title: Possible Gigantic Variations on the Width of Viscoelastic Fingers

abstract:
  We analyze the effect of frequency on the width of a single finger displacing
a viscoelastic fluid. We derive a generalized Darcy's law in the frequency
domain for a linear viscoelastic fluid flowing in a Hele Shaw cell. This leads
to an analytic expression for the dynamic permeability that has maxima which
are several orders of magnitude larger than the static permeability. We then
follow an argument of de Gennes to obtain the smallest possible finger width
when viscoelasticity is important. Using this, and a conservation law, we
obtain a lowest bound for the width of a single finger displacing a
viscoelastic fluid. Our results indicate that when a small amplitude signal of
the frequency that maximizes the permeability is overimposed to a constant
pressure drop, gigantic variations are obtained for the finger width.


title: The Hydraulic Jump In Two Dimensions

abstract:
  The first quantitative calculation of the hydraulic jump was carried out only
a few years ago by Bohr et al. Since it is the only calculation of the jump, we
have analysed it from a slightly different point of view.Our results are
similar to those of Bohr et.al.


title: Linking Ultracold Polar Molecules

abstract:
  We predict that pairs of polar molecules can be weakly bound together in an
ultracold environment, provided that a dc electric field is present. The field
that links the molecules together also strongly influences the basic properties
of the resulting dimer, such as its binding energy and predissociation
lifetime. Because of their long-range character these dimers will be useful in
disentangling cold collision dynamics of polar molecules. As an example, we
estimate the microwave photoassociation yield for OH-OH cold collisions.


title: Channeling of high energy beams in nanotubes

abstract:
  We present simulations of particle beam channeling in carbon nanotubes and
evaluate the possibilities for experimental observation of channeling effect in
straight and bent nanotubes at IHEP and LNF. Different particle species are
considered: protons of 1.3 and 70 GeV, and positrons of 0.5 GeV. Predictions
are made for the experiments, with analysis of requirements on the quality of
nanosamples and resolution of the experimental set-up. Based on Monte Carlo
simulations, the capabilities of nanotube channeling technique for particle
beam steering are discussed.


title:
Local-Ether Wave Equation of Electric Field and Interferometry
  Experiments with Moving Medium and Path

abstract:
  Recently, we have presented the local-ether model, whereby the propagation of
earthbound waves is supposed to be referred uniquely to a geostationary
inertial frame. Further, in order to comply with this propagation model, the
modified Lorentz force law is developed. Thereby, the corresponding wave
equations of potentials and fields are derived in this investigation. It is
shown that the local-ether wave equation of electric field can account for
various precision interferometry experiments in a consistent way, including the
one-way-link experiment with a geostationary fiber, the Sagnac rotating-loop
experiment with a comoving or a geostationary dielectric medium, and Fizeau's
experiment with a moving dielectric medium in a geostationary interferometer.
These experiments together then provide a support for the local-ether wave
equation. Meanwhile, some other phenomena are predicted, which provide a means
to test its validity.


title:
Modifications of Schr\"{o}dinger's Equation Complying with the Effect of
  Earth's Rotation on Quantum Energy in Atoms and with the Electromagnetic
  Force

abstract:
  Recently, we have presented a local-ether wave equation incorporating a
nature frequency and the electric scalar potential, from which the
speed-dependences in the angular frequency and wavelength of matter wave, in
the mass of particle, and in the energy of quantum states are derived. These
relations look like the postulates of de Broglie and the Lorentz mass-variation
law, except that the particle speed is referred specifically to a geocentric
inertial frame and hence incorporates earth's rotation for earthbound
particles. Further, the wave equation is extended by connecting the scalar
potential to the augmentation operator which is associated with a velocity
difference between involved particles. Then the electromagnetic force law is
derived, which under some ordinary conditions reduces to the modified Lorentz
force law. In this investigation, the interaction of atoms with electromagnetic
radiation is explored. Then it is shown that the time evolution equation
derived from the wave equation is substantially identical to Schr\"{o}dinger's
equation incorporating the vector potential, if the latter is observed in the
atom frame and if the source generating the vector potential is electrically
neutralized, as in common practice.


title:
Resonant Absorption between Moving Atoms due to Doppler Frequency Shift
  and Quantum Energy Variation

abstract:
  By taking both the Doppler frequency shift for electromagnetic wave and the
quantum energy variation of matter wave into consideration, a
resonant-absorption condition based on the local-ether wave equation is
presented to account for a variety of phenomena consistently, including the
Ives-Stilwell experiment, the output frequency from ammonia masers, and the
M\"{o}ssbauer rotor experiment. It is found that in the resonant-absorption
condition, the major term associated with the laboratory velocity is a
dot-product term between this velocity and that of the emitting or absorbing
atom. This term appears both in the Doppler frequency shift and the transition
frequency variation and then cancels out. Thereby, the experimental results can
be independent of the laboratory velocity and hence comply with Galilean
relativity, despite the restriction that the involved velocities are referred
specifically to the local-ether frame. However, by examining the
resonant-absorption condition in the M\"{o}ssbauer rotor experiment to a higher
order, it is found that Galilean relativity breaks down.


title:
Reinterpretation of Matter-Wave Interference Experiments Based on the
  Local-Ether Wave Equation

abstract:
  Based on the local-ether wave equation for free particle, the dispersion of
matter wave is examined. From the dispersion relation, the angular frequency
and wavelength of matter wave are derived. These formulas look like the
postulates of de Broglie in conjunction with the Lorentz mass-variation law.
However, the fundamental difference is that for terrestrial particles their
speeds are referred specifically to a geocentric inertial frame and hence
incorporate the speed due to earth's rotation. Thus the local-ether model
predicts an east-west directional anisotropy both in mass and wavelength.
Meanwhile, in spite of the restriction on reference frame, the local-ether
model can account for the matter-wave interference experiments of the Bragg
reflection and the Sagnac effect. For electron wave, the effects of earth's
rotation are negligible and the derived Bragg angle is actually in accord with
the Davisson-Germer experiment, as examined within the present precision. On
the other hand, the local-ether model leads to a directional anisotropy in the
Bragg angle in neutron diffraction. The predicted anisotropy due to earth's
rotation then provide a means to test the local-ether wave equation.


title: Wakefield Band Partitioning In Linac Structures

abstract:
  In the NLC project multiple bunches of electrons and positrons will be
accelerated initially to a centre of mass of 500 GeV and later to 1 TeV or
more. In the process of accelerating 192 bunches within a pulse train,
wakefields are excited which kick the trailing bunches off axis and can cause
luminosity dilution and BBU (Beam Break Up). Several structures to damp the
wakefield have been designed and tested at SLAC and KEK and these have been
found to successfully damp the wakefield [1]. However, these 2pi/3 structures
suffered from electrical breakdown and this has prompted us to explore lower
group velocity structures operating at higher fundamental mode phase advances.
The wakefield partitioning amongst the bands has been found to change markedly
with increased phase advance. Here we report on general trends in the kick
factor and associated wakefield band partitioning in dipole bands as a function
of phase advance of the synchronous mode in linacs. These results are
applicable to both TW (travelling wave) and SW (standing wave) structures [1]
R.M. Jones et al, PAC99, also SLAC-PUB-8103


title: Measuring the Earth with Traceroute

abstract:
  The traceroute utility on any computer connected to the Internet can be used
to record the roundtrip time for small Internet packets between major Internet
traffic hubs. Some of the routes include transmission over transoceanic fiber
optic cable. We report on traceroute's use by students to quickly and easily
estimate the size of the Earth. This is an inexpensive way to involve
introductory physics students in a hands-on use of scientific notation and to
teach them about systematics in data.


title: Precision measurement of the metastable 3P2 lifetime of neon

abstract:
  The lifetime of the metastable 3P2 state of neon has been determined to
14.70(13) s (decay rate 0.06801(62) 1/s) by measuring the decay in fluorescence
of an ensemble of Ne-20 atoms trapped in a magneto-optical trap (MOT). Due to
low background gas pressure p < 5 10^-11 mbar and low relative excitation to
the 3D3 state (0.5% excitation probability) operation only small corrections
have to be included in the lifetime extrapolation. Together with a careful
analysis of residual loss mechanisms in the MOT a lifetime determination to
high precision is achieved.


title: Dynamical Monte Carlo method for stochastic epidemic models

abstract:
  In this work we introduce a new approach to Dynamical Monte Carlo methods to
simulate markovian processes. We apply this approach to formulate and study an
epidemic generalized SIRS model. The results are in excellent agreement with
the fourth order Runge-Kutta method in a region of deterministic solution.
Introducing local stochastic interactions, the Runge-Kutta method is no longer
applicable. Thus, we solve the system described by a set of stochastic
differential equations by a Dynamical Monte Carlo technique and check the
solutions self-consistently with a stochastic version of the Euler method. We
also analyzed the results under the herd-immunity concept.


title:
Proton Irradiation Experiment for the X-ray Charge-Coupled Devices of
  the Monitor of All-sky X-ray Image mission onboard the International Space
  Station: I. Experimental Setup and Measurement of the Charge Transfer
  Inefficiency

abstract:
  We have investigated the radiation damage effects on a CCD to be employed in
the Japanese X-ray astronomy mission including the Monitor of All-sky X-ray
Image (MAXI) onboard the International Space Station (ISS). Since low energy
protons release their energy mainly at the charge transfer channel, resulting a
decrease of the charge transfer efficiency, we thus focused on the low energy
protons in our experiments. A 171 keV to 3.91 MeV proton beam was irradiated to
a given device. We measured the degradation of the charge transfer inefficiency
(CTI) as a function of incremental fluence. A 292 keV proton beam degraded the
CTI most seriously. Taking into account the proton energy dependence of the
CTI, we confirmed that the transfer channel has the lowest radiation tolerance.
We have also developed the different device architectures to reduce the
radiation damage in orbit. Among them, the ``notch'' CCD, in which the buried
channel implant concentration is increased, resulting in a deeper potential
well than outside, has three times higher radiation tolerance than that of the
normal CCD. We then estimated the charge transfer inefficiency of the CCD in
the orbit of ISS, considering the proton energy spectrum. The CTI value is
estimated to be 1.1e-5 per each transfer after two years of mission life in the
worse case analysis if the highest radiation-tolerant device is employed. This
value is well within the acceptable limit and we have confirmed the high
radiation-tolerance of CCDs for the MAXI mission.


