title:
The cross-correlation of the CMB polarisation and the 21-cm line
  fluctuations from cosmic reionisation

abstract:
  The cosmic microwave background (CMB) polarisation and the 21 cm line
fluctuations are powerful probes of cosmological reionisation. We study how the
cross-correlation between the CMB polarisation (E-modes) and the 21 cm line
fluctuations can be used to gain further understanding of the reionisation
history, within the framework of inhomogeneous reionisation. Since the E-mode
polarisation reflects the amplitude of the quadrupole component of the CMB
temperature fluctuations, the angular power spectrum of the cross-correlation
exhibits oscillations at all multipoles. The first peak of the power spectrum
appears at the scale corresponding to the quadrupole at the redshift that is
probed by the 21 cm line fluctuations. The peak reaches its maximum value in
redshift when the average ionisation fraction of the universe is about half. On
the other hand, on small scales, there is a damping that depends on the
duration of reionisation. Thus, the cross-correlation between the CMB
polarisation and the 21 cm line fluctuations has the potential to constrain
accurately the epoch and the duration of reionisation.


title: Pattern formation in mixtures of ultracold atoms in optical lattices

abstract:
  Regular pattern formation is ubiquitous in nature; it occurs in biological,
physical, and materials science systems. Here we propose a set of experiments
with ultracold atoms that show how to examine different types of pattern
formation. In particular, we show how one can see the analog of labyrinthine
patterns (so-called quantum emulsions) in mixtures of light and heavy atoms
(that tend to phase separate) by tuning the trap potential and we show how
complex geometrically ordered patterns emerge (when the mixtures do not phase
separate), which could be employed for low-temperature thermometry. The complex
physical mechanisms for the pattern formation at zero temperature are
understood within a theoretical analysis called the local density
approximation.


title: Complexity Metrics for Spreadsheet Models

abstract:
  Several complexity metrics are described which are related to logic
structure, data structure and size of spreadsheet models. They primarily
concentrate on the dispersion of cell references and cell paths. Most metrics
are newly defined, while some are adapted from traditional software
engineering. Their purpose is the identification of cells which are liable to
errors. In addition, they can be used to estimate the values of dependent
process metrics, such as the development duration and effort, and especially to
adjust the cell error rate in accordance with the contents of each individual
cell, in order to accurately asses the reliability of a model. Finally, two
conceptual constructs - the reference branching condition cell and the
condition block - are discussed, aiming at improving the reliability,
modifiability, auditability and comprehensibility of logical tests.


title: Optimal tracking for pairs of qubit states

abstract:
  In classical control theory, tracking refers to the ability to perform
measurements and feedback on a classical system in order to enforce some
desired dynamics. In this paper we investigate a simple version of quantum
tracking, namely, we look at how to optimally transform the state of a single
qubit into a given target state, when the system can be prepared in two
different ways, and the target state depends on the choice of preparation. We
propose a tracking strategy that is proved to be optimal for any input and
target states. Applications in the context of state discrimination, state
purification, state stabilization and state-dependent quantum cloning are
presented, where existing optimality results are recovered and extended.


title:
Consistency test of general relativity from large scale structure of the
  Universe

abstract:
  We construct a consistency test of General Relativity (GR) on cosmological
scales. This test enables us to distinguish between the two alternatives to
explain the late-time accelerated expansion of the universe, that is, dark
energy models based on GR and modified gravity models without dark energy. We
derive the consistency relation in GR which is written only in terms of
observables - the Hubble parameter, the density perturbations, the peculiar
velocities and the lensing potential. The breakdown of this consistency
relation implies that the Newton constant which governs large-scale structure
is different from that in the background cosmology, which is a typical feature
in modified gravity models. We propose a method to perform this test by
reconstructing the weak lensing spectrum from measured density perturbations
and peculiar velocities. This reconstruction relies on Poisson's equation in GR
to convert the density perturbations to the lensing potential. Hence any
inconsistency between the reconstructed lensing spectrum and the measured
lensing spectrum indicates the failure of GR on cosmological scales. The
difficulties in performing this test using actual observations are discussed.


title: Constraining Inflation

abstract:
  Slow roll reconstruction is derived from the Hamilton-Jacobi formulation of
inflationary dynamics. It automatically includes information from sub-leading
terms in slow roll, and facilitatesthe inclusion of priors based on the
duration on inflation. We show that at low inflationary scales the
Hamilton-Jacobi equations simplify considerably. We provide a new
classification scheme for inflationary models, based solely on the number of
parameters needed to specify the potential, and provide forecasts for likely
bounds on the slow roll parameters from future datasets. A minimal running of
the spectral index, induced solely by the first two slow roll parameters
(\epsilon and \eta) appears to be effectively undetectable by realistic Cosmic
Microwave Background experiments. However, we show that the ability to detect
this signal increases with the lever arm in comoving wavenumber, and we
conjecture that high redshift 21 cm data may allow tests of second order
consistency conditions on inflation. Finally, we point out that the second
order corrections to the spectral index are correlated with the inflationary
scale, and thus the amplitude of the CMB B-mode.


title:
The orbital poles of Milky Way satellite galaxies: a rotationally
  supported disc-of-satellites

abstract:
  Available proper motion measurements of Milky Way (MW) satellite galaxies are
used to calculate their orbital poles and projected uncertainties. These are
compared to a set of recent cold dark-matter (CDM) simulations, tailored
specifically to solve the MW satellite problem. We show that the CDM satellite
orbital poles are fully consistent with being drawn from a random distribution,
while the MW satellite orbital poles indicate that the disc-of-satellites of
the Milky Way is rotationally supported. Furthermore, the bootstrapping
analysis of the spatial distribution of theoretical CDM satellites also shows
that they are consistent with being randomly drawn. The theoretical CDM
satellite population thus shows a significantly different orbital and spatial
distribution than the MW satellites, most probably indicating that the majority
of the latter are of tidal origin rather than being DM dominated
sub-structures. A statistic is presented that can be used to test a possible
correlation of satellite galaxy orbits with their spatial distribution.


title:
Infinite randomness fixed point of the superconductor-metal quantum
  phase transition

abstract:
  We examine the influence of quenched disorder on the superconductor-metal
transition, as described by a theory of overdamped Cooper pairs which repel
each other. The self-consistent pairing eigenmodes of a quasi-one dimensional
wire are determined numerically. Our results support the recent proposal by
Hoyos et al. (arXiv:0705.1865) that the transition is characterized by the same
strong disorder fixed point describing the onset of ferromagnetism in the
random quantum Ising chain in a transverse field.


title:
Frequency and Impact of Galaxy Mergers and Interactions over the last 7
  Gyr

abstract:
  We explore the history and impact of galaxy mergers and interactions over
z~0.24 to 0.80, based on HST ACS, Combo-17, and Spitzer 24 mu data of ~4500
galaxies in the GEMS survey. Using visual and quantitative parameters,we
identify galaxies with strong distortions indicative of recent strong
interactions and mergers versus normal galaxies (E/S0, Sa, Sb-Sc, Sd/Irr). Our
results are: (1) The observed fraction F of strongly disturbed systems among
high mass (M>=2.5E10 Msun) galaxies is ~9% to 12% in every Gyr bin over z~0.24
to 0.80. The corresponding merger rate is a few times 10^-4 galaxies Gyr-1
Mpc-3. The fraction F shows fair agreement with the merger fraction of mass
ratio >=1:10 predicted by several LCDM-based simulations. (2) For M>=1E9 Msun
systems, the average star formation rate (SFR) of strongly disturbed systems is
only modestly enhanced with respect to normal galaxies, in agreement with
recent simulations. In fact, over z~0.24 to 0.80, strongly disturbed systems
only account for a small fraction (<~30%) of the total SFR density. This
suggests that the behaviour of the cosmic SFR density over the last seven
billion years is predominantly shaped by normal galaxies.


title: Electronic and optical properties of electromigrated molecular junctions

abstract:
  Electromigrated nanoscale junctions have proven very useful for studying
electronic transport at the single-molecule scale. However, confirming that
conduction is through precisely the molecule of interest and not some
contaminant or metal nanoparticle has remained a persistent challenge,
typically requiring a statistical analysis of many devices. We review how
transport mechanisms in both purely electronic and optical measurements can be
used to infer information about the nanoscale junction configuration. The
electronic response to optical excitation is particularly revealing. We briefly
discuss surface-enhanced Raman spectroscopy on such junctions, and present new
results showing that currents due to optical rectification can provide a means
of estimating the local electric field at the junction due to illumination.


title: Constraining Galaxy Evolution With Bulge-Disk-Bar Decomposition

abstract:
  Structural decomposition of galaxies into bulge, disk, and bar components is
important to address a number of scientific problems. Measuring bulge, disk,
and bar structural parameters will set constraints on the violent and secular
processes of galaxy assembly and recurrent bar formation and dissolution
models. It can also help to quantify the fraction and properties of bulgeless
galaxies (those systems having no bulge or only a relatively insignificant
disky-pseudobulges), which defy galaxy formation paradigms requiring almost
every disk galaxy to have a classical bulge at its core. We demonstrate a proof
of concept and show early results of our ongoing three-component bulge-disk-bar
decomposition of NIR images for a sample of three complementary samples
spanning different epochs and different environments (field and cluster). In
contrast to most early studies, which only attempt two-component bulge-disk
decomposition, we fit three components using GALFIT: a bulge, a disk, and a
bar. We show that it is important to include the bar component, as this can
significantly lower the bulge-to-total luminosity ratio (B/T), in many cases by
a factor of two or more, thus effectively changing the Hubble type of a galaxy
from early to late.


title: The mass-metallicity relation of interacting galaxies

abstract:
  We study the mass-metallicity relation of galaxies in pairs and in isolation
taken from the SDSS-DR4 using the stellar masses and oxygen abundances derived
by Tremonti et al. (2004). Close galaxy pairs, defined by projected separation
r_p < 25kpc/h and radial velocity Delta_V < 350 km/s, are morphologically
classified according to the strength of the interaction signs. We find that
only for pairs showing signs of strong interactions, the mass-metallicity
relation differs significantly from that of galaxies in isolation. In such
pairs, the mean gas-phase oxygen abundances of galaxies with low stellar masses
(Mstar ~< 10^9 Msun/h) exhibit an excess of 0.2 dex. Conversely, at larger
masses (Mstar >~ 10^10 Msun/h) galaxies have a systematically lower
metallicity, although with a smaller difference (-0.05 dex). Similar trends are
obtained if g-band magnitudes are used instead of stellar masses. In minor
interactions, we find that the less massive member is systematically enriched,
while a galaxy in interaction with a comparable stellar mass companion shows a
metallicity decrement with respect to galaxies in isolation. We argue that
metal-rich starbursts triggered by a more massive component, and inflows of low
metallicity gas induced by comparable or less massive companion galaxies,
provide a natural scenario to explain our findings.


