53,073 research outputs found
Community-Based Exercise Education During Colder Months
Approximately 50% of US adults and 75% of US high school students don\u27t meet recommended weekly physical activity guidelines, and physical activity declines further during colder seasons. Resources describing local suggestions for physical activity should be made broadly available to community members, such as at their primary health care office.https://scholarworks.uvm.edu/fmclerk/1514/thumbnail.jp
Modelling the redshift-space distortion of galaxy clustering
We use a set of large, high-resolution cosmological N-body simulations to
examine the redshift-space distortions of galaxy clustering on scales of order
10-200h^{-1} Mpc. Galaxy redshift surveys currently in progress will, on
completion, allow us to measure the quadrupole distortion in the 2-point
correlation function, \xi(\sigma,\pi), or its Fourier transform, the power
spectrum, P(k,\mu), to a high degree of accuracy. On these scales we typically
find a positive quadrupole, as expected for coherent infall onto overdense
regions and outflow from underdense regions, but the distortion is
substantially weaker than that predicted by pure linear theory. We assess two
models that may be regarded as refinements to linear theory, the Zel'dovich
approximation and a dispersion model in which the non-linear velocities
generated by the formation of virialized groups and clusters are treated as
random perturbations to the velocities predicted by linear theory. We find that
neither provides an adequate physical description of the clustering pattern. If
used to model redshift spacedistortions on scales for 10<\lambda <200 h^{-1}Mpc
the estimated value of \beta (\beta=f(\Omega_0)/b where f(\Omega_0) ~
\Omega_0^{0.6} and b is the galaxy bias parameter) is liable to systematic
errors of order ten per cent or more. We discuss how such systematics can be
avoided by i) development of a more complete model of redshift distortions and
ii) the direct use of galaxy catalogues generated from non-linear N-body
simulations.Comment: 13 pages, Latex, uses mn.sty and mnextra.sty (mnextra.sty included
here
Exploratory flutter test in a cryogenic wind tunnel
A model consisting of a rigid wing with an integral, flexible beam support that was cantilever mounted from the wall in the NASA LaRC 0.3-m transonic cryogenic tunnel was used in a flutter analysis study. The wing had a rectangular planform of aspect ratio 1.5 and a 64A010 airfoil. Various considerations and procedures for conducting flutter tests in a cryogenic wind tunnel were evaluated. Flutter onset conditions were established from extrapolated subcritical response measurements. A flutter boundary was determined at cryogenic temperatures over a Mach number M range from 0.5 to 0.9. Flutter was obtained at two different Reynolds numbers R at M = 0.5 (R = 4.4 and 18.4 x 10 to the 6th power) and at M = 0.8 (R = 5.0 and 10.4 x 10 to the 6th power). Flutter analyses using subsonic lifting surface (kernel function) aerodynamics were made over the range of test conditions. To evaluate the Reynolds number effects at M = 0.5 and 0.8, the experimental results were adjusted using analytical trends to account for differences in the model test temperatures and mass ratios. The adjusted experimental results indicate that increasing Reynolds number from 5.0 to 20.0 x 10 to the 6th power decreased the dynamic pressure by 4.0 to 6.5 percent at M = 0.5 and 0.8
The National Security Agency\u27s Domestic Spying Program: Framing the Debate
On Friday, December 16, 2005, the New York Times reported that President George W. Bush had secretly authorized the National Security Agency (NSA) to conduct warrantless surveillance of Americans\u27 telephone and e-mail communications as part of an effort to obtain intelligence about future terrorist activity.\u27 The Times report was based on leaks of classified information, presumably by NSA officials concerned about the legality of the program. The Times reported that at the President\u27s request it had delayed publication of the story for more than a year.
