title:
Long-term investigations of radiocaesium activity concentrations in
  carps in north Croatia after the Chernobyl accident

abstract:
  Long-term investigations of radiocaesium activity concentrations in carps in
the Republic of Croatia are presented. The radiocaesium levels in carps
decreased exponentially and the effective ecological half-life of 137Cs in
carps was estimated to be about 1 year for 1987-2002 period and 5 years for
1993-2005 period. The observed 134Cs:137Cs activity ratio in carps has been
found to be similar to the ratio that has been observed in other environmental
samples. Concentration factor for carps (wet weight) was roughly estimated to
be 128 +/- 74 Lkg-1, which is in reasonable agreement with model prediction
based on K+ concentrations in water. Estimated annual effective doses received
by 134Cs and 137Cs intake due to consumption of carps for an adult member of
Croatian population are small, per caput dose for the 1987 - 2005 estimated to
be 0.5 +/- 0.2 microSv. Due to minor freshwater fish consumption in Croatia and
low radiocaesium activity concentrations in carps, it can be concluded that
carps consumption was not a critical pathway for the transfer of radiocaesium
from fallout to humans after the Chernobyl accident.


title: Phase transitions in social networks

abstract:
  We study a model of network with clustering and desired node degree. The
original purpose of the model was to describe optimal structures of scientific
collaboration in the European Union. The model belongs to the family of
exponential random graphs. We show by numerical simulations and analytical
considerations how a very simple Hamiltonian can lead to surprisingly
complicated and eventful phase diagram.


title:
A two-frequency acousto-optic modulator driver to improve the beam
  pointing stability during intensity ramps

abstract:
  We report on a scheme to improve the pointing stability of the first order
beam diffracted by an acousto-optic modulator (AOM). Due to thermal effects
inside the crystal, the angular position of the beam can change by as much as 1
mrad when the radio-frequency power in the AOM is reduced to decrease the first
order beam intensity. This is done for example to perform forced evaporative
cooling in ultracold atom experiments using far-off-resonant optical traps. We
solve this problem by driving the AOM with two radio-frequencies $f_1$ and
$f_2$. The power of $f_2$ is adjusted relative to the power of $f_1$ to keep
the total power constant. Using this, the beam displacement is decreased by a
factor of twenty. The method is simple to implement in existing experimental
setups, without any modification of the optics.


title:
Splitting of Resonant Frequencies of Acoustic Waves in Rotating
  Compressible Fluid

abstract:
  It is shown that in a rotating compressible fluid the resonant frequencies
(measured in a system of reference rotating together with the medium) for the
azimuthally running acoustic waves are split into two components. The received
results can be of practical significance as a basis of a method of measurements
of angular speed of medium and for acoustics of rotating technical devices.


title: On the extrapolation to ITER of discharges in present tokamaks

abstract:
  An expression for the extrapolated fusion gain G = Pfusion /5 Pheat (Pfusion
being the total fusion power and Pheat the total heating power) of ITER in
terms of the confinement improvement factor (H) and the normalised beta (betaN)
is derived in this paper. It is shown that an increase in normalised beta can
be expected to have a negative or neutral influence on G depending on the
chosen confinement scaling law. Figures of merit like H betaN / q95^2 should be
used with care, since large values of this quantity do not guarantee high
values of G, and might not be attainable with the heating power installed on
ITER.


title:
The Effect of Laser Focusing Conditions on Propagation and Monoenergetic
  Electron Production in Laser Wakefield Accelerators

abstract:
  The effect of laser focusing conditions on the evolution of relativistic
plasma waves in laser wakefield accelerators is studied both experimentally and
with particle-in-cell simulations. For short focal length ($w_0 < \lambda_p$)
interactions, beam break-up prevents stable propagation of the pulse. High
field gradients lead to non-localized phase injection of electrons, and thus
broad energy spread beams. However for long focal length geometries ($w_0 >
\lambda_p$), a single optical filament can capture the majority of the laser
energy, and self-guide over distances comparable to the dephasing length, even
for these short-pulses ($c\tau \approx \lambda_p$). This allows the wakefield
to evolve to the correct shape for the production of the monoenergetic electron
bunches, as measured in the experiment.


title:
Measurement of excited-state transitions in cold calcium atoms by direct
  femtosecond frequency-comb spectroscopy

abstract:
  We apply direct frequency-comb spectroscopy, in combination with precision cw
spectroscopy, to measure the ${\rm 4s4p} ^3P_1 \to {\rm 4s5s} ^3S_1$ transition
frequency in cold calcium atoms. A 657 nm ultrastable cw laser was used to
excite atoms on the narrow ($\gamma \sim 400$ Hz) ${\rm 4s^2} ^1S_0 \to {\rm
4s4p} ^3P_1$ clock transition, and the direct output of the frequency comb was
used to excite those atoms from the ${\rm 4s4p} ^3P_1$ state to the ${\rm 4s5s}
^3S_1$ state. The resonance of this second stage was detected by observing a
decrease in population of the ground state as a result of atoms being optically
pumped to the metastable ${\rm 4s4p} ^3P_{0,2}$ states. The ${\rm 4s4p} ^3P_1
\to {\rm 4s5s} ^3S_1$ transition frequency is measured to be $\nu = 489 544 285
713(56)$ kHz; which is an improvement by almost four orders of magnitude over
the previously measured value. In addition, we demonstrate spectroscopy on
magnetically trapped atoms in the ${\rm 4s4p} ^3P_2$ state.


title: Parallel MRI at microtesla fields

abstract:
  Parallel imaging techniques have been widely used in high-field magnetic
resonance imaging (MRI). Multiple receiver coils have been shown to improve
image quality and allow accelerated image acquisition. Magnetic resonance
imaging at ultra-low fields (ULF MRI) is a new imaging approach that uses SQUID
(superconducting quantum interference device) sensors to measure the spatially
encoded precession of pre-polarized nuclear spin populations at
microtesla-range measurement fields. In this work, parallel imaging at
microtesla fields is systematically studied for the first time. A seven-channel
SQUID system, designed for both ULF MRI and magnetoencephalography (MEG), is
used to acquire 3D images of a human hand, as well as 2D images of a large
water phantom. The imaging is performed at 46 microtesla measurement field with
pre-polarization at 40 mT. It is shown how the use of seven channels increases
imaging field of view and improves signal-to-noise ratio for the hand images. A
simple procedure for approximate correction of concomitant gradient artifacts
is described. Noise propagation is analyzed experimentally, and the main source
of correlated noise is identified. Accelerated imaging based on one-dimensional
undersampling and 1D SENSE (sensitivity encoding) image reconstruction is
studied in the case of the 2D phantom. Actual 3-fold imaging acceleration in
comparison to single-average fully encoded Fourier imaging is demonstrated.
These results show that parallel imaging methods are efficient in ULF MRI, and
that imaging performance of SQUID-based instruments improves substantially as
the number of channels is increased.


title: Assessing symmetry of financial returns series

abstract:
  Testing symmetry of a probability distribution is a common question arising
from applications in several fields. Particularly, in the study of observables
used in the analysis of stock market index variations, the question of symmetry
has not been fully investigated by means of statistical procedures. In this
work a distribution-free test statistic Tn for testing symmetry, derived by
Einmahl and McKeague, based on the empirical likelihood approach, is used to
address the study of symmetry of financial returns. The asymptotic points of
the test statistic Tn are also calculated and a procedure for assessing
symmetry for the analysis of the returns of stock market indices is presented.


title:
Networks of Recurrent Events, a Theory of Records, and an Application to
  Finding Causal Signatures in Seismicity

abstract:
  We propose a method to search for signs of causal structure in spatiotemporal
data making minimal a priori assumptions about the underlying dynamics. To this
end, we generalize the elementary concept of recurrence for a point process in
time to recurrent events in space and time. An event is defined to be a
recurrence of any previous event if it is closer to it in space than all the
intervening events. As such, each sequence of recurrences for a given event is
a record breaking process. This definition provides a strictly data driven
technique to search for structure. Defining events to be nodes, and linking
each event to its recurrences, generates a network of recurrent events.
Significant deviations in properties of that network compared to networks
arising from random processes allows one to infer attributes of the causal
dynamics that generate observable correlations in the patterns. We derive
analytically a number of properties for the network of recurrent events
composed by a random process. We extend the theory of records to treat not only
the variable where records happen, but also time as continuous. In this way, we
construct a fully symmetric theory of records leading to a number of new
results. Those analytic results are compared to the properties of a network
synthesized from earthquakes in Southern California. Significant disparities
from the ensemble of acausal networks that can be plausibly attributed to the
causal structure of seismicity are: (1) Invariance of network statistics with
the time span of the events considered, (2) Appearance of a fundamental length
scale for recurrences, independent of the time span of the catalog, which is
consistent with observations of the ``rupture length'', (3) Hierarchy in the
distances and times of subsequent recurrences.

categories: physics.data-an cond-mat.stat-mech math.ST nlin.PS physics.geo-ph stat.TH


title:
Increasing the coherence time of Bose-Einstein-condensate
  interferometers with optical control of dynamics

abstract:
  Atom interferometers using Bose-Einstein condensate that is confined in a
waveguide and manipulated by optical pulses have been limited by their short
coherence times. We present a theoretical model that offers a physically simple
explanation for the loss of contrast and propose the method for increasing the
fringe contrast by recombining the atoms at a different time. A simple,
quantitatively accurate, analytical expression for the optimized recombination
time is presented and used to place limits on the physical parameters for which
the contrast may be recovered.


title:
Electron/pion separation with an Emulsion Cloud Chamber by using a
  Neural Network

abstract:
  We have studied the performance of a new algorithm for electron/pion
separation in an Emulsion Cloud Chamber (ECC) made of lead and nuclear emulsion
films. The software for separation consists of two parts: a shower
reconstruction algorithm and a Neural Network that assigns to each
reconstructed shower the probability to be an electron or a pion. The
performance has been studied for the ECC of the OPERA experiment [1].
  The $e/\pi$ separation algorithm has been optimized by using a detailed Monte
Carlo simulation of the ECC and tested on real data taken at CERN (pion beams)
and at DESY (electron beams). The algorithm allows to achieve a 90% electron
identification efficiency with a pion misidentification smaller than 1% for
energies higher than 2 GeV.


