title:
Optimal Transmit Power Allocation for MIMO Two-Way Cognitive Relay
  Networks with Multiple Relays

abstract:
  In this letter, we consider a multiple-input multiple-output two-way
cognitive radio system under a spectrum sharing scenario, where primary and
secondary users operate on the same frequency band. The secondary terminals
aims to exchange different messages with each other using multiple relays where
each relay employs an amplify-and-forward strategy. The main objective of our
work is to maximize the secondary sum rate allowed to share the spectrum with
the primary users by respecting a primary user tolerated interference
threshold. In this context, we derive a closed-form expression of the optimal
power allocated to each antenna of the terminals. We then discuss the impact of
some system parameters on the performance in the numerical result section.


title: Solar neutrino physics: Sensitivity to light dark matter particles

abstract:
  Neutrinos are produced in several neutrino nuclear reactions of the
proton-proton chain and carbon-nitrogen-oxygen cycle that take place at
different radius of the Sun's core. Hence, measurements of solar neutrino
fluxes provide a precise determination of the local temperature. The
accumulation of non-annihilating light dark matter particles (with masses
between 5 GeV and 16 GeV in the Sun produces a change in the local solar
structure, namely, a decrease in the central temperature of a few percent. This
variation depends on the properties of the dark matter particles, such as the
mass of the particle and its spin-independent scattering cross-section on
baryon-nuclei, specifically, the scattering with helium, oxygen, and nitrogen
among other heavy elements. This temperature effect can be measured in almost
all solar neutrino fluxes. In particular, by comparing the neutrino fluxes
generated by stellar models with current observations, namely 8B neutrino
fluxes, we find that non-annihilating dark matter particles with a mass smaller
than 10 GeV and a spin-independent scattering cross-section with heavy
baryon-nuclei larger than 3 x 10^{-37} cm^-2 produce a variation in the 8B
neutrino fluxes that would be in conflict with current measurements.


title: Structure of Kernels and Cokernels of Toeplitz plus Hankel Operators

abstract:
  Toeplitz plus Hankel operators $T(a)+H(b)$, $a,b\in L^\infty$ acting on the
classical Hardy spaces $H^p, 1<p<\infty$, are studied. If the generating
functions $a$ and $b$ satisfy the so-called matching condition $a(t)
a(1/t)=b(t) b(1/t)$, an effective description of the structure of the kernel
and cokernel of the corresponding operator is given. The results depend on the
behaviour of two auxiliary scalar Toeplitz operators, and if the generating
functions $a$ and $b$ are piecewise continuous, more detailed results are
obtained.


title:
Condensation of Photons coupled to a Dicke Field in an Optical
  Microcavity

abstract:
  Motivated by recent experiments reporting Bose-Einstein condensation (BEC) of
light coupled to incoherent dye molecules in a microcavity, we show that due to
a dimensionality mismatch between the 2D cavity-photons and the 3D arrangement
of molecules, the relevant molecular degrees of freedom are collective Dicke
states rather than individual excitations. For sufficiently high dye
concentration the coupling of the Dicke states with light will dominate over
local decoherence. This system also shows Mott criticality despite the absence
of an underlying lattice in the limit when all dye molecules become excited.


title:
Towards spaces of harmonic functions with traces in square Campanato
  space and its scaling invariant

abstract:
  For $n\ge 1$ and $\alpha\in (-1,1)$, let $H^{\alpha,2}$ be the space of
harmonic functions $u$ on the upper half space $\mathbb{R}^{n+1}_+$ satisfying
$$\displaystyle\sup_{(x_0,r)\in \mathbb
R^{n+1}_+}r^{-(2\alpha+n)}\int_{B(x_0,r)}\int_0^r|\nabla_{x,t}
u(x,t)|^2t\,dt\,dx<\infty,$$ and $\mathcal{L}_{2,n+2\alpha}$ be the Campanato
space on $\mathbb R^n$. We show that $H^{\alpha,2}$ coincide with
$e^{-t\sqrt{-\Delta}}\mathcal{L}_{2,n+2\alpha}$ for all $\alpha\in (-1,1)$,
where the case $\alpha\in [0,1)$ was originally discovered by Fabes, Johnson
and Neri [Indiana Univ. Math. J. 25 (1976), 159-170] and yet the case
$\alpha\in (-1,0)$ was left open. Moreover, for the scaling invariant version
of $H^{\alpha,2}$, $\mathcal{H}^{\alpha,2}$, which comprises all harmonic
functions $u$ on $\mathbb R^{n+1}_+$ satisfying $$\sup_{(x_0,r)\in\mathbb
R^{n+1}_+}r^{-(2\alpha+n)}\int_{B(x_0,r)} \int_0^r|\nabla_{x,t}
u(x,t)|^2\,t^{1+2\alpha} \,dt\,dx<\infty,$$ we show that
$\mathcal{H}^{\alpha,2}=e^{-t\sqrt{-\Delta}}(-\Delta)^\frac{\alpha}{2}\mathcal{L}_{2,n+2\alpha}$,
where $(-\Delta)^{\frac{\alpha}{2}}\mathcal{L}_{2,n+2\alpha}$ is the collection
of all functions $f$ such that $(-\Delta)^{-\frac{\alpha}{2}}f$ are in
$\mathcal{L}_{2,n+2\alpha}$. Analogues for solutions to the heat equation are
also established. As an application, we show that the spaces
$\big((-\Delta)^{\frac{\alpha}{2}}\mathcal{L}_{2,n+2\alpha}\big)^{-1}$ unify
$Q_{\alpha}^{-1}$, ${\mathrm{BMO}}^{-1}$ and $\dot{B}^{-1,\infty}_\infty$
naturally.


title:
Multichannel scanning probe microscopy and spectroscopy of graphene
  moire structures

abstract:
  The graphene moire structures on metals, as they demonstrate both long
(moire) and short (atomic) scale ordered structures, are the ideal systems for
the application of scanning probe methods. Here we present the complex studies
of the graphene/Ir(111) system by means of 3D scanning tunnelling and atomic
force microscopy/spectroscopy as well as Kelvin-probe force microscopy. All
results clearly demonstrate a variation of the moire and atomic scale contrasts
as a function of the bias voltage as well as the distance between the scanning
probe and the sample, allowing to discriminate between topographic and
electronic contributions in the imaging of a graphene layer on metals. The
presented results are accompanied by the state-of-the-art density functional
theory calculations demonstrating the excellent agreement between theoretical
and experimental data.


title: Thermal duality and gravitational collapse in heterotic string theories

abstract:
  The thermal duality of E(8) x E(8) and SO(32) heterotic string theories may
underpin a mechanism that would convert the kinetic energy of infalling matter
during gravitational collapse to form a region of a hot string phase that would
expel gravitational gradients. This phase would be the continuation of a
Ginzburg-Landau like superconductor in the Euclidean regime. In this scenario,
there would be no event horizon or singularity produced in gravitational
collapse. Solutions are presented for excitations of the string vacuum that may
form during gravitational collapse and drive the transition to the hot phase.
The proposed mechanism is developed here for the case of approximately
spherical gravitational collapse in 4 uncompactified spacetime dimensions. A
way to reconcile the large entropy apparently produced in this process with
quantum mechanics is briefly discussed. In this scenario, astrophysical objects
such as stellar or galactic cores which have undergone extreme gravitational
collapse would currently be sites of an on-going conversion process to shells
of this high temperature phase. The relationship of this proposal to the
`firewall paradox' is noted.


title: A Structure result for bricks in Heisenberg groups

abstract:
  We show that for a sufficiently big \textit{brick} $B$ of the
$(2n+1)$-dimensional Heisenberg group $H_n$ over the finite field
$\mathbb{F}_p$, the product set $B\cdot B$ contains at least $|B|/p$ many
cosets of some non trivial subgroup of $H_n$.


title:
Conditional expanding bounds for two-variables functions over prime
  fields

abstract:
  In this paper we provide in $\bFp$ expanding lower bounds for two variables
functions $f(x,y)$ in connection with the product set or the sumset. The
sum-product problem has been hugely studied in the recent past. A typical
result in $\bFp^*$ is the existenceness of $\Delta(\alpha)>0$ such that if
$|A|\asymp p^{\alpha}$ then $$ \max(|A+A|,|A\cdot A|)\gg
|A|^{1+\Delta(\alpha)}, $$ Our aim is to obtain analogous results for related
pairs of two-variable functions $f(x,y)$ and $g(x,y)$: if $|A|\asymp|B|\asymp
p^{\alpha}$ then $$ \max(|f(A,B)|,|g(A,B)|)\gg |A|^{1+\Delta(\alpha)} $$ for
some $\Delta(\alpha)>0$.


title: A Light Sterile Neutrino from Friedberg-Lee Symmetry

abstract:
  Light sterile neutrinos of mass about an eV with mixing $\tilde U_{ls}$ of a
few percent to active neutrinos may solve some anomalies shown in experimental
data related to neutrino oscillation. How to have light sterile neutrinos is
one of the theoretical problems which have attracted a lot of attentions. In
this article we show that such an eV scale light sterile neutrino candidate can
be obtained in a seesaw model in which the right-handed neutrinos satisfy a
softly-broken Friedberg-Lee (FL) symmetry. In this model a right-handed
neutrino is guaranteed by the FL symmetry to be light comparing with other two
heavy right-handed neutrinos. It can be of eV scale when the FL symmetry is
softly broken and can play the role of eV scale sterile neutrino needed for
explaining the anomalies of experimental data. This model predicts that one of
the active neutrino is massless. We find that this model prefers inverted
hierarchy mass pattern of active neutrinos than normal hierarchy. An
interesting consequence of this model is that realizing relatively large
$|{\tilde U}_{es}|$ and relatively small $|{\tilde U}_{\mu s}|$ in this model
naturally leads to a relatively small $|{\tilde U}_{\tau s}|$. This interesting
prediction can be tested in future atmospheric or solar neutrino experiments.


title: Particle Production from Geometric Transition in Expanding Universe

abstract:
  The geometric transitions from the evolution in the complex plane of time
provide channels for particle production for a quantum field in expanding
universes. The production rate for one pair is obtained by squaring and summing
the scattering matrix between the in-vacuum and the transported one over all
possible independent closed paths of winding number 1.


