title: Broad absorption features in wind-dominated ULXs?

abstract:
  The luminosities of ultraluminous X-ray sources (ULXs) require an exotic
solution with either super-critical accretion modes onto stellar mass black
holes or sub-critical accretion onto intermediate mass black holes (IMBHs)
being invoked. Discriminating between the two is non-trivial due to the present
lack of a direct mass measurement. A key expectation of the super-critical mode
of accretion is the presence of powerful radiatively-driven winds. Here we
analyse XMM-Newton data from NGC 5408 X-1 and NGC 6946 X-1 and find that strong
soft residuals present in the X-ray spectra can be reconciled with broadened,
blue-shifted absorption by a partially ionised, optically thin phase of this
wind. We derive initial values for the physical parameters of the wind; we also
discuss other possible origins for the observed features.


title:
Production of Strange, Non-strange particles and Hypernuclei in an
  Excluded-Volume Model

abstract:
  We present a systematic study of production of strange and non-strange hadron
yields and their ratios obtained in various experiments using our
thermodynamically consistent excluded-volume model. We also analyze the
production of light nuclei, hypernuclei and their antinuclei in terms of our
excluded-volume model over a broad energy range starting from Alternating
Gradient Synchrotron (AGS) to Large Hadron Collider (LHC) energies. Further, we
extend our model for studying rapidity spectra of hadrons produced in heavy-ion
collisions.


title:
Interacting modified holographic Ricci dark energy model and statefinder
  diagnosis in flat universe

abstract:
  In this work we have considered the modified holographic Ricci dark energy
interacting with dark matter through a non-gravitational coupling. We took
three phenomenological forms for the interaction term $Q$ in the model, where
in general $Q$ is proportional to the Hubble parameter and densities of the
dark sectors, $\rho_{de}+\rho_m, \, \rho_m$ and $\rho_{de}$ respectively. We
have obtained analytical solutions for the three interacting models, and
studied the evolutions of equations of state parameter, deceleration parameter.
The results are compared with the observationally constrained values for the
best parameters of the model. We have also done the statefinder analysis of the
model to discriminate the model from other standard models. In general we have
shown that the model is showing a de Sitter type behavior in the far future of
the evolution of the universe.


title: Analytic uniquely ergodic volume preserving maps on odd spheres

abstract:
  We construct examples of volume-preserving uniquely ergodic (and hence
minimal) real-analytic diffeomorphisms on odd-dimemsional spheres


title:
Gravitational interactions between globular and open clusters: an
  introduction

abstract:
  Historically, it has been assumed that globular and open clusters never
interact. However, recent evidence suggests that: globular clusters passing
through the disk may be able to perturb giant molecular clouds (GMCs)
triggering formation of open clusters and some old open clusters may be linked
to accreted globulars. Here, we further explore the existence of possible
dynamical connections between globular and open clusters, and realize that the
most obvious link must be in the form of gravitational interactions. If open
clusters are born out of GMCs, they have to move in similar orbits. If we
accept that globulars can interact with GMCs, triggering star formation, it
follows that globular and open clusters must also interact. Consistently,
theoretical arguments as well as observational evidence, show that globular and
open clusters certainly are interacting populations and their interactions are
far more common than usually thought, especially for objects part of the
bulge/disk. Monte Carlo calculations confirm that conclusion. Globular clusters
seem capable of not only inducing formation of open clusters but, more often,
their demise. Relatively frequent high speed cluster encounters or cluster
harassment may also cause, on the long-term, slow erosion and tidal truncation
on the globulars involved. The disputed object FSR 1767 (2MASS-GC04) may be,
statistically speaking, the best example of an ongoing interaction.


title:
Exploiting Interference for Efficient Distributed Computation in
  Cluster-based Wireless Sensor Networks

abstract:
  This invited paper presents some novel ideas on how to enhance the
performance of consensus algorithms in distributed wireless sensor networks,
when communication costs are considered. Of particular interest are consensus
algorithms that exploit the broadcast property of the wireless channel to boost
the performance in terms of convergence speeds. To this end, we propose a novel
clustering based consensus algorithm that exploits interference for
computation, while reducing the energy consumption in the network. The
resulting optimization problem is a semidefinite program, which can be solved
offline prior to system startup.


title: MSSM Higgs Self-Couplings: Two-Loop O(alpha_t alpha_s) Corrections

abstract:
  We analyze the minimal supersymmetric Higgs self-couplings at O(alpha_t
alpha_s) within the effective potential approach. The two-loop corrections turn
out to be of moderate size in the DRbar scheme if the central scale is chosen
as half the SUSY scale. The inclusion of the two-loop corrections reduces the
renormalization scale dependence to the per-cent level. These results have a
significant impact on measurements of the trilinear Higgs self-couplings at the
LHC and a future e^+e^- collider.


title: A Method for Driving an Oscillator at a Quasi-Uniform Velocity

abstract:
  We describe a simple way to drive an actuator, comprising a superconducting
coil moving in a static magnetic field, at a quasi-uniform velocity. The main
objective is to avoid oscillations in this system with low damping, as they
undermine the uniformity of the velocity. The method consists in calculating
the force that should be exerted on the coil from the equation of motion and
programming a waveform generator to produce the corresponding current through
the coil. The method was tested on a device towing a grid through a closely
fitted channel filled with superfluid 4He at temperatures below 100 mK. The
motion of the grid over the distance of 4.3 cm at 10 cm/s resulted in
oscillations of less than 50 {\mu}m in amplitude (or less than 1 mm/s in terms
of velocity). The method can be applied to any oscillator.


title:
Emission line diagnostics for accretion and outflows in young very
  low-mass stars and brown dwarfs

abstract:
  We discuss accretion and outflow properties of three very low-mass young
stellar objects based on broad-band mid-resolution X-Shooter/VLT spectra. Our
targets (FU TauA, 2M 1207-39, and Par-Lup3-4) have spectral types between M5
and M8, ages between 1 Myr and ~10 Myr, and are known to be accreting from
previous studies. The final objective of our project is the determination of
mass outflow to accretion rate for objects near or within the substellar regime
as a probe for the T Tauri phase of brown dwarfs and the investigation of
variability in the accretion and outflow processes.


title: Analytical Model of an Isolated Single-atom Electron Source

abstract:
  An analytical model of a single-atom electron source is presented, where
electrons are created by near-threshold photoionization of an isolated atom.
The model considers the classical dynamics of the electron just after the
photon absorption, i.e. its motion in the potential of a singly charged ion and
a uniform electric field used for acceleration. From closed expressions for the
asymptotic transverse electron velocities and trajectories, the effective
source temperature and the effective source size can be calculated. The
influence of the acceleration field strength and the ionization laser energy on
these properties has been studied. With this model, a single-atom electron
source with the optimum electron beam properties can be designed. Furthermore,
we show that the model is also applicable to ionization of rubidium atoms, thus
also describes the ultracold electron source, which is based on photoionization
of laser-cooled alkali atoms.


title:
Path integral action of a particle in a magnetic field in the
  noncommutative plane and the Aharonov-Bohm effect

abstract:
  The formulation of noncommutative quantum mechanics as a quantum system
represented in the space of Hilbert-Schmidt operators is used to systematically
derive, using the standard time slicing procedure, the path integral action for
a particle moving in the noncommutative plane and in the presence of a magnetic
field and an arbitrary potential. Using this action, the equation of motion and
the ground state energy for the partcle are obtained explicitly. The
Aharonov-Bohm phase is derived using a variety of methods and several dualities
between this system and other commutative and noncommutative systems are
demonstrated. Finally, the equivalence of the path integral formulation with
the noncommutative Schr\"{o}dinger equation is also established.


title: Nonparametric identification of positive eigenfunctions

abstract:
  Important features of certain economic models may be revealed by studying
positive eigenfunctions of appropriately chosen linear operators. Examples
include long-run risk-return relationships in dynamic asset pricing models and
components of marginal utility in external habit formation models. This paper
provides identification conditions for positive eigenfunctions in nonparametric
models. Identification is achieved if the operator satisfies two mild
positivity conditions and a power compactness condition. Both existence and
identification are achieved under a further non-degeneracy condition. The
general results are applied to obtain new identification conditions for
external habit formation models and for positive eigenfunctions of pricing
operators in dynamic asset pricing models.


title: Further results on regular Fredholm pairs and chains

abstract:
  The main objective of the present article is to characterize regular Fredholm
pairs and chains in terms of Fredholm operators.


title:
Improved Stability Design of Interconnected Distributed Generation
  Resources

abstract:
  This work provides a design method for achieving a specified level of
stability for inverter-based interconnected distributed generation. The
stability of parallel connected distributed energy resources determined from a
linearized state-space model of the inverter dynamics that includes the
admittance matrix of the interconnecting distribution lines. Each inverter uses
a localized droop control scheme with the associated voltage and frequency
measurements obtained through the application of an enhanced phase locked loop.
Previous work on this topic has focused on single inverters connected to an
infinite bus without modeling of delays from a phase locked loop
implementation. This proposed method overcomes both of these limitations of
previous research. A detailed large-signal simulation of a three-bus
interconnected power system is analyzed under two different network admittance
values. Results confirm the effectiveness of the proposed stability design
method.


title: Temperature stratification of the atmosphere of Arcturus

abstract:
  A brief overview of the results of the investigations of the red giant star
Arcturus is given. One-dimensional LTE modeling of the atmospheres of Arcturus
and the Sun as a star is carried out on the basis of synthesis of the extended
wings of the H and K Ca II lines. It is found that the local continuum in this
spectral region is underestimated by an average of 12% in the atlases of
Arcturus. The average deficit in UV absorption amounts to 43% for Arcturus
whereas it is 9% for the Sun. For Arcturus the correction factor to the
continuum opacity at the wavelengths of 390.0, 392.5, 395.0, 398.0, and 400.0
nm equals 2.20, 1.90, 1.70, 1.55, and 1.45. The model atmosphere of Arcturus
obtained from the best-fit of the wings of the H and K Ca II lines corresponds
to the model atmosphere with the fundamental parameters T_eff = 4286 K, log g =
1.66, and [Fe/H]=-0.52 derived by Ramirez and Allende Prieto (2011). The
temperature stratification of Arcturus' atmosphere is presented in tabular
form. To obtain more accurate temperature stratification in the future, we need
a high spectral resolution spectrum calibrated to absolute fluxes with high
accuracy.