title: A note on Gribov copies in 3D Chern-Simons theory

abstract:
  Using powerful tools of harmonic maps and integrable systems, all the Gribov
copies in the Coulomb gauge in 3D Chern-Simons theory are constructed. Some
issues about the Gribov and the modular re- gions are shortly discussed. The
Gribov copies of the vacuum in 3D QCD in the Coulomb gauge are described. An
interesting implication of the presence of Gribov copies is briefy pointed out.


title:
Flavor Physics in SO(10) GUTs with Suppressed Proton decay Due to Gauged
  Discrete Symmetry

abstract:
  Generic SO(10) GUT models suffer from the problem that Planck scale induced
non-renormalizable proton decay operators require extreme suppression of their
couplings to be compatible with present experimental upper limits. One way to
resolve this problem is to supplement SO(10) by simple gauged discrete
symmetries which can also simultaneously suppress the renormalizable R-parity
violating ones when they occur and make the theory "more natural". Here we
discuss the phenomenological viability of such models. We first show that for
both classes of models, e.g the ones that use ${\bf 16}_H$ or ${\bf 126}_H$ to
break B-L symmetry, the minimal Higgs content which is sufficient for proton
decay suppression is inadequate for explaining fermion masses despite the
presence of all apparently needed couplings. We then present an extended ${\bf
16}_H$ model, with three {\bf 10} and three {\bf 45}-Higgs, where is free of
this problem. We propose this as a realistic and "natural" model for fermion
unification and discuss the phenomenology of this model e.g. its predictions
for neutrino mixings and lepton flavor violation.


title: Fast beam stacking using RF barriers

abstract:
  Two barrier RF systems were fabricated, tested and installed in the Fermilab
Main Injector. Each can provide 8 kV rectangular pulses (the RF barriers) at 90
kHz. When a stationary barrier is combined with a moving barrier, injected
beams from the Booster can be continuously deflected, folded and stacked in the
Main Injector, which leads to doubling of the beam intensity. This paper gives
a report on the beam experiment using this novel technology.


title:
Morphological Transformations of Galaxies in the A901/02 Supercluster
  from STAGES

abstract:
  We present a study of galaxies in the Abell 901/902 Supercluster at z~0.165,
based on HST ACS F606W, COMBO-17, Spitzer 24um, XMM-Newton X-ray, and
gravitational lensing maps, as part of the STAGES survey. We characterize
galaxies with strong externally-triggered morphological distortions and normal
relatively undisturbed galaxies, using visual classification and quantitative
CAS parameters. We compare normal and distorted galaxies in terms of their
frequency, distribution within the cluster, star formation properties, and
relationship to dark matter (DM) or surface mass density, and intra-cluster
medium (ICM) density. We revisit the morphology density relation, which
postulates a higher fraction of early type galaxies in dense environments, by
considering separately galaxies with a low bulge-to-disk (B/D) ratio and a low
gas content as these two parameters may not be correlated in clusters. We
report here on our preliminary analysis.


title: Update of eta-eta' mixing from J/psi->VP decays

abstract:
  The $\eta$-$\eta^\prime$ mixing angle is deduced from an updated
phenomenological analysis of $J/\psi$ decays into a vector and a pseudoscalar
meson. Corrections due to non-ideal $\omega$-$\phi$ mixing are confirmed to be
crucial to find $\theta_P=(-16.9\pm 1.7)^\circ$, in agreement with most recent
analyses. The newly reported values of $B(J/\psi\to\rho\pi)$ by the BABAR and
BES Collaborations make more difficult a reasonable description of data.


title: Characterizing Barred Galaxies in the Abell 901/902 Supercluster

abstract:
  In dense clusters, higher densities at early epochs as well as physical
processes, such as ram pressure stripping and tidal interactions become
important, and can have direct consequences for the evolution of bars and their
host disks. To study bars and disks as a function of environment, we are using
the STAGES ACS HST survey of the Abell 901/902 supercluster (z~0.165), along
with earlier field studies based the SDSS and the Ohio State University Bright
Spiral Galaxy Survey (OSUBSGS). We explore the limitations of traditional
methods for characterizing the bar fraction, and in particular highlight
uncertainties in disk galaxy selection in cluster environments. We present an
alternative approach for exploring the proportion of bars, and investigate the
properties of bars as a function of host galaxy color, Sersic index, stellar
mass, star formation rate (SFR), specific SFR, and morphology.


title: Operational aspects of the Main Injector large aperture quadrupole (WQB)

abstract:
  A two-year Large Aperture Quadrupole (WQB) Project was completed in the
summer of 2006 at Fermilab. Nine WQBs were designed, fabricated and
bench-tested by the Technical Division. Seven of them were installed in the
Main Injector and the other two for spares. They perform well. The aperture
increase meets the design goal and the perturbation to the lattice is minimal.
The machine acceptance in the injection and extraction regions is increased
from 40pi to 60pi mm-mrad. This paper gives a brief report of the operation and
performance of these magnets.


title: Alignment Timescale of the Microquasar GRO J1655-40

abstract:
  The microquasar GRO J1655-40 has a black hole with spin angular momentum
apparently misaligned to the orbital plane of its companion star. We
analytically model the system with a steady state disc warped by Lense-Thirring
precession and find the timescale for the alignment of the black hole with the
binary orbit. We make detailed stellar evolution models so as to estimate the
accretion rate and the lifetime of the system in this state. The secondary can
be evolving at the end of the main sequence or across the Hertzsprung gap. The
mass-transfer rate is typically fifty times higher in the latter case but we
find that, in both cases, the lifetime of the mass transfer state is at most a
few times the alignment timescale. The fact that the black hole has not yet
aligned with the orbital plane is therefore consistent with either model. We
conclude that the system may or may not have been counter-aligned after its
supernova kick but that it is most likely to be close to alignment rather than
counteralignment now.


title: The Scattered Disk as the source of the Jupiter Family comets

abstract:
  The short period Jupiter family comets (JFCs) are thought to originate in the
Kuiper Belt; specifically, a dynamical subclass of the Kuiper Belt known as the
`scattered disk' is argued to be the dominant source of JFCs. However, the best
estimates from observational surveys indicate that this source may fall short
by more than two orders of magnitude the estimates obtained from theoretical
models of the dynamical evolution of Kuiper belt objects into JFCs. We
re-examine the scattered disk as a source of the JFCs and make a rigorous
estimate of the discrepancy. We find that the uncertainties in the dynamical
models combined with a change in the size distribution function of the
scattered disk at faint magnitudes (small sizes) beyond the current
observational limit offer a possible but problematic resolution to the
discrepancy. We discuss several other possibilities: that the present
population of JFCs is a large fluctuation above their long term average, that
larger scattered disk objects tidally break-up into multiple fragments during
close planetary encounters as their orbits evolve from the trans-Neptune zone
to near Jupiter, or that there are alternative source populations that
contribute significantly to the JFCs. Well-characterized observational
investigations of the Centaurs, objects that are transitioning between the
trans-Neptune Kuiper belt region and the inner solar system, can test the
predictions of the non-steady state and the tidal break-up hypotheses. The
classical and resonant classes of the Kuiper belt are worth re-consideration as
significant additional or alternate sources of the JFCs.


title: Bimodality in Damped Lyman alpha Systems

abstract:
  We report evidence for a bimodality in damped Ly systems (DLAs). Using [C II]
158 mu cooling rates, lc, we find a distribution with peaks at lc=10^-27.4 and
10^-26.6 ergs s^-1 H^-1 separated by a trough at lc^crit ~= lc < 10^-27.0 ergs
s^-1 H^-1. We divide the sample into low cool DLAs with lc < lc^crit and high
cool DLAs with lc > lc^crit and find the Kolmogorv-Smirnov probabilities that
velocity width, metallicity, dust-to-gas ratio, and Si II equivalent width in
the two subsamples are drawn from the same parent population are small. All
these quantities are significantly larger in the high cool population, while
the H I column densities are indistinguishable in the two populations. We find
that heating by X-ray and FUV background radiation is insufficient to balance
the cooling rates of either population. Rather, the DLA gas is heated by local
radiation fields. The rare appearance of faint, extended objects in the Hubble
Ultra Deep Field rules out in situ star formation as the dominant
star-formation mode for the high cool population, but is compatible with in
situ star formation as the dominant mode for the low cool population. Star
formation in the high cool DLAs likely arises in Lyman Break galaxies. We
investigate whether these properties of DLAs are analogous to the bimodal
properties of nearby galaxies. Using Si II equivalent width as a mass
indicator, we construct bivariate distributions of metallicity, lc, and areal
SFR versus the mass indicators. Tentative evidence is found for correlations
and parallel sequences, which suggest similarities between DLAs and nearby
galaxies. We suggest that the transition-mass model provides a plausible
scenario for the bimodality we have found. As a result, the bimodality in
current galaxies may have originated in DLAs.


title: GoArrays: highly dynamic and efficient microarray probe design

abstract:
  MOTIVATION: The use of oligonucleotide microarray technology requires a very
detailed attention to the design of specific probes spotted on the solid phase.
These problems are far from being commonplace since they refer to complex
physicochemical constraints. Whereas there are more and more publicly available
programs for microarray oligonucleotide design, most of them use the same
algorithm or criteria to design oligos, with only little variation. RESULTS: We
show that classical approaches used in oligo design software may be inefficient
under certain experimental conditions, especially when dealing with complex
target mixtures. Indeed, our biological model is a human obligate parasite, the
microsporidia Encephalitozoon cuniculi. Targets that are extracted from
biological samples are composed of a mixture of pathogen transcripts and host
cell transcripts. We propose a new approach to design oligonucleotides which
combines good specificity with a potentially high sensitivity. This approach is
original in the biological point of view as well as in the algorithmic point of
view. We also present an experimental validation of this new strategy by
comparing results obtained with standard oligos and with our composite oligos.
A specific E.cuniculi microarray will overcome the difficulty to discriminate
the parasite mRNAs from the host cell mRNAs demonstrating the power of the
microarray approach to elucidate the lifestyle of an intracellular pathogen
using mix mRNAs.