title:
Optimized Bit Mappings for Spatially Coupled LDPC Codes over Parallel
  Binary Erasure Channels

abstract:
  In many practical communication systems, one binary encoder/decoder pair is
used to communicate over a set of parallel channels. Examples of this setup
include multi-carrier transmission, rate-compatible puncturing of turbo-like
codes, and bit-interleaved coded modulation (BICM). A bit mapper is commonly
employed to determine how the coded bits are allocated to the channels. In this
paper, we study spatially coupled low-density parity check codes over parallel
channels and optimize the bit mapper using BICM as the driving example. For
simplicity, the parallel bit channels that arise in BICM are replaced by
independent binary erasure channels (BECs). For two parallel BECs modeled
according to a 4-PAM constellation labeled by the binary reflected Gray code,
the optimization results show that the decoding threshold can be improved over
a uniform random bit mapper, or, alternatively, the spatial chain length of the
code can be reduced for a given gap to capacity. It is also shown that for
rate-loss free, circular (tail-biting) ensembles, a decoding wave effect can be
initiated using only an optimized bit mapper.


title: Parsing methods streamlined

abstract:
  This paper has the goals (1) of unifying top-down parsing with shift-reduce
parsing to yield a single simple and consistent framework, and (2) of producing
provably correct parsing methods, deterministic as well as tabular ones, for
extended context-free grammars (EBNF) represented as state-transition networks.
Departing from the traditional way of presenting as independent algorithms the
deterministic bottom-up LR(1), the top-down LL(1) and the general tabular
(Earley) parsers, we unify them in a coherent minimalist framework. We present
a simple general construction method for EBNF ELR(1) parsers, where the new
category of convergence conflicts is added to the classical shift-reduce and
reduce-reduce conflicts; we prove its correctness and show two implementations
by deterministic push-down machines and by vector-stack machines, the latter to
be also used for Earley parsers. Then the Beatty's theoretical characterization
of LL(1) grammars is adapted to derive the extended ELL(1 parsing method, first
by minimizing the ELR(1) parser and then by simplifying its state information.
Through using the same notations in the ELR(1) case, the extended Earley parser
is obtained. Since all the parsers operate on compatible representations, it is
feasible to combine them into mixed mode algorithms.


title:
Spin nutation effects in molecular nanomagnet$-$superconductor tunnel
  junctions

abstract:
  We study the spin nutation effects of the molecular nanomagnet on the
Josephson current through a superconductor$|$molecular
nanomagnet$|$superconductor tunnel junction. We explicitly demonstrate that due
to the spin nutation of the molecular nanomagnet two oscillatory terms emerge
in the $ac$ Josephson current in addition to the conventional $ac$ Josephson
current. Some resonances occur in the junction due to the interactions of the
transported quasiparticles with the bias voltage and molecular nanomagnet spin
dynamics. The appearance of them indicate that the energy exchanged during
these interactions is in the range of the superconducting energy gap. We also
show that the spin nutation is able to convert the $ac$ Josephson current to a
$dc$ one which is interesting for applications.


title:
A novel SETI strategy targeting the solar focal regions of the most
  nearby stars

abstract:
  Many hypotheses have been raised to explain the famous Fermi paradox. One of
them is that self-replicating probes could have explored the whole Galaxy,
including our Solar System, and that they are still to be detected. In this
scenario, it is proposed here that probes from neighboring stellar systems
could use the stars they orbit as gravitational lenses to communicate
efficiently with each other. Under this hypothesis, a novel SETI approach would
be to monitor the solar focal regions of the most nearby stars to search for
communication devices. The envisioned devices are probably not detectable by
imagery or stellar occultation, but an intensive multi-spectral monitoring
campaign could possibly detect some communication leakages. Another and more
direct option would be to message the focal regions of nearby stars in an
attempt to initiate a reaction.


title:
Coupled magnetic and ferroelectric excitations in
  PbFe_{1/2}Nb_{1/2}O_{3}

abstract:
  A neutron scattering investigation of the magnetoelectric coupling in
PbFe_{1/2}Nb_{1/2}O_{3} (PFN) has been undertaken. Ferroelectric order occurs
below 400 K, as evidenced by the softening with temperature and subsequent
recovery of the zone center transverse optic phonon mode energy (\hbar
\Omega_{0}). Over the same temperature range, magnetic correlations become
resolution limited on a terahertz energy scale. In contrast to the behavior of
nonmagnetic disordered ferroelectrics (namely Pb(Mg,Zn)_{1/3}Nb_{2/3}O_{3}), we
report the observation of a strong deviation from linearity in the temperature
dependence of (\hbar \Omega_{0})^{2}. This deviation is compensated by a
corresponding change in the energy scale of the magnetic excitations, as probed
through the first moment of the inelastic response. The coupling between the
short-range ferroelectric and antiferromagnetic correlations is consistent with
calculations showing that the ferroelectricity is driven by the displacement of
the body centered iron site, illustrating the multiferroic nature of magnetic
lead based relaxors in the dynamical regime.


title:
Using the CMB angular power spectrum to study Dark Matter-photon
  interactions

abstract:
  In this paper, we explore the impact of Dark Matter-photon interactions on
the CMB angular power spectrum. Using the one-year data release of the Planck
satellite, we derive an upper bound on the Dark Matter-photon elastic
scattering cross section of sigma_{DM-photon} < 8 x 10^{-31} (m_DM/GeV) cm^2
(68% CL) if the cross section is constant and a present-day value of
sigma_{DM-photon} < 6 x 10^{-40} (m_DM/GeV) cm^2 (68% CL) if it scales as the
temperature squared. For such a limiting cross section, both the B-modes and
the TT angular power spectrum are suppressed with respect to LCDM predictions
for l > 500 and l > 3000 respectively, indicating that forthcoming data from
CMB polarisation experiments and Planck could help to constrain and
characterise the physics of the dark sector. This essentially initiates a new
type of dark matter search that is independent of whether dark matter is
annihilating, decaying or asymmetric. Thus, any CMB experiment with the ability
to measure the temperature and/or polarisation power spectra at high l should
be able to investigate the potential interactions of dark matter and contribute
to our fundamental understanding of its nature.


title: Linearized FE approximations to a nonlinear gradient flow

abstract:
  We study fully discrete linearized Galerkin finite element approximations to
a nonlinear gradient flow, applications of which can be found in many areas.
Due to the strong nonlinearity of the equation, existing analyses for implicit
schemes require certain restrictions on the time step and no analysis has been
explored for linearized schemes. This paper focuses on the unconditionally
optimal $L^2$ error estimate of a linearized scheme. The key to our analysis is
an iterated sequence of time-discrete elliptic equations and a rigorous
analysis of its solution. We prove the $W^{1,\infty}$ boundedness of the
solution of the time-discrete system and the corresponding FE solution, based
on a more precise estimate of elliptic PDEs in $W^{2,2+\epsilon}$ and a
physical feature of the gradient-dependent diffusion coefficient. Numerical
examples are provided to support our theoretical analysis.


title: Silicon Sheets By Redox Assisted Chemical Exfoliation

abstract:
  In this paper, we report the direct chemical synthesis of silicon sheets in
gram-scale quantities by chemical exfoliation of pre-processed calcium
di-silicide (CaSi2). We have used a combination of X-ray photoelectron
spectroscopy, transmission electron microscopy and Energy-dispersive X-ray
spectroscopy to characterize the obtained silicon sheets. We found that the
clean and crystalline silicon sheets show a 2-dimensional hexagonal graphitic
structure.


title:
On the Existence of a Maximal Cauchy Development for the Einstein
  Equations - a Dezornification

abstract:
  In 1969, Choquet-Bruhat and Geroch established the existence of a unique
maximal globally hyperbolic Cauchy development of given initial data for the
Einstein equations. Their proof, however, has the unsatisfactory feature that
it relies crucially on the axiom of choice in the form of Zorn's lemma. In this
paper we present a proof that avoids the use of Zorn's lemma. In particular, we
provide an explicit construction of this maximal globally hyperbolic
development.


title: On the reducibility of Schlesinger isomonodromic families

abstract:
  We obtain some sufficient conditions for reducibility of a Schlesinger
isomonodromic family with the (block) upper-triangular monodromy to the same
(block) upper-triangular form via a constant gauge transformation. We also
obtain integral representations of hypergeometric type for entries of
upper-triangular solutions of the Schlesinger equation.


title: Interval maps quasi-symmetrically conjugated to a piecewise affine map

abstract:
  Consider a multimodal interval map $f$ of $C^3$ with non-flat critical
points. We establish several characterizations of the map $f$ is
quasi-symmetrically conjugated to a piecewise affine map in the case $f$ is
topologically exact and all of its periodic points are hyperbolic repelling. In
particular, we give a negative answer to a question posted by Henk Bruin in
\cite{Bru96}.


title:
n+1 Dimensional Gravity duals to quantum criticalities with spontaneous
  symmetry breaking

abstract:
  We reexamine the charged AdS domain wall solution to the
Einstein-Abelian-Higgs model proposed by Gubser et al as holographic
superconductors at quantum critical points and comment on their statement about
the uniqueness of gravity solutions. We generalize their explorations from 3+1
dimensions to arbitrary $n+1$Ds and find that the $n+1\geqslant5$D charged AdS
domain walls are unstable against electric perturbations.


title:
Non-Equilibrium Dynamics of a Noisy Quantum Ising Chain: statistics of
  the work and prethermalization after a sudden quench of the transverse field

abstract:
  We discuss the non-equilibrium dynamics of a Quantum Ising Chain (QIC)
following a quantum quench of the transverse field and in the presence of a
gaussian time dependent noise. We discuss the probability distribution of the
work done on the system both for static and dynamic noise. While the effect of
static noise is to smooth the low energy threshold of the statistic of the
work, appearing for sudden quenches, a dynamical noise protocol affects also
the spectral weight of such features. We also provide a detailed derivation of
the kinetic equation for the Green's functions on the Keldysh contour and the
time evolution of observables of physical interest, extending previously
reported results (J. Marino, A. Silva, Phys. Rev. B 86, 060408 (2012)), and
discussing the extension of the concept of prethermalization which can be used
to study noisy quantum many body hamiltonians driven out-of-equilibrium.


title: Molecular states with hidden charm and strange in QCD Sum Rules

abstract:
  This work uses the QCD Sum Rules to study the masses of the $D_s \bar{D}_s^*$
and $D_s^* \bar{D}_s^*$ molecular states with quantum numbers $J^{PC} =
1^{+-}$. Interpolating currents with definite C-parity are employed, and the
contributions up to dimension eight in the Operator Product Expansion (OPE) are
taken into account. The results indicate that two hidden strange
charmonium-like states may exist in the energy ranges of $3.83 \sim 4.13 $ GeV
and $4.22 \sim 4.54 $ GeV, respectively. The hidden strange charmonium-like
states predicted in this work may be accessible in future experiments, e.g.
BESIII, BelleII and SuperB. Possible decay modes, which may be useful in
further research, are predicted.


