title: Potential model of a 2D Bunsen flame

abstract:
  The Michelson Sivashinsky equation, which models the non linear dynamics of
premixed flames, has been recently extended to describe oblique flames. This
approach was extremely successful to describe the behavior on one side of the
flame, but some qualitative effects involving the interaction of both sides of
the front were left unexplained. We use here a potential flow model, first
introduced by Frankel, to study numerically this configuration. Furthermore,
this approach allows us to provide a physical explanation of the phenomena
occuring in this geometry by means of an electrostatic analogy.


title: Interfacing Friedman and string cosmologies

abstract:
  Compactification and symmetry breaking events in theories of heterotic
superstrings implicitly indicate five inflation events. Scales of 10^{9} ly and
larger are modeled in terms of these events. The proposed model accounts
qualitatively for recent observations (of galactic clusters that lie on
"thin,.. semi-spherical shells") and motivates a calculation that accounts
(approximately) for the observed number of galaxies.


title:
Combined phase space characterization at the PEP-II IP using single-beam
  and luminous-region measurements

abstract:
  We present a novel method to characterize the e+/- phase space at the IP of
the SLAC B-factory, that combines single-beam measurements with a detailed
mapping of luminous-region observables. Transverse spot sizes are determined in
the two rings with synchrotron-light monitors and extrapolated to the IP using
measured lattice functions. The specific luminosity, which is proportional to
the inverse product of the overlap IP beam sizes, is continuously monitored
using radiative-Bhabha events. The spatial variation of the luminosity and of
the transverse-boost distribution of the colliding e+/-, are measured using e+
e- --> mu+ mu- events reconstructed in the BaBar detector. The combination of
these measurements provide constraints on the emittances, horizontal and
vertical spot sizes, angular divergences and beta functions of both beams at
the IP during physics data-taking. Preliminary results of this combined
spot-size analysis are confronted with independent measurements of IP
beta-functions and overlap IP beam sizes at low beam current.


title:
First-order strong field approximation for high-order harmonic
  generation

abstract:
  Recently it was shown [A. Gordon and F. X. Kaertner, Phys. Rev. Lett. 95,
223901 (2005)] that the strong field approximation (SFA) for high-order
harmonic generation (HHG) is significantly improved when the SFA wave function
is used with the acceleration rather than the length form of the dipole
operator. In this work it is shown that using the acceleration form upgrades
the SFA from zeroth-order to first-order accuracy in the binding potential. The
first-order correct three-step model (1st-order TSM) obtained thereby is
systematically compared to its standard zeroth-order counterpart (0th-order
TSM) and it is found that they differ significantly even for energetic
electrons. For molecules (in the single-electron approximation), the 0th-order
and the 1st-order TSMs in general disagree about the connection between the
orbital symmetry and the positions of the minima in the HHG spectrum. At last,
we briefly comment on gauge and translation invariance issues of the SFA.


title: Can a single molecule trap the electron?

abstract:
  We suggest that it might be possible to trap the electron in a cavity of a
macrocycle molecule, in the same way this trapping occurs cooperatively, by
several solvent molecules, in hydroxylic liquids. Such an encapsulated electron
is a "molecular capacitor," in which the excess electron is largely decoupled
from valence electrons in the trap. A specific design for such a trap that is
based on calix[4]cyclohexanol is discussed in detail. It is shown
theoretically, by ab initio and density functional theory (DFT) modeling, that
one of the conformations of this molecule forms the optimum tetrahedral trap
for the electron. The resulting "encapsulated electron" strikingly resembles
the solvated electron in alcohols and water.


title:
General relativity and cosmology derived from principle of maximum power
  or force

abstract:
  The field equations of general relativity are shown to derive from the
existence of a limit force or of a limit power in nature. The limits have the
value of c^4/4G and c^5/4G. The proof makes use of a result by Jacobson. All
known experimental data is consistent with the limits. Applied to the universe,
the limits predict its darkness at night and the observed scale factor. Some
experimental tests of the limits are proposed. The main counter-arguments and
paradoxes are discussed, such as the transformation under boosts, the force
felt at a black hole horizon, the mountain problem, and the contrast to
scalar--tensor theories of gravitation. The resolution of the paradoxes also
clarifies why the maximum force and the maximum power have remained hidden for
so long. The derivation of the field equations shows that the maximum force or
power plays the same role for general relativity as the maximum speed plays for
special relativity.


title:
Study of x-ray emission enhancement via high contrast femtosecond laser
  interacting with solid foil

abstract:
  We studied the hard x-ray emission and the K-alpha x-ray conversion
efficiency produced by 60 fs high contrast frequency doubled Ti: sapphire laser
pulse focused on Cu foil target. Cu K-alpha photon emission obtained with
second harmonic laser pulse is more intense than the case of fundamental laser
pulse. The Cu K-alpha conversion efficiency shows strong dependence on laser
nonlinearly skewed pulse shape and reaches the maximum value 4x10-4 with 100 fs
negatively skewed pulse. It shows the electron spectrum shaping contribute to
the increase of conversion efficiency. Particle-in-cell simulations
demonstrates that the application of high contrast laser pulses will be an
effective method to optimize the x-ray emission, via the Enhanced Vacuum
Heating mechanism.


title: Woodpile and diamond structures by optical interference holography

abstract:
  We report the use of an optical interference holographic setup with a
five-beam configuration, consisting of four side beams and one central beam
from the same half space, to fabricate woodpile and diamond structures for the
use as photonic bandgap materials in which electromagnetic waves are forbidden
in the bandgap. By exploiting the advantage of the binarization of the
interference pattern, using intensity cut-off, either linear or circular
central beam can be used. More importantly, the beam configurations can be
easily implemented experimentally as compared to other configurations in which
the interfering beams are counter-propagating from both half spaces.


title:
A New Approach To The Evaluation Of The S-Matrix In Atom-Diatom Quantum
  Reactive Scattering Theory

abstract:
  A new approach is described to the evaluation of the S-matrix in
three-dimensional atom-diatom reactive quantum scattering theory. The theory is
developed based on natural collision coordinates where progress along the
reaction coordinate can be viewed as fulfilling the same role as time in a
time-dependent formulation. By writing the full wavefunction in coupled-channel
form it is proved that the 3D quantum reactive scattering problem can be
treated in the same way as an inelastic single-arrangement problem. In
particularly, two types of coupled-channel representations, which are reduced
to two different systems of coupled first order ordinary differential equations
describing the inelastic scattering, are used. The first system of coupled
differential equations is constructed on a set of points (grid) of the
coordinate reaction curve after solution of many 1D Schroedinger problems in
the directions normal to the reaction coordinate. The second expression for
inelastic scattering is found using exactly solvable nonstationary 1D
Schroedinger equation (etalon equation method), which is introduced for
describing the localization properties of the full wavefunction along the curve
of coordinate reaction. In this case we avoid a large amount of computation
involved in solving the 1D Schroedinger problem along the reaction coordinate
by using a slightly difficult initial conditions for the inelastic scattering
equations. In both cases by solving the system of coupled first order ordinary
differential equations, the full wavefunction and all S-matrix elements are
obtained simultaneously without further calculations. Our analysis shows that
the methods we have developed constitute the simplest algorithms for computing
the reactive scattering S-matrices.


title:
Quantum Mechanical Relations for the Energy, Momentum and Velocity of
  Single Photons in Dispersive Media

abstract:
  Attempts to explain the refraction of light in dispersive media in terms of a
photon or "corpuscular" model have heretofore been unable to account for the
observed decrease in the speed of light as it passes from air into a region of
higher refractive index n such as water or glass. In the present work it is
argued on the basis of the quantum mechanical relations p = k and E = h omega
that the energy of photons satisfies the equation E = pc/n. It is possible to
obtain an exact prediction of the observed speed of the photons in a given
medium by application of Hamilton's equations of motion to the above formula,
but at the same time to conclude, in agreement with the arguments of Newton and
other classical physicists, that the photon momentum increases in direct
proportion to n, thereby producing the well-known bending of light rays toward
the normal when entering water from air. The corresponding relativistic
particle theory of light indicates that the potential V encountered by the
photons in a given medium is attractive for n > 1 and is momentum-dependent,
which suggests the microscopic interactions responsible for the refraction of
light are non-Coulombic in nature and are instead akin to the spin-orbit and
orbit-orbit terms in the Breit-Pauli Hamiltonian for electrons moving in an
external field. The present theory concludes that the reason photons are slowed
down upon entering water from air is that their relativistic mass p/v increases
faster with n than does their momentum, which in turn requires that Einstein's
famous E = mc^2 formula does not hold for light dispersion because the energy
of the photons is expected to be the same in both media.


title: Language Time Series Analysis

abstract:
  We use the Detrended Fluctuation Analysis (DFA) and the Grassberger-Proccacia
analysis (GP) methods in order to study language characteristics. Despite that
we construct our signals using only word lengths or word frequencies, excluding
in this way huge amount of information from language, the application of
Grassberger- Proccacia (GP) analysis indicates that linguistic signals may be
considered as the manifestation of a complex system of high dimensionality,
different from random signals or systems of low dimensionality such as the
earth climate. The DFA method is additionally able to distinguish a natural
language signal from a computer code signal. This last result may be useful in
the field of cryptography.


title: Local microwave background radiation

abstract:
  An inquiry on a possible local origin for the Microwave Background Radiation
is made. Thermal MBR photons are contained in a system called {\it magnetic
bottle} which is due to Earth magnetic field and solar wind particles, mostly
electrons. Observational tests are anticipated.


