title: Logarithmic boundary layers in highly turbulent Taylor-Couette flow

abstract:
  We provide direct measurements of the boundary layer properties in highly
turbulent Taylor-Couette flow up to $\text{Ta}=6.2 \times 10^{12}$ using
high-resolution particle image velocimetry (PIV). We find that the mean
azimuthal velocity profile at the inner and outer cylinder can be fitted by the
von K\'arm\'an log law $u^+ = \frac 1\kappa \ln y^+ +B$. The von K\'arm\'an
constant $\kappa$ is found to depend on the driving strength $\text{Ta}$ and
for large $\text{Ta}$ asymptotically approaches $\kappa \approx 0.40$. The
variance profiles of the local azimuthal velocity have a universal peak around
$y^+ \approx 12$ and collapse when rescaled with the driving velocity (and not
with the friction velocity), displaying a log-dependence of $y^+$ as also found
for channel and pipe flows [1,2].


title: A Note on Inextensible Flows of Curves in E^n,1

abstract:
  In this paper, we study inextensible flows of non-null curves in E^n,1. We
give necessary and sufficient conditions for inextensible flow of nonnull
curves in E^n,1.


title: Sub-exponential mixing of open systems with particle-disk interactions

abstract:
  We consider a class of mechanical particle systems with deterministic
particle-disk interactions coupled to Gibbs heat reservoirs at possibly
different temperatures. We show that there exists a unique (non-equilibrium)
steady state. This steady state is mixing, but not exponentially mixing, and
all initial distributions converge to it. In addition, for a class of initial
distributions, the rates of converge to the steady state are sub-exponential.


title: The necessary and sufficient conditions of copositive tensors

abstract:
  In this paper, it is proved that (strict) copositivity of a symmetric tensor
$\mathcal{A}$ is equivalent to the fact that every principal sub-tensor of
$\mathcal{A}$ has no a (non-positive) negative $H^{++}$-eigenvalue. The
necessary and sufficient conditions are also given in terms of the
$Z^{++}$-eigenvalue of the principal sub-tensor of the given tensor. This
presents a method of testing (strict) copositivity of a symmetric tensor by
means of the lower dimensional tensors. Also the equivalent definition of
strictly copositive tensors is given on entire space $\mathbb{R}^n$.


title:
Eigenvalue analysis of constrained minimization problem for homogeneous
  polynomial

abstract:
  In this paper, the concepts of Pareto $H$-eigenvalue and Pareto
$Z$-eigenvalue are introduced for studying constrained minimization problem and
the necessary and sufficient conditions of such eigenvalues are given. It is
proved that a symmetric tensor has at least one Pareto $H$-eigenvalue (Pareto
$Z$-eigenvalue). Furthermore, the minimum Pareto $H$-eigenvalue (or Pareto
$Z$-eigenvalue) of a symmetric tensor is exactly equal to the minimum value of
constrained minimization problem of homogeneous polynomial deduced by such a
tensor, which gives an alternative methods for solving the minimum value of
constrained minimization problem. In particular, a symmetric tensor
$\mathcal{A}$ is copositive if and only if every Pareto $H$-eigenvalue
($Z-$eigenvalue) of $\mathcal{A}$ is non-negative.


title:
Semiclassical black holes expose forbidden charges and censor divergent
  densities

abstract:
  Classically, the black hole (BH) horizon is a rigid surface of infinite
redshift; whereas the uncertainty principle dictates that the semiclassical
(would-be) horizon cannot be fixed in space nor can it exhibit any divergences.
We propose that this distinction underlies the BH information-loss paradox, the
apparent absence of BH hair, the so-called trans-Planckian problem and the
recent "firewall" controversy. We argue that the correct prescription is to
first integrate out the fluctuations of the background geometry and only then
evaluate matter observables. The basic idea is illustrated using a system of
two strongly coupled harmonic oscillators, with the heavier oscillator
representing the background. We then apply our proposal to matter fields near a
BH horizon, initially treating the matter fields as classical and the
background as semiclassical. In this case, the average value of the associated
current does not vanish; so that it is possible, in principle, to measure the
global charge of the BH. Then the matter is, in addition to the background,
treated quantum mechanically. We show that the average energy density of matter
as seen by an asymptotic observer is finite and proportional to the BH entropy,
rather than divergent. We discuss the implications of our results for the
various controversial issues concerning BH physics.


title: Lattice calculations of Ds to eta and eta' decay form factors

abstract:
  We report on lattice results of the form factors for semi-leptonic decays of
the D_s meson to eta and eta', with n_f=2+1 configurations. The calculation
contains disconnected fermion loop diagrams, which are challenging to calculate
on the lattice. Our result shows that the disconnected diagrams give
significant contributions to the form factors.


title: An efficient algorithm for structured sparse quantile regression

abstract:
  Quantile regression is studied in combination with a penalty which promotes
structured (or group) sparsity. A mixed $\ell_{1,\infty}$-norm on the parameter
vector is used to impose structured sparsity on the traditional quantile
regression problem. An algorithm is derived to calculate the piece-wise linear
solution path of the corresponding minimization problem. A Matlab
implementation of the proposed algorithm is provided and some applications of
the methods are also studied.


title: Asymptotic states of generalized universes with higher derivatives

abstract:
  We review ongoing research related to the asymptotic dynamics of isotropic
universes in theories with higher derivatives, especially near the initial
singularity. We treat two major cases, that is universes in vacuum, and also
those filled with radiation using the method of asymptotic splittings of vector
fields. Our solutions have the form of formal Fuchsian-type series for the
basic unknowns and are valid near collapse or big rip regimes asymptotically.


title:
Stochastic acceleration by multi-island contraction during turbulent
  magnetic reconnection

abstract:
  The acceleration of charged particles in magnetized plasmas is considered
during turbulent multi-island magnetic reconnection. The particle acceleration
model is constructed for an ensemble of islands which produce adiabatic
compression of the particles. The model takes into account the statistical
fluctuations in the compression rate experienced by the particles during their
transport in the acceleration region. The evolution of the particle
distribution function is described as a simultaneous first and second-order
Fermi acceleration process. While the efficiency of the first-order process is
controlled by the average rate of compression, the second order process
involves the variance in the compression rate. Moreover, the acceleration
efficiency associated with the second-order process involves both the Eulerian
properties of the compression field and the Lagrangian properties of the
particles. The stochastic contribution to the acceleration is non-resonant and
can dominate the systematic part in the case of a large variance in the
compression rate. The model addresses the role of the second-order process, how
the latter can be related to the large-scale turbulent transport of particles
and explains some features of the numerical simulations of particle
acceleration by multi-island contraction during magnetic reconnection.


title: A new method of pulse-wise spectral analysis of Gamma-ray Bursts

abstract:
  Time-resolved spectral analysis, though a very promising method to understand
the emission mechanism of gamma-ray bursts (GRBs), is difficult to implement in
practice because of poor statistics. We present a new method for pulse-wise
time-resolved spectral study of the individual pulses of GRBs, using the fact
that many spectral parameters are either constants or smooth functions of time.
We use this method for the two pulses of GRB 081221, the brightest GRB with
separable pulses. We choose, from the literature, a set of possible models
which includes the Band model, blackbody with a power-law (BBPL), a collection
of black bodies with a smoothly varying temperature profile, along with a
power-law (mBBPL), and two blackbodies with a power-law (2BBPL). First, we
perform time-resolved study to confirm the spectral parameter variations, and
then construct the new model to perform a joint spectral fit. We find that any
photospheric emission in terms of black bodies is required mainly in the rising
parts of the pulses and the falling part can be adequately explained in terms
of the Band model, with the low energy photon index within the regime of
synchrotron model. Interestingly, we find that 2BBPL is comparable or sometimes
even better, though marginally, than the Band model, in all episodes.
Consistent results are also obtained for the brightest GRB of Fermi era --- GRB
090618. We point out that the method is generic enough to test any spectral
model with well defined parameter variations.


title: The HERMES Recoil Detector

abstract:
  For the final running period of HERA, a recoil detector was installed at the
HERMES experiment to improve measurements of hard exclusive processes in
charged-lepton nucleon scattering. Here, deeply virtual Compton scattering is
of particular interest as this process provides constraints on generalised
parton distributions that give access to the total angular momenta of quarks
within the nucleon. The HERMES recoil detector was designed to improve the
selection of exclusive events by a direct measurement of the four-momentum of
the recoiling particle. It consisted of three components: two layers of
double-sided silicon strip sensors inside the HERA beam vacuum, a two-barrel
scintillating fibre tracker, and a photon detector. All sub-detectors were
located inside a solenoidal magnetic field with an integrated field strength of
1 T. The recoil detector was installed in late 2005. After the commissioning of
all components was finished in September 2006, it operated stably until the end
of data taking at HERA end of June 2007. The present paper gives a brief
overview of the physics processes of interest and the general detector design.
The recoil detector components, their calibration, the momentum reconstruction
of charged particles, and the event selection are described in detail. The
paper closes with a summary of the performance of the detection system.


title:
On the analogue of the concavity of entropy power in the Brunn-Minkowski
  theory

abstract:
  Elaborating on the similarity between the entropy power inequality and the
Brunn-Minkowski inequality, Costa and Cover conjectured in {\it On the
similarity of the entropy power inequality and the Brunn-Minkowski inequality}
(IEEE Trans. Inform. Theory 30 (1984), no. 6, 837-839) the
$\frac{1}{n}$-concavity of the outer parallel volume of measurable sets as an
analogue of the concavity of entropy power. We investigate this conjecture and
study its relationship with geometric inequalities.


title: On the Number of Eisenstein Polynomials of Bounded Height

abstract:
  We obtain a more precise version of an asymptotic formula of A. Dubickas for
the number of monic Eisenstein polynomials of fixed degree $d$ and of height at
most $H$, as $H\to \infty$. In particular, we give an explicit bound for the
error term. We also obtain an asymptotic formula for arbitrary Eisenstein
polynomials of height at most $H$.


title:
Modular Anomaly from Holomorphic Anomaly in Mass Deformed N=2
  Superconformal Field Theories

abstract:
  We study the instanton partition functions of two well-known superconformal
field theories with mass deformations. Two types of anomaly equations, namely,
the modular anomaly and holomorphic anomaly, have been discovered in the
literature. We provide a clean solution to the long standing puzzle about their
precise relation, and obtain some universal formulas. We show that the
partition function is invariant under the SL(2,Z) duality which exchanges
theories at strong coupling with those of weak coupling.


title: Elements with only negative cycles in Weyl groups of type $B$ and $D$

abstract:
  We give a precise formula and a simple asymptotic function for the proportion
of elements with only negative (or only positive) cycles in Weyl groups of type
$B,C$ and $D$.


