title:
Asymptotic Analysis of General Multiuser Detectors in MIMO DS-CDMA
  Channels

abstract:
  We analyze a MIMO DS-CDMA channel with a general multiuser detector including
a nonlinear multiuser detector, using the replica method. In the many-user,
limit the MIMO DS-CDMA channel with the multiuser detector is decoupled into a
bank of single-user SIMO Gaussian channels if a spatial spreading scheme is
employed. On the other hand, it is decoupled into a bank of single-user MIMO
Gaussian channels if a spatial spreading scheme is not employed. The spectral
efficiency of the MIMO DS-CDMA channel with the spatial spreading scheme is
comparable with that of the MIMO DS-CDMA channel using an optimal space-time
block code without the spatial spreading scheme. In the case of the QPSK data
modulation scheme the spectral efficiency of the MIMO DS-CDMA channel with the
MMSE detector shows {\it waterfall} behavior and is very close to the
corresponding sum capacity when the system load is just below the transition
point of the {\it waterfall} behavior. Our result implies that the performance
of a multiuser detector taking the data modulation scheme into consideration
can be far superior to that of linear multiuser detectors.


title:
Comment to the article "Possible Systematic Effects in Fomblin Coated
  Storage Cell Neutron Lifetime Measurements", Steve K. Lamoreaux [1]

abstract:
  The author of article discusses the possible systematic effects in our
experiment using reference and picture from allegedly our publication. First of
all this publication does not exist. The assumption of author about the
probability of lower energy upscattering is in a rough contradiction (300
times) with our experimental limit which is extremely lower, about 6x10-9 per
neutron collision. The second assumption of author concerning quasi-stable
orbits of UCN with higher energy due to specular neutron reflection from trap
wall is also in a rough contradiction with our experimental data clear
demonstrated in our previous articles as well in the last very detailed article
recently presented in the arXiv.
  We are very surprised that author discusses well known questions studied in
our experiment in details.


title: Switching of the vortex polarity in a magnetic nanodisk by a DC current

abstract:
  We study the dynamics of a vortex state nanodisk due to a dc spin current,
perpendicular to the disk plane. The irreversible switching of the vortex
polarity takes place above some threshold current. The detailed description of
these processes is obtained by spin-lattice simulations.


title:
Sine-Gordon solitons, auxiliary fields, and singular limit of a double
  pendulums chain

abstract:
  We consider the continuum version of an elastic chain supporting topological
and non-topological degrees of freedom; this generalizes a model for the
dynamics of DNA recently proposed and investigated by ourselves. In a certain
limit, the non-topological degrees of freedom are frozen, and the model reduces
to the sine-Gordon equations and thus supports well-known topological soliton
solutions. We consider a (singular) perturbative expansion around this limit
and study in particular how the non-topological field assume the role of an
auxiliary field. This provides a more general framework for the slaving of this
degree of freedom on the topological one, already observed elsewhere in the
context of the mentioned DNA model; in this framework one expects such
phenomenon to arise in a quite large class of field-theoretical models.


title: NGC4438 and its environment at radio wavelengths

abstract:
  We present multi-frequency, radio-continuum and HI observations of NGC4438,
the highly-disturbed, active galaxy in the Virgo cluster, with the VLA and the
GMRT. High-resolution observations with the VLA at 4860 and 8460 MHz show the
presence of an inverted-spectrum radio nucleus located between the highly
asymmetric lobes of radio emission. This demonstrates that these lobes arise
due to an AGN rather than a compact nuclear starburst. The low-frequency radio
continuum observations made with the GMRT detect the extended emission on the
western side of the galaxy whose spectral index is flatter at higher
frequencies and suggests that it is a mixture of thermal and non-thermal
emission.
  The HI observations show an elongated structure which is displaced by ~4.1
kpc on the western side of NGC4438 and has a size of ~9.8 kpc and a mass of
1.8*10^8 M_sun. The velocity field suggests systematic rotation. We also detect
HI emission from the disk of the galaxy with a mass of 1.2*10^8 M_sun. We
detect a faint HI tail towards the north of NGC4438 close to a stellar tail
seen in deep optical observations. This HI tail has a total extent of ~50 kpc
and a mass of 1.4*10^8 M_sun if it is at the distance of NGC4438. The velocity
of the HI tail is ~-10 km/s similar to that of HI emission from IC 3355, but
the possibility that the tail could be foreground Galactic emission cannot be
ruled out. We discuss the different structures in the light of different
models.


title:
Unveiling new systematics in the self-assembly of atomic chains on
  Si(111)

abstract:
  Self-assembled arrays of atomic chains on Si(111) represent a fascinating
family of nanostructures with quasi-one-dimensional electronic properties.
These surface reconstructions are stabilized by a variety of adsorbates ranging
from alkali and alkaline earth metals to noble and rare earth metals. Combining
the complementary strength of dynamical low-energy electron diffraction,
scanning tunneling microscopy and angle-resolved photoemission spectroscopy, we
recently showed that besides monovalent and divalent adsorbates, trivalent
adsorbates are also able to stabilize silicon honeycomb chains. Consequently
silicon honeycomb chains emerge as a most stable, universal building block
shared by many atomic chain structures. We here present the systematics behind
the self-assembly mechanism of these chain systems and relate the valence state
of the adsorbate to the accessible symmetries of the chains.


title: Properties of noncommutative axionic electrodynamics

abstract:
  Using the gauge-invariant but path-dependent variables formalism, we compute
the static quantum potential for noncommutative axionic electrodynamics, and
find a radically different result than the corresponding commutative case. We
explicitly show that the static potential profile is analogous to that
encountered in both non-Abelian axionic electrodynamics and in Yang-Mills
theory with spontaneous symmetry breaking of scale symmetry.


title: Role of homeostasis in learning sparse representations

abstract:
  Neurons in the input layer of primary visual cortex in primates develop
edge-like receptive fields. One approach to understanding the emergence of this
response is to state that neural activity has to efficiently represent sensory
data with respect to the statistics of natural scenes. Furthermore, it is
believed that such an efficient coding is achieved using a competition across
neurons so as to generate a sparse representation, that is, where a relatively
small number of neurons are simultaneously active. Indeed, different models of
sparse coding, coupled with Hebbian learning and homeostasis, have been
proposed that successfully match the observed emergent response. However, the
specific role of homeostasis in learning such sparse representations is still
largely unknown. By quantitatively assessing the efficiency of the neural
representation during learning, we derive a cooperative homeostasis mechanism
that optimally tunes the competition between neurons within the sparse coding
algorithm. We apply this homeostasis while learning small patches taken from
natural images and compare its efficiency with state-of-the-art algorithms.
Results show that while different sparse coding algorithms give similar coding
results, the homeostasis provides an optimal balance for the representation of
natural images within the population of neurons. Competition in sparse coding
is optimized when it is fair. By contributing to optimizing statistical
competition across neurons, homeostasis is crucial in providing a more
efficient solution to the emergence of independent components.


title:
Representing a product system representation as a contractive semigroup
  and applications to regular isometric dilations

abstract:
  In this paper we propose a new technical tool for analyzing representations
of Hilbert $C^*$-product systems. Using this tool, we give a new proof that
every doubly commuting representation over $\mathbb{N}^k$ has a regular
isometric dilation, and we also prove sufficient conditions for the existence
of a regular isometric dilation of representations over more general
subsemigroups of $\mathbb{R}_+^k$.


title: Supernova remnants with magnetars: clues to magnetar formation

abstract:
  I discuss the lack of observational evidence that magnetars are formed as
rapidly rotating neutron stars. Supernova remnants containing magnetars do not
show the excess of kinetic energy expected for such a formation scenario, nor
is there any evidence for a relic pulsar wind nebula. However, it could be that
magnetars are formed with somewhat slower rotation periods, or that not all
excess rotational energy was used to boost the explosion energy, for example as
a result of gravitational radiation. Another observational tests for the rapid
initial period hypothesis is to look for statistical evidence that about 1% of
the observed supernovae have an additional 1E40-1E44 erg/s excess energy during
the first year, caused by the spin down luminosity of a magnetar. An
alternative scenario for the high magnetic fields of magnetars is the fossil
field hypothesis, in which the magnetic field is inherited from the progenitor
star. Direct observational tests for this hypothesis are harder to formulate,
unless the neutron star formed in the SN1987A explosion emerges as a slowly
rotating magnetar. Finally, I point out the possible connection between the
jets in Cas A and its X-ray point source: the jets in Cas A may indicate that
the explosion was accompanied by an X-ray flash, probably powered by a rapidly
rotating compact object. However, the point source in Cas A does not seem to be
a rapidly rotating neutron star, suggesting that the neutron star has slowed
down considerably in 330 yr, requiring a magnetar-like field.


title: The Emerging Features of Bipolar Magnetic Regions during Solar Minima

abstract:
  Solar magnetic synoptic charts obtained by NSO/Kitt Peak and SOHO/MDI are
analyzed for studying the appearance of bipolar magnetic regions (BMRs) during
solar minima. As a result, we find the emergence of long-lived BMRs has three
typical features. (1) BMRs' emerging rates of the new cycles increase about 3
times faster than those of the old cycles decrease. (2) Two consecutive solar
cycles have an overlapping period of near 10 Carrington rotations. During this
very short overlapping time interval, BMRs of two cycles tend to concentrate in
the same longitudes. (3) About 53% BMRs distribute with a longitudinal distance
of 1/8 solar rotation. Such phenomenon suggests a longitudinal mode of m=8
existing during solar minima.


title:
Simulation of the Single- and Double-Slit Experiments with Quantum
  Walkers

abstract:
  We employ the broken-link model to create a barrier with slits in a
two-dimensional lattice. The diffraction and interference patterns of the
probability distribution of quantum walkers passing through the slits are
analyzed. Simulations were performed using the main types of coins, and display
diffraction and interference patterns that depend on the choice of coins.


title:
Flux Densities and Radio Polarization Characteristics of Two Vela-like
  Pulsars

abstract:
  We report on dual-frequency radio polarimetry observations of two young,
energetic pulsars, PSRs J0940-5428 and J1301-6305. These were among the first
Vela-like pulsars discovered in the Parkes Multibeam survey. We conducted
observations of these pulsars with the Australia Telescope Compact Array (ATCA)
at center frequencies of 1384 and 2496 MHz using pulsar gating while preserving
full Stokes parameters. After correcting for bandwidth depolarization, we have
measured polarization characteristics, flux densities, and rotation measures
for these pulsars. The spectral indices derived from the ATCA data are shallow
but still consistent with values seen for pulsars of this type. The rotation
measures for both pulsars are consistent with those reported recently using
data from the Parkes telescope, and both pulsars have highly linearly polarized
pulse profiles at both 1384 and 2496 MHz. Our results support a previously
noted correlation between high degree of linear polarization, shallow spectral
index, and large spin-down luminosity.