title:
A fast Bayesian approach to discrete object detection in astronomical
  datasets - PowellSnakes I

abstract:
  A new fast Bayesian approach is introduced for the detection of discrete
objects immersed in a diffuse background. This new method, called PowellSnakes,
speeds up traditional Bayesian techniques by: i) replacing the standard form of
the likelihood for the parameters characterizing the discrete objects by an
alternative exact form that is much quicker to evaluate; ii) using a
simultaneous multiple minimization code based on Powell's direction set
algorithm to locate rapidly the local maxima in the posterior; and iii)
deciding whether each located posterior peak corresponds to a real object by
performing a Bayesian model selection using an approximate evidence value based
on a local Gaussian approximation to the peak. The construction of this
Gaussian approximation also provides the covariance matrix of the uncertainties
in the derived parameter values for the object in question. This new approach
provides a speed up in performance by a factor of `hundreds' as compared to
existing Bayesian source extraction methods that use MCMC to explore the
parameter space, such as that presented by Hobson & McLachlan. We illustrate
the capabilities of the method by applying to some simplified toy models.
Furthermore PowellSnakes has the advantage of consistently defining the
threshold for acceptance/rejection based on priors which cannot be said of the
frequentist methods. We present here the first implementation of this technique
(Version-I). Further improvements to this implementation are currently under
investigation and will be published shortly. The application of the method to
realistic simulated Planck observations will be presented in a forthcoming
publication.


title:
Exploring the Impact of Galaxy Interactions over Seven Billion Years
  with CAS

abstract:
  We explore galaxy assembly over the last seven billion years by
characterizing "normal" galaxies along the Hubble sequence, against strongly
disturbed merging/interacting galaxies with the widely used CAS system of
concentration (C), asymmetry (A), and 'clumpiness' (S) parameters, as well as
visual classification. We analyze Hubble Space Telescope (HST) ACS images of
~4000 intermediate and high mass (> 10^9 solar masses) galaxies from the GEMS
survey, one of the largest HST surveys conducted to date in two filters. We
explore the effectiveness of the CAS criteria [A>S and A>~0.35] in separating
normal and strongly disturbed galaxies at different redshifts, and quantify the
recovery and contamination rate. We also compare the average star formation
rate and the cosmic star formation rate density as a function of redshift
between normal and interacting systems identified by CAS.


title: The Impact of HD Cooling on the Formation of the First Stars

abstract:
  We use numerical simulations to investigate the importance of HD formation
and cooling on the first generation of metal-free stars in a LCDM cosmology. We
have implemented and tested non-equilibrium HD chemistry in an adaptive mesh
refinement simulation code and applied it to two situations. (1) It is first
applied to the formation of 10^5 - 10^6 Msun halos which form in the absence of
any ionizing source. We show, in agreement with previous work, that HD cooling
is of only marginal importance for most halos; however, we find that for the
lowest mass halos, HD cooling can equal or surpass the H2 cooling rate. This
leads to a population of stars formed in halos with effective HD cooling that
are less massive by a factor of ~6 compared to halos dominated by H2 cooling.
(2) In the second part of the paper, we ionize the halos in order to explore
the impact of HD cooling in the presence of an ample population of free
electrons. This leads to cooler temperatures (due to the electron- catalyzed
production of H2) and somewhat lower resulting proto-stellar mass. Adding HD
chemistry lowers the temperature further, to the level of the CMB. We find that
HD cooling dominates over H2 cooling in the density range 10^2 cm^-3 to 10^6
cm^-3, but above this density, the temperature rises and H2 cooling dominates
again. Because of this, the accretion rate on to the protostar is almost the
same as in the H2 case (at least for accreted masses below 50-100 Msun),
therefore we argue that HD cooling in ionized halos will probably not result in
a population of significantly lower mass stars.


title: A Paradigm for Spreadsheet Engineering Methodologies

abstract:
  Spreadsheet engineering methodologies are diverse and sometimes
contradictory. It is difficult for spreadsheet developers to identify a
spreadsheet engineering methodology that is appropriate for their class of
spreadsheet, with its unique combination of goals, type of problem, and
available time and resources. There is a lack of well-organized, proven
methodologies with known costs and benefits for well-defined spreadsheet
classes. It is difficult to compare and critically evaluate methodologies. We
present a paradigm for organizing and interpreting spreadsheet engineering
recommendations. It systematically addresses the myriad choices made when
developing a spreadsheet, and explicitly considers resource constraints and
other development parameters. This paradigm provides a framework for
evaluation, comparison, and selection of methodologies, and a list of essential
elements for developers or codifiers of new methodologies. This paradigm
identifies gaps in our knowledge that merit further research.


title: Acceleration radiation and the Planck scale

abstract:
  A uniformly accelerating observer perceives the Minkowski vacuum state as a
thermal bath of radiation. We point out that this field-theory effect can be
derived, for any dimension higher than two, without actually invoking very high
energy physics. This supports the view that this phenomenon is robust against
Planck-scale physics and, therefore, should be compatible with any underlying
microscopic theory.


title: The commutants of certain Toeplitz operators on weighted Bergman spaces

abstract:
  For $\alpha>-1$, let $A^2_{\alpha}$ be the corresponding weighted Bergman
space of the unit ball in $\mathbb{C}^n$. For a bounded measurable function
$f$, let $T_f$ be the Toeplitz operator with symbol $f$ on $A^2_{\alpha}$. This
paper describes all the functions $f$ for which $T_f$ commutes with a given
$T_g$, where $g(z)=z_{1}^{L_1}... z_{n}^{L_n}$ for strictly positive integers
$L_1,..., L_n$, or $g(z)=|z_1|^{s_1}... |z_n|^{s_n}h(|z|)$ for non-negative
real numbers $s_1,..., s_n$ and a bounded measurable function $h$ on $[0,1)$.


title: Constrained Consensus

abstract:
  We present distributed algorithms that can be used by multiple agents to
align their estimates with a particular value over a network with time-varying
connectivity. Our framework is general in that this value can represent a
consensus value among multiple agents or an optimal solution of an optimization
problem, where the global objective function is a combination of local agent
objective functions. Our main focus is on constrained problems where the
estimate of each agent is restricted to lie in a different constraint set.
  To highlight the effects of constraints, we first consider a constrained
consensus problem and present a distributed ``projected consensus algorithm''
in which agents combine their local averaging operation with projection on
their individual constraint sets. This algorithm can be viewed as a version of
an alternating projection method with weights that are varying over time and
across agents. We establish convergence and convergence rate results for the
projected consensus algorithm. We next study a constrained optimization problem
for optimizing the sum of local objective functions of the agents subject to
the intersection of their local constraint sets. We present a distributed
``projected subgradient algorithm'' which involves each agent performing a
local averaging operation, taking a subgradient step to minimize its own
objective function, and projecting on its constraint set. We show that, with an
appropriately selected stepsize rule, the agent estimates generated by this
algorithm converge to the same optimal solution for the cases when the weights
are constant and equal, and when the weights are time-varying but all agents
have the same constraint set.


title: On Super-Planckian Fields at Sub-Planckian Energies

abstract:
  For a light scalar coupled to gravity, I study the gravitational backreaction
associated with large field variations. I show a generic obstruction in
sourcing a super-Planckian scalar profile without making the whole experiment
collapse into a black hole. In empty space the scalar variation obeys an
absolute bound, of order of the Planck scale. A Newtonian analysis suggests
that inside its sources the scalar can undergo arbitrarily large variations
without causing large gravitational backreactions. However the maximum
attainable \Delta \phi increases only logarithmically with the size of the
source. The bound straightforwardly generalizes to any number of dimensions,
and to moduli space-like cases, where it applies to the invariant length in
field space as measured by the kinetic metric.


title: A Toolkit for Scalable Spreadsheet Visualization

abstract:
  This paper presents a toolkit for spreadsheet visualization based on logical
areas, semantic classes and data modules. Logical areas, semantic classes and
data modules are abstract representations of spreadsheet programs that are
meant to reduce the auditing and comprehension effort, especially for large and
regular spreadsheets. The toolkit is integrated as a plug-in in the Gnumeric
spreadsheet system for Linux. It can process large, industry scale spreadsheet
programs in reasonable time and is tightly integrated with its host spreadsheet
system. Users can generate hierarchical and graph-based representations of
their spreadsheets. This allows them to spot conceptual similarities in
different regions of the spreadsheet, that would otherwise not fit on a screen.
As it is assumed that the learning effort for effective use of such a tool
should be kept low, we aim for intuitive handling of most of the tool's
functions.


title:
A refined Luecking's theorem and finite-rank products of Toeplitz
  operators

abstract:
  For any function $f$ in $L^{\infty}(\mathbb{D})$, let $T_f$ denote the
corresponding Toeplitz operator the Bergman space $A^2(\mathbb{D})$. A recent
result of D. Luecking shows that if $T_f$ has finite rank then $f$ must be the
zero function. Using a refined version of this result, we show that if all
except possibly one of the functions $f_1,..., f_{m}$ are radial and
$T_{f_1}... T_{f_m}$ has finite rank, then one of these functions must be zero.


title:
Stochastic Network Model of Receptor Cross-Talk Predicts Anti-Angiogenic
  Effects

abstract:
  Cancer invasion and metastasis depend on angiogenesis. The cellular processes
(growth, migration, and apoptosis) that occur during angiogenesis are tightly
regulated by signaling molecules. Thus, understanding how cells synthesize
multiple biochemical signals initiated by key external stimuli can lead to the
development of novel therapeutic strategies to combat cancer. In the face of
large amounts of disjoint experimental data generated from multitudes of
laboratories using various assays, theoretical signal transduction models
provide a framework to distill this vast amount of data. Such models offer an
opportunity to formulate and test new hypotheses, and can be used to make
experimentally verifiable predictions. This study is the first to propose a
network model that highlights the cross-talk between the key receptors involved
in angiogenesis, namely growth factor, integrin, and cadherin receptors. From
available experimental data, we construct a stochastic Boolean network model of
receptor cross-talk, and systematically analyze the dynamical stability of the
network under continuous-time Boolean dynamics with a noisy production
function. We find that the signal transduction network exhibits a robust and
fast response to external signals, independent of the internal cell state. We
derive an input-output table that maps external stimuli to cell phenotypes,
which is extraordinarily stable against molecular noise with one important
exception: an oscillatory feedback loop between the key signaling molecules
RhoA and Rac1 is unstable under arbitrarily low noise, leading to erratic,
dysfunctional cell motion. Finally, we show that the network exhibits an
apoptotic response rate that increases with noise, suggesting that the
probability of programmed cell death depends on cell health.

