title: Georeactor Variability and Integrity

abstract:
  As a deep-Earth energy source, the planetocentric nuclear-fission georeactor
concept is on a more secure scientific footing than the previous idea related
to the assumed growth of the inner core. Unlike previously considered
deep-Earth energy sources, which are essentially constant on a human
time-scale, variability in nuclear fission reactors can arise from changes in
composition and/or position of fuel, moderators, and neutron absorbers.
Tantalizing circumstantial evidence invites inquiry into the possibility of
short-term planetocentric nuclear fission reactor variability. This brief
communication emphasizes the importance of scientific integrity and highlights
the possibility of variable georeactor power output so that these might be
borne in mind in future investigations, especially those related to the Earth's
heat flux.


title:
Study of Large Hemispherical Photomultiplier Tubes for the ANTARES
  Neutrino Telescope

abstract:
  The ANTARES neutrino telescope, to be immersed depth in the Mediterranean
Sea, will consist of a 3 dimensional matrix of 900 large area photomultiplier
tubes housed in pressure resistant glass spheres. The selection of the optimal
photomultiplier was a critical step for the project and required an intensive
phase of tests and developments carried out in close collaboration with the
main manufacturers worldwide. This paper provides an overview of the tests
performed by the collaboration and describes in detail the features of the PMT
chosen for ANTARES.


title: Progress in Three-Dimensional Coherent X-Ray Diffraction Imaging

abstract:
  The Fourier inversion of phased coherent diffraction patterns offers images
without the resolution and depth-of-focus limitations of lens-based tomographic
systems. We report on our recent experimental images inverted using recent
developments in phase retrieval algorithms, and summarize efforts that led to
these accomplishments. These include ab-initio reconstruction of a
two-dimensional test pattern, infinite depth of focus image of a thick object,
and its high-resolution (~10 nm resolution) three-dimensional image.
Developments on the structural imaging of low density aerogel samples are
discussed.


title: Phase Aberrations in Diffraction Microscopy

abstract:
  In coherent X-ray diffraction microscopy the diffraction pattern generated by
a sample illuminated with coherent x-rays is recorded, and a computer algorithm
recovers the unmeasured phases to synthesize an image. By avoiding the use of a
lens the resolution is limited, in principle, only by the largest scattering
angles recorded. However, the imaging task is shifted from the experiment to
the computer, and the algorithm's ability to recover meaningful images in the
presence of noise and limited prior knowledge may produce aberrations in the
reconstructed image. We analyze the low order aberrations produced by our phase
retrieval algorithms. We present two methods to improve the accuracy and
stability of reconstructions.


title: 6D Muon Ionization Cooling with an Inverse Cyclotron

abstract:
  A large admittance sector cyclotron filled with LiH wedges surrounded by
helium or hydrogen gas is explored. Muons are cooled as they spiral
adiabatically into a central swarm. As momentum approaches zero, the momentum
spread also approaches zero. Long bunch trains coalesce. Energy loss is used to
inject the muons into the outer rim of the cyclotron. The density of material
in the cyclotron decreases adiabatically with radius. The sector cyclotron
magnetic fields are transformed into an azimuthally symmetric magnetic bottle
in the center. Helium gas is used to inhibit muonium formation by positive
muons. Deuterium gas is used to allow captured negative muons to escape via the
muon catalyzed fusion process. The presence of ionized gas in the center may
automatically neutralize space charge. When a bunch train has coalesced into a
central swarm, it is ejected axially with an electric kicker pulse.


title:
Spatial Random Field Models Inspired from Statistical Physics with
  Applications in the Geosciences

abstract:
  The spatial structure of fluctuations in spatially inhomogeneous processes
can be modeled in terms of Gibbs random fields. A local low energy estimator
(LLEE) is proposed for the interpolation (prediction) of such processes at
points where observations are not available. The LLEE approximates the spatial
dependence of the data and the unknown values at the estimation points by
low-lying excitations of a suitable energy functional. It is shown that the
LLEE is a linear, unbiased, non-exact estimator. In addition, an expression for
the uncertainty (standard deviation) of the estimate is derived.


title: E=mc^2, \Delta H = D(H-H)$, and the end of civilization

abstract:
  100 years ago Einstein discovered $E=mc^2$, the secret energy stored in
ordinary mass. $\Delta H = D(H-H)$ is the chemical energy released in chemical
bond formation between two H atoms. The failure to recognize the enormously
different energy scales in those two equations reflected in current events may
start a chain reaction this very year, on the one-hundredths anniversary of
Einstein's discovery, that leads to the end of civilization. Due to the
confluence of a particular set of circumstances, this particular moment is more
dangerous than any other in the history of nuclear weapons. Physicists have a
special responsibility to do their utmost to prevent this from happening. This
paper is a call to arms. A principle to underpin nuclear non-proliferation and
enhance stability is advocated.


title: Effect of Mass Fluctuation on Collective Modes in a Dusty Plasma

abstract:
  The grains immersed in plasma get eroded by the ions falling onto them. As a
consequence, they exhibit self-consistent mass fluctuations due to
perturbations in the plasma charging currents. The grain mass is then a
dynamical variable. The modifications in the plasma dielectric properties are
investigated and new ultra-low frequency modes are shown to exist in the
plasma.


title:
A common origin of the power law distributions in models of market and
  earthquake

abstract:
  We show that there is a common mode of origin for the power laws observed in
two different models: (i) the Pareto law for the distribution of money among
the agents with random saving propensities in an ideal gas-like market model
and (ii) the Gutenberg-Richter law for the distribution of overlaps in a
fractal-overlap model for earthquakes. We find that the power laws appear as
the asymptotic forms of ever-widening log-normal distributions for the agents'
money and the overlap magnitude respectively. The identification of the generic
origin of the power laws helps in better understanding and in developing
generalized views of phenomena in such diverse areas as economics and
geophysics.


title:
How soliton- anti soliton di quark pairs signify an Einstein constant
  dominated cosmology and facilitate reconstruction of initial dark matter
  contributions to CMB

abstract:
  We review the results of a model of how nucleation of a new universe occurs,
assuming a di quark identification for soliton-anti soliton constituent parts
of a scalar field. The intial potential system employed is semi classical in
nature, becoming non-classical at the end of chaotic inflation at the same time
cosmological expansion is dominated by the Einstein cosmological constant. We
use Scherrer's derivation of a sound speed being zero during initial
inflationary cosmology, and cange it afterwards as the slope of the scalar
field moves away from a thin wall approximation. All this is to aid in a data
reconstruction problem of how to account for the initial origins of CMB due to
dark matter since effective field theories as presently constructed require a
cut off value for applicability of their potential structure. This is often at
the cost of, especially in early universe theoretical models, of clearly
defined baryogenesis, and of a well defined mechanism of phase transitions. The
material below is now a proposal, in part accepted as a point of discussion as
a white paper (appropriately) submitted to the Dark Energy Task Force, in its
mission to advise (through its parent committees) the NSF, NASA and DOE. This
was for helping to select both ground-based and space-based techniques for
analyzing data as well as recommending the science requirements for a
space-based dark energy mission.


title:
Observation, modeling, and temperature dependence of doubly peaked
  electric fields in irradiated silicon pixel sensors

abstract:
  We show that doubly peaked electric fields are necessary to describe
grazing-angle charge collection measurements of irradiated silicon pixel
sensors. A model of irradiated silicon based upon two defect levels with
opposite charge states and the trapping of charge carriers can be tuned to
produce a good description of the measured charge collection profiles in the
fluence range from 0.5x10^{14} Neq/cm^2 to 5.9x10^{14} Neq/cm^2. The model
correctly predicts the variation in the profiles as the temperature is changed
from -10C to -25C. The measured charge collection profiles are inconsistent
with the linearly-varying electric fields predicted by the usual description
based upon a uniform effective doping density. This observation calls into
question the practice of using effective doping densities to characterize
irradiated silicon.


title:
Macroscopic Estimate of the Average Speed for New Particles Created in
  Collision

abstract:
  A {\it heuristic} approach is proposed to estimate the average speed of
particles during binary encounters by using the macroscopic variables with
their extended gradient-type which are the fundamental independent variables in
{\it extended thermodynamics} theory. We also address the missing contribution
(say, due to creation of new particles : {\it Acoustons}) in conventional
Bremsstrahlung.


title: Atmospheric hypotheses' of Earth's global warming

abstract:
  When analyzing the mean-year trend of the Earth's surface temperature for the
past 140 years one can discern two sections of monotone linear increase of
temperature during two last industrial centuries. The first one begins
somewhere in the period 1906-1909. The previous segment demonstrates a weak
decrease in the temperature trend, not increase. For explanation of this sudden
break we look for a phenomenon of cosmic scale during this time which could
have given rise to beginning of global warming with a significant probability.
On the 30th June 1908 Tungus meteorite exploded with the power of ~15 Mt TNT at
an altitude of ~10 km. Such an explosion could cause considerable stirring of
the high layers of atmosphere and change its structure in mesosphere. The
difference between this mesosphere catastrophe and atmospheric nuclear tests
that cause another break in the temperature plot is discussed. The purpose of
this report is to open the debate and to encourage discussion among scientists.


title:
Dynamics of the Markov Time Scale of Seismic Activity May Provide a
  Short-Term Alert for Earthquakes

abstract:
  We propose a novel method for analyzing precursory seismic data before an
earthquake that treats them as a Markov process and distinguishes the
background noise from real fluctuations due to an earthquake. A short time (on
the order of several hours) before an earthquake the Markov time scale $t_M$
increases sharply, hence providing an alarm for an impending earthquake. To
distinguish a false alarm from a reliable one, we compute a second quantity,
$T_1$, based on the concept of extended self-similarity of the data. $T_1$ also
changes strongly before an earthquake occurs. An alarm is accepted if {\it
both} $t_M$ and $T_1$ indicate it {\it simultaneously}. Calibrating the method
with the data for one region provides a tool for predicting an impending
earthquake within that region. Our analysis of the data for a large number of
earthquakes indicate an essentially zero rate of failure for the method.


