title: Solar sources of the geoeffective events in September 2011

abstract:
  We investigate the geoeffective events happened from 8 to 20 Sept 2011,
analysing the most plausible solar sources of these events, where coronal mass
ejections and coronal holes play a fundamental role. The physical properties of
the coronal holes, such as area and magnetic field, are studied through the
Solar Dynamics Observatory instruments: AIA 193 {\AA} images and HMI
longitudinal magnetograms. The active regions which are the origin of the
coronal mass ejections are analysed in AIA and SoHO-LASCO data.


title: A cellular approach to the Hecke-Clifford superalgebra

abstract:
  The Hecke-Clifford superalgebra is a super-analogue of the Iwahori-Hecke
algebra of type A. The classification of its simple modules is done by Brundan,
Kleshchev and Tsuchioka using a method of categorification of affine Lie
algebras. In this paper, we introduce another way to produce its simple modules
with a generalized theory of cellular algebras which is originally developed by
Graham and Lehrer. In our construction the key is that there is a right action
of the Clifford superalgebra on the super-analogue of the Specht module. With
the help of the notion of the Morita context, a simple module of the
Hecke-Clifford superalgebra is made from that of the Clifford superalgebra.


title: Wireless Scheduling Algorithms in Complex Environments

abstract:
  Efficient spectrum use in wireless sensor networks through spatial reuse
requires effective models of packet reception at the physical layer in the
presence of interference. Despite recent progress in analytic and simulations
research into worst-case behavior from interference effects, these efforts
generally assume geometric path loss and isotropic transmission, assumptions
which have not been borne out in experiments.
  Our paper aims to provide a methodology for grounding theoretical results
into wireless interference in experimental reality. We develop a new framework
for wireless algorithms in which distance-based path loss is replaced by an
arbitrary gain matrix, typically obtained by measurements of received signal
strength (RSS). Gain matrices allow for the modeling of complex environments,
e.g., with obstacles and walls. We experimentally evaluate the framework in two
indoors testbeds with 20 and 60 motes, and confirm superior predictive
performance in packet reception rate for a gain matrix model over a geometric
distance-based model.
  At the heart of our approach is a new parameter $\zeta$ called metricity
which indicates how close the gain matrix is to a distance metric, effectively
measuring the complexity of the environment. A powerful theoretical feature of
this parameter is that all known SINR scheduling algorithms that work in
general metric spaces carry over to arbitrary gain matrices and achieve
equivalent performance guarantees in terms of $\zeta$ as previously obtained in
terms of the path loss constant. Our experiments confirm the sensitivity of
$\zeta$ to the nature of the environment. Finally, we show analytically and
empirically how multiple channels can be leveraged to improve metricity and
thereby performance. We believe our contributions will facilitate experimental
validation for recent advances in algorithms for physical wireless interference
models.


title:
Kinematic Properties of Slow ICMEs and an Interpretation of a Modified
  Drag Equation for Fast and Moderate ICMEs

abstract:
  We report kinematic properties of slow interplanetary coronal mass ejections
(ICMEs) identified by SOHO/LASCO, interplanetary scintillation, and in-situ
observations, and propose a modified equation for the ICME motion. We identify
seven ICMEs between 2010 and 2011, and examine them with 39 events reported in
our previous work. We examine 15 fast (V_SOHO - V_bg > 500 km/s), 25 moderate
(0 km/s <= V_SOHO - V_bg <= 500 km/s), and 6 slow (V_SOHO - V_bg < 0 km/s)
ICMEs, where V_SOHO and V_bg are the initial speed of ICMEs and the speed of
the background solar wind, respectively. For slow ICMEs, we found the following
results: i) They accelerate toward the speed of the background solar wind
during their propagation, and reach their final speed by 0.34 (+-) 0.03 AU. ii)
The acceleration ends when they reach 479 (+-) 126 km/s; this is close to the
typical speed of the solar wind during the period of this study. iii) When k_1
and k_2 are assumed to be constants, a quadratic equation for the acceleration
a = -k_2(V - V_bg)|V - V_bg| is more appropriate than a linear one a = -k_1(V -
V_bg), where V is the propagation speed of ICMEs, while the latter gives a
smaller chi-square value than the former. For the motion of the fast and
moderate ICMEs, we found a modified drag equation. From the viewpoint of fluid
dynamics, we interpret this equation as indicating that ICMEs with 0 km/s <= V
- V_bg <= 2300 km/s are controlled mainly by the hydrodynamic Stokes drag
force, while the aerodynamic drag force is a predominant factor for the
propagation of ICME with V - V_bg > 2300 km/s.


title: The puzzle conjecture for the cohomology of two-step flag manifolds

abstract:
  We prove a conjecture of Knutson asserting that the Schubert structure
constants of the cohomology ring of a two-step flag variety are equal to the
number of puzzles with specified border labels that can be created using a list
of eight puzzle pieces. As a consequence, we obtain a puzzle formula for the
Gromov-Witten invariants defining the small quantum cohomology ring of a
Grassmann variety of type A. The proof of the conjecture proceeds by showing
that the puzzle formula defines an associative product on the cohomology ring
of the two-step flag variety. It is based on an explicit bijection of gashed
puzzles that is analogous to the jeu de taquin algorithm but more complicated.


title:
Comparison results for semilinear elliptic equations using a new
  symmetrization method

abstract:
  In this paper, we prove some pointwise comparison results between the
solutions of some second-order semilinear elliptic equations in a domain
$\Omega$ of $\R^n$ and the solutions of some radially symmetric equations in
the equimeasurable ball $\Omega^*$. The coefficients of the symmetrized
equations in~$\Omega^*$ satisfy similar constraints as the original ones
in~$\Omega$. We consider both the case of equations with linear growth in the
gradient and the case of equations with at most quadratic growth in the
gradient. Lastly, we show some improved quantified comparisons when the
original domain is not a ball. The method is based on a symmetrization of the
second-order terms.


title: Sharp interface limit for two components Bose-Einstein condensates

abstract:
  We study a double Cahn-Hilliard type functional related to the
Gross-Pitaevskii energy of two-components Bose-Einstein condensates. In the
case of large but same order intercomponent and intracomponent coupling
strengths, we prove $\Gamma$-convergence to a perimeter minimisation functional
with an inhomogeneous surface tension. We study the asymptotic behavior of the
surface tension as the ratio between the intercomponent and intracomponent
coupling strengths becomes very small or very large. We obtain as a
consequence, symmetry breaking of the minimisers for the harmonic potential
when this radio is sufficiently large.


title: Variability in Ultra-luminous X-ray Sources

abstract:
  Many upcoming surveys, particularly in the radio and optical domains, are
designed to probe either the temporal and/or the spatial variability of a range
of astronomical objects. In the light of these high resolution surveys, we
review the subject of ultra-luminous X-ray (ULX) sources, which are thought to
be accreting black holes for the most part. We also discuss the sub-class of
ULXs known as the hyper-luminous X-ray sources, which may be accreting
intermediate mass black holes. We focus on some of the open questions that will
be addressed with the new facilities, such as the mass of the black hole in
ULXs, their temporal variability and the nature of the state changes, their
surrounding nebulae and the nature of the region in which ULXs reside.


title: Diluted Mean-Field Spin-Glass Models at Criticality

abstract:
  We present a method derived by cavity arguments to compute the spin-glass and
higher-order susceptibilities in diluted mean-field spin-glass models. The
divergence of the spin-glass susceptibility is associated to the existence of a
non-zero solution of a homogeneous linear integral equation. Higher order
susceptibilities, relevant for critical dynamics through the parameter exponent
$\lambda$, can be expressed at criticality as integrals involving the critical
eigenvector. The numerical evaluation of the corresponding analytic expressions
is discussed. The method is illustrated in the context of the de
Almeida-Thouless line for a spin-glass on a Bethe lattice but can be
generalized straightforwardly to more complex situations.


title: 2p-Commutator on differential operators of order p

abstract:
  We show that a space of one variable differential operators of order $p$
admits non-trivial $2p$-commutator and the number $2p$ here can not be
improved.


title: Random Telegraph Signal in a Metallic Double-Dot System

abstract:
  In this work, we investigate the dynamics of a single electron surface trap,
embedded in a self-assembly metallic double-dot system. The charging and
discharging of the trap by a single electron is manifested as a random
telegraph signal of the current through the double-dot device. We find that we
can control the duration time that an electron resides in the trap through the
current that flows in the device, between fractions of a second to more than an
hour. We suggest that the observed switching is the electrical manifestation of
the optical blinking phenomenon, commonly observed in semiconductor quantum
dots.


title:
Looking at Vector Space and Language Models for IR using Density
  Matrices

abstract:
  In this work, we conduct a joint analysis of both Vector Space and Language
Models for IR using the mathematical framework of Quantum Theory. We shed light
on how both models allocate the space of density matrices. A density matrix is
shown to be a general representational tool capable of leveraging capabilities
of both VSM and LM representations thus paving the way for a new generation of
retrieval models. We analyze the possible implications suggested by our
findings.


title:
The Very Bright and Nearby GRB 130427A: The Extra Hard Spectral
  Component and Implications for Very High-energy Gamma-ray Observations of
  Gamma-ray Bursts

abstract:
  The extended high-energy gamma-ray (>100 MeV) emission occurring after the
prompt gamma-ray bursts (GRBs) is usually characterized by a single power-law
spectrum, which has been explained as the afterglow synchrotron radiation. We
report on the Fermi Large Area Telescope (LAT) observations of the >100 MeV
emission from the very bright and nearby GRB 130427A, up to ~100 GeV. By
performing time-resolved spectral fits of GRB 130427A, we found a strong
evidence of an extra hard spectral component above a few GeV that exists in the
extended high-energy emission of this GRB. This extra spectral component may
represent the first clear evidence of the long sought-after afterglow inverse
Compton emission. Prospects for observations at the very high-energy
gamma-rays, i.e., above 100 GeV, are described.


title: Algorithmic Randomness for Infinite Time Register Machines

abstract:
  A concept of randomness for infinite time register machines (ITRMs),
resembling Martin-L\"of-randomness, is defined and studied. In particular, we
show that for this notion of randomness, computability from mutually random
reals implies computability and that an analogue of van Lambalgen's theorem
holds.