title: Entanglement Production in Non-Equilibrium Thermodynamics

abstract:
  We define and analyse the concept of entanglement production during the
evolution of a general quantum mechanical dissipative system. While it is
important to minimise entropy production in order to achieve thermodynamical
efficiency, maximising the rate of change of entanglement is important in
quantum information processing. Quantitative relations are obtained between
entropy and entanglement productions, under specific assumptions detailed in
the text. We apply these to the processes of dephasing and decay of
correlations between two initially entangled qubits. Both the Master equation
treatment as well as the higher Hilbert space analysis are presented. Our
formalism is very general and contains as special cases many reported
individual instance of entanglement dynamics, such as, for example, the
recently discovered notion of the sudden death of entanglement.


title: Late-time behaviour of the tilted Bianchi type VI$_{-1/9}$ models

abstract:
  We study tilted perfect fluid cosmological models with a constant equation of
state parameter in spatially homogeneous models of Bianchi type VI$_{-1/9}$
using dynamical systems methods and numerical simulations. We study models with
and without vorticity, with an emphasis on their future asymptotic evolution.
We show that for models with vorticity there exists, in a small region of
parameter space, a closed curve acting as the attractor.


title:
Resistivity effects in surface superconductivity of thin films in strong
  magnetic fields

abstract:
  Phase slips creation in the thin film in perpendicular magnetic filed with
edge superconductivity is studied. These centers are due to thermal activation
of the order parameter below superconducting temperature transition leading to
the suppression of the superconductivity. The corresponding resistance is
calculated. The Alsamazov- Larkin correction to the conductivity above the
critical magnetic field destroying the surface superconductivity is studied.
Such structures could be applied as a new system for the study of the phase
slip phenomenon in one- dimensional superconducting wires.


title: Precision spectroscopy with two correlated atoms

abstract:
  We discuss techniques that allow for long coherence times in laser
spectroscopy experiments with two trapped ions. We show that for this purpose
not only entangled ions prepared in decoherence-free subspaces can be used but
also a pair of ions that are not entangled but subject to the same kind of
phase noise. We apply this technique to a measurement of the electric
quadrupole moment of the 3d D5/2 state of 40Ca+ and to a measurement of the
linewidth of an ultrastable laser exciting a pair of 40Ca+ ions.


title:
Simulations of the Poynting--Robertson Cosmic Battery in Resistive
  Accretion Disks

abstract:
  We describe the results of numerical "2.5--dimensional" MHD simulations of an
initially unmagnetized disk model orbiting a central point--mass and responding
to the continual generation of poloidal magnetic field due to a secular source
that emulates the Poynting--Robertson (PR) drag on electrons in the vicinity of
a luminous stellar or compact accreting object. The fluid in the disk and in
the surrounding hotter atmosphere has finite electrical conductivity and allows
for the magnetic field to diffuse freely out of the areas where it is
generated, while at the same time, the differential rotation of the disk twists
the poloidal field and quickly induces a substantial toroidal--field component.
The secular PR term has dual purpose in these simulations as the source of the
magnetic field and the trigger of a magnetorotational instability (MRI) in the
disk. The MRI is especially mild and does not destroy the disk because a small
amount of resistivity dampens the instability efficiently. In simulations with
moderate resistivities (diffusion timescales up to $\sim$16 local dynamical
times) and after $\sim$100 orbits, the MRI has managed to transfer outward
substantial amounts of angular momentum and the inner edge of the disk, along
with azimuthal magnetic flux, has flowed toward the central point--mass where a
new, magnetized, nuclear disk has formed. The toroidal field in this nuclear
disk is amplified by differential rotation and it cannot be contained; when it
approaches equipartition, it unwinds vertically and produces episodic jet--like
outflows. The poloidal field in the inner region cannot diffuse back out if the
characteristic diffusion time is of the order of or larger than the dynamical
time; it continues to grow linearly in time undisturbed and without saturation,
as the outer sections of many poloidal loops are being drawn radially outward.


title: A tutorial on conformal prediction

abstract:
  Conformal prediction uses past experience to determine precise levels of
confidence in new predictions. Given an error probability $\epsilon$, together
with a method that makes a prediction $\hat{y}$ of a label $y$, it produces a
set of labels, typically containing $\hat{y}$, that also contains $y$ with
probability $1-\epsilon$. Conformal prediction can be applied to any method for
producing $\hat{y}$: a nearest-neighbor method, a support-vector machine, ridge
regression, etc.
  Conformal prediction is designed for an on-line setting in which labels are
predicted successively, each one being revealed before the next is predicted.
The most novel and valuable feature of conformal prediction is that if the
successive examples are sampled independently from the same distribution, then
the successive predictions will be right $1-\epsilon$ of the time, even though
they are based on an accumulating dataset rather than on independent datasets.
  In addition to the model under which successive examples are sampled
independently, other on-line compression models can also use conformal
prediction. The widely used Gaussian linear model is one of these.
  This tutorial presents a self-contained account of the theory of conformal
prediction and works through several numerical examples. A more comprehensive
treatment of the topic is provided in "Algorithmic Learning in a Random World",
by Vladimir Vovk, Alex Gammerman, and Glenn Shafer (Springer, 2005).


title:
Exponentially Expanding Radiation Dominated and Dust Dominated Universes
  in Brans-Dicke Theory

abstract:
  The Brans-Dicke Theory of Gravity is one of the most promising alternatives
to the Einstein's Theory of General Relativity. We have examined an action term
with wrong signs for both the kinetic and mass terms for the scalar field and
have found solutions for both the scale factor of the universe and the
Brans-Dicke scalar field which vary exponentially in time.


title:
Equilibrium nano-shape changes induced by epitaxial stress (generalised
  Wulf-Kaishew theorem)

abstract:
  A generalised Wulf-Kaishew theorem is given describing the equilibrium shape
(ES) of an isolated 3D crystal A deposited coherently onto a lattice mismatched
planar substrate. For this purpose a free polyhedral crystal is formed then
homogeneously strained to be accommodated onto the lattice mismatched
substrate. During its elastic inhomogeneous relaxation the epitaxial contact
remains coherent so that the 3D crystal drags the atoms of the contact area and
produces a strain field in the substrate. The ES of the deposit is obtained by
minimising at constant volume the total energy (bulk and surface energies)
taking into account the bulk elastic relaxation. Our main results are: (1)
Epitaxial strain acts against wetting (adhesion) so that globally it leads to a
thickening of the ES. (2) Owing to strain the ES changes with size. More
precisely the various facets extension changes, some facets decreasing, some
others increasing. (3) Each dislocation entrance, necessary for relaxing
plastically too large crystals abruptly modifies the ES and thus the different
facets extension in a jerky way. (4) In all cases the usual self-similarity
with size is lost when misfit is considered. We illustrate these points in case
of box shaped and truncated pyramidal crystals. Some experimental evidences are
discussed.


title: Spinar Paradigm and Gamma Ray Bursts Central Engine

abstract:
  A spinar is a quasi-equilibrium collapsing object whose equilibrium is
maintained by the balance of centrifugal and gravitational forces and whose
evolution is determined by its magnetic field. The spinar quasi equilibrium
model recently discussed as the course for extralong X-ray plateu in GRB
(Lipunov & Gorbovskoy, 2007). We propose a simple non stationary
three-parameter collapse model with the determining role of rotation and
magnetic field in this paper. The input parameters of the theory are the mass,
angular momentum, and magnetic field of the collapsar. The model includes
approximate description of the following effects: centrifugal force,
relativistic effects of the Kerr metrics, pressure of nuclear matter,
dissipation of angular momentum due to magnetic field, decrease of the dipole
magnetic moment due to compression and general-relativity effects (the black
hole has no hare), neutrino cooling, time dilatation, and gravitational
redshift. The model describes the temporal behavior of the central engine and
demonstrates the qualitative variety of the types of such behavior in nature.
We apply our approach to explain the observed features of gamma-ray bursts of
all types. In particular, the model allows the phenomena of precursors, x-ray
and optical bursts, and the appearance of a plateau on time scales of several
thousand seconds to be unified.


title:
Hankel determinant and orthogonal polynomials for the Gaussian weight
  with a jump

abstract:
  We obtain asymptotics in n for the n-dimensional Hankel determinant whose
symbol is the Gaussian multiplied by a step-like function. We use
Riemann-Hilbert analysis of the related system of orthogonal polynomials to
obtain our results.


title: Crossing the Wall: Branes vs. Bundles

abstract:
  We test a recently proposed wall-crossing formula for the change of the
Hilbert space of BPS states in d=4,N=2 theories. We study decays of D4D2D0
systems into pairs of D4D2D0 systems and we show how the wall-crossing formula
reproduces results of Goettsche and Yoshioka on wall-crossing behavior of the
moduli of slope-stable holomorphic bundles over holomorphic surfaces. Our
comparison shows very clearly that the moduli space of the D4D2D0 system on a
rigid surface in a Calabi-Yau is not the same as the moduli space of torsion
free sheaves, even when worldhseet instantons are neglected. Moreover, we argue
that the physical formula should make some new mathematical predictions for a
future theory of the moduli of stable objects in the derived category.


title: Phase resolved spectroscopy of the Vela pulsar with XMM-Newton

abstract:
  The ~10^4 y old Vela Pulsar represents the bridge between the young Crab-like
and the middle-aged rotation powered pulsars. Its multiwavelength behaviour is
due to the superposition of different spectral components. We take advantage of
the unprecedented harvest of photons collected by XMM-Newton to assess the Vela
Pulsar spectral shape and to study the pulsar spectrum as a function of its
rotational phase. As for the middle-aged pulsars Geminga, PSR B0656+14 and PSR
B1055-52 (the "Three Musketeers"), the phase-integrated spectrum of Vela is
well described by a three-component model, consisting of two blackbodies
(T_bb1=(1.06+/-0.03)x10^6 K, R_bb1=5.1+/-0.3 km, T_bb2=(2.16+/-0.06)x10^6 K,
R_bb2=0.73+/-0.08 km) plus a power-law (gamma=2.2+/-0.3). The relative
contributions of the three components are seen to vary as a function of the
pulsar rotational phase. The two blackbodies have a shallow 7-9% modulation.
The cooler blackbody, possibly related to the bulk of the neutron star surface,
has a complex modulation, with two peaks per period, separated by ~0.35 in
phase, the radio pulse occurring exactly in between. The hotter blackbody,
possibly originating from a hot polar region, has a nearly sinusoidal
modulation, with a single, broad maximum aligned with the second peak of the
cooler blackbody, trailing the radio pulse by ~0.15 in phase. The non thermal
component, magnetospheric in origin, is present only during 20% of the pulsar
phase and appears to be opposite to the radio pulse. XMM-Newton phase-resolved
spectroscopy unveils the link between the thermally emitting surface of the
neutron star and its charge-filled magnetosphere, probing emission geometry as
a function of the pulsar rotation. This is a fundamental piece of information
for future 3-dimensional modeling of the pulsar magnetosphere.