title:
Reaction-diffusion dynamics: confrontation between theory and experiment
  in a microfluidic reactor

abstract:
  We confront, quantitatively, the theoretical description of the
reaction-diffusion of a second order reaction to experiment. The reaction at
work is \ca/CaGreen, and the reactor is a T-shaped microchannel, 10 $\mu$m
deep, 200 $\mu$m wide, and 2 cm long. The experimental measurements are
compared with the two-dimensional numerical simulation of the
reaction-diffusion equations. We find good agreement between theory and
experiment. From this study, one may propose a method of measurement of various
quantities, such as the kinetic rate of the reaction, in conditions yet
inaccessible to conventional methods.


title:
Low-Energy Electron-Beam Diagnostics Based on the Optical Transition
  Radiation

abstract:
  A possibility of a few MeV electron beam diagnostics (Lorentz factor ~ 10)
using polarization characteristics of the optical transition radiation (OTR)
have been considered. Determinaton of the electron beam divergence have been
performed with technique based on the OTR measurements. The technique is based
on measuring the ratio R=Imin/Imax, where Imin(Imax) is the photon yield in the
minimum (maximum) of OTR angular distribution. It is shown that the value of R
can be obtained also from the measurement of the so-called psi-scan of the OTR
yield registered by a fixed detector with the aperture < gamma^(-1) by varying
the target tilt angle with respect to the electron-beam. The experiment curried
out at 6.1 MeV Tomsk microtron has demonstrated the feasibility of the
technique proposed.


title:
Synchrotron radiation contributions to optical diffraction radiation
  measurements

abstract:
  If we try to measure the backward optical diffraction radiation (BODR) of
high energy electrons from a conductive slit or a semi infinitive plate, the
electron beam will pass thru the bending or steering magnets or magnet lenses
before striking the target. The synchrotron radiation (SR) from these magnets
can obscure the BODR measurements. An analysis of the properties of SR from
these magnets is in this paper presented. A model based on the modified Lenar
Wikherd potentials was created, and the SR angular distribution from
relativistic electrons in bending and steering magnets for different conditions
of radiation in the optical region was calculated. The analysis shows, that for
the conditions of the KEK ATF extraction line, the intensity of SR exceeds that
of the backward optical transition radiation (BOTR) from the conducting
targets, and it is much lager than the intensity of the BODR. The SR intensity
from the steering magnets depends on its tuning and may be comparable to BOTR.
Thus, these results it is seen, that the problem of separation of the BODR and
SR in the BODR measurements is important. Two methods resolving of this problem
is in this article suggested.


title:
Investigation of resonant polarization radiation of relativistic
  electrons in gratings at small angles

abstract:
  The Resonant Optical Polarization Radiation (ROPR) in the Smith-Purcell
geometry and the one from the inclined grating at the Tomsk synchrotron and
6-MeV microtron have been investigated. The polarization radiation was observed
at 4.2o from the 200 MeV electron beam and at 5o from the 6.2 MeV electron
beam. Two methods of measurement of ROPR maxima in these two cases have been
used. In the first case (the experiment on synchrotron) we have fixed the
wavelength of radiation using an optical filter; the orientation dependence of
this radiation was measured. In this dependence we have observed two peaks of
radiation from electrons in gold foil grating of 0.1 mm period. The first large
peak is a zeroth order peak in direction of specular reflection, and the second
one is the 1-st order peak of resonant polarization radiation. In the
experiment on microtron the spectra of ROPR from aluminum foil strip grating of
0.2 mm period in the Smith-Purcell geometry were measured, and the peak of the
1-st order Smith-Purcell radiation in these spectra was observed. The
comparison of data obtained with the simulation results has been performed.


title:
Solving the riddle of the bright mismatches: hybridization in
  oligonucleotide arrays

abstract:
  HDONA technology is predicated on two ideas. First, the differential between
high-affinity (perfect match, PM) and lower-affinity (mismatch, MM) probes is
used to minimize cross-hybridization. Second, several short probes along the
transcript are combined, introducing redundancy. Both ideas have shown problems
in practice: MMs are often brighter than PMs, and it is hard to combine the
pairs because their brightness often spans decades. Previous analysis suggested
these problems were sequence-related; publication of the probe sequences has
permitted us an in-depth study of this issue. Our results suggest that
fluorescently labeling the nucleotides interferes with mRNA binding, causing a
catch-22 since, to be detected, the target mRNA must both glow and stick to its
probe: without labels it cannot be seen even if bound, while with too many it
won't bind. We show that this conflict causes much of the complexity of HDONA
raw data, suggesting that an accurate physical understanding of hybridization
by incorporating sequence information is necessary to perfect microarray
analysis.


title:
Research News : Direct observation of neutrino oscillations at the
  Sudbury Neutrino Observatory

abstract:
  A brief description of the path-breaking evidence for the observation of
neutrino oscillations at the Sudbury Neutrino Observatory is presented and the
experimental principles and theory thereof are briefly discussed.


title: X-waves Generated at Second Harmonic

abstract:
  The process of optical frequency doubling can lead, in the undepleted regime,
to the generation of a X-wave envelope with group velocity locked to the pump
beam. Its parameters and its angular spectrum, are directly related to the
zero- and first-order dispersive features of the nonlinear process. This
constitutes a novel mechanism for spatio-temporal localization of light.


title: Some notes on ideology of waves in plasmas

abstract:
  Our last three papers provide an occasion to make some brief notes on
ideology of waves in plasmas and to rehabilitate Vlasov prescription to
calculate relevant logarithmically divergent integrals in the principal value
sense. In this approach asymptotical solutions of plasma oscillations are
selected according to self-consistent boundary physical conditions. Landau
damping is absent in this case by definition. Boundary electrical field
together with conditions of absence of unphysical backward and kinematical
waves define single-valued dependence of boundary distribution function on
electron velocity \vec{v} in the case of transversal waves and on the surface
break of the normal electrical field in the case of longitudinal oscillations.
We have proposed physically more justified modified iteration procedure of
collisional damping calculation and demonstrated some results of damping
decrements calculations in a low-collision electron-ion plasma. Dispersion
smearing of both longitudinal and transversal high-frequency waves, for which
the smearing decrement \delta_x is proportional to
\Delta\omega/(\omega\sqrt{\omega^2-\omega_L^2}), might be the main cause of
waves amplitude damping in collisionless plasmas imitating Landau damping.


title: Enrichment of CH3F nuclear spin isomers by resonant microwave radiation

abstract:
  Theoretical model of the coherent control of nuclear spin isomers by
microwave radiation has been developed. Model accounts the M-degeneracy of
molecular states and molecular center-of-mass motion. The model has been
applied to the 13CH3F molecules. Microwave radiation excites the para state
(J=11,K=1) which is mixed by the nuclear spin-spin interaction with the ortho
state (9,3). Dependencies of the isomer enrichment and conversion rates on the
radiation frequency have been calculated. Both spectra consist of two
resonances situated at the centers of allowed and forbidden (by nuclear spin)
transitions in the molecule. Larger enrichment, up to 7%, can be produced by
strong radiation resonant to the forbidden transition. The spin conversion rate
can be increased by 2 orders of magnitude at this resonance.


title: Equilibrium correlations in a model for multidimensional epistasis

abstract:
  We investigate a statistical model for multidimensional epistasis. The
genotype is devided into subsequences, and within each subsequence mutations
which occur in a prescribed order are beneficial. The bit-string model used to
represent the genotype, may be cast in the form of a ferromagnetic Ising model
with a staggered field. We obtain the actual correlations between mutations at
different sites, within an equilibrium population at a given "tolerance," which
we define to be the temperature of the statistical ensemble.


title: Singular Value Decomposition and Principal Component Analysis

abstract:
  This chapter describes gene expression analysis by Singular Value
Decomposition (SVD), emphasizing initial characterization of the data. We
describe SVD methods for visualization of gene expression data, representation
of the data using a smaller number of variables, and detection of patterns in
noisy gene expression data. In addition, we describe the precise relation
between SVD analysis and Principal Component Analysis (PCA) when PCA is
calculated using the covariance matrix, enabling our descriptions to apply
equally well to either method. Our aim is to provide definitions,
interpretations, examples, and references that will serve as resources for
understanding and extending the application of SVD and PCA to gene expression
analysis.


title: Search for long-lived states in antiprotonic lithium

abstract:
  The spectrum of the (L_i^3 + p-bar + 2e) four-body system was calculated in
an adiabatic approach. The two-electron energies were approximated by a sum of
two single-electron effective charge two-center energies as suggested in [6].
While the structure of the spectrum does not exclude the existence of
long-lived states, their experimental observability is still to be clarified.


title: A stochastic model for heart rate fluctuations

abstract:
  Normal human heart rate shows complex fluctuations in time, which is natural,
since heart rate is controlled by a large number of different feedback control
loops. These unpredictable fluctuations have been shown to display fractal
dynamics, long-term correlations, and 1/f noise. These characterizations are
statistical and they have been widely studied and used, but much less is known
about the detailed time evolution (dynamics) of the heart rate control
mechanism. Here we show that a simple one-dimensional Langevin-type stochastic
difference equation can accurately model the heart rate fluctuations in a time
scale from minutes to hours. The model consists of a deterministic nonlinear
part and a stochastic part typical to Gaussian noise, and both parts can be
directly determined from the measured heart rate data. Studies of 27 healthy
subjects reveal that in most cases the deterministic part has a form typically
seen in bistable systems: there are two stable fixed points and one unstable
one.

categories: physics.med-ph physics.bio-ph physics.data-an q-bio


title: An accelerator mode based technique for studying quantum chaos

abstract:
  We experimentally demonstrate a method for selecting small regions of phase
space for kicked rotor quantum chaos experiments with cold atoms. Our technique
uses quantum accelerator modes to selectively accelerate atomic wavepackets
with localized spatial and momentum distributions. The potential used to create
the accelerator mode and subsequently realize the kicked rotor system is formed
by a set of off-resonant standing wave light pulses. We also propose a method
for testing whether a selected region of phase space exhibits chaotic or
regular behavior using a Ramsey type separated field experiment.


