title:
Multiple imputation for continuous variables using a Bayesian principal
  component analysis

abstract:
  We propose a multiple imputation method based on principal component analysis
(PCA) to deal with incomplete continuous data. To reflect the uncertainty of
the parameters from one imputation to the next, we use a Bayesian treatment of
the PCA model. Using a simulation study and real data sets, the method is
compared to two classical approaches: multiple imputation based on joint
modelling and on fully conditional modelling. Contrary to the others, the
proposed method can be easily used on data sets where the number of individuals
is less than the number of variables and when the variables are highly
correlated. In addition, it provides unbiased point estimates of quantities of
interest, such as an expectation, a regression coefficient or a correlation
coefficient, with a smaller mean squared error. Furthermore, the widths of the
confidence intervals built for the quantities of interest are often smaller
whilst ensuring a valid coverage.


title: KAM-tori near an analytic elliptic fixed point

abstract:
  We study the accumulation of an elliptic fixed point of a real analytic
Hamiltonian by quasi-periodic invariant tori. We show that a fixed point with
Diophantine frequency vector $\o_0$ is always accumulated by invariant complex
analytic KAM-tori. Indeed, the following alternative holds: If the Birkhoff
normal form of the Hamiltonian at the invariant point satisfies a R\"ussmann
transversality condition, the fixed point is accumulated by real analytic
KAM-tori which cover positive Lebesgue measure in the phase space (in this part
it suffices to assume that $\o_0$ has rationally independent coordinates). If
the Birkhoff normal form is degenerate, there exists an analytic subvariety of
complex dimension at least $d+1$ passing through 0 that is foliated by complex
analytic KAM-tori with frequency $\omega_0$. This is an extension of previous
results obtained in \cite{EFK} to the case of an elliptic fixed point.


title:
Detecting and quantifying stellar magnetic fields -- Sparse Stokes
  profile approximation using orthogonal matching pursuit

abstract:
  In the recent years, we have seen a rapidly growing number of stellar
magnetic field detections for various types of stars. Many of these magnetic
fields are estimated from spectropolarimetric observations (Stokes V) by using
the so-called center-of-gravity (COG) method. Unfortunately, the accuracy of
this method rapidly deteriorates with increasing noise and thus calls for a
more robust procedure that combines signal detection and field estimation. We
introduce an estimation method that provides not only the effective or mean
longitudinal magnetic field from an observed Stokes V profile but also uses the
net absolute polarization of the profile to obtain an estimate of the apparent
(i.e., velocity resolved) absolute longitudinal magnetic field. By combining
the COG method with an orthogonal-matching-pursuit (OMP) approach, we were able
to decompose observed Stokes profiles with an overcomplete dictionary of
wavelet-basis functions to reliably reconstruct the observed Stokes profiles in
the presence of noise. The elementary wave functions of the sparse
reconstruction process were utilized to estimate the effective longitudinal
magnetic field and the apparent absolute longitudinal magnetic field. A
multiresolution analysis complements the OMP algorithm to provide a robust
detection and estimation method. An extensive Monte-Carlo simulation confirms
the reliability and accuracy of the magnetic OMP approach.


title: Passive Sorting of Asteroid Material Using Solar Radiation Pressure

abstract:
  Understanding dust dynamics in the vicinity of asteroids is key for future
science missions and, in the long-term, for asteroid exploitation. This paper
analyzes the feasibility of manipulating asteroid material by means of solar
radiation pressure. A novel method is proposed for passively sorting material
as a function of its grain size or density, where solar radiation pressure is
used as a passive in-situ "mass spectrometer". A simplified analysis shows that
in principle this method allows an effective sorting of regolith material. This
could have immediate applications for a sample return mission, and for
industrial scale in-situ resource utilization to separate and concentrate
regolith according to particle size or composition.


title: Coherent Imaging Spectroscopy of a Quantum Many-Body Spin System

abstract:
  Quantum simulators, in which well controlled quantum systems are used to
reproduce the dynamics of less understood ones, have the potential to explore
physics that is inaccessible to modeling with classical computers. However,
checking the results of such simulations will also become classically
intractable as system sizes increase. In this work, we introduce and implement
a coherent imaging spectroscopic technique to validate a quantum simulation,
much as magnetic resonance imaging exposes structure in condensed matter. We
use this method to determine the energy levels and interaction strengths of a
fully-connected quantum many-body system. Additionally, we directly measure the
size of the critical energy gap near a quantum phase transition. We expect this
general technique to become an important verification tool for quantum
simulators once experiments advance beyond proof-of-principle demonstrations
and exceed the resources of conventional computers.


title:
Towards a Software Architecture Maturity Model for Improving
  Ultra-Large-Scale Systems Interoperability

abstract:
  For the last two decades, software architecture has been adopted as one of
the main viable solutions to address the ever-increasing demands in the design
and development of software systems. Nevertheless, the rapidly growing
utilization of communication networks and interconnections among software
systems have introduced some critical challenges, which need to be handled in
order to fully unleash the potential of these systems. In this respect,
Ultra-Large-Scale (ULS) systems, generally considered as a system of systems,
have gained considerable attention, since their scale is incomparable to the
traditional systems. The scale of ULS systems makes drastic changes in various
aspects of system development. As a result, it requires that we broaden our
understanding of software architectures and the ways we structure them. In this
paper, we investigate the lack of an architectural maturity model framework for
ULS system interoperability, and propose an architectural maturity model
framework to improve ULS system interoperability.


title:
Worst-Case Scenarios for Greedy, Centrality-Based Network Protection
  Strategies

abstract:
  The task of allocating preventative resources to a computer network in order
to protect against the spread of viruses is addressed. Virus spreading dynamics
are described by a linearized SIS model and protection is framed by an
optimization problem which maximizes the rate at which a virus in the network
is contained given finite resources. One approach to problems of this type
involve greedy heuristics which allocate all resources to the nodes with large
centrality measures. We address the worst case performance of such greedy
algorithms be constructing networks for which these greedy allocations are
arbitrarily inefficient. An example application is presented in which such a
worst case network might arise naturally and our results are verified
numerically by leveraging recent results which allow the exact optimal solution
to be computed via geometric programming.


title:
Tunable interactions between paramagnetic colloidal particles driven in
  a modulated ratchet potential

abstract:
  We study experimentally and theoretically the interactions between
paramagnetic particles dispersed in water and driven above the surface of a
stripe patterned magnetic garnet film. An external rotating magnetic field
modulates the stray field of the garnet film and generates a translating
potential landscape which induces directed particle motion. By varying the
ellipticity of the rotating field, we tune the inter-particle interactions from
net attractive to net repulsive. For attractive interactions, we show that
pairs of particles can approach each other and form stable doublets which
afterwards travel along the modulated landscape at a constant mean speed. We
measure the strength of the attractive force between the moving particles and
propose an analytically tractable model that explains the observations and is
in quantitative agreement with experiment.


title:
Instrumental Variables Estimation with Some Invalid Instruments and its
  Application to Mendelian Randomization

abstract:
  Instrumental variables have been widely used for estimating the causal effect
between exposure and outcome. Conventional estimation methods require complete
knowledge about all the instruments' validity; a valid instrument must not have
a direct effect on the outcome and not be related to unmeasured confounders.
Often, this is impractical as highlighted by Mendelian randomization studies
where genetic markers are used as instruments and complete knowledge about
instruments' validity is equivalent to complete knowledge about the involved
genes' functions.
  In this paper, we propose a method for estimation of causal effects when this
complete knowledge is absent. It is shown that causal effects are identified
and can be estimated as long as less than $50$% of instruments are invalid,
without knowing which of the instruments are invalid. We also introduce
conditions for identification when the 50% threshold is violated. A fast
penalized $\ell_1$ estimation method, called sisVIVE, is introduced for
estimating the causal effect without knowing which instruments are valid, with
theoretical guarantees on its performance. The proposed method is demonstrated
on simulated data and a real Mendelian randomization study concerning the
effect of body mass index on health-related quality of life index. An R package
\emph{sisVIVE} is available online.


title:
Reachability for Partially Observable Discrete Time Stochastic Hybrid
  Systems

abstract:
  When designing optimal controllers for any system, it is often the case that
the true state of the system is unknown to the controller, for example due to
noisy measurements or partially observable states. Incomplete state information
must be taken into account in the controller's design in order to preserve its
optimality. The same is true when performing reachability calculations. To
estimate the probability that the state of a stochastic system reaches, or
stays within, some set of interest in a given time horizon, it is necessary to
find a controller (or at least prove one exists) that drives the system to that
set with maximum probability. This controller, however, does not have access to
the true state of the system. To date, little work has been done on stochastic
reachability calculations with partially observable states. What work has been
done relies on converting the reachability optimization problem to one with an
additive cost function, for which theoretical results are well known. Our
approach is to preserve the multiplicative cost structure when deriving a
sufficient statistic that reduces the problem to one of perfect state
information. Our transformation includes a change of measure that simplifies
the distribution of the sufficient statistic conditioned on its previous value.
We develop a dynamic programming recursion for the solution of the equivalent
perfect information problem, proving that the recursion is valid, an optimal
solution exists, and results in the same solution as to the original problem.
We also show that our results are equivalent to those for the reformulated
additive cost problem, and so such a reformulation is not required.


title: Sensitivity of orbiting JEM-EUSO to large-scale cosmic-ray anisotropies

abstract:
  The two main advantages of space-based observation of extreme-energy
($\gtrsim 10^{19}$~eV) cosmic-rays (EECRs) over ground-based observatories are
the increased field of view, and the all-sky coverage with nearly uniform
systematics of an orbiting observatory. The former guarantees increased
statistics, whereas the latter enables a partitioning of the sky into spherical
harmonics. We have begun an investigation, using the spherical harmonic
technique, of the reach of \J\ into potential anisotropies in the
extreme-energy cosmic-ray sky-map. The technique is explained here, and
simulations are presented. The discovery of anisotropies would help to identify
the long-sought origin of EECRs.