title:
Genetic Transferability of Anomalous Irradiation Alterations of
  Antibiotic Activity

abstract:
  It previously has been discovered that visible light irradiation of
crystalline substrates can lead to enhancement of subsequent enzymatic reaction
rates as sharply peaked oscillatory functions of irradiation time. The
particular activating irradiation times can vary with source of a given enzyme
and thus, presumably, its molecular structure. The experiments reported here
demonstrate that the potential for this anomalous enzyme reaction rate
enhancement can be transferred from one bacterial species to another coincident
with transfer of the genetic determinant for the relevant enzyme. In
particular, the effect of crystal-irradiated chloramphenicol on growth of
bacterial strains in which a transferable R-factor DNA plasmid coding for
chloramphenicol resistance was or was not present (S. panama R+, E. coli R+,
and E. coli R-) was determined. Chloramphenicol samples irradiated 10, 35 and
60 sec produced increased growth rates (diminished inhibition) for the
resistant S. panama and E. coli strains, while having no such effect on growth
rate of the sensitive E. coli strain. Consistent with past findings,
chloramphenicol samples irradiated 5, 30 and 55 sec produced decreased growth
rates (increased inhibition) for all three strains.


title: Super Heavy Dark Matter and UHECR Anisotropy at Low Energy

abstract:
  Super Heavy quasi-stable particles are naturally produced in the early
universe and could represent a substantial fraction of the Dark Matter: the
so-called Super Heavy Dark Matter (SHDM). The decay of SHDM represents also a
possible source of Ultra High Energy Cosmic Rays (UHECR), with a reliably
calculated spectrum of the particles produced in the decay $(\propto
E^{-1.9})$. The SHDM model for the production of UHECR can explain
quantitatively only the excess of UHE events observed by AGASA. In the case of
an observed spectrum not showing the AGASA excess the SHDM model can provide
only a {\it subdominant} contribution to the UHECR flux. We discuss here the
basic features of SHDM for the production of a {\it subdominant} UHECR flux, we
refer our study to the possible signatures of the model at the Auger
observatory discussing in particular the expected chemical composition and
anisotropy.


title:
An HI study of three long-tailed irregular galaxies in the cluster
  Abell1367

abstract:
  We present the results on the distribution and kinematics of H$\sc{i}$ gas
with higher sensitivity and in one case of higher spectral resolution as well
than reported earlier, of three irregular galaxies CGCG 097073, 097079 and
097087 (UGC 06697) in the cluster Abell 1367. These galaxies are known to
exhibit long (50$-$75 kpc) tails of radio continuum and optical emission lines
(H$\alpha$) pointing away from the cluster centre and arcs of starformation on
the opposite sides of the tails. These features as well as the H{\sc i}
properties, with two of the galaxies (CGCG 097073 and 097079) exhibiting
sharper gradients in H{\sc i} intensity on the side of the tails, are
consistent with the H{\sc i} gas being affected by the ram pressure of the
intracluster medium. However the H{\sc i} emission in all the three galaxies
extends to much smaller distances than the radio-continuum and H$\alpha$ tails,
and are possibly still bound to the parent galaxies. Approximately 20$-$30 per
cent of the H{\sc i} mass is seen to accumulate on the downstream side due to
the effects of ram pressure.


title:
Overspinning a nearly extreme charged black hole via a quantum tunneling
  process

abstract:
  We examine a nearly extreme macroscopic Reissner-Nordstrom black hole in the
context of semi-classical gravity. The absorption rate associated with the
quantum tunneling process of scalar particles whereby this black hole can
acquire enough angular momentum to violate the weak cosmic censorship
conjecture is shown to be nonzero.


title: Scattering of twist fields from D-branes and orientifolds

abstract:
  We compute the two-point function for Z_N orbifold twist fields on the disk
and RP2. We apply this to a computation of the O(g_s) correction to the Kahler
potential for (the symmetric combination of) blow-up modes in type I string
theory on T^6/Z_3. This is related by supersymmetry to the one-loop field
dependent correction to the Fayet-Iliopoulos D-term for the anomalous U(1)
factor. We find this correction to be non-vanishing away from the orbifold
point.


title: Vortex generation in protoplanetary disks with an embedded giant planet

abstract:
  Vortices in protoplanetary disks can capture solid particles and form
planetary cores within shorter timescales than those involved in the standard
core-accretion model. We investigate vortex generation in thin unmagnetized
protoplanetary disks with an embedded giant planet with planet to star mass
ratio $10^{-4}$ and $10^{-3}$. Two-dimensional hydrodynamical simulations of a
protoplanetary disk with a planet are performed using two different numerical
methods. The results of the non-linear simulations are compared with a
time-resolved modal analysis of the azimuthally averaged surface density
profiles using linear perturbation theory. Finite-difference methods
implemented in polar coordinates generate vortices moving along the gap created
by Neptune-mass to Jupiter-mass planets. The modal analysis shows that unstable
modes are generated with growth rate of order $0.3 \Omega_K$ for azimuthal
numbers m=4,5,6, where $\Omega_K$ is the local Keplerian frequency.
Shock-capturing Cartesian-grid codes do not generate very much vorticity around
a giant planet in a standard protoplanetary disk. Modal calculations confirm
that the obtained radial profiles of density are less susceptible to the growth
of linear modes on timescales of several hundreds of orbital periods.
Navier-Stokes viscosity of the order $\nu=10^{-5}$ (in units of $a^2 \Omega_p$)
is found to have a stabilizing effect and prevents the formation of vortices.
This result holds at high resolution runs and using different types of boundary
conditions. Giant protoplanets of Neptune-mass to Jupiter-mass can excite the
Rossby wave instability and generate vortices in thin disks. The presence of
vortices in protoplanetary disks has implications for planet formation, orbital
migration, and angular momentum transport in disks.


title:
Volume Weighted Measures of Eternal Inflation in the Bousso-Polchinski
  Landscape

abstract:
  We consider the cosmological dynamics associated with volume weighted
measures of eternal inflation, in the Bousso-Polchinski model of the string
theory landscape. We find that this measure predicts that observers are most
likely to find themselves in low energy vacua with one flux considerably larger
than the rest. Furthermore, it allows for a satisfactory anthropic explanation
of the cosmological constant problem by producing a smooth, and approximately
constant, distribution of potentially observable values of Lambda. The low
energy vacua selected by this measure are often short lived. If we require
anthropically acceptable vacua to have a minimum life-time of 10 billion years,
then for reasonable parameters a typical observer should expect their vacuum to
have a life-time of approximately 12 billion years. This prediction is model
dependent, but may point toward a solution to the coincidence problem of
cosmology.


title:
Source Matching in the SDSS and RASS: Which Galaxies are Really X-ray
  Sources?

abstract:
  The current view of galaxy formation holds that all massive galaxies harbor a
massive black hole at their center, but that these black holes are not always
in an actively accreting phase. X-ray emission is often used to identify
accreting sources, but for galaxies that are not harboring quasars
(low-luminosity active galaxies), the X-ray flux may be weak, or obscured by
dust. To aid in the understanding of weakly accreting black holes in the local
universe, a large sample of galaxies with X-ray detections is needed. We
cross-match the ROSAT All Sky Survey (RASS) with galaxies from the Sloan
Digital Sky Survey Data Release 4 (SDSS DR4) to create such a sample. Because
of the high SDSS source density and large RASS positional errors, the
cross-matched catalog is highly contaminated by random associations. We
investigate the overlap of these surveys and provide a statistical test of the
validity of RASS-SDSS galaxy cross-matches. SDSS quasars provide a test of our
cross-match validation scheme, as they have a very high fraction of true RASS
matches. We find that the number of true matches between the SDSS main galaxy
sample and the RASS is highly dependent on the optical spectral classification
of the galaxy; essentially no star-forming galaxies are detected, while more
than 0.6% of narrow-line Seyferts are detected in the RASS. Also, galaxies with
ambiguous optical classification have a surprisingly high RASS detection
fraction. This allows us to further constrain the SEDs of low-luminosity active
galaxies. Our technique is quite general, and can be applied to any
cross-matching between surveys with well-understood positional errors.


title: Detecting Axion-Like Particles With Gamma Ray Telescopes

abstract:
  We propose that axion-like particles (ALPs) with a two-photon vertex,
consistent with all astrophysical and laboratory bounds, may lead to a
detectable signature in the spectra of high-energy gamma ray sources. This
occurs as a result of gamma rays being converted into ALPs in the magnetic
fields of efficient astrophysical accelerators according to the "Hillas
criterion", such as jets of active galactic nuclei or hot spots of radio
galaxies. The discovery of such an effect is possible by GLAST in the 1-100 GeV
range and by ground based gamma ray telescopes in the TeV range.


title: Optimal purifications and fidelity for displaced thermal states

abstract:
  We evaluate the Uhlmann fidelity between two one-mode displaced thermal
states as the maximal probability transition between appropriate purifications
of the given states. The optimal purifications defining the fidelity are proved
to be two-mode displaced Gaussian states.


title:
Exact Solutions of the Isothermal Lane--Emden Equation with Rotation and
  Implications for the Formation of Planets and Satellites

abstract:
  We have derived exact solutions of the isothermal Lane--Emden equation with
and without rotation in a cylindrical geometry. The corresponding hydrostatic
equilibria are most relevant to the dynamics of the protosolar nebula before
and during the stages of planet and satellite formation. The nonrotating
solution for the mass density is analytic, nonsingular, monotonically
decreasing with radius, and it satisfies easily the usual physical boundary
conditions at the center. When differential rotation is added to the
Lane--Emden equation, an entire class of exact solutions for the mass density
appears. We have determined all of these solutions analytically as well. Within
this class, solutions that are power laws or combinations of power laws are not
capable of satisfying the associated boundary--value problem, but they are
nonetheless of profound importance because they constitute "baselines" to which
the actual solutions approach when the central boundary conditions are imposed.
Numerical integrations that enforce such physical boundary conditions show that
the actual radial equilibrium density profiles emerge from the center close to
the nonrotating solution, but once they cross below the corresponding
baselines, they cease to be monotonic. The actual solutions are forced to
oscillate permanently about the baseline solutions without ever settling onto
them because the central boundary conditions strictly prohibit such settling,
even in the asymptotic regime of large radii. Based on our results, we expect
that quasistatically--evolving protoplanetary disks should develop oscillatory
density profiles in their midplanes during their isothermal phase. The peaks in
these profiles correspond to local potential minima and their locations are
ideal sites for the formation of protoplanets ...


