title: Symmetry Scheme for Amino Acid Codons

abstract:
  Group theoretical concepts are invoked in a specific model to explain how
only twenty amino acids occur in nature out of a possible sixty four. The
methods we use enable us to justify the occurrence of the recently discovered
twenty first amino acid selenocysteine, and also enables us to predict the
possible existence of two more, as yet undiscovered amino acids.


title:
Precision study of 6p 2Pj - 8s 2S1/2 relative transition matrix elements
  in atomic Cs

abstract:
  A combined experimental and theoretical study of transition matrix elements
of the 6p 2Pj - 8s 2S1/2 transition in atomic Cs is reported. Measurements of
the polarization-dependent two-photon excitation spectrum associated with the
transition were made in an approximately 200 cm-1 range on the low frequency
side of the 6s 2S1/2 - 6p 2P3/2 resonance. The measurements depend
parametrically on the relative transition matrix elements, but also are
sensitive to far-off-resonance 6s 2S1/2 - np 2Pj - 8s 2S1/2 transitions. In the
past, this dependence has yielded a generalized sum rule, the value of which is
dependent on sums of relative two-photon transition matrix elements. In the
present case, best available determinations from other experiments are combined
with theoretical matrix elements to extract the ratio of transition matrix
elements for the 6p 2Pj - 8s 2S1/2 (j = 1/2,3/2) transition. The resulting
experimental value of 1.423(2) is in excellent agreement with the theoretical
value, calculated using a relativistic all-order method, of 1.425(2).


title: Polar Concentration of Elements in Tree Leaves

abstract:
  A long-term study of the elements Mg, Al, Si, P, Ca, S, Cl, Fe and Mn in
leaves is in progress. The objective of this study is to develop a week-by-week
profile of these elements in leaves during several growing seasons. The profile
includes the following information: (1) Which elements each tree collects in
its leaves. (2) The location in the leaf with the highest concentration, top
side, under side or interior. (3) The week during the growing season when each
element first appears in the leaves of each tree. (4) The change in the
relative concentration from week to week. (5) The source of the element i.e.,
deposition from the atmosphere or the root system of the tree. This information
is profile for each year and will be correlated with environmental conditions
for that year. Leaves are collected weekly from first unfolding in early spring
until leaf drop in the fall. They are from the 31 trees and 26 species in
Broome County, NY. From time to time leaves from most of the 26 species are
being randomly collected from trees growing throughout the northeastern US.


title:
Deterministic Chaos Model for Self-Organized Adaptive Networks in
  Atmospheric Flows

abstract:
  The complex spatiotemporal patterns of atmospheric flows resulting from the
cooperative existence of fluctuations ranging in size from millimeters to
thousands of kilometers are found to exhibit long-range spatial and temporal
correlations manifested as the selfsimilar fractal geometry to the global cloud
cover pattern and the inverse power law form for the atmospheric eddy energy
spectrum. Such long-range spatial and temporal correlations are ubiquitous to
extended natural dynamical systems and is a signature of the strange attractor
design characterizing deterministic chaos or self-organized criticality. The
unified network of global atmospheric circulations is analogous to the neural
networks of the human brain.


title: Coupled surface polaritons and the Casimir force

abstract:
  The Casimir force between metallic plates made of realistic materials is
evaluated for distances in the nanometer range. A spectrum over real
frequencies is introduced and shows narrow peaks due to surface resonances
(plasmon polaritons or phonon polaritons) that are coupled across the vacuum
gap. We demonstrate that the Casimir force originates from the attraction
(repulsion) due to the corresponding symmetric (antisymmetric) eigenmodes,
respectively. This picture is used to derive a simple analytical estimate of
the Casimir force at short distances. We recover the result known for Drude
metals without absorption and compute the correction for weakly absorbing
materials.


title: Precision Drift Chambers for the Atlas Muon Spectrometer

abstract:
  ATLAS is a detector under construction to explore the physics at the Large
Hadron Collider at CERN. It has a muon spectrometer with an excellent momentum
resolution of 3-10%, provided by three layers of precision monitored-drift-tube
chambers in a toroidal magnetic field. A single drift tube measures a track
point with a mean resolution close to 100 micron, even at the expected high
neutron and gamma background rates. The tubes are positioned within the chamber
with an accuracy of 20 microns, achieved by elaborate construction and assembly
monitoring procedures.


title: Performance of a micro-TPC for a time-resolved neutron PSD

abstract:
  We report on the performance of a micro-TPC with a micro pixel
chamber($\mu$-PIC) readout for a time-resolved neutron position-sensitive
detector(PSD). Three-dimensional tracks and the Bragg curves of protons with
energies of around 1 MeV were clearly detected by the micro-TPC. More than 95%
of gamma-rays of 511 keV were found to be discriminated by simple analysis.
Simulation studies showed that the total track length of proton and triton
emitted from the $\rm {}^{3}He$(n,p(573 keV))$\rm {}^{3}H(191 keV)$ reaction is
about 1.2 cm, and that both particles have large energy losses ($\rm > 200
keV/cm$) in 1 atm Ar+$\rm C_{2}H_{6}(10%)$+${}^{3}$He($< 1%$). These values
suit the current performance of the micro-TPC, and we conclude that a
time-resolved neutron PSD with spatial resolution of sub-millimeters shall be
developed as an application of the micro-TPC.


title:
The game of the "very small" and the "very big": The case of the Doppler
  Effect

abstract:
  In the study of the Doppler Effect, non-locality is not taken into account.
We present two cases in which a continuous change in the receiver's speed and
in the angle at which the successive wavecrests are received takes place. In
each case the error committed by not taking into account the non-locality is
evaluated.


title: Weak Turbulent Kolmogorov Spectrum for Surface Gravity Waves

abstract:
  We study the long-time evolution of gravity waves on deep water exited by the
stochastic external force concentrated in moderately small wave numbers. We
numerically implement the primitive Euler equations for the potential flow of
an ideal fluid with free surface written in canonical variables, using
expansion of the Hamiltonian in powers of nonlinearity of up to fourth order
terms.
  We show that due to nonlinear interaction processes a stationary energy
spectrum close to $|k| \sim k^{-7/2}$ is formed. The observed spectrum can be
interpreted as a weak-turbulent Kolmogorov spectrum for a direct cascade of
energy.

categories: physics.flu-dyn nlin.PS physics.ao-ph physics.comp-ph


title: Decay of the monochromatic capillary wave

abstract:
  It was demonstrated by direct numerical simulation that, in the case of
weakly nonlinear capillary waves, one can get resonant waves interaction on the
discrete grid when resonant conditions are never fulfilled exactly. The waves's
decay pattern was obtained. The influence of the mismatch of resonant condition
was studied as well.


title: Weak turbulence of gravity waves

abstract:
  For the first time weak turbulent theory was demonstrated for the surface
gravity waves. Direct numerical simulation of the dynamical equations shows
Kolmogorov turbulent spectra as predicted by analytical analysis from kinetic
equation.


title:
Spectral element modeling of three dimensional wave propagation in a
  self-gravitating Earth with an arbitrarily stratified outer core

abstract:
  This paper deals with the spectral element modeling of seismic wave
propagation at the global scale. Two aspects relevant to low-frequency studies
are particularly emphasized. First, the method is generalized beyond the
Cowling approximation in order to fully account for the effects of
self-gravitation. In particular, the perturbation of the gravity field outside
the Earth is handled by a projection of the spectral element solution onto the
basis of spherical harmonics. Second, we propose a new formulation inside the
fluid which allows to account for an arbitrary density stratification. It is
based upon a decomposition of the displacement into two scalar potentials, and
results in a fully explicit fluid-solid coupling strategy. The implementation
of the method is carefully detailed and its accuracy is demonstrated through a
series of benchmark tests.


title: Optical measurement of microscopic torques

abstract:
  In recent years there has been an explosive development of interest in the
measurement of forces at the microscopic level, such as within living cells, as
well as the properties of fluids and suspensions on this scale, using optically
trapped particles as probes. The next step would be to measure torques and
associated rotational motion. This would allow measurement on very small scales
since no translational motion is needed. It could also provide an absolute
measurement of the forces holding a stationary non-rotating particle in place.
The laser-induced torque acting on an optically trapped microscopic
birefringent particle can be used for these measurements. Here we present a new
method for simple, robust, accurate, simultaneous measurement of the rotation
speed of a laser trapped birefringent particle, and the optical torque acting
on it, by measuring the change in angular momentum of the light from passing
through the particle. This method does not depend on the size or shape of the
particle or the laser beam geometry, nor does it depend on the properties of
the surrounding medium. This could allow accurate measurement of viscosity on a
microscopic scale.


title:
Towards a sensitive search for variation of the fine structure constant
  using radio-frequency E1 transitions in atomic dysprosium

abstract:
  It has been proposed that the radio-frequency electric-dipole (E1) transition
between two nearly degenerate opposite-parity states in atomic dysprosium
should be highly sensitive to possible temporal variation of the fine structure
constant ($\alpha$) [V. A. Dzuba, V. V. Flambaum, and J. K. Webb, Phys. Rev. A
{\bf 59}, 230 (1999)]. We analyze here an experimental realization of the
proposed search in progress in our laboratory, which involves monitoring the E1
transition frequency over a period of time using direct frequency counting
techniques. We estimate that a statistical sensitivity of $|\adota| \sim
10^{-18}$/yr may be achieved and discuss possible systematic effects that may
limit such a measurement.


title:
Orientation of biological cells using plane-polarized Gaussian beam
  optical tweezers

abstract:
  Optical tweezers are widely used for the manipulation of cells and their
internal structures. However, the degree of manipulation possible is limited by
poor control over the orientation of trapped cells. We show that it is possible
to controllably align or rotate disc shaped cells - chloroplasts of Spinacia
oleracea - in a plane polarised Gaussian beam trap, using optical torques
resulting predominantly from circular polarisation induced in the transmitted
beam by the non-spherical shape of the cells.


title: Numerical Modelling of Optical Trapping

abstract:
  Optical trapping is a widely used technique, with many important applications
in biology and metrology. Complete modelling of trapping requires calculation
of optical forces, primarily a scattering problem, and non-optical forces. The
T-matrix method is used to calculate forces acting on spheroidal and
cylindrical particles.


