title: Local inverses of shift maps along orbits of flows

abstract:
  Let $M$ be a smooth manifold and $F$ be a vector field on $M$. My article
["Smooth shifts along trajectories of flows", Topol. Appl. 130 (2003) 183-204,
arXiv:math/0106199] concerning the homotopy types of the group of
diffeomorphisms preserving orbits of $F$ contains two errors. They imply that
the principal statement of that paper holds under additional assumptions on
$F$. Unfortunately this result was essentially used in another paper of mine
["Homotopy types of stabilizers and orbits of Morse functions on surfaces" Ann.
Glob. Anal. Geom., 29 no. 3, (2006) 241-285, arXiv:math/0310067]. The aim of
this article is to expose the results of the first paper in a right way, extend
them to a larger class of flows with degenerate singularities, and show that
the results of the second paper remain true.


title: Homology representations arising from the half cube

abstract:
  We construct a CW decomposition $C_n$ of the $n$-dimensional half cube in a
manner compatible with its structure as a polytope. For each $3 \leq k \leq n$,
the complex $C_n$ has a subcomplex $C_{n, k}$, which coincides with the clique
complex of the half cube graph if $k = 4$. The homology of $C_{n, k}$ is
concentrated in degree $k-1$ and furthermore, the $(k-1)$-st Betti number of
$C_{n, k}$ is equal to the $(k-2)$-nd Betti number of the complement of the
$k$-equal real hyperplane arrangement. These Betti numbers, which also appear
in theoretical computer science, numerical analysis and engineering, are the
coefficients of a certain Pascal-like triangle (Sloane's sequence A119258). The
Coxeter groups of type $D_n$ act naturally on the complexes $C_{n, k}$, and
thus on the associated homology groups.


title:
Suppression of d-wave superconductivity in the checkerboard Hubbard
  model

abstract:
  Using a dynamical cluster quantum Monte Carlo approximation we investigate
the d-wave superconducting transition temperature $T_c$ in the doped 2D
repulsive Hubbard model with a weak inhomogeneity. The inhomogeneity is
introduced in the hoppings $\tp$ and $t$ in the form of a checkerboard pattern
where $t$ is the hopping within a $2\times2$ plaquette and $\tp$ is the hopping
between the plaquettes. We find inhomogeneity suppresses $T_c$. The
characteristic spin excitation energy and the strength of d-wave pairing
interaction decrease with decreasing $T_c$ suggesting a strong correlation
between these quantities.


title:
Optimizing the regimes of Advanced LIGO gravitational wave detector for
  multiple source types

abstract:
  We develop here algorithms which allow to find regimes of signal-recycled
Fabry-Perot--Michelson interferometer (for example, Advanced LIGO), optimized
concurrently for two (binary inspirals + bursts) and three (binary inspirals +
bursts + millisecond pulsars) types of gravitational waves sources. We show
that there exists a relatevely large area in the interferometer parameters
space where the detector sensitivity to the first two kinds of sources differs
only by a few percent from the maximal ones for each kind of source. In
particular, there exists a specific regime where this difference is ~0.5 for
both of them. Furthermore we show that even more multipurpose regimes are also
possible, that provide significant sensitivity gain for millisecond pulsars
with only minor sensitivity degradation for binary inspirals and bursts.


title: A Quick Verification of the 2-D Galaxy Distribution with SDSS Data

abstract:
  We present source code for the computer algebra system Mathematica that
analyzes the distribution of nearby Galaxies using SDSS data. Download
instructions are given, thus within 10 minutes, the reader can verify that
galaxies are distributed in an essentially non-homogeneous manner and cluster
on 2-dimensional structures. The short code uses a simple method inspired by
Minkowski functionals: the distances to the next neighbors are calculated and
compared to random distributions in three and two dimensions. The observed
distance distribution corresponds clearly to the latter case. The paper may
also be helpful for nonexpert scientists to get started with SDSS data
analysis.


title:
Relative Chow-Kunneth decompositions for conic bundles and Prym
  varieties

abstract:
  We construct a relative Chow-Kunneth decomposition for a conic bundle over a
surface such that the middle projector gives the Prym variety of the associated
double covering of the discriminant of the conic bundle. This gives a
refinement (up to an isogeny) of Beauville's theorem on the relation between
the intermediate Jacobian of the conic bundle and the Prym variety of the
double covering.


title:
The Doppler shift due to WMAP's spin mimics anisotropies in the cosmic
  microwave background

abstract:
  This paper has been withdrawn because its ideas have been incorporated into
arXiv:0905.3971 and explained much better there.


title:
Bloch electrons interacting with an external electromagnetic field and
  Bloch electrons in interaction

abstract:
  We apply a general method developed recently for the derivation of the
diagonal representation of an arbitrary matrix valued quantum Hamiltonian to
the particular case of Bloch electrons in an external electromagnetic field. We
find the diagonal representation as a series expansion to the second order in
$\hbar .$ This result is the basis for the determination of the effective
in-band Hamiltonian of interacting Bloch electrons living in different energy
bands. Indeed, the description of effects such as magnetic moment-moment
interactions mediated by the magnetic part of the full electromagnetic
interaction requires a computation to second order in $\hbar $. It is found
that the electronic current is made of two contributions: the first one comes
from the velocity and the second one is a magnetic moment current similar to
the spin current for Dirac particles. This last contribution is responsible for
the interaction between magnetic moments similarly to the spin-spin interaction
in the Breit Hamiltonian for Dirac electrons in interaction.


title: Threshold fields for antiparallel ferroelectric domain wall motion

abstract:
  While an ideal antiparallel ferroelectric wall is considered a unit cell in
width (~0.5nm), we show using phase field modeling that the threshold field for
moving this wall dramatically drops by 2-3 orders of magnitude if the wall were
diffuse by only ~2-3nm. Since antiparallel domain walls are symmetry allowed in
all ferroelectrics, and since domain wall broadening on nanometer scale is
widely reported in literature, this mechanism is generally applicable to all
ferroelectrics.


title: Using Charged Particle Imaging to Study Ultracold Plasma Expansion

abstract:
  We develop a projection imaging technique to study ultracold plasma dynamics.
We image the charged particle spatial distributions by extraction with a
high-voltage pulse onto a position-sensitive detector. Measuring the 2D width
of the ion image at later times (the ion image size in the first 20 $\mu$s is
dominated by the Coulomb explosion of the dense ion cloud), we extract the
plasma expansion velocity. These velocities at different initial electron
temperatures match earlier results obtained by measuring the plasma oscillation
frequency. The electron image size slowly decreases during the plasma lifetime
because of the strong Coulomb force of the ion cloud on the electrons, electron
loss and Coulomb explosion effects.


title: Recoherence by Squeezed States in Electron Interferometry

abstract:
  Coherent electrons coupled to the quantized electromagnetic field undergo
decoherence which can be viewed as due either to fluctuations of the
Aharonov-Bohm phase or to photon emission. When the electromagnetic field is in
a squeezed vacuum state, it is possible for this decoherence to be reduced,
leading to the phenomenon of recoherence. This recoherence effect requires
electrons which are emitted at selected times during the cycle of the excited
mode of the electromagnetic field. We show that there are bounds on the degree
of recoherence which are analogous to quantum inequality restriction on
negative energy densities in quantum field theory. We make some estimates of
the degree of recoherence, and show that although small, it may be observable.


title: Galaxy rotation curves: the effect of j x B force

abstract:
  Using the Galaxy as an example, we study the effect of j x B force on the
rotational curves of gas and plasma in galaxies. Acceptable model for the
galactic magnetic field and plausible physical parameters are used to fit the
flat rotational curve for gas and plasma based on the observed baryonic
(visible) matter distribution and j x B force term in the static MHD equation
of motion. We also study the effects of varied strength of the magnetic field,
its pitch angle and length scale on the rotational curves. We show that j x B
force does not play an important role on the plasma dynamics in the
intermediate range of distances 6-12 kpc from the centre, whilst the effect is
sizable for larger r (r > 15 kpc), where it is the most crucial.

categories: astro-ph astro-ph.CO astro-ph.GA physics.plasm-ph


title:
On a Theorem on sums of the form 1+2^(2^n)+2^(2^n+1)+...+2^(2^n+m) and a
  result linking Fermat with Mersenne numbers

abstract:
  In his book "250 Problems in Elementary Number Theory", W.Sierpinski shows
that the numbers 1+2^(2^n)+2^(2^n+1) are divisible by 21; for n=1,2,.... In
this paper, we prove a similar but more general result.Consider the natural
numbers of the form I(n.m)= 1+2^(2^n)+2^(2^n+1)+...+2^(2^n+m).In Theorem 1 we
prove that for every odd integer N greater than 1, there exist infinitely many
natural numbers n and m such that the integers I(n.m) are divisible by N. We
give an explicit construction of the numbers n and m, for a given N. As an
example, when N=31, and with n=4k and m=94+124i, the numbers I(n,m) are
divisible by 31. A similar example is offered for N=(31)(7)=217. In Theorem 2,
we prove a result pertaining to Mersenne numbers.There are also three
Corollaries in this work, one of which deals with Fermat numbers.


title:
CURiuos Variables Experiment (CURVE): Variable Stars in the metal-poor
  Globular Cluster M56

abstract:
  We have surveyed a 6.5' x 6.5' field centered on the globular cluster M56
(NGC 6779) in search for variable stars. We have detected seven variables,
among which two objects are new identifications. One of the new variables is an
RR Lyrae star, the third such star in M56. Comparison of the new observations
and old photometric data for an RV Tauri variable V6 indicates a likely period
change in the star. Its slow and negative rate of -0.005+/-0.003 d/yr would
disagree with post-AGB evolution, however this could be a result of blue-loop
evolution and/or random fluctuations of the period.


title: Higgs Decays and Brane Gravi-vectors

abstract:
  Higgs boson decays in flexible brane world models with stable, massive
gravi-vectors are considered. Such vectors couple bilinearly to the Standard
Model fields through either the Standard Model energy-momentum tensor, the weak
hypercharge field strength or the Higgs scalar. The role of the coupling
involving the extrinsic curvature is highlighted. It is found that within the
presently allowed parameter space, the decay rate of the Higgs into two
gravi-vectors (which would appear as an invisible Higgs decay) can be
comparable to the rate for any of the Standard Model decay modes.


title: Stirring trapped atoms into fractional quantum Hall puddles

abstract:
  We theoretically explore the generation of few-body analogs of fractional
quantum Hall states. We consider an array of identical few-atom clusters
(n=2,3,4), each cluster trapped at the node of an optical lattice. By
temporally varying the amplitude and phase of the trapping lasers, one can
introduce a rotating deformation at each site. We analyze protocols for
coherently transferring ground state clusters into highly correlated states,
producing theoretical fidelities in excess of 99%.