title:
Turbulence characteristics of the B\"{o}dewadt layer in a large enclosed
  rotor-stator system

abstract:
  A three-dimensional (3D) direct numerical simulation is combined with a
laboratory study to describe the turbulent flow in an enclosed annular
rotor-stator cavity characterized by a large aspect ratio G=(b-a)/h=18.32 and a
small radius ratio a/b=0.152, where a and b are the inner and outer radii of
the rotating disk and h is the interdisk spacing. The rotation rate Omega under
consideration is equivalent to the rotational Reynolds number Re=Omegab2/nu=9.5
x 104, where nu is the kinematic viscosity of the fluid. This corresponds to a
value at which an experiment carried out at the laboratory has shown that the
stator boundary layer is turbulent, whereas the rotor boundary layer is still
laminar. Comparisons of the 3D computed solution with velocity measurements
have given good agreement for the mean and turbulent fields. The results
enhance evidence of weak turbulence at this Reynolds number, by comparing the
turbulence properties with available data in the literature. An approximately
self-similar boundary layer behavior is observed along the stator side. The
reduction of the structural parameter a1 under the typical value 0.15 and the
variation in the wall-normal direction of the different characteristic angles
show that this boundary layer is three-dimensional. A quadrant analysis of
conditionally averaged velocities is performed to identify the contributions of
different events (ejections and sweeps) on the Reynolds shear stress producing
vortical structures. The asymmetries observed in the conditionally averaged
quadrant analysis are dominated by Reynolds stress-producing events in this
B\"{o}dewadt layer. Moreover, case 1 vortices (with a positive wall induced
velocity) are found to be the major source of generation of special strong
events, in agreement with the conclusions of Lygren and Andersson.


title:
Cluster structure of EU-15 countries derived from the correlation matrix
  analysis of macroeconomic index fluctuations

abstract:
  The statistical distances between countries, calculated for various moving
average time windows, are mapped into the ultrametric subdominant space as in
classical Minimal Spanning Tree methods. The Moving Average Minimal Length Path
(MAMLP) algorithm allows a decoupling of fluctuations with respect to the mass
center of the system from the movement of the mass center itself. A Hamiltonian
representation given by a factor graph is used and plays the role of cost
function. The present analysis pertains to 11 macroeconomic (ME) indicators,
namely the GDP (x1), Final Consumption Expenditure (x2), Gross Capital
Formation (x3), Net Exports (x4), Consumer Price Index (y1), Rates of Interest
of the Central Banks (y2), Labour Force (z1), Unemployment (z2), GDP/hour
worked (z3), GDP/capita (w1) and Gini coefficient (w2). The target group of
countries is composed of 15 EU countries, data taken between 1995 and 2004. By
two different methods (the Bipartite Factor Graph Analysis and the Correlation
Matrix Eigensystem Analysis) it is found that the strongly correlated countries
with respect to the macroeconomic indicators fluctuations can be partitioned
into stable clusters.


title: Un manoscritto inedito in francese di Ettore Majorana

abstract:
  We report on the retrieval of the last missing papers of the "Senatore
folder", given by Majorana to one student of his in Naples in 1938, just before
his disappearance. The mentioned manuscript is conserved at the Domus
Galilaeana in Pisa (Italy), and was written in French, probably for a
conference in Leningrad (or in Kharkov) in 1933 (or in 1934). Majorana was
invited to attend to such a conference but, actually, he did not tke part to
it. The retrieved text deals with quantum electrodynamics by using the
formalism of field quantization. It is here reported, for the first time, in
translation. An accurate historical and scientific account is given as well.

categories: physics.hist-ph hep-ph hep-th physics.pop-ph


title: Resolution limit in community detection

abstract:
  Detecting community structure is fundamental to clarify the link between
structure and function in complex networks and is used for practical
applications in many disciplines. A successful method relies on the
optimization of a quantity called modularity [Newman and Girvan, Phys. Rev. E
69, 026113 (2004)], which is a quality index of a partition of a network into
communities. We find that modularity optimization may fail to identify modules
smaller than a scale which depends on the total number L of links of the
network and on the degree of interconnectedness of the modules, even in cases
where modules are unambiguously defined. The probability that a module conceals
well-defined substructures is the highest if the number of links internal to
the module is of the order of \sqrt{2L} or smaller. We discuss the practical
consequences of this result by analyzing partitions obtained through modularity
optimization in artificial and real networks.


title: Virtual volatility

abstract:
  We introduce the concept of virtual volatility. This simple but new measure
shows how to quantify the uncertainty in the forecast of the drift component of
a random walk. The virtual volatility also is a useful tool in understanding
the stochastic process for a given portfolio. In particular, and as an example,
we were able to identify mean reversion effect in our portfolio. Finally, we
briefly discuss the potential practical effect of the virtual volatility on an
investor asset allocation strategy.


title: Modified Newtonian dynamics as a prediction of general relativity

abstract:
  We consider a simple model of the physical vacuum as a self-gravitating
relativistic fluid. Proceeding in a step-by-step manner, we are able to show
that the equations of classical electrodynamics follow if the electromagnetic
four-potential is associated with the four-momentum of a space-filling fluid of
neutral spinors which we identify with neutrinos and antineutrinos. Charged
particles, which we identify with electrons and positrons, act as sinks for the
fluid and have the structure of the maximal fast Kerr solution. Electromagnetic
waves are described by oscillations in the fluid and interactions between
charges occur via the exchange of photons, which have the structure of entwined
neutrino-antineutrino pairs that form twisted closed loops in spacetime
connecting the charges. The model predicts that antimatter has negative mass,
and that neutrinos are matter-antimatter dipoles. Together these suffice to
explain the presence of modified Newtonian dynamics as a gravitational
polarisation effect.


title: Routines for the diagonalization of complex matrices

abstract:
  Jacobi-type iterative algorithms for the eigenvalue decomposition, singular
value decomposition, and Takagi factorization of complex matrices are
presented. They are implemented as compact Fortran 77 subroutines in a freely
available library.


title: On resolving the refractive index and the wave vector

abstract:
  The identification of the refractive index and wave vector for general
(possibly active) linear, isotropic, homogeneous, and non-spatially dispersive
media is discussed. Correct conditions for negative refraction necessarily
include the global properties of the permittivity and permeability functions
$\epsilon=\epsilon(\omega)$ and $\mu=\mu(\omega)$. On the other hand, a
necessary and sufficient condition for left-handedness can be identified at a
single frequency ($\re\epsilon/|\epsilon|+\re\mu/|\mu|<0$). At oblique
incidence to semi-infinite, active media it is explained that the wave vector
generally loses its usual interpretation for real frequencies.


title: Origin of the pearl necklace of SN1987A

abstract:
  The bright circles observed around stars are usually considered as produced
by shock waves; but this interpretation does not explain easily the bright
spots of the "pearl necklace" of NS 1987A supernova.
  Assuming that the central object of SN 1987A is a neutron star heated by the
accretion of a low density cloud, non-linear optics, in particular
superradiance and impulsive stimulated Raman scattering (ISRS), is needed to
take into account the high intensity of the radiated light.
  Where the temperature of the surrounding gas decreases enough to allow a
combination of protons and electrons into atomic hydrogen in despite of the low
density, a spherical shell absorbs in particular the Lyman alpha line, but does
not populate much the 2P state because a tangential superradiance appears until
the exciting line is almost absorbed; the increase of the 2P population
resulting from the disappearance of the superradiance produces a redshift, so
that almost all energy of a wide band is transferred to tangential modes making
an UV pearl necklace in a given direction of observation.
  In a column of UV light making a pearl, atomic lines are excited enough to
produce new, co-linear superradiances, in particular visible.


title:
Experimental Study of the Effect of External Signal on Microwave
  Oscillations in a Nonrelativistic Electron Beam with Virtual Cathode

abstract:
  The effect of an external harmonic signal on the characteristics of microwave
generation in a nonrelativistic electron beam with virtual cathode (VC) formed
in a static retarding electric field (low-voltage vircator system) has been
experimentally studied. A significant increase in the vircator generation power
is observed when the frequency of the external signal is close to the frequency
of VC oscillations. At large detunings, a broadband chaotic generation is
observed.


title: Delayed information flow effect in economy systems. An ACP model study

abstract:
  Applying any strategy requires some knowledge about the past state of the
system. Unfortunately in the case of economy collecting information is a
difficult, expensive and time consuming process. Therefore the information
about the system is known at the end of some well defined intervals, e. g.
company reports, inflation data, GDP etc. They describe a (market) situation in
the past. The time delay is specific to the market branch. It can be very short
(e.g. stock market offer is updated every minute or so and this information is
immediately available) or long, like months in the case of agricultural market,
when the decisions are taken based on the results from the previous harvest.
  The analysis of the information flow delay can be based on the ACP model of
spatial evolution of economic systems. The entities can move on a square
lattice and when meeting take one of the two following decisions: merge or
create a new entity. The decision is based on the system state, which is known
with some time delay. The effect of system's feedback is investigated. We
consider the case of company distribution evolution in a heterogenous field.
The information flow time delay implies different final states, including
cycles.


title: Vortex sheet dynamics and turbulence

abstract:
  The nonlinear evolution of a vortex sheet driven by the Kelvin--Helmholtz
instability is characterized by the formation of a spiral possessing complex
stretching and intensity patterns. We show that the power energy spectrum of a
single two-dimensional vortex sheet tends to the usual fluid turbulent
spectrum, with an exponent of -3. Using numerical simulations and asymptotic
methods, we demonstrate the relation between this power law and the
singularities in the geometry and vorticity distribution of the sheet.


title: Theory of aces: high score by skill or luck?

abstract:
  We studied the distribution of World War I fighter pilots by the number of
victories they were credited with, along with casualty reports. Using the
maximum entropy method we obtained the underlying distribution of pilots by
their skill. We find that the variance of this skill distribution is not very
large, and that the top aces achieved their victory scores mostly by luck. For
example, the ace of aces, Manfred von Richthofen, most likely had a skill in
the top quarter of the active WWI German fighter pilots and was no more special
than that. When combined with our recent study (cond-mat/0310049), showing that
fame grows exponentially with victory scores, these results (derived from real
data) show that both outstanding achievement records and resulting fame are
mostly due to chance.


title:
Quantum trajectory perspective of atom-field interaction in attosecond
  time scale

abstract:
  Here the ionization and high harmonic generation in Hydrogen and Helium by
using quantum (hydrodynamic) trajectories is analyzed theoretically. The
quantum trajectories allow a self-contained treatment of the electron exchange
and correlation effects without introducing ad hoc potentials into the
Schrodinger equation. Our approach predicts the correct high harmonic spectra
and the attosecond pulses generated by the Helium atom beyond the single active
electron approximation. It can be used to study complex multi-electron systems
and their interaction with laser field of both high and low intensity.


