title: Dislocation-Mediated Melting in Superfluid Vortex Lattices

abstract:
  We describe thermal melting of the two-dimensional vortex lattice in a
rotating superfluid by generalizing the Halperin and Nelson theory of
dislocation-mediated melting. and derive a melting temperature proportional to
the renormalized shear modulus of the vortex lattice. The rigid-body rotation
of the superfluid attenuates the effects of lattice compression on the energy
of dislocations and hence the melting temperature, while not affecting the
shearing. Finally, we discuss dislocations and thermal melting in inhomogeneous
rapidly rotating Bose-Einstein condensates; we delineate a phase diagram in the
temperature -- rotation rate plane, and infer that the thermal melting
temperature should lie below the Bose-Einstein transition temperature.


title: Migration of Star Clusters and Nuclear Rings

abstract:
  Star clusters that form in nuclear rings appear to be at slightly larger
radii than the gas. We argue that the star clusters move out from the gas in
which they are formed because of satellite-disk tidal interactions. In
calculating the dynamics of this star cluster and gas ring system, we include
the effects of dynamical friction of the background stars in the host galaxy on
the star cluster, and inflowing gas along the bar onto the nuclear ring at the
two contact points. We show that the final separation is of the order of the
Hill radius of the nuclear ring, which is typically 20-30% of its radius.
Massive star clusters can reach half of this separation very quickly and
produce a factor of a few enhancement in the gas surface density. If this leads
to star formation in addition to the (ongoing) formation of star clusters near
the contact points, a possible (initial) azimuthal age gradient may become
diluted or even disappear. Finally, if the star cluster are massive and/or
numerous enough, we expect the nuclear ring to migrate inward, away from the
(possibly) associated (inner) Lindblad resonance. We discuss how these
predictions may be tested observationally.


title: Lyapunov modes in three-dimensional Lennard-Jones fluids

abstract:
  Recent studies on the phase-space dynamics of a one-dimensional Lennard-Jones
fluid reveal the existence of regular collective perturbations associated with
the smallest positive Lyapunov exponents of the system, called hydrodynamic
Lyapunov modes, which previously could only be identified in hard-core fluids.
In this work we present a systematic study of the Lyapunov exponents and
Lyapunov vectors, i.e. perturbations along each direction of phase space, of a
three-dimensional Lennard-Jones fluid. By performing the Fourier transform of
the spatial density of the coordinate part of the Lyapunov vector components
and then time-averaging this result we find convincing signatures of
longitudinal modes, with inconclusive evidence of transverse modes for all
studied densities. Furthermore, the longitudinal modes can be more clearly
identified for the higher density values. Thus, according to our results, the
mixing of modes induced both by the dynamics and the dimensionality induce a
hitherto unknown type of order in the tangent space of the model herein studied
at high density values.


title: 'Universal' FitzGerald Contractions

abstract:
  The model of a universe with a preferred frame, which nevertheless shares the
main properties with traditional special and general relativity theories, is
considered. We adopt Mach's interpretation of inertia and show that the energy
balance equation, which includes the Machian energy of gravitational
interactions with the universe, can imitate standard relativistic formulas.


title: Construction of Error-Correcting Codes for Random Network Coding

abstract:
  In this work we present error-correcting codes for random network coding
based on rank- metric codes, Ferrers diagrams, and puncturing. For most
parameters, the constructed codes are larger than all previously known codes.


title:
On the minimal speed of traveling waves for a non-local delayed
  reaction-diffusion equation

abstract:
  In this note, we give constructive upper and lower bounds for the minimal
speed of propagation of traveling waves for non-local delayed
reaction-diffusion equation.


title:
Extended Hubbard model with renormalized Wannier wave functions in the
  correlated state: beyond the parametrized models

abstract:
  The method used earlier for analysis of correlated nanoscopic systems is
extended to infinite (periodic) s-band like systems described by the Hubbard
model and its extensions. The optimized single-particle wave functions
contained in the parameters of the Hubbard model (the hopping \textit{t} and
the magnitude of the intraatomic interaction \textit{U}) are determined
explicitly in the correlated state for the electronic systems of various
symmetries and dimensions: Hubbard chain, square and triangular planar
lattices, and the three cubic lattices (SC, BCC, FCC). In effect, the evolution
of the electronic properties as a function of interatomic distance $R$ is
obtained. The model parameters in most cases do not scale linearly with the
lattice spacing and hence, their solution as a function of microscopic
parameters reflects only qualitatively the system evolution. Also, the atomic
energy changes with $R$ and therefore should be included in the model analysis.
The solutions in one dimension (\textit{D} = 1) can be analyzed both rigorously
(by making use of the Lieb--Wu solution) and compared with the approximate
Gutzwiller treatment. In higher dimensions (\textit{D} = 2, 3) only the latter
approach is possible to implement within the scheme. The renormalized single
particle wave functions are almost independent of the choice of the scheme
selected to diagonalize the Hamiltonian in the Fock space in D=1 case. The
method can be extended to other approximation schemes as stressed at the end.


title: Energy conditions constraints on a class of f(R)-gravity

abstract:
  We present and discuss the bounds from the energy conditions on a general
f(R) functional form in the framework of metric variational approach. As a
concrete application of the energy conditions to locally homogeneous and
isotropic f(R)-cosmology, the recent estimated values of the deceleration and
jerk parameters are used to examine the bounds from the weak energy condition
on the free parameter of the family of f(R)=\sqrt{R^2 - R_0^2} gravity theory.


title: Measuring measurement

abstract:
  Measurement connects the world of quantum phenomena to the world of classical
events. It plays both a passive role, observing quantum systems, and an active
one, preparing quantum states and controlling them. Surprisingly - in the light
of the central status of measurement in quantum mechanics - there is no general
recipe for designing a detector that measures a given observable. Compounding
this, the characterization of existing detectors is typically based on partial
calibrations or elaborate models. Thus, experimental specification (i.e.
tomography) of a detector is of fundamental and practical importance. Here, we
present the realization of quantum detector tomography: we identify the optimal
positive-operator-valued measure describing the detector, with no ancillary
assumptions. This result completes the triad, state, process, and detector
tomography, required to fully specify an experiment. We characterize an
avalanche photodiode and a photon number resolving detector capable of
detecting up to eight photons. This creates a new set of tools for accurately
detecting and preparing non-classical light.


title: Disorder-induced tail states in a gapped bilayer graphene

abstract:
  The instanton approach to the in-gap fluctuation states is applied to the
spectrum of biased bilayer graphene. It is shown that the density of states
falls off with energy measured from the band-edge as $\nu(\epsilon)\propto
\exp(-|\epsilon/\epsilon_t|^{3/2})$, where the characteristic tail energy,
$\epsilon_t$, scales with the concentration of impurities, $n_i$, as
$n_i^{2/3}$. While the bare energy spectrum is characterized by two energies:
the bias-induced gap, $V$, and interlayer tunneling, $t_{\perp}$, the tail,
$\epsilon_t$, contains a {\it single} combination $V^{1/3}t_{\perp}^{2/3}$. We
show that the above expression for $\nu(\epsilon)$ in the tail actually applies
all the way down to the mid-gap.


title:
The Brera Multi-scale Wavelet Chandra Survey. I. Serendipitous source
  catalogue

abstract:
  We present the BMW-Chandra source catalogue drawn from essentially all
Chandra ACIS-I pointed observations with an exposure time in excess of 10ks
public as of March 2003 (136 observations). Using the wavelet detection
algorithm developed by Lazzati et al. (1999) and Campana et al. (1999), which
can characterise both point-like and extended sources, we identified 21325
sources. Among them, 16758 are serendipitous, i.e. not associated with the
targets of the pointings, and do not require a non-automated analysis. This
makes our catalogue the largest compilation of Chandra sources to date. The
0.5--10 keV absorption corrected fluxes of these sources range from ~3E-16 to
9E-12 erg cm^-2 s^-1 with a median of 7E-15 erg cm^-2 s^-1. The catalogue
consists of count rates and relative errors in three energy bands (total,
0.5-7keV; soft, 0.5-2keV; and hard, 2-7keV), and source positions relative to
the highest signal-to-noise detection among the three bands. The wavelet
algorithm also provides an estimate of the extension of the source. We include
information drawn from the headers of the original files, as well, and
extracted source counts in four additional energy bands, SB1 (0.5-1keV), SB2
(1-2keV), HB1 (2-4keV), and HB2 (4-7keV). We computed the sky coverage for the
full catalogue and for a subset at high Galactic latitude (|b|> 20deg). The
complete catalogue provides a sky coverage in the soft band (0.5-2keV, S/N =3)
of ~8 deg^2 at a limiting flux of 1E-13 erg cm^-2 s^-1, and ~2 deg^2 at a
limiting flux of ~1E-15 erg cm^-2 s^-1.


title:
Photo-heating and the fate of hard photons during the reionisation of
  HeII by quasars

abstract:
  We use a combination of analytic and numerical arguments to consider the
impact of quasar photo-heating during HeII reionisation on the thermal
evolution of the intergalactic medium (IGM). We demonstrate that rapid (\Delta
z< 0.1-0.2), strong (\Delta T > 10^4 K) photo-heating is difficult to achieve
across the entire IGM unless quasar spectra are significantly harder than
implied by current observational constraints. Although filtering of intrinsic
quasar radiation through dense regions in the IGM does increase the mean excess
energy per HeII photo-ionisation, it also weakens the radiation intensity and
lowers the photo-ionisation rate, preventing rapid heating over time intervals
shorter than the local photo-ionisation timescale. Moreover, the hard photons
responsible for the strongest heating are more likely to deposit their energy
inside dense clumps. The abundance of such clumps is, however, uncertain and
model-dependent, leading to a fairly large uncertainty in the photo-heating
rates. Nevertheless, although some of the IGM may be exposed to a hardened and
weakened ionising background for long periods, most of the IGM must instead be
reionised by the more abundant, softer photons and with accordingly modest
heating rates (\Delta T < 10^4 K). The repeated ionisation of fossil quasar
HeIII regions does not increase the net heating because the recombination times
in these regions typically exceed the IGM cooling times and the average time
lag between successive rounds of quasar activity. Detailed line-of-sight
radiative transfer simulations confirm these expectations and predict a rich
thermal structure in the IGM during HeII reionisation. [Abridged]


title:
Clustering of Luminous Red Galaxies III: Detection of the Baryon
  Acoustic Peak in the 3-point Correlation Function

abstract:
  We present the 3-point function \xi_3 and Q_3=\xi_3/\xi_2^2 for a
spectroscopic sample of luminous red galaxies (LRG) from SDSS DR6 & DR7. We
find a strong (S/N$>$6) detection of $Q_3$ on scales of 55-125 Mpc/h, with a
well defined peak around 105 Mpc/h in all \xi_2, \xi_3 and Q_3, in excellent
agreement with the predicted shape and location of the imprint of the baryon
acoustic oscillations (BAO). We use very large simulations to asses and test
the significance of our measurement. Models without the BAO peak are ruled out
by the $Q_3$ data with 99% confidence. Our measurements show the expected shape
for Q_3 as a function of the triangular configuration. This provides a first
direct measurement of the non-linear mode coupling coefficients of density and
velocity fluctuations which, on these large scales, are independent of cosmic
time, the amplitude of fluctuations or cosmological parameters. The location of
the BAO peak in the data indicates \Omega_m =0.28 \pm 0.05 and \Omega_B=0.079
\pm 0.025 (h=0.70) after marginalization over spectral index (n_s=0.8-1.2)
linear b_1 and quadratic c_2 bias,which are found to be in the range:
b_1=1.7-2.2 and c_2=0.75-3.55. The data allows a hierarchical contribution from
primordial non-Gaussianities in the range Q_3=0.55-3.35. These constraints are
independent and complementary to the ones that can be obtained using the
2-point function, which are presented in a separate paper. This is the first
detection of the shape of $Q_3$ on BAO scales, but our errors are shot-noise
dominated and the SDSS volume is still relatively small, so there is ample room
for future improvement in this type of measurements.