title: Longest Life in the Best of Health

abstract:
  Throughout history, for reasons of health, well known personalities have
opted not to eat to satiety - to under-eat - with known benefits. Here, for the
benefits of under-eating a very simple explanation is offered and discussed in
some detail. Our distant ancestors, whose bodies we inherited, ate and weighed
a good deal less than we do. They had to run around every day to scour the
countryside for their scarce food, which kept them lean, hungry and healthy.
We, not so healthy relative over-weights, load up our shopping carts once a
week at the corner supermarket and simply eat too much for our ~50000-year-old
body design. Under-eating or not to eat one's fill appears to bring us somewhat
more in line with this design. Thereby, it causes our way of life to more
closely resemble the healthier one of our ancient forbears and enables us to
potentially live longer, to 100 and more. The putative underlying physiological
mechanisms for the health benefits of under-eating are of great interest and
therefore are touched upon here.


title: A prototype for the AMS-RICH experiment

abstract:
  The AMS spectrometer will be installed on the International Space Station in
2005. Among other improvements over the first version of the instrument, a ring
imaging Cherenkov detector (RICH) will be added and should open a new window
for cosmic-ray physics, allowing isotope separation up to A = 25 between 1 and
10 GeV/c and element identification up to Z = 25 between threshold and 1
TeV/c/nucleon. It should also contribute to the high level of redundancy
required for AMS and reject efficiency albedo particles. A second generation
prototype has been operated for a few months : the architecture and the first
results are presented.


title:
Mechanism of finite-amplitude double-component convection due to
  different boundary conditions

abstract:
  A new mechanism of double-component convection is discovered. It emerges in a
horizontal layer of Boussinesq fluid as a stable stratification due to flux
boundary conditions is added to an unstable gradient specified by fixed
boundary values. A large enough perturbation substantially decreases the stable
flux gradient but fails to mix the unstable fixed-value gradient. Steady
finite-amplitude flows reminiscent of Rayleigh--Benard convection then arise
even as the net background stratification is stable, emphasizing the importance
of the identified mechanism for double-component fluid systems.
  V2 Abstract: A new mechanism of double-component convection is discovered. It
emerges in a horizontal layer of Boussinesq fluid as a stable stratification
due to flux boundary conditions is added to an unstable gradient specified by
fixed boundary values. Driven by this mechanism, steady finite-amplitude flows
reminiscent of Rayleigh--Benard convection arise even when the background
density stratification is stable.


title: Multi-frame blind deconvolution with linear equality constraints

abstract:
  The Phase Diverse Speckle (PDS) problem is formulated mathematically as Multi
Frame Blind Deconvolution (MFBD) together with a set of Linear Equality
Constraints (LECs) on the wavefront expansion parameters. This MFBD-LEC
formulation is quite general and, in addition to PDS, it allows the same code
to handle a variety of different data collection schemes specified as data, the
LECs, rather than in the code. It also relieves us from having to derive new
expressions for the gradient of the wavefront parameter vector for each type of
data set. The idea is first presented with a simple formulation that
accommodates Phase Diversity, Phase Diverse Speckle, and Shack-Hartmann
wavefront sensing. Then various generalizations are discussed, that allows many
other types of data sets to be handled.


title: Protein induced morphological transitions in KCl crystal growth

abstract:
  We investigated the formation of KCl crystals on glass surface by phase
contrast, fluorescent, and atomic force microscopy on the micrometer scale, and
observed interesting morphological transitions as a function of the
experimental conditions. The presence of proteins in the solution from which
the salt crystals grow during the drying up leads to complex microscopic
patterns of crystals some of which are analogous to those commonly observed on
the macroscopic scale. We tested the effect of tubulin, FITC-labeled albumin
and IgG on the morphology of crystals grown either slowly or fast. A rich
variety of protein specific and concentration dependent morphologies was found
and described by a morphological diagram. We give a phenomenological
interpretation, which can explain the growth of complex patterns. Fluorescent
images prove that a protein layer covers the surface of the KCl structures. We
propose that this layer reduces the anisotropy of the effective surface tension
during growth. The tip splitting fractal regime is attributed to the decrease
of anisotropy. Other possible mechanisms, which can cause morphological
transition, are also discussed. We found elongated saw-toothed crystals induced
by proteins, especially IgG and identified their structure.


title: Limitations in predicting student performance on standardized tests

abstract:
  The Maryland Physics Expectations Survey (MPEX) describes student attitudes
and expectations toward learning, and might be used to predict normalized gains
on tests such as the Force and Motion Concept Evaluation (FMCE). These
predictions are incomplete, though, due to limitations of the standardized
tests themselves. I illustrate the problems involved in using the MPEX to
predict productive attitudes toward learning physics by focusing on two
students, both with seemingly appropriate expectations toward learning. While
one had high normalized gains, the other did not, due to "false favorable"
responses on the MPEX.


title: Atomic Force Microscopy of height fluctuations of fibroblast cells

abstract:
  We investigated the nanometer scale height fluctuations of 3T3 fibroblast
cells with the atomic force microscope (AFM) under physiological conditions.
Correlation between these fluctuations and lateral cellular motility can be
observed. Fluctuations measured on leading edges appear to be predominantly
related to actin polymerization-depolymerization processes. We found fast (5
Hz) pulsatory behavior with 1--2 nm amplitude on a cell with low motility
showing emphasized structure of stress fibres. Myosin driven contractions of
stress fibres are thought to induce this pulsation.


title:
A quantitative model for presynaptic free calcium dynamics during
  different stimulation protocols

abstract:
  The presynaptic free calcium dynamics of neurons due to various stimulation
protocols is investigated in a mathematical model. The model includes calcium
influx through voltage-dependent calcium channels, calcium buffering by
endogenous and exogenous buffers as well as calcium efflux through ATP-driven
plasma membrane calcium pumps and sodium/calcium exchangers. We want to support
a specific way of modeling which starts on the level of single proteins. Each
protein is represented by characteristics that are determined by single protein
experiments and that are considered to be widely independent of neuron types.
This allows the applications of the model to different classes of neurons and
experiments. The procedure is demonstrated for single boutons of pyramidal
neurons of the rat neocortex. The corresponding fluorescence measurements of
Koester & Sakmann (2000, J. Physiol., 529, 625) are quantitatively reproduced.
The model enables us to reconstruct the free calcium dynamics in neurons as it
would have been without fluorescence indicators starting from the fluorescence
data. We discuss the different calcium responses and find that during
high-frequency stimulation an accumulation of free calcium occurs above some
threshold stimulation frequency. The threshold frequency depends on the amount
of fluorescence indicator used in the experiment.


title:
The type of seeder cells determines the efficiency of germinal center
  reactions

abstract:
  We discuss the origin of two classes of germinal centers that have been
observed during humoral immune responses: Some germinal centers develop very
well and give rise to a large number of high affinity antibody producing plasma
cells. Other germinal center reaction are very weak and the output production
is practically absent. We propose an explanation for this nearly all-or-none
behavior of germinal center reactions: The affinity of the seeder B-cells to
the antigen is the critical parameter that determines the fate of the germinal
center reaction. This hypothesis is verified in the framework of a space-time
simulation of germinal center reactions.


title:
Controlling the cold collision shift in high precision atomic
  interferometry

abstract:
  We present here a new method based on a transfer of population by adiabatic
passage that allows to prepare cold atomic samples with a well defined ratio of
atomic density and atom number. This method is used to perform a measurement of
the cold collision frequency shift in a laser cooled cesium clock at the
percent level, which makes the evaluation of the cesium fountains accuracy at
the $10^{-16}$ level realistic. With an improved set-up, the adiabatic passage
would allow measurements of atom number-dependent phase shifts at the $10^{-3}$
level in high precision experiments.


title: On X-Ray Channeling in mu- and n-capillaries

abstract:
  In this work X-ray propagation in micro- and nano-size capillaries has been
considered in the frame of a simple unified wave theory. It is shown that the
diminishing of the channel sizes completely changes the mode of beam
transportation, namely, we obtain the transformation of surface channeling in
microcapillaries to bulk channeling in nanocapillaries (nanotubes).


title: Comment on "Gain-assisted Superluminal Light Propagation"

abstract:
  Wang, Kuzmich and Dogariu, in their 20 July, 2000, Nature article, describe
an experiment ostensibly measuring superluminal speeds of 310c via a few
percent shift in time of an optical pulse undergoing anomalous dispersion in a
pumped medium. This paper seems to have become part of the superluminal lore
and is often referenced as a profound example of superluminality. We have
closely examined the article and find serious flaws that need to be addressed.


title: Absolute Motion and Quantum Gravity

abstract:
  A new information-theoretic modelling of reality has given rise to a
quantum-foam description of space, relative to which absolute motion is
meaningful. In a previous paper (Cahill and Kitto) it was shown that in this
new physics Michelson interferometers show absolute motion effects when
operated in dielectric mode, as indeed such experiments had indicated, and
analysis of the experimental data showed that the measured speeds were all
consistent with the Cosmic Microwave Background (CMB) dipole-fit speed of
369km/s. Here the new physics is applied to the Michelson-Morley 1887
interferometer rotation curve data to demonstrate that the interferometer data
is in excellent agreement with the CMB direction (RA, Dec)=(11.20h,-7.22deg) as
well. This data also reveals a velocity component caused by the in-flow of the
quantum foam past the Earth towards the Sun at 40+/-15km/s, while analysis of
the Miller interferometer data of 1933 gives 49km/s, compared to the
theoretical value of 42km/s. This observed in-flow is a signature of quantum
gravity effects in the new physics


title: Vortex Ring Reconnections

abstract:
  We investigate numerically the Navier-Stokes dynamics of reconnecting vortex
rings at small $Re$ number. We find that reconnections are dissipative due to
the smoothing of vorticity gradients at reconnection kinks and to the formation
of secondary structures of stretched anti-parallel vorticity which transfer
kinetic energy to small scales where it is subsequently dissipated efficiently.
In addition, the relaxation of the reconnection kinks excites Kelvin waves
which due to strong damping are of low wavenumber and affect directly only
large scale properties of the flow.


title: The basis of discontinuous motion

abstract:
  We show that the instant motion of particle should be essentially
discontinuous and random. This gives the logical basis of discontinuous motion.
Since what quantum mechanics describes is the discontinuous motion of
particles, this may also answer the question 'why the quantum?'.


title:
Experimental Consequences of Time Variations of the Fundamental
  Constants

abstract:
  We discuss the experimental consequences of hypothetical time variations of
the fundamental constants. We emphasize that from a purely phenomenological
point of view, only dimensionless fundamental constants have significance. Two
classes of experiments are identified that give results that are essentially
independent of the values of all constants. Finally, we show that experiments
that are generally interpreted in terms of time variations of the dimensioned
gravitional constant $G$ are better interpreted as giving limits on the
variation of the dimensionless constant $\alpha_G=Gm_p^2/\hbar c$.

