title:
Regularization parameter independent analysis in Nambu-Jona-Lasinio
  model

abstract:
  Nambu-Jona-Lasinio model used to investigate low energy phenomena is
nonrenormalizable, therefore the results depend on the regularization parameter
in general. A possibility of the finite in four-dimensional limit and even the
regularization parameter (this is dimension in the dimensional regularization
scheme) independent analysis is shown in the leading order of the 1/Nc
expansion.


title: Gauge invariance at work in FDR: H -> gamma gamma

abstract:
  We present the first complete calculation performed within the Four
Dimensional Regularization scheme (FDR), namely the loop-induced on-shell
amplitude for the Higgs boson decay into two photons in an arbitrary R_csi
gauge. FDR is a new technique -free of infinities- for addressing multi-loop
calculus, which automatically preserves gauge invariance, allowing for a
4-dimensional computation at the same time. We obtained the same result as that
assessed in dimensional regularization, thereby explicitly verifying, in a
realistic case, that FDR respects gauge invariance.


title: Asymmetric Quantum Codes: New Codes from Old

abstract:
  In this paper we extend to asymmetric quantum error-correcting codes (AQECC)
the construction methods, namely: puncturing, extending, expanding, direct sum
and the (u|u + v) construction. By applying these methods, several families of
asymmetric quantum codes can be constructed. Consequently, as an example of
application of quantum code expansion developed here, new families of
asymmetric quantum codes derived from generalized Reed-Muller (GRM) codes,
quadratic residue (QR), Bose-Chaudhuri-Hocquenghem (BCH), character codes and
affine-invariant codes are constructed.


title: The k-space Origins of Scattering in Bi2Sr2CaCu2O8+x

abstract:
  We demonstrate a general, computer automated procedure that inverts the
q-space scattering data measured by spectroscopic imaging scanning tunneling
microscopy (SI-STM) to determine the k-space scattering structure. This allows
a detailed examination of the k-space origins of the quasiparticle interference
(QPI) pattern in Bi2Sr2CaCu2O8+x. This new method allows the measurements of
the differences between the positive and negative energy dispersions, the gap
structure and it also measures energy dependent scattering length scale.
Furthermore, the transitions between the dispersive QPI, the checkerboard and
the pseudogap are mapped in detail allowing the exact nature of these
transitions to be determined for both positive and negative energies. We are
also able to measure the k-space scattering structure over a wide range of
doping (p ~ 0.22 to 0.08), including regions where the octet model is not
applicable. Our technique allows a complete picture of the k-space origins of
the spatial excitations in Bi2Sr2CaCu2O8+x to be mapped out, providing for
better comparisons between SI-STM and other experimental probes of the band
structure and validating our new general approach for determining the k-space
scattering origins from SI-STM data.


title: Knapsack Problems in Groups

abstract:
  We generalize the classical knapsack and subset sum problems to arbitrary
groups and study the computational complexity of these new problems. We show
that these problems, as well as the bounded submonoid membership problem, are
P-time decidable in hyperbolic groups and give various examples of finitely
presented groups where the subset sum problem is NP-complete.


title: Uniqueness of the contact structure approximating a foliation

abstract:
  According to a theorem of Eliashberg and Thurston a $C^2$-foliation on a
closed 3-manifold can be $C^0$-approximated by contact structures unless all
leaves of the foliation are spheres. Examples on the 3-torus show that every
neighbourhood of a foliation can contain non-diffeomorphic contact structures.
  In this paper we show uniqueness up to isotopy of the contact structure in a
small neighbourhood of the foliation when the foliation has no torus leaf and
is not a foliation without holonomy on parabolic torus bundles over the circle.
This allows us to associate invariants from contact topology to foliations. As
an application we show that the space of taut foliations in a given homotopy
class of plane fields is not connected in general.


title:
Nest graphs and minimal complete symmetry groups for magic Sudoku
  variants

abstract:
  A symmetry group for Sudoku is complete if its action partitions the set of
Sudoku boards into all possible orbits, and minimal if no group of smaller size
would do the same. Previously, for a 4 x 4 Sudoku variation known as Shidoku,
the authors used an analogous symmetry group to partition the set of Shidoku
boards into so-called "nests" and then use the interplay between the physical
and relabeling symmetries to find certain subgroups that were both complete and
minimal. In this paper these same techniques are applied to find a minimal
complete symmetry group for the modular magic Sudoku variation, as well as for
another Sudoku variation called semi-magic Sudoku. The paper concludes with a
simple computation which leads to the non-obvious fact that the full Sudoku
symmetry group is, in fact, already minimal and complete.


title: Factorization of Z-homogeneous polynomials in the First (q)-Weyl Algebra

abstract:
  We present algorithms to factorize weighted homogeneous elements in the first
polynomial Weyl algebra and $q$-Weyl algebra, which are both viewed as a
$\mathbb{Z}$-graded rings. We show, that factorization of homogeneous
polynomials can be almost completely reduced to commutative univariate
factorization over the same base field with some additional uncomplicated
combinatorial steps. This allows to deduce the complexity of our algorithms in
detail. Furthermore, we will show for homogeneous polynomials that
irreducibility in the polynomial first Weyl algebra also implies irreducibility
in the rational one, which is of interest for practical reasons. We report on
our implementation in the computer algebra system \textsc{Singular}. It
outperforms for homogeneous polynomials currently available implementations
dealing with factorization in the first Weyl algebra both in speed and elegancy
of the results.


title: Development of Yes/No Arabic Question Answering System

abstract:
  Developing Question Answering systems has been one of the important research
issues because it requires insights from a variety of
disciplines,including,Artificial Intelligence,Information Retrieval,
Information Extraction,Natural Language Processing, and Psychology.In this
paper we realize a formal model for a lightweight semantic based open domain
yes/no Arabic question answering system based on paragraph retrieval with
variable length. We propose a constrained semantic representation. Using an
explicit unification framework based on semantic similarities and query
expansion synonyms and antonyms.This frequently improves the precision of the
system. Employing the passage retrieval system achieves a better precision by
retrieving more paragraphs that contain relevant answers to the question; It
significantly reduces the amount of text to be processed by the system.


title: Every strongly summable ultrafilter on $\bigoplus\mathbb Z_2$ is sparse

abstract:
  We investigate the possibility of the existence of nonsparse strongly
summable ultrafilters on certain abelian groups. In particular, we show that
every strongly summable ultrafilter on the countably infinite Boolean group is
sparse. This answers a question of Hindman, Stepr\=ans and Strauss.


title:
The impact of teaching two courses (electronic curriculum design,
  multimedia) on the acquisition of electronic content design skills

abstract:
  The use of Multimedia applications in Learning provides useful concepts for
Instructional Content Design. This study aimed to investigate the effect of
design electronic curriculum and multimedia applications on acquiring e-content
design skills, and improving their attitudes towards e-learning. To achieve the
objective of the study, the researchers developed a test to measure the
efficiencies of designing electronic content and the measure of attitudes
towards e-learning, The results showed that study of both courses contributed
positively to the acquisition of design skills of e-content, The results
revealed that there are statistical significant differences between the scores
of the students in the two applications (pre and post) on the total score of
the attitude measure and three areas of it.


title:
Gyrations: The Missing Link Between Classical Mechanics with its
  Underlying Euclidean Geometry and Relativistic Mechanics with its Underlying
  Hyperbolic Geometry

abstract:
  Being neither commutative nor associative, Einstein velocity addition of
relativistically admissible velocities gives rise to gyrations. Gyrations, in
turn, measure the extent to which Einstein addition deviates from commutativity
and from associativity. Gyrations are geometric automorphisms abstracted from
the relativistic mechanical effect known as Thomas precession.


title:
Memory Aware Load Balance Strategy on a Parallel Branch-and-Bound
  Application

abstract:
  The latest trends in high-performance computing systems show an increasing
demand on the use of a large scale multicore systems in a efficient way, so
that high compute-intensive applications can be executed reasonably well.
However, the exploitation of the degree of parallelism available at each
multicore component can be limited by the poor utilization of the memory
hierarchy available. Actually, the multicore architecture introduces some
distinct features that are already observed in shared memory and distributed
environments. One example is that subsets of cores can share different subsets
of memory. In order to achieve high performance it is imperative that a careful
allocation scheme of an application is carried out on the available cores,
based on a scheduling model that considers the main performance bottlenecks, as
for example, memory contention. In this paper, the {\em Multicore Cluster
Model} (MCM) is proposed, which captures the most relevant performance
characteristics in multicores systems such as the influence of memory hierarchy
and contention. Better performance was achieved when a load balance strategy
for a Branch-and-Bound application applied to the Partitioning Sets Problem is
based on MCM, showing its efficiency and applicability to modern systems.


title: Machine learning for predictive condensed-phase simulation

abstract:
  We show how machine learning techniques based on Bayesian inference can be
used to reach new levels of realism in the computer simulation of molecular
materials, focusing here on water. We train our machine-learning algorithm
using accurate, correlated quantum chemistry, and predict energies and forces
in molecular aggregates ranging from clusters to solid and liquid phases. The
widely used electronic-structure methods based on density-functional theory
(DFT) give poor accuracy for molecular materials like water, and we show how
our techniques can be used to generate systematically improvable corrections to
DFT. The resulting corrected DFT scheme gives remarkably accurate predictions
for the relative energies of small water clusters and of different ice
structures, and greatly improves the description of the structure and dynamics
of liquid water.


title:
Weighted Sets of Probabilities and Minimax Weighted Expected Regret: New
  Approaches for Representing Uncertainty and Making Decisions

abstract:
  We consider a setting where an agent's uncertainty is represented by a set of
probability measures, rather than a single measure. Measure-by-measure updating
of such a set of measures upon acquiring new information is well-known to
suffer from problems; agents are not always able to learn appropriately. To
deal with these problems, we propose using weighted sets of probabilities: a
representation where each measure is associated with a weight, which denotes
its significance. We describe a natural approach to updating in such a
situation and a natural approach to determining the weights. We then show how
this representation can be used in decision-making, by modifying a standard
approach to decision making -- minimizing expected regret -- to obtain minimax
weighted expected regret (MWER). We provide an axiomatization that
characterizes preferences induced by MWER both in the static and dynamic case.