title: Neutron physics in the early 1930s

abstract:
  Dawning neutron physics was more complex than one might expect. The chance
that the neutron comprised a proton and an electron was diffusely taken into
account after the discovery of the neutron. Moreover, uncertainties persisted
about the composition of beryllium radiation until it was realized that the
latter comprised both neutrons and gamma-rays. The interaction of neutrons with
matter and nuclei was soon investigated. Both a spatial symmetry, a symmetry of
charge, and a symmetry in the nuclear reactions soon emerged. The relation of
negative beta-decay to the neutron abundance in nuclei was moreover reviewed.
Positive beta-radioactivity induced by alpha-particles was eventually
announced, having been foreseen some weeks before. Accelerated deutons and
protons shortly afterwards revealed to be efficient in inducing radioactivity.
The physics institute in Rome got ready to start research on neutrons, but
apparently it only planned to go through alpha-induced radioactivity, at first.
If so, it is then plausible that some new results achieved by foreign
laboratories eventually bent Fermi to neutrons. Fermi's discovery of
neutron-induced radioactivity is reviewed with regard to investigations then
current, once more showing simplicity as a distinctive trait of Fermi's way of
doing physics.


title:
Contribution to the modeling of a liquid film flowing down inside a
  vertical circular tube

abstract:
  This note focuses on the development of a 2D model of a thin liquid film
flowing down inside a vertical pipe. This model is based on the large
wavelength assumption and valid for high Reynolds and Weber numbers.


title: Experiments with Compact Antenna Arrays for MIMO Radio Communications

abstract:
  The problem addressed in this study is how to design and test compact antenna
arrays for portable Mulitple-Input Multiple-Output (MIMO) transceivers. Mutual
coupling in an antenna array affects signal correlation and array radiation
efficiency - both of which have dramatic consequences for MIMO channel
capacity. Mutual coupling becomes more pronounced as array aperture shrinks and
is therefore a critical issue in compact array design. Two novel compact arrays
are designed and fabricated for use in MIMO enabled mobile devices. These
arrays are extremely compact yet demonstrate acceptable mutual coupling and
radiation efficiency because of the MIMO-specific criteria used during their
design. An experimental methodology is presented for fair and meaningful
characterization of MIMO arrays by field trial. This methodology addresses the
issue of capacity normalization and quantifies how well an antenna array's
radiation pattern interfaces with multipath propagation. Results are presented
from an extensive measurement campaign in which a true MIMO transceiver testbed
is outfitted with compact arrays and dipole arrays of various sizes. A
comprehensive and fair comparison is made between the compact arrays and dipole
arrays in a variety of indoor propagation scenarios. Design recommendations for
compact MIMO arrays are given.


title:
Time series of stock price and of two fractal overlap: Anticipating
  market crashes?

abstract:
  We find prominent similarities in the features of the time series for the
overlap of two Cantor sets when one set moves with uniform relative velocity
over the other and time series of stock prices. An anticipation method for some
of the crashes have been proposed here, based on these observations.


title:
Magnetic field-induced spectroscopy of forbidden optical transitions
  with application to lattice-based optical atomic clocks

abstract:
  We develop a method of spectroscopy that uses a weak static magnetic field to
enable direct optical excitation of forbidden electric-dipole transitions that
are otherwise prohibitively weak. The power of this scheme is demonstrated
using the important application of optical atomic clocks based on neutral atoms
confined to an optical lattice. The simple experimental implementation of this
method -- a single clock laser combined with a DC magnetic field-- relaxes
stringent requirements in current lattice-based clocks (e.g., magnetic field
shielding and light polarization), and could therefore expedite the realization
of the extraordinary performance level predicted for these clocks. We estimate
that a clock using alkaline earth-like atoms such as Yb could achieve a
fractional frequency uncertainty of well below 10^-17 for the metrologically
preferred even isotopes.


title: Mass Measurements and the Bound--Electron g Factor

abstract:
  The accurate determination of atomic masses and the high-precision
measurement of the bound-electron g factor are prerequisites for the
determination of the electron mass, which is one of the fundamental constants
of nature. In the 2002 CODATA adjustment [P. J. Mohr and B. N. Taylor, Rev.
Mod. Phys. 77, 1 (2005)], the values of the electron mass and the
electron-proton mass ratio are mainly based on g factor measurements in
combination with atomic mass measurements. In this paper, we briefly discuss
the prospects for obtaining other fundamental information from bound-electron g
factor measurements, we present some details of a recent investigation of
two-loop binding corrections to the g factor, and we also investigate the
radiative corrections in the limit of highly excited Rydberg S states with a
long lifetime, where the g factor might be explored using a double resonance
experiment.


title: Staging quantum cryptography with chocolate balls

abstract:
  Moderated by a director, laymen and students are encouraged to assume the
role of quanta and enact a quantum cryptographic protocol. The performance is
based on a generalized urn model capable of reproducing complementarity even
for classical chocolate balls.


title: Shot Noise Suppression in Avalanche Photodiodes

abstract:
  We identify a new shot noise suppression mechanism in a thin (~100 nm)
heterostructure avalanche photodiode. In the low-gain regime the shot noise is
suppressed due to temporal correlations within amplified current pulses. We
demonstrate in a Monte Carlo simulation that the effective excess noise factors
can be <1, and reconcile the apparent conflict between theory and experiments.
This shot noise suppression mechanism is independent of known mechanisms such
as Coulomb interaction, or reflection at heterojunction interfaces.


title:
The B61-based "Robust Nuclear Earth Penetrator:" Clever retrofit or
  headway towards fourth-generation nuclear weapons?

abstract:
  It is scientifically and technically possible to build an earth penetrating
device that could bury a B61-7 warhead 30 meters into concrete, or 150 meters
into earth, before detonating it. The device (based on knowledge and technology
that are available since 50 years) would however be large and cumbersome.
Better penetrator materials, components able to withstand larger stresses,
higher impact velocities, and/or high-explosive driven penetration aids, can
only marginally improve the device. It is concluded that the robust nuclear
earth penetrator (RNEP) program may be as much motivated by the development of
new technology directly applicable to next generation nuclear weapons, and by
the political necessity to periodically reassess the role and utility of
nuclear weapons, than by the perceived military need for a weapon able to
destroy deeply buried targets.


title:
Energy transfer in Hall-MHD turbulence: cascades, backscatter, and
  dynamo action

abstract:
  Scale interactions in Hall MHD are studied using both the mean field theory
derivation of transport coefficients, and direct numerical simulations in three
space dimensions. In the magnetically dominated regime, the eddy resistivity is
found to be negative definite, leading to large scale instabilities. A direct
cascade of the total energy is observed, although as the amplitude of the Hall
effect is increased, backscatter of magnetic energy to large scales is found, a
feature not present in MHD flows. The coupling between the magnetic and
velocity fields is different than in the MHD case, and backscatter of energy
from small scale magnetic fields to large scale flows is also observed. For the
magnetic helicity, a strong quenching of its transfer is found. We also discuss
non-helical magnetically forced Hall-MHD simulations where growth of a large
scale magnetic field is observed.


title:
Averaging methods for stochastic dynamics of complex reaction networks:
  description of multi-scale couplings

abstract:
  This paper is concerned with classes of models of stochastic reaction
dynamics with time-scales separation. We demonstrate that the existence of the
time-scale separation naturally leads to the application of the averaging
principle and elimination of degrees of freedom via the renormalization of
transition rates of slow reactions. The method suggested in this work is more
general than other approaches presented previously: it is not limited to a
particular type of stochastic processes and can be applied to different types
of processes describing fast dynamics, and also provides crossover to the case
when separation of time scales is not well pronounced. We derive a family of
exact fluctuation-dissipation relations which establish the connection between
effective rates and the statistics of the reaction events in fast reaction
channels. An illustration of the technique is provided. Examples show that
renormalized transition rates exhibit in general non-exponential relaxation
behavior with a broad range of possible scenarios.


title: A Precursor of Market Crashes

abstract:
  In this paper, we quantitatively investigate the properties of a statistical
ensemble of stock prices. We focus attention on the relative price defined as $
X(t) = S(t)/S(0) $, where $ S(0) $ is the initial price. We selected
approximately 3200 stocks traded on the Japanese Stock Exchange and formed a
statistical ensemble of daily relative prices for each trading day in the
3-year period from January 4, 1999 to December 28, 2001, corresponding to the
period in which the {\it internet Bubble} formed and {\it crashes} in the
Japanese stock market. We found that the upper tail of the complementary
cumulative distribution function of the ensemble of the relative prices in the
high value of the price is well described by a power-law distribution, $ P(S>x)
\sim x^{-\alpha} $, with an exponent that moves over time. Furthermore, we
found that as the power-law exponents $ \alpha $ approached {\it two}, the
bubble burst. It is reasonable to assume that when the power-law exponents
approached {\it two}, it indicates the bubble is about to burst.
  PACS: 89.65.Gh; Keywords: Market crashes, Power law, Precursor


title:
Corrections to the energy levels of a spin-zero particle bound in a
  strong field

abstract:
  Formulas for the corrections to the energy levels and wave functions of a
spin-zero particle bound in a strong field are derived. General case of the sum
of a Lorentz-scalar potential and zero component of a Lorentz-vector potential
is considered. The forms of the corrections differ essentially from those for
spin-1/2 particles. As an example of application of our results, we evaluated
the electric polarizability of a ground state of a spin-zero particle bound in
a strong Coulomb field.


title: MHD dynamo generation via Riemannian soliton theory

abstract:
  Heisenberg spin equation equivalence to nonlinear Schr\"{o}dinger equation
recently demonstrated by Rogers and Schief, is applied to the investigation of
vortex filaments in magnetohydrodynamics (MHD) dynamos. The use of
Gauss-Mainard-Codazzi equations allows us to investigate in detail the
influence of curvature and torsion of vortex filaments in the MHD dynamos. This
application follows closely previous applications to Heisenberg spin equation
to the investigations in magnetohydrostatics given by Schief (Plasma Physics
J.-2003).


