in greenhouse horticultures were recruited at the beginning of their pregnancy. Based on detailed interview of the women and their employers, those categorized as occupationally exposed to pesticides were moved to unexposed work functions or went on paid leave, while women without any exposure were considered unexposed controls. Of the resulting birth cohort of 203 children, 133 (65%) were examined at age 6 to 11 years together with 44 newly recruited children of same age whose mothers were not occupationally exposed to pesticides in pregnancy. All children underwent a standardized examination including a battery of neurodevelopmental tests. Maternal occupational pesticide exposure in early pregnancy was associated with prolonged brainstem auditory evoked potential latencies in the children as a whole and with impaired neuropsychological function in girls, while no effect was apparent in boys. In girls, language and motor speed functions were significantly inversely associated with prenatal exposure, and a non-significant tendency toward decreased function was also seen for other neuropsychological outcomes. A structural equation model that combined all these test results showed an overall impaired neuropsychological function in girls prenatally exposed to pesticides. Thus, our findings suggest an adverse effect of maternal occupational pesticide exposure on their children's neurodevelopment, despite the fact that the exposures occurred solely during early pregnancy and under well regulated working conditions, where special measures to protect pregnant women were applied.

  19. Age sensitivity of juvenile mussels (Utterbackia imbeciles Say) to copper and cadmium exposure

    SciTech Connect

    Warren, L.W.; Klaine, S.J.

    1994-12-31

    In recent years, there has been increased interest in using early life stages of freshwater bivalves to test the toxicity of dissolved constituents in water. The authors have developed laboratory and in situ assays with artificially cultured Utterbackia imbecillis to examine effects of contaminants and existing conditions in embayments and rivers on mortality and reproductive success of unionid mussels. Age sensitivity of U. imbecillis to Cd and Cu was examined using both static acute and 8-day static renewal bioassays. Both aqueous and sediment exposures demonstrated greater sensitivity to Cd than Cu. LC{sub 50}`s for two-day old (2d) and 9d mussels were approximately half the LC{sub 50} calculated for 16d mussels in 48-hr bioassays with Cd. Additionally, acute assays were repeated twice to examine variability in response between different mussel cultures to the two metals. The results of this work reinforce the potential of juvenile U. imbecillis as a standard toxicity test organism for water-borne and sediment contamination.

  20. Early to Late Pleistocene history of debris-flow fan evolution in western Death Valley (California) using cosmogenic 10Be and 26Al

    NASA Astrophysics Data System (ADS)

    Dühnforth, Miriam; Densmore, Alexander L.; Ivy-Ochs, Susan; Allen, Philip; Kubik, Peter W.

    2017-03-01

    Debris-flow fans with depositional records over several 105 years may be useful archives for the understanding of fan construction by debris flows and post-depositional surface modification over long timescales. Reading these archives, however, requires that we establish the temporal and spatial pattern of debris-flow activity over time. We used a combination of geomorphic mapping of fan surface characteristics, digital topographic analysis, and cosmogenic radionuclide dating using 10Be and 26Al to study the evolution of the Warm Springs fan on the west side of southern Death Valley, California. The 10Be concentrations yield dates that vary from 989 ± 43 to 595 ± 17 ka on the proximal fan and between 369 ± 13 and 125 ± 5 ka on distal fan surfaces. The interpretation of these results as true depositional ages though is complicated by high inheritance with a minimum of 65 ka measured at the catchment outlet and of at least 125 ka at the distal fan. Results from the 26Al measurements suggest that most sample locations on the fan surfaces underwent simple exposure and were not affected by complex histories of burial and re-exposure. This implies that Warm Springs fan is a relatively stable landform that underwent several 105 years of fan aggradation before fan head incision caused abandonment of the proximal and central fan surfaces and deposition continued on a younger unit at the distal fan. We show that the primary depositional debris-flow morphology is eliminated over a time scale of less than 105 years, which prevents the delineation of individual debris flows as well as the precise reconstruction of lateral shifts in deposition as we find it on younger debris-flow fans. Secondary post-depositional processes control subsequent evolution of surface morphology with the dissection of planar surfaces while smoothing of convex-up interfluves between incised channels continues through time.

  1. Evolution of phenolic compounds and astringency during aging of red wine: effect of oxygen exposure before and after bottling.

    PubMed

    Gambuti, Angelita; Rinaldi, Alessandra; Ugliano, Maurizio; Moio, Luigi

    2013-02-27

    The aim of this study was to evaluate the effect of oxygen exposure of red wine, before (micro-oxygenation) and after (nano-oxygenation) bottling, on the phenolic composition and astringency of wine. The astringency was evaluated by sensory analysis and by a method based on the SDS-PAGE of salivary proteins after reaction of saliva with wine (SPI, saliva precipitation index). Micro-oxygenation caused a stabilization of color, but this effect disappeared after long aging. For the wine with the lower pH a decrease of wine astringency and SPI was observed 42 months after micro-oxygenation. Oxygen ingress through the closure postbottling was positively correlated with the decrease of SPI. Therefore, the astringency and reactivity of wines toward salivary proteins of a bottled red wine can be modulated by controlled oxygen exposure during aging. For both experiments the effect of oxygen exposure depended on wine composition.

  2. Dielectric properties of tissues; variation with age and their relevance in exposure of children to electromagnetic fields; state of knowledge.

    PubMed

    Peyman, Azadeh

    2011-12-01

    This paper reviews and summarises the state of knowledge on dielectric properties of tissues; in particular those obtained as a function of age. It also examines the impact of variation in dielectric data on the outcome of recent dosimetric studies assessing the exposure of children to electromagnetic fields.

  3. Infantile postnatal exposure to lead (Pb) enhances tau expression in the cerebral cortex of aged mice: relevance to AD.

    PubMed

    Bihaqi, Syed Waseem; Bahmani, Azadeh; Adem, Abdu; Zawia, Nasser H

    2014-09-01

    The sporadic nature in over 90% of Alzheimer's disease (AD) cases, the differential susceptibility and course of illness, and latent onset of the disease suggest involvement of an environmental component in the etiology of late onset AD (LOAD). Recent reports from our lab have demonstrated that molecular alterations favor abundant tau phosphorylation and immunoreactivity in the frontal cortex of aged primates with infantile lead (Pb) exposure (Bihaqi and Zawia, 2013). Here we report that developmental Pb exposure results in elevation of protein and mRNA levels of tau in aged mice. Western blot analysis revealed aberrant site-specific tau hyperphosphorylation accompanied by elevated cyclin dependent kinase 5 (CDK5) levels in aged mice with prior Pb exposure. Mice with developmental Pb exposure also displayed altered protein ratio of p35/p25 with more Serine/Threonine phosphatase activity at old age. These changes favored increase in tau phosphorylation, thus providing evidence that neurodegenerative diseases may be in part due to environmental influences that occur during development.

  4. SUMMARY REPORT OF A PEER INVOLVEMENT WORKSHOP ON THE DEVELOPMENT OF AN EXPOSURE FACTORS HANDBOOK FOR THE AGING

    EPA Science Inventory

    EPA has released the final workshop report, Summary Report of a Peer Involvement Workshop on the Development of an Exposure Factors Handbook for the Aging. This report provides an overview of a meeting held February 14-15, 2007 which was organized to discuss factors affec...

  5. Oxidation and biodegradation of polyethylene films containing pro-oxidantadditives: Synergistic effects of sunlight exposure, thermal aging and fungal biodegradation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Synergistic effects of sunlight exposure, thermal aging and fungal biodegradation on the oxidation and biodegradation of linear low density poly (ethylene) PE-LLD films containing pro-oxidant were examined. To achieve oxidation and degradation, films were first exposed to the sunlight for 93 days du...

  6. Age assessment and implications of late Quaternary periglacial and paraglacial landforms on Muckish Mountain, northwest Ireland, based on Schmidt-hammer exposure-age dating (SHD)

    NASA Astrophysics Data System (ADS)

    Wilson, Peter; Matthews, John A.

    2016-10-01

    Schmidt-hammer exposure-age dating (SHD) was applied to a variety of late Quaternary periglacial and paraglacial landforms composed of coarse rock debris on Muckish Mountain, northwest Ireland. Landform ages were determined using a linear high-precision age-calibration curve, derived from young and old control surfaces of known age on the same rock type. The SHD ages represent maximum estimates of the time elapsed since the boulders stabilised and the landforms became inactive. Most ages are also minimum estimates for the start of landform development because older boulders are buried beneath the sampled surface boulders. Ages and 95% confidence intervals obtained for blockfield, boulder lobes and talus indicate these features were likely active during several of the early Holocene cold events evidenced in Greenland ice cores and North Atlantic sediment records. Activity ceased at different times ~ 9-7 ka BP. These landforms are the first indication of a geomorphological response to early Holocene cooling in the oceanic mountains of Ireland. Late Holocene ages, obtained for rock-slope failure run-out debris and debris cone boulders, overlap with shifts to cooler and/or wetter conditions, including the Little Ice Age. Geomorphological impacts associated with these changes in climate have not previously been recorded in the Irish uplands. The SHD results indicate that previously implied timings for the stabilisation of some accumulations of coarse rock debris on mountain slopes are in need of revision.

  7. Inter-comparison in 10Be analysis starting from pre-purified quartz

    NASA Astrophysics Data System (ADS)

    Schnabel, C.; Reinhardt, L.; Barrows, T. T.; Bishop, P.; Davidson, A.; Fifield, L. K.; Freeman, S.; Kim, J. Y.; Maden, C.; Xu, S.

    2007-06-01

    The results of the first international inter-comparison of 10Be analysis from quartz are presented. This inter-comparison includes the sample preparation starting from pre-purified quartz and AMS measurements at SUERC and ANU. Measured 10Be concentrations agree within their uncertainties for six out of seven samples with 10Be concentrations greater than 1 × 104 at/g quartz. This agreement and also the agreement of 10Be concentrations analysed from two aliquots of the same sample at SUERC indicate that addition of 9Be carrier before (used at ANU) or after quartz dissolution (used at SUERC apart from one aliquot of one sample) should not result in substantially different results.

  8. Correlated 50V and 10Be Excesses of Irradiation Origin in Refractory Inclusions from Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

    Sossi, P. A.; Moynier, F.; Chaussidon, M.; Gounelle, M.; Villeneuve, J.; Kato, C.

    2016-08-01

    The discovery in 7 CAIs of strong 50V excesses correlated with the presence of high 10Be/9Be ratios demonstrates that irradiation processes took place early in the accretion disk and allows to constrain the conditions of irradiation.

  9. Analysis of T = 1 {sup 10}B States Analogue to {sup 10}Be Cluster States

    SciTech Connect

    Uroic, M.; Miljanic, D.; Blagus, S.; Bogovac, M.; Prepolec, L.; Skukan, N.; Soic, N.; Majer, M.; Milin, M.; Lattuada, M.; Musumarra, A.; Acosta, L.

    2009-08-26

    Current status of the search for T = 1 cluster states in {sup 10}Be, {sup 10}B and {sup 10}C is presented. The best known of the three, {sup 10}Be, has an established rotational band (6.18, 7.54 and 10.15 MeV) with unusually large moment of inertia. Search of their isobaric analogue in {sup 10}B is presented, with emphasis on {sup 3}He+{sup 11}B reaction.

  10. Long-term cosmogenic 10Be catchment-wide erosion rates in the Kruger National Park

    NASA Astrophysics Data System (ADS)

    Glotzbach, Christoph; Paape, Alexander; Reinwarth, Bastian; Baade, Jussi; Miller, Jordan; Rowntree, Kate

    2015-04-01

    In this study we estimated long-term catchment-wide erosion rates in the central and southern Kruger National Park with cosmogenic 10Be analyses. Samples were collected in small catchments (2-100 km2) upstream of dams, which were used to determine short-term sediment yield rates. 10Be-derived erosion rates vary from 4-15 mm/kyr. Although there are significant site-specific differences in geomorphic parameters and precipitation we could not identify a single parameter controlling long-term erosion. Geomorphic fieldwork reveals that an unknown fraction of sampled sand-sized channel sediments derived from partly extensive and up to a few-meters deep gully erosion, which may lead to an overestimation of 10Be-derived erosion rates. Cosmogenic nuclide production is rapidly decreasing with depth and consequently the measured 10Be concentration of stream sediments is a mixture of (i) sand with high 10Be concentration from colluvial creep or sheet flow from hillslopes and (ii) sand with low 10Be concentration from gully erosion. To correct erosion rates, we quantify sediments derived from gullies using a combination of mapping gullies using remote sensing data and field work and geochemical characterisation of intact hillslopes and gully side walls.

  11. Preparation of ASTER in-house 10Be/9Be standard solutions

    NASA Astrophysics Data System (ADS)

    Braucher, R.; Guillou, V.; Bourlès, D. L.; Arnold, M.; Aumaître, G.; Keddadouche, K.; Nottoli, E.

    2015-10-01

    Since its commissioning in 2006, the commercially available certificated National Institute of Standards and Technology standard reference material NIST SRM 4325 is used at the French national facility ASTER (CEREGE, Aix-en-Provence) to normalize 10Be measurements. This standard solution being no longer disposable, we thus decided to produce in-house standards. As a first attempt, a STD-12 standard (10Be/9Be = (4.939 ± 0.053) × 10-12) has been prepared from 2.5 kg of marine sediments with an adapted chemical protocol. Then, a 10Be enriched solution of known concentration being available, a STD-11 standard (10Be/9Be = (1.191 ± 0.013) × 10-11) that will be used at ASTER in the near future to calibrate 10Be measurements and its dilution to the 10-14 level (STD-14 (10Be/9Be = (5.468 ± 0.064) × 10-14)) have been prepared from it.

  12. Metabolism and aging: effects of cold exposure on metabolic rate, body composition, and longevity in mice.

    PubMed

    Vaanholt, Lobke M; Daan, Serge; Schubert, Kristin A; Visser, G Henk

    2009-01-01

    The proposition that increased energy expenditure shortens life has a long history. The rate-of-living theory (Pearl 1928 ) states that life span and average mass-specific metabolic rate are inversely proportional. Originally based on interspecific allometric comparisons between species of mammals, the theory was later rejected on the basis of comparisons between taxa (e.g., birds have higher metabolic rates than mammals of the same size and yet live longer). It has rarely been experimentally tested within species. Here, we investigated the effects of increased energy expenditure, induced by cold exposure, on longevity in mice. Longevity was measured in groups of 60 male mice maintained at either 22 degrees C (WW) or 10 degrees C (CC) throughout adult life. Forty additional mice were maintained at both of these temperatures to determine metabolic rate (by stable isotope turnover, gas exchange, and food intake) as well as the mass of body and organs of subsets of animals at four different ages. Because energy expenditure might affect longevity by either accumulating damage or by instantaneously affecting mortality rate, we included a third group of mice exposed to 10 degrees C early in life and to 22 degrees C afterward (CW). Exposure to cold increased mean daily energy expenditure by ca. 48% (from 47.8 kJ d(-1) in WW to 70.6 kJ d(-1) in CC mice, with CW intermediate at 59.9 kJ d(-1)). However, we observed no significant differences in median life span among the groups (WW, 832 d; CC, 834 d; CW, 751 d). CC mice had reduced body mass (lifetime mean 30.7 g) compared with WW mice (33.8 g), and hence their lifetime energy potential (LEP) per gram whole-body mass had an even larger excess than per individual. Greenberg ( 1999 ) has pointed out that the size of the energetically costly organs, rather than that of the whole body, may be relevant for the rate-of-living idea. We therefore expressed LEP also in terms of energy expenditure per gram dry lean mass or per gram

  13. Exposure science in an age of rapidly changing climate: challenges and opportunities.

    PubMed

    LaKind, Judy S; Overpeck, Jonathan; Breysse, Patrick N; Backer, Lorrie; Richardson, Susan D; Sobus, Jon; Sapkota, Amir; Upperman, Crystal R; Jiang, Chengsheng; Beard, C Ben; Brunkard, J M; Bell, Jesse E; Harris, Ryan; Chretien, Jean-Paul; Peltier, Richard E; Chew, Ginger L; Blount, Benjamin C

    2016-11-01

    Climate change is anticipated to alter the production, use, release, and fate of environmental chemicals, likely leading to increased uncertainty in exposure and human health risk predictions. Exposure science provides a key connection between changes in climate and associated health outcomes. The theme of the 2015 Annual Meeting of the International Society of Exposure Science-Exposures in an Evolving Environment-brought this issue to the fore. By directing attention to questions that may affect society in profound ways, exposure scientists have an opportunity to conduct "consequential science"-doing science that matters, using our tools for the greater good and to answer key policy questions, and identifying causes leading to implementation of solutions. Understanding the implications of changing exposures on public health may be one of the most consequential areas of study in which exposure scientists could currently be engaged. In this paper, we use a series of case studies to identify exposure data gaps and research paths that will enable us to capture the information necessary for understanding climate change-related human exposures and consequent health impacts. We hope that paper will focus attention on under-developed areas of exposure science that will likely have broad implications for public health.

  14. Exposure science in an age of rapidly changing climate: challenges and opportunities

    PubMed Central

    LaKind, Judy S; Overpeck, Jonathan; Breysse, Patrick N; Backer, Lorrie; Richardson, Susan D; Sobus, Jon; Sapkota, Amir; Upperman, Crystal R; Jiang, Chengsheng; Beard, C Ben; Brunkard, J M; Bell, Jesse E; Harris, Ryan; Chretien, Jean-Paul; Peltier, Richard E; Chew, Ginger L; Blount, Benjamin C

    2016-01-01

    Climate change is anticipated to alter the production, use, release, and fate of environmental chemicals, likely leading to increased uncertainty in exposure and human health risk predictions. Exposure science provides a key connection between changes in climate and associated health outcomes. The theme of the 2015 Annual Meeting of the International Society of Exposure Science—Exposures in an Evolving Environment—brought this issue to the fore. By directing attention to questions that may affect society in profound ways, exposure scientists have an opportunity to conduct “consequential science”—doing science that matters, using our tools for the greater good and to answer key policy questions, and identifying causes leading to implementation of solutions. Understanding the implications of changing exposures on public health may be one of the most consequential areas of study in which exposure scientists could currently be engaged. In this paper, we use a series of case studies to identify exposure data gaps and research paths that will enable us to capture the information necessary for understanding climate change-related human exposures and consequent health impacts. We hope that paper will focus attention on under-developed areas of exposure science that will likely have broad implications for public health. PMID:27485992

  15. Simulating ice core 10Be on the glacial-interglacial timescale

    NASA Astrophysics Data System (ADS)

    Elsässer, C.; Wagenbach, D.; Levin, I.; Stanzick, A.; Christl, M.; Wallner, A.; Kipfstuhl, S.; Seierstad, I. K.; Wershofen, H.; Dibb, J.

    2015-02-01

    10Be ice core measurements are an important tool for paleoclimate research, e.g., allowing for the reconstruction of past solar activity or changes in the geomagnetic dipole field. However, especially on multi-millennial timescales, the share of production and climate-induced variations of respective 10Be ice core records is still up for debate. Here we present the first quantitative climatological model of the 10Be ice concentration up to the glacial-interglacial timescale. The model approach is composed of (i) a coarse resolution global atmospheric transport model and (ii) a local 10Be air-firn transfer model. Extensive global-scale observational data of short-lived radionuclides as well as new polar 10Be snow-pit measurements are used for model calibration and validation. Being specifically configured for 10Be in polar ice, this tool thus allows for a straightforward investigation of production- and non-production-related modulation of this nuclide. We find that the polar 10Be ice concentration does not immediately record the globally mixed cosmogenic production signal. Using geomagnetic modulation and revised Greenland snow accumulation rate changes as model input, we simulate the observed Greenland Summit (GRIP and GISP2) 10Be ice core records over the last 75 kyr (on the GICC05modelext timescale). We show that our basic model is capable of reproducing the largest portion of the observed 10Be changes. However, model-measurement differences exhibit multi-millennial trends (differences up to 87% in case of normalized to the Holocene records) which call for closer investigation. Focusing on the (12-37) b2k (before the year AD 2000) period, mean model-measurement differences of 30% cannot be attributed to production changes. However, unconsidered climate-induced changes could likely explain the model-measurement mismatch. In fact, the 10Be ice concentration is very sensitive to snow accumulation changes. Here the reconstructed Greenland Summit (GRIP) snow

  16. Be2D: A model to understand the distribution of meteoric 10Be in soilscapes

    NASA Astrophysics Data System (ADS)

    Campforts, Benjamin; Vanacker, Veerle; Vanderborght, Jan; Govers, Gerard

    2016-04-01

    Cosmogenic nuclides have revolutionised our understanding of earth surface process rates. They have become one of the standard tools to quantify soil production by weathering, soil redistribution and erosion. Especially Beryllium-10 has gained much attention due to its long half-live and propensity to be relatively conservative in the landscape. The latter makes 10Be an excellent tool to assess denudation rates over the last 1000 to 100 × 103 years, bridging the anthropogenic and geological time scale. Nevertheless, the mobility of meteoric 10Be in soil systems makes translation of meteoric 10Be inventories into erosion and deposition rates difficult. Here we present a coupled soil hillslope model, Be2D, that is applied to synthetic and real topography to address the following three research questions. (i) What is the influence of vertical meteoric Be10 mobility, caused by chemical mobility, clay translocation and bioturbation, on its lateral redistribution over the soilscape, (ii) How does vertical mobility influence erosion rates and soil residence times inferred from meteoric 10Be inventories and (iii) To what extent can a tracer with a half-life of 1.36 Myr be used to distinguish between natural and human-disturbed soil redistribution rates? The model architecture of Be2D is designed to answer these research questions. Be2D is a dynamic model including physical processes such as soil formation, physical weathering, clay migration, bioturbation, creep, overland flow and tillage erosion. Pathways of meteoric 10Be mobility are simulated using a two step approach which is updated each timestep. First, advective and diffusive mobility of meteoric 10Be is simulated within the soil profile and second, lateral redistribution because of lateral soil fluxes is calculated. The performance and functionality of the model is demonstrated through a number of synthetic and real model runs using existing datasets of meteoric 10Be from case-studies in southeastern US. Brute

  17. Cumulative systolic blood pressure exposure in relation to cognitive function in middle-aged and elderly adults

    PubMed Central

    Liu, Jie; Huang, Yuling; Chen, Guojuan; Liu, Xiaoxue; Wang, Zhijun; Cao, Yibin; Li, Haitao; Song, Lu; Li, Chunhui; Zhao, Hualing; Chen, Shuohua; Wang, Yiming; Zhang, Ruiying; Wang, Anxin; Wu, Shouling

    2016-01-01

    Abstract The association between systolic blood pressure (SBP) and cognitive function is controversial in elderly adults. In addition, few studies focused on the cumulative effect of SBP. We aimed to investigate the association between cumulative SBP exposure and cognitive function among middle-aged and elderly adults. The analysis was based on the Asymptomatic Polyvascular Abnormalities Community (APAC) study. The primary predictor was the cumulative SBP calculated by consecutive SBP values measured through baseline (2006–2007) up to the fourth examination (2012–2013). The cognitive function was estimated by mini-mental state examination (MMSE) in the fourth examination. Linear regression and logistic regression analyses were used to investigate the association between cumulative SBP and cognitive function. Among 2211 participants (41.4% female, aged 40–94 years), 167 (7.55%) were diagnosed with cognitive impairment (MMSE score < 24). Higher cumulative exposure to SBP (per SD increment) was independently associated with poor cognitive performance after controlling for multiple factors (P < 0.001). We observed nondifferential association between men and women. However, higher cumulative SBP in the adults aged ≥60 years had a stronger association with poor cognitive performance compared with that in adults aged 40 to 60 years. Greater exposure to cumulative SBP is associated with worse cognitive performance among middle-aged and elderly adults. This association is similar between men and women, but stronger in elderly adults. PMID:27902618

  18. Changes in Testicular Interstitial Connective Tissue of Hamsters (Mesocricetus auratus) During Ageing and After Exposure to Short Photoperiod.