title:
Lasercooled radium monofluoride: A molecular all-in-one probe for new
  physics

abstract:
  The particular advantages of using the diatomic molecule radium monofluoride
(RaF) as a versatile molecular probe for physics beyond the Standard Model are
highlighted. i) RaF was previously suggested as being potentially amenable to
direct cooling with lasers. As shown in the present work, RaF's energetically
lowest electronically excited state is of ${}^{2}\Pi$ symmetry (in contrast to
BaF), such that no low-lying ${}^{2}\Delta$ state prevents efficient optical
cooling cycles. ii) The effective electric field acting on the unpaired
electron in the electronic ground state of RaF is estimated larger than in YbF,
from which the best restrictions on the electron electric dipole moment (eEDM)
were obtained experimentally. iii) Favourable crossings of spin-rotational
levels of opposite parity in external magnetic fields exist, which are
important for the measurement of the nuclear anapole moment of nuclei with a
valence neutron. Thus, RaF appears currently as one of the most attractive
candidates for investigation of parity-odd as well as simultaneously parity-
and time-reversal-odd interactions in the realms of molecular physics.


title: STEVE - Space-Time-Enclosing Volume Extraction

abstract:
  The novel STEVE (i.e., Space-Time-Enclosing Volume Extraction) algorithm is
described here for the very first time. It generates iso-valued hypersurfaces
that may be implicitly contained in four-dimensional (4D) data sets, such as
temporal sequences of three-dimensional images from time-varying computed
tomography. Any final hypersurface that will be generated by STEVE is
guaranteed to be free from accidental rifts, i.e., it always fully encloses a
region in the 4D space under consideration. Furthermore, the information of the
interior/exterior of the enclosed regions is propagated to each one of the
tetrahedrons, which are embedded into 4D and which in their union represent the
final, iso-valued hypersurface(s). STEVE is usually executed in a purely
data-driven mode, and it uses lesser computational resources than other
techniques that also generate simplex-based manifolds of codimension 1.


title:
Puzzles in Hadronic Physics and Novel Quantum Chromodynamics
  Phenomenology

abstract:
  We review some outstanding puzzles and experimental anomalies in hadron
physics that appear to challenge conventional wisdom and, in some cases, the
foundations of QCD. We also discuss possible solutions and propose new tests
and experiments that could illuminate the underlying physics and novel
phenomenological features of QCD. In some cases, new perspectives for QCD
physics have emerged.


title: Status of the Calan-Hertfordshire Extrasolar Planet Search

abstract:
  In these proceedings we give a status update of the Calan-Hertfordshire
Extrasolar Planet Search, an international collaboration led from Chile that
aims to discover more planets around super metal-rich and Sun-like stars, and
then follow these up with precision photometry to hunt for new bright transit
planets. We highlight some results from this program, including exoplanet and
brown dwarf discoveries, and a possible correlation between metallicity and
planetary minimum mass at the lowest planetary masses detectable. Finally we
discuss the short-term and long-term future pathways this program can take.


title: Ricci flows with bursts of unbounded curvature

abstract:
  Given a completely arbitrary surface, whether or not it has bounded
curvature, or even whether or not it is complete, there exists an
instantaneously complete Ricci flow evolution of that surface that exists for a
specific amount of time [GT11]. In the case that the underlying Riemann surface
supports a hyperbolic metric, this Ricci flow always exists for all time and
converges (after scaling by a factor $\frac1{2t}$) to this hyperbolic metric
[GT11], i.e. our Ricci flow geometrises the surface. In this paper we show that
there exist complete, bounded curvature initial metrics, including those
conformal to a hyperbolic metric, which have subsequent Ricci flows developing
unbounded curvature at certain intermediate times. In particular, when coupled
with the uniqueness from [Top13], we find that any complete Ricci flow starting
with such initial metrics must develop unbounded curvature over some
intermediate time interval, but that nevertheless, the curvature must later
become bounded and the flow must achieve geometrisation as $t\to\infty$, even
though there are other conformal deformations to hyperbolic metrics that do not
involve unbounded curvature.
  Another consequence of our constructions is that while our Ricci flow from
[GT11] must agree initially with the classical flow of Hamilton and Shi in the
special case that the initial surface is complete and of bounded curvature, by
uniqueness, it is now clear that our flow lasts for a longer time interval in
general, with Shi's flow stopping when the curvature blows up, but our flow
continuing strictly beyond in these situations.
  All our constructions of unbounded curvature developing and then disappearing
are in two dimensions. Generalisations to higher dimensions are then immediate.


title: A Geometric transition from hyperbolic to anti de Sitter geometry

abstract:
  We introduce a geometric transition between two homogeneous three-dimensional
geometries: hyperbolic geometry and anti de Sitter (AdS) geometry. Given a path
of three-dimensional hyperbolic structures that collapse down onto a hyperbolic
plane, we describe a method for constructing a natural continuation of this
path into AdS structures. In particular, when hyperbolic cone manifolds
collapse, the AdS manifolds generated on the "other side" of the transition
have tachyon singularities. The method involves the study of a new transitional
geometry called half-pipe geometry. We demonstrate these methods in the case
when the manifold is the unit tangent bundle of the (2,m,m) triangle orbifold
for m at least 5.


title: Asymptotically liberating sequences of random unitary matrices

abstract:
  A fundamental result of free probability theory due to Voiculescu and
subsequently refined by many authors states that conjugation by independent
Haar-distributed random unitary matrices delivers asymptotic freeness. In this
paper we exhibit many other systems of random unitary matrices that, when used
for conjugation, lead to freeness. We do so by first proving a general result
asserting "asymptotic liberation" under quite mild conditions, and then we
explain how to specialize these general results in a striking way by exploiting
Hadamard matrices. In particular, we recover and generalize results of the
second-named author and of Tulino-Caire-Shamai-Verd\'{u}.


title: Meta-Monoids, Meta-Bicrossed Products, and the Alexander Polynomial

abstract:
  We introduce a new invariant of tangles along with an algebraic framework in
which to understand it. We claim that the invariant contains the classical
Alexander polynomial of knots and its multivariable extension to links. We
argue that of the computationally efficient members of the family of Alexander
invariants, it is the most meaningful.
  These are lecture notes for talks given by the first author, written and
completed by the second. The talks, with handouts and videos, are available at
http://www.math.toronto.edu/drorbn/Talks/Regina-1206/. See also further
comments at http://www.math.toronto.edu/drorbn/Talks/Caen-1206/#June8.


title: Scalar-tensor theories and asymmetric resonant cavities

abstract:
  Recently published experimental results indicate the appeareance of unusual
forces on asymmetric, electromagnetic resonant cavities. It is argued here that
a particular class of scalar-tensor theories of gravity could account for this
effect.


title:
Nature of the anomalies in the supercooled liquid state of the mW model
  of water

abstract:
  The thermodynamic properties of the supercooled liquid state of the mW model
of water show anomalous behavior. Like in real water, the heat capacity and
compressibility sharply increase upon supercooling. One of the possible
explanations of these anomalies, the existence of a second (liquid-liquid)
critical point, is not supported by simulations for this model. In this work,
we reproduce the anomalies of the mW model with two thermodynamic scenarios:
one based on a non-ideal "mixture" with two different types of local order of
the water molecules, and one based on weak crystallization theory. We show that
both descriptions accurately reproduce the model's basic thermodynamic
properties. However, the coupling constant required for the power laws implied
by weak crystallization theory is too large relative to the regular
backgrounds, contradicting assumptions of weak crystallization theory.
Fluctuation corrections outside the scope of this work would be necessary to
fit the forms predicted by weak crystallization theory. For the two-state
approach, the direct computation of the low-density fraction of molecules in
the mW model is in agreement with the prediction of the phenomenological
equation of state. The non-ideality of the "mixture" of the two states never
becomes strong enough to cause liquid-liquid phase separation, also in
agreement with simulation results.


title:
Universal homomorphisms, universal structures, and the polymorphism
  clones of homogeneous structures

abstract:
  Using a categorial version of Fra\"iss\'e's theorem due to Droste and
G\"obel, we derive a criterion for a comma-category to have universal
homogeneous objects.
  As a first application we give new existence result for universal structures
and for \omega-categorical universal structures.
  As a second application we characterize the retracts of a large class of
homogeneous structures, extending previous results by Bonato, Deli\'c, Dolinka,
and Kubi\'s.
  As a third application we show for a large class of homogeneous structures
that their polymorphism clone is generated by polymorphisms of bounded arity,
generalizing a classical result by Sierpi\'nski that the clone of all functions
on a given set is generated by its binary part.
  Further we study the cofinality and the Bergman property for clones and we
give sufficient conditions on a homogeneous structure to have a polymorphism
clone that has uncountable cofinality and the Bergman property.


title: Correlations in lowest Landau level vortex states

abstract:
  We show how the configuration-space form of the Bogoliubov ground state wave
function of a bosonic condensate with a single vortex in a harmonic trap can be
described in terms of bosonic Jastrow correlations. We then generalize this
result to study the first effects of such correlations on a mean-field vortex
lattice state and show that the included correlations lower the energy below
that of the mean-field state. Although the reduction is relatively small, it is
a precursor of the more general expected effect of correlations in describing
the melting of the vortex lattice at large angular momentum per particle.


title: Status of invisible Higgs decays

abstract:
  We analyze the extent to which the LHC and Tevatron results as of the end of
2012 constrain invisible (or undetected) decays of the Higgs boson-like state
at ~ 125 GeV. To this end we perform global fits for several cases: 1) a Higgs
boson with Standard Model (SM) couplings but additional invisible decay modes;
2) SM couplings to fermions and vector bosons, but allowing for additional new
particles modifying the effective Higgs couplings to gluons and photons; 3) no
new particles in the loops but tree-level Higgs couplings to the up-quarks,
down-quarks and vector bosons, relative to the SM, treated as free parameters.
We find that in the three cases invisible decay rates of 23%, 61%, 88%,
respectively, are consistent with current data at 95% confidence level (CL).
Limiting the coupling to vector bosons, CV, to CV < 1 in case 3) reduces the
allowed invisible branching ratio to 56% at 95% CL. Requiring in addition that
the Higgs couplings to quarks have the same sign as in the SM, an invisible
rate of up to 36% is allowed at 95% CL. We also discuss direct probes of
invisible Higgs decays, as well as the interplay with dark matter searches.


title: Quantum matter in quantum space-time

abstract:
  Quantum matter in quantum space-time is discussed using general properties of
energy-conservation laws. As a rather radical conclusion, it is found that
standard methods of differential geometry and quantum field theory on curved
space-time are inapplicable in canonical quantum gravity, even at the level of
effective equations.


