14,748 research outputs found
Maximally Causal Quantum Mechanics
We present a new causal quantum mechanics in one and two dimensions developed
recently at TIFR by this author and V. Singh. In this theory both position and
momentum for a system point have Hamiltonian evolution in such a way that the
ensemble of system points leads to position and momentum probability densities
agreeing exactly with ordinary quantum mechanics.Comment: 7 pages,latex,no figures,to appear in Praman
The pion-pion scattering amplitude
We obtain reliable scattering amplitudes consistent with
experimental data, both at low and high energies, and fulfilling appropriate
analyticity properties. We do this by first fitting experimental low energy
() phase shifts and inelasticities with expressions
that incorporate analyticity and unitarity. In particular, for the S wave with
isospin~0, we discuss in detail several sets of experimental data. This
provides low energy partial wave amplitudes that summarize the known
experimental information. Then, we impose Regge behaviour as follows from
factorization and experimental data for the imaginary parts of the scattering
amplitudes at higher energy, and check fulfillment of dispersion relations up
to 0.925 GeV. This allows us to improve our fits. The ensuing
scattering amplitudes are then shown to verify dispersion relations up to 1.42
GeV, as well as crossing sum rules and other consistency
conditions. The improved parametrizations therefore provide a reliable
representation of pion-pion amplitudes with which one can test chiral
perturbation theory calculations, pionium decays, or use as input for
CP-violating decays. In this respect, we find
and
.Comment: Version to be published in Phys. Rev. D. Plain TeX file. (minor
changes). 16 figures (some multiple
Fifty Years of Economic Measurement: The Jubilee of the Conference on Research in Income and Wealth
Constraints on the Charged Higgs Sector from the Tevatron Collider Data on Top Quark Decay
The top quark data in the lepton plus channel offers a viable probe
for the charged Higgs boson signal. We analyse the recent Tevatron collider
data in this channel to obtain a significant limit on the mass in the
large region.Comment: 8 pages, LaTeX file; 2 figures included (PS files
Measurement of gut permeability using fluorescent tracer agent technology
Abstract The healthy gut restricts macromolecular and bacterial movement across tight junctions, while increased intestinal permeability accompanies many intestinal disorders. Dual sugar absorption tests, which measure intestinal permeability in humans, present challenges. Therefore, we asked if enterally administered fluorescent tracers could ascertain mucosal integrity, because transcutaneous measurement of differentially absorbed molecules could enable specimen-free evaluation of permeability. We induced small bowel injury in rats using high- (15 mg/kg), intermediate- (10 mg/kg), and low- (5 mg/kg) dose indomethacin. Then, we compared urinary ratios of enterally administered fluorescent tracers MB-402 and MB-301 to urinary ratios of sugar tracers lactulose and rhamnose. We also tested the ability of transcutaneous sensors to measure the ratios of absorbed fluorophores. Urinary fluorophore and sugar ratios reflect gut injury in an indomethacin dose dependent manner. The fluorophores generated smooth curvilinear ratio trajectories with wide dynamic ranges. The more chaotic sugar ratios had narrower dynamic ranges. Fluorophore ratios measured through the skin distinguished indomethacin-challenged from same day control rats. Enterally administered fluorophores can identify intestinal injury in a rat model. Fluorophore ratios are measureable through the skin, obviating drawbacks of dual sugar absorption tests. Pending validation, this technology should be considered for human use
Effective mobilities in pseudomorphic Si/SiGe/Si p-channel metal-oxide-semiconductor field-effect transistors with thin silicon capping layers
The room-temperature effective mobilities of pseudomorphic Si/Si0.64Ge0.36/Si p-metal-oxidesemiconductor field effect transistors are reported. The peak mobility in the buried SiGe channel increases with silicon cap thickness. It is argued that SiO2/Si interface roughness is a major source of scattering in these devices, which is attenuated for thicker silicon caps. It is also suggested that segregated Ge in the silicon cap interferes with the oxidation process, leading to increased SiO2/Si interface roughness in the case of thin silicon caps
Verbal Communication Skills Requirements for Information Systems Professionals
The role of information systems (IS) professionals in organizations has changed through the years, from one who works mostly with technically oriented peers, to one who spends a significant amount of time interacting with people who are involved in the functional areas of the organization. In many organizations, IS professionals are assigned permanently to the user area and they are expected to not only be technically competent, but also be competent in the user\u27s area. This move of IS professionals to the functional areas necessitates that they communicate more with the functional users whose IS needs they are fulfilling. The users, on the other hand, are also required to interact and communicate more with the IS people. With the move toward distributed IS, users are becoming more involved in the specification, design and sometimes even construction of their own systems. It is therefore imperative that analysts and users be able to communicate with each other unequivocally, so that the systems are specified and developed properly. This research investigated the verbal communication skills requirements for IS practicing professionals and new university graduates. A survey was used for data collection. It was sent to IS professionals in several large organizations, that represented the industry in general. A nearly perfect response rate was achieved. The findings are useful for both IS professionals and university programs. Organizations can use the findings to identify areas of weaknesses in the skills of their IS personnel and eliminate them with continuing education. Universities can use the findings to identify skills that they may not be currently emphasizing in their curricula and make necessary adjustments
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Antibiotic treatment triggers gut dysbiosis and modulates metabolism in a chicken model of gastro-intestinal infection
Background: Infection of the digestive track by gastro-intestinal pathogens results in the development of symptoms ranging from mild diarrhea to more severe clinical signs such as dysentery, severe dehydration and potentially death. Although, antibiotics are efficient to tackle infections, they also trigger dysbiosis that has been suggested to result in variation in weight gain in animal production systems. Results: Here is the first study demonstrating the metabolic impact of infection by a gastro-intestinal pathogen (Brachyspira pilosicoli) and its resolution by antibiotic treatment (tiamulin) on the host (chicken) systemic metabolism and gut microbiota composition using high-resolution 1H nuclear magnetic resonance (NMR) spectroscopy and 16S rDNA next generation sequencing (NGS). Clear systemic metabolic markers of infections such as glycerol and betaine were identified. Weight loss in untreated animals was in part explained by the observation of a modification of systemic host energy metabolism characterized by the utilization of glycerol as a glucose precursor. However, antibiotic treatment triggered an increased VLDL/HDL ratio in plasma that may contribute to reducing weight loss observed in treated birds. All metabolic responses co-occurred with significant shift of the microbiota upon infection or antibiotic treatment. Conclusion: This study indicates that infection and antibiotic treatment trigger dysbiosis that may impact host systemic energy metabolism and cause phenotypic and health modifications
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