title: Exploring the Phase Structure and Thermodynamics of QCD

abstract:
  We put forward a Polyakov-loop extended quark meson model, where matter as
well as glue fluctuations are taken into account, cf. [1]. The latter are
included via a Polyakov-loop potential. Usually such a glue potential is based
on Yang-Mills lattice data only. We show that a parametrisation of unquenching
effects as proposed in [2], together with the inclusion of fluctuations via the
functional renormalisation group [3,4], accounts for the relevant dynamics.
This is demonstrated by a comparison of order parameters and thermodynamic
observables to recent lattice results at vanishing chemical potential, where we
find very good agreement.


title:
Statistical Topology of Three-Dimensional Poisson-Voronoi Cells and Cell
  Boundary Networks

abstract:
  Voronoi tessellations of Poisson point processes are widely used for modeling
many types of physical and biological systems. In this paper, we analyze
simulated Poisson-Voronoi structures containing a total of 250,000,000 cells to
provide topological and geometrical statistics of this important class of
networks. We also report correlations between some of these topological and
geometrical measures. Using these results, we are able to corroborate several
conjectures regarding the properties of three-dimensional Poisson-Voronoi
networks and refute others. In many cases, we provide accurate fits to these
data to aid further analysis. We also demonstrate that topological measures
represent powerful tools for describing cellular networks and for
distinguishing among different types of networks.


title:
Nature of $\gamma$-deformation in Ge and Se nuclei and the triaxial
  projected shell model description

abstract:
  Recent experimental data have demonstrated that $^{76}$Ge may be a rare
example of a nucleus exhibiting rigid $\gamma$-deformation in the low-spin
regime. In the present work, the experimental analysis is supported by
microscopic calculations using the multi-quasiparticle triaxial projected shell
model (TPSM) approach. It is shown that to best describe the data of both yrast
and $\gamma$-vibrational bands in $^{76}$Ge, a rigid-triaxial deformation
parameter $\gamma\approx 30^\circ$ is required. TPSM calculations are discussed
in conjunction with the experimental observations and also with the published
results from the spherical shell model. The occurrence of a $\gamma\gamma$-band
in $^{76}$Ge is predicted with the bandhead at an excitation energy of $ \sim$
2.5 MeV. We have also performed TPSM study for the neighboring Ge- and
Se-isotopes and the distinct $\gamma$-soft feature in these nuclei is shown to
result from configuration mixing of the ground-state with multi-quasiparticle
states.


title:
On the orbital stability of Gaussian solitary waves in the log-KdV
  equation

abstract:
  We consider the logarithmic Korteweg-de Vries (log-KdV) equation, which
models solitary waves in anharmonic chains with Hertzian interaction forces. By
using an approximating sequence of global solutions of the regularized
generalized KdV equation in $H^1(\mathbb{R})$ with conserved $L^2$ norm and
energy, we construct a weak global solution of the log-KdV equation in a subset
of $H^1(\mathbb{R})$. This construction yields conditional orbital stability of
Gaussian solitary waves of the log-KdV equation, provided uniqueness and
continuous dependence of the constructed solution holds.
  Furthermore, we study the linearized log-KdV equation at the Gaussian
solitary wave and prove that the associated linearized operator has a purely
discrete spectrum consisting of simple purely imaginary eigenvalues in addition
to the double zero eigenvalue. The eigenfunctions, however, do not decay like
Gaussian functions but have algebraic decay. Nevertheless, using numerical
approximations, we show that the Gaussian initial data do not spread out and
preserve their spatial Gaussian decay in the time evolution of the linearized
log-KdV equation.


title: Variations of Solar Non-axisymmetric Activity

abstract:
  The temporal behaviour of solar active longitudes has been examined by using
two sunspot catalogues, the Greenwich Photoheliographic Results (GPR) and the
Debrecen Photoheliographic Data (DPD). The time-longitude diagrams of the
activity distribution reveal the preferred longitudinal zones and their
migration with respect to the Carrington frame. The migration paths outline a
set of patterns in which the activity zone has alternating prograde/retrograde
angular velocities with respect to the Carrington rotation rate. The time
profiles of these variations can be described by a set of successive parabolae.
Two similar migration paths have been selected from these datasets, one
northern path during cycles 21 - 22 and one southern path during cycles 13 -
14, for closer examination and comparison of their dynamical behaviours. The
rates of sunspot emergence exhibited in both migration paths similar
periodicities, close to 1.3 years. This behaviour may imply that the active
longitude is connected to the bottom of convection zone.


title:
Heat Kernel Asymptotic Expansion on Unbounded Domains with Polynomially
  Confining Potentials

abstract:
  In this paper we analyze the small-t asymptotic expansion of the trace of the
heat kernel associated with a Laplace operator endowed with a spherically
symmetric polynomially confining potential on the unbounded, d-dimensional
Euclidean space. To conduct this study, the trace of the heat kernel is
expressed in terms of its partially resummed form which is then represented as
a Mellin-Barnes integral. A suitable contour deformation then provides, through
the use of Cauchy's residue theorem, closed formulas for the coefficients of
the asymptotic expansion. The general expression for the asymptotic expansion,
valid for any dimension and any polynomially confining potential, is then
specialized to two particular cases: the general quartic and sestic oscillator
potentials.


title: A New Topological "Twist" to BR Scaling

abstract:
  When vector mesons are considered on the same footing as pions as suggested
by hidden local symmetry, the property of the nuclear tensor forces is strongly
controlled by the behavior of the vector mesons in dense medium. This led to BR
scaling in 1991. When baryons as skyrmions are put on crystal, there can be a
phase transition from skyrmions to half-skyrmions at a density above that of
normal nuclear matter. This topology change can induce fundamental changes to
the parameters in hidden local symmetric Lagrangian, hence BR scaling, and
brings a drastic modification to the structure of nuclear forces, in
particulrar, the tensor forces. This can have far-reaching consequences on the
EoS of compact-star matter and the structure of neutron-rich nuclei.


title: Content Based Image Indexing and Retrieval

abstract:
  In this paper, we present the efficient content based image retrieval systems
which employ the color, texture and shape information of images to facilitate
the retrieval process. For efficient feature extraction, we extract the color,
texture and shape feature of images automatically using edge detection which is
widely used in signal processing and image compression. For facilitated the
speedy retrieval we are implements the antipole-tree algorithm for indexing the
images.


title:
Dynamics of symmetry breaking during quantum real-time evolution in a
  minimal model system

abstract:
  One necessary criterion for the thermalization of a nonequilibrium quantum
many-particle system is ergodicity. It is, however, not sufficient in case
where the asymptotic long-time state lies in a symmetry-broken phase but the
initial state of nonequilibrium time evolution is fully symmetric with respect
to this symmetry. In equilibrium one particular symmetry-broken state is chosen
due to the presence of an infinitesimal symmetry-breaking perturbation. We
study the analogous scenario from a dynamical point of view: Can an
infinitesimal symmetry-breaking perturbation be sufficient for the system to
establish a nonvanishing order during quantum real-time evolution? We study
this question analytically for a minimal model system that can be associated
with symmetry breaking, the ferromagnetic Kondo model. We show that after a
quantum quench from a completely symmetric state the system is able to break
its symmetry dynamically and discuss how these features can be observed
experimentally.


title:
Enhancement of the magnetocaloric effect driven by changes in the
  crystal structure of Al doped GGG, Gd3Ga5-xAlxO12 (0 < x < 5)

abstract:
  The Gd3Ga5-xAlxO12 (0 < x < 5) solid solution has been prepared using ceramic
synthesis routes and the structural and magnetic properties investigated using
X-ray diffraction, magnetic susceptibility, chi, and isothermal magnetisation,
M(H), measurements. Our results indicate a contraction of the unit cell and
more significant antiferromagnetic interactions as x increases. Despite the
decrease in the magnetic polarisation on application of a field and the
corresponding decrease in the change in the magnetic entropy we find that
Gd3Al5O12 has a significantly higher observed (17%) and theoretical (14%) DS
per unit mass than Gd3Ga5O12. Per unit volume the theoretical increase in DS
(7%) is offset by the increased antiferromagnetic interactions in Gd3Al5O12.
The differences in DS are driven by a decrease in both the mass and density as
Al ions replace Ga ions. These results highlight the importance of changes to
the crystal structure when considering materials for solid state magnetic
cooling.


title:
Perfect state transfer on distance-regular graphs and association
  schemes

abstract:
  We consider the representation of a continuous-time quantum walk in a graph
$X$ by the matrix $\exp(itA(X))$. We provide necessary and sufficient criteria
for distance-regular graphs and, more generally, for graphs in association
schemes to have perfect state transfer. Using these conditions, we provide
several new examples of perfect state transfer in simple graphs.


title:
Gravitational behavior of an effective topological field theory in a
  gravitational instanton background

abstract:
  Effective topological field theories describe the properties of Dirac
fermions in the low-energy regime. In this work, we introduce a new emergent
gravity model by considering Dirac fermions invariant under local de Sitter
transformations in four-dimensional open manifolds. In the context of Cartan
geometry, fermions couple to spacetime through a $Spin(5)$ Cartan connection
that can be decomposed in spin connection and tetrads. In presence of a
gravitational instanton background, we show that the corresponding effective
topological field theory becomes a dynamical gravitational theory with a
positive cosmological constant and Barbero-Immirzi parameter. At classical
level and in absence of matter, this theory is compatible with general
relativity.


title:
Any realistic theory must be computationally realistic: a response to N.
  Gisin's definition of a Realistic Physics Theory

abstract:
  It is argued that the recent definition of a realistic physics theory by N.
Gisin cannot be considered comprehensive unless it is supplemented with
requirement that any realistic theory must be computationally realistic as
well.


title: Testing the Perey Effect

abstract:
  Background: The effects of non-local potentials have historically been
approximately included by applying a correction factor to the solution of the
corresponding equation for the local equivalent interaction. This is usually
referred to as the Perey correction factor. Purpose: In this work we
investigate the validity of the Perey correction factor for single-channel
bound and scattering states, as well as in transfer (p,d) cross sections.
Method: We solve the scattering and bound state equations for non-local
interactions of the Perey-Buck type, through an iterative method. Using the
distorted wave Born approximation, we construct the T-matrix for (p,d) on 17O,
41Ca, 49Ca, 127Sn, 133Sn, and 209Pb at 20 and 50 MeV. Results: We found that
for bound states, the Perey corrected wave function resulting from the local
equation agreed well with that from the non-local equation in the interior
region, but discrepancies were found in the surface and peripheral regions.
Overall, the Perey correction factor was adequate for scattering states, with
the exception of a few partial waves corresponding to the grazing impact
parameters. These differences proved to be important for transfer reactions.
Conclusions: The Perey correction factor does offer an improvement over taking
a direct local equivalent solution. However, if the desired accuracy is to be
better than 10%, the exact solution of the non-local equation should be
pursued.