title: The Equivalence of Grayson and Friedlander-Suslin Spectral Sequences

abstract:
  This thesis establishes the equivalence of Grayson and Friedlander-Suslin
spectral sequences, that was previously only known for the respective
E_2-terms. We develop the necessary techniques regarding K_0-presheaves of
spectra, building on the work of M. Walker and construct certain filtrations on
the K-theory presheaf of spectra that we use as intermediate steps in obtaining
the equivalence of the filtrations.


title:
On Sampling from the Gibbs Distribution with Random Maximum A-Posteriori
  Perturbations

abstract:
  In this paper we describe how MAP inference can be used to sample efficiently
from Gibbs distributions. Specifically, we provide means for drawing either
approximate or unbiased samples from Gibbs' distributions by introducing low
dimensional perturbations and solving the corresponding MAP assignments. Our
approach also leads to new ways to derive lower bounds on partition functions.
We demonstrate empirically that our method excels in the typical "high signal -
high coupling" regime. The setting results in ragged energy landscapes that are
challenging for alternative approaches to sampling and/or lower bounds.


title: Magnetic field dispersion in the neighbourhood of Bok Globules

abstract:
  We performed an observational study of the relation between the interstellar
magnetic field alignment and star formation in twenty (20) sky regions
containing Bok Globules. The presence of young stellar objects in the globules
is verified by a search of infrared sources with spectral energy distribution
compatible with a pre main-sequence star. The interstellar magnetic field
direction is mapped using optical polarimetry. These maps are used to estimate
the dispersion of the interstellar magnetic field direction in each region from
a Gaussian fit, sigma_B. In addition to the Gaussian dispersion, we propose a
new parameter, eta, to measure the magnetic field alignment that does not rely
on any function fitting. Statistical tests show that the dispersion of the
magnetic field direction is different in star forming globules relative to
quiescent globules. Specifically, the less organised magnetic fields occur in
regions having young stellar objects.


title:
A review of modeling applications using ROMS model and COAWST system in
  the Adriatic sea region

abstract:
  From the first implementation in its purely hydrodynamic configuration, to
the last configuration under the Coupled Ocean-Atmosphere-Wave-Sediment
Transport (COAWST) system, several specific modelling applications of the
Regional Ocean Modelling Systems (ROMS, www.myroms.org) have been put forward
within the Adriatic Sea (Italy) region. Covering now a wide range of spatial
and temporal scales, they developed in a growing number of fields supporting
Integrated Coastal Zone Management (ICZM) and Marine Spatial Planning (MSP)
activities in this semi-enclosed sea of paramount importance including the Gulf
of Venice. Presently, a ROMS operational implementation provides every day
hydrodynamic and sea level 3-days forecasts, while a second one models the most
relevant biogeochemical properties, and a third one (two-way coupled with the
Simulating Waves Nearshore (SWAN) model) deals with extreme waves forecast.
Such operational models provide support to civil and environmental protection
activities (e.g., driving sub-models for oil-spill dispersion, storm surge,
coastal morphodynamic changes during storms, saline wedge intrusion along Po
River), in a growing context of stake-holders at regional, national and
international level. Besides, ROMS and COAWST research based activities are
also carried out, mostly aiming at investigating sediment transport, eggs and
larvae dispersion, hypoxic events in the basin; through successive nesting very
high resolutions nearshore the Italian coast can be reached, allowing to
simulate river mouth environments and artificial reefs. Resulting outputs,
written in NetCDF CF compliant format, are delivered via THREDDS Data Server to
a growing number of users around the world.


title:
Unidirectional Lasing Emerging from Frozen Light in Non-Reciprocal
  Cavities

abstract:
  We introduce a class of unidirectional lasing modes associated with the
frozen mode regime of non-reciprocal slow-wave structures. Such asymmetric
modes can only exist in cavities with broken time-reversal and space inversion
symmetries. Their lasing frequency coincides with a spectral stationary
inflection point of the underlying passive structure and is virtually
independent of its size. These unidirectional lasers can be indispensable
components of photonic integrated circuitry.


title: Traffic Jams and Shocks of Molecular Motors inside Cellular Protrusions

abstract:
  Molecular motors are involved in key transport processes inside actin-based
cellular protrusions. The motors carry cargo proteins to the protrusion tip
which participate in regulating the actin polymerization, and play a key role
in facilitating the growth and formation of such protrusions. It is observed
that the motors accumulate at the tips of cellular protrusions, and in addition
form aggregates that are found to drift towards the protrusion base at the rate
of actin treadmilling. We present a one-dimensional driven lattice model, where
motors become inactive after delivering their cargo at the tip, or by loosing
their cargo to a cargo-less neighbor. The results suggest that the experimental
observations may be explained by the formation of traffic jams that form at the
tip. The model is solved using a novel application of mean-field and shock
analysis. We find a new class of shocks that undergo intermittent collapses,
and on average do not obey the Rankine-Hugoniot relation.


title:
Lagrangian kinematics of steep waves up to the inception of a spilling
  breaker

abstract:
  Horizontal Lagrangian velocities and accelerations at the surface of steep
water-waves are studied by Particle Tracking Velocimetry (PTV) for gradually
increasing crest heights up to the inception of a spilling breaker. Localized
steep waves are excited using wavemaker-generated Peregrine breather-type wave
trains. Actual crest and phase velocities are estimated from video recorded
sequences of the instantaneous wave shape as well as from surface elevation
measurements by wave gauges. Effects of nonlinearity and spectral width on
phase velocity, as well as relation between the phase velocity and crest
propagation speed are discussed. The inception of a spilling breaker is
associated with the horizontal velocity of water particles at the crest
attaining that of the crest, thus confirming the kinematic criterion for
inception of breaking.


title: Low-complexity 8-point DCT Approximations Based on Integer Functions

abstract:
  In this paper, we propose a collection of approximations for the 8-point
discrete cosine transform (DCT) based on integer functions. Approximations
could be systematically obtained and several existing approximations were
identified as particular cases. Obtained approximations were compared with the
DCT and assessed in the context of JPEG-like image compression.


title: Resolving the Puzzle of the Pion-Photon Transition Form Factor

abstract:
  We investigate the form factors for pseudoscalar-meson-photon transitions by
means of dispersive QCD sum rules and demonstrate that most of the measurements
done so far (in particular, those by BaBar for $\eta,$ $\eta',$ and $\eta_c$
and those by Belle for $\pi^0$) are, on the one hand, compatible with each
other and with the saturation required by factorization theorems obtained from
perturbative QCD and, on the other hand, give a hint that saturation is
effective already at relatively low momentum transfers $Q^2;$ this hypothesis
is supported by experimental data for the charged-pion elastic form factor
available in the range $Q^2\approx2-4\;\{GeV}^2.$ The only exception are the
BaBar results for the $\pi^0\gamma$ transition form factor, which do not fit
into such picture. We point out that results expected from SHMS at JLab on the
pion elastic form factor in the region $Q^2\approx5-8\;\{GeV}^2$ will provide
the ultimate test of saturation and factorization and strongly impact our
general view of the form factors up to infinitely large $Q^2.$


title:
Isomorphism theorem for Kolmogorov states of $\clb = \dsp{\otimes_{j \in
  \IZ}}\!M^{(j)}_d(\IC)$

abstract:
  We consider the translation dynamics on the $C^*$-algebra $\IM =\otimes_{n
\in \IZ}\!M^{(n)}(\IC)$ of two sided infinite tensor product of $d$ dimensional
matrices $\!M^{(n)}(\IC)=\!M_d(\IC)$ over the field of complex numbers $\IC$
and its restriction to the maximal abelian $C^*$ sub-algebra $\ID^e =
\otimes_{n \in \IZ}\!D_e^{(n)}(\IC)$ of $\IM$, where each
$\!D_e^{(n)}(\IC)=\!D_d(\IC)$ is the algebra of $d$ dimensional diagonal
matrices with respect to an orthonormal basis $e=(e_i)$ of $\IC^d$. We prove
that any two translation invariant Kolmogorov pure states of $\IM$ give
unitarily equivalent dynamics in their Gelfand-Naimark-Segal spaces.
Furthermore, for a class of Kolmogorov pure states of $\IM$ satisfying some
additional invariance, we prove Kolmogorov states give isomorphic translation
dynamics if their restrictions to the maximal abelian $C^*$ sub-algebra $\ID^e$
of $\IM$ are isomorphic. On the other hand, we prove that the translation
dynamics with two infinite tensor product translation invariant faithful states
of $\IM$ are isomorphic if and only if their mean entropies are equal.


title:
Translation invariant pure state on $\otimes_{\IZ}/!M_d(\IC)$ and Haag
  duality

abstract:
  We prove Haag duality property of any translation invariant pure state on
$\clb = \otimes_{\IZ}/!M_d(\IC), \;d \ge 2$, where $/!M_d(\IC)$ is the set of
$d \times d$ dimensional matrices over the field of complex numbers. We also
prove a necessary and sufficient condition for a translation invariant factor
state to be pure on $\clb$.


title: A Birthday Attack on Roulette

abstract:
  A strategy for playing the game of roulette is presented in this paper. The
strategy is based on the same probabilistic argument that leads to the
well-known Birthday Paradox in Probability theory. Following the strategy, a
player will have a positive expected gain per spin as well as in the long run
despite the fact that the pay-off ratios in roulette favor the House.


title:
Identificaci\'on y Registro Catastral de Cuerpos de Agua mediante
  T\'ecnicas de Procesamiento Digital de Imagenes

abstract:
  The effects of global climate change on Peruvian glaciers have brought about
several processes of deglaciation during the last few years. The immediate
effect is the change of size of lakes and rivers. Public institutions that
monitor water resources currently have only recent studies which make up less
than 10% of the total. The effects of climate change and the lack of updated
information intensify social-economic problems related to water resources in
Peru. The objective of this research is to develop a software application to
automate the Cadastral Registry of Water Bodies in Peru, using techniques of
digital image processing, which would provide tools for detection, record,
temporal analysis and visualization of water bodies. The images used are from
the satellite Landsat5, which undergo a pre-processing of calibration and
correction of the satellite. Detection results are archived into a file that
contains location vectors and images of the segmentated bodies of water.


title: On stochastic finite difference schemes

abstract:
  Finite difference schemes in the spatial variable for degenerate stochastic
parabolic PDEs are investigated. Sharp results on the rate of $L_p$ and almost
sure convergence of the finite difference approximations are presented and
results on Richardson extrapolation are established for stochastic parabolic
schemes under smoothness assumptions.


