title:
The joint influence of topography and atmosphere on the meridional
  transport fluctuations in the Southern Ocean and its link with the ENSO
  events

abstract:
  This article deals with the investigation of the influence of topography and
coastlines on the dynamics of the depth averaged Antarctic Circumpolar Current
(ACC), driven by wind and atmospheric pressure. This is achieved with the help
of a global barotropic circulation model, under idealized and real atmospheric
conditions.
  It is shown that the variability of meridional mass fluxes due to the
atmospheric conditions over the ACC can induce short-period density anomalies
in the Southern Ocean to the north in the vicinity of 47S, which can be
transferred to low latitudes by the wave mechanism described by Ivchenko et al.
2004, that could have significance with respect to rapid extra-tropical oceanic
links. The results of the barotropic modeling demonstrate that changes in wind
strength over the ACC, together with the effect of bottom topography and
coastlines, induce some meridional flow variability in the Southern Ocean, and
this meridional flux variability in the Pacific Ocean is anticorrelated with
the strength of the wind over the ACC. The possible link between the short-term
variations of the meridional flux in the Pacific sector and the ENSO events
(Southern Oscillation) is discussed.


title: Structure of n-clique networks embedded in a complex network

abstract:
  We propose the n-clique network as a powerful tool for understanding global
structures of combined highly-interconnected subgraphs, and provide theoretical
predictions for statistical properties of the n-clique networks embedded in a
complex network using the degree distribution and the clustering spectrum.
Furthermore, using our theoretical predictions, we find that the statistical
properties are invariant between 3-clique networks and original networks for
several observable real-world networks with the scale-free connectivity and the
hierarchical modularity. The result implies that structural properties are
identical between the 3-clique networks and the original networks.


title:
The degenerate Fermi gas with renormalized density-dependent
  interactions in the K harmonic approximation

abstract:
  We present a simple implementation of a density-dependent, zero-range
interactions in a degenerate Fermi gas described in hyperspherical coordinates.
The method produces a 1D effective potential which accurately describes the
ground state energy as a function of the hyperradius, the rms radius of the two
spin component gas throughout the unitarity regime. In the unitarity regime the
breathing mode frequency is found to limit to the non-interacting value. A
dynamical instability, similar to the Bosenova, is predicted to be possible in
gases containing more than three spin components, for large, negative, two-body
scattering lengths.


title:
The Nylon Scintillator Containment Vessels for the Borexino Solar
  Neutrino Experiment

abstract:
  Borexino is a solar neutrino experiment designed to observe the 0.86 MeV Be-7
neutrinos emitted in the pp cycle of the sun. Neutrinos will be detected by
their elastic scattering on electrons in 100 tons of liquid scintillator. The
neutrino event rate in the scintillator is expected to be low (~0.35 events per
day per ton), and the signals will be at energies below 1.5 MeV, where
background from natural radioactivity is prominent. Scintillation light
produced by the recoil electrons is observed by an array of 2240
photomultiplier tubes. Because of the intrinsic radioactive contaminants in
these PMTs, the liquid scintillator is shielded from them by a thick barrier of
buffer fluid. A spherical vessel made of thin nylon film contains the
scintillator, separating it from the surrounding buffer. The buffer region
itself is divided into two concentric shells by a second nylon vessel in order
to prevent inward diffusion of radon atoms. The radioactive background
requirements for Borexino are challenging to meet, especially for the
scintillator and these nylon vessels. Besides meeting requirements for low
radioactivity, the nylon vessels must also satisfy requirements for mechanical,
optical, and chemical properties. The present paper describes the research and
development, construction, and installation of the nylon vessels for the
Borexino experiment.


title: Quantum mechanics and rational ignorance

abstract:
  In the present article we use the quantum formalism to describe the process
of choice under rational ignorance. We consider as a basic task a question or
an issue where the only answers are 0 and 1. We show that under rational
ignorance the opinion state of a person can be described as a qubit state. We
analyze the predictions that the quantum formalism give in the study of
rational ignorance. We find that answers to different uncorrelated questions
are contextual, that is they are influenced by the previous questions, even if
uncorrelated. Another interesting prediction is an uncertainty effect which
holds when we consider the statistical variance of two or more questions under
rational ignorance.


title:
An experimental study of intermodulation effects in an atomic fountain
  frequency standard

abstract:
  The short-term stability of passive atomic frequency standards, especially in
pulsed operation, is often limited by local oscillator noise via
intermodulation effects. We present an experimental demonstration of the
intermodulation effect on the frequency stability of a continuous atomic
fountain clock where, under normal operating conditions, it is usually too
small to observe. To achieve this, we deliberately degrade the phase stability
of the microwave field interrogating the clock transition. We measure the
frequency stability of the locked, commercial-grade local oscillator, for two
modulation schemes of the microwave field: square-wave phase modulation and
square-wave frequency modulation. We observe a degradation of the stability
whose dependence with the modulation frequency reproduces the theoretical
predictions for the intermodulation effect. In particular no observable
degradation occurs when this frequency equals the Ramsey linewidth.
Additionally we show that, without added phase noise, the frequency instability
presently equal to 2x10-13 at 1s, is limited by atomic shot-noise and therefore
could be reduced were the atomic flux increased.


title: FEM investigation of leaky modes in hollow core photonic crystal fibers

abstract:
  Hollow-core holey fibers are promising candidates for low-loss guidance of
light in various applications, e.g., for the use in laser guide star adaptive
optics systems in optical astronomy. We present an accurate and fast method for
the computation of light modes in arbitrarily shaped waveguides. Maxwell's
equations are discretized using vectorial finite elements (FEM). We discuss how
we utilize concepts like adaptive grid refinement, higher-order finite
elements, and transparent boundary conditions for the computation of leaky
modes in photonic crystal fibers. Further, we investigate the convergence
behavior of our methods. We employ our FEM solver to design hollow-core
photonic crystal fibers (HCPCF) whose cores are formed from 19 omitted cladding
unit cells. We optimize the fiber geometry for minimal attenuation using
multidimensional optimization taking into account radiation loss (leaky modes).


title: Nearfield Electromagnetic Effects on Einstein Special Relativity

abstract:
  In this paper Maxwell equations are used to analyze the propagation of
oscillating electric and magnetic fields from a moving electric dipole source.
The results show that both the magnetic field and electric fields generated
propagate faster than the speed of light in the nearfield and reduce to the
speed of light as they propagate into the farfield of the source. In addition,
the results show that the speed of the fields are dependant on the velocity of
the source in the nearfield and only become independent in the farfield. These
effects are shown to be the same whether the source or observation point is
moving. Because these effects conflict with the assumptions on which Einstein's
theory of special relativity theory is based, relativity theory is reanalyzed.
The analysis shows that the relativistic gamma factor is dependant on whether
the analysis is performed using nearfield or farfield propagating EM fields. In
the nearfield, gamma is approximately one indicating that the coordinate
transforms are Galilean in the nearfield. In the farfield the gamma factor
reduces to the standard known relativistic formula indicating that they are
approximately valid in the farfield. Because time dilation and space
contraction depend on whether nearfield or farfield propagating fields are used
in their analysis, it is proposed that Einstein relativistic effects are an
illusion created by the propagating EM fields used in their measurement.
Instead space and time are proposed to not be flexible as indicated by Galilean
relativity.


title: The modeling of the ENSO events with the help of a simple model

abstract:
  The Southern Oscillation (ENSO) is modelled with the help of a simple model
representing a classical damped oscillator forced by external forcing. Eastern
Pacific sea surface temperature (SST) and the mean equatorial Pacific
thermocline depth correspond to the roles of momentum and position. The
external forcing of the system is supplied by short-period meridional mass
fluctuations in the Pacific sector of the Southern Ocean due to the joint
effect of the atmospheric variability over the Antarctic Circumpolar Current
(ACC), bottom topography and coastlines, and also by the variability of
westerly winds in the tropics. Under such conditions the ENSO-like oscillations
arise as a result of propagation of signals due to both initial signals
appeared in the Southern Ocean and the tropical westerly wind anomaly, that
propagate then across the equatorial Pacific by means of fast wave processes.
The external forcings are the main factor in establishing the oscillation
pattern.


title: A Toy Model of the Rat Race

abstract:
  We introduce a toy model of the "rat race" in which individuals try to better
themselves relative to the rest of the population. An individual is
characterized by a real-valued fitness and each advances at a constant rate by
an amount that depends on its standing in the population. The leader advances
to remain ahead of its nearest neighbor, while all others advance by an amount
that is set by the distance to the leader. A rich dynamics occurs as a function
of the mean jump size of the trailing particles. For small jumps, the leader
maintains its position, while for large jumps, there are long periods of stasis
that are punctuated by episodes of explosive advancement and many lead changes.
Intermediate to these two regimes, agents reach a common fitness and evolution
grinds to a halt.

categories: physics.soc-ph cond-mat.stat-mech physics.gen-ph q-bio.PE


title:
Bosonic Helium droplets with cationic impurities: onset of
  electrostriction and snowball effects from quantum calculations

abstract:
  Variational MonteCarlo and Diffusion MonteCarlo calculations have been
carried out for cations like Li$^+$, Na$^+$ and K$^+$ as dopants of small
helium clusters over a range of cluster sizes up to about 12 solvent atoms. The
interaction has been modelled through a sum-of-potential picture that
disregards higher order effects beyond atom-atom and atom-ion contributions.
The latter were obtained from highly correlated ab-initio calculations over a
broad range of interatomic distances.
  This study focuses on two of the most striking features of the microsolvation
in a quantum solvent of a cationic dopant: electrostriction and snowball
effects. They are here discussed in detail and in relation with the nanoscopic
properties of the interaction forces at play within a fully quantum picture of
the clusters features.


title:
Analyzing the House Fly's Exploratory Behavior with Autoregression
  Methods

abstract:
  This paper presents a detailed characterization of the trajectory of a single
housefly with free range of a square cage. The trajectory of the fly was
recorded and transformed into a time series, which was fully analyzed using an
autoregressive model, which describes a stationary time series by a linear
regression of prior state values with the white noise. The main discovery was
that the fly switched styles of motion from a low dimensional regular pattern
to a higher dimensional disordered pattern. This discovered exploratory
behavior is, irrespective of the presence of food, characterized by anomalous
diffusion.