categories: physics.class-ph astro-ph hep-ph physics.gen-ph


title: Methods for parallel simulations of surface reactions

abstract:
  We study the opportunities for parallelism for the simulation of surface
reactions. We introduce the concept of a partition and we give new simulation
methods based on Cellular Automaton using partitions. We elaborate on the
advantages and disadvantages of the derived algorithms comparing with Dynamic
Monte Carlo algorithms. We find that we can get very fast simulations using
this approach trading accuracy for performance and we give experimental data
for the simulation of Ziff model.


title:
A continuous isotropic-nematic liquid crystalline transition of F-actin
  solutions

abstract:
  The phase transition from the isotropic (I) to nematic (N) liquid crystalline
suspension of F-actin of average length $3~\mu$m or above was studied by local
measurements of optical birefringence and protein concentration. Both
parameters were detected to be continuous in the transition region, suggesting
that the I-N transition is higher than 1st order. This finding is consistent
with a recent theory by Lammert, Rokhsar & Toner (PRL, 1993, 70:1650),
predicting that the I-N transition may become continuous due to suppression of
disclinations. Indeed, few line defects occur in the aligned phase of F-actin.
Individual filaments in solutions of a few mg/ml F-actin undergo fast
translational diffusion along the filament axis, whereas both lateral and
rotational diffusions are suppressed.


title: Precise fine-structure and hyperfine-structure measurements in Rb

abstract:
  We demonstrate a new technique for measuring the absolute frequencies of
atomic transitions. The technique uses a ring-cavity resonator whose length is
calibrated using a reference laser locked to the D_2 line in {87}Rb. The
frequency of this line is known to be 384 230 484.468(10) MHz. Using a second
laser locked to the D_1 line of Rb, we measure the frequencies of various
hyperfine transitions in the D_1 and D_2 lines with a precision of 30 kHz. We
obtain the following values: 120.687(17) MHz and 406.520(25) MHz for the
5P_{1/2} hyperfine constant A in {85}Rb and {87}Rb; 377 107 385.623(50) MHz and
377 107 463.209(50) MHz for the D_1 line in {85}Rb and {87}Rb; and 384 230
406.528(50) MHz for the D_2 line in {85}Rb. This yields the fine-structure
interval and the isotope shifts. The precision obtained is a significant
improvement over previous measurements.


title:
Precise measurement of hyperfine intervals using avoided crossing of
  dressed states

abstract:
  We demonstrate a technique for precisely measuring hyperfine intervals in
alkali atoms. The atoms form a three-level $\Lambda$ system in the presence of
a strong control laser and a weak probe laser. The dressed states created by
the control laser show significant linewidth reduction. We have developed a
technique for Doppler-free spectroscopy that enables the separation between the
dressed states to be measured with high accuracy even in room-temperature
atoms. The states go through an avoided crossing as the detuning of the control
laser is changed from positive to negative. By studying the separation as a
function of detuning, the center of the level-crossing diagram is determined
with high precision, which yields the hyperfine interval. Using
room-temperature Rb vapor, we obtain a precision of 44 kHz. This is a
significant improvement over the current precision of ~ 1 MHz.


title: Laser cooling and trapping of Yb from a thermal source

abstract:
  We have successfully loaded a magneto-optic trap for Yb atoms from a thermal
source without the use of a Zeeman slower. The source is placed close to the
trapping region so that it provides a large flux of atoms that can be cooled
and captured. The atoms are cooled on the ${^1S_0} \leftrightarrow {^1P_1}$
transition at 398.8 nm. We have loaded all seven stable isotopes of Yb into the
trap. For the most abundant isotope ($^{174}$Yb), we load more than $10^7$
atoms into the trap within 1 s. For the rarest isotope ($^{168}$Yb) with a
natural abundance of only 0.13%, we still load about $4 \times 10^5$ atoms into
the trap. We find that the trap population is maximized near a detuning of
$-1.5\Gamma$ and field gradient of 75 G/cm.


title: Progress of the Volume FEL (VFEL) experiments in millimeter range

abstract:
  Use of non one-dimensional distributed feedback in VFEL gives possibility of
frequency tuning in wide range. In present work dependence of lasing process on
the angle between resonant diffraction grating grooves and direction of
electron beam velocity is discussed.


title:
Evaluation of an Impulse Gravity Generator Based Beamed Propulsion
  Concept

abstract:
  This paper analyzes the suitability of a beamed propulsion concept having
properties consistent with the impulse gravity generator described by
Podkletnov et al. [physics/0108005]. The use of this propulsion concept for
orbital maneuver, Earth-to-orbit, interplanetary, and interstellar applications
based on presently available experimental results and theory is considered, and
areas for future research needed to better characterize this phenomenon are
discussed. A beam of radiation or particles with the properties described for
the impulse gravity generator would appear to be an excellent candidate for use
in beamed spacecraft propulsion. Besides the usual benefits of beamed
propulsion, it would not need sails or other special spacecraft components to
function, could safely provide high accelerations to delicate components, and
might operate at higher efficiencies than other beamed propulsion concepts.


title: Variational description of multi-fluid hydrodynamics: Uncharged fluids

abstract:
  We present a formalism for Newtonian multi-fluid hydrodynamics derived from
an unconstrained variational principle. This approach provides a natural way of
obtaining the general equations of motion for a wide range of hydrodynamic
systems containing an arbitrary number of interacting fluids and superfluids.
In addition to spatial variations we use ``time shifts'' in the variational
principle, which allows us to describe dissipative processes with entropy
creation, such as chemical reactions, friction or the effects of external
non-conservative forces. The resulting framework incorporates the
generalization of the entrainment effect originally discussed in the case of
the mixture of two superfluids by Andreev and Bashkin. In addition to the
conservation of energy and momentum, we derive the generalized conservation
laws of vorticity and helicity, and the special case of Ertel's theorem for the
single perfect fluid.
  We explicitly discuss the application of this framework to thermally
conducting fluids, superfluids, and superfluid neutron star matter. The
equations governing thermally conducting fluids are found to be more general
than the standard description, as the effect of entrainment usually seems to be
overlooked in this context. In the case of superfluid He4 we recover the
Landau--Khalatnikov equations of the two-fluid model via a translation to the
``orthodox'' framework of superfluidity, which is based on a rather awkward
choice of variables. Our two-fluid model for superfluid neutron star matter
allows for dissipation via mutual friction and also ``transfusion'' via
beta-reactions between the neutron fluid and the proton-electron fluid.


title: Scaling limit of virtual states of triatomic systems

abstract:
  For a system with three identical atoms, the dependence of the $s-$wave
virtual state energy on the weakly bound dimer and trimer binding energies is
calculated in a form of a universal scaling function. The scaling function is
obtained from a renormalizable three-body model with a pairwise Dirac-delta
interaction. It was also discussed the threshold condition for the appearance
of the trimer virtual state.


title: The Jet Calibration in the H1 Liquid Argon Calorimeter

abstract:
  The jet calibration of the Liquid-Argon-Calorimeter of the H1 Detector at
HERA is described. In the measurement of high jet transverse energies
systematic uncertainties as low as 2% can be reached in deep inelastic
scattering with a high photon virtuality (Q^2) and in photoproduction.
Furthermore, the concept of a new energy weighting scheme of H1 is presented.
First applications with a high Q^2 neutral current deep inelastic scattering
sample show that the resolution of the balance in transverse momentum between
the hadronic system and the electron is improved.


title: Exact Second-Order Structure-Function Relationships

abstract:
  Equations that follow from the Navier-Stokes equation and incompressibility
but with no other approximations are "exact.". Exact equations relating second-
and third-order structure functions are studied, as is an exact
incompressibility condition on the second-order velocity structure function.
Opportunities for investigations using these equations are discussed. Precisely
defined averaging operations are required to obtain exact averaged equations.
Ensemble, temporal, and spatial averages are all considered because they
produce different statistical equations and because they apply to theoretical
purposes, experiment, and numerical simulation of turbulence. Particularly
simple exact equations are obtained for the following cases: i) the trace of
the structure functions, ii) DNS that has periodic boundary conditions, and
iii) an average over a sphere in r-space. The last case (iii) introduces the
average over orientations of r into the structure function equations. The
energy dissipation rate appears in the exact trace equation without averaging,
whereas in previous formulations energy dissipation rate appears after
averaging and use of local isotropy. The trace mitigates the effect of
anisotropy in the equations, thereby revealing that the trace of the
third-order structure function is expected to be superior for quantifying
asymptotic scaling laws. The orientation average has the same property.


title:
Use of Dynamical Undulator Mechanism to Produce Short Wavelength
  Radiation in Volume FEL (VFEL)

abstract:
  VFEL lasing in system with dynamical undulator is described. In this system
radiation of long wavelength creates the undulator for lasing on shorter
wavelength. Two diffraction gratings with different spatial periods form VFEL
resonator. The grating with longer period pumps the resonator with long
wavelength radiation to provide necessary amplitude of undulator field. The
grating with shorter period makes mode selection for short wavelength
radiation. Lasing of such a system in terahertz frequency range is discussed.


title: Length Scales of Acceleration for Locally Isotropic Turbulence

abstract:
  Length scales are determined that govern the behavior at small separations of
the correlations of fluid-particle acceleration, viscous force, and pressure
gradient. The length scales and an associated universal constant are quantified
on the basis of published data. The length scale governing pressure spectra at
high wave numbers is discussed. Fluid-particle acceleration correlation is
governed by two length scales; one arises from the pressure gradient, the other
from the viscous force.


title:
Application of Volume diffraction grating for TeraHertz lasing in Volume
  FEL (VFEL)

abstract:
  The generation of induced radiation in volume resonator formed by metal
threads is considered. It is shown that using of such volume diffraction
grating allows increasing of lasing efficiency in terahertz range. The
requirements on beam and grating parameters are obtained.


