title:
Astrophysical Relevance of Storage-Ring Electron-Ion Recombination
  Experiments

abstract:
  The relevance of storage-ring electron-ion recombination experiments for
astrophysics is outlined. In particular, the role of low-energy
dielectronic-recombination resonances is discussed. A bibliographic compilation
of electron-ion recombination measurements with cosmically abundant ions is
provided.


title: Quarkonium production and polarisation with early data at ATLAS

abstract:
  One of the first physics results to come out of ATLAS will be an analysis of
J/psi and Upsilon production at 14 TeV. I give an overview of the motivation
for looking at the theoretical model underlying quarkonium production, ATLAS
expected performance and rates for quarkonium reconstruction and ability to
separate out various proposed production models with a view to improving our
understanding of QCD.


title: Numerical evaluation of the Casimir interaction between cylinders

abstract:
  We numerically evaluate the Casimir interaction energy for configurations
involving two perfectly conducting eccentric cylinders and a cylinder in front
of a plane. We consider in detail several special cases. For quasi-concentric
cylinders, we analyze the convergence of a perturbative evaluation based on
sparse matrices. For concentric cylinders, we obtain analytically the
corrections to the proximity force approximation up to second order, and we
present an improved numerical procedure to evaluate the interaction energy at
very small distances. Finally, we consider the configuration of a cylinder in
front of a plane. We first show numerically that, in the appropriate limit, the
Casimir energy for this configuration can be obtained from that of two
eccentric cylinders. Then we compute the interaction energy at small distances,
and compare the numerical results with the analytic predictions for the first
order corrections to the proximity force approximation.


title:
Debye Sources and the Numerical Solution of the Time Harmonic Maxwell
  Equations

abstract:
  In this paper, we develop a new representation for outgoing solutions to the
time harmonic Maxwell equations in unbounded domains in $\bbR^3.$ This
representation leads to a Fredholm integral equation of the second kind for
solving the problem of scattering from a perfect conductor, which does not
suffer from spurious resonances or low frequency breakdown, although it
requires the inversion of the scalar surface Laplacian on the domain boundary.
In the course of our analysis, we give a new proof of the existence of
non-trivial families of time harmonic solutions with vanishing normal
components that arise when the boundary of the domain is not simply connected.
We refer to these as $k$-Neumann fields, since they generalize, to non-zero
wave numbers, the classical harmonic Neumann fields. The existence of
$k$-harmonic fields was established earlier by Kress.


title: Elementary Charge Transfer Processes in Mesoscopic Conductors

abstract:
  We determine charge transfer statistics in a quantum conductor driven by a
time-dependent voltage and identify the elementary transport processes. At zero
temperature unidirectional and bidirectional single charge transfers occur. The
unidirectional processes involve electrons injected from the source terminal
due to excess dc bias voltage. The bidirectional processes involve
electron-hole pairs created by time-dependent voltage bias. This interpretation
is further supported by the charge transfer statistics in a multiterminal beam
splitter geometry in which injected electrons and holes can be partitioned into
different outgoing terminals. The probabilities of elementary processes can be
probed by noise measurements: the unidirectional processes set the dc noise
level while bidirectional ones give rise to the excess noise. For ac voltage
drive, the noise oscillates with increasing the driving amplitude. The
decomposition of the noise into the contributions of elementary processes
identifies the origin of these oscillations: the number of electron-hole pairs
generated per cycle increases with increasing the amplitude. The decomposition
of the noise into elementary processes is studied for different time-dependent
voltages. The method we use is also suitable for systematic calculation of
higher-order current correlators at finite temperature. We obtain current noise
power and the third cumulant in the presence of time-dependent voltage drive.
The charge transfer statistics at finite temperature can be interpreted in
terms of multiple charge transfers with probabilities which depend on energy
and temperature.


title: Number of the QCD critical points with neutral color superconductivity

abstract:
  We investigate the effect of the electric-charge neutrality in
  $\beta$ equilibrium on the chiral phase transition by solving the chiral and
diquark condensates in the two-flavor Nambu--Jona-Lasinio model. We demonstrate
that the electric-charge neutrality plays a similar role as the repulsive
vector interaction; they both weaken the first-order chiral phase transition in
the high-density and low-temperature region. The first-order chiral phase
transition is not affected, however, at finite temperatures where the diquark
condensate melts. In this way the chiral phase transition could be second-order
at intermediate temperatures if the diquark effects overwhelm the chiral
dynamics, while the first-order transition may survive at lower and higher
temperatures. The number of the critical points appearing on the phase diagram
can vary from zero to three, which depends on the relative strength of the
chiral and diquark couplings. We systematically study the possibility of the
phase structure with multiple QCD critical points and evaluate the Meissner
screening mass to confirm that our conclusion is not overturned by
chromomagnetic instability.


title: Beyond the rainbow: effects from pion back-coupling

abstract:
  We investigate hadronic unquenching effects in light quarks and mesons. To
this end we take into account the back-coupling of the pion onto the quark
propagator within the non-perturbative continuum framework of Schwinger-Dyson
equations (SDE) and Bethe-Salpeter equations (BSE). We improve on a previous
approach by explicitly solving both the coupled system of DSEs and BSEs in the
complex plane and the normalisation problem for Bethe-Salpeter kernels
depending on the total momentum of the meson. As a result of our study we find
considerable unquenching effects in the spectrum of light pseudoscalar, vector
and axial-vector mesons.


title:
Quasiharmonic elastic constants corrected for deviatoric thermal
  stresses

abstract:
  The quasiharmonic approximation (QHA), in its simplest form also called the
statically constrained (SC) QHA, has been shown to be a straightforward method
to compute thermoelastic properties of crystals. Recently we showed that for
non-cubic solids SC-QHA calculations develop deviatoric thermal stresses at
high temperatures. Relaxation of these stresses leads to a series of
corrections to the free energy that may be taken to any desired order, up to
self-consistency. Here we show how to correct the elastic constants obtained
using the SC-QHA. We exemplify the procedure by correcting to first order the
elastic constants of MgSiO$_3$-perovskite and MgSiO$_3$-post-perovskite, the
major phases of the Earth's lower mantle. We show that this first order
correction is quite satisfactory for obtaining the aggregated elastic averages
of these minerals and their velocities in the lower mantle. This type of
correction is also shown to be applicable to experimental measurements of
elastic constants in situations where deviatoric stresses can develop, such as
in diamond anvil cells.


title: The Corona Australis Star Forming Region

abstract:
  At a distance of about 130 pc, the Corona Australis molecular cloud complex
is one of the nearest regions with ongoing and/or recent star formation. It is
a region with highly variable extinction of up to AV~45 mag, containing, at its
core, the Coronet protostar cluster. There are now 55 known optically detected
members, starting at late B spectral types. At the opposite end of the mass
spectrum, there are two confirmed brown dwarf members and seven more candidate
brown dwarfs. The CrA region has been most widely surveyed at infrared
wavelengths, in X-rays, and in the millimeter continuum, while follow-up
observations from centimeter radio to X-rays have focused on the Coronet
cluster.


title: Equilibrium and traveling-wave solutions of plane Couette flow

abstract:
  We present ten new equilibrium solutions to plane Couette flow in small
periodic cells at low Reynolds number (Re) and two new traveling-wave
solutions. The solutions are continued under changes of Re and spanwise period.
We provide a partial classification of the isotropy groups of plane Couette
flow and show which kinds of solutions are allowed by each isotropy group. We
find two complementary visualizations particularly revealing. Suitably chosen
sections of their 3D-physical space velocity fields are helpful in developing
physical intuition about coherent structures observed in low Re turbulence.
Projections of these solutions and their unstable manifolds from their
infinite-dimensional state space onto suitably chosen 2- or 3-dimensional
subspaces reveal their interrelations and the role they play in organizing
turbulence in wall-bounded shear flows.


title: United classification of cosmic gamma-ray bursts and their counterparts

abstract:
  United classification of gamma-ray bursts and their counterparts is
established on the basis of measured characteristics: photon energy E and
emission duration T. The founded interrelation between the mentioned
characteristics of events consists in that, as the energy increases, the
duration decreases (and vice versa). The given interrelation reflects the
nature of the phenomenon and forms the E-T diagram, which represents a natural
classification of all observed events in the energy range from 10E9 to 10E-6 eV
and in the corresponding interval of durations from about 10E-2 up to 10E8 s.
The proposed classification results in the consequences, which are principal
for the theory and practical study of the phenomenon.


title: Cosmic X-ray background and Earth albedo Spectra with Swift/BAT

abstract:
  We use Swift/BAT Earth occultation data at different geomagnetic latitudes to
derive a sensitive measurement of the Cosmic X-ray background (CXB) and of the
Earth albedo emission in the 15--200 keV band. We compare our CXB spectrum with
recent (INTEGRAL, BeppoSAX) and past results (HEAO-1) and find good agreement.
Using an independent measurement of the CXB spectrum we are able to confirm our
results. This study shows that the BAT CXB spectrum has a normalization
~8(+/-3)% larger than the HEAO-1 measurement. The BAT accurate Earth albedo
spectrum can be used to predict the level of photon background for satellites
in low Earth and mid inclination orbits.


title:
Identifying Deficiencies of Standard Accretion Disk Theory: Lessons from
  a Mean-Field Approach

abstract:
  Turbulent viscosity is frequently used in accretion disk theory to replace
the microphysical viscosity in order to accomodate the observational need for
in- stabilities in disks that lead to enhanced transport. However, simply
replacing the microphysical transport coefficient by a single turbulent
transport coeffi- cient hides the fact that the procedure should formally arise
as part of a closure in which the hydrodynamic or magnetohydrodynamic equations
are averaged, and correlations of turbulent fluctuations are replaced by
transport coefficients. Here we show how a mean field approach leads quite
naturally two transport coefficients, not one, that govern mass and angular
momentum transport. In particular, we highlight that the conventional approach
suffers from a seemingly inconsistent neglect of turbulent diffusion in the
surface density equation. We constrain these new transport coefficients for
specific cases of inward, outward, and zero net mass transport. In addition, we
find that one of the new transport terms can lead to oscillations in the mean
surface density which then requires a constant or small inverse Rossby number
for disks to maintain a monotonic power-law surface density.