title: Event Reconstruction with MarlinReco at the ILC

abstract:
  After an overview of the modular analysis and reconstruction framework Marlin
an introduction on the functionality of the Marlin-based reconstruction package
MarlinReco is given. This package includes a full set of modules for event
reconstruction based on the Particle Flow approach. The status of the software
is reviewed and recent results using this software package for event
reconstruction are presented.


title: Cosmic Contact Censorship

abstract:
  Till date we have not made Contact with any Extraterrestrial civilizations.
The Fermi Paradox remains a paradox - the Great Silence prevails. In the light
of the Rare Earth hypothesis, it seems that advanced life is exceedingly rare
in the universe. Also, if there does exist some Extraterrestrial civilizations
then still achieving Contact is extremely difficult as the very nature of the
universe discourages Contact. It's as if there is a Cosmic Contact Censorship
in place.


title: Self-Organized Network Flows

abstract:
  A model for traffic flow in street networks or material flows in supply
networks is presented, that takes into account the conservation of cars or
materials and other significant features of traffic flows such as jam
formation, spillovers, and load-dependent transportation times. Furthermore,
conflicts or coordination problems of intersecting or merging flows are
considered as well. Making assumptions regarding the permeability of the
intersection as a function of the conflicting flows and the queue lengths, we
find self-organized oscillations in the flows similar to the operation of
traffic lights.


title: A particular case of a Lifting Hele-Shaw Cell

abstract:
  We present a very simple method of obtaining spectacular fractals, using a
particular case of a lifting Hele-Shaw cell.


title:
Integral Equation for Scattering of Light by a Strong Magnetostatic
  Field in Vacuum

abstract:
  When a strong magnetostatic field is present, vacuum effectively appears as a
linear, uniaxial, dielectric-magnetic medium for small-magnitude optical
fields. The availability of the frequency-domain dyadic Green function when the
magnetostatic field is spatially uniform facilitates the formulation of an
integral equation for the scattering of an optical field by a spatially varying
magnetostatic field in vacuum. This integral equation can be numerically
treated by using the method of moments as well as the coupled dipole method.
Furthermore, the principle underlying the strong-property-fluctuation theory
allows the homogenization of a spatially varying magnetostatic field in the
context of light scattering.


title:
Liquid-infiltrated photonic crystals: Ohmic dissipation and broadening
  of modes

abstract:
  The pronounced light-matter interactions in photonic crystals make them
interesting as opto-fludic "building blocks" for lab-on-a-chip applications. We
show how conducting electrolytes cause dissipation and smearing of the
density-of-states, thus altering decay dynamics of excited bio-molecules
dissolved in the electrolyte. Likewise, we find spatial damping of propagating
modes, of the order dB/cm, for naturally occurring electrolytes such as
drinking water or physiological salt water.


title:
Generation and Observation of Coherent, Long--Lived Structures in a
  Laser--Plasma Channel

abstract:
  In recent experiments of laser pulse interaction at relativistic intensities
with a low density plasma, the proton radiography technique showed evidence of
long--lived field structures generated after the self-channeling of the laser
pulse. We present 2D particle-in-cell simulations of this interaction regime,
where the dynamics of similar structures has been resolved with high temporal
and spatial resolution. An axially symmetrical field pattern, resembling both
soliton-like and vortex structures, has been observed. A study of the physics
of such structures and a comparison with experimental data is in progress.


title:
Fantappi\'e-Arcidiacono theory of relativity versus recent cosmological
  evidences : a preliminary comparison

abstract:
  Notwithstanding the Fantappie-Arcidiacono theory of relativity was introduced
more than half a century ago, its observational confirmations in cosmology (the
only research field where its predictions differ from those of the Einsteinian
relativity) are still missing. In line of principle, this theory may be
proposed as a valid alternative to the current views assuming the dominance of
dark matter and inflationary scenarios. In this work, the relativistic
transformation of the Poynting vector associated with the reception of
electromagnetic waves emitted by astronomical obiects is derived in the context
of the special version of the theory. On the basis of this result, and some
heuristic assumptions, two recent collections of observational data are
analyzed.


title: Majorana and the quasi-stationary states in Nuclear Physics

abstract:
  A complete theoretical model describing artificial disintegration of nuclei
by bombardment with alpha-particles, developed by Majorana as early as in 1930,
is discussed in detail alongside the basic experimental evidences that
motivated it. By following the quantum dynamics of a state resulting from the
superposition of a discrete state with a continuum one, whose interaction is
described by a given potential term, Majorana obtained (among the other
predictions) the explicit expression for the integrated cross section of the
nuclear process, which is the direct measurable quantity of interest in the
experiments. Though this is the first application of the concept of
quasi-stationary states to a Nuclear Physics problem, it seems also that the
unpublished Majorana's work anticipates by several years the related seminal
paper by Fano on Atomic Physics.

categories: physics.hist-ph hep-ph nucl-th physics.atom-ph


title:
Exploring DNA translocation through a nanopore via a multiscale
  Lattice-Boltzmann Molecular-Dynamics methodology

abstract:
  A multiscale approach is used to simulate the translocation of DNA through a
nanopore. Within this scheme, the interactions of the molecule with the
surrounding fluid (solvent) are explicitly taken into account. By generating
polymers of various initial configurations and lengths we map the probability
distibutions of the passage times of the DNA through the nanopore. A scaling
law behavior for the most probable of these times with respect to length is
derived, and shown to exhibit an exponent that is in a good agreement with the
experimental findings. The essential features of the DNA dynamics as it passes
through the pore are explored.


title: Building CMS Pixel Barrel Detectur Modules

abstract:
  For the barrel part of the CMS pixel tracker about 800 silicon pixel detector
modules are required. The modules are bump bonded, assembled and tested at the
Paul Scherrer Institute. This article describes the experience acquired during
the assembly of the first ~200 modules.


title: CMS Barrel Pixel Detector Overview

abstract:
  The pixel detector is the innermost tracking device of the CMS experiment at
the LHC. It is built from two independent sub devices, the pixel barrel and the
end disks. The barrel consists of three concentric layers around the beam pipe
with mean radii of 4.4, 7.3 and 10.2 cm. There are two end disks on each side
of the interaction point at 34.5 cm and 46.5 cm. This article gives an overview
of the pixel barrel detector, its mechanical support structure, electronics
components, services and its expected performance.


title: Radiation induced force between two planar waveguides

abstract:
  We study the electromagnetic force exerted on a pair of parallel slab
waveguides by the light propagating through them. We have calculated the
dependence of the force on the slab separation by means of the Maxwell--Stress
tensor formalism and we have discussed its main features for the different
propagation modes: spatially symmetric (antisymmetric) modes give rise to an
attractive (repulsive) interaction. We have derived the asymptotic behaviors of
the force at small and large separation and we have quantitatively estimated
the mechanical deflection induced on a realistic air-bridge structure.


title:
A study of H+H$_2$ and several H-bonded molecules by phaseless
  auxiliary-field quantum Monte Carlo with planewave and Gaussian basis sets

abstract:
  We present phaseless auxiliary-field (AF) quantum Monte Carlo (QMC)
calculations of the ground states of some hydrogen-bonded systems. These
systems were selected to test and benchmark different aspects of the new
phaseless AF QMC method. They include the transition state of H+H$_2$ near the
equilibrium geometry and in the van der Walls limit, as well as H$_2$O, OH, and
H$_2$O$_2$ molecules. Most of these systems present significant challenges for
traditional independent-particle electronic structure approaches, and many also
have exact results available. The phaseless AF QMC method is used either with a
planewave basis with pseudopotentials or with all-electron Gaussian basis sets.
For some systems, calculations are done with both to compare and characterize
the performance of AF QMC under different basis sets and different
Hubbard-Stratonovich decompositions. Excellent results are obtained using as
input single Slater determinant wave functions taken from independent-particle
calculations. Comparisons of the Gaussian based AF QMC results with exact full
configuration show that the errors from controlling the phase problem with the
phaseless approximation are small. At the large basis-size limit, the AF QMC
results using both types of basis sets are in good agreement with each other
and with experimental values.


title:
Yet on statistical properties of traded volume: correlation and mutual
  information at different value magnitudes

abstract:
  In this article we analyse linear correlation and non-linear dependence of
traded volume, $v$, of the 30 constituents of Dow Jones Industrial Average at
different value scales. Specifically, we have raised $v$ to some real value
$\alpha $ or $\beta $, which introduces a bias for small ($ \alpha, \beta <0$)
or large ($\alpha, \beta >1$) values. Our results show that small values of $v$
are regularly \emph{anti-correlated} with values at other scales of traded
volume. This is consistent with the high liquidity of the 30 equities analysed
and the asymmetric form of the multi-fractal spectrum for traded volume which
has supported the dynamical scenario presented by us.


title: Peer Instruction: Comparing Clickers to Flashcards

abstract:
  Peer Instruction (PI) is a student-centered instructional approach developed
at Harvard by Eric Mazur (1997). The method has been welcomed by the science
community and adopted by a large number of colleges and universities, due among
other reasons to its common sense approach and its documented effectiveness. In
PI, the progression of any given class depends on the outcome of real-time
student feedback to ConcepTests: multiple-choice conceptual questions. In the
early 1990s, students responded to ConcepTests using flashcards showing their
answer. Instructors would then estimate the proportion of students holding each
alternative conception. A few years later Mazur began using wireless handheld
devices - colloquially called clickers- to replace the flashcards. Previous
users of clickers in university classrooms had reported benefits such as
increased rates of attendance and decreased rates of attrition (Owens et al.,
2004; Lopez-Herrejon & Schulman, 2004). This paper empirically measures the
specific contribution of clickers to conceptual learning and traditional
problem solving skills as compared to low-budget flashcards. Results show that
clickers do not provide any learning advantage when compared to flashcards.
Nevertheless, clickers offer many advantages from a teaching perspective which
should be considered.


