title:
Estimating Treatment Effects using Multiple Surrogates: The Role of the
  Surrogate Score and the Surrogate Index

abstract:
  Estimating the long-term effects of treatments is of interest in many fields.
A common challenge in estimating such treatment effects is that long-term
outcomes are unobserved in the time frame needed to make policy decisions. One
approach to overcome this missing data problem is to analyze treatments effects
on an intermediate outcome, often called a statistical surrogate, if it
satisfies the condition that treatment and outcome are independent conditional
on the statistical surrogate. The validity of the surrogacy condition is often
controversial. Here we exploit that fact that in modern datasets, researchers
often observe a large number, possibly hundreds or thousands, of intermediate
outcomes, thought to lie on or close to the causal chain between the treatment
and the long-term outcome of interest. Even if none of the individual proxies
satisfies the statistical surrogacy criterion by itself, using multiple proxies
can be useful in causal inference. We focus primarily on a setting with two
samples, an experimental sample containing data about the treatment indicator
and the surrogates and an observational sample containing information about the
surrogates and the primary outcome. We state assumptions under which the
average treatment effect be identified and estimated with a high-dimensional
vector of proxies that collectively satisfy the surrogacy assumption, and
derive the bias from violations of the surrogacy assumption, and show that even
if the primary outcome is also observed in the experimental sample, there is
still information to be gained from using surrogates.


title:
Molecular Dynamics Simulation of Condensation on Nanostructured Surface
  in a Confined Space

abstract:
  Understanding heat transfer characteristics of phase change and enhancing
thermal energy transport in nanoscale are of great interest in both theoretical
and practical applications. In the present study, we investigated the nanoscale
vaporization and condensation by using molecular dynamics simulation. A cuboid
system is modeled by placing hot and cold walls in the bottom and top ends and
filling with working fluid between the two walls. By setting two different high
temperatures for the hot wall, we showed the normal and explosive vaporizations
and their impacts on thermal transport. For the cold wall, the cuboid
nanostructures with fixed height, varied length, width ranging from 4 to 20
layers, and an interval of 4 layers are constructed to study the effects of
condensation induced by different nanostructures. For vaporization, the results
showed that higher temperature of the hot wall led to faster transport of the
working fluid as a cluster moving from the hot wall to the cold wall. However,
excessive temperature of the hot wall causes explosive boiling, which seems not
good for the transport of heat due to the less phase change of working fluid.
For condensation, the results indicate that nanostructure facilitates
condensation, which could be affected not only by the increased surface area
but also by the distances between surfaces of the nanostructures and the cold
end. There is an optimal nanosctructure scheme which maximizes the phase change
rate of the entire system.


title:
Molecular environment, reverberation, and radiation from the pulsar wind
  nebula in CTA 1

abstract:
  We estimate the molecular mass around CTA 1 using data from Planck and the
Harvard CO survey. We observe that the molecular mass in the vicinity of the
complex is not enough to explain the TeV emission observed by VERITAS, even
under favorable assumptions for the cosmic-ray acceleration properties of the
supernova remnant. This supports the idea that the TeV emission comes from the
PWN. Here, we model the spectrum of the PWN at possible different stages of its
evolution, including both the dynamics of the PWN and the SNR and their
interaction via the reverse shock. We have included in the model the energy
lost via radiation by particles and the particles escape when computing the
pressure produced by the gas. This leads to an evolving energy partition, since
for the same instantaneous sharing of the injection of energy provided by the
rotational power, the field and the particles are affected differently by
radiation and losses. We present the model, and study in detail how the
spectrum of a canonical isolated PWN is affected during compression and
re-expansion and how this may impact on the CTA 1 case. By exploring the
phase-space of parameters that lead to radii in agreement with those observed,
we then analyze different situations that might represent the current stage of
the CTA 1 PWN, and discuss caveats and requirements of each one.


title:
Pricing occupation-time options in a mixed-exponential jump-diffusion
  model

abstract:
  In this short paper, in order to price occupation-time options, such as
(double-barrier) step options and quantile options, we derive various joint
distributions of a mixed-exponential jump-diffusion process and its occupation
times of intervals.


title:
Intersecting the dimension filtration with the slice one for (relative)
  motivic categories

abstract:
  In this paper we prove that the intersections of the levels of the dimension
filtration on Voevodsky's motivic complexes over a field $k$ with the levels of
the slice one are "as small as possible", i.e., that $Obj d_{\le
m}DM^{eff}_{-,R} \cap Obj DM^{eff}_{-,R} (i)=Obj d_{\le m-i} DM^{eff}_{-,R}
(i)$ (for $m,i\ge 0$ and $R$ being any coefficient ring in which the
exponential characteristic of $k$ invertible). This statement is applied to
prove that a conjecture of J. Ayoub is equivalent to a certain orthogonality
assumption. We also establish a vast generalization of our intersection result
to relative motivic categories (that are required to fulfil a certain list of
"axioms"). In the process we prove several new properties of relative motives
and of the so-called Chow weight structures for them.


title: Symmetry-protected non-Abelian braiding of Majorana Kramers' pairs

abstract:
  We develop the complete theory for non-Abelian braiding of Majorana Kramers'
pairs (MKPs) in time-reversal (TR) invariant topological superconductors. By
introducing an effective Hamiltonian approach to describe the braiding of MKPs,
we show that the non-Abelian braiding is protected when the effective
Hamiltonian exhibits a new TR like anti-unitary symmetry, which is satisfied if
the system is free of dynamical noise. Importantly, even the dynamical noise
may not cause error in braiding, unless the noise correlation function breaks a
dynamical TR symmetry, which generalizes the TR symmetry protection of MKPs to
dynamical regime. Moreover, the resulted error by noise is shown to be a higher
order effect, compared with the decoherence of Majorana qubits without TR
symmetry protection. These results show that the non-Abelian braiding of MKPs
is observable and may have versatile applications to future quantum computation
technologies.


title:
Characterising stellar halo populations I: An extended distribution
  function for halo K giants

abstract:
  We fit an Extended Distribution Function (EDF) to K giants in the Sloan
Extension for Galactic Understanding and Exploration (SEGUE) survey. These
stars are detected to radii ~80 kpc and span a wide range in [Fe/H]. Our EDF,
which depends on [Fe/H] in addition to actions, encodes the entanglement of
metallicity with dynamics within the Galaxy's stellar halo. Our
maximum-likelihood fit of the EDF to the data allows us to model the survey's
selection function. The density profile of the K giants steepens with radius
from a slope ~-2 to ~-4 at large radii. The halo's axis ratio increases with
radius from 0.7 to almost unity. The metal-rich stars are more tightly confined
in action space than the metal-poor stars and form a more flattened structure.
A weak metallicity gradient ~-0.001 dex/kpc, a small gradient in the dispersion
in [Fe/H] of ~0.001 dex/kpc, and a higher degree of radial anistropy in
metal-richer stars result. Lognormal components with peaks at ~-1.5 and ~-2.3
are required to capture the overall metallicity distribution, suggestive of the
existence of two populations of K giants. The spherical anisotropy parameter
varies between 0.3 in the inner halo to isotropic in the outer halo. If the
Sagittarius stream is included, a very similar model is found but with a
stronger degree of radial anisotropy throughout.