title: The effects of Gribov copies in 2D gauge theories

abstract:
  In previous works, we have shown that the Gribov-Zwanziger action, which
implements the restriction of the domain of integration in the path integral to
the Gribov region, generates extra dynamical effects which influence the
infrared behaviour of the gluon and ghost propagator in SU(N) Yang-Mills gauge
theories. The latter are in good agreement with the most recent lattice data
obtained at large volumes, both in 4D and in 3D. More precisely, the gluon
propagator is suppressed and does not vanish at zero momentum, while the ghost
propagator keeps a 1/p^2 behaviour for p^2\approx0. Instead, in 2D, the lattice
data revealed a vanishing zero momentum gluon propagator and an infrared
enhanced ghost, in support of the usual Gribov-Zwanziger scenario. We will now
show that the 2D version of the Gribov-Zwanziger action still gives results in
qualitative agreement with these lattice data, as the peculiar infrared nature
of 2D gauge theories precludes the analogue of the dynamical effect otherwise
present in 4D and 3D. Simultaneously, we also observe that the Gribov-Zwanziger
restriction serves as an infrared regulating mechanism.


title: Space-time sensors using multiple-wave atom levitation

abstract:
  The best clocks to date control the atomic motion by trapping the sample in
an optical lattice and then interrogate the atomic transition by shining on
these atoms a distinct laser of controlled frequency. In order to perform both
tasks simultaneously and with the same laser field, we propose to use instead
the levitation of a Bose-Einstein condensate through multiple-wave atomic
interferences. The levitating condensate experiences a coherent localization in
momentum and a controlled diffusion in altitude. The sample levitation is bound
to resonance conditions used either for frequency or for acceleration
measurements. The chosen vertical geometry solves the limitations imposed by
the sample free fall in previous optical clocks using also atomic
interferences. This configuration yields multiple-wave interferences enabling
levitation and enhancing the measurement sensitivity. This setup, analogous to
an atomic resonator in momentum space, constitutes an attractive alternative to
existing atomic clocks and gravimeters.


title: Seidel-Smith Cohomology for Tangles

abstract:
  We generalize the "symplectic Khovanov cohomology" of Seidel and Smith to
tangles using the notion of symplectic valued topological field theory
introduced by Wehrheim and Woodward.


title: The Chiral Magnetic Effect

abstract:
  Topological charge changing transitions can induce chirality in the
quark-gluon plasma by the axial anomaly. We study the equilibrium response of
the quark-gluon plasma in such a situation to an external magnetic field. To
mimic the effect of the topological charge changing transitions we will
introduce a chiral chemical potential. We will show that an electromagnetic
current is generated along the magnetic field. This is the Chiral Magnetic
Effect. We compute the magnitude of this current as a function of magnetic
field, chirality, temperature, and baryon chemical potential.


title: The Ara OB 1a Association

abstract:
  The Ara OB1a association is one of the closest sites where triggered star
formation is visible for multiple generations of massive stars. At about 1.3
kpc distance, it contains complex environments including cleared young
clusters, embedded infrared clusters, CO clouds with no evidence of star
formation, and clouds with evidence of ongoing star formation. In this review
we discuss the research on this region spanning the last half-century. It has
been proposed that the current configuration is the result of an expanding wave
of neutral gas set in motion between 10--40 million years ago in combination
with photoionization from the current epoch.


title:
Deducing the nature of dark matter from direct and indirect detection
  experiments in the absence of collider signatures of new physics

abstract:
  Despite compelling arguments that significant discoveries of physics beyond
the standard model are likely to be made at the Large Hadron Collider, it
remains possible that this machine will make no such discoveries, or will make
no discoveries directly relevant to the dark matter problem. In this article,
we study the ability of astrophysical experiments to deduce the nature of dark
matter in such a scenario. In most dark matter studies, the relic abundance and
detection prospects are evaluated within the context of some specific particle
physics model or models (e.g. supersymmetry). Here, we attempt to develop a
model-independent approach toward the phenomenology of weakly interacting
massive particles in the absence of any discoveries at the Large Hadron
Collider. In particular, we consider generic fermionic or scalar dark matter
particles with a variety of interaction forms, and calculate the corresponding
constraints from and sensitivity of direct and indirect detection experiments.
The results may provide some guidance in disentangling information from future
direct and indirect detection experiments.


title: The Embedded Massive Star Forming Region RCW 38

abstract:
  RCW~38 is a uniquely young ($<$1 Myr), embedded ($A_V \sim 10$) stellar
cluster surrounding a pair of early O stars ($\sim$O5.5) and is one of the few
regions within 2 kpc other than Orion to contain over 1000 members. X-ray and
deep near-infrared observations reveal a dense cluster with over 200 X-ray
sources and 400 infrared sources embedded in a diffuse hot plasma within a 1 pc
diameter. The central O star has evacuated its immediate surroundings of dust,
creating a wind bubble $\sim$0.1 pc in radius that is confined by the
surrounding molecular cloud, as traced by millimeter continuum and molecular
line emission. The interface between the bubble and cloud is a region of warm
dust and ionized gas, which shows evidence for ongoing star formation. Extended
warm dust is found throughout a 2--3 pc region and coincides with extended
X-ray plasma. This is evidence that the influence of the massive stars reaches
beyond the confines of the O star bubble. RCW~38 appears similar in structure
to RCW~49 and M~20 but is at an earlier evolutionary phase. RCW~38 appears to
be a blister compact H{\small II} region lying just inside the edge of a giant
molecular cloud.


title: Linear Programming Formulation of the Boolean Satisfiability Problem

abstract:
  In this paper, we present a new, graph-based modeling approach and a
polynomial-sized linear programming (LP) formulation of the Boolean
satisfiability problem (SAT). The approach is illustrated with a numerical
example.


title: On the surface of glasses

abstract:
  Dynamics near the surface of glasses is generally much faster than in the
bulk. Neglecting static perturbations of structure at the surface, we use
random first order transition theory to show the free energy barrier for
activated motion near a free surface should be half that of the bulk at the
same temperature. The increased mobility allows the surface layers to descend
much further on the energy landscape than the bulk ordinarily does. The
simplified RFOT calculation however predicts a limiting value for the
configurational entropy a vapor deposited glass may reach as a function of
deposition rate. We sketch how mode coupling effects extend the excess free
surface mobility into the bulk so that the glass transition temperature is
measurably perturbed at depths greater than the naive length scale of dynamic
cooperativity.


title: Quantum Well Based on Graphene and Narrow-Gap Semiconductors

abstract:
  We consider the energy spectrum of the planar quantum well which consisted of
two ribbons of narrow-gap semiconductors and a graphene ribbon between ones. It
is shown that the gapless mode appears only in case of inverted narrow-gap
semiconductors. Spin splitting of the energy spectrum for a nonsymmetric
quantum well is calculated taking into account a specificity of graphene. We
investigate interface states and optical transitions. It is shown that the
optical transitions are possible only with a conservation of a parity.


title: Towards Functoriality Of Spinor L-functions

abstract:
  The object of this work is the spinor L-function of degree 3 and certain
degeneration related to the functoriality principle. We study liftings of
automorphic forms on the pair of symplectic groups
$(\text{GSp}(2),\text{GSp}(4))$ to $\text{GSp}(6)$. We prove cuspidality and
demonstrate the compatibility with conjectures of Andrianov, Panchishkin,
Deligne and Yoshida. This is done on a motivic and analytic level. We discuss
an underlying torus and L-group homomorphism and put our results in the context
of the Langlands program.


title:
Anomalous dimensions of transverse-momentum dependent parton
  distribution functions

abstract:
  We discuss recent developments in the understanding of gauge-invariant
transverse-momentum dependent (TMD) parton-distribution functions (PDF). We
compute the leading-order $\overline{\text{MS}\vphantom{^1}}$-scheme anomalous
dimension of such a quantity in the light-cone gauge and show that it receives
a contribution that can be associated with a cusp obstruction at transverse
light-cone infinity. This anomalous dimension is intimately related to
expectation values composed of fields and eikonal factors along a cusped
contour and is absent in covariant gauges. The implications of these findings
are addressed and a modified definition of TMD PDFs is proposed.


title:
Correlations of Prompt and Afterglow Emission in Swift Long and Short
  Gamma Ray Bursts

abstract:
  Correlation studies of prompt and afterglow emissions from gamma-ray bursts
(GRBs) between different spectral bands has been difficult to do in the past
because few bursts had comprehensive and intercomparable afterglow
measurements. In this paper we present a large and uniform data set for
correlation analysis based on bursts detected by the Swift mission. For the
first time, short and long bursts can be analyzed and compared. It is found for
both classes that the optical, X-ray and gamma-ray emissions are linearly
correlated, but with a large spread about the correlation line; stronger bursts
tend to have brighter afterglows, and bursts with brighter X-ray afterglow tend
to have brighter optical afterglow. Short bursts are, on average, weaker in
both prompt and afterglow emissions. No short bursts are seen with extremely
low optical to X-ray ratio as occurs for "dark" long bursts. Although
statistics are still poor for short bursts, there is no evidence yet for a
subgroup of short bursts with high extinction as there is for long bursts. Long
bursts are detected in the dark category at the same fraction as for pre-Swift
bursts. Interesting cases are discovered of long bursts that are detected in
the optical, and yet have low enough optical to X-ray ratio to be classified as
dark. For the prompt emission, short and long bursts have different average
tracks on flux vs fluence plots. In Swift, GRB detections tend to be fluence
limited for short bursts and flux limited for long events.


title: A bracket polynomial for graphs

abstract:
  A knot diagram has an associated looped interlacement graph, obtained from
the intersection graph of the Gauss diagram by attaching loops to the vertices
that correspond to negative crossings. This construction suggests an extension
of the Kauffman bracket to an invariant of looped graphs, and an extension of
Reidemeister equivalence to an equivalence relation on looped graphs. The graph
bracket polynomial can be defined recursively using the same pivot and local
complementation operations used to define the interlace polynomial, and it
gives rise to a graph Jones polynomial that is invariant under the graph
Reidemeister moves.


title:
The Detection of Low Mass Companions in Hyades Cluster Spectroscopic
  Binary Stars

abstract:
  We have observed a large sample of spectroscopic binary stars in the Hyades
Cluster, using high resolution infrared spectroscopy to detect low mass
companions. We combine our double-lined infrared measurements with well
constrained orbital parameters from visible light single-lined observations to
derive dynamical mass ratios. Using these results, along with photometry and
theoretical mass-luminosity relationships, we estimate the masses of the
individual components in our binaries. In this paper we present double-lined
solutions for 25 binaries in our sample, with mass ratios from ~0.1-0.8. This
corresponds to secondary masses as small as ~0.15 Msun. We include here our
preliminary detection of the companion to vB 142, with a very small mass ratio
of q=0.06+-0.04; this indicates that the companion may be a brown dwarf. This
paper is an initial step in a program to produce distributions of mass ratio
and secondary mass for Hyades cluster binaries with a wide range of periods, in
order to better understand binary star formation. As such, our emphasis is on
measuring these distributions, not on measuring precise orbital parameters for
individual binaries.