title: Effect of local pumping on random laser modes

abstract:
  We have developed a numerical method based on the transfer matrix to
calculate the quasimodes and lasing modes in one-dimensional random systems.
Depending on the relative magnitude of the localization length versus the
system size, there are two regimes in which the quasimodes are distinct in
spatial profile and frequency distribution. In the presence of uniform gain,
the lasing modes have one-to-one correspondence to the quasimodes in both
regimes. Local excitation may enhance the weight of a mode within the gain
region due to local amplification, especially in a weakly scattering system.


title:
Heteronuclear ionizing collisions between laser-cooled metastable helium
  atoms

abstract:
  We have investigated cold ionizing heteronuclear collisions in dilute
mixtures of metastable (2 3S1) 3He and 4He atoms, extending our previous work
on the analogous homonuclear collisions [R. J. W. Stas et al., PRA 73, 032713
(2006)]. A simple theoretical model of such collisions enables us to calculate
the heteronuclear ionization rate coefficient, for our quasi-unpolarized gas,
in the absence of resonant light (T = 1.2 mK): K34(th) = 2.4*10^-10 cm^3/s.
This calculation is supported by a measurement of K34 using magneto-optically
trapped mixtures containing about 1*10^8 atoms of each species, K34(exp) =
2.5(8)*10^-10 cm^3/s. Theory and experiment show good agreement.


title: The D0 Run II Impact Parameter Trigger

abstract:
  Many physics topics to be studied by the D0 experiment during Run II of the
Fermilab Tevatron ppbar collider give rise to final states containing
b--flavored particles. Examples include Higgs searches, top quark production
and decay studies, and full reconstruction of B decays. The sensitivity to such
modes has been significantly enhanced by the installation of a silicon based
vertex detector as part of the DO detector upgrade for Run II. Interesting
events must be identified initially in 100-200 microseconds to be available for
later study. This paper describes custom electronics used in the DO trigger
system to provide the real--time identification of events having tracks
consistent with the decay of b--flavored particles.


title:
Application of Macro Response Monte Carlo method for electron spectrum
  simulation

abstract:
  During the past years several variance reduction techniques for Monte Carlo
electron transport have been developed in order to reduce the electron
computation time transport for absorbed dose distribution. We have implemented
the Macro Response Monte Carlo (MRMC) method to evaluate the electron spectrum
which can be used used as a phase space input for others simulation programs.
Such technique uses probability distributions for electron histories previously
simulated in spheres (called kugels). These probabilities are used to sample
the primary electron final state, as well as the creation secondary electrons
and photons. We have compared the MRMC electron spectra simulated in
homogeneous phantom against the Geant4 spectra. The results showed an agreement
better than 6% in the spectra peak energies and that MRMC code is up to 12
times faster than Geant4 simulations.


title:
Current sheets at three-dimensional magnetic nulls: Effect of
  compressibility

abstract:
  The nature of current sheet formation in the vicinity of three-dimensional
(3D) magnetic null points is investigated. The particular focus is upon the
effect of the compressibility of the plasma on the qualitative and quantitative
properties of the current sheet. An initially potential 3D null is subjected to
shearing perturbations, as in a previous paper [Pontin et al., Phys. Plasmas,
in press (2007)]. It is found that as the incompressible limit is approached,
the collapse of the null point is suppressed, and an approximately planar
current sheet aligned to the fan plane is present instead. This is the case
regardless of whether the spine or fan of the null is sheared. Both the peak
current and peak reconnection rate are reduced. The results have a bearing on
previous analytical solutions for steady-state reconnection in incompressible
plasmas, implying that fan current sheet solutions are dynamically accessible,
while spine current sheet solutions are not.


title:
Gadolinium Iron Garnet as a Solid State Material for an Electron
  Electric Dipole Moment Search

abstract:
  The possibility of a solid state electron electric dipole moment (EDM)
experiment based on Gadolinium Iron Garnet (GdIG) is investigated. GdIG appears
to exhibit superparamagnetism and this effect can be used to enhance the
electric-field-induced EDM signal at relatively a high temperatures, as
compared to a simple paramagnetic system such as Gadolinium Gallium Garnet. The
sensitivity of a GdIG based experiment might be large enough that an
improvement by over three orders of magnitude, compared to the existing
electron EDM limit, could be obtained at a modest temperature of 4 K, assuming
that the superparamagnetic effect is not suppressed at this temperature, and
that the spin relaxation time remains sufficiently rapid.


title: Treatment of Errors in Efficiency Calculations

abstract:
  In this report we discuss the treatment of statistical errors in cut
efficiencies. The two commonly used methods for the calculation of the errors,
Poissonian and Binomial, are shown to be defective. We derive the form of the
underlying probability density function and characterize its mean, mode, and
variance. A method for the calculation of errors based on the variance of the
distribution is discussed.


title: Real Time Relativity: exploration learning of special relativity

abstract:
  Real Time Relativity is a computer program that lets students fly at
relativistic speeds though a simulated world populated with planets, clocks,
and buildings. The counterintuitive and spectacular optical effects of
relativity are prominent, while systematic exploration of the simulation allows
the user to discover relativistic effects such as length contraction and the
relativity of simultaneity. We report on the physics and technology
underpinning the simulation, and our experience using it for teaching special
relativity to first year university students.


title:
Signatures of two-dimensionalisation of 3D turbulence in presence of
  rotation

abstract:
  A reason has been given for the inverse energy cascade in the
two-dimensionalised rapidly rotating 3D incompressible turbulence. For such
system, literature shows a possibility of the exponent of wavenumber in the
energy spectrum's relation to lie between -2 and -3. We argue the existence of
a more strict range of -2 to -7/3 for the exponent in the case of rapidly
rotating turbulence which is in accordance with the recent experiments. Also, a
rigorous derivation for the two point third order structure function has been
provided helping one to argue that even with slow rotation one gets, though
dominated, a spectrum with the exponent -2.87, thereby hinting at the
initiation of the two-dimensionalisation effect with rotation.


title:
A mathematical model of DNA degradation: Possible role of magnetic
  nanoparticles

abstract:
  A mathematical model of genome degradation is proposed that takes into
account a variable rate of mutation and increasing number of cells in a
developing human organism. The model explains known properties of cancer
development, in particular, a synergism between different mutagens and an
increased probability of cancer in the early years of life. An iteration
equation is suggested that uses only a few model parameters and describes basic
regularities observed in cancer onset. In the model context, relatively small
chronic variations in the intracellular content of free radicals may markedly
affect the probability of a cell to become a cancer cell. On the other hand,
magnetic nanoparticles are shown to be an endogenous source of chronic magnetic
exposure that increases the local concentration of free radicals. An enhanced
level of leukaemia in early childhood is assumed to originate from magnetic
nanoparticles located in hematopoietic stem cells.


title: The Dynamics of Crowd Disasters: An Empirical Study

abstract:
  Many observations in the dynamics of pedestrian crowds, including various
self-organization phenomena, have been successfully described by simple
many-particle models. For ethical reasons, however, there is a serious lack of
experimental data regarding crowd panic. Therefore, we have analyzed video
recordings of the crowd disaster in Mina/Makkah during the Hajj in 1426H on
January 12, 2006. They reveal two subsequent, sudden transitions from laminar
to stop-and-go and ``turbulent'' flows, which question many previous simulation
models. While the transition from laminar to stop-and-go flows supports a
recent model of bottleneck flows [D. Helbing et al., Phys. Rev. Lett. 97,
168001 (2006)], the subsequent transition to turbulent flow is not yet well
understood. It is responsible for sudden eruptions of pressure release
comparable to earthquakes, which cause sudden displacements and the falling and
trampling of people. The insights of this study into the reasons for critical
crowd conditions are important for the organization of safer mass events. In
particularly, they allow one to understand where and when crowd accidents tend
to occur. They have also led to organizational changes, which have ensured a
safe Hajj in 1427H.


title: Dynamical affinity in opinion dynamics modelling

abstract:
  We here propose a model to simulate the process of opinion formation, which
accounts for the mutual affinity between interacting agents. Opinion and
affinity evolve self-consistently, manifesting a highly non trivial interplay.
A continuous transition is found between single and multiple opinion states.
Fractal dimension and signature of critical behaviour are also reported. A rich
phenomenology is presented and discussed with reference to corresponding
psychological implications.


title:
Radiocaesium Activity Concentrations in Potatoes in Croatia after the
  Chernobyl Accident and Dose Assessment

abstract:
  Systematic investigations of 137Cs and 134Cs activity concentrations in
potatoes (Solanum tuberosum) for the post-Chernobyl period (1986-2005) in the
Republic of Croatia are summarized. The correlation between 137Cs activity
concentrations in fallout and potatoes, has been found to be very good, the
correlation coefficient being r2=0.88 with P(t) < 0.001 for 18 degrees of
freedom. As the radiocaesium levels in potatoes decreased exponentially, the
mean residence time of 137Cs in potatoes was estimated by fitting the measured
activity concentrations to the exponential curve. The mean residence time was
found to be 6.8 +/- 1.1 years, the standard deviation being estimated by the
Monte Carlo simulations. The initial observed 134Cs:137Cs activity ratio in
potatoes has been found to be quite variable, but slightly lesser than
theoretically predicted value of 0.5, calculated by applying the known
inventory of these radionuclides in the Chernobyl reactor to the equation for
the differential radioactive decay. This can be explained by presence of the
pre-Chernobyl 137Cs in soil that originated from nuclear fallout. The annual
effective doses received by 134Cs and 137Cs intake due to consumption of
potatoes estimated for an adult member of Croatian population were found to be
very small, as the per caput dose for the entire 1986 - 2005 period was
calculated to be about 2.9 mSv, 134Cs accounting approximately for 1/3 of the
entire dose. Therefore, after the Chernobyl accident consumption of potatoes
was not the critical pathway for human intake of radiocaesium from the
environment in Croatia.


title: Theory of nuclear excitation by electron capture for heavy ions

abstract:
  We investigate the resonant process of nuclear excitation by electron
capture, in which a continuum electron is captured into a bound state of an ion
with the simultaneous excitation of the nucleus. In order to derive the cross
section a Feshbach projection operator formalism is introduced. Nuclear states
and transitions are described by a nuclear collective model and making use of
experimental data. Transition rates and total cross sections for NEEC followed
by the radiative decay of the excited nucleus are calculated for various heavy
ion collision systems.