title:
Reconstructing transmission trees for communicable diseases using
  densely sampled genetic data

abstract:
  Whole genome sequencing of pathogens from multiple hosts in an epidemic
offers the potential to investigate who infected whom with unparalleled
resolution, potentially yielding important insights into disease dynamics and
the impact of control measures. We considered disease outbreaks in a setting
with dense genomic sampling, and formulated stochastic epidemic models to
investigate person-to-person transmission, based on observed genomic and
epidemiological data. We constructed models in which the genetic distance
between sampled genotypes depends on the epidemiological relationship between
the hosts. A data augmented Markov chain Monte Carlo algorithm was used to
sample over the transmission trees, providing a posterior probability for any
given transmission route. We investigated the predictive performance of our
methodology using simulated data, demonstrating high sensitivity and
specificity, particularly for rapidly mutating pathogens with low
transmissibility. We then analyzed data collected during an outbreak of
methicillin-resistant Staphylococcus aureus in a hospital, identifying probable
transmission routes and estimating epidemiological parameters. Our approach
overcomes limitations of previous methods, providing a framework with the
flexibility to allow for unobserved infection times, multiple independent
introductions of the pathogen, and within-host genetic diversity, as well as
allowing forward simulation.


title: A recursion for counts of real curves in CP^{2n-1}: another proof

abstract:
  In a recent paper, we obtained a WDVV-type relation for real genus 0
Gromov-Witten invariants with conjugate pairs of insertions; it specializes to
a complete recursion in the case of odd-dimensional projective spaces. This
note provides another, more complex-geometric, proof of the latter. The main
part of this approach readily extends to real symplectic manifolds with empty
real locus, but not to the general case.


title: Ensemble renormalization group for the random field hierarchical model

abstract:
  The Renormalization Group (RG) methods are still far from being completely
understood in quenched disordered systems. In order to gain insight into the
nature of the phase transition of these systems, it is common to investigate
simple models. In this work we study a real-space RG transformation on the
Dyson hierarchical lattice with a random field, which led to a reconstruction
of the RG flow and to an evaluation of the critical exponents of the model at T
= 0. We show that this method gives very accurate estimations of the critical
exponents, by comparing our results with the ones obtained by some of us using
an independent method.


title:
Speeding up SOR Solvers for Constraint-based GUIs with a Warm-Start
  Strategy

abstract:
  Many computer programs have graphical user interfaces (GUIs), which need good
layout to make efficient use of the available screen real estate. Most GUIs do
not have a fixed layout, but are resizable and able to adapt themselves.
Constraints are a powerful tool for specifying adaptable GUI layouts: they are
used to specify a layout in a general form, and a constraint solver is used to
find a satisfying concrete layout, e.g.\ for a specific GUI size. The
constraint solver has to calculate a new layout every time a GUI is resized or
changed, so it needs to be efficient to ensure a good user experience. One
approach for constraint solvers is based on the Gauss-Seidel algorithm and
successive over-relaxation (SOR).
  Our observation is that a solution after resizing or changing is similar in
structure to a previous solution. Thus, our hypothesis is that we can increase
the computational performance of an SOR-based constraint solver if we reuse the
solution of a previous layout to warm-start the solving of a new layout. In
this paper we report on experiments to test this hypothesis experimentally for
three common use cases: big-step resizing, small-step resizing and constraint
change. In our experiments, we measured the solving time for randomly generated
GUI layout specifications of various sizes. For all three cases we found that
the performance is improved if an existing solution is used as a starting
solution for a new layout.


title: A Solution of Degree Constrained Spanning Tree Using Hybrid GA

abstract:
  In real life, it is always an urge to reach our goal in minimum effort i.e.,
it should have a minimum constrained path. The path may be shortest route in
practical life, either physical or electronic medium. The scenario is to
represents the ambiance as a graph and to find a spanning tree with custom
design criteria. Here, we have chosen a minimum degree spanning tree, which can
be generated in real time with minimum turnaround time. The problem is
NP-complete in nature [1, 2]. The solution approach, in general, is
approximate. We have used a heuristic approach, namely hybrid genetic algorithm
(GA), with motivated criteria of encoded data structures of graph. We compare
the experimental result with the existing approximate algorithm and the result
is so encouraging that we are interested to use it in our future applications.


title: Greedy Strategies for Convex Optimization

abstract:
  We investigate two greedy strategies for finding an approximation to the
minimum of a convex function $E$ defined on a Hilbert space $H$. We prove
convergence rates for these algorithms under suitable conditions on the
objective function $E$. These conditions involve the behavior of the modulus of
smoothness and the modulus of uniform convexity of $E$.


title: Mobility-Dependent Selection of Competing Strategy Associations

abstract:
  Standard models of population dynamics focus on the the interaction,
survival, and extinction of the competing species individually. Real ecological
systems, however, are characterized by an abundance of species (or strategies,
in the terminology of evolutionary-game theory) that form intricate, complex
interaction networks. The description of the ensuing dynamics may be aided by
studying associations of certain strategies rather than individual ones. Here
we show how such a higher-level description can bear fruitful insight.
Motivated from different strains of colicinogenic Escherichia coli bacteria, we
investigate a four-strategy system which contains a three-strategy cycle and a
neutral alliance of two strategies. We find that the stochastic, spatial model
exhibits a mobility-dependent selection of either the three-strategy cycle or
of the neutral pair. We analyze this intriguing phenomenon numerically and
analytically.


title: Quantum spread spectrum multiple access

abstract:
  We describe a quantum multiple access scheme that can take separate single
photon channels and combine them in the same path. We propose an add-drop
multiplexer that can insert or extract a single photon into an optical fibre
carrying the qubits of all the other users. The system follows the principle of
code division multiple access, a spread spectrum technique widely used in
cellular networks.


title:
An efficient algorithm for the calculation of reserves for non-unit
  linked life policies

abstract:
  The underlying stochastic nature of the requirements for the Solvency II
regulations has introduced significant challenges if the required calculations
are to be performed correctly, without resorting to excessive approximations,
within practical timescales. It is generally acknowledged by practising
actuaries within UK life offices that it is currently impossible to correctly
fulfil the requirements imposed by Solvency II using existing computational
techniques based on commercially available valuation packages. Our work has
already shown that it is possible to perform profitability calculations at a
far higher rate than is achievable using commercial packages. One of the key
factors in achieving these gains is to calculate reserves using recurrence
relations that scale linearly with the number of time steps. Here, we present a
general vector recurrence relation which can be used for a wide range of
non-unit linked policies that are covered by Solvency II; such contracts
include annuities, term assurances, and endowments. Our results suggest that by
using an optimised parallel implementation of this algorithm, on an affordable
hardware platform, it is possible to perform the `brute force' approach to
demonstrating solvency in a realistic timescale (of the order of a few hours).


title: Jet Quenching and Correlations

abstract:
  This article reviews recent advances in our understanding of the experimental
aspects of jet-quenching and correlations in relativistic heavy-ion collisions
at RHIC and LHC. Emphasis is put on correlation measurements, namely jet-like
correlations with anisotropic flow subtraction in heavy-ion collisions and
long-range pseudorapidity correlations in small systems. Future path on
correlation studies is envisioned which may elucidate jet-medium interactions
and the properties of the hot dense medium in QCD.


title:
A Twisted ${\mathcal C}^{\star}$-algebra formulation of Quantum
  Cosmology with application to the Bianchi I model

abstract:
  A twisted ${\mathcal C}^\star $- algebra of the extended (noncommutative)
Heisenberg-Weyl group has been constructed which takes into account the
Uncertainty Principle for coordinates in the Planck length regime. This general
construction is then used to generate an appropriate Hilbert space and
observables for the noncommutative theory which, when applied to the Bianchi I
Cosmology, leads to a new set of equations that describe the quantum evolution
of the universe. We find that this formulation matches theories based on a
reticular Heisenberg-Weyl algebra in the bouncing and expanding regions of a
collapsing Bianchi universe. There is, however, an additional effect introduced
by the dynamics generated by the noncommutativity. This is an oscillation in
the spectrum of the volume operator of the universe, within the bouncing region
of the commutative theories. We show that this effect is generic and produced
by the noncommutative momentum exchange between the degrees of freedom in the
cosmology. We give asymptotic and numerical solutions which show the above
mentioned effects of the noncommutativity.


title:
Generalized Proportional Allocation Mechanism Design for Unicast Service
  on the Internet

abstract:
  In this report we construct two mechanisms that fully implement social
welfare maximising allocation in Nash equilibria for the case of a single
infinitely divisible good subject to multiple inequality constraints. The first
mechanism achieves weak budget balance, while the second is an extension of the
first, and achieves strong budget balance. One important application of this
mechanism is unicast service on the Internet where a network operator wishes to
allocate rates among strategic users in such a way that maximise overall user
satisfaction while respecting capacity constraints on every link in the
network. The emphasis of this work is on full implementation, which means that
all Nash equilibria of the induced game result in the optimal allocations of
the centralized allocation problem.


title:
Liquid crystal hyperbolic metamaterial for wide-angle negative-positive
  refraction and reflection

abstract:
  We show that nanosphere dispersed liquid crystal (NDLC) metamaterial can be
characterized in near IR spectral region as an indefinite medium whose real
parts of effective ordinary and extraordinary permittivities are opposite in
signs. Based on this fact we design a novel electrooptic effect: external
electric field driven switch between normal refraction, negative refraction and
reflection of TM incident electromagnetic wave from the boundary vacuum/NDLC. A
detailed analysis of its functionality is given based on effective medium
theory combined with a study of negative refraction in anisotropic
metamaterials, and Finite Elements simulations.


title:
Heat Conduction, and the Lack Thereof, in Time-Reversible Dynamical
  Systems: Generalized Nos\'e-Hoover Oscillators with a Temperature Gradient

abstract:
  We use nonequilibrium molecular dynamics to analyze and illustrate the
qualitative differences between the one-thermostat and two-thermostat versions
of equilibrium and nonequilibrium (heat-conducting) harmonic oscillators.
Conservative nonconducting regions can coexist with dissipative heat conducting
regions in phase space with exactly the same imposed temperature field.

