2,682 research outputs found
Data From: Active Transportation Counts from Existing On-Street Signal and Detection Infrastructure
This study’s objective was to use data from existing traffic signal infrastructure to estimate pedestrian volumes. Pedestrian push-button actuations were collected from signal controller logs at 49 intersections in western Oregon and an additional 16 intersections in eastern Oregon. These actuations were then compared to observed pedestrian counts, totaling over 34,000 people, obtained from video recordings. After exploring various options, a simple quadratic relationship was modeled using a single measure of pedestrian signal activity: the number of push-button presses (filtered to remove multiple presses within 15 seconds). The model’s predictions showed a correlation of 0.86 with observed pedestrian volumes and had an average error of ±2.4 pedestrians per hour. These results suggest that existing traffic signal infrastructure data can be used to estimate pedestrian volumes in Oregon with reasonable accuracy. Using such pedestrian volume estimates can lead to improvements in pedestrian traffic monitoring, safety assessments of exposure, and equity and health analyses
Biomarkers of oxidant stress, insulin sensitivity and endothelial activation in rheumatoid arthritis: a cross-sectional study of their association with accelerated atherosclerosis
<p>Abstract</p> <p>Background</p> <p>Women with rheumatoid arthritis (RA) have increased morbidity and mortality due to coronary heart disease. Chronic systemic inflammation is known to accelerate atherosclerosis and increase arterial stiffness in patients, but other mechanisms may also be involved. Biomarkers of oxidant stress, inflammation, insulinaemia and endothelial dysfunction were measured in blood and urine from 46 RA patients and 48 age-matched controls. Plaque formation and intima-medial thickness (IMT) were measured using B-mode carotid Doppler scan.</p> <p>Findings</p> <p>The prevalence of plaque was increased (p = 0.042) in RA patients between 50–59 years old compared to the same age group in controls. 8-isoprostane (p = 0.004), C-reactive protein (p < 0.001), interleukin-6 (p < 0.001), insulin (p = 0.035), adiponectin (p = 0.012), vascular cell adhesion molecule (VCAM) (p = 0.029) and E-selectin (p < 0.001) were all increased while selenium (p = 0.003) and LDL-cholesterol (p = 0.025) were both decreased in all RA patients. 8-isoprostane correlated with 10 year cardiac risk (r = 0.55, p < 0.001), VCAM with IMT (r = 0.37, p = 0.012) and E-selectin with rheumatoid factor titre (r = 0.43, p = 0.003) in RA patients. In the control group, age, carotid IMT, VCAM, systolic blood pressure and smoking status were all associated with plaque development whereas in RA patients only age was associated with plaque.</p> <p>Conclusion</p> <p>The burden of atherosclerosis is particularly increased in middle-aged women with RA. Patients with RA have increased levels of oxidant stress, inflammation, insulin and soluble adhesion molecules. As the association between classical risk factors was much weaker in RA patients compared to controls, these additional factors may be more important in the accelerated development of atheroma in RA.</p
Representing environmental harm and resistance on Twitter: The case of the TAP pipeline
This research explores a new methodological path for doing green cultural criminological research via social media. It provides original case-study data and aims to stimulate further empirical and theoretical debate. In particular, the study explores how Twitter users have represented the harms related to an ongoing pipeline project in Italy (referred to as TAP), and the resistance to those harms. To these ends, it offers a virtual and visual ethnography of Twitter posts and posted images
The evolution of a network of cosmic string loops
We set up and analyse a model for the non-equilibrium evolution of a network
of cosmic strings initially containing only loops and no infinite strings. Due
to this particular initial condition, our analytical approach differs
significantly from existing ones. We describe the average properties of the
network in terms of the distribution function n(l,t) dl, the average number of
loops per unit volume with physical length between l and l + dl at time t. The
dynamical processes which change the length of loops are then estimated and an
equation, which we call the `rate equation', is derived for (dn/dt). In a
non-expanding universe, the loops should reach the equilibrium distribution