title:
Fitting Spectral Energy Distributions of AGN - A Markov Chain Monte
  Carlo Approach

abstract:
  We present AGNfitter: a Markov Chain Monte Carlo algorithm developed to fit
the spectral energy distributions (SEDs) of active galactic nuclei (AGN) with
different physical models of AGN components. This code is well suited to
determine in a robust way multiple parameters and their uncertainties, which
quantify the physical processes responsible for the panchromatic nature of
active galaxies and quasars. We describe the technicalities of the code and
test its capabilities in the context of X-ray selected obscured AGN using
multiwavelength data from the XMM-COSMOS survey.


title:
Optimal Energy Procurement from a Strategic Seller with Private
  Renewable and Conventional Generation

abstract:
  We consider a mechanism design problem for energy procurement, when there is
one buyer and one seller, and the buyer is the mechanism designer. The seller
can generate energy from conventional (deterministic) and renewable (random)
plants, and has multi-dimensional private information which determines her
production cost. The objective is to maximize the buyer's utility under the
constraint that the seller voluntarily participates in the energy procurement
process. We show that the optimal mechanism is a menu of contracts (nonlinear
pricing) that the buyer offers to the seller, and the seller chooses one based
on her private information.


title:
Vibrational states of a water molecule in a nano-cavity of beryl crystal
  lattice

abstract:
  Low-energy excitations of a single water molecule are studied when confined
within a nano-size cage formed by the ionic crystal lattice. Optical spectra
are measured of manganese doped beryl single crystal Mn:Be3Al2Si6O18, that
contains water molecules individually isolated in 0.51 nm diameter voids within
the crystal lattice. Two types of orientation are distinguished: water-I
molecules have their dipole moments aligned perpendicular to the c axis, and
dipole moments of water-II molecules are parallel to the c-axis. The optical
conductivity and permittivity spectra are recorded in terahertz and infrared
ranges, at frequencies from several wavenumbers up to 7000cm-1, at temperatures
from 5K to 300K and for two polarizations, when the electric vector E of the
radiation is parallel and perpendicular to the c-axis. Comparative experiments
on as-grown and on dehydrated samples allow to identify the conductivity and
permittivity spectra caused exclusively by water molecules. In the infrared
range well-known internal modes nu1, nu2 and nu3 of the H2O molecule are
observed for both polarizations, indicating the presence of water-I and
water-II molecules in the crystal. Spectra recorded below 1000cm-1 reveal a
rich set of highly anisotropic features in the low-energy response of H2O
molecule in a crystalline nanocage. While for E parallel to c only two
absorption peaks are detected, at 90cm-1 and 160cm-1, several absorption bands
are discovered for E perpendicular to c, each consisting of narrower
resonances. The bands are assigned to librational and translational vibrations
of water-I molecule that is weakly, via hydrogen bonds, coupled to the nanocage
walls. A model is presented that explains the fine structure of the bands by
splitting of the energy levels due to quantum tunneling between the minima in a
six-well potential relief felt by a molecule within the cage.


title: Information Preservation and Weather Forecasting for Black Holes

abstract:
  It has been suggested [1] that the resolution of the information paradox for
evaporating black holes is that the holes are surrounded by firewalls, bolts of
outgoing radiation that would destroy any infalling observer. Such firewalls
would break the CPT invariance of quantum gravity and seem to be ruled out on
other grounds. A different resolution of the paradox is proposed, namely that
gravitational collapse produces apparent horizons but no event horizons behind
which information is lost. This proposal is supported by ADS-CFT and is the
only resolution of the paradox compatible with CPT. The collapse to form a
black hole will in general be chaotic and the dual CFT on the boundary of ADS
will be turbulent. Thus, like weather forecasting on Earth, information will
effectively be lost, although there would be no loss of unitarity.


title: Performance Improvements for Nuclear Reaction Network Integration

abstract:
  Aims: The aim of this work is to compare the performance of three reaction
network integration methods used in stellar nucleosynthesis calculations. These
are the Gear's backward differentiation method, Wagoner's method (a 2nd-order
Runge-Kutta method), and the Bader-Deuflehard semi-implicit multi-step method.
  Methods: To investigate the efficiency of each of the integration methods
considered here, a test suite of temperature and density versus time profiles
is used. This suite provides a range of situations ranging from constant
temperature and density to the dramatically varying conditions present in white
dwarf mergers, novae, and x-ray bursts. Some of these profiles are obtained
separately from full hydrodynamic calculations. The integration efficiencies
are investigated with respect to input parameters that constrain the desired
accuracy and precision.
  Results: Gear's backward differentiation method is found to improve accuracy,
performance, and stability in integrating nuclear reaction networks. For
temperature-density profiles that vary strongly with time, it is found to
outperform the Bader-Deuflehard method (although that method is very powerful
for more smoothly varying profiles). Wagoner's method, while relatively fast
for many scenarios, exhibits hard-to-predict inaccuracies for some choices of
integration parameters owing to its lack of error estimations.


title: Long Cycles in 1-tough Graphs

abstract:
  In 1952, Dirac proved that every 2-connected graph with minimum degree
$\delta$ either is hamiltonian or contains a cycle of length at least
$2\delta$. In 1986, Bauer and Schmeichel enlarged the bound $2\delta$ to
$2\delta+2$ under additional 1-tough condition - an alternative and more
natural necessary condition for a graph to be hamiltonian. In fact, the bound
$2\delta+2$ is sharp for a graph on $n$ vertices when $n\equiv 1(mod\ 3)$. In
this paper we present the final version of this result which is sharp for each
$n$: every 1-tough graph either is hamiltonian or contains a cycle of length at
least $2\delta+2$ when $n\equiv 1(mod\ 3)$, at least $2\delta+3$ when $n\equiv
2(mod\ 3)$ or $n\equiv 1(mod\ 4)$, and at least $2\delta+4$ otherwise.


title: On the nature of sn stars. I. A detailed abundance study

abstract:
  The sn stars present sharp Balmer lines, sharp metallic lines and broad
coreless He I lines. Initially Abt & Levato proposed a shell-like nature to
explain the sn stars, although this scenario was subsequently questioned. We
aim to derive abundances for a sample of 9 stars, including sn and non-sn
stars, to determine the possible relation between sn and CP stars. We analysed
the photospheric chemical composition of sn stars and show that approximately
40% of them display chemical peculiarities (such as He-weak and HgMn stars)
within a range of temperature of 10300 - 14500 K. We have studied the possible
contribution of different processes to the broad He I lines present in the sn
stars. Although NLTE effects could not be completely ruled out, it seems that
NLTE is not directly related to the broad He I profiles observed in the sn
stars. The broad-line He I 4026 is the clearest example of the sn
characteristics in our sample. We succesfully fit this line in 4 out of 7 sn
stars by using the appropriate Stark broadening tables, while small differences
appear in the other 3 stars. Studying the plots of abundance vs depth for the
He I lines resulted in some sn stars probably being stratified in He. However,
a further study of variability in the He I lines would help for determining
whether a possible non-uniform He superficial distribution could also play a
role in these sn stars. We conclude that the broad He I lines that characterize
the sn class could be modelled (at least in some of these stars) by the usual
radiative transfer process with Stark broadening, without needing another
broadening mechanism. The observed line broadening in sn stars seems to be
related to the "normal" He line formation that originates in these atmospheres.
(abridged)


title:
Beyond the constant-mass Dirac physics: Solitons, charge
  fractionization, and the emergence of topological insulators in graphene
  rings

abstract:
  The doubly-connected polygonal geometry of planar graphene rings is found to
bring forth topological configurations for accessing nontrivial relativistic
quantum field (RQF) theory models that carry beyond the constant-mass
Dirac-fermion theory. These include generation of sign-alternating masses,
solitonic excitations, and charge fractionization. The work integrates a RQF
Lagrangian formulation with numerical tight-binding Aharonov-Bohm electronic
spectra and the generalized position-dependent-mass Dirac equation. In contrast
to armchair graphene rings (aGRGs) with pure metallic arms, certain classes of
aGRGs with semiconducting arms, as well as with mixed metallic-semiconducting
ones, are shown to exhibit properties of one-dimensional nontrivial topological
insulators. This further reveals an alternative direction for realizing a
graphene-based nontrivial topological insulator through the manipulation of the
honeycomb lattice geometry, without a spin-orbit contribution.


title: On matrix balancing and eigenvector computation

abstract:
  Balancing a matrix is a preprocessing step while solving the nonsymmetric
eigenvalue problem. Balancing a matrix reduces the norm of the matrix and
hopefully this will improve the accuracy of the computation. Experiments have
shown that balancing can improve the accuracy of the computed eigenval- ues.
However, there exists examples where balancing increases the eigenvalue
condition number (potential loss in accuracy), deteriorates eigenvector
accuracy, and deteriorates the backward error of the eigenvalue decomposition.
In this paper we propose a change to the stopping criteria of the LAPACK
balancing al- gorithm, GEBAL. The new stopping criteria is better at
determining when a matrix is nearly balanced. Our experiments show that the new
algorithm is able to maintain good backward error, while improving the
eigenvalue accuracy when possible. We present stability analysis, numerical
experiments, and a case study to demonstrate the benefit of the new stopping
criteria.


title:
A refined analysis of the Poisson channel in the high-photon-efficiency
  regime

abstract:
  We study the discrete-time Poisson channel under the constraint that its
average input power (in photons per channel use) must not exceed some constant
E. We consider the wideband, high-photon-efficiency extreme where E approaches
zero, and where the channel's "dark current" approaches zero proportionally
with E. Improving over a previously obtained first-order capacity
approximation, we derive a refined approximation, which includes the exact
characterization of the second-order term, as well as an asymptotic
characterization of the third-order term with respect to the dark current. We
also show that pulse-position modulation is nearly optimal in this regime.


title: Viscous Dark Energy and Phantom Field in An Anisotropic Universe

abstract:
  In this paper we have investigated the general form of viscous and
non-viscous dark energy equation of state (EoS) parameter in the scope of
anisotropic Bianchi type I space-time. We show that the presence of bulk
viscosity causes transition of $\omega^{de}$ from quintessence to phantom but
the phantom state is an unstable state (as expected) and EoS of DE tends to
$-1$ at late time. Then we show this phantomic description of the viscous dark
energy and reconstruct the potential of the phantom scalar field. It is found
that bulk viscosity pushes the universe to a darker region. We have also shown
that at late time $q\sim-\Omega^{de}$.


