title:
Viscous heating in fluids with temperature-dependent viscosity:
  implications for magma flows

abstract:
  Viscous heating plays an important role in the dynamics of fluids with
strongly temperature-dependent viscosity because of the coupling between the
energy and momentum equations. The heat generated by viscous friction produces
a local temperature increase near the tube walls with a consequent decrease of
the viscosity which may dramatically change the temperature and velocity
profiles. These processes are mainly controlled by the Pecl\'et number, the
Nahme number, the flow rate and the thermal boundary conditions. The problem of
viscous heating in fluids was investigated in the past for its practical
interest in the polymer industry, and was invoked to explain some rheological
behaviours of silicate melts, but was not completely applied to study magma
flows. In this paper we focus on the thermal and mechanical effects caused by
viscous heating in tubes of finite lengths. We find that in magma flows at high
Nahme number and typical flow rates, viscous heating is responsible for the
evolution from Poiseuille flow, with a uniform temperature distribution at the
inlet, to a plug flow with a hotter layer near the walls. When the temperature
gradients induced by viscous heating are very pronounced, local instabilities
may occur and the triggering of secondary flows is possible. For completeness,
this paper also describes magma flow in infinitely long tubes both at steady
state and in transient phase.


title:
Hyperspherical partial wave calculation for double photoionization of
  the helium atom at 20 eV excess energy

abstract:
  Hyperspherical partial wave approach has been applied here in the study of
double photoionization of the helium atom for equal energy sharing geometry at
20 eV excess energy. Calculations have been done both in length and velocity
gauges and are found to agree with each other, with the CCC results and with
experiments and exhibit some advantages of the corresponding three particle
wave function over other wave functions in use.


title: A Note on Derivation of Rutherford Formula within Born Approximation

abstract:
  It is shown in this paper that one does not need to use just exponential
dumping factor when computing the Rutherford formula within Born approximation.
Text, which is very simple, might be of interest for physics students as well
as for physics teachers.


title: Unbiased simulation of structural transitions in calmodulin

abstract:
  We introduce an approach for performing "very long" computer simulations of
the dynamics of simplified, folded proteins. Using an alpha-carbon protein
model and a fine grid to mimic continuum computations at increased speed, we
perform unbiased simulations which exhibit many large-scale conformational
transitions at low cost. In the case of the 72-residue N-terminal domain of
calmodulin, the approach yields structural transitions between the calcium-free
and calcium-bound structures at a rate of roughly one per day on a single Intel
processor. Stable intermediates can be clearly characterized. The model employs
Go-like interactions to stabilize two (or more) experimentally-determined
structures. The approach is trivially parallelizable and readily generalizes to
more complex potentials at minimal cost.

categories: physics.bio-ph physics.chem-ph physics.comp-ph q-bio


title: Greek and Indian Cosmology: Review of Early History

abstract:
  The early Greek and Indian cosmologies are summarized in this paper. The two
traditions appear to have developed independently although after the time of
Alexander they were consciously aware of each other. The focus and style of the
two sciences was different owing to their different cosmologies. Perhaps the
only science which worked more or less the same way in the two civilizations
was medicine. But even here there was important difference. The reason why the
two sciences went their own way in spite of the knowledge of the other was
because their worldviews were different. Indian astronomers, for example, never
paid any attention to Ptolemy's model with its crystalline spheres that looked
restrictive compared to the vast scale of their own conception. On the other
hand, the use of enormous time scales of Indian astronomy must have appeared
unnecessary to the Greeks.


title: Reference Phase of Fresnel Zone Plates

abstract:
  The standard zone plate assumes that the shortest ray connecting a radiation
source and a detection point has a phase of 0 deg thereby defining a reference
phase. Here we examine the experimental consequences of varying this reference
phase from 0 deg to 360 deg. It is concluded that reference phase is an
intrinsic and useful property of zone plates.


title:
Experimental Lagrangian Acceleration Probability Density Function
  Measurement

abstract:
  We report experimental results on the acceleration component probability
distribution function at $R_\lambda = 690$ to probabilities of less than
$10^{-7}$. This is an improvement of more than an order of magnitude over past
measurements and allows us to conclude that the fourth moment converges and the
flatness is approximately 55. We compare our probability distribution to those
predicted by several models inspired by non-extensive statistical mechanics. We
also look at acceleration component probability distributions conditioned on a
velocity component for conditioning velocities as high as 3 times the standard
deviation and find them to be highly non-Gaussian.


title: Unfortunate Terminology

abstract:
  The phrase "negative squared rest mass" can sometimes be found in papers on
neutrinos and frequently occurs in the tachyonic literature. Consequently, some
authors say that "the rest mass of tachyons is imaginary". Besides, the
statement "photons have zero rest mass" is almost common. In terms of
relativity, however, the state of rest cannot be reasonably defined for luxons
and tachyons, and, therefore, today it does not make sense to speak of rest
mass of such objects. It is shown here that the phrases "negative squared
mass", "imaginary mass", and "photon's zero mass" result from applying
bradyonic dynamical relativistic relations to determine properties of luxons
and tachyons; and that this erroneous procedure results from an unfortunate
interpretation of kinematical relativistic relations. It is also shown that the
use of proper relativistic relations, i.e. luxonic or tachyonic ones, gives a
positive quantity having the squared mass dimension. Thus we obtain a nonzero
real quantity having the mass dimension (called masslike quantity), which is
positive for the photon and may (by intuition - should) be positive for other
luxons and for tachyons.


title:
Physical Science: A revitalization of the traditional course by avatars
  of Hollywood in the physics classroom

abstract:
  National studies conducted over many years show that, while most Americans
are interested in science and support federal funding of scientific research,
the scientific literacy of the public is very low. Why this situation exists
and who is responsible are not easy questions to answer. This paper describes a
project aimed at addressing that problem, at least among college students, by
re-designing the general education physical science course, common in most
colleges and universities, to teach basic physics principles via the physics
found in films, particularly the action films popular among today's students.
Results of the first year's trial of the `Physics in Films' approach are more
than promising, they may be pointing the way to the solution of the problem.


title:
Calculation of the interspecies s-wave scattering length in an ultracold
  Na-Rb vapor

abstract:
  We report the calculation of the interspecies scattering length for the
sodium-rubidium (Na-Rb) system. We present improved hybrid potentials for the
singlet $X^1\Sigma^+$ and triplet $a^3\Sigma^+$ ground states of the NaRb
molecule, and calculate the singlet and triplet scattering lengths $a_{s}$ and
$a_{t}$ for the isotopomers $^{23}$Na$^{87}$Rb and $^{23}$Na$^{85}$Rb. Using
these values, we assess the prospects for producing a stable two-species
Bose-Einstein condensate in the Na-Rb system.


title:
Prospects for Forbidden-Transition Spectroscopy and Parity Violation
  Measurements using a Beam of Cold Stable or Radioactive Atoms

abstract:
  Laser cooling and trapping offers the possibility of confining a sample of
radioactive atoms in free space. Here, we address the question of how best to
take advantage of cold atom properties to perform the observation of as highly
forbidden a line as the 6S-7S Cs transition for achieving, in the longer term,
Atomic Parity Violation measurements in radioactive alkali isotopes. Another
point at issue is whether one might do better with stable, cold atoms than with
thermal atoms. To compensate for the large drawback of the small number of
atoms available in a trap, one must take advantage of their low velocity. To
lengthen the time of interaction with the excitation laser, we suggest choosing
a geometry where the laser beam exciting the transition is colinear to a slow,
cold atomic beam, either extracted from a trap or prepared by Zeeman slowing.
We also suggest a new observable physical quantity manifesting APV, which
presents several advantages:specificity, efficiency of detection, possibility
of direct calibration by a parity conserving quantity of a similar nature. It
is well adapted to a configuration where the cold atomic beam passes through
two regions of transverse, crossed electric fields, leading both to
differential measurements and to strong reduction of the contributions from the
M_1-Stark interference signals, potential sources of systematics in APV
measurements. Our evaluation of signal to noise ratios shows that with
available techniques, measurements of transition amplitudes, important as
required tests of Atomic Theory should be possible in cesium 133 with a
statistical precision of 1/1000 and probably also in Fr isotopes for production
rates of 10^6 Fr atoms/s.


abstract:
  Interference between the halves of a double-well trap containing a
Bose-Einstein condensate is studied. It is found that when the atoms in the two
wells are initially in the coherent state, the intensity exhibits collapses and
revivals, but it does not for the initial Fock states. Whether the initial
states are in the coherent states or in a Fock states, the fidelity time has
nothing to do with collision. We point out that interference and its fidelity
can be adjusted experimentally by properly preparing the number and initial
states of the system.


title:
Interaction of a rotational motion and an axial flow in small geometries
  for a Couette-Taylor problem

abstract:
  We analyze the stability of a cylindrical Couette flow under the imposition
of a weak axial flow in case of a very short cylinder with a narrow annulus
gap. We consider an incompressible viscous fluid which is contained in the
narrow gap between two concentric short cylinders, where the inner cylinder
rotates with constant angular velocity. The caps of the cylinders have narrow
tubes conically tapering to super narrow slits which allow for an axial flow
along the surface of the inner cylinder. The approximated solution for the
Couette flow for short cylinders was found and used for the stability analysis
instead of the exact but bulky solution. The sensitivity of the Couette flow to
general small perturbations and to the weak axial flow was studied. We
demonstrate that perturbations coming from the axial flow cause the propagation
of dispersive waves in the Taylor-Couette flow. The coexistence of a rotation
and of an axial flow requires to study in addition to the energy and the
angular momentum also the helicity of the flow. The approximated form for the
helicity formula in case of short cylinders was derived. We found that the
axial flow stabilizes the Taylor - Couette flow. The supercritical flow
includes a rich variety of vortical structures including a symmetric pair of
Taylor vortices, an anomalous single vortex and quasi periodic oscillating
vortices. Pattern formation was studied at large for rated ranges of azimuthal
and axial Reynolds numbers. A region where three branches of different states
occur was localized. Numerical simulations in 3D and in axisymmetrical case of
the model flow are presented, which illustrate the instabilities analyzed.