title:
Analysis of performance of three- and five-stack achromatic half-wave
  plates at millimeter wavelengths

abstract:
  We study the performance of achromatic half-wave plates (AHWP) as a function
of their construction parameters, the detection bandwidth of a power detector
operating in the millimeter wave band, and the spectral shape of the incident
radiation. We focus particular attention on the extraction of the degree of
incident polarization and its orientation angle from the intensity measured as
a function of AHWP rotation angle, which we call the IVA (intensity versus
angle). We quantify the phase offset of the IVA and point to potential
systematic errors in the extraction of this offset in cases where the incident
spectrum is not sufficiently well known. We show how the phase offset and
modulation efficiency of the AHWP depend on the relative angles between the
plates in the stack and find that high modulation efficiency can be achieved
with alignment accuracy of few degrees.


title: Superconformal Chern-Simons Theories and AdS_4/CFT_3 Correspondence

abstract:
  We discuss the N=2 superspace formulation of the N=8 superconformal
Bagger-Lambert-Gustavsson theory, and of the N=6 superconformal
Aharony-Bergman-Jafferis-Maldacena U(N)xU(N) Chern-Simons theory. In
particular, we prove the full SU(4) R-symmetry of the ABJM theory. We then
consider orbifold projections of this theory that give non-chiral and chiral
(U(N)xU(N))^n superconformal quiver gauge theories. We argue that these
theories are dual to certain AdS_4 x S^7/(Z_n x Z_k) backgrounds of M-theory.
We also study a SU(3) invariant mass term in the superpotential that makes the
N=8 theory flow to a N=2 superconformal gauge theory with a sextic
superpotential. We conjecture that this gauge theory is dual to the U(1)_R x
SU(3) invariant extremum of the N=8 gauged supergravity, which was discovered
by N. Warner 25 years ago and whose uplifting to 11 dimensions was found more
recently.


title:
A Realistic Formalism for 4N Bound State in a Three-Dimensional
  Yakubovsky Scheme

abstract:
  A spin-isospin dependent Three-Dimensional formalism based on the momentum
vectors for the four-nucleon bound state is presented. The four-nucleon
Yakubovsky equations with two- and three-nucleon interactions are formulated as
a function of the vector Jacobi momenta. Our formalism, according to the number
of spin-isospin states that one takes into account, leads to only a strictly
finite number of the coupled three-dimensional integral equations to be solved.
The evaluation of the transition and permutation operators as well as the
coordinate transformations due to considering the continuous angle variables
instead of the discrete angular momentum quantum numbers are less complicated
in comparison with partial wave representation. With respect to partial wave
the present formalism with the smaller number of equations leads to higher
dimensionality of the integral equations. We have concluded that
Three-Dimensional formalism is less cumbersome for considering the
three-nucleon forces.


title:
Assembling the Building Blocks of Giant Planets around Intermediate Mass
  Stars

abstract:
  We examine a physical process that leads to the efficient formation of gas
giant planets around intermediate mass stars. In the gaseous protoplanetary
disks surrounding rapidly-accreting intermediate-mass stars we show that the
midplane temperature (heated primarily by turbulent dissipation) can reach >
1000 K out to 1 AU. Thermal ionization of this hot gas couples the disk to the
magnetic field, allowing the magneto-rotational instability (MRI) to generate
turbulence and transport angular momentum. Further from the central star the
ionization fraction decreases, decoupling the disk from the magnetic field and
reducing the efficiency of angular momentum transport. As the disk evolves
towards a quasi-steady state, a local maximum in the surface density and in the
midplane pressure both develop at the inner edge of the MRI-dead zone, trapping
inwardly migrating solid bodies. Small particles accumulate and coagulate into
planetesimals which grow rapidly until they reach isolation mass. In contrast
to the situation around solar type stars, we show that the isolation mass for
cores at this critical radius around the more massive stars is large enough to
promote the accretion of significant amounts of gas prior to disk depletion.
Through this process, we anticipate a prolific production of gas giants at ~1
AU around intermediate-mass stars.


title:
Cosmological Shocks in Adaptive Mesh Refinement Simulations and the
  Acceleration of Cosmic Rays

abstract:
  We present new results characterizing cosmological shocks within adaptive
mesh refinement N-Body/hydrodynamic simulations that are used to predict
non-thermal components of large-scale structure. This represents the first
study of shocks using adaptive mesh refinement. We propose a modified algorithm
for finding shocks from those used on unigrid simulations that reduces the
shock frequency of low Mach number shocks by a factor of ~3. We then apply our
new technique to a large, (512 Mpc/h)^3, cosmological volume and study the
shock Mach number (M) distribution as a function of pre-shock temperature,
density, and redshift. Because of the large volume of the simulation, we have
superb statistics that results from having thousands of galaxy clusters. We
find that the Mach number evolution can be interpreted as a method to visualize
large-scale structure formation. Shocks with Mach<5 typically trace mergers and
complex flows, while 5<Mach<20 and Mach>20 generally follow accretion onto
filaments and galaxy clusters, respectively. By applying results from nonlinear
diffusive shock acceleration models using the first-order Fermi process, we
calculate the amount of kinetic energy that is converted into cosmic ray
protons. The acceleration of cosmic ray protons is large enough that in order
to use galaxy clusters as cosmological probes, the dynamic response of the gas
to the cosmic rays must be included in future numerical simulations.


title: Saturn in hot water: viscous evolution of the Enceladus torus

abstract:
  The detection of outgassing water vapor from Enceladus is one of the great
breakthroughs of the Cassini mission. The fate of this water once ionized has
been widely studied; here we investigate the effects of purely neutral-neutral
interactions within the Enceladus torus. We find that, thanks in part to the
polar nature of the water molecule, a cold (~180 K) neutral torus would undergo
rapid viscous heating and spread to the extent of the observed hydroxyl cloud,
before plasma effects become important. We investigate the physics behind the
spreading of the torus, paying particular attention to the competition between
heating and rotational line cooling. A steady-state torus model is constructed,
and it is demonstrated that the torus will be observable in the millimeter band
with the upcoming Herschel satellite. The relative strength of rotational lines
could be used to distinguish between physical models for the neutral cloud.


title:
Inside-out or Outside-in: The topology of reionization in the
  photon-starved regime suggested by Lyman-alpha forest data

abstract:
  We use a set of semi-numerical simulations based on Zel'dovich approximation,
friends-of-friends algorithm and excursion set formalism to generate
reionization maps of high dynamic range with a range of assumptions regarding
the distribution and luminosity of ionizing sources and the spatial
distribution of sinks for the ionizing radiation. We find that ignoring the
inhomogeneous spatial distribution of regions of high gas density where
recombinations are important -- as is often done in studies of this kind -- can
lead to misleading conclusions regarding the topology of reionization,
especially if reionization occurs in the photon-starved regime suggested by Lya
forest data. The inhomogeneous spatial distribution of recombinations
significantly reduces the mean free path of ionizing photons and the typical
size of coherently ionized regions. Reionization proceeds then much more as an
outside-in process. Low-density regions far from ionizing sources become
ionized before regions of high gas density not hosting sources of ionizing
radiation. The spatial distribution of sinks of ionization radiation also
significantly affects shape and amplitude the power spectrum of fluctuations of
21cm emission. The slope of the 21cm power spectrum as measured by upcoming
21cm experiments should be able to distinguish to what extent the topology of
reionization proceeds outside-in or inside-out while the evolution of the
amplitude of the power spectrum with increasing ionized mass fraction should be
sensitive to the spatial distribution and the luminosity of ionizing sources.


title:
Density Probability Distribution Functions in Supersonic Hydrodynamic
  and MHD Turbulence

abstract:
  We study the probability distribution function (PDF) of the mass density in
simulations of supersonic turbulence with properties appropriate for molecular
clouds. For this study we use Athena, a new higher-order Godunov code. We find
there are surprisingly similar relationships between the mean of the
time-averaged PDF and the turbulent Mach number for driven hydrodynamic and
strong-field MHD turbulence. There is, however, a large scatter about these
relations, indicating a high level of temporal and spatial variability in the
PDF. Thus, the PDF of the mass density is unlikely to be a good measure of
magnetic field strength. We also find the PDF of decaying MHD turbulence
deviates from the mean-Mach relation found in the driven case. This implies
that the instantaneous Mach number alone is not enough to determine the
statistical properties of turbulence that is out of equilibrium. The scatter
about the mean-Mach relation for driven turbulence, along with the large
departure of decaying turbulence PDFs from those of driven turbulence, may
illuminate one factor contributing to the large observed cloud-to-cloud
variation in the star formation rate per solar mass.


title: On Electromagnetic Wave Interaction with Dense Resonant Atom Medium

abstract:
  The excitation of atomic levels due to interaction with electromagnetic waves
became of interest in accelerator physics in relation to high efficiency charge
exchange injection into rings for high beam power applications. Usually, the
beam density is so small that its influence on the wave is completely
neglected. Here we consider the case of dense beams - the beam dimensions are
large as compared to light reflection length. This paper shows that the waves
can be trapped in the medium under these conditions. Moreover, the atoms with
induced dipole moments start to interact strongly with each other, leading to
possibility to create some atomic patterns when the medium is relatively cold.


title:
The Chandra ACIS Survey of M33 (ChASeM33): Investigating the Hot Ionized
  Medium in NGC604

abstract:
  NGC604 is the largest HII-region in M33, second only within the Local Group
to 30 Dor, and is important as a laboratory for understanding how massive young
stellar clusters interact with the surrounding interstellar medium. Here, we
present deep (300ks) X-ray imagery of NGC604 obtained as part of the Chandra
ACIS Survey of M33 (ChASeM33), which show highly structured X-ray emission
covering ~70% of the full Halpha extent of NGC604. The main bubbles and
cavities in NGC604 are filled with hot (kT=0.5keV) X-ray emitting gas and X-ray
spectra extracted from these regions indicate that the gas is thermal. For the
western part of NGC604 we derive an X-ray gas mass of ~4300M_sol and an
unabsorbed (0.35-2.5keV) X-ray luminosity of L_X = 9.3E35 erg/s. These values
are onsistent with a stellar mass loss bubble entirely powered by about 200
OB-stars. This result is remarkable because the standard bubble model tends to
underpredict the luminosity of X-ray bright bubbles and usually requires
additional heating from SNRs. Given a cluster age of ~3Myr it is likely that
the massive stars have not yet evolved into SNe. We detect two discrete spots
of enhanced and harder X-ray emission, which we consider to be fingerprints
from a reverse shock produced by a supersonic wind after it collided with the
shell wall. In the eastern part of NGC604 the X-ray gas mass amounts to
~1750M_sol. However, mass loss from young stars cannot account for the
unabsorbed X-ray luminosity of L_X = 4.8E35 erg/s. Off-center SNRs could
produce the additional luminosity. The bubbles in the east seem to be much
older and were most likely formed and powered by stars and SNe in the past.