title:
Context-aware recommendations from implicit data via scalable tensor
  factorization

abstract:
  Albeit the implicit feedback based recommendation problem - when only the
user history is available but there are no ratings - is the most typical
setting in real-world applications, it is much less researched than the
explicit feedback case. State-of-the-art algorithms that are efficient on the
explicit case cannot be automatically transformed to the implicit case if
scalability should be maintained. There are few implicit feedback benchmark
data sets, therefore new ideas are usually experimented on explicit benchmarks.
In this paper, we propose a generic context-aware implicit feedback recommender
algorithm, coined iTALS. iTALS applies a fast, ALS-based tensor factorization
learning method that scales linearly with the number of non-zero elements in
the tensor. We also present two approximate and faster variants of iTALS using
coordinate descent and conjugate gradient methods at learning. The method also
allows us to incorporate various contextual information into the model while
maintaining its computational efficiency. We present two context-aware variants
of iTALS incorporating seasonality and item purchase sequentiality into the
model to distinguish user behavior at different time intervals, and product
types with different repetitiveness. Experiments run on six data sets shows
that iTALS clearly outperforms context-unaware models and context aware
baselines, while it is on par with factorization machines (beats 7 times out of
12 cases) both in terms of recall and MAP.


title:
Multifractals of central place systems: models, dimension spectrums, and
  empirical analysis

abstract:
  Central place systems have been demonstrated to possess self-similar patterns
in both the theoretical and empirical perspectives. A central place fractal can
be treated as a monofractal with a single scaling process. However, in the real
world, a system of human settlements is a complex network with multi-scaling
processes. The simple fractal central place models are not enough to interpret
the spatial patterns and evolutive processes of urban systems. It is necessary
to construct multi-scaling fractal models of urban places. Based on the
postulate of intermittent space filling, two typical multifractal models of
central places are proposed in this paper. One model is put forward to reflect
the process of spatial convergence (aggregation), and the generalized
correlation dimension varies from 0.7306 to 1.3181; the other model is
presented to describe the process of spatial divergence (diffusion), the
generalized correlation dimension ranges from 1.6523 to 1.7118. As a case
study, an analogy is drawn between the theoretical models and a system of
cities and towns of Central Plains, China. A finding is that urban systems take
on multifractal form, and can be modeled with multi-scaling fractals. This is a
preliminary attempt to develop the theory of fractal central places, and the
results are helpful for understanding the similarities and differences between
the geographical process of spatial aggregation and that of spatial diffusion.


title: Time irreversible billiards with piecewise-straight trajectories

abstract:
  We introduce a new family of billiards which break time reversal symmetry in
spite of having piece-wise straight trajectories. We show that our billiards
preserve the ergodic and mixing properties of conventional billiards while they
may turn into exponential the power law decay of correlations characteristic of
Sinai type billiards. Such billiards can be implemented by squeezing the
transverse magnetic field along lines or along one-dimensional manifolds.


title: Combinatorial Identities via Two Urn Models

abstract:
  We prove some combinatorial identities using the Polya urn and the closely
related Hoppe urn.


title:
Correcting Multi-focus Images via Simple Standard Deviation for Image
  Fusion

abstract:
  Image fusion is one of the recent trends in image registration which is an
essential field of image processing. The basic principle of this paper is to
fuse multi-focus images using simple statistical standard deviation. Firstly,
the simple standard deviation for the k-by-k window inside each of the
multi-focus images was computed. The contribution in this paper came from the
idea that the focused part inside an image had high details rather than the
unfocused part. Hence, the dispersion between pixels inside the focused part is
higher than the dispersion inside the unfocused part. Secondly, a simple
comparison between the standard deviation for each k-by-k window in the
multi-focus images could be computed. The highest standard deviation between
all the computed standard deviations for the multi-focus images could be
treated as the optimal that is to be placed in the fused image. The
experimental visual results show that the proposed method produces very
satisfactory results in spite of its simplicity.


title: Investigation of Hot QCD Matter: Theoretical Aspects

abstract:
  This lecture presents an overview of the status of the investigation of the
properties of the quark-gluon plasma using relativistic heavy ion collisions at
the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC).
It focuses on the insights that have been obtained by the comparison between
experimental data from both facilities and theoretical calculations.


title:
Non-ergodicity and localization of invariant measure for two colliding
  masses

abstract:
  We show evidence, based on extensive and carefully performed numerical
experiments, that the system of two elastic hard-point masses in one-dimension
is not ergodic for a generic mass ratio and consequently does not follow the
principle of energy equipartition. This system is equivalent to a right
triangular billiard. Remarkably, following the time-dependent probability
distribution in a suitably chosen velocity direction space, we find evidence of
exponential localization of invariant measure. For non-generic mass ratios
which correspond to billiard angles which are rational, or weak irrational
multiples of pi, the system is ergodic, in consistence with existing rigorous
results.

categories: nlin.CD cond-mat.stat-mech math-ph math.MP


title:
Strongly enhanced current densities in Sr0.6K0.4Fe2As2 superconducting
  tapes

abstract:
  Improving transport current has been the primary issue for practical
application of superconducting wires and tapes. However, the porous nature of
powder-in-tube (PIT) processed iron-based superconducting tapes is thought to
be one of the important reasons for the low Jc values. In this work, the
superconducting core density of ex-situ Sr0.6K0.4Fe2As2 tapes was significantly
improved by employing a simple hot pressing as an alternative route for final
sintering. At 4.2 K, the transport Jc values showed excellent values of
5.1x10^4 A/cm^2 at 10 T and 4.3x10^4 A/cm^2 at 14 T, respectively, which attain
the Jc level desired for practical applications. Moreover, the Jc values
exhibited extremely weak magnetic field dependence. These results clearly
demonstrate that PIT pnictide wire conductors are very promising for high field
magnet applications.


title: Optimal Control for Burgers Equation using Particle Methods

abstract:
  This papers shows the convergence of optimal control problems where the
constraint function is discretised by a particle method. In particular, we
investigate the viscous Burgers equation in the whole space $\mathbb R$ by
using distributional particle approximations. The continuous optimisation
problem is derived and investigated. Then, the discretisation of the state
constraint and the resulting adjoint equation is performed and convergence
rates are derived. Moreover, the existence of a converging subsequence of
control functions, obtained by the discrete control problem, is shown. Finally,
the derived rates are verified numerically.


title: Syntomic cohomology and regulators for varieties over p-adic fields

abstract:
  We show that the logarithmic version of the syntomic cohomology of Fontaine
and Messing for semistable varieties over $p$-adic rings extends uniquely to a
cohomology theory for varieties over $p$-adic fields that satisfies
$h$-descent. This new cohomology - syntomic cohomology - is a Bloch-Ogus
cohomology theory, admits period map to \'etale cohomology, and has a syntomic
descent spectral sequence (from an algebraic closure of the given field to the
field itself) that is compatible with the Hochschild-Serre spectral sequence on
the \'etale side. In relative dimension zero we recover the potentially
semistable Selmer groups and, as an application, we prove that Soul\'e's
\'etale regulators land in the potentially semistable Selmer groups.
  Our construction of syntomic cohomology is based on new ideas and techniques
developed by Beilinson and Bhatt in their recent work on $p$-adic comparison


title: Gaussian risk models with financial constraints

abstract:
  In this paper we investigate Gaussian risk models which include financial
elements such as inflation and interest rates. For some general models for
inflation and interest rates, we obtain an asymptotic expansion of the
finite-time ruin probability for Gaussian risk models. Furthermore, we derive
an approximation of the conditional ruin time by an exponential random variable
as the initial capital tends to infinity.


title:
Toric ideals with linear components: an algebraic interpretation of
  clustering the cells of a contingency table

abstract:
  In this paper we show that the agglomeration of rows or columns of a
contingency table with a hierarchical clustering algorithm yields statistical
models defined through toric ideals. In particular, starting from the classical
independence model, the agglomeration process adds a linear part to the toric
ideal generated by the $2 \times 2$ minors.


title:
On the Absence of Broad Forbidden Emission Lines in the Low Luminosity
  Seyfert 1 Nucleus of NGC 3227

abstract:
  The absence of broad [O III] ${\lambda\lambda}$4959,5007 forbidden emission
lines is one of the key arguments cited in the published literature for the gas
density exceeding the critical density; 7 ${\times}$ 10$^5$ cm$^{-3}$, in the
broad line region (BLR) of active galactic nuclei. However, for NGC 3227, an
equally valid alternative explanation is that O$^{2+}$ is progressively ionized
to O$^{3+}$ as the central UV-X-ray source is approached. Observational
evidence for such an ionization gradient is provided by spectra obtained with
the Space Telescope Imaging Spectrograph. Modeling the rich UV-visible spectrum
of NGC 3227 with the photoionization code Cloudy supports the interpretation
that the absence of broad [O III] forbidden emission lines is due to
ionization, rather than high gas density, and further suggests that what we
perceive as the BLR in NGC 3227 is just the illuminated portion of a much
larger inflow. The low metallicity deduced for the inflowing gas suggests an
origin in the circumgalactic medium.


title:
Boundary non-crossing probabilities for fractional Brownian motion with
  trend

abstract:
  In this paper we investigate the boundary non-crossing probabilities of a
fractional Brownian motion considering some general deterministic trend
function. We derive bounds for non-crossing probabilities and discuss the case
of a large trend function. As a by-product we solve a minimization problem
related to the norm of the trend function.


title: Vector transform operators for piece-wise harmonic functions

abstract:
  The vector transform operators are investigated; these operators are used at
the solution of boundary value problems in piecewise homogeneous spherically
symmetric areas. In particular, examples of transformation operators for vector
boundary value problems are given for third vector boundary value problem in
the unit circle and for the Dirichlet problem in the unit circle.


title:
The dynamics of technology diffusion and the impacts of climate policy
  instruments in the decarbonisation of the global electricity sector

abstract:
  This paper presents an analysis of climate policy instruments for the
decarbonisation of the global electricity sector in a non-equilibrium economic
and technology diffusion perspective. Energy markets are driven by innovation,
path-dependent technology choices and diffusion. However, conventional
optimisation models lack detail on these aspects and have limited ability to
address the effectiveness of policy interventions because they do not represent
decision-making. As a result, known effects of technology lock-ins are liable
to be underestimated. In contrast, our approach places investor decision-making
at the core of the analysis and investigates how it drives the diffusion of
low-carbon technology in a highly disaggregated, hybrid, global
macroeconometric model, FTT:Power-E3MG. Ten scenarios to 2050 of the
electricity sector in 21 regions exploring combinations of electricity policy
instruments are analysed, including their climate impacts. We show that in a
diffusion and path-dependent perspective, the impact of combinations of
policies does not correspond to the sum of impacts of individual instruments:
synergies exist between policy tools. We argue that the carbon price required
to break the current fossil technology lock-in can be much lower when combined
with other policies, and that a 90% decarbonisation of the electricity sector
by 2050 is affordable without early scrapping.


title: A class of Toeplitz operators with hypercyclic subspaces

abstract:
  We use a theorem by Gonzalez, Leon-Saavedra and Montes-Rodriguez to construct
a class of coanalytic Toeplitz operators which have an infinite-dimensional
closed subspace, where any non-zero vector is hypercyclic.


