title: From Newton's Laws to the Wheeler-DeWitt Equation

abstract:
  This is a pedagogical paper which explains some ideas in cosmology at a level
accessible to undergraduate students. It does not use general relativity, but
uses the ideas of Newtonian cosmology worked out by Milne and McCrea. The
cosmological constant is also introduced within a Newtonian framework.
Following standard quantization procedures the Wheeler-DeWitt equation in the
minisuperspace approximation is derived for empty and non-empty universes.


title:
Qualitative analysis on the existence of bound excited states and
  low-lying resonances of the dipositronium

abstract:
  Symmetry has imposed very strong constraints on the structures of internal
wave functions and on the accessibility of outgoing channels. Based on symmetry
consideration, the existence of a number of bound excited states and low-lying
resonances has been suggested.


title:
Recurrence quantification analysis as a tool for the characterization of
  molecular dynamics simulations

abstract:
  A molecular dynamics simulation of a Lennard-Jones fluid, and a trajectory of
the B1 immunoglobulin G-binding domain of streptococcal protein G (B1-IgG)
simulated in water are analyzed by recurrence quantification, which is
noteworthy for its independence from stationarity constraints, as well as its
ability to detect transients, and both linear and nonlinear state changes. The
results demonstrate the sensitivity of the technique for the discrimination of
phase sensitive dynamics. Physical interpretation of the recurrence measures is
also discussed.


title: The lepton, quark and hadron currents

abstract:
  The Clifford pentads of the 4X4 complex matrices define the current vectors
of the particles. The weak isospin transformation divides the particles on two
components, which scatter in the 2-dimensional antidiagonal Clifford matrices
space. A physics objects move in the 3-dimensional diagonal Clifford matrices
space.
  This sectioning of the 5-dimensional space on the 3-dimensional and the
2-dimensional subspaces defines the Newtonian gravity principle.
  The Clifford pentads sextet contains single light pentad and three chromatic
pentads. The Cartesian frame rotations confound the chromatic pentads. The
combination of the chromatic particles (the hadron monad) exists, which behaves
as the particle for such rotations.
  PACS 12.15.-y 12.38.-t 12.39.-x 12.40.-q 04.20.-q


title:
The Schrodinger-like Equation for a Nonrelativistic Electron in a Photon
  Field of Arbitrary Intensity

abstract:
  The ordinary Schrodinger equation with minimal coupling for a nonrelativistic
electron interacting with a single-mode photon field is not satisfied by the
nonrelativistic limit of the exact solutions to the corresponding Dirac
equation. A Schrodinger-like equation valid for arbitrary photon intensity is
derived from the Dirac equation without the weak-field assumption. The
"eigenvalue" in the new equation is an operator in a Cartan subalgebra. An
approximation consistent with the nonrelativistic energy level derived from its
relativistic value replaces the "eigenvalue" operator by an ordinary number,
recovering the ordinary Schrodinger eigenvalue equation used in the formal
scattering formalism. The Schrodinger-like equation for the multimode case is
also presented.


title: Dielectric properties of interacting storage ring plasmas

abstract:
  A dielectric function including collisional correlations is derived by
linearizing the self consistent Vlasov equation with a Fokker-Planck collision
integral. The calculation yields the same type of dielectric function as in the
standard-theory of Schottky-noise in storage rings. This dielectric function is
compared with the Mermin-dielectric function derived from a kinetic equation
with relaxation time approximation. We observe that these functions are
identical, however the Mermin-DF is computationally advantageous. The limits of
both dielectric functions are given and the sum rules are proven. We apply
these dielectric functions for typical storage ring plasmas and calculate the
stopping power and the plasmon excitation spectrum.

categories: physics.acc-ph cond-mat.other nucl-th physics.plasm-ph


title:
Detector Construction Management and Quality Control: Establishing and
  Using a CRISTAL System

abstract:
  The CRISTAL (Cooperating Repositories and an Information System for Tracking
Assembly Lifecycles) project is delivering a software system to facilitate the
management of the engineering data collected at each stage of production of
CMS. CRISTAL captures all the physical characteristics of CMS components as
each sub-detector is tested and assembled. These data are retained for later
use in areas such as detector slow control, calibration and maintenance.
CRISTAL must, therefore, support different views onto its data dependent on the
role of the user. These data viewpoints are investigated in this paper. In the
recent past two CMS Notes have been written about CRISTAL. The first note, CMS
1996/003, detailed the requirements for CRISTAL, its relationship to other CMS
software, its objectives and reviewed the technology on which it would be
based. CMS 1997/104 explained some important design concepts on which CRISTAL
is and showed how CRISTAL integrated the domains of product data man- agement
and workflow management. This note explains, through the use of diagrams, how
CRISTAL can be established for detector production and used as the information
source for analyses, such as calibration and slow controls, carried out by
physicists. The reader should consult the earlier CMS Notes and conference
papers for technical detail on CRISTAL - this note concentrates on issues
surrounding the practical use of the CRISTAL software.


title: Dogmatism and Theoretical Pluralism in Modern Cosmology

abstract:
  This work discusses the presence of a dogmatic tendency within modern
cosmology, and some ideas capable of neutralizing its negative influence. It is
verified that warnings about the dangers of dogmatic thinking in cosmology can
be found as early as the 1930's, and we discuss the modern appearance of
"scientific dogmatism". The solution proposed to counteract such an influence,
which is capable of neutralizing this dogmatic tendency, has its origins in the
philosophical thinking of the Austrian physicist Ludwig Boltzmann (1844-1906).
In particular we use his two main epistemological theses, scientific theories
as representations of nature and theoretical pluralism, to show that once they
are embodied in the research practice of modern cosmology, there is no longer
any reason for dogmatic behaviours.


title:
Nonclassical Kinetics in Constrained Geometries: Initial Distribution
  Effects

abstract:
  We present a detailed study of the effects of the initial distribution on the
kinetic evolution of the irreversible reaction A+B -> 0 in one dimension. Our
analytic as well as numerical work is based on a reaction-diffusion model of
this reaction. We focus on the role of initial density fluctuations in the
creation of the macroscopic patterns that lead to the well-known kinetic
anomalies in this system. In particular, we discuss the role of the long
wavelength components of the initial fluctuations in determining the long-time
behavior of the system. We note that the frequently studied random initial
distribution is but one of a variety of possible distributions leading to
interesting anomalous behavior. Our discussion includes an initial distribution
with correlated A-B pairs and one in which the initial distribution forms a
fractal pattern. The former is an example of a distribution whose long
wavelength components are suppressed, while the latter exemplifies one whose
long wavelength components are enhanced, relative to those of the random
distribution.


title: Density Functional Theory -- an introduction

abstract:
  Density Functional Theory (DFT) is one of the most widely used methods for
"ab initio" calculations of the structure of atoms, molecules, crystals,
surfaces, and their interactions. Unfortunately, the customary introduction to
DFT is often considered too lengthy to be included in various curricula. An
alternative introduction to DFT is presented here, drawing on ideas which are
well-known from thermodynamics, especially the idea of switching between
different independent variables. The central theme of DFT, i.e. the notion that
it is possible and beneficial to replace the dependence on the external
potential v(r) by a dependence on the density distribution n(r), is presented
as a straightforward generalization of the familiar Legendre transform from the
chemical potential (\mu) to the number of particles (N). This approach is used
here to introduce the Hohenberg-Kohn energy functional and to obtain the
corresponding theorems, using classical nonuniform fluids as simple examples.
The energy functional for electronic systems is considered next, and the
Kohn-Sham equations are derived. The exchange-correlation part of this
functional is discussed, including both the local density approximation to it,
and its formally exact expression in terms of the exchange-correlation hole. A
very brief survey of various applications and extensions is included.

categories: physics.ed-ph cond-mat physics.chem-ph physics.comp-ph


title:
Energy calibration of the NaI(Tl) calorimeter of the SND detector using
  $e^+e^- \to e^+e^-$ events

abstract:
  Calibration of the three layer NaI(Tl) spherical calorimeter of the SND
detector using electron -- positron scattering events is described. Energy
resolution of $5 % (FWHM/2.36)$ for 500 MeV photons was achieved.


title: Nearly Closed Loops in Biological Systems as Electromagnetic Receptors

abstract:
  It is noted here that when a nearly closed loop in a biological system, such
as a self-synapsing (autapsing) neuron or mutually synapsing pair, is exposed
to an AC magnetic field, the induced electric fields in the insulating gaps can
be many orders of magnitude larger than the average values typically discussed
in the literature.$^{1,2}$ It is suggested that animal nervous systems might
possibly be affected in selected spots by man-made alternating magnetic fields
at weaker levels than previously supposed.
  Radio and microwave radiation should be considered particularly suspect.


title: Characteristic Temperatures of Folding of a Small Peptide

abstract:
  We perform a generalized-ensemble simulation of a small peptide taking the
interactions among all atoms into account. From this simulation we obtain
thermodynamic quantities over a wide range of temperatures. In particular, we
show that the folding of a small peptide is a multi-stage process associated
with two characteristic temperatures, the collapse temperature T_{\theta} and
the folding temperature T_f. Our results give supporting evidence for the
energy landscape picture and funnel concept. These ideas were previously
developed in the context of studies of simplified protein models, and here for
the first time checked in an all-atom Monte Carlo simulation.


title:
Tertiary structure prediction of C-peptide of ribonuclease A by
  multicanonical algorithm

abstract:
  We have performed multicanonical Monte Carlo simulations of C-peptide of
ribonuclease A. It is known by CD and NMR experiments that this peptide has
high alpha-helix content in aqueous solution and that the side-chain charges of
residues Glu-2$^-$ and His-12$^+$ play an important role in the stability of
the alpha-helix. In order to confirm these experimental implications, we have
used two analogues of the peptide with charged and neutral side chains of Glu-2
and His-12. Two dielectric functions, distance-dependent and constant, are
considered to study the effects of solvent contributions. All the simulations
were started from random initial conformations. Various thermodynamic
quantities such as average helicity as a function of residue number and average
distance between two side chains as a function of temperature are calculated.
The results are found to be in accord with the implications of CD and NMR
experiments. The lowest-energy conformation obtained has an alpha-helix from
Ala-4 to Gln-11 in complete agreement with the corresponding structure deduced
from an X-ray crystallography experiment of ribonuclease A. It is shown that
the salt bridge between the side chains of Glu-2$^-$ and Arg-10$^+$, which is
known to exist from both NMR and X-ray experiments, is formed only when the
side chains are properly charged. Its formation is greatly enhanced when the
distance-dependent dielectric function is used.