    PubMed

    Beltrán-Frutos, E; Seco-Rovira, V; Ferrer, C; Martínez-Hernández, J; Madrid, J F; Sáez, F J; Canteras, M; Pastor, L M

    2016-02-01

    The testicular interstitium of Syrian hamster (Mesocricetus auratus) was studied during ageing and in testicular regression after exposure to a short photoperiod, in relation to the interstitial cells and their connective tissue. This tissue was assessed histochemically using Masson's trichrome technique and the expression of Heat Shock Protein 47 (HSP-47) and collagen IV (α5) was assessed in Leydig cells. Finally, an ultrastructural analysis of some cells of the testicular interstitium was made. Leydig cells were positive for HSP-47 and collagen IV (α5). Ageing did not change the parameters studied while the short photoperiod altered the synthetic activity of Leydig cells. The positivity index of these cells for HSP-47 was significantly higher in the regressed testis, but was lower for collagen IV (α5). During ageing no change were observed. Ultrastructural Leydig cells showed a discontinuous basal lamina that did not change during ageing. The basal lamina was not identified in Leydig cells regressed by exposure to a short photoperiod. In conclusion; the intertubular connective tissue suffers little change with age. By contrast, in the testis regressed after exposure to a short photoperiod the studied parameters related to the intertubular connective tissue were altered. These changes are probably related with the low synthetic activity of regressed Leydig cell.

  19. Single and repeated exposures to the volatile anesthetic isoflurane do not impair operant performance in aged rats.

    PubMed

    Walters, Jennifer L; Chelonis, John J; Fogle, Charles M; Orser, Beverley A; Paule, Merle G

    2016-09-01

    Postoperative Cognitive Dysfunction (POCD) is a complication that can occur in the elderly after anesthesia and surgery and is characterized by impairments in information processing, memory, and executive function. Currently, it is unclear whether POCD is due to the effects of surgery, anesthesia, or perhaps some interaction between these or other perioperative variables. Studies in rodents suggest that the development of POCD may be related directly to anesthesia-induced neuroactivity. Volatile anesthetics have been shown to increase cellular inflammation and apoptosis within the hippocampus of aged rodents, while producing corresponding impairments in hippocampal-dependent brain functions. However, it is unclear whether volatile anesthetics can affect additional aspects of cognition that do not primarily depend upon the hippocampus. The purpose of this study was to use established operant tests to examine the effects of isoflurane on aspects of behavioral inhibition, learning, and motivation in aged rats. Twenty-one adult Sprague-Dawley rats (11 male, 10 female) were trained to perform fixed consecutive number (FCN), incremental repeated acquisition (IRA), and progressive ratio (PR) tasks for a minimum of 15 months prior to receiving anesthesia. At 23 months of age, rats were exposed to 1.3% isoflurane or medical grade air for 2h. Initial results revealed that a 2h exposure to isoflurane had no effect on IRA, FCN, or PR performance. Thus, rats received 3 additional exposures to 1.3% isoflurane or medical grade air: 2, 4 and 6h exposures with 2 weeks elapsing before exposure two, 3 weeks elapsing between exposures two and three, and 2 weeks elapsing between exposures three and four. These additional exposures had no observable effects on performance of any operant task. These results suggest that single and repeated exposures to isoflurane do not impair the performance of aged rats in tasks designed to measure behavioral inhibition, learning, and motivation. This

  20. Water age, exposure time, and local flushing time in semi-enclosed, tidal basins with negligible freshwater inflow

    NASA Astrophysics Data System (ADS)

    Viero, Daniele Pietro; Defina, Andrea

    2016-04-01

    Within the framework of tidally flushed, semi-enclosed basins with negligible freshwater inflow, and under steady periodic flow conditions, three frequently used local transport time scales to quantify the efficiency of water renewal, namely water age, exposure time, and local flushing time are studied and compared to each other. In these environments, water renewal is strongly controlled by diffusion, and it is significantly affected by the return flow (i.e., the fraction of effluent water that returns into the basin on each flood tide). The definition of water age is here modified to account for the return flow, in analogy with exposure time and local flushing time. We consider approximate time scales, whose accuracy is analyzed, in order to overcome problems related to the size of the computational domain and to reduce the computational effort. A new approximate procedure is introduced to estimate water age, which is based on the water aging rate. Also, the concept of local flushing time as a relevant time scale is introduced. Under steady periodic conditions, we demonstrate that the local flushing time quantitatively corresponds to water age, and well approximates exposure time when the flow is dominated by diffusion. Since the effort required to compute water age and exposure time is greater than that required to compute the local flushing time, the present results can also have a practical interest in the assessment of water renewal efficiency of semi-enclosed water basins. The results of a modeling study, in which the lagoon of Venice is used as a benchmark, confirm the substantial quantitative equivalence between these three transport time scales in highly diffusive environments.

  1. Prevalence of lead exposure among age and sex cohorts of Canada geese

    USGS Publications Warehouse

    DeStefano, S.; Brand, C.J.; Rusch, D.H.

    1992-01-01

    We examined the prevalence of lead exposure from ingestion of waste lead shot among age and sex cohorts of Canada geese (Branta canadensis) on the breeding, migration, and wintering grounds of the Eastern Prairie Population. Blood samples from 6963 geese were assayed for lead concentration by atomic absorption spectrophotometry. On the breeding grounds, no goslings and < 1 % of adults showed evidence of recent exposure to lead shot (i.e., concentrations in the blood elevated above the threshold value of 0. 18 ppm lead). However, median background blood lead concentrations (i.e., blood samples with < 0.18 ppm lead) were higher in adults than goslings, indicating that exposure of adults to lead had occurred during previous seasons. Waste lead shot was available on the migration and wintering grounds, where a larger proportion of the blood samples from immatures (< 1 year old) than adults (> 1 year old) had lead concentrations greater-than-or-equal-to 0.18 ppm. Median background lead levels remained higher in adults than in immatures throughout fall and winter. We also found that more immature males than immature females had elevated lead concentrations. Higher rates of intake of food and grit (including shot) probably partially account for the higher prevalence of elevated lead concentrations in immature Canada geese.//Nous avons ??tudi?? l'importance des expositions au plomb par ingestion de plombs de chasse chez les diff??rentes cohortes (??ge et sexe) de Bernaches du Canada (Branta canadensis) dans les zones de reproduction et de migration et dans les territoires d'hiver chez la population de la Prairie de l'Est. Des ??chantillons de sang ont ??t?? pr??lev??s chez 6963 bernaches et analys??s au sphectrophotom??tre ? absorption atomique pour en d??terminer le contenu en plomb. Dans les zones de reproduction, les traces d'exposition r??cente ? des plombs (i.e. concentrations de plomb dans le sang au-dessus de la valeur seuil de 0,18 ppm) ??taient apparentes chez

  2. Brief dark exposure restored ocular dominance plasticity in aging mice and after a cortical stroke.

    PubMed

    Stodieck, Sophia Katharina; Greifzu, Franziska; Goetze, Bianka; Schmidt, Karl-Friedrich; Löwel, Siegrid

    2014-12-01

    In the primary visual cortex (V1), monocular deprivation (MD) induces a shift in the ocular dominance (OD) of binocular neurons towards the open eye (Wiesel and Hubel, 1963; Gordon and Stryker, 1996). In V1 of C57Bl/6J mice, this OD-plasticity is maximal in juveniles, declines in adults and is absent beyond postnatal day (PD) 110 (Lehmann and Löwel, 2008) if mice are raised in standard cages. Since it was recently shown that brief dark exposure (DE) restored OD-plasticity in young adult rats (PD70-100) (He et al., 2006), we wondered whether DE would restore OD-plasticity also in adult and old mice and after a cortical stroke. To this end, we raised mice in standard cages until adulthood and transferred them to a darkroom for 10-14 days. Using intrinsic signal optical imaging we demonstrate that short-term DE can restore OD-plasticity after MD in both adult (PD138) and old mice (PD535), and that OD-shifts were mediated by an increase of open eye responses in V1. Interestingly, restored OD-plasticity after DE was accompanied by a reduction of both parvalbumin expressing cells and perineuronal nets and was prevented by increasing intracortical inhibition with diazepam. DE also maintained OD-plasticity in adult mice (PD150) after a stroke in the primary somatosensory cortex. In contrast, short-term DE did not affect basic visual parameters as measured by optomotry. In conclusion, short-term DE was able to restore OD-plasticity in both adult and aging mice and even preserved plasticity after a cortical stroke, most likely mediated by reducing intracortical inhibition.

  3. Reactive and dissolved meteoric 10Be/9Be ratios in the Amazon basin

    NASA Astrophysics Data System (ADS)

    Wittmann, Hella; Dannhaus, Nadine; von Blanckenburg, Friedhelm; Bouchez, Julien; Suessenberger, Annette; Guyot, Jean-Loup; Maurice, Laurence; Filizola, Naziano; Gaillardet, Jerome; Christl, Marcus

    2014-05-01

    Recently, the ratio of the meteoric cosmogenic nuclide 10Be to stable 9Be has been established as a weathering and erosion proxy where meteoric 10Be/9Be ratios in reactive phases of secondary weathering products leached from detrital Amazonian river sediment were measured[1]. For this dataset, we derived a new 10Be-based mass balance, which compares the fluxes exported during erosion and weathering, Fout, calculated by the sum of [10Be]reac multiplied by gauging-derived sediment discharge and [10Be]dissmultiplied by water discharge, to the meteoric depositional flux Fin. This assessment allows evaluating the weathering state of the Amazon basin. Further, in order to assess equilibration of reactive phases in the water column, we measured (10Be/9Be)reac ratios leached from suspended sediments for two depth profiles of the Amazon (55m depth) and Madeira (12m depth) Rivers, their corresponding surface dissolved 10Be/9Be ratios, as well as dissolved ratios of smaller Amazon tributaries (Beni, Madre de Dios) to compare with published reactive ratios[1]. In these rivers, modest pH and salinity fluctuations help to constrain a 'simple' system that might however still be affected by seasonally changing isotopic compositions between water and suspended sediment[2] and seasonal fluctuations of TSS and TDS[3]. The 10Be-based mass balance shows that in Andean source areas Fout/Fin ≡1, indicating a balance between ingoing and exported flux, whereas in the Shield headwaters, Fout/Fin=0.3, indicating a combination of decay of 10Be during storage and little export of 10Be associated with particulate and dissolved loads. In central Amazonia, the export of 10Be decreases slightly relative to its atmospheric flux as evidenced by Fout/Fin=0.8 for the Amazon and Madeira Rivers. This value is interpreted as being close to steady state, but its modification could be due to additions of Shield-derived sediment to sediment carried in the main river[4]. Regarding the depth profiles, our

  4. Exploring ice core drilling chips from a cold Alpine glacier for cosmogenic radionuclide (10Be) analysis

    NASA Astrophysics Data System (ADS)

    Zipf, Lars; Merchel, Silke; Bohleber, Pascal; Rugel, Georg; Scharf, Andreas

    Ice cores offer unique multi-proxy paleoclimate records, but provide only very limited sample material, which has to be carefully distributed for various proxy analyses. Beryllium-10, for example, is analysed in polar ice cores to investigate past changes of the geomagnetic field, solar activity, and the aerosol cycle, as well as to more accurately date the material. This paper explores the suitability of a drilling by-product, the so-called drilling chips, for 10Be-analysis. An ice core recently drilled at a cold Alpine glacier is used to directly compare 10Be-data from ice core samples with corresponding drilling chips. Both sample types have been spiked with 9Be-carrier and identically treated to chemically isolate beryllium. The resulting BeO has been investigated by accelerator mass spectrometry (AMS) for 10Be/9Be-ratios to calculate 10Be-concentrations in the ice. As a promising first result, four out of five sample-combinations (ice core and drilling chips) agree within 2-sigma uncertainty range. However, further studies are needed in order to fully demonstrate the potential of drilling chips for 10Be-analysis in alpine and shallow polar ice cores.

  5. The effects of prenatal methamphetamine exposure on childhood growth patterns from birth to 3 years of age.

    PubMed

    Zabaneh, Rachel; Smith, Lynne M; LaGasse, Linda L; Derauf, Chris; Newman, Elana; Shah, Rizwan; Arria, Amelia; Huestis, Marilyn; Haning, William; Strauss, Arthur; Della Grotta, Sheri; Dansereau, Lynne M; Lin, Hai; Neal, Charles; Lester, Barry M

    2012-03-01

    We examined the effects of prenatal methamphetamine (MA) exposure on growth parameters from birth to age 3 years. The 412 subjects included (n = 204 exposed) were enrolled at birth in the Infant Development, Environment and Lifestyle study, a longitudinal study assessing the effects of prenatal MA exposure on childhood outcomes. Individual models were used to examine the effects of prenatal MA exposure on weight, head circumference, height, and weight-for-length growth trajectories. After adjusting for covariates, height trajectory was lower in the exposed versus the comparison children (p = 0.021) over the first 3 years of life. Both groups increased height on average by 2.27 cm per month by age 3 years. In term subjects, MA exposure was also associated with a lower height trajectory (p = 0.034), with both the exposed and comparison groups gaining 2.25 cm per month by age 3 years. There was no difference in weight, head circumference, or weight-for-length growth trajectories between the comparison and the exposed groups. Children exposed prenatally to MA have a modest decrease in height growth trajectory during the first 3 years of life with no observed difference in weight, head circumference, or weight-for-length trajectories.

  6. Dating of Holocene lateral moraines in the western Southern Alps, New Zealand, applying Schmidt-hammer exposure-age dating (SHD)

    NASA Astrophysics Data System (ADS)

    Winkler, Stefan

    2014-05-01

    Research on Holocene mountain glacier chronologies has recently intensified due to the importance of mountain glaciers as key indicators for past and present climate change. This progress is closely connected with major improvements in modern dating techniques and the application of multi-proxy approaches adapted to specific local/regional conditions. Despite recent progress there is, however, still a need for better spatial differentiation and a lack of generally accepted concepts for global and inter-hemispheric correlation of Holocene glacier chronologies. Furthermore, the "geomorphological uncertainty" inevitably connected with numerical dating of moraines in neotectonic active mountain ranges characterised by highly dynamic geomorphological process systems requires careful consideration of any subsequent palaeoclimatic interpretation. During the past few years Schmidt-hammer exposure-age dating (SHD) has revealed its potential to successfully challenge those specific circumstances. The Southern Alps of New Zealand have provided one of only a few suitable study sites for investigating Holocene glacier chronologies in the mid-latitudinal Southern Hemisphere. Recent years have seen a significant increase in terrestrial cosmogenic nuclide dating (TCND)-ages published for the Southern Alps, mainly for the last Glaciation, but also for the Holocene. The availability of a regional 10Be-production curve has improved the calibration of TCND-ages. These studies applying TCND alongside previous chronological studies using a variety of different dating techniques focus, however, primarily on a few selected glacier forelands east of the Main Divide in Aoraki/Mt Cook National Park. Bad accessibility and methodological problems account for comparatively few investigations on glacier forelands west of the Main Divide. Chronological studies applying Schmidt-hammer exposure-age dating (SHD) were performed on six glacier forelands in the western part of the Southern Alps

  7. Head impact exposure in youth football: elementary school ages 9-12 years and the effect of practice structure.

    PubMed

    Cobb, Bryan R; Urban, Jillian E; Davenport, Elizabeth M; Rowson, Steven; Duma, Stefan M; Maldjian, Joseph A; Whitlow, Christopher T; Powers, Alexander K; Stitzel, Joel D

    2013-12-01

    Head impact exposure in youth football has not been well-documented, despite children under the age of 14 accounting for 70% of all football players in the United States. The objective of this study was to quantify the head impact exposure of youth football players, age 9-12, for all practices and games over the course of single season. A total of 50 players (age = 11.0 ± 1.1 years) on three teams were equipped with helmet mounted accelerometer arrays, which monitored each impact players sustained during practices and games. During the season, 11,978 impacts were recorded for this age group. Players averaged 240 ± 147 impacts for the season with linear and rotational 95th percentile magnitudes of 43 ± 7 g and 2034 ± 361 rad/s(2). Overall, practice and game sessions involved similar impact frequencies and magnitudes. One of the three teams however, had substantially fewer impacts per practice and lower 95th percentile magnitudes in practices due to a concerted effort to limit contact in practices. The same team also participated in fewer practices, further reducing the number of impacts each player experienced in practice. Head impact exposures in games showed no statistical difference. While the acceleration magnitudes among 9-12 year old players tended to be lower than those reported for older players, some recorded high magnitude impacts were similar to those seen at the high school and college level. Head impact exposure in youth football may be appreciably reduced by limiting contact in practices. Further research is required to assess whether such a reduction in head impact exposure will result in a reduction in concussion incidence.

  8. Impact of low dose prenatal ethanol exposure on glucose homeostasis in Sprague-Dawley rats aged up to eight months.

    PubMed

    Probyn, Megan E; Parsonson, Kylie R; Gårdebjer, Emelie M; Ward, Leigh C; Wlodek, Mary E; Anderson, Stephen T; Moritz, Karen M

    2013-01-01

    Excessive exposure to alcohol prenatally has a myriad of detrimental effects on the health and well-being of the offspring. It is unknown whether chronic low-moderate exposure of alcohol prenatally has similar and lasting effects on the adult offspring's health. Using our recently developed Sprague-Dawley rat model of 6% chronic prenatal ethanol exposure, this study aimed to determine if this modest level of exposure adversely affects glucose homeostasis in male and female offspring aged up to eight months. Plasma glucose concentrations were measured in late fetal and postnatal life. The pancreas of 30 day old offspring was analysed for β-cell mass. Glucose handling and insulin action was measured at four months using an intraperitoneal glucose tolerance test and insulin challenge, respectively. Body composition and metabolic gene expression were measured at eight months. Despite normoglycaemia in ethanol consuming dams, ethanol-exposed fetuses were hypoglycaemic at embryonic day 20. Ethanol-exposed offspring were normoglycaemic and normoinsulinaemic under basal fasting conditions and had normal pancreatic β-cell mass at postnatal day 30. However, during a glucose tolerance test, male ethanol-exposed offspring were hyperinsulinaemic with increased first phase insulin secretion. Female ethanol-exposed offspring displayed enhanced glucose clearance during an insulin challenge. Body composition and hepatic, muscle and adipose tissue metabolic gene expression levels at eight months were not altered by prenatal ethanol exposure. Low-moderate chronic prenatal ethanol exposure has subtle, sex specific effects on glucose homeostasis in the young adult rat. As aging is associated with glucose dysregulation, further studies will clarify the long lasting effects of prenatal ethanol exposure.

  9. Study of 10 Be and 16 C cluster structure by means of breakup reactions

    NASA Astrophysics Data System (ADS)

    Dell'Aquila, D.

    2016-03-01

    The study of cluster structures in nuclei far from stability represents a valid tool to explore the nuclear force in few-body systems. In this paper we discuss a new experimental investigation of the structure of 10Be and 16C nuclei by means of projectile sequential break-up reactions induced on CH2 target at intermediate-energies. Their spectroscopy is obtained via a relative energy analysis of break-up fragments with the CHIMERA multi-detector. From 4He+6He correlations we suggest the presence of a new state at about 13.5MeV in 10Be. The inspection of 6He+10Be break-up channel reveals the existence of a possible high-lying excited state at 20.6MeV in 16C. Finally, new perspectives concerning the improvement of the present results are discussed.

  10. Prenatal and childhood polybrominated diphenyl ether (PBDE) exposure and attention and executive function at 9–12 years of age

    PubMed Central

    Sagiv, Sharon K.; Kogut, Katherine; Gaspar, Fraser; Gunier, Robert; Harley, Kim; Parra, Kimberly; Villaseñor, Diana; Bradman, Asa; Holland, Nina; Eskenazi, Brenda

    2015-01-01

    Objective California children’s exposures to polybrominated diphenyl ether flame retardants (PBDEs) are among the highest measured worldwide. We previously reported associations for prenatal and childhood PBDE exposures with decrements in attention, processing speed, fine motor coordination, and cognition in children at ages 5 and 7 years. Here, we investigate associations of PBDEs with attention and executive function at ages 9 to 12 years in the expanded CHAMACOS cohort. Methods We measured PBDEs in prenatal and child age 9 year serum samples for families enrolled in the study since pregnancy (“CHAM1”, N=321). In a subsequent cohort for which families were enrolled at child age 9 (“CHAM2”, N=301), we measured PBDEs in maternal and child samples collected at child age 9, and used predictive modeling to estimate prenatal exposure levels. We examined associations of measured and estimated PBDE concentrations on children’s attention and executive functioning at ages 9, 10½, and 12 years. Results Geometric means for prenatal and childhood ΣPBDE levels (sum of PBDE−47,−99,−100,−153) for the expanded CHAMACOS cohort were 26.3 and 63.2 ng/g lipid, respectively, and did not differ significantly between CHAM1 and CHAM2 families. We found consistent associations of prenatal exposure to PBDEs with poorer attention and executive function, measured with parent report and direct neuropsychological testing of the child. For example, using GEE models of repeated outcome measures at age 9 and 12, a 10-fold increase in prenatal ΣPBDE was associated with poorer response consistency on the Conners’ Continuous Performance Test II (β=2.9; 95% CI: 0.9, 4.8) and poorer working memory on the Behavioral Rating Inventory of Executive Function (β=2.5; 95% CI: 0.5, 4.4). Child age 9 ΣPBDE levels were associated with poorer parent-reported attention and executive function for girls but not boys. Conclusions Our results suggest that the prefrontal cortex may be a

  11. EVIDENCE FOR MULTIPLE SOURCES OF {sup 10}Be IN THE EARLY SOLAR SYSTEM

    SciTech Connect

    Wielandt, Daniel; Krot, Alexander N.; Bizzarro, Martin; Nagashima, Kazuhide; Huss, Gary R.; Ivanova, Marina A.

    2012-04-01

    Beryllium-10 is a short-lived radionuclide (t{sub 1/2} = 1.4 Myr) uniquely synthesized by spallation reactions and inferred to have been present when the solar system's oldest solids (calcium-aluminum-rich inclusions, CAIs) formed. Yet, the astrophysical site of {sup 10}Be nucleosynthesis is uncertain. We report Li-Be-B isotope measurements of CAIs from CV chondrites, including CAIs that formed with the canonical {sup 26}Al/{sup 27}Al ratio of {approx}5 Multiplication-Sign 10{sup -5} (canonical CAIs) and CAIs with Fractionation and Unidentified Nuclear isotope effects (FUN-CAIs) characterized by {sup 26}Al/{sup 27}Al ratios much lower than the canonical value. Our measurements demonstrate the presence of four distinct fossil {sup 10}Be/{sup 9}Be isochrons, lower in the FUN-CAIs than in the canonical CAIs, and variable within these classes. Given that FUN-CAI precursors escaped evaporation-recondensation prior to evaporative melting, we suggest that the {sup 10}Be/{sup 9}Be ratio recorded by FUN-CAIs represents a baseline level present in presolar material inherited from the protosolar molecular cloud, generated via enhanced trapping of galactic cosmic rays. The higher and possibly variable apparent {sup 10}Be/{sup 9}Be ratios of canonical CAIs reflect additional spallogenesis, either in the gaseous CAI-forming reservoir, or in the inclusions themselves: this indicates at least two nucleosynthetic sources of {sup 10}Be in the early solar system. The most promising locale for {sup 10}Be synthesis is close to the proto-Sun during its early mass-accreting stages, as these are thought to coincide with periods of intense particle irradiation occurring on timescales significantly shorter than the formation interval of canonical CAIs.

  12. Long-term erosion rates of Panamanian drainage basins determined using in situ 10Be

    NASA Astrophysics Data System (ADS)

    Gonzalez, Veronica Sosa; Bierman, Paul R.; Nichols, Kyle K.; Rood, Dylan H.

    2016-12-01

    Erosion rates of tropical landscapes are poorly known. Using measurements of in situ-produced 10Be in quartz extracted from river and landslide sediment samples, we calculate long-term erosion rates for many physiographic regions of Panama. We collected river sediment samples from a wide variety of watersheds (n = 35), and then quantified 24 landscape-scale variables (physiographic, climatic, seismic, geologic, and land-use proxies) for each watershed before determining the relationship between these variables and long-term erosion rates using linear regression, multiple regression, and analysis of variance (ANOVA). We also used grain-size-specific 10Be analysis to infer the effect of landslides on the concentration of 10Be in fluvial sediment and thus on erosion rates. Cosmogenic 10Be-inferred, background erosion rates in Panama range from 26 to 595 m My- 1, with an arithmetic average of 201 m My- 1, and an area-weighted average of 144 m My- 1. The strongest and most significant relationship in the dataset was between erosion rate and silicate weathering rate, the mass of material leaving the basin in solution. None of the topographic variables showed a significant relationship with erosion rate at the 95% significance level; we observed weak but significant correlation between erosion rates and several climatic variables related to precipitation and temperature. On average, erosion rates in Panama are higher than other cosmogenically-derived erosion rates in tropical climates including those from Puerto Rico, Madagascar, Australia and Sri Lanka, likely the result of Panama's active tectonic setting and thus high rates of seismicity and uplift. Contemporary sediment yield and cosmogenically-derived erosion rates for three of the rivers we studied are similar, suggesting that human activities are not increasing sediment yield above long-term erosion rate averages in Panama. 10Be concentration is inversely proportional to grain size in landslide and fluvial samples

  13. Effects of age on the disruption of cognitive performance by exposure to space radiation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Exposure to low doses of heavy particles and protons can cause deficits in cognitive performance when measured within a short time (1-4 months) following irradiation. The long-term effects of such exposures and their relationship to the short-term effects remain to be established. The present exp...

