title: Inviscid coalescence of drops

abstract:
  We study the coalescence of two drops of an ideal fluid driven by surface
tension. The velocity of approach is taken to be zero and the dynamical effect
of the outer fluid (usually air) is neglected. Our approximation is expected to
be valid on scales larger than $\ell_{\nu} = \rho\nu^2/\sigma$, which is $10
nm$ for water. Using a high-precision boundary integral method, we show that
the walls of the thin retracting sheet of air between the drops reconnect in
finite time to form a toroidal enclosure. After the initial reconnection,
retraction starts again, leading to a rapid sequence of enclosures. Averaging
over the discrete events, we find the minimum radius of the liquid bridge
connecting the two drops to scale like $r_b \propto t^{1/2}$.


title:
Fokker-Planck Equation for Boltzmann-type and Active Particles: transfer
  probability approach

abstract:
  Fokker-Planck equation with the velocity-dependent coefficients is considered
for various isotropic systems on the basis of probability transition (PT)
approach. This method provides the self-consistent and universal description of
friction and diffusion for Brownian particles. Renormalization of the friction
coefficient is shown to occur for two dimensional (2-D) and three dimensional
(3-D) cases, due to the tensorial character of diffusion. The specific forms of
PT are calculated for the Boltzmann-type of collisions and for the
absorption-type of collisions (the later are typical for dusty plasmas and some
other systems). Validity of the Einstein's relation for the Boltzmann-type
collisions is analyzed for the velocity-dependent friction and diffusion
coefficients. For the Boltzmann-type collisions in the region of very high
grain velocity as well as it is always for non-Boltzmann collisions, such as,
e.g., absorption collisions, the Einstein relation is violated, although some
other relations (determined by the structure of PT) can exist. The generalized
friction force is investigated in dusty plasma in the framework of the PT
approach. The relation between this force, negative collecting friction force
and scattering and collecting drag forces is established.+AFwAXA- The concept
of probability transition is used to describe motion of active particles in an
ambient medium. On basis of the physical arguments the PT for a simple model of
the active particle is constructed and the coefficients of the relevant
Fokker-Planck equation are found. The stationary solution of this equation is
typical for the simplest self-organized molecular machines.+AFwAXA- PACS
number(s): 52.27.Lw, 52.20.Hv, 52.25.Fi, 82.70.-y


title:
Preliminary Study of the Feasibility of a Non Crystalline Positron
  Emission Tomography Using a Suspension of Superheated Superconducting Grains
  (SSG) in High Density Dielectric Matrix (HDDM) as Detector

abstract:
  Suspensions of superheated superconducting grains are a detecting composite
material. Each grain in the supension is a microcalorimeter with an energy
threshold defined by its equatorial magnetic field for a given temperature. The
higher the matrix density, the larger the gamma stopping power. For several
years, cylindrical cells of such suspensions about 2 cm long and 0.4 mm in
diameter can be read out in real time. As a result, using two independent
cells, one can record a time coincidence between them. This could be
potentially very useful for positron cameras where two diametrically opposite
cells are simultaneously knocked by 511 keV gammas. This paper, based on the
state of art in SSG in high density matrix, discusses such a feasibility.


title:
Molecular Alignment and Orientation: From Laser-Induced Mechanisms to
  Optimal Control

abstract:
  Genetic algorithms, as implemented in optimal control strategies, are
currently successfully exploited in a wide range of problems in molecular
physics. In this context, laser control of molecular alignment and orientation
remains a very promising issue with challenging applications extending from
chemical reactivity to nanoscale design. We emphasize the complementarity
between basic quantum mechanisms monitoring alignment/orientation processes and
optimal control scenarios. More explicitly, if on one hand we can help the
optimal control scheme to take advantage of such mechanisms by appropriately
building the targets and delineating the parameter sampling space, on the other
hand we expect to learn, from optimal control results, some robust and
physically sound dynamical mechanisms. We present basic mechanisms for
alignment and orientation, such as pendular states accommodated by the
molecule-plus-field effective potential and the "kick" mechanism obtained by a
sudden excitation. Very interestingly, an optimal control scheme for
orientation, based on genetic algorithms, also leads to a sudden pulsed field
bearing the characteristic features of the kick mechanism. Optimal pulse
shaping for very efficient and long-lasting orientation, together with
robustness with respect to temperature effects, are among our future prospects.


title:
Multiresolution analysis in statistical mechanics. I. Using wavelets to
  calculate thermodynamic properties

abstract:
  The wavelet transform, a family of orthonormal bases, is introduced as a
technique for performing multiresolution analysis in statistical mechanics. The
wavelet transform is a hierarchical technique designed to separate data sets
into sets representing local averages and local differences. Although
one-to-one transformations of data sets are possible, the advantage of the
wavelet transform is as an approximation scheme for the efficient calculation
of thermodynamic and ensemble properties. Even under the most drastic of
approximations, the resulting errors in the values obtained for average
absolute magnetization, free energy, and heat capacity are on the order of 10%,
with a corresponding computational efficiency gain of two orders of magnitude
for a system such as a $4\times 4$ Ising lattice. In addition, the errors in
the results tend toward zero in the neighborhood of fixed points, as determined
by renormalization group theory.


title:
Comment on ``Dynamical Foundations of Nonextensive Statistical
  Mechanics"

abstract:
  In a recent letter, Christian Beck described a theoretical link between a
family of stochastic differential equations and the probability density
functions (PDF) derived from the formalism of nonextensive statistical
mechanics. He applied the theory to explain experimentally measured PDFs from
fully developed fluid turbulence. Here we present new experimental results with
better statistics which show that the linear model propose by C. Beck does not
capture the experimental observations.


title: Analogy between a two-well Bose-Einstein condensate and atom diffraction

abstract:
  We compare the dynamics of a Bose-Einstein condensate in two coupled
potential wells with atoms diffracting from a standing light wave. The
corresponding Hamiltonians have an identical appearance, but with a different
set of commutation rules. Well-known diffraction phenomena as Pendellosung
oscillations between opposite momenta in the case of Bragg diffraction, and
adiabatic transitions between momentum states are shown to have analogies in
the two-well case. They represent the collective exchange of a fixed number of
atoms between the wells.


title: Extended Recurrence Plot Analysis and its Application to ERP Data

abstract:
  We present new measures of complexity and their application to event related
potential data. The new measures base on structures of recurrence plots and
makes the identification of chaos-chaos transitions possible. The application
of these measures to data from single-trials of the Oddball experiment can
identify laminar states therein. This offers a new way of analyzing
event-related activity on a single-trial basis.

categories: physics.comp-ph nlin.CD physics.bio-ph physics.data-an q-bio.QM


title:
A mapping approach to synchronization in the "Zajfman trap": stability
  conditions and the synchronization mechanism

abstract:
  We present a two particle model to explain the mechanism that stabilizes a
bunch of positively charged ions in an "ion trap resonator" [Pedersen etal,
Phys. Rev. Lett. 87 (2001) 055001]. The model decomposes the motion of the two
ions into two mappings for the free motion in different parts of the trap and
one for a compressing momentum kick. The ions' interaction is modelled by a
time delay, which then changes the balance between adjacent momentum kicks.
Through these mappings we identify the microscopic process that is responsible
for synchronization and give the conditions for that regime.


title:
Orbital magnetism in axially deformed sodium clusters: From scissors
  mode to dia-para magnetic anisotropy

abstract:
  Low-energy orbital magnetic dipole excitations, known as scissors mode (SM),
are studied in alkali metal clusters. Subsequent dynamic and static effects are
explored. The treatment is based on a self-consistent microscopic approach
using the jellium approximation for the ionic background and the Kohn-Sham mean
field for the electrons. The microscopic origin of SM and its main features
(structure of the mode in light and medium clusters, separation into low- and
high-energy plasmons, coupling high-energy M1 scissors and E2 quadrupole
plasmons, contributions of shape isomers, etc) are discussed. The scissors M1
strength acquires large values with increasing cluster size. The mode is
responsible for the van Vleck paramagnetism of spin-saturated clusters. Quantum
shell effects induce a fragile interplay between Langevin diamagnetism and van
Vleck paramagnetism and lead to a remarkable dia-para anisotropy in magnetic
susceptibility of particular light clusters. Finally, several routes for
observing the SM experimentally are discussed.


title: Fundamental Research and Developing Countries

abstract:
  In the first part of this report, I discuss the sociological role of
fundamental research in Developing Countries (DC) and how to realize this
program. In the second part, I give a brief and elementary introduction to the
field of high-energy physics (HEP), accessible to a large audience not
necessary physicists. The aim of this report is to make politicians and
financial backers aware on the long-term usefulness of fundamental research in
DC and on the possible globalisation of HEP and, in general, of science.

categories: physics.soc-ph hep-ph hep-th physics.ed-ph physics.pop-ph


title: On the extrapolation of perturbation series

abstract:
  We discuss certain special cases of algebraic approximants that are given as
zeroes of so-called "effective characteristic polynomials" and their
generalization to a multiseries setting. These approximants are useful for the
convergence acceleration or summation of quantum mechanical perturbation
series. Examples will be given and some properties will be discussed.


title:
Ionospheric (H-atom) Tomography: a Feasibility Study using GNSS
  Reflections

abstract:
  In this report we analyze the feasibility of ionospheric monitoring using
GNSS technology. The focus will be on the use of LEO GNSS data, exploiting GNSS
Reflections, Navigation and Occultation TEC measurements. In order to attack
this question, we have simulated GNSS ionospheric TEC data as it would be
measured from a polar LEO (exploiting Navigation, Occultation and Reflection
TEC data) and IGS ground stations, through the use of a climatic ionospheric
model (we have explored both NeQuick and PIM). We have then developed a new
tomographic approach inspired on the physics of the hydrogen atom, which has
been compared to previous successful but somewhat awkward methods (using a
voxel representation) and employed to retrieve the Electronic Density field
from the simulated TEC data. These tomographic inversion results using
simulated data demonstrate the significant impact of GNSS-R and GNSS-NO data:
3D ionospheric Electron Density fields are retrieved over the oceans quite
accurately, even as, in the spirit of this initial study, the simulation and
inversion approaches avoided intensive computation and sophisticated
algorithmic elements (spatio-temporal smoothing). We conclude that GNSS-R data
can contribute significantly to the GIOS (Global/GNSS Ionospheric Observation
System).