title: Geometric phase of neutrino propagating through dissipative matter

abstract:
  We study the geometric phase (GP) in neutrino oscillation for both Dirac and
Majorana neutrinos. We apply the kinematic generalization of the GP to quantum
open systems that take into account the coupling to a dissipative environment.
In the dissipationless case, the GP does not depend on the Majorana angle. It
is not the case in the presence of dissipation and hence the GP can serve as a
tool determining the type of the Dirac vs the Majorana neutrino.


title: Simulating gamma-ray binaries with a relativistic extension of RAMSES

abstract:
  Gamma-ray binaries are composed of a massive star and a rotation-powered
pulsar with a highly relativistic wind. The collision between the winds from
both objects creates a shock structure where particles are accelerated,
resulting in the observed high energy emission. We study the impact of special
relativity on the structure and stability of the colliding wind region and
highlight the differences with colliding winds from massive stars. We focus on
evolution with increasing values of the Lorentz factor of the pulsar wind,
keeping in mind that current simulations are unable to reach the expected
values of the pulsar wind Lorentz factors by orders of magnitude. We use high
resolution numerical simulations with a relativistic extension to the
hydrodynamics code RAMSES we have developed. Using 2D simulations, we focus on
the region close to the binary, neglecting orbital motion. We use different
values of the Lorentz factor of the pulsar wind, up to 16. We find analytic
scaling relations between stellar wind collisions and gamma-ray binaries. They
provide the position of the contact discontinuity. The position of the shocks
strongly depends on the Lorentz factor, the relativistic wind is more
collimated than expected based on non-relativistic simulations. Beyond a
certain distance, the shocked flow is accelerated to its initial velocity and
follows adiabatic expansion. We provide guidance for extrapolation towards more
realistic values of the Lorentz factor of the pulsar wind. We extended the
adaptive mesh refinement code RAMSES to relativistic hydrodynamics. This code
is suited for the study of astrophysical objects such as pulsar wind nebulae,
gamma-ray bursts or relativistic jets and will be part of the next public
release of RAMSES. Using this code we performed simulations of gamma-ray
binaries, highlighting the limits and possibilities of current hydrodynamic
models of such systems.


title: Robust Graph Ideals

abstract:
  Let I be a toric ideal. We say I is robust if its universal Groebner basis is
a minimal generating set. We show that any robust toric ideal arising from a
graph G is also minimally generated by its Graver basis. We then completely
characterize all graphs which give rise to robust ideals. Our characterization
shows that robustness can be determined solely in terms of graph-theoretic
conditions on the set of circuits of G.


title:
Magnetic Properties of Two-dimensional Nanodots: Ground State and Phase
  Transition

abstract:
  We study the effect of perpendicular single-ion anisotropy,
$-As_{\text{z}}^2$, on the ground-state structure and finite-temperature
properties of a two-dimensional magnetic nanodot in presence of a dipolar
interaction of strength $D$. By a simulated annealing Monte Carlo method, we
show that in the ground state a vortex core perpendicular to the nanodot plane
emerges already in the range of moderate anisotropy values above a certain
threshold level. In the giant-anisotropy regime the vortex structure is
superseded by a stripe domain structure with stripes of alternate domains
perpendicular to the surface of the sample. We have also observed an
intermediate stage between the vortex and stripe structures, with satellite
regions of tilted nonzero perpendicular magnetization around the core. At
finite temperatures, at small $A$, we show by Monte Carlo simulations that
there is a transition from the the in-plane vortex phase to the disordered
phase characterized by a peak in the specific heat and the vanishing vortex
order parameter. At stronger $A$, we observe a discontinuous transition with a
large latent heat from the in-plane vortex phase to perpendicular stripe
ordering phase before a total disordering at higher temperatures. In the regime
of perpendicular stripe domains, namely with giant $A$, there is no phase
transition at finite $T$: the stripe domains are progressively disordered with
increasing $T$. Finite-size effects are shown and discussed.


title: Topological Bragg Peaks And How They Characterise Point Sets

abstract:
  Bragg peaks in point set diffraction show up as eigenvalues of a dynamical
system. Topological Bragg peaks arrise from topological eigenvalues and
determine the torus parametrisation of the point set. We will discuss how
qualitative properties of the torus parametrisation characterise the point set.


title:
A Discontinuous Galerkin like Coarse Space correction for Domain
  Decomposition Methods with continuous local spaces : the DCS-DGLC Algorithm

abstract:
  In this paper, we are interested in scalable Domain Decomposition Methods
(DDM). To this end, we introduce and study a new Coarse Space Correction
algorithm for Optimized Schwarz Methods(OSM) : the DCS-DGLC algorithm. The main
idea is to use a Discontinuous Galerkin like formulation to compute a
discontinuous coarse space correction. While the local spaces remain
continuous, the coarse space should be discontinuous to compensate the
discontinuities introduced by the OSM at the interface between neighboring
subdomains. The discontinuous coarse correction algorithm can not only be used
with OSM but also be used with any one-level DDM that produce discontinuous
iterates. While ideas from Discontinuous Galerkin(DG) are used in the
computation of the coarse correction, the final aim of the DCS-DGLC algorithm
is to compute in parallel the discrete solution to the classical non-DG finite
element problem.


title: Existence, uniqueness and decay rates for evolution equations on trees

abstract:
  We study evolution equations governed by an averaging operator on a directed
tree, showing existence and uniqueness of solutions. In addition we find
conditions of the initial condition that allows us to find the asymptotic decay
rate of the solutions as $t\to \infty$. It turns out that this decay rate is
not uniform, it strongly depends on how the initial condition goes to zero as
one goes down in the tree.


title: $\natural$-model with jumps

abstract:
  We consider the so-called $\natural$-model. It is an one-default model which
gives the conditional law of a random time with respect to a reference
filtration. This model has been studied in the case where the parameters are
continuous. In this paper we will establish the $\natural$-model in the case of
jump parameters. We then prove the corresponding enlargement of filtration
formula and we compute the derivative of the conditional distribution functions
of the random time.


title: Multiplicity of A-type and related stars

abstract:
  The origin of chemically peculiar stars remains enigmatic, especially
regarding their frequency among their "normal" peers. In addition to magnetic
fields and rotation, multiplicity may shed light on the question. We mention
the main surveys of the three kinds performed so far of intermediate mass
stars, either normal or chemically peculiar, magnetic or not: imaging,
spectroscopic, and photometric. We also consider the mulitiplicity of red giant
stars, since many of them are descendants of A-type stars, through Mermilliod's
radial velocity monitoring of open cluster members. We briefly review the
orbital properties of binary systems hosting chemically peculiar stars. Some
specific objects of special interest are mentioned as deserving further study.
Finally, we recall that some binary systems composed of A-type stars are
progenitors of Type Ia supernovae, and evoke the potentialities of future
surveys like Gaia.


title: Dielectric Laser Acceleration

abstract:
  We describe recent advances in the study of particle acceleration using
dielectric near-field structures driven by infrared lasers, which we refer to
as Dielectric Laser Accelerators. Implications for high energy physics and
other applications are discussed.


title: Magnetic shield of PMT used in DAMPE electromagnetic calorimeter

abstract:
  The magnetic characteristics of photomultiplier tube R5610A-01 are studied in
this paper. The experimental data shows that the gain of R5610A-01 loses about
53% when the magnetic field is 3G along its +X axis. A cylinder of one-layer
permalloy strip is able to reduce the effect of 3G magnetic field on the PMT's
gain to less than 1%.


title: Low-energy R-parity violating SUSY with horizontal flavor symmetries

abstract:
  In this talk, I will present the general structure of RPV couplings when a
Froggatt-Nielsen horizontal symmetry is responsible for the flavor structure of
both the SM and the MSSM. For sub-TeV ({\it natural}) SUSY, lepton number must
be an accidental symmetry, while low-energy SUSY is still allowed by baryonic
RPV, which lowers the MET signature of superparticles decays. The largest RPV
coupling involves the stop, and it is constrained between $10^{-3}$ (from
FCNCs) and $10^{-9}$ (from LHC searches).


title: An Efficient Authorship Protection Scheme for Shared Multimedia Content

abstract:
  Many electronic content providers today like Flickr and Google, offer space
to users to publish their electronic media (e.g. photos and videos) in their
cloud infrastructures, so that they can be publicly accessed. Features like
including other information, such as keywords or owner information into the
digital material is already offered by existing providers. Despite the useful
features made available to users by such infrastructures, the authorship of the
published content is not protected against various attacks such as compression.
In this paper we propose a robust scheme that uses digital invisible
watermarking and hashing to protect the authorship of the digital content and
provide resistance against malicious manipulation of multimedia content. The
scheme is enhanced by an algorithm called MMBEC, that is an extension of an
established scheme MBEC, towards higher resistance.


title:
A building-theoretic approach to relative Tamagawa numbers of
  quasi-split semisimple groups over global function fields

abstract:
  Let G be a semisimple quasi-split group defined over a global function field.
We express the relative Tamagawa number of G in terms of local data including
the number of types of special vertices in one orbit of the Bruhat-Tits
building over some completion with respect to a place and the class number of G
at that place.


title: On the Localisation of 4-Dimensional Brane-World Black Holes

abstract:
  In the context of brane-world models, we pursue the question of the existence
of 5-dimensional solutions describing regular black holes localised close to
the brane. Employing a perturbed Vaidya-type line-element embedded in a warped
fifth dimension, we attempt to localise the extended black-string singularity,
and to restore the regularity of the AdS spacetime at a finite distance from
the brane by introducing an appropriate bulk energy-momentum tensor. As a
source for this bulk matter, we are considering a variety of non-ordinary
field-theory models of scalar fields either minimally-coupled to gravity, but
including non-canonical kinetic terms, mixing terms, derivative interactions
and ghosts, or non-minimally-coupled to gravity through a general coupling to
the Ricci scalar. In all models considered, even in the ones characterised by a
high-degree of flexibility, a negative result was reached. Our analysis
demonstrates how difficult the analytic construction of a localised brane-world
black hole may be in the context of a well-defined field-theory model. Finally,
with regard to the question of the existence or not of a static classical black
hole solution on the brane, our analysis suggests that such solutions could in
principle exist, however, the associated field configuration itself has to be
dynamic.


