title: Maximum-likelihood estimation prevents unphysical Mueller matrices

abstract:
  We show that the method of maximum-likelihood estimation, recently introduced
in the context of quantum process tomography, can be applied to the
determination of Mueller matrices characterizing the polarization properties of
classical optical systems. Contrary to linear reconstruction algorithms, the
proposed method yields physically acceptable Mueller matrices even in presence
of uncontrolled experimental errors. We illustrate the method on the case of an
unphysical measured Mueller matrix taken from the literature.


title: Condition of Multibubble Sonofusion and Proposal of Experimental Setup

abstract:
  We consider that multibubble sonoluminescence (MBSL) sonofusion is necessary
for the industrial use of sonofusion. In 2002, Taleyarkhan et al. [Science,
295, 1868, (2002)] reported neutron radiation from single-bubble
sonoluminescence (SBSL), thereafter sonofusion has been discussed. However,
SBSL, as described in the literature, is only one bubble, then the energy of
sonofusion has a strict limitation for industrial use, that is, very little
production of energy. MBSL is a cluster of bubbles; therefore, if sonofusion
occurs in MBSL, a large amount of energy can be obtained. We assume the
difference between SBSL and MBSL is temperature, thus we propose experimental
setup of sonofusion, in which sonoplasma raises the temperature of MBSL.


title: Node Exchange Network and its Statistical Analysis

abstract:
  In considering a social network, there are cases where people is transferred
to another place. Then the physical (direct) relations among nodes are lost by
the movement. In terms of a network theory, some nodes break the present
connections with neighboring nodes, move and there build new connections of
nodes. For simplicity we here consider only that two nodes exchange the place
each other on a network. Such exchange is assumed to be constantly carried out.
We study this dynamic network (node exchange network NEN) and uncover some new
features which usual networks do not contain. We mainly consider average path
length and the diameter. Lastly we consider a propagation of one virus on the
network by a computer simulation. They are compared to other networks
investigated hitherto. The relation to a scale free network is also discussed.


title: Does the subtropical jet catalyze the mid-latitude atmospheric regimes?

abstract:
  Understanding the atmospheric low-frequency variability is of crucial
importance in fields such as climate studies, climate change detection, and
extended-range weather forecast. The Northern Hemisphere climate features the
planetary waves as a relevant ingredient of the atmospheric variability.
Several observations and theoretical arguments seem to support the idea that
winter planetary waves indicator obey a non-Gaussian statistics and may present
a multimodal probability density function, thus characterizing the
low-frequency portion of the climate system. We show that the upper
tropospheric jet strength is a critical parameter in determining whether the
planetary waves indicator exhibits a uni- or bimodal behavior, and we determine
the relevant threshold value of the jet. These results are obtained by
considering the data of the NCEP-NCAR and ECMWF reanalyses for the overlapping
period. Our results agree with the non-linear orographic theory, which explains
the statistical non-normality of the low-frequency variability of the
atmosphere and its possible bimodality.


title: Self-organizing social hierarchies in a timid society

abstract:
  Emergence of hierarchies is investigated by Monte Carlo simulation in a timid
society where all individuals are pacifist. The self-organiztion of hierarchies
is shown to occur in two steps as the population is increased, i.e. there are
three states, one egalitarian and two hierarchical states;the transition from
the egalitarian to the first hierarchical state is continuous and the
transition from the first hierachical state to the second one is discontinuous.
In the first hierarchical society, all individuals belong to either middle
class or losers and no winners appear. In the second hierarchical society, many
winners emerge and the population of the middle class is reduced. The hierarchy
in the second hierarchical society is stronger than the hierachy in a
no-preference society studied by Bonabeau et al [ Physica A{\bf 217}, 373
(1995)]


title: Alexandru Proca (1897--1955) the Great Physicist

abstract:
  We commemorate 50 years from A. Proca's death. Proca equation is a
relativistic wave equation for a massive spin-1 particle. The weak interaction
is transmitted by such kind of vector bosons. Also vector fields are used to
describe spin-1 mesons (e.g. $\rho$ and $\omega$ mesons). After a brief
biography, the paper presents an introduction into relativistic field theory,
including Klein-Gordon, Dirac, and Maxwell fields, allowing to understand this
scientific achievement and some consequences for the theory of strong
interactions as well as for Maxwell-Proca and Einstein-Proca theories. The
modern approach of the nonzero photon mass and the superluminal radiation field
are also mentioned.


title: Measurement of atomic diffraction phases induced by material gratings

abstract:
  Atom-surface interactions can significantly modify the intensity and phase of
atom de Broglie waves diffracted by a silicon nitride grating. This affects the
operation of a material grating as a coherent beam splitter. The phase shift
induced by diffraction is measured by comparing the relative phases of serveral
interfering paths in a Mach-Zehnder Na atom interferometer formed by three
material gratings. The values of the diffraction phases are consistent with a
simple model which includes a van der Waals atom-surface interaction between
the Na atoms and the silicon nitride grating bars.


title:
Matter-Wave Decoherence due to a Gas Environment in an Atom
  Interferometer

abstract:
  Decoherence due to scattering from background gas particles is observed for
the first time in a Mach-Zehnder atom interferometer, and compared with
decoherence due to scattering photons. A single theory is shown to describe
decoherence due to scattering either atoms or photons. Predictions from this
theory are tested by experiments with different species of background gas, and
also by experiments with different collimation restrictions on an atom beam
interferometer.


title:
Calibration of CMS calorimeters with LHC proton beam deflected by
  crystal

abstract:
  Calibration of the forward CMS hadron calorimeters in situ by the LHC beam is
proposed. Simulations show that bent crystal channeling technique is feasible
at the LHC, and report the experience of IHEP Protvino in bending 70 GeV
protons by 9 degrees (150 mrad) during 10 years in 1994-2004 experiments.
Practical realization of calibration scheme based on simulations and previous
experience is proposed.


title: A selected history of expectation bias in physics

abstract:
  The beliefs of physicists can bias their results towards their expectations
in a number of ways. We survey a variety of historical cases of expectation
bias in observations, experiments, and calculations.


title: The Hydraulic Jump in Liquid Helium

abstract:
  We present the results of some experiments on the circular hydraulic jump in
normal and superfluid liquid helium. The radius of the jump and the depth of
the liquid outside the jump are measured through optical means. Although the
scale of the apparatus is rather small, the location of the jump is found to be
consistent with the assumption that the jump can be treated as a shock, if the
surface tension is taken into account. The radius of the jump does not change
when going down in temperature through the lambda point; we think that the flow
is supercritical. A remarkable feature of the experiment is the observation of
stationary ripples within the jump when the liquid is superfluid.


title: The Zeta Function Method and the Harmonic Oscillator Propagator

abstract:
  We show how the pre-exponential factor of the Feynman propagator for the
harmonic oscillator can be computed by the generalized $\zeta$-function method.
Besides, we establish a direct equivalence between this method and Schwinger's
propertime method.


title: Path Integral and the Induction Law

abstract:
  We show how the induction law is correctly used in the path integral
computation of the free particle propagator. The way this primary path integral
example is treated in most textbooks is a little bit missleading.


title: Impact of Stock Market Structure on Intertrade Time and Price Dynamics

abstract:
  The NYSE and NASDAQ stock markets have very different structures and there is
continuing controversy over whether differences in stock price behaviour are
due to market structure or company characteristics. As the influence of market
structure on stock prices may be obscured by exogenous factors such as demand
and supply, we hypothesize that modulation of the flow of transactions due to
market operations may carry a stronger imprint of the internal market
mechanism. We analyse times between consecutive transactions (ITT) for NYSE and
NASDAQ stocks, and we relate the dynamical properties of the ITT with those of
the corresponding price fluctuations. We find a robust scale-invariant temporal
organisation in the ITT of stocks which is independent of individual company
characteristics and industry sector, but which depends on market structure. We
find that stocks registered on the NASDAQ exhibit stronger correlations in
their transaction timing within a trading day, compared with NYSE stocks.
Further, we find that companies that transfer from the NASDAQ to the NYSE show
a reduction in the correlation strength of transaction timing within a trading
day, after the move, suggesting influences of market structure. Surprisingly,
we also observe that stronger power-law correlations in the ITT are coupled
with stronger power-law correlations in absolute price returns and higher price
volatility, suggesting a strong link between the dynamical properties of ITT
and the corresponding price fluctuations over a broad range of time scales.
Comparing the NYSE and NASDAQ, we demonstrate that the higher correlations we
find in ITT for NASDAQ stocks are matched by higher correlations in absolute
price returns and by higher volatility, suggesting that market structure may
affect price behaviour through information contained in transaction timing.


title: Compact Quasi-Chaotic Optical Cavity

abstract:
  A novel, 3-dimensional, convex, multi-pass optical cavity with
partially-chaotic ray dynamics is presented. The light is localized near
stable, long-path length trajectories supported by the cavity, and beam
diffraction is suppressed by the phase space barriers between the regions of
regular and chaotic ray dynamics that are generally present in
partially-chaotic systems. For a centimeter-size cavity, the design supports
meter-scale optical path lengths, suggesting future applications in trace gas
detection. An exemplary cavity has been fabricated from a hollow, gold-coated,
acrylic shell. Our measurements using a HeNe laser and a pulsed red diode laser
for characterization of the cavity beam pattern and optical path length,
respectively, confirm the theoretically predicted optical dynamics and the
ability of the cavity to support meter-scale path lengths.


title: Mutual Support in Agent Networks

abstract:
  We construct a model of social behaviour through the dynamics of interacting
agents. The agents undergo game-theoretic interactions where each agent can
decide to lend support to particular other agents or otherwise, and agents are
rewarded according to total support received. We analyse and carry out Monte
Carlo simulations of such systems to uncover their evolutionary dynamics, and
to explore their phase structure.


