95 research outputs found
Legacy and Novel Per- and Polyfluoroalkyl Substances in Juvenile Seabirds from the U.S. Atlantic Coast
Per- and polyfluoroalkyl substances (PFAS) are anthropogenic, globally distributed chemicals. Legacy PFAS, including perfluorooctane sulfonate (PFOS), have been regularly detected in marine fauna but little is known about their current levels or the presence of novel PFAS in seabirds. We measured 36 emerging and legacy PFAS in livers from 31 juvenile seabirds from Massachusetts Bay, Narragansett Bay, and the Cape Fear River Estuary (CFRE), United States. PFOS was the major legacy perfluoroalkyl acid present, making up 58% of concentrations observed across all habitats (range: 11â280 ng/g). Novel PFAS were confirmed in chicks hatched downstream of a fluoropolymer production site in the CFRE: a perfluorinated ether sulfonic acid (Nafion byproduct 2; range: 1â110 ng/g) and two perfluorinated ether carboxylic acids (PFO4DA and PFO5DoDA; PFO5DoDA range: 5â30 ng/g). PFOS was inversely associated with phospholipid content in livers from CFRE and Massachusetts Bay individuals, while ÎŽ 13C, an indicator of marine versus terrestrial foraging, was positively correlated with some long-chain PFAS in CFRE chick livers. There is also an indication that seabird phospholipid dynamics are negatively impacted by PFAS, which should be further explored given the importance of lipids for seabirds
100 kV Schottky electron gun
We present a comparison between experimental results and computer calculations on a high current, high resolution single lens electrostatic 100 kV Schottky electron gun. One promising application for such an electron gun is for direct electronâbeam patterning of xâray masks. The high energy helps provide precise patterning of the thick resist, maintains vertical resist profiles, and minimizes the proximity effect. The gun was designed to operate from 25 to 100 kV, capable of focus at a distance of 145â245 mm with a magnification of 1.15. The emitter, of apex radius âŒ0.6 ÎŒm operated at 1800 K in the extended Schottky regime, provides an angular intensity of 0.5 mA/sr for an extraction voltage of 5000 V and with a beam limiting aperture of 2.2 mrad, the gun delivers 7 nA of probe current. The gun consists of a replaceable high voltage optic module mounted on a precision insulator with the main acceleration occurring between the exit of the optic module and the grounded anode. A provision is made for alignment of the emitter with respect to the central optical axis of the optic module in a special alignment chamber eliminating the need for high voltage emitter alignment. Final gun alignment is achieved by XâY motion of the grounded anodeaperture. The gun is constructed to allow ease of replacement of the emitter, the beam defining aperture, and the differential pumping aperture. The beam supply has 10 ppm of ripple while lens supplies have supply, cabling, connectors,insulator, and optic module draw 1 ÎŒA of ground leakage current. Pressured SF6 chambers are used for high voltage connector interfaces within the power supply and on the gun
AVAST Survey 0.4-1.0 {\mu}m Spectroscopy of Igneous Asteroids in the Inner and Middle Main Belt
We present the spectra of 60 asteroids, including 47 V-types observed during
the first phase of the Adler V-Type Asteroid (AVAST) Survey. SDSS photometry
was used to select candidate V-type asteroids for follow up by nature of their
very blue color. 47 of the 61 observed candidates were positively
classified as V-type asteroids, while an additional six show indications of a
0.9 m feature consistent with V-type spectra, but not sufficient for
formal classification. Four asteroids were found to be S-type, all of which had
values very near the adopted AVAST selection criteria of ,
including one candidate observed well outside the cut (at a mean of
-0.11). Three A-type asteroids were also identified. Six V-type asteroids were
observed beyond the 3:1 mean motion resonance with Jupiter, including the
identification of two new V-type asteroids (63085 and 105041) at this distance.
Six V-type asteroids were observed with low () orbital inclination,
outside of the normal dynamical range of classic Vestoids, and are suggestive
of a non-Vesta origin for at least some of the population.Comment: 1 table, 3 figures, To appear to Icaru
Determining Segment and Network Traffic Volumes from Video Imagery Obtained from Transit Buses in Regular Service: Developments and Evaluation of Approaches for Ongoing Use across Urban Networks
69A3551747111Transit agencies around the world are increasingly mounting video cameras inside and outside their buses for liability, safety, and security reasons. Some of the cameras provide fields of view that allow observation of vehicles traveling on the surrounding roadways. Such video imagery could conceivably be used to estimate traffic volumes on roadway segments traversed by the transit buses. Transit buses are attractive platforms for acquiring the information that leads to traffic volume estimates, since a fleet of transit buses collectively covers most major surface streets in an urban area and the buses regularly and repeatedly cover the same roadway segments, which would allow for multiple, independent estimates of roadway segment flows across days and by time of day. Since the video cameras are already installed for other purposes, the costs of estimating traffic flows from video obtained from transit buses in regular service would be minimal. Therefore, traffic flows could be estimated with much greater geographic coverage, with much greater frequency, and with much lower cost than is presently available from existing traffic volume observation methods
Microbiota alter metabolism and mediate neurodevelopmental toxicity of 17ÎČ-estradiol
Estrogenic chemicals are widespread environmental contaminants associated with diverse health and ecological effects. During early vertebrate development, estrogen receptor signaling is critical for many different physiologic responses, including nervous system function. Recently, host-associated microbiota have been shown to influence neurodevelopment. Here, we hypothesized that microbiota may biotransform exogenous 17-ÎČestradiol (E2) and modify E2 effects on swimming behavior. Colonized zebrafish were continuously exposed to non-teratogenic E2 concentrations from 1 to 10 days post-fertilization (dpf). Changes in microbial composition and predicted metagenomic function were evaluated. Locomotor activity was assessed in colonized and axenic (microbe-free) zebrafish exposed to E2 using a standard light/dark behavioral assay. Zebrafish tissue was collected for chemistry analyses. While E2 exposure did not alter microbial composition or putative function, colonized E2-exposed larvae showed reduced locomotor activity in the light, in contrast to axenic E2-exposed larvae, which exhibited normal behavior. Measured E2 concentrations were significantly higher in axenic relative to colonized zebrafish. Integrated peak area for putative sulfonated and glucuronidated E2 metabolites showed a similar trend. These data demonstrate that E2 locomotor effects in the light phase are dependent on the presence of microbiota and suggest that microbiota influence chemical E2 toxicokinetics. More broadly, this work supports the concept that microbial colonization status may influence chemical toxicity