title:
Scaling theory of temporal correlations and size dependent fluctuations
  in the traded value of stocks

abstract:
  Records of the traded value f_i(t) of stocks display fluctuation scaling, a
proportionality between the standard deviation sigma(i) and the average <f(i)>:
sigma(i) ~ f(i)^alpha, with a strong time scale dependence alpha(dt). The
non-trivial (i.e., neither 0.5 nor 1) value of alpha may have different origins
and provides information about the microscopic dynamics. We present a set of
recently discovered stylized facts, and then show their connection to such
behavior. The functional form alpha(dt) originates from two aspects of the
dynamics: Stocks of larger companies both tend to be traded in larger packages,
and also display stronger correlations of traded value.


title: Contact line motion for partially wetting fluids

abstract:
  We study the flow close to an advancing contact line in the limit of small
capillary number. To take into account wetting effects, both long and
short-ranged contributions to the disjoining pressure are taken into account.
In front of the contact line, there is a microscopic film corresponding to a
minimum of the interaction potential. We compute the parameters of the contact
line solution relevant to the matching to a macroscopic problem, for example a
spreading droplet. The result closely resembles previous results obtained with
a slip model.


title: The motion of the freely falling chain tip

abstract:
  The dynamics of the tip of the falling chain is analyzed. Results of
laboratory experiments are presented and compared with results of numerical
simulations. Time dependences of the velocity and the acceleration of the chain
tip for a number of different initial conformations of the chain are
determined. A simple analytical model of the system is also considered.


title: Migration induced epidemics: Dynamics of flux-based multipatch models

abstract:
  Classical disease models use a mass action term as the interaction between
infected and susceptible people in separate patches. We derive the equations
when this interaction is a migration of people between patches. The results
model what happens when a new population is moved into a region with endemic
disease.


title: Distribution of Return Intervals of Extreme Events

abstract:
  The distribution of return intervals of extreme events is studied in time
series characterized by finite-term correlations with non-exponential decay.
Precisely, it has been analyzed the statistics of the return intervals of
extreme values of the resistance fluctuations displayed by resistors with
granular structure in nonequilibrium stationary states. The resistance
fluctuations are calculated by Monte Carlo simulations using a resistor network
approach. It has been found that for highly disordered networks, when the
auto-correlation function displays a non-exponential and non-power-law decay,
the distribution of return intervals of the extreme values is a stretched
exponential, with exponent independent of the threshold.


title:
On the Distribution of State Values of Reproducing Cells: the General
  Evolution Equation and its Applications

abstract:
  Fluctuations of cell state, e.g., abundances of some proteins, have attracted
much attention both theoretically and experimentally. The distribution of such
state over cells, however, is not only a result of intracellular stochastic
process, but is also influenced by the growth in cell numbers that depends on
the state. By incorporating the growth-death process into the standard
Fokker--Planck equation for the probability distribution, a nonlinear temporal
evolution equation of distribution is obtained that includes a self-consistent
growth term. The derived equation is generally solved analytically by means of
eigenfunction expansions. By focusing on the case with linear relaxation, two
examples are considered as applications of the proposed general formalism.
First, by assuming that the growth rate of a cell increases linearly with the
state value $x$, the shift of the average state value $x$ due to the growth
effect is shown to be proportional to the variance of the state $x$ and the
relaxation time, similarly with the biological fluctuation- response
relationship. Second, when there is a gap in the growth rate at some threshold
value for the state $x$, existence of a critical gap value is demonstrated,
beyond which the average growth rate starts to increase. This critical value is
again obtained in terms of the relaxation time and the variance of $x$, all of
which are experimentally measurable quantities. The relevance of the results to
the analysis of biological data on the distribution of cell states, as obtained
for example by flow cytometry, is discussed.


title: A directed network model for World-Wide Web

abstract:
  In this paper, a directed network model for world-wide web is presented. The
out-degree of the added nodes are supposed to be scale-free and its mean value
is $m$. This model exhibits small-world effect, which means the corresponding
networks are of very short average distance and highly large clustering
coefficient. More interesting, the in-degree distribution obeys the power-law
form with the exponent $\gamma=2+1/m$, depending on the average out-degree.
This finding is supported by the empirical data, which has not been emphasized
by the previous studies on directed networks.


title: Dynamics of opinion formation in a small-world network

abstract:
  The dynamical process of opinion formation within a model using a local
majority opinion updating rule is studied numerically in networks with the
small-world geometrical property. The network is one in which shortcuts are
added to randomly chosen pairs of nodes in an underlying regular lattice. The
presence of a small number of shortcuts is found to shorten the time to reach a
consensus significantly. The effects of having shortcuts in a lattice of fixed
spatial dimension are shown to be analogous to that of increasing the spatial
dimension in regular lattices. The shortening of the consensus time is shown to
be related to the shortening of the mean shortest path as shortcuts are added.
Results can also be translated into that of the dynamics of a spin system in a
small-world network.


title: Asymptotic regime in N random interacting species

abstract:
  The asymptotic regime of a complex ecosystem with \emph{N}random interacting
species and in the presence of an external multiplicative noise is analyzed. We
find the role of the external noise on the long time probability distribution
of the i-th density species, the extinction of species and the local field
acting on the i-th population. We analyze in detail the transient dynamics of
this field and the cavity field, which is the field acting on the $i^{th}$
species when this is absent. We find that the presence or the absence of some
population give different asymptotic distributions of these fields.


title:
Talbot effect for dispersion in linear optical fibers and a wavelet
  approach

abstract:
  We shortly recall the mathematical and physical aspects of Talbot's
self-imaging effect occurring in near-field diffraction. In the rational
paraxial approximation, the Talbot images are formed at distances z=p/q, where
p and q are coprimes, and are superpositions of q equally spaced images of the
original binary transmission (Ronchi) grating. This interpretation offers the
possibility to express the Talbot effect through Gauss sums. Here, we pay
attention to the Talbot effect in the case of dispersion in optical fibers
presenting our considerations based on the close relationships of the
mathematical representations of diffraction and dispersion. Although dispersion
deals with continuous functions, such as gaussian and supergaussian pulses,
whereas in diffraction one frequently deals with discontinuous functions, the
mathematical correspondence enables one to characterize the Talbot effect in
the two cases with minor differences. In addition, we apply, for the first time
to our knowledge, the wavelet transform to the fractal Talbot effect in both
diffraction and fiber dispersion. In the first case, the self similar character
of the transverse paraxial field at irrational multiples of the Talbot distance
is confirmed, whereas in the second case it is shown that the field is not self
similar for supergaussian pulses. Finally, a high-precision measurement of
irrational distances employing the fractal index determined with the wavelet
transform is pointed out


title: The Donation-Payment Gift Card Concept: how to give twice with one card

abstract:
  Standard economic theory, starting with Adam Smith's invisible hand, holds
that those who trade for their own selfish motives of maximizing their private
preferences may contribute more to the public wealth than those who claim
altruistic motives. Under restrictive conditions, this has been shown to result
from a self-organizing mechanism acting at the global system level, which
ensures that optimal allocation of resources derives from competition within
the rule of law. In a nutshell, according to this view, being competitively
selfish adds value for all. But to what degree can doing good add competitive
value to products and services? We propose the creation of the Donation-Payment
card as a solution to the legal and moral issues plaguing the emerging
anonymous, direct-to-consumer, stored-value prepaid (SVP) card market. Our
proposal to redirect millions of dollars whose status is in conflict not only
improves society and empowers people, but also represents the best free-market
solution to the SVP-Cards industry. The Donation-Payment card kills two birds
with one stone by marrying business interests with societal benefits. In
addition, think of the state of mind of a grand-parent giving a SVP-card to a
grand-child, who also feels like "killing two birds with one stone" or should
we say more aptly feels like "giving twice with one card".


title: Circuit models for Sierpinski gasket antennas

abstract:
  A lumped-parameter impedor-oriented and a 2-port-network-oriented circuit
models for the Sierpinski gasket prefractal antenna are presented. With the
former, the voltage and current patterns give a detailed understanding of the
electromagnetic fields' self-similar distribution throughout the antenna
geometry; on the other hand model complexity exponentially increases with the
prefractal iteration order. The latter "black-box" model only controls
port-oriented global parameters which are the ones commonly used in antennas'
circuit models and its complexity is independent of prefractal order. The
"black-box" model is also shown to converge, at fractal limit, to a reciprocal
triangular network.


title: Gauge Invariance in Classical Electrodynamics

abstract:
  The concept of gauge invariance in classical electrodynamics assumes tacitly
that Maxwell's equations have unique solutions. By calculating the
electromagnetic field of a moving particle both in Lorenz and in Coulomb gauge
and directly from the field equations we obtain, however, contradicting
solutions. We conclude that the tacit assumption of uniqueness is not
justified. The reason for this failure is traced back to the inhomogeneous wave
equations which connect the propagating fields and their sources at the same
time.


title:
Fourth Generation Nuclear Weapons: Military effectiveness and collateral
  effects

abstract:
  The paper begins with a general introduction and update to Fourth Generation
Nuclear Weapons (FGNW), and then addresses some particularly important military
aspects on which there has been only limited public discussion so far. These
aspects concern the unique military characteristics of FGNWs which make them
radically different from both nuclear weapons based on previous-generation
nuclear-explosives and from conventional weapons based on chemical-explosives:
yields in the 1 to 100 tons range, greatly enhanced coupling to targets,
possibility to drive powerful shaped-charge jets and forged fragments, enhanced
prompt radiation effects, reduced collateral damage and residual radioactivity,
etc.


title:
Fine Structure Anomalies and Search for Variation of the Fine Structure
  Constant in Laboratory Experiments

abstract:
  Configuration interaction in many-electron atoms may cause anomalies in the
fine structure which make the intervals small and very sensitive to variation
of the fine structure constant. Repeated precision measurements of these
intervals over long period of time can put strong constrain on possible time
variation of the fine structure constant. We consider the $5p^4 \
^3$P$_{2,1,0}$ fine structure multiplet in the ground state of neutral
tellurium as an example. Here the effect of change of the fine structure
constant is enhanced about one hundred times in the relative change of the
small energy interval between the $^3$P$_1$ and $^3$P$_0$ states.


