18,534 research outputs found
Stable ac phase and amplitude comparator
Stable ac phase and amplitude comparator detects excessive vehicle maneuvering or vibration. It has phase demodulation, low-pass filter, and multiple threshold-setting capability designed specifically for low drifts over a wide range of temperatures
Electromagnetic Deflection of Spinning Particles
We show that it is possible to obtain self-consistent and physically
acceptable relativistic classical equations of motion for a point-like
spin-half particle possessing an electric charge and a magnetic dipole moment,
directly from a manifestly covariant Lagrangian, if the classical degrees of
freedom are appropriately chosen. It is shown that the equations obtained
encompass the well-tested Lorentz force and Thomas--Bargmann--Michel--Telegdi
spin equations, as well as providing a definite specification of the classical
_magnetic_dipole_ force_, whose exact form has been the subject of recent
debate. Radiation reaction---the force and torque on an accelerated particle
due to its self-interaction---is neglected at this stage.Comment: 18 pp. (latex, uses revtex 3), UM-P-92/9
The Foldy-Wouthuysen transformation
The Foldy-Wouthuysen transformation of the Dirac Hamiltonian is generally
taught as simply a mathematical trick that allows one to obtain a two-component
theory in the low-energy limit. It is not often emphasized that the transformed
representation is the only one in which one can take a meaningful *classical
limit*, in terms of particles and antiparticles. We briefly review the history
and physics of this transformation.Comment: Standard LaTeX, 6 page
Zoonotic potential of Salmonella enterica carried by pet tortoises
The prevalence of Salmonella in chelonians is not known in the UK and it is not clear whether such Salmonella strains would be pathogenic for human beings. Some strains, such as members of the Arizonae subgroup, may be unable to cause anything more than very mild disease. To determine the carriage of Salmonella in pet tortoises, cloacal swabs were taken for culture. Salmonella enterica Group D was isolated from 5 of the 89 samples. All five were from the same household of seven tortoises. Salmonella isolates were shown by PCR to carry the invA and spiC genes associated with pathogenicity islands 1 and 2. Each isolate carried both genes indicating they had the genetic basis for disease and enterocyte invasion in human beings. The study indicates a low rate of asymptomatic carriage among the general population of pet tortoises. However, it does suggest that those Salmonella strains colonising the tortoise can carry Salmonella pathogenicity island (SPI)-1 and SPI-2 conferring the potential to cause disease in human beings and other animals
Difficult to Show Properties and Utility Maximizing Brokers
This article is the winner of the Real Estate and the Internet manuscript prize (sponsored by PricewaterhouseCoopers) presented at the American Real Estate Society Annual Meeting. Brokers have long believed that difficult to show properties sell at lower prices and take longer to sell. Where difficult to show properties are defined as those properties that present extraordinary difficulties for a broker in arranging or showing the listing to a particular buyer. Buyersâ recent access to online real estate applications may make the cost of avoiding these properties prohibitive to brokers. Employing a hedonic pricing model and duration modeling techniques, this study finds that property price and marketing time are not significantly affected for these properties. The results suggest that brokers possess limited market power.
Double-stranded RNA elements associated with the MVX disease of Agaricus bisporus
Double-stranded RNA (dsRNA) has been isolated from Agaricus bisporus fruit bodies exhibiting a wide range of disease symptoms. The symptoms which occurred singularly or in combination included; bare cropping areas on commercial beds (primordia disruption), crop delay, premature veil opening, off- or brown-coloured mushrooms, sporophore malformations and loss of crop yield. All symptoms were associated with loss of yield and/or product quality. Collectively, these symptoms are described as mushroom virus X (MVX) disease. The dsRNA titre was much lower than that previously encountered with the La France viral disease of mushrooms and a modified cellulose CF11 protocol was used for their detection. A broad survey of cultivated mushrooms from the British industry identified dsRNA elements ranging between 640 bp and 20.2 kbp; the majority have not previously been described in A. bisporus. 26 dsRNA elements were identified with a maximum of 17, apparently non-encapsidated dsRNA elements, in any one sample. Three dsRNAs (16.2, 9.4 and 2.4 kbp) were routinely found in mushrooms asymptomatic for MVX. Previously, La France disease was effectively contained and controlled by minimising the on-farm production and spread of basidiospores. Our on-farm observations suggest that MVX could be spread by infected spores and/or mycelial fragments
Construction and analysis of a simplified many-body neutrino model
In dense neutrino systems, such as found in the early Universe, or near a
supernova core, neutrino flavor evolution is affected by coherent
neutrino-neutrino scattering. It has been recently suggested that many-particle
quantum entanglement effects may play an essential role in these systems,
potentially invalidating the traditional description in terms of a set of
single-particle evolution equations. We model the neutrino system by a system
of interacting spins, following an earlier work which showed that such a spin
system can in some cases be solved exactly. We extend this work by constructing
an exact analytical solution to a more general spin system, including initial
states with asymmetric spin distribution and, moreover, not necessarily aligned
along the same axis. Our solution exhibits a rich set of behaviors, including
coherent oscillations and dephasing and a transition from the classical to
quantum regimes. We argue that the classical evolution of the spin system
captures the entire coherent behavior of the neutrino system, while the quantum
effects in the spin system capture some, but not all, of the neutrino
incoherent evolution. By comparing the spin and neutrino systems, we find no
evidence for the violation of the accepted one-body description, though the
argument involves some subtleties not appreciated before. The analysis in this
paper may apply to other two-state systems beyond the neutrino field.Comment: 22 pages, 7 figure
Computerized system for translating a torch head
The system provides a constant travel speed along a contoured workpiece. It has a driven skate characterized by an elongated bed, with a pair of independently pivoted trucks connected to the bed for support. The trucks are mounted on a contoured track of arbitrary configuration in a mutually spaced relation. An axially extensible torch head manipulator arm is mounted on the bed of the carriage and projects perpendicular from the midportion. The torch head is mounted at its distal end. A real-time computerized control drive subsystem is used to advance the skate along the track of a variable rate for maintaining a constant speed for the torch head tip, and to position the torch axis relative to a preset angle to the workpiece
Chief Justice Ralph J. Cappy\u27s Death Penalty Dissents: The Important of Statutory Authority and Procedural Protections
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