title:
Twelve shear surface waves guided by clamped/free boundaries in
  magneto-electro-elastic materials

abstract:
  It is shown that surface waves with twelve different velocities in the cases
of different magneto-electrical boundary conditions can be guided by the
interface of two identical magneto-electro-elastic half-spaces. The plane
boundary of one of the half-spaces is clamped while the plane boundary of the
other one is free of stresses. The 12 velocities of propagation of these
surface waves are obtained is explicit forms. It is shown that the number of
different surface wave velocities decreases from 12 to 2 if the
magneto-electro-elastic material is changed to a piezoelectric material.


title:
New pure shear elastic surface waves in magneto-electro-elastic
  half-space

abstract:
  Pure shear surface waves guided by the free surface of a
magneto-electro-elastic material are investigated. Three surface waves are
obtained for various magneto-electrical conditions on the free surface of the
magneto-electro-elastic half-space. The velocities of propagation and the
existence conditions for each of these waves are obtained in explicit exact
form.


title:
Eleven shear surface waves guided by inclusions in
  magneto-electro-elastic materials

abstract:
  Eleven pure shear surface waves are shown to exist in magneto-electro-elastic
materials, which contain different plane inclusions inside them. The plane
inclusions affect the electric and magnetic fields only, so that the medium
remains mechanically continuous across it. Expressions for velocities of
propagation of these 11 surface waves are obtained in explicit forms. It is
expected that these waves will have several applications in surface acoustic
wave devices.


title:
New pure shear acoustic surface waves guided by cuts in
  magneto-electro-elastic materials

abstract:
  It is shown that new pure shear acoustic surface waves with five different
velocities can be guided by stress free plane cuts with different
magneto-electrical properties in magneto-electro-elastic materials. The
possibility for the surface waves to be guided by a cut in pairs, which is
reported in this paper, is new in magneto-electro-elastic materials and has no
counterpart in piezoelectric materials. The five velocities of propagation of
the surface waves are obtained in explicit forms. It is shown that the
possibility for the surface waves to be guided in pairs disappears and the
number of surface waves decreases from 5 to 1 if the magneto-electro-elastic
material is changed to a piezoelectric material.


title: Solitary Waves in Dusty Plasmas with Nonthermal Ions

abstract:
  An investigation of dust-acoustic solitary waves in unmagnetized dusty plasma
whose constituents are inertial charged dust grains, Boltzmannian electrons and
nonthermal ions has been conducted. The pseudo potential as well as the
reductive perturbation methods have been used in high and small amplitude
limits. The existence of solitary waves of a positive as well as a negative
potential is reported.


title:
Utilisation de la substitution sensorielle par \'{e}lectro-stimulation
  linguale pour la pr\'{e}vention des escarres chez les parapl\'{e}giques.
  Etude pr\'{e}liminaire

abstract:
  Pressure ulcers are recognized as a major health issue in individuals with
spinal cord injuries and new approaches to prevent this pathology are
necessary. An innovative health strategy is being developed through the use of
computer and sensory substitution via the tongue in order to compensate for the
sensory loss in the buttock area for individuals with paraplegia. This sensory
compensation will enable individuals with spinal cord injuries to be aware of a
localized excess of pressure at the skin/seat interface and, consequently, will
enable them to prevent the formation of pressure ulcers by relieving the
cutaneous area of suffering. This work reports an initial evaluation of this
approach and the feasibility of creating an adapted behavior, with a change in
pressure as a response to electro-stimulated information on the tongue.
Obtained during a clinical study in 10 healthy seated subjects, the first
results are encouraging, with 92% success in 100 performed tests. These
results, which have to be completed and validated in the paraplegic population,
may lead to a new approach to education in health to prevent the formation of
pressure ulcers within this population. Keywords: Spinal Cord Injuries,
Pressure Ulcer, Sensory Substitution, Health Education, Biomedical Informatics.


title: The Stoner-Wohlfarth model of Ferromagnetism: Static properties

abstract:
  Recent advances in high-density magnetic storage and spin electronics are
based on the use of magnetic materials along with conventional microelectronic
materials (metals, insulators and semiconductors). The unit information (bit)
is stored as a magnetization state in some ferromagnetic ma rial (FM) and
controlled with an external field altering the magnetization state. As device
size is shrinking steadily toward the nanometer and the need to incr se its
bandwidth prevails, racing toward higher frequencies is getting even more cha
enging. In magnetic systems, denser storage leads to finer magnetic grains and
small size leads to single magnetic domain physics. The Stoner-Wohlfarth model
is the simplest model that describes adequately the physics of fine magnetic
grains containing single domains and where magnetization state changes by
rotation or switching (abrupt reversal). The SW model is reviewed and discussed
with its consequences and potential app cations in the physics of magnetism and
spin electronics.


title:
The Stoner-Wohlfarth model of Ferromagnetism: Dynamic and Statistical
  properties

abstract:
  The physics of magnetic state change or reversal in single domain magnetic
grains (called Stoner particles) is interesting from the fundamental as well as
the applied points of view. A change in magnetization can be finely tuned with
a specific time variation o f an externally applied magnetic field. It may also
occur naturally (without application of a field) at very low tempe rature with
quantum tunneling and at higher temperature with thermal excitation. The
optimal (usually shortest) time altering the magn etisation along with the
smallest applied magnetic field are sought in technological applications s uch
as high-density reading or writing of information, spintronics, quantum inform
ation and quantum communication systems. This work reviews the magnetization
change with a time dependent field and tem perature and discusses the time it
takes to alter the magnetization as a function of the control parameter chosen,
temperature and material parameters.


title: Magnetic domain-walls and the relaxation method

abstract:
  The relaxation method used to solve boundary value problems is applied to
study the variation of the magnetization orientation in several types of domain
walls that occur in ferromagnetic materials. The algorithm is explained and
applied to several cases: the Bloch wall in bulk magnetic systems, the radial
wall in cylindrical wires and the N\'eel wall in thin films


title:
Suppression of reflection from the grid boundary in solving the
  time-dependent Schroedinger equation by split-step technique with fast
  Fourier transform

abstract:
  We present an approach to numerically solving the time-dependent Schroedinger
equation and other parabolic equations by the split-step technique with fast
Fourier transform, which suppresses the backreflection of waves from the grid
boundaries with any specified accuracy. Most importantly, all known methods
work well only for a narrow region of incident waves spectrum, and the proposed
method provides absorption of any wave whose length is large enough in
comparison with the size of absorption region.


title:
Near-field imaging in the megahertz range by strongly coupled
  magnetoinductive surfaces: theoretical model and experimental validation

abstract:
  In this work, near-field imaging by two strongly coupled arrays of split ring
resonators is analyzed. A simple theoretical model is developed to obtain the
transfer function of the lens. This model shows that magnetoinductive surface
waves (MISWs) play the same role as plasmon-polaritons in negative refractive
slabs. In particular, the model predicts that the image is formed near the
resonant frequency of the rings, between the pass-bands for the two MISW
branches that can be excited in the lens. It also predicts a significant image
enhancement when the distance between the source source and the image plane is
smaller than twice the lens width. The predictions of the theoretical model are
supported by measurements in the radio-frequency range. This suggests the
possibility of using this kind of devices to imaging processes in the megahertz
range, as for example in magnetic resonance imaging.


title: String Scale Cosmological Constant

abstract:
  The cosmological constant is an unexplained until now phenomena of nature
that requires an explanation through string effects. The apparent discrepancy
between theory and experiment is enourmous and has already been explained
several times by the author including mechanisms. In this work the string
theory theory of abolished string modes is documented and given perturbatively
to all loop orders. The holographic underpinning is also exposed. The matching
with the data of the LIGO and D0 experiments is also explained to the first
three or more moments in the cosmological expansion.


title:
Metastable States in Two-Lane Traffic Flow Models With Slow-To-Start
  Rule

abstract:
  Using computer simulations, we show that metastable states still occur in
two-lane traffic models with slow to start rules. However, these metastable
states no longer exist in systems where aggressive drivers (\textit{which do
not look back before changing lanes}) are present. Indeed, the presence of only
one aggressive driver in the circuit, triggers the breakdown of the high flow
states. In these systems, the steady state is unique and its relaxation
dynamics should depend on the lane changing probability $p_{ch}$ and the number
of aggressive drivers present in the circuit. It is found also that the
relaxation time $\tau$ diverges as the form of a power-law : $\tau\propto
p_{ch}^{-\beta}, \beta=1$.


title:
Controllable vs uncontrollable nonlocality: Is it possible to achieve
  superluminal communication?

abstract:
  For over 7 decades it has been debated as to whether nonlocality is strictly
of an uncontrollable nature. Based upon polarization measurements with
entangled photons, it has been revealed that nonlocality cannot be used to
achieve controllable superluminal communication. A simple series of experiments
is proposed which may reveal that a rudimentary form of controllable
superluminal communication is possible, using human neural stem cells mounted
on microelectrode arrays, subject to laser stimulation at varying Hz levels.


title:
Evanescent wave interference and the total transparency of a warm
  high-density plasma slab

abstract:
  It is shown that an overcritical density plasma slab can be totally
transparent to a \textit{p}-polarized obliquely incident electromagnetic wave.
High transparency is achieved due to the interference of the evanescent waves
in the subcritical region. The transmission coefficient has the resonant
character due to the excitation of a plasma surface mode (plasmon-polariton).
It is crucial that two evanescent waves have certain phase shift to provide
non-zero energy flux through non-transparent region. The required phase shift
is obtained at the exact resonance and corresponds to the absolute
transparency. In a warm plasma case, the excitation of the propagating
longitudinal (electrostatic) modes becomes possible. We demonstrate that these
longitudinal excitations facilitate the total transparency of an opaque plasma
slab creating additional resonances in the transmission property of the system.


title:
A simple model of reactor cores for reactor neutrino flux calculations
  for the KamLAND experiment

abstract:
  KamLAND is a reactor neutrino oscillation experiment with a very long
baseline. This experiment successfully measured oscillation phenomena of
reactor antineutrinos coming mainly from 53 reactors in Japan. In order to
extract the results, it is necessary to accurately calculate time-dependent
antineutrino spectra from all the reactors. A simple model of reactor cores and
code implementing it were developed for this purpose. This paper describes the
model of the reactor cores used in the KamLAND reactor analysis.