title:
Capacity Bounds for Wireless Ergodic Fading Broadcast Channels with
  Partial CSIT

abstract:
  The two-user wireless ergodic fading Broadcast Channel (BC) with partial
Channel State Information at the Transmitter (CSIT) is considered. The CSIT is
given by an arbitrary deterministic function of the channel state. This
characteristic yields a full control over how much state information is
available, from perfect to no information. In literature, capacity derivations
for wireless ergodic fading channels, specifically for fading BCs, mostly rely
on the analysis of channels comprising of parallel sub-channels. This technique
is usually suitable for the cases where perfect state information is available
at the transmitters. In this paper, new arguments are proposed to directly
derive (without resorting to the analysis of parallel channels) capacity bounds
for the two-user fading BC with both common and private messages based on the
existing bounds for the discrete channel. Specifically, a novel approach is
developed to adapt and evaluate the well-known UV-outer bound for the Gaussian
fading channel using the entropy power inequality. Our approach indeed sheds
light on the role of broadcast auxiliaries in the fading channel. It is shown
that the derived outer bound is optimal for the channel with perfect CSIT as
well as for some special cases with partial CSIT. Our outer bound is also
directly applicable to the case without CSIT which has been recently considered
in several papers. Next, the approach is developed to analyze for the fading BC
with secrecy. In the case of perfect CSIT, a full characterization of the
secrecy capacity region is derived for the channel with common and confidential
messages. This result completes a gap in a previous work by Ekrem and Ulukus.
For the channel without common message, the secrecy capacity region is also
derived when the transmitter has access only to the degradedness ordering of
the channel.


title: Criteria for solvable radical membership via p-elements

abstract:
  Guralnick, Kunyavskii, Plotkin and Shalev have shown that the solvable
radical of a finite group $G$ can be characterized as the set of all $x\in G$
such that $<x,y>$ is solvable for all $y\in G$. We prove two generalizations of
this result. Firstly, it is enough to check the solvability of $<x,y>$ for
every $p$-element $y\in G$ for every odd prime $p$. Secondly, if $x$ has odd
order, then it is enough to check the solvability of $<x,y>$ for every
2-element $y\in G$.


title: s-f(d) exchange mechanism of magnon generation by slow spinpolarons

abstract:
  It is shown that in a single-axis antiferromagnetic semiconductor placed in a
strong magnetic field, dispersionless magnons start emitting at any arbitrarily
small velocity of an electron occurring in a spinpolaron state. If magnons are
dispersed they are generated when the spinpolaron velocity exceeds the minimum
phase velocity of magnons. The maximum power of magnon generation caused by the
drift of spinpolarons is estimated.


title:
Vindicating single-T modified blackbody fits to Herschel SEDs (Research
  Note)

abstract:
  I show here that the bulk of the dust mass in a galaxy can be equivalently
estimated from: i) the full spectral energy distribution of dust emission,
using the approach of Draine & Lee (2007) that includes a distribution of dust
grains and a range of interstellar radiation field intensities; ii) the
emission in the wavelength range 100um <= lambda <= 500um (covered by the
Herschel Space Observatory), by fitting to the data a simpler single
temperature modified blackbody. Recent claims on the contrary (Dale et al.
2012) should be interpreted as a caveat to use in the simpler fits an
absorption cross section which is consistent both in the normalization and in
the spectral index beta with that of the full dust model. I also show that the
dust mass does not depend significantly on the choice of beta, if both the dust
mass and the absorption cross section are derived with the same assumption on
beta.


title:
The Post-Merger Magnetized Evolution of White Dwarf Binaries: The
  Double-Degenerate Channel of Sub-Chandrasekhar Type Ia Supernovae and the
  Formation of Magnetized White Dwarfs

abstract:
  Type Ia supernovae (SNe Ia) play a crucial role as standardizable
cosmological candles, though the nature of their progenitors is a subject of
active investigation. Recent observational and theoretical work has pointed to
merging white dwarf binaries, referred to as the double-degenerate channel, as
the possible progenitor systems for some SNe Ia. Additionally, recent
theoretical work suggests that mergers which fail to detonate may produce
magnetized, rapidly-rotating white dwarfs. In this paper, we present the first
multidimensional simulations of the post-merger evolution of white dwarf
binaries to include the effect of the magnetic field. In these systems, the two
white dwarfs complete a final merger on a dynamical timescale, and are tidally
disrupted, producing a rapidly-rotating white dwarf merger surrounded by a hot
corona and a thick, differentially-rotating disk. The disk is strongly
susceptible to the magnetorotational instability (MRI), and we demonstrate that
this leads to the rapid growth of an initially dynamically weak magnetic field
in the disk, the spin-down of the white dwarf merger, and to the subsequent
central ignition of the white dwarf merger. Additionally, these magnetized
models exhibit new features not present in prior hydrodynamic studies of white
dwarf mergers, including the development of MRI turbulence in the hot disk,
magnetized outflows carrying a significant fraction of the disk mass, and the
magnetization of the white dwarf merger to field strengths $\sim 2 \times 10^8$
G. We discuss the impact of our findings on the origins, circumstellar media,
and observed properties of SNe Ia and magnetized white dwarfs.


title: Distinct stellar populations in the inner bars of double-barred galaxies

abstract:
  Numerical simulations of double-barred galaxies predict the build-up of
different structural components (e.g., bulges, inner discs) in the central
regions of disc galaxies. In those simulations, inner bars have a prominent
role in the internal secular evolution of their host galaxies. The development
of bulges and inner discs is, however, poorly understood observationally due to
the small number of studies focusing on the stellar populations of these
systems. In order to provide constraints on the relevant processes inducing the
creation of these components in the presence of inner bars, we have carried out
a detailed kinematical and stellar population analysis in a sample of four
double-barred galaxies, ranging from SB0 to SBb, observed with integral-field
spectroscopy. We find that the inner bars present distinct stellar population
properties, being younger and more metal-rich than the surrounding bulges and
outer bars. While we detect signatures of gas inflow through the inner bars, we
find no evidence of associated star-forming regions or newly-formed structures
around them. This result suggests that, regardless of their formation scenario,
at present these inner bars are playing a moderate or even a minor role in the
morphological evolution of this sample of double-barred galaxies.


title:
Astrophysical black holes as natural laboratories for fundamental
  physics and strong-field gravity

abstract:
  Astrophysical tests of general relativity belong to two categories: 1)
"internal", i.e. consistency tests within the theory (for example, tests that
astrophysical black holes are indeed described by the Kerr solution and its
perturbations), or 2) "external", i.e. tests of the many proposed extensions of
the theory. I review some ways in which astrophysical black holes can be used
as natural laboratories for both "internal" and "external" tests of general
relativity. The examples provided here (ringdown tests of the black hole
"no-hair" theorem, bosonic superradiant instabilities in rotating black holes
and gravitational-wave tests of massive scalar-tensor theories) are shamelessly
biased towards recent research by myself and my collaborators. Hopefully this
colloquial introduction aimed mainly at astrophysicists will convince skeptics
(if there are any) that space-based detectors will be crucial to study
fundamental physics through gravitational-wave observations.


title: Holographic Local Quenches and Entanglement Density

abstract:
  We propose a free falling particle in an AdS space as a holographic model of
local quench. Local quenches are triggered by local excitations in a given
quantum system. We calculate the time-evolution of holographic entanglement
entropy. We confirm a logarithmic time-evolution, which is known to be typical
in two dimensional local quenches. To study the structure of quantum
entanglement in general quantum systems, we introduce a new quantity which we
call entanglement density and apply this analysis to quantum quenches. We show
that this quantity is directly related to the energy density in a small size
limit. Moreover, we find a simple relationship between the amount of quantum
information possessed by a massive object and its total energy based on the
AdS/CFT.


title:
Radio and Mid-Infrared Properties of Compact Starbursts: Distancing
  Themselves from the Main Sequence

abstract:
  We investigate the relationship between 8.44\,GHz brightness temperatures and
1.4 to 8.44\,GHz radio spectral indices with 6.2\,$\mu$m polycyclic aromatic
hydrocarbon (PAH) emission and 9.7\,$\mu$m silicate absorption features for a
sample of 36 local luminous and ultra-luminous infrared galaxies. We find that
galaxies having small 6.2\,$\mu$m PAH equivalent widths (EQWs), which signal
the presence of weak PAH emission and/or an excess of very hot dust, also have
flat spectral indices. The three active galactic nuclei (AGN) identified
through their excessively large 8.44\,GHz brightness temperatures are also
identified as AGN via their small 6.2\,$\mu$m PAH EQWs. We also find that the
flattening of the radio spectrum increases with increasing silicate optical
depth, 8.44\,GHz brightness temperature, and decreasing size of the radio
source even after removing potential AGN, supporting the idea that compact
starbursts show spectral flattening as the result of increased free-free
absorption. These correlations additionally suggest that the dust obscuration
in these galaxies must largely be coming from the vicinity of the compact
starburst itself, and is not distributed throughout the (foreground) disk of
the galaxy. Finally, we investigate the location of these infrared-bright
systems relative to the main sequence (star formation rate vs. stellar mass) of
star-forming galaxies in the local universe. We find that the radio spectral
indices of galaxies flattens with increasing distance above the main sequence,
or in other words, with increasing specific star formation rate. This indicates
that galaxies located above the main sequence, having high specific star
formation rates, are typically compact starbursts hosting deeply embedded star
formation that becomes more optically thick in the radio and infrared with
increased distance above the main sequence.


title:
Mapping H-band Scattered Light Emission in the Mysterious SR21
  Transitional Disk

abstract:
  We present the first near infrared (NIR) spatially resolved images of the
circumstellar transitional disk around SR21. These images were obtained with
the Subaru HiCIAO camera, adaptive optics and the polarized differential
imaging (PDI) technique. We resolve the disk in scattered light at H-band for
stellocentric 0.1"<r<0.6" (12<r<75AU). We compare our results with previously
published spatially-resolved 880 micron continuum Submillimeter Array (SMA)
images that show an inner r<36AU cavity in SR21. Radiative transfer models
reveal that the large disk depletion factor invoked to explain SR21's sub-mm
cavity cannot be "universal" for all grain sizes. Even significantly more
moderate depletions (delta=0.1, 0.01 relative to an undepleted disk) than those
that reproduce the sub-mm cavity (delta~10^-6) are inconsistent with our H-band
images when they are assumed to carry over to small grains, suggesting that
surface grains scattering in the NIR either survive or are generated by
whatever mechanism is clearing the disk midplane. In fact, the radial polarized
intensity profile of our H-band observations is smooth and steeply
inwardly-increasing (r^-3), with no evidence of a break at the 36AU sub-mm
cavity wall. We hypothesize that this profile is dominated by an optically thin
disk envelope or atmosphere component. We also discuss the compatibility of our
data with the previously postulated existence of a sub-stellar companion to
SR21 at r~10-20AU, and find that we can neither exclude nor verify this
scenario. This study demonstrates the power of multiwavelength imaging of
transitional disks to inform modeling efforts, including the debate over
precisely what physical mechanism is responsible for clearing these disks of
their large midplane grains.