title: The Network of Inter-Regional Direct Investment Stocks across Europe

abstract:
  We propose a methodological framework to study the dynamics of inter-regional
investment flow in Europe from a Complex Networks perspective, an approach with
recent proven success in many fields including economics. In this work we study
the network of investment stocks in Europe at two different levels: first, we
compute the inward-outward investment stocks at the level of firms, based on
ownership shares and number of employees; then we estimate the inward-outward
investment stock at the level of regions in Europe, by aggregating the
ownership network of firms, based on their headquarter location. Despite the
intuitive value of this approach for EU policy making in economic development,
to our knowledge there are no similar works in the literature yet. In this
paper we focus on statistical distributions and scaling laws of activity,
investment stock and connectivity degree both at the level of firms and at the
level of regions. In particular we find that investment stock of firms is power
law distributed with an exponent very close to the one found for firm activity.
On the other hand investment stock and activity of regions turn out to be
log-normal distributed. At both levels we find scaling laws relating investment
to activity and connectivity. In particular, we find that investment stock
scales with connectivity in a similar way as has been previously found for
stock market data, calling for further investigations on a possible general
scaling law holding true in economical networks.


title: Physics and metaphysics looks at computation

abstract:
  As far as algorithmic thinking is bound by symbolic paper-and-pencil
operations, the Church-Turing thesis appears to hold. But is physics, and even
more so, is the human mind, bound by symbolic paper-and-pencil operations? What
about the powers of the continuum, the quantum, and what about human intuition,
human thought? These questions still remain unanswered. With the strong
Artificial Intelligence assumption, human consciousness is just a function of
the organs (maybe in a very wide sense and not only restricted to neuronal
brain activity), and thus the question is relegated to physics. In dualistic
models of the mind, human thought transcends symbolic paper-and-pencil
operations.


title:
Coherent Light Scattering from Semicontinuous Silver Nanoshells Near the
  Percolation Threshold

abstract:
  We report on measurements of visible extinction spectra of semicontinuous
silver nanoshells grown on colloidal silica spheres. We find that thin, fractal
shells below the percolation threshold exhibit geometrically tunable plasmon
resonances. A modified scaling theory approach is used to model the dielectric
response of such shells, which is then utilized to obtain the extinction cross
section in a retarded Mie scattering formalism. We show that such spherical
resonators support unique plasmon dynamics: in the visible there is a new
regime of coherently driven cluster-localized plasmons, while crossover to
homogeneous response in the infrared predicts a delocalized shell plasmon.


title: Wave scattering by metamaterial wedges and interfaces

abstract:
  We outline specific features of numerical simulations of metamaterial wedges
and interfaces. We study the effect of different positioning of a grid in the
Yee method, which is necessary to obtain consistent convergence in modeling of
interfaces with metamaterials characterized by negative dielectric permittivity
and negative magnetic permeability. We demonstrate however that, in the
framework of the continuous-medium approximation, wave scattering on the wedge
may result in a resonant excitation of surface waves with infinitely large
spatial frequencies, leading to non-convergence of the simulation results that
depend on the discretization step.


title: Advanced Optics with Laser Pointer and Metersticks

abstract:
  We are using a laser pointer as a light source, and metersticks as an optical
branch and the screen for wave optics experiments. It is shown the setup for
measurements of wavelength of laser light and rating radial spacing of the CD,
diffraction on a wire and a slit, observation of a polarization of light and
observation of a hologram.


title: On the origin of non-Gaussian statistics in hydrodynamic turbulence

abstract:
  Turbulent flows are notoriously difficult to describe and understand based on
first principles. One reason is that turbulence contains highly intermittent
bursts of vorticity and strain-rate with highly non-Gaussian statistics.
Quantitatively, intermittency is manifested in highly elongated tails in the
probability density functions of the velocity increments between pairs of
points. A long-standing open issue has been to predict the origins of
intermittency and non-Gaussian statistics from the Navier-Stokes equations.
Here we derive, from the Navier-Stokes equations, a simple nonlinear dynamical
system for the Lagrangian evolution of longitudinal and transverse velocity
increments. From this system we are able to show that the ubiquitous
non-Gaussian tails in turbulence have their origin in the inherent
self-amplification of longitudinal velocity increments, and cross amplification
of the transverse velocity increments.


title: Structural properties of screened Coulomb balls

abstract:
  Small three-dimensional strongly coupled charged particles in a spherical
confinement potential arrange themselves in a nested shell structure. By means
of experiments, computer simulations and theoretical analysis, it is shown that
their structural properties depend on the type of interparticle forces. Using
an isotropic Yukawa interaction, quantitative agreement for shell radii and
occupation is obtained.


title: Molecular orbitals and strong-field approximation

abstract:
  V.I. Usachenko and S.-I. Chu [Phys. Rev. A {\bf 71}, 063410 (2005)] discuss
the molecular strong-field approximation in the velocity gauge formulation and
indicate that some of our earlier velocity gauge calculations are inaccurate.
Here we comment on the results of Usachenko and Chu. First, we show that the
molecular orbitals used by Usachenko and Chu do not have the correct symmetry,
and second, that it is an oversimplification to describe the molecular orbitals
in terms of just a single linear combination of two atomic orbitals. Finally,
some values for the generalized Bessel function are given for comparison.


title: Extraction of the Proton Beam from the 70 GeV IHEP Accelerator

abstract:
  This paper presents the physical background for particle extraction from IHEP
accelerator using short bent silicon crystals, analyses the results of the
studies, considers in detail the regime of simultaneous work of crystal
extraction and several internal targets. It is experimentally shown that the
use of short crystals allows the extraction of beams with intensity of 10e12
proton/cycle with efficiency of 85%.


title: The hydraulic jump as a white hole

abstract:
  In the geometry of the circular hydraulic jump, the velocity of the liquid in
the interior region exceeds the speed of capillary-gravity waves (ripplons),
whose spectrum is `relativistic' in the shallow water limit. The velocity flow
is radial and outward, and thus the relativistic ripplons cannot propagating
into the interior region. In terms of the effective 2+1 dimensional
Painleve-Gullstrand metric appropriate for the propagating ripplons, the
interior region imitates the white hole. The hydraulic jump represents the
physical singularity at the white-hole horizon. The instability of the vacuum
in the ergoregion inside the circular hydraulic jump and its observation in
recent experiments on superfluid 4He by E. Rolley, C. Guthmann, M.S. Pettersen
and C. Chevallier in physics/0508200 are discussed.

categories: physics.flu-dyn cond-mat.soft gr-qc hep-ph physics.gen-ph


title:
Comment on "Roentgen quantum phase shift: a semiclassical local
  electrodynamical effect?"

abstract: In this short note we amplify our comments on the paper PRL 95,010405 (2005).


title: Ultracold neutral plasma expansion in two dimensions

abstract:
  We extend an isothermal thermal model of ultracold neutral plasma expansion
to systems without spherical symmetry, and use this model to interpret new
fluorescence measurements on these plasmas. By assuming a self-similar
expansion, it is possible to solve the fluid equations analytically and to
include velocity effects to predict the fluorescence signals. In spite of the
simplicity of this approach, the model reproduces the major features of the
experimental data.


title: Waiting-time distribution for a stock-market index

abstract:
  We investigate the waiting-time distribution of the absolute return in the
Korean stock-market index KOSPI. We define the waiting time as a time interval
during which the normalized absolute return remains continuously below a
threshold $r_c$. Through an exponential bin plot, we observe that the
waiting-time distribution shows power-law behavior, $p_f (t) \sim t^{-\beta}$,
for a range of threshold values. The waiting-time distribution has two scaling
regimes, separated by the crossover time $t_c \approx 200$ min. The power-law
exponents of the waiting-time distribution decrease when the return time
$\Delta t$ increases. In the late-time regime, $t > t_c$, the power-law
exponents are independent of the threshold to within the error bars for fixed
return time.


title: Magnetofluid Unification in the Yang-Mills Lagrangian

abstract:
  The Yang-Mills magnetofluid unification is constructed using lagrangian
approach by imposing certain gauge symmetry to the matter inside the fluid. The
model provides a general description for relativistic fluid interacting with
Abelian or non-Abelian gauge field. The differences with the hybrid
magnetofluid model are discussed, and few physical consequences of this
formalism are worked out.


title: Does the scale-free topology favor the emergence of cooperation?

abstract:
  In a recent Letter [F.C. Santos and J. M. Pacheco Phys. Rev. Lett.
\textbf{95}, 098104 (2005)], the scale-free networks are found to be
advantageous for the emergence of cooperation. In the present work an
evolutionary prisoner's dilemma game with players located on Barab\'asi-Albert
scale-free networks is studied in detail. The players are pure strategist and
can follow two strategies: either to defect or to cooperate. Serval alternative
update rules determining the evolution of each player's strategy are
considered. Using systematic Monte Carlo simulations we have calculated the
average density of cooperators as a function of the temptation to defect. It is
shown that the results obtained by numerical experiments depend strongly on the
dynamics of the game, which could lower the important of scale-free topology on
the persistence of the cooperation. Particularly, the system exhibits a phase
transition, from active state (coexistence of cooperators and defectors) to
absorbing state (only defectors surviving) when allowing `` worse\rq\rq
strategy to be imitated in the evolution of the game.


title: Mass Patterns in the Fermion Spectrum

abstract:
  All of the known fermions fit a simple formula which is presented here. The
simple formula appears to indicate a topological origin to mass generation, and
it is globally accurate to an approximate percent. Instantons or a quantized
two Higgs mechanism, as in the MSSM model, could give a simple origin to the
masses.


title:
Understanding widely scattered traffic flows, the capacity drop,
  platoons, and times-to-collision as effects of variance-driven time gaps

abstract:
  We investigate the adaptation of the time headways in car-following models as
a function of the local velocity variance, which is a measure of the
inhomogeneity of traffic flow. We apply this mechanism to several car-following
models and simulate traffic breakdowns in open systems with an on-ramp as
bottleneck. Single-vehicle data generated by several 'virtual detectors' show a
semi-quantitative agreement with microscopic data from the Dutch freeway A9.
This includes the observed distributions of the net time headways and
times-to-collision for free and congested traffic. While the times-to-collision
show a nearly universal distribution in free and congested traffic, the modal
value of the time headway distribution is shifted by a factor of about two in
congested conditions. Macroscopically, this corresponds to the 'capacity drop'
at the transition from free to congested traffic. Finally, we explain the wide
scattering of one-minute flow-density data by a self-organized variance-driven
process that leads to the spontaneous formation and decay of long-lived
platoons even for deterministic dynamics on a single lane.