title: Method of reconstructing a moving pulse

abstract:
  We present a method of analyzing a set of N time signals f_i(t) that consist
of local measurements of the same physical observable taken at N sequential
locations Z_i along the length of an experimental device. The result is an
algorithm for reconstructing an approximation F(z,t) of the field f(z,t) in the
inaccessible regions between the points of measurement. We also explore the
conditions needed for this approximation to hold, and test the algorithm under
a variety of conditions. We apply this method to analyze the magnetic field
measurements taken on the Compact Toroid Injection eXperiment (CTIX) plasma
accelerator; providing a direct means of visualizing experimental data,
quantifying global properties, and benchmarking simulation.


title: The X-ray Telescope of CAST

abstract:
  The Cern Axion Solar Telescope (CAST) is in operation and taking data since
2003. The main objective of the CAST experiment is to search for a hypothetical
pseudoscalar boson, the axion, which might be produced in the core of the sun.
The basic physics process CAST is based on is the time inverted Primakoff
effect, by which an axion can be converted into a detectable photon in an
external electromagnetic field. The resulting X-ray photons are expected to be
thermally distributed between 1 and 7 keV. The most sensitive detector system
of CAST is a pn-CCD detector combined with a Wolter I type X-ray mirror system.
With the X-ray telescope of CAST a background reduction of more than 2 orders
off magnitude is achieved, such that for the first time the axion photon
coupling constant g_agg can be probed beyond the best astrophysical constraints
g_agg < 1 x 10^-10 GeV^-1.


title: The CAST Time Projection Chamber

abstract:
  One of the three X-ray detectors of the CAST experiment searching for solar
axions is a Time Projection Chamber (TPC) with a multi-wire proportional
counter (MWPC) as a readout structure. Its design has been optimized to provide
high sensitivity to the detection of the low intensity X-ray signal expected in
the CAST experiment. A low hardware threshold of 0.8 keV is safely set during
normal data taking periods, and the overall efficiency for the detection of
photons coming from conversion of solar axions is 62 %. Shielding has been
installed around the detector, lowering the background level to 4.10 x 10^-5
counts/cm^2/s/keV between 1 and 10 keV. During phase I of the CAST experiment
the TPC has provided robust and stable operation, thus contributing with a
competitive result to the overall CAST limit on axion-photon coupling and mass.


title: The Micromegas detector of the CAST experiment

abstract:
  A low background Micromegas detector has been operating in the CAST
experiment at CERN for the search of solar axions during the first phase of the
experiment (2002-2004). The detector, made out of low radioactivity materials,
operated efficiently and achieved a very low level of background rejection (5 x
10^-5 counts/keV/cm^2/s) without shielding.


title:
A simple derivation of the Lorentz transformation and of the related
  velocity and acceleration formulae

abstract:
  The Lorentz transformation is entirely derived from length contraction,
itself established through the known light-clock thought experiment . This
makes the derivation accessible to beginning students once Eintein's two
postulates have been admitted. The formula derived for the space part of the
general rotation-free Lorentz transformation is very compact and allows for an
easy derivation of the velocity and acceleration transformations. A possibly
new and very simple relation is found between proper acceleration and
acceleration in an inertial frame.


title:
Ionization of Sodium and Rubidium nS, nP and nD Rydberg atoms by
  blackbody radiation

abstract:
  Results of theoretical calculations of ionization rates of Rb and Na Rydberg
atoms by blackbody radiation (BBR) are presented. Calculations have been
performed for nS, nP and nD states of Na and Rb, which are commonly used in a
variety of experiments, at principal quantum numbers n=8-65 and at three
ambient temperatures of 77, 300 and 600 K. A peculiarity of our calculations is
that we take into account the contributions of BBR-induced redistribution of
population between Rydberg states prior to photoionization and field ionization
by extraction electric field pulses. The obtained results show that these
phenomena affect both the magnitude of measured ionization rates and shapes of
their dependencies on n. The calculated ionization rates are compared with the
results of our earlier measurements of BBR-induced ionization rates of Na nS
and nD Rydberg states with n=8-20 at 300 K. A good agreement for all states
except nS with n>15 is observed. We also present the useful analytical formulae
for quick estimation of BBR ionization rates of Rydberg atoms.

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


title: Low pT Hadronic Physics with CMS

abstract:
  The pixel detector of CMS can be used to reconstruct very low pT charged
particles down to about 0.1 GeV/c. This can be achieved with high efficiency,
good resolution and a negligible fake rate for elementary collisions. In the
case of central PbPb collisions the fake rate can be kept low for pT > 0.4
GeV/c. In addition, the detector can be employed for identification of neutral
hadrons (V0s) and converted photons.


title: Traffic phenomena in biology: from molecular motors to organisms

abstract:
  Traffic-like collective movements are observed at almost all levels of
biological systems. Molecular motor proteins like, for example, kinesin and
dynein, which are the vehicles of almost all intra-cellular transport in
eukayotic cells, sometimes encounter traffic jam that manifests as a disease of
the organism. Similarly, traffic jam of collagenase MMP-1, which moves on the
collagen fibrils of the extracellular matrix of vertebrates, has also been
observed in recent experiments. Traffic-like movements of social insects like
ants and termites on trails are, perhaps, more familiar in our everyday life.
Experimental, theoretical and computational investigations in the last few
years have led to a deeper understanding of the generic or common physical
principles involved in these phenomena. In particular, some of the methods of
non-equilibrium statistical mechanics, pioneered almost a hundred years ago by
Einstein, Langevin and others, turned out to be powerful theoretical tools for
quantitative analysis of models of these traffic-like collective phenomena as
these systems are intrinsically far from equilibrium. In this review we
critically examine the current status of our understanding, expose the
limitations of the existing methods, mention open challenging questions and
speculate on the possible future directions of research in this
interdisciplinary area where physics meets not only chemistry and biology but
also (nano-)technology.


title: Two-pulse interference and superluminality

abstract:
  We examine how the interference of a coherent light-pulse with its slightly
time-delayed copy may generate a pulse nearly identical to the original one and
ahead of it. The simplicity of this 2-pulse system enabled us to obtain exact
analytic expressions of the pulse distortion, valid for a wide class of pulse
shapes. Explicit results are given for the pulses usually considered (gaussian,
hyperbolic secant) but also for more realistic pulses of strictly limited
duration. We finally show that the efficiency of the 2-pulse system is
comparable to that of the other superluminal systems, at least for the pulse
advancements actually demonstrated in the optical experiments.


title: A study of the Navier-Stokes-alpha model for two-dimensional turbulence

abstract:
  For wavenumbers k such that k * alpha > 1, corresponding to spatial scales
smaller than alpha, there are three candidate power laws for the energy
spectrum of the Navier-Stokes-alpha model, corresponding to three possible
dynamical eddy turnover time scales in the model equations: one from the
smoothed field, the second from the rough field and the third from a special
combination of the two. Using two-dimensional turbulence as a test case, we
measure the scaling of the spectra from high-resolution simulations of the
Navier-Stokes-alpha model, in the limit as alpha goes to infinity. We show that
the energy spectrum of the smoothed velocity field scales as k^{-7} in the
direct enstrophy cascade regime, consistent with dynamics dominated by the time
scale of the rough velocity field.


title: Cable dynamics applied to long-length scale mechanics of DNA

abstract:
  This paper introduces the use of cable dynamics models as a means to explore
the mechanics of DNA on long-length scales. It is on these length scales that
DNA forms twisted and curved three-dimensional shapes known as supercoils and
loops. These long-length scale DNA structures have a pronounced influence on
the functions of this molecule within the cell including the packing of DNA in
the cell nucleus, transcription, replication and gene repair. We provide a
short background to the mechanics of DNA and suggest the logical connection to
the mechanics of a low tension cable. A computational model is then summarized
and example results are presented for DNA supercoiling and looping.


title: Writhing Dynamics of Cables with Self-contact

abstract:
  Marine cables under low tension and torsion on the sea floor can form highly
contorted three-dimensional geometries that include loops (e.g. hockles) and
tangles. These geometries arise from the conversion of torsional strain energy
to bending strain energy or, kinematically, a conversion of twist to writhe. A
dynamic form of Kirchhoff rod theory is reviewed herein that captures these
nonlinear dynamic processes. The resulting theory is discretized using the
generalized-alpha method for finite differencing in both space and time.
Numerical solutions are presented for an example system of a cable subjected to
increasing twist at one end. The solutions show the dynamic evolution of the
cable from an initially straight element, through a buckled element in the
approximate form of a helix, through the dynamic collapse of this helix into a
loop, and subsequent intertwining of the loop with multiple sites of
self-contact.


title: Vortex flow generated by a magnetic stirrer

abstract:
  We investigate the flow generated by a magnetic stirrer in cylindrical
containers by optical observations, PIV measurements and particle and dye
tracking methods. The tangential flow is that of an ideal vortex outside of a
core, but inside downwelling occur with a strong jet in the very middle. In the
core region dye patterns remain visible over minutes indicating a pure stirring
and mixing property in this region. The results of quantitative measurements
can be described by simple formulas in the investigated region of the stirring
bar's rotation frequency. The tangential flow turns out to be dynamically
similar to that of big atmospheric vortices like dust devils and tornadoes.


title: Structural Modeling of DNA Loops in Lactose-Repressor

abstract:
  It is well known that the structural deformations (stressed states) of DNA
molecule play a crucial role in its biological functions including gene
expression. For instance, looping in DNA (often mediated by protein binding) is
a crucial step in many gene regulatory mechanisms. We use the mechanical rod
model of DNA molecules to simulate its structural interactions with proteins
(enzymes) during gene expression. Our rod model can simulate the nonlinear
dynamics of loop and supercoil formation in DNA on long length scales. The
formulation accounts for the structural stiffness of the DNA strand, its
intrinsic curvature, chiral (right-handed helical) construction and its
physical interactions with the surrounding medium. The simulations of
protein-mediated DNA looping illustrate how the mechanical properties of DNA
may affect the chemical kinetics of DNA-protein interactions and thereby
regulate gene expression.


title: Nonlinear dynamic strand model with coupled tension and torsion

abstract:
  We simulate the nonlinear dynamic responses in Kirchhoff rod by including the
important effects due to inertia and kinematic coupling of tension and torsion.
We begin by reviewing a dynamic rod model of a strand (length of cable or DNA)
in the form of a 12th order partial differential equation system. Numerical
solutions reveal the effects of dynamics on clamped strands due to slow
movements of their ends. We note that inertia plays a critical role in this
process, particularly under loading conditions that pass through an
instability. For example, we simulated a dynamic trasition path between two
possible equilibria of a clamped rod subject to very slow compression.