title:
Nonlinear undulator tapering in conventional SASE regime at baseline
  electron beam parameters as a way to optimize the radiation characteristics
  of the European XFEL

abstract:
  We demonstrate that the output radiation characteristics of the European XFEL
sources at nominal operation point can be easily made significantly better than
what is currently reported in the TDRs of scientific instruments and X-ray
optics. In fact, the output SASE characteristics of the baseline European XFEL
have been previously optimized assuming uniform undulators at a nominal
operating point of 5 kA peak current, without considering the potential of
udulator tapering in the SASE regime. In order to illustrate this point, we
analyze the case of an electron bunch with nominal parameters. Based on
start-to-end simulations, we demonstrate that nonlinear undulator tapering
allows one to achieve up to a tenfold increase in peak power and photon
spectral density in the conventional SASE regime, without modification to the
baseline design. The FEL code Genesis has been extensively used for these
studies. In order to increase our confidence in simulation results, we
cross-checked outcomes by reproducing simulations in the deep nonlinear SASE
regime with tapered undulator using the code ALICE.


title:
How (Not) to Shoot in Your Foot with SDN Local Fast Failover: A
  Load-Connectivity Tradeoff

abstract:
  This paper studies the resilient routing and (in-band) fast failover
mechanisms supported in Software-Defined Networks (SDN). We analyze the
potential benefits and limitations of such failover mechanisms, and focus on
two main metrics: (1) correctness (in terms of connectivity and loop-freeness)
and (2) load-balancing. We make the following contributions. First, we show
that in the worst-case (i.e., under adversarial link failures), the usefulness
of local failover is rather limited: already a small number of failures will
violate connectivity properties under any fast failover policy, even though the
underlying substrate network remains highly connected. We then present
randomized and deterministic algorithms to compute resilient forwarding sets;
these algorithms achieve an almost optimal tradeoff. Our worst-case analysis is
complemented with a simulation study.


title:
Distributed privacy-preserving network size computation: A
  system-identification based method

abstract:
  In this study, we propose an algorithm for computing the network size of
communicating agents. The algorithm is distributed: a) it does not require a
leader selection; b) it only requires local exchange of information, and; c)
its design can be implemented using local information only, without any global
information about the network. It is privacy-preserving, namely it does not
require to propagate identifying labels. This algorithm is based on system
identification, and more precisely on the identification of the order of a
suitably-constructed discrete-time linear time-invariant system over some
finite field. We provide a probabilistic guarantee for any randomly picked node
to correctly compute the number of nodes in the network. Moreover, numerical
implementation has been taken into account to make the algorithm applicable to
networks of hundreds of nodes, and therefore make the algorithm applicable in
real-world sensor or robotic networks. We finally illustrate our results in
simulation and conclude the paper with discussions on how our technique differs
from a previously-known strategy based on statistical inference.


title:
A Transformation Method to Construct Family of Exactly Solvable
  Potentials in Quantum Mechanics

abstract:
  A transformation method is applied to the second order ordinary differential
equation satisfied by orthogonal polynomials to construct a family of exactly
solvable quantum systems in any arbitrary dimensional space. Using the
properties of orthogonal polynomials, the method transforms polynomial
differential equation to D-dimensional radial Schrodinger equation which
facilitates construction of exactly solvable quantum systems. The method is
also applied using associated Laguerre and Hypergeometric polynomials. The
quantum systems generated from other polynomials are also briefly highlighted.


title: State-space approach to zero-modules of proper transfer functions

abstract:
  The poles and zeros of a transfer function can be studied by various means.
The main motivation of the present paper is to give a state-space description
of the module theoretic definition of zeros introduced and analyzed by Wyman et
al. (1989, 1991). This analysis is carried out for proper transfer functions.
  The obtained explicit equations determined by the system matrices are used
for defining two inner functions to transform the original transfer function
into a square, invertible one via multiplication eliminating the "generic"
zeros corresponding to the kernel and the image of the transfer function.
  As it is well-known the zeros are connected to various invariant subspaces
arising in geometric control, see e.g. Aling and Schumacher (1984) for a
complete description. The connections to these subspaces are also mentioned in
the paper.


title: Rapidly varying A-type stars in the SuperWASP archive

abstract:
  The searches for transiting exoplanets have produced a vast amount of
time-resolved photometric data of many millions of stars. One of the leading
ground-based surveys is the SuperWASP project. We present the initial results
of a survey of over 1.5 million A-type stars in the search for high frequency
pulsations using SuperWASP photometry. We are able to detect pulsations down to
the 0.5 mmag level in the broad-band photometry. This has enabled the discovery
of several rapidly oscillating Ap stars and over 200 delta Scuti stars with
frequencies above 50 d$^{-1}$, and at least one pulsating sdB star. Such a
large number of results allows us to statistically study the frequency overlap
between roAp and delta Scuti stars and probe to higher frequency regimes with
existing data.


title:
A Physically-Intuitive Method for Calculation of the Local Lattice
  Constant from a High-Resolution Transmission Electron Microscopy Image by
  Fourier Analysis

abstract:
  We have developed a physically-intuitive method to calculate the local
lattice constant as a function of position in a high-resolution transmission
electron microscopy image by performing a two-dimensional fast Fourier
transform. We apply a Gaussian filter with appropriate spatial
full-width-half-max (FWHM) bandwidth to the image centered at the desired
location to calculate the local lattice constant (as opposed to the average
lattice constant). Fourier analysis of the filtered image yields the vertical
and horizontal lattice constants at this location. The process is repeated by
stepping the Gaussian filter across the image to produce a set of local lattice
constants in the vertical and horizontal direction as a function of position in
the image. The method has been implemented in a freely available tool on
nanoHUB.


title: Freeform high-speed large-amplitude deformable Piezo Mirrors

abstract:
  We present a new type of tunable mirror with sharply-featured freeform
displacement profiles, large displacements of several 100\mu m and high
operating frequencies close to the kHz range at 15mm diameter. The actuation
principle is based on a recently explored "topological" displacement mode of
piezo sheets. The prototypes presented here include a rotationally symmetric
axicon, a hyperbolic sech-icon and a non-symmetric pyram-icon and are scalable
to smaller dimensions. The fabrication process is economic and cleanroom-free,
and the optical quality is sufficient to demonstrate the diffraction patterns
of the optical elements.


title: Focusing Mirror with Tunable Eccentricity

abstract:
  We present a new kind of varifocal mirror with independently adjustable
curvatures in the major directions. For actuation we use two stacked piezo
bending actuators with crossed in-plane polarization. This mirror can be used
for example as an off-axis focusing device with tunable focal length and
compensation for a variable angle of incidence or for coma correction. We
demonstrate the prototype of such a mirror and characterize the mechanical
deflection, as well as the focusing capabilities.


title:
Boundary Regularity Criteria for the 6D Steady Navier-Stokes and MHD
  Equations

abstract:
  It is shown in this paper that suitable weak solutions to the 6D steady
incompressible Navier-Stokes and MHD equations are H\"older continuous near
boundary provided that either $r^{-3}\int_{B_r^+}|u(x)|^3dx$ or
$r^{-2}\int_{B_r^+}|\nabla u(x)|^2dx$ is sufficiently small, which implies that
the 2D Hausdorff measure of the set of singular points near the boundary is
zero. This generalizes recent interior regularity results by Dong-Strain
\cite{DS}.


title:
Relativistic bands in the spectrum of created particles via dynamical
  Casimir effect

abstract:
  We present a general analytical approach to investigate relativistic
corrections in the dynamical Casimir effect (DCE). Particularly, we discuss the
behavior of the additional frequency bands that appear in the spectral
distribution of the created particles when the first relativistic corrections
are taken into account. We do that in the context of circuit QED, by analyzing
the setup used in the first measurement of the DCE, where a system with a
time-dependent boundary condition simulates the mechanical motion of a single
mirror in 1+1 dimensions. Our method is applicable to a large class of systems
with oscillatory time-dependent parameters and can be generalized to higher
dimensions and other fields.


title: On the second fluctuation--dissipation theorem for nonequilibrium baths

abstract:
  Baths produce friction and random forcing on particles suspended in them. The
relation between noise and friction in (generalized) Langevin equations is
usually referred to as the second fluctuation-dissipation theorem. We show what
is the proper nonequilibrium extension, to be applied when the environment is
itself active and driven. In particular we determine the effective Langevin
dynamics of a probe from integrating out a steady nonequilibrium environment.
The friction kernel picks up a frenetic contribution, i.e., involving the
environment's dynamical activity, responsible for the breaking of the standard
Einstein relation.


title:
Angular dependence of magnetoresistance in strongly anisotropic
  quasi-two-dimensional metals for various Landau-level shapes

abstract:
  We present the quantum-mechanical calculations of the angular dependence of
interlayer conductivity $\sigma _{zz}(\theta )$ in a tilted magnetic field in
quasi-2D layered metals. Our calculation shows that the LL shape is important
for this angular dependence. In particular, the amplitude of angular
magnetoresistance oscillations (AMRO) is much stronger for the Gaussian LL
shape than for the Lorentzian. The ratio $\sigma_{zz}(\theta =0)/
\sigma_{zz}(\theta ->\pm 90^{\circ})$ is also several times larger for the
Gaussian LL shape. AMRO and Zeeman energy splitting lead to a spin current. For
typical organic metals and for a medium magnetic field 10T this spin current is
only a few percent of the charge current, but its value may almost reach the
charge current for special tilt angles of magnetic field. The spin current has
strong angular oscillations, which are phase-shifted as compared to the usual
AMRO.


title: Generalized quasi-dilaton theory

abstract:
  Recently the first example of a unitary theory of Lorentz-invariant massive
gravity allowing for stable self-accelerating de Sitter solutions was found,
extending the quasidilaton theory. In this paper we further generalize this new
action for the quasidilaton field by introducing general Lagrangian terms which
are consistent with the quasidilaton symmetry while leading to second order
equations of motion. We find that the structure of the theory, compared to the
simplest stable example, does not change on introducing these new terms.


title: Nonlinearity enhanced interfacial thermal conductance and rectification

abstract:
  We study the nonlinear interfacial thermal transport across atomic junctions
by the quantum self-consistent mean field (QSCMF) theory based on
nonequilibrium Green's function approach; the QSCMF theory we propose is very
precise and matches well with the exact results from quantum master equations.
The nonlinearity at the interface is studied by effective temperature dependent
interfacial coupling calculated from the QSCMF theory. We find that
nonlinearity can provide an extra channel for phonon transport in addition to
the phonon scattering which usually blocks heat transfer. For weak linearly
coupled interface, the nonlinearity can enhance the interfacial thermal
transport; with increasing nonlinearity or temperature, the thermal conductance
shows nonmonotonical behavior. The interfacial nonlinearity also induces
thermal rectification, which depends on the mismatch of the two leads and also
the interfacial linear coupling.