title: On Shifted Eisenstein Polynomials

abstract:
  We study polynomials with integer coefficients which become Eisenstein
polynomials after the additive shift of a variable. We call such polynomials
shifted Eisenstein polynomials. We determine an upper bound on the maximum
shift that is needed given a shifted Eisenstein polynomial and also provide a
lower bound on the density of shifted Eisenstein polynomials, which is strictly
greater than the density of classical Eisenstein polynomials. We also show that
the number of irreducible degree $n$ polynomials that are not shifted
Eisenstein polynomials is infinite. We conclude with some numerical results on
the densities of shifted Eisenstein polynomials.


title: VLA OH Zeeman Observations of the star forming region S88B

abstract:
  We present observations of the Zeeman effect in OH thermal absorption main
lines at 1665 and 1667 MHz taken with the Very Large Array (VLA) toward the
star forming region S88B. The OH absorption profiles toward this source are
complicated, and contain several blended components toward a number of
positions. Almost all of the OH absorbing gas is located in the eastern parts
of S88B, toward the compact continuum source S88B-2 and the eastern parts of
the extended continuum source S88B-1. The ratio of 1665/1667 MHz OH line
intensities indicates the gas is likely highly clumped, in agreement with other
molecular emission line observations in the literature. S88-B appears to
present a similar geometry to the well-known star forming region M17, in that
there is an edge-on eastward progression from ionized to molecular gas. The
detected magnetic fields appear to mirror this eastward transition; we detected
line-of-sight magnetic fields ranging from 90-400 \mu G, with the lowest values
of the field to the southwest of the S88B-1 continuum peak, and the highest
values to its northeast. We used the detected fields to assess the importance
of the magnetic field in S88B by a number of methods; we calculated the ratio
of thermal to magnetic pressures, we calculated the critical field necessary to
completely support the cloud against self-gravity and compared it to the
observed field, and we calculated the ratio of mass to magnetic flux in terms
of the critical value of this parameter. All these methods indicated that the
magnetic field in S88B is dynamically significant, and should provide an
important source of support against gravity. Moreover, the magnetic energy
density is in approximate equipartition with the turbulent energy density,
again pointing to the importance of the magnetic field in this region.


title: Optimal damping algorithm for unrestricted Hartree-Fock calculations

abstract:
  We have developed a couple of optimal damping algorithms (ODAs) for
unrestricted Hartree-Fock (UHF) calculations of open-shell molecular systems. A
series of equations were derived for both concurrent and alternate
constructions of alpha- and beta-Fock matrices in the integral-direct
self-consistent-field (SCF) procedure. Several test calculations were performed
to check the convergence behaviors. It was shown that the concurrent algorithm
provides better performance than does the alternate one.


title: Velocity Relaxation in a Strongly Coupled Plasma

abstract:
  Collisional relaxation of Coulomb systems is studied in the strongly coupled
regime. We use an optical pump-probe approach to manipulate and monitor the
dynamics of ions in an ultracold neutral plasma, which allows direct
measurement of relaxation rates in a regime where common Landau-Spitzer theory
breaks down. Numerical simulations confirm the experimental results and display
non-Markovian dynamics at early times.


title: Ore localization and minimal injective resolutions

abstract:
  In this paper, we describe the structure of the localization of
Ext^{i}_{R}(R/P,M), where P is a prime ideal and M is a module, at certain Ore
sets X. We first study the situation for FBN rings, and then consider matters
for a large class of Auslander-Gorenstein rings. We need to impose suitable
homological regularity conditions to get results in the more general situation.
The results obtained are then used to study the shape of minimal injective
resolutions of modules over noetherian rings.


title: Functional Data Analysis with Increasing Number of Projections

abstract:
  Functional principal components (FPC's) provide the most important and most
extensively used tool for dimension reduction and inference for functional
data. The selection of the number, d, of the FPC's to be used in a specific
procedure has attracted a fair amount of attention, and a number of reasonably
effective approaches exist. Intuitively, they assume that the functional data
can be sufficiently well approximated by a projection onto a finite-dimensional
subspace, and the error resulting from such an approximation does not impact
the conclusions. This has been shown to be a very effective approach, but it is
desirable to understand the behavior of many inferential procedures by
considering the projections on subspaces spanned by an increasing number of the
FPC's. Such an approach reflects more fully the infinite-dimensional nature of
functional data, and allows to derive procedures which are fairly insensitive
to the selection of d. This is accomplished by considering limits as d tends to
infinity with the sample size.
  We propose a specific framework in which we let d tend to infinity by
deriving a normal approximation for the two-parameter partial sum process of
the scores \xi_{i,j} of the i-th function with respect to the j-th FPC. Our
approximation can be used to derive statistics that use segments of
observations and segments of the FPC's. We apply our general results to derive
two inferential procedures for the mean function: a change-point test and a
two-sample test. In addition to the asymptotic theory, the tests are assessed
through a small simulation study and a data example.


title:
Minimax rates of convergence for Wasserstein deconvolution with
  supersmooth errors in any dimension

abstract:
  The subject of this paper is the estimation of a probability measure on
${\mathbb R}^d$ from data observed with an additive noise, under the
Wasserstein metric of order $p$ (with $p\geq 1$). We assume that the
distribution of the errors is known and belongs to a class of supersmooth
distributions, and we give optimal rates of convergence for the Wasserstein
metric of order $p$. In particular, we show how to use the existing lower
bounds for the estimation of the cumulative distribution function in dimension
one to find lower bounds for the Wasserstein deconvolution in any dimension.


title: H{\"o}rmander Functional Calculus for Poisson Estimates

abstract:
  The aim of the article is to show a H{\"o}rmander spectral multiplier theorem
for an operator $A$ whose kernel of the semigroup $\exp(-zA)$ satisfies certain
Poisson estimates for complex times $z.$ Here $\exp(-zA)$ acts on
$L^p(\Omega),\,1 < p < \infty,$ where $\Omega$ is a space of homogeneous type
with the additional condition that the measure of annuli is controlled. In most
of the known H{\"o}rmander type theorems in the literature, Gaussian bounds and
self-adjointness for the semigroup are needed, whereas here the new feature is
that the assumptions are the to some extend weaker Poisson bounds, and $\HI$
calculus in place of self-adjointness. The order of derivation in our
H{\"o}rmander multiplier result is typically $\frac{d}{2},$ $d$ being the
dimension of the space $\Omega.$ Moreover the functional calculus resulting
from our H{\"o}rmander theorem is shown to be $R$-bounded. Finally, the result
is applied to some examples.


title:
Image restoration using sparse approximations of spatially varying blur
  operators in the wavelet domain

abstract:
  Restoration of images degraded by spatially varying blurs is an issue of
increasing importance in the context of photography, satellite or microscopy
imaging. One of the main difficulty to solve this problem comes from the huge
dimensions of the blur matrix. It prevents the use of naive approaches for
performing matrix-vector multiplications. In this paper, we propose to
approximate the blur operator by a matrix sparse in the wavelet domain. We
justify this approach from a mathematical point of view and investigate the
approximation quality numerically. We finish by showing that the sparsity
pattern of the matrix can be pre-defined, which is central in tasks such as
blind deconvolution.


title:
Matrices de Toeplitz tronqu\'ees sur des polygones convexes. Cas du
  triangle

abstract:
  We consider the class of positive bounded and semi-continuous functions
defined on the two dimensional torus If f belongs to this class, then f will be
considered as the symbol of a Toeplitz operator truncated on a triangle
parametrised by an integer number . We develop a geometric structure of the
inverse of the Toeplitz operator and give an asymptotical development of the
trace of its inverse wich brings out the geometry of the triangle. The
foundation of this result consists in the possibility of f having a
factorisation of type |g|^2 where the spectrum of g will be localised in a
given semi-cone. This trace theorem allows in particular to find again the
Linnik-Szeg\"o theorem about the asymptotical evaluation of the determinant of
the truncated Toeplitz operator (or Toeplitz matrix)


title:
Storage Ring Cross Section Measurements for Electron Impact Single and
  Double Ionization of Fe^13+ and Single Ionization of Fe^16+ and Fe^17+

abstract:
  We report measurements of electron impact ionization (EII) for Fe^13+,
Fe^16+, and Fe^17+ over collision energies from below threshold to above 3000
eV. The ions were recirculated using an ion storage ring. Data were collected
after a sufficiently long time that essentially all the ions had relaxed
radiatively to their ground state before data were collected. For single
ionization of $\fethirteen$ we find that previous single pass experiments are
more than 40% larger than our results. Compared to our work, the theoretical
cross section recommended by Arnaud & Raymond (1992) is more than 30% larger,
while that of Dere (2007) is about 20% greater. Much of the discrepancy with
Dere (2007) is due to the theory overestimating the contribution of
excitation-autoionization via n=2 excitations. Double ionization of Fe^13+ is
dominated by direct ionization of an inner shell electron accompanied by
autoionization of a second electron. Our results for single ionization of
Fe^16+ and Fe^17+ agree with theoretical calculations to within the
experimental uncertainties.


title: Strongly Coupled Plasmas via Rydberg-Blockade of Cold Atoms

abstract:
  We propose and analyze a new scheme to produce ultracold neutral plasmas deep
in the strongly coupled regime. The method exploits the interaction blockade
between cold atoms excited to high-lying Rydberg states and therefore does not
require substantial extensions of current ultracold plasma experiments.
Extensive simulations reveal a universal behavior of the resulting Coulomb
coupling parameter, providing a direct connection between the physics of
strongly correlated Rydberg gases and ultracold plasmas. The approach is shown
to reduce currently accessible temperatures by more than an order of magnitude,
which opens up a new regime for ultracold plasma research and cold ion-beam
applications with readily available experimental techniques.


title: Social Resilience in Online Communities: The Autopsy of Friendster

abstract:
  We empirically analyze five online communities: Friendster, Livejournal,
Facebook, Orkut, Myspace, to identify causes for the decline of social
networks. We define social resilience as the ability of a community to
withstand changes. We do not argue about the cause of such changes, but
concentrate on their impact. Changes may cause users to leave, which may
trigger further leaves of others who lost connection to their friends. This may
lead to cascades of users leaving. A social network is said to be resilient if
the size of such cascades can be limited. To quantify resilience, we use the
k-core analysis, to identify subsets of the network in which all users have at
least k friends. These connections generate benefits (b) for each user, which
have to outweigh the costs (c) of being a member of the network. If this
difference is not positive, users leave. After all cascades, the remaining
network is the k-core of the original network determined by the cost-to-benefit
c/b ratio. By analysing the cumulative distribution of k-cores we are able to
calculate the number of users remaining in each community. This allows us to
infer the impact of the c/b ratio on the resilience of these online
communities. We find that the different online communities have different
k-core distributions. Consequently, similar changes in the c/b ratio have a
different impact on the amount of active users. As a case study, we focus on
the evolution of Friendster. We identify time periods when new users entering
the network observed an insufficient c/b ratio. This measure can be seen as a
precursor of the later collapse of the community. Our analysis can be applied
to estimate the impact of changes in the user interface, which may temporarily
increase the c/b ratio, thus posing a threat for the community to shrink, or
even to collapse.