title: A geometric version of the Andrasfai-Erdos-Sos theorem

abstract:
  For each odd integer $k\ge 5$, we prove that, if $M$ is a simple rank-$r$
binary matroid with no odd circuit of length less than $k$ and with $|M| > k
2^{r-k+1}$, then $M$ is isomorphic to a restriction of the rank-$r$ binary
affine geometry; this bound is tight for all $r\ge k-1$. We use this to give a
simpler proof of the following result of Govaerts and Storme: for each integer
$n\ge 2$, if $M$ is a simple rank-$r$ binary matroid with no
$PG(n-1,2)$-restriction and with $|M| > \left(1-\frac{11}{2^{n+2}}\right) 2^r$,
then $M$ has critical number at most $n-1$. That result is a geometric analogue
of a theorem of Andrasfai, Erdos, and Sos in extremal graph theory.


title: Noncommutative Cross-Ratios

abstract:
  We present a definition of and discuss basic properties of cross-ratios over
noncommutative skew-fields. A new theorem was added.


title: Local topological algebraicity of analytic function germs

abstract:
  T. Mostowski showed that every (real or complex) germ of an analytic set is
homeomorphic to the germ of an algebraic set. In this paper we show that every
(real or complex) analytic function germ, defined on a possibly singular
analytic space, is topologically equivalent to a polynomial function germ
defined on an affine algebraic variety.


title:
Effective Bounds of Linear Series on Algebraic Varieties and Arithmetic
  Varieties

abstract:
  In this paper, we prove effective upper bounds for effective sections of line
bundles on projective varieties and hermitian line bundles on arithmetic
varieties in terms of the volumes. They are effective versions of the
Hilbert--Samuel formula and the arithmetic Hilbert--Samuel formula.


title: Ghosts in Keldysh-Schwinger Formalism

abstract:
  We discuss how to introduce Faddeev-Popov ghosts to the Keldysh-Schwinger
formalism describing equilibrium and non-equilibrium statistical systems of
quantum fields such as the quark-gluon plasma which is considered. The plasma
is assumed to be homogeneous in a coordinate space but the momentum
distribution of plasma constituents is arbitrary. Using the technique of
generating functional, we derive the Slavnov-Taylor identities and one of them
expresses the ghost Green's function, which we look for, through the gluon one.
As an application, the Green's function of ghosts is used to compute the gluon
polarization tensor in the hard loop approximation which appears to be
automatically transverse, as required by the gauge invariance.


title: Stably Cayley semisimple groups

abstract:
  A linear algebraic group G over a field k is called a Cayley group if it
admits a Cayley map, i.e. a G-equivariant birational isomorphism over k between
the group variety G and its Lie algebra Lie(G). A prototypical example is the
classical "Cayley transform" for the special orthogonal group SO(n) defined by
Arthur Cayley in 1846. A linear algebraic k-group G is called stably Cayley if
$G \times S$ is Cayley for some split k-torus S. We classify stably Cayley
semisimple groups over an arbitrary field k of characteristic 0.


title:
Trusty URIs: Verifiable, Immutable, and Permanent Digital Artifacts for
  Linked Data

abstract:
  To make digital resources on the web verifiable, immutable, and permanent, we
propose a technique to include cryptographic hash values in URIs. We call them
trusty URIs and we show how they can be used for approaches like
nanopublications to make not only specific resources but their entire reference
trees verifiable. Digital artifacts can be identified not only on the byte
level but on more abstract levels such as RDF graphs, which means that
resources keep their hash values even when presented in a different format. Our
approach sticks to the core principles of the web, namely openness and
decentralized architecture, is fully compatible with existing standards and
protocols, and can therefore be used right away. Evaluation of our reference
implementations shows that these desired properties are indeed accomplished by
our approach, and that it remains practical even for very large files.


title: Spontaneous, collective coherence in driven, dissipative cavity arrays

abstract:
  We study an array of dissipative tunnel-coupled cavities, each interacting
with an incoherently pumped two-level emitter. For cavities in the lasing
regime, we find correlations between the light fields of distant cavities,
despite the dissipation and the incoherent nature of the pumping mechanism.
These correlations decay exponentially with distance for arrays in any
dimension but become increasingly long ranged with increasing photon tunneling
between adjacent cavities. The interaction-dominated and the
tunneling-dominated regimes show markedly different scaling of the correlation
length which always remains finite due to the finite photon trapping time. We
propose a series of observables to characterize the spontaneous build-up of
collective coherence in the system.


title: General inverse problems for regular variation

abstract:
  Regular variation of distributional tails is known to be preserved by various
linear transformations of some random structures. An inverse problem for
regular variation aims at understanding whether the regular variation of a
transformed random object is caused by regular variation of components of the
original random structure. In this paper we build up on previous work and
derive results in the multivariate case and in situations where regular
variation is not restricted to one particular direction or quadrant.


title:
Gromov--Witten theory of Fano orbifold curves, Gamma integral structures
  and ADE-Toda Hierarchies

abstract:
  We construct an integrable hierarchy in the form of Hirota quadratic
equations (HQE) that governs the Gromov--Witten (GW) invariants of the Fano
orbifold projective curve $\mathbb{P}^1_{a_1,a_2,a_3}$. The vertex operators in
our construction are given in terms of the $K$-theory of
$\mathbb{P}^1_{a_1,a_2,a_3}$ via Iritani's $\Gamma$-class modification of the
Chern character map. We also identify our HQEs with an appropriate
Kac--Wakimoto hierarchy of ADE type. In particular, we obtain a generalization
of the famous Toda conjecture about the GW invariants of $\mathbb{P}^1$ .

categories: math.AG math-ph math.MP math.QA math.RT math.SG


title:
Ionization by Massive Young Clusters as Revealed by Ionization-Parameter
  Mapping

abstract:
  Ionization-parameter mapping (IPM) is a powerful technique for tracing the
optical depth of Lyman continuum radiation from massive stars. Using
narrow-band line-ratio maps, we examine trends in radiative feedback from
ordinary HII regions of the Magellanic Clouds and nearby starburst galaxies. We
find that the aggregate escape fraction for the Lyman continuum is sufficient
to ionize the diffuse, warm ionized medium in the Magellanic Clouds, and that
more luminous nebulae are more likely to be optically thin. We apply
ionization-parameter mapping to entire starburst galaxies, revealing ionization
cones in two nearby starbursts. Within the limits of our small sample, we
examine the conditions for the propagation of ionizing radiation beyond the
host galaxies.


title: Quantum Hamiltonian identification from measurement time traces

abstract:
  Precise identification of parameters governing quantum processes is a
critical task for quantum information and communication technologies. In this
work we consider a setting where system evolution is determined by a
parameterized Hamiltonian, and the task is to estimate these parameters from
temporal records of a restricted set of system observables (time traces). Based
on the notion of system realization from linear systems theory we develop a
constructive algorithm that provides estimates of the unknown parameters
directly from these time traces. We illustrate the algorithm and its robustness
to measurement noise by applying it to a one-dimensional spin chain model with
variable couplings.


title: Partition Expanders

abstract:
  We introduce a new concept, which we call partition expanders. The basic idea
is to study quantitative properties of graphs in a slightly different way than
it is in the standard definition of expanders. While in the definition of
expanders it is required that the number of edges between any pair of
sufficiently large sets is close to the expected number, we consider partitions
and require this condition only for most of the pairs of blocks. As a result,
the blocks can be substantially smaller.
  We show that for some range of parameters, to be a partition expander a
random graph needs exponentially smaller degree than any expander would require
in order to achieve similar expanding properties.
  We apply the concept of partition expanders in communication complexity.
First, we give a PRG for the SMP model of the optimal seed length, n+O(log k).
Second, we compare the model of SMP to that of Simultaneous Two-Way
Communication, and give a new separation that is stronger both qualitatively
and quantitatively than the previously known ones.


title:
An efficient space-time adaptive wavelet Galerkin method for
  time-periodic parabolic partial differential equations

abstract:
  We introduce a multitree-based adaptive wavelet Galerkin algorithm {for}
space-time discretized linear parabolic partial differential equations,
focusing on time-periodic problems. It is shown that the method converges with
the best possible rate in linear complexity and can be applied for a wide range
of wavelet bases. We discuss the implementational challenges arising from the
Petrov-Galerkin nature of the variational formulation and present numerical
results for the heat and a convection-diffusion-reaction equation.


title:
Random-field Solutions to Linear Hyperbolic Stochastic Partial
  Differential Equations with Variable Coefficients

abstract:
  In this article we show the existence of a random-field solution to linear
stochastic partial differential equations whose partial differential operator
is hyperbolic and has variable coefficients that may depend on the temporal and
spatial argument. The main tools for this, pseudo-differential and Fourier
integral operators, come from microlocal analysis. The equations that we treat
are second-order and higher-order strictly hyperbolic, and second-order weakly
hyperbolic with uniformly bounded coefficients in space. For the latter one we
show that a stronger assumption on the correlation measure of the random noise
might be needed. Moreover, we show that the well-known case of the stochastic
wave equation can be embedded into the theory presented in this article.


title: Binding of He$_n$V Clusters to $\alpha$-Fe Grain Boundaries

abstract:
  The objective of this research is to explore the formation/binding energetics
and length scales associated with the interaction between He$_n$V clusters and
grain boundaries in bcc $\alpha$-Fe. In this work, we calculated
formation/binding energies for 1-8 He atoms in a monovacancy at all potential
grain boundary sites within 15 \AA\ of the ten grain boundaries selected
(122106 simulations total). The present results provide detailed information
about the interaction energies and length scales of 1--8 He atoms with grain
boundaries for the structures examined. A number of interesting new findings
emerge from the present study. First, the $\Sigma3$(112) `twin' GB has
significantly lower binding energies for all He$_n$V clusters than all other
boundaries in this study. For all grain boundary sites, the effect of the local
environment surrounding each site on the He$_n$V formation and binding energies
decreases with an increasing number of He atoms in the He$_n$V cluster. Based
on the calculated dataset, we formulated a model to capture the evolution of
the formation and binding energy of He$_n$V clusters as a function of distance
from the GB center, utilizing only constants related to the maximum binding
energy and the length scale.