title:
Limit on suppression of ionization in metastable neon traps due to
  long-range anisotropy

abstract:
  This paper investigates the possibility of suppressing the ionization rate in
a magnetostatic trap of metastable neon atoms by spin-polarizing the atoms.
Suppression of the ionization is critical for the possibility of reaching
Bose-Einstein condensation with such atoms. We estimate the relevant long-range
interactions for the system, consisting of electric quadrupole-quadrupole and
dipole-induced dipole terms, and develop short-range potentials based on the
Na_2 singlet and triplet potentials. The auto-ionization widths of the system
are also calculated. With these ingredients we calculate the ionization rate
for spin-polarized and for spin-isotropic samples, caused by anisotropy of the
long-range interactions. We find that spin-polarization may allow for four
orders of magnitude suppression of the ionization rate for Ne. The results
depend sensitively on a precise knowledge of the interaction potentials,
however, pointing out the need for experimental input. The same model gives a
suppression ratio close to unity for metastable xenon in accordance with
experimental results, due to a much increased anisotropy in this case.


title: High resolution amplitude and phase gratings in atom optics

abstract:
  An atom-field geometry is chosen in which an atomic beam traverses a field
interaction zone consisting of three fields, one having frequency $\Omega
=c/\lambda $ propagating in the $\hat{z}$ direction and the other two having
frequencies $\Omega +\delta_{1}$ and $\Omega +\delta_{2}$ propagating in the
-$\hat{z}$ direction. For $n_{1}\delta_{1}+n_{2}\delta_{2}=0$ and $|\delta_{1}|
T,|\delta_{2}| T\gg 1$, where $n_{1}$ and $n_{2}$ are positive integers and $T$
is the pulse duration in the atomic rest frame, the atom-field interaction
results in the creation of atom amplitude and phase gratings having period $%
\lambda /[2(n_{1}+n_{2})]$. In this manner, one can use optical fields having
wavelength $\lambda $ to produce atom gratings having periodicity much less
than $\lambda $.


title: The structure of the atomic helium trimers: Halos and Efimov states

abstract:
  The Faddeev equations for the atomic helium-trimer systems are solved
numerically with high accuracy both for the most sophisticated realistic
potentials available and for simple phenomenological potentials. An efficient
numerical procedure is described. The large-distance asymptotic behavior,
crucial for weakly bound three-body systems, is described almost analytically
for arbitrary potentials. The Efimov effect is especially considered. The
geometric structures of the bound states are quantitatively investigated. The
accuracy of the schematic models and previous computations is comparable, i.e.
within 20% for the spatially extended states and within 40% for the smaller
^4He-trimer ground state.


title: Directional emission from asymmetric resonant cavities

abstract:
  Asymmetric resonant cavities (ARCs) with highly non-circular but convex
cross-sections are predicted theoretically to have high-Q whispering gallery
modes with very anisotropic emission. We develop a ray dynamics model for the
emission pattern and present numerical and experimental confirmation of the
theory.

categories: physics.optics chao-dyn nlin.CD physics.class-ph


title: Ionic structure and photoabsorption in medium sized sodium clusters

abstract:
  We present ground-state configurations and photoabsorption spectra of Na-7+,
Na-27+ and Na-41+. Both the ionic structure and the photoabsorption spectra of
medium-size sodium clusters beyond Na-20 have been calculated self-consistently
with a nonspherical treatment of the valence electrons in density functional
theory. We use a local pseudopotential that has been adjusted to experimental
bulk properties and the atomic 3s level of sodium. Our studies have shown that
both the ionic structure of the ground state and the positions of the plasmon
resonances depend sensitively on the pseudopotential used in the calculation,
which stresses the importance of its consistent use in both steps.


title: Molecular theories and simulation of ions and polar molecules in water

abstract:
  Recent developments in molecular theories and simulation of ions and polar
molecules in water are reviewed. The hydration of imidazole and imidazolium
solutes is used to exemplify the theoretical issues. The treatment of
long-ranged electrostatic interactions in simulations is discussed extensively.
It is argued that the Ewald approach is an easy way to get correct hydration
free energies in the thermodynamic limit from molecular calculations; and that
molecular simulations with Ewald interactions and periodic boundary conditions
can also be more efficient than many common alternatives. The Ewald treatment
permits a conclusive extrapolation to infinite system size. The picture that
emerges from testing of simple models is that the most prominent failings of
the simplest theories are associated with solvent proton conformations that
lead to non-gaussian fluctuations of electrostatic potentials. Thus, the most
favorable cases for the second-order perturbation theories are monoatomic
positive ions. For polar and anionic solutes, continuum or gaussian theories
are less accurate. The appreciation of the specific deficiencies of those
simple models have led to new concepts, multistate gaussian and quasi-chemical
theories, that address the cases for which the simpler theories fail. It is
argued that, relative to direct dielectric continuum treatments, the
quasi-chemical theories provide a better theoretical organization for the
computational study of the electronic structure of solution species.


title:
Non-adiabatic molecular Hamiltonian: Canonical transformation coupling
  electronic and vibrational motions

abstract:
  The coupling of electronic and vibrational motion is studied by two canonical
transformations namely normal coordinate transformation and momentum
transformation on molecular Hamiltonian. It is shown that by these
transformations we can pass from crude approximation to adiabatic approximation
and then to non-adiabatic (diabatic) Hamiltonian. This leads to renormalized
fermions and renormalized diabatic phonons. Simple calculations on $H_{2}$,
$HD$, and $D_{2}$ systems are performed and compared with previous approaches.
Problem of electronic quasi-degeneracy is discussed.


title:
Ab initio calculations of structures and stabilities of (NaI)_nNa+ and
  (CsI)_nCs+ cluster ions

abstract:
  Ab initio calculations using the Perturbed Ion model, with correlation
contributions included, are presented for nonstoichiometric (NaI)_nNa+ and
(CsI)_nCs+ (n=1-14) cluster ions. The ground state and several low-lying
isomers are identified and described. Rocksalt ground states are common and
appear at cluster sizes lower than in the corresponding neutral systems. The
most salient features of the measured mobilities seem to be explained by
arguments related to the changes of the compactness of the clusters as a
function of size. The stability of the cluster ions against evaporation of a
single alkali halide molecule shows variations that explain the enhanced
stabilities found experimentally for cluster sizes n=4, 6, 9, and 13. Finally,
the ionization energies and the orbital eigenvalue spectrum of two (NaI)_13Na+
isomers are calculated and shown to be a fingerprint of the structure.


title: The weak isospin and the gravity

abstract:
  The Clifford pentad of 4X4 complex matrices defines the currents of the
particles. The weak isospin transformation scatters the particle on two
components into the 2-dimensional space of the antidiagonal Clifford matrices.
The physics particles move in the 3-dimensional space of the diagonal Clifford
matrices. Such sectioning of the 5-dimensional space on two subspace
(2-dimensional and 3-dimensional) defines the Newtonian gravity principle.


title: A Cubic Micron of Equilibrium Pair Plasma?

abstract:
  Is it possible to create a small volume of equilibrium pair plasma in the
laboratory with an intense laser pulse? No. The required power would exceed
10^{18} W. The number of seed particles required to absorb the laser energy
would approach the number of pairs in the desired plasma, and their radiation
in a visible laser field would occur at extremely high frequencies.


title:
Investigation of renormalization group methods for the numerical
  simulation of isotropic turbulence

abstract:
  Renormalization group has enjoyed successes in other areas of statistical
physics. However, its application to turbulence faces several technical
difficulties, which have had to be circumvented by uncontrolled approximations.
Indeed, in view of the deterministic nature of the Navier-Stokes equations, it
is clear that the operation of averaging out the high-wavenumber modes while
keeping the low-wavenumber modes constant, cannot be done rigorously and in
itself can only be an approximation.
  With points like this in mind, we have recently adopted direct numerical
simulation as a tool for probing the basic feasibility of using RG techniques
to reduce the number of degrees of freedom requiring to be numerically
simulated. In this paper, we present some of the first results of this
approach.


title:
Explict-scales projections of the partitioned non-linear term in direct
  numerical simulation of the Navier-Stokes equation

abstract:
  In this paper we consider the properties of the internal partitions of the
nonlinear term, obtained when a filter with a sharp cutoff is introduced in
wavenumber space. We see what appears to be some degree of independence of the
choice of the position of the cutoff wavenumber for both instantaneous and
time-integrated partitioned nonlinearities. We also investigate the basic idea
of an eddy-viscosity model for subgrid terms and have found that while phase
modelling will be very poor, amplitude modelling can be far more successful.


title: The Geometry of Algorithms with Orthogonality Constraints

abstract:
  In this paper we develop new Newton and conjugate gradient algorithms on the
Grassmann and Stiefel manifolds. These manifolds represent the constraints that
arise in such areas as the symmetric eigenvalue problem, nonlinear eigenvalue
problems, electronic structures computations, and signal processing. In
addition to the new algorithms, we show how the geometrical framework gives
penetrating new insights allowing us to create, understand, and compare
algorithms. The theory proposed here provides a taxonomy for numerical linear
algebra algorithms that provide a top level mathematical view of previously
unrelated algorithms. It is our hope that developers of new algorithms and
perturbation theories will benefit from the theory, methods, and examples in
this paper.

categories: physics.comp-ph cond-mat math.NA physics.chem-ph


title:
Earthquake source parameters and fault kinematics in the Eastern
  California Shear Zone

abstract:
  Based on waveform data from a profile of aftershocks following the
north-south trace of the June 28, 1992 Landers rupture across the Mojave
desert, we construct a new velocity model for the Mojave region which features
a thin, slow crust. Using this model, we obtain source parameters, including
depth and duration, for each of the aftershocks in the profile, and in
addition, any significant (M>3.7) Joshua Tree--Landers aftershock between
April, 1992 and October, 1994 for which coherent TERRAscope data were
available. In all, we determine source parameters and stress-drops for 45
significant (M_w > 4) earthquakes associated with the Joshua Tree and Landers
sequences, using a waveform grid-search algorithm. Stress drops for these
earthquakes appear to vary systematically with location, with respect to
previous seismic activity, proximity to previous rupture (i.e., with respect to
the Landers rupture), and with tectonic province. In general, for areas north
of the Pinto Mountain fault, stress-drops of aftershocks located off the faults
involved with the Landers rupture are higher than those located on the fault,
with the exception of aftershocks on the newly recognized Kickapoo (Landers)
fault. Stress drops are moderate south of the Pinto Mountain fault, where there
is a history of seismic swarms but no single through-going fault. In contrast
to aftershocks in the eastern Transverse ranges, and related to the 1992 Big
Bear, California, sequence, Landers events show no clear relationship between
stress-drop and depth. Instead, higher stress-drop aftershocks appear to
correlate with activity on nascent faults, or those which experienced
relatively small slip during mainshock rupture.