title: Adsorption-desorption noise can be used for improving selectivity

abstract:
  Small chemical sensors are subjected to adsorption-desorption fluctuations
which usually considered as noise contaminating useful signal. Based on
temporal properties of this noise, it is shown that it can be made useful if
proper processed. Namely, the signal, which characterizes the total amount of
adsorbed analyte, should be subjected to a kind of amplitude discrimination (or
level crossing discrimination) with certain threshold. When the amount is equal
or above the threshold, the result of discrimination is standard dc signal,
otherwise it is zero. Analytes are applied at low concentration: the mean
adsorbed amount is below the threshold. The threshold is achieved from time to
time thanking to the fluctuations. The signal after discrimination is averaged
over a time window and used as the output of the whole device. Selectivity of
this device is compared with that of its primary adsorbing sites, based on
explicit description of the threshold-crossing statistics. It is concluded that
the whole sensor may have much better selectivity than do its individual
adsorbing sites.


title:
Dynamical stabilization of classical multi electron targets against
  autoionization

abstract:
  We demonstrate that a recently published quasiclassical M\oller type approach
[Geyer and Rost 2002, J. Phys. B 35 1479] can be used to overcome the problem
of autoionization, which arises in classical trajectory calculations for many
electron targets. In this method the target is stabilized dynamically by a
backward--forward propagation scheme. We illustrate this refocusing and present
total cross sections for single and double ionization of helium by electron
impact.


title: Rejection of the Light Quantum: The Dark Side of Niels Bohr

abstract:
  Evidence is recalled of the strong opposition of Niels Bohr, at the time of
the Old Quantum Theory 1.913-25, to the Lichtquanten hypothesis of Einstein.
Some episodes with H.A. Kramers, J.C. Slater and W. Heisenberg are recollected;
Bohr's changing point of view is traced back to some philosophical antecedents
and to his endeavour to deduce quantum results from the Correspondence
Principle. Some consequences for the future interpretation of Quantum
Mechanics, specially to the Complementarity Principle, are considered.


title: Self-Similarity Limits of Genomic Signatures

abstract:
  It is shown that metric representation of DNA sequences is one-to-one. By
using the metric representation method, suppression of nucleotide strings in
the DNA sequences is determined. For a DNA sequence, an optimal string length
to display genomic signature in chaos game representation is obtained by
eliminating effects of the finite sequence. The optical string length is
further shown as a self- similarity limit in computing information dimension.
By using the method, self-similarity limits of bacteria complete genomic
signatures are further determined.


title: Inconsistent Universe

abstract: Physics is introduced as a semantics of a formal set theory.


title:
Why helicity injection causes coronal flux tubes to develop an axially
  invariant cross-section

abstract:
  It is shown that electric current flowing along an axially non-uniform
magnetic flux tube produces an associated non-linear, non-conservative axial
MHD force which pumps plasma from regions where the flux tube diameter is small
to regions where it is large. In particular, this force will ingest plasma into
the ends of a fat, initially potential flux tube and then pump the ingested
plasma towards the middle bulge, thereby causing mass accumulation at the
bulge. The ingested plasma convects frozen-in toroidal magnetic flux which
accumulates at the middle as well. Flux accumulation at the bulge has the
remarkable consequence of causing the bulge to diminish so that the flux tube
becomes axially uniform as observed in coronal loops. Stagnation of the
convergent plasma flow at the middle heats the plasma. A small number of tail
particles bouncing synchronously between approaching fluid elements can be
Fermi-accelerated to very high energies. Since driving a current along a flux
tube is tantamount to helicity injection into the flux tube, this mass
ingestion, heating, and straightening should be ubiquitous to helicity
injection processes.


title: Diffusion-limited reaction for the one-dimensional trap system

abstract:
  We have previously discussed the one-dimensional multitrap system of finite
range and found the somewhat unexpected result that the larger is the number of
imperfect traps the higher is the transmission through them. We discuss in this
work the effect of a small number of such traps arrayed along either a constant
or a variable finite spatial section. It is shown that under specific
conditions, to be described in the following, the remarked high transmission
may be obtained for this case also. Thus, compared to the theoretical large
number of traps case these results may be experimentally applied to real
phenomena


title: On the writhe of non-closed curves

abstract:
  The writhe of a space curve fragment is considered for various boundary
conditions. An expression for the writhe as a function of arclength for an
arbitrary space curve is obtained. The formula is built on the base of closing
the tangent indicatrix with a geodesic. The corresponding closure of a curve in
3-space is explicitly constructed. The addition rule for writhe is formulated.
A relationship connecting the writhe with the Gauss integral over the open
curve is presented. The single and double regular helical shapes are examined
as examples.


title: Submarine landslides and local tsunami waves (Corinthos Gulf, Greece)

abstract:
  The problem of submarine sediment slide which generates the surface water
waves is considered. To simulate numerically the landslide motion it is used
the method which permits to take into account detailed rheological properties
of slide body constituents. The numerical simulation of landslide-induced
surface water waves is performed on the basis of nonlinear shallow water
equations. It is studied a landslide behavior for two values of maximal
friction angle. The detailed comparison of landslide dynamics and evolution of
landslide-induced surface water waves during sliding is performed. Also, the
evolution of dipolar water wave generated in the beginning of sediment sliding
is studied. It is obtained that this dipolar wave is then transformed in two
wave groups: crest and trough coming seaward and trough accompanied by crest
coming to the shoreline. The second wave group leads firstly to sea recession
from the beach and only then to large runup (tsunami wave with first negative
phase).


title:
Evidence for Bound and Free Water Species in the Hydration Shell of an
  Aqueous Micelle

abstract:
  Our atomistic molecular dynamics simulations reveal the existence of bound
and free water molecules in the hydration layer of an aqueous micelle. The
bound water molecules can be either singly or doubly hydrogen bonded to the
polar head group on the surface of the micelle. The ratio of bound to free
water is found to be approximately equal to 9:1 at 300 K.


title: Polynomial map symplectic algorithm

abstract:
  Long-term stability studies of nonlinear Hamiltonian systems require
symplectic integration algorithms which are both fast and accurate. In this
paper, we study a symplectic integration method wherein the symplectic map
representing the Hamiltonian system is refactorized using polynomial symplectic
maps. This method is analyzed in detail for the three degree of freedom case.
We obtain explicit formulas for the action of the constituent polynomial maps
on phase space variables.


title:
Gamma-ray measurements of naturally occurring radioactive samples from
  Cyprus characteristic geological rocks

abstract:
  Using high-resolution gamma-ray spectroscopy, the terrestrial gamma radiation
in all the predominant types of geological rock formations appearing in Cyprus
was measured. Soil samples were collected from each rock type, sealed in
1-litre plastic Marinelli beakers, and measured in the laboratory for 24 hours
each. From the measured gamma-ray spectra, activity concentrations were
determined for Th-232 (range from 1.3 to 52.8 Bq/kg), U-238 (from 0.9 to 90.3
Bq/kg) and K-40 (from 13 to 894 Bq/kg). Elemental concentrations mean values of
(2.8 +- 0.7) ppm, (1.3 +- 0.3) ppm and (0.6 +- 0.1) % were extracted, for
thorium, uranium and potassium, respectively. Absorbed dose rates in air
outdoors were calculated to be in the range of 0.1-50 nGy/h, depending on the
geological features, with an overall mean value of (14.7 +- 7.3) nGy/h. The
corresponding effective dose rates per person outdoors were estimated to be
between 0.1 and 61.4 microSv/y, assuming a 20% occupancy factor.


title: Laser Cooling of Nuclear Beams in Storage Rings

abstract:
  Laser cooling of nuclear beams in storage rings is discussed. The main
properties of nuclei with isomeric levels in the range E<50 keV are presented.


title:
The evolution of three-dimensionally localized vortices in shear flows.
  Linear theory

abstract:
  The evolution of a small-amplitude localized vortex disturbance in an
unbounded shear flow with the linear velocity profile is investigated. Based on
the exact solution of the initial problem for basic flow, a revision is made of
the theoretical approach (suggested by Levinski (1991) and subsequently further
developed in a series of other publications) in which the vortex evolution is
described in terms of Fluid Impulse of the vortex "core". Although the
theoretical predictions obtained on the basis of this approach were excellently
confirmed in subsequent experimental studies, its inconsistency is demonstrated
in this study.
  According to the solution obtained, the localized vortex increases slowly (as
power-law with the time) and attains an almost "horizontal" orientation, unlike
the previous theory (Levinski, 1991) that predicts the more rapid growth and
vortex orientation at the angle of 45 degrees to the flow direction. On the
other hand, just the rapid increase and the angle of 45 degrees to the outer
flow direction are characteristic for hairpin vortices observed in turbulent
boundary layers or artificially synthesized vortices in laminar boundary
layers. Thus the issue of adequate theoretical interpretation of the evolution
of localized vortices is again on the agenda.


title:
Noise-Tolerant Streaming Real-Time Data Acquisition Fabric for Pulsed
  Accelerators

abstract:
  A noise-tolerant data communications fabric has been developed to meet the
real-time data acquisition and control requirements of fast feedback loops,
machine protection systems, pulse-to-pulse sequencing, and machine-experiment
communications at next-generation pulsed accelerators such as the Next Linear
Collider ("NLC"). The fabric is constructed from "platform" or
"system-on-a-chip" field programmable gate arrays ("FPGAs") containing embedded
processors, block memory, and multi-gigabit serial transceivers interconnected
via an array of point-to-point fiber-optic physical links for standard networks
such as gigabit Ethernet. The FPGA-based link hardware segments messages of
varying priorities into a continuous sequence of fixed-length data cells,
interrupting the cell stream of lower priority messages with those comprising
higher priority traffic. A high level of noise-tolerance is provided by
dedicating almost half the contents of each cell to Reed-Solomon forward error
correcting code ("ECC") data. Further reliability is achieved by hardware
implementation of algorithms for cell-by-cell receipt acknowledgment, receipt
timeout and retransmission after a tunable round-trip propagation delay, and
separate backpressure flow control for each priority.


title: Superposition Principle and Young Type Double-Slit Experiment in Vacuum

abstract:
  In this study, it is shown with reasons that superposition principle does not
work in vacuum. This case can be observed by Young type double slit experiment
to be carried out. Since field-field interaction is carried through charged
particles, in the absence of charged particles linear superposition of two
fields is not possible and interference will not be observed.


