title:
Stability of Numerical Methods for Jump Diffusions and Markovian
  Switching Jump Diffusions

abstract:
  This work focuses on stability analysis of numerical solutions to jump
diffusions and jump diffusions with Markovian switching. Due to the use of
Poisson processes, using asymptotic expansions as in the usual approach of
treating diffusion processes does not work. Different from the existing
treatments of Euler-Maurayama methods for solutions of stochastic differential
equations, we use techniques from stochastic approximation. We analyze the
almost sure exponential stability and exponential $p$-stability. The benchmark
test model in numerical solutions, namely, one-dimensional linear scalar jump
diffusion is examined first and easily verifiable conditions are presented.
Then Markovian regime-switching jump diffusions are dealt with. Moreover,
analysis on stability of numerical methods for linearizable and
multi-dimensional jump diffusions is carried out.


title: Failure of Logarithmic Oscillators to Thermostat Small Atomic Clusters

abstract:
  A logarithmic oscillator has the outstanding property that the expectation
value of its kinetic energy is constant for all stationary states [1]. Recently
the ansatz that this property can be used to define a Hamiltonian thermostat
has been put forward [2]. The latter publication suggests that the logarithmic
oscillator weakly coupled to a small system would serve as a thermostat as long
as few degrees of freedom are involved such as in atomic clusters. We have
applied these ideas to a cluster of four Lennard-Jones atoms and inspected two
different models of coupling between the cluster and the logarithmic oscillator
in 3D. In both cases we show that there is a clear generation of kinetic motion
of the cluster center of mass, but that kinetic energy due to interatomic
vibrations are not significantly affected by coupling to the logarithmic
oscillator. This is a failure of the published ansatz [2], as the logarithmic
oscillator is unable to modify the kinetic energy due to vibrations in small
atomic clusters.


title:
Marrying ab initio calculations and Halo EFT: the case of ${}^7{\rm Be}
  + p \rightarrow {}^8{\rm B} + \gamma$

abstract:
  We report a leading-order (LO) calculation of
$^7\mathrm{Be}(p,\gamma)^8\mathrm{B}$ in a low-energy effective field theory.
$^8\mathrm{B}$ is treated as a shallow proton$+^7\mathrm{Be}$ core and
proton$+^7\mathrm{Be}^{*}$ (core excitation) $p$-wave bound state. The
couplings are fixed using measured binding energies and proton-$^7\mathrm{Be}$
$s$-wave scattering lengths, together with $^8\mathrm{B}$ asymptotic
normalization coefficients from ab initio calculations. We obtain a zero-energy
$S$-factor of $18.2 \pm 1.2~({\rm ANC~only})$ eV b. Given that this is a LO
result it is consistent with the recommended value $S(0)=20.8\pm1.6$ eV b. Our
computed $S(E)$ compares favorably with experimental data on
$^7\mathrm{Be}(p,\gamma)^8\mathrm{B}$ for $E <0.4$ MeV. We emphasize the
important role of proton-$^7\mathrm{Be}$ scattering parameters in determining
the energy dependence of $S(E)$, and demonstrate that their present
uncertainties significantly limit attempts to extrapolate these data to stellar
energies.


title:
Observational Results of a Multi-Telescope Campaign in Search of
  Interstellar Urea [(NH$_2$)$_2$CO]

abstract:
  In this paper, we present the results of an observational search for gas
phase urea [(NH$_2$)$_2$CO] observed towards the Sgr B2(N-LMH) region. We show
data covering urea transitions from $\sim$100 GHz to 250 GHz from five
different observational facilities: BIMA, CARMA, the NRAO 12 m telescope, the
IRAM 30 m telescope, and SEST. The results show that the features ascribed to
urea can be reproduced across the entire observed bandwidth and all facilities
by best fit column density, temperature, and source size parameters which vary
by less than a factor of 2 between observations merely by adjusting for
telescope-specific parameters. Interferometric observations show that the
emission arising from these transitions is cospatial and compact, consistent
with the derived source sizes and emission from a single species. Despite this
evidence, the spectral complexity, both of (NH$_2$)$_2$CO and of Sgr B2(N),
makes the definitive identification of this molecule challenging. We present
observational spectra, laboratory data, and models, and discuss our results in
the context of a possible molecular detection of urea.


title: Constrained Codes for Rank Modulation

abstract:
  Motivated by the rank modulation scheme, a recent work by Sala and Dolecek
explored the study of constraint codes for permutations. The constraint studied
by them is inherited by the inter-cell interference phenomenon in flash
memories, where high-level cells can inadvertently increase the level of
low-level cells.
  In this paper, the model studied by Sala and Dolecek is extended into two
constraints. A permutation $\sigma \in S_n$ satisfies the \emph{two-neighbor
$k$-constraint} if for all $2 \leq i \leq n-1$ either
$|\sigma(i-1)-\sigma(i)|\leq k$ or $|\sigma(i)-\sigma(i+1)|\leq k$, and it
satisfies the \emph{asymmetric two-neighbor $k$-constraint} if for all $2 \leq
i \leq n-1$, either $\sigma(i-1)-\sigma(i) < k$ or $\sigma(i+1)-\sigma(i) < k$.
We show that the capacity of the first constraint is $(1+\epsilon)/2$ in case
that $k=\Theta(n^{\epsilon})$ and the capacity of the second constraint is 1
regardless to the value of $k$. We also extend our results and study the
capacity of these two constraints combined with error-correction codes in the
Kendall's $\tau$ metric.


title: Dynamical Heterogeneity in the Glassy State

abstract:
  We compare dynamical heterogeneities in equilibrated supercooled liquids and
in the nonequilibrium glassy state within the framework of the random first
order transition theory. Fluctuating mobility generation and transport in the
glass are treated by numerically solving stochastic continuum equations for
mobility and fictive temperature fields that arise from an extended mode
coupling theory containing activated events. Fluctuating spatiotemporal
structures in aging and rejuvenating glasses lead to dynamical heterogeneity in
glasses with characteristics distinct from those found in the equilibrium
supercooled liquid. The non-Gaussian distribution of activation free energies,
the stretching exponent $\beta$, and the growth of characteristic lengths are
studied along with the four-point correlation function. Asymmetric
thermodynamic responses upon heating and cooling are predicted to be the
results of the heterogeneity and the out-of-equilibrium behavior of glasses
below $T_g$. Numerical results agree with experimental calorimetry. We
numerically confirm the prediction of Lubchenko and Wolynes in the glass that
the dynamical heterogeneity can lead to noticeably bimodal distributions of
local fictive temperatures which explains in a unified way recent experimental
observations that have been interpreted as coming from two distinct
equilibration mechanisms in glasses.


title:
Magnified Views of the Ultrafast Outflow of the z = 1.51 AGN HS
  0810+2554

abstract:
  We present results from an observation of the gravitationally lensed z=1.51
narrow absorption line AGN HS 0810+2554 performed with the Chandra X-ray
Observatory. The factor of ~100 lensing magnification of HS 0810+2554 makes
this source exceptionally bright. Absorption lines are detected at rest-frame
energies of ~ 7.7 keV and ~11.0 keV at >97% significance. By interpreting these
lines to arise from highly ionized iron the implied outflow velocities of the
X-ray absorbing gas corresponding to these lines are 0.13c and 0.41c,
respectively. The presence of these relativistic outflows and the absence of
any significant low-energy X-ray absorption suggest that a shielding gas is not
required for the generation of the relativistic X-ray absorbing winds in HS
0810+2554. UV spectroscopic observations with VLT/UVES indicate that the UV
absorbing material is outflowing at v_UV ~0.065c. Our analysis indicates that
the fraction of the total bolometric energy released by HS 0810+2554 into the
IGM in the form of kinetic energy is epsilon_k = 1.0(-0.6,+0.8). An efficiency
of greater than unity implies that magnetic driving is likely a significant
contributor to the acceleration of this X-ray absorbing wind. We also estimate
the mass-outflow rate of the strongest absorption component to be
Mdot_abs=1.1(-0.7,+0.9) M_solar yr^-1. Assuming that the energetic outflow
detected in the NAL AGN HS 0810+2554 is a common property of most AGN it would
suggest that the X-ray absorbing wind may have a larger opening angle than
previously thought. This has important consequences for estimating the feedback
contribution of X-ray absorbing winds to the surrounding IGM.


title:
Ground states for scalar field equations with anisotropic nonlocal
  nonlinearities

abstract:
  We consider a class of scalar field equations with anisotropic nonlocal
nonlinearities. We obtain a suitable extension of the well-known compactness
lemma of Benci and Cerami to this variable exponent setting, and use it to
prove that the Palais-Smale condition holds at all level below a certain
threshold. We deduce the existence of a ground state when the variable exponent
slowly approaches the limit at infinity from below.


title:
Dimension of physical systems, information processing, and
  thermodynamics

abstract:
  We ask how quantum theory compares to more general physical theories from the
point of view of dimension. To do so, we first give two model independent
definition of the dimension of physical systems, based on measurements and on
the capacity of storing information. While both definitions are equivalent in
classical and quantum mechanics, they are in general different in generalized
probabilistic theories. We discuss in detail the case of a theory known as
'boxworld', and show that such a theory features systems with a dimension
mismatch. This dimension mismatch can be made arbitrarily large by using an
amplification procedure. Furthermore, we show that the dimension mismatch of
boxworld has strong consequences on its power for performing
information-theoretic tasks, leading to the collapse of communication
complexity and to the violation of information causality. Finally, we discuss
the consequences of a dimension mismatch from the perspective of
thermodynamics, and ask whether this effect could break Landauer's erasure
principle and thus the second law.


title: An Analysis of Random Projections in Cancelable Biometrics

abstract:
  With increasing concerns about security, the need for highly secure physical
biometrics-based authentication systems utilizing \emph{cancelable biometric}
technologies is on the rise. Because the problem of cancelable template
generation deals with the trade-off between template security and matching
performance, many state-of-the-art algorithms successful in generating high
quality cancelable biometrics all have random projection as one of their early
processing steps. This paper therefore presents a formal analysis of why random
projections is an essential step in cancelable biometrics. By formally defining
the notion of an \textit{Independent Subspace Structure} for datasets, it can
be shown that random projection preserves the subspace structure of data
vectors generated from a union of independent linear subspaces. The bound on
the minimum number of random vectors required for this to hold is also derived
and is shown to depend logarithmically on the number of data samples, not only
in independent subspaces but in disjoint subspace settings as well. The
theoretical analysis presented is supported in detail with empirical results on
real-world face recognition datasets.