title: Non-linear evolution of f(R) cosmologies I: methodology

abstract:
  We introduce the method and the implementation of a cosmological simulation
of a class of metric-variation f(R) models that accelerate the cosmological
expansion without a cosmological constant and evade solar-system bounds of
small-field deviations to general relativity. Such simulations are shown to
reduce to solving a non-linear Poisson equation for the scalar degree of
freedom introduced by the f(R) modifications. We detail the method to
efficiently solve the non-linear Poisson equation by using a
Newton-Gauss-Seidel relaxation scheme coupled with multigrid method to
accelerate the convergence. The simulations are shown to satisfy tests
comparing the simulated outcome to analytical solutions for simple situations,
and the dynamics of the simulations are tested with orbital and Zeldovich
collapse tests. Finally, we present several static and dynamical simulations
using realistic cosmological parameters to highlight the differences between
standard physics and f(R) physics. In general, we find that the f(R)
modifications result in stronger gravitational attraction that enhances the
dark matter power spectrum by ~20% for large but observationally allowed f(R)
modifications. More detailed study of the non-linear f(R) effects on the power
spectrum are presented in a companion paper.


title: Dynamical Mass of the Substellar Benchmark Binary HD 130948BC

abstract:
  (Abridged) We present Keck, HST, and Gemini-North observations of the L4+L4
binary HD 130948BC which together span ~70% of the binary's orbital period. We
determine a total dynamical mass of 0.109+/-0.002 Msun (114+/-2 Mjup). The flux
ratio is near unity, so both components are unambiguously substellar for any
plausible mass ratio. An independent constraint on the age of the system is
available from the G2V primary HD 130948A. The available indicators suggest an
age comparable to the Hyades, with the most precise age being 0.79 Gyr based on
gyrochronology. Therefore, HD 130948BC is now a unique benchmark among field L
and T dwarfs, with a well-determined mass, luminosity, and age. We find that
substellar theoretical models disagree with our observations. Both components
of HD 130948BC appear to be overluminous by a factor of ~2-3x compared to
evolutionary models. The age of the system would have to be notably younger
than the gyro age to ameliorate the luminosity disagreement. However,
regardless of the adopted age, evolutionary and atmospheric models give
inconsistent results, indicating systematic errors in at least one class of
models, possibly both. The masses of HD 130948BC happen to be very near the
theoretical mass limit for lithium burning, and thus measuring the differential
lithium depletion between B and C will provide a uniquely discriminating test
of theoretical models. The potential underestimate of luminosities by
evolutionary models would have wide-ranging implications; therefore, a more
refined age estimate for HD 130948A is critically needed.


title: Correlated X-ray/Optical Variability in the Quasar MR2251-178

abstract:
  Emission from Active Galactic Nuclei is known to vary strongly over time over
a wide energy band, but the origin of the variability and especially of the
inter-band correlations is still not well established. Here we present the
results of our X-ray and optical monitoring campaign of the quasar MR2251-178,
covering a period of 2.5 years. The X-ray 2-10 keV flux is remarkably well
correlated with the optical B, V and R bands, their fluctuations are almost
simultaneous with a delay consistent with 0 days and not larger than 4 days in
either direction. The amplitude of variations shows an intriguing behaviour:
rapid, large amplitude fluctuations over tens of days in the X-rays have only
small counterparts in the optical bands, while the long-term trends over
hundreds of days are stronger in the B band than in X-rays. We show that simple
reprocessing models, where all the optical variability arises from the variable
X-ray heating, cannot simultaneously explain the discrepant variability
amplitudes on different time-scales and the short delays between X-ray and
optical bands. We interpret the variability and correlations, in the
optically-thick accretion disc plus corona scenario, as the result of intrinsic
accretion rate variations modulating both X-ray and optical emission, together
with reprocessing of X-rays by the accretion disc.


title:
The Luminosity and Mass Functions of Low-Mass Stars in the Galactic
  Disk: I. The Calibration Region

abstract:
  We present measurements of the luminosity and mass functions of low-mass
stars constructed from a catalog of matched Sloan Digital Sky Survey (SDSS) and
2 Micron All Sky Survey (2MASS) detections. This photometric catalog contains
more than 25,000 matched SDSS and 2MASS point sources spanning ~30 square
degrees on the sky. We have obtained follow-up spectroscopy, complete to J=16,
of more than 500 low mass dwarf candidates within a 1 square degree sub-sample,
and thousands of additional dwarf candidates in the remaining 29 square
degrees. This spectroscopic sample verifies that the photometric sample is
complete, uncontaminated, and unbiased at the 99% level globally, and at the
95% level in each color range. We use this sample to derive the luminosity and
mass functions of low-mass stars over nearly a decade in mass (0.7 M_sun > M_*
> 0.1 M_sun). We find that the logarithmically binned mass function is best fit
with an M_c=0.29 log-normal distribution, with a 90% confidence interval of
M_c=0.20--0.50. These 90% confidence intervals correspond to linearly binned
mass functions peaking between 0.27 M_sun and 0.12 M_sun, where the best fit MF
turns over at 0.17 M_sun. A power law fit to the entire mass range sampled
here, however, returns a best fit of alpha=1.1 (where the Salpeter slope is
alpha = 2.35). These results agree well with most previous investigations,
though differences in the analytic formalisms adopted to describe those mass
functions can give the false impression of disagreement. Given the richness of
modern-day astronomical datasets, we are entering the regime whereby stronger
conclusions can be drawn by comparing the actual datapoints measured in
different mass functions, rather than the results of analytic analyses that
impose structure on the data a priori. (abridged)


title:
Epicyclic Motions and Standing Shocks in Numerically Simulated Tilted
  Black-Hole Accretion Disks

abstract:
  This work presents a detailed analysis of the overall flow structure and
unique features of the inner region of the tilted disk simulations described in
Fragile et al. (2007). The primary new feature identified in the main disk body
is a latitude-dependent radial epicyclic motion driven by pressure gradients
attributable to the gravitomagnetic warping of the disk. The induced motion of
the gas is coherent over the scale of the entire disk and is fast enough that
it could be observable in features such as relativistic iron lines. The
eccentricity of the associated fluid element trajectories increases with
decreasing radius, leading to a crowding of orbit trajectories near their
apocenters. This results in a local density enhancement akin to a compression.
These compressions are sufficiently strong to produce a pair of weak shocks in
the vicinity of the black hole. These shocks are roughly aligned with the
line-of-nodes between the black-hole symmetry plane and disk midplane, with one
shock above the line-of-nodes on one side of the black hole and the other below
on the opposite side. These shocks enhance angular momentum transport and
energy dissipation near the hole, forcing some material to plunge toward the
black hole from well outside the innermost stable circular orbit. A new,
extended simulation, which was evolved for more than a full disk precession
period, allows us to confirm that these shocks and the previously identified
``plunging streams'' precess with the disk in such a way as to remain aligned
relative to the line-of-nodes, as expected based on our physical understanding
of these phenomena. Such a precessing structure would likely present a strong
quasi-periodic signal.


title:
Constructive pointfree topology eliminates non-constructive
  representation theorems from Riesz space theory

abstract:
  In Riesz space theory it is good practice to avoid representation theorems
which depend on the axiom of choice. Here we present a general methodology to
do this using pointfree topology. To illustrate the technique we show that
almost f-algebras are commutative. The proof is obtained relatively
straightforward from the proof by Buskes and van Rooij by using the pointfree
Stone-Yosida representation theorem by Coquand and Spitters.


title:
Secant varieties to osculating varieties of Veronese embeddings of
  $\mathbb{P}^n$

abstract:
  A well known theorem by Alexander-Hirschowitz states that all the higher
secant varieties of $V_{n,d}$ (the $d$-uple embedding of $\mathbb{P}^n$) have
the expected dimension, with few known exceptions. We study here the same
problem for $T_{n,d}$, the tangential variety to $V_{n,d}$, and prove a
conjecture, which is the analogous of Alexander-Hirschowitz theorem, for $n\leq
9$. Moreover. we prove that it holds for any $n,d$ if it holds for $d=3$. Then
we generalize to the case of $O_{k,n,d}$, the $k$-osculating variety to
$V_{n,d}$, proving, for $n=2$, a conjecture that relates the defectivity of
$\sigma_s(O_{k,n,d})$ to the Hilbert function of certain sets of fat points in
$\mathbb{P}^n$.


title: A Coincidence Problem: How to Flow from N=2 SQCD to N=1 SQCD

abstract:
  We discuss, and propose a solution for, a still unresolved problem regarding
the breaking from $\N=2$ super-QCD to $\N=1$ super-QCD. A mass term $W=\mu \Tr
\Phi^2 / 2$ for the adjoint field, which classically does the required breaking
perfectly, quantum mechanically leads to a relevant operator that, in the
infrared, makes the theory flow away from pure $\N=1$ SQCD. To avoid this
problem, we first need to extend the theory from $\SU (n_c)$ to $\U (n_c)$. We
then look for the quantum generalization of the condition $W^{\prime}(m)=0$,
that is, the coincidence between a root of the derivative of the superpotential
$W(\phi)$ and the mass $m$ of the quarks. There are $2n_c -n_f$ of such points
in the moduli space. We suggest that with an opportune choice of
superpotential, that selects one of these coincidence vacua in the moduli
space, it is possible to flow from $\N=2$ SQCD to $\N=1$ SQCD. Various
arguments support this claim. In particular, we shall determine the exact
location in the moduli space of these coincidence vacua and the precise
factorization of the SW curve.