title:
Quantum interference between nuclear excitation by electron capture and
  radiative recombination

abstract:
  We investigate the quantum interference between the resonant process of
nuclear excitation by electron capture (NEEC) followed by the radiative decay
of the excited nucleus, and radiative recombination (RR). In order to derive
the interference cross section, a Feshbach projection operator formalism is
used. The electromagnetic field is considered by means of multipole fields. The
nucleus is described by a phenomenological collective model and by making use
of experimental data. The Fano profile parameters as well as the interference
cross section for electric and magnetic multipole transitions in various heavy
ions are presented. We discuss the experimental possibility of discerning NEEC
from the RR background.


title:
Photon angular distribution and nuclear-state alignment in nuclear
  excitation by electron capture

abstract:
  The alignment of nuclear states resonantly formed in nuclear excitation by
electron capture (NEEC) is studied by means of a density matrix technique. The
vibrational excitations of the nucleus are described by a collective model and
the electrons are treated in a relativistic framework. Formulas for the angular
distribution of photons emitted in the nuclear relaxation are derived. We
present numerical results for alignment parameters and photon angular
distributions for a number of heavy elements in the case of E2 nuclear
transitions. Our results are intended to help future experimental attempts to
discern NEEC from radiative recombination, which is the dominant competing
process.


title:
Photonic superdiffusive motion in resonance line radiation trapping -
  partial frequency redistribution effects

abstract:
  The relation between the jump length probability distribution function and
the spectral line profile in resonance atomic radiation trapping is considered
for Partial Frequency Redistribution (PFR) between absorbed and reemitted
radiation. The single line Opacity Distribution Function [M.N. Berberan-Santos
et.al. J.Chem.Phys. 125, 174308 (2006)] is generalized for PFR and used to
discuss several possible redistribution mechanisms (pure Doppler broadening,
combined natural and Doppler broadening and combined Doppler, natural and
collisional broadening). It is shown that there are two coexisting scales with
a different behavior: the small scale is controlled by the intricate PFR
details while the large scale is essentially given by the atom rest frame
redistribution asymptotic. The pure Doppler and combined natural, Doppler and
collisional broadening are characterized by both small and large scale
superdiffusive Levy flight behaviors while the combined natural and Doppler
case has an anomalous small scale behavior but a diffusive large scale
asymptotic. The common practice of assuming complete redistribution in core
radiation and frequency coherence in the wings of the spectral distribution is
incompatible with the breakdown of superdiffusion in combined natural and
Doppler broadening conditions.


title: Lacunar fractal photon sieves

abstract:
  We present a new family of diffractive lenses whose structure is based on the
combination of two concepts: photon sieve and fractal zone plates with variable
lacunarity. The focusing properties of different members of this family are
examined. It is shown that the sieves provide a smoothing effect on the higher
order foci of a conventional lacunar fractal zone plate. However, the
characteristic self-similar axial response of the fractal zone plates is always
preserved.


title:
Fractal zone plates for wideband imaging with low chromatic aberration
  and extended depth of field

abstract:
  Fresnel zone plates are diffractive elements that are essential to form
images in many scientific and technological areas, especially where refractive
optics is not available. One of the main shortcomings of Fresnel zone plates,
which limit their utility with broadband sources, is their high chromatic
aberration. Recently presented, Fractal Zone Plates (FZPs) are diffractive
lenses characterized by an extended focal depth with a fractal structure. This
behaviour predicts an improved performance of FZPs as image forming devices
with an extended depth of field and a reduced chromatic aberration. Here we
report the achievement of the first polychromatic images obtained with a FZP
that confirm these predictions. We show that the polychromatic modulation
transfer function (MTF) of a FZP affected by defocus is about two times better
than one corresponding to a Fresnel zone plate. This result opens the
possibility to improve imaging techniques that use conventional Fresnel zone
plates over a wide range of the electromagnetic spectrum, ranging from x-rays
to THz.


title: On the geometry of Hamiltonian chaos

abstract:
  We show that Gutzwiller's characterization of chaotic Hamiltonian systems in
terms of the curvature associated with a Riemannian metric tensor in the
structure of the Hamiltonian can be extended to a wide class of potential
models of standard form through definition of a conformal metric. The geodesic
equations reproduce the Hamilton equations of the original potential model when
a transition is made to the dual manifold, and the geodesics in the dual space
coincide with the orbits of the Hamiltonian potential model. We therefore find
a direct geometrical description of the time development of a Hamiltonian
potential model. The second covariant derivative of the geodesic deviation in
this dual manifold generates a dynamical curvature, resulting in (energy
dependent) criteria for unstable behavior different from the usual Lyapunov
criteria. We discuss some examples of unstable Hamiltonian systems in two
dimensions giving, in particular, detailed results for a potential obtained
from a fifth order expansion of a Toda lattice Hamiltonian.

categories: physics.class-ph gr-qc nlin.CD physics.gen-ph


title:
Non-Abelian evolution of electromagnetic waves in a weakly anisotropic
  inhomogeneous medium

abstract:
  A theory of electromagnetic wave propagation in a weakly anisotropic smoothly
inhomogeneous medium is developed, based on the quantum-mechanical
diagonalization procedure applied to Maxwell equations. The equations of motion
for the translational (ray) and intrinsic (polarization) degrees of freedom are
derived ab initio. The ray equations take into account the optical Magnus
effect (spin Hall effect of photons) as well as trajectory variations owing to
the medium anisotropy. Polarization evolution is described by the precession
equation for the Stokes vector. In generic case, the evolution of waves turns
out to be non-Abelian: it is accompanied by mutual conversion of the normal
modes and periodic oscillations of the ray trajectories analogous to electron
zitterbewegung. The general theory is applied to examples of wave evolution in
media with circular and linear birefringence.

categories: physics.optics cond-mat.other physics.plasm-ph quant-ph


title:
Detecting substeps in the rotary motors of FoF1-ATP synthase by Hidden
  Markov Models

abstract:
  FoF1-ATP synthase is the enzyme that provides the 'chemical energy currency'
adenosine triphosphate, ATP, for living cells. The formation of ATP is
accomplished by a stepwise internal rotation of subunits within the enzyme. We
monitor subunit rotation by a single-molecule fluorescence resonance energy
transfer (FRET) approach using two fluorophores specifically attached to the
enzyme. To identify the stepsize of rotary movements by the motors of ATP
synthase we simulated the confocal single-molecule FRET data of freely
diffusing enzymes and developed a step finder algorithm based on 'Hidden Markov
Models' (HMM). The HMM is able to find the proximity factors, P, for a
three-level system and for a five-level system, and to unravel the dwell times
of the simulated rotary movements. To identify the number of hidden states in
the system, a likelihood parameter is calculated for the series of one-state to
eight-state HMMs applied to each set of simulated data. Thereby, the basic
prerequisites for the experimental single-molecule FRET data are defined that
allow for discrimination between a 120 degree stepping mode or a 36 degree
substep rotation mode for the proton-driven Fo motor of ATP synthase.


title:
Electrostatic interaction energies of homogeneous cubic charge
  distributions

abstract:
  The starting point is the problem of finding the interaction energy of two
coinciding homogeneous cubic charge distributions. The brute force method of
subdividing the cube into $N^3$ sub-cubes and doing the sums results in slow
convergence because of the Coulomb singularity. Using symmetry and algebra the
Coulomb singularities can be eliminated. This leads to an accurate numerical
algorithm as well as an interesting exact result relating the desired
interaction energy to three other interaction energies, namely those of cubes
touching each other at a face, at an edge, and at a corner, respectively. As an
application a simple model illustrating Wigner crystallization is presented.


title:
Thermomechanical effects in uniformly aligned dye-doped nematic liquid
  crystals

abstract:
  We show theoretically that thermomechanical effects in dye-doped nematic
liquid crystals when illuminated by laser beams, can become important and lead
to molecular reorientation at intensities substantially lower than that needed
for optical Fr\'eedericksz transition. We propose a 1D model that assumes
homogenous intensity distribution in the plane of the layer and is capable to
describe such a thermally induced threshold lowering. We consider a particular
geometry, with a linearly polarized light incident perpendicularly on a layer
of homeotropically aligned dye-doped nematics.


title:
Pseudo-potential treatment of two aligned dipoles under external
  harmonic confinement

abstract:
  Dipolar Bose and Fermi gases, which are currently being studied extensively
experimentally and theoretically, interact through anisotropic, long-range
potentials. Here, we replace the long-range potential by a zero-range
pseudo-potential that simplifies the theoretical treatment of two dipolar
particles in a harmonic trap. Our zero-range pseudo-potential description
reproduces the energy spectrum of two dipoles interacting through a
shape-dependent potential under external confinement very well, provided that
sufficiently many partial waves are included, and readily leads to a
classification scheme of the energy spectrum in terms of approximate angular
momentum quantum numbers. The results may be directly relevant to the physics
of dipolar gases loaded into optical lattices.


title:
Indirect Dissociative Recombination of LiH$^+$ Molecules Fueled by
  Complex Resonance Manifolds

abstract:
  The LiH$^{+}$ molecule is prototypical of the indirect dissociative
recombination (DR) process, in which a colliding electron destroys the molecule
through Rydberg capture pathways. This Letter develops the first quantitative
test of the Siegert state multichannel quantum defect theory description of
indirect DR for a diatomic molecular ion. The R-matrix approach is adopted to
calculate ab-initio quantum defects, functions of the internuclear distance
that characterize both Rydberg states and the zero-energy collisions of
electrons with LiH$^{+}$ ions. The calculated DR rate coefficient agrees
accurately with recent experimental data (S. Krohn et al, Phys. Rev. Lett. 86,
4005). We identify the doorways to fast indirect DR as complex resonance
manifolds, which couple closed channels having both high and low principal
quantum numbers. This sheds new light on the competition between direct and
indirect DR pathways, and suggests the reason why previous theory
underestimated the DR rate by an order of magnitude.


title:
Estimating Intermittency Exponent in Neutrally Stratified Atmospheric
  Surface Layer Flows: A Robust Framework based on Magnitude Cumulant and
  Surrogate Analyses

abstract:
  This study proposes a novel framework based on magnitude cumulant and
surrogate analyses to reliably detect and estimate the intermittency
coefficient from short-length coarse-resolution turbulent time series.
Intermittency coefficients estimated from a large number of neutrally
stratified atmospheric surface layer turbulent series from various field
campaigns are shown to remarkably concur with well-known laboratory
experimental results. In addition, surrogate-based hypothesis testing
significantly reduces the likelihood of detecting a spurious non-zero
intermittency coefficient from non-intermittent series. The discriminatory
power of the proposed framework is promising for addressing the unresolved
question of how atmospheric stability affects the intermittency properties of
boundary layer turbulence.