title: Observation of Mammalian Similarity Through Allometric Scaling Laws

abstract:
  We discuss the problem of observation of natural similarity in skeletal
evolution of terrestrial mammals. Analysis is given by means of testing of the
power scaling laws established in long bone allometry, which describe
development of bones (of length $L$ and diameter $D$) with body mass in terms
of the growth exponents, \QTR{it}{e.g.} $\lambda =d\log L/d\log D$. The
bone-size evolution scenario given three decades ago by McMahon was quiet
explicit on the geometrical-shape and mechanical-force constraints that
predicted $\lambda =2/3$. This remains too far from the mammalian allometric
exponent $\lambda ^{(\exp)}=0.80\pm 0.2$, recently revised by Christiansen,
that is a chief puzzle in long bone allometry. We give therefore new insights
into McMahon's constraints and report on the first observation of the
critical-elastic-force, bending-deformation, muscle-induced mechanism that
underlies the allometric law with estimated $\lambda =0.80\pm 0.3$. This
mechanism governs the bone-size evolution with avoiding skeletal fracture
caused by muscle-induced peak stresses and is expected to be unique for small
and large mammals.


title:
Geometric Random Inner Products: A New Family of Tests for Random Number
  Generators

abstract:
  We present a new computational scheme, GRIP (Geometric Random Inner
Products), for testing the quality of random number generators. The GRIP
formalism utilizes geometric probability techniques to calculate the average
scalar products of random vectors generated in geometric objects, such as
circles and spheres. We show that these average scalar products define a family
of geometric constants which can be used to evaluate the quality of random
number generators. We explicitly apply the GRIP tests to several random number
generators frequently used in Monte Carlo simulations, and demonstrate a new
statistical property for good random number generators.


title:
Femtosecond Resolution Experiments at Third-Generation Light Sources: a
  Concept Based on the Statistical Properties of Synchrotron Radiation

abstract:
  The paper describes a new concept of visible pump/X-ray probe/slow detector
experiments that could be performed at third-generation synchrotron light
sources. We propose a technique that would allow time resolution up to
femtosecond capabilities to be recovered from a long (100 ps) X-ray probe
pulse. The visible pump pulse must be as short as the desired time resolution.
The principle of operation of the proposed pump-probe scheme is essentially
based on the statistical properties of the synchrotron radiation. These
properties are well known in statistical optics as properties of completely
chaotic polarized light. Our technique utilizes the fact that, for any
synchrotron light beam there exist some characteristic time (coherence time),
which determines the time-scale of the random fluctuations. The typical
coherence time of soft X-ray synchrotron light at the exit of monochromator is
in the femtosecond range. An excited state is prepared with a pump pulse and
then projected with a probe pulse onto a final ion state. The first statistical
quantity of interest is the variance of the number of photoelectrons detected
during synchrotron radiation pulse. The statistics of concern are defined over
an ensemble of synchrotron radiation pulses. From a set of variances measured
as a function of coherence time (inversely proportional to monochromator
bandwidth) it is possible to reconstruct the femtosecond dynamical process.


title: Supercooled Water: Contradiction to Thermodynamics

abstract:
  It has been shown that the dependence of thermal expansion coefficient and of
the isobaric heat capacity of supercooled water on the temperature contradicts
to an important thermodynamic relation.
  Keywords: Supercooled water, Negative thermal expansion, The 1st law of
thermodynamics, Anomalous behaviour of heat capacity.


title:
Accuracy and efficiency of modern methods for electronic structure
  calculation on heavy- and superheavy-element compounds

abstract:
  The methods which are actively used for electronic structure calculations of
low-lying states of heavy- and superheavy-element compounds are briefly
described. The advantages and disadvantages of calculations with the
Dirac-Coulomb-Breit Hamiltonian, Huzinaga-type pseudopotential,
shape-consistent Relativistic Effective Core Potential (RECP) and Generalized
RECP are discussed. The nonvariational technique of the electronic structure
restoration in atomic cores after the RECP calculation of a molecule is
presented. The features of some approaches accounting for electron correlation,
the configuration interaction and coupled cluster methods, are also described.
The results of calculations on E113, E114, U and other heavy-atom systems are
presented.


title: Superluminal optical pulse propagation in nonlinear coherent media

abstract:
  The propagation of light-pulse with negative group-velocity in a nonlinear
medium is studied theoretically. We show that the necessary conditions for
these effects to be observable are realized in a three-level $\Lambda$-system
interacting with a linearly polarized laser beam in the presence of a static
magnetic field. In low power regime, when all other nonlinear processes are
negligible, the light-induced Zeeman coherence cancels the resonant absorption
of the medium almost completely, but preserves the dispersion anomalous and
very high. As a result, a superluminal light pulse propagation can be observed
in the sense that the peak of the transmitted pulse exits the medium before the
peak of the incident pulse enters. There is no violation of causality and
energy conservation. Moreover, the superluminal effects are prominently
manifested in the reshaping of pulse, which is caused by the
intensity-dependent pulse velocity. Unlike the shock wave formation in a
nonlinear medium with normal dispersion, here, the self-steepening of the pulse
trailing edge takes place due to the fact that the more intense parts of the
pulse travel slower. The predicted effect can be easily observed in the well
known schemes employed for studying of nonlinear magneto-optical rotation. The
upper bound of sample length is found from the criterion that the pulse
self-steepening and group-advance time are observable without pulse distortion
caused by the group-velocity dispersion.


title:
Evolution of Electrical Resistivity, Thermal Conductivity, and
  Temperature of a solid under the action of Intense Ultrashort Laser pulse

abstract:
  The dynamical properties of Cu in a regime relevant to femtosecond micro
machining are obtained on picosecond time scales using pump-probe reflectivity
study for 100fs, 1015 W cm-2 laser pulses. The electrical resistivity is
obtained by solving Helmoltz equations. The dissipation mechanisms and scaling
laws are obtained in high and low temperature limits. The 'resistivity
saturation' effect in an unexplored regime intermediate to hot plasma and cold
solid is studied in detail. The temperature evolution and thermal conductivity
is obtained in the temporal range 0 to 30ps after the interaction of laser
pulse with solid Cu.


title: Compensated Current Injection circuit, theory and applications

abstract:
  This paper presents a detailed description, analysis and example of practical
application of a wide frequency band voltage-to-current converter. The
converter is characterized by a combination of positive and negative feedback
loops. This feature allows compensation for parasitic impedance connected in
parallel with the useful load, which in turn keeps an excitation current
flowing through the useful load independent of its impedance. The simplicity of
the circuit and its good electrical properties are additional advantages of the
scheme.


title:
Exact solutions to the Dirac equation for a Coulomb potential in $D+1$
  dimensions

abstract:
  The Dirac equation is generalized to $D+1$ space-time.The conserved angular
momentum operators and their quantum numbers are discussed. The eigenfunctions
of the total angular momenta are calculated for both odd $D$ and even $D$
cases. The radial equations for a spherically symmetric system are derived. The
exact solutions for the system with a Coulomb potential are obtained
analytically. The energy levels and the corresponding fine structure are also
presented.


title:
Combining multigrid and wavelet ideas to construct more efficient
  multiscale algorithms for the solution of Poisson's equation

abstract:
  It is shown how various ideas that are well established for the solution of
Poisson's equation using plane wave and multigrid methods can be combined with
wavelet concepts. The combination of wavelet concepts and multigrid techniques
turns out to be particularly fruitful. We propose a modified multigrid V cycle
scheme that is not only much simpler, but also more efficient than the standard
V cycle. Whereas in the traditional V cycle the residue is passed to the
coarser grid levels, this new scheme does not require the calculation of a
residue. Instead it works with copies of the charge density on the different
grid levels that were obtained from the underlying charge density on the finest
grid by wavelet transformations. This scheme is not limited to the pure wavelet
setting, where it is faster than the preconditioned conjugate gradient method,
but equally well applicable for finite difference discretizations.


title: A continuous source of translationally cold dipolar molecules

abstract:
  The Stark interaction of polar molecules with an inhomogeneous electric field
is exploited to select slow molecules from a room-temperature reservoir and
guide them into an ultrahigh vacuum chamber. A linear electrostatic quadrupole
with a curved section selects molecules with small transverse and longitudinal
velocities. The source is tested with formaldehyde (H2CO) and deuterated
ammonia (ND3). With H2CO a continuous flux is measured of approximately 10^9/s
and a longitudinal temperature of a few K. The data are compared with the
result of a Monte Carlo simulation.


title: Impedance of a Rectangular Beam Tube with Small Corrugations

abstract:
  We consider the impedance of a structure with rectangular, periodic
corrugations on two opposing sides of a rectangular beam tube. Using the method
of field matching, we find the modes in such a structure. We then limit
ourselves to the the case of small corrugations, but where the depth of
corrugation is not small compared to the period. For such a structure we
generate analytical approximate solutions for the wave number $k$, group
velocity $v_g$, and loss factor $\kappa$ for the lowest (the dominant) mode
which, when compared with the results of the complete numerical solution,
agreed well. We find: if $w\sim a$, where $w$ is the beam pipe width and $a$ is
the beam pipe half-height, then one mode dominates the impedance, with
$k\sim1/\sqrt{w\delta}$ ($\delta$ is the depth of corrugation),
$(1-v_g/c)\sim\delta$, and $\kappa\sim1/(aw)$, which (when replacing $w$ by
$a$) is the same scaling as was found for small corrugations in a {\it round}
beam pipe. Our results disagree in an important way with a recent paper of
Mostacci {\it et al.} [A. Mostacci {\it et al.}, Phys. Rev. ST-AB, {\bf 5},
044401 (2002)], where, for the rectangular structure, the authors obtained a
synchronous mode with the same frequency $k$, but with $\kappa\sim\delta$.
Finally, we find that if $w$ is large compared to $a$ then many nearby modes
contribute to the impedance, resulting in a wakefield that Landau damps.


title:
Equation-Free Multiscale Computation: enabling microscopic simulators to
  perform system-level tasks

abstract:
  We present and discuss a framework for computer-aided multiscale analysis,
which enables models at a "fine" (microscopic/stochastic) level of description
to perform modeling tasks at a "coarse" (macroscopic, systems) level. These
macroscopic modeling tasks, yielding information over long time and large space
scales, are accomplished through appropriately initialized calls to the
microscopic simulator for only short times and small spatial domains. Our
equation-free (EF) approach, when successful, can bypass the derivation of the
macroscopic evolution equations when these equations conceptually exist but are
not available in closed form. We discuss how the mathematics-assisted
development of a computational superstructure may enable alternative
descriptions of the problem physics (e.g. Lattice Boltzmann (LB), kinetic Monte
Carlo (KMC) or Molecular Dynamics (MD) microscopic simulators, executed over
relatively short time and space scales) to perform systems level tasks
(integration over relatively large time and space scales,"coarse" bifurcation
analysis, optimization, and control) directly. In effect, the procedure
constitutes a systems identification based, "closure on demand" computational
toolkit, bridging microscopic/stochastic simulation with traditional continuum
scientific computation and numerical analysis. We illustrate these ideas
through examples from chemical kinetics (LB, KMC), rheology (Brownian
Dynamics), homogenization and the computation of "coarsely self-similar"
solutions, and discuss various features, limitations and potential extensions
of the approach.