title: Nuclear physics aspects of double beta decay

abstract:
  Comprehensive description of the phenomenology of the $\beta\beta$ decay is
given, with emphasis on the nuclear physics aspects. After a brief review of
the neutrino oscillation results and of motivation to test the lepton number
conservation, the mechanism of the $0\nu\beta\beta$ is discussed. Its relation
to the lepton flavor violation involving charged leptons and its use as a
diagnostic tool of the $0\nu\beta\beta$ mechanism is described. Next the basic
nuclear physics of both $\beta\beta$-decay modes is presented, and the decay
rate formulae derived. The nuclear physics methods used, the nuclear shell
model and the quasiparticle random phase approximation, are described next, and
the choice of input parameters is discussed in the following section. Finally,
the numerical values of the nuclear matrix elements, and their uncertainty, are
presented. In the appendix the relation of the search for the neutrino magnetic
moment to the Dirac versus Majorana nature of neutrinos is described.


title: Theory of the superglass phase

abstract:
  A superglass is a phase of matter which is characterized at the same time by
superfluidity and a frozen amorphous structure. We introduce a model of
interacting bosons in three dimensions that displays this phase unambiguously
and that can be analyzed exactly or using controlled approximations. Employing
a mapping between quantum Hamiltonians and classical Fokker-Planck operators,
we show that the ground state wavefunction of the quantum model is proportional
to the Boltzmann measure of classical hard spheres. This connection allows us
to obtain quantitative results on static and dynamic quantum correlation
functions. In particular, by translating known results on the glassy dynamics
of Brownian hard spheres we work out the properties of the superglass phase and
of the quantum phase transition between the superfluid and the superglass
phase.


title:
QCD radiative correction to pair-annihilation of spin-1 bosonic Dark
  Matter

abstract:
  The next-to-leading order (NLO) QCD corrections are calculated for the
pair-annihilation of spin-1 dark matter (DM) by dimensionally regularizing both
ultraviolet and infrared singularities in non-relativistic limit (v<<1). The
complete O(alphas) correction is about 8% due to the massless gluon
contribution. An extra 5% will be added if there is a new interaction from a
massive gluon of approximately same mass as the DM particle. The NLO QCD
correction could give the sizable shift to the DM mass constrained by relic
density measurements.


title:
Clustering of luminous red galaxies I: large scale redshift space
  distortions

abstract:
  This is the first paper of a series where we study the clustering of LRG
galaxies in the latest spectroscopic SDSS data release, DR6, which has 75000
LRG galaxies covering over 1 $Gpc^3/h^3$ at $0.15<z<0.47$. Here we focus on
modeling redshift space distortions in $\xips$, the 2-point correlation in
separate line-of-sight and perpendicular directions, on large scales. % and
away from the line-of-sight. We use large mock simulations to study the
validity of models and errors. We show that errors in the data are dominated by
a shot-noise term that is 40% larger than the Poisson error commonly used. We
first use the normalized quadrupole for the whole sample (mean z=0.34) to
estimate $\beta=f(\Omega_m)/b=0.34 \pm 0.03$, where $f(\Omega_m)$ is the linear
velocity growth factor and $b$ is the linear bias parameter that relates galaxy
to matter fluctuations on large scales. We next use the full $\xips$ plane to
find $\Omega_{0m}= 0.245 \pm 0.020$ (h=0.72) and the biased amplitude $b
\sigma_8 = 1.56 \pm 0.09$. For standard gravity, we can combine these
measurements to break degeneracies and find $\sigma_8=0.85 \pm 0.06$, $b=1.85
\pm 0.25$ and $f(\Omega_m)=0.64 \pm 0.09$. We present constraints for modified
theories of gravity and find that standard gravity is consistent with data as
long as $0.80<\sigma_8<0.92$. We also calculate the cross-correlation with
WMAP5 and show how both methods to measure the growth history are complementary
to constrain non-standard models of gravity. Finally, we show results for
different redshift slices, including a prominent BAO peak in the monopole at
different redshifts. (Abridged)


title:
Clustering of luminous red galaxies II: small scale redshift space
  distortions

abstract:
  This is the second paper of a series where we study the clustering of LRG
galaxies in the latest spectroscopic SDSS data release, DR6, which has 75000
LRG galaxies covering over 1 $Gpc^3/h^3$ for $0.15<z<0.47$. Here we focus on
modeling redshift space distortions in $\xisp$, the 2-point correlation in
separate line-of-sight and perpendicular directions, at small scales and in the
line-of-sight. We show that a simple Kaiser model for the anisotropic 2-point
correlation function in redshift space, convolved with a distribution of random
peculiar velocities with an exponential form, can describe well the correlation
of LRG at all scales. We show that to describe with accuracy the so called
"fingers-of-God" (FOG) elongations in the radial direction, it is necessary to
model the scale dependence of both bias $b$ and the pairwise rms peculiar
velocity $\sigma_{12}$ with the distance. We show how both quantities can be
inferred from the $\xisp$ data. From $r \simeq 10$ Mpc/h to $r \simeq 1$ Mpc/h,
both the bias and $\sigma_{12}$ are shown to increase by a factor of two: from
$b=2$ to $b=4$ and from $\sigma_{12}=400$ to 800 Km/s. The later is in good
agreement, within a 5 percent accuracy in the recovered velocities, with direct
velocity measurements in dark matter simulations with $\Omega_m=0.25$ and
$\sigma_8$=0.85.


title: Non-linear evolution of f(R) cosmologies II: power spectrum

abstract:
  We carry out a suite of cosmological simulations of modified action f(R)
models where cosmic acceleration arises from an alteration of gravity instead
of dark energy. These models introduce an extra scalar degree of freedom which
enhances the force of gravity below the inverse mass or Compton scale of the
scalar. The simulations exhibit the so-called chameleon mechanism, necessary
for satisfying local constraints on gravity, where this scale depends on
environment, in particular the depth of the local gravitational potential. We
find that the chameleon mechanism can substantially suppress the enhancement of
power spectrum in the non-linear regime if the background field value is
comparable to or smaller than the depth of the gravitational potentials of
typical structures. Nonetheless power spectrum enhancements at intermediate
scales remain at a measurable level for models even when the expansion history
is indistinguishable from a cosmological constant, cold dark matter model.
Simple scaling relations that take the linear power spectrum into a non-linear
spectrum fail to capture the modifications of f(R) due to the change in
collapsed structures, the chameleon mechanism, and the time evolution of the
modifications.


title: Automata and cells in affine Weyl groups

abstract:
  Let W~ be an affine Weyl group, and let C be a left, right, or two-sided
Kazhdan--Lusztig cell in W~. Let Reduced (C) be the set of all reduced
expressions of elements of C, regarded as a formal language in the sense of the
theory of computation. We show that Reduced (C) is a regular language. Hence
the reduced expressions of the elements in any Kazhdan--Lusztig cell can be
enumerated by a finite state automaton.


title: On "Bit-Interleaved Coded Multiple Beamforming"

abstract:
  The interleaver design criteria described in [1] should take into account all
error patterns of interest.


title: Describing viable technicolor scenarios

abstract:
  We construct an effective lagrangian for new strong interactions at the LHC,
including as a first step the two lightest triplets of spin-1 resonances. Our
parametrization is general enough to allow for previously unstudied spectrum
and couplings. Among available frameworks to describe the spin-1 sector, we
rely on an extra-dimensional description. Our approach limits the number of
parameters, yet is versatile enough to describe the phenomenology of a wide
range of new scenarios of strong electroweak symmetry breaking.


title:
A Grateful Dead Analysis: The Relationship Between Concert and Listening
  Behavior

abstract:
  The Grateful Dead were an American band that was born out of the San
Francisco, California psychedelic movement of the 1960s. The band played music
together from 1965 to 1995 and is well known for concert performances
containing extended improvisations and long and unique set lists. This article
presents a comparative analysis between 1,590 of the Grateful Dead's concert
set lists from 1972 to 1995 and 2,616,990 last.fm Grateful Dead listening
events from August 2005 to October 2007. While there is a strong correlation
between how songs were played in concert and how they are listened to by
last.fm members, the outlying songs in this trend identify interesting aspects
of the band and their fans 10 years after the band's dissolution.


title:
Wavefront error correction and Earth-like planet detection by
  Self-Coherent Camera in space

abstract:
  In the context of exoplanet detection, the performance of coronagraphs is
limited by wavefront errors. To efficiently correct for these aberrations with
a deformable mirror, it is mandatory to measure them using the science detector
with a very high accuracy. The Self-Coherent Camera which is based on light
incoherence between star and its environment enables an estimation of these
wavefront errors. That estimation is directly derived from the encoded speckles
in the science image. This avoids differential errors due to beam separation
and non common optics. Earth-like planet detection is demonstrated by numerical
simulations under realistic assumptions for a space telescope. The
Self-Coherent Camera is an attractive technique for future space telescopes. It
is also one of the techniques under investigation for the E-ELT planet finder
so-called EPICS.


title:
Quantum bistability and spin current shot noise of a single quantum dot
  coupled to an optical microcavity

abstract:
  Here we explore spin dependent quantum transport through a single quantum dot
coupled to an optical microcavity. The spin current is generated by electron
tunneling between a single doped reservoir and the dot combined with intradot
spin flip transitions induced by a quantized cavity mode. In the limit of
strong Coulomb blockade, this model is analogous to the Jaynes-Cummings model
in quantum optics and generates a pure spin current in the absence of any
charge current. Earlier research has shown that in the classical limit where a
large number of such dots interact with the cavity field, the spin current
exhibits bistability as a function of the laser amplitude that drives the
cavity. We show that in the limit of a single quantum dot this bistability
continues to be present in the intracavity photon statistics. Signatures of the
bistable photon statistics manifest themselves in the frequency dependent shot
noise of the spin current despite the fact that the quantum mechanical average
spin current no longer exhibits bistability. Besides having significance for
future quantum dot based optoelectronic devices, our results shed light on the
relation between bistability, which is traditionally viewed as a classical
effect, and quantum mechanics.


title: The Arcminute Microkelvin Imager

abstract:
  The Arcminute Microkelvin Imager is a pair of interferometer arrays operating
with six frequency channels spanning 13.9-18.2 GHz, with very high sensitivity
to angular scales 30''-10'. The telescope is aimed principally at
Sunyaev-Zel'dovich imaging of clusters of galaxies. We discuss the design of
the telescope and describe and explain its electronic and mechanical systems.


