491 research outputs found
Implementation of HERS-ST in Iowa and Development / Refinement of a National Training Program
The Highway Economic Requirements System (HERS) is an economic model that uses highway performance monitoring system (HPMS) data to project future highway conditions and requirements. HERS is a highly complex model that, at the national level, uses samples of the highway network taken from the HPMS data. As a result, at the national level it is only used for aggregate network-level analysis (planning-level analysis). When the Federal Highway Administration’s Office of Asset Management was established in 1999, the office began developing the state version of HERS, or HERS-ST. HERS-ST has since evolved into a model that is specifically crafted for states. A DOS version of HERS-ST was demonstrated at a workshop attended by representatives of several state transportation agencies in 2001. Since then, several improvements have been made to the software, including updates for a Windows environment and the addition of GIS capabilities. The current project will yield a HERS-ST specifically for Iowa, but one that can be used as a model for other states
Estimating behavior in a black box : how coastal oceanographic dynamics influence yearling Chinook salmon marine growth and migration behaviors
Ocean currents or temperature may substantially influence migration behavior in many marine species. However, high-resolution data on animal movement in the marine environment are scarce; therefore, analysts and managers must typically rely on unvalidated assumptions regarding movement, behavior, and habitat use. We used a spatially explicit, individual-based model of early marine migration with two stocks of yearling Chinook salmon to quantify the influence of external forces on estimates of swim speed, consumption, and growth. Model results suggest that salmon behaviorally compensate for changes in the strength and direction of ocean currents. These compensations can result in salmon swimming several times farther than their net movement (straight-line distance) would indicate. However, the magnitude of discrepancy between compensated and straight-line distances varied between oceanographic models. Nevertheless, estimates of relative swim speed among fish groups were less sensitive to the choice of model than estimates of absolute individual swim speed. By comparing groups of fish, this tool can be applied to management questions, such as how experiences and behavior may differ between groups of hatchery fish released early vs. later in the season. By taking into account the experiences and behavior of individual fish, as well as the influence of physical ocean processes, our approach helps illuminate the “black box” of juvenile salmon behavior in the early marine phase of the life cycle
Transforming Growth Factor β Blocks Tec Kinase Phosphorylation, Ca2+ Influx, and NFATc Translocation Causing Inhibition of T Cell Differentiation
Transforming growth factor (TGF)-β inhibits T cell proliferation and differentiation. TGF-β has been shown to inhibit the expression of transcription factors such as GATA-3 and T-bet that play important roles in T cell differentiation. Here we show that TGF-β inhibits T cell differentiation at a more proximal step. An early event during T cell activation is increased intracellular calcium levels. Calcium influx in activated T cells and the subsequent activation of transcription factors such as NFATc, events essential for T cell differentiation, are modulated by the Tec kinases that are downstream of the T cell receptor and CD28. We show that in stimulated CD4+ T cells, TGF-β inhibits phosphorylation and activation of the Tec kinase Itk, increase in intracellular Ca2+ levels, NFATc translocation, and activation of the mitogen-activated protein kinase ERK that together regulate T cell differentiation. Our studies suggest that by inhibiting Itk, and consequently Ca2+ influx, TGF-β limits T cell differentiation along both the Th1 and Th2 lineages
Rethinking Cultural Relations and Exchange in the Critical Zone
Chapter for Managing Culture: Reflecting on Exchange in our Global Times, book edited by Raphaela Henze and Victoria Durrer, to be published by Palgrave: Sociology of the Arts
Multi-Messenger Gravitational Wave Searches with Pulsar Timing Arrays: Application to 3C66B Using the NANOGrav 11-year Data Set
When galaxies merge, the supermassive black holes in their centers may form
binaries and, during the process of merger, emit low-frequency gravitational
radiation in the process. In this paper we consider the galaxy 3C66B, which was
used as the target of the first multi-messenger search for gravitational waves.