Number of years of participation in some, but not all, types of physical activity during adolescence predicts level of physical activity in adulthood: Results from a 13-year study
Abstract: Background: Adolescent physical activity (PA) levels track into adulthood. However it is not known if type of PA participated in during adolescence is associated with PA levels later in life. We aimed to identify natural groupings of types of PA and to assess whether number of years participating in these different groupings during adolescence is related to PA level in early adulthood. Methods: 673 adolescents in Montreal, Canada, age 12â13 years at baseline (54 % female), reported participation in 29 physical activities every 3 months over 5 years (1999â2005). They also reported their PA level at age 24 years (2011â12). PA groupings among the 29 physical activities were identified using factor analysis. The association between number of years participating in each grouping during adolescence and PA level at age 24 was estimated using linear regression within a general estimating equation framework. Results: Three PA groupings were identified: âsportsâ, âfitness and danceâ, and ârunningâ. There was a positive linear relationship between number of years participating in sports and running in adolescence and PA level at age 24 years (ÎČ (95 % confidence interval) = 0.09 (0.04-0.15); 0.08 (0.01-0.15), respectively). There was no relationship between fitness and dance in adolescence and PA level at age 24. Conclusions: The association between PA participation in adolescence and PA levels in young adulthood may be specific to certain PA types and to consistency of participation during adolescence. Results suggest that efforts to establish the habit of participation in sports and running in adolescence may promote higher PA levels in adulthood
TDP-43 Identified from a Genome Wide RNAi Screen for SOD1 Regulators
Amyotrophic Lateral Sclerosis (ALS) is a late-onset, progressive neurodegenerative disease affecting motor neurons in the brain stem and spinal cord leading to loss of voluntary muscular function and ultimately, death due to respiratory failure. A subset of ALS cases are familial and associated with mutations in superoxide dismutase 1 (SOD1) that destabilize the protein and predispose it to aggregation. In spite of the fact that sporadic and familial forms of ALS share many common patho-physiological features, the mechanistic relationship between SOD1-associated and sporadic forms of the disease if any, is not well understood. To better understand any molecular connections, a cell-based protein folding assay was employed to screen a whole genome RNAi library for genes that regulate levels of soluble SOD1. Statistically significant hits that modulate SOD1 levels, when analyzed by pathway analysis revealed a highly ranked network containing TAR DNA binging protein (TDP-43), a major component of aggregates characteristic of sporadic ALS. Biochemical experiments confirmed the action of TDP-43 on SOD1. These results highlight an unexpected relationship between TDP-43 and SOD1 which may have implications in disease pathogenesis
Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases
The production of peroxide and superoxide is an inevitable consequence of
aerobic metabolism, and while these particular "reactive oxygen species" (ROSs)
can exhibit a number of biological effects, they are not of themselves
excessively reactive and thus they are not especially damaging at physiological
concentrations. However, their reactions with poorly liganded iron species can
lead to the catalytic production of the very reactive and dangerous hydroxyl
radical, which is exceptionally damaging, and a major cause of chronic
inflammation. We review the considerable and wide-ranging evidence for the
involvement of this combination of (su)peroxide and poorly liganded iron in a
large number of physiological and indeed pathological processes and
inflammatory disorders, especially those involving the progressive degradation
of cellular and organismal performance. These diseases share a great many
similarities and thus might be considered to have a common cause (i.e.
iron-catalysed free radical and especially hydroxyl radical generation). The
studies reviewed include those focused on a series of cardiovascular, metabolic
and neurological diseases, where iron can be found at the sites of plaques and
lesions, as well as studies showing the significance of iron to aging and
longevity. The effective chelation of iron by natural or synthetic ligands is
thus of major physiological (and potentially therapeutic) importance. As
systems properties, we need to recognise that physiological observables have
multiple molecular causes, and studying them in isolation leads to inconsistent
patterns of apparent causality when it is the simultaneous combination of
multiple factors that is responsible. This explains, for instance, the
decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference
Influence of population and exercise protocol characteristics on hemodynamic determinants of post-aerobic exercise hypotension
2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS guideline for the diagnosis and management of patients with stable ischemic heart disease
The recommendations listed in this document are, whenever possible, evidence based. An extensive evidence review was conducted as the document was compiled through December 2008. Repeated literature searches were performed by the guideline development staff and writing committee members as new issues were considered. New clinical trials published in peer-reviewed journals and articles through December 2011 were also reviewed and incorporated when relevant. Furthermore, because of the extended development time period for this guideline, peer review comments indicated that the sections focused on imaging technologies required additional updating, which occurred during 2011. Therefore, the evidence review for the imaging sections includes published literature through December 2011
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