title: Charmonium and bottomonium production in heavy-ion collisions

abstract:
  We review the present status in the theoretical and phenomenological
understanding of charmonium and bottomonium production in heavy-ion collisions.
We start by recapitulating the basic notion of "anomalous quarkonium
suppression" in heavy-ion collisions and its recent amendments involving
regeneration reactions. We then survey in some detail concepts and ingredients
needed for a comprehensive approach to utilize heavy quarkonia as a probe of
hot and dense matter. The theoretical discussion encompasses recent lattice QCD
computations of quarkonium properties in the Quark-Gluon Plasma, their
interpretations using effective potential models, inelastic rate calculations
and insights from analyses of electromagnetic plasmas. We illustrate the
powerful techniques of thermodynamic Green functions (T-matrices) to provide a
general framework for implementing microscopic properties of heavy quarkonia
into a kinetic theory of suppression and regeneration reactions. The
theoretical concepts are tested in applications to heavy-ion reactions at SPS,
RHIC and LHC. We outline perspectives for future experiments on charmonium and
bottomonium production in heavy-ion collisions over a large range in energy
(FAIR, RHIC-II and LHC). These are expected to provide key insights into
hadronic matter under extreme conditions using quarkonium observables.


title: An ESPRIT-based approach for Initial Ranging in OFDMA systems

abstract:
  This work presents a novel Initial Ranging scheme for orthogonal
frequency-division multiple-access networks. Users that intend to establish a
communication link with the base station (BS) are normally misaligned both in
time and frequency and the goal is to jointly estimate their timing errors and
carrier frequency offsets with respect to the BS local references. This is
accomplished with affordable complexity by resorting to the ESPRIT algorithm.
Computer simulations are used to assess the effectiveness of the proposed
solution and to make comparisons with existing alternatives.


title: Inapproximability for metric embeddings into R^d

abstract:
  We consider the problem of computing the smallest possible distortion for
embedding of a given n-point metric space into R^d, where d is fixed (and
small). For d=1, it was known that approximating the minimum distortion with a
factor better than roughly n^(1/12) is NP-hard. From this result we derive
inapproximability with factor roughly n^(1/(22d-10)) for every fixed d\ge 2, by
a conceptually very simple reduction. However, the proof of correctness
involves a nontrivial result in geometric topology (whose current proof is
based on ideas due to Jussi Vaisala).
  For d\ge 3, we obtain a stronger inapproximability result by a different
reduction: assuming P \ne NP, no polynomial-time algorithm can distinguish
between spaces embeddable in R^d with constant distortion from spaces requiring
distortion at least n^(c/d), for a constant c>0. The exponent c/d has the
correct order of magnitude, since every n-point metric space can be embedded in
R^d with distortion O(n^{2/d}\log^{3/2}n) and such an embedding can be
constructed in polynomial time by random projection.
  For d=2, we give an example of a metric space that requires a large
distortion for embedding in R^2, while all not too large subspaces of it embed
almost isometrically.


title: Differential operators, shifted parts, and hook lengths

abstract:
  We discuss Sekiguchi-type differential operators, their eigenvalues, and a
generalization of Andrews-Goulden-Jackson formula. These will be applied to
extract explicit formulae involving shifted partitions and hook lengths.


title: Strong diamagnetic response of metamaterials

abstract:
  We demonstrate that there is a strong diamagnetic response of metamaterials,
consisting of open or closed split ring resonators (SRRs). Detailed numerical
work shows that for densely packed SRRs the magnetic permeability,
$\mu(\omega)$, does not approach unity, as expected for frequencies lower and
higher than the resonance frequency, $\omega_0$. Below $\omega_0$,
$\mu(\omega)$ gives values ranging from 0.9 to 0.6 depending of the width of
the metallic ring, while above $\omega_0$, $\mu(\omega)$ is close to 0.5.
Closed rings have $\mu\approx 0.5$ over a wide frequency range independently of
the width of the ring. A simple model that uses the inner and outer current
loop of the SRRs can easily explain theoretically this strong diamagnetic
response, which can be used in magnetic levitation.


title: Opportunistic Collaborative Beamforming with One-Bit Feedback

abstract:
  An energy-efficient opportunistic collaborative beamformer with one-bit
feedback is proposed for ad hoc sensor networks over Rayleigh fading channels.
In contrast to conventional collaborative beamforming schemes in which each
source node uses channel state information to correct its local carrier offset
and channel phase, the proposed beamforming scheme opportunistically selects a
subset of source nodes whose received signals combine in a quasi-coherent
manner at the intended receiver. No local phase-precompensation is performed by
the nodes in the opportunistic collaborative beamformer. As a result, each node
requires only one-bit of feedback from the destination in order to determine if
it should or shouldn't participate in the collaborative beamformer. Theoretical
analysis shows that the received signal power obtained with the proposed
beamforming scheme scales linearly with the number of available source nodes.
Since the the optimal node selection rule requires an exhaustive search over
all possible subsets of source nodes, two low-complexity selection algorithms
are developed. Simulation results confirm the effectiveness of opportunistic
collaborative beamforming with the low-complexity selection algorithms.


title:
Two extremely luminous WN stars in the Galactic center with
  circumstellar emission from dust and gas

abstract:
  We study relatively isolated massive WN-type stars in the Galactic center.
The K-band spectra of WR102ka and WR102c are exploited to infer the stellar
parameters and to compute synthetic stellar spectra using the Potsdam
Wolf-Rayet (PoWR) model atmosphere code. These models are combined with
dust-shell models for analyzing the Spitzer IRS spectra of these objects.
Archival IR images complement the interpretation. We report that WR102ka and
WR102c are among the most luminous stars in the Milky Way. The mid-IR continua
for both objects are dominated by dust emission. For the first time we report
the presence of dust in the close vicinity of WN stars. Also for the first
time, we have detected lines of pure-rotational transitions of molecular
hydrogen in a massive-star nebula. A peony-shaped nebula around 102ka is
resolved by the Spitzer MIPS camera. We attribute the formation of this nebula
to the recent evolutionary history of WR102ka.


title: Noether-Lefschetz theory and the Yau-Zaslow conjecture

abstract:
  The Yau-Zaslow conjecture determines the reduced genus 0 Gromov-Witten
invariants of K3 surfaces in terms of the Dedekind eta function. Classical
intersections of curves in the moduli of K3 surfaces with Noether-Lefschetz
divisors are related to 3-fold Gromov-Witten theory via the K3 invariants.
Results by Borcherds and Kudla-Millson determine the classical intersections in
terms of vector-valued modular forms. Proven mirror transformations can often
be used to calculate the 3-fold invariants which arise.
  Via a detailed study of the STU model (determining special curves in the
moduli of K3 surfaces), we prove the Yau-Zaslow conjecture for all curve
classes on K3 surfaces. Two modular form identities are required. The first,
the Klemm-Lerche-Mayr identity relating hypergeometric series to modular forms
after mirror transformation, is proven here. The second, the Harvey-Moore
identity, is proven by D. Zagier and presented in the paper.


title:
Low Loss Metamaterials Based on Classical Electromagnetically Induced
  Transparency

abstract:
  We demonstrate theoretically that electromagnetically induced transparency
can be achieved in metamaterials, in which electromagnetic radiation is
interacting resonantly with mesoscopic oscillators rather than with atoms. We
describe novel metamaterial designs that can support full dark resonant state
upon interaction with an electromagnetic beam and we present results of its
frequency-dependent effective permeability and permittivity. These results,
showing a transparency window with extremely low absorption and strong
dispersion, are confirmed by accurate simulations of the electromagnetic field
propagation in the metamaterial.


title: Wide-angle perfect absorber/thermal emitter in the THz regime

abstract:
  We show that a perfect absorber/thermal emitter exhibiting an absorption peak
of 99.9% can be achieved in metallic nanostructures that can be easily
fabricated. The very high absorption is maintained for large angles with a
minimal shift in the center frequency and can be tuned throughout the visible
and near-infrared regime by scaling the nanostructure dimensions. The stability
of the spectral features at high temperatures is tested by simulations using a
range of material parameters.


title:
Transversity and T-odd PDFs from Drell-Yan processes with $pp$, $pD$ and
  $DD$ collisions

abstract:
  We estimate the single-spin asymmetries (SSA) which provide the access to
transversity as well as to Boer-Mulders and Sivers PDFs via investigation of
the single-polarized Drell-Yan (DY) processes with $ pp$, $pD$ and $DD$
collisions available to RHIC, NICA, COMPASS, and J-PARC. The feasibility of
these SSA is studied with the new generator of polarized DY events. The
performed estimations demonstrate that there exist the such kinematical regions
where SSA are presumably measurable. The most useful for PDFs extraction are
the limiting kinematical ranges, where one can neglect the sea PDFs
contributions which occur at large values of Bjorken x. It is of interest that
on the contrary to the Sivers PDF, the transversity PDF is presumably
accessible only in the especial kinematical region. On the contrary to the
option with the symmetric collider mode (RHIC, NICA), this is of importance for
the COMPASS experiment and the future J-PARC facility where the fixed target
mode is available.


title:
Small Solutions to the Large Telescope Problem: A Massively Replicated
  MEMS Spectrograph

abstract:
  In traditional seeing-limited observations the spectrograph aperture scales
with telescope aperture, driving sizes and costs to enormous proportions. We
propose a new solution to the seeing-limited spectrograph problem. A massively
fiber-sliced configuration feeds a set of small diffraction-limited
spectrographs. We present a prototype, tunable, J-band, diffraction grating,
designed specifically for Astronomical applications: The grating sits at the
heart of a spectrograph, no bigger than a few inches on a side. Throughput
requirements dictate using tens-of-thousands of spectrographs on a single 10 to
30 meter telescope. A full system would cost significantly less than typical
instruments on 10m or 30m telescopes.


title:
Strong A-infinity weights, Besov and Sobolev capacities in metric
  measure spaces

abstract:
  This article studies strong A-infinity weights in Ahlfors Q-regular and
geodesic metric spaces satisfying a weak (1,s)-Poincare inequality for some
1<s<=Q, where Q is finite. It is shown that whenever max(1,Q-1)<s<=Q, a
function u yields a strong A-infinity weight of the form w=exp(Qu) if u has a
minimal s-weak upper gradient with sufficiently small Morrey norm. Similarly,
it is proved that if 1<Q<p for some finite p, then w=exp(Qu) is a strong
A-infinity weight whenever u has sufficiently small Besov p-seminorm.


