title:
The Bifurcated Age-Metallicity Relation of Milky Way Globular Clusters
  and its Implications For the Accretion History of the Galaxy

abstract:
  We use recently derived ages for 61 Milky Way (MW) globular clusters (GCs) to
show that their age-metallicity relation (AMR) can be divided into two
distinct, parallel sequences at [Fe/H] $\ga -1.8$. Approximately one-third of
the clusters form an offset sequence that spans the full range in age ($\sim
10.5$--13 Gyr), but is more metal rich at a given age by $\sim 0.6$ dex in
[Fe/H]. All but one of the clusters in the offset sequence show orbital
properties that are consistent with membership in the MW disk. They are not
simply the most metal-rich GCs, which have long been known to have disk-like
kinematics, but they are the most metal-rich clusters at all ages. The slope of
the mass-metallicity relation (MMR) for galaxies implies that the offset in
metallicity of the two branches of the AMR corresponds to a mass decrement of 2
dex, suggesting host galaxy masses of $M_{*} \sim 10^{7-8} \msol$ for GCs that
belong to the more metal-poor AMR. We suggest that the metal-rich branch of the
AMR consists of clusters that formed in-situ in the disk, while the metal-poor
GCs were formed in relatively low-mass (dwarf) galaxies and later accreted by
the MW. The observed AMR of MW disk stars, and of the LMC, SMC and WLM dwarf
galaxies are shown to be consistent with this interpretation, and the relative
distribution of implied progenitor masses for the halo GC clusters is in
excellent agreement with the MW subhalo mass function predicted by simulations.
A notable implication of the bifurcated AMR, is that the identical mean ages
and spread in ages, for the metal rich and metal poor GCs are difficult to
reconcile with an in-situ formation for the latter population.


title:
Substellar Objects in Nearby Young Clusters VII: The substellar mass
  function revisited

abstract:
  The abundance of brown dwarfs (BDs) in young clusters is a diagnostic of star
formation theory. Here we revisit the issue of determining the substellar
initial mass function (IMF), based on a comparison between NGC1333 and IC348,
two clusters in the Perseus star-forming region. We derive their mass
distributions for a range of model isochrones, varying distances, extinction
laws and ages, with comprehensive assessments of the uncertainties. We find
that the choice of isochrone and other parameters have significant effects on
the results, thus we caution against comparing IMFs obtained using different
approaches. For NGC1333, we find that the star/BD ratio R is between 1.9 and
2.4, for all plausible scenarios, consistent with our previous work. For IC348,
R is between 2.9 and 4.0, suggesting that previous studies have overestimated
this value. Thus, the star forming process generates about 2.5-5 substellar
objects per 10 stars. The derived star/BD ratios correspond to a slope of the
power-law mass function of alpha=0.7-1.0 for the 0.03-1.0Msol mass range. The
median mass in these clusters - the typical stellar mass - is between
0.13-0.30Msol. Assuming that NGC1333 is at a shorter distance than IC348, we
find a significant difference in the cumulative distribution of masses between
the two clusters, resulting from an overabundance of very low mass objects in
NGC1333. Gaia astrometry will constrain the cluster distances better and will
lead to a more definitive conclusion. Furthermore, ratio R is somewhat larger
in IC348 compared with NGC1333, although this difference is still within the
margins of error. Our results indicate that environments with higher object
density may produce a larger fraction of very low mass objects, in line with
predictions for brown dwarf formation through gravitational fragmentation of
filaments falling into a cluster potential.


title: Discovery of Super-Thin Disks in Nearby Edge-on Spiral Galaxies

abstract:
  We report the identification of a super-thin disk (h_z~60 pc) in the edge-on
spiral galaxy NGC 891. This component is only apparent after we perform a
physically motivated attenuation correction, based on detailed radiation
transfer models, to our sub-arcsecond resolution near-infrared imaging. In
addition to the super-thin disk, we are also find several structural features
near the center of NGC 891, including an inner disk truncation at ~3 kpc. Inner
disk truncations may be commonplace among massive spiral galaxies, possibly due
to the effects of instabilities, such as bars. Having successfully demonstrated
our methods, we are poised to apply them to a small sample of nearby edge-on
galaxies, consisting both of massive and low-mass spirals.


title: Signatures of Dark Matter Scattering Inelastically Off Nuclei

abstract:
  Direct dark matter detection focuses on elastic scattering of dark matter
particles off nuclei. In this study, we explore inelastic scattering where the
nucleus is excited to a low-lying state of 10-100 keV, with subsequent prompt
de-excitation. We calculate the inelastic structure factors for the odd-mass
xenon isotopes based on state-of-the-art large-scale shell-model calculations
with chiral effective field theory WIMP-nucleon currents. For these cases, we
find that the inelastic channel is comparable to or can dominate the elastic
channel for momentum transfers around 150 MeV. We calculate the inelastic
recoil spectra in the standard halo model, compare these to the elastic case,
and discuss the expected signatures in a xenon detector, along with
implications for existing and future experiments. The combined information from
elastic and inelastic scattering will allow to determine the dominant
interaction channel within one experiment. In addition, the two channels probe
different regions of the dark matter velocity distribution and can provide
insight into the dark halo structure. The allowed recoil energy domain and the
recoil energy at which the integrated inelastic rates start to dominate the
elastic channel depend on the mass of the dark matter particle, thus providing
a potential handle to constrain its mass.


title: Truncated hierarchical preconditioning for the stochastic Galerkin FEM

abstract:
  Stochastic Galerkin finite element discretizations of partial differential
equations with coefficients characterized by arbitrary distributions lead, in
general, to fully block dense linear systems. We propose two novel strategies
for constructing preconditioners for these systems to be used with Krylov
subspace iterative solvers. In particular, we present a variation on of the
hierarchical Schur complement preconditioner, developed recently by the
authors, and an adaptation of the symmetric block Gauss-Seidel method. Both
preconditioners take advantage of the hierarchical structure of global
stochastic Galerkin matrices, and also, when applicable, of the decay of the
norms of the stiffness matrices obtained from the polynomial chaos expansion of
the coefficients. This decay allows to truncate the matrix-vector
multiplications in the action of the preconditioners. Also, throughout the
global matrix hierarchy, we approximate solves with certain submatrices by the
associated diagonal block solves. The preconditioners thus require only a
limited number of stiffness matrices obtained from the polynomial chaos
expansion of the coefficients, and a preconditioner for the diagonal blocks of
the global matrix. The performance is illustrated by numerical experiments.


title: Average methods and their applications in Differential Geometry I

abstract:
  In Minkowski geometry the metric features are based on a compact convex body
containing the origin in its interior. This body works as a unit ball with its
boundary formed by the unit vectors. Using one-homogeneous extension we have a
so-called Minkowski functional to measure the lenght of vectors. The half of
its square is called the energy function. Under some regularity conditions we
can introduce an average Euclidean inner product by integrating the Hessian
matrix of the energy function on the Minkowskian unit sphere. Changing the
origin in the interior of the body we have a collection of Minkowskian unit
balls together with Minkowski functionals depending on the base points. It is a
kind of special Finsler manifolds called a Funk space. Using the previous
method we can associate a Riemannian metric as the collections of the Euclidean
inner products belonging to different base points. We investigate this
procedure in case of Finsler manifolds in general. Central objects of the
associated Riemannian structure will be expressed in terms of the canonical
data of the Finsler space. We take one more step forward by introducing
associated Randers spaces by averaging of the vertical derivatives of the
Finslerian fundamental function. Such kind of perturbation will have a crucial
role when we apply the general results to Funk spaces together with some
contributions to Brickell's conjecture on Finsler manifolds with vanishing
curvature tensor $\mathbb{Q}$.


title: Quenching to unitarity: Quantum dynamics in a 3D Bose gas

abstract:
  We study the dynamics of a dilute Bose gas at zero temperature following a
sudden quench of the scattering length from a noninteracting Bose condensate to
unitarity (infinite scattering length). We apply three complementary approaches
to understand the momentum distribution and loss rates. First, using a
time-dependent variational ansatz for the many-body state, we calculate the
dynamics of the momentum distribution. Second, we demonstrate that, at short
times and large momenta compared to those set by the density, the physics can
be well understood within a simple, analytic two-body model. We derive a
quantitative prediction for the evolution of Tan's contact, which increases
linearly at short times. We also study the three-body losses at finite
densities. Consistent with experiments, we observe lifetimes which are long
compared to the dynamics of large momentum modes.


title: A Propositional Linear Time Logic with Time Flow Isomorphic to \omega^2

abstract:
  Primarily guided with the idea to express zero-time transitions by means of
temporal propositional language, we have developed a temporal logic where the
time flow is isomorphic to ordinal $\omega^2$ (concatenation of $\omega$ copies
of $\omega$). If we think of $\omega^2$ as lexicographically ordered
$\omega\times \omega$, then any particular zero-time transition can be
represented by states whose indices are all elements of some
$\{n\}\times\omega$. In order to express non-infinitesimal transitions, we have
introduced a new unary temporal operator $[\omega] $ ($\omega$-jump), whose
effect on the time flow is the same as the effect of $\alpha\mapsto
\alpha+\omega$ in $\omega^2$. In terms of lexicographically ordered
$\omega\times \omega$, $[\omega] \phi$ is satisfied in $\ < i,j\ >$-th time
instant iff $\phi$ is satisfied in $\ < i+1,0\ >$-th time instant. Moreover, in
order to formally capture the natural semantics of the until operator $\mathtt
U$, we have introduced a local variant $\mathtt u$ of the until operator. More
precisely, $\phi\,\mathtt u \psi$ is satisfied in $\ < i,j\ >$-th time instant
iff $\psi$ is satisfied in $\ < i,j+k\ >$-th time instant for some nonnegative
integer $k$, and $\phi$ is satisfied in $\ < i,j+l\ >$-th time instant for all
$0\leqslant l<k$. As in many of our previous publications, the leitmotif is the
usage of infinitary inference rules in order to achieve the strong
completeness.


title:
The 2:3:6 QPO structure in GRS 1915+105 and cubic subharmonics in the
  context of relativistic diskoseismology

abstract:
  We propose a simple toy model to explain the 2:3:6 QPO structure in GRS
1915+105 and, more generally, the 2:3 QPO structure in XTE J1550-564, GRO
J1655-40, and H 1743-322. The model exploits the onset of subharmonics in the
context of diskoseismology. We suggest that the observed frequencies may be the
consequence of a resonance between a fundamental g-mode and an unobservable
p-wave. The results include the prediction that, as better data become
available, a QPO with a frequency of twice the higher twin frequency and a
large quality factor will be observed in twin peak sources, as it might already
have been observed in the especially active GRS 1915+105.


