title:
He Scattering from Random Adsorbates, Disordered Compact Islands and
  Fractal Submonolayers: Intensity Manifestations of Surface Disorder

abstract:
  A theoretical study is made on He scattering from three fundamental classes
of disordered ad-layers: (a) Translationally random adsorbates, (b) disordered
compact islands and (c) fractal submonolayers. The implications of the results
to experimental studies of He scattering from disordered surfaces are
discussed, and a combined experimental-theoretical study is made for Ag
submonolayers on Pt(111). Some of the main theoretical findings are: (1)
Structural aspects of the calculated intensities from translationally random
clusters were found to be strongly correlated with those of individual
clusters. (2) Low intensity Bragg interference peaks appear even for scattering
from very small ad-islands, and contain information on the ad-island local
electron structure. (3) For fractal islands, just as for islands with a
different structure, the off-specular intensity depends on the parameters of
the He/Ag interaction, and does not follow a universal power law as previously
proposed in the literature. In the experimental-theoretical study of Ag on
Pt(111), we use first experimental He scattering data from low-coverage (single
adsorbate) systems to determine an empirical He/Ag-Pt potential of good
quality. Then, we carry out He scattering calculations for high coverage and
compare with experiments. The conclusions are that the actual experimental
phase corresponds to small compact Ag clusters of narrow size distribution,
translationally disordered on the surface.


title:
One Dimensional Nonlinear Wake-fields Excited in a Cold Plasma by
  Charged Bunches

abstract:
  One dimensional nonlinear plasma wake-fields excited by a single bunch and by
series of bunches are considered. Essential differences are brought to light
between negatively charged bunch case and positively one. The bunches with
nonuniform distributions of density are investigated. The obtained results show
dependence of excited potential electric fields on bunches parameters and
allows to choose these parameters optimal.


title:
Mechanical interpretation of existence theorems in a nonlinear Dirichlet
  problem

abstract:
  The existence of radial solutions of a nonlinear Dirichlet problem in a ball
is translated to the language of Mechanics, i.e. to requirements on the time of
motion of a particle in an external potential and under the action of a
viscosity force. This approach reproduces existing theorems and, in principle,
provides a method for the analysis of the general case. Examples of new
theorems are given, which prove the usefulness of this qualitative method.


title: Linear Scaling Solution of the Coulomb problem using wavelets

abstract:
  The Coulomb problem for continuous charge distributions is a central problem
in physics. Powerful methods, that scale linearly with system size and that
allow us to use different resolutions in different regions of space are
therefore highly desirable. Using wavelet based Multi Resolution Analysis we
derive for the first time a method which has these properties. The power and
accuracy of the method is illustrated by applying it to the calculation of of
the electrostatic potential of a full three-dimensional all-electron Uranium
dimer.


title: Optical Properties of Deep Ice at the South Pole - Absorption

abstract:
  We discuss recent measurements of the wavelength-dependent absorption
coefficients in deep South Pole ice. The method uses transit time distributions
of pulses from a variable-frequency laser sent between emitters and receivers
embedded in the ice. At depths of 800 to 1000 m scattering is dominated by
residual air bubbles, whereas absorption occurs both in ice itself and in
insoluble impurities. The absorption coefficient increases approximately
exponentially with wavelength in the measured interval 410 to 610 nm. At the
shortest wavelength our value is about a factor 20 below previous values
obtained for laboratory ice and lake ice; with increasing wavelength the
discrepancy with previous measurements decreases. At around 415 to 500 nm the
experimental uncertainties are small enough for us to resolve an extrinsic
contribution to absorption in ice: submicron dust particles contribute by an
amount that increases with depth and corresponds well with the expected
increase seen near the Last Glacial Maximum in Vostok and Dome C ice cores. The
laser pulse method allows remote mapping of gross structure in dust
concentration as a function of depth in glacial ice.


title:
Monte Carlo Implementation of Gaussian Process Models for Bayesian
  Regression and Classification

abstract:
  Gaussian processes are a natural way of defining prior distributions over
functions of one or more input variables. In a simple nonparametric regression
problem, where such a function gives the mean of a Gaussian distribution for an
observed response, a Gaussian process model can easily be implemented using
matrix computations that are feasible for datasets of up to about a thousand
cases. Hyperparameters that define the covariance function of the Gaussian
process can be sampled using Markov chain methods. Regression models where the
noise has a t distribution and logistic or probit models for classification
applications can be implemented by sampling as well for latent values
underlying the observations. Software is now available that implements these
methods using covariance functions with hierarchical parameterizations. Models
defined in this way can discover high-level properties of the data, such as
which inputs are relevant to predicting the response.


title: Three-potential formalism for the atomic three-body problem

abstract:
  Based on a three-potential formalism we propose mathematically well-behaved
Faddeev-type integral equations for the atomic three-body problem and descibe
their solutions in Coulomb-Sturmian space representation. Although the system
contains only long-range Coulomb interactions these equations allow us to reach
solution by approximating only some auxiliary short-range type potentials. We
outline the method for bound states and demonstrate its power in benchmark
calculations. We can report a fast convergence in angular momentum channels.


title: Multiphoton detachment of electrons from negative ions

abstract:
  A simple analytical solution for the problem of multiphoton detachment from
negative ions by a linearly polarized laser field is found. It is valid in the
wide range of intensities and frequencies of the field, from the perturbation
theory to the tunneling regime, and is applicable to the excess-photon as well
as near-threshold detachment. Practically, the formulae are valid when the
number of photons is greater than two. They produce the total detachment rates,
relative intensities of the excess-photon peaks, and photoelectron angular
distributions for the hydrogen and halogen negative ions, in agreement with
those obtained in other, more numerically involved calculations in both
perturbative and non-perturbative regimes. Our approach explains the extreme
sensitivity of the multiphoton detachment probability to the asymptotic
behaviour of the bound-state wave function. Rapid oscillations in the angular
dependence of the $n$-photon detachment probability are shown to arise due to
interference of the two classical trajectories which lead to the same final
state after the electron emerges at the opposite sides of the atom when the
field is close to maximal.


title: Multiphoton detachment from negative ions: new theory vs experiment

abstract:
  In this paper we compare the results of our adiabatic theory (Gribakin and
Kuchiev, Phys. Rev. A, accepted for publication) with other theoretical and
experimental results, mostly for halogen negative ions. The theory is based on
the Keldysh approach. It shows that the multiphoton detachment rates and the
corresponding n-photon detachment cross sections depend only on the asymptotic
behaviour of the bound state radial wave function. The dependence on the
exponent is very strong. This is the main reason for the disagreement with some
previous calculations, which employed bound state wave functions with incorrect
asymptotic forms. In a number of cases our theoretical results produces best
agreement with absolute and relative experimental data.


title:
Comment on ``Boson-realization model for the vibrational spectra of
  tetrahedral molecules''

abstract:
  An algebraic model in terms of a local harmonic boson realization was
recently proposed to study molecular vibrational spectra [Zhong-Qi Ma et al.,
Phys. Rev. A 53, 2173 (1996)]. Because of the local nature of the bosons the
model has to deal with spurious degrees of freedom. An approach to eliminate
the latter from both the Hamiltonian and the basis was suggested. We show that
this procedure does not remove all spurious components from the Hamiltonian and
leads to a restricted set of interactions. We then propose a scheme in which
the physical Hamiltonian can be systematically constructed up to any order
without the need of imposing conditions on its matrix elements. In addition, we
show that this scheme corresponds to the harmonic limit of a symmetry adapted
algebraic approach based on U(2) algebras.


abstract:
  Book Review of Quantum Field Theory by Lewis H. Ryder. An observation on
Ryder's derivation of Dirac equation is made. The review ends as, "A rare
combination of a thorough understanding and appreciation of the essential
logical structure of quantum field theory and deep pedagogic skills have
intermingled to create a masterpiece on the elementary introduction to quantum
field theory in less than five hundred pages... . Without reservations, I give
my strongest recommendation to every beginning student of physics to acquire
and read Quantum Field Theory by L. H. Ryder."


title: Vorticity Generation in Slow Cooling Flows

abstract:
  We show that any generic non-adiabatic slow flow of ideal compressible fluid
develops a significant vorticity. As an example, an initially irrotational
conductive cooling flow is considered. A perturbation theory for the vorticity
generation is developed that employs, as a zero order solution, a novel
two-dimensional similarity solution. Full gasdynamic simulations of this CF
demonstrate the vorticity generation and support the theory. The relevance of
this problem to the experiments with the "hot channels" is discussed.

categories: physics.flu-dyn nlin.PS patt-sol physics.plasm-ph


title: Collisional Semiclassical Aproximations in Phase-Space Representation

abstract:
  The Gaussian Wave-Packet phase-space representation is used to show that the
expansion in powers of $\hbar$ of the quantum Liouville propagator leads, in
the zeroth order term, to results close to those obtained in the statistical
quasiclassical method of Lee and Scully in the Weyl-Wigner picture. It is also
verified that propagating the Wigner distribution along the classical
trajectories the amount of error is less than that coming from propagating the
Gaussian distribution along classical trajectories.


title: Two-pion correlations in Au+Au collisions at 10.8 GeV/c per nucleon

abstract:
  Two-particle correlation functions for positive and negative pions have been
measured in Au+Au collisions at 10.8~GeV/c per nucleon. The data were analyzed
using one- and three-dimensional correlation functions. From the results of the
three-dimensional fit the phase space density of pions was calculated. It is
consistent with local thermal equilibrium.


title:
The determination of shock ramp width using the noncoplanar magnetic
  field component

abstract:
  We determine a simple expression for the ramp width of a collisionless fast
shock, based upon the relationship between the noncoplanar and main magnetic
field components. By comparing this predicted width with that measured during
an observation of a shock, the shock velocity can be determined from a single
spacecraft. For a range of low-Mach, low-beta bow shock observations made by
the ISEE-1 and -2 spacecraft, ramp widths determined from two-spacecraft
comparison and from this noncoplanar component relationship agree within 30%.
When two-spacecraft measurements are not available or are inefficient, this
technique provides a reasonable estimation of scale size for low-Mach shocks.