title:
A Spectroscopic Study of Mass Outflows in the Interacting Binary RY
  Scuti

abstract:
  The massive interacting binary RY Scuti is an important representative of an
active mass-transferring system that is changing before our eyes and which may
be an example of the formation of a Wolf-Rayet star through tidal stripping.
Utilizing new and previously published spectra, we present examples of how a
number of illustrative absorption and emission features vary during the binary
orbit. We identify spectral features associated with each component, calculate
a new, double-lined spectroscopic binary orbit, and find masses of 7.1 +/- 1.2
M_sun for the bright supergiant and 30.0 +/- 2.1 M_sun for the hidden massive
companion. Through tomographic reconstruction of the component spectra from the
composite spectra, we confirm the O9.7 Ibpe spectral class of the bright
supergiant and discover a B0.5 I spectrum associated with the hidden massive
companion; however, we suggest that the latter is actually the spectrum of the
photosphere of the accretion torus immediately surrounding the massive
companion. We describe the complex nature of the mass loss flows from the
system in the context of recent hydrodynamical models for beta Lyr, leading us
to conclude RY Scuti has matter leaving the system in two ways: 1) a bipolar
outflow from winds generated by the hidden massive companion, and 2) mass from
the bright O9.7 Ibpe supergiant flowing from the region near the L2 point to
fill out a large, dense circumbinary disk. This circumbinary disk (radius ~ 1
AU) may feed the surrounding double-toroidal nebula (radius ~ 2000 AU).


title:
Mirror symmetry and T-duality in the complement of an anticanonical
  divisor

abstract:
  We study the geometry of complexified moduli spaces of special Lagrangian
submanifolds in the complement of an anticanonical divisor in a compact Kahler
manifold. In particular, we explore the connections between T-duality and
mirror symmetry in concrete examples, and show how quantum corrections arise in
this context.


title: The chiral condensate in a constant electromagnetic field

abstract:
  We study the shift of the chiral condensate in a constant electromagnetic
field in the context of chiral perturbation theory. Using the Schwinger
proper-time formalism, we derive a one-loop expression correct to all orders in
$m_{\pi}^2 / eH$. Our result correctly reproduces a previously derived
``low-energy theorem'' for $m_\pi = 0$. We show that it is essential to include
corrections due to non-vanishing $m_\pi$ in order for a low energy theorem to
have any approximate regime of validity in the physical universe. We generalize
these results to systems containing electric fields, and discuss the regime of
validity for the results. In particular, we discuss the circumstances in which
the method formally breaks down due to pair creation in an electric field.


title: GRB060218 and GRBs associated with Supernovae Ib/c

abstract:
  We plan to fit the complete gamma- and X-ray light curves of the long
duration GRB060218, including the prompt emission, in order to clarify the
nature of the progenitors and the astrophysical scenario of the class of GRBs
associated to SNe Ib/c. The initial total energy of the electron-positron
plasma E_{e^\pm}^{tot}=2.32\times 10^{50} erg has a particularly low value
similarly to the other GRBs associated with SNe. For the first time we observe
a baryon loading B=10^{-2} which coincides with the upper limit for the
dynamical stability of the fireshell. The effective CircumBurst Medium (CBM)
density shows a radial dependence n_{cbm} \propto r^{-\alpha} with
1.0<\alpha<1.7 and monotonically decreases from 1 to 10^{-6} particles/cm^3.
Such a behavior is interpreted as due to a fragmentation in the fireshell.
Analogies with the fragmented density and filling factor characterizing Novae
are outlined. The fit presented is particularly significant in view of the
complete data set available for GRB060218 and of the fact that it fulfills the
Amati relation. We fit GRB060218, usually considered as an X-Ray Flash (XRF),
as a "canonical GRB" within our theoretical model. The smallest possible black
hole, formed by the gravitational collapse of a neutron star in a binary
system, is consistent with the especially low energetics of the class of GRBs
associated with SNe Ib/c. We give the first evidence for a fragmentation in the
fireshell. Such a fragmentation is crucial in explaining both the unusually
large T_{90} and the consequently inferred abnormal low value of the CBM
effective density.


title: Self-interaction correction with Wannier functions

abstract:
  We describe the behavior of the Perdew-Zunger self-interaction-corrected
local density approximation (SIC-LDA) functional when implemented in a
plane-wave pseudopotential formalism with Wannier functions. Prototypical
semiconductors and wide-bandgap oxides show a large overcorrection of the LDA
bandgap. Application to transition-metal oxides and elements with d electrons
is hindered by a serious breaking of the spherical symmetry, which appears even
in a closed shell free atom. Our results indicate that, when all spherical
approximations are lifted, the general applicability of orbital-dependent
potentials is very limited and should be reconsidered in favor of rotationally
invariant functionals.


title: Path probability density functions for semi-Markovian random walks

abstract:
  In random walks, the path representation of the Green's function is an
infinite sum over the length of path probability density functions (PDFs). Here
we derive and solve, in Laplace space, the recursion relation for the n order
path PDF for any arbitrarily inhomogeneous semi-Markovian random walk in a
one-dimensional (1D) chain of L states. The recursion relation relates the n
order path PDF to L/2 (round towards zero for an odd L) shorter path PDFs, and
has n independent coefficients that obey a universal formula. The z transform
of the recursion relation straightforwardly gives the generating function for
path PDFs, from which we obtain the Green's function of the random walk, and
derive an explicit expression for any path PDF of the random walk. These
expressions give the most detailed description of arbitrarily inhomogeneous
semi-Markovian random walks in 1D.


title: Linear Stability of Closed Timelike Geodesics

abstract:
  The linear stability of closed timelike geodesics (CTGs) is analyzed in two
spacetimes with cylindrical sources, an infinite rotating dust cylinder, and a
cylindrical cloud of static cosmic strings with a central spinning string. We
also study the existence and linear stability of closed timelike curves in
spacetimes that share some common features with the G\"odel universe
(G\"odel-type spacetimes). In this case the existence of CTGs depends on the
`background' metric. The CTGs in a subclass of inhomogeneous stationary
cosmological solutions of the Einstein-Maxwell equations with topology $
S^3\times \mathbb R$ are also examined.


title:
A Spitzer IRAC Census of the Asymptotic Giant Branch Populations in
  Local Group Dwarfs. II. IC 1613

abstract:
  We present Spitzer Space Telescope IRAC photometry of the Local Group dwarf
irregular galaxy IC 1613. We compare our 3.6, 4.5, 5.8, and 8.0 micron
photometry with broadband optical photometry and find that the optical data do
not detect 43% and misidentify an additional 11% of the total AGB population,
likely because of extinction caused by circumstellar material. Further, we find
that a narrowband optical carbon star study of IC 1613 detects 50% of the total
AGB population and only considers 18% of this population in calculating the
carbon to M-type AGB ratio. We derive an integrated mass-loss rate from the AGB
stars of 0.2-1.0 x 10^(-3) solar masses per year and find that the distribution
of bolometric luminosities and mass-loss rates are consistent with those for
other nearby metal-poor galaxies. Both the optical completeness fractions and
mass-loss rates in IC 1613 are very similar to those in the Local Group dwarf
irregular, WLM, which is expected given their similar characteristics and
evolutionary histories.


title: Reheating a multi-throat universe by brane motion

abstract:
  We propose a mechanism of reheating after inflation in multi-throat scenarios
of warped extra dimensions. Validity of an effective field theory on the
standard model (SM) brane requires that the position of the SM brane during
inflation be different from the position after inflation. The latter is
supposed to be near the tip of the SM throat but the former is not. After
inflation, when the Hubble expansion rate becomes sufficiently low, the SM
brane starts moving towards the tip and eventually oscillates. The SM fields
are excited by the brane motion and the universe is reheated. Since interaction
between the brane position modulus and the SM fields is suppressed only by the
local string scale, the modulus effectively decays into the SM fields.


title:
Theory of the Nernst effect near quantum phase transitions in condensed
  matter, and in dyonic black holes

abstract:
  We present a general hydrodynamic theory of transport in the vicinity of
superfluid-insulator transitions in two spatial dimensions described by
"Lorentz"-invariant quantum critical points. We allow for a weak impurity
scattering rate, a magnetic field B, and a deviation in the density, \rho, from
that of the insulator. We show that the frequency-dependent thermal and
electric linear response functions, including the Nernst coefficient, are fully
determined by a single transport coefficient (a universal electrical
conductivity), the impurity scattering rate, and a few thermodynamic state
variables. With reasonable estimates for the parameters, our results predict a
magnetic field and temperature dependence of the Nernst signal which resembles
measurements in the cuprates, including the overall magnitude. Our theory
predicts a "hydrodynamic cyclotron mode" which could be observable in ultrapure
samples. We also present exact results for the zero frequency transport
co-efficients of a supersymmetric conformal field theory (CFT), which is
solvable by the AdS/CFT correspondence. This correspondence maps the \rho and B
perturbations of the 2+1 dimensional CFT to electric and magnetic charges of a
black hole in the 3+1 dimensional anti-de Sitter space. These exact results are
found to be in full agreement with the general predictions of our hydrodynamic
analysis in the appropriate limiting regime. The mapping of the hydrodynamic
and AdS/CFT results under particle-vortex duality is also described.


title: Bubble-Wrap for Bullets: The Stability Imparted By A Thin Magnetic Layer

abstract:
  There has been significant recent work which examines a situation where a
thin magnetic layer is `draped' over a core merging into a larger cluster; the
same process also appears to be at work at a bubble rising from the cluster
centre. Such a thin magnetic layer could thermally isolate the core from the
cluster medium, but only if the same shear process which generates the layer
does not later disrupt it. On the other hand, if the magnetized layer can
stabilize against the shear instabilities, then the magnetic layer can have the
additional dynamical effect of reducing the shear-driven mixing of the core's
material during the merger process. These arguments could equally well to
underdense cluster bubbles, which would be even more prone to disruption. While
it is well known that magnetic fields can suppress instabilities, it is less
clear that a thin layer can suppress instabilities on scales significantly
larger than its thickness. Here we consider the stability imparted by a thin
magnetized layer. Such a layer can have a significant stabilizing effect even
on modes with wavelengths much larger than the thickness of the layer l; to
stabilize modes ten times larger requires only that the Alfv\'en speed in the
magnetized layer is comparable to the relevant destabilizing velocity -- the
shear velocity in the case of pure Kelvin-Helmholtz like instability, or a
typical buoyancy velocity in the case of pure Rayleigh-Taylor. We confirm our
calculations with two-dimensional numerical experiments using the Athena code.