title:
A new substantive proton to electron mass ratio constraint on rolling
  scalar field cosmologies

abstract:
  New PKS1830-211 radio frequency observations of methanol at a redshift of
0.88582 have established the most stringent limits on changes in the proton to
electron mass ratio mu to date. The observations place the limit of (delta
mu)/mu </= (0.0 +/- 1.0) x 10^{-7} which is approximately a factor of four
lower than the previous lowest limit at a redshift of 0.6742. This stringent
limit at a look back time of roughly half the age of the universe has profound
implications for rolling scalar field cosmologies and the new physics that they
require. Many of these cosmologies invoke a scalar field phi that is also
coupled to the electromagnetic field causing the values of the fundamental
constants, mu and the fine structure constant alpha to roll with time. If the
lowest expected value of the coupling to mu, zeta_{mu}$ is invoked the new
limit requires a limit on the dark energy equation of state parameter w such
that w+1 </= 0.001 at a redshift of 0.88582. This eliminates almost all of the
expected parameter space for such cosmologies and new physics that have a
coupling to the electromagnetic field. In these cases the limit requires that w
must be extremely close to -1 for the last half of the age of the universe or
that the coupling of the rolling scalar field to mu and the electromagnetic
field be significantly below or at the limit of its expected range. The new
observations solidify the role of fundamental constants in providing probes of
the possible cosmologies and new physics to explain the acceleration of the
expansion of the universe.


title: Variation of Stellar Envelope Convection and Overshoot with Metallicity

abstract:
  We examine how metallicity affects convection and overshoot in the
superadiabatic layer of main sequence stars. We present results from a grid of
3D radiation hydrodynamic simulations with four metallicities ($Z=0.040$,
0.020, 0.010, 0.001), and spanning a range in effective temperature ($4950 <
\rm T_{\rm eff} < 6230$). We show that changing the metallicity alters
properties of the convective gas dynamics, and the structure of the
superadiabatic layer and atmosphere. Our grid of simulations show that the
amount of superadiabaticity, which tracks the transition from efficient to
inefficient convection, \rev{is sensitive to changes in metallicity. We find
that increasing the metallicity forces the location of the transition region to
lower densities and pressures, and results in larger mean and turbulent
velocities throughout the superadiabatic region.} We also quantify the degree
of convective overshoot in the atmosphere, and show that it increases with
metallicity as well.


title:
An Unexpected Congruence Modulo 5 for 4--Colored Generalized Frobenius
  Partitions

abstract:
  In his 1984 AMS Memoir, George Andrews defined the family of $k$--colored
generalized Frobenius partition functions. These are denoted by $c\phi_k(n)$
where $k\geq 1$ is the number of colors in question. In that Memoir, Andrews
proved (among many other things) that, for all $n\geq 0,$ $c\phi_2(5n+3) \equiv
0\pmod{5}.$ Soon after, many authors proved congruence properties for various
$k$--colored generalized Frobenius partition functions, typically with a small
number of colors.
  In 2011, Baruah and Sarmah proved a number of congruence properties for
$c\phi_4$, all with moduli which are powers of 4. In this brief note, we add to
the collection of congruences for $c\phi_4$ by proving this function satisfies
an unexpected result modulo 5. The proof is elementary, relying on Baruah and
Sarmah's results as well as work of Srinivasa Ramanujan.


title:
Surface Atom Motion to Move Iron Nanocrystals through Constrictions in
  Carbon Nanotubes under the Action of an Electric Current

abstract:
  Under the application of electrical currents, metal nanocrystals inside
carbon nanotubes can be bodily transported. We examine experimentally and
theoretically how an iron nanocrystal can pass through a constriction in the
carbon nanotube with a smaller cross-sectional area than the nanocrystal
itself. Remarkably, through in situ transmission electron imaging and
diffraction, we find that, while passing through a constriction, the
nanocrystal remains largely solid and crystalline and the carbon nanotube is
unaffected. We account for this behavior by a pattern of iron atom motion and
rearrangement on the surface of the nanocrystal. The nanocrystal motion can be
described with a model whose parameters are nearly independent of the
nanocrystal length, area, temperature, and electromigration force magnitude. We
predict that metal nanocrystals can move through complex geometries and
constrictions, with implications for both nanomechanics and tunable synthesis
of metal nanoparticles.


title:
Non-Equilibirum ionisation and cooling of metal-enriched gas in the
  presence of a photo-ionisation background

abstract:
  Simulations of the formation of galaxies, as well as ionisation models used
to interpret observations of quasar absorption lines, generally either assume
ionisation equilibrium or ignore the presence of the extra-galactic background
(EGB) radiation. We introduce a method to compute the non-equilibrium
ionisation and cooling of diffuse gas exposed to the EGB. Our method iterates
the ionisation states of the 11 elements that dominate the cooling and uses
tabulated ion-by-ion cooling and photo-heating efficiencies to update the
temperature of the gas. Our reaction network includes radiative and di-electric
recombination, collisional ionisation, photo-ionisation, Auger ionisation, and
charge transfer. We verify that our method reproduces published results for
collisional equilibrium, collisional non-equilibrium, and photo-ionised
equilibrium. Non-equilibrium effects can become very important in cooling gas,
particularly below 10^6 K. Photo-ionisation and non-equilibrium effects both
tend to boost the degree of ionisation and to reduce cooling efficiencies. The
effect of the EGB is larger for lower densities. Hence, photo-ionisation
affects cooling more under isochoric than under isobaric conditions.
Non-equilibrium effects are smaller in the presence of the EGB and are thus
overestimated when using collisional-only processes. The inclusion of the EGB
alters the observational diagnostics of diffuse, metal-enriched gas (e.g. metal
absorption lines) even more significantly than the cooling efficiencies. We
argue that the cooling efficiency should be considered if ionisation models are
used to infer physical conditions from observed line ratios, as the a priori
probability of observing gas is lower if its cooling time is shorter. We
provide on-line tables of ionisation fractions and cooling efficiencies for
equilibrium and non-equilibrium scenarios. (abridged)


title: On a game on graphs

abstract:
  We start with the well-known game below: Two players hold a sheet of paper to
their forehead on which a positive integer is written. The numbers are
consecutive and each player can only see the number of the other one. In each
time step, they either say nothing or tell what number they have. Both of them
will eventually figure out their number after a certain amount of time. The
game is rather cooperative than competitive, and employs the notions of common
knowledge and mutual knowledge. We generalize this game to arbitrary (directed
and non-directed) simple graphs and try to establish for which graphs one or
both of them will figure out the solution, and how long they do need to find
it. We give a complete answer for the case of two players, even if they are
both allowed to discuss before the start of the game.


title:
Probing the inner boundaries of Saturn's A ring with the Iapetus -1:0
  nodal bending wave

abstract:
  The Iapetus -1:0 nodal bending wave, the first spiral wave ever described in
Saturn's rings, has been seen again for the first time in 29 years. We
demonstrate that it is in fact the nodal bending wave, not the 1:0 apsidal
density wave as previously reported. We use wavelet analysis to determine the
wavelength profile, thus deriving the surface density at every point in the
region covered by the bending wave. This profile is consistent with surface
densities measured from more localized spiral density waves in the outer
Cassini Division and the inner and mid-A Ring, varying smoothly from the low
values of the former to the higher values of the latter.
  Most remarkably, our analysis indicates that there is no significant change
in surface density across the boundary between the outer Cassini Division and
the inner-A ring, despite the very abrupt increase in optical depth and
reflected brightness at this location. We consider anew the nature of the
classically identified "inner edge of the A ring," given that it does not
appear to be correlated with any abrupt increase in surface density. There is
an abrupt increase in surface density at the Pandora 5:4 density wave, ~300 km
outward of the A ring's inner edge. Further study is needed to robustly
interpret our findings in terms of particle properties and abundances, much
less to explain the origins of the implied structure.


title: Gravitational Wave Memory from Gamma Ray Bursts' Jets

abstract:
  While the possible roles of GRBs' progenitors as Gravitational Waves (GW)
sources have been extensively studied, little attention has been given to the
jet itself as a GW source. We expect the jet's acceleration to produce a GW
Memory signal. While all relativistic jet models display anti-beaming of GW
radiation away from the jet axis, thus radiating away from directions of GRBs'
gamma radiation, this effect is not overwhelming. The decrease of the signal
amplitude towards the cone of gamma-ray detectability is weak, and for some
models and parameters the GW signal reaches a significant amplitude for much of
the gamma-ray cone. Thus both signals may be jointly detected. We find
different waveforms and fourier signatures for uniform jets and structured jet
models - thus offering a method of using GW signatures to probe the internal
structure and acceleration of GRB jets. The GW signal peaks just outside the
jet (core) of a uniform (structuted) jet. Within the jet (core) the GW signal
displays wiggles, due to a polarization effect; thus for a uniform jet, the
peak amplitude accompanies a smoother signal than the peak of a structured jet.
For the most probable detection angle and for typical GRB parameters, we expect
frequencies < ~600Hz and amplitudes h~10^-25. Our estimates of the expected
signals suggest that the signals are not strong enough for a single cluster of
DECIGO nor for aLIGO's sensitivities. However, sensitivies of ~10^-25/sqrt(Hz)
in the DECIGO band should suffice to detect typical long GRBs at 2Gpc and short
GRBs at 200Mpc, implying a monthly event of a long GRB and a detection of a
short GRB every decade. In addition, we expect much more frequent detection of
GW from GRBs directed away from us, including orphan afterglows. The ultimate
DECIGO sensitivy should increase the range and enable detecting these signals
in all models even to high cosmological z.


title:
Bayes linear variance structure learning for inspection of large scale
  physical systems

abstract:
  Modelling of inspection data for large scale physical systems is critical to
assessment of their integrity. We present a general method for inference about
system state and associated model variance structure from spatially distributed
time series which are typically short, irregular, incomplete and not directly
observable. Bayes linear analysis simplifies parameter estimation and avoids
often-unrealistic distributional assumptions. Second-order exchangeability
judgements facilitate variance learning for sparse inspection time-series. The
model is applied to inspection data for minimum wall thickness from corroding
pipe-work networks on a full-scale offshore platform, and shown to give
materially different forecasts of remnant life compared to an equivalent model
neglecting variance learning.