title:
Unitarity constraints for Yukawa couplings in the two Higgs doublet
  model type III

abstract:
  Unitarity constraints for Yukawa couplings are considered in the Two Higgs
Doublet Model type III, by using a general expansion in partial waves for
fermionic scattering processes. Constraints over general Flavor Changing
Neutral Currents are found from that systematic, such bounds compete with those
coming from Lagrangian perturbativity requirement but are weaker than those
imposed from phenomenological processes and precision tests. Nevertheless, for
bounds based on unitarity the number of assumptions is the lowest among
phenomenological and theoretical limits. Indeed, these new theoretical
constraints are independent of scalar masses or mixing angles for this extended
Higgs sector, making them less model dependent.


title: The Enumeration of Permutations Avoiding 3124 and 4312

abstract:
  We find the generating function for the class of all permutations that avoid
the patterns 3124 and 4312 by showing that it is an inflation of the union of
two geometric grid classes.


title: Growth of human population in Australia, 1000-10,000 years BP

abstract:
  Close analysis of the published interpretation of the number of rock-shelter
sites in Australia provides further evidence that there was no intensification
in the growth of human population between 1000 and 10,000 years BP. An
alternative way of determining the time-dependent distribution of the size of
human population between 1000 and 10,000 years BP is discussed.


title:
Performance Analysis and Optimal Power Allocation for Linear Receivers
  Based on Superimposed Training

abstract:
  In this paper, we derive a performance comparison between two training-based
schemes for Multiple-Input Multiple-Output (MIMO) systems. The two schemes are
thetime-division multiplexing scheme and the recently proposed data-dependent
superimposed pilot scheme. For both schemes, a closed-form expressions for the
Bit Error Rate (BER) is provided. We also determine, for both schemes, the
optimal allocation of power between pilot and data that minimizes the BER.


title:
Quasi-sure Existence of Gaussian Rough Paths and Large Deviation
  Principles for Capacities

abstract:
  We construct a quasi-sure version (in the sense of Malliavin) of geometric
rough paths associated with a Gaussian process with long-time memory. As an
application we establish a large deviation principle (LDP) for capacities for
such Gaussian rough paths. Together with Lyons' universal limit theorem, our
results yield immediately the corresponding results for pathwise solutions to
stochastic differential equations driven by such Gaussian process in the sense
of rough paths. Moreover, our LDP result implies the result of Yoshida on the
LDP for capacities over the abstract Wiener space associated with such Gaussian
process.


title:
Gravitational Lens Models Based on Submillimeter Array Imaging of
  Herschel-selected Strongly Lensed Sub-millimeter Galaxies at z>1.5

abstract:
  Strong gravitational lenses are now being routinely discovered in wide-field
surveys at (sub)millimeter wavelengths. We present Submillimeter Array (SMA)
high-spatial resolution imaging and Gemini-South and Multiple Mirror Telescope
optical spectroscopy of strong lens candidates discovered in the two widest
extragalactic surveys conducted by the Herschel Space Observatory: the
Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS) and the Herschel
Multi-tiered Extragalactic Survey (HerMES). From a sample of 30 Herschel
sources with S_500>100 mJy, 21 are strongly lensed (multiply imaged), 4 are
moderately lensed (singly imaged), and the remainder require additional data to
determine their lensing status. We apply a visibility-plane lens modeling
technique to the SMA data to recover information about the masses of the lenses
as well as the intrinsic (i.e., unlensed) sizes (r_half) and far-infrared
luminosities (L_FIR) of the lensed submillimeter galaxies (SMGs). The sample of
lenses comprises primarily isolated massive galaxies, but includes some groups
and clusters as well. Several of the lenses are located at z_lens>0.7, a
redshift regime that is inaccessible to lens searches based on Sloan Digital
Sky Survey spectroscopy. The lensed SMGs are amplified by factors that are
significantly below statistical model predictions given the 500um flux
densities of our sample. We speculate that this may reflect a deficiency in our
understanding of the intrinsic sizes and luminosities of the brightest SMGs.
The lensed SMGs span nearly one decade in L_FIR (median L_FIR=7.9x10^12 L_sun)
and two decades in FIR luminosity surface density (median Sigma_FIR=6.0x10^11
L_sun kpc^-2). The strong lenses in this sample and others identified via
(sub-)mm surveys will provide a wealth of information regarding the
astrophysics of galaxy formation and evolution over a wide range in redshift.


title:
Bayesian Model Selection in Complex Linear Systems, as Illustrated in
  Genetic Association Studies

abstract:
  Motivated by examples from genetic association studies, this paper considers
the model selection problem in a general complex linear model system and in a
Bayesian framework. We discuss formulating model selection problems and
incorporating context-dependent {\it a priori} information through different
levels of prior specifications. We also derive analytic Bayes factors and their
approximations to facilitate model selection and discuss their theoretical and
computational properties. We demonstrate our Bayesian approach based on an
implemented Markov Chain Monte Carlo (MCMC) algorithm in simulations and a real
data application of mapping tissue-specific eQTLs. Our novel results on Bayes
factors provide a general framework to perform efficient model comparisons in
complex linear model systems.


title:
Elastic contribution to interaction of vortices in uniaxial
  superconductors

abstract:
  The stress caused by vortices in tetragonal superconductors contributes to
the intervortex interaction which depends on vortex orientation within the
crystal, on elastic moduli, and is attractive within certain angular regions
even in fields along the $c$ crystal axis. For sufficiently strong stress
dependence of the critical temperature, this contribution may result in
distortions of the hexagonal vortex lattice for $\bm H||\bm c$. In small fields
it leads to formation of a square vortex lattice with a fixed $H$ independent
spacing. This should be seen in the magnetization $M(H)$ as a discontinuous
jump of magnetization at the transition from the Meissner to mixed states.


title: Comment on Coherent Electron Cooling

abstract:
  We compare the method of Coherent Electron Cooling with Enhanced Optical
Cooling. According to our estimations the Enhanced Optical Cooling method
demonstrates some advantage for parameters of LHC.


title: Process tomography for unitary quantum channels

abstract:
  We study the number of measurements required for quantum process tomography
under prior information, such as a promise that the unknown channel is unitary.
We introduce the notion of an interactive observable and we show that any
unitary channel acting on a $d$-level quantum system can be uniquely identified
among all other channels (unitary or otherwise) with only $O(d^2)$ interactive
observables, as opposed to the $O(d^4)$ required for tomography of arbitrary
channels. This result generalizes, so that channels with at most $q$ Kraus
operators can be identified with only $O(qd^2)$ interactive observables. Slight
improvements can be obtained if we wish to identify such a channel only among
unital channels or among other channels with $q$ Kraus operators. These results
are proven via explicit construction of large subspaces of Hermitian matrices
with various conditions on rank, eigenvalues, and partial trace. Our
constructions are built upon various forms of totally nonsingular matrices.


title: Pluto's Atmosphere Does Not Collapse

abstract:
  Combining stellar occultation observations probing Pluto's atmosphere from
1988 to 2013 and models of energy balance between Pluto's surface and
atmosphere, we conclude that Pluto's atmosphere does not collapse at any point
in its 248-year orbit. The occultation results show an increasing atmospheric
pressure with time in the current epoch, a trend present only in models with a
high thermal inertia and a permanent N2 ice cap at Pluto's north rotational
pole.


title:
Printing out Particle Detectors with 3D-Printers, a Potentially
  Transformational Advance for HEP Instrumentation

abstract:
  This white paper suggests posing a "grand challenge" to the HEP
instrumentation community, i.e. the aggressive development of additive
manufacturing, also known as 3D-printing, for the production of particle
detectors in collaboration with industry. This notion is an outcome of
discussions within the instrumentation frontier group during the 2013 APS-DPF
Snowmass summer study conducted by the U.S. HEP community. Improvements of
current industrial 3D-printing capabilities by one to two orders of magnitude
in terms of printing resolution, speed, and object size together with
developing the ability to print composite materials could enable the production
of any desired 3D detector structure directly from a digital model. Current
industrial 3D-printing capabilities are briefly reviewed and contrasted with
capabilities desired for printing detectors for particle physics, with
micro-pattern gaseous detectors used as a first example. A significant impact
on industrial technology could be expected if HEP were to partner with industry
in taking on such a challenge.


title:
Phase diagram and water-like anomalies in core-softened
  shoulder-dumbbells system

abstract:
  Using molecular dynamics we studied the role of the anisotropy on the phase
boundary and on the anomalous behavior of 250 dimeric particles interacting by
a core-softened potential. This study led us to an unexpected result: the
introduction of a rather small anisotropy, quantified by the distance between
the particles inside each dimer, leads to the increase of the size of the
regions in the pressure-temperature phase diagram of anomalies when compared to
the isotropic monomeric case. However, as the anisotropy increases beyond a
threshold the anomalous regions shrinks. We found that this behavior can be
understood by decoupling the translational and non-translational kinetic energy
components into different translational and non-translational temperatures.


title: Bases as Coalgebras

abstract:
  The free algebra adjunction, between the category of algebras of a monad and
the underlying category, induces a comonad on the category of algebras. The
coalgebras of this comonad are the topic of study in this paper (following
earlier work). It is illustrated how such coalgebras-on-algebras can be
understood as bases, decomposing each element x into primitives elements from
which x can be reconstructed via the operations of the algebra. This holds in
particular for the free vector space monad, but also for other monads, like
powerset or distribution. For instance, continuous dcpos or stably continuous
frames, where each element is the join of the elements way below it, can be
described as such coalgebras. Further, it is shown how these
coalgebras-on-algebras give rise to a comonoid structure for copy and delete,
and thus to diagonalisation of endomaps like in linear algebra.


title: Excited quark production at a 100 TeV VLHC

abstract:
  I look for a dijet resonance produced by an excited quark q* in a simulated
sample corresponding to 3 ab^{-1} of pp collisions at $\sqrt{s} = 100$ TeV.
Using a cut and count analysis approach I demonstrate the potential to explore
q* masses up to 50 TeV, corresponding to a length scale of around 4 am.


title: Notes on Leibniz thought experiment

abstract:
  Leibniz thought experiment of perception, sensing, and thinking is
reconsidered. We try to understand Leibniz picture in view of our knowledge of
basic neuroscience. In particular we can see how the emergence of consciousness
could in principle be understood.