title: The Christoffel-Darboux Kernel

abstract:
  A review of the uses of the CD kernel in the spectral theory of orthogonal
polynomials, concentrating on recent results.


title:
Probing the Magnetized Interstellar Medium Surrounding the Planetary
  Nebula Sh 2-216

abstract:
  We present 1420 MHz polarization images of a 2.5 X 2.5 degree region around
the planetary nebula (PN) Sh 2-216. The images are taken from the Canadian
Galactic Plane Survey (CGPS). An arc of low polarized intensity appears
prominently in the north-east portion of the visible disk of Sh 2-216,
coincident with the optically identified interaction region between the PN and
the interstellar medium (ISM). The arc contains structural variations down to
the ~1 arcminute resolution limit in both polarized intensity and polarization
angle. Several polarization-angle "knots" appear along the arc. By comparison
of the polarization angles at the centers of the knots and the mean
polarization angle outside Sh 2-216, we estimate the rotation measure (RM)
through the knots to be -43 +/- 10 rad/m^2. Using this estimate for the RM and
an estimate of the electron density in the shell of Sh 2-216, we derive a
line-of-sight magnetic field in the interaction region of 5.0 +/- 2.0 microG.
We believe it more likely the observed magnetic field is interstellar than
stellar, though we cannot completely dismiss the latter possibility. We
interpret our observations via a simple model which describes the ISM magnetic
field around Sh 2-216, and comment on the potential use of old PNe as probes of
the magnetized ISM.


title:
Extended multiwavelength fuzz around red quasars: observational
  appearance of radiative feedback in action

abstract:
  Red quasars are a population, characterized by significant extinction in UV,
which could be explained by absorption of dusty gas on a scale of a few kpc. We
show that the enhanced radiation-pressure drives the dusty gas to
supersonically expand and produces shocks. The shocks energize electrons to be
relativistic via the first Fermi acceleration. As a balance of shock
acceleration and synchrotron emission and inverse Compton scattering, the
maximum Lorentz factor of the electrons reaches as $\sim 10^6$. The shocked
interstellar medium appears as extended multiwavelength fuzz, in which
synchrotron emission from the electrons peaks at near infrared or UV bands and
inverse Compton scattering around 1.0GeV$-$0.1TeV. Future multiwavelength
images of the fuzz would provide new clues to study the details of radiative
feedback if red quasars could be a certain phase in evolutionary chains of
galaxies.


title:
Probes and Tests of Strong-Field Gravity with Observations in the
  Electromagnetic Spectrum

abstract:
  Neutron stars and black holes are the astrophysical systems with the
strongest gravitational fields in the universe. In this article, I review the
prospect of probing with observations of such compact objects some of the most
intriguing General Relativistic predictions in the strong-field regime: the
absence of stable circular orbits near a compact object and the presence of
event horizons around black-hole singularities. I discuss the need for a
theoretical framework within which future experiments will provide detailed,
quantitative tests of gravity theories. Finally, I summarize the constraints
imposed by current observations of neutron stars on potential deviations from
General Relativity.


title:
Highest weight categories arising from Khovanov's diagram algebra I:
  cellularity

abstract:
  This is the first of four articles studying some slight generalisations
H(n,m) of Khovanov's diagram algebra, as well as quasi-hereditary covers K(n,m)
of these algebras in the sense of Rouquier, and certain infinite dimensional
limiting versions. In this article we prove that H(n,m) is a cellular symmetric
algebra and that K(n,m) is a cellular quasi-hereditary algebra. In subsequent
articles, we relate these algebras to level two blocks of degenerate cyclotomic
Hecke algebras, parabolic category O and the general linear supergroup,
respectively.


title: On the Decay of Unparticles

abstract:
  We show that when the unparticle sector is coupled to the Standard Model,
unparticle excitations can decay to Standard Model particles. This radically
modifies the signals of unparticle production. We present a method for the
calculation of the decay lifetimes of unparticles. In a particular model, we
show that depending on their lifetime, unparticles can manifest themselves
through monojets, delayed events or prompt decays.


title: Superluminal Travel Made Possible (in two dimensions)

abstract:
  We argue that superluminal signal propagation is possible in consistent
Poincare invariant quantum field theories in two space-time dimensions,
provided spatial parity is broken. This happens due to existence of the
``instantaneous'' causal structure, with one of the light cone variables being
a global time. In two dimensions this causal structure is invariant under the
Poincare group if one gives up the spatial parity. As a non-trivial example of
a consistent interacting quantum field theory with this causal structure we
discuss a non-linear SO(1,1) sigma-model, where SO(1,1) is the Lorentz
symmetry. We show that this theory is asymptotically free and argue that this
model is also well defined non-perturbatively, at least for some values of
parameters. It provides an example of a microscopic Poincare invariant quantum
field theory with local action, but non-local physical properties. Being
coupled to gravity this ``instantaneous'' theory mixes with the Liouville
field. If proves to be consistent, the resulting model can be used to construct
(non-critical) string theories with very unconventional properties by
introducing the instantaneous causal structure on the world-sheet.


title:
Maximum Wavelength of Confined Quarks and Gluons and Properties of
  Quantum Chromodynamics

abstract:
  Because quarks and gluons are confined within hadrons, they have a maximum
wavelength of order the confinement scale. Propagators, normally calculated for
free quarks and gluons using Dyson-Schwinger equations, are modified by
bound-state effects in close analogy to the calculation of the Lamb shift in
atomic physics. Because of confinement, the effective quantum chromodynamic
coupling stays finite in the infrared. The quark condensate which arises from
spontaneous chiral symmetry breaking in the bound state Dyson-Schwinger
equation is the expectation value of the operator $\bar q q$ evaluated in the
background of the fields of the other hadronic constituents, in contrast to a
true vacuum expectation value. Thus quark and gluon condensates reside within
hadrons. The effects of instantons are also modified. We discuss the
implications of the maximum quark and gluon wavelength for phenomena such as
deep inelastic scattering and annihilation, the decay of heavy quarkonia, jets,
and dimensional counting rules for exclusive reactions. We also discuss
implications for the zero-temperature phase structure of a vectorial SU($N$)
gauge theory with a variable number $N_f$ of massless fermions.


title: Manin's conjecture on a nonsingular quartic del Pezzo surface

abstract:
  Given a nonsingular quartic del Pezzo surface, a conjecture of Manin predicts
the density of rational points on the open subset of the surface formed by
deleting the lines. We prove that this prediction is of the correct order of
magnitude for a particular surface.


title:
Scalar radiation emitted from a rotating source around a
  Reissner-Nordstrom black hole

abstract:
  We investigate the radiation emitted from a scalar source in circular orbit
around a Reissner-Nordstrom black hole. Particle and energy emission rates are
analytically calculated in the low- and high-frequency regimes and shown to be
in full agreement with a numerical calculation. Our investigation is connected
with the recent discussion on the validity of the cosmic censorship conjecture
in the quantum realm.


title:
A basis of bideterminants for the coordinate ring of the orthogonal
  group

abstract:
  We give a basis of bideterminants for the coordinate ring K[O(n)] of the
orthogonal group O(n,K), where K is an infinite field of characteristic not 2.
The bideterminants are indexed by pairs of Young tableaux which are
O(n)-standard in the sense of King-Welsh. We also give an explicit filtration
of K[O(n)] as an O(n,K)-bimodule, whose factors are isormorphic to the tensor
product of orthogonal analogues of left and right Schur modules.


title: Quantum Search Algorithm for Set Operation

abstract:
  The operations of data set, such as intersection, union and complement, are
the fundamental calculation in mathematics. It's very significant that
designing fast algorithm for set operation. In this paper, the quantum
algorithm for intersection is presented. And its running time is
sqrt(|A|*|B|*|C|) for set operation C = A intersection B, while classical
computation needs O (|A| *|B|) steps of computation in general, where |.|
denotes the size of set. The presented algorithm is the combination of Grover's
algorithm, classical memory and classical iterative computation, and the
combination method decrease the complexity of designing quantum algorithm.The
method can be used to design other set operations also. Keywords: Set
operation, General Grover iteration, Grover's algorithm


title: Model category extensions of the Pirashvili-S{\l}omi\'{n}ska theorems

abstract:
  We describe the class of semi-stable model categories, which generalize the
equivalence of finite products and coproducts in abelian and stable model
categories, and use this to establish Morita equivalences among categories of
functors. We provide a construction of pairs of small categories--known as
conjugate pairs--whose associated categories of diagrams are Quillen equivalent
in the semi-stable setting. We frame our development in the context of Morita
theory, following Slominska's work on similar questions for categories of
functors enriched over and taking values in R-modules.


title: $B \to \gamma \gamma$ in an ACD model

abstract:
  We present a full calculation of the amplitudes for $B_{d[s]} \to \gamma
\gamma$ in a simple ACD model that extends an incomplete one in a previous
paper. We find cancellations between the contributions from different KK towers
and a small decrease relative to the SM predictions. It is conjectured that
radiative QCD corrections might actually lead to an enhancement in the
branching ratios and {\bf CP} asymmetries, but no more than modest ones.


title:
Experimental test of curvature-driven dynamics in the phase ordering of
  a two dimensional liquid crystal

abstract:
  We study electric field driven deracemization in an achiral liquid crystal
through the formation and coarsening of chiral domains. It is proposed that
deracemization in this system is a curvature-driven process. We test this
prediction using the exact result for the distribution of hull-enclosed areas
in two-dimensional coarsening in non-conserved scalar order parameter dynamics
recently obtained [J.J. Arenzon et al., Phys. Rev. Lett. 98, 061116 (2007)].
The experimental data are in very good agreement with the theory. We thus
demonstrate that deracemization in such bent-core liquid crystals belongs to
the Allen-Cahn universality class, and that the exact formula, which gives us
the statistics of domain sizes during coarsening, can also be used as a strict
test for this dynamic universality class.


title: On the Superdistribution of Digital Goods

abstract:
  Business models involving buyers of digital goods in the distribution process
are called superdistribution schemes. We review the state-of-the art of
research and application of superdistribution and propose systematic approach
to market mechanisms using super-distribution and technical system
architectures supporting it. The limiting conditions on such markets are of
economic, legal, technical, and psychological nature.


title:
An Alternative Quantization Protocol for the History Dependent Parrondo
  Game

abstract:
  Earlier work on the quantization of the history dependent (HD) Parrondo game
by Flitney, Ng, and Abbott led to the FNA protocol. We propose an alternative
quantization protocol for this game which differs from the FNA protocol in
various aspects.


