944 research outputs found
Analysis of U.S. Senate Web Sites For Disability Accessibility
U.S. federal government web sites have increased significantly the level of services and information offered to various internal and external stakeholders. The Workforce Investment Act of 1998 amended Section 508 of the Rehabilitation Act of 1973, which complemented the intent and aims of the 1990 Americans with Disabilities Act (ADA). As a result, federal agencies and departments were mandated to provide disabled stakeholders with access to key information from federal web sites. However, since this enactment, some federal web sites still do not meet fully the legal requirements to accommodate users with disabilities. Additionally, web sites of members of the U.S. Congress technically do not fall under regulation. Without regulation, non-adherence to accessibility standards by congressional web sites may result in poor or ineffective utilization by citizen consumers or other stakeholders with disabilities. The purpose of this study is to examine the accessibility statistics for a pseudo-random sample of 50 web sites of U.S. Senators. The main web page of each site was evaluated with an online web site analysis software tool – Truwex. Three factors were used to gauge the level of accessibility: criteria based on Section 508, WCAG 1.0 standards, and WCAG 2.0 standards. Results suggest that the vast majority of the U.S. Senate web sites do not meet the federal legal guidelines that otherwise are imposed on other U.S. governmental agencies and departments. Many of the sites contain consistent patterns of non-compliance, and some minor changes could result in increased accessibility for disabled stakeholders
The Outer Envelopes of Globular Clusters. II. NGC 1851, NGC 5824 and NGC 1261
We present a second set of results from a wide-field photometric survey of
the environs of Milky Way globular clusters. The clusters studied are NGC 1261,
NGC 1851 and NGC 5824: all have data from DECam on the Blanco 4m telescope. NGC
5824 also has data from the Magellan Clay telescope with MegaCam. We confirm
the existence of a large diffuse stellar envelope surrounding NGC 1851 of size
at least 240 pc in radius. The radial density profile of the envelope follows a
power-law decline with index and the projected shape is
slightly elliptical. For NGC 5824 there is no strong detection of a diffuse
stellar envelope, but we find the cluster is remarkably extended and is similar
in size (at least 230 pc in radius) to the envelope of NGC 1851. A stellar
envelope is also revealed around NGC 1261. However, it is notably smaller in
size with radius 105 pc. The radial density profile of the envelope is
also much steeper with . We discuss the possible nature
of the diffuse stellar envelopes, but are unable to draw definitive conclusions
based on the current data. NGC 1851, and potentially NGC 5824, could be
stripped dwarf galaxy nuclei, akin to the cases of Cen, M54 and M2. On
the other hand, the different characteristics of the NGC 1261 envelope suggest
that it may be the product of dynamical evolution of the cluster.Comment: 18 pages, 11 figures, accepted to MNRA
Bactericidal peptidoglycan recognition protein induces oxidative stress in Escherichia coli through a block in respiratory chain and increase in central carbon catabolism
Mammalian Peptidoglycan Recognition Proteins (PGRPs) kill both Gram-positive and Gram-negative bacteria through simultaneous induction of oxidative, thiol and metal stress responses in bacteria. However, metabolic pathways through which PGRPs induce these bactericidal stress responses are unknown. We screened Keio collection of Escherichia coli deletion mutants and revealed that deleting genes for respiratory chain flavoproteins or for tricarboxylic acid (TCA) cycle resulted in increased resistance of E. coli to PGRP killing. PGRP-induced killing depended on the production of hydrogen peroxide, which required increased supply of NADH for respiratory chain oxidoreductases from central carbon catabolism (glycolysis and TCA cycle), and was controlled by cAMP-Crp. Bactericidal PGRP induced a rapid decrease in respiration, which suggested that the main source of increased production of hydrogen peroxide was a block in respiratory chain and diversion of electrons from NADH oxidoreductases to oxygen. CpxRA two-component system was a negative regulator of PGRP-induced oxidative stress. By contrast, PGRP-induced thiol stress (depletion of thiols) and metal stress (increase in intracellular free Zn2+ through influx of extracellular Zn2+ ) were mostly independent of oxidative stress. Thus, manipulating pathways that induce oxidative, thiol and metal stress in bacteria could be a useful strategy to design new approaches to antibacterial therapy
The Tanzanian Trauma patients' Prehospital Experience: A Qualitative Interview-based Study.