title: Contents of Physics Related E-Print Archives

abstract:
  The frontiers of physics related e-print archives (1994-2002) at
http://www.arxiv.org/archives/physics web service are explored from 7770
submissions. No. of e-prints in the six research disciplines besides physics
(5390) were: Condensed matter(754), Quantum physics(279), Astrophysics(222),
Chemical physics(129), High energy physics Phenomenology(118), and High energy
physics-Theory(100)). By keyword contents following major sub-fields have high
frequency: Atomic physics(1258), General physics(1121), Chemical physics(892),
Accelerator physics(769), Optics(686), Biological physics(674), and
Computational physics(607). Interdomainary co-word cluster analysis revealed
higher e-print contents for: Classical physics-General physics(108), Quantum
physics-Optics(53), and High energy physics (Phenomenology)Atomic physics(49).
Prominent contributors were B. G. Sidharth (India), V. V. Flambaum (Australia),
Antonina N. Fedorova (Russia), and Michael G. Zeitlin (Russia).


title:
Compact, Robust Source of Cold Atoms for Efficient Loading of a Magnetic
  Guide

abstract:
  We report a compact (<20cm3), robust source for producing a bright flux of
cold atoms, which can be loaded efficiently into a magnetic guide. A continuous
flux of up to 8 x 109 87Rb atoms/s have been produced from this 2D+ vapor cell
MOT. The flux had a divergence of 12.5 mrad and velocity could be controlled in
the range 2-15 m/s. This flux was coupled continuously into a magnetic guide
with high efficiency.


title:
Students' Models of Newton's Second Law in Mechanics and
  Electromagnetism

abstract:
  We investigated students' use of Newton's second law in mechanics and
electromagnetism contexts by interviewing students in a two-semester
calculus-based physics course. We observed that students' responses are
consistent with three mental models. These models appeard in mechanics contexts
and were transferred to electromagnetism contexts. We developed an inventory to
help instructors identify these models and direct students towards the correct
one.


title:
Calculation and optical measurement of laser trapping forces on
  non-spherical particles

abstract:
  Optical trapping, where microscopic particles are trapped and manipulated by
light is a powerful and widespread technique, with the single-beam gradient
trap (also known as optical tweezers) in use for a large number of biological
and other applications.
  The forces and torques acting on a trapped particle result from the transfer
of momentum and angular momentum from the trapping beam to the particle.
  Despite the apparent simplicity of a laser trap, with a single particle in a
single beam, exact calculation of the optical forces and torques acting on
particles is difficult. Calculations can be performed using approximate
methods, but are only applicable within their ranges of validity, such as for
particles much larger than, or much smaller than, the trapping wavelength, and
for spherical isotropic particles.
  This leaves unfortunate gaps, since wavelength-scale particles are of great
practical interest because they are readily and strongly trapped and are used
to probe interesting microscopic and macroscopic phenomena, and non-spherical
or anisotropic particles, biological, crystalline, or other, due to their
frequent occurance in nature, and the possibility of rotating such objects or
controlling or sensing their orientation.
  The systematic application of electromagnetic scattering theory can provide a
general theory of laser trapping, and render results missing from existing
theory. We present here calculations of force and torque on a trapped particle
obtained from this theory and discuss the possible applications, including the
optical measurement of the force and torque.


title: Multipole expansion of strongly focussed laser beams

abstract:
  Multipole expansion of an incident radiation field - that is, representation
of the fields as sums of vector spherical wavefunctions - is essential for
theoretical light scattering methods such as the T-matrix method and
generalised Lorenz-Mie theory (GLMT). In general, it is theoretically
straightforward to find a vector spherical wavefunction representation of an
arbitrary radiation field. For example, a simple formula results in the useful
case of an incident plane wave. Laser beams present some difficulties. These
problems are not a result of any deficiency in the basic process of spherical
wavefunction expansion, but are due to the fact that laser beams, in their
standard representations, are not radiation fields, but only approximations of
radiation fields. This results from the standard laser beam representations
being solutions to the paraxial scalar wave equation. We present an efficient
method for determining the multipole representation of an arbitrary focussed
beam.


title:
Calculation of the T-matrix: general considerations and application of
  the point-matching method

abstract:
  The T-matrix method is widely used for the calculation of scattering by
particles of sizes on the order of the illuminating wavelength. Although the
extended boundary condition method (EBCM) is the most commonly used technique
for calculating the T-matrix, a variety of methods can be used.
  We consider some general principles of calculating T-matrices, and apply the
point-matching method to calculate the T-matrix for particles devoid of
symmetry. This method avoids the time-consuming surface integrals required by
the EBCM.


title: Optical alignment and spinning of laser-trapped microscopic particles

abstract:
  Light-induced rotation of absorbing microscopic particles by transfer of
angular momentum from light to the material raises the possibility of optically
driven micromachines. The phenomenon has been observed using elliptically
polarized laser beams or beams with helical phase structure. But it is
difficult to develop high power in such experiments because of overheating and
unwanted axial forces, limiting the achievable rotation rates to a few hertz.
This problem can in principle be overcome by using transparent particles,
transferring angular momentum by a mechanism first observed by Beth in 1936,
when he reported a tiny torque developed in a quartz waveplate due to the
change in polarization of transmitted light. Here we show that an optical
torque can be induced on microscopic birefringent particles of calcite held by
optical tweezers. Depending on the polarization of the incident beam, the
particles either become aligned with the plane of polarization (and thus can be
rotated through specified angles) or spin with constant rotation frequency.
Because these microscopic particles are transparent, they can be held in
three-dimensional optical traps at very high power without heating. We have
observed rotation rates in excess of 350 Hz.


title: Optimal embedding parameters: A modelling paradigm

abstract:
  Reconstruction of a dynamical system from a time series requires the
selection of two parameters, the embedding dimension $d_e$ and the embedding
lag $\tau$. Many competing criteria to select these parameters exist, and all
are heuristic. Within the context of modeling the evolution operator of the
underlying dynamical system, we show that one only need be concerned with the
product $d_e\tau$. We introduce an information theoretic criteria for the
optimal selection of the embedding window $d_w=d_e\tau$. For infinitely long
time series this method is equivalent to selecting the embedding lag that
minimises the nonlinear model prediction error. For short and noisy time series
we find that the results of this new algorithm are data dependent and superior
to estimation of embedding parameters with the standard techniques.


title:
On the possibility for short time when, where earthquakes prediction
  with the using geomagnetic field measurements

abstract:
  This paper is an attempt for arguing the possibility for short time when,
where and how Earthquakes prediction. The local when Earthquake prediction is
based on the connection between geomagnetic quakes and the next incoming
minimum or maximum of tidal gravitational potential. The probability time
window for the predicted earthquake is +/-1 day for the minimum and +/-2 days
for the maximum. The preliminary statistic estimation on the basis of
distribution of the time difference between predicted and occurred earthquake
for the period 2001-2002 in Balkan, Black Sea region is given. Examples for
posteriori earthquakes when predictions at different World regions, using
archive Intermagnet local data, are given. The possibility for local when,
where earthquake prediction is based on the accurate, with special space and
time scales, monitoring of the electromagnetic field under, on and over Earth
surface. The periodically upgraded information from Seismic hazard maps is
essential. The possibility for local when, where and how Earthquake prediction
is based on the monitoring of geomagnetic field, electro-potential distribution
in the Earth crust and atmosphere, spatial and time distribution of Earth
surface radiation, gravitational anomalyties map, season and day independent
temperature depth distribution, water sources parameters (debit, temperature,
chemical composition, radioactivity), gas emissions, ionosphere condition
parameters, Earth radiation belt parameters, Sun wind, Seismic hazard maps
information for crust parameters (strain, deformation, displacement) and
biological precursors.


title: Influence of radiative damping on the optical-frequency susceptibility

abstract:
  Motivated by recent discussions concerning the manner in which damping
appears in the electric polarizability, we show that (a) there is a dependence
of the nonresonant contribution on the damping and that (b) the damping enters
according to the "opposite sign prescription." We also discuss the related
question of how the damping rates in the polarizability are related to
energy-level decay rates.


title:
How to apply importance-sampling techniques to simulations of optical
  systems

abstract:
  This report contains a tutorial introduction to the method of importance
sampling. The use of this method is illustrated for simulations of the
noise-induced energy jitter of return-to-zero pulses in optical communication
systems.


title: Wave Mechanics of a Two Wire Atomic Beamsplitter

abstract:
  We consider the problem of an atomic beam propagating quantum mechanically
through an atom beam splitter. Casting the problem in an adiabatic
representation (in the spirit of the Born-Oppenheimer approximation in
molecular physics) sheds light on explicit effects due to non-adiabatic passage
of the atoms through the splitter region. We are thus able to probe the fully
three dimensional structure of the beam splitter, gathering quantitative
information about mode-mixing, splitting ratios,and reflection and transmission
probabilities.


title: Field-linked States of Ultracold Polar Molecules

abstract:
  We explore the character of a novel set of ``field-linked'' states that were
predicted in [A. V. Avdeenkov and J. L. Bohn, Phys. Rev. Lett. 90, 043006
(2003)]. These states exist at ultralow temperatures in the presence of an
electrostatic field, and their properties are strongly dependent on the field's
strength. We clarify the nature of these quasi-bound states by constructing
their wave functions and determining their approximate quantum numbers. As the
properties of field-linked states are strongly defined by anisotropic dipolar
and Stark interactions, we construct adiabatic surfaces as functions of both
the intermolecular distance and the angle that the intermolecular axis makes
with the electric field. Within an adiabatic approximation we solve the 2-D
Schrodinger equation to find bound states, whose energies correlate well with
resonance features found in fully-converged multichannel scattering
calculations.


title: CMS barrel Resistive Plate Chambers - tests and results

abstract:
  CMS experiment will use Resistive Plate Chambers (RPCs) as dedicated muon
trigger detectors. The first 24 RPCs for the barrel muon system of the CMS
experiment have been assembled and tested. A brief description of the cosmic
muon telescope used for the tests is given. The preliminary results for the
chamber performance are presented.


title: Quasireplicas and universal lengths of microbial genomes

abstract:
  Statistical analysis of distributions of occurrence frequencies of short
words in 108 microbial complete genomes reveals the existence of a set of
universal "root-sequence lengths" shared by all microbial genomes. These
lengths and their universality give powerful clues to the way microbial genomes
are grown. We show that the observed genomic properties are explained by a
model for genome growth in which primitive genomes grew mainly by maximally
stochastic duplications of short segments from an initial length of about 200
nucleotides (nt) to a length of about one million nt typical of microbial
genomes. The relevance of the result of this study to the nature of
simultaneous random growth and information acquisition by genomes, to the
so-called RNA world in which life evolved before the rise of proteins and
enzymes and to several other topics are discussed.