title:
Stretching Riemannian spherical solar dynamo model from differentia
  rotation

abstract:
  Stretching solar dynamos from differential rotation in a Riemannian manifold
setting is presented. The spherical model follows closely a twisted magnetic
flux tube Riemannian geometrical model or flux rope in solar physics, presented
previously by Ricca [Solar Physics (1997)]. The spherical model presented here
present new and interesting feature concerning its connection with spherical
steady solar dynamos. One of this new feature is represented by the fact that
the by considering poloidal magnetic field component much weaker than its
toroidal counterpart, one obtains a stretch dynamo action where the Riemannian
solar spherical line element is proportional to differential rotation. This
result is obtained also by using the Vainshtein-Zeldovich stretch, twist and
fold (STF) method to generate dynamos. One notes that for high magnetic
Reynolds of $R{m}=O({10^{7}})$ the dynamo action is present for a corresponding
small stretching factor of $K^{2}=1.6$ where $K^{2}=1$ represents the
unstretched dynamo. The constant stretched dynamos considered here are shown to
be Riemann-flat, where the Riemann curvature tensor vanishes. Solar cycle
dynamos are therefore compatible with the Riemann-flat stretching dynamo model
from solar differential rotation presented here.


title:
On the Issue of the \zeta Series Convergence and Loop Corrections in the
  Generation of Observable Primordial Non-Gaussianity in Slow-Roll Inflation.
  Part I: the Bispectrum

abstract:
  We show in this paper that it is possible to attain very high, {\it including
observable}, values for the level of non-gaussianity f_{NL} associated with the
bispectrum B_\zeta of the primordial curvature perturbation \zeta, in a
subclass of small-field {\it slow-roll} models of inflation with canonical
kinetic terms. Such a result is obtained by taking care of loop corrections
both in the spectrum P_\zeta and the bispectrum B_\zeta. Sizeable values for
f_{NL} arise even if \zeta is generated during inflation. Five issues are
considered when constraining the available parameter space: 1. we must ensure
that we are in a perturbative regime so that the \zeta series expansion, and
its truncation, are valid. 2. we must apply the correct condition for the
(possible) loop dominance in B_\zeta and/or P_\zeta. 3. we must satisfy the
spectrum normalisation condition. 4. we must satisfy the spectral tilt
constraint. 5. we must have enough inflation to solve the horizon problem.


title:
Spectrum of Magnetic Dissipation and Horizontal Electric Currents in the
  Solar Photosphere

abstract:
  A proxy for horizontal electric currents in the solar photosphere was
suggested. For a set of evolving active regions (ARs) observed with {\it Solar
and Heliospheric Observatory (SOHO)} Michelson Doppler Imager (MDI) in the high
resolution mode, the dissipation spectrum, $k^2E(k)$, and the spatial structure
of dissipation, i.e., the Stokes dissipation function $\epsilon(x,y)$, were
calculated from the observed $B_z$ component of the magnetic field. These
functions allowed us to calculate (a part of) the horizontal electric current
density in the photosphere. It was shown that as an active region emerges,
large-scale horizontal electric currents are gradually generated and determine
a bulk of dissipation. When an active region decays, the large-scale horizontal
currents decay faster than the small-scale ones. The density of horizontal
currents in active regions is in the range of $<j_h > \sim (0.008 - 0.028)$
A/m$^2$, that is compatible with the density of vertical currents in active
regions. We suggest two possible mechanisms for generation of such horizontal
currents in the photosphere. One of them is the drift motions of charged
particles in the medium of varying plasma pressure gradient in a horizontal
plane at the periphery of a sunspot. Such a drift can produce quasi-circular
closed horizontal currents around sunspots. Another possibility could be an
existence of horizontal axial current inside a highly twisted horizontal
magnetic structure laying in the photosphere along the magnetic neutral line.
The horizontal currents may contribute significantly to the dynamics of the
photosphere/corona coupling, as well as the estimation of non-potentiality of
ARs.


title:
A Search for H2CO 6cm Emission toward Young Stellar Objects III: VLA
  Observations

abstract:
  We report the results of our third survey for formaldehyde (H2CO) 6cm maser
emission in the Galaxy. Using the Very Large Array, we detected two new H2CO
maser sources (G23.01-0.41 and G25.83-0.18), thus increasing the sample of
known H2CO maser regions in the Galaxy to seven. We review the characteristics
of the G23.01-0.41 and G25.83-0.18 star forming regions. The H2CO masers in
G23.01-0.41 and G25.83-0.18 share several properties with the other known H2CO
masers, in particular, emission from rich maser environments and close
proximity to very young massive stellar objects.


title: Bits through ARQs

abstract:
  A fundamental problem in dynamic frequency reuse is that the cognitive radio
is ignorant of the amount of interference it inflicts on the primary license
holder. A model for such a situation is proposed and analyzed. The primary
sends packets across an erasure channel and employs simple ACK/NAK feedback
(ARQs) to retransmit erased packets. Furthermore, its erasure probabilities are
influenced by the cognitive radio's activity. While the cognitive radio does
not know these interference characteristics, it can eavesdrop on the primary's
ARQs. The model leads to strategies in which the cognitive radio adaptively
adjusts its input based on the primary's ARQs thereby guaranteeing the primary
exceeds a target packet rate. A relatively simple strategy whereby the
cognitive radio transmits only when the primary's empirical packet rate exceeds
a threshold is shown to have interesting universal properties in the sense that
for unknown time-varying interference characteristics, the primary is
guaranteed to meet its target rate. Furthermore, a more intricate version of
this strategy is shown to be capacity-achieving for the cognitive radio when
the interference characteristics are time-invariant.


title: High Energy Gamma Rays from Protons Hitting Compact Objects

abstract:
  In a previous paper the spectrum of positrons produced by matter initially at
rest falling onto a massive compact object was calculated. In this paper this
calculation is generalized to obtain both the spectrum of in-flight positron
annihilation and pi0 decay gamma rays produced when protons with a cosmic
ray-like spectrum hit the surface. The resulting pi0 decay gamma ray spectrum
reflects the high energy proton energy spectrum, and is largely independent of
the mass of the compact object. One notable prediction for all compact objects
is a dip in the spectrum below 70 MeV. As applied to the 10^6 solar mass
massive compact object near to the center of our galaxy, our theory shows
promise for explaining the gamma rays coming from the galactic center as
observed by both the Compton satellite and HESS ground based array.


title:
First-principles calculation of DNA looping in tethered particle
  experiments

abstract:
  We calculate the probability of DNA loop formation mediated by regulatory
proteins such as Lac repressor (LacI), using a mathematical model of DNA
elasticity. Our model is adapted to calculating quantities directly observable
in Tethered Particle Motion (TPM) experiments, and it accounts for all the
entropic forces present in such experiments. Our model has no free parameters;
it characterizes DNA elasticity using information obtained in other kinds of
experiments. [...] We show how to compute both the "looping J factor" (or
equivalently, the looping free energy) for various DNA construct geometries and
LacI concentrations, as well as the detailed probability density function of
bead excursions. We also show how to extract the same quantities from recent
experimental data on tethered particle motion, and then compare to our model's
predictions. [...] Our model successfully reproduces the detailed distributions
of bead excursion, including their surprising three-peak structure, without any
fit parameters and without invoking any alternative conformation of the LacI
tetramer. Indeed, the model qualitatively reproduces the observed dependence of
these distributions on tether length (e.g., phasing) and on LacI concentration
(titration). However, for short DNA loops (around 95 basepairs) the experiments
show more looping than is predicted by the harmonic-elasticity model, echoing
other recent experimental results. Because the experiments we study are done in
vitro, this anomalously high looping cannot be rationalized as resulting from
the presence of DNA-bending proteins or other cellular machinery. We also show
that it is unlikely to be the result of a hypothetical "open" conformation of
the LacI tetramer.


title: On the study of force-balance percolation

abstract:
  We study models of correlated percolation where there are constraints on the
occupation of sites that mimic force-balance, i.e. for a site to be stable
requires occupied neighboring sites in all four compass directions in two
dimensions. We prove rigorously that $p_c<1$ for the two-dimensional models
studied. Numerical data indicate that the force-balance percolation transition
is discontinuous with a growing crossover length, with perhaps the same form as
the jamming percolation models, suggesting the same underlying mechanism
driving the transition in both cases. In other words, force-balance percolation
and jamming percolation may indeed belong to the same universality class. We
find a lower bound for the correlation length in the connected phase and that
the correlation function does not appear to be a power law at the transition.
Finally, we study the dynamics of the culling procedure invoked to obtain the
force-balance configurations and find a dynamical exponent similar to that
found in sandpile models.


title: Amplification of Fluctuations in a Spinor Bose Einstein Condensate

abstract:
  Dynamical instabilities due to spin-mixing collisions in a $^{87}$Rb F=1
spinor Bose-Einstein condensate are used as an amplifier of quantum spin
fluctuations. We demonstrate the spectrum of this amplifier to be tunable, in
quantitative agreement with mean-field calculations. We quantify the
microscopic spin fluctuations of the initially paramagnetic condensate by
applying this amplifier and measuring the resulting macroscopic magnetization.
The magnitude of these fluctuations is consistent with predictions of a
beyond-mean-field theory. The spinor-condensate-based spin amplifier is thus
shown to be nearly quantum-limited at a gain as high as 30 dB.


title: Underbarrier interference and Euclidean resonance

abstract:
  Quantum tunneling from a thin wire or a thin film through a static potential
barrier in a zero magnetic field is studied. The wire or the film should
satisfy a condition of transverse quantization of levels and be inhomogeneous.
Depending on a form of the inhomogeneity the tunneling scenario can
dramatically differ from the conventional scheme of an exponential decay of a
probability density inside the barrier. This happens due to interference of
various underbarrier paths, which are collected at some points giving rise to a
trans-barrier state of a large amplitude. As a result, the tunneling
probability through an almost classical barrier can be not exponentially small.
This is a phenomenon of Euclidean resonance studied earlier for tunneling
across nonstationary barriers.


title: Tomographic femtosecond X-ray diffractive imaging

abstract:
  A method is proposed for obtaining three simultaneous projections of a target
from a single radiation pulse, which also allows the relative orientation of
successive targets to be determined. The method has application to femtosecond
X-ray diffraction, and does not require solution of the phase problem. We show
that the principle axes of a compact charge-density distribution can be
obtained from projections of its autocorrelation function, which is directly
accessible in diffraction experiments. The results may have more general
application to time resolved tomographic pump-probe experiments and time-series
imaging.


title: An Elementary Derivation of the Five Dimensional Myers-Perry Metric

abstract:
  We derive the five dimensional Myers-Perry metric via an elementary method to
solve the vacuum Einstein field equations directly. This method firstly
proposed by Clotz is very simple since it merely involves four components of
Ricci tensor and only requires us to deal with some equations without second
derivatives' terms when the metric ansatz is assumed to take an appropriate
form.