title: "Falling cat" connections and the momentum map

abstract:
  We consider a standard symplectic dynamics on TM generated by a natural
Lagrangian L. The Lagrangian is assumed to be invariant with respect to the
action TR_g of a Lie group G lifted from the free and proper action R_g of G on
M. It is shown that under these conditions a connection on principal bundle pi:
M \rightarrow M/G can be constructed based on the momentum map corresponding to
the action TR_g. The horizontal motion is shown to be in physical terms the one
with all the momenta corresponding to the symmetry vanishing. A simple explicit
formula for the connection form is given. For the special case of the standard
action of G = SO(3) on M = R^3 x ... x R^3 corresponding to a rigid rotation of
a N-particle system the formula obtained earlier by Guichardet and
Shapere/Wilczek is reproduced.


title:
Interpretation of a low-lying excited state of the reaction center of
  Rb.sphaeroides as a double triplet

abstract:
  The recently observed transient absorption of the lowest excited state of the
special pair P* at 2710 cm-1 is assigned as a singlet which arises from the
coupling of the two lowest triplets from the two dimer halves. INDO
calculations are used to predict its intensity. The analogy of the coupling
mechanism to the trip-doublet spectrum from P+ is shown and the influence of
the double triplet on the Stark effect of P* is investigated.


title:
A Simple Method for Calculating Quantum Effects on the Temperature
  Dependence of Bimolecular Reaction Rates: An Application to $CH_4 + H \to
  CH_3 + H_2$

abstract:
  The temperature dependence of the rate of the reaction CH_4+H \to CH_3+H_2 is
studied using classical collision theory with a temperature-dependent effective
potential derived from a path integral analysis. Analytical expressions are
obtained for the effective potential and for the rate constant. The rate
constant expressions use a temperature-dependent activation energy. They give
better agreement with the available experimental results than do previous
empirical fits. Since all but one of the parameters in the present expressions
are obtained from theory, rather than by fitting to experimental reaction
rates, the expressions can be expected to be more dependable than purely
empirical expressions at temperatures above 2000 K or below 350 K, where
experimental results are not available.


title:
Modified Laplace transformation method and its application to the
  anharmonic oscillator

abstract:
  We apply a recently proposed approximation method to the evaluation of
non-Gaussian integral and anharmonic oscillator. The method makes use of the
truncated perturbation series by recasting it via the modified Laplace integral
representation. The modification of the Laplace transformation is such that the
upper limit of integration is cut off and an extra term is added for the
compensation. For the non-Gaussian integral, we find that the perturbation
series can give accurate result and the obtained approximation converges to the
exact result in the $N \to \infty$ limit ($N$ denotes the order of perturbation
expansion). In the case of anharmonic oscillator, we show that several order
result yields good approximation of the ground state energy over the entire
parameter space. The large order aspect is also investigated for the anharmonic
oscillator.


title: Aging Random Walks

abstract:
  Aging refers to the property of two-time correlation functions to decay very
slowly on (at least) two time scales. This phenomenon has gained recent
attention due to experimental observations of the history dependent relaxation
behavior in amorphous materials (``Glasses'') which pose a challenge to
theorist. Aging signals the breaking of time-translational invariance and the
violation of the fluctuation dissipation theorem during the relaxation process.
But while the origin of aging in disordered media is profound, and the
discussion is clad in the language of a well-developed theory, systems as
simple as a random walk near a wall can exhibit aging. Such a simple walk
serves well to illustrate the phenomenon and some of the physics behind it.


title: Quasi-exactly Solvable Lie Superalgebras of Differential Operators

abstract:
  In this paper, we study Lie superalgebras of $2\times 2$ matrix-valued
first-order differential operators on the complex line. We first completely
classify all such superalgebras of finite dimension. Among the
finite-dimensional superalgebras whose odd subspace is nontrivial, we find
those admitting a finite-dimensional invariant module of smooth vector-valued
functions, and classify all the resulting finite-dimensional modules. The
latter Lie superalgebras and their modules are the building blocks in the
construction of QES quantum mechanical models for spin 1/2 particles in one
dimension.


title: High Energy Colliders

abstract:
  We consider the high energy advantages, disadvantages and luminosity
requirements of hadrons, leptons and photon-photon colliders. Technical
problems in obtaining increased energy in each type of machine are presented.
The machines relative size are also discussed.


title: Muon-Muon and other High Energy Colliders

abstract:
  Parameters are given of 4 TeV and 0.5 TeV (c-of-m) high luminosity muon-muon
Colliders. We discuss the various systems, starting from the proton accelerator
needed to generate the muons and proceeding through muon cooling, acceleartion
and storage in a collider ring. Detector background, polarization are analyzed.
We also look at other type of colliders (hadron, lepton and photon-photon) for
comparison. Technical problems in obtaining increased energy in each type of
machine are presented. Their relative size and probable relative costs are
discussed.


title: Mean Field Approach to Quantum Duffing Oscillator

abstract:
  We propose a mean-field approach to the Duffing oscillator to construct
perturbatively the bounded operators that generate the quantum states, and to
define a non-Gaussian density operator.


title: Integration over a generic algebra

abstract:
  In this paper we consider the problem of quantizing theories defined over
configuration spaces described by non-commuting parameters. If one tries to do
that by generalizing the path-integral formalism, the first problem one has to
deal with is the definition of integral over these generalized configuration
spaces. This is the problem we state and solve in the present work, by
constructing an explicit algorithm for the integration over a general algebra.
Many examples are discussed in order to illustrate our construction.


title:
Free electron approximation for electron states of poly($p$-phenylene
  vinylene) and other conjugated systems

abstract:
  Free electron approximation for electron states in poly($p$-phenylene
vinylene) and other conjugated systems is developed. It provides simple and
clear analytical expressions for energies of electron states and for wave
functions. The results are in quantitative agreement with experiments. Our
model does not contain fitting parameters. We present two examples of the
developed theory applications: exact calculation of electron energy in magnetic
field, and scattering of electrons in copolymer.


title:
Simultaneously Dissipative Operators And The Infinitesimal Moore Effect
  In Interval Spaces

abstract:
  One of shortcomings of stepwise interval methods is the following. The
intervals determining the solution of a system are often expanded in the course
of time irrespective of the method and step used (the {\em Moore effect}). We
introduce the notion of general {\em interval spaces} and study the
infinitesimal Moore effect (IME) in these spaces. We obtain the local
conditions of absence of the IME in terms of Jacobi matrices field. The
relation between the absence of IME and simultaneous dissipativity of the
Jacobi matrices is established. We study simultaneously dissipative operators
in $\Bbb{R}^n$. A linear operator $A$ is {\em dissipative} with respect to a
norm $\|...\|$ if $\| \exp (At) \| \leq 1$ at all $t \geq 0$. For each norm,
the dissipative operator form a closed convex cone. An operator $A$ is {\em
stable dissipative} if it belongs to the interior of this cone. The family of
linear operators $\{A_\alpha \}$ is called {\em simultaneously dissipative}, if
there exists a norm with respect to which all the operators are dissipative. We
studied general properties of such families. For example, let the family
$\{A_\alpha \}$ be finite and generate a nilpotent Lee algebra and let for each
$A_\alpha$ there exist a norm with respect to which it is dissipative. Then
$\{A_\alpha \}$ is simultaneously dissipative. Let the family $\{A_\alpha \}$
be compact and generate solvable Lee algebra, and let the spectrum of each
operator $A_\alpha $ lie in the open left half-plane. Then $\{A_\alpha \}$ is
simultaneously stable dissipative, i.e. there exists a norm with respect to
which all $A_\alpha $ are stable dissipative. We study the conditions of
simultaneous dissipativity of the matrices of rank one and discussed their
application to equations of {\em mass action law} kinetics.


title:
Boundary Integral Method for Stationary States of Two-Dimensional
  Quantum Systems

abstract:
  The boundary integral method for calculating the stationary states of a
quantum particle in nano-devices and quantum billiards is presented in detail
at an elementary level. According to the method, wave functions inside the
domain of the device or billiard are expressed in terms of line integrals of
the wave function and its normal derivative along the domain's boundary; the
respective energy eigenvalues are obtained as the roots of Fredholm
determinants. Numerical implementations of the method are described and applied
to determine the energy level statistics of billiards with circular and stadium
shapes and demonstrate the quantum mechanical characteristics of chaotic
motion. The treatment of other examples as well as the advantages and
limitations of the boundary integral method are discussed.


title: Introduction to the Diffusion Monte Carlo Method

abstract:
  A self-contained and tutorial presentation of the diffusion Monte Carlo
method for determining the ground state energy and wave function of quantum
systems is provided. First, the theoretical basis of the method is derived and
then a numerical algorithm is formulated. The algorithm is applied to determine
the ground state of the harmonic oscillator, the Morse oscillator, the hydrogen
atom, and the electronic ground state of the H2+ ion and of the H2 molecule. A
computer program on which the sample calculations are based is available upon
request.


title:
Partnerships For Physics Teaching Reform -- a crucial role for
  universities and colleges

abstract:
  To meet National Standards recommended by the National Research Council for
high school physics, inservice teachers must be integrated into the physics
community. They must be empowered by access to resources of the physics
community and by sustained support for their professional development. To that
end, university and college physics departments must assume an essential role
in establishing and maintaining the necessary local infrastructure.
Nevertheless, this can be done within their current systems at negligible cost
by forming partnerships with local alliances of inservice teachers. Practical
details have been worked out, and working partnerships have been established in
several localities. This effort should be extended to a national infrastructure
for reform of physics teaching in community colleges as well as in high
schools. Most teachers are eager to participate in teaching reform.


title: Path integrals for a class of p-adic Schr"odinger equations

abstract:
  The theme of doing quantum mechanics on all abelian groups goes back to
Schwinger and Weyl. If the group is a vector space of finite dimension over a
non-archimedean locally compact division ring, it is of interest to examine the
structure of dynamical systems defined by Hamiltonians analogous to those
encountered over the field of real numbers. In this letter a path integral
formula for the imaginary time propagators of these Hamiltonians is derived.