title:
On a doubly nonlinear diffusion model of chemotaxis with prevention of
  overcrowding

abstract:
  This paper addresses the existence and regularity of weak solutions for a
fully parabolic model of chemotaxis, with prevention of overcrowding, that
degenerates in a two-sided fashion, including an extra nonlinearity represented
by a $p$-Laplacian diffusion term. To prove the existence of weak solutions, a
Schauder fixed-point argument is applied to a regularized problem and the
compactness method is used to pass to the limit. The local H\"older regularity
of weak solutions is established using the method of intrinsic scaling. The
results are a contribution to showing, qualitatively, to what extent the
properties of the classical Keller-Segel chemotaxis models are preserved in a
more general setting. Some numerical examples illustrate the model.


title: Numerical validation of the Complex Swift-Hohenberg equation for lasers

abstract:
  Order parameter equations, such as the complex Swift-Hohenberg (CSH)
equation, offer a simplified and universal description that hold close to an
instability threshold. The universality of the description refers to the fact
that the same kind of instability produces the same order parameter equation.
In the case of lasers, the instability usually corresponds to the emitting
threshold, and the CSH equation can be obtained from the Maxwell-Bloch (MB)
equations for a class C laser with small detuning. In this paper we numerically
check the validity of the CSH equation as an approximation of the MB equations,
taking into account that its terms are of different asymptotic order, and that,
despite of having been systematically overlooked in the literature, this fact
is essential in order to correctly capture the weakly nonlinear dynamics of the
MB. The approximate distance to threshold range for which the CSH equation
holds is also estimated.


title: Nano-Graphene Oxide for Cellular Imaging and Drug Delivery

abstract:
  Two-dimensional graphene offers interesting electronic, thermal and
mechanical properties that are currently explored for advanced electronics,
membranes and composites. Here we synthesize and explore the biological
application of nano-graphene oxide NGO, single-layer graphene oxide sheets down
to a few nanometers in lateral width. We develop functionalization chemistry to
impart solubility and compatibility of NGO in biological environments. We
obtain size separated pegylated NGO sheets that are soluble in buffers and
serum without agglomeration. The NGO sheets are found to be photoluminescent in
the visible and infrared regions. The intrinsic photoluminescence of NGO is
used for live cell imaging in the near-infrared with little background. We
found that simple physisorption via pi-stacking can be used for loading
doxorubicin, a widely used cancer drug onto NGO functionalized with antibody
for selective cancer cell killing in vitro. Owing to the small size, intrinsic
optical properties, large specific surface area,low cost, and useful
non-covalent interactions with aromatic drug molecules, NGO is a promising new
material for biological and medical applications.


title:
Weighted-Interaction Nestedness Estimator (WINE): A new estimator to
  calculate over frequency matrices

abstract:
  We have developed a graphical user interface (GUI) running in Matlab, called
Weighted-Interaction Nestedness Estimator, WINE (Fig. 1). WINE is a Matlab
application developed to perform the calculation of the new weighted nestedness
estimator. This program allows the user to: open a data file, select the range
of data to be analysed, and calculate the results, obtaining two graphics and
three indices. The indices shown in the graphical interface are: a) weighted
nestedness of the frequency matrix, b) average weighted nestedness of 100
random matrices of similar characteristics, and c) the new weighted-
interaction nestedness estimator, which compares the two previous results.


title:
Unconventional superconductivity of NdFeAsO0.82F0.18 indicated by the
  low temperature dependence of the lower critical field Hc1

abstract:
  We measured the initial M-H curves for a sample of the newly discovered
superconductor NdFeAsO0.82Fe0.18, which had a critical temperature, Tc, of 51
K, and was fabricated at the high pressure of 6 GPa. The lower critical field,
Hc1, was extracted from the deviation point of the Meissner linearity in the
M-H curves, which show linear temperature dependence in the low temperature
region down to 5 K. The Hc1(T) indicates no s-wave superconductivity, but
rather an unconventional superconductivity with a nodal gap structure.
Furthermore, the linearity of Hc1 at low temperature does not hold at high
temperature, but shows other characteristics, indicating that this
superconductor might have multi-gap features. Based on the low temperature
nodal gap structure, we estimate that the maximum gap magnitude delta 0 =
(1.6+- 0.2) kBTc.


title:
LRSA: A new computational method for analyzing time course microarray
  data

abstract:
  Motivation: Time course data obtained from biological samples subject to
specific treatments can be very useful for revealing complex and novel
biological phenomena. Although an increasing number of time course microarray
datasets becomes available, most of them contain few biological replicates and
time points. So far there are few computational methods that can effectively
reveal differentially expressed genes and their patterns in such data.
  Results: We have proposed a new two-step nonparametric statistical procedure,
LRSA, to reveal differentially expressed genes and their expression trends in
temporal microarray data. We have also employed external controls as a
surrogate to estimate false discovery rates and thus to guide the discovery of
differentially expressed genes. Our results showed that LRSA reveals
substantially more differentially expressed genes and have much lower than two
other methods, STEM and ANOVA, in both real data and the simulated data. Our
computational results are confirmed using real-time PCRs.
  Contact: wuw2@upmc.edu


title: Comprehensive Two-Point Analyses of Weak Gravitational Lensing Surveys

abstract:
  We present a framework for analyzing weak gravitational lensing survey data,
including lensing and source-density observables, plus spectroscopic redshift
calibration data. All two-point observables are predicted in terms of
parameters of a perturbed Robertson-Walker metric, making the framework
independent of the models for gravity, dark energy, or galaxy properties. For
Gaussian fluctuations the 2-point model determines the survey likelihood
function and allows Fisher-matrix forecasting. The framework includes nuisance
terms for the major systematic errors: shear measurement errors, magnification
bias and redshift calibration errors, intrinsic galaxy alignments, and
inaccurate theoretical predictions. We propose flexible parameterizations of
the many nuisance parameters related to galaxy bias and intrinsic alignment.
For the first time we can integrate many different observables and systematic
errors into a single analysis. As a first application of this framework, we
demonstrate that: uncertainties in power-spectrum theory cause very minor
degradation to cosmological information content; nearly all useful information
(excepting baryon oscillations) is extracted with ~3 bins per decade of angular
scale; and the rate at which galaxy bias varies with redshift substantially
influences the strength of cosmological inference. The framework will permit
careful study of the interplay between numerous observables, systematic errors,
and spectroscopic calibration data for large weak-lensing surveys.


title: Substructures in hydrodynamical cluster simulations

abstract:
  The abundance and structure of dark matter subhalos has been analyzed
extensively in recent studies of dark matter-only simulations, but
comparatively little is known about the impact of baryonic physics on halo
substructures. We here extend the SUBFIND algorithm for substructure
identification such that it can be reliably applied to dissipative
hydrodynamical simulations that include star formation. This allows, in
particular, the identification of galaxies as substructures in simulations of
clusters of galaxies, and a determination of their content of gravitationally
bound stars, dark matter, and hot and cold gas. Using a large set of
cosmological cluster simulations, we present a detailed analysis of halo
substructures in hydrodynamical simulations of galaxy clusters, focusing in
particular on the influence both of radiative and non-radiative gas physics,
and of non-standard physics such as thermal conduction and feedback by galactic
outflows. We also examine the impact of numerical nuisance parameters such as
artificial viscosity parameterizations. We find that diffuse hot gas is
efficiently stripped from subhalos when they enter the highly pressurized
cluster atmosphere. This has the effect of decreasing the subhalo mass function
relative to a corresponding dark matter-only simulation. These effects are
mitigated in radiative runs, where baryons condense in the central subhalo
regions and form compact stellar cores. However, in all cases, only a very
small fraction, of the order of one percent, of subhalos within the cluster
virial radii preserve a gravitationally bound hot gaseous atmosphere.
(abridged)


title: Call option prices based on Bessel processes

abstract:
  As a complement to some recent work by Pal and Protter, "Strict local
martingales, bubbles, and no early exercise", we show that the call option
prices associated with the Bessel strict local martingales are integrable over
time, and we discuss the probability densities obtained thus.


title: Reexamination of decoherence in quantum walks on the hypercube

abstract:
  The effect of decoherence on the continuous-time quantum walk on the
hypercube is revisited. Previously, an exact solution was found for a
decoherence model that preserved the effective tensor-product form of the
dynamics. Here a new model is presented, inspired by perfect quantum state
transfer in qubit networks. A perturbative solution is found for the dynamics
of this model which is not of a tensor-product form. In contrast to previous
results, the hitting probability has a lower bound that is independent of the
hypercube dimension.


title:
Linearized Turbulent Fluid Flow as an Analog Model for Linearized
  General Relativity (Gravitoelectromagnetism)

abstract:
  In the spirit of analog models of and for general relativity, we explore the
isomorphism between the equations of linearized turbulent fluid flow and those
of the linearized form of GR, gravitoelectromagnetism. The correspondence
between the truncated Reynolds system for turbulent fluid flow and the
Maxwell-like gravitoelectromagnetic equations for weak-field GR is shown to
provide yet another example of the relationship between the representation of
fluctuations in background media and curved spacetime formulations.


title: The SL(2)-type and Base Change

abstract:
  The SL(2)-type of any smooth, irreducible and unitarizable representation of
GL(n) over a p-adic field was defined by Venkatesh. We provide a natural way to
extend the definition to all smooth and irreducible representations. For
unitarizable representations we show that the SL(2)-type of a representation is
preserved under base change with respect to any finite extension. The Klyachko
model of a smooth, irreducible and unitarizable representation \pi of GL(n)
depends only on the SL(2)-type of \pi. As a consequence we observe that the
Klyachko model of \pi and of its base-change are of the same type.


title: Higher Poisson Brackets and Differential Forms

abstract:
  We show how the relation between Poisson brackets and symplectic forms can be
extended to the case of inhomogeneous multivector fields and inhomogeneous
differential forms (or pseudodifferential forms). In particular we arrive at a
notion which is a generalization of a symplectic structure and gives rise to
higher Poisson brackets. We also obtain a construction of Koszul type brackets
in this setting.