Due to the observed periodicities present in the photometric and astrometric
data of the source of the source, it has been theorized to contain a
supermassive black hole binary. Its apparent 1.05-year orbital period would
place the gravitational wave emission directly in the pulsar timing band. Since
the first pulsar timing array study of 3C66B, revised models of the source have
been published, and timing array sensitivities and techniques have improved
dramatically. With these advances, we further constrain the chirp mass of the
potential supermassive black hole binary in 3C66B to less than using data from the NANOGrav 11-year data set. This
upper limit provides a factor of 1.6 improvement over previous limits, and a
factor of 4.3 over the first search done. Nevertheless, the most recent orbital
model for the source is still consistent with our limit from pulsar timing
array data. In addition, we are able to quantify the improvement made by the
inclusion of source properties gleaned from electromagnetic data to `blind'
pulsar timing array searches. With these methods, it is apparent that it is not
necessary to obtain exact a priori knowledge of the period of a binary to gain
meaningful astrophysical inferences.Comment: 14 pages, 6 figures. Accepted by Ap
Explaining Gender-Specific Racial Differences in Obesity Using Biased Self-Reports of Food Intake
Policymakers have an interest in identifying the differences in behavior patterns - namely, habitual caloric intake and physical activity levels - that contribute to demographic variation in body mass index (BMI) and obesity risk. While disparities in mean BMI and obesity rates between whites (non-Hispanic) and African-Americans (non-Hispanic) are well-documented, the behavioral differences that underlie these gaps have not been carefully identified. Moreover, the female-specificity of the black-white obesity gap has received relatively little attention. In the National Health and Nutrition Examination Surveys (NHANES) data, we initially observe a very weak relationship between self-reported measures of caloric intake and physical activity and either BMI or obesity risk, and these behaviors appear to explain only a small fraction of the black-white BMI gap (or obesity gap) among women. These unadjusted estimates echo previous findings from large survey datasets such as the NHANES. Using an innovative method to mitigate the widely recognized problem of measurement error in self-reported behaviors' proxying for measurement errors using the ratio of reported caloric intake to estimated true caloric needs' we obtain much stronger relationships between behaviors and BMI (or obesity risk). Behaviors can in fact account for a significant share of the BMI gap (and the obesity gap) between black women and white women and are consistent with the presence of much smaller gaps between black men and white men. The analysis also shows that the effects smoking has on BMI and obesity risk are small-to-negligible when measurement error is properly controlled
The NANOGrav 11-year Data Set: High-precision Timing of 45 Millisecond Pulsars
We present high-precision timing data over time spans of up to 11 years for 45 millisecond pulsars observed as part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project, aimed at detecting and characterizing low-frequency gravitational waves. The pulsars were observed with the Arecibo Observatory and/or the Green Bank Telescope at frequencies ranging from 327 MHz to 2.3 GHz. Most pulsars were observed with approximately monthly cadence, and six high-timing-precision pulsars were observed weekly. All were observed at widely separated frequencies at each observing epoch in order to fit for time-variable dispersion delays. We describe our methods for data processing, time-of-arrival (TOA) calculation, and the implementation of a new, automated method for removing outlier TOAs. We fit a timing model for each pulsar that includes spin, astrometric, and (for binary pulsars) orbital parameters; time-variable dispersion delays; and parameters that quantify pulse-profile evolution with frequency. The timing solutions provide three new parallax measurements, two new Shapiro delay measurements, and two new measurements of significant orbital-period variations. We fit models that characterize sources of noise for each pulsar. We find that 11 pulsars show significant red noise, with generally smaller spectral indices than typically measured for non-recycled pulsars, possibly suggesting a different origin. A companion paper uses these data to constrain the strength of the gravitational-wave background
Bimolecular porous supramolecular networks deposited from solution on layered materials: graphite, boron nitride and molybdenum disulphide
A two-dimensional porous network formed from perylene tetracarboxylic diimide (PTCDI) and melamine may be deposited from
solution on the surfaces of highly oriented pyrolytic graphite (HOPG), hexagonal boron nitride (hBN) and molybdenum disulphide (MoS2). Images acquired using high resolution atomic force microscopy (AFM) operating under ambient conditions have revealed that the network forms extended orderedmonolayers (41 lm2) on HOPG and hBN whereas on MoS2 much smaller islands are observed
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