title: Space, Time and Superluminal Particles

abstract:
  If textbook Lorentz invariance is actually a property of the equations
describing a sector of matter above some critical distance scale, several
sectors of matter with different critical speeds in vacuum can coexist and an
absolute rest frame (the vacuum rest frame, possibly related to the local rest
frame of the expanding Universe) may exist without contradicting the apparent
Lorentz invariance felt by "ordinary" particles (particles with critical speed
in vacuum equal to c , the speed of light). The real geometry of space-time
will then be different from standard Lorentz invariance, and the Poincare
relativity principle will be a local (in space and time), approximate sectorial
property. It seems natural to assume that particles with critical speed in
vacuum different from c are superluminal. We illustrate such a scenario using
as an example a spinorial space-time where the modulus of the spinor,
associated to the time variable, is the size of an expanding Universe. Several
properties of superluminal particles, and of matter without a universal
relativity principle, are discussed in view of experimental applications. If
the vacuum rest frame is close to that suggested by the cosmic microwave
background, experimental searches for superluminal particles on earth should
mainly contemplate a laboratory speed range around 10E3 c , even for very high
energy superluminal cosmic rays. The detectability of several consequences of
the new scenario is briefly discussed.


title:
Radiative Corrections to the 2E1 Decay Rate of the 2s-State in
  Hydrogen-Like Atoms

abstract:
  Radiative corrections to the 2E1 decay width of the 2s-state in the low-Z
hydrogen-like system are examined within logarithmic approximation. The
correction is found to be 2.025(1) alpha (Z alpha)^2 / pi log(Z alpha)^2 in
units of the non-relativistic rate.


title: Radiative Corrections to the Light Muonic Atoms Decay Rate

abstract:
  Radiative corrections to the decay rate in the low-Z hydrogen-like muonic
atoms are considered. The correction arises from the Uehling potential and it
has the relative order of alpha. The numerical results are reported for the
2p-1s transition for the atom with the nuclear charge value up to Z=10.


title: Form Invariance of Differential Equations in General Relativity

abstract:
  Einstein equations for several matter sources in Robertson-Walker and Bianchi
I type metrics, are shown to reduce to a kind of second order nonlinear
ordinary differential equation $\ddot{y}+\alpha f(y)\dot{y}+\beta f(y)\int{f(y)
dy}+\gamma f(y)=0$. Also, it appears in the generalized statistical mechanics
for the most interesting value q=-1. The invariant form of this equation is
imposed and the corresponding nonlocal transformation is obtained. The
linearization of that equation for any $\alpha, \beta$ and $\gamma$ is
presented and for the important case $f=by^n+k$ with $\beta=\alpha ^2
(n+1)/((n+2)^2)$ its explicit general solution is found. Moreover, the form
invariance is applied to yield exact solutions of same other differential
equations.


title: Homogeneous phase spaces: the Cayley-Klein framework

abstract:
  The metric structure of homogeneous spaces of rank-one and rank-two
associated to the real pseudo-orthogonal groups SO(p,q) and some of their
contractions (e.g., ISO(p,q), Newton-Hooke type groups...) is studied. All
these spaces are described from a unified setting following a Cayley-Klein
scheme allowing to simultaneously study the main features of their Riemannian,
pesudoRiemannian and semiRiemannian metrics, as well as of their curvatures.
Some of the rank-one spaces are naturally interpreted as spacetime models.
Likewise, the same natural interpretation for rank-two spaces is as spaces of
lines in rank-one spaces; through this relation these rank-two spaces give rise
to homogeneous phase space models. The main features of the phase spaces for
homogeneous spacetimes are analysed.


title:
"Cayley-Klein" schemes for real Lie algebras and Freudhental Magic
  Squares

abstract:
  We introduce three "Cayley-Klein" families of Lie algebras through
realizations in terms of either real, complex or quaternionic matrices. Each
family includes simple as well as some limiting quasi-simple real Lie algebras.
Their relationships naturally lead to an infinite family of $3\times 3$
Freudenthal-like magic squares, which relate algebras in the three CK families.
In the lowest dimensional cases suitable extensions involving octonions are
possible, and for $N=1, 2$, the "classical" $3\times 3$ Freudenthal-like
squares admit a $4\times 4$ extension, which gives the original Freudenthal
square and the Sudbery square.


title:
Casimir invariants for the complete family of quasi-simple orthogonal
  algebras

abstract:
  A complete choice of generators of the center of the enveloping algebras of
real quasi-simple Lie algebras of orthogonal type, for arbitrary dimension, is
obtained in a unified setting. The results simultaneously include the well
known polynomial invariants of the pseudo-orthogonal algebras $so(p,q)$, as
well as the Casimirs for many non-simple algebras such as the inhomogeneous
$iso(p,q)$, the Newton-Hooke and Galilei type, etc., which are obtained by
contraction(s) starting from the simple algebras $so(p,q)$. The dimension of
the center of the enveloping algebra of a quasi-simple orthogonal algebra turns
out to be the same as for the simple $so(p,q)$ algebras from which they come by
contraction. The structure of the higher order invariants is given in a
convenient "pyramidal" manner, in terms of certain sets of "Pauli-Lubanski"
elements in the enveloping algebras. As an example showing this approach at
work, the scheme is applied to recovering the Casimirs for the (3+1)
kinematical algebras. Some prospects on the relevance of these results for the
study of expansions are also given.


title:
Unified Octonionic Representation of the 10-13 Dimensions Clifford
  Algebra

abstract:
  We give a one dimensional octonionic representation of the different Clifford
algebra $Cliff(5,5)\sim Cliff(1,9), Cliff(6,6)\sim Cliff(2,10)$ and lastly
$Cliff(7,6)\sim Cliff(3,10)$.


title: Transmission properties of the X-ray window for the SIXA spectrometer

abstract:
  The ultrathin X-ray entrance window for the spaceborne spectrometer SIXA was
characterised using synchrotron radiation. X-ray absorption fine structure near
the absorption edges of the constituting elements (aluminium, carbon, oxygen
and nitrogen) was measured. Large scale positional variations were also
studied. In addition, the opacity of the window was tested by observing the
effect of photocurrent in the detector generated by light leaked through the
window.


title: A calculation with a bi-orthogonal wavelet transformation

abstract:
  We explore the use of bi-orthogonal basis for continuous wavelet
transformations, thus relaxing the so-called admissibility condition on the
analyzing wavelet. As an application, we determine the eigenvalues and
corresponding radial eigenfunctions of the Hamiltonian of relativistic
Hydrogen-like atoms.


title: Numerical Study on Space-Time Pulse Compression

abstract:
  A numerical study of the properties of Gaussian pulses propagating in planar
waveguide under the combined effect of positive Kerr-type nonlinearity,
diffraction in planar waveguides and anomalous or normal dispersion, is
presented. It is demonstrated how the relative strength of dispersion and
diffraction, the strength of nonlinearity and the initial spatial and temporal
pulse chirps effect on the parameters of pulse compression, such as the maximal
compression factor and the distance to the point of maximal compression.


title: Characterising a Si(Li) detector element for the SIXA X-ray spectrometer

abstract:
  The detection efficiency and response function of a Si(Li) detector element
for the SIXA spectrometer have been determined in the 500 eV to 5 keV energy
range using synchrotron radiation emitted at a bending magnet of the electron
storage ring BESSY, which is a primary radiation standard. The agreement
between the measured spectrum and the model calculation is better than 2%.
  PACS: 95.55.Ka; 07.85.Nc; 29.40.Wk; 85.30.De
  Keywords: Si(Li) detectors, X-ray spectrometers, detector calibration, X-ray
response, spectral lineshape


title: The Quantum Field Theory of Physics and Mathematics

abstract:
  A discussion of different criteria of consistency of quantum field theory
from the point of view of physics and mathematics.


title: A note on the light velocity anisotropy

abstract:
  In the framework of linear transformations between inertial systems, there
are no physical reasons for assuming any anisotropy in the one-way velocity of
light.


title: Foundations of Statistical Mechanics and Theory of Phase Transition

abstract:
  A new formulation of statistical mechanics is put forward according to which
a random variable characterizing a macroscopic body is postulated to be
infinitely divisible. It leads to a parametric representation of partition
function of an arbitrary macroscopic body, a possibility to describe a
macroscopic body under excitation by a gas of some elementary quasiparticles
etc. A phase transition is defined as such a state of a macroscopic body that
its random variable is stable in sense of L\'evy. From this definition it
follows by deduction all general properties of phase transitions: existence of
the renormalization semigroup, the singularity classification for thermodynamic
functions, the phase transition universality and universality classes. On this
basis we has also built a 2-parameter scaling theory of phase transitions, a
thermodynamic function for the Ising model etc.


title:
Canonically Relativistic Quantum Mechanics: Representations of the
  Unitary Semidirect Heisenberg Group, U(1,3) *s H(1,3)

abstract:
  Born proposed a unification of special relativity and quantum mechanics that
placed position, time, energy and momentum on equal footing through a
reciprocity principle and extended the usual position-time and energy-momentum
line elements to this space by combining them through a new fundamental
constant. Requiring also invariance of the symplectic metric yields U(1,3) as
the invariance group, the inhomogeneous counterpart of which is the canonically
relativistic group CR(1,3) = U(1,3) *s H(1,3) where H(1,3) is the Heisenberg
Group in 4 dimensions and "*s" is the semidirect product. This is the
counterpart in this theory of the Poincare group and reduces in the appropriate
limit to the expected special relativity and classical Hamiltonian mechanics
transformation equations. This group has the Poincare group as a subgroup and
is intrinsically quantum with the Position, Time, Energy and Momentum operators
satisfying the Heisenberg algebra. The representations of the algebra are
studied and Casimir invariants are computed. Like the Poincare group, it has a
little group for a ("massive") rest frame and a null frame. The former is U(3)
which clearly contains SU(3) and the latter is Os(2) which contains SU(2)*U(1).


title: Stabilization of tilt order by chain flexibility in Langmuir monolayers

abstract:
  Langmuir monolayers are modeled as systems of short chains, which are
confined to a planar surface at one end, but free to move within the plane. The
phase behavior is calculated in a mean field approximation, which combines the
self consistent field method with elements of classical density functional
theory. It is shown that phases with tilt order are unstable in systems of
stiff chains, but can be stabilized by chain conformational entropy in systems
of sufficiently flexible chains. The chain entropy is also responsible for the
appearance of an additional untilted phase, the liquid expanded phase. The
region of stability of the different phases is discussed, and their microscopic
structure is analyzed in some detail.


