title:
Technique for measuring the parameters of polarization of an ultrasonic
  wave

abstract:
  Method for precise measurements of the ellipticity and rotation of the
polarization of a transverse ultrasonic wave is presented. It is applicable for
investigating the acoustic analogs of the Faraday, Cotton-Mouton, and Kerr
effects. The technique consists of measuring amplitude of the voltage on the
receiving piezoelectric transducer at a certain magnetic induction B, relative
to an initial one using three different positions of the transducer with futher
processing the data with the formulars given in the paper.


title:
Inquiries into the Nature of Free Energy and Entropy in Respect to
  Biochemical Thermodynamics

abstract:
  Free energy and entropy are examined in detail from the standpoint of
classical thermodynamics. The approach is logically based on the fact that
thermodynamic work is mediated by thermal energy through the tendency for
nonthermal energy to convert spontaneously into thermal energy and for thermal
energy to distribute spontaneously and uniformly within the accessible space.
The fact that free energy is a Second-Law, expendable energy that makes it
possible for thermodynamic work to be done at finite rates is emphasized.
Entropy, as originally defined, is pointed out to be the capacity factor for
thermal energy that is hidden with respect to temperature; it serves to
evaluate the practical quality of thermal energy and to account for changes in
the amounts of latent thermal energies in systems maintained at constant
temperature. A major objective was to clarify the means by which free energy is
transferred and conserved in sequences of biological reactions coupled by
freely diffusible intermediates. In achieving this objective it was found
necessary to distinguish between a 'characteristic free energy' possessed by
all First-Law energies in amounts equivalent to the amounts of the energies
themselves and a 'free energy of concentration' that is intrinsically
mechanical and relatively elusive in that it can appear to be free of First-Law
energy. The findings in this regard serve to clarify the fact that the transfer
of chemical potential energy from one repository to another along sequences of
biological reactions of the above sort occurs through transfer of the First-Law
energy as thermal energy and transfer of the Second-Law energy as free energy
of concentration.

categories: physics.ed-ph cond-mat.mtrl-sci physics.bio-ph physics.chem-ph quant-ph


title: Statistical mechanics of the shallow water system

abstract:
  We extend the formalism of the statistical theory developed for the 2D Euler
equation to the case of shallow water system. Relaxation equations towards the
maximum entropy state are proposed, which provide a parametrization of sub-grid
scale eddies in 2D compressible turbulence.


title: The information bottleneck method

abstract:
  We define the relevant information in a signal $x\in X$ as being the
information that this signal provides about another signal $y\in \Y$. Examples
include the information that face images provide about the names of the people
portrayed, or the information that speech sounds provide about the words
spoken. Understanding the signal $x$ requires more than just predicting $y$, it
also requires specifying which features of $\X$ play a role in the prediction.
We formalize this problem as that of finding a short code for $\X$ that
preserves the maximum information about $\Y$. That is, we squeeze the
information that $\X$ provides about $\Y$ through a `bottleneck' formed by a
limited set of codewords $\tX$. This constrained optimization problem can be
seen as a generalization of rate distortion theory in which the distortion
measure $d(x,\x)$ emerges from the joint statistics of $\X$ and $\Y$. This
approach yields an exact set of self consistent equations for the coding rules
$X \to \tX$ and $\tX \to \Y$. Solutions to these equations can be found by a
convergent re-estimation method that generalizes the Blahut-Arimoto algorithm.
Our variational principle provides a surprisingly rich framework for discussing
a variety of problems in signal processing and learning, as will be described
in detail elsewhere.

categories: physics.data-an cond-mat.dis-nn cs.LG nlin.AO


title:
Precision measurements of sodium-sodium and sodium-noble gas molecular
  absorption

abstract:
  Experimental apparatus and measurement technique are described for precision
absorption measurements in sodium - noble gas mixtures. The absolute absorption
coefficient is measured in the wavelength range from 425 nm to 760 nm with 2%
uncertainty and spectral resolution of 0.02 nm. The precision is achieved by
using a specially designed absorption cell with an accurately defined
absorption path length, low noise CCD detector and double-beam absorption
measurement scheme. The experimental set-up and the cell design details are
given. Measurements of sodium atomic number density with 5% uncertainty
complement absorption coefficient measurements and allow derivation of the
reduced absorption coefficients for certain spectral features. The sodium
atomic number density is measured using the anomalous dispersion method. The
accuracy of this method is improved by employing a least-squares fit to the
interference image recorded with CCD detector and the details of this technique
are given. The measurements are aimed at stringent testing of theoretical
calculations and improving the values of molecular parameters used in
calculations.


title: Spatial Gravity

abstract:
  Hubble's correlation of red-shift with distance reveals that the universe is
expanding, and that spacetime curvature has increased over time. And since time
and space have equal status as dimensions, an object moving through time
experiences increasing spatial curvature due to expansion, just as it does when
moving through space towards a massive body. So expansion must increase
gravity, and this increase would be proportional to the amount of red-shift.
The kinetic energy of expansion is thus exchanged for curvature of spacetime,
and this results in spatial gravity. Momentum therefore fuels both spatial and
massive gravity. And spatial gravity, which must therefore be proportional to
the size of the universe, combines with massive gravity to produce overall
gravity. A cosmological factor proportional to the size of the universe is
therefore appropriate. And the very expansion which causes increasing spatial
gravity, should cause expansion to be self-limiting.


title:
Real time encoding of motion: Answerable questions and questionable
  answers from the fly's visual system

abstract:
  In the past decade, a small corner of the fly's visual system has become an
important testing ground for ideas about coding and computation in the nervous
system. A number of results demonstrate that this system operates with a
precision and efficiency near the limits imposed by physics, and more generally
these results point to the reliability and efficiency of the strategies that
nature has selected for representing and processing visual signals. A recent
series of papers by Egelhaaf and coworkers, however, suggests that almost all
these conclusions are incorrect. In this contribution we place these
controversies in a larger context, emphasizing that the arguments are not just
about flies, but rather about how we should quantify the neural response to
complex, naturalistic inputs. As an example, Egelhaaf et al. (and many others)
compute certain correlation functions and use the apparent correlation times as
a measure of temporal precision in the neural response. This analysis neglects
the structure of the correlation function at short times, and we show how to
analyze this structure to reveal a temporal precision 30 times better than
suggested by the correlation time; this precision is confirmed by a much more
detailed information theoretic analysis. In reviewing other aspects of the
controversy, we find that the analysis methods used by Egelhaaf et al. suffer
from some mathematical inconsistencies, and that in some cases we are unable to
reproduce their experimental results. Finally, we present results from new
experiments that probe the neural response to inputs that approach more closely
the natural context for freely flying flies. These new experiments demonstrate
that the fly's visual system is even more precise and efficient under natural
conditions than had been inferred from our earlier work.


title: Study of nucleating efficiency of superheated droplets by neutrons

abstract:
  Superheated droplets are proven to be excelent detectors for neutrons and
could be used as a neutron dosimeter. To detect accurately the volume of the
vapour formed upon nucleation and hence to observe the nucleation
quantitatively an air displacement system has been developed.


title: Testing cosmological variability of fundamental constants

abstract:
  One of the topical problems of contemporary physics is a possible variability
of the fundamental constants. Here we consider possible variability of two
dimensionless constants which are most important for calculation of atomic and
molecular spectra (in particular, the X-ray ones): the fine-structure constant
\alpha=e^2/\hbar c and the proton-to-electron mass ratio \mu=m_p/m_e. Values of
the physical constants in the early epochs are estimated directly from
observations of quasars - the most powerful sources of radiation, whose spectra
were formed when the Universe was several times younger than now. A critical
analysis of the available results leads to the conclusion that present-day data
do not reveal any statistically significant evidence for variations of the
fundamental constants under study. The most reliable upper limits to possible
variation rates at the 95% confidence level, obtained in our work, read:
  |\dot\alpha/\alpha| < (1.4e-14)/yr,
  |\dot\mu/\mu| < (1.5e-14)/yr
  on the average over the last ten billion years.


title:
Test Results on the Silicon Pixel Detector for the TTF-FEL Beam
  Trajectory Monitor

abstract:
  Test measurements on the silicon pixel detector for the beam trajectory
monitor at the free electron laser of the TESLA test facility are presented. To
determine the electronic noise of detector and read-out and to calibrate the
signal amplitude of different pixels the 6 keV photons of the manganese K line
are used. Two different methods determine the spatial accuracy of the detector:
In one setup a laser beam is focused to a straight line and moved across the
pixel structure. In the other the detector is scanned using a low-intensity
electron beam of an electron microscope. Both methods show that the symmetry
axis of the detector defines a straight line within 0.4 microns. The
sensitivity of the detector to low energy X-rays is measured using a vacuum
ultraviolet beam at the synchrotron light source HASYLAB. Additionally, the
electron microscope is used to study the radiation hardness of the detector.


title: Matching Conditions on Capillary Ripples: Polarization

abstract:
  The matching conditions at the interface between two non-mixed fluids at rest
are obtained directly using the equation of movement of the whole media. This
is a non-usual point of view in hydrodynamics courses and our aim is to fix
ideas about the intrinsic information contained in the matching conditions, on
fluids in this case. Afterward, it is analyzed the polarization of the normal
modes at the interface and it is shown that this information can be achieved
through a physical analysis and reinforced later by the matching conditions. A
detailed analysis of the matching conditions is given to understand the role
that plays the continuity of the stress tensor through the interface on the
physics of the surface particle movement. The main importance of the viscosity
of each medium is deduced.


title: Surface waves at the interface between two viscous fluids

abstract:
  The Surface Green Function Matching analysis (SGFM) is used to study the
normal modes of the interface oscillations between two non-mixed fluids by
considering the difference in their densities and viscosities. The limiting
case of viscous-inviscid system is used for comparison. The role of the
viscosity and the density ratios on the momentum exchange and on the
polarization of the surface modes is analyzed.