title:
Gamma radiation measurements and dose rates in commercially-used natural
  tiling rocks (granites)

abstract:
  The gamma radiation in samples of a variety of natural tiling rocks
(granites) imported in Cyprus for use in the building industry was measured,
employing high-resolution gamma-ray spectroscopy. The rock samples were
pulverized, sealed in 1 litre plastic Marinelli beakers, and measured in the
laboratory with an accumulating time between 10 and 14 hours each. From the
measured gamma-ray spectra, activity concentrations were determined for Th-232
(range from 1 to 906 Bq/kg), U-238 (from 1 to 588 Bq/kg) and K-40 (from 50 to
1606 Bq/kg). The total absorbed dose rates in air calculated from the
concentrations of the three radionuclides, Th-232 and U-238 series and K-40,
ranged from 7 to 1209 nGy/h for full utilization of the materials, from 4 to
605 nGy/h for half utilization and from 2 to 302 nGy/h for one quarter
utilization. The total effective dose rates per person indoors were determined
to be between 0.02 to 2.97 mSv/y for half utilization of the materials.
Applying dose criteria recently recommended by the EU for superficial
materials, 25 of the samples meet the exemption dose limit of 0.3 mSv/y, two of
them meet the upper dose limit of 1 mSv/y and only one exceeds clearly this
limit.


title:
Indoor radon (Rn-222) concentration measurements in Cyprus using
  high-sensitivity portable detectors

abstract:
  Using high--sensitivity radon (Rn-222) portable detectors (passive electronic
devices of the type RADIM3), the airborne Rn-222 concentration in the interior
of various Cypriot buildings and dwellings was measured. For each preselected
building and dwelling, a calibrated detector was put into a closed room, and
the Rn-222 concentration was registered in sampling intervals of 2 to 4 hours
for a total counting time of typically 48 hours. Rn-222 activity concentrations
were found to be in the range of 6.2 to 102.8 Bq/m**3, with an overall
arithmetic mean value of (19.3 +- 14.7) Bq/m**3. This value is by a factor of
two below the world average (population-weighted) value of 39 Bq/m**3. The
total annual effective dose equivalent to the Cypriot population was calculated
to be between 0.16 and 2.6 mSv with an overall arithmetic mean value of (0.49
+- 0.37) mSv.


title:
Development prospects and stability limits of the mid-IR Kerr-lens
  mode-locked lasers

abstract:
  The Kerr-lens mode locking ability and the ultrashort pulse characteristics
are analyzed numerically for the Cr-doped ZnTe, ZnSe, ZnS active media. The
advantages of these materials for the femtosecond lasing within 2 - 3 $\mu$m
spectral range are demonstrated.


title:
The Interplanetary Magnetic Field and Solar Wind Driven Magnetospheric
  Reconfiguration

abstract:
  The magnetic disturbances are associated with electric currents as it is well
checked at laboratory room scales and described by the Maxwell's equations of
electromagnetic field. The analysis of spacecraft observations for more than a
quarter of a century failed to provide a self-consistent three-dimensional
picture of the solar wind-magnetosphere dynamo generated magnetospheric and
ionospheric current systems. The proposed solar wind and the interplanetary
magnetic field (IMF) driven reconfiguration of the earth's magnetosphere
directly accounts for the observed magnetic disturbances. So role of the
magnetospheric currents in creation of the magnetic disturbances is
reconsidered in accordance with some poorly understood observations. A
quantitative agreement with observations is demonstrated and a laboratory
experiment to test the suggested model of the solar wind/IMF-magnetosphere
interaction is described.


title:
Coarse Molecular Dynamics of a Peptide Fragment: Free Energy, Kinetics,
  and Long-Time Dynamics Computations

abstract:
  We present a ``coarse molecular dynamics'' approach and apply it to studying
the kinetics and thermodynamics of a peptide fragment dissolved in water. Short
bursts of appropriately initialized simulations are used to infer the
deterministic and stochastic components of the peptide motion parametrized by
an appropriate set of coarse variables. Techniques from traditional numerical
analysis (Newton-Raphson, coarse projective integration) are thus enabled;
these techniques help analyze important features of the free-energy landscape
(coarse transition states, eigenvalues and eigenvectors, transition rates,
etc.). Reverse integration of (irreversible) expected coarse variables backward
in time can assist escape from free energy minima and trace low-dimensional
free energy surfaces. To illustrate the ``coarse molecular dynamics'' approach,
we combine multiple short (0.5-ps) replica simulations to map the free energy
surface of the ``alanine dipeptide'' in water, and to determine the ~ 1/(1000
ps) rate of interconversion between the two stable configurational basins
corresponding to the alpha-helical and extended minima.


title:
Testing the stability of fundamental constants with the 199Hg+
  single-ion optical clock

abstract:
  Over a two-year duration, we have compared the frequency of the 199Hg+ 5d106s
2S 1/2 (F=0)<-> 5d9 6s2 2D 5/2 (F=2) electric-quadrupole transition at 282 nm
with the frequency of the ground-state hyperfine splitting in neutral 133Cs.
These measurements show that any fractional time variation of the ratio
nu(Cs)/nu(Hg) between the two frequencies is smaller than +/- 7 10^-15 / yr (1
sigma uncertainty). According to recent atomic structure calculations, this
sets an upper limit to a possible fractional time variation of g(Cs) m_e / m_p
alpha^6.0 at the same level.


title:
Analyzing neural responses to natural signals: Maximally informative
  dimensions

abstract:
  We propose a method that allows for a rigorous statistical analysis of neural
responses to natural stimuli which are non-Gaussian and exhibit strong
correlations. We have in mind a model in which neurons are selective for a
small number of stimulus dimensions out of a high dimensional stimulus space,
but within this subspace the responses can be arbitrarily nonlinear. Existing
analysis methods are based on correlation functions between stimuli and
responses, but these methods are guaranteed to work only in the case of
Gaussian stimulus ensembles. As an alternative to correlation functions, we
maximize the mutual information between the neural responses and projections of
the stimulus onto low dimensional subspaces. The procedure can be done
iteratively by increasing the dimensionality of this subspace. Those dimensions
that allow the recovery of all of the information between spikes and the full
unprojected stimuli describe the relevant subspace. If the dimensionality of
the relevant subspace indeed is small, it becomes feasible to map the neuron's
input-output function even under fully natural stimulus conditions. These ideas
are illustrated in simulations on model visual and auditory neurons responding
to natural scenes and sounds, respectively.


title:
Comment on "Stimulated Raman adiabatic passage from an atomic to a
  molecular Bose-Einstein condensate"

abstract:
  Collective two-color photoassociation of a freely-interacting 87Rb
Bose-Einstein condensate is theoretically examined, focusing on stimulated
Raman adiabatic passage (STIRAP) from an atomic to a stable molecular
condensate. In particular, Drummond et al. [Phys. Rev. A 65, 063619 (2002);
cond-mat/0110578] have predicted that particle-particle interactions can limit
the efficiency of collective atom-molecule STIRAP, and that optimizing the
laser parameters can partially overcome this limitation. We suggest that the
molecular conversion efficiency can be further improved by treating the initial
condensate density as an optimization parameter.

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


title:
A Search for Variations of Fundamental Constants using Atomic Fountain
  Clocks

abstract:
  Over five years we have compared the hyperfine frequencies of 133Cs and 87Rb
atoms in their electronic ground state using several laser cooled 133Cs and
87Rb atomic fountains with an accuracy of ~10^{-15}. These measurements set a
stringent upper bound to a possible fractional time variation of the ratio
between the two frequencies : (d/dt)ln(nu_Rb/nu_Cs)=(0.2 +/- 7.0)*10^{-16}
yr^{-1} (1 sigma uncertainty). The same limit applies to a possible variation
of the quantity (mu_Rb/mu_Cs)*alpha^{-0.44}, which involves the ratio of
nuclear magnetic moments and the fine structure constant.

categories: physics.atom-ph astro-ph gr-qc hep-ex hep-ph


title: Computation in a single neuron: Hodgkin and Huxley revisited

abstract:
  A spiking neuron ``computes'' by transforming a complex dynamical input into
a train of action potentials, or spikes. The computation performed by the
neuron can be formulated as dimensional reduction, or feature detection,
followed by a nonlinear decision function over the low dimensional space.
Generalizations of the reverse correlation technique with white noise input
provide a numerical strategy for extracting the relevant low dimensional
features from experimental data, and information theory can be used to evaluate
the quality of the low--dimensional approximation. We apply these methods to
analyze the simplest biophysically realistic model neuron, the Hodgkin--Huxley
model, using this system to illustrate the general methodological issues. We
focus on the features in the stimulus that trigger a spike, explicitly
eliminating the effects of interactions between spikes. One can approximate
this triggering ``feature space'' as a two dimensional linear subspace in the
high--dimensional space of input histories, capturing in this way a substantial
fraction of the mutual information between inputs and spike time. We find that
an even better approximation, however, is to describe the relevant subspace as
two dimensional, but curved; in this way we can capture 90% of the mutual
information even at high time resolution. Our analysis provides a new
understanding of the computational properties of the Hodgkin--Huxley model.
While it is common to approximate neural behavior as ``integrate and fire,''
the HH model is not an integrator nor is it well described by a single
threshold.


title:
An information theoretic approach to the functional classification of
  neurons

abstract:
  A population of neurons typically exhibits a broad diversity of responses to
sensory inputs. The intuitive notion of functional classification is that cells
can be clustered so that most of the diversity is captured in the identity of
the clusters rather than by individuals within clusters. We show how this
intuition can be made precise using information theory, without any need to
introduce a metric on the space of stimuli or responses. Applied to the retinal
ganglion cells of the salamander, this approach recovers classical results, but
also provides clear evidence for subclasses beyond those identified previously.
Further, we find that each of the ganglion cells is functionally unique, and
that even within the same subclass only a few spikes are needed to reliably
distinguish between cells.


title: Fast Calculations in Nonlinear Collective Models of Beam/Plasma Physics

abstract:
  We consider an application of variational-wavelet approach to nonlinear
collective models of beam/plasma physics: Vlasov/Boltzmann-like reduction from
general BBGKY hierachy. We obtain fast convergent multiresolution
representations for solutions which allow to consider polynomial and rational
type of nonlinearities. The solutions are represented via the multiscale
decomposition in nonlinear high-localized eigenmodes (waveletons).