title:
The close environment of 24 micron galaxies at 0.6<z<1.0 in the COSMOS
  field

abstract:
  We investigate the close environment of 203 Spitzer 24 micron-selected
sources at 0.6<z<1.0 using zCOSMOS-bright redshifts and spectra of I<22.5 AB
mag galaxies, over 1.5 sq. deg. of the COSMOS field. We quantify the degree of
passivity of the LIRG and ULIRG environments by analysing the fraction of close
neighbours with Dn(4000)>1.4. We find that LIRGs at 0.6<z<0.8 live in more
passive environments than those of other optical galaxies that have the same
stellar mass distribution. Instead, ULIRGs inhabit more active regions (e.g.
LIRGs and ULIRGs at 0.6<z<0.8 have, respectively, (42.0 +/- 4.9)% and (24.5 +/-
5.9)% of neighbours with Dn (4000)>1.4 within 1 Mpc and +/- 500 km/s). The
contrast between the activities of the close environments of LIRGs and ULIRGs
appears especially enhanced in the COSMOS field density peak at z~0.67, because
LIRGs on this peak have a larger fraction of passive neighbours, while ULIRGs
have as active close environments as those outside the large-scale structure.
The differential environmental activity is related to the differences in the
distributions of stellar mass ratios between LIRGs/ULIRGs and their close
neighbours, as well as in the general local density fields. At 0.8<z<1.0,
instead, we find no differences in the environment densities of ULIRGs and
other similarly massive galaxies, in spite of the differential activities. We
discuss a possible scenario to explain these findings.


title:
Near-isotropic performance of intrinsically anisotropic high-temperature
  superconducting tapes due to self-assembled nanostructures

abstract:
  High-temperature superconductors (HTS) are finding use as high - current
wires for potential application in power devices. The dependence of their
basal-plane critical current properties on orientation in a magnetic field can
pose important design problems. Here we report material and operating parameter
conditions where prototype HTS tape conductors exhibit critical current
characteristics that are essentially field-orientation independent. The novel
phenomenon is observed for specific magnetic field intensities that depend on
the operating temperature, and in materials having strong flux pinning by
extended nanoscale structures aligned roughly along the HTS crystalline c-axis.
The effect can be described by a simple model for the field dependence of
critical current density, generalized for anisotropic electronic response. This
description may provide insight into means to fine-tune the material properties
for nearly isotropic performance characteristics at a preferred field and
temperature.


title:
Stability and normal zone propagation speed in YBCO coated conductors
  with increased interfacial resistance

abstract:
  We will discuss how stability and speed of normal zone propagation in
YBCO-coated conductors is affected by interfacial resistance between the
superconducting film and the stabilizer. Our numerical simulation has shown
that the increased interfacial resistance substantially increases speed of
normal zone propagation and decreases the stability margins. Optimization of
the value of the resistance may lead to a better compromise between stability
and quench protection requirements than what is found in currently manufactured
coated conductors.


title:
Interacting String Multi-verses and Holographic Instabilities of Massive
  Gravity

abstract:
  Products of large-N conformal field theories coupled by multi-trace
interactions in diverse dimensions are used to define quantum multi-gravity
(multi-string theory) on a union of (asymptotically) AdS spaces. One-loop
effects generate a small O(1/N) mass for some of the gravitons. The boundary
gauge theory and the AdS/CFT correspondence are used as guiding principles to
study and draw conclusions on some of the well known problems of massive
gravity - classical instabilities and strong coupling effects. We find examples
of stable multi-graviton theories where the usual strong coupling effects of
the scalar mode of the graviton are suppressed. Our examples require a fine
tuning of the boundary conditions in AdS. Without it, the spacetime background
backreacts in order to erase the effects of the graviton mass.


title:
Objects In Telescope Are Farther Than They Appear: How diffraction
  tricked Galileo into mismeasuring the distances to the stars

abstract:
  Galileo determined distances to stars based on the assumption that stars were
suns, the apparent sizes of stars as seen through his telescope, and basic
geometry. However, the apparent sizes that he measured were the result of
diffraction and not related to the actual sizes of the stars. Galileo's methods
and observations were good, but since he was unknowingly observing diffraction
artifacts and not the physical bodies of stars he greatly underestimated the
distances to the stars.


title:
Complete Constant Mean Curvature surfaces and Bernstein type Theorems in
  $\mathbb{M}^2\times \mathbb{R}$

abstract:
  In this paper we study constant mean curvature surfaces $\Sigma$ in a product
space, $\mathbb{M}^2\times \mathbb{R}$, where $\mathbb{M}^2$ is a complete
Riemannian manifold. We assume the angle function $\nu = \meta{N}{\partial_t}$
does not change sign on $\Sigma$. We classify these surfaces according to the
infimum $c(\Sigma)$ of the Gaussian curvature of the projection of $\Sigma$.
  When $H \neq 0$ and $c(\Sigma)\geq 0$, then $\Sigma $ is a cylinder over a
complete curve with curvature 2H. If H=0 and $c(\Sigma) \geq 0$, then $\Sigma$
must be a vertical plane or $\Sigma$ is a slice $\mathbb{M}^2 \times {t}$, or
$\mathbb{M}^2 \equiv \mathbb{R}^2$ with the flat metric and $\Sigma$ is a
tilted plane (after possibly passing to a covering space).
  When $c(\Sigma)<0$ and $H>\sqrt{-c(\Sigma)} /2$, then $\Sigma$ is a vertical
cylinder over a complete curve of $\mathbb{M}^2$ of constant geodesic curvature
$2H$. This result is optimal.
  We also prove a non-existence result concerning complete multi-graphs in
$\mathbb{M}^2\times \mathbb{R}$, when $c(\mathbb{M}^2)<0$.


title:
Comments on anomaly versus WKB/tunneling methods for calculating Unruh
  radiation

abstract:
  In this Letter we make a critique of, and comparison between, the anomaly
method and WKB/tunneling method for obtaining radiation from non-trivial
spacetime backgrounds. We focus on Rindler spacetime (the spacetime of an
accelerating observer) and the associated Unruh radiation since this is the
prototype of the phenomena of radiation from a spacetime, and it is the
simplest model for making clear subtle points in the tunneling and anomaly
methods. Our analysis leads to the following conclusions: (i) neither the
consistent and covariant anomaly methods gives the correct Unruh temperature
for Rindler spacetime and in some cases (e.g. de Sitter spacetime) the
consistent and covariant methods disagree with one another; (ii) the tunneling
method can be applied in all cases, but it has a previously unnoticed temporal
contribution which must be accounted for in order to obtain the correct
temperature.


title: Common Proper Motion Companions to Nearby Stars: Ages and Evolution

abstract:
  A set of 41 nearby stars (closer than 25 pc) is investigated which have very
wide binary and common proper motion (CPM) companions at projected separations
between 1000 and $200 000$ AU. These companions are identified by astrometric
positions and proper motions from the NOMAD catalog. Based mainly on measures
of chromospheric and X-ray activity, age estimation is obtained for most of 85
identified companions. Color -- absolute magnitude diagrams are constructed to
test if CPM companions are physically related to the primary nearby stars and
have the same age. Our carefully selected sample includes three remote white
dwarf companions to main sequence stars and two systems (55 Cnc and GJ 777A) of
multiple planets and distant stellar companions. Ten new CPM companions,
including three of extreme separations, are found. Multiple hierarchical
systems are abundant; more than 25% of CPM components are spectroscopic or
astrometric binaries or multiples themselves. Two new astrometric binaries are
discovered among nearby CPM companions, GJ 264 and HIP 59000 and preliminary
orbital solutions are presented. The Hyades kinematic group (or stream) is
presented broadly in the sample, but we find few possible thick disk objects
and none halo stars. It follows from our investigation that moderately young
(age $\lesssim 1$ Gyr) thin disk dwarfs are the dominating species in the near
CPM systems, in general agreement with the premises of the dynamical survival
paradigm. Some of the multiple stellar systems with remote CPM companions
probably undergo the dynamical evolution on non-coplanar orbits, known as the
Kozai cycle.


title: On the Cayley semigroup of a finite aperiodic semigroup

abstract:
  Let $S$ be a finite semigroup. In this paper we introduce the functions
$\phi_s:S^* \to S^*$, first defined by Rhodes, given by $\phi_s([a_1,a_2
,...,a_n]) = [sa_1,sa_1a_2,..., sa_1a_2 ... a_n]$. We show that if $S$ is a
finite aperiodic semigroup, then the semigroup generated by the functions
$\{\phi_s\}_{s \in S}$ is finite and aperiodic.


title: Uncertainty quantification in complex systems using approximate solvers

abstract:
  This paper proposes a novel uncertainty quantification framework for
computationally demanding systems characterized by a large vector of
non-Gaussian uncertainties. It combines state-of-the-art techniques in advanced
Monte Carlo sampling with Bayesian formulations. The key departure from
existing works is the use of inexpensive, approximate computational models in a
rigorous manner. Such models can readily be derived by coarsening the
discretization size in the solution of the governing PDEs, increasing the time
step when integration of ODEs is performed, using fewer iterations if a
non-linear solver is employed or making use of lower order models. It is shown
that even in cases where the inexact models provide very poor approximations of
the exact response, statistics of the latter can be quantified accurately with
significant reductions in the computational effort. Multiple approximate models
can be used and rigorous confidence bounds of the estimates produced are
provided at all stages.


title:
Self-healing diffusion quantum Monte Carlo algorithms: methods for
  direct reduction of the fermion sign error in electronic structure
  calculations

abstract:
  We develop a formalism and present an algorithm for optimization of the trial
wave-function used in fixed-node diffusion quantum Monte Carlo (DMC) methods.
We take advantage of a basic property of the walker configuration distribution
generated in a DMC calculation, to (i) project-out a multi-determinant
expansion of the fixed-node ground-state wave function and (ii) to define a
cost function that relates the fixed-node ground-state and the non-interacting
trial wave functions. We show that (a) locally smoothing out the kink of the
fixed-node ground-state wave function at the node generates a new trial
wave-function with better nodal structure and (b) we argue that the noise in
the fixed-node wave-function resulting from finite sampling plays a beneficial
role, allowing the nodes to adjust towards the ones of the exact many-body
ground state in a simulated annealing-like process. We propose a method to
improve both single determinant and multi-determinant expansions of the trial
wave-function. We test the method in a model system where benchmark
configuration interaction calculations can be performed. Comparing the DMC
calculations with the exact solutions, we find that the trial wave-function is
systematically improved. The overlap of the optimized trial wave function and
the exact ground state converges to 100% even starting from wave-functions
orthogonal to the exact ground state. In the optimization process we find an
optimal non-interacting nodal potential of density-functional-like form whose
existence was predicted earlier[Phys.Rev. B {\bf 77}, 245110 (2008)]. We obtain
the exact Kohn-Sham effective potential from the DMC data.