title: Magnetic Reconnection Instabilities in Soft-Gamma Repeaters

abstract:
  We examine an external trigger mechanism that gives rise to the intense soft
gamma-ray repeater (SGR) giant flares. Out of the three giant flares, two
showcased the existence of a precursor, which we show to have had initiated the
main flare. We develop a reconnection model based on the hypothesis that
shearing motion of the footpoints causes the materialization of a Sweet-Parker
current layer in the magnetosphere. The thinning of this macroscopic layer due
to the development of an embedded super-hot turbulent current layer switches on
the impulsive Hall reconnection, which powers the giant flare. We show that the
thinning time is on the order of the pre-flare quiescent time.


title: Design principles for HgTe based topological insulator devices

abstract:
  The topological insulator properties of CdTe/HgTe/CdTe quantum wells are
theoretically studied. The CdTe/HgTe/CdTe quantum well behaves as a topological
insulator beyond a critical well width dimension. It is shown that if the
barrier(CdTe) and well-region(HgTe) are altered by replacing them with the
alloy Cd$_{x}% $Hg$_{1-x}$Te of various stoichiometries, the critical width can
be changed.The critical quantum well width is shown to depend on temperature,
applied stress, growth directions and external electric fields. Based on these
results, a novel device concept is proposed that allows to switch between a
normal semiconducting and topological insulator state through application of
moderate external electric fields.


title: Diffractive Microlensing: A New Probe of the Local Universe

abstract:
  Diffraction is important when nearby substellar objects gravitationally lens
distant stars. If the wavelength of the observation is comparable to the
Schwarzschild radius of lensing object, diffraction leaves an observable
imprint on the lensing signature. The SKA may have sufficient sensitivity to
detect the typical sources, giant stars in the bulge. The diffractive
signatures in a lensing event break the degeneracies between the mass of the
lens, its distance and proper motion.


title: Microscopic Description of Induced Fission

abstract:
  Selected aspects of the description of neutron-induced fission in 240Pu in
the framework of the nuclear energy density functional theory at finite
temperature are presented. In particular, we discuss aspects pertaining to the
choice of thermodynamic state variables, the evolution of fission barriers as
function of the incident neutron energy, and the temperatures of the fission
fragments.


title:
Stability of the reverse Blaschke-Santalo inequality for unconditional
  convex bodies

abstract:
  Mahler's conjecture asks whether the cube is a minimizer for the volume
product of a body and its polar in the class of symmetric convex bodies in R^n.
The corresponding inequality to the conjecture is sometimes called the the
reverse Blaschke-Santalo inequality. The conjecture is known in dimension two
and in several special cases. In the class of unconditional convex bodies,
Saint Raymond confirmed the conjecture, and Meyer and Reisner, independently,
characterized the equality case. In this paper we present a stability version
of these results and also show that any symmetric convex body, which is
sufficiently close to an unconditional body, satisfies the the reverse
Blaschke-Santalo inequality.


title: DECal: A Spectrophotometric Calibration System For DECam

abstract:
  DECal is a new calibration system for the CTIO 4 m Blanco telescope. It is
currently being installed as part of the Dark Energy Survey and will provide
both broadband flat fields and narrowband (about 1 nm bandwidth)
spectrophotometric calibration for the new Dark Energy Camera (DECam). Both of
these systems share a new Lambertian flat field screen. The broadband flat
field system uses LEDs to illuminate each photometric filter. The
spectrophotometric calibration system consists of a monochromator-based tunable
light source that is projected onto the flat field screen using a custom
line-to-spot fiber bundle and an engineered diffuser. Several calibrated
photodiodes positioned along the beam monitor the telescope throughput as a
function of wavelength. This system will measure the wavelength-dependent
instrumental response function of the total telescope+instrument system in the
range 300 < lambda < 1100nm. The spectrophotometric calibration will be
performed regularly (roughly once per month) to determine the spectral response
of the DECam system and to monitor changes in instrumental throughput during
the five year Dark Energy Survey project.


title:
Analyzing complex functional brain networks: fusing statistics and
  network science to understand the brain

abstract:
  Complex functional brain network analyses have exploded over the last eight
years, gaining traction due to their profound clinical implications. The
application of network science (an interdisciplinary offshoot of graph theory)
has facilitated these analyses and enabled examining the brain as an integrated
system that produces complex behaviors. While the field of statistics has been
integral in advancing activation analyses and some connectivity analyses in
functional neuroimaging research, it has yet to play a commensurate role in
complex network analyses. Fusing novel statistical methods with network-based
functional neuroimage analysis will engender powerful analytical tools that
will aid in our understanding of normal brain function as well as alterations
due to various brain disorders. Here we survey widely used statistical and
network science tools for analyzing fMRI network data and discuss the
challenges faced in filling some of the remaining methodological gaps. When
applied and interpreted correctly, the fusion of network scientific and
statistical methods has a chance to revolutionize the understanding of brain
function.


title:
Peaks and dips in Gaussian random fields: a new algorithm for the shear
  eigenvalues, and the excursion set theory

abstract:
  We present a new algorithm to sample the constrained eigenvalues of the
initial shear field associated with Gaussian statistics, called the `peak/dip
excursion-set-based' algorithm, at positions which correspond to peaks or dips
of the correlated density field. The computational procedure is based on a new
formula which extends Doroshkevich's unconditional distribution for the
eigenvalues of the linear tidal field, to account for the fact that halos and
voids may correspond to maxima or minima of the density field. The ability to
differentiate between random positions and special points in space around which
halos or voids may form (peaks/dips), encoded in the new formula and reflected
in the algorithm, naturally leads to a straightforward implementation of an
excursion set model for peaks and dips in Gaussian random fields - one of the
key advantages of this sampling procedure. In addition, it offers novel
insights into the statistical description of the cosmic web. As a first
physical application, we show how the standard distributions of shear
ellipticity and prolateness in triaxial models of structure formation are
modified by the constraint. In particular, we provide a new expression for the
conditional distribution of shape parameters given the density peak constraint,
which generalizes some previous literature work. The formula has important
implications for the modeling of non-spherical dark matter halo shapes, in
relation to their initial shape distribution. We also test and confirm our
theoretical predictions for the individual distributions of eigenvalues
subjected to the extremum constraint, along with other directly related
conditional probabilities. Finally, we indicate how the proposed sampling
procedure naturally integrates into the standard excursion set model,
potentially solving some of its well-known problems, and into the ellipsoidal
collapse framework. (abridged)


title:
Search for Higgs boson production in trilepton and like-charge
  electron-muon final states with the D0 detector

abstract:
  We present a search for Higgs bosons in multilepton final states in pp-bar
collisions at sqrt(s)=1.96 TeV recorded with the D0 detector at the Fermilab
Tevatron Collider, using the full Run II data set with integrated luminosities
of up to 9.7 fb-1. The multilepton states considered are two electron plus
muon, electron with two muons, muon with two hadronic tau leptons, and
like-charge electron-muon pairs. These channels directly probe the HVV (V=W,Z)
coupling of the Higgs boson in production and decay. The muon with two hadronic
tau lepton channel is also sensitive to H to tau lepton pair decays. Upper
limits at the 95% C.L on the rate of standard model Higgs boson production are
derived in the mass range 100 <= M_H <= 200 GeV. The expected and observed
limits are a factor of 6.3 and 8.4 above the predicted standard model cross
section at M_H=125 GeV. We also interpret the data in a fermiophobic Higgs
boson model.


title: Budget Feasible Mechanisms for Experimental Design

abstract:
  In the classical experimental design setting, an experimenter E has access to
a population of $n$ potential experiment subjects $i\in \{1,...,n\}$, each
associated with a vector of features $x_i\in R^d$. Conducting an experiment
with subject $i$ reveals an unknown value $y_i\in R$ to E. E typically assumes
some hypothetical relationship between $x_i$'s and $y_i$'s, e.g., $y_i \approx
\beta x_i$, and estimates $\beta$ from experiments, e.g., through linear
regression. As a proxy for various practical constraints, E may select only a
subset of subjects on which to conduct the experiment.
  We initiate the study of budgeted mechanisms for experimental design. In this
setting, E has a budget $B$. Each subject $i$ declares an associated cost $c_i
>0$ to be part of the experiment, and must be paid at least her cost. In
particular, the Experimental Design Problem (EDP) is to find a set $S$ of
subjects for the experiment that maximizes $V(S) = \log\det(I_d+\sum_{i\in
S}x_i\T{x_i})$ under the constraint $\sum_{i\in S}c_i\leq B$; our objective
function corresponds to the information gain in parameter $\beta$ that is
learned through linear regression methods, and is related to the so-called
$D$-optimality criterion. Further, the subjects are strategic and may lie about
their costs.
  We present a deterministic, polynomial time, budget feasible mechanism
scheme, that is approximately truthful and yields a constant factor
approximation to EDP. In particular, for any small $\delta > 0$ and $\epsilon >
0$, we can construct a (12.98, $\epsilon$)-approximate mechanism that is
$\delta$-truthful and runs in polynomial time in both $n$ and
$\log\log\frac{B}{\epsilon\delta}$. We also establish that no truthful,
budget-feasible algorithms is possible within a factor 2 approximation, and
show how to generalize our approach to a wide class of learning problems,
beyond linear regression.


title: Meter-baseline tests of sterile neutrinos at Daya Bay

abstract:
  We explore the sensitivity of an experiment at the Daya Bay site, with a
point radioactive source and a few meter baseline, to neutrino oscillations
involving one or more eV mass sterile neutrinos. We find that within a year,
the entire 3+2 and 1+3+1 parameter space preferred by global fits can be
excluded at the 3\sigma level, and if an oscillation signal is found, the 3+1
and 3+2 scenarios can be distinguished from each other at more than the 3\sigma
level provided one of the sterile neutrinos is lighter than 0.5 eV.


title: Landau-Zener dynamics of a nanoresonator containing a tunneling spin

abstract:
  We study the Landau-Zener dynamics of a tunneling spin coupled to a torsional
resonator. For strong spin-phonon coupling, when the oscillator frequency is
large compared to the tunnel splitting, the system exhibits multiple
Landau-Zener transitions. Entanglement of spin and mechanical angular momentum
results in abrupt changes of oscillator dynamics which coincide in time with
spin transitions. We show that a large number of spins on a single oscillator
coupled only through the in-phase phonon field behaves as a single large spin,
greatly enhancing the spin-phonon coupling. We compare purely quantum and
semiclassical dynamics of the system and discuss their experimental
realizations. An experiment is proposed in which the field sweep is used to
read out the exact quantum state of the mechanical resonator.