categories: physics.plasm-ph math-ph math.MP nlin.PS


title: Physical limits to biochemical signaling

abstract:
  Many crucial biological processes operate with surprisingly small numbers of
molecules, and there is renewed interest in analyzing the impact of noise
associated with these small numbers. Twenty--five years ago, Berg and Purcell
showed that bacterial chemotaxis, where a single celled organism must respond
to small changes in concentration of chemicals outside the cell, is limited
directly by molecule counting noise, and that aspects of the bacteria's
behavioral and computational strategies must be chosen to minimize the effects
of this noise. Here we revisit and generalize their arguments to estimate the
physical limits to signaling processes within the cell, and argue that recent
experiments are consistent with performance approaching these limits.


title:
Random sampling of an AC source: A tool to teach probabilistic
  observations

abstract:
  An undergraduate level experiment is described to demonstrate the role of
probabilistic observations in physics. A capacitor and a DC voltmeter are used
to randomly sample an AC voltage source. The resulting probability distribution
is analyzed to extract information about the AC source. Different
characteristic probability distributions arising from various AC waveforms are
calculated and experimentally measured. The reconstruction of the AC waveform
is demonstrated from the measured probability distribution under certain
restricted circumstances. The results are also compared with a simulated data
sample. We propose this as a pedagogical tool to teach probabilistic
measurements and their manipulations.


title: Geometry of Time and Dimensionality of Space

abstract:
  One of the most distinguished features of our algebraic geometrical, pencil
concept of space-time is the fact that spatial dimensions and time stand, as
far as their intrinsic structure is concerned, on completely different
footings: the former being represented by pencils of lines, the latter by a
pencil of conics. As a consequence, we argue that even at the classical
(macroscopic) level there exists a much more intricate and profound coupling
between space and time than that dictated by (general) relativity theory. It is
surmised that this coupling can be furnished by so-called Cremona (or
birational) transformations between two projective spaces of three dimensions,
being fully embodied in the structure of configurations of their fundamental
elements. We review properties of some of the simplest Cremona transformations
and show that the corresponding "fundamental" space-times exhibit an intimate
connection between the extrinsic geometry of time dimension and the
dimensionality of space. Moreover, these Cremonian space-times seem to provide
us with a promising conceptual basis for the possible reconciliation between
two extreme concepts of (space-)time, viz. physical and psychological. Some
speculative remarks in this respect are made.


title: Correlation structure in nondipole photoionization

abstract:
  The nondipole parameters that characterize the angular disribution of the
photoelectrons from the 3d subshell of Cs are found to be altered qualitatively
by the inclusion of correlation in the form of interchannel coupling between
the $3d_{3/2}$ and $3d_{5/2}$ photoionization channels. A prominent
characteristic maximum is predicted only in the parameters for $3d_{5/2}$
photoionization, while the effect for $3d_{3/2}$ is rather weak. The results
are obtained within the framework of the Generalized Random Phase Approximation
with Exchange (GRPAE), which in addition to the RPAE effects takes into account
the rearrangement of all atomic electrons due to the creation of a 3d vacancy.


title: Causality, light speed constancy and local action principle

abstract:
  In 1905 A. Einstein, from the experiments of Michelson and Morley in 1887,
enunciates the light speed constancy principle in the inertial frames of
reference. However, this principle was pointed by the equations of the
electromagnetism of J. C. Maxwell in 1865. The prediction of the Maxwell
equations is due to in the most basic principle of the science, the principle
of causality, is the reason of the light speed constancy. This article shown
how, only with the causality principle, we can deduce the properties of the
light. At the end of the article we used the causality relativistic definition
to approach the local action principle, as well as to solve the paradox that
implies the EPR theorem.


title: Modeling DNA loops using the theory of elasticity

abstract:
  A versatile approach to modeling the conformations and energetics of DNA
loops is presented. The model is based on the classical theory of elasticity,
modified to describe the intrinsic twist and curvature of DNA, the DNA bending
anisotropy, and electrostatic properties. All the model parameters are
considered to be functions of the loop arclength, so that the DNA
sequence-specific properties can be modeled. The model is applied to the test
case study of a DNA loop clamped by the lac repressor protein. Several
topologically different conformations are predicted for various lengths of the
loop. The dependence of the predicted conformations on the parameters of the
problem is systematically investigated. Extensions of the presented model and
the scope of the model's applicability, including multi-scale simulations of
protein-DNA complexes and building all-atom structures on the basis of the
model, are discussed.


title: Finite-Time Singularity Signature of Hyperinflation

abstract:
  We present a novel analysis extending the recent work of Mizuno et al. [2002]
on the hyperinflations of Germany (1920/1/1-1923/11/1), Hungary
(1945/4/30-1946/7/15), Brazil (1969-1994), Israel (1969-1985), Nicaragua
(1969-1991), Peru (1969-1990) and Bolivia (1969-1985). On the basis of a
generalization of Cagan's model of inflation based on the mechanism of
``inflationary expectation'' or positive feedbacks between realized growth rate
and people's expected growth rate, we find that hyperinflations can be
characterized by a power law singularity culminating at a critical time $t_c$.
Mizuno et al.'s double-exponential function can be seen as a discrete time-step
approximation of our more general nonlinear ODE formulation of the price
dynamics which exhibits a finite-time singular behavior. This extension of
Cagan's model, which makes natural the appearance of a critical time $t_c$, has
the advantage of providing a well-defined end of the clearly unsustainable
hyperinflation regime. We find an excellent and reliable agreement between
theory and data for Germany, Hungary, Peru and Bolivia. For Brazil, Israel and
Nicaragua, the super-exponential growth seems to be already contaminated
significantly by the existence of a cross-over to a stationary regime.

categories: physics.soc-ph cond-mat.soft physics.gen-ph q-fin.ST


title:
Investigation of the performance of an optimised MicroCAT, a GEM and
  their combination by simulations and current measurements

abstract:
  A MicroCAT (Micro Compteur A Trous) structure which is used for avalanche
charge multiplication in gas filled radiation detectors has been optimised with
respect to maximum electron transparency and minimum ion feedback. We report on
the charge transfer behaviour and the achievable gas gain of this device. A
three-dimensional electron and ion transfer simulation is compared to results
derived from electric current measurements. Similarly, we present studies of
the charge transfer behaviour of a GEM (Gas Electron Multiplier) by current
measurements and simulations. Finally, we investigate the combination of the
MicroCAT and the GEM by measurements with respect to the performance at
different voltage settings, gas mixtures and gas pressures.


title:
VaR-Efficient Portfolios for a Class of Super- and Sub-Exponentially
  Decaying Assets Return Distributions

abstract:
  Using a family of modified Weibull distributions, encompassing both
sub-exponentials and super-exponentials, to parameterize the marginal
distributions of asset returns and their multivariate generalizations with
Gaussian copulas, we offer exact formulas for the tails of the distribution
$P(S)$ of returns $S$ of a portfolio of arbitrary composition of these assets.
We find that the tail of $P(S)$ is also asymptotically a modified Weibull
distribution with a characteristic scale $\chi$ function of the asset weights
with different functional forms depending on the super- or sub-exponential
behavior of the marginals and on the strength of the dependence between the
assets. We then treat in details the problem of risk minimization using the
Value-at-Risk and Expected-Shortfall which are shown to be (asymptotically)
equivalent in this framework.


title:
Proposal of an experimental strategy to introduce relativity in
  elementary physics courses

abstract:
  This contribution shows that the main topics of Relativity can be discussed
at an elementary level and in a considerable extent - including the formal
results of "Time Dilation" and "Lorentz Contraction" - by a minor modification
of the usual mathematical formalism employed to describe uniform and
accelerated motion. The proposed strategy begins with a "free-fall" experiment,
followed by a discussion of the results in order to include deviations of the
experimental data with respect to the conventional kinematics model.


title: Spectral Statistics of RR Intervals in ECG

abstract:
  The statistical properties (fluctuations) of heartbeat intervals (RR
intervals) in ECG are studied and compared with the predictions of Random
Matrix Theory (RMT). It is found that heartbeat intervals only locally exhibit
the fluctuation patterns (universality) predicted by the RMT. This finding
shows that heartbeat dynamics is of the mixed type where regular and irregular
(chaotic) regimes coexist and the Berry-Robnik theory can be applied. It is
also observed that the distribution of heartbeat intervals is well described by
the one-parameter Brody distribution. The parameter $\beta $ of the Brody
distribution is seen to be connected with the dynamical state of the heart.


title: A model of population dynamics - further investigations

abstract:
  The population is composed of individuals characterised by their genetic
strings, phenotypes and ages. We discuss the influence of probabilities of
survival of the individuals on the dynamics and phenotypic variability of the
population.
  We show that constant survival probabilities of individuals are propitious
for preserving phenotypic variability of the population. For constant survival
probabilities oscillations of 'the average fitness' of the population and
normal distributions of the phenotypes are observed. When the probabilities of
survival are directly proportinal to the individuals' adaptations the
population can reach the maximum possible average adaptation, but the
phenotypic variability of the population is completely lost and oscillations of
'the average fitness' of the population do not occur.
  We also investigate the behaviour of the population caused by the
probabilities of survival that partly depend on the individuals' adaptations.
The role of the length of the individuals' genetic strings is considered here.


title: A note on the nature of the de Broglie waves

abstract:
  In this note we will first argue that there is evidence in supporting the
view that de Broglie waves have a gravitational origin. In view of the extreme
weakness of the gravitational field, however, this seems to be an unlikely
proposition. We consider the problem of the atom in the light of a proposed
electron theory [physics/0212013] and show that in this theory an insignificant
perturbation in the gravitational field might in effect be amplified by
astonishingly large orders of magnitudes. On this basis we then propose a
realistic model of an atom where the electron continually tunnels through the
electrostatic field of the proton and the de Broglie waves take on the role of
the missing electrostatic interactions. Although the discussion is a
qualitative one, and as such may not be considered as being conclusive, never
the less, we believe that on the evidence presented here the possibility of a
gravitational origin for the de Broglie waves must be seriously considered.


title: What causes a neuron to spike?