title: On the enhancement of nuclear reaction rates in high-temperature plasma

abstract:
  We argue that the Maxwellian approximation can essentially underestimate the
rates of some nuclear reactions in hot plasma under conditions very close to
thermal equilibrium. This phenomenon is demonstrated explicitly on the example
of reactions in self-sustained DT fusion plasma with admixture of light
elements X = Li, Be, C. A kinetic analysis shows that the reactivity
enhancement results from non-Maxwellian knock-on perturbations of ion
distributions caused by close collisions with energetic fusion products. It is
found that although the fraction of the knock-on ions is small, these particles
appreciably affect the D+X and T+X reaction rates. The phenomenon discussed is
likely to have general nature and can play role in other laboratory and
probably astrophysical plasma processes.


title:
Persistence of small-scale anisotropy of magnetic turbulence as observed
  in the solar wind

abstract:
  The anisotropy of magnetophydrodynamic turbulence is investigated by using
solar wind data from the Helios 2 spacecraft. We investigate the behaviour of
the complete high-order moment tensors of magnetic field increments and we
compare the usual longitudinal structure functions which have both isotropic
and anisotropic contributions, to the fully anisotropic contribution. Scaling
exponents have been extracted by an interpolation scaling function. Unlike the
usual turbulence in fluid flows, small-scale magnetic fluctuations remain
anisotropic. We discuss the radial dependence of both anisotropy and
intermittency and their relationship.


title: Wire Compensation of Parasitic Crossings in DAFNE

abstract:
  Long-range beam-beam interactions (parasitic crossings) are one of the main
luminosity performance limitations for the Frascati e+e- Phi-factory DAFNE. In
particular, the parasitic crossings lead to a substantial lifetime reduction of
both beams in collision. This puts a limit on the maximum storable current and,
as a consequence, on the achievable peak and integrated luminosity. In order to
alleviate the problem numerical and experimental studies of the parasitic
crossings compensation with current-carrying wires have been performed at
DAFNE. Two such wires have been installed at both ends of the KLOE interaction
region. Switching on the wires in agreement with the numerical predictions,
improvement in the lifetime of the 'weak' beam (positrons) has been obtained at
the maximum current of the 'strong' one (electrons) without luminosity loss. In
this paper we describe the parasitic crossings effects in DAFNE, summarize the
results of numerical simulations on their compensation with the wires and
discuss the experimental measurements and observations.


title: Resonant transparency of materials with negative permittivity

abstract:
  It is shown that the transparency of opaque material with negative
permittivity exhibits resonant behavior. The resonance occurs as a result of
the excitation of the surface waves at slab boundaries. Dramatic field
amplification of the incident evanescent fields at the resonance improves the
resolution of the the sub-wavelength imaging system (superlens). A finite
thickness slab can be totally transparent to a \textit{p}-polarized obliquely
incident electromagnetic wave for certain values of the incidence angle and
wave frequency corresponding to the excitation of the surface modes. At the
resonance, two evanescent waves have a finite phase shift providing non-zero
energy flux through the non-transparent region.


title: Dynamical change of Pareto index in Japanese land prices

abstract:
  We investigate the dynamical behavior in the large scale region of
non-equilibrium systems, by employing data on the assessed value of land in
1983 -- 2006 Japan. In the system we find the detailed quasi-balance, which has
the symmetry: x_1 -> a {x_2}^{\theta} (x_1 and x_2 are two successive land
prices). By using the detailed quasi-balance and Gibrat's law, we derive
Pareto's law with varying Pareto index annually. The parameter \theta
corresponds with the ratio of Pareto indices (\mu_1 + 1)/(\mu_2 + 1), and the
relation is confirmed in the empirical data nicely.


title: Circular and helical equilibrium solutions of inhomogeneous rods

abstract:
  Real filaments are not perfectly homogeneous. Most of them have various
materials composition and shapes making their stiffnesses not constant along
the arclength. We investigate the existence of circular and helical equilibrium
solutions of an intrinsically straight rod with varying bending and twisting
stiffnesses, within the framework of the Kirchhoff model. The planar ring
equilibrium solution only exists for a rod with a given form of variation of
the bending stiffness. We show that the well known circular helix is not an
equilibrium solution of the static Kirchhoff equations for a rod with non
constant bending stiffness. Our results may provide an explanation for the
variation of the curvature seen in small closed DNAs immersed in a solution
containing Zn^{2+}, and in the DNA wrapped around a nucleosome.


title:
Microstrip antenna miniaturization using partial dielectric material
  filling

abstract:
  In this paper we study microstrip antenna miniaturization using partial
filling of the antenna volume with dielectric materials. An analytical
expression is derived for the quality factor of an antenna loaded with a
combination of two different materials. This expression can be used to optimize
the filling pattern for the design that most efficiently retains the impedance
bandwidth after size reduction. Qualitative design rules are given, and a
miniaturization example is provided where the antenna performance is compared
for different filling patterns. Results given by the analytical model are
verified with numerical simulations and experiments.
  Key words: Microstrip antenna, miniaturization, partial filling, impedance
bandwidth, quality factor.


title: Weighted Assortative And Disassortative Networks Model

abstract:
  Real-world networks process structured connections since they have
non-trivial vertex degree correlation and clustering. Here we propose a toy
model of structure formation in real-world weighted network. In our model, a
network evolves by topological growth as well as by weight change. In addition,
we introduce the weighted assortativity coefficient, which generalizes the
assortativity coefficient of a topological network, to measure the tendency of
having a high-weighted link between two vertices of similar degrees. Network
generated by our model exhibits scale-free behavior with a tunable exponent.
Besides, a few non-trivial features found in real-world networks are reproduced
by varying the parameter ruling the speed of weight evolution. Most
importantly, by studying the weighted assortativity coefficient, we found that
both topologically assortative and disassortative networks generated by our
model are in fact weighted assortative.


title: Negative-index metamaterial at 780 nm wavelength

abstract:
  We further miniaturize a recently established silver-based negative-index
metamaterial design. By comparing transmittance, reflectance and
phase-sensitive time-of-flight experiments to theory, we infer a real part of
the refractive index of -0.6 at 780 nm wavelength -- which is visible in the
laboratory.


title:
The Physical Reality Underlying the Relativistic Mechanics and the
  Gravitational Interaction

abstract:
  In the present paradigm the space is filled with very high flux of very small
quanta whose wavelength equals the Planck's length. The quantum energy is very
small, so the relevant Planck constant ho is much smaller than the usual h.
This physical paradigm imposes to the motion the conservation of energy and
momentum, as well as the laws of the relativistic mechanics. The strong version
of the equivalence principle, which requires both inertia and gravitation come
from a unique phenomenon, is the relevant test to verify the physical reality
of the cosmic quanta. Through Compton's interaction each quantum colliding two
masses gives them a little momentum which produces a newtonian force pushing
the masses each towards other. The constant G depends on the quanta
characteristics, so the Newton's gravitational mass does no longer holds. The
new gravitational force of stars depends on the reducing quantum energy, so G
multiplies by a gravity factor (greater than 1) depending on the star density.
The highest number (200-300) pertains to the neutron stars, which increment
notably their accretion capacity. This property may explain the mistery of the
obscure supermassive bodies whose gravitational effects rise up to 3.7 million
times the Sun effects. Current theories do not give a convincing explanation of
this phenomenon.


title: On the Available Lunar and Solar Eclipses and Babylonian Chronology

abstract:
  The recently shown two premises (Gurzadyan 2000), i.e. the absence of 56/64
year Venus cycle constraints, at the importance of the 8-year cycle in the
Venus Tablet, stimulated new studies on the Chronology of the Ancient Near East
(2nd millennium BC). The analysis by B.Banjevic using both premises, however,
did not provide anchors of strenght similar to those of Ur III eclipses, while
available solar eclipses lack unambiguous links to historical events. The
Ultra-Low chronology (Gasche et al 1998), therefore, has to be considered as
currently the one most reliably based on ancient astronomical records.


title: Catalyzing Fusion with Relativistic Electrons

abstract:
  The idea here is to use large relative velocities of electrons and nuclei in
accelerator beams to increase the probability of fusion. The function of the
electrons is to both screen the positive charge and to produce an increased
parallel pinching current. The increase in reaction probability is estimated
using the Darwin magnetic interaction energy approach.


title:
Clusters or networks of economies? A macroeconomy study through GDP
  fluctuation correlations

abstract:
  We follow up on the study of correlations between GDP's of rich countries. We
analyze web-downloaded data on GDP that we use as individual wealth signatures
of the country economical state. We calculate the yearly fluctuations of the
GDP. We look for forward and backward correlations between such fluctuations.
The system is represented by an evolving network, nodes being the GDP
fluctuations (or countries) at different times.
  In order to extract structures from the network, we focus on filtering the
time delayed correlations by removing the least correlated links. This
percolation idea-based method reveals the emergence of connections, that are
visualized by a branching representation. Note that the network is made of
weighted and directed links when taking into account a delay time. Such a
measure of collective habits does not fit the usual expectations defined by
politicians or economists.


title:
Effective-range description of a Bose gas under strong one- or
  two-dimensional confinement

abstract:
  We point out that theories describing s-wave collisions of bosonic atoms
confined in one- or two-dimensional geometries can be extended to much tighter
confinements than previously thought. This is achieved by replacing the
scattering length by an energy-dependent scattering length which was already
introduced for the calculation of energy levels under 3D confinement. This
replacement accurately predicts the position of confinement-induced resonances
in strongly confined geometries.


title: Time-frequency Domain Analogues of Phase Space Sub-Planck Structures

abstract:
  We present experimental data of the frequency resolved optical gating (FROG)
measurements of light pulses revealing interference features corresponding to
sub-Planck structures in phase space. For superpositions of pulses a small,
sub-Fourier shift in the carrier frequency leads to a state orthogonal to the
initial one, although in the representation of standard time-frequency
distributions these states seem to have a nonvanishing overlap.