title: A solution to Sheil-Small's harmonic mapping problem for Jordan polygons

abstract:
  The problem of mapping the interior of a Jordan polygon univalently by the
Poisson integral of a step function was posed by T. Sheil-Small (1989). We
describe a simple solution using "ear clipping" from computational geometry.


title: Dirichlet series associated to quartic fields with given resolvent

abstract:
  Let $k$ be a cubic field. We give an explicit formula for the Dirichlet
series $\sum_K|\Disc(K)|^{-s}$, where the sum is over isomorphism classes of
all quartic fields whose cubic resolvent field is isomorphic to $k$. Our work
is a sequel to an unpublished preprint of Cohen, Diaz y Diaz, and Olivier, and
we include complete proofs of their results so as not to rely on unpublished
work.
  This is a companion to a previous paper where we compute the Dirichlet series
associated to cubic fields having a given quadratic resolvent.


title: Sparse Signal Estimation by Maximally Sparse Convex Optimization

abstract:
  This paper addresses the problem of sparsity penalized least squares for
applications in sparse signal processing, e.g. sparse deconvolution. This paper
aims to induce sparsity more strongly than L1 norm regularization, while
avoiding non-convex optimization. For this purpose, this paper describes the
design and use of non-convex penalty functions (regularizers) constrained so as
to ensure the convexity of the total cost function, F, to be minimized. The
method is based on parametric penalty functions, the parameters of which are
constrained to ensure convexity of F. It is shown that optimal parameters can
be obtained by semidefinite programming (SDP). This maximally sparse convex
(MSC) approach yields maximally non-convex sparsity-inducing penalty functions
constrained such that the total cost function, F, is convex. It is demonstrated
that iterative MSC (IMSC) can yield solutions substantially more sparse than
the standard convex sparsity-inducing approach, i.e., L1 norm minimization.


title:
Orientation Determination in Single Particle X-ray Coherent Diffraction
  Imaging Experiments

abstract:
  Single particle diffraction imaging experiments at free-electron lasers (FEL)
have a great potential for structure determination of reproducible biological
specimens that can not be crystallized. One of the challenges in processing the
data from such an experiment is to determine correct orientation of each
diffraction pattern from samples randomly injected in the FEL beam. We propose
an algorithm (see also O. Yefanov et al., Photon Science - HASYLAB Annual
Report 2010) that can solve this problem and can be applied to samples from
tens of nanometers to microns in size, measured with sub-nanometer resolution
in the presence of noise. This is achieved by the simultaneous analysis of a
large number of diffraction patterns corresponding to different orientations of
the particles. The algorithms efficiency is demonstrated for two biological
samples, an artificial protein structure without any symmetry and a virus with
icosahedral symmetry. Both structures are few tens of nanometers in size and
consist of more than 100 000 non-hydrogen atoms. More than 10 000 diffraction
patterns with Poisson noise were simulated and analyzed for each structure. Our
simulations indicate the possibility to achieve resolution of about 3.3 {\AA}
at 3 {\AA} wavelength and incoming flux of 10^{12} photons per pulse focused to
100\times 100 nm^2.


title:
Bound states and scattering coefficients of self-adjoint Hamiltonians
  with a mass jump

abstract:
  Physical self-adjoint extensions and their spectra of the simplest
one-dimensional Hamiltonian operator in which the mass is constant except for a
finite jump at one point of the real axis are correctly found. Some
self-adjoint extensions are used to model different kinds of semiconductor
heterojunctions within the effective-mass approximation. Their properties and
relation to different boundary conditions on envelope wave functions are
studied. The limiting case of equal masses (with no mass jump) are reviewed.


title: Wolff's Problem of Ideals in the Multiplier Algebra on Dirichlet space

abstract:
  We establish an analogue of Wolff's theorem on ideals in
$H^{\infty}(\mathbb{D})$ for the multiplier algebra of Dirichlet space.


title: Obstructions To Classically Simulating The Quantum Adiabatic Algorithm

abstract:
  We consider the adiabatic quantum algorithm for systems with "no sign
problem", such as the transverse field Ising mode, and analyze the
equilibration time for quantum Monte Carlo (QMC) on these systems. We ask: if
the spectral gap is only inverse polynomially small, will equilibration methods
based on slowly changing the Hamiltonian parameters in the QMC simulation
succeed in a polynomial time? We show that this is not true, by constructing
counter-examples. Some examples are Hamiltonians where the space of
configurations where the wavefunction has non-negligible amplitude has a
nontrivial fundamental group, causing the space of trajectories in imaginary
time to break into disconnected components, with only negligible probability
outside these components. For the simplest example we give with an abelian
fundamental group, QMC does not equilibrate but still solves the optimization
problem. More severe effects leading to failure to solve the optimization can
occur when the fundamental group is a free group on two generators. Other
examples where QMC fails have a trivial fundamental group, but still use ideas
from topology relating group presentations to simplicial complexes. We define
gadgets to realize these Hamiltonians as the effective low-energy dynamics of a
transverse field Ising model. We present some analytic results on equilibration
times which may be of some independent interest in the theory of equilibration
of Markov chains. Conversely, we show that a small spectral gap implies slow
equilibration at low temperature for some initial conditions and for a natural
choice of local QMC updates.


title:
Invisible Flow Watermarks for Channels with Dependent Substitution,
  Deletion, and Bursty Insertion Errors

abstract:
  Flow watermarks efficiently link packet flows in a network in order to thwart
various attacks such as stepping stones. We study the problem of designing good
flow watermarks. Earlier flow watermarking schemes mostly considered
substitution errors, neglecting the effects of packet insertions and deletions
that commonly happen within a network. More recent schemes consider packet
deletions but often at the expense of the watermark visibility. We present an
invisible flow watermarking scheme capable of enduring a large number of packet
losses and insertions. To maintain invisibility, our scheme uses quantization
index modulation (QIM) to embed the watermark into inter-packet delays, as
opposed to time intervals including many packets. As the watermark is injected
within individual packets, packet losses and insertions may lead to watermark
desynchronization and substitution errors. To address this issue, we add a
layer of error-correction coding to our scheme. Experimental results on both
synthetic and real network traces demonstrate that our scheme is robust to
network jitter, packet drops and splits, while remaining invisible to an
attacker.


title:
Periodic and rapid decay rank two self-adjoint commuting differential
  operators

abstract:
  Self-adjoint rank two commuting ordinary differential operators are studied
in this paper. Such operators with trigonometric, elliptic and rapid decay
coefficients corresponding to hyperelliptic spectral curves are constructed.
Some problems related to the Lame operator and rank two solutions of soliton
equations are discussed.


title:
The skew growth functions $N_{M, \mathrm{deg}}(t)$ for the monoid of
  type $\mathrm{B_{ii}}$ and others

abstract:
  Let $M$ be a positive homogeneously presented cancellative monoid ${< L \mid
R >}_{mo}$ equipped with the degree map $\deg:M \to \Z_{\ge0}$ defined by
assigning to each equivalence class of words the length of the words, and let
$P_{M, \deg}(t):= \sum_{u \in\ M}t^{\deg(u)}$ be its generating series, called
the growth function. If $M$ satisfies the condition that any subset $J$ of
$I_0$ ($:=$ the image of the set $L$ in $M$) admits either the least right
common multiple $\Delta_{J}$ or no common multiple in $M$, then the inversion
function $P_{M, \deg}(t)^{-1}$ is given by the polynomial $\sum_{J \subset
I_{0}}(-1)^{#J} t^{\deg(\Delta_{J})}$, where the summation index $J$ runs over
all subsets of $I_0$ whose least right common multiple exists. Since a monoid
$M$ generally may not admit the least right common multiple $\Delta_{J}$ for a
given subset $J$ of it, if we attempt to generalize the formula, the
consideration to obtain the above formula is invalid. To resolve this
obstruction, we will examine the set $\mathrm{mcm}(J)$ of minimal common right
multiples of $J$. Then, we need to introduce a concept of a tower of minimal
common multiples of elements of $M$ and denote the set of all the towers in $M$
by $\mathrm{Tmcm}(M)$. Considering the structure of the set $\mathrm{Tmcm}(M)$,
K. Saito has proved the inversion formula \[ P_{M,\deg}(t). N_{M,\deg}(t)=1, \]
where the second factor in LHS is a suitably signed generating series \[
N_{M,\deg}(t):= 1 + \sum_{T\in
\mathrm{Tmcm}(M)}(-1)^{#J_1+...+#J_{n}-n+1}\sum_{\Delta\in \mathrm{mcm}(J_n)}
t^{\deg(\Delta)}, \] called the skew growth function. In this article, we
present several explicit calculations of examples of the skew growth functions
for the monoid of type $\mathrm{B_{ii}}$ and others whose towers do not stop on
the first stage $J_1$.


title: Coulomb gauge model for hidden charm tetraquarks

abstract:
  The spectrum of tetraquark states with hidden charm is studied within an
effective QCD Coulomb gauge Hamiltonian approach. Of the four independent color
schemes, two are investigated, the $(q\bar{c})_1(c\bar{q})_1$ singlet-singlet
(molecule) and the $(qc)_3(\bar{q}\bar{c})_3$ triplet-triplet (diquark), for
selected $J^{PC}$ states using a variational method. The predicted masses of
triplet-triplet tetraquarks are roughly a GeV heavier than the singlet-singlet
states. There is also an interesting flavor dependence with
$(q\bar{q})_1(c\bar{c}_1)$ states about half a GeV lighter than
$(q\bar{c})_1(\bar{q}c)_1$. The lightest $1^{++}$ and $1^{--}$ predictions are
in agreement with the observed X(3872) and Y(4008) masses, respectively,
suggesting they both have a $\omega J/ \psi$ rather than $D^*\bar D^*$
molecular type structure. This is consistent with observed $X$, $Y$ decays to
$\pi^\pm J/ \psi$ and not $D^*\bar D^*$ .


title:
aTmcam: A Simple Atmospheric Transmission Monitoring Camera For Sub 1%
  Photometric Precision

abstract:
  Traditional color and airmass corrections can typically achieve ~0.02 mag
precision in photometric observing conditions. A major limiting factor is the
variability in atmospheric throughput, which changes on timescales of less than
a night. We present preliminary results for a system to monitor the throughput
of the atmosphere, which should enable photometric precision when coupled to
more traditional techniques of less than 1% in photometric conditions. The
system, aTmCam, consists of a set of imagers each with a narrow-band filter
that monitors the brightness of suitable standard stars. Each narrowband filter
is selected to monitor a different wavelength region of the atmospheric
transmission, including regions dominated by the precipitable water absorption
and aerosol scattering. We have built a prototype system to test the notion
that an atmospheric model derived from a few color indices measurements can be
an accurate representation of the true atmospheric transmission. We have
measured the atmospheric transmission with both narrowband photometric
measurements and spec- troscopic measurements; we show that the narrowband
imaging approach can predict the changes in the throughput of the atmosphere to
better than ~10% across a broad wavelength range, so as to achieve photometric
precision less than 0.01 mag.