abstract:
  The computation performed by a neuron can be formulated as a combination of
dimensional reduction in stimulus space and the nonlinearity inherent in a
spiking output. White noise stimulus and reverse correlation (the
spike-triggered average and spike-triggered covariance) are often used in
experimental neuroscience to `ask' neurons which dimensions in stimulus space
they are sensitive to, and to characterize the nonlinearity of the response. In
this paper, we apply reverse correlation to the simplest model neuron with
temporal dynamics--the leaky integrate-and-fire model--and find that even for
this simple case standard techniques do not recover the known neural
computation. To overcome this, we develop novel reverse correlation techniques
by selectively analyzing only `isolated' spikes, and taking explicit account of
the extended silences that precede these isolated spikes. We discuss the
implications of our methods to the characterization of neural adaptation.
Although these methods are developed in the context of the leaky
integrate-and-fire model, our findings are relevant for the analysis of spike
trains from real neurons.


title: Fuzzy Space Time, Quantum Geometry and Cosmology

abstract:
  It is argued that a noncommutative geometry of spacetime leads to a
reconciliation of electromagnetism and gravitation while providing an
underpinning to Weyl's geometry. It also leads to a cosmology consistent with
observation. A few other ramifications are also examined.


title:
Accurate Adiabatic Connection Curve Beyond the Physical Interaction
  Strength

abstract:
  The adiabatic connection curve of density functional theory (DFT) is
accurately calculated beyond the physical interaction strength for Hooke's
atom, two interacting electrons in a harmonic well potential. Extrapolation of
the accurate curve to the infinite coupling limit agrees well with the strictly
correlated electron (SCE) hypothesis but the approach to this limit is more
complex. The interaction strength interpolation is shown to be a good, but not
perfect, fit to the adiabatic curve. Arguments about the locality of
functionals and convexity of the adiabatic connection curve are examined in
this regime.


title: The Kustaanheimo-Stiefel transformation in geometric algebra

abstract:
  The Kustaanheimo-Stiefel (KS) transformation maps the non-linear and singular
equations of motion of the three-dimensional Kepler problem to the linear and
regular equations of a four-dimensional harmonic oscillator. It is used
extensively in studies of the perturbed Kepler problem in celestial mechanics
and atomic physics. In contrast to the conventional matrix-based approach, the
formulation of the KS transformation in the language of geometric Clifford
algebra offers the advantages of a clearer geometrical interpretation and
greater computational simplicity. It is demonstrated that the geometric algebra
formalism can readily be used to derive a Lagrangian and Hamiltonian
description of the KS dynamics in arbitrary static electromagnetic fields. For
orbits starting at the Coulomb centre, initial conditions are derived and a
framework is set up that allows a discussion of the stability of these orbits.


title: Probability Density Function of Kerr Effect Phase Noise

abstract:
  The probability density function of Kerr effect phase noise, often called the
Gordon-Mollenauer effect, is derived analytically. The Kerr effect phase noise
can be accurately modeled as the summation of a Gaussian random variable and a
noncentral chi-square random variable with two degrees of freedom. Using the
received intensity to correct for the phase noise, the residual Kerr effect
phase noise can be modeled as the summation of a Gaussian random variable and
the difference of two noncentral chi-square random variables with two degrees
of freedom. The residual phase noise can be approximated by Gaussian
distribution better than the Kerr effect phase noise without correction.


title:
Levy walk patterns in the foraging movements of spider monkeys (Ateles
  geoffroyi)

abstract:
  Scale invariant patterns have been found in different biological systems, in
many cases resembling what physicists have found in other nonbiological
systems. Here we describe the foraging patterns of free-ranging spider monkeys
(Ateles geoffroyi) in the forest of the Yucatan Peninsula, Mexico and find that
these patterns resemble what physicists know as Levy walks. First, the length
of a trajectory s constituent steps, or continuous moves in the same direction,
is best described by a power-law distribution in which the frequency of ever
larger steps decreases as a negative power function of their length. The rate
of this decrease is very close to that predicted by a previous analytical Levy
walk model to be an optimal strategy to search for scarce resources distributed
at random Viswanathan et al 1999). Second, the frequency distribution of the
duration of stops or waiting times also approximates a power-law function.
Finally, the mean square displacement during the monkeys first foraging trip
increases more rapidly than would be expected from a random walk with constant
step length, but within the range predicted for Levy walks. In view of these
results, we analyze the different exponents characterizing the trajectories
described by females and males, and by monkeys on their own or when part of a
subgroup. We discuss the origin of these patterns and their implications for
the foraging ecology of spider monkeys.


title: Classical description of pair production

abstract:
  It is shown that the classical description of pair production effect is
possible, i.e. one can describe pair production without a reference to quantum
principles. Pair production appears at statistical description of stochastic
relativistic particles. There is a special force field which is responsible for
pair production. This field is a reasonable consequence of quantum
stochasticity. Consideration of quantum systems as stochastic systems and
statistical description of them generates hydrodynamic interpretation of
quantum phenomena. In the collision problem the hydrodynamic interpretation
appears to be alternative to the conventional interpretation, based on quantum
principles and on consideration of the wave function as a principal object of
dynamics. Hydrodynamic interpretation leads to such a statement of the
collision problem, which is alternative to the conventional S-matrix theory.


title: Higher-order Continuum Approximation for Rarefied Gases

abstract:
  The Hilbert-Chapman-Enskog expansion of the kinetic equations in mean flight
times is believed to be asymptotic rather than convergent. It is therefore
inadvisable to use lower order results to simplify the current approximation as
is done in the traditional Chapman-Enskog procedure, since that is an iterative
method. By avoiding such recycling of lower order results, one obtains
macroscopic equations that are asymptotically equivalent to the ones found in
the Chapman-Enskog approach. The new equations contain higher order terms that
are discarded in the Chapman-Enskog method. These make a significant impact on
the results for such problems as ultrasound propagation. In this paper, it is
shown that these results turn out well with relatively little complication when
the expansions are carried to second order in the mean free time, for the
example of the relaxation or BGK model of kinetic theory.


title: Morphology of the universal function for the critical circle map

abstract:
  We describe the morphology of the universal function for the critical (cubic)
circle map at the golden mean, paying particular attention to the birth of
inflection points and their reproduction. In this way one can fully understand
its intricacies.


title:
Renormalization Group Analysis of the 2000-2002 anti-bubble in the US
  S&P 500 index: Explanation of the hierarchy of 5 crashes and Prediction

abstract:
  We propose a straightforward extension of our previously proposed
log-periodic power law model of the ``anti-bubble'' regime of the USA market
since the summer of 2000, in terms of the renormalization group framework to
model critical points. Using a previous work by Gluzman and Sornette (2002) on
the classification of the class of Weierstrass-like functions, we show that the
five crashes that occurred since August 2000 can be accurately modelled by this
approach, in a fully consistent way with no additional parameters. Our theory
suggests an overall consistent organization of the investors forming a
collective network which interact to form the pessimistic bearish
``anti-bubble'' regime with intermittent acceleration of the positive feedbacks
of pessimistic sentiment leading to these crashes. We develop retrospective
predictions, that confirm the existence of significant arbitrage opportunities
for a trader using our model. Finally, we offer a prediction for the unknown
future of the US S&P500 index extending over 2003 and 2004, that refines the
previous prediction of Sornette and Zhou (2002).

categories: physics.soc-ph cond-mat.soft physics.gen-ph q-fin.GN


title: Quasi-chemical study of Be$^{2+}$(aq) speciation

abstract:
  Be$^{2+}$(aq) hydrolysis can to lead to the formation of multi-beryllium
clusters, but the thermodynamics of this process has not been resolved
theoretically. We study the hydration state of an isolated Be$^{2+}$ ion using
both the quasi-chemical theory of solutions and ab initio molecular dynamics.
These studies confirm that Be$^{2+}$(aq) is tetra-hydrated. The quasi-chemical
approach is then applied to then the deprotonation of $Be(H_2O)_4^{2+}}$ to
give $BeOH(H_2O)_3{}^{+}}$. The calculated pK$_a$ of 3.8 is in good agreement
with the experimentally suggested value around 3.5. The calculated energetics
for the formation of BeOHBe$^{3+}$ are then obtained in fair agreement with
experiments.


title: Spallation Neutron Source and Other High Intensity Proton Sources

abstract:
  This lecture is an introduction to the design of a spallation neutron source
and other high intensity proton sources. It discusses two different approaches:
linac-based and synchrotron-based. The requirements and design concepts of each
approach are presented. The advantages and disadvantages are compared. A brief
review of existing machines and those under construction and proposed is also
given. An R&D program is included in an appendix.


title: Analytical Modeling of the White Light Fringe

abstract:
  We developed analytical technique for extracting the phase, visibility and
amplitude information as needed for interferometric astrometry with the Space
Interferometry Mission (SIM). Our model accounts for a number of physical and
instrumental effects, and is valid for a general case of bandpass filter. We
were able to obtain general solution for polychromatic phasors and address
properties of unbiased fringe estimators in the presence of noise. For
demonstration purposes we studied the case of rectangular bandpass filter with
two different methods of optical path difference (OPD) modulation -- stepping
and ramping OPD modulations. A number of areas of further studies relevant to
instrument design and simulations are outlined and discussed.