title: The Gap-Tooth Method in Particle Simulations

abstract:
  We explore the gap-tooth method for multiscale modeling of systems
represented by microscopic physics-based simulators, when coarse-grained
evolution equations are not available in closed form. A biased random walk
particle simulation, motivated by the viscous Burgers equation, serves as an
example. We construct macro-to-micro (lifting) and micro-to-macro (restriction)
operators, and drive the coarse time-evolution by particle simulations in
appropriately coupled microdomains (teeth) separated by large spatial gaps. A
macroscopically interpolative mechanism for communication between the teeth at
the particle level is introduced. The results demonstrate the feasibility of a
closure-on-demand approach to solving hydrodynamics problems.


title: How many clusters? An information theoretic perspective

abstract:
  Clustering provides a common means of identifying structure in complex data,
and there is renewed interest in clustering as a tool for the analysis of large
data sets in many fields. A natural question is how many clusters are
appropriate for the description of a given system. Traditional approaches to
this problem are based either on a framework in which clusters of a particular
shape are assumed as a model of the system or on a two-step procedure in which
a clustering criterion determines the optimal assignments for a given number of
clusters and a separate criterion measures the goodness of the classification
to determine the number of clusters. In a statistical mechanics approach,
clustering can be seen as a trade--off between energy-- and entropy--like
terms, with lower temperature driving the proliferation of clusters to provide
a more detailed description of the data. For finite data sets, we expect that
there is a limit to the meaningful structure that can be resolved and therefore
a minimum temperature beyond which we will capture sampling noise. This
suggests that correcting the clustering criterion for the bias which arises due
to sampling errors will allow us to find a clustering solution at a temperature
which is optimal in the sense that we capture maximal meaningful structure --
without having to define an external criterion for the goodness or stability of
the clustering. We show that, in a general information theoretic framework, the
finite size of a data set determines an optimal temperature, and we introduce a
method for finding the maximal number of clusters which can be resolved from
the data in the hard clustering limit.


title: On an Intriguing Signature-Reversal Exhibited by Cremonian Spacetimes

abstract:
  It is shown that a generic quadro-quartic Cremonian spacetime, which is
endowed with one spatial and three time dimensions, can continuously evolve
into a signature-reversed configuration, i.e. into the classical spacetime
featuring one temporal and three space dimensions. An interesting cosmological
implication of this finding is mentioned.


title: Extreme Outages due to Polarization Mode Dispersion

abstract:
  We investigate the dependence of the bit-error-rate (BER) caused by amplifier
noise in a linear optical fiber telecommunication system on the fiber
birefringence. We show that the probability distribution function (PDF) of BER
obtained by averaging over many realizations of birefringent disorder has an
extended tail corresponding to anomalously large values of BER. We specifically
discuss the dependence of the tail on such details of the pulse detection at
the fiber output as "setting the clock" and filtering procedures.


title:
Compensation for Extreme Outages caused by Polarization Mode Dispersion
  and Amplifier noise

abstract:
  Joint effect of weak birefringent disorder and amplifier noise on
transmission in optical fiber communication systems appears to be strong. The
probability of an extreme outage that corresponds to anomalously large values
of Bit Error Rate (BER) is perceptible. We analyze the dependence of the
Probability Distribution Function (PDF) of BER on the first-order and also
higher-order PMD compensation schemes.


title:
Periodic and Quasi-Periodic Compensation Strategies of Extreme Outages
  caused by Polarization Mode Dispersion and Amplifier Noise

abstract:
  Effect of birefringent disorder on the Bit Error Rate (BER) in an optical
fiber telecommunication system subject to amplifier noise may lead to extreme
outages, related to anomalously large values of BER. We analyze the Probability
Distribution Function (PDF) of BER for various strategies of Polarization Mode
Dispersion (PMD) compensation. A compensation method is proposed that is
capable of more efficient extreme outages suppression, which leads to
substantial improvement of the fiber system performance.


title: Entropy Production of Brownian Macromolecules with Inertia

abstract:
  We investigate the nonequilibrium steady-state thermodynamics of single
Brownian macromolecules with inertia under feedback control in isothermal
ambient fluid. With the control being represented by a velocity-dependent
external force, we find such open systems can have a negative entropy
production rate and we develop a mesoscopic theory consistent with the second
law. We propose an equilibrium condition and define a class of external forces,
which includes a transverse Lorentz force, leading to equilibrium.


title: Logic and thermodynamics: the heat-engine axiomatics of the second law

abstract:
  We challenge the statement that the principle of Thomson and the principle of
Clausius are equivalent. A logical mistake in the supposed textbook proof of
their equivalency is indicated. On this account we refine the heat-engine
axiomatics. We consider the energy exchange in the configuration comprised of
two heat reservoirs and one mechanical device and show explicitly the domains
banned by the laws of thermodynamics.


title: The gas equation for stream

abstract:
  The equation of state for gas stream as analog of well-known equation of
state of gas medium in the static conditions is submitted. The connection of
parameters of state and motion, and also the volume-flow rate and the mass-flow
rate of the gas stream during change of its temperature and pressure as the
result of external action is shown on example of modification of the
represented equation.


title: Quarks in Nuclei

abstract:
  It is generally believed that quarks being confined inside nucleons should
make their presence felt explictly in nuclei only at higher energies. However
it is shown here that the hole in the centre of $ ^{3}H $, $ ^{3}He $ and $
^{4}He $, the neutron halos in nuclei, the $ \alpha - $ and other clustering
effects in nuclei and the nuclear molecules all basically arise due to the same
underlying quark effects. Also the role of triton clustering in very neutron
rich nuclei is emphasized. These require the concept of hidden colour states
which arise from the confinement ideas of QCD for the multi-quark systems.


title:
Lattice Boltzmann Study of Velocity Behaviour in Binary Mixtures Under
  Shear

abstract:
  We apply lattice Boltzmann methods to study the relaxation of the velocity
profile in binary fluids under shear during spinodal decomposition. In simple
fluids, when a shear flow is applied on the boundaries of the system, the time
required to obtain a triangular profile is inversely proportional to the
viscosity and proportional to the square of the size of the system. We find
that the same behaviour also occurs for binary mixtures, for any component
ratio in the mixture and independently from the time when shear flow is
switched on during phase separation.


title: Width-amplitude relation of Bernstein-Greene-Kruskal solitary waves

abstract:
  Inequality width-amplitude relations for three-dimensional
Bernstein-Greene-Kruskal solitary waves are derived for magnetized plasmas.
Criteria for neglecting effects of nonzero cyclotron radius are obtained. We
emphasize that the form of the solitary potential is not tightly constrained,
and the amplitude and widths of the potential are constrained by inequalities.
The existence of a continuous range of allowed sizes and shapes for these waves
makes them easily accessible. We propose that these solitary waves can be
spontaneously generated in turbulence or thermal fluctuations. We expect that
the high excitation probability of these waves should alter the bulk properties
of the plasma medium such as electrical resistivity and thermal conductivity.


title:
Chaos and the continuum limit in nonneutral plasmas and charged particle
  beams

abstract:
  This paper examines discreteness effects in nearly collisionless N-body
systems of charged particles interacting via an unscreened r^-2 force, allowing
for bulk potentials admitting both regular and chaotic orbits. Both for
ensembles and individual orbits, as N increases there is a smooth convergence
towards a continuum limit. Discreteness effects are well modeled by Gaussian
white noise with relaxation time t_R = const * (N/log L)t_D, with L the Coulomb
logarithm and t_D the dynamical time scale. Discreteness effects accelerate
emittance growth for initially localised clumps. However, even allowing for
discreteness effects one can distinguish between orbits which, in the continuum
limit, feel a regular potential, so that emittance grows as a power law in
time, and chaotic orbits, where emittance grows exponentially. For sufficiently
large N, one can distinguish two different `kinds' of chaos. Short range
microchaos, associated with close encounters between charges, is a generic
feature, yielding large positive Lyapunov exponents X_N which do not decrease
with increasing N even if the bulk potential is integrable. Alternatively,
there is the possibility of larger scale macrochaos, characterised by smaller
Lyapunov exponents X_S, which is present only if the bulk potential is chaotic.
Conventional computations of Lyapunov exponents probe X_N, leading to the
oxymoronic conclusion that N-body orbits which look nearly regular and have
sharply peaked Fourier spectra are `very chaotic.' However, the `range' of the
microchaos, set by the typical interparticle spacing, decreases as N increases,
so that, for large N, this microchaos, albeit very strong, is largely
irrelevant macroscopically. A more careful numerical analysis allows one to
estimate both X_N and X_S.

categories: physics.acc-ph astro-ph nlin.CD physics.plasm-ph


title:
A clock transition for a future optical frequency standard with trapped
  atoms

abstract:
  We report the first direct excitation of the strongly forbidden 5s2 1S0-5s5p
3P0 transition in 87Sr. Its frequency is 429 228 004 235 (20) kHz. A resonant
laser creates a small leak in a magneto-optical trap (MOT): atoms build up to
the metastable 3P0 state and escape the trapping process, leading to a
detectable decrease in the MOT fluorescence. This line has a natural width of
10^{-3} Hz and can be used for a new generation of optical frequency standards
using atoms trapped in a light shift free dipole trap.


title: The Active Traveling Wave in the Cochlea

abstract:
  A sound stimulus entering the inner ear excites a deformation of the basilar
membrane which travels along the cochlea towards the apex. It is well
established that this wave-like disturbance is amplified by an active system.
Recently, it has been proposed that the active system consists of a set of
self-tuned critical oscillators which automatically operate at an oscillatory
instability. Here, we show how the concepts of a traveling wave and of
self-tuned critical oscillators can be combined to describe the nonlinear wave
in the cochlea.


title: The Fundamental Principles of Existence and the Origin of Physical Laws

abstract:
  In this essay the ontological structure of reality is explored. The question
of reducibility of biology to physics is considered in the context of their
ultimate principles. It is shown that biology is an ontologically autonomous
science and is based on its own, independent ultimate principle that is
independent from that of physics. In the next step it is shown that
self-consciousness represents a separate realm with its own, ontologically
autonomous, ultimate principle. Understanding that reality is based on ultimate
principles, a new possibility arises to interpret the origin of physical laws.