title: The subpower membership problem for semigroups

abstract:
  Fix a finite semigroup $S$ and let $a_1,\ldots,a_k, b$ be tuples in a direct
power $S^n$. The subpower membership problem (SMP) asks whether $b$ can be
generated by $a_1,\ldots,a_k$. If $S$ is a finite group, then there is a
folklore algorithm that decides this problem in time polynomial in $nk$. For
semigroups this problem always lies in PSPACE. We show that the SMP for a full
transformation semigroup on 3 letters or more is actually PSPACE-complete,
while on 2 letters it is in P. For commutative semigroups, we provide a
dichotomy result: if a commutative semigroup $S$ embeds into a direct product
of a Clifford semigroup and a nilpotent semigroup, then SMP(S) is in P;
otherwise it is NP-complete.


title:
The Formalization of The Arithmetic System on The Ground of The Atomic
  Logic

abstract:
  This paper is a continuation of the paper [16]. Namely, in [16] we have
introduced, among others, the definition of the atomic entailment and we have
constructed the system $\overset\sqcap S$, which is based on the atomic
entailment. In this paper we show that the classical Arithmetic can be based on
the Atomic Logic (see [17]).


title: M\"obius Invariants of Shapes and Images

abstract:
  Identifying when different images are of the same object despite changes
caused by imaging technologies, or processes such as growth, has many
applications in fields such as computer vision and biological image analysis.
One approach to this problem is to identify the group of possible
transformations of the object and to find invariants to the action of that
group, meaning that the object has the same values of the invariants despite
the action of the group. In this paper we study the invariants of planar shapes
and images under the M\"obius group $\mathrm{PSL}(2,\mathbb{C})$, which arises
in the conformal camera model of vision and may also correspond to neurological
aspects of vision, such as grouping of lines and circles. We survey properties
of invariants that are important in applications, and the known M\"obius
invariants, and then develop an algorithm by which shapes can be recognised
that is M\"obius- and reparametrization-invariant, numerically stable, and
robust to noise. We demonstrate the efficacy of this new invariant approach on
sets of curves, and then develop a M\"obius-invariant signature of grey-scale
images.


title: High energy scattering of Dirac particles on smooth potentials

abstract:
  The derivation of the Glauber type representation for the high energy
scattering amplitude of particles of spin 1/2 is given within the framework of
the Dirac equation in the Foldy Wouthuysen (FW) representation and
two-component formalism. The differential cross sections on the Yukawa and
Gaussian potentials are also considered and discussed.


title: Real-time topological image smoothing on shared memory parallel machines

abstract:
  Smoothing filter is the method of choice for image preprocessing and pattern
recognition. We present a new concurrent method for smoothing 2D object in
binary case. Proposed method provides a parallel computation while preserving
the topology by using homotopic transformations. We introduce an adapted
parallelization strategy called split, distribute and merge (SDM) strategy
which allows efficient parallelization of a large class of topological
operators including, mainly, smoothing, skeletonization, and watershed
algorithms. To achieve a good speedup, we cared about task scheduling.
Distributed work during smoothing process is done by a variable number of
threads. Tests on 2D binary image (512*512), using shared memory parallel
machine (SMPM) with 8 CPU cores (2 Xeon E5405 running at frequency of 2 GHz),
showed an enhancement of 5.2 thus a cadency of 32 images per second is
achieved.


title:
Factorization for groomed jet substructure beyond the next-to-leading
  logarithm

abstract:
  Jet grooming algorithms are widely used in experimental analyses at hadron
colliders to remove contaminating radiation from within jets. While the
algorithms perform a great service to the experiments, their intricate
algorithmic structure and multiple parameters has frustrated precision
theoretic understanding. In this paper, we demonstrate that one particular
groomer called soft drop actually makes precision jet substructure easier. In
particular, we derive a factorization formula for a large class of soft drop
jet substructure observables, including jet mass. The essential observation
that allows for this factorization is that, without the soft wide-angle
radiation groomed by soft drop, all singular contributions are collinear. The
simplicity and universality of the collinear limit in QCD allows us to show
that to all orders, the normalized differential cross section has no
contributions from non-global logarithms. It is also independent of process, up
to the relative fraction of quark and gluon jets. In fact, soft drop allows us
to define this fraction precisely. The factorization theorem also explains why
soft drop observables are less sensitive to hadronization than their ungroomed
counterparts. Using the factorization theorem, we resum the soft drop jet mass
to next-to-next-to-leading logarithmic accuracy. This requires calculating some
clustering effects that are closely related to corresponding effects found in
jet veto calculations. We match our resummed calculation to fixed order results
for both $e^+e^-\to$ dijets and $pp\to Z+j$ events, producing the first jet
substructure predictions (groomed or ungroomed) to this accuracy for the LHC.


title: Chemical separation of disc components using RAVE

abstract:
  We present evidence from the RAdial Velocity Experiment (RAVE) survey of
chemically separated, kinematically distinct disc components in the solar
neighbourhood. We apply probabilistic chemical selection criteria to separate
our sample into $\alpha$-low (`thin disc') and $\alpha$-high (`thick disc')
sequences. Using newly derived distances, which will be utilized in the
upcoming RAVE DR5, we explore the kinematic trends as a function of metallicity
for each of the disc components. For our $\alpha$-low disc, we find a negative
trend in the mean rotational velocity ($V_{\mathrm{\phi}}$) as a function of
iron abundance ([Fe/H]). We measure a positive gradient $\partial
V_{\mathrm{\phi}}$/$\partial$[Fe/H] for the $\alpha$-high disc, consistent with
results from high-resolution surveys. We also find differences between the
$\alpha$-low and $\alpha$-high discs in all three components of velocity
dispersion. We discuss the implications of an $\alpha$-low, metal-rich
population originating from the inner Galaxy, where the orbits of these stars
have been significantly altered by radial mixing mechanisms in order to bring
them into the solar neighbourhood. The probabilistic separation we propose can
be extended to other data sets for which the accuracy in [$\alpha$/Fe] is not
sufficient to disentangle the chemical disc components a priori. For such
datasets which will also have significant overlap with Gaia DR1, we can
therefore make full use of the improved parallax and proper motion data as it
becomes available to investigate kinematic trends in these chemical disc
components.


title: Towards universal hybrid star formation rate estimators

abstract:
  To compute the SFR of galaxies from the rest-frame UV it is essential to take
into account the obscuration by dust. To do so, one of the most popular methods
consists in combining the UV with the emission from the dust itself in the IR.
Yet, different studies have derived different estimators, showing that no such
hybrid estimator is truly universal. In this paper we aim at understanding and
quantifying what physical processes drive the variations between different
hybrid estimators. Doing so, we aim at deriving new universal UV+IR hybrid
estimators to correct the UV for dust attenuation, taking into account the
intrinsic physical properties of galaxies. We use the CIGALE code to model the
spatially-resolved FUV to FIR SED of eight nearby star-forming galaxies drawn
from the KINGFISH sample. This allows us to determine their local physical
properties, and in particular their UV attenuation, average SFR, average
specific SFR (sSFR), and their stellar mass. We then examine how hybrid
estimators depend on said properties. We find that hybrid UV+IR estimators
strongly depend on the stellar mass surface density (in particular at 70 and
100 micron) and on the sSFR (in particular at 24 micron and the TIR).
Consequently, the IR scaling coefficients for UV obscuration can vary by almost
an order of magnitude. This result contrasts with other groups who found
relatively constant coefficients with small deviations. We exploit these
variations to construct a new class of hybrid estimators based on observed UV
to near-IR colours and near-IR luminosity densities per unit area. We find that
they can reliably be extended to entire galaxies. The new estimators provide
better estimates of attenuation-corrected UV emission than classical hybrid
estimators. Naturally taking into account the variable impact of dust heated by
old stellar populations, they constitute a step towards universal estimators.


