11,365 research outputs found
Development of \u3ci\u3eOrius Insidiosus\u3c/i\u3e (Hemiptera: Anthocoridae) in Relation to Temperature
A developmental threshold of lO.3°C and a thermal constant of 307 day-degrees C were estimated for a Wisconsin population of Orius insidiosus (Say) (Hemiptera: Anthocoridae) by rearing eggs and nymphs at various constant temperatures
Variations and trends in state nursing facility capacity: 1978-93.
The demand for nursing facility (NF) beds has been growing with the aging of the population and many other factors. As the need for nursing home care grows, the Nation's capacity to provide such care is the subject of increasing concern. This article examines licensed NFs and beds, presenting data on trends from 1978-93. Measures of the adequacy of NF beds in States are examined over time, including the ratio of beds per aged population, occupancy rates, and State official's opinions of the adequacy of supply. State and regional variations are shown over time, and we speculate on the factors which may be associated with the variation
Triple-Pomeron Matrix Model for Dispersive Corrections to Nucleon-Nucleus Total Cross Section
Dispersive corrections to the total cross section for high-energy scattering
from a heavy nucleus are calculated using a matrix model, based on the
triple-Pomeron behavior of diffractive scattering from a single nucleon, for
the cross section operator connecting different states of the projectile
nucleon . Energy-dependent effects due to the decrease in longitudinal momentum
transfers and the opening of more channels with increasing energy are included.
The three leading terms in an expansion in the number of inelastic transitions
are evaluated and compared to exact results for the model in the uniform
nuclear density approximation for the the scattering of nucleons from Pb^{208}
for laboratory momenta ranging from 50 to 200 GeV/c.Comment: 16 pages, 2 figures, RevTex
A simple method for detection of mitochondrial DNA polymorphisms
Polymorphisms were identified in mtDNA of Heterobasidion annosum by digesting total genomic DNA with HaeIII, CfoI, or MspI, which recognize the restriction sites GGCC, GCGC, and CCGG, respectively. Most DNA was digested to fragments of less than 2 kb, while AT-rich fragments of 1.7 to 17 kb stood out as bands of uniform intensity after ethidium bromide staining. These fragments hybridized to mtDNA probes and were inherited in a uniparental fashion
Temperature dependence of instantons in QCD
We investigate the temperature dependence of the instanton contents of gluon
fields, using unquenched lattice QCD and the cooling method. The instanton size
parameter deduced from the correlation function decreases from 0.44fm below the
phase-transition temperature (MeV) to 0.33fm at 1.3 .
The instanton charge distribution is Poissonian above , but it deviates
from the convoluted Poisson at low temperature. The topological susceptibility
decreases rapidly below , showing the apparent restoration of the
symmetry already at .Comment: 8 pages TEX, 3 Postscript figures available at
http://www.krl.caltech.edu/preprints/MAP.htm
The Formation of the First Stars II. Radiative Feedback Processes and Implications for the Initial Mass Function
We consider the radiative feedback processes that operate during the
formation of the first stars, including the photodissociation of H_2, Ly-alpha
radiation pressure, formation and expansion of an HII region, and disk
photoevaporation. These processes may inhibit continued accretion once the
stellar mass has reached a critical value, and we evaluate this mass separately
for each process. Photodissociation of H_2 in the local dark matter minihalo
occurs relatively early in the growth of the protostar, but we argue this does
not affect subsequent accretion since by this time the depth of the potential
is large enough for accretion to be mediated by atomic cooling. However,
neighboring starless minihalos can be affected. Ionization creates an HII
region in the infalling envelope above and below the accretion disk. Ly-alpha
radiation pressure acting at the boundary of the HII region is effective at
reversing infall from narrow polar directions when the star reaches ~20-30Msun,
but cannot prevent infall from other directions. Expansion of the HII region
beyond the gravitational escape radius for ionized gas occurs at masses
~50-100Msun, depending on the accretion rate and angular momentum of the
inflow. However, again, accretion from the equatorial regions can continue
since the neutral accretion disk has a finite thickness and shields a
substantial fraction of the accretion envelope from direct ionizing flux. At
higher stellar masses, ~140Msun in the fiducial case, the combination of
declining accretion rates and increasing photoevaporation-driven mass loss from
the disk act to effectively halt the increase in the protostellar mass. We
identify this process as the mechanism that terminates the growth of Population
III stars... (abridged)Comment: 31 pages, including 10 figures, accepted to Ap
The interpretation of the field angle dependence of the critical current in defect-engineered superconductors
We apply the vortex path model of critical currents to a comprehensive
analysis of contemporary data on defect-engineered superconductors, showing
that it provides a consistent and detailed interpretation of the experimental
data for a diverse range of materials. We address the question of whether
electron mass anisotropy plays a role of any consequence in determining the
form of this data and conclude that it does not. By abandoning this false
interpretation of the data, we are able to make significant progress in
understanding the real origin of the observed behavior. In particular, we are
able to explain a number of common features in the data including shoulders at
intermediate angles, a uniform response over a wide angular range and the
greater discrimination between individual defect populations at higher fields.
We also correct several misconceptions including the idea that a peak in the
angular dependence of the critical current is a necessary signature of strong
correlated pinning, and conversely that the existence of such a peak implies
the existence of correlated pinning aligned to the particular direction. The
consistency of the vortex path model with the principle of maximum entropy is
introduced.Comment: 14 pages, 7 figure
Calorons in Weyl Gauge
We demonstrate by explicit construction that while the untwisted
Harrington-Shepard caloron is manifestly periodic in Euclidean time,
with period , when transformed to the Weyl () gauge,
the caloron gauge field is periodic only up to a large gauge
transformation, with winding number equal to the caloron's topological charge.
This helps clarify the tunneling interpretation of these solutions, and their
relation to Chern-Simons numbers and winding numbers.Comment: 10 pages, 10 figures, a sign typo in equation 27 is correcte
Calorons and localization of quark eigenvectors in lattice QCD
We analyze the localization properties for eigenvectors of the Dirac operator
in quenched lattice QCD in the vicinity of the deconfinement phase transition.
Studying the characteristic differences between the Z_3 sectors above the
critical temperature T_c, we find indications for the presence of calorons.Comment: 4 pages, 4 figure
Calorons, instantons and constituent monopoles in SU(3) lattice gauge theory
We analyze the zero-modes of the Dirac operator in quenched SU(3) gauge
configurations at non-zero temperature and compare periodic and anti-periodic
temporal boundary conditions for the fermions. It is demonstrated that for the
different boundary conditions often the modes are localized at different
space-time points and have different sizes. Our observations are consistent
with patterns expected for Kraan - van Baal solutions of the classical
Yang-Mills equations. These solutions consist of constituent monopoles and the
zero-modes are localized on different constituents for different boundary
conditions. Our findings indicate that the excitations of the QCD vacuum are
more structured than simple instanton-like lumps.Comment: Remarks added. To appear in Phys. Rev.
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