title:
It\^o's formula for the $L_{p}$-norm of stochastic $W^{1}_{p}$-valued
  processes

abstract:
  We prove It\^o's formula for the $L_{p}$-norm of a stochastic
$W^{1}_{p}$-valued processes appearing in the theory of SPDEs in divergence
form.


title:
Idling Magnetic White Dwarf in the Synchronizing Polar BY Cam. The
  Noah-2 Project

abstract:
  Results of a multi-color study of the variability of the magnetic cataclysmic
variable BY Cam are presented. The observations were obtained at the Korean
1.8m and Ukrainian 2.6m, 1.2m and 38-cm telescopes in 2003-2005, 56
observational runs cover 189 hours. The variations of the mean brightness in
different colors are correlated with a slope dR/dV=1.29(4), where the number in
brackets denotes the error estimates in the last digits. For individual runs,
this slope is much smaller ranging from 0.98(3) to 1.24(3), with a mean value
of 1.11(1). Near the maximum, the slope becomes smaller for some nights,
indicating more blue spectral energy distribution, whereas the night-to-night
variability has an infrared character. For the simultaneous UBVRI photometry,
the slopes increase with wavelength from dU/dR=0.23(1) to dI/dR=1.18(1). Such
wavelength dependence is opposite to that observed in non-magnetic cataclysmic
variables, in an agreement to the model of cyclotron emission. The principal
component analysis shows two (with a third at the limit of detection)
components of variablitity with different spectral energy distribution, which
possibly correspond to different regions of emission. The scalegram analysis
shows a highest peak corresponding to the 200-min spin variability, its quarter
and to the 30-min and 8-min QPOs. The amplitudes of all these components are
dependent on wavelength and luminosity state. The light curves were fitted by a
statistically optimal trigonometrical polynomial (up to 4-th order) to take
into account a 4-hump structure. The dependences of these parameters on the
phase of the beat period and on mean brightness are discussed. The amplitude of
spin variations increases with an increasing wavelength and with decreasing
brightness


title:
Resistance fluctuations and Aharonov-Bohm-type oscillations in antidot
  arrays in the quantum Hall regime

abstract:
  Resistance fluctuation phenomenon in antidot lattices in the quantum Hall
regime are studied. Magnetoresistance of finite antidot array systems in the
quantum Hall plateau transition regime exhibits two types of oscillatory
effect. One is the aperiodic resistance fluctuations (RFs) and the other is the
Aharonov-Bohm (AB)-type oscillations. Their dependences on the magnetic field
and the gate voltage are quite distinct. While the aperiodic RFs are attributed
to the complex evolution of the conducting network of compressible channels,
the AB-type oscillations are interpreted in terms of edge states formed around
individual antidots. The self-consistent screening effect is important for the
both phenomenon, whereas, the single electron charging effect plays a minor
role in the present case.


title:
Effect of atmospheric turbulence on propagation properties of optical
  vortices formed by using coherent laser beam arrays

abstract:
  In this paper, we consider the effect of the atmospheric turbulence on the
propagation of optical vertex formed from the radial coherent laser beam array,
with the initially well-defined phase distribution. The propagation formula of
the radial coherent laser array passing through the turbulent atmosphere is
analytically derived by using the extended Huygens-Fresnel diffraction
integral. Based on the derived formula, the effect of the atmospheric
turbulence on the propagation properties of such laser arrays has been studied
in great detail. Our main results show that the atmospheric turbulence may
result in the prohibition of the formation of the optical vortex or the
disappearance of the formed optical vortex, which are very different from that
in the free space. The formed optical vortex with the higher topological charge
may propagate over a much longer distance in the moderate or weak turbulent
atmosphere. After the sufficient long-distance atmospheric propagation, all the
output beams (even with initially different phase distributions) finally lose
the vortex property and gradually become the Gaussian-shaped beams, and in this
case the output beams actually become incoherent light fields due to the
decoherence effect of the turbulent atmosphere.


title: Schur Positivity and the $q$-Log-convexity of the Narayana Polynomials

abstract:
  Using Schur positivity and the principal specialization of Schur functions,
we provide a proof of a recent conjecture of Liu and Wang on the
$q$-log-convexity of the Narayana polynomials, and a proof of the second
conjecture that the Narayana transformation preserves the log-convexity. Based
on a formula of Br\"and$\mathrm{\acute{e}}$n which expresses the $q$-Narayana
numbers as the specializations of Schur functions, we derive several symmetric
function identities using the Littlewood-Richardson rule for the product of
Schur functions, and obtain the strong $q$-log-convexity of the Narayana
polynomials and the strong $q$-log-concavity of the $q$-Narayana numbers.


title: Are Microwave Induced Zero Resistance States Necessarily Static?

abstract:
  We study the effect of inhomogeneities in Hall conductivity on the nature of
the Zero Resistance States seen in the microwave irradiated two-dimensional
electron systems in weak perpendicular magnetic fields, and we show that
time-dependent domain patterns may emerge in some situations. For an annular
Corbino geometry, with an equilibrium charge density that varies linearly with
radius, we find a time-periodic non-equilibrium solution, which might be
detected by a charge sensor, such as an SET. For a model on a torus, in
addition to static domain patterns seen at high and low values of the
equilibrium charge inhomogeneity, we find that, in the intermediate regime, a
variety of nonstationary states can also exist. We catalog the possibilities we
have seen in our simulations. Within a particular phenomenological model, we
show that linearizing the nonlinear charge continuity equation about a
particularly simple domain wall configuration and analyzing the eigenmodes
allows us to estimate the periods of the solutions to the full nonlinear
equation.


title: Transcendence of Power Series for Some Number Theoretic Functions

abstract:
  We give a new proof of Fatou's theorem: {\em if an algebraic function has a
power series expansion with bounded integer coefficients, then it must be a
rational function.} This result is applied to show that for any non--trivial
completely multiplicative function from $\mathbb{N}$ to $\{-1,1\}$, the series
$\sum_{n=1}^\infty f(n)z^n$ is transcendental over $\mathbb{Z}[z]$; in
particular, $\sum_{n=1}^\infty \lambda(n)z^n$ is transcendental, where
$\lambda$ is Liouville's function. The transcendence of $\sum_{n=1}^\infty
\mu(n)z^n$ is also proved.


title: Higher Order Periodic Solutions of Coupled phi4 Models

abstract:
  We obtain several higher order exact periodic solutions of (i) a coupled
symmetric phi4 model in an external field, (ii) an asymmetric coupled phi4
model, (iii) an asymmetric-symmetric coupled phi4 model, in terms of Lame
polynomials of order two and obtain the corresponding hyperbolic solutions in
the appropriate limit. These solutions are unusual in the sense that while they
are the solutions of the coupled problems, they are not the solutions of the
corresponding uncoupled problems.

categories: math-ph cond-mat.mtrl-sci hep-th math.MP


title:
Competitive Design of Multiuser MIMO Systems based on Game Theory: A
  Unified View

abstract:
  This paper considers the noncooperative maximization of mutual information in
the Gaussian interference channel in a fully distributed fashion via game
theory. This problem has been studied in a number of papers during the past
decade for the case of frequency-selective channels. A variety of conditions
guaranteeing the uniqueness of the Nash Equilibrium (NE) and convergence of
many different distributed algorithms have been derived. In this paper we
provide a unified view of the state-of-the-art results, showing that most of
the techniques proposed in the literature to study the game, even though
apparently different, can be unified using our recent interpretation of the
waterfilling operator as a projection onto a proper polyhedral set. Based on
this interpretation, we then provide a mathematical framework, useful to derive
a unified set of sufficient conditions guaranteeing the uniqueness of the NE
and the global convergence of waterfilling based asynchronous distributed
algorithms.
  The proposed mathematical framework is also instrumental to study the
extension of the game to the more general MIMO case, for which only few results
are available in the current literature. The resulting algorithm is, similarly
to the frequency-selective case, an iterative asynchronous MIMO waterfilling
algorithm. The proof of convergence hinges again on the interpretation of the
MIMO waterfilling as a matrix projection, which is the natural generalization
of our results obtained for the waterfilling mapping in the frequency-selective
case.


title: On the Structure of the Fusion Ideal

abstract:
  We prove that there is a finite level-independent bound on the number of
relations defining the fusion ring of positive energy representations of the
loop group of a simple, simply connected Lie group. As an illustration, we
compute the fusion ring of $G_2$ at all levels.


title:
Flexible Time-Triggered Sampling in Smart Sensor-Based Wireless Control
  Systems

abstract:
  Wireless control systems (WCSs) often have to operate in dynamic environments
where the network traffic load may vary unpredictably over time. The sampling
in sensors is conventionally time triggered with fixed periods. In this
context, only worse-than-possible quality of control (QoC) can be achieved when
the network is underloaded, while overloaded conditions may significantly
degrade the QoC, even causing system instability. This is particularly true
when the bandwidth of the wireless network is limited and shared by multiple
control loops. To address these problems, a flexible time-triggered sampling
scheme is presented in this work. Smart sensors are used to facilitate dynamic
adjustment of sampling periods, which enhances the flexibility and resource
efficiency of the system based on time-triggered sampling. Feedback control
technology is exploited for adapting sampling periods in a periodic manner. The
deadline miss ratio in each control loop is maintained at/around a desired
level, regardless of workload variations. Simulation results show that the
proposed sampling scheme is able to deal with dynamic and unpredictable
variations in network traffic load. Compared to conventional time-triggered
sampling, it leads to much better QoC in WCSs operating in dynamic
environments.


title: Pseudo spin-orbit coupling of Dirac particles in graphene spintronics

abstract:
  We study the pseudo spin-orbital (SO) effects experienced by massive Dirac
particles in graphene, which can potentially be of a larger magnitude compared
to the conventional Rashba SO effects experienced by particles in a 2DEG
semiconductor heterostructure. In order to generate a uniform vertical pseudo
SO field, we propose an artificial atomic structure, consisting of a graphene
ring and a charged nanodot at the center which produces a large radial electric
field. In this structure, a large pseudo SO coupling strength can be achieved
by accelerating the Dirac particles around the ring, due to the small energy
gap in graphene and the large radial electric field emanating from the charged
nanodot. We discuss the theoretical possibility of harnessing the pseudo SO
effects in mesoscopic applications, e.g. pseudo spin relaxation and switching.


title: Wireless Sensor/Actuator Network Design for Mobile Control Applications

abstract:
  Wireless sensor/actuator networks (WSANs) are emerging as a new generation of
sensor networks. Serving as the backbone of control applications, WSANs will
enable an unprecedented degree of distributed and mobile control. However, the
unreliability of wireless communications and the real-time requirements of
control applications raise great challenges for WSAN design. With emphasis on
the reliability issue, this paper presents an application-level design
methodology for WSANs in mobile control applications. The solution is generic
in that it is independent of the underlying platforms, environment, control
system models, and controller design. To capture the link quality
characteristics in terms of packet loss rate, experiments are conducted on a
real WSAN system. From the experimental observations, a simple yet efficient
method is proposed to deal with unpredictable packet loss on actuator nodes.
Trace-based simulations give promising results, which demonstrate the
effectiveness of the proposed approach.