title:
A transferable nonorthogonal tight-binding model of germanium:
  application to small clusters

abstract:
  We have developed a transferable nonorthogonal tight-binding total energy
model for germanium and use it to study small clusters. The cohesive energy,
bulk modulus, elastic constants of bulk germanium can be described by this
model to considerably good extent. The calculated bulk phase diagram for
germanium agrees well with LDA results. The geometries and binding energies
found for small Ge$_n$ clusters with $n=3-10$ are very close to previous {\em
ab initio} calculations and experiments. All these results suggest that this
model can be further applied to the simulation of germanium cluster of larger
size or with longer time scale, for which {\em ab initio} methods is much more
computational expensive.


title: Imprints of Discrete Space Time - A Brief Note

abstract:
  We point out that the observed decay mode of the pion and the Kaon decay
puzzle are really imprints of discrete micro space-time.


title: Puzzle of the constancy of fundamental constants

abstract:
  We discuss experiments and observations aimed at testing the possible
space-time variability of fundamental physical constants, predicted by the
modern theory. Specifically, we consider two of the dimensionless physical
parameters which are important for atomic and molecular physics: the
fine-structure constant and the electron-to-proton mass ratio. We review the
current status of such experiments and critically analyze recent claims of a
detection of the variability of the fine-structure constant on the cosmological
time scale. We stress that such a detection remains to be checked by future
experiments and observations. The tightest of the firmly established upper
limits read that the considered constants could not vary by more than 0.015% on
the scale of 10 Gigayears.


title: The propensity of molecules to spatially align in intense light fields

abstract:
  The propensity of molecules to spatially align along the polarization vector
of intense, pulsed light fields is related to readily-accessible parameters
(molecular polarizabilities, moment of inertia, peak intensity of the light and
its pulse duration). Predictions can now be made of which molecules can be
spatially aligned, and under what circumstances, upon irradiation by intense
light. Accounting for both enhanced ionization and hyperpolarizability, it is
shown that {\it all} molecules can be aligned, even those with the smallest
static polarizability, when subjected to the shortest available laser pulses
(of sufficient intensity).


title: A Brief Note on Discrete Space Effects

abstract:
  We discuss briefly discrete space effects and show that this leads to space
reflection asymmetry and also a minor modification of Einstein's energy-mass
formula.


title:
Harmonically dancing space-time nodes: quantitatively deriving
  relativity, mass, and gravitation

abstract:
  The microscopic structure of space and time is investigated. It is proposed
that space and time of an inertial observer $\Sigma$ are most conveniently
described as a crystal array $\Lambda$, with nodes representing measurement
`tickmarks' and connected by independent quantized harmonic oscillators which
vibrate more severely the faster $\Sigma$ moves with respect to the object
being measured (due to the Uncertainty Principle). The Lorentz transformation
of Special Relativity is derived. Further, mass is understood as a localized
region $\Delta \Lambda$ having higher vibration temperature than that of the
ambient lattice. The effect of relativistic mass increase may then be
calculated without appealing to energy-momentum conservation. The origin of
gravitation is shown to be simply a transport of energy from the boundary of
$\Delta \Lambda$ outwards by lattice phonon conduction, as the system tends
towards equilibrium. Application to a single point mass leads readily to the
Schwarzschild metric, while a new solution is available for two point masses -
a situation where General Relativity is too complicated to work with. The
important consequence is that inertial observers who move at relative speeds
too close to $c$ are no longer linked by the Lorentz transformation, because
the lattice of the `moving' observer has already disintegrated into a liquid
state.


title: Elementary Nonrelativistic Quantum Mechanics

abstract:
  This is a graduate course on elementary quantum mechanics written for the
benefit of undergraduate and graduate students. It is the English version of
physics/0003106, which I did at the suggestion of several students from
different countries. The topics included refer to the postulates of quantum
mechanics, one-dimensional barriers and wells, angular momentum and spin, WKB
method, harmonic oscillator, hydrogen atom, quantum scattering, and partial
waves


title:
The Exchange-correlation Hole of the Si Atom, A Quantum Monte Carlo
  Study

abstract:
  We have studied the exchange-correlation hole and pair correlation function
in the valence shell of the ground-state of the Si atom, using accurate
Slater-Jastrow wavefunctions and the Variational Monte Carlo method. The
exchange-correlation hole shows a number of interesting features caused by the
open shell structure of Si, including a marked transition from efficient to
poor screening behavior as a test majority-spin electron is moved from the
center of a valence 3p orbital onto the axis perpendicular to the occupied 3p
orbitals. This behavior results from the dramatic difference in the exchange
hole in the two cases, which is partially compensated by a corresponding
anisotropy in the correlation hole. In addition we observe an anisotropic
change in the spin density induced by Coulomb correlation, reducing the spatial
overlap between the different spin-components of the density and contributing
to the anisotropy of the correlation hole. In contrast to the longer range
features, we find that the "on-top" correlation hole is well described by
linear density functional theory, for a large range of local density and
magnetization.


title: A unified approach for the solution of the Fokker-Planck equation

abstract:
  This paper explores the use of a discrete singular convolution algorithm as a
unified approach for numerical integration of the Fokker-Planck equation. The
unified features of the discrete singular convolution algorithm are discussed.
It is demonstrated that different implementations of the present algorithm,
such as global, local, Galerkin, collocation, and finite difference, can be
deduced from a single starting point. Three benchmark stochastic systems, the
repulsive Wong process, the Black-Scholes equation and a genuine nonlinear
model, are employed to illustrate the robustness and to test accuracy of the
present approach for the solution of the Fokker-Planck equation via a
time-dependent method. An additional example, the incompressible Euler
equation, is used to further validate the present approach for more difficult
problems. Numerical results indicate that the present unified approach is
robust and accurate for solving the Fokker-Planck equation.


title: Stochastic Resonance in Neuron Models: Endogenous Stimulation Revisited

abstract:
  The paradigm of stochastic resonance (SR)---the idea that signal detection
and transmission may benefit from noise---has met with great interest in both
physics and the neurosciences. We investigate here the consequences of reducing
the dynamics of a periodically driven neuron to a renewal process (stimulation
with reset or endogenous stimulation). This greatly simplifies the mathematical
analysis, but we show that stochastic resonance as reported earlier occurs in
this model only as a consequence of the reduced dynamics.


title: Breit interaction in heavy atoms

abstract:
  In this letter we discuss how to include Breit interaction in calculations of
low-energy properties of heavy atoms in accurate and effective way. In order to
illustrate our approach we give some results for Cs and Tl.


title:
Design and Simulation of a High Frequency High Power Rf Extraction
  Device Using a Dielectric-Loaded Waveguide

abstract:
  We consider the use of a dielectric-loaded structure to extract rf energy
from a high current electron drive beam as a power source for a high energy
two-beam accelerator. This represents an alternative technique which we show to
have some significant advantages over the use of the currently proposed
corrugated metal structures as power extraction devices. We discuss a
particular design that will extract high power rf (0.1 -- 1 GW) from a high
current drive beam. Rf generation and transport in this class of devices have
already been demonstrated at lower frequencies. We discuss the design
parameters for 15 and 30 GHz dielectric transfer structures and some possible
experiments.


title: Quantum Gravity

abstract:
  Gravitons should have momentum just as photons do; and since graviton
momentum would cause compression rather than elongation of spacetime outside of
matter; it does not appear that gravitons are compatible with Swartzchild's
spacetime curvature. Also, since energy is proportional to mass, and mass is
proportional to gravity; the energy of matter is proportional to gravity. The
energy of matter could thus contract space within matter; and because of the
inter-connectedness of space, cause the elongation of space outside of matter.
And this would be compatible with Swartzchild spacetime curvature. Since
gravity could be initiated within matter by the energy of mass, transmitted to
space outside of matter by the inter-connectedness of space; and also
transmitted through space by the same inter-connectedness of space; and since
spatial and relativistic gravities can apparently be produced without the aid
of gravitons; massive gravity could also be produced without gravitons as well.
  Gravity divided by an infinite number of segments would result in zero
expression of gravity, because it could not curve spacetime. So spatial
segments must have a minimum size, which is the Planck length; thus resulting
in quantized space. And since gravity is always expressed over some distance in
space, quantum space would therefore always quantize gravity. So the
non-mediation of gravity by gravitons does not result in unquantized gravity,
because quantum space can quantize gravity; thus making gravitons unproven and
unnecessary, and explaining why gravitons have never been found.


title:
Magnetic Fractal Dimensionality of the Dielectric Breakdown Under Strong
  Magnetic Fields

abstract:
  The formation of breakdown pattern on an insulating surface under the
influence of a transverse magnetic field is theoretically investigated. We have
generalized the Dielectric Breakdown Model (DBM) for the case of external
magnetic field. Concept of the Magnetic Fractal Dimensionality (MFD) is
introduced and its universality is demonstrated. It is shown that MFD saturates
with magnetic fields. The magnetic field dependence of the streamer curvature
is obtained. It is conjectured that nonlinear current interaction is
responsible for the experimentally observed 'spider-legs' like streamer
patterns.


title: M\'etodos Estoc\'asticos em Turbul\^encia Desenvolvida

abstract:
  In this thesis, we use some methods of theory of stochastic process to
approach turbulence in fluid dynamics. We discuss the Kolmogorov model for
fully developed homogeneous turbulence, some recent analytical results to the
1-D Burgers' equation approach turbulence. Nesta disserta\c c\~ao, utilizamos
m\'etodos da teoria de processos estoc\'asticos para a compreens\~ao da
turbul\^encia em fluidos. Discutimos o modelo de Kolmogorov para turbul\^encia
homog\^enea desenvolvida, resultados anal\'\i ticos recentes para a equa\c
c\~ao de Burgers.


title: An inertial range length scale in structure functions

abstract:
  It is shown using experimental and numerical data that within the traditional
inertial subrange defined by where the third order structure function is linear
that the higher order structure function scaling exponents for longitudinal and
transverse structure functions converge only over larger scales, $r>r_S$, where
$r_S$ has scaling intermediate between $\eta$ and $\lambda$ as a function of
$R_\lambda$. Below these scales, scaling exponents cannot be determined for any
of the structure functions without resorting to procedures such as extended
self-similarity (ESS). With ESS, different longitudinal and transverse higher
order exponents are obtained that are consistent with earlier results. The
relationship of these statistics to derivative and pressure statistics, to
turbulent structures and to length scales is discussed.