title:
The Effects of Temperature, Humidity and Barometric Pressure on Short
  Sprint Race Times

abstract:
  A numerical model of 100 m and 200 m world class sprinting performances is
modified using standard hydrodynamic principles to include effects of air
temperature, pressure, and humidity levels on aerodynamic drag. The magnitude
of the effects are found to be dependent on wind speed. This implies that
differing atmospheric conditions can yield slightly different corrections for
the same wind gauge reading. In the absence of wind, temperature is found to
induce the largest variation in times (0.01 s per $10\dc$ increment in the 100
m), while relative humidity contributes the least (under 0.01 s for all
realistic conditions for 100 m). Barometric pressure variations at a particular
venue can also introduce fluctuations in performance times on the order of a
0.01 s for this race. The combination of all three variables is essentially
additive, and is more important for head-wind conditions that for tail-winds.
As expected, calculated corrections in the 200 m are magnified due to the
longer duration of the race. The overall effects of these factors on sprint
times can be considered a ``second order'' adjustment to previous methods which
rely strictly on a venue's physical elevation, but can become important in
extreme conditions.


title: Through Einstein's Eyes

abstract:
  We have developed a relativistically-accurate computer graphics code and have
used it to produce photo-realistic images and videos of scenes where special
relativistic effects dominate, either in astrophysical contexts or in imaginary
worlds where the speed of light is only a few metres per second. The videos
have been integrated into our under-graduate teaching programme for several
years. Recently we took the next step, encouraging undergraduate students to
use the code to explore relativity, develop their own videos, and eventually
package them together into Through Einstein's Eyes, a multimedia CD.


title: Passive Lorentz transformations with spacetime algebra

abstract:
  In special relativity, spacetime algebra (STA) provides a powerful and
insightful approach to an invariant formulation of physics. However, in this
geometric algebra of spacetime, relativistic physics is usually considered a
misnomer: STA provides us with an invariant (coordinate-free) formulation and
hence it seems that (passive) Lorentz transformations are misplaced. However,
in order to interpret experimental results, it is important to relate invariant
physical quantities to some reference frame. In this paper, passive Lorentz
transformations are derived using STA but without the second postulate on the
speed of light used by Einstein. This derivation sheds light on the physical
background of STA and, at the same time, clarifies Lorentz transformations in
the proper setting of (Minkowski) four-dimensional spacetime.


title:
Sensitivity of ray dynamics in an underwater sound channel to vertical
  scale of longitudinal sound-speed variations

abstract:
  We investigate sound ray propagation in a range-dependent underwater acoustic
waveguide. Our attention is focused on sensitivity of ray dynamics to the
vertical structure of a sound-speed perturbation induced by ocean internal
waves. Two models of longitudinal sound-speed variations are considered: a
periodic inhomogeneity and a stochastic one. It is found that vertical
oscillations of a sound-speed perturbation can affect rays in a resonant
manner. Such resonances give rise to chaos in certain regions of phase space.
It is shown that stability of steep rays, being observed in experiments, is
connected with suppression of resonances in the case of small-scale vertical
sound-speed oscillations.


title: Experimental Study of the Laser Diode Pumped Rubidium Maser

abstract:
  We report the operation of a $^{87}$Rb maser in the self-oscillating mode,
using a laser diode as the optical pumping source. The maser uses a TE$_{021}$
cavity surrounding a cell containing the atoms and 11 Torr of N$_{2}$ as the
buffer gas. The optical pumping is accomplished by using a commercial laser
diode frequency-locked on the linear absorption line of an external rubidium
cell. The maser output power is maximized when the laser spectrum is spread by
modulating its frequency through the variation of its injection current. The
maser output power is also presented for various modulation waveforms and
frequencies. We find that the spurious sidebands induced by the modulation can
be minimized. Finally, the linear dependence between the laser and maser
frequencies is shown. We find that the relative maser frequency pulling from
the laser is about $4.6 \times 10^{-3}$.


title: Abrupt structural transitions involving functionally optimal networks

abstract:
  We show analytically that abrupt structural transitions can arise in
functionally optimal networks, driven by small changes in the level of
transport congestion. Our findings are based on an exactly solvable model
system which mimics a variety of biological and social networks. Our results
offer an explanation as to why such diverse sets of network structures arise in
Nature (e.g. fungi) under essentially the same environmental conditions. As a
by-product of this work, we introduce a novel renormalization scheme involving
`cost motifs' which describes analytically the average shortest path across
multiple-ring-and-hub networks.

categories: physics.soc-ph cond-mat.other cond-mat.soft q-bio.OT


title: Competition of Languages and their Hamming Distance

abstract:
  We consider the spreading and competition of languages that are spoken by a
population of individuals. The individuals can change their mother tongue
during their lifespan, pass on their language to their offspring and finally
die. The languages are described by bitstrings, their mutual difference is
expressed in terms of their Hamming distance. Language evolution is determined
by mutation and adaptation rates. In particular we consider the case where the
replacement of a language by another one is determined by their mutual Hamming
distance. As a function of the mutation rate we find a sharp transition between
a scenario with one dominant language and fragmentation into many language
clusters. The transition is also reflected in the Hamming distance between the
two languages with the largest and second to largest number of speakers. We
also consider the case where the population is localized on a square lattice
and the interaction of individuals is restricted to a certain geometrical
domain. Here it is again the Hamming distance that plays an essential role in
the final fate of a language of either surviving or being extinct.


title: Propagation of Light in Photonic Crystal Fibre Devices

abstract:
  We describe a semi-analytical approach for three-dimensional analysis of
photonic crystal fibre devices. The approach relies on modal transmission-line
theory. We offer two examples illustrating the utilization of this approach in
photonic crystal fibres: the verification of the coupling action in a photonic
crystal fibre coupler and the modal reflectivity in a photonic crystal fibre
distributed Bragg reflector.


title: Plane electromagnetic wave in PEMC

abstract:
  Plane electromagnetic wave propagating in perfect electromagnetic conductor
(PEMC) is considered. Its wave number has no connection with the frequency. An
interface is introduced between an ordinary isotropic medium and PEMC. The wave
in PEMC is matched to plane electromagnetic wave incident normally on the
interface from the ordinary medium and reflected from it. Then the
plane-parallel slab made of PEMC is considered and a plane wave is found in it.


title: Laser-dressed vacuum polarization in a Coulomb field

abstract:
  We investigate quantum electrodynamic effects under the influence of an
external, time-dependent electromagnetic field, which mediates dynamic
modifications of the radiative corrections. Specifically, we consider the
quantum electrodynamic vacuum-polarization tensor under the influence of two
external background fields: a strong laser field and a nuclear Coulomb field.
We calculate the charge and current densities induced by a nuclear Coulomb
field in the presence of a laser field. We find the corresponding induced
scalar and vector potentials. The induced potential, in first-order
perturbation theory, leads to a correction to atomic energy levels. The
external laser field breaks the rotational symmetry of the system.
Consequently, the induced charge density is not spherically symmetric, and the
energy correction therefore leads to a "polarized Lamb shift." In particular,
the laser generates an additional potential with a quadrupole moment. The
corresponding laser-dressed vacuum-polarization potential behaves like 1/r**3
at large distances, unlike the Uehling potential that vanishes exponentially
for large r. Our investigation might be useful for other situations where
quantum field theoretic phenomena are subjected to external fields of a rather
involved structure.


title:
Uncovering collective listening habits and music genres in bipartite
  networks

abstract:
  In this paper, we analyze web-downloaded data on people sharing their music
library, that we use as their individual musical signatures (IMS). The system
is represented by a bipartite network, nodes being the music groups and the
listeners. Music groups audience size behaves like a power law, but the
individual music library size is an exponential with deviations at small
values. In order to extract structures from the network, we focus on
correlation matrices, that we filter by removing the least correlated links.
This percolation idea-based method reveals the emergence of social communities
and music genres, that are visualised by a branching representation. Evidence
of collective listening habits that do not fit the neat usual genres defined by
the music industry indicates an alternative way of classifying listeners/music
groups. The structure of the network is also studied by a more refined method,
based upon a random walk exploration of its properties. Finally, a personal
identification - community imitation model (PICI) for growing bipartite
networks is outlined, following Potts ingredients. Simulation results do
reproduce quite well the empirical data.


title: From sand to networks: a study of multi-disciplinarity

abstract:
  In this paper, we study empirically co-authorship networks of neighbouring
scientific disciplines, and describe the system by two coupled networks. By
considering a large time window, we focus on the properties of the interface
between the disciplines. We also focus on the time evolution of the
co-authorship network, and highlight a rich phenomenology including first order
transition and cluster bouncing and merging. Finally, we present a ferro-
electric-like model (CDIM), involving bond redistribution between the nodes,
that reproduces qualitatively the structuring of the system in homogeneous
phases


title:
Classification of dispersion equations for homogeneous
  dielectric-magnetic uniaxial materials

abstract:
  The geometric representation at a fixed frequency of the wavevector (or
dispersion) surface $\omega(\vec k)$ for lossless, homogeneous
dielectric--magnetic uniaxial materials is explored, when the elements of the
relative permittivity and permeability tensors of the material can have any
sign. Electromagnetic plane waves propagating inside the material can exhibit
dispersion surfaces in the form of ellipsoids of revolution, hyperboloids of
one sheet, or hyperboloids of two sheets. Furthermore, depending on the
relative orientation of the optic axis, the intersections of these surfaces
with fixed planes of propagation can be circles, ellipses, hyperbolas, or
straight lines. The obtained understanding is used to study the reflection and
refraction of electromagnetic plane waves due to a planar interface with an
isotropic medium.