title: Non-existence of normal tokamak equilibria with negative central current

abstract:
  Recent tokamak experiments employing off-axis, non-inductive current drive
have found that a large central current hole can be produced. The current
density is measured to be approximately zero in this region, though in
principle there was sufficient current drive power for the central current
density to have gone significantly negative. Recent papers have used a large
aspect-ratio expansion to show that normal MHD equilibria (with axisymmetric
nested flux surfaces, non-singular fields, and monotonic peaked pressure
profiles) can not exist with negative central current. We extend that proof
here to arbitrary aspect ratio, using a variant of the virial theorem to derive
a relatively simple integral constraint on the equilibrium. However, this
constraint does not, by itself, exclude equilibria with non-nested flux
surfaces, or equilibria with singular fields and/or hollow pressure profiles
that may be spontaneously generated.


title: Redundancies in Large-scale Protein Interaction Networks

abstract:
  Understanding functional associations among genes discovered in sequencing
projects is a key issue in post-genomic biology. However, reliable
interpretation of the protein interaction data has been difficult. In this
work, we show that if two proteins share significantly larger number of common
interaction partners than random, they have close functional associations.
Analysis of publicly available data from Saccharomyces cerevisiae reveals more
than 2800 reliable functional associations, 29% of which involve at least one
unannotated protein. By further analyzing these associations, we derive
tentative functions for 81 unannotated proteins with high certainty.

categories: physics.bio-ph cond-mat.soft cond-mat.stat-mech physics.data-an q-bio.MN


title: 2000-2003 Real Estate Bubble in the UK but not in the USA

abstract:
  In the aftermath of the burst of the ``new economy'' bubble in 2000, the
Federal Reserve aggressively reduced short-term rates yields in less than two
years from 6.5% to 1.25% in an attempt to coax forth a stronger recovery of the
US economy. But, there is growing apprehension that this is creating a new
bubble in real estate, as strong housing demand is fuelled by historically low
mortgage rates. Are we going from Charybdis to Scylla? This question is all the
more excruciating at a time when many other indicators suggest a significant
deflationary risk. Using economic data, Federal Reserve Chairman A. Greenspan
and Governor D.L. Kohn dismissed recently this possibility. Using the theory of
critical phenomena resulting from positive feedbacks in markets, we confirm
this view point for the US but find that mayhem may be in store for the UK: we
unearth the unmistakable signatures (log-periodicity and power law
super-exponential acceleration) of a strong unsustainable bubble there, which
could burst before the end of the year 2003.

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


title:
Binding energy of the ^3He^4He_2 trimer within the hard-core Faddeev
  approach

abstract:
  We apply a hard-core version of the Faddeev differential equations to the
^3He^4He_2 three-atomic system. Using these equations we calculate the binding
energy of the ^3He^4He_2 trimer with the LM2M2 potential by Aziz and Slaman and
more recent TTY potential by Tang, Toennies and Yiu.


title:
Characteristics of bound modes in coupled dielectric waveguides
  containing negative index media

abstract:
  We investigate the characteristics of guided wave modes in planar coupled
waveguides. In particular, we calculate the dispersion relations for TM modes
in which one or both of the guiding layers consists of negative index media
(NIM)-where the permittivity and permeability are both negative. We find that
the Poynting vector within the NIM waveguide axis can change sign and
magnitude, a feature that is reflected in the dispersion curves.


title: Scaling predictions for radii of weakly bound triatomic molecules

abstract:
  The mean-square radii of the molecules $^4$He$_3$, $^4$He$_2-^6$Li,
$^4$He$_2-^7$Li and $^4$He$_2-^{23}$Na are calculated using a three-body model
with contact interactions. They are obtained from a universal scaling function
calculated within a renormalized scheme for three particles interacting through
pairwise Dirac-delta interaction. The root-mean-square distance between two
atoms of mass $m_A$ in a triatomic molecule are estimated to be of de order of
${\cal C}\sqrt{\hbar^2/[m_A(E_3-E_2)]}$, where $E_2$ is the dimer and $E_3$ the
trimer binding energies, and ${\cal C}$ is a constant (varying from $\sim 0.6$
to $\sim 1$) that depends on the ratio between $E_2$ and $E_3$. Considering
previous estimates for the trimer energies, we also predict the sizes of
Rubidium and Sodium trimers in atomic traps.


title: Recoil-free spectroscopy of neutral Sr atoms in the Lamb-Dicke regime

abstract:
  We have demonstrated a recoil-free spectroscopy on the ${}^1S_0-{}^3P_1$
transition of strontium atoms confined in a one-dimensional optical lattice. By
investigating the wavelength and polarization dependence of the ac Stark shift
acting on the ${}^1S_0$ and ${}^3P_1(m_J=0)$ states, we determined the {\it
magic wavelength} where the Stark shifts for both states coincide. The
Lamb-Dicke confinement provided by this Stark-free optical lattice enabled the
measurement of the atomic spectrum free from Doppler as well as recoil shifts.


title: Louis De Broglie's experiment

abstract:
  Louis de Broglie's celebrated hypothesis transfers a problem of
representation of optics to the quantum theories. Let us suppose that the fact
that originated the problem in optics is the following, "The images obtained by
optical instruments are limited by diffraction. Is the diffraction phenomenon
exclusively restricting of the information contained in the image or does it
have some physical meaning by itself?" This considered as a problem of
measurement of the radiative field does not pose the question of tracing
well-defined processes in the sense of the light quantum concept. Despite this
the application thereto of quantum formalism makes the essentially inferring
statistical nature of measurement forecasting most important. We suggest
avoiding the probabilistic conception of measurement by replacing the
wave-corpuscle dualistic principle with the duality one. The latter is a basic
feature of projective geometry. Referring to it we shall try to include the
diffraction in a geometrical model of optics and interpret in that coherent
schema the point -plane "wave" dual solution. We show what experimental
substantiation the proposed duality has. Lastly, we again discuss the
experimental basis of wave-corpuscle dualism.


title: Elementary Particles as Solutions of a 4-Dimensional Source Equation

abstract:
  The author discusses particular solutions of a second order equation
designated by source equation. This equation is special because the metric of
the space where it is written is influenced by the solution, rendering the
equation recursive. The recursion mechanism is established via a first order
equation which bears some resemblance to Dirac equation. In this paper the
author limits the discussion to solutions with constant norm but makes use of
4-dimensional hypercomplex numbers in matrix representation, a concept that is
formally introduced in a section devoted to that aspect. The particular
solutions that are found exhibit symmetries that can be assigned to spin,
electric and color charges of elementary particles, leaving mass as a free
parameter. Massless particles can also be assigned to special solutions of the
source equation, with the cases of photons, gluons and gravitons clearly
identified, together with another massless particle which does not seem to be
related to anything detected experimentally. Another section deals with
particle dynamics under fields, showing that both gravitational and
electrodynamics can be modelled by geodesics of the spaces whose metric tensors
result from the recursion mechanism. Finally the author suggests two lines of
future work, one deriving fields from densities and currents of masses and
charges and the other one aimed at determining particles' masses.


title: On Einsteinian orbits of celestial bodies

abstract:
  It can be demonstrated that no motion of masses can generate gravitational
waves. Accordingly: i) the time decrease of the orbital period of the famous
binary PSR1913+16 cannot yield an experimental proof of the emission of
gravitational waves; ii) measurements of the propagation of the quasar
J0842+1835 radio-signals past Jupiter cannot reveal the propagation of
gravitational waves sent forth by the planet in its motion around the Sun:
indeed, this motion does not generate any gravitational radiation; iii) the
binary RX J0806.3+1527 has the shortest known revolution period (only 321 s):
however, it cannot be a candidate for the detection of gravitational waves
because no kind of motion of a mass can give origin to a gravitational wave.


title:
An Approximate Expression for the Large Angle Period of a Simple
  Pendulum

abstract:
  A heuristic but pedagogical derivation is given of an explicit formula which
accurately reproduces the period of a simple pendulum even for large
amplitudes. The formula is compared with others in the literature.


title: Characterizing the reflectance of periodic layered media

abstract:
  It has recently been shown that periodic layered media can reflect strongly
for all incident angles and polarizations in a given frequency range. The
standard treatment gets these band gaps from an eigenvalue equation for the
Bloch factor in an infinite periodic structure. We argue that such a procedure
may become meaningless when dealing with structures with not very many periods.
We propose an alternative approach based on a factorization of the multilayer
transfer matrix in terms of three fundamental matrices of simple
interpretation. We show that the trace of the transfer matrix sorts the
periodic structures into three types with properties closely related to one
(and only one) of the three fundamental matrices. We present the reflectance
associated to each one of these types, which can be considered as universal
features of the reflection in these media.


title:
Motion of an Adhesive Gel in a Swelling Gradient: a Mechanism for Cell
  Locomotion

abstract:
  Motivated by the motion of nematode sperm cells, we present a model for the
motion of an adhesive gel on a solid substrate. The gel polymerizes at the
leading edge and depolymerizes at the rear. The motion results from a
competition between a self-generated swelling gradient and the adhesion on the
substrate. The resulting stress provokes the rupture of the adhesion points and
allows for the motion. The model predicts an unusual force-velocity relation
which depends in significant ways on the point of application of the force.


title:
Statistical Yield Modeling for IC Manufacture: Hierarchical Fault
  Distributions

abstract:
  A hierarchical approach to the construction of compound distributions for
process-induced faults in IC manufacture is proposed. Within this framework,
the negative binomial distribution and the compound binomial distribution are
treated as level-1 models. The hierarchical approach to fault distribution
offers an integrated picture of how fault density varies from region to region
within a wafer, from wafer to wafer within a batch, and so on. A theory of
compound-distribution hierarchies is developed by means of generating
functions. With respect to applications, hierarchies of yield means and yield
probability-density functions are considered and an in-process measure of yield
loss is introduced. It is shown that the hierarchical approach naturally
embraces the Bayesian approach.


title:
Pressure Dependence of Energetic (160 keV) Focused Electron Beams
  Arising From Heated or Cooled (LiNbO3) Pyroelectric Crystals

abstract:
  A new effect, gas amplification of electron energy is reported here; namely
when a cylindrical pyroelectric crystal such as (LiNbO3) is contained in a
concentric cylindrical chamber and is heated and then allowed to cool in a
dilute gas the maximum energy of the resultant focused electron beam more than
doubles as the pressure increases from 0.05 to 4 mTorr for seven different
gases.