title:
Redshifted Absorption at He I 10830 as a Probe of the Accretion Geometry
  of T Tauri Stars

abstract:
  We probe the geometry of magnetospheric accretion in classical T Tauri stars
by modeling red absorption at He I 10830 via scattering of the stellar and
veiling continua. Under the assumptions that the accretion flow is an
azimuthally symmetric dipole and helium is sufficiently optically thick that
all incident 1-micron radiation is scattered, we illustrate the sensitivity of
He I 10830 red absorption to both the size of the magnetosphere and the filling
factor of the hot accretion shock. We compare model profiles to those observed
in 21 CTTS with subcontinuum redshifted absorption at He I 10830 and find that
about half of the stars have red absorptions and 1-micron veilings that are
consistent with dipole flows of moderate width with accretion shock filling
factors matching the size of the magnetospheric footpoints. However, the
remaining 50% of the profiles, with a combination of broad, deep absorption and
low 1-micron veiling, require very wide flows where magnetic footpoints are
distributed over 10-20% of the stellar surface but accretion shock filling
factors are < 1%. We model these profiles by invoking large magnetospheres
dilutely filled with accreting gas, leaving the disk over a range of radii in
many narrow "streamlets" that fill only a small fraction of the entire infall
region. In some cases accreting streamlets need to originate in the disk
between several stellar radii and at least the corotation radius. A few stars
have such deep absorption at velocities greater than half the stellar escape
velocity that flows near the star with less curvature than a dipole trajectory
seem to be required.


title: Light-Front Holography and Hadronization at the Amplitude Level

abstract:
  The correspondence between theories in anti-de Sitter space and conformal
field theories in physical space-time leads to an analytic, semiclassical model
for strongly-coupled QCD which has scale invariance at short distances and
color confinement at large distances. Light-front holography is a remarkable
feature of AdS/CFT: it allows hadronic amplitudes in the AdS fifth dimension to
be mapped to frame-independent light-front wavefunctions of hadrons in physical
space-time, thus providing a relativistic description of hadrons at the
amplitude level. Some novel features of QCD are discussed, including the
consequences of confinement for quark and gluon condensates and the behavior of
the QCD coupling in the infrared. We suggest that the spatial support of QCD
condensates is restricted to the interior of hadrons, since they arise due to
the interactions of confined quarks and gluons. Chiral symmetry is thus broken
in a limited domain of size of the inverse pion mass in analogy to the limited
physical extent of superconductor phases. A new method for computing the
hadronization of quark and gluon jets at the amplitude level, an event
amplitude generator, is outlined.


title:
Upper and lower limits on the Crab pulsar's astrophysical parameters set
  from gravitational wave observations by LIGO: braking index and energy
  considerations

abstract:
  The Laser Interferometer Gravitational Observatory (LIGO) has recently
reached the end of its fifth science run (S5), having collected more than a
year worth of data. Analysis of the data is still ongoing but a positive
detection of gravitational waves, while possible, is not realistically expected
for most likely sources. This is particularly true for what concerns
gravitational waves from known pulsars. In fact, even under the most optimistic
(and not very realistic) assumption that all the pulsar's observed spin-down is
due to gravitational waves, the gravitational wave strain at earth from all the
known isolated pulsars (with the only notable exception of the Crab pulsar)
would not be strong enough to be detectable by existing detectors. By August
2006, LIGO had produced enough data for a coherent integration capable to
extract signal from noise that was weaker than the one expected from the Crab
pulsar's spin-down limit. No signal was detected, but beating the spin-down
limit is a considerable achievement for the LIGO Scientific Collaboration
(LSC). It is customary to translate the upper limit on strain from a pulsar
into a more astrophysically significant upper limit on ellipticity. Once the
spin-down limit has been beaten, it is possible to release the constraint that
all the spin-down is due to gravitational wave emission. A more complete model
with diverse braking mechanisms can be used to set limits on several
astrophysical parameters of the pulsar. This paper shows possible values of
such parameters for the Crab pulsar given the current limit on gravitational
waves from this neutron star.


title: Brownian survival and Lifshitz tail in perturbed lattice disorder

abstract:
  We consider the annealed asymptotics for the survival probability of Brownian
motion among randomly distributed traps. The configuration of the traps is
given by independent displacements of the lattice points. We determine the long
time asymptotics of the logarithm of the survival probability up to a
multiplicative constant. As applications, we show the Lifshitz tail effect of
the density of states of the associated random Schr\"{o}dinger operator and
derive a quantitative estimate for the strength of intermittency in the
Parabolic Anderson problem.


title: The relative hyperbolicity of one-relator relative presentations

abstract:
  We prove that if $G$ is a free-torsion group and $w(t)$ is a word in the
alphabet $G \sqcup \{t^{\pm 1}\}$ with exponent sum one, then the group
$<G,t|(w(t))^k = 1>$, where $k \geq 2$, is relatively hyperbolic with respect
to $G$.


title: Symplectic Floer homology of area-preserving surface diffeomorphisms

abstract:
  The symplectic Floer homology HF_*(f) of a symplectomorphism f:S->S encodes
data about the fixed points of f using counts of holomorphic cylinders in R x
M_f, where M_f is the mapping torus of f. We give an algorithm to compute
HF_*(f) for f a surface symplectomorphism in a pseudo-Anosov or reducible
mapping class, completing the computation of Seidel's HF_*(h) for h any
orientation-preserving mapping class.


title: Non-uniqueness of phase shift in central scattering due to monodromy

abstract:
  Scattering at a central potential is completely characterized by the phase
shifts which are the differences in phase between outgoing scattered and
unscattered partial waves. In this letter it is shown that, for 2D scattering
at a repulsive central potential, the phase shift cannot be uniquely defined
due to a topological obstruction which is similar to monodromy in bound
systems.


title:
Generation of field mediated three qubit entangled state shared by Alice
  and Bob

abstract:
  A scheme to generate shared tripartite entangled states, with two-trapped
atoms in a cavity held by Alice (qubits A1 and A2) entangled to a single
trapped atom in a remote lab owned by Bob (B), is proposed. The entanglement is
generated through interaction of trapped atoms with two mode squeezed light
shared by the two cavities. The proposed scheme is an extension of the proposal
of ref. [W. Son, M. S. Kim, J. Lee, and D. Ahn, J. Mod. Opt. 49, 1739 (2002)],
where the possibility of entangling two remote qubits using a bipartite
continuous variable state was examined. While the global negativity detects the
free entanglement of the three atom mixed state, the bound entanglement is
detected by the negativity calculated from pure state decomposition of the
state operator. The partial negativities calculated by selective partial
transposition of the three atom mixed state detect the pairwise entanglement of
qubit pairs A1B, A2B, and A1A2. The entanglement of three atoms is found to be
W-like, no GHZ like quantum correlations being generated.


title:
A student designed experiment measuring the speed of sound as a function
  of altitude

abstract:
  Relatively inexpensive and readily commercially available equipment (such as
digital recorders, MP3 portable speakers and tie-pin microphones), allowed a
team of students from McNeese State University to measure the speed of sound in
the atmosphere as a function of altitude. The experiment was carried as a
payload (in the context of a NASA funded student program called La-ACES) on a
high altitude balloon that reached a maximum altitude of 101,000 feet. Not
withstanding substantial environmental noise, our particular experimental
design allowed for the filtering of the signal out of the noise, thus achieving
remarkable accuracy and precision. The speed of sound measurement was then used
to set limits on the abundances of the main molecular components of the
atmosphere (diatomic nitrogen and oxygen). Bayesian analysis was used to set
meaningful values on the uncertainty of our limits. It is our experience that
students find intutive and appealing this type of probability method.


title:
Properties and Chemical Evolution of the M31 Disk: Comparison with the
  Milky Way

abstract:
  By adopting the chemical evolution model of the Milky Way disk, we have
studied the star formation and chemical evolution history for M31 galaxy disk.
We mainly concentrated on the global properties of the M31 disk. The model has
been scaled to the related disk parameters, mainly the disk scale length and
total disk baryon mass of M31, which we have adopted to be $r_d$=5.5kpc and
$M_{tot} = 7\times 10^{10}$ \ms. It is found that, when the classical Kennicutt
star formation law was applied, the obtained radial profiles of gas surface
density and star formation rate (SFR) have great difference from the observed
results in M31 disk. Then we have adopted modified SFR as we did for the Milky
Way galaxy, that is the SFR is radial dependent. Detailed calculations show
that by adjusting the star formation efficiency, it is possible to get
reasonable gas and abundance profiles, but the total disk SFR is a factor of
2-3 higher than that estimated from observations. And also the predicted SFR
radial profile is also much higher than what GALEX observed in the outer part.
Possible reasons could be that the M31 disk has been interacted by other
factors which seriously altered the star formation history, or the observed SFR
is underestimated due to inappropriate extinction correction.


title: Relativity of musical mood

abstract:
  A combination of three or more tones played together is called a chord. In
the chromatic scale, chords which are consonant are of particular interest and
can be divided into several groups, two main ones being the major and minor
chords. This paper shows that if three sounds are produced by three spatially
separated sources, a "happy" sounding major chord can be observed as its "sad"
sounding counterpart depending on the observer's velocity - a consequence of
the well known Doppler effect. The analysis is further extended to show that
almost any triad may be observed by choosing an appropriate frame of reference,
and several interesting symmetries, asymmetries and features of the system are
discussed. Finally, the possibility of applications of this effect in the music
performance and creation in the context of "interactive listener" is discussed
and suggestions for overcoming some technical difficulties are proposed.


title: Statistical switching kinetics in ferroelectrics

abstract:
  By assuming a more realistic nucleation and polarization reversal scenario we
build a new statistical switching model for ferroelectrics, which is different
from either the Kolmogorov-Avrami-Ishibashi (KAI) model or the
Nucleation-Limited-Switching (NLS) model. After incorporating a time-dependent
depolarization field this model gives a good description about the retardation
behavior in polycrystalline thin films at medium or low fields, which can not
be described by the traditional KAI model. This model predicts correctly n=1
for polycrystalline thin films at high Eappl or ceramic bulks in the ideal
case.


title:
Terahertz Metamaterials with Semiconductor Split-Ring Resonators for
  Magnetostatic Tunability

abstract:
  We studied a metasurface constituted as a periodic array of semiconductor
split-ring resonators. The resonance frequencies of the metasurface excited by
normally incident light were found to be continuously tunable in the terahertz
regime through an external magnetostatic field of suitable orientation. As such
metasurfaces can be assembled into 3D metamaterials, the foregoing conclusion
also applies to metamaterials comprising semiconductor split-ring resonators.