title: A Cupronickel Rotating Band Pion Production Target for Muon Colliders

abstract:
  A conceptual design is presented for a high power cupronickel pion production
target. It forms a circular band in a horizontal plane with approximate
dimensions of: 2.5 meters radius, 6 cm high and 0.6 cm thick. The target is
continuously rotated at 3 m/s to carry heat away from the production region to
a water cooling channel. Bunches of 16 GeV protons with total energies of 270
kJ and repetition rates of 15 Hz are incident tangentially to arc of the target
along the symmetry axis of a 20 Tesla solenoidal magnetic capture channel. The
mechanical layout and cooling setup are described. Results are presented from
realistic MARS Monte Carlo computer simulations of the pion yield and energy
deposition in the target. ANSYS finite element calculations are beginning to
give predictions for the resultant shock heating stresses.


title: Metrology and Time

abstract:
  The algorithm Pi/sinx reveals an elliptic excess which acts as the real
component (Space) inducing the imaginary component (Time). Key words :
metrology, chronogenesis, tropic year, anomalistic year.
  -----
  L 'algorithme Pi/sinx revele un excedent elliptique constituant la composante
active d ' espace dont la composante reactive exprime la chronogenese tropique
aussi bien qu ' anomalistique.. Mots-cles : metrologie, chronogenese, annee
tropique, annee anomalistique


title:
Rotating Band Pion Production Targets for Muon Colliders and Neutrino
  Factories

abstract:
  An update is presented on a conceptual design for a pion production target
station using a rotating cupronickel band and that was originally proposed for
use at a muon collider facility with a 4 MW pulsed proton beam. After reviewing
the salient design features and motivations for this target, ongoing studies
are described that are attempting to benchmark the thermal stresses and
radiation damage on the target band using data from the Fermilab antiproton
source and other operating targets. Possible parameter optimizations and
alternative technologies for the rotating band are surveyed, including
discussion on the the various proton beam parameters that might be encountered
for rotating band targets at either muon colliders or neutrino factories.
Finally, an outline is proposed for a possible R&D path towards capability for
the actual construction of rotating band pion production targets.


title:
Parameter Sets for 10 TeV and 100 TeV Muon Colliders, and their Study at
  the HEMC'99 Workshop

abstract:
  A focal point for the HEMC'99 workshop was the evaluation of straw-man
parameter sets for the acceleration and collider rings of muon colliders at
center of mass energies of 10 TeV and 100 TeV. These self-consistent parameter
sets are presented and discussed. The methods and assumptions used in their
generation are described and motivations are given for the specific choices of
parameter values. The assessment of the parameter sets during the workshop is
then reviewed and the implications for the feasibility of many-TeV muon
colliders are evaluated. Finally, a preview is given of plans for iterating on
the parameter sets and, more generally, for future feasibility studies on
many-TeV muon colliders.


title:
One a topological secret of gravity and its surprises for astrophysics,
  cosmology and particle physics

abstract:
  It is argued that the surface radius of a compact source can not be less than
its gravitational radius due to the strong gravitational time dilation effects.
The such "topological" difference between the Newtonian and relativistic
gravity leads to the known observable effects. The hierarchy of supercompact
stars, more massive than neutron stars, such as heavy baryon, quark (subquark?)
and other heavy particle stars is predicted instead of the black holes. The
lack of the cosmological singularity and a gravitational nature of the
regularizations of loop divergencies in quantum field theory are also
discussed.


title:
Is it Possible to Describe Economical Phenomena by Methods of
  Statistical Physics of Open Systems?

abstract:
  The methods of statistical physics of open systems are used for describing
the time dependence of economic characteristics (income, profit, cost, supply,
currency etc.) and their correlations with each other. Nonlinear equations
(analogies of known reaction-diffusion, kinetic, Langevin equation) describing
appearance of bifurcations, self-sustained oscillational processes,
self-organizations in economic phenomena are offered.


title:
About the Dependence of the Currency Exchange Rate at Time and National
  Dividend, Investments Size, Difference Between Total Demand and Supply

abstract:
  The time dependence of the currency exchange rate K treated as a function of
national dividend, investments and difference between total demand for a goods
and supply is considered. To do this a proposed earlier general algorithm of
economic processes describing on the basis of the equations for K like the
equations of statistical physics of open systems is used. A number of
differential equations (including nonlinear ones too) determining the time
dependence of the exchange rate (including oscillations) is obtained.


title:
Time symmetric action-at-a-distance electrodynamics and the structure of
  SpaceTime

abstract:
  This paper begins with a critical analysis of the concept of 'material point
particle'. We argue that this concept is incompatible with the force laws of
action-at-a-distance electrodynamics, and we suggest that the trajectory of a
particle (the world-line) should be looked upon as a string in static
equilibrium. By complementing our model with a time symmetric interaction law,
we are led to a straightforward derivation of the principles underlying the
electromagnetic interaction between two uniformly moving charged particles. An
extension of our theory to the case of particles in arbitrary motion shows that
we have to modify Maxwell's equations of the microscopic electromagnetic field,
in order to accommodate a field-strength tensor which is no longer
antisymmetric. It is further argued that the radiation reaction force gives
another example of a 4-force which is not orthogonal to the 4-velocity, thus
leading to a variable rest mass. The variation of the rest mass is then
discussed from the point of view of the equivalence principle of general
relativity, and we end up with a theoretical derivation of the homogenous
Maxwell's equations.


title: Do The Particles With Nonzero Mass Need Duality ?

abstract:
  Unsufficiency of conditions for the formation of interference in monoparticle
"which path" experiments is proven. The version of corpuscular interpretation
of diffraction pattern based on the action discreteness is presented, which
makes unnecessary to accredit duality to the particles with nonzero mass. The
experiment to check the above mentioned concepts are proposed.


title: Multi frequency evaporative cooling to BEC in a high magnetic field

abstract:
  We demonstrate a way to circumvent the interruption of evaporative cooling
observed at high bias field for $^{87}$Rb atoms trapped in the (F=2, m=+2)
ground state. Our scheme uses a 3-frequencies-RF-knife achieved by mixing two
RF frequencies. This compensates part of the non linearity of the Zeeman
effect, allowing us to achieve BEC where standard 1-frequency-RF-knife
evaporation method did not work. We are able to get efficient evaporative
cooling, provided that the residual detuning between the transition and the RF
frequencies in our scheme is smaller than the power broadening of the RF
transitions at the end of the evaporation ramp.


title:
Frequency stabilization of a monolithic Nd:YAG ring laser by controlling
  the power of the laser-diode pump source

abstract:
  The frequency of a 700mW monolithic non-planar Nd:YAG ring laser (NPRO)
depends with a large coupling coefficient (some MHz/mW) on the power of its
laser-diode pump source. Using this effect we demonstrate the frequency
stabilization of an NPRO to a frequency reference by feeding back to the
current of its pump diodes. We achieved an error point frequency noise smaller
than 1mHz/sqrt(Hz), and simultaneously a reduction of the power noise of the
NPRO by 10dB without an additional power stabilization feed-back system.


title:
New families of supercompact objects and a gravitational mechanism for
  the multiperiodicity of Syg X-1

abstract:
  This paper has been withdrawn by the author due to it contains some errors. A
corrected treatment is presented in further publications of the author.


title: On the Indication from Pioneer 10/11 Data of an Anomalous Acceleration

abstract:
  Hubble's law, which states a linear increase in velocities with distances,
can physically be understood in terms of an acceleration cH. This work proposes
a connection between this "universal" acceleration seen in the solar system and
the anomalous acceleration acting on the Pioneer 10/11 spacecraft, in which the
Hubble constant inferred from Pioneer 10/11 data is ~ 87 km/s/Mpc. Its physical
implication is discussed in relation with Mach's principle.


title: Optimal Mutation Rates on Static Fitness Landscpes

abstract:
  We study the evolution of mutation rates for an asexual population living on
a static fitness landscape, consisting of multiple peaks forming an
evolutionary staircase. The optimal mutation rate is found by maximizing the
diffusion towards higher fitness. Surprisingly the optimal genomic copying
fidelity is given by Q = e^(-1/ln(n)) (where n is the genome length),
independent of all other parameters in the model. Simulations confirm this
theoretical result. We also discuss the relation between the optimal mutation
rate on static and dynamic fitness landscapes.


title: Classical Electrodynamics

abstract:
  Excerpts are presented from a graduate course on Classical Electrodynamics
held during the spring semester of 2000 at the Institute of Physics, Guanajuato
State University, Mexico


title: Coherent transients in optical lattices

abstract:
  We use a method based on optical coherent transients to study the vibrational
coherence lifetimes of atoms trapped in the potential wells of a near-resonant
optical lattice in the oscillating regime. The dependence of the positions and
widths of the vibrational Raman resonances of the coherent transient spectra on
the intensity, detuning, and geometry of the lattice beams is investigated and
the results are compared with theoretical predictions. It is shown that the
principal source of broadening of the vibrational Raman resonances is the
anharmonicity of the light-shift potential wells. We also perform time-resolved
measurements of the vibrational excitation of atoms equilibrating in an optical
lattice.


title: CERN as a Non-School Resource for Science Education

abstract:
  As a large international research laboratory, CERN feels it has a special
responsibility for outreach, and has many activities directed towards schools,
including organized visits, an on-site museum, hands-on experiments, a Summer
intern programme for high-school teachers, lecture series and webcasts. Ongoing
activities and future plans are reviewed, and some ideas stimulated by this
workshop are offered concerning the relevance of CERN's experience to Asia, and
the particular contribution that CERN can make as a non-school resource for
science education.


title:
Analytical treatment of the emittance growth in the main Linacs of
  future linear colliders

abstract:
  In this paper the single and multibunch emittance growths in the main linac
of a linear collider are analytically treated in analogy to the Brownian motion
of a molecule, and the analytical formulae for the emittance growth due to
accelerating structure misalignment errors are obtained by solving Langevin
equation. The same set of formulae is derived also by solving directly
Fokker-Planck equation. Comparisons with numerical simulation results are made
and the agreement is quite well.