title: Stability of Quantum Fluids : Wavy Interface Effect

abstract:
  A numerical investigation for the stability of the incompressible slip flow
of normal quantum fluids (above the critical phase transition temperature)
inside a microslab where surface acoustic waves propagate along the walls is
presented. Governing equations and associated slip velocity and wavy interface
boundary conditions for the flow of normal fluids confined between elastic wavy
interfaces are obtained. The numerical approach is an extension (with a complex
matrix pre-conditioning) of the spectral method. We found that the critical
Reynolds number ($Re_{cr}$ or the critical velocity) decreases significantly
once the slip velocity and wavy interface effects are present and the latter is
dominated ($Re_{cr}$ mainly depends on the wavy interfaces).


title: Albert Einstein as the father of solid state physics

abstract:
  Einstein is usually revered as the father of special and general relativity.
In this article I demonstrate that he is also the father of Solid State
Physics, or even his broader version known as Condensed Matter Physics
(including liquids). His 1907 article on the specific heat of solids
introduces, for the first time, the effect of lattice vibrations on the
thermodynamic properties of crystals, in particular the specific heat. His 1905
article on the photoelectric effect and photoluminescence opened the fields of
photoelectron spectroscopy and photoluminescence spectroscopy. Other important
achievements include Bose-Einstein condensation and the Einstein relation
between the difussion coefficient an mobility. In this article I discuss
Einstein's papers relevant to these topics and their relevance to modern day
condensed matter physics.


title: Optimizing at the Ergodic Edge

abstract:
  Using a simple, annealed model, some of the key features of the recently
introduced extremal optimization heuristic are demonstrated. In particular, it
is shown that the dynamics of local search possesses a generic critical point
under the variation of its sole parameter, separating phases of too greedy
(non-ergodic, jammed) and too random (ergodic) exploration. Comparison of
various local search methods within this model suggests that the existence of
the critical point is essential for the optimal performance of the heuristic.


title: Ultrafast Deflection of Spatial Solitons in AlGaAs Slab Waveguides

abstract:
  We demonstrate ultrafast all-optical deflection of spatial solitons in an
AlGaAs slab waveguide using 190 fs, 1550 nm pulses which are used to generate
and deflect the spatial soliton. The steering beam is focused onto the top of
the waveguide near the soliton pathway and the soliton is steered due to
refractive index changes induced by optical Kerr, or free carrier (Drude)
effects. Angular deflections up to 8 mR are observed.


title:
Evidence of catalytic production of hot hydrogen in rf generated
  hydrogen/argon plasmas

abstract:
  In this paper the selective broadening of the atomic hydrogen lines in pure
H2 and Ar/H2 mixtures in a large 'GEC' cell (36 cm length_ 14 cm ID) was mapped
as a function of position, H2/Ar ratio, time, power, and pressure. Several
observations regarding the selective line broadening were particularly notable
as they are unanticipated on the basis of earlier models. First, the anomalous
broadening of the Balmer lines was found to exist throughout the plasma, and
not just in the region between the electrodes. Second, the broadening was
consistently a complex function of the operating parameters particularly gas
composition (highest in pure H2), position, power, time and pressure. Clearly
not anticipated by earlier models were the findings that under some conditions
the highest concentration of 'hot' (>10 eV) hydrogen was found at the entry
end, and not in the high field region between the electrodes and that in other
conditions, the hottest H was at the (exit) pump (also grounded electrode) end.
Third, excitation and electron temperatures were less than one eV in all
regions of the plasma not directly adjacent (>1mm) to the electrodes, providing
additional evidence that the energy for broadening, contrary to standard
models, is not obtained from the field. Fourth, in contrast to our earlier
studies of hydrogen/helium and water plasmas, we found that in some conditions
98% of the atomic hydrogen was in the 'hot' state throughout the GEC-type cell.
Virtually every operating parameter studied impacted the character of the hot H
atom population, and clearly second and third order effects exist, indicating a
need for experimental design. Some non-field mechanisms for generating hot
hydrogen atoms, specifically those suggested by Mills' CQM model, are outlined.


title: Eulerian Derivation of the Coriolis Force

abstract:
  In textbooks of geophysical fluid dynamics, the Coriolis force and the
centrifugal force in a rotating fluid system are derived by making use of the
fluid parcel concept. In contrast to this intuitive derivation to the apparent
forces, more rigorous derivation would be useful not only for the pedagogical
purpose, but also for the applications to other kinds of rotating geophysical
systems rather than the fluid. The purpose of this paper is to show a general
procedure to derive the transformed equations in the rotating frame of
reference based on the local Galilean transformation and rotational coordinate
transformation of field quantities. The generality and usefulness of this
Eulerian approach is demonstrated in the derivation of apparent forces in
rotating fluids as well as the transformed electromagnetic field equation in
the rotating system.


title: Transition Wake-Fields in Resistive Tube

abstract:
  The transition wake fields excited by relativistic point charge in
cylindrical resistive round pipe are studied. The problem has been solved for
the infinite pipe with abrupt change of the walls conductivity from perfect
boundary condition to resistive. The analytical presentation of the
longitudinal monopole wake field is given.


title: Numerical modeling of quasiplanar giant water waves

abstract:
  In this work we present a further analytical development and a numerical
implementation of the recently suggested theoretical model for highly nonlinear
potential long-crested water waves, where weak three-dimensional effects are
included as small corrections to exact two-dimensional equations written in the
conformal variables [V.P. Ruban, Phys. Rev. E 71, 055303(R) (2005)]. Numerical
experiments based on this theory describe the spontaneous formation of a single
weakly three-dimensional large-amplitude wave (alternatively called freak,
killer, rogue or giant wave) on the deep water.


title:
The repository of physical models used for the CODATA-2002 FPC
  (re-)evaluation

abstract:
  We present PAREVAL package containing a repository of theoretical physical
models used for (re-)evaluation of the fundamental physical constants (FPC). It
holds all necessary data for building 105 (so called) observational equations
and can be used in high precision calculations. Among repository models there
are expressions for energy levels of hydrogen and deuterium (with 16 types of
contributions), electron and muon magnetic moment anomalies, muonium
ground-state hyperfine splitting, Zeeman energy levels in muonium. Each model
is represented as {\sl Mathematica} module with XML meta-data keeping
information about the model (including data on dependence from others models).
There are also modules for working with the basic FPC.


title: A General Theory of Goodness of Fit in Likelihood Fits

abstract:
  Maximum likelihood fits to data can be performed using binned data and
unbinned data. The likelihood fits in either case produce only the fitted
quantities but not the goodness of fit. With binned data, one can obtain a
measure of the goodness of fit by using the $\chi^2$ method, after the maximum
likelihood fitting is performed. With unbinned data, currently, the fitted
parameters are obtained but no measure of goodness of fit is available. This
remains, to date, an unsolved problem in statistics. By considering the
transformation properties of likelihood functions with respect to change of
variable, we conclude that the likelihood ratio of the theoretically predicted
probability density to that of {\it the data density} is invariant under change
of variable and provides the goodness of fit. We show how to apply this
likelihood ratio for binned as well as unbinned likelihoods and show that even
the $\chi^2$ test is a special case of this general theory. In order to
calculate errors in the fitted quantities, we need to solve the problem of
inverse probabilities. We use Bayes' theorem to do this, using the data density
obtained in the goodness of fit. This permits one to invert the probabilities
without the use of a Bayesian prior. The resulting statistics is consistent
with frequentist ideas.


title: Equilibrium Conditions for the Floating of Multiple Interfacial Objects

abstract:
  We study the effect of interactions between objects floating at fluid
interfaces, for the case in which the objects are primarily supported by
surface tension. We give conditions on the density and size of these objects
for equilibrium to be possible and show that two objects that float when
well-separated may sink as the separation between the objects is decreased.
Finally, we examine the equilbrium of a raft of strips floating at an
interface, and find that rafts of sufficiently low density may have infinite
spatial extent, but that above a critical raft density, all rafts sink if they
are sufficiently large. We compare our numerical and asymptotic results with
some simple table-top experiments, and find good quantitative agreement.


title: Experiments on Internet Response

abstract:
  This paper suggests a generalized distribution of response times to new
information $\sim t^{-b}$ for human populations in the absence of deadlines.
This has important implications for psychological and social studies as well
the study of dynamical networks such as the WWW.


title: Quantum mechanics in curved space-time II

abstract:
  This paper is a sequence of the work presented in [1], where, the principles
of the general relativity have been used to formulate quantum wave equations
taking into account the effect of the electromagnetic and strong interactions
in the space-time metric of quantum systems. Now, the role of the
energy-momentum tensor in this theory is studied, and it is consistent with the
formulation of the general quantum mechanics shown in [1]. With this procedure,
a dynamical cut-off is generated and the constant $A$ of the field equation is
calculated.


title:
Lorentz, Edwards transformations and the principle of permutation
  invariance

abstract:
  The Lorentz transformation is derived without the postulate of the universal
limiting speed, and the general Edwards transformation is obtained by using the
principle of permutation invariance (covariance). It is shown that the
existences of the one-way universal limiting speed (in the Lorentz
transformation) and the constancy of the two-way average speed of light (in the
Edwards transformation) are the necessary consequences of the principle of
permutation invariance that is consistent with the postulate of relativity. The
connection between the Edward transformation and the general coordinate
transformation is discussed, and based on this, we find that the physical
meaning of the Edward parameter, which indicates the anisotropy of the speed of
light, is a gravitomagnetic potential of the spacetime.