title:
How changing physical constants and violation of local position
  invariance may occur?

abstract:
  Light scalar fields very naturally appear in modern cosmological models,
affecting such parameters of Standard Model as electromagnetic fine structure
constant $\alpha$, dimensionless ratios of electron or quark mass to the QCD
scale, $m_{e,q}/\Lambda_{QCD}$. Cosmological variations of these scalar fields
should occur because of drastic changes of matter composition in Universe: the
latest such event is rather recent (redshift $z\sim 0.5$), from matter to dark
energy domination. In a two-brane model (we use as a pedagogical example) these
modifications are due to changing distance to "the second brane", a massive
companion of "our brane". Back from extra dimensions, massive bodies (stars or
galaxies) can also affect physical constants. They have large scalar charge
$Q_d$ proportional to number of particles which produces a Coulomb-like scalar
field $\phi=Q_d/r$. This leads to a variation of the fundamental constants
proportional to the gravitational potential, e.g. $\delta \alpha/ \alpha =
k_\alpha \delta (GM/ r c^2)$. We compare different manifestations of this
effect. The strongest limits $k_\alpha +0.17 k_e= (-3.5\pm 6) * 10^{-7}$ are
obtained from the measurements of dependence of atomic frequencies on the
distance from Sun (the distance varies due to the ellipticity of the Earth's
orbit).

categories: physics.atom-ph astro-ph gr-qc hep-ph nucl-th


title: Scattering of internal waves from small sea bottom inhomogeneities

abstract:
  The problem of scattering of linear internal waves from small compact sea
bottom inhomogeneities is considered from the point of view of mode-to-mode
scattering. A simple formula for modal conversion coefficients, quantifying the
amount of energy that is scattered into the n-th mode from the incident field
m-th mode, is derived. In this formula the representation of inhomogeneities by
their expansions into the Fourier and Fourier-Bessel series with respect to
angular and radial coordinates respectively are used. Results of calculations,
performed in a simple model case, are presented. The obtained formula can be
used for a formulation of the inverse problem, as it was done in the acoustic
case.


title: Einstein's mirror revisited

abstract:
  We describe a simple geometrical derivation of the formula for reflection of
light from a uniformly moving plane mirror directly from the postulates of
special relativity.


title: Variance minimization variational Monte Carlo method

abstract:
  We present a variational Monte Carlo (VMC) method that works equally well for
the ground and the excited states of a quantum system. The method is based on
the minimization of the variance of energy, as opposed to the energy itself in
standard methods. As a test, it is applied to the investigation of the
universal spectrum at the van der Waals length scale for two identical Bose
atoms in a symmetric harmonic trap, with results compared to the basically
exact results obtained from a multiscale quantum-defect theory.


title:
Magnetic field stabilization for high-accuracy mass measurements on
  exotic nuclides

abstract:
  The magnetic-field stability of a mass spectrometer plays a crucial role in
precision mass measurements. In the case of mass determination of short-lived
nuclides with a Penning trap, major causes of instabilities are temperature
fluctuations in the vicinity of the trap and pressure fluctuations in the
liquid helium cryostat of the superconducting magnet. Thus systems for the
temperature and pressure stabilization of the Penning trap mass spectrometer
ISOLTRAP at the ISOLDE facility at CERN have been installed. A reduction of the
fluctuations by at least one order of magnitude downto dT=+/-5mK and
dp=+/-50mtorr has been achieved, which corresponds to a relative frequency
change of 2.7x10^{-9} and 1.5x10^{-10}, respectively. With this stabilization
the frequency determination with the Penning trap only shows a linear temporal
drift over several hours on the 10 ppb level due to the finite resistance of
the superconducting magnet coils.


title:
Synchronization in a neuronal feedback loop through asymmetric temporal
  delays

abstract:
  We consider the effect of asymmetric temporal delays in a system of two
coupled Hopfield neurons. For couplings of opposite signs, a limit cycle
emerges via a supercritical Hopf bifurcation when the sum of the delays reaches
a critical value. We show that the angular frequency of the limit cycle is
independent of an asymmetry in the delays. However, the delay asymmetry
determines the phase difference between the periodic activities of the two
components. Specifically, when the connection with negative coupling has a
delay much larger than the delay for the positive coupling, the system
approaches in-phase synchrony between the two components. Employing variational
perturbation theory (VPT), we achieve an approximate analytical evaluation of
the phase shift, in good agreement with numerical results.


title: Simplest AB-Thermonuclear Space Propulsion and Electric Generator

abstract:
  The author applies, develops and researches mini-sized Micro- AB
Thermonuclear Reactors for space propulsion and space power systems. These
small engines directly convert the high speed charged particles produced in the
thermonuclear reactor into vehicle thrust or vehicle electricity with maximum
efficiency. The simplest AB-thermonuclear propulsion offered allows spaceships
to reach speeds of 20,000 50,000 km/s (1/6 of light speed) for fuel ratio 0.1
and produces a huge amount of useful electric energy. Offered propulsion system
permits flight to any planet of our Solar system in short time and to the
nearest non-Sun stars by E-being or intellectual robots during a single human
life period.
  Key words: AB-propulsion, thermonuclear propulsion, space propulsion,
thermonuclear power system.


title: Novel Technique for Volatile Optical Memory Using Solitons

abstract:
  Recent advances in optics have shown that solitons have a great potential for
upgrading the future optical systems which demand fast and reliable data
transfer. Along side Different architectures have evolved to realize an optical
computer. Due to difference in processing speeds of optical and electronic
devices and usage of opto-electronic converters the efficiency of the optical
computers is affected. In this paper we bring a novel technique for volatile
optical memory using solitons which would be part of realizing an optical
computer. Also the principle of read and write operations in the soliton based
volatile memory systems is shown.


title:
Doped and non-doped organic light-emitting diodes based on a yellow
  carbazole emitter into a blue-emitting matrix

abstract:
  A new carbazole derivative with a 3,3'-bicarbazyl core 6,6'-substituted by
dicyanovinylene groups
(6,6'-bis(1-(2,2'-dicyano)vinyl)-N,N'-dioctyl-3,3'-bicarbazyl; named
(OcCz2CN)2, was synthesized by carbonyl-methylene Knovenagel condensation,
characterized and used as a component of multilayer organic light-emitting
diodes (OLEDs). Due to its -donor-acceptor type structure, (OcCz2CN)2
was found to emit a yellow light at max=590 nm (with the CIE
coordinates x=0.51; y = 0.47) and was used either as a dopant or as an
ultra-thin layer in a blue-emitting matrix of
4,4'-bis(2,2'-diphenylvinyl)-1,1'-biphenyl (DPVBi). DPVBi (OcCz2CN)2-doped
structure exhibited, at doping ratio of 1.5 weight %, a yellowish-green light
with the CIE coordinates (x = 0.31; y = 0.51), an electroluminescence
efficiency EL=1.3 cd/A, an external quantum efficiency ext= 0.4
% and a luminance L= 127 cd/m2 (at 10 mA/cm2) whereas for non-doped devices
utilizing the carbazolic fluorophore as a thin neat layer, a warm white with
CIE coordinates (x = 0.40; y= 0.43), EL= 2.0 cd/A, ext= 0.7 %,
L = 197 cd/m2 (at 10 mA/cm2) and a color rendering index (CRI) of 74, were
obtained. Electroluminescence performances of both the doped and non-doped
devices were compared with those obtained with 5,6,11,12-tetraphenylnaphtacene
(rubrene) taken as a reference of highly efficient yellow emitter.


title: Chiral Structures Under the Standard of Orthogonal Groups

abstract:
  General features of microscopic and macroscopic chiral structures can be
discussed under the standard of orthogonal group theory. Configuration space of
systems, not physical space, is taken into account. This change of perspective
allows to overcome traditional shortcomings related to true and false
chirality, statistical realization of mirror images, classification of objects
as more or less chiral. From this viewpoint, a chiral object is a physical
system whose configurations are described by the O(N) algebra in an abstract
N-dimensional space. A quantum mechanical interpretation is straightforward due
to the fact that combinations of chiral states give rise to parity states which
can be interpreted as energy eigenstates.


title: Investigation of Convective Downburst Hazards to Marine Transportation

abstract:
  Convective downbursts are known to produce potentially hazardous weather
conditions. Currently, severity indices are used to estimate the strength of a
potential downburst, but this information does not readily translate to the
variables affected by downburst events. The effects of downbursts are often
associated with aviation because of rapid changes in wind direction and speed,
but can also be observed in marine conditions. Three recently observed
downburst events have been selected as case studies to evaluate the effects of
the downbursts on the marine environment. The information gathered on these
events includes wind speed, gusts and direction at the surface, air temperature
and pressure, water level, and Wet Microburst Severity Index (WMSI) values.
Correlation between the WMSI values, the maximum wind gust, and the change in
water level is suggested.


title: Self-citation corrections for the Hirsch index

abstract:
  I propose to sharpen the index h, proposed by Hirsch as a useful index to
characterize the scientific output of a researcher, by excluding the
self-citations. Performing a self-experiment and also analyzing two anonymous
data sets, it is shown that self-citations can significantly reduce the $h$
index in contrast to Hirsch's expectations. This result is confirmed by an
analysis of 13 further data sets.


title: Field of the Magnetic Monopole

abstract:
  This paper shows that based upon the Helmholtz decomposition theorem the
field of a stationary magnetic monopole, assuming it exists, cannot be
represented by a vector potential. Persisting to use vector potential in
monopole representation violates fundamentals of mathematics. The importance of
this finding is that the vector potential representation was crucial to the
original prediction of the quantized value for a magnetic charge.


title:
Metallo-Dielectric Multilayer Structure for Lactose Malabsorption
  Diagnosis through H2 Breath Test

abstract:
  A metallo-dielectric multilayer structure is proposed as a novel approach to
the analysis of lactose malabsorption. When lactose intolerance occurs, the
bacterial overgrowth in the intestine causes an increased spontaneous emission
of H2 in the human breath. By monitoring the changes in the optical properties
of a multilayer palladium-polymeric structure, one is able to detect the
patient's disease and the level of lactose malabsorption with high sensitivity
and rapid response.