title: Linking Dense Gas from the Milky Way to External Galaxies

abstract:
  In a survey of 65 galaxies, Gao & Solomon (2004) found a tight linear
relation between the infrared luminosity ($L_{\rm{IR}}$, a proxy for the star
formation rate) and the HCN(1-0) luminosity ($L_{\rm{HCN}}$). Wu et al. (2005,
2010) found that this relation extends from these galaxies to the much less
luminous Galactic molecular high-mass star-forming clumps ($\sim$1 pc scales),
and posited that there exists a characteristic ratio $L_{\rm{IR}}$
/$L_{\rm{HCN}}$ for high-mass star-forming clumps. The Gao-Solomon relation for
galaxies could then be explained as a summation of large numbers of high-mass
star-forming clumps, resulting in the same $L_{\rm{IR}}$ /$L_{\rm{HCN}}$ ratio
for galaxies. We test this explanation and other possible origins of the
Gao-Solomon relation using high-density tracers (including HCN(1-0),
N$_2$H$^+$(1-0), HCO$^+$(1-0), HNC(1-0), HC$_3$N(10-9), and C$_2$H(1-0)) for
$\sim$300 Galactic clumps from the Millimetre Astronomy Legacy Team 90 GHz
(MALT90) survey. The MALT90 data show that the Gao-Solomon relation in galaxies
cannot be satisfactorily explained by the blending of large numbers of
high-mass clumps in the telescope beam. Not only do the clumps have a large
scatter in the $L_{\rm{IR}}$/$L_{\rm{HCN}}$ ratio, but also far too many
high-mass clumps are required to account for the Galactic IR and HCN
luminosities. We suggest that the scatter in the $L_{\rm{IR}}$/$L_{\rm{HCN}}$
ratio converges to the scatter of the Gao-Solomon relation at some size-scale
$\gtrsim$1 kpc. We suggest that the Gao-Solomon relation could instead result
from of a universal large-scale star formation efficiency, initial mass
function, core mass function, and clump mass function.


title:
Local Volume TiNy Titans: Gaseous Dwarf-Dwarf Interactions in the Local
  Universe

abstract:
  In this paper, we introduce the Local Volume TiNy Titans sample (LV-TNT),
which is a part of a larger body of work on interacting dwarf galaxies: TNT
(Stierwalt et al. 2015). This LV-TNT sample consists of 10 dwarf galaxy pairs
in the Local Universe (< 30 Mpc from Milky Way), which span mass ratios of
M_(*,1)/M_(*,2) < 20, projected separations < 100 kpc, and pair member masses
of log(M_*/M_Sun) < 9.9. All 10 LV-TNT pairs have resolved synthesis maps of
their neutral hydrogen, are located in a range of environments and captured at
various interaction stages. This enables us to do a comparative study of the
diffuse gas in dwarf-dwarf interactions and disentangle the gas lost due to
interactions with halos of massive galaxies, from the gas lost due to mutual
interaction between the dwarfs. We find that the neutral gas is extended in the
interacting pairs when compared to non-paired analogs, indicating that gas is
tidally pre-processed. Additionally, we find that the environment can shape the
HI distributions in the form of trailing tails and that the gas is not unbound
and lost to the surroundings unless the dwarf pair is residing near a massive
galaxy. We conclude that a nearby, massive host galaxy is what ultimately
prevents the gas from being reaccreted. Dwarf-dwarf interactions thus represent
an important part of the baryon cycle of low mass galaxies, enabling the
"parking" of gas at large distances to serve as a continual gas supply channel
until accretion by a more massive host.


title:
Benchmark Transiting Brown Dwarf LHS 6343 C: Spitzer Secondary Eclipse
  Observations Yield Brightness Temperature and mid-T Spectral Class

abstract:
  There are no field brown dwarf analogs with measured masses, radii, and
luminosities, precluding our ability to connect the population of transiting
brown dwarfs with measurable masses and radii and field brown dwarfs with
measurable luminosities and atmospheric properties. LHS 6343 C, a
weakly-irradiated brown dwarf transiting one member of an M+M binary in the
Kepler field, provides the first opportunity to probe the atmosphere of a
non-inflated brown dwarf with a measured mass and radius. Here, we analyze four
Spitzer observations of secondary eclipses of LHS 6343 C behind LHS 6343 A.
Jointly fitting the eclipses with a Gaussian process noise model of the
instrumental systematics, we measure eclipse depths of 1.06 \pm 0.21 ppt at 3.6
microns and 2.09 \pm 0.08 ppt at 4.5 microns, corresponding to brightness
temperatures of 1026 \pm 57 K and 1249 \pm 36 K, respectively. We then apply
brown dwarf evolutionary models to infer a bolometric luminosity log(L_star /
L_sun) = -5.16 \pm 0.04. Given the known physical properties of the brown dwarf
and the two M dwarfs in the LHS 6343 C system, these depths are consistent with
models of a 1100 K T dwarf at an age of 5 Gyr and empirical observations of
field T5-6 dwarfs with temperatures of 1070 \pm 130 K. We investigate the
possibility that the orbit of LHS 6343 C has been altered by the Kozai-Lidov
mechanism and propose additional astrometric or Rossiter-McLaughlin
measurements of the system to probe the dynamical history of the system.


title: Liberating exomoons in white dwarf planetary systems

abstract:
  Previous studies indicate that more than a quarter of all white dwarf (WD)
atmospheres are polluted by remnant planetary material, with some WDs being
observed to accrete the mass of Pluto in 10^6 years. The short sinking
timescale for the pollutants indicate that the material must be frequently
replenished. Moons may contribute decisively to this pollution process if they
are liberated from their parent planets during the post-main-sequence evolution
of the planetary systems. Here, we demonstrate that gravitational scattering
events among planets in WD systems easily triggers moon ejection. Repeated
close encounters within tenths of a planetary Hill radii are highly destructive
to even the most massive, close-in moons. Consequently, scattering increases
both the frequency of perturbing agents in WD systems, as well as the available
mass of polluting material in those systems, thereby enhancing opportunities
for collision and fragmentation and providing more dynamical pathways for
smaller bodies to reach the WD. Moreover, during intense scattering, planets
themselves have pericenters with respect to the WD of only a fraction of an AU,
causing extreme Hill-sphere contraction, and the liberation of moons into
WD-grazing orbits. Many of our results are directly applicable to exomoons
orbiting planets around main sequence stars.