categories: cond-mat.stat-mech nlin.CD physics.class-ph physics.comp-ph


title: Approximating Large Frequency Moments with $O(n^{1-2/k})$ Bits

abstract:
  In this paper we consider the problem of approximating frequency moments in
the streaming model. Given a stream $D = \{p_1,p_2,\dots,p_m\}$ of numbers from
$\{1,\dots, n\}$, a frequency of $i$ is defined as $f_i = |\{j: p_j = i\}|$.
The $k$-th \emph{frequency moment} of $D$ is defined as $F_k = \sum_{i=1}^n
f_i^k$.
  In this paper we give an upper bound on the space required to find a $k$-th
frequency moment of $O(n^{1-2/k})$ bits that matches, up to a constant factor,
the lower bound of Woodruff and Zhang (STOC 12) for constant $\epsilon$ and
constant $k$. Our algorithm makes a single pass over the stream and works for
any constant $k > 3$.


title:
Magnetic fields in fully convective M-dwarfs: oscillatory dynamos vs
  bistability

abstract:
  M-dwarfs demonstrate two types of activity: 1) strong (kilogauss) almost
axisymmetric poloidal magnetic fields; and 2) considerably weaker
nonaxisymmetric fields, sometimes including a substantial toroidal component.
Dynamo bistability has been proposed as an explanation. However it is not
straightforward to obtain such a bistability in dynamo models. On the other
hand, the solar magnetic dipole at times of magnetic field inversion becomes
transverse to the rotation axis, while the magnetic field becomes weaker at
times far from that of inversion. Thus the
  Sun resembles a star with the second type of activity. We suggest that
M-dwarfs can have magnetic cycles, and that M-dwarfs with the second type of
activity can just be stars observed at times of magnetic field inversion. Then
the relative number of M-dwarfs with the second type of activity can be used in
the framework of this model to determine parameters of stellar convection near
the surface.


title: Some properties of analytic difference fields

abstract:
  We prove field quantifier elimination for valued fields endowed with both an
analytic structure and an automorphism that are $\sigma$-Henselian. From this
result we can deduce various Ax-Kochen-Ersov type results with respect to
completeness and the NIP property. The main example we are interested in is the
field of Witt vectors on the algebraic closure of $\mathbb{F}_{p}$ endowed with
its natural analytic structure and the lifting of the Frobenius. It turns out
we can give a (reasonable) axiomatization of its first order theory and that
this theory is NIP.


title:
G-Bean: an ontology-graph based web tool for biomedical literature
  retrieval

abstract:
  Currently, most people use PubMed to search the MEDLINE database, an
important bibliographical information source for life science and biomedical
information. However, PubMed has some drawbacks that make it difficult to find
relevant publications pertaining to users' individual intentions, especially
for non-expert users. To ameliorate the disadvantages of PubMed, we developed
G-Bean, a graph based biomedical search engine, to search biomedical articles
in MEDLINE database more efficiently.G-Bean addresses PubMed's limitations with
three innovations: parallel document index creation,ontology-graph based query
expansion, and retrieval and re-ranking of documents based on user's search
intention.Performance evaluation with 106 OHSUMED benchmark queries shows that
G-Bean returns more relevant results than PubMed does when using these queries
to search the MEDLINE database. PubMed could not even return any search result
for some OHSUMED queries because it failed to form the appropriate Boolean
query statement automatically from the natural language query strings. G-Bean
is available at http://bioinformatics.clemson.edu/G-Bean/index.php.G-Bean
addresses PubMed's limitations with ontology-graph based query expansion,
automatic document indexing, and user search intention discovery. It shows
significant advantages in finding relevant articles from the MEDLINE database
to meet the information need of the user.


title:
Breaking the Hierarchy: Distributed Control & Economic Optimality in
  Microgrids

abstract:
  Modeled after the hierarchical control architecture of power transmission
systems, a layering of primary, secondary, and tertiary control has become the
standard operation paradigm for islanded microgrids. Despite this superficial
similarity, the control objectives in microgrids across these three layers are
varied and ambitious, and they must be achieved while allowing for robust
plug-and-play operation and maximal flexibility, without hierarchical decision
making and time-scale separations. In this work, we explore control strategies
for these three layers and illuminate some possibly-unexpected connections and
dependencies among them. Building from a first-principle analysis of
decentralized primary droop control, we study centralized, decentralized, and
distributed architectures for secondary frequency regulation. We find that
averaging-based distributed controllers using communication among the
generation units offer the best combination of flexibility and performance. We
further leverage these results to study constrained AC economic dispatch in a
tertiary control layer. Surprisingly, we show that the minimizers of the
economic dispatch problem are in one-to-one correspondence with the set of
steady-states reachable by droop control. In other words, the adoption of droop
control is necessary and sufficient to achieve economic optimization. This
equivalence results in simple guidelines to select the droop coefficients,
which include the known criteria for power sharing. We illustrate the
performance and robustness of our designs through simulations.


title:
The clustering of galaxies in the SDSS-III Baryon Oscillation
  Spectroscopic Survey: galaxy clustering measurements in the low redshift
  sample of Data Release 11

abstract:
  We present the distance measurement to z = 0.32 using the 11th data release
of the Sloan Digital Sky Survey-III Baryon Acoustic Oscillation Survey (BOSS).
We use 313,780 galaxies of the low-redshift (LOWZ) sample over 7,341
square-degrees to compute $D_V = (1264 \pm 25)(r_d/r_{d,fid})$ - a sub 2%
measurement - using the baryon acoustic feature measured in the galaxy
two-point correlation function and power-spectrum. We compare our results to
those obtained in DR10. We study observational systematics in the LOWZ sample
and quantify potential effects due to photometric offsets between the northern
and southern Galactic caps. We find the sample to be robust to all systematic
effects found to impact on the targeting of higher-redshift BOSS galaxies, and
that the observed north-south tensions can be explained by either limitations
in photometric calibration or by sample variance, and have no impact on our
final result. Our measurement, combined with the baryonic acoustic scale at z =
0.57, is used in Anderson et al. (2013a) to constrain cosmological parameters.


title: Concordance Cosmology with Particle Creation

abstract:
  A constant-rate creation of dark particles in the late-time FLRW spacetime
provides a cosmological model in accordance with precise observational tests.
The matter creation backreaction implies in this context a vacuum energy
density scaling linearly with the Hubble parameter, which is consistent with
the vacuum expectation value of the QCD condensate in a low-energy expanding
spacetime. Both the cosmological constant and coincidence problems are
alleviated in this scenario. We discuss the cosmological model that arises in
this context and present a joint analysis of observations of the first acoustic
peak in the cosmic microwave background (CMB) anisotropy spectrum, the Hubble
diagram for supernovas of type Ia (SNIa), the distance scale of baryonic
acoustic oscillations (BAO) and the distribution of large scale structures
(LSS). We show that a good concordance is obtained, albeit with a higher value
of the present matter abundance than in the standard model.


title: Adaptive Replication in Distributed Content Delivery Networks

abstract:
  We address the problem of content replication in large distributed content
delivery networks, composed of a data center assisted by many small servers
with limited capabilities and located at the edge of the network. The objective
is to optimize the placement of contents on the servers to offload as much as
possible the data center. We model the system constituted by the small servers
as a loss network, each loss corresponding to a request to the data center.
Based on large system / storage behavior, we obtain an asymptotic formula for
the optimal replication of contents and propose adaptive schemes related to
those encountered in cache networks but reacting here to loss events, and
faster algorithms generating virtual events at higher rate while keeping the
same target replication. We show through simulations that our adaptive schemes
outperform significantly standard replication strategies both in terms of loss
rates and adaptation speed.


title: Simple linear algorithms for mining graph cores

abstract:
  Batagelj and Zaversnik proposed a linear algorithm for the well-known
$k$-core decomposition problem. However, when $k$-cores are desired for a given
$k$, we find that a simple linear algorithm requiring no sorting works for
mining $k$-cores. In addition, this algorithm can be extended to mine $(k_1,
k_2,\ldots, k_p)$-cores from $p$-partite graphs in linear time, and this mining
approach can be efficiently implemented in a distributed computing environment
with a lower message complexity bound in comparison with the best known method
of distributed $k$-core decomposition.


title: Nanoscale Phenomena in Oxide Heterostructures

abstract:
  Recent advances in creating complex oxide heterostructures, interfaces formed
between two different transition metal oxides, have heralded a new era of
materials and physics research, enabling a uniquely diverse set of coexisting
physical properties to be combined with an ever- increasing degree of
experimental control. Already, these systems have exhibited such varied
phenomena as superconductivity, magnetism, and ferroelasticity, all of which
are gate-tunable, demonstrating their promise for fundamental discovery and
technological innovation alike. To fully exploit this richness, it is necessary
to understand and control the physics on the smallest scales, making the use of
nanoscale probes essential. Using the prototypical LaAlO$_3$/SrTiO$_3$
interface as a guide, we explore the exciting developments in the physics of
oxide-based heterostructures, with a focus on nanostructures and the nanoscale
probes employed to unravel their complex behavior.


title: Relating $p$-adic eigenvalues and the local Smith normal form

abstract:
  Conditions are established under which the $p$-adic valuations of the
invariant factors (diagonal entries of the Smith form) of an integer matrix are
equal to the $p$-adic valuations of the eigenvalues. It is then shown that this
correspondence is the typical case for "most" matrices; precise density bounds
are given for when the property holds, as well as easy transformations to this
typical case.


title:
On geometrically defined extensions of the Temperley-Lieb category in
  the Brauer category

abstract:
  We define an infinite chain of subcategories of the partition category by
introducing the left-height ($l$) of a partition. For the Brauer case, the
chain starts with the Temperley-Lieb ($l=-1$) and ends with the Brauer
($l=\infty$) category. The End sets are algebras, i.e., an infinite tower
thereof for each $l$, whose representation theory is studied in the paper.


title: Searching for an elusive charged Higgs at the Large Hadron Collider

abstract:
  We study the signals for a "fermiophobic" charged Higgs boson present in an
extension of the standard model with an additional Higgs doublet and right
handed neutrinos, responsible for generating Dirac-type neutrino masses. We
study the pair production of the charged Higgs at the Large Hadron Collider
(LHC), which can be relatively light and still allowed by experimental data.
The charged Higgs decays dominantly into a $W$ boson and a very light neutral
scalar present in the model, which decays invisibly and passes undetected. We
find that the signal for such a charged Higgs is overwhelmed by the standard
model background and will prove elusive at the 8 TeV run of the LHC. We present
a cut-flow based analysis to pinpoint a search strategy at the 14 TeV run of
the LHC which can achieve a signal significance of 5$\sigma$ for a given mass
range of the charged Higgs.