title:
Measurement of differential $t\bar{t}$ production cross sections in
  $p\bar{p}$ collisions

abstract:
  The production of top quark-antiquark pair events in $p\bar{p}$ collisions at
$\sqrt{s}=1.96$ TeV is studied as a function of the transverse momentum and
absolute value of the rapidity of the top quarks as well as of the invariant
mass of the $t\bar{t}$ pair. We select events containing an isolated lepton, a
large imbalance in transverse momentum, and four or more jets with at least one
jet identified to originate from a $b$ quark. The data sample corresponds to
9.7 fb$^{-1}$ of integrated luminosity recorded with the D0 detector during Run
II of the Fermilab Tevatron Collider. Observed differential cross sections are
consistent with standard model predictions.


title: Interaction of graphene monolayer with ultrashort laser pulse

abstract:
  We study the interaction of graphene with ultrashort few femtosecond long
optical pulse. For such a short pulse, the electron dynamics is coherent and is
described within the tight-binding model of graphene. The interaction of
optical pulse with graphene is determined by strong wave vector dependence of
the interband dipole matrix elements, which are singular at the Dirac points of
graphene. The electron dynamics in optical pulse is highly irreversible with
large residual population of the conduction band. The residual conduction band
population as a function of the wave vector is nonuniform with a few localized
spots of high conduction band population. The spots are located near the Dirac
points and the number of spots depends on the pulse intensity. The optical
pulse propagating through graphene layer generates finite transferred charge,
which, as a function of pulse intensity, changes its sign. At small pulse
intensity, the charge is transferred in the direction of the pulse maximum,
while at large pulse intensity, the direction of the charge transfer is
opposite to the direction of pulse maximum. This property opens unique
possibility of controlling the direction of the charge transfer by variation of
the pulse intensity.


title: Orthogonal Matrix in Cryptography

abstract:
  In this work is proposed a method using orthogonal matrix transform
properties to encrypt and decrypt a message. It will be showed how to use
matrix functions to create complex encryptions. Because orthogonal matrix are
always diagonalizable on R, and the exponential of a diagonal matrix is easy to
compute, the exponential of orthogonal matrix will be used to encrypt text
messages.


title: Quenching of Highly-Rotationally-Excited HCl in Collisions with HE

abstract:
  We report rotational quenching cross sections and rate coefficients of HCl
due to collisions with He. The close-coupling method and the coupled-states
approximation are applied in quantum-mechanical scattering calculations of
state-to-state cross sections for HCl with initial rotational levels up to
$j=20$ for kinetic energies from 10$^{-5}$ to 15000 cm$^{-1}$. State-to-state
rate coefficients for temperature between 0.1 and 3000 K are also presented.
Comparison of the present rate coefficients with previous results reported in
the literature for lowly-excited rotational levels shows reasonable agreement.
Small differences are attributed to the differences in the interaction
potential energy surfaces. The uncertainty in the computed cross sections and
rate coefficients is estimated by varying the potential well depth.
Applications of current results to astrophysical systems are also briefly
discussed.


title:
Reaserchnig the Development of the Electrical Power System Using
  Systemically Evolutionary Algorithm

abstract:
  The paper contains the concept and the results of research concerning the
evolutionary algorithm, identified based on the systems control theory, which
was called the Systemically of Evolutionary Algorithm (SAE). Special attention
was paid to two elements of evolutionary algorithms, which have not been fully
solved yet, i.e. to the methods used to create the initial population and the
method of creating the robustness (fitness) function. Other elements of the SEA
algorithm, i.a. cross-over, mutation, selection, etc. were also defined from a
systemic point of view. Computational experiments were conducted using a
selected subsystem of the Polish Electrical Power System and three programming
languages: Java, C++ and Matlab. Selected comparative results for the SAE
algorithm in different implementations were also presented.


title:
The Nature of the Controversy over Time-Symmetric Quantum
  Counterfactuals

abstract:
  It is proposed that the recent controversy over "time-symmetric quantum
counterfactuals" (TSQCs), based on the Aharonov-Bergmann-Lebowitz Rule for
measurements of pre- and post-selected systems, can be clarified by taking
TSQCs to be counterfactuals with a specific type of compound antecedent. In
that case, inconsistency proofs such as that of Sharp and Shanks (1993) are not
applicable, and the main issue becomes not whether such statements are true,
but whether they are nontrivial. The latter question is addressed and answered
in the negative. Thus it is concluded that TSQCs, understood as counterfactuals
with a compound antecedent, are true but only trivially so, and provide no new
contingent information about specific quantum systems (except in special cases
already identified in the literature).


title: Advanced Signal Processing Techniqes to Study Normal and Epileptic EEG

abstract:
  EEG monitoring has an important milestone provide valuable information of
those candidates who suffer from epilepsy.In this paper human normal and
epileptic Electroencephalogram signals are analyzed with popular and efficient
signal processing techniques like Fourier and Wavelet transform. The delta,
theta, alpha, beta and gamma sub bands of EEG are obtained and studied for
detection of seizure and epilepsy. The extracted feature is then applied to ANN
for classification of the EEG signals.


title:
Long-term memory in experiments and numerical simulations of
  hydrodynamic and magnetohydrodynamic turbulence

abstract:
  We analyze time series stemming from experiments and direct numerical
simulations of hydrodynamic and magnetohydrodynamic turbulence. Simulations are
done in periodic boxes, but with a volumetric forcing chosen to mimic the
geometry of the flow in the experiments, the von K\'arm\'an swirling flow
between two counter-rotating impellers. Parameters in the simulations are
chosen to (within computational limitations) allow comparisons between the
experiments and the numerical results. Conducting fluids are considered in all
cases. Two different configurations are considered: a case with a weak
externally imposed magnetic field, and a case with self-sustained magnetic
fields. Evidence of long-term memory and $1/f$ noise is observed in experiments
and simulations, in the case with weak magnetic field associated with the
hydrodynamic behavior of the shear layer in the von K\'arm\'an flow, and in the
dynamo case associated with slow magnetohydrodynamic behavior of the large
scale magnetic field.


title:
A thermodynamically consistent phase-field model for two-phase flows
  with thermocapillary effects

abstract:
  In this paper, we develop a phase-field model for binary incompressible
(quasi-incompressible) fluid with thermocapillary effects, which allows for the
different properties (densities, viscosities and heat conductivities) of each
component while maintaining thermodynamic consistency. The governing equations
of the model including the Navier-Stokes equations with additional stress term,
Cahn-Hilliard equations and energy balance equation are derived within a
thermodynamic framework based on entropy generation, which guarantees
thermodynamic consistency. A sharp-interface limit analysis is carried out to
show that the interfacial conditions of the classical sharp-interface models
can be recovered from our phase-field model. Moreover, some numerical examples
including thermocapillary convections in a two-layer fluid system and
thermocapillary migration of a drop are computed using a continuous finite
element method. The results are compared to the corresponding analytical
solutions and the existing numerical results as validations for our model.


title: Benford's Law and the Universe

abstract:
  Benford's law predicts the occurrence of the $n^{\mathrm{th}}$ digit of
numbers in datasets originating from various sources of the world, ranging from
financial data to atomic spectra. It is intriguing that although many features
of Benford's law have been proven and analysed, it is still not fully
mathematically understood. In this paper we investigate the distances of
galaxies and stars by comparing the first, second and third significant digit
probabilities with Benford's predictions. It is found that the distances of
galaxies follow reasonably well the first digit law and the star distances
agree very well with the first, second and third significant digit.


title:
Universal chiral conductivities for low temperature holographic
  superfluids

abstract:
  We argue that the chiral conductivities of generic s-wave holographic
superfluids, whose broken U(1) symmetry is anomalous, exhibit universal
behavior at low temperatures. The universal behavior we argue for is
independent of the details of the bulk action and on the emergent geometry deep
in the bulk interior at low temperatures. Our results are contrasted against
general expectations based on an analysis of the entropy current in
superfluids.


title:
Chemodynamical evolution of the Milky Way disk II: Variations with
  Galactic radius and height above the disk plane

abstract:
  [Abridge] In the first paper of this series (paper I) we presented a new
approach for studying the chemo-odynamical evolution in disk galaxies, focusing
on the Milky Way. Here we extend these results to different distances from the
Galactic center, looking for variations of observables that can be related to
on-going and future spectroscopic surveys. By separating the effects of
kinematic heating and radial migration, we show that migration is much more
important, even for the oldest and hottest stellar population. The
distributions of stellar birth guiding radii and final guiding radii
(signifying contamination from migration and heating, respectively) widen with
increasing distance from the Galactic center. As a result, the slope in the
age-metallicity relation flattens significantly at Galactic radii larger than
solar. The radial metallicity and [Mg/Fe] gradients in our model show
significant variations with height above the plane due to changes in the
mixture of stellar ages. An inversion in the radial metallicity gradient is
found from negative to weakly positive (at r<10 kpc), and from positive to
negative for the [Mg/Fe] gradient, with increasing distance from the disk
plane. We relate this to the combined effect of (i) the predominance of young
stars close to the disk plane and old stars away from it, (ii) the more
concentrated older stellar component, and (iii) the flaring of mono-age disk
populations. We also investigate the effect of recycled gas flows on the mean
[Fe/H] and find that in the region 4<r<12 kpc the introduced errors are less
than 0.05-0.1 dex, related to the fact that inward and outward flows mostly
cancel in that radial range. We show that radial migration cannot compete with
the inside-out formation of the disk, exposed by the more centrally
concentrated older disk populations, and consistent with recent observations.


title:
A new fitting-function to describe the time evolution of a galaxy's
  gravitational potential

abstract:
  We present a new simple functional form to model the evolution of a spherical
mass distribution in a cosmological context. Two parameters control the growth
of the system and this is modelled using a redshift dependent exponential for
the scale mass and scale radius. In this new model, systems form inside out and
the mass of a given shell can be made to never decrease, as generally expected.
This feature makes it more suitable for studying the smooth growth of galactic
potentials or cosmological halos than other parametrizations often used in the
literature. This is further confirmed through a comparison to the growth of
dark matter halos in the Aquarius simulations.