title: Superconducting Nanowire Single Photon Detector on Diamond

abstract:
  Superconducting nanowire single photon detectors (SNSPDs) are fabricated
directly on diamond substrates and their optical and electrical properties are
characterized. Dark count performance and photon count rates are measured at
varying temperatures for 1310nm and 632nm photons. The procedure to prepare
diamond substrate surfaces suitable for the deposition and patterning of thin
film superconducting layers is reported. Using this approach, diamond
substrates with less than 300pm RMS surface roughness are obtained.


title: TeV-Scale strings

abstract:
  This article discusses the status of string physics where the string tension
is around the TeV scale. The article covers model building basics for
perturbative strings, based on D-brane configurations. The effective low energy
physics description of such string constructions is analyzed: how anomaly
cancellation is implemented, how fast proton decay is avoided and how D-brane
models lead to additional $Z'$ particles. This review also discusses direct
search bounds for strings at the TeV scale, as well as theoretical issues with
model building related to flavor physics and axions.


title: Temporal Logics for Hyperproperties

abstract:
  Two new logics for verification of hyperproperties are proposed.
Hyperproperties characterize security policies, such as noninterference, as a
property of sets of computation paths. Standard temporal logics such as LTL,
CTL, and CTL* can refer only to a single path at a time, hence cannot express
many hyperproperties of interest. The logics proposed here, HyperLTL and
HyperCTL*, add explicit and simultaneous quantification over multiple paths to
LTL and to CTL*. This kind of quantification enables expression of
hyperproperties. A model checking algorithm for the proposed logics is given.
For a fragment of HyperLTL, a prototype model checker has been implemented.


title:
Ignorance is bliss: General and robust cancellation of decoherence via
  no-knowledge quantum feedback

abstract:
  A "no-knowledge" measurement of an open quantum system yields no information
about any system observable; it only returns noise input from the environment.
Surprisingly, performing such a no-knowledge measurement can be advantageous.
We prove that a system undergoing no-knowledge monitoring has reversible noise,
which can be cancelled by directly feeding back the measurement signal. We show
how no-knowledge feedback control can be used to cancel decoherence in an
arbitrary quantum system coupled to a Markovian reservoir that is being
monitored. Since no-knowledge feedback does not depend on the system state or
Hamiltonian, such decoherence cancellation is guaranteed to be general, robust
and can operate in conjunction with any other quantum control protocol. As an
application, we show that no-knowledge feedback could be used to improve the
performance of dissipative quantum computers subjected to local loss.


title: Nonequilibrium Equalities in Absolutely Irreversible Processes

abstract:
  We generalize nonequilibrium integral equalities to situations involving
absolutely irreversible processes for which the forward-path probability
vanishes and the entropy production diverges, rendering conventional integral
fluctuation theorems inapplicable. We identify the mathematical origins of
absolute irreversibility as the singularity of probability measure. We
demonstrate the validity of the obtained equalities for several models.


title:
On the permutationally invariant part of a density matrix and
  nonseparability of N-qubit states

abstract:
  We consider the concept of "the permutationally invariant (PI) part of a
density matrix," which has proven very useful for both efficient quantum state
estimation and entanglement characterization of $N$-qubit systems. We show here
that the concept is, in fact, basis-dependent, but that this basis dependence
makes it an even more powerful concept than has been appreciated so far. By
considering the PI part $\rho^{{\rm PI}}$ of a general (mixed) $N$-qubit state
$\rho$, we obtain: (i) strong bounds on quantitative nonseparability measures,
(ii) a whole hierarchy of multi-partite separability criteria (one of which
entails a sufficient criterion for genuine $N$-partite entanglement) that can
be experimentally determined by just $2N+1$ measurement settings, (iii) a
definition of an efficiently measurable degree of separability, which can be
used for quantifying a novel aspect of decoherence of $N$ qubits, and (iv) an
explicit example that shows there are, for increasing $N$, genuinely
$N$-partite entangled states lying closer and closer to the maximally mixed
state. Moreover, we show that if the PI part of a state is $k$-nonseparable,
then so is the actual state. We further argue to add as requirement on any
multi-partite entanglement measure $E$ that it satisfy $E(\rho)\geq
E(\rho^{{\rm PI}})$, even though the operation that maps
$\rho\rightarrow\rho^{{\rm PI}}$ is not local.


title: IceCube - status and recent results

abstract:
  In May 2011, the IceCube neutrino observatory with one cubic kilometer
instrumented volume started full operation with 5160 sensors on 86 strings and
324 sensors on 162 IceTop detectors. The fine-tuning of operation and
calibration of the detector is still in progress while a very high uptime of
well above $98\%$ is obtained. New analysis techniques rely on veto techniques
for enhanced rejection of atmospheric muon and neutrino backgrounds. We will
give an overview of recent results including the techniques of searching for
starting tracks and some comments on the reported evidence of astrophysical
neutrinos at energies above 30 TeV.


title:
Evidence of Elevated X-Ray Absorption Before and During Major Flare
  Ejections in GRS 1915+105

abstract:
  We present time resolved X-ray spectroscopy of the microquasar GRS1915+105
with the MAXI observatory in order to study the accretion state just before and
during the ejections associated with its major flares. Radio monitoring with
the RATAN-600 radio telescope from 4.8 - 11.2 GHz has revealed two large steep
spectrum major flares in the first eight months of 2013. Since, the RATAN
receives one measurement per day, we cannot determine the jet forming time
without more information. Fortunately, this is possible since a distinct X-ray
light curve signature that occurs preceding and during major ejections has been
determined in an earlier study. The X-ray luminosity spikes to very high levels
in the hours before ejection then becomes variable (with a nearly equal X-ray
luminosity when averaged over the duration of the ejection) during a brief 3 to
8 hour ejection process. By comparing this X-ray behavior to MAXI light curves,
we can estimate the beginning and end of the ejection episode of the strong
2013 flares to within $\sim$3 hours. Using this estimate in conjunction with
time resolved spectroscopy from the data in the MAXI archives allows us to
deduce that the X-ray absorbing hydrogen column density increases significantly
in the hours preceding the ejections and remains elevated during the ejections
responsible for the major flares. This finding is consistent with an
out-flowing wind or enhanced accretion at high latitudes.


title: Random Walk on Random Walks

abstract:
  In this paper we study a random walk in a one-dimensional dynamic random
environment consisting of a collection of independent particles performing
simple symmetric random walks in a Poisson equilibrium with density $\rho \in
(0,\infty)$. At each step the random walk performs a nearest-neighbour jump,
moving to the right with probability $p_{\circ}$ when it is on a vacant site
and probability $p_{\bullet}$ when it is on an occupied site. Assuming that
$p_\circ \in (0,1)$ and $p_\bullet \neq \tfrac12$, we show that the position of
the random walk satisfies a strong law of large numbers, a functional central
limit theorem and a large deviation bound, provided $\rho$ is large enough. The
proof is based on the construction of a renewal structure together with a
multiscale renormalisation argument.


title: Testing for separability is hard

abstract:
  This paper shows that it is computationally hard to decide (or test) if a
consumption data set is consistent with separable preferences.


title:
The parallel replica method for simulating long trajectories of Markov
  chains

abstract:
  The parallel replica dynamics, originally developed by A.F. Voter,
efficiently simulates very long trajectories of metastable Langevin dynamics.
We present an analogous algorithm for discrete time Markov processes. Such
Markov processes naturally arise, for example, from the time discretization of
a continuous time stochastic dynamics. Appealing to properties of
quasistationary distributions, we show that our algorithm reproduces exactly
(in some limiting regime) the law of the original trajectory, coarsened over
the metastable states.


title:
Reconstructing Past Solar Activity using Meridian Solar Observations:
  the Case of the Royal Observatory of the Spanish Navy (1833-1840)

abstract:
  Solar meridian observations have been used to evaluate the solar activity of
the past. Some important examples are the solar meridian observations made at
the Basilica of San Petronio in Bologna by several astronomers and the
observations made by Hevelius published in his book Machina Coelestis. However,
we do not know whether these observations, which were not aimed to estimate the
solar activity, are reliable for evaluating solar activity. In this paper, we
present the marginal notes about sunspots that are included in the manuscripts
of the meridian solar observations made at the Royal Observatory of the Spanish
Navy during the period 1833-1840. We compare these observations with other
solar activity indices such as sunspot area and number. Our conclusion is that
solar meridian observations should be used with extreme caution to evaluate
past solar activity.


title: Infinite graphs that do not contain cycles of length four

abstract:
  We construct a countable infinite graph G that does not contain cycles of
length four having the property that the sequence of graphs $G_n$ induced by
the first $n$ vertices has minimum degree $\delta(G_n)> n^{\sqrt{2}-1+o(1)}$.


title:
Tracing the cosmic growth of super massive black holes to z ~ 3 with
  Herschel

abstract:
  We study a sample of Herschel-PACS selected galaxies within the GOODS-South
and the COSMOS fields in the framework of the PACS Evolutionary Probe (PEP)
project. Starting from the rich multi-wavelength photometric data-sets
available in both fields, we perform a broad-band Spectral Energy Distribution
(SED) decomposition to disentangle the possible active galactic nucleus (AGN)
contribution from that related to the host galaxy. We find that 37 per cent of
the Herschel-selected sample shows signatures of nuclear activity at the 99 per
cent confidence level. The probability to reveal AGN activity increases for
bright ($L_{\rm 1-1000} > 10^{11} \rm L_{\odot}$) star-forming galaxies at
$z>0.3$, becoming about 80 per cent for the brightest ($L_{\rm 1-1000} >
10^{12} \rm L_{\odot}$) infrared (IR) galaxies at $z \geq 1$. Finally, we
reconstruct the AGN bolometric luminosity function and the super-massive black
hole growth rate across cosmic time up to $z \sim 3$ from a Far-Infrared (FIR)
perspective. This work shows general agreement with most of the panchromatic
estimates from the literature, with the global black hole growth peaking at $z
\sim 2$ and reproducing the observed local black hole mass density with
consistent values of the radiative efficiency $\epsilon_{\rm rad}$
($\sim$0.07).


title:
Magnetic Moment and Band Structure Analysis of Fe, Co, Ni-modified
  Graphene-nano- ribbon

abstract:
  Magnetic properties and band characteristics of graphene-nano-ribbon (GNR)
modified by Fe, Co, and Ni were analyzed by the first principles DFT
calculation. Typical unit cell is [C32H2Fe1], [C32H2Co1] and [C32H2Ni1]
respectively. The most stable spin state was Sz=4/2 for Fe-modified GNR,
whereas Sz=3/2 for Co-case and Sz=2/2 for Ni-case. Atomic magnetic moment of
Fe, Co and Ni were 3.63, 2.49 and 1.26 {\mu}B, which were reduced values than
that of atomic Hund-rule due to magnetic coupling with graphene network. There
is a possibility for a ferromagnetic Fe, Co and Ni spin array through an
interaction with carbon pi-conjugated spin system. By expanding a unit cell of
Co-modified case as [C96H6Co3], ferromagnetic like spin state and ferrimagnetic
like one were compared. It was concluded that ferromagnetic state was more
stable magnetic state. Band calculations of Co-modified case show half-metal
like structure with relatively large band gap (0.55eV) for up-spin, whereas
small gap (0.05eV) for down-spin. This suggested a capability of spintronics
application like a spin fiter.