categories: cond-mat.stat-mech cond-mat.mes-hall cond-mat.mtrl-sci quant-ph


title: Total Thue colourings of graphs

abstract:
  A total colouring of a graph is a colouring of its vertices and edges such
that no two adjacent vertices or edges have the same colour and moreover, no
edge coloured $c$ has its endvertex coloured $c$ too. A weak total Thue
colouring of a graph $G$ is a colouring of its vertices and edges such that the
colour sequence of consecutive vertices and edges of every path of $G$ is
nonrepetitive. In a total Thue colouring also the induced vertex-colouring and
edge-colouring of $G$ are nonrepetitive. The weak total Thue number
$\pi_{T_w}(G)$ of a graph $G$ denotes the minimum number of colours required in
every weak total Thue colouring and the minimum number of colours required in
every total Thue colouring is called the total Thue number $\pi_T$. Here we
show some upper bounds for both parameters depending on the maximum degree or
size of the graph. We also give some lower bounds and some better upper bounds
for these graph parameters considering special families of graphs.


title: Strong cylindricality and the monodromy of bundles

abstract:
  A surface $F$ in a 3-manifold $M$ is called cylindrical if $M$ cut open along
$F$ admits an essential annulus $A$. If, in addition, $(A, \partial A)$ is
embedded in $(M, F)$, then we say that $F$ is strongly cylindrical. Let $M$ be
a connected 3-manifold that admits a triangulation using $t$ tetrahedra and $F$
a two-sided connected essential closed surface of genus $g(F)$. We show that if
$g(F)$ is at least $38 t$, then $F$ is strongly cylindrical. As a corollary, we
give an alternative proof of the assertion that every closed hyperbolic
3-manifold admits only finitely many fibrations over the circle with connected
fiber whose translation distance is not one, which was originally proved by
Saul Schleimer.


title:
Thermal transport across metal-insulator interface via electron-phonon
  interaction

abstract:
  The thermal transport across metal-insulator interface can be characterized
by electron-phonon interaction through which an electron lead is coupled to a
phonon lead if phonon-phonon coupling at the interface is very weak. We
investigate the thermal conductance and rectification flowing between the
electron part and the phonon part using nonequilibrium Green's function method.
It is found that the thermal conductance has a nonmonotonic behavior as a
function of average temperature or the coupling strength between the phonon
leads in the metal part and the insulator one. The metal-insulator interface
shows evident thermal rectification effect, which can reverse with changing of
average temperature or the electron-phonon coupling.


title: Co-prolongations of a group extension

abstract:
  The aim of this paper is to study co-prolongations of central extensions. We
construct the obstruction theory for co-prolongations and classify the
equivalence classes of these by kernels of a homomorphisms between
2-dimensional cohomology groups of groups.


title: Nucleon structure and hard p-p processes at high energies

abstract:
  The production of heavy flavour hadrons in $pp$ collisions at large values of
their transverse momenta can be a new unique source for estimation of intrinsic
heavy quark contribution to the proton. We analyze the inclusive production of
the open strangeness and the semi-inclusive hard processes of the photon and
vector boson production accompanied by the $c$- or $b$-jets in $pp$ collisions.
We show that one should select the parton-level (sub)processes (and final-state
signatures) that are the most sensitive to the intrinsic heavy quark
contributions. We present some predictions for these processes made within the
perturbative QCD including the intrinsic strangeness and intrinsic charm in the
proton that can be verified in the NA61 experiment and at LHC.


title:
Exit laws from large balls of (an)isotropic random walks in random
  environment

abstract:
  We study exit laws from large balls in $\mathbb{Z}^d$, $d\geq3$, of random
walks in an i.i.d. random environment that is a small perturbation of the
environment corresponding to simple random walk. Under a centering condition on
the measure governing the environment, we prove that the exit laws are close to
those of a symmetric random walk, which we identify as a perturbed simple
random walk. We obtain bounds on total variation distances as well as local
results comparing exit probabilities on boundary segments. As an application,
we prove transience of the random walks in random environment. Our work
includes the results on isotropic random walks in random environment of
Bolthausen and Zeitouni [Probab. Theory Related Fields 138 (2007) 581-645].
Since several proofs in Bolthausen and Zeitouni (2007) were incomplete, a
somewhat different approach was given in the first author's thesis [Long-time
behavior of random walks in random environment (2013) Z\"{u}rich Univ.]. Here,
we extend this approach to certain anisotropic walks and provide a further step
towards a fully perturbative theory of random walks in random environment.


title: Sym-Bobenko formula for minimal surfaces in Heisenberg space

abstract:
  We give an immersion formula, the Sym-Bobenko formula, for minimal surfaces
in the 3-dimensional Heisenberg space. Such a formula can be used to give a
generalized Weierstrass type representation and construct explicit examples of
minimal surfaces.


title:
Piezo films with adjustable anisotropic strain for bending actuators
  with tunable bending profiles

abstract:
  We present a method to produce in-plane polarized piezo films with a freely
adjustable ratio of the strains in orthogonal in-plane directions. They can be
used in piezo bending actuators with a tunable curvature profile. The strains
are obtained as mean strains from a periodic polarization pattern produced by a
suitable doubly interdigitated electrode structure. This mechanism is
demonstrated for several examples using PZT sheets. We further discuss how this
tuning and the parameters of the electrode layout affect the overall magnitude
of the displacement.


title:
3-Cocycles, Non-Associative Star-Products and the Magnetic Paradigm of
  R-Flux String Vacua

abstract:
  We consider the geometric and non-geometric faces of closed string vacua
arising by T-duality from principal torus bundles with constant H-flux and pay
attention to their double phase space description encompassing all toroidal
coordinates, momenta and their dual on equal footing. We construct a
star-product algebra on functions in phase space that is manifestly duality
invariant and substitutes for canonical quantization. The 3-cocycles of the
Abelian group of translations in double phase space are seen to account for
non-associativity of the star-product. We also provide alternative
cohomological descriptions of non-associativity and draw analogies with the
quantization of point-particles in the field of a Dirac monopole or other
distributions of magnetic charge. The magnetic field analogue of the R-flux
string model is provided by a constant uniform distribution of magnetic charge
in space and non-associativity manifests as breaking of angular symmetry. The
Poincare vector comes to rescue angular symmetry as well as associativity and
also allow for quantization in terms of operators and Hilbert space only in the
case of charged particles moving in the field of a single magnetic monopole.


title: Low Complexity List Successive Cancellation Decoding of Polar Codes

abstract:
  We propose a low complexity list successive cancellation (LCLSC) decoding
algorithm to reduce complexity of traditional list successive cancellation
(LSC) decoding of polar codes while trying to maintain the LSC decoding
performance at the same time. By defining two thresholds, namely "likelihood
ratio (LR) threshold" and "Bhattacharyya parameter threshold", we classify the
reliability of each received information bit and the quality of each bit
channel. Based on this classification, we implement successive cancellation
(SC) decoding instead of LSC decoding when the information bits from "bad"
subchannels are received reliably and further attempt to skip LSC decoding for
the rest information bits in order to achieve a lower complexity compared to
full LSC decoding. Simulation results show that the complexity of LCLSC
decoding is much lower than LSC decoding and can be close to that of SC
decoding, especially in low code rate regions.


title:
The spectral catalogue of INTEGRAL gamma-ray bursts: results of the
  joint IBIS/SPI spectral analysis

abstract:
  We present the updated INTEGRAL catalogue of gamma-ray bursts (GRBs) observed
between December 2002 and February 2012. The catalogue contains the spectral
parameters for 59 GRBs localized by the INTEGRAL Burst Alert System (IBAS). We
used the data from the two main instruments on board the INTEGRAL satellite:
the spectrometer SPI (SPectrometer on INTEGRAL) nominally covering the energy
range 18 keV - 8 MeV, and the imager IBIS (the Imager on Board the INTEGRAL
Satellite) operating in the range from 15 keV to 10 MeV. For the spectral
analysis we applied a new data extraction technique, developed in order to
explore the energy regions of highest sensitivity for both instruments, SPI and
IBIS. It allowed us to perform analysis of the GRB spectra over a broad energy
range and to determine the bursts' spectral peak energies. The spectral
analysis was performed on the whole sample of GRBs triggered by IBAS, including
all the events observed in period December 2002 - February 2012. The catalogue
contains the trigger times, burst coordinates, positional errors, durations and
peak fluxes for 28 unpublished GRBs observed between September 2008 and
February 2012. The light curves in 20 - 200 keV energy band of these events
were derived using IBIS data. We compare the prompt emission properties of the
INTEGRAL GRB sample with the BATSE and Fermi samples.


title: Reconstructing the environment seen by a RWRE

abstract:
  Consider a walker performing a random walk in an i.i.d. random environment,
and assume that the walker tells us at each time the environment it sees at its
present location. Given this history of the transition probabilities seen from
the walker - but not its trajectory - can we tell if the RWRE is recurrent or
transient? Can we reconstruct the law of the environment? We show that in a
one-dimensional environment, the law of the environment can be reconstructed,
and we know in particular if the RWRE is recurrent or transient.


title: A Novel Approach to Study Atmospheric Neutrino Oscillation

abstract:
  We develop a general theoretical framework to analytically disentangle the
contributions of the neutrino mass hierarchy, the atmospheric mixing angle, and
the CP phase, in neutrino oscillations. To illustrate the usefulness of this
framework, especially that it can serve as a complementary tool to neutrino
oscillogram in the study of atmospheric neutrino oscillations, we take PINGU as
an example and compute muon- and electron-like event rates with event cuts on
neutrino energy and zenith angle. Under the assumption of exact momentum
measurements of neutrinos with a perfect e-$\mu$ identification and no
backgrounds, we find that the PINGU experiment has the potential of resolving
the neutrino mass hierarchy and the octant degeneracies within 1-year run,
while the measurement of the CP phase is significantly more challenging. Our
observation merits a serious study of the detector capability of estimating the
neutrino momentum for both muon- and electron-like events.