title: On Weak Limits and Unimodular Measures

abstract:
  In this thesis, the main objects of study are probability measures on the
isomorphism classes of countable, connected rooted graphs. An important class
of such measures is formed by unimodular measures, which satisfy a certain
equation, sometimes referred to as the intrinsic mass transport principle. The
so-called law of a finite graph is an example of a unimodular measure. We say
that a measure is sustained by a countable graph if the set of rooted connected
components of the graph has full measure. We demonstrate several new results
involving sustained unimodular measures, and provide thorough arguments for
known ones. In particular, we give a criterion for unimodularity on connected
graphs, deduce that connected graphs sustain at most one unimodular measure,
and prove that unimodular measures sustained by disconnected graphs are convex
combinations. Furthermore, we discuss weak limits of laws of finite graphs, and
construct counterexamples to seemingly reasonable conjectures.


title:
An expression of excess work during transition between nonequilibrium
  steady states

abstract:
  Excess work is a non-diverging part of the work during transition between
nonequilibrium steady states (NESSs). It is a central quantity in the steady
state thermodynamics (SST), which is a candidate for nonequilibrium
thermodynamics theory. We derive an expression of excess work during
quasistatic transitions between NESSs by using the macroscopic linear response
relation of NESS. This expression is a line integral of a vector potential in
the space of control parameters. We show a relationship between the vector
potential and the response function of NESS, and thus obtain a relationship
between the SST and a macroscopic quantity. We also connect the macroscopic
formulation to microscopic physics through a microscopic expression of the
nonequilibrium response function, which gives a result consistent with the
previous studies.


title: Anti-Anthropic Solutions to the Cosmic Coincidence Problem

abstract:
  A cosmological constant fits all current dark energy data, but requires two
extreme fine tunings, both of which are currently explained by anthropic
arguments. Here we discuss anti-anthropic solutions to one of these problems:
the cosmic coincidence problem- that today the dark energy density is nearly
equal to the matter density. We replace the ensemble of Universes used in the
anthropic solution with an ensemble of tracking scalar fields that do not
require fine-tuning. This not only does away with the coincidence problem, but
also allows for a Universe that has a very different future than the one
currently predicted by a cosmological constant. These models also allow for
transient periods of significant scalar field energy (SSFE) over the history of
the Universe that can give very different observational signatures as compared
with a cosmological constant, and so can be confirmed or disproved in current
and upcoming experiments.


title: Study of the a_0(980) on the lattice

abstract:
  We present lattice results for the a_0(980) state using a variational
approach with a variety of creation operators: quark-antiquark, mesonic
molecule, diquark-antidiquark as well as two-meson type. Focus is put on recent
technical advances, in particular the computation of singly disconnected
diagrams.


title: Pure state thermodynamics with matrix product states

abstract:
  We extend the formalism of pure state thermodynamics to matrix product
states. In pure state thermodynamics finite temperature properties of quantum
systems are derived without the need of statistical mechanics ensembles, but
instead using typical properties of random pure states. We show that this
formalism can be useful from the computational point of view when combined with
tensor network algorithms. In particular, a recently introduced Monte Carlo
algorithm is considered which samples matrix product states at random for the
estimation of finite temperature observables. Here we characterize this
algorithm as an $(\epsilon, \delta)$-approximation scheme and we analytically
show that sampling one single state is sufficient to obtain a very good
estimation of finite temperature expectation values. These results provide a
substantial computational improvement with respect to similar algorithms for
one-dimensional quantum systems based on uniformly distributed pure states. The
analytical calculations are numerically supported simulating finite temperature
interacting spin systems of size up to 100 qubits.

categories: quant-ph cond-mat.dis-nn cond-mat.stat-mech cond-mat.str-el


title: Just in Time to Flip Your Classroom

abstract:
  With advocates like Sal Khan and Bill Gates, flipped classrooms are
attracting an increasing amount of media and research attention. We had heard
Khan's TED talk and were aware of the concept of inverted pedagogies in
general. Yet, it really hit home when we accidentally flipped our classroom.
Our objective was to better prepare our students for class. We set out to
effectively move some of our course content outside of class and decided to
tweak the Just-in-Time-Teaching approach (JiTT). To our surprise, this tweak -
which we like to call the flip-JiTT - ended up completely flipping our
classroom. What follows is narrative of our experience and a procedure that any
teacher can use to extend JiTT to a flipped classroom.


title: Evolutionary consequences of assortativeness in haploid genotypes

abstract:
  We study the evolution of allele frequencies in a large population where
random mating is violated in a particular way that is related to recent works
on speciation. Specifically, we consider non-random encounters in haploid
organisms described by biallelic genes at two loci and assume that individuals
whose alleles differ at both loci are incompatible. We show that evolution
under these conditions leads to the disappearance of one of the alleles and
substantially reduces the diversity of the population. The allele that
disappears, and the other allele frequencies at equilibrium, depend only on
their initial values, and so does the time to equilibration. However, certain
combinations of allele frequencies remain constant during the process,
revealing the emergence of strong correlation between the two loci promoted by
the epistatic mechanism of incompatibility. We determine the geometrical
structure of the haplotype frequency space and solve the dynamical equations,
obtaining a simple rule to determine equilibrium solution from the initial
conditions. We show that our results are equivalent to selection against double
heterozigotes for a population of diploid individuals and discuss the relevance
of our findings to speciation.


title:
Extended envelopes around Galactic Cepheids IV. T Monocerotis and X
  Sagittarii from mid-infrared interferometry with VLTI/MIDI

abstract:
  Aims. We study the close environment of nearby Cepheids using high spatial
resolution observations in the mid-infrared with the VLTI/MIDI instrument, a
two-beam interferometric recombiner. Methods. We obtained spectra and
visibilities for the classical Cepheids X Sgr and T Mon. We fitted the MIDI
measurements, supplemented by B, V, J, H, K literature photometry, with the
numerical transfer code DUSTY to determine the dust shell parameters. We used a
typical dust composition for circumstellar environments. Results. We detect an
extended dusty environment in the spectra and visibilities for both stars,
although T Mon might suffer from thermal background contamination. We attribute
this to the presence of a circumstellar envelope (CSE) surrounding the
Cepheids. This is optically thin for X Sgr (tau(0.55microns) = 0.008), while it
appears to be thicker for T Mon (tau(0.55micron) = 0.15). They are located at
about 15-20 stellar radii. Following our previous work, we derived a likely
period-excess relation in the VISIR PAH1 filter, f(8.6micron)[%]=
0.81(+/-0.04)P[day]. We argue that the impact of CSEs on the mid-IR
period-luminosity (P-L) relation cannot be negligible because they can bias the
Cepheid brightness by up to about 30 %. For the K-band P-L relation, the CSE
contribution seems to be lower (< 5 %), but the sample needs to be enlarged to
firmly conclude that the impact of the CSEs is negligible in this band.


title: Auxiliary fields in open gauge theories

abstract:
  We show that for open gauge theories, it is possible to build an off-shell
Becchi-Rouet-Stora-Tyutin (BRST) algebra together with an invariant extension
of the classical action. This is based on the introduction of auxiliary fields,
after having defined an on-shell invariant quantum action, where the
gauge-fixing action is written as in Yang-Mills type theories up to a modified
BRST operator. An application to simple supergravity is performed.


title:
Aligned grains and inferred toroidal magnetic fields in the envelopes of
  massive young stellar objects

abstract:
  Massive young stellar objects (YSOs), like low-mass YSOs, are thought to be
surrounded by optically thick envelopes and/or discs and are observed to have
associated regions that produce polarized light at near-infrared wavelengths.
These polarized regions are thought to be lower-density outflows along the
polar axes of the YSO envelopes. Using the 0.2 arcsec spatial resolution of the
Near-Infrared Camera and Multi-Object Spectrometer on the Hubble Space
Telescope we are examining the structure of the envelopes and outflow regions
of massive YSOs in star-forming regions within a few kpc of the Sun. Here we
report on 2 micron polarimetry of Mon R2-IRS3, S140-IRS1, and AFGL 2591.
  All three sources contain YSOs with highly-polarized monopolar outflows, with
Mon R2-IRS3 containing at least two YSOs in a small cluster. The central stars
of all four YSOs are also polarized, with position angles perpendicular to the
directions of the outflows. We infer that this polarization is due to
scattering and absorption by aligned grains. We have modelled our observations
of S140-IRS1 and AFGL 2591 as light scattered and absorbed both by spherical
grains and by elongated grains that are aligned by magnetic fields. Models that
best reproduce the observations have a substantial toroidal component to the
magnetic field in the equatorial plane. Moreover, the toroidal magnetic field
in the model that best fits AFGL 2591 extends a large fraction of the height of
the model cavity, which is 10^5 au. We conclude that the massive YSOs in this
study all show evidence of the presence of a substantial toroidal magnetic
field.


title:
Decay of correlations in 1D lattice systems of continuous spins and
  long-range interaction

abstract:
  We consider an one-dimensional lattice system of unbounded and continuous
spins. The Hamiltonian consists of a perturbed strictly-convex single-site
potential and with longe-range interaction. We show that if the interactions
decay algebraically of order 2+a, a>0 then the correlations also decay
algebraically of order 2+\~a for some \~a > 0. For the argument we generalize a
method from Zegarlinski from finite-range to infinite-range interaction to get
a preliminary decay of correlations, which is improved to the correct order by
a recursive scheme based on Lebowitz inequalities. Because the decay of
correlations yields the uniqueness of the Gibbs measure, the main result of
this article yields that the on-phase region of a continuous spin system is at
least as large as for the Ising model.


title:
Joint Sparse Recovery Method for Compressed Sensing with Structured
  Dictionary Mismatches

abstract:
  In traditional compressed sensing theory, the dictionary matrix is given a
priori, whereas in real applications this matrix suffers from random noise and
fluctuations. In this paper we consider a signal model where each column in the
dictionary matrix is affected by a structured noise. This formulation is common
in direction-of-arrival (DOA) estimation of off-grid targets, encountered in
both radar systems and array processing. We propose to use joint sparse signal
recovery to solve the compressed sensing problem with structured dictionary
mismatches and also give an analytical performance bound on this joint sparse
recovery. We show that, under mild conditions, the reconstruction error of the
original sparse signal is bounded by both the sparsity and the noise level in
the measurement model. Moreover, we implement fast first-order algorithms to
speed up the computing process. Numerical examples demonstrate the good
performance of the proposed algorithm, and also show that the joint-sparse
recovery method yields a better reconstruction result than existing methods. By
implementing the joint sparse recovery method, the accuracy and efficiency of
DOA estimation are improved in both passive and active sensing cases.