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

abstract:
  A new approach is developed to derive the complete spectrum of exact
interdimensional degeneracies for a quantum three-body system in D-dimensions.
The new method gives a generalization of previous methods.


title: Writhing Geometry of Open DNA

abstract:
  Motivated by recent experiments on DNA torsion-force-extension
characteristics we consider the writhing geometry of open stiff molecules. We
exhibit a cyclic motion which allows arbitrarily large twisting of the end of a
molecule via an activated process. This process is suppressed for forces larger
than femto-Newtons which allows us to show that experiments are sensitive to a
generalization of the Calugareanu-White formula for the writhe. Using numerical
methods we compare this formulation of the writhe with recent analytic
calculations.

categories: physics.bio-ph cond-mat.soft physics.class-ph q-bio


title:
Effects of curvature on hydrothermal waves instability of radial
  thermocapillary flows

abstract:
  The stability of a thermocapillary flow in an extended cylindrical geometry
is analyzed. This flow occurs in a thin liquid layer with a disk shape when a
radial temperature gradient is applied along the horizontal free surface.
Besides the aspect ratio, a second parameter related to the local curvature is
introduced to describe completely the geometrical effects. We recover classical
hydrothermal waves as predicted by Smith and Davis but the properties of these
waves are shown to evolve with the curvature parameter, thus leading to a non
uniform pattern over the cell. Moreover, it is shown that the problem is not
invariant with respect to the exchange of the hot and cold sides.


title:
On signal-noise decomposition of timeseries using the continuous wavelet
  transform: Application to sunspot index

abstract:
  We show that the continuous wavelet transform can provide a unique
decomposition of a timeseries in to 'signal-like' and 'noise-like' components:
  From the overall wavelet spectrum two mutually independent skeleton spectra
can be extracted, allowing the separate detection and monitoring in even
non-stationary timeseries of the evolution of (a) both stable but also
transient, evolving periodicities, such as the output of low dimensional
dynamical systems and (b) scale-invariant structures, such as discontinuities,
self-similar structures or noise. An indicative application to the
monthly-averaged sunspot index reveals, apart from the well-known 11-year
periodicity, 3 of its harmonics, the 2-year periodicity (quasi-biennial
oscillation, QBO) and several more (some of which detected previously in
various solar, earth-solar connection and climate indices), here proposed being
just harmonics of the QBO, in all supporting the double-cycle solar magnetic
dynamo model (Benevolenskaya, 1998, 2000). The scale maximal spectrum reveals
the presence of 1/f fluctuations with timescales up to 1 year in the sunspot
number, indicating that the solar magnetic configurations involved in the
transient solar activity phenomena with those characteristic timescales are in
a self-organized-critical state (SOC), as previously proposed for the solar
flare occurence (Lu and Hamilton, 1991).


title:
Investigation by physical methods of the possible role of telomeres in
  DNA in aging process

abstract:
  The interaction energies between the different types of bases of a single
strand of DNA molecule have been calculated. Using these original values of
energies the harmonic behavior of a number of base patterns of DNA has been
studied. In view of the great interest aroused by the discovery of the role of
the telomere segment of the DNA in the replication process and its possible
link with the aging process, we have investigated, with simple models, the
harmonic behavior of the telomeric pattern of bases as well as the
thermodynamic response in the biological system. With these results a
conclusion on the probable role of the telomeric pattern on aging has also been
drawn. Here the calculated values of harmonic frequencies of the telomeric
pattern of bases and of other possible patterns show that the telomeric pattern
is associated with the highest vibrational frequency among all patterns of base
combinations at the replication end of DNA. This seems to suggest that due to
the existing telomeric pattern being closest to the frequencies of the
electromagnetic radiation coming from sunlight, resonance of the telomeric
frequency with such radiation may be responsible for damage to the reproductive
ability of the cells and consequent aging and other problems. On the other hand
in the last part of this work we have calculated the thermal vibrational
amplitudes of the telomeric pattern and other possible patterns which show that
the amplitude for the telomeric pattern is the least, and this suggests that
the telomeric pattern is more mechanically and thermally stable than other
possible patterns in the biological environment against damage from ordinary
heat and mechanical effects.


title:
Numerical study of homogeneous dynamo based on experimental von Karman
  type flows

abstract:
  A numerical study of the magnetic induction equation has been performed on
von Karman type flows. These flows are generated by two co-axial
counter-rotating propellers in cylindrical containers. Such devices are
currently used in the von Karman sodium (VKS) experiment designed to study
dynamo action in an unconstrained flow. The mean velocity fields have been
measured for different configurations and are introduced in a periodic
cylindrical kinematic dynamo code. Depending on the driving configuration, on
the poloidal to toroidal flow ratio and on the conductivity of boundaries, some
flows are observed to sustain growing magnetic fields for magnetic Reynolds
numbers accessible to a sodium experiment. The response of the flow to an
external magnetic field has also been studied: The results are in excellent
agreement with experimental results in the single propeller case but can differ
in the two propellers case.


title: Effect of the spherical Earth on a simple pendulum

abstract:
  We consider the period of a simple pendulum in the gravitational field of the
spherical Earth. Effectively, gravity is enhanced compared with the often used
flat Earth approximation, such that the period of the pendulum is shortened. We
discuss the flat Earth approximation, and show when the corrections due to the
spherical Earth may be of interest.


title: Neutrino masses and the structure of the weak gauge boson

abstract:
  It is supposed that the electron neutrino mass is related to the structures
and masses of the $W^\pm$ and $Z^0$ bosons. Using a composite model of fermions
(described elsewhere), it is shown that the massless neutrino is not consistent
with the high values of the experimental masses of $W^\pm$ and $Z^0$.
Consistency can be achieved on the assumption that the electron-neutrino has a
mass of about 4.5 meV. Masses of the muon- and tau-neutrinos are also
estimated.


title:
Stability of the self-phase-locked pump-enhanced singly resonant
  parametric oscillator

abstract:
  Steady-state and dynamics of the self-phase-locked (3\omega ==> 2\omega,
\omega) subharmonic optical parametric oscillator are analyzed in the
pump-and-signal resonant configuration, using an approximate analytical model
and a full propagation model. The upper branch solutions are found always
stable, regardless of the degree of pump enhancement. The domain of existence
of stationary states is found to critically depend on the phase-mismatch of the
competing second-harmonic process.


title: Temperature-induced pair correlations in clusters and nuclei

abstract:
  The pair correlations in mesoscopic systems such as $nm$-size superconducting
clusters and nuclei are studied at finite temperature for the canonical
ensemble of fermions in model spaces with a fixed particle number: i) a
degenerate spherical shell (strong coupling limit), ii) an equidistantly spaced
deformed shell (weak coupling limit). It is shown that after the destruction of
the pair correlations at T=0 by a strong magnetic field or rapid rotation,
heating can bring them back. This phenomenon is a consequence of the fixed
number of fermions in the canonical ensemble.


title:
Why current-carrying magnetic flux tubes gobble up plasma and become
  thin as a result

abstract:
  It is shown that if a current-carrying magnetic flux tube is bulged at its
axial midpoint z=0 and constricted at its axial endpoints z=+h,-h, then plasma
will be accelerated from z=+h,-h towards z=0 resulting in a situation similar
to two water jets pointed at each other. The ingested plasma convects embedded,
frozen-in toroidal magnetic flux from z=+h,-h to z=0. The counter-directed
flows collide and stagnate at z=0 and in so doing (i) convert their
translational kinetic energy into heat, (ii) increase the plasma density at
z~0, and (iii) increase the embedded toroidal flux density at z~0. The increase
in toroidal flux density at z~0 increases the toroidal field Bphi and hence
increases the magnetic pinch force at z~0 and so causes a reduction of the flux
tube radius at z~0. Thus, the flux tube develops an axially uniform
cross-section, a decreased volume, an increased density, and an increased
temperature. This model is proposed as a likely hypothesis for the
long-standing mystery of why solar coronal loops are observed to be axially
uniform, hot, and bright.


title: Statistical evaporation of rotating clusters

abstract:
  Unimolecular evaporation in rotating atomic clusters is investigated using
phase space theory (PST) and molecular dynamics simulations. The rotational
densities of states are calculated in the sphere+atom approximation, and
analytical expressions are given for a radial interaction potential with the
form -C/r^p. The vibrational densities of states are calculated using Monte
Carlo simulations, and the average radial potential at finite temperature is
obtained using a recent extension of the multiple range random-walk algorithm.
These ideas are tested on simple argon clusters modelled with the Lennard-Jones
(LJ) interaction potential, at several total energies and angular momenta of
the parent cluster. Our results show that PST successfully reproduces the
simulation data, not only the average KER but its probability distribution, for
dissociations from LJ_14, for which the product cluster can effectively be
considered as spherical. Even for dissociations from the nonspherical LJ_8,
simulation results remain very close to the predictions of the statistical
theory.


title:
Two Avenues to Self-Interaction Correction within Kohn-Sham Theory:
  Unitary Invariance is the Shortcut

abstract:
  The most widely-used density functionals for the exchange-correlation energy
are inexact for one-electron systems. Their self-interaction errors can be
severe in some applications. The problem is not only to correct the
self-interaction error, but to do so in a way that will not violate
size-consistency and will not go outside the standard Kohn-Sham density
functional theory. The solution via the optimized effective potential (OEP)
method will be discussed, first for the Perdew-Zunger self-interaction
correction (whose performance for molecules is briefly summarized) and then for
the more modern self-interaction corrections based upon unitarily-invariant
indicators of iso-orbital regions. For the latter approaches, the OEP
construction is greatly simplified. The kinetic-energy-based iso-orbital
indicator $\tau^W_\sigma(\re)/\tau_\sigma(\re)$ will be discussed and plotted,
along with an alternative exchange-based indicator.


title:
To the problem of finding the transmission and reflection bands of a
  plane electromagnetic wave falling on an ideal structure

abstract:
  In the present paper we investigate the transmission and reflection band
behavior for a plane electromagnetic wave falling obliquely on an ideal layered
structure. The dependence of this behavior on the problem parameters and wave
incident angle is considered. It is shown, that in general case the band width
is a non-monotonous function of the problem parameters. A condition is found,
which defines the possibility of the contact of the transmission bands. This
condition has the same form for s and p waves. It is also shown that
irrespective of the wave polarization, the transmission coefficient equals to
the unit at the contact points.


title:
Electronic Properties of Random Polymers: Modelling Optical Spectra of
  Melanins

abstract:
  Melanins are a group of complex pigments of biological origin, widely spread
in all species from fungi to man. Among diverse types of melanins, the human
melanins, eumelanins,are brown or black nitrogen-containing pigments, mostly
known for their photoprotective properties in human skin. We have undertaken
theoretical studies aimed to understand absorption spectra of eumelanins and
their chemical precursors. The structure of the biopigment is poorly defined,
although it is believed to be composed of cross-linked heteropolymers based on
indolequinones. As a basic model of the eumelanin structure, we have chosen
pentamers containing hydroquinones (HQ) and/or 5,6-indolequinones (IQ) and/or
semiquinones (SQ) often listed as structural melanin monomers. The eumelanin
oligomers have been constructed as random compositions of basic monomers and
opitimized for the energy of bonding. Absorption spectra of model assemblies
have been calculated within the semiempirical intermediate neglect of
differential overlap (INDO) approximation. Model spectrum of eumelanin has been
further obtained by sum of independent spectra of singular polymers. By
comparison with experimental data it is shown that the INDO/CI method manages
to reproduce well characteristic properties of experimental spectrum of
synthetic eumelanins.