title: Modern trends in Superconductivity and Superfluidity. Chapters 11, 13

abstract:
  In Chapter 11 we present Fermi-gas approach for the search of s-wave and
p-wave superfluidity in three-dimensional solutions of He-3 in He-4 and in He-3
submonolayers. In Chapter 13 on the basis of the anisotropic and isotropic t-J
models we study spin-charge separation and confinement in ladder systems and in
high-Tc superconductors.


title: Towards degeneracy problem breaking by large scale structures methods

abstract:
  An arguable aspect of the modified gravity theories is that many of them
present the so-called degeneracy problem. For instance, the cosmological
evolution, gravitational collapse and the main features of standard black-hole
configurations, can be mimicked by many of those theories. In this
communication we revise briefly the appropriate observable quantities to be
measured in order to discard alternative theories to LCDM, such as the observed
growth of scalar perturbations with Sloan data and the CMB tensor perturbations
evolution.


title:
Periodicity of the time-dependent Kohn-Sham equation and the Floquet
  theorem

abstract:
  The Floquet theorem allows to reformulate periodic time-dependent problems
such as the interaction of a many-body system with a laser field in terms of
time-independent, field-dressed states, also known as Floquet states. If this
was possible for density functional theory as well, one could reduce in such
cases time-dependent density functional theory to a time-independent Floquet
density functional theory. We analyze under which conditions the Floquet
theorem is applicable in a density-functional framework. By employing numerical
{\em ab initio} solutions of the interacting time-dependent Schr\"odinger
equation with time-periodic external potentials we show that the exact
effective potential in the corresponding Kohn-Sham equation is {\em not}
unconditionally periodic. Whenever several Floquet states in the interacting
system are involved in a physical process the corresponding
Hartree-exchange-correlation potential is not periodic with the external
frequency only. Using an analytically solvable example we demonstrate that, in
general, the periodicity of the time-dependent Kohn-Sham Hamiltonian cannot be
restored by choosing a different initial state. Only if the external periodic
potential is sufficiently weak such that the initial state of the interacting
system evolves adiabatically to a single, field-dressed state, the resulting
Kohn-Sham system admits the application of the Floquet theorem.


title: Matching four-point functions in higher spin AdS_3/CFT_2

abstract:
  Working in the context of the proposed duality between 3D higher spin gravity
and 2D W_N minimal model CFTs, we compute a class of four-point functions in
the bulk and on the boundary, and demonstrate precise agreement between them.
This is the first computation of a correlator in 3D higher spin gravity whose
functional form is not fixed by conformal invariance. In the bulk we make use
of elegant methods to solve the scalar field equation using only matrix
manipulations, while on the CFT side we employ the Coulomb gas representation.
Comparison is made in the semiclassical limit, in which the central charge is
taken to infinity at fixed N. Along the way, we establish the rules for
computing correlation functions of multi-trace operators in higher spin
gravity. The method involves solving the scalar master field equation in a
general representation of the bulk gauge algebra. Although most of our work is
carried out for the bulk theory based on sl(N) x sl(N), we also discuss how our
methods can be adapted to the hs[\lambda] x hs[\lambda] theory, which is
relevant in the 't Hooft limit.


title:
Anisotropic Monopole Heat Transport in the Spin-Ice Compound
  Dy$_2$Ti$_2$O$_7$

abstract:
  We report a study of the thermal conductivity $\kappa$ of the spin-ice
material Dy$_2$Ti$_2$O$_7$. From the anisotropic magnetic-field dependence of
\kappa$ and by additional measurements on the phononic reference compounds
Y$_2$Ti$_2$O$_7$ and DyYTi$_2$O$_7$, we are able to separate the phononic and
the magnetic contributions to the total heat transport, i.e. $\kappa_{ph}$ and
$\kappa_{mag}$, respectively, which both depend on the magnetic field. The
field dependent $\kappa_{ph}$ arises from lattice distortions due to
magnetic-field induced torques on the non-collinear magnetic moments of the Dy
ions. For $\kappa_{mag}$, we observe a highly anisotropic magnetic-field
dependence, which correlates with the corresponding magnetization data
reflecting the different magnetic-field induced spin-ice ground states. The
magnitude of $\kappa_{mag}$ increases with the degree of the ground-state
degeneracy. This anisotropic field dependence as well as various hysteresis
effects suggest that $\kappa_{mag}$ is essentially determined by the mobility
of the magnetic monopole excitations in spin ice.


title:
The Homogeneous Study of Transiting Systems (HoSTS) I. The Pilot Study
  of WASP-13

abstract:
  We present the fundamental stellar and planetary properties of the transiting
planetary system WASP-13 within the framework of the Homogeneous Study of
Transiting Systems (HoSTS). HoSTS aims to derive the fundamental stellar (Teff,
[Fe/H], Mstar, Rstar), and planetary (Mpl, Rpl, Teq) physical properties of
known transiting planets using a consistent methodology and homogeneous
high-quality dataset. Four spectral analysis techniques are independently
applied to a Keck+HIRES spectrum of WASP-13 considering two distinct cases:
unconstrained parameters, and constrained log g from transit light curves. We
check the derived stellar temperature against that from a different temperature
diagnostic based on an INT+IDS H{\alpha} spectrum. The four unconstrained
analyses render results that are in good agreement, and provide an improvement
of 50% in the precision of Teff, and of 85% in [Fe/H] with respect to the
WASP-13 discovery paper. The planetary parameters are then derived via the
Monte-Carlo-Markov-Chain modeling of the radial velocity and light curves, in
iteration with stellar evolutionary models to derive realistic uncertainties.
WASP-13 (1.187 +- 0.065 Msun; 1.574 +- 0.048 Rsun) hosts a Saturn-mass,
transiting planet (0.500 +- 0.037 MJup; 1.407 +- 0.052 RJup), and is at the end
of its main-sequence lifetime (4-5.5 Gyr). Our analysis of WASP-13 showcases
that both a detailed stellar characterization, and transit modeling are
necessary to well determine the fundamental properties of planetary systems,
which are paramount in identifying and determining empirical relationships
between transiting planets and their hosts.


title: Grove-Shiohama type sphere theorem in Finsler geometry

abstract:
  From radial curvature geometry's standpoint, we prove a sphere theorem of the
Grove-Shiohama type for a certain class of compact Finsler manifolds.


title:
Identification of newly-discovered sources belonging to the 4th IBIS
  catalog and to the 54 months Palermo Swift/BAT catalog

abstract:
  The most recent all-sky surveys performed with the INTEGRAL and SWIFT
satellites allowed the detection of more than 1500 sources in hard X-rays above
20 keV. About one quarter of them has no obvious counterpart at other
wavelengths and therefore could not be associated with any known class of
high-energy emitting objects. Although cross-correlation with catalogues or
surveys at other wavelengths (especially soft X-rays) is of invaluable support
in pinpointing the putative optical candidates, only accurate optical
spectroscopy can reveal the true nature of these sources. With the aim of
identifying them, we started in 2004 an optical spectroscopy program which uses
data from several telescopes worldwide and which proved extremely successful,
leading to the identification of about 200 INTEGRAL objects and nearly 130
Swift sources. Here we want to present a summary of this identification work
and an outlook of our preliminary results on identification of newly-discovered
sources belonging to the 4th IBIS catalog and to the 54 months Palermo
Swift/BAT catalog.


title:
On the Reflection Type Decomposition of the Adjoint Reduced Phase Space
  of a Compact Semisimple Lie group

abstract:
  We consider a system with symmetries whose configuration space is a compact
Lie group, acted upon by inner automorphisms. The classical reduced phase space
of this system decomposes into connected components of orbit type subsets. To
investigate hypothetical quantum effects of this decomposition one has to
construct the associated costratification of the Hilbert space of the quantum
system in the sense of Huebschmann. In the present paper, instead of the
decomposition by orbit types, we consider the related decomposition by
reflection types (conjugacy classes of reflection subgroups). These two
decompositions turn out to coincide e.g. for the classical groups SU(n) and
Sp(n). We derive defining relations for reflection type subsets in terms of
irreducible characters and discuss how to obtain from that the corresponding
costratification of the Hilbert space of the system. To illustrate the method,
we give explicit results for some low rank classical groups.


title:
Implications of a Froissart bound saturation of $\gamma^*$-$p$ deep
  inelastic scattering. Part I. Quark distributions at ultra small $x$

abstract:
  We argue that the deep inelastic structure function $F_2^{\gamma p}(x, Q^2)$,
regarded as a cross section for virtual $\gamma^*p$ scattering, is hadronic in
nature. This implies that its growth is limited by the Froissart bound at high
hadronic energies, giving a $\ln^2 (1/x)$ bound on $F_2^{\gamma p}$ as Bjorken
$x\rightarrow 0$. The same bound holds for the individual quark distributions.
In earlier work, we obtained a very accurate global fit to the combined HERA
data on $F_2^{\gamma p}$ using a fit function which respects the Froissart
bound at small $x$, and is equivalent in its $x$ dependence to the function
used successfully to describe all high energy hadronic cross sections,
including $\gamma p$ scattering. We extrapolate that fit by a factor of
$\lesssim$3 beyond the HERA region in the natural variable $\ln(1/x)$ to the
values of $x$ down to $x=10^{-14}$ and use the results to derive the quark
distributions needed for the reliable calculation of neutrino cross sections at
energies up to $E_\nu=10^{17}$ GeV. These distributions do not satisfy the
Feynman "wee parton" assumption, that they all converge toward a common
distribution $xq(x,Q^2)$ at small $x$ and large $Q^2$. This was used in some
past calculations to express the dominant neutrino structure function
$F_2^{\nu(\bar{\nu})}$ directly in terms of $F_2^{\gamma p}$. We show that the
correct distributions nevertheless give results for $F_2^{\nu(\bar{\nu})}$
which differ only slightly from those obtained assuming that the wee parton
limit holds. In two Appendices, we develop simple analytic results for the
effects of QCD evolution and operator-product corrections on the distribution
functions at small $x$, and show that these effects amount mainly to shifting
the values of $\ln(1/x)$ in the initial distributions.