title:
The Explicit Simplified Interface Method for compressible multicomponent
  flows

abstract:
  This paper concerns the numerical approximation of the Euler equations for
multicomponent flows. A numerical method is proposed to reduce spurious
oscillations that classically occur around material interfaces. It is based on
the "Explicit Simplified Interface Method" (ESIM), previously developed in the
linear case of acoustics with stationary interfaces (2001, J. Comput. Phys.
168, pp.~227-248). This technique amounts to a higher order extension of the
"Ghost Fluid Method" introduced in Euler multicomponent flows (1999, J. Comput.
Phys. 152, pp. 457-492). The ESIM is coupled to sophisticated shock-capturing
schemes for time-marching, and to level-sets for tracking material interfaces.
Jump conditions satisfied by the exact solution and by its spatial derivative
are incorporated in numerical schemes, ensuring a subcell resolution of
material interfaces inside the meshing. Numerical experiments show the
efficiency of the method for rich-structured flows.


title:
Femtosecond spectral electric field reconstruction using coherent
  transients

abstract:
  We have implemented a new approach for measuring the time-dependent intensity
and phase of ultrashort optical pulses. It is based on the interaction between
shaped pulses and atoms, leading to coherent transients.


title: Incorporating Inertia Into Multi-Agent Systems

abstract:
  We consider a model that demonstrates the crucial role of inertia and
stickiness in multi-agent systems, based on the Minority Game (MG). The inertia
of an agent is introduced into the game model by allowing agents to apply
hypothesis testing when choosing their best strategies, thereby reducing their
reactivity towards changes in the environment. We find by extensive numerical
simulations that our game shows a remarkable improvement of global cooperation
throughout the whole phase space. In other words, the maladaptation behavior
due to over-reaction of agents is removed. These agents are also shown to be
advantageous over the standard ones, which are sometimes too sensitive to
attain a fair success rate. We also calculate analytically the minimum amount
of inertia needed to achieve the above improvement. Our calculation is
consistent with the numerical simulation results. Finally, we review some
related works in the field that show similar behaviors and compare them to our
work.


title:
Adiabatic radio frequency potentials for the coherent manipulation of
  matter waves

abstract:
  Adiabatic dressed state potentials are created when magnetic sub-states of
trapped atoms are coupled by a radio frequency field. We discuss their
theoretical foundations and point out fundamental advantages over potentials
purely based on static fields. The enhanced flexibility enables one to
implement numerous novel configurations, including double wells, Mach-Zehnder
and Sagnac interferometers which even allows for internal state-dependent atom
manipulation. These can be realized using simple and highly integrated wire
geometries on atom chips.


title: Blackouts, risk, and fat-tailed distributions

abstract:
  We analyze a 19-year time series of North American electric power
transmission system blackouts. Contrary to previously reported results we find
a fatter than exponential decay in the distribution of inter-occurrence times
and evidence of seasonal dependence in the number of events. Our findings
question the use of self-organized criticality, and in particular the sandpile
model, as a paradigm of blackout dynamics in power transmission systems.
Hopefully, though, they will provide guidelines to more accurate models for
evaluation of blackout risk.


title: New mechanism for EM waves? generation as a response to earthquakes

abstract:
  A mechanism that explains the increase of electromagnetic (EM) perturbations
during earthquakes is proposed. When earthquakes occur, surface waves propagate
along the globe surface inducing a globe surface rippling, which is reproduced
in an amplified manner at the atmosphere-ionosphere interface. A surface EM
wave that imparts a quiver velocity to electrons propagates along the rippled
interface encountering a periodic plasma density. A non-linear density current
is consequently generated that is a source of EM waves. The wave equation is
solved and the EM field is determined.


title: The Uehling correction to the energy levels in a pionic atom

abstract:
  We consider a correction to energy levels in a pionic atom induced by the
Uehling potential, i.e., by a free electron vacuum-polarization loop. The
calculation is performed for circular states (l=n-1). The result is obtained in
a closed analytic form as a function of $ Z\alpha$ and the pion-to-electron
mass ratio. Certain asymptotics of the result are also presented.


title: Student understanding of rotational and rolling motion concepts

abstract:
  We investigated the common difficulties that students have with concepts
related to rotational and rolling motion covered in the introductory physics
courses. We compared the performance of calculus- and algebra-based
introductory physics students with physics juniors who had learned rotational
and rolling motion concepts in an intermediate level mechanics course.
Interviews were conducted with six physics juniors and ten introductory
students using demonstration-based tasks. We also administered free-response
and multiple-choice questions to a large number of students enrolled in
introductory physics courses, and interviewed six additional introductory
students on the test questions (during the test design phase). All students
showed similar difficulties regardless of their background, and higher
mathematical sophistication did not seem to help acquire a deeper
understanding. We found that some difficulties were due to related difficulties
with linear motion, while others were tied specifically to the more intricate
nature of rotational and rolling motion.


title:
Comparing different models of aftershock rate decay: the role of catalog
  incompleteness in the first times after main shock

abstract:
  We evaluated the efficiency of various models in describing the time decay of
aftershock rate of 47 simple sequences occurred in California (37) from 1933 to
2004 and in Italy (10) from 1976 to 2004. We compared the models by the
corrected Akaike Information Criterion (AICc) and the Bayesian Information
Criterion (BIC), both based on the log-likelihood function but also including a
penalty term that takes into account the number of independent observations and
of free parameters of each model. We compared the performance of different
models by varying the starting time Ts and the minimum magnitude threshold Mmin
for each sequence. We found that Omori-type models including parameter c are
preferable to those not including it, only for short Ts and low Mmin while the
latters generally perform better than the formers for Ts longer than a few
hours and Mmin larger than the main shock magnitude Mm minus 3 units. This
clearly indicates that a value of parameter c different from zero does not
represent a general property of aftershock sequences in California and Italy
but it is very likely induced in most cases by catalog incompleteness in the
first times after the main shock. We also considered other models of aftershock
decay proposed in the literature: the Stretched Exponential Law in two forms
(including and not including a time shift) and the band Limited Power Law
(LPL). We found that such models perform worse than the Modified Omori Model
(MOM) and other Omori-type models for the large majority of sequences, although
for LPL, the relatively short duration of the analyzed sequences (one year)
might also contribute to its poor performance.


title:
Solution of the equations of electromagnetic self-consistency in a
  plasma

abstract:
  The system of equations of electromagnetic self-consistency in a plasma is
analytically solved for the case of a two-component homogeneous plasma in the
non-relativistic approximation.

categories: physics.plasm-ph math-ph math.MP physics.class-ph


title: QED Effects in Heavy Few-Electron Ions

abstract:
  Accurate calculations of the binding energies, the hyperfine splitting, the
bound-electron g-factor, and the parity nonconservation effects in heavy
few-electron ions are considered. The calculations include the relativistic,
quantum electrodynamic (QED), electron-correlation, and nuclear effects. The
theoretical results are compared with available experimental data. A special
attention is focused on tests of QED in a strong Coulomb field.


title:
Radiative and correlation effects on the parity-nonconserving transition
  amplitude in heavy alkaline atoms

abstract:
  The complete gauge-invariant set of the one-loop QED corrections to the
parity-nonconserving (PNC) amplitude in cesium and francium is evaluated to all
orders in $\alpha Z$ using a local form of the Dirac-Fock potential. The
calculations are performed in both length and velocity gauges for the absorbed
photon and the total binding QED correction is found to be $-$0.27(3)% for Cs
and $-$0.28(5)% for Fr. Moreover, a high-precision calculation of the
electron-correlation and Breit-interaction effects on the 7$s-8s$ PNC amplitude
in francium using a large-scale configuration-interaction Dirac-Fock method is
performed. The obtained results are employed to improve the theoretical
predictions for the PNC transition amplitude in Cs and Fr. Using an average
value from two most accurate measurements of the vector transition
polarizability, the weak charge of $^{133}$Cs is derived to amount to $
Q_W=-72.65(29)_{\rm exp}(36)_{\rm theor}$. This value deviates by $1.1\sigma$
from the prediction of the standard model. The values of the $7s$-$8s$ PNC
amplitude in $^{223}$Fr and $^{210}$Fr are obtained to be $-$15.49(15) and
$-$14.16(14), respectively, in units of i$\times 10^{-11}(-Q_W)/N$ a.u.


title:
Spatial Resolution of a Micromegas-TPC Using the Charge Dispersion
  Signal

abstract:
  The Time Projection Chamber (TPC) for the International Linear Collider will
need to measure about 200 track points with a resolution close to 100 $\mu$m. A
Micro Pattern Gas Detector (MPGD) readout TPC could achieve the desired
resolution with existing techniques using sub-millimeter width pads at the
expense of a large increase in the detector cost and complexity. We have
recently applied a new MPGD readout concept of charge dispersion to a prototype
GEM-TPC and demonstrated the feasibility of achieving good resolution with pads
similar in width to the ones used for the proportional wire TPC. The charge
dispersion studies were repeated with a Micromegas TPC amplification stage. We
present here our first results on the Micromegas-TPC resolution with charge
dispersion. The TPC resolution with the Micromegas readout is compared to our
earlier GEM results and to the resolution expected from electron statistics and
transverse diffusion in a gaseous TPC.


title: On the origin of the anomalous precession of Mercury's perihelion

abstract:
  Action at distance in Newtonian physics is replaced by finite propagation
speeds in classical post--Newtonian physics. As a result, the differential
equations of motion in Newtonian physics are replaced by functional
differential equations, where the delay associated with the finite propagation
speed is taken into account. Newtonian equations of motion, with
post--Newtonian corrections, are often used to approximate the functional
differential equations. In ``On the origin of quantum mechanics'', preprint,
physics/0505181, May 2005, a simple atomic model based on a functional
differential equation which reproduces the quantized Bohr atomic model was
presented. The unique assumption was that the electrodynamic interaction has a
finite propagation speed. In ``On the origin of the gravitational quantization:
The Titius--Bode Law'', preprint, physics/0507072, Jul 2005, a simple
gravitational model based on a functional differential equation which gives a
gravitational quantification and an explanation of the modified Titius--Bode
law is described. Firstly, in this work, we recall the calculations made by
Einstein to arrive at the explanation of the anomalous precession of Mercury's
perihelion. Secondly, we recover an ancient work of Gerber in 1898 as a
precursor of the retarded theories. In this paper Gerber gave an explanation of
the anomalous precession of the Mercury's perihelion in terms of a
velocity--dependent potential. In this paper an explanation of the anomalous
precession of Mercury's perihelion is given in terms of a simple retarded
potential, which, at first order, coincides with Gerber's potential, and which
agrees with the author's previous works.