title: A novel approach to study realistic navigations on networks

abstract:
  We consider navigation or search schemes on networks which are realistic in
the sense that not all search chains can be completed. We show that the
quantity $\mu = \rho/s_d$, where $s_d$ is the average dynamic shortest distance
and $\rho$ the success rate of completion of a search, is a consistent measure
for the quality of a search strategy. Taking the example of realistic searches
on scale-free networks, we find that $\mu$ scales with the system size $N$ as
$N^{-\delta}$, where $\delta $ decreases as the searching strategy is improved.
  This measure is also shown to be sensitive to the distintinguishing
characteristics of networks. In this new approach, a dynamic small world (DSW)
effect is said to exist when $\delta \approx 0$. We show that such a DSW indeed
exists in social networks in which the linking probability is dependent on
social distances.


title:
A Riemannian geometrical method to classify tearing instabilities in
  plasmas

abstract:
  Riemannian geometrical tools, such as Ricci collineations and Killing
symmetries, so often used in Einstein general theory of gravitation are here
applied to plasma physics to build magnetic surfaces from Einstein plasma
metrics used in tokamak devices. It is shown that the Killing symmetries are
constrains the Einstein magnetic surfaces while the Killing vectors are built
in terms of the displacement of the toroidal surface. The pressure is computed
by applying these constraints to the pressure equations in tokamaks. A method,
based on the sign of the only nontrivial constant Riemann curvature component,
is suggested to classify tearing instability. Throughout the computations two
approximations are considered: The first is the small toroidality and the other
is the small displacement of the magnetic surfaces as Einstein spaces.

categories: physics.plasm-ph gr-qc math.DG physics.flu-dyn


title:
The high-density limit of two-electron systems: Results from the
  extended Overhauser approach

abstract:
  The ``extended Overhauser model'' [Overhauser, Can. J. Phys. 1995, 73, 683]
for the calculation of the spherically and system-averaged pair density (APD)
has been recently combined with the Kohn-Sham equations to yield realistic APD
and correlation energies. In this work we test this approach in the
high-density (weakly-correlated) limit of the He isoelectronic series and of
the Hooke's atom isoelectronic series. Unlike many of the commonly used energy
functionals, the Overhauser approach yields accurate correlation energies for
both series.


title:
QED calculation of the 2p3/2-2p1/2 transition energy in five-electron
  ion of argon

abstract:
  We perform ab initio QED calculation of the (1s)^2(2s)^22p_{3/2} -
(1s)^2(2s)^22p_{1/2} transition energy in the five-electron ion of argon. The
calculation is carried out by perturbation theory starting with an effective
screening potential approximation. Four different types of the screening
potentials are considered. The rigorous QED calculations of the two
lowest-order QED and electron-correlation effects are combined with approximate
evaluations of the third- and higher-order electron-correlation contributions.
The theoretical value for the wavelength obtained amounts to 441.261(70) (nm,
air) and perfectly agrees with the experimental one, 441.2559(1) (nm, air).


title: Cosmic Contact : To Be, or Not To Be Archimedean ?

abstract:
  This is a two part paper which discusses various issues of cosmic contact
related to what so far appears to be a self-imposed censorship implied by the
customary acceptance of the Archimedean assumption on space-time.


title:
Bandwidth control of forbidden transmission gaps in compound structures
  with subwavelength slits

abstract:
  Phase resonances in transmission compound structures with subwavelength slits
produce sharp dips in the transmission response. For all equal slits, the
wavelengths of these sharp transmission minima can be varied by changing the
width or the length of all the slits. In this paper we show that the width of
the dip, i.e., the frequency range of minimum transmittance, can be controlled
by making at least one slit different from the rest within a compound unit
cell. In particular, we investigate the effect that a change in the dielectric
filling, or in the length of a single slit produces in the transmission
response. We also analyze the scan angle behavior of these structures by means
of band diagrams, and compare them with previous results for all-equal slit
structures.


title: Oscillation and levitation of balls in continuously stratified fluids

abstract:
  The free motion of balls is investigated experimentally in continously
stratified fluid in a finite container. The oscillation frequency is found to
be very close to the local Brunt-Vaisala frequency. The effect of added mass
proves to be practically negligible. The evolution of rear jets is
demonstrated, and a kind of long term levitation is found. We show that the
classical viscous drag would lead to a much stronger damping than observed in
the experiment. This is interpreted as a consequence of the feedback from the
previously excited internal waves following their reflection from the
boundaries. A phenomenological equation with a modified drag term is proposed
to obtain a qualitative agreement with the observations. We point out that the
inclusion of a history term would lead further away from the observed data.


title: The unique chemical reactivity of a graphene nanoribbon's zigzag edge

abstract:
  The zigzag edge of a graphene nanoribbon possesses a unique electronic state
that is near the Fermi level and localized at the edge carbon atoms. We
investigate the chemical reactivity of these zigzag edge sites by examining
their reaction energetics with common radicals from first principles. A
"partial radical" concept for the edge carbon atoms is introduced to
characterize their chemical reactivity, and the validity of this concept is
verified by comparing the dissociation energies of edge-radical bonds with
similar bonds in molecules. In addition, the uniqueness of the zigzag-edged
graphene nanoribbon is further demonstrated by comparing it with other forms of
sp2 carbons, including a graphene sheet, nanotubes, and an armchair-edged
graphene nanoribbon.


title:
The tick-by-tick dynamical consistency of price impact in limit order
  books

abstract:
  Constant price impact functions, much used in financial literature, are shown
to give rise to paradoxical outcomes since they do not allow for proper
predictability removal: for instance the exploitation of a single large trade
whose size and time of execution are known in advance to some insider leaves
the arbitrage opportunity unchanged, which allows arbitrage exploitation
multiple times. We argue that chain arbitrage exploitation should not exist,
which provides an a contrario consistency criterion. Remarkably, all the stocks
investigated in Paris Stock Exchange have dynamically consistent price impact
functions. Both the bid-ask spread and the feedback of sequential same-side
market orders onto both sides of the order book are essential to ensure
consistency at the smallest time scale.


title: Scaling of Huygens-front speedup in weakly random media

abstract:
  Front propagation described by Huygens' principle is a fundamental mechanism
of spatial spreading of a property or an effect, occurring in optics,
acoustics, ecology and combustion. If the local front speed varies randomly due
to inhomogeneity or motion of the medium (as in turbulent premixed combustion),
then the front wrinkles and its overall passage rate (turbulent burning
velocity) increases. The calculation of this speedup is subtle because it
involves the minimum-time propagation trajectory. Here we show mathematically
that for a medium with weak isotropic random fluctuations, under mild
conditions on its spatial structure, the speedup scales with the 4/3 power of
the fluctuation amplitude. This result, which verifies a previous conjecture
while clarifying its scope, is obtained by reducing the propagation problem to
the inviscid Burgers equation with white-in-time forcing. Consequently,
field-theoretic analyses of the Burgers equation have significant implications
for fronts in random media, even beyond the weak-fluctuation limit.


title:
Theory and Applications of Infinitesimal Dipole Models for Computational
  Electromagnetics

abstract:
  The recently introduced quantum particle swarm optimization (QPSO) algorithm
is employed to find infinitesimal dipole models (IDM) for antennas with known
near-fields (measured or computed). The IDM can predict accurately both the
near-fields and the far- fields of the antenna. A theory is developed to
explain the mechanism behind the IDM using the multipole expansion method. The
IDM obtained from single frequency solutions is extrapolated over a frequency
range around the design frequency. The method is demonstrated by analyzing
conductingand dielectric- type antennas. A calibration procedure is proposed to
systematically implement infinitesimal dipoles within existing MOM codes. The
interaction of the IDM with passive and active objects is studied through
several examples. The IDM proved to predict the interaction efficiently. A
closed-form expression for the mutual admittance between similar or dissimilar
antennas, with arbitrary orientations and/or locations, is derived using the
reaction theorem.


title:
Particle-Particle, Particle-Scaling function (P3S) algorithm for
  electrostatic problems in free boundary conditions

abstract:
  An algorithm for fast calculation of the Coulombic forces and energies of
point particles with free boundary conditions is proposed. Its calculation time
scales as N log N for N particles. This novel method has lower crossover point
with the full O(N^2) direct summation than the Fast Multipole Method. The
forces obtained by our algorithm are analytical derivatives of the energy which
guarantees energy conservation during a molecular dynamics simulation. Our
algorithm is very simple. An MPI parallelised version of the code can be
downloaded under the GNU General Public License from the website of our group.


title: Quantum Particle Swarm Optimization for Electromagnetics

abstract:
  A new particle swarm optimization (PSO) technique for electromagnetic
applications is proposed. The method is based on quantum mechanics rather than
the Newtonian rules assumed in all previous versions of PSO, which we refer to
as classical PSO. A general procedure is suggested to derive many different
versions of the quantum PSO algorithm (QPSO). The QPSO is applied first to
linear array antenna synthesis, which is one of the standard problems used by
antenna engineers. The performance of the QPSO is compared against an improved
version of the classical PSO. The new algorithm outperforms the classical one
most of the time in convergence speed and achieves better levels for the cost
function. As another application, the algorithm is used to find a set of
infinitesimal dipoles that produces the same near and far fields of a circular
dielectric resonator antenna (DRA). In addition, the QPSO method is employed to
find an equivalent circuit model for the DRA that can be used to predict some
interesting parameters like the Q-factor. The QPSO contains only one control
parameter that can be tuned easily by trial and error or by suggested simple
linear variation. Based on our understanding of the physical background of the
method, various explanations of the theoretical aspects of the algorithm are
presented.


title: Observation of Kinetic Plasma Jets

abstract:
  Under certain conditions an intense kinetic plasma jet is observed to emerge
from the apex of laboratory simulations of coronal plasma loops. Analytic and
numerical models show that these jets result from a particle orbit instability
in a helical magnetic field whereby magnetic forces radially eject rather than
confine ions with sufficiently large counter-current axial velocity.