title: Convolution estimates and model surfaces of low codimension

abstract:
  We give examples of measures on certain k-surfaces in R^d. These measures
satisfy convolution estimates which are nearly optimal.


title: Computing word length in alternate presentations of Thompson's group F

abstract:
  We introduce a new method for computing the word length of an element of
Thompson's group F with respect to a "consecutive" generating set of the form
X_n={x_0,x_1,...,x_n}, which is a subset of the standard infinite generating
set for F. We use this method to show that (F,X_n) is not almost convex, and
has pockets of increasing, though bounded, depth dependent on n.


title:
Universal Science of Complexity: Consistent Understanding of Ecological,
  Living and Intelligent System Dynamics

abstract:
  A major challenge of interdisciplinary description of complex system
behaviour is whether real systems of higher complexity levels can be understood
with at least the same degree of objective, "scientific" rigour and
universality as "simple" systems of classical, Newtonian science paradigm. The
problem is reduced to that of arbitrary, many-body interaction (unsolved in
standard theory). Here we review its causally complete solution, the ensuing
concept of complexity and applications. The discovered key properties of
dynamic multivaluedness and entanglement give rise to a qualitatively new kind
of mathematical structure providing the exact version of real system behaviour.
The extended mathematics of complexity contains the truly universal definition
of dynamic complexity, randomness (chaoticity), classification of all possible
dynamic regimes, and the unifying principle of any system dynamics and
evolution, the universal symmetry of complexity. Every real system has a
non-zero (and actually high) value of unreduced dynamic complexity determining,
in particular, "mysterious" behaviour of quantum systems and relativistic
effects causally explained now as unified manifestations of complex interaction
dynamics. The observed differences between various systems are due to different
regimes and levels of their unreduced dynamic complexity. We outline
applications of universal concept of dynamic complexity emphasising cases of
"truly complex" systems from higher complexity levels (ecological and living
systems, brain operation, intelligence and consciousness, autonomic information
and communication systems) and show that the urgently needed progress in social
and intellectual structure of civilisation inevitably involves qualitative
transition to unreduced complexity understanding (we call it "revolution of
complexity").


title:
Reionization and the large-scale 21 cm-cosmic microwave background cross
  correlation

abstract:
  Of the many probes of reionization, the 21 cm line and the cosmic microwave
background (CMB) are among the most effective. We examine how the
cross-correlation of the 21 cm brightness and the CMB Doppler fluctuations on
large angular scales can be used to study this epoch. We employ a new model of
the growth of large scale fluctuations of the ionized fraction as reionization
proceeds. We take into account the peculiar velocity field of baryons and show
that its effect on the cross correlation can be interpreted as a mixing of
Fourier modes. We find that the cross-correlation signal is strongly peaked
toward the end of reionization and that the sign of the correlation should be
positive because of the inhomogeneity inherent to reionization. The signal
peaks at degree scales (l~100) and comes almost entirely from large physical
scales (k~0.01 Mpc). Since many of the foregrounds and noise that plague low
frequency radio observations will not correlate with CMB measurements, the
cross correlation might appear to provide a robust diagnostic of the
cosmological origin of the 21 cm radiation around the epoch of reionization.
Unfortunately, we show that these signals are actually only weakly correlated
and that cosmic variance dominates the error budget of any attempted detection.
We conclude that the detection of a cross-correlation peak at degree-size
angular scales is unlikely even with ideal experiments.


title: Curvature line parametrization from circle patterns

abstract:
  We study local and global approximations of smooth nets of curvature lines
and smooth conjugate nets by respective discrete nets (circular nets and planar
quadrilateral nets) with infinitesimal quads. It is shown that choosing the
points of discrete nets on the smooth surface one can obtain second-order
approximation globally. Also a simple geometric construction for approximate
determination of principal directions of smooth surfaces is given.


title: The FIRST-2MASS Red Quasar Survey

abstract:
  Combining radio observations with optical and infrared color selection --
demonstrated in our pilot study to be an efficient selection algorithm for
finding red quasars -- we have obtained optical and infrared spectroscopy for
120 objects in a complete sample of 156 candidates from a sky area of 2716
square degrees. Consistent with our initial results, we find our selection
criteria -- J-K>1.7, R-K>4.0 -- yield a ~50% success rate for discovering
quasars substantially redder than those found in optical surveys. Comparison
with UVX- and optical color-selected samples shows that >~ 10% of the quasars
are missed in a magnitude-limited survey. Simultaneous two-frequency radio
observations for part of the sample indicate that a synchrotron continuum
component is ruled out as a significant contributor to reddening the quasars'
spectra. We go on to estimate extinctions for our objects assuming their red
colors are caused by dust. Continuum fits and Balmer decrements suggest E(B-V)
values ranging from near zero to 2.5 magnitudes. Correcting the K-band
magnitudes for these extinctions, we find that for K <= 14.0, red quasars make
up between 25% and 60% of the underlying quasar population; owing to the
incompleteness of the 2MASS survey at fainter K-band magnitudes, we can only
set a lower limit to the radio-detected red quasar population of >20-30%.


title: Smooth maps of a foliated manifold in a symplectic manifold

abstract:
  The immersions of a smooth manifold $M$ in a symplectic manifold $(N,\sigma)$
inducing a given closed form $\omega$ on $M$ satisfy the $C^0$-dense
$h$-principle in the space of all continuous maps which pull back the deRham
cohomology class of $\sigma$ onto that of $\omega$. In this paper we prove a
foliated version of this result due to Gromov.


title: Fermi-Frenet coordinates for space-like curves

abstract:
  We generalize Fermi coordinates, which correspond to an adapted set of
coordinates describing the vicinity of an observer's worldline, to the
worldsheet of an arbitrary spatial curve in a static spacetime. The spatial
coordinate axes are fixed using a covariant Frenet triad so that the metric can
be expressed using the curvature and torsion of the spatial curve. As an
application of Fermi-Frenet coordinates, we show that they allow covariant
inertial forces to be expressed in a simple and physically intuitive way.


title: Seeking the best Internet Model

abstract:
  The models of the Internet reported in the literature are mainly aimed at
reproducing the scale-free structure, the high clustering coefficient and the
small world effects found in the real Internet, while other important
properties (e.g. related to centrality and hierarchical measurements) are not
considered. For a better characterization and modeling of such network, a
larger number of topological properties must be considered. In this work, we
present a sound multivariate statistical approach, including feature spaces and
multivariate statistical analysis (especially canonical projections), in order
to characterize several Internet models while considering a larger set of
relevant measurements. We apply such a methodology to determine, among nine
complex networks models, which are those most compatible with the real Internet
data (on the autonomous systems level) considering a set of 21 network
measurements. We conclude that none of the considered models can reproduce the
Internet topology with high accuracy.


title: Convex Hull Realizations of the Multiplihedra

abstract:
  We present a simple algorithm for determining the extremal points in
Euclidean space whose convex hull is the nth polytope in the sequence known as
the multiplihedra. This answers the open question of whether the multiplihedra
could be realized as convex polytopes. We use this realization to unite the
approach to A_n-maps of Iwase and Mimura to that of Boardman and Vogt. We
include a review of the appearance of the nth multiplihedron for various n in
the studies of higher homotopy commutativity, (weak) n-categories,
A_infinity-categories, deformation theory, and moduli spaces. We also include
suggestions for the use of our realizations in some of these areas as well as
in related studies, including enriched category theory and the graph
associahedra.


title: Final state interactions and hadron quenching in cold nuclear matter

abstract:
  I examine the role of final state interactions in cold nuclear matter in
modifying hadron production on nuclear targets with leptonic or hadronic beams.
I demonstrate the extent to which available experimental data in
electron-nucleus collisions can give direct information on final state effects
in hadron-nucleus and nucleus-nucleus collisions. For hadron-nucleus
collisions, a theoretical estimate based on a parton energy loss model tested
in lepton-nucleus collisions shows a large effect on mid-rapidity hadrons at
fixed target experiments. At RHIC energy, the effect is large for negative
rapidity hadrons, but mild at midrapidity. This final state cold hadron
quenching needs to be taken into account in jet tomographic analysis of the
medium created in nucleus-nucleus collisions.


title: Ohm's Law at strong coupling: S duality and the cyclotron resonance

abstract:
  We calculate the electrical and thermal conductivities and the thermoelectric
coefficient of a class of strongly interacting 2+1 dimensional conformal field
theories with anti-de Sitter space duals. We obtain these transport
coefficients as a function of charge density, background magnetic field,
temperature and frequency. We show that the thermal conductivity and
thermoelectric coefficient are determined by the electrical conductivity alone.
At small frequency, in the hydrodynamic limit, we are able to provide a number
of analytic formulae for the electrical conductivity. A dominant feature of the
conductivity is the presence of a cyclotron pole. We show how bulk
electromagnetic duality acts on the transport coefficients.


title: Stringy product on twisted orbifold K-theory for abelian quotients

abstract:
  In this paper we present a model to calculate the stringy product on twisted
orbifold K-theory of Adem-Ruan-Zhang for abelian complex orbifolds.
  In the first part we consider the non-twisted case on an orbifold presented
as the quotient of a manifold acted by a compact abelian Lie group. We give an
explicit description of the obstruction bundle, we explain the relation with
the product defined by Jarvis-Kaufmann-Kimura and, via a Chern character map,
with the Chen-Ruan cohomology, and we explicitely calculate the stringy product
for a weighted projective orbifold.
  In the second part we consider orbifolds presented as the quotient of a
manifold acted by a finite abelian group and twistings coming from the group
cohomology. We show a decomposition formula for twisted orbifold K-theory that
is suited to calculate the stringy product and we use this formula to calculate
two examples when the group is $(\integer/2)^3$.


title:
Steady states and linear stability analysis of precipitation pattern
  formation at geothermal hot springs

abstract:
  A dynamical theory of geophysical precipitation pattern formation is
presented and applied to irreversible calcium carbonate (travertine)
deposition. Specific systems studied here are the terraces and domes observed
at geothermal hot springs, such as those at Yellowstone National Park, and
speleothems, particularly stalactites and stalagmites. The theory couples the
precipitation front dynamics with shallow water flow, including corrections for
turbulent drag and curvature effects. In the absence of capillarity and with a
laminar flow profile, the theory predicts a one-parameter family of steady
state solutions to the moving boundary problem describing the precipitation
front. These shapes match well the measured shapes near the vent at the top of
observed travertine domes. Closer to the base of the dome, the solutions
deviate from observations, and circular symmetry is broken by a fluting
pattern, which we show is associated with capillary forces causing thin film
break-up. We relate our model to that recently proposed for stalactite growth,
and calculate the linear stability spectrum of both travertine domes and
stalactites. Lastly, we apply the theory to the problem of precipitation
pattern formation arising from turbulent flow down an inclined plane, and
identify a linear instability that underlies scale-invariant travertine terrace
formation at geothermal hot springs.