title:
Proposed search for an electric-dipole moment using laser-cooled
  $^{171}$Yb atoms

abstract:
  We propose an experiment to search for a permanent atomic electric-dipole
moment (EDM) using laser-cooled $^{171}$Yb atoms launched in an atomic
fountain. A uniform B field sets the quantization axis, and the Ramsey
separated-oscillatory-fields method is used to measure the Zeeman precession
frequency of the atoms. Laser beams of appropriate polarization are used for
preparation and detection in a given magnetic sublevel. The signature of an EDM
is a shift in the Ramsey resonance correlated with application of a large E
field. The precision is expected to be at least 20 times better than current
limits because the use of a cold atomic beam allows application of E field 10
times larger than in a vapor cell, and the interaction time with the E field is
200 times larger compared to a thermal beam. The leading source of systematic
error in beam experiments, the (E x v/c) motional magnetic field, is reduced
considerably because of the near-perfect reversal of velocity between up and
down trajectories through the E-field region.


title: Doppler-free spectroscopy in driven three-level systems

abstract:
  We demonstrate two techniques for studying the features of three-level
systems driven by two lasers (called control and probe), when the transitions
are Doppler broadened as in room-temperature vapor. For $\Lambda$-type systems,
the probe laser is split to produce a counter-propagating pump beam that
saturates the transition for the zero-velocity atoms. Probe transmission then
shows Doppler-free peaks, which can even have sub-natural linewidth. For V-type
systems, the transmission of the control beam is detected as the probe laser is
scanned. The signal shows Doppler-free peaks when the probe laser is resonant
with transitions for the zero-velocity group. Both techniques greatly simplify
the study of three-level systems since theoretical predictions can be directly
compared without complications from Doppler broadening and the presence of
multiple hyperfine levels in the spectrum.


title:
Meandering rivulets on a plane: a simple balance between inertia and
  capillarity?

abstract:
  Experiments on streams of water flowing down a rigid substrate have been
performed for various plate inclinations and flow rates, and we focused on the
regime of stationary meanders. The outcome is that (i) the flow is highly
hysteretic : the shape of the meanders varies with flow rate only for
increasing flow rates, and the straight rivulet regime does not appear for
decreasing flow rate. (ii) A simple force balance, including inertia, capillary
forces, and also hysteresis of wetting, accounts well for the experimental
instability threshold flow rate and for the final radius of curvature of the
meanders.


title: Teaching Earth Dynamics: What's Wrong with Plate Tectonics Theory?

abstract:
  Textbooks frequently extol plate tectonics theory without questioning what
might be wrong with the theory or without discussing a competitive theory. How
can students be taught to challenge popular ideas when they are only presented
a one-sided view? In just a few pages, I describe more than a century of
geodynamic ideas. I review what is wrong with plate tectonics theory and with
Earth expansion theory, and describe my new Whole-Earth Decompression Dynamics
Theory, which unifies the two previous dominant theories in a self- consistent
manner. Along the way, I disclose details of what real science is all about,
details all too often absent in textbooks and classroom discussions. In these
few pages, I only touch on highlights and just part the curtain a bit so that
teachers might glimpse ways to bring to their students some of the richness and
excitement of discovery that becomes evident when one begins to question
prevailing, currently popular perceptions of our world.


title:
Equilibrium molecular energies used to obtain molecular dissociation
  energies and heats of formation within the bond-order correlation approach

abstract:
  Ab initio calculations including electron correlation are still extremely
costly except for the smallest atoms and molecules. Therefore, our purpose in
the present study is to employ a bond-order correlation approach to obtain, via
equilibrium molecular energies, molecular dissociation energies and heats of
formation for some 20 molecules containing C, H, and O atoms, with a maximum
number of electrons around 40. Finally, basis set choice is shown to be
important in the proposed procedure to include electron correlation effects in
determining thermodynamic properties. With the optimum choice of basis set, the
average percentage error for some 20 molecules is approximately 20% for heats
of formation. For molecular dissociation energies the average error is much
smaller: ~0.4.


title: Experimental investigation of optical atom traps with a frequency jump

abstract:
  We study the evolution of a trapped atomic cloud subject to a trapping
frequency jump for two cases: stationary and moving center of mass. In the
first case, the frequency jump initiates oscillations in the cloud's momentum
and size. At certain times we find the temperature is significantly reduced.
When the oscillation amplitude becomes large enough, local density increases
induced by the anharmonicity of the trapping potential are observed. In the
second case, the oscillations are coupled to the center of mass motion through
the anharmonicity of the potential. This induces oscillations with even larger
amplitudes, enhancing the temperature reduction effects and leading to
nonisotropic expansion rates while expanding freely.


title: DNA properties investigated by dynamic force microscopy

abstract:
  In this work, we show that by varying the experimental conditions, the
driving amplitude, a dynamic force microscope allows DNA properties to be
selectively imaged. The substrate on which the DNA is fixed is a silica surface
grafted with silanes molecules ended with amine groups. Use of small
oscillation amplitudes favors the attractive interaction between the tip and
the sample, while use of large amplitudes renders the contribution of the
attractive interaction negligible. Particularly, at small amplitudes, the
images show that the attractive interaction is strongly enhanced along the DNA.
This enhancement is found to be amenable with a model considering a narrow
strip of randomly oriented dipoles on each side of the molecule. This work
should provide new insights on the DNA interaction and conformational changes
with localized charges.


title:
Structural Characterization of Self-Assembled Monolayers of
  Organosilanes Chemically Bonded on Silica Wafers by Dynamical Force
  Microscopy

abstract:
  In this article, a dynamical force microscopy study of self-assembled
monolayers of organosilanes, grafted on a silica support, is reported.
Organosilanes, terminated either with a functional group (ethylene glycol) or
with a methyl group, were used. The influence of the reaction time and the
solvent composition on the grafting was investigated to improve the homogeneity
of the self-assembled monolayers. Numerical simulations of approach-retract
curves, obtained in the tapping mode, were performed and compared to
experimental ones. Informations, such as mechanical response and height of the
grafted organic layers, have been obtained.


title:
Stability criterions of an oscillating tip-cantilever system in dynamic
  force microscopy

abstract:
  This work is a theoretical investigation of the stability of the non-linear
behavior of an oscillating tip-cantilever system used in dynamic force
microscopy. Stability criterions are derived that may help to a better
understanding of the instabilities that may appear in the dynamic modes,
Tapping and NC-AFM, when the tip is close to a surface. A variational principle
allows to get the temporal dependance of the equations of motion of the
oscillator as a function of the non-linear coupling term. These equations are
the basis for the analysis of the stability. One find that the branch
associated to frequencies larger than the resonance is always stable whereas
the branch associated to frequencies smaller than the resonance exhibits two
stable domains and one unstable. This feature allows to re-interpret the
instabilities appearing in Tapping mode and may help to understand the reason
why the NC-AFM mode is stable.


title:
Stability of an oscillating tip in Non-Contact Atomic Force Microscopy:
  theoretical and numerical investigations

abstract:
  This paper is a theoretical and a numerical investigation of the stability of
a tip-cantilever system used in Non-Contact Atomic Force Microscopy (NC-AFM)
when it oscillates close to a surface. No additional dissipative force is
considered. The theoretical approach is based on a variationnal method
exploiting a coarse grained operation that gives the temporal dependence of the
nonlinear coupled equations of motion in amplitude and phase of the oscillator.
Stability criterions for the resonance peak are deduced and predict a stable
behavior of the oscillator in the vicinity of the resonance. The numerical
approach is based on results obtained with a virtual NC-AFM developped in our
group. The effect of the size of the stable domain in phase is investigated.
These results are in particularly good agreement with the theoretical
predictions. Also they show the influence of the phase shifter in the feedback
loop and the way it can affect the damping signal.


title:
Dissipation induced by attractive interaction in dynamic force
  microscopy : contribution of adsorbed water layers

abstract:
  At room temperature and under ambient conditions, due to the adsorption, a
water film is always present on silica surfaces. If the surface is investigated
with a scanning probe method in Contact mode, this causes the formation of a
meniscus between the tip and the surface. This liquid neck generates additional
capillary forces between the nano-tip and the surface. In dynamic mode, due to
the action of the oscillating tip on the surface, the mechanical response of
the adsorbed water layers can induce additional dissipation that is probed
through the phase variations of the oscillator. In the present work, we analyze
by dynamic force microscopy the growth of a water film on a silica surface as a
function of time. The silica sample is first cleaned and heated at
$420^\circ$C, then is exposed to dry conditions. The influence of the water
film is checked with the dynamic mode by using intermittent contact and
noncontact situations. To describe the experimental observations, additional
dissipation is taken into account when the tip approaches the surface. The
results of the fits allow the evaluation of the dissipation induced by the
attractive interaction between the tip and the silica surface related to the
adsorption of water molecules on surface as a function of time. Results are
compared to previous tribological studies performed in Contact mode and
infra-red spectroscopy measurements on the silica for which the key parameter
was the surface temperature instead of time. The two experimental results are
in good agreement.


title:
Influence of noncontact dissipation in the tapping mode: Attempt to
  extract quantitative information on the surface properties with the local
  force probe method

abstract:
  In the Tapping mode, a variation of the oscillation amplitude and phase as a
function of the tip sample distance is the necessary measurement to access
quantitatively to the properties of the surface. In the present work, we give a
systematic comparison between experimental data recorded on two surfaces, phase
and amplitude, and theoretical curves. With an interaction between the tip and
the surface taking into account an attractive and a repulsive term, the
analytical approach is unable to properly describe the relationship between the
phase variation and the oscillation amplitude variation. When an additional
dissipation term is involved, due to the attractive interaction between the tip
and the surface, the model gives a good agreement with the recorded data.
Particularly, the trends in the phase variations related to the noncontact
situations have been found to be amenable to an analysis based upon a simple
viscoelastic behavior of the surface.