We sought to characterise the prehospital experience of Tanzanian trauma patients, and identify barriers and facilitators to implement community-based emergency medical systems (EMS). Our study was conducted in the emergency department of an urban national referral hospital in Tanzania. A convenience sample of 34 adult trauma patients, or surrogate family members, presenting or referred to an urban referral emergency department in Tanzania for treatment of injury, participated in the study. Participation in semistructured, iteratively developed interviews until saturation of responses was reached. A grounded theory-based approach to qualitative analysis was used to identify recurrent themes. We characterised numerous deficiencies within the existing clinic-to-hospital referral network, including missed/delayed diagnoses, limited management capabilities at pre-referral facilities and interfacility transfer delays. Potential barriers to EMS implementation include patient financial limitations and lack of insurance, limited public infrastructure and resources, and the credibility of potential first aid responders. Potential facilitators of EMS include communities' tendency to pool resources, individuals' trust of other community members to be first aid responders, and faith in community leaders to organise EMS response. Participants expressed a strong desire to learn first aid. The composite themes generated by the data suggest that there are myriad structural, financial, institutional and cultural barriers to the implementation of a formal prehospital system. However, our analysis also revealed potential facilitators to a first-responder system that takes advantage of close-knit local communities and the trust of recognised leaders in society. The results suggest favourable acceptability for community-based response by trained lay people. There is significant opportunity for care improvements with short trainings and low-cost supply planning. Further research looking at the effects of delay on outcomes in this population is needed
Nuclear Spin Relaxation for Higher Spin
We study the relaxation of a spin I that is weakly coupled to a quantum
mechanical environment. Starting from the microscopic description, we derive a
system of coupled relaxation equations within the adiabatic approximation.
These are valid for arbitrary I and also for a general stationary
non--equilibrium state of the environment. In the case of equilibrium, the
stationary solution of the equations becomes the correct Boltzmannian
equilibrium distribution for given spin I. The relaxation towards the
stationary solution is characterized by a set of relaxation times, the longest
of which can be shorter, by a factor of up to 2I, than the relaxation time in
the corresponding Bloch equations calculated in the standard perturbative way.Comment: 4 pages, Latex, 2 figure
Spectroscopic Evidence for the Localization of Skyrmions near Nu=1 as T->0
Optically pumped nuclear magnetic resonance measurements of Ga-71 spectra
were carried out in an n-doped GaAs/Al0.1Ga0.9As multiple quantum well sample
near the integer quantum Hall ground state Nu=1. As the temperature is lowered
(down to T~0.3 K), a ``tilted plateau'' emerges in the Knight shift data, which
is a novel experimental signature of quasiparticle localization. The dependence
of the spectra on both T and Nu suggests that the localization is a collective
process. The frozen limit spectra appear to rule out a 2D lattice of
conventional skyrmions.Comment: 4 pages (REVTEX), 5 eps figures embedded in text, published versio
Self-consistent propagation of flux ropes in realistic coronal simulations
The aim of this paper is to demonstrate the possible use of the new coronal
model COCONUT to compute a detailed representation of a numerical CME at
0.1~AU, after its injection at the solar surface and propagation in a realistic
solar wind, as derived from observed magnetograms. We present the
implementation and propagation of modified Titov-D\'emoulin (TDm) flux ropes in
the COCONUT 3D MHD coronal model. The background solar wind is reconstructed in
order to model two opposite configurations representing a solar activity
maximum and minimum respectively. Both were derived from magnetograms which
were obtained by the Helioseismic and Magnetic Imager (HMI) onboard the Solar
Dynamic Observatory (SDO) satellite. We track the propagation of 24 flux ropes,
which differ only by their initial magnetic flux. We especially investigate the
geometry of the flux rope during the early stages of the propagation as well as
the influence of its initial parameters and solar wind configuration on 1D
profiles derived at 0.1~AU. At the beginning of the propagation, the shape of
the flux ropes varies between simulations during low and high solar activity.
We find dynamics that are consistent with the standard CME model, such as the
pinching of the legs and the appearance of post-flare loops. Despite the
differences in geometry, the synthetic density and magnetic field time profiles
at 0.1~AU are very similar in both solar wind configurations. These profiles
are similar to those observed further in the heliosphere and suggest the
presence of a magnetic ejecta composed of the initially implemented flux rope
and a sheath ahead of it. Finally, we uncover relationships between the
properties of the magnetic ejecta, such as density or speed and the initial
magnetic flux of our flux ropes.Comment: 20 pages, 13 figure
Asymmetric transfer hydrogenation of imines and ketones using chiral Ru(II)Cl(η6-p-cymene)[(S,S)-N-TsDPEN] catalyst: a computational study
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