title: An Optimal Pairs-Trading Rule

abstract:
  This paper is concerned with a pairs trading rule. The idea is to monitor two
historically correlated securities. When divergence is underway, i.e., one
stock moves up while the other moves down, a pairs trade is entered which
consists of a pair to short the outperforming stock and to long the
underperforming one. Such a strategy bets the "spread" between the two would
eventually converge. In this paper, a difference of the pair is governed by a
mean-reverting model. The objective is to trade the pair so as to maximize an
overall return. A fixed commission cost is charged with each transaction. In
addition, a stop-loss limit is imposed as a state constraint. The associated
HJB equations (quasi-variational inequalities) are used to characterize the
value functions. It is shown that the solution to the optimal stopping problem
can be obtained by solving a number of quasi-algebraic equations. We provide a
set of sufficient conditions in terms of a verification theorem. Numerical
examples are reported to demonstrate the results.


title: Continued fractions on the Heisenberg group

abstract:
  We provide a generalization of continued fractions to the Heisenberg group.
We prove an explicit estimate on the rate of convergence of the infinite
continued fraction and several surprising analogs of classical formulas about
continued fractions. We then discuss dynamical properties of the associated
Gauss map, comparing them with base-$b$ expansions on the Heisenberg group and
continued fractions on the complex plane.


title: Ba & Eu Abundances in M15 giant stars

abstract:
  To investigate the Ba and Eu abundances for a sample of 63 giant stars in the
globular cluster M15. This is the largest sample of M15 giants stars for which
Ba abundances have been determined and, due to the target selection of the
original research programme, the Ba abundances are complete along the red giant
branch. Stellar parameters were taken from the previous key study and a
microturbulence-surface gravity relation was determined for precise measurement
of the Ba line at 6496.898 Angstroms, which has a high sensitivity to
microturbulence. Element abundances for Ba, La, Eu, Ca, Ni and Fe were
calculated using spectrum synthesis and equivalent widths techniques. A bimodal
distribution in Ba, Eu and La abundances was found within the sample. The low
Ba,Eu,La mode had mean abundances of <[Ba/H]>=-2.41+/-0.16,
<[Eu/H]>=-1.80+/-0.08 and <[La/H]>=-2.19+/-0.13 while the high Ba,Eu,La mode
had mean abundances of <[Ba/H]>=-2.00+/-0.16, <[Eu/H]>=-1.65+/-0.13 and
<[La/H]>=-1.95+/-0.11. Both modes are indicative of a pollution scenario
dominated by the r-process, hence contributions from explosive nucleosynthesis
of massive stars. There may be evidence of further enhancement by another heavy
element process and of potential anticorrelations in Na-O for both modes
indicating a complex formation and evolution history for M15.


title: Mitigating Timing Side Channel in Shared Schedulers

abstract:
  In this work, we study information leakage in timing side channels that arise
in the context of shared event schedulers. Consider two processes, one of them
an innocuous process (referred to as Alice) and the other a malicious one
(referred to as Bob), using a common scheduler to process their jobs. Based on
when his jobs get processed, Bob wishes to learn about the pattern (size and
timing) of jobs of Alice. Depending on the context, knowledge of this pattern
could have serious implications on Alice's privacy and security. For instance,
shared routers can reveal traffic patterns, shared memory access can reveal
cloud usage patterns, and suchlike. We present a formal framework to study the
information leakage in shared resource schedulers using the pattern estimation
error as a performance metric. The first-come-first-serve (FCFS) scheduling
policy and time-division-multiple-access (TDMA) are identified as two extreme
policies on the privacy metric, FCFS has the least, and TDMA has the highest.
However, on performance based metrics, such as throughput and delay, it is well
known that FCFS significantly outperforms TDMA. We then derive two parametrized
policies, accumulate and serve, and proportional TDMA, which take two different
approaches to offer a tunable trade-off between privacy and performance.


title: Anderson's orthogonality catastrophe

abstract:
  We give an upper bound on the modulus of the ground-state overlap of two
non-interacting fermionic quantum systems with $N$ particles in a large but
finite volume $L^d$ of $d$-dimensional Euclidean space. The underlying
one-particle Hamiltonians of the two systems are standard Schr\"odinger
operators that differ by a non-negative compactly supported scalar potential.
In the thermodynamic limit, the bound exhibits an asymptotic power-law decay in
the system size $L$, showing that the ground-state overlap vanishes for
macroscopic systems. The decay exponent can be interpreted in terms of the
total scattering cross section averaged over all incident directions. The
result confirms and generalises P. W. Anderson's informal computation [Phys.
Rev. Lett. 18, 1049--1051 (1967)].


title: Very Forward proton-proton interactions with the LHCf detector

abstract:
  The LHCf experiment has been designed to precisely measure very forward
neutral particle spectra produced in proton-proton collisions at LHC up to an
energy of 14 TeV in the center of mass system. These measurements are of
fundamental importance to calibrate the Monte Carlo models widely used in the
high energy cosmic ray (HECR) field, up to an equivalent laboratory energy of
the order of 1017 eV. In 2009-2010 the experiment has completed the p-p data
taking at sqrt{s} = 0.9 TeV and sqrt{s}=7 TeV and the detectors have later on
been removed from the tunnel region, when the LHC luminosity increased above
1030 cm-2s-1. In this paper the most up-to-date results on the inclusive photon
spectra and the pi0 spectra measured by LHCf are reported. Comparison of these
spectra with the model expectations and the impact on high energy cosmic ray
(HECR) Physics are discussed. In addition, perspectives for future analyses as
well as the program for the next data taking period, in particular the foreseen
data taking in p-Pb collisions, will be discussed.


title: Interacting Non-equilibrium Systems with Two Temperatures

abstract:
  We investigate a simplified model of two fully connected magnetic systems
maintained at different temperatures by virtue of being connected to two
independent thermal baths while simultaneously being inter-connected with each
other. Using generating functional analysis, commonly used in statistical
mechanics, we find exactly soluble expressions for their individual
magnetisations that define a two-dimensional non-linear map, the equations of
which have the same form as those obtained for densely connected equilibrium
systems. Steady states correspond to the fixed points of this map, separating
the parameter space into a rich set of non-equilibrium phases that we analyse
in asymptotically high and low (non-equilibrium) temperature limits. The
theoretical formalism is shown to subvert to the classical non-equilibrium
steady state problem for two interacting systems with a non-zero heat transfer
between them that catalyses a phase transition between ambient non-equilibrium
states.


title:
Implications of a Froissart bound saturation of $\gamma^*$-$p$ deep
  inelastic scattering. Part II. Ultra-high energy neutrino interactions

abstract:
  In Part I (in this journal) we argued that the structure function
$F_2^{\gamma p}(x,Q^2)$ in deep inelastic $ep$ scattering, regarded as a cross
section for virtual $\gamma^*p$ scattering, has a saturated Froissart-bounded
form behaving as $\ln^2 (1/x)$ at small $x$. This form provides an excellent
fit to the low $x$ HERA data, including the very low $Q^2$ regions, and can be
extrapolated reliably to small $x$ using the natural variable $\ln(1/x)$. We
used our fit to derive quark distributions for values of $x$ down to
$x=10^{-14}$. We use those distributions here to evaluate ultra-high energy
(UHE) cross sections for neutrino scattering on an isoscalar nucleon,
$N=(n+p)/2$, up to laboratory neutrino energies $E_\nu \sim 10^{16}$-$10^{17}$
GeV where there are now limits on neutrino fluxes. We estimate that these cross
sections are accurate to $\sim$2% at the highest energies considered, with the
major uncertainty coming from the errors in the parameters that were needed to
fit $F_2^{\gamma p}(x,Q^2)$. We compare our results to recently published
neutrino cross sections derived from NLO parton distribution functions, which
become much larger at high energies because of the use of power-law
extrapolations of quark distributions to small $x$. We argue that our
calculation of the UHE $\nu N$ cross sections is the best one can make based
the existing experimental deep inelastic scattering data. Further, we show that
the strong interaction Froissart bound of $\ln^2 (1/x)$ on $F_2^{\gamma p}$
translates to an exact bound of $\ln^3E_\nu$ for leading-order-weak $\nu N$
scattering. The energy dependence of $\nu N$ total cross section measurements
consequently has important implications for hadronic interactions at enormous
cms (center-of-mass) energies not otherwise accessible.


title: Phase Diagram for Magnon Condensate in Yttrium Iron Garnet Film

abstract:
  Recently, magnons, which are quasiparticles describing the collective motion
of spins, were found to undergo Bose-Einstein condensation (BEC) at room
temperature in films of Yttrium Iron Garnet (YIG). Unlike other quasiparticle
BEC systems, this system has a spectrum with two degenerate minima, which makes
it possible for the system to have two condensates in momentum space. Recent
Brillouin Light scattering studies for a microwave-pumped YIG film of thickness
d=5 $\mu$m and field H=1 kOe find a low-contrast interference pattern at the
characteristic wavevector $Q$ of the magnon energy minimum. In this report, we
show that this modulation pattern can be quantitatively explained as due to
non-symmetric but coherent Bose-Einstein condensation of magnons into the two
energy minima. Our theory predicts a transition from a high-contrast symmetric
phase to a low-contrast non-symmetric phase on varying the $d$ and $H$, and a
new type of collective oscillations.


title: Modified melting crystal model and Ablowitz-Ladik hierarchy

abstract:
  This paper addresses the issue of integrable structure in a modified melting
crystal model of topological string theory on the resolved conifold. The
partition function can be expressed as the vacuum expectation value of an
operator on the Fock space of 2D complex free fermion fields. The quantum torus
algebra of fermion bilinears behind this expression is shown to have an
extended set of "shift symmetries". They are used to prove that the partition
function (deformed by external potentials) is essentially a tau function of the
2D Toda hierarchy. This special solution of the 2D Toda hierarchy can be
characterized by a factorization problem of $\ZZ\times\ZZ$ matrices as well.
The associated Lax operators turn out to be quotients of first order difference
operators. This implies that the solution of the 2D Toda hierarchy in question
is actually a solution of the Ablowitz-Ladik (equivalently, relativistic Toda)
hierarchy. As a byproduct, the shift symmetries are shown to be related to
matrix-valued quantum dilogarithmic functions.


title: Obstructing finite surgery

abstract:
  For a fixed p, there are only finitely many elliptic 3-manifolds given by
p/q-surgery on a knot in S^3. We prove this result by using the Heegaard Floer
correction terms (d-invariants) to obstruct elliptic manifolds from arising as
knot surgery.