title: A supersimple analysis of $e^-e^+\to W^- W^+$ at high energy

abstract:
  Studying $e^-e^+\to W^- W^+$ at the 1loop electroweak (EW) order, we derive
very accurate and simple expressions for the four Helicity Conserving (HC)
amplitudes, which dominate this process at high energies. The calculations are
done in both, the SM and MSSM frameworks. Such expressions, called supersimple
(sim), nicely emphasize the dynamical contents of each framework. Numerical
illustrations are presented, which show the accuracy of this description, and
how it can be used for identifying possible additional new physics
contributions; like e.g. Anomalous Gauge Couplings (AGC) or a new $Z'$ vector
boson exchange. The procedure is useful even if only SM is visible at the
future Linear Collider energies.


title: The Hosoya polynomial of distance-regular graphs

abstract:
  In this note we obtain an explicit formula for the Hosoya polynomial of any
distance-regular graph in terms of its intersection array. As a consequence, we
obtain a very simple formula for the Hosoya polynomial of any strongly regular
graph.


title: Exact Solutions of a Fermion-Soliton System in Two Dimensions

abstract:
  We investigate a coupled system of a Dirac particle and a pseudoscalar field
in the form of a soliton in (1+1) dimensions and find some of its exact
solutions numerically.
  We solve the coupled set of equations self-consistently and
non-perturbatively by the use of a numerical method and obtain the bound states
of the fermion and the shape of the soliton. That is the shape of the static
soliton in this problem is not prescribed and is determined by the equations
themselves. This work goes beyond the perturbation theory in which the back
reaction of the fermion on soliton is its first order correction. We compare
our results to those of an exactly solvable model in which the soliton is
prescribed. We show that, as expected, the total energy of our system is lower
than the prescribed one. We also compute non-perturbatively the vacuum
polarization of the fermion induced by the presence of the soliton and display
the results. Moreover, we compute the soliton mass as a function of the boson
and fermion masses and find that the results are consistent with Skyrme's
phenomenological conjecture. Finally, we show that for fixed values of the
parameters, the shape of the soliton obtained from our exact solutions depends
slightly on the fermionic state to which it is coupled. However, the exact
shape of the soliton is always very close to the isolated kink.


title:
Demonstration of Experimental Three Dimensional Finite Time Lyapunov
  Exponents with Inertial Particles

abstract:
  This work provides an experimental method for simultaneously measuring finite
time Lyapunov exponent fields for multiple particle groups, including non-flow
tracers, in three-dimensional multiphase flows. From sequences of particle
images, e.g., from experimental fluid imaging techniques, we can directly
compute the flow map and coherent structures, with out performing the
computationally costly numerical integration. This is particularly useful to
find three-dimensional Lagrangian coherent structures for inertial particles,
that do not follow the bulk fluid velocity, as we demonstrate for a grid
turbulence experiment. The technique described may provide a new means for
exploring the physics of experimental multi-phase flows.


title:
PDR Model Mapping of Obscured H2 Emission and the Line-of-Sight
  Structure of M17-SW

abstract:
  We observed H2 line emission with Spitzer-IRS toward M17-SW and modeled the
data with our PDR code. Derived gas density values of up to few times 10^7
cm^-3 indicate that H2 emission originates in high-density clumps. We discover
that the PDR code can be utilized to map the amount of intervening extinction
obscuring the H2 emission layers, and thus we obtain the radial profile of A_V
relative to the central ionizing cluster NGC 6618. The extinction has a
positive radial gradient, varying between 15--47 mag over the projected
distance of 0.9--2.5 pc from the primary ionizer, CEN 1. These high extinction
values are in good agreement with previous studies of A_V toward stellar
targets in M17-SW. The ratio of data to PDR model values is used to infer the
global line-of-sight structure of the PDR surface, which is revealed to
resemble a concave surface relative to NGC 6618. Such a configuration confirms
that this PDR can be described as a bowl-shaped boundary of the central H II
region in M17. The derived structure and physical conditions are important for
interpreting the fine-structure and rotational line emission from the PDR.


title:
A new approach to simulation of limiting photoconversion efficiency of
  tandem solar cells

abstract:
  We develop a new approach to calculate the obtainable limit of
photoconversion efficiency of tandem solar cells (SCs) and applied it to SCs
with both vertical and lateral designs at AM0 and AM1.5 conditions. To get the
maximum efficiency, only radiative recombination has been considered using
typical radiative recombination parameters of the direct band gap III-V
semiconductors, and explicit energy dependence of light absorption. When
simulating the efficiency, we selfconsistently took into account the fact that
the amount of the heat dissipated by SC decreases as the number of
current-matched sub-cells increases. As the operating SCs temperature decreases
both the open-circuit voltage and the photoconversion efficiency increase. It
is shown that the above effect is especially strong for SCs operating under AM0
conditions. As the number of subcells is increased, narrowing the spectral
range for each subcell, the photocurrent is additionally reduced due to the
energy dependent light absorption, the factor generally ignored in the standard
approaches. Application of our formalism results in a maximum in the
theoretical dependence of the efficiency on the number of subcells, which was
indeed observed experimentally. Besides agreement with experiment, our
theoretical results are also close to other efficiencies calculated using
detailed balance based approaches.


title:
Singularity resolution by lattice shifts in discretised quantum
  mechanics

abstract:
  We investigate the robustness of singularity avoidance mechanisms in
nonrelativistic quantum mechanics on the discretised real line when lattice
points are allowed to approach a singularity of the classical potential. We
consider the attractive Coulomb potential and the attractive scale invariant
potential, on an equispaced parity-noninvariant lattice and on a non-equispaced
parity-invariant lattice, and we examine the energy eigenvalues by a
combination of analytic and numerical techniques. While the lowest one or two
eigenvalues descend to negative infinity in the singular limit, we find that
the higher eigenvalues remain finite and form degenerate pairs, close to the
eigenvalues of a theory in which a lattice point at the singularity is
regularised either by Thiemann's loop quantum gravity singularity avoidance
prescription or by a restriction to the odd parity sector. The approach to
degeneracy can be reproduced from a nonsingular discretised half-line quantum
theory by tuning a boundary condition parameter. The results show that
Thiemann's singularity avoidance prescription and the discretised half-line
boundary condition reproduce quantitatively correct features of the singular
limit spectrum apart from the lowest few eigenvalues.


title:
Thermodynamic Stability of Mg-based Ternary Long-Period Stacking Ordered
  Structures

abstract:
  Mg alloys containing long-period stacking ordered (LPSO) structures exhibit
remarkably high tensile yield strength and ductility. They have been found in a
variety of ternary Mg systems of the general form Mg-XL-XS, where XL and XS are
elements larger and smaller than Mg, respectively. In this work, we examine the
thermodynamic stability of these LPSO precipitates with density functional
theory, using a newly proposed structure model based on the inclusion of a Mg
interstitial atom. We predict the stabilities for 14H and 18R LPSO structures
for many Mg-XL-XS ternary systems: 85 systems consisting of XL=rare earths (RE)
Sc,Y,La-Lu and XS=Zn,Al,Cu,Co,Ni. We predict thermodynamically stable LPSO
phases in all systems where LPSO structures are observed. In addition, we
predict several stable LPSO structures in new, as-yet-unobserved Mg-RE-XS
systems. Many non-RE XL elements are also explored on the basis of size
mismatch between Mg and XL, including Tl,Sb,Pb,Na,Te,Bi,Pa,Ca,Th,K,Sr --- an
additional 55 ternary systems. XL=Ca, Sr, and Th are predicted to be most
promising to form stable LPSO phases, particularly with XS=Zn. Lastly, several
previously observed trends amongst known XL elements are examined. We find that
favorable mixing energy between Mg and XL on the FCC lattice and the size
mismatch together serve as excellent criteria determining XL LPSO formation.


title:
Structural control of magnetic anisotropy in a strain driven
  multiferroic EuTiO3 thin film

abstract:
  Octahedral distortion plays a key role in engineering the physical properties
of heterostructures composed of perovskite oxides. We observe a strong in-plane
uniaxial magnetic anisotropy in a strain-enabled multiferroic EuTiO3 thin film
epitaxially grown on a (110)o DyScO3 substrate. First principles calculations
show that the magnetic anisotropy is closely correlated with the uniaxial TiO6
octahedral tilting and the ferroelectric polarization of the film, indicating
potential strong magnetoelectric coupling in the strain-engineered multiferroic
system.


title: Double seesaw mechanism and lepton mixing

abstract:
  We present a general framework for models in which the lepton mixing matrix
is the product of the maximal mixing matrix U_\omega\ times a matrix
constrained by a well-defined Z_2 symmetry. Our framework relies on neither
supersymmetry nor non-renormalizable Lagrangians nor higher dimensions; it
relies instead on the double seesaw mechanism and on the soft breaking of
symmetries. The framework may be used to construct models for virtually all the
lepton mixing matrices of the type mentioned above which have been proposed in
the literature.


title: Cache Performance Study of Portfolio-Based Parallel CDCL SAT Solvers

abstract:
  Parallel SAT solvers are becoming mainstream. Their performance has made them
win the past two SAT competitions consecutively and are in the limelight of
research and industry. The problem is that it is not known exactly what is
needed to make them perform even better; that is, how to make them solve more
problems in less time. Also, it is also not know how well they scale in massive
multi-core environments which, predictably, is the scenario of comming new
hardware. In this paper we show that cache contention is a main culprit of a
slowing down in scalability, and provide empirical results that for some type
of searches, physically sharing the clause Database between threads is
beneficial.


title:
Novikov algebras and a classification of multicomponent Camassa-Holm
  equations

abstract:
  A class of multi-component integrable systems associated to Novikov algebras,
which interpolate between KdV and Camassa-Holm type equations, is obtained. The
construction is based on the classification of low-dimensional Novikov algebras
by Bai and Meng. These multi-component bi-Hamiltonian systems obtained by this
construction may be interpreted as Euler equations on the centrally extended
Lie algebras associated to the Novikov algebras. The related bilinear forms
generating cocycles of first, second and third order are classified. Several
examples, including known integrable equations, are presented.


title:
On the numerical solution of some nonlinear stochastic differential
  equations using the semi-discrete method

abstract:
  In this paper we are interested in the numerical solution of stochastic
differential equations with non negative solutions. Our goal is to construct
explicit numerical schemes that preserve positivity, even for super linear
stochastic differential equations. It is well known that the usual Euler scheme
diverges on super linear problems and the Tamed-Euler method does not preserve
positivity. In that direction, we use the Semi-Discrete method that the first
author has proposed in two previous papers. We propose a new numerical scheme
for a class of stochastic differential equations which are super linear with
non negative solution. In this class of stochastic differential equations
belongs the Heston $3/2$-model that appears in financial mathematics, for which
we prove %theoretically and through numerical experiments the "optimal" order
of strong convergence at least $1/2$ of the Semi-Discrete method.


