title:
Absence of Greisen-Zatsepin-Kuzmin Cutoff and Stability of Unstable
  Particles at Very High Energy, as a Consequence of Lorentz Symmetry Violation

abstract:
  Special relativity has been tested at low energy with great accuracy, but its
extrapolation to very high-energy phenomena is much less well established.
Introducing a critical distance scale, a , below 10E-25 cm (the wavelength
scale of the highest-energy observed cosmic rays) allows to consider models,
compatible with standard tests of special relativity, where a small violation
of Lorentz symmetry (a can, for instance, be the Planck length) produces
dramatic effects on the properties of high-energy cosmic rays. Not only the
Greisen-Zatsepin-Kuzmin (GZK) cutoff on very high-energy protons and nuclei
does no longer apply, but particles which are unstable at low energy (neutron,
several nuclei, some hadronic resonances like the Delta++...) would become
stable at very high energy. The muon would also become stable or very long
lived at very high energy if one of the two neutrinos associated to the light
charged leptons (electron, muon) has a mass. Similar considerations apply to
the tau lepton. We discuss several possible scenarios originating these
phenomena, as well as the cosmic ray energy range (well below the energy scale
associated to the fundamental length) and experiments where they could be
detected. Observable effects are predicted for the highest-energy cosmic rays.


title: Superluminal Particles and High-Energy Cosmic Rays

abstract:
  Lorentz symmetry has been tested at low energy with great accuracy, but its
extrapolation to very high-energy phenomena is much less well established. We
expect a possible breaking of Lorentz symmetry to be a very high energy and
very short distance phenomenon, compatible with existing data. If textbook
special relativity is only an approximate property of the equations describing
a sector of matter above some critical distance scale, superluminal sectors of
matter may exist related to new degrees of freedom not yet discovered
experimentally. The new superluminal particles ("superbradyons") would have
positive mass and energy, and behave kinematically like "ordinary" particles
(those with critical speed in vacuum equal to c , the speed of light) apart
from the difference in critical speed (we expect c_i >> c , where c_i is the
critical speed of a superluminal sector of matter). At speed v > c , they are
expected to release "Cherenkov" radiation ("ordinary" particles) in vacuum. If
superluminal particles exist, they could provide most of the cosmic (dark)
matter and produce very high-energy cosmic rays compatible with unexplained
discoveries reported in the literature. We discuss: a) the possible relevance
of superluminal matter to the composition, sources and spectra of high-energy
cosmic rays; b) signatures and experiments allowing to possibly explore such
effects.


title: Why is topography fractal?

abstract:
  The power spectrum S of linear transects of the earth's topography is often
observed to be a power-law function of wave number k with exponent close to -2:
S(k) is proportional to k^-2. In addition, river networks are fractal trees
that satisfy many power-law or fractal relationships between their morphologic
components. A model equation for the evolution of the earth's topography by
erosional processes which produces fractal topography and fractal river
networks is presented and its solutions compared in detail to real topography.
The model is the diffusion equation for sediment transport on hillslopes and
channels with the local diffusivity proportional to the square of the
discharge. The dependence of diffusivity on discharge follows from fundamental
equations of sediment transport. We study the model in two ways. In the first
analysis the diffusivity is parameterized as a function of relief and a Taylor
expansion procedure is carried out to obtain a differential equation for the
landform elevation which includes the spatially-variable diffusivity to first
order in the elevation. The solution to this equation is a self-affine or
fractal surface with linear transects that have power spectra S(k) is
proportional to k^-1.8, independent of the age of the topography, consistent
with observations. The hypsometry produced by the model is skewed such that
lowlands make up a larger area than highlands as in real topography. In the
second analysis we include river networks explicitly in a numerical simulation
by calculating... Abstract continued in paper.


title:
Statistical analysis and modeling of variations of the earth's magnetic
  field

abstract:
  Power spectral analyses of the dipole moment of the earth's magnetic field
inferred from ocean sediment cores and archeomagnetic data from time scales of
100 yr to 4 Myr have been carried out. The power spectrum is proportional to
1/f where f is the frequency. These analyses compliment previous work which has
established a 1/f^2 spectrum for variations at time scales less than 100 yr.
Power spectral analyses of inclination and declination inferred from lake
sediments from time scales of 10 yr to 30 kyr have also been performed. The
spectra are constant above time scales of 3 kyr, proportional to 1/f^2 from
time scales of 500 yr to 3 kyr, and constant again below time scales of 500 yr.
The 3 kyr time scale is associated with the decay time of the quadrupole
moment. We test the hypothesis that reversals are the result of variations in
dipole intensity with a 1/f spectrum which occasionally are large enough to
cross the zero intensity value. Synthetic binormal time series with a 1/f power
spectrum representing variations in the earth's dipole moment are constructed.
Synthetic reversals from these time series exhibit statistics in good agreement
with the reversal record. 1/f noise behavior is reproduced with a model of
magnetic diffusion in the earth's core driven by dynamo action modeled as a
random amplification or destruction of the local magnetic field.


title:
Scale-invariance of soil moisture variability and its implications for
  the frequency-size distribution of landslides

abstract:
  Power spectral analyses of soil moisture variability are carried out from
scales of 100 m to 10 km on the microwave remotely-sensed data from the Washita
experimental watershed during 1992. The power spectrum S(k) has an
approximately power-law dependence on wave number k with exponent -1.8. This
behavior is consistent with the behavior of a stochastic differential equation
for soil moisture at a point. This behavior has important consequences for the
frequency-size distribution of landslides. We present the cumulative
frequency-size distributions of landslides induced by precipitation in Japan
and Bolivia as well as landslides triggered by the 1994 Northridge, California
earthquake. Large landslides in these regions, despite being triggered by
different mechanisms, have a cumulative frequency-size distribution with a
power-law dependence on area with an exponent ranging from -1.5 to -2. We use a
soil moisture field with the above statistics in conjunction with a slope
stability analysis to model the frequency-size distribution of landslides. In
our model landslides occur when a threshold shear stress dependent on cohesion,
pore pressure, internal friction and slope angle is exceeded. This implies a
threshold dependence on soil moisture and slope angle since these factors are
primarily dependent on soil moisture. Abstract continued in paper.


title: A two-dimensional network simulator for two-phase flow in porous media

abstract:
  We investigate a two-dimensional network simulator capable of modeling
different time dependencies in two-phase drainage displacements. In particular,
we focus on the temporal evolution of the pressure due to capillary and viscous
forces and the time dependence of the interface between the two liquids. The
dynamics of the capillary effect are taken into account and we report on high
accuracy pressure measurements. Moreover, the simulator includes important
features in drainage, like burst dynamics of the invading fluid and
simultaneous flow of two liquids in a section of a tube. The validity of the
model is checked by comparing simulation results with well known experimental
properties in drainage displacement.


title:
Cylindrical ideal magnetohydrodynamic equilibria with incompressible
  flows

abstract:
  It is proved that (a) the solutions of the ideal magnetohydrodynamic
equation, which describe the equlibrium states of a cylindrical plasma with
purely poloidal flow and arbitrary cross sectional shape [G. N.
Throumoulopoulos and G. Pantis, Plasma Phys. and Contr. Fusion 38, 1817 (1996)]
are also valid for incompressible equlibrium flows with the axial velocity
component being a free surface quantity and (b) for the case of isothermal
incompressible equilibria the magnetic surfaces have necessarily circular cross
section.


title: Self-affine time series: applications and models

abstract:
  A review paper considering space-time variability of climate, sedimentation,
and geomagnetism.


title: QED theory of the nuclear recoil effect in atoms

abstract:
  The quantum electrodynamic theory of the nuclear recoil effect in atoms to
all orders in \alpha Z is formulated. The nuclear recoil corrections for atoms
with one and two electrons over closed shells are considered in detail. The
problem of the composite nuclear structure in the theory of the nuclear recoil
effect is discussed.


title:
Lowest-energy representations of non-centrally extended diffeomorphism
  algebras

abstract:
  We describe a class of non-central extensions of the diffeomorphism algebra
in N-dimensional spacetime, and construct lowest-energy modules thereof, thus
generalizing work of Eswara-Rao and Moody. There is one representation for each
representation of $Vir\ltimes_{k_0}\km{gl(N)}$ (an extension of the semi-direct
product). Similar modules are constructed for gauge algebras.


title: Modeling Metallic Microstructure Using Moving Finite Elements

abstract:
  We present an efficient method for anealing 3d metallic grains using Gradient
Weighted Moving Finite Elements (GWMFE). The initial grain microstructure is
generated from Monte-Carlo evolution of a an effective discrete model on the
initial (frozen) unstructured grid generated for the external geometry of the
GWMFE calculation.


title:
Enhancement of the electric dipole moment of the electron in the YbF
  molecule

abstract:
  We calculate an effective electric field on the unpaired electron in the YbF
molecule. This field determines sensitivity of the molecular experiment to the
electric dipole moment of the electron. We use experimental value of the
spin-doubling constant to estimate the admixture of the configuration with the
hole in the 4f-shell of Ytterbium to the ground state of the molecule. This
admixture reduces the field by 7%. Our value for the effictive field is 5.1
a.u. = 2.5 10^{10} V/cm.


title: Anomalous Weight Behavior in YBa2Cu3O7 Compounds at Low Temperature

abstract:
  YBa2Cu3O7 high temperature superconductor samples were weighed on an
electronic balance during a warming cycle beginning at 77 degrees K. The
experiment was configured so that the YBa2Cu3O7 material was weighed along with
a magnet, a target mass, and liquid Nitrogen coolant. The weights were captured
during Nitrogen evaporation. Results indicated unexpected variations in the
system weight that appear as a function of temperature and possibly other
parameters.


title:
Mass-Diameter Relation of Globular Star Clusters, Elliptical Galaxies
  and Spherical Clusters of Galaxies

abstract:
  In a preceeding paper alternative reflections on gravitation were developed.
There it was assumed that the primary interaction between two masses is not of
attractive but of repulsive nature. The repulsive force results from the impuls
transfer produced by the gravitational radiation which is emitted and absorbed
by both masses. The observed attractive force between the two masses according
to Newton`s law of gravitation, however, is a secondary effect and a
consequence of the existence of all the masses in the universe. The mutual
screening of the gravitational radiation of all masses of the universe by the
two masses under consideration leads to the gravitational attraction between
them. The balance between primary, repulsive and secondary, attractive forces
can stabilize highly concentrated spherical mass accumulations with a linear
dependence of their mass on the square of their diameter. Such objects can
really be observed in the universe in the form of globular star clusters,
elliptical galaxies and spherical clusters of galaxies. The scatter of the data
of every group is rather large. But the collection of the objects of all three
groups, reaching from the smallest globular star cluster to the largest
spherical cluster of galaxies, with masses differing by almost 12 orders of
magnitude, clearly shows the proposed mass-diameter relation.