title: Strongly Correlated Photons in a Photonic Crystal

abstract: This paper is withdrawn.


title:
How potentials in different gauges yield the same retarded electric and
  magnetic fields

abstract:
  This paper presents a simple and systematic method to show how the potentials
in the Lorentz, Coulomb, Kirchhoff, velocity and temporal gauges yield the same
retarded electric and magnetic fields. The method appropriately uses the
dynamical equations for the scalar and vector potentials to obtain two wave
equations, whose retarded solutions lead to the electric and magnetic fields.
The advantage of this method is that it does not use explicit expressions for
the potentials in the above gauges, which are generally simple to obtain for
the scalar potential but generally difficult to calculate for the vector
potential. The spurious character of the term generated by the scalar potential
in the Coulomb, Kirchhoff and velocity gauges is noted. The non spurious
character of the term generated by the scalar potential in the Lorenz gauge is
emphasized.


title:
Comment on 'Helmholtz theorem and the v-gauge in the problem of
  superluminal and instantaneous signals in classical electrodynamics,' by
  Chubykalo et al [Found. of Phys. Lett, 19, 37-46 (2006)]

abstract:
  Fundamental errors in the Chubykalo et al paper [Found. of Phys. Lett, 19,
37-46 (2006)] are highlighted. Contrary to their claim that "... the
irrotational component of the electric field has a physical meaning and can
propagate exclusively instantaneously," it is shown that this instantaneous
component is physically irrelevant because it is always canceled by a term
contained into the solenoidal component. This result follows directly from the
solution of the wave equation that satisfies the solenoidal component.
Therefore the subsequent inference of these authors that there are two
mechanisms of transmission of energy and momentum in classical electrodynamics,
one retarded and the other one instantaneous, has no basis. The example given
by these authors in which the full electric field of an oscillating charge
equals its instantaneous irrotational component on the axis of oscillations is
proved to be false.


title: Transitions in the wake of a flapping foil

abstract:
  We study experimentally the vortex streets produced by a flapping foil in a
hydrodynamic tunnel, using 2D Particle Image Velocimetry (PIV). An analysis in
terms of a flapping frequency-amplitude phase space allows to identify: 1) the
transition from the well-known B\'enard-von K\'arm\'an (BvK) wake to the
reverse BvK vortex street that characterizes propulsive wakes, and 2) the
symmetry breaking of this reverse BvK pattern giving rise to an asymmetric
wake. We also show that the transition from a BvK wake to a reverse BvK wake
precedes the actual drag-thrust transition and we discuss the significance of
the present results in the analysis of flapping systems in nature.


title:
Path integral formulation for quantum nonadiabatic dynamics and the
  mixed quantum-classical limit

abstract:
  This work identifies geometric effects on dynamics due to nonadiabatic
couplings in Born Oppenheimer systems and provides a systematic method for
deriving corrections to mixed quantum-classical methods. Specifically, an exact
path integral formulation of the quantum nonadiabatic dynamics of Born
Oppenheimer systems is described. Stationary phase approximations to the
propagator for full quantum dynamics are derived. It is shown that quantum
corrections to mixed quantum classical methods can be obtained through
stationary phase approximations to the full quantum dynamics. A rigorous
description of the quantum corrections due to electronic nonadiabatic coupling
on the nuclear dynamics within the Ehrenfest framework is obtained. The fewest
switches surface hopping method is shown to be obtained as a quasiclassical
approximation to the dynamics and natural semiclassical extensions to include
classically forbidden nonadiabatic transitions are suggested.


title:
On the possibility of unifying the electromagnetic and the gravitational
  fields

abstract:
  This is the first paper by Gunnar Nordstr{\"o}m (1881--1923) on his five
dimensional theory. In his summary he states: ''It is shown, that a unifying
treatment of the electromagnetic and gravitational fields is possible, if one
considers the four dimensional spacetime world to be a surface in a five
dimensional world.'' This paper was followed by two other papers written by the
Gunnar Nordstr{\"o}m during the one year period 1914--1915, on the same
subject, which are also made available here.


title: On a theory of electricity and gravitation

abstract:
  This is the second paper by Nordstr{\"o}m on his five dimensional theory. It
aims at generalizing the relations $\mathbf{D} = \epsilon \mathbf{E}$,
$\mathbf{B} = \mu \mathbf{H}$ of electromagnetism to the five dimensional
gravito-electric theory and to show that this is consistent with the principle
of equivalence. Some steps are taken toward providing a foundation for a theory
of matter. Nordstr{\"o}m hopes, as stated in the conclusion, to show ''that the
five dimensional perspective, while still having only a formal content, may
however provide footholds for further developments of the theory of
gravitation, which otherwise would have been hard to find''.


title: On a possible foundation of a theory of matter

abstract:
  This is the third paper by Nordstr{\"o}m on his five dimensional theory. Here
Nordstr{\"o}m attempts to base a theory of matter on the energy conservation
generalized to the five dimensional case. This involves a new fundamental
constant related to the elementary electric charge.


title:
Modeling of Cables with High and Low Tension Zones using a Hybrid
  Rod-Catenary Formulation

abstract:
  Cables under very low tension may become highly contorted and form loops,
tangles, knots and kinks. These nonlinear deformations, which are dominated by
flexure and torsion, pose serious concerns for cable deployment. Simulation of
the three-dimensional nonlinear dynamics of loop and tangle formation requires
a 12th order rod model and the computational effort increases rapidly with
increasing cable length and integration time. However, marine cable
applications which result in local zones of low-tension very frequently involve
large zones of high-tension where the effects of flexure and torsion are
insignificant. Simulation of the three-dimensional dynamics of high-tension
cables requires only a 6th order catenary model which significantly reduces
computational effort relative to a rod model. We propose herein a hybrid
computational cable model that employs computationally efficient catenary
elements in high-tension zones and rod elements in localized low-tension zones
to capture flexure and torsion precisely where needed.


title: Waveplate retarders based on overhead transparencies

abstract:
  We describe procedures for constructing inexpensive waveplates of desired
retardation out of ordinary commercially available transparencies. Various
relevant properties of the transparencies are investigated: the dependence of
retardation on rotation of the film, tilt, wavelength, position, and
temperature. Constructing waveplates out of combinations of transparency sheets
is also explored.


title: Goos-Haenchen induced vector eigenmodes in a dome cavity

abstract:
  We demonstrate numerically calculated electromagnetic eigenmodes of a 3D dome
cavity resonator that owe their shape and character entirely to the
Goos-Haenchen effect. The V-shaped modes, which have purely TE or TM
polarization, are well described by a 2D billiard map with the Goos-Haenchen
shift included. A phase space plot of this augmented billiard map reveals a
saddle-node bifurcation; the stable periodic orbit that is created in the
bifurcation corresponds to the numerically calculated eigenmode, dictating the
angle of its "V". A transition from a fundamental Gaussian to a TM V mode has
been observed as the cavity is lengthened to become nearly hemispherical.


title:
Possible EIT-like effects in strong-field photodissociation of carbon
  disulphide

abstract:
  CS$_2$ molecules are spatially aligned upon irradiation by intense (1-100 TW
cm$^{-2}$), 35 ps pulses of 512 nm or 355 nm light. When both colours are
simultaneously present, spatial alignment disappears. We draw analogy with
weak-field illumination of an atom by two colours wherein EIT
(electromagnetically induced transparency) inhibits absorption by virtue of
dipoles not being induced in two-colour fields. In the strong field scenario,
molecular alignment is a consequence of a dipole being induced in the direction
of the applied electric field. It follows, therefore, that when dipoles are not
induced, no spatial alignment is to be expected.


title: Spherical Couette flow in a dipolar magnetic field

abstract:
  We consider numerically the flow of an electrically conducting fluid in a
differentially rotating spherical shell, in a dipolar magnetic field. For
infinitesimal differential rotation the flow consists of a super-rotating
region, concentrated on the particular field line C just touching the outer
sphere, in agreement with previous results. Finite differential rotation
suppresses this super-rotation, and pushes it inward, toward the equator of the
inner sphere. For sufficiently strong differential rotation the outer boundary
layer becomes unstable, yielding time-dependent solutions. Adding an overall
rotation suppresses these instabilities again. The results are in qualitative
agreement with the DTS liquid sodium experiment.


title: Acceleration of hydrodynamic vortices in open systems

abstract:
  A new class of exact solutions of hydrodynamic equations for an
incompressible fluid (gas) at the presence of a bulk sink and uprising vertical
flows of matter is considered. The acceleration of the rotation velocity of
classical non-stationary vortices is conditioned by the joint action of the
convective and Coriolis hydrodynamic forces (accelerations), which appear due
to the converging radial flows of the matter in the region of a bulk sink. It
is shown that there exist velocity profiles that nullify viscous terms in the
Navier-Stokes equations and represent a vortex structure with a "rigid-body"
rotation of its core and converging radial flows.
  The concept of non-stationary vortices in open systems is applied to
description of origination of power atmospheric vortices (whirlwinds, tornados,
and typhoons). In the classical hydrodynamics a favorable condition for the
origination and existence of such vortices is the exact nullification of the
terms, which describe kinematic viscosity of an incompressible fluid. Such
flows have the minimal rate of energy dissipation that corresponds to the
"minimum entropy production principle", and therefore may relatively easily
appear in favorable natural conditions.


title:
Band structure and Bloch states in birefringent 1D magnetophotonic
  crystals: An analytical approach

abstract:
  An analytical formulation for the band structure and Bloch modes in
elliptically birefringent magnetophotonic crystals is presented. The model
incorporates both the effects of gyrotropy and linear birefringence generally
present in magneto-optic thin film devices. Full analytical expressions are
obtained for the dispersion relation and Bloch modes in a layered stack
photonic crystal and their properties are analyzed. It is shown that other
models recently discussed in the literature are contained as special limiting
cases of the formulation presented herein.


title:
Actuation of Micro-Optomechanical Systems Via Cavity-Enhanced Optical
  Dipole Forces

abstract:
  We demonstrate a new type of optomechanical system employing a movable,
micron-scale waveguide evanescently-coupled to a high-Q optical microresonator.
Micron-scale displacements of the waveguide are observed for
milliwatt(mW)-level optical input powers. Measurement of the spatial variation
of the force on the waveguide indicates that it arises from a cavity-enhanced
optical dipole force due to the stored optical field of the resonator. This
force is used to realize an all-optical tunable filter operating with sub-mW
control power. A theoretical model of the system shows the maximum achievable
force to be independent of the intrinsic Q of the optical resonator and to
scale inversely with the cavity mode volume, suggesting that such forces may
become even more effective as devices approach the nanoscale.