title:
Evolution of economic entities under heterogeneous
  political/environmental conditions within a Bak-Sneppen-like dynamics

abstract:
  A model for economic behavior, under heterogeneous spatial economic
conditions is developed. The role of selection pressure in a Bak-Sneppen-like
dynamics with entity diffusion on a lattice is studied by Monte-Carlo
simulation taking into account business rule(s), like enterprise - enterprise
short range location "interaction"(s), business plan(s) through spin-offs or
merging and enterprise survival evolution law(s). It is numerically found that
the model leads to a sort of phase transition for the fitness gap as a function
of the selection pressure.


title:
Determination of thorium, uranium, and potassium elemental
  concentrations in surface soils in Cyprus

abstract:
  A comprehensive study was conducted to determine thorium, uranium and
potassium elemental concentrations in surface soils throughout the accessible
area of Cyprus using high-resolution gamma-ray spectrometry. A total of 115
soil samples was collected from all over the bedrock surface of the island
based on the different lithological units of the study area. The soil samples
were sieved through a fine mesh, sealed in 1000-mL plastic Marinelli beakers,
and measured in the laboratory in terms of their gamma radioactivity for a
counting time of 18 hours each. From the measured gamma-ray spectra, elemental
concentrations were determined for thorium (range from 2.5x10^-3 to 9.8 micro g
g-1), uranium (from 8.1x10^-4 to 3.2 micro g g-1) and potassium (from 1.3x10^-4
to 1.9 %). The Arithmetic mean values (A.M. +- S.D.) calculated are (1.2 +-
1.7) micro g g-1, (0.6 +- 0.7) micro g g-1, and (0.4 +- 0.3) %, for thorium,
uranium and potassium, respectively, which are by a factor of three to six
lower than the world average values of 7.4 micro g g-1 (Th), 2.8 micro g g-1
(U) and 1.3 % (K) derived from all data available worldwide. The best-fitting
relation between the concentrations of Th and K versus U, and also of K versus
Th, is essentially of linear type with a correlation coefficient of 0.93, 0.84,
and 0.90, respectively. The Th/U, K/U, and K/Th ratios (slopes) calculated are
equal to 2.0, 2.8x10^3,and 1.4x10^3, respectively.


title:
A Comprehensive Study of Natural Gamma Radioactivity Levels and
  Associated Dose Rates from Surface Soils in Cyprus

abstract:
  A survey was carried out to determine activity concentration levels and
associated dose rates from the naturally occurring radionuclides Th-232, U-238,
and K-40, in the various geological formations appearing throughout the
geographically accessible area of Cyprus, by means of high-resolution gamma-ray
spectrometry. A total number of 115 representative soil samples were collected
from all over the bedrock surface of the island, based on the different
lithological units of the study area, sieved through a fine mesh, sealed in
1000-mL plastic Marinelli beakers, and measured in the laboratory with respect
to their gamma radioactivity for a counting time of 18 hours each. From the
measured spectra, activity concentrations were determined for Th-232 (range
from 1.0x10^-2 to 39.8 Bq/kg), U-238 (from 1.0x10^-2 to 39.3 Bq/kg) and K-40
(from 4.0x10^-2 to 565.8 Bq/kg). Gamma absorbed dose rates in air outdoors were
calculated to be in the range of 1.1x10^-2 - 51.3 nGy/h, depending on the
geological features, with an overall mean value of 8.7 nGy/h and a standard
deviation of 8.4 nGy/h. This value is by a factor of about 7 below the
corresponding population-weighted world-averaged value of 60 nGy/h reported by
UNSCEAR (2000), and one of the lowest that has been reported from similar
investigations worldwide. Assuming a 20% occupancy factor, the corresponding
effective dose rates outdoors equivalent to the population were calculated to
be between 1.3x10^-2 and 62.9 micro Sv/y, with an arithmetic mean value of 10.7
micro Sv/y and a standard deviation of 10.3 micro Sv/y.


title: Non-deterministic random bit generator based on electronics noise

abstract:
  Non-deterministic random bits are needed in many scientific fields.
Unfortunately today's computers are very limited in ability to produce them. We
present here a method for extraction of non-deterministic random bits from
random physics processes, and one practical realization of a physical generator
based on it. The method is shown to deliver increasingly good randomness in the
limit of slow sampling. A sample of approximately $10^9$ bits produced by the
physical generator prototype is subjected to a series of well-known statistical
tests showing no weaknesses.


title: Construction and Tests of Modules for the ATLAS Pixel Detector

abstract:
  The ATLAS Pixel Detector is the innermost layer of the ATLAS tracking system
and will contribute significantly to the ATLAS track and vertex reconstruction.
The detector consists of identical sensor-chip-hybrid modules, arranged in
three barrels in the centre and three disks on either side for the forward
region.
  The position of the pixel detector near the interaction point requires
excellent radiation hardness, mechanical and thermal robustness, good long-term
stability, all combined with a low material budget. The pre-production phase of
such pixel modules has nearly finished, yielding fully functional modules.
Results are presented of tests with these modules.


title: Effects of Bulk Viscosity in Non-linear Bubble Dynamics

abstract:
  The non-linear bubble dynamics equations in a compressible liquid have been
modified considering the effects of compressibility of both the liquid and the
gas at the bubble interface. A new bubble boundary equation has been derived,
which includes a new term resulted from the liquid bulk viscosity effects. The
influence of this term has been numerically investigated considering the
effects of water vapor and chemical reactions on the bubble evolution. The
results clearly indicate that the new term has an important damping role at the
collapse, so that its consideration decreases the amplitude of the bubble
rebounds after the collapse. This damping feature is more remarkable for higher
deriving pressures.


title:
Development of a triple GEM UV-photon detector operated in pure CF4 for
  the PHENIX experiment

abstract:
  Results obtained with a triple GEM detector operated in pure CF4 with and
without a reflective CsI photocathode are presented. The detector operates in a
stable mode at gains up to 10^4. A deviation from exponential growth starts to
develop when the total charge exceeds ~ 4 10^6 e leading to gain saturation
when the total charge is ~ 2 10^7 e and making the structure relatively robust
against discharges. No aging effects are observed in the GEM foils after a
total accumulated charge of ~ 10 mC/cm^2 at the anode. The ion back-flow
current to the reflective photocathode is comparable to the electron current to
the anode. However, no significant degradation of the CsI photocathode is
observed for a total ion back-flow charge of ~ 7 mC/cm^2.


title:
Precision frequency measurement of visible intercombination lines of
  strontium

abstract:
  We report the direct frequency measurement of the visible 5s$^2$ $^1$S$_0$-5s
5p$^3$P$_1$ intercombination line of strontium that is considered a possible
candidate for a future optical frequency standard. The frequency of a
cavity-stabilized laser is locked to the saturated fluorescence in a thermal Sr
atomic beam and is measured with an optical-frequency comb-generator referenced
to the SI second through a GPS signal. The $^{88}$Sr transition is measured to
be at 434 829 121 311 (10) kHz. We measure also the $^{88}$Sr-$^{86}$Sr isotope
shift to be 163 817.4 (0.2) kHz.


title: Statistical properties of transport in plasma turbulence

abstract:
  The statistical properties of the $E \times B$ flux in different types of
plasma turbulence simulations are investigated using probability density
distribution functions (PDF). The physics included in the models ranges from
two dimensional drift-wave turbulence to three dimensional MHD simulations. The
PDFs of the flux surface averaged transport are in good agreement with an
extreme value distribution (EVD). This is interpreted as a signature of
localized vortical structures dominating the transport on a flux surface.
Models accounting for a local input of energy and including the global
evolution of background profiles show a more bursty behavior in 2D as well as
3D simulations of interchange and drift type turbulence. Although the PDFs are
not Gaussian, again no algebraic tails are observed. The tails are, in all
cases considered, in excellent agreement with EVDs.


title:
Quantum-Foam In-Flow Theory of Gravity and the Global Positioning System
  (GPS)

abstract:
  It is shown that a new quantum-foam in-flow theory of gravity is
mathematically equivalent to the General Relativity theory of gravity for the
operation of the Global Positioning System (GPS). The differences between the
two theories become experimentally evident in other situations such as in the
so-called `dark matter' effect, in the observation of absolute motion and ipso
facto in the observation of the in-flow motion into the Sun, and in the
observation of a new class of gravitational waves, effects which are present in
existing experimental observations, but are not within General Relativity. This
new theory of gravity arises within the information-theoretic Process Physics.


title: Nonlinear absorption and refraction in near-detuned rubidium vapor

abstract:
  Using the z-scan technique, we have measured the self-induced absorptive and
refractive nonlinear behavior of hot atomic rubidium vapor within the Doppler
profile of the D2 line. We observe large nonlinear amplitude and phase effects
with only tens of microwatts of incident power. Our results are in good
agreement with numerical calculations based on an analytic model of a Doppler-
broadened two-level system.


title:
Finite nuclear size effect on Lamb shift of s1/2, p1/2, and p3/2 atomic
  states

abstract:
  We consider one-loop self-energy and vacuum polarization radiative
corrections to the shift of atomic energy level due to finite nuclear size.
Analytic expressions for vacuum polarization corrections are derived. For the
self-energy of p1/2 and p3/2 states in addition to already known terms we
derive next-to-leading nonlogarithmic Z\alpha-terms. Together with
contributions obtained earlier the terms derived in the present work give
explicit analytic expressions for s1/2 and p1/2 corrections which agree with
results of previous numerical calculations up to Z=100 (Z is the nuclear charge
number). We also show that the finite nuclear size radiative correction for a
p3/2 state is not small compared to the similar correction for a p1/2 state at
least for small Z.


title:
Geometric interpretation of the 3-dimensional coherence matrix for
  nonparaxial polarization

abstract:
  The 3-dimensional coherence matrix is interpreted by emphasising its
invariance with respect to spatial rotations. Under these transformations, it
naturally decomposes into a real symmetric positive definite matrix,
interpreted as the moment of inertia of the ensemble (and the corresponding
ellipsoid), and a real axial vector, corresponding to the mean angular momentum
of the ensemble. This vector and tensor are related by several inequalities,
and the interpretation is compared to those in which unitary invariants of the
coherence matrix are studied.


title:
Numerical Simulations of Intermittent Transport in Scrape-Off Layer
  Plasmas

abstract:
  Two-dimensional fluid simulations of interchange turbulence for geometry and
parameters relevant for the scrape-off layer of confined plasmas are presented.
We observe bursty ejection of particles and heat from the bulk plasma in the
form of blobs. These structures propagate far into the scrape-off layer where
they are lost due to transport along open magnetic field lines. From
single-point recordings it is shown that the blobs have asymmetric conditional
wave forms and lead to positively skewed and flat probability distribution
functions. The radial propagation velocity may reach one tenth of the sound
speed. These results are in excellent agreement with recent experimental
measurements.