title: Wavelet Analysis of Blood Pressure Waves in Vasovagal Syncope

abstract:
  We describe the multiresolution wavelet analysis of blood pressure waves in
vasovagal syncope affected patients compared with healthy people. We argue that
there exist discriminating criteria which allow us to isolate particular
features, common to the syncope-affected patients sample, indicating an
alternative diagnosis methodology for this syndrome. We perform a throughout
analysis both in the Haar basis and in a Gaussian one, with an attempt to grasp
the underlying dynamics.


title: Growth Models And The Question Of Universality Classes

abstract:
  In the past many papers have appeared which simulated surface growth with
different growth models. The results showed that, if models differed only
slightly in their `growth' rules, the resulting surfaces may belong to
different universality classes, i.e. they are described by different
differential equations. In the present paper we describe a mapping of ``growth
rules'' to differential operators and give plausibility arguments for this
mapping. We illustrate the validity of our theory by applying it to published
results.


title:
The Hopgrid algorithm: multilevel synthesis of multigrid and wavelet
  theory

abstract:
  The multigrid algorithm is a multilevel approach to accelerate the numerical
solution of discretized differential equations in physical problems involving
long-range interactions. Multiresolution analysis of wavelet theory provides an
efficient representation of functions which exhibit localized bursts of short
length-scale behavior. Applications such as computing the electrostatic field
in and around a molecule should benefit from both approaches. In this work, we
demonstrate how a novel interpolating wavelet transform, which in itself is the
synthesis of finite element analysis and wavelet theory, may be used as the
mathematical bridge to connect the two approaches. The result is a specialized
multigrid algorithm which may be applied to problems expressed in wavelet
bases. With this approach, interpolation and restriction operators and grids
for the multigrid algorithm are predetermined by an interpolating
multiresolution analysis. We will present the new method and contrast its
efficiency with standard wavelet and multigrid approaches.


title: Construction of Simulation Wavefunctions for Aqueous Species: D3O+

abstract:
  This paper investigates Monte Carlo techniques for construction of compact
wavefunctions for the internal atomic motion of the D3O+ ion. The polarization
force field models of Stillinger, et al and of Ojamae, et al. were used.
Initial pair product wavefunctions were obtained from the asymptotic high
temperature many-body density matrix after contraction to atom pairs using
Metropolis Monte Carlo. Subsequent characterization shows these pair product
wavefunctions to be well optimized for atom pair correlations despite that fact
that the predicted zero point energies are too high. The pair product
wavefunctions are suitable to use within variational Monte Carlo, including
excited states, and density matrix Monte Carlo calculations. Together with the
pair product wavefunctions, the traditional variational theorem permits
identification of wavefunction features with significant potential for further
optimization. The most important explicit correlation variable found for the
D3O+ ion was the vector triple product {\bf r}$_{OD1}\cdot$({\bf
r}$_{OD2}\times${\bf r}$_{OD3}$). Variational Monte Carlo with 9 of such
explicitly correlated functions yielded a ground state wavefunction with an
error of 5-6% in the zero point energy.


title:
Theories of Hydrophobic Effects and the Description of Free Volume in
  Complex Liquids

abstract:
  Recent progress on molecular theories of hydration of nonpolar solutes in
aqueous solution has led to new ways of thinking about the old issue of free,
or "available," volume in liquids. This article surveys the principal new
results with particular attention to general issues of packing in liquids.


title: Aberration and Special Relativity

abstract:
  Section 7 of Einstein's 1905 electrodynamics paper gives frequency-shift and
aberration formulae that together describe an elongated ellipsoidal wavefront.
A Lorentz contraction of this ellipsoid solves most (but not all) of the
associated relativistic problems.


title:
Pressure Calculation in Polar and Charged Systems using Ewald Summation:
  Results for the Extended Simple Point Charge Model of Water

abstract:
  Ewald summation and physically equivalent methods such as particle-mesh
Ewald, kubic-harmonic expansions, or Lekner sums are commonly used to calculate
long-range electrostatic interactions in computer simulations of polar and
charged substances. The calculation of pressures in such systems is
investigated. We find that the virial and thermodynamic pressures differ
because of the explicit volume dependence of the effective, resummed Ewald
potential. The thermodynamic pressure, obtained from the volume derivative of
the Helmholtz free energy, can be expressed easily for both ionic and rigid
molecular systems. For a system of rigid molecules, the electrostatic energy
and the forces at the atom positions are required, both of which are readily
available in molecular dynamics codes. We then calculate the virial and
thermodynamic pressures for the extended simple point charge (SPC/E) water
model at standard conditions. We find that the thermodynamic pressure exhibits
considerably less system size dependence than the virial pressure. From an
analysis of the cross correlation between the virial and thermodynamic
pressure, we conclude that the thermodynamic pressure should be used to drive
volume fluctuations in constant-pressure simulations.

categories: physics.chem-ph cond-mat.soft cond-mat.stat-mech physics.comp-ph


title: Volume free electron lasers

abstract:
  The equations describing the VFEL lasing in case of an electron beam moving
either in a split of a diffraction grating or in a vacuum waveguide containing
a diffraction grating (vacuum VFEL) have been obtained. The dispersion equation
allowing to find the vacuum VFEL gain in one-mode generation regime have been
considered. It is shown that the vacuum VFEL amplification and the generation
process develop more intensively then in ordinary FEL using one-dimensional
distributed feedback. Such the VFEL, if realised, could be made with much more
compact device structure compared with the FEL and therefore, may be
interesting for applications in different wavelength ranges: from submillimeter
to X-ray. Such the VFEL can be realised on the basis of the existing
accelerators.


title: Hydrogen and Helium Atoms and Molecules in an Intense Magnetic Field

abstract:
  We calculate the atomic structure of hydrogen and helium, atoms and molecules
in an intense magnetic field, analytically and numerically with a judiciously
chosen basis.


title:
An Automatic Method for Determination of Lg Arrival Times Using Wavelet
  Transforms

abstract:
  The regional phase Lg is used to estimate location and magnitude for sources
closer than 1500 km. The complexity of Lg waveforms makes it difficult to
consistently determine Lg arrival time, thus affecting source location with a
single station or array. This study tests an automatic method for timing Lg
arrivals using wavelet transforms to decompose the Lg signal into its
components localized both in time and scale. A Continuous Wavelet Transform
(CWT) using a Daubechies order two (db2) wavelet is applied to 10 seconds of
raw data, containing the start of Lg. Initial positioning of the window is
obtained using the standard Lg travel time tables. The coefficients at scale 8
from the db2 decomposition are squared and the resulting time series is
represented by an approximation of the 4'th level Discrete Wavelet Transform
(DWT) using a Haar wavelet. A threshold detector is then applied to the
resulting time series to determine the Lg arrival time. The method was tested
using well located earthquakes (USGS) and explosions from known mines (mb less
than 4.0), recorded on the vertical components at TXAR (Lajitas, Texas) and
PDAR (Pinedale, Wyoming) arrays. The Lg arrival time was automatically picked
with a standard deviation of less than 1.5 seconds (less than 10 km location
error) for well known locations. Location errors are larger with the increase
in distance and smaller with the increase in signal to noise ratio of events.


title:
Testrun results from prototype fiber detectors for high rate particle
  tracking

abstract:
  A fiber detector concept has been realized allowing to registrate particles
within less than 100 nsec with a space point precision of about 0.1 mm at low
occupancy. Three full size prototypes have been build by different producers
and tested at a 3 GeV electron beam at DESY. After 3 m of light guides 8-10
photoelectrons were registrated by multichannel photomultipliers providing an
efficiency of more than 99%. Using all available data a resolution of 0.086 mm
was measured.


title:
Nonlinear phase shift without cascaded second-order processes and third
  order nonlinearity

abstract:
  The new mechanism for obtaining a nonlinear phase shift has been proposed and
the schemes are described for its implementation. As it is shown, the
interference of two waves with intensity-dependent amplitude ratio coming from
the second harmonic generation should produce the nonlinear phase shift. The
sign and amount of nonlinear distortion of a beam wavefront is dependent of the
relative phase of the waves that is introduced by the phase element. Calculated
value of $n_2^{eff}$ exceeds that connected with cascaded quadratic
nonlinearity, at the same conditions.


title: World Wide Student Laboratory. Description of Project

abstract:
  This paper describes a new framework in educational technology - the World
Wide Student Laboratory (WWSL) Project. WWSL is a dynamic international
Internet-based collaboration of resourses of educational and research labs of
universities, institutions, government research centers and companies. The
concepts of the WWSL are outlined, a possible idea for structure is discussed
and examples of various WWSL studies are shown.


title:
Finite-Difference Implementation of Inviscid Separated Flows with
  Infinitely-Long Cusp-Ended Stagnation Zone around Circular Cylinder

abstract:
  The classical Helmholtz problem is applied for modelling and numerical
investigation of inviscid cusp-ended separated flow around circular cylinder.
Two coordinate systems are used: polar for initial calculations and parabolic
as topologically most suited for infinite stagnation zone. Scaling by the shape
of the unknown free line renders the problem to computational domain with fixed
boundaries. Difference schemes and algorithm for Laplace equation and for
Bernoulli integral are devised. A separated flow with drag coefficient $C_x=0$
like the so called ``critical'' flow is obtained. The pressure distribution on
the surface of cylinder and the detachment point compares quantitatively very
well with the predictions of the hodograph method.


title: Statistics of Certain Models of Evolution

abstract:
  In a recent paper, Newman surveys the literature on power law spectra in
evolution, self-organised criticality and presents a model of his own to arrive
at a conclusion that self-organised criticality is not necessary for evolution.
Not only did he miss a key model (Ecolab) that has a clear self-organised
critical mechanism, but also Newman's model exhibits the same mechanism that
gives rise to power law behaviour as does Ecolab. Newman's model is, in fact, a
``mean field'' approximation of a self-organised critical system. In this
paper, I have also implemented Newman's model using the Ecolab software,
removing the restriction that the number of species remains constant. It turns
out that the requirement of constant species number is non-trivial, leading to
a global coupling between species that is similar in effect to the species
interactions seen in Ecolab. In fact, the model must self-organise to a state
where the long time average of speciations balances that of the extinctions,
otherwise the system either collapses or explodes. In view of this, Newman's
model does not provide the hoped-for counter example to the presence of
self-organised criticality in evolution, but does provide a simple, almost
analytic model that can used to understand more intricate models such as
Ecolab.


title:
Turbulent Decay of a Passive Scalar in Batchelor Limit: Exact Results
  from a Quantum-Mechanical Approach

abstract:
  We show that the decay of a passive scalar $\theta$ advected by a random
incompressible flow with zero correlation time in Batchelor limit can be mapped
exactly to a certain quantum-mechanical system with a finite number of degrees
of freedom. The Schroedinger equation is derived and its solution is analyzed
for the case when at the beginning the scalar has Gaussian statistics with
correlation function of the form $e^{-|x-y|^2}$. Any equal-time correlation
function of the scalar can be expressed via the solution to the Schroedinger
equation in a closed algebraic form. We find that the scalar is intermittent
during its decay and the average of $|\theta|^\alpha$ (assuming zero mean value
of $\theta$) falls as $e^{-\gamma_\alpha Dt}$ at large $t$, where $D$ is a
parameter of the flow, $\gamma_\alpha=\alpha(6-\alpha)/4$ for $0<\alpha<3$, and
$\gamma_\alpha=9/4$ for $\alpha \geq 3$, independent of $\alpha$.