title: Holomorphic differentials and Laguerre deformation of surfaces

abstract:
  A Laguerre geometric local characterization is given of L-minimal surfaces
and Laguerre deformations (T-transforms) of L-minimal isothermic surfaces in
terms of the holomorphicity of a quartic and a quadratic differential. This is
used to prove that, via their Laguerre Gauss maps, the T-transforms of
L-minimal isothermic surfaces have constant mean curvature in some translate of
hyperbolic 3-space or de Sitter 3-space in Minkowski 4-space, or have mean
curvature zero in some translate of a time-oriented lightcone in Minkowski
4-space. As an application, we show that various instances of the Lawson
isometric correspondence can be viewed as special cases of the T-transformation
of L-isothermic surfaces with holomorphic quartic differential.


title: Spherical actions on flag varieties

abstract:
  For every finite-dimensional vector space V and every V-flag variety X we
list all connected reductive subgroups in GL(V) acting spherically on X.


title: Large Scale Visual Recommendations From Street Fashion Images

abstract:
  We describe a completely automated large scale visual recommendation system
for fashion. Our focus is to efficiently harness the availability of large
quantities of online fashion images and their rich meta-data. Specifically, we
propose four data driven models in the form of Complementary Nearest Neighbor
Consensus, Gaussian Mixture Models, Texture Agnostic Retrieval and Markov Chain
LDA for solving this problem. We analyze relative merits and pitfalls of these
algorithms through extensive experimentation on a large-scale data set and
baseline them against existing ideas from color science. We also illustrate key
fashion insights learned through these experiments and show how they can be
employed to design better recommendation systems. Finally, we also outline a
large-scale annotated data set of fashion images (Fashion-136K) that can be
exploited for future vision research.


title:
Towards Space Solar Power - Examining Atmospheric Interactions of Power
  Beams with the HAARP Facility

abstract:
  In the most common space solar power (SSP) system architectures, solar energy
harvested by large satellites in geostationary orbit is transmitted to Earth
via microwave radiation. Currently, only limited information about the
interactions of microwave beams with energy densities of several tens to
hundreds of W/m$^2$ with the different layers of the atmosphere is available.
Governmental bodies will likely require detailed investigations of safety and
atmospheric effects of microwave power beams before issuing launch licenses for
SSP satellite systems. This paper proposes to collect representative and
comprehensive data of the interaction of power beams with the atmosphere by
extending the infrastructure of the High Frequency Active Auroral Research
Program (HAARP) facility in Alaska, USA. Estimates of the transmission
infrastructure performance as well as measurement devices and scientific
capabilities of possible upgrade scenarios will be discussed. The proposed
upgrade of the HAARP facility is expected to deliver a wealth of data and
information which could serve as a decision base for governmental launch
licensing of SSP satellites, and which can be used in addition to deepen public
acceptance of SSP as a large-scale renewable energy source.
  Copyright 2014 IEEE. Personal use of this material is permitted. Permission
from IEEE must be obtained for all other uses, in any current or future media,
including reprinting/republishing this material for advertising or promotional
purposes, creating new collective works, for resale or redistribution to
servers or lists, or reuse of any copyrighted component of this work in other
works.


title: Designing Poincare Series for Number Theoretic Applications

abstract:
  The $GL_2$ Poincar\'{e} series giving the subconvexity results of Diaconu and
Garrett is the solution to an automorphic partial differential equation,
constructed by winding-up the solution to the corresponding differential
equation on the free space. Generalizing this approach allows design of higher
rank Poincar\'{e} series with specific number theoretic applications in mind: a
Poincar\'{e} series for producing an explicit formula for the number of lattice
points in an expanding region in a symmetric space, a Poincar\'{e} series
producing moments of $GL_n \times GL_n$ L-functions, and a Poincar\'{e} series
designed for applications involving pseudo-Laplacians.


title: A Banach space with a countable infinite number of complex structures

abstract:
  We give examples of real Banach spaces with exactly infinite countably many
complex structures and with $\omega_1$ many complex structures.


title: GUTs without guts

abstract:
  The structure of a Standard Model family is derived in a class of brane
models with a U(M) x U(N) factor, from two mildly anthropic requirements: a
massless photon and a universe that does not turn into a plasma of massless
charged particles. If we choose M=3 and N=2, the only option is shown to be the
Standard Model with an undetermined number of families. We do not assume the
U(1) embedding, charge quantization, family repetition, nor the fermion
representations; all of these features are derived, assuming a doublet Higgs.
With a slightly stronger assumption even the Higgs representation is
determined. We also consider a more general class, requiring an asymptotically
free strong SU(M) (with M geq 3) interaction from the first factor and an
electromagnetic U(1) embedded in both factors. We allow Higgs symmetry breaking
of the U(N)x U(1) flavor group by at most one Higgs boson in any
representation, combined with any allowed chiral symmetry breaking by SU(M).
For M=3 there is a large number of solutions with an unbroken U(1). In all of
these, quarks have third-integral charges and color singlets have integer
charges in comparison to leptons. Hence Standard Model charge quantization
holds for any N. Only for N=2 these models allow an SU(5) GUT extension, but
this extension offers no advantages whatsoever for understanding the Standard
Model; it only causes complications, such as the doublet-triplet splitting
problem. Although all these models have a massless photon, all except the
Standard Model are ruled out by the second anthropic requirement. In this class
of brane models the Standard Model is realized as a GUT with its intestines
removed, to keep only the good parts: a GUT without guts.


title:
Identification of $\cal K$ Most Vulnerable Nodes in Multi-layered
  Network Using a New Model of Interdependency

abstract:
  The critical infrastructures of the nation including the power grid and the
communication network are highly interdependent. Recognizing the need for a
deeper understanding of the interdependency in a multi-layered network,
significant efforts have been made by the research community in the last few
years to achieve this goal. Accordingly a number of models have been proposed
and analyzed. Unfortunately, most of the models are over simplified and, as
such, they fail to capture the complex interdependency that exists between
entities of the power grid and the communication networks involving a
combination of conjunctive and disjunctive relations. To overcome the
limitations of existing models, we propose a new model that is able to capture
such complex interdependency relations. Utilizing this model, we provide
techniques to identify the $\cal K$ most vulnerable nodes of an interdependent
network. We show that the problem can be solved in polynomial time in some
special cases, whereas for some others, the problem is NP-complete. We
establish that this problem is equivalent to computation of a {\em fixed point}
of a multilayered network system and we provide a technique for its computation
utilizing Integer Linear Programming. Finally, we evaluate the efficacy of our
technique using real data collected from the power grid and the communication
network that span the Maricopa County of Arizona.


title: On the shape of possible counterexamples to the Jacobian Conjecture

abstract:
  We improve the algebraic methods of Abhyankar for the Jacobian Conjecture in
dimension two and describe the shape of possible counterexamples. We give an
elementary proof of the result of Heitmann, which states that
gcd(deg(P),deg(Q)) is greater than or equal to 16 for any counterexample (P,Q).
We also prove that gcd(deg(P),deg(Q)) \ne 2p for any prime p and analyze
thoroughly the case 16, adapting a reduction of degree technique introduced by
Moh.


title:
A novel variability-based method for quasar selection: evidence for a
  rest frame ~54 day characteristic timescale

abstract:
  We compare quasar selection techniques based on their optical variability
using data from the Catalina Real-time Transient Survey (CRTS). We introduce a
new technique based on Slepian wavelet variance (SWV) that shows comparable or
better performance to structure functions and damped random walk models but
with fewer assumptions. Combining these methods with WISE mid-IR colors
produces a highly efficient quasar selection technique which we have validated
spectroscopically. The SWV technique also identifies characteristic timescales
in a time series and we find a characteristic rest frame timescale of ~54 days,
confirmed in the light curves of ~18000 quasars from CRTS, SDSS and MACHO data,
and anticorrelated with absolute magnitude. This indicates a transition between
a damped random walk and $P(f) \propto f^{-1/3}$ behaviours and is the first
strong indication that a damped random walk model may be too simplistic to
describe optical quasar variability.


title:
Quantum Statistical Mechanics. I. Decoherence, Wave Function Collapse,
  and the von Neumann Density Matrix

abstract:
  The probability operator is derived from first principles for an equilibrium
quantum system. It is also shown that the superposition states collapse into a
mixture of states giving the conventional von Neumann trace form for the
quantum average. The mechanism for the collapse is found to be quite general:
it results from the conservation law for a conserved, exchangeable variable
(such as energy) and the entanglement of the total system wave function that
necessarily follows. The relevance of the present results to the einselection
mechanism for decoherence, to the quantum measurement problem, and to the
classical nature of the macroscopic world are discussed.


title: Quantum Statistical Mechanics. II. Stochastic Schrodinger Equation

abstract:
  The stochastic dissipative Schrodinger equation is derived for an open
quantum system consisting of a sub-system able to exchange energy with a
thermal reservoir. The resultant evolution of the wave function also gives the
evolution of the density matrix, which is an explicit, stochastic form of the
Lindblad master equation. A quantum fluctuation-dissipation theorem is also
derived. The time correlation function is discussed.


title: Phonon Density of States and Anharmonicity of UO2

abstract:
  Phonon density of states (PDOS) measurements have been performed on
polycrystalline UO2 at 295 and 1200 K using time-of-flight inelastic neutron
scattering to investigate the impact of anharmonicity on the vibrational
spectra and to benchmark ab initio PDOS simulations performed on this strongly
correlated Mott-insulator. Time-of-flight PDOS measurements include anharmonic
linewidth broadening inherently and the factor of ~ 7 enhancement of the oxygen
spectrum relative to the uranium component by the neutron weighting increases
sensitivity to the oxygen-dominated optical phonon modes. The first-principles
simulations of quasi-harmonic PDOS spectra were neutron-weighted and
anharmonicity was introduced in an approximate way by convolution with
wavevector-weighted averages over our previously measured phonon linewidths for
UO2 that are provided in numerical form. Comparisons between the PDOS
measurements and the simulations show reasonable agreement overall, but they
also reveal important areas of disagreement for both high and low temperatures.
The discrepancies stem largely from an ~ 10 meV compression in the overall
bandwidth (energy range) of the oxygen-dominated optical phonons in the
simulations. A similar linewidth-convoluted comparison performed with the PDOS
spectrum of Dolling et al. obtained by shell-model fitting to their historical
phonon dispersion measurements shows excellent agreement with the
time-of-flight PDOS measurements reported here. In contrast, we show by
comparisons of spectra in linewidth-convoluted form that recent
first-principles simulations for UO2 fail to account for the PDOS spectrum
determined from the measurements of Dolling et al. These results demonstrate
PDOS measurements to be stringent tests for ab initio simulations of phonon
physics in UO2 and they indicate further the need for advances in theory to
address lattice dynamics of UO2.