title:
Diblock copolymers at a homopolymer-homopolymer-interface: a Monte Carlo
  simulation

abstract:
  The properties of diluted symmetric A-B diblock copolymers at the interface
between A and B homopolymer phases are studied by means of Monte Carlo (MC)
simulations of the bond fluctuation model. We calculate segment density
profiles as well as orientational properties of segments, of A and B blocks,
and of the whole chain. Our data support the picture of oriented ``dumbbells'',
which consist of mildly perturbed A and B Gaussian coils. The results are
compared to a self consistent field theory (SCFT) for single copolymer chains
at a homopolymer interface. We also discuss the number of interaction contacts
between monomers, which provide a measure for the ``active surface'' of
copolymers or homopolymers close to the interface.


title: Photodetachment study of the 1s3s4s ^4S resonance in He^-

abstract:
  A Feshbach resonance associated with the 1s3s4s ^{4}S state of He^{-} has
been observed in the He(1s2s ^{3}S) + e^- (\epsilon s) partial photodetachment
cross section. The residual He(1s2s ^{3}S) atoms were resonantly ionized and
the resulting He^+ ions were detected in the presence of a small background. A
collinear laser-ion beam apparatus was used to attain both high resolution and
sensitivity. We measured a resonance energy E_r = 2.959 255(7) eV and a width
\Gamma = 0.19(3) meV, in agreement with a recent calculation.


title: The electron affinity of tellurium

abstract:
  The electron affinity of tellurium has been determined to 1.970 876(7) eV.
The threshold for photodetachment of Te^-(^{2} P_{3/2}) forming neutral Te in
the ground state was investigated by measuring the total photodetachment cross
section using a collinear laser-ion beam geometry. The electron affinity was
obtained from a fit to the Wigner law in the threshold region.


title: Electron affinity of Li: A state-selective measurement

abstract:
  We have investigated the threshold of photodetachment of Li^- leading to the
formation of the residual Li atom in the $2p ^2P$ state. The excited residual
atom was selectively photoionized via an intermediate Rydberg state and the
resulting Li^+ ion was detected. A collinear laser-ion beam geometry enabled
both high resolution and sensitivity to be attained. We have demonstrated the
potential of this state selective photodetachment spectroscopic method by
improving the accuracy of Li electron affinity measurements an order of
magnitude. From a fit to the Wigner law in the threshold region, we obtained a
Li electron affinity of 0.618 049(20) eV.


title: Quantum-Classical System: Simple Harmonic Oscillator

abstract:
  Problems concerning with application of quantum rules on classical phenomena
have been widely studied, for which lifted up the idea about quantization and
uncertainty principle. Energy quantization on classical example of simple
harmonic oscillator has been reviewed in this paper.


title: Resonance structure in the Li^- photodetachment cross section

abstract:
  We report on the first observation of resonance structure in the total cross
section for the photodetachment of Li^-. The structure arises from the
autodetaching decay of doubly excited ^1P states of Li^- that are bound with
respect to the 3p state of the Li atom. Calculations have been performed for
both Li^- and H^- to assist in the identification of these resonances. The
lowest lying resonance is a symmetrically excited intrashell resonance. Higher
lying asymmetrically excited intershell states are observed which converge on
the Li(3p) limit.


title: Gauge-potential approach to the kinematics of a moving car

abstract:
  A kinematics of the motion of a car is reformulated in terms of the theory of
gauge potentials (connection on principal bundle). E(2)-connection originates
in the no-slipping contact of the car with a road.


title: Wigner's Sisters

abstract:
  Paul A. M. Dirac was a great physicist. Wigner used to call him ``my famous
brother-in-law''. How did they become brothers-in-law? Did these two great
physicists have the same view toward physics?

categories: physics.hist-ph hep-ph hep-th nucl-th quant-ph


title: Wire scanners in low energy accelerators

abstract:
  Fast wire scanners are today considered as part of standard instrumentation
in high energy synchrotrons. The extension of their use to synchrotrons working
at lower energies, where Coulomb scattering can be important and the transverse
beam size is large, introduces new complications considering beam heating of
the wire, composition of the secondary particle shower and geometrical
consideration in the detection set-up. A major problem in treating these
effects is that the creation of secondaries in a thin carbon wire by a
energetic primary beam is difficult to describe in an analytical way. We are
here presenting new results from a full Monte Carlo simulation of this process
yielding information on heat deposited in the wire, particle type and energy
spectrum of secondaries and angular dependence as a function of primary beam
energy. The results are used to derive limits for the use of wire scanners in
low energy accelerators.


title:
Quasi-Hamiltonian Equations of Motion for Internal Coordinate Molecular
  Dynamics of Polymers

abstract:
  Conventional molecular dynamics simulations macromolecules require long
computational times because the most interesting motions are very slow compared
with the fast oscillations of bond lengths and bond angles that limit the
integration time step. Simulation of dynamics in the space of internal
coordinates, that is with bond lengths, bond angles and torsions as independent
variables, gives a theoretical possibility to eliminate all uninteresting fast
degrees of freedom from the system. This paper presents a new method for
internal coordinate molecular dynamics simulations of macromolecules. Equations
of motion are derived which are applicable to branched chain molecules with any
number of internal degrees of freedom. Equations use the canonical variables
and they are much simpler than existing analogs. In the numerical tests the
internal coordinate dynamics are compared with the traditional Cartesian
coordinate molecular dynamics in simulations a 56 residue globular protein. It
is shown that the traditional and internal coordinate dynamics require the same
time step size for the same accuracy and that in the standard geometry
approximation of amino acids, that is with fixed bond lengths, bond angles and
rigid aromatic groups, the characteristic step size is 4 fsec, that is two
times higher than with fixed bond lengths only. The step size can be increased
up to 11 fsec when rotation of hydrogen atoms is suppressed.


title: Lorentz Invariance and Superluminal Particles

abstract:
  If textbook Lorentz invariance is actually a property of the equations
describing a sector of matter above some critical distance scale, several
sectors of matter with different critical speeds in vacuum can coexist and an
absolute rest frame (the vacuum rest frame, possibly related to the local rest
frame of the expanding Universe) may exist without contradicting the apparent
Lorentz invariance felt by "ordinary" particles (particles with critical speed
in vacuum equal to $c$ , the speed of light). Sectorial Lorentz invariance,
reflected by the fact that all particles of a given dynamical sector have the
same critical speed in vacuum, will then be an expression of a fundamental
sectorial symmetry (e.g. preonic grand unification or extended supersymmetry)
protecting a parameter of the equations of motion. We study the breaking of
Lorentz invariance in such a scenario, with emphasis on mixing between the
"ordinary" sector and a superluminal sector, and discuss with examples the
consequences of existing data. The sectorial universality of the value of the
high-energy speed in vacuum, even exact, does not necessarily imply that
Lorentz invariance is not violated and does not by itself exclude the
possibility to produce superluminal particles at accelerators or to find them
in experiments devoted to high-energy cosmic rays. Similarly, the stringent
experimental bounds on Lorentz symmetry violation at low energy cannot be
extrapolated to high-energy phenomena. Several basic questions related to
possible effects of Lorentz symmetry violation are discussed, and potential
signatures are examined.


title: Exact Solution of selfconsistent Vlasov equation

abstract:
  An analytical solution of the selfconsistent Vlasov equation is presented.
The time evolution is entirely determined by the initial distribution function.
The largest Lyapunov exponent is calculated analytically. For special
parameters of the model potential positive Lyapunov exponent is possible. This
model may serve as a check for numerical codes solving selfconsistent Vlasov
equations. The here presented method is also applicable for any system with
analytical solution of the Hamilton equation for the formfactor of the
potential.

categories: physics.plasm-ph cond-mat.stat-mech math-ph math.MP nlin.SI nucl-th physics.comp-ph solv-int


title: Explicit bracket in the exceptional simple Lie superalgebra cvect(0|3)_*

abstract:
  This note is devoted to a more detailed description of one of the five simple
exceptional Lie superalgebras of vector fields, cvect(0|3)_*, a subalgebra of
vect(4|3). We derive differential equations for its elements, and solve these
equations. Hence we get an exact form for the elements of cvect(0|3)_*.
Moreover we realize cvect(0|3)_* by "glued" pairs of generating functions on a
(3|3)-dimensional periplectic (odd symplectic) supermanifold and describe the
bracket explicitly.


title: Einstein's Violation of General Covariance

abstract:
  Einstein rejected the differential law of energy-momentum conservation $
T^{\mu\nu}_{;\nu} = 0 $. In doing so, he violated the principle of general
covariance. Here, we prove the conservation law $ T^{\mu\nu}_{;\nu} = 0 $ and
discuss its significance for general relativity.


title: K-system generator of pseudorandom numbers on Galois field

abstract:
  We analyze the structure of the periodic trajectories of the K-system
generator of pseudorandom numbers on rational sublattice which coincides with
the Galois field. The period of the trajectories increases as a function of
lattice size and the dimension of the K-matrix. We emphasize the connection of
this approach with the one which is based on primitive matrices over Galois
fields.


title: A Baryonic Correction to General Relativity

abstract:
  The baryon overdensity and the matching of the big bang explosion energy with
gravitation can be solved by a cyclical baryonic bounce model with correction
to the stress-energy tensor. Subtracting accretion energy from the CMBR allows
enough baryons in nucleosynthesis to close the universe. Collapse to infinite
density states must be prevented by energy losses at supranuclear densities. As
long as the Einstein tensor is coupled to the stress-energy tensor, any quantum
correction must involve an energy sink.


title: A comparison of two operational wave assimilation methods

abstract:
  A comparison is carried out between two operational wave
forecasting/assimilation models for the North Sea, with the emphasis on the
assimilation schemes. One model is the WAM model, in combination with an
optimal interpolation method (OIP). The other model, DASWAM, consists of the
third generation wave model PHIDIAS in combination with an approximate
implementation of the adjoint method.
  In an experiment over the period February 19 - March 30, 1993, the models are
driven by the same wind field (HIRLAM analysis winds), and the same observation
data set is assimilated. This set consists of a) spectra from three
pitch-and-roll buoys and b) Synthetic Aperture Radar (SAR) spectra from the
ERS-1 satellite. Three analysis/forecast runs are performed: one without
assimilation, one with assimilation of buoy measurements only, and one with all
data assimilated. For validation, observations from four buoys, altimeter data
from ERS-1 and Topex-Poseidon, and scatterometer data from ERS-1 are used.
  A detailed analysis of the "Wadden Storm" (February 20-22) shows the very
different nature of the two assimilation schemes: the wave and wind field
corrections of the WAM/OIP scheme are all in the vicinity of the observations,
whereas the DASWAM adjustments are more of a global nature. The impact of some
individual buoy and SAR observations is visualized. A comparison of the
performance of the two schemes is somewhat obscured by the very different
behaviour of the two first-guess runs.
  A statistical analysis over the whole 39-day period gives the following
results. In a comparison with buoy observations it is shown that a positive
impact of wave data assimilation remains until about 12 hours in forecast in


title: Output coupling for an atom laser by state change

abstract:
  We calculate the spectrum of a beam of atoms output from a single mode atomic
cavity. The output coupling uses an internal state change to an untrapped
state. We present an analytical solution for the output energy spectrum from a
broadband coupler of this type. An example of such an output coupler, which we
discuss in detail uses a Raman transition to produce a non-trapped state.


