2,842 research outputs found
A Meta-Analysis of Driving Performance and Crash Risk Associated with the Use of Cellular Telephones While Driving
This paper addresses the effects of cell phones on driving by means of a review of the literature and an analysis of scientifically credible epidemiological and driver performance studies. A total of 84 articles were obtained covering the period from 1969 to 2004. Sixty-eight articles were research papers measuring driving performance while using a cell phone and 16 articles were epidemiological studies that examined cell phone usage and their relationship to vehicular crashes. Epidemiological findings consistently showed an increase in crashes associated with use of cell phones. However, these studies did not control for exposure to cell phone use or to driving. The negative impact of cell phone usage is larger for responses to critical events than for vehicular control. Drivers responded about a quarter of a second later to stimuli in the presence of a cell phone distractor for all studies that were analyzed. Hands-free cell phones produced similar performance decrements to hand-held phones
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Characterization of designed, synthetically accessible bryostatin analog HIV latency reversing agents.
HIV latency in resting CD4+ T cell represents a key barrier preventing cure of the infection with antiretroviral drugs alone. Latency reversing agents (LRAs) can activate HIV expression in latently infected cells, potentially leading to their elimination through virus-mediated cytopathic effects, host immune responses, and/or therapeutic strategies targeting cells actively expressing virus. We have recently described several structurally simplified analogs of the PKC modulator LRA bryostatin (termed bryologs) designed to improve synthetic accessibility, tolerability in vivo, and efficacy in inducing HIV latency reversal. Here we report the comparative performance of lead bryologs, including their effects in reducing cell surface expression of HIV entry receptors, inducing proinflammatory cytokines, inhibiting short-term HIV replication, and synergizing with histone deacetylase inhibitors to reverse HIV latency. These data provide unique insights into structure-function relationships between A- and B-ring bryolog modifications and activities in primary cells, and suggest that bryologs represent promising leads for preclinical advancement
High Spatial and Temporal Resolution Census Data Reveals Communities at Risk Along the Wildland-Urban Interface (WUI) in California, USA
We tracked census tract level population change along California\u27s wild land-urban interface (WUI) during the past decade (2010-2019), an ecological sensitive region transitioning from developed land to wilderness. Our results from Mann-Kendall analysis, a method employed for monotonic trend detection showed that about one-third (29.1%) of census tracts in California’s WUI have seen a significant population increase from 2010 to 2019, affecting 12.7% population in California.
The population increase along WUI is largely driven by the sixteen counties in the San Francisco Bay Area (10) and Southern California (6). We also found that higher proportion of WUI residents in Bay Area and larger number of WUI residents in Southern California. Bay Area counties in general have a higher proportion of population living in WUI tracts with significant population increase than Southern California counties. However, the lower proportion of residents living in WUI in Southern California counties account for a much larger population. Riverside is the county with the highest number of residents living in WUI tracts that have experienced significant population increase during the past decade. These residents also account for a high proportion (29.2%) of total population in Riverside. Preliminary results showed that the increase of population along WUI is driven by the house affordability and house ownership in 16 counties of Bay Area and Southern California. These factors can still explain a significant amount of the spatial pattern if extended to all counties in California
Thermal and magnetic properties of a low-temperature antiferromagnet CePtSn
We report specific heat () and magnetization () of single crystalline
CePtSn at temperature down to 50mK and in fields up to
3T. exhibits a sharp anomaly at 180mK, with a large 30J/molK-Ce, which, together with the corresponding cusp-like
magnetization anomaly, indicates an antiferromagnetic (AFM) ground state with a
N\'eel temperature =180mK. Numerical calculations based on a Heisenberg
model reproduce both zero-field and data, thus placing
CePtSn in the weak exchange coupling limit of the
Doniach diagram, with a very small Kondo scale . Magnetic field
suppresses the AFM state at 0.7T, much more effectively than
expected from the Heisenberg model, indicating additional effects possibly due
to frustration or residual Kondo screening.Comment: 8 pages, 7 figures, accepted for publication in Phys. Rev.
