1,192 research outputs found
A vanishing theorem for operators in Fock space
We consider the bosonic Fock space over the Hilbert space of transversal
vector fields in three dimensions. This space carries a canonical
representation of the group of rotations. For a certain class of operators in
Fock space we show that rotation invariance implies the absence of terms which
either create or annihilate only a single particle. We outline an application
of this result in an operator theoretic renormalization analysis of Hamilton
operators, which occur in non-relativistic qed.Comment: 14 page
The heat kernel expansion for the electromagnetic field in a cavity
We derive the first six coefficients of the heat kernel expansion for the
electromagnetic field in a cavity by relating it to the expansion for the
Laplace operator acting on forms. As an application we verify that the
electromagnetic Casimir energy is finite.Comment: 12 page
Four dimensional observations of clouds from geosynchronous orbit using stereo display and measurement techniques on an interactive information processing system
Simultaneous Geosynchronous Operational Environmental Satellite (GOES) 1 km resolution visible image pairs can provide quantitative three dimensional measurements of clouds. These data have great potential for severe storms research and as a basic parameter measurement source for other areas of meteorology (e.g. climate). These stereo cloud height measurements are not subject to the errors and ambiguities caused by unknown cloud emissivity and temperature profiles that are associated with infrared techniques. This effort describes the display and measurement of stereo data using digital processing techniques
Uniqueness of the ground state in the Feshbach renormalization analysis
In the operator theoretic renormalization analysis introduced by Bach,
Froehlich, and Sigal we prove uniqueness of the ground state.Comment: 10 page
Ultrasonic Tracking of Migratory Fishes with an Internal Tag
First paragraph:
A small ultrasonic tag, 9 mm by 40 mm in size, has been developed by members of the fish orientation group at the University of Wisconsin. The tag emits a continuous signal at approximately 65 kc/sec. The signal is received via a directional hydrophone and a high quality communications receiver. Tracking ranges of up to 1 km have been obtained. The placement of the tag is internal: either into the stomach or into the body cavity of the fish. The tags and tracking equipment have been successfully employed in studies on the open water movements and orientation of white bass during their spawning migration
Ultrasonic Tracking of Migratory Fishes with an Internal Tag
First paragraph:
A small ultrasonic tag, 9 mm by 40 mm in size, has been developed by members of the fish orientation group at the University of Wisconsin. The tag emits a continuous signal at approximately 65 kc/sec. The signal is received via a directional hydrophone and a high quality communications receiver. Tracking ranges of up to 1 km have been obtained. The placement of the tag is internal: either into the stomach or into the body cavity of the fish. The tags and tracking equipment have been successfully employed in studies on the open water movements and orientation of white bass during their spawning migration
Kramers degeneracy theorem in nonrelativistic QED
Degeneracy of the eigenvalues of the Pauli-Fierz Hamiltonian with spin 1/2 is
proven by the Kramers degeneracy theorem. The Pauli-Fierz Hamiltonian at fixed
total momentum is also investigated.Comment: LaTex, 11 page
Warum rauchen Schizophreniepatienten?
Zusammenfassung: Patienten mit schizophrenen Störungen zeigen eine erhöhte Prävalenz der Nikotinabhängigkeit. Diese Arbeit beleuchtet die Zusammenhänge zwischen Schizophrenie und Nikotinkonsum. Es gibt deutliche Hinweise dafür, dass wesentliche Bereiche kognitiver Funktionen bei Patienten mit schizophrenen Erkrankungen durch Nikotin verbessert werden, insbesondere Daueraufmerksamkeit, gerichtete Aufmerksamkeit, Arbeitsgedächtnis, Kurzzeitgedächtnis und Wiedergabe aus dem Gedächtnis. Auch konnten in einigen Studien mittels ereigniskorrelierten Potenzialen (P50-Paradigma) und der Präpulsinhibition des akustisch ausgelösten Schreckreflexes gezeigt werden, dass präattentive Maße der Informationsverarbeitung, die eine zentrale Rolle in der Schizophrenie spielen, durch Gabe von Nikotin verbessert werden können. Weiterhin kann Rauchen die durch antipsychotische Medikamente hervorgerufenen extrapyramidalen Nebenwirkungen verbessern, und es induziert das Zytochrom P4501A2, das auch an der Metabolisierung einiger Neuroleptika beteiligt ist. Zusammenfassend kann festgestellt werden, dass die Nikotinzufuhr bei Patienten mit schizophrenen Störungen eine Form der "Selbstmedikation" darstellen könnte, um Defizite im Bereich Aufmerksamkeit, Kognition und Informationsverarbeitung zu verbessern und um Nebenwirkungen von Antipsychotika zu reduzieren. Mögliche pharmakotherapeutische Ansätze zur Behandlung der gestörten Neurotransmission am nikotinergen Azetylcholinrezeptor werden diskutier
Ground State and Resonances in the Standard Model of Non-relativistic QED
We prove existence of a ground state and resonances in the standard model of
the non-relativistic quantum electro-dynamics (QED). To this end we introduce a
new canonical transformation of QED Hamiltonians and use the spectral
renormalization group technique with a new choice of Banach spaces.Comment: 50 pages change
Hadron calorimeter with MAPD readout in the NA61/SHINE experiment
The modular hadron calorimeter with micro-pixel avalanche photodiodes readout
for the NA61/SHINE experiment at the CERN SPS is presented. The calorimeter
consists of 44 independent modules with lead-scintillator sandwich structure.
The light from the scintillator tiles is captured by and transported with
WLS-fibers embedded in scintillator grooves. The construction provides a
longitudinal segmentation of the module in 10 sections with independent MAPD
readout. MAPDs with pixel density of /mm ensure good linearity of
calorimeter response in a wide dynamical range. The performance of the
calorimeter prototype in a beam test is reported
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