46 research outputs found
Spherical Hartree-Fock calculations with linear momentum projection before the variation.Part I: Energies, form factors, charge densities and mathematical sum rules
Spherical Hartree--Fock calculations with projection onto zero total linear
momentum before the variation are performed for the nuclei 4He, 12C, 16O, 28Si,
32S and 40Ca using a density--independent effective nucleon--nucleon
interaction. The results are compared to those of usual spherical Hartree--Fock
calculations subtracting the kinetic energy of the center of mass motion either
before or after the variation and to the results obtained analytically with
oscillator occupations. Total energies, hole--energies, elastic charge form
factors and charge densities and the mathematical Coulomb sum rules are
discussed.Comment: 16 pages, 13 postscript figure
Nilpotent Symmetries For A Spinning Relativistic Particle In Augmented Superfield Formalism
The local, covariant, continuous, anticommuting and nilpotent
Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST symmetry transformations for all
the fields of a (0 + 1)-dimensional spinning relativistic particle are obtained
in the framework of augmented superfield approach to BRST formalism. The
trajectory of this super-particle is parametrized by a monotonically increasing
parameter \tau that is embedded in a D-dimensional flat Minkowski spacetime
manifold. This physically useful one-dimensional system is considered on a
three (1 + 2)-dimensional supermanifold which is parametrized by an even
element \tau and a couple of odd elements \theta and \bar\theta of the
Grassmann algebra. Two anticommuting sets of (anti-)BRST symmetry
transformations, corresponding to the underlying (super)gauge symmetries for
the above system, are derived in the framework of augmented superfield
formulation where (i) the horizontality condition, and (ii) the invariance of
conserved quantities on the supermanifold, play decisive roles. Geometrical
interpretations for the above nilpotent symmetries (and their generators) are
provided.Comment: LaTeX file, 21 pages, a notation clarified, a footnote added and
related statements corrected in Introduction, version to appear in EPJ
Dirty black holes: Quasinormal modes
In this paper, we investigate the asymptotic nature of the quasinormal modes
for "dirty" black holes -- generic static and spherically symmetric spacetimes
for which a central black hole is surrounded by arbitrary "matter" fields. We
demonstrate that, to the leading asymptotic order, the [imaginary] spacing
between modes is precisely equal to the surface gravity, independent of the
specifics of the black hole system.
Our analytical method is based on locating the complex poles in the first
Born approximation for the scattering amplitude. We first verify that our
formalism agrees, asymptotically, with previous studies on the Schwarzschild
black hole. The analysis is then generalized to more exotic black hole
geometries. We also extend considerations to spacetimes with two horizons and
briefly discuss the degenerate-horizon scenario.Comment: 15 pages; uses iopart.cls setstack.sty; V2: one additional reference
added, no physics changes; V3: two extra references, minor changes in
response to referee comment
Amygdala 14-3-3ζ as a Novel Modulator of Escalating Alcohol Intake in Mice
Alcoholism is a devastating brain disorder that affects millions of people worldwide. The development of alcoholism is caused by alcohol-induced maladaptive changes in neural circuits involved in emotions, motivation, and decision-making. Because of its involvement in these processes, the amygdala is thought to be a key neural structure involved in alcohol addiction. However, the molecular mechanisms that govern the development of alcoholism are incompletely understood. We have previously shown that in a limited access choice paradigm, C57BL/6J mice progressively escalate their alcohol intake and display important behavioral characteristic of alcohol addiction, in that they become insensitive to quinine-induced adulteration of alcohol. This study used the limited access choice paradigm to study gene expression changes in the amygdala during the escalation to high alcohol consumption in C57BL/6J mice. Microarray analysis revealed that changes in gene expression occurred predominantly after one week, i.e. during the initial escalation of alcohol intake. One gene that stood out from our analysis was the adapter protein 14-3-3ζ, which was up-regulated during the transition from low to high alcohol intake. Independent qPCR analysis confirmed the up-regulation of amygdala 14-3-3ζ during the escalation of alcohol intake. Subsequently, we found that local knockdown of 14-3-3ζ in the amygdala, using RNA interference, dramatically augmented alcohol intake. In addition, knockdown of amygdala 14-3-3ζ promoted the development of inflexible alcohol drinking, as apparent from insensitivity to quinine adulteration of alcohol. This study identifies amygdala 14-3-3ζ as a novel key modulator that is engaged during escalation of alcohol use
Supported Decision-Making: A Viable Alternative to Guardianship?
The law has traditionally responded to cognitive disability by authorizing surrogate decision-makers to make decisions on behalf of disabled individuals. However, supported decision-making, an alternative paradigm for addressing cognitive disability, is rapidly gaining political support. According to its proponents, supported decision-making empowers individuals with cognitive challenges by ensuring that they are the ultimate decision-maker but are provided support from one or more others, giving them the assistance they need to make decisions for themselves. This article describes supported decision-making and its normative appeal. It then provides a descriptive account of how supported decision-making works based on the empirical literature on supported decision-making as well as that on shared decision-making, a related model used in medical contexts. The article shows how employing supported decision-making in lieu of guardianship, or integrating it into the guardianship system, has the potential to promote the self-determination of persons with intellectual and cognitive disabilities consistent with international and national legal norms. However, we find that, despite much rhetoric touting its advantages, little is known about how supported decision-making processes operate or about the outcomes of those processes. Further research is necessary to design and develop effective supported decisionmaking systems. We therefore propose a series of research questions to help inform policy choices surrounding supported decision-making