title: Mean field games systems of first order

abstract:
  We consider a system of mean field games with local coupling in the
deterministic limit. Under general structure conditions on the Hamiltonian and
coupling, we prove existence and uniqueness of the weak solution,
characterizing this solution as the minimizer of some optimal control of
Hamilton-Jacobi and continuity equations. We also prove that this solution
converges in the long time average to the solution of the associated ergodic
problem.


title: Protein-induced membrane curvature changes membrane tension

abstract:
  Adsorption of proteins onto membranes can alter the local membrane curvature.
This phenomenon has been observed in biological processes such as endocytosis,
tubulation and vesiculation. However, it is not clear how the local surface
properties of the membrane, such as membrane tension, change in response to
protein adsorption. In this paper, we show that the classical elastic model of
lipid membranes cannot account for simultaneous changes in shape and membrane
tension due to protein adsorption in a local region, and a viscous-elastic
formulation is necessary to fully describe the system. Therefore, we develop a
viscous-elastic model for inhomogeneous membranes of the Helfrich type. Using
the new viscous-elastic model, we find that the lipids flow to accommodate
changes in membrane curvature during protein adsorption. We show that, at the
end of protein adsorption process, the system sustains a residual local tension
to balance the difference between the actual mean curvature and the imposed
spontaneous curvatures. This change in membrane tension can have a functional
impact in many biological phenomena where proteins interact with membranes.

categories: q-bio.CB cond-mat.soft cond-mat.stat-mech physics.bio-ph


title: Weak decays of $\bar B_s$ mesons

abstract:
  In the present work we study the semileptonic decays of $\bar B_s$ mesons in
the context of nonrelativistic constituent quark models. We estimate the
uncertainties of our calculation using different interquark potentials to
obtain the meson wave functions. We check the results from our model against
the predictions of Heavy Quark Symmetry, in the limit of infinite heavy quark
mass. We also study the nonleptonic decays of $\bar B_s$ mesons within the
factorization approximation.


title:
Primal-dual subgradient methods for minimizing uniformly convex
  functions

abstract:
  We discuss non-Euclidean deterministic and stochastic algorithms for
optimization problems with strongly and uniformly convex objectives. We provide
accuracy bounds for the performance of these algorithms and design methods
which are adaptive with respect to the parameters of strong or uniform
convexity of the objective: in the case when the total number of iterations $N$
is fixed, their accuracy coincides, up to a logarithmic in $N$ factor with the
accuracy of optimal algorithms.


title: No finite $5$-regular matchstick graph exists

abstract:
  A graph $G=(V,E)$ is called a unit-distance graph in the plane if there is an
injective embedding of $V$ in the plane such that every pair of adjacent
vertices are at unit distance apart. If additionally the corresponding edges
are non-crossing and all vertices have the same degree $r$ we talk of a regular
matchstick graph. Due to Euler's polyhedron formula we have $r\le 5$. The
smallest known $4$-regular matchstick graph is the so called Harborth graph
consisting of $52$ vertices. In this article we prove that no finite
$5$-regular matchstick graph exists.


title:
The Spin of the Black Hole GS 1124-683: Observation of a Retrograde
  Accretion Disk?

abstract:
  We re-examine archival Ginga data for the black hole binary system GS
1124-683, obtained when the system was undergoing its 1991 outburst. Our
analysis estimates the dimensionless spin parameter a=cJ/GM^2 by fitting the
X-ray continuum spectra obtained while the system was in the "Thermal Dominant"
state. For likely values of mass and distance, we find the spin to be a=-0.25
(-0.64, +0.05) (90% confidence), implying that the disk is retrograde (i.e.
rotating antiparallel to the spin axis of the black hole). We note that this
measurement would be better constrained if the distance to the binary and the
mass of the black hole were more accurately determined. This result is
unaffected by the model used to fit the hard component of the spectrum. In
order to be able to recover a prograde spin, the mass of the black hole would
need to be at least 15.25 Msun, or the distance would need to be less than 4.5
kpc, both of which disagree with previous determinations of the black hole mass
and distance. If we allow f_col to be free, we obtain no useful spin
constraint. We discuss our results in the context of recent spin measurements
and implications for jet production.


title: Physical Constraints On Fast Radio Burst

abstract:
  Fast Radio Bursts (FRBs) are isolated, $\ms$ radio pulses with dispersion
measure (DM) of order $10^3\DMunit$. Galactic candidates for the DM of high
latitude bursts detected at $\GHz$ frequencies are easily dismissed. DM from
bursts emitted in stellar coronas are limited by free-free absorption and those
from HII regions are bounded by the nondetection of associated free-free
emission at radio wavelengths. Thus, if astronomical, FRBs are probably
extra-galactic. FRB 110220 has a scattering tail of $\sim 5.6\pm 0.1 \ms$. If
the electron density fluctuations arise from a turbulent cascade, the
scattering is unlikely to be due to propagation through the diffuse
intergalactic plasma. A more plausible explanation is that this burst sits in
the central region of its host galaxy. Pulse durations of order $\ms$ constrain
the sizes of FRB sources implying high brightness temperatures that indicates
coherent emission. Electric fields near FRBs at cosmological distances would be
so strong that they could accelerate free electrons from rest to relativistic
energies in a single wave period.


title:
Friedel Oscillation-Induced Energy Gap Manifested as Transport Asymmetry
  at Monolayer-Bilayer Graphene Boundaries

abstract:
  We show that Friedel charge oscillation near an interface opens a gap at the
Fermi energy for electrons with wave vectors perpendicular to the interface. If
the Friedel gaps on two sides of the interface are different, a nonequlibrium
effect - shifting of these gaps under bias - leads to asymmetric transport upon
reversing the bias polarity. The predicted transport asymmetry is revealed by
scanning tunneling potentiometry at monolayer-bilayer interfaces in epitaxial
graphene on SiC (0001). This intriguing interfacial transport behavior opens a
new avenue towards novel quantum functions such as quantum switching.


title: Black hole for the Einstein-Chern-Simons gravity

abstract:
  We consider a 5-dimensional action which is composed of a gravitational
sector and a sector of matter, where the gravitational sector is given by a
Einstein-Chern-Simons gravity action instead of the Einstein-Hilbert action. We
obtain the Einstein-Chern-Simons (EChS) field equations together with its
spherically sym- metric solution, which leads, in certain limit, to the
standard five dimensional solution of the Einstein-Cartan field equations. It
is found the conditions under which the EChS field equations admits black hole
type solutions. The maximal extension and conformal compactification are also
studied


title:
Uncovering low-dimensional, miR-based signatures of acute myeloid and
  lymphoblastic leukemias with a machine-learning-driven network approach

abstract:
  Complex phenotypic differences among different acute leukemias cannot be
fully captured by analyzing the expression levels of one single molecule, such
as a miR, at a time, but requires systematic analysis of large sets of miRs.
While a popular approach for analysis of such datasets is principal component
analysis (PCA), this method is not designed to optimally discriminate different
phenotypes. Moreover, PCA and other low-dimensional representation methods
yield linear or non-linear combinations of all measured miRs. Global human miR
expression was measured in AML, B-ALL, and T-ALL cell lines and patient RNA
samples. By systematically applying support vector machines to all measured
miRs taken in dyad and triad groups, we built miR networks using cell line data
and validated our findings with primary patient samples. All the coordinately
transcribed members of the miR-23a cluster (which includes also miR-24 and
miR-27a), known to function as tumor suppressors of acute leukemias, appeared
in the AML, B-ALL and T-ALL centric networks. Subsequent qRT-PCR analysis
showed that the most connected miR in the B-ALL-centric network, miR-708, is
highly and specifically expressed in B-ALLs, suggesting that miR-708 might
serve as a biomarker for B-ALL. This approach is systematic, quantitative,
scalable, and unbiased. Rather than a single signature, our approach yields a
network of signatures reflecting the redundant nature of biological signaling
pathways. The network representation allows for visual analysis of all
signatures by an expert and for future integration of additional information.
Furthermore, each signature involves only small sets of miRs, such as dyads and
triads, which are well suited for in depth validation through laboratory
experiments such as loss- and gain-of-function assays designed to drive changes
in leukemia cell survival, proliferation and differentiation.


title: Regular finite planar maps with equal edges

abstract:
  There doesn't exists a finite planar map with all edges having the same
length, and each vertex on exactly 5 edges.


title: G\"odel, Tarski, Turing and the conundrum of free will

abstract:
  The problem of defining and locating free will (FW) in physics is studied. On
basis of logical paradoxes, we argue that FW has a meta-theoretic character,
like the concept of truth in Tarski's undefinability theorem. Free will exists
relative to a base theory if there is freedom to deviate from the deterministic
or indeterministic dynamics in the theory, with the deviations caused by
parameters (representing will) in the meta-theory. By contrast, determinism and
indeterminism do not require meta-theoretic considerations in their
formalization, making FW a fundamentally new causal primitive. FW exists
relative to the meta-theory if there is freedom for deviation, due to
higher-order causes. Absolute free will, which corresponds to our intuitive
introspective notion of free will, exists if this meta-theoretic hierarchy is
infinite. We argue that this hierarchy corresponds to higher levels of
uncomputability. In other words, at any finitely high order in the hierarchy,
there are uncomputable deviations from the law at that order. Applied to the
human condition, the hierarchy corresponds to deeper levels of the subconscious
or unconscious mind. Possible ramifications of our model for physics,
neuroscience and artificial intelligence (AI) are briefly considered.


title: Strain-induced gap modification in black phosphorus

abstract:
  The band structure of single-layer black phosphorus and the effect of strain
are predicted using density functional theory and tight-binding models. Having
determined the localized orbital composition of the individual bands from
first-principles, we use the system symmetry to write down the effective
low-energy Hamiltonian at the $\Gamma$ point. From numerical calculations and
arguments based on the crystal structure of the material, we show that the
deformation in the direction normal to the plane can be use to change the gap
size and induce a semiconductor-metal transition.


title: Quotients of index two and general quotients in a space of orderings

abstract:
  In our work we investigate quotient structures and quotient spaces of a space
of orderings arising from subgroups of index two. We provide necessary and
sufficient conditions for a quotient structure to be a quotient space that,
among other things, depend on the stability index of the given space. The case
of the space of orderings of the field Q(x) is particularly interesting, since
then the theory developed simplifies significantly. A part of the theory
firstly developed for quotients of index 2 generalizes in an elegant way to
quotients of index 2^n for arbitrary finite n. Numerous examples are provided.