title: SQUID Magnetometry for Cancer Screening a Feasibility Study

abstract:
  The recent demonstration that nanoparticles associated with various
biological molecules and pharmacological agents can be administered
systemically to humans, without toxicity from the particles, has opened a new
era in the targeting of such particles to specific tissues in the body for the
imaging and therapy of disease. The majority of particles used for this purpose
contain iron and are detected in the body by magnetic resonance imaging. We
believe a superconducting quantum interference device (SQUID) could provide
quantitative and spatial information relevant to localization of
superparamagnetic nanoparticles directed to a specific cell target in vivo. We
envision a scanning system consisting of a DC induction field, a transport
device, and an array of planar first order gradiometer coils coupled to DC
SQUID amplifiers. We performed a set of computer simulations using
experimentally determined values for concentrations of paramagnetic particles
achievable in specific tissues of the mouse in vivo and concentrations of
particles linked to monoclonal antibodies specific to antigens of two human
cancer cell lines in vitro. An instrument to target distance of 10 centimeters
was selected so that for an average adult scanning both the anterior and
posterior surfaces could provide coverage of most of the body. The simulations
demonstrate the feasibility of SQUID magnetometry for monitoring achievable
concentrations of superparamagnetic particles in vivo and raise the possibility
of using this approach to detect and localize collections of abnormal cells
targeted by such particles.

categories: physics.med-ph physics.bio-ph physics.ins-det q-bio.TO


title:
Efficient collinear third-harmonic generation in a single
  two-dimensional nonlinear photonic crystal

abstract:
  We propose novel multi-phase-matched process that starts with generation of a
pair of symmetric second-harmonic waves. Each of them interacts again with the
fundamental wave to produce two constructively interfering third harmonic waves
collinear to the fundamental input wave.


title: Wake Fields and Impedance

abstract:
  Knowledge of the electromagnetic interaction between a beam and the
surrounding vacuum chamber is necessary in order to optimize the accelerator
performance in terms of stored current. Many instability phenomena may occur in
the machine because of the fields produced by the beam and acting back on
itself as in a feedback device. Basically, these fields produce an extra
voltage and energy gain, affecting the longitudinal dynamics, and a transverse
momentum kick which deflects the beam. In this paper we describe the main
features of this interaction with typical machine components.


title:
Optical Manipulation of Long-range Interactions at the 3s+3p Asymptote
  of Na$_2$

abstract:
  We investigate the influence of a laser field, which is near-resonant to the
atomic sodium 3$^2$P$_{1/2}$ $\to$ 3$^2$D$_{3/2}$ transition, on the last bound
levels of the A$^1\Sigma^+_u$ state in Na$_2$. In a molecular beam experiment
level shifts up to $\approx$ 100 MHz and light induced line broadenings were
observed using an optical double resonance excitation scheme. Moreover, the
coupling laser can reduce the number of bound levels of the A state by one or
more units, which effectively means that in the picture of a collision of a
3$^2$S$_{1/2}$ and a 3$^2$P$_{1/2}$-atom the scattering phase is altered by
more than $\pi$. The observed effects are interpreted as light induced
couplings of the A$^1\Sigma^+_u$ state, which correlates to the
3s$_{1/2}$+3p$_{1/2}$ asymptote, to the $4^1\Sigma^+_g$ and $2^1\Pi_g$ states
at the 3s$_{1/2}$+3d$_{3/2}$ asymptote. We performed multi-channel
calculations, applying the mapped Fourier grid method, which reproduce our
experimentally observed level shifts well.


title: The mass of the tau neutrinos

abstract:
  We have shown previously that the mass of the muon neutrino can be determined
from the energy released in the decay of the pi (+-) mesons, and that the mass
of the electron neutrino can be determined from the energy released in the
decay of the neutron. We will now show how the mass of the tau neutrino can be
determined from the decay of the D(s)(+-) mesons.


title: Dynamics of Immobilized Flagella

abstract:
  Although the auger-like 'swimming' motility of the African trypanosome was
described upon its discovery over one hundred years ago, the precise
biomechanical and biophysical properties of trypanosome flagellar motion has
not been elucidated. In this study, we describe five different modes of
flagellar beat/wave patterns in African trypanosomes by microscopically
examining the flagellar movements of chemically tethered cells. The dynamic
nature of the different beat/wave patterns suggests that flagellar motion in
Trypanosoma brucei is a complex mixture of oscillating waves, rigid bends,
helical twists and non-linear waves. Interestingly, we have observed
soliton-like depression waves along the flagellar membrane, suggesting a
nonlinear mechanism for the dynamics of this system. The physical model is
inspired by the 2-dimensional elastic dynamics of a beam, and by taking into
account uniform distribution of molecular motors torque and nonlinear terms in
the curvature.

categories: physics.bio-ph nlin.AO nlin.PS physics.chem-ph physics.flu-dyn q-bio.CB q-bio.QM q-bio.SC


title: Subject Access through Community Partnerships: A Case Study

abstract:
  Innovations in scholarly communication have resulted in changing roles for
authors, publishers and libraries. Traditional roles are disappearing and
players are actively seeking or reluctantly assuming new roles. Library roles
are changing as they become involved in building and indexing electronic (e-)
repositories and support new modes of e-research. A library-run service, the
SPIRES particle physics databases, has not only weathered, but also lead, many
of the transitions that have shaped the landscape of epublishing and
e-research. This has been possible through an intense and in-depth partnership
with its user community. The strategies used and lessons learned can help other
libraries craft cost-effective roles in this new environment.


title: Comment on `Vector potential of the Coulomb gauge'

abstract:
  The expression for the Coulomb-gauge vector potential in terms of the
`instantaneous' magnetic field derived by Stewart [2003 Eur. J. Phys. 24, 519]
by employing Jefimenko's equation for the magnetic field and Jackson's formula
for the Coulomb-gauge vector potential can be proven much more simply.


title: On vector potential of the Coulomb gauge

abstract:
  The question of an instantaneous action (A M Stewart 2003 Eur. J. Phys. 24,
519) can be approached in a systematic way applying the Helmhotz vector
decomposition theorem to a two-parameter Lorenz-like gauge. We thus show that
only the scalar potential may act instantaneously.


title:
Mode-Field Radius of Photonic Crystal Fibers Expressed by the
  V-parameter

abstract:
  We numerically calculate the equivalent mode-field radius of the fundamental
mode in a photonic crystal fiber (PCF) and show that this is a function of the
V-parameter only and not the relative hole size. This dependency is similar to
what is found for graded-index standard fibers and we furthermore show that the
relation for the PCF can be excellently approximated with the same general
mathematical expression. This is to our knowledge the first semi-analytical
description of the mode-field radius of a PCF.


title:
The probability of making a correct decision in hypotheses testing as
  estimator of quality of planned experiments

abstract:
  In the report the approach to estimation of quality of planned experiments is
considered. This approach is based on the analysis of uncertainty, which will
take place under the future hypotheses testing about the existence of a new
phenomenon in Nature. The probability of making a correct decision in
hypotheses testing is proposed as estimator of quality of planned experiments.
This estimator allows to take into account systematics and statistical
uncertainties in determination of signal and background rates.

categories: physics.data-an hep-ex math.PR math.ST stat.TH


title:
Studies of Proximity Focusing RICH with an aerogel radiator using
  Flat-panel multi-anode PMTs (Hamamatsu H8500)

abstract:
  A proximity focusing ring imaging Cherenkov detector using aerogel as the
radiator has been studied for an upgrade of the Belle detector at the
KEK-B-factory. We constructed a prototype Cherenkov counter using a 4 x 4 array
of 64-channel flat-panel multi-anode PMTs (Hamamatsu H8500) with a large
effective area. The aerogel samples were made with a new technique to obtain a
higher transmission length at a high refractive index (n=1.05). Multi-channel
PMTs are read-out with analog memory chips. The detector was tested at the
KEK-PS pi2 beam line in November, 2002. To evaluate systematically the
performance of the detector, tests were carried out with various aerogel
samples using pion beams with momenta between 0.5 GeV/c and 4 GeV/c. The
typical angular resolution was around 14 mrad, and the average number of
detected photoelectrons was around 6. We expect that pions and kaons can be
separated at a 4 sigma level at 4 GeV/c.


title: Spatial methods for event reconstruction in CLEAN

abstract:
  In CLEAN (Cryogenic Low Energy Astrophysics with Noble gases), a proposed
neutrino and dark matter detector, background discrimination is possible if one
can determine the location of an ionizing radiation event with high accuracy.
We simulate ionizing radiation events that produce multiple scintillation
photons within a spherical detection volume filled with liquid neon. We
estimate the radial location of a particular ionizing radiation event based on
the observed count data corresponding to that event. The count data are
collected by detectors mounted at the spherical boundary of the detection
volume. We neglect absorption, but account for Rayleigh scattering. To account
for wavelength-shifting of the scintillation light, we assume that photons are
absorbed and re-emitted at the detectors. Here, we develop spatial Maximum
Likelihood methods for event reconstruction, and study their performance in
computer simulation experiments. We also study a method based on the centroid
of the observed count data. We calibrate our estimates based on training data.


title: Efficient magneto-optical trapping of Yb atoms with a violet laser diode

abstract:
  We report the first efficient trapping of rare-earth Yb atoms with a
high-power violet laser diode (LD). An injection-locked violet LD with a 25 mW
frequency-stabilized output was used for the magneto-optical trapping (MOT) of
fermionic as well as bosonic Yb isotopes. A typical number of $4\times 10^6$
atoms for $^{174}$Yb with a trap density of $\sim 1\times10^8/$cm$^3$ was
obtained. A 10 mW violet external-cavity LD (ECLD) was used for the
one-dimensional (1D) slowing of an effusive Yb atomic beam without a Zeeman
slower resulting in a 35-fold increase in the number of trapped atoms. The
overall characteristics of our compact violet MOT, e.g., the loss time of 1 s,
the loading time of 400 ms, and the cloud temperature of 0.7 mK, are comparable
to those in previously reported violet Yb MOTs, yet with a greatly reduced cost
and complexity of the experiment.