title: Alternative Reflections on Gravitation

abstract:
  It is assumed that the primary interaction between two masses m1 and m2 is
not attractive as postulated by Newton's law of gravitation, but repulsive.
Both m1 and m2 emit and absorb gravitational radiation. Corresponding to the
laws of optics the absorption is connected with an impulse transfer that
produces the repulsive force. If, however, m1 and m2 are embedded in the
gravitational radiation produced by all the masses of the universe the
absorption by m1 and m2 leads to a reduction of the intensity of the
gravitational radiation between them, thus creating an attractive force exactly
as described by Newton's law. The so called universal gravitational constant is
no constant. It locally depends on the arrangement of the masses in the
universe. It can accept high values which are usually explained by the
existence of dark matter. Due to the primary forces of repulsive nature between
all masses the expansion of the universe is an intrinsic property. The balance
between primary, repulsive and secondary, attractive gravitational forces can
stabilize highly concentrated mass accumulations as they are observed in
globular clusters and the bulges of galaxies.


title: Ultimate luminosities and energies of photon colliders

abstract:
  A photon collider luminosity and its energy are determined by the parameters
of an electron-electron linear collider (energy, power, beam emittances) and
collision effects. The main collision effect is the coherent e+e- pair
creation. At low energies (2E < 0.5 - 1 TeV) this process is suppressed due to
repulsion of electron beams. In this region gamma-gamma luminosity above
10^{35} cm-2 s-1 is possible (10^{33} is sufficient). At higher energies the
limited average beam power and coherent pair creation restrict the maximum
energy of photon colliders (with sufficient luminosity) at 2E ~ 5 TeV.
Obtaining high luminosities requires the development of new methods of
production beams with low emittances such as a laser cooling.


title: Virasoro character identities and Artin L-functions

abstract:
  Some identities between unitary minimal Virasoro characters at levels 3, 4
and 5 are shown to arise as a consequence of relations between Artin
L-functions of different quadratic fields. The definitions and concepts of
number theory necessary to present the theta function identities which can be
derived from these relations are introduced. A new infinite family of
identities between Virasoro characters is obtained as a by-product.


title:
Dispersion Relation of a Ferrofluid Layer of Any Thickness and Viscosity
  in a Normal Magnetic Field; Asymptotic Regimes

abstract:
  We have calculated the general dispersion relationship for surface waves on a
ferrofluid layer of any thickness and viscosity, under the influence of a
uniform vertical magnetic field. The amplification of these waves can induce an
instability called peaks instability (Rosensweig instability). The expression
of the dispersion relationship requires that the critical magnetic field and
the critical wavenumber of the instability depend on the thickness of the
ferrofluid layer. The dispersion relationship has been simplified into four
asymptotic regimes: thick or thin layer and viscous or inertial behaviour. The
corresponding critical values are presented. We show that a typical parameter
of the ferrofluid enables one to know in which regime, viscous or inertial, the
ferrofluid will be near the onset of instability.


title: Invariant tensors for simple groups

abstract:
  The forms of the invariant primitive tensors for the simple Lie algebras A_l,
B_l, C_l and D_l are investigated. A new family of symmetric invariant tensors
is introduced using the non-trivial cocycles for the Lie algebra cohomology.
For the A_l algebra it is explicitly shown that the generic forms of these
tensors become zero except for the l primitive ones and that they give rise to
the l primitive Casimir operators. Some recurrence and duality relations are
given for the Lie algebra cocycles. Tables for the 3- and 5-cocycles for su(3)
and su(4) are also provided. Finally, new relations involving the d and f su(n)
tensors are given.


title: The El Nino Stochastic Oscillator

abstract:
  Anomalies during an El Nino are dominated by a single, irregularly
oscillating, mode. Equatorial dynamics has been linked to delayed-oscillator
models of this mode. Usually, the El Nino mode is regarded as an unstable mode
of the coupled atmosphere system and the irregularity is attributed to noise
and possibly chaos. Here a variation on the delayed oscillator is explored. In
this stochastic-oscillator view, El Nino is a stable mode excited by noise. It
is shown that the autocorrelation function of the observed NINO3.4 index is
that of a stochastic oscillator, within the measurement uncertainty. Decadal
variations as would occur in a stochastic oscillator are shown to be comparable
to those observed, only the increase in the long-term mean around 1980 is
rather large. The observed dependence of the seasonal cycle on the variance and
the correlation is so large that it can not be attributed to the natural
variability of a stationary stochastic oscillator. So the El Ni\~{n}o
stochastic-oscillator parameters must depend on the season. A forecast model
based on the stochastic oscillator with a variance that depends on the season
has a skill that approaches that of more comprehensive statistical models: over
the period 1982-1993, the anomaly correlation is 0.65 for two-season lead
forecasts.


title:
Mean-field analysis of a dynamical phase transition in a cellular
  automaton model for collective motion

abstract:
  A cellular automaton model is presented for random walkers with biologically
motivated interactions favoring local alignment and leading to collective
motion or swarming behavior. The degree of alignment is controlled by a
sensitivity parameter, and a dynamical phase transition exhibiting spontaneous
breaking of rotational symmetry occurs at a critical parameter value. The model
is analyzed using nonequilibrium mean field theory: Dispersion relations for
the critical modes are derived, and a phase diagram is constructed. Mean field
predictions for the two critical exponents describing the phase transition as a
function of sensitivity and density are obtained analytically.


title: Irrational Numbers of Constant Type --- A New Characterization

abstract:
  We obtain a new characterization for irrational numbers of constant type --
defined as irrationals with bounded partial quotients in their continued
fraction expansion. The result is essential in the formulation of stability
criteria for orbits of quantum twist maps in a class of dynamical systems.


title:
Second-order magnetic contributions to the hyperfine splitting of the
  5snd ^1D_2 states in ^87Sr

abstract:
  The hyperfine structure of 5snd ^1D_2 states in ^{87}Sr was studied for
principal quantum numbers 11 <= n <= 25 by Doppler-free two-photon excitation
combined with thermionic detection. Based on the more accurate data, compared
to previous results, the hyperfine structure was analysed by second order
perturbation theory using MQDT wavefunctions. As a result we find that the
surprisingly large B-factors obtained by fitting the data with the Casimir
formula do not reflect a quadrupolar interaction but rather consist
predominantly of second order magnetic dipole contributions. Further,
inconsistencies in the King plot of odd-even isotope shifts were removed by
this type of analysis. The result demonstrates the importance of higher order
effects in hyperfine splittings of excited states in atoms with two valence
electrons, even when the fine structure splitting is large compared to the
hyperfine splitting.


title: Quantum interference and particle trajectories

abstract:
  The existence of precise particle trajectories in any quantum state is
accounted for in a consistent way by allowing delocalization of the particle
charge. The relativistic mass of the particle remains within a small volume
surrounding a singularity moving along the particle trajectory. The singularity
is the source of an electric displacement field. The field induces a
polarization charge in the vacuum and this charge is equated with the charge of
the particle. Under dynamic conditions a distributed charge density rho(x,t) is
induced in the vacuum. The volume integral of the charge density is equal to
the charge of the particle and is rigorously conserved. The charge density is
derived from a complex-valued physical field psi(x,t) such that rho(x,t) =
|psi(x,t)|^2. The position probability density is equated with the mean charge
density. The mean field psi(x,t) for many sample realizations with a given
energy E and potential V(x) is the sum of the individual fields. In order for
the sum to be non-zero, the components in the spectral decompositions of the
individual fields must be spatially coherent. The particle has a spin frequency
given by Planck's relation hv = T - V + mc^2, where T is the kinetic energy,
determined from the momentum p and V is a quantum potential such that E = T + V
is conserved. The instantaneous phase of the spin is given by the phase of
exp(ikx) in the spectral decomposition a(k) of psi(x,t). It is spatially
coherent, due to the dependence on x. The momentum probability distribution is
given by the squared magnitude of the coefficients a(k). The Schrodinger
equation is derived by requiring local conservation of mean energy.


title:
Isotopic Grand Unification with the Inclusion of Gravity (revised
  version)

abstract:
  We introduce a dual lifting of unified gauge theories, the first
characterized by the isotopies, which are axiom- preserving maps into broader
structures with positive-definite generalized units used for the representation
of matter under the isotopies of the Poincare' symmetry, and the second
characterized by the isodualities, which are anti-isomorphic maps with
negative-definite generalized units used for the representation of antimatter
under the isodualities of the Poincare' symmetry. We then submit, apparently
for the first time, a novel grand unification with the inclusion of gravity for
matter embedded in the generalized positive-definite units of unified gauge
theories while gravity for antimatter is embedded in the isodual isounit. We
then show that the proposed grand unification provides realistic possibilities
for a resolution of the axiomatic incompatibilities between gravitation and
electroweak interactions due to curvature, antimatter and the fundamental
space-time symmetries.


title: Two electron dynamics in photodetachment

abstract:
  We present the results of experimental studies of photon-negative ion
interactions involving the dynamics of two electrons. Resonances associated
with doubly excited states of Li^- and He^- have been observed using laser
photodetachment spectroscopy. Total and partial photodetachment cross sections
have been investigated. In the former case, the residual atoms are detected
irrespective of their excitation state, while in the latter case only those
atoms in specific states are detected. This was achieved by the use of a state
selective detection scheme based on the resonant ionization of the residual
atoms. In addition, in the case of Li^- photodetachment, the threshold behavior
of the Li(2 ^2P)+e^-(ks) partial cross section has been used to accurately
measure the electron affinity of Li.


title: Recoil Correction to Hydrogen Energy Levels: A Revision

abstract:
  Recent calculations of the order (Z\alpha)^4(m/M)Ry pure recoil correction to
hydrogen energy levels are critically revised. The origins of errors made in
the previous works are elucidated. In the framework of a successive approach,
we obtain the new result for the correction to S levels. It amounts to -16.4
kHz in the ground state and -1.9 kHz in the 2S state.