title: Note on group distance magic complete bipartite graphs

abstract:
  A $\Gamma$-distance magic labeling of a graph $G=(V,E)$ with $|V | = n$ is a
bijection $\ell$ from $V$ to an Abelian group $\Gamma$ of order $n$ such that
the weight $w(x)=\sum_{y\in N_G(x)}\ell(y)$ of every vertex $x \in V$ is equal
to the same element $\mu \in \Gamma$, called the \emph{magic constant}. A graph
$G$ is called a \emph{group distance magic graph} if there exists a $\Gamma
$-distance magic labeling for every Abelian group $\Gamma$ of order $|V(G)|$.
  In this paper we prove that some complete $k$-partite graphs are
$\mathbb{Z}_p$-distance magic. Moreover we prove that $K_{m,n}$ is a group
distance magic if and only if $n+m \not \equiv 2 \pmod 4$. We also show that if
$n+m \equiv 2 \pmod 4$, then there does not exist a group $\Gamma$ of order
$n+m$ such that there exists a $\Gamma$-distance labeling for $K_{m,n}$.


title:
Topological Edge States and Fractional Quantum Hall Effect from Umklapp
  Scattering

abstract:
  We study anisotropic lattice strips in the presence of a magnetic field in
the quantum Hall effect regime. At specific magnetic fields, causing resonant
Umklapp scattering, the system is gapped in the bulk and supports chiral edge
states in close analogy to topological insulators. These gaps result in
plateaus for the Hall conductivity exactly at the known fillings n/m (both
positive integers and m odd) for the integer and fractional quantum Hall
effect. For double strips we find topological phase transitions with phases
that support midgap edge states with flat dispersion. The topological effects
predicted here could be tested directly in optical lattices.


title: RGE behaviour of U(2)^3 symmetry in SUSY

abstract:
  From the naturalness point of view, the first LHC results seem to disfavour
any constrained MSSM realization with universal conditions at the SUSY-breaking
scale. A more motivated scenario is given by split-family SUSY, in which the
first two generations of squarks are heavy, compatible with a U(2)^3 flavour
symmetry. Here, after reviewing the flavour structures obtained in this
framework, we consider the flavour symmetry to be broken at a very high scale,
and study the consequences at low energies through its RGE evolution. Initial
conditions compatible with a split scenario are found, and the preservation of
correlations from minimal U(2)^3 breaking are checked.


title: Bell violation for unknown continuous-variable states

abstract:
  We describe a new Bell test for two-particle entangled systems that engages
an unbounded continuous variable. The continuous variable state is allowed to
be arbitrary and inaccessible to direct measurements. A systematic method is
introduced to perform the required measurements indirectly. Our results provide
new perspectives on both the study of local realistic theory for
continuous-variable systems and on the nonlocal control theory of quantum
information.


title: A CHARA Array Survey of Circumstellar Disks around Nearby Be-type Stars

abstract:
  We report on a high angular resolution survey of circumstellar disks around
24 northern sky Be stars. The K-band continuum survey was made using the CHARA
Array long baseline interferometer (baselines of 30 to 331 m). The
interferometric visibilities were corrected for the flux contribution of
stellar companions in those cases where the Be star is a member of a known
binary or multiple system. For those targets with good uv coverage, we used a
four parameter Gaussian elliptical disk model to fit the visibilities and to
determine the axial ratio, position angle, K-band photospheric flux
contribution, and angular diameter of the disk major axis. For the other
targets with relatively limited uv coverage, we constrained the axial ratio,
inclination angle, and or disk position angle where necessary in order to
resolve the degeneracy between possible model solutions. We also made fits of
the ultraviolet and infrared spectral energy distributions to estimate the
stellar angular diameter and infrared flux excess of each target. The mean
ratio of the disk diameter (measured in K-band emission) to stellar diameter
(from SED modeling) is 4.4 among the 14 cases where we reliably resolved the
disk emission, a value which is generally lower than the disk size ratio
measured in the higher opacity Halpha emission line. We estimated the
equatorial rotational velocity from the projected rotational velocity and disk
inclination for 12 stars, and most of these stars rotate close to or at the
critical rotational velocity.


title: How Hidden Orders Generate Gaps in 1D Fermionic Systems

abstract:
  We demonstrate that hidden long range order is always present in the gapped
phases of interacting fermionic systems on one dimensional lattices. It is
captured by correlation functions of appropriate nonlocal charge and/or spin
operators, which remain asymptotically finite. The corresponding microscopic
orders are classified. The results are confirmed by DMRG numerical simulation
of the phase diagram of the extended Hubbard model, and of a Haldane insulator
phase.


title:
Velocity renormalization of nodal quasiparticles in d-wave
  superconductors

abstract:
  Gapless nodal quasiparticles emerge at a low-energy regime of high-$T_c$
cuprate superconductors due to the $d_{x^2 - y^2}$ gap symmetry. We study the
unusual renormalizations of the Fermi velocity $v_F$ and gap velocity
$v_{\Delta}$ of these quasiparticles close to various quantum critical points
in a superconducting dome. Special attention is paid to the behavior of the
velocity ratio, $v_{\Delta}/v_F$, since it determines a number of observable
quantities. We perform a renormalization-group analysis and show that the
velocity ratio may vanish, approach unity, or diverge at different quantum
critical points. The corresponding superfluid densities and critical
temperatures are suppressed, slightly increased, or significantly enhanced. The
effects of three types of static disorders, namely, random mass, random gauge
potential, and random chemical potential, on the stability of the system are
also addressed. An analogous analysis reveals that both random mass and random
gauge potential are irrelevant. This implies that these fixed points of the
velocity ratio are stable, and hence observable effects ignited by them are
unchanged. However, the random chemical potential is marginal. As a result,
these fixed points are broken, and thus, the instabilities of quantum phase
transitions are triggered.


title:
Direct imaging of hot spots in Bi_{2}Sr_{2}CaCu_{2}O_{8+\delta} mesa
  terahertz sources

abstract:
  Stacks of intrinsic Josephson junctions (IJJs) made from high-temperature
superconductors such as Bi_{2}Sr_{2}CaCu_{2}O_{8+\delta} (Bi-2212) are a
promising source of coherent continuous-wave terahertz radiation. It is thought
that at electrical bias conditions under which THz-emission occurs hot spots
may form due to resistive self-heating, and that these spots may be highly
beneficial for the generation of high levels of THz power. Here we perform an
imaging study of the temperature distribution at the surface of BSCCO stacks
utilizing the temperature-dependent 612nm fluorescence line of Eu^{3+} in a
europium chelate. The images directly reveal a highly non-uniform temperature
distribution in which the temperature in the middle of the stack can exceed the
superconducting transition temperature by tens of Kelvin under biasing
conditions typical for THz-emission.


title: Field Fluctuations in a One-Dimensional Cavity with a Mobile Wall

abstract:
  We consider a scalar field in a one-dimensional cavity with a mobile wall.
The wall is assumed bounded by a harmonic potential and its mechanical degrees
of freedom are treated quantum mechanically. The possible motion of the wall
makes the cavity length variable, and yields a wall-field interaction and an
effective interaction among the modes of the cavity. We consider the ground
state of the coupled system and calculate the average number of virtual
excitations of the cavity modes induced by the wall-field interaction, as well
as the average value of the field energy density. We compare our results with
analogous quantities for a cavity with fixed walls, and show a correction to
the Casimir potential energy between the cavity walls. We also find a change of
the field energy density in the cavity, particularly relevant in the proximity
of the mobile wall, yielding a correction to the Casimir-Polder interaction
with a polarizable body placed inside the cavity. Similarities and differences
of our results with the dynamical Casimir effect are also discussed.


title:
Discovery of very high energy gamma-ray emission from the blazar 1ES
  1727+502 with the MAGIC Telescopes

abstract:
  Motivated by the Costamante & Ghisellini (2002) predictions we investigated
if the blazar 1ES 1727+502 (z=0.055) is emitting very high energy (VHE, E>100
GeV) gamma rays. We observed the BL Lac object 1ES 1727+502 in stereoscopic
mode with the two MAGIC telescopes during 14 nights between May 6th and June
10th 2011, for a total effective observing time of 12.6 hours. For the study of
the multiwavelength spectral energy distribution (SED) we use simultaneous
optical R-band data from the KVA telescope, archival UV/optical and X-ray
observations by instruments UVOT and XRT on board of the Swift satellite and
high energy (HE, 0.1 GeV - 100 GeV) gamma-ray data from the Fermi-LAT
instrument. We detect, for the first time, VHE gamma-ray emission from 1ES
1727+502 at a statistical significance of 5.5 sigma. The integral flux above
150 GeV is estimated to be (2.1\pm0.4)% of the Crab Nebula flux and the
de-absorbed VHE spectrum has a photon index of (2.7\pm0.5). No significant
short-term variability was found in any of the wavebands presented here. We
model the SED using a one-zone synchrotron self-Compton model obtaining
parameters typical for this class of sources.


title: Negative Entropy and Black Hole Information

abstract:
  Based on negative entropy in entanglement, it is shown that a single-system
Copenhagen measurement protocol is equivalent to the two-system von Neumann
scheme with the memory filling up the system with negative information similar
to the Dirac sea of negative energy. After equating the two quantum measurement
protocols, we then apply this equivalence to the black hole radiation. That is,
the black hole evaporation corresponds to the quantum measurement process and
the two evaporation approaches, the observable-based single-system and the
two-system entanglement-based protocols, can be made equivalent using quantum
memory. In particular, the measurement choice, \theta, with the memory state
inside the horizon in the entanglement-based scheme is shown to correspond to
the observable of the measurement choice, \theta, outside the horizon in the
single-system protocol, that is, O_{\theta}^{out} = Q_{\theta}^{in}. This
indicates that the black hole as quantum memory is filling up with negative
information outside the horizon, and its entropy corresponds to the logarithm
of a number of equally probable measurement choices. This shows that the black
hole radiation is no different than ordinary quantum theory.


title:
The Dunkl oscillator in the plane II : representations of the symmetry
  algebra

abstract:
  The superintegrability, wavefunctions and overlap coefficients of the Dunkl
oscillator model in the plane were considered in the first part. Here
finite-dimensional representations of the symmetry algebra of the system,
called the Schwinger-Dunkl algebra sd(2), are investigated. The algebra sd(2)
has six generators, including two involutions and a central element, and can be
seen as a deformation of the Lie algebra u(2). Two of the symmetry generators,
J_3 and J_2, are respectively associated to the separation of variables in
Cartesian and polar coordinates. Using the parabosonic creation/annihilation
operators, two bases for the representations of sd(2), the Cartesian and
circular bases, are constructed. In the Cartesian basis, the operator J_3 is
diagonal and the operator J_2 acts in a tridiagonal fashion. In the circular
basis, the operator J_2 is block upper-triangular with all blocks 2x2 and the
operator J_3 acts in a tridiagonal fashion. The expansion coefficients between
the two bases are given by the Krawtchouk polynomials. In the general case, the
eigenvectors of J_2 in the circular basis are generated by the Heun polynomials
and their components are expressed in terms of the para-Krawtchouk polynomials.
In the fully isotropic case, the eigenvectors of J_2 are generated by little -1
Jacobi or ordinary Jacobi polynomials. The basis in which the operator J_2 is
diagonal is then considered. In this basis, the defining relations of the
Schwinger-Dunkl algebra imply that J_3 acts in a block tridiagonal fashion with
all blocks 2x2. The matrix elements of J_3 in this basis are given explicitly.