title:
Confinement induced interlayer molecules: a route to strong interatomic
  interactions

abstract:
  We study theoretically the interaction between two species of ultracold atoms
confined into two layers of a finite separation, and demonstrate the existence
of new types of confinement-induced interlayer bound and quasi-bound molecules:
these novel exciton-like interlayer molecules appear for both positive and
negative scattering lengths, and exist even for layer separations many times
larger than the interspecies scattering length. The lifetime of the quasi-bound
molecules grows exponentially with increasing layer separation, and they can
therefore be observed in simple shaking experiments, as we demonstrate through
detailed many-body calculations. These quasi-bound molecules can also give rise
to novel interspecies Feshbach resonances, enabling one to control
geometrically the interaction between the two species by changing the layer
separation. Rather counter-intuitively, the species can be made strongly
interacting, by increasing their spatial separation. The separation induced
interlayer resonances provide a powerful tool for the experimental control of
interspecies interactions and enables one to realize novel quantum phases of
multicomponent quantum gases.


title: Where Do Galaxies End?

abstract:
  Our current view of galaxies considers them as systems of stars and gas
embedded in extended halos of dark matter, much of it formed by the infall of
smaller systems at earlier times. The true extent of a galaxy remains poorly
determined, with the virial radius (R_vir) providing a characteristic
separation between collapsed structures in dynamical equilibrium and external
infalling matter. Other physical estimates of the extent of gravitational
influence include the gravitational radius, gas accretion radius, and
"galactopause" arising from outflows that stall at 100-200 kpc over a range of
outflow parameters and confining gas pressures. Physical criteria are proposed
to define bound structures, including a more realistic definition of R_vir (M*,
M_h, z_a) for stellar mass M* and halo mass M_h, half of which formed at
"assembly redshifts" z_a = 0.7-1.3. We estimate the extent of bound gas and
dark matter around L* galaxies to be ~200 kpc. The new virial radii, with mean
R_vir ~ 200 kpc, are 40-50% smaller than values estimated in recent HST/COS
detections of H I and O VI absorbers around galaxies. In the new formalism, the
Milky Way stellar mass, log M* = 10.7 +/- 0.1, would correspond to R_vir = 153
(+25,-16) kpc for half-mass halo assembly at z_a = 1.06 +/- 0.03. The frequency
per unit redshift of low-redshift O VI absorption lines in QSO spectra suggests
absorber sizes ~150 kpc when related to intervening 0.1L* galaxies. This
formalism is intended to clarify semantic differences arising from observations
of extended gas in galactic halos, circumgalactic medium (CGM), and filaments
of the intergalactic medium (IGM). Astronomers should refer to bound gas in the
galactic halo or CGM, and unbound gas at the CGM-IGM interface, on its way into
the IGM.


title:
CLASH-VLT: Constraints on the Dark Matter Equation of State from
  Accurate Measurements of Galaxy Cluster Mass Profiles

abstract:
  A pressureless scenario for the Dark Matter (DM) fluid is a widely adopted
hypothesis, despite the absence of a direct observational evidence. According
to general relativity, the total mass-energy content of a system shapes the
gravitational potential well, but different test particles perceive this
potential in different ways depending on their properties. Cluster galaxy
velocities, being $\ll$c, depend solely on the gravitational potential, whereas
photon trajectories reflect the contributions from the gravitational potential
plus a relativistic-pressure term that depends on the cluster mass. We exploit
this phenomenon to constrain the Equation of State (EoS) parameter of the
fluid, primarily DM, contained in galaxy clusters. We use the complementary
information provided by the kinematic and lensing mass profiles of the galaxy
cluster MACS 1206.2-0847 at $z=0.44$, as obtained in an extensive imaging and
spectroscopic campaign within the CLASH survey. The unprecedented high quality
of our data-set and the properties of this cluster are well suited to determine
the EoS parameter of the cluster fluid. Since baryons contribute at most $15\%$
to the total mass in clusters and their pressure is negligible, the EoS
parameter we derive describes the behavior of the DM fluid. We obtain the most
stringent constraint on the DM EoS parameter to date,
$w=(p_r+2\,p_t)/(3\,c^2\rho)=0.00\pm0.15\mathrm{(stat)}\pm0.08\mathrm{(syst)}$,
averaged over the radial range $0.5\,\mathrm{Mpc}\leq$$r$$\leq$$r_{200}$, where
$p_r$ and $p_t$ are the radial and tangential pressure, and $\rho$ is the
density. We plan to further improve our constraint by applying the same
procedure to all clusters from the ongoing CLASH-VLT program.


title:
A Signature of Chromospheric Activity in Brown Dwarfs Revealed by
  2.5-5.0 Micron AKARI Spectra

abstract:
  We propose that the 2.7 micron H_2O, 3.3 micron CH_4 and 4.6 micron CO
absorption bands can be good tracers of chromospheric activity in brown dwarfs.
In our previous study, we found that there are difficulties in explaining
entire spectra between 1.0 and 5.0 microns with the Unified Cloudy Model (UCM),
a brown dwarf atmosphere model. Based on simple radiative equilibrium,
temperature in a model atmosphere usually decreases monotonically with height.
However, if a brown dwarf has a chromosphere, as inferred by some observations,
the temperature in the upper atmosphere is higher. We construct a simple model
that takes into account heating due to chromospheric activity by setting a
temperature floor in an upper atmosphere, and find that the model spectra of 3
brown dwarfs with moderate H-alpha emission, an indicator of chromospheric
activity, are considerably improved to match the AKARI spectra. Because of the
higher temperatures in the upper atmospheres, the amount of CH_4 molecules is
reduced and the absorption band strengths become weaker. The strengths of the
absorption bands of H_2O and CO also become weaker. On the other hand, other
objects with weak H-alpha emission cannot be fitted by our treatment. We also
briefly discuss magnetic heating processes which possibly operate in upper
atmospheres, by extending our numerical simulations for the Sun and stars with
surface convection to brown dwarf atmospheres.


title:
Phase transitions and anomalous normal state in superconductors with
  broken time reversal symmetry

abstract:
  Using Monte Carlo simulations, we explore the phase diagram and the phase
transitions in $\groupUZ$ $n$-band superconductors with spontaneously broken
time-reversal symmetry (also termed $s+is$ superconductors), focusing on the
three-band case. In the limit of infinite penetration length, the system under
consideration can, for a certain parameter regime, have a single first order
phase transition from a $\groupUZ$ broken state to a normal state due to a
nontrivial interplay between $\groupU$ vortices and $\groupZ$ domain walls.
This regime may also apply to multicomponent superfluids. For other parameters,
when the free energy of the domain walls is low, the system undergoes a
restoration of broken $\groupZ$ time reversal symmetry at temperatures lower
than the temperature of the superconducting phase transition.{We show that
inclusion of fluctuations can strongly suppress the temperature of the
$\groupZ$-transition when frustration is weak. The main result of our paper is
that} for relatively short magnetic field penetration lengths, the system has a
superconducting phase transition at a temperature lower than the temperature of
the restoration of the broken $\groupZ$ symmetry. Thus, there appears a new
phase which is $\groupU$-symmetric, but breaks $\groupZ$ time reversal
symmetry, an anomalous dissipative (metallic) state.


title:
H_2 Suppression with Shocking Inflows: Testing a Pathway for
  Supermassive Black Hole Formation

abstract:
  The presence of quasars at redshifts z > 6 indicates the existence of
supermassive black holes (SMBHs) as massive as a few times 10^9 Msun,
challenging models for SMBH formation. One pathway is through the direct
collapse of gas in T_{vir} > 10^4 K halos; however, this requires the
suppression of H_2 cooling to prevent fragmentation. In this paper, we examine
a proposed new mechanism for this suppression which relies on cold-mode
accretion flows leading to shocks at high densities (n > 10^4 cm^{-3}) and
temperatures (T > 10^4 K). In such gas, H_2 is efficiently collisionally
dissociated. We use high-resolution numerical simulations to test this idea,
demonstrating that such halos typically have lower temperature progenitors, in
which cooling is efficient. Those halos do show filamentary flows; however, the
gas shocks at or near the virial radius (at low densities), thus preventing the
proposed collisional mechanism from operating. We do find that, if we
artificially suppress H_2 formation with a high UV background, so as to allow
gas in the halo center to enter the high-temperature, high-density "zone of no
return", it will remain there even if the UV flux is turned off, collapsing to
high density at high temperature. Due to computational limitations, we
simulated only three halos. However, we demonstrate, using Monte Carlo
calculations of 10^6 halo merger histories, that a few rare halos could
assemble rapidly enough to avoid efficient H_2 cooling in all of their
progenitor halos, provided that the UV background exceeds J_{21} ~ few at
redshifts as high as z ~ 20.


title:
Modulated Hawking radiation and a nonviolent channel for information
  release

abstract:
  Unitarization of black hole evaporation requires that quantum information
escapes a black hole; an important question is to identify the mechanism or
channel by which it does so. Accurate counting of black hole states via the
Bekenstein-Hawking entropy would indicate this information should be encoded in
radiation with average energy flux matching Hawking's. Information can be
encoded with no change in net flux via fine-grained modulation of the Hawking
radiation. In an approximate effective field theory description, couplings to
the stress tensor of the black hole atmosphere that depend on the internal
state of the black hole are a promising alternative for inducing such
modulation. These can be picturesquely thought of as due to state-dependent
metric fluctuations in the vicinity of the horizon. Such couplings offer the
prospect of emitting information without extra energy flux, and can be shown to
do so at linear order in the couplings, with motivation given for possible
extension of this result to higher orders. The potential advantages of such
couplings to the stress tensor thus extend beyond their universality, which is
helpful in addressing constraints from black hole mining.


title:
Transmission channels for light in absorbing random media: from
  diffusive to ballistic-like transport

abstract:
  While the absorption of light is ubiquitous in nature and in applications,
the question remains how absorption modifies the transmission channels in
random media. We present a numerical study on the effects of optical absorption
on the maximal transmission and minimal reflection channels in a
two-dimensional disordered waveguide. In the weak absorption regime, where the
system length is less than the diffusive absorption length, the maximal
transmission channel is dominated by diffusive transport and it is equivalent
to the minimal reflection channel. Its frequency bandwidth is determined by the
underlying quasimode width. However, when the absorption is strong, light
transport in the maximal transmission channel undergoes a sharp transition and
becomes ballistic-like transport. Its frequency bandwidth increases with
absorption, and the exact scaling varies with the sample's realization. The
minimal reflection channel becomes different from the maximal transmission
channel and becomes dominated by absorption. Counterintuitively, we observe in
some samples that the minimum reflection eigenvalue increases with absorption.
Our results show that strong absorption turns open channels in random media
from diffusive to ballistic-like.