title:
Fundamental building blocks of eumelanins: electronic properties of
  indolequinone-dimers

abstract:
  We present results from the theoretical INDO calculations of the electronic
structure for stacked eumelanins' monomers. As basic indolic components of the
eumelanin structure 5,6-dihydroxyindole (DHI or HQ) and its oxidized forms (SQ
and IQ) were chosen. The results reveal dependency of electronic properties of
such aggregates on monomers' redox states. They point out also a tendency to
localize an extra charge on one of dimer's subunits that could be suggestive of
an electron hopping as a model mechanism forthe electron transfer in
eumelanins.


title: Transition to turbulence in particulate pipe flow

abstract:
  We investigate experimentally the influence of suspended particles on the
transition to turbulence. The particles are monodisperse and neutrally-buoyant
with the liquid. The role of the particles on the transition depends both upon
the pipe to particle diameter ratios and the concentration. For large
pipe-to-particle diameter ratios the transition is delayed while it is lowered
for small ratios. A scaling is proposed to collapse the departure from the
critical Reynolds number for pure fluid as a function of concentration into a
single master curve.


title: A linear solution to the effective four-dimensionality problem

abstract:
  In this note we formalize certain aspects of observation process in an
attempt to link the logic of the observer with properties of the observables
structures. It is shown that an observer with Boolean logic perceives her
environment as a four-dimensional Lorentzian manifold.


title:
The second harmonic generation in the symmetric well containing a
  rectangular barrier

abstract:
  The problem of determination of the maximum of second harmonic generation in
the potential well containing a rectangular barrier is considered. It is shown
that, in general, the problem of finding the ensemble of structures with
equidistant first three levels has two types of solutions.
  For the first type the second and third energy levels are located above a
rectangular barrier, and for the second type the third level is located above
the barrier only. It is also shown, that generation corresponding to the second
type of solution always is less than generation for the first one. Taking into
account the effective mass changes the problem of finding the generation
maximum for a finite depth well is exactly solved.


title: Theoretical energies and transition probabilities of argon

abstract:
  Argon energies of J=1 odd and J=2 even states, oscillator strengths of the
two lowest J=1 odd states, and line strengths for transitions between J=1 odd
and J=2 even excited states are calculated with the CI+MBPT method. The results
are in good agreement with experiment.


title:
Obervational Model for Microarcsecond Astrometry with the Space
  Interferometry Mission

abstract:
  The Space Interferometry Mission (SIM) is a space-based long-baseline optical
interferometer for precision astrometry. One of the primary objectives of the
SIM instrument is to accurately determine the directions to a grid of stars,
together with their proper motions and parallaxes, improving a priori knowledge
by nearly three orders of magnitude. The basic astrometric observable of the
instrument is the pathlength delay, a measurement made by a combination of
internal metrology measurements that determine the distance the starlight
travels through the two arms of the interferometer and a measurement of the
white light stellar fringe to find the point of equal pathlength. Because this
operation requires a non--negligible integration time to accurately measure the
stellar fringe position, the interferometer baseline vector is not stationary
over this time period, as its absolute length and orientation are
time--varying. This conflicts with the consistency condition necessary for
extracting the astrometric parameters which requires a stationary baseline
vector. This paper addresses how the time-varying baseline is ``regularized''
so that it may act as a single baseline vector for multiple stars, and thereby
establishing the fundamental operation of the instrument.


title: Entropy is a Mathematical Formula

abstract:
  The microscopic explanation of entropy has been challenged from both
experimental and theoretical point of view. The expression of entropy is
derived from the first law of thermodynamics indicating that entropy or the
second law of thermodynamics is not an independent law.


title:
Scanning the structure of ill-known spaces: Part 3. Distribution of
  topological structures at elementary and cosmic scales

abstract:
  The distribution of the deformations of elementary cells is studied in an
abstract lattice constructed from the existence of the empty set. One
combination rule determining oriented sequences with continuity of set-distance
function in such spaces provides a particular kind of spacetime-like structure
that favors the aggregation of such deformations into fractal forms standing
for massive objects. A correlative dilatation of space appears outside the
aggregates. At the large scale, this dilatation results in an apparent
expansion, while at the submicroscopic scale the families of fractal
deformations give raise to families of particle-like structure. The theory
predicts the existence of classes of spin, charges, and magnetic properties,
while quantum properties associated to mass have previously been shown to
determine the inert mass and the gravitational effects. When applied to our
observable spacetime, the model would provide the justifications for the
existence of the creation of mass in a specified kind of "void", and the
fractal properties of the embedding lattice extend the phenomenon to formal
justifications of Big-Bang-like events without need for any supply of an
extemporaneous energy.


title:
Solving seismic wave propagation in elastic media using the matrix
  exponential approach

abstract:
  Three numerical algorithms are proposed to solve the time-dependent
elastodynamic equations in elastic solids. All algorithms are based on
approximating the solution of the equations, which can be written as a matrix
exponential. By approximating the matrix exponential with a product formula, an
unconditionally stable algorithm is derived that conserves the total elastic
energy density. By expanding the matrix exponential in Chebyshev polynomials
for a specific time instance, a so-called ``one-step'' algorithm is constructed
that is very accurate with respect to the time integration. By formulating the
conventional velocity-stress finite-difference time-domain algorithm (VS-FDTD)
in matrix exponential form, the staggered-in-time nature can be removed by a
small modification, and higher order in time algorithms can be easily derived.
For two different seismic events the accuracy of the algorithms is studied and
compared with the result obtained by using the conventional VS-FDTD algorithm.


title: Theory of dark resonances for alkali vapors in a buffer-gas cell

abstract:
  We develop an analytical theory of dark resonances that accounts for the full
atomic-level structure, as well as all field-induced effects such as coherence
preparation, optical pumping, ac Stark shifts, and power broadening. The
analysis uses a model based on relaxation constants that assumes the total
collisional depolarization of the excited state. A good qualitative agreement
with experiments for Cs in Ne is obtained.


title: Geometry of the group of nonzero quaternions

abstract:
  It is shown that the group of nonzero quaternions carries a family of natural
closed Friedmann-Lema\^{\i}tre-Robertson-Walker metrics.


title: Optical Tests of Nanoengineered Liquid Mirrors

abstract:
  We describe a new technology for the fabrication of inexpensive high-quality
mirrors. We begin by chemically producing a large number of metallic
nanoparticles coated with organic ligands. The particles are then spread on a
liquid substrate where they self-assemble to give optical quality reflective
surfaces. Since liquid surfaces can be modified with a variety of means (e.g.
rotation, electromagnetic fields), this opens the possibility of making a new
class of versatile and inexpensive optical elements that can have complex
shapes which can be modified within short time scales. Interferometric
measurements show optical quality surfaces. We have obtained reflectivity
curves that show 80% peak reflectivities.We are confident that we can improve
the reflectivity curves, for theoretical models predict higher values. We
expect that nanoengineered liquid mirrors should be useful for scientific and
engineering applications. The technology is interesting for large optics, such
as large rotating parabolic mirrors, because of its low cost. Furthermore,
because the surfaces of ferrofluids can be shaped with magnetic fields, one can
generate complex, time varying surfaces difficult to make with conventional
techniques.


title:
Nearside-farside theory of differential cross sections : resummation of
  a partial wave series involving Legendre polynomials

abstract:
  We report a new resummation procedure for the partial wave series (PWS)
representation of the scattering amplitude, when a basis set of Legendre
polynomials is used for the expansion. The effect of the resummation is to
remove from the PWS the factor containing alpha and beta. The resummed
scattering amplitude is then exactly decomposed into the sum of a nearside (N)
subamplitude and a farside (F) subamplitude. We make two applications of the NF
resummed theory: to elastic angular scattering in a strongly absorptive
collision and to a state-to-state differential cross section for the I + HI >
IH + I reaction. In both applications, we can understand the physical origin of
structure in the angular scattering for suitable choices of alpha, beta and r.


title: Fractal Rigidity in Migraine

abstract:
  We study the middle cerebral artery blood flow velocity (MCAfv) in humans
using transcranial Doppler ultrasonography (TCD). Scaling properties of time
series of the axial flow velocity averaged over a cardiac beat interval may be
characterized by two exponents. The short time scaling exponent (STSE)
determines the statistical properties of fluctuations of blood flow velocities
in short-time intervals while the Hurst exponent describes the long-term
fractal properties. In many migraineurs the value of the STSE is significantly
reduced and may approach that of the Hurst exponent. This change in dynamical
properties reflects the significant loss of short-term adaptability and the
overall hyperexcitability of the underlying cerebral blood flow control system.
We call this effect fractal rigidity.


title:
Alkali and Alkaline Earth Metal Compounds: Core-Valence Basis Sets and
  Importance of Subvalence Correlation

abstract:
  Core-valence basis sets for the alkali and alkaline earth metals Li, Be, Na,
Mg, K, and Ca are proposed. The basis sets are validated by calculating
spectroscopic constants of a variety of diatomic molecules involving these
elements. Neglect of $(3s,3p)$ correlation in K and Ca compounds will lead to
erratic results at best, and chemically nonsensical ones if chalcogens or
halogens are present. The addition of low-exponent $p$ functions to the K and
Ca basis sets is essential for smooth convergence of molecular properties.
Inclusion of inner-shell correlation is important for accurate spectroscopic
constants and binding energies of all the compounds. In basis set
extrapolation/convergence calculations, the explicit inclusion of alkali and
alkaline earth metal subvalence correlation at all steps is essential for K and
Ca, strongly recommended for Na, and optional for Li and Mg, while in Be
compounds, an additive treatment in a separate `core correlation' step is
probably sufficient. Consideration of $(1s)$ inner-shell correlation energy in
first-row elements requires inclusion of $(2s,2p)$ `deep core' correlation
energy in K and Ca for consistency. The latter requires special CCV$n$Z `deep
core correlation' basis sets. For compounds involving Ca bound to
electronegative elements, additional $d$ functions in the basis set are
strongly recommended. For optimal basis set convergence in such cases, we
suggest the sequence CV(D+3d)Z, CV(T+2d)Z, CV(Q+$d$)Z, and CV5Z on calcium.