categories: q-bio.MN cond-mat.dis-nn nlin.CG q-bio.QM


title: Kinematics in Matrix Gravity

abstract:
  We develop the kinematics in Matrix Gravity, which is a modified theory of
gravity obtained by a non-commutative deformation of General Relativity. In
this model the usual interpretation of gravity as Riemannian geometry is
replaced by a new kind of geometry, which is equivalent to a collection of
Finsler geometries with several Finsler metrics depending both on the position
and on the velocity. As a result the Riemannian geodesic flow is replaced by a
collection of Finsler flows. This naturally leads to a model in which a
particle is described by several mass parameters. If these mass parameters are
different then the equivalence principle is violated. In the non-relativistic
limit this also leads to corrections to the Newton's gravitational potential.
We find the first and second order corrections to the usual Riemannian geodesic
flow and evaluate the anomalous nongeodesic acceleration in a particular case
of static spherically symmetric background.


title: Non-Markovian Dynamics of Charge Carriers in Quantum Dots

abstract:
  We have investigated the dynamics of bound particles in multilevel
current-carrying quantum dots. We look specifically in the regime of resonant
tunnelling transport, where several channels are available for transport.
Through a non-Markovian formalism under the Born approximation, we investigate
the real-time evolution of the confined particles including transport-induced
decoherence and relaxation. In the case of a coherent superposition between
states with different particle number, we find that a Fock-space coherence may
be preserved even in the presence of tunneling into and out of the dot.
Real-time results are presented for various asymmetries of tunneling rates into
different orbitals.


title: Quark-nova remnants III:Application to RRATs

abstract:
  This is the third paper of a series of papers where we explore the evolution
of iron-rich ejecta from quark-novae. In the first paper, we explored the case
where a quark-nova ejecta forms a degenerate shell, supported by the star's
magnetic field, with applications to SGRs. In the second paper we considered
the case where the ejecta would have sufficient angular momentum to form a
degenerate Keplerian torus and applied such a system to two AXPs, namely 1E2259
+ 586 and 4U0142 + 615. Here we explore the late evolution of the degenerate
torus and find that it can remain unchanged for $\sim 10^{6}$ years before it
becomes non-degenerate. This transition from a degenerate torus (accretion
dominated) to a non-degenerate disk (no accretion), occurs about $10^{6}$ years
following the quark-nova, and exhibits features that are reminiscent of
observed properties of RRATs. Using this model, we can account for the duration
of both the radio bursts and the quiet phase, as well as the observed radio
flux from RRATs. The unique on and off activity of the radio pulsar PSR B1931 +
24 is similar to that of "old RRATs" in our model. For old RRATs, in our model,
the spin-down rate during the radio loud phase is about a factor 1.6 larger
than when it is quiet, remarkably similar to what has been measured for PSR
B1931 + 24. We discuss a connection between XDINs and RRATs and argue that some
XDINs may be ``dead RRATs'' that have already consumed their non-degenerate
disk.


title: Growth Gap vs. smoothness for diffeomorphisms of the interval

abstract:
  Given a diffeomorphism of the interval, consider the uniform norm of the
derivative of its n-th iteration. We get a sequence of real numbers called the
growth sequence. Its asymptotic behavior is an invariant which naturally
appears both in smooth dynamics and in geometry of the diffeomorphisms groups.
We find sharp estimates for the growth sequence of a given diffeomorphism in
terms of the modulus of continuity of its derivative. These estimates extend
previous results of Polterovich and Sodin, and Borichev.


title:
The Energetics of a Flaring Solar Active Region, and Observed Flare
  Statistics

abstract:
  A stochastic model for the energy of a flaring solar active region is
presented, generalising and extending the approach of Wheatland & Glukhov
(1998). The probability distribution for the free energy of an active region is
described by the solution to a master equation involving deterministic energy
input and random jump transitions downwards in energy (solar flares). It is
shown how two observable distributions, the flare frequency-energy distribution
and the flare waiting-time distribution, may be derived from the steady-state
solution to the master equation, for given choices for the energy input and for
the rates of flare transitions. An efficient method of numerical solution of
the steady-state master equation is presented. Solutions appropriate for
flaring, involving a constant rate of energy input and power-law distributed
jump transition rates, are numerically investigated. The flare-like solutions
exhibit power-law flare frequency-energy distributions below a high energy
rollover, set by the largest energy the active region is likely to have. The
solutions also exhibit approximately exponential (i.e. Poisson) waiting-time
distributions, despite the rate of flaring depending on the free energy of the
system.


title: The lipid bilayer at the mesoscale: a physical continuum model

abstract:
  We study a continuum model of the lipid bilayer based on minimizing the free
energy of a mixture of water and lipid molecules. This paper extends previous
work by Blom & Peletier (2004) in the following ways. (a) It formulates a more
physical model of the hydrophobic effect to facilitate connections with
microscale simulations. (b) It clarifies the meaning of the model parameters.
(c) It outlines a method for determining parameter values so that
physically-realistic bilayer density profiles can be obtained, for example for
use in macroscale simulations. Points (a)-(c) suggest that the model has
potential to robustly connect some micro- and macroscale levels of multiscale
blood flow simulations. The mathematical modelling in point (a) is based upon a
consideration of the underlying physics of inter-molecular forces. The
governing equations thus obtained are minimized by gradient flows via a novel
numerical approach; this enables point (b). The numerical results are shown to
behave physically in terms of the effect of background concentration, in
contrast to the earlier model which is shown here to not display the expected
behaviour. A "short-tail" approximation of the lipid molecules also gives an
analytical tool which yields critical values of some parameters under certain
conditions. Point (c) involves the first quantitative comparison of the
numerical data with physical experimental results.


title:
Dynamical systems gradient method for solving ill-conditioned linear
  algebraic systems

abstract:
  A version of the Dynamical Systems Method (DSM) for solving ill-conditioned
linear algebraic systems is studied in this paper. An {\it a priori} and {\it a
posteriori} stopping rules are justified. An algorithm for computing the
solution using a spectral decomposition of the left-hand side matrix is
proposed. Numerical results show that when a spectral decompositon of the
left-hand side matrix is available or not computationally expensive to obtain
the new method can be considered as an alternative to the Variational
Regularization.


title:
Stochastic Tamed 3D Navier-Stokes Equations: Existence, Uniqueness and
  Ergodicity

abstract:
  In this paper, we prove the existence of a unique strong solution to a
stochastic tamed 3D Navier-Stokes equation in the whole space as well as in the
periodic boundary case. Then, we also study the Feller property of solutions,
and prove the existence of invariant measures for the corresponding Feller
semigroup in the case of periodic conditions. Moreover, in the case of periodic
boundary and degenerated additive noise, using the notion of asymptotic strong
Feller property proposed by Hairer and Mattingly \cite{Ha-Ma}, we prove the
uniqueness of invariant measures for the corresponding transition semigroup.


title:
New phase transition in $Pr_{1-x}Ca_xMnO_3$ system: evidence for
  electrical polarization in charge ordered manganites

abstract:
  A detailed study of the electric field gradient (EFG) across the Pr1-xCaxMnO3
phase diagram and its temperature dependence is given. Clearly, distinct EFG
behaviours for samples outside/inside the charge order (CO) region are
observed. The EFG temperature dependence evidences a new phase transition
occurring over the broad CO region of the phase diagram. This transition is
discontinuous and occurs at temperatures between the charge ordering and the
Neel temperatures. The features observed in the EFG are associated with polar
atomic vibrations which eventually lead to a spontaneous local electric
polarization below CO transition.


title:
Magnetic field evolution of the quasiparticle interference in a d-wave
  superconductor

abstract:
  Quasiparticle interference in a d-wave superconductor with weak disorder
produces distinctive peaks in the Fourier-transformed local density of states
measured by scanning tunneling spectroscopy. We predict that amplitudes of
these peaks can be enhanced or suppressed by applied magnetic field according
to a very specific pattern governed by the symmetry of the superconducting
order parameter. This calculated pattern agrees with the recent experimental
measurement and suggests that the technique could be useful for probing the
underlying normal state at high fields.


title: Methods for measuring energy dissipation rate in anisotropic turbulence

abstract:
  Energy dissipation rate is an important parameter for nearly every experiment
on turbulent flow. Mathematically precise relationships between energy
dissipation rate and other measurable statistics for the case of anisotropic
turbulence are useful to experimentalists. Such relationships are obtained for
which the measurable statistics are the 3rd-order and 2nd-order velocity
structure functions as well as the acceleration-velocity structure function.
The relationships are derived using the Navier-Stokes equation without
approximation. Approximate versions are obtained on the basis of local
stationarity and local homogeneity. The latter are valid for arbitrary Reynolds
numbers for the case of stationary, homogeneous turbulence. Precise use of the
mathematics requires care noted in the Discussion section.


title:
Localization theorems in topological Hochschild homology and topological
  cyclic homology

abstract:
  We construct localization cofiber sequences for the topological Hochschild
homology (THH) and topological cyclic homology (TC) of spectral categories.
Using a global construction of the THH and TC of a scheme in terms of the
perfect complexes in a spectrally enriched version of the category of unbounded
complexes, the sequences specialize to localization cofiber sequences
associated to the inclusion of an open subscheme. These are the targets of the
cyclotomic trace from the localization sequence of Thomason-Trobaugh in
K-theory. We also deduce versions of Thomason's blow-up formula and the
projective bundle formula for THH and TC.


title: Using Layout Information for Spreadsheet Visualization

abstract:
  This paper extends a spreadsheet visualization technique by using layout
information. The original approach identifies logically or semantically related
cells by relying exclusively on the content of cells for identifying semantic
classes. A disadvantage of semantic classes is that users have to supply
parameters which describe the possible shapes of these blocks. The correct
parametrization requires a certain degree of experience and is thus not
suitable for untrained users. To avoid this constraint, the approach reported
in this paper uses row/column-labels as well as common format information for
locating areas with common, recurring semantics. Heuristics are provided to
distinguish between cell groups with intended common semantics and cell groups
related in an ad-hoc manner.


title: Spreadsheet Structure Discovery with Logic Programming

abstract:
  Our term "structure discovery" denotes the recovery of structure, such as the
grouping of cells, that was intended by a spreadsheet's author but is not
explicit in the spreadsheet. We are implementing structure discovery tools in
the logic-programming language Prolog for our spreadsheet analysis program
Model Master, by writing grammars for spreadsheet structures. The objective is
an "intelligent structure monitor" to run beside Excel, allowing users to
reconfigure spreadsheets to the representational needs of the task at hand.
This could revolutionise spreadsheet "best practice". We also describe a
formulation of spreadsheet reverse-engineering based on "arrows".


title: Generalized entanglement in static and dynamic quantum phase transitions

abstract:
  We investigate a class of one-dimensional, exactly solvable anisotropic XY
spin-1/2 models in an alternating transverse magnetic field from an
entanglement perspective. We find that a physically motivated Lie-algebraic
generalized entanglement measure faithfully portraits the static phase diagram
-- including second- and fourth-order quantum phase transitions belonging to
distinct universality classes. In the simplest time-dependent scenario of a
slow quench across a quantum critical point, we identify parameter regimes
where entanglement exhibits universal dynamical scaling relative to the static
limit.