title: Hybrid Keyword Search Auctions

abstract:
  Search auctions have become a dominant source of revenue generation on the
Internet. Such auctions have typically used per-click bidding and pricing. We
propose the use of hybrid auctions where an advertiser can make a
per-impression as well as a per-click bid, and the auctioneer then chooses one
of the two as the pricing mechanism. We assume that the advertiser and the
auctioneer both have separate beliefs (called priors) on the click-probability
of an advertisement. We first prove that the hybrid auction is truthful,
assuming that the advertisers are risk-neutral. We then show that this auction
is superior to the existing per-click auction in multiple ways: 1) It takes
into account the risk characteristics of the advertisers. 2) For obscure
keywords, the auctioneer is unlikely to have a very sharp prior on the
click-probabilities. In such situations, the hybrid auction can result in
significantly higher revenue. 3) An advertiser who believes that its
click-probability is much higher than the auctioneer's estimate can use
per-impression bids to correct the auctioneer's prior without incurring any
extra cost. 4) The hybrid auction can allow the advertiser and auctioneer to
implement complex dynamic programming strategies. As Internet commerce matures,
we need more sophisticated pricing models to exploit all the information held
by each of the participants. We believe that hybrid auctions could be an
important step in this direction.


title: Differential Tannakian Categories

abstract:
  We define a differential Tannakian category and show that under a natural
assumption it has a fibre functor. If in addition this category is neutral,
that is, the target category for the fibre functor are finite dimensional
vector spaces over the base field, then it is equivalent to the category of
representations of a (pro-)linear differential algebraic group. Our treatment
of the problem is via differential Hopf algebras and Deligne's fibre functor
construction.


title:
Doping dependent charge transfer gap and realistic electronic model of
  n-type cuprate superconductors

abstract:
  Based on the analysis of the measurement data of angle-resolved photoemission
spectroscopy (ARPES) and optics, we show that the charge transfer gap is
significantly smaller than the optical one and is reduced by doping in electron
doped cuprate superconductors. This leads to a strong charge fluctuation
between the Zhang-Rice singlet and the upper Hubbard bands. The basic model for
describing this system is a hybridized two-band $t$-$J$ model. In the symmetric
limit where the corresponding intra- and inter-band hopping integrals are equal
to each other, this two-band model is equivalent to the Hubbard model with an
antiferromagnetic exchange interaction (i.e. the $t$-$U$-$J$ model). The
mean-field result of the $t$-$U$-$J$ model gives a good account for the doping
evolution of the Fermi surface and the staggered magnetization.


title: Detection of the spectral binary (SB2) nature of BD-6^o1178

abstract:
  BD-6^o1178 identified with the infrared source IRAS05238-0626 is shown for
the first time to be a spectroscopic binary (SB2) by analyzing the
high-resolution spectra taken with the NES echelle spectrograph of the 6-m
telescope. The components of the binary have close spectral types and
luminosity classes: F5IV-III and F3V. The heliocentric radial velocities are
measured for both components at four observing moments in 2004-2005. Both stars
have close rotation velocities, which are equal to 24 and 19km/s. We do not
confirm the classification of BD-6^o1178 as a supergiant in the transition
stage of becoming a planetary nebula. BD-6^o1178 probably is a young pre-MS
stars. It is possibly a member of the 1c subgroup of the OriOB1 association.


abstract:
  The intersection of two Steiner triple systems (X,A) and (X,B) is the set A
intersect B. The fine intersection problem for Steiner triple systems is to
determine for each v, the set I(v), consisting of all possible pairs (m,n) such
that there exist two Steiner triple systems of order v whose intersection has n
blocks over m points. We show that for v = 1 or 3 (mod 6), |I(v)| = Omega(v^3),
where previous results only imply that |I(v)| = Omega(v^2).


title: The effect of quantum memory on quantum games

abstract:
  We study quantum games with correlated noise through a generalized
quantization scheme. We investigate the effects of memory on quantum games,
such as Prisoner's Dilemma, Battle of the Sexes and Chicken, through three
prototype quantum-correlated channels. It is shown that the quantum player
enjoys an advantage over the classical player for all nine cases considered in
this paper for the maximally entangled case. However, the quantum player can
also outperform the classical player for subsequent cases that can be noted in
the case of the Battle of the Sexes game. It can be seen that the Nash
equilibria do not change for all the three games under the effect of memory.


title: Simulations and Experiments on Polarisation Squeezing in Optical Fibre

abstract:
  We investigate polarisation squeezing of ultrashort pulses in optical fibre,
over a wide range of input energies and fibre lengths. Comparisons are made
between experimental data and quantum dynamical simulations, to find good
quantitative agreement. The numerical calculations, performed using both
truncated Wigner and exact $+P$ phase-space methods, include nonlinear and
stochastic Raman effects, through coupling to phonons variables. The
simulations reveal that excess phase noise, such as from depolarising GAWBS,
affects squeezing at low input energies, while Raman effects cause a marked
deterioration of squeezing at higher energies and longer fibre lengths. The
optimum fibre length for maximum squeezing is also calculated.


title: Relativistic stars in f(R) gravity, and absence thereof

abstract:
  Several f(R) modified gravity models have been proposed which realize the
correct cosmological evolution and satisfy solar system and laboratory tests.
Although nonrelativistic stellar configurations can be constructed, we argue
that relativistic stars cannot be present in such f(R) theories. This problem
appears due to the dynamics of the effective scalar degree of freedom in the
strong gravity regime. Our claim thus raises doubts on the viability of f(R)
models.


title:
Very Low-Mass Objects in the Coronet Cluster: The Realm of the
  Transition Disks

abstract:
  We present optical and IR spectra of a set of low-mass stars and brown dwarfs
in the Coronet cluster (aged ~1Myr), obtained with the multifiber spectrograph
FLAMES/VLT and IRS/Spitzer. The optical spectra reveal spectral types between
M1 and M7.5, confirm the youth of the objects (via Li 6708 A absorption), and
show the presence of accretion (via Halpha) and shocks (via forbidden line
emission). The IRS spectra, together with IR photometry from the IRAC/MIPS
instruments on Spitzer and 2MASS, confirm the presence of IR excesses
characteristic of disks around ~70% of the objects. Half of the disks do not
exhibit any silicate emission, or present flat features characteristic of large
grains. The rest of the disks show silicate emission typical of amorphous and
crystalline silicate grains a few microns in size. About 50% of the objects
with disks do not show near-IR excess emission, having "transitional" disks,
according to their classical definition. This is a very high fraction for such
a young cluster. The large number of "transitional" disks suggests lifetimes
comparable to the lifetimes of typical optically thick disks. Therefore, these
disks may not be in a short-lived phase, intermediate between Class II and
Class III objects. The median spectral energy distribution of the disks in the
Coronet cluster is also closer to a flat disk than observed for the disks
around solar-type stars in regions with similar age. The differences in the
disk morphology and evolution in the Coronet cluster could be related to fact
that these objects have very late spectral types compared to the solar-type
stars in other cluster studies. Finally, the optical spectroscopy reveals that
one of the X-ray sources is produced by a Herbig Haro object in the cloud.


title: Approximate volume and integration for basic semi-algebraic sets

abstract:
  Given a basic compact semi-algebraic set $\K\subset\R^n$, we introduce a
methodology that generates a sequence converging to the volume of $\K$. This
sequence is obtained from optimal values of a hierarchy of either semidefinite
or linear programs. Not only the volume but also every finite vector of moments
of the probability measure that is uniformly distributed on $\K$ can be
approximated as closely as desired, and so permits to approximate the integral
on $\K$ of any given polynomial; extension to integration against some weight
functions is also provided. Finally, some numerical issues associated with the
algorithms involved are briefly discussed.


title: Nonlinear molecular excitations in a completely inhomogeneous DNA chain

abstract:
  We study the nonlinear dynamics of a completely inhomogeneous DNA chain which
is governed by a perturbed sine-Gordon equation. A multiple scale perturbation
analysis provides perturbed kink-antikink solitons to represent open state
configuration with small fluctuation. The perturbation due to inhomogeneities
changes the velocity of the soliton. However, the width of the soliton remains
constant.


title: Regularity conditions at spatial infinity revisited

abstract:
  The regular finite initial value problem at infinity is used to obtain
regularity conditions on the freely specifiable parts of initial data for the
vacuum Einstein equations with non-vanishing second fundamental form. These
conditions ensure that the solutions of the propagation equations implied by
the conformal Einstein equations at the cylinder at spatial infinity extend
smoothly (and in fact analytically) through the critical sets where spatial
infinity touches null infinity. In order to ease the analysis the conformal
metric is assumed to be analytic, although the results presented here could be
generalised to a setting where the conformal metric is only smooth. The
analysis given here is a generalisation of the analysis on the regular finite
initial value problem first carried out by Friedrich, for initial data sets
with non-vanishing second fundamental form.


title: Space-Time Diffeomorphisms in Noncommutative Gauge Theories

abstract:
  In previous work [Rosenbaum M. et al., J. Phys. A: Math. Theor. 40 (2007),
10367-10382, hep-th/0611160] we have shown how for canonical parametrized field
theories, where space-time is placed on the same footing as the other fields in
the theory, the representation of space-time diffeomorphisms provides a very
convenient scheme for analyzing the induced twisted deformation of these
diffeomorphisms, as a result of the space-time noncommutativity. However, for
gauge field theories (and of course also for canonical geometrodynamics) where
the Poisson brackets of the constraints explicitely depend on the embedding
variables, this Poisson algebra cannot be connected directly with a
representation of the complete Lie algebra of space-time diffeomorphisms,
because not all the field variables turn out to have a dynamical character
[Isham C.J., Kuchar K.V., Ann. Physics 164 (1985), 288-315, 316-333].
Nonetheless, such an homomorphic mapping can be recuperated by first modifying
the original action and then adding additional constraints in the formalism in
order to retrieve the original theory, as shown by Kuchar and Stone for the
case of the parametrized Maxwell field in [Kuchar K.V., Stone S.L., Classical
Quantum Gravity 4 (1987), 319-328]. Making use of a combination of all of these
ideas, we are therefore able to apply our canonical reparametrization approach
in order to derive the deformed Lie algebra of the noncommutative space-time
diffeomorphisms as well as to consider how gauge transformations act on the
twisted algebras of gauge and particle fields. Thus, hopefully, adding
clarification on some outstanding issues in the literature concerning the
symmetries for gauge theories in noncommutative space-times.