title:
Jamming in Fixed-Rate Wireless Systems with Power Constraints - Part II:
  Parallel Slow Fading Channels

abstract:
  This is the second part of a two-part paper that studies the problem of
jamming in a fixed-rate transmission system with fading. In the first part, we
studied the scenario with a fast fading channel, and found Nash equilibria of
mixed strategies for short term power constraints, and for average power
constraints with and without channel state information (CSI) feedback. We also
solved the equally important maximin and minimax problems with pure strategies.
Whenever we dealt with average power constraints, we decomposed the problem
into two levels of power control, which we solved individually. In this second
part of the paper, we study the scenario with a parallel, slow fading channel,
which usually models multi-carrier transmissions, such as OFDM. Although the
framework is similar as the one in Part I \cite{myself3}, dealing with the slow
fading requires more intricate techniques. Unlike in the fast fading scenario,
where the frames supporting the transmission of the codewords were equivalent
and completely characterized by the channel statistics, in our present scenario
the frames are unique, and characterized by a specific set of channel
realizations. This leads to more involved inter-frame power allocation
strategies, and in some cases even to the need for a third level of power
control. We also show that for parallel slow fading channels, the CSI feedback
helps in the battle against jamming, as evidenced by the significant
degradation to system performance when CSI is not sent back. We expect this
degradation to decrease as the number of parallel channels $M$ increases, until
it becomes marginal for $M\to \infty$ (which can be considered as the case in
Part I).


title: Probing Dark Energy with Black Hole Binaries

abstract:
  The equation of state (EoS) of dark energy $w$ remains elusive despite
enormous experimental efforts to pin down its value and its time variation. Yet
it is the single most important handle we have in our understanding of one of
the most mysterious puzzle in nature, dark energy. This letter proposes a new
method for measuring the EoS of dark energy by using the gravitational waves
(GW) of black hole binaries. The method described here offers an alternative to
the standard way of large scale surveys.
  It is well known that the mass of a black hole changes due to the accretion
of dark energy but at an extremely slow rate. However, a binary of supermassive
black holes (SBH) radiates gravitational waves with a power proportional to the
masses of these accreting stars and thereby carries information on dark energy.
These waves can propagate through the vastness of structure in the universe
unimpeded. The orbital changes of the binary, induced by the energy loss from
gravitational radiation, receive a large contribution from dark energy
accretion. This contribution is directly proportional to $(1+w)$ and is
dominant for SBH binaries with separation $R \ge 1000$ parsec, thereby
accelerating the merging process for $w > -1$ or ripping the stars apart for
phantom dark energy with $w < -1$. Such orbital changes, therefore $w$, can be
detected with LIGO and LISA near merging time, or with X-ray and radio
measurements of Chandra and VLBA experiments.


title: Ab initio no-core full configuration calculations of light nuclei

abstract:
  We perform no-core full configuration calculations for a set of light nuclei
including $^{16}$O with a realistic NN interaction, JISP16. We obtain ground
state energies and their uncertainties through exponential extrapolations that
we demonstrate are reliable in $^2$H, $^3$H and $^4$He test cases where fully
converged results are obtained directly. We find that $^6$He, $^6$Li and $^8$He
are underbound by about 600 keV, 560 keV and 1.7 MeV, respectively. $^{12}$C is
overbound by about 1.7 MeV and $^{16}$O is overbound by about 16 MeV. The first
excited $0^+$ states in $^{12}$C and $^{16}$O are also evaluated but their
uncertainties are significantly larger than the uncertainties for the ground
states.


title: A New Invariant Metric and Applications

abstract:
  We construct a new invariant metric for a compact subgroup of the
automorphism group of a domain in complex space. Applications are provided.


title: Dynamics of barred galaxies: effects of disk height

abstract:
  We study dynamics of bars in models of disk galaxies embeded in realistic
dark matter halos. We find that disk thickness plays an important, if not
dominant, role in the evolution and structure of the bars. We also make
extensive numerical tests of different N-body codes used to study bar dynamics.
Models with thick disks typically used in this type of modeling
(height-to-length ratio hz/Rd=0.2) produce slowly rotating, and very long,
bars. In contrast, more realistic thin disks with the same parameters as in our
Galaxy (hz/Rd= 0.1) produce bars with normal length Rbar approx R_d, which
rotate quickly with the ratio of the corotation radius to the bar radius
1.2-1.4 compatible with observations. Bars in these models do not show a
tendency to slow down, and may lose as little as 2-3 percent of their angular
momentum due to dynamical friction with the dark matter over cosmological time.
We attribute the differences between the models to a combined effect of high
phase-space density and smaller Jeans mass in the thin disk models, which
result in the formation of a dense central bulge. Special attention is paid to
numerical effects such as the accuracy of orbital integration, force and mass
resolution. Using three N-body codes -- Gadget, ART, and Pkdgrav -- we find
that numerical effects are very important and, if not carefully treated, may
produce incorrect and misleading results. Once the simulations are performed
with sufficiently small time-steps and with adequate force and mass resolution,
all the codes produce nearly the same results: we do not find any systematic
deviations between the results obtained with TREE codes (Gadget and Pkdgrav)
and with the Adaptive-Mesh-Refinement (ART) code.


title:
Nonlinear magnetoresistance of an irradiated two-dimensional electron
  system

abstract:
  Nonlinear magnetotransport of a microwave-irradiated high mobility
two-dimensional electron system under a finite direct current excitation is
analyzed using a dc-controlled scheme with photon-assisted transition
mechanism. The predicted amplitudes, extrema and nodes of the oscillatory
differential resistance versus the magnetic field and the current density, are
in excellent agreement with the recent experimental observation [Hatke et al.
Phys. Rev. B 77, 201304(R) (2008)].


title:
The Range of a Class of Classifiable Separable Simple Amenable
  C*-Algebras

abstract:
  We study the range of a classifiable class ${\cal A}$ of unital separable
simple amenable $C^*$-algebras which satisfy the Universal Coefficient Theorem.
The class ${\cal A}$ contains all unital simple AH-algebras. We show that all
unital simple inductive limits of dimension drop circle $C^*$-algebras are also
in the class. This unifies some of the previous known classification results
for unital simple amenable $C^*$-algebras. We also show that there are many
other $C^*$-algebras in the class. We prove that, for any partially ordered,
simple weakly unperforated rationally Riesz group $G_0$ with order unit $u,$
any countable abelian group $G_1,$ any metrizable Choquet simplex $S,$ and any
surjective affine continuous map $r: S\to S_u(G_0)$ (where $S_u(G_0)$ is the
state space of $G_0$) which preserves extremal points, there exists one and
only one (up to isomorphism) unital separable simple amenable $C^*$-algebra $A$
in the classifiable class ${\cal A}$ such that $$ ((K_0(A), K_0(A)_+, [1_A]),
K_1(A), T(A), \lambda_A)=((G_0, (G_0)_+, u), G_1,S, r).


title: LSST and the Dark Sector: Image Processing Challenges

abstract:
  Next generation probes of dark matter and dark energy require high precision
reconstruction of faint galaxy shapes from hundreds of dithered exposures.
Current practice is to stack the images. While valuable for many applications,
this stack is a highly compressed version of the data. Future weak lensing
studies will require analysis of the full dataset using the stack and its
associated catalog only as a starting point. We describe a "Multi-Fit"
algorithm which simultaneously fits individual galaxy exposures to a common
profile model convolved with each exposure's point spread function at that
position in the image. This technique leads to an enhancement of the number of
usable small galaxies at high redshift and, more significantly, a decrease in
systematic shear error.


title:
The base change fundamental lemma for central elements in parahoric
  Hecke algebras

abstract:
  Clozel and Labesse proved the base change fundamental lemma for spherical
Hecke algebras attached to an unramified group over a p-adic field. This paper
proves an analogous fundamental lemma for centers of parahoric Hecke algebras
attached to the same class of groups. This provides an ingredient needed for
the author's program to study Shimura varieties with parahoric level structure
at p.


title:
Improvement and protection of niobium surface superconductivity by
  Atomic Layer Deposition and heat treatment

abstract:
  A method to treat the surface of Nb is described which potentially can
improve the performance of superconducting RF cavities. We present tunneling
and x-ray photoemission spectroscopy (XPS) measurements at the surface of
cavity-grade niobium samples coated with a 3 nm alumina overlayer deposited by
Atomic Layer Deposition (ALD). The coated samples baked in ultra high vacuum
(UHV) at low temperature reveal at first degraded superconducting surface.
However, at temperatures above 450C, the tunneling conductance curves show
significant improvements of the superconducting density of states (DOS)
compared with untreated surfaces.


title: Vanishing viscosity in the plane for nondecaying velocity and vorticity

abstract:
  Assuming that initial velocity and initial vorticity are bounded in the
plane, we show that on a sufficiently short time interval the unique solutions
of the Navier-Stokes equations converge uniformly to the unique solution of the
Euler equations as viscosity approaches zero. We also establish a rate of
convergence.


title:
Ghost-Free Higher Derivative Quantum Gravity, the Hierarchy and the
  Cosmological Constant Problems

abstract:
  Proposing new solution problems of the hierarchy and smallness of the
cosmological constant using the Tev scale of the Standard Model in new
framework of the higher-order gravity.


title:
Ward-Takahashi identity for Yang-Mills theory in the Exact
  Renormalization Group

abstract:
  We give a functional derivation of the Ward-Takahashi identity for Yang-Mills
theory in the framework of the exact renormalization group. The identity
realizes non-abelian gauge symmetry nontrivially despite the presence of a
momentum cutoff. The cutoff deforms the gauge transformation by introducing
composite operators. In our functional method, which is an extension of the
method used in our previous work on QED, these composite operators are
expressed in terms of the Wilson action that depends on both a UV cutoff and an
IR cutoff.


title:
Jamming in Fixed-Rate Wireless Systems with Power Constraints - Part I:
  Fast Fading Channels

abstract:
  This is the first part of a two-part paper that studies the problem of
jamming in a fixed-rate transmission system with fading. Both transmitter and
jammer are subject to power constraints which can be enforced over each
codeword short-term / peak) or over all codewords (long-term / average), hence
generating different scenarios. All our jamming problems are formulated as
zero-sum games, having the probability of outage as pay-off function and power
control functions as strategies. The paper aims at providing a comprehensive
coverage of these problems, under fast and slow fading, peak and average power
constraints, pure and mixed strategies, with and without channel state
information (CSI) feedback. In this first part we study the fast fading
scenario. We first assume full CSI to be available to all parties. For peak
power constraints, a Nash equilibrium of pure strategies is found. For average
power constraints, both pure and mixed strategies are investigated. With pure
strategies, we derive the optimal power control functions for both intra-frame
and inter-frame power allocation. Maximin and minimax solutions are found and
shown to be different, which implies the non-existence of a saddle point. In
addition we provide alternative perspectives in obtaining the optimal
intra-frame power control functions under the long-term power constraints. With
mixed strategies, the Nash equilibrium is found by solving the generalized form
of an older problem dating back to Bell and Cover \cite{bell}. Finally, we
derive a Nash equilibrium of the game in which no CSI is fed back from the
receiver. We show that full channel state information brings only a very slight
improvement in the system's performance.