  14. Foetal Antiepileptic Drug Exposure and Verbal versus Non-Verbal Abilities at Three Years of Age

    ERIC Educational Resources Information Center

    Meador, Kimford J.; Baker, Gus A.; Browning, Nancy; Cohen, Morris J.; Clayton-Smith, Jill; Kalayjian, Laura A.; Kanner, Andres; Liporace, Joyce D.; Pennell, Page B.; Privitera, Michael; Loring, David W.

    2011-01-01

    We previously reported that foetal valproate exposure impairs intelligence quotient. In this follow-up investigation, we examined dose-related effects of foetal antiepileptic drug exposure on verbal and non-verbal cognitive measures. This investigation is an ongoing prospective observational multi-centre study in the USA and UK, which has enrolled…

  15. Enhanced taupathy and AD-like pathology in aged primate brains decades after infantile exposure to lead (Pb).

    PubMed

    Bihaqi, Syed Waseem; Zawia, Nasser H

    2013-12-01

    Late Onset Alzheimer Disease (LOAD) constitutes the majority of AD cases (∼90%). Amyloidosis and tau pathology, which are present in AD brains, appear to be sporadic in nature. We have previously shown that infantile lead (Pb) exposure is associated with a change in the expression and regulation of the amyloid precursor protein (APP) and its beta amyloid (Aβ) products in old age. Here we report that infantile Pb exposure elevated the mRNA and protein levels of tau as well as its transcriptional regulators namely specificity protein 1 and 3 (Sp1 and Sp3) in aged primates. These changes were also accompanied by an enhancement in site-specific tau phosphorylation as well as an increase in the mRNA and protein levels of cyclin dependent kinase 5 (cdk5). There was also a change in the protein ratio of p35/p25 with more Serine/Threonine phosphatase activity present in aged primates exposed to Pb as infants. These molecular alterations favored abundant tau phosphorylation and immunoreactivity in the frontal cortex of aged primates with prior Pb exposure. These findings provide more evidence that neurodegenerative diseases may be products of environmental influences that occur during the development.

  16. Elderly and sun-affected skin. Distinguishing between changes caused by aging and changes caused by habitual exposure to sun.

    PubMed Central

    Jackson, R.

    2001-01-01

    OBJECTIVE: To review and distinguish between skin changes produced by aging and changes produced by habitual exposure to sun. QUALITY OF EVIDENCE: The literature was searched from 1969 to 1999 for articles on dermatoheliosis and sun-damaged skin. Surprisingly few were found comparing the difference between elderly skin and sun-damaged skin. A few articles focused on certain small aspects of sun-damaged skin. Many excellent articles described particular changes (e.g., actinic keratosis), but few covered all the changes due to aging and to sun. MAIN MESSAGE: Skin changes due to aging can be distinguished from those due to sun damage. All changes due to sun exposure can be grouped under the term dermatoheliosis; five parts of the skin are involved: epidermis (actinic keratosis), dermis (solar elastosis), blood vessels (telangiectasia), sebaceous glands (solar comedones), and melanocytes (diffuse or mottled brown patches). Habitual exposure to sun and a white skin are prerequisites for developing these changes. Knowing the difference between changes caused by sun and by aging can help physicians predict which patients are most likely to get skin cancers. CONCLUSION: Knowledge of these common skin changes will help physicians diagnose and manage the skin abnormalities of elderly people and of people with dermatoheliosis. PMID:11421052

  17. Age at First Exposure to Football Is Associated with Altered Corpus Callosum White Matter Microstructure in Former Professional Football Players

    PubMed Central

    Stamm, Julie M.; Koerte, Inga K.; Muehlmann, Marc; Pasternak, Ofer; Bourlas, Alexandra P.; Baugh, Christine M.; Giwerc, Michelle Y.; Zhu, Anni; Coleman, Michael J.; Bouix, Sylvain; Fritts, Nathan G.; Martin, Brett M.; Chaisson, Christine; McClean, Michael D.; Lin, Alexander P.; Cantu, Robert C.; Tripodis, Yorghos; Shenton, Martha E.

    2015-01-01

    Abstract Youth football players may incur hundreds of repetitive head impacts (RHI) in one season. Our recent research suggests that exposure to RHI during a critical neurodevelopmental period prior to age 12 may lead to greater later-life mood, behavioral, and cognitive impairments. Here, we examine the relationship between age of first exposure (AFE) to RHI through tackle football and later-life corpus callosum (CC) microstructure using magnetic resonance diffusion tensor imaging (DTI). Forty retired National Football League (NFL) players, ages 40–65, were matched by age and divided into two groups based on their AFE to tackle football: before age 12 or at age 12 or older. Participants underwent DTI on a 3 Tesla Siemens (TIM-Verio) magnet. The whole CC and five subregions were defined and seeded using deterministic tractography. Dependent measures were fractional anisotropy (FA), trace, axial diffusivity, and radial diffusivity. Results showed that former NFL players in the AFE <12 group had significantly lower FA in anterior three CC regions and higher radial diffusivity in the most anterior CC region than those in the AFE ≥12 group. This is the first study to find a relationship between AFE to RHI and later-life CC microstructure. These results suggest that incurring RHI during critical periods of CC development may disrupt neurodevelopmental processes, including myelination, resulting in altered CC microstructure. PMID:26200068

  18. Increased Serum Insulin Exposure Does Not Affect Age or Stage of Pancreatic Adenocarcinoma Diagnosis in Patients with Diabetes Mellitus

    PubMed Central

    Chao, David T.; Shah, Nilesh H.; Zeh, Herbert J.; Bahary, Nathan; Whitcomb, David C.; Brand, Randall E.

    2015-01-01

    Objectives In considering whether medications that increase insulin levels accelerate pancreatic adenocarcinoma (PC) development, we hypothesized that PC patients with diabetes mellitus (DM) who used exogenous insulin or insulin-stimulating medications should have an earlier age of diagnosis or present with more advanced disease. Methods Patients enrolled in our PC registry from 6/1/2003 to 5/31/2012 were stratified according to treatment solely with insulin, insulin-stimulating medications, or insulin-independent medications. Age of PC diagnosis, PC stage, and years between DM and PC diagnoses were analyzed among the cohorts. Results Of 122 DM patients (mean age: 67.4 ± 10.2 years), the mean age of PC diagnosis within the insulin-only (n=40), insulin-stimulating (n=11), insulin-independent (n=71), and non-DM (n=321) cohorts were 68.7 ± 10.5 years, 69.6 ± 10.8 years, 66.3 ± 9.7 years, and 65.5 ± 10.5 years, respectively. No significant difference among the age of PC diagnosis was observed based on duration or type of DM treatment. There was no correlation between PC stage and increased insulin exposure. Conclusions Anti-DM medications that increase exposure to insulin do not appear to accelerate PC development using outcomes of mean age of PC diagnosis, PC stage, or duration between DM and PC diagnoses. PMID:26418902

  19. Age at First Exposure to Football Is Associated with Altered Corpus Callosum White Matter Microstructure in Former Professional Football Players.

    PubMed

    Stamm, Julie M; Koerte, Inga K; Muehlmann, Marc; Pasternak, Ofer; Bourlas, Alexandra P; Baugh, Christine M; Giwerc, Michelle Y; Zhu, Anni; Coleman, Michael J; Bouix, Sylvain; Fritts, Nathan G; Martin, Brett M; Chaisson, Christine; McClean, Michael D; Lin, Alexander P; Cantu, Robert C; Tripodis, Yorghos; Stern, Robert A; Shenton, Martha E

    2015-11-15

    Youth football players may incur hundreds of repetitive head impacts (RHI) in one season. Our recent research suggests that exposure to RHI during a critical neurodevelopmental period prior to age 12 may lead to greater later-life mood, behavioral, and cognitive impairments. Here, we examine the relationship between age of first exposure (AFE) to RHI through tackle football and later-life corpus callosum (CC) microstructure using magnetic resonance diffusion tensor imaging (DTI). Forty retired National Football League (NFL) players, ages 40-65, were matched by age and divided into two groups based on their AFE to tackle football: before age 12 or at age 12 or older. Participants underwent DTI on a 3 Tesla Siemens (TIM-Verio) magnet. The whole CC and five subregions were defined and seeded using deterministic tractography. Dependent measures were fractional anisotropy (FA), trace, axial diffusivity, and radial diffusivity. Results showed that former NFL players in the AFE <12 group had significantly lower FA in anterior three CC regions and higher radial diffusivity in the most anterior CC region than those in the AFE ≥12 group. This is the first study to find a relationship between AFE to RHI and later-life CC microstructure. These results suggest that incurring RHI during critical periods of CC development may disrupt neurodevelopmental processes, including myelination, resulting in altered CC microstructure.

  20. Quantifying Sub-Glacial Abrasion at Jakobshavn Isbræ: A Novel Approach Using In Situ 10Be Measurements

    NASA Astrophysics Data System (ADS)

    Young, N. E.; Briner, J. P.; Schaefer, J. M.

    2015-12-01

    Warm-based ice sheets and glaciers incontrovertibly erode and modify the terrain that they mantle; yet precise estimates of the rate and magnitude of sub-glacial erosion are rare. Estimates of sub-glacial erosion occurring beneath ice sheets, such as the Greenland Ice Sheet, are particularly important because they can provide key insights into sediment availability at ice-sheet margins that influences ice-sheet stability. Furthermore, estimates of sub-glacial erosion can help inform predictive geophysical ice-sheet models that incorporate a basal sliding parameter. Here, we take advantage of a detailed ice-margin history at Jakobshavn Isbræ over the last ~7,500 years, combined with in situ 10Be measurements from strategic bedrock locations, to quantify the rate of sub-glacial abrasion beneath Jakobshavn Isbræ's land-based margins. Our bedrock samples are from 1) locations that deglaciated ~7,500 years ago and have remained ice-free through present day, and 2) locations that also deglaciated ~7,500 years ago, but were re-occupied by the ice-margin during the last few hundred years. After accounting for the slightly different exposure histories between bedrock locations, and despite the short duration in ice-cover, initial 10Be measurements reveal a detectable difference in 10Be concentrations between the two bedrock surfaces. We hypothesize that the offset in 10Be concentrations reveals the magnitude of sub-glacial abrasion beneath Jakobshavn Isbræ's land-terminating margins.

  1. Prenatal methylmercury exposure and language delay at three years of age in the Norwegian Mother and Child Cohort Study.

    PubMed

    Vejrup, Kristine; Schjølberg, Synnve; Knutsen, Helle Katrine; Kvalem, Helen Engelstad; Brantsæter, Anne Lise; Meltzer, Helle Margrete; Alexander, Jan; Magnus, Per; Haugen, Margaretha

    2016-01-01

    Prenatal methylmercury (MeHg) exposure and its possible neurodevelopmental effects in susceptible children are of concern. Studies of MeHg exposure and negative health outcomes have shown conflicting results and it has been suggested that co-exposure to other contaminants and/or nutrients in fish may confound the effect of MeHg. Our objective was to examine the association between prenatal exposure to MeHg and language and communication development at three years, adjusting for intake of fish, n-3 long chain polyunsaturated fatty acids (n-3 LCPUFAs) and co-exposure to dioxins and dioxin like polychlorinated biphenyls (dl-PCBs). We used data from the Norwegian Mother and Child Cohort Study (MoBa) collected between 2002 and 2008. The study sample consisted of 46,750 mother-child pairs. MeHg exposure was calculated from reported fish intake during pregnancy by a FFQ in mid-pregnancy. Children's language and communication skills were measured by maternal report on the Dale and Bishop grammar rating and the Ages and Stages communication scale (ASQ). We estimated odds ratios (OR) and 95% confidence intervals (CI) using logistic regressions. Median MeHg exposure was 1.3μg/day, corresponding to 0.14μg/kgbw/week. An exposure level above the 90th percentile (>2.6μg/day, >0.29μg/kgbw/week) was defined as the high MeHg exposure. Results indicated an association between high MeHg exposure and unintelligible speech with an adjusted OR 2.22 (1.31, 3.72). High MeHg exposure was also associated with weaker communication skills adjusted OR 1.33 (1.03, 1.70). Additional adjustment for fish intake strengthened the associations, while adjusting for PCBs and n-3 LCPUFA from diet or from supplements had minor impact. In conclusion, significant associations were found between prenatal MeHg exposure above the 90th percentile and delayed language and communication skills in a generally low exposed population.

  2. English Language Learners' Nonword Repetition Performance: The Influence of Age, L2 Vocabulary Size, Length of L2 Exposure, and L1 Phonology

    ERIC Educational Resources Information Center

    Duncan, Tamara Sorenson; Paradis, Johanne

    2016-01-01

    Purpose: This study examined individual differences in English language learners' (ELLs) nonword repetition (NWR) accuracy, focusing on the effects of age, English vocabulary size, length of exposure to English, and first-language (L1) phonology. Method: Participants were 75 typically developing ELLs (mean age 5;8 [years;months]) whose exposure to…

  3. Infant and Early Childhood Exposure to Adult-Directed and Child-Directed Television Programming: Relations with Cognitive Skills at Age Four

    ERIC Educational Resources Information Center

    Barr, Rachel; Lauricella, Alexis; Zach, Elizabeth; Calvert, Sandra L.

    2010-01-01

    This study described the relations among the amount of child-directed versus adult-directed television exposure at ages 1 and 4 with cognitive outcomes at age 4. Sixty parents completed 24-hour television diaries when their children were 1 and 4 years of age. At age 4, their children also completed a series of cognitive measures and parents…

  4. 7Be and 10Be concentrations in recent firn and ice at Law Dome, Antarctica

    NASA Astrophysics Data System (ADS)

    Smith, A. M.; Fink, D.; Child, D.; Levchenko, V. A.; Morgan, V. I.; Curran, M.; Etheridge, D. M.; Elliott, G.

    2000-10-01

    Over the past three years, the Australian National Tandem for Applied Research (ANTARES) AMS facility at ANSTO has been expanding its sample preparation and measurement capability, particularly for 10Be, 26Al and 36Cl. During this time, ANSTO has continued its collaboration with the AAD and CSIRO Atmospheric Research on the measurement of cosmogenic isotopes from Law Dome, Antarctica. This research program has been supported by the construction of a dedicated geochemistry laboratory for the processing of ice and rock samples for the preparation of AMS targets. Here we present our first results for 10Be concentrations measured in ice cores from three sites at Law Dome and describe the sample processing protocol and aspects of the AMS measurement procedure. These sites are characterised by an eightfold difference in accumulation rate with a common precipitation source. In combination with an established ice chronology, this has enabled some preliminary findings concerning the relationship between the snow accumulation rate and the measured 10Be concentration for Law Dome during recent times. Additionally, we present 7Be and 10Be/ 7Be measurements made for a few surface snow samples from Law Dome and Australia.

  5. Constraints on the sedimentation history of San Francisco Bay from 14C and 10Be

    USGS Publications Warehouse

    VanGeen, A.; Valette-Silver, N. J.; Luoma, S.N.; Fuller, C.C.; Baskaran, M.; Tera, F.; Klein, J.

    1999-01-01

    Industrialization and urbanization around San Francisco Bay as well as mining and agriculture in the watersheds of the Sacramento and San Joaquin rivers have profoundly modified sedimentation patterns throughout the estuary. We provide some constraints on the onset of these erosional disturbances with 10Be data for three sediment cores: two from Richardson Bay, a small embayment near the mouth of San Francisco Bay, and one from San Pablo Bay, mid-way between the river delta and the mouth. Comparison of pre-disturbance sediment accumulation determined from three 14C-dated mollusk shells in one Richardson Bay core with more recent conditions determined from the distribution of 210Pb and 234Th [Fuller, C.C., van Geen, A., Baskaran, M, Anima, R.J., 1999. Sediment chronology in San Francisco Bay, California, defined by 210Pb, 234Th, 239,240Pu.] shows that the accumulation rate increased by an order of magnitude at this particular site. All three cores from San Francisco Bay show subsurface maxima in 10Be concentrations ranging in magnitude from 170 to 520 x 106 atoms/g. The transient nature of the increased 10Be input suggests that deforestation and agricultural develop- ment caused basin-wide erosion of surface soils enriched in 10Be. probably before the turn of the century.

  6. Dilute Nuclear States: {sup 12}C, {sup 10}Be and {sup 14}C

    SciTech Connect

    Freer, M.

    2008-11-11

    The experimental evidence for dilute {alpha}-particle states in {sup 12}C, {sup 10}Be and {sup 14}C is discussed. The question of the location of the 2{sup +} excitation of the 7.65 MeV {sup 12}C state remains unresolved, as does the existence of possible analogue states in {sup 14}C.

  7. 10Be climate fingerprints during the Eemian in the NEEM ice core, Greenland

    PubMed Central

    Sturevik-Storm, Anna; Aldahan, Ala; Possnert, Göran; Berggren, Ann-Marie; Muscheler, Raimund; Dahl-Jensen, Dorthe; Vinther, Bo M.; Usoskin, Ilya

    2014-01-01

    Several deep Greenland ice cores have been retrieved, however, capturing the Eemian period has been problematic due to stratigraphic disturbances in the ice. The new Greenland deep ice core from the NEEM site (77.45°N, 51.06°W, 2450 m.a.s.l) recovered a relatively complete Eemian record. Here we discuss the cosmogenic 10Be isotope record from this core. The results show Eemian average 10Be concentrations about 0.7 times lower than in the Holocene which suggests a warmer climate and approximately 65–90% higher precipitation in Northern Greenland compared to today. Effects of shorter solar variations on 10Be concentration are smoothed out due to coarse time resolution, but occurrence of a solar maximum at 115.26–115.36 kyr BP is proposed. Relatively high 10Be concentrations are found in the basal ice sections of the core which may originate from the glacial-interglacial transition and relate to a geomagnetic excursion about 200 kyr BP. PMID:25266953

  8. NQRS Data for C10H10Be (Subst. No. 1228)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C10H10Be (Subst. No. 1228)

  9. 10Be climate fingerprints during the Eemian in the NEEM ice core, Greenland

    NASA Astrophysics Data System (ADS)

    Sturevik-Storm, Anna; Aldahan, Ala; Possnert, Göran; Berggren, Ann-Marie; Muscheler, Raimund; Dahl-Jensen, Dorthe; Vinther, Bo M.; Usoskin, Ilya

    2014-09-01

    Several deep Greenland ice cores have been retrieved, however, capturing the Eemian period has been problematic due to stratigraphic disturbances in the ice. The new Greenland deep ice core from the NEEM site (77.45°N, 51.06°W, 2450 m.a.s.l) recovered a relatively complete Eemian record. Here we discuss the cosmogenic 10Be isotope record from this core. The results show Eemian average 10Be concentrations about 0.7 times lower than in the Holocene which suggests a warmer climate and approximately 65-90% higher precipitation in Northern Greenland compared to today. Effects of shorter solar variations on 10Be concentration are smoothed out due to coarse time resolution, but occurrence of a solar maximum at 115.26-115.36 kyr BP is proposed. Relatively high 10Be concentrations are found in the basal ice sections of the core which may originate from the glacial-interglacial transition and relate to a geomagnetic excursion about 200 kyr BP.

  10. 10Be climate fingerprints during the Eemian in the NEEM ice core, Greenland.

    PubMed

    Sturevik-Storm, Anna; Aldahan, Ala; Possnert, Göran; Berggren, Ann-Marie; Muscheler, Raimund; Dahl-Jensen, Dorthe; Vinther, Bo M; Usoskin, Ilya

    2014-09-30

    Several deep Greenland ice cores have been retrieved, however, capturing the Eemian period has been problematic due to stratigraphic disturbances in the ice. The new Greenland deep ice core from the NEEM site (77.45 °N, 51.06 °W, 2450 m.a.s.l) recovered a relatively complete Eemian record. Here we discuss the cosmogenic (10)Be isotope record from this core. The results show Eemian average (10)Be concentrations about 0.7 times lower than in the Holocene which suggests a warmer climate and approximately 65-90% higher precipitation in Northern Greenland compared to today. Effects of shorter solar variations on (10)Be concentration are smoothed out due to coarse time resolution, but occurrence of a solar maximum at 115.26-115.36 kyr BP is proposed. Relatively high (10)Be concentrations are found in the basal ice sections of the core which may originate from the glacial-interglacial transition and relate to a geomagnetic excursion about 200 kyr BP.

  11. 10Be history of cliff retreat: theory and example from the English Channel

    NASA Astrophysics Data System (ADS)

    Regard, Vincent; Dewez, Thomas; Bourlès, Didier; Duperret, Anne; Costa, Stéphane; Leanni, Laetitia; Lasseur, Eric; Pedoja, Kevin; Maillet, Grégoire

    2010-05-01

    What if coastal cliffs recession rates could be measured 60 times further in time than with classical methods? Coastal cliff evolution prediction for the next century would then not be so much of a stretch. In this work, we present a new method based on measurements and modelling of 10Be concentration transect across present-day shore platforms to establish the recession rate of coastal cliff for the last ca. 6000 years. The numerical model predicts the shape of 10Be concentration transects to be expected as a function of a given cliff recession rate, vertical coastal platform down-wearing rate and assumed time of sea level reestablishment to present-day level since deglaciation. Two independent transect features serve to fit long-term recession rate model to field observations: a major 10Be concentration drop is predicted where the cliff was abandoned for ca. 100k years, during the glacial period, and a characteristic dome shape directly related to the recession rate of the cliff. A retreating cliff site from the English Channel coast of France at Mesnil Val serves as a demonstrator of this method. Retreat rates were too fast to pinpoint the predicted glacial cliff position but 10Be concentrations sampled across the shore platform nevertheless indicate that the cliff retreat rate since the mid-late Holocene is comprised between 10-30 cm/yr, with a preferred value at 25 ± 5 cm, which turns out to be fully coherent with a 30-years-long assessment.

  12. Prenatal exposure to environmental contaminants and body composition at age 7–9 years

    SciTech Connect

    Delvaux, Immle; Van Cauwenberghe, Jolijn; Den Hond, Elly; Schoeters, Greet; Govarts, Eva; Nelen, Vera; Baeyens, Willy; Van Larebeke, Nicolas; Sioen, Isabelle

    2014-07-15

    The study aim was to investigate the association between prenatal exposure to endocrine disrupting chemicals (EDCs) and the body composition of 7 to 9 year old Flemish children. The subjects were 114 Flemish children (50% boys) that took part in the first Flemish Environment and Health Study (2002–2006). Cadmium, PCBs, dioxins, p,p′-DDE and HCB were analysed in cord blood/plasma. When the child reached 7–9 years, height, weight, waist circumference and skinfolds were measured. Significant associations between prenatal exposure to EDCs and indicators of body composition were only found in girls. After adjustment for confounders and covariates, a significant negative association was found in girls between prenatal cadmium exposure and weight, BMI and waist circumference (indicator of abdominal fat) and the sum of four skinfolds (indicator of subcutaneous fat). In contrast, a significant positive association (after adjustment for confounders/covariates) was found between prenatal p,p′-DDE exposure and waist circumference as well as waist/height ratio in girls (indicators of abdominal fat). No significant associations were found for prenatal PCBs, dioxins and HCB exposure after adjustment for confounders/covariates. This study suggests a positive association between prenatal p,p′-DDE exposure and indicators of abdominal fat and a negative association between prenatal cadmium exposure and indicators of both abdominal as well as subcutaneous fat in girls between 7 and 9 years old. - Highlights: • Associations between prenatal contaminant exposure and anthropometrics in children. • Significant association only found in girls. • No significant associations found for prenatal PCBs, dioxins and HCB exposure. • Girls: negative association between cadmium and abdominal and subcutaneous fat. • Girls: positive association between p,p′-DDE and indicators of abdominal fat.

  13. Regolith evolution on the millennial timescale from combined U-Th-Ra isotopes and in situ cosmogenic 10Be analysis in a weathering profile (Strengbach catchment, France)

    NASA Astrophysics Data System (ADS)

    Ackerer, J.; Chabaux, F.; Van der Woerd, J.; Viville, D.; Pelt, E.; Kali, E.; Lerouge, C.; Ackerer, P.; di Chiara Roupert, R.; Négrel, P.