title: Analytical estimation of the dynamic apertures of circular accelerators

abstract:
  By considering delta function sextupole, octupole, and decapole perturbations
and using difference action-angle variable equations, we find some useful
analytical formulae for the estimation of the dynamic apertures of circular
accelerators due to single sextupole, single octupole, single decapole (single
2$m$ pole in general). Their combined effects are derived based on the Chirikov
criterion of the onset of stochastic motions. Comparisons with numerical
simulations are made, and the agreement is quite satisfactory. These formulae
have been applied to determine the beam-beam limited dynamic aperture in a
circular collider.


title: Polarization Dependence of Emissivity

abstract:
  We deduce the emissivity of radiation from a metallic surface as a function
of angle and polarization. This effect has found application in the calibration
of detectors for cosmic microwave background radiation.


title: The Precessing Top

abstract:
  I discuss the precession motion of a symmetrical top without the assumption
that its precessional velocity is much smaller than its spin angular velocity.
I derive the general formula for the precessional velocity in an elementary way
and discuss the cases of slow and fast precessions.


title: Suppression of Supercontinuum Generation with Circularly Polarized Light

abstract:
  Controlling a nonlinear process like supercontinuum generation (SG) with the
polarization-state of laser is an important demonstration of laser selectivity.
We show that the threshold for SG and the total amount of supercontinuum
generated depends on incident laser polarization for isotropic samples.
Irrespective of the nature of the samples chosen, SG efficiency decreases as
the incident laser polarization changes from linear to circular and thus,
provides the first experimental demonstration of the suppression of SG with
circularly polarized light. The ratio of the overall SG between the linear and
circular polarization (i.e., measure of suppression) undergoes an intensity
dependent decrease from large initial values to asymptotic limits, irrespective
of samples.


title:
Classical electromagnetism of r^2 spin-orbit interaction and
  nonexistence of magnetic monopoles

abstract:
  We first obtain the electric and magnetic fields corresponding to a
`spin'-orbit classical interaction of a r^2 potential. Assuming that Maxwell
equations hold for these fields, we infer the conditions on the `spin' vector
forbidding magnetic monopoles


title: Coriolis force in Geophysics: an elementary introduction and examples

abstract:
  We show how Geophysics may illustrate and thus improve classical Mechanics
lectures concerning the study of Coriolis force effects. We are then interested
in atmospheric as well as oceanic phenomena we are familiar with, and are for
that reason of pedagogical and practical interest. Our aim is to model them in
a very simple way to bring out the physical phenomena that are involved.


title:
Large Scale-Invariant Fluctuations in Normal Blood Cell Counts: A sign
  of criticality?

abstract:
  All types of blood cells are formed by differentiation from a small
self-maintaining population of pluri-potential stem cells in the bone marrow.
Despite abundant information on the molecular aspects of division,
differentiation, commitment and maturation of these cells, comparatively little
is known about the dynamics of the system as a whole, and how it works to
maintain this complex ``ecology'' in the observed normal ranges throughout
life. Here we report unexpected large, scale-free, fluctuations detected from
the first long-term analysis of the day-to-day variability of a healthy
animal's blood cell counts measured over one thousand days. This
scale-invariance cannot be accounted for by current theoretical models, and
resembles some of the scenarios described for self-organized criticality.

categories: physics.bio-ph cond-mat.stat-mech nlin.AO q-bio


title: The modifications of customary filtrational equation

abstract:
  The usable limits of the customary and relaxational filtrational theories are
considered. The questions of applicable the locality and local thermodynamical
equilibrium principles to depict the nonstationary flows are discussed. The
experimental procedures are proposed to determine the filtrational flows
relaxation times.


title: A Nonstandard Derivation for the Special Theory of Relativity

abstract:
  Using properties of the nonstandard physical world, a new fundamental
derivation for all of the effects of the Special Theory of Relativity is given.
This fundamental derivation removes all the contradictions and logical
difficulties in the original derivation and leads to the fundamental
expressions from which Prokhovnik derives the basic transformations. However,
it is shown that the correct interpretation is completely distinct from
Prokhovnik's. It is shown that the Special Theory effects are but
manifestations of the interaction between our natural world and a nonstandard
substratum. This derivation eliminates the controversy associated with any
physically unexplained universal time dilation and length contraction. It is
shown that there is no such thing as a universal time dilation and length
contraction but, rather, there are alterations in pure numerical quantities
associated with an electromagnetic interaction with a NSP-world substratum.


title:
Localized Beampipe Heating due to $e^-$ Capture and Nuclear Excitation
  in Heavy Ion Colliders

abstract:
  At heavy ion colliders, two major sources of beam loss are expected to be
$e^+e^-$ production, where the $e^-$ is bound to one of the nuclei, and
photonuclear excitation and decay via neutron emission. Both processes alter
the ions charged to mass ratio by well defined amounts, creating beams of
particles with altered magnetic rigidity. These beams will deposit their energy
in a localized region of the accelerator, causing localized heating, The size
of the target region depends on the collider optics. For medium and heavy ions,
at design luminosity at the Large Hadron Collider, local heating may be more
than an order of magnitude higher than expected. This could cause magnet
quenches if the local cooling is inadequate. The altered-rigidity beams will
also produce localized radiation damage. The beams could also be extracted and
used for fixed target experiments.


title: The INT at Age Ten

abstract:
  The history of the Department of Energy's Institute for Nuclear Theory,
located on the campus of the University of Washington, is reviewed on the
occasion of the INT's tenth anniversary.


title: Relativity as the quantum mechanics of space-time measurements

abstract:
  Can a simple microscopic model of space and time demonstrate Special
Relativity as the macroscopic (aggregate) behavior of an ensemble ? The
question will be investigated in three parts. First, it is shown that the
Lorentz transformation formally stems from the First Relativity Postulate (FRP)
{\it alone} if space-time quantization is a fundamental law of physics which
must be included as part of the Postulate. An important corollary, however, is
that when measuring devices which carry the basic units of lengths and time
(e.g. a clock ticking every time quantum) are `moving' uniformly, they appear
to be measuring with larger units. Secondly, such an apparent increase in the
sizes of the quanta can be attributed to extra fluctuations associated with
motion, which are precisely described in terms of a thermally agitated harmonic
oscillator by using a temperature parameter. This provides a stringent
constraint on the microscopic properties of flat space-time: it is an array of
quantized oscillators. Thirdly, since the foregoing development would suggest
that the space-time array of an accelerated frame cannot be in thermal
equilibrium, (i.e. it will have a distribution of temperatures), the approach
is applied to the case of acceleration by the field of {\it any} point object,
which corresponds to a temperature `spike' in the array. It is shown that the
outward transport of energy by phonon conduction implies an inverse-square law
of force at low speeds, and the full Schwarzschild metric at high speeds. A
prediction of the new theory is that when two inertial observers move too fast
relative to each other, or when fields are too strong, anharmonic corrections
will modify effects like time dilation, and will lead to asymmetries which
implies that the FRP may not be sustainable in this extreme limit.


title:
Optical and evaporative cooling of cesium atoms in the gravito-optical
  surface trap

abstract:
  We report on cooling of an atomic cesium gas closely above an evanescent-wave
atom mirror. At high densitities, optical cooling based on inelastic
reflections is found to be limited by a density-dependent excess temperature
and trap loss due to ultracold collisions involving repulsive molecular states.
Nevertheless, very good starting conditions for subsequent evaporative cooling
are obtained. Our first evaporation experiments show a temperature reduction
from 10muK down to 300nK along with a gain in phase-space density of almost two
orders of magnitude.


title:
A Hybrid Algebraic/Schr\"odinger Approach to the 2D Franck-Condon
  Problem

abstract:
  We use recent results regarding the geometry of the U(3) bosonic algebraic
model to motivate a hybrid algebraic-Schr\"odinger approach to the 2D
Franck-Condon problem analogous to 1D approaches. This approach allows one to
analyze bent to linear Franck-Condon transitions of triatomic molecules as well
as clarifies the angular momentum dependance of the Franck-Condon intensities.


title: Algebraic Models: Coordinates, Scales, and Dynamical Symmetries

abstract:
  We discuss the variety of coordinates often used to characterize the coherent
state classical limit of an algebraic model. We show selection of appropriate
coordinates naturally motivates a procedure to generate a single particle
Schr\"odinger hamiltonian which, for low energy states, gives equivalent
results to a bosonic algebraic model to leading order in $N$. The process is
used to study the associated geometries of the dynamical symmetries of U(3). By
demanding that the inner product be preserved in the Schr\"odinger picture we
conclude that different dynamical symmetries correspond to different scales.


title: Off-Diagonal Hyperfine Interaction and Parity Non-conservation in Cesium

abstract:
  We have performed relativistic many-body calculations of the hyperfine
interaction in the $6s$ and $7s$ states of Cs, including the off-diagonal
matrix element. The calculations were used to determine the accuracy of the
semi-empirical formula for the electromagnetic transition amplitude
$<6s|M1|7s>$ induced by the hyperfine interaction. We have found that even
though the contribution of the many-body effects into the matrix elements is
very large, the square root formula $<6s|H_{hfs}|7s > = \sqrt{< 6s|H_{hfs}|6s >
< 7s|H_{hfs}|7s >}$ remains valid to the accuracy of a fraction of $10^{-3}$.
The result for the M1-amplitude is used in the interpretation of the
parity-violation measurement in the $6s-7s$ transition in Cs which claims a
possible deviation from the Standard model.


title: Photon sensitivity of superheated drop at room temperature

abstract:
  It has been reported so far that superheated drop detector made of R-12 at
room temperature are sensitive to neutrons yet insensitive to photons. This
property makes its use as one of the most useful neutron dosimeter. The photon
sensitivity of R12 at room temperature when exposed to 59.54kev photons
obtained from radioactive Am has been noted for the first time in our
laboratory. This discovery is important nt only from the point of view of basic
science but more important to the users of R12 in neutron dosimetry to take
note of this in assessing the neutron dose correctly.


