82,820 research outputs found
Nucleon-nucleon potentials in phase-space representation
A phase-space representation of nuclear interactions, which depends on the
distance and relative momentum of the nucleons, is
presented. A method is developed that permits to extract the interaction
from antisymmetrized matrix elements given in a spherical
basis with angular momentum quantum numbers, either in momentum or coordinate
space representation. This representation visualizes in an intuitive way the
non-local behavior introduced by cutoffs in momentum space or renormalization
procedures that are used to adapt the interaction to low momentum many-body
Hilbert spaces, as done in the unitary correlation operator method or with the
similarity renormalization group. It allows to develop intuition about the
various interactions and illustrates how the softened interactions reduce the
short-range repulsion in favor of non-locality or momentum dependence while
keeping the scattering phase shifts invariant. It also reveals that these
effective interactions can have undesired complicated momentum dependencies at
momenta around and above the Fermi momentum. Properties, similarities and
differences of the phase-space representations of the Argonne and the N3LO
chiral potential, and their UCOM and SRG derivatives are discussed
Robotic observations of the most eccentric spectroscopic binary in the sky
The visual A component of the Gliese 586AB system is a double-lined
spectroscopic binary consisting of two cool stars with the exceptional orbital
eccentricity of 0.976. Such an extremely eccentric system may be important for
our understanding of low-mass binary formation. We present a total of 598
high-resolution echelle spectra from our robotic facility STELLA from 2006-2012
which we used to compute orbital elements of unprecedented accuracy. The orbit
constrains the eccentricity to 0.97608+/-0.00004 and the orbital period to
889.8195+/-0.0003d. The masses of the two components are 0.87+/-0.05 Msun and
0.58+/-0.03 Msun if the inclination is 5+/-1.5degr as determined from
adaptive-optics images, that is good to only 6% due to the error of the
inclination although the minimum masses reached a precision of 0.3%. The flux
ratio Aa:Ab in the optical is betwee n 30:1 in Johnson-B and 11:1 in I. Radial
velocities of the visual B-component (K0-1V) appear constant to within 130 m/s
over six years. Sinusoidal modulations of Teff of Aa with an amplitude of apprx
55 K are seen with the orbital period. Component Aa appears warmest at
periastron and coolest at apastron, indicating atmospheric changes induced by
the high orbital eccentricity. No light variations larger than approximately 4
mmag are detected for A, while a photometric period of 8.5+/-0.2 d with an
amplitude of 7 mmag is discovered for the active star B, which we interpret to
be its rotation period. We estimate an orbital period of approx 50,000 yr for
the AB system. The most likely age of the AB system is >=2 Gyr, while the
activity of the B component, if it were a single star, would imply 0.5 Gyr.
Both Aa and B are matched with single-star evolutionary tracks of their
respective mass
From nucleon-nucleon interaction matrix elements in momentum space to an operator representation
Starting from the matrix elements of the nucleon-nucleon interaction in
momentum space we present a method to derive an operator representation with a
minimal set of operators that is required to provide an optimal description of
the partial waves with low angular momentum. As a first application we use this
method to obtain an operator representation for the Argonne potential
transformed by means of the unitary correlation operator method and discuss the
necessity of including momentum dependent operators. The resulting operator
representation leads to the same results as the original momentum space matrix
elements when applied to the two-nucleon system and various light nuclei. For
applications in fermionic and antisymmetrized molecular dynamics, where an
operator representation of a soft but realistic effective interaction is
indispensable, a simplified version using a reduced set of operators is given
A program to evaluate dye lasers as high power, pulsed, visible light sources
Spectral emission of visible from Q switched dye laser
Cathodoluminescence of enstatite from chondritic and achondritic meteorites and its selenological implications Technical report, 1 Sep. 1967 - 1 Jul. 1968
Cathodoluminescence of enstatite from chondritic and achondritic meteorites and selenological implication
The Effects of Market Survey Rates, Job Evaluation and Job Gender on Job Pay
The present study investigates the effects of current pay, market surveys, job evaluation points, job gender, and rater sex on pay rates for jobs. 406 compensation administrators assigned new pay rates to nine jobs in one of two matched job sets: either all predominantly female, or all predominantly male. The two sets were matched on all quantitative data (current rate, market rate, and job evaluation points), but varied in terms of job titles and descriptions. Multiple analyses of variance and regression analyses were performed to determine whether job gender had a significant effect on assigned pay rates, holding other factors constant. Regardless of the analysis employed, no evidence of gender bias was found. Limitations and suggestions for future research are offered
Some monetary facts
This article describes three long-run monetary facts derived by examining data for 110 countries over a 30-year period, using three definitions of a country's money supply and two subsamples of countries: (1) Growth rates of the money supply and the general price level are highly correlated for all three money definitions, for the full sample of countries, and for both subsamples. (2) The growth rates of money and real output are not correlated, except for a subsample of countries in the Organisation for Economic Co-operation and Development, where these growth rates are positively correlated. (3) The rate of inflation and the growth rate of real output are essentially uncorrelated. ; Reprinted in Quarterly Review, Fall 2001 (v. 25, no. 4)Money supply ; Monetary theory
Correlations in hot and dense quark matter
We present a relativistic three-body equation to investigate three-quark
clusters in hot and dense quark matter. To derive such an equation we use the
Dyson equation approach. The equation systematically includes the Pauli
blocking factors as well as the self energy corrections of quarks. Special
relativity is realized through the light front form. Presently we use a
zero-range force and investigate the Mott transition.Comment: 6 pages, 4 figure, Few-Body Systems style file
Spatial control of irreversible protein aggregation
Liquid cellular compartments spatially segregate from the cytoplasm and can
regulate aberrant protein aggregation, a process linked to several medical
conditions, including Alzheimer's and Parkinson's diseases. Yet the mechanisms
by which these droplet-like compartments affect protein aggregation remain
unknown. Here, we combine kinetic theory of protein aggregation and
liquid-liquid phase separation to study the spatial control of irreversible
protein aggregation in the presence of liquid compartments. We find that, even
for weak interactions between the compartment constituents and the aggregating
monomers, aggregates are strongly enriched inside the liquid compartment
relative to the surrounding cytoplasm. We show that this enrichment is caused
by a positive feedback mechanism of aggregate nucleation and growth which is
mediated by a flux maintaining the phase equilibrium between the compartment
and the cytoplasm. Our model predicts that the compartment volume that
maximizes aggregate enrichment in the compartment is determined by the reaction
orders of aggregate nucleation. The underlying mechanism of aggregate
enrichment could be used to confine cytotoxic protein aggregates inside
droplet-like compartments suggesting potential new avenues against aberrant
protein aggregation. Our findings could also represent a common mechanism for
the spatial control of irreversible chemical reactions in general
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