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


title:
Kinetics properties of voltage induced colicin Ia channels into a lipid
  bilayer

abstract:
  The activation kinetics of the ion channels formed by colicin Ia incorporated
into a planar bilayer lipid membrane (BLM) was investigated by the voltage
clamp technique using different step voltage stimuli. The temporal behaviour of
ion channels put in evidence a gain or a loss of memory, revealed by a specific
sequence of electrical pulses used for stimulation.


title:
First experiments with a 100 period superconductive undulator with a
  period length of 3.8 mm

abstract:
  A prototype of a novel superconductive undulator with a period length of 3.8
mm is described. The undulator is 100 periods long. In the first tests
described in this paper the undulator was cooled in a helium bath and it was
shown that it can be operated as expected with a maximum current of 1400 A.
Afterwards the undulator field was measured with a miniature Hall probe with an
active area of (100x100)x10^-6 m^2. Calculated and measured field distributions
are in good agreement. A cryostat for a beam test at Mainz microtron MAMI was
built in which liquid helium cools indirectly the in-vacuum undulator. At the
moment the cryostat is tested and optimized.


title: Hydrophobic Effects on a Molecular Scale

abstract:
  A theoretical approach is developed to quantify hydrophobic hydration and
interactions on a molecular scale, with the goal of gaining insight into the
molecular origins of hydrophobic effects. The model is based on the fundamental
relation between the probability for cavity formation in bulk water resulting
from molecular-scale density fluctuations, and the hydration free energy of the
simplest hydrophobic solute, a hard particle. This probability is estimated
using an information theory (IT) approach, incorporating experimentally
available properties of bulk water -- the density and radial distribution
function. The IT approach reproduces the simplest hydrophobic effects:
hydration of spherical nonpolar solutes, the potential of mean force between
methane molecules, and solvent contributions to the torsional equilibrium of
butane. Applications of this approach to study temperature and pressure effects
provide new insights into the thermodynamics and kinetics of protein folding.
The IT model relates the hydrophobic-entropy convergence observed in protein
unfolding experiments to the macroscopic isothermal compressibility of water. A
novel explanation for pressure denaturation of proteins follows from an
analysis of the pressure stability of hydrophobic aggregates, suggesting that
water penetrates the hydrophobic core of proteins at high pressures. This
resolves a long-standing puzzle, whether pressure denaturation contradicts the
hydrophobic-core model of protein stability. Finally, issues of ``dewetting''
of molecularly large nonpolar solutes are discussed in the context of a
recently developed perturbation theory approach.


title: Super Shell Structure of the Magnetic Susceptibility

abstract:
  The magnetic susceptibility of electrons confined to a spherical cavity or a
circular billiard shows slow oscillations as a function of the number of
electrons, which are a new manifestation of the Super Shell Structure found in
the free energy of metal clusters. The relationship of the oscillations of the
two different quantities is analyzed by means of semiclassical calculations,
which are in quantitative agreement with quantal results.


title:
Some Numerical Experiments on Round-off Error Growth in Finite Precision
  Numerical Computation

abstract:
  Finite precision computations using digital computers involve the following
inherent errors: (1) Round-off error of finite precision computations (2)
Binary computer arithmetic precludes exact number representation of traditional
decimal system used in data input stage to the computer. Though the round-off
error is as small as in the seventh decimal place (single precision) in the
beginning, it can enter the mainstream computation within 50 iterations in
iterative computations, such as that used in numerical integration schemes, for
example, the commonly used fourth order Runge-Kutta method. Growth of round-off
error in recursive vis-a-vis iterative computing is described in the text. In
this paper several computational experiments are presented to demonstrate the
rapid growth of round-off error in iterative computations.


title:
Comment on "Statistical Mechanics of Membrane-Protein Conformation: A
  Homopolymer Model"

abstract:
  Some aspects of a recent paper about protein-membrane interaction are
inadequate due to lack of structural information.


title: Equation of state of a strongly magnetized hydrogen plasma

abstract:
  The influence of a constant uniform magnetic field on the thermodynamic
properties of a partially ionized hydrogen plasma is studied. Using the method
of Green' s function various interaction contributions to the thermodynamic
functions are calculated. The equation of state of a quantum magnetized plasma
is presented within the framework of a low density expansion up to the order
e^4 n^2 and, additionally, including ladder type contributions via the bound
states in the case of strong magnetic fields (2.35*10^{5} T << B << 2.35*10^{9}
T). We show that for high densities (n=10^{27-30} m^{-3}) and temperatures
T=10^5 - 10^6 K typical for the surface of neutron stars nonideality effects
as, e.g., Debye screening must be taken into account.


title: Muon Collider Overview: Progress and Future Plans

abstract:
  Besides continued work on the parameters of a 3-4 and 0.5 TeV CoM collider,
many studies are now concentrating on a machine near 100 GeV that could be a
factory for the s-channel production of Higgs particles. We mention the
research on the various components in such muon colliders, starting from the
proton accelerator needed to generate pions from a heavy-Z target and
proceeding through the phase rotation and decay channel, muon cooling,
acceleration, storage in a ring and the collider detector. We also mention
theoretical and experimental R&D plans for the next several years that should
lead to a better understanding of the design and feasibility issues for all of
the components. This note is a summary of a report updating the progress on the
R&D since the Feasibility Study of Muon Colliders presented at the Workshop
Snowmass'96.


title:
Lossless Tapers, Gaussian Beams, Free-Space Modes: Standing Waves Versus
  Through-Flowing Waves

abstract:
  It was noticed in the past that, to avoid physical inconsistencies, in
Marcatili's lossless tapers through-flowing waves must be drastically different
from standing waves. First, we reconfirm this by means of numerical results
based on an extended BPM algorithm. Next, we show that this apparently
surprising behavior is a straightforward fallout of Maxwell's equations. Very
similar remarks apply to Gaussian beams in a homogeneous medium. As a
consequence, Gaussian beams are shown to carry reactive powers, and their
active power distributions depart slightly from their standard pictures.
Similar conclusions hold for free-space modes expressed in terms of Bessel
functions.


title: Active Stark Atomic Spectroscopy

abstract:
  Active Stark Atomic Spectroscopy (ASAS) method can be used to determine a
high electric field in the diode of an ion or electron accelerator as a
function of position and time, including the positions of anode and cathode
plasma emission surfaces (in order to obtain the effective accelerating gap).
As possible probe beams, we suggest the use of lithium and sodium atoms. The
diagnostic provides a means to measure diode quantities spectroscopically with
excellent spatial resolution.


title: Is Science going through a critical stage?

abstract:
  The unexpected discoveries at the beginning of the century, particularly
thanks to Heisenberg, Bohr, and Godel, has driven the science to drastic
changes, opening new, extraordinary, and infinite research fields. After this,
many scientists saw, and still today see, a crisis, with dreadful meaning, in
the science. However, this crisis is only present in that type of science,
driven by determinism, which is strictly linked to the common sense.


title: Kinetic theoretical foundation of Lorentzian statistical mechanics

abstract:
  A new kinetic theory Boltzmann-like collision term including correlations is
proposed. In equilibrium it yields the one-particle distribution function in
the form of a generalised-Lorentzian resembling but not being identical with
the so-called $\kappa$ distribution frequently found in collisionless turbulent
systems like space plasmas. We show that this distribution function satisfies a
generalised $H$-theorem, yields an expression for the entropy that is concave.
Thus, the distribution is a `true' thermodynamic equilibrium distribution,
presumably valid for turbulent systems. In equilibrium it is possible to
construct the fundamental thermodynamic quantities. This is done for an ideal
gas only. The new kinetic equation can form the basis for obtaining a set of
hydrodynamic conservation laws and construction of a generalised transport
theory for strongly correlated states of a system.


title:
Quantum Maxwell-Bloch equations for spatially inhomogeneous
  semiconductor lasers

abstract:
  We present quantum Maxwell-Bloch equations (QMBE) for spatially inhomogeneous
semiconductor laser devices. The QMBE are derived from fully quantum mechanical
operator dynamics describing the interaction of the light field with the
quantum states of the electrons and the holes near the band gap. By taking into
account field-field correlations and field-dipole correlations, the QMBE
include quantum noise effects which cause spontaneous emission and amplified
spontaneous emission. In particular, the source of spontaneous emission is
obtained by factorizing the dipole-dipole correlations into a product of
electron and hole densities. The QMBE are formulated for general devices, for
edge emitting lasers and for vertical cavity surface emitting lasers, providing
a starting point for the detailed analysis of spatial coherence in the near
field and far field patterns of such laser diodes. Analytical expressions are
given for the spectra of gain and spontaneous emission described by the QMBE.
These results are applied to the case of a broad area laser, for which the
frequency and carrier density dependent spontaneous emission factor beta and
the evolution of the far field pattern near threshold are derived.