title: Opto-mechanical probes of resonances in amplifying microresonators

abstract:
  We investigate whether the force and torque exerted by light pressure on an
irregularly shaped dielectric resonator allow to detect resonant frequencies,
delivering information complemental to the scattering cross section by
mechanical means. The peak-to-valley ratio in the torque signal can be many
times larger than in the scattering cross section, and, furthermore, depends on
the structure of the resonance wave pattern. The far-field emission pattern of
the associated quasi-bound states can be tested by the angular dependence of
the mechanical probes at finite amplification rate. We relate the force and
torque to the scattering matrix and present numerical results for an annularly
shaped dielectric resonator.


title: Towards a classification of wave catastrophes

abstract:
  Wave catastrophes are characterized by logarithmic phase singularities.
Examples are light at the horizon of a black hole, sound in transsonic fluids,
waves in accelerated frames, light in singular dielectrics and slow light close
to a zero of the group velocity. We show that the wave amplitude grows with a
half-integer power for monodirectional and symmetric wave catastrophes.


title: A QCD Generated Mass Spectrum

abstract:
  Using the interquark potential we obtain a formula for the mass spectrum of
elementary particles. The simple formula gives the masses of all known
elementary particles with an error of about three percent or less. This
includes the recently discovered Ds (2317) and 1.5GeV Pentaquark particles.


title:
Carbon Dimer in Silicon Cage: A Class of Highly Stable Silicon Carbide
  Clusters

abstract:
  A class of silicon carbide cage clusters with two carbon atoms inside the
silicon cage and with high stabilities are presented. The theoretical formalism
used is Hartree-Fock theory followed by second order many body perturbation
theory to account for correlation effects and geometry optimizations at the
second order perturbation theory level are performed without any symmetry
constraints. The smallest "cage" is found to be a silicon cube with the carbon
dimer inside the cube. Based on the simultaneous criteria of high binding
energy, high vertical ionization potential, high homo-lumo gap, and low
electron affinity, Si_14C_2 with a close fullerene like structure, is predicted
to be a particularly stable cluster both al all-electron and at pseudopotential
level of calculations. The C-C bond lengths and the HOMO-LUMO gaps of the
clusters are both found to oscillate with the cluster size.


title: Gravitational waves and ether's wind

abstract:
  A very recent research validates observationally the theoretical
demonstrations of the physical non-existence of the gravitational waves.


title:
Fine Structure Constants in n-dimensional Physical Spaces through
  Dimensional Analysis

abstract:
  We use Vaschy-Buckhingham Theorem as a systematic tool to build univocal
n-dimensional extensions of the electric and gravitational fine structure
constants and show that their ratio is dimensionally invariant. The results
allow us to obtain the relative standard uncertainty on the
three-dimensionality of space as 1.08 $10^{-13}$.


title: Complex functions as lumps of energy

abstract:
  We present an application of the basic mathematical concept of complex
functions as topological solitons, a most interesting area of research in
physics. Such application of complex theory is virtually unknown outside the
community of soliton researches.


title: Moment based methods for ensemble assessment and calibration

abstract:
  We describe various moment-based ensemble interpretation models for the
construction of probabilistic temperature forecasts from ensembles. We apply
the methods to one year of medium range ensemble forecasts and perform in and
out of sample testing. Our main conclusion is that probabilistic forecasts
derived from the ensemble mean using regression are just as good as those based
on the ensemble mean and the ensemble spread using a more complex calibration
algorithm. The explanation for this seems to be that the predictable component
of the variability of the forecast uncertainty is only a small fraction of the
total forecast uncertainty. Users of ensemble temperature forecasts are
advised, until further evidence becomes available, to ignore the ensemble
spread and build probabilistic forecasts based on the ensemble mean alone.


title:
Ultrastable Optical Clock with Neutral Atoms in an Engineered Light
  Shift Trap

abstract:
  An ultrastable optical clock based on neutral atoms trapped in an optical
lattice is proposed. Complete control over the light shift is achieved by
employing the $5s^2 {}^1S_0 \to 5s5p {}^3P_0$ transition of ${}^{87}{\rm Sr}$
atoms as a "clock transition". Calculations of ac multipole polarizabilities
and dipole hyperpolarizabilities for the clock transition indicate that the
contribution of the higher-order light shifts can be reduced to less than 1
mHz, allowing for a projected accuracy of better than $ 10^{-17}$.


title:
Spectroscopy of the $^1S_0-{}^3P_0$ Clock Transition of $^{87}$Sr in an
  Optical Lattice

abstract:
  We report on the spectroscopy of the $5s^2 {}^1S_0 (F=9/2) \to 5s5p {}^3P_0
(F=9/2)$ clock transition of ${}^{87}{\rm Sr}$ atoms (natural linewidth of 1
mHz) trapped in a one-dimensional optical lattice. Recoilless transitions with
a linewidth of 0.7 kHz as well as the vibrational structure of the lattice
potential were observed. By investigating the wavelength dependence of the
carrier linewidth, we determined the magic wavelength, where the light shift in
the clock transition vanishes, to be $813.5\pm0.9$ nm.


title: Mode Competition in Gas and Semiconductor Lasers

abstract:
  The output spectrum of both gas and semiconductor lasers usually contains
more than one frequency. Multimode operation in gas versus semiconductor lasers
arises from different physics. In gas lasers, slow equilibration of the
electron populations at different energies makes each frequency an independent
single-mode laser. The slow electron diffusion in semiconductor lasers,
combined with the spatially varying optical intensity patterns of the modes,
makes each region of space an independent single-mode laser. We develop a rate
equation model for the photon number in each mode which captures all these
effects. Plotting the photon number versus pumping rate for the competing
modes, in both subthreshold and above threshold operation, illustrates the
changes in the laser output spectrum due to either slow equilibration or slow
diffusion of electrons.


title:
A Historical Note about how the Property was Discovered that
  Hydrogenated Substances Increase the Radioactivity Induced by Neutrons

abstract:
  At the "Domus Galilaeana" in Pisa, many original documents and records are
kept, which belong to the scientific activity carried out by Enrico Fermi until
1938. I compared those documentary sources with the supported evidences, the
personal recollections, concerning the discovery that hydrogenated substances
increase the radioactivity induced by neutrons: such a comparison leads to the
conclusion that the discovery occurred on October 20th 1934, i.e., two days
before the date that all the accounts that have been supported so far report.
That suggests that any historical study to come, and regarding the experiments
carried out by Fermi and his group on neutrons, cannot neglect to analyse
carefully the accounts regarding those experiments and to compare them with the
archive records.


title: The Richardson's Law in Large-Eddy Simulations of Boundary Layer flows

abstract:
  Relative dispersion in a neutrally stratified planetary boundary layer (PBL)
is investigated by means of Large-Eddy Simulations (LES). Despite the small
extension of the inertial range of scales in the simulated PBL, our Lagrangian
statistics turns out to be compatible with the Richardson $t^3$ law for the
average of square particle separation. This emerges from the application of
nonstandard methods of analysis through which a precise measure of the
Richardson constant was also possible. Its values is estimated as $C_2\sim 0.5$
in close agreement with recent experiments and three-dimensional direct
numerical simulations.


title: Diagrammar For Random Flight Motion

abstract:
  We present a perturbation theory by extending a prescription due to Feynman
for computing the probability density function for the random flight motion.
The method can be applied to a wide variety of otherwise difficult
circumstances. The series for the exact moments, if not the distribution
itself, for many important cases can be summed for arbitrary times. As
expected, the behavior at early time regime, for the sample processes
considered, deviate significantly from diffusion theory; a fact with important
consequences in various applications such as financial physics. A half dozen
sample problems are solved starting with one posed by Feynman who originally
solved it only to first order. Another illustrative case is found to be a
physically more plausible substitute for both the Uhlenbeck-Ornstein and the
Wiener processes. The remaining cases we've solved are useful for applications
in regime-switching and isotropic scattering of light in turbid media. It is
demonstrated that under isotropic random flight with invariant-speed, the
description of motion in higher dimensions is recursively related to either the
one or two dimensional movement. Also for this motion, we show that the
solution heretofore presumed correct in one dimension, applies only to the case
we've named the "Shooting Gallery" problem; a special case of the full problem.
A new class of functions dubbed "Damped-exponential-integrals" are also
identified.


title: Spectra of pyroelectric X-ray generator

abstract:
  The construction of X-ray generator based on a pyroelectric crystal LiNbO3 is
described. Some properties of radiation spectra from the X-ray generator are
presented. Measurements of the spectra were performed at heating and cooling of
the crystal with copper and chromium targets. The maximum energy in the X-ray
spectrum versus crystal temperature is presented.


title:
Applications of (Wigner-Type) Time-Frequency Distributions to Sonar and
  Radar Signal Analysis

abstract:
  Wigner-type distributions have shown their effectiveness in classification
problems of sonar and radar. We present an overview of applications where
resonance features in echoes scattered from targets insonified or illuminated
with short pulses are studied in the joint time-frequency domain. We first show
the acoustic case of an elastic shell with a few filler materials submerged in
water and insonified by the "clicks" dolphins generate when they are
echo-locating the targets to classify them. The second example deals with a
ground-penetrating radar used to identify buried land mines. We have compared
the performance of various time-frequency distributions as well as a technique
to combine these with a "fuzzy-cluster" representation of the subsurface target
signatures.


title:
Analysis and optimisation of the tuning of the twelfths for a clarinet
  resonator

abstract:
  Even if the tuning between the first and second register of a clarinet has
been optimized by instrument makers, the lowest twelfths remain slightly too
large (inharmonicity). In this article, we study the problem from two different
points of view. First, we systematically review various physical reasons why
this inharmonicity may take place, and the effect of different bore
perturbations inserted in cylindrical instruments. Applications to a real
clarinet resonator and comparisons with impedance measurements are then
presented. A commonly accepted idea is that the register hole is the dominant
cause for this inharmonicity: it is natural to expect that opening this hole
will raise the resonance frequencies of the instrument, except for the note for
which the hole is at the pressure node. We show that the real situation is
actually more complicated because other effects, such as open holes or bore
taper and bell, introduce resonance shifts that are comparable but with
opposite sign, so that a relatively good overall compensation takes place. The
origin of the observed inharmonicity in playing frequencies is therefore
different. In a second part, we use an elementary model of the clarinet in
order to isolate the effect of the register hole: a perfect cylindrical tube
without closed holes. Optimization techniques are then used to calculate an
optimum location for the register hole; the result turns out to be close to the
location chosen by clarinet makers. Finally, attempts are made numerically to
improve the situation by introducing small perturbations in the higher part of
the cylindrical resonator, but no satisfactory improvement is obtained.