title: Local P-shtukas and their relation to global G-shtukas

abstract:
  This is the first in a sequence of two articles investigating moduli stacks
of global G-shtukas, which are function field analogs for Shimura varieties.
Here G is a flat affine group scheme of finite type over a smooth projective
curve, and global G-shtukas are generalizations of Drinfeld shtukas and analogs
of abelian varieties with additional structure. Our moduli stacks generalize
various moduli spaces used by different authors to prove instances of the
Langlands program over function fields.
  In the present article we explain the relation between global G-shtukas and
local P-shtukas, which are the function field analogs of p-divisible groups
with additional structure. We prove the analog of a theorem of Serre and Tate
stating the equivalence between the deformations of a global G-shtuka and its
associated local P-shtukas. We also investigate local P-shtukas alone and
explain their relation with Galois representations through their Tate modules.
And if P is a smooth affine group scheme with connected reductive generic fiber
we prove the existence of Rapoport--Zink spaces for bounded local P-shtukas as
formal schemes locally formally of finite type. In the sequel to this article
we use these Rapoport--Zink spaces to uniformize the moduli stacks of global
G-shtukas.


title: On Fields of rationality for automorphic representations

abstract:
  This paper proves two results on the field of rationality $\Q(\pi)$ for an
automorphic representation $\pi$, which is the subfield of $\C$ fixed under the
subgroup of $\Aut(\C)$ stabilizing the isomorphism class of the finite part of
$\pi$. For general linear groups and classical groups, our first main result is
the finiteness of the set of discrete automorphic representations $\pi$ such
that $\pi$ is unramified away from a fixed finite set of places, $\pi_\infty$
has a fixed infinitesimal character, and $[\Q(\pi):\Q]$ is bounded. The second
main result is that for classical groups, $[\Q(\pi):\Q]$ grows to infinity in a
family of automorphic representations in level aspect whose infinite components
are discrete series in a fixed $L$-packet under mild conditions.


title: Oscillations in turbulence-condensate system

abstract:
  We consider developed turbulence in the Gross-Pitaevsky model where
condensate appears due to an inverse cascade. Despite being fully turbulent,
the system demonstrates non-decaying periodic oscillations around a steady
state, when turbulence and condensate periodically exchange a small fraction of
waves. We show that these collective oscillations are not of a predator-prey
type, as was suggested earlier; they are due to phase coherence and anomalous
correlations imposed by the condensate.

categories: nlin.CD cond-mat.stat-mech nlin.AO nlin.PS


title:
Comment on "Correlated electron-nuclear dynamics: Exact factorization of
  the molecular wavefunction" [J. Chem. Phys. 137, 22A530 (2012)]

abstract:
  In spite of the relevance of the proposal introduced in the recent work A.
Abedi, N. T. Maitra and E. K. U. Gross, J. Chem. Phys. 137, 22A530, 2012, there
is an important ingredient which is missing. Namely, the proof that the norms
of the electronic and nuclear wavefunctions which are the solutions to the
nonlinear equations of motion are preserved by the evolution. To prove the
conservation of these norms is precisely the objective of this Comment.


title: Mobility of nonlocal solitons in fading optical lattices

abstract:
  We study the soliton mobility in nonlocal nonlinear media with an imprinted
fading optical lattice. The results show that the transverse mobility of
solitons varies with the lattice decay rate and the nonlocality degree, which
provides an opportunity for all-optical control of light.


title: Strong Coupling to Two-Dimensional Anderson Localized Modes

abstract:
  We use a scattering formalism to derive a condition of strong coupling
between a resonant scatterer and an Anderson localized mode for electromagnetic
waves in two dimensions. The strong coupling regime is demonstrated based on
exact numerical simulations, in perfect agreement with theory. The strong
coupling threshold can be expressed in terms of the Thouless conductance and
the Purcell factor, thus connecting key concepts in transport theory and cavity
quantum electrodynamics.


title:
Work in Progress: Enabling robot device discovery through robot device
  descriptions

abstract:
  There is no dearth of new robots that provide both generalized and customized
platforms for learning and research. Unfortunately as we attempt to adapt
existing software components, we are faced with an explosion of device drivers
that interface each hardware platform with existing frameworks. We certainly
gain the efficiencies of reusing algorithms and tools developed across
platforms but only once the device driver is created.
  We propose a domain specific language that describes the development and
runtime interface of a robot and defines its link to existing frameworks. The
Robot Device Interface Specification (RDIS) takes advantage of the internal
firmware present on many existing devices by defining the communication
mechanism, syntax and semantics in such a way to enable the generation of
automatic interface links and resource discovery. We present the current domain
model as it relates to differential drive robots as a mechanism to use the RDIS
to link described robots to HTML5 via web sockets and ROS (Robot Operating
System).


title: Gelfand Models for Diagram Algebras

abstract:
  A Gelfand model for a semisimple algebra A over C is a complex linear
representation that contains each irreducible representation of A with
multiplicity exactly one. We give a method of constructing these models that
works uniformly for a large class of semisimple, combinatorial diagram algebras
including: the partition, Brauer, rook monoid, rook-Brauer, Temperley-Lieb,
Motzkin, and planar rook monoid algebras. In each case, the model
representation is given by diagrams acting via "signed conjugation" on the
linear span of their vertically symmetric diagrams. This representation is a
generalization of the Saxl model for the symmetric group, and, in fact, our
method is to use the Jones basic construction to lift the Saxl model from the
symmetric group to each diagram algebra. In the case of the planar diagram
algebras, our construction exactly produces the irreducible representations of
the algebra.


title: Counting imaginary quadratic points via universal torsors

abstract:
  A conjecture of Manin predicts the distribution of rational points on Fano
varieties. We provide a framework for proofs of Manin's conjecture for del
Pezzo surfaces over imaginary quadratic fields, using universal torsors. Some
of our tools are formulated over arbitrary number fields.
  As an application, we prove Manin's conjecture over imaginary quadratic
fields K for the quartic del Pezzo surface S of singularity type A_3 with five
lines given in P^4 by the equations vw - xy = vy + wy + xz = 0.


title: Coexistence of Scale-Invariant States in Incompressible Elastomers

abstract:
  Cavitation and sulcification of soft elastomers are two examples of
thresholdless, nonlinear instabilities that evade detection by linearization. I
show that the onset of such instabilities can be understood as a kind of phase
coexistence between multiple scale-invariant states, and I constructively
enumerate the possible scale-invariant states of incompressible rubber in two
dimensions. Whereas true phases (like the affine deformations of rubber) are
homogeneous, the alternatives are inhomogeneous. In terms of the thermodynamics
of solids, both classes of states must generally be given equal consideration.

categories: cond-mat.soft cond-mat.mtrl-sci cond-mat.stat-mech math.AP


title: Neutron Imaging by Boric Acid

abstract:
  In this paper a new type of passive neutron detector based on the already
existing one, CR39, is described. Its operation was verified by three different
neutron sources: an Americium-Beryllium (Am241-Be) source; a TRIGA type nuclear
reactor; and a fast neutron reactor called TAPIRO. The obtained results,
reported here, positively confirm its operation and the accountability of the
new developed detecting technique.


title: Upper Bounds on the Size of Grain-Correcting Codes

abstract:
  In this paper, we re-visit the combinatorial error model of Mazumdar et al.
that models errors in high-density magnetic recording caused by lack of
knowledge of grain boundaries in the recording medium. We present new upper
bounds on the cardinality/rate of binary block codes that correct errors within
this model.


title:
Electrodynamics of the Superconducting State in Ultra-Thin Films at THz
  Frequencies

abstract:
  We report on terahertz frequency-domain spectroscopy (THz-FDS) experiments in
which we measure charge carrier dynamics and excitations of thin-film
superconducting systems at low temperatures in the THz spectral range. The
characteristics of the set-up and the experimental procedures are described
comprehensively. We discuss the single-particle density of states and a theory
of electrodynamic absorption and optical conductivity of conventional
superconductors. We present the experimental performance of the setup at low
temperatures for a broad spectral range from 0.1 - 1.1 THz by the example of
ultra-thin films of weakly disordered superconductors niobium nitride (NbN) and
tantalum nitride (TaN) with different values of critical temperatures.
Furthermore, we analyze and interpret our experimental data within the
framework of conventional Bardeen-Cooper-Schrieffer (BCS) theory of
superconductivity.


title: Scalable Routing on Flat Names

abstract:
  We introduce a protocol which routes on flat, location-independent
identifiers with guaranteed scalability and low stretch. Our design builds on
theoretical advances in the area of compact routing, and is the first to
realize these guarantees in a dynamic distributed setting.


title: Minimization of ion micromotion using ultracold atomic probes

abstract:
  We report on a new sensitive method to minimize excess micromotion of an ion
in a Paul trap. The ion is placed in an ultracold cloud of neutral Rb atoms in
which ionic micromotion induces atomic losses and heating. Micromotion is
minimized by applying static electric offset fields such that both loss and
heating are minimized. We achieve a compensation precision as high as the best
compensation methods to date. In contrast to these methods, our scheme is
applicable even for ions that cannot be optically probed. Furthermore, our
method avoids the formation of temporary patch charges which are a main issue
for the long-term stability of micromotion minimization.


title: Non-equilibrium quasi-condensates in reduced dimensions

abstract:
  We develop a generic phenomenological model to describe the fluctuations on
top of a non-equilibrium Bose-Einstein condensate. Analytic expressions are
obtained for the momentum distribution of the non-condensed cloud and for the
long-distance behavior of the spatial coherence in the different
dimensionalities. Comparison of our predictions with available experimental
data on condensates of exciton-polaritons and on surface-emitting planar laser
devices is finally made.


title: Is a rational explanation of wave-particle duality possible?