title: Properties of trapped electromagnetic modes in coupled waveguides

abstract:
  The existence of trapped modes in coupled electromagnetic waveguides is
experimentally investigated for configurations with different degrees of
symmetry supporting hybrid modes. The occurrence of confined solutions in such
open geometries is proven to be much more general than demonstrated so far, as
predicted by Goldstone and Jaffe [J. Goldstone and R. L. Jaffe, Phys. Rev. B
45, 14100 (1992)]. The identification of the observed modes is based on the
numerical modeling of the relative vector fields. The experimental results
evidence as an increasing aperture of the configuration can improve the
confinement of the mode instead of generating additional leakage channels. In
particular, long-lived trapped modes can be easily obtained in geometries with
a relevant degree of aperture. Their resonance parameters can compete with
those of standard close cavities working at millimeter wavelengths. The role of
the symmetry on the properties of these trapped modes is discussed in detail.


title: Transfer Entropy Analysis of the Stock Market

abstract:
  In terms of transfer entropy, we investigated the strength and the direction
of information transfer in the US stock market. Through the directionality of
the information transfer, the more influential company between the correlated
ones can be found and also the market leading companies are selected. Our
entropy analysis shows that the companies related with energy industries such
as oil, gas, and electricity influence the whole market.


title: X-Ray Source Based on the Parametric X-Rays

abstract:
  Prospects of parametric x-rays (PXR) application for the development of a
tuneable quasi-monochromatic x-ray source for medical imaging are discussed.
Analysis of basic requirements for electron accelerator shows that it must be
relatively low-energy and high-current linac. In comparison with known
ultra-relativistic cases, at low energies PXR properties will be modified to a
great extent by multiple scattering of the electrons. PXR intensity dependence
on target thickness and beam energy are calculated taking multiple scattering
into account. It is concluded that PXR source based on real medical
accelerators is feasible and can provide x-ray flux needful for obtaining high
quality medical images.


title: Design of a Polarised Positron Source Based on Laser Compton Scattering

abstract:
  We describe a scheme for producing polarised positrons at the ILC from
polarised X-rays created by Compton scattering of a few-GeV electron beam off a
CO2 or YAG laser. This scheme is very energy effective using high finesse laser
cavities in conjunction with an electron storage ring.


title:
The cosmic quanta paradigm fulfils the relativistic mechanics, improves
  the gravitation theory and originates the nuclear forces

abstract:
  Changing an obsolet physical paradigm, such as the gravitational mass,
consents to explain the inertia-gravitation phenomena and the origin of the
nuclear forces.


title:
Phase transition in a sexual age-structured model of learning foreign
  languages

abstract:
  The understanding of language competition helps us to predict extinction and
survival of languages spoken by minorities. A simple agent-based model of a
sexual population, based on the Penna model, is built in order to find out
under which circumstances one language dominates other ones. This model
considers that only young people learn foreign languages. The simulations show
a first order phase transition where the ratio between the number of speakers
of different languages is the order parameter and the mutation rate is the
control one.


title: Spectral energy dynamics in magnetohydrodynamic turbulence

abstract:
  Spectral direct numerical simulations of incompressible MHD turbulence at a
resolution of up to $1024^3$ collocation points are presented for a
statistically isotropic system as well as for a setup with an imposed strong
mean magnetic field. The spectra of residual energy,
$E_k^\mathrm{R}=|E_k^\mathrm{M}-E_k^\mathrm{K}|$, and total energy,
$E_k=E^\mathrm{K}_k+E^\mathrm{M}_k$, are observed to scale self-similarly in
the inertial range as $E_k^\mathrm{R}\sim k^{-7/3}$, $E_k\sim k^{-5/3}$
(isotropic case) and $E^\mathrm{R}_{k_\perp}\sim k_\perp^{-2}$,
$E_{k_\perp}\sim k_\perp^{-3/2}$ (anisotropic case, perpendicular to the mean
field direction). A model of dynamic equilibrium between kinetic and magnetic
energy, based on the corresponding evolution equations of the eddy-damped
quasi-normal Markovian (EDQNM) closure approximation, explains the findings.
The assumed interplay of turbulent dynamo and Alfv\'en effect yields
$E_k^\mathrm{R}\sim k E^2_k$ which is confirmed by the simulations.


title: Potentials of Unbalanced Complex Kinetics Observed in Market Time Series

abstract:
  As a model of market price, we introduce a new type of random walk in a
moving potential which is approximated by a quadratic function with its center
given by the moving average of its own trace. The properties of resulting
random walks are similar to those of ordinary random walks for large time
scales; however, their short time properties are approximated by abnormal
diffusion with non-trivial exponents. A new data analysis method based on this
model enables us to observe temporal changes of potential forces from high
precision market data directly.


title: Steady Motion of a Rigid Disk of Finite Thickness on a Horizontal Plane

abstract:
  The article discusses the steady motion of a rigid disk of finite thickness
rolling on its edge on a horizontal plane under the influence of gravity. The
governing equations are presented and two cases allowing for a steady state
solution are considered: rolling on consistently rough ground and rolling on
perfectly smooth ground. The conditions of steady motion are derived for both
kinds of ground and it is shown that the possible steady motion of a disk is
either on a straight line in a circle. Also oscillations about steady state are
discussed and conditions for stable motion are established.


title:
Correlation between the parameters of the rate equation for simple
  aftershock sequences: implications for the forecasting of rates and
  probabilities

abstract:
  We analyzed the correlations among the parameters of the Reasenberg and Jones
(1989) formula describing the aftershock rate after a mainshock as a function
of time and magnitude, on the basis of parameter estimates made in previous
works for New Zealand, Italy and California. For all of three datasets we found
that the magnitude-independent productivity a is significantly correlated with
the b-value of the Gutenberg-Richter law and, in some cases, with parameters p
and c of the modified Omori's law. We argued that the correlation between a and
b can be ascribed to an inappropriate definition of the coefficient of
mainshock magnitude as the correlation becomes insignificant if the latter is
assumed to be $\alpha\simeq$ 2/3b rather than b. This interpretation well
agrees with the results of direct a estimates we made, by an epidemic type
model (ETAS), from the data of some large Italian sequences. We also verified
that assuming $\alpha$ about 2/3 of the average b value estimated from Italian
sequences occurred in the time interval 1981-1996 improves the ability to
predict the behavior of most recent sequences (from 1997 to 2003). Our results
indicate a partial inadequacy of the original Reasenberg and Jones (1989)
formulation when used to forecast the productivity of future sequences. In
particular, the aftershock rates and probabilities tend to be overestimated for
stronger mainshocks and conversely underestimated for weaker ones.


title:
The Large Analog Bandwidth Recorder And Digitizer with Ordered Readout
  (LABRADOR) ASIC

abstract:
  Three generations of full-custom analog integrated circuits designed for
low-power, high-speed sampling of Radio-Frequency (RF) transients in excess of
the Nyquist minimum have been developed. These 0.25$\mu m$ CMOS devices are
denoted the Large Analog Bandwidth Recorder and Digitizer with Ordered Readout
(LABRADOR) ASICs and finally consist of 9 channels of 260 deep sampling.
Continuous sampling is provided with common stop capability. Input analog
bandwidth is approximately 1GHz and sampling speeds are adjustable from 0.02 to
3.7GSa/s. Completely parallel internal conversion supports 12-bit digitization
and readout of all 2340 cells in under 50$\mu s$.


title:
Statistical modelling of tropical cyclone tracks: modelling the
  autocorrelation in track shape

abstract:
  We describe results from the third stage of a project to build a statistical
model for hurricane tracks. In the first stage we modelled the unconditional
mean track. In the second stage we modelled the unconditional variance of
fluctuations around the mean. Now we address the question of how to model the
autocorrelations in the standardised fluctuations. We perform a thorough
diagnostic analysis of these fluctuations, and fit a type of AR(1) model. We
then assess the goodness of fit of this model in a number of ways, including an
out-of-sample comparison with a simpler model, an in-sample residual analysis,
and a comparison of simulated tracks from the model with the observed tracks.
Broadly speaking, the model captures the behaviour of observed hurricane
tracks. In detail, however, there are a number of systematic errors.


title:
Physics of Transport and Traffic Phenomena in Biology: from molecular
  motors and cells 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
quantitaive 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: The Planck Scale Underpinning for Space Time

abstract:
  We provide a rationale for the Planck scale being the minimum scale in the
universe, as also its specific numerical values. In the process we answer the
question of why the Planck scale is $10^{20}$ times the Compton scale of
elementary particles. These considerations show how the Planck scale provides
an underpinning for space time.


title: Explicit Generation of Integer Solutions via CY Mfds

abstract:
  Metrics on Calabi-Yau manifolds are used to derive a formula that finds the
existence of integer solutions to polynomials. These metrics are derived from
an associated algebraic curve, together with its anti-holomorphic counterpart.
The integer points in the curve coincide with points on the manifold, and the
metric form around these points are used to find their existence. The explicit
form of the metrics can be found through a solution to the D-terms in a
non-linear sigma model.


title: Total absorption of an electromagnetic wave by an overdense plasma

abstract:
  We show both theoretically and experimentally that an electromagnetic wave
can be totally absorbed by an overdense plasma when a subwavelength diffraction
grating is placed in front of the plasma surface. The absorption is due to
dissipation of surface plasma waves (plasmons-polaritons) that have been
resonantly excited by the evanescent component of the diffracted
electromagnetic wave. The developed theoretical model allows one to determine
the conditions for the total absorption.


title:
Grazing-angle scattering of electromagnetic waves in gratings with
  varying mean parameters: grating eigenmodes

abstract:
  A highly unusual pattern of strong multiple resonances for bulk
electromagnetic waves is predicted and analysed numerically in thick periodic
holographic gratings in a slab with the mean permittivity that is larger than
that of the surrounding media. This pattern is shown to exist in the geometry
of grazing-angle scattering (GAS), that is when the scattered wave (+1
diffracted order) in the slab propagates almost parallel to the slab (grating)
boundaries. The predicted resonances are demonstrated to be unrelated to
resonant generation of the conventional guided modes of the slab. Their
physical explanation is associated with resonant generation of a completely new
type of eigenmodes in a thick slab with a periodic grating. These new slab
eigenmodes are generically related to the grating; they do not exist if the
grating amplitude is zero. The field structure of these eigenmodes and their
dependence on structural and wave parameters is analysed. The results are
extended to the case of GAS of guided modes in a slab with a periodic groove
array of small corrugation amplitude and small variations in the mean thickness
of the slab at the array boundaries.