title: An Object-Oriented Approach to Partial Wave Analysis

abstract:
  Partial Wave Analysis has traditionally been carried out using a set of tools
handcrafted for each experiment. By taking an object-oriented approach, the
design presented in this paper attempts to create a more generally useful, and
easily extensible, environment for analyzing many different type of data.


title: Metastable neon collisions: anisotropy and scattering length

abstract:
  In this paper we investigate the effective scattering length $a$ of
spin-polarized Ne*. Due to its anisotropic electrostatic interaction, its
scattering length is determined by five interaction potentials instead of one,
even in the spin-polarized case, a unique property among the Bose condensed
species and candidates. Because the interaction potentials of Ne* are not known
accurately enough to predict the value of the scattering length, we investigate
the behavior of $a$ as a function of the five phase integrals corresponding to
the five interaction potentials. We find that the scattering length has five
resonances instead of only one and cannot be described by a simple gas-kinetic
approach or the DIS approximation. However, the probability for finding a
positive or large value of the scattering length is not enhanced compared to
the single potential case. The complex behavior of $a$ is studied by comparing
a quantum mechanical five-channel numerical calculation to simpler two-channel
models. We find that the induced dipole-dipole interaction is responsible for
coupling between the different |\Omega> states, resulting in an inhomogeneous
shift of the resonance positions and widths in the quantum mechanical
calculation as compared to the DIS approach. The dependence of the resonance
positions and widths on the input potentials turns out to be rather
straightforward. The existence of two bosonic isotopes of Ne* enables us to
choose the isotope with the most favorable scattering length for efficient
evaporative cooling towards the Bose-Einstein Condensation transition, greatly
enhancing the feasibility to reach this transition.


title:
Violations of fundamental symmetries in atoms and tests of unification
  theories of elementary particles

abstract:
  High-precision measurements of violations of fundamental symmetries in atoms
are a very effective means of testing the standard model of elementary
particles and searching for new physics beyond it. Such studies complement
measurements at high energies. We review the recent progress in atomic parity
nonconservation and atomic electric dipole moments (time reversal symmetry
violation), with a particular focus on the atomic theory required to interpret
the measurements.


title: A Tip of the TOE

abstract:
  Using standard methods from string theory, this paper presents a
comprehensive survey about the most important aspects of the theory of sand.
Special interest is put on the examination of the sand-wind duality and the
interaction of ordinary (non-supersymmetric) sand with the heat field of the
earth, as solution of the field inequalities of a stone. This will lead us, in
a natural way, to completely new insights into the theory of sandstorms.


title: Mini-Optics Solar Energy Concentrator

abstract:
  This invention deals with the broad general concept for focussing light. A
mini-optics tracking and focussing system is presented for solar power
conversion that ranges from an individual's portable system to solar conversion
of electrical power that can be used in large scale power plants for
environmentally clean energy. It can be rolled up, transported, and attached to
existing man-made, or natural structures. It allows the solar energy conversion
system to be low in capital cost and inexpensive to install as it can be
attached to existing structures since it does not require the construction of a
superstructure of its own. This novel system is uniquely distinct and different
from other solar tracking and focussing processes allowing it to be more
economical and practical. Furthermore, in its capacity as a power producer, it
can be utilized with far greater safety, simplicity, economy, and efficiency in
the conversion of solar energy.


title:
Ultrahigh Light Intensification by a Counter-Propagating Breaking Plasma
  Wave - Relativistic Flying Parabolic Mirror

abstract:
  A method to generate ultrahigh intense electromagnetic fields is suggested,
based on the laser pulse compression, carrier frequency upshift and focusing by
a counter-propagating breaking plasma wave, relativistic flying parabolic
mirror. This method allows us to achieve the quantum electrodynamics critical
field (Schwinger limit) with present day laser systems.

categories: physics.plasm-ph physics.comp-ph physics.gen-ph physics.space-ph


title:
Relativistic Whistle: High Order Harmonics Induced by the Ultra-Intense
  Laser Pulse Propagating inside the Fiber

abstract:
  A propagation of an ultra-intense short laser pulse in a fiber is
investigated with two dimensional Particle-in-Cell simulations. The fiber is a
narrow hollow channel with walls consisting of overdense plasma. In the
nonlinear interaction of the laser pulse with fiber walls high order harmonics
are generated. Sufficiently high harmonics, for which the fiber walls are
transparent, propagate outwards at certain angle. This is a scheme of a
generator of ultra-short pulses of coherent light with a very short wavelength.

categories: physics.plasm-ph physics.comp-ph physics.ins-det physics.optics


title:
On an Elementary Derivation of the Hamilton-Jacobi Equation from the
  Second Law of Newton

abstract:
  It is shown that for a relativistic particle moving in an electromagnetic
field its equations of motion written in a form of the second law of Newton can
be reduced with the help of elementary operations to the Hamilton-Jacobi
equation. The derivation is based on a possibility of transforming the equation
of motion to a completely antisymmetric form. Moreover, by perturbing the
Hamilton-Jacobi equation we obtain the principle of least action.\
  The analogous procedure is easily extended to a general relativistic motion
of a charged relativistic particle in an electromagnetic field. It sis also
shown that the special-relativistic Hamilton-Jacobi equation for a free
particle allows one to easily demonstrate the wave-particle duality inherent to
this equation and, in addition, to obtain the operators of the four-momentum
whose eigenvalues are the classical four-momentum


title: Approximations to path integrals and spectra of quantum systems

abstract:
  An expression for the Green function G(E;x_1,x_2) of the Schroedinger
equation is obtained through the approximations of the path integral by n-fold
multiple integrals. The approximations to Re{G(E;x,x)} on the real E-axis have
peaks near the values of the energy levels E_{j}. The analytic and numerical
examples for one-dimensional and multi-dimensional harmonic and anharmonic
oscillators, and Poeschl-Teller potential wells, show that median values of
these peaks for approximate G(E;0,0) corresponds with accuracy of order 10% to
the exact values of even levels already in the lowest orders of approximation
n=1 and n=2, i.e. when the path integral is replaced by a line or double
integral. The weights of the peaks approximate the values of the squared
modulus of the wave functions at x=0 with the same accuracy.

categories: physics.comp-ph hep-th physics.atom-ph quant-ph


title:
Nonlinear magneto-optical rotation of frequency-modulated light resonant
  with a low-J transition

abstract:
  A low-light-power theory of nonlinear magneto-optical rotation of
frequency-modulated light resonant with a J=1->J'=0 transition is presented.
The theory is developed for a Doppler-free transition, and then modified to
account for Doppler broadening and velocity mixing due to collisions. The
results of the theory are shown to be in qualitative agreement with
experimental data obtained for the rubidium D1 line.


title:
A Cascaded Iterative Fourier Transform Algorithm For Optical Security
  Applications

abstract:
  A cascaded iterative Fourier transform (CIFT) algorithm is presented for
optical security applications. Two phase-masks are designed and located in the
input and the Fourier domains of a 4-f correlator respectively, in order to
implement the optical encryption or authenticity verification. Compared with
previous methods, the proposed algorithm employs an improved searching
strategy: modifying the phase-distributions of both masks synchronously as well
as enlarging the searching space. Computer simulations show that the algorithm
results in much faster convergence and better image quality for the recovered
image. Each of these masks is assigned to different person. Therefore, the
decrypted image can be obtained only when all these masks are under
authorization. This key-assignment strategy may reduce the risk of being
intruded.


title: Probing complex RNA structures by mechanical force

abstract:
  RNA secondary structures of increasing complexity are probed combining single
molecule stretching experiments and stochastic unfolding/refolding simulations.
We find that force-induced unfolding pathways cannot usually be interpretated
by solely invoking successive openings of native helices. Indeed, typical
force-extension responses of complex RNA molecules are largely shaped by
stretching-induced, long-lived intermediates including non-native helices. This
is first shown for a set of generic structural motifs found in larger RNA
structures, and then for Escherichia coli's 1540-base long 16S ribosomal RNA,
which exhibits a surprisingly well-structured and reproducible unfolding
pathway under mechanical stretching. Using out-of-equilibrium stochastic
simulations, we demonstrate that these experimental results reflect the slow
relaxation of RNA structural rearrangements. Hence, micromanipulations of
single RNA molecules probe both their native structures and long-lived
intermediates, so-called "kinetic traps", thereby capturing -at the single
molecular level- the hallmark of RNA folding/unfolding dynamics.


title:
New features of modulational instability of partially coherent light;
  importance of the incoherence spectrum

abstract:
  It is shown that the properties of the modulational instability of partially
coherent waves propagating in a nonlinear Kerr medium depend crucially on the
profile of the incoherent field spectrum. Under certain conditions, the
incoherence may even enhance, rather than suppress, the instability. In
particular, it is found that the range of modulationally unstable wave numbers
does not necessarily decrease monotonously with increasing degree of
incoherence and that the modulational instability may still exist even when
long wavelength perturbations are stable.


title: Effective photon-photon interaction in a two-dimensional "photon fluid"

abstract:
  We formulate an effective theory for the atom-mediated photon-photon
interactions in a two-dimensional ``photon fluid'' confined in a Fabry-Perot
resonator. With the atoms modelled by a collection of anharmonic Lorentz
oscillators, the effective interaction is evaluated to second order in the
coupling constant (the anharmonicity parameter). The interaction has the form
of a renormalized two-dimensional delta-function potential, with the
renormalization scale determined by the physical parameters of the system, such
as density of atoms and the detuning of the photons relative to the resonance
frequency of the atoms. For realistic values of the parameters, the
perturbation series has to be resummed, and the effective interaction becomes
independent of the ``bare'' strength of the anharmonic term. The resulting
expression for the non-linear Kerr susceptibility, is parametrically equal to
the one found earlier for a dilute gas of two-level atoms. Using our result for
the effective interaction parameter, we derive conditions for the formation of
a photon fluid, both for Rydberg atoms in a microwave cavity and for alkali
atoms in an optical cavity.


title: Strong RF Focusing for Luminosity Increase

abstract:
  A luminosity of a circular collider can be increased by squeezing the bunch
length at the interaction point (IP). A natural way to decrease the bunch
length is to decrease the momentum compaction factor and/or to increase the RF
voltage. However, in such a way we cannot obtain short bunches with high
currents since wakefields prevent this due to the potential well distortion and
the microwave instability. In present paper we propose to use a strong RF
focusing (with high RF voltage and high momentum compaction factor) to obtain
very short bunches at the IP with progressive bunch elongation towards the RF
cavity. This allows placing the most important impedance generating elements
near the RF cavity where the bunch is longest thus minimizing the effect of the
wakefields.


