6,039 research outputs found
Coloured worker in British industry: with special reference to the Midlands and North of England
The detection and photometric redshift determination of distant galaxies using SIRTF's Infrared Array Camera
We investigate the ability of the Space Infrared Telescope Facility's
Infrared Array Camera to detect distant (z ~ 3)galaxies and measure their
photometric redshifts. Our analysis shows that changing the original long
wavelength filter specifications provides significant improvements in
performance in this and other areas.Comment: 28 pages incl 12 figures; to appear in June 1999 PASP. Fig.12
replaced with corrected versio
The Pathology of Methanogenic Archaea in Human Gastrointestinal Tract Disease
Methane-producing archaea have recently been associated with disorders of the gastrointestinal tract and dysbiosis of the resident microbiota. Some of these conditions include inflammatory bowel disease (Crohn’s disease (CD) and ulcerative colitis (UC)), chronic constipation, small intestinal bacterial overgrowth, gastrointestinal cancer, anorexia, and obesity. The causal relationship and the putative mechanism by which archaea may be associated with human disease are poorly understood, as are the strategies to alter methanogen populations in humans. It is estimated that 30–62% of humans produce methane detectable in exhaled breath and in the gastrointestinal tract. However, it is not yet known what portion of the human population have detectable methanogenic archaea. Hydrogen and methane are often measured in the breath as clinical indicators of intolerance to lactose and other carbohydrates. Breath gas analysis is also employed to diagnose suspected small intestinal bacterial overgrowth and irritable bowel syndrome, although standards are lacking. The diagnostic value for breath gas measurement in human disease is evolving; therefore, standardized breath gas measurements combined with ever-improving molecular methodologies could provide novel strategies to prevent, diagnose, or manage numerous colonic disorders. In cases where methanogens are potentially pathogenic, more data are required to develop therapeutic antimicrobials or other mitigation strategies
Spin-resolved electron waiting times in a quantum dot spin valve
We study the electronic waiting time distributions (WTDs) in a
non-interacting quantum dot spin valve by varying spin polarization and the
noncollinear angle between the magnetizations of the leads using scattering
matrix approach. Since the quantum dot spin valve involves two channels (spin
up and down) in both the incoming and outgoing channels, we study three
different kinds of WTDs, which are two-channel WTD, spin-resolved
single-channel WTD and cross-channel WTD. We analyze the behaviors of WTDs in
short times, correlated with the current behaviors for different spin
polarizations and noncollinear angles. Cross-channel WTD reflects the
correlation between two spin channels and can be used to characterize the spin
transfer torque process. We study the influence of the earlier detection on the
subsequent detection from the perspective of cross-channel WTD, and define the
influence degree quantity as the cumulative absolute difference between
cross-channel WTDs and first passage time distributions to quantitatively
characterize the spin flip process. The influence degree shows a similar
behavior with spin transfer torque and can be a new pathway to characterize
spin correlation in spintronics system.Comment: 9 pages, 7 figure
Improved statistical methods for estimating infestation rates in quarantine research when hosts are naturally infested
Trading partners often require phytosanitary or quarantine treatments for fresh horticultural produce to ensure no economically important pest species are moved with the imported product. When developing such treatments, it is essential that the level of treatment efficacy can be determined. This is often based on the mortality of the total number of target pests exposed to treatment, but in naturally infested products this number is not always known. In such cases, the infestation rate and subsequently an estimate of the number of pests are obtained directly from a set of untreated control samples of the host product. The International Plant Protection Convention (IPPC) Secretariat has provided 2 formulas for these situations that place an interval around the point estimate obtained from the control samples to obtain an estimate of the infestation rate. However, these formulas do not allow a confidence level to be assigned to the estimate, and there are concerns with the assumptions regarding the distribution and the measure of variability used in the formulas. In this article, we propose 2 alternative formulas. We propose that the lower one-sided confidence limit should be applied to all infestation datasets that are approximately normally distributed. As infestation data are sometimes skewed, it is proposed the lower one-sided modified Cox confidence limit is applied to data approximately log-normal distributed. These well-recognized formulas are compared to the formulas recommended by the IPPC and applied to 3 datasets involving natural infestation
Early CRT monitoring using time-domain optical coherence tomography does not add to visual acuity for predicting visual loss in patients with central retinal vein occlusion treated with intravitreal ranibizumab:A secondary analysis of trial data
Our primary purpose was to assess the clinical (predictive) validity of central retinal thickness (CRT) and best corrected visual acuity (BCVA) at 1 week and 1 month after starting treatment with ranibizumab for central retinal vein occlusion. The authors also assessed detectability of response to treatment
WISE Brown Dwarf Binaries: The Discovery of a T5+T5 and a T8.5+T9 System
The multiplicity properties of brown dwarfs are critical empirical constraints for formation theories, while multiples themselves provide unique opportunities to test evolutionary and atmospheric models and examine empirical trends. Studies using high-resolution imaging cannot only uncover faint companions, but they can also be used to determine dynamical masses through long-term monitoring of binary systems. We have begun a search for the coolest brown dwarfs using preliminary processing of data from the Wide-field Infrared Survey Explorer and have confirmed many of the candidates as late-type T dwarfs. In order to search for companions to these objects, we are conducting observations using the Laser Guide Star Adaptive Optics system on Keck II. Here we present the first results of that search, including a T5 binary with nearly equal mass components and a faint companion to a T8.5 dwarf with an estimated spectral type of T9
The hardware is the software
Human brains and bodies are not hardware running software: the hardware is
the software. We reason that because the microscopic physics of
artificial-intelligence hardware and of human biological "hardware" is
distinct, neuromorphic engineers need to be cautious (and yet also creative) in
how we take inspiration from biological intelligence. We should focus primarily
on principles and design ideas that respect -- and embrace -- the underlying
hardware physics of non-biological intelligent systems, rather than abstracting
it away. We see a major role for neuroscience in neuromorphic computing as
identifying the physics-agnostic principles of biological intelligence -- that
is the principles of biological intelligence that can be gainfully adapted and
applied to any physical hardware
Safety Program at the Nuclear Rocket Development Station
Many unique problems have been encountered and overcome in the developmental testing of nuclear powered engines for space applications, necessitating an extensive radiological and cryogenic safety program at the Nuclear Rocket Development Station. (NRDS) The radiological safety program directs itself toward the protection of personnel associated with the program and the public from direct radiation and resultant radioactive effluent. The cryogenics safety program at the NRDS directs itself to the prevention of accidents which could damage the nuclear reactor or the test facilities and in turn endanger associated personnel. It is graphically illustrated that nuclear rocket engines do not present a radiological safety problem prior to operation, and that during and following operation, experience has proven that control measures are possible to minimize possible hazards. Of particular interest is the comparison of cryogenic and radiological safety effects
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