title: Superconducting Spintronics with Magnetic Domain Walls

abstract:
  The recent experimental demonstration of spin-polarized supercurrents offer a
venue for establishment of a superconducting analogue to conventional
spintronics. Whereas domain wall motion in purely magnetic structures is a
well-studied topic, it is not clear how domain wall dynamics may influence
superconductivity and if some functional property can be harnessed from such a
scenario. Here, we demonstrate that domain wall motion in superconducting
systems offers a unique way of controlling the quantum state of the
superconductor. Considering both the diffusive and ballistic limits, we show
that moving the domain wall to different locations in a Josephson junction will
change the quantum ground state from being in a 0 state to a $\pi$ state.
Remarkably, we also show that domain wall motion can be used to turn on and off
superconductivity: the position of the domain wall determines the critical
temperature $T_c$ and thus if the system is in a resistive state or not,
causing even a quantum phase transition between the dissipationless and normal
state at $T=0$. In this way, one achieves dynamical control over the
superconducting state within a single sample by utilizing magnetic domain wall
motion.


title: Constraining multi-Higgs flavour models

abstract:
  To study a flavour model with a non-minimal Higgs sector one must first
define the symmetries of the fields; then identify what types of vacua exist
and how they may break the symmetries; and finally determine whether the
remnant symmetries are compatible with the experimental data. Here we address
all these issues in the context of flavour models with any number of Higgs
doublets. We stress the importance of analysing the Higgs vacuum expectation
values that are pseudo-invariant under the generators of all subgroups. It is
shown that the only way of obtaining a physical CKM mixing matrix and,
simultaneously, non-degenerate and non-zero quark masses is requiring the
vacuum expectation values of the Higgs fields to break completely the full
flavour group, except possibly for some symmetry belonging to baryon number.
The application of this technique to some illustrative examples, such as the
flavour groups Delta(27), A4 and S3, is also presented.


title:
Reducing the Computational Cost in Multi-objective Evolutionary
  Algorithms by Filtering Worthless Individuals

abstract:
  The large number of exact fitness function evaluations makes evolutionary
algorithms to have computational cost. In some real-world problems, reducing
number of these evaluations is much more valuable even by increasing
computational complexity and spending more time. To fulfill this target, we
introduce an effective factor, in spite of applied factor in Adaptive Fuzzy
Fitness Granulation with Non-dominated Sorting Genetic Algorithm-II, to filter
out worthless individuals more precisely. Our proposed approach is compared
with respect to Adaptive Fuzzy Fitness Granulation with Non-dominated Sorting
Genetic Algorithm-II, using the Hyper volume and the Inverted Generational
Distance performance measures. The proposed method is applied to 1 traditional
and 1 state-of-the-art benchmarks with considering 3 different dimensions. From
an average performance view, the results indicate that although decreasing the
number of fitness evaluations leads to have performance reduction but it is not
tangible compared to what we gain.


title:
Topological Phases in Triangular Lattices of Ru Adsorbed on Graphene:
  ab-initio calculations

abstract:
  We have performed an ab initio investigation of the electronic properties of
the graphene sheet adsorbed by Ru adatoms (Ru/graphene). For a particular set
of triangular arrays of Ru adatoms, we find the formation of four
(spin-polarized) Dirac cones attributed to a suitable overlap between two
hexagonal lattices: one composed by the C sites of the graphene sheet, and the
other formed by the surface potential induced by the Ru adatoms. Upon the
presence of spin-orbit coupling (SOC) nontrivial band gaps take place at the
Dirac cones promoting several topological phases. Depending on the Ru
concentration, the system can be topologically characterized among the phases
i) Quantum Spin Hall (QSH), ii) Quantum Anomalous Hall (QAH), iii) metal iv) or
trivial insulator. For each concentration, the topological phase is
characterized by the ab-initio calculation of the Chern number.


title: Growth and Shape of a Chain Fountain

abstract:
  If a long chain is held in a pot elevated a distance h_1 above the floor, and
the end of the chain is then dragged over the rim of the pot and released, the
chain flows under gravity down into a pile on the floor. Not only does the
chain flow out of the pot, it also leaps above the pot in a "chain-fountain". I
predict and observe that if the pot is held at an angle to the vertical the
steady state shape of the fountain is an inverted catenary, and discuss how to
apply boundary conditions to this solution. In the case of a level pot, the
fountain shape is completely vertical. In this case I predict and observe both
how fast the fountain grows to its steady state hight, and how it grows
quadratically in time if there is no floor. The fountain is driven by an
anomalous push force from the pot that acts on the link of chain about to come
into motion. I confirm this by designing two new chains, one consisting of
hollow cylinders threaded on a string and one consisting of heavy beads
separated by long flexible threads. The former is predicted to produce a
pot-push and hence a fountain, while the latter will not. I confirm these
predictions experimentally. Finally I directly observe the anomalous push in a
horizontal chain-pick up experiment.


title:
Extreme Ultraviolet Late-Phase Flares: Before and During the Solar
  Dynamics Observatory Mission

abstract:
  The SDO EUV observations have revealed interesting characteristics of warm
coronal emissions, which peak soon after the hot coronal X-ray emissions peak
during a flare and then sometimes peak for a second time hours after the X-ray
flare peak. This flare type, with two warm coronal emission peaks but only one
X-ray peak, has been named the EUV late phase. These flares have the distinct
properties of i) having a complex magnetic field structure with two initial
sets of coronal loops, with one upper set overlaying a lower set, ii) having an
eruptive flare initiated in the lower set and disturbing both loop sets, iii)
having the hot coronal emissions emitted only from the lower set, and iv)
having the first peak of the warm coronal emissions associated with the lower
set and its second peak emitted from the upper set much later. The disturbance
of the coronal loops by the eruption is at about the same time, but the
relaxation and cooling down of the heated coronal loops during the post-flare
reconnections have different time scales with the longer, upper loops being
significantly delayed from the lower loops. The difference in these cooling
time scales is related to the difference between the two peak times of the warm
coronal emission and is also apparent in the decay profile of the X-ray
emissions having two distinct decays, with the first decay slope being steeper
and the delayed decay slope being smaller during the time of the warm coronal
emission second peak. The frequency and relationship of the EUV late-phase
decay times between the Fe XVI two flare peaks and X-ray decay slopes are
examined using three years of SDO/EVE data, and the X-ray dual-decay character
is then exploited to estimate the frequency of EUV late-phase flares during the
past four solar cycles. This study indicates that the frequency of EUV
late-phase flares peaks before and after each solar cycle minimum.


title: Faulting of rocks at three-dimensional stress field by micro-anticracks

abstract:
  Using 9-sets of different laboratory earthquake tests, we examined the nature
of cracking under true triaxial stress conditions in the lithosphere . We found
that 3D stress state can induce oblique nucleation of many fractures, forming
final plane of complex polymodal faults. Our fully 3D experiments indicate
unconventional fault nucleation with 2-3 times faster slip phase, implying a
new slip-weakening mechanism for earthquakes in upper crust. In addition, We
compared our observations of irregular cracks with typical anti-cracks signals
in multi-anvil High Pressure and Temperature test. For the first time, we
showed oblique faulting can change slip-weakening rate and accelerate the rate
of energy release. This implicates a sharper source time function for further
modeling of our experiments. Indeed, our results can be assumed as an ex
tension to detachment fronts in micro-faults to a general concept of quasi-anti
rupture fronts. We showed events from deep-focus earthquakes can share some
similarity to shallow earthquakes, promoting recent approach on similarity of
deep earthquakes to their shallow counterparts .


title: GGP with Advanced Reasoning and Board Knowledge Discovery

abstract:
  Quality of General Game Playing (GGP) matches suffers from slow
state-switching and weak knowledge modules. Instantiation and Propositional
Networks offer great performance gains over Prolog-based reasoning, but do not
scale well. In this publication mGDL, a variant of GDL stripped of function
constants, has been defined as a basis for simple reasoning machines. mGDL
allows to easily map rules to C++ functions. 253 out of 270 tested GDL rule
sheets conformed to mGDL without any modifications; the rest required minor
changes. A revised (m)GDL to C++ translation scheme has been reevaluated; it
brought gains ranging from 28% to 7300% over YAP Prolog, managing to compile
even demanding rule sheets under few seconds. For strengthening game knowledge,
spatial features inspired by similar successful techniques from computer Go
have been proposed. For they required an Euclidean metric, a small board
extension to GDL has been defined through a set of ground atomic sentences. An
SGA-based genetic algorithm has been designed for tweaking game parameters and
conducting self-plays, so the features could be mined from meaningful game
records. The approach has been tested on a small cluster, giving performance
gains up to 20% more wins against the baseline UCT player. Implementations of
proposed ideas constitutes the core of GGP Spatium - a small C++/Python GGP
framework, created for developing compact GGP Players and problem solvers.


title: On Randomly Projected Hierarchical Clustering with Guarantees

abstract:
  Hierarchical clustering (HC) algorithms are generally limited to small data
instances due to their runtime costs. Here we mitigate this shortcoming and
explore fast HC algorithms based on random projections for single (SLC) and
average (ALC) linkage clustering as well as for the minimum spanning tree
problem (MST). We present a thorough adaptive analysis of our algorithms that
improve prior work from $O(N^2)$ by up to a factor of $N/(\log N)^2$ for a
dataset of $N$ points in Euclidean space. The algorithms maintain, with
arbitrary high probability, the outcome of hierarchical clustering as well as
the worst-case running-time guarantees. We also present parameter-free
instances of our algorithms.


title: Magnetohydrodynamic Simulations of the Atmosphere of HD 209458b

abstract:
  We present the first three-dimensional magnetohydrodynamic (MHD) simulations
of the atmosphere of HD 209458b which self-consistently include reduction of
winds due to the Lorentz force and Ohmic heating. We find overall wind
structures similar to that seen in previous models of hot Jupiter atmospheres,
with strong equatorial jets and meridional flows poleward near the day side and
equatorward near the night side. Inclusion of magnetic fields slows those winds
and leads to Ohmic dissipation. We find wind slowing ranging from 10%-40% for
reasonable field strengths. We find Ohmic dissipation rates ~10^17 W at 100
bar, orders of magnitude too small to explain the inflated radius of this
planet. Faster wind speeds, not achievable in these anelastic calculations, may
be able to increase this value somewhat, but likely will not be able to close
the gap necessary to explain the inflated radius. We demonstrate that the
discrepancy between the simulations presented here and previous models is due
to inadequate treatment of magnetic field geometry and evolution. Induced
poloidal fields become much larger than those imposed, highlighting the need
for a self-consistent MHD treatment of these hot atmospheres.