title: Autler-Townes splitting in two-color photoassociation of 6Li

abstract:
  We report on high-resolution two-color photoassociation spectroscopy in the
triplet system of magneto-optically trapped 6Li. The absolute transition
frequencies have been measured. Strong optical coupling of the bound molecular
states has been observed as Autler-Townes splitting in the photoassociation
signal. The spontaneous bound-bound transition rate is determined and the
molecule formation rate is estimated. The observed lineshapes are in good
agreement with the theoretical model.


title: Spatially Differential Forms of Lenz Law

abstract:
  Two sets of spatially differential formulas of Lenz law on electromagnetic
inductance are presented. They are a cut-magnetic flux induced voltage, which
instantaneously results from cutting magnetic flux as a conductor moving with
respect to an external magnetic field, and a wave-induced voltage due to the
interaction of a conductor or charged particles with the arriving
electromagnetic wave, which is originated from a changing magnetic flux source.
Upon the Lenz differential forms, the induced electrical field strength,
relevant properties and their application are discussed.


title: Local phase structure of wave dislocation lines: twist and twirl

abstract:
  Generic wave dislocations (phase singularities, optical vortices) in three
dimensions have anisotropic local structure, which is analysed, with emphasis
on the twist of surfaces of equal phase along the singular line, and the
rotation of the local anisotropy ellipse (twirl). Various measures of twist and
twirl are compared in specific examples, and a theorem is found relating the
(quantised) topological twist and twirl for a closed dislocation loop with the
anisotropy C line index threading the loop.


title: Bound on Lorentz- and CPT-Violating Boost Effects for the Neutron

abstract:
  A search for an annual variation of a daily sidereal modulation of the
frequency difference between co-located ${}^{129}$Xe and ${}^{3}$He Zeeman
masers sets a stringent limit on boost-dependent Lorentz and CPT violation
involving the neutron, consistent with no effect at the level of 150 nHz. In
the framework of the general Standard-Model Extension, the present result
provides the first clean test for the fermion sector of the symmetry of
spacetime under boost transformations at a level of $10^{-27}$ GeV.

categories: physics.atom-ph hep-ex hep-ph physics.gen-ph


title:
A broadband Ytterbium-doped tunable fiber laser for 3He optical pumping
  at 1083 nm

abstract:
  Large amounts of hyperpolarized 3He gas with high nuclear polarization rates
are required for use in neutron spin filters or nuclear magnetic resonance
imaging of human lung. Very high efficiency can be obtained by metastability
exchange optical pumping using multimode lasers to excite the 23S-23P
transition at 1083 nm. Broadband Ytterbium-doped tunable fiber lasers have been
designed for that particular application. Different options for the
architecture of the fiber oscillator are presented and compared. Emphasis is
given to a linear cavity configuration that includes a high reflectivity fiber
mirror and a low reflectivity tunable fiber Bragg grating. Optical measurements
are performed to finely characterize the spectral behavior of the lasers.
Atomic response is also quantitatively probed to assess the optimal design of
the oscillator for optical pumping. Multimode operation matching the 2 GHz
Doppler-broadened helium resonance line and tunability over more than 200 GHz
are demonstrated. Boosting the output of this fiber laser with a Yb-doped fiber
power amplifier, all-fiber devices are built to provide robust, high power
turn-key sources at 1083 nm for improved production of laser polarized 3He.


title:
Extracting physics from an unphysical situation: light mesons in a small
  box

abstract:
  Quantum Chromo Dynamics is considered in a setup where the light mesons are
squeezed into unphysically small boxes. We show how such a situation can be
used to determine the couplings of the low energy chiral Lagrangian from
lattice simulations, applying chirally invariant formulations of lattice
fermions.


title:
Lagrangian turbulence in the Adriatic Sea as computed from drifter data:
  effects of inhomogeneity and nonstationarity

abstract:
  The properties of mesoscale Lagrangian turbulence in the Adriatic Sea are
studied from a drifter data set spanning 1990-1999, focusing on the role of
inhomogeneity and nonstationarity. A preliminary study is performed on the
dependence of the turbulent velocity statistics on bin averaging, and a
preferential bin scale of 0.25 is chosen. Comparison with independent estimates
obtained using an optimized spline technique confirms this choice. Three main
regions are identified where the velocity statistics are approximately
homogeneous: the two boundary currents, West (East) Adriatic Current, WAC
(EAC), and the southern central gyre, CG. The CG region is found to be
characterized by symmetric probability density function of velocity,
approximately exponential autocorrelations and well defined integral quantities
such as di usivity and time scale. The boundary regions, instead, are
significantly asymmetric with skewness indicating preferential events in the
direction of the mean flow. The autocorrelation in the along mean flow
direction is characterized by two time scales, with a secondary exponential
with slow decay time of 11-12 days particularly evident in the EAC region.
Seasonal partitioning of the data shows that this secondary scale is especially
prominent in the summer-fall season. Possible physical explanations for the
secondary scale are discussed in terms of low frequency fluctuations of
forcings and in terms of mean flow curvature inducing fluctuations in the
particle trajectories. Consequences of the results for transport modelling in
the Adriatic Sea are discussed.


title:
OCS in small para-hydrogen clusters: energetics and structure with N=1-8
  complexed hydrogen molecules

abstract:
  We determine the structure and energetics of complexes of the linear OCS
molecule with small numbers of para-hydrogen molecules, N=1-8, using zero
temperature quantum Monte Carlo methods. Ground state calculations are carried
out with importance-sampled rigid body diffusion Monte Carlo (IS-RBDMC) and
excited state calculations with the projection operator imaginary time spectral
evolution (POITSE) methodology. The ground states are found to be highly
structured, with a gradual build up of two axial rings as N increases to 8.
Analysis of the azimuthal density correlations around the OCS molecule shows
that these rings are quite delocalized for small N values, but become strongly
localized for N \geq 5 . Excited state calculations are made for a range of
total cluster angular momentum values and the rotational energy levels fitted
to obtain effective rotational and distortion constants of the complexed OCS
molecule as a function of cluster size N. Detailed analysis of these
spectroscopic constants indicates that the complexes of OCS with para-hydrogen
have an unusually rich variation in dynamical behavior, with sizes N=1-2
showing near rigid behavior, sizes N=3-4 showing extremely floppy behavior, and
the larger sizes N=5-8 showing more rigid behavior again. The large values of
the distortion constant D obtained for N=3-4 are rationalized in terms of the
coupling between the OCS rotations and the "breathing" mode of the first,
partially filled ring of para-hydrogen molecules.


title:
Ultimate limits to inertial mass sensing based upon
  nanoelectromechanical systems

abstract:
  Nanomechanical resonators can now be realized that achieve fundamental
resonance frequencies exceeding 1 GHz, with quality factors (Q) in the range
1,000 - 100,000. The minuscule active masses of these devices, in conjunction
with their high Qs, translate into unprecedented inertial mass sensitivities.
This makes them natural candidates for a variety of mass sensing applications.
Here we evaluate the ultimate mass sensitivity limits for nanomechanical
resonators operating in vacuo, which are imposed by a number of fundamental
physical noise processes. Our analyses indicate that nanomechanical resonators
offer immense potential for mass sensing - ultimately with resolution at the
level of individual molecules.


title: Collisional properties of trapped cold chromium atoms

abstract:
  We report on calculations of the elastic cross section and thermalization
rate for collision between two maximally spin-polarized chromium atoms in the
cold and ultracold regimes, relevant to buffer-gas and magneto-optical cooling
of chromium atoms. We calculate ab initio potential energy curves for Cr2 and
the van der Waals coefficient C6, and construct interaction potentials between
two colliding Cr atoms. We explore the effect of shape resonances on elastic
cross section, and find that they dramatically affect the thermalization rate.
Our calculated value for the s-wave scattering length is compared in magnitude
with a recent measurement at ultracold temperatures.


title: A comparison of methods for confidence intervals

abstract:
  Comparisons are carried out of the confidence intervals constructed with
Neyman's frequentist method and with the \Delta L=1/2 likelihood method, using
the example of low-statistics life time estimates.


title: Diffraction-free subwavelength-beam optics

abstract:
  Diffraction is a fundamental property of light propagation. Owing to this
phenomenon,light diffracts out in all directions when it passes through a
subwavelength slit.This imposes a fundamental limit on the transverse size of a
light beam at a given distance from the aperture. We show that a
subwavelength-sized beam propagating without diffractive broadening can be
produced in free space by the constructive interference of multiple beams of a
Fresnel source of the respective high-refraction-index waveguide. Moreover, it
is shown that such a source can be constructed not only for continuous waves,
but also for ultra-short (near single-cycle) pulses. The results theoretically
demonstrate the feasibility of completely diffraction-free subwavelength-beam
optics, for both continuous waves and ultra-short pulses. The approach extends
operation of the near-field subwavelength-beam optics, such as near-field
scanning optical microscopy and spectroscopy,to the "not-too-distant" field
regime (0.5 to about 10 wavelengths).


title:
Localized wave solutions of the scalar homogeneous wave equation and
  their optical implementation

abstract:
  In recent years the topic of localized wave solutions of the homogeneous
scalar wave equation, i.e., the wave fields that propagate without any
appreciable spread or drop in intensity, has been discussed in many aspects in
numerous publications. In this review the main results of this rather disperse
theoretical material are presented in a single mathematical representation -
the Fourier decomposition by means of angular spectrum of plane waves. This
unified description is shown to lead to a transparent physical understanding of
the phenomenon as such and yield the means of optical generation of such wave
fields.


title: A New Damping Mechanism in Non-linear Bubble Dynamics

abstract:
  Non-linear equations of radial motion of a gas bubble in a compressible
viscous liquid have been modified considering effects of viscosity and
compressibility more complete than all previous works. A new set of equations
has been derived including new terms resulted from consideration of the
viscosity and compressibility not only at the bubble interface, but also in the
bulk of liquid. The new equations are two non-linear coupled equations, which
can not be merged into one equation unlike all previously derived equations.
Numerical calculations have been performed considering effects of heat and mass
transfer at the bubble interface. The results indicate that the new terms
exhibit an important damping role at the collapse, so that their consideration
dramatically weakens the bubble rebounds after the collapse. Dependence of this
new damping mechanism to amplitude and frequency of the deriving pressure has
been investigated.


