1,978 research outputs found
A general resonance theory based on Mourre's inequality
We study the perturbation of bound states embedded in the continuous spectrum
which are unstable by the Fermi Golden Rule. The approach to resonance theory
based on spectral deformation is extended to a more general class of quantum
systems characterized by Mourre's inequality and smoothness of the resolvent.
Within the framework of perturbation theory it is still possible to give a
definite meaning to the notion of complex resonance energies and of
corresponding metastable states. The main result is a quasi-exponential decay
estimate up to a controlled error of higher order in perturbation theory.Comment: 17 page
Archaeological Testing at Goliad State Park, Goliad County, Texas
In December 1996, the Center for Archaeological Research (CAR) of The University of Texas at San Antonio entered into a contract with the Texas Parks and Wildlife Department to conduct archaeological investigations at Mission Espiritu Santo in Goliad State Park. On December 17, 1996, a seven-member field crew from CAR excavated 32 shovel tests along the proposed trench for replacement of existing park water and electrical lines between the mission compound and the camping area. Artifacts recovered from the shovel tests include Spanish colonial ceramics, glass, metal, stone tools and debitage, and a large quantity of animal bone. Most of the artifacts were recovered from the shovel test pits near the mission wall. Any new trenching in this area would disturb possible intact Colonial deposits. Very few artifacts were recovered from the remainder of the proposed trench line
Canonical Expansion of PT-Symmetric Operators and Perturbation Theory
Let be any \PT symmetric Schr\"odinger operator of the type on , where is
any odd homogeneous polynomial and . It is proved that is
self-adjoint and that its eigenvalues coincide (up to a sign) with the singular
values of , i.e. the eigenvalues of . Moreover we
explicitly construct the canonical expansion of and determine the singular
values of through the Borel summability of their divergent
perturbation theory. The singular values yield estimates of the location of the
eigenvalues \l_j of by Weyl's inequalities.Comment: 20 page
Limiting absorption principle and perfectly matched layer method for Dirichlet Laplacians in quasi-cylindrical domains
We establish a limiting absorption principle for Dirichlet Laplacians in
quasi-cylindrical domains. Outside a bounded set these domains can be
transformed onto a semi-cylinder by suitable diffeomorphisms. Dirichlet
Laplacians model quantum or acoustically-soft waveguides associated with
quasi-cylindrical domains. We construct a uniquely solvable problem with
perfectly matched layers of finite length. We prove that solutions of the
latter problem approximate outgoing or incoming solutions with an error that
exponentially tends to zero as the length of layers tends to infinity. Outgoing
and incoming solutions are characterized by means of the limiting absorption
principle.Comment: to appear in SIAM Journal on Mathematical Analysi
Free Fermionic Heterotic Model Building and Root Systems
We consider an alternative derivation of the GSO Projection in the free
fermionic construction of the weakly coupled heterotic string in terms of root
systems, as well as the interpretation of the GSO Projection in this picture.
We then present an algorithm to systematically and efficiently generate input
sets (i.e. basis vectors) in order to study Landscape statistics with minimal
computational cost. For example, the improvement at order 6 is approximately
10^{-13} over a traditional brute force approach, and improvement increases
with order. We then consider an example of statistics on a relatively simple
class of models.Comment: Standard Latex, 12 page
Heat kernel estimates and spectral properties of a pseudorelativistic operator with magnetic field
Based on the Mehler heat kernel of the Schroedinger operator for a free
electron in a constant magnetic field an estimate for the kernel of E_A is
derived, where E_A represents the kinetic energy of a Dirac electron within the
pseudorelativistic no-pair Brown-Ravenhall model. This estimate is used to
provide the bottom of the essential spectrum for the two-particle
Brown-Ravenhall operator, describing the motion of the electrons in a central
Coulomb field and a constant magnetic field, if the central charge is
restricted to Z below or equal 86
Extrakorporale Stoßwellentherapie eines komplizierten chronischen Ulcus cruris venosum
Zusammenfassung: Extrakorporale Stoßwellen werden definiert als eine Sequenz von akustischen Schallimpulsen, die einen charakteristisch schnellen Druckanstieg auf über 100MPa mit Abfall auf Normaldruck in wenigen Mikrosekunden aufweisen. In den 1980er-Jahren wurde die extrakorporale Stoßwellenlithotripsie (ESWL) erstmals zur Behandlung der Urolithiasis angewandt. Orthopäden setzten anschließend die extrakorporale Stoßwellentherapie (ESWT) zur Behandlung von nicht heilenden Frakturen, Tendinopathien und Osteonekrose ein. Die erste Anwendung von ESWT in der Dermatologie erfolgte zur Behandlung des chronischen Ulcus cruris. Verschiedene Studien der letzten 10Jahre zeigten, dass die ESWT die Angiogenese stimuliert und die Perfusion im ischämischen Gewebe verbessert, die Entzündungsreaktion mindert, die Zelldifferenzierung unterstützt und hiermit die Wundheilung deutlich verbessern kann. Wir setzten die ESWT erfolgreich zur Behandlung eines komplizierten chronischen venösen Ulcus cruris ein. Weiter konnten wir eine Verbesserung des lymphatischen Abflusses nach Applikation von ESWT beobachten. Die ESWT stellt somit eine nebenwirkungsarme und effiziente physikalische Therapiemodalität zur Behandlung von therapieresistenten chronischen Wunden da
Fire-cracked Rock Use and Reuse in the Hueco Bolson, Fort Bliss, Texas
The Center for Archaeological Research of The University of Texas at San Antonio conducted an analysis of 29,058 pieces of fire-cracked rock and burned caliche selected from a sample of hundreds of features tested as part of the Hueco Mountain Archaeological Project at Fort Bliss, Texas. Feature and non-feature material included in this analysis were collected from site FB 13237 located on the proximal fan, FB 12719 within the basin area, and FB 12412 situated in the transitional zone between the two.
The goal of the analysis was to identify patterns of attribute variability in burned rock that could be used to infer function of the various features and sites in the sample. Specific burned rock attributes used in the study were material type, size, weight, and the presence or absence of fracturing, cortex, and discoloration. These attributes were recorded and compared in various combinations at course- and fme-grained levels of intensity to address issues of reuse, recycling, feature function, thermally induced morphological variability, and how these variables might relate to specific land forms through time.
Through these comparisons, patterns relating to expedient material selection, feature type, reuse and feature function were identified
Der internistische Check-up
Zusammenfassung: Viele präventive Maßnahmen bei gesunden Erwachsenen werden in zunehmendem Maße durch Evidenz gestützt oder verworfen. Dabei sind v.a. die Beratung bezüglich Tabakabstinenz, indizierte Impfungen und das Screening in Bezug auf Übergewicht, hohen Blutdruck, Hyperlipidämie, Zervixkarzinom, kolorektales Karzinom und Mammakarzinom bewiesenermaßen wichtig und sinnvoll. Nicht empfohlen wird ein Screening für Bronchial-, Pankreas- und Ovarialkarzinom. Ein Screening für Diabetes mellitus beim jüngeren Erwachsenen, Schilddrüsenerkrankungen und Prostatakarzinom wird nicht routinemäßig empfohlen, sollte aber je nach persönlichem Risikoprofil im Sinne eines sog. "Case findings" erwogen werden. Aus ärztlicher Sicht ist es auch wichtig, auf mögliche nicht deklarierte Beweggründe für eine Check-up-Untersuchung einzugehen, um so mögliche "Hidden Agendas" der Konsultationen aufzudecke
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