title:
Poincar\'e Duality of the basic intersection cohomology of a Killing
  foliation

abstract:
  We prove that the basic intersection cohomology $IH^*_{\overline{p}}(M /
\mathcal{F})$, where $\mathcal{F}$ is the singular foliation determined by an
isometric action of a Lie group $G$ on the compact manifold $M$, verifies the
Poincar\'e Duality Property.


title: Half-Region Depth for Stochastic Processes

abstract:
  We study the concept of half-region depth, introduced by Lopez-Pintado and
Romo in 2011. We show that for a wide variety of standard stochastic processes,
such as Brownian motion and other symmetric stable processes with stationary
independent increments tied down at 0, half-region depth assigns depth zero to
all sample functions. To alleviate this difficulty we introduce a method of
smoothing, which often not only eliminates the problem of zero depth, but
allows us to extend the theoretical results on consistency in that paper up to
the $\sqrt n$ level for many smoothed processes.


title: Neutrino Mixing and Oscillations in Astrophysical Environments

abstract:
  A brief review of the current status of neutrino mixing and oscillations in
astrophysical environments, with particular emphasis on the Sun and
core-collapse supernovae, is given. Implications of the existence of sterile
states which mix with the active neutrinos are discussed.


title:
Asymptotic Analysis of the Ponzano-Regge Model with Non-Commutative
  Metric Boundary Data

abstract:
  We apply the non-commutative Fourier transform for Lie groups to formulate
the non-commutative metric representation of the Ponzano-Regge spin foam model
for 3d quantum gravity. The non-commutative representation allows to express
the amplitudes of the model as a first order phase space path integral, whose
properties we consider. In particular, we study the asymptotic behavior of the
path integral in the semi-classical limit. First, we compare the stationary
phase equations in the classical limit for three different non-commutative
structures corresponding to the symmetric, Duflo and Freidel-Livine-Majid
quantization maps. We find that in order to unambiguously recover discrete
geometric constraints for non-commutative metric boundary data through the
stationary phase method, the deformation structure of the phase space must be
accounted for in the variational calculus. When this is understood, our results
demonstrate that the non-commutative metric representation facilitates a
convenient semi-classical analysis of the Ponzano-Regge model, which yields as
the dominant contribution to the amplitude the cosine of the Regge action in
agreement with previous studies. We also consider the asymptotics of the ${\rm
SU}(2)$ $6j$-symbol using the non-commutative phase space path integral for the
Ponzano-Regge model, and explain the connection of our results to the previous
asymptotic results in terms of coherent states.


title:
Solving the Pricing Problem in a Branch-and-Price Algorithm for Graph
  Coloring using Zero-Suppressed Binary Decision Diagrams

abstract:
  Branch-and-price algorithms combine a branch-and-bound search with an
exponentially-sized LP formulation that must be solved via column generation.
Unfortunately, the standard branching rules used in branch-and-bound for
integer programming interfere with the structure of the column generation
routine; therefore, most such algorithms employ alternate branching rules to
circumvent this difficulty. This paper shows how a zero-suppressed binary
decision diagram (ZDD) can be used to solve the pricing problem in a
branch-and-price algorithm for the graph coloring problem, even in the presence
of constraints imposed by branching decisions. This approach facilitates a much
more direct solution method, and can improve convergence of the column
generation subroutine.


title: Curvaton Dynamics Revisited

abstract:
  We revisit the dynamics of the curvaton in detail taking account of effects
from thermal environment, effective potential and decay/dissipation rate for
general field values and couplings. We also consider the curvature perturbation
generated through combinations of various effects: large scale modulation of
the oscillation epoch, the effective dissipation rate and the timing at which
the equation of state changes. In particular, we find that it tends to be
difficult to explain the observed curvature perturbation by the curvaton
mechanism without producing too large non-Gaussianity if the curvaton energy
density is dissipated through thermal effects. Therefore, the interaction
between the curvaton and light elements in the thermal plasma should be
suppressed in order for the curvaton to survive the thermal dissipation.


title:
Symmetry energy, neutron skin, and neutron star radius from chiral
  effective field theory interactions

abstract:
  We discuss neutron matter calculations based on chiral effective field theory
interactions and their predictions for the symmetry energy, the neutron skin of
208 Pb, and for the radius of neutron stars.


title: Collaborative Regression

abstract:
  We consider the scenario where one observes an outcome variable and sets of
features from multiple assays, all measured on the same set of samples. One
approach that has been proposed for dealing with this type of data is ``sparse
multiple canonical correlation analysis'' (sparse mCCA). All of the current
sparse mCCA techniques are biconvex and thus have no guarantees about reaching
a global optimum. We propose a method for performing sparse supervised
canonical correlation analysis (sparse sCCA), a specific case of sparse mCCA
when one of the datasets is a vector. Our proposal for sparse sCCA is convex
and thus does not face the same difficulties as the other methods. We derive
efficient algorithms for this problem, and illustrate their use on simulated
and real data.


title:
Role of stress-assisted martensite in the design of strong
  ultrafine-grained duplex steels

abstract:
  This work explains the occurrence of transformation-induced plasticity via
stress-assisted martensite, when designing ultrafine-grained duplex steels. It
is found that, when the austenite is reduced to a fine scale of about 300 nm,
the initial deformation-induced microstructure can be dominated by parallel
lamellae of epsilon martensite or mechanical twinning, which cannot efficiently
provide nucleation sites for strain-induced martensite. Hence, alpha martensite
nucleation occurs independently by a stress-assisted process that enhances
transformation-induced plasticity in ultrafine-grained austenite. This
metallurgical principle was validated experimentally by using a combination of
transmission Kikuchi diffraction mapping, transmission electron microscopy, and
atom probe microscopy, and demonstrated theoretically by the thermodynamics
model of stress-assisted martensite.


title: First results of the SDHCAL technological prototype

abstract:
  The CALICE Semi-digital hadronic calorimeter built in 2011, was installed and
tested during two periods of two weeks each in 2012 at CERN SPS facilities. The
detector has more than 450000 channels with a semi-digital readout distributed
on 48 layers with efficiency exceeding 95%. It has been run using the
trigger-less and power pulsing modes. Data have been collected with muon,
electron and hadron beams in the energy range between 5 and 80 GeV. This
contribution focuses on the performances, the shower selection methods and on
the first results on the calibration using pions.


title:
Improving Smartphone Battery Life Utilizing Device-to-device Cooperative
  Relays Underlaying LTE Networks

abstract:
  The utility of smartphones has been limited to a great extent by their short
battery life. In this work, we propose a new approach to prolonging smartphone
battery life. We introduce the notions of "valueless" and "valued battery", as
being the available battery when the user does or does not have access to a
power source, respectively. We propose a cooperative system where users with
high battery level help carry the traffic of users with low battery level. Our
scheme helps increase the amount of valued battery in the network, thus it
reduces the chance of users running out of battery early. Our system can be
realized in the form of a proximity service (ProSe) which utilizes a
device-to-device (D2D) communication architecture underlaying LTE. We show
through simulations that our system reduces the probability of cellular users
running out of battery before their target usage time (probability of outage).
Our simulator source code is made available to the public.


title:
A Bose-condensed, simultaneous dual species Mach-Zehnder atom
  interferometer

abstract:
  This paper presents the first realisation of a simultaneous $^{87}$Rb
-$^{85}$Rb Mach-Zehnder atom interferometer with Bose-condensed atoms. A number
of ambitious proposals for precise terrestrial and space based tests of the
Weak Equivalence Principle rely on such a system. This implementation utilises
hybrid magnetic-optical trapping to produce spatially overlapped condensates
with a duty cycle of 20s. A horizontal optical waveguide with co-linear Bragg
beamsplitters and mirrors is used to simultaneously address both isotopes in
the interferometer. We observe a non-linear phase shift on a non-interacting
$^{85}$Rb interferometer as a function of interferometer time, $T$, which we
show arises from inter-isotope scattering with the co-incident $^{87}$Rb
interferometer. A discussion of implications for future experiments is given.


title: Applications of Information Nonanticipative Rate Distortion Function

abstract:
  The objective of this paper is to further investigate various applications of
information Nonanticipative Rate Distortion Function (NRDF) by discussing two
working examples, the Binary Symmetric Markov Source with parameter $p$
(BSMS($p$)) with Hamming distance distortion, and the multidimensional
partially observed Gaussian-Markov source. For the BSMS($p$), we give the
solution to the NRDF, and we use it to compute the Rate Loss (RL) of causal
codes with respect to noncausal codes. For the multidimensional Gaussian-Markov
source, we give the solution to the NRDF, we show its operational meaning via
joint source-channel matching over a vector of parallel Gaussian channels, and
we compute the RL of causal and zero-delay codes with respect to noncausal
codes.


title: A coordinate free characterization of certain quasidiagonal operators

abstract:
  We obtain (i) a new, coordinate free, characterization of quasidiagonal
operators with essential spectra contained in the unit circle by adapting the
proof of a classical result in the theory of Banach spaces, (ii) an affirmative
answer to some questions of Hadwin, and (iii) an alternative proof of Hadwin's
characterization of the SOT, WOT and $*$-SOT closure of the unitary orbit of a
given operator on a separable, infinite dimensional, complex Hilbert space.


title: A Prediction Model for System Testing Defects using Regression Analysis

abstract:
  This research describes the initial effort of building a prediction model for
defects in system testing carried out by an independent testing team. The
motivation to have such defect prediction model is to serve as early quality
indicator of the software entering system testing and assist the testing team
to manage and control test execution activities. Metrics collected from prior
phases to system testing are identified and analyzed to determine the potential
predictors for building the model. The selected metrics are then put into
regression analysis to generate several mathematical equations. Mathematical
equation that has p-value of less than 0.05 with R-squared and R-squared
(adjusted) more than 90% is selected as the desired prediction model for system
testing defects. This model is verified using new projects to confirm that it
is fit for actual implementation.