title: Non-linear and scale-invariant analysis of the Heart Rate Variability

abstract:
  Human heart rate fluctuates in a complex and non-stationary manner.
Elaborating efficient and adequate tools for the analysis of such signals has
been a great challenge for the researchers during last decades. Here, an
overview of the main research results in this field is given. The following
question are addressed: (a) what are the intrinsic features of the heart rate
variability signal; (b) what are the most promising non-linear measures,
bearing in mind clinical diagnostic and prognostic applications.


title: Two-Photon Doppler cooling of alkaline-earth-metal and ytterbium atoms

abstract:
  A new possibility of laser cooling of alkaline-earth-metal and Ytterbium
atoms using a two-photon transition is analyzed. We consider a $^{1}S_{0}$ -
$^{1}S_{0}$ transition, with excitation in near resonance with the $^{1}P_{1}$
level. This greatly increases the two-photon transition rate, allowing an
effective transfer of momentum. The experimental implementation of this
technique is discussed and we show that for Calcium, for example, two-photon
cooling can be used to achieve a Doppler limit of 123 microKelvin. The
efficiency of this cooling scheme and the main loss mechanisms are analyzed.


title:
Geometric phase due to helicity inversion of photons inside an optical
  fiber composed periodically of left- and right- handed media

abstract:
  In this Letter, it is claimed that, in addition to the Chiao-Wu geometric
phase and optical Aharonov-Carmi geometric phase, there exists a new
interesting geometric phase caused by the helicity inversion of photons in the
optical fiber composed periodically of left- and right- handed (LRH) media. By
making use of the Lewis-Riesenfeld invariant theory and the invariant-related
unitary transformation formulation, we calculate this geometric phase. It is
emphasized that this geometric phase should not been neglected when considering
the anomalous refraction on the interfaces between left- and right- handed
media.


title:
Acoustic radiation force and streaming induced by non-periodic
  ultrasound

abstract:
  Starting from the linear flow of homogeneous fluid, five modes are defined as
eigenvectors of the basic system of conservation laws.
  Quasi-plane geometry is considered. Projectors that separate overall
perturbation of the fluid into specific modes are calculated and applied to
nonlinear flow. Dynamic equations for the interacting modes are obtained in the
frames of the method. A particular case of streaming caused by acoustic pulse
is considered, illustrations on temporal behavior of streaming velocity and
streamlines are presented.


title: Degeneracy in the genetic code and its symmetries by base substitutions

abstract:
  Why is the genetic code the way it is? The most successful theory states that
the codon assignments minimise the effects of errors arising in primordial
living systems. Here a transversion is reported that leaves invariant
degeneracy in the genetic code. A model was established to address the
question: How should sets of synonymous codons be chosen to minimise the
deleterious effects of non synonymous substitutions? It is shown that the
arithmetic theory of quadratic forms provides the framework for degeneracy in
the genetic code.


title:
Optical Resonances in Reflectivity near Crystal Modes with Spatial
  Dispersion

abstract:
  We study the effect of spatial dispersion of crystal modes on optical
properties such as the reflectivity $R$. As an example for isotropic media, we
investigate the simplest model for phonons in ionic crystals and compare with
previous results for highly anisotropic plasmons, which are now understood from
a more general point of view. As a consequence of the wave vector dependence of
the dielectric function small changes in the lineshape are predicted. Beyond
that, if the frequency of minimal $R$ is near a pole of the dispersionless
dielectric function, the relative amplitude of dips in $R$ with normal and
anomalous dispersion differ significantly, if dissipation and disorder are low.


title:
Coherent Acceleration of Magnetized Ions by Electrostatic Waves with
  Arbitrary Wavenumbers

abstract:
  This paper studies the coherent acceleration of ions interacting with two
electrostatic waves in a uniform magnetic field B0. This is a generalization of
an earlier analysis of waves propagating perpendicularly to B0 to include the
effect of wavenumbers along B0. The Lie transformation technique is used to
develop a perturbation theory describing the ion motion, and results are
compared with numerical solutions of the complete equations of motion. Coherent
energization occurs when the Doppler-shifted wave frequencies differ by nearly
an integer multiple of the ion cyclotron frequency. When the difference in the
parallel wavenumbers of the two waves is increased the coherent energization of
ions is limited to a small part of the phase space. The energization of ions
and its dependence on wave parameters is discussed.


title:
Accurate relativistic many-body calculations of van der Waals
  coefficients C_8 and C_10 for alkali-metal dimers

abstract:
  We consider long-range interactions between two alkali-metal atoms in their
respective ground states. We extend the previous relativistic many-body
calculations of C_6 dispersion coefficients [Phys.Rev. Lett. {\bf 82}, 3589
(1999)] to higher-multipole coefficients C_8 and C_10. A special attention is
paid to usually omitted contribution of core-excited states. We calculate this
contribution within relativistic random-phase approximation and demonstrate
that for heavy atoms core excitations contribute as much as 10% to the
dispersion coefficients. We tabulate results for both homonuclear and
heteronuclear dimers and estimate theoretical uncertainties. The estimated
uncertainties for C_8 coefficients range from 0.5% for Li_2 to 4% for Cs_2.


title: Investigations of porous radiation dielectric detectors

abstract:
  Multiwire and microstrip porous detectors have been developed and
investigated for DC operation. The multiwire porous detector consists of anode
wires, an Al cathode and a gap between them filled with porous CsI. The
microstrip porous detector consists of an insulating plate covered with
metallic strips, micromesh cathode and a gap between them filled with porous
CsI. For some time after being manufactured, these detectors' performances are
non-stable and they have poor spatial resolution. However, after being kept in
vacuum for a certain time, they spontaneously acquire stability and spatial
resolution better than 100$\mu$m and have detection efficiencies of 100% and
70% for heavily ionizing $\alpha$-particles and 5.9 keV X-rays respectively.
The MWPDD performs stably at an intensity of heavily ionizing $\alpha$
-particles of 711cm$^{-2}$s$^{-1}$.


title: Does tumor growth follow a 'universal law'?

abstract:
  A general model for the ontogenetic growth of living organisms has been
recently proposed. Here we investigate the extension of this model to the
growth of solid malignant tumors. A variety of in vitro and in vivo data are
analyzed and compared with the prediction of a 'universal' law, relating
properly rescaled tumor masses and tumor growth times. The results support the
notion that tumor growth follows such a universal law. Several important
implications of this finding are discussed, including its relevance for tumor
metastasis and recurrence, cell turnover rates, angiogenesis and invasion.


title: Guiding and reflecting light by boundary material

abstract:
  We study effects of finite height and surrounding material on photonic
crystal slabs of one- and two-dimensional photonic crystals with a
pseudo-spectral method and finite difference time domain simulation methods.
The band gap is shown to be strongly modified by the boundary material. As an
application we suggest reflection and guiding of light by patterning the
material on top/below the slab.


title: Plasma formation from ultracold Rydberg gases

abstract:
  Recent experiments have demonstrated the spontaneous evolution of a gas of
ultracold Rydberg atoms into an expanding ultracold plasma, as well as the
reverse process of plasma recombination into highly excited atomic states.
Treating the evolution of the plasma on the basis of kinetic equations, while
ionization/excitation and recombination are incorporated using rate equations,
we have investigated theoretically the Rydberg-to-plasma transition. Including
the influence of spatial correlations on the plasma dynamics in an approximate
way we find that ionic correlations change the results only quantitatively but
not qualitatively.


title:
A maximum principle for the mutation-selection equilibrium of nucleotide
  sequences

abstract:
  We study the equilibrium behaviour of a deterministic four-state
mutation-selection model as a model for the evolution of a population of
nucleotide sequences in sequence space. The mutation model is the Kimura 3ST
mutation scheme, and the selection scheme is assumed to be invariant under
permutation of sites. Considering the evolution process both forward and
backward in time, we use the ancestral distribution as the stationary state of
the backward process to derive an expression for the mutational loss (as the
difference between ancestral and population mean fitness), and we prove a
maximum principle that determines the population mean fitness in
mutation-selection balance.


title:
Quasiclassical double photoionization from the 2^{1,3}S excited states
  of helium including shakeoff

abstract:
  We account for the different symmetries of the 2^{1,3}S helium excited states
in a quasiclassical description of the knockout mechanism augmented by a
quantum shakeoff contribution. We are thus able to formulate the separate
contribution of the knockout and shakeoff mechanisms for double photoionization
for any excess energy from the 2^{1,3}S states. Photoionization ratios and
singly differential cross sections calculated for the 2^{1,3}S excited states
of helium are found to be in very good agreement with recent theoretical
results.


title: Desensitization of a balance with Langmuir binding of weights

abstract:
  A balance is described with Langmuir binding of weights to each side. This
simple physical system, when coupled with a previously derived equation for the
equivalent displacement of weight that perturbs the equilibrium of a balance,
models two-state, receptor systems in pharmacology for receptor activation.
Surprisingly, this system also shows desensitization similar to many
drug-receptor systems. Although understanding the biophysics behind receptor
signaling is an important endeavor by itself, this analogy with a simple
balance may bring new insights into other areas of physics as well.


title:
Interchannel coupling effects in the spin polarization of energetic
  photoelectrons

abstract:
  Effects of the interchannel coupling on the spin polarization of energetic
photoelectrons emitted from atomic Ne valence subshells are examined. Like
previously obtained results for cross sections and angular distributions, the
photoelectron spin polarization parameters too are found considerably
influenced by the coupling. The result completes a series of studies to finally
conclude that the independent particle description is inadequate for the {\em
entire} range of photoionization dynamics over the {\em full} spectral energy
domain


title:
Modeling extracellular field potentials and the frequency-filtering
  properties of extracellular space

abstract:
  Extracellular local field potentials (LFP) are usually modeled as arising
from a set of current sources embedded in a homogeneous extracellular medium.
Although this formalism can successfully model several properties of LFPs, it
does not account for their frequency-dependent attenuation with distance, a
property essential to correctly model extracellular spikes. Here we derive
expressions for the extracellular potential that include this
frequency-dependent attenuation. We first show that, if the extracellular
conductivity is non-homogeneous, there is induction of non-homogeneous charge
densities which may result in a low-pass filter. We next derive a simplified
model consisting of a punctual (or spherical) current source with
spherically-symmetric conductivity/permittivity gradients around the source. We
analyze the effect of different radial profiles of conductivity and
permittivity on the frequency-filtering behavior of this model. We show that
this simple model generally displays low-pass filtering behavior, in which fast
electrical events (such as Na$^+$-mediated action potentials) attenuate very
steeply with distance, while slower (K$^+$-mediated) events propagate over
larger distances in extracellular space, in qualitative agreement with
experimental observations. This simple model can be used to obtain
frequency-dependent extracellular field potentials without taking into account
explicitly the complex folding of extracellular space.