title: Antihydrogen-Hydrogen annihilation at sub-kelvin temperatures

abstract:
  Annihilation cross-section of ultra low-energy atomic antihydrogen ($%
E\le10^{-5}$ a.u.) on atomic hydrogen are calculated within a quantum
mechanical coupled channels approach. The results differ from the
extrapolations of semiclassical models to low energies. The main features of
the observables are found to be determined by a family of $H\bar{H}$
nearthreshold states.


title: A modal model for diffraction gratings

abstract:
  A description of an algorithm for a rather general modal grating calculation
is presented. Arbitrary profiles, depth, and permittivity are allowed. Gratings
built up from sub-gratings are allowed, as are coatings on the sidewalls of
lines, and arbitrary complex structure. Conical angles and good conductors are
supported.


title: Global Optimization on an Evolving Energy Landscape

abstract:
  Locating the global minimum of a complex potential energy surface is
facilitated by considering a homotopy, namely a family of surfaces that
interpolate continuously from an arbitrary initial potential to the system
under consideration. Different strategies can be used to follow the evolving
minima. It is possible to enhance the probability of locating the global
minimum through a heuristic choice of interpolation schemes and parameters, and
the continuously evolving potential landscape reduces the probability of
trapping in local minima. In application to a model problem, finding the
ground--state configuration and energy of rare--gas (Lennard--Jones) atomic
clusters, we demonstrate the utility and efficacy of this method.


title: Vortex line representation for flows of ideal and viscous fluids

abstract:
  It is shown that the Euler hydrodynamics for vortical flows of an ideal fluid
coincides with the equations of motion of a charged {\it compressible} fluid
moving due to a self-consistent electromagnetic field. Transition to the
Lagrangian description in a new hydrodynamics is equivalent for the original
Euler equations to the mixed Lagrangian-Eulerian description - the vortex line
representation (VLR). Due to compressibility of a "new" fluid the collapse of
vortex lines can happen as the result of breaking (or overturning) of vortex
lines. It is found that the Navier-Stokes equation in the vortex line
representation can be reduced to the equation of the diffusive type for the
Cauchy invariant with the diffusion tensor given by the metric of the VLR.


title:
Dynamical transitions in the evolution of learning algorithms by
  selection

abstract:
  We study the evolution of artificial learning systems by means of selection.
Genetic programming is used to generate a sequence of populations of algorithms
which can be used by neural networks for supervised learning of a rule that
generates examples. In opposition to concentrating on final results, which
would be the natural aim while designing good learning algorithms, we study the
evolution process and pay particular attention to the temporal order of
appearance of functional structures responsible for the improvements in the
learning process, as measured by the generalization capabilities of the
resulting algorithms. The effect of such appearances can be described as
dynamical phase transitions. The concepts of phenotypic and genotypic
entropies, which serve to describe the distribution of fitness in the
population and the distribution of symbols respectively, are used to monitor
the dynamics. In different runs the phase transitions might be present or not,
with the system finding out good solutions, or staying in poor regions of
algorithm space. Whenever phase transitions occur, the sequence of appearances
are the same. We identify combinations of variables and operators which are
useful in measuring experience or performance in rule extraction and can thus
implement useful annealing of the learning schedule.


title: Interaction between dust grains near a conducting wall

abstract:
  The effect of the conducting electrode on the interaction of dust grains in a
an ion flow is discussed. It is shown that two grains levitating above the
electrode at the same height may attract one another. This results in the
instability of a dust layer in a plasma sheath.


title: New investigations of the porous dielectric detectors

abstract:
  The results of the study of the multiwire porous dielectric detector and
microstrip porous dielectric detector filled with porous CsI are presented.
Detectors were exposed to $\alpha $-particles with energy of 5.46 MeV and
X-rays with energy of 5.9 keV and operated with a constant applied voltage. It
is found that right after thermal deposition of the porous CsI layer the
detector's performance is unstable, it has poor spatial resolution. However in
a course of time the performance becomes stable and it acquires high spatial
resolution.


title:
Investigation of high voltage discharges in low pressure gases through
  large ceramic superconducting electrodes

abstract:
  A device has been built and tested, in which a ceramic superconducting
cathode and a copper anode cause electrical discharges in low pressure gases,
at temperatures between 50 and 70 K. The electrodes are connected to a
capacitors array charged up to 2000 kV; peak currents are of the order of 10^4
A. The cathode has the diameter of 10 cm and is fabricated by OCMTG technology.
In discharges at voltage above 500 kV two new phenomena were observed, probably
related to each other. First, the discharge does not look like a spark, but is
a flat, glowing discharge, which originates from the whole surface of the
superconducting electrode. Furthermore, a radiation pulse is emitted at the
discharge, which propagates orthogonally to the cathode, towards the anode and
beyond it, in a collimated beam, apparently without any attenuation. The
radiation pulse carries an energy of 10^-3 J at least. The features and the
nature of this radiation have been investigated by several means, still it was
not possible to identify it; we can only exclude that it is electromagnetic
radiation or any other radiation with energy-momentum relationship E=cp.


title: Dipolar relaxation of cold sodium atoms in a magnetic field

abstract:
  A quantum mechanical close coupling theory of spin relaxation in the
stretched hyperfine level of sodium is presented. We calculate the dipolar
relaxation rate of magnetically trapped cold sodium atoms in the magnetic
field. The influence of shape resonances and the anisotropy of the dipolar
interaction on the collision dynamics are explored. We examine the sensitivity
of the calculated cross sections on the choice of asymptotic atomic state
basis.


title:
Compressibility effects on the scalar mixing in reacting homogeneous
  turbulence

abstract:
  The compressibility and heat of reaction influence on the scalar mixing in
decaying isotropic turbulence and homogeneous shear flow are examined via data
generated by direct numerical simulations (DNS). The reaction is modeled as
one-step, exothermic, irreversible and Arrhenius type. For the shear flow
simulations, the scalar dissipation rate, as well as the time scale ratio of
mechanical to scalar dissipation, are affected by compressibility and reaction.
This effect is explained by considering the transport equation for the
normalized mixture fraction gradient variance and the relative orientation
between the mixture fraction gradient and the eigenvectors of the solenoidal
strain rate tensor.


title: Solving the boundary value problem for finite Kirchhoff rods

abstract:
  The Kirchhoff model describes the statics and dynamics of thin rods within
the approximations of the linear elasticity theory. In this paper we develop a
method, based on a shooting technique, to find equilibrium configurations of
finite rods subjected to boundary conditions and given load parameters. The
method consists in making a series of small changes on a {\it trial} solution
satisfying the Kirchhoff equations but not necessarily the boundary conditions.
By linearizing the differential equations around the trial solution we are able
to push its end point to the desired position, step by step. The method is also
useful to obtain configurations of rods with fixed end points but different
mechanical parameters, such as tension, components of the moment or
inhomogeneities.


title:
Optimization of molecular clusters configurations using a Genetic
  Algorithm

abstract:
  We present a genetic algorithm developed (GA) to optimize molecular AF_6
cluster configurations with respect to their energy. The method is based on the
Darvin's evolutionary theory: structures with lowest energies survive in a
system of fixed number of clusters. Two existing structures from a given
population are combined in a special way to produce a new structure (child)
which is kept if its energy is lower than the highest energy in the ensemble.
To keep the population constant we reject the structure with the highest
energy. This algorithm gives a better result than the optimization techniques
used previously. Using the GA we have found a new structure corresponding to
the (seemingly) global minimum. The most important result is that the new
structure is detected only if the molecular cluster contains more than a
critical number of molecules.


title: Gravitational Radiation from Oscillating Gravitational Dipole

abstract:
  The concept of Gravitational Dipole is introduced starting from the recent
discovery of negative gravitational mass (gr-qc/0005107 and physics/0205089). A
simple experiment, a gravitational wave transmitter, to test this new concept
of gravitational radiation source is presented.


title: Making Micro- and Nano-beams by Channeling in Micro- and Nano-structures

abstract:
  A particle beam of very small cross-section is useful in many accelerator
applications including biological and medical ones. We show the capability of
the channeling technique using a micron-sized structure on a surface of a
single crystal, or using a nanotube, to produce beam of a cross-section down to
1 square micrometer (or nanometer). The channeled beam can be deflected and
thus well separated in angle and space from the primary and scattered
particles. Monte Carlo simulation is done to evaluate the characteristics of a
channeled microbeam. Emittances down to 0.1-0.001 nanometer radian, and flux up
to 1 million particles per square micron per second, can be achieved for
protons and ions.


title:
Computational studies of light acceptance and propagation in straight
  and curved optical fibres

abstract:
  A Monte Carlo simulation has been performed to track light rays in
cylindrical fibres by ray optics. The trapping efficiencies for skew and
meridional rays in active fibres and distributions of characteristic quantities
for all trapped light rays have been calculated. The simulation provides new
results for curved fibres, where the analytical expressions are too complex to
be solved. The light losses due to sharp bending of fibres are presented as a
function of the ratio of curvature to fibre radius and bending angle. It is
shown that a radius of curvature to fibre radius ratio of greater than 65
results in a loss of less than 10% with the loss occuring in the initial stage
of the bend (at bending angles Phi circa pi/8 rad).


title:
Microwave measurements of the photonic bandgap in a two-dimensional
  photonic crystal slab

abstract:
  We have measured the photonic bandgap in the transmission of microwaves
through a two-dimensional photonic crystal slab. The structure was constructed
by cementing acrylic rods in a hexagonal closed-packed array to form
rectangular stacks. We find a bandgap centered at approximately 11 GHz, whose
depth, width and center frequency vary with the number of layers in the slab,
angle of incidence and microwave polarization.


title: Resonant laser excitation of molecular wires

abstract:
  We investigate the influence of external laser excitations on the average
current through bridged molecules. For the computation of the current, we use a
numerically very efficient formalism that is based on the Floquet solutions of
the time-dependent molecule Hamiltonian. It is found that the current as a
function of the laser frequency exhibits characteristic peaks originating from
resonant excitations of electrons to bridge levels which are unoccupied in the
absence of the radiation. The electrical current through the molecule can
exhibit a drastic enhancement by several orders of magnitude.


