4,030 research outputs found
Analysis of Superoscillatory Wave Functions
Surprisingly, differentiable functions are able to oscillate arbitrarily
faster than their highest Fourier component would suggest. The phenomenon is
called superoscillation. Recently, a practical method for calculating
superoscillatory functions was presented and it was shown that superoscillatory
quantum mechanical wave functions should exhibit a number of counter-intuitive
physical effects. Following up on this work, we here present more general
methods which allow the calculation of superoscillatory wave functions with
custom-designed physical properties. We give concrete examples and we prove
results about the limits to superoscillatory behavior. We also give a simple
and intuitive new explanation for the exponential computational cost of
superoscillations.Comment: 20 pages, several figure
Hydrogen atom as an eigenvalue problem in 3D spaces of constant curvature and minimal length
An old result of A.F. Stevenson [Phys. Rev.} 59, 842 (1941)] concerning the
Kepler-Coulomb quantum problem on the three-dimensional (3D) hypersphere is
considered from the perspective of the radial Schr\"odinger equations on 3D
spaces of any (either positive, zero or negative) constant curvature. Further
to Stevenson, we show in detail how to get the hypergeometric wavefunction for
the hydrogen atom case. Finally, we make a comparison between the ``space
curvature" effects and minimal length effects for the hydrogen spectrumComment: 6 pages, v
Quantum Field Theory with Nonzero Minimal Uncertainties in Positions and Momenta
A noncommutative geometric generalisation of the quantum field theoretical
framework is developed by generalising the Heisenberg commutation relations.
There appear nonzero minimal uncertainties in positions and in momenta. As the
main result it is shown with the example of a quadratically ultraviolet
divergent graph in theory that nonzero minimal uncertainties in
positions do have the power to regularise. These studies are motivated with the
ansatz that nonzero minimal uncertainties in positions and in momenta arise
from gravity. Algebraic techniques are used that have been developed in the
field of quantum groups.Comment: 52 pages LATEX, DAMTP/93-33. Revised version now includes a chapter
on the Poincare algebra and curvature as noncommutativity of momentum spac
Apport de la biologie moléculaire dans le diagnostic des infections à Acinetobacter baumannii
Acinetobacter baumannii is an opportunistic pathogen responsible for severe nosocomial infections like pneumonia, especially in mechanically ventilated patients, bacteraemia, urinary infections or wound infections. This bacterium is able of causing outbreaks in hospitals. In addition, the number of strains resistant to carbapenems is increasing worldwide, explaining the fear it inspires to clinicians, especially those from intensive care units, because of difficult-to- treat infections. The management of A. baumannii infections is becoming a public health problem, it is therefore important to use fast and reliable tools to highlight abnormal phenomena in health care facilities. The interest in molecular biology in diagnosis of A. baumannii infections and in detection of epidemics has been demonstrated for many years in the scientific literature. We present here some molecular techniques for detection of this bacterium
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