    2016-11-01

    U-Th-Ra disequilibria, cosmogenic in situ 10Be concentrations and major and trace element concentrations have been analyzed in a 2 m-deep weathering profile sampled at the summit of the granitic Strengbach catchment (France). The data have been used to independently estimate both the long-term regolith production and denudation rates and the weathering and erosion rates. Modeling of the 238U-234U-230Th-226Ra disequilibrium variations in the lower part of the profile yields a regolith production rate of 12 ± 4 mm/kyr (30 ± 10 T/km2/yr), while modeling of the high-resolution 10Be concentration profile leads to an exposure age of 19.7 ± 2.2 kyr, an inherited concentration of 15,000 ± 1,000 at/g in quartz and a mean denudation rate of 22 ± 10 mm/kyr (37 ± 15 T/km2/yr). The consistency between production and denudation rates suggests that, on a millennial timescale, the regolith mass balance at the summit of the catchment is close to a steady state, even if the watershed may have been impacted by Quaternary climatic changes and by recent anthropogenic perturbations (e.g., 20th century acid rain and recent afforestation efforts). The results also indicate that physical erosion is likely the dominant long-term process of regolith denudation in the catchment. Furthermore, the comparison of the long-term production and denudation rates and of weathering and erosion rates determined from the depth profile analyses with the current weathering and erosion rates estimated at the outlet of the watershed based on monitoring of the water chemistry and sediment fluxes suggests that physical erosion may have varied more than the chemical weathering flux during the last 150 kyr. Although very few other sites with U-series, in situ 10Be and stream monitoring data are available for comparison, the current data suggest that (1) the mass balance steady state of regolith might be commonly achieved in soil mantled landscapes, and (2) physical erosion has varied much more than

  14. Cosmogenic Ne-21 exposure ages of glacial boulders constrained by local bedrock erosion rates in Ong Valley, Antarctica

    NASA Astrophysics Data System (ADS)

    Morgan, D. J.; Balco, G.; Putkonen, J.; Bibby, T.; Giusti, C.; Ball, A. E.; Hedberg, C. P.; Diamond, M. S.; Ringger, K. C.

    2013-12-01

    In order to accurately determine the exposure age of glacial boulders with cosmogenic nuclides, we need to know something about the erosion rate of the rock and any previous exposure the boulder may have had. Commonly, the erosion rate is simply assumed, and inheritance is dealt with by both sampling strategy and removing outliers from the data. In this study, we determine the rock erosion rate by measuring the concentration of cosmogenic Ne-21 in granite bedrock samples. This is used to constrain the exposure age of glacial boulders of the same lithology from the same locale. Ong Valley, Antarctica, (157.5 East, 83.25 South) is an ice-free valley in the Miller Range of the Central Transantarctic Mountains. The valley contains three distinct glacial drifts, and the oldest of these is well defined by an end moraine. We collected samples from six boulders on this end moraine, and six additional samples from the surrounding bedrock that is composed of the same lithology, the Hope Granite. The bedrock samples were collected from the ridge bordering the valley, well above the glacial limit. Because the bedrock samples have not been shielded by ice and have been exposed for millions of years, the concentration of cosmogenic Ne-21 in these samples reflects only the erosion rate of the granite. We separated quartz from the granite samples following standard laboratory methods and measured the concentration of cosmogenic Ne-21 in the quartz at the BGC Noble Gas Thermochronometry Lab. The concentration of cosmogenic Ne-21 in the bedrock samples is interpreted as reflecting only the erosion rate. We can then assume that the erosion rate of the bedrock is equal to the erosion rate of the glacial boulders on the end moraine because they have the same lithology and have been subjected to the same climate conditions during their exposure. With this information, we can better constrain the exposure age of the glacial boulders in Ong Valley.

  15. Plasma Efavirenz Exposure, Sex, and Age Predict Virological Response in HIV-Infected African Children

    PubMed Central

    Bienczak, Andrzej; Denti, Paolo; Cook, Adrian; Wiesner, Lubbe; Mulenga, Veronica; Kityo, Cissy; Kekitiinwa, Addy; Gibb, Diana M.; Burger, David; Walker, A. Sarah

    2016-01-01

    Background: Owing to insufficient evidence in children, target plasma concentrations of efavirenz are based on studies in adults. Our analysis aimed to evaluate the pediatric therapeutic thresholds and characterize the determinants of virological suppression in African children. Methods: We analyzed data from 128 African children (aged 1.7–13.5 years) treated with efavirenz, lamivudine, and one among abacavir, stavudine, or zidovudine, and followed up to 36 months. Individual pharmacokinetic (PK) measures [plasma concentration 12 hours after dose (C12h), plasma concentration 24 hours after dose (C24h), and area under the curve (AUC0-24)] were estimated using population PK modeling. Cox multiple failure regression and multivariable fractional polynomials were used to investigate the risks of unsuppressed viral load associated with efavirenz exposure and other factors among 106 initially treatment-naive children, and likelihood profiling was used to identify the most predictive PK thresholds. Results: The risk of viral load >100 copies per milliliter decreased by 42% for every 2-fold increase in efavirenz mid-dose concentration [95% confidence interval (CI): 23% to 57%; P < 0.001]. The most predictive PK thresholds for increased risk of unsuppressed viral load were C12h 1.12 mg/L [hazard ratio (HR): 6.14; 95% CI: 2.64 to 14.27], C24h 0.65 mg/L (HR: 6.57; 95% CI: 2.86 to 15.10), and AUC0-24 28 mg·h/L (HR: 5.77; 95% CI: 2.28 to 14.58). Children older than 8 years had a more than 10-fold increased risk of virological nonsuppression (P = 0.005); among children younger than 8 years, boys had a 5.31 times higher risk than girls (P = 0.007). Central nervous system adverse events were infrequently reported. Conclusions: Our analysis suggests that the minimum target C24h and AUC0-24 could be lowered in children. Our findings should be confirmed in a prospective pediatric trial. PMID:27116047

  16. Exposures to Endocrine-Disrupting Chemicals and Age of Menarche in Adolescent Girls in NHANES (2003–2008)

    PubMed Central

    Sircar, Kanta; Martin, Colleen

    2012-01-01

    Background: The observed age of menarche has fallen, which may have important adverse social and health consequences. Increased exposure to endocrine-disrupting compounds (EDCs) has been associated with adverse reproductive outcomes. Objective: Our objective was to assess the relationship between EDC exposure and the age of menarche in adolescent girls. Methods: We used data from female participants 12–16 years of age who had completed the reproductive health questionnaire and laboratory examination for the Centers for Disease Control and Prevention’s National Health and Nutrition Examination Survey (NHANES) for years 2003–2008 (2005–2008 for analyses of phthalates and parabens). Exposures were assessed based on creatinine-corrected natural log urine concentrations of selected environmental chemicals and metabolites found in at least 75% of samples in our study sample. We used Cox proportional hazards analysis in SAS 9.2 survey procedures to estimate associations after accounting for censored data among participants who had not reached menarche. We evaluated body mass index (BMI; kilograms per meter squared), family income-to-poverty ratio, race/ethnicity, mother’s smoking status during pregnancy, and birth weight as potential confounders. Results: The weighted mean age of menarche was 12.0 years of age. Among 440 girls with both reproductive health and laboratory data, after accounting for BMI and race/ethnicity, we found that 2,5-dichlorophenol (2,5-DCP) and summed environmental phenols (2,5-DCP and 2,4-DCP) were inversely associated with age of menarche [hazard ratios of 1.10; 95% confidence interval (CI): 1.01, 1.19 and 1.09; 95% CI: 1.01, 1.19, respectively]. Other exposures (total parabens, bisphenol A, triclosan, benzophenone-3, total phthalates, and 2,4-DCP) were not significantly associated with age of menarche. Conclusions: Our findings suggest an association between 2,5-DCP, a potential EDC, and earlier age of menarche in the general U

  17. Examination of age-related epigenetic changes following early-life exposure to dichloroacetic acid

    EPA Science Inventory

    Recent studies have shown that transient early-life exposure to dichloroacetic acid (DCA), a pyruvate analog and metabolic reprogramming agent, increases liver cancer incidence in older mice. This carcinogenic effect is not associated with direct mutagenicity, persistent cytotoxi...

  18. Headwall erosion rates from cosmogenic (10) Be in supraglacial debris, Chhota Shigri Glacier, Indian Himalaya

    NASA Astrophysics Data System (ADS)

    Scherler, Dirk; Egholm, David

    2016-04-01

    Debris-covered glaciers are widespread within the Himalaya and other steep mountain ranges. They testify to active erosion of ice-free bedrock hillslopes that tower above valley glaciers, sometimes more than 1 km high. It is long known that debris cover significantly reduces surface ablation rates and thereby influences glacial mass balances; but its dynamic evolution along with climatic and topographic changes is poorly studied. Better understanding the coupling of ice-free bedrock hillslopes and glaciers in steep mountains requires means to assess headwall erosion rates. Here, we present headwall erosion rates derived from 10Be concentrations in the ablation-dominated medial moraine of the Chhota Shigri Glacier, Indian Himalaya. We combine our empirical, field-based approach with a numerical model of headwall erosion and glacial debris transport to assess permissible patterns of headwall erosion on the ice-free bedrock hillslopes surrounding the Chhota Shigri Glacier. Our five samples, each separated by approximately 500 m along the glacier, consist of an amalgamation of >1000 surface clasts with grain sizes between ˜1 and ˜30 mm that were taken from the medial moraine. Our results show that 10Be concentrations increase downglacier from ˜3×104 to ˜6×104 atoms g-1, yielding headwall erosion rates of ˜1.3-0.6 mm yr-1. The accumulation of 10Be during debris residence on the ice surface can only account for a small fraction (<20%) of the downglacier increase. Other potential explanations include (1) heterogeneous source areas with differences average productions rates, and (2) homogeneous source areas but temporally variable headwall erosion rates. We use the 10Be-derived headwall erosion rates to define debris supply rates from ice-free bedrock hillslopes in the numerical ice model iSOSIA. Headwall debris that is deposited in the ablation zone of the ice surface becomes englacial, is passively advected with the ice and emerges in the ablation zone where it

  19. Small for gestational age and exposure to particulate air pollution in the early-life environment of twins.

    PubMed

    Bijnens, Esmée M; Derom, Catherine; Gielen, Marij; Winckelmans, Ellen; Fierens, Frans; Vlietinck, Robert; Zeegers, Maurice P; Nawrot, Tim S

    2016-07-01

    Several studies in singletons have shown that maternal exposure to ambient air pollutants is associated with restricted fetal growth. About half of twins have low birth weight compared with six percent in singletons. So far, no studies have investigated maternal air pollution exposure in association with birth weight and small for gestational age in twins. We examined 4760 twins of the East Flanders Prospective Twins Survey (2002-2013), to study the association between in utero exposure to air pollution with birth weight and small for gestational age. Maternal particulate air pollution (PM10) and nitric dioxide (NO2) exposure was estimated using a spatial temporal interpolation method over various time windows during pregnancy. In the total group of twins, we observed that higher PM10 and NO2 exposure during the third trimester was significantly associated with a lower birth weight and higher risk of small for gestational age. However, the association was driven by moderate to late preterm twins (32-36 weeks of gestation). In these twins born between 32 and 36 weeks of gestation, birth weight decreased by 40.2g (95% CI: -69.0 to -11.3; p=0.006) and by 27.3g (95% CI: -52.9 to -1.7; p=0.04) in association for each 10µg/m³ increment in PM10 and NO2 concentration during the third trimester. The corresponding odds ratio for small for gestational age were 1.68 (95% CI: 1.27-2.33; p=0.0003) and 1.51 (95% CI: 1.18-1.95; p=0.001) for PM10 or NO2, respectively. No associations between air pollution and birth weight or small for gestational age were observed among term born twins. Finally, in all twins, we found that for each 10µg/m³ increase in PM10 during the last month of pregnancy the within-pair birth weight difference increased by 19.6g (95% CI: 3.7-35.4; p=0.02). Assuming causality, an achievement of a 10µg/m³ decrease of particulate air pollution may account for a reduction by 40% in small for gestational age, in twins born moderate to late preterm.

  20. IMPROVING OUR UNDERSTANDING OF SUSCEPTIBILITY IN THE AGING POPULATION TO ENVIRONMENTAL EXPOSURES.

    EPA Science Inventory

    A radical demographic shift is taking place in America, with aging adults being the fastest-growing segment of the population. Considerable research is underway on the biology of aging and on remedies for treating the diseases of aging. Remarkably little is known, however, about ...

  1. 40Ar/39Ar and cosmic ray exposure ages of plagioclase-rich lithic fragments from Apollo 17 regolith, 78461

    NASA Astrophysics Data System (ADS)

    Das, J. P.; Baldwin, S. L.; Delano, J. W.

    2016-01-01

    Argon isotopic data is used to assess the potential of low-mass samples collected by sample return missions on planetary objects (e.g., Moon, Mars, asteroids), to reveal planetary surface processes. We report the first 40Ar/39Ar ages and 38Ar cosmic ray exposure (CRE) ages, determined for eleven submillimeter-sized (ranging from 0.06 to 1.2 mg) plagioclase-rich lithic fragments from Apollo 17 regolith sample 78461 collected at the base of the Sculptured Hills. Total fusion analysis was used to outgas argon from the lithic fragments. Three different approaches were used to determine 40Ar/39Ar ages and illustrate the sensitivity of age determination to the choice of trapped (40Ar/36Ar)t. 40Ar/39Ar ages range from ~4.0 to 4.4 Ga with one exception (Plag#10). Surface CRE ages, based on 38Ar, range from ~1 to 24 Ma. The relatively young CRE ages suggest recent re-working of the upper few centimeters of the regolith. The CRE ages may result from the effect of downslope movement of materials to the base of the Sculptured Hills from higher elevations. The apparent 40Ar/39Ar age for Plag#10 is >5 Ga and yielded the oldest CRE age (i.e., ~24 Ma). We interpret this data to indicate the presence of parentless 40Ar in Plag#10, originating in the lunar atmosphere and implanted in lunar regolith by solar wind. Based on a chemical mixing model, plagioclase compositions, and 40Ar/39Ar ages, we conclude that lithic fragments originated from Mg-suite of highland rocks, and none were derived from the mare region.

  2. Development of the NBS /sup 10/Be//sup 9/Be isotopic standard reference material

    SciTech Connect

    Inn, K.G.W.; Raman, S.; Coursey, B.M.; Fassett, J.D.; Walker, R.L.

    1987-04-01

    The National Bureau of Standards (NBS), in conjunction with the Oak Ridge National Laboratory (ORNL) and the Accelerator Mass Spectrometry (AMS) community, is in the process of developing a /sup 10/Be//sup 9/Be isotopic solution Standard Reference Material (SRM). The starting /sup 10/Be//sup 9/Be solution was provided by the ORNL after Secondary Ionization Mass Spectrometric characterization for isotopic concentration. The radioactivity purity of the ORNL Master solution was confirmed by gamma-ray spectrometry, then diluted at NBS with solutions made from zone-refined single-crystal beryllium metal and sub-boiling double-distilled hydrochloric acid. Four serial dilutions were necessary to achieve a final /sup 10/Be//sup 9/Be isotopic composition of approximately 3 x 10/sup -11/ (g/g). The accuracy of the dilutions was confirmed by liquid scintillation and AMS measurements. The isotopic composition of the ORNL Master solution was also confirmed at NBS by Resonant Ionization Mass Spectrometry. The isotopic composition of the final solution is being affirmed at the present time through international laboratory AMS measurements.

  3. Study of bound states in 10Be by one neutron removal reactions of 11Be

    NASA Astrophysics Data System (ADS)

    Johansen, Jacob G.; Bildstein, V.; Borge, M. J. G.; Cubero, M.; Diriken, J.; Elseviers, J.; Fraile, L. M.; Fynbo, H. O. U.; Gaffney, L. P.; Gernhäuser, R.; Jonson, B.; Koldste, G. T.; Konki, J.; Kröll, T.; Krücken, R.; Mücher, D.; Nilsson, T.; Nowak, K.; Pakarinen, J.; Pesudo, V.; Raabe, R.; Riisager, K.; Seidlitz, M.; Tengblad, O.; Törnqvist, H.; Voulot, D.; Warr, N.; Wimmer, K.; De Witte, H.

    2017-04-01

    The bound states of 10Be have been studied by removing single neutrons from 11Be nuclei. A 2.8 MeV u–1 beam of 11Be was produced at ISOLDE, CERN and directed on to both proton and deuteron targets inducing one-neutron removal reactions. Charged particles were detected to identify the two reaction channels (d, t) and (p, d), and the individual states in 10Be were identified by gamma detection. All bound states but one were populated and identified in the (d, t) reaction. The combination of REX-ISOLDE and MINIBALL allowed for a clean separation of the high-lying states in 10Be. This is the first time these states have been separated in a reaction experiment. Differential cross sections have been calculated for all the reaction channels and compared to DWBA calculations. Spectroscopic factors are derived and compared to values from the litterature. While the overall agreement between the spectrocopic factors is poor, the ratio between the ground state and the first excited state is in agreement with the previous measured ones. Furthermore, a significant population of the {2}2+ state is observed, which which may indicate the presence of multi-step processes at our beam energy.

  4. Environmental exposure to lead and children's intelligence at the age of seven years. The Port Pirie Cohort Study

    SciTech Connect

    Baghurst, P.A.; McMichael, A.J.; Wigg, N.R.; Vimpani, G.V.; Robertson, E.F.; Roberts, R.J.; Tong, S.L. )

    1992-10-29

    Exposure to lead in early childhood is thought to result in delayed neuropsychological development. As yet there is little longitudinal evidence to establish whether these effects persist into later childhood. The authors measured IQ scores in 494 seven-year-old children from the lead-smelting community of Port Pirie, Australia, in whom developmental deficits associated with elevated blood lead concentrations had already been reported at the ages of two and four years. Exposure to lead was estimated from the lead concentrations in maternal blood samples drawn antenatally and at delivery and from blood samples drawn from the children at birth (umbilical-cord blood), at the ages of 6 and 15 months and 2 years, and annually thereafter. Data relating to known covariates of child development were collected systematically for each child throughout the first seven years of life. The authors found inverse relations between IQ at the age of seven years and both antenatal and postnatal blood lead concentrations. After adjustment by multiple regression for sex, parents' level of education, maternal age at delivery, parents' smoking status, socioeconomic status, quality of the home environment, maternal IQ, birth weight, birth order, feeding method (breast, bottle, or both), duration of breast-feeding, and whether the child's natural parents were living together, the relation with lead exposure was still evident for postnatal blood samples, particularly within the age range of 15 months to 4 years. For an increase in blood lead concentration from 10 micrograms per deciliter (0.48 mumol per liter) to 30 micrograms per deciliter (1.45 mumol per liter), expressed as the average of the concentrations at 15 months and 2, 3, and 4 years, the estimated reduction in the IQ of the children was in the range of 4.4 points (95 percent confidence interval, 2.2 to 6.6) to 5.3 points (95 percent confidence interval, 2.8 to 7.8).

  5. Environmental enrichment improves age-related immune system impairment: long-term exposure since adulthood increases life span in mice.

    PubMed

    Arranz, Lorena; De Castro, Nuria M; Baeza, Isabel; Maté, Ianire; Viveros, Maria Paz; De la Fuente, Mónica

    2010-08-01

    Age-related changes in immunity have been shown to highly influence morbidity and mortality. The aim of the present work was to study the effects of environmental enrichment (EE) (8-16 weeks) on several functions and oxidative stress parameters of peritoneal leukocytes, previously described as health and longevity markers, in mice at different ages, namely adult (44 +/- 4 weeks), old (69 +/- 4 weeks), and very old (92 +/- 4 weeks). Mortality rates were monitored in control and enriched animals, and effects on survival of long-term exposure to EE until natural death were determined. The results showed that exposure to EE was efficient in improving the function (i.e., macrophage chemotaxis and phagocytosis, lymphocyte chemotaxis and proliferation, natural killer cell activity, interleukin-2 and tumor necrosis factor-alpha levels) and decreasing the oxidative-inflammatory stress (i.e., lowered oxidized glutathione content, xanthine oxidase activity, expression of Toll-like receptors 2 and 4 on CD4 and CD8 cells, and increased reduced glutathione and glutathione peroxidase and catalase activities) of immune cells. These positive effects of EE were especially remarkable in animals at older ages. Importantly, long-term exposure to EE from adult age and until natural death stands out as a useful strategy to extend longevity. Thus, the present work confirms the importance of maintaining active mental and/or physical activity aiming to improve quality of life in terms of immunity, and demonstrates that this active life must be initiated at early stages of the aging process and preserved until death to improve life span.

  6. Pleistocene uplift, climate and morphological segmentation of the Northern Chile coasts (24°S-32°S): Insights from cosmogenic 10Be dating of paleoshorelines

    NASA Astrophysics Data System (ADS)

    Martinod, Joseph; Regard, Vincent; Riquelme, Rodrigo; Aguilar, German; Guillaume, Benjamin; Carretier, Sébastien; Cortés-Aranda, Joaquín; Leanni, Laetitia; Hérail, Gérard

    2016-12-01

    We present new cosmogenic (10Be) exposure ages obtained on Pleistocene marine abrasion shore terraces of Northern Chile between 24°S and 32°S in order to evaluate the temporal and spatial variability of uplift rates along the coastal forearc. Both the dispersion of cosmogenic concentrations in samples from the same terrace and data obtained in vertical profiles show that onshore erosion rates, following emergence of paleoshorelines, approached 1 m/Myr. Therefore, minimum ages calculated without considering onshore erosion may be largely underestimated for Middle Pleistocene terraces. The elevation of the last interglacial (MIS-5) paleoshoreline is generally between 25 and 45 m amsl, suggesting that the entire coast of the study area has been uplifting during the Upper Pleistocene at rates approaching 0.3 mm/yr. Available ages for Middle Pleistocene terraces suggest similar uplift rates, except in the Altos de Talinay area where uplift may have been accelerated by the activity of the Puerto Aldea Fault. The maximum elevation of Pleistocene paleoshorelines is generally close to 250 m and there is no higher older Neogene marine sediment, which implies that uplift accelerated during the Pleistocene following a period of coastal stability or subsidence. We observe that the coastal morphology largely depends on the latitudinal climatic variability. North of 26.75°S, the coast is characterized by the presence of a high scarp associated with small and poorly preserved paleoshorelines at its foot. The existence of the coastal scarp in the northern part of the study area is permitted by the hyper-arid climate of the Atacama Desert. This particular morphology may explain why paleoshorelines evidencing coastal uplift are poorly preserved between 26.75°S and 24°S despite Upper Pleistocene uplift rates being comparable with those prevailing in the southern part of the study area.

  7. Detrital 10Be Response to the 2008 Wenchuan Earthquake and Quantifying Evacuation of Coseismic Landslide Debris

    NASA Astrophysics Data System (ADS)

    Wang, W.; Godard, V.; Liu-Zeng, J.; Scherler, D.; Xu, C.; Xu, Q.; Xie, K.; Bellier, O.; Bourles, D. L.; Ansberque, C.