title: The Analysis of Data from Continuous Probability Distributions

abstract:
  Conventional statistics begins with a model, and assigns a likelihood of
obtaining any particular set of data. The opposite approach, beginning with the
data and assigning a likelihood to any particular model, is explored here for
the case of points drawn randomly from a continuous probability distribution. A
scalar field theory is used to assign a likelihood over the space of
probability distributions. The most likely distribution may be calculated,
providing an estimate of the underlying distribution and a convenient graphical
representation of the raw data. Fluctuations around this maximum likelihood
estimate are characterized by a robust measure of goodness-of-fit. Its
distribution may be calculated by integrating over fluctuations. The resulting
method of data analysis has some advantages over conventional approaches.


title:
Some theoretical considerations concerning ion hydration in the case of
  ion transfer between water and 1,2-dichloroethane

abstract:
  Some aspects of direct ion transfer across the water/1,2-dichloroethane are
analyzed using a very simple model based on thermodynamic considerations. It
was concluded that ion solvation by water molecules may occur in some
particular cases in the organic phase, delivering an important contribution to
the Gibbs free energy of ion transfer between the aqueous and the organic
phase. In general terms, this particular type of transfer should be favored in
the case of highly charged small ions at interfaces with a relatively low
surface tension and a large difference between the reciprocal of the
corresponding dielectric constants.


title: Order reductions of Lorentz-Dirac-like equations

abstract:
  We discuss the phenomenon of preacceleration in the light of a method of
successive approximations used to construct the physical order reduction of a
large class of singular equations. A simple but illustrative physical example
is analyzed to get more insight into the convergence properties of the method.


title: Folding pathways of a helix-turn-helix model protein

abstract:
  A small model polypeptide represented in atomic detail is folded using Monte
Carlo dynamics. The polypeptide is designed to have a native conformation
similar to the central part of the helix-turn-helix protein ROP. Starting from
a beta-strand conformation or two different loop conformations of the protein
glutamine synthetase, six trajectories are generated using the so-called window
move in dihedral angle space. This move changes conformations locally and leads
to realistic, quasi-continuously evolving trajectories. Four of the six
trajectories end in stable native-like conformations. Their folding pathways
show a fast initial development of a helix-bend-helix motif, followed by a
dynamic behaviour predicted by the diffusion-collision model of Karplus and
Weaver. The phenomenology of the pathways is consistent with experimental
results.

categories: physics.bio-ph cond-mat.soft physics.chem-ph q-bio


title:
On the codon assignment of chain termination signals and the
  minimization of the effects of frameshift mutations

abstract:
  It has been suggested that the minimization of the probability for lethal
mutations is a major constraint shaping the genetic code, with the finding that
the genetic code is highly protective against transition mutations. Here, we
show that recent data on polymerase-induced frameshifts provide a rationale for
the codon assignment of chain termination signals (CTS).


title:
Polarization fluctuations in vertical cavity surface emitting lasers: a
  key to the mechanism behind polarization stability

abstract:
  We investigate the effects of the electron-hole spin dynamics on the
polarization fluctuations in the light emitted from a vertical cavity surface
emitting laser (VCSEL). The Langevin equations are derived based on a rate
equation model including birefringence, dichroism, and two carrier density
pools seperately coupled to right and left circular polarization. The results
show that the carrier dynamics phase lock the polarization fluctuations to the
laser mode. This is clearly seen in the difference between fluctuations in
ellipticity and fluctuations in polarization direction. Seperate measurements
of the polarization fluctuations in ellipticity and in polarization direction
can therefore provide quantitative information on the non-linear contribution
of the carrier dynamics to polarization stability in VCSELs.

categories: physics.optics adap-org cond-mat nlin.AO quant-ph


title: Theoretical Study of Small (NaI)n Clusters

abstract:
  A systematic theoretical study of stoichiometric clusters (NaI)n up to n=15
is performed using the ab initio Perturbed-Ion (PI) model. The structures
obtained are compared to previous pair potential results, and observed
differences between (NaI)n clusters and previous ab initio results for other
alkali halide clusters are discussed. (NaI)n clusters with n up to 15 do not
show yet a marked preference for geometries which are fragments of the bulk
lattice. Instead, stacks of hexagonal rings or more open structures are
obtained as ground structures in clusters with n=3, 6, 7, 9, 10, 12, 13 and 15,
indicating that convergence to bulk structure is not achieved yet at this size
range. Low lying isomers which are fragments of the crystal lattice exist,
nevertheless, for those cases. The binding energies show that clusters with
n=(4), 6, 9 and 12 molecules are specially stable. The binding energy has been
decomposed in contributions which allow for an intuitive interpretation. Some
electronic properties like ionization potentials and electronic energy levels
are also studied.


title: Lorentz Symmetry Violation and Very High-Energy Cross Sections

abstract:
  We discuss the implications of a recently proposed pattern of Lorentz
symmetry violation on very high-energy cross sections. As a consequence of the
breaking of local Lorentz invariance by the introduction of a fundamental
length, $a$ , the kinematics is modified and the properties of final states are
fundamentally different in collider-like (two incoming particles with equal,
opposite momenta with respect to the vacuum rest frame) and fixed-target (one
of the incoming particles at rest with respect to the vacuum rest frame)
situations. In the first case, the properties of the allowed final states are
similar to relativistic kinematics, as long as the relevant wave vectors are
much smaller than the critical wave vector scale $a^{-1}$ . But, if one of the
incoming particles is close to rest in the vacuum rest frame, energy
conservation reduces the final-state phase space at very high energy and can
lead to a sharp fall of cross sections starting at incoming-particle wave
vectors well below the inverse of the fundamental length. Then, the Froissart
bound may cease to be relevant, as total cross sections seem to become much
smaller than it would be allowed by local, Lorentz-invariant, field theory.
Important experimental implications of the new scenario are found for
cosmic-ray astrophysics and for very high-energy cosmic rays reaching the
earth.


title: Testing the Sprint Curve Model using the 150m Bailey-Johnson Showdown

abstract:
  Recently, a simple model was derived to account for a sprinter's energy loss
around a curve, based on previous sprint models for linear races. This paper
offers a quick test of the model's precision by comparing split times from
Donovan Bailey's 150m ``Challenge of Champions'' race at Skydome on June 1st,
1997. The discrepancy in the track configuration which almost prompted Bailey
to drop from the race is also addressed.


title: The ring imaging Cherenkov detector for the BRAHMS experiment at RHIC

abstract:
  A ring imaging Cherenkov counter, to be read out by four 100-channel PMTs, is
a key element of the BRAHMS experiment. We report here the most recent results
obtained tested at the BNL AGS using several radiator gases, including the
heavy fluorocarbon C4F10. Ring radii were measured for different particles
(pions, muons, and electrons) for momenta ranging from 2 to 12 GeV/c employing
pure C4F10 as radiator.


title: Objective Bayesian Statistics

abstract:
  Bayesian inference --- although becoming popular in physics and chemistry ---
is hampered up to now by the vagueness of its notion of prior probability. Some
of its supporters argue that this vagueness is the unavoidable consequence of
the subjectivity of judgements --- even scientific ones. We argue that priors
can be defined uniquely if the statistical model at hand possesses a symmetry
and if the ensuing confidence intervals are subjected to a frequentist
criterion. Moreover, it is shown via an example taken from recent experimental
nuclear physics, that this procedure can be extended to models with broken
symmetry.


title: The bound mu+ mu- system

abstract:
  We consider the hyperfine structure, the atomic spectrum and the decay
channels of the bound mu+ mu- system (dimuonium). The annihilation lifetimes of
low-lying atomic states of the system lie in the nanosecond range range. The
decay rates could be measured by detection of the decay products (high energy
photons or electron-positron pairs). The hyperfine structure splitting of the
dimuonic system and its decay rate are influenced by electronic vacuum
polarization effects in the far time-like asymptotic region. This constitutes a
previously unexplored kinematic regime. We evaluate next--to-leading order
radiative corrections to the decay rate of low-lying atomic states. We also
obtain order alpha^5 corrections to the hyperfine splitting of the 1S and 2S
levels.


title:
Kinetics of a Model Weakly Ionized Plasma in the Presence of Multiple
  Equilibria

abstract:
  We study, globaly in time, the velocity distribution $f(v,t)$ of a spatially
homogeneous system that models a system of electrons in a weakly ionized
plasma, subjected to a constant external electric field $E$. The density $f$
satisfies a Boltzmann type kinetic equation containing a full nonlinear
electron-electron collision term as well as linear terms representing
collisions with reservoir particles having a specified Maxwellian distribution.
We show that when the constant in front of the nonlinear collision kernel,
thought of as a scaling parameter, is sufficiently strong, then the $L^1$
distance between $f$ and a certain time dependent Maxwellian stays small
uniformly in $t$. Moreover, the mean and variance of this time dependent
Maxwellian satisfy a coupled set of nonlinear ODE's that constitute the
``hydrodynamical'' equations for this kinetic system. This remain true even
when these ODE's have non-unique equilibria, thus proving the existence of
multiple stabe stationary solutions for the full kinetic model. Our approach
relies on scale independent estimates for the kinetic equation, and entropy
production estimates. The novel aspects of this approach may be useful in other
problems concerning the relation between the kinetic and hydrodynamic scales
globably in time.


title: Molecular Modeling of Trifluoromethanesulfonic Acid for Solvation Theory

abstract:
  Reported here are theoretical calculations on the triflic acid and water,
establishing molecular scale information necessary to modeling of the
structure, thermodynamics, and ionic transport of Nafion membranes. To
characterize side chain flexibility and accessibility of the acid proton, free
energies for rotation of both carbon-sulfur and sulfur-oxygen (hydroxyl) bonds
are presented. The energetic barrier to rotation of the acid proton away from
the sulfonic acid oxygen plane is substantially flattened, with barrier less
than one kcal/mol, by electrostatic solvation. The activation free energy for
acid-water proton interchange is about 4.7 kcal/mol.