title:
Irradiation of benzene molecules by ion-induced and light-induced
  intense fields

abstract:
  Benzene, with its sea of delocalized $\pi$-electrons in the valence orbitals,
is identified as an example of a class of molecules that enable establishment
of the correspondence between intense ion-induced and laser-light-induced
fields in experiments that probe ionization dynamics in temporal regimes
spanning the attosecond and picosecond ranges.


title: Axioms for Mach's mechanics

abstract:
  We present an axiomatic framework for what we call Mach's mechanics, inspired
on the ideas by A. K. T. Assis and P. Graneau about relational mechanics. We
show that contrarily to what is suggested by these authors, Mach's principle
does not need to be committed with any Weber's like gravitational force.
Actually it is possible to settle an axiomatic framework for non-relativistic
classical particle mechanics which incorporates Mach's principle and is
consistent with any force that obeys the newtonian action-reaction principle.
We make further criticisms concerning relational mechanics.


title: Bell's theorem, entanglement, and common sense

abstract:
  A simple analogy to understand the quantum-mechanical entanglement within
local-realistic world is presented.


title: Universality and individuality in a neural code

abstract:
  The problem of neural coding is to understand how sequences of action
potentials (spikes) are related to sensory stimuli, motor outputs, or
(ultimately) thoughts and intentions. One clear question is whether the same
coding rules are used by different neurons, or by corresponding neurons in
different individuals. We present a quantitative formulation of this problem
using ideas from information theory, and apply this approach to the analysis of
experiments in the fly visual system. We find significant individual
differences in the structure of the code, particularly in the way that temporal
patterns of spikes are used to convey information beyond that available from
variations in spike rate. On the other hand, all the flies in our ensemble
exhibit a high coding efficiency, so that every spike carries the same amount
of information in all the individuals. Thus the neural code has a quantifiable
mixture of individuality and universality.

categories: physics.bio-ph physics.data-an q-bio.NC q-bio.QM


title: Lagrangian Approach to Quantum Mechanics

abstract:
  The Lagrangian approach of Dirac is presented in a complete form. This
suggests to identify the Schr\"{o}dinger equation as the Euler-Lagrange
equation rather than the Hamiltonian operator equation.


title: Melting behavior of large disordered sodium clusters

abstract:
  The melting-like transition in disordered sodium clusters Na_N, with N=92 and
142 is studied by using a first-principles constant-energy molecular dynamics
simulation method. Na_142, whose atoms are distributed in two (surface and
inner) main shells with different radial distances to the center of mass of the
cluster, melts in two steps: the first one, at approx. 130 K, is characterized
by a high intrashell mobility of the atoms, and the second, homogeneous
melting, at approx. 270 K, involves diffusive motion of all the atoms across
the whole cluster volume (both intrashell and intershell displacements are
allowed). On the contrary, the melting of Na_92 proceeds gradually over a very
wide temperature interval, without any abrupt step visible in the thermal or
structural melting indicators. The occurrence of well defined steps in the
melting transition is then shown to be related to the existence of a
distribution of the atoms in shells. Thereby we propose a necessary condition
for a cluster to be considered rigorously amorphouslike (totally disordered),
namely that there are no space regions of the cluster where the local value of
the atomic density is considerably reduced. Na_92 is the only cluster from the
two considered that verifies this condition, so its thermal behavior can be
considered as representative of that expected for amorphous clusters. Na_142,
on the other hand, has a discernible atomic shell structure and should be
considered instead as just partially disordered. The thermal behavior of these
two clusters is also compared to that of icosahedral (totally ordered) sodium
clusters of the same sizes.


title: Resampling Method For Unsupervised Estimation Of Cluster Validity

abstract:
  We introduce a method for validation of results obtained by clustering
analysis of data. The method is based on resampling the available data. A
figure of merit that measures the stability of clustering solutions against
resampling is introduced. Clusters which are stable against resampling give
rise to local maxima of this figure of merit. This is presented first for a
one-dimensional data set, for which an analytic approximation for the figure of
merit is derived and compared with numerical measurements. Next, the
applicability of the method is demonstrated for higher dimensional data,
including gene microarray expression data.


title: Geometry of River Networks I: Scaling, Fluctuations, and Deviations

abstract:
  This article is the first in a series of three papers investigating the
detailed geometry of river networks. Large-scale river networks mark an
important class of two-dimensional branching networks, being not only of
intrinsic interest but also a pervasive natural phenomenon. In the description
of river network structure, scaling laws are uniformly observed. Reported
values of scaling exponents vary suggesting that no unique set of scaling
exponents exists. To improve this current understanding of scaling in river
networks and to provide a fuller description of branching network structure, we
report here a theoretical and empirical study of fluctuations about and
deviations from scaling. We examine data for continent-scale river networks
such as the Mississippi and the Amazon and draw inspiration from a simple model
of directed, random networks. We center our investigations on the scaling of
the length of sub-basin's dominant stream with its area, a characterization of
basin shape known as Hack's law. We generalize this relationship to a joint
probability density and show that fluctuations about scaling are substantial.
We find strong deviations from scaling at small scales which can be explained
by the existence of linear network structure. At intermediate scales, we find
slow drifts in exponent values indicating that scaling is only approximately
obeyed and that universality remains indeterminate. At large scales, we observe
a breakdown in scaling due to decreasing sample space and correlations with
overall basin shape. The extent of approximate scaling is significantly
restricted by these deviations and will not be improved by increases in network
resolution.


title:
Geometry of River Networks II: Distributions of Component Size and
  Number

abstract:
  The structure of a river network may be seen as a discrete set of nested
sub-networks built out of individual stream segments. These network components
are assigned an integral stream order via a hierarchical and discrete ordering
method. Exponential relationships, known as Horton's laws, between stream order
and ensemble-averaged quantities pertaining to network components are observed.
We extend these observations to incorporate fluctuations and all higher moments
by developing functional relationships between distributions. The relationships
determined are drawn from a combination of theoretical analysis, analysis of
real river networks including the Mississippi, Amazon and Nile, and numerical
simulations on a model of directed, random networks. Underlying distributions
of stream segment lengths are identified as exponential. Combinations of these
distributions form single-humped distributions with exponential tails, the sums
of which are in turn shown to give power law distributions of stream lengths.
Distributions of basin area and stream segment frequency are also addressed.
The calculations identify a single length-scale as a measure of size
fluctuations in network components. This article is the second in a series of
three addressing the geometry of river networks.


title:
Geometry of River Networks III: Characterization of Component
  Connectivity

abstract:
  River networks serve as a paradigmatic example of all branching networks.
Essential to understanding the overall structure of river networks is a
knowledge of their detailed architecture. Here we show that sub-branches are
distributed exponentially in size and that they are randomly distributed in
space, thereby completely characterizing the most basic level of river network
description. Specifically, an averaged view of network architecture is first
provided by a proposed self-similarity statement about the scaling of drainage
density, a local measure of stream concentration. This scaling of drainage
density is shown to imply Tokunaga's law, a description of the scaling of side
branch abundance along a given stream, as well as a scaling law for stream
lengths. This establishes the scaling of the length scale associated with
drainage density as the basic signature of self-similarity in river networks.
We then consider fluctuations in drainage density and consequently the numbers
of side branches. Data is analyzed for the Mississippi River basin and a model
of random directed networks. Numbers of side streams are found to follow
exponential distributions as are stream lengths and inter-tributary distances
along streams. Finally, we derive the joint variation of side stream abundance
with stream length, affording a full description of fluctuations in network
structure. Fluctuations in side stream numbers are shown to be a direct result
of fluctuations in stream lengths. This is the last paper in a series of three
on the geometry of river networks.


title: Nonlinear relaxation field in charged systems under high electric fields

abstract:
  The influence of an external electric field on the current in charged systems
is investigated. The results from the classical hierarchy of density matrices
are compared with the results from the quantum kinetic theory. The kinetic
theory yields a systematic treatment of the nonlinear current beyond linear
response. To this end the dynamically screened and field-dependent
Lenard-Balescu equation is integrated analytically and the nonlinear relaxation
field is calculated. The classical linear response result known as Debye -
Onsager relaxation effect is only obtained if asymmetric screening is assumed.
Considering the kinetic equation of one specie the other species have to be
screened dynamically while the screening with the same specie itself has to be
performed statically. Different other approximations are discussed and
compared.

categories: physics.plasm-ph cond-mat.mes-hall cond-mat.str-el nucl-th physics.gen-ph


title: Fiber Bundle Gauge Theories and "Field's Dilemma"

abstract:
  We propose a distinction between the physical and the mathematical parts of
gauge field theories. The main problem we face is to uphold a strong and
meaningful criterion of what is physical. We like to call it "Field's dilemma",
referring to Hartry Field's nominalist proposal which we consider to be
inadaequate. The resolution to the dilemma, we believe, is implicitly provided
by the so-called fiber bundle formalism. We shall demonstrate, in detail, that
the bundle structure underlying modern quantum and gravitational gauge field
theories allows for a genuine distinction between the physically significant
and the merely mathematical parts of these theories.

categories: physics.hist-ph gr-qc hep-th physics.gen-ph quant-ph


title: Mechanical model for gravity

abstract:
  Assuming the existence of a Multidirectional Homogeneous and Constant Shower
of Elementary Particles (MHCSEP) traveling at light speed in space, several
basic laws of physics are derived mainly by geometrical considerations. When
placing two bodies in space, obstruction of the MHCSEP creates an attractive
force among them that coincides, for two bodies, with Newton's law of gravity,
generating a mechanical explanation for gravity.


