1,316 research outputs found
For how long do people with osteoarthritis self-manage before seeking physician care? Survey on living with chronic diseases in Canada findings
CHANDRA Observations of X-ray Jet Structure on kpc to Mpc Scales
With its exquisite spatial resolution of better than 0.5 arcsecond, the
Chandra observatory is uniquely capable of resolving and studying the spatial
structure of extragalactic X-ray jets on scales of a few to a few hundred
kilo-parsec. Our analyses of four recent Chandra images of quasar jets
interpret the X-ray emission as inverse Compton scattering of high energy
electrons on the cosmic microwave background. We infer that these jets are in
bulk relativistic motion, carrying kinetic powers upwards of 10^46 ergs/s to
distances of hundreds of kpc, with very high efficiency.Comment: 4 pages, 3 figures, to be published in the proceedings of the Bologna
jet workshop, "The Physics of Relativistic Jets in the CHANDRA and XMM Era.
372 DETERMINING PATTERNS OF RADIOGRAPHIC HAND OSTEOARTHRITIS IN A COMMUNITY-DWELLING POPULATION OF ADULTS AGED 50 YEARS AND OVER USING FACTOR ANALYSIS
Surface Morphology and Microstructure of Al-O Alloys Grown by ECR Plasma Deposition
The growth of polycrystalline and amorphous aluminum-oxygen alloy films using electron-beam evaporation of Al in the presence of an O{sub 2} electron-cyclotron-resonance (ECR) plasma was investigated for film compositions varying from 40% Al (Al{sub 2}O{sub 3}) to near 100% Al (AlO{sub x}). Processing parameters such as deposition temperature and ion energy were varied to study their effects on surface texture and film microstructure. The Al-rich films (AlO{sub x}) contain polycrystalline fcc Al grains with finely dispersed second-phase particles of {gamma}-Al{sub 2}O{sub 3} (1-2 nm in size). The surface roughness of these films was measured by atomic force microscopy and found to increase with sample bias and deposition temperature. Stoichiometric Al{sub 2}O{sub 3} films grown at 100{degrees}C and 400{degrees}C without an applied bias were amorphous, while an applied bias of -140 V formed a nanocrystalline {gamma}-Al{sub 2}O{sub 3} film at 400{degrees}C. The surface roughness of the Al{sub 2}O{sub 3} increased with temperature while ion irradiation produced a smoother surface
Effective Hamiltonian for non-minimally coupled scalar fields
Performing a relativistic approximation as the generalization to a curved
spacetime of the flat space Klein-Gordon equation, an effective Hamiltonian
which includes non-minimial coupling between gravity and scalar field and also
quartic self-interaction of scalar field term is obtained.Comment: 4 page
THE AMUNDSEN SEA LOW Variability, Change, and Impact on Antarctic Climate
The Amundsen Sea low (ASL) is a climatological low pressure center that exerts considerable influence on the climate of West Antarctica. Its potential to explain important recent changes in Antarctic climate, for example, in temperature and sea ice extent, means that it has become the focus of an increasing number of studies. Here, the authors summarize the current understanding of the ASL, using reanalysis datasets to analyze recent variability and trends, as well as ice-core chemistry and climate model projections, to examine past and future changes in the ASL, respectively. The ASL has deepened in recent decades, affecting the climate through its influence on the regional meridional wind field, which controls the advection of moisture and heat into the continent. Deepening of the ASL in spring is consistent with observed West Antarctic warming and greater sea ice extent in the Ross Sea. Climate model simulations for recent decades indicate that this deepening is mediated by tropical variability while climate model projections through the twenty-first century suggest that the ASL will deepen in some seasons in response to greenhouse gas concentration increases
Study of a Large NaI(Tl) Crystal
Using a narrow band positron beam, the response of a large high-resolution
NaI(Tl) crystal to an incident positron beam was measured. It was found that
nuclear interactions cause the appearance of additional peaks in the low energy
tail of the deposited energy spectrum
High Purity Pion Beam at TRIUMF
An extension of the TRIUMF M13 low-energy pion channel designed to suppress
positrons based on an energy-loss technique is described. A source of beam
channel momentum calibration from the decay pi+ --> e+ nu is also described.Comment: 5 page
Detecting fractions of electrons in the high- cuprates
We propose several tests of the idea that the electron is fractionalized in
the underdoped and undoped cuprates. These include the ac Josephson effect, and
tunneling into small superconducting grains in the Coulomb blockade regime. In
both cases, we argue that the results are qualitatively modified from the
conventional ones if the insulating tunnel barrier is fractionalized. These
experiments directly detect the possible existence of the chargon - a charge
spinless boson - in the insulator. The effects described in this paper
provide a means to probing whether the undoped cuprate (despite it's magnetism)
is fractionalized. Thus, the experiments discussed here are complementary to
the flux-trapping experiment we proposed in our earlier work(cond-mat/0006481).Comment: 7 pages, 5 figure
X-Ray Scattering Measurements of the Transient Structure of a Driven Charge-Density-Wave
We report time-resolved x-ray scattering measurements of the transient
structural response of the sliding {\bf Q} charge-density-wave (CDW) in
NbSe to a reversal of the driving electric field. The observed time scale
characterizing this response at 70K varies from 15 msec for driving
fields near threshold to 2 msec for fields well above threshold. The
position and time-dependent strain of the CDW is analyzed in terms of a
phenomenological equation of motion for the phase of the CDW order parameter.
The value of the damping constant, eV
seconds \AA, is in excellent agreement with the value
determined from transport measurements. As the driving field approaches
threshold from above, the line shape becomes bimodal, suggesting that the CDW
does not depin throughout the entire sample at one well-defined voltage.Comment: revtex 3.0, 7 figure
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