title:
Self-organized Voids Revisited: Experimental Verification of the
  Formation Mechanism*

abstract:
  In this paper, several experiments were conducted to further clarify the
formation mechanism of self organized void array induced by a single laser
beam, including energy-related experiments, refractive-index-contrast-related
experiments, depth-related experiments and effective-numerical-aperture
experiment. These experiments indicate that the interface spherical aberration
is indeed responsible for the formation of void arrays.


title:
Detection and Decoding for 2D Magnetic Recording Channels with 2D
  Intersymbol Interference

abstract:
  This paper considers iterative detection and decoding on the concatenated
communication channel consisting of a two-dimensional magnetic recording (TDMR)
channel modeled by the four-grain rectangular discrete grain model (DGM)
proposed by Kavcic et. al., followed by a two-dimensional intersymbol
interference (2D-ISI) channel modeled by linear convolution of the DGM model's
output with a finite-extent 2D blurring mask followed by addition of white
Gaussian noise. An iterative detection and decoding scheme combines TDMR
detection, 2D-ISI detection, and soft-in/soft-out (SISO) channel decoding in a
structure with two iteration loops. In the first loop, the 2D-ISI channel
detector exchanges log-likelihood ratios (LLRs) with the TDMR detector. In the
second loop, the TDMR detector exchanges LLRs with a serially concatenated
convolutional code (SCCC) decoder. Simulation results for the concatenated TDMR
and 2 x 2 averaging mask ISI channel with 10 dB SNR show that densities of 0.48
user bits per grain and above can be achieved, corresponding to an areal
density of about 9.6 Terabits per square inch, over the entire range of grain
probabilities in the TDMR model.


title: Using Quantum Computers to Learn Physics

abstract:
  Since its inception at the beginning of the twentieth century, quantum
mechanics has challenged our conceptions of how the universe ought to work;
however, the equations of quantum mechanics can be too computationally
difficult to solve using existing computers for even modestly large systems.
Here I will show that quantum computers can sometimes be used to address such
problems and that quantum computer science can assign formal complexities to
learning facts about nature. Hence, computer science should not only be
regarded as an applied science; it is also of central importance to the
foundations of science.


title: Direct detection of Light Anapole and Magnetic Dipole DM

abstract:
  We present comparisons of direct detection data for "light WIMPs" with an
anapole moment interaction (ADM) and a magnetic dipole moment interaction
(MDM), both assuming the Standard Halo Model (SHM) for the dark halo of our
galaxy and in a halo-independent manner. In the SHM analysis we find that a
combination of the 90% CL LUX and CDMSlite limits or the new 90% CL SuperCDMS
limit by itself exclude the parameter space regions allowed by DAMA, CoGeNT and
CDMS-II-Si data for both ADM and MDM. In our halo-independent analysis the new
LUX bound excludes the same potential signal regions as the previous XENON100
bound. Much of the remaining signal regions is now excluded by SuperCDMS, while
the CDMSlite limit is much above them. The situation is of strong tension
between the positive and negative search results both for ADM and MDM. We also
clarify the confusion in the literature about the ADM scattering cross section.


title:
When and By How Much Can Helper Node Selection Improve Regenerating
  Codes?

abstract:
  Regenerating codes (RCs) can significantly reduce the repair-bandwidth of
distributed storage networks. Initially, the analysis of RCs was based on the
assumption that during the repair process, the newcomer does not distinguish
(among all surviving nodes) which nodes to access, i.e., the newcomer is
oblivious to the set of helpers being used. Such a scheme is termed the blind
repair (BR) scheme. Nonetheless, it is intuitive in practice that the newcomer
should choose to access only those "good" helpers. In this paper, a new
characterization of the effect of choosing the helper nodes in terms of the
storage-bandwidth tradeoff is given. Specifically, answers to the following
fundamental questions are given: Under what conditions does proactively
choosing the helper nodes improve the storage-bandwidth tradeoff? Can this
improvement be analytically quantified?
  This paper answers the former question by providing a necessary and
sufficient condition under which optimally choosing good helpers strictly
improves the storage-bandwidth tradeoff. To answer the latter question, a
low-complexity helper selection solution, termed the family repair (FR) scheme,
is proposed and the corresponding storage/repair-bandwidth curve is
characterized. For example, consider a distributed storage network with 60
total number of nodes and the network is resilient against 50 node failures. If
the number of helper nodes is 10, then the FR scheme and its variant
demonstrate 27% reduction in the repair-bandwidth when compared to the BR
solution. This paper also proves that under some design parameters, the FR
scheme is indeed optimal among all helper selection schemes. An explicit
construction of an exact-repair code is also proposed that can achieve the
minimum-bandwidth-regenerating point of the FR scheme. The new exact-repair
code can be viewed as a generalization of the existing fractional repetition
code.


title: The Formation and Evolution of Small Star Clusters

abstract:
  Recent observations show that small, young, stellar groupings of ~10 to 40
members tend of have a centrally-located most massive member, reminiscent of
mass segregation seen in large clustered systems. Here, we analyze hydrodynamic
simulations which form small clusters and analyze their properties in a manner
identical to the observations. We find that the simulated clusters possess
similar properties to the observed clusters, including a tendency to exhibit
mass segregation. In the simulations, the central location of the most massive
member is not due to dynamical evolution, since there is little interaction
between the cluster members. Instead, the most massive cluster member appears
to form at the center. We also find that the more massive stars in the cluster
form at slightly earlier times.


title:
Fermi LAT detection of two high Galactic latitude gamma-ray sources,
  Fermi J1049.7+0435 and J1103.2+1145

abstract:
  The Second Fermi LAT source catalog (Nolan et al. 2012) includes as many as
1,873 sources, but initial attempts to identify counterparts at other
wavelengths resulted in 575 sources remaining unidentified. The 2FGL catalog is
based on the first 24 months of LAT observation since its launch in 2008, but
the LAT has now accumulated more than 5 years of high-energy gamma-ray data
almost flawlessly, presenting the possibility of finding new sources which were
too faint to be detected in the first two years of data or showed flaring
activity after the catalog was created. In this paper we report on two new
gamma-ray sources serendipitously discovered in the constellation Leo and
discuss possible counterparts based on radio observations.


title:
A quadratically tight partition bound for classical communication
  complexity and query complexity

abstract:
  In this work we introduce, both for classical communication complexity and
query complexity, a modification of the 'partition bound' introduced by Jain
and Klauck [2010]. We call it the 'public-coin partition bound'. We show that
(the logarithm to the base two of) its communication complexity and query
complexity versions form, for all relations, a quadratically tight lower bound
on the public-coin randomized communication complexity and randomized query
complexity respectively.


title: The Local Spin Structure of Large Spin Fermions

abstract:
  We show that large spin fermions have very rich spin structures. The local
spin order of a spin-$f$ Fermi gas is a linear combination of $2f$
(particle-hole) angular momentum states, $L=1,..,2f$. $L=1, 2$ represent
ferromagnetic and nematic spin order, while $L\geq 3$ are higher spin orders
that has no analog in spin-1/2 systems. Each $L$ spin sector is characterized
as $L$ pairs of antipodal points on a sphere. Model calculations show that some
of these spin-orders have the symmetry of Platonic solid, and many of them have
non-abelian line defects.


title:
Imaging and Spectroscopic Observations of a Filament Channel and the
  Implications for the Nature of Counter-streamings

abstract:
  The dynamics of a filament channel are observed with imaging and
spectroscopic telescopes before and during the filament eruption on 2011
January 29. The extreme ultraviolet (EUV) spectral observations reveal that
there is no EUV counterparts of the H$\alpha$ counter-streamings in the
filament channel, implying that the ubiquitous H$\alpha$ counter-streamings
found by previous research are mainly due to longitudinal oscillations of
filament threads, which are not in phase between each other. However, there
exist larger-scale patchy counter-streamings in EUV along the filament channel
from one polarity to the other, implying that there is another component of
uni-directional flow (in the range of $\pm$10 km s$^{-1}$) inside each filament
thread in addition to the implied longitudinal oscillation. Our results suggest
that the flow direction of the larger-scale patchy counter-streaming plasma in
the EUV is related to the intensity of the plage or active network, with the
upflows being located at brighter areas of the plage and downflows at the
weaker areas. Besides, we propose a new method to determine the chirality of an
erupting filament based on the skewness of the conjugate filament drainage
sites. It suggests that the right-skewed drainage corresponds to sinistral
chirality, whereas the left-skewed drainage corresponds to dextral chirality.


title: Explicit versus Spontaneous Diffeomorphism Breaking in Gravity

abstract:
  Gravitational theories with fixed background fields break local Lorentz and
diffeomorphism invariance either explicitly or spontaneously. In the case of
explicit breaking it is known that conflicts can arise between the dynamics and
geometrical constraints, while spontaneous breaking evades this problem. It is
for this reason that in the gravity sector of the Standard-Model Extension
(SME) it is assumed that the background fields (SME coefficients) originate
from spontaneous symmetry breaking. However, in other examples, such as
Chern-Simons gravity and massive gravity, diffeomorphism invariance is
explicitly broken by the background fields, and the potential conflicts between
the dynamics and geometry can be avoided in most cases. An analysis of how this
occurs is given, and the conditions that are placed on the metric tensor and
gravitational structure as a result of the presence of an explicit-breaking
background are described. The gravity sector of the SME is then considered for
the case of explicit breaking. However, it is found that a useful
post-Newtonian limit is only obtained when the symmetry breaking is
spontaneous.


title:
Solving reviewer assignment problem in software peer review: An approach
  based on preference matrix and asymmetric TSP model

abstract:
  Optimized reviewer assignment can effectively utilize limited intellectual
resources and significantly assure review quality in various scenarios such as
paper selection in conference or journal, proposal selection in funding
agencies and so on. However, little research on reviewer assignment of software
peer review has been found. In this study, an optimization approach is proposed
based on students' preference matrix and the model of asymmetric traveling
salesman problem (ATSP). Due to the most critical role of rule matrix in this
approach, we conduct a questionnaire to obtain students' preference matrices
and convert them to rule matrices. With the help of software ILOG CPLEX, the
approach is accomplished by controlling the exit criterion of ATSP model. The
comparative study shows that the assignment strategies with both reviewers'
preference matrix and authors' preference matrix get better performance than
the random assignment. Especially, it is found that the performance is just a
little better than that of random assignment when the reviewers' and authors'
preference matrices are merged. In other words, the majority of students have a
strong wish of harmonious development even though high-level students are not
willing to do that.