title:
Comment on "Discrepancies in the resonance-fluorescence spectrum
  calculated with two methods"

abstract:
  There are two alternative methods used in literature to calculate the
incoherent part of the spectrum of light scattered by an atomic system. In the
first, one calculates the spectrum of the total light scattered by the system
and obtains the incoherent part by subtracting the coherent part. In the second
method, one introduces the fluctuation operators and obtains the incoherent
part of the spectrum by taking the Fourier transform of the two time
correlation function of the fluctuation operators. These two methods have been
recognized for years as two completely equivalent for evaluating the incoherent
part of the spectrum. In a recent paper Qing Xu et al. [Phys. Rev. A 78, 013407
(2008)] have shown that there are discrepancies between the incoherent parts of
the stationary spectrum of a three-level Lambda-type system calculated with
these two methods. The predicted discrepancies can be severe that over a wide
rage of the Rabi frequencies and atomic decay rates, the spectrum calculated
with the variance method can have negative values. This is obviously unphysical
result since the fluorescence spectrum is a positively defined quantity. It
represents the frequency distribution of light incoherently scattered by the
atomic system. Therefore, the calculated spectrum should be positive for all
frequencies independent of values of the Rabi frequencies and the damping
rates. In this comment, we show that there are no discrepancies between these
two methods. The equivalence of these two alternative methods leads to the same
incoherent spectra that are positive for all frequencies independent of values
of the parameters involved. The analytical analysis is supported by simple
numerical calculations.


title: How many species have mass M?

abstract:
  Within large taxonomic assemblages, the number of species with adult body
mass M is characterized by a broad but asymmetric distribution, with the
largest mass being orders of magnitude larger than the typical mass. This
canonical shape can be explained by cladogenetic diffusion that is bounded
below by a hard limit on viable species mass and above by extinction risks that
increase weakly with mass. Here we introduce and analytically solve a
simplified cladogenetic diffusion model. When appropriately parameterized, the
diffusion-reaction equation predicts mass distributions that are in good
agreement with data on 4002 terrestrial mammal from the late Quaternary and
8617 extant bird species. Under this model, we show that a specific tradeoff
between the strength of within-lineage drift toward larger masses (Cope's rule)
and the increased risk of extinction from increased mass is necessary to
produce realistic mass distributions for both taxa. We then make several
predictions about the evolution of avian species masses.


title: Two-photon photoassociative spectroscopy of ultracold 88-Sr

abstract:
  We present results from two-photon photoassociative spectroscopy of the
least-bound vibrational level of the X$^1\Sigma_g^+$ state of the $^{88}$Sr$_2$
dimer. Measurement of the binding energy allows us to determine the s-wave
scattering length, $a_{88}=-1.4(6) a_0$. For the intermediate state, we use a
bound level on the metastable $^1S_0$-$^3P_1$ potential, which provides large
Franck-Condon transition factors and narrow one-photon photoassociative lines
that are advantageous for observing quantum-optical effects such as
Autler-Townes resonance splittings.


title:
Symmetry operators and separability of massive Klein-Gordon and Dirac
  equations in the general 5-dimensional Kerr-(anti-)de Sitter black hole
  background

abstract:
  It is shown that the Dirac equation is separable by variables in a
five-dimensional rotating Kerr-(anti-)de Sitter black hole with two independent
angular momenta. A first order symmetry operator that commutes with the Dirac
operator is constructed in terms of a rank-three Killing-Yano tensor whose
square is a second order symmetric Stackel-Killing tensor admitted by the
five-dimensional Kerr-(anti-)de Sitter spacetime. We highlight the construction
procedure of such a symmetry operator. In addition, the first law of black hole
thermodynamics has been extended to the case that the cosmological constant can
be viewed as a thermodynamical variable.

categories: hep-th astro-ph.HE gr-qc hep-ph math-ph math.MP quant-ph


title:
Suzaku Observation of HESS J1825-137: Discovery of Largely-Extended
  X-rays near from PSR J1826-1334

abstract:
  We observed the brightest part of HESS J1825-137 with the Suzaku XIS, and
found diffuse X-rays extending at least up to 15' (~ 17 pc) from the pulsar PSR
J1826-1334. The spectra have no emission line, and are fitted with an absorbed
power-law model. The X-rays, therefore, are likely due to synchrotron emission
from a pulsar wind nebula. The photon index near at the pulsar (r<1.5') is 1.7
while those in r=1.5-16 are nearly constant at Gamma=2.0. The spectral energy
distribution of the Suzaku and H.E.S.S. results are naturally explained by a
combined process; synchrotron X-rays and gamma-rays by the inverse Compton of
the cosmic microwave photons by high-energy electrons in a magnetic field of 7
micro G. If the electrons are accelerated at the pulsar, the electrons must be
transported over 17 pc in the synchrotron life time of 1900 yr, with a velocity
of > 8.8 times 10^3 km s^{-1}.


title: Dissipative solitons stabilized by a quantum Zeno-like effect

abstract:
  An unstable particle in quantum mechanics can be stabilized by frequent
measurements, known as the quantum Zeno effect. A soliton with dissipation
behaves like an unstable particle. Similar to the quantum Zeno effect, here we
show that the soliton can be stabilized by modulating periodically dispersion,
nonlinearity, or the external harmonic potential available in BEC. This can be
obtained by analyzing a Painleve integrability condition, which results from
the rigorous Painleve analysis of the generalized nonautonomous nonlinear
Schrodinger equation. The result has a profound implication to the optical
soliton transmission and the matter-wave soliton dynamics.


title:
A mathematical proof that the transition to a superconducting state is a
  second-order phase transition

abstract:
  We deal with the gap function and the thermodynamical potential in the
BCS-Bogoliubov theory of superconductivity, where the gap function is a
function of the temperature $T$ only. We show that the squared gap function is
of class $C^2$ on the closed interval $[ 0, T_c ]$ and point out some more
properties of the gap function. Here, $T_c$ stands for the transition
temperature. On the basis of this study we then give, examining the
thermodynamical potential, a mathematical proof that the transition to a
superconducting state is a second-order phase transition. Furthermore, we
obtain a new and more precise form of the gap in the specific heat at constant
volume from a mathematical point of view.


title:
Combinatorial bases for multilinear parts of free algebras with double
  compatible brackets

abstract:
  Let X be an ordered alphabet. Lie_2(n) (and P_2(n) respectively) are the
multilinear parts of the free Lie algebra (and the free Poisson algebra
respectively) on X with a pair of compatible Lie brackets. In this paper, we
prove the dimension formulas for these two algebras conjectured by B. Feigin by
constructing bases for Lie_2(n) (and P_2(n)) from combinatorial objects. We
also define a complementary space Eil_2(n) to Lie_2(n), give a pairing between
Lie_2(n) and Eil_2(n), and show that the pairing is perfect.


title:
The Hall conductance, topological quantum phase transition and the
  Diophantine equation on honeycomb lattice

abstract:
  We consider a tight-binding model with the nearest neighbour hopping
integrals on the honeycomb lattice in a magnetic field. Assuming one of the
three hopping integrals, which we denote t_a, can take a different value from
the two others, we study quantum phase structures controlled by the anisotropy
of the honeycomb lattice.For weak and strong t_a regions, respectively, the
Hall conductances are calculated algebraically by using the Diophantine
equation. Except for a few specific gaps, we completely determine the Hall
conductances in these two regions including those for subband gaps. In a weak
magnetic field, it is found that the weak t_a region shows the unconventional
quantization of the Hall conductance, \sigma_{xy}=-(e^2/h)(2n+1), (n=0,\pm
1,\pm 2,...), near the half-filling, while the strong t_a region shows only the
conventional one, \sigma_{xy}=-(e^2/h)n,(n=0,1,2,...). From topological nature
of the Hall conductance, the existence of gap closing points and quantum phase
transitions in the intermediate t_a region are concluded. We also study
numerically the quantum phase structure in detail, and find that even when
t_a=1, namely in graphene case, the system is in the weak t_a phase except when
the Fermi energy is located near the van Hove singularity or the lower and
upper edges of the spectrum.


title:
The latent potential of YouTube - Will it become the 21st Century
  lecturer's film archive?

abstract:
  YouTube (http://www.youtube.com) is an online, public-access video-sharing
site that allows users to post short streaming-video submissions for open
viewing. Along with Google, MySpace, Facebook, etc. it is one of the great
success stories of the Internet, and is widely used by many of today's
undergraduate students. The higher education sector has recently realised the
potential of YouTube for presenting teaching resources/material to students,
and publicising research. This article considers another potential use for
online video archiving websites such as YouTube and GoogleVideo in higher
education - as an online video archive providing thousands of hours of video
footage for use in lectures. In this article I will discuss why this might be
useful, present some examples that demonstrate the potential for YouTube as a
teaching resource, and highlight some of the copyright and legal issues that
currently impact on the effective use of new online video websites, such as
YouTube, for use as a teaching resource.


title:
Generalizing the Tomboulis-Yaffe Inequality to SU(N) Lattice Gauge
  Theories and General Classical Spin Systems

abstract:
  We extend the inequality of Tomboulis and Yaffe in SU(2) lattice gauge theory
(LGT) to SU(N) LGT and to general classical spin systems, by use of reflection
positivity. Basically the inequalities guarantee that a system in a box that is
sufficiently insensitive to boundary conditions has a non-zero mass gap. We
explicitly illustrate the theorem in some solvable models. Strong coupling
expansion is then utilized to discuss some aspects of the theorem. Finally a
conjecture for exact expression to the off-axis mass gap of the triangular
Ising model is presented. The validity of the conjecture is tested in multiple
ways.

