22,122 research outputs found
IBM: parameter symmetry, hidden symmetries and transformations of boson operators
A symmetry of the parameter space of interacting boson models IBM-1 and IBM-2
is studied. The symmetry is associated with linear canonical transformations of
boson operators, or, equivalently, with the existence of different realizations
of the symmetry algebras of the models. The relevance of the parameter symmetry
to physical observables is discussed.Comment: LATEX, 11 pages including 1 eps figure and 1 table prepared as an eps
figure; a talk given by A. M. Siirokov at XXII Symposium on Nuclear Physics,
Oaxtepec, Morelos, M\'exico, 5--8 January, 1999; to be published in Revista
Mex. Fi
Influence of Lorentz- and CPT-violating terms on the Dirac equation
The influence of Lorentz- and CPT-violating terms (in "vector" and "axial
vector" couplings) on the Dirac equation is explicitly analyzed: plane wave
solutions, dispersion relations and eigenenergies are explicitly obtained. The
non-relativistic limit is worked out and the Lorentz-violating Hamiltonian
identified in both cases, in full agreement with the results already
established in the literature. Finally, the physical implications of this
Hamiltonian on the spectrum of hydrogen are evaluated both in the absence and
presence of a magnetic external field. It is observed that the fixed
background, when considered in a vector coupling, yields no qualitative
modification in the hydrogen spectrum, whereas it does provide an effective
Zeeman-like splitting of the spectral lines whenever coupled in the axial
vector form. It is also argued that the presence of an external fixed field
does not imply new modifications on the spectrum.Comment: 13 pages, no figures, revtex4 styl
Multimedia-based Medicinal Plants Sustainability Management System
Medicinal plants are increasingly recognized worldwide as an alternative source of efficacious and inexpensive medications to synthetic chemo-therapeutic compound. Rapid declining wild stocks of medicinal plants accompanied by adulteration and species substitutions reduce their efficacy, quality and safety. Consequently, the low accessibility to and non-affordability of orthodox medicine costs by rural dwellers to be healthy and economically productive further threaten their life expectancy. Finding comprehensive information on medicinal plants of conservation concern at a global level has been difficult. This has created a gap between computing technologiesâ promises and expectations in the healing process under complementary and alternative medicine. This paper presents the design and implementation of a Multimedia-based Medicinal Plants Sustainability Management System addressing these concerns. Medicinal plantsâ details for designing the system were collected through semi-structured interviews and databases. Unified Modelling Language, Microsoft-Visual-Studio.Net, C#3.0, Microsoft-Jet-Engine4.0, MySQL, Loquendo Multilingual Text-to-Speech Software, YouTube, and VLC Media Player were used.
Keywords: Complementary and Alternative Medicine, conservation, extinction, medicinal plant, multimedia, phytoconstituents, rural dweller
Experiences of living with chronic back pain: The physical disabilities
Purpose. Back-related functional limitations are largely assessed using lists of activities, each scored on a yes/no basis and the scores then summed. This provides little information about how chronic back pain (CBP) patients live with their condition. This study describes the consequences of living day-to-day with CBP and documents the 'insider' accounts of its impact on daily life.
Method. Unstructured interviews, using the 'Framework' approach with topic guide, were recorded and transcribed verbatim. Subjects were sampled for age, sex, ethnicity and occupation from new referrals with back pain to a rheumatology outpatient clinic. Eleven subjects (5 male, 6 female) were interviewed either in English (n = 9) or their preferred language (n = 2). Interviews were read in-depth twice to identify the topics. Data were extracted in phrases and sentences using thematic content analysis.
Results. Four themes emerged: sleep/rest, mobility, independence and leisure. All subjects reported issues about sleep and rest, nine about mobility, seven about independence and six on leisure. Most descriptions concerned loss and limitation in daily life. Strategies for coping with sleep disruption and physical limitations were described.
Conclusions. Subjects provided graphic 'in-depth' descriptions of experiences living with CBP every day; expressed regret at the loss of capabilities and distress at the functional consequences of those losses. Facilitating 'adjustment' to 'loss' may be more helpful than inferring the potential for a life free of pain as a result of therapeutic endeavours
Classical no-cloning theorem under Liouville dynamics by non-Csisz\'ar f-divergence
The Csisz\'ar f-divergence, which is a class of information distances, is
known to offer a useful tool for analysing the classical counterpart of the
cloning operations that are quantum mechanically impossible for the factorized
and marginality classical probability distributions under Liouville dynamics.
We show that a class of information distances that does not belong to this
divergence class also allows for the formulation of a classical analogue of the
quantum no-cloning theorem. We address a family of nonlinear Liouville-like
equations, and generic distances, to obtain constraints on the corresponding
functional forms, associated with the formulation of classical analogue of the
no-cloning principle.Comment: 6 pages, revised, published versio
The MHD Kelvin-Helmholtz Instability II: The Roles of Weak and Oblique Fields in Planar Flows
We have carried out high resolution MHD simulations of the nonlinear
evolution of Kelvin-Helmholtz unstable flows in 2 1/2 dimensions. The modeled
flows and fields were initially uniform except for a thin shear layer with a
hyperbolic tangent velocity profile and a small, normal mode perturbation. The
calculations consider periodic sections of flows containing magnetic fields
parallel to the shear layer, but projecting over a full range of angles with
respect to the flow vectors. They are intended as preparation for fully 3D
calculations and to address two specific questions raised in earlier work: 1)
What role, if any, does the orientation of the field play in nonlinear
evolution of the MHD Kelvin-Helmholtz instability in 2 1/2 D. 2) Given that the
field is too weak to stabilize against a linear perturbation of the flow, how
does the nonlinear evolution of the instability depend on strength of the
field. The magnetic field component in the third direction contributes only
through minor pressure contributions, so the flows are essentially 2D. Even a
very weak field can significantly enhance the rate of energy dissipation. In
all of the cases we studied magnetic field amplification by stretching in the
vortex is limited by tearing mode, ``fast'' reconnection events that isolate
and then destroy magnetic flux islands within the vortex and relax the fields
outside the vortex. If the magnetic tension developed prior to reconnection is
comparable to Reynolds stresses in the flow, that flow is reorganized during
reconnection. Otherwise, the primary influence on the plasma is generation of
entropy. The effective expulsion of flux from the vortex is very similar to
that shown by Weiss for passive fields in idealized vortices with large
magnetic Reynolds numbers. We demonstrated that thisComment: 23 pages of ApJ Latex (aaspp4.sty) with 10 figures, high resolution
postscript images for figs 4-9 available through anonymous at
ftp://ftp.msi.umn.edu/pub/twj To appear in the June 10, 1997 Ap
On the number of eigenvalues of Schrödinger operators with complex potentials
We study the eigenvalues of Schrödinger operators with complex potentials in odd space dimensions. We obtain bounds on the total number of eigenvalues in the case where VV decays exponentially at infinity
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