title:
Speed-up and slow-down collisions in laser-induced nonsequential
  multiple ionization

abstract:
  We investigate laser induced nonsequential multiple ionization using a simple
statistical model in which an electron recollides inelastically with its parent
ion. In this collision, it thermalizes with the remaining $N-1$ bound electrons
within a time interval $\Delta t$. Subsequently, all the $N$ electrons leave.
We address the question of how the above time delays influence the individual
contributions from the orbits in which the first electron, upon return, is
accelerated or decelerated by the field, respectively, to the ion momentum
distributions. In both cases, the time delays modify the drift momenta obtained
by the $N$ electrons when they reach the continuum at $t+\Delta t$, by moving
such times towards or away from a crossing of the electric field. The
contributions from both types of collisions are influenced in distinct ways,
and the interplay between such trends determines the widths and the peak
momenta of the distributions. Specifically in the few-cycle pulse case, we also
show that such time delays do not affect the shapes of the momentum
distributions in a radical fashion. Hence, even with a thermalization time
$\Delta t$, nonsequential multiple ionization could in principle be used for
absolute-phase diagnosis.


title: Equilibrium study of Protein/DNA Complexes from Crystal Structure Data

abstract:
  From the crystal structure data and using the concept of equilbrium
statistical mechanics we show how to calculate the thermodynamics of
protein/DNA complexes. We apply the method to the TATA-box binding protein
(TBP)/TATA sequence complex. We have estimated the change in free energy and
entropy for each of the base pair (bp). The local rigidity of the DNA is
estimated from the curvature of the free energy. We also estimate the free
energy gain of the protein due to bond formation with a particular bp. We thus
figure out the bps responsible for specific binding.


title: Black hole in a waveguide: Hawking radiation or self-phase modulation?

abstract:
  Recently it was suggested that Hawking radiation may be observed in a
nonlinear electromagnetic waveguide upon propagation of an optical pulse. We
show that the spectral characteristics of the Hawking effect in such a
waveguide are indistinguishable from the well-known effect of frequency
broadening of an optical pulse due to self-phase modulation. Furthermore, we
derive an estimate on the critical optical power at which Hawking effect is
dominated by the self-phase modulation. It appears that optical experiments
reported so far are clearly dominated by self-phase modulation.


title: Electrostatic internal energy using the method of images

abstract:
  For several configurations of charges in the presence of conductors, the
method of images permits us to obtain some observables associated with such a
configuration by replacing the conductors with some image charges. However,
simple inspection shows that the potential energy associated with both systems
does not coincide. Nevertheless, it can be shown that for a system of a
grounded or neutral conductor and a distribution of charges outside, the
external potential energy associated with the real charge distribution embedded
in the field generated by the set of image charges is twice the value of the
internal potential energy associated with the original system. This assertion
is valid for any size and shape of the conductor, and regardless of the
configuration of images required. In addition, even in the case in which the
conductor is not grounded nor neutral, it is still possible to calculate the
internal potential energy of the original configuration through the method of
images. These results show that the method of images could also be useful for
calculations of the internal potential energy of the original system.


title: High-Frequency Acoustic Sediment Classification in Shallow Water

abstract:
  A geoacoustic inversion technique for high-frequency (12 kHz) multibeam sonar
data is presented as a means to classify the seafloor sediment in shallow water
(40--300 m). The inversion makes use of backscattered data at a variety of
grazing angles to estimate mean grain size. The need for sediment type and the
large amounts of multibeam data being collected with the Naval Oceanographic
Office's Simrad EM 121A systems, have fostered the development of algorithms to
process the EM 121A acoustic backscatter into maps of sediment type. The APL-UW
(Applied Physics Laboratory at the University of Washington) backscattering
model is used with simulated annealing to invert for six geoacoustic
parameters. For the inversion, three of the parameters are constrained
according to empirical correlations with mean grain size, which is introduced
as an unconstrained parameter. The four unconstrained (free) parameters are
mean grain size, sediment volume interaction, and two seafloor roughness
parameters. Acoustic sediment classification is performed in the Onslow Bay
region off the coast of North Carolina using data from the 12kHz Simrad EM 121A
multibeam sonar system. Raw hydrophone data is beamformed into 122 beams with a
120-degree swath on the ocean floor, and backscattering strengths are
calculated for each beam and for each ping. Ground truth consists of 68 grab
samples in the immediate vicinity of the sonar survey, which have been analyzed
for mean grain size. Mean grain size from the inversion shows 90\% agreement
with the ground truth and may be a useful tool for high-frequency acoustic
sediment classification in shallow water.


title: Realization of Woodpile Structure Using Optical Interference Holography

abstract:
  We report the use of a (4+1)-beam optical interference holography technique
to fabricate woodpile structures in photo-resists. The configuration consists
of 4 linear polarized side beams arranged symmetrically around a circular
polarized central beam with all the beams from the same half space, making it
easily accessible experimentally. The fabricated woodpile structures are in
good agreement with model simulations. Furthermore, woodpiles with the diamond
symmetry are also obtained by exploiting the deformations of the photo-resists.
Directional bandgaps in the visible range are also observed for the samples
with and without the correct stacking of the woodpile structures.


title: Computational Euler History

abstract:
  A new pseudospectral calculation of collapsing Euler vortices \cite{HouLi06}
has called into question the long-term conclusions of singular behavior
described earlier in \cite{Kerr93,Kerr05}. This review is designed to: improve
the discussion of the detailed analysis of one test initial condition designed
find sources of errors, to compare that with calculations showing no evidence
of a singularity, and to document two sets of discussions. Those prior to 1993
between competing teams. And recent discussions of what is needed to reach more
convincing conclusions.


title:
Multiple optical traps from a single laser beam using a mechanical
  element

abstract:
  The use of a wire mesh facilitates creation of multiple optical traps for
manipulation of small micron or sub-micron particles. Such an array of optical
traps can be easily controlled. The trap that is formed in this manner is a
continuous trap; it obviates the need to time share a laser beam among a set of
positions, as is presently done in conventional multiple traps.


title:
What do we learn from correlations of local and global network
  properties?

abstract:
  In complex networks a common task is to identify the most important or
"central" nodes. There are several definitions, often called centrality
measures, which often lead to different results. Here we study extensively
correlations between four local and global measures namely the degree, the
shortest-path-betweenness, the random-walk betweenness and the subgraph
centrality on different random-network models like Erdos-Renyi, Small-World and
Barabasi-Albert as well as on different real networks like metabolic pathways,
social collaborations and computer networks. Correlations are quite different
between the real networks and the model networks questioning whether the models
really reflect all important properties of the real world.


title:
Analysis of a Japan government intervention on the domestic agriculture
  market

abstract:
  We investigate an economic system in which one large agent - the Japan
government changes the environment of numerous smaller agents - the Japan
agriculture producers by indirect regulation of prices of agriculture goods.
The reason for this intervention was that before the oil crisis in 1974 Japan
agriculture production prices exhibited irregular and large amplitude changes.
By means of analysis of correlations and a combination of singular spectrum
analysis (SSA), principal component analysis (PCA), and time delay phase space
construction (TDPSC) we study the influence of the government measures on the
domestic piglet prices and production in Japan. We show that the government
regulation politics was successful and leaded (i) to a decrease of the
nonstationarities and to increase of predictability of the piglet price; (ii)
to a coupling of the price and production cycles; (iii) to increase of
determinism of the dynamics of the fluctuations of piglet price around the year
average price. The investigated case is an example confirming the thesis that a
large agent can change in a significant way the environment of the small agents
in complex (economic or financial) systems which can be crucial for their
survival or extinction.


title: The intersecting brane world

abstract:
  The scales of the Standard Model correspond to the positions of domain wall
intersections on a straight line in a noncompact two-dimensional extra space.
The domain walls partition an Anti-de Sitter spacetime. We show that domain
wall intersections mark the orthogonal intersections of 1-cycles winding around
a rectangular compact space and a hierarchy of subspaces, and that the
noncompact extra space of the model is a covering space. 4-branes wrap 1-cycles
of the compact spaces and intersect orthogonally in 3-branes, upon which the
particles propagate. We show that particles are located precisely at domain
wall intersections in the covering space.


title:
Adiabatic Approximation of the Correlation Function in the
  Density-Functional Treatment of Ionization Processes

abstract:
  The ionization of a one-dimensional model Helium atom in short laser pulses
using time-dependent density functional theory is investigated. We calculate
ionization probabilities as a function of laser intensity by approximating the
correlation function of the system adiabatically with an explicit dependence on
the fractional number of bound electrons. For the correlation potential we take
the derivative discontinuity at integer numbers of bound electrons explicitly
into account. This approach reproduces ionization probabilities from the
solution of the time-dependent Schroedinger equation, in particular the
so-called "knee" due to nonsequential ionization.


title: GLD Detector Outline Document

abstract:
  The GLD is a detector for the experiment at the International Linear Collider
(ILC). It consists of a large calorimeter and a gaseous central tracker placed
in a moderate magnetic field, both electro-magnetic and hadron calorimeters
being placed inside the magnetic coil to have enough hermeticity and good jet
energy resolution. The outline of the GLD is presented.


title: Cooperation Networks: Endogeneity and Complexity

abstract:
  Insights from the Complex Systems literature are employed to develop a
computational model of truly endogenous strategic network formation. Artificial
Adaptive Agents, implemented as Finite State Automata (FSA), play a modified
two-player IPD game with an option to further develop the interaction space as
part of their strategy. Several insights result from this minor modification:
first, I find that network formation is a necessary condition for cooperation
to be sustainable but that both the frequency of interaction and the degree to
which edge formation impacts agent mixing are both necessary conditions for
cooperative networks. Second, within the FSA-modified IPD frame-work, a rich
ecology of agents and network topologies is observed and described. Third, the
system dynamics are investigated and reveal that initially simple dynamics with
small interaction length between agents gives way to complex, a-periodic
dynamics with self-organized critical properties when interaction lengths are
increased by a single step.