title:
Circumstellar Dust, PAHs, and Stellar Populations in Early-Type
  Galaxies: Insights from GALEX and WISE

abstract:
  A majority of early-type galaxies contain interstellar dust, yet the origin
of this dust, and why the dust sometimes exhibits unusual polycyclic aromatic
hydrocarbon (PAH) ratios, remains a mystery. If the dust is internally
produced, it likely originates from the large number of AGB stars associated
with the old stellar population. We present GALEX and WISE elliptical aperture
photometry of $\sim310$ early-type galaxies with Spitzer mid-infrared
spectroscopy and/or ancillary data from ATLAS3D, to characterize their
circumstellar dust and the shape of the radiation field that illuminates the
interstellar PAHs. We find that circumstellar dust is ubiquitous in early-type
galaxies, which indicates some tension between stellar population age estimates
and models for circumstellar dust production in very old stellar populations.
We also use dynamical masses from ATLAS3D to show that WISE W1 (3.4 $\mu$m)
mass-to-light ratios are consistent with the initial mass function variation
found by previous work. While the stellar population differences in early-type
galaxies correspond to a range of radiation field shapes incident upon the
diffuse dust, the ratio of the ionization-sensitive $7.7\mu$m to $11.3\mu$m PAH
feature does not correlate with the shape of the radiation field, nor to
variations with the size-sensitive $11.3\mu$m to $17\mu$m ratio. The $7.7\mu$m
to $11.3\mu$m PAH ratio does tend to be smaller in galaxies with proportionally
greater $H_2$ emission, which is evidence that processing of primarily smaller
grains by shocks is responsible for the unusual ratios, rather than substantial
differences in the overall PAH size or ionization distribution.


title: Collinear Superspace

abstract:
  This letter provides a superfield based approach to constructing a collinear
slice of $\mathcal{N}$ = 1 superspace. The strategy is analogous to integrating
out anti-collinear fermionic degrees-of-freedom as was developed in the context
of soft-collinear effective theory. The resulting Lagrangian can be understood
as an integral over collinear superspace, where half the supercoordinates have
been integrated out. The application to $\mathcal{N}$ = 1 super Yang-Mills is
presented. Collinear superspace provides the foundation for future explorations
of supersymmetric soft-collinear effective theory.


title: On the MSSM Higgsino mass and fine tuning

abstract:
  It is often argued that low fine tuning in the MSSM necessarily requires a
rather light Higgsino. In this note we show that this need not be the case when
a more complete set of soft SUSY breaking mass terms are included. In
particular an Higgsino mass term, that correlates the $\mu-$term contribution
with the soft SUSY-breaking Higgsino masses, significantly reduces the fine
tuning even for Higgsinos in the TeV mass range where its relic abundance means
it can make up all the dark matter.


title:
Selection bias in dynamically-measured super-massive black hole samples:
  consequences for pulsar timing arrays

abstract:
  Supermassive black hole -- host galaxy relations are key to the computation
of the expected gravitational wave background (GWB) in the pulsar timing array
(PTA) frequency band. It has been recently pointed out that standard relations
adopted in GWB computations are in fact biased-high. We show that when this
selection bias is taken into account, the expected GWB in the PTA band is a
factor of about three smaller than previously estimated. Compared to other
scaling relations recently published in the literature, the median amplitude of
the signal at $f=1$yr$^{-1}$ drops from $1.3\times10^{-15}$ to
$4\times10^{-16}$. Although this solves any potential tension between
theoretical predictions and recent PTA limits without invoking other dynamical
effects (such as stalling, eccentricity or strong coupling with the galactic
environment), it also makes the GWB detection more challenging.


title:
Jet Substructure Classification in High-Energy Physics with Deep Neural
  Networks

abstract:
  At the extreme energies of the Large Hadron Collider, massive particles can
be produced at such high velocities that their hadronic decays are collimated
and the resulting jets overlap. Deducing whether the substructure of an
observed jet is due to a low-mass single particle or due to multiple decay
objects of a massive particle is an important problem in the analysis of
collider data. Traditional approaches have relied on expert features designed
to detect energy deposition patterns in the calorimeter, but the complexity of
the data make this task an excellent candidate for the application of machine
learning tools. The data collected by the detector can be treated as a
two-dimensional image, lending itself to the natural application of image
classification techniques. In this work, we apply deep neural networks with a
mixture of locally-connected and fully-connected nodes. Our experiments
demonstrate that without the aid of expert features, such networks match or
modestly outperform the current state-of-the-art approach for discriminating
between jets from single hadronic particles and overlapping jets from pairs of
collimated hadronic particles, and that such performance gains persist in the
presence of pileup interactions.


title: Novel kinematics from a custodially protected diphoton resonance

abstract:
  We study a simple, well-motivated model based on a custodial symmetry which
describes the tree-level production of a 750 GeV diphoton resonance from a
decay of a singly produced vector-like quark. The model has several novel
features. The identification of the resonance as an SU(2)$_R$ triplet provides
a symmetry explanation for suppression of its decays to hh, WW, and gg.
Moreover, the ratio of the 13 TeV to 8 TeV cross sections can be larger than
single production of a 750 GeV resonance, reaching ratios of up to 7 for TeV
scale vector-like quark masses. This eliminates any tension between the results
from Run I and Run II diphoton searches. Lastly, we study the kinematics of our
signal and conclude that the new production mechanism is consistent with
available experimental distributions in large regions of parameter space but,
depending on the mass of the new vector-like quarks, can be differentiated from
the background with more statistics.


title:
The Spectral Slope and Escape Fraction of Bright Quasars at $z \sim
  3.8$: the Contribution to the Cosmic UV Background

abstract:
  We use a sample of 1669 QSOs ($r<20.15$, $3.6<z<4.0$) from the BOSS survey to
study the intrinsic shape of their continuum and the Lyman continuum photon
escape fraction (f$_{esc}$), estimated as the ratio between the observed flux
and the expected intrinsic flux (corrected for the intergalactic medium
absorption) in the wavelength range 865-885 \AA\ rest-frame. Modelling the
intrinsic QSO continuum shape with a power-law,
$F_{\lambda}\propto\lambda^{-\gamma}$, we find a median $\gamma=1.30$ (with a
dispersion of $0.38$, no dependence on the redshift and a mild intrinsic
luminosity dependence) and a mean f$_{esc}=0.75$ (independent of the QSO
luminosity and/or redshift). The f$_{esc}$ distribution shows a peak around
zero and a long tail of higher values, with a resulting dispersion of $0.7$. If
we assume for the QSO continuum a double power-law shape (also compatible with
the data) with a break located at $\lambda_{\rm br}=1000$ \AA\ and a softening
$\Delta\gamma=0.72 $ at wavelengths shorter than $\lambda_{\rm br}$, the mean
f$_{esc}$ rises to $=0.82$. Combining our $\gamma$ and f$_{esc}$ estimates with
the observed evolution of the AGN luminosity function (LF) we compute the AGN
contribution to the UV ionizing background (UVB) as a function of redshift. AGN
brighter than one tenth of the characteristic luminosity of the LF are able to
produce most of it up $z\sim 3$, if the present sample is representative of
their properties. At higher redshifts a contribution of the galaxy population
is required. Assuming an escape fraction of Lyman continuum photons from
galaxies between $5.5$ and $7.6\%$, independent of the galaxy luminosity and/or
redshift, a remarkably good fit to the observational UVB data up to $z\sim 6$
is obtained. At lower redshift the extrapolation of our empirical estimate
agrees well with recent UVB observations, dispelling the so-called Photon
Underproduction Crisis.