title: Photographing by means of a diffractive axicon

abstract:
  In this paper we demonstrate that the light diffracted by a simple compact
disc can be used to generate photographic images of a certain kind. Being the
compact disc an axicon that generates a diffraction-free beam, we show that the
focusing position of an image depends of the wavelength of the diffracted
light, what makes possible its use as a spectral filter.


title: Mean flow of turbulent-laminar patterns in plane Couette flow

abstract:
  A turbulent-laminar banded pattern in plane Couette flow is studied
numerically. This pattern is statistically steady, is oriented obliquely to the
streamwise direction, and has a very large wavelength relative to the gap. The
mean flow, averaged in time and in the homogeneous direction, is analysed. The
flow in the quasi-laminar region is not the linear Couette profile, but results
from a non-trivial balance between advection and diffusion. This force balance
yields a first approximation to the relationship between the Reynolds number,
angle, and wavelength of the pattern. Remarkably, the variation of the mean
flow along the pattern wavevector is found to be almost exactly harmonic: the
flow can be represented via only three cross-channel profiles as U(x,y,z) =
U_0(y) + U_c(y) cos(kz) + U_s(y) sin(kz). A model is formulated which relates
the cross-channel profiles of the mean flow and of the Reynolds stress. Regimes
computed for a full range of angle and Reynolds number in a tilted rectangular
periodic computational domain are presented. Observations of regular
turbulent-laminar patterns in other shear flows -- Taylor-Couette,
rotor-stator, and plane Poiseuille -- are compared.


title:
The Ramsey method in high-precision mass spectrometry with Penning
  traps: Experimental results

abstract:
  The highest precision in direct mass measurements is obtained with Penning
trap mass spectrometry. Most experiments use the interconversion of the
magnetron and cyclotron motional modes of the stored ion due to excitation by
external radiofrequency-quadrupole fields. In this work a new excitation
scheme, Ramsey's method of time-separated oscillatory fields, has been
successfully tested. It has been shown to reduce significantly the uncertainty
in the determination of the cyclotron frequency and thus of the ion mass of
interest. The theoretical description of the ion motion excited with Ramsey's
method in a Penning trap and subsequently the calculation of the resonance line
shapes for different excitation times, pulse structures, and detunings of the
quadrupole field has been carried out in a quantum mechanical framework and is
discussed in detail in the preceding article in this journal by M. Kretzschmar.
Here, the new excitation technique has been applied with the ISOLTRAP mass
spectrometer at ISOLDE/CERN for mass measurements on stable as well as
short-lived nuclides. The experimental resonances are in agreement with the
theoretical predictions and a precision gain close to a factor of four was
achieved compared to the use of the conventional excitation technique.


title: The Lorentz-Dirac and Dirac Equations

abstract:
  It is well known that the Classical theory of the electron reached the limits
of its description at time intervals of the order of $10^{-23} secs$, that is
the Compton time. It is widely believed that below these time intervals
Classical Electrodynamics doesn't work and that a Quantum description is
required. Using the Lorentz Dirac and the Dirac equations of the electron, we
point out that in fact there is a convergence of the two descriptions at the
Compton scale.


title:
Turbulence Time Series Data Hole Filling using Karhunen-Loeve and ARIMA
  methods

abstract:
  Measurements of optical turbulence time series data using unattended
instruments over long time intervals inevitably lead to data drop-outs or
degraded signals. We present a comparison of methods using both Principal
Component Analysis, which is also known as the Karhunen--Loeve decomposition,
and ARIMA that seek to correct for these event-induced and mechanically-induced
signal drop-outs and degradations. We report on the quality of the correction
by examining the Intrinsic Mode Functions generated by Empirical Mode
Decomposition. The data studied are optical turbulence parameter time series
from a commercial long path length optical anemometer/scintillometer, measured
over several hundred metres in outdoor environments.


title:
Multiconfiguration Dirac-Hartree-Fock calculations of transition rates
  and lifetimes of the eight lowest excited levels of radium

abstract:
  The multiconfiguration Dirac-Hartree-Fock (MCDHF) model has been employed to
calculate the transition rates between the nine lowest levels of radium. The
dominant rates were then used to evaluate the radiative lifetimes. The decay of
the metastable $ 7s7p ^3 P_0 $ state through 2-photon E1M1 and hyperfine
induced channels is also studied.


title: Albert Einstein: His Annus Mirabilis 1905

abstract:
  Einstein in 1905, his year of miracles, wrote five papers which mark a
watershed between classical physics and modern physics. They dealt with problem
of reality of atoms, theory of special relativity which overthrew Newtonian
conceptions of space and time, and his revolutionary light quantum hypothesis
which together with Planck's work on black body radiation started the quantum
revolution. We put these discoveries in the context of that period and also
indicate their later influence.


title:
Floating Bodies of Equilibrium in 2D, the Tire Track Problem and
  Electrons in a Parabolic Magnetic Field

abstract:
  Explicit solutions of the two-dimensional floating body problem (bodies that
can float in all positions) for relative density different from 1/2 and of the
tire track problem (tire tracks of a bicycle, which do not allow to determine,
which way the bicycle went) are given, which differ from circles. Starting
point is the differential equation given by the author in archive
physics/0205059 and Studies in Appl. Math. 111 (2003) 167-183. The curves are
also trajectories of charges in a perpendicular magnetic field.


title: The time at the subplanckian scale

abstract:
  With the theory of special relativity, time has been linked with space into a
four-dimensional space-time from which a basic question must be asked: can
space be really transformed into time and vice-versa? The response is
affirmative if time has the same structural topological structure as space at
the subplanckian quantum level in such a way that a discrete structural quantum
time constitutes the time part of the space-time internal vacuum of every
elementary particle. It has thus been shown that a quantum time, quantized
algebraically according to a lattice of time quanta, really exists and is
emergent in the sense that time quanta can be transformed into space quanta and
vice-versa. Furthermore,this quantum time, only relevant at the subplanckian
scale, is proved to be in one-to-one correspondence with the absolute and
relative clock times.


title:
A multi-scale approach to the computer-aided detection of
  microcalcification clusters in digital mammograms

abstract:
  A computer-aided detection (CADe) system for the identification of
microcalcification clusters in digital mammograms has been developed. It is
mainly based on the application of wavelet transforms for image filtering and
neural networks for both the feature extraction and the classification
procedures.
  This CADe system is easily adaptable to different databases. We report and
compare the FROC curves obtained on the private database we used for developing
the CADe system and on the publicly available MIAS database. The results
achieved on the two databases show the same trend, thus demonstrating the good
generalization capability of the system.


title:
An automatic system to discriminate malignant from benign massive
  lesions in mammograms

abstract:
  Evaluating the degree of malignancy of a massive lesion on the basis of the
mere visual analysis of the mammogram is a non-trivial task. We developed a
semi-automated system for massive-lesion characterization with the aim to
support the radiological diagnosis. A dataset of 226 masses has been used in
the present analysis. The system performances have been evaluated in terms of
the area under the ROC curve, obtaining A_z=0.80+-0.04.


title: Lung nodule detection in low-dose and high-resolution CT scans

abstract:
  We are developing a computer-aided detection (CAD) system for the
identification of small pulmonary nodules in screening CT scans. The main
modules of our system, i.e. a dot-enhancement filter for nodule candidate
selection and a neural classifier for false positive finding reduction, are
described. The preliminary results obtained on the so-far collected database of
lung CT are discussed.


title: Further de-Entangling Entanglement

abstract:
  A recent general model of entanglement, [5], that goes much beyond the usual
one based on tensor products of vector spaces is further developed here. It is
shown that the usual Cartesian product can be seen as two extreme particular
instances of non-entanglement. Also the recent approach to entanglement in [8]
is incorporated in the general model in [5]. The idea pursued is that
entanglement is by now far too important a phenomenon in Quantum Mechanics, in
order to be left confined to its present exclusive modelling by tensor
products. Once this is realized, it turns out that one can quite easily
de-entangle entanglement from tensor products, and in fact, one can do so in a
large variety of ways. Within such general settings the issue of entanglement
becomes connected with the issue of "System versus Subsystem" in General
Systems Theory, where synthesizing subsystems into a system may often be less
difficult than identifying subsystems in a system.


title:
Analysis, Design and Fabrication of centimeter-wave Dielectric Fresnel
  Zone Plate Lens and reflector

abstract:
  Fresnel lens has a long history in optics. This concept at non-optical
wavelengths is also applicable. In this paper we report design and fabrication
of a half and quarter wave dielectric Fresnel lens made of Plexiglas, and a
Fresnel reflector at 11.1 GHz frequency. We made two lenses and one reflector
at same frequency and compare their gain and radiation pattern to simulated
results. Some methods for better focusing action will be introduced.


title:
Quantum molecular dynamics simulations for the nonmetal-to-metal
  transition in fluid helium

abstract:
  We have performed quantum molecular dynamics simulations for dense helium to
study the nonmetal-to-metal transition at high pressures. We present new
results for the equation of state and the Hugoniot curve in the warm dense
matter region. The optical conductivity is calculated via the Kubo-Greenwood
formula from which the dc conductivity is derived. The nonmetal-to-metal
transition is identified at about 1 g/ccm. We compare with experimental results
as well as with other theoretical approaches, especially with predictions of
chemical models.


title:
On the sensitivity, selectivity, sensory information and optimal size of
  resistive chemical sensors

abstract:
  Information theoretical tools are applied for the study of the sensitivity
and selectivity enhancements of resistive fluctuation-enhanced sensors. General
considerations are given for the upper limit of selectivity enhancement. The
signal-to-noise ratio and information channel capacity of fluctuation-enhanced
chemical sensors is compared to that of classical sensors providing a single
output. The considerations are done at the generic level with a few concrete
examples and include the estimation of scaling relations between the sensor
size, speed of measurements, sampling rate, measurement time, signal power and
noise power.


title:
Theoretical analysis of dynamic chemical imaging with lasers using
  high-order harmonic generation

abstract:
  We report theoretical investigations of the tomographic procedure suggested
by Itatani {\it et al.} [Nature, {\bf 432} 867 (2004)] for reconstructing
highest occupied molecular orbitals (HOMO) using high-order harmonic generation
(HHG). Using the limited range of harmonics from the plateau region, we found
that under the most favorable assumptions, it is still very difficult to obtain
accurate HOMO wavefunction, but the symmetry of the HOMO and the internuclear
separation between the atoms can be accurately extracted, especially when
lasers of longer wavelengths are used to generate the HHG. We also considered
the possible removal or relaxation of the approximations used in the
tomographic method in actual applications. We suggest that for chemical
imaging, in the future it is better to use an iterative method to locate the
positions of atoms in the molecule such that the resulting HHG best fits the
macroscopic HHG data, rather than by the tomographic method.