title:
Least-squares fitting approach using energy, gradient and Hessian data
  to obtain an accurate quartic force field : Application to H2O and H2CO

abstract:
  In this work we present an attractive least-squares fitting procedure to
obtain a quartic force field by using energy, gradient and Hessian data arising
from electronic wave function calculations on a suitably chosen grid of points.
We use the experimental design to select the grid points : a simplex-sum of Box
and Behnken grid is used for its efficiency and accuracy. We illustrate the
numerical implementation of the method by using energy and gradient data and we
test for H2O and H2CO the B3LYP/cc-pVTZ quartic force field performed from 11
and 44 simplex-sum configurations. Results compared to classical 44 and 168
energy calculations, show excellent agreement.


title:
Pulse height measurements and electron attachment in drift chambers
  operated with Xe,CO2 mixtures

abstract:
  We present pulse height measurements in drift chambers operated with Xe,CO2
gas mixtures. We investigate the attachment of primary electrons on oxygen and
SF6 contaminants in the detection gas. The measurements are compared with
simulations of properties of drifting electrons. We present two methods to
check the gas quality: gas chromatography and Fe55 pulse height measurements
using monitor detectors.


title: Transient of the kinetic spherical model between two temperatures

abstract:
  We solve the dynamic equation for the kinetic spherical model that initially
is in an arbitrary equilibrium state and then is left to evolve in a heat-bath
with another temperature. Flows of the Renormalizational group are determined.


title: Superstatistics in hydrodynamic turbulence

abstract:
  Superstatistics is a `statistics of a statistics' relevant for driven
nonequilibrium systems with fluctuating intensive parameters. It contains
Tsallis statistics as a special case. We show that the probability density
functions of velocity differences and accelerations measured in Eulerian and
Lagrangian turbulence experiments are well reproduced by simple superstatistics
models. We compare fits obtained for log-normal superstatistics and chi-squared
superstatistics (= Tsallis statistics).


title:
Absolute Hydration Free Energies of Ions, Ion-Water Clusters, and
  Quasi-chemical Theory

abstract:
  Experimental studies on ion-water clusters have provided insights into the
microscopic aspects of hydration phenomena. One common view is that extending
those experimental studies to larger cluster sizes would give the single ion
absolute hydration free energies not obtainable by classical thermodynamic
methods. This issue is reanalyzed in the context of recent computations and
molecular theories on ion hydration, particularly considering the hydration of
H$^+$, Li$^+$, Na$^+$, and HO$^-$ ions and thence the hydration of neutral ion
pairs. The hydration free energies of neutral pairs computed here are in good
agreement with experimental results, whereas the calculated absolute hydration
free energies, and the excess chemical potentials, deviate consistently from
some recently tabulated hydration free energies based on ion-water cluster
data. We show how the single ion absolute hydration free energies are not
separated from the potential of the phase in recent analyses of ion-water
cluster data, even in the limit of large cluster sizes. We conclude that naive
calculations on ion-water clusters ought to agree with results obtained from
experimental studies of ion-water clusters because both values include the
contribution, somewhat extraneous to the local environment of the ion, from the
potential of the phase.


title:
Dynamics and Topological Aspects of a Reconstructed Two-Dimensional Foam
  Time Series Using Potts Model on a Pinned Lattice

abstract:
  We discuss a method to reconstruct an approximate two-dimensional foam
structure from an incomplete image using the extended Potts mode with a pinned
lattice we introduced in a previous paper. The initial information consists of
the positions of the vertices only. We locate the centers of the bubbles using
the Euclidean distance-map construction and assign at each vertex position a
continuous pinning field with a potential falling off as $1/r$. We nucleate a
bubble at each center using the extended Potts model and let the structure
evolve under the constraint of scaled target areas until the bubbles contact
each other. The target area constraint and pinning centers prevent further
coarsening. We then turn the area constraint off and let the edges relax to a
minimum energy configuration. The result is a reconstructed structure very
close to the simulation. We repeated this procedure for various stages of the
coarsening of the same simulated foam and investigated the simulation and
reconstruction dynamics, topology and area distribution, finding that they
agree to good accuracy.


title:
Brownian Motion: Theory and Experiment:: A simple Classroom Measurement
  of the Diffusion Coefficient

abstract:
  Brownian motion is the perpetual irregular motion exhibited by small
particles immersed in a fluid. Such random motion of the particles is produced
by statistical fluctuations in the collisions they suffer with the molecules of
the surrounding fluid. Brownian motion of particles in a fluid (like milk
particles in water) can be observed under a microscope. Here we describe a
simple experimental set-up to observe Brownian motion and a method of
determining the diffusion coefficient of the Brownian particles, based on a
theory due to Smoluchowski. While looking through the microscope we focus
attention on a fixed small volume, and record the number of particles that are
trapped in that volume, at regular intervals of time. This gives us a
time-series data, which is enough to determine the diffusion coefficient of the
particles to a good degree of accuracy.


title:
Hydrodynamic equations for incompressible inviscid fluid in terms of
  generalized stream function

abstract:
  Hydrodynamic equations for ideal incompressible fluid are written in terms of
generalized stream function. Two-dimensional version of these equations is
transformed to the form of one dynamic equation for the stream function. This
equation contains arbitrary function which is determined by inflow conditions
given on the boundary. To determine unique solution, velocity and vorticity
(but not only velocity itself) must be given on the boundary. This unexpected
circumstance may be interpreted in the sense that the fluid has more degrees of
freedom, than it was believed. Besides, the vorticity is less observable
quantity as compared with the velocity. It is shown that the Clebsch potentials
are used essentially at the description of vortical flow.


title:
Dynamical analysis of the nonlinear growth of the m=n=1 resistive
  internal mode

abstract:
  A dynamical analysis is presented that self-consistently takes into account
the motion of the critical layer, in which the magnetic field reconnects, to
describe how the m=n=1 resistive internal kink mode develops in the nonlinear
regime. The amplitude threshold marking the onset of strong nonlinearities due
to a balance between convective and mode coupling terms is identified. We
predict quantitatively the early nonlinear growth rate of the m=n=1 mode below
this threshold.

categories: physics.plasm-ph physics.flu-dyn physics.gen-ph physics.geo-ph


title: The power law character of off-site power failures

abstract:
  A study on the behavior of off-site AC power failure recovery times at three
nuclear plant sites is presented. It is shown, that power law is appropriate
for the representation of failure frequency-duration correlation function of
off-site power failure events, based on simple assumptions about component
failure and repair rates. It is also found that the annual maxima of power
failure duration follow Frechet distribution, which is a type II asymptotic
distribution, strengthening our assumption of power law for the parent
distribution. The extreme value distributions obtained are used to extrapolate
for failure durations beyond the observed range.


title: Coulombic Energy Transfer and Triple Ionization in Clusters

abstract:
  Using neon and its dimer as a specific example, it is shown that excited
Auger decay channels that are electronically stable in the isolated monomer can
relax in a cluster by electron emission. The decay mechanism, leading to the
formation of a tricationic cluster, is based on an efficient energy-transfer
process from the excited, dicationic monomer to a neighbor. The decay is
ultrafast and expected to be relevant to numerous physical phenomena involving
core holes in clusters and other forms of spatially extended atomic and
molecular matter.


title: Automatic generation of vacuum amplitude many-body perturbation series

abstract:
  An algorithm and a computer program in Fortran 95 are presented which
enumerate the Hugenholtz diagram representation of the many-body perturbation
series for the ground state energy with a two-body interaction. The output is
in a form suitable for post-processing such as automatic code generation. The
results of a particular application, generation of LaTeX code to draw the
diagrams, is shown.


title: Importance of direct and indirect triggered seismicity

abstract:
  Using the simple ETAS branching model of seismicity, which assumes that each
earthquake can trigger other earthquakes, we quantify the role played by the
cascade of triggered seismicity in controlling the rate of aftershock decay as
well as the overall level of seismicity in the presence of a constant external
seismicity source. We show that, in this model, the fraction of earthquakes in
the population that are aftershocks is equal to the fraction of aftershocks
that are indirectly triggered and is given by the average number of triggered
events per earthquake. Previous observations that a significant fraction of
earthquakes are triggered earthquakes therefore imply that most aftershocks are
indirectly triggered by the mainshock.


title: The laminar flow instability criterion and turbulence in pipe

abstract:
  The identification of stream in the straight pipe as a flexible rod has
allowed to present the criterion expression for determination of transition of
the laminar flow regime to the turbulent as a loss of stability of the
rectilinear static structure of translational motion of stream in pipe and its
transition to the flexural-vortical dynamic structure of translational motion,
just as a flexible rod buckling. The introduced criterion allows to take into
account an influencing of the inlet geometry, the pipe length, the flow
velocity, and also of any physical factors on stability of the rectilinear flow
structure. It is ascertained, that Reynolds number is the number of local
hydrodynamic similarity and it is displayed that one is constituent part of the
introduced stability criterion. The developed approach to a problem of
stability is applicable for a problem solving on internal flow and external
streamline.


title:
Imaging Studies of Characteristics for a Slab of a Lossy Left-handed
  Material

abstract:
  The characteristics of an imaging system formed by a slab of a lossy
left-handed material (LHM) are studied. The transfer function of the LHM
imaging system is written in an appropriate product form with each term having
a clear physical interpretation. A tiny loss of the LHM may suppress the
transmission of evanescent waves through the LHM slab and this is explained
physically. An analytical expression for the resolution of the imaging system
is derived. It is shown that it is impossible to make a subwavelength imaging
by using a realistic LHM imaging system unless the LHM slab is much thinner
than the wavelength.