title: Ringed Substructure and a Gap at 1 AU in the Nearest Protoplanetary Disk

abstract:
  We present long-baseline Atacama Large Millimeter/submillimeter Array (ALMA)
observations of the 870 micron continuum emission from the nearest gas-rich
protoplanetary disk, around TW Hya, that trace millimeter-sized particles down
to spatial scales as small as 1 AU (20 mas). These data reveal a series of
concentric ring-shaped substructures in the form of bright zones and narrow
dark annuli (1-6 AU) with modest contrasts (5-30%). We associate these features
with concentrations of solids that have had their inward radial drift slowed or
stopped, presumably at local gas pressure maxima. No significant
non-axisymmetric structures are detected. Some of the observed features occur
near temperatures that may be associated with the condensation fronts of major
volatile species, but the relatively small brightness contrasts may also be a
consequence of magnetized disk evolution (the so-called zonal flows). Other
features, particularly a narrow dark annulus located only 1 AU from the star,
could indicate interactions between the disk and young planets. These data
signal that ordered substructures on ~AU scales can be common, fundamental
factors in disk evolution, and that high resolution microwave imaging can help
characterize them during the epoch of planet formation.


title: Schwarzschild black hole as particle accelerator of spinning particles

abstract:
  It is shown that in the Schwarzschild background there exists direct
counterpart of the Ba\~{n}ados-Silk-West effect for spinning particles. This
means that if two particles collide near the black hole horizon, their energy
in the centre of mass frame can grow unbounded. In doing so, the crucial role
is played by so-called near-critical trajectories when particle's parameters
are almost fine-tuned. Direct scenario of the collision under discussion is
possible with restriction on the energy-to-mass ratio \thinspace
$E/m<\frac{1}{2\sqrt{3}}$ only. However, if one takes into account multiple
scattering, this becomes possible for $E\geq m$ as well.


title: Asymmetric Dark Matter Models and the LHC Diphoton Excess

abstract:
  The existence of dark matter (DM) and the origin of the baryon asymmetry are
persistent indications that the SM is incomplete. More recently, the ATLAS and
CMS experiments have observed an excess of diphoton events with invariant mass
of about 750 GeV. One interpretation of this excess is decays of a new spin-0
particle with a sizable diphoton partial width, e.g. induced by new heavy
weakly charged particles. These are also key ingredients in models cogenerating
asymmetric DM and baryons via sphaleron interactions and an initial particle
asymmetry. We explore what consequences the new scalar may have for models of
asymmetric DM that attempt to account for the similarity of the dark and
visible matter abundances.


title: Healthy degenerate theories with higher derivatives

abstract:
  In the context of classical mechanics, we study the conditions under which
higher-order derivative theories can evade the so-called Ostrogradsky
instability. More precisely, we consider general Lagrangians with second order
time derivatives, of the form $L(\ddot\phi^a,\dot\phi^a,\phi^a;\dot q^i,q^i)$
with $a = 1,\cdots, n$ and $i = 1,\cdots, m$. For $n=1$, assuming that the
$q^i$'s form a nondegenerate subsystem, we confirm that the degeneracy of the
kinetic matrix eliminates the Ostrogradsky instability. The degeneracy implies,
in the Hamiltonian formulation of the theory, the existence of a primary
constraint, which generates a secondary constraint, thus eliminating the
Ostrogradsky ghost. For $n>1$, we show that, in addition to the degeneracy of
the kinetic matrix, one needs to impose extra conditions to ensure the presence
of a sufficient number of secondary constraints that can eliminate all the
Ostrogradsky ghosts. When these conditions that ensure the disappearance of the
Ostrogradsky instability are satisfied, we show that the Euler-Lagrange
equations, which involve a priori higher order derivatives, can be reduced to a
second order system.


title:
How Density Environment Changes the Influence of the Dark Matter-Baryon
  Streaming Velocity on the Cosmological Structure Formation

abstract:
  We study the dynamical effect of relative velocities between dark matter and
baryonic fluids, which remained supersonic after the epoch of recombination.
The impact of this supersonic motion on the formation of cosmological
structures was first formulated by Tseliakhovich & Hirata (2010), in terms of
the linear theory of small-scale fluctuations coupled to large-scale, relative
velocities in mean-density regions. In their formalism, they limited the
large-scale density environment to be those of the global mean density. We
improve on their formulation by allowing variation in the density environment
as well as the relative velocities. This leads to a new type of coupling
between large-scale and small-scale modes. We find that the small-scale
fluctuation grows in a biased way: faster in the overdense environment and
slower in the underdense environment. We also find that the net effect on the
global power spectrum of the density fluctuation is to boost its overall
amplitude from the prediction by Tseliakhovich & Hirata (2010).
Correspondingly, the conditional mass function of cosmological halos and the
halo bias parameter are both affected in a similar way. The discrepancy between
our prediction and that by Tseliakhovich & Hirata (2010) is significant, and
therefore the related cosmology and high-redshift astrophysics should be
revisited. The mathematical formalism of this study can be used for generating
cosmological initial conditions of small-scale perturbations in generic,
overdense (underdense) background patches.


title:
Constraining turbulence mixing strength in transitional discs with
  planets using SPHERE and ALMA

abstract:
  We investigate the effect that the turbulent mixing strength parameter
$\alpha_{\rm{turb}}$ plays on near-infrared polarimetric and sub-millimetre
interferometric imaging observations of transitional discs (TDs) with a gap
carved by a planet. We generate synthetic observations of these objects with
ALMA and VLT/SPHERE-ZIMPOL by combining hydrodynamical, dust evolution,
radiative transfer and instrument models for values of
$\alpha_{\rm{turb}}=[10^{-4}, 10^{-3}, 10^{-2}]$. We find that, through a
combination of effects on the viscosity of the gas, the turbulent mixing and
dust evolution processes, $\alpha_{\rm{turb}}$ strongly affects the morphology
of the dust distribution that can be traced with these observations. We
constrain the value of $\alpha_{\rm{turb}}$ to be within an order of magnitude
of $10^{-3}$ in TD sources that show cavities in sub-mm continuum images while
featuring continuous distribution of dust or smaller cavities in
NIR-polarimetric images.


title:
Interaction-driven Lifshitz transition with dipolar fermions in optical
  lattices

abstract:
  Anisotropic dipole-dipole interactions between ultracold dipolar fermions
break the symmetry of the Fermi surface and thereby deform it. Here we
demonstrate that such a Fermi surface deformation induces a topological phase
transition -- so-called Lifshitz transition -- in the regime accessible to
present-day experiments. We describe the impact of the Lifshitz transition on
observable quantities such as the Fermi surface topology, the density-density
correlation function, and the excitation spectrum of the system. The Lifshitz
transition in ultracold atoms can be controlled by tuning the dipole
orientation and -- in contrast to the transition studied in crystalline solids
-- is completely interaction-driven.


title: Dimensional decoupling at continuous quantum critical Mott transitions

abstract:
  For continuous Mott metal-insulator transitions in layered two dimensional
systems, we demonstrate the phenomenon of dimensional decoupling: the system
behaves as a three-dimensional metal in the Fermi liquid side but as a stack of
decoupled two-dimensional layers in the Mott insulator. We show that the
dimensional decoupling happens at the Mott quantum critical point itself. We
derive the temperature dependence of the interlayer electric conductivity in
various crossover regimes near such a continuous Mott transition, and discuss
experimental implications.