title: Retarded Fields of Null Particles and the Memory Effect

abstract:
  We consider the retarded solution to the scalar, electromagnetic, and
linearized gravitational field equations in Minkowski spacetime, with source
given by a particle moving on a null geodesic. In the scalar case and in the
Lorenz gauge in the electromagnetic and gravitational cases, the retarded
integral over the infinite past of the source does not converge as a
distribution, so we cut off the null source suitably at a finite time $t_0$ and
then consider two different limits: (i) the limit as the observation point goes
to null infinity at fixed $t_0$, from which the ``$1/r$'' part of the fields
can be extracted and (ii) the limit $t_0 \to - \infty$ at fixed ``observation
point.'' The limit (i) gives rise to a ``velocity kick'' on distant test
particles in the scalar and electromagnetic cases, and it gives rise to a
``memory effect'' (i.e., a permanent change in relative separation of two test
particles) in the linearized gravitational case, in agreement with previous
analyses. Although the second limit does not exist for the Lorenz gauge
potentials in the electromagnetic and linearized gravitational cases, we obtain
a well defined distributional limit for the electromagnetic field strength and
for the linearized Riemann tensor. In the gravitational case, this limit agrees
with the Aichelberg-Sexl solution, but there is no ``memory effect'' associated
with this limiting solution. This strongly suggests that the memory
effect---including nonlinear memory effect of Christodoulou---should not be
interpreted as arising simply from the passage of (effective) null stress
energy to null infinity but rather as arising from a ``burst of radiation''
associated with the creation of the null stress-energy (as in case (i) above)
or, more generally, with radiation present in the spacetime that was not
``produced'' by the null stress-energy.


title:
Robust Transport Signatures of Topological Superconductivity in
  Topological Insulator Nanowires

abstract:
  Finding a clear signature of topological superconductivity in transport
experiments remains an outstanding challenge. In this work, we propose
exploiting the unique properties of three-dimensional topological insulator
nanowires to generate a normal-superconductor junction in the single-mode
regime where an exactly quantized $2e^2/h$ zero-bias conductance can be
observed over a wide range of realistic system parameters. This is achieved by
inducing superconductivity in half of the wire, which can be tuned at will from
trivial to topological with a parallel magnetic field, while a perpendicular
field is used to gap out the normal part, except for two spatially separated
chiral channels. The combination of chiral mode transport and perfect Andreev
reflection makes the measurement robust to moderate disorder, and the
quantization of conductance survives to much higher temperatures than in tunnel
junction experiments. Our proposal may be understood as a variant of a Majorana
interferometer which is easily realizable in experiments.


title: Multiscale Dictionary Learning: Non-Asymptotic Bounds and Robustness

abstract:
  High-dimensional datasets are well-approximated by low-dimensional
structures. Over the past decade, this empirical observation motivated the
investigation of detection, measurement, and modeling techniques to exploit
these low-dimensional intrinsic structures, yielding numerous implications for
high-dimensional statistics, machine learning, and signal processing. Manifold
learning (where the low-dimensional structure is a manifold) and dictionary
learning (where the low-dimensional structure is the set of sparse linear
combinations of vectors from a finite dictionary) are two prominent theoretical
and computational frameworks in this area. Despite their ostensible
distinction, the recently-introduced Geometric Multi-Resolution Analysis (GMRA)
provides a robust, computationally efficient, multiscale procedure for
simultaneously learning manifolds and dictionaries.
  In this work, we prove non-asymptotic probabilistic bounds on the
approximation error of GMRA for a rich class of data-generating statistical
models that includes "noisy" manifolds, thereby establishing the theoretical
robustness of the procedure and confirming empirical observations. In
particular, if a dataset aggregates near a low-dimensional manifold, our
results show that the approximation error of the GMRA is completely independent
of the ambient dimension. Our work therefore establishes GMRA as a provably
fast algorithm for dictionary learning with approximation and sparsity
guarantees. We include several numerical experiments confirming these
theoretical results, and our theoretical framework provides new tools for
assessing the behavior of manifold learning and dictionary learning procedures
on a large class of interesting models.


title:
Three-dimensional Gaussian fluctuations of non-commutative random
  surfaces along time-like paths

abstract:
  We construct a continuous-time non-commutative random walk on
$U(\mathfrak{gl}_N)$ with dilation maps $U(\mathfrak{gl}_N)\rightarrow
L^2(U(N))^{\otimes\infty}$. This is an analog of a continuous-time
non-commutative random walk on the group von Neumann algebra $vN(U(N))$
constructed in [15], and is a variant of discrete-time non-commutative random
walks on $U(\mathfrak{gl}_N)$ [2,9].
  It is also shown that when restricting to the Gelfand-Tsetlin subalgebra of
$U(\mathfrak{gl}_N),$ the non-commutative random walk matches a
(2+1)-dimensional random surface model introduced in [7]. As an application, it
is then proved that the moments converge to an explicit Gaussian field along
time-like paths. Combining with [7] which showed convergence to the Gaussian
free field along space-like paths, this computes the entire three-dimensional
Gaussian field. In particular, it matches a Gaussian field from eigenvalues of
random matrices [5].


title:
Q-dependence of the spin fluctuations in the intermediate valence
  compound CePd3

abstract:
  We report inelastic neutron scattering experiments on a single crystal of the
intermediate valence compound CePd3. At 300 K the magnetic scattering is
quasielastic, with halfwidth of 23 meV, and is independent of momentum transfer
Q. At low temperature, the Q-averaged magnetic spectrum is inelastic,
exhibiting a broad peak centered near Emax = 55 meV. These results, together
with the temperature dependence of the susceptibility, 4f occupation number,
and specific heat, can be fit by the Kondo/Anderson impurity model. The low
temperature scattering near Emax, however, shows significant variations with Q,
reflecting the coherence of the 4f lattice. The intensity is maximal at (1/2,
1/2,0), intermediate at (1/2,0,0) and (0,0,0), and weak at (1/2,1/2,1/2). We
discuss this Q-dependence in terms of current ideas about coherence in heavy
fermion systems.


title: The Strength of Friendship Ties in Proximity Sensor Data

abstract:
  Understanding how people interact and socialize is important in many contexts
from disease control to urban planning. Datasets that capture this specific
aspect of human life have increased in size and availability over the last few
years. We have yet to understand, however, to what extent such electronic
datasets may serve as a valid proxy for real life social interactions. For an
observational dataset, gathered using mobile phones, we analyze the problem of
identifying transient and non-important links, as well as how to highlight
important social interactions. Applying the Bluetooth signal strength parameter
to distinguish between observations, we demonstrate that weak links, compared
to strong links, have a lower probability of being observed at later times,
while such links--on average--also have lower link-weights and probability of
sharing an online friendship. Further, the role of link-strength is
investigated in relation to social network properties.


title: Population III Hypernovae

abstract:
  Population III supernovae have been of growing interest of late for their
potential to directly probe the properties of the first stars, particularly the
most energetic events that are visible near the edge of the observable
universe. But until now, hypernovae, the unusually energetic Type Ib/c
supernovae that are sometimes associated with gamma-ray bursts, have been
overlooked as cosmic beacons at the highest redshifts. In this, the latest of a
series of studies on Population III supernovae, we present numerical
simulations of 25 - 50 M$_{\odot}$ hypernovae and their light curves done with
the Los Alamos RAGE and SPECTRUM codes. We find that they will be visible at z
= 10 - 15 to the James Webb Space Telescope (JWST) and z = 4 - 5 to the
Wide-Field Infrared Survey Telescope (WFIRST), tracing star formation rates in
the first galaxies and at the end of cosmological reionization. If, however,
the hypernova crashes into a dense shell ejected by its progenitor, it is
expected that a superluminous event will occur that may be seen at z ~ 20, in
the first generation of stars.


title: Impact of LHC Run-1 on particle astrophysics

abstract:
  An overview of the impact of the first three years of LHC operation on two of
the most important open questions in astroparticle physics is presented.
Measurements in proton-proton collisions at the energy frontier that provide
valuable information on the identity of the highest-energy particles in the
cosmos as well as new constraints on the nature of dark matter, are summarized.


title:
A way forward in the study of the symmetry energy: experiment, theory,
  and observation

abstract:
  The symmetry energy describes how the energy of nuclear matter rises as one
goes away from equal numbers of neutrons and protons. This is very important to
describe neutron rich matter in astrophysics. This article reviews our
knowledge of the symmetry energy from theoretical calculations, nuclear
structure measurements, heavy ion collisions, and astronomical observations. We
then present a roadmap to make progress in areas of relevance to the symmetry
energy that promotes collaboration between the astrophysics and the nuclear
physics communities.


title: Microstructure and Conductance-Slope of InAs/GaSb Tunnel Diodes

abstract:
  InAs/GaSb and similar materials systems have generated great interest as a
heterojunction for tunnel field effect transistors (TFETs) due to favorable
band alignment. However, little is currently understood about how such TFETs
are affected by materials defects and nonidealities. We present measurements of
the conductance slope for various InAs/GaSb heterojunctions via two-terminal
electrical measurements, which removes three-terminal parasitics and enables
direct study on the effect of microstructure on tunnelling. Using this, we can
predict how subthreshold swings in TFETs can depend on microstructure. We also
demonstrate growth and electrical characterization for structures grown by
metalorganic chemical vapor deposition (MOCVD) - a generally more scalable
process compared to molecular beam epitaxy (MBE). We determine that misfit
dislocations and point defects near the interface can lead to energy states in
the band-gap and local band bending that result in trap-assisted leakage routes
and nonuniform band alignment across the junction area that lower the steepness
of the conductance slope. Despite the small lattice mismatch, misfit
dislocations still form in InAs on GaSb due to relaxation as a result of large
strain from intermixed compositions. This can be circumvented by growing GaSb
on InAs, straining the GaSb underlayer, or lowering the InAs growth temperature
in the region of the interface. The conductance slope can also be improved by
annealing the samples at higher temperatures, which we believe acts to
annihilate point defects and average out major fluctuations in band alignment
across the interface. Using a combination of these techniques, we can greatly
improve the steepness of the conductance slope which could result in steeper
subthreshold swings in TFETs in the future.