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


title: Louis de Broglie und die Quantenmechanik

abstract:
  In 1923 Louis de Broglie (1892-1987) discovered the material waves and six
years later received the Nobel price for this discovery. Apart these well known
facts this French physicist nevertheless seems to be forgotten. Details of his
life are as unknown as his efforts to describe quantum mechanics in a
deterministic and objective way. Especially the actual discussion concerning
the interpretation of quantum mechanics seems to justify a deeper occupation
with the scientific work of Louis de Broglie. In this context the important
influence of Albert Einstein is of special interest; for his photons announce
the existence of material waves and it may surprise that Einstein himself did
not postulate them. The basis of this short scientific biography are the
publications of de Broglie (a complete bibliography is given at the end), some
more or less short memories of his students and some unpublished documents
found in the "Archives de l'Academie des Sciences" at Paris. The original text
of the correspondence between de Broglie and Einstein is enclosed in German
translation in the appendix.

categories: physics.hist-ph physics.ed-ph physics.pop-ph physics.soc-ph quant-ph


title: Speculations on the Neutrino Theory of Light

abstract:
  The basis of new ideas in the old theory is the Majorana and Ahluwalia
constructs, modified versions of the Weinberg $2(2j+1)$ theory, and the Barut's
self-field quantum electrodynamics.


title: Full-vector analysis of a realistic photonic crystal fiber

abstract:
  We analyze the guiding problem in a realistic photonic crystal fiber using a
novel full-vector modal technique, a biorthogonal modal method based on the
nonselfadjoint character of the electromagnetic propagation in a fiber.
Dispersion curves of guided modes for different fiber structural parameters are
calculated along with the 2D transverse intensity distribution of the
fundamental mode. Our results match those achieved in recent experiments, where
the feasibility of this type of fiber was shown.


title: Ruler-changes and Relative Velocity

abstract:
  Simple signal-propagation effects make receding objects seem contracted and
approaching objects seem elongated. These effects are theoretically
photographable, and are proportional in strength to the frequency-change in the
object's emitted light. In a one-dimensional version of the "barn-pole"
experiment, a "moving" object's photographed image can appear doubly
length-dilated according to fixed-aether theory, but only singly length-dilated
according to SR. This expected difference might be charitably described as a
form of photographable Lorentz contraction.


title: Superluminality and Pair-Production

abstract:
  When an information-carrying lightbeam is (legally) swept across a surface at
more than c, simple signal-propagation arguments allow the observed behavior of
the moving image (or "sprite") to include time-reversal and pair-production
effects. A pair-production description also arises if we try to impose some
common assumptions of general relativity onto the physics of an
indirectly-radiating Eighteenth-Century "dark star". This result seems
suspiciously similar to the modern concept of "Hawking radiation".


title: Numerical Evidence for Divergent Burnett Coefficients

abstract:
  In previous papers [Phys. Rev. A {\bf 41}, 4501 (1990), Phys. Rev. E {\bf
18}, 3178 (1993)], simple equilibrium expressions were obtained for nonlinear
Burnett coefficients. A preliminary calculation of a 32 particle Lennard-Jones
fluid was presented in the previous paper. Now, sufficient resources have
become available to address the question of whether nonlinear Burnett
coefficients are finite for soft spheres. The hard sphere case is known to have
infinite nonlinear Burnett coefficients (ie a nonanalytic constitutive
relation) from mode coupling theory. This paper reports a molecular dynamics
caclulation of the third order nonlinear Burnett coefficient of a Lennard-Jones
fluid undergoing colour flow, which indicates that this term is diverges in the
thermodynamic limit.


title:
On the determination of probability density functions by using Neural
  Networks

abstract:
  It is well known that the output of a Neural Network trained to disentangle
between two classes has a probabilistic interpretation in terms of the
a-posteriori Bayesian probability, provided that a unary representation is
taken for the output patterns. This fact is used to make Neural Networks
approximate probability density functions from examples in an unbinned way,
giving a better performace than ``standard binned procedures''. In addition,
the mapped p.d.f. has an analytical expression.


title: The Quantum Mechanical Current of the Pauli Equation

abstract:
  We argue that the process of constructing the quantum mechanical current of
the Pauli equation by copying the line of arguments used in the spin-0 case,
i.e. the Schr\"{o}dinger equation, is ambiguous. We show that a
non-relativistic reduction of the relativistic Dirac four-vector current is,
however, capable of fully resolving the problem. This analysis reveals that the
non-relativistic current of the Pauli equation should include an extra term of
the form $\vec \nabla \vec \times (\psi^{\dagger} \vec \sigma \psi)$. We
present an initial exploration of the potential consequences of this new
'spin-term' by solving the Pauli equation for crossed magnetic and electric
fields and calculating the corresponding current.


title: Stable Elliptical Vortices in a Cylindrical Geometry

abstract:
  We show that, in a two-dimensional (2d) ideal fluid (also applies to a column
of quasi-2d non-neutral plasma in an axial magnetic field), large elliptical
vortices in a finite disk are stable. The stability is established by
comparison between energy of elliptical and symmetrical states to satisfy a
sufficient condition, without dynamical eigen-analysis. Analytical small
ellipticity expansion of energy and exact numerical values for finite
ellipticity are both obtained. The expansion indicates stable linear l=2
diocotron modes for large vortices (or plasma columns). Numerical simulations
of the 2d Euler equation are also performed. They not only confirm the
sufficient condition, but also show that the stability persists to smaller
vortex sizes. The reason why decaying l=2 modes were obtained by Briggs,
Daugherty, and Levy [Phys. Fluids 13, 421 (1970)] using eigen-analysis is also
discussed.


title:
Collimated electron jets by intense laser beam-plasma surface
  interaction under oblique incidence

abstract:
  Oblique incidence of a $p$-polarized laser beam on a fully ionized plasma
with a low density plasma corona is investigated numerically by
Particle-In-Cell and Vlasov simulations in two dimensions. A single narrow
self-focused current jet of energetic electrons is observed to be projected
into the corona nearly normal to the target. Magnetic fields enhance the
penetration depth of the electrons into the corona. A scaling law for the angle
of the ejected electrons with incident laser intensity is given.


title: Beam Instabilities in Magnetized Pair Plasma

abstract:
  Beam instabilities in the strongly magnetized electron-positron plasma of
pulsar magnetospheres are considered. We analyze the resonance conditions and
estimate the growth rates of the Cherenkov and cyclotron instabilities of the
ordinary (O), extraordinary (X) and Alfv\'{e}n modes in two limiting regimes:
kinetic and hydrodynamic. As a preliminary step, we reconsider wave dispersion
and polarization properties in a one dimensional pair plasma taking into
account relativistic thermal effects. We then find the location of the
Cherenkov and cyclotron resonance of the X, O and Alfv\'{e}n waves with the
particles from the primary beam. The importance of the different instabilities
as a source of the coherent pulsar radiation generation is then estimated
taking into account the angular dependence of the growth rates and the
limitations on the length of the coherent wave-particle interaction imposed by
the curvature of the magnetic field lines. We conclude, that in the pulsar
magnetosphere the Cherenkov-type instabilities occur in the hydrodynamic
regimes, while the cyclotron-type instabilities occur in the kinetic regime. We
argue, that electromagnetic cyclotron-type instabilities on the X, O and
probably Alfv\'{e}n waves are more likely to develop in the pulsar
magnetosphere.


title:
Advances in the proposed electromagnetic zero-point field theory of
  inertia

abstract:
  A NASA-funded research effort has been underway at the Lockheed Martin
Advanced Technology Center in Palo Alto and at California State University in
Long Beach to develop and test a recently published theory that Newton's
equation of motion can be derived from Maxwell's equations of electrodynamics
as applied to the zero-point field (ZPF) of the quantum vacuum. In this
ZPF-inertia theory, mass is postulated to be not an intrinsic property of
matter but rather a kind of electromagnetic drag force that proves to be
acceleration dependent by virtue of the spectral characteristics of the ZPF.
The theory proposes that interactions between the ZPF and matter take place at
the level of quarks and electrons, hence would account for the mass of a
composite neutral particle such as the neutron. An effort to generalize the
exploratory study of Haisch, Rueda and Puthoff (1994) into a proper
relativistic formulation has been successful. Moreover the principle of
equivalence implies that in this view gravitation would also be electromagnetic
in origin along the lines proposed by Sakharov (1968). With regard to exotic
propulsion we can definitively rule out one speculatively hypothesized
mechanism: matter possessing negative inertial mass, a concept originated by
Bondi (1957) is shown to be logically impossible. On the other hand, the linked
ZPF-inertia and ZPF-gravity concepts open the conceptual possibility of
manipulation of inertia and gravitation, since both are postulated to be
electromagnetic phenomena. It is hoped that this will someday translate into
actual technological potential. A key question is whether the proposed
ZPF-matter interactions generating the phenomenon of mass might involve one or
more resonances. This is presently under investigation.


title: Stopping of Charged Particles in a Magnetized Classical Plasma

abstract:
  The analytical and numerical investigations of the energy loss rate of the
test particle in a magnetized electron plasma are developed on the basis of the
Vlasov-Poisson equations, and the main results are presented. The Larmor
rotation of a test particle in a magnetic field is taken into account. The
analysis is based on the assumption that the energy variation of the test
particle is much less than its kinetic energy. The obtained general expression
for stopping power is analyzed for three cases: (i) the particle moves through
a collisionless plasma in a strong homogeneous magnetic field; (ii) the fast
particle moves through a magnetized collisionless plasma along the magnetic
field; and (iii) the particle moves through a magnetized collisional plasma
across a magnetic field. Calculations are carried out for the arbitrary test
particle velocities in the first case, and for fast particles in the second and
third cases. It is shown that the rate at which a fast test particle loses
energy while moving across a magnetic field may be much higher than the loss in
the case of motion through plasma without magnetic field.


title: Newton's law of inertia and time

abstract:
  A closer look (with hindsight) at Newtonian and relativistic kinematics
reveals two things. Not surprisingly, Newtonian time remains the empty and
artificial - albeit useful - figment it is known to be. Quite unexpectedly
however it turns out that with an only slightly more physical time-concept,
time and space remain separate entities and simultaneity of events becomes a
meaningful concept even for physicists.


title:
A PIM-aided Kalman Filter for GPS Tomography of the Ionospheric Electron
  Content

abstract:
  We develop the formalism for a PIM-based functional for stochastic tomography
with a Kalman filter, in which the inversion problem associated with
four-dimensional ionospheric stochastic tomography is regularized. For
consistency, GPS data is used to select dynamically the best PIM parameters, in
a 3DVAR fashion. We demonstrate the ingestion of GPS (IGS and GPS/MET) data
into a parameterized ionospheric model, used to select the set of parameters
that minimize a suitable cost functional. The resulting PIM-fitted model is
compared to direct 3D voxel tomography. We demonstrate the value of this method
analyzing IGS and GPS/MET GPS data, and present our results in terms of a 4D
model of the ionospheric electronic density.