title: Nematicity driven by hybridization in iron-based superconductors

abstract:
  In this paper we study an effective model for the normal state of iron-based
superconductors. It has separate, but interacting itinerant and localized
degrees of freedom, originating from the d_xz and d_yz, and from d_xy iron
orbitals respectively. At low temperatures, below a mean-field phase
transition, these different states condense together in an excitonic order
parameter. We show that at even lower temperature, after another phase
transition, this ordered state can spontaneously break the C_4 lattice symmetry
and become nematic. We propose this mechanism as an explanation of the tendency
towards nematicity observed in several iron-based compounds.


title: Exploring QCD phase diagram at vanishing baryon density on the lattice

abstract:
  I report on the current status of QCD phase diagram at vanishing baryon
density. I focus on the QCD phase diagram with three degenerate quark flavor
using Highly Improved Staggered Quarks on $N_{\tau}=6$ lattices. No evidence of
a first order phase transition in the pion mass window of $80\lesssim m_{\pi}
\lesssim 230 $MeV is found. The pion mass at the critical point where the
chiral first order phase transition ends is estimated to be $m^c_{\pi} \lesssim
45$ MeV.


title:
The smallest part of the generic partition of the nilpotent commutator
  of a nilpotent matrix

abstract:
  Let $k$ be an infinite field. Fix a Jordan nilpotent $n$ by $n$ matrix $B =
J_P$ with entries in $k$ and associated Jordan type $P$. Let $Q(P)$ be the
Jordan type of a generic nilpotent matrix commuting with $B$. In this paper, we
use the combinatorics of a poset associated to the partition $P$, to give an
explicit formula for the smallest part of $Q(P)$, which is independent of the
characteristic of $k$. This, in particular, leads to a complete description of
$Q(P)$ when it has at most three parts.


title:
On the Weak Lefschetz Property for Artinian Gorenstein algebras of
  codimension three

abstract:
  We study the problem of whether an arbitrary codimension three graded
artinian Gorenstein algebra has the Weak Lefschetz Property. We reduce this
problem to checking whether it holds for all compressed Gorenstein algebras of
odd socle degree. In the first open case, namely Hilbert function
(1,3,6,6,3,1), we give a complete answer in every characteristic by translating
the problem to one of studying geometric aspects of certain morphisms from
$\mathbb P^2$ to $\mathbb P^3$, and Hesse configurations in $\mathbb P^2$.


title:
Bayesian inference of inaccuracies in radiation transport physics from
  inertial confinement fusion experiments

abstract:
  First principles microphysics models are essential to the design and analysis
of high energy density physics experiments. Using experimental data to
investigate the underlying physics is also essential, particularly when
simulations and experiments are not consistent with each other. This is a
difficult task, due to the large number of physical models that play a role,
and due to the complex (and as a result, noisy) nature of the experiments. This
results in a large number of parameters that make any inference a daunting
task; it is also very important to consistently treat both experimental and
prior understanding of the problem. In this paper we present a Bayesian method
that includes both these effects, and allows the inference of a set of
modifiers which have been constructed to give information about microphysics
models from experimental data. We pay particular attention to radiation
transport models. The inference takes into account a large set of experimental
parameters and an estimate of the prior knowledge through a modified $\chi^{2}$
function, which is minimised using an efficient genetic algorithm. Both factors
play an essential role in our analysis. We find that although there is evidence
of inaccuracies in off-line calculations of X ray drive intensity and Ge $L$
shell absorption, modifications to radiation transport are unable to reconcile
differences between 1D HYDRA simulations and the experiment.

categories: physics.plasm-ph physics.atom-ph physics.data-an stat.AP


title: Combinatorial Applications of M\"obius Inversion

abstract:
  In important work on the parity of the partition function, Ono related values
of the partition function to coefficients of a certain mock theta function
modulo 2. In this paper, we use M\"obius inversion to give analogous results
which relate several combinatorial functions via identities rather than
congruences.


title:
Development of a Bayesian method for the analysis of inertial
  confinement fusion experiments on the NIF

abstract:
  The complex nature of inertial confinement fusion (ICF) experiments results
in a very large number of experimental parameters that are only known with
limited reliability. These parameters, combined with the myriad physical models
that govern target evolution, make the reliable extraction of physics from
experimental campaigns very difficult. We develop an inference method that
allows all important experimental parameters, and previous knowledge, to be
taken into account when investigating underlying microphysics models. The
result is framed as a modified $\chi^{2}$ analysis which is easy to implement
in existing analyses, and quite portable. We present a first application to a
recent convergent ablator experiment performed at the NIF, and investigate the
effect of variations in all physical dimensions of the target (very difficult
to do using other methods). We show that for well characterised targets in
which dimensions vary at the 0.5% level there is little effect, but 3%
variations change the results of inferences dramatically. Our Bayesian method
allows particular inference results to be associated with prior errors in
microphysics models; in our example, tuning the carbon opacity to match
experimental data (i.e., ignoring prior knowledge) is equivalent to an assumed
prior error of 400% in the tabop opacity tables. This large error is
unreasonable, underlining the importance of including prior knowledge in the
analysis of these experiments.


title: Crystal structures of spin-Jahn-Teller ordered MgCr_2O_4 and ZnCr_2O_4

abstract:
  Magnetic ordering in the geometrically frustrated magnetic oxide spinels
MgCr_2O_4 and ZnCr_2O_4 is accompanied by a structural change that helps
relieve the frustration. Analysis of high-resolution synchrotron X-ray
scattering reveals that the low-temperature structures are well described by a
two-phase model of tetragonal I4_1/amd and orthorhombic Fddd symmetries. The
Cr_4 tetrahedra of the pyrochlore lattice are distorted at these
low-temperatures, with the Fddd phase displaying larger distortions than the
I4_1/amd phase. The spin-Jahn-Teller distortion is approximately one order of
magnitude smaller than is observed in first-order Jahn-Teller spinels such as
NiCr_2O_4 and CuCr_2O_4. In analogy with NiCr_2O_4 and CuCr_2O_4, we further
suggest that the precise nature of magnetic ordering can itself provide a
second driving force for structural change.


title: Resonant production of spin-3/2 color octet electron at the LHeC

abstract:
  In this work, we investigated resonant production of spin-3/2 color octet
electron at the Large Hadron electron Collider (LHeC). Signal and background
analysis have been performed and discovery, observation and exclusion limits
are determined for spin 3/2 color octet electron masses. Reachable values of
the compositeness scale are presented as a function of the spin-3/2 color octet
electron masses.


title:
Effect of in-situ deposition of Mg adatoms on spin relaxation in
  graphene

abstract:
  We have systematically introduced charged impurity scatterers in the form of
Mg adsorbates to exfoliated single layer graphene and observe little variation
of the spin relaxation times despite pronounced changes in the charge transport
behavior. All measurements are performed on non-local graphene tunneling spin
valves exposed in-situ to Mg adatoms, thus systematically introducing
atomic-scale charged impurity scattering. While charge transport properties
exhibit decreased mobility and decreased momentum scattering times, the
observed spin lifetimes are not significantly affected indicating that charged
impurity scattering is inconsequential in the present regime of spin relaxation
times.


title:
Unbiased Estimators for the Parameters of the Binomial and Multinomial
  Distributions

abstract:
  The exact expression is derived for the expected value, $< {p_i}> $, for the
parameter for any bin $i$ of a histogram following a multinomial distribution
derived by sorting $N$ observations into bins of $B$ classes, if $n_i$ of the
observations are found to be sorted into bin $i$. This expected value is found
to be $ < {p_i}> = \frac {n_i + 1} {N + B}$. The expected value for the
variance is found to be $\frac{< p_i > (1-< p_i >)}{N+B+1}$. A general
expression is derived to determine $< {p_i}^z > $ for arbitrary values of $B$
and $z$. These expressions hold provided there is no \emph{a priori} reason for
$p_i$ associated with any bin to have a value that is exactly equal to 0. For
the particular case of the binomial distribution (B=2), these estimators are
tested by examining how often the value of $p_{true}$, the value which is used
to generate sets of pseudo-random binomial variates, falls within 1.96
estimated standard deviations of the estimated value $< p >$. When compared
with the results of identical, earlier reported tests for small sample sizes,
the unbiased estimators derived here predictably outperform
\emph{asymptotically} unbiased estimators


title:
Spherically symmetric models: separating expansion from contraction in
  models with anisotropic pressures

abstract:
  We investigate spherically symmetric spacetimes with an anisotropic fluid and
discuss the existence and stability of a dividing shell separating expanding
and collapsing regions. We find that the dividing shell is defined by a
relation between the pressure gradients, both isotropic and anisotropic, and
the strength of the fields induced by the Misner-Sharpe mass inside the
separating shell and by the pressure fluxes. This balance is a generalization
of the Tolman-Oppenheimer- Volkoff equilibrium condition which defines a local
equilibrium condition, but conveys also a non- local character given the
definition of the Misner-Sharpe mass. We present a particular solution with
dust and radiation that provides an illustration of our results.


title: Integration of the Ferromagnetic Insulator EuO onto Graphene

abstract:
  We have demonstrated the deposition of EuO films on graphene by reactive
molecular beam epitaxy in a special adsorption-controlled and oxygen-limited
regime, which is a critical advance toward the realization of the exchange
proximity interaction (EPI). It has been predicted that when the ferromagnetic
insulator (FMI) EuO is brought into contact with graphene, an overlap of
electronic wavefunctions at the FMI/graphene interface can induce a large spin
splitting inside the graphene. Experimental realization of this effect could
lead to new routes for spin manipulation, which is a necessary requirement for
a functional spin transistor. Furthermore, EPI could lead to novel spintronic
behavior such as controllable magnetoresistance, gate tunable exchange bias,
and quantized anomalous Hall effect. However, experimentally, EuO has not yet
been integrated onto graphene. Here we report the successful growth of high
quality crystalline EuO on highly-oriented pyrolytic graphite (HOPG) and
single-layer graphene. The epitaxial EuO layers have (001) orientation and do
not induce an observable D peak (defect) in the Raman spectra. Magneto-optic
measurements indicate ferromagnetism with Curie temperature of 69 K, which is
the value for bulk EuO. Transport measurements on exfoliated graphene before
and after EuO deposition indicate only a slight decrease in mobility.


