4,191 research outputs found
Symposium, Creditors\u27 Rights, Fees and Allowances to Attorneys in Bankruptcy and Chapter XI Proceedings
Symposium, Creditors\u27 Rights, Fees and Allowances to Attorneys in Bankruptcy and Chapter XI Proceedings
Operator ordering and Classical soliton path in Two-dimensional N=2 supersymmetry with Kahler potential
We investigate a 2-dimensional N=2 supersymmetric model which consists of n
chiral superfields with Kahler potential. When we define quantum observables,
we are always plagued by operator ordering problem. Among various ways to fix
the operator order, we rely upon the supersymmetry. We demonstrate that the
correct operator order is given by requiring the super Poincare algebra by
carrying out the canonical Dirac bracket quantization. This is shown to be also
true when the supersymmetry algebra has a central extension by the presence of
topological soliton. It is also shown that the path of soliton is a straight
line in the complex plane of superpotential W and triangular mass inequality
holds. And a half of supersymmetry is broken by the presence of soliton.Comment: 13 pages, typos correcte
The horizon problem for prevalent surfaces
We investigate the box dimensions of the horizon of a fractal surface defined
by a function . In particular we show that a prevalent surface
satisfies the `horizon property', namely that the box dimension of the horizon
is one less than that of the surface. Since a prevalent surface has box
dimension 3, this does not give us any information about the horizon of
surfaces of dimension strictly less than 3. To examine this situation we
introduce spaces of functions with surfaces of upper box dimension at most
\alpha, for \alpha [2,3). In this setting the behaviour of the horizon is
more subtle. We construct a prevalent subset of these spaces where the lower
box dimension of the horizon lies between the dimension of the surface minus
one and 2. We show that in the sense of prevalence these bounds are as tight as
possible if the spaces are defined purely in terms of dimension. However, if we
work in Lipschitz spaces, the horizon property does indeed hold for prevalent
functions. Along the way, we obtain a range of properties of box dimensions of
sums of functions
On the support of the Ashtekar-Lewandowski measure
We show that the Ashtekar-Isham extension of the classical configuration
space of Yang-Mills theories (i.e. the moduli space of connections) is
(topologically and measure-theoretically) the projective limit of a family of
finite dimensional spaces associated with arbitrary finite lattices. These
results are then used to prove that the classical configuration space is
contained in a zero measure subset of this extension with respect to the
diffeomorphism invariant Ashtekar-Lewandowski measure.
Much as in scalar field theory, this implies that states in the quantum
theory associated with this measure can be realized as functions on the
``extended" configuration space.Comment: 22 pages, Tex, Preprint CGPG-94/3-
On the use of non-canonical quantum statistics
We develop a method using a coarse graining of the energy fluctuations of an
equilibrium quantum system which produces simple parameterizations for the
behaviour of the system. As an application, we use these methods to gain more
understanding on the standard Boltzmann-Gibbs statistics and on the recently
developed Tsallis statistics. We conclude on a discussion of the role of
entropy and the maximum entropy principle in thermodynamics.Comment: 29 pages, uses iopart.cls, major revisions of text for better
readability, added a discussion about essentially microcanonical ensemble
Algebras generated by two bounded holomorphic functions
We study the closure in the Hardy space or the disk algebra of algebras
generated by two bounded functions, of which one is a finite Blaschke product.
We give necessary and sufficient conditions for density or finite codimension
of such algebras. The conditions are expressed in terms of the inner part of a
function which is explicitly derived from each pair of generators. Our results
are based on identifying z-invariant subspaces included in the closure of the
algebra. Versions of these results for the case of the disk algebra are given.Comment: 22 pages ; a number of minor mistakes have been corrected, and some
points clarified. Conditionally accepted by Journal d'Analyse Mathematiqu
Density of states of a two-dimensional electron gas in a non-quantizing magnetic field
We study local density of electron states of a two-dimentional conductor with
a smooth disorder potential in a non-quantizing magnetic field, which does not
cause the standart de Haas-van Alphen oscillations. It is found, that despite
the influence of such ``classical'' magnetic field on the average electron
density of states (DOS) is negligibly small, it does produce a significant
effect on the DOS correlations. The corresponding correlation function exhibits
oscillations with the characteristic period of cyclotron quantum
.Comment: 7 pages, including 3 figure
Fluorescence molecular tomography: Principles and potential for pharmaceutical research
Fluorescence microscopic imaging is widely used in biomedical research to study molecular and cellular processes in cell culture or tissue samples. This is motivated by the high inherent sensitivity of fluorescence techniques, the spatial resolution that compares favorably with cellular dimensions, the stability of the fluorescent labels used and the sophisticated labeling strategies that have been developed for selectively labeling target molecules. More recently, two and three-dimensional optical imaging methods have also been applied to monitor biological processes in intact biological organisms such as animals or even humans. These whole body optical imaging approaches have to cope with the fact that biological tissue is a highly scattering and absorbing medium. As a consequence, light propagation in tissue is well described by a diffusion approximation and accurate reconstruction of spatial information is demanding. While in vivo optical imaging is a highly sensitive method, the signal is strongly surface weighted, i.e., the signal detected from the same light source will become weaker the deeper it is embedded in tissue, and strongly depends on the optical properties of the surrounding tissue. Derivation of quantitative information, therefore, requires tomographic techniques such as fluorescence molecular tomography (FMT), which maps the three-dimensional distribution of a fluorescent probe or protein concentration. The combination of FMT with a structural imaging method such as X-ray computed tomography (CT) or Magnetic Resonance Imaging (MRI) will allow mapping molecular information on a high definition anatomical reference and enable the use of prior information on tissue’s optical properties to enhance both resolution and sensitivity. Today many of the fluorescent assays originally developed for studies in cellular systems have been successfully translated for experimental studies in animals. The opportunity of monitoring molecular processes non-invasively in the intact organism is highly attractive from a diagnostic point of view but even more so for the drug developer, who can use the techniques for proof-of-mechanism and proof-of-efficacy studies. This review shall elucidate the current status and potential of fluorescence tomography including recent advances in multimodality imaging approaches for preclinical and clinical drug development
Ionisation by quantised electromagnetic fields: The photoelectric effect
In this paper we explain the photoelectric effect in a variant of the
standard model of non relativistic quantum electrodynamics, which is in some
aspects more closely related to the physical picture, than the one studied in
[BKZ]: Now we can apply our results to an electron with more than one bound
state and to a larger class of electron-photon interactions. We will specify a
situation, where ionisation probability in second order is a weighted sum of
single photon terms. Furthermore we will see, that Einstein's equality
for the maximal kinetic energy of
the electron, energy of the photon and ionisation gap
is the crucial condition for these single photon terms to be nonzero.Comment: 59 pages, LATEX2
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