title:
Nonlinear dynamical properties of an oscillating tip-cantilever system
  in the tapping mode

abstract:
  The dynamical properties of an oscillating tip-cantilever system are now
widely used in the field of scanning force microscopy. The aim of the present
work is to get analytical expressions describing the nonlinear dynamical
properties of the oscillator in noncontact and intermittent contact situations
in the tapping mode. Three situations are investigated: the pure attractive
interaction, the pure repulsive interaction, and a mixing of the two. The
analytical solutions obtained allow general trends to be extracted: the
noncontact and the intermittent contact show a very discriminate variation of
the phase. Therefore the measurement of the phase becomes a simple way to
identify whether or not the tip touches the surface during the oscillating
period. It is also found that the key parameter governing the structure of the
dynamical properties is the product of the quality factor by a reduced
stiffness. In the attractive regime, the reduced stiffness is the ratio of an
attractive effective stiffness and the cantilever one. In the repulsive regime,
the reduced stiffness is the ratio between the contact stiffness and the
cantilever one. The quality factor plays an important role. For large values of
the quality factor; it is predicted that a pure topography can be obtained
whatever the value of the contact stiffness. For a smaller quality factor, the
oscillator becomes more sensitive to change of the local mechanical properties.
As a direct consequence, varying the quality factor, for example with a vacuum
chamber, would be a very interesting way to investigate soft materials either
to access topographic information or nanomechanical properties.


title: Dry microfoams: Formation and flow in a confined channel

abstract:
  We present an experimental investigation of the agglomeration of microbubbles
into a 2D microfoam and its flow in a rectangular microchannel. Using a
flow-focusing method, we produce the foam in situ on a microfluidic chip for a
large range of liquid fractions, down to a few percent in liquid. We can
monitor the transition from separated bubbles to the desired microfoam, in
which bubbles are closely packed and separated by thin films. We find that
bubble formation frequency is limited by the liquid flow rate, whatever the gas
pressure. The formation frequency creates a modulation of the foam flow,
rapidly damped along the channel. The average foam flow rate depends
non-linearly on the applied gas pressure, displaying a threshold pressure due
to capillarity. Strong discontinuities in the flow rate appear when the number
of bubbles in the channel width changes, reflecting the discrete nature of the
foam topology. We also produce an ultra flat foam, reducing the channel height
from 250 $\mu$m to 8 $\mu$m, resulting in a height to diameter ration of 0.02;
we notice a marked change in bubble shape during the flow.


title:
A new determination of the fine structure constant based on Bloch
  oscillations of ultracold atoms in a vertical optical lattic

abstract:
  We report an accurate measurement of the recoil velocity of Rb atoms based on
Bloch oscillations in a vertical accelerated optical lattice. We transfer about
900 recoil momenta with an efficiency of 99.97 % per recoil. A set of 72
measurements of the recoil velocity, each one with a relative uncertainty of
about 33 ppb in 20 min integration time, leads to a determination of the fine
structure constant alpha with a statistical relative uncertainty of 4.4 ppb.
The detailed analysis of the different systematic errors yields to a relative
uncertainty of 6.7 ppb. The deduced value of 1/alpha is 137.03599878(91).


title: Message in the Sky

abstract:
  We argue that the cosmic microwave background (CMB) provides a stupendous
opportunity for the Creator of universe our (assuming one exists) to have sent
a message to its occupants, using known physics. Our work does not support the
Intelligent Design movement in any way whatsoever, but asks, and attempts to
answer, the entirely scientific question of what the medium and message might
be IF there was actually a message. The medium for the message is unique. We
elaborate on this observation, noting that it requires only careful adjustment
of the fundamental Lagrangian, but no direct intervention in the subsequent
evolution of the universe.


title: Enhanced parametric processes in binary metamaterials

abstract:
  We suggest double-resonant (binary) metamaterials composed of two types of
magnetic resonant elements, and demonstrate that in the nonlinear regime such
metamaterials provide unique possibilities for phase-matched parametric
interaction and enhanced second-harmonic generation.


title: The Hamilton-Jacobi Theory, Quantum Mechanics and General Relativity

abstract:
  The Hamilton-Jacobi theory of Classical Mechanics can be extended in a novel
manner to systems which are fuzzy in the sense that they can be represented by
wave functions. A constructive interference of the phases of the wave functions
then gives us back Classical systems. In a suitable description this includes
both Quantum Theory and General Relativity in the well known superspace
formulation. However, there are several nuances which provide insight into
these latter systems. All this is considered in this paper together with
suitable generalization, to cascades of super universes.


title:
A thermodynamic cycle more efficient than an infinite set of carnot
  engines operating between the same temperature levels

abstract:
  A theoretical thermodynamic cycle more efficient than an infinite set of
Carnot engines is presented. This result is unexpected from the point of view
of classical thermodynamics.


title: The stability of solitons in biomembranes and nerves

abstract:
  We examine the stability of a class of solitons, obtained from a
generalization of the Boussinesq equation, which have been proposed to be
relevant for pulse propagation in biomembranes and nerves. These solitons are
found to be stable with respect to small amplitude fluctuations. They emerge
naturally from non-solitonic initial excitations and are robust in the presence
of dissipation.


title: Optimal ranking in networks with community structure

abstract:
  The World-Wide Web (WWW) is characterized by a strong community structure in
which groups of webpages (e.g. those devoted to a common topic or belonging to
the same organization) are densely interconnected by hyperlinks. We study how
such network architecture affects the average Google rank of individual
communities. Using a mean-field approximation, we quantify how the average
Google rank of community webpages depends on the degree to which it is isolated
from the rest of the world in both incoming and outgoing directions, and
$\alpha$ -- the only intrinsic parameter of Google's PageRank algorithm. Based
on this expression we introduce a concept of a web-community being decoupled or
conversely coupled to the rest of the network. We proceed with empirical study
of several internal web-communities within two US universities. The predictions
of our mean-field treatment were qualitatively verified in those real-life
networks. Furthermore, the value $\alpha=0.15$ used by Google seems to be
optimized for the degree of isolation of communities as they exist in the
actual WWW.


title:
Theoretical and observed potential energy curves for neutral 4-unit
  charge Coulomb systems containing antihydrogen

abstract:
  Comparing observed and theoretical potential energy curves for natural and
exotic neutral 4-unit charge Coulomb systems like HH and HantiH leads to new
conclusions on the effect of charge-antisymmetry in nature. With singularities
in the HantiH PEC as found by Aldrovandi and Puget and by Junker and Bardsley,
any cusp in the HantiH PEC significantly affects the annihilation cross
section. This problem for the HantiH interaction generated many new wave
mechanical calculations mainly to remove annoying cusps. We review all
available PECs for 4-unit charge systems and find that corrections for the
Morgan-Hughes HantiH PEC can either go to the repulsive side (to the
conventionally expected annihilation channel) or to the opposite attractive
side (to the attractive branch of the observed PEC of natural molecular HH). We
observe that all theoretical HantiH PECs published thus far would intersect the
observed PEC of natural HH. This is, however, impossible with the non-crossing
rule. A classical ab initio calculation of the electrostatic perturbation
brings the HantiH PEC much closer to the observed HH PEC than to the PEC of the
annihilative channel. This new unprecedented result for long-range behavior in
4-unit charge Coulomb systems confirms that natural antiH must exist and that
molecule HH must be interpreted as HantiH. In fact, this seems to be the only
solution left, if PECs for systems HH and HantiH with the same symmetry cannot
cross.


title: Levy-Student Distributions for Halos in Accelerator Beams

abstract:
  We describe the transverse beam distribution in particle accelerators within
the controlled, stochastic dynamical scheme of the Stochastic Mechanics (SM)
which produces time reversal invariant diffusion processes. This leads to a
linearized theory summarized in a Shchr\"odinger--like (\Sl) equation. The
space charge effects have been introduced in a recent paper~\cite{prstab} by
coupling this \Sl equation with the Maxwell equations. We analyze the space
charge effects to understand how the dynamics produces the actual beam
distributions, and in particular we show how the stationary, self--consistent
solutions are related to the (external, and space--charge) potentials both when
we suppose that the external field is harmonic (\emph{constant focusing}), and
when we \emph{a priori} prescribe the shape of the stationary solution. We then
proceed to discuss a few new ideas~\cite{epac04} by introducing the generalized
Student distributions, namely non--Gaussian, L\'evy \emph{infinitely divisible}
(but not \emph{stable}) distributions. We will discuss this idea from two
different standpoints: (a) first by supposing that the stationary distribution
of our (Wiener powered) SM model is a Student distribution; (b) by supposing
that our model is based on a (non--Gaussian) L\'evy process whose increments
are Student distributed. We show that in the case (a) the longer tails of the
power decay of the Student laws, and in the case (b) the discontinuities of the
L\'evy--Student process can well account for the rare escape of particles from
the beam core, and hence for the formation of a halo in intense beams.

categories: physics.acc-ph cond-mat.stat-mech physics.plasm-ph quant-ph


title:
A phenomenological approach to the simulation of metabolism and
  proliferation dynamics of large tumour cell populations

abstract:
  A major goal of modern computational biology is to simulate the collective
behaviour of large cell populations starting from the intricate web of
molecular interactions occurring at the microscopic level. In this paper we
describe a simplified model of cell metabolism, growth and proliferation,
suitable for inclusion in a multicell simulator, now under development
(Chignola R and Milotti E 2004 Physica A 338 261-6). Nutrients regulate the
proliferation dynamics of tumor cells which adapt their behaviour to respond to
changes in the biochemical composition of the environment. This modeling of
nutrient metabolism and cell cycle at a mesoscopic scale level leads to a
continuous flow of information between the two disparate spatiotemporal scales
of molecular and cellular dynamics that can be simulated with modern computers
and tested experimentally.