title:
Evolution of the 2D antiferromagnetism with temperature and magnetic
  field in multiferroic Ba$_2$CoGe$_2$O$_7$

abstract:
  We report on spherical neutron polarimetry and unpolarized neutron
diffraction in zero magnetic field as well as flipping ratio and static
magnetization measurements in high magnetic fields on the multiferroic square
lattice antiferromagnet Ba$_2$CoGe$_2$O$_7$. We found that in zero magnetic
field the magnetic space group is $Cm'm2'$ with sublattice magnetization
parallel to the [100] axis of this orthorhombic setting. The spin canting has
been found to be smaller than $0.2^\circ$ in the ground state. This assignment
is in agreement with the field-induced changes of the magnetic domain structure
below 40 mT as resolved by spherical neutron polarimetry. The magnitude of the
ordered moment has been precisely determined. Above the magnetic ordering
temperature short-range magnetic fluctuations are observed. Based on the
high-field magnetization data, we refined the parameters of the recently
proposed microscopic spin model describing the multiferroic phase of
Ba$_2$CoGe$_2$O$_7$.


title: Acceleration of magnetic dipoles by the sequence of current turns

abstract:
  Acceleration of magnetic dipoles is carried out by the running gradient of
the magnetic field formed while sequent switching on the current turns.
Magnetic dipoles, with a diameter of sixty millimeters and full length one
meter, are pre-accelerated by using the gas-dynamic method to speed one
kilometer per second, corresponding to the injection rate into the main
accelerator. To prevent the turning of the dipoles by one hundred eighty
degrees in the field of the accelerating pulse and focus them, the magnetic
dipoles are accelerated inside the titanium tube. The magnetic dipoles have
mass two kilograms and acquire the finite speed five kilometers per second on
the acceleration length three hundreds meters.


title:
Minor ion heating in spectra of linearly and circularly polarized
  Alfv\'{e}n waves: Thermal and non-thermal motions associated with
  perpendicular heating

abstract:
  Minor ion (such as $He^{2+}$) heating via nonresonant interaction with
spectra of linearly and circularly polarized Alfv\'{e}n waves (LPAWs and CPAWs
hereafter) is studied. The obtained analytic solutions are in good agreement
with the simulation results, indicating that newborn ions are heated by
low-frequency Alfv\'{e}n waves with finite amplitude in low-beta plasmas such
as the solar corona. The analytic solutions also reproduce the preferential
heating of heavy ions in the solar wind. In the presence of parallel
propagating Alfv\'{e}n waves, turbulence-induced particle motion is clearly
observed in the wave (magnetic field) polarized directions. After the waves
diminish, the newborn ions are heated, which is caused by the phase difference
(randomization) between ions due to their different parallel thermal motions.
The heating is dominant in the direction perpendicular to the ambient magnetic
field. The perpendicular heating,
$\eta=(T_{i\perp}^R-T_{i0\perp}^R)/T_{i0\perp}^R$ (where $T_{i0\perp}^R$ and
$T_{i\perp}^R$ are the perpendicular temperature of species $i$ before and
after genuine heating, respectively), in the spectrum of CPAWs is a factor of
two stronger than that of LPAWs. Moreover, we also study the effect of
field-aligned differential flow speed of species $i$ relative to $H^+$, $\delta
v_{ip} = (\mathbf{v_i}-\mathbf{v_p}) \cdot \mathbf{B} / |\mathbf{B}|$ (where
$\mathbf{v_i}$ and $\mathbf{v_p}$ denote vector velocities of the $H^+$ and
species $i$, respectively), on the perpendicular heating. It reveals that large
drift speed, $v_d=\delta v_{ip}$, has an effect on reducing the efficiency of
perpendicular heating, which is consistent with observations.


title:
Number of nodal domains of eigenfunctions on non-positively curved
  surfaces with concave boundary

abstract:
  It is an open problem in general to prove that there exists a sequence of
$\Delta_g$-eigenfunctions $\phi_{j_k}$ on a Riemannian manifold $(M, g)$ for
which the number $N(\phi_{j_k}) $ of nodal domains tends to infinity with the
eigenvalue. Our main result is that $N(\phi_{j_k}) \to \infty$ along a
subsequence of eigenvalues of density $1$ if the $(M, g)$ is a non-positively
curved surface with concave boundary, i.e. a generalized Sinai or Lorentz
billiard. Unlike the recent closely related work of Ghosh-Reznikov-Sarnak and
of the authors on the nodal domain counting problem, the surfaces need not have
any symmetries.


title:
Regularity for fully nonlinear nonlocal parabolic equations with rough
  kernels

abstract:
  We prove space and time regularity for solutions of fully nonlinear parabolic
integro-differential equations with rough kernels. We consider parabolic
equations $u_t = \I u$, where $\I$ is translation invariant and elliptic with
respect to the class $\mathcal L_0(\sigma)$ of Caffarelli and Silvestre,
$\sigma\in(0,2)$ being the order of $\I$. We prove that if $u$ is a viscosity
solution in $B_1 \times (-1,0]$ which is merely bounded in $\R^n \times
(-1,0]$, then $u$ is $C^\beta$ in space and $C^{\beta/\sigma}$ in time in
$\overline{B_{1/2}} \times [-1/2,0]$, for all $\beta< \min\{\sigma,
1+\alpha\}$, where $\alpha>0$. Our proof combines a Liouville type theorem
---relaying on the nonlocal parabolic $C^\alpha$ estimate of Chang and
D\'avila--- and a blow up and compactness argument.


title: Super edge-magic deficiency of join-product graphs

abstract:
  A graph $G$ is called \textit{super edge-magic} if there exists a bijective
function $f$ from $V(G) \cup E(G)$ to $\{1, 2, \ldots, |V(G) \cup E(G)|\}$ such
that $f(V(G)) = \{1, 2, \ldots, |V(G)|\}$ and $f(x) + f(xy) + f(y)$ is a
constant $k$ for every edge $xy$ of $G$. Furthermore, the \textit{super
edge-magic deficiency} of a graph $G$ is either the minimum nonnegative integer
$n$ such that $G \cup nK_1$ is super edge-magic or $+\infty$ if there exists no
such integer.
  \emph{Join product} of two graphs is their graph union with additional edges
that connect all vertices of the first graph to each vertex of the second
graph. In this paper, we study the super edge-magic deficiencies of a wheel
minus an edge and join products of a path, a star, and a cycle, respectively,
with isolated vertices.


title:
Axionic Antiferromagnetic Insulator Phase in a Correlated and Spin-Orbit
  Coupled System

abstract:
  We study theoretically a three-dimensional correlated and spin-orbit coupled
system, the half-filled extended Fu-Kane-Mele-Hubbard model on a diamond
lattice, focusing on the topological magnetoelectric response of the
antiferromagnetic insulator phase. In the antiferromagnetic insulator phase,
the Dirac-like low-energy effective Hamiltonian is obtained. Then the theta
term, which results in the magnetoelectric response, is derived as a
consequence of the chiral anomaly. The realization of the dynamical axion field
in our model is discussed. The relation with a symmetry broken phase induced by
interactions in lattice quantum chromodynamics is also discussed.

categories: cond-mat.str-el cond-mat.mes-hall cond-mat.mtrl-sci hep-ph


title: Electron-Phonon Superconductivity in LaO$_{0.5}$F$_{0.5}$BiSe$_{2}$

abstract:
  We report density functional calculations of the electronic structure, Fermi
surface, phonon spectrum and electron--phonon coupling for newly discovered
superconductor LaO$_{0.5}$F$_{0.5}$BiSe$_{2}$. Significant similarity between
LaO$_{0.5}$F$_{0.5}$BiS$_{2}$ and LaO$_{0.5}$F$_{0.5}$BiSe$_{2}$ is found, i.e.
there is a strong Fermi surface nesting at ($\pi $,$\pi $,0), which results in
unstable phonon branches. Combining the frozen phonon total energy calculations
and an anharmonic oscillator model, we find that the quantum fluctuation
prevents the appearance of static long--range order. The calculation shows that
LaO$_{0.5}$F$_{0.5}$BiSe$_{2}$ is highly anisotropic, and same as
LaO$_{0.5}$F$_{0.5}$BiS$_{2}$, this compound is also a conventional
electron-phonon coupling induced superconductor.


title: The boundary of the moduli space of stable cubic fivefolds

abstract:
  By GIT theory due to Mumford, the moduli space of stable cubic fivefolds is
compactified by adding non stable semi-stable (i.e. strictly semi-stable)
locus. In this paper, we prove that this locus consists of 19 components.
Moreover, we give a description of equation and singularity of cubic fivefold
corresponding to the generic point in each component.


title: Spin injection via (110)-grown semiconductor barriers

abstract:
  We study the tunneling of conduction electrons through a (110)-oriented
single-barrier heterostructure grown from III-V semiconductor compounds. It is
shown that, due to low spatial symmetry of such a barrier, the tunneling
current through the barrier leads to an electron spin polarization. The inverse
effect, generation of a direct tunneling current by spin polarized electrons,
is also predicted. We develop the microscopic theory of the effects and show
that the spin polarization emerges due to the combined action of the
Dresselhaus spin-orbit coupling within the barrier and the Rashba spin-orbit
coupling at the barrier interfaces.


title: High-z Supernova Type Ia Data: non-Gaussianity and Direction Dependence

abstract:
  We use the $\Delta_{\chi^2}$ statistic introduced in \cite{gup08,gup10} to
study directional dependence, in the high-z supernovae data. This dependence
could arise due to departures from the cosmological principle or from direction
dependent statistical systematics in the data. We apply our statistic to the
gold data set from \cite{rie04} and \cite{rie07}, and Union2 catalogue from
\cite{aman10}. Our results show that all the three data sets show a weak but
consistent direction dependence. In 2007 data errors are Gaussian, however
other two data sets show non-Gaussian features.


title: Mobile Adhoc Offloading

abstract:
  This problem is a series of biddings and auctions. Each round of bidding and
auction are different from previous ones because of the change of network
topology, variance of budget set by the sender, and possible evolution of
strategies of other nodes. The huge strategy space of relay nodes makes the
formulation to a game very difficult. We present a brief qualitative analysis
in this paper, and propose a bidding strategy based on learning algorithms.