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


title:
High-Resolution Observations of Molecular Lines toward the Hot Core
  G28.20-0.04N

abstract:
  We present the results from arcsecond resolution observations of various line
transitions at 1.3 mm toward hypercompact HII region G28.20-0.04N. With the SMA
data, we have detected and mapped the transitions in the CH$_{3}$CN, CO,
$^{13}$CO, SO$_{2}$, OCS, and CH$_{3}$OH molecular lines as well as the radio
recombination line H30$\alpha$. The observations and analysis indicate a hot
core associated with G28.20-0.04N. The outflow and possible rotation are
detected in this region.


title: Massive Yang-Mills Fields in Interaction with Gravity

abstract:
  We determine the most general form of the interaction between the
gravitational field and an arbitrary Yang-Mills system of fields (massless and
massive). We work in the perturbative quantum framework of the causal approach
(of Epstein and Glaser) and use a cohomological definition of gauge invariance
for both gauge fields. We also consider the case of massive gravity. We discuss
the question whether gravity couples to the unphysical degrees of freedom in
the Yang-Mills fields.


title:
Displacement-noise-free resonant speed meter for gravitational-wave
  detection

abstract:
  We demonstrate that speedmeter, based on double pumped resonant Sagnac
interferometer, can be used as a displacement noise free gravitational-wave
(GW) detector. The displacement noise of cavity mirrors can be completely
excluded through a proper linear combination of the output signals. We show
that in low-frequency region the obtained displacement-noise-free response
signal is stronger than the one in previously proposed displacement noise free
interferometers.


title:
Dynamical pinning of domain wall in magnetic nanowire induced by Walker
  breakdown

abstract:
  Transmission probability of a domain wall through a magnetic nanowire is
investigated as a function of the external magnetic field. Very intriguing
phenomenon is found that the transmission probability shows a significant drop
after exceeding the threshold driving field, which contradicts our intuition
that a domain wall is more mobile in the higher magnetic field. The
micromagnetics simulation reveals that the domain wall motion in the wire with
finite roughness causes the dynamical pinning due to the Walker breakdown,
which semi-quantitatively explains our experimental results.


title: Riesz basis for strongly continuous groups

abstract:
  Given a Hilbert space and the generator of a strongly continuous group on
this Hilbert space. If the eigenvalues of the generator have a uniform gap, and
if the span of the corresponding eigenvectors is dense, then these eigenvectors
form a Riesz basis (or unconditional basis) of the Hilbert space. Furthermore,
we show that none of the conditions can be weakened. However, if the
eigenvalues (counted with multiplicity) can be grouped into subsets of at most
$K$ elements, and the distance between the groups is (uniformly) bounded away
from zero, then the spectral projections associated to the groups form a Riesz
family. This implies that if in every range of the spectral projection we
construct an orthonormal basis, then the union of these bases is a Riesz basis
in the Hilbert space.


title: The Hydrodynamics of Gamma-Ray Burst Remnants

abstract:
  This paper reports on the results of a numerical investigation designed to
address how the initially anisotropic appearance of a GRB remnant is modified
by the character of the circumburst medium and by the possible presence of an
accompanying supernova (SN). Axisymmetric hydrodynamical calculations of light,
impulsive jets propagating in both uniform and inhomogeneous external media are
presented, which show that the resulting dynamics of their remnants since the
onset of the non-relativistic phase is different from the standard self-similar
solutions. Because massive star progenitors are expected to have their close-in
surroundings modified by the progenitor winds, we consider both free winds and
shocked winds as possible external media for GRB remnant evolution. Abundant
confirmation is provided here of the important notion that the morphology and
visibility of GRB remnants are determined largely by their circumstellar
environments. For this reason, their detectability is highly biased in favor of
those with massive star progenitors; although, in this class of models, the
beamed component may be difficult to identify because the GRB ejecta is
eventually swept up by the accompanying SN. The number density of asymmetric
GRB remnants in the local Universe could be, however, far larger if they expand
in a tenuous interstellar medium, as expected for some short GRB progenitor
models. In these sources, the late size of the observable, asymmetric remnant
could extend over a wide, possibly resolvable angle and may be easier to
constrain directly.


title: Halo density reduction by baryonic settling?

abstract:
  We test the proposal by El-Zant et al that the dark matter density of halos
could be reduced through dynamical friction acting on heavy baryonic clumps in
the early stages of galaxy formation. Using N-body simulations, we confirm that
the inner halo density cusp is flattened to 0.2 of the halo break radius by the
settling of a single clump of mass \ga 0.5% of the halo mass. We also find that
an ensemble of 50 clumps each having masses \ga 0.2% can flatten the cusp to
almost the halo break radius on a time scale of \sim9 Gyr, for an NFW halo of
concentration 15. We summarize some of the difficulties that need to be
overcome if this mechanism is to resolve the apparent conflict between the
observed inner densities of galaxy halos and the predictions of LCDM.


title:
Generalized eigenfunctions of relativistic Schroedinger operators in two
  dimensions

abstract:
  Generalized eigenfunctions of the two-dimensional relativistic Schr\"odinger
operator $H=\sqrt{-\Delta}+V(x)$ with $|V(x)|\leq C< x>^{-\sigma}$,
$\sigma>3/2$, are considered. We compute the integral kernels of the boundary
values $R_0^\pm(\lambda)=(\sqrt{-\Delta}-(\lambda\pm i0))^{-1}$, and prove that
the generalized eigenfunctions $\phi^\pm(x,k)$ are bounded on $R_x^2\times\{k |
a\leq |k|\leq b\}$, where $[a,b]\subset(0,\infty)\backslash\sigma_p(H)$, and
$\sigma_p(H)$ is the set of eigenvalues of $H$. With this fact and the
completeness of the wave operators, we establish the eigenfunction expansion
for the absolutely continuous subspace for $H$. Finally, we show that each
generalized eigenfunction is asymptotically equal to a sum of a plane wave and
a spherical wave under the assumption that $\sigma>2$.


title:
The X-ray luminosity of solar-mass stars in the intermediate age open
  cluster NGC 752

abstract:
  AIMS. While observational evidence shows that most of the decline in a star's
X-ray activity occurs between the age of the Hyades (~8 x 10^8 yrs) and that of
the Sun, very little is known about the evolution of stellar activity between
these ages. To gain information on the typical level of coronal activity at a
star's intermediate age, we studied the X-ray emission from stars in the 1.9
Gyr old open cluster NGC 752. METHODS. We analysed a ~140 ks Chandra
observation of NGC 752 and a ~50 ks XMM-Newton observation of the same cluster.
We detected 262 X-ray sources in the Chandra data and 145 sources in the
XMM-Newton observation. Around 90% of the catalogued cluster members within
Chandra's field-of-view are detected in the X-ray. The X-ray luminosity of all
observed cluster members (28 stars) and of 11 cluster member candidates was
derived. RESULTS. Our data indicate that, at an age of 1.9 Gyr, the typical
X-ray luminosity of the cluster members with M=0.8-1.2 Msun is Lx = 1.3 x 10^28
erg s^-1, so approximately a factor of 6 less intense than that observed in the
younger Hyades. Given that Lx is proportional to the square of a star's
rotational rate, the median Lx of NGC 752 is consistent, for t > 1 Gyr, to a
decaying rate in rotational velocities v_rot ~ t^-alpha with alpha ~ 0.75,
steeper than the Skumanich relation (alpha ~ 0.5) and significantly steeper
than observed between the Pleiades and the Hyades (where alpha < 0.3),
suggesting that a change in the rotational regimes of the stellar interiors is
taking place at t ~ 1 Gyr.


title: Tropical enumerative invariants of F_0 and F_2

abstract:
  There is an equation relating numbers of curves on F_0 satisfying incidence
conditions and numbers of curves on F_2 satisfying incidence conditions. The
purpose of this paper is to give a tropical proof of this equation in the case
of rational curves. We use induction on the degree and two Kontsevich-type
formulas for curves on F_0 and on F_2. The formula for F_2 was not known before
and is proved using tropical geometry.


title: Codes on hypergraphs

abstract:
  Codes on hypergraphs are an extension of the well-studied family of codes on
bipartite graphs. Bilu and Hoory (2004) constructed an explicit family of codes
on regular t-partite hypergraphs whose minimum distance improves earlier
estimates of the distance of bipartite-graph codes. They also suggested a
decoding algorithm for such codes and estimated its error-correcting
capability.
  In this paper we study two aspects of hypergraph codes. First, we compute the
weight enumerators of several ensembles of such codes, establishing conditions
under which they attain the Gilbert-Varshamov bound and deriving estimates of
their distance. In particular, we show that this bound is attained by codes
constructed on a fixed bipartite graph with a large spectral gap.
  We also suggest a new decoding algorithm of hypergraph codes that corrects a
constant fraction of errors, improving upon the algorithm of Bilu and Hoory.


title:
Scattering for small energy solutions of NLS with periodic potential in
  1D

abstract:
  We prove scattering for small solutions to of nonlinear Schroedinger
equations in 1D with a space periodic potential


title: Influence of zonal flows on unstable drift modes in ETG turbulence

abstract:
  The linear instability of the electron temperature gradient (ETG) driven
modes in the presence of zonal flows is investigated. Random and deterministic
$cos$ - like profiles of the zonal flow are considered. It is shown that the
presence of shearing by zonal flows can stabilize the linear instability of ETG
drift modes.


title: Influence of the mean flow on zonal flow generation

abstract:
  Excitation of zonal flow by the modulational instability in the presence of
mean shear flow is considered. It is shown that the small amplitude mean flow
favours the modulational instability, increasing the growth rate, whereas
sufficiently strong mean shear significantly reduces the instability growth
rate.


title:
A model comparison of resonance lifetime modifications, a soft equation
  of state and non-Gaussian effects on $\pi-\pi$ correlations at FAIR/AGS
  energies

abstract:
  HBT correlations of $\pi^--\pi^-$ pairs at FAIR/AGS energies are investigated
by using the UrQMD transport model and the CRAB analyzing program. Three
different possible sources (treatment of resonance lifetimes, a soft equation
of state and non-Gaussian effects) to understand the HBT $R_O/R_S$ puzzle are
investigated. Firstly, we find that different treatments of the resonance decay
time can not resolve the HBT time-related puzzle, however it can modify the HBT
radii at low transverse momenta to some extent to explain the data slightly.
Secondly, with a soft equation of state with momentum dependence, the measured
transverse momentum dependent HBT radii and $R_O/R_S$ ratio can be described
fairly well. Thirdly, non-Gaussian effects are visible in the calculated
correlation function. Using the Edgeworth expansion, one finds that the
non-Gaussian effect is strongest in the longitudinal direction and weakest in
the sideward direction.


title:
A central limit theorem for the rescaled L\'evy area of two-dimensional
  fractional Brownian motion with Hurst index $H<1/4$

abstract:
  Let $B=(B^{(1)},B^{(2)})$ be a two-dimensional fractional Brownian motion
with Hurst index $\alpha\in (0,1/4)$. Using an analytic approximation $B(\eta)$
of $B$ introduced in \cite{Unt08}, we prove that the rescaled L\'evy area
process $(s,t)\to \eta^{\half(1-4\alpha)}\int_s^t dB_{t_1}^{(1)}(\eta)
\int_s^{t_1} dB_{t_2}^{(2)}(\eta)$ converges in law to $W_t-W_s$ where $W$ is a
Brownian motion independent from $B$. The method relies on a very general
scheme of analysis of singularities of analytic functions, applied to the
moments of finite-dimensional distributions of the L\'evy area.