title:
The effect of integration time on fluctuation measurements: calibrating
  an optical trap in the presence of motion blur

abstract:
  Dynamical instrument limitations, such as finite detection bandwidth, do not
simply add statistical errors to fluctuation measurements, but can create
significant systematic biases that affect the measurement of steady-state
properties. Such effects must be considered when calibrating ultra-sensitive
force probes by analyzing the observed Brownian fluctuations. In this article,
we present a novel method for extracting the true spring constant and diffusion
coefficient of a harmonically confined Brownian particle that extends the
standard equipartition and power spectrum techniques to account for video-image
motion blur. These results are confirmed both numerically with a Brownian
dynamics simulation, and experimentally with laser optical tweezers.


title: DNS of bifurcations in an air-filled rotating baroclinic annulus

abstract:
  Three-dimensional Direct Numerical Simulation (DNS) on the nonlinear dynamics
and a route to chaos in a rotating fluid subjected to lateral heating is
presented here and discussed in the context of laboratory experiments in the
baroclinic annulus. Following two previous preliminary studies by Maubert and
Randriamampianina, the fluid used is air rather than a liquid as used in all
other previous work. This study investigated a bifurcation sequence from the
axisymmetric flow to a number of complex flows. The transition sequence, on
increase of the rotation rate, from the axisymmetric solution via a steady,
fully-developed baroclinic wave to chaotic flow followed a variant of the
classical quasi-periodic bifurcation route, starting with a subcritical Hopf
and associated saddle-node bifurcation. This was followed by a sequence of two
supercritical Hopf-type bifurcations, first to an amplitude vacillation, then
to a three-frequency quasi-periodic modulated amplitude vacillation (MAV), and
finally to a chaotic MAV\@. In the context of the baroclinic annulus this
sequence is unusual as the vacillation is usually found on decrease of the
rotation rate from the steady wave flow. Further transitions of a steady wave
with a higher wave number pointed to the possibility that a barotropic
instability of the side wall boundary layers and the subsequent breakdown of
these barotropic vortices may play a role in the transition to structural
vacillation and, ultimately, geostrophic turbulence.


title:
Electrical controlled rheology of a suspension of weakly conducting
  particles in dielectric liquid

abstract:
  The properties of suspensions of fine particles in dielectric liquid
(electrorheological fluids) subjected to an electric field lead to a drastic
change of the apparent viscosity of the fluid. For high applied fields (~ 3-5
kV/mm) the suspension congeals to a solid gel (particles fibrillate span the
electrode gap) having a finite yield stress. For moderate fields the viscosity
of the suspension is continuously controlled by the electric field strength. We
have roposed that in DC voltage the field distribution in the solid (particles)
and liquid phases of the suspension and so the attractive induced forces
between particles and the yield stress of the suspension are controlled by the
conductivities of the both materials. In this paper we report investigation and
results obtained with nanoelectrorheological suspensions: synthesis of coated
nanoparticles (size ~ 50 to 600 nm, materials Gd2O3:Tb, SiOx...), preparation
of ER fluids (nanoparticles mixed in silicone oil), electrical and rheological
characterization of the ER fluids. We also propose a possible explanation of
the enhanced ER effect (giant ER fluids) taking into account the combined
effects of the (nano)size of the particles, the Van der Waals forces between
particles in contact and the electrostatic pressure in a very thin layer of
insulating liquid.


title: An indicator for community structure

abstract:
  An indicator for presence of community structure in networks is suggested. It
allows one to check whether such structures can exist, in principle, in any
particular network, without a need to apply computationally cost algorithms. In
this way we exclude a large class of networks that do not possess any community
structure.


title:
Turbulence characteristics of the B\"{o}dewadt layer in a large shrouded
  rotor-stator system

abstract:
  A three-dimensional direct numerical simulation (3D DNS) is performed to
describe the turbulent flow in an enclosed rotor-stator cavity characterized by
a large aspect ratio $G=(b-a)/h=18.32$ and a small radius ratio $a/b=0.15$ ($a$
and $b$ the inner and outer radii of the rotating disk and $h$ the interdisk
spacing). Recent comparisons with velocity measurements have shown that, for
the rotational Reynolds number $Re=\Omega b^2/\nu=95000$ ($\Omega$ the rate of
rotation of the rotating disk and $\nu$ the kinematic viscosity of water) under
consideration, the stator boundary layer is 3D turbulent and the rotor one is
still laminar. Budgets for the turbulence kinetic energy are here presented and
highlight some characteristic features of the effect of rotation on turbulence.
A quadrant analysis of conditionally averaged velocities is also performed to
identify the contributions of different events (ejections and sweeps) on the
Reynolds shear stress.


title:
One-dimensional ultrasound propagation at stratified gas: Gross-Jackson
  model

abstract:
  The system of hydrodynamic-type equations, derived by two-side distribution
function for a stratified gas in gravity field is applied to a problem of
ultrasound. The theory is based on Gross-Jackson kinetic equation, which
solution is built by means of locally equilibrium distribution function with
different local parameters for molecules moving "up"and "down". The linearized
version of the obtained system is studied and compared with other results and
experiments at arbitrary Knudsen numbers. The problem of a generation by a
moving plane in a rarefied gas is explored. The WKB solutions for ultrasound in
a stratified medium are constructed in explicit form, evaluated and plotted.


title:
Investigation of phase separation within the generalized Lin-Taylor
  model for a binary liquid mixture of large hexagonal and small triangular
  particles

abstract:
  The generalized Lin-Taylor model defined on the hexagonal lattice is used to
investigate the phase separation in an asymmetric binary liquid mixture
consisting of large A (hexagons) and small B (triangles) particles. By
considering interaction energies between A-A and A-B pairs of particles that
occupy nearest-neighbour cells of the hexagonal lattice, we have derived an
exact solution for the considered model system having established a mapping
correspondence with the two-dimensional Ising model on its dual triangular
lattice. Altogether, six different types of coexistence curves including those
with reentrant miscibility regions (i.e. closed-loop coexistence curves) were
found in dependence on the relative strength between both coupling constants.


title: Particle tracking in the ILC extraction lines with DIMAD and BDSIM

abstract:
  The study of beam transport is of central importance to the design and
performance assessment of modern particle accelerators. In this paper, we
benchmark two contemporary codes, DIMAD and BDSIM, the latter being a
relatively new tracking code built within the framework of GEANT4. We consider
both the 20 mrad and 2 mrad extraction lines of the 500 GeV International
Linear Collider (ILC) and we perform particle tracking studies of heavily
disrupted post-collision electron beams. We find that the two codes give an
almost equivalent description of the beam transport.


title: Dynamics and (de)localization in a one-dimensional tight-binding chain

abstract:
  A simple tight-binding model is used to illustrate how the time dependence of
a state vector can be obtained from all the eigenvalues and eigenvectors of the
Hamiltonian. The behavior of the eigenvalues and eigenvectors is studied for
various parameters and allows us to study scattering-like events, impurity
states, and localization in disordered systems.


title:
Benchmarking of Tracking Codes (BDSIM/DIMAD) using the ILC Extraction
  Lines

abstract:
  The study of beam transport is of central importance to the design and
performance assessment of modern particle accelerators. In this work, we
benchmark two contemporary codes - DIMAD and BDSIM, the latter being a
relatively new tracking code built within the framework of GEANT4. We consider
both the 20 mrad and 2 mrad extraction lines of the International Linear
Collider (ILC) and we perform tracking studies of heavily disrupted
post-collision electron beams. We find that the two codes mostly give an
equivalent description of the beam transport.


title: Kelly Criterion revisited: optimal bets

abstract:
  Kelly criterion, that maximizes the expectation value of the logarithm of
wealth for bookmaker bets, gives an advantage over different class of
strategies. We use projective symmetries for a explanation of this fact.
Kelly's approach allows for an interesting financial interpretation of the
Boltzmann/Shannon entropy. A "no-go" hypothesis for big investors is suggested.


title:
Non-extensive Behavior of a Stock Market Index at Microscopic Time
  Scales

abstract:
  This paper presents an empirical investigation of the intraday Brazilian
stock market price fluctuations, considering q-Gaussian distributions that
emerge from a non-extensive statistical mechanics. Our results show that, when
returns are measured over intervals less than one hour, the empirical
distributions are well fitted by q-Gaussians with exponential damped tails.
Scaling behavior is also observed for these microscopic time intervals. We find
that the time evolution of the distributions is according to a super diffusive
q-Gaussian stationary process within a nonlinear Fokker-Planck equation. This
regime breaks down due to the exponential fall-off of the tails, which in turn,
governs the transient dynamics to the long-term macroscopic Gaussian regime.
Our results suggest that this modeling provides a framework for the description
of the dynamics of stock markets intraday price fluctuations.


title:
State-to-state rotational transitions in H$_2$+H$_2$ collisions at low
  temperatures

abstract:
  We present quantum mechanical close-coupling calculations of collisions
between two hydrogen molecules over a wide range of energies, extending from
the ultracold limit to the super-thermal region. The two most recently
published potential energy surfaces for the H$_2$-H$_2$ complex, the so-called
DJ (Diep and Johnson, 2000) and BMKP (Boothroyd et al., 2002) surfaces, are
quantitatively evaluated and compared through the investigation of rotational
transitions in H$_2$+H$_2$ collisions within rigid rotor approximation. The
BMKP surface is expected to be an improvement, approaching chemical accuracy,
over all conformations of the potential energy surface compared to previous
calculations of H$_2$-H$_2$ interaction. We found significant differences in
rotational excitation/de-excitation cross sections computed on the two surfaces
in collisions between two para-H$_2$ molecules. The discrepancy persists over a
large range of energies from the ultracold regime to thermal energies and
occurs for several low-lying initial rotational levels. Good agreement is found
with experiment (Mat\'e et al., 2005) for the lowest rotational excitation
process, but only with the use of the DJ potential. Rate coefficients computed
with the BMKP potential are an order of magnitude smaller.