title:
On the comparison of positive elements of a C*-algebra by lower
  semicontinuous traces

abstract:
  It is shown in this paper that two positive elements of a C*-algebra agree on
all lower semicontinuous traces if and only if they are equivalent in the sense
of Cuntz and Pedersen. A similar result is also obtained in the more general
case where the two elements are comparable by their values on the lower
semicontinuous traces. This result is used to give a characterization of the
functions on the cone of lower semicontinuous traces of a stable C*-algebra
that arise from positive elements of the algebra.


title:
On a certain asymptotic relationship involving $\vartheta(t) - \lfloor t
  \rfloor$ and $t^{1/2}$

abstract:
  Let $\lfloor t \rfloor$ denote the greatest positive integer less than or
equal to a given positive real number $t$ and $\vartheta(t)$ the Chebyshev
$\vartheta$-function. In this paper, we prove a certain asymptotic relationship
involving $\vartheta(t) - \lfloor t \rfloor $ and $t^{1/2}$.


title: Comparing 2-handle additions to a genus 2 boundary component

abstract:
  We prove that knots obtained by attaching a band to a split link satisfy the
cabling conjecture. We also give new proofs that unknotting number one knots
are prime and that genus is superadditive under band sum. Additionally, we
prove a collection of results comparing two 2-handle additions to a genus two
boundary component of a compact, orientable 3-manifold. These results give a
near complete solution to a conjecture of Scharlemann and provide evidence for
a conjecture of Scharlemann and Wu. The proofs make use of a new theorem
concerning the effects of attaching a 2-handle to a suture in the boundary of a
sutured manifold.


title:
Spin-orbit effects in Na$_4$Ir$_3$O$_8$, a hyper-kagom\'{e} lattice
  antiferromagnet

abstract:
  We consider spin-orbit coupling effects in Na$_4$Ir$_3$O$_8$, a material in
which Ir$^{4+}$ spins form an hyper-kagom\'{e} lattice, a three-dimensional
network of corner-sharing triangles. We argue that both low temperature
thermodynamic measurements and the impurity susceptibility induced by dilute
substitution of Ti for Ir are suggestive of significant spin-orbit effects.
Because of uncertainties in the crystal-field parameters, we consider two
limits in which the spin-orbit coupling is either weak or strong compared to
the non-cubic atomic splittings. A semi-microscopic calculation of the exchange
Hamiltonian confirms that indeed large antisymmetric Dzyaloshinskii-Moriya (DM)
and/or symmetric exchange anisotropy may be present. In the strong spin-orbit
limit, the Ir-O-Ir superexchange contribution consists of unfrustrated strong
symmetric exchange anisotropy, and we suggest that spin-liquid behavior is
unlikely. In the weak spin-orbit limit, and for strong spin-orbit and direct
Ir-Ir exchange, the Hamiltonian consists of Heisenberg and DM interactions. The
DM coupling is parametrized by a three component DM vector (which must be
determined empirically). For a range of orientation of this vector, frustration
is relieved and an ordered state occurs. For other orientations, even the
classical ground states are very complex. We perform spin-wave and exact
diagonalization calculations which suggest the persistence of a quantum spin
liquid in the latter regime. Applications to Na$_4$Ir$_3$O$_8$ and broader
implications are discussed.


title: Ladder network as a mesoscopic switch: An exact result

abstract:
  We investigate the possibilities of a tight binding ladder network as a
mesoscopic switching device. Several cases have been discussed in which any one
or both the arms of the ladder can assume random, ordered or quasiperiodic
distribution of atomic potentials. We show that, for a special choice of the
Hamiltonian parameters it is possible to prove exactly the existence of
mobility edges in such a system, which plays a central role in the switching
action. We also present numerical results for the two-terminal conductance of a
general model of a quasiperiodically grown ladder which support the general
features of the electron states in such a network. The analysis might be
helpful in fabricating mesoscopic or DNA switching devices.


title: XMM-Newton studies of a massive cluster of galaxies: RXCJ2228.6+2036

abstract:
  We present the X-ray properties of a massive cluster of galaxies
(RXCJ2228.6+2036 at $z=0.421$) using {\it XMM-Newton} data. The X-ray mass
modeling is based on the temperature and density distributions of the
intracluster medium derived using a deprojection method. We found that
RXCJ2228.6+2036 is a hot cluster ($T_{500}=8.92^{+1.78}_{-1.32}$ keV) showing a
cooling flow rate of $12.0^{+56.0}_{-12.0}$ M$_{\odot}$yr$^{-1}$ based on
spectral fitting within the cooling flow radius ($r_{cool}=147\pm10$ kpc). The
total cluster mass is $M_{500}=(1.19\pm0.35)\times10^{15}$ M$_{\odot}$ and the
mean gas mass fraction is $f_{gas}=0.165\pm0.045$ at $r_{500}=1.61\pm0.16$ Mpc.
We discussed the PSF-correction effect on the spectral analysis and found that
for the annular width we chose the PSF-corrected temperatures are consistent
with those without PSF-correction. We observed a remarkable agreement between
X-ray and SZ results, which is of prime importance for the future SZ survey.
RXCJ2228.6+2036 obeys the empirical scaling relations found in general massive
galaxy clusters (e.g. $S$--$T$, $M$--$T$, $L$--$T$ and $M$--$Y$) after
accounting for self-similar evolution.


title: Tunable 0.7 conductance plateau in quantum dots

abstract:
  A consistent approach in forming the 0.7 structure by using a quantum dot
rather than a quantum point contact is demonstrated. With this scheme, it was
possible to tune on and off the 0.7 structure. The 0.7 structure continuously
evolved into a normal integer conductance plateau by varying the tuning
condition. Unlike the conventional 0.7 plateau, the new 0.7 structure was
observed even at low electron temperatures down to 100 mK, with unprecedented
flatness. From our results, it is concluded that electron interference should
be taken into consideration to explain the 0.7 structure.


title:
Co-ordinate Interleaved Distributed Space-Time Coding for
  Two-Antenna-Relays Networks

abstract:
  Distributed space time coding for wireless relay networks when the source,
the destination and the relays have multiple antennas have been studied by Jing
and Hassibi. In this set-up, the transmit and the receive signals at different
antennas of the same relay are processed and designed independently, even
though the antennas are colocated. In this paper, a wireless relay network with
single antenna at the source and the destination and two antennas at each of
the R relays is considered. A new class of distributed space time block codes
called Co-ordinate Interleaved Distributed Space-Time Codes (CIDSTC) are
introduced where, in the first phase, the source transmits a T-length complex
vector to all the relays and in the second phase, at each relay, the in-phase
and quadrature component vectors of the received complex vectors at the two
antennas are interleaved and processed before forwarding them to the
destination. Compared to the scheme proposed by Jing-Hassibi, for $T \geq 4R$,
while providing the same asymptotic diversity order of 2R, CIDSTC scheme is
shown to provide asymptotic coding gain with the cost of negligible increase in
the processing complexity at the relays. However, for moderate and large values
of P, CIDSTC scheme is shown to provide more diversity than that of the scheme
proposed by Jing-Hassibi. CIDSTCs are shown to be fully diverse provided the
information symbols take value from an appropriate multi-dimensional signal
set.


title: SiZer for Censored Density and Hazard Estimation

abstract:
  The SiZer method is extended to nonparametric hazard estimation and also to
censored density and hazard estimation. The new method allows quick, visual
statistical inference about the important issue of statistically significant
increases and decreases in the smooth curve estimate. This extension has
required the opening of a new avenue of research on the interface between
statistical inference and scale space.


title: On a six-parameter generalized Burr XII distribution

abstract:
  In this paper, we derive a probability density function that generalizes the
Burr XII distribution. The cumulative distribution function and the $n^{th}$
moment of the generalized distribution are obtained while the distribution of
some order statistics of the distribution are established. A theorem that
relate the new distribution to another statistical distribution is established.


title: On type III generalized half logistic distribution

abstract:
  It is well known that generalized models is attracting the attention of
researchers in recent times because of their flexibilities. Particularly, the
logistic model has been generalized and applied by many authors while the half
logistic distribution has not recieve much attention in term of its
generalization. In this paper, we considered a generalized form of half
logistic model called type III generalized half logistic distribution. We
obtained its probability density function, the cumulative distribution
function, the $n^{th}$ moment, the median, the mode, the 100$p$-percentage
points and the order statistics of the generalized distribution are
established.


title:
Interplay between strong correlations and magnetic field in the
  symmetric periodic Anderson model

abstract:
  Magnetic field effects in Kondo insulators are studied theoretically, using a
local moment approach to the periodic Anderson model within the framework of
dynamical mean-field theory. Our main focus is on field-induced changes in
single-particle dynamics and the associated hybridization gap in the density of
states. Particular emphasis is given to the strongly correlated regime, where
dynamics are found to exhibit universal scaling in terms of a field-dependent
low energy coherence scale. Although the bare applied field is globally
uniform, the effective fields experienced by the conduction electrons and the
$f$-electrons differ because of correlation effects. A continuous
insulator-metal transition is found to occur on increasing the applied field,
closure of the hybridization gap reflecting competition between Zeeman
splitting and screening of the $f$-electron local moments. For intermediate
interaction strengths the hybridization gap depends non-linearly on the applied
field, while in strong coupling its field dependence is found to be linear. For
the classic Kondo insulator YbB$_{12}$, good agreement is found upon direct
comparison of the field evolution of the experimental transport gap with the
theoretical hybridization gap in the density of states.


title:
A method for atomistic spin dynamics simulations: implementation and
  examples

abstract:
  We present a method for performing atomistic spin dynamic simulations. A
comprehensive summary of all pertinent details for performing the simulations
such as equations of motions, models for including temperature, methods of
extracting data and numerical schemes for performing the simulations is given.
The method can be applied in a first principles mode, where all interatomic
exchange is calculated self-consistently, or it can be applied with frozen
parameters estimated from experiments or calculated for a fixed
spin-configuration. Areas of potential applications to different magnetic
questions are also discussed. The method is finally applied to one situation
where the macrospin model breaks down; magnetic switching in ultra strong
fields.


title: Charged-Rotating Black Holes in Higher-dimensional (A)DS-Gravity

abstract:
  We present numerical evidences for the existence of rotating black hole
solutions in d-dimensional Einstein-Maxwell theory with a cosmological constant
and for $d$ odd. The metric used possesses $(d+1)/2$ Killing vectors and the
solutions have $(d-1)/2$ equal angular momenta. A Schwarschild-type coordinate
is used for the radial variable and both signs of the cosmological constant are
emphasized. Several properties of the solutions are studied, namely their
surface gravity, mass and angular momentum as functions of two parameters: the
magnetic field and the angular velocity at the horizon. The influence of the
electromagnetic field on the domain of existence of the black holes is studied
are compared to the vacuum case where analytic solutions are available.