title: Interacting Fermi gas in a Harmonic Trap

abstract:
  In view of ongoing experiments to trap ultracold spin-polarized $^6$Li, we
study various properties of an interacting Fermi gas in a harmonic trap taking
the discrete nature of the unperturbed harmonic trap levels into account
exactly. As $^6$Li has a rather large and negative scattering length, we focus
on the effects of the attractive atom-atom interaction on several thermodynamic
properties and on the momentum and density distributions.
  The dependence of the chemical potential, the specific heat and the density
and momentum distributions on the number of particles in the trap is obtained.
We also calculate the energy of the gas. Comparison is made with results of a
semiclassical calculation and with the properties of a non-interacting gas. We
find that the effect of the interactions is rather large for realistic trap
frequencies. Hence, it is important to include these interactions in any
quantitative predictions relevant for experiments.


title: Wake Field Effect Analysis in APT Linac

abstract:
  The 1.7-GeV 100-mA CW proton linac is now under design for the Accelerator
Production of Tritium (APT) Project. The APT linac comprises both the normal
conducting (below 211 MeV) and superconducting (SC) sections. The high current
leads to stringent restrictions on allowable beam losses (<1 nA/m), that
requires analyzing carefully all possible loss sources. While wake-field
effects are usually considered negligible in proton linacs, we study these
effects for the APT to exclude potential problems at such a high current. Loss
factors and resonance frequency spectra of various discontinuities of the
vacuum chamber are investigated, both analytically and using 2-D and 3-D
simulation codes with a single bunch as well as with many bunches. Our main
conclusion is that the only noticeable effect is the HOM heating of the 5-cell
SC cavities. It, however, has an acceptable level and, in addition, will be
taken care of by HOM couplers.


title: Cavity Loss Factors For Non-Ultrarelativistic Beams

abstract:
  Cavity loss factors can be easily computed for ultrarelativistic beams using
time-domain codes like MAFIA or ABCI. However, for non-ultrarelativistic beams
the problem is more complicated because of difficulties with its numerical
formulation in the time domain. We calculate the loss factors of a
non-ultrarelativistic bunch and compare results with the relativistic case.


title:
Halo Formation in Spheroidal Bunches with Self-Consistent Stationary
  Distributions

abstract:
  A new class of self-consistent 6-D phase space stationary distributions is
constructed both analytically and numerically. The beam is then mismatched
longitudinally and/or transversely, and we explore the beam stability and halo
formation for the case of 3-D axisymmetric beam bunches using particle-in-cell
simulations. We concentrate on beams with bunch length-to-width ratios varying
from 1 to 5, which covers the typical range of the APT linac parameters. We
find that the longitudinal halo forms first for comparable longitudinal and
transverse mismatches. An interesting coupling phenomenon - a longitudinal or
transverse halo is observed even for very small mismatches if the mismatch in
the other plane is large - is discovered.


title:
Application of numerical methods to modeling the stellar wind and
  interstellar medium interaction

abstract:
  We present a review of the application of numerical methods to solve the
problem of the stellar/solar wind with the local interstellar medium. Most of
approaches described are developed by the authors. They include both purely gas
dynamic and magnetohydrodynamic methods. Some attention is given to the
influence of the neutral component of the interstellar medium on the flow
structure. Far-field boundary conditions are formulated which are usually
required in astrophyscal application owing to the extremely large length scale
of these problems. Results are presented of the stationary and nonstationary,
axisymmetric and geniunly three-dimensional calculations. Newly developed
high-resolution numerical methods are discussed which can be applied to a large
variety of astrophysical problems. The bibliography includes 113 references.
The review will be published in ``CFD Review 97'' by John Wiley.


title:
A Gauge-invariant Hamiltonian Description of the Motion of Charged Test
  Particles

abstract:
  New, gauge-independent, second-order Lagrangian for the motion of classical,
charged test particles is used to derive the corresponding Hamiltonian
formulation. For this purpose a Hamiltonian description of the theories derived
from the second-order Lagrangian is presented. Unlike in the standard approach,
the canonical momenta arising here are explicitely gauge-invariant and have a
clear physical intepretation. The reduced symplectic form is equaivalent to the
Souriau's form. This approach illustrates a new method of deriving equations of
motion from field equations.


title:
Numerical simulation of gliding reflection of X-ray beam from rough
  surface

abstract:
  A new method for investigation of x-ray propagation in a rough narrow
dielectric waveguide is proposed on the basis of the numerical integration of
the quazioptical equation. In calculations a model rough surface was used with
the given statistical properties. It was shown that the losses in the narrow
waveguides strongly depend on the wall roughness and on the input angle. The
losses are not zero even at zero input angle if the width of the waveguide is
smaller or about 1 mkm. The effect is accounted for as the influence of
diffraction. The angular spread of the transmitted X-ray radiation is much more
narrow than the Fresnel angle of the total external reflection.


title: Sliding Blocks Revisited: A simulational Study

abstract:
  A computational study of sliding blocks on inclined surfaces is presented.
Assuming that the friction coefficient $\mu$ is a function of position, the
probability $P(\lambda)$ for the block to slide down over a length $\lambda$ is
numerically calculated. Our results are consistent with recent experimental
data suggesting a power-law distribution of events over a wide range of
displacements when the chute angle is close to the critical one, and suggest
that the variation of $\mu$ along the surface is responsible for this.


title: A CTMC study of collisions between protons and $H_2^+$ molecular ions

abstract:
  We study numerically collisions between protons and $H_2^+$ molecular ions at
intermediate impact energies by using the Classical Trajectory Monte Carlo
method (CTMC). Total and differential cross sections are computed. The results
are compared with: a) the standard one electron--two nucleon scattering, and b)
the quantum mechanical treatment of the $ H^{+} - H^{+}_{2} $ scattering.


title: On the classical treatment of the Stark effect in hydrogen atoms

abstract:
  A classical model of the hydrogen atom in a static electric field is studied,
basing upon the work [ Hooker A. et al, {\it Phys. Rev. A}, 55 (1997) 4609 ].
In that work the electrons are supposed to move along Kepler orbits around the
nucleus, while interacting with the external field. That classical model
reproduces very well the true energy shift of the linear Stark effect. The
agreement with the second order effect is poor. It is shown here that the
results for the quadratic Stark effect may be considerably improved if the
electrons are still allowed to move along classical trajectories, but whose
initial conditions are statistically sampled from a distribution resembling the
quantum mechanical one.


title: A magnetic guide for cold atoms

abstract:
  We propose a novel method for guiding cold, neutral atoms using static
magnetic fields. A theoretical study of the magnetic field produced by a tube
consisting of two identical, interwound solenoids carrying equal but opposite
currents is presented. This field is almost zero throughout the centre of the
tube, but it increases with exponential rapidity as one approaches the walls
formed by the current carrying wires. Hence, cold atoms passing through the
tube may be reflected by magnetic mirror effects near the walls. Applying this
technique to a free-falling cloud of magneto-optically cooled caesium atoms we
hope to construct atomic guides to facilitate the manipulation of cold atomic
beams.


title:
Equations of Motion from Field Equations and a Gauge-invariant
  Variational Principle for the Motion of Charged Particles

abstract:
  New, gauge-independent, second-order Lagrangian for the motion of classical,
charged test particles is proposed. It differs from the standard,
gauge-dependent, first order Lagrangian by boundary terms only. A new method of
deriving equations of motion from field equations is developed. When applied to
classical electrodynamics, this method enables us to obtain unambigously the
above, second order Lagrangian from the general energy-momentum conservation
principle.


title: Carbon Coated Gas Electron Multipliers

abstract:
  Gas electron multipliers (GEMs) have been overcoated with a high resistivity
10e14 - 10e15 Ohms / square amorphous carbon layer. The coating avoids charging
up of the holes and provides a constant gain immediately after switching on
independent of the rate. The gain uniformity across the GEM is improved.
Coating opens the possibility to produce thick GEMs of very high gain.


title:
Effect of Anion Triiodide on the Main Phase Transition of Fully Hydrated
  Dipalmitoylphosphatidylcholine Bilayers

abstract:
  The paper describes the effect of anion I-3 on thermotropic mesomorphism of
fully hydrated dipalmitoylphosphatidylcholine bilayers. The biphasic behaviour
of melting temperature - I-3 concentration dependence and the increase of DELTA
T values with I-3 concentration (DELTA T = melting temperature - freezing
temperature) suggest the appearance of interdigitated phase of bilayers induced
by I-3 ions.


title:
Multi-Bunch Dynamics in RF Photoinjectors Through an Envelope Equation
  Approach

abstract:
  Free Electron Lasers driven by Super-Conducting Linacs require the
generation, acceleration and transport of trains of bunches with high charge,
high repetition rate and low emittance. A numerical model already developed for
the modeling of beam dynamics in SC Linacs has been now extended to treat RF
guns with proper description of the photocathode bunch generation. The model
algorithm is based on a coupled integration of Newton and Maxwell equations
under a slowly varying envelope approximation for the time evolution of mode
amplitudes in the accelerating structure and an envelope equation description
for a set of bunch slices. In this way beam loading effects and higher order
modes excitation can be studied. The application to the TTF-FEL injector as a
particular design is presented and the optimization according to the invariant
envelope concept is discussed, in the frame of single bunch calculations
compared to the results of other multi-particle codes.


title: Equation of state of fully ionized electron-ion plasmas

abstract:
  Thermodynamic quantities of Coulomb plasmas consisting of point-like ions
immersed in a compressible, polarizable electron background are calculated for
ion charges Z=1 to 26 and for a wide domain of plasma parameters ranging from
the Debye-Hueckel limit to the crystallization point and from the region of
nondegenerate to fully degenerate nonrelativistic or relativistic electrons.
The calculations are based on the linear-response theory for the electron-ion
interaction, including the local-field corrections in the electronic dielectric
function. The thermodynamic quantities are calculated in the framework of the
N-body hypernetted-chain equations and fitted by analytic expressions. We
present also accurate analytic approximations for the free energy of the ideal
electron gas at arbitrary degeneracy and relativity and for the excess free
energy of the one-component plasma of ions (OCP) derived from Monte Carlo
simulations.
  The extension to multi-ionic mixtures is discussed within the framework of
the linear mixing rule. These formulae provide a completely analytic, accurate
description of the thermodynamic quantities of fully ionized electron-ion
Coulomb plasmas, a useful tool for various applications from liquid state
theory to dense stellar matter.