title: Broadband SBS Slow Light in an Optical Fiber

abstract:
  We investigate slow-light via stimulated Brillouin scattering in a room
temperature optical fiber that is pumped by a spectrally broadened laser.
Broadening the spectrum of the pump field increases the linewidth
$\Delta\omega_p$ of the Stokes amplifying resonance, thereby increasing the
slow-light bandwidth. One physical bandwidth limitation occurs when the
linewidth becomes several times larger than the Brillouin frequency shift
$\Omega_B$ so that the anti-Stokes absorbing resonance cancels out
substantially the Stokes amplifying resonance and hence the slow-light effect.
We find that partial overlap of the Stokes and anti-Stokes resonances can
actually lead to an enhancement of the slow-light delay - bandwidth product
when $\Delta\omega_p \simeq 1.3 \Omega_B$. Using this general approach, we
increase the Brillouin slow-light bandwidth to over 12 GHz from its nominal
linewidth of $\sim$30 MHz obtained for monochromatic pumping. We controllably
delay 75-ps-long pulses by up to 47 ps and study the data pattern dependence of
the broadband SBS slow-light system.


title:
Nonlinear propagation of broadband intense electromagnetic waves in an
  electron-positron plasma

abstract:
  A kinetic equation describing the nonlinear evolution of intense
electromagnetic pulses in electron-positron (e-p) plasmas is presented. The
modulational instability is analyzed for a relativistically intense partially
coherent pulse, and it is found that the modulational instability is inhibited
by the spectral pulse broadening. A numerical study for the one-dimensional
kinetic photon equation is presented. Computer simulations reveal a
Fermi-Pasta-Ulam-like recurrence phenomena for localized broadband pulses. The
results should be of importance in understanding the nonlinear propagation of
broadband intense electromagnetic pulses in e-p plasmas in laser-plasma systems
as well as in astrophysical plasma settings.


title:
Tamm states in one dimensional photonic crystals containing left-handed
  materials

abstract:
  We present a theoretical study of electromagnetic surface waves localized at
an interface separating a conventional uniform medium and a semi-infinite 1-D
photonic crystal made of alternate left-handed metamaterial and right-handed
material which we refer to as left-handed photonic crystal. We find novel type
of surface mode's structure, the so-called surface Tamm states and demonstrate
that the presence of metamaterial in the photonic crystal structure allows for
a flexible control of the dispersion properties of surface states, and can
support the Tamm states with a backward energy flow and a vortex-like
structure.


title: Dielectronic Recombination Rates In Astrophysical Plasmas

abstract:
  In this work we introduce a new expression of the plasma Dielecronic
Recombination (DR) rate as a function of the temperature, derived assuming a
small deformation of the Maxwell-Boltzmann distribution and containing
corrective factors, in addition to the usual exponential behaviour, caused by
non-linear effects in slightly non ideal plasmas. We then compare the
calculated DR rates with the experimental DR fits in the low temperature
region.


title: The 2 mrad crossing-angle ILC interaction region and extraction line

abstract:
  A complete optics design for the 2mrad crossing angle interaction region and
extraction line was presented at Snowmass 2005. Since this time, the design
task force has been working on developing and improving the performance of the
extraction line. The work has focused on optimising the final doublet
parameters and on reducing the power losses resulting from the disrupted beam
transport. In this paper, the most recent status of the 2mrad layout and the
corresponding performance are presented.


title: Adapting to heterogeneous comfort levels

abstract:
  We study the learning dynamics of agents who adapt to heterogeneous comfort
levels in the context of an El-Farol type game, and show that even an
infinitesimal degree of heterogeneity in the resource levels leads to a
significant reduction of the fluctuations of the collective action, and removes
the phase transition observed in models with homogeneous comfort level. Our
analysis is based on dynamical methods of disordered systems theory, in
particular on a generating functional approach, and confirmed by numerical
experiments. We also report on simulations of a system in which the comfort
levels fluctuate in time, and point out crucial differences between models in
which the comfort levels of the agents fluctuate collectively and individually
respectively. Finally we comment on a possible characterisation of El-Farol and
Minority Games according to the presence or absence of ergodicity-breaking
phase transitions at infinite integrated response.


title: The matrix rate of return

abstract:
  In this paper we give definitions of matrix rates of return which do not
depend on the choice of basis describing baskets. We give their economic
interpretation. The matrix rate of return describes baskets of arbitrary type
and extends portfolio analysis to the complex variable domain. This allows us
for simultaneous analysis of evolution of baskets parameterized by complex
variables in both continuous and discrete time models.


title:
Bayesian Analysis of the Conditional Correlation Between Stock Index
  Returns with Multivariate SV Models

abstract:
  In the paper we compare the modelling ability of discrete-time multivariate
Stochastic Volatility models to describe the conditional correlations between
stock index returns. We consider four trivariate SV models, which differ in the
structure of the conditional covariance matrix. Specifications with zero,
constant and time-varying conditional correlations are taken into account. As
an example we study trivariate volatility models for the daily log returns on
the WIG, SP500, and FTSE100 indexes. In order to formally compare the relative
explanatory power of SV specifications we use the Bayesian principles of
comparing statistic models. Our results are based on the Bayes factors and
implemented through Markov Chain Monte Carlo techniques. The results indicate
that the most adequate specifications are those that allow for time-varying
conditional correlations and that have as many latent processes as there are
conditional variances and covariances. The empirical results clearly show that
the data strongly reject the assumption of constant conditional correlations.


title: Effect of an Optical Negative Index Thin Film on Optical Bistability

abstract:
  We investigate nonlinear transmission in a layered structure consisting of a
slab of positive index material (PIM) with Kerr-type nonlinearity and a
sub-wavelength layer of linear negative index material (NIM) sandwiched between
semi-infinite linear dielectrics. We find that a thin layer of NIM leads to
significant changes in the hysteresis width when the nonlinear slab is
illuminated at an angle near that of total internal reflection. Unidirectional
diode-like transmission with enhanced operational range is demonstrated. These
results may be useful for NIMs characterization and for designing novel NIMs
based devices.


title:
Impact of Unexpected Events, Shocking News and Rumours on Foreign
  Exchange Market Dynamics

abstract:
  We analyze the dynamical response of the world's financial community to
various types of unexpected events, including the 9/11 terrorist attacks as
they unfolded on a minute-by-minute basis. We find that there are various
'species' of news, characterized by how quickly the news get absorbed, how much
meaning and importance is assigned to it by the community, and what subsequent
actions are then taken. For example, the response to the unfolding events of
9/11 shows a gradual collective understanding of what was happening, rather
than an immediate realization. For news items which are not simple economic
statements, and hence whose implications are not immediately obvious, we
uncover periods of collective discovery during which collective opinions seem
to oscillate in a remarkably synchronized way. In the case of a rumour, our
findings also provide a concrete example of contagion in inter-connected
communities. Practical applications of this work include the possibility of
producing selective newsfeeds for specific communities, based on their likely
impact.


title: Detection of Complex Networks Modularity by Dynamical Clustering

abstract:
  Based on cluster de-synchronization properties of phase oscillators, we
introduce an efficient method for the detection and identification of modules
in complex networks. The performance of the algorithm is tested on computer
generated and real-world networks whose modular structure is already known or
has been studied by means of other methods. The algorithm attains a high level
of precision, especially when the modular units are very mixed and hardly
detectable by the other methods, with a computational effort ${\cal O}(KN)$ on
a generic graph with $N$ nodes and $K$ links.


title:
How Do Output Growth Rate Distributions Look Like? Some Time-Series
  Evidence on OECD Countries

abstract:
  This paper investigates the statistical properties of within-country GDP and
industrial production (IP) growth rate distributions. Many empirical
contributions have recently pointed out that cross-section growth rates of
firms, industries and countries all follow Laplace distributions. In this work,
we test whether also within-country, time-series GDP and IP growth rates can be
approximated by tent-shaped distributions. We fit output growth rates with the
exponential-power (Subbotin) family of densities, which includes as particular
cases both the Gaussian and the Laplace distributions. We find that, for a
large number of OECD countries including the U.S., both GDP and IP growth rates
are Laplace distributed. Moreover, we show that fat-tailed distributions
robustly emerge even after controlling for outliers, autocorrelation and
heteroscedasticity.


title:
Multiple scattering and PXR: kinematical suppression of multiple
  scattering influence on PXR and dynamical shift of diffraction peaks

abstract:
  Kinematical suppression of electron multiple scattering influence on
parametric X-ray radiation (PXR) and coherent bremsstrahlung (CBS) is
considered. Dynamical shift of diffraction peaks is predicted and discussed.


title:
Long-term memory in the Irish market (ISEQ): evidence from wavelet
  analysis

abstract:
  Researchers have used many different methods to detect the possibility of
long-term dependence (long memory) in stock market returns, but evidence is in
general mixed. In this paper, three different tests, (namely Rescaled Range
(R/S), its modified form, and the semi-parametric method (GPH)), in addition to
a new approach using the discrete wavelet transform, (DWT), have been applied
to the daily returns of five Irish Stock Exchange (ISEQ) indices. These methods
have also been applied to the volatility measures (namely absolute and squared
returns). The aim is to investigate the existence of long-term memory
properties. The indices are Overall, Financial, General, Small Cap and ITEQ and
the results of these approaches show that there is no evidence of long-range
dependence in the returns themselves, while there is strong evidence for such
dependence in the squared and absolute returns. Moreover, the discrete wavelet
transform (DWT) provides additional insight on the series breakdown. In
particular, in comparison to other methods, the benefit of the wavelet
transform is that it provides a way to study the sensitivity of the series to
increases in amplitude of fluctuations as well as changes in frequency.
Finally, based on results for these methods, in particular, those for DWT of
raw (or original), squared and absolute returns, it can be concluded that there
is strong indication for persistence in the volatilities of the emerging stock
market returns for the Irish data.


title:
Football: A Naive Approximation to the Effect of Increasing Goal Size on
  the Number of Goals

abstract:
  The effect of increasing goal mouth size on the number of goals scored in a
football match is discussed in a very preliminary and simple way, considering
elastic collisions of the ball with the posts. The result is obtained on the
basis of data taken from the Spanish Professional League, that show a high
number of shots-to-post. Surprisingly, there is a direct correlation of the
increase in goal mouth area with the increase of goals.


