66 research outputs found
Polycyclic Aromatic Hydrocarbon Accumulation in Soil Receiving Rooftop Runoff
Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants that are ubiquitous in the environment and can potentially impact human health. The main objective of this study was to qualify and quantify PAH accumulation (especially the seven potentially carcinogenic PAHs (cPAHs)) throughout the Oklahoma City Metro Area and to investigate factors that could be related to higher accumulation. Factors included building use (residential, commercial, and school) and roofing type (asphalt, metal, and tar). To determine if cPAH concentrations were higher in soil receiving direct rooftop runoff, paired runoff receiving contact samples and reference samples (not receiving rooftop runoff) were evaluated from each site. In addition to determining the presence of certain PAHs, a digestive model was applied to give an indication as to what percent of the overall PAHs become bioavailable if contaminated soil is ingested. Overall 77% of the locations analyzed had levels of cPAHs above the USEPAâs soil screening level (SSL). Benzo[a]pyrene (BaP), a known carcinogenic PAH, appeared above SSL in 74% of the samples, with the 95th percentile of runoff contact samples at 880 ppb. Contact soil samples surrounding schools had the highest significant values of cPAHs contamination within building usage, with 95th percentile concentrations of cPAH for soil receiving rooftop runoff at 140,000 ppb. Schools and commercial contact soils had significantly elevated levels of cPAHs and BaP as compared to residential contact soils. Roof type did not vary in contributing to cPAH or BaP levels in contact samples. cPAHs and BaP concentrations in contact soils were significantly greater within each sampling subset compared to the paired reference sample. The digestive model indicated that some of the soils with the highest concentrations of cPAHs and BaP had less than 3% bioavailability. Values of some samples were still more than 100 ppb bioavailable, but there was a great decrease in concentration of cPAHs within the bioavailable fraction. Because many high concentrated cPAH soils were found in school areas, school sites should be further investigated for contamination. While these sites may not show high potentials for bioavailability, the magnitude of cPAH concentrations in soil is still a cause for concern.Zoolog
Estimating Sizes of Key Populations at the National Level: Considerations for Study Design and Analysis.
BACKGROUND: National estimates of the sizes of key populations, including female sex workers, men who have sex with men, and transgender women are critical to inform national and international responses to the HIV pandemic. However, epidemiologic studies typically provide size estimates for only limited high priority geographic areas. This article illustrates a two-stage approach to obtain a national key population size estimate in the Dominican Republic using available estimates and publicly available contextual information. METHODS: Available estimates of key population size in priority areas were augmented with targeted additional data collection in other areas. To combine information from data collected at each stage, we used statistical methods for handling missing data, including inverse probability weights, multiple imputation, and augmented inverse probability weights. RESULTS: Using the augmented inverse probability weighting approach, which provides some protection against parametric model misspecification, we estimated that 3.7% (95% CI = 2.9, 4.7) of the total population of women in the Dominican Republic between the ages of 15 and 49 years were engaged in sex work, 1.2% (95% CI = 1.1, 1.3) of men aged 15-49 had sex with other men, and 0.19% (95% CI = 0.17, 0.21) of people assigned the male sex at birth were transgender. CONCLUSIONS: Viewing the size estimation of key populations as a missing data problem provides a framework for articulating and evaluating the assumptions necessary to obtain a national size estimate. In addition, this paradigm allows use of methods for missing data familiar to epidemiologists
On-sky performance of new 90 GHz detectors for the Cosmology Large Angular Scale Surveyor (CLASS)
The Cosmology Large Angular Scale Surveyor (CLASS) is a
polarization-sensitive telescope array located at an altitude of 5,200 m in the
Chilean Atacama Desert and designed to measure the polarized Cosmic Microwave
Background (CMB) over large angular scales. The CLASS array is currently
observing with three telescopes covering four frequency bands: one at 40 GHz
(Q); one at 90 GHz (W1); and one dichroic system at 150/220 GHz (HF). During
the austral winter of 2022, we upgraded the first 90 GHz telescope (W1) by
replacing four of the seven focal plane modules. These new modules contain
detector wafers with an updated design, aimed at improving the optical
efficiency and detector stability. We present a description of the design
changes and measurements of on-sky optical efficiencies derived from
observations of Jupiter.Comment: 5 pages, 3 figures, to appear in the IEEE Transactions on Applied
Superconductivity. arXiv admin note: text overlap with arXiv:2208.0500
LSST Science Book, Version 2.0
A survey that can cover the sky in optical bands over wide fields to faint
magnitudes with a fast cadence will enable many of the exciting science
opportunities of the next decade. The Large Synoptic Survey Telescope (LSST)
will have an effective aperture of 6.7 meters and an imaging camera with field