title: Torus actions and tensor products of intersection cohomology

abstract:
  Given certain intersection cohomology sheaves on a projective variety with a
torus action, we relate the cohomology groups of their tensor product to the
cohomology groups of the individual sheaves. We also prove a similar result in
the case of equivariant cohomology.


title:
Multi-wavelength Radio Continuum Emission Studies of Dust-free Red
  Giants

abstract:
  Multi-wavelength centimeter continuum observations of non-dusty,
non-pulsating K spectral-type red giants directly sample their chromospheres
and wind acceleration zones. Such stars are feeble emitters at these
wavelengths however, and previous observations have provided only a small
number of modest S/N measurements slowly accumulated over three decades. We
present multi-wavelength Karl G. Jansky Very Large Array thermal continuum
observations of the wind acceleration zones of two dust-free red giants,
Arcturus (Alpha Boo: K2 III) and Aldebaran (Alpha Tau: K5 III). Importantly,
most of our observations of each star were carried out over just a few days, so
that we obtained a snapshot of the different stellar atmospheric layers sampled
at different wavelengths, independent of any long-term variability. We report
the first detections at several wavelengths for each star including a detection
at 10 cm (3.0 GHz: S band) for both stars and a 20 cm (1.5 GHz: L band)
detection for Alpha Boo. This is the first time single luminosity class III red
giants have been detected at these continuum wavelengths. Our long-wavelength
data sample the outer layers of Alpha Boo's atmosphere where its wind velocity
is approaching its terminal value and the ionization balance is becoming
frozen-in. For Alpha Tau, however, our long-wavelength data are still sampling
its inner atmosphere, where the wind is still accelerating probably due to its
lower mass-loss rate. We compare our data with published semi-empirical models
based on ultraviolet data, and the marked deviations highlight the need for new
atmospheric models to be developed. Spectral indices are used to discuss the
possible properties of the stellar atmospheres, and we find evidence for a
rapidly cooling wind in the case of Alpha Boo. Finally, we develop a simple
analytical wind model for Alpha Boo based on our new long-wavelength flux
measurements.


title:
System Power Minimization to Access Non-Contiguous Spectrum in Cognitive
  Radio Networks

abstract:
  Wireless transmission using non-contiguous chunks of spectrum is becoming
increasingly important due to a variety of scenarios such as: secondary users
avoiding incumbent users in TV white space; anticipated spectrum sharing
between commercial and military systems; and spectrum sharing among
uncoordinated interferers in unlicensed bands. Multi-Channel Multi-Radio (MCMR)
platforms and Non-Contiguous Orthogonal Frequency Division Multiple Access
(NC-OFDMA) technology are the two commercially viable transmission choices to
access these non-contiguous spectrum chunks. Fixed MC-MRs do not scale with
increasing number of non-contiguous spectrum chunks due to their fixed set of
supporting radio front ends. NC-OFDMA allows nodes to access these
non-contiguous spectrum chunks and put null sub-carriers in the remaining
chunks. However, nulling sub-carriers increases the sampling rate (spectrum
span) which, in turn, increases the power consumption of radio front ends. Our
work characterizes this trade-off from a cross-layer perspective, specifically
by showing how the slope of ADC/DAC power consumption versus sampling rate
curve influences scheduling decisions in a multi-hop network. Specifically, we
provide a branch and bound algorithm based mixed integer linear programming
solution that performs joint power control, spectrum span selection, scheduling
and routing in order to minimize the system power of multi-hop NC-OFDMA
networks. We also provide a low complexity (O(E^2 M^2)) greedy algorithm where
M and E denote the number of channels and links respectively. Numerical
simulations suggest that our approach reduces system power by 30% over
classical transmit power minimization based cross-layer algorithms.


title: The approach of Otto-Reznikoff revisited

abstract:
  In this article we consider a lattice system of unbounded continuos spins.
Otto & Reznikoff used the two-scale approach to show that exponential decay of
correlations yields a logarithmic Sobolev inequality (LSI) with uniform
constant in the system size. We improve their statement by weakening the
assumptions. For the proof a more detailed analysis based on two new
ingredients is needed. The two new ingredients are a new basic covariance
estimate and a uniform moment estimate. We additionally provide a comparison
principle for covariances showing that the correlations for the conditioned
Gibbs measures are controlled by the correlations of the original Gibbs measure
with ferromagnetic interaction. The latter simplifies the application of the
main result. As an application, we show how decay of correlations combined with
the uniform LSI yields the uniqueness of the infinite-volume Gibbs measure,
generalizing a result of Yoshida form finite-range to infinite-range
interaction.


title:
Harnack Inequalities for Critical 4-manifolds with a Ricci Curvature
  Bound

abstract:
  We study critical Riemannian 4-manifolds with a lower bound on Ricci
curvature, but no a priori analytic constraints such as on Sobolev constants.
We derive elliptic-type estimates for the local curvature radius, which itself
controls sectional curvature. The primary method is construction of blow-ups of
degenerating metrics, followed by a geometric/topological triviality result
from a previous work.


title:
The Hartree approximation in curved spacetimes revisited I: the
  effective potential in de Sitter

abstract:
  We consider a quantum scalar field with {\lambda}{\phi}^4 interaction in
curved spacetimes. The quantum effects are taken into account nonperturbatively
using the Hartree approximation to the 2PI effective action. Although this
approximation has been considered in many previous works, we reconsider it
using a consistent nonperturbative renormalization procedure, which we extend
to general curved spacetimes. We obtain the renormalized equations for the mean
field and for the propagator of the fluctuations, showing explicitly their
independence on the arbitrary scale introduced by the regularization scheme. We
apply our results to the particular case of de Sitter spacetime and discuss
spontaneous symmetry breaking. The results depend strongly on the
renormalization procedure.


title: Soergel Calculus

abstract:
  The monoidal category of Soergel bimodules is an incarnation of the Hecke
category, a fundamental object in representation theory. We present this
category by generators and relations, using the language of planar
diagrammatics. We show that Libedinsky's light leaves give a basis for morphism
spaces and give a new proof of Soergel's classification of the indecomposable
Soergel bimodules.


title: On the Robustness of Temporal Properties for Stochastic Models

abstract:
  Stochastic models such as Continuous-Time Markov Chains (CTMC) and Stochastic
Hybrid Automata (SHA) are powerful formalisms to model and to reason about the
dynamics of biological systems, due to their ability to capture the
stochasticity inherent in biological processes. A classical question in formal
modelling with clear relevance to biological modelling is the model checking
problem. i.e. calculate the probability that a behaviour, expressed for
instance in terms of a certain temporal logic formula, may occur in a given
stochastic process. However, one may not only be interested in the notion of
satisfiability, but also in the capacity of a system to mantain a particular
emergent behaviour unaffected by the perturbations, caused e.g. from extrinsic
noise, or by possible small changes in the model parameters. To address this
issue, researchers from the verification community have recently proposed
several notions of robustness for temporal logic providing suitable definitions
of distance between a trajectory of a (deterministic) dynamical system and the
boundaries of the set of trajectories satisfying the property of interest. The
contributions of this paper are twofold. First, we extend the notion of
robustness to stochastic systems, showing that this naturally leads to a
distribution of robustness scores. By discussing two examples, we show how to
approximate the distribution of the robustness score and its key indicators:
the average robustness and the conditional average robustness. Secondly, we
show how to combine these indicators with the satisfaction probability to
address the system design problem, where the goal is to optimize some control
parameters of a stochastic model in order to best maximize robustness of the
desired specifications.


title: Robustness Analysis for Value-Freezing Signal Temporal Logic

abstract:
  In our previous work we have introduced the logic STL*, an extension of
Signal Temporal Logic (STL) that allows value freezing. In this paper, we
define robustness measures for STL* by adapting the robustness measures
previously introduced for Metric Temporal Logic (MTL). Furthermore, we present
an algorithm for STL* robustness computation, which is implemented in the tool
Parasim. Application of STL* robustness analysis is demonstrated on case
studies.


title: The impact of high density receptor clusters on VEGF signaling

abstract:
  Vascular endothelial growth factor (VEGF) signaling is involved in the
process of blood vessel development and maintenance. Signaling is initiated by
binding of the bivalent VEGF ligand to the membrane-bound receptors (VEGFR),
which in turn stimulates receptor dimerization. Herein, we discuss experimental
evidence that VEGF receptors localize in caveloae and other regions of the
plasma membrane, and for other receptors, it has been shown that receptor
clustering has an impact on dimerization and thus also on signaling. Overall,
receptor clustering is part of a complex ecosystem of interactions and how
receptor clustering impacts dimerization is not well understood. To address
these questions, we have formulated the simplest possible model. We have
postulated the existence of a single high affinity region in the cell membrane,
which acts as a transient trap for receptors. We have defined an ODE model by
introducing high- and low-density receptor variables and introduce the
corresponding reactions from a realistic model of VEGF signal initiation.
Finally, we use the model to investigate the relation between the degree of
VEGFR concentration, ligand availability, and signaling. In conclusion, our
simulation results provide a deeper understanding of the role of receptor
clustering in cell signaling.


title: Falsifying Oscillation Properties of Parametric Biological Models

abstract:
  We propose an approach to falsification of oscillation properties of
parametric biological models, based on the recently developed techniques for
testing continuous and hybrid systems. In this approach, an oscillation
property can be specified using a hybrid automaton, which is then used to guide
the exploration in the state and input spaces to search for the behaviors that
do not satisfy the property. We illustrate the approach with the Laub-Loomis
model for spontaneous oscillations during the aggregation stage of
Dictyostelium.


title: A hybrid mammalian cell cycle model

abstract:
  Hybrid modeling provides an effective solution to cope with multiple time
scales dynamics in systems biology. Among the applications of this method, one
of the most important is the cell cycle regulation. The machinery of the cell
cycle, leading to cell division and proliferation, combines slow growth,
spatio-temporal re-organisation of the cell, and rapid changes of regulatory
proteins concentrations induced by post-translational modifications. The
advancement through the cell cycle comprises a well defined sequence of stages,
separated by checkpoint transitions. The combination of continuous and discrete
changes justifies hybrid modelling approaches to cell cycle dynamics. We
present a piecewise-smooth version of a mammalian cell cycle model, obtained by
hybridization from a smooth biochemical model. The approximate hybridization
scheme, leading to simplified reaction rates and binary event location
functions, is based on learning from a training set of trajectories of the
smooth model. We discuss several learning strategies for the parameters of the
hybrid model.