title: Diffraction to De-Diffraction

abstract:
  De-diffraction (DD), a new procedure to totally cancel diffraction effects
from wave-fields is presented, whereby the full field from an aperture is
utilized and a truncated geometrical field is obtained, allowing infinitely
sharp focusing and non-diverging beams. This is done by reversing a diffracted
wave-fields' direction. The method is derived from the wave equation and
demonstrated in the case of Kirchhoff's integral. An elementary bow-wavelet is
described and the DD process is related to quantum and relativity theories.


title:
Long-Bone Allometry of Terrestrial Mammals and the Geometric-Shape and
  Elastic-Force Constraints of Bone Evolution

abstract:
  A natural similarity in body dimensions of terrestrial animals noticed by
ancient philosophers remains the main key to the problem of mammalian skeletal
evolution with body mass explored in theoretical and experimental biology and
tested by comparative zoologists. We discuss the long-standing problem of
mammalian bone allometry commonly studied in terms of the so-called
''geometric'', ''elastic'', and ''static stress'' similarities by McMahon
(1973, 1975a, 1975b). We revise the fundamental assumptions underlying these
similarities and give new physical insights into geometric-shape and
elastic-force constraints imposed on spatial evolution of mammalian long bones.


title: Are Aftershocks of Large Californian Earthquakes Diffusing?

abstract:
  We analyze 21 aftershock sequences of California to test for evidence of
space-time diffusion. Aftershock diffusion may result from stress diffusion and
is also predicted by any mechanism of stress weakening. Here, we test an
alternative mechanism to explain aftershock diffusion, based on multiple
cascades of triggering. In order to characterize aftershock diffusion, we
develop two methods, one based on a suitable time and space windowing, the
other using a wavelet transform adapted to the removal of background
seismicity. Both methods confirm that diffusion of seismic activity is very
weak, much weaker than reported in previous studies. A possible mechanism
explaining the weakness of observed diffusion is the effect of geometry,
including the localization of aftershocks on a fractal fault network and the
impact of extended rupture lengths which control the typical distances of
interaction between earthquakes.


title:
Ex-nihilo II: Examination Syllabi and the Sequencing of Cosmology
  Education

abstract:
  Cosmology education has become an integral part of modern physics courses.
Directed by National Curricula, major UK examination boards have developed
syllabi that contain explicit statements about the model of the Big Bang and
the strong observational evidence that supports it. This work examines the
similarities and differences in these specifications, addresses when cosmology
could be taught within a physics course, what should be included in this
teaching and in what sequence it should be taught at different levels.


title:
Lyapunov exponents in constrained and unconstrained ordinary
  differential equations

abstract:
  We discuss several numerical methods for calculating Lyapunov exponents (a
quantitative measure of chaos) in systems of ordinary differential equations.
We pay particular attention to constrained systems, and we introduce a variety
of techniques to address the complications introduced by constraints. For all
cases considered, we develop both deviation vector methods, which follow the
time-evolution of the difference between two nearby trajectories, and Jacobian
methods, which use the Jacobian matrix to determine the true local behavior of
the system. We also assess the merits of the various methods, and discuss
assorted subtleties and potential sources of error.


title: In Memory of Julian Schwinger

abstract:
  Although he was the recipient of a Nobel Prize and despite the greatness of
his accomplishments, Julian Schwinger is almost an unsung hero of our age . He
is relatively unknown to the general population, even though in the physics
community he was a renowned theoretician and teacher of physics. He shared the
1965 Nobel Prize in physics with Richard P. Feynman and Shin'ichiro Tomonaga
for their development of Quantum Electrodynamics (QED). Of these three
extraordinary physicists, and even of all the physicists that worked on QED,
his work was the most rigorous and mathematically exacting.


title:
Anisotropic "charge-flipping" acceleration of highly charged ions from
  $(N_2)_n$ clusters in strong optical fields

abstract:
  The disassembly of molecular clusters $(N_2)_n$ ($n$=50-3000) in strong
optical fields is investigated using two-dimensional time-of-flight
spectrometry. Very highly charged ions are formed with a two-component energy
distribution. A low-energy, isotropic component correlates with Coulomb
explosion. A high-energy, anisotropic component, that results from a ``charge
flipping" acceleration mechanism, gives rise to ions with energies in excess of
the Coulombic limit.


title: Explosions of water clusters in intense laser fields

abstract:
  Energetic, highly-charged oxygen ions, $O^{q+}$ ($q\leq 6$), are copiously
produced upon laser field-induced disassembly of highly-charged water clusters,
$(H_2O)_n$ and $(D_2O)_n$, $n\sim$ 60, that are formed by seeding high-pressure
helium or argon with water vapor. $Ar_n$ clusters (n$\sim$40000) formed under
similar experimental conditions are found undergo disassembly in the Coulomb
explosion regime, with the energies of $Ar^{q+}$ ions showing a $q^2$
dependence. Water clusters, which are argued to be considerably smaller in
size, should also disassemble in the same regime, but the energies of fragment
O$^{q+}$ ions are found to depend linearly on $q$ which, according to
prevailing wisdom, ought to be a signature of hydrodynamic expansion that is
expected of much larger clusters. The implication of these observations on our
understanding of the two cluster explosion regimes, Coulomb explosion and
hydrodynamic expansion, is discussed. Our results indicate that charge state
dependences of ion energy do not constitute an unambiguous experimental
signature of cluster explosion regime.


title:
Threshold and high-frequency behavior of dipole-bound anion
  photodetachment

abstract:
  An explicit analytic description is given for dipole-bound anion (DBA) as an
excess electron bound to the molecular neutral due to its dipole moment. The
calculated DBA photodetachment cross-section displays $\propto\omega^{-2}$
behavior for large $\omega$, in complete accordance with the experimental data
[Bailey \textit{et al.}, J. Chem. Phys \textbf{104}, 6976 (1996)]. At the
threshold the photodetachment cross-section displays the Gailitis--Damburg
oscillations.


title: United Dipole Field

abstract:
  The field of an electromagnetic (E) dipole has been examined using general
relativistic (R) and quantum mechanical (Q) points of view, and an E=Q=R
equivalence principle presented whereas the curvature of the electromagnetic
streamlines of the field are taken to be evidence of the distortion of
spacetime, and hence of the presence of a gravitational field surrounding the
dipole. Using a quasi-refractive index function N, with the streamlines and
equipotential surfaces as coordinates, a new dipole relativistic metric is
described, replacing Schwarzschild's for a point mass. The same principle
equates the curvature and other physical features of the field with fundamental
quantum concepts such as the uncertainty principle, the probability
distribution and the wave packet. The equations of the dipole field therefore
yield the three fields emerging naturally one from the other and unified
without resorting to any new dimensions. It is speculated whether this model
can be extended to dipolar matter-antimatter pairs.


title: Spontaneously generated X-shaped light bullets

abstract:
  We observe the formation of an intense optical wavepacket fully localized in
all dimensions, i.e. both longitudinally (in time) and in the transverse plane,
with an extension of a few tens of fsec and microns, respectively. Our
measurements show that the self-trapped wave is a X-shaped light bullet
spontaneously generated from a standard laser wavepacket via the nonlinear
material response (i.e., second-harmonic generation), which extend the soliton
concept to a new realm, where the main hump coexists with conical tails which
reflect the symmetry of linear dispersion relationship.


title:
A two dimensional position sensitive gas chamber with scanned charge
  transfer readout

abstract:
  We have constructed and tested a 2d position sensitive parallel-plate gas
ionization chamber with scanned charge transfer readout. The scan readout
method described here is based on the development of a new position dependent
charge transfer technique. It has been implemented by using gate strips
perpendicularly oriented to the collector strips. This solution reduces
considerably the number of electronic readout channels needed to cover large
detector areas. The use of a 25 micron thick kapton etched circuit allows high
charge transfer efficiency with a low gating voltage, consequently needing a
very simple commutating circuit. The present prototype covers 8 x 8 cm^2 with a
pixel size of 1.27 x 1.27 mm^2. Depending on the intended use and beam
characteristics a smaller effective pixel is feasible and larger active areas
are possible. This detector can be used for X-ray or other continuous beam
intensity profile monitoring.


title: A singular integrable equation from short capillary-gravity waves

abstract:
  From a columnar approximation of the Euler equations of an incompressible
fluid with surface tension, we derive in the short-wave approximation a new
integrable classical 1+1 dimensional field theory for the motion of the
surface. Together with a Lorentz invariance,this system has the novel feature
of solutions which become multiple valued in finite time.


title:
Ray helicity: a geometric invariant for multi-dimensional resonant wave
  conversion

abstract:
  For a multicomponent wave field propagating into a multidimensional
conversion region, the rays are shown to be helical, in general. For a
ray-based quantity to have a fundamental physical meaning it must be invariant
under two groups of transformations: congruence transformations (which shuffle
components of the multi-component wave field) and canonical transformations
(which act on the ray phase space). It is shown that for conversion between two
waves there is a new invariant not previously discussed: the intrinsic helicity
of the ray.


title: Instabilities in the transient response of muscle

abstract:
  We investigate the isometric transient response of muscle using a
quantitative stochastic model of the actomyosin cycle based on the swinging
lever-arm hypothesis. We first consider a single pair of filaments, and show
that when values of parameters such as the lever-arm displacement and the
crossbridge elasticity are chosen to provide effective energy transduction, the
T2 curve (the tension recovered immediately after a step displacement) displays
a region of negative slope. If filament compliance and the discrete nature of
the binding sites are taken into account, the negative slope is diminished, but
not eliminated. This implies that there is an instability in the dynamics of
individual half-sarcomeres. However, when the symmetric nature of whole
sarcomeres is taken into account, filament rearrangement becomes important
during the transient: as tension is recovered, some half-sarcomeres lengthen
while others shorten. This leads to a flat T2 curve, as observed
experimentally. In addition, we investigate the isotonic transient response and
show that for a range of parameter values the model displays damped
oscillations, as recently observed in experiments on single muscle fibers. We
conclude that it is essential to consider the collective dynamics of many
sarcomeres, rather than the dynamics of a single pair of filaments, when
interpreting the transient response of muscle.