title: Noncommutative Deformations of Wightman Quantum Field Theories

abstract:
  Quantum field theories on noncommutative Minkowski space are studied in a
model-independent setting by treating the noncommutativity as a deformation of
quantum field theories on commutative space. Starting from an arbitrary
Wightman theory, we consider special vacuum representations of its Weyl-Wigner
deformed counterpart. In such representations, the effect of the
noncommutativity on the basic structures of Wightman theory, in particular the
covariance, locality and regularity properties of the fields, the structure of
the Wightman functions, and the commutative limit, is analyzed. Despite the
nonlocal structure introduced by the noncommutativity, the deformed quantum
fields can still be localized in certain wedge-shaped regions, and may
therefore be used to compute noncommutative corrections to two-particle
S-matrix elements.


title: First-principles investigation of effect of pressure on BaFe$_2$As$_2$

abstract:
  On experimental side, BaFe$_2$As$_2$ without doping has been made
superconducting by applying appropriate pressure (2-6 GPa). Here, we use a
full-potential linearized augmented plane wave method within the
density-functional theory to investigate the effect of pressure on its crystal
structure, magnetic order, and electronic structure. Our calculations show that
the striped antiferromagnetic order observed in experiment is stable against
pressure up to 13 GPa. Calculated antiferromagnetic lattice parameters are in
good agreements with experimental data, while calculations with nonmagnetic
state underestimate Fe-As bond length and c-axis lattice constant. The effects
of pressure on crystal structure and electronic structure are investigated for
both the antiferromagnetic state and the nonmagnetic one. We find that the
compressibility of the antiferromagnetic state is quite isotropic up to about
6.4 GPa. With increasing pressure, the FeAs$_4$ tetrahedra is hardly distorted.
We observe a transition of Fermi surface topology in the striped
antiferromagnetic state when the compression of volume is beyond 8% (or
pressure 6 GPa), which corresponds to a large change of $c/a$ ratio. These
first-principles results should be useful to understanding the
antiferromagnetism and electronic states in the FeAs-based materials, and may
have some useful implications to the superconductivity.


title: BV photometry of a possible open star cluster pair NGC 7031/NGC 7086

abstract:
  We present a CCD BV photometry of the possible binary open star cluster NGC
7031/NGC 7086. The aim is to confirm or disprove their common nature on the
grounds of their age and distance. An age of 224 $\pm$ 25 Myr and distance 831
$\pm$ 72 pc was determined for NGC 7031 and 178 $\pm$ 25 Myr, 955 $\pm$ 84 pc
for NGC 7086, respectively. Based on these differences in age and distance we
conclude that the two clusters are most likely not formed together from one and
the same Giant Molecular Cloud and thus are not a true binary cluster.


title:
An oscillating, homogeneous and isotropic Universe from Scalar-Tensor
  gravity

abstract:
  An oscillating, homogeneous and isotropic Universe which arises from
Scalar-Tensor gravity is discussed in the linearized approach, showing that
some observative evidences like the Hubble Law and the Cosmological Redshift
are in agreement with the model. In this context Dark Energy appears like a
pure curvature effect arising by the scalar field.


title: Contact mechanics with adhesion: Interfacial separation and contact area

abstract:
  We study the adhesive contact between elastic solids with randomly rough,
self affine fractal surfaces. We present molecular dynamics (MD) simulation
results for the interfacial stress distribution and the wall-wall separation.
We compare the MD results for the relative contact area and the average
interfacial separation, with the prediction of the contact mechanics theory of
Persson. We find good agreement between theory and the simulation results. We
apply the theory to the system studied by Benz et al. involving polymer in
contact with polymer, but in this case the adhesion gives only a small
modification of the interfacial separation as a function of the squeezing
pressure.


title:
Long-term AGILE monitoring of the puzzling gamma-ray source 3EG
  J1835+5918

abstract:
  We present the AGILE gamma-ray observations of the field containing the
puzzling gamma-ray source 3EG J1835+5918. This source is one of the most
remarkable unidentified EGRET sources. An unprecedentedly long AGILE monitoring
of this source yields important information on the positional error box, flux
evolution, and spectrum. 3EG J1835+5918 has been in the AGILE field of view
several times in 2007 and 2008 for a total observing time of 138 days from 2007
Sept 04 to 2008 June 30 encompassing several weeks of continuous coverage. With
an exposure time approximately twice that of EGRET, AGILE confirms the
existence of a prominent gamma-ray source (AGL J1836+5926) at a position
consistent with that of EGRET, although with a remarkably lower average flux
value for photon energies greater than 100 MeV. A 5-day bin temporal analysis
of the whole data set of AGL J1836+5926 shows some evidence for variability of
the gamma-ray flux. The source spectrum between 100 MeV and 1 GeV can be fitted
with a power law with photon index in the range 1.6-1.7, fully consistent with
the EGRET value. The faint X-ray source RX J1836.2+5925 that has been proposed
as a possible counterpart of 3EG J1835+5918 is well within the AGILE error box.
Future continuous monitoring (both by AGILE and GLAST) is needed to confirm the
gamma-ray flux variability and to unveil the source origin, a subject that is
currently being pursued through a multiwavelength search for counterparts.


title: Achieving the threshold regime with an over-screened Josephson junction

abstract:
  We demonstrate that by utilizing an over-screened Josephson junction as a
noise detector it is possible to achieve the threshold regime, whereby the
tails of the fluctuating current distribution are measured. This situation is
realized by placing the Josephson junction and mesoscopic conductor in an
external circuit with very low impedance. In the underdamped limit,
over-screening the junction inhibits the energy diffusion in the junction,
effectively creating a tunable activation barrier to the dissipative state. As
a result, the activation rate is qualitatively different from the Arrhenius
form.


title:
On sequential Monte Carlo, partial rejection control and approximate
  Bayesian computation

abstract:
  We present a sequential Monte Carlo sampler variant of the partial rejection
control algorithm, and show that this variant can be considered as a sequential
Monte Carlo sampler with a modified mutation kernel. We prove that the new
sampler can reduce the variance of the incremental importance weights when
compared with standard sequential Monte Carlo samplers. We provide a study of
theoretical properties of the new algorithm, and make connections with some
existing algorithms. Finally, the sampler is adapted for application under the
challenging "likelihood free," approximate Bayesian computation modelling
framework, where we demonstrate superior performance over existing
likelihood-free samplers.


title: Generalized mean curvature flow in Carnot groups

abstract:
  In this paper we study the generalized mean curvature flow of sets in the
sub-Riemannian geometry of Carnot groups. We extend to our context the level
sets method and the weak (viscosity) solutions introduced in the Euclidean
setting by Evans-Spruck and Chen-Giga-Goto. We establish two special cases of
the comparison principle, existence, uniqueness and basic geometric properties
of the flow.


title:
Stable three-dimensional spatially modulated vortex solitons in
  Bose-Einstein condensates

abstract:
  We present exact numerical solutions in the form of spatially localized
three-dimensional (3D) nonrotating and rotating (azimuthon) multipole solitons
in the Bose-Einstein condensate (BEC) confined by a parabolic trap. We
numerically show that the 3D azimuthon solutions exist as a continuous family
parametrized by the angular velocity (or, equivalently, the modulational
depth). By a linear stability analysis we show that 3D azimuthons with a
sufficiently large phase modulational depth can be stable. The results are
confirmed by direct numerical simulations of the Gross-Pitaevskii equation.


title:
Theoretical prediction and experimental study of a ferromagnetic shape
  memory alloy: Ga_2MnNi

abstract:
  We predict the existence of a new ferromagnetic shape memory alloy Ga_2MnNi
using density functional theory. The martensitic start temperature (T_M) is
found to be approximately proportional to the stabilization energy of the
martensitic phase (deltaE_tot) for different shape memory alloys. Experimental
studies performed to verify the theoretical results show that Ga_2MnNi is
ferromagnetic at room temperature and the T_M and T_C are 780K and 330K,
respectively. Both from theory and experiment, the martensitic transition is
found to be volume conserving that is indicative of shape memory behavior.


title:
Weighted power counting and Lorentz violating gauge theories. I: General
  properties

abstract:
  We construct local, unitary gauge theories that violate Lorentz symmetry
explicitly at high energies and are renormalizable by weighted power counting.
They contain higher space derivatives, which improve the behavior of
propagators at large momenta, but no higher time derivatives. We show that the
regularity of the gauge-field propagator privileges a particular spacetime
breaking, the one into into space and time. We then concentrate on the simplest
class of models, study four dimensional examples and discuss a number of issues
that arise in our approach, such as the low-energy recovery of Lorentz
invariance.


title: Dijet azimuthal distributions and initial-state parton showers

abstract:
  We investigate angular correlations in multi-jet final states at high-energy
colliders and discuss their sensitivity to initial-state showering effects,
including QCD coherence and corrections to collinear ordering.


title: Nonlinear regularization techniques for seismic tomography

abstract:
  The effects of several nonlinear regularization techniques are discussed in
the framework of 3D seismic tomography. Traditional, linear, $\ell_2$ penalties
are compared to so-called sparsity promoting $\ell_1$ and $\ell_0$ penalties,
and a total variation penalty. Which of these algorithms is judged optimal
depends on the specific requirements of the scientific experiment. If the
correct reproduction of model amplitudes is important, classical damping
towards a smooth model using an $\ell_2$ norm works almost as well as
minimizing the total variation but is much more efficient. If gradients (edges
of anomalies) should be resolved with a minimum of distortion, we prefer
$\ell_1$ damping of Daubechies-4 wavelet coefficients. It has the additional
advantage of yielding a noiseless reconstruction, contrary to simple $\ell_2$
minimization (`Tikhonov regularization') which should be avoided. In some of
our examples, the $\ell_0$ method produced notable artifacts. In addition we
show how nonlinear $\ell_1$ methods for finding sparse models can be
competitive in speed with the widely used $\ell_2$ methods, certainly under
noisy conditions, so that there is no need to shun $\ell_1$ penalizations.


title:
Impurity suppression of the critical temperature in the iron-based
  superconductors

abstract:
  We study the impurity suppression of the critical temperature $T_c$ of the
FeAs superconductors theoretically based on the the $\pm$s-wave pairing state
of a two band model. The effects of non-magnetic and magnetic impurities are
studied with the $\mathcal{T}$-matrix approximation, which can continuously
treat impurity scattering from weak to strong coupling limit. We found that
both magnetic and non-magnetic impurities suppress $T_c$ with a rate that is
practically indistinguishable from the standard d-wave case despite a possibly
large difference of the positive and negative s-wave order parameter (OP)
magnitudes. This is because the density of states enters together with the OP
magnitude for the scattering process.