title:
On the Pre-metric Formulation and Nonlinearization of Charge-free
  Electrodynamics

abstract:
  This paper presents a coordinate free pre-metric formulation of charge free
Maxwell-Minkowski electrodynamics, and of the developed by the authors
non-linear Extended Electrodynamics. First we introduce some formal relations
from multilinear algebra and differential geometry to be used further. Then we
recall and appropriately modify the existing pre-metric formulation of linear
charge free electrodynamics in pre-relativistic and relativistic forms as
preparation to turn to corresponding pre-metric nonlinearization. After some
preliminary examples and notes on nonlinearization, we motivate our view for
existence and explicit formulation of time stable subsystems of the physical
field objects considered. Section 5 presents the formal results of our approach
on the pre-metric nonlinear formulations in static case, in time-dependent
case, and in space-time formulation. In the Conclusion we give our general view
on "why and how to nonlinearize". The Appendix gives a possible formal
extension of our aproach to many subsystem field objects.


title: Heterotic T-fects, 6D SCFTs, and F-Theory

abstract:
  We study the $(1,0)$ six-dimensional SCFTs living on defects of non-geometric
heterotic backgrounds (T-fects) preserving a $E_7\times E_8$ subgroup of
$E_8\times E_8$. These configurations can be dualized explicitly to F-theory on
elliptic K3-fibered non-compact Calabi-Yau threefolds. We find that the
majority of the resulting dual threefolds contain non-resolvable singularities.
In those cases in which we can resolve the singularities we explicitly
determine the SCFTs living on the defect. We find a form of duality in which
distinct defects are described by the same IR fixed point. For instance, we
find that a subclass of non-geometric defects are described by the SCFT arising
from small heterotic instantons on ADE singularities.


title: Fragmentation of Neutron Star Matter

abstract:
  Background: Neutron stars are astronomical systems with nucleons submitted to
extreme conditions. Due to the long range coulomb repulsion between protons,
the system has structural inhomogeneities. These structural inhomogeneities
arise also in expanding systems, where the fragment distribution is highly
dependent on the thermodynamic conditions (temperature, proton fraction, ...)
and the expansion velocity.
  Purpose: We aim to find the different regimes of fragment distribution, and
the existence of infinite clusters.
  Method: We study the dynamics of the nucleons with a semiclassical molecular
dynamics model. Starting with an equilibrium configuration, we expand the
system homogeneously until we arrive to an asymptotic configuration (i. e. very
low final densities). We study the fragment distribution throughout this
expansion.
  Results: We found the typical regimes of the asymptotic fragment distribution
of an expansion: u-shaped, power law and exponential. Another key feature in
our calculations is that, since the interaction between protons is long range
repulsive, we do not have always an infinite fragment. We found that, as
expected, the faster the expansion velocity is, the quicker the infinite
fragment disappears.
  Conclusions: We have developed a novel graph-based tool for the
identification of infinite fragments, and found a transition from U-shaped to
exponential fragment mass distribution with increasing expansion rate.


title:
Lock-in range of classical PLL with impulse signals and
  proportionally-integrating filter

abstract:
  In the present work the model of PLL with impulse signals and active PI
filter in the signal's phase space is described. For the considered PLL the
lock-in range is computed analytically and obtained result are compared with
numerical simulations.


title: Partial Face Detection for Continuous Authentication

abstract:
  In this paper, a part-based technique for real time detection of users' faces
on mobile devices is proposed. This method is specifically designed for
detecting partially cropped and occluded faces captured using a smartphone's
front-facing camera for continuous authentication. The key idea is to detect
facial segments in the frame and cluster the results to obtain the region which
is most likely to contain a face. Extensive experimentation on a mobile dataset
of 50 users shows that our method performs better than many state-of-the-art
face detection methods in terms of accuracy and processing speed.


title: Gowers' Ramsey theorem for generalized tetris operations

abstract:
  We prove a generalization of Gowers' theorem for $\mathrm{FIN}_{k}$ where,
instead of the single tetris operation $T:\mathrm{FIN}_{k}\rightarrow
\mathrm{FIN}_{k-1}$, one considers all maps from $\mathrm{FIN}_{k}$ to
$\mathrm{FIN}_{j}$ for $0\leq j\leq k$ arising from nondecreasing surjections
$f:\left\{ 0,1,\ldots ,k+1\right\} \rightarrow \left\{ 0,1,\ldots ,j+1\right\}
$. This answers a question of Barto\v{s}ov\'{a} and Kwiatkowska. We also prove
a common generalization of such a result and the Galvin--Glazer--Hindman
theorem on finite products, in the setting of layered partial semigroups
introduced by Farah, Hindman, and McLeod.


title: SUSY at the LHC without Missing P_T

abstract:
  We consider a specific class of events of the SUSY particle production at the
LHC without missing p_T. Namely, we discuss the chargino pair production with a
further decay into the W-boson and the neutralino when the masses of the
chargino and neutralino differ by 80-90 GeV. In this case, in the final state
one has two Ws and missing E_T but no missing P_T. The produced neutralinos are
just boosted along Ws. For a demonstration we consider the MSSM with
non-universal gaugino masses. In this case, such events are quite probable in
the region of parameter space where the lightest chargino and neutralino are
mostly gauginos. The excess in the W production cross-section reach about 10 %
over the Standard Model background. We demonstrate that the LHC experiments,
which presently measure the WW production cross section at the 8 % level can
probe chargino mass around 110 GeV within the suggested scenario, which is not
accessible via other searches. If the precision of WW cross section measurement
at the LHC will achieve the 3 % level, then it would probe chargino masses up
to about 150 GeV within the no missing P_T scenario.


title:
Quantum Monte Carlo analysis of a charge ordered insulating
  antiferromagnet: the Ti$_4$O$_7$ Magn\'eli phase

abstract:
  The Magn\'eli phase Ti$_4$O$_7$ is an important transition metal oxide with a
wide range of applications because of its interplay between charge, spin, and
lattice degrees of freedom. At low temperatures, it has non-trivial magnetic
states very close in energy, driven by electronic exchange and correlation
interactions. We have examined three low-lying states, one ferromagnetic and
two antiferromagnetic, and calculated their energies as well as Ti spin moment
distributions using highly accurate Quantum Monte Carlo methods. We compare our
results to those obtained from density functional theory-based methods that
include approximate corrections for exchange and correlation. Our results
confirm the nature of the states and their ordering in energy, as compared with
density-functional theory methods. However, the energy differences and spin
distributions differ. A detailed analysis suggests that non-local
exchange-correlation functionals, in addition to other approximations such as
LDA+U to account for correlations, are needed to simultaneously obtain better
estimates for spin moments, distributions, energy differences and energy gaps.


title:
Roche tomography of cataclysmic variables - VII. The long-term magnetic
  activity of AE Aqr

abstract:
  We present a long-term study of the secondary star in the cataclysmic
variable AE~Aqr, using Roche tomography to indirectly image starspots on the
stellar surface spanning 8~years of observations. The 7 maps show an abundance
of spot features at both high and low latitudes. We find that all maps have at
least one large high-latitude spot region, and we discuss its complex evolution
between maps, as well as its compatibility with current dynamo theories.
Furthermore, we see the apparent growth in fractional spot coverage,
$f_{\mathrm{s}}$, around $45^{\circ}$~latitude over the duration of
observations, with a persistently high $f_{\mathrm{s}}$ near latitudes of
$20^{\circ}$. These bands of spots may form as part of a magnetic activity
cycle, with magnetic flux tubes emerging at different latitudes, similar to the
`butterfly' diagram for the Sun. We discuss the nature of flux tube emergence
in close binaries, as well as the activity of AE~Aqr in the context of other
stars.