title:
Linking Vibrational Dynamics to Local Electronic Structure: Local
  Analysis of Dynamics of the relaxed Si$_{87}$ Cluster

abstract:
  A flexible scheme for decomposing the vibrational density of states in terms
of pair vibrational density of states is presented. This scheme provides the
linkage between the site vibrational density of states and pair vibrational
density of states so that vibrational modes, in particular localized modes, can
be conveniently examined in terms of the correlation between the vibration at a
given site and those at its neighboring sites. Furthermore, within the
framework of a total energy vibrational spectrum study, this scheme allows the
analysis of vibrational modes in terms of their electronic origin. A case study
of the vibrational dynamics of the relaxed Si$_{87}$ cluster is carried out to
demonstrate the flexibility of the scheme in analyzing the properties of
vibrational modes, particularly for complex systems with reduced or no
symmetry.


title: An Estimate of the Vibrational Frequencies of Spherical Virus Particles

abstract:
  The possible normal modes of vibration of a nearly spherical virus particle
are discussed. Two simple models for the particle are treated, a liquid drop
model and an elastic sphere model. Some estimates for the lowest vibrational
frequency are given for each model. It is concluded that this frequency is
likely to be of the order of a few GHz for particles with a radius of the order
of 50 nm.


title: Statistical Properties of Nonlinear Phase Noise

abstract:
  The statistical properties of nonlinear phase noise, often called the
Gordon-Mollenauer effect, is studied analytically when the number of fiber
spans is very large. The joint characteristic functions of the nonlinear phase
noise with electric field, received intensity, and the phase of amplifier noise
are all derived analytically. Based on the joint characteristic function of
nonlinear phase noise with the phase of amplifier noise, the error probability
of signal having nonlinear phase noise is calculated using the Fourier series
expansion of the probability density function. The error probability is
increased due to the dependence between nonlinear phase noise and the phase of
amplifier noise. When the received intensity is used to compensate the
nonlinear phase noise, the optimal linear and nonlinear minimum mean-square
error compensators are derived analytically using the joint characteristic
function of nonlinear phase noise and received intensity. Using the joint
probability density of received amplitude and phase, the optimal maximum a
posteriori probability detector is derived analytically. The nonlinear
compensator always performs better than linear compensator.


title: Is the temperature as a Lorentz scalar?

abstract:
  For the free Fermion gas at thermodynamic equilibrium, the temperature which
represents the averaged kinetic energy is demonstrated to have the proper
property which is invariant under the Lorentz boost, using the conceptions of
the relativistic quantum field theory and statistical physics. The
thermodynamic interaction is described by the coupling of particles with the
vacuum of a scalar pseudo boson which features a self-interaction. The various
measurement of the apparent temperature of a moving body is also investigated.


title:
Data Acquisition Systems and Computing Infrastructure of the IBR-2
  Complex: present and near future

abstract:
  In the period 2003-2009 in the Frank Laboratory of Neutron Physics, JINR, the
total modernization of the IBR-2 pulsed reactor which is mainly used for
investigations in condensed matter physics using thermal neutron scattering
will be carried out (it is planned to replace the movable and stationary
reflectors and reactor jacket, to conduct fuel reloading, to update the
automated system for measurement and control of the reactor parameters, etc).
The main aims of the IBR-2 modernization are to improve the reactor parameters
and to increase the nuclear safety and reliability of the reactor. In the
mentioned period the development of new instruments and modernization of
existing neutron spectrometers are planned as well. In this connection in FLNP
the 7-years program of the development of DAQ system and computing
infrastructure was worked out.The main problems in building new DAQ systems for
neutron spectrometers are reliability, cost, time of development and
commissioning and rapid system adaptation. Adaptability is of key importance
since it gives the flexibility to meet unknown future needs.


title: Exact scattering theory for any straight reflectors in two dimensions

abstract:
  The exact Green function for the scalar wave equation in a plane with any set
of perfectly reflecting straight mirrors, which may be joined to form corners,
is given as a diffraction scattering series. Instances would be slit
diffraction in optics, or the Schrodinger equation inside (or outside) a
general polygonal enclosure ('quantum polygon billiards'). The method is based
on the seminal 1896 Riemann helicoid surface solution by Sommerfeld for optical
diffraction by a single corner. It is generalised to account for multiple
scatter by adapting the analysis of Stovicek for a closely related problem: a
collection of magnetic flux lines (points) in a plane, the multi-flux
Aharonov-Bohm effect. The short wavelength limit is shown to yield the
'geometrical theory of diffraction'. For slit diffraction the exact series is
shown to coincide with that of Schwarzschild in 1902.


title: Superfluid Fermi Gases with Large Scattering Length

abstract:
  We report quantum Monte Carlo calculations of superfluid Fermi gases with
short-range two-body attractive interactions with infinite scattering length.
The energy of such gases is estimated to be $(0.44 \pm 0.01)$ times that of the
noninteracting gas, and their pairing gap is approximately twice the energy per
particle.


title: Relativistic and QED energy shifts in positronium ion

abstract:
  The leading relativistic and QED corrections to the ground state energy of
the three-body system (epe) are calculated numerically using a Hylleraas
correlated basis set. The accuracy of the nonrelativistic variational ground
state wave function is discussed with respect to the convergence properties at
the increase of the basis dimension and to the variance of the energy
expectation value. Recent progress in the numerical procedure used to calculate
expectation values for products of various physical operators is presented. It
is shown that the nonrelativistic ground state energy can be calculated with an
accuracy below the level width. The corrections to this energy include the
lowest order Breit interaction, the vacuum polarization potential, one and two
photon exchange contributions, the annihilation interaction, and spin-spin
contact terms. The relativistic effects and the residual interactions
considered here decrease the one electron binding energy from the
nonrelativistic value of 0.012 005 070 232 980 10(3) a.u. to 0.011 981 051
246(2) a.u..


title: Liquid-vapor oscillations of water in hydrophobic nanopores

abstract:
  Water plays a key role in biological membrane transport. In ion channels and
water-conducting pores (aquaporins), one dimensional confinement in conjunction
with strong surface effects changes the physical behavior of water. In
molecular dynamics simulations of water in short (0.8 nm) hydrophobic pores the
water density in the pore fluctuates on a nanosecond time scale. In long
simulations (460 ns in total) at pore radii ranging from 0.35 nm to 1.0 nm we
quantify the kinetics of oscillations between a liquid-filled and a
vapor-filled pore. This behavior can be explained as capillary evaporation
alternating with capillary condensation, driven by pressure fluctuations in the
water outside the pore. The free energy difference between the two states
depends linearly on the radius. The free energy landscape shows how a
metastable liquid state gradually develops with increasing radius. For radii
larger than ca. 0.55 nm it becomes the globally stable state and the vapor
state vanishes. One dimensional confinement affects the dynamic behavior of the
water molecules and increases the self diffusion by a factor of two to three
compared to bulk water. Permeabilities for the narrow pores are of the same
order of magnitude as for biological water pores. Water flow is not continuous
but occurs in bursts. Our results suggest that simulations aimed at collective
phenomena such as hydrophobic effects may require simulation times longer than
50 ns. For water in confined geometries, it is not possible to extrapolate from
bulk or short time behavior to longer time scales.


title: Electromagnetic energy-momentum and forces in matter

abstract:
  We discuss the electromagnetic energy-momentum distribution and the
mechanical forces of the electromagnetic field in material media. There is a
long-standing controversy on these notions. The Minkowski and the Abraham
energy-momentum tensors are the most well-known ones. We propose a solution of
this problem which appears to be natural and self-consistent from both a
theoretical and an experimental point of view.


title: Constant-Force-Magnitude Chaotic Oscillator

abstract:
  A numerical model is presented for a mechanical oscillator in which the
magnitude of the restoring force is constant. Unlike the harmonic oscillator,
where force is proportional to displacement, this nonlinear system can be
chaotic when externally driven.


title: Control of cardiac alternans in a mapping model with memory

abstract:
  We investigate a map-based model of paced cardiac muscle in the presence of
closed-loop feedback control. The model relates the duration of an action
potential to the preceding diastolic interval as well as the preceding action
potential duration and thus has some amount of `memory.' We find that the
domain of control depends on this memory, independently of the specific
functional form of the map. The memory-dependent domain of control can
encompass large feedback gains, thus providing the first possible explanation
of the recent experimental results of Hall et al. [Phys. Rev. Lett, 88, 198102
(2002)] on controlling alternans in small pieces of rapidly-paced cardiac
muscle.


title:
Impact of Interatomic Electronic Decay Processes on Xe 4d Hole Decay in
  the Xenon Fluorides

abstract:
  A hole in a 4d orbital of atomic xenon relaxes through Auger decay after a
lifetime of 3 fs. Adding electronegative fluorine ligands to form xenon
fluoride molecules, results in withdrawal of valence-electron density from Xe.
Thus, within the one-center picture of Auger decay, a lowered Xe 4d Auger width
would be expected, in contradiction, however, with experiment. Employing
extensive ab initio calculations within the framework of many-body Green's
functions, we determine all available decay channels in XeFn and characterize
these channels by means of a two-hole population analysis. We derive a relation
between two-hole population numbers and partial Auger widths. On this basis,
interatomic electronic decay processes are demonstrated to be so strong in the
xenon fluorides that they overcompensate the reduction in intra-atomic Auger
width and lead to the experimentally observed trend. The nature of the relevant
processes is discussed. These processes presumably underlie Auger decay in a
variety of systems.


title:
Submodels of the Special Compressible Fluid on Two-Dimensional
  Subalgebras

abstract:
  The article take up two-dimensional subalgebras from optimum system of
algebra $L_{13}$, which is deduce from the gas dynamics equations. We
calculated invariants and constructed invariant submodels for two-dimensional
sabalgebras. Then invariant submodels are reduce to one of canonical types:
evolutionary or stationary.