    2014-12-01

    In reverse fault-bounded high relief mountain ranges, large-magnitude earthquakes contribute to the topographic growth by co- and inter-seismic surface uplift on the hanging wall. Meanwhile, they also trigger widespread landslides along ridge lines or hillslopes. Coseismic landsliding lowers relief and causes a phase of high erosion in the period following the quake. The net effect of large-magnitude earthquakes in topographic evolution of active orogens partially depends on how fast the landslide debris are being evacuated out of the mountain range. The 2008 Mw7.9 Wenchuan earthquake, China activated the Longmen Shan reverse fault system in eastern Tibetan plateau, also induced enormous amount of landslides, volume comparable to the coseismic uplift, providing an excellent opportunity to address the question. We use cosmogenic 10Be concentration in river sand as a tracer to study the sediment routing process of coseismic landslide debris, because landslide debris contains low 10Be concentration. We sampling annually during 2008-2013, at 19 locations along the rivers that traverse the fault ruptures, with upstream catchment area varying between 4.4 km2 and 21775 km2, including 10 catchments sampled before Wenchuan earthquake in 2004 and 2005. A comparison with pre-earthquake measurements show reduced 10Be concentration at all sites. This dilution is more significant for small catchments on short range-front rivers: mostly half to one-fourth, and down to one-fifth in some cases. Multi-year time series of 10Be concentration at single sites show roughly constant level of dilution six years after the quake, with moderate temporal fluctuations, which may be related to the variation in precipitation and storm intensity. Under the assumption of constant dilution rate and a depth-mixing of 10Be concentration for landslide input, a simple calculation indicates it would take ~ 200 to 3000 years to completely evacuate the landslides debris within range-front transverse rivers

  8. 40Ar-39Ar and cosmic-ray exposure ages of nakhlites—Nakhla, Lafayette, Governador Valadares—and Chassigny

    NASA Astrophysics Data System (ADS)

    Korochantseva, Ekaterina V.; Schwenzer, Susanne P.; Buikin, Alexei I.; Hopp, Jens; Ott, Ulrich; Trieloff, Mario

    2011-09-01

    Abstract- We present 40Ar-39Ar dating results of handpicked mineral separates and whole-rock samples of Nakhla, Lafayette, and Chassigny. Our data on Nakhla and Lafayette and recently reported ages for some nakhlites and Chassigny (Misawa et al. 2006; Park et al. 2009) point to formation ages of approximately 1.4 Ga rather than 1.3 Ga that is consistent with previous suggestions of close-in-time formation of nakhlites and Chassigny. In Lafayette mesostasis, we detected a secondary degassing event at approximately 1.1 Ga, which is not related to iddingsite formation. It may have been caused by a medium-grade thermal event resetting the mesostasis age but not influencing the K-Ar system of magmatic inclusions and the original igneous texture of this rock. Cosmic-ray exposure ages for these meteorites and for Governador Valadares were calculated from bulk rock concentrations of cosmogenic nuclides 3He, 21Ne, and 38Ar. Individual results are similar to literature data. The considerable scatter of T3, T21, and T38 ages is due to systematic uncertainties related to bulk rock and target element chemistry, production rates, and shielding effects. This hampers efforts to better constrain the hypothesis of a single ejection event for all nakhlites and Chassigny from a confined Martian surface terrain (Eugster 2003; Garrison and Bogard 2005). Cosmic-ray exposure ages from stepwise release age spectra using 38Ar and neutron induced 37Ar from Ca in irradiated samples can eliminate errors induced by bulk chemistry on production rates, although not from shielding conditions.

  9. Reconciling tectonic shortening, sedimentation and spatial patterns of erosion from 10Be paleo-erosion rates in the Argentine Precordillera

    NASA Astrophysics Data System (ADS)

    Val, Pedro; Hoke, Gregory D.; Fosdick, Julie C.; Wittmann, Hella

    2016-09-01

    The temporal evolution of erosion over million-year timescales is key to understand the development of mountain ranges and adjacent fold-and-thrust belts. While models of orogenic wedge dynamics predict an instantaneous response of erosion to pulses of rock uplift, stream-power based models predict that catchment-wide erosion maxima significantly lag behind a pulse of rock uplift. Here, we explore the relationships between rock uplift, erosion, and sediment deposition in the Argentine Precordillera fold-and-thrust belt at 30°S. Using a combination of 10Be-derived paleo-erosion rates, constraints on re-exposure using 26Al/10Be ratios, geomorphic observations and detrital zircon provenance, we demonstrate that the attainment of maximum upland erosion rates lags the maximum rate of deformation over million-year timescales. The magnitudes and causes of the erosional delays shed new light on the catchment erosional response to tectonic deformation and rock uplift in orogenic wedges.

  10. Cosmogenic exposure age evidence for rapid Laurentide deglaciation of the Katahdin area, west-central Maine, USA, 16 to 15 ka

    NASA Astrophysics Data System (ADS)

    Davis, P. Thompson; Bierman, Paul R.; Corbett, Lee B.; Finkel, Robert C.

    2015-05-01

    Katahdin, the highest peak in Maine and part of the second highest mountain range in New England, provides an opportunity to assess the timing and style of continental ice sheet surface lowering during deglaciation. We collected 14 samples from boulders on the adjacent Basin Ponds moraine, from bedrock and boulders on the upper part of the mountain, and from boulders in the surrounding area to estimate the age at which they were exposed by deglaciation of the Laurentide Ice Sheet. Measurements of in situ produced 10Be, which are consistent with measurements of 26Al, indicate that the Katahdin edifice became exposed from under ice by 15.3 ± 2.1 ka (n = 6), an age indistinguishable from the adjacent Basin Ponds moraine (16.1 ± 1.2 ka, n = 5). A boulder in the lowlands several km south of the moraine dates to 14.5 ± 0.8 ka, and a boulder deposited at Pineo Ridge, about 170 km SE of Katahdin, dates to 17.5 ± 1.1 ka. These data show that samples collected over an elevation range of 1.6 km and a distance of >170 km all have exposure ages that are indistinguishable within uncertainties. Together these data suggest that the Laurentide Ice Sheet surface dropped rapidly and the ice sheet margin retreated quickly across Maine between about 16 and 15 ka, perhaps influenced by calving of the marine-based ice sheet in the St. Lawrence Lowlands to the north and the Penobscot basin to the south.

  11. Millennial Rates of Sea Cliff Retreat Derived From Cosmogenic 10Be and Coastal Platform Morphology

    NASA Astrophysics Data System (ADS)

    Hurst, M. D.; Ellis, M. A.; Rood, D. H.

    2014-12-01

    Observation of cliff erosion are often limited to relatively short timescales (a few decades), which are within the timeframe of anthropogenic modification of the coast and may be shorter than the recurrence interval for erosion events. Here we present long-term (centennial-millennial) averaged rates of sea cliff retreat for chalk cliffs in SE England derived from cosmogenic isotopes and coastal morphology. We determine long-term rates of sea cliff erosion from 10Be measured from in situ flint samples collected from three transects across the coastal platform in East Sussex. A numerical model of 10Be accumulation on an evolving coastal profile allows estimation of cliff retreat rate averaged over several hundred years. The model accounts for variation in 10Be accumulation with tides and sea-level rise, and takes into account platform downwear and topographic shielding by adjacent cliffs. Additionally, we use high-resolution (1m) multibeam bathymetry to map the extent of the coastal platform based on the surface texture in order to infer the position of the coast at ~8 ka. The difference in position to the current coastline provides estimates of Holocene-averaged rates of cliff erosion for all chalk cliffed coastline in the region. Comparison to historic records of cliff retreat reveals key similarities and differences between long and short-term signals. In certain locations, there are significant discrepancies (either faster or slower) between historic records and long-term rates of retreat. Each type of discrepancy may be the result of human interaction with the coastal environment, whether that interaction is local or non-local, and it is worthwhile noting that sites of relatively low historic rates of erosion are likely subject to high-magnitude, low-frequency failure events that could have devastating effects on human lives and infrastructure in areas that are considered to be low risk.

  12. Exposure to Persistent Organic Pollutants Predicts Telomere Length in Older Age: Results from the Helsinki Birth Cohort Study

    PubMed Central

    Guzzardi, Maria Angela; Iozzo, Patricia; Salonen, Minna K.; Kajantie, Eero; Airaksinen, Riikka; Kiviranta, Hannu; Rantakokko, Panu; Eriksson, Johan Gunnar

    2016-01-01

    As the population ages, the occurrence of chronic pathologies becomes more common. Leukocyte telomere shortening associates to ageing and age-related diseases. Recent studies suggest that environmental chemicals can affect telomere length. Persistent organic pollutants (POPs) are most relevant, since they are ingested with foods, and accumulate in the body for a long time. This longitudinal study was undertaken to test if circulating POPs predict telomere length and shortening in elderly people. We studied 1082 subjects belonging to the Helsinki Birth Cohort Study (born 1934-1944), undergoing two visits (2001-2004 and 2011-2014). POPs (oxychlordane, trans-nonachlor, p, p’-DDE, PCB 153, BDE 47, BDE 153) were analysed at baseline. Relative telomere length was measured twice, ’10 years apart, by quantitative real-time PCR. Oxychlordane, trans-nonachlor and PCB-153 levels were significant predictors of telomere length and shortening. In men, we did not find a linear relationship between POPs exposure and telomere shortening. In women, a significant reduction across quartiles categories of oxychlordane and trans-nonachlor exposure was observed. Baseline characteristics of subjects in the highest POPs categories included higher levels of C-reactive protein and fasting glucose, and lower body fat percentage. This is one of few studies combining POPs and telomere length. Our results indicate that exposure to oxychlordane, trans-nonachlor and PCB 153 predicts telomere attrition. This finding is important because concentrations of POPs observed here occur in contemporary younger people, and may contribute to an accelerated ageing. PMID:27699078

  13. Chronic exposure to 50Hz magnetic fields causes a significant weakening of antioxidant defence systems in aged rat brain.

    PubMed

    Falone, Stefano; Mirabilio, Alessandro; Carbone, Maria Cristina; Zimmitti, Vincenzo; Di Loreto, Silvia; Mariggiò, Maria Addolorata; Mancinelli, Rosa; Di Ilio, Carmine; Amicarelli, Fernanda

    2008-01-01

    Several studies suggest that extremely low-frequency magnetic fields (ELF-MFs) may enhance the free radical endogenous production. It is also well known that one of the unavoidable consequences of ageing is an overall oxidative stress-based decline in several physiological functions and in the general resistance to stressors. On the basis of these assumptions, the aim of this study was to establish whether the ageing process can increase susceptibility towards widely present ELF-MF-mediated pro-oxidative challenges. To this end, female Sprague-Dawley rats were continuously exposed to a sinusoidal 50 Hz, 0.1 mT magnetic field for 10 days. Treatment-induced changes in the major antioxidant protection systems and in the neurotrophic support were investigated, as a function of the age of the subjects. All analyses were performed in brain cortices, due to the high susceptibility of neuronal cells to oxidative injury. Our results indicated that ELF-MF exposure significantly affects anti-oxidative capability, both in young and aged animals, although in opposite ways. Indeed, exposed young individuals enhanced their neurotrophic signalling and anti-oxidative enzymatic defence against a possible ELF-MF-mediated increase in oxygen radical species. In contrast, aged subjects were not capable of increasing their defences in response to ELF-MF treatment but, on the contrary, they underwent a significant decrease in the major antioxidant enzymatic activities. In conclusion, our data seem to suggest that the exposure to ELF-MFs may act as a risk factor for the occurrence of oxidative stress-based nervous system pathologies associated with ageing.

  14. Aging: Characteristics, Exposure Factors, Epigenetics, and Assessment of Health Risks of Older Adults

    EPA Science Inventory

    This chapter is organized into three sections. The first part describes the characteristics of the older adult population and the U.S. EPA’s efforts to protect elders form environmental hazards. Section II covers available exposure factor data, activity pattern and the pot...

  15. Early Childhood Household Smoke Exposure Predicts Less Task-Oriented Classroom Behavior at Age 10

    ERIC Educational Resources Information Center

    Pagani, Linda S.; Fitzpatrick, Caroline

    2016-01-01

    Secondhand tobacco smoke is considered a developmental neurotoxicant especially given underdeveloped vital systems in young children. An ecological test of its negative influence on brain development can be made by examining the prospective association between early childhood household smoke exposure and later classroom behavior. Using a…

  16. Prenatal Tobacco Exposure and Response Inhibition in School-Aged Children: An Event-Related Potential Study

    PubMed Central

    Boucher, Olivier; Jacobson, Joseph L.; Burden, Matthew J.; Dewailly, Éric; Jacobson, Sandra W.; Muckle, Gina

    2014-01-01

    Prenatal cigarette smoke exposure (PCSE) has been linked to problems in behavioral inhibition and attention deficit hyperactivity disorder in children in several epidemiological studies. We used event-related potentials (ERPs) to examine the effects of PCSE on neural correlates of inhibitory control of behavior. In a prospective longitudinal study on child development in the Canadian Arctic, we assessed 186 Inuit children (mean age = 11.3 years) on a visual Go/No-go response inhibition paradigm. PCSE was assessed through maternal recall. Potential confounders were documented from a maternal interview, and exposure to neurotoxic environmental contaminants was assessed from umbilical cord and child blood samples. PCSE was not related to behavioral performance on this simple response inhibition task. Nevertheless, this exposure was associated with smaller amplitudes of the N2 and P3 components elicited by No-go stimuli, suggesting an impairment in the neural processes underlying response inhibition. Amplitude of the No-go P3 component was also inversely associated with behavioral measures of externalizing problems and hyperactivity/impulsivity in the classroom. This study is the first to report neurophysiological evidence of impaired response inhibition in school-aged children exposed to tobacco smoke in utero. Effects were found on ERP components associated with conflict processing and inhibition of a prepotent response, indicating neurophysiological deficits that may play a critical role in the attention and behavior problems observed in children with PCSE. PMID:24946039

  17. No Association between Mycotoxin Exposure and Autism: A Pilot Case-Control Study in School-Aged Children

    PubMed Central

    Duringer, Jennifer; Fombonne, Eric; Craig, Morrie

    2016-01-01

    Evaluation of environmental risk factors in the development of autism spectrum disorder (ASD) is needed for a more complete understanding of disease etiology and best approaches for prevention, diagnosis, and treatment. A pilot experiment in 54 children (n = 25 ASD, n = 29 controls; aged 12.4 ± 3.9 years) screened for 87 urinary mycotoxins via liquid chromatography-tandem mass spectrometry to assess current exposure. Zearalenone, zearalenone-4-glucoside, 3-acetyldeoxynivalenol, and altenuene were detected in 9/54 (20%) samples, most near the limit of detection. No mycotoxin/group of mycotoxins was associated with ASD-diagnosed children. To identify potential correlates of mycotoxin presence in urine, we further compared the nine subjects where a urinary mycotoxin was confirmed to the remaining 45 participants and found no difference based on the presence or absence of mycotoxin for age (t-test; p = 0.322), gender (Fisher’s exact test; p = 0.456), exposure or not to selective serotonin reuptake inhibitors (Fisher’s exact test; p = 0.367), or to other medications (Fisher’s exact test; p = 1.00). While no positive association was found, more sophisticated sample preparation techniques and instrumentation, coupled with selectivity for a smaller group of mycotoxins, could improve sensitivity and detection. Further, broadening sampling to in utero (mothers) and newborn-toddler years would cover additional exposure windows. PMID:27447670

  18. 10Be measurements in bedrock constrain erosion beneath the Greenland Ice Sheet margin

    NASA Astrophysics Data System (ADS)

    Young, Nicolás. E.; Briner, Jason P.; Maurer, Josh; Schaefer, Joerg M.

    2016-11-01

    Glacial erosion is a key process driving landscape evolution, but it remains unclear what factors dictate the rate at which subglacial erosion occurs. Moreover, estimates of subglacial erosion that do not rely on sediment flux techniques are rare. Here, we present in situ 10Be measurements from bedrock surfaces in western Greenland with well-constrained ice-cover histories to quantify the erosion rate beneath the Greenland Ice Sheet margin during historical times. We calculate an abrasion rate of 0.72 ± 0.35 mm yr-1 and a likely total basin-wide erosion rate (abrasion + quarrying) of 1-1.8 mm yr-1, which are at least 1 order of magnitude higher than typical subglacial erosion rates in other polar landscapes. A compilation of published 10Be data suggests that the southwestern Greenland Ice Sheet acts as a particularly effective erosional agent within the broader Baffin Bay-Greenland region over millennial to glacial-interglacial timescales, suggestive of a basal ice sheet thermal regime controlled by regional climate.

  19. Studies of Be migration in the JET tokamak using AMS with 10Be marker

    NASA Astrophysics Data System (ADS)

    Bykov, I.; Bergsåker, H.; Possnert, G.; Zhou, Y.; Heinola, K.; Pettersson, J.; Conroy, S.; Likonen, J.; Petersson, P.; Widdowson, A.

    2016-03-01

    The JET tokamak is operated with beryllium limiter tiles in the main chamber and tungsten coated carbon fiber composite tiles and solid W tiles in the divertor. One important issue is how wall materials are migrating during plasma operation. To study beryllium redistribution in the main chamber and in the divertor, a 10Be enriched limiter tile was installed prior to plasma operations in 2011-2012. Methods to take surface samples have been developed, an abrasive method for bulk Be tiles in the main chamber, which permits reuse of the tiles, and leaching with hot HCl to remove all Be deposited at W coated surfaces in the divertor. Quantitative analysis of the total amount of Be in cm2 sized samples was made with inductively coupled plasma atomic emission spectroscopy (ICP-AES). The 10Be/9Be ratio in the samples was measured with accelerator mass spectrometry (AMS). The experimental setup and methods are described in detail, including sample preparation, measures to eliminate contributions in AMS from the 10B isobar, possible activation due to plasma generated neutrons and effects of diffusive isotope mixing. For the first time marker concentrations are measured in the divertor deposits. They are in the range 0.4-1.2% of the source concentration, with moderate poloidal variation.

  20. Prevalence and Associated Factors of Secondhand Smoke Exposure among Internal Chinese Migrant Women of Reproductive Age: Evidence from China's Labor-Force Dynamic Survey.

    PubMed

    Gong, Xiao; Luo, Xiaofeng; Ling, Li

    2016-04-01

    Secondhand smoke (SHS) is a major risk factor for poor health outcomes among women in China, where proportionately few women smoke. This is especially the case as it pertains to women's reproductive health, specifically migrant women who are exposed to SHS more than the population at large. There are several factors which may increase migrant women's risk of SHS exposure. This paper aims to investigate the prevalence and associated factors of SHS exposure among internal Chinese migrant women of reproductive age. The data used were derived from the 2014 Chinese Labor Dynamic Survey, a national representative panel survey. The age-adjusted rate of SHS exposure of women of reproductive age with migration experience was of 43.46% (95% CI: 40.73%-46.40%), higher than those without migration experience (35.28% (95% CI: 33.66%-36.97%)). Multivariate analysis showed that participants with a marital status of "Widowed" had statistically lower exposure rates, while those with a status of "Cohabitation" had statistically higher exposure. Those with an undergraduate degree or above had statistically lower SHS exposure. Those with increasing levels of social support, and those who currently smoke or drink alcohol, had statistically higher SHS exposure. Participants' different work-places had an effect on their SHS exposure, with outdoor workers statistically more exposed. Our findings suggest that urgent tobacco control measures should be taken to reduce smoking prevalence and SHS exposure. Specific attention should be paid to protecting migrant women of reproductive age from SHS.

  1. Reconstruction of Subdecadal Changes in Sunspot Numbers Based on the NGRIP 10Be Record

    NASA Astrophysics Data System (ADS)

    Inceoglu, F.; Knudsen, M. F.; Karoff, C.; Olsen, J.

    2014-11-01

    Sunspot observations since 1610 A.D. show that the solar magnetic activity displays long-term changes, from Maunder Minimum-like low-activity states to Modern Maximum-like high-activity episodes, as well as short-term variations, such as the pronounced 11-year periodicity. Information on changes in solar activity levels before 1610 relies on proxy records of solar activity stored in natural archives, such as 10Be in ice cores and 14C in tree rings. These cosmogenic radionuclides are produced by the interaction between Galactic cosmic rays (GCRs) and atoms in the Earth's atmosphere; their production rates are anti-correlated with the solar magnetic activity. The GCR intensity displays a distinct 11-year periodicity due to solar modulation of the GCRs in the heliosphere, which is inversely proportional to, but out of phase with, the 11-year solar cycle. This implies a time lag between the actual solar cycles and the GCR intensity, which is known as the hysteresis effect. In this study, we use the North Greenland Ice Core Project (NGRIP) records of the 10Be flux to reconstruct the solar modulation strength (Φ), which describes the modulation of GCRs throughout the heliosphere, to reconstruct both long-term and subdecadal changes in sunspot numbers (SSNs). We compare three different approaches for reconstructing subdecadal-scale changes in SSNs, including a linear approach and two approaches based on the hysteresis effect, i.e. models with ellipse-linear and ellipse relationships between Φ and SSNs. We find that the ellipse approach provides an amplitude-sensitive reconstruction and the highest cross-correlation coefficients in comparison with the ellipse-linear and linear approaches. The long-term trend in the reconstructed SSNs is computed using a physics-based model and agrees well with the other group SSN reconstructions. The new empirical approach, combining a physics-based model with ellipse-modeling of the 11-year cycle, therefore provides a method for

  2. Guidance on Selecting Age Groups for Monitoring and Assessing Childhood Exposures to Environmental Contaminants

    EPA Pesticide Factsheets

    This document recommends a set of age groupings based on current understanding of differences in lifestage behavior and anatomy and physiology that can serve as a starting set for consideration by Agency risk assessors and researchers.

  3. Port Pirie Cohort Study: environmental exposure to lead and children's abilities at the age of four years

    SciTech Connect

    McMichael, A.J.; Baghurst, P.A.; Wigg, N.R.; Vimpani, G.V.; Robertson, E.F.; Roberts, R.J.

    1988-08-25

    We studied the effect of environmental exposure to lead on children's abilities at the age of four years in a cohort of 537 children born during 1979 to 1982 to women living in a community situated near a lead smelter. Samples for measuring blood lead levels were obtained from the mothers antenatally, at delivery from the mothers and umbilical cords, and at the ages of 6, 15, and 24 months and then annually from the children. Concurrently, the mothers were interviewed about personal, family, medical, and environmental factors. Maternal intelligence, the home environment, and the children's mental development (as evaluated with use of the McCarthy Scales of Children's Abilities) were formally assessed. The mean blood lead concentration varied from 0.44 mumol per liter in midpregnancy to a peak of 1.03 mumol per liter at the age of two years. The blood lead concentration at each age, particularly at two and three years, and the integrated postnatal average concentration were inversely related to development at the age of four. Multivariate analysis incorporating many factors in the children's lives indicated that the subjects with an average postnatal blood lead concentration of 1.50 mumol per liter had a general cognitive score 7.2 points lower (95 percent confidence interval, 0.3 to 13.2; mean score, 107.1) than those with an average concentration of 0.50 mumol per liter. Similar deficits occurred in the perceptual-performance and memory scores. Within the range of exposure studied, no threshold dose for an effect of lead was evident. We conclude that postnatal blood lead concentration is inversely related to cognitive development in children, although one must be circumspect in making causal inferences from studies of this relation, because of the difficulties in defining and controlling confounding effects.

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  5. Tectonic control on 10Be-derived erosion rates in the Garhwal Himalaya, India

    NASA Astrophysics Data System (ADS)

    Scherler, Dirk; Bookhagen, Bodo; Strecker, Manfred R.

    2014-02-01

    Erosion in the Himalaya is responsible for one of the greatest mass redistributions on Earth and has fueled models of feedback loops between climate and tectonics. Although the general trends of erosion across the Himalaya are reasonably well known, the relative importance of factors controlling erosion is less well constrained. Here we present 25 10Be-derived catchment-averaged erosion rates from the Yamuna catchment in the Garhwal Himalaya, northern India. Tributary erosion rates range between ~0.1 and 0.5 mm yr-1 in the Lesser Himalaya and ~1 and 2 mm yr-1 in the High Himalaya, despite uniform hillslope angles. The erosion-rate data correlate with catchment-averaged values of 5 km radius relief, channel steepness indices, and specific stream power but to varying degrees of nonlinearity. Similar nonlinear relationships and coefficients of determination suggest that topographic steepness is the major control on the spatial variability of erosion and that twofold to threefold differences in annual runoff are of minor importance in this area. Instead, the spatial distribution of erosion in the study area is consistent with a tectonic model in which the rock uplift pattern is largely controlled by the shortening rate and the geometry of the Main Himalayan Thrust fault (MHT). Our data support a shallow dip of the MHT underneath the Lesser Himalaya, followed by a midcrustal ramp underneath the High Himalaya, as indicated by geophysical data. Finally, analysis of sample results from larger main stem rivers indicates significant variability of 10Be-derived erosion rates, possibly related to nonproportional sediment supply from different tributaries and incomplete mixing in main stem channels.

