891 research outputs found
Diagonalization of multicomponent wave equations with a Born-Oppenheimer example
A general method to decouple multicomponent linear wave equations is presented. First, the Weyl calculus is used to transform operator relations into relations between c-number valued matrices. Then it is shown that the symbol representing the wave operator can be diagonalized systematically up to arbitrary order in an appropriate expansion parameter. After transforming the symbols back to operators, the original problem is reduced to solving a set of linear uncoupled scalar wave equations. The procedure is exemplified for a particle with a Born-Oppenheimer-type Hamiltonian valid through second order in h. The resulting effective scalar Hamiltonians are seen to contain an additional velocity-dependent potential. This contribution has not been reported in recent studies investigating the adiabatic motion of a neutral particle moving in an inhomogeneous magnetic field. Finally, the relation of the general method to standard quantum-mechanical perturbation theory is discussed
Semiclassical Time Evolution and Trace Formula for Relativistic Spin-1/2 Particles
We investigate the Dirac equation in the semiclassical limit \hbar --> 0. A
semiclassical propagator and a trace formula are derived and are shown to be
determined by the classical orbits of a relativistic point particle. In
addition, two phase factors enter, one of which can be calculated from the
Thomas precession of a classical spin transported along the particle orbits.
For the second factor we provide an interpretation in terms of dynamical and
geometric phases.Comment: 8 pages, no figure
Product rule for gauge invariant Weyl symbols and its application to the semiclassical description of guiding center motion
We derive a product rule for gauge invariant Weyl symbols which provides a
generalization of the well-known Moyal formula to the case of non-vanishing
electromagnetic fields. Applying our result to the guiding center problem we
expand the guiding center Hamiltonian into an asymptotic power series with
respect to both Planck's constant and an adiabaticity parameter already
present in the classical theory. This expansion is used to determine the
influence of quantum mechanical effects on guiding center motion.Comment: 24 pages, RevTeX, no figures; shortened version will be published in
J.Phys.
Boundary Conditions on Internal Three-Body Wave Functions
For a three-body system, a quantum wave function with definite
and quantum numbers may be expressed in terms of an internal wave
function which is a function of three internal coordinates. This
article provides necessary and sufficient constraints on to
ensure that the external wave function is analytic. These
constraints effectively amount to boundary conditions on and its
derivatives at the boundary of the internal space. Such conditions find
similarities in the (planar) two-body problem where the wave function (to
lowest order) has the form at the origin. We expect the boundary
conditions to prove useful for constructing singularity free three-body basis
sets for the case of nonvanishing angular momentum.Comment: 41 pages, submitted to Phys. Rev.
Semiclassical Green Function in Mixed Spaces
A explicit formula on semiclassical Green functions in mixed position and
momentum spaces is given, which is based on Maslov's multi-dimensional
semiclassical theory. The general formula includes both coordinate and momentum
representations of Green functions as two special cases of the form.Comment: 8 pages, typeset by Scientific Wor
Construction and Assembly of the Wire Planes for the MicroBooNE Time Projection Chamber
In this paper we describe how the readout planes for the MicroBooNE Time
Projection Chamber were constructed, assembled and installed. We present the
individual wire preparation using semi-automatic winding machines and the
assembly of wire carrier boards. The details of the wire installation on the
detector frame and the tensioning of the wires are given. A strict quality
assurance plan ensured the integrity of the readout planes. The different tests
performed at all stages of construction and installation provided crucial
information to achieve the successful realisation of the MicroBooNE wire
planes.Comment: 24 pages, 22 figures, accepted for publication as Technical Report in
JINS
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The Reality of Business Reengineering: Pacific Bell's Centrex Provisioning Process
Business process reengineering (BPR), a recently popularized management change strategy, promises radical improvements in the business processes of an organization. This article describes and analyzes one of Pacific Bell's successful reengineering initiatives, the Centrex reengineering project. It suggests that successful reengineering implementation does not necessarily meet the popular assumptions underlying BPR. Reengineering designs tend to be radical and assume change to be clean slate, process-based, top-down directed, and information technology enabled. By contrast, reengineering implementation tends to involve improvements that are incremental, rather than radical. The key to implementation appears to be a continual involvement of front-line employees and managers.Mathematic
Rape and respectability: ideas about sexual violence and social class
Women on low incomes are disproportionately represented among sexual violence survivors, yet feminist research on this topic has paid very little attention to social class. This article blends recent research on class, gender and sexuality with what we know about sexual violence. It is argued that there is a need to engage with classed distinctions between women in terms of contexts for and experiences of sexual violence, and to look at interactions between pejorative constructions of working-class sexualities and how complainants and defendants are perceived and treated. The classed division between the sexual and the feminine, drawn via the notion of respectability, is applied to these issues. This piece is intended to catalyse further research and debate, and raises a number of questions for future work on sexual violence and social class
Orthogonal polynomials of discrete variable and Lie algebras of complex size matrices
We give a uniform interpretation of the classical continuous Chebyshev's and
Hahn's orthogonal polynomials of discrete variable in terms of Feigin's Lie
algebra gl(N), where N is any complex number. One can similarly interpret
Chebyshev's and Hahn's q-polynomials and introduce orthogonal polynomials
corresponding to Lie superlagebras.
We also describe the real forms of gl(N), quasi-finite modules over gl(N),
and conditions for unitarity of the quasi-finite modules. Analogs of tensors
over gl(N) are also introduced.Comment: 25 pages, LaTe
Building Bridges with Boats: Preserving Community History through Intra- and Inter-Institutional Collaboration
This chapter discusses Launching through the Surf: The Dory Fleet of Pacific City, a project which documents the historical and contemporary role of dory fishers in the life of the coastal village of Pacific City, Oregon, U.S. Linfield College’s Department of Theatre and Communication Arts, its Jereld R. Nicholson Library, the Pacific City Arts Association, the Pacific City Dorymen\u27s Association, and the Linfield Center for the Northwest joined forces to engage in a collaborative college and community venture to preserve this important facet of Oregon’s history. Using ethnography as a theoretical grounding and oral history as a method, the project utilized artifacts from the dory fleet to augment interview data, and faculty/student teams created a searchable digital archive available via open access. The chapter draws on the authors’ experiences to identify a philosophy of strategic collaboration. Topics include project development and management, assessment, and the role of serendipity. In an era of value-added services where libraries need to continue to prove their worth, partnering with internal and external entities to create content is one way for academic libraries to remain relevant to agencies that do not have direct connections to higher education. This project not only developed a positive “town and gown” relationship with a regional community, it also benefited partner organizations as they sought to fulfill their missions. The project also serves as a potential model for intra- and inter-agency collaboration for all types of libraries
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