of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over
20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with
fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a
total point-source depth of r~27.5. The LSST Science Book describes the basic
parameters of the LSST hardware, software, and observing plans. The book
discusses educational and outreach opportunities, then goes on to describe a
broad range of science that LSST will revolutionize: mapping the inner and
outer Solar System, stellar populations in the Milky Way and nearby galaxies,
the structure of the Milky Way disk and halo and other objects in the Local
Volume, transient and variable objects both at low and high redshift, and the
properties of normal and active galaxies at low and high redshift. It then
turns to far-field cosmological topics, exploring properties of supernovae to
z~1, strong and weak lensing, the large-scale distribution of galaxies and
baryon oscillations, and how these different probes may be combined to
constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at
http://www.lsst.org/lsst/sciboo
Climatic and geographic predictors of life history variation in Eastern Massasauga (Sistrurus catenatus): A range-wide synthesis
Elucidating how life history traits vary geographically is important to understanding variation in population dynamics. Because many aspects of ectotherm life history are climate-dependent, geographic variation in climate is expected to have a large impact on population dynamics through effects on annual survival, body size, growth rate, age at first reproduction, size-fecundity relationship, and reproductive frequency. The Eastern Massasauga (Sistrurus catenatus) is a small, imperiled North American rattlesnake with a distribution centered on the Great Lakes region, where lake effects strongly influence local conditions. To address Eastern Massasauga life history data gaps, we compiled data from 47 study sites representing 38 counties across the range. We used multimodel inference and general linear models with geographic coordinates and annual climate normals as explanatory variables to clarify patterns of variation in life history traits. We found strong evidence for geographic variation in six of nine life history variables. Adult female snout-vent length and neonate mass increased with increasing mean annual precipitation. Litter size decreased with increasing mean temperature, and the size-fecundity relationship and growth prior to first hibernation both increased with increasing latitude. The proportion of gravid females also increased with increasing latitude, but this relationship may be the result of geographically varying detection bias. Our results provide insights into ectotherm life history variation and fill critical data gaps, which will inform Eastern Massasauga conservation efforts by improving biological realism for models of population viability and climate change
Overgrowth of rhodium on gold nanorods
[Image: see text] This study focuses on the deposition and growth mode of rhodium (Rh) on gold (Au) seed nanorods (NRs). Using a combination of scanning transmission electron microscopy imaging, energy-dispersive X-ray spectroscopy, and UVâvisible absorption spectroscopy, we show that Rh deposition results in an uneven overlayer morphology on the Au NR seeds, with a tendency for Rh deposition to occur preferentially on the Au NR ends. The results suggest that complex and kinetically driven metalâmetal interactions take place in this system
CMB-S4: Forecasting Constraints on Primordial Gravitational Waves
CMB-S4---the next-generation ground-based cosmic microwave background (CMB)
experiment---is set to significantly advance the sensitivity of CMB
measurements and enhance our understanding of the origin and evolution of the
Universe, from the highest energies at the dawn of time through the growth of
structure to the present day. Among the science cases pursued with CMB-S4, the
quest for detecting primordial gravitational waves is a central driver of the
experimental design. This work details the development of a forecasting
framework that includes a power-spectrum-based semi-analytic projection tool,
targeted explicitly towards optimizing constraints on the tensor-to-scalar
ratio, , in the presence of Galactic foregrounds and gravitational lensing
of the CMB. This framework is unique in its direct use of information from the
achieved performance of current Stage 2--3 CMB experiments to robustly forecast
the science reach of upcoming CMB-polarization endeavors. The methodology
allows for rapid iteration over experimental configurations and offers a
flexible way to optimize the design of future experiments given a desired
scientific goal. To form a closed-loop process, we couple this semi-analytic
tool with map-based validation studies, which allow for the injection of
additional complexity and verification of our forecasts with several
independent analysis methods. We document multiple rounds of forecasts for
CMB-S4 using this process and the resulting establishment of the current
reference design of the primordial gravitational-wave component of the Stage-4
experiment, optimized to achieve our science goals of detecting primordial
gravitational waves for at greater than , or, in the
absence of a detection, of reaching an upper limit of at CL.Comment: 24 pages, 8 figures, 9 tables, submitted to ApJ. arXiv admin note:
text overlap with arXiv:1907.0447
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