predicted by string statistical mechanics. Analysis of the rate equation gives
results consistent with this. We then study the rate equation in an expanding
universe and suggest that three different final states are possible for the
evolving loop network, each of which may well be realised for some initial
conditions. If the initial energy density in loops in the radiation era is low,
then the loops rapidly disappear. For large initial energy densities, we expect
that either infinite strings are formed or that the loops tend towards a
scaling solution in the radiation era and then rapidly disappear in the matter
era. Such a scenario may be relevant given recent work highlighting the
problems with structure formation from the standard cosmic string scenario.Comment: LaTeX, 27 pages, 10 figures included as .eps file
An X-ray Spectral Survey of Radio-Loud AGN With ASCA
We present a uniform and systematic analysis of the 0.6-10 keV X-ray spectra
of radio-loud active galactic nuclei (AGN) observed by ASCA. The sample 10
BLRGs, 5 QSRs, 9 NLRGs, and 10 RGs. At soft X-rays, about half of the NLRGs and
all of the RGs exhibit a thermal plasma component, with a bimodal distribution
of temperatures and luminosities, suggesting an origin either in a surrounding
cluster or loose group or in a hot corona. At energies above 2 keV, a hard
power-law component is detected in 90% of cases. The power-law photon indices
and luminosities in BLRGs, QSRs, and NLRGs are similar, consistent with
orientation-based unification schemes. Significant excess cold absorption is
detected in most NLRGs, but also in some BLRGS and QSRs, which was somewhat
unexpected. In contrast to Seyfert galaxies, only one object showss the
signature of a warm absorber. The nuclear X-ray luminosity is correlated with
the luminosity of the [O III] emission line, the FIR emission at 12 microns,
and the lobe radio power at 5 GHz. The Fe K line is detected in 50% of BLRGs,
one QSR, and a handful of NLRGs. This sample also includes 6 Weak Line Radio
Galaxies (WLRGs). Their spectra WLRGs can be generally decomposed into a soft
thermal component with hard absrorbed power-law component, which is
significantly flatter than any other radio-loud AGNs. Their intrinsic
luminosities are two orders of magnitude lower than in other sources of the
sample. An interesting possibility is that WLRGs represent an extreme
population of radio galaxies in which the central black hole is accreting at a
rate well below the Eddington rate.Comment: To appear in the Astrophysical Journal. 72 pages, including many
tables and figures. Fig 1 is separate, in TIFF format. Postscript version of
fig 1 and postscript version of entire preprint can be obtained from
http://www.astro.psu.edu/users/mce/preprint_index.htm
The JCMT Gould Belt Survey: Evidence for radiative heating in Serpens MWC 297 and its influence on local star formation
We present SCUBA-2 450micron and 850micron observations of the Serpens MWC
297 region, part of the JCMT Gould Belt Survey of nearby star-forming regions.
Simulations suggest that radiative feedback influences the star-formation
process and we investigate observational evidence for this by constructing
temperature maps. Maps are derived from the ratio of SCUBA-2 fluxes and a two
component model of the JCMT beam for a fixed dust opacity spectral index of
beta = 1.8. Within 40 of the B1.5Ve Herbig star MWC 297, the submillimetre
fluxes are contaminated by free-free emission with a spectral index of
1.03+-0.02, consistent with an ultra-compact HII region and polar winds/jets.
Contamination accounts for 73+-5 per cent and 82+-4 per cent of peak flux at
450micron and 850micron respectively. The residual thermal disk of the star is
almost undetectable at these wavelengths. Young Stellar Objects are confirmed
where SCUBA-2 850micron clumps identified by the fellwalker algorithm coincide
with Spitzer Gould Belt Survey detections. We identify 23 objects and use Tbol
to classify nine YSOs with masses 0.09 to 5.1 Msun. We find two Class 0, one
Class 0/I, three Class I and three Class II sources. The mean temperature is
15+-2K for the nine YSOs and 32+-4K for the 14 starless clumps. We observe a
starless clump with an abnormally high mean temperature of 46+-2K and conclude
that it is radiatively heated by the star MWC 297. Jeans stability provides
evidence that radiative heating by the star MWC 297 may be suppressing clump
collapse.Comment: 24 pages, 13 figures, 7 table
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