title:
Rotationally Invariant Image Representation for Viewing Direction
  Classification in Cryo-EM

abstract:
  We introduce a new rotationally invariant viewing angle classification method
for identifying, among a large number of Cryo-EM projection images, similar
views without prior knowledge of the molecule. Our rotationally invariant
features are based on the bispectrum. Each image is denoised and compressed
using steerable principal component analysis (PCA) such that rotating an image
is equivalent to phase shifting the expansion coefficients. Thus we are able to
extend the theory of bispectrum of 1D periodic signals to 2D images. The
randomized PCA algorithm is then used to efficiently reduce the dimensionality
of the bispectrum coefficients, enabling fast computation of the similarity
between any pair of images. The nearest neighbors provide an initial
classification of similar viewing angles. In this way, rotational alignment is
only performed for images with their nearest neighbors. The initial nearest
neighbor classification and alignment are further improved by a new
classification method called vector diffusion maps. Our pipeline for viewing
angle classification and alignment is experimentally shown to be faster and
more accurate than reference-free alignment with rotationally invariant K-means
clustering, MSA/MRA 2D classification, and their modern approximations.


title: Rapidity evolution of Wilson lines at the next-to-leading order

abstract:
  At high energies particles move very fast so the proper degrees of freedom
for the fast gluons moving along the straight lines are Wilson-line operators -
infinite gauge factors ordered along the line. In the framework of operator
expansion in Wilson lines the energy dependence of the amplitudes is determined
by the rapidity evolution of Wilson lines. We present the next-to-leading order
hierarchy of the evolution equations for Wilson-line operators.


title: Return to the Poissonian City

abstract:
  Consider the following random spatial network: in a large disk, construct a
network using a stationary and isotropic Poisson line process of unit
intensity. Connect pairs of points using the network, with initial / final
segments of the connecting path formed by travelling off the network in the
opposite direction to that of the destination / source. Suppose further that
connections are established using "near-geodesics", constructed between pairs
of points using the perimeter of the cell containing these two points and
formed using only the Poisson lines not separating them. If each pair of points
generates an infinitesimal amount of traffic divided equally between the two
connecting near-geodesics, and if the Poisson line pattern is conditioned to
contain a line through the centre, then what can be said about the total flow
through the centre? In earlier work ("Geodesics and flows in a Poissonian
city", Annals of Applied Probability, 21(3), 801--842, 2011) it was shown that
a scaled version of this flow had asymptotic distribution given by the 4-volume
of a region in 4-space, constructed using an improper anisotropic Poisson line
process in an infinite planar strip. Here we construct a more amenable
representation in terms of two "seminal curves" defined by the improper Poisson
line process, and establish results which produce a framework for effective
simulation from this distribution up to an L1 error which tends to zero with
increasing computational effort.


title: Study on the temperature dependence of BGO light yield

abstract:
  The temperature dependence of BGO coupled with photomultiplier tube R5610A-01
was studied in the range of -30{\deg}C~30{\deg}C. The temperature coefficient
of the BGO and R5610A in whole was tested to be -1.82%. And the temperature
coefficient of the gain of the R5610A is -0.44% which was tested in the same
situation using a blue LED. Thus the temperature coefficient of BGO's light
yield can be evaluated as -1.38%.


title:
PROSPECT - A Precision Reactor Oscillation and Spectrum Experiment at
  Short Baselines

abstract:
  Current models of antineutrino production in nuclear reactors predict
detection rates and spectra at odds with the existing body of direct reactor
antineutrino measurements. High-resolution antineutrino detectors operated
close to compact research reactor cores can produce new precision measurements
useful in testing explanations for these observed discrepancies involving
underlying nuclear or new physics. Absolute measurement of the 235U-produced
antineutrino spectrum can provide additional constraints for evaluating the
accuracy of current and future reactor models, while relative measurements of
spectral distortion between differing baselines can be used to search for
oscillations arising from the existence of eV-scale sterile neutrinos. Such a
measurement can be performed in the United States at several highly-enriched
uranium fueled research reactors using near-surface segmented liquid
scintillator detectors. We describe here the conceptual design and physics
potential of the PROSPECT experiment, a U.S.-based, multi-phase experiment with
reactor-detector baselines of 7-20 meters capable of addressing these and other
physics and detector development goals. Current R&D status and future plans for
PROSPECT detector deployment and data-taking at the High Flux Isotope Reactor
at Oak Ridge National Laboratory will be discussed.


title:
Harmonic Forms on Manifolds with Non-Negative Bakry-\'Emery-Ricci
  Curvature

abstract:
  In this paper we prove that on a complete smooth metric measure space with
non-negative Bakry-\'Emery-Ricci curvature if the space of weighted L^2
harmonic one-forms is non-trivial then the weighted volume of the manifold is
finite and universal cover of the manifold splits isometrically as the product
of the real line with an hypersurface.


title: Quasi-Banach spaces of almost universal disposition

abstract:
  We show that for each $p\in(0,1]$ there exists a separable $p$-Banach space
$\mathbb G_p$ of almost universal disposition, that is, having the following
extension property: for each $\epsilon>0$ and each isometric embedding $g:X\to
Y$, where $Y$ is a finite dimensional $p$-Banach space and $X$ is a subspace of
$\mathbb G_p$, there is an $\epsilon$-isometry $f:Y\to \mathbb G_p$ such that
$x=f(g(x))$ for all $x\in X$.
  Such a space is unique, up to isometries, does contain an isometric copy of
each separable $p$-Banach space and has the remarkable property of being
"locally injective" amongst $p$-Banach spaces.
  We also present a nonseparable generalization which is of universal
disposition for separable spaces and "separably injective". No separably
injective $p$-Banach space was previously known for $p<1$.


title:
Genuinely multi-point temporal quantum correlations and universal
  measurement-based quantum computing

abstract:
  We introduce a constructive procedure that maps all spatial correlations of a
broad class of states into temporal correlations between general quantum
measurements. This allows us to present temporal phenomena analogous to
genuinely multipartite nonlocal phenomena, such as Greenberger-Horne-Zeilinger
correlations, which do not exist if only projective measurements on qubits are
considered. The map is applied to certain lattice systems in order to replace
one spatial dimension with a temporal one, without affecting measured
correlations. We use this map to show how repeated application of a
1d-cluster-gate leads to universal one-way quantum computing when supplemented
with the general measurements.


title: One of the most massive stars in the Galaxy may have formed in isolation

abstract:
  Very massive stars, 100 times heavier than the sun, are rare. It is not yet
known whether such stars can form in isolation or only in star clusters. The
answer to this question is of fundamental importance. The central region of our
Galaxy is ideal for investigating very massive stars and clusters located in
the same environment. We used archival infrared images to investigate the
surroundings of apparently isolated massive stars presently known in the
Galactic Center. We find that two such isolated massive stars display apparent
bow shocks and hence may be "runaways" from their birthplace. Thus, some
isolated massive stars in the Galactic Center region might have been born in
star clusters known in this region. However, no bow shock is detected around
the isolated star WR102ka (Peony nebula star), which is one of the most massive
and luminous stars in the Galaxy. This star is located at the center of an
associated dusty circumstellar nebula. To study whether a star cluster may be
"hidden" in the surroundings of WR102ka, to obtain new and better spectra of
this star, and to measure its radial velocity, we obtained observations with
the integral-field spectrograph SINFONI at the ESO's Very Large Telescope
(VLT). Our observations confirm that WR102ka is one of the most massive stars
in the Galaxy and reveal that this star is not associated with a star cluster.
We suggest that WR102ka has been born in relative isolation, outside of any
massive star cluster.


title:
Polarization properties of photospheric emission from relativistic,
  collimated outflows

abstract:
  We consider the polarization properties of photospheric emission originating
in jets consisting of a highly relativistic core of opening angle theta_j and
Lorentz factor Gamma_0, and a surrounding shear layer where the Lorentz factor
is decreasing as a power law of index p with angle from the jet axis. We find
significant degrees of linear polarization for observers located at viewing
angles theta_v \gtrsim theta_j. In particular, the polarization degree of
emission from narrow jets (theta_j \approx 1/Gamma_0) with steep Lorentz factor
gradients (p \gtrsim 4) reaches \sim 40%. The angle of polarization may shift
by pi/2 for time-variable jets. The spectrum below the thermal peak of the
polarized emission appears non-thermal due to aberration of light, without the
need for additional radiative processes or energy dissipation. Furthermore,
above the thermal peak a power law of photons forms due to Comptonization of
photons that repeatedly scatter between regions of different Lorentz factor
before escaping. We show that polarization degrees of a few tens of percent and
broken power law spectra are natural in the context of photospheric emission
from structured jets. Applying the model to gamma-ray bursts, we discuss
expected correlations between the spectral shape and the polarization degree of
the prompt emission.


title: The CP-violating pMSSM at the Intensity Frontier

abstract:
  In this Snowmass whitepaper, we describe the impact of ongoing and proposed
intensity frontier experiments on the parameter space of the Minimally
Supersymmetric Standard Model (MSSM). We extend a set of phenomenological MSSM
(pMSSM) models to include non-zero CP-violating phases and study the
sensitivity of various flavor observables in these scenarios Future electric
dipole moment and rare meson decay experiments can have a strong impact on the
viability of these models that is relatively independent of the detailed
superpartner spectrum. In particular, we find that these experiments have the
potential to probe models that are expected to escape searches at the
high-luminosity LHC.


title: Constraining Stellar Winds of Young Sun-like Stars

abstract:
  As part of the project Pathways to Habitability (http://path.univie.ac.at/),
we study the properties of the stellar winds of low-mass and Sun-like stars,
and their influences on the atmospheres of potentially habitable planets. For
this purpose, we combine mapping of stellar magnetic fields with
magnetohydrodynamic wind models.


title: Scattering of gap solitons by PT-symmetric defects

abstract:
  The resonant scattering of gap solitons (GS) of the periodic nonlinear
Schr\"odinger equation with a localized defect which is symmetric under the
parity and the time-reversal (PT) symmetry, is investigated. It is shown that
for suitable amplitudes ratios of the real and imaginary parts of the defect
potential the resonant transmission of the GS through the defect becomes
possible. The resonances occur for potential parameters which allow the
existence of localized defect modes with the same energy and norm of the
incoming GS. Scattering properties of GSs of different band-gaps with effective
masses of opposite sign are investigated. The possibility of unidirectional
transmission and blockage of GSs by PT defect, as well as, amplification and
destruction induced by multiple reflections from two PT defects, are also
discussed.

categories: nlin.PS cond-mat.quant-gas physics.atom-ph physics.optics


title: Degenerate and dihedral Heun functions with parameters

abstract:
  Just as with the Gauss hypergeometric function, particular cases of the local
Heun function can be Liouvillian (that is, "elementary") functions. One way to
obtain these functions is by pull-back transformations of Gauss hypergeometric
equations with Liouvillian solutions. This paper presents the Liouvillian
solutions of Heun's equations that are pull-backs of the parametric
hypergeometric equations with cyclic or dihedral monodromy groups.