title: Exploring the Dynamics of Mass Action Systems

abstract:
  We present the Populus toolkit for exploring the dynamics of mass action
systems under different assumptions.


title: Producing a Set of Models for the Iron Homeostasis Network

abstract:
  This paper presents a method for modeling biological systems which combines
formal techniques on intervals, numerical simulations and satisfaction of
Signal Temporal Logic (STL) formulas. The main modeling challenge addressed by
this approach is the large uncertainty in the values of the parameters due to
the experimental difficulties of getting accurate biological data. This method
considers intervals for each parameter and a formal description of the expected
behavior of the model. In a first step, it produces reduced intervals of
possible parameter values. Then by performing a systematic search in these
intervals, it defines sets of parameter values used in the next step. This
procedure aims at finding a sub-space where the model robustly behaves as
expected. We apply this method to the modeling of the cellular iron homeostasis
network in erythroid progenitors. The produced model describes explicitly the
regulation mechanism which acts at the translational level.


title: A Hybrid Model of a Genetic Regulatory Network in Mammalian Sclera

abstract:
  Myopia in human and animals is caused by the axial elongation of the eye and
is closely linked to the thinning of the sclera which supports the eye tissue.
This thinning has been correlated with the overproduction of matrix
metalloproteinase (MMP-2), an enzyme that degrades the collagen structure of
the sclera. In this short paper, we propose a descriptive model of a regulatory
network with hysteresis, which seems necessary for creating oscillatory
behavior in the hybrid model between MMP-2, MT1-MMP and TIMP-2. Numerical
results provide insight on the type of equilibria present in the system.


title: Shortest Paths in Microseconds

abstract:
  Computing shortest paths is a fundamental primitive for several social
network applications including socially-sensitive ranking, location-aware
search, social auctions and social network privacy. Since these applications
compute paths in response to a user query, the goal is to minimize latency
while maintaining feasible memory requirements. We present ASAP, a system that
achieves this goal by exploiting the structure of social networks.
  ASAP preprocesses a given network to compute and store a partial shortest
path tree (PSPT) for each node. The PSPTs have the property that for any two
nodes, each edge along the shortest path is with high probability contained in
the PSPT of at least one of the nodes. We show that the structure of social
networks enable the PSPT of each node to be an extremely small fraction of the
entire network; hence, PSPTs can be stored efficiently and each shortest path
can be computed extremely quickly.
  For a real network with 5 million nodes and 69 million edges, ASAP computes a
shortest path for most node pairs in less than 49 microseconds per pair. ASAP,
unlike any previous technique, also computes hundreds of paths (along with
corresponding distances) between any node pair in less than 100 microseconds.
Finally, ASAP admits efficient implementation on distributed programming
frameworks like MapReduce.


title:
Measurements of Cyclotron Features and Pulse Periods in the High-Mass
  X-Ray Binaries 4U 1538-522 and 4U 1907+09 with INTEGRAL

abstract:
  We present a spectral and timing analysis of INTEGRAL observations of two
high mass X-ray binaries, 4U 1538-522 and 4U 1907+09. Our timing measurements
for 4U 1538-522 find the pulse period to have exhibited a spin-up trend until
approximately 2009, after which there is evidence for a torque reversal, with
the source beginning to spin down to the most recently-measured period of
525.407 +/- 0.001 s. The most recent INTEGRAL observations of 4U 1907+09 are
not found to yield statistically significant pulse periods due to the
significantly lower flux from the source compared to 4U 1538-522. A spectral
model consisting of a power-law continuum with an exponential cutoff and
modified by two cyclotron resonance scattering features is found to fit both
sources well, with the cyclotron scattering features detected at ~22 and ~49
keV for 4U 1538-522 and at ~18 and ~36 keV in 4U 1907+09. The spectral
parameters of 4U 1538-522 are generally not found to vary significantly with
flux, and there is little to no variation across the torque reversal. Examining
our results in conjunction with previous work, we find no evidence for a
correlation between cyclotron line energy and luminosity for 4U 1538-522. 4U
1907+09 shows evidence for a positive correlation between cyclotron line energy
and luminosity, which would make it the fourth, and lowest-luminosity,
cyclotron line source to exhibit this relationship


title: Hamiltonian Learning and Certification Using Quantum Resources

abstract:
  In recent years quantum simulation has made great strides culminating in
experiments that operate in a regime that existing supercomputers cannot easily
simulate. Although this raises the possibility that special purpose analog
quantum simulators may be able to perform computational tasks that existing
computers cannot, it also introduces a major challenge: certifying that the
quantum simulator is in fact simulating the correct quantum dynamics. We
provide an algorithm that, under relatively weak assumptions, can be used to
efficiently infer the Hamiltonian of a large but untrusted quantum simulator
using a trusted quantum simulator. We illustrate the power of this approach by
showing numerically that it can inexpensively learn the Hamiltonians for large
frustrated Ising models, demonstrating that quantum resources can make
certifying analog quantum simulators tractable.


title: Analytic Function Theory for Operator-Valued Free Probability

abstract:
  It is a classical result in complex analysis that the class of functions that
arise as the Cauchy transform of probability measures may be characterized
entirely in terms of their analytic and asymptotic properties. Such transforms
are a main object of study in non-commutative probability theory as the
function theory encodes information on the probability measures and the various
convolution operations. In extending this theory to operator-valued free
probability theory, the analogue of the Cauchy transform is a non-commutative
function with domain equal to the non-commutative upper-half plane. In this
paper, we prove an analogous characterization of the Cauchy transforms, again,
entirely in terms of their analytic and asymptotic behavior. We further
characterize those functions which arise as the Voiculescu transform of
$\boxplus$-infinitely divisible $\mathcal{B}$-valued distributions. As
consequences of these results, we provide a characterization of infinite
divisibility in terms of the domain of the relevant Voiculescu transform,
provide a purely analytic definition of the semigroups of completely positive
maps associated to infinitely divisible distributions and provide a Nevanlinna
representation for non-commutative functions with the appropriate asymptotic
behavior.


title: Time Reversal Invariant Topologically Insulating Circuits

abstract:
  From studies of exotic quantum many-body phenomena to applications in
spintronics and quantum information processing, topological materials are
poised to revolutionize the condensed matter frontier and the landscape of
modern materials science. Accordingly, there is a broad effort to realize
topologically non-trivial electronic and photonic materials for fundamental
science as well as practical applications. In this work, we demonstrate the
first simultaneous site- and time- resolved measurements of a time reversal
invariant topological band-structure, which we realize in a radio frequency
(RF) photonic circuit. We control band-structure topology via local permutation
of a traveling wave capacitor-inductor network, increasing robustness by going
beyond the tight-binding limit. We observe a gapped density of states
consistent with a modified Hofstadter spectrum at a flux per plaquette of
$\phi=\pi/2$. In-situ probes of the band-gaps reveal spatially-localized
bulk-states and de-localized edge-states. Time-resolved measurements reveal
dynamical separation of localized edge-excitations into spin-polarized
currents. The RF circuit paradigm is naturally compatible with non-local
coupling schemes, allowing us to implement a M\"{o}bius strip topology
inaccessible in conventional systems. This room-temperature experiment
illuminates the origins of topology in band-structure, and when combined with
circuit quantum electrodynamics (QED) techniques, provides a direct path to
topologically-ordered quantum matter.


title: Charge Symmetry Breaking and Parity Violating Electron Scattering

abstract:
  I review the effects of charge symmetry breaking CSB on electromagnetic form
factors and how that influences extraction of information regarding nucleon
strangeness content and the weak mixing angle. It seems that CSB effects are
very modest and should not impact the analysis of experiments.


title: Asymptotic behavior of the dimension of the Chow variety

abstract:
  We analyze the asymptotics of the dimension of components of the Chow variety
as degree increases. By analogy with the divisor case, the main goal is to
relate the asymptotic behavior with the positivity of the corresponding cycle
classes. We also compute the dimension of the Chow variety of projective space.


title: Surface Waves in the paritally ionized solar plasma slab

abstract:
  The properties of surface waves in the partially ionized, incompressible
magnetized plasma slab are investigated in the present work. The waves are
affected by the non ideal MHD effects which causes the finite drift of the
magnetic field in the medium. When the finite drift of the magnetic field is
ignored, the characteristics of the wave propagation in the partially ionized
plasma fluid is similar to the ideal MHD except now the propagation properties
depend on the fractional ionization of the medium. In the presence of Hall
diffusion, the propagation of the sausage and kink surface waves depends on the
level of fractional ionization of the medium. When both the Hall and Pedersen
diffusion are present in the medium, the waves undergoes damping. For typical
solar parameters, waves may damp over few minutes.


title:
Optical linear polarization measurements of WR massive binary and single
  stars

abstract:
  We present optical (UBVRI) linear polarimetric observations of 8 Wolf-Rayet
(WR) massive binaries and single stars. We have corrected the observed values
for the interstellar extinction and polarization by the interstellar medium to
obtain the intrinsic polarization and position angle. We find three highly
polarization stars between 5% and 10% (WR1, WR5 and WR146), three between 3%
and 4% (WR2, WR3 and WR4), and two between 1% and 2% (WR137 and WR140).
Moreover, 5 stars show increasing degree of polarization to shorter wavelengths
(e.g WR 146) indicative with asymmetric circumstellar envelope and 3 have
nearly constant polarization within the errors (e.g WR 140).


title:
Fermi surface renormalization and quantum confinement in the two-coupled
  chains model

abstract:
  We address the problem of the Fermi surface renormalization and the quantum
confinement regime (QCR) in the two coupled chains model(TCCM) of spinless
fermions. We perform a self-consistent calculation of the renormalization
group(RG) flows of the renormalized TCCM couplings and quasiparticle weight. On
top of that we take explicitly into account the renormalization of the Fermi
surface. The flow of the difference of the renormalized Fermi wave vectors
associated with the bonding and antibonding bands has a dramatic effect on the
single particle spectrum. Although the quasiparticle amplitude is nullified
already at intermediate coupling the QCR is only observed at strong coupling.
The state associated with this regime has a charge gap and it is not a
Luttinger liquid. In contrast, the Fermi liquid regime is stabilized by the
umklapp "$g_2$--like" interactions at very weak coupling regime.