title: Strichartz estimates on Schwarzschild black hole backgrounds

abstract:
  We study dispersive properties for the wave equation in the Schwarzschild
space-time. The first result we obtain is a local energy estimate. This is then
used, following the spirit of earlier work of Metcalfe-Tataru, in order to
establish global-in-time Strichartz estimates. A considerable part of the paper
is devoted to a precise analysis of solutions near the trapping region, namely
the photon sphere.


title: Hidden particle production at the ILC

abstract:
  In a class of new physics models, new physics sector is completely or partly
hidden, namely, singlet under the Standard Model (SM) gauge group. Hidden
fields included in such new physics models communicate with the Standard Model
sector through higher dimensional operators. If a cutoff lies in the TeV range,
such hidden fields can be produced at future colliders. We consider a scalar
filed as an example of the hidden fields. Collider phenomenology on this hidden
scalar is similar to that of the SM Higgs boson, but there are several features
quite different from those of the Higgs boson. We investigate productions of
the hidden scalar at the International Linear Collider (ILC) and study the
feasibility of its measurements, in particular, how well the ILC distinguishes
the scalar from the Higgs boson, through realistic Monte Carlo simulations.


title: Simulating the ISM in Global Disk Galaxies

abstract:
  Until recently, simulations that modeled entire galaxies were restricted to
an isothermal or fixed 2- or 3-phase interstellar medium (ISM). This obscured
the full role of the ISM in shaping the observed galactic-scale star formation
relations. In particular the Kennicutt relation suggests that star formation
rates depend in a simple way on global galactic quantities, such as mean gas
mass surface density and dynamical time. Contrary to this, observations of
nearby star-forming regions, including images from the Spitzer telescope, show
that all the way down to ``local-scales'' ($\sim$ parsecs) star formation is a
highly clustered process with the gas existing at a wide range of densities and
multiple phases, and seemingly decoupled from the larger-scale Galaxy. Many
different physical processes appear to be influencing the star formation rate,
including heating and cooling of the gas, ``turbulent'' energy injection from
outflows, winds and supernova blastwaves, ionization, and magnetic field
support. Here we present results from global simulations of disk galaxy star
formation that include a fully multiphase ISM and compare to simpler isothermal
models. We also investigate the effect of background heating. We discuss the
process of giant molecular cloud formation as one of the possible links between
the galactic and local scales of star formation.


title: Population imbalanced fermions in harmonically trapped optical lattices

abstract:
  The attractive Fermi-Hubbard Hamiltonian is solved via the Bogoliubov-de
Gennes formalism to analyze the ground state phases of population imbalanced
fermion mixtures in harmonically trapped two-dimensional optical lattices. In
the low density limit the superfluid order parameter modulates in the radial
direction towards the trap edges to accommodate the unpaired fermions that are
pushed away from the trap center with a single peak in their density. However
in the high density limit while the order parameter modulates in the radial
direction towards the trap center for low imbalance, it also modulates towards
the trap edges with increasing imbalance until the superfluid to normal phase
transition occurs beyond a critical imbalance. This leads to a single peak in
the density of unpaired fermions for low and high imbalance but leads to double
peaks for intermediate imbalance.


title: A Link between Binomial Parameters and Means of Bounded Random Variables

abstract:
  In this paper, we establish a fundamental connection between binomial
parameters and means of bounded random variables. Such connection finds
applications in statistical inference of means of bounded variables.


title:
El Roque de Los Muchachos Site Characteristics. III. Analysis of
  Atmospheric Dust and Aerosol Extinction

abstract:
  Canary Islands are normally interested by dominant North-East winds that, in
some meteorological conditions, can transport sand at high altitude from the
Sahara desert. The dust may affect the efficiency of the telescopes and
decreases the transparency of the sky. In order to maximize the scientific
return of the telescopes located at the ORM, we present an analysis of the
atmospheric dust content and its effects on astronomical observations. B, V and
I dust aerosol astronomical extinction are derived. Using a 5 years series
database of data taken from the four channel TNG dust monitor, we compute a
mean hourly and daily values of the dust content. We have detected particles
having size 0.3, 0.5, 1.0 and 5.0 um. Using a power law we have derived the
content of 10.0 um particles. We found a typical local dust concentration
ranging from 3x10^6 particles per cubic meter at 0.3 um, to 10^3 at 5.0 um and
10 at 10.0 um, increasing up to 3 order of magnitudes during the dust storms,
with a relative higher increase of 1.0, 5.0 and 10.0 um particles. The number
of local dust storm events is the same in winter- and summertime, but, the
average background and storm-related increases in the dust concentration in
summer are significantly higher than in winter. In a uniform approximation,
during the dust storms, an average height of the dust layer of 2.5 km above the
telescope is inferred. During the sand storms La Palma Island is affected by an
almost uniform layer extending up to 5 km above the sea level, down, at least
the height of the telescope. The visible extinction is dominated by particles
at 1.0, 5.0 and 10.0 um. In agreement with the results from Carlsberg Automatic
Meridian Circle (CAMC) we find a typical extinction during dust storms of about
0.2 mag/airmass.


title:
Generating functions for colored 3D Young diagrams and the
  Donaldson-Thomas invariants of orbifolds

abstract:
  We derive two multivariate generating functions for three-dimensional Young
diagrams (also called plane partitions). The variables correspond to a
colouring of the boxes according to a finite Abelian subgroup G of SO(3). We
use the vertex operator methods of Okounkov--Reshetikhin--Vafa for the easy
case G = Z/n; to handle the considerably more difficult case G=Z/2 x Z/2, we
will also use a refinement of the author's recent q--enumeration of pyramid
partitions.
  In the appendix, we relate the diagram generating functions to the
Donaldson-Thomas partition functions of the orbifold C^3/G. We find a
relationship between the Donaldson-Thomas partition functions of the orbifold
and its G-Hilbert scheme resolution. We formulate a crepant resolution
conjecture for the Donaldson-Thomas theory of local orbifolds satisfying the
Hard Lefschetz condition.


title: Adaptation dynamics of the quasispecies model

abstract:
  We study the adaptation dynamics of an initially maladapted population
evolving via the elementary processes of mutation and selection. The evolution
occurs on rugged fitness landscapes which are defined on the multi-dimensional
genotypic space and have many local peaks separated by low fitness valleys. We
mainly focus on the Eigen's model that describes the deterministic dynamics of
an infinite number of self-replicating molecules. In the stationary state, for
small mutation rates such a population forms a {\it quasispecies} which
consists of the fittest genotype and its closely related mutants. The
quasispecies dynamics on rugged fitness landscape follow a punctuated (or
step-like) pattern in which a population jumps from a low fitness peak to a
higher one, stays there for a considerable time before shifting the peak again
and eventually reaches the global maximum of the fitness landscape. We
calculate exactly several properties of this dynamical process within a
simplified version of the quasispecies model.


title: Belief Propagation and Loop Series on Planar Graphs

abstract:
  We discuss a generic model of Bayesian inference with binary variables
defined on edges of a planar graph. The Loop Calculus approach of [1, 2] is
used to evaluate the resulting series expansion for the partition function. We
show that, for planar graphs, truncating the series at single-connected loops
reduces, via a map reminiscent of the Fisher transformation [3], to evaluating
the partition function of the dimer matching model on an auxiliary planar
graph. Thus, the truncated series can be easily re-summed, using the Pfaffian
formula of Kasteleyn [4]. This allows to identify a big class of
computationally tractable planar models reducible to a dimer model via the
Belief Propagation (gauge) transformation. The Pfaffian representation can also
be extended to the full Loop Series, in which case the expansion becomes a sum
of Pfaffian contributions, each associated with dimer matchings on an extension
to a subgraph of the original graph. Algorithmic consequences of the Pfaffian
representation, as well as relations to quantum and non-planar models, are
discussed.


title: On bi-hamiltonian geometry of the Lagrange top

abstract:
  We consider three different incompatible bi-Hamiltonian structures for the
Lagrange top, which have the same foliation by symplectic leaves. These
bivectors may be associated with the different 2-coboundaries in the
Poisson-Lichnerowicz cohomology defined by canonical bivector on $e^*(3)$.


title: Delta Expansion on the Lattice and Dilated Scaling Region

abstract:
  A new kind of delta expansion is applied on the lattice to the d=2 non-linear
sigma model at N=infinity and N=1 which corresponds to the Ising model. We
introduce the parameter delta for the dilation of the scaling region of the
model with the replacement of the lattice spacing a to (1-delta)^{1/2}a. Then,
we demonstrate that the expansion in delta admits an approximation of the
scaling behavior of the model at both limits of N from the information at a
large lattice spacing a.


title: Super-Weyl invariance in 5D supergravity

abstract:
  We propose a superspace formulation for the Weyl multiplet of N=1 conformal
supergravity in five dimensions. The corresponding superspace constraints are
invariant under super-Weyl transformations generated by a real scalar
parameter. The minimal supergravity multiplet, which was introduced by Howe in
1981, emerges if one couples the Weyl multiplet to an Abelian vector multiplet
and then breaks the super-Weyl invariance by imposing the gauge condition W=1,
with W the field strength of the vector multiplet. The geometry of superspace
is shown to allow the existence of a large family of off-shell supermultiplets
that possess uniquely determined super-Weyl transformation laws and can be used
to describe supersymmetric matter. Many of these supermultiplets have not
appeared within the superconformal tensor calculus. We formulate a manifestly
locally supersymmetric and super-Weyl invariant action principle. In the
super-Weyl gauge W=1, this action reduces to that constructed in
arXiv:0712.3102. We also present a superspace formulation for the dilaton Weyl
multiplet.


title: Dirac particles tunneling from BTZ black hole

abstract:
  We calculated the Dirac Particles' Hawking radiation from the outer horizon
of BTZ black hole via tunneling formalism. Applying WKB approximation to the
Dirac equation in (2+1) dimensional BTZ spacetime background, we obtain the
radiation spectrum for fermions and Hawking temperature of BTZ black hole. The
results obtained by taking the fermion tunneling into account is consistent
with the previous literatures.


title: Multi-jet cross sections in charged current e+-p scattering at HERA

abstract:
  Jet cross sections were measured in charged current deep inelastic e+-p
scattering at high boson virtualities Q^2 with the ZEUS detector at HERA II
using an integrated luminosity of 0.36 fb^-1. Differential cross sections are
presented for inclusive-jet production as functions of Q^2, Bjorken x and the
jet transverse energy and pseudorapidity. The dijet invariant mass cross
section is also presented. Observation of three- and four-jet events in
charged-current e+-p processes is reported for the first time. The predictions
of next-to-leading-order (NLO) QCD calculations are compared to the
measurements. The measured inclusive-jet cross sections are well described in
shape and normalization by the NLO predictions. The data have the potential to
constrain the u and d valence quark distributions in the proton if included as
input to global fits.