title: Distributions of Triplets in Genetic Sequences

abstract:
  Distributions of triplets in some genetic sequences are examined and found to
be well described by a 2-parameter Markov process with a sparse transition
matrix. The variances of all the relevant parameters are not large, indicating
that most sequences gather in a small region in the parameter space. Different
sequences have very near values of the entropy calculated directly from the
data and the two parameters characterizing the Markov process fitting the
sequence. No relevance with taxonomy or coding/noncoding is clearly observed.


title: Structural and Electronic Properties of Small Neutral (MgO)n Clusters

abstract:
  Ab initio Perturbed Ion (PI) calculations are reported for neutral
stoichiometric (MgO)n clusters (n<14). An extensive number of isomer structures
was identified and studied. For the isomers of (MgO)n (n<8) clusters, a full
geometrical relaxation was considered. Correlation corrections were included
for all cluster sizes using the Coulomb-Hartree-Fock (CHF) model proposed by
Clementi. The results obtained compare favorably to the experimental data and
other previous theoretical studies. Inclusion of correlaiotn is crucial in
order to achieve a good description of these systems. We find an important
number of new isomers which allows us to interpret the experimental magic
numbers without the assumption of structures based on (MgO)3 subunits. Finally,
as an electronic property, the variations in the cluster ionization potential
with the cluster size were studied and related to the structural isomer
properties.


title: Ground state hyperfine splitting of high Z hydrogenlike ions

abstract:
  The ground state hyperfine splitting values of high Z hydrogenlike ions are
calculated. The relativistic, nuclear and QED corrections are taken into
account. The nuclear magnetization distribution correction (the Bohr-Weisskopf
effect) is evaluated within the single particle model with the g_{S}-factor
chosen to yield the observed nuclear moment. An additional contribution caused
by the nuclear spin-orbit interaction is included in the calculation of the
Bohr-Weisskopf effect. It is found that the theoretical value of the wavelength
of the transition between the hyperfine splitting components in ^{165}Ho^{66+}
is in good agreement with experiment.


title:
Possible Effects of Lorentz Symmetry Violation on the Interaction
  Properties of Very High-Energy Cosmic Rays

abstract:
  Special relativity has been tested at low energy with great accuracy, but
these results cannot be extrapolated to the very high-energy region.
Introducing a critical distance scale, $a$ , below 10E-25 cm (the wavelength
scale of the highest-energy observed cosmic rays) allows to consider models,
compatible with standard tests of special relativity, where a small violation
of Lorentz symmetry ($a$ can, for instance, be the Planck length, around 10E-33
cm) produces dramatic effects on the interaction properties of very high-energy
particles. Lorentz symmetry violation may potentially solve all the basic
problems raised by the highest-energy cosmic rays (origin and energy,
propagation...). Furthermore, superluminal sectors of matter may exist and
release very high-energy ordinary particles or directly produce very
high-energy cosmic-ray events with unambiguous signatures in very large
detectors. We discuss these phenomena, as well as the cosmic-ray energy range
(well below the energy scale associated to the fundamental length) and
experiments where they could be detected and studied.


title:
A solution of the spacetime singularity problem in relativistic
  cosmology by using an additional variable

abstract:
  The spacetime singularity in relativistic cosmology is cancelled by using an
additional variable. That is, the singularity-free models for an expanding
universe are obtained from general relativity.


title:
A solution of the measurement problem in quantum mechanics by using a
  variable hidden in Newtonian mechanics

abstract:
  The problem of a correct description of the physical phenomena of the
Heisenberg uncertainty relation is solved by using a variable hidden in
Newtonian mehcanics.


title: Progress in Photon Colliders

abstract:
  Last two years were very important in history of a photon colliders. This
option is included now in conceptual design reports of the NLC, JLC and
TESLA/SBLC projects. All the designs foresee two interaction regions: one for
e+e- and the second for gamma-gamma, gamma-e and e^-e^- collisions. This paper
is focused on three aspects: 1) arguments for photon colliders; 2) parameters
of current projects; 3) ultimate luminosities and energies, new ideas. Recent
studies have shown that the main collision effect - coherent pair creation - is
suppressed at photon colliders with the energy (2E < 2 TeV) due to the beam
repulsion, and one can achieve, in principle, the gamma-gamma luminosity
exceeding 10^{35} cm^-2s^-1. The required electron beams with very small
emittances can be obtained, for example, using a laser cooling of electron
beams. This new method requires a laser with a power by one order of magnitude
higher than that required for the ``conversion'' of electrons to photons. Such
lasers are not available today, but hopefully they will appear by the time when
linear colliders will be built. High energy gamma-gamma, gamma-e colliders with
the luminosity comparable to that in e^+e^- collisions are beyond the
competition in study of many phenomena of particle physics.


title: The ANKA Injector

abstract:
  ANKA is a 2.5 GeV synchrotron radiation storage ring under construction at
the Forschungszentrum Karlsruhe in Germany. The injector system will consist of
a pre-injector with an end energy of 20 to 50 MeV and a 0.5 GeV booster
synchrotron. In the following three different concepts for designing the
booster synchrotron are compared.


title: A Physics of Bounded Metric Spaces

abstract:
  We consider the possibility of obtaining emergent properties of physical
spaces endowed with structures analogous to that of collective models put
forward by classical statistical physics. We show that, assuming that a
so-called "metric scale" does exist, one can indeed recover a number of
properties of physical spaces such as the Minkowski metric, the relativistic
quantum dynamics and the electroweak theory.


title:
Interactions and Strings in Higher Order Anisotropic and Inhomogeneous
  Superspaces and Isospaces

abstract:
  The monograph gives a general geometric background of the theory of field
interactions, strings and diffusion processes on spaces, superspaces and
isospaces with higher order anisotropy and inhomogenity. Our approach proceeds
by developing the concept of higher order anisotropic superspace which unify
the logical and mathematical aspects of modern Kaluza-Klein theories and
generalized Lagrange and Finsler geometry and leads to modelling of physical
processes on higher order fiber bundles provided with nonlinear and
distingushed connections and metric structures. The view adopted in the
monograph is that a general field theory should incorporate all possible
anisotropic and stochastic manifestations of classical and quantum interactions
and, in consequence, a corresponding modification of basic principles and
mathematical methods in formulation of physical theories. This book can be also
considered as a pedagogical survey on the mentioned subjects.


title:
Conceptual and Experimental Feasibility Study of a Superconductive
  Micro-Undulator

abstract:
  In this paper the concept and the first successful tests towards constructing
a superconductive micro-undulator with a period length of 3.8 mm are described.
The structures were built with a commercially available NbTi wire. A full 100
periods prototype is now under construction.


title:
Time-Dependent Local Density Approximation for Collective Excitations of
  Atomic Clusters

abstract:
  We discuss the calculation of collective excitations in atomic clusters using
the time-dependent local density approximation. In principle there are many
formulations of the TDLDA, but we have found that a particularly efficient
method for large clusters is to use a coordinate space mesh and the algorithms
for the operators and the evolution equations that had been developed for the
nuclear time-dependent Hartree-Fock theory. The TDLDA works remarkably well to
describe the strong excitations in alkali metal clusters and in carbon
clusters. We show as an example the benzene molecule, which has two strong
features in its spectrum. The systematics of the linear carbon chains is well
reproduced, and may be understood in rather simple terms.


title:
General dispersion equation for oscillations and waves in
  non-collisional Maxwellian plasmas

abstract:
  We propose a new and effective method to find plasma oscillatory and wave
modes. It implies searching a pair of poles of two-dimensional (in coordinate
$x$ and time $t$) Laplace transform of self-consistent plasma electric field
$E(x,t) \to E_{p_1p_2}$, where $p_1 \equiv -i \omega$, $p_2 \equiv i k$ are
Laplace transform parameters, that is determining a pair of zeros of the
following equation $$\frac1{E_{p_1p_2}} = 0 .$$ This kind of conditional
equation for searching double poles of $E_{p_1p_2}$ we call ``general
dispersion equation'', so far as it is used to find the pair values
($\omega^{(n)}, k^{(n)}$), $n=1, 2, ...$ . It differs basically from the
classic dispersion equation $\epsilon_l(\omega,k) = 0$ (and is not its
generalization), where $\epsilon_l$ is longitudinal dielectric susceptibility,
its analytical formula being derived according to Landau analytical
continuation. In distinction to $\epsilon_l$, which is completely plasma
characteristic, the function $E_{p_1p_2}$ is defined by initial and boundary
conditions and allows one to find all the variety of asymptotical plasma modes
for each concrete plasma problem. In this paper we demonstrate some
possibilities of applying this method to the simplest cases of collisionless
ion-electron plasma and to electron plasma with collisions described by a
collision-relaxation term $-\nu f^{(1)}$.


title: Observation of the Dynamic Beta Effect at CESR with CLEO

abstract:
  Using the silicon strip detector of the CLEO experiment operating at the
Cornell Electron-positron Storage Ring (CESR), we have observed that the
horizontal size of the luminous region decreases in the presence of the
beam-beam interaction from what is expected without the beam-beam interaction.
The dependence on the bunch current agrees with the prediction of the dynamic
beta effect. This is the first direct observation of the effect.


title: Experiments on Critical Phenomena in a Noisy Exit Problem

abstract:
  We consider noise-driven exit from a domain of attraction in a
two-dimensional bistable system lacking detailed balance. Through analog and
digital stochastic simulations, we find a theoretically predicted bifurcation
of the most probable exit path as the parameters of the system are changed, and
a corresponding nonanalyticity of the activation energy. We also investigate
the extent to which the bifurcation is related to the local breaking of
time-reversal invariance.


title: Strong nonlinear regime of resonant four-wave mixing in a gas

abstract:
  The explicit solution is obtained for Raman four-wave mixing
$\omega_4=\omega_1-\omega_2+\omega_3$ of two strong fields $E_1, E_3$ and two
weak fields $E_2, E_4$ in a four-level system with the large Doppler
broadening. The resonance of the mixing coefficient vs intensity is found near
equal Rabi frequencies of strong fields and interpreted as an intersection of
quasi-energy levels. Up to 6 peaks appear in the dependence of conversion
coefficient on the detuning of the probe field. An unexpected additional pair
of peaks is a result of averaging over velocities and disappears at low
temperature. The effects allow explaining saturation behavior in recent
experiments on the mixing in sodium molecular vapor.