title: Scaling in Non-stationary time series I

abstract:
  Most data processing techniques, applied to biomedical and sociological time
series, are only valid for random fluctuations that are stationary in time.
Unfortunately, these data are often non stationary and the use of techniques of
analysis resting on the stationary assumption can produce a wrong information
on the scaling, and so on the complexity of the process under study. Herein, we
test and compare two techniques for removing the non-stationary influences from
computer generated time series, consisting of the superposition of a slow
signal and a random fluctuation. The former is based on the method of wavelet
decomposition, and the latter is a proposal of this paper, denoted by us as
step detrending technique. We focus our attention on two cases, when the slow
signal is a periodic function mimicking the influence of seasons, and when it
is an aperiodic signal mimicking the influence of a population change (increase
or decrease). For the purpose of computational simplicity the random
fluctuation is taken to be uncorrelated. However, the detrending techniques
here illustrated work also in the case when the random component is correlated.
This expectation is fully confirmed by the sociological applications made in
the companion paper. We also illustrate a new procedure to assess the existence
of a genuine scaling, based on the adoption of diffusion entropy, multiscaling
analysis and the direct assessment of scaling. Using artificial sequences, we
show that the joint use of all these techniques yield the detection of the real
scaling, and that this is independent of the technique used to detrend the
original signal.


title: Scaling in Non-stationary Time Series II: Teen Birth Phenomenon

abstract:
  This paper is devoted to the problem of statistical mechanics raised by the
analysis of an issue of sociological interest: the teen birth phenomenon. It is
expected that these data are characterized by correlated fluctuations,
reflecting the cooperative properties of the process. However, the assessment
of the anomalous scaling generated by these correlations is made difficult, and
ambiguous as well, by the non-stationary nature of the data that show a clear
dependence on seasonal periodicity (periodic component) and an average changing
slowly in time (slow component), as well. We use the detrending techniques
described in the companion paper \cite{paper1}, to safely remove all the biases
and to derive the genuine scaling of the teen birth phenomenon.


title: Depleted-Uranium Weapons: the Whys and Wherefores

abstract:
  The only military application in which depleted-uranium (DU) alloys
out-perform present-day tungsten alloys is long-rod penetration into a main
battle-tank's armor. However, this advantage is only on the order of 10%, and
it disappears when the comparison is made in terms of actual lethality of
complete anti-tank systems instead of laboratory-type steel penetration
capability. Therefore, new micro- and nano-engineered tungsten alloys may soon
out-perform DU alloys, enabling the production of tungsten munition which will
be better than existing uranium munition, and whose overall life-cycle cost
will be lower, due to the absence of the problems related to the radioactivity
of uranium. The reasons why DU weapons have been introduced and used are
analysed from the perspective that their radioactivity must have played an
important role in the decision making process. It is found that DU weapons
belong to the diffuse category of low-radiological-impact nuclear weapons to
which emerging types of low-yield (i.e., fourth generation) nuclear explosives
also belong. It is concluded that the battlefield use of DU during the 1991
Gulf War, which broke a 46-year-long taboo against the intentional use or
induction of radioactivity in combat, has created a military and legal
precedent which has trivialized the combat use of radioactive materials, and
therefore made the use of nuclear weapons more probable.


title: The spin of the mesons and baryons

abstract:
  It is shown that the spin of pi (0), eta, Lambda, Sigma (+,-,0), Xi (-,0),
Lambda-c (+), Sigma-c (0), Xi-c (0), and Omega-c (0) mesons and baryons can be
explained by the sum of the angular momentum vectors and spin vectors of the
electromagnetic waves which are in these particles according to the standing
wave model. The spin of the pi (+,-), K (+,-,0), D (+,-,0), and D-S (+,-)
mesons and of the neutron is the sum of the angular momentum vectors of the
oscillations and of the spin vectors of the neutrinos and the electric charges
which are in the cubic lattice of these particles. Spin 1/2 is the consequence
of the superposition of two perpendicular standing waves of equal frequencies
and amplitudes shifted in phase by pi/2. The spin of the antiparticles of the
mesons and baryons is the same as the spin of the ordinary particles.


title:
Metachronal wave and hydrodynamic interaction for deterministic
  switching rowers

abstract:
  We employ a model system, called rowers, as a generic physical framework to
define the problem of the coordinated motion of cilia (the metachronal wave) as
a far from equilibrium process. Rowers are active (two-state) oscillators
interacting solely through forces of hydrodynamic origin. In this work, we
consider the case of fully deterministic dynamics, find analytical solutions of
the equation of motion in the long wavelength (continuum) limit, and
investigate numerically the short wavelength limit. We prove the existence of
metachronal waves below a characteristic wavelength. Such waves are unstable
and become stable only if the sign of the coupling is reversed. We also find
that with normal hydrodynamic interaction the metachronal pattern has the form
of stable trains of traveling wave packets sustained by the onset of
anti-coordinated beating of consecutive rowers.


title:
Accurate and concise atomic CI via generalization of analytic Laguerre
  type orbitals and examples of ab-initio error estimation for excited states

abstract:
  We propose simple analytic, non-orthogonal but selectively orthogonalizable,
generalized Laguerre type atomic orbitals, providing clear physical
interpretation and near equivalent accuracy with numerical multi-configuration
self-consistent field, to atomic configuration interaction calculations. By
analyzing the general Eckart theorem we use their simple interpretation, via a
thorough investigation in orbital space, to estimate, for the first time (the
exact value being, or considered, unknown), an ab-initio energy uncertainty,
i.e. proximity to the exact energy, for several excited atomic states known to
have the danger to suffer from variational collapse.


title: Alternative model of propagation of spikes along neurons

abstract:
  Here a viable and never before investigated mechanism of propagation of
spikes along neurons is proposed. In the following, velocity of propagation of
small-amplitude pressure waves through the cytoplasmic interior of myelinated
and unmyelinated axons of different diameters is theoretically estimated, and
is found to generally agree with the action potential (AP) conduction
velocities. This remarkable coincidence allows to surmise a model in which AP
spread along axon is propelled not by straggling ionic currents as in the
widely accepted local circuit theory, but by mechanoactivation of the membrane
ion channels by a traveling pressure pulse. Hydraulic pulses propagating in the
viscous axoplasm are calculated to decay over $\sim$ 1 mm distances, and it is
further hypothesized that it is the role of influxing during the AP Ca$^{2+}$
ions to activate the membrane skeletal protein network for a brief radial
contraction amplifying the pressure pulse and preventing its decay. The model
correctly predicts that the AP conduction velocity should vary as the one-half
power of axon diameter for large unmyelinated axons, and as the first power of
the diameter for myelinated axons, provided that specific mechanical properties
of axons are independent from diameter; that myelinization increases the
conduction velocity; that the conduction velocity increases with the
temperature. Unlike the local circuit theory, the model is able to
qualitatively explain observed increase in the AP duration in axons of smaller
diameters. Predictions of...


title: Localized helium excitations in 4He_N-benzene clusters

abstract:
  We compute ground and excited state properties of small helium clusters 4He_N
containing a single benzene impurity molecule. Ground-state structures and
energies are obtained for N=1,2,3,14 from importance-sampled, rigid-body
diffusion Monte Carlo (DMC). Excited state energies due to helium vibrational
motion near the molecule surface are evaluated using the projection operator,
imaginary time spectral evolution (POITSE) method. We find excitation energies
of up to ~23 K above the ground state. These states all possess vibrational
character of helium atoms in a highly anisotropic potential due to the aromatic
molecule, and can be categorized in terms of localized and collective
vibrational modes. These results appear to provide precursors for a transition
from localized to collective helium excitations at molecular nanosubstrates of
increasing size. We discuss the implications of these results for analysis of
anomalous spectral features in recent spectroscopic studies of large aromatic
molecules in helium clusters.


title: Wavelet analysis of epileptic spikes

abstract:
  Interictal spikes and sharp waves in human EEG are characteristic signatures
of epilepsy. These potentials originate as a result of synchronous,
pathological discharge of many neurons. The reliable detection of such
potentials has been the long standing problem in EEG analysis, especially after
long-term monitoring became common in investigation of epileptic patients. The
traditional definition of a spike is based on its amplitude, duration,
sharpness, and emergence from its background. However, spike detection systems
built solely around this definition are not reliable due to the presence of
numerous transients and artifacts. We use wavelet transform to analyze the
properties of EEG manifestations of epilepsy. We demonstrate that the behavior
of wavelet transform of epileptic spikes across scales can constitute the
foundation of a relatively simple yet effective detection algorithm.


title:
Investigation of Self-Preservation Theory in Two Dimensional Turbulent
  Mixing Layers

abstract:
  The behavior of a two dimensional, steady turbulent mixing layer was
investigated. Besides the usual velocity components, all the contributing
components of the Reynolds Stresses are also calculated and presented. The
results indicated that in the two dimensional steady turbulent mixing layers
the theory of self-preservation is not valid for all the flow domain, and that
the flow is turbulent regime is divided into two areas. Through calculation of
Reynolds Stress components at the point of initiation of the flow, it was shown
that the turbulent flow in the area containing the point of singularity of the
flow is not, as previously believed, self-preserved.


title: Asymptotic Probability Density Function of Nonlinear Phase Noise

abstract:
  The asymptotic probability density function of nonlinear phase noise, often
called the Gordon-Mollenauer effect, is derived analytically when the number of
fiber spans is very large. The nonlinear phase noise is the summation of
infinitely many independently distributed noncentral chi-square random
variables with two degrees of freedom. The mean and standard deviation of those
random variables are both proportional to the square of the reciprocal of all
odd natural numbers. The nonlinear phase noise can also be accurately modeled
as the summation of a noncentral chi-square random variable with two degrees of
freedom and a Gaussian random variable.


title:
Optical properties of tungsten thin films perforated with a
  bidimensional array of subwavelength holes

abstract:
  We present a theorical investigation of the optical transmission of a
dielectric grating carved in a tungsten layer. For appropriate wavelengths
tungsten shows indeed a dielectric behaviour. Our numerical simulations leads
to theoretical results similar to those found with metallic systems studied in
earlier works. The interpretation of our results rests on the idea that the
transmission is correlated with the resonant response of eigenmodes coupled to
evanescent diffraction orders.