title: General factorization framework for context-aware recommendations

abstract:
  Context-aware recommendation algorithms focus on refining recommendations by
considering additional information, available to the system. This topic has
gained a lot of attention recently. Among others, several factorization methods
were proposed to solve the problem, although most of them assume explicit
feedback which strongly limits their real-world applicability. While these
algorithms apply various loss functions and optimization strategies, the
preference modeling under context is less explored due to the lack of tools
allowing for easy experimentation with various models. As context dimensions
are introduced beyond users and items, the space of possible preference models
and the importance of proper modeling largely increases.
  In this paper we propose a General Factorization Framework (GFF), a single
flexible algorithm that takes the preference model as an input and computes
latent feature matrices for the input dimensions. GFF allows us to easily
experiment with various linear models on any context-aware recommendation task,
be it explicit or implicit feedback based. The scaling properties makes it
usable under real life circumstances as well.
  We demonstrate the framework's potential by exploring various preference
models on a 4-dimensional context-aware problem with contexts that are
available for almost any real life datasets. We show in our experiments --
performed on five real life, implicit feedback datasets -- that proper
preference modelling significantly increases recommendation accuracy, and
previously unused models outperform the traditional ones. Novel models in GFF
also outperform state-of-the-art factorization algorithms.
  We also extend the method to be fully compliant to the Multidimensional
Dataspace Model, one of the most extensive data models of context-enriched
data. Extended GFF allows the seamless incorporation of information into the
fac[truncated]


title:
Quantum rate theory of the trapping of hydrogen and deuterium by a
  vacancy in iron

abstract:
  We apply quantum rate theory to calculate the transition rates as hydrogen or
deuterium atoms escape from a vacancy trap in iron into a neighbouring
metastable site. We determine transition rates and corresponding activation
energies over a wide range of temperatures covering both the quantum and
classically dominated regimes. We find that quantum effects lead to an increase
of the transition rate activation energy and to very significant recrossing of
the transition state dividing surface. As a result of recrossing quantum
transition state theory overestimates the rate of proton transfer by more than
an order of magnitude and the rate of deuteron transfer by a factor of two.


title: Rellich Type Theorems for Unbounded Domains

abstract:
  We give several generalizations of Rellich's classical uniqueness theorem to
unbounded domains. We give a natural half-space generalization for
super-exponentially decaying inhomogeneities using real variable techniques. We
also prove under super-exponential decay a discrete generalization where the
inhomogeneity only needs to vanish in a suitable cone.
  The more traditional complex variable techniques are used to prove the
half-space result again, but with less exponential decay, and a variant with
polynomial decay, but with supports exponentially thin at infinity. As an
application, we prove the discreteness of non-scattering energies for
non-compactly supported potentials with suitable asymptotic behaviours and
supports.


title:
Polar Lattices for Strong Secrecy Over the Mod-$\Lambda$ Gaussian
  Wiretap Channel

abstract:
  Polar lattices, which are constructed from polar codes, are provably good for
the additive white Gaussian noise (AWGN) channel. In this work, we propose a
new polar lattice construction that achieves the secrecy capacity under the
strong secrecy criterion over the mod-$\Lambda$ Gaussian wiretap channel. This
construction leads to an AWGN-good lattice and a secrecy-good lattice
simultaneously. The design methodology is mainly based on the equivalence in
terms of polarization between the $\Lambda/\Lambda'$ channel in lattice coding
and the equivalent channel derived from the chain rule of mutual information in
multilevel coding.


title:
Government and Social Media: A Case Study of 31 Informational World
  Cities

abstract:
  Social media platforms are increasingly being used by governments to foster
user interaction. Particularly in cities with enhanced ICT infrastructures
(i.e., Informational World Cities) and high internet penetration rates, social
media platforms are valuable tools for reaching high numbers of citizens. This
empirical investigation of 31 Informational World Cities will provide an
overview of social media services used for governmental purposes, of their
popularity among governments, and of their usage intensity in broadcasting
information online.


title: A Case for Lorentzian Relativity

abstract:
  The Lorentz transformation (LT) is explained by changes occurring in the wave
characteristics of matter as it changes inertial frame. This explanation is
akin to that favoured by Lorentz, but informed by later insights, due primarily
to de Broglie, regarding the underlying unity of matter and radiation. To show
the nature of these changes, a massive particle is modelled as a standing wave
in three dimensions. As the particle moves, the standing wave becomes a
travelling wave having two factors. One is a carrier wave displaying the
dilated frequency and contracted ellipsoidal form described by the LT, while
the other (identified as the de Broglie wave) is a modulation defining the
dephasing of the carrier wave (and thus the failure of simultaneity) in the
direction of travel. The superluminality of the de Broglie wave is thus
explained, as are several other mysterious features of the optical behaviour of
matter, including the physical meaning of the Schr\"odinger Eqn. and the
relevance to scattering processes of the de Broglie wave number. Consideration
is given to what this Lorentzian approach to relativity might mean for the
possible existence of a preferred frame and the origin of the observed
Minkowski metric.


title:
Firm Detection of a Cyclotron Resonance Feature with Suzaku in the X-ray
  Spectrum of GRO J1008-57 during a Giant Outburst in 2012

abstract:
  We report on the firm detection of a cyclotron resonance scattering feature
(CRSF) in the X-ray spectrum of the Be X-ray binary pulsar, GRO J1008-57,
achieved by the Suzaku Hard X-ray Detector during a giant outburst which was
detected by the MAXI Gas Slit Camera in 2012 November. The Suzaku observation
was carried out on 2012 November 20, outburst maximum when the X-ray flux
reached $\sim 0.45$ Crab in 4-10 keV, which corresponds to a luminosity of $1.1
\times 10^{38}$ erg s$^{-1}$ in 0.5--100 keV at 5.8 kpc. The obtained broadband
X-ray spectrum from 0.5 keV to 118 keV revealed a significant absorption
feature, considered as the fundamental CRSF, at $\sim 76$ keV. This
unambiguously reconfirm the previously suggested $\sim$ 80 keV spectral feature
in GRO J1008$-$57. The implied surface magnetic field, $6.6\times 10^{12}$ G,
is the highest among binary X-ray pulsars from which CRSFs have ever been
detected.


title: Quantum Rings in Magnetic Fields and Spin Current Generation

abstract:
  We propose three different mechanisms for pumping spin-polarized currents in
a ballistic circuit using a time-dependent magnetic field acting on an
asymmetrically connected quantum ring at half filling. The first mechanism
works thanks to a rotating magnetic field and produces an alternating current
with a partial spin polarization. The second mechanism works by rotating the
ring in a constant field; like the former case, it produces an alternating
charge current but the spin current is d.c.; both methods do not require a
spin-orbit interaction to achieve the polarized current, but the rotating ring
could be used to measure the spin-orbit interaction in the ring using
characteristic oscillations. On the other hand, the last mechanism that we
propose depends on the spin-orbit interaction in an essential way, and requires
a time-dependent magnetic field in the plane of the ring. This arrangement can
be designed to pump a purely spin current. The absence of a charge current is
demonstrated analytically. Moreover, a simple formula for the current is
derived and compared to the numerical results.


title:
The colored Kauffman skein relation and the head and tail of the colored
  Jones polynomial

abstract:
  Using the colored Kauffman skein relation, we study the highest and lowest
$4n$ coefficients of the $n^{th}$ unreduced colored Jones polynomial of
alternating links. This gives a natural extension of a result by Kauffman in
regard with the Jones polynomial of alternating links and its highest and
lowest coefficients. We also use our techniques to give a new and natural proof
for the existence of the tail of the colored Jones polynomial for alternating
links.


title: Dialectica models of additive-free linear logic

abstract:
  This paper presents a construction which transforms categorical models of
additive-free propositional linear logic, closely based on de Paiva's
dialectica categories and Oliva's functional interpretations of classical
linear logic. The construction is defined using dependent type theory, which
proves to be a useful tool for reasoning about dialectica categories.
Abstractly, we have a closure operator on the class of models: it preserves
soundness and completeness and has a monad-like structure. When applied to
categories of games we obtain `games with bidding', which are hybrids of
dialectica and game models, and we prove completeness theorems for two specific
such models.


title:
Solving the Minimum Common String Partition Problem with the Help of
  Ants

abstract:
  In this paper, we consider the problem of finding a minimum common partition
of two strings. The problem has its application in genome comparison. As it is
an NP-hard, discrete combinatorial optimization problem, we employ a
metaheuristic technique, namely, MAX-MIN ant system to solve this problem. To
achieve better efficiency we first map the problem instance into a special kind
of graph. Subsequently, we employ a MAX-MIN ant system to achieve high quality
solutions for the problem. Experimental results show the superiority of our
algorithm in comparison with the state of art algorithm in the literature. The
improvement achieved is also justified by standard statistical test.


title: From mobile phone data to the spatial structure of cities

abstract:
  Pervasive infrastructures, such as cell phone networks, enable to capture
large amounts of human behavioral data but also provide information about the
structure of cities and their dynamical properties. In this article, we focus
on these last aspects by studying phone data recorded during 55 days in 31
Spanish metropolitan areas. We first define an urban dilatation index which
measures how the average distance between individuals evolves during the day,
allowing us to highlight different types of city structure. We then focus on
hotspots, the most crowded places in the city. We propose a parameter free
method to detect them and to test the robustness of our results. The number of
these hotspots scales sublinearly with the population size, a result in
agreement with previous theoretical arguments and measures on employment
datasets. We study the lifetime of these hotspots and show in particular that
the hierarchy of permanent ones, which constitute the "heart" of the city, is
very stable whatever the size of the city. The spatial structure of these
hotspots is also of interest and allows us to distinguish different categories
of cities, from monocentric and "segregated" where the spatial distribution is
very dependent on land use, to polycentric where the spatial mixing between
land uses is much more important. These results point towards the possibility
of a new, quantitative classification of cities using high resolution
spatio-temporal data.


title:
Nonstationary iterated Tikhonov regularization in Banach spaces with
  uniformly convex penalty terms

abstract:
  We consider the nonstationary iterated Tikhonov regularization in Banach
spaces which defines the iterates via minimization problems with uniformly
convex penalty term. The penalty term is allowed to be non-smooth to include
$L^1$ and total variation (TV) like penalty functionals, which are significant
in reconstructing special features of solutions such as sparsity and
discontinuities in practical applications. We present the detailed convergence
analysis and obtain the regularization property when the method is terminated
by the discrepancy principle. In particular we establish the strong convergence
and the convergence in Bregman distance which sharply contrast with the known
results that only provide weak convergence for a subsequence of the iterative
solutions. Some numerical experiments on linear integral equations of first
kind and parameter identification in differential equations are reported.


title:
Convergence rate of stability problems of SDEs with (dis-)continuous
  coefficients

abstract:
  We consider the stability problems of one dimensional SDEs when the diffusion
coefficients satisfy the so called Nakao-Le Gall condition. The explicit rate
of convergence of the stability problems are given by the Yamada-Watanabe
method without the drifts. We also discuss the convergence rate for the SDEs
driven by the symmetric $\alpha$ stable process. These stability rate problems
are extended to the case where the drift coefficients are bounded and in $L^1$.
It is shown that the convergence rate is invariant under the removal of drift
method for the SDEs driven by the Wiener process.