  6. Isovector and isoscalar dipole excitations in 9Be and 10Be studied with antisymmetrized molecular dynamics

    NASA Astrophysics Data System (ADS)

    Kanada-En'yo, Yoshiko

    2016-02-01

    Isovector and isoscalar dipole excitations in 9Be and 10Be are investigated in the framework of antisymmetrized molecular dynamics, in which angular-momentum and parity projections are performed. In the present method, 1p-1h excitation modes built on the ground state and a large amplitude α -cluster mode are taken into account. The isovector giant dipole resonance (GDR) in E >20 MeV shows the two-peak structure, which is understood from the dipole excitation in the 2 α core part with the prolate deformation. Because of valence neutron modes against the 2 α core, low-energy E 1 resonances appear in E <20 MeV, exhausting about 20 % of the Thomas-Reiche-Kuhn sum rule and 10 % of the calculated energy-weighted sum. The dipole resonance at E ˜15 MeV in 10Be can be interpreted as the parity partner of the ground state having a 6He+α structure and has remarkable E 1 strength because of the coherent contribution of two valence neutrons. The isoscalar dipole strength for some low-energy resonances is significantly enhanced by the coupling with the α -cluster mode. For the E 1 strength of 9Be, the calculation overestimates the energy-weighted sum (EWS) in the low-energy (E <20 MeV) and GDR (20

  7. Age-dependent dopaminergic dysfunction following fetal exposure to atrazine in SD rats.

    PubMed

    Li, Yanshu; Sun, Yan; Yang, Junwei; Wu, Yanping; Yu, Jia; Li, Baixiang

    2014-05-01

    The herbicide, atrazine (ATR), is used worldwide and its contamination in the environment has resulted in documented human exposure. It has also been shown that ATR results in dopaminergic neurotoxicity, however, few studies have investigated the long-term effects of ATR following in utero exposure. Therefore, we evaluated the effects of ATR exposure in Sprague Dawley rats during gestational on the offspring dopaminergic system development. Pregnant dams were treated with oral ATR at 0, 25, 50 mg/kg/day from gestational day 0 to postnatal day 1. In this study, we examined the hypothesis that ATR could cross the placental barrier and have long-term adverse effects on the synthesis, degradation and reuptake of DA in the brain. For this purpose,we examine the concentration of levodopa (L-DA), dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) in stratum. The mRNA and protein expression of orphan nuclear hormone (Nurr1), tyrosine hydroxylase(TH), vesicular monoaminetransporter 2 (VMAT2), dopamine transporter (DAT), monoamine (MAO), and catechol-O-methyl transferase (COMT) in the midbrain were examined by fluorescence PCR and Western blot when the offspring reached six-month old or one year old .When measured 6 months post-treatment, the level of DA and expression of Nurr1, VMAT2, DAT and TH were reduced in the striatum and Substantia nigra, respectively.

  8. In Utero and Childhood Polybrominated Diphenyl Ether Exposures and Body Mass at Age 7 Years: The CHAMACOS Study

    PubMed Central

    Erkin-Cakmak, Ayca; Harley, Kim G.; Chevrier, Jonathan; Bradman, Asa; Kogut, Katherine; Huen, Karen

    2015-01-01

    Background Polybrominated diphenyl ethers (PBDEs) are lipophilic flame retardants that bioaccumulate in humans. Child serum PBDE concentrations in California are among the highest worldwide. PBDEs may be associated with obesity by disrupting endocrine systems. Objective In this study, we examined whether pre- and postnatal exposure to the components of pentaBDE mixture was associated with childhood obesity in a population of Latino children participating in a longitudinal birth cohort study in the Salinas Valley, California. Methods We measured PBDEs in serum collected from 224 mothers during pregnancy and their children at 7 years of age, and examined associations with body mass index (BMI) at age 7 years. Results Maternal PBDE serum levels during pregnancy were associated with higher BMI z-scores in boys (BMI z-score βadjusted = 0.26; 95% CI: –0.19, 0.72) but lower scores in girls (BMI z-score βadjusted = –0.41; 95% CI: –0.87, –0.05) at 7 years of age (pinteraction = 0.04). In addition, child’s serum BDE-153 concentration (log10), but not other pentaBDE congeners, demonstrated inverse associations with BMI at age 7 years (BMI z-score βadjusted = –1.15; 95% CI: –1.53, –0.77), but there was no interaction by sex. Conclusions We estimated sex-specific associations with maternal PBDE levels during pregnancy and BMI at 7 years of age, finding positive associations in boys and negative associations in girls. Children’s serum BDE-153 concentrations were inversely associated with BMI at 7 years with no difference by sex. Future studies should examine the longitudinal trends in obesity with PBDE exposure and changes in hormonal environment as children transition through puberty, as well as evaluate the potential for reverse causality. Citation Erkin-Cakmak A, Harley KG, Chevrier J, Bradman A, Kogut K, Huen K, Eskenazi B. 2015. In utero and childhood polybrominated diphenyl ether exposures and body mass at age 7 years: the CHAMACOS Study. Environ

  9. Effects of moderate prenatal ethanol exposure and age on social behavior, spatial response perseveration errors and motor behavior.

    PubMed

    Hamilton, Derek A; Barto, Daniel; Rodriguez, Carlos I; Magcalas, Christy M; Fink, Brandi C; Rice, James P; Bird, Clark W; Davies, Suzy; Savage, Daniel D

    2014-08-01

    Persistent deficits in social behavior are among the major negative consequences associated with exposure to ethanol during prenatal development. Prior work from our laboratory has linked deficits in social behavior following moderate prenatal alcohol exposure (PAE) in the rat to functional alterations in the ventrolateral frontal cortex [21]. In addition to social behaviors, the regions comprising the ventrolateral frontal cortex are critical for diverse processes ranging from orofacial motor movements to flexible alteration of behavior in the face of changing consequences. The broader behavioral implications of altered ventrolateral frontal cortex function following moderate PAE have, however, not been examined. In the present study we evaluated the consequences of moderate PAE on social behavior, tongue protrusion, and flexibility in a variant of the Morris water task that required modification of a well-established spatial response. PAE rats displayed deficits in tongue protrusion, reduced flexibility in the spatial domain, increased wrestling, and decreased investigation, indicating that several behaviors associated with ventrolateral frontal cortex function are impaired following moderate PAE. A linear discriminant analysis revealed that measures of wrestling and tongue protrusion provided the best discrimination of PAE rats from saccharin-exposed control rats. We also evaluated all behaviors in young adult (4-5 months) or older (10-11 months) rats to address the persistence of behavioral deficits in adulthood and possible interactions between early ethanol exposure and advancing age. Behavioral deficits in each domain persisted well into adulthood (10-11 months), however, there was no evidence that aging enhances the effects of moderate PAE within the age ranges that were studied.

  10. Age- and sun exposure-dependent differences in 8-hydroxy-2'-deoxyguanosine and Nε-(carboxymethyl)lysine in human epidermis

    PubMed Central

    Toyokuni, Shinya; Hirao, Ayaka; Wada, Tamae; Nagai, Ryoji; Date, Akira; Yoshii, Takashi; Akatsuka, Shinya; Yamashita, Yoriko; Kawada, Akira

    2011-01-01

    Aging and exposure to sunlight are two major factors in the deterioration of skin function. In this study, thirty-six fixed human skin samples from sun-exposed and unexposed areas from young and old individuals were used to evaluate the localization of oxidative stress according to levels and distribution of 8-hydroxy-2'-deoxyguanosine and Nε-(carboxymethyl)lysine in samples using immunohistochemistry. In the epidermis of the young, negligible amounts of 8-hydroxy-2'-deoxyguanosine and Nε-(carboxymethyl)lysine were detected in unexposed areas, whereas nuclear 8-hydroxy-2'-deoxyguanosine and cytoplasmic Nε-(carboxymethyl)lysine were increased in the lower epidermis in sun-exposed areas. In contrast, the aged presented prominent nuclear 8-hydroxy-2'-deoxyguanosine and nuclear Nε-(carboxymethyl)lysine in the epidermis of unexposed areas, concomitant with dermal increase in Nε-(carboxymethyl)lysine. However, the immunostaining of 8-hydroxy-2'-deoxyguanosine and Nε-(carboxymethyl)lysine revealed a decrease in the epidermis of sun-exposed areas in the aged. These results suggest an age-dependent difference in the adaptation and protective mechanisms of the epidermis against sunlight-associated oxidative stress, thus necessitating distinct standards for evaluation in each age group. Further investigation is warranted to elucidate underlying molecular mechanisms. PMID:21980228

  11. Childhood Lead Exposure After the Phaseout of Leaded Gasoline: An Ecological Study of School-Age Children in Kampala, Uganda

    PubMed Central

    Graber, Lauren K.; Asher, Daniel; Anandaraja, Natasha; Bopp, Richard F.; Merrill, Karen; Cullen, Mark R.; Luboga, Samuel; Trasande, Leonardo

    2010-01-01

    Background Tetraethyl lead was phased out of gasoline in Uganda in 2005. Recent mitigation of an important source of lead exposure suggests examination and re-evaluation of the prevalence of childhood lead poisoning in this country. Ongoing concerns persist about exposure from the Kiteezi landfill in Kampala, the country’s capital. Objectives We determined blood lead distributions among Kampala schoolchildren and identified risk factors for elevated blood lead levels (EBLLs; ≥ 10 μg/dL). Analytical approach Using a stratified, cross-sectional design, we obtained blood samples, questionnaire data, and soil and dust samples from the homes and schools of 163 4- to 8-year-old children representing communities with different risks of exposure. Results The mean blood lead level (BLL) was 7.15 μg/dL; 20.5% of the children were found to have EBLL. Multivariable analysis found participants whose families owned fewer household items, ate canned food, or used the community water supply as their primary water source to have higher BLLs and likelihood of EBLLs. Distance < 0.5 mi from the landfill was the factor most strongly associated with increments in BLL (5.51 μg/dL, p < 0.0001) and likelihood of EBLL (OR = 4.71, p = 0.0093). Dust/soil lead was not significantly predictive of BLL/EBLL. Conclusions Lead poisoning remains highly prevalent among school-age children in Kampala. Confirmatory studies are needed, but further efforts are indicated to limit lead exposure from the landfill, whether through water contamination or through another mechanism. Although African nations are to be lauded for the removal of lead from gasoline, this study serves as a reminder that other sources of exposure to this potent neurotoxicant merit ongoing attention. PMID:20194080

  12. Prenatal Polycyclic Aromatic Hydrocarbon (PAH) Exposure, Antioxidant Levels and Behavioral Development of Children Ages 6–9

    PubMed Central

    Genkinger, Jeanine M.; Stigter, Laura; Jedrychowski, Wieslaw; Huang, Tzu-Jung; Wang, Shuang; Roen, Emily L.; Majewska, Renata; Kieltyka, Agnieszka; Mroz, Elzbieta; Perera, Frederica P.

    2015-01-01

    Purpose Prenatal polycyclic aromatic hydrocarbon (PAH) exposure has been shown to increase DNA adduct levels and to affect neurodevelopment. Micronutrients may modify the adverse effect of PAH on neurodevelopment. Thus, we examined if micronutrient concentrations modified the association between PAH exposure and neurodevelopmental outcomes. Methods 151 children from a birth cohort who had micronutrient concentrations measured in cord blood and completed the Child Behavioral Checklist (CBCL), between the ages of 6 and 9 years, were evaluated. Prenatal airborne PAH exposure was measured by personal air monitoring. The betas and 95% CI for the associations of antioxidant concentrations and PAH exposure with each of the outcomes of CBCL raw score and dichotomized standardized T-score (based on clinical cutpoints) were estimated, respectively, by multivariable poisson and logistic models. Results Children below the median for alpha-tocopherol and gamma-tocopherol concentrations, compared to those above, were more likely to have thought problems, aggressive behavior and externalizing problems (p<0.05). Lower carotenoid concentration was associated with more thought problems (MVβ=0.60, p<0.001) and externalizing problems (MVβ=0.13, p<0.05) for the same contrast. No statistically significant associations were observed between retinol concentrations and neurodevelopmental symptoms. Overall, no consistent patterns were observed when we examined the interaction between antioxidants (e.g., alpha-tocopherol) and PAH in relation to CBCL symptoms (e.g., internalizing and externalizing problems, p<0.05). Conclusions Lower alpha-tocopherol, gamma-tocopherol and carotenoid levels may adversely affect healthy neurodevelopment, even after accounting for PAH exposure. Future research to confirm these findings are warranted given the importance of identifying modifiable factors for reducing harmful PAH effects. PMID:25863187

  13. Prenatal Exposure to the Pesticide DDT and Hypertension Diagnosed in Women before Age 50: A Longitudinal Birth Cohort Study

    PubMed Central

    Cirillo, Piera M.; Terry, Mary Beth; Krigbaum, Nickilou Y.; Flom, Julie D.; Cohn, Barbara A.

    2013-01-01

    Background: Elevated levels of the pesticide DDT (dichlorodiphenyltrichloroethane) have been positively associated with blood pressure and hypertension in studies among adults. Accumulating epidemiologic and toxicologic evidence suggests that hypertension during adulthood may also be affected by earlier life and possibly the prenatal environment. Objectives: We assessed whether prenatal exposure to the pesticide DDT increases risk of adult hypertension. Methods: We examined concentrations of DDT (p,p´- and o,p´-) and its metabolite p,p´-DDE (dichlorodiphenyldichloroethylene) in prenatal serum samples from a subset of women (n = 527) who had participated in the prospective Child Health and Development Studies birth cohort in the San Francisco Bay area while they were pregnant between 1959 and 1967. We surveyed daughters 39–47 years of age by telephone interview from 2005 to 2008 to obtain information on self-reported physician-diagnosed hypertension and use of hypertensive medication. We used multivariable regression analysis of time to hypertension based on the Cox proportional hazards model to estimate relative rates for the association between prenatal DDT exposures and hypertension treated with medication in adulthood, with adjustment for potential confounding by maternal, early-life, and adult exposures. Results: Prenatal p,p´-DDT exposure was associated with hypertension [adjusted hazard ratio (aHR) = 3.6; 95% CI: 1.8, 7.2 and aHR = 2.5; 95% CI: 1.2, 5.3 for middle and high tertiles of p,p´-DDT relative to the lowest tertile, respectively]. These associations between p,p´-DDT and hypertension were robust to adjustment for independent hypertension risk factors as well as sensitivity analyses. Conclusions: These findings suggest that the association between DDT exposure and hypertension may have its origins early in development. PMID:23591545

  14. Fish oil and olive oil supplements attenuate the adverse cardiovascular effects of concentrated ambient air pollution particles exposure in healthy middle-aged adult human volunteers

    EPA Science Inventory

    Exposure to ambient levels of air pollution increases cardiovascular morbidity and mortality. Advanced age is among the factors associated with susceptibility to the adverse effects of air pollution. Dietary fatty acid supplementation has been shown to decrease cardiovascular ris...

  15. Effect of cell donor age on the cellular response to nanoparticle exposure

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Rafailovich, Miriam; Mironava, Tatsiana

    As human age there are many significant changes that occur in the skin. Here we investigate how the age-dependent changes in dermal fibroblast mechanics affect cell response to the AuNPs nanoparticles. To analyze these processes we exposed cells from donors of different age groups to AuNPs of two different sizes. Our results indicate that there are significant changes in cell rigidity with age, which in turn lead to different penetration rates of AuNPs through cell membrane and overall nanoparticle toxicity. Cell proliferation results revealed that all cell groups exposed to the same concentration of AuNPs had a very similar decrease in cell proliferation and similar impact on cell morphology. However, recovery data demonstrated that the rate of recovery from the damage is much faster for neonatal cells as compared to 30- and 80-years old cell group. Therefore, we conclude that nanoparticle uptake depends on cell membrane mechanics that in turn is a function of cell donor age.

  16. Pyrethroid insecticide exposure in school-aged children living in rice and aquacultural farming regions of Thailand

    PubMed Central

    Rohitrattana, Juthasiri; Siriwong, Wattasit; Robson, Mark; Panuwet, Parinya; Barr, Dana Boyd; Fiedler, Nancy

    2014-01-01

    Background Pyrethroid insecticides (PYR) are commonly used in rice farms and household pest control in Thailand. No investigative study has yet been made regarding factors associated with PYR exposure among Thai children. Objective This study aimed to compare the levels of PYR exposure between children living in rice farms (high-intensity PYR used) and aquacultural areas (low-intensity PYR used) during the wet and dry seasons in Thailand, during which different amounts of PYR are applied. Environmental conditions and common activities of children were used to identify factors associated with PYR exposure. Methods A cross-sectional study was done during the wet and dry seasons, respectively. A total of 53 participants aged between 6 and 8 years old were recruited from rice farms and aquacultural areas. A parental-structured interview was used to gather information about PYR use, household environments, and participants’ activities. First voided morning urine samples were collected for PYR urinary metabolites (ie, 3-phenoxybenzoic acid [3-PBA] and cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid [DCCA]) measurements. Hand wipe samples were collected during home visits, to measure PYR residues on the hands. Results and discussion The concentrations of urinary PYR metabolites were not significantly different between participants who lived in rice farming and those who lived in aquacultural areas, during both wet and dry seasons. Both participant groups had slightly increased urinary PYR metabolites during the wet season compared with the dry season. The results from linear regression analysis revealed that some environmental conditions and activities or practices may be used to predict trends of PYR exposure. Frequency of PYR use in farms (β=0.004) and households (β=0.07), proximity to rice farms (β=0.09), playing in rice farms (β=0.11), and oral exposure from objects exposed to PYR (β=0.08) were likely to be related to increased

  17. Impact of non-occupational exposure to polybrominated diphenyl ethers on menstruation characteristics of reproductive-age females.

    PubMed

    Chao, How-Ran; Shy, Cherng-Gueih; Wang, Shu-Li; Chen, Solomon Chih-Cheng; Koh, Teck-Wai; Chen, Fu-An; Chang-Chien, Gou-Ping; Tsou, Tsui-Chun

    2010-10-01

    Polybrominated diphenyl ethers (PBDEs) have documented effects on thyroid functions and rodent behavior in vivo. Epidemiological studies, however, have revealed only limited information about associations between PBDE exposure and menstruation characteristics. Our goal was to examine whether high breast milk PBDE levels in reproductive-age females lead to interference with menstruation characteristics. We analyzed 15 PBDE congeners in 46 breast milk samples. Fifteen PBDE congeners (BDE-15, 28, 47, 49, 99, 100, 153, 154, 183, 196, 197, 203, 207, 208, and 209) were analyzed using a gas chromatograph equipped with a high resolution mass spectrometer. The mean sum of PBDEs (SigmaPBDEs) in breast milk was 3.42 ng/g lipid. Women's age at menarche was not correlated with breast milk PBDE levels. Increased BDE-208 and 209 levels were significantly associated with the prolonged length of average and the longest menstrual cycle independent of age, pre-pregnant BMI, and parity. Higher concentrations of SigmaPBDEs and the higher brominated PBDEs from BDE-183 to 209, except 197, were significantly linked to women whose menstruation periods were still coming irregularly at the sampling time. Age-adjusted odds ratios (ORs) of BDE-153, 183, 207, 208, and SigmaPBDEs were significantly higher in women with length of average menstrual cycle >32 days, compared to the control. Women whose menstruation periods still came irregularly when they were 18 years old had higher age-adjusted ORs of BDE-207, 208, 209, and SigmaPBDEs than those whose periods came regularly at the same age. Although SigmaPBDEs and certain higher brominated PBDEs appear to have potential to prolong length of average menstrual cycle and delay the age when menstruation periods begin coming regularly, these findings are not conclusive because our sample size is small and more scientific evidence is needed.

  18. Age as a risk factor for the disruption of cognitive performance by exposure to the types of radiation encounted on exploratory class missions to other planets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Exposure to the types of radiation encountered in space (particles of high energy and charge [HZE particles]) produces changes in neurocognitive performance similar to those observed in the aged organism. As such, it is possible that there would be an interaction between the effects of exposure to ...

  19. 28 CFR 79.24 - Proof of initial or first exposure after age 20 for claims under § 79.22(b)(1).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Proof of initial or first exposure after age 20 for claims under § 79.22(b)(1). 79.24 Section 79.24 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) CLAIMS UNDER THE RADIATION EXPOSURE COMPENSATION ACT Eligibility Criteria for Claims Relating to Certain Specified...

  20. Fish consumption patterns and mercury exposure levels among women of childbearing age in Duval County, Florida.

    PubMed

    Traynor, Sharleen; Kearney, Greg; Olson, David; Hilliard, Aaron; Palcic, Jason; Pawlowicz, Marek

    2013-01-01

    Consumption of fish containing methylmercury can pose serious health concerns including neurotoxic effects in adults and toxicity to the fetuses of mothers exposed during pregnancy. In the study described in this article, the authors examined fish consumption patterns and measured hair mercury levels of women of childbearing age in a coastal county in Florida. Women from the community participated in a risk factor assessment survey (N = 703). Hair samples (n = 698) were collected and analyzed for mercury. The authors identified 74.8% below detection limit; 25.2% had detectable limits of mercury, while 7% exceeded 1 pg/g. Hair mercury levels increased with fish consumption and age. Race, income, and education levels were also associated with increased hair mercury levels. Women of Asian/Pacific Islander origin had the highest levels. Although reported fish consumption exceeded the recommendations for women of childbearing age, the study population had lower mercury levels than other comparative studies in Florida and at national levels.

  1. Further Investigations of Cosmogenic Ne-21 Exposure Ages of Glacial Boulders Constrained by Local Bedrock Erosion Rates in Ong Valley, Antarctica

    NASA Astrophysics Data System (ADS)

    Hedberg, C. P.; Morgan, D. J.; Cox, J.; Balco, G.; Putkonen, J.; Bibby, T.

    2014-12-01

    A history of glaciation can be tracked by determining the exposure age of boulders found in glacial drifts using the concentration of the cosmogenic nuclide Ne-21. In order to calculate exposure age, the erosion rate and previous exposure must be taken into consideration. In this study, we measured cosmogenic Ne-21 concentrations in quartz from samples of bedrock and samples taken from distinct glacial drifts in Antarctica. We determined the erosion rate using the concentrations of Ne-21 in the bedrock and then used this rate to calculate the exposure ages of the samples taken from the glacial drifts. The samples were collected from the Ong Valley, Antarctica (157.5 East, 83.25 South), an ice-free valley in the Miller Range of the Central Transantarctic Mountains that contains three distinct glacial drifts. We analyzed samples from the oldest and the youngest of these drifts, from moraines from a small alpine glacier to the east of the main valley, and from the surrounding bedrock of the valley walls above the glacial limit. The average erosion rate we calculated was 23 cm/Myrs. The six samples from the oldest glacial drift have an average exposure age of 2.1 Myrs, but have a range of 4.4 Myrs. The exposure age of samples from the middle of the youngest drift on the valley floor average 90.1 kyrs, with a range of 13.4 kyrs. Samples from a lateral moraine of this youngest drift have an average exposure age of 145 kyrs, with a range of 134 kyrs. The 7 samples taken from the alpine glacier east of Ong Valley have an average age of 1.10 Myrs, but a range of 3.87 Myrs. The high variability in ages among samples from the same glacial drift arises from prior exposure and postdepositional movement of the rocks.

  2. Prenatal Polybrominated Diphenyl Ether Exposures and Neurodevelopment in U.S. Children through 5 Years of Age: The HOME Study

    PubMed Central

    Yolton, Kimberly; Rauch, Stephen A.; Webster, Glenys M.; Hornung, Richard; Sjödin, Andreas; Dietrich, Kim N.; Lanphear, Bruce P.

    2014-01-01

    Background: Polybrominated diphenyl ethers (PBDEs) are persistent chemicals that have been widely used as flame retardants in furniture, carpet padding, car seats, and other consumer products during the past three decades. Objective: We examined whether in utero exposure to PBDEs is associated with child cognitive function and behavior in a U.S. study sample. Methods: In a prospective birth cohort, we measured maternal serum concentrations of BDE-47 and other PBDE congeners in 309 women at 16 weeks of gestation during 2003–2006 and followed their children in Cincinnati, Ohio. We measured cognitive and motor abilities using the Bayley Scales of Infant Development-II at ages 1, 2, and 3 years; intelligence using the Wechsler Preschool and Primary Scale of Intelligence-III at age 5 years; and children’s behaviors using the Behavioral Assessment System for Children-2 annually at ages 2–5 years. We used linear mixed models or generalized estimating equations with adjustment for potential confounders to estimate associations between these outcomes and log10-transformed PBDE concentrations. Results: The geometric mean of BDE-47 in maternal serum (20.1 ng/g lipid) was comparable with U.S. adult national reference values. Prenatal BDE-47 was not significantly associated with Bayley Mental or Psychomotor Development Indices at 1–3 years, but a 10-fold increase in prenatal BDE-47 was associated with a 4.5-point decrease (95% CI: –8.8, –0.1) in Full-Scale IQ and a 3.3-point increase (95% CI: 0.3, 6.3) in the hyperactivity score at age 5 years. Conclusions: Prenatal exposure to PBDEs was associated with lower IQ and higher hyperactivity scores in children. Citation: Chen A, Yolton K, Rauch SA, Webster GM, Hornung R, Sjödin A, Dietrich KN, Lanphear BP. 2014. Prenatal polybrominated diphenyl ether exposures and neurodevelopment in U.S. children through 5 years of age: the HOME study. Environ Health Perspect 122:856–862; http://dx.doi.org/10.1289/ehp.1307562 PMID

  3. Effect of age and social connection on perceived anxiety over radiation exposure among decontamination workers in Fukushima Prefecture, Japan

    PubMed Central

    Hidaka, Tomoo; Kakamu, Takeyasu; Hayakawa, Takehito; Kumagai, Tomohiro; Jinnouchi, Takanobu; Sato, Sei; Tsuji, Masayoshi; Nakano, Shinichi; Koyama, Kikuo; Fukushima, Tetsuhito

    2016-01-01

    Objectives: To reveal the effect of age and other factors on perceived anxiety over radiation exposure among decontamination workers in Fukushima Prefecture, Japan. Methods: A survey questionnaire was sent to 1505 workers, with questions regarding age, presence of a written employment contract, previous residence, radiation passbook ownership, presence of close persons for consultation, knowledge of how to access public assistance, and a four-point scale of radiation-related anxiety (1= "Very much," 2= "Somewhat," 3= "A little bit," and 4= "None" ). The relationships between the degree of anxiety and variables were analyzed using the chi-square test and residual analysis. Results: In all, 512 participants responded to the questionnaire. The mean age of participants was 46.2 years (SD: 13.1, range: 18-77). Of them, 50, 233, 168, and 61 workers chose "Very much," "Somewhat," "A little bit," and "None," respectively, on the anxiety scale. Chi-square test showed that participants aged 61 years and over had higher degrees of anxiety (p<0.001). Ordinal logistic regression showed that the degree of anxiety increased if they did not have a written contract (p=0.042) or persons to consult (p=0.034) and if they routinely checked the dose rate (p=0.046). Conclusions: Decontamination workers who do not have a written contract or who are in socially isolated situations have greater anxiety over radiation exposure. Thus, it is important to both create supportive human relationships for consultation and enhance labor management in individual companies. PMID:27010088

  4. Age as a determinant of phosphate flame retardant exposure of the Australian population and identification of novel urinary PFR metabolites.