title:
Anomalous absorption of bulk shear sagittal acoustic waves in a layered
  structure with viscous fluid

abstract:
  It is demonstrated theoretically that the absorptivity of bulk shear sagittal
waves by an ultra-thin layer of viscous fluid between two different elastic
media has a strong maximum (in some cases as good as 100%) at an optimal layer
thickness. This thickness is usually much smaller than the penetration depths
and lengths of transverse and longitudinal waves in the fluid. The angular
dependencies of the absorptivity are demonstrated to have significant and
unusual structure near critical angles of incidence. The effect of
non-Newtonian properties and non-uniformities of the fluid layer on the
absorptivity is also investigated. In particular, it is shown that the
absorption in a thin layer of viscous fluid is much more sensitive to non-zero
relaxation time(s) in the fluid layer than the absorption at an isolated
solid-fluid interface.


title:
Observation of Fluorescence Emissions from Single-Bubble
  Sonoluminescence in Water doped with Quinine

abstract:
  Sonoluminescence is a phenomenon involving the transduction of sound into
light. The detailed mechanism as well as the energy-focusing potentials are not
yet fully explored and understood. So far only optical photons are observed,
while emissions in the ultra-violet range are only inferred. By doping the
fluorescent dye quinine into water with dilute sulphuric acid, the high energy
photons can be converted into the optical photons with slower decay constants.
These sonoluminescence and fluorescent emissions were observed in coincidence,
and the emitted signals of the two modes can be differentiated by their
respective timing profiles. Plans for using this technique as a diagnostic tool
to quantitatively study ultra-violet and other high energy emissions in
sonoluminescence are discussed.


title:
Relativistic correlation correction to the binding energies of the
  ground configuration of Beryllium-like, Neon-like, Magnesium-like and
  Argon-like ions

abstract:
  Total electronic correlation correction to the binding energies of the
isoelectronic series of Beryllium, Neon, Magnesium and Argon, are calculated in
the framework of relativistic multiconfiguration Dirac-Fock method. Convergence
of the correlation energies is studied as the active set of orbitals is
increased. The Breit interaction is treated fully self-consistently. The final
results can be used in the accurately determination of atomic masses from
highly charged ions data obtained in Penning-trap experiments.


title:
Use of coated silicon field emitters as neutralisers for fundamental
  physics missions in space

abstract:
  Spacecraft neutralisers are required as part of the ion propulsion system for
accurate station keeping in fundamental physics missions. This paper describes
the use of thin layers of insulating materials as coatings for the gated
silicon field emitter array structure used in a spacecraft neutraliser. These
thin coatings are postulated to reduce power consumption and reduce
overheating. The power consumption and lifetime of aluminium nitride and
amorphous hydrogenated diamond-like carbon coatings have been tested by
current-voltage and endurance tests. Diamond-like carbon coatings were
promising, performing better in endurance tests than uncoated samples, but
further work is required to characterise the coating's physical properties and
its effects on field emission. The thermal conductivity of the coating material
had little effect on measured sample lifetimes. Aluminium nitride had reduced
power consumption compared to diamond-like carbon coated and uncoated samples.
A thin (~5 nm) layer of aluminium nitride was found to be optimal, meeting
European Space Agency specifications for the neutraliser engineering model.


title:
An Analytical Solution of the Equations of a Rolling Disk of Finite
  Thickness on a Rough Plane

abstract:
  In this article an analytical solution of equations of motion of a rigid disk
of finite thickness rolling on its edge on a perfectly rough horizontal plane
under the action of gravity is given. The solution is given in terms of Gauss
hypergeometrical functions.


title:
Lattice Boltzmann simulations of apparent slip in hydrophobic
  microchannels

abstract:
  Various experiments have found a boundary slip in hydrophobic microchannel
flows, but a consistent understanding of the results is still lacking. While
Molecular Dynamics (MD) simulations cannot reach the low shear rates and large
system sizes of the experiments, it is often impossible to resolve the needed
details with macroscopic approaches. We model the interaction between
hydrophobic channel walls and a fluid by means of a multi-phase lattice
Boltzmann model. Our mesoscopic approach overcomes the limitations of MD
simulations and can reach the small flow velocities of known experiments. We
reproduce results from experiments at small Knudsen numbers and other
simulations, namely an increase of slip with increasing liquid-solid
interactions, the slip being independent of the flow velocity, and a decreasing
slip with increasing bulk pressure. Within our model we develop a semi-analytic
approximation of the dependence of the slip on the pressure.


title: Perfect antireflection via negative refraction

abstract:
  We suggest a geometrical framework to discuss the action of slabs of
negatively refracting materials. We show that these slabs generate the same
orbits as normal materials, but traced out in opposite directions. This
property allows us to confirm that the action of any lossless multilayer can be
optically cancelled by putting it together with the multilayer constructed as
the inverted mirror image, with $\epsilon$ and $\mu$ reversed in sign.


title: Distribution of Return Periods of Rare Events in Correlated Time Series

abstract:
  We study the effect on the distribution of return periods of rare events of
the presence in a time series of finite-term correlations with non-exponential
decay. Precisely, we analyze the auto-correlation function and the statistics
of the return intervals of extreme values of the resistance fluctuations
displayed by a resistor with granular structure in a nonequilibrium stationary
state. The resistance fluctuations, $\delta R$, are calculated by Monte Carlo
simulations using the SBRN model introduced some years ago by Pennetta,
Tref\'an and Reggiani and based on a resistor network approach. A rare event
occurs when $\delta R$ overcomes a threshold value $q$ significantly higher
than the average value of the resistance. We have found that for highly
disordered networks, when the auto-correlation function displays a
non-exponential decay but yet the resistance fluctuations are characterized by
a finite correlation time, the distribution of return intervals of the extreme
values is well described by a stretched exponential, with exponent largely
independent of the threshold $q$. We discuss this result and some of the main
open questions related to it, also in connection with very recent findings by
other authors concerning the observation of stretched exponential distributions
of return intervals of extreme events in long-term correlated time series.


title: Avoided crossings in driven systems

abstract:
  We characterize the avoided crossings in a two-parameter, time-periodic
system which has been the basis for a wide variety of experiments. By studying
these avoided crossings in the near-integrable regime, we are able to determine
scaling laws for the dependence of their characteristic features on the
non-integrability parameter. As an application of these results, the influence
of avoided crossings on dynamical tunneling is described and applied to the
recent realization of multiple-state tunneling in an experimental system.


title: The Dynamics of Viral Marketing

abstract:
  We present an analysis of a person-to-person recommendation network,
consisting of 4 million people who made 16 million recommendations on half a
million products. We observe the propagation of recommendations and the cascade
sizes, which we explain by a simple stochastic model. We analyze how user
behavior varies within user communities defined by a recommendation network.
Product purchases follow a 'long tail' where a significant share of purchases
belongs to rarely sold items. We establish how the recommendation network grows
over time and how effective it is from the viewpoint of the sender and receiver
of the recommendations. While on average recommendations are not very effective
at inducing purchases and do not spread very far, we present a model that
successfully identifies communities, product and pricing categories for which
viral marketing seems to be very effective.

categories: physics.soc-ph cond-mat.stat-mech cs.DB cs.DS


title:
Rigorous analysis of grazing-angle scattering of electromagnetic waves
  in periodic gratings

abstract:
  Grazing-angle scattering (GAS) is a type of Bragg scattering of waves in
slanted non-uniform periodic gratings, when the diffracted order satisfying the
Bragg condition propagates at a grazing angle with respect to the boundaries of
a slab-like grating. Rigorous analysis of GAS of bulk TE electromagnetic waves
is undertaken in holographic gratings by means of the enhanced T-matrix
algorithm. A comparison of the rigorous and the previously developed
approximate theories of GAS is carried out. A complex pattern of numerous
previously unknown resonances is discovered and analysed in detail for gratings
with large amplitude, for which the approximate theory fails. These resonances
are associated not only with the geometry of GAS, but are also typical for wide
transmitting gratings. Their dependence on grating amplitude, angles of
incidence and scattering, and grating width is investigated numerically.
Physical interpretation of the predicted resonances is linked to the existence
and the resonant generation of special new eigenmodes of slanted gratings. Main
properties of these modes and their field structure are discussed.


title:
Non-steady-state double-resonant extremely asymmetrical scattering of
  waves in periodic gratings

abstract:
  Double-resonant extremely asymmetrical scattering (DEAS) is a strongly
resonant type of Bragg scattering in two joint or separated uniform gratings
with different phases. It is characterised by a very strong increase of the
scattered and incident wave amplitudes inside and between the gratings at a
resonant phase shift between the gratings. DEAS is realised when the first
diffracted order satisfying the Bragg condition propagates parallel to the
grating boundaries, and the joint or separated gratings interact by means of
the diffractional divergence of the scattered waves from one grating into
another. This Letter develops a theory of non-steady-state DEAS of bulk TE
electromagnetic waves in holographic gratings, and investigates the process of
relaxation of the incident and scattered wave amplitudes to their steady-state
values inside and outside the gratings. Typical relaxation times are
determined. Physical explanation of the predicted effects is presented.


title:
Rigorous analysis of extremely asymmetrical scattering of
  electromagnetic waves in slanted periodic gratings

abstract:
  Extremely asymmetrical scattering (EAS) is a new type of Bragg scattering in
thick, slanted, periodic gratings. It is realised when the scattered wave
propagates parallel to the front boundary of the grating. Its most important
feature is the strong resonant increase in the scattered wave amplitude
compared to the amplitude of the incident wave: the smaller the grating
amplitude, the larger the amplitude of the scattered wave. In this paper,
rigorous numerical analysis of EAS is carried out by means of the enhanced
T-matrix algorithm. This includes investigation of harmonic generation inside
and outside the grating, unusually strong edge effects, fast oscillations of
the incident wave amplitude in the grating, etc. Comparison with the previously
developed approximate theory is carried out. In particular, it is demonstrated
that the applicability conditions for the two-wave approximation in the case of
EAS are noticeably more restrictive than those for the conventional Bragg
scattering. At the same time, it is shown that the approximate theory is
usually highly accurate in terms of description of EAS in the most interesting
cases of scattering with strong resonant increase of the scattered wave
amplitude. Physical explanation of the predicted effects is presented.