title: A conjecture on Whittaker-Fourier coefficients of cusp forms

abstract:
  We formulate an analogue of the Ichino-Ikeda conjectures for the
Whittaker-Fourier coefficients of automorphic forms on quasi-split reductive
groups. This sharpens the conjectures of Sakellaridis-Venkatesh in the case at
hand.


title: Localised distributions in complex Langevin dynamics

abstract:
  Complex Langevin dynamics can be used to perform numerical simulations of
theories with a complex action. In order to justify the procedure, it is
important to understand the properties of the real and positive distribution,
which is effectively sampled during the stochastic process. In the context of a
simple model, we study this distribution and relate the results to the recently
derived criteria for correctness. We demonstrate analytically that if the
distribution has support only on a strip in the complexified configuration
space, correct results are expected.


title:
Light Sterile Neutrinos in Cosmology and Short-Baseline Oscillation
  Experiments

abstract:
  We analyze the most recent cosmological data, including Planck, taking into
account the possible existence of a sterile neutrino with a mass at the eV
scale indicated by short-baseline neutrino oscillations data in the 3+1
framework. We show that the contribution of local measurements of the Hubble
constant induces an increase of the value of the effective number of
relativistic degrees of freedom above the Standard Model value, giving an
indication in favor of the existence of sterile neutrinos and their
contribution to dark radiation. Furthermore, the measurements of the local
galaxy cluster mass distribution favor the existence of sterile neutrinos with
eV-scale masses, in agreement with short-baseline neutrino oscillations data.
In this case there is no tension between cosmological and short-baseline
neutrino oscillations data, but the contribution of the sterile neutrino to the
effective number of relativistic degrees of freedom is likely to be smaller
than one. Considering the Dodelson-Widrow and thermal models for the
statistical cosmological distribution of sterile neutrinos, we found that in
the Dodelson-Widrow model there is a slightly better compatibility between
cosmological and short-baseline neutrino oscillations data and the required
suppression of the production of sterile neutrinos in the early Universe is
slightly smaller.


title: SINR Diagram with Interference Cancellation

abstract:
  In this paper we study the reception zones of a wireless network in the SINR
model with receivers that employ \emph{interference cancellation} (IC), a
technique that allows a receiver to decode interfering signals, and
\emph{cancel} them from the received signal in order to decode its intended
message. We first derive some important topological properties of the diagram
describing the reception zones and their connections to \emph{high-order
Voronoi diagrams} and other related geometric objects. We then discuss the
computational issues that arise when seeking an efficient description of the
zones. Our main fundamental result states that although potentially there are
exponentially many possible cancellation orderings (and consequently reception
cells), in fact there are much fewer nonempty such cells. We prove a (tight)
linear bound on the number of cells and provide a polynomial time algorithm to
describe the diagram. Moreover, we introduce a novel measure, referred to as
the \emph{Compactness Parameter}, which influences the tightness of our bounds.
We then utilize the properties established for reception diagrams to devise a
logarithmic time algorithm for answering \emph{point-location} queries for
networks with IC.


title: Random-field-like criticality in glass-forming liquids

abstract:
  We introduce an approach to derive an effective scalar field theory for the
glass transition; the fluctuating field is the overlap between equilibrium
configurations. We apply it to the case of constrained liquids for which the
introduction of a conjugate source to the overlap field was predicted to lead
to an equilibrium critical point. We show that the long-distance physics in the
vicinity of this critical point is in the same universality class as that of a
paradigmatic disordered model: the random-field Ising model. The quenched
disorder is provided here by a reference equilibrium liquid configuration. We
discuss to what extent this field-theoretical description and the mapping to
the random field Ising model hold in the whole supercooled liquid regime, in
particular near the glass transition.


title: Improved LT Codes in Low Overhead Regions for Binary Erasure Channels

abstract:
  We study improved degree distribution for Luby Transform (LT) codes which
exhibits improved bit error rate performance particularly in low overhead
regions. We construct the degree distribution by modifying Robust Soliton
distribution. The performance of our proposed LT codes is evaluated and
compared to the conventional LT codes via And-Or tree analysis. Then we propose
a transmission scheme based on the proposed degree distribution to improve its
frame error rate in full recovery regions. Furthermore, the improved degree
distribution is applied to distributed multi-source relay networks and unequal
error protection. It is shown that our schemes achieve better performance and
reduced complexity especially in low overhead regions, compared with
conventional schemes.


title:
Dn Symmetric Hamiltonian System: A Network of Coupled Gyroscopes as a
  Case Study

abstract:
  The evolution of a large class of biological, physical and engineering
systems can be studied through both dynamical systems theory and Hamiltonian
mechanics. The former theory, in particular its specialization to study systems
with symmetry, is already well developed and has been used extensively on a
wide variety of spatio-temporal systems. There are, however, fewer results on
higher-dimensional Hamiltonian systems with symmetry. This lack of results has
lead us to investigate the role of symmetry, in particular dihedral symmetry,
on high-dimensional coupled Hamiltonian systems. As a representative example,
we consider the model equations of a ring of vibratory gyroscopes. The
equations are reformulated in a Hamiltonian structure and the corresponding
normal forms are derived. Through a normal form analysis, we investigated the
effects of various coupling schemes and unraveled the nature of the
bifurcations that lead the ring of gyroscopes into and out of synchronization.
The Hamiltonian approach is specially useful in investigating the collective
behavior of small and large ring sizes and it can be readily extended to other
symmetry-related systems.


title:
Inducing Honest Reporting Without Observing Outcomes: An Application to
  the Peer-Review Process

abstract:
  When eliciting opinions from a group of experts, traditional devices used to
promote honest reporting assume that there is an observable future outcome. In
practice, however, this assumption is not always reasonable. In this paper, we
propose a scoring method built on strictly proper scoring rules to induce
honest reporting without assuming observable outcomes. Our method provides
scores based on pairwise comparisons between the reports made by each pair of
experts in the group. For ease of exposition, we introduce our scoring method
by illustrating its application to the peer-review process. In order to do so,
we start by modeling the peer-review process using a Bayesian model where the
uncertainty regarding the quality of the manuscript is taken into account.
Thereafter, we introduce our scoring method to evaluate the reported reviews.
Under the assumptions that reviewers are Bayesian decision-makers and that they
cannot influence the reviews of other reviewers, we show that risk-neutral
reviewers strictly maximize their expected scores by honestly disclosing their
reviews. We also show how the group's scores can be used to find a consensual
review. Experimental results show that encouraging honest reporting through the
proposed scoring method creates more accurate reviews than the traditional
peer-review process.


title:
Low-energy interband transitions in the infrared response of
  Ba(Fe1-xCox)2As2

abstract:
  We studied the doping and temperature (T) dependence of the infrared (IR)
response of Ba(Fe1-xCox)2As2 single crystals. We show that a weak band around
1000 cm-1, that was previously interpreted in terms of interaction of the
charge carriers with magnetic excitations or of a pseudogap, is rather related
to low-energy interband transitions. Specifically, we show that this band
exhibits a similar doping and T-dependence as the hole pockets seen by angle
resolved photoemission spectroscopy (ARPES). Notably, we find that it vanishes
as a function of doping near the critical point where superconductivity is
suppressed in the overdoped regime. Our IR data thus provide bulk specific
information (complementary to the surface sensitive ARPES) for a Lifshitz
transition. Our IR data also reveal a second low-energy band around 2300 cm-1
which further emphasizes the necessity to consider the multiband nature of
these iron arsenides in the analysis of the optical response.


title: Observation of Pure Spin Transport in a Diamond Spin Wire

abstract:
  Spin transport electronics - spintronics - focuses on utilizing electron spin
as a state variable for quantum and classical information processing and
storage. Some insulating materials, such as diamond, offer defect centers whose
associated spins are well-isolated from their environment giving them long
coherence times; however, spin interactions are important for transport,
entanglement, and read-out. Here, we report direct measurement of pure spin
transport - free of any charge motion - within a nanoscale quasi 1D 'spin
wire', and find a spin diffusion length ~ 700 nm. We exploit the statistical
fluctuations of a small number of spins ($\sqrt{N}$ < 100 net spins) which are
in thermal equilibrium and have no imposed polarization gradient. The spin
transport proceeds by means of magnetic dipole interactions that induce
flip-flop transitions, a mechanism that can enable highly efficient, even
reversible, pure spin currents. To further study the dynamics within the spin
wire, we implement a magnetic resonance protocol that improves spatial
resolution and provides nanoscale spectroscopic information which confirms the
observed spin transport. This spectroscopic tool opens a potential route for
spatially encoding spin information in long-lived nuclear spin states. Our
measurements probe intrinsic spin dynamics at the nanometre scale, providing
detailed insight needed for practical devices which seek to control spin.


title:
Distributed Estimation and Control of Algebraic Connectivity over Random
  Graphs

abstract:
  In this paper we propose a distributed algorithm for the estimation and
control of the connectivity of ad-hoc networks in the presence of a random
topology. First, given a generic random graph, we introduce a novel stochastic
power iteration method that allows each node to estimate and track the
algebraic connectivity of the underlying expected graph. Using results from
stochastic approximation theory, we prove that the proposed method converges
almost surely (a.s.) to the desired value of connectivity even in the presence
of imperfect communication scenarios. The estimation strategy is then used as a
basic tool to adapt the power transmitted by each node of a wireless network,
in order to maximize the network connectivity in the presence of realistic
Medium Access Control (MAC) protocols or simply to drive the connectivity
toward a desired target value. Numerical results corroborate our theoretical
findings, thus illustrating the main features of the algorithm and its
robustness to fluctuations of the network graph due to the presence of random
link failures.


title: On topological and geometric $(19_4)$ configurations

abstract:
  An $(n_k)$ configuration is a set of $n$ points and $n$ lines such that each
point lies on $k$ lines while each line contains $k$ points. The configuration
is geometric, topological, or combinatorial depending on whether lines are
considered to be straight lines, pseudolines, or just combinatorial lines. The
existence and enumeration of $(n_k)$ configurations for a given $k$ has been
subject to active research. A current front of research concerns geometric
$(n_4)$ configurations: it is now known that geometric $(n_4)$ configurations
exist for all $n \ge 18$, apart from sporadic exceptional cases. In this paper,
we settle by computational techniques the first open case of $(19_4)$
configurations: we obtain all topological $(19_4)$ configurations among which
none are geometrically realizable.