title: World-sheet dynamics of ZZ branes

abstract:
  We show how non-compact space-time (ZZ branes) emerges as a limit of compact
space-time (FZZT branes) for specific ratios between the square of the boundary
cosmological constant and the bulk cosmological constant in the (2,2m-1)
minimal model coupled to two-dimensional quantum gravity.


title: Asymptotic probability density functions in turbulence

abstract:
  A formalism is presented to obtain closed evolution equations for asymptotic
probability distribution functions of turbulence magnitudes. The formalism is
derived for a generic evolution equation, so that the final result can be
easily applied to rather general problems. Although the approximation involved
cannot be ascertained a priori, we show that application of the formalism to
well known problems gives the correct results.


title:
Origin of the X-ray Quasi-Periodic Oscillations and Identification of a
  Transient Ultraluminous X-Ray Source in M82

abstract:
  The starburst galaxy M82 contains two ultraluminous X-ray sources (ULXs),
CXOM82 J095550.2+694047 (=X41.4+60) and CXOM82 J095551.1+694045 (=X42.3+59),
which are unresolved by XMM-Newton. We revisited the two XMM-Newton
observations of M82 and analyzed the surface brightness profiles using the
known Chandra source positions. We show that the quasi-periodic oscillations
(QPOs) detected with XMM-Newton originate from X41.4+60, the brightest X-ray
source in M82. Correcting for the contributions of the unresolved sources, the
QPO at a frequency of 55.8+/-1.3 mHz on 2001 May 06 had a fractional rms
amplitude of 32%, and the QPO at 112.9+/-1.3 mHz on 2004 April 21 had an
amplitude of 21%. The QPO frequency may possibly be correlated with the source
flux, similar to the type C QPOs in XTE 1550-564 and GRS 1915+105, but at
luminosities two orders of magnitude higher. X42.3+59, the second brightest
source in M82, displayed a strikingly high flux of 1.4E-11 ergs/cm^2/s in the
2-10 keV band on 2001 May 6. A seven-year light curve of X42.3+59 shows extreme
variability over a factor of 1000; the source is not detected in several
Chandra observations. This transient behavior suggests accretion from an
unstable disk. If the companion star is massive, as might be expected in the
young stellar environment, then the compact object would likely be an IMBH.


title:
Reverse engineering time discrete finite dynamical systems: A feasible
  undertaking?

abstract:
  With the advent of high-throughput profiling methods, interest in reverse
engineering the structure and dynamics of biochemical networks is high.
Recently an algorithm for reverse engineering of biochemical networks was
developed by Laubenbacher and Stigler. It is a top-down approach using time
discrete dynamical systems. One of its key steps includes the choice of a term
order. The aim of this paper is to identify minimal requirements on data sets
to be used with this algorithm and to characterize optimal data sets. We found
minimal requirements on a data set based on how many terms the functions to be
reverse engineered display. Furthermore, we identified optimal data sets, which
we characterized using a geometric property called "general position".
Moreover, we developed a constructive method to generate optimal data sets,
provided a codimensional condition is fulfilled. In addition, we present a
generalization of their algorithm that does not depend on the choice of a term
order. For this method we derived a formula for the probability of finding the
correct model, provided the data set used is optimal. We analyzed the
asymptotic behavior of the probability formula for a growing number of
variables n (i.e. interacting chemicals). Unfortunately, this formula converges
to zero as fast as r^(q^n), where q is a natural number and 0<r<1. Therefore,
even if an optimal data set is used and the restrictions in using term orders
are overcome, the reverse engineering problem remains unfeasible, unless
prodigious amounts of data are available. Such large data sets are
experimentally impossible to generate with today's technologies.


title:
Tau and muon pair production cross-sections in electron-positron
  annihilations at sqrt{s} = 10.58 GeV

abstract:
  The calculational precision of $\ee\to\tautau$ and $\ee\to\mumu$ production
cross-sections in electron-positron annihilations at \roots = 10.58 \gev are
studied for the \kk Monte Carlo simulation program. We determine
$\sigma(\ee\to\tautau) = (0.919 \pm 0.003) \nb$ and $\sigma(\ee\to\mumu) =
(1.147 \pm 0.005) \nb$, where the error represents the precision of the
calculation.


title: Measurement of Aerosols at the Pierre Auger Observatory

abstract:
  The air fluorescence detectors (FDs) of the Pierre Auger Observatory are
vital for the determination of the air shower energy scale. To compensate for
variations in atmospheric conditions that affect the energy measurement, the
Observatory operates an array of monitoring instruments to record hourly
atmospheric conditions across the detector site, an area exceeding 3,000 square
km. This paper presents results from four instruments used to characterize the
aerosol component of the atmosphere: the Central Laser Facility (CLF), which
provides the FDs with calibrated laser shots; the scanning backscatter lidars,
which operate at three FD sites; the Aerosol Phase Function monitors (APFs),
which measure the aerosol scattering cross section at two FD locations; and the
Horizontal Attenuation Monitor (HAM), which measures the wavelength dependence
of aerosol attenuation.


title:
Blow-up of Electric Fields between Closely Spaced Spherical Perfect
  Conductors

abstract:
  The electric field increases toward infinity in the narrow region between
closely adjacent perfect conductors as they approach each other. Much attention
has been devoted to the blow-up estimate, especially in two dimensions, for the
practical relevance to high stress concentration in fiber-reinforced elastic
composites. In this paper, we establish optimal estimates for the electric
field associated with the distance between two spherical conductors in
$n-${dimensional spaces for $n \geq 2$}. {The novelty of these estimates is
that they explicitly describe the dependency of the blow-up rate on the
geometric parameters: the radii of the conductors.}


title: Perturbation theory of spherically symmetric self-similar black holes

abstract:
  The theory of perturbations of spherically symmetric self-similar black holes
is presented, in the Newman-Penrose formalism. It is shown that the wave
equations for gravitational, electromagnetic, and scalar waves are separable,
though not decoupled. A generalization of the Teukolsky equation is given.
Monopole and dipole modes are treated. The Newman-Penrose wave equations
governing polar and axial spin-0 perturbations are explored.


title: Black hole entropy, curved space and monsters

abstract:
  We investigate the microscopic origin of black hole entropy, in particular
the gap between the maximum entropy of ordinary matter and that of black holes.
Using curved space, we construct configurations with entropy greater than their
area in Planck units. These configurations have pathological properties and we
refer to them as monsters. When monsters are excluded we recover the entropy
bound on ordinary matter $S < A^{3/4}$. This bound implies that essentially all
of the microstates of a semiclassical black hole are associated with the growth
of a slightly smaller black hole which absorbs some additional energy. Our
results suggest that the area entropy of black holes is the logarithm of the
number of distinct ways in which one can form the black hole from ordinary
matter and smaller black holes, but only after the exclusion of monster states.


title:
Spin current and electrical polarization in GaN double-barrier
  structures

abstract:
  Tunnel spin polarization in a piezoelectric AlGaN/GaN double barrier
structure is calculated. It is shown that the piezoelectric field and the
spontaneous electrical polarization increase an efficiency of the tunnel spin
injection. The relation between the electrical polarization and the spin
orientation allows engineering a zero magnetic field spin injection
manipulating the lattice-mismatch strain with an Al-content in the barriers.


title:
Phenomenological features in a model with non-universal gaugino CP
  phases

abstract:
  We study phenomenological features in an extended gauge mediation SUSY
breaking model which has non-universal gaugino masses and CP phases. We show
that large CP phases in soft SUSY breaking parameters can be consistent with
the constraints coming from the electric dipole moment (EDM) of an electron, a
neutron, and also a mercury atom. Masses of the superpartners are not
necessarily required to be larger than 1 TeV but allowed to be O(100) GeV. We
also investigate the mass spectrum of Higgs scalars and their couplings to
gauge bosons in that case. Compatibility of this model with the present
experimental data on the Higgs sector is discussed.


title: Quantum decay rates in chaotic scattering

abstract:
  In this article we prove that for a large class of operators, including
Schroedinger operators, with hyperbolic classical flows, the smallness of
dimension of the trapped set implies that there is a gap between the resonances
and the real axis. In other words, the quantum decay rate is bounded from below
if the classical repeller is sufficiently filamentary. The higher dimensional
statement is given in terms of the topological pressure. Under the same
assumptions we also prove a resolvent estimate with a logarithmic loss compared
to nontrapping estimates.


title:
Quark deconfinement in neutron star cores and the ground state of
  neutral matter

abstract:
  Whether or not deconfined quark phase exists in neutron star cores and
represents the ground state of neutral matter at moderate densities are open
questions. We use two realistic effective quark models, the three-flavor
Nambu-Jona-Lasinio model and the modified quark-meson coupling model, to
describe the neutron star matter. After constructing possible hybrid equations
of state (EOSes) with unpaired or color superconducting quark phase, we
systematically discuss the observational constraints of neutron stars on the
EOSes. It is found that the neutron star with pure quark matter core is
unstable and the hadronic phase with hyperons is denied, while hybrid EOSes
with two-flavor color superconducting phase or unpaired quark matter phase are
both allowed by the tight and most reliable constraints from two stars Ter 5 I
and EXO 0748-676. And the hybrid EOS with unpaired quark matter phase is
allowed even compared with the tightest constraint from the most massive pulsar
star PSR J0751+1807. Therefore, we conclude that the ground state of neutral
matter at moderate densities is in deconfined quark phase likely.


title: A non-perturbative study of non-commutative U(1) gauge theory

abstract:
  We study U(1) gauge theory on a 4d non-commutative torus, where two
directions are non-commutative. Monte Carlo simulations are performed after
mapping the regularized theory onto a U(N) lattice gauge theory in d=2. At
intermediate coupling strength, we find a phase in which open Wilson lines
acquire non-zero vacuum expectation values, which implies the spontaneous
breakdown of translational invariance. In this phase, various physical
quantities obey clear scaling behaviors in the continuum limit with a fixed
non-commutativity parameter theta, which provides evidence for a possible
continuum theory. In the weak coupling symmetric phase, the dispersion relation
involves a negative IR-singular term, which is responsible for the observed
phase transition.