title:
Distinguished principal series representations for GLn over a p-adic
  field

abstract:
  In the following article, we give a description of the distingushed
irreducible principal series representations of the general linear group over a
p-adic field in terms of inducing datum. This provides a counter-example to a
conjecture of Jacquet about distinction (Conjecture 1 in U.K Anandavardhanan,
"Distinguished non-Archimedean representations ", Proc. Hyderabad Conference on
Algebra and Number Theory, 2005, 183-192).


title: On the quantization of polygon spaces

abstract:
  Moduli spaces of polygons have been studied since the nineties for their
topological and symplectic properties. Under generic assumptions, these are
symplectic manifolds with natural global action-angle coordinates. This paper
is concerned with the quantization of these manifolds and of their action
coordinates. Applying the geometric quantization procedure, one is lead to
consider invariant subspaces of a tensor product of irreducible representations
of SU(2). These quantum spaces admit natural sets of commuting observables. We
prove that these operators form a semi-classical integrable system, in the
sense that they are Toeplitz operators with principal symbol the square of the
action coordinates. As a consequence, the quantum spaces admit bases whose
vectors concentrate on the Lagrangian submanifolds of constant action. The
coefficients of the change of basis matrices can be estimated in terms of
geometric quantities. We recover this way the already known asymptotics of the
classical 6j-symbols.


title: X-ray Linear Dichroism in cubic compounds: the case of Cr3+ in MgAl2O4

abstract:
  The angular dependence (x-ray linear dichroism) of the Cr K pre-edge in
MgAl2O4:Cr3+ spinel is measured by means of x-ray absorption near edge
structure spectroscopy (XANES) and compared to calculations based on density
functional theory (DFT) and ligand field multiplet theory (LFM). We also
present an efficient method, based on symmetry considerations, to compute the
dichroism of the cubic crystal starting from the dichroism of a single
substitutional site. DFT shows that the electric dipole transitions do not
contribute to the features visible in the pre-edge and provides a clear vision
of the assignment of the 1s-->3d transitions. However, DFT is unable to
reproduce quantitatively the angular dependence of the pre-edge, which is, on
the other side, well reproduced by LFM calculations. The most relevant factors
determining the dichroism of Cr K pre-edge are identified as the site
distortion and 3d-3d electronic repulsion. From this combined DFT, LFM approach
is concluded that when the pre-edge features are more intense than 4 % of the
edge jump, pure quadrupole transitions cannot explain alone the origin of the
pre-edge. Finally, the shape of the dichroic signal is more sensitive than the
isotropic spectrum to the trigonal distortion of the substitutional site. This
suggests the possibility to obtain quantitative information on site distortion
from the x-ray linear dichroism by performing angular dependent measurements on
single crystals.


title:
Fixed points in models of continuous opinion dynamics under bounded
  confidence

abstract:
  We present two models of continuous opinion dynamics under bounded confidence
which are representable as nonnegative discrete dynamical systems, namely the
Hegselmann-Krause model (Hegselmann and Krause, Journal of Artificial Societies
and Social Simulation 5(3), 2002) and the Deffuant-Weisbuch model (Deffuant et
al, Advances in Complex Systems, 3, 2000). We fully characterize the set of
fixed points for both models. They are identical. Further on, we present
reformulations of both models on the more general level of densities of agents
in the opinion space as interactive Markov chains. We also characterize the
sets of fixed points as identical in both models.


title:
Spin-S Kitaev model: Classical Ground States, Order by Disorder and
  Exact Correlation Functions

abstract:
  In the first part of this paper, we study the spin-S Kitaev model using spin
wave theory. We discover a remarkable geometry of the minimum energy surface in
the N-spin space. The classical ground states, called Cartesian or CN-ground
states, whose number grows exponentially with the number of spins N, form a set
of points in the N-spin space. These points are connected by a network of flat
valleys in the N-spin space, giving rise to a continuous family of classical
ground states. Further, the CN-ground states have a correspondence with dimer
coverings and with self avoiding walks on a honeycomb lattice. The zero point
energy of our spin wave theory picks out a subset from a continuous family of
classically degenerate states as the quantum ground states; the number of these
states also grows exponentially with N. In the second part, we present some
exact results. For arbitrary spin-S, we show that localized Z_2 flux
excitations are present by constructing plaquette operators with eigenvalues
\pm 1 which commute with the Hamiltonian. This set of commuting plaquette
operators leads to an exact vanishing of the spin-spin correlation functions,
beyond nearest neighbor separation, found earlier for the spin-1/2 model [G.
Baskaran, S. Mandal and R. Shankar, Phys. Rev. Lett. 98, 247201 (2007)]. We
introduce a generalized Jordan-Wigner transformation for the case of general
spin-S, and find a complete set of commuting link operators, similar to the
spin-1/2 model, thereby making the Z_2 gauge structure more manifest. The
Jordan-Wigner construction also leads, in a natural fashion, to Majorana
fermion operators for half-integer spin cases and hard-core boson operators for
integer spin cases, strongly suggesting the presence of Majorana fermion and
boson excitations in the respective low energy sectors.


title: Optical Spectropolarimetry and Asphericity of Type Ic SN 2007gr

abstract:
  We present optical spectropolarimetric observations of Type Ic supernova (SN)
2007gr with Subaru telescope at 21 days after the maximum brightness (~37 days
after the explosion). Non-zero polarization as high as ~3% is observed at the
absorption feature of Ca II IR triplet. The polarization of the continuum light
is ~0.5% if we estimate the interstellar polarization (ISP) component assuming
that the continuum polarization has a single polarization angle. This suggests
that the axis ratio of the SN photosphere projected to the sky is different
from unity by ~10%. The polarization angle at the Ca II absorption is almost
aligned to that of the continuum light. These features may be understood by the
model where a bipolar explosion with an oblate photosphere is viewed from the
slightly off-axis direction and explosively synthesized Ca near the polar
region obscures the light originated around the minor axis of the SN
photosphere. Given the uncertainty of the ISP, however, the polarization data
could also be interpreted by the model with an almost spherically symmetric
photosphere and a clumpy Ca II distribution.


title:
Multi-Dimensional Simulations of Radiative Transfer in Aspherical
  Core-Collapse Supernovae

abstract:
  We study optical radiation of aspherical supernovae (SNe) and present an
approach to verify the asphericity of SNe with optical observations of
extragalactic SNe. For this purpose, we have developed a multi-dimensional
Monte-Carlo radiative transfer code, SAMURAI (SupernovA MUlti-dimensional
RAdIative transfer code). The code can compute the optical light curve and
spectra both at early phases (<~ 40 days after the explosion) and late phases
(~ 1 year after the explosion), based on hydrodynamic and nucleosynthetic
models. We show that all the optical observations of SN 1998bw (associated with
GRB 980425) are consistent with polar-viewed radiation of the aspherical
explosion model with kinetic energy 20 x 10^{51} ergs. Properties of off-axis
hypernovae are also discussed briefly.


title: Resolving Super Massive Black Holes with LISA

abstract:
  We study the angular resolution of the gravitational wave detector LISA and
show that numerical relativity can drastically improve the accuracy of position
location for coalescing Super Massive Black Hole (SMBH) binaries. For systems
with total redshifted mass above $10^7 M_{\odot}$, LISA will mainly see the
merger and ring-down of the gravitational wave (GW) signal, which can now be
computed numerically using the full Einstein equations. Using numerical
waveforms that also include about ten GW cycles of inspiral, we improve
inspiral-only position estimates by an order of magnitude. We show that LISA
localizes half of all such systems at $z=1$ to better than 3 arcminutes and the
best 20% to within one arcminute. This will give excellent prospects for
identifying the host galaxy.


title:
Modified kagome physics in the natural spin-1/2 kagome lattice systems -
  kapellasite Cu3Zn(OH)6Cl2 and haydeeite Cu3Mg(OH)6Cl2

abstract:
  The recently discovered natural minerals Cu3Zn(OH)6Cl2 and Cu3Mg(OH)6Cl2 are
spin 1/2 systems with an ideal kagome geometry. Based on electronic structure
calculations, we develop a realistic model which includes couplings across the
kagome hexagons beyond the original kagome model that are intrinsic in real
kagome materials. Exact diagonalization studies for the derived model reveal a
strong impact of these couplings on the magnetic ground state. Our predictions
could be compared to and supplied with neutron scattering, thermodynamic and
NMR data.


title:
Functional minimization method addressed to the vacuum finding for an
  arbitrary driven quantum oscillator

abstract:
  The old problem exists for a driven (time-dependent) quantum oscillator: to
differ the true vacuum state from the squeezed one. We suggest finding the true
vacuum state by minimization of the functional containing the difference of the
potential and kinetic energies of oscillator. Analytical and numerical examples
confirming this offer are considered.


title:
Experimental evidence of non-Amontons behaviour at a multicontact
  interface

abstract:
  We report on normal stress field measurements at the multicontact interface
between a rough elastomeric film and a smooth glass sphere under normal load,
using an original MEMS-based stress sensing device. These measurements are
compared to Finite Elements Method calculations with boundary conditions
obeying locally Amontons' rigid-plastic-like friction law with a uniform
friction coefficient. In dry contact conditions, significant deviations are
observed which decrease with increasing load. In lubricated conditions, the
measured profile recovers almost perfectly the predicted profile. These results
are interpreted as a consequence of the finite compliance of the multicontact
interface, a mechanism which is not taken into account in Amontons' law.


title: Beating of Aharonov-Bohm oscillations in a closed-loop interferometer

abstract:
  One of the points at issue with closed-loop-type interferometers is beating
in the Aharonov-Bohm (AB) oscillations. Recent observations suggest the
possibility that the beating results from the Berry-phase pickup by the
conducting electrons in materials with the strong spin-orbit interaction (SOI).
In this study, we also observed beats in the AB oscillations in a gate-defined
closed-loop interferometer fabricated on a GaAs/AlGaAs two-dimensional
electron-gas heterostructure. Since this heterostructure has very small SOI,
the picture of the Berry-phase pickup is ruled out. The observation of beats in
this study, with the controllability of forming a single transverse subband
mode in both arms of our gate-defined interferometer, also rules out the
often-claimed multiple transverse subband effect. It is observed that nodes of
the beats with an h/2e period exhibit a parabolic distribution for varying the
side gate. These results are shown to be well interpreted, without resorting to
the SOI effect, by the existence of two-dimensional multiple longitudinal modes
in a single transverse subband. The Fourier spectrum of measured conductance,
despite showing multiple h/e peaks with the magnetic-field dependence that are
very similar to that from strong-SOI materials, can also be interpreted as the
two-dimensional multiple-longitudinal-modes effect.