title: Many-body Hamiltonian with screening parameter and ionization energy

abstract:
  We prove the existence of a new Hamiltonian that can be used to study
strongly correlated matter, which consists of the total energy at temperature
equals zero (E_0) and the ionization energy (\xi) as eigenvalues. We show that
the existence of this total energy eigenvalue, E_0 \pm \xi, does not violate
the Coulombian atomic system. Since there is no equivalent known Hamilton
operator that corresponds quantitatively to \xi, we employ the screened Coulomb
potential operator, which is a function of this ionization energy to
analytically calculate the screening parameter (\sigma) of a neutral Helium
atom in the ground state. In addition, we also show that the energy level
splitting due to spin-orbit coupling is inversely proportional to \xi
eigenvalue.


title: A Theory of Flavour and Set of the Interaction Structural Parts

abstract:
  At the availability of a sharp interconnection, the difference in sizes with
Dirac and Pauli form factors of a massive neutrino must constitute their
linearly ordered set. Such a class of currents can lead in the field of a
spinless nucleus to the constitution of a partially ordered set consisting of
cross sections of polarized and unpolarized neutrino scattering. We discuss a
theory, in which flavor conservation is predicted as a theorem about the
equality of cross sections of the interaction with a gauge boson of leptonic
current structural components. This theorem relates flavor and mirror
symmetries as a consequence of force unification forming the two left-(right-)
handed fermions in individual difermions. Thereby, it requires one to follow
the logic of a true nature of elementary particles from the point of view of a
flavor dynamics of all types of micro-world symmetry laws.


title: Reduction and approximation in gyrokinetics

abstract:
  The gyrokinetics formulation of plasmas in strong magnetic fields aims at the
elimination of the angle associated with the Larmor rotation of charged
particles around the magnetic field lines. In a perturbative treatment or as a
time-averaging procedure, gyrokinetics is in general an approximation to the
true dynamics. Here we discuss the conditions under which gyrokinetics is
either an approximation or an exact operation in the framework of reduction of
dynamical systems with symmetry


title:
Controlling the partial coalescence of a droplet on a vertically
  vibrated bath

abstract:
  A new method is proposed to stop the cascade of partial coalescences of a
droplet laid on a liquid bath. The strategy consists in vibrating the bath in
the vertical direction in order to keep small droplets bouncing. Since large
droplets are not able to bounce, they partially coalesce until they reach a
critical size. The system behaves as a low pass filter : droplets smaller than
the critical size are selected. This size has been investigated as a function
of the acceleration and the frequency of the bath vibration. Results suggest
that the limit size for bouncing is related to the first mode of the droplet
deformation.


title: Bleaching and diffusion dynamics in optofluidic dye lasers

abstract:
  We have investigated the bleaching dynamics that occur in optofluidic dye
lasers where the liquid laser dye in a microfluidic channel is locally bleached
due to optical pumping. We find that for microfluidic devices, the dye
bleaching may be compensated through diffusion of dye molecules alone. By
relying on diffusion rather than convection to generate the necessary dye
replenishment, our observation potentially allows for a significant
simplification of optofluidic dye laser device layouts, omitting the need for
cumbersome and costly external fluidic handling or on-chip microfluidic pumping
devices.


title:
First results of the two-phase argon avalanche detector performance with
  CsI photocathode

abstract:
  The performance of a two-phase Ar avalanche detector with CsI photocathode
was studied, with regard to potential application in coherent neutrino-nucleus
scattering and dark matter search experiments. The detector comprised a 1 cm
thick liquid Ar layer and a triple-GEM multiplier operated in the saturated
vapor above the liquid phase; the CsI photocathode was deposited on the first
GEM. Successful detection of both primary scintillation and ionization signals,
produced by beta-particles in liquid Ar, has for the first time been
demonstrated in the two-phase avalanche mode.


title:
Structure and static response of small silver clusters to an external
  electric field

abstract:
  The static response properties and the structural stability of silver
clusters in the size range $1\le n \le 23$ have been studied using a linear
combination of atomic Gaussian-type orbitals within the density functional
theory in the finite field approach. The Kohn-Sham equations have been solved
in conjuction with a generalized gradient approximation (GGA)
exchange-correlation functional. A proof that the finite basis set GGA
calculation holds the Hellmann-Feynman theorem is also included in the
Appendix. The calculated polarizabilities of silver clusters are compared with
the experimental measurements and the jellium model in the spillout
approximation. Despite the fact that the calculated polarizabilities are in
good agreement with both of them, we have found that the polarizability appears
to be strongly correlated to the cluster shape and the highest occupied-lowest
unoccupied molecular-orbital gap.


title: How to create a universe

abstract:
  The purpose of this paper is (i) to expound the specification of a universe,
according to those parts of mathematical physics which have been experimentally
and observationally verified in our own universe; and (ii) to expound the
possible means of creating a universe in the laboratory.


title: Bayesian estimation of GARCH model by hybrid Monte Carlo

abstract:
  The hybrid Monte Carlo (HMC) algorithm is used for Bayesian analysis of the
generalized autoregressive conditional heteroscedasticity (GARCH) model. The
HMC algorithm is one of Markov chain Monte Carlo (MCMC) algorithms and it
updates all parameters at once. We demonstrate that how the HMC reproduces the
GARCH parameters correctly. The algorithm is rather general and it can be
applied to other models like stochastic volatility models.


title:
Imaging cardiac dynamics using low-cost ultra-high-power light emitting
  diodes and voltage-sensitive dyes

abstract:
  We describe the characteristics of low-cost ultra-high-power light emitting
diodes (LEDs) for use in optical imaging experiments. We use the LEDs in
experiments with bullfrog cardiac tissue and find that the signal-to-noise
ratio is comparable to other commonly used illumination sources.


title: Muon Telescope at BEO - Moussala

abstract:
  A muon telescope based on 8 water cherenkov detectors was mounted at Basic
Environmental Observatory - Moussala - Institute for Nuclear Research and
Nuclear Energy - Bulgarian Academy of Science. The telescope will be used for
continuous measuring the intensity of the muon component of cosmic rays,
exploring its variations and possible correlations with environment parameters.
A detailed description of the device is presented in this paper.


title:
Interferometry of a Single Nanoparticle Using the Gouy Phase of a
  Focused Laser Beam

abstract:
  We provide a quantitative explanation of the mechanism of the far-field
intensity modulation induced by a nanoparticle in a focused Gaussian laser
beam, as was demonstrated in several recent direct detection studies. Most
approaches take advantage of interference between the incident light and the
scattered light from a nanoparticle to facilitate a linear dependence of the
signal on the nanoparticle volume. The phase relation between the incoming
field and the scattered field by the nanoparticle is elucidated by the concept
of Gouy phase. This phase relation is used to analyze the far-field
signal-to-noise ratio as a function of exact nanoparticle position with respect
to the beam focus. The calculation suggests that a purely dispersive
nanoparticle should be displaced from the Gaussian beam focus to generate a
far-field intensity change.


title: Einstein, Levi-Civita, and Bianchi relations

abstract:
  About an essential suggestion to Einstein by Levi-Civita in 1915. Unicuique
suum.


title: Effective optical constants in stratified metal-dielectric metameterial

abstract:
  We present effective optical constants of stratified metal-dielectric
metameterial. The effective constants are determined by two complex
reflectivity method (TCRM). TCRM reveals full components of effective
permittivity and permeability tensors and indicates the remarkable anisotropy
of metallic and dielectric components below effective plasma frequency. On the
other hand, above the plasma frequency, one of the effective refractive indexes
takes a positive value less than unity and is associated with small loss. The
photonic states are confirmed by the distribution of electromagnetic fields.


title: A Pair Polarimeter for Linearly Polarized High Energy Photons

abstract:
  A high quality beam of linearly polarized photons of several GeV will become
available with the coherent bremsstrahlung technique at JLab. We have developed
a polarimeter which requires about two meters of the beam line, has an
analyzing power of 20% and an efficiency of 0.02%. The layout and first results
of a polarimeter test on the laser back-scattering photon beam at SPring-8/LEPS
are presented.


title:
The Development of an Inquiry-based Curriculum Specifically for the
  Introductory Algebra-based Physics Course

abstract:
  We discuss an inquiry-based curriculum that has been developed specifically
for the introductory algebra-based physics course, taking into account the
needs, backgrounds, learning styles and career goals of the students in that
class. The course is designed to be taught in a laboratory-based environment,
however parts of the materials can be used in other settings. As instructors we
found ourselves drawing on materials developed for the calculus-based course
and for other populations (materials developed for pre-service teachers, for
example), parts of which were appropriate, but not a complete curriculum as we
would like to teach it, developed specifically for students in the introductory
algebra-based physics course. So we have modified and adapted parts of existing
materials and integrated them with our own new units and our own format,
creating a course aimed specifically at these students.


title:
The uniqueness of company size distribution function from tent-shaped
  growth rate distribution

abstract:
  We report the proof that the extension of Gibrat's law in the middle scale
region is unique and the probability distribution function (pdf) is also
uniquely derived from the extended Gibrat's law and the law of detailed
balance. In the proof, two approximations are employed. The pdf of growth rate
is described as tent-shaped exponential functions and the value of the origin
of the growth rate distribution is constant. These approximations are confirmed
in profits data of Japanese companies 2003 and 2004. The resultant profits pdf
fits with the empirical data with high accuracy. This guarantees the validity
of the approximations.