title: On the way to understanding the electromagnetic phenomena

abstract:
  On the basis of the ordinary mathematical methods we discuss new classes of
solutions of the Maxwell's equations discovered in the papers by D. Ahluwalia,
M. Evans and H. M'unera et al.

categories: physics.gen-ph math-ph math.MP physics.class-ph


title:
An Approach to Maxwell Equations in Uniformly Accelerated Spherical
  Coordinates by Newman-Penrose Method

abstract:
  Variables are separated in Maxwell equations by the Newman-Penrose method of
isotropic complex tetrade in the uniformly accelerated spherical coordinate
system. Particular solutions are obtained in terms of spin 1 spherical
harmonics. PACS: 03.50.De


title: Integrating a general algebra

abstract:
  The problem of quantizing theories defined over configuration spaces
described by non-commuting parameters is considered. In this paper we describe
the first step in this direction, that is the definition of an integral over a
general algebra.


title:
Theorem on the proportionality of inertial and gravitational masses in
  classical mechanics

abstract:
  We considered the problem of the proportionality of inertial and
gravitational masses in classical mechanics. We found that the kinetic energy
of a material mass point m in a circular motion with a constant angular
velocity around another material point M depends only on its gravitational
mass. This fact, together with the known result that the straight line is a
circumference with an infinite radius, allowed us to prove the proportionality
between the inertial and gravitational masses.


title: Jones-matrix Formalism as a Representation of the Lorentz Group

abstract:
  It is shown that the two-by-two Jones-matrix formalism for polarization
optics is a six-parameter two-by-two representation of the Lorentz group. The
attenuation and phase-shift filters are represented respectively by the
three-parameter rotation subgroup and the three-parameter Lorentz group for two
spatial and one time dimensions. It is noted that the Lorentz group has another
three-parameter subgroup which is like the two-dimensional Euclidean group.
Possible optical filters having this Euclidean symmetry are discussed in
detail. It is shown also that the Jones-matrix formalism can be extended to
some of the non-orthogonal polarization coordinate systems within the framework
of the Lorentz-group representation.


title: Hypercomplex Group Theory

abstract:
  Due to the noncommutative nature of quaternions and octonions we introduce
barred operators. This objects give the opportunity to manipulate appropriately
the hypercomplex fields. The standard problems arising in the definitions of
transpose, determinant and trace for quaternionic and octonionic matrices are
immediately overcome. We also investigate the possibility to formulate a new
approach to Hypercomplex Group Theory (HGT). From a mathematical viewpoint, our
aim is to highlight the possibility of looking at new hypercomplex groups by
the use of barred operators as fundamental step toward a clear and complete
discussion of HGT.


title: Remarks on Some Applications of Skorokhod Space in Quantum Mechanics

abstract:
  This paper discusses the role of the Skorokhod space and the convergence of
probability measures on it in some recent studies of the foundations of quantum
mechanics, both in the conventional setting over the real number field and in
the more speculative one of nonarchimedean local fields.


title: Book Review: The Quantum Theory of Fields, Vol. I and II by S. Weinberg

abstract:
  Review of the two volume set "The Quantum Theory of Fields" by S. Weinberg is
presented.


title: Two-body effects in the decay rate of atomic levels

abstract:
  Recoil corrections to the atomic decay rate are considered in the order of
Zm/M . The expressions are treated exactly without any expansion over Z alpha.
The expressions obtained are valid both for muonic atoms (for which they
contribute on the level of a few percent in high Z ions) and for electronic
atoms. Explicit results for Lyman-alpha transitions for low-Z of the order
(Zm/M)(Z alpha)^2 are also presented.


title:
The size-extensitivity of correlation energy estimators based on
  effective characteristic polynomials

abstract:
  Estimators $\Pi n$ for the correlation energy can be computed as roots of
effective characteristic polynomials of degree $n$. The coefficients of these
polynomials are derived from the terms of the perturbation series of the
energy. From a fourth-order M{\o}ller-Plesset (MP4) calculation one can
calculate with negligible effort a size-extensive estimator $\Pi 2$ that is in
many cases much closer to the full CI correlation energy of the ground state
than the MP4 value. [H.H.H. Homeier, J. Mol. Struct. (Theochem) 366, 161
(1996)] Here, we prove that the estimators $\Pi n$ for $n>2$ are size-extensive
if they are calculated from the MP series.

categories: physics.chem-ph math-ph math.MP math.NA physics.comp-ph


title: Power Switching in Hybrid Coherent Couplers

abstract:
  We report on a theoretical and numerical investigation of the switching of
power in new hybrid models of nonlinear coherent couplers consisting of optical
slab waveguides with various orders of nonlinearity. The first model consists
of two guides with second-order instead of the usual third-order
susceptibilities as typified by the Jensen coupler. This second-order system is
shown to have a power self-trapping transition at a critical power greater than
the third-order susceptibility coupler. Next, we consider a mixed coupler
composed of a second-order guide coupled to a third-order guide and show that,
although it does not display a rigorous self-trapping transition, for a
particular choice of parameters it does show a fairly abrupt trapping of power
at a lower power than in the third-order coupler. By coupling this mixed
nonlinear pair to a third, purely linear guide, the power trapping can be
brought to even lower levels and in this way a satisfactory switching profile
can be achieved at less than one sixth the input power needed in the Jensen
coupler.


title: Ideal Gas in a Finite Container

abstract:
  The thermodynamics of an ideal gas enclosed in a box of volume a1 x a2 x a3
at temperature T is considered. The canonical partition function of the system
is expressed in terms of complete elliptic integrals of the first kind, whose
argument obeys a transcendental equation. For high and low temperatures we
derive explicitly the main finite-volume corrections to the standard
thermodynamic quantities.


title: Relativistic P\"oschl-Teller and Rosen-Morse problems

abstract:
  It is shown that the new family of geometric models of the relativistic
oscillator, which generalize the anti-de Sitter model, leads to relativistic
P\"oschl-Teller or Rosen-Morse problems.


title: Geometric Models of the Quantum Relativistic Rotating Oscillator

abstract:
  A family of geometric models of quantum relativistic rotating oscillator is
defined by using a set of one-parameter deformations of the static (3+1) de
Sitter or anti-de Sitter metrics. It is shown that all these models lead to the
usual isotropic harmonic oscillator in the non-relativistic limit, even though
their relativistic behavior is different. As in the case of the (1+1) models,
these will have even countable energy spectra or mixed ones, with a finite
discrete sequence and a continuous part. In addition, all these spectra, except
that of the pure anti-de Sitter model, will have a fine-structure, given by a
rotator-like term.


title: Geometric Models of the Relativistic Harmonic Oscillator

abstract:
  A family of relativistic geometric models is defined as a generalization of
the actual anti-de Sitter (1+1) model of the relativistic harmonic oscillator.
It is shown that all these models lead to the usual harmonic oscillator in the
non-relativistic limit, even though their relativistic behavior is quite
different. Among quantum models we find a set of models with countable energy
spectra, and another one having only a finite number of energy levels and in
addition a continuous spectrum.


title:
Current-Voltage Characteristic of a Partially Ionized Plasma in
  Cylindrical Geometry

abstract:
  The properties of a partially ionized plasma in a long cylindrical tube
subject to a uniform axial electric field are investigated. The plasma is
maintained by an external ionizing source balanced by bulk and surface
recombinations. Collisions between neutrals, whose density greatly exceeds the
density of charged particles, and of neutrals with ions are sufficiently
effective for their velocity distribution to be close to a Maxwellian with the
same uniform temperature, independent of the external field. The behavior of
the plasma is described by a collisional two-fluid scheme with charge
neutrality in the interior of the tube. Approximate nonlinear equations for the
hydrodynamical moments are obtained from a Boltzmann equation in which
electron-neutral, electron-ion and electron-electron collisions are all
important. It is found that under certain circumstances the current, and the
temperature of the electrons undergo a drastic change, with hysteresis, as the
electric field is varied.


title: Simulating Plasma Turbulence in Tokamaks

abstract:
  A challenging and fundamental research problem is the better understanding
and control of the turbulent transport of heat in present-day tokamak fusion
experiments. Recent developments in numerical methods along with enormous gains
in computing power have made large-scale simulations an important tool for
improving our understanding of this phenomena. Simulating this highly
non-linear behavior requires solving for the perturbations of the phase space
distribution function in five dimensions. We use a particle-in-cell approach to
solve the equations. The code has been parallelized for a variety of
architectures (C90, CM-5, T3D) using a 1-D domain decomposition along the
toroidal axis, for which the number of particles in each cell remains
approximately constant. The quasi-uniform distribution of particles, which
minimizes load imbalance, coupled with the relatively small movement of
particles across cells, which minimizes communications, makes this problem
ideally suited to massively parallel architectures. We present the performance
of the program for different numbers of processors and problem sizes. In
addition, we discuss some recent scientific results obtained from the code.


title: Simulations of the Interaction Region in a Photon-Photon Collider

abstract:
  The status and initial performance of a simulation program CAIN for
interaction region of linear colliders is described. The program is developed
to be applicable for e+e-, e-e-, e-gamma and gamma-gamma linear colliders. As
an example of an application, simulation of a gamma-gamma collider option of
NLC is reported.


title:
Detection of Minimum-Ionizing Particles and Nuclear Counter Effect with
  Pure BGO and BSO Crystals with Photodiode Read-out

abstract:
  Long BGO (Bismuth Germanate) and BSO (Bismuth Silicate) crystals coupled with
silicon photodiodes have been used to detect minimum-ionizing particles(MIP).
With a low noise amplifier customized for this purpose, the crystals can detect
MIPs with an excellent signal-to-noise ratio. The NCE(Nuclear Counter Effect}
is also clearly observed and measured. Effect of full and partial wrapping of a
reflector around the crystal on light collection is also studied.