title: The total energy-momentum of the universe in teleparallel gravity

abstract:
  We investigate the conservation law of energy-momentum in teleparallel
gravity by using general Noether theorem. The energy-momentum current has also
superpotential and is therefore identically conserved. The total
energy-momentum, which includes the contributions of both matter and
gravitational fields, is given by the integral of scalar densities over a
three-dimensional spacelike hypersurface. As an example, the universe in
teleparallel gravity is investigated. It is shown that the total
energy-momentum vanishes independently of both the curvature parameter and the
three dimensionless coupling constants of teleparallel gravity.


title: On finite groups whose derived subgroup has bounded rank

abstract:
  Let $G$ be a finite group with derived subgroup of rank $r$. We prove that
$\gzz\leq |G'|^{2r}$. Motivated by the results of I. M. Isaacs in \cite{isa} we
show that if $G$ is capable then $\gz\leq |G'|^{4r}$. This answers a question
of L. Pyber. We prove that if $G$ is a capable $p$-group then the rank of
$G/\mathbf{Z}(G)$ is bounded above in terms of the rank of $G'$.


title: Relativistic rapidity as change in musical pitch

abstract:
  Relativistic rapidity is usually presented as a computational device. As
Levy-Leblond has shown, it is also the velocity that would be imputed by an
ideal Newtonian inertial guidance system, taking c=1*neper=1. Here, we show
that it can also be interpreted as the change in musical pitch of radiation
fore and aft along the direction of motion.


title: Compensation of the Crossing Angle with Crab Cavities at KEKB

abstract:
  Crab cavities have been installed in the KEKB B--Factory rings to compensate
the crossing angle at the collision point and thus increase luminosity. The
beam operation with crab crossing has been done since February 2007. This is
the first experience with such cavities in colliders or storage rings. The crab
cavities have been working without serious issues. While higher specific
luminosity than the geometrical gain has been achieved, further study is
necessary and under way to reach the prediction of simulation.


title: Multiplicity free expansions of Schur $P$-functions

abstract:
  After deriving inequalities on coefficients arising in the expansion of a
Schur $P$-function in terms of Schur functions we give criteria for when such
expansions are multiplicity free. From here we study the multiplicity of an
irreducible spin character of the twisted symmetric group in the product of a
basic spin character with an irreducible character of the symmetric group, and
determine when it is multiplicity free.


title: Compact symmetric solutions to the postage stamp problem

abstract:
  We derive lower and upper bounds on possible growth rates of certain sets of
positive integers $A_k=\{1= a_1 < a_2 < ... < a_{k}\}$ such that all integers
$n\in \{0, 1, 2, ..., ka_{k}\}$ can be represented as a sum of no more than $k$
elements of $A_k$, with repetition.


title: On tensor products of polynomial representations

abstract:
  We determine the necessary and sufficient combinatorial conditions for which
the tensor product of two irreducible polynomial representations of
$GL(n,\mathbb{C})$ is isomorphic to another. As a consequence we discover
families of Littlewood-Richardson coefficients that are non-zero, and a
condition on Schur non-negativity.


title: Quantum thermal transport from classical molecular dynamics

abstract:
  Using a generalized Langevin equation of motion, quantum ballistic thermal
transport is obtained from classical molecular dynamics. This is possible
because the heat baths are represented by random noises obeying quantum
Bose-Einstein statistics. The numerical method gives asymptotically exact
results in both the low-temperature ballistic transport regime and
high-temperature strongly nonlinear classical regime. The method can be thought
of as a semi-classical approximation to the quantum transport problem. A
one-dimensional quartic on-site model is used to demonstrate the crossover from
ballistic to diffusive thermal transport.


title:
Schur positivity of skew Schur function differences and applications to
  ribbons and Schubert classes

abstract:
  Some new relations on skew Schur function differences are established both
combinatorially using Sch\"utzenberger's jeu de taquin, and algebraically using
Jacobi-Trudi determinants. These relations lead to the conclusion that certain
differences of skew Schur functions are Schur positive. Applying these results
to a basis of symmetric functions involving ribbon Schur functions confirms the
validity of a Schur positivity conjecture due to McNamara. A further
application reveals that certain differences of products of Schubert classes
are Schubert positive.


title:
Numerical Linked-Cluster Algorithms. I. Spin systems on square,
  triangular, and kagome lattices

abstract:
  We discuss recently introduced numerical linked-cluster (NLC) algorithms that
allow one to obtain temperature-dependent properties of quantum lattice models,
in the thermodynamic limit, from exact diagonalization of finite clusters. We
present studies of thermodynamic observables for spin models on square,
triangular, and kagome lattices. Results for several choices of clusters and
extrapolations methods, that accelerate the convergence of NLC, are presented.
We also include a comparison of NLC results with those obtained from exact
analytical expressions (where available), high-temperature expansions (HTE),
exact diagonalization (ED) of finite periodic systems, and quantum Monte Carlo
simulations.For many models and properties NLC results are substantially more
accurate than HTE and ED.


title:
Numerical Linked-Cluster Algorithms. II. t-J models on the square
  lattice

abstract:
  We discuss the application of a recently introduced numerical linked-cluster
(NLC) algorithm to strongly correlated itinerant models. In particular, we
present a study of thermodynamic observables: chemical potential, entropy,
specific heat, and uniform susceptibility for the t-J model on the square
lattice, with J/t=0.5 and 0.3. Our NLC results are compared with those obtained
from high-temperature expansions (HTE) and the finite-temperature Lanczos
method (FTLM). We show that there is a sizeable window in temperature where NLC
results converge without extrapolations whereas HTE diverges. Upon
extrapolations, the overall agreement between NLC, HTE, and FTLM is excellent
in some cases down to 0.25t. At intermediate temperatures NLC results are
better controlled than other methods, making it easier to judge the convergence
and numerical accuracy of the method.


title: Dynamics of Alpha-Helix Formation in the CSAW Model

abstract:
  We study the folding dynamics of polyalanine (Ala$_{20}$), a protein fragment
with 20 residues whose native state is a single alpha helix. We use the CSAW
model (conditioned self-avoiding walk), which treats the protein molecule as a
chain in Brownian motion, with interactions that include hydrophobic forces and
internal hydrogen bonding. We find that large scale structures form before
small scale structures, and obtain the relevant relaxation times. We find that
helix nucleation occurs at two separate points on the protein chain. The
evolution of small and large scale structures involve different mechanisms.
While the former can be describe by rate equations governing the growth of
helical content, the latter is akin to the relaxation of an elastic solid.


title:
The Effects of Metallicity and AGN Activity on the Mid-Infrared Dust
  Emission of Galaxies

abstract:
  Using a sample of the $Spitzer$ SWIRE-field galaxies whose optical spectra
are taken from the Data Release 4 of the Sloan Digital Sky Survey, we study
possible correlations between the Mid-InfraRed (MIR) dust emission from these
galaxies and both their metallicities and AGN activities. We find that both
metallicity and AGN activity are well correlated with the following ratios:
PAH(Polycyclic Aromatic Hydrocarbon)-to-star, VSG(Very Small Grain)-to-star and
PAH-to-VSG, which can be characterized by $\nu L_{\nu}[8\mu m({\rm dust})]/\nu
L_{\nu}[3.6\mu m]$, $\nu L_{\nu}[24\mu m]/\nu L_{\nu}[3.6\mu m]$, and$\nu
L_{\nu}[8\mu m({\rm dust})]/\nu L_{\nu}[24\mu m]$ respectively. We argue that
our MIR-metallicity correlation could be explained by either the amount of dust
(ongoing dust formation) or dust destruction (PAHs and VSGs could be destroyed
by hard and intense radiation fields), and that the MIR-AGN correlation could
arise due to either PAH destruction or an enhanced VSG continuum by the central
AGN.


title: Strangeness in the Nucleon

abstract:
  There are several different experimental indications, such as the strangeness
contribution to the magnetic moment of the proton, sigma_{\pi N} term, strange
spin polarization, ratio of strange and non strange quark flavor distributions
which suggest that the nucleon contains a hidden strangeness component which is
contradictory to the naive constituent quark model. Chiral constituent quark
model with configuration mixing (\chiCQM_{{\rm config}}) is known to provide a
satisfactory explanation of the ``proton spin problem'' and related issues. In
the present work, we have extended the model to carry out the calculations for
the parameters pertaining to the strange quark content of the nucleon, for
example, the strange spin polarization \Delta s, strange components of the weak
axial vector form factors \Delta \Sigma and \Delta_8 as well as F and D,
strangeness magnetic moment of the proton \mu_p^s, the strange quark content in
the nucleon f_s coming from the \sigma_{\pi N} term, the ratios between strange
and non-strange quarks \frac{2 s}{u+d} and \frac{2 s}{\bar u+ \bar d},
contribution of strangeness to angular momentum sum rule etc.. Our result
demonstrates the broad consistency with the experimental observations as well
as other theoretical considerations.


title:
Searching for a Companion Star of Tycho's Type Ia Supernova with Optical
  Spectroscopic Observations

abstract:
  We report our first results of photometric and spectroscopic observations for
Tycho's supernova remnant (SNR Tycho) to search for the companion star of a
type Ia supernova (SN Ia). From photometric observations using Suprime-Cam on
the Subaru Telescope, we have picked up stars brighter than 22 mag (in
$V$-band) for spectroscopy, which are located within a circular region with the
radius of 30" around the center of SNR Tycho. If the ejecta of young supernova
remnants, such as SNR Tycho, have a sufficient amount of Fe I, we should be
able to detect absorption lines at 3720 \AA and 3860 \AA associated with
transitions from the ground state of Fe I in the spectrum of the companion
star. To identify the companion star of a SN Ia using these characteristic
absorption lines of Fe I, we made optical low-resolution spectroscopy of their
targets using FOCAS on the Subaru Telescope. In our spectroscopic observations,
we obtained spectra of 17 stars in the SNR Tycho region and compare them with
template stellar spectra. We detect significant absorption lines from two stars
at 3720 \AA. Since widths of their absorption lines are broad, it is likely
that the detected absorptions are due to Fe I in the expanding ejecta of SNR
Tycho. However, none of stars exhibits a clear red wing in the observed
profiles of the absorption, though a star in the background of the SNR should
show it. Hence, we suggest another interpretation that the detected absorption
lines might be caused by the peculiarity of stars. A star named Tycho(E) has
the absorption line at 3720 \AA and its projected position is close to the
center of SNR Tycho. Based on our observations, Tycho(E) is a new candidate as
the companion star of Tycho's supernova.