title:
Spectral multiplexing for scalable quantum photonics using an atomic
  frequency comb quantum memory and feed-forward control

abstract:
  Future multi-photon applications of quantum optics and quantum information
science require quantum memories that simultaneously store many photon states,
each encoded into a different optical mode, and enable one to select the
mapping between any input and a specific retrieved mode during storage. Here we
show, with the example of a quantum repeater, how to employ
spectrally-multiplexed states and memories with fixed storage times that allow
such mapping between spectral modes. Furthermore, using a Ti:Tm:LiNbO3
waveguide cooled to 3 Kelvin, a phase modulator, and a spectral filter, we
demonstrate storage followed by the required feed-forward-controlled frequency
manipulation with time-bin qubits encoded into up to 26 multiplexed spectral
modes and 97% fidelity.


title: Correlation Function of Circular Wilson Loops at Strong Coupling

abstract:
  We study the correlation function of two circular Wilson loops at strong
coupling in N=4 super Yang-Mills theory. Using the AdS/CFT correspondence, the
problem maps to finding the minimal surface between two circles defined on the
boundary of AdS, and the fluctuations around the classical solution in AdS_5 x
S^5. At the classical level, we derive the string solution in H_3 x S^1
explicitly, and focus on properties such as stability and phase transition.
Furthermore, a computation of the associated algebraic curve is given. At the
quantum level, the one-loop partition function is constructed by introducing
quadratic bosonic and fermionic fluctuations around the classical solution,
embedded in AdS_5 x S^5. We find an analytic, formal expression for the
partition function in terms of an infinite product by employing the
Gel'fand-Yaglom method and supersymmetric regularization. We regulate the
expression and evaluate the partition function numerically.


title:
Analytical study of level crossings in the Stark-Zeeman spectrum of
  ground state OH

abstract:
  The ground electronic, vibrational and rotational state of the OH molecule is
currently of interest as it can be manipulated by electric and magnetic fields
for experimental studies in ultracold chemistry and quantum degeneracy. Based
on our recent exact solution of the corresponding effective Stark-Zeeman
Hamiltonian, we present an analytical study of the crossings and avoided
crossings in the spectrum. These features are relevant to non-adiabatic
transitions, conical intersections and Berry phases. Specifically, for an
avoided crossing employed in the evaporative cooling of OH, we compare our
exact results to those derived earlier from perturbation theory.


title: Cold Bose Atoms Around the Crossing of Quantum Waveguides

abstract:
  We show that massive low energy particles traversing a branching zone or a
crossing of quantum waveguides may experience a non standard trapping force
that cannot be derived from a potential. For interacting cold Bose atoms we
report on the formation of a localised Hartree ground state for three prototype
waveguide geometries with broken translational symmetry: a cranked L-shaped
waveguide L, a T-shaped waveguide T, and the crossing C of two quantum
waveguides. The phenomenon is kinetic energy driven and cannot be described
within the Thomas-Fermi approximation. Depending on the ratio of joining
lateral tube diameters of the respective waveguides C,L,T delocalisation
commences when the particle number N approaches a critical value. For the case
of a binary mixture of two different Bose atom species A and B we observe non
standard trapping of both atom species for subcritical particle numbers. A
sudden demixing quantum transition takes place as the total particle number
N=N_{A}+N_{B} is increased at fixed mixing ratio N_{A}/N_{B}. Depending on the
mass ratio m_{A}/m_{B} the heavier atom species delocalises first for a wide
range of interaction parameters. The numerical calculations are based on a
splitting scheme involving an analytic approximation to the short time
asymptotics of the imaginary time quantum propagator of a single particle
obeying to Dirichlet boundary conditions at the walls inside the respective
waveguides.

categories: cond-mat.quant-gas cond-mat.other math-ph math.MP quant-ph


title:
On the location of the gamma-ray emission region for 21 flat spectrum
  radio quasars with quasi-simultaneous observations

abstract:
  We try to infer the location of the GeV emission region for 21 flat spectrum
radio quasars (FSRQs) with quasi-simultaneous spectral energy distributions
(SEDs), in which the SEDs of 21 FSRQs are reproduced by the one-zone leptonic
model including the synchrotron-self Compton (SSC) and external Compton (EC)
processes. We suggest that the X-ray emission could be produced by the SSC
process and the GeV emission could come from the EC process. The EC emission
could originate from the inverse Compton (IC) scattering of photons from the
broad line region (BLR) and accretion disk or dust torus by the same electron
population, which mainly depend on the location of the $\gamma$-ray emission
region. We propose a method to constrain the location of the GeV emission
region based on the spectral shapes. When the GeV emission is located within
the BLR, the IC scattering could occur at the Klein-Nishina regime and produce
a broken/steep spectrum in the GeV energy band. When the GeV emission is
produced outside the BLR, the IC scattering could take place at the Thomson
regime and the GeV spectrum would have the same spectral index as the
optical-infrared spectrum. We infer that the location of the GeV emission
region is inside the BLR for 5 FSRQs and beyond the BLR for 16 FSRQs. Our
results show that the ratio of the magnetic field and electron energy density
is close to equipartition condition for 21 FSRQs.


title:
A UV complete model for radiative seesaw and electroweak baryogenesis
  based on the SUSY gauge theory

abstract:
  In a class of supersymmetric gauge theories with asymptotic freedom, the low
energy effective theory below the confinement scale is described by the
composite superfields of the fundamental representation fields. Based on the
supersymmetric gauge theory with N_c=2 and N_f=3 with an additional unbroken
Z_2 symmetry, we propose a new model where neutrino masses, dark matter, and
baryon asymmetry of the Universe can be simultaneously explained by physics
below the confinement scale. This is an example for the ultraviolet complete
supersymmetric extension of so-called radiative seesaw scenarios with
first-order phase transition required for successful electroweak baryogenesis.
We show that there are benchmark points where all the neutrino data, the lepton
flavor violation data, and the LHC data are satisfied. We also briefly discuss
Higgs phenomenology in this model.


title: Feedback-induced nonlinearity and superconducting on-chip quantum optics

abstract:
  Quantum coherent feedback has been proven to be an efficient way to tune the
dynamics of quantum optical systems and, recently, those of solid-state quantum
circuits. Here, inspired by the recent progress of quantum feedback
experiments, especially those in mesoscopic circuits, we prove that
superconducting circuit QED systems, shunted with a coherent feedback loop, can
change the dynamics of a superconducting transmission line resonator, i.e., a
linear quantum cavity, and lead to strong on-chip nonlinear optical phenomena.
We find that bistability can occur under the semiclassical approximation, and
photon anti-bunching can be shown in the quantum regime. Our study presents new
perspectives for engineering nonlinear quantum dynamics on a chip.


title: Pairs of $k$-step reachability and $m$-step observability matrices

abstract:
  Let $V$ and $W$ be matrices of size $ n \times pk$ and $q m \times n $,
respectively. A necessary and sufficient condition is given for the existence
of a triple $(A,B,C)$ such that $V$ a $k$-step reachability matrix of $(A,B)$
and $W$ an $m$-step observability matrix of $(A,C)$.


title: O-notation in algorithm analysis

abstract:
  We provide an extensive list of desirable properties for an O-notation --- as
used in algorithm analysis --- and reduce them to 8 primitive properties. We
prove that the primitive properties are equivalent to the definition of the
O-notation as linear dominance. We abstract the existing definitions of the
O-notation under local linear dominance, and show that it has a
characterization by limits over filters for positive functions. We define the
O-mappings as a general tool for manipulating the O-notation, and show that
Master theorems hold under linear dominance.


title:
"Science in Tales": Analysis of the images of scientist in young
  people's fictional literature

abstract:
  In the research field on the "images of scientists" that appear in fictional
literature, we focus on a set of tales produced by students of secondary
school. Our aim is to connect some traits of the stereotypical scientist that
appear in those texts with the traits underlying other cultural productions,
since those productions may constitute the probable source of the stereotype.
Many common representations of the scientist emerge from an image of science
that is inadequate from the point of view of science teaching. It correlates to
a lack of interest towards science courses. This lack of interest would
contribute to stagnation in the number of students pursuing science and
technology careers in Ibero-America in general and especially in Argentina.


title: Momentum broadening of partons on the light cone from the lattice

abstract:
  The jet quenching parameter describes the momentum broadening of a
high-energy parton moving through the quark-gluon plasma. Following an approach
originally proposed by Caron-Huot, we discuss how one can extract information
on the collision kernel associated with the parton momentum broadening, from
the analysis of certain gauge-invariant operators in dimensionally reduced
effective theories, and present numerical results from a lattice study.


title: Newton-like equations for a radiating particle

abstract:
  Second order Newton equations of motion for a radiating particle are
presented. It is argued that the trajectories obeying them also satisfy the
Abraham-Lorentz-Dirac (ALD) equations for general 3D motions in the
non-relativistic and relativistic limits. The case of forces only depending of
the proper time is here considered. For these properties to hold, it is
sufficient that the external force to be infinitely smooth and that a series
formed with its time derivatives converges. This series define in a special
local way the effective forces entering the Newton equations. When the external
force vanishes in an open vicinity of a given time, the effective one also
becomes null. Thus, the proper solutions of the effective equations can not
show runaway or pre-acceleration effects. The Newton equations are numerically
solved for a pulsed force given by an analytic function along the proper time
axis. The simultaneous satisfaction of the ALD equations is numerically
checked. Further, a set of modified ALD equations for almost everywhere
infinitely smooth forces, but including step like discontinuities in some
points is also presented for the case of collinear motions. The form of the
equations supports the statement argued in a previous work, about that the
causal Lienard-Wiechert field solution surrounding a radiating particle,
implies that the effective force on the particle should instantaneously vanish
when the external force is retired. The modified ALD equations proposed in the
previous work are here derived in a generalized way including the same effect
also when a the force is instantly connected.