title:
A Multi-Moded RF Delay Line Distribution System for the Next Linear
  Collider

abstract:
  The Delay Line Distribution System (DLDS) is an alternative to conventional
pulse compression, which enhances the peak power of rf sources while matching
the long pulse of those sources to the shorter filling time of accelerator
structures. We present an implementation of this scheme that combines pairs of
parallel delay lines of the system into single lines. The power of several
sources is combined into a single waveguide delay line using a multi-mode
launcher. The output mode of the launcher is determined by the phase coding of
the input signals. The combined power is extracted from the delay line using
mode-selective extractors, each of which extracts a single mode. Hence, the
phase coding of the sources controls the output port of the combined power. The
power is then fed to the local accelerator structures. We present a detailed
design of such a system, including several implementation methods for the
launchers, extractors, and ancillary high power rf components. The system is
designed so that it can handle the 600 MW peak power required by the NLC design
while maintaining high efficiency.


title: Penta-hepta defect chaos in a model for rotating hexagonal convection

abstract:
  In a model for rotating non-Boussinesq convection with mean flow we identify
a regime of spatio-temporal chaos that is based on a hexagonal planform and is
sustained by the {\it induced nucleation} of dislocations by penta-hepta
defects. The probability distribution function for the number of defects
deviates substantially from the usually observed Poisson-type distribution. It
implies strong correlations between the defects inthe form of density-dependent
creation and annihilation rates of defects. We extract these rates from the
distribution function and also directly from the defect dynamics.


title: Aristotle: The first encyclopedist

abstract:
  Aristotle was the first to declare himself in the class of natural
philosophers ({\em physiologoi}) and he was the first physicist because he
spelled out the first definitions of some basic physical concepts. Moreover, he
was the first encyclopedist of the world and perhaps the greatest


title: Synthetic Quantum Systems

abstract:
  So far proposed quantum computers use fragile and environmentally sensitive
natural quantum systems. Here we explore the new notion that synthetic quantum
systems suitable for quantum computation may be fabricated from smart
nanostructures using topological excitations of a stochastic neural-type
network that can mimic natural quantum systems. These developments are a
technological application of process physics which is an information theory of
reality in which space and quantum phenomena are emergent, and so indicates the
deep origins of quantum phenomena. Analogous complex stochastic dynamical
systems have recently been proposed within neurobiology to deal with the
emergent complexity of biosystems, particularly the biodynamics of higher brain
function. The reasons for analogous discoveries in fundamental physics and
neurobiology are discussed.


title:
Signal detection by means of phase coherence induced through phase
  resetting

abstract:
  Detection and location of moving prey utilizing electrosense or mechanosense
is a strategy commonly followed by animals which cannot rely on visual sense or
hearing. In this article we consider the possibility to detect the source of a
localized stimulus that travels along a chain of detectors at constant speed.
The detectors are autonomous oscillators whose frequencies have a given natural
spread. The detection mechanism is based on phase coherence which is built up
by phase resetting induced by the passing stimulus.


title: An information-theoretic formulation of Newton's second law

abstract:
  From the principle of maximum entropy for a closed system in thermal
equilibrium, for the first instance a clear relation is shown to exist between
total entropy S (in terms of arrangements of particles) and the classical
expression for the force acting on a particle in a rotating frame. We determine
relationships between arrangement of particles and force in the case of the
gravitational and elastic forces.


title:
SLAC's Polarized Electron Source Laser System and Minimization of
  Electron Beam Helicity Correlations for the E-158 Parity Violation Experiment

abstract:
  SLAC E-158 is an experiment designed to make the first measurement of parity
violation in Moller scattering. E-158 will measure the right-left cross-section
asymmetry, A_LR^Moller, in the elastic scattering of a 45-GeV polarized
electron beam off unpolarized electrons in a liquid hydrogen target. E-158
plans to measure the expected Standard Model asymmetry of ~10^-7 to an accuracy
of better than 10^-8. To make this measurement, the polarized electron source
requires for operation an intense circularly polarized laser beam and the
ability to quickly switch between right- and left-helicity polarization states
with minimal right-left helicity-correlated asymmetries in the resulting beam
parameters (intensity, position, angle, spot size, and energy), ^beam A_LR's.
This laser beam is produced by a unique SLAC-designed flashlamp-pumped
Ti:Sapphire laser and is propagated through a carefully designed set of
polarization optics. We analyze the transport of nearly circularly polarized
light through the optical system and identify several mechanisms that generate
^beam A_LR's. We show that the dominant effects depend linearly on particular
polarization phase shifts in the optical system. We present the laser system
design and a discussion of the suppression and control of ^beam A_LR's. We also
present results on beam performance from engineering and physics runs for
E-158.

categories: physics.acc-ph hep-ex nucl-ex physics.ins-det


title: A Resonant Cavity for Single-Shot Emittance Measurement

abstract:
  We present a non-invasive, resonant cavity based approach to beam emittance
measurement of a shot-to-shot non-circular beam pulse of multi-bunches. In a
resonant cavity, desired field components can be enhanced up to Q_L_lambda/pi,
where Q_L_lambda is the loaded Q of the resonance mode lambda, when the cavity
resonant mode matches with the beam operating frequency. In particular, a
Quad-cavity, with its quadrupole mode at beam operating frequency, extracts the
beam quad-moment exclusively, utilizing the symmetry of the cavity and some
simple networks to suppress common modes. Six successive beam quadrupole moment
measurements, performed at different betatron phases in a linear transport
system, allow us to determine the beam emittance, i.e., the beam size and shape
in the beam's phase space. One measurement alone provides the rms-beam size if
the beam position is given, for instance, by nearby beam-position-monitors.
This paper describes the basic design and analysis of a Quad-cavity beam
monitoring system.


title:
A Review of Salam Phase Transition in Protein Amino Acids: Implication
  for Biomolecular Homochirality

abstract:
  The origin of chirality, closely related to the evolution of life on the
earth, has long been debated. In 1991, Abdus Salam suggested a novel approach
to achieve biomolecular homochirality by a phase transition. In his subsequent
publication, he predicted that this phase transition could eventually change
D-amino acids to L-amino acids as C -H bond would break and H atom became a
superconductive atom. Since many experiments denied the configuration change in
amino acids, Salam hypothesis aroused suspicion. This paper is aimed to provide
direct experimental evidence of a phase transition in alanine, valine single
crystals but deny the configuration change of D- to L- enantiomers. New views
on Salam phase transition are presented to revalidate its great importance in
the origin of homochirality.


title:
A correlation between Earth's inclinations and the times of the cold
  events recorded in Devils Hole climate data

abstract:
  The calculated values of Earth's inclinations during the cold events in the
500 kyr climate record of Devils Hole show a correlation: they cluster in the
regions around 1 and 2 degrees. The Devils Hole record has been chosen, since
it was dated by absolute methods. Other climate records covering the same
period also have a reduced number of cold events between the two regions. The
correlation lends support to the proposal of R. A. Muller and G.J. MacDonald
that the observed 100 kyr climate cycle is due to the varying inclination of
Earth's orbit and to material located near the invariant plane which shields
off the solar radiation.


title:
`Flat Phase' Loading of a Bose-Einstein Condensate into an Optical
  Lattice

abstract:
  It has been proposed that the adiabatic loading of a Bose-Einstein Condensate
(BEC) into an optical lattice via the Mott-insulator transition can be used to
initialize a quantum computer [D. Jaksch, {\it et al.}, Phys. Rev. Lett. {\bf
81}, 3108 (1998)]. The loading of a BEC into the lattice without causing band
excitation is readily achievable; however, unless one switches on an optical
lattice very slowly, the optical lattice causes a phase to accumulate across
the condensate. We show analytically and numerically that a cancellation of
this effect is possible by adjusting the harmonic trap force-constant of the
magnetic trap appropriately, thereby facilitating quick loading of an optical
lattice for quantum computing purposes. A simple analytical theory is developed
for a non-stationary BEC in a harmonic trap.


title: Perspectives for Positron Emission Tomography with RPCs

abstract:
  In this study we address the feasibility and main properties of a positron
emission tomograph (PET) based on RPCs. The concept, making use of the
converter-plate principle, takes advantage of the intrinsic layered structure
of RPCs and its simple and economic construction. The extremely good time and
position resolutions of RPCs also allow the TOF-PET imaging technique to be
considered. Monte-Carlo simulations, supported by experimental data, are
presented and the main advantages and drawbacks for applications of potential
interest are discussed.


title: Optimal series representations for numerical path integral simulations

abstract:
  By means of the Ito-Nisio theorem, we introduce and discuss a general
approach to series representations of path integrals. We then argue that the
optimal basis for both ``primitive'' and partial averaged approaches is the
Wiener sine-Fourier basis. The present analysis also suggests a new approach to
improving the convergence of primitive path integral methods. Current work
indicates that this new technique, the ``reweighted'' method, converges as the
cube of the number of path variables for ``smooth'' potentials. The technique
is based on a special way of approximating the Brownian bridge which enters the
Feynman-Kac formula and it does not require the Gaussian transform of the
potential for its implementation.


title:
Impedance Measurement Setup for Higher-Order Mode Studies in NLC
  Accelerator Structures with the Wire Method

abstract:
  Dipole modes are the main cause of transverse emittance dilution in the
Japanese Linear Collider / Next Linear Collider (JLC/NLC). A diagnostic setup
has been built in order to investigate them. The method is based on using a
coaxial wire to excite and measure electromagnetic modes of accelerating
structures. This method can offer a more efficient and less expensive procedure
than the ASSET facility. Initial measurements have been made and are presented
in this paper.


title:
Amplified Spontaneous Emission enhanced Forward Stimulated Raman
  Scattering in dye solutions

abstract:
  We study forward stimulated Raman emission from weakly fluorescent dye
4'-diethylamino-N-methyl-4-stilbazolium tosylate (DEST) in 1,2,dichloroethane
solution excited by a 28 ps, 532 nm Nd: YAG laser. Neat 1, 2, dichloroethane
emits the first Stokes line at 631 nm with a spectral width of 1.6 nm
corresponding to a Raman shift of 2956 per cm. We observe reduction of spectral
width with the addition of DEST in 1, 2, dichloroethane solution. The single
pass conversion efficiency for forward Raman emission is as high as 20 percent
in a 1 cm path length sample. The pulse duration of forward stimulated Raman
emission measured by a third order autocorrelation technique is 10 ps in neat
1, 2, dichloroethane, whereas it is nearly 3 ps for 0.04 mM of DEST solution.