title: The smallest singular value of a random rectangular matrix

abstract:
  We prove an optimal estimate on the smallest singular value of a random
subgaussian matrix, valid for all fixed dimensions. For an N by n matrix A with
independent and identically distributed subgaussian entries, the smallest
singular value of A is at least of the order \sqrt{N} - \sqrt{n-1} with high
probability. A sharp estimate on the probability is also obtained.


title:
Doppler imaging of the young late-type star LO Pegasi (BD +22 4409) in
  September 2003

abstract:
  A Doppler image of the ZAMS late-type rapidly rotating star LO Pegasi, based
on spectra acquired between 12 and 15 September 2003, is presented. The Least
Square Deconvolution technique is applied to enhance the signal-to-noise ratio
of the mean rotational broadened line profiles extracted from the observed
spectra. In the present application, a unbroadened spectrum is used as a
reference, instead of a simple line list, to improve the deconvolution
technique applied to extract the mean profiles. The reconstructed image is
similar to those previously obtained from observations taken in 1993 and 1998,
and shows that LO Peg photospheric activity is dominated by high-latitude spots
with a non-uniform polar cap. The latter seems to be a persistent feature as it
has been observed since 1993 with little modifications. Small spots, observed
between ~ 10 and ~ 60 degrees of latitude, appears to be different with respect
to those present in the 1993 and 1998 maps.


title: Subaru/MOIRCS Near-Infrared Imaging in the Proto-Cluster Region at z=3.1

abstract:
  We present the results of deep near-infrared imaging observations of the
z=3.1 proto-cluster region in the SSA22a field taken by MOIRCS mounted on the
Subaru Telescope. We observed a 21.7 arcmin^2 field to the depths of J=24.5,
H=24.3, and K=23.9 (5 sigma). We examine the distribution of the K-selected
galaxies at z~3 by using the simple color cut for distant red galaxies (DRGs)
as well as the photometric-redshift selection technique. The marginal density
excess of DRGs and the photo-z selected objects are found around the two most
luminous Ly alpha blobs (LABs). We investigate the correlation between the
K-selected objects and the LABs, and find that several galaxies with stellar
mass M_* = 10^9-10^11 M_solar exist in vicinity of LABs, especially around the
two most luminous ones. We also find that 7 of the 8 LABs in the field have
plausible K_s-band counterparts and the sum of the stellar mass possibly
associated with LABs correlates with the luminosity and surface brightness of
them, which implies that the origin of Ly alpha emission may be closely
correlated with their stellar mass or their previous star formation phenomena.


title: SIRENE: Supervised Inference of Regulatory Networks

abstract:
  Living cells are the product of gene expression programs that involve the
regulated transcription of thousands of genes. The elucidation of
transcriptional regulatory networks in thus needed to understand the cell's
working mechanism, and can for example be useful for the discovery of novel
therapeutic targets. Although several methods have been proposed to infer gene
regulatory networks from gene expression data, a recent comparison on a
large-scale benchmark experiment revealed that most current methods only
predict a limited number of known regulations at a reasonable precision level.
We propose SIRENE, a new method for the inference of gene regulatory networks
from a compendium of expression data. The method decomposes the problem of gene
regulatory network inference into a large number of local binary classification
problems, that focus on separating target genes from non-targets for each TF.
SIRENE is thus conceptually simple and computationally efficient. We test it on
a benchmark experiment aimed at predicting regulations in E. coli, and show
that it retrieves of the order of 6 times more known regulations than other
state-of-the-art inference methods.


title: Symmetry Breaking of Vortex Patterns in a Rotating Harmonic Potential

abstract:
  We numerically study the symmetry breaking instabilities of vortex patterns
in a rotating harmonic potential using a type of Ginzburg-Landau equation. The
configurations of vortex lattices change markedly by the symmetry-breaking
instabilities, and then, some vortices move away from the confinement
potential, which leads to the annihilation of vortices. The symmetry-breaking
instabilities and the instabilities of vortex nucleation determine the
parameter region of stable vortex patterns. We verify that the
symmetry-breaking instabilities also occur in a type of complex Ginzburg-Landau
equation.


title:
Bars in Local Galaxies: Evidence for a higher Optical Bar Fraction in
  Disk-Dominated Galaxies

abstract:
  We present a study of large-scale bars in the local Universe, based on a
large sample of ~3692 galaxies, with -18.5 <= M_g < -22.0 mag and redshift 0.01
<= z < 0.03, drawn from the SDSS. Our sample includes many galaxies that are
disk-dominated and of late Hubble types. Both color cuts and Sersic cuts yield
a similar sample of ~2000 disk galaxies. We characterize bars and disks by
ellipse-fitting r-band images and applying quantitative criteria. After
excluding highly inclined (>60 degrees) systems, we find the following results.
(1) The optical r-band fraction (f_opt-r) of barred galaxies is ~48%-52%. (2)
When galaxies are separated according to normalized half light radius
(r_e/R_24), a remarkable result is seen: f_opt-r rises sharply, from ~40% in
galaxies that have small r_e/R_24 and visually appear to host prominent bulges,
to ~70% for galaxies that have large r_e/R_24 and appear disk-dominated. (3)
f_opt-r rises for galaxies with bluer colors and higher central surface
brightness. A weaker rise is seen toward lower masses. (4) We find that ~20% of
our sample of disk galaxies appear to be ``quasi-bulgeless''. (5) If we
restrict our sample to bright galaxies and only consider bars that are strong
(ellipticity >=0.4) and large enough (semi-major axis >=1.5 kpc) to be reliably
characterized via ellipse-fitting out to z~0.8, we get an optical r-band
fraction for strong bars f_opt-s of ~34%. This value is higher only by a modest
factor of 1.4, compared to the value of ~24%+-4% reported at z~0.7-1.0. If one
assumes that the increasing obscuration by dust and star formation over z~0 to
1.0 causes a further artificial loss of bars, the data even allow for a
constant or rising fraction of strong bars with redshift.


title:
Selection rules for Brillouin light scattering from eigenvibrations of a
  sphere

abstract:
  Selection rules governing Brillouin light scattering from the vibrational
eigenmodes of a homogeneous, free-surface submicron sphere have been derived
using group theory. The derivation is for the condition where the sphere
diameter is of the order of the excitation light wavelength. Well-resolved
spectral data obtained from Brillouin light scattering from submicron silica
spheres provide experimental verification of the selection rules.


title:
Agmon's type estimates of exponential behavior of solutions of systems
  of elliptic partial differential equations.Applications to Schr\"{o}dinger,
  Moisil-Theodorescu and Dirac operators

abstract:
  The aim of this paper is to derive Agmon's type exponential estimates for
solutions of elliptic systems of partial differential equations on $\sR^n$. We
show that these estimates are related with the essential spectra of a family of
associated differential operators which depend on the original operator, and
with exponential weights which describe the decrease of solutions at infinity.
The essential spectra of the involved operators are described by means of their
limit operators. The obtained results are applied to study the problem of
exponential decay of eigenfunctions of matrix Schr\"{o}dinger,
Moisil-Theodorescu, and Dirac operators.


title:
A generalization of adjoint crystals for the quantized affine algebras
  of type $A\sb{n}\sp{(1)}$, $C\sb{n}\sp{(1)}$ and $D\sb{n+1}\sp{(2)}$

abstract:
  We propose to generalize Benkart-Frenkel-Kang-Lee's adjoint crystals and
describe their crystal structure for type $A\sb{n}\sp{(1)}$, $C\sb{n}\sp{(1)}$
and $D\sb{n+1}\sp{(2)}$.


title:
Enhancement of phonon effects in photoexcited states of one-dimensional
  Mott insulators

abstract:
  We examine how the electron correlation affects the electron-phonon (EP)
interaction in the linear optical absorption spectrum of the one-dimensional
(1D) extended Hubbard-Holstein model. A density matrix renormalization group
(DMRG) calculation shows that the effect of the EP interaction on an exciton is
enhanced by increasing the on-site Coulomb repulsion. This enhancement is in
contrast to the effect of the EP interaction on the ground state where the
Peierls instability is suppressed by the on-site Coulomb repulsion. The DMRG
data with the EP interaction fit with absorption experiments in 1D cuprates
better than those for the extended Hubbard model.


title: Renormalizability of a mofified generally covariant Yang-Mills action

abstract:
  A modified generally covariant Yang-Mills action, which depends on the
complex structure of spacetime and not its metric, is proved to be
renormalizable. This proof makes this Lagrangian model the unique known
generally covariant four dimensional model to be renormalizable without higher
order derivatives. The first order one-loop diagrams are computed in an
appropriate gauge condition and they are found to be finite.


title: Homogeneous cosmologies in generalized modified gravity

abstract:
  Dynamical system methods are used in the study of the stability of spatially
flat homogeneous cosmologies within a large class of generalized modified
gravity models in the presence of a relativistic matter-radiation fluid. The
present approach can be considered as the generalization of previous works in
which only $F(R)$ cases were considered. Models described by an arbitrary
function of all possible geometric invariants are investigated and general
equations giving all critical points are derived.


title:
Measurement of masses of the $\Xi_c(2645)$ and $\Xi_c(2815)$ baryons and
  observation of $\Xi_c(2980)\to\Xi_c(2645)\pi$ %and observation of the
  $\Xi_c(2980)$ and observation of $\Xi_c(2980)\to \Xi_c(2645)\pi$

abstract:
  We report a precise measurement of the masses of the $\Xi_c(2645)$ and
$\Xi_c(2815)$ baryons using a data sample of 414 fb$^{-1}$ collected by the
Belle collaboration at the KEKB $e^+ e^-$ collider. The states
$\Xi_c(2645)^{0,+}$ are observed in the $\Xi_c^{+,0}\pi^{-,+}$ decay modes,
while the $\Xi_c(2815)^{0,+}$ are reconstructed in the
$\Xi_c(2645)^{+,0}\pi^{-,+}$ decay modes. The following mass splittings are
determined: $m_{\Xi_c(2645)^+} - m_{\Xi_c(2645)^0} = (-0.1 \pm 0.3 ({\rm stat})
\pm 0.6 {(\rm syst})) {\rm MeV}/{\rm c}^2$ and $m_{\Xi_c(2815)^+} -
m_{\Xi_c(2815)^0} = (-3.4 \pm 1.9 ({\rm stat}) \pm 0.9 {(\rm syst})) {\rm
MeV}/{\rm c}^2$ with a much better precision than the current world averages.
We also observe a new decay mode, $\Xi_c(2980)^{0,+} \to
\Xi_c(2645)^{+,0}\pi^{-,+}$.