title:
Sub-lambda gratings, surface plasmons, hotter electrons and brighter
  x-ray sources- enhanced absorption of intense, ultrashort laser light by tiny
  surface modulations

abstract:
  We observe near 100 % absorption of light in intense ultrashort laser plasma
interaction in a metal coated (Au on glass) sub-lambda grating structure under
suitable conditions and the subsequent 'hot' electron generation from the
grating plasma. In the low intensity regime we determine the conditions in
which a monochromatic infrared light (lambda = 800nm corresponding to the
central wavelength of the ultrashort laser that we used in subsequent
experiments) efficiently excites surface plasmon in the grating. Then we study
how the surface plasmon resonance condition changes when we excite them using
low intensity ultrashort pulses. We look at the reflectivity of light varying
the incident light intensity over a wide range (2x10e12Wcm-2-2x10e15Wcm-2). The
reflectivity of grating with the resonance condition satisfied is the lowest
over the whole range of intensity. We compare the data with those obtained from
highly polished (lambda/10) Au mirror target under identical conditions. At
high intensities we look at the hard x-ray emission from both the targets with
and without the resonance condition. The hard X-ray spectrum shows a
bimaxwellian i.e two temperature hot electron distribution with a hotter
component present under the resonance condition while in all other cases it
shows the presence of only one low temperature component.


title: Quantum-like Probabilistic Models outside Physics

abstract:
  We present a quantum-like (QL) model in that contexts (complexes of e.g.
mental, social, biological, economic or even political conditions) are
represented by complex probability amplitudes. This approach gives the
possibility to apply the mathematical quantum formalism to probabilities
induced in any domain of science. In our model quantum randomness appears not
as irreducible randomness (as it is commonly accepted in conventional quantum
mechanics, e.g., by von Neumann and Dirac), but as a consequence of obtaining
incomplete information about a system. We pay main attention to the QL
description of processing of incomplete information. Our QL model can be useful
in cognitive, social and political sciences as well as economics and artificial
intelligence. In this paper we consider in a more detail one special
application -- QL modeling of brain's functioning. The brain is modeled as a
QL-computer.


title:
Properties of a thin metal layer as a tool in focusing (projecting)
  procedure

abstract:
  The field of an evanescent wave in a space with a thin metal layer is
explored. The wave number of the evanescent wave exceeds many times the wave
number of a uniform plane wave in adjoining gaps. In agreement with the results
of the Pendry's paper of the 2000 year the field behind the metal layer occurs
to be amplified as compared to the field in absence of the metal layer. Pendry
has demonstrated the effect for the metal of the dielectric constant of -1. In
this paper it is shown that the effect exists for the dielectric constant of
-15 and for an arbitrary thickness of the adjoining gaps. This widens the
number of possible applications. The metal losses do not destoy the effect
appreciably.


title:
Radiation pressure driven vibrational modes in ultra-high-Q silica
  microspheres

abstract:
  Quantitative measurements of the vibrational eigenmodes in ultra-high-Q
silica microspheres are reported. The modes are efficiently excited via
radiation-pressure induced dynamical back-action of light confined in the
optical whispering-gallery modes of the microspheres (i.e. via the parametric
oscillation instability). Two families of modes are studied and their frequency
dependence on sphere size investigated. The measured frequencies are in good
agreement both with Lamb's theory and numerical finite element simulation and
are found to be proportional to the sphere's inverse diameter.


title:
The geometrical nature and some properties of the capacitance
  coefficients based on Laplace's Equation

abstract:
  The fact that the capacitance coefficients for a set of conductors are
geometrical factors is derived in most electricity and magnetism textbooks. We
present an alternative derivation based on Laplace's equation that is
accessible for an intermediate course on electricity and magnetism. The
properties of Laplace's equation permits to prove many properties of the
capacitance matrix. Some examples are given to illustrate the usefulness of
such properties.


title: Physics behind the Debye temperature

abstract:
  Textbooks introduce the Debye temperature to simplify the integration of the
heat capacity. This approach gives the impression that the Debye temperature is
a parameter which makes the integration more convenient. The Debye frequency
cut occurs when the wavelength of the phonon frequency reaches the size of the
smallest unit of the lattice which is the length of the unit cell. At
frequencies higher than the cut off frequency the 'lattice' unable to 'see' the
vibration because the wavelength of the vibration is smaller than the basic
unit of the atomic arrangement; therefore, the vibration becomes independent
from the lattice. The Debye cut off frequency or temperature separates the
collective thermal lattice vibration from the independent thermal lattice
vibration. The experimental data of highest packing monoatomic arrangements is
used to calculate the wavelength of the Debye cut off frequency. The calculated
values agree well with the unit cell parameters.


title: Special Relativity properties from Minkowski diagrams

abstract:
  This paper has pedagogical motivation. It is not uncommon that students have
great difficulty in accepting the new concepts of standard special relativity,
since these seem contrary to common sense. Experience shows that geometrical or
graphically exposition of the basic ideas of relativity theory improves student
understanding of the algebraic expressions of the theory. What we suggest here
may complement standard textbook approaches.


title: Meta-materials with negative refractive index at Optical Frequencies

abstract:
  We demonstrate that arrays of split ring resonators (SRR) can have negative
refractive index at optical frequencies (~1.4 eV). Our calculations reveal that
the electric fields of radiation interact strongly with even symmetric SRR at
optical frequencies as the size of the SRR becomes of the order of the
wavelength (~lambda /3) for practicably realizable structures. We also
demonstrate by calculations the focussing of a line source by a flat slab of a
(2D) SRR medium. The negative refractive index here is related to the plasmonic
excitations of the SRR and cannot be directly explained by the usual paradigm
of negative dielectric permittivity and negative magnetic permeability in these
limits when homogenization breaks down.


title: Computation of Electrostatic and Gravitational Sag in MultiWire Chambers

abstract:
  A numerical method of determining the wire sag in a multiwire proportional
chamber used in RICH (ALICE) by solving the second order differential equation
which governs the wire stability has been presented. The three point Finite
Difference Method (FDM) has generated a tridiagonal matrix equation relating
the deflection of wire segments to the force acting on it. The precise
estimates of electrostatic force has been obtained from accurate field
computation using a nearly exact Boundary Element Method (neBEM) solver.


title:
A Note On Steady Flow of Incompressible Fluid Between Two Co-rotating
  Disks

abstract:
  The article provides an analytical solution of the Navier-Stokes equations
for the case of the steady flow of an incompressible fluid between two
uniformly co-rotating disks. The solution is derived from the asymptotical
evolution of unknown components of velocity and pressure in a radial
direction--in contrast to the Briter-Pohlhausen analytical solution, which is
supported by simplified Navier-Stokes equations. The obtained infinite system
of ordinary differential equations forms recurrent relations from which unknown
functions can be calculated successively. The first and second approximations
of solution are solved analytically and the third and fourth approximations of
solutions are solved numerically. The numerical example demonstrates agreements
with results obtained by other authors using different methods.


title: Simulation of Pickup Signal in a Resistive Plate Chamber

abstract:
  The signal induced by an electron on a pickup strip has been calculated in a
RPC used in INO calorimeter following Ramo's theorem. An accurate estimation of
weighting field has been obtained using a nearly exact Boundary Element Method
(neBEM) solver while the electron velocity from the real field values. The
calculation has shown a growth and subsequent fall of pickup signal with
duration about 90ps.


title:
Ab initio phenomenological simulation of the growth of large tumor cell
  populations

abstract:
  In a previous paper we have introduced a phenomenological model of cell
metabolism and of the cell cycle to simulate the behavior of large tumor cell
populations (Chignola R and Milotti E, Phys. Biol. 2 (2005) 8-22). Here we
describe a refined and extended version of the model that includes some of the
complex interactions between cells and their surrounding environment. The
present version takes into consideration several additional energy-consuming
biochemical pathways such as protein and DNA synthesis, the tuning of
extracellular pH and of the cell membrane potential. The control of the cell
cycle - that was previously modeled by means of ad hoc thresholds - has been
directly addressed here by considering checkpoints from proteins that act as
targets for phosphorylation on multiple sites. As simulated cells grow, they
can now modify the chemical composition of the surrounding environment which in
turn acts as a feedback mechanism to tune cell metabolism and hence cell
proliferation: in this way we obtain growth curves that match quite well those
observed in vitro with human leukemia cell lines. The model is strongly
constrained and returns results that can be directly compared with actual
experiments, because it uses parameter values in narrow ranges estimated from
experimental data, and in perspective we hope to utilize it to develop in
silico studies of the growth of very large tumor cell populations (10^6 cells
or more) and to support experimental research. In particular, the program is
used here to make predictions on the behaviour of cells grown in a glucose-poor
medium: these predictions are confirmed by experimental observation.


title: Estimation of Weighting Potential for a TPC

abstract:
  In this work, we have computed the three dimensional weighting potential,
field and pad response function (PRF) of typical time projection chambers (TPC)
using a recently formulated and developed boundary element method solver,
namely, the nearly exact BEM solver. A realistic geometry of the device is
found to have significant influence on the estimation of signal generation.


title: 3D Simulation of New Generation Gas Detectors

abstract:
  Simulation of new generation gas detectors is rendered complicated due to the
non-trivial nature of the electric field and simultaneous presence of several
length-scales. Computation of the electrostatic field, however, is extremely
important since streamers in gas volume and streamers across the dielectric
surfaces are known to cause serious damage to Micro Pattern Gas Detectors
(MPGD)and are the main factors in limiting their gain. In this paper, we
present the use of a nearly exact Boundary Element Method (neBEM) solver that
overcomes most of the limitations of FEM packages and is capable of producing
accurate results.


title:
New Approach to the Characterization of Mmax and of the Tail of the
  Distribution of Earthquake Magnitudes

abstract:
  We develop a new method for the statistical esitmation of the tail of the
distribution of earthquake sizes recorded in the Worldwide Harvard catalog of
seismic moments converted to mW-magnitudes (1977-2004 and 1977-2006). We show
that using the set of maximum magnitudes (the set of T-maxima) in windows of
duration T days provides a significant improvement over existing methods, in
particular (i) by minimizing the negative impact of time-clustering of
foreshock / main shock /aftershock sequences in the estimation of the tail of
the magnitude distribution, and (ii) by providing via a simulation method
reliable estimates of the biases in the Moment estimation procedure (which
turns out to be more efficient than the Maximum Likelihood estimation). Using a
simulation method, we have determined the optimal window size of the T-maxima
to be T=500 days. We have estimated the following quantiles of the distribution
of T-maxima of earthquake magnitudes for the whole period 1977-2006:
Q_{0.16}(Mmax)=9.3, Q_{0.5}(Mmax)=9.7 and Q_{0.84}(Mmax)=10.3. Finally, we
suggest two more stable statistical characterristics of the tail of the
distribution of earthquake magnitudes: the quantile QT(q) of a high probability
level q for the T-maxima, and the probability of exceedence for a high
threshold magnitude. We obtained the following sample estimates for the global
Harvard catalog: QT(q=0.98)=8.6 +- 0.2 and a probability for the T-maxima to
exceed magnitude 8 equal to 0.13-0.20. The comparison between our estimates for
the two periods 1977-2004 and 1977-2006, where the later period includes the
great Sumatra earthquake, 24.12.2004, mW=9.0, confirms the instability of the
estimation of the parameter Mmax and the stability of the two other estimates.