title:
Learning Multilingual Word Representations using a Bag-of-Words
  Autoencoder

abstract:
  Recent work on learning multilingual word representations usually relies on
the use of word-level alignements (e.g. infered with the help of GIZA++)
between translated sentences, in order to align the word embeddings in
different languages. In this workshop paper, we investigate an autoencoder
model for learning multilingual word representations that does without such
word-level alignements. The autoencoder is trained to reconstruct the
bag-of-word representation of given sentence from an encoded representation
extracted from its translation. We evaluate our approach on a multilingual
document classification task, where labeled data is available only for one
language (e.g. English) while classification must be performed in a different
language (e.g. French). In our experiments, we observe that our method compares
favorably with a previously proposed method that exploits word-level alignments
to learn word representations.


title: Chebyshev type inequalities for Hilbert space operators

abstract:
  We establish several operator extensions of the Chebyshev inequality. The
main version deals with the Hadamard product of Hilbert space operators. More
precisely, we prove that if $\mathscr{A}$ is a $C^*$-algebra, $T$ is a compact
Hausdorff space equipped with a Radon measure $\mu$, $\alpha: T\rightarrow [0,
+\infty)$ is a measurable function and $(A_t)_{t\in T}, (B_t)_{t\in T}$ are
suitable continuous fields of operators in ${\mathscr A}$ having the
synchronous Hadamard property, then \begin{align*} \int_{T} \alpha(s)
d\mu(s)\int_{T}\alpha(t)(A_t\circ B_t) d\mu(t)\geq\left(\int_{T}\alpha(t) A_t
d\mu(t)\right)\circ\left(\int_{T}\alpha(s) B_s d\mu(s)\right).
  \end{align*} We apply states on $C^*$-algebras to obtain some versions
related to synchronous functions. We also present some Chebyshev type
inequalities involving the singular values of positive $n\times n$ matrices.
Several applications are given as well.


title: Maximal percentages in Polya's urn

abstract:
  We show that the supremum of the successive percentages of red balls in
P\'olya's urn model is almost surely rational, give the set of values that are
taken with positive probability and derive several exact distributional results
for the all-time maximal percentage.


title:
Coherence effects between the initial and final state radiation in a
  dense QCD medium

abstract:
  In these proceedings contribution we review our recent results of medium
modifications to the coherence pattern between the initial and final state
radiation. We study single gluon production off a highly energetic parton that
undergoes a hard scattering and subsequently crosses a dense QCD medium of
finite size. Multiple scatterings lead to a partial suppression of the
interferences between different emitters that opens the phase space for large
angle emissions. We briefly discuss the generalization of this setup to
describe gluon production in the case of pA collisions by including finite
length and energy corrections. The configuration studied here may have
phenomenological consequences in high-energy nuclear collisions.


title: Light cone anisotropy in 21 cm signal from the epoch of reionization

abstract:
  Using a suite of detailed numerical simulations we estimate the level of
anisotropy generated by the time evolution along the light cone of the 21cm
signal from the epoch of reionization. Our simulations include the physics
necessary to model the signal during both the late emission regime and the
early absorption regime, namely X-ray and Lyman-band 3D radiative transfer in
addition to the usual dynamics and ionizing UV transfer. The signal is analysed
using correlation functions perpendicular and parallel to the line of sight
(LOS). We reproduce general findings from previous theoretical studies: the
overall amplitude of the correlations and the fact that the light cone
anisotropy is visible only on large scales (100 cMpc). However, the detailed
behaviour is different. At 3 different epochs, the amplitude of the
correlations along and perpendicular to the LOS differ from each other,
indicating anisotropy. These 3 epochs are associated with 3 events of the
global reionization history: the overlap of ionized bubbles, the onset of mild
heating by X-rays in regions around the sources, and the onset of efficient
Lyman-alpha coupling in regions around the sources. A 20x20 deg^2 survey area
may be necessary to mitigate sample variance when we use the directional
correlation functions. On a 100 cMpc scale the light cone anisotropy dominates
over the anisotropy generated by peculiar velocity gradients computed in the
linear regime. By modelling instrumental noise and limited resolution, we find
that the anisotropy should be easily detectable by the SKA, assuming perfect
foreground removal, the limiting factor being a large enough survey size. In
the case of the LOFAR, it is likely that only first anisotropy episode will
fall in the observing frequency range and will be detectable only if sample
variance is much reduced (i.e. a larger than 20x20 deg^2 survey, which is not
presently planned).


title: Using biophotonics to study signaling mechanisms in a single living cell

abstract:
  To illustrate the power of the biophysical approach in solving important
problems in life science, I present here one of our current research projects
as an example. We have developed special biophotonic techniques to study the
dynamic properties of signaling proteins in a single living cell. Such a study
allowed us to gain new insight into the signaling mechanism that regulates
programmed cell death.


title:
The Evolution of Protostars: Insights from Ten Years of Infrared Surveys
  with Spitzer and Herschel

abstract:
  Stars form from the gravitational collapse of dense molecular cloud cores. In
the protostellar phase, mass accretes from the core onto a protostar, likely
through an accretion disk, and it is during this phase that the initial masses
of stars and the initial conditions for planet formation are set. Over the past
decade, new observational capabilities provided by the Spitzer Space Telescope
and Herschel Space Observatory have enabled wide-field surveys of entire
star-forming clouds with unprecedented sensitivity, resolution, and infrared
wavelength coverage. We review resulting advances in the field, focusing both
on the observations themselves and the constraints they place on theoretical
models of star formation and protostellar evolution. We also emphasize open
questions and outline new directions needed to further advance the field.


title: Covariant Non-Commutative Space-Time

abstract:
  We introduce a covariant non-commutative deformation of 3+1-dimensional
conformal field theory. The deformation depends on a short-distance scale
\ell_p, and thus breaks scale invariance, but preserves all space-time
isometries. The non-commutative algebra is defined on space-times with non-zero
constant curvature, i.e. dS_4 or AdS_4. The construction makes essential use of
the representation of CFT tensor operators as polynomials in an auxiliary
polarization tensor. The polarization tensor takes active part in the
non-commutative algebra, which for dS_4 takes the form of so(5,1), while for
AdS_4 it assembles into so(4,2). The structure of the non-commutative
correlation functions hints that the deformed theory contains gravitational
interactions and a Regge-like trajectory of higher spin excitations.


title:
Galactic and Circumgalactic OVI and its Impact on the Cosmological Metal
  and Baryon Budgets at 2<z<3.5

abstract:
  We present the first results from our NASA Keck Observatory Database of
Ionized Absorbers toward Quasars (KODIAQ) survey which aims to characterize the
properties of the highly ionized gas of high redshift galaxies and their
circumgalactic medium (CGM) at 2<z<4. We select absorbers optically thick at
the Lyman limit ({\tau}LL > 1, log N(HI) > 17.3) as probes of these galaxies
and their CGM where both transitions of the O VI doublet have little
contamination from the Ly {\alpha}, {\beta} forests. We found 20 absorbers that
satisfy these rules: 7 Lyman limit systems (LLSs), 8 super-LLSs (SLLSs) and 5
damped Ly{\alpha} (DLAs). The O VI detection rate is 100% for the DLAs, 71% for
the LLSs, and 63% for the SLLSs. When O VI is detected, log N(OVI)=14.9+/-0.3,
an average O VI column density substantially larger and with a smaller
dispersion than found in blind O VI surveys at similar redshifts. Strong O VI
absorption is therefore nearly ubiquitous in the CGM of z~2-3 galaxies. The
total velocity widths of the O VI profiles are also large (200<Dv(OVI)<400
km/s). These properties are quite similar to those seen for O VI in low z
star-forming galaxies, and therefore we hypothesize that these strong CGM O VI
absorbers (with {\tau}LL > 1) at 2<z<3.5 also probe outflows of star-forming
galaxies. The LLSs and SLLSs with no O VI absorption have properties consistent
with those seen in cosmological simulations tracing cold streams feeding
galaxies. When the highly ionized (Si IV and O VI) gas is taken into account,
we determine that the {\tau}LL > 1 absorbers could contain as much as 3-14% of
the cosmic baryon budget at z~2-3, only second to the Ly{\alpha} forest. We
conservatively show that 5-20% of the metals ever produced at z~2-3 are in form
of highly ionized metals ejected in the CGM of galaxies.


title: Cold stream stability during minor mergers

abstract:
  We use high-resolution Eulerian simulations to study the stability of cold
gas flows in a galaxy size dark matter halo (10^12 Msun) at redshift z=2. Our
simulations show that a cold stream penetrating a hot gaseous halo is stable
against thermal convection and Kelvin-Helmholtz instability. We then
investigate the effect of a satellite orbiting the main halo in the plane of
the stream. The satellite is able to perturb the stream and to inhibit cold gas
accretion towards the center of the halo for 0.5 Gyr. However, if the supply of
cold gas at large distances is kept constant, the cold stream is able to
re-establish itself after 0.3 Gyr. We conclude that cold streams are very
stable against a large variety of internal and external perturbations.


title:
Effect of rotational disruption on the size-frequency distribution of
  the Main Belt asteroid population

abstract:
  The size distribution of small asteroids in the Main Belt is assumed to be
determined by an equilibrium between the creation of new bodies out of the
impact debris of larger asteroids and the destruction of small asteroids by
collisions with smaller projectiles. However, for a diameter less than 6 km we
find that YORP-induced rotational disruption significantly contributes to the
erosion even exceeding the effects of collisional fragmentation. Including this
additional grinding mechanism in a collision evolution model for the asteroid
belt, we generate size-frequency distributions from either an accretional
(Weidenschilling, 2011) or an "Asteroids were born big" (Morbidelli, 2009)
initial size-frequency distribution that are consistent with observations
reported in Gladman et al. (2009). Rotational disruption is a new mechanism
that must be included in all future collisional evolution models of asteroids.


title: The Astronomical Reach of Fundamental Physics

abstract:
  Using basic physical arguments, we derive by dimensional and physical
analysis the characteristic masses and sizes of important objects in the
Universe in terms of just a few fundamental constants. This exercise
illustrates the unifying power of physics and the profound connections between
the small and the large in the Cosmos we inhabit. We focus on the minimum and
maximum masses of normal stars, the corresponding quantities for neutron stars,
the maximum mass of a rocky planet, the maximum mass of a white dwarf, and the
mass of a typical galaxy. To zeroth order, we show that all these masses can be
expressed in terms of either the Planck mass or the Chandrasekar mass, in
combination with various dimensionless quantities. With these examples we
expose the deep interrelationships imposed by Nature between disparate realms
of the Universe and the amazing consequences of the unifying character of
physical law.