abstract:
  Wave-particle duality is one of the fundamental properties of matter and at
the same time, one of the mysteries of modern physics. In this paper, we
propose and analyze a new interpretation of the wave-particle duality, and
propose a new rule that relates the corpuscular and wave properties of quantum
particles, and replaces the Born's rule. We introduce a new representation
about quantum particles as temporary objects that are born permanently in a
wave field and spontaneously decayed due to their "instability". Thus, we fill
with the physical meaning the standard notions of "creation" and "annihilation"
of the particles, used in the second quantization formalism. We show that the
traditional probabilistic interpretation of quantum mechanics in the form of
the Born's rule is an approximate consequence of the proposed theory. The
proposed theory allows explaining the indistinguishability of quantum particles
and shows meaninglessness of the concept of their trajectories. We give an
explanation of the Heisenberg uncertainty principle within the limits of this
theory in terms of classical physics that allows us to return to an objective
understanding of the measurement process and do not consider it as a compulsory
part of the physical process.


title: Stability properties and topology at infinity of f-minimal hypersurfaces

abstract:
  We study stability properties of $f$-minimal hypersurfaces isometrically
immersed in weighted manifolds with non-negative Bakry-Emery Ricci curvature
under volume growth conditions. Moreover, exploiting a weighted version of a
finiteness result and the adaptation to this setting of Li-Tam theory, we
investigate the topology at infinity of $f$-minimal hypersurfaces. On the way,
we prove a new comparison result in weighted geometry and we provide a general
weighted $L^1$-Sobolev inequality for hypersurfaces in Cartan-Hadamard weighted
manifolds, satisfying suitable restrictions on the weight function.


title: Comparing measures of association in 2x2 probability tables

abstract:
  Measures of association play a role in selecting 2x2 tables exhibiting strong
dependence in high-dimensional binary data. Several measures are in use
differing on specific tables and in their dependence on the margins.
  We study a 2-dimensional group of margin transformations on the 3-dimensional
manifold T of all 2x2 probability tables. The margin transformations allow
introducing natural coordinates that identify T with the real 3-space such that
the x-axis corresponds to log(sqrt(odds-ratio)) and margins vary on planes
x=const. We use these coordinates to visualise and compare measures of
association with respect to their dependence on the margins given the
odds-ratio, their limit behaviour when cells approach zero and their weighting
properties.
  We propose a novel measure of association in which tables with single small
entries are up-weighted but those with skewed margins are down-weighted
according to the relative entropy among the tables of the same odds-ratio.


title: Scalar Supersymmetry in Bi-Spinor Gauge Theory

abstract:
  We describe a new realization of both global and local supersymmetry acting
in spaces of commuting and anticommuting differential forms. Unlike the
standard supersymmetry, it has Lorentz scalar transformation parameters. It is
related but is not reducible to standard supersymmetry. Reformulation of the
Standard Model with the new supersymmetry, called scalar supersymmetry, can be
achieved with the particle content of the SM. BRST symmetry is extended to
include scalar supersymmetry multiplets. Linear realization of scalar
supersymmetry with free fields or with fields interacting with background
gravity is described. Gauge interactions require non-linear realizations of
scalar supersymmetry and, except for SU(2), non-linear gauge-fixing conditions.
Requiring scalar supersymmetry of interacting action with the simplest chiral
multiplet can reduce the dynamical content of the theory to that of the SM: one
complex scalar, gauge fields, and three generations of Weyl spinors. At low
energies scalar supersymmetry is explicitly broken by gauge interactions.
However, in the asymptotically free case it becomes exact in the ultraviolet
limit. Thus it has the two most desirable features of softly broken standard
supersymmetry built in. Implementation of exact scalar supersymmetry in an
interacting string action is given.


title:
Quantized magnetic flux through the orbits of hydrogen-like atoms within
  the atomic model of Sommerfeld

abstract:
  Within the Sommerfeld atomic model the quantization of magnetic flux through
the electronic orbits is investigated together with its dependency on
additional sources of magnetic fields. These sources alter the magnetic flux
through the atomic orbits and in consequence are causing energy shifts. This
effect is investigated for the cases, where the source is an external magnetic
field, the magnetic moment of the nucleus or the magnetic moment of the
electron. The energy shifts due to external magnetic fields, the magnetic
dipole contribution of the hyperfine splitting and the spin-orbit coupling can
be reproduced very well. The meaning of 'spin', however, changes within this
approach drastically. The unusual Land\'e g-factor of 2 for the electron is a
result of the orbital motion and the magnetic moment of the electron rather
than it is an intrinsic property of the electron.


title: On the volume of the convex hull of two convex bodies

abstract:
  In this note we examine the volume of the convex hull of two congruent copies
of a convex body in Euclidean $n$-space, under some subsets of the isometry
group of the space. We prove inequalities for this volume if the two bodies are
translates, or reflected copies of each other about a common point or a
hyperplane containing it. In particular, we give a proof of a related
conjecture of Rogers and Shephard.


title: The quantum vacuum as the origin of the speed of light

abstract:
  We show that the vacuum permeability and permittivity may originate from the
magnetization and the polarization of continuously appearing and disappearing
fermion pairs. We then show that if we simply model the propagation of the
photon in vacuum as a series of transient captures within these ephemeral
pairs, we can derive a finite photon velocity. Requiring that this velocity is
equal to the speed of light constrains our model of vacuum. Within this
approach, the propagation of a photon is a statistical process at scales much
larger than the Planck scale. Therefore we expect its time of flight to
fluctuate. We propose an experimental test of this prediction.


title:
Effect of both Z and Z^prime - mediated flavor-changing neutral currents
  on $B_s$ decays into $tau^+tau^-$

abstract:
  In recent years, $B_s$ decays into $tau^+tau^-$ has attracted a lot of
attention since it is very sensitive to the structure of standard model (SM)
and potential source of new physics beyond SM. In this paper, we study the
effect of both Z and -mediated flavor-changing neutral currents on the $B_s$
decays into $tau^+tau^-$. We find the branching ratio of $B_s$ decays into
$tau^+tau^-$ is enhanced relative to SM prediction, which would help to explain
the recent observed CP-violation from like-sign dimuon charge asymmetry in the
B system.


title: A homological reformulation of the link condition

abstract:
  We prove an equivalent condition for the existence of a link between prime
ideals in terms of the structure of a certain cohomology module. We use this
formulation to answer an open question regarding the nature of module
extensions over one sided noetherian rings. We apply the techniques developed
in this paper to the local link structure of prime ideals of small homological
height and examine when certain noetherian rings satisfy the density condition.


title:
Solar wind test of the de Broglie-Proca's massive photon with Cluster
  multi-spacecraft data

abstract:
  Our understanding of the universe at large and small scales relies largely on
electromagnetic observations. As photons are the messengers, fundamental
physics has a concern in testing their properties, including the absence of
mass. We use Cluster four spacecraft data in the solar wind at 1 AU to estimate
the mass upper limit for the photon. We look for deviations from Amp\`ere's
law, through the curlometer technique for the computation of the magnetic
field, and through the measurements of ion and electron velocities for the
computation of the current. We show that the upper bound for $m_\gamma$ lies
between $1.4 \times 10^{-49}$ and $3.4 \times 10^{-51}$ kg, and thereby discuss
the currently accepted lower limits in the solar wind.

categories: hep-ph astro-ph.HE gr-qc physics.plasm-ph physics.space-ph


title: Lorentzian area measures and the Christoffel problem

abstract:
  We introduce a particular class of unbounded closed convex sets of
$\R^{d+1}$, called F-convex sets (F stands for future). To define them, we use
the Minkowski bilinear form of signature $(+,...,+,-)$ instead of the usual
scalar product, and we ask the Gauss map to be a surjection onto the hyperbolic
space $\H^d$. Important examples are embeddings of the universal cover of
so-called globally hyperbolic maximal flat Lorentzian manifolds.
  Basic tools are first derived, similarly to the classical study of convex
bodies. For example, F-convex sets are determined by their support function,
which is defined on $\H^d$. Then the area measures of order $i$, $0\leq i\leq
d$ are defined. As in the convex bodies case, they are the coefficients of the
polynomial in $\epsilon$ which is the volume of an $\epsilon$ approximation of
the convex set. Here the area measures are defined with respect to the
  Lorentzian structure.
  Then we focus on the area measure of order one. Finding necessary and
sufficient conditions for a measure (here on $\H^d$) to be the first area
measure of a F-convex set is the Christoffel Problem. We derive many results
about this problem. If we restrict to "Fuchsian" F-convex set (those who are
invariant under linear isometries acting cocompactly on $\H^d$), then the
problem is totally solved, analogously to the case of convex bodies. In this
case the measure can be given on a compact hyperbolic manifold.
  Particular attention is given on the smooth and polyhedral cases. In those
cases, the Christoffel problem is equivalent to prescribing the mean radius of
curvature and the edge lengths respectively.


title: On the unilateral shift as a Hilbert module over the disc algebra

abstract:
  We study the unilateral shift (of arbitrary countable multiplicity) as a
Hilbert module over the disc algebra and the associated extension groups. In
relation with the problem of determining whether this module is projective, we
consider a special class of extensions, which we call "polynomial". We show
that the subgroup of polynomial extensions of a contractive module by the
adjoint of the unilateral shift is trivial. The main tool is a function
theoretic decomposition of the Sz.-Nagy--Foias model space for completely
non-unitary contractions.


title: Characteristics of Plasma Turbulence in the Mega Amp Spherical Tokamak

abstract:
  Turbulence is a major factor limiting the achievement of better tokamak
performance as it enhances the transport of particles, momentum and heat which
hinders the foremost objective of tokamaks. Hence, understanding and possibly
being able to control turbulence in tokamaks is of paramount importance, not to
mention our intellectual curiosity of it.


title: On Sylvester Waves and restricted partitions

abstract:
  The higher Sylvester waves are discussed. Techniques used involve finite
difference operators. For example, using Herschel's theorem, elegant
expressions for Euler's rational functions and the Todd operator are found.
Derivative expansions are also rapidly treated by the same method.
  A general form for the wave is obtained using multiplicative series, and
comments made on its further reduction. As is known, Dedekind sums arise in the
case of coprime components and it is pointed out that Brioschi had this result,
but not the terminology, very early on. His proof is repeated.
  Adding a set of ones to the components of the denumerant corresponds to a
succession of (discrete) smoothings and is a Cesaro sum. Using a spectral
vocabulary, I take the opportunity to exhibit the finite difference
counterparts of some continuous, distributional properties of Riesz typical
means.