title:
Exponential integrability properties of numerical approximation
  processes for nonlinear stochastic differential equations

abstract:
  Exponential integrability properties of numerical approximations are a key
tool for establishing positive rates of strong and numerically weak convergence
for a large class of nonlinear stochastic differential equations. It turns out
that well-known numerical approximation processes such as Euler-Maruyama
approximations, linear-implicit Euler approximations, and some tamed Euler
approximations from the literature rarely preserve exponential integrability
properties of the exact solution. The main contribution of this article is to
identify a class of stopped increment-tamed Euler approximations which preserve
exponential integrability properties of the exact solution under minor
additional assumptions on the involved functions.


title:
The Discrepancy in Modelling of Galactic Cosmic Ray Primaries and
  Secondaries

abstract:
  Given that the bulk of the galactic cosmic rays (CRs) originates from
transient point-like sources, such as supernova remnants, the flux of the CR
primary component measured at Earth depends on the local source history.
Whereas the secondary omponent shows little to no variation due to nearby
sources, and instead, should depend on the global distribution of CRs.
Steady-state, rotational symmetric models (2D) of CR propagation assume
smeared-out CR sources in the Galaxy and cannot properly take into account the
influence of nearby point sources. In this paper, we infer evidence of nearby
sources by illustrating that a 2D propagation model will not describe CR
primaries and secondaries equally well. We adapted the 2D version of the
GALPROP code to a compute-cluster environment and perform parameter studies
comparing CR spectra with primary and secondary CR data separately. Doing a
parameter study, one may expect different best fit values looking at the
primary and secondary CR components separately, as it is unlikely that the
source history mimicked by the 2D models coincides with the real local source
history. We find that the primaries and secondaries are fitted with differing
best fit parameters, with the results indicating that the 2D model being more
suited to modelling secondary CRs. The insufficient modelling of primary CRs
can be contributed to the possible presence of local CR sources.


title: Algebraic geometry and stability for integrable systems

abstract:
  In 1970s, a method was developed for integration of nonlinear equations by
means of algebraic geometry. Starting from a Lax representation with spectral
parameter, the algebro-geometric method allows to solve the system explicitly
in terms of theta functions of Riemann surfaces. However, the explicit formulas
obtained in this way fail to answer qualitative questions such as whether a
given singular solution is stable or not. In the present paper, the problem of
stability for equilibrium points is considered, and it is shown that this
problem can also be approached by means of algebraic geometry.


title: The Large-scale Distribution of Cool Gas around Luminous Red Galaxies

abstract:
  We present a measurement of the correlation function between luminous red
galaxies and cool gas traced by Mg II \lambda \lambda 2796, 2803 absorption, on
scales ranging from about 30 kpc to 20 Mpc. The measurement is based on
cross-correlating the positions of about one million red galaxies at z~0.5 and
the flux decrements induced in the spectra of about 10^5 background quasars
from the Sloan Digital Sky Survey. We find that: (i) This galaxy-gas
correlation reveals a change of slope on scales of about 1 Mpc, consistent with
the expected transition from a dark matter halo dominated environment to a
regime where clustering is dominated by halo-halo correlations. Assuming that,
on average, the distribution of Mg II gas follows that of dark matter up to a
gas-to-mass ratio, we find the standard halo model to provide an accurate
description of the gas distribution over three orders of magnitude in scale.
Within this framework we estimate the average host halo mass of luminous red
galaxies to be about 10^{13.5} M_solar, in agreement with other methods. We
also find the Mg II gas-to-mass ratio around LRGs to be consistent with the
cosmic value estimated on Mpc scales. Combining our galaxy-gas correlation and
the galaxy-mass correlation function from galaxy-galaxy lensing analyses we can
directly measure the Mg II gas-to-mass ratio as a function of scale and reach
the same conclusion. (ii) From line-width estimates, we show that the velocity
dispersion of the gas clouds also shows the expected 1- and 2-halo behaviors.
On large scales the gas distribution follows the Hubble flow, whereas on small
scales we observe the velocity dispersion of the Mg II gas clouds to be lower
than that of collisionless dark matter particles within their host halo. This
is in line with the fact that cool clouds are subject to the pressure of the
virialized hot gas.


title: On \pi-surfaces of four-dimensional parallelohedra

abstract:
  We show that every four-dimensional parallelohedron P satisfies a recently
found condition of Garber, Gavrilyuk & Magazinov sufficient for the Voronoi
conjecture being true for P. Namely we show that for every four-dimensional
parallelohedron P the group of rational first homologies of its \pi-surface is
generated by half-belt cycles.


title:
Character varieties with Zariski closures of GL_n-conjugacy classes at
  punctures

abstract:
  In a previous paper (joint with Hausel and Rodriguez-Villegas) we gave a
conjectural formula for the mixed Hodge polynomials of character varieties with
generic semisimple conjugacy classes at punctures and we prove a formula for
the E-polynomial. We also proved that these character varieties are
irreducible. In this paper we extend the above results to character varieties
with Zariski closures of arbitrary generic conjugacy classes at punctures
working with intersection cohomology. We also study Weyl group action on the
intersection cohomology of the partial resolutions of these character varieties
and give a conjectural formula for the two-variables polynomials that encode
the trace of the elements of the Weyl group on the subquotients of the weight
filtration. Finally, we compute the generating function of the stack count of
character varieties with Zariski closure of unipotent regular conjugacy class
at punctures.


title:
Morita equivalence and Morita invariant properties. Applications in the
  context of Leavitt path algebras

abstract:
  In this paper we prove that two idempotent rings are Morita equivalent if
every corner of one of them is isomorphic to a corner of a matrix ring of the
other one. We establish the converse (which is not true in general) for
$\sigma$-unital rings having a $\sigma$-unit consisting of von Neumann regular
elements. The following aim is to show that a property is Morita invariant if
it is invariant under taking corners and under taking matrices. The previous
results are used to check the Morita invariance of certain ring properties
(being locally left/right artinian/noetherian, being categorically left/right
artinian, being an $I_0$-ring and being properly purely infinite) and certain
graph properties in the context of Leavitt path algebras (Condition (L),
Condition (K) and cofinality). A different proof of the fact that a graph with
an infinite emitter does not admit any desingularization is also given.


title: Imaging strong localized scatterers with sparsity promoting optimization

abstract:
  We study active array imaging of small but strong scatterers in homogeneous
media when multiple scattering between them is important. We use the Foldy-Lax
equations to model wave propagation with multiple scattering when the
scatterers are small relative to the wavelength. In active array imaging we
seek to locate the positions and reflectivities of the scatterers, that is, to
determine the support of the reflectivity vector and the values of its nonzero
elements from echoes recorded on the array. This is a nonlinear inverse problem
because of the multiple scattering. We show in this paper how to avoid the
nonlinearity and form images non-iteratively through a two-step process which
involves $\ell_1$ norm minimization. However, under certain illuminations
imaging may be affected by screening, where some scatterers are obscured by
multiple scattering. This problem can be mitigated by using multiple and
diverse illuminations. In this case, we determine solution vectors that have a
common support. The uniqueness and stability of the support of the reflectivity
vector obtained with single or multiple illuminations are analyzed, showing
that the errors are proportional to the amount of noise in the data with a
proportionality factor dependent on the sparsity of the solution and the mutual
coherence of the sensing matrix, which is determined by the geometry of the
imaging array. Finally, to filter out noise and improve the resolution of the
images, we propose an approach that combines optimal illuminations using the
singular value decomposition of the response matrix together with sparsity
promoting optimization jointly for all illuminations. This work is an extension
of our previous paper [5] on imaging using optimization techniques where we now
account for multiple scattering effects.


title: Group-theoretic structure of linear phase multirate filter banks

abstract:
  Unique lifting factorization results for group lifting structures are used to
characterize the group-theoretic structure of two-channel linear phase FIR
perfect reconstruction filter bank groups. For D-invariant, order-increasing
group lifting structures, it is shown that the associated lifting cascade group
C is isomorphic to the free product of the upper and lower triangular lifting
matrix groups. Under the same hypotheses, the associated scaled lifting group S
is the semidirect product of C by the diagonal gain scaling matrix group D.
These results apply to the group lifting structures for the two principal
classes of linear phase perfect reconstruction filter banks, the whole- and
half-sample symmetric classes. Since the unimodular whole-sample symmetric
class forms a group, W, that is in fact equal to its own scaled lifting group,
W=S_W, the results of this paper characterize the group-theoretic structure of
W up to isomorphism. Although the half-sample symmetric class H does not form a
group, it can be partitioned into cosets of its lifting cascade group, C_H, or,
alternatively, into cosets of its scaled lifting group, S_H. Homomorphic
comparisons reveal that scaled lifting groups covered by the results in this
paper have a structure analogous to a "noncommutative vector space."


title:
Dynamic Sliding Mode Control based on Fractional calculus subject to
  uncertain delay based chaotic pneumatic robot

abstract:
  This paper considers the chattering problem of sliding mode control while
delay in robot manipulator caused chaos in such electromechanical systems.
Fractional calculus as a powerful theorem to produce a novel sliding mode;
which has a dynamic essence is used for chattering elimination. To realize the
control of a class of chaotic systems in master-slave configuration this novel
fractional dynamic sliding mode control scheme is presented and examined on
delay based chaotic robot in joint and work space. Also the stability of the
closed-loop system is guaranteed by Lyapunov stability theory. Beside these,
delayed robot motions are sorted out for qualitative and quantification study.
Finally, numerical simulation example illustrates the feasibility of proposed
control method.


title:
Instability of D-dimensional extremally charged Reissner-Nordstrom(-de
  Sitter) black holes: Extrapolation to arbitrary D

abstract:
  In our earlier work (PRL 103 (2009) 161101) it was shown that nonextremal
highly charged Reissner-Nordstrom-de Sitter black holes are gravitationally
unstable in D>6-dimensional space-times. Here, we find accurate threshold
values of the $\Lambda$-term at which the instability of the extremally charged
black holes starts. The larger $D$ is, the smaller is the threshold value of
$\Lambda$. We have shown that the ratio $\rho = r_{h}/r_{cos}$ (where $r_{cos}$
and $r_{h}$ are the cosmological and event horizons) is proportional to
$e^{-(D-4)/2}$ at the onset of instability for D=7,8,...11, implying that the
same law should fulfill for arbitrary D. This is numerical evidence that
extremally charged Reissner-Nordstrom-de Sitter black holes are gravitationally
unstable for D>6, while asymptotically flat extremally charged
Reissner-Nordstrom black holes are stable for all D. The instability is not
connected to the horizon instability discussed recently in the literature, and,
unlike the later one, develops also outside the event horizon, that is, it can
be seen by an external observer. In addition, for the nonextremal case through
fitting of the numerical data we obtained an approximate analytical formula
which relates values of charge and the $\Lambda$-term at the onset of
instability.