    PubMed

    Van den Eede, Nele; Heffernan, Amy L; Aylward, Lesa L; Hobson, Peter; Neels, Hugo; Mueller, Jochen F; Covaci, Adrian

    2015-01-01

    The demand for alternative flame retardant materials such as phosphate flame retardants and plasticizers (PFRs) is increasing, although little is known of their possible effects on human health and development. To date, no information on the exposure of children or general Australian population to PFRs is available. The objectives of this study were to characterize the average levels and age-related patterns of PFR metabolites in urine in the general Australian population and to identify novel hydroxylated PFR metabolites in urine. Surplus pathology urine samples from Queensland, Australia were stratified and pooled by age and sex (3224 individuals aged 0 to 75years into 95 pools) according to two different pooling strategies at two different time periods. Samples were analyzed by solid phase extraction and liquid chromatography-tandem mass spectrometry following enzymatic treatment. Nine PFR metabolites were measured in the Australian population, including the first report of a hydroxylated metabolite of TCIPP (BCIPHIPP). Diphenyl phosphate (DPHP), BCIPHIPP and bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) were detected in >95% of samples. DPHP, a metabolite of aryl-PFRs, was found in several samples at levels which were one order of magnitude higher than previously reported (up to 730ng/mL). Weighted linear regression revealed a significant negative association between log-normalized BDCIPP and DPHP levels and age (p<0.001). Significantly greater levels of BDCIPP and DPHP were found in children's urine compared with adults, suggesting higher exposure to PFRs in young children. BCIPHIPP was identified for inclusion in future PFR biomonitoring studies.

  5. Morphogenetic evolution of the Têt river valley (eastern Pyrenees) using 10Be/21Ne cosmogenic burial dating

    NASA Astrophysics Data System (ADS)

    Sartégou, Amandine; Blard, Pierre-Henri; Braucher, Régis; Bourlès, Didier L.; Calvet, Marc; Zimmermann, Laurent; Tibari, Bouchaïb; Hez, Gabriel; Gunnell, Yanni; Aumaitre, Georges; Keddadouche, Karim

    2016-04-01

    The rates and chronologies of valley incision are closely modulated by the tectonic uplift of active mountain ranges and were controlled by repeated climate changes during the Quaternary. The continental collision between the Iberian and Eurasian plates induced a double vergence orogen, the Pyrenees, which has been considered as a mature mountain range in spite of significant seismicity (e.g. Chevrot et al., 2011) and evidence of neotectonics (e.g. Goula et al., 1999). Nevertheless, recent studies indicate that the range may have never reached a steady state (Ford et al., in press). One option for resolving this controversy is to quantify the incision rates since the Miocene by reconstructing the vertical movement of geometric markers such as fluvial terraces. However, the few available ages from the Pyrenean terrace systems do not exceed the middle Pleistocene. Thus, to enlarge the time span of this dataset, we studied alluvium-filled horizontal epiphreatic passages in limestone karstic networks. Such landforms are used as substitutes of fluvial terraces because they represent former valley floors (e.g. Palmer, 2007; Audra et al., 2013). They record the transient position of former local base levels during the process of valley deepening. The Têt river valley (southern Pyrenees) was studied near the Villefranche-de-Conflent limestone gorge where 8 cave levels have been recognized over a vertical height of 600 meters. Given that 26Al/10Be cosmogenic burial dating in this setting was limited to the last ~5 Ma (Calvet et al., 2015), here we used the cosmogenic 10Be/21Ne method in order to restore a more complete chronology of valley incision (e.g. Balco & Shuster, 2009; McPhilipps et al., 2016). Burial age results for alluvial deposits from 12 caves document incision rates since the Langhian (~14 Ma). Preliminary results indicate a history of valley deepening in successive stages. The data show a regular incision rate of 70-80 mm/a from the Langhian to the Messinian

  6. Cirques have growth spurts during deglacial and interglacial periods: Evidence from 10Be and 26Al nuclide inventories in the central and eastern Pyrenees

    NASA Astrophysics Data System (ADS)

    Crest, Y.; Delmas, M.; Braucher, R.; Gunnell, Y.; Calvet, M.

    2017-02-01

    Cirques are emblematic landforms of alpine landscapes. The statistical distribution of cirque-floor elevations is used to infer glacial equilibrium-line altitude, and the age of their frontal moraines for reconstructing glacial chronologies. Very few studies, however, have sought to measure cirque-floor and supraglacial ridgetop bedrock downwearing rates in order to confront these denudation estimates with theoretical models of Quaternary mountain landscape evolution. Here we use 10Be nuclide samples (n = 36) from moraines, bedrock steps, and supraglacial ridgetops among a population of cirques in the east-central Pyrenees in order to quantify denudation in the landscape and detect whether the mountain topography bears any relevance to the glacial buzzsaw hypothesis. Minimum exposure ages (MEAs) obtained for a succession of moraines spanning the Oldest Dryas to the Holocene produced a deglaciation chronology for three different Pyrenean ranges: Maladeta, Bassiès, and Carlit. Based on a series of corrections, calibrations, and chronostratigraphic tuning procedures, MEAs on ice-polished bedrock exposures were further used to model denudation depths at nested timescales during the Würm, the Younger Dryas, and the Holocene. Results show that subglacial cirque-floor denudation was lower during glacial periods (Würm: 10 mm/ka) than during deglacial and interglacial periods (tens to hundreds of mm/ka). The relative inefficiency of glacial denudation in the cirque zone during the Würm would have resulted from (i) cold-based and/or (ii) low-gradient glaciers situated in the upper reaches of the icefield; and/or from (iii) glacier-load starvation because of arrested clast supply from supraglacial rockslopes situated in the permafrost zone. Denudation peaked during the Younger Dryas and Holocene glacial advances, a time when cirque glaciers became steeper, warmer-based, and when frost cracking weakened supraglacial ridgetops, thus enhancing subglacial erosion by providing

  7. Effects of pre-natal alcohol exposure on hippocampal synaptic plasticity: Sex, age and methodological considerations.

    PubMed

    Fontaine, Christine J; Patten, Anna R; Sickmann, Helle M; Helfer, Jennifer L; Christie, Brian R

    2016-05-01

    The consumption of alcohol during gestation is detrimental to the developing central nervous system (CNS). The severity of structural and functional brain alterations associated with alcohol intake depends on many factors including the timing and duration of alcohol consumption. The hippocampal formation, a brain region implicated in learning and memory, is highly susceptible to the effects of developmental alcohol exposure. Some of the observed effects of alcohol on learning and memory may be due to changes at the synaptic level, as this teratogen has been repeatedly shown to interfere with hippocampal synaptic plasticity. At the molecular level alcohol interferes with receptor proteins and can disrupt hormones that are important for neuronal signaling and synaptic plasticity. In this review we examine the consequences of prenatal and early postnatal alcohol exposure on hippocampal synaptic plasticity and highlight the numerous factors that can modulate the effects of alcohol. We also discuss some potential mechanisms responsible for these changes as well as emerging therapeutic avenues that are beginning to be explored.

  8. Response of different-aged black cherry trees to ambient ozone exposure

    SciTech Connect

    Fredericksen, T.S.; Joyce, B.J.; Kouterick, K.B.; Kolb, T.E.; Skelly, J.M.; Steiner, K.C.; Savage, J.E.; Snyder, K.R. )

    1994-06-01

    Black cherry (Prunus serotina Ehrh.) is a valuable commercial timber species which is also highly sensitive to ozone relative to other eastern deciduous tree species. Studies of ozone effects on forest trees have been restricted mostly to experiments using small seedlings under controlled conditions. Yet, mature trees may differ from seedlings in physiology, morphology, and exposure to air pollutants. An experiment was conducted in 1993 to determine differences in ozone uptake and foliar injury symptoms between open-ground seedlings, forest saplings, and mature forest trees of black cherry in northcentral Pennsylvania. Seedlings grew under the highest ozone concentrations and also had greater seasonal ozone uptake due to higher rates of stomatal conductance. However, because of their indeterminate growth habit, seedlings had lower cumulative ozone uptake per leaf lifespan than saplings or mature trees, both of which had determinate shoot growth. Although greater initially for seedlings, foliar injury was nearly identical between size classes by the end of the growing season. Leaves in the lower crown of larger trees had lower ozone uptake than leaves in the upper crown, but exhibited more foliar injury symptoms. Lower crown leaves received more effective exposure to ozone because of their thinner leaves and had less available photosynthate for repair or replacement of damaged tissue.

  9. Playing-Related Musculoskeletal Problems in Child Instrumentalists: The Influence of Gender, Age and Instrument Exposure

    ERIC Educational Resources Information Center

    Ranelli, Sonia; Smith, Anne; Straker, Leon

    2011-01-01

    Playing-related musculoskeletal problems (PRMP) are common in adult musicians. The limited available evidence suggests PRMP are common in children and adolescents and that risk factors may be similar. The aim of this study was to determine the prevalence of PRMP in children and adolescents and their associations with female gender, age and…

  10. Ultrafine particles and black carbon personal exposures in asthmatic and non-asthmatic children at school-age.

    PubMed

    Pañella, Pau; Casas, Maribel; Donaire-Gonzalez, David; Garcia-Esteban, Raquel; Robinson, Oliver; Valentín, Antònia; Gulliver, John; Momas, Isabelle; Nieuwenhuijsen, Mark; Vrijheid, Martine; Sunyer, Jordi

    2017-03-20

    Traffic-related air pollution (TRAP) exposure during childhood is associated with asthma; however, the contribution of the different TRAP pollutants in each microenvironment (home, school, transportation, others) in asthmatic and non-asthmatic children is unknown. Daily (24 h) personal black carbon (BC), ultrafine particles (UFP), and alveolar lung deposited surface area (LDSA) individual exposure measurements were obtained from 100 children (29 past and 21 current asthmatics, 50 non-asthmatics) aged 9±0.7 years from the INMA-Sabadell cohort (Catalonia, Spain). Time spent in each microenvironment was derived by the geolocation provided by the smartphone and a new spatiotemporal map-matching algorithm. Asthmatics and non-asthmatics spent the same amount of time at home (60% and 61%, respectively), at school (20%, 23%), on transportation (8%, 7%), and in other microenvironments (7%, 5%). The highest concentrations of all TRAPs were attributed to transportation. No differences in TRAP concentrations were found overall or by type of microenvironment between asthmatics and non-asthmatics, nor when considering past and current asthmatics, separately. In conclusion, asthmatic and non-asthmatic children had a similar time activity pattern and similar average exposures to BC, UFP and LDSA concentrations. This suggests that interventions should be tailored to general population, rather than to subgroups defined by disease. This article is protected by copyright. All rights reserved.

  11. Cholinergic transmission during nicotine withdrawal is influenced by age and pre-exposure to nicotine: Implications for teenage smoking

    PubMed Central

    Carcoba, Luis M.; Orfila, James E.; Natividad, Luis A.; Torres, Oscar V.; Pipkin, Joseph A.; Ferree, Patrick L.; Castañeda, Eddie; Moss, Donald E.; O’Dell, Laura E.

    2014-01-01

    the NAcc were increased in a similar manner in adolescent versus adult rats. However, the increase in ACh that was observed in adult rats experiencing nicotine withdrawal was blunted in pre-exposed adults. These neurochemical effects do not appear to be related to nicotine metabolism, as plasma cotinine levels were similar across all groups. The second study revealed that nicotine exposure increased AChE activity in the NAcc to a greater extent in adolescent versus adult rats. There was no difference in AChE activity in pre-exposed versus naïve adult rats. In conclusion, our results suggest that nicotine exposure during adolescence enhances baseline ACh in the NAcc. However, the finding that ACh levels were similar during withdrawal in adolescent and adult rats suggests that the enhanced vulnerability to tobacco use during adolescence is not likely related to age differences in withdrawal-induced increases in cholinergic transmission. Our results also suggest that exposure to nicotine during adolescence suppresses withdrawal-induced increases in cholinergic responses during withdrawal. Taken together, this report illustrates important short- and long-term changes within cholinergic systems that may contribute to the enhanced susceptibility to tobacco use during adolescence. PMID:24854235

  12. Cholinergic transmission during nicotine withdrawal is influenced by age and pre-exposure to nicotine: implications for teenage smoking.

    PubMed

    Carcoba, Luis M; Orfila, James E; Natividad, Luis A; Torres, Oscar V; Pipkin, Joseph A; Ferree, Patrick L; Castañeda, Eddie; Moss, Donald E; O'Dell, Laura E

    2014-01-01

    nicotine withdrawal, ACh levels in the NAc were increased in a similar manner in adolescent versus adult rats. However, the increase in ACh that was observed in adult rats experiencing nicotine withdrawal was blunted in pre-exposed adults. These neurochemical effects do not appear to be related to nicotine metabolism, as plasma cotinine levels were similar across all groups. The second study revealed that nicotine exposure increased AChE activity in the NAc to a greater extent in adolescent versus adult rats. There was no difference in AChE activity in pre-exposed versus naïve adult rats. In conclusion, our results suggest that nicotine exposure during adolescence enhances baseline ACh in the NAc. However, the finding that ACh levels were similar during withdrawal in adolescent and adult rats suggests that the enhanced vulnerability to tobacco use during adolescence is not related to age differences in withdrawal-induced increases in cholinergic transmission. Our results also suggest that exposure to nicotine during adolescence suppresses withdrawal-induced increases in cholinergic responses during withdrawal. Taken together, this report illustrates important short- and long-term changes within cholinergic systems that may contribute to the enhanced susceptibility to tobacco use during adolescence.

  13. The Microstructural Evolution of Inconel Alloy 740 During Solution Treatment, Aging, and Exposure at 760 °C

    SciTech Connect

    Cowen, Christopher J.; Danielson, Paul E.; Jablonski, Paul D.

    2010-08-10

    In this study, the microstructural evolution of Inconel alloy 740 during solution treatment and aging was characterized using optical and scanning electron microscopy. During double solution heat treatment, carbon is liberated from the dissolution of MC carbides during the first solution treatment at 1150 °C, and fine MC carbides are precipitated on gamma grain boundaries during the second solution treatment at 1120 °C. Due to the concurrent decrease in carbon solubility and the increase in the contribution of grain boundary diffusion at lower temperatures, the MC carbides on the gamma grain boundaries provide a localized carbon reservoir that aids in M23C6 carbide precipitation on gamma grain boundaries during exposure at 760 °C. The γ' phase, which is the key strengthening phase in alloy 740, is incorporated into the alloy microstructure during aging at 850 °C. Finally, the main source of microstructural instability observed during exposure at 760 °C was the coarsening of the γ' phase.

  14. Developmental outcomes at preschool age after fetal exposure to valproic acid and lamotrigine: cognitive, motor, sensory and behavioral function.

    PubMed

    Rihtman, Tanya; Parush, Shula; Ornoy, Asher

    2013-11-01

    This prospective, observational study assessed the development of preschool children aged 3-6 years, 11 months (n=124) after in-utero anti-epileptic drug (AED) monotherapy exposure to valproic acid (VPA) (n=30, mean age 52.00[±15.22] months) and lamotrigine (LT) (n=42, mean age 50.12[±12.77] months), compared to non-exposed control children (n=52, mean age 59.96[±14.51] months). As a combined group, AED-exposed children showed reduced non-verbal IQ scores, and lower scores on motor measures, sensory measures, and parent-report executive function, behavioral and attentional measures. When the VPA- and LT-exposed groups were analyzed separately, no cognitive differences were found, but control-VPA and control-LT differences emerged for most motor and sensory measures as well as control-VPA parent-report behavioral and attentional differences. No differences were noted between the VPA and LT groups. These findings suggest that VPA- and LT-exposed children should be monitored on a wider range of developmental measures than currently used, and at differing developmental stages.

  15. Ultraviolet radiation exposure accelerates the accumulation of the aging-dependent T414G mitochondrial DNA mutation in human skin.

    PubMed

    Birket, Matthew J; Birch-Machin, Mark A

    2007-08-01

    The accumulation of mitochondrial DNA (mtDNA) mutations has been proposed as an underlying cause of the aging process. Such mutations are thought to be generated principally through mechanisms involving oxidative stress. Skin is frequently exposed to a potent mutagen in the form of ultraviolet (UV) radiation and mtDNA deletion mutations have previously been shown to accumulate with photoaging. Here we report that the age-related T414G point mutation originally identified in skin fibroblasts from donors over 65 years also accumulates with age in skin tissue. Moreover, there is a significantly greater incidence of this mutation in skin from sun-exposed sites (chi(2)= 6.8, P < 0.01). Identification and quantification of the T414G mutation in dermal skin tissue from 108 donors ranging from 8 to 97 years demonstrated both increased occurrence with photoaging as well as an increase in the proportion of molecules affected. In addition, we have discovered frequent genetic linkage between a common photoaging-associated mtDNA deletion and the T414G mutation. This linkage indicates that mtDNA mutations such as these are unlikely to be distributed equally across the mtDNA population within the skin tissue, increasing their likelihood of exerting focal effects at the cellular level. Taken together, these data significantly contribute to our understanding of the DNA damaging effects of UV exposure and how resultant mutations may ultimately contribute towards premature aging.

  16. Early life exposure to endocrine-disrupting chemicals causes lifelong molecular reprogramming of the hypothalamus and premature reproductive aging.

    PubMed

    Gore, Andrea C; Walker, Deena M; Zama, Aparna M; Armenti, AnnMarie E; Uzumcu, Mehmet

    2011-12-01

    Gestational exposure to the estrogenic endocrine disruptor methoxychlor (MXC) disrupts the female reproductive system at the molecular, physiological, and behavioral levels in adulthood. The current study addressed whether perinatal exposure to endocrine disruptors re-programs expression of a suite of genes expressed in the hypothalamus that control reproductive function and related these molecular changes to premature reproductive aging. Fischer rats were exposed daily for 12 consecutive days to vehicle (dimethylsulfoxide), estradiol benzoate (EB) (1 mg/kg), and MXC (low dose, 20 μg/kg or high dose, 100 mg/kg), beginning on embryonic d 19 through postnatal d 7. The perinatally exposed females were aged to 16-17 months and monitored for reproductive senescence. After euthanasia, hypothalamic regions [preoptic area (POA) and medial basal hypothalamus] were dissected for real-time PCR of gene expression or pyrosequencing to assess DNA methylation of the Esr1 gene. Using a 48-gene PCR platform, two genes (Kiss1 and Esr1) were significantly different in the POA of endocrine-disrupting chemical-exposed rats compared with vehicle-exposed rats after Bonferroni correction. Fifteen POA genes were up-regulated by at least 50% in EB or high-dose MXC compared with vehicle. To understand the epigenetic basis of the increased Esr1 gene expression, we performed bisulfite conversion and pyrosequencing of the Esr1 promoter. EB-treated rats had significantly higher percentage of methylation at three CpG sites in the Esr1 promoter compared with control rats. Together with these molecular effects, perinatal MXC and EB altered estrous cyclicity and advanced reproductive senescence. Thus, early life exposure to endocrine disruptors has lifelong effects on neuroendocrine gene expression and DNA methylation, together with causing the advancement of reproductive senescence.

  17. Landscape development in Southern Peninsular India from 10Be denudation rates in river sands

    NASA Astrophysics Data System (ADS)

    Mandal, Sanjay; Lupker, Maarten; Haghipour, Negar; Burg, Jean-Pierre; Christl, Marcus

    2014-05-01

    The persistence of high elevation and topography observed along many passive margins remains one of the outstanding problems in landscape evolution. In Southern Peninsular India, this question revolves around the understanding of whether the observed high relief and pronounced topography results from equilibrium with contemporaneous external forcing or whether the relief was acquired during the late Cenozoic and conserved over several tens of millions years. Modern denudation rates dictating the current landscape evolution are ruled by the interactions between climate, tectonics and rock strength. We used detrital cosmogenic 10Be from 43 drainage basins ranging in size from 4 to 68768 km2, to infer millennial averaged denudation rates along and across the Western Ghat Mountains in Southern India and to understand if the present landscape is still actively evolving or not. The Western Ghat is characterized by a W-E gradient in relief and rainfall with only minor variations in lithology allowing to isolate the relationship between erosion rates and topographic indices. Cosmogenic-derived erosion rates are spatially variable, ranging from ~8 to 77 mm/ka on the western side and 8 to 51 mm/ka on the eastern side. The rugged topography of Western Ghats and Nilgiri Mountains exhibit pronounced topography in conjunction with low denudation rates. This represents an exception to the often-cited general coupling of topography and denudation rates and suggests that steep slopes and high relief in passive margin settings are not associated to high denudation. Nevertheless, locally the differences in denudation rates along and across the Western Ghats are well correlated with local relief, which suggests that the inherited topography still controls current denudation rates. Even though the catchments in Western Ghats receive a mean annual precipitation ~ 5 m, due to the SW Indian monsoon, precipitation shows only a minor control on denudation rates. This suggests that in the

  18. Cumulative lead exposure is associated with reduced olfactory recognition performance in elderly men: the Normative Aging Study

    PubMed Central

    Grashow, Rachel; Sparrow, David; Hu, Howard; Weisskopf, Marc G.

    2015-01-01

    Introduction Olfactory dysfunction has been identified as an early warning sign for Alzheimer’s disease, Parkinson’s disease, dementia and more. A few occupational and environmental exposures have also been associated with reduced olfactory function, although the effects of long term environmental exposure to lead on olfactory dysfunction have not been explored. Here we performed olfactory recognition testing in elderly men in a community-dwelling cohort and examined the association with cumulative lead exposure, as assessed by lead in tibial and patellar bone. Methods Olfactory recognition was measured in 165 men from the Normative Aging Study (NAS) who had previously taken part in bone lead measurements using K-X-Ray fluorescence (KXRF). Olfactory recognition was measured using the University of Pennsylvania Smell Identification Test (UPSIT). Associations between olfactory recognition, global cognition and cumulative lead exposure were estimated using linear regression, with additional adjustment for age, smoking, and functional polymorphism status for hemochromatosis (HFE), transferrin (TfC2), glutathione-s-transferase Pi1 (GSTP1) and apolipoprotein E (APOE) genotypes. Sensitivity analyses explored olfactory recognition in men with high global cognitive function as measured using the Mini-Mental Status Exam (MMSE). Results The average age of the NAS participants at the time of olfactory recognition testing was 80.3 (standard deviation or SD = 5.7) years. Mean tibia lead was 16.3 (SD = 12.0) μg/g bone, mean patella lead was 22.4 (SD = 14.4) μg/g bone, and mean UPSIT score was 26.9 out of 40 (SD = 7.0). Consistent with previous findings, age at olfaction testing was negatively associated with UPSIT score. Tibia (but not patella) bone lead was negatively associated with olfaction recognition (per 15 μg/g tibia lead: β = −1.57; 95% CI: −2.93, −0.22; p = 0.02) in models adjusted for smoking and age. Additional adjustment for education did not

  19. Exposure to Trihalomethanes through Different Water Uses and Birth Weight, Small for Gestational Age, and Preterm Delivery in Spain

    PubMed Central

    Gracia-Lavedán, Esther; Ibarluzea, Jesús; Santa Marina, Loreto; Ballester, Ferran; Llop, Sabrina; Tardón, Adonina; Fernández, Mariana F.; Freire, Carmen; Goñi, Fernando; Basagaña, Xavier; Kogevinas, Manolis; Grimalt, Joan O.; Sunyer, Jordi

    2011-01-01

    Background: Evidence associating exposure to water disinfection by-products with reduced birth weight and altered duration of gestation remains inconclusive. Objective: We assessed exposure to trihalomethanes (THMs) during pregnancy through different water uses and evaluated the association with birth weight, small for gestational age (SGA), low birth weight (LBW), and preterm delivery. Methods: Mother–child cohorts set up in five Spanish areas during the years 2000–2008 contributed data on water ingestion, showering, bathing, and swimming in pools. We ascertained residential THM levels during pregnancy periods through ad hoc sampling campaigns (828 measurements) and regulatory data (264 measurements), which were modeled and combined with personal water use and uptake factors to estimate personal uptake. We defined outcomes following standard definitions and included 2,158 newborns in the analysis. Results: Median residential THM ranged from 5.9 μg/L (Valencia) to 114.7 μg/L (Sabadell), and speciation differed across areas. We estimated that 89% of residential chloroform and 96% of brominated THM uptakes were from showering/bathing. The estimated change of birth weight for a 10% increase in residential uptake was –0.45 g (95% confidence interval: –1.36, 0.45 g) for chloroform and 0.16 g (–1.38, 1.70 g) for brominated THMs. Overall, THMs were not associated with SGA, LBW, or preterm delivery. Conclusions: Despite the high THM levels in some areas and the extensive exposure assessment, results suggest that residential THM exposure during pregnancy driven by inhalation and dermal contact routes is not associated with birth weight, SGA, LBW, or preterm delivery in Spain. PMID:21810554

  20. SCR and GCR exposure ages of plagioclase grains from lunar soil

    NASA Technical Reports Server (NTRS)

    Etique, P.; Baur, H.; Signer, P.; Wieler, R.