title: Robust Capon Beamforming via Shaping Beam Pattern

abstract:
  High sidelobe level and direction of arrival (DOA) estimation sensitivity are
two major disadvantages of the Capon beamforming. To deal with these problems,
this paper gives an overview of a series of robust Capon beamforming methods
via shaping beam pattern, including sparse Capon beamforming, weighted sparse
Capon beamforming, mixed norm based Capon beamforming, total variation
minimization based Capon beamforming, mainlobe-to-sidelobe power ratio
maximization based Capon beamforming. With these additional structure-inducing
constraints, the sidelobe is suppressed, and the robustness against DOA
mismatch is improved too. Simulations show that the obtained beamformers
outperform the standard Capon beamformer.


title: xPand: An algorithm for perturbing homogeneous cosmologies

abstract:
  In this paper, we develop in detail a fully geometrical method for deriving
perturbation equations about a spatially homogeneous background. This method
relies on the 3+1 splitting of the background space-time and does not use any
particular set of coordinates: it is implemented in terms of geometrical
quantities only, using the tensor algebra package xTensor in the xAct
distribution along with the extension for perturbations xPert. Our algorithm
allows one to obtain the perturbation equations for all types of homogeneous
cosmologies, up to any order and in all possible gauges. As applications, we
recover the well-known perturbed Einstein equations for
Friedmann-Lemaitre-Robertson-Walker cosmologies up to second order and for
Bianchi I cosmologies at first order. This work paves the way to the study of
these models at higher order and to that of any other perturbed Bianchi
cosmologies, by circumventing the usually too cumbersome derivation of the
perturbed equations.


title:
Low frequency resistance and critical current fluctuations in Al-based
  Josephson junctions

abstract:
  We present low-temperature measurements of the low-frequency $1/f$ noise
arising from an ensemble of two-level fluctuators in the oxide barrier of
Al/AlO$_{x}$/Al Josephson junctions. The fractional noise power spectrum of the
critical-current and normal-state resistance have similar magnitudes and scale
linearly with temperature, implying an equivalence between the two. Compiling
our results and published data, we deduce the area and temperature scaling of
the noise for AlO$_{x}$ barrier junctions. We find that the density of
two-level fluctuators in the junction barrier is similar to the typical value
in glassy systems. We discuss the implications and consistency with recent
qubit experiments.


title: Modelling unidirectional liquid spreading on slanted microposts

abstract:
  A lattice Boltzmann algorithm is used to simulate the slow spreading of drops
on a surface patterned with slanted micro-posts. Gibb's pinning of the
interface on the sides or top of the posts leads to unidirectional spreading
over a wide range of contact angles and inclination angles of the posts.
Regimes for spreading in no, one or two directions are identified, and shown to
agree well with a two-dimensional theory proposed in Chu, Xiao and Wang (Nature
Materials, 9, 413). A more detailed numerical analysis of the contact line
shapes allows us to understand deviations from the two dimensional model, and
to identify the shapes of the pinned interfaces.


title:
Gravity and magnetic field dependent study of diffraction patterns in
  ferrofluids

abstract:
  In this paper, we report the experimental observation of diffraction patterns
in a ferrofluid comprising of Fe3O4 nanoparticles in hexane by a 10 mW He-Ne
laser beam. An external dc magnetic field (0-2 kG) was applied perpendicular to
the beam. The diffraction pattern showed variation at different depths of the
sample in both zero and applied magnetic field. The patterns also exhibit a
change in shape and size as the external field is varied. This effect is
presumably arising due to thermally induced self-diffraction under the
influence of gravity and external magnetic field.


title:
Magnetotransport along a boundary: From coherent electron focusing to
  edge channel transport

abstract:
  We study theoretically how electrons, coherently injected at one point on the
boundary of a two-dimensional electron system, are focused by a perpendicular
magnetic field $B$ onto another point on the boundary. Using the
non-equilibrium Green's function approach, we calculate the generalized 4-point
Hall resistance $R_{xy}$ as a function of B. In weak fields, $R_{xy}$ shows the
characteristic equidistant peaks observed in the experiment and explained by
classical cyclotron motion along the boundary. In strong fields, $R_{xy}$ shows
a single extended plateau reflecting the quantum Hall effect. In intermediate
fields, we find superimposed upon the lower Hall plateaus anomalous
oscillations, which are neither periodic in 1/B (quantum Hall effect) nor in
$B$ (classical cyclotron motion). The oscillations are explained by the
interference between the occupied edge channels, which causes beatings in
$R_{xy}$. In the case of two occupied edge channels, these beatings constitute
a new commensurability between the magnetic flux enclosed within the edge
channels and the flux quantum. Introducing decoherence and a partially specular
boundary shows that this new effect is quite robust.


title:
Squeezing of light via reflection from a silicon micromechanical
  resonator

abstract:
  We present the measurement of squeezed light generation using an engineered
optomechanical system fabricated from a silicon microchip and composed of a
micromechanical resonator coupled to a nanophotonic cavity. Laser light is used
to measure the fluctuations in the position of the mechanical resonator at a
measurement rate comparable to the free dynamics of the mechanical resonator,
and greater than its thermal decoherence rate. By approaching the strong
continuous measurement regime we observe, through homodyne detection,
non-trivial modifications of the reflected light's vacuum fluctuation spectrum.
In spite of the mechanical resonator's highly excited thermal state ($10,000$
phonons), we observe squeezing at the level of $4.5 \pm 0.5%$ below that of
shot-noise over a few MHz bandwidth around the mechanical resonance frequency
of 28 MHz. This squeezing is interpreted as an unambiguous quantum signature of
radiation pressure shot-noise.


title: Some remarks on the semi-positivity theorems

abstract:
  We show that the dualizing sheaves of reduced simple normal crossings pairs
have a canonical weight filtration in a compatible way with the one on the
corresponding mixed Hodge modules by calculating the extension classes between
the dualizing sheaves of smooth varieties. Using the weight spectral sequence
of mixed Hodge modules, we then reduce the semi-positivity theorem for the
higher direct images of dualizing sheaves to the smooth case where the
assertion is well known. This may be used to simplify some constructions in a
recent paper of Y. Kawamata. We also give a simple proof of the semi-positivity
theorem for admissible variations of mixed Hodge structure in [FF] by using the
theories of Cattani, Kaplan, Schmid, Steenbrink, and Zucker. This generalizes
Kawamata's classical result in the pure case.


title: Gluon Propagators in Maximally Abelian Gauge in SU(3) Lattice QCD

abstract:
  In SU(3) lattice QCD, we study diagonal and off-diagonal gluon propagators in
the maximally Abelian (MA) gauge with U(1)$_3 \timesU(1)_8$ Landau gauge
fixing. These propagators are studied both in the coordinate space and in the
momentum space. The Monte Carlo simulation is performed on $16^4$ at
$\beta$=6.0 and $32^4$ at $\beta$=5.8 and 6.0 at the quenched level. In the
four-dimensional Euclidean space-time, the effective mass of diagonal gluons is
estimated as $M_{\mathrm{diag}} \simeq 0.3\mathrm{GeV}$ and that of
off-diagonal gluons as $M_{\mathrm{off}} \simeq 1\mathrm{GeV}$ in the region of
$r =0.4-1.0$fm. In the momentum space, the effective mass of diagonal gluons is
estimated as $M_{\mathrm{diag}} \simeq 0.3\mathrm{GeV}$ and that of
off-diagonal gluons as $M_{\mathrm{off}} \simeq 1\mathrm{GeV}$ in the region of
$p <1.1$GeV. The off-diagonal gluon propagator is relatively suppressed in the
infrared region and seems to be finite at zero momentum, while the diagonal
gluon propagator is enhanced. Furthermore, we also study the functional form of
these propagators in momentum space. These propagators are well fitted by
$Z/(p^2+m^2)^\nu$ with fit parameters, $Z, m$ and $\nu$ in the region of $p
<3.0$GeV. From the fit results and lattice calculations, all of the spectral
functions of diagonal and off-diagonal gluons would have negative regions.


title: Adaptive Hamiltonian and Riemann Manifold Monte Carlo Samplers

abstract:
  In this paper we address the widely-experienced difficulty in tuning
Hamiltonian-based Monte Carlo samplers. We develop an algorithm that allows for
the adaptation of Hamiltonian and Riemann manifold Hamiltonian Monte Carlo
samplers using Bayesian optimization that allows for infinite adaptation of the
parameters of these samplers. We show that the resulting sampling algorithms
are ergodic, and that the use of our adaptive algorithms makes it easy to
obtain more efficient samplers, in some cases precluding the need for more
complex solutions. Hamiltonian-based Monte Carlo samplers are widely known to
be an excellent choice of MCMC method, and we aim with this paper to remove a
key obstacle towards the more widespread use of these samplers in practice.


title: Threshold-Coloring and Unit-Cube Contact Representation of Graphs

abstract:
  In this paper we study threshold coloring of graphs, where the vertex colors
represented by integers are used to describe any spanning subgraph of the given
graph as follows. Pairs of vertices with near colors imply the edge between
them is present and pairs of vertices with far colors imply the edge is absent.
Not all planar graphs are threshold-colorable, but several subclasses, such as
trees, some planar grids, and planar graphs without short cycles can always be
threshold-colored. Using these results we obtain unit-cube contact
representation of several subclasses of planar graphs. Variants of the
threshold coloring problem are related to well-known graph coloring and other
graph-theoretic problems. Using these relations we show the NP-completeness for
two of these variants, and describe a polynomial-time algorithm for another.


title:
Jet-Hadron Correlations in sqrt{s_{NN}} = 200 GeV p+p and Central Au+Au
  Collisions

abstract:
  Azimuthal angular correlations of charged hadrons with respect to the axis of
a reconstructed (trigger) jet in Au+Au and p+p collisions at
$\sqrt{s_{\text{NN}}} = 200 \text{GeV}$ in STAR are presented. The trigger jet
population in Au+Au collisions is biased towards jets that have not interacted
with the medium, allowing easier matching of jet energies between Au+Au and p+p
collisions while enhancing medium effects on the recoil jet. The associated
hadron yield of the recoil jet is significantly suppressed at high transverse
momentum ($p_{\text{T}}^{\text{assoc}}$) and enhanced at low
$p_{\text{T}}^{\text{assoc}}$ in 0-20% central Au+Au collisions compared to p+p
collisions, which is indicative of medium-induced parton energy loss in
ultrarelativistic heavy-ion collisions.


title:
Quasinormal modes and thermodynamical aspects of the 3D Lifshitz black
  hole

abstract:
  We consider scalar and spinorial perturbations on a background described by a
$z=3$ three-dimensional Lifshitz black hole. We obtained the corresponding
quasinormal modes which perfectly agree with the analytical result for the
quasinormal frequency in the scalar case. The numerical results for the
spinorial perturbations reinforce our conclusion on the stability of the model
under these perturbations. We also calculate the area spectrum, which prove to
be equally spaced, as an application of our results.