title:
On the Potential of Twitter for Understanding the Tunisia of the
  Post-Arab Spring

abstract:
  Micro-blogging through Twitter has made information short and to the point,
and more importantly systematically searchable. This work is the first of a
series in which quotidian observations about Tunisia are obtained using the
micro-blogging site Twitter. Data was extracted using the open source Twitter
API v1.1. Specific tweets were obtained using functional search operators in
particular thematic hash tags, geo-location, date, time and language. The
presence of Tunisia in the international tweet stream, the language of
communication of Tunisian residents through Twitter as well as Twitter usage
across Tunisia are the center of attention of this article.


title:
Magnetically driven winds from differentially rotating neutron stars and
  X-ray afterglows of short gamma-ray bursts

abstract:
  Besides being among the most promising sources of gravitational waves,
merging neutron star binaries also represent a leading scenario to explain the
phenomenology of short gamma-ray bursts (SGRBs). Recent observations have
revealed a large subclass of SGRBs with roughly constant luminosity in their
X-ray afterglows, lasting $10\!-\!10^4$ s. These features are generally taken
as evidence of a long-lived central engine powered by the magnetic spin-down of
a uniformly rotating, magnetized object. We propose a different scenario in
which the central engine powering the X-ray emission is a differentially
rotating hypermassive neutron star (HMNS) that launches a quasi-isotropic and
baryon-loaded wind driven by the magnetic field, which is built-up through
differential rotation. Our model is supported by long-term, three-dimensional,
general-relativistic, and ideal magnetohydrodynamic simulations, showing that
this isotropic emission is a very robust feature. For a given HMNS, the
presence of a collimated component depends sensitively on the initial magnetic
field geometry, while the stationary electromagnetic luminosity depends only on
the magnetic energy initially stored in the system. We show that our model is
compatible with the observed timescales and luminosities and express the latter
in terms of a simple scaling relation.


title: Modelling the Hidden Magnetic Field of Low-Mass Stars

abstract:
  Zeeman-Doppler imaging is a spectropolarimetric technique that is used to map
the large-scale surface magnetic fields of stars. These maps in turn are used
to study the structure of the stars' coronae and winds. This method, however,
misses any small-scale magnetic flux whose polarisation signatures cancel out.
Measurements of Zeeman broadening show that a large percentage of the surface
magnetic flux may be neglected in this way. In this paper we assess the impact
of this 'missing flux' on the predicted coronal structure and the possible
rates of spin down due to the stellar wind. To do this we create a model for
the small-scale field and add this to the Zeeman-Doppler maps of the magnetic
fields of a sample of 12 M dwarfs. We extrapolate this combined field and
determine the structure of a hydrostatic, isothermal corona. The addition of
small-scale surface field produces a carpet of low-lying magnetic loops that
covers most of the surface, including the stellar equivalent of solar 'coronal
holes' where the large-scale field is opened up by the stellar wind and hence
would be X-ray dark. We show that the trend of the X-ray emission measure with
rotation rate (the so-called 'activity-rotation relation') is unaffected by the
addition of small-scale field, when scaled with respect to the large-scale
field of each star. The addition of small-scale field increases the surface
flux; however, the large-scale open flux that governs the loss of mass and
angular momentum in the wind remains unaffected. We conclude that spin-down
times and mass loss rates calculated from surface magnetograms are unlikely to
be significantly influenced by the neglect of small-scale field.


title:
Maximal neutron star mass and the resolution of hyperon puzzle in
  modified gravity

abstract:
  The so-called hyperon puzzle in the theory of neutron stars is considered in
the framework of modified $f(R)$ gravity. We show that for simple hyperon
equations of state, it is possible to obtain the maximal neutron star mass
which satisfies the recent observational data for PSR J1614-2230, in
higher-derivative models with power-law terms as $f(R) = R+\alpha R^2+ \beta
R^3$. The soft hyperon equation of state under consideration is usually treated
as non-realistic in the standard General Relativity. The numerical analysis of
Mass-Radius relation for massive neutron stars with hyperon equation of state
in modified gravity turns out to be consistent with observations. Thus, we show
that the same modified gravity can solve at once three problems: consistent
description of the maximal mass of neutron star, realistic Mass-Radius relation
and account for hyperons in equation of state.


title: Phenomenology of the $ppK^+K^-$ system near threshold

abstract:
  In this article studies of the near threshold $pp\to ppK^+K^-$ reaction
conducted with the COSY-11 and the ANKE detectors are reviewed. In particular
recent investigations on the $K^+K^-$ final state interaction are revisited
taking into account updated cross sections of the COSY-11 experiment. These
studies resulted in the new value of $K^+K^-$ effective range amounting to:
$\mathrm{Re}(b_{K^{+}K^{-}}) =
-0.2^{+0.8_{stat}~+0.4_{sys}}_{-0.6_{stat}~-0.4_{sys}}~\mathrm{fm}$ and
$\mathrm{Im}(b_{K^{+}K^{-}}) =
1.2^{~+0.5_{stat}~+0.3_{sys}}_{~-0.3_{stat}~-0.3_{sys}}~\mathrm{fm}$. The
determined real and imaginary parts of the $K^+K^-$ scattering length were
estimated to be: $\left|\mathrm{Re}(a_{K^{+}K^{-}})\right| =
10^{~+17_{stat}}_{~-10_{stat}}~\mathrm{fm}$ and $\mathrm{Im}(a_{K^{+}K^{-}}) =
0^{~+37_{stat}}_{~-10_{stat}}~\mathrm{fm}$.


title:
Nonlocal-in-time action for the fourth post-Newtonian conservative
  dynamics of two-body systems

abstract:
  We complete the analytical determination, at the 4th post-Newtonian (4PN)
approximation, of the conservative dynamics of gravitationally interacting
two-point-mass systems. This completion is obtained by resolving the infra-red
ambiguity which had blocked a previous 4PN calculation [P.Jaranowski and
G.Sch\"afer, Phys. Rev. D 87, 081503(R) (2013)] by taking into account the 4PN
breakdown of the usual near-zone expansion due to infinite-range
tail-transported temporal correlations found long ago [L.Blanchet and T.Damour,
Phys. Rev. D 37, 1410 (1988)]. This leads to a Poincar\'e-invariant
4PN-accurate effective action for two masses, which mixes instantaneous
interaction terms (described by a usual Hamiltonian) with a (time-symmetric)
nonlocal-in-time interaction.

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


title: Non-stability of Paneitz-Branson equations in arbitrary dimensions

abstract:
  Let $(M,g)$ be a compact riemannian manifold of dimension $n\geq 5$. We are
interested in the stability of a slighly subcritical Paneitz-Branson type
equation on $M$. Assuming that there exists a positive nondegenerate solution
of the critical equation and under suitable conditions, we prove that this
equation is not stable for all $n\geq 5$.


title: Wealth distribution and collective knowledge. A Boltzmann approach

abstract:
  We introduce and discuss a nonlinear kinetic equation of Boltzmann type which
describes the influence of knowledge in the evolution of wealth in a system of
agents which interact through the binary trades introduced in Cordier,
Pareschi, Toscani, J. Stat. Phys. 2005. The trades, which include both saving
propensity and the risks of the market, are here modified in the risk and
saving parameters, which now are assumed to depend on the personal degree of
knowledge. The numerical simulations show that the presence of knowledge has
the potential to produce a class of wealthy agents and to account for a larger
proportion of wealth inequality.


title: Von Neumann spin measurements with Rashba fields

abstract:
  We show that dynamics in spin-orbit coupling field simulates the von Neumann
measurement of a particle spin. We demonstrate how the measurement influences
the spin and coordinate evolution of a particle by comparing two examples of
such a procedure. First example is a simultaneous measurement of spin
components, $\sigma _{x}$ and $\sigma _{y}$, corresponding to non-commuting
operators, which cannot be accurately obtained together at a given time instant
due to the Heisenberg uncertainty ratio. By mapping spin dynamics onto a
spatial walk such a procedure determines measurement-time averages of $\sigma
_{x}$ and $\sigma _{y}$, which already can be precisely evaluated in a single
short-time measurement. The other, qualitatively different, example is the spin
of a one-dimensional particle in a magnetic field. Here the outcome depends on
the angle between the spin-orbit coupling and magnetic fields. These results
can be applied to studies of spin-orbit coupled cold atoms and electrons in
solids.


title: Formation of a Buffer Layer for Graphene on C-face SiC{0001}

abstract:
  Graphene films prepared by heating the SiC(000-1) surface (the C-face of the
{0001} surfaces) in a Si-rich environment are studied using low-energy electron
diffraction (LEED) and low-energy electron microscopy (LEEM). Upon
graphitization, an interface with rt(43) x rt(43)-R7.6 degree symmetry is
observed by in situ LEED. After oxidation, the interface displays rt(3) x
rt(3)-R30 degree symmetry. Electron reflectivity measurements indicate that
these interface structures arise from a graphene-like "buffer layer" that forms
between the graphene and the SiC, similar to that observed on Si-face SiC. From
a dynamical LEED structure calculation for the oxidized C-face surface, it is
found to consist of a graphene layer sitting on top of a silicate (Si2O3)
layer, with the silicate layer having the well-known structure as previously
studied on bare SiC(000-1) surfaces. Based on this result, the structure of the
interface prior to oxidation is discussed.


title:
Effect of line defects on the electrical transport properties of
  monolayer MoS$_{2}$ sheet

abstract:
  We present a computational study on the impact of line defects on the
electronic properties of monolayer MoS2. Four different kinds of line defects
with Mo and S as the bridging atoms, consistent with recent theoretical and
experimental observations are considered herein. We employ the density
functional tight-binding (DFTB) method with a Slater-Koster type DFTB-CP2K
basis set for evaluating the material properties of perfect and the various
defective MoS2 sheets. The transmission spectra is computed with a
DFTB-Non-Equilibrium Greens Function (NEGF) formalism. We also perform a
detailed analysis of the carrier transmission pathways under a small bias and
investigate the phase shifts in the transmission eigenstates of the defective
MoS2 sheets. Our simulations show a 2-4 folds decrease in carrier conductance
of MoS2 sheets in the presence of line defects as compared to that for the
perfect sheet.


title: Position and Spin Control by Dynamical Ultrastrong Spin-Orbit Coupling

abstract:
  Focusing on the efficient probe and manipulation of single-particle spin
states, we investigate the coupled spin and orbital dynamics of a spin 1/2
particle in a harmonic potential subject to ultrastrong spin-orbit interaction
and external magnetic field. The advantage of these systems is the clear
visualization of the strong spin-orbit coupling in the orbital dynamics. We
also investigate the effect of a time-dependent coupling: Its nonadiabatic
change causes an interesting interplay of spin and orbital motion which is
related to the direction and magnitude of the applied magnetic field. This
result suggests that orbital state manipulation can be realized through
ultrastrong spin-orbit interactions, becoming a useful tool for handling
entangled spin and orbital degrees of freedom to produce, for example, spin
desirable polarizations in time interesting for spintronics implementations.