title: Compensation of eddy-current-induced magnetic field transients in a MOT

abstract:
  The design and implementation of a current driver for the quadrupole coil of
a magneto-optical trap are presented. The control and the power stages of the
driver, both based on a push-pull configuration with high-speed transistors,
are separated, allowing for a protection of the control electronics. Moreover,
the coil current can be set by an analog voltage, a feature that makes possible
both fast and adiabatic switching of the quadrupole magnetic field. In order to
compensate magnetic field transients induced by eddy currents, the driver
allows a quick reversal of the quadrupole coil current providing in such a way
the required magnetic flux compensation. From a fit to the measured magnetic
field transients, we have extracted the decay constants which confirm the
efficiency of the compensation. Furthermore, we measured the influence of eddy
currents on a sample of cold caesium atoms, testing at the same time the
ultimate performance of the driver for our applications. The results show that
the implemented electronic circuit is able to reduce substantially the
transient effects with switching times of the magnetic field below 100
microseconds.


title:
Experimental Observation of Modulation Instability and Optical Spatial
  Soliton Arrays in Soft Condensed Matter

abstract:
  In this Letter we report observations of optically induced self-organization
of colloidal arrays in the presence of un-patterned counter-propagating
evanescent waves. The colloidal arrays formed along the laser propagation-axis
are shown to be linked to the break-up of the incident field into optical
spatial solitons, the lateral spacing of the arrays being related to modulation
instability of the soft condensed matter system.


title: Variational approach for the quantum Zakharov system

abstract:
  The quantum Zakharov system is described in terms of a Lagrangian formalism.
A time-dependent Gaussian trial function approach for the envelope electric
field and the low-frequency part of the density fluctuation leads to a coupled,
nonlinear system of ordinary differential equations. In the semiclassic case,
linear stability analysis of this dynamical system shows a destabilizing r\^ole
played by quantum effects. Arbitrary value of the quantum effects are also
considered, yielding the ultimate destruction of the localized, Gaussian trial
solution. Numerical simulations are shown both for the semiclassic and the full
quantum cases.


title:
Green modified function of the equation of the internal gravity waves in
  the stratum of the stratified medium with constant average flow

abstract:
  In the present paper construction of the modified function of Green equation
for internal gravity waves in the stratum of the stratified medium at presence
of constant average flows is considered, properties of the corresponding
spectral problems, the modified eigenfunctions and eigenvalues are
investigated. Usage of the modified function of Green equation can give in some
physically interesting events more friendly representations of the solutions
for the fields of the internal gravity waves, including the wave fields
disturbed by the non-local disturbing bodies.


title: Proximity Networks and Epidemics

abstract:
  Disease spread in most biological populations requires the proximity of
agents. In populations where the individuals have spatial mobility, the contact
graph is generated by the "collision dynamics" of the agents, and thus the
evolution of epidemics couples directly to the spatial dynamics of the
population. We first briefly review the properties and the methodology of an
agent-based simulation (EPISIMS) to model disease spread in realistic urban
dynamic contact networks. Using the data generated by this simulation, we
introduce the notion of dynamic proximity networks which takes into account the
relevant time scales for disease spread: contact duration, infectivity period
and rate of contact creation. This approach promises to be a good candidate for
a unified treatment of epidemic types that are driven by agent collision
dynamics. In particular, using a simple model, we show that it can can account
for the observed qualitative differences between the degree distributions of
contact graphs of diseases with short infectivity period (such as
air-transmitted diseases) or long infectivity periods (such as HIV).


title: Lorentz covariance of the canonical perfect lens

abstract:
  The canonical perfect lens--comprising three slabs, each made of a linear,
homogeneous, bianisotropic material with orthorhombic symmetry--is Lorentz
covariant.


title: Beam-plasma dielectric tensor with Mathematica

abstract:
  We present a \emph{Mathematica} notebook allowing for the symbolic
calculation of the $3\times3$ dielectric tensor of a electron-beam plasma
system in the fluid approximation. Calculation is detailed for a cold
relativistic electron beam entering a cold magnetized plasma, and for
arbitrarily oriented wave vectors. We show how one can elaborate on this
example to account for temperatures, arbitrarily oriented magnetic field or a
different kind of plasma.


title:
The structure of the Sun and the planets of the solar system from the
  viewpoint of mechanics of the inertless mass I

abstract:
  In this monograph (written in 1973-1974) the author uses the theory of
mechanics of the inertless mass to investigate the structure of heavenly bodies
of the solar system. The structure of the Sun and planets is the sole reason of
the character of their axial rotation, presence or absence of satellites and
atmospheres. This structure is one of the main climatic factors for each planet
and Sun. It determines the climate and its possible changes. Understanding
these processes is very important for determining perspectives of the evolution
of the Sun and the planets, including the Earth. This monograph was divided
into two parts by editor in 2007. Since author has developed some theoretical
positions of "Mechanics of liquids and gas, or mechanics of the inertless mass"
(1971), the first Part contains these changes. The Part II contains the
investigation that gives us new results and new meaning of the stored
information about the Sun and the planets of the solar system. This monograph
is addressed to specialists in the field of theoretical and practical
hydrodynamics and adjacent sciences. It will be useful for astronomers,
meteorologists and geologists.


title:
The structure of the Sun and the planets of the solar system from the
  viewpoint of mechanics of the inertless mass II

abstract:
  The second part of the monograph contains the investigation of the structure
of the Sun and planets of the solar system. This monograph is addressed to
specialists in the field of theoretical and practical hydrodynamics and
adjacent sciences. It will be useful for astronomers, meteorologists and
geologists.


title: Negative refraction of a three-dimensional metallic photonic crystal

abstract:
  A metamaterial with a negative effective index of refraction is made from a
three-dimensional hexagonal lattice photonic crystal with a metallic basis
embedded in foam. It has been simulated with Ansoft HFSSTM in a frequency range
from 7.0 to 12.0 GHz. Simulated results tested experimentally and negative
refraction verified in some frequencies. Experimental results are in excellent
agreement with simulations.


title: Measuring spike train synchrony

abstract:
  Estimating the degree of synchrony or reliability between two or more spike
trains is a frequent task in both experimental and computational neuroscience.
In recent years, many different methods have been proposed that typically
compare the timing of spikes on a certain time scale to be fixed beforehand.
Here, we propose the ISI-distance, a simple complementary approach that
extracts information from the interspike intervals by evaluating the ratio of
the instantaneous frequencies. The method is parameter free, time scale
independent and easy to visualize as illustrated by an application to real
neuronal spike trains obtained in vitro from rat slices. In a comparison with
existing approaches on spike trains extracted from a simulated Hindemarsh-Rose
network, the ISI-distance performs as well as the best time-scale-optimized
measure based on spike timing.


title: Gray spatial solitons in nonlocal nonlinear media

abstract:
  We study gray solitons in nonlocal nonlinear media and show that they are
stable and can form bound states. We reveal that gray soliton velocity depends
on the nonlocality degree, and that it can be drastically reduced in highly
nonlocal media. This is in contrast to the case of local media, where the
maximal velocity is dictated solely by the asymptotic soliton amplitude.


title:
Laser-trapping of Ra-225 and Ra-226 with repumping by room temperature
  blackbody radiation

abstract:
  We have demonstrated Zeeman slowing and capture of neutral Ra-225 and Ra-226
atoms in a magneto-optical trap (MOT). The intercombination transition 1S0-3P1
is the only quasi-cycling transition in radium and was used for laser-cooling
and trapping. Repumping along the 3D1-1P1 transition extended the lifetime of
the trap from milliseconds to seconds. Room-temperature blackbody radiation was
demonstrated to provide repumping from the metastable 3P0 level. We measured
the isotope shift and hyperfine splittings on the 3D1-1P1 transition with the
laser-cooled atoms, and set a limit on the lifetime of the 3D1 level based on
the measured blackbody repumping rate. Laser-cooled and trapped radium is an
attractive system for studying fundamental symmetries.


title: Martingales, Detrending Data, and the Efficient Market Hypothesis

abstract:
  We discuss martingales, detrending data, and the efficient market hypothesis
for stochastic processes x(t) with arbitrary diffusion coefficients D(x,t).
Beginning with x-independent drift coefficients R(t) we show that Martingale
stochastic processes generate uncorrelated, generally nonstationary increments.
Generally, a test for a martingale is therefore a test for uncorrelated
increments. A detrended process with an x- dependent drift coefficient is
generally not a martingale, and so we extend our analysis to include the class
of (x,t)-dependent drift coefficients of interest in finance. We explain why
martingales look Markovian at the level of both simple averages and 2-point
correlations. And while a Markovian market has no memory to exploit and
presumably cannot be beaten systematically, it has never been shown that
martingale memory cannot be exploited in 3-point or higher correlations to beat
the market. We generalize our Markov scaling solutions presented earlier, and
also generalize the martingale formulation of the efficient market hypothesis
(EMH) to include (x,t)-dependent drift in log returns. We also use the analysis
of this paper to correct a misstatement of the fair game condition in terms of
serial correlations in Fama's paper on the EMH.


title:
Absorbing boundaries in numerical solutions of the time-dependent
  Schr\"odinger equation on a grid using exterior complex scaling

abstract:
  We study the suppression of reflections in the numerical simulation of the
time-dependent Schr\"odinger equation for strong-field problems on a grid using
exterior complex scaling (ECS) as absorbing boundary condition. It is shown
that the ECS method can be applied in both the length and the velocity gauge as
long as appropriate restrictions are applied in the ECS transformation of the
electron-field coupling. It is found that the ECS method improves the
suppression of reflection as compared to the conventional masking technique in
typical simulations of atoms exposed to an intense laser pulse. Finally, we
demonstrate the advantage of the ECS technique to avoid unphysical artifacts in
the evaluation of high harmonic spectra.