title:
Challenge on the Astrophysical R-process Calculation with Nuclear Mass
  Models

abstract:
  Our understanding of the rapid neutron capture nucleosynthesis process in
universe depends on the reliability of nuclear mass predictions. Initiated by
the newly developed mass table in the relativistic mean field theory (RMF), in
this paper the influence of mass models on the $r$-process calculations is
investigated assuming the same astrophysical conditions. The different model
predictions on the so far unreachable nuclei lead to significant deviations in
the calculated r-process abundances.


title:
Interacting particles system revisited in the framework of the
  q-deformed algebra

abstract:
  We discuss the possibility of interpreting a q-deformed non-interacting
system as incorporating the effects of interactions among its particles. This
can be accomplished, for instance, in an ensemble of $q$-Bosons by means of the
virial expansion of a real gas in powers of the deformed parameter. The lowest
order virial coefficient reduces to the case of the standard, non-interacting
Bose gas, while the higher order virial coefficients contain effects arising
from the interaction. The same picture can be drawn in a quantum mechanical
system where it is shown that the q-deformed momentum can be expanded in a
series contains high-order powers of the standard quantum phase-space
variables. Motivated by this result, we introduce, in the classical framework,
a transformation relating the momentum of a free system with the momentum of an
interacting system. It is shown that the canonical quantization applied to the
interacting system imply a q-deformed quantization for the free system.

categories: cond-mat.stat-mech hep-th math-ph math.MP math.QA


title:
Primordial massive supernovae as the first molecular factories in the
  early universe

abstract:
  We study the ejecta chemistry of a zero-metallicity progenitor, massive,
supernova using a novel approach based on chemical kinetics. Species considered
span the range of simple, di-atomic molecules such as CO or SiO to more complex
species involved in dust nucleation processes. We describe their formation from
the gas phase including all possible relevant chemical processes and apply it
to the ejecta of a primordial 170 Msun supernova. Two ejecta cases are
explored: full mixing of the heavy elements, and a stratified ejecta reflecting
the progenitor nucleosynthesis. Penetration of hydrogen from the progenitor
envelope is considered. We show that molecules form very efficiently in the
ejecta of primordial supernovae whatever the level of mixing and account for 13
to 34% of the total progenitor mass, equivalent to 21 to 57 Msun of the ejecta
material in molecular form. The chemical nature of molecules depends on mixing
of heavy elements and hydrogen in the ejecta. Species produced include O2, CO,
CO2, SiS, SO, SiO and H2. Consequently, molecules can be used as observational
tracers of supernova mixing after explosion. We conclude that primordial
massive supernovae are the first molecule providers to the early universe.


title: On the kinematics of the centre of charge of a spinning particle

abstract:
  In particle physics, most of the classical models consider that the centre of
mass and centre of charge of an elementary particle, are the same point. This
presumes some particular relationship between the charge and mass distribution,
a feature which cannot be checked experimentally. In this paper we give three
different kinds of arguments suggesting that, if assumed different points, the
centre of charge of an elementary spinning particle moves in a helical motion
at the speed of light, and it thus satisfies, in general, a fourth order
differential equation. If assumed a kind of rigid body structure, it is
sufficient the description of the centre of charge to describe also the
evolution of the centre of mass and the rotation of the body. This assumption
of a separation betwen the centre of mass and centre of charge gives a
contribution to the spin of the system and also justifies the existence of a
magnetic moment produced by the relative motion of the centre of charge. This
corresponds to an improved model of a charged elementary particle, than the
point particle case. This means that a Lagrangian formalism for describing
elementary spinning particles has to depend, at least, up to the acceleration
of the position of the charge, to properly obtain fourth order dynamical
equations. This result is compared with the description of a classical Dirac
particle obtained from a general Lagrangian formalism for describing spinning
particles.


title: Solid behavior of anisotropic rigid frictionless bead assemblies

abstract:
  We investigate the structure and mechanical behavior of assemblies of
frictionless, nearly rigid equal-sized beads, in the quasistatic limit, by
numerical simulation. Three different loading paths are explored: triaxial
compression, triaxial extension and simple shear. Generalizing recent results
[1], we show that the material, despite rather strong finite sample size
effects, is able to sustain a finite deviator stress in the macroscopic limit,
along all three paths, without dilatancy. The shape of the yield surface is
adequately described by a Lade-Duncan (rather than Mohr-Coulomb) criterion.
While scalar state variables keep the same values as in isotropic systems,
fabric and force anisotropies are each characterized by one parameter and are
in one-to-one correspondence with principal stress ratio along all three
loading paths.The anisotropy of the pair correlation function extends to a
distance between bead surfaces on the order of 10% of the diameter. The tensor
of elastic moduli is shown to possess a nearly singular, uniaxial structure
related to stress anisotropy. Possible stress-strain relations in monotonic
loading paths are also discussed.


title: Higgs Physics at the LHC: Some Theory Aspects

abstract:
  In these lecture notes we review some prospect for the upcoming LHC
experiments in view of the exploration of the Standard Model (SM) or its
minimal Supersymmetric extension (MSSM). We focus on some theoretical aspects
concerning the Higgs sector of the two models. We give results for the
precision observables M_W and m_t and their impact on the indirect
determination of the Higgs sector. We furthermore review some prospects for the
direct measurements in the SM and MSSM Higgs sector.


title: The Dark Energy Survey Data Management System

abstract:
  The Dark Energy Survey collaboration will study cosmic acceleration with a
5000 deg2 griZY survey in the southern sky over 525 nights from 2011-2016. The
DES data management (DESDM) system will be used to process and archive these
data and the resulting science ready data products. The DESDM system consists
of an integrated archive, a processing framework, an ensemble of astronomy
codes and a data access framework. We are developing the DESDM system for
operation in the high performance computing (HPC) environments at NCSA and
Fermilab. Operating the DESDM system in an HPC environment offers both speed
and flexibility. We will employ it for our regular nightly processing needs,
and for more compute-intensive tasks such as large scale image coaddition
campaigns, extraction of weak lensing shear from the full survey dataset, and
massive seasonal reprocessing of the DES data. Data products will be available
to the Collaboration and later to the public through a virtual-observatory
compatible web portal. Our approach leverages investments in publicly available
HPC systems, greatly reducing hardware and maintenance costs to the project,
which must deploy and maintain only the storage, database platforms and
orchestration and web portal nodes that are specific to DESDM. In Fall 2007, we
tested the current DESDM system on both simulated and real survey data. We used
Teragrid to process 10 simulated DES nights (3TB of raw data), ingesting and
calibrating approximately 250 million objects into the DES Archive database. We
also used DESDM to process and calibrate over 50 nights of survey data acquired
with the Mosaic2 camera. Comparison to truth tables in the case of the
simulated data and internal crosschecks in the case of the real data indicate
that astrometric and photometric data quality is excellent.


title: Adiabatic preparation without Quantum Phase Transitions

abstract:
  Many physically interesting models show a quantum phase transition when a
single parameter is varied through a critical point, where the ground state and
the first excited state become degenerate. When this parameter appears as a
coupling constant, these models can be understood as straight-line
interpolations between different Hamiltonians $H_{\rm I}$ and $H_{\rm F}$. For
finite-size realizations however, there will usually be a finite energy gap
between ground and first excited state. By slowly changing the coupling
constant through the point with the minimum energy gap one thereby has an
adiabatic algorithm that prepares the ground state of $H_{\rm F}$ from the
ground state of $H_{\rm I}$. The adiabatic theorem implies that in order to
obtain a good preparation fidelity the runtime $\tau$ should scale with the
inverse energy gap and thereby also with the system size. In addition, for open
quantum systems not only non-adiabatic but also thermal excitations are likely
to occur. It is shown that -- using only local Hamiltonians -- for the 1d
quantum Ising model and the cluster model in a transverse field the
conventional straight line path can be replaced by a series of straight-line
interpolations, along which the fundamental energy gap is always greater than a
constant independent on the system size. The results are of interest for
adiabatic quantum computation since strong similarities between adiabatic
quantum algorithms and quantum phase transitions exist.


title: Reverse Hall-Petch effect in ultra nanocrystalline diamond

abstract:
  We present atomistic simulations for the mechanical response of ultra
nanocrystalline diamond, a polycrystalline form of diamond with grain diameters
of the order of a few nm. We consider fully three-dimensional model structures,
having several grains of random sizes and orientations, and employ
state-of-the-art Monte Carlo simulations. We calculate structural properties,
elastic constants and the hardness of the material; our results compare well
with experimental observations for this material. Moreover, we verify that this
material becomes softer at small grain sizes, in analogy to the observed
reversal of the Hall-Petch effect in various nanocrystalline metals. The effect
is attributed to the large concentration of grain boundary atoms at smaller
grain sizes. Our analysis yields scaling relations for the elastic constants as
a function of the average grain size.


title:
Polar transform of Spacelike isothermic surfaces in 4-dimensional
  Lorentzian space forms

abstract:
  The conformal geometry of spacelike surfaces in 4-dimensional Lorentzian
space forms has been studied by the authors in a previous paper, where the
so-called polar transform was introduced. Here it is shown that this transform
preserves spacelike conformal isothermic surfaces. We relate this new transform
with the known transforms (Darboux transform and spectral transform) of
isothermic surfaces by establishing the permutability theorems.


title: Current-induced domain-wall motion in synthetic antiferromagnets

abstract:
  Domain-wall magnetoresistance and low-frequency noise have been studied in
epitaxial antiferromagnetically-coupled [Fe/Cr(001)]_10 multilayers and
ferromagnetic Co line structures as a function of DC current intensity. In
[Fe/Cr(001)]_10 multilayers a transition from excess to suppressed domain-wall
induced 1/f noise above current densities of j_c ~ 2*10^5 A/cm^2 has been
observed. In ferromagnetic Co line structures the domain wall related noise
remains qualitatively unchanged up to current densities exceeding 10^6A/cm^2.
Theoretical estimates of the critical current density for a synthetic Fe/Cr
antiferromagnet suggest that this effect may be attributed to current-induced
domain-wall motion that occurs via spin transfer torques.


title:
1/N phenomenon for some symmetry classes of the odd alternating sign
  matrices

abstract:
  We consider the alternating sign matrices of the odd order that have some
kind of central symmetry. Namely, we deal with matrices invariant under the
half-turn, quarter-turn and flips in both diagonals. In all these cases, there
are two natural structures in the centre of the matrix. For example, for the
matrices invariant under the half-turn the central element is equal $\pm 1$. It
was recently found that $A^+_{HT}(2m+1)/A^-_{HT}(2m+1)$=(m+1)/m. We conjecture
that similar very simple relations are valid in the two remaining cases.