title:
A comparison of the strong lensing properties of the Sersic and the NFW
  profiles

abstract:
  We investigate the strong lensing properties of the Sersic profile as an
alternative to the NFW profile, focusing on applications to lens modelling of
clusters. Given an underlying Sersic dark matter profile, we study whether an
NFW profile can provide an acceptable fit to strong lensing constraints in the
form of single or multiple measured Einstein radii. We conclude that although
an NFW profile that fits the lensing constraints can be found in many cases,
the derived parameters may be biased. In particular, we find that for n~2,
which corresponds to massive clusters, the mass at r_200 of the best fit NFW is
overestimated (by a factor of ~2) and the concentration is very low (c~2). The
differences are important enough to warrant the inclusion of Sersic profile for
future analysis of strong lensing clusters.


title: Landau thermodynamic potential for BaTiO_3

abstract:
  In the paper, the description of the dielectric and ferroelectric properties
of BaTiO_3 single crystals using Landau thermodynamic potential is addressed.
Our results suggest that when using the sixth-power free energy expansion of
the thermodynamic potential, remarkably different values of the fourth-power
coefficient, \beta (the coefficient of P^4_i terms), are required to adequately
reproduce the nonlinear dielectric behavior of the paraelectric phase and the
electric field induced ferroelectric phase, respectively. In contrast, the
eighth-power expansion with a common set of coefficients enables a good
description for both phases at the same time. These features, together with the
data available in literature, strongly attest to the necessity of the
eighth-power terms in Landau thermodynamic potential of BaTiO_3. In addition,
the fourth-power coefficients, \beta and \xi (the coefficient of P^2_i P^2_j
terms), were evaluated from the nonlinear dielectric responses along [001],
[011], and [111] orientations in the paraelectric phase. Appreciable
temperature dependence was evidenced for both coefficients above T_C. Further
analysis on the linear dielectric response of the single domain crystal in the
tetragonal phase demonstrated that temperature dependent anharmonic
coefficients are also necessary for an adequate description of the dielectric
behavior in the ferroelectric phase. As a consequence, an eighth-power
thermodynamic potential, with some of the anharmonic coefficients being
temperature dependent, was proposed and compared with the existing potentials.
In general, the potential proposed in this work exhibits a higher quality in
reproducing the dielectric and ferroelectric properties of this prototypic
ferroelectric substance.


title: Zeta functions and topological entropy of the Markov-Dyck shifts

abstract:
  The Markov-Dyck shifts arise from finite directed graphs. An expression for
the zeta function of a Markov-Dyck shift is given. The derivation of this
expression is based on a formula in Keller (G. Keller, {\it Circular codes,
loop counting, and zeta-functions}, J. Combinatorial Theory {\bf 56} (1991),
pp. 75--83). For a class of examples that includes the Fibonacci-Dyck shift the
zeta functions and topological entropy ae determined.


title: A Blass-Sagan bijection on Eulerian equivalence classes

abstract:
  Following the treatment of Blass and Sagan, we present an algorithmic
bijection between the Eulerian equivalence classes of totally cyclic
orientations and the spanning trees without internal activity edges for a given
graph.


title:
Search for New Particles Leading to Z+jets Final States in $p\bar{p}$
  Collisions at $\sqrt{s}=1.96$ TeV

abstract:
  We present the results of a search for new particles that lead to a \Z boson
plus jets in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV using the Collider
Detector at Fermilab (CDF II). A data sample with a luminosity of 1.06 \ifb\
collected using \Z boson decays to $ee$ and $\mu\mu$ is used. We describe a
completely data-based method to predict the dominant background from
standard-model \Z+jet events. This method can be similarly applied to other
analyses requiring background predictions in multi-jet environments, as shown
when validating the method by predicting the background from $W$+jets in \ttbar
production. No significant excess above the background prediction is observed,
and a limit is set using a fourth generation quark model to quantify the
acceptance. Assuming $BR(b' \to b\Z) = 100%$ and using a leading-order
calculation of the $b'$ cross section, $b'$ quark masses below 268 $\gev/c^2$
are excluded at 95% confidence level.


title: Unbounded-error One-way Classical and Quantum Communication Complexity

abstract:
  This paper studies the gap between quantum one-way communication complexity
$Q(f)$ and its classical counterpart $C(f)$, under the {\em unbounded-error}
setting, i.e., it is enough that the success probability is strictly greater
than 1/2. It is proved that for {\em any} (total or partial) Boolean function
$f$, $Q(f)=\lceil C(f)/2 \rceil$, i.e., the former is always exactly one half
as large as the latter. The result has an application to obtaining (again an
exact) bound for the existence of $(m,n,p)$-QRAC which is the $n$-qubit random
access coding that can recover any one of $m$ original bits with success
probability $\geq p$. We can prove that $(m,n,>1/2)$-QRAC exists if and only if
$m\leq 2^{2n}-1$. Previously, only the construction of QRAC using one qubit,
the existence of $(O(n),n,>1/2)$-RAC, and the non-existence of
$(2^{2n},n,>1/2)$-QRAC were known.


title:
Quantization of the metric diagonal spacetime with Gaussian normal
  coordinates

abstract:
  In the analysis of the Wheeler-DeWitt equation, we have simplified the
Hamiltonian constraint of the Wheeler-DeWitt equation using the coordinate
transformation. The coordinate is choose such that metric becomes diagonal and
as Gaussian normal coordinate. Or we treat small universe so that the metric
become diagonal and universe is covered by Gaussian normal coordinates. We have
solved the Wheeler-DeWitt equation of such universes. Such that universe
contains Biancki I type universe or the black hole universe.


title:
Affine parts of abelian surfaces as complete intersection of three
  quartics

abstract:
  We consider an integrable system in five unknowns having three quartics
invariants. We show that the complex affine variety defined by putting these
invariants equal to generic constants, completes into an abelian surface; the
jacobian of a genus two hyperelliptic curve. This system is algebraic
completely integrable and it can be integrated in genus two hyperelliptic
functions.


title:
Detection of Neutron Scattering from Phase IV of Ce0.7La0.3B6: A
  Confirmation of the Octupole Order

abstract:
  We have performed a single crystal neutron scattering experiment on
Ce0.7La0.3B6 to investigate the order parameter of phase IV microscopically.
Below the phase transition temperature 1.5 K of phase IV, weak but distinct
superlattice reflections at the scattering vector (h/2,h/2,l/2) (h, l = odd
number) have been observed by neutron scattering for the first time. The
intensity of the superlattice reflections is stronger for high scattering
vectors, which is quite different from the usual magnetic form factor of
magnetic dipoles. This result directly evidences that the order parameter of
phase IV has a complex magnetization density, consistent with the recent
experimental and theoretical prediction in which the order parameter is the
magnetic octupoles Tbeta with Gamma5 symmetry of point group Oh. Neutron
scattering experiments using short wavelength neutrons, as done in this study,
could become a general method to study the high-rank multipoles in f electron
systems.


title: Experimental characterization of Gaussian quantum communication channels

abstract:
  We present a full experimental characterization of continuous variable
quantum communication channels established by shared entanglement together with
local operations and classical communication. The resulting teleportation
channel was fully characterized by measuring all elements of the covariance
matrix of the shared two-mode squeezed Gaussian state. From the experimental
data we determined the lower bound to the quantum channel capacity, the
teleportation fidelity of coherent states and the logarithmic negativity and
the purity of the shared state. Additionally, a positive secret key rate was
obtained for two of the established channels.


title:
Theory of Fulde-Ferrell-Larkin-Ovchinnikov state of superconductors with
  and without inversion symmetry: Hubbard model approach

abstract:
  We study Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state of superconductors
with and without inversion symmetry based on the Hubbard model on the square
lattice near half-filling, using the random phase approximation. We show that
center of mass momentum $Q$ tends to be parallel to $x$- or y-axis in the
presence of inversion symmetry, while $Q$ vector is likely to be perpendicular
to the magnetic field in the absence of inversion symmetry. We also clarify
that $d+f$-wave pairing is favored and the hetero spin triplet $f$-wave state
is present in the FFLO state unlike state in the superconductors only with the
Rashba type spin-orbit coupling (RSOC) originating from the broken inversion
symmetry. The triplet $f$-wave state is enhanced by magnetic field and the
RSOC. This stems from the reduction of the spin susceptibilities by the
magnetic field and the RSOC.


title: A cool R Coronae Borealis star Z UMi

abstract:
  The high resolution spectra of a R CrB type star Z UMi are analysed. The
atmospheric parameters of Z UMi are estimated: Teff=5250+/-250K and log
g=0.5+/-0.3. This places Z UMi among the coolest R CrB stars. The hydrogen
deficiency of Z UMi is confirmed. The abundances of other elements resemble
those found for the minority group of R CrB stars. We note very low iron
abundance, [Fe/H]=-1.85, and an excess of lithium, [Li/Fe]=+1.9.


title:
High redshift X-ray galaxy clusters. I. The impact of point sources on
  the cluster properties

abstract:
  The current generation of X-ray observatories like Chandra allows studies
with very fine spatial details. It is now possible to resolve X-ray point
sources projected into the cluster diffuse emission and exclude them from the
analysis to estimate the ``correct'' X-ray observables. In order to verify the
incidence of point sources on the cluster thermal emission and to evaluate the
impact of their non-thermal emission on the determination of cluster
properties, we used a sample of 18 high-z (0.25 < z < 1.01) clusters from the
Chandra archive. We performed a detailed analysis of the cluster properties and
compared the changes observed in the X-ray observables, like temperature and
luminosity or their inter-relation, when one keeps the point sources in the
analysis. The point sources projected into the cluster extended emission affect
the estimates of cluster temperature or luminosity considerably (up to 13% and
17% respectively). These percentages become even larger for clusters with z >
0.7 where temperature and luminosity increase up to 24% and 22%, respectively.
Thus the point sources should be removed to correctly estimate the cluster
properties. However the inclusion of the point sources does not impact
significantly the slope and normalization of the L-T relationship since for
each cluster the correction to be applied to T and L produces a moderate shift
in the L-T plane almost parallel to the best-fit of the ``correct'' L-T
relation.


title:
Orientations, lattice polytopes, and group arrangements I: Chromatic and
  tension polynomials of graphs

abstract:
  This is the first one of a series of papers on association of orientations,
lattice polytopes, and abelian group arrangements to graphs. The purpose is to
interpret the integral and modular tension polynomials of graphs at zero and
negative integers. The whole exposition is put under the framework of subgroup
arrangements and the application of Ehrhart polynomials. Such viewpoint leads
to the following main results of the paper: (i) the reciprocity law for
integral tension polynomials; (ii) the reciprocity law for modular tension
polynomials; and (iii) a new interpretation for the value of the Tutte
polynomial $T(G;x,y)$ of a graph $G$ at $(1,0)$ as the number of
cut-equivalence classes of acyclic orientations on $G$.