54,248 research outputs found
Quantum theory of large amplitude collective motion and the Born-Oppenheimer method
We study the quantum foundations of a theory of large amplitude collective
motion for a Hamiltonian expressed in terms of canonical variables. In previous
work the separation into slow and fast (collective and non-collective)
variables was carried out without the explicit intervention of the Born
Oppenheimer approach. The addition of the Born Oppenheimer assumption not only
provides support for the results found previously in leading approximation, but
also facilitates an extension of the theory to include an approximate
description of the fast variables and their interaction with the slow ones.
Among other corrections, one encounters the Berry vector and scalar potential.
The formalism is illustrated with the aid of some simple examples, where the
potentials in question are actually evaluated and where the accuracy of the
Born Oppenheimer approximation is tested. Variational formulations of both
Hamiltonian and Lagrangian type are described for the equations of motion for
the slow variables.Comment: 29 pages, 1 postscript figure, preprint no UPR-0085NT. Latex + epsf
styl
Stability of the proton-to-electron mass ratio
We report a limit on the fractional temporal variation of the
proton-to-electron mass ratio as, obtained by comparing the frequency of a
rovibrational transition in SF6 with the fundamental hyperfine transition in
Cs. The SF6 transition was accessed using a CO2 laser to interrogate spatial
2-photon Ramsey fringes. The atomic transition was accessed using a primary
standard controlled with a Cs fountain. This result is direct and model-free
An assessment and validation study of nuclear reactors for low power space applications
The feasibility and safety of six conceptual small, low power nuclear reactor designs was evaluated. Feasibility evaluations included the determination of sufficient reactivity margins for seven years of full power operation and safe shutdown as well as handling during pre-launch assembly phases. Safety evaluations were concerned with the potential for maintaining subcritical conditions in the event of launch or transportation accidents. These included water immersion accident scenarios both with and without water flooding the core. Results show that most of the concepts can potentially meet the feasibility and safety requirements; however, due to the preliminary nature of the designs considered, more detailed designs will be necessary to enable these concepts to fully meet the safety requirements
Seven-fluorochrome mouse M-FISH for high-resolution analysis of interchromosomal rearrangements
The mouse has evolved to be the primary mammalian genetic model organism. Important applications include the modeling of human cancer and cloning experiments. In both settings, a detailed analysis of the mouse genome is essential. Multicolor karyotyping technologies have emerged to be invaluable tools for the identification of mouse chromosomes and for the deciphering of complex rearrangements. With the increasing use of these multicolor technologies resolution limits are critical. However, the traditionally used probe sets, which employ 5 different fluorochromes, have significant limitations. Here, we introduce an improved labeling strategy. Using 7 fluorochromes we increased the sensitivity for the detection of small interchromosomal rearrangements (700 kb or less) to virtually 100%. Our approach should be important to unravel small interchromosomal rearrangements in mouse models for DNA repair defects and chromosomal instability. Copyright (C) 2003 S. Karger AG, Basel
On the Nature of “Good” Goods and the Ethical Role of Marketing
The purpose of this essay is to elaborate on an important section of a document titled, Vocation of the Business Leader, published by the Pontifical Council for Justice and Peace. Subtitled “A Reflection,” this document is an 87 paragraph, 13,000 word (in English) statement about the ideals of business leadership as inspired by Christian values and ethics. It was sponsored by Peter K.A. Cardinal Turkson and Bishop Mario Toso in consultation with assorted educators, theologians, economists, and philosophers. The document developed from reflections and discussions on Pope Benedict XVI’s social encyclical Caritas in Veritate, particularly a seminar organized by the Pontifical Council for Justice and Peace in February 2011. As such, it extends Caritas in Veritate, especially with regard to economics and business
Religion-motivated Enterprises in the Marketplace: A Macromarketing Inquiry