title:
Modeling Based on Elman Wavelet Neural Network for Class-D Power
  Amplifiers

abstract:
  In Class-D Power Amplifiers (CDPAs), the power supply noise can intermodulate
with the input signal, manifesting into power-supply induced intermodulation
distortion (PS-IMD) and due to the memory effects of the system, there exist
asymmetries in the PS-IMDs. In this paper, a new behavioral modeling based on
the Elman Wavelet Neural Network (EWNN) is proposed to study the nonlinear
distortion of the CDPAs. In EWNN model, the Morlet wavelet functions are
employed as the activation function and there is a normalized operation in the
hidden layer, the modification of the scale factor and translation factor in
the wavelet functions are ignored to avoid the fluctuations of the error
curves. When there are 30 neurons in the hidden layer, to achieve the same
square sum error (SSE) $\epsilon_{min}=10^{-3}$, EWNN needs 31 iteration steps,
while the basic Elman neural network (BENN) model needs 86 steps. The
Volterra-Laguerre model has 605 parameters to be estimated but still can't
achieve the same magnitude accuracy of EWNN. Simulation results show that the
proposed approach of EWNN model has fewer parameters and higher accuracy than
the Volterra-Laguerre model and its convergence rate is much faster than the
BENN model.


title:
Cosmographic analysis of the equation of state of the universe through
  Pad\'e approximations

abstract:
  Cosmography is used in cosmological data processing in order to constrain the
kinematics of the universe in a model-independent way, providing an objective
means to evaluate the agreement of a model with observations. In this paper, we
extend the conventional methodology of cosmography employing Taylor expansions
of observables by an alternative approach using Pad\'e approximations. Due to
the superior convergence properties of Pad\'e expansions, it is possible to
improve the fitting analysis to obtain numerical values for the parameters of
the cosmographic series. From the results, we can derive the equation of state
parameter of the universe and its first derivative and thus acquire information
about the thermodynamic state of the universe. We carry out statistical
analyses using observations of the distance modulus of type 1a supernovae,
provided by the union 2.1 compilation of the supernova cosmology project,
employing a Markov chain Monte Carlo approach with an implemented Metropolis
algorithm. We compare the results of the original Taylor approach to the newly
introduced Pad\'e formalism. The analyses show that experimental data constrain
the observable universe well, finding an accelerating universe and a positive
jerk parameter. We demonstrate that the Pad\'e convergence radii are greater
than standard Taylor convergence radii, and infer a lower limit on the
acceleration of the universe solely by requiring the positivity of the Pad\'e
expansion. We obtain fairly good agreement with the Planck results, confirming
the $\Lambda$CDM model at small redshifts, although we cannot exclude a dark
energy density varying in time with negligible speed of sound.


title:
Forward Neutral Pion Cross Section and Spin Asymmetry Measurements at
  STAR

abstract:
  The STAR endcap electromagnetic calorimeter (EEMC) was designed to allow
measurement of cross sections and spin observables in the forward direction, $1
< \eta < 2$ and with the full azimuth. Using the EEMC to measure double
longitudinal spin asymmetries in photonic channels---such as inclusive neutral
pions, prompt photon, and prompt photon + jet---allows access to $\Delta G$
within a low Bjorken-$x$ region ($0.01 < x < 0.33$ at $\sqrt{s}=200$) where
$\Delta G$ is poorly constrained. Additionally, transverse spin asymmetries,
shown to be zero at $\eta$ near zero and as large as 10\% at $\eta$ near 4,
occupy a previously unmeasured region in the 3D pseudorapidity, transverse
momentum, and $x$-Feynman phase space when measured with the EEMC. The neutral
pion cross section measurement verifies that the signal of interest can be
properly reconstructed and isolated from the background. Pion reconstruction
techniques in the STAR EEMC will be discussed and preliminary cross-section and
transverse single spin asymmetry measurements presented.


title: Metropolis-Hastings within Partially Collapsed Gibbs Samplers

abstract:
  The Partially Collapsed Gibbs (PCG) sampler offers a new strategy for
improving the convergence of a Gibbs sampler. PCG achieves faster convergence
by reducing the conditioning in some of the draws of its parent Gibbs sampler.
Although this can significantly improve convergence, care must be taken to
ensure that the stationary distribution is preserved. The conditional
distributions sampled in a PCG sampler may be incompatible and permuting their
order may upset the stationary distribution of the chain. Extra care must be
taken when Metropolis-Hastings (MH) updates are used in some or all of the
updates. Reducing the conditioning in an MH within Gibbs sampler can change the
stationary distribution, even when the PCG sampler would work perfectly if MH
were not used. In fact, a number of samplers of this sort that have been
advocated in the literature do not actually have the target stationary
distributions. In this article, we illustrate the challenges that may arise
when using MH within a PCG sampler and develop a general strategy for using
such updates while maintaining the desired stationary distribution. Theoretical
arguments provide guidance when choosing between different MH within PCG
sampling schemes. Finally we illustrate the MH within PCG sampler and its
computational advantage using several examples from our applied work.


title:
Packing hard spheres with short-range attraction in infinite dimension:
  Phase structure and algorithmic implications

abstract:
  We study, via the replica method of disordered systems, the packing problem
of hard-spheres with a square-well attractive potential when the space
dimensionality, d, becomes infinitely large. The phase diagram of the system
exhibits reentrancy of the liquid-glass transition line, two distinct glass
states and a glass-to-glass transition, much similar to what has been
previously obtained by Mode-Coupling Theory, numerical simulations and
experiments. The presence of the phase reentrance implies that for a suitable
choice of the intensity and attraction range, high-density sphere packings more
compact than the one corresponding to pure hard-spheres can be constructed in
polynomial time in the number of particles (at fixed, large d) for packing
fractions smaller than 6.5 d 2^{-d}. Although our derivation is not a formal
mathematical proof, we believe it meets the standards of rigor of theoretical
physics, and at this level of rigor it provides a small improvement of the
lower bound on the sphere packing problem.


title: Unimodular homotopy algebras and Chern-Simons theory

abstract:
  Quantum Chern-Simons invariants of differentiable manifolds are analyzed from
the point of view of homological algebra. Given a manifold M and a Lie (or,
more generally, an L-infinity) algebra g, the vector space H^*(M) \otimes g has
the structure of an L-infinity algebra whose homotopy type is a homotopy
invariant of M. We formulate necessary and sufficient conditions for this
L-infinity algebra to have a quantum lift. We also obtain structural results on
unimodular L-infinity algebras and introduce a doubling construction which
links unimodular and cyclic L-infinity algebras.


title:
Projected and Hidden Markov Models for calculating kinetics and
  metastable states of complex molecules

abstract:
  Markov state models (MSMs) have been successful in computing metastable
states, slow relaxation timescales and associated structural changes, and
stationary or kinetic experimental observables of complex molecules from large
amounts of molecular dynamics simulation data. However, MSMs approximate the
true dynamics by assuming a Markov chain on a clusters discretization of the
state space. This approximation is difficult to make for high-dimensional
biomolecular systems, and the quality and reproducibility of MSMs has therefore
been limited. Here, we discard the assumption that dynamics are Markovian on
the discrete clusters. Instead, we only assume that the full phase- space
molecular dynamics is Markovian, and a projection of this full dynamics is
observed on the discrete states, leading to the concept of Projected Markov
Models (PMMs). Robust estimation methods for PMMs are not yet available, but we
derive a practically feasible approximation via Hidden Markov Models (HMMs). It
is shown how various molecular observables of interest that are often computed
from MSMs can be computed from HMMs / PMMs. The new framework is applicable to
both, simulation and single-molecule experimental data. We demonstrate its
versatility by applications to educative model systems, an 1 ms Anton MD
simulation of the BPTI protein, and an optical tweezer force probe trajectory
of an RNA hairpin.


title:
Coherent Structure in Solar Wind C$^{6+}$/C$^{4+}$ Ionic Composition
  Data During the Quiet-Sun Conditions of 2008

abstract:
  This analysis offers evidence of characteristic scale sizes in solar wind
charge state data measured in-situ for thirteen quiet-sun Carrington rotations
in 2008. Using a previously established novel methodology, we analyze the
wavelet power spectrum of the charge state ratio C$^{6+}$/C$^{4+}$ measured
in-situ by ACE/SWICS for 2-hour and 12-minute cadence. We construct a
statistical significance level in the wavelet power spectrum to quantify the
interference effects arising from filling missing data in the time series
(Edmondson et al. 2013), allowing extraction of significant power from the
measured data to a resolution of 24 mins. We analyze each wavelet power spectra
for transient coherency, and global periodicities resulting from the
superposition of repeating coherent structures. From the significant wavelet
power spectra, we find evidence for a general upper-limit on individual
transient coherency of $\sim$10 days. We find evidence for a set of global
periodicities between 4-5 hours and 35-45 days. We find evidence for the
distribution of individual transient coherency scales consisting of two
distinct populations. Below the $\sim$2 day time scale the distribution is
reasonably approximated by an inverse power law, whereas for scales $\gtrsim$2
days, the distribution levels off showing discrete peaks at common coherency
scales. In addition, by organizing the transient coherency scale distributions
by wind type, we find these larger, common coherency scales are more prevalent
and well-defined in coronal hole wind. Finally, we discuss the implications of
our results for current theories of solar wind generation and describe future
work for determining the relationship between the coherent structures in our
ionic composition data and the structure of the coronal magnetic field.


title:
One-Dimensional Dispersive Magnon Excitation in the Frustrated Spin-2
  Chain System Ca3Co2O6

abstract:
  Using inelastic neutron scattering, we have observed a quasi-one-dimensional
dispersive magnetic excitation in the frustrated triangular-lattice spin-2
chain oxide Ca3Co2O6. At the lowest temperature (T = 1.5 K), this magnon is
characterized by a large zone-center spin gap of ~27 meV, which we attribute to
the large single-ion anisotropy, and disperses along the chain direction with a
bandwidth of ~3.5 meV. In the directions orthogonal to the chains, no
measurable dispersion was found. With increasing temperature, the magnon
dispersion shifts towards lower energies, yet persists up to at least 150 K,
indicating that the ferromagnetic intrachain correlations survive up to 6 times
higher temperatures than the long-range interchain antiferromagnetic order. The
magnon dispersion can be well described within the predictions of linear
spin-wave theory for a system of weakly coupled ferromagnetic chains with large
single-ion anisotropy, enabling the direct quantitative determination of the
magnetic exchange and anisotropy parameters.