title: Room temperature Bloch surface wave polaritons

abstract:
  Polaritons are hybrid light-matter quasi-particles that have gathered a
significant attention for their capability to show room temperature and
out-of-equilibrium Bose-Einstein condensation. More recently, a novel class of
ultrafast optical devices have been realized by using flows of polariton
fluids, such as switches, interferometers and logical gates. However, polariton
lifetimes and propagation distance are strongly limited by photon losses and
accessible in-plane momenta in usual microcavity samples. In this work, we show
experimental evidence of the formation of room temperature propagating
polariton states arising from the strong coupling between organic excitons and
a Bloch surface wave. This result, which was only recently predicted, paves the
way for the realization of polariton devices that could allow lossless
propagation up to macroscopic distances.


title: Kloosterman Sums with Multiplicative Coefficients

abstract:
  Let $f(n)$ be a multiplicative function satisfying $|f(n)|\leq 1$, $q$ $(\leq
N^2)$ be a positive integer and $a$ be an integer with $(a,\,q)=1$. In this
paper, we shall prove that $$\sum_{\substack{n\leq N\\
(n,\,q)=1}}f(n)e({a\bar{n}\over q})\ll\sqrt{\tau(q)\over
q}N\log\log(6N)+q^{{1\over 4}+{\epsilon\over 2}}N^{1\over 2}(\log(6N))^{1\over
2}+{N\over \sqrt{\log\log(6N)}},$$ where $\bar{n}$ is the multiplicative
inverse of $n$ such that $\bar{n}n\equiv 1\,({\rm mod}\,q),\,e(x)=\exp(2\pi
ix),\,\tau(q)$ is the divisor function.


title: The Green-function transform and wave propagation

abstract:
  Fourier methods well known in signal processing are applied to
three-dimensional wave propagation problems. The Fourier transform of the Green
function, when written explicitly in terms of a real-valued spatial frequency,
consists of homogeneous and inhomogeneous components. Both parts are necessary
to result in a pure out-going wave that satisfies causality. The homogeneous
component consists only of propagating waves, but the inhomogeneous component
contains both evanescent and propagating terms. Thus we make a distinction
between inhomogenous waves and evanescent waves. The evanescent component is
completely contained in the region of the inhomogeneous component outside the
k-space sphere. Further, propagating waves in the Weyl expansion contain both
homogeneous and inhomogeneous components. The connection between the Whittaker
and Weyl expansions is discussed. A list of relevant spherically symmetric
Fourier transforms is given.


title: Quantum Dynamics of the Driven and Dissipative Rabi Model

abstract:
  The Rabi model considers a two-level system (or spin-1/2) coupled to a
quantized harmonic oscillator and describes the simplest interaction between
matter and light. The recent experimental progress in solid-state circuit
quantum electrodynamics has engendered theoretical efforts to quantitatively
describe the mathematical and physical aspects of the light-matter interaction
beyond the rotating wave approximation. We develop a stochastic Schr\"{o}dinger
equation approach which enables us to access the strong-coupling limit of the
Rabi model and study the effects of dissipation, and AC drive in an exact
manner. We include the effect of ohmic noise on the non-Markovian spin dynamics
resulting in Kondo-type correlations, as well as cavity losses. We compute the
time evolution of spin variables in various conditions. As a consideration for
future work, we discuss the possibility to reach a steady state with one
polariton in realistic experimental conditions.


title: $\mu-\tau$ Symmetry, Nonzero $\theta_{13}$, and CP Violation

abstract:
  If we impose the $\mu-\tau$ symmetry, as a constraint into neutrino mass
matrix, one find that the Jarlskog rephasing invariant: $J_{\rm CP}=0$ which
implies that CP violation cannot be accommodated in the $\mu-\tau$ symmetry
scheme. By introducing a small parameter $x$ that perturb the neutrino mass
matrix with $\mu-\tau$ symmetry with trace of neutrino mass matrix remain
constant, we can obtain $J_{CP}\neq 0$ and consequently $\theta_{13}\neq 0$.


title: On a class of $q$-Bernoulli, $q$-Euler and $q$-Genocchi polynomials

abstract:
  The main purpose of this paper is to introduce and investigate a class of
$q$-Bernoulli, $q$-Euler and $q$-Genocchi polynomials. The $q$-analogues of
well-known formulas are derived. The $q$-analogue of the Srivastava--Pint\'er
addition theorem is obtained. Some new identities involving $q$-polynomials are
proved.


title:
Hyperbolic statistics and entropy loss in the description of gene
  distributions

abstract:
  Zipf's law implies the statistical distributions of hyperbolic type, which
can describe the properties of stability and entropy loss in linguistics. We
present the information theory from which follows that if the system is
described by distributions of hyperbolic type it leads to the possibility of
entropy loss. We present the number of repetitions of genes in tne genomes for
some bacteria, as Borelia burgdorferi and Escherichia coli.
  Distributions of repetitions of genes in genome appears to be represented by
distributions of hyperbolic type.


title:
Accelerating NLTE radiative transfer by means of the Forth-and-Back
  Implicit Lambda Iteration: A two-level atom line formation in 2D Cartesian
  coordinates

abstract:
  State-of-the-art methods in multidimensional NLTE radiative transfer are
based on the use of local approximate lambda operator within either Jacobi or
Gauss-Seidel iterative schemes. Here we propose another approach to the
solution of 2D NLTE RT problems, Forth-and-Back Implicit Lambda Iteration
(FBILI), developed earlier for 1D geometry. In order to present the method and
examine its convergence properties we use the well-known instance of the
two-level atom line formation with complete frequency redistribution. In the
formal solution of the RT equation we employ short characteristics with
two-point algorithm. Using an implicit representation of the source function in
the computation of specific intensities, we compute and store the coefficients
of the linear relations J = a + bS between the mean intensity J and the
corresponding source function S. The use of iteration factors in the 'local'
coefficients of these implicit relations in two 'inward' directions, along with
the update of the source function in other two, 'outward', directions leads to
four times faster solution than the Jacobi's one. Moreover, the update made in
all four consecutive sweeps of the grid leads to an acceleration by a factor of
6-7 compared to the Jacobi iterative scheme.


title:
$L^2$-Serre duality on singular complex spaces and rational
  singularities

abstract:
  In the present paper, we devise a version of topological $L^2$-Serre duality
for singular complex spaces with arbitrary singularities. This duality is used
to deduce various new $L^2$-vanishing theorems for the
$\bar{\partial}$-equation on singular spaces. It is shown that complex spaces
with rational singularities behave quite tame with respect to the
$\bar{\partial}$-equation in the $L^2$-sense. More precisely: a singular point
is rational if and only if the $L^2$-$\bar{\partial}$-complex is exact in this
point. So, we obtain an $L^2$-$\bar{\partial}$-resolution of the structure
sheaf in rational singular points.


title:
Building meromorphic solutions of $q$-difference equations using a
  Borel-Laplace summation

abstract:
  After introducing q-analogues of the Borel and Laplace transformations, we
prove that to every formal power series solution of a linear q-difference
equation with rational coefficients, we may apply several q-Borel and Laplace
transformations of convenient orders and convenient direction in order to
construct a solution of the same equation that is meromorphic on
$\mathbb{C}^{*}$. We use this theorem to construct explicitly an invertible
matrix solution of a linear q-difference system with rational coefficients, of
which entries are meromorphic on $\mathbb{C}^{*}$. Moreover, when the system is
put in the Birkhoff-Guenther normal form, we prove that the solutions we
compute are exactly the same as the one constructed by Ramis, Sauloy and Zhang.


title: Refined masses and distance of the young binary Haro 1-14 C

abstract:
  We aim to refine the dynamical masses of the individual component of the
low-mass pre-main sequence binary Haro 1-14 C. We combine the data of the
preliminary orbit presented previously with new interferometric observations
obtained with the four 8m telescopes of the Very Large Telescope
Interferometer. The derived masses are $M_a=0.905\pm0.043\,\Msun$ and
$M_b=0.308\pm0.011\,\Msun$ for the primary and secondary components,
respectively. This is about five times better than the uncertainties of the
preliminary orbit. Moreover, the possibility of larger masses is now securely
discarded. The new dynamical distance, $d=96\pm\,9\,$pc, is smaller than the
distance to the Ophiuchus core with a significance of $2.6\,\sigma$. Fitting
the spectral energy distribution yields apparent diameters of
$\phi_a=0.13\pm0.01\mas$ and $\phi_b=0.10\pm0.01\mas$ (corresponding to
$\Ra=1.50\,\Rsun$ and $\Rb=1.13\,\Rsun$) and a visual extinction of
$A_v\approx1.75$. Although the revised orbit has a nearly edge-on geometry, the
system is unlikely to be a long-period eclipsing binary. The secondary in
Haro~1-14C is one of the few low-mass, pre-main sequence stars with an
accurately determined dynamical mass and distance.


title: Excess Risk Bounds for Exponentially Concave Losses

abstract:
  The overarching goal of this paper is to derive excess risk bounds for
learning from exp-concave loss functions in passive and sequential learning
settings. Exp-concave loss functions encompass several fundamental problems in
machine learning such as squared loss in linear regression, logistic loss in
classification, and negative logarithm loss in portfolio management. In batch
setting, we obtain sharp bounds on the performance of empirical risk
minimization performed in a linear hypothesis space and with respect to the
exp-concave loss functions. We also extend the results to the online setting
where the learner receives the training examples in a sequential manner. We
propose an online learning algorithm that is a properly modified version of
online Newton method to obtain sharp risk bounds. Under an additional mild
assumption on the loss function, we show that in both settings we are able to
achieve an excess risk bound of $O(d\log n/n)$ that holds with a high
probability.