title:
A Cosmic Archipelago: Multiverse Scenarios in the History of Modern
  Cosmology

abstract:
  Multiverse scenarios are common place in contemporary high energy physics and
cosmology, although many consider them simply as bold speculations. In any case
there is nothing like a single theory or a unified model of the multiverse.
Instead, there are innumerable theoretical proposals often reciprocally
incompatible. What is common to all these scenarios is the postulated existence
of many causally disjointed regions of space/time (if not completely separated
space-times) and the consideration of the observable universe as atypical in a
global perspective. This paper examines the history of modern cosmology
focusing on the forerunners of current ideas, and shows how some fundamental
issues tend to present themselves on increasingly deeper levels of physical
knowledge.


title: On statistical properties of traded volume in financial markets

abstract:
  In this article we study the dependence degree of the traded volume of the
Dow Jones 30 constituent equities by using a nonextensive generalised form of
the Kullback-Leibler information measure. Our results show a slow decay of the
dependence degree as a function of the lag. This feature is compatible with the
existence of non-linearities in this type time series. In addition, we
introduce a dynamical mechanism whose associated stationary probability density
function (PDF) presents a good agreement with the empirical results.


title:
Illustrating Einstein's special relativity: A relativistic diagram that
  displays in true values the components of a four vector

abstract:
  After having shown that the corresponding components of a four vector
transform via the same transformation factors as the space-time coordinates of
the same event do, we design a relativistic diagram that displays in true
values theirs components. One diagram works for events generated by tardyons
whereas a second diagram works for events generated by light signals or
photons. We consider both approaching and receding tardyons respectively
photons in each case. We also show how the relativistic diagram for radar and
photographic detections of moving profiles.


title: Taylor-Goldstein equation and stability

abstract:
  Taylor-Goldstein equation (TGE) governs the stability of a shear-flow of an
inviscid fluid of variable density. It is investigated here from a rigorous
geometrical point of view using a canonical class of its transformations.
Rayleigh's point of inflection criterion and Fjortoft's condition of
instability of a homogenous shear-flow have been generalized here so that only
the profile carrying the point of inflection is modified by the variation of
density. This fulfils a persistent expectation in the literature. A pair of
bounds exists such that in any unstable flow the flow-curvature (a function of
flow-layers) exceeds the upper bound at some flow-layer and falls below the
lower bound at a higher layer. This is the main result proved here. Bounds are
obtained on the growth rate and the wave numbers of unstable modes, in
fulfillment of longstanding predictions of Howard. A result of Drazin and
Howard on the boundedness of the wave numbers is generalized to TGE. The
results above hold if the local Richardson number does not exceed 1/4 anywhere
in the flow, otherwise a weakening of the conditions necessary for instability
is seen. Conditions for the propagation of neutrally stable waves and bounds on
the phase speeds of destabilizing waves are obtained. It is also shown that the
set of complex wave velocities of normal modes of an arbitrary flow is bounded.
Fundamental solutions of TGE are obtained and their smoothness is examined.
Finally sufficient conditions for instability are suggested.


title: Source-region calculation of dipole power

abstract:
  An exact calculation of the retarded electric field in the source region of a
system of individual charges, expanded to third order in velocity, shows that
all nonrelativistic accelerated charges in a system emit dipole electromagnetic
energy at the Larmor rate. In general, some of the emitted dipole power is
reabsorbed by doing work on other charges in the system, and some is radiated.
If the system has zero net dipole moment, all the emitted dipole power is
reabsorbed, and none is radiated.


title: B-identification for Level 2: The Silicon Track Trigger at D0

abstract:
  This article describes the Silicon Track Trigger (STT) which has been fully
commissioned in 2004 at the DO experiment. The STT allows to enrich already at
the second trigger level the data sample with events containing B-mesons. The
STT achieves this by providing within about 50 microseconds tracks with an
impact parameter resolution of around 50 micrometer. The article shows
preliminary results of the trigger performance and presents a fast
b-identification algorithm for the second trigger level.


title: Modeling bursts and heavy tails in human dynamics

abstract:
  Current models of human dynamics, used from risk assessment to
communications, assume that human actions are randomly distributed in time and
thus well approximated by Poisson processes. We provide direct evidence that
for five human activity patterns the timing of individual human actions follow
non-Poisson statistics, characterized by bursts of rapidly occurring events
separated by long periods of inactivity. We show that the bursty nature of
human behavior is a consequence of a decision based queuing process: when
individuals execute tasks based on some perceived priority, the timing of the
tasks will be heavy tailed, most tasks being rapidly executed, while a few
experiencing very long waiting times. We discuss two queueing models that
capture human activity. The first model assumes that there are no limitations
on the number of tasks an individual can hadle at any time, predicting that the
waiting time of the individual tasks follow a heavy tailed distribution with
exponent alpha=3/2. The second model imposes limitations on the queue length,
resulting in alpha=1. We provide empirical evidence supporting the relevance of
these two models to human activity patterns. Finally, we discuss possible
extension of the proposed queueing models and outline some future challenges in
exploring the statistical mechanisms of human dynamics.


title: Recognizing different types of stochastic processes

abstract:
  We propose a new cross-correlation method that can recognize independent
realizations of the same type of stochastic processes and can be used as a new
kind of pattern recognition tool in biometrics, sensing, forensic, security and
image processing applications. The method, which we call bispectrum correlation
coefficient method, makes use of the cross-correlation of the bispectra. Three
kinds of cross-correlation coefficients are introduced. To demonstrate the new
method, six different random telegraph signals are tested, where four of them
have the same power density spectrum. It is shown that the three coefficients
can map the different stochastic processes to specific sub-volumes in a cube.


title:
Growth kinetics of a nanoprotuberance under the action of an oscillating
  nanotip

abstract:
  The atomic force microscope is a versatile tool that allows many routes to be
used for investigating the mechanical properties of soft materials on the
nanometer scale. In the present work, experiments were performed on polystyrene
polymer films of various molecular weight by approaching a vibrating nanotip
towards the surface. The variation of the oscillating amplitude of the
cantilever is interpreted as the result of the growth process of a
nanoprotuberance. The growth rate is found to be dependent of the magnitude of
the oscillating amplitude and of the molecular weight. A model is developed
describing in a very simple way the action of the tip and a viscoelastic
response of the polymer. The numerical simulation helps in understanding the
nonlinear relation between the growth rate and the vibrating amplitude of the
microlever and describes qualitatively most of the experimental features. For
the softer material, experimental situations are found that allow the
experimental results to be amenable with an analytical solution. The analytical
solution provides a fruitful comparison with the experimental results showing
that some of the nanoprotuberance evolution cannot be explained with the
approximation used. The presents results show that there exists a new and
fascinating route to better understand the mechanical response at the local
scale.


title:
Nonlinear Dynamic Behavior of an Oscillating Tip-Microlever System and
  Contrast at the Atomic Scale

abstract:
  In this paper the dynamic behavior of an oscillating tip-microlever system at
the proximity of a surface is discussed. We show that the nonlinear behavior of
the oscillator is able to explain the high sensitivity of the oscillating tip
microlever and the observed shifts of the resonance frequency as a function of
the tip surface distance without the need of introducing a particular short
range force.


title:
Relationship between the non linear dynamic behaviour of an oscillating
  tip-microlever system and the contrast at the atomic scale

abstract:
  In this paper, the dynamic behaviour of an oscillating tip-microlever system
at the proximity of a surface is discussed. The attractive tip-surface
interaction is simply described with a Van der Waals dispersive term and a
sphere-plane geometry. We show that the non linear behaviour of the oscillator
is able to explain the observed shifts of the resonance frequency as a function
of the tip-surface distance without the need of introducing a particular short
range force.


title: An illustrative experiment on electromagnetic oscillations

abstract:
  It is the purpose of this manuscript to place an illustrative demonstration
on the measurement of damped electromagnetic oscillations for a RLC circuit
that it is easy to set in any physics laboratory equipped with PASCO
technologies and USB Electrical PASPort sensors together with standard
electrical components. The results of recording the electrical voltage with
DATA Studio software have a very good agreement with performed simulations from
MULTISIM software and/or standard calculations from theory. Our students and
instructors enjoy of the experiment for their simplicity set up in addition to
the instructive oscillations.


title: Lorentz Beams

abstract:
  A new kind of tridimensional scalar optical beams is introduced. These beams
are called Lorentz beams because the form of their transverse pattern in the
source plane is the product of two independent Lorentz functions. Closed-form
expression of free-space propagation under paraxial limit is derived and pseudo
non-diffracting features pointed out. Moreover, as the slowly varying part of
these fields fulfils the scalar paraxial wave equation, it follows that there
exist also Lorentz-Gauss beams, i.e. beams obtained by multipying the original
Lorentz beam to a Gaussian apodization function. Although the existence of
Lorentz-Gauss beams can be shown by using two different and independent ways
obtained recently from Kiselev [Opt. Spectr. 96, 4 (2004)] and Gutierrez-Vega
et al. [JOSA A 22, 289-298, (2005)], here we have followed a third different
approach, which makes use of Lie's group theory, and which possesses the merit
to put into evidence the symmetries present in paraxial Optics.


title:
On the scientific method learned from Albert Einstein in 2005 -- the
  World Year of Physics

abstract:
  We review the physics at the end of the nineteenth century and summarize the
process of the establishment of Special Relativity by Albert Einstein in brief.
Following in the giant's footsteps, we outline the scientific method which
helps to do research. We give some examples in illustration of this method. We
discuss the origin of quantum physics and string theory in its early years of
development. The discoveries of the neutrino and the correct model of solar
system are also present.


title:
Photonic Bloch oscillations and Zener tunneling in two-dimensional
  optical lattices

abstract:
  We report on the first experimental observation of photonic Bloch
oscillations and Zener tunneling in two-dimensional periodic systems. We study
the propagation of an optical beam in a square photonic lattice superimposed on
a refractive index ramp, and demonstrate the tunneling of light from the first
to the higher-order transmission bands of the lattice bandgap spectrum,
associated with the spectral dynamics inside the first Brillouin zone and
corresponding oscillations of the primary beam.


title: From heavy ions to exotic atoms

abstract:
  We review a number of experiments and theoretical calculations on heavy ions
and exotic atoms, which aim at providing informations on fundamental
interactions. Among those are propositions of experiments for parity violation
measurements in heavy ions and high-precision mesurements of He-like transition
energies in highly charged ions. We also describe recent experiments on pionic
atoms, that make use of highly-charged ion transitions to obtain accurate
measurements of strong interaction shift and width.