title: Quantum-Number Exotic Tetraquarks at Large $N_c$ in QCD(AS)

abstract:
  It is shown that the large $N_c$ limit of QCD with quarks in the two-index
antisymmetric color representation [QCD(AS)] has narrow tetraquark states with
exotic flavor quantum numbers. They decay into mesons with a width that is
parametrically $O(1/N_c^2)$. Tetraquarks with non-exotic quantum numbers mix at
leading order with mesons of the same overall quantum numbers. QCD(AS) at
$N_c=3$ corresponds to ordinary QCD; its large $N_c$ limit represents an
alternative starting point for a $1/N_c$ expansion to the standard one with
quarks in the fundamental color representation.


title: A precision study of the fine tuning in the DiracNMSSM

abstract:
  Recently the DiracNMSSM has been proposed as a possible solution to reduce
the fine tuning in supersymmetry. We determine the degree of fine tuning needed
in the DiracNMSSM with and without non-universal gaugino masses and compare it
with the fine tuning in the GNMSSM. To apply reasonable cuts on the allowed
parameter regions we perform a precise calculation of the Higgs mass. In
addition, we include the limits from direct SUSY searches and dark matter
abundance. We find that both models are comparable in terms of fine tuning,
with the minimal fine tuning in the GNMSSM slightly smaller.


title:
Galaxy And Mass Assembly (GAMA): ugrizYJHK S\'ersic luminosity functions
  and the cosmic spectral energy distribution by Hubble type

abstract:
  We report the morphological classification of 3727 galaxies from the Galaxy
and Mass Assembly survey with M_r < -17.4 mag and in the redshift range 0.025 <
z < 0.06 (2.1 x 10^5 Mpc^3 ) into E, S0-Sa, SB0-SBa, Sab-Scd, SBab-SBcd, Sd-Irr
and little blue spheroid classes. Approximately 70% of galaxies in our sample
are disk dominated systems, with the remaining ~30% spheroid dominated. We
establish the robustness of our classifications, and use them to derive
morphological-type luminosity functions and luminosity densities in the
ugrizYJHK passbands, improving on prior studies that split by global colour or
light profile shape alone. We find that the total galaxy luminosity function is
best described by a double-Schechter function while the constituent
morphological-type luminosity functions are well described by a
single-Schechter function.
  These data are also used to derive the star-formation rate densities for each
Hubble class, and the attenuated and unattenuated (corrected for dust) cosmic
spectral energy distributions, i.e., the instantaneous energy production
budget. While the observed optical/near-IR energy budget is dominated 58:42 by
galaxies with a significant spheroidal component, the actual energy production
rate is reversed, i.e., the combined disk dominated populations generate ~1.3x
as much energy as the spheroid dominated populations. On the grandest scale,
this implies that chemical evolution in the local Universe is currently
confined to mid-type spiral classes like our Milky Way.


title: Neutrino masses in RPV models with two pairs of Higgs doublets

abstract:
  We study the generation of neutrino masses and mixing in supersymmetric
R-parity violating models containing two pairs of Higgs doublets. In these
models, new RPV terms $\hat H_{D_1} \hat H_{D_2} \hat E$ arise in the
superpotential, as well as new soft terms. Such terms give new contributions to
neutrino masses. We identify the different parameters and
suppression/enhancement factors that control each of these contributions. At
tree level, just like in the MSSM, only one neutrino acquires a mass due to
neutrino-neutralino mixing. There are no new one loop effects. We study the two
loop contributions and find the conditions under which they can be important.


title: Efficient algorithm to compute the Berry conductivity

abstract:
  We propose and construct a numerical algorithm to calculate the Berry
conductivity in topological band insulators. The method is applicable to cold
atom systems as well as solid state setups, both for the insulating case where
the Fermi energy lies in the gap between two bulk bands as well as in the
metallic regime and interpolates smoothly between both regimes. The algorithm
is gauge-invariant by construction, efficient and yields the Berry conductivity
with known and controllable statistical error bars. We apply the algorithm to
several paradigmatic models in the field of topological insulators, including
Haldane's model on the honeycomb lattice, the multi-band Hofstadter model and
the BHZ model, which describes the 2D spin Hall effect observed in
CdTe/HgTe/CdTe quantum well heterostructures.


title: Are gamma-ray bursts the sources of ultra-high energy cosmic rays?

abstract:
  We reconsider the possibility that gamma-ray bursts (GRBs) are the sources of
the ultra-high energy cosmic rays (UHECRs) within the internal shock model,
assuming a pure proton composition of the UHECRs. For the first time, we
combine the information from gamma-rays, cosmic rays, prompt neutrinos, and
cosmogenic neutrinos quantitatively in a joint cosmic ray production and
propagation model, and we show that the information on the cosmic energy budget
can be obtained as a consequence. In addition to the neutron model, we consider
alternative scenarios for the cosmic ray escape from the GRBs, i.e., that
cosmic rays can leak from the sources. We find that the dip model, which
describes the ankle in UHECR observations by the pair production dip, is
strongly disfavored in combination with the internal shock model because a)
unrealistically high baryonic loadings (energy in protons versus energy in
electrons/gamma-rays) are needed for the individual GRBs and b) the prompt
neutrino flux easily overshoots the corresponding neutrino bound. On the other
hand, GRBs may account for the UHECRs in the ankle transition model if cosmic
rays leak out from the source at the highest energies. In that case, we
demonstrate that future neutrino observations can efficiently test most of the
parameter space -- unless the baryonic loading is much larger than previously
anticipated.


title:
Discovery of a Small Central Disk of CO and HI in the Merger Remnant NGC
  34

abstract:
  We present CO(1-0) and HI(21-cm) observations of the central region of the
wet merger remnant NGC 34. The Combined Array for Research in Millimeter-wave
Astronomy (CARMA) observations detect a regularly rotating disk in CO with a
diameter of 2.1 kpc and a total molecular hydrogen mass of ($2.1 \pm 0.2)
\times10^9~M_\odot$. The rotation curve of this gas disk rises steeply,
reaching maximum velocities at 1" (410 pc) from the center. Interestingly, HI
observations done with the Karl G. Jansky Very Large Array show that the
absorption against the central continuum has the exact same velocity range as
the CO in emission. This strongly suggests that the absorbing HI also lies
within 1" from the center, is mixed in and corotates with the molecular gas. A
comparison of HI absorption profiles taken at different resolutions (5"-45")
shows that the spectra at lower resolutions are less deep at the systemic
velocity. This provides evidence for HI emission in the larger beams, covering
the region from 1 kpc to 9 kpc from the center. The central rapidly rotating
disk was likely formed either during the merger or from fall-back material.
Lastly, the radio continuum flux of the central source at mm wavelengths
($5.4\pm1.8$ mJy) is significantly higher than expected from an extrapolation
of the synchrotron spectrum, indicating the contribution of thermal free-free
emission from the central starburst.


title:
Stellar populations in central cluster galaxies: the influence of
  cooling flows

abstract:
  We present detailed, high spatial and spectral resolution, long-slit
observations of four central cluster galaxies (Abell 0085, 0133, 0644 and
Ophiuchus) recently obtained on the Southern African Large Telescope (SALT).
Our sample consists of central cluster galaxies (CCGs) with previously-observed
H\alpha-filaments, and have existing data from the X-ray to radio wavelength
regimes available. Here, we present the detailed optical data over a broad
wavelength range to probe the spatially-resolved kinematics and stellar
populations of the stars. We use the Pegase.HR model with the ELODIE v3.1
stellar library to determine the star formation histories of the galaxies using
full spectrum fitting. We perform single stellar population (SSP) as well as
composite stellar population (CSP) fits to account for more complex star
formation histories. Monte-Carlo simulations and \chi 2-maps are used to check
the reliability of the solutions. This, combined with the other multiwavelength
data, will form a complete view of the different phases (hot and cold gas and
stars) and how they interact in the processes of star formation and feedback
detected in central galaxies in cooling flow clusters, as well as the influence
of the host cluster. We find small, young stellar components in at least three
of the four galaxies, even though two of the three host clusters have zero
spectrally-derived mass deposition rates from X-ray observations.


title: Tri-Dirac Surface Modes in Topological Superconductors

abstract:
  We propose a new type of topological surface modes having cubic dispersion in
three-dimensional topological superconductors. Lower order dispersions are
prohibited by the threefold rotational symmetry and time-reversal symmetry.
Cooper pairing in the bulk changes sign under improper rotations, akin
to$^{3}$He-B. The surface manifestations are a divergent surface density of
states at the Fermi level and isospins that rotate three times as they circle
the origin in momentum space. We propose that Heusler alloys with band
inversion are candidate materials to harbor the novel topological
superconductivity.


title:
Age and mass segregation of multiple stellar populations in galactic
  nuclei and their observational signatures

abstract:
  Nuclear stellar cluster (NSCs) are known to exist around massive black holes
(MBHs) in galactic nuclei. They are thought to have formed through in-situ star
formation following gas inflow to the nucleus of the galaxy and/or through the
infall of multiple stellar clusters. Here we study the latter, and explore the
composite structure of the NSC, and its relation to the various stellar
populations originating from its progenitor infalling clusters. We use N-body
simulations of clusters infall, and show that this scenario may produce
observational signatures in the form of age segregation: the distribution of
the stellar properties (e.g. stellar age and/or metallicity) in the NSCs
reflect the infall history of the different clusters. The stellar populations
of clusters infalling at different times (dynamical ages), are differentially
segregated in the NSC, and are not fully mixed even after few Gyrs of
evolution. Moreover, the radial properties of stellar populations in the
progenitor cluster are mapped to their radial distribution in the final NSC,
potentially leading to efficient mass segregation in NSCs, even those where
relaxation times are longer than a Hubble time. Finally, the overall structures
of the stellar populations present non-spherical configurations and show
significant cluster to cluster population differences.


title: Probing Light Nonthermal Dark Matter at the LHC

abstract:
  This paper investigates the collider phenomenolgy of a minimal nonthermal
dark matter model with a 1-GeV dark matter candidate, which naturally explain
baryongensis. Since the light dark matter is not parity-protected, it can be
singly produced at the LHC. This leads to large missing energy associated with
an energetic jet whose transverse momentum distribution is featured by a
Jacobian-like shape. The monojet, dijet, paired dijet and 2 jets + missing
energy channels are studied. Currently existing data at Tevatron and LHC offer
significant bounds on our model.