title:
Relative incapacitation contributions of pressure wave and wound channel
  in the Marshall and Sanow data set

abstract:
  The Marshall and Sanow data set is the largest and most comprehensive data
set available quantifying handgun bullet effectiveness in humans. This article
presents an empirical model for relative incapacitation probability in humans
hit in the thoracic cavity by handgun bullets. The model is constructed by
employing the hypothesis that the wound channel and ballistic pressure wave
effects each have an associated independent probability of incapacitation.
Combining models for these two independent probabilities using the elementary
rules of probability and performing a least-squares fit to the Marshall and
Sanow data provides an empirical model with only two adjustable parameters for
modeling bullet effectiveness with a standard error of 5.6% and a correlation
coefficient R = 0.939. This supports the hypothesis that wound channel and
pressure wave effects are independent (within the experimental error), and it
also allows assignment of the relative contribution of each effect for a given
handgun load. This model also gives the expected limiting behavior in the cases
of very small and very large variables (wound channel and pressure wave), as
well as for incapacitation by rifle and shotgun projectiles.


title:
Ballistic pressure wave contributions to rapid incapacitation in the
  Strasbourg goat tests

abstract:
  This article presents empirical models for the relationship between peak
ballistic pressure wave magnitude and incapacitation times in the Strasbourg
goat test data. Using a model with the expected limiting behavior at large and
small pressure wave magnitudes, the average incapacitation times are highly
correlated (R = 0.91) with peak pressure wave magnitude. The cumulative
incapacitation probability as a function of time reveals both fast (t < 5 s)
and slow (t > 5 s) incapacitation mechanisms. The fast incapacitation mechanism
can be accurately modeled as a function of peak pressure wave magnitude. The
slow incapacitation mechanism is presumably due to blood loss via damaged
vascular tissue.


title:
Review of criticisms of ballistic pressure wave experiments, the
  Strasbourg goat tests, and the Marshall and Sanow data

abstract:
  This article reviews published criticisms of several ballistic pressure wave
experiments authored by Suneson et al., the Marshall and Sanow "one shot stop"
data set, and the Strasbourg goat tests. These published criticisms contain
numerous logical and rhetorical fallacies, are generally exaggerated, and fail
to convincingly support the overly broad conclusions they contain.


title: Water adsorption and dissociation on BeO (001) and (100) surfaces

abstract:
  Plateaus in water adsorption isotherms on hydroxylated BeO surfaces suggest
significant differences between the hydroxylated (100) and (001) surface
structures and reactivities. Density functional theory structures and energies
clarify these differences. Using relaxed surface energies, a Wulff construction
yields a prism crystal shape exposing long (100) sides and much smaller (001)
faces. This is consistent with the BeO prisms observed when beryllium metal is
oxidized. A water oxygen atom binds to a single surface beryllium ion in the
preferred adsorption geometry on either surface. The water oxygen/beryllium
bonding is stronger on the surface with greater beryllium atom exposure, namely
the less-stable (001) surface. Water/beryllium coordination facilitates water
dissociation. On the (001) surface, the dissociation products are a hydroxide
bridging two beryllium ions and a metal coordinated hydride with some surface
charge depletion. On the (100) surface, water dissociates into a hydroxide
ligating a Be atom and a proton coordinated to a surface oxygen but the lowest
energy water state on the (100) surface is the undissociated metal-coordinated
water. The (100) fully hydroxylated surface structure has a hydrogen bonding
network which facilitates rapid proton shuffling within the network. The
corresponding (001) hydroxylated surface is fairly open and lacks internal
hydrogen bonding. This supports previous experimental interpretations of the
step in water adsorption isotherms. Further, when the (100) surface is heated
to 1000 K, hydroxides and protons associate and water desorbs. The more open
(001) hydroxylated surface is stable at 1000 K. This is consistent with the
experimental disappearance of the isotherm step when heating to 973 K.


title:
Silicon Sensors implemented on p-type substrates for high radiation
  resistance applications

abstract:
  Silicon based micropattern detectors are essential elements of modern high
energy physics experiments. Cost effectiveness and high radiation resistance
are two important requirements for technologies to be used in inner tracking
devices. Processes based on p-type substrates have very strong appeal for these
applications. Recent results and prototype efforts under way are reviewed.


title: Improvement of the Kalman Filter Fit of the ZEUS experiment

abstract:
  At the center of the ZEUS detector situated on the collider HERA at DESY in
Hamburg, a Micro Vertex Detector has been installed in 2000/01. Situated close
to the beam line, this subdetector is designed to measure precisely the tracks
near the interaction point (the vertex). A package called KFFIT is designated
to perform the track fit of the Micro Vertex Detector hits using a Kalman
Filter. This paper is a report of all improvements done in this package. After
a brief description of the algorithm, the improvements of KFFIT will be
presented comparing the last version (v10 released in December 2006) to the
initial one (v1 released in December 2005 (=v2005a.1)).


title: Experimental single-impulse magnetic focusing of launched cold atoms

abstract:
  Single-impulse three-dimensional magnetic focusing of vertically launched
cold atoms has been observed. Four different configurations of the lens were
used to vary the relative radial and axial focusing properties. Compact focused
clouds of 85Rb were seen for all four configurations. It is shown that an
atom-optical ray matrix approach for describing the lensing action is
insufficient. Numerical simulation using a full approximation to the lens's
magnetic field shows very good agreement with the radial focusing properties of
the lens. However, the axial (vertical direction) focusing properties are less
well described and the reasons for this are discussed.


title:
Construction and Expected Performance of the Hadron Blind Detector for
  the PHENIX Experiment at RHIC

abstract:
  A new Hadron Blind Detector (HBD) for electron identification in high density
hadron environment has been installed in the PHENIX detector at RHIC in the
fall of 2006. The HBD will identify low momentum electron-positron pairs to
reduce the combinatorial background in the $e^{+}e^{-}$ mass spectrum, mainly
in the low-mass region below 1 GeV/c$^{2}$. The HBD is a windowless
proximity-focusing Cherenkov detector with a radiator length of 50 cm, a CsI
photocathode and three layers of Gas Electron Multipliers (GEM). The HBD uses
pure CF$_{4}$ as a radiator and a detector gas. Construction details and the
expected performance of the detector are described.


title:
Intermittency and universality in a Lagrangian model of velocity
  gradients in three-dimensional turbulence

abstract:
  The universality of intermittency in hydrodynamic turbulence is considered
based on a recent model for the velocity gradient tensor evolution. Three
possible versions of the model are investigated differing in the assumed
correlation time-scale and forcing strength. Numerical tests show that the same
(universal) anomalous relative scaling exponents are obtained for the three
model variants. It is also found that transverse velocity gradients are more
intermittent than longitudinal ones, whereas dissipation and enstrophy scale
with the same exponents. The results are consistent with the universality of
intermittency and relative scaling exponents, and suggest that these are
dictated by the self-stretching terms that are the same in each variant of the
model.


title: A Monolithic Time Stretcher for Precision Time Recording

abstract:
  Identifying light mesons which contain only up/down quarks (pions) from those
containing a strange quark (kaons) over the typical meter length scales of a
particle physics detector requires instrumentation capable of measuring flight
times with a resolution on the order of 20ps. In the last few years a large
number of inexpensive, multi-channel Time-to-Digital Converter (TDC) chips have
become available. These devices typically have timing resolution performance in
the hundreds of ps regime. A technique is presented that is a monolithic
version of ``time stretcher'' solution adopted for the Belle Time-Of-Flight
system to address this gap between resolution need and intrinsic multi-hit TDC
performance.


title:
Icosahedral quasicrystals for visible wavelengths by optical
  interference holography

abstract:
  Quasicrystals, realized in metal alloys, are a class of lattices exhibiting
symmetries that fall outside the usual classification for periodic crystals.
They do not have translational symmetry and yet the lattice points are well
ordered. Furthermore, they exhibit higher rotational symmetry than periodic
crystals. Because of the higher symmetry (more spherical), they are more
optimal than periodic crystals in achieving complete photonic bandgaps in a new
class of materials called photonic crystals in which the propagation of light
in certain frequency ranges is forbidden. The potential of quasicrystals has
been demonstrated in two dimensions for the infrared range and, recently, in
three-dimensional icosahedral quasicrystals fabricated using a stereo
lithography method for the microwave range. Here, we report the fabrication and
optical characterization of icosahedral quasicrystals using a holographic
lithography method for the visible range. The icosahedral pattern, generated
using a novel 7-beam optical interference holography, is recorded on
photoresists and holographic plates. Electron micrographs of the photoresist
samples show clearly the symmetry of the icosahedral quasicrytals in the
submicron range, while the holographic plate samples exhibit bandgaps in the
angular-dependent transmission spectra in the visible range. Calculations of
the bandgaps due to reflection planes inside the icosahedral quasicrystal show
good agreement with the experimental results.


title:
Can a charged ring levitate a neutral, polarizable object? Can
  Earnshaw's Theorem be extended to such objects?

abstract:
  Stable electrostatic levitation and trapping of a neutral, polarizable object
by a charged ring is shown to be theoretically impossible. Earnshaw's Theorem
precludes the existence of such a stable, neutral particle trap.


title:
The motion of solids in liquids and gases from the viewpoint of
  mechanics of the inertless mass

abstract:
  This monograph (written in 1974) is the last part of the author's study in
the field of theoretical and practical mechanics of the inertless mass (or
mechanics of continuous medium). The investigation enriches the theory and
provides complete understanding the essence of such wide-spread phenomena as
streamlining, lifting power, wave resistance, and explains particular features
of the resistance for a solid moving with a supersonic velocity. A new
principle is presented for calculating the screw propeller which does not make
a breaker behind the ships. This monograph is addressed to specialists in the
field of theoretical and practical hydrodynamics and adjacent sciences. It will
be useful for engineers.


title:
Some new parallel flows due to Lorentz forces in electrically conducting
  fluids

abstract:
  We investigate the fully developed flow between two parallel plates and the
film flow over a plate in an electrically conducting fluid under the action of
a parallel Lorentz force. Exact analytical solutions are derived for velocity,
flow rate and wall shear stress at the plates. The velocity results are
presented in figures. All these flows are new and are presented for the first
time in the literature.