title: Fundamentals and applications of isotope effect in modern technology

abstract:
  In this short review I discuss the effect of isotopic mass and isotopic
disorder on the properties (vibrational, elastic, thermal and optical) of
different crystals.


title: The Second-Generation Guide Star Catalog: Description and Properties

abstract:
  The GSC-II is an all-sky database of objects derived from the uncompressed
DSS that the STScI has created from the Palomar and UK Schmidt survey plates
and made available to the community. Like its predecessor (GSC-I), the GSC-II
was primarily created to provide guide star information and observation
planning support for HST. This version, however, is already employed at some of
the ground-based new-technology telescopes such as GEMINI, VLT, and TNG, and
will also be used to provide support for the JWST and Gaia space missions as
well as LAMOST, one of the major ongoing scientific projects in China. Two
catalogs have already been extracted from the GSC-II database and released to
the astronomical community. A magnitude-limited (R=18.0) version, GSC2.2, was
distributed soon after its production in 2001, while the GSC2.3 release has
been available for general access since 2007.
  The GSC2.3 catalog described in this paper contains astrometry, photometry,
and classification for 945,592,683 objects down to the magnitude limit of the
plates. Positions are tied to the ICRS; for stellar sources, the all-sky
average absolute error per coordinate ranges from 0.2" to 0.28" depending on
magnitude. When dealing with extended objects, astrometric errors are 20% worse
in the case of galaxies and approximately a factor of 2 worse for blended
images. Stellar photometry is determined to 0.13-0.22 mag as a function of
magnitude and photographic passbands (B,R,I). Outside of the galactic plane,
stellar classification is reliable to at least 90% confidence for magnitudes
brighter than R=19.5, and the catalog is complete to R=20.


title:
Classical big-bounce cosmology: dynamical analysis of a homogeneous and
  irrotational Weyssenhoff fluid

abstract:
  A dynamical analysis of an effective homogeneous and irrotational Weyssenhoff
fluid in general relativity is performed using the 1+3 covariant approach that
enables the dynamics of the fluid to be determined without assuming any
particular form for the space-time metric. The spin contributions to the field
equations produce a bounce that averts an initial singularity, provided that
the spin density exceeds the rate of shear. At later times, when the spin
contribution can be neglected, a Weyssenhoff fluid reduces to a standard
cosmological fluid in general relativity. Numerical solutions for the time
evolution of the generalised scale factor in spatially-curved models are
presented, some of which exhibit eternal oscillatory behaviour without any
singularities. In spatially-flat models, analytical solutions for particular
values of the equation-of-state parameter are derived. Although the scale
factor of a Weyssenhoff fluid generically has a positive temporal curvature
near a bounce, it requires unreasonable fine tuning of the equation-of-state
parameter to produce a sufficiently extended period of inflation to fit the
current observational data.


title: Spin currents and spin superfluidity

abstract:
  The present review analyzes and compares various types of dissipationless
spin transport: (1) Superfluid transport, when the spin-current state is a
metastable state (a local but not the absolute minimum in the parameter space).
(2) Ballistic spin transport, when spin is transported without losses simply
because sources of dissipation are very weak. (3) Equilibrium spin currents,
i.e., genuine persistent currents. (4) Spin currents in the spin Hall effect.
Since superfluidity is frequently connected with Bose condensation, recent
debates about magnon Bose condensation are also reviewed. For any type of spin
currents simplest models were chosen for discussion in order to concentrate on
concepts rather than details of numerous models. The various hurdles on the way
of using the concept of spin current (absence of the spin-conservation law,
ambiguity of spin current definition, etc.) were analyzed. The final conclusion
is that the spin-current concept can be developed in a fully consistent manner,
and is a useful language for description of various phenomena in spin dynamics.


title:
Extracting Galaxy Cluster Gas Inhomogeneity from X-ray Surface
  Brightness: A Statistical Approach and Application to Abell 3667

abstract:
  Our previous analysis indicates that small-scale fluctuations in the
intracluster medium (ICM) from cosmological hydrodynamic simulations follow the
lognormal distribution. In order to test the lognormal nature of the ICM
directly against X-ray observations of galaxy clusters, we develop a method of
extracting statistical information about the three-dimensional properties of
the fluctuations from the two-dimensional X-ray surface brightness.
  We first create a set of synthetic clusters with lognormal fluctuations.
Performing mock observations of these synthetic clusters, we find that the
resulting X-ray surface brightness fluctuations also follow the lognormal
distribution fairly well. Systematic analysis of the synthetic clusters
provides an empirical relation between the density fluctuations and the X-ray
surface brightness. We analyze \chandra observations of the galaxy cluster
Abell 3667, and find that its X-ray surface brightness fluctuations follow the
lognormal distribution. While the lognormal model was originally motivated by
cosmological hydrodynamic simulations, this is the first observational
confirmation of the lognormal signature in a real cluster. Finally we check the
synthetic cluster results against clusters from cosmological hydrodynamic
simulations. As a result of the complex structure exhibited by simulated
clusters, the empirical relation shows large scatter. Nevertheless we are able
to reproduce the true value of the fluctuation amplitude of simulated clusters
within a factor of two from their X-ray surface brightness alone.
  Our current methodology combined with existing observational data is useful
in describing and inferring the statistical properties of the three dimensional
inhomogeneity in galaxy clusters.


title: Arbitrage and deflators in illiquid markets

abstract:
  This paper presents a stochastic model for discrete-time trading in financial
markets where trading costs are given by convex cost functions and portfolios
are constrained by convex sets. The model does not assume the existence of a
cash account/numeraire. In addition to classical frictionless markets and
markets with transaction costs or bid-ask spreads, our framework covers markets
with nonlinear illiquidity effects for large instantaneous trades. In the
presence of nonlinearities, the classical notion of arbitrage turns out to have
two equally meaningful generalizations, a marginal and a scalable one. We study
their relations to state price deflators by analyzing two auxiliary market
models describing the local and global behavior of the cost functions and
constraints.


title:
Thermotunnel refrigerator with vacuum/insulator tunnel barrier: A
  theoretical analysis

abstract:
  The authors use two insulator layers in thermotunnel refrigerator to modify
the shape of the tunneling barrier so that electrons with high kinetic energy
pass it with increased probability. Theoretical analysis show that the overall
tunneling current between the electrodes contains an increased number of high
kinetic energy electrons and a reduced number of low energy ones, leading to
high efficiency. The particular case of vacuum gap and solid insulator layer is
calculated using digital methods. Efficiency remains high in the wide range of
the emitter electric field. The cooling coefficient is found to be as high as
40%-50% in the wide range of the emitter electric field.


title: Vector models for dark energy

abstract:
  We explore the possibility that the present stage of accelerated expansion of
the universe is due to the presence of a cosmic vector field. We show that
vector theories allow for the generation of an accelerated phase without the
introduction of potential terms or unnatural scales in the Lagrangian. We
propose a particular model with the same number of parameters as LCDM and
excellent fits to SNIa data. The model is scaling during radiation era, with
natural initial conditions, thus avoiding the cosmic coincidence problem.
Upcoming observations will be able to clearly discriminate it from standard
LCDM cosmology


title: Enhancing the Detection of Natural Thermal Entanglement with Disorder

abstract:
  Physical systems have some degree of disorder present in them. We discuss how
to treat natural, thermal entanglement in any random macroscopic system from
which a thermodynamic witness bounded by a constant can be found. We propose
that functional many-body perturbation theory be applied to allow either a
quenched or an annealed average over the disorder to be taken. We find when
considering the example of an XX Heisenberg spin chain with a random coupling
strength, that the region of natural entanglement detected by both witnesses
can be enhanced by the disorder.


title: High-Temperature Superconductivity in Eu0.5K0.5Fe2As2

abstract:
  Subsequent to our recent report of SDW type transition at 190 K and
antiferromagnetic order below 20 K in EuFe2As2, we have studied the effect of
K-doping on the SDW transition at high temperature and AF order at low
temperature. 50% K doping suppresses the SDW transition and in turn gives rise
to high-temperature superconductivity below T_c = 32 K, as observed in the
electrical resistivity, AC susceptibility as well as magnetization. A well
defined anomaly in the specific heat provides additional evidence for bulk
superconductivity.


title: Absence of diffusion in certain random lattices: Numerical evidence

abstract:
  We demonstrate, by solving numerically the time-dependent Schroedinger
equation, the physical character of electron localization in a disordered
two-dimensional lattice. We show, in agreement with the prediction of P. W.
Anderson, that the disorder prevents electron diffusion. The electron becomes
spatially localized in a specific area of the system. Our numerical analysis
confirms that the electron localization is a quantum effect caused by the wave
character of electron propagation and has no analogy in classical mechanics.


title: Generalized kinematical symmetries of quantum phase space

abstract:
  Continuous symmetries generated with observables of a quantum theory in the
Minkowski spacetime are discussed. An example of an originated in this way
algebra of observables is the algebra of observables of the canonical quantum
theory, that is contained the Lorentz group algebra and the Heisenberg algebra
of phase space operators. In the general case commutation relations between
observables depend on c, h and additional fundamental constants. Free field
equations are considered, which are invariant with respect to generalized
kinematical symmetries of the quantum phase space.


title: Space-Time Earthquake Prediction: the Error Diagrams

abstract:
  The quality of earthquake prediction is usually characterized by a
two-dimensional diagram 'n' vs. 'tau', where 'n' is the rate of
failures-to-predict and 'tau' is a characteristic of space- time alarm. Unlike
the time prediction case, the quantity 'tau' is not defined uniquely, so that
the properties of the (n,tau) diagram require a theoretical analysis, which is
the main goal of the present study. This note is based on a recent paper by
Molchan and Keilis-Borok in GJI, 173 (2008), 1012-1017.


title:
First principles studies of SnTiO3 perovskite as a potential
  ferroelectric material

abstract:
  In the context of the search for environment-respectful, lead- and bismuth-
free chemical compounds for devices such as actuators, SnTiO3 (ST) is
investigated from first principles within DFT. Full geometry optimization
provides a stable tetragonal structure relative to cubic one. From the equation
of state the equilibrium volume of SnTiO3 is found smaller than ferroelectric
PbTiO3 (PT) in agreement with a smaller Sn2+ radius. While ionic displacements
exhibit similar trends between ST and PT a larger tetragonality (c/a ratio) for
ST results in a larger polarization, PST = 1.1 C.m2. The analysis of the
electronic band structure detailing the Sn-O and Ti-O interactions points to a
differentiated chemical bonding and a reinforcement of the covalent bonding
with respect to Pb homologue.