title:
A 24-h forecast of ozone peaks and exceedance levels using neural
  classifiers and weather predictions

abstract:
  A neural network combined to a neural classifier is used in a real time
forecasting of hourly maximum ozone in the centre of France, in an urban
atmosphere. This neural model is based on the MultiLayer Perceptron (MLP)
structure. The inputs of the statistical network are model output statistics of
the weather predictions from the French National Weather Service. With this
neural classifier, the Success Index of forecasting is 78% whereas it is from
65% to 72% with the classical MLPs. During the validation phase, in the Summer
of 2003, six ozone peaks above the threshold were detected. They actually were
seven.


title: Transient Binding and Dissipation in Semi-flexible Polymer Networks

abstract:
  While polymer solutions lack the mechanical stability only transiently
cross-linked networks can fulfill the competing requirements of structural
stability and maximal energy dissipation. Here, we show that transient
cross-links entail local stress relaxation and energy dissipation in an
intermediate elasticity dominated frequency regime. We quantify the mechanical
response of a semi-flexible polymer network by experimentally tuning the
off-rate of the transient cross-linker molecule and theoretically reproduce the
measured frequency response by a model that is predicated on microscopic
unbinding events.


title:
Superconductivity of bulk MgB2 + nano(n)-SiC composite system: A high
  field magnetization study

abstract:
  We study the effect of nano(n)-SiC addition on the crystal structure,
critical temperature (Tc), critical current density (Jc) and flux pinning in
MgB2 superconductor. X-ray diffraction patterns show that all the samples have
MgB2 as the main phase with very small amount of MgO, further with n-SiC
addition the presence of Mg2Si is also noted and confirmed by SEM & EDS. The Tc
value for the pure MgB2 is 18.9K under 8 Tesla applied field, while is 20.8K
for the 10-wt % n-SiC doped sample under the same field. This points towards
the increment in upper-critical field value with n-SiC addition. The
irreversibility field (Hirr) for the 5% n-SiC added sample reached 11.3, 10 and
5.8 Tesla, compared to 7.5, 6.5, and 4.2 Tesla for the pure MgB2 at 5, 10 and
20K respectively. The critical current density (Jc) for the 5-wt % n-SiC added
sample is increased by a factor of 35 at 10K and 6.5 Tesla field and by a
factor 20 at 20K and 4.2 Tesla field. These results are understood on the basis
of superconducting condensate (sigma band) disorder and ensuing intrinsic
pining due to B site C substitution clubbed with further external pinning due
to available n-SiC/Mg2Si pins in the composite system.


title:
Exotic quantum phase transitions in a Bose-Einstein condensate coupled
  to an optical cavity

abstract:
  A new extended Dicke model, which includes atom-atom interactions and a
driving classical laser field, is established for a Bose-Einstein condensate
inside an ultrahigh-finesse optical cavity. A feasible experimental setup with
a strong atom-field coupling is proposed, where most parameters are easily
controllable and thus the predicted second-order superradiant-normal phase
transition may be detected by measuring the ground-state atomic population.
More intriguingly, a novel second-order phase transition from the superradiant
phase to the \textquotedblleft Mott" phase is also revealed. In addition, a
rich and exotic phase diagram is presented.


title:
Plankton blooms in vortices: The role of biological and hydrodynamic
  time scales

abstract:
  We study the interplay of hydrodynamic mesoscale structures and the growth of
plankton in the wake of an island, and its interaction with a coastal
upwelling. Our focus is on a mechanism for the emergence of localized plankton
blooms in vortices. Using a coupled system of a kinematic flow mimicking the
mesoscale structures behind the island and a simple three component model for
the marine ecosystem, we show that the long residence times of nutrients and
plankton in the vicinity of the island and the confinement of plankton within
vortices are key factors for the appearance of localized plankton blooms

categories: nlin.CD physics.ao-ph physics.flu-dyn q-bio.PE


title:
Syntax diagrams as a formalism for representation of syntactic relations
  of formal languages

abstract:
  The new approach to representation of syntax of formal languages-- a
formalism of syntax diagrams is offered. Syntax diagrams look a convenient
language for the description of syntactic relations in the languages having
nonlinear representation of texts, for example, for representation of syntax
lows of the language of structural chemical formulas. The formalism of
neighbourhood grammar is used to describe the set of correct syntax constructs.
The neighbourhood the grammar consists of a set of families of
"neighbourhoods"-- the diagrams defined for each symbol of the language's
alphabet. The syntax diagram is correct if each symbol is included into this
diagram together with some neighbourhood. In other words, correct diagrams are
needed to be covered by elements of the neighbourhood grammar. Thus, the
grammar of formal language can be represented as system of the covers defined
for each correct syntax diagram.


title:
First-principles calculations of the vibrational properties of bulk CdSe
  and CdSe nanowires

abstract:
  We present first-principles calculations on bulk CdSe and CdSe nanowires with
diameters of up to 22 \AA. Density functional linear combination of atomic
orbitals and plane wave calculations of the electronic and structural
properties are presented and discussed. We use an iterative, symmetry-based
method to relax the structures into the ground state. We find that the band gap
depends on surface termination. Vibrational properties in the whole Brillouin
zone of bulk CdSe and the zone-center vibrations of nanowires are calculated
and analyzed. We find strongly size-dependent and nearly constant modes,
depending on the displacement directions. A comparison with available
experimental Raman data is be given.


title:
A molecular dynamics study of chemical gelation in a patchy particle
  model

abstract:
  We report event-driven molecular dynamics simulations of the irreversible
gelation of hard ellipsoids of revolution containing several associating
groups, characterizing how the cluster size distribution evolves as a function
of the extent of reaction, both below and above the gel point. We find that in
a very large interval of values of the extent of reaction, parameter-free
mean-field predictions are extremely accurate, providing evidence that in this
model the Ginzburg zone near the gel point, where non-mean field effects are
important, is very limited. We also find that the Flory's hypothesis for the
post-gelation regime properly describes the connectivity of the clusters even
if the long-time limit of the extent of reaction does not reach the fully
reacted state. This study shows that irreversibly aggregating asymmetric
hard-core patchy particles may provide a close realization of the mean-field
model, for which available theoretical predictions may help control the
structure and the connectivity of the gel state. Besides chemical gels, the
model is relevant to network-forming soft materials like systems with
bioselective interactions, functionalized molecules and patchy colloids.


title:
One Special Identity between the complete elliptic integrals of the
  first and the third kind

abstract:
  I prove an identity between the first kind and the third kind complete
elliptic integrals with the following form:
  $$\Pi({(1+x) (1-3 x)\over (1-x) (1+3 x)}, {(1+x)^3(1-3 x)\over (1-x)^3
(1+3x)})- {1+ 3 x \over 6 x} K ({(1+x)^3(1-3x)\over (1-x)^3 (1+3x)}) = 0, (0< x
< 1); =-{\pi\over 12} {(x-1)^{3/2}\sqrt{1+3 x}\over x} (x<0 or x>1).$$
  This relation can be applied to eliminate the complete elliptic integral of
the third kind from the analytic solutions of the imaginary part of two-loop
sunset diagrams in the equal mass case. The validity of this relation in the
complex domain is also briefly discussed.


title:
Sources of contamination to weak lensing three-point statistics:
  constraints from N-body simulations

abstract:
  We investigate the impact of the observed correlation between a galaxies
shape and its surrounding density field on the measurement of third order weak
lensing shear statistics. Using numerical simulations, we estimate the
systematic error contribution to a measurement of the third order moment of the
aperture mass statistic (GGG) from three-point intrinsic ellipticity
correlations (III), and the three-point coupling between the weak lensing shear
experienced by distant galaxies and the shape of foreground galaxies (GGI and
GII). We find that third-order weak lensing statistics are typically more
strongly contaminated by these physical systematics compared to second-order
shear measurements, contaminating the measured three-point signal for
moderately deep surveys with a median redshift z_m ~ 0.7 by ~ 15%. It has been
shown that accurate photometric redshifts will be crucial to correct for this
effect, once a model and the redshift dependence of the effect can be
accurately constrained. To this end we provide redshift-dependent fitting
functions to our results and propose a new tool for the observational study of
intrinsic galaxy alignments. For a shallow survey with z_m ~ 0.4 we find III to
be an order of magnitude larger than the expected cosmological GGG shear
signal. Compared to the two-point intrinsic ellipticity correlation which is
similar in amplitude to the two-point shear signal at these survey depths,
third order statistics therefore offer a promising new way to constrain models
of intrinsic galaxy alignments. Early shallow data from the next generation of
very wide weak lensing surveys will be optimal for this type of study.


title:
The diagonal and off-diagonal quark number susceptibility of high
  temperature and finite density QCD

abstract:
  We study the quark number susceptibility of the hot quark-gluon plasma at
zero and non-zero quark number density, using lattice Monte Carlo simulations
of an effective theory of QCD, electrostatic QCD (EQCD). Analytic continuation
is used to obtain results at non-zero quark chemical potential. We measure both
flavor singlet (diagonal) and non-singlet (off-diagonal) quark number
susceptibilities. The diagonal susceptibility approaches the perturbative
result above 20T_c, but below that temperature we observe significant
deviations. The results agree well with 4d lattice data down to temperatures
2T_c. The off-diagonal susceptibility is more prone to statistical and
systematic errors, but the results are consistent with perturbation theory
already at 10T_c.


title:
A deeper insight into quantum state transfer from an information flux
  viewpoint

abstract:
  We use the recently introduced concept of information flux in a many-body
register in order to give an alternative viewpoint on quantum state transfer in
linear chains of many spins.


title: The Levi Problem On Strongly Pseudoconvex $G$-Bundles

abstract:
  Let $G$ be a unimodular Lie group, $X$ a compact manifold with boundary, and
$M$ the total space of a principal bundle $G\to M\to X$ so that $M$ is also a
strongly pseudoconvex complex manifold. In this work, we show that if $G$ acts
by holomorphic transformations satisfying a local property, then the space of
square-integrable holomorphic functions on $M$ is infinite $G$-dimensional.