Influence of rain on air-sea gas exchange : lessons from a model ocean
Author Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 109 (2004): C08S18, doi:10.1029/2003JC001806.Rain has been shown to significantly enhance the rate of air-water gas exchange in fresh water environments, and the mechanism behind this enhancement has been studied in laboratory experiments. In the ocean, the effects of rain are complicated by the potential influence of density stratification at the water surface. Since it is difficult to perform controlled rain-induced gas exchange experiments in the open ocean, an SF6 evasion experiment was conducted in the artificial ocean at Biosphere 2. The measurements show a rapid depletion of SF6 in the surface layer due to rain enhancement of air-sea gas exchange, and the gas transfer velocity was similar to that predicted from the relationship established from freshwater laboratory experiments. However, because vertical mixing is reduced by stratification, the overall gas flux is lower than that found during freshwater experiments. Physical measurements of various properties of the ocean during the rain events further elucidate the mechanisms behind the observed response. The findings suggest that short, intense rain events accelerate gas exchange in oceanic environments.Funding was provided by a generous grant from
the David and Lucile Packard Foundation
Fermi-surface topologies and low-temperature phases of the filled skutterudite compounds CeOs4Sb12 and NdOs4Sb12
MHz conductivity, torque magnetometer and magnetization measurements are reported on single crystals of CeOs4Sb12 and NdOs4Sb12 using temperatures down to 0.5 K and magnetic fields of up to 60 tesla. The field-orientation dependence of the de Haas-van Alphen and Shubnikov-de Haas oscillations is deduced by rotating the samples about the [010] and [0¯11] directions. The results indicate that NdOs4Sb12 has a similar Fermi surface topology to that of the unusual superconductor PrOs4Sb12, but with significantly smaller effective masses, supporting the importance of local phonon modes in contributing to the low-temperature heat capacity of NdOs4Sb12. By contrast, CeOs4Sb12 undergoes a field-induced transition from an unusual semimetal into a high-field, hightemperature state characterized by a single, almost spherical Fermi-surface section. The behavior of the phase boundary and comparisons with models of the bandstructure lead us to propose that the field-induced phase transition in CeOs4Sb12 is similar in origin to the well-known α − γ transition in Ce and its alloys
The Type Ic Supernova 1994I in M51: Detection of Helium and Spectral Evolution
We present a series of spectra of SN 1994I in M51, starting 1 week prior to maximum brightness. The nebular phase began about 2 months after the explosion; together with the rapid decline of the optical light, this suggests that the ejected mass was small. Although lines of He I in the optical region are weak or absent, consistent with the Type Ic classification, we detect strong He I λ10830 absorption during the first month past maximum. Thus, if SN 1994I is a typical Type Ic supernova, the atmospheres of these objects cannot be completely devoid of helium. The emission-line widths are smaller than predicted by the model of Nomoto and coworkers, in which the iron core of a low-mass carbon-oxygen star collapses. They are, however, larger than in Type Ib supernovae
Mechanical design and development of TES bolometer detector arrays for the Advanced ACTPol experiment
The next generation Advanced ACTPol (AdvACT) experiment is currently underway
and will consist of four Transition Edge Sensor (TES) bolometer arrays, with
three operating together, totaling ~5800 detectors on the sky. Building on
experience gained with the ACTPol detector arrays, AdvACT will utilize various
new technologies, including 150mm detector wafers equipped with multichroic
pixels, allowing for a more densely packed focal plane. Each set of detectors
includes a feedhorn array of stacked silicon wafers which form a spline profile
leading to each pixel. This is then followed by a waveguide interface plate,
detector wafer, back short cavity plate, and backshort cap. Each array is
housed in a custom designed structure manufactured from high purity copper and
then gold plated. In addition to the detector array assembly, the array package
also encloses cryogenic readout electronics. We present the full mechanical
design of the AdvACT high frequency (HF) detector array package along with a
detailed look at the detector array stack assemblies. This experiment will also
make use of extensive hardware and software previously developed for ACT, which
will be modified to incorporate the new AdvACT instruments. Therefore, we
discuss the integration of all AdvACT arrays with pre-existing ACTPol
infrastructure.Comment: 9 pages, 5 figures, SPIE Astronomical Telescopes and Instrumentation
conference proceeding
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