title:
Accuracy of one-dimensional collision integral in the rigid spheres
  approximation

abstract:
  The accuracy of calculation of spectral line shapes in one-dimensional
approximation is studied analytically in several limiting cases for arbitrary
collision kernel and numerically in the rigid spheres model. It is shown that
the deviation of the line profile is maximal in the center of the line in case
of large perturber mass and intermediate values of collision frequency. For
moderate masses of buffer molecules the error of one-dimensional approximation
is found not to exceed 5%.


title:
Observation of Enhanced Transformer Ratio in Collinear Wakefield
  Acceleration

abstract:
  One approach to future high energy particle accelerators is based on the
wakefield principle: a leading high-charge drive bunch is used to excite fields
in an accelerating structure or plasma that in turn accelerates a trailing
low-charge witness bunch. The transformer ratio R is defined as the ratio of
the maximum energy gain of the witness bunch to the maximum energy loss of the
drive bunch. In general, for configurations in which the two beams traverse the
accelerator along the same trajectory (collinear wakefield acceleration). A
number of techniques have been proposed to overcome the transformer ratio
limitation. We report here the first experimental study of the ramped bunch
train (RBT) technique in which a dielectric loaded waveguide was used as the
accelerating structure. A single drive bunch was replaced by two bunches with
charge ratio of 1:2.5 and a separation of 10.5 wavelengths of the fundamental
mode. An average measured transformer ratio enhancement by a factor of 1.31
over the single drive bunch case was obtained in this experiment.


title: AB Levitator and Electricity Storage

abstract:
  The author researched this new idea - support of flight by any aerial
vehicles at significant altitude solely by the magnetic field of the planet. It
is shown that current technology allows humans to create a light propulsion (AB
engine) which does not depend on air, water or ground terrain. Simultaniosly,
this revolutionary thruster is a device for the storage of electricity which is
extracted and is replenished (during braking) from/into the storage with 100
percent efficiency. The relative weight ratio of this engine is 0.01 - 0.1
(from thrust). For some types of AB engine (toroidal form) the thrust easily
may be changed in any direction without turning of engine.
  The author computed many projects using different versions of offered AB
engine: small device for levitation-flight of a human (including flight from
Earth to Outer Space), fly VTOL car (track), big VTOL aircrat, suspended low
altitude stationary satellite, powerful Space Shuttle-like booster for travel
to the Moon and Mars without spending energy (spended energy is replenished in
braking when ship returns from other planet to its point of origin), using
AB-devices in military, in sea-going ships (submarimes), in energy industry
(for example. as small storage of electric energy) and so on. The vehicles
equipped with AB propulsion can take flight for days and cover distances of
tens thousands of kilometers at hypersonic or extra-atmosphere space speeds.
  The work contains tens of inventions and innovations which solves problems
and breaks limitations which appear in solution of these very complex
revolutionary ideas.
  Key word: AB levitator, levitation, non-rocket outer space flight, electric
energy storage, AB propulsion, AB engine, Bolonkin.


title:
Plasma metric singularities in helical devices and tearing instabilities
  in tokamaks

abstract:
  Plasma toroidal metric singularities in helical devices and tokamaks, giving
rise to magnetic surfaces inside the plasma devices are investigated in two
cases. In the first we consider the case of a rotational plasma on an helical
device with circular cross-section and dissipation. In this case singularities
are shown to place a Ricci scalar curvature bound on the radius of the surface
where the Ricci scalar is the contraction of the constant Riemannian curvature
tensor of magnetic surfaces. An upper bound on the initial magnetic field in
terms of the Ricci scalar is obtained. This last bound may be useful in the
engineering construction of plasma devices in laboratories. The normal poloidal
drift velocity is also computed. In the second case a toroidal metric is used
to show that there is a relation between singularities and the type of tearing
instabilities considered in the tokamak. Besides, in this case Ricci
collineations and Killing symmetries are computed.The pressure is computed by
applying these constraints to the pressure equations in tokamaks.


title:
Comment on "The effect of variable viscosity on mixed convection heat
  transfer along a vertical moving surface" by M. Ali

abstract:
  The problem of forced convection along an isothermal moving plate is a
classical problem of fluid mechanics that has been solved for the first time in
1961 by Sakiadis (1961). It appears that the first work concerning mixed
convection along a moving plate is that of Moutsoglou and Chen (1980).
Thereafter, many solutions have been obtained for different aspects of this
class of boundary layer problems. In the previous works the fluid properties
have been assumed constant. Ali (2006) in a recent paper treated, for the first
time, the mixed convection problem with variable viscosity. He used the local
similarity method to solve this problem but there are doubts about the validity
of his results. For that reason we resolved the above problem with the direct
numerical solution of the boundary layer equations without any transformation.


title:
Comment on "The effect of variable viscosity on the flow and heat
  transfer on a continuous stretching surface"

abstract:
  The problem of forced convection along an isothermal, constantly moving plate
is a classical problem of fluid mechanics that has been solved for the first
time in 1961 by Sakiadis (1961). Thereafter, many solutions have been obtained
for different aspects of this class of boundary layer problems. Solutions have
been appeared including mass transfer, varying plate velocity, varying plate
temperature, fluid injection and fluid suction at the plate. The work by
Hassanien (1997) belongs to the above class of problems, including a linearly
varying velocity and the variation of fluid viscosity with temperature. The
author obtained similarity solutions considering that viscosity varies as an
inverse function of temperature. However, the Prandtl number, which is a
function of viscosity, has been considered constant across the boundary layer.
It has been already confirmed in the literature that the assumption of constant
Prandtl number leads to unrealistic results (Pantokratoras, 2004, 2005). The
objective of the present paper is to obtain results considering both viscosity
and Prandtl number variable across the boundary layer. The differences of the
two methods are very large in some cases.


title:
Comment on "Investigation of simplified thermal expansion models for
  compressible Newtonian fluids applied to nonisothernal plane Couette and
  Poiseuille flows" by S. Bechtel et al

abstract:
  In the above paper by Bechtel, Cai, Rooney and Wang, Physics of Fluids, 2004,
16, 3955-3974 six different theories of a Newtonian viscous fluid are
investigated and compared, namely, the theory of a compressible Newtonian
fluid, and five constitutive limits of this theory: the incompressible theory,
the limit where density changes only due to changes in temperature, the limit
where density changes only with changes in entropy, the limit where pressure is
a function only of temperature, and the limit of pressure a function only of
entropy. The six theories are compared through their ability to model two test
problems: (i) steady flow between moving parallel isothermal planes separated
by a fixed distance with no pressure gradient in the flow direction (Couette
flow), and (ii) steady flow between stationary isothermal parallel planes with
a pressure gradient (Poiseuille flow). The authors found, among other, that the
incompressible theory admits solutions to these problems of the plane
Couette/Poiseuille flow form: a single nonzero velocity component in a
direction parallel to the bounding planes, and velocity and temperature varying
only in the direction perpendicular to the planes.


title: A discontinuity of the background explains the Pioneer anomaly

abstract:
  The Pioneer anomaly is explained very simply if we assume that somewhere
between us and the aircraft, the scale factor has undergone a discrete jump
from an expansion a(t) regime to a contraction 1/a(t) regime


title: Quantum Foundations : Is Probability Ontological ?

abstract:
  It is argued that the Copenhagen Interpretation of Quantum Mechanics, founded
ontologically on the concept of probability, may be questionable in view of the
fact that within Probability Theory itself the ontological status of the
concept of probability has always been, and is still under discussion.


title: Electron acceleration by colliding laser beams in plasmas

abstract:
  All-optical controlled injection and acceleration of electrons in a laser
wakefield has recently been achieved (Faure et al, Nature v. 444 p. 737, 2006).
Injection was made using a second counterpropagating laser pulse with the same
polarization as the main pulse . In this scheme, the interference pattern
formed during the collision between the pulses pre-accelerates electrons that
are then trapped in the wakefield. Numerical simulations of this process
performed with a new Particle-in-Cell code are presented here. The results show
the nature of the injection mechanism and explain some striking features found
experimentally, such as the dependence of beam energy with the collision
position and the reduction of the charge at high energies. Simulations
reproduce well the main features of the experimental observations.


title:
The role of inflexible minorities in the breaking of democratic opinion
  dynamics

abstract:
  We study the effect of inflexible agents on two state opinion dynamics. The
model operates via repeated local updates of random grouping of agents. While
floater agents do eventually flip their opinion to follow the local majority,
inflexible agents keep their opinion always unchanged. It is a quenched
individual opinion. In the bare model (no inflexibles), a separator at 50%
drives the dynamics towards either one of two pure attractors, each associated
with a full polarization along one of the opinions. The initial majority wins.
The existence of inflexibles for only one of the two opinions is found to shift
the separator at a lower value than 50% in favor of that side. Moreover it
creates an incompressible minority around the inflexibles, one of the pure
attractors becoming a mixed phase attractor. In addition above a threshold of
17% inflexibles make their side sure of winning whatever the initial conditions
are. The inflexible minority wins. An equal presence of inflexibles on both
sides restores the balanced dynamics with again a separator at 50% and now two
mixed phase attractors on each side. Nevertheless, beyond 25% the dynamics is
reversed with a unique attractor at a fifty-fifty stable equilibrium. But a
very small advantage in inflexibles results in a decisive lowering of the
separator at the advantage of the corresponding opinion. A few percent
advantage does guarantee to become majority with one single attractor. The
model is solved exhaustedly for groups of size 3.