title: Le groupe de Lorentz-Einstein comme consequence d'un quantum d'action

abstract:
  It is shown that the natural quantization of intervals between events (in the
relativistic sense) leads to the definition of two units, c and h, implying the
formulae for the transformation of co-ordinates as well as the fundamental
quantum formulae.
  -----
  On montre comment la quantification naturelle des intervalles entre
evenements (au sens relativiste) conduit a la definition de deux unites, c et
h, entrainant aussi bien les formules de transformation de coordonnees que les
formules quantiques fondamentales.


title: Comment on `About the magnetic field of a finite wire'

abstract:
  A flaw is pointed out in the justification given by Charitat and Graner [2003
Eur. J. Phys. vol. 24, 267] for the use of the Biot--Savart law in the
calculation of the magnetic field due to a straight current-carrying wire of
finite length.


title: The Linear Momentum as a Tensor Function

abstract:
  At present, whenever we work in newtonian mechanics we consider momentum to
be a three-dimensional vector or a 4-dimensional one when we work in
relativistic mechanics. However, this mathematical vector model has barely 200
years and its complete installation in the physics is hardly more than 100
years old. In classical mechanics, based on point particles with mass, momentum
is considered as a vector because the speed of the particle is applied on a
single point and the mass is defined only at that point. When the extension to
classical rigid solids is made, that is, to solids that keep their shape, being
so that the speed is defined to be the same for each and every point where the
solid is defined, then the viewpoint of momentum as a vector is the simplest
and more convenient approach. Relativity (restricted and general) was developed
in the decades of 1900 and 1910 and quantum mechanics in the decades of 1920
and 1930. Relativity then impedes the existence of classical rigid solids. The
maximum speed for the transmission of signals prevents a body from varying its
status without being deformed. On the other hand, quantum physics breaks up
with the concept of point particles with mass, substituting this model for the
one of the wave function defined in an extensive region of the space
(space-time in the quantum relativity). Can we really define, the moment of a
relativistic solid or of a wave function with a simple vector?


title:
Second constant of motion for two-dimensional positronium in a magnetic
  field

abstract:
  Recent numerical work indicates that the classical motion of positronium in a
constant magnetic field does not exhibit chaotic behavior if the system is
confined to two dimensions. One would therefore expect this system to possess a
second constant of the motion in addition to the total energy. In this paper we
construct a generalization of the Laplace-Runge-Lenz vector and show that a
component of this vector is a constant of the motion.


title: Vector constants of the motion and orbits in the Coulomb/Kepler problem

abstract:
  The equation for the conic sections describing the possible orbits in a
potential $V \sim r^{-1}$ is obtained by means of a vector constant of the
motion differing from the traditional Laplace-Runge-Lenz vector.


title:
Close-Coupling Time-Dependent Quantum Dynamics Study of the H + HCl
  Reaction

abstract:
  The paper presents a theoretical study of the dynamics of the H + HCl system
on the potential energy surface (PES) of Bian and Werner (Bian, W.; Werner, H.
-J., J. Chem. Phys. 2000, 112, 220). A time-dependent wave packet approach was
employed to calculate state-to-state reaction probabilities for the exchanged
and abstraction channels. The most recent PES for the system has been used in
the calculations. Reaction probabilities have also been calculated for several
values of the total angular momentum J > 0. Those have then been used to
estimate cross sections and rate constants for both channels. The calculated
cross sections can be compared with the results of previous quasiclassical
trajectory calculations and reaction dynamics experimental on the abstraction
channel. In addition, the calculated rate constants are in the reasonably good
agreement with experimental measurement.


title:
A Gedanken spacecraft that operates using the quantum vacuum (Dynamic
  Casimir effect)

abstract:
  Conventional rockets are not a suitable technology for deep space missions.
Chemical rockets require a very large weight of propellant, travel very slowly
compared to light speed, and require significant energy to maintain operation
over periods of years. For example, the 722 kg Voyager spacecraft required
13,600 kg of propellant to launch and would take about 80,000 years to reach
the nearest star, Proxima Centauri, about 4.3 light years away. There have been
various attempts at developing ideas on which one might base a spacecraft that
would permit deep space travel, such as spacewarps. In this paper we consider
another suggestion from science fiction and explore how the quantum vacuum
might be utilized in the creation of a novel spacecraft. The spacecraft is
based on the dynamic Casimir effect, in which electromagnetic radiation is
emitted when an uncharged mirror is properly accelerated in the vacuum. The
radiative reaction produces a dissipative force on the mirror that tends to
resist the acceleration of the mirror. This force can be used to accelerate a
spacecraft attached to the mirror. We also show that, in principal, one could
obtain the power to operate the accelerated mirror in such a spacecraft using
energy extracted from the quantum vacuum using the standard Casimir effect
witha parallel plate geometry. Unfortunately the method as currently conceived
generates a miniscule thrust, and is no more practical than a spacewarp, yet it
does provide an interesting demonstration of our current understanding of the
physics of the quantized electromagnetic field in vacuum.


title:
Information capacity of optical fiber channels with zero average
  dispersion

abstract:
  We study the statistics of optical data transmission in a noisy nonlinear
fiber channel with a weak dispersion management and zero average dispersion.
Applying path integral methods we have found exactly the probability density
functions of channel output both for a non-linear noisy channel and for a
linear channel with additive and multiplicative noise. We have obtained
analytically a lower bound estimate for the Shannon capacity of considered
nonlinear fiber channel.


title: Particle in a box at high temperature

abstract:
  High temperature expansion of the partition function for a particle on a
segment of a line is found to show an example of the quantum system that
thermodynamical functions do not approach the thermodynamical functions of its
classical counterpart at high temperature. The problem might be interesting for
the students and teachers because by a collection of noninteracting particles
trapped in a box at sufficiently high temperature and low density one imitates
the classical ideal gas.


title: Inference for bounded parameters

abstract:
  The estimation of signal frequency count in the presence of background noise
has had much discussion in the recent physics literature, and Mandelkern [1]
brings the central issues to the statistical community, leading in turn to
extensive discussion by statisticians. The primary focus however in [1] and the
accompanying discussion is on the construction of a confidence interval. We
argue that the likelihood function and $p$-value function provide a
comprehensive presentation of the information available from the model and the
data. This is illustrated for Gaussian and Poisson models with lower bounds for
the mean parameter.


title: A modified SPH approach for fluids with large density differences

abstract:
  We introduce a modified SPH approach that is based on discretising the
particle density instead of the mass density. This approach makes it possible
to use SPH particles with very different masses to simulate multi-phase flows
with large differences in mass density between the phases. We test our
formulation with a simple advection problem, with sound waves encountering a
density discontinuity, and with shock tubes containing a contact discontinuity
between air and Diesel oil. For all examined problems where particles have
different masses, the new formulation yields better results than standard SPH.
This is also the case for problems in which different spatial resolutions are
needed while the mass density does not change.


title:
A Method for Ultrashort Electron Pulse Shape-Measurement Using Coherent
  Synchrotron Radiation

abstract:
  In this paper we discuss a method for nondestructive measurements of the
longitudinal profile of sub-picosecond electron bunches for X-Ray Free Electron
Lasers (XFELs). The method is based on the detection of the Coherent
Synchrotron Radiation (CSR) spectrum produced by a bunch passing a dipole
magnet system. This work also contains a systematic treatment of synchrotron
radiation theory which lies at the basis of CSR. Standard theory of synchrotron
radiation uses several approximations whose applicability limits are often
forgotten: here we present a systematic discussion about these assumptions.
Properties of coherent synchrotron radiation from an electron moving along an
arc of a circle are then derived and discussed. We describe also an effective
and practical diagnostic technique based on the utilization of an
electromagnetic undulator to record the energy of the coherent radiation pulse
into the central cone. This measurement must be repeated many times with
different undulator resonant frequencies in order to reconstruct the modulus of
the bunch form-factor. The retrieval of the bunch profile function from these
data is performed by means of deconvolution techniques: for the present work we
take advantage of a constrained deconvolution method. We illustrate with
numerical examples the potential of the proposed method for electron beam
diagnostics at the TESLA Test Facility (TTF) accelerator. Here we choose, for
emphasis, experiments aimed at the measure of the strongly non-Gaussian
electron bunch profile in the TTF femtosecond-mode operation. We demonstrate
that a tandem combination of a picosecond streak camera and a CSR spectrometer
can be used to extract shape information from electron bunches with a narrow
leading peak and a long tail.


title: X-ray polarimetry with an active-matrix pixel proportional counter

abstract:
  We report the first results from an X-ray polarimeter with a micropattern gas
proportional counter using an amorphous silicon active matrix readout. With
100% polarized X-rays at 4.5 keV, we obtain a modulation factor of 0.33 +/-
0.03, confirming previous reports of the high polarization sensitivity of a
finely segmented pixel proportional counter. The detector described here has a
geometry suitable for the focal plane of an astronomical X-ray telescope.
Amorphous silicon readout technology will enable additional extensions and
improvements.


title:
Electronic structure calculations for PrFe4P12 filled skutterudite using
  Extended Huckel tight-binding method

abstract:
  To get insight into the electronic properties of PrFe4P12 skutterudite, band
electronic structure calculations, Total and Projected Density of States,
Crystal Orbital Overlap Population and Mulliken Population Analysis were
performed. The energy bands yield a semi metallic behavior with a direct gap
(at gamma) of 0.02 eV. Total and Projected Density of States provided
information of the contribution from each orbital of each atom to the total
Density of States. Moreover, the bonding strength between some atoms within the
unit cell was obtained. Mulliken Population analysis suggests ionic behavior
for this compound.


title: Neutrino Oscillations for Dummies

abstract:
  The reality of neutrino oscillations has not really sunk in yet. The
phenomenon presents us with purely quantum mechanical effects over macroscopic
time and distance scales (milliseconds and 1000s of km). In order to help with
the pedagogical difficulties this poses, I attempt here to present the physics
in words and pictures rather than math. No disrespect is implied by the title;
I am merely borrowing a term used by a popular series of self-help books.


title:
Sound velocity and acoustic nonlinearity parameter for fluids.
  Thermodynamic premises

abstract:
  New theoretical formulae of the sound velocity and the B/A nonlinearity
parameter for some fluids are presented in the paper. Semi--ideal and van der
Waals models of gas are considered and the parameters are compared to
experiment data. The liquid water model for equation of state, given by Jeffery
and Austin analytical equation, is considered also and modified on the basis of
acoustic data .