title:
Comparison of Rotational Energies and Rigidity of OCS-paraH_2 and
  OCS-4He complexes

abstract:
  We analyze the nature of the rotational energy level structure of the OCS-He
and OCS-H_2 complexes with a comparison of exact calculations to several
differentdynamical approximations. We compare with the clamped coordinate
quasiadiabatic approximation that introduces an effective potential for each
asymmetric rotor level, with an effective rotation Hamiltonian constructed from
ground state averages of the inverse of the inertial matrix, and investigate
the usefulness of the Eckart condition to decouple rotations and vibrations of
these weakly bound complexes between linear OCS and 4He or H_2. Comparison with
exact results allows an assessment of the accuracies of the different
approximate methods and indicates which approaches are suitable for larger
clusters of OCS with 4He and with H_2. We find the OCS-H_2 complex is
considerably more rigid than the OCS-4He complex, suggesting that semi-rigid
models are useful for analysis of larger clusters of H_2 with OCS.


title:
A New Monomeric Interpretation of Intrinsic Optical Bistability Observed
  in Yb3+ - Doped Bromide Materials

abstract:
  We present a mechanism able to show intrinsic bistable behaviour involving
single Yb3+ ions embedded into bromide lattices, in which intrinsic optical
bistability (IOB) has been observed. The mechanism is based on the
experimentally found coupling between the Yb3+ ion and the totally symmetric
local mode of vibration of the [YbBr6]3- coordination unit. The model
reproduces the IOB observed in CsCdBr3:1% Yb3+ and allows to understand the
experimentally found presence of the phenomenon in the other bromides, but its
absence in Cs3Lu2Cl9:Yb3+.


title:
Classical Scattering for a driven inverted Gaussian potential in terms
  of the chaotic invariant set

abstract:
  We study the classical electron scattering from a driven inverted Gaussian
potential, an open system, in terms of its chaotic invariant set. This chaotic
invariant set is described by a ternary horseshoe construction on an
appropriate Poincare surface of section. We find the development parameters
that describe the hyperbolic component of the chaotic invariant set. In
addition, we show that the hierarchical structure of the fractal set of
singularities of the scattering functions is the same as the structure of the
chaotic invariant set. Finally, we construct a symbolic encoding of the
hierarchical structure of the set of singularities of the scattering functions
and use concepts from the thermodynamical formalism to obtain one of the
measures of chaos of the fractal set of singularities, the topological entropy.


title: Localized and stationary light wave modes in dispersive media

abstract:
  In recent experiments, localized and stationary pulses have been generated in
second-order nonlinear processes with femtosecond pulses, whose asymptotic
features relate with those of nondiffracting and nondispersing polychromatic
Bessel beams in linear dispersive media. We investigate on the nature of these
linear waves, and show that they can be identified with the X-shaped (O-shaped)
modes of the hyperbolic (elliptic) wave equation in media with normal
(anomalous) dispersion. Depending on the relative strengths of mode phase
mismatch, group velocity mismatch with respect to a plane pulse, and of the
defeated group velocity dispersion, these modes can adopt the form of pulsed
Bessel beams, focus wave modes, and X-waves (O-waves), respectively.


title:
Blending of nanoscale and microscale in uniform large-area sculptured
  thin-film architectures

abstract:
  The combination of large thickness ($>3$ $\mu$m), large--area uniformity (75
mm diameter), high growth rate (up to 0.4 $\mu$m/min) in assemblies of
complex--shaped nanowires on lithographically defined patterns has been
achieved for the first time. The nanoscale and the microscale have thus been
blended together in sculptured thin films with transverse architectures.
SiO$_x$ ($x\approx 2$) nanowires were grown by electron--beam evaporation onto
silicon substrates both with and without photoresist lines (1--D arrays) and
checkerboard (2--D arrays) patterns. Atomic self--shadowing due to
oblique--angle deposition enables the nanowires to grow continuously, to change
direction abruptly, and to maintain constant cross--sectional diameter. The
selective growth of nanowire assemblies on the top surfaces of both 1--D and
2--D arrays can be understood and predicted using simple geometrical shadowing
equations.


title: Modified conjugated gradient method for diagonalising large matrices

abstract:
  We present an iterative method to diagonalise large matrices. The basic idea
is the same as the conjugated gradient (CG) method, i.e, minimizing the
Rayleigh quotient via its gradient and avoiding reintroduce errors to the
directions of previous gradients. Each iteration step is to find lowest
eigenvector of the matrix in a subspace spanned by the current trial vector and
the corresponding gradient of the Rayleigh quotient, as well as some previous
trial vectors. The gradient, together with the previous trail vectors, play a
similar role of the conjugated gradient of the original CG algorithm. Our
numeric tests indicate that this method converges significantly faster than the
original CG method. And the computational cost of one iteration step is about
the same as the original CG method. It is suitably for first principle
calculations.


title: Celestial mechanics, from high-school to Newton's Principia

abstract: A high-school exercise is used to get an insight into planetary motion.


title:
Doppler shift experiments with source in periodic motion: Parametrized
  Doppler shift formulas

abstract:
  Doppler shift formulas are derived for two less studied scenarios: stationary
receiver and source in harmonic oscillatory motion and stationary receiver and
source in uniform circular motion. For each of the scenarios we derive a
formula, one which works when the emission period is small enough that it can
be considered that two successive signals are emitted from the same point in
space (locality assumption) and another which takes into account that two
successive signals are emitted from two different points in space (non-locality
assumption). The results furnished by the two Doppler shift formulas are
compared, showing that increasing the emission frequency decreases the
difference between the results obtained with the two formulas.


title:
About some Information and Logical Properties of Semiconductor
  Multistable Plazma

abstract:
  Some information and logical properties of multistable semi-conductor plazma
are discussed and the concept of physical logic system Lp on their basis is
entered. Lp contains exclusively values of some quantitative characteristic
physical size of plazma and transformation of a set of such sizes by means of
plazma-field interaction. The opportunity nonmathematical (physical)
calculation in Lp is considered and as an example by symbols Lp are submitted
classical arithmetic-logic actions, i.e. their physical models in system Lp are
found.


title:
Application of Sharafutdinov's Ray Transform in Integrated
  Photoelasticity

abstract:
  We explain the main concepts centered around Sharafutdinov's ray transform,
its kernel, and the extent to which it can be inverted. It is shown how the ray
transform emerges naturally in any attempt to reconstruct optical and stress
tensors within a photoelastic medium from measurements on the state of
polarization of light beams passing through the strained medium. The problem of
reconstruction of stress tensors is crucially related to the fact that the ray
transform has a nontrivial kernel; the latter is described by a theorem for
which we provide a new proof which is simpler and shorter as in Sharafutdinov's
original work, as we limit our scope to tensors which are relevant to
Photoelasticity. We explain how the kernel of the ray transform is related to
the decomposition of tensor fields into longitudinal and transverse components.
The merits of the ray transform as a tool for tensor reconstruction are studied
by walking through an explicit example of reconstructing the
$\sigma_{33}$-component of the stress tensor in a cylindrical photoelastic
specimen. In order to make the paper self-contained we provide a derivation of
the basic equations of Integrated Photoelasticity which describe how the
presence of stress within a photoelastic medium influences the passage of
polarized light through the material.


title: On Dirac's magnetic monopole

abstract:
  The electric charge of the quantization condition of Dirac's monopole may
have any value, we are not obliged to identify it with the electron charge.
Consequently the magnetic charge of the monopole is quite arbitrary: Dirac's
monopole is a mere object of science fiction.


title: Alternative potentials for the electromagnetic field

abstract:
  The electromagnetic field can be expressed in terms of two complex potentials
$ \alpha, \beta ,$ which are related to the Debye potentials. The evolution
equations for these potentials are derived, which are separable either in
parabolic coordinates (leading to the radiation fields) or in radial
coordinates (multipole fields). Potentials corresponding to focused wave fields
as well as plane waves are discussed. A conserved radiation density can be
constructed in terms of these potentials, which is positive (negative) for
positive (negative) helicity radiation.


title:
Interdimensional degeneracies for a quantum $N$-body system in $D$
  dimensions

abstract:
  Complete spectrum of exact interdimensional degeneracies for a quantum
$N$-body system in $D$-dimensions is presented by the method of generalized
spherical harmonic polynomials. In an $N$-body system all the states with
angular momentum $[\mu+n]$ in $(D-2n)$ dimensions are degenerate where $[\mu]$
and $D$ are given and $n$ is an arbitrary integer if the representation
$[\mu+n]$ exists for the SO($D-2n$) group and $D-2n\geq N$. There is an
exceptional interdimensional degeneracy for an $N$-body system between the
state with zero angular momentum in $D=N-1$ dimensions and the state with zero
angular momentum in $D=N+1$ dimensions.


title:
Metastable level lifetimes from electron-shelving measurements with ion
  clouds and single ions

abstract:
  The lifetime of the 3d^2D_5/2-level in singly-ionized calcium has been
measured by the electron-shelving technique on different samples of rf trapped
ions. The metastable state has been directly populated by exciting the
dipole-forbidden 4S_1/2 - 3D_5/2 transition. In ion clouds, the natural
lifetime of this metastable level has been measured to be (1095+-27) ms. For
the single-ion case, we determined a lifetime of (1152+-20) ms. The
1sigma-error bars at the 2%-level have different origins for the two kinds of
experiments: data fitting methods for lifetime measurements in an ion cloud and
control of experimental parameters for a single ion. De-shelving effects are
extensively discussed. The influence of differing approaches for the processing
of the single-ion quantum jump data on the lifetime values is shown. Comparison
with recent measurements shows excellent agreement when evaluated from a given
method.


title: Saturation induced coherence loss in coherent backscattering of light

abstract:
  We use coherent backscattering (CBS) of light by cold Strontium atoms to
study the mutual coherence of light waves in the multiple scattering regime. As
the probe light intensity is increased, the atomic optical transition starts to
be saturated. Nonlinearities and inelastic scattering then occur. In our
experiment, we observe a strongly reduced enhancement factor of the coherent
backscattering cone when the intensity of the probe laser is increased,
indicating a partial loss of coherence in multiple scattering.


title:
Insights from a Novel Tumor Model: Indications for a Quantitative Link
  between Tumor Growth and Invasion

abstract:
  Using our previously developed model we demonstrate here, that (1) solid
tumor growth and cell invasion are linked, not only qualitatively but also
quantitatively, that (2) the onset of invasion marks the time point when the
tumor cell density exceeds a compaction maximum, and that (3) tumor cell
invasion, reduction of mechanical confinement and angiogenesis can act
synergistically to increase the actual tumor mass towards the level predicted
by West et al. universal growth curve.