2,041 research outputs found
Launch window analysis of satellites in high eccentricity or large circular orbits
Numerical methods and computer programs for studying the stability and evolution of orbits of large eccentricity are presented. Methods for determining launch windows and target dates are developed. Mathematical models are prepared to analyze the characteristics of specific missions
The roughness of stylolites: Implications of 3D high resolution topography measurements
Stylolites are natural pressure-dissolution surfaces in sedimentary rocks. We
present 3D high resolution measurements at laboratory scales of their complex
roughness. The topography is shown to be described by a self-affine scaling
invariance. At large scales, the Hurst exponent is and
very different from that at small scales where . A
cross-over length scale at around \L_c =1~mm is well characterized.
Measurements are consistent with a Langevin equation that describes the growth
of a stylolitic interface as a competition between stabilizing long range
elastic interactions at large scales or local surface tension effects at small
scales and a destabilizing quenched material disorder.Comment: 4 pages, 4 figure
Logarithmic SUSY electroweak effects on four-fermion processes at TeV energies
We compute the MSSM one-loop contributions to the asymptotic energy behaviour
of fermion-antifermion pair production at future lepton-antilepton colliders.
Besides the conventional logarithms of Renormalization Group origin, extra SUSY
linear logarithmic terms appear of "Sudakov-type". In the TeV range their
overall effect on a variety of observables can be quite relevant and
drastically different from that obtained in the SM case.Comment: 19 pages and 14 figures, corrected version. e-mail:
[email protected]
Equal Time Correlations in Haldane Gap Antiferromagnets
The antiferromagnetic Heisenberg chain both with and without single ion
anisotropy is studied. Using the recently proposed density matrix
renormalization group technique we calculate the energy gaps as well as several
different correlation functions. The two gaps, ,
along with associated correlation lengths and velocities are determined. The
numerical results are shown to be in good agreement with theoretical
predictions derived from the nonlinear sigma model and a free boson model. We
also study the excitations that occur at the ends of open chains; in
particular we study the behavior associated with open boundary conditions,
using a model of spins coupled to the free bosons.Comment: 32 pages, uufiles encoded REVTEX 3.0, 19 postscript figures included,
UBCTP-93-02
MĂ©dicaments chez les seniors vaudois Ă domicile : nombre et composition
La question de la pertinence et de la sécurité des traitements médicamenteux dans la population ùgée prend toujours plus d'importance dans nos sociétés en raison de l'accroissement en nombre des personnes ùgées et de l'expansion continuelle des possibilités thérapeutiques. La nécessité d'individualiser et de rationnaliser la prescription chez le sujet ùgé est universellement reconnue. Par ailleurs, il est bien documenté que le fait de prendre un nombre élevé de médicaments différents accroßt le risque d'effets indésirables, de défaut d'adhérence et de difficultés de gestion des traitements. La présente étude explore les traitements médicamenteux des seniors vaudois et formule des propositions visant une «polymédication rationnelle».
Une enquĂȘte conduite en 2012 dans le canton de Vaud auprĂšs de 3'133 personnes ĂągĂ©es de 69 ans et plus vivant en domicile privĂ© comportait une section sur le traitement mĂ©dicamenteux actuel des rĂ©pondants (autodĂ©claration, questionnaire rempli Ă domicile). Les rĂ©ponses Ă cette question sont analysĂ©es dans l'objectif de dĂ©crire la consommation de mĂ©dicaments en termes quantitatifs (notamment mesurer la prĂ©valence de la polymĂ©dication), ainsi que la relation entre polymĂ©dication et certains facteurs d'influence, et la composition des traitements
Excitation Spectrum of Antiferromagnetic Chains
The dynamical structure factor of the antiferromagnetic
Heisenberg chain with length 20 at zero temperature is calculated. The lowest
energy states have the delta-function peak at the region . At the lowest energy states are the lower-edge
of the continuum of the scattering state, the strength of which decreases for
large systems. This gives a reasonable explanation for the experimental fact
that no clear peak is observed at the region . This situation is more
apparent for valence-bond solid state. On the contrary for
antiferromagnetic Heisenberg chain the lowest energy states are always the edge
of the continuum.Comment: 14pages, Revtex 3.0, No.279
Hyperon-Nucleon Final State Interaction in Kaon Photoproduction of the Deuteron
Final state hyperon-nucleon interaction in strangeness photoproduction of the
deuteron is investigated making use of the covariant reaction formalism and the
P-matrix approach to the YN system. Remarkably simple analytical expression for
the amplitude is obtained. Pronounced effects due to final state interaction
are predicted including the manifestation of the 2.13 GeV resonance.Comment: LaTeX, 13 page
Hadron Production via e+e- Collisions with Initial State Radiation
A novel method of studying e+e- annihilation into hadrons using initial state
radiation at e+e- colliders is described. After brief history of the method,
its theoretical foundations are considered. Numerous experiments in which
exclusive cross sections of e+e- annihilation into hadrons below the
center-of-mass energy of 5 GeV have been measured are presented. Some
applications of the results obtained to fundamental tests of the Standard Model
are listed.Comment: 50 pages, 88 figures, accepted for publication in Rev. Mod. Phy
S(k) for Haldane Gap Antiferromagnets: Large-scale Numerical Results vs. Field Theory and Experiment
The structure function, S(k), for the s=1, Haldane gap antiferromagnetic
chain, is measured accurately using the recent density matrix renormalization
group method, with chain-length 100. Excellent agreement with the nonlinear
model prediction is obtained, both at where a single
magnon process dominates and at where a two magnon process
dominates. We repeat our calculation with crystal field anisotropy chosen to
model NENP, obtaining good agreement with both field theory predictions and
recent experiments. Correlation lengths, gaps and velocities are determined for
both polarizations.Comment: 11 pages, 3 postscript figures included, REVTEX 3.0, UBCTP-93-02
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