title:
Nonaffine deformation under compression and decompression of a
  flow-stabilized solid

abstract:
  Understanding the particle-scale transition from elastic deformation to
plastic flow is central to making predictions about the bulk material
properties and response of disordered materials. To address this issue, we
perform experiments on flow-stabilized solids composed of micron-scale spheres
within a microfluidic channel, in a regime where particle inertia is
negligible. Each solid heap exists within a stress gradient imposed by the
flow, and we track the positions of particles in response to single impulses of
fluid-driven compression or decompression. We find that the resulting
deformation field is well-decomposed into an affine field, with a constant
strain profile throughout the solid, and a non-affine field. The magnitude of
this non-affine response decays with the distance from the free surface in the
long-time limit, suggesting that the distance from jamming plays a significant
role in controlling the length scale of plastic flow. Finally, we observe that
compressive pulses create more rearrangements than decompressive pulses, an
effect that we quantify using the $D^2_\mathrm{min}$ statistic for non-affine
motion. Unexpectedly, the time scale for the compression response is shorter
than for decompression at the same strain (but unequal pressure), providing
insight into the coupling between deformation and cage-breaking.


title: Non-Detection of Nova Shells Around Asynchronous Polars

abstract:
  Asynchronous polars (APs) are accreting white dwarfs (WDs) that have
different WD and orbital angular velocities, unlike the rest of the known
polars, which rotate synchronously (i.e., their WD and orbital angular
velocities are the same). Past nova eruptions are the predicted cause of the
asynchronicity, in part due to the fact that one of the APs, V1500 Cyg, was
observed to undergo a nova eruption in 1975. We used the Southern African Large
Telescope 10m class telescope and the MDM 2.4m Hiltner telescope to search for
nova shells around three of the remaining four APs (V1432 Aql, BY Cam, and CD
Ind) as well as one Intermediate Polar with a high asynchronicity (EX Hya). We
found no evidence of nova shells in any of our images. We therefore cannot say
that any of the systems besides V1500 Cyg had nova eruptions, but because not
all post-nova systems have detectable shells, we also cannot exclude the
possibility of a nova eruption occurring in any of these systems and knocking
the rotation out of sync.


title: Vortex driven phase transition in Topologically Massive QED

abstract:
  There is chiral like symmetry for 4-component massless fermion in
(2+1)-dimensional gauge theory.Since QED$_{3}$ with Chern-Simons term contains
vortex solution for vector potential,one may expect vortex driven phase
transition as Kosterlitz-Thouless type where chiral condensate is washed away
at zero temperature.To study this possibility,we evaluate the fermion
propagator by Dyson-Schwinger equation numerically and spectral function
analytically in the Landau gauge.For quenched case we adopt Ball-Chiu vertex to
keep gauge invariance of the results.The critical value of topological
mass,above which chiral condensate washed away, turned out to be
$O(10^{-2})e^{2}$ at least for weak coupling in both cases.


title:
Dipolar phase transitions in the cavity with Majorana populated
  Josephson junctions

abstract:
  We found that QED in the lowest eigenstate of the microwave-cavity,
capacitively coupled with Majorana populated Josephson junctions array, is
described with an effective $\phi^{4}$ model emerging in the finite domain of
the system parameters. Strong anharmonicity of the cavity mode arises due to
electric-dipole phase transition facilitated by the single-electron zero mode
and Cooper pair tunneling between superconducting islands. An instantonic
meandering of the electromagnetic field potential at finite temperatures is
predicted.


title: Dynamical invariance for random matrices

abstract:
  We consider a general Langevin dynamics for the one-dimensional N-particle
Coulomb gas with confining potential $V$ at temperature $\beta$. These dynamics
describe for $\beta=2$ the time evolution of the eigenvalues of $N\times N$
random Hermitian matrices. The equilibrium partition function -- equal to the
normalization constant of the Laughlin wave function in fractional quantum Hall
effect -- is known to satisfy an infinite number of constraints called Virasoro
or loop constraints. We introduce here a dynamical generating function on the
space of random trajectories which satisfies a large class of constraints of
geometric origin. We focus in this article on a subclass induced by the
invariance under the Schr\"odinger-Virasoro algebra.

categories: math-ph cond-mat.stat-mech hep-th math.MP


title:
Experimental demonstration of binary shaped pupil mask coronagraphs for
  telescopes with obscured pupils

abstract:
  We present the fabrication and experimental demonstration of three
free-standing binary shaped pupil mask coronagraphs, which are applicable for
telescopes with partially obscured pupils. Three masks, designed to be
complementary (labeled Mask-A, Mask-B, and Mask-C), were formed in 5 micron
thick nickel. The design of Mask-A is based on a one-dimensional barcode mask.
The design principle of Mask-B is similar, but has a smaller inner working
angle and a lower contrast than Mask-A. Mask-C is based on a concentric ring
mask and provides the widest dark region and a symmetric point spread function.
Mask-A and Mask-C were both designed to produce a flexibly tailored dark region
(i.e., non-uniform contrast). The contrast was evaluated using a light source
comprising a broadband super-luminescent light-emitting diode with a center
wavelength of 650 nm, and the measurements were carried out in a large vacuum
chamber. Active wavefront control was not applied in this work. The
coronagraphic images obtained by experiment were mostly consistent with the
designs. The contrast of Mask-A within the ranges 3.3 - 8 lambda/D and 8 - 12
lambda/D was ~10^{-4} - 10^{-7} and ~10^{-7}, respectively, where lambda is the
wavelength and D is the pupil diameter. The contrast close to the center of
Mask-B was ~10^{-4} and that of Mask-C over an extended field of view (5 - 25
lambda/D) was ~10^{-5} - 10^{-6}. The effect of tilting the masks was
investigated, and found to be irrelevant at the ~10^{-7} contrast level.
Therefore the masks can be tilted to avoid ghosting. These high-contrast
free-standing masks have the potential to enable coronagraphic imaging over a
wide wavelength range using both ground-based and space-borne general-purpose
telescopes with pupil structures not specifically designed for coronagraphy.


title:
Vogel-Fulcher-Tammann Freezing of a Thermally Fluctuating Artificial
  Spin Ice Probed by X-ray Photon Correlation Spectroscopy

abstract:
  We report on the crossover from the thermal to athermal regime of an
artificial spin ice formed from a square array of magnetic islands whose
lateral size, 30~nm~$\times$~70~nm, is small enough that they are
superparamagnetic at room temperature. We used resonant magnetic soft x-ray
photon correlation spectroscopy (XPCS) as a method to observe the time-time
correlations of the fluctuating magnetic configurations of spin ice during
cooling, which are found to slow abruptly as a freezing temperature $T_0 = 178
\pm 5$~K is approached. This slowing is well-described by a
Vogel-Fulcher-Tammann law, implying that the frozen state is glassy, with the
freezing temperature being commensurate with the strength of magnetostatic
interaction energies in the array. The activation temperature, $T_\mathrm{A} =
40 \pm 10$~K, is much less than that expected from a Stoner-Wohlfarth coherent
rotation model. Zero-field-cooled/field-cooled magnetometry reveals a freeing
up of fluctuations of states within islands above this temperature, caused by
variation in the local anisotropy axes at the oxidised edges. This
Vogel-Fulcher-Tammann behavior implies that the system enters a glassy state on
freezing, which is unexpected for a system with a well-defined ground state.