title: Incoherent light induced self-organization of molecules

abstract:
  Although coherent light is usually required for the self-organization of
regular spatial patterns from optical beams, we show that peculiar light matter
interaction can break this evidence. In the traditional method to record
laser-induced periodic surface structures, a light intensity distribution is
produced at the surface of a polymer film by an interference between two
coherent optical beams. We report on the self-organization followed by
propagation of a surface relief pattern. It is induced in a polymer film by
using a low-power and small-size coherent beam assisted by a high-power and
large-size incoherent and unpolarized beam. We demonstrate that we can obtain
large size and well organized patterns starting from a dissipative interaction.
Our experiments open new directions to improve optical processing systems.


title:
Comparison of metal-amino acid interaction in Phe-Ag and Tyr-Ag
  complexes by spectroscopic measurements

abstract:
  In this article, we have compared the metal-amino acid interactions in Tyr-Ag
and Phe-Ag complexes through pH dependent SERS measurements. By analyzing the
variation in relative intensities of SERS bands with the pH of the amino acid
solution, we have obtained the orientation and conformation of the amino acid
molecules on the Ag surface. The results obtained from our experimental studies
are supported by the the energy minimized strucutres and the observed charge
distributions in different terminals of the molecules. This, in a way, shows
that SERS measurements not only exhibit the interaction of the amino acid
molecules with Ag clusters but also demonstrate their orientation around it. We
have addressed a long standing query on whether the amine group is directly
attached with Ag surface along with the carboxylate group and $\pi$-electrons
in these systems. In addition, pH dependent optical absorption and transmission
electron microscopy measurements have been performed to understand the required
conditions for the appearance of the SERS spectra in the light of the
aggregation of metal particles and the number of hot sites in the sol. Our
results confirm that the formation of hot sites in the sol plays a direct role
to form a stable Ag-ligand complex. Furthermore, the interaction kinetics of
metal-amino acid complexes have been analyzed via both Raman and absorption
measurements.


title: Wealth distribution and Pareto's law in the Hungarian medieval society

abstract:
  The distribution of wealth in the Hungarian medieval aristocratic society is
reported and studied. The number of serf families belonging to a noble is taken
as a measure of the corresponding wealth. Our results reveal the power-law
nature of this distribution function, confirming the validity of the Pareto law
for such a society. The obtained Pareto index $\alpha=0.92$ is however smaller
than the values currently reported in the literature. We argue that the value
close to 1, of the Pareto index is a consequence of the absence of a relevant
economic life in the targeted society, in agreement with the prediction of
existing wealth distribution models for the idealized case of independently
acting agents. Models developed to explain city populations may also be adapted
to justify our results.


title: Entropy Bound for the Crystalline Vacuum Cosmic Space Model

abstract:
  By applying the Heisenberg's uncertainty principle for a macroscopic quantum
gas formed by gravitational waves an expression for the universal bound on the
entropy proposed by Bekenstein for any system of maximum radius R and total
energy E has been obtained. By using such expression, in the theoretical scheme
of the crystalline vacuum cosmic model, the low entropy value at the Big Bang
beginning, 1088k, is explained. According to our analysis the time arrow is
well defined and the theoretical time flow occurs only in one direction as
requested by the physical processes of gravitational stabilization of the
vacuum space crystalline structure around equilibrium conditions.
  PACS numbers: 65.50.+m, 97.60.Lf, 03.65.-w, 61.50.-f, 98.80.Ft, 04.20.-q


title:
Thermodynamics of the Transformation of Gravitational Waves into Matter
  Quantums for a Vacuum Space Model

abstract:
  It is shown that the entropy of low density monochromatic gravitational
waves, waves required for the stabilization of the crystalline structure of
vacuum cosmic space, varies with the volume in the same manner as the entropy
of an ideal gas formed by particles. This implies that close enough to the
big-bang event the energy of all the 10 to the 120 power gravitational waves,
under an adiabatic compression process, which stabilizes the crystalline
structure of vacuum space behaves thermodynamically as though it is consisted
of a number nB = 10 to the 80 power of independent energy or matter quanta
(neutrons).
  PACS numbers: 03.50.De, 03.65.-w, 04.20.-q, 61.50.-f, 65.50.+m, 98.80.Ft,
97.60.Lf


title:
An index to quantify an individual's scientific research valid across
  disciplines

abstract:
  The number h of papers with at least h citations has been proposed to
evaluate individual's scientific research production. This index is robust in
several ways but yet strongly dependent on the research field. We propose a
complementary index hI = h^2/N_t, with N_t being the total number of authors in
the considered h papers. A researcher with index hI has hI papers with at least
hI citation if he/she had published alone. We have obtained the rank plots of h
and hI for four Brazilian scientific communities. Contrasting to the h-index
curve, the hI index present a perfect data collapse into a unique allowing
comparison among different research areas.


title:
Extremely asymmetrical scattering in gratings with varying mean
  structural parameters

abstract:
  Extremely asymmetrical scattering (EAS) is an unusual type of Bragg
scattering in slanted periodic gratings with the scattered wave (the +1
diffracted order) propagating parallel to the grating boundaries. Here, a
unique and strong sensitivity of EAS to small stepwise variations of mean
structural parameters at the grating boundaries is predicted theoretically (by
means of approximate and rigorous analyses) for bulk TE electromagnetic waves
and slab optical modes of arbitrary polarization in holographic (for bulk
waves) and corrugation (for slab modes) gratings. The predicted effects are
explained using one of the main physical reasons for EAS--the diffractional
divergence of the scattered wave (similar to divergence of a laser beam). The
approximate method of analysis is based on this understanding of the role of
the divergence of the scattered wave, while the rigorous analysis uses the
enhanced T-matrix algorithm. The effect of small and large stepwise variations
of the mean permittivity at the grating boundaries is analysed. Two distinctly
different and unusual patterns of EAS are predicted in the cases of wide and
narrow (compared to a critical width) gratings. Comparison between the
approximate and rigorous theories is carried out.


title:
Analysis of on-line learning when a moving teacher goes around a true
  teacher

abstract:
  In the framework of on-line learning, a learning machine might move around a
teacher due to the differences in structures or output functions between the
teacher and the learning machine or due to noises. The generalization
performance of a new student supervised by a moving machine has been analyzed.
A model composed of a true teacher, a moving teacher and a student that are all
linear perceptrons with noises has been treated analytically using statistical
mechanics. It has been proven that the generalization errors of a student can
be smaller than that of a moving teacher, even if the student only uses
examples from the moving teacher.


title: TPC Performance in Magnetic Fields with GEM and Pad Readout

abstract:
  A novel charged particle tracking device, a high precision time projection
chamber with gas electron multiplier and pad readout, is a leading candidate as
the central tracker for an experiment at the International Linear Collider. To
characterize the performance of such a system, a small TPC has been operated
within a magnetic field, measuring cosmic-ray and laser tracks. Good tracking
resolution and two particle separation, sufficient for a large scale ILC
central tracker, are achieved.


title: Low crosstalk intersections of CCWs composed by mono-mode cavities

abstract:
  Low crosstalk intersections formed by two crossing coupled cavity waveguides
(CCWs), which are formed by series of \textit{mono-mode} cavities in a two
dimensional photonic crystal structure, are investigated. Although the
individual cavities are \textit{mono-mode}, the modes of the properly designed
CCWs (which are called \textit{supermodes} in this paper) may be dipole-like,
and antisymmetry along the axis of the other perpendicular CCW, which ensures
the low crosstalk of the intersections. According to the results of coupled
mode analysis, we divide the intersections into two kinds based on the number
of cavities of each CCW, and the transmission and crosstalk spectra of both
kinds are numerically obtained using finite difference time domain (FDTD)
method. The results show that crosstalk power is lower than -30dB. We also
discuss the factors that affect the performance of the intersections.


title:
Detailed analysis of the cell-inactivation mechanism by accelerated
  protons and light ions

abstract:
  Published survival data for V79 cells irradiated by monoenergetic protons,
helium-3, carbon, and oxygen ions and for CHO cells irradiated by carbon ions
have been analyzed using the probabilistic two-stage model of cell
inactivation. Three different classes of DNA damages formed by traversing
particles have been distinguished, namely severe single-track damages which
might lead to cell inactivation directly, less severe damages where cell
inactivation is caused by their combinations, and damages of negligible
severity that can be repaired easily. Probabilities of single ions to form
these damages have been assessed in dependence on their linear energy transfer
(LET) values.
  Damage induction probabilities increase with atomic number and LET. While
combined damages play crucial role at lower LET values, single-track damages
dominate in high-LET regions. The yields of single-track lethal damages for
protons have been compared with the Monte Carlo estimates of complex DNA
lesions, indicating that lethal events correlate well with complex DNA
double-strand breaks. The decrease in the single-track damage probability for
protons of LET above approx. 30 keV/$\mu$m, suggested by limited experimental
evidence, is discussed, together with the consequent differences in the
mechanisms of biological effects between protons and heavier ions. Applications
of the results in hadrontherapy treatment planning are outlined.