abstract:
  In this paper, we consider Poisson-Charlier and poly-Cauchy mixed type
polynomials and give various identities of those polynomials which are derived
from umbral calculus.


title: Scattering of Massless Particles: Scalars, Gluons and Gravitons

abstract:
  In a recent note we presented a compact formula for the complete tree-level
S-matrix of pure Yang-Mills and gravity theories in arbitrary spacetime
dimension. In this paper we show that a natural formulation also exists for a
massless colored cubic scalar theory. In Yang-Mills, the formula is an integral
over the space of n marked points on a sphere and has as integrand two factors.
The first factor is a combination of Parke-Taylor-like terms dressed with U(N)
color structures while the second is a Pfaffian. The S-matrix of a U(N)xU(N')
cubic scalar theory is obtained by simply replacing the Pfaffian with a U(N')
version of the previous U(N) factor. Given that gravity amplitudes are obtained
by replacing the U(N) factor in Yang-Mills by a second Pfaffian, we are led to
a natural color-kinematics correspondence. An expansion of the integrand of the
scalar theory leads to sums over trivalent graphs and are directly related to
the KLT matrix. We find a connection to the BCJ color-kinematics duality as
well as a new proof of the BCJ doubling property that gives rise to gravity
amplitudes. We end by considering a special kinematic point where the partial
amplitude simply counts the number of color-ordered planar trivalent trees,
which equals a Catalan number. The scattering equations simplify dramatically
and are equivalent to a special Y-system with solutions related to roots of
Chebyshev polynomials.


title: Spectroscopic analysis of DA white dwarfs with 3D model atmospheres

abstract:
  We present the first grid of mean three-dimensional (3D) spectra for
pure-hydrogen (DA) white dwarfs based on 3D model atmospheres. We use CO5BOLD
radiation-hydrodynamics 3D simulations instead of the mixing-length theory for
the treatment of convection. The simulations cover the effective temperature
range of 6000 < Teff (K) < 15,000 and the surface gravity range of 7 < log g <
9 where the large majority of DAs with a convective atmosphere are located. We
rely on horizontally averaged 3D structures (over constant Rosseland optical
depth) to compute <3D> spectra. It is demonstrated that our <3D> spectra can be
smoothly connected to their 1D counterparts at higher and lower Teff where the
3D effects are small. Analytical functions are provided in order to convert
spectroscopically determined 1D effective temperatures and surface gravities to
3D atmospheric parameters. We apply our improved models to well studied
spectroscopic data sets from the Sloan Digital Sky Survey and the White Dwarf
Catalog. We confirm that the so-called high-log g problem is not present when
employing <3D> spectra and that the issue was caused by inaccuracies in the 1D
mixing-length approach. The white dwarfs with a radiative and a convective
atmosphere have derived mean masses that are the same within ~0.01 Msun, in
much better agreement with our understanding of stellar evolution. Furthermore,
the 3D atmospheric parameters are in better agreement with independent Teff and
log g values from photometric and parallax measurements.


title: Strong Gravitational Lensing and Its Cosmic Constraints

abstract:
  In this paper, we propose a new method to use the strong lensing data sets to
constrain a cosmological model. By taking the ratio
$\mathcal{D}^{obs}_{ij}=\theta_{\mathrm{E_{\mathrm{i}}}}\sigma_{\mathrm{0_{\mathrm{j}}}}^2/\theta_{\mathrm{E_{\mathrm{j}}}}\sigma_{\mathrm{0_{\mathrm{i}}}}^2$
as cosmic observations, one can {\it completely} eliminate the uncertainty
caused by the relation $\sigma_{\mathrm{SIS}}=f_{\mathrm{E}}\sigma_0$ which
characterizes the relation between the stellar velocity dispersion $\sigma_0$
and the velocity dispersion $\sigma_{SIS}$. Via our method, a relative tight
constraint to the cosmological model space can be obtained, for the spatially
flat $\Lambda$CDM model as an example $\Omega_m=0.143_{- 0.143-0.143-0.143}^{+
0.000769+0.143+0.489}$ in $3\sigma$ regions. And by using this method, one can
also probe the nature of dark energy and the spatial curvature of our Universe.


title: Chromatic-choosability of the power of graphs

abstract:
  The $k$th power $G^k$ of a graph $G$ is the graph defined on $V(G)$ such that
two vertices $u$ and $v$ are adjacent in $G^k$ if the distance between $u$ and
$v$ in $G$ is at most $k$. Let $\chi(H)$ and $\chi_l(H)$ be the chromatic
number and the list chromatic number of $H$, respectively. A graph $H$ is
called {\em chromatic-choosable} if $\chi_l (H) = \chi(H)$. It is an
interesting problem to find graphs that are chromatic-choosable. A natural
question raised by Xuding Zhu (2012) is whether there exists a constant integer
$k$ such that $G^k$ is chromatic-choosable for every graph $G$. Motivated by
the List Total Coloring Conjecture, Kostochka and Woodall (2001) asked whether
$G^2$ is chromatic-choosable for every graph $G$. Kim and Park (2013) answered
the Kostochka and Woodall's question in the negative by finding a family of
graphs whose squares are complete multipartite graphs with partite sets of
equal and unbounded size. In this paper, we answer Zhu's question by showing
that for every integer $k \geq 2$, there exists a graph $G$ such that $G^k$ is
not chromatic-choosable. Moreover, for any fixed $k$ we show that the value
$\chi_l(G^k) - \chi(G^k)$ can be arbitrarily large.


title:
Edge reconstruction of fractional quantum Hall liquids with spin degrees
  of freedom

abstract:
  We study the interplay of confining potential, electron-electron interaction,
and Zeeman splitting at the edges of fractional quantum Hall liquids, using
numerical diagonalization of finite-size systems. The filling factors studied
include 1/3, 5/2, 2/5, and 2/3. In the absence of Zeeman splitting and an edge,
the first two have spin fully polarized ground states, while the latter two
have singlet ground states. We find that with few exceptions, edge
instabilities of these systems are triggered by softening of edge spin waves
for Abelian fractional quantum Hall liquids (1/3, 2/5 and 2/3 liquids), and are
triggered by softening of edge magnetoplasmon excitations for non-Abelian 5/2
liquid at the smoother confinement side. Phase diagrams are obtained in the
accessible parameter spaces.


title: Non-monotonic Pre-fixed Points and Learning

abstract:
  We consider the problem of finding pre-fixed points of interactive realizers
over arbitrary knowledge spaces, obtaining a relative recursive procedure.
Knowledge spaces and interactive realizers are an abstract setting to represent
learning processes, that can interpret non-constructive proofs. Atomic pieces
of information of a knowledge space are stratified into levels, and evaluated
into truth values depending on knowledge states. Realizers are then used to
define operators that extend a given state by adding and possibly removing
atoms: in a learning process states of knowledge change nonmonotonically.
Existence of a pre-fixed point of a realizer is equivalent to the termination
of the learning process with some state of knowledge which is free of patent
contradictions and such that there is nothing to add. In this paper we
generalize our previous results in the case of level 2 knowledge spaces and
deterministic operators to the case of omega-level knowledge spaces and of
non-deterministic operators.


title: From Branching to Linear Time, Coalgebraically

abstract:
  We consider state-based systems modelled as coalgebras whose type
incorporates branching, and show that by suitably adapting the definition of
coalgebraic bisimulation, one obtains a general and uniform account of the
linear-time behaviour of a state in such a coalgebra. By moving away from a
boolean universe of truth values, our approach can measure the extent to which
a state in a system with branching is able to exhibit a particular linear-time
behaviour. This instantiates to measuring the probability of a specific
behaviour occurring in a probabilistic system, or measuring the minimal cost of
exhibiting a specific behaviour in the case of weighted computations.


title: A Coinductive Approach to Proof Search

abstract:
  We propose to study proof search from a coinductive point of view. In this
paper, we consider intuitionistic logic and a focused system based on
Herbelin's LJT for the implicational fragment. We introduce a variant of lambda
calculus with potentially infinitely deep terms and a means of expressing
alternatives for the description of the "solution spaces" (called B\"ohm
forests), which are a representation of all (not necessarily well-founded but
still locally well-formed) proofs of a given formula (more generally: of a
given sequent).
  As main result we obtain, for each given formula, the reduction of a
coinductive definition of the solution space to a effective coinductive
description in a finitary term calculus with a formal greatest fixed-point
operator. This reduction works in a quite direct manner for the case of Horn
formulas. For the general case, the naive extension would not even be true. We
need to study "co-contraction" of contexts (contraction bottom-up) for dealing
with the varying contexts needed beyond the Horn fragment, and we point out the
appropriate finitary calculus, where fixed-point variables are typed with
sequents. Co-contraction enters the interpretation of the formal greatest fixed
points - curiously in the semantic interpretation of fixed-point variables and
not of the fixed-point operator.


title:
Infinitary Axiomatization of the Equational Theory of Context-Free
  Languages

abstract:
  We give a natural complete infinitary axiomatization of the equational theory
of the context-free languages, answering a question of Lei{\ss} (1992).


title:
The Fixed-Point Theory of Strictly Contracting Functions on Generalized
  Ultrametric Semilattices

abstract:
  We introduce a new class of abstract structures, which we call generalized
ultrametric semilattices, and in which the meet operation of the semilattice
coexists with a generalized distance function in a tightly coordinated way. We
prove a constructive fixed-point theorem for strictly contracting functions on
directed-complete generalized ultrametric semilattices, and introduce a
corresponding induction principle. We cite examples of application in the
semantics of logic programming and timed computation, where, until now, the
only tool available has been the non-constructive fixed-point theorem of
Priess-Crampe and Ribenboim for strictly contracting functions on spherically
complete generalized ultrametric semilattices.


title:
Guard Your Daggers and Traces: On The Equational Properties of Guarded
  (Co-)recursion

abstract:
  Motivated by the recent interest in models of guarded (co-)recursion we study
its equational properties. We formulate axioms for guarded fixpoint operators
generalizing the axioms of iteration theories of Bloom and Esik. Models of
these axioms include both standard (e.g., cpo-based) models of iteration
theories and models of guarded recursion such as complete metric spaces or the
topos of trees studied by Birkedal et al. We show that the standard result on
the satisfaction of all Conway axioms by a unique dagger operation generalizes
to the guarded setting. We also introduce the notion of guarded trace operator
on a category, and we prove that guarded trace and guarded fixpoint operators
are in one-to-one correspondence. Our results are intended as first steps
leading to the description of classifying theories for guarded recursion and
hence completeness results involving our axioms of guarded fixpoint operators
in future work.