title: Model for Trapped Ion interacting with Standing Wave

abstract:
  We treat the interaction of a trapped ion with a standing-wave light field
relaxing the previous condition of the trapping ion being on the node of the
standing wave. In addition we work to second order in the Lamb-Dicke parameter
$\eta$, the extension to higher orders in $\eta$ is also indicated. Only a
simple transformation to the ``dressed basis'' [subject to the constraint of
Pauli algebra] is required in order to show that the ion interacting with a
standing light-wave may be described by the Jaynes-Cummings Hamiltonian.


title:
Maximal Abelian Subgroups of the Isometry and Conformal Groups of
  Euclidean and Minkowski Spaces

abstract:
  The maximal Abelian subalgebras of the Euclidean e(p,0) and pseudoeuclidean
e(p,1)Lie algebras are classified into conjugacy classes under the action of
the corresponding Lie groups E(p,0) and E(p,1), and also under the conformal
groups O(p+1,1) and O(p+1,2), respectively. The results are presented in terms
of decomposition theorems. For e(p,0) orthogonally indecomposable MASAs exist
only for p=1 and p=2. For e(p,1), on the other hand, orthogonally
indecomposable MASAs exist for all values of p. The results are used to
construct new coordinate systems in which wave equations and Hamilton-Jacobi
equations allow the separation of variables.


title:
Transition energy and lifetime for the ground state hyperfine splitting
  of high Z lithiumlike ions

abstract:
  The ground state hyperfine splitting values and the transition probabilities
between the hyperfine structure components of high Z lithiumlike ions are
calculated in the range $Z=49-83$. The relativistic, nuclear, QED and
interelectronic interaction corrections are taken into account. It is found
that the Bohr-Weisskopf effect can be eliminated in a combination of the
hyperfine splitting values of the hydrogenlike and lithiumlike ions of an
isotope. This gives a possibility for testing the QED effects in a combination
of the strong electric and magnetic fields of the heavy nucleus. Using the
experimental result for the $1s$ hyperfine splitting in ^{209}Bi^{82+}, the 2s
hyperfine splitting in ^{209}Bi^{80+} is calculated to be \Delta E=0.7969(2)
eV.


title: Semiconductor Lasers and Kolmogorov Spectra

abstract:
  In this article, we make a prima facie case that there could be distinct
advantages to exploiting a new class of finite flux equilibrium solutions of
the Quantum Boltzmann equation in semiconductor lasers.


title:
Common Molecular Dynamics Algorithms Revisited: Accuracy and Optimal
  Time Steps of Stoermer-Leapfrog Integrators

abstract:
  The Stoermer-Verlet-leapfrog group of integrators commonly used in molecular
dynamics simulations has long become a textbook subject and seems to have been
studied exhaustively. There are, however, a few striking effects in performance
of algorithms which are well-known but have not received adequate attention in
the literature. A closer view of these unclear observations results in
unexpected conclusions. It is shown here that contrary to the conventional
point of view, the leapfrog scheme is distinguished in this group both in terms
of the order of truncation errors and the conservation of the total energy. In
this case the characteristic square growth of fluctuations of the total energy
with the step size, commonly measured in numerical tests, results from
additional interpolation errors with no relation to the accuracy of the
computed trajectory. An alternative procedure is described for checking energy
conservation of leapfrog-like algorithms which is free from interpolation
errors. Preliminary tests on a representative model system suggest that
standard step size values used at present are lower than necessary for accurate
sampling.


title:
Two-electron self-energy contribution to the ground state energy of
  heliumlike ions

abstract:
  The two-electron self-energy contribution to the ground state energy of
heliumlike ions is calculated both for a point nucleus and an extended nucleus
in a wide interval of Z. All the two-electron contributions are compiled to
obtain most accurate values for the two-electron part of the ground state
energy of heliumlike ions in the range Z=20-100. The theoretical value of the
ground state energy of heliumlike uranium, based on currently available theory,
is evaluated to be -261382.9(8) eV, without higher order one-electron QED
corrections.


title: Immersion Anomaly of Dirac Operator on Surface in R^3

abstract:
  In previous report (J. Phys. A (1997) 30 4019-4029), I showed that the Dirac
field confined in a surface immersed in $R^3$ by means of a mass type potential
is governed by the Konopelchenko-Kenmotsu-Weierstrass-Enneper equation. In this
article, I quantized the Dirac field and calculated the gauge transformation
which exhibits the gauge freedom of the parameterization of the surface. Then
using the Ward-Takahashi identity, I showed that the expectation value of the
action of the Dirac field is expressed by the Willmore functional and area of
the surface.


title:
Enhancement of the electric dipole moment of the electron in BaF
  molecule

abstract:
  We report results of ab initio calculation of the spin-rotational Hamiltonian
parameters including P- and P,T-odd terms for the BaF molecule. The ground
state wave function of BaF molecule is found with the help of the Relativistic
Effective Core Potential method followed by the restoration of molecular
four-component spinors in the core region of barium in the framework of a
non-variational procedure. Core polarization effects are included with the help
of the atomic Many Body Perturbation Theory for Barium atom. For the hyperfine
constants the accuracy of this method is about 5-10%.


title: Supersymmetric partner chirping of Newtonian free damping

abstract:
  We connect the classical free damping cases by means of Rosner's construction
in supersymmetric quantum mechanics. Starting with the critical damping, one
can obtain in the underdamping case a chirping of instantaneous physical
frequency \omega ^{2}(t) \propto \omega_{u}^{2}sech^2(\omega_{u}t), whereas in
the overdamped case the "chirping" is of the (unphysical) type \omega
^{2}(t)\propto\omega_{o}^{2}sec^{2}(\omega_{o}t), where \omega_{u}$ and
$\omega_{o} are the underdamped and overdamped frequency parameters,
respectively


title: Involutive Spacetime Distributions and p-Brane Dynamics

abstract:
  We propose a precise definition of multidimensional fluids generated by
self-gravitating extended objects such as strings and membranes: a
p-dimensional perfect fluid is a smooth involutive p-dimensional distribution
on a spacetime, each integral manifold of which is a timelike, connected,
immersed submanifold of dimension, p -- representing the history of a
(p-1)-dimensional extended object. This geometric formulation of perfect fluids
of higher dimensions naturally leads to the associated stress-energy tensor.
Furthermore, the laws of temporal evolution and symmetries of such systems are
derived, in general, from the Einstein field equations and the integrability
conditions. We also present a matter model based on a 2-dimensional involutive
distribution, and it is shown that the stress-energy tensor for
self-gravitating strings gives rise to a non-trivial spherically symmetric
spacetime with a naked singularity.


title: The Weinberg Formalism and a New Look at the Electromagnetic Theory

abstract:
  In the first part of this paper we review several formalisms which give
alternative ways for describing the light. They are: the formalism `baroque'
and the Majorana-Oppenheimer form of electrodynamics, the Sachs' theory of
Elementary Matter, the Dirac-Fock-Podol'sky model, its development by
Staruszkiewicz, the Evans-Vigier ${\bf B}^{(3)}$ field, the theory with an
invariant evolution parameter by Horwitz, the analysis of the
action-at-a-distance concept, presented recently by Chubykalo and
Smirnov-Rueda, and the analysis of the claimed `longitudinality' of the
antisymmetric tensor field after quantization. The second part is devoted to
the discussion of the Weinberg formalism and its recent development by
Ahluwalia and myself. Connections between these models and possible
significance of longitudinal modes are also discussed.


title: Self/Anti-Self Charge Conjugate States for j=1/2 and j=1

abstract:
  We briefly review recent achievements in the theory of neutral particles (the
Majorana-McLennan-Case-Ahluwalia construct for self/anti-self charge conjugate
states for j=1/2 and j=1 cases). Among new results we present a theoretical
construct in which a fermion and an antifermion have the same intrinsic parity;
discuss phase transformations and find relations between the Majorana-like
field operator $\nu$, given by Ahluwalia, and the Dirac field operator. Also we
give explicit forms of the $j=1$ ``spinors" in the Majorana representation.


title: Stokes Parameters as a Minkowskian Four-vector

abstract:
  It is noted that the Jones-matrix formalism for polarization optics is a
six-parameter two-by-two representation of the Lorentz group. It is shown that
the four independent Stokes parameters form a Minkowskian four-vector, just
like the energy-momentum four-vector in special relativity. The optical filters
are represented by four-by-four Lorentz-transformation matrices. This
four-by-four formalism can deal with partial coherence described by the Stokes
parameters. A four-by-four matrix formulation is given for decoherence effects
on the Stokes parameters, and a possible experiment is proposed. It is shown
also that this Lorentz-group formalism leads to optical filters with a symmetry
property corresponding to that of two-dimensional Euclidean transformations.


title:
Dynamics of a polymer test chain in a glass forming matrix: The Hartree
  Approximation

abstract:
  In this paper the Martin-Siggia-Rose formalism is used to derive a
generalized Rouse equation for a test chain in a matrix which can undergo the
glass transition. It is shown that the surrounding matrix renormalizes the
static properties of the test chain. Furthermore the freezing of the different
Rouse modes is investigated. This yields freezing temperatures which depend
from the Rouse mode index.

categories: physics.chem-ph cond-mat.stat-mech math-ph math.MP


title: Isominkowskian formulation of gravity

abstract:
  We submit the viewpoint that, perhaps, some of the controversies in
gravitation occurred during this century are not due to insufficiencies of
Einstein's field equations, but rather to insufficiencies in the mathematics
used for their treatment. For this purpose we treat the same equations with the
novel, broader isomathematics and related isominkowskian geometry, and show an
apparently final resolution in favor of existing relativities of controversies
such as: the lack of invariance of the basic units of space and time; lack of
compatibility between gravitational and relativistic conservation laws; lack of
meaningful relativistic limit of gravitation; and others. However, an apparent
necessary condition for the resolution of these controversies is the
abandonment of the notion of curvature used in this century in favor of a
conceptual and mathematical broader notion. A number of intriguing implications
and experimental verifications are pointed out.