title:
An orbital-free molecular dynamics study of melting in K_20, K_55, K_92,
  K_142, Rb_55 and Cs_55 clusters

abstract:
  The melting-like transition in potasium clusters K_N, with N=20, 55, 92 and
142, is studied by using an orbital-free density-functional constant-energy
molecular dynamics simulation method, and compared to previous theoretical
results on the melting-like transition in sodium clusters of the same sizes.
Melting in potasium and sodium clusters proceeds in a similar way: a surface
melting stage develops upon heating before the homogeneous melting temperature
is reached. Premelting effects are nevertheless more important and more easily
established in potasium clusters, and the transition regions spread over
temperature intervals which are wider than in the case of sodium. For all the
sizes considered, the percentage melting temperature reduction when passing
from Na to K clusters is substantially larger than in the bulk. Once those two
materials have been compared for a number of different cluster sizes, we study
the melting-like transition in Rb_55 and Cs_55 clusters and make a comparison
with the melting behavior of Na_55 and K_55. As the atomic number increases,
the height of the specific heat peaks decreases, their width increases, and the
melting temperature decreases as in bulk melting, but in a more pronounced way.


title: A Numerical Study of Capillary and Viscous Drainage in Porous Media

abstract:
  This paper reviews recent research results in two-phase flow in porous media
obtained by the authors.


title:
Experiments on the generation of long wavelength edge radiation along
  directions nearly coincident with the axis of a straight section of the
  "Pakhra" synchrotron

abstract:
  Generation of long wavelength edge radiation along directions nearly
coincident with the axes of straight sections of storage rings and synchrotrons
is discussed. The removal of destructive interference from the superimposed
edge radiation patterns of a straight section on the synchrotron "Pakhra" has
been observed experimentally.


title: On the geometry of plasma reactor

abstract:
  It is presented the concept of controled nuclear synthesis in top of cone
formed by rotational dynamic flow of low-temperature plasma.


title: Accurate transition rates for the 5p - 5s transitions in Kr I

abstract:
  Branching fractions were measured for electric dipole transitions from the 5p
upper levels to the 5s levels in neutral krypton atoms. The measurements were
made with a wall-stabilized electric arc and a 2m monochromator for the
spectral lines in the visible, and with a hollow cathode lamp and the NIST
2m-Fourier transform spectrometer for the lines in the near infrared. A
semi-empirical calculation, based on accurately known lifetimes for six upper
levels, was used to calculate lifetimes for which accurate measurements do not
exist. This resulted in a complete set of lifetimes for all 5p levels.
Branching fractions and lifetimes were used to calculate transition rates for
the 5p-5s transitions. The relative uncertainties of the transition rates range
from less than 1% for the strongest lines to about 10% for the weakest lines.
Our data also reveal that most of the previous measurements appear to have been
affected by opacity effects in the light sources.


title:
On the computational capabilities of physical systems part I: the
  impossibility of infallible computation

abstract:
  In this first of two papers, strong limits on the accuracy of physical
computation are established. First it is proven that there cannot be a physical
computer C to which one can pose any and all computational tasks concerning the
physical universe. Next it is proven that no physical computer C can correctly
carry out any computational task in the subset of such tasks that can be posed
to C. As a particular example, this means that there cannot be a physical
computer that can, for any physical system external to that computer, take the
specification of that external system's state as input and then correctly
predict its future state before that future state actually occurs. The results
also mean that there cannot exist an infallible, general-purpose observation
apparatus, and that there cannot be an infallible, general-purpose control
apparatus. These results do not rely on systems that are infinite, and/or
non-classical, and/or obey chaotic dynamics. They also hold even if one uses an
infinitely fast, infinitely dense computer, with computational powers greater
than that of a Turing Machine.

categories: physics.comp-ph cond-mat.stat-mech cs.CC math-ph math.MP physics.gen-ph


title:
On the computational capabilities of physical systems part II:
  relationship with conventional computer science

abstract:
  In the first of this pair of papers, it was proven that that no physical
computer can correctly carry out all computational tasks that can be posed to
it. The generality of this result follows from its use of a novel definition of
computation, ``physical computation''. This second paper of the pair elaborates
the mathematical structure and impossibility results associated with physical
computation. Analogues of Chomsky hierarcy results concerning universal Turing
Machines and the Halting theorem are derived, as are results concerning the
(im)possibility of certain kinds of error-correcting codes. In addition, an
analogue of algorithmic information complexity, ``prediction complexity'', is
elaborated. A task-independent bound is derived on how much the prediction
complexity of a computational task can differ for two different universal
physical computers used to solve that task, a bound similar to the ``encoding''
bound governing how much the algorithm information complexity of a Turing
machine calculation can differ for two universal Turing machines. Finally, it
is proven that either the Hamiltonian of our universe proscribes a certain type
of computation, or prediction complexity is unique (unlike algorithmic
information complexity).

categories: physics.comp-ph cond-mat.stat-mech cs.CC math.OC physics.gen-ph


title: Sub-Doppler resolution with double coherently driving fields

abstract:
  We propose a four-level model where sub-Doppler resolution as well as
enhanced absorption of a weak probe field are realized by using two coherently
driving fields. We show that spectral resolution can be improved by modifying
the coherent fields intensity and frequencies.


title: Superheated drop neutron spectrometer

abstract:
  Superheated drops are known to detect neutrons through the nucleation caused
by the recoil nuclei produced by the interactions of neutrons with the atoms
constituting the superheated liquid molecule. A novel method of finding the
neutron energy from the temperature dependence response of SDD has been
developed. From the equivalence between the dependence of threshold energy for
nucleation on temperature of SDD and the dependence of dE/dx of the recoil ions
with the energy of the neutron, a new method of finding the neutron energy
spectrum of a polychromatic as well as monochromatic neutron source has been
developed.


title: Applying MDL to Learning Best Model Granularity

abstract:
  The Minimum Description Length (MDL) principle is solidly based on a provably
ideal method of inference using Kolmogorov complexity. We test how the theory
behaves in practice on a general problem in model selection: that of learning
the best model granularity. The performance of a model depends critically on
the granularity, for example the choice of precision of the parameters. Too
high precision generally involves modeling of accidental noise and too low
precision may lead to confusion of models that should be distinguished. This
precision is often determined ad hoc. In MDL the best model is the one that
most compresses a two-part code of the data set: this embodies ``Occam's
Razor.'' In two quite different experimental settings the theoretical value
determined using MDL coincides with the best value found experimentally. In the
first experiment the task is to recognize isolated handwritten characters in
one subject's handwriting, irrespective of size and orientation. Based on a new
modification of elastic matching, using multiple prototypes per character, the
optimal prediction rate is predicted for the learned parameter (length of
sampling interval) considered most likely by MDL, which is shown to coincide
with the best value found experimentally. In the second experiment the task is
to model a robot arm with two degrees of freedom using a three layer
feed-forward neural network where we need to determine the number of nodes in
the hidden layer giving best modeling performance. The optimal model (the one
that extrapolizes best on unseen examples) is predicted for the number of nodes
in the hidden layer considered most likely by MDL, which again is found to
coincide with the best value found experimentally.


title: Scaling properties of an inviscid mean-motion fluid model

abstract:
  An inviscid two-dimensional fluid model with nonlinear dispersion that arises
simultaneously in coarse-grained descriptions of the dynamics of the Euler
equation and in the description of non-Newtonian fluids of second grade is
considered. The scaling of the equilibrium states of this model for conserved
energy and enstrophy retains the corresponding scaling for the Euler equations
on the large scales and at the same time greatly deemphasizes the importance of
small scales. This is the first clear demonstration of the beneficial effect of
nonlinear dispersion in the model, and should highlight its utility as a
subgrid model in more realistic situations.


title: Trajectories of light

abstract:
  The trajectories of light are demostrated with experiments made with a
microwave oscilator coupled to a horn antenna and a movable metalic plate along
the radar beam. Two polarizations were made: Linear polarization that produced
double cycloids paths and circular polarization that produced helical paths.
Both trajectories filled the empty space around the trajectories. The new
photon model which is formed by two particles instead of the traditional one,
equations and physical behavior is totally filled.


title: Kinetic Slip Condition, van der Waals Forces, and Dynamic Contact Angle

abstract:
  The profiles of a spreading wetting film are computed taking into account
intermolecular forces and introducing a kinetic slip condition at a molecular
cut-off distance. This eliminates the stress singularity, so that both "true"
and "visible" contact angles are defined unequivocally. The "true" contact
angle at the cut-off distance depends on the slip length as well as on the edge
propagation speed, but not on gravity or asymptotic inclination angle. These
macroscopic factors influence, however, the "visible" contact angle observed in
the interval where the actual film profile departs from the intermediate
asymptotic curve.


title:
Disjoining Potential and Spreading of Thin Liquid Layers in the Diffuse
  Interface Model Coupled to Hydrodynamics

abstract:
  The hydrodynamic phase field model is applied to the problem of film
spreading on a solid surface. The disjoining potential, responsible for
modification of the fluid properties near a three-phase contact line, is
computed from the solvability conditions of the density field equation with
appropriate boundary conditions imposed on the solid support. The equation
describing the motion of a spreading film are derived in the lubrication
approximation. In the case of quasi-equilibrium spreading, is shown that the
correct sharp-interface limit is obtained, and sample solutions are obtained by
numerical integration. It is further shown that evaporation or condensation may
strongly affect the dynamics near the contact line, and accounting for kinetic
retardation of the interphase transport is necessary to build up a consistent
theory.


title:
Quantum-like Chaos in Prime Number Distribution and in Turbulent Fluid
  Flows

abstract:
  Recent studies indicate a close association between the distribution of prime
numbers and quantum mechanical laws governing the subatomic dynamics of quantum
systems such as the electron or the photon. Number theoretical concepts are
intrinsically related to the quantitative description of dynamical systems of
all scales ranging from the microscopic subatomic dynamics to macroscale
turbulent fluid flows such as the atmospheric flows. It is now recognised that
Cantorian fractal spacetime characterise all dynamical systems in nature. A
cell dynamical system model developed by the author shows that the continuum
dynamics of turbulent fluid flows consist of a broadband continuum spectrum of
eddies which follow quantumlike mechanical laws. The model concepts enable to
show that the continuum real number field contains unique structures, namely
prime numbers which are analogous to the dominant eddies in the eddy continuum
in turbulent fluid flows. In this paper it is shown that the prime number
frequency spectrum follows quantumlike mechanical laws.


title:
The Theory of Fractal Time: Field Equations (the Theory of Almost
  Inertial Systems and Modified Lorentz Transformations)

abstract:
  Field equations in four order derivatives with respect to time and space
coordinates based on modified classic relativistic energy of the fractal theory
of time and space are received. It is shown appearing of new spin
characteristics and new fields with imaginary energies .