The Indiana Law Journal reprinted four documents that, taken together, set forth the basic arguments concerning the lawfulness of the secret NSA surveillance program. The debate outlined by the four documents raises important issues about statutory interpretation in the face of claims of constitutional conflict, executive power during times of war, fundamental privacy rights of Americans, and ultimately, the rule of law in the war on terror
Divergence study of a high-aspect ratio, forward-swept wing
An experimental wind-tunnel study to determine the divergence characteristics of a high-aspect ratio, forward-swept wing has been conducted in the NASA Langley Research Center (LaRC) Transonic Dynamics Tunnel (TDT). The rectangular wing used for this study had a panel aspect ratio of 9.16 (lambda = 0 deg.) and the sweep angle could be set at lambda = 0 deg., -15 deg., -30 deg., -45 deg., or -60 deg. A rectangular wing tip shape was tested at each of these sweep angles. In addition, a tip shape parallel to the freestream flow was tested for a wing sweep angle of lambda = -45 deg. The root of the wing was cantilever mounted to the wall of the wind tunnel. Divergence conditions were measured at M = 0.4 for each sweep angle and tip configuration tested. Subcritical response techniques were used to extrapolate to the divergence conditions during the wind-tunnel test. The primary objective of this test was to obtain data which could be used to verify for this configuration the divergence prediction capability of an aeroelastic analysis code. Subsonic lifting surface theory (kernel function) aerodynamics are utilized by this particular code. The analytical predictions of divergence were found to be significantly conservative at all forward sweep angles. At lambda = -45 deg., the analysis was 14 percent conservative. The effect of the two tip shapes on the divergence dynamic pressure was predicted accurately by the analysis. The divergence condition for the tip shape parallel to the flow occurred at a dynamic pressure 14 percent higher than the divergence condition with a rectangular tip shape
Faint counts as a function of morphological type in a hierarchical merger model
The unprecedented resolution of the refurbished Wide Field and Planetary
Camera 2 (WFPC2) on the Hubble Space Telescope (HST) has led to major advances
in our understanding of galaxy formation. The high image quality in the Medium
Deep Survey and Hubble Deep Field has made it possible, for the first time, to
classify faint distant galaxies according to morphological type. These
observations have revealed a large population of galaxies classed as irregulars
or which show signs of recent merger activity. Their abundance rises steeply
with apparent magnitude, providing a likely explanation for the large number of
blue galaxies seen at faint magnitudes. We demonstrate that such a population
arises naturally in a model in which structure forms hierarchically and which
is dynamically dominated by cold dark matter. The number counts of irregular,
spiral and elliptical galaxies as a function of magnitude seen in the HST data
are well reproduced in this model.We present detailed predictions for the
outcome of spectroscopic follow-up observations of the HST surveys. By
measuring the redshift distributions of faint galaxies of different
morphological types, these programmes will provide a test of the hierarchical
galaxy formation paradigm and might distinguish between models with different
cosmological parameters.Comment: 5 pages, 3 postscript figures included. To be published as a Letter
in Monthly Notices of the RAS. Postscript version available at
http://star-www.dur.ac.uk/~cmb/counts.htm
Inorganic glass ceramic slip rings
Prototypes of slip rings have been fabricated from ceramic glass, a material which is highly resistant to deterioration due to high temperature. Slip ring assemblies were not structurally damaged by mechanical tests and performed statisfactorily for 200 hours
The blue one takes a battering why do young adults with asthma overuse bronchodilator inhalers? A qualitative study
Objective: Overuse of short-acting bronchodilators is internationally recognised as a marker of poor asthma control, high healthcare use and increased risk of asthma death. Young adults with asthma commonly overuse short-acting bronchodilators. We sought to determine the reasons for overuse of bronchodilator inhalers in a sample of young adults with asthma. Design: Qualitative study using a purposive extreme case sample. Setting: A large urban UK general practice. Participants: Twenty-one adults with moderate asthma, aged 20-32 years. Twelve were high users of short-acting bronchodilators, nine were low users. Results: Asthma had a major impact on respondents' lives, disrupting their childhood, family life and career opportunities. High users of short-acting bronchodilators had adapted poorly to having asthma and expressed anger at the restrictions they experienced. Overuse made sense to them: shortacting bronchodilators were a rapid, effective, cheap 'quick-fix' for asthma symptoms. High users had poorer control of asthma and held explanatory models of asthma which emphasised short-term relief via bronchodilation over prevention. Both high and low users held strong views about having to pay for asthma medication, with costs cited as a reason for not purchasing anti-inflammatory inhalers. Conclusions: Young adults who were high users of short-acting bronchodilators had adapted poorly to having asthma and had poor asthma control. They gave coherent reasons for overuse. Strategies that might address high bronchodilator use in young adults include improving education to help young people accept and adapt to their illness, reducing stigmatisation and providing free asthma medication to encourage the use of anti-inflammatory inhalers
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More than Words: The Impact of Memory on How Undergraduates with Dyslexia Interact with Information
Despite the prevalence of dyslexia and the challenges it poses for seeking, assessing and using information, there has been relatively little research on the challenges people with dyslexia face when interacting with information. What existing research there is has mostly focused on the impact on information comprehension and spelling. However, people with dyslexia often face considerable memory impairment that can affect their learning. This paper reports findings from retrospective think-aloud (RTA) observations with 13 undergraduates with dyslexia, focusing on the memory-related barriers they face and the workarounds they use to overcome these barriers. An enhanced understanding of the full range of barriers faced by information-seekers with dyslexia can inform the design of dyslexia-aware digital information environments and information literacy programs. These can ‘level the information playing field’ by helping to break down barriers to information and, in turn, to knowledge creation
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