title:
Constructional details for A simple atmospheric electrical instrument
  for educational use

abstract:
  Electricity in the atmosphere provides an ideal topic for educational
outreach in environmental science. To support this objective, a simple
instrument to measure real atmospheric electrical parameters has been developed
and its performance evaluated. This project compliments educational activities
undertaken by the Coupling of Atmospheric Layers (CAL) European research
collaboration. The new instrument is inexpensive to construct and simple to
operate, readily allowing it to be used in schools as well as at the
undergraduate University level. It is suited to students at a variety of
different educational levels, as the results can be analysed with different
levels of sophistication. Students can make measurements of the fair weather
electric field and current density, thereby gaining an understanding of the
electrical nature of the atmosphere. This work was stimulated by the centenary
of the 1906 paper in which C.T.R. Wilson described a new apparatus to measure
the electric field and conduction current density. Measurements using
instruments based on the same principles continued regularly in the UK until
1979. The instrument proposed is based on the same physical principles as
C.T.R. Wilson's 1906 instrument. The constructional details of the instrument
are provided here.


title: The BRAHMS ring imaging Cherenkov detector

abstract:
  A Ring Imaging \v{C}erenkov detector built for the BRAHMS experiment at the
Brookhaven RHIC is described. This detector has a high index of refraction gas
radiator. \v{C}erenkov light is focused on a photo-multiplier based photon
detector with a large spherical mirror. The combination of momentum and ring
radius measurement provides particle identification from 2.5 GeV/c up to 35
GeV/c for pions and kaons and well above 40 GeV/c for protons during runs that
had the radiator index of refraction set at $n-1=1700 \times 10^{-6}$.


title: What is special about water as a matrix of life?

abstract:
  Water offers a large temperature domain of stable liquid, and the
characteristic hydrophobic effects are first a consequence of the temperature
insensitivity of equation-of-state features of the aqueous medium, compared to
other liquids. On this basis, the known aqueous media and conditions offer low
risk compared to alternatives as a matrix to which familiar molecular
biological structures and processes have adapted. The current molecular-scale
understanding of hydrophobic hydration is not conformant in detail with a
standard structural entropy rationalization. That classic pictorial explanation
may serve as a mnemonic, but isn't necessary. A more defensible view is that
peculiar hydrophobic effects can be comprehended by examination of engineering
parameters characterizing liquid water.


title: The Great Season Climatic Oscillation

abstract:
  The variations of water density and thermal conductivity of the oceans cold
region waters according to their salinity lead to suggest an hypothesis of an
oscillating climate between two extreme positions: a maximum of hot
temperatures and a minimum of cold ones. It will be shown that the distance
separating the surface hot streams from the depth cold ones oscillate between
two limit values linked to the optimal melting and regeneration glaciers. The
melting and regeneration glaciers cycle leads to the Great Saison Climatic
Oscillations phenomenon necessary to the regeneration of fresh water resources
of our planet.


title: Understanding Student Pathways in Context-rich Problems

abstract:
  In this paper we investigate the extent to which students' problem-solving
behaviors change as a result of working on multi-faceted, context-rich
problems. During the semester, groups of two to three students work on several
problems that require more than one concept and hence cannot be readily solved
with simple plug-and-chug strategies. The problems are presented to students in
a data-rich, online problem-solving environment that tracks which information
items are selected by students as they attempt to solve the problem. The
students also complete a variety of tasks, such as entering their qualitative
analysis into an online form. Students are not constrained to complete these
tasks in any order. As they gain more experience in solving multifaceted
physics problems, the student groups show some progression towards expert-like
behavior: earlier qualitative analysis and more selective requests for
information. However, there is room for more improvement as approximately half
of the groups still complete the qualitative analysis task towards the end of
the solution instead of earlier when it would be most useful to their work.


title:
A 3D biomechanical vocal tract model to study speech production control:
  How to take into account the gravity?

abstract:
  This paper presents a modeling study of the way speech motor control can deal
with gravity to achieve steady-state tongue positions. It is based on
simulations carried out with the 3D biomechanical tongue model developed at
ICP, which is now controlled with the Lambda model (Equilibrium-Point
Hypothesis). The influence of short-delay orosensory feedback on posture
stability is assessed by testing different muscle force/muscle length
relationships (Invariant Characteristics). Muscle activation patterns necessary
to maintain the tongue in a schwa position are proposed, and the relations of
head position, tongue shape and muscle activations are analyzed.


title:
Thermodynamics of a Dust Universe, Energy density, Temperature, Pressure
  and Entropy for Cosmic Microwave Background

abstract:
  This paper continues the building of the cosmological theory that was
introduced in two earlier papers under the title A Dust Universe Solution to
the Dark Energy Problem. The model introduced in this theory has existence
before time zero so that it is not necessary to interpret it as of big-bang
origin. The location of the Cosmic Microwave Background, within the theoretical
structure gives a closing of the fundamentals of the model in terms of the
definitions of Temperature, Entropy and other Thermodynamic aspects. Thus
opening up a research tool in cosmology in exact agreement with experiment that
can compete with the so-called Standard Big Bang Model as a
mathematical-physical description of our universe based rigorously on
Einstein's general relativity. It is suggested that the singularity at time
zero involves a population inversion in the statistical mechanics sense and so
justifies the use of negative temperature for the CMB at negative times. This
also has the satisfactory consequence that the Universe's evolution involves
entropy steadily increasing over all time from minus infinity through the
singularity to plus infinity.An appendix with its own abstract contains an
alternative simple classical physics derivation of this model and an extended
discussion about how it can be used in the astrophysical context of galactic
motions. A cosmological Schroedinger equation of great generality is derived
which unites cosmology and the quantum description of cosmological objects


title:
Weakly nonlinear waves in magnetized plasma with a slightly
  non-Maxwellian electron distribution. Part 2. Stability of cnoidal waves

abstract:
  We determine the growth rate of linear instabilities resulting from
long-wavelength transverse perturbations applied to periodic nonlinear wave
solutions to the Schamel-Korteweg-de Vries-Zakharov-Kuznetsov (SKdVZK) equation
which governs weakly nonlinear waves in a strongly magnetized cold-ion plasma
whose electron distribution is given by two Maxwellians at slightly different
temperatures. To obtain the growth rate it is necessary to evaluate non-trivial
integrals whose number is kept to minimum by using recursion relations. It is
shown that a key instance of one such relation cannot be used for classes of
solution whose minimum value is zero, and an additional integral must be
evaluated explicitly instead. The SKdVZK equation contains two nonlinear terms
whose ratio $b$ increases as the electron distribution becomes increasingly
flat-topped. As $b$ and hence the deviation from electron isothermality
increases, it is found that for cnoidal wave solutions that travel faster than
long-wavelength linear waves, there is a more pronounced variation of the
growth rate with the angle $\theta$ at which the perturbation is applied.
Solutions whose minimum value is zero and travel slower than long-wavelength
linear waves are found, at first order, to be stable to perpendicular
perturbations and have a relatively narrow range of $\theta$ for which the
first-order growth rate is not zero.


title: Self-consistent Langmuir waves in resonantly driven thermal plasmas

abstract:
  The longitudinal dynamics of a resonantly driven Langmuir wave are analyzed
in the limit that the growth of the electrostatic wave is slow compared to the
bounce frequency. Using simple physical arguments, the nonlinear distribution
function is shown to be nearly gaussian in the canonical particle action, with
a slowly evolving mean and fixed variance. Self-consistency with the
electrostatic potential provide the basic properties of the nonlinear
distribution function including a frequency shift that agrees well with driven,
electrostatic particle simulations. This extends earlier work on nonlinear
Langmuir waves by Morales and O'Neil [G. J. Morales and T. M. O'Neil, Phys.
Rev. Lett. 28, 417 (1972)], and could form the basis of a reduced kinetic
treatment of Raman backscatter in a plasma.


title:
A fundamental scale of mass for black holes from the cosmological
  constant

abstract:
  The existence of a positive cosmological constant leads naturally to two
fundamental scales of length, being the De Sitter horizon and the radius of the
cell associated with a holographic degree of freedom. Associated with each of
those scales of length are a macroscopic gravitational mass and a microscopic
quantum mechanical mass. Three of those four fundamental masses have been
discussed in the literature, and this present work identifies the physical
significance of the remaining mass, being the gravitational mass associated
with the holographic length. That mass, which is of the order 10^{12}kg and
inversely proportional to the sixth root of the cosmological constant,
represents the mass of the black hole whose evaporation time is equal to the
fundamental cosmic time, which is of the order the current age of the universe.
It also represents the minimum mass of a black hole that is capable of
accreting a particle whose Compton wavelength is equal to the fundamental
holographic length, which is of the order the Compton wavelength of the
nucleon.


title: The rich-club phenomenon across complex network hierarchies

abstract:
  The so-called rich-club phenomenon in a complex network is characterized when
nodes of higher degree (hubs) are better connected among themselves than are
nodes with smaller degree. The presence of the rich-club phenomenon may be an
indicator of several interesting high-level network properties, such as
tolerance to hub failures. Here we investigate the existence of the rich-club
phenomenon across the hierarchical degrees of a number of real-world networks.
Our simulations reveal that the phenomenon may appear in some hierarchies but
not in others and, moreover, that it may appear and disappear as we move across
hierarchies. This reveals the interesting possibility of non-monotonic behavior
of the phenomenon; the possible implications of our findings are discussed.


title: Detector Time Offset and Off-line Calibration in EAS Experiments

abstract:
  In Extensive Air Shower (EAS) experiments, the primary direction is
reconstructed by the space-time pattern of secondary particles. Thus the
equalization of the transit time of signals coming from different parts of the
detector is crucial in order to get the best angular resolution and pointing
accuracy allowed by the detector. In this paper an off-line calibration method
is proposed and studied by means of proper simulations. It allows to calibrate
the array repeatedly just using the collected data without disturbing the
standard acquisition. The calibration method is based on the definition of a
Characteristic Plane introduced to analyze the effects of the time systematic
offsets, such as the quasi-sinusoidal modulation on azimuth angle distribution.
This calibration procedure works also when a pre-modulation on the primary
azimuthal distribution is present.


title: Dynamics and Infrared Spectroscopy of the Protonated Water Dimer

abstract:
  The dynamics and infrared absorption spectrum of the protonated water dimer
are reported by full quantum simulation. Strong couplings between the
spectroscopically active proton-transfer motion and low-frequency,
large-amplitude torsional modes are clearly identified and their role in the
cluster dynamics is explained. These couplings are responsible for the
characteristic doublet-peak around 1000 cm-1, which was not understood and
subject of debate. This spectral feature is reproduced, assigned and explained.