title: Essentially optimal interactive certificates in linear algebra

abstract:
  Certificates to a linear algebra computation are additional data structures
for each output, which can be used by a---possibly randomized---verification
algorithm that proves the correctness of each output. The certificates are
essentially optimal if the time (and space) complexity of verification is
essentially linear in the input size $N$, meaning $N$ times a factor
$N^{o(1)}$, i.e., a factor $N^{\eta(N)}$ with $\lim\_{N\to \infty} \eta(N)$ $=$
$0$. We give algorithms that compute essentially optimal certificates for the
positive semidefiniteness, Frobenius form, characteristic and minimal
polynomial of an $n\times n$ dense integer matrix $A$. Our certificates can be
verified in Monte-Carlo bit complexity $(n^2 \log\|A\|)^{1+o(1)}$, where
$\log\|A\|$ is the bit size of the integer entries, solving an open problem in
[Kaltofen, Nehring, Saunders, Proc.\ ISSAC 2011] subject to computational
hardness assumptions. Second, we give algorithms that compute certificates for
the rank of sparse or structured $n\times n$ matrices over an abstract field,
whose Monte Carlo verification complexity is $2$ matrix-times-vector products
$+$ $n^{1+o(1)}$ arithmetic operations in the field. For example, if the
$n\times n$ input matrix is sparse with $n^{1+o(1)}$ non-zero entries, our rank
certificate can be verified in $n^{1+o(1)}$ field operations. This extends also
to integer matrices with only an extra $\|A\|^{1+o(1)}$ factor. All our
certificates are based on interactive verification protocols with the
interaction removed by a Fiat-Shamir identification heuristic. The validity of
our verification procedure is subject to standard computational hardness
assumptions from cryptography.


title: Strong edge-colouring of sparse planar graphs

abstract:
  A strong edge-colouring of a graph is a proper edge-colouring where each
colour class induces a matching. It is known that every planar graph with
maximum degree $\Delta$ has a strong edge-colouring with at most $4\Delta+4$
colours. We show that $3\Delta+1$ colours suffice if the graph has girth 6, and
$4\Delta$ colours suffice if $\Delta\geq 7$ or the girth is at least 5. In the
last part of the paper, we raise some questions related to a long-standing
conjecture of Vizing on proper edge-colouring of planar graphs.


title:
Stabilisation de la formule des traces tordue I: endoscopie tordue sur
  un corps local

abstract:
  This is the first of a series of papers devoted to the stabilization of the
twisted trace formula. It is just an introduction. We present the local theory
of twisted endoscopy, following the fundamental works of Kottwitz-Shelstad,
Labesse and Shelstad. Our presentation is partly new because we try to give
canonical definitions of the basic objects, which are more usually defined
using auxiliary data. We prove also some results about the image of endoscopic
transfer and about the dual transfer of stable distributions whose support is a
finite set of stable conjugacy classes.


title:
Predicting the steady state thickness of passive films in order to
  prevent degradations of implant

abstract:
  Some implants have approximately a lifetime of 15 years. The femoral stem,
for example, should be made of 316L/316LN stainless steel. Fretting corrosion,
friction under small displacements, should occur during human gait, due to
repeated loadings and un-loadings, between stainless steel and bone for
instance. Some experimental investigations of fretting corrosion have been
practiced. As well known, metallic alloys and especially stainless steels are
covered with a passive film that prevents from the corrosion and degradation.
This passive layer of few nanometers, at ambient temperature, is the key of our
civilization according to some authors. This work is dedicated to predict the
passive layer thicknesses of stainless steel under fretting corrosion with a
specific emphasis on the role of proteins. The model is based on the Point
Defect Model (micro scale) and an update of the model on the friction process
(micro-macro scale). Genetic algorithm was used for finding solution of the
problem. The major results are, as expected from experimental results, albumin
prevents from degradation at the lowest concentration of chlorides; an
incubation time is necessary for degrading the passive film; under fretting
corrosion and high concentration of chlorides the passive behavior is
annihilated.


title:
Quantum discord and one-norm geometric quantum discord for XXX
  Heisenberg spin chain under noisy channels

abstract:
  Here, we compare the behavior of the quantum discord, 1-norm geometric
quantum discord and concurrence under the effect of decoherence for XXX
Heisenberg spin chain. Their dependencies on temperature and coupling constant
are presented in detail. By a comparison between them we can see that quantum
discord and 1-norm geometric quantum discord are more robust than the
concurrence against decoherence in the sense that quantum discord and 1-norm
geometric quantum discord takes a nonzero value and decrease asymptotically,
while the concurrence is zero in a large range of parameters including
temperature and coupling constant. Moreover, we find that there is no simple
relative ordering between 1-norm geometric quantum discord and quantum discord.
This result contradicts the information which provided in some papers.


title:
Comparison of quantum discord and local quantum uncertainty in a
  vertical quantum dot

abstract:
  In this paper, we consider quantum correlations (quantum discord and local
quantum uncertainty) in a vertical quantum dot. Their dependencies on magnetic
field and temperature are presented in detail. It is noticeable that, quantum
discord and local quantum uncertainty behavior is similar to a large extent. In
addition, the time evolution of quantum discord and local quantum uncertainty
under dephasing and amplitude damping channels is investigated. It has been
found that, for some Belldiagonal states quantum discord is invariant under
some decoherence in a finite time interval [Phys. Rev. Lett. 104, 200401
(2010)]. Also, our results show that quantum discord is invariant under
dephasing channel for a finite time interval in a vertical quantum dot, while
this phenomenon does not occurs for local quantum uncertainty case.


title: Black Hole solutions in a cosmological spacetime background

abstract:
  We propose and analyze a new metric that has two conformal factors a(t) and
b(t) that combine the expansion of the universe and its effects on the spatial
and temporal part of the Schwarzschild metric in isotropic coordinates. We
present the solutions, their descriptions and we comment on their shortcomings.
In the spatially flat case of an expanding universe, we derive from the
proposed metric the special solutions of the field equations for the dust
approximation and the McVittie metric. We show that the presence of a black
hole does not modify the a(t) proportional to t^{2/3} law for dust and
H=constant for dark energy.


title: Doubly transitive groups and cyclic quandles

abstract:
  We prove that for n>2 there exists a quandle of cyclic type of size n if and
only if n is a power of a prime number. This establishes a conjecture of S.
Kamada, H. Tamaru and K. Wada. As a corollary, every finite quandle of cyclic
type is an Alexander quandle. We also prove that finite doubly transitive
quandles are of cyclic type. This establishes a conjecture of H. Tamaru.


title: Various Views on the Trapdoor Channel and an Upper Bound on its Capacity

abstract:
  Two novel views are presented on the trapdoor channel. First, by deriving the
underlying iterated function system (IFS), it is shown that the trapdoor
channel with input blocks of length $n$ can be regarded as the $n$th element of
a sequence of shapes approximating a fractal. Second, an algorithm is presented
that fully characterizes the trapdoor channel and resembles the recursion of
generating all permutations of a given string. Subsequently, the problem of
maximizing a $n$-letter mutual information is considered. It is shown that
$\frac{1}{2}\log_2\left(\frac{5}{2}\right)\approx 0.6610$ bits per use is an
upper bound on the capacity of the trapdoor channel. This upper bound, which is
the tightest upper bound known proves that feedback increases capacity of the
trapdoor channel.


title:
Investigation of the Quantum Correlations for a S=1/2 Ising- Heisenberg
  Model on a Symmetrical Diamond Chain

abstract:
  We consider the quantum correlations for a S=1/2 Ising- Heisenberg model of a
symmetrical diamond chain. Firstly, we compare concurrence, quantum discord and
1- norm geometric quantum discord of an ideal diamond chain in the absence of
magnetic field. The results show no simple ordering relations between these
quantum correlations, so that quantum discord may be smaller or larger than the
1-norm geometric quantum discord, which this observation contradict the
previous result that provided by F. M. Paula [1]. Symmetrical behavior of
quantum correlation versus ferromagnetic and anti- ferromagnetic coupling
constant J is considerable. The effect of external magnetic field H and
temperature- dependence is also considered. Furthermore, we study quantum
discord and geometric measure of quantum discord with the effect of next
nearest neighbor interaction between nodal Ising sites for a generalized
diamond chain, and we observe coexistence of phases with different values of
magnetic field for quantum correlations. Moreover, entanglement sudden death
occurs while quantum discord, 1- norm geometric quantum discord and geometric
quantum discord are immune from sudden death.


title:
Large Deviations for Weighted Sums of Stretched Exponential Random
  Variables

abstract:
  We consider the probability that a weighted sum of $n$ i.i.d. random
variables $X_j$, $j = 1, . . ., n$, with stretched exponential tails is larger
than its expectation and determine the rate of its decay, under suitable
conditions on the weights. We show that the decay is subexponential, and
identify the rate function in terms of the tails of $X_j$ and the weights. Our
result generalizes the large deviation principle given by Kiesel and
Stadtm\"uller [8] as well as the tail asymptotics for sums of i.i.d. random
variables provided by Nagaev [10, 11]. As an application of our result,
motivated by random projections of high-dimensional vectors, we consider the
case of random, self-normalized weights that are independent of the sequence
$\{X_j\}_{j \in \mathbb N}$, identify the decay rate for both the quenched and
annealed large deviations in this case, and show that they coincide. As another
example we consider weights derived from kernel functions that arise in
non-parametric regression.


title: XTribe: a web-based social computation platform

abstract:
  In the last few years the Web has progressively acquired the status of an
infrastructure for social computation that allows researchers to coordinate the
cognitive abilities of human agents in on-line communities so to steer the
collective user activity towards predefined goals. This general trend is also
triggering the adoption of web-games as a very interesting laboratory to run
experiments in the social sciences and whenever the contribution of human
beings is crucially required for research purposes. Nowadays, while the number
of on-line users has been steadily growing, there is still a need of
systematization in the approach to the web as a laboratory. In this paper we
present Experimental Tribe (XTribe in short), a novel general purpose web-based
platform for web-gaming and social computation. Ready to use and already
operational, XTribe aims at drastically reducing the effort required to develop
and run web experiments. XTribe has been designed to speed up the
implementation of those general aspects of web experiments that are independent
of the specific experiment content. For example, XTribe takes care of user
management by handling their registration and profiles and in case of
multi-player games, it provides the necessary user grouping functionalities.
XTribe also provides communication facilities to easily achieve both
bidirectional and asynchronous communication. From a practical point of view,
researchers are left with the only task of designing and implementing the game
interface and logic of their experiment, on which they maintain full control.
Moreover, XTribe acts as a repository of different scientific experiments, thus
realizing a sort of showcase that stimulates users' curiosity, enhances their
participation, and helps researchers in recruiting volunteers.


title:
Poisson equations, higher derivative automorphic forms and string
  parameter limits

abstract:
  This paper considers the higher derivative terms in the effective action of
type II string theory and in particular the behaviour of the automorphic forms
they contain in all the different possible limits of the string parameters. The
automorphic forms are thought to obey Poisson equations which contain the
Laplacian defined on the coset space to which the scalars fields belong and we
compute this Laplacian in all the possible string theory limits. We also
consider these Poisson equations in the decompactification limit of a single
dimension and by making two assumptions, one on the generic form of this
equation and the other on the behaviour of the automorphic forms in this limit,
we find strong constraints on the allowed form of this differential equation.
We show that these constraints allow one to recover much of what was previously
known about the automorphic forms corresponding to terms in the effective
action that have fourteen or fewer space-time derivatives in a simple way.