title:
Optical sorting and detection of sub-micron objects in a motional
  standing wave

abstract:
  An extended interference pattern close to surface may result in both a
transmissive or evanescent surface fields for large area manipulation of
trapped particles. The affinity of differing particle sizes to a moving
standing wave light pattern allows us to hold and deliver them in a
bi-directional manner and importantly demonstrate experimentally particle
sorting in the sub-micron region. This is performed without the need of fluid
flow (static sorting). Theoretical calculations experimentally confirm that
certain sizes of colloidal particles thermally hop more easily between
neighboring traps. A new generic method is also presented for particle position
detection in an extended periodic light pattern and applied to characterization
of optical traps and particle behavior


title:
Optimized interpolations and nonlinearity in numerical studies of
  woodwind instruments

abstract:
  We study the impedance spectra of woodwind instruments with arbitrary
axisymmetric geometry. We perform piecewise interpolations of the instruments'
profile, using interpolating functions amenable to analytic solutions of the
Webster equation. Our algorithm optimizes on the choice of such functions,
while ensuring compatibility of wavefronts at the joining points. Employing a
standard mathematical model of a single-reed mouthpiece as well as the
time-domain reflection function, which we derive from our impedance results, we
solve the Schumacher equation for the pressure evolution in time. We make
analytic checks that, despite the nonlinearity in the reed model and in the
evolution equation, solutions are unique and singularity-free.


title:
Coherent control with shaped femtosecond laser pulses applied to
  ultracold molecules

abstract:
  We report on coherent control of excitation processes of translationally
ultracold rubidium dimers in a magneto-optical trap by using shaped femtosecond
laser pulses. Evolution strategies are applied in a feedback loop in order to
optimize the photoexcitation of the Rb2 molecules, which subsequently undergo
ionization or fragmentation. A superior performance of the resulting pulses
compared to unshaped pulses of the same pulse energy is obtained by
distributing the energy among specific spectral components. The demonstration
of coherent control to ultracold ensembles opens a path to actively influence
fundamental photo-induced processes in molecular quantum gases.


title: Informational experiments with microparticles and atoms

abstract:
  Accepting information as a physical category and ascribing to inanimate
matter some spirit (consciousness, intelligence) allows to explain
quantum-mechanical phenomena, including delayed-choice and EPR-Bohm-Bell
experiments, as well as irreversibility of time, remaining on the basis of
local realism, and suggest essentially new experiments with microparticles and
atoms in which information plays the principal role.


title: Synthesis of scaling exponents: a fractional Levy model

abstract:
  Mandelbrot introduced the concept of fractals to describe the non-Euclidean
shape of many aspects of the natural world. In the time series context he
proposed the use of fractional Brownian motion (fBm) to model non-negligible
temporal persistence, the "Joseph Effect"; and Levy flights to quantify large
discontinuities, the "Noah Effect". In space physics, both effects are
manifested in the intermittency and long-range correlation which are by now
well-established features of geomagnetic indices and their solar wind drivers.
In order to capture and quantify the Noah and Joseph effects in one compact
model we propose the application of the "bridging" fractional Levy motion (fLm)
to space physics. We perform an initial evaluation of some previous scaling
results in this paradigm, and show how fLm can model the previously observed
exponents. We suggest some new directions for the future.


title: Long-range atom-surface interactions for cold atoms

abstract:
  Studies of the long-range interactions between cold atoms and surfaces are
now of vital interest. The interest is partly driven by nanotechnology
applications, partly by the exploding interest in the encompassing superfield
of Casimir effects, and partly by the burgeoning overlap between atomic and
molecular physics, condensed matter, and quantum optics. This tutorial lecture
will address long-range atom-surface interactions for cold atoms, including an
overview of Casimir-Polder interactions and their various manifestations. Some
previous theoretical studies that are of particular relevance will be reviewed.
In addition some different approaches to the problem and corresponding results,
especially concerning the effects of substrate composition, geometry, and
finite temperature, will be discussed.


title:
A combination of continuous-wave optical parametric oscillator and
  femtosecond frequency comb for optical frequency metrology

abstract:
  We combine a tunable continuous-wave optical parametric oscillator and a
femtosecond Ti:Sapphire laser frequency comb to provide a phase-coherent bridge
between the visible and mid-infrared spectral ranges. As a first demonstration
of this new technique we perform a direct frequency comparison between an
iodine stabilized Nd:YAG laser at 1064 nm and an infrared methane optical
frequency standard at $3.39 \mu$m.


title: Physics Based on Physical Monism

abstract:
  Based on a physical monism, which holds that the matter and space are
classified by not a difference of their kind but a difference of magnitude of
their density, I derive the most fundamental equation of motion, which is
capable of providing a deeper physical understanding than the known physics.
For example, this equation answers to the substantive reason of movement, and
Newton's second law, which has been regarded as the definition of force, is
derived in a substantive level from this equation. Further, the relativistic
energy-mass formula is generalized to include the potential energy term, and
the Lorentz force and Maxwell equations are newly derived.


title: Role of network connectivity in intercellular calcium oscillations

abstract:
  It is important to understand the coordinated performance of cells in tissue.
One possible mechanism in this coordination involves intracellular calcium
signaling. The topology of intercellular connections in tissue should also play
an important role in this process. It is most relevant for plane tissues, in
which the interaction between cells is due to gap junctions (epithelium, blood
vessels). We demonstrate the importance of the topology of intercellular
connectivity by investigating the properties of a model of calcium signaling
for a small number of connected cells.


title:
Signal processing by opto-optical interactions between self-localized
  and free propagating beams in liquid crystals

abstract:
  The reorientational nonlinearity of nematic liquid crystals enables a
self-localized spatial soliton and its waveguide to be deflected or destroyed
by a control beam propagating across the cell. We demonstrate a simple
all-optical readdressing scheme by exploiting the lens-like perturbation
induced by an external beam on both a nematicon and a co-polarized guided
signal of different wavelength. Angular steering as large as 2.2 degrees was
obtained for control powers as low as 32mW in the near infrared.


title: Is formal QED mathematically consistent?

abstract:
  The formal structure of quantum electrodynamics consists of various elements.
These include the Schroedinger equation which evolves the system forward in
time, the vacuum state which is assumed to be the state with a free field
energy of zero, and the principle of gauge invariance. In this paper we will
examine the mathematical consistency of these elements. It will be shown that
these elements, which are basic to the formal structure of the theory, are not
mathematically consistent.


title: A Spin Glass Model of Human Logic Systems

abstract:
  In this paper, we discuss different models for human logic systems and
describe a game with nature. Godel`s incompleteness theorem is taken into
account to construct a model of logical networks based on axioms obtained by
symmetry breaking. We start by saying that although an agent is rational, the
axioms defining different agent's logic systems need not be the same although
they might have a large degree of overlap. This can be seen as each agent being
coupled to a higher dimensional world by means of his perception where the
couplings produce slightly different projections of the higher dimensional
world to each agent. The different projections would produce slightly different
concepts about the "world" to each agent and hence create a slightly differing
set of axioms that each agent would use to act logically. Then we place the
agents in an interacting logical network, where these axioms can be treated as
spins that can be flipped as agents interact with each other and with the
environment in which they are placed. Agents, who would share a common material
world that they wish to use or change by using different or conflicting sets of
axioms will try to flip the other agent's axioms (This can be seen by observing
that as one agent acts to interact with his world as followed by his axiom,
another agent's world changes as well, and the change might be contradictory to
the second agent's "axioms" or "optimal world". We define an equation that
allows an axiom to be flipped into an "anti axiom (the opposite or conflicting
axiom)" as agents interact. All agents share an "existence" axiom by means of
which they strive to perpetuate themselves or the network.


title: High-resolution ab initio three-dimensional X-ray diffraction microscopy

abstract:
  Coherent X-ray diffraction microscopy is a method of imaging non-periodic
isolated objects at resolutions only limited, in principle, by the largest
scattering angles recorded. We demonstrate X-ray diffraction imaging with high
resolution in all three dimensions, as determined by a quantitative analysis of
the reconstructed volume images. These images are retrieved from the 3D
diffraction data using no a priori knowledge about the shape or composition of
the object, which has never before been demonstrated on a non-periodic object.
We also construct 2D images of thick objects with infinite depth of focus
(without loss of transverse spatial resolution). These methods can be used to
image biological and materials science samples at high resolution using X-ray
undulator radiation, and establishes the techniques to be used in
atomic-resolution ultrafast imaging at X-ray free-electron laser sources.


title:
Optimizing the Superlens: manipulating geometry to enhance the
  resolution

abstract:
  We analyze the performance of a planar lens based on realistic negative index
material in a generalized geometry. We demonstrate that the conventional
superlens design (where the lens is centered between the object and the image)
is not optimal from the resolution point-of-view, develop an analytical
expression for the resolution limit of a generalized lens, use it to find the
optimum lens configuration, and calculate the maximum absorption practical
nearfield superlenses may have. We demonstrate that in contrast to the
conventional superlens picture, planar imaging is typically accompanied by
excitation of surface waves at both interfaces of the lens.


title: Experimental Indications of Electro-Gravity

abstract:
  Recent results from our on going experimental investigation of the influence
of space dependant electric fields on the weight of test particles are
reported. Test particles were gold coated metal spheres of same size but of
different masses. Data collected from a number of runs over several years
continue to indicate an intriguing effect. For experimental parameters in
question this effect is manifested as a ppm level sample mass dependent force
additional to expected electrostatic forces. A force that is proportional to
mass is the unique signature of gravity furthermore it is non-zero only when
the field is applied; hence these observations may be further evidence in
support of electro-gravity.


title: On the inverse cascade of magnetic helicity

abstract:
  We study the inverse cascade of magnetic helicity in conducting fluids by
investigating the detailed transfer of helicity between different spherical
shells in Fourier space in direct numerical simulations of three-dimensional
magnetohydrodynamics (MHD). Two different numerical simulations are used, one
where the system is forced with an electromotive force in the induction
equation, and one in which the system is forced mechanically with an ABC flow
and the magnetic field is solely sustained by a dynamo action. The magnetic
helicity cascade at the initial stages of both simulations is observed to be
inverse and local (in scale space) in the large scales, and direct and local in
the small scales. When saturation is approached most of the helicity is
concentrated in the large scales and the cascade is non-local. Helicity is
transfered directly from the forced scales to the largest scales. At the same
time, a smaller in amplitude direct cascade is observed from the largest scale
to small scales.