title: Do Magnetic Fields Actually Inflate Low-Mass Stars?

abstract:
  Magnetic fields have been hypothesized to inflate the radii of low-mass
stars---defined as less than 0.8 solar masses---in detached eclipsing binaries
(DEBs). We evaluate this hypothesis using the magnetic Dartmouth stellar
evolution code. Results suggest that magnetic suppression of thermal convection
can inflate low-mass stars that possess a radiative core and convective outer
envelope. A scaling relation between X-ray luminosity and surface magnetic flux
indicates that model surface magnetic field strength predictions are consistent
with observations. This supports the notion that magnetic fields may be
inflating these stars. However, magnetic models are unable to reproduce radii
of fully convective stars in DEBs. Instead, we propose that model discrepancies
below the fully convective boundary are related to metallicity.


title: Quantum Tomography From Few Full-Rank Observables

abstract:
  We establish that the PhaseLift algorithm recovers pure states from a
constant number of full-rank observables with high probability.


title:
Analysis of Asymptotic Preserving DG-IMEX Schemes for Linear Kinetic
  Transport Equations in a Diffusive Scaling

abstract:
  In this paper, some theoretical aspects will be addressed for the asymptotic
preserving DG-IMEX schemes recently proposed in [J. Jang, F. Li, J.-M. Qiu and
T. Xiong, submitted, arxiv:1306.0227] for kinetic transport equations under a
diffusive scaling. We will focus on the methods that are based on discontinuous
Galerkin (DG) spatial discretizations with the $P^k$ polynomial space and a
first order IMEX temporal discretization, and apply them to two linear models:
the telegraph equation and the one-group transport equation in slab geometry.
In particular, we will establish uniform numerical stability with respect to
Knudsen number $\varepsilon$ using energy methods, as well as error estimates
for any given $\varepsilon$. When $\varepsilon\rightarrow 0$, a rigorous
asymptotic analysis of the schemes is also obtained. Though the methods and the
analysis are presented for one dimension in space, they can be generalized to
higher dimensions directly.


title:
Bulk evidence for a time reversal symmetry broken superconducting state
  in URu2Si2

abstract:
  URu$_2$Si$_2$ is claimed to be a chiral \emph{d}-wave superconductor with a
$k_z (k_x \pm ik_y)$ time-reversal symmetry broken orbital component for the
Cooper pair wave-function, which contains both nodal points and lines of nodes
\cite{kasahara, kasahara2}. To study the magnetic response of such an
unconventional state through a bulk, thermodynamic probe, we measured the
magnetic torque $\tau$ in very high-quality, well-characterized URu$_2$Si$_2$
single-crystals \cite{altarawneh,altarawneh2} at high magnetic-fields $H$ and
at very low temperatures $T$. The magnetization $M(H) \propto \tau(H) /H$ of
URu$_2$Si$_2$, in its superconducting state and for angles within $15^{\circ}$
from the \emph{ab}-plane, reveals a change in its sign for $H$ approaching
$H_{c2}$: from a clear diamagnetic response dominated by the pinning of
vortices to a state with a smaller but "paramagnetic-like" hysteretic response
which \emph{disappears} at $H_{c2}$, thus implying that it is intrinsically
related to the superconducting state. We argue that this anomalous,
angular-dependent behavior is evidence for a time-reversal symmetry broken
superconducting state in URu$_2$Si$_2$, although not necessarily for the $k_z
(k_x \pm ik_y)$ state.


title:
Classical torus conformal block, N=2* twisted superpotential and the
  accessory parameter of Lame equation

abstract:
  In this work the correspondence between the semiclassical limit of the DOZZ
quantum Liouville theory on the torus and the Nekrasov-Shatashvili limit of the
N=2* (Omega-deformed) U(2) super-Yang-Mills theory is used to propose new
formulae for the accessory parameter of the Lame equation. This quantity is in
particular crucial for solving the problem of uniformization of the
one-punctured torus. The computation of the accessory parameters for torus and
sphere is an open longstanding problem which can however be solved if one
succeeds to derive an expression for the so-called classical Liouville action.
The method of calculation of the latter has been proposed some time ago by
Zamolodchikov brothers. Studying the semiclassical limit of the four-point
function of the quantum Liouville theory on the sphere they have derived the
classical action for the Riemann sphere with four punctures. In the present
work Zamolodchikovs idea is exploited in the case of the Liouville field theory
on the torus. It is found that the Lame accessory parameter is determined by
the classical Liouville action on the one-punctured torus or more concretely by
the torus classical block evaluated on the saddle point intermediate classical
weight. Secondly, as an implication of the aforementioned correspondence it is
obtained that the torus accessory parameter is related to the sum of all
rescaled column lengths of the so-called "critical" Young diagrams extremizing
the instanton "free energy" for the N=2* gauge theory. Finally, it is pointed
out that thanks to the known relation the sum over the "critical" column
lengths can be expressed in terms of a contour integral in which the integrand
is built out of certain special functions.


title: Operations of graphs and unimodality of independence polynomials

abstract:
  Given two graphs $G$ and $H$, assume that $\mathscr{C}=\{C_1,C_2,\ldots,
C_q\}$ is a clique cover of $G$ and $U$ is a subset of $V(H)$. We introduce a
new graph operation called the clique cover product, denoted by
$G^{\mathscr{C}}\star H^U$, as follows: for each clique $C_i\in \mathscr{C}$,
add a copy of the graph $H$ and join every vertex of $C_i$ to every vertex of
$U$. We prove that the independence polynomial of $G^{\mathscr{C}}\star H^U$
$$I(G^{\mathscr{C}}\star H^U;x)=I^q(H;x)I(G;\frac{xI(H-U;x)}{I(H;x)}),$$ which
generalizes some known results on independence polynomials of corona and rooted
products of graphs obtained by Gutman and Rosenfeld, respectively. Based on
this formula, we show that the clique cover product of some special graphs
preserves symmetry, unimodality, log-concavity or reality of zeros of
independence polynomials. As applications we derive several known facts in a
unified manner and solve some unimodality conjectures and problems.


title: Loop-fusion cohomology and transgression

abstract:
  `Loop-fusion cohomology' is defined on the continuous loop space of a
manifold in terms of \vCech cochains satisfying two multiplicative conditions
with respect to the fusion and figure-of-eight products on loops. The main
result is that these cohomology groups, with coefficients in an abelian group,
are isomorphic to those of the manifold and the transgression homomorphism
factors through the isomorphism.


title:
Finiteness of the Tate-Shafarevich Groups for Elliptic Curves over the
  Field of Rational Numbers

abstract:
  Let $E$ be an elliptic curve over $\mathbb{Q}$. Let $\underline{III}(E)$ be a
certain group of equivalence classes of homogeneous spaces of $E$ called its
Tate-Shafarevich group. We show in this paper that this group has finite
cardinality and discuss its role in the Birch and Swinnerton-Dyer Conjecture.
In particular, our result implies the Parity Conjecture, or the Birch and
Swinnerton-Dyer Conjecture modulo 2. It also removes the finiteness condition
of $\underline{III}(E)$ from previous results in the literature of this subject
and makes possible for some computation problems concerning the Strong Birch
and Swinnerton-Dyer Conjecture. In addition, we also give an analogue of the
Hasse-Minkowski Theorem for cubic plane curves.


title: An upper bound on prototype set size for condensed nearest neighbor

abstract:
  The condensed nearest neighbor (CNN) algorithm is a heuristic for reducing
the number of prototypical points stored by a nearest neighbor classifier,
while keeping the classification rule given by the reduced prototypical set
consistent with the full set. I present an upper bound on the number of
prototypical points accumulated by CNN. The bound originates in a bound on the
number of times the decision rule is updated during training in the multiclass
perceptron algorithm, and thus is independent of training set size.


title:
Proof of a tournament partition conjecture and an application to
  1-factors with prescribed cycle lengths

abstract:
  In 1982 Thomassen asked whether there exists an integer f(k,t) such that
every strongly f(k,t)-connected tournament T admits a partition of its vertex
set into t vertex classes V_1,...,V_t such that for all i the subtournament
T[V_i] induced on T by V_i is strongly k-connected. Our main result implies an
affirmative answer to this question. In particular we show that f(k,t) = O(k^7
t^4) suffices. As another application of our main result we give an affirmative
answer to a question of Song as to whether, for any integer t, there exists an
integer h(t) such that every strongly h(t)-connected tournament has a 1-factor
consisting of t vertex-disjoint cycles of prescribed lengths. We show that h(t)
= O(t^5) suffices.


title: Problem Roulette: Studying Introductory Physics in the Cloud

abstract:
  Problem Roulette (PR) is a web-based study service at the University of
Michigan that offers random-within-topic access to a large library of past exam
problems in introductory physics courses. Built on public-private cloud
computing infrastructure, PR served nearly 1000 students during Fall 2012 term,
delivering more than 60,000 problem pages. The service complements that of
commercial publishing houses by offering problems authored by local professors.
We describe the service architecture, including reporting and analytical
capabilities, and present an initial evaluation of the impact of its use. Among
roughly 500 students studying electromagnetism, we find that the 229 students
who worked fifty or more problems over the term outperformed their complement
by 0.40 grade points (on a 4.0 scale). This improvement partly reflects a
selection bias that better students used the service more frequently. Adjusting
for this selection bias by using overall grade point average (GPA) as a
classifier, we find a grade point improvement of 0.22 for regular PR users,
significantly above the random noise level of 0.04. Simply put, students who
worked one or more additional problem per weekday earned nearly a
quarter-letter average grade improvement irrespective of GPA. Student comments
emphasize the importance of randomness in helping them synthesize concepts. The
PR source code is publicly available on the bitbucket repository.


title:
The next generation of $\mu\ -> e \gamma$ and $\mu\ -> 3e$ CLFV search
  experiments

abstract:
  We explore the possibilities for extending the sensitivity of current
searches for the charged lepton flavor violating decays $\mu\ -> e \gamma$ and
$\mu\ -> eee$. A future facility such as Project X at Fermilab could provide a
much more intense stopping $\mu^+$ beam, facilitating more sensitive searches,
but improved detectors will be required as well. Current searches are limited
by accidental and physics backgrounds, as well as by the total number of
stopped muons. One of the limiting factors in current detectors for $\mu\ -> e
\gamma$ searches is the photon energy resolution of the calorimeter. We present
a new fast Monte Carlo simulation of a conceptual design of a new experimental
concept that detects converted $e^+e^-$ pairs from signal photons, taking
advantage of the improved energy resolution of a pair spectrometer based on a
silicon charged particle tracker. We also study a related detector design for a
next generation $\mu\to eee$ search experiment.