title:
A few equalities involving integrals of the logarithm of the Riemann
  Zeta-function and equivalent to the Riemann hypothesis

abstract:
  Using a generalized Littlewood theorem concerning integrals of the logarithm
of analytical functions, we have established a few equalities involving
integrals of the logarithm of the Riemann Zeta-function and have rigorously
proven that they are equivalent to the Riemann hypothesis. Separate
consideration for imaginary and real parts of these equalities, which deal
correspondingly with the integrals of the logarithm of the module of the
Riemann function and with the integrals of its argument is given. Preliminary
results of the numerical research performed using these equalities to test the
Riemann hypothesis are presented.


title: Shock Waves in Plane Symmetric Spacetimes

abstract:
  We consider Einstein's equations coupled to the Euler equations in plane
symmetry, with compact spatial slices and constant mean curvature time. We show
that for a wide variety of equations of state and a large class of initial
data, classical solutions break down in finite time. The key mathematical
result is a new theorem on the breakdown of solutions of systems of balance
laws. We also show that an extension of the solution is possible if the spatial
derivatives of the energy density and the velocity are bounded, indicating that
the breakdown is really due to the formation of shock waves.


title: A positive solution to a conjecture of A. Katok for diffeomorphism case

abstract:
  In this paper, using Pesin theory and Liao theory, we give a positive
solution to a conjecture of A. Katok.


title:
Magnetic order in double-layer manganites (La(1-z)Pr(z))1.2Sr1.8Mn2O7:
  intrinsic properties and role of the intergrowths

abstract:
  We report on an investigation of the double-layer manganite series
(La(1-z)Pr(z))1.2Sr1.8Mn2O7 (0 <= z <= 1), carried out on single crystals by
means of both macroscopic magnetometry and local probes of magnetism (muSR,
55Mn NMR). Muons and NMR demonstrate an antiferromagnetically ordered ground
state at non-ferromagnetic compositions (z >= 0.6), while more moderate Pr
substitutions (0.2 <= z <= 0.4) induce a spin reorientation transition within
the ferromagnetic phase.
  A large magnetic susceptibility is detected at {Tc,TN} < T < 250K at all
compositions. From 55Mn NMR spectroscopy, such a response is unambiguously
assigned to the intergrowth of a ferromagnetic pseudocubic phase
(La(1-z)Pr(z))(1-x)Sr(x)MnO3, with an overall volume fraction estimated as
0.5-0.7% from magnetometry. Evidence is provided for the coupling of the
magnetic moments of these inclusions with the magnetic moments of the
surrounding (La(1-z)Pr(z))1.2Sr1.8Mn2O7 phase, as in the case of finely
dispersed impurities. We argue that the ubiquitous intergrowth phase may play a
role in the marked first-order character of the magnetic transition and the
metamagnetic properties above Tc reported for double-layer manganites.


title: A Tamed 3D Navier-Stokes Equation in Domains

abstract:
  In this paper, we analyze a tamed 3D Navier-Stokes equation in uniform
$C^2$-domains (not necessarily bounded), which obeys the scaling invariance
principle, and prove the existence and uniqueness of strong solutions to this
tamed equation. In particular, if there exists a bounded solution to the
classical 3D Navier-Stokes equation, then this solution satisfies our tamed
equation. Moreover, the existence of a global attractor for the tamed equation
in bounded domains is also proved. As simple applications, some well known
results for the classical Navier-Stokes equations in unbounded domains are
covered.


title:
The analysis of reactions $\pi N\to two mesons + N$ within reggeon
  exchanges. 1. Fit and results

abstract:
  The novel point of this analysis is a direct use of reggeon exchange
technique for the description of the reactions $\pi N\to two mesons + N$ at
large energies of the initial pion. This approach allows us to describe
simultaneously distributions over $M$ (invariant mass of two mesons) and $t$
(momentum transfer squared to nucleons). Making use of this technique, the
following resonances (as well as corresponding bare states), produced in the
$\pi N\to \pi^0\pi^0 N$ reaction are studied: $f_0(980)$, $f_0(1300)$,
$f_0(1200-1600)$, $f_0(1500)$, $f_0(1750)$, $f_2(1270)$, $f_2(1525)$,
$f_2(1565)$, $f_2(2020)$, $f_4(2025)$. Adding data for the reactions $p\bar
p({\rm at rest, from liquid H_2})\to \pi^0\pi^0\pi^0$, $\pi^0\pi^0\eta$,
$\pi^0\eta\eta$ and $p\bar p({\rm at rest, from gaseous H_2})\to
\pi^0\pi^0\pi^0$, $\pi^0\pi^0\eta$, $\pi^0\eta\eta$, we have performed
simultaneous $K$-matrix fits of two-meson spectra in all these reactions. The
results of combined fits to the above-listed isoscalar $f_J$-states and to
isovector ones, $a_0(980)$, $a_0(1475)$, $a_2(1320)$, are presented.


title:
The injectivity of the global function of a cellular automaton in the
  hyperbolic plane is undecidable

abstract:
  In this paper, we look at the following question. We consider cellular
automata in the hyperbolic plane and we consider the global function defined on
all possible configurations. Is the injectivity of this function undecidable?
The problem was answered positively in the case of the Euclidean plane by
Jarkko Kari, in 1994. In the present paper, we show that the answer is also
positive for the hyperbolic plane: the problem is undecidable.


title:
Universal tree structures in directed polymers and models of evolving
  populations

abstract:
  By measuring or calculating coalescence times for several models of
coalescence or evolution, with and without selection, we show that the ratios
of these coalescence times become universal in the large size limit and we
identify a few universality classes.


title:
Exact degenerate ground states for the F-AF spin chain with bond
  alternation

abstract:
  We investigate the $J_1$-$J_2$ spin chain consisting of spins with magnitude
$\frac12$. The nearest-neighbor and the next-nearest-neighbor exchange
interactions are ferromagnetic and antiferromagnetic, respectively, and induce
strong frustration. Both these interactions involve the bond alternation. We
find exact solutions for all the degenerate ground states on the phase boundary
of the ferromagnetic phase. The degeneracy remains irrespective of two
parameters representing the bond alternation. The exact solutions are of closed
forms for no bond alternation and of recursion formulae in general. The exact
solutions are applicable to the $\Delta$ chain as a special case.


title: Micro-crystalline inclusions analysis by PIXE and RBS

abstract:
  A characteristic feature of the nuclear microprobe using a 3 MeV proton beam
is the long range of particles (around 70 \mu m in light matrices). The PIXE
method, with EDS analysis and using the multilayer approach for treating the
X-ray spectrum allows the chemistry of an intra-crystalline inclusion to be
measured, provided the inclusion roof and thickness at the impact point of the
beam (Z and e, respectively) are known (the depth of the inclusion floor is Z +
e). The parameter Z of an inclusion in a mineral can be measured with a
precision of around 1 \mu m using a motorized microscope. However, this value
may significantly depart from Z if the analyzed inclusion has a complex shape.
The parameter e can hardly be measured optically. By using combined RBS and
PIXE measurements, it is possible to obtain the geometrical information needed
for quantitative elemental analysis. This paper will present measurements on
synthetic samples to investigate the advantages of the technique, and also on
natural solid and fluid inclusions in quartz. The influence of the geometrical
parameters will be discussed with regard to the concentration determination by
PIXE. In particular, accuracy of monazite micro-inclusion dating by coupled
PIXE-RBS will be presented.


title: Non-secret correlations can be used to distribute secrecy

abstract:
  A counter-intuitive result in entanglement theory was shown in [PRL 91 037902
(2003)], namely that entanglement can be distributed by sending a separable
state through a quantum channel. In this work, following an analogy between the
entanglement and secret key distillation scenarios, we derive its classical
analog: secrecy can be distributed by sending non-secret correlations through a
private channel. This strengthens the close relation between entanglement and
secrecy.


title: Ising magnetism and ferroelectricity in Ca$_3$CoMnO$_6$

abstract:
  The origin of both the Ising chain magnetism and ferroelectricity in
Ca$_3$CoMnO$_6$ is studied by $ab$ $initio$ electronic structure calculations
and x-ray absorption spectroscopy. We find that Ca$_3$CoMnO$_6$ has the
alternate trigonal prismatic Co$^{2+}$ and octahedral Mn$^{4+}$ sites in the
spin chain. Both the Co$^{2+}$ and Mn$^{4+}$ are in the high spin state. In
addition, the Co$^{2+}$ has a huge orbital moment of 1.7 $\mu_B$ which is
responsible for the significant Ising magnetism. The centrosymmetric crystal
structure known so far is calculated to be unstable with respect to exchange
striction in the experimentally observed $\uparrow\uparrow\downarrow\downarrow$
antiferromagnetic structure for the Ising chain. The calculated inequivalence
of the Co-Mn distances accounts for the ferroelectricity.


title: Alpha effect and diffusivity in helical turbulence with shear

abstract:
  We study the dependence of turbulent transport coefficients, such as the
components of the $\alpha$ tensor ($\alpha_{ij}$) and the turbulent magnetic
diffusivity tensor ($\eta_{ij}$), on shear and magnetic Reynolds number in the
presence of helical forcing. We use three-dimensional direct numerical
simulations with periodic boundary conditions and measure the turbulent
transport coefficients using the kinematic test field method. In all cases the
magnetic Prandtl number is taken as unity. We find that with increasing shear
the diagonal components of $\alpha_{ij}$ quench, whereas those of $\eta_{ij}$
increase. The antisymmetric parts of both tensors increase with increasing
shear. We also propose a simple expression for the turbulent pumping velocity
(or $\gamma$ effect). This pumping velocity is proportional to the kinetic
helicity of the turbulence and the vorticity of the mean flow. For negative
helicity, i.e. for a positive trace of $\alpha_{ij}$, it points in the
direction of the mean vorticity, i.e. perpendicular to the plane of the shear
flow. Our simulations support this expression for low shear and magnetic
Reynolds number. The transport coefficients depend on the wavenumber of the
mean flow in a Lorentzian fashion, just as for non-shearing turbulence.


title: Thermal contact resistance between two nanoparticles

abstract:
  We compute the thermal conductance between two nanoparticles in contact based
on the Molecular Dynamics technique. The contact is generated by letting both
particles stick together under van der Waals attractions. The thermal
conductance is derived from the fluctuation-dissipation theorem and the time
fluctuations of the exchanged power. We show that the conductance is
proportional to the atoms involved in the thermal interaction. In the case of
silica, the atomic contribution to the thermal conductance is in the range of
0.5 to 3 nW.K-1. This result fits to theoretical predictions based on
characteristic times of the temperature fluctuation. The order of magnitude of
the contact conductance is 1 \mu W.K-1 when the cross section ranges from 1 to
10nm2.