title:
Riccati parameter modes from Newtonian free damping motion by
  supersymmetry

abstract:
  We determine the class of damped modes \tilde{y} which are related to the
common free damping modes y by supersymmetry. They are obtained by employing
the factorization of Newton's differential equation of motion for the free
damped oscillator by means of the general solution of the corresponding Riccati
equation together with Witten's method of constructing the supersymmetric
partner operator. This procedure leads to one-parameter families of (transient)
modes for each of the three types of free damping, corresponding to a
particular type of %time-dependent angular frequency. %time-dependent,
antirestoring acceleration (adding up to the usual Hooke restoring
acceleration) of the form a(t)=\frac{2\gamma ^2}{(\gamma t+1)^{2}}\tilde{y},
where \gamma is the family parameter that has been chosen as the inverse of the
Riccati integration constant. In supersymmetric terms, they represent all those
one Riccati parameter damping modes having the same Newtonian free damping
partner mode


title:
Incorporation of the statistical uncertainty in the background estimate
  into the upper limit on the signal

abstract:
  We present a procedure for calculating an upper limit on the number of signal
events which incorporates the Poisson uncertainty in the background, estimated
from control regions of one or two dimensions. For small number of signal
events, the upper limit obtained is more stringent than that extracted without
including the Poisson uncertainty. This trend continues until the number of
background events is comparable with the signal. When the number of background
events is comparable or larger than the signal, the upper limit obtained is
less stringent than that extracted without including the Poisson uncertainty.
It is therefore important to incorporate the Poisson uncertainty into the upper
limit; otherwise the upper limit obtained could be too stringent.


title: Dissipative Dynamics of Collisionless Nonlinear Alfven Wave Trains

abstract:
  The nonlinear dynamics of collisionless Alfven trains, including resonant
particle effects is studied using the kinetic nonlinear Schroedinger (KNLS)
equation model. Numerical solutions of the KNLS reveal the dynamics of Alfven
waves to be sensitive to the sense of polarization as well as the angle of
propagation with respect to the ambient magnetic field. The combined effects of
both wave nonlinearity and Landau damping result in the evolutionary formation
of stationaryOA S- and arc-polarized directional and rotational
discontinuities. These waveforms are freqently observed in the interplanetary
plasma.

categories: physics.space-ph adap-org astro-ph nlin.AO nlin.PS patt-sol physics.plasm-ph


title: Buoyancy driven rotating boundary currents

abstract:
  The structure of boundary currents formed from intermediately dense water
introduced into a rotating, stably stratified, two-layer environment is
investigated in a series of laboratory experiments, performed for Froude
numbers ranging from 0.01 to 1. The thickness and streamwise velocity profiles
in quasi-steady currents are measured using a pH activated tracer (thymol blue)
and found to compare favorably to simplified analytic solutions and numerical
models. Currents flowing along sloping boundaries in a stratified background
exhibit robust stability at all experimental Froude numbers. Such stability is
in sharp contrast to the unequivocal instability of such currents flowing
against vertical boundaries, or of currents flowing along slopes in a uniform
background. The presence of a variety of wave mechanisms in the ambient medium
might account for the slower and wider observed structures and the stability of
the currents, by effecting the damping of disturbances through wave radiation.


title:
The nonstandard constrained KP hierarchy and the generalized Miura
  transformations

abstract:
  We consider the nonstandard constrained KP (ncKP) hierarchy which is obtained
from the multi-constraint KP hierarchy by gauge transformation. The second
Hamiltonian structure of the ncKP hierarchy can be simplified by factorizing
the Lax operator into multiplication form, thus the generalized Miura
transformation is obtained. We also discuss the free field realization of the
associated W-algebra.


title: A Numerical Study of Absorption by Multilayered Biperiodic Structures

abstract:
  We study the electromagnetic scattering by multilayered biperiodic aggregates
of dielectric layers and gratings of conducting plates. We show that the
characteristic lengths of such structures provide a good control of absorption
bands. The influence of the physical parameters of the problem (sizes,
impedances) is discussed.


title:
Time-dependent control of ultracold atoms and Bose-Einstein condensates
  in magnetic traps

abstract:
  With radiofrequency fields one can control ultracold atoms in magnetic traps.
These fields couple the atomic spin states, and are used in evaporative cooling
which can lead to Bose-Einstein condensation in the atom cloud. Also, they can
be used in controlled release of the condensate from the trap, thus providing
output couplers for atom lasers. In this paper we show that the time-dependent
multistate models for these processes have exact solutions which are
polynomials of the solutions of the corresponding two-state models. This allows
simple, in many cases analytic descriptions for the time-dependent control of
the magnetically trapped ultracold atoms.


title: A differential geometric approach to singular perturbations

abstract:
  A differential geometric approach to singular perturbation theory is
presented. It is shown that singular perturbation problems such as
multiple-scale and boundary layer problems can be treated more easily on a
differential geometric basis. A general method is proposed based on
differential forms and Lie-derivatives. Examples from multiple scale theory,
boundary layer theory and WKB-theory are given and it is demonstrated that
without the a priori knowledge of the scaling behaviour of the problem the
correct asymptotic expansion can be derived with the aid of differential forms.
The method is well suited for a mechanical implementation in computer algebra
programs.


title: To Foundations of Classical Electrodynamics

abstract:
  In the present work foundations of the law of the energy conservation and the
introduction of particles in the classical electrodynamics are discussed. We
pay attention to a logic error which takes place at an interpretation of the
Poynting's theorem as the law of conservation of energy. It was shown that the
laws of conservation of energy and momentum of the system of electromagnetic
fields and charged particles does not follow from the equations of
electrodynamics and the violation of these laws is displayed at the energy
change of particles. Particular examples are considered which make it possible
to restrict a possible kind of fields of a non-electromagnetic origin. We hope
that this work will permit to produce a more comprehensive analysis and to
stimulate the next step to the development of the foundations of the classical
and quantum electrodynamics.


title:
Optimized random phase approximations for arbitrary reference systems:
  extremum conditions and thermodynamic consistence

abstract:
  The optimized random phase approximation (ORPA) for classical liquids is
re-examined in the framework of the generating functional approach to the
integral equations. We show that the two main variants of the approximation
correspond to the addition of the same correction to two different first order
approximations of the homogeneous liquid free energy. Furthermore, we show that
it is possible to consistently use the ORPA with arbitrary reference systems
described by continuous potentials and that the same approximation is
equivalent to a particular extremum condition for the corresponding generating
functional. Finally, it is possible to enforce the thermodynamic consistence
between the thermal and the virial route to the equation of state by requiring
the global extremum condition on the generating functional.


title: Generalized Morse Potential: Symmetry and Satellite Potentials

abstract:
  We study in detail the bound state spectrum of the generalized Morse
potential~(GMP), which was proposed by Deng and Fan as a potential function for
diatomic molecules. By connecting the corresponding Schr\"odinger equation with
the Laplace equation on the hyperboloid and the Schr\"odinger equation for the
P\"oschl-Teller potential, we explain the exact solvability of the problem by
an $so(2,2)$ symmetry algebra, and obtain an explicit realization of the latter
as $su(1,1) \oplus su(1,1)$. We prove that some of the $so(2,2)$ generators
connect among themselves wave functions belonging to different GMP's (called
satellite potentials). The conserved quantity is some combination of the
potential parameters instead of the level energy, as for potential algebras.
Hence, $so(2,2)$ belongs to a new class of symmetry algebras. We also stress
the usefulness of our algebraic results for simplifying the calculation of
Frank-Condon factors for electromagnetic transitions between rovibrational
levels based on different electronic states.


title:
High orders of the perturbation theory for hydrogen atom in magnetic
  field

abstract:
  The states of hydrogen atom with principal quantum number $n\le3$ and zero
magnetic quantum number in constant homogeneous magnetic field ${\cal H}$ are
considered. The coefficients of energy eigenvalues expansion up to 75th order
in powers of ${\cal H}^2$ are obtained for these states. The series for energy
eigenvalues and wave functions are summed up to ${\cal H}$ values of the order
of atomic magnetic field. The calculations are based on generalization of the
moment method, which may be used in other cases of the hydrogen atom
perturbation by a polynomial in coordinates potential.


title: Nuclear Field Theory and Chiral Symmetry on a Calabi-Yau Manifold

abstract:
  The purpose of this contribution is to show how a nuclear field theory
follows naturally from the structure of four-dimensional Riemannian geometry. A
Yang-Mills field is introduced by constructing fibres that include all possible
exchanges of spin, parity and charge such that the collective quantum numbers
remain the same. In this way O(4) internal symmetry transformations are found
and a connection is obtained by exponentiation of a CP-invariant operator C
associated with the ground state. The metric is Calabi-Yau and Einstein. Carbon
13 is chosen as an example because it is the lightest nucleus to exhibit small
spin mutations even though there is no deformation parameter in the O(4)
commutation relations. Instead a supersymmetric transformation replaces a
quantum group. Mirror symmetry is also discussed.


title:
Averaging theory for the structure of hydraulic jumps and separation in
  laminar free-surface flows

abstract:
  We present a simple viscous theory of free-surface flows in boundary layers,
which can accommodate regions of separated flow. In particular this yields the
structure of stationary hydraulic jumps, both in their circular and linear
versions, as well as structures moving with a constant speed. Finally we show
how the fundamental hydraulic concepts of subcritical and supercritical flow,
originating from inviscid theory, emerge at intermediate length scales in our
model.


title:
A Bicharacteristic Scheme for the Numerical Computation of
  Two-Dimensional Converging Shock Waves

abstract:
  A 2d unsteady bicharacteristic scheme with shock fitting is presented and its
characteristic step, shock point step and boundary step are described. The
bicharacteristic scheme is compared with an UNO scheme and the Moretti scheme.
Its capabilities are illustrated by computing a converging, deformed shock
wave.


title:
Hurst's Rescaled Range Statistical Analysis for Pseudorandom Number
  Generators used in Physical Simulations

abstract:
  The rescaled range statistical analysis (R/S) is proposed as a new method to
detect correlations in pseudorandom number generators used in Monte Carlo
simulations. In an extensive test it is demonstrated that the RS analysis
provides a very sensitive method to reveal hidden long run and short run
correlations. Several widely used and also some recently proposed pseudorandom
number generators are subjected to this test. In many generators correlations
are detected and quantified.