title: {\L}ukasiewicz mu-Calculus

abstract:
  The paper explores properties of {\L}ukasiewicz mu-calculus, a version of the
quantitative/probabilistic modal mu-calculus containing both weak and strong
conjunctions and disjunctions from {\L}ukasiewicz (fuzzy) logic. We show that
this logic encodes the well-known probabilistic temporal logic PCTL. And we
give a model-checking algorithm for computing the rational denotational value
of a formula at any state in a finite rational probabilistic nondeterministic
transition system.


title:
Dynamics of Open-Source Software Developer's Commit Behavior: An
  Empirical Investigation of Subversion

abstract:
  Commit is an important operation of revision control for open-source software
(OSS). Recent research has been pursued to explore the statistical laws of such
an operation, but few of those papers conduct empirical investigations on
commit interval (i.e., the waiting time between two consecutive commits). In
this paper, we investigated software developer's collective and individual
commit behavior in terms of the distribution of commit intervals, and found
that 1) the data sets of project-level commit interval within both the
lifecycle and each release of the projects analyzed roughly follow power-law
distributions; and 2) lifecycle- and release-level collective commit interval
on class files can also be best fitted with power laws. These findings reveal
some general (collective) collaborative development patterns of OSS projects,
e.g., most of the waiting times between two consecutive commits to a central
repository are short, but only a few of them experience a long duration of
waiting. Then, the implications of what we found for OSS research were
outlined, which could provide an insight into understanding OSS development
processes better based on software developers' historical commit behavior.


title: Two-Hop Interference Channels: Impact of Linear Schemes

abstract:
  We consider the two-hop interference channel (IC), which consists of two
source-destination pairs communicating with each other via two relays. We
analyze the degrees of freedom (DoF) of this network when the relays are
restricted to perform linear schemes, and the channel gains are constant (i.e.,
slow fading). We show that, somewhat surprisingly, by using vector-linear
strategies at the relays, it is possible to achieve 4/3 sum-DoF when the
channel gains are real. The key achievability idea is to alternate relaying
coefficients across time, to create different end-to-end interference
structures (or topologies) at different times. Although each of these
topologies has only 1 sum-DoF, we manage to achieve 4/3 by coding across them.
Furthermore, we develop a novel outer bound that matches our achievability,
hence characterizing the sum-DoF of two-hop interference channels with linear
schemes. As for the case of complex channel gains, we characterize the sum-DoF
with linear schemes to be 5/3. We also generalize the results to the
multi-antenna setting, characterizing the sum-DoF with linear schemes to be
2M-1/3 (for complex channel gains), where M is the number of antennas at each
node.


title:
Computer simulation of a-Si/c-Si heterojunction solar cell with high
  conversion efficiency

abstract:
  The p-type amorphous/ n-type crystalline silicon (P+ a-Si/N+ c-Si)
heterojunction was simulated for developing the solar cells with high
conversion efficiency and low cost. The characteristic of such cells with
different work function of transparent conductive oxide (TCO) were calculated.
The energy band structure, quantum efficiency and electric field are analyzed
in detail to understand the mechanism of the heterojunction cell. Our results
show that the a-Si/c-Si heterojunction is hypersensitive to the TCO work
function, and the TCO work function should be large enough in order to achieve
high conversion efficiency for P+ a-Si:H/N+ c-Si solar cell. With the optimized
parameters set, the P+ a-Si:H/N+ c-Si solar cell reaches a high efficiency
({\eta}) up to 21.849% (FF: 0.866, VOC: 0.861 V, JSC: 29.32 mA/cm2).


title: Normal form theory for reversible equivariant vector fields

abstract:
  We give an alternative method to obtain normal forms of reversible
equivariant vector fields. We adapt the classical method using tools from
invariant theory to establish formulae that take symmetries into account as a
starting point. Normal forms of two classes of non-resonant and resonant cases
are presented, both under a Z_2-action with linearization having a
2-dimensional nilpotent part and a semisimple part with purely imaginary
eigenvalues.


title: Thermodynamic curvature and black holes

abstract:
  I give a relatively broad survey of thermodynamic curvature $R$, one spanning
results in fluids and solids, spin systems, and black hole thermodynamics. $R$
results from the thermodynamic information metric giving thermodynamic
fluctuations. $R$ has a unique status in thermodynamics as being a geometric
invariant, the same for any given thermodynamic state. In fluid and solid
systems, the sign of $R$ indicates the character of microscopic interactions,
repulsive or attractive. $|R|$ gives the average size of organized mesoscopic
fluctuating structures. The broad generality of thermodynamic principles might
lead one to believe the same for black hole thermodynamics. This paper explores
this issue with a systematic tabulation of results in a number of cases.


title:
Synchronization of Fractional-order Chaotic Systems with Gaussian
  fluctuation by Sliding Mode Control

abstract:
  This paper is devoted to the problem of synchronization between
fractional-order chaotic systems with Gaussian fluctuation by the method of
fractional-order sliding mode control. A fractional integral (FI) sliding
surface is proposed for synchronizing the uncertain fractional-order system,
and then the sliding mode control technique is carried out to realize the
synchronization of the given systems. One theorem about sliding mode controller
is presented to prove the proposed controller can make the system synchronize.
As a case study, the presented method is applied to the fractional-order
Chen-L\"u system as the drive-response dynamical system. Simulation results
show a good performance of the proposed control approach in synchronizing the
chaotic systems in presence of Gaussian noise.


title: Birationally rigid Fano threefold hypersurfaces

abstract:
  We prove that every quasi-smooth hypersurface in the 95 families of weighted
Fano threefold hypersurfaces is birationally rigid.


title:
The Availability of Logical Operation Induced by Dichotomous Noise for a
  Nonlinear Bistable System

abstract:
  Instead of a continuous system driven by Gaussian white noise, logical
stochastic resonance will be investigated in a nonlinear bistable system with
two thresholds driven by dichotomous noise, which shows a phenomenon different
from Gaussian white noise. We can realize two parallel logical operations by
simply adjusting the values of these two thresholds. Besides, to quantify the
reliability of obtaining the correct logic output, we numerically calculate the
success probability, and effects of dichotomous noise on the success
probability are observed, these observations show that the reliability of
realizing logical operation in the bistable system can be improved through
optimizing parameters of dichotomous noise.


title:
SOPHIE velocimetry of Kepler transit candidates IX. KOI-415 b: a
  long-period, eccentric transiting brown dwarf to an evolved Sun

abstract:
  We report the discovery of a long-period brown-dwarf transiting companion of
the solar-type star KOI-415. The transits were detected by the Kepler space
telescope. We conducted Doppler measurements using the SOPHIE spectrograph at
the Observatoire de Haute-Provence. The photometric and spectroscopic signals
allow us to characterize a 62.14+-2.69 Mjup, brown-dwarf companion of an
evolved 0.94+-0.06 Msun star in a highly eccentric orbit of P =
166.78805+-0.00022 days and e = 0.698+-0.002. The radius of KOI-415 b is 0.79
(-0.07,+0.12) Rjup, a value that is compatible with theoretical predictions for
a 10 Gyr, low-metallicity and non-irradiated object.


title: On a Curious Biconditional Involving Divisors of Odd Perfect Numbers

abstract:
  We investigate the implications of a curious biconditional involving divisors
of odd perfect numbers, if Dris conjecture that $q^k < n$ holds, where $q^k
n^2$ is an odd perfect number with Euler prime $q$. We then show that this
biconditional holds unconditionally. Lastly, we prove that the inequality $q<n$
holds unconditionally.


title: On the thermodynamics of universal horizons in Einstein-{\AE}ther theory

abstract:
  The theories of gravity which violate local Lorentz invariance do not admit a
universal maximum speed of signal-propagation. Different field excitations see
a different effective metric and hence a different light cone. In these
theories, although one can define the Killing horizon in a conventional way,
this definition does not capture the notion of a black hole. This is so because
there exist modes which see a wider light cone than the one defined by the
Killing Horizon and therefore can escape to infinity. However, there exist
solutions of these theories which admit a special spacelike hypersurface which
acts as a one-way membrane. Signals from beyond this hypersurface can never
escape to infinity and are destined to hit the singularity. In this sense this
hypersurface acts like a black-hole horizon and is called the Universal Horizon
because it traps modes travelling with arbitrarily high velocities. We use the
Noether charge method {\it \`a la} Wald to show that a first law, which
resembles the first law of thermodynamics, can be formulated for universal
horizons in the Einstein-{\AE}ther theory. This seems to suggest that in
Lorentz violating theories one should ascribe the thermodynamical properties to
the universal horizon and not to the Killing horizon.


title: Asymptotic relations for weighted finite multiple zeta values

abstract:
  Multiple zeta values are real numbers defined by an infinite series
generalizing values of the Riemann zeta function at positive integers. Finite
truncations of this series are called multiple harmonic sums and are known to
have interesting arithmetic properties. When the truncation point is one less
than a prime $p$, the mod $p$ values of multiple harmonic sums are called
finite multiple zeta values. The present work introduces a new class of
congruence for multiple harmonic sums, which we call weighted congruences.
These congruences can hold modulo arbitrarily large powers of $p$. Unlike
results for finite multiple zeta values, weighted congruences typically involve
harmonic sums of multiple weights, which are multiplied by explicit powers of
$p$ depending on weight. We also introduce certain formal weighted congruences
inolving an infinite number of terms, which we call asymptotic relations. We
define a weighted analogue of the finite multiple zeta function, and give an
algebraic framework for classifying weighted congruences and asymptotic
relations.


title: Current-Induced Gap Suppression in the Mott Insulator Ca$_2$RuO$_4$

abstract:
  We present nonlinear conduction phenomena in the Mott insulator Ca2RuO4
investigated with a proper evaluation of self-heating effects. By utilizing a
non-contact infrared thermometer, the sample temperature was accurately
determined even in the presence of large Joule heating. We find that the
resistivity continuously decreases with currents under an isothermal
environment. The nonlinearity and the resulting negative differential
resistance occurs at relatively low current range, incompatible with
conventional mechanisms such as hot electron or impact ionization. We propose a
possible current-induced gap suppression scenario, which is also discussed in
non-equilibrium superconducting state or charge-ordered insulator.