title:
Does Special Relativity Have Limits of Applicability in the Domain of
  Very Large Energies?

abstract:
  We have shown in the paper that for time with fractional dimensions
(multifractal time theory) there are small domain of velocities $v$ near $v=c$
where SR must be replaced by fractal theory of almost inertial system that do
not contains an infinity and permits moving with arbitrary velocities.


title:
Is the Time a Dimension of an Alien Universe? (this hypothesis gives an
  additional redshift)

abstract:
  On the base of the hypothesis about a nature of the time as a dimension of
alien Universe relation between alteration of time with coordinates
$\frac{\partial t}{\partial x}$ and time {t} offered: $ \frac{\partial t}
{\partial x} = H_{t} t$ . This relation is an analogy of the Habble law in the
time space. The consequence of it is additional redshift $Z_{DT}$ depending on
differences $\tau$ of times existence of the objects with redshift that are
compared ($t_{0}$ is the time existence of more old object):
$Z_{DT}=\frac{1+\frac{\tau}{t_{0}}}{\sqrt{1-(\frac{\tau}{t_{0}}})^{2}}-1$. The
redshift of Arp galaxies may be explained if this relation is used and this
explanation doe's not contradict Arp hypothesis about supernova explosions.
Discussion a possibilities of experimental verification of the hypothesis is
considered.


title:
Characteristics of highly excited diatomic rovibrational spectra and
  slow atomic collisions

abstract:
  We show that the highly excited rovibrational spectra of a diatomic molecule
and the closely related slow atomic collision processes contain more
systematics and require less parameters to characterize than the Rydberg
spectrum of an atom. In the case of a single channel, for example, we show that
a single short-range parameter gives a complete description of slow collisions
for practically all angular momenta, and covers an energy range of hundreds of
millikelvins. The same parameter also describes the highly excited
rovibrational spectra in the threshold region, including states of different
angular momenta. Sample applications and predictions of the theory are
discussed, including comparisons with experiment.


title: Low cloud properties influenced by cosmic rays

abstract:
  The influence of solar variability on climate is currently uncertain. Recent
observations have indicated a possible mechanism via the influence of solar
modulated cosmic rays on global cloud cover. Surprisingly the influence of
solar variability is strongest in low clouds (<= 3km), which points to a
microphysical mechanism involving aerosol formation that is enhanced by
ionisation due to cosmic rays. If confirmed it suggests that the average state
of the Heliosphere is important for climate on Earth.


title: Efficient Dynamic Importance Sampling of Rare Events in One Dimension

abstract:
  Exploiting stochastic path integral theory, we obtain \emph{by simulation}
substantial gains in efficiency for the computation of reaction rates in
one-dimensional, bistable, overdamped stochastic systems. Using a well-defined
measure of efficiency, we compare implementations of ``Dynamic Importance
Sampling'' (DIMS) methods to unbiased simulation. The best DIMS algorithms are
shown to increase efficiency by factors of approximately 20 for a $5 k_B T$
barrier height and 300 for $9 k_B T$, compared to unbiased simulation. The
gains result from close emulation of natural (unbiased), instanton-like
crossing events with artificially decreased waiting times between events that
are corrected for in rate calculations. The artificial crossing events are
generated using the closed-form solution to the most probable crossing event
described by the Onsager-Machlup action. While the best biasing methods require
the second derivative of the potential (resulting from the ``Jacobian'' term in
the action, which is discussed at length), algorithms employing solely the
first derivative do nearly as well. We discuss the importance of
one-dimensional models to larger systems, and suggest extensions to
higher-dimensional systems.


title: Evolution of Biological Complexity

abstract:
  In order to make a case for or against a trend in the evolution of complexity
in biological evolution, complexity needs to be both rigorously defined and
measurable. A recent information-theoretic (but intuitively evident) definition
identifies genomic complexity with the amount of information a sequence stores
about its environment. We investigate the evolution of genomic complexity in
populations of digital organisms and monitor in detail the evolutionary
transitions that increase complexity. We show that because natural selection
forces genomes to behave as a natural ``Maxwell Demon'', within a fixed
environment genomic complexity is forced to increase.

categories: physics.bio-ph cond-mat.stat-mech cs.CC nlin.AO physics.data-an q-bio.PE


title:
Solitary coherent structures in viscoelastic shear flow: computation and
  mechanism

abstract:
  Starting from stationary bifurcations in Couette-Dean flow, we compute
nontrivial stationary solutions in inertialess viscoelastic circular Couette
flow. These solutions are strongly localized vortex pairs, exist at arbitrarily
large wavelengths, and show hysteresis in the Weissenberg number, similar to
experimentally observed ``diwhirl'' patterns. Based on the computed velocity
and stress fields, we elucidate a heuristic, fully nonlinear mechanism for
these flows. We propose that these localized, fully nonlinear structures
comprise fundamental building blocks for complex spatiotemporal dynamics in the
flow of elastic liquids.


title: Coherence in a simple network: Implication for brain function

abstract:
  In a many body system, constituents interact with each other, forming a
recursive pattern of interaction and giving rise to many interesting phenomena.
Based upon concepts of the modern many body theory, a model for a generic many
body system is developed. A novel approach is proposed to investigate the
general features in such a system. An interesting phase transition in the
system is found. Possible link to brain dynamics is discussed. It is shown how
some of the basic brain processes, such as learning and memory, find therein a
natural explanation.


title:
On the Arbitrary Choice Regarding which Inertial Reference Frame is
  "Stationary" and which is "Moving" in the Special Theory of Relativity

abstract:
  Einstein's argument on the relativity of simultaneity itself is the first
result of the special theory of relativity. The nature of this result is
explored, and implications of this result for the structure and functioning of
the physical world found in the special theory are discussed.


title: Atom Interference using microfabricated structures

abstract:
  Atom density profile arising in the atomic beam after passing through the one
or two microfabricated structures (MS) is considered. Two limiting cases the
beam with large and small angular divergence are considered. An equivalence of
the considerations based on the Fresnel-Kirchhoff theory of diffraction and on
the atomic recoil-effect is established. Higher order gratings' profiles
produced in the collinear beam owing to the atomic Talbot effect are
calculated. For an atomic beam with large angular divergence, two regimes of
atoms' scattering off the MS, classical and quantum, are analyzed. For
classical scattering from two MSs, the atomic density periodic modulation
focusses at the echo points owing to the shadow effect. Elaborated simple
geometric interpretation of the echo-effect. Dephasing-rephasing processes
induced by two MSs having rational ratio of their periods are fully classified.
Positions and profiles of the higher order gratings are calculated. Gratings'
deformations caused by the quantum scattering are included. In this case,
corresponding to the atomic Talbot-Lau effect, for a distance between fields
equal to 1/n part of the Talbot distance, one compresses n times the grating
caused by the shadow effect.


title: Classical double ionization of atoms in strong fields

abstract:
  Recent high resolution measurements of the momenta of two electrons emitted
from Argon atoms in a strong laser field show a strong preference for the
outgoing electrons to have similar momenta and to be ejected in the same
direction along the field. We discuss the final stages of this process in a
classical model in the spirit of Wanniers approach to double ionization after
electron impact. Starting from an intermediate state of high but negative
energy the field opens up a channel through which both electrons can escape.
Near the threshold for this process Coulomb repulsion favors an escape with the
electron momenta and positions symmetric with respect to the electric field
axis. Classical trajectory simulations within this symmetry subspace account
for most features of the observed momentum distribution.


title:
Damage of cellular material under simultaneous application of pressure
  and pulsed electric field

abstract:
  Influence of pulsed electric field (PEF) simultaneous to pressure treatment
on moisture expression from fine-cut cellular raw material has been
investigated. Dependencies of specific conductivity $\sigma$, liquid yield $Y$,
instantaneous flow rate $v$ and qualitative juice characteristics at different
modes of PEF treatment are discussed. Three main consolidation phases were
observed in a case of mechanical expression. A unified approach is proposed for
liquid yield data analysis allowing to reduce the data scattering caused by
differences in the quality of samples. Simultaneous application of pressure and
PEF treatment allows to reveal a passive form of electrical damage. Pressure
provokes the damage of defected cells, enhances diffusion migration of moisture
in porous cellular material and depresses the cell resealing processes. PEF
application at a moment when a sample specific electrical conductivity reaches
minimum and pressure achieves its constant value seemed to be the most optimal.


title: Atomic micromotion and geometric forces in a triaxial magnetic trap

abstract:
  Non-adiabatic motion of Bose-Einstein condensates of rubidium atoms arising
from the dynamical nature of a time-orbiting-potential (TOP) trap was observed
experimentally. The orbital micromotion of the condensate in velocity space at
the frequency of the rotating bias field of the TOP was detected by a
time-of-flight method. A dependence of the equilibrium position of the atoms on
the sense of rotation of the bias field was observed. We have compared our
experimental findings with numerical simulations. The nonadiabatic following of
the atomic spin in the trap rotating magnetic field produces geometric forces
acting on the trapped atoms.


title: Long-range interaction of two metastable rare-gas atoms

abstract:
  We present semiempirical calculations of long-range van der Waals
interactions for two interacting metastable rare-gas atoms Ne through Xe.
Dispersion coefficients $C_6$ are obtained for homonuclear molecular potentials
asymptotically connecting to the $ns(3/2)_{2} + ns(3/2)_{2}$ atomic states. The
estimated uncertainty of the calculated $C_6$ dispersion coefficients is 4%.


title:
Modulation Instability and Pattern Formation in Spatially Incoherent
  Light Beams

abstract:
  We present the first experimental observation of modulation instability of
partially spatially incoherent light beams in non-instantaneous nonlinear
media. We show that even in such a nonlinear partially coherent system (of
weakly-correlated particles) patterns can form spontaneously. Incoherent MI
occurs above a specific threshold that depends on the beams' coherence
properties (correlation distance), and leads to a periodic train of
one-dimensional (1D) filaments. At a higher value of nonlinearity, incoherent
MI displays a two-dimensional (2D) instability and leads to self-ordered arrays
of light spots.