title:
Reflection of light from a disordered medium backed by a
  phase-conjugating mirror

abstract:
  This is a theoretical study of the interplay of optical phase-conjugation and
multiple scattering. We calculate the intensity of light reflected by a
phase-conjugating mirror when it is placed behind a disordered medium. We
compare the results of a fully phase-coherent theory with those from the theory
of radiative transfer. Both methods are equivalent if the dwell time
\tau_{dwell} of a photon in the disordered medium is much larger than the
inverse of the frequency shift 2\Delta\omega acquired at the phase-conjugating
mirror. When \tau_{dwell} \Delta\omega < 1, in contrast, phase coherence
drastically affects the reflected intensity. In particular, a minimum in the
dependence of the reflectance on the disorder strength disappears when
\Delta\omega is reduced below 1/\tau_{dwell}. The analogies and differences
with Andreev reflection of electrons at the interface between a normal metal
and a superconductor are discussed.


title:
Quantum and Semiclassical Calculations of Cold Atom Collisions in Light
  Fields

abstract:
  We derive and apply an optical Bloch equation (OBE) model for describing
collisions of ground and excited laser cooled alkali atoms in the presence of
near-resonant light. Typically these collisions lead to loss of atoms from
traps. We compare the results obtained with a quantum mechanical complex
potential treatment, semiclassical Landau-Zener models with decay, and a
quantum time-dependent Monte-Carlo wave packet (MCWP) calculation. We formulate
the OBE method in both adiabatic and diabatic representations. We calculate the
laser intensity dependence of collision probabilities and find that the
adiabatic OBE results agree quantitatively with those of the MCWP calculation,
and qualitatively with the semiclassical Landau-Zener model with delayed decay,
but that the complex potential method or the traditional Landau-Zener model
fail in the saturation limit.


title:
Protein structure prediction as a hard optimization problem: the genetic
  algorithm approach

abstract:
  Protein structure prediction can be shown to be an NP-hard problem; the
number of conformations grows exponentially with the number of residues. The
native conformations of proteins occupy a very small subset of these, hence an
exploratory, robust search algorithm, such as a genetic algorithm (GA), is
required. The dynamics of GAs tend to be complicated and problem-specific.
However, their empirical success warrants their further study. In this paper,
guidelines for the design of genetic algorithms for protein structure
prediction are determined. To accomplish this, the performance of the simplest
genetic algorithm is investigated for simple lattice-based protein structure
prediction models (which is extendible to real-space), using energy
minimization. The study has led us to two important conclusions for
`protein-structure-prediction-genetic-algorithms'. Firstly, they require high
resolution building blocks attainable by multi-point crossovers and secondly
they require a local dynamics operator to `fine tune' good conformations.
Furthermore, we introduce a statistical mechanical approach to analyse the
genetic algorithm dynamics and suggest a convergence criterion using a quantity
analogous to the free energy of population.


title: Self-pinching of a relativistic electron bunch in a drift tube

abstract:
  Electron bunches with charge densities $\rho$ of the order of $10^2$ to
$10^3$ [nC/cm$^3$], energies between $20.$ and $100.$ [MeV], peak current
$>100$ [A], bunch lengths between 0.3 and 1.8 [cm], and bunch charge of 2.0 to
$20.$ [nC] are relevant to the design of Free Electron Lasers and future linear
colliders. In this paper we present the results of numerical simulations
performed with a particle in a cell (pic) code of an electron bunch in a drift
tube. The electron bunch has cylindrical symmetry with the $z$-axis oriented in
the direction of motion. The charge density distribution is constant in the
radial and Gaussian in the longitudinal direction, respectively. The electron
bunch experiences both a radial pinch in the middle of the pulse, corresponding
to the peak electron density, and a significant growth of the correlated
emittance. This behavior is explained, and an approximate scaling law is
identified. Comparisons of the results from the pic and PARMELA codes are
presented.

categories: physics.acc-ph physics.class-ph physics.comp-ph physics.plasm-ph


title: Gaussian limits for discrepancies. I: Asymptotic results

abstract:
  We consider the problem of finding, for a given quadratic measure of
non-uniformity of a set of $N$ points (such as $L_2$ star-discrepancy or
diaphony), the asymptotic distribution of this discrepancy for truly random
points in the limit $N\to\infty$. We then examine the circumstances under which
this distribution approaches a normal distribution. For large classes of
non-uniformity measures, a Law of Many Modes in the spirit of the Central Limit
Theorem can be derived.


title: The Geometry of SU(3)

abstract:
  The group SU(3) is parameterized in terms of generalized ``Euler angles''.
The differential operators of SU(3) corresponding to the Lie Algebra elements
are obtained, the invariant forms are found, the group invariant volume element
is found, and some relevant comments about the geometry of the group manifold
are made.


title:
The persistence of viscous effects in the overlap region, and the mean
  velocity in turbulent pipe and channel flows

abstract:
  We argue that important elements of the dynamics of wall-bounded flows reside
at the wall-normal position $y_p^+$ corresponding to the peak of the Reynolds
shear stress. Specializing to pipe and channel flows, we show that the mean
momentum balance in the neighborhood of $y_p^+$ is distinct in character from
those in the classical inner and outer layers. We revisit empirical data to
confirm that $y_p^+ = O(R^{1/2})$ and show that, in a neighborhood of order
$R^{1/2}$ around $y_p^+$, only the viscous effects balance pressure-gradient
terms. Here, R is the Reynolds number based on friction velocity and pipe
radius (or channel half-width). This observation provides a mechanism by which
viscous effects play an important role in regions traditionally thought to be
inviscid or inertial; in particular, it throws doubt on the validity of the
classical matching principle. Even so, it is shown that the classical
semi-logarithmic behavior for the mean velocity distribution can be a useful
approximation. It is argued that the recently advanced power-law profiles
possess a rich underlying structure, and could be good approximations to the
data over an extended region (but they too are unlikely to be exact).

categories: physics.flu-dyn chao-dyn cond-mat.stat-mech nlin.CD


title: Streamer propagation in magnetic field

abstract:
  The propagation of a streamer near an insulating surface under the influence
of a transverse magnetic field is theoretically investigated. In the weak
magnetic field limit it is shown that the trajectory of the streamer has a
circular form with a radius that is much larger than the cyclotron radius of an
electron. The charge distribution within the streamer head is strongly
polarized by the Lorentz force exerted perpendicualr to the streamer velocity.
A critical magnetic field for the branching of a streamer is estimated. Our
results are in good agreement with available experimental data.


title:
Possibility of Microturbulence Diagnostics in a Magnetically Confined
  Plasma Using Multiple Scattering Effects

abstract:
  The idea of new diagnostics method for the small-scale irregular structures
of magnetically confined plasma is suggested in the present paper. The method
can be based on measurements of intensity attenuation of the normal sounding
waves. Anomalous attenuation arises due to multiple scattering effects
investigated earlier for ionospheric radio propagation. It has been shown that
multiple scattering regime can realize in a tokamak plasma. Calculations of
normal sounding wave anomalous attenuation in a tokamak plasma have been
carried out. This quantity is large enough to be registered experimentally.


title:
Energy Calculation of Magnetohydrodynamic Waves and Their Stability For
  Viscous Shearing Flows

abstract:
  A self-consistent, thermodynamic approach is employed to derive the wave
energy of a magnetohydrodynamic system within the harmonic approximation and to
obtain the familiar dispersion relation from the resulting equation of motion.
The evolution of the system due to an external perturbation is studied by a
linear response formalism, that also gives the energy absorbed by the
magnetohydrodynamic system from the external field. The calculated wave energy
reveals the presence of positive and negative energy waves, that coalesce
together to give rise to Kelvin - Helmholtz instability of the system. The
threshold value of this instability changes only slightly in the presence of a
small amount of viscosity, thus precluding the dissipative instability of the
negative energy waves. The prediction of such a dissipative instability by
earlier authors turns out to be the result of an erroneous choice of the
viscous drag force, that violates the fundamental law of Galilean invariance.


title:
An energy conserving finite-difference model of Maxwell's equations for
  soliton propagation

abstract: The paper has been temporarily withdrawn by the authors.


title: Decoherent Histories and Non-adiabatic Quantum Molecular Dynamics

abstract:
  The role of quantum coherence loss in mixed quantum-classical dynamical
systems is explored in the context of the theory of quantum decoherence
introduced recently by Bittner and Rossky. (J. Chem. Phys. {\bf 103}, 8130
(1995)). This theory, which is based upon the consistent histories
interpretation of quantum mechanics, introduces decoherence in the quantum
subsystem by carefully considering the relevant time and length scales over
which one must consider the effects of phase interference between alternative
histories of the classical subsystem. Such alternative histories are an
integral part of any quantum-classical computational scheme which employ
transitions between discrete quantum states; consequently, the coherences
between alternative histories have a profound effect on the transition
probability between quantum states. In this paper, we review the Bittner-Rossky
theory and detail a computational algorithm suitable for large-scale quantum
molecular dynamics simulations which implements this theory. Application of the
algorithm towards the relaxation of a photoexcited aqueous electron compare
well to previous estimates of the excited state survival time as well as to the
experimental measurements.


title: Numerical Simulations of Free Radical Reactions

abstract:
  We present an overview of the role of quantum coherence in influencing
nonadiabatic processes in the condensed phase. Equations of motion for mixed
quantum-classical dynamics are derived from the Consistent Histories
interpretation of quantum mechanics. Application of the methods toward
computing the excited state lifetime of an excess electron in water and heavy
water provides a unique demonstration of our method.


title: Long Wavelength Broadband Sources of Coherent Radiation

abstract:
  Some considerations of long wavelength and broadband radiation sources based
on the emission of the coherent radiation by a train of short relativistic
electron bunches moving in an open resonator along an arc-like or undulator
trajectories and some new versions of the transition radiation sources and long
wavelength sources based on storage rings are presented.


title:
Hydrogen atoms in neutron star atmospheres: Analytical approximations
  for binding energies

abstract:
  Analytical approximations are constructed for binding energies of hydrogen
atoms arbitrarily moving in magnetic fields 7\times10^{11} G to 2\times10^{13}
G, typical of magnetic neutron stars.


title:
The detective Modulation Transfer Function applied to scanned digital
  radiographic detectors

abstract:
  An extension of the traditional modulation transfer function (MTF), the
detective MTF, is proposed for the evaluation of the resolution of X-ray
imaging detectors with non-uniform efficiency on the scale of individual
detector elements. The dMTF is shown to give a better representation than does
the MTF of the improved resolution reported when the readout of the detectors
is enhanced.