title: Relativistic Effect of Velocity on Electric Charge and Lorentz Force

abstract: This paper has been withdrawn due to crucial errors.


title:
E. Noether's Discovery of the Deep Connection Between Symmetries and
  Conservation Laws

abstract:
  Emmy Noether proved two deep theorems, and their converses, on the connection
between symmetries and conservation laws. Because these theorems are not in the
mainstream of her scholarly work, which was the development of modern abstract
algebra, it is of some historical interest to examine how she came to make
these discoveries. The present paper is an historical account of the
circumstances in which she discovered and proved these theorems which
physicists refer to collectively as Noether's Theorem. The work was done soon
after Hilbert's discovery of the variational principle which gives the field
equations of general relativity. The failure of local energy conservation in
the general theory was a problem that concerned people at that time, among them
David Hilbert, Felix Klein, and Albert Einstein. Noether's theorems solved this
problem. With her characteristically deep insight and thorough analysis, in
solving that problem she discovered very general theorems that have profoundly
influenced modern physics.

categories: physics.hist-ph astro-ph gr-qc hep-th math-ph math.MP


title: Multi-cell RF Injectors Driven by Thermoionic Cathodes

abstract:
  We present the anticipated performances of a multi-cell RF injector operated
either with a thermoionic cathode or with a gated photo-cathode. By means of a
magnetic compression and a Coherent Spontaneous Emission seeded FEL radiating
at 100 to 200 mm, the system produces a beam fully bunched with a 200 A peak
current at 2 mm.mrad rms emittance. The electron bunch is a few FEL buckets
long and phase-locked to the RF so to make this device an ideal injector for
second generation plasma acceleration experiments.


title: When an experiment is crucial?

abstract:
  Although we accept that Physics is, as a last resort, an experimental
science, the relationship between theory and experiment is far away from being
trivial. Any experiment is always explained within a determinate theoretical
context and, at the same time, an experiment can give suggestions for theories
or even can bring new theoretical challenges. Thus, we cannot say without
ambiguity when an experiment is a crucial one.


title: Note on "Electromagnetism and Gravitation"

abstract:
  We obtain Hamilton equations for the gravitational field and demonstrate the
conservation of total energy. We derive the Poisson bracket equation for a
general dynamical variable.


title:
A dynamic programming algorithm for RNA structure prediction including
  pseudoknots

abstract:
  We describe a dynamic programming algorithm for predicting optimal RNA
secondary structure, including pseudoknots. The algorithm has a worst case
complexity of ${\cal O}(N^6)$ in time and ${\cal O}(N^4)$ in storage. The
description of the algorithm is complex, which led us to adopt a useful
graphical representation (Feynman diagrams) borrowed from quantum field theory.
We present an implementation of the algorithm that generates the optimal
minimum energy structure for a single RNA sequence, using standard RNA folding
thermodynamic parameters augmented by a few parameters describing the
thermodynamic stability of pseudoknots. We demonstrate the properties of the
algorithm by using it to predict structures for several small pseudoknotted and
non-pseudoknotted RNAs. Although the time and memory demands of the algorithm
are steep, we believe this is the first algorithm to be able to fold optimal
(minimum energy) pseudoknotted RNAs with the accepted RNA thermodynamic model.


title: Ponderomotive force of quasi-particles in a plasma

abstract:
  We derive the force exerted in the background plasma by an arbitrary
distribution of non interacting quasi-particles, corresponding to either
collective excitations of the plasma (plasmons, phonons) or em dressed
particles (photons, neutrinos). Our approach is based on the effective
Hamiltonian describing the quasi-classical dynamics of the individual particles
in the presence of a background medium. We recover the usual results for the
relativistic ponderomotive force of a photon gas, and we derive the force, due
to weak interactions, exerted by the electron-neutrinos in a background medium
containing electrons, positrons and neutrons with arbitrary distribution
functions. Generalization to other background species and other neutrino
flavors is also discussed.


title: Comment on "Ponderomotive force due to neutrinos"

abstract:
  The derivation of the ponderomotive force due to neutrinos by Hardy and
Melrose, Phys.Rev.D v.54, p.6491 (1996) is based on a flawed analysis of the
ponderomotive force concept. Their conclusions also contain an erroneous
physical assumption related to the neutrino emission in supernovae. A correct
analysis shows the importance of the ponderomotive force due to neutrinos in
type II supernovae explosions.


title: A new method for numerical inversion of the Laplace transform

abstract:
  A formula of Doetsch ({\em Math. Zeitschr.} {\bf 42}, 263 (1937)) is
generalized and used to numerically invert the one-sided Laplace transform
${\hat C}(\beta)$. The necessary input is only the values of ${\hat C}(\beta)$
on the positive real axis. The method is applicable provided that the functions
$\hat{C}(\beta)$ belong to the function space $L^2_\alpha$ defined by the
condition that $ G(x) = e^{x\alpha}\hat{C}(e^x),~ \alpha > 0$ has to be square
integrable. This space includes sums of exponential decays ${\hat
C}(\beta)=\sum_n^{\infty}a_n e^{-\beta E_n}$, e.g. partition functions with
$a_n = 1$. In practice, the inversion algorithm consists of two subsequent fast
Fourier transforms. High accuracy inverted data can be obtained, provided that
the signal is also highly accurate. The method is demonstrated for a harmonic
partition function and resonant transmission through a barrier. We find
accurately inverted functions even in the presence of noise.


title:
Nonadiabatic dynamics in evaporative cooling of trapped atoms by a radio
  frequency field

abstract:
  Magnetically trapped neutral atoms can be cooled with the evaporation
technique. This is typically done by using a radiofrequency (rf) field that
adiabatically couples trapped and untrapped internal atomic states for atoms
with kinetic energies above a value set by the field frequency. The rf-field
can also induce nonadiabatic changes of internal atomic spin states (F,M) that
lead to heating and enhanced loss of atoms. In this paper we use wave packet
simulations to show that the evaporation process can induce these nonadiabatic
transitions which change the internal spin state of doubly spin-polarized (2,2)
trapped atoms. We also verify the validity of a multistate Landau-Zener model
in describing the nonadiabatic dynamics. In addition, we calculate exchange
relaxation rate coefficients for collisions between atoms in the (2,M) states
of 23-Na atoms. Large exchange relaxation coefficients for 23-Na as compared to
87-Rb F=2 suggest that evaporative cooling of (2,2) Na will be more difficult
than for the corresponding state of Rb.


title: Mathematical aspects of numerical solution of hyperbolic systems

abstract:
  A number of physical phenomena are described by nonlinear hyperbolic
equations. Presence of discontinuous solutions motivates the necessity of
development of reliable numerical methods based on the fundamental mathematical
properties of hyperbolic systems. Construction of such methods for systems more
complicated that the Euler gas dynamic systems requires the investigation of
existence and uniqueness of self-similar solution to be used in the development
of discontinuity-capturing high-resolution numerical methods. This frequently
necessitates the study of the behavior of discontinuities under vanishing
viscosity and dispersion. We discuss these problems in the application to the
mahnetohydrodynamic equations, nonlinear waves in elastic media, and
electromagnetic waves in magnetics.
  Paper presented to the 7th International Conference on Hyperbolic Problems.
To be published by Birkhauser.


title:
The Self-Force of a Charged Particle in Classical Electrodynamics with a
  Cut-off

abstract:
  We discuss, in the context of classical electrodynamics with a Lorentz
invariant cut-off at short distances, the self-force acting on a point charged
particle. It follows that the electromagnetic mass of the point charge occurs
in the equation of motion in a form consistent with special relativity. We find
that the exact equation of motion does not exhibit runaway solutions or
non-causal behavior, when the cut-off is larger than half of the classical
radius of the electron.


title:
Generalized Lorentzian Adjustment of Reference Frames and Waves of
  Transformation of Spacetime

abstract:
  It is demonstrated that any two reference frames (RFs), which are uniformly
and rectilinearly moving relative to each other, can be adjusted via (possibly
anisotropic) rescaling and re-synchronization so that the resulting pair of RFs
is Lorentzian; this statement remains true if the word "Lorentzian" is replaced
by "Galilean" or "Riemannian", i.e., if a finite positive value of $c^2$ is
replaced by $\infty$ or by a negative real number. In this particular sense,
the Lorentzian, as well as Galilean or Riemannian, phenomenon turns out to be
merely a matter of an arbitrary choice of appropriate rescaling and
re-synchronization of any given pair of RFs. Generalizations and refinements of
this result are obtained, including universal generalized Lorentzian adjustment
via rescaling and re-synchronization of arbitrarily large families of RFs.
Alternatively, the generalized Lorentzian property of a pair of RFs is shown to
be a consequence of reciprocity and isotropy, with no adjustment needed in this
case. The universality of light and of the corresponding Lorentzian property of
the spacetime is questioned. Waves of transformation of spacetime are
introduced, which have in a certain sense a more universal character than
electromagnetic or gravitational waves.


title: When a mass term does not represent a mass

abstract:
  The definition of mass of a scalar field in a curved space has often been
generalized by grouping coupling terms between the field and the Ricci
curvature with non-curvature-related mass terms. In a broader point of view,
one sees that a common misunderstanding resulting from such an identification
leads one, in the case of the spin 2 field, to regard the cosmological constant
as a non-vanishing mass of cosmological origin for the graviton. Similarly,
there are inconsistencies for the spin 1 field. Instead, the intrinsic mass of
a field should be regarded as being independent of the background curvature.

categories: physics.class-ph astro-ph gr-qc physics.ed-ph


title: Photonic Band Gaps of Three-Dimensional Face-Centered Cubic Lattices

abstract:
  We show that the photonic analogue of the Korringa-Kohn-Rostocker method is a
viable alternative to the plane-wave method to analyze the spectrum of
electromagnetic waves in a three-dimensional periodic dielectric lattice.
Firstly, in the case of an fcc lattice of homogeneous dielectric spheres, we
reproduce the main features of the spectrum obtained by the plane wave method,
namely that for a sufficiently high dielectric contrast a full gap opens in the
spectrum between the eights and ninth bands if the dielectric constant
$\epsilon_s$ of spheres is lower than the dielectric constant $\epsilon_b$ of
the background medium. If $\epsilon_s> \epsilon_b$, no gap is found in the
spectrum. The maximal value of the relative band-gap width approaches 14% in
the close-packed case and decreases monotonically as the filling fraction
decreases. The lowest dielectric contrast $\epsilon_b/\epsilon_s$ for which a
full gap opens in the spectrum is determined to be 8.13. Eventually, in the
case of an fcc lattice of coated spheres, we demonstrate that a suitable
coating can enhance gap widths by as much as 50%.