title: Partitioning into Expanders

abstract:
  Let G=(V,E) be an undirected graph, lambda_k be the k-th smallest eigenvalue
of the normalized laplacian matrix of G. There is a basic fact in algebraic
graph theory that lambda_k > 0 if and only if G has at most k-1 connected
components. We prove a robust version of this fact. If lambda_k>0, then for
some 1\leq \ell\leq k-1, V can be {\em partitioned} into l sets P_1,\ldots,P_l
such that each P_i is a low-conductance set in G and induces a high conductance
induced subgraph. In particular, \phi(P_i)=O(l^3\sqrt{\lambda_l}) and
\phi(G[P_i]) >= \lambda_k/k^2).
  We make our results algorithmic by designing a simple polynomial time
spectral algorithm to find such partitioning of G with a quadratic loss in the
inside conductance of P_i's. Unlike the recent results on higher order
Cheeger's inequality [LOT12,LRTV12], our algorithmic results do not use higher
order eigenfunctions of G. If there is a sufficiently large gap between
lambda_k and lambda_{k+1}, more precisely, if \lambda_{k+1} >= \poly(k)
lambda_{k}^{1/4} then our algorithm finds a k partitioning of V into sets
P_1,...,P_k such that the induced subgraph G[P_i] has a significantly larger
conductance than the conductance of P_i in G. Such a partitioning may represent
the best k clustering of G. Our algorithm is a simple local search that only
uses the Spectral Partitioning algorithm as a subroutine. We expect to see
further applications of this simple algorithm in clustering applications.


title: Nambu-Goldstone modes in segregated Bose-Einstein condensates

abstract:
  Nambu-Goldstone modes in immiscible two-component Bose-Einstein condensates
are studied theoretically. In a uniform system, a flat domain wall is
stabilized and then the translational invariance normal to the wall is
spontaneously broken in addition to the breaking of two U(1) symmetries in the
presence of two complex order parameters. We clarify properties of the
low-energy excitations and identify that there exist two Nambu-Goldstone modes:
in-phase phonon with a linear dispersion and ripplon with a fractional
dispersion. The signature of the characteristic dispersion can be verified in
segregated condensates in a harmonic potential.


title: Creation of matter wave Bessel beams

abstract:
  Bessel beams are plane waves with amplitude profiles described by Bessel
functions. They are important because of their property of limited diffraction
and their capacity to carry orbital angular momentum. Here we report the
creation of a Bessel beam of de Broglie matter waves. The Bessel beam is
produced by the free evolution of a thin toroidal atomic Bose-Einstein
condensate (BEC) which has been set into rotational motion. By attempting to
stir it at different rotation rates, we show that the toroidal BEC can only be
made to rotate at discrete, equally-spaced frequencies, demonstrating that
circulation is quantized in atomic BECs. The method used here to generate
matter wave Bessel beams with a Painted Potential can be viewed as a form of
wavefunction engineering which might be extended to implement arbitrary cold
atom matter wave holography.


title:
Giant Quasiparticle Bandgap Modulation in Graphene Nanoribbons Supported
  on Weakly Interacting Surfaces

abstract:
  In general, there are two major factors affecting bandgaps in nanostructures:
(i) the enhanced electron-electron interactions due to confinement and (ii) the
modified self-energy of electrons due to the dielectric screening. While recent
theoretical studies on graphene nanoribbons (GNRs) report on the first effect,
the effect of dielectric screening from the surrounding materials such as
substrates has not been thoroughly investigated. Using large-scale electronic
structure calculations based on the GW approach, we show that when GNRs are
deposited on substrates, bandgaps get strongly suppressed (by as much as 1 eV)
even though the GNR-substrate interaction is weak.


title:
Thermomechanics of hydrogen storage in metallic hydrides: modeling and
  analysis

abstract:
  A thermodynamically consistent mathematical model for hydrogen adsorption in
metal hydrides is proposed. Beside hydrogen diffusion, the model accounts for
phase transformation accompanied by hysteresis, swelling, temperature and heat
transfer, strain, and stress. We prove existence of solutions of the ensuing
system of partial differential equations by a carefully-designed, semi-implicit
approximation scheme. A generalization for a drift-diffusion of multi-component
ionized "gas" is outlined, too.

categories: math-ph cond-mat.mtrl-sci math.AP math.MP


title:
Quantum hypothesis testing and the operational interpretation of the
  quantum Renyi relative entropies

abstract:
  We show that the new quantum extension of Renyi's \alpha-relative entropies,
introduced recently by Muller-Lennert, Dupuis, Szehr, Fehr and Tomamichel, J.
Math. Phys. 54, 122203, (2013), and Wilde, Winter, Yang, Commun. Math. Phys.
331, (2014), have an operational interpretation in the strong converse problem
of quantum hypothesis testing. Together with related results for the direct
part of quantum hypothesis testing, known as the quantum Hoeffding bound, our
result suggests that the operationally relevant definition of the quantum Renyi
relative entropies depends on the parameter \alpha: for \alpha<1, the right
choice seems to be the traditional definition, whereas for \alpha>1 the right
choice is the newly introduced version.
  As a sideresult, we show that the new Renyi \alpha-relative entropies are
asymptotically attainable by measurements for \alpha>1, and give a new simple
proof for their monotonicity under completely positive trace-preserving maps.


title:
Evidence for high-energy resummation effects in Mueller-Navelet jets at
  the LHC

abstract:
  The study of the production of two forward jets with a large interval of
rapidity at hadron colliders was proposed by Mueller and Navelet as a possible
test of the high energy dynamics of QCD. We analyze this process within a
complete next-to-leading logarithm framework, supplemented by the use of the
Brodsky-Lepage-Mackenzie procedure extended to the perturbative Regge dynamics,
to find the optimal renormalization scale. This leads to a very good
description of the recent CMS data at LHC for the azimuthal correlations of the
jets.


title:
Search for new phenomena in photon+jet events collected in
  proton--proton collisions at sqrt(s) = 8 TeV with the ATLAS detector

abstract:
  This Letter describes a model-independent search for the production of new
resonances in photon + jet events using 20 inverse fb of proton--proton LHC
data recorded with the ATLAS detector at a centre-of-mass energy of sqrt(s) = 8
TeV. The photon + jet mass distribution is compared to a background model fit
from data; no significant deviation from the background-only hypothesis is
found. Limits are set at 95% credibility level on generic Gaussian-shaped
signals and two benchmark phenomena beyond the Standard Model: non-thermal
quantum black holes and excited quarks. Non-thermal quantum black holes are
excluded below masses of 4.6 TeV and excited quarks are excluded below masses
of 3.5 TeV.


title: On Brendle's estimate for the inscribed radius under mean curvature flow

abstract:
  In a recent paper, Brendle proved that the inscribed radius of closed
embedded mean convex hypersurfaces moving by mean curvature flow is at least
1/((1+\delta)H) at all points with H > C(\delta,M_0). In this note, we give a
shorter proof of Brendle's estimate, and of a more general result for
alpha-Andrews flows, based on our recent estimates from Haslhofer-Kleiner.


title: Role of Te in the low dimensional multiferroic material FeTe2O5Br

abstract:
  Using first principles density functional calculations, we study the
electronic structure of the low-dimensional multiferroic compound FeTe2O5Br to
investigate the origin of the magnetoelectric (ME) effect and the role of Te
ions in this system. We find that without magnetism even in the presence of
Te-5s lone pairs, the system remains centrosymmetric due to the antipolar
orientation of the lone pairs. Our study shows that the exchange striction
within the Fe tetramers as well as between them is responsible for the ME
effect in FeTe2O5Br. We also find that the Te^4+ ions play an important role in
the inter-tetramer exchange striction as well as contribute to the electric
polarization in FeTe2O5Br, once the polarization is triggered by the magnetic
ordering.


title:
Efficient Orthogonal Tensor Decomposition, with an Application to Latent
  Variable Model Learning

abstract:
  Decomposing tensors into orthogonal factors is a well-known task in
statistics, machine learning, and signal processing. We study orthogonal outer
product decompositions where the factors in the summands in the decomposition
are required to be orthogonal across summands, by relating this orthogonal
decomposition to the singular value decompositions of the flattenings. We show
that it is a non-trivial assumption for a tensor to have such an orthogonal
decomposition, and we show that it is unique (up to natural symmetries) in case
it exists, in which case we also demonstrate how it can be efficiently and
reliably obtained by a sequence of singular value decompositions. We
demonstrate how the factoring algorithm can be applied for parameter
identification in latent variable and mixture models.


title:
How cold can you get in space? Quantum Physics at cryogenic temperatures
  in space

abstract:
  Although it is often believed that the coldness of space is ideally suited
for performing measurements at cryogenic temperatures, this must be regarded
with caution for two reasons: Firstly, the sensitive instrument must be
completely shielded from the strong solar radiation and therefore, e.g. either
be placed inside a satellite or externally on the satellite's shaded side.
Secondly, any platform hosting such an experiment in space generally provides
an environment close to room temperature for the accommodated equipment. To
obtain cryogenic temperatures without active cooling, one must isolate the
instrument from radiative and conductive heat exchange with the platform as
well as possible. We investigate the limits of this passive cooling method in
the context of a recently proposed experiment to observe the decoherence of
quantum superpositions of massive objects. The analyses and conclusions are
applicable to a host of similar experimental designs requiring a cryogenic
environment in space.

categories: quant-ph astro-ph.IM gr-qc physics.ins-det physics.space-ph


title: Transformations between Composite and Visitor implementations in Java

abstract:
  Basic automated refactoring operations can be chained to perform complex
structure transformations. This is useful for recovering the initial
architecture of a source code which has been degenerated with successive
evolutions during its maintenance lifetime. This is also useful for changing
the structure of a program so that a maintenance task at hand becomes modular
when it would be initially crosscutting. We focus on programs structured
according to Composite and Visitor design patterns, which have dual properties
with respect to modularity. We consider a refactoring-based round-trip
transformation between these two structures and we study how that
transformation is impacted by four variations in the implementation of these
patterns. We validate that study by computing the smallest preconditions for
the resulting transformations. We also automate the transformation and apply it
to JHotDraw, where the studied variations occur.


title: non-BPS walls of marginal stability

abstract:
  We explore the properties of non-BPS multi-centre extremal black holes in
ungauged N=2 supergravity coupled to n_v vector multiplets, as described by
solutions to the composite non-BPS linear system. After setting up an explicit
description that allows for arbitrary non-BPS charges to be realised at each
centre, we study the structure of the resulting solutions. Using these results,
we prove that the binding energy of the composite is always positive and we
show explicitly the existence of walls of marginal stability for generic
choices of charges. The two-centre solutions only exist on a hypersurface of
dimension n_v+1 in moduli space, with an n_v-dimensional boundary, where the
distance between the centres diverges and the binding energy vanishes.