    1986-01-01

    The concentrations of solar wind implanted Ar-36 in mineral grains extracted from lunar soils show that they were exposed to the solar wind on the lunar surface for an integrated time of 10E4 to 10E5 years. From the bulk soil 61501 plagioclase separates of 8 grain size ranges was prepared. The depletion of the implanted gases was achieved by etching aliquot samples of 4 grain sizes to various degrees. The experimental results pertinent to the present discussion are: The spallogenic Ne is, as in most plagioclases from lunar soils, affected by diffusive losses and of no use. The Ar-36 of solar wind origin amounts to (2030 + or - 100) x 10E-8 ccSTP/g in the 150 to 200 mm size fraction and shows that these grains were exposed to the solar wind for at least 10,000 years. The Ne-21/Ne-22 ratio of the spallogenic Ne is 0.75 + or - 0.01 and in very good agreement with the value of this ratio in a plagioclase separate from rock 76535. This rock has had a simple exposure history and its plagioclases have a chemical composition quite similar to those studied. In addition to the noble gases, the heavy particle tracks in an aliquot of the 150 to 200 mm plagioclase separate were investigated and found 92% of the grains to contain more than 10E8 tracks/sq cm. This corresponds to a mean track density of (5 + or - 1) x 10E8 tracks/sq cm. The exploration of the exposure history of the plagioclase separates from the soil 61501 do not contradict the model for the regolith dynamics but also fail to prove it.

  1. Global analysis of the stream power law parameters based on worldwide 10Be denudation rates

    NASA Astrophysics Data System (ADS)

    Harel, M.-A.; Mudd, S. M.; Attal, M.

    2016-09-01

    The stream power law, expressed as E = KAmSn - where E is erosion rate [LT - 1], K is an erodibility coefficient [T - 1L (1 - 2m)], A is drainage area [L 2], S is channel gradient [L/L], and m and n are constants - is the most widely used model for bedrock channel incision. Despite its simplicity and limitations, the model has proved useful for topographic evolution, knickpoint migration, palaeotopography reconstruction, and the determination of rock uplift patterns and rates. However, the unknown parameters K, m, and n are often fixed arbitrarily or are based on assumptions about the physics of the erosion processes that are not always valid, which considerably limits the use and interpretation of the model. In this study, we compile a unique global data set of published basin-averaged erosion rates that use detrital cosmogenic 10Be. These data (N = 1457) enable values for fundamental river properties to be empirically constrained, often for the first time, such as the concavity of the river profile (m/n ratio or concavity index), the link between channel slope and erosion rate (slope exponent n), and substrate erodibility (K). These three parameters are calculated for 59 geographic areas using the integral method of channel profile analysis and allow for a global scale analysis in terms of climatic, tectonic, and environmental settings. In order to compare multiple sites, we also normalize n and K using a reference concavity index m/n = 0.5. A multiple regression analysis demonstrates that intuitive or previously demonstrated local-scale trends, such as the correlation between K and precipitation rates, do not appear at a global scale. Our results suggest that the slope exponent is generally > 1, meaning that the relationship between erosion rate and the channel gradient is nonlinear and thus support the hypothesis that incision is a threshold controlled process. This result questions the validity of many regional interpretations of climate and/or tectonics where

  2. Impact of exposure to community violence, Hurricane Katrina, and Hurricane Gustav on posttraumatic stress and depressive symptoms among school age children.

    PubMed

    Salloum, Alison; Carter, Paulette; Burch, Berre; Garfinkel, Abbe; Overstreet, Stacy

    2011-01-01

    This study examined the relationship between exposure to Hurricane Gustav and distress among 122 children (ages 7-12) to determine whether that relationship was moderated by prior experiences with Hurricane Katrina and exposure to community violence (ECV). Measures of hurricane experiences, ECV, posttraumatic stress (PTS) symptoms, and depression were administered. Assessments occurred after the third anniversary of Katrina, which coincided with the landfall of Gustav. Results indicated that the relation between exposure to Gustav and PTS was moderated by prior experiences. There was a positive association between Gustav exposure and PTS for children who experienced high Katrina exposure and low ECV, with a similar trend for children with high ECV and low Katrina exposure. There was no relationship between Gustav exposure and PTS for children with low Katrina and low ECV or for children with high Katrina and high ECV. The relationship between exposure to Gustav and depression was not moderated by children's prior experience. However, there was a relationship between Katrina exposure and depression for children with high ECV. Results suggest that prior trauma may amplify the relationship between hurricane exposure and distress, but children with high cumulative trauma may remain highly symptomatic regardless of disaster exposure.

  3. Exposure to 56Fe irradiation accelerates normal brain aging and produces deficits in spatial learning and memory

    NASA Astrophysics Data System (ADS)

    Shukitt-Hale, Barbara; Casadesus, Gemma; Carey, Amanda N.; Rabin, Bernard M.; Joseph, James A.

    Previous studies have shown that radiation exposure, particularly to particles of high energy and charge (HZE particles) such as 56Fe, produces deficits in spatial learning and memory. These adverse behavioral effects are similar to those seen in aged animals. It is possible that these shared effects may be produced by the same mechanism. For example, an increased release of reactive oxygen species, and the subsequent oxidative stress and inflammatory damage caused to the central nervous system, is likely responsible for the deficits seen in aging and following irradiation. Therefore, dietary antioxidants, such as those found in fruits and vegetables, could be used as countermeasures to prevent the behavioral changes seen in these conditions. Both aged and irradiated rats display cognitive impairment in tests of spatial learning and memory such as the Morris water maze and the radial arm maze. These rats have decrements in the ability to build spatial representations of the environment, and they utilize non-spatial strategies to solve tasks. Furthermore, they show a lack of spatial preference, due to a decline in the ability to process or retain place (position of a goal with reference to a “map” provided by the configuration of numerous cues in the environment) information. These declines in spatial memory occur in measures dependent on both reference and working memory, and in the flexibility to reset mental images. These results show that irradiation with 56Fe high-energy particles produces age-like decrements in cognitive behavior that may impair the ability of astronauts, particularly middle-aged ones, to perform critical tasks during long-term space travel beyond the magnetosphere.

  4. Influence of age, sex and calendar year on lifetime accumulated red bone marrow dose from diagnostic radiation exposure.

    PubMed

    Hoffmann, Wolfgang; Meiboom, Merle Friederike; Weitmann, Kerstin; Terschüren, Claudia; von Boetticher, Heiner

    2013-01-01

    Our aim is to evaluate the relevance of different factors influencing lifetime accumulated red bone marrow dose, such as calendar year, age and sex. The lifetime dose was estimated for controls interviewed in person (N = 2811, 37.5% women) of the population-based representative Northern Germany Leukemia and Lymphoma Study. Data were assessed in standardized computer-assisted personal interviews. The calculation of doses is based on a comprehensive quantification model including calendar year, sex, kind of examination, and technical development. In multivariate regression models the annual red bone marrow dose was analyzed depending on age, sex and calendar year to consider simultaneously temporal changes in radiologic practice and individual risk factors. While the number of examinations continuously rises over time, the dose shows two peaks around 1950 and after 1980. Men are exposed to higher doses than woman. Until 1970 traditional examinations like conventional and mass screening examinations caused the main dose. They were then replaced by technically advanced examinations mainly computed tomography and cardiac catheter. The distribution of the red bone marrow dose over lifetime depends highly on the technical standards and radiation protection survey. To a lesser extent it is influenced by age and sex of the subjects. Thus epidemiological studies concerning the assessment of radiation exposure should consider the calendar year in which the examination was conducted.

  5. Death anxiety in a national sample of United States funeral directors and its relationship with death exposure, age, and sex.

    PubMed

    Harrawood, Laura K; White, Lyle J; Benshoff, John J

    The purpose of this study is to examine the relationship between the level of death anxiety among a national sample of United States funeral directors with varying levels of death exposure, age, and sex. Utilizing the Multidimensional Fear of Death Scale (MFODS), the results showed a significant, but weak negative relationship between levels of death anxiety and the participants' reported number of funerals attended per year. The correlation between death anxiety scores and the number of reported embalming cases performed yearly was, however, not significant. We found a significant negative correlation between death anxiety and age in both men and women funeral directors. The difference in the death anxiety scores between men (n=166) and women (n=38) funeral directors was not significant. There was a significant negative correlation with age in both men and women in several fears of death including fear of the dying process, fear for significant others, and fear of premature death. The significant negative correlations were stronger for women than men across all three subscales. Results, direction for further research, and implications of the findings for mental health workers are discussed.

  6. [Age, gender and individually-typological characteristics of reaction to acute hypoxic exposure].

    PubMed

    Krivoshchekov, S G; Balioz, N V; Nekipelova, N V; Kapilevich, L V

    2014-01-01

    Individual pequliarities of hypoxic resistance, assessed by the response of cardiorespiratory system to acute normobaric hypoxia (10% O2), were studied in healthy subjects. Age changes in dynamics of blood oxygen saturation after the acute hypoxia are shown at level of separate sites curve SpO2 (phases of a delay, decrease and lifting). It is established, that at children sensitivity to acute hypoxia above, than at teenagers, and at teenagers above, than at adults. Higher lability of mental processes, sympathetic activity, and personal anxiety are associated with choleric temperament. Cholerics are characterized by slower restoration of blood oxygen saturation after the acute hypoxia compared with sanguine persons that we consider an indication of less hypoxic tolerance of the first group. We have developed the complex algorithm, dynamics describing dependence oxygen saturation in various phases of the hypoxic test, which can be used as a universal method of an estimation hypoxic stability at different groups of the population.

  7. A novel facility for ageing materials with narrow-band ultraviolet radiation exposure

    SciTech Connect

    Kaerhae, Petri; Ruokolainen, Kimmo; Heikkilae, Anu

    2011-02-15

    A facility for exploring wavelength dependencies in ultraviolet (UV) radiation induced degradation in materials has been designed and constructed. The device is essentially a spectrograph separating light from a lamp to spectrally resolved UV radiation. It is based on a 1 kW xenon lamp and a flat-field concave holographic grating 10 cm in diameter. Radiation at the wavelength range 250-500 nm is dispersed onto the sample plane of 1.5 cm in height and 21 cm in width. The optical performance of the device has been characterized by radiometric measurements. Using the facility, test samples prepared of regular newspaper have been irradiated from 1 to 8 h. Color changes on the different locations of the aged samples have been quantified by color measurements. Yellowness indices computed from the color measurements demonstrate the capability of the facility in revealing wavelength dependencies of the material property changes in reasonable time frames.

  8. Effects of Age and Exposure on the Health Status of U.S. Navy Divers.

    DTIC Science & Technology

    1984-01-01

    rates for diving-related disorders bI age and esposure level. XI than 17-22 year-olds for diabetes mellitus and no recorded hospital admissions for...11.2 7.0 0 Psychoses 3.1 5.8 0 _b 0 Ulcers 3.4 3.1 8.6 10.4 - Diabetes Mellitus 0.9 1.3 - - 21.3’ Diseases of the Respiratory System 27.8 46.9 30.9 26.1...Neuroses 11.2 3.8" 3.2* Psychoses 5.8 1.5 _b Ulcers 4.5 6.4 3.2 Diabetes Mellitus 1.6 1.9 - Diseases of the Respiratory System 34.8 36.3 31.0 Diseases

  9. Age-dependent effects of in vitro radiofrequency exposure (mobile phone) on CD95+ T helper human lymphocytes.

    PubMed

    Capri, Miriam; Salvioli, Stefano; Altilia, Serena; Sevini, Federica; Remondini, Daniel; Mesirca, Pietro; Bersani, Ferdinando; Monti, Daniela; Franceschi, Claudio

    2006-05-01

    Recent studies on "nonthermal" effects of mobile phone radiofrequency (RF) suggest that RF can interact with cellular functions and molecular pathways. To study the possible RF effects on human lymphocyte activation, we analyzed CD25, CD95, CD28 molecules in unstimulated and stimulated CD4+ e CD8+ T cells in vitro. Peripheral blood mononuclear cells (PBMCs) from young and elderly donors were exposed or sham-exposed to RF (1,800 MHz, Specific Absorption Rate 2 W/kg) with or without mitogenic stimulation. No significant changes in the percentage of these cell subsets were found between exposed and sham-exposed lymphocytes in both young and elderly donors. Nevertheless, after RF exposure we observed a slight, but significant, downregulation of CD95 expression in stimulated CD4+ T lymphocytes from elderly, but not from young donors. This age-related result is noteworthy given the importance of a such molecule in regulation of the immune response.

  10. Damage to the photoreceptor cells of the rabbit retina from 56Fe ions: effect of age at exposure, 1

    NASA Technical Reports Server (NTRS)

    Williams, G. R.; Lett, J. T.; Chatterjee, A. (Principal Investigator)

    1996-01-01

    Optic and proximate tissues of New Zealand white (NZW) rabbits at ages (approximately 3.5 years) near the middle of their median lifespan (5-7 years) were given 0.5-3.5 Gy of 465 MeV u-1 56Fe ions in the Bragg plateau region of energy deposition at a linear energy transfer (LET infinity) of 220 +/- 31 keV micrometer-1. Dose-dependent losses of retinal photoreceptor cells (rods) occurred until 1-2 years after irradiation, the period of this interim report. Similar cumulative losses of photoreceptor cells were seen during the period 1-2 years post-irradiation for rabbits given comparable exposures when young (6-9 weeks old). Since losses of photoreceptor cells at early times had not been determined previously, the current experiment, which was designed to simulate the responses of mature astronauts, redressed that deficiency.

  11. Age of Bilingual Exposure Is Related to the Contribution of Phonological and Semantic Knowledge to Successful Reading Development.

    PubMed

    Jasińska, Kaja K; Petitto, Laura-Ann

    2017-02-07

    Bilingual children's reading as a function of age of first bilingual language exposure (AoE) was examined. Bilingual (varied AoE) and monolingual children (N = 421) were compared in their English language and reading abilities (6-10 years) using phonological awareness, semantic knowledge, and reading tasks. Structural equation modeling was applied to determine how bilingual AoE predicts reading outcomes. Early exposed bilinguals outperformed monolinguals on phonological awareness and word reading. Phonology and semantic (vocabulary) knowledge differentially predicted reading depending on the bilingual experience and AoE. Understanding how bilingual experiences impact phonological awareness and semantic knowledge, and in turn, impact reading outcomes is relevant for our understanding of what language and reading skills are best to focus on, and when, to promote optimal reading success.

  12. Origin, structure and exposure history of a wave-cut platform more than 1 Ma in age at the coast of northern Spain: A multiple cosmogenic nuclide approach

    NASA Astrophysics Data System (ADS)

    Alvarez-Marrón, J.; Hetzel, R.; Niedermann, S.; Menéndez, R.; Marquínez, J.

    2008-01-01

    Along the Asturian coast of northern Spain an uplifted wave-cut platform extends for ˜ 100 km east-west. The steep cliff which bounds the gently seaward-dipping platform to the north increases in height from 30 m in the west to 100 m in the east and reflects the overall eastward increase in platform elevation. The southern edge of the 2-4 km-wide platform runs along the foothills of the Cantabrian Mountains, as constrained by a high-resolution digital elevation model. The marine platform, which was carved into deformed Paleozoic bedrock with abundant quartzite beds, is largely covered by weathered marine and continental sediments. Quartzite samples from flat bedrock outcrops which are currently not covered by sediment or soil yield cosmogenic nuclide concentrations ( 21Ne, 10Be and 26Al) that demonstrate a long and complex exposure history, including periods of burial with partial or complete shielding from cosmic rays. The combination of multiple cosmogenic nuclides yields a minimum age of 1-2 Ma for the platform. Taking into account (i) the horizontal and vertical extent of the platform, (ii) the high resistance to erosion of the quartzitic bedrock, and (iii) published data on the magnitude of past sea level fluctuations, we suggest that the wave-cut platform formed in the Pliocene. Subvertical faults cutting the platform at high angles to the coastline offset the southern edge of the platform by 20 to 40 m and reactivate the pre-existing anisotropy in the Paleozoic bedrock. Uplift and crustal deformation of the coastal region have occurred after platform formation in the Pliocene and may still be active. The slow deformation of the northern edge of the Iberian plate including the Cantabrian Mountains may result from the ongoing slow convergence at an incipient subduction zone extending along the coast of northern Spain.

  13. Prevalence and Associated Factors of Secondhand Smoke Exposure among Internal Chinese Migrant Women of Reproductive Age: Evidence from China’s Labor-Force Dynamic Survey

    PubMed Central

    Gong, Xiao; Luo, Xiaofeng; Ling, Li

    2016-01-01

    Secondhand smoke (SHS) is a major risk factor for poor health outcomes among women in China, where proportionately few women smoke. This is especially the case as it pertains to women’s reproductive health, specifically migrant women who are exposed to SHS more than the population at large. There are several factors which may increase migrant women’s risk of SHS exposure. This paper aims to investigate the prevalence and associated factors of SHS exposure among internal Chinese migrant women of reproductive age. The data used were derived from the 2014 Chinese Labor Dynamic Survey, a national representative panel survey. The age-adjusted rate of SHS exposure of women of reproductive age with migration experience was of 43.46% (95% CI: 40.73%–46.40%), higher than those without migration experience (35.28% (95% CI: 33.66%–36.97%)). Multivariate analysis showed that participants with a marital status of “Widowed” had statistically lower exposure rates, while those with a status of “Cohabitation” had statistically higher exposure. Those with an undergraduate degree or above had statistically lower SHS exposure. Those with increasing levels of social support, and those who currently smoke or drink alcohol, had statistically higher SHS exposure. Participants’ different work-places had an effect on their SHS exposure, with outdoor workers statistically more exposed. Our findings suggest that urgent tobacco control measures should be taken to reduce smoking prevalence and SHS exposure. Specific attention should be paid to protecting migrant women of reproductive age from SHS. PMID:27043604

  14. Association of habitual dietary resveratrol exposure with the development of frailty in older age: the Invecchiare in Chianti study12

    PubMed Central

    Rabassa, Montserrat; Zamora-Ros, Raul; Urpi-Sarda, Mireia; Bandinelli, Stefania; Ferrucci, Luigi; Andres-Lacueva, Cristina; Cherubini, Antonio

    2015-01-01

    Background: Resveratrol may play a protective role against the frailty syndrome (FS) because of its antioxidant and anti-inflammatory properties. Objective: We prospectively evaluated the association between habitual dietary resveratrol exposure and the development of FS after 3-, 6-, and 9-y follow-up periods in a community-dwelling older population. Design: We conducted a longitudinal analysis with the use of data from 769 participants aged ≥65 y from the Invecchiare in Chianti (Aging in Chianti) study. Total dietary resveratrol (TDR) intake was estimated at baseline with the use of a validated food-frequency questionnaire, which was developed to assess participants’ usual food intakes over the previous year, and an ad hoc resveratrol database. Total urinary resveratrol (TUR) was analyzed with the use of liquid chromatography–tandem mass spectrometry with a previous solid-phase extraction at baseline. The combination of both measures [total dietary resveratrol plus total urinary resveratrol (TDR+TUR)] was computed with the use of the Howe’s method. FS was assessed at baseline and at 3-, 6-, and 9-y of follow-up and was defined as the presence of ≥3 of the following 5 criteria: shrinking, exhaustion, sedentariness, slowness, and weakness. Results: TDR+TUR concentrations were inversely associated with FS risk over 3-y of follow-up (OR for comparison of extreme tertiles: 0.11; 95% CI: 0.03, 0.45; P-trend = 0.002) but not after 6- and 9-y of follow-up in multinomial logistic regression models adjusted for baseline frailty status and potential confounders. These results did not differ when analyses were further adjusted for inflammatory markers. Conclusion: Higher habitual dietary resveratrol exposure was associated with lower risk of older community dwellers developing FS during the first 3 y of follow-up but not after longer follow-up periods. PMID:26490492

  15. Correlates of low-level lead exposure in urban children at 2 years of age

    SciTech Connect

    Bellinger, D.; Leviton, A.; Rabinowitz, M.; Needleman, H.; Waternaux, C.

    1986-06-01

    The blood lead levels of a large number of US preschool children approach the value regarded as the upper limit of normal. To reduce the number of children whose levels increase into the range thought to be toxic, the antecedents and correlates of levels in the 0- to 25-micrograms/dL range must be identified. In a large longitudinal study of middle and upper-middle class children living in metropolitan Boston, we evaluated how well five sets of variables predicted children's blood lead levels at 2 years of age: environmental lead sources, mouthing activity, home environment/care giving, prior developmental status, and sociodemographic characteristics. A series of bivariate and multivariate analyses indicated that only environmental lead sources and, to a lesser extent, mouthing activity accounted for significant portions of the variance in blood lead levels. Environmental lead sources were not significantly related to the home environment/care-giving variables or to sociodemographic characteristics. The most promising approach for achieving community-wide reductions in children's blood lead levels is reduction in the amount of lead in the proximate environment.

  16. Extracting tectonic information from cosmogenic exposure ages along bedrock scarps using synthetic and natural data

    NASA Astrophysics Data System (ADS)

    Cowie, Patience; Walker, Matthew; Roberts, Gerald; Phillips, Richard; Dunai, Tibor; Zijerveld, Leo; McCaffrey, Ken

    2010-05-01

    Cosmogenic surface exposure dating is a powerful tool for reconstructing long term slip histories on active faults and extracting earthquake recurrence intervals (e.g. Benedetti et al., GRL, v.29, 2002). Extensional faults are particularly amenable to this type of study because they commonly produce a striated bedrock scarp, exhumed by faulting, that can be directly dated. Bedrock scarps in limestone can be sampled to obtain the concentration of cosmogenic 36Cl, produced primarily through interactions of cosmic ray secondary neutrons and muons with Ca within the scarp limestone. To first order the production rate decreases exponentially with depth beneath the ground surface. Because each normal-faulting earthquake uplifts a new portion of the scarp above the surface, the 36Cl concentration along the scarp is the sum of that 36Cl produced below the surface prior to the earthquake and that accumulated above the surface after the earthquake. For a scarp being seismically exhumed, the characteristic profile is therefore a series of exponentials with discontinuities marking the timing of each earthquake. The number of events, their timing and the magnitude of the associated slip strongly influence the shape of 36Cl profile. Existing methods for extracting paleo-earthquakes from these data are based on a forward modelling approach and have shown that slip events ≥0.5m (≥ Magnitude 6.0) are well resolved by fully sampling the height of the exposed bedrock scarp. A forward model for 36Cl accumulation generates 36Cl concentration versus fault height for different potential fault slip histories, which is then compared with the measured 36Cl concentrations. The best fit scenario(s) are then ranked using the Aikake Information Criterion (AIC), which is sensitive to the goodness of fit as well as the number of parameters included in the model. A key feature of published results using this approach is that slip event