title:
Conceivable new recycling of nuclear waste by nuclear power companies in
  their plants

abstract:
  We outline the basic principles and the needed experiments for a conceivable
new recycling of nuclear waste by the power plants themselves to avoid its
transportation and storage to a (yet unknown) dumping area. Details are
provided in an adjoining paper and in patents pending.


title:
Use of relativistic hadronic mechanics for the exact representation of
  nuclear magnetic moments and the prediction of new recycling of nuclear waste

abstract:
  We present a new realization of relativistic hadronic me- chanics and its
underlying iso-Poincar'e symmetry specifically constructed for nuclear physics
which: 1) permits the representation of nucleons as ex- tended, nonspherical
and deformable charge distributions with alterable mag- netic moments yet
conventional angular momentum and spin; 2) results to be a nonunitary
``completion'' of relativistic quantum mechanics much along the EPR argument;
yet 3) is axiom-preserving, thus preserves conventional quantum laws and the
axioms of the special relativity. We show that the proposed new formalism
permits the apparently first exact representation of the total magnetic moments
of new-body nuclei under conventional physical laws. We then point out that, if
experimentally confirmed the alterability of the intrinsic characteristics of
nucleons would imply new forms of recycling nuclear waste by the nuclear power
plants in their own site, thus avoiding its transportation and storage in a
(yet unidentified) dumping area. A number of possible, additional basic
advances are also indicated, such as: new un- derstanding of nuclear forces
with nowel nonlinear, nonlocal and nonunitary terms due to mutual penetrations
of the hyperdense nucleons; consequential new models of nuclear structures; new
magnetic confinement of the controlled fusion taking into account the possible
alterability of the intrinsic magnetic moments of nucleons at the initiation of
the fusion process; new sources of en- ergy based on subnuclear processes; and
other possible advances. The paper ends with the proposal of three experiments,
all essential for the continuation of scientific studies and all of basic
character, relatively moderate cost and full feasibility in any nuclear
physical laboratory.


title: Post-Collision Interaction with Wannier electrons

abstract:
  A theory of the Post-Collision Interaction (PCI) is developed for the case
when an electron atom impact results in creation of two low-energy Wannier
electrons and an ion excited into an autoionizing state. The following
autoionization decay exposes the Wannier pair to the influence of PCI resulting
in variation of the shape of the line in the autoionization spectrum. An
explicit dependence of the autoionization profile on the wave function of the
Wannier pair is found. PCI provides an opportunity to study this wave function
for a wide area of distances


title: Vacuum Structure, Lorentz Symmetry and Superluminal Particles

abstract:
  If textbook Lorentz invariance is actually a property of the equations
describing a sector of the excitations of vacuum above some critical distance
scale, several sectors of matter with different critical speeds in vacuum can
coexist and an absolute rest frame (the vacuum rest frame) may exist without
contradicting the apparent Lorentz invariance felt by "ordinary" particles
(particles with critical speed in vacuum equal to $c$ , the speed of light).
The sectorial Lorentz symmetry may be only a low-energy limit, in the same way
as the relation $\omega $ (frequency) = $c_s$ (speed of sound) $k$ (wave
vector) holds for low-energy phonons in a crystal. We study the consequences of
such a scenario, using an ansatz inspired by the Bravais lattice as a model for
some vacuum properties. It then turns out that: a) the Greisen-Zatsepin-Kuzmin
cutoff on high-energy cosmic protons and nuclei does no longer apply; b)
high-momentum unstable particles have longer lifetimes than expected with exact
Lorentz invariance, and may even become stable at the highest observed cosmic
ray energies or slightly above. Some cosmological implications of superluminal
particles are also discussed.


title: Some minimally-variant map-based rules of motion at any speed

abstract:
  We take J. S. Bell's commendation of ``frame-dependent'' perspectives to the
limit here, and consider motion on a ``map'' of landmarks and clocks fixed with
respect to a single arbitrary inertial-reference frame. The metric equation
connects a traveler-time with map-times, yielding simple integrals of constant
proper-acceleration over space (energy), traveler-time (felt impulse), map-time
(momentum), and time on the clocks of a chase-plane determined to see Galileo's
original equations apply at high speed. Rules follow for applying frame-variant
and proper forces in context of one frame. Their usefulness in curved
spacetimes via the equivalence principle is maximized by using synchrony-free
and/or frame-invariant forms for length, time, velocity, and acceleration. In
context of any single system of locally inertial frames, the metric equation
thus lets us express electric and magnetic effects with a single
frame-invariant but velocity-dependent force, and to contrast such forces with
gravity as well.


title:
Closed-form solutions of the Schroedinger equation for a class of
  smoothed Coulomb potentials

abstract:
  An infinite family of closed-form solutions is exhibited for the Schroedinger
equation for the potential $V(r) = -Z/\sqrt{|r|^{2} + a^{2}}$. Evidence is
presented for an approximate dynamical symmetry for large values of the angular
momentum $l$.


title:
Electrostatic potentials and free energies of solvation of polar and
  charged molecules

abstract:
  Theories of solvation free energies often involve electrostatic potentials at
the position of a solute charge. Simulation calculations that apply cutoffs and
periodic boundary conditions based on molecular centers result in
center-dependent contributions to electrostatic energies due to a systematic
sorting of charges in radial shells. This sorting of charges induces a
surface-charge density at the cutoff sphere or simulation-box boundary that
depends on the choice of molecular centers. We identify a simple solution that
gives correct, center-independent results, namely the radial integration of
charge densities. Our conclusions are illustrated for a Lennard-Jones solute in
water. The present results can affect the parameterization of force fields.


title:
Low-Background Experiments with High Pressure Gas Scintillation
  Proportional Detector

abstract:
  A scintillation proportional counter with wavelength shifting fiber readout
filled with Xe or Kr under a pressure of up to 20 atm is proposed for the
low-background experiments on search for dark matter of the Universe and
2K-decay of 78 Kr.


title:
A Simple Model for Predicting Sprint Race Times Accounting for Energy
  Loss on the Curve

abstract:
  The mathematical model of J. Keller for predicting World Record race times,
based on a simple differential equation of motion, predicted quite well the
records of the day. One of its shortcoming is that it neglects to account for a
sprinter's energy loss around a curve, a most important consideration
particularly in the 200m--400m. An extension to Keller's work is considered,
modeling the aforementioned energy loss as a simple function of the centrifugal
force acting on the runner around the curve. Theoretical World Record
performances for indoor and outdoor 200m are discussed, and the use of the
model at 300m is investigated. Some predictions are made for possible 200m
outdoor and indoor times as run by Canadian 100m WR holder Donovan Bailey,
based on his 100m final performance at the 1996 Olympic Games in Atlanta.


title: And the Winner Is . . . Predicting the Outcome of the 150m Showdown

abstract:
  Using the model framework for curve running as described in physics/9704022,
the possible outcome of the 150m "One to One" showdown between sprinters
Donovan Bailey and Michael Johnson are discussed (to be run 01 Jun 1997 at
Skydome in Toronto, Ontario, Canada).


title:
Studies on Santilli's Locally Anisotropic and Inhomogeneous
  Isogeometries: I. Isobundles and Generalized Isofinsler Gravity

abstract:
  We generalize the geometry of Santilli's locally anisotropic and
inhomogeneous isospaces to the geometry of vector isobundles provided with
nonlinear and distinguished isoconnections and isometric structures. We
present, apparently for the first time, the isotopies of Lagrange, Finsler and
Kaluza--Klein spaces. We also continue the study of the interior, locally
anisotropic and inhomogeneous gravitation by extending the isoriemannian
space's constructions and presenting a geometric background for the theory of
isofield interactions in generalized isolagrange and isofinsler spaces.


title: Green's matrix from Jacobi-matrix Hamiltonian

abstract:
  We propose two ways for determining the Green's matrix for problems admitting
Hamiltonians that have infinite symmetric tridiagonal (i.e. Jacobi) matrix form
on some basis representation. In addition to the recurrence relation comming
from the Jacobi-matrix, the first approach also requires the matrix elements of
the Green's operator between the first elements of the basis. In the second
approach the recurrence relation is solved directly by continued fractions and
the solution is continued analytically to the whole complex plane. Both
approaches are illustrated with the non-trivial but calculable example of the
D-dimensional Coulomb Green's matrix. We give the corresponding formulas for
the D-dimensional harmonic oscillator as well.


title:
Approximate Analytic Solution for the Spatiotemporal Evolution of Wave
  Packets undergoing Arbitrary Dispersion

abstract:
  We apply expansion methods to obtain an approximate expression in terms of
elementary functions for the space and time dependence of wave packets in a
dispersive medium. The specific application to pulses in a cold plasma is
considered in detail, and the explicit analytic formula that results is
provided. When certain general initial conditions are satisfied, these
expressions describe the packet evolution quite well. We conclude by employing
the method to exhibit aspects of dispersive pulse propagation in a cold plasma,
and suggest how predicted and experimental effects may be compared to improve
the theoretical description of a medium's dispersive properties.


title:
Transition to the Most Probable Kinetic State in a Pre-Steady State
  System

abstract:
  A system containing a pre-steady state standard (non-autocatalytic) reaction,
with multiple paths, evolves toward a kinetic state with the minimum attainable
activation free energy. Displacement of the path frequency distribution in this
transition was shown to minimise the affinity linked to this change in
activation free energy. In damping this scalar force, a standard system is
driven along a path of least action, as previously established for a system of
competing autocatalytic reactions. A kinetic source of time asymmetry arises
within the system, as the activation affinity moves the system toward the most
probable distribution of reaction paths. As the functions of state are not
changed by path displacement, a change of kinetic state cannot produce chemical
work. This generalises the notion of force to a scalar quantity responsible for
a displacement that does not yield work or heat. Spectrophotometric
observations reported on the transition to steady state kinetics during
dinitrophenyl phosphate phosphorolysis confirmed that time variations in the
activation affinity are non-positive.