title:
A Search for Astrophysical Burst Signals at the Sudbury Neutrino
  Observatory

abstract:
  The Sudbury Neutrino Observatory (SNO) has confirmed the standard solar model
and neutrino oscillations through the observation of neutrinos from the solar
core. In this paper we present a search for neutrinos associated with sources
other than the solar core, such as gamma-ray bursters and solar flares. We
present a new method for looking for temporal coincidences between neutrino
events and astrophysical bursts of widely varying intensity. No correlations
were found between neutrinos detected in SNO and such astrophysical sources.


title: A Bayesian information criterion for singular models

abstract:
  We consider approximate Bayesian model choice for model selection problems
that involve models whose Fisher-information matrices may fail to be invertible
along other competing submodels. Such singular models do not obey the
regularity conditions underlying the derivation of Schwarz's Bayesian
information criterion (BIC) and the penalty structure in BIC generally does not
reflect the frequentist large-sample behavior of their marginal likelihood.
While large-sample theory for the marginal likelihood of singular models has
been developed recently, the resulting approximations depend on the true
parameter value and lead to a paradox of circular reasoning. Guided by examples
such as determining the number of components of mixture models, the number of
factors in latent factor models or the rank in reduced-rank regression, we
propose a resolution to this paradox and give a practical extension of BIC for
singular model selection problems.


title:
Rigidity theorems for glued spaces being suspensions, cones and joins in
  Alexandrov geometry with curvature bounded below

abstract:
  In the paper, we give rigidity theorems when the glued space of two
Alexandrov spapces with curvature bounded below is a suspension, cone or join.
And we list some basic properties of joins in Appendix.


title: Running couplings with a vanishing scale anomaly

abstract:
  Running couplings can be understood as arising from the spontaneous breaking
of an exact scale invariance in appropriate effective theories with no
dilatation anomaly. Any ordinary quantum field theory, even if it has massive
fields, can be embedded into a theory with spontaneously broken exact scale
invariance in such a way that the ordinary running is recovered in the
appropriate limit, as long as the potential has a flat direction. These
scale-invariant theories, however, do not necessarily solve the cosmological
constant or naturalness problems, which become manifest in the need to
fine-tune dimensionless parameters.


title:
Origin and reduction of wakefields in photonic crystal accelerator
  cavities

abstract:
  Photonic crystal (PhC) defect cavities that support an accelerating mode tend
to trap unwanted higher-order modes (HOMs) corresponding to zero-group-velocity
PhC lattice modes at the top of the bandgap. The effect is explained quite
generally from photonic band and perturbation theoretical arguments. Transverse
wakefields resulting from this effect are observed in a hybrid dielectric PhC
accelerating cavity based on a triangular lattice of sapphire rods. These
wakefields are, on average, an order of magnitude higher than those in the
waveguide-damped Compact Linear Collider (CLIC) copper cavities. The avoidance
of translational symmetry (and, thus, the bandgap concept) can dramatically
improve HOM damping in PhC-based structures.


title: A Torsional Topological Invariant

abstract:
  Curvature and torsion are the two tensors characterizing a general Riemannian
spacetime. In Einstein's general theory of gravitation, with torsion postulated
to vanish and the affine connection identified to the Christoffel symbol, only
the curvature tensor plays the central role. For such a purely metric geometry,
two well-known topological invariants, namely the Euler class and the
Pontryagin class, are useful in characterizing the topological properties of
the spacetime. From a gauge theory point of view, and especially in the
presence of spin, torsion naturally comes into play, and the underlying
spacetime is no longer purely metric. We describe a torsional topological
invariant, discovered in 1982, that has now found increasing usefulness in
recent developments.


title:
The giant lobes of Centaurus A observed at 118 MHz with the Murchison
  Widefield Array

abstract:
  We present new wide-field observations of Centaurus A (Cen A) and the
surrounding region at 118 MHz with the Murchison Widefield Array (MWA) 32-tile
prototype, with which we investigate the spectral-index distribution of Cen A's
giant radio lobes. We compare our images to 1.4 GHz maps of Cen A and compute
spectral indices using temperature-temperature plots and spectral tomography.
We find that the morphologies at 118 MHz and 1.4 GHz match very closely apart
from an extra peak in the southern lobe at 118 MHz, which provides tentative
evidence for the existence of a southern counterpart to the northern middle
lobe of Cen A. Our spatially-averaged spectral indices for both the northern
and southern lobes are consistent with previous analyses, however we find
significant spatial variation of the spectra across the extent of each lobe.
Both the spectral-index distribution and the morphology at low radio
frequencies support a scenario of multiple outbursts of activity from the
central engine. Our results are consistent with inverse-Compton modelling of
radio and gamma-ray data that supports a value for the lobe age of between 10
and 80 Myr.


title: Bending-Induced Delamination of van der Waals Solids

abstract:
  Although sheets of layered van der Waals solids offer great opportunities to
custom-design nanomaterial properties, their weak interlayer adhesion
challenges structural stability against mechanical deformation. Here,
bending-induced delamination of multilayer sheets is investigated by molecular
dynamics simulations, using graphene as an archetypal van der Waals solid.
Simulations show that delamination of a graphene sheet occurs when its radius
of curvature decreases roughly below $R_c=5.3\text{nm}\times (\text{number of
layers})^{3/2}$ and that, as a rule, one-third of the layers get delaminated.
These clear results are explained by a general and transparent model, a useful
future reference for guiding the design of nanostructured van der Waals solids.


title:
New Uses for the Kepler Telescope: A Survey of the Ecliptic Plane For
  Transiting Planets and Star Formation

abstract:
  With the loss of two reaction wheels, the period of Kepler's ultra-high
precision photometric performance is at an end. Yet Kepler retains unique
capabilities impossible to replicate from the ground or with existing or future
space missions. This White Paper calls for the use of Kepler to conduct a
survey in the ecliptic plane to search for planet transits around stars at high
galactic latitudes and to study star forming regions to investigate physics of
very young stars not studied by Kepler in its prime mission. Even with reduced
photometric precision, Kepler's 1 m aperture will enable it to survey faint M
stars to find ice giants and Super Earths in Habitable Zone orbits.


title:
Downsizing of galaxies vs upsizing of dark-halos in a Lambda-CDM
  cosmology

abstract:
  The mass assembly of a whole population of sub-Milky Way galaxies is studied
by means of hydrodynamical simulations within the $\Lambda$-CDM cosmology. Our
results show that while dark halos assemble hierarchically, in stellar mass
this trend is inverted in the sense that the smaller the galaxy, the later is
its stellar mass assembly on average. Our star formation and supernovae
feedback implementation in a multi-phase interstellar medium seems to play a
key role on this process. However, the obtained downsizing trend is not yet as
strong as observations show.


title: Topology of geometric joins

abstract:
  We consider the geometric join of a family of subsets of the Euclidean space.
This is a construction frequently used in the (colorful) Carath\'eodory and
Tverberg theorems, and their relatives. We conjecture that when the family has
at least $d+1$ sets, where $d$ is the dimension of the space, then the
geometric join is contractible. We are able to prove this when $d$ equals $2$
and $3$, while for larger $d$ we show that the geometric join is contractible
provided the number of sets is quadratic in $d$. We also consider a matroid
generalization of geometric joins and provide similar bounds in this case.


title:
The Witten-Reshetikhin-Turaev representation of the Kauffman skein
  algebra

abstract:
  For A a primitive 2N-root of unity with N odd, the Witten-Reshetikhin-Turaev
topological quantum field theory provides a representation of the Kauffman
skein algebra of a closed surface. We show that this representation is
irreducible and we compute its classical shadow, in the sense of earlier work
of the authors (arXiv:1206.1638).


title: The space of stability conditions for $A_3$-quiver

abstract:
  The author studied in \cite{shi} the covering map property of the local
homeomorphism associating to the space of stability conditions over the
$n$-Kronecker quiver. In this paper, we discuss the covering map property for
stability conditions over the Dynkin quiver of type $A_3$. The local
homeomorphism from a connected component of stability conditions over $A_3$ to
3-dimensional complex vector space becomes a covering map when we restrict it
to the complement of six codimension one subspaces.


title: Origin of indirect optical transitions in few-layer MoS2, WS2 and WSe2

abstract:
  It has been well established that single layer MX2 (M=Mo,W and X=S,Se) are
direct gap semiconductors with band edges coinciding at the K point in contrast
to their indirect gap multilayer counterparts. In few-layer MX2, there are two
valleys along the {\Gamma}-K line with similar energy. There is little
understanding on which of the two valleys forms the conduction band minimum
(CBM) in this thickness regime. We investigate the conduction band valley
structure in few-layer MX2 by examining the temperature-dependent shift of
indirect exciton PL. Hihgly anisotropic thermal expansion of the lattice and
corresponding evolution of the band structure result in distinct peak shift for
indirect transitions involving the K and {\Lambda} (midpoint along {\Gamma}-K)
valleys. We identify the origin of the indirect emission and concurrently
determine the relative energy of these valleys. Our results show that the two
valleys compete in energy in few-layer WSe2.


title: Proceedings First Workshop on Control Operators and their Semantics

abstract:
  The focus of the papers presented in this volume is on the interplay between
syntax and semantics in case of languages, namely the central question of what
a program means and how it does define the intended procedure. This is a
crucial issue especially in the case of control operators, since they are as
powerful as potentially obscure, and programs that use them are usually more
error-prone than purely declarative ones. The included contributions provide
perspectives on the topic of control operators via operational semantics of
formal calculi as well as type assignment systems, denotational semantics, game
semantics, category theory and logic.


title:
Temperature Evolution of Itinerant Ferromagnetism in SrRuO3 Probed by
  Optical Spectroscopy

abstract:
  The temperature ($T$) dependence of the optical conductivity spectra
$\sigma(\omega)$ of a single crystal SrRuO$_3$ thin film is studied over a $T$
range from 5 to 450 K. We observed significant $T$ dependence of the spectral
weights of the charge transfer and interband $d$-$d$ transitions across the
ferromagnetic Curie temperature ($T_c$ ~ 150 K). Such $T$ dependence was
attributed to the increase in the Ru spin moment, which is consistent with the
results of density functional theory calculations. $T$ scans of $\sigma(\Omega,
T)$ at fixed frequencies $\Omega$ reveal a clear $T^2$ dependence below $T_c$,
demonstrating that the Stoner mechanism is involved in the evolution of the
electronic structure. In addition, $\sigma(\Omega, T)$ continues to evolve at
temperatures above $T_c$, indicating that the local spin moment persists in the
paramagnetic state. This suggests that SrRuO$_3$ is an intriguing oxide system
with itinerant ferromagnetism.