title:
A gentle introduction to the foundations of classical electrodynamics:
  The meaning of the excitations (D,H) and the field strengths (E, B)

abstract:
  The axiomatic structure of the electromagnetic theory is outlined. We will
base classical electrodynamics on (1) electric charge conservation, (2) the
Lorentz force, (3) magnetic flux conservation, and (4) on the Maxwell-Lorentz
spacetime relations. This yields the Maxwell equations. The consequences will
be drawn, inter alia, for the interpretation and the dimension of the electric
and magnetic fields.


title: Beam-Generated Detector Backgrounds at CESR

abstract:
  The CESR/CLEO Phase II interaction region is described. The operational
experience with beam-generated detector backgrounds is reviewed. The status of
our understanding of beam-generated detector backgrounds at CESR is described
and comparisons of background measurements with simulation predictions are
presented.


title: Radiating dipoles in photonic crystals

abstract:
  The radiation dynamics of a dipole antenna embedded in a Photonic Crystal are
modeled by an initially excited harmonic oscillator coupled to a non--Markovian
bath of harmonic oscillators representing the colored electromagnetic vacuum
within the crystal. Realistic coupling constants based on the natural modes of
the Photonic Crystal, i.e., Bloch waves and their associated dispersion
relation, are derived. For simple model systems, well-known results such as
decay times and emission spectra are reproduced. This approach enables direct
incorporation of realistic band structure computations into studies of
radiative emission from atoms and molecules within photonic crystals. We
therefore provide a predictive and interpretative tool for experiments in both
the microwave and optical regimes.

categories: physics.class-ph cond-mat physics.optics quant-ph


title:
Electron-hole pairs multiquantum generation mechanizm in the process of
  excitation of ZnSCdS-Cu by an atomic hydrogen

abstract:
  The luminecsence of ZnSCdS-Cu phosphors of various CdS consentration (0-40%)
is under investigation. The luminescence was exited by hydrogen atoms during
adsorbtion of thermal energy during adsorbtion and impact
recombination-heterogeneous chemiluminenscence(HCL) are discussed. The monotone
lowering of the conductivity zone bottom level with respect to the valence zone
ceiling (from 3,7 eV to 3,2 eV) with increasing CdS concentration (from 0 -
40%). HCL intensity with respect to CdS (from 3,7 eV to 3,2 eV)- concentration
($E_g$)grows rapidly. The dependence of HCL intensity on the forbidden zone
width can be explained by the action of electron - hole pairs multiquontum
generation mechanism.


title: Spectral Dependence of Polarized Radiation due to Spatial Correlations

abstract:
  We study the polarization of light emitted by spatially correlated sources.
We show that in general polarization acquires nontrivial spectral dependence
due to spatial correlations. The spectral dependence is found to be absent only
for a special class of sources where the correlation length scales as the
wavelength of light. We further study the cross correlations between two
spatially distinct points that are generated due to propagation. It is found
that such cross correlation leads to sufficiently strong spectral dependence of
polarization which can be measured experimentally.


title: Physics of Aberration rather than Special Relativity

abstract:
  A phenomenological explanation is presented for the physics of aberration,
which is in contrast with special relativity physics. The effect of relativity
is identified with an effect due to the velocity of observation being affected
by the velocity of a moving particle. In contrast with the currently accepted
view, it is demonstrated that the classical concepts of time and simultaneity
are natural for describing relativistic phenomena.


title: Optical Approach to Gravitational Redshift

abstract:
  An optical approach begins by interpreting the gravitational redshift
resulting to a change in the relative velocity of light due to the medium of
propagation in the gravitational field. The discussion continues by pointing
out an agreement in structure between the equation for rays in geometrical
optics and the geodesic equation of general relativity. From their comparison
we learn that the path of rays should be given by the relation
$ds^2=n^2(r)dr^2+r^2d\theta^2$, not by $ds^2=dr^2+r^2d\theta^2$, in a medium
with spherical symmetry of refractive index $n(r)$. The development of an
optical analogy suggests introducing $n^2(r)$ in place of $g_{rr}$ as an
optical version of the Schwarzschild metric. In form and content, $n^2(r)$ is
different from $g_{rr}$. The optical point of view replaces the
general-relativity explanations in terms of time and gravitation.


title: Polarized Protons in HERA

abstract:
  Polarized proton beams at HERA can currently only be produced by extracting a
beam from a polarized source and then accelerating it in the three synchrotrons
at DESY. In this paper, the processes which can depolarize a proton beam in
circular accelerators are explained, devices which could avoid this
depolarization in the DESY accelerator chain are described, and specific
problems which become important at the high energies of HERA are mentioned. At
HERA's high energies, spin motion cannot be accurately described with the
isolated resonance model which has been successfully used for lower energy
rings. To illustrate the principles of more accurate simulations, the invariant
spin field is introduced to describe the equilibrium polarization state of a
beam and the changes during acceleration. It will be shown how linearized spin
motion leads to a computationally quick approximation for the invariant spin
field and how to amend this with more time consuming but accurate
non-perturbative computations. Analysis with these techniques has allowed us to
establish optimal Siberian Snake schemes for HERA.


title: Successive approximations for charged particle motion

abstract:
  Single particle dynamics in electron microscopes, ion or electron
lithographic instruments, particle accelerators, and particle spectrographs is
described by weakly nonlinear ordinary differential equations. Therefore, the
linear part of the equation of motion is usually solved and the nonlinear
effects are then found in successive order by iteration methods. A Hamiltonian
nature of these equations can lead to simplified computations of particle
transport through an optical device when a suitable computational method is
used. Many ingenious microscopic and lithographic devices were found by H. Rose
and his group due to the simple structure of the eikonal method. In the area of
accelerator physics the eikonal method has never become popular. Here I will
therefore generalize the eikonal method and derive it from a Hamiltonian quite
familiar to the accelerator physics community. With the event of high energy
polarized electron beams and plans for high energy proton beams, nonlinear
effects in spin motion have become important in high energy accelerators. I
will introduce a successive approximation for the nonlinear effects in the
coupled spin and orbit motion of charged particles which resembles some of the
simplifications resulting from the eikonal method for the pure orbit motion.


title: Singularities in kinetic theory

abstract:
  It is revealed that distribution functions of practical gases relate to
singularities and such singularities can, with molecular motion, spread to the
entire region of interest. It is also shown that even common continuous
distribution functions involve a similar quasi-discontinuity difficulty.


title:
First Observation of Self-Amplified Spontaneous Emission in a
  Free-Electron Laser at 109 nm Wavelength

abstract:
  We present the first observation of Self-Amplified Spontaneous Emission
(SASE) in a free-electron laser (FEL) in the Vacuum Ultraviolet regime at 109
nm wavelength (11 eV). The observed free-electron laser gain (approx. 3000) and
the radiation characteristics, such as dependency on bunch charge, angular
distribution, spectral width and intensity fluctuations all corroborate the
existing models for SASE FELs.


title:
Phase Mixing of Nonlinear Plasma Oscillations in an Arbitrary Mass Ratio
  Cold Plasma

abstract:
  Nonlinear plasma oscillations in an arbitrary mass ratio cold plasma have
been studied using 1-D particle-in-cell simulation. In contrast to earlier work
for infinitely massive ion plasmas it has been found that the oscillations
phase mix away at any amplitude and that the rate at which phase mixing occurs,
depends on the mass ratio ($\Delta = m_{-}/m_{+}$) and the amplitude. A
perturbation theoretic calculation carried upto third order predicts that the
normalized phase mixing time $\omega_{p-} t_{mix}$ depends on the amplitude $A$
and the mass ratio $\Delta$ as $\sim [(A^{2}/24)(\Delta/\sqrt{1 +
\Delta})]^{-1/3}$. We have confirmed this scaling in our simulations and
conclude that stable non-linear oscillations which never phase mix, exist only
for the ideal case with $\Delta = 0.0$ and $A < 0.5$. These cold plasma results
may have direct relevance to recent experiments on superintense laser beam
plasma interactions with applications to particle acceleration, fast ignitor
concept etc.


title: A new approach to study energy transfer in turbulence

abstract:
  The unit of nonlinear interaction in Navier-Stokes and the
Magnetohydrodynamic (MHD) equations is a wavenumber triad ({\bf k,p,q})
satisfying ${\bf k+p+q=0}$. The expression for the combined energy transfer
from two of these wavenumbers to the third wavenumber is known. In this paper
we introduce the idea of an effective energy transfer between a pair of modes
through the mediation of the third mode and then find an expression for it. In
fluid turbulence, energy transfer takes place between a pair of velocity modes,
whereas in MHD turbulence energy transfer takes places between (1) a pair of
velocity modes, (2) a pair of magnetic modes, and (3) between a velocity and a
magnetic mode in a triad. In this paper we have obtained the expression for
each of these transfers. We also show how the effective mode-to-mode energy
transfer rate can be utilised to study energy cascades and shell-to-shell
energy transfer rates.


title:
Multielectron ionization of atoms in strong fields: Classical analysis
  in symmetric subspace

abstract:
  We consider the final stage of multiple ionization of atoms in a strong
linearly polarized laser field within a classical model. We propose that
non-sequential multiple ionization is dominated by symmetric escape from a
highly excited intermediate complex. For a configuration of N electrons with
C_Nv symmetry in a plane perpendicular to the electric field we analyze the
classical motion in phase space and discuss the final momentum distribution
parallel and perpendicular to the polarization axis. The results are in good
agreement with recent experiment of multiple ionization in Ne.


title: The problem of friction in two-dimensional relative motion

abstract:
  We analyse a mechanical system in two-dimensional relative motion with
friction. Although the system is simple, the peculiar interplay between two
kinetic friction forces and gravity leads to the wide range of admissible
solutions exceeding most intuitive expectations. In particular, the strong
qualitative dependence between behaviour of the system, boundary conditions and
parameters involved in its description is emphasised. The problem is intended
to be discussed in theoretical framework and might be of interest for physics
and mechanics students as well as for physics teachers.