title:
An evolution equation of the population genetics: relation to the
  density-matrix theory of quasiparticles with general dispersion laws

abstract:
  The Waxman-Peck theory of the population genetics is discussed in regard of
soil bacteria. Each bacterium is understood as a carrier of a phenotypic
parameter p. The central aim is the calculation of the probability density with
respect to p of the carriers living at time t>0. The theory involves two small
parameters: the mutation probability $\mu$ and a parameter $\gamma$ involved in
a function w(p) defining the fitness of the bacteria to survive the generation
time $\tau$ and give birth to offspring. The mutation from a state p to a state
q is defined by a Gaussian. The author focuses attention on an equation
generalizing Waxman's equation. The author solves this equation in the standard
style of a perturbation theory and discusses how the solution depends on the
choice of the fitness function w(p). In a sense, the function
$c(p)=1-w(p)/w(0)$ is analogous to the dispersion function E(p) of fictitious
quasiparticles. With a general function c(p), the distribution function
${\mathit\Phi}(p,t;0)$ is composed of a delta-function component,
$N(t)\delta(p)$, and a blurred component. The author shows that asymptotically
N(t) may tend to a positive value, in contrast with zero resulting from
Waxman's approximation where $c(p)\sim p^2$.


title: Radiative charge transfer lifetime of the excited state of (NaCa)$^+$

abstract:
  New experiments were proposed recently to investigate the regime of cold
atomic and molecular ion-atom collision processes in a special hybrid
neutral-atom--ion trap under high vacuum conditions. The collisional cooling of
laser pre-cooled Ca$^+$ ions by ultracold Na atoms is being studied. Modeling
this process requires knowledge of the radiative lifetime of the excited
singlet A$^1\Sigma^+$ state of the (NaCa)$^+$ molecular system. We calculate
the rate coefficient for radiative charge transfer using a semiclassical
approach. The dipole radial matrix elements between the ground and the excited
states, and the potential curves were calculated using Complete Active Space
Self-Consistent field and M\"oller-Plesset second order perturbation theory
(CASSCF/MP2) with an extended Gaussian basis, 6-311+G(3df). The semiclassical
charge transfer rate coefficient was averaged over a thermal Maxwellian
distribution. In addition we also present elastic collision cross sections and
the spin-exchange cross section. The rate coefficient for charge transfer was
found to be $2.3\times 10^{-16}$ cm$^3$/sec, while those for the elastic and
spin-exchange cross sections were found to be several orders of magnitude
higher ($1.1\times 10^{-8}$ cm$^3$/sec and $2.3\times 10^{-9}$ cm$^3$/sec,
respectively). This confirms our assumption that the milli-Kelvin regime of
collisional cooling of calcium ions by sodium atoms is favorable with the
respect to low loss of calcium ions due to the charge transfer.


title:
Equation of State of Chemical System: From True Equilibrium to True
  Chaos

abstract:
  The article presents results of preliminary study of solutions to recently
offered basic thermodynamic equation for equilibrium in chemical systems with
focus on chaotic behavior. Classical part of that equation was investigated
earlier in a series of papers. In this work a similarity between
one-dimensional logistic map and non-classical (chaotic) term of the equation
was discussed to introduce the problem. Results of this work allow us to
evaluate the region where open equilibrium belongs to the basin of regular
attractor and leads to trivial solutions with zero deviation from true
thermodynamic equilibrium, and then to find first bifurcation threshold as a
limit of open equilibrium and a limit of the classical region as well. Features
of the basic equation are discussed with regard to relative values of the
chaotic and thermodynamic temperatures. Obtained results prompt us to consider
the basic equation of new theory to be the general equation of state of
chemical systems.


title: Electron Beam Production by Pyroelectric Crystals

abstract:
  Pyroelectric crystals are used to produce self-focused electron beams with
energies greater than 170 keV. No high voltage power supply or electron gun is
needed. The system works by simply changing the temperature of a crystal of
LiNbO3 or LiTaO3 by about 100oC in dilute gas. Electron beam energy spectra as
well as positive-ion-beam energy spectra and profiles are shown. A change in
the crystal temperature of 100oC will cause a spontaneous change in
polarization. The change in polarization will be manifested by a change in
charge on the surface of the crystal. It is this uncompensated charge that
produces the electric field, which accelerates the electrons, or the positive
ions and gives rise to the plasma, which in turn focuses them. The source of
the accelerated electrons or positive ions is gas molecules ionized near the
crystal surface. When the crystal surface is negative electrons are accelerated
away from it and positive ions are attracted to the surface. These positive
ions reduce the net negative charge on the surface thereby reducing the
electric field, which causes the electron energy to decrease over time even
though the focal properties remain unchanged. When the surface is positive the
reverse obtains and the positive ion beam energy decreases over time as well.
We will present video clips, photographic and electronic data that demonstrate
many of the characteristics and applications of these electron beams.


title: Isochores Merit the Prefix 'Iso'

abstract:
  The isochore concept in human genome sequence was challenged in an analysis
by the International Human Genome Sequencing Consortium (IHGSC). We argue here
that a statement in IGHSC analysis concerning the existence of isochore is
incorrect, because it had applied an inappropriate statistical test. To test
the existence of isochores should be equivalent to a test of homogeneity of
windowed GC%. The statistical test applied in the IHGSC's analysis, the
binomial test, is however a test of a sequence being random on the base level.
For testing the existence of isochore, or homogeneity in GC%, we propose to use
another statistical test: the analysis of variance (ANOVA). It can be shown
that DNA sequences that are rejected by binomial test may not be rejected by
the ANOVA test.


title: Ab Initio Modeling of Ecosystems with Artificial Life

abstract:
  Artificial Life provides the opportunity to study the emergence and evolution
of simple ecosystems in real time. We give an overview of the advantages and
limitations of such an approach, as well as its relation to individual-based
modeling techniques. The Digital Life system Avida is introduced and prospects
for experiments with ab initio evolution (evolution "from scratch"),
maintenance, as well as stability of ecosystems are discussed.


title:
Foldy-Wouthuysen transformation and a quasiparaxial approximation scheme
  for the scalar wave theory of light beams

abstract:
  The Foldy-Wouthuysen iterative diagonalization technique is applied to the
Helmholtz equation to obtain a Hamiltonian description of the propagation of a
monochromatic quasiparaxial light beam through a system in which the refractive
index $n(x,y,z)$ varies about a background value $n_0$ such that
$|n(x,y,z)-n_0| \ll n_0$. This technique is presented as an alternative to the
conventional method of series expansion of the radical. Besides reproducing all
the traditional quasiparaxial terms, this method leads to additional terms in
the optical Hamiltonian.

categories: physics.optics physics.acc-ph physics.gen-ph quant-ph


title: Role of Molecular Dissociation in Feshbach-Interacting 85Rb Condensates

abstract:
  Recent Feshbach-resonance experiments with 85Rb Bose-Einstein condensates
have led to a host of unexplained results: dramatic losses of condensate atoms
for an across-resonance sweep of the magnetic field, a collapsing condensate
with a burst of atoms emanating from the remnant condensate, increased losses
for decreasing interaction times--until very short times are reached, and
coherent oscillations between remnant and burst atoms. In particular, the
amplitude of the remnant-burst oscillations, and the corresponding missing
atoms, have prompted speculation as to the formation of a molecular condensate.
Using a minimal mean-field model, we find that rogue dissociation, molecular
dissociation to noncondensate atom pairs, is qualitatively implicated as the
physical mechanism responsible for these observations, although very little
molecular condensate is formed. Refining the model provides excellent
quantitative agreement with the experimental remnant-burst oscillations, and
the fraction of molecular condensate accounts almost entirely for the measured
atom loss.

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


title: Atom lithography using MRI-type feature placement

abstract:
  We demonstrate the use of frequency-encoded light masks in neutral atom
lithography. We demonstrate that multiple features can be patterned across a
monotonic potential gradient. Features as narrow as 0.9 microns are fabricated
on silicon substrates with a metastable argon beam. Internal state manipulation
with such a mask enables continuously adjustable feature positions and feature
densities not limited by the optical wavelength, unlike previous light masks.


title:
The calculation of a normal force between multiparticle contacts using
  fractional operators

abstract:
  This paper deals with the complex problem of how to simulate multiparticle
contacts. The collision process is responsible for the transfer and dissipation
of energy in granular media. A novel model of the interaction force between
particles has been proposed and tested. Such model allows us to simulate
multiparticle collisions and granular cohesion dynamics.

categories: physics.comp-ph cs.CE cs.NA math.NA physics.class-ph physics.geo-ph


title: Two-photon E1M1 decay of 2 3P0 states in heavy heliumlike ions

abstract:
  Two-photon E1M1 transition rates are evaluated for heliumlike ions with
nuclear charges in the range Z = 50-94. The two-photon rates modify previously
published lifetimes/transition rates of 2 3P0 states. For isotopes with nuclear
spin I not equal 0, where hyperfine quenching dominates the 2 3P0 decay,
two-photon contributions are significant; for example, in heliumlike 187 Os the
two-photon correction is 3% of the total rate. For isotopes with I= 0, where
the 2 3P0 decay is unquenched, the E1M1 corrections are even more important
reaching 60% for Z=94. Therefore, to aid in the interpretation of experiments
on hyperfine quenching in heliumlike ions and to provide a more complete
database for unquenched transitions, a knowledge of E1M1 rates is important.


title: To "stabilize'' or not to "stabilize"?

abstract:
  The controversial question of whether or not an atom will be completely
ionized by a laser pulse of arbitrarily increasing intensity is discussed.


title: Gauge Invariant Evaluation of Nuclear Polarization with Collective Model

abstract:
  The nuclear-polarization (NP) energies with the collective model commonly
employed in the NP calculations for hydrogenlike heavy ions are found to have
serious gauge violations when the ladder and cross diagrams only are taken into
account. Using the equivalence of charge-current density with a schematic
microscopic model, the NP energy shifts with the collective model are gauge
invariantly evaluated for the $1s_{1/2}$ states in $^{208}_{~82}$Pb$^{81+}$ and
$^{238}_{~92}$U$^{91+}$.