This exploratory essay identifies and examines a variety of religiously affiliated or inspired enterprises operating in otherwise secular marketplaces. While explicitly recognizing that some marketplace manifestations of religion can be controversial, even dysfunctional, it argues for the evident macromarketing relevance of this project. The approach for analyzing what this paper refers to as “religion-motivated enterprises” (RMEs) consists of (1) a nominal classification scheme to illustrate and categorize the diversity of RME examples; (2) some foundational principles shared among major faith traditions that provide a basis for an RME ethos; and (3) basic propositions that, with future empirical testing, may explain the contributions of these organizations to improved market performance. Our commentary includes environmental factors that prompted the establishment of many RMEs, the nature of their sustainability, and the importance of mission statements to their operations. Finally, we identify opportunities for additional research and summarize the macromarketing contributions of this article
A new model for deflagration fronts in reactive fluids
We present a new way of modeling deflagration fronts in reactive fluids, the
main emphasis being on turbulent thermonuclear deflagration fronts in white
dwarfs undergoing a Type Ia supernova explosion. Our approach is based on a
level set method which treats the front as a mathematical discontinuity and
allows full coupling between the front geometry and the flow field. With only
minor modifications, this method can also be applied to describe contact
discontinuities. Two different implementations are described and their
physically correct behaviour for simple testcases is shown. First results of
the method applied to the concrete problems of Type Ia supernovae and chemical
hydrogen combustion are briefly discussed; a more extensive analysis of our
astrophysical simulations is given in (Reinecke et al. 1998, MPA Green Report
1122b).Comment: 11 pages, 13 figures, accepted by A&A, corrected and extended
according to referee's comment
Exact relativistic treatment of stationary counter-rotating dust disks III. Physical Properties
This is the third in a series of papers on the construction of explicit
solutions to the stationary axisymmetric Einstein equations which can be
interpreted as counter-rotating disks of dust. We discuss the physical
properties of a class of solutions to the Einstein equations for disks with
constant angular velocity and constant relative density which was constructed
in the first part. The metric for these spacetimes is given in terms of theta
functions on a Riemann surface of genus 2. It is parameterized by two physical
parameters, the central redshift and the relative density of the two
counter-rotating streams in the disk. We discuss the dependence of the metric
on these parameters using a combination of analytical and numerical methods.
Interesting limiting cases are the Maclaurin disk in the Newtonian limit, the
static limit which gives a solution of the Morgan and Morgan class and the
limit of a disk without counter-rotation. We study the mass and the angular
momentum of the spacetime. At the disk we discuss the energy-momentum tensor,
i.e. the angular velocities of the dust streams and the energy density of the
disk. The solutions have ergospheres in strongly relativistic situations. The
ultrarelativistic limit of the solution in which the central redshift diverges
is discussed in detail: In the case of two counter-rotating dust components in
the disk, the solutions describe a disk with diverging central density but
finite mass. In the case of a disk made up of one component, the exterior of
the disks can be interpreted as the extreme Kerr solution.Comment: 30 pages, 20 figures; to appear in Phys. Rev.
Foundations of self-consistent particle-rotor models and of self-consistent cranking models
The Kerman-Klein formulation of the equations of motion for a nuclear shell
model and its associated variational principle are reviewed briefly. It is then
applied to the derivation of the self-consistent particle-rotor model and of
the self-consistent cranking model, for both axially symmetric and triaxial
nuclei. Two derivations of the particle-rotor model are given. One of these is
of a form that lends itself to an expansion of the result in powers of the
ratio of single-particle angular momentum to collective angular momentum, that
is essentual to reach the cranking limit. The derivation also requires a
distinct, angular-momentum violating, step. The structure of the result implies
the possibility of tilted-axis cranking for the axial case and full
three-dimensional cranking for the triaxial one. The final equations remain
number conserving. In an appendix, the Kerman-Klein method is developed in more
detail, and the outlines of several algorithms for obtaining solutions of the
associated non-linear formalism are suggested.Comment: 29 page
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