title:
Observational Derivation of Einstein's``Law of the Constancy of the
  Velocity of Light in Vacuo"

abstract:
  On the basis of Galilean invariance and the Doppler formula, combined with an
observational condition, it is shown that the constancy of the velocity of
light {\it in vacuo} can be derived, together with time-dilatation and Lorentz
contraction. It is not necessary to take the constancy as a postulate.


title: The Beginning of Chiral Symmetry

abstract:
  For readers interested in the history of chiral symmetry we present the
translation of two papaers from 1955 and 1959 from German to English, in which
chiral symmetry properties for weak and strong interactions have been
postulated and discussed.


title: Self-consistent resonance in a plasma

abstract:
  As an application of the solution of the equations of electromagnetic
self-consistency in a plasma, found in a previous paper, the study of
controlled thermo-nuclear fusion is undertaken. This study utilizes the
resonance which can be developed in the plasma, as indicated by the above
solution, and is based to an analysis of the underlying forced oscillation
under friction. As a consequence, we find that, in this way, controlled
thermonuclear fusion seems now to be feasible in principle. The treatment is
rather elementary, and it may serve as a guide for more detailed calculations.


title: A Method to check the Connectivity for the ATLAS TRT Detector

abstract:
  We report on a technique developed to diagnostic for non working readout
channels of the Transition Radiation Tracker (TRT), one of the three inner
detectors of the ATLAS experiment. From a detailled study, we show that 99.6 %
of the readout channels of the TRT endcap-detector are perfectly operational.


title: Nontrapping arrest of Langmuir wave damping near the threshold amplitude

abstract:
  Evolution of a Langmuir wave is studied numerically for finite amplitudes
slightly above the threshold which separates damping from nondamping cases.
Arrest of linear damping is found to be a second-order effect due to ballistic
evolution of perturbations, resonant power transfer between field and
particles, and organization of phase space into a positive slope for the
average distribution function $f_{av}$ around the resonant wave phase speed
$v_\phi$. Near the threshold trapping in the wave potential does not arrest
damping or saturate the subsequent growth phase.


title: Shaping soliton properties in optical Mathieu lattices

abstract:
  We address basic properties and stability of two-dimensional solitons in
photonic lattices induced by the nondiffracting Mathieu beams. Such lattices
allow for smooth topological transformation of radially symmetric Bessel
lattices into quasi-one-dimensional periodic ones. The transformation of
lattice topology drastically affects properties of ground-state and dipole-mode
solitons, including their shape, stability and transverse mobility.


title: Stability analysis of an oscillating tip-cantilever system in NC-AFM

abstract:
  This paper is a theoretical and a numerical investigation of the stability of
a tip-cantilever system used in noncontact atomic force microscopy (NC-AFM)
when it oscillates close to a surface. No additional dissipative force is
considered. The theoretical approach is based on a variational method
exploiting a coarse grained operation that gives the temporal dependance of the
non-linear coupled equations of motion in amplitude and phase of the
oscillator. Stability criterions for the resonance peak are deduced and predict
a stable behavior of the oscillator in the vicinity of the resonance. The
numerical approach is based on the results obtained with a virtual NC-AFM
developed by our group. The effect of the size of the stable domain in phase is
investigated. These results are in particularly good agreement with the
theoretical predictions. Also they show the influence of the phae shifter in
the feedback loop and the way it can affect the damping signal.


title:
Dipole-Field Contributions to Geometric-Phase-Induced False
  Electric-Dipole Moment Signals for Particles in Traps

abstract:
  It has been shown in an earlier publication that magnetic field gradients
applied to particles in traps can induce Larmor frequency shifts that may
falsely be interpreted as electric-dipole moment (EDM) signals. This study has
now been extended to include nonuniform magnetic field gradients due to the
presence of a local magnetic dipole. It is found that, in the high
orbit-frequency regime, the magnitude of the shifts can be enhanced beyond the
simple expectation of proportionality to the volume-averaged magnetic-field
gradient.


title:
High-resolution hyperfine spectroscopy of excited states using
  electromagnetically-induced transparency

abstract:
  We use the phenomenon of electromagnetically-induced transparency in a
three-level atomic system for hyperfine spectroscopy of upper states that are
not directly coupled to the ground state. The three levels form a ladder
system: the probe laser couples the ground state to the lower excited state,
while the control laser couples the two upper states. As the frequency of the
control laser is scanned, the probe absorption shows transparency peaks
whenever the control laser is resonant with a hyperfine level of the upper
state. As an illustration of the technique, we measure hyperfine structure in
the $7S_{1/2}$ states of $^{85}$Rb and $^{87}$Rb, and obtain an improvement of
more than an order of magnitude over previous values.


title:
Modelling gap-size distribution of parked cars using random-matrix
  theory

abstract:
  We apply the random-matrix theory to the car-parking problem. For this
purpose, we adopt a Coulomb gas model that associates the coordinates of the
gas particles with the eigenvalues of a random matrix. The nature of
interaction between the particles is consistent with the tendency of the
drivers to park their cars near to each other and in the same time keep a
distance sufficient for manoeuvring. We show that the recently measured
gap-size distribution of parked cars in a number of roads in central London is
well represented by the spacing distribution of a Gaussian unitary ensemble.


title: Instrumentation For Geological Fieldwork on the Moon

abstract:
  A human return to the Moon will require that astronauts are well equipped
with instrumentation to aid their investigations during geological field work.
Two instruments are described in detail. The first is a portable X-ray
Spectrometer, which can provide rapid geochemical analyses of rocks and soils,
identify lunar resources and aid selection of samples for return to Earth. The
second instrument is the Geological and Radiation environment package (GEORAD).
This is an instrument package, mounted on a rover, to perform in-situ
measurements on the lunar surface. It can be used for bulk geochemical
measurements of rocks and soils (particularly identifying KREEP-enriched
rocks), prospect for ice in shadowed areas of craters at the poles and
characterise the lunar radiation environment.


title: Transmission of Slow Light through Photonic Crystal Waveguide Bends

abstract:
  The spectral dependence of a bending loss of cascaded 60-degree bends in
photonic crystal (PhC) waveguides is explored in a slab-type
silicon-on-insulator system. Ultra-low bending loss of (0.05+/-0.03)dB/bend is
measured at wavelengths corresponding to the nearly dispersionless transmission
regime. In contrast, the PhC bend is found to become completely opaque for
wavelengths range corresponding to the slow light regime. A general strategy is
presented and experimentally verified to optimize the bend design for improved
slow light transmission.


title: Is a Plasma Diamagnetic?

abstract:
  Classical plasmas in thermodynamic equilibrium should be neither para- nor
diamagnetic due to the action of the Lorentz force. Magnetic confinement,
however, is based on the observed diamagnetism of laboratory plasmas. The
apparent paradox is investigated on the basis of the resistive
magneto-hydrodynamic equations. It is found that, at least in simple plasma
configurations, these equations do not permit a solution, i. e. the paradox
cannot be resolved. It seems that the Lorentz force is a test-particle
approximation which is not suitable to describe the interaction of moving
particles in agreement with the conservation of energy.


title: On the Solvability of Magnetic Differential Equations

abstract:
  The calculation of both resistive and ideal plasma equilibria amounts to
solving a number of magnetic differential equations which are of the type $\vec
{B}\cdot \nabla \Phi =s$. We apply the necessary and sufficient criterion for
the existence of the potential $\Phi$ and find that a static equilibrium
configuration of a magnetically confined plasma does not exist in axi-symmetric
toroidal geometry.


title: Compromise and Synchronization in Opinion Dynamics

abstract:
  We discuss two models of opinion dynamics. First wepresent a brief review of
the Hegselmann and Krause (HK) compromise model in two dimensions, showing that
it is possible to simulate the dynamics in the limit of an infinite number of
agents by solving numerically a rate equation for a continuum distribution of
opinions. Then, we discuss the Opinion Changing Rate (OCR) model, which allows
to study under which conditions a group of agents with a different natural
tendency (rate) to change opinion can find the agreement. In the context of the
this model, consensus is viewed as a synchronization process.


title: Universal Behavior of a Research Productivity Index

abstract:
  Indexes that account for good representations of an individual's productivity
are theme of major importance for the evaluation and comparison among
researchers. Recently, a new index was proposed combining productivity with
impact such that a researcher with index h has h papers with at least h
citations. A drawback of this is the sensitivity to the research field. Here we
propose a new index (hI) that accounts for the coauthorship effect. The
statistics of h and hI are presented for Brazilian research. We have found a
universal curve for different disciplines, allowing a comparison among
scientists of different research areas.


title: Vertex similarity in networks

abstract:
  We consider methods for quantifying the similarity of vertices in networks.
We propose a measure of similarity based on the concept that two vertices are
similar if their immediate neighbors in the network are themselves similar.
This leads to a self-consistent matrix formulation of similarity that can be
evaluated iteratively using only a knowledge of the adjacency matrix of the
network. We test our similarity measure on computer-generated networks for
which the expected results are known, and on a number of real-world networks.


title:
Sur un effet physique attribuable uniquement au potentiel vecteur en
  \'{e}lectromagn\'{e}tisme classique

abstract:
  We present the theory, the design and the discussion of an experiment which
allows to choose between the local formulation of Riemann-Lorenz and the
non-local formulation of Heaviside-Hertz in order to describe Classical
Electromagnetism.


title: A dry electrophysiology electrode using CNT arrays

abstract:
  We describe the concept of a dry electrode sensor for biopotential
measurement applications (ENOBIO) designed to eliminate the noise and
inconvenience associated to the use of electrolytic gel. ENOBIO uses
nanotechnology to remove gel-related noise, as well as maintaining a good
contact impedance to minimise interference noise. The contact surface of the
electrode will be covered with an array/forest of carbon nanotubes and will
also be tested with an Ag/AgCl coating to provide ionic-electronic
transduction. The nanotubes are to penetrate the outer layers of the skin, the
Stratum Corneum, improving electrical contact. We discuss requirements, skin
properties, nanotube penetration and transduction, noise sources, prototype
design logic and biocompatibility. A future paper will report test results.