title:
Neutral Mutations and Punctuated Equilibrium in Evolving Genetic
  Networks

abstract:
  Boolean networks may be viewed as idealizations of biological genetic
networks, where each node is represented by an on-off switch which is a
function of the binary output from some other nodes. We evolve connectivity in
a single Boolean network, and demonstrate how the sole requirement of
sequential matching of attractors may open for an evolution that exhibits
punctuated equilibrium.

categories: physics.bio-ph adap-org cond-mat.dis-nn cond-mat.stat-mech nlin.AO q-bio.MN


title: Symbolic calculus on the time-frequency half-plane

abstract:
  The study concerns a special symbolic calculus of interest for signal
analysis. This calculus associates functions on the time-frequency half-plane
f>0 with linear operators defined on the positive-frequency signals. Full
attention is given to its construction which is entirely based on the study of
the affine group in a simple and direct way. The correspondence rule is
detailed and the associated Wigner function is given. Formulas expressing the
basic operation (star-bracket) of the Lie algebra of symbols, which is
isomorphic to that of the operators, are obtained. In addition, it is shown
that the resulting calculus is covariant under a three-parameter group which
contains the affine group as subgroup. This observation is the starting point
of an investigation leading to a whole class of symbolic calculi which can be
considered as modifications of the original one.


title:
Lorentz Symmetry Violation and Superluminal Particles at Future
  Colliders

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).
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.
Furthermore, 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. In this context,
phenomena such as the absence of Greisen-Zatsepin-Kuzmin cutoff and the
stability of unstable particles at very high energy are basic properties of a
wide class of noncausal models where local Lorentz invariance is broken
introducing a fundamental length. Observable phenomena from Lorentz symmetry
violation and superluminal sectors of matter are expected at very short
wavelength scales, even if Lorentz symmetry violation remains invisible to
standard low-energy tests. We discuss signatures of this new physics at LHC and
at other possible future colliders.


title: A comparison between algebraic models of molecular spectroscopy

abstract:
  We discuss a symmetry-adapted algebraic (or vibron) model for molecular
spectroscopy. The model is formulated in terms of tensor operators under the
molecular point group. In this way, we have identified interactions that are
absent in previous versions of the vibron model, in which the Hamiltonian is
expressed in terms of Casimir operators and their products. The inclusion of
these new interactions leads to reliable spectroscopic predictions. As an
example we study the vibrational excitations of the methane molecule, and
compare our results with those obtained in other algebraic models.


title:
Quantum Time and Spatial Localization: An Analysis of the Hegerfeldt
  Paradox

abstract:
  Two related problems in relativistic quantum mechanics, the apparent
superluminal propagation of initially localized particles and dependence of
spatial localization on the motion of the observer, are analyzed in the context
of Dirac's theory of constraints. A parametrization invariant formulation is
obtained by introducing time and energy operators for the relativistic particle
and then treating the Klein-Gordon equation as a constraint. The standard,
physical Hilbert space is recovered, via integration over proper time, from an
augmented Hilbert space wherein time and energy are dynamical variables. It is
shown that the Newton-Wigner position operator, being in this description a
constant of motion, acts on states in the augmented space. States with strictly
positive energy are non-local in time; consequently, position measurements
receive contributions from states representing the particle's position at many
times. Apparent superluminal propagation is explained by noting that, as the
particle is potentially in the past (or future) of the assumed initial place
and time of localization, it has time to propagate to distant regions without
exceeding the speed of light. An inequality is proven showing the Hegerfeldt
paradox to be completely accounted for by the hypotheses of subluminal
propagation from a set of initial space-time points determined by the quantum
time distribution arising from the positivity of the system's energy. Spatial
localization can nevertheless occur through quantum interference between states
representing the particle at different times. The non-locality of the same
system to a moving observer is due to Lorentz rotation of spatial axes out of
the interference minimum.


title: Classical Markovian Kinetic Equations: Explicit Form and H-Theorem

abstract:
  The probabilistic description of finite classical systems often leads to
linear kinetic equations. A set of physically motivated mathematical
requirements is accordingly formulated. We show that it necessarily implies
that solutions of such a kinetic equation in the Heisenberg representation,
define Markov semigroups on the space of observables. Moreover, a general
H-theorem for the adjoint of such semigroups is formulated and proved provided
that at least locally, an invariant measure exists. Under a certain continuity
assumption, the Markov semigroup property is sufficient for a linear kinetic
equation to be a second order differential equation with nonegative-definite
leading coefficient. Conversely it is shown that such equations define Markov
semigroups satisfying an H-theorem, provided there exists a nonnegative
equilibrium solution for their formal adjoint, vanishing at infinity.


title:
Characterisation of low pressure VPE GaAs diodes before and after 24
  GeV/c proton irradiation

abstract:
  GaAs Schottky diode detectors have been fabricated upon Low Pressure Vapour
Phase Epitaxial GaAs. The devices were characterised before and after a $1.25
\times 10^{14}$~cm$^{-2}$ 24GeV/c proton fluence. The as fabricated Ti-GaAs
barrier height was measured, via two electrical methods, to be $0.81\pm0.005$
and $0.85\pm0.01$~eV and a space charge density of $2.8 \pm 0.2 \times
10^{14}$~cm$^{-3}$ was determined. The current was greater than that expected
for an ideal barrier with the excess attributed to generation current from the
bulk. The charge collection efficiency, determined from front alpha
illumination and 60 keV gamma irradiation, was inexcess of 95% at 50V reverse
bias. After irradiation the reverse current, measured for a bias of 200V at
20$^{o}$~C, increased from 90~nA to 1500~nA due to radiation induced generation
centres. Deep levels were showed to be present using capacitance techniques.
The charge collection of the device determined from front alpha illumination
fell to $32\pm5$% at a reverse bias of 200V.


title: The effects of radiation on Gallium Arsenide radiation detectors

abstract:
  Semi-insulating, undoped, Liquid Encapsulated Czochralski (SI-U LEC) GaAs
detectors have been irradiated with 1MeV neutrons, 24GeV/c protons, and
300MeV/c pions. The maximum fluences used were 6, 3, and 1.8~10$^{14}$
particles/cm$^{2}$ respectively. For all three types of irradiation the charge
collection efficiencies (cce) of the detector are reduced due to the reduction
in the electron and hole mean free paths. Pion and proton irradiations produce
a greater reduction in cce than neutron irradiation with the pions having the
greatest effect. The effect of annealing the detectors at room temperature, at
200$^{o}$C and at 450$^{o}$C with a flash lamp have been shown to reduce the
leakage current and increase the cce of the irradiated detectors. The
flash-lamp anneal produced the greatest increase in the cce from 26% to 70% by
increasing the mean free path of the electrons. Two indium-doped samples were
irradiated with 24GeV/c protons and demonstrated no improvement over SI U GaAs
with respect to post-irradiation cce.


title: Recent results on GaAs detectors - 137

abstract:
  The present understanding of the charge collection in GaAs detectors with
respect to the materials used and its processing are discussed. The radiation
induced degradation of the charge collection efficiency and the leakage current
of the detectors are summarised. The status of strip and pixel detectors for
the ATLAS experiment are reported along with the latest results from GaAs X-ray
detectors for non-high energy physics applications.


title: Symplectic and Lie algebraic techniques in Geometric Optics

abstract:
  We will show the usefulness of the tools of Symplectic and Presymplectic
Geometry and the corresponding Lie algebraic methods in different problems in
Geometric Optics.


title:
A few remarks on integral representation for zonal spherical functions
  on the symmetric space $SU(N)/SO(N,\R)$

abstract:
  The integral representation on the orthogonal groups for zonal spherical
functions on the symmetric space $SU(N)/SO(N,\R)$ is used to obtain a
generating function for such functions. For the case N=3 the three-dimensional
integral representation reduces to a one-dimensional one.


title: Tracking down the ENSO delayed oscillator with an adjoint OGCM

abstract:
  The adjoint of an ocean general circulation model is used as a tool for
investigating the causes of changes in ENSO SST indices. We identify adjoint
Kelvin and Rossby waves in the sensitivities to sea level and wind stress at
earlier times, which can be traced back for more than a year through western
and weak eastern boundary reflections. Depending on the thermocline depth the
first and second baroclinic modes are excited. The sensitivities to the heat
flux and SST are local and decay in about a month. The sensitivities to the
fluxes are converted into the influence of SST using the adjoint of a
statistical atmosphere model. Focusing on SST perturbations in the index region
itself, we recover, up to a scale factor, the delayed oscillator concept.


title: An optical readout for a fibre tracker

abstract:
  The performance of 16 and 64 channel photomultipliers coupled to
scintillating fibres has been tested. The devices are sensitive to single
photoelectrons, show little gain losses for magnetic fields up to 100 Gauss and
have moderate optical cross-talk. The maximum channel to channel gain
variations reach a factor two for the 16 channel version and a factor of four
for the 64 channel PM. The measurements and simulations indicate that the
photomultipliers are well suited for the light detection in fibre trackers.


title: On the decay of Burgers turbulence

abstract:
  This work is devoted to the decay ofrandom solutions of the unforced Burgers
equation in one dimension in the limit of vanishing viscosity. The initial
velocity is homogeneous and Gaussian with a spectrum proportional to $k^n$ at
small wavenumbers $k$ and falling off quickly at large wavenumbers. In physical
space, at sufficiently large distances, there is an ``outer region'', where the
velocity correlation function preserves exactly its initial form (a power law)
when $n$ is not an even integer. When $1<n<2$ the spectrum, at long times, has
three scaling regions : first, a $|k|^n$ region at very small $k$\ms1 with a
time-independent constant, stemming from this outer region, in which the
initial conditions are essentially frozen; second, a $k^2$ region at
intermediate wavenumbers, related to a self-similarly evolving ``inner region''
in physical space and, finally, the usual $k^{-2}$ region, associated to the
shocks. The switching from the $|k|^n$ to the $k^2$ region occurs around a wave
number $k_s(t) \propto t^{-1/[2(2-n)]}$, while the switching from $k^2$ to
$k^{-2}$ occurs around $k_L(t)\propto t^{-1/2}$ (ignoring logarithmic
corrections in both instances). The key element in the derivation of the
results is an extension of the Kida (1979) log-corrected $1/t$ law for the
energy decay when $n=2$ to the case of arbitrary integer or non-integer $n>1$.
A systematic derivation is given in which both the leading term and estimates
of higher order corrections can be obtained. High-resolution numerical
simulations are presented which support our findings.