title: The Regularity of the Conductor

abstract:
  We bound the Castelnuovo-Mumford regularity and syzygies of the ideal of the
singular set of a plane curve, and more generally of the conductor scheme of
certain projectively Gorenstein varieties.


title:
Preparation of Schr\"{o}dinger cat states of a cavity field via coupling
  to a superconducting charge qubit

abstract:
  We extend the approach of Ref. [Yu-xi Liu, L. F. Wei, and F. Nori, Europhys.
Lett. 67, 941 (2004)] for preparing superposition states of a cavity field
interacting with a superconducting charge qubit. We study effects of the
nonlinearity on the creation of such states. We show that the main contribution
of nonlinear effects is to shorten the time necessary to build the
superposition.


title:
Enumeration Based Search Algorithm For Finding A Regular Bi-partite
  Graph Of Maximum Attainable Girth For Specified Degree And Number Of Vertices

abstract:
  We introduce a search problem for finding a regular bi-partite graph of
maximum attainable girth for specified degree and number of vertices, by
restricting the search space using a series of mathematically rigourous
arguments from [1] and [2]. The goal of this paper is to derive the enumeration
search algorithm for finding a girth maximum (m, r) BTU, which is notation for
regular partite graph that has been introduced in [1], using the optimal
partition results from [2] as a starting point, and also understand the
structure of the search space and the computational complexity of the
algorithm.


title: Analysis Of The Girth For Regular Bi-partite Graphs With Degree 3

abstract:
  The goal of this paper is to derive the detailed description of the
Enumeration Based Search Algorithm from the high level description provided in
[16], analyze the experimental results from our implementation of the
Enumeration Based Search Algorithm for finding a regular bi-partite graph of
degree 3, and compare it with known results from the available literature. We
show that the values of m for a given girth g for (m, 3) BTUs are within the
known mathematical bounds for regular bi-partitite graphs from the available
literature.


title: From operator categories to topological operads

abstract:
  In this paper we introduce the notion of an operator category and two
different models for homotopy theory of $\infty$-operads over an operator
category -- one of which extends Lurie's theory of $\infty$-operads, the other
of which is completely new, even in the commutative setting. We define perfect
operator categories, and we describe a category $\Lambda(\Phi)$ attached to a
perfect operator category $\Phi$ that provides Segal maps. We define a wreath
product of operator categories and a form of the Boardman--Vogt tensor product
that lies over it. We then give examples of operator categories that provide
universal properties for the operads $A_n$ and $E_n$ ($1\leq n\leq +\infty$),
as well as a collection of new examples.


title:
Atomistic origin of doping-enhanced rapid crystallization in Ag-doped
  Ge-Sb-Te alloys: a joint experimental and theoretical study

abstract:
  We have applied extended X-ray absorption fine structure (EXAFS) analyses and
ab-initio molecular dynamics (AIMD) simulations to study the atomic structure
of Ag-doped (up to 42%) Ge1Sb2Te4 alloys. Analysis of the models that are
consistent with the EXAFS experiment reveals that the Ge environment is
significantly modified by Ag doping whereas those of Sb and Te are barely
affected (except for high Ag concentrations), and suggests that Ag prefers
bonding with Te to Ge or Sb. Doping with Ag promotes the conversion of
tetrahedral Ge sites to octahedral Ge sites and enhances the speed of
crystallization of Ge-Sb-Te (GST) alloys as evidenced directly from the MD
simulations. Our study shed light on the atomistic mechanism of rapid
crystallization of GST alloys enhanced by Ag doping.


title:
Vapor-Solid Growth of High Optical Quality MoS2 Monolayers With
  Near-Unity Valley Polarization

abstract:
  Monolayers of transition metal dichalcogenides (TMDCs) are atomically thin
direct-gap semiconductors with potential applications in nanoelectronics,
optoelectronics, and electrochemical sensing. Recent theoretical and
experimental efforts suggest that they are ideal systems for exploiting the
valley degrees of freedom of Bloch electrons. For example, Dirac valley
polarization has been demonstrated in mechanically exfoliated monolayer MoS2
samples by polarization-resolved photoluminescence, although polarization has
rarely been seen at room temperature. Here we report a new method for
synthesizing high optical quality monolayer MoS2 single crystals up to 25
microns in size on a variety of standard insulating substrates (SiO2, sapphire
and glass) using a catalyst-free vapor-solid growth mechanism. The technique is
simple and reliable, and the optical quality of the crystals is extremely high,
as demonstrated by the fact that the valley polarization approaches unity at 30
K and persists at 35% even at room temperature, suggesting a virtual absence of
defects. This will allow greatly improved optoelectronic TMDC monolayer devices
to be fabricated and studied routinely.


title: Does Silicene on Ag(111) Have a Dirac Cone?

abstract:
  We investigate the currently debated issue of the existence of the Dirac cone
in silicene on an Ag(111) surface, using first-principles calculations based on
density functional theory to obtain the band structure. By unfolding the band
structure in the Brillouin zone of a supercell to that of a primitive cell,
followed by projecting onto Ag and silicene subsystems, we demonstrate that the
Dirac cone in silicene on Ag(111) is destroyed. Our results clearly indicate
that the linear dispersions observed in both angular-resolved photoemission
spectroscopy (ARPES) [P. Vogt et al, Phys. Rev. Lett. 108, 155501 (2012)] and
scanning tunneling spectroscopy (STS) [L. Chen et al, Phys. Rev. Lett. 109,
056804 (2012)] come from the Ag substrate and not from silicene.


title:
Weakly Asymmetric Non-Simple Exclusion Process and the
  Kardar-Parisi-Zhang Equation

abstract:
  We analyze a class of non-simple exclusion processes and the corresponding
growth models by generalizing Gaertners Cole-Hopf transformation. We identify
the main non-linearity and eliminate it by imposing a gradient type condition.
For hopping range at most 3, using the generalized transformation, we prove the
convergence of the exclusion process toward the Kardar-Parisi-Zhang (KPZ)
equation. This is the first universality result concerning interacting particle
systems in the context of KPZ universality class. While this class of exclusion
processes are not explicitly solvable, we obtain the exact one-point limiting
distribution for the step initial condition by using the previous result of
Amir et al. (2011) and our convergence result.


title:
Path-integral simulations with fermionic and bosonic reservoirs:
  Transport and dissipation in molecular electronic junctions

abstract:
  We expand iterative numerically-exact influence functional path-integral
tools and present a method capable of following the nonequilibrium time
evolution of subsystems coupled to multiple bosonic and fermionic reservoirs
simultaneously. Using this method, we study the real-time dynamics of charge
transfer and vibrational mode excitation in an electron conducting molecular
junction. We focus on nonequilibrium vibrational effects, particularly, the
development of vibrational instability in a current-rectifying junction. Our
simulations are performed by assuming large molecular vibrational anharmonicity
(or low temperature). This allows us to truncate the molecular vibrational mode
to include only a two-state system. Exact numerical results are compared to
perturbative Master equation calculations demonstrating an excellent agreement
in the weak electron-phonon coupling regime. Significant deviations take place
only at strong coupling. Our simulations allow us to quantify the contribution
of different transport mechanisms, coherent dynamics and inelastic transport,
in the overall charge current. This is done by studying two model variants: The
first admits inelastic electron transmission only, while the second one allows
for both coherent and incoherent pathways.


title: Probabilistic Non-Local Means

abstract:
  In this paper, we propose a so-called probabilistic non-local means (PNLM)
method for image denoising. Our main contributions are: 1) we point out defects
of the weight function used in the classic NLM; 2) we successfully derive all
theoretical statistics of patch-wise differences for Gaussian noise; and 3) we
employ this prior information and formulate the probabilistic weights truly
reflecting the similarity between two noisy patches. The probabilistic nature
of the new weight function also provides a theoretical basis to choose
thresholds rejecting dissimilar patches for fast computations. Our simulation
results indicate the PNLM outperforms the classic NLM and many NLM recent
variants in terms of peak signal noise ratio (PSNR) and structural similarity
(SSIM) index. Encouraging improvements are also found when we replace the NLM
weights with the probabilistic weights in tested NLM variants.


title:
Strongly magnetized electron degenerate gas: Highly super-Chandrasekhar
  white dwarfs

abstract:
  We consider a relativistic, degenerate, electron gas under the influence of a
strong magnetic field, which describes magnetized white dwarfs. Landau
quantization changes the density of states available to the electrons, thus
modifying the underlying equation of state. We obtain the mass-radius relations
for such white dwarfs and show that it is possible to have magnetized white
dwarfs with a mass significantly greater than the Chandrasekhar limit in the
range 2.3 - 2.6 M_sun. Recent observations of peculiar type Ia supernovae - SN
2006gz, SN 2007if, SN 2009dc, SN 2003fg - seem to suggest
super-Chandrasekhar-mass white dwarfs with masses up to 2.4 - 2.8 M_sun, as
their most likely progenitors and interestingly our results lie within the
observational limits.


title: Multiband Vector Plasmonic Lattice Solitons

abstract:
  We predict multiband vector Plasmonic Lattice Solitons (PLSs) in
metal-dielectric waveguide arrays, in both focusing and defocusing
nonlinearities. Such vector solitons consist of two components originating from
different transmission bands. By simulating the full nonlinear Maxwell
equations (MEs), we demonstrate the diffractionless propagation of vector PLSs
and their discrete diffraction when only one component is present. Their
subwavelength size characteristics and the influences of metallic losses are
also studied.


title:
Call-by-Value and Call-by-Name Dual Calculi with Inductive and
  Coinductive Types

abstract:
  This paper extends the dual calculus with inductive types and coinductive
types. The paper first introduces a non-deterministic dual calculus with
inductive and coinductive types. Besides the same duality of the original dual
calculus, it has the duality of inductive and coinductive types, that is, the
duality of terms and coterms for inductive and coinductive types, and the
duality of their reduction rules. Its strong normalization is also proved,
which is shown by translating it into a second-order dual calculus. The strong
normalization of the second-order dual calculus is proved by translating it
into the second-order symmetric lambda calculus. This paper then introduces a
call-by-value system and a call-by-name system of the dual calculus with
inductive and coinductive types, and shows the duality of call-by-value and
call-by-name, their Church-Rosser properties, and their strong normalization.
Their strong normalization is proved by translating them into the
non-deterministic dual calculus with inductive and coinductive types.