categories: physics.class-ph cond-mat math-ph math.MP physics.optics


title: "Water Buckyballs" Chemical, Catalytic, and Cosmic Implications

abstract:
  Possible chemical, catalytic, and cosmic roles of charged pentagonal
dodecahedral water clusters having "buckyball-like" symmetry are discussed on
the basis of electronic and vibronic theory and experiment. The electronic
structure in conjunction with the dynamic Jahn-Teller effect is argued to make
water buckyballs catalysts and oxygenates for fuel combustion and active agents
in biological systems. The broad electronic and unique low-frequency vibronic
spectra of water buckyballs may explain certain diffuse interstellar bands,
far-infrared, ultraviolet, and x-ray cosmic background radiation, and some
"missing cosmic baryonic matter". The relevance of water buckyballs to the
properties of liquid and supercritical water concludes the paper.


title:
Oligopeptides' frequencies in the classification of proteins' primary
  structures

abstract:
  This paper reports about an approach to the classification of proteins'
primary structures taking advantage of the Self Organizing Maps algorithm and
of a numerical coding of the aminoacids based upon their physico-chemical
properties. Hydrophobicity, volume, surface area, hydrophilicity, bulkiness,
refractivity and polarity were subjected to a Principal Component Analysis and
the first two principal components, explaining 84.8 % of the total observed
variability, were used to cluster the aminoacids into 4 or 5 classes through a
k-means algorithm. This leads to an economical representation of the primary
structures which, in the construction of the input vectors for the Self
Organizing Maps algorithm, allows the consideration of up to tri- and
tetrapeptides' frequency matrices with minimal computational overload. In
comparison with previously explored conditions, namely symbolic coding of
aminoacids and dipeptides frequencies, no significant improvement was observed
in the classification of 69 cytochromes of the c type, characterized by a high
degree of structural and functional similarity, while a substantial improvement
occurred in the case of a data set including quite heterogeneous primary
structures.


title: Lengths on rotating platforms

abstract:
  The paper treats the issue of the length of a rotating circumference as seen
from on board the moving disk and from an inertial reference frame. It is shown
that, properly defining a measuring process, the result is in both cases 2piR
thus dissolving the Ehrenfest paradox. The same holds good when considering
that, for the rotating observer, the perceived radius coincides with the
curvature radius of a space-time helix and a complete round trip corresponds to
an angle which differs from the one seen by the inertial observer. The apparent
contradiction with the Lorentz contraction is discussed.


title: Does light exert Abraham's force in a transparent medium?

abstract:
  Abraham's force seems to have been observed in very low frequency
experiments, but the existence of an Abraham's force exerted by light is still
to be proved. Twenty years ago Brevik proposed an experiment for checking what
forces light exert in the interior of a transparent medium. It is argued that
his proposal is feasible today with a detection method now at hand, thanks to
the great improvements achieved in manufacturing optical fibres with the
required physical properties.


title:
Concentrator of laser energy for thin vapour cloud production near a
  surface

abstract:
  A novel scheme is presented for production of a thin ($<1$ mm) uniform vapor
layer over a large surface area ($>100$ cm$^2$) by pulsed laser ablation of a
solid surface. Instead of dispersing the laser energy uniformly over the
surface, a modified Fabry-Perot interferometer is employed to concentrate the
laser energy in very narrow closely-spaced concentric rings. This approach may
be optimized to minimum total laser energy for the desired vapor density.
Furthermore, since the vapor is produced from a small fraction of the total
surface area, the local ablation depth is large, which minimized the fraction
of surface contamination in the vapor.
  Key words: laser evaporation, thin gas layer formation.


title:
Joint Bayesian Treatment of Poisson and Gaussian Experiments in a
  Chi-squared Statistic

abstract:
  Bayesian Poisson probability distributions for the average n can be
analytically converted into equivalent chi-squared distributions. These can
then be combined with other Gaussian or Bayesian Poisson distributions to make
a total chi-squared distribution. This allows the usual treatment of
chi-squared contours but now with both Poisson and Gaussian statistics
experiments. This is illustrated with the case of neutrino oscillations.


title: Continuous Probability Distributions from Finite Data

abstract:
  Recent approaches to the problem of inferring a continuous probability
distribution from a finite set of data have used a scalar field theory for the
form of the prior probability distribution. This letter presents a more general
form for the prior distribution that has a geometrical interpretation which is
useful for tailoring prior distributions to the needs of each application.
Examples are presented that demonstrate some of the capabilities of this
approach, including the applicability of this approach to problems of more than
one dimension.


title:
Comment on "Accurate relativistic effective potentials for the sixth-row
  main group elements" [J.Chem.Phys. 107, 9975 (1997)]

abstract:
  Critical remarks in respect to the Generalized Relativistic Effective Core
Potential in the recent article of S.A.Wildman at al. are discussed and shown
to be incorrect.


title: 1D Toy Model For Trapping Neutral Particles

abstract:
  We study, both classically and quantum-mechanically, the problem of a neutral
particle with spin, moving in one-dimension in an inhomogeneous magnetic field.
This problem serves for us as a toy model to study the trapping of neutral
particles. We identify K, the ratio between the precessional frequency of the
particle and its vibration frequency, as the relevant parameter of the problem.
Classicaly, we find that when the magnetic moment is antiparallel to the
direction of the magnetic field, the particle is trapped provided that K<0.5.
We also find that viscous friction, be it translational or precessional,
destabilizes the system. Quantum-mechanically, we study the problem of spin
half particle in the same field. Treating K as a small parameter for the
perturbation from the adiabatic Hamiltonian, we find the lifetime of the
particle in its trapped ground-state.


title:
Quantitative analysis by renormalized entropy of invasive
  electroencephalograph recordings in focal epilepsy

abstract:
  Invasive electroencephalograph (EEG) recordings of ten patients suffering
from focal epilepsy were analyzed using the method of renormalized entropy.
Introduced as a complexity measure for the different regimes of a dynamical
system, the feature was tested here for its spatio-temporal behavior in
epileptic seizures. In all patients a decrease of renormalized entropy within
the ictal phase of seizure was found. Furthermore, the strength of this
decrease is monotonically related to the distance of the recording location to
the focus. The results suggest that the method of renormalized entropy is a
useful procedure for clinical applications like seizure detection and
localization of epileptic foci.


title: Are We Cruising a Hypothesis Space?

abstract:
  This paper is about Information Geometry, a relatively new subject within
mathematical statistics that attempts to study the problem of inference by
using tools from modern differential geometry. This paper provides an overview
of some of the achievements and possible future applications of this subject to
physics.


title: Unreal Probabilities: Partial Truth with Clifford Numbers

abstract:
  This paper introduces and studies the basic properties of Clifford algebra
valued conditional measures.


title: A Rational Approach to Ring Flexibility in Internal Coordinate Dynamics

abstract:
  Internal coordinate molecular dynamics (ICMD) is an efficient method for
studying biopolymers, but it is readily applicable only to molecules with tree
topologies, that is with no internal flexible rings. Common examples violating
this condition are prolines and loops closed by S-S bridges in proteins. The
most important such case, however, is nucleic acids because the flexibility of
the furanose rings always plays an essential role in conformational transitions
both in DNA and RNA. There are a few long-known theoretical approaches to this
problem, but, in practice, rings with fixed bond lengths are closed by adding
appropriate harmonic distance restraints, which is not always acceptable
especially in dynamics. This paper tries to overcome this handicap of ICMD and
proposes a rational strategy which results in practical numerical algorithms.
It gives a unified analytical treatment which shows that this problem is very
close to the difficulties encountered by the method of constraints in Cartesian
coordinate dynamics, and certain ideas of the latter appear helpful in the
context of ICMD. The method is affordable for large molecules and generally
applicable to all kinds of rings. A specific implementation for five-membered
rings is described and tested for a proline-rich polypeptide and a decamer DNA
duplex. In both cases conditions are found which make possible time steps
around 10 fsec in ICMD calculations.

categories: physics.comp-ph physics.bio-ph physics.chem-ph q-bio.BM


title: A fully ab initio quartic force field of spectroscopic quality for SO_3

abstract:
  The quartic force field of SO$_3$ was computed fully ab initio using coupled
cluster (CCSD(T)) methods and basis sets of up to $spdfgh$ quality. The effect
of inner-shell correlation was taken into account. The addition of tight $d$
functions is found to be essential for accurate geometries and harmonic
frequencies. The equilibrium geometry and vibrational fundamentals are
reproduced to within 0.0003 \AA and (on average) 1.15 cm^{-1}, respectively. We
recommend the following revised values for the harmonic frequencies: $\omega_1
= 1082.7, \omega_2 = 502.6, \omega_3 = 1415.4, \omega_4 = 534.0 cm^{-1}$. In
addition, we have shown that the addition of inner polarization functions to
second-row elements is highly desirable even with more approximate methods like
B3LYP, and greatly improves the quality of computed geometries and harmonic
frequencies of second-row compounds at negligible extra computational cost. For
larger such molecules, the B3LYP/VTZ+1 level of theory should be a very good
compromise between accuracy and computational cost.


title:
Ab initio thermochemistry beyond chemical accuracy for first-and
  second-row compounds

abstract:
  By judicious use of extrapolations to the 1-particle basis set limit and
$n$-particle calibration techniques, total atomization energies of molecules
with up to four heavy atoms can be obtained with calibration accuracy (1 kJ/mol
or better, on average) without any empirical correction. For the SCF energy a
3-point geometric extrapolation is the method of choice. For the MP2
correlation energy, a 2-point $A+B/(l+1/2)^3$ extrapolation is recommended,
while for CCSD and CCSD(T) correlation energies we prefer the 3-point
$A+B/(l+1/2)^C$ formula. Addition of high-exponent `inner polarization
functions' to second-row atoms is essential for reliable results. For the
highest accuracy, accounts are required of inner-shell correlation, atomic
spin-orbit splitting, anharmonicity in the zero-point energy, and scalar
relativistic effects.