title: Magnetism and Magnetic Isomers in Free Chromium Clusters

abstract:
  We have used the Stern-Gerlach deflection technique to study magnetism in
chromium clusters of 20-133 atoms. Between 60 K and 100 K, we observe that
these clusters have large magnetic moments and respond superparamagnetically to
applied magnetic fields. Using superparamagnetic theory, we have determined the
moment per atom for each cluster size and find that it often far exceeds the
moment per atom present anywhere in the bulk antiferromagnetic lattice.
Remarkably, our cluster beam contains two magnetically distinguishable forms of
each cluster size with >= 34 atoms. We attribute this observation to structural
isomers.


title:
Collisionless energy absorption in the short-pulse intense laser-cluster
  interaction

abstract:
  In a previous Letter [Phys. Rev. Lett. 96, 123401 (2006)] we have shown by
means of three-dimensional particle-in-cell simulations and a simple
rigid-sphere model that nonlinear resonance absorption is the dominant
collisionless absorption mechanism in the intense, short-pulse laser cluster
interaction. In this paper we present a more detailed account of the matter. In
particular we show that the absorption efficiency is almost independent of the
laser polarization. In the rigid-sphere model, the absorbed energy increases by
many orders of magnitude at a certain threshold laser intensity. The
particle-in-cell results display maximum fractional absorption around the same
intensity. We calculate the threshold intensity and show that it is
underestimated by the common over-barrier ionization estimate.


title: On the Non-Lorentz Invariance of M.W. Evans O(3)-Symmetry Law

abstract:
  Correcting a former proof of M.W. Evans it is shown that his O(3) hypothesis
is not Lorentz invariant and hence no law of Physics.


title:
A Cell Dynamical System Model for Simulation of Continuum Dynamics of
  Turbulent Fluid Flows

abstract:
  Atmospheric flows exhibit long-range spatiotemporal correlations manifested
as the fractal geometry to the global cloud cover pattern concomitant with
inverse power-law form for power spectra of temporal fluctuations of all scales
ranging from turbulence (millimeters-seconds) to climate (thousands of
kilometers-years). Long-range spatiotemporal correlations are ubiquitous to
dynamical systems in nature and are identified as signatures of self-organized
criticality. Standard models for turbulent fluid flows in meteorological theory
cannot explain satisfactorily the observed multifractal (space-time) structures
in atmospheric flows. Numerical models for simulation and prediction of
atmospheric flows are subject to deterministic chaos and give unrealistic
solutions. Deterministic chaos is a direct consequence of round-off error
growth in iterative computations. Round-off error of finite precision
computations doubles on an average at each step of iterative computations.
Round-off error will propagate to the mainstream computation and give
unrealistic solutions in numerical weather prediction and climate models which
incorporate thousands of iterative computations in long-term numerical
integration schemes. A recently developed non-deterministic cell dynamical
system model for atmospheric flows predicts the observed self-organized
criticality as intrinsic to quantumlike mechanics governing flow dynamics.
Further, the fractal space-time structure to the stringlike atmospheric flow
trajectory is resolved into a continuum of eddies. The eddy circulations obey
Kepler third law of planetary motion and therefore eddy inertial masses obey
Newton inverse square law of gravitation on all scales from microscopic to
macroscale.


title: A Stochastic Evolutionary Growth Model for Social Networks

abstract:
  We present a stochastic model for a social network, where new actors may join
the network, existing actors may become inactive and, at a later stage,
reactivate themselves. Our model captures the evolution of the network,
assuming that actors attain new relations or become active according to the
preferential attachment rule. We derive the mean-field equations for this
stochastic model and show that, asymptotically, the distribution of actors
obeys a power-law distribution. In particular, the model applies to social
networks such as wireless local area networks, where users connect to
access-points, and peer-to-peer networks where users connect to each other. As
a proof of concept, we demonstrate the validity of our model empirically by
analysing a public log containing traces from a wireless network at Dartmouth
College over a period of three years. Analysing the data processed according to
our model, we demonstrate that the distribution of user accesses is
asymptotically a power-law distribution.


title:
Lorentz and "apparent" transformations of the electric and magnetic
  fields

abstract:
  It is recently discovered that the usual transformations of the
three-dimensional (3D) vectors of the electric and magnetic fields differ from
the Lorentz transformations (LT) (boosts) of the corresponding 4D quantities
that represent the electric and magnetic fields. In this paper, using geometric
algebra formalism, this fundamental difference is examined representing the
electric and magnetic fields by bivectors.


title: The central error of M. W. Evans ECE theory - a type mismatch

abstract:
  This note corrects an erroneous article by M.W. Evans on his GCUFT theory
which he took over in his GCUFT book. Due to Evans' bad habit of suppressing
seemingly unimportant indices type match errors occur that cannot be removed.
In addition some further errors of that article/book chapter are pointed out.


title: Neutron imaging with a Micromegas detector

abstract:
  The micropattern gaseous detector Micromegas has been developed for several
years in Saclay and presents good performance for neutron detection. A
prototype for neutron imaging has been designed and new results obtained in
thermal neutron beams are presented. Based on previous results demonstrating a
good 1D spatial resolution, a tomographic image of a multiwire cable has been
performed using a 1D Micromegas prototype. The number of pillars supporting the
micromesh is too large and leads to local losses of efficiency that distort the
tomographic reconstruction. Nevertheless, this first tomographic image achieved
with this kind of detector is very encouraging. The next worthwhile development
for neutron imaging is to achieve a bi-dimensional detector, which is presented
in the second part of this study. The purpose of measurements was to
investigate various operational parameters to optimize the spatial resolution.
Through these measurements the optimum spatial resolution has been found to be
around 160 microns (standard deviation) using Micromegas operating in double
amplification mode. Several 2D imaging tests have been carried out. Some of
these results have revealed fabrication defects that occurred during the
manufacture of Micromegas and that are limiting the full potential of the
present neutron imaging system.


title:
Evidence of Increment of Efficiency of the Mexican Stock Market Through
  the Analysis of its Variations

abstract:
  It is well known that there exist statistical and structural differences
between the stock markets of developed and emerging countries. In this work, we
present an analysis of the variations and autocorrelations of the Mexican Stock
Market index (IPC) for different periods of its historical daily data, showing
evidence that the Mexican Stock Market has been increasing its efficiency in
recent times. We have analyzed the returns autocorrelation function (ACF) and
used detrended fluctuation analysis (DFA) methods. We also analyze the
volatility of the IPC and the Dow Jones Industrial Average (DJIA) and compare
their evolution. The data samples analyzed here, correspond to daily values of
the IPC and DJIA for the period 10/30/1978 to 02/28/2006.


title:
Precision bond lengths for Rydberg Matter clusters KN (N = 19, 37, 61
  and 91) in excitation levels n = 4 - 8 from rotational radio-frequency
  emission spectra

abstract:
  Clusters of the electronically excited condensed matter Rydberg Matter (RM)
are planar and six-fold symmetric with magic numbers N = 7, 19, 37, 61 and 91.
The bond distances in the clusters are known with a precision of +- 5% both
from theory and Coulomb explosion experiments. Long series of up to 40
consecutive lines from rotational transitions in such clusters are now observed
in emission in the radio-frequency range 7-90 MHz. The clusters are produced in
five different vacuum chambers equipped with RM emitters. The most prominent
series with B = 0.9292 +- 0.0001 MHz agrees accurately with expectation (within
2%) for the planar six-fold symmetric cluster K19 in excitation level n = 4.
Other long series agree even better with K19 at n = 5 and 6. The ratio between
the interatomic distance and the theoretical electron orbit radius (the
dimensional ratio) for K19 in n = 4 is found to be 2.8470 +- 0.0003. For
clusters K19 (n = 6) and K37 (n = 7 and 8) the dimensional ratio 2.90 is the
highest value that is found, which happens to be exactly the theoretical value.
Clusters K61 and K91 in n = 5 and 6 have slightly lower dimensional ratios.
This is expected since the edge effects are smaller. Intensity alternations are
observed of approximately 7:3. The nuclear spins interact strongly with the
magnetic field from the orbiting electrons. Spin transitions are observed with
energy differences corresponding accurately (within 0.6%) to transitions with
apparent total (delta)F = -3 at excitation levels n = 5 and 6. The angular
momentum coupling schemes in the clusters are complex but well understood.


title:
Detrended fluctuation analysis for fractals and multifractals in higher
  dimensions

abstract:
  One-dimensional detrended fluctuation analysis (1D DFA) and multifractal
detrended fluctuation analysis (1D MF-DFA) are widely used in the scaling
analysis of fractal and multifractal time series because of being accurate and
easy to implement. In this paper we generalize the one-dimensional DFA and
MF-DFA to higher-dimensional versions. The generalization works well when
tested with synthetic surfaces including fractional Brownian surfaces and
multifractal surfaces. The two-dimensional MF-DFA is also adopted to analyze
two images from nature and experiment and nice scaling laws are unraveled.


title:
High-resolution, large dynamic range fiber length measurement based on
  frequency-shifted asymmetrical Sagnac interferometer

abstract:
  We propose and experimentally demonstrate a single-mode fiber length and
dispersion measurement system based on a novel frequency-shifted asymmetric
Sagnac interferometer incorporating an acousto-optic modulator (AOM). By
sweeping the driving frequency of the AOM, which is asymmetrically placed in
the Sagnac loop, the optical length of the fiber can be determined by measuring
the corresponding variation in the phase delay between the two
counter-propagating light beams. Combined with a high-resolution data
processing algorithm, this system yields a dynamic range from a few centimeters
to 60km (limited only by our availability of long fibers) with a resolution
about 1ppm for long fibers.


title:
Large-mode-number magnetohydrodynamic instability driven by sheared
  flows in a tokamak plasma with reversed central shear

abstract:
  The effect of a narrow sub-Alfvenic shear flow layer near the minimum q_min
of the tokamak safety factor profile in a configuration with reversed central
shear is analyzed. Sufficiently strong velocity shear gives rise to a broad
spectrum of fast growing Kelvin-Helmholtz (KH)-like ideal magnetohydrodynamic
(MHD) modes with dominant mode numbers m,n ~ 10. Nonlinear simulations with
finite resistivity show magnetic reconnection near ripples caused by KH-like
vortices, the formation of turbulent structures, and a flattening of the flow
profile. The KH modes are compared to double tearing modes (DTM) which dominate
at lower shearing rates. The possible application of these results in tokamaks
with internal transport barrier is discussed.