title:
FIGGS: Faint Irregular Galaxies GMRT Survey - Overview, observations and
  first results

abstract:
  The Faint Irregular Galaxies GMRT Survey (FIGGS) is a Giant Metrewave Radio
Telescope (GMRT) based HI imaging survey of a systematically selected sample of
extremely faint nearby dwarf irregular galaxies. The primary goal of FIGGS is
to provide a comprehensive and statistically robust characterization of the
neutral inter-stellar medium properties of faint, gas rich dwarf galaxies. The
FIGGS galaxies represent the extremely low-mass end of the dwarf irregular
galaxies population, with a median M${\rm{_B\sim-13.0}}$ and median HI mass of
$\sim 3 \times 10^7$ M$_\odot$, extending the baseline in mass and luminosity
space for a comparative study of galaxy properties. The HI data is supplemented
with observations at other wavelengths. In addition, distances accurate to ~
10% are available for most of the sample galaxies. This paper gives an
introduction to FIGGS, describe the GMRT observations and presents the first
results from the HI observations. From the FIGGS data we confirm the trend of
increasing HI to optical diameter ratio with decreasing optical luminosity; the
median ratio of D$_{\rm HI}$/D$_{\rm Ho}$ for the FIGGS sample is 2.4. Further,
on comparing our data with aperture synthesis surveys of bright spirals, we
find at best marginal evidence for a decrease in average surface density with
decreasing HI mass. To a good approximation the disks of gas rich galaxies,
ranging over 3 orders of magnitude in HI mass, can be described as being drawn
from a family with constant HI surface density.


title:
Towards the graviton from spinfoams: the complete perturbative expansion
  of the 3d toy model

abstract:
  We consider an exact expression for the 6j-symbol for the isosceles
tetrahedron, involving integrals over SU(2), and use it to write the two-point
function of 3d gravity on a single tetrahedron as a group integral. The
perturbative expansion of this expression is then performed with respect to the
boundary geometry using a simple saddle-point analysis. We derive the complete
expansion in inverse powers of the length scale and evaluate explicitly the
quantum corrections up to second order. Finally, we use the same method to
provide the complete expansion of the isosceles 6j-symbol with the explicit
phases at all orders and the next-to-leading correction to the Ponzano-Regge
asymptotics.


title:
Cationic Ordering and Microstructural Effects in the Ferromagnetic
  Perovskite La0.5Ba0.5CoO3: Impact upon Magnetotransport Properties

abstract:
  The synthesis and structural study of the stoichiometric perovskite
La0.5Ba0.5CoO3 have allowed three forms to be isolated. Besides the disordered
La0.5Ba0.5CoO3 and the perfectly ordered layered LaBaCo2O6, a third form called
nanoscale-ordered LaBaCo2O6, is obtained. As evidenced by transmission electron
microscopy investigations, the latter consists of 112-type 90 degree oriented
domains fitted into each other at a nanometer scale which induce large strains
and consequently local atomic scale lattice distortions. These three
ferromagnetic perovskites exhibit practically the same Tc (174-179 K), but
differently from the other phases, the nanoscale-ordered LaBaCo2O6 is a hard
ferromagnet, with Hc = 4.2 kOe, due to the strains which may pin domain walls,
preventing the reversal of the spins in a magnetic field. The magnetotransport
properties of these phases show that all of them exhibit a maximum intrinsic
magnetoresistance, close to 6-7 % around Tc under 70 kOe but that the ordered
phase exhibits a much higher tunnelling magnetoresistance effect at low
temperature of about 15 % against 4 % due to the grain boundary effects.


title:
2D Spectroscopy of Candidate Polar-Ring Galaxies: I. The Pair of
  Galaxies UGC 5600/09

abstract:
  Observations of the pair of galaxies VV 330 with the SCORPIO multimode
instrument on the 6-m Special Astrophysical Observatory telescope are
presented. Large-scale velocity fields of the ionized gas in H-alfa and
brightness distributions in continuum and H-alfa have been constructed for both
galaxies with the help of a scanning Fabry Perot interferometer. Long-slit
spectroscopy is used to study the stellar kinematics. Analysis of the data
obtained has revealed a complex structure in each of the pair components. Three
kinematic subsystems have been identified in UGC 5600: a stellar disk, an inner
gas ring turned with respect to the disk through ~80degrees, and an outer gas
disk. The stellar and outer gas disks are noncoplanar. Possible scenarios for
the formation of the observed multicomponent kinematic galactic structure are
considered, including the case where the large-scale velocity field of the gas
is represented by the kinematic model of a disk with a warp. The velocity field
in the second galaxy of the pair, UGC 5609, is more regular. A joint analysis
of the data on the photometric structure and the velocity field has shown that
this is probably a late-type spiral galaxy whose shape is distorted by the
gravitational interaction, possibly, with UGC 5600.


title:
Quench dynamics and defect production in the Kitaev and extended Kitaev
  models

abstract:
  We study quench dynamics and defect production in the Kitaev and the extended
Kitaev models. For the Kitaev model in one dimension, we show that in the limit
of slow quench rate, the defect density n \sim 1/\sqrt{\tau} where 1/\tau is
the quench rate. We also compute the defect correlation function by providing
an exact calculation of all independent non-zero spin correlation functions of
the model. In two dimensions, where the quench dynamics takes the system across
a critical line, we elaborate on the results of earlier work [K. Sengupta, D.
Sen and S. Mondal, Phys. Rev. Lett. 100, 077204 (2008)] to discuss the
unconventional scaling of the defect density with the quench rate. In this
context, we outline a general proof that for a d dimensional quantum model,
where the quench takes the system through a d-m dimensional gapless (critical)
surface characterized by correlation length exponent \nu and dynamical critical
exponent z, the defect density n \sim 1/\tau^{m \nu /(z \nu +1)}. We also
discuss the variation of the shape and the spatial extent of the defect
correlation function with the change of both the rate of quench and the model
parameters and compute the entropy generated during such a quench process.
Finally, we study the defect scaling law, entropy generation and defect
correlation function of the two-dimensional extended Kitaev model.


title: Study of in-medium $\omega$ meson properties in Ap, pA and AA collisions

abstract:
  We propose to investigate the in-medium properties of vector $\omega$ mesons
at the normal nuclear density in Ap(pA) collisions and at higher density in AA
collisions at the ITEP accelerator facility TWAC. Using of the inverse Ap
kinematics will permit us to study the $\omega$ meson production in a wide
momentum interval included the not yet explored range of small meson momenta
relative to the projectile nuclei where the mass modification effect in nuclear
matter is expected to be the strongest. Momentum dependence of the in-medium
$\omega$ meson width will be studied in the traditional pA kinematics. We
intend to use the electromagnetic calorimeter for reconstruction of the
$\omega$ meson invariant mass by detecting photons from the $\omega \to
\pi^{0}\gamma \to 3\gamma$ decay. The model calculations and simulations with
RQMD generator show feasibility of the proposed experiment. Available now
intensity of the ion beams provides a possibility to collect large statistics
and make decisive conclusion about the $\omega$ meson properties at density of
normal nuclei. At the second stage of the investigation the $\omega$ meson
properties will be studied in AA collisions at higher density. Interpretation
of these measurements will be based on the results obtained in Ap(pA)
interactions. Further investigation of the in-medium properties of light
unflavored and charmed mesons can be performed at ITEP and at GSI(FAIR) where
higher ion energies will be accessible in near future.


title: Signatures of new physics at 14 TeV

abstract:
  I give an overview of the ideas and of the problems that orient the
expectations for new physics at the Large Hadron Collider and, whenever I can,
I describe the corresponding signals.


title:
Modelling the Berezinskii-Kosterlitz-Thouless Transition in the
  NiGa_2S_4

abstract:
  In the two-dimensional superfluidity, the proliferation of the vortices and
the anti-vortices results in a new class of phase transition,
Berezinskii-Kosterlitz-Thouless (BKT) transition. This class of the phase
transitions is also anticipated in the two-dimensional magnetic systems.
However, its existence in the real magnetic systems still remains mysterious.
Here we propose a phenomenological model to illustrate that the novel
spin-freezing transition recently uncovered in the NMR experiment on the
NiGa_2S_4 compound is the BKT-type. The novel spin-freezing state observed in
the NiGa_2S_4 possesses the power-law decayed spin correlation.


title:
N-Dimensional non-abelian dilatonic, stable black holes and their
  Born-Infeld extension

abstract:
  We find large classes of non-asymptotically flat Einstein-Yang-Mills-Dilaton
(EYMD) and Einstein-Yang-Mills-Born-Infeld-Dilaton (EYMBID) black holes in
N-dimensional spherically symmetric spacetime expressed in terms of the
quasilocal mass. Extension of the dilatonic YM solution to N-dimensions has
been possible by employing the generalized Wu-Yang ansatz. Another metric
ansatz, which aided in finding exact solutions is the functional dependence of
the radius function on the dilaton field. These classes of black holes are
stable against linear radial perturbations. In the limit of vanishing dilaton
we obtain Bertotti-Robinson (BR) type metrics with the topology of
$AdS_{2}\times S^{N-2}.$ Since connection can be established between dilaton
and a scalar field of Brans-Dicke (BD) type we obtain black hole solutions also
in the Brans-Dicke-Yang-Mills (BDYM) theory as well.


title: Generalized Dirichlet normal ordering in open bosonic strings

abstract:
  Generally, open string boundary conditions play a nontrivial role in string
theory. For example, in the presence of an antisymmetric tensor background
field, they will lead the spacetime coordinates noncommutative. In this paper,
we mainly discuss how to build up a generalized Dirichlet normal ordered
product of open bosonic string embedding operators that satisfies both the
equations of motion and the generalized Dirichlet boundary conditions at the
quantum level in the presence of an antisymmetric background field, as the
generalized Neumann case has already been discussed in the literature. Further,
we also give a brief check of the consistency of the theory under the newly
introduced normal ordering.


title: Polynomial Filtering for Fast Convergence in Distributed Consensus

abstract:
  In the past few years, the problem of distributed consensus has received a
lot of attention, particularly in the framework of ad hoc sensor networks. Most
methods proposed in the literature address the consensus averaging problem by
distributed linear iterative algorithms, with asymptotic convergence of the
consensus solution. The convergence rate of such distributed algorithms
typically depends on the network topology and the weights given to the edges
between neighboring sensors, as described by the network matrix. In this paper,
we propose to accelerate the convergence rate for given network matrices by the
use of polynomial filtering algorithms. The main idea of the proposed
methodology is to apply a polynomial filter on the network matrix that will
shape its spectrum in order to increase the convergence rate. Such an algorithm
is equivalent to periodic updates in each of the sensors by aggregating a few
of its previous estimates. We formulate the computation of the coefficients of
the optimal polynomial as a semi-definite program that can be efficiently and
globally solved for both static and dynamic network topologies. We finally
provide simulation results that demonstrate the effectiveness of the proposed
solutions in accelerating the convergence of distributed consensus averaging
problems.