title: The third way to quantum mechanics is the forgotten first

abstract:
  Quantum mechanics can be formulated in three ways, as Heisenberg,
Schr\"odinger and Feynman did respectively. For the last way, an unknown (i.e.
forgotten) forerunner exists, that we have found in a paper by Gregor Wentzel,
published before the famous works by Heisenberg and Schr\"odinger, and
contemporary with the fundamental works of L. de Broglie. In that paper, one
can find the basic formulae and their interpretation as they were adopted by
Feynman twenty years later. We believe that Wentzel's work was forgotten for
several reasons: (I) Schr\"odinger's equation was much simpler to deal with
(Wentzel himself contributed to its development in the same way as L.Brillouin
and H.Kramers did). (II) The first application was rejected by Heisenberg and
Kramers. (III) The approximation used by Wentzel was too na\"\i ve and failed.
Nevertheless, the foundation laid by Wentzel was sound, as it has been shown by
Feynman's work. Therefore, Wentzel has to be considered as one of the founders
of quantum mechanics.


title: Are the Bader Laplacian and the Bohm Quantum Potential Equivalent?

abstract:
  The de Broglie-Bohm ontological interpretation of quantum theory clarifies
the understanding of many otherwise counter-intuitive quantum mechanical
phenomena. We report here on an application of Bohm's quantum potential to the
bonding and reactivity of small molecules.
  In the field of quantum chemistry, Bader has shown that the topology of the
Laplacian of the electronic charge density characterizes many features of
molecular structure and reactivity. Examination of high accuracy ab-initio
solutions for several small molecules suggests that the Laplacian of Bader and
the quantum potential of Bohm are structurally equivalent. It is possible that
Bohmian mechanics using the quantum potential can make quantum chemistry as
clear as it makes non-relativistic quantum mechanics.


title: Classical isodual theory of antimatter

abstract:
  An inspection of the contemporary physics literature reveals that, while
matter is treated at all levels of study, from Newtonian mechanics to quantum
field theory, antimatter is solely treated at the level of second quantization.
For the purpose of initiating the restoration of full equivalence in the
treatments of matter and antimatter in due time, in this paper we present a
classical representation of antimatter which begins at the primitive Newtonian
level with expected images at all subsequent levels. By recalling that charge
conjugation of particles into antiparticles is anti-automorphic, the proposed
theory of antimatter is based on a new map, called isoduality, which is also
anti-automorphic, yet it is applicable beginning at the classical level and
then persists at the quantum level. As part of our study, we present novel
anti-isomorphic isodual images of the Galilean, special and general
relativities and show the compatibility of their representation of antimatter
with all available classical experimental knowledge, that on electromagnetic
interactions. We also identify the prediction of antigravity for antimatter in
the field of matter (or vice-versa) without any claim on its validity, and
defer its resolution to specific experiments. To avoid a prohibitive length,
the paper is restricted to the classical treatment which had not been
sufficiently treated until now. Studies on operator profiles, such as the
equivalence of isoduality and charge conjugation and the implication of the
isodual theory in particle physics, are conducted in a separate paper.


title: A computational study of 13-atom Ne-Ar cluster heat capacities

abstract:
  Heat capacity curves as functions of temperature were calculated using Monte
Carlo methods for the series of Ne_(13-n)Ar_n clusters (0 <= n <= 13). The
clusters were modeled classically using pairwise additive Lennard-Jones
potentials. The J-walking (or jump-walking) method was used to overcome
systematic errors due to quasiergodicity. Substantial discrepancies between the
J-walking results and those obtained using standard Metropolis methods were
found. Results obtained using the atom-exchange method, another Monte Carlo
variant for multi-component systems, also did not compare well with the
J-walker results. Quench studies were done to investigate the clusters'
potential energy surfaces. Only those Ne-Ar clusters consisting predominately
of either one or the other component had lowest energy isomers having the
icosahedral-like symmetry typical of homogeneous 13-atom rare gas clusters;
non-icosahedral structures dominated the lowest-energy isomers for the other
clusters. This resulted in heat capacity curves that were very much different
than that of their homogeneous counterpart. Evidence for coexistence behavior
different than that seen in homogenous clusters is also presented.


title: A Elasticidade Relativista

abstract:
  The purpose of this paper is to make clear the difference between rigid and
undeformable bodies in Relativity. The error of confusing these two concepts
has survived up to the present day treatises. We hope it will not persist in
the XXI century treatises. The large majority of relativists do not know the
formulae for the relativistic elasticity of rigid bodies (Mc Crea 1952,Brotas
1968). The paradoxes of the rotating disk and of the 3-degrees of freedom of
rigidies bodies in Relativity are in the domain of relativistic elasticity.


title: What really are the best 100m performances?

abstract:
  A quick and fun investigation into the effects of correcting for wind
assistance/resistance and drag on 100m sprint performances. Considered are
World 100m rankings, as well as Canadian rankings


title:
Evolution and global collapse of trapped Bose condensates under
  variations of the scattering length

abstract:
  We develop the idea of selectively manipulating the condensate in a trapped
Bose-condensed gas, without perturbing the thermal cloud. The idea is based on
the possibility to modify the mean field interaction between atoms (scattering
length) by nearly resonant incident light or by spatially uniform change of the
trapping magnetic field. For the gas in the Thomas-Fermi regime we find
analytical scaling solutions for the condensate wavefunction evolving under
arbitrary variations of the scattering length $a$. The change of $a$ from
positive to negative induces a global collapse of the condensate, and the final
stages of the collapse will be governed by intrinsic decay processes.


title: Low-energy elementary excitations of a trapped Bose-condensed gas

abstract:
  Bogolyubov-De Gennes equations for the excitations of a Bose condensate in
the Thomas-Fermi regime in harmonic traps of any asymmetry and introduce a
classification of eigenstates. In the case of cylindrical symmetry we emphasize
the presence of an accidental degeneracy in the excitation spectrum at certain
values of the projection of orbital angular momentum on the symmetry axis and
discuss possible consequences of the degeneracy in the context of new
signatures of Bose-Einstein condensation.


title:
Superconductivity, the Structure Scale of the Universe, Tenth Edition
  (Elastic Resonant Symmetric Medium by Self-Energy)

abstract:
  A theoretical framework supported by literature reported experimental
evidence (Homes, Harshman along with Voyager, Hubble and EGRET space platforms
and others) is presented which indicates that superconductivity is a self
energy phenomenon and congruent with the concept of the Charge Conjugation,
Parity Change and Time Reversal (CPT) theorem. A resonant symmetric structure
is proposed as an extension of Bardeen Cooper and Schrieffer (BCS) theory,
which suspends Lorentz transforms at superluminal velocities in the context of
the de Broglie hypothesis. A momentum and energy conserving (elastic) CPT
resonant structural lattice scalable over 15 orders of magnitude from nuclear
to universe dimensions and associated superconducting theory is postulated
whereby nuclear (quark) weak and strong forces, electromagnetic and
gravitational forces are mediated by a particle of resonant velocity
transformed mass (mt) (110.123 x electron mass or 56 Mev/c2), The universe mass
and density are based on an isotropic homogeneous media filling the vacuum of
and could be considered a candidate for dark matter/energy. The model predicts
a deceleration value consistent with observed Pioneer 10 and 11 deep space
translational and rotational deceleration and consistent with the notion that,
An object moving through momentum space will slow down.


title: A Simple Model of Evolution with Variable System Size

abstract:
  A simple model of biological extinction with variable system size is
presented that exhibits a power-law distribution of extinction event sizes. The
model is a generalization of a model recently introduced by Newman (Proc. R.
Soc. Lond. B265, 1605 (1996). Both analytical and numerical analysis show that
the exponent of the power-law distribution depends only marginally on the
growth rate $g$ at which new species enter the system and is equal to the one
of the original model in the limit $g\to\infty$. A critical growth rate $g_c$
can be found below which the system dies out. Under these model assumptions
stable ecosystems can only exist if the regrowth of species is sufficiently
fast.

categories: physics.bio-ph adap-org cond-mat.dis-nn nlin.AO physics.data-an q-bio


title: Finite-temperature evaluation of the Fermi density operator

abstract:
  A rational expansion of the Fermi density operator is proposed. This approach
allows to calculate efficiently physical properties of fermionic systems at
finite temperatures without solving an eigenvalue problem. Using N evaluations
of the Green's function, the Fermi density operator can be approximated,
subject to a given precision, in the energy interval from -A to infinity with A
proportional to N. The presented method may become especially useful for
electronic structure calculations involving the calculation of charge
densities.


title:
Stark quenching for the $1s^22s2p^3P_0$ level in beryllium-like ions and
  parity-violating effects

abstract:
  In this paper we present some concepts in heavy ion atomic physics for the
extraction of parity violating effects. We investigate the effects of the
so-called Stark-quenching, i.e., the fast decay of a meta stable state induced
by a Stark field, and the superposition of one- and two-photon transitions in
beryllium-like heavy ions. It turns out that the discussed theoretical
phenomena for heavy ions with few electrons are beyond the scope of present day
experimental possibilities because one has to require beam energies of up to 1
TeV/A, laser intensities of up to $10^{17} {\rm W/cm^2}$ and ion currents of up
to $10^{11}$ ions per second in beryllium-like uranium. However, especially the
superposition of one- and two-photon transitions is a very interesting
phenomenon that could provide the germ of an idea to be applied in a more
favorable system.


title: The Supersymmetry of Relativistic Poschl-Teller Systems

abstract:
  We analyze the supersymmetry and the shape invariance of the potentials of
the (1+1) relativistic oscillators we have recently proposed.


title: The Operator Algebra of the Quantum Relativistic Oscillator

abstract:
  The operator algebras of a new family of relativistic geometric models of the
relativistic oscillator are studied. It is shown that, generally, the operator
of number of quanta and the pair of the shift operators of each model are the
generators of a non-unitary representation of the $so(1,2)$ algebra, except a
special case when this algebra becomes the standard one of the non-relativistic
harmonic oscillator.


title: Global boundary conditions for the Dirac operator

abstract:
  Ellipticity of boundary value problems is characterized in terms of the
Calderon projector. The presence of topological obstructions for the chiral
Dirac operator under local boundary conditions in even dimension is discussed.
Functional determinants for Dirac operators on manifolds with boundary are
considered.
  The functional determinant for a Dirac operator on a bidimensional disk, in
the presence of an Abelian gauge field and subject to global boundary
conditions of the type introduced by Atiyah-Patodi-Singer, is evaluated. The
relationship with the index theorem is also commented.


title: Restoration of the Past and Three Principles of Time

abstract:
  Can the Past be restored? Poincar\'e and Costa de Beauregard showed that the
past is not restored statistically. This follows from Bayes formula. In given
note two new Principles are postulated which forbid the restoration of the
Past.


