5,316 research outputs found
Microwave diode amplifiers with low intermodulation distortion
Distortions can be greatly reduced in narrow-band applications by using the second harmonic. The ac behavior of simplified diode amplifier has negative resistance depending on slope of equivalent I-V curve
Cavity QED determination of atomic number statistics in optical lattices
We study the reflection of two counter-propagating modes of the light field
in a ring resonator by ultracold atoms either in the Mott insulator state or in
the superfluid state of an optical lattice. We obtain exact numerical results
for a simple two-well model and carry out statistical calculations appropriate
for the full lattice case. We find that the dynamics of the reflected light
strongly depends on both the lattice spacing and the state of the matter-wave
field. Depending on the lattice spacing, the light field is sensitive to
various density-density correlation functions of the atoms. The light field and
the atoms become strongly entangled if the latter are in a superfluid state, in
which case the photon statistics typically exhibit complicated multimodal
structures.Comment: 10 pages revtex, 13 figure
Possible production of exotic baryonia in relativistic heavy-ion collisions
Properties of a hypothetical baryonium with the quark content
(uds\ov{u}\ov{d}\ov{s}) are discussed. The MIT bag model predicts its mass to
be unexpectedly low, approximately 1210 MeV. Possible hadronic decay modes of
this state are analyzed. Ultrarelativistic heavy-ion collisions provide
favorable conditions for the formation of such particles from the baryon-free
quark-gluon plasma. We estimate multiplicities of such exotic baryonia on the
basis of a simple thermal model.Comment: 8 pages, 1 figur
Using Birdsfoot Trefoil in Kentucky Pastures
Birdsfoot trefoil (Lotus corniculatus L.) is an excellent pasture legume in the Corn Belt and in northeast United states . It has usually been considered too poorly adapted to Kentucky to merit trial by the farmers. Observations and grazing results in Woodford county during the last 14 years, however, indicate that this view is no longer valid.
A grazing trial was established in 1954, with birdsfoot trefoil and Kentucky bluegrass as one of three mixtures used. Trefoil was seeded alone in the spring, and an excellent stand was obtained. Bluegrass was drilled in the established trefoil in September 1954. There were four 4-acre experimental pastures of trefoil-bluegrass and an additional 6-acre field which was used as a reserve pasture
A Nuclear Fragmentation Energy Deposition Model
A formalism for target fragment transport is presented with application to energy loss spectra in thin silicon devices. A nuclear database is recommended that agrees well with the measurements of P.J. McNulty et al. (1980) using surface barrier detectors. High-energy events observed by P.J. McNulty et al. (1981), which are not predicted by intranuclear cascade models, are well represented by this wor
Topographic controls on dike injection in volcanic rift zones
Author Posting. © Elsevier B.V., 2006. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Earth and Planetary Science Letters 246 (2006): 188-196, doi:10.1016/j.epsl.2006.04.005.Dike emplacement in volcanic rift zones is often associated with the injection of “bladelike”
dikes, which propagate long distances parallel to the rift, but frequently remain
trapped at depth and erupt only near the tip of the dike. Over geologic time, this style of
dike injection implies that a greater percentage of extension is accommodated by magma
accretion at depth than near the surface. In this study, we investigate the evolution of
faulting, topography, and stress state in volcanic rift zones using a kinematic model for
dike injection in an extending 2-D elastic-viscoplastic layer. We show that the intrusion
of blade-like dikes focuses deformation at the rift axis, leading to the formation of an
axial rift valley. However, flexure associated with the development of the rift topography
generates compression at the base of the plate. If the magnitude of these deviatoric
compressive stresses exceeds the deviatoric tensile stress associated with far-field
extension, further dike injection will be inhibited. In general, this transition from tensile
to compressive deviatoric stresses occurs when the rate of accretion in the lower crust is
greater than 50-60% of the far-field extension rate. These results indicate that over
geologic time-scales the injection of blade-like dikes is a self-limiting process in which
dike-generated faulting and topography result in an efficient feedback mechanism that
controls the time-averaged distribution of magma accretion within the crust.Funding
for this research was provided by NSF Grants OCE 04-43246, OCE 05-50147, OCE 02-42597 and OCE 04-26575, and a Carnegie Postdoctoral Fellowship to M.B
Information and Particle Physics
Information measures for relativistic quantum spinors are constructed to
satisfy various postulated properties such as normalisation invariance and
positivity. Those measures are then used to motivate generalised Lagrangians
meant to probe shorter distance physics within the maximum uncertainty
framework. The modified evolution equations that follow are necessarily
nonlinear and simultaneously violate Lorentz invariance, supporting previous
heuristic arguments linking quantum nonlinearity with Lorentz violation. The
nonlinear equations also break discrete symmetries. We discuss the implications
of our results for physics in the neutrino sector and cosmology
Clarification of the relationship between bound and scattering states in quantum mechanics: Application to 12C + alpha
Using phase-equivalent supersymmetric partner potentials, a general result
from the inverse problem in quantum scattering theory is illustrated, i.e.,
that bound-state properties cannot be extracted from the phase shifts of a
single partial wave, as a matter of principle. In particular, recent R-matrix
analyses of the 12C + alpha system, extracting the asymptotic normalization
constant of the 2+ subthreshold state, C12, from the l=2 elastic-scattering
phase shifts and bound-state energy, are shown to be unreliable. In contrast,
this important constant in nuclear astrophysics can be deduced from the
simultaneous analysis of the l=0, 2, 4, 6 partial waves in a simplified
potential model. A new supersymmetric inversion potential and existing models
give C12=144500+-8500 fm-1/2.Comment: Expanded version (50% larger); three errors corrected (conversion of
published reduced widths to ANCs); nine references added, one remove
Epidemiology of Lead Poisoning in Cattle
The case histories of lead poisoning diagnosed in 63 herds of cattle over the past five years were studied. The toxicosis was found to be most prominent during the spring months and resulted in a 61 percent fatality rate. The clinical signs observed involved mainly the central nervous and gastrointestinal systems, as did the post mortem findings. The mean tissue lead levels were determined and correlated with the source of the toxicant
Folding model analysis of alpha radioactivity
Radioactive decay of nuclei via emission of particles has been
studied theoretically in the framework of a superasymmetric fission model using
the double folding (DF) procedure for obtaining the -nucleus
interaction potential. The DF nuclear potential has been obtained by folding in
the density distribution functions of the nucleus and the daughter
nucleus with a realistic effective interaction. The M3Y effective interaction
has been used for calculating the nuclear interaction potential which has been
supplemented by a zero-range pseudo-potential for exchange along with the
density dependence. The nuclear microscopic -nucleus potential thus
obtained has been used along with the Coulomb interaction potential to
calculate the action integral within the WKB approximation. This subsequently
yields microscopic calculations for the half lives of decays of
nuclei. The density dependence and the exchange effects have not been found to
be very significant. These calculations provide reasonable estimates for the
lifetimes of radioactivity of nuclei.Comment: 7 pages including 1 figur
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