title:
Isominkowskian unification of the special and general relativities
  (letter)

abstract:
  We submit a classical unification of the special and general relativities via
the new isominkowskian geometry in which the two relativities are
differentiated by the basic unit. We then show that the unification admits an
operator image in which gravitation verifies the abstract axioms of
relativistic quantum mechanics under a universal symmetry which is isomorphic
to the Poincar\'{e} symmetry. The compliance of the unification with available
experimental data is indicated. This study has been permitted by the recent
achievement of sufficient mathematical maturity in memoir$^{3f}$, axiomatic
consistency in memoir$^{3t}$ and generalized symmetry principles in
memoir$^{4v}$. More detailed studies are presented in the forthcoming
paper$^{3u}$.


title:
Classical and operator isominkowskian unification of general and special
  relativities for metter and their isodual for antimatter (paper)

abstract:
  We recall that the Minkowskian geometry possesses basic units of space and
time which are invariant under the Poincar\'{e} symmetry. We then show that, by
comparison, the Riemannian geometry possesses space-time units which are not
invariant under the symmetries of the Riemannian line element, thus causing
evident physical ambiguities. We therefore introduce a novel formulation of
general relativity in the isominkowskian geometry which is an axiom-preserving
lifting of the conventional Minkowskian geometry but which nevertheless admits
all possible Riemannian metrics thanks to a (positive-definite) $4 \times 4$
generalization of the basic unit. We construct the universal symmetry of the
isominkowskian line elements called isopoincar\'{e} symmetry}, prove that it is
locally isomorphic to the conventional Poincar\'{e} symmetry, and show that, in
this way, conventional Riemannian metrics and related field equations can be
expressed with respect to invariant generalized units of space and time. We
then show that the isominkowskian geometry and related isopoincar\'{e} symmetry
permit: I) A classical geometric unification of the general and special
relativities for matter into a formulation called isospecial relativity in
which the former occurs for generalized units while admitting the latter as a
particular case for conventional units; II) A novel operator formulation of
gravity for matter based on the abstract axioms of relativistic quantum
mechanics, thus showing hope for a possible resolution of the ambiguities in
current theories of quantum gravity; and III) A novel classical and operator
formulation of antimatter which is an antiautomorphic image of the preceding
formulations for matter constructed via a map called isoduality. The


title:
The distorted-wave impulse approximation for electron capture into
  excited states

abstract:
  Total cross sections for electron capture are calculated for collisions of
fast protons and alpha-particles with atomic hydrogen. The distorted- wave
impulse approximation is applied over the energy range 10-1500 keV/u.
State-selective results are given for the 1s, 2s and 2p levels. Both the 'post'
and 'prior' forms of the model are calculated and compared with results from
other theories and experimental measurements. In general the model performs
very well in comparison with experiment over this energy range though
discrepancies arise at lower energies.


title: Invariant formulation of q-deformations via the novel genomathematics

abstract:
  In this note we outline the history of q-deformations; indicate their
physical shortcomings; suggest their apparent resolution via an invariant
formulation based on a new mathematics of genotopic type; and point out their
expected physical significance once formulated in an invariant way.


title:
Comments on the Hypothesis about Possible Class of Particles Able to
  Travel Faster then Light: Some Geometrical Models

abstract:
  The hypothesis about possible existence of new class of particles able to
travel faster then light as a source of dark matter, recently formulated by L.
Gonzalez-Mesters, is analyzed. To this end the general geometrical model for
several kinds of matter with different Lorentziann structures coexisting on the
same manifold is introduced and the local energy density in cosmological
reference frame is calculated in two particular cases. It is shown that the
local energy density is positive in both considered cases and hence such models
really may describe cosmological dark matter. Nevertheless, some problems may
appear during the construction of the cosmological models or the models of the
compact objects. Moreover, the simplest generalization of the model lead to
some variants of vector-tensor theory of gravitation with preferable reference
frame which contradict to observations.


title: Boundary-layer control by electric fields: A feasibility study

abstract:
  A problem of great concern in aviation and submarine propulsion is the
control of the boundary layer and, in particular, the methods to extend the
laminar region as a means to decrease noise and fuel consumption. In this paper
we study the flow of air along an airfoil when a layer of ionized gas and a
longitudinal electric field are created in the boundary layer region. By
deriving scaling solutions and more accurate numerical solutions we discuss the
possibility of achieving significant boundary layer control for realistic
physical parameters. Practical design formulas and criteria are obtained. We
also discuss the perspectives for active control of the laminar-to-turbulent
transition fluctuations by electromagnetic field modulation.


title:
Analytic Continuation of Bernoulli Numbers, a New Formula for the
  Riemann Zeta Function, and the Phenonmenon of Scattering of Zeros

abstract:
  The method analytic continuation of operators acting integer n-times to
complex s-times (hep-th/9707206) is applied to an operator that generates
Bernoulli numbers B_n (Math. Mag. 70(1), 51 (1997)). B_n and Bernoulli
polynomials B_n(s) are analytic continued to B(s) and B_s(z). A new formula for
the Riemann zeta function zeta(s) in terms of nested series of zeta(n) is
derived. The new concept of dynamics of the zeros of analytic continued
polynomials is introduced, and an interesting phenonmenon of `scatterings' of
the zeros of B_s(z) is observed.


title: Quasi-Exactly Solvable Time-Dependent Potentials

abstract:
  We find exact solutions of the time-dependent Schr\"odinger equation for a
family of quasi-exactly solvable time-dependent potentials by means of
non-unitary gauge transformations.

categories: math-ph math.MP nlin.SI quant-ph solv-int


title:
Artificial Neural Networks for Solving Ordinary and Partial Differential
  Equations

abstract:
  We present a method to solve initial and boundary value problems using
artificial neural networks. A trial solution of the differential equation is
written as a sum of two parts. The first part satisfies the boundary (or
initial) conditions and contains no adjustable parameters. The second part is
constructed so as not to affect the boundary conditions. This part involves a
feedforward neural network, containing adjustable parameters (the weights).
Hence by construction the boundary conditions are satisfied and the network is
trained to satisfy the differential equation. The applicability of this
approach ranges from single ODE's, to systems of coupled ODE's and also to
PDE's. In this article we illustrate the method by solving a variety of model
problems and present comparisons with finite elements for several cases of
partial differential equations.

categories: physics.comp-ph comp-gas nlin.CG quant-ph


title:
An instability criterion for a finite amplitude localized disturbance in
  a shear flow of electrically conducting fluids

abstract:
  The stability of shear flows of electrically conducting fluids, with respect
to finite amplitude three-dimensional localized disturbances is considered. The
time evolution of the fluid impulse integral, characterizing such disturbances,
for the case of low magnetic Reynolds number is obtained by integrating
analytically the vorticity equation. Analysis of the resulted equation reveals
a new instability criterion.


title: Renormalizing Recitation Grades

abstract:
  I discuss issue of how to adjust recitation grades given by different
instructors in a large course, taking into account and correcting for
differences in standards among the instructors, while preserving the effects of
differences in average student performance among the recitation sections.


title:
A soluble model of evolution and extinction dynamics in a rugged fitness
  landscape

abstract:
  We consider a continuum version of a previously introduced and numerically
studied model of macroevolution (PRL 75, 2055, (1995)) in which agents evolve
by an optimization process in a rugged fitness landscape and die due to their
competitive interactions. We first formulate dynamical equations for the
fitness distribution and the survival probability. Secondly we analytically
derive the $t^{-2}$ law which characterizes the life time distribution of
biological genera. Thirdly we discuss other dynamical properties of the model
such as the rate of extinction and conclude with a brief discussion.


title:
The split density model: a unified description of polarization and array
  dynamics for vertical cavity surface emitting lasers

abstract:
  A rate equation model describing the laser dynamics of general one or two
dimensional vertical cavity surface emitting laser (vcsel) arrays is
introduced. It is shown that the theory includes both the previous theory for
edge emitting semiconductor laser arrays and the theory of polarization
dynamics in single quantum well vcsels in a single unified description. The
model is based on the physical assumption of separate carrier density pools
individually coupled to different light field modes. These modes interact
through the coherent light field dynamics derived from Maxwell's equations. The
special case of two densities and two light field modes is solved and the
implications for larger arrays are discussed. Our analytic results show that
typical solutions of the split density model range from phase locking to chaos,
depending on the magnitude of the coherent interaction. For weak coupling the
stable supermode is always the mode of highest frequency. This indicates that
anti-phase locking is the only stable phase locking possible in semiconductor
laser arrays.

categories: physics.optics adap-org chao-dyn cond-mat nlin.AO nlin.CD


title: Stability and Halo Formation in Axisymmetric Intense Beams

abstract:
  Beam stability and halo formation in high-intensity axisymmetric 2D beams in
a uniform focusing channel are analyzed using particle-in-cell simulations. The
tune depression - mismatch space is explored for the uniform (KV) distribution
of the particle transverse-phase-space density, as well as for more realistic
ones (in particular, the water-bag distribution), to determine the stability
limits and halo parameters. The numerical results show an agreement with
predictions of the analytical model for halo formation (R.L. Gluckstern, Phys.
Rev. Letters, 73 (1994) 1247).


title:
Self-energy correction to the hyperfine structure splitting of the 1s
  and 2s states in hydrogenlike ions

abstract:
  The one-loop self-energy correction to the hyperfine structure splitting of
the 1s and 2s states of hydrogenlike ions is calculated both for the point and
finite nucleus. The results of the calculation are combined with other
corrections to find the ground state hyperfine splitting in lithiumlike
^{209}Bi^{80+} and ^{165}Ho^{64+}.


title:
Studies on Santilli's Locally Anisotropic and Inhomogeneous
  Isogeometries: I. Isobundles and Generalized Isofinsler Geometry

abstract:
  We generalize the geometry of Santilli's locally anisotropic and
inhomogeneous isospaces to the geometry of vector isobundles provided with
nonlinear and distinguished isoconnections and isometric structures. We
present, apparently for the first time, the isotopies of Lagrange, Finsler and
Kaluza-Klein spaces. We also continue the study of the interior, locally
anisotropic and inhomogeneous gravitation by extending the isoriemannian
space's constructions and presenting a geometric background for the theory of
isofield interactions in generalized isolagrange and isofinsler spaces.