title:
On the Secure Degrees of Freedom of the K-user MAC and 2-user
  Interference Channels

abstract:
  We investigate the secure degrees of freedom (SDoF) of the K-user MIMO
multiple access (MAC) and the two user MIMO interference channel. An unknown
number of eavesdroppers are trying to decode the messages sent by the
transmitters. Each eavesdropper is equipped with a number of antennas less than
or equal to a known value NE. The legitimate transmitters and receivers are
assumed to have global channel knowledge. We present the sum SDoF of the two
user MIMO interference channel. We derive an upperbound on the sum SDoF of the
K-user MAC channel and present an achievable scheme that partially meets the
derived upperbound.


title: Extended symmetry analysis of generalized Burgers equations

abstract:
  Using advanced classification techniques, we carry out the extended symmetry
analysis of the class of generalized Burgers equations of the form
$u_t+uu_x+f(t,x)u_{xx}=0$. This enhances all the previous results on symmetries
of these equations and includes the description of admissible transformations,
Lie symmetries, Lie and nonclassical reductions, conservation laws, potential
admissible transformations and potential symmetries. The study is based on the
fact that the class is normalized, and its equivalence group is
finite-dimensional.


title:
Effects of Slotted Structures on Nonlinear Characteristics of Natural
  Convection in a Cylinder with an Internal Concentric Slotted Annulus

abstract:
  Natural convection in a cylinder with an internally slotted annulus was
solved by SIMPLE algorithm, and the effects of different slotted structures on
nonlinear characteristics of natural convection were investigated. The results
show that the equivalent thermal conductivity Keq increases with Rayleigh
number, and reaches the maximum in the vertical orientation. Nonlinear results
were obtained by simulating the fluid flow at different conditions. With
increasing Rayleigh number, heat transfer is intensified and the state of heat
transfer changes from the steady to unsteady. We investigated different slotted
structures effects on natural convection, and analyze the corresponding
nonlinear characteristics.


title: Co-t-structures: The First Decade

abstract:
  Co-t-structures were introduced about ten years ago as a type of mirror image
of t-structures. Like t-structures, they permit to divide an object in a
triangulated category T into a "left part" and a "right part", but there are
crucial differences. For instance, a bounded t-structure gives rise to an
abelian subcategory of T, while a bounded co-t-structure gives rise to a
so-called silting subcategory.
  This brief survey will emphasise three philosophical points. First, bounded
t-structures are akin to the canonical example of "soft" truncation of
complexes in the derived category. Secondly, bounded co-t-structures are akin
to the canonical example of "hard" truncation of complexes in the homotopy
category.
  Thirdly, a triangulated category T may be skewed towards t-structures or
co-t-structures, in the sense that one type of structure is more useful than
the other for studying T. In particular, we think of derived categories as
skewed towards t-structures, and of homotopy categories as skewed towards
co-t-structures.


title:
Decreasing groundwater quality at Cisadane riverbanks:
  groundwater-surface water approach

abstract:
  The decreasing of groundwater quality has been the major issue in Tangerang
area. One of the key process is the interaction between groundwater and
Cisadane river water, which flows over volcanic deposits of Bojongmanik Fm,
Genteng Fm, Tuf Banten, and Alluvial Fan. The objective of this study is to
unravel such interactions based on the potentiometric mapping in the riverbank.
We had 60 stop sites along the riverbank for groundwater and river water level
observations, and chemical measurements (TDS, EC, temp, and pH). Three river
water gauge were also analyzed to see the fluctuations.
  We identified three types of hydrodynamic relationships with fairly low flow
gradients: effluent flow at Segmen I (Kranggan - Batuceper) with 0.2-0.25
gradient, perched flow at Segmen II (Batuceper-Kalibaru) with gradient
0.2-0.25, and influent flow at Segmen III (Kalibaru-Tanjungburung) with
gradient 0.15-0.20. Such low flow gradient is controlled by the moderate to low
morphological slope in the area. The gaining and losing stream model were also
supported by the river water fluctuation data. TDS and EC readings increased
more than 40$\%$ from upstream to downstream. At some points the both
measurements were two times higher than the permissible limits, along with the
drops of pH values at those areas.
  This study shows the very close interaction between Cisadane river water and
groundwater in the riverbank. Therefore the authorities need to be managed the
areas with a very strict regulations related to the small and large scale
industries located near by the river.


title: Clinical Information Extraction via Convolutional Neural Network

abstract:
  We report an implementation of a clinical information extraction tool that
leverages deep neural network to annotate event spans and their attributes from
raw clinical notes and pathology reports. Our approach uses context words and
their part-of-speech tags and shape information as features. Then we hire
temporal (1D) convolutional neural network to learn hidden feature
representations. Finally, we use Multilayer Perceptron (MLP) to predict event
spans. The empirical evaluation demonstrates that our approach significantly
outperforms baselines.


title: Deep Networks with Stochastic Depth

abstract:
  Very deep convolutional networks with hundreds of layers have led to
significant reductions in error on competitive benchmarks. Although the
unmatched expressiveness of the many layers can be highly desirable at test
time, training very deep networks comes with its own set of challenges. The
gradients can vanish, the forward flow often diminishes, and the training time
can be painfully slow. To address these problems, we propose stochastic depth,
a training procedure that enables the seemingly contradictory setup to train
short networks and use deep networks at test time. We start with very deep
networks but during training, for each mini-batch, randomly drop a subset of
layers and bypass them with the identity function. This simple approach
complements the recent success of residual networks. It reduces training time
substantially and improves the test error significantly on almost all data sets
that we used for evaluation. With stochastic depth we can increase the depth of
residual networks even beyond 1200 layers and still yield meaningful
improvements in test error (4.91% on CIFAR-10).


title:
Estimating the cost of generic quantum pre-image attacks on SHA-2 and
  SHA-3

abstract:
  We investigate the cost of Grover's quantum search algorithm when used in the
context of pre-image attacks on the SHA-2 and SHA-3 families of hash functions.
Our cost model assumes that the attack is run on a surface code based
fault-tolerant quantum computer. Our estimates rely on a time-area metric that
costs the number of logical qubits times the depth of the circuit in units of
surface code cycles. As a surface code cycle involves a significant classical
processing stage, our cost estimates allow for crude, but direct, comparisons
of classical and quantum algorithms.
  We exhibit a circuit for a pre-image attack on SHA-256 that is approximately
$2^{153.8}$ surface code cycles deep and requires approximately $2^{12.6}$
logical qubits. This yields an overall cost of $2^{166.4}$
logical-qubit-cycles. Likewise we exhibit a SHA3-256 circuit that is
approximately $2^{146.5}$ surface code cycles deep and requires approximately
$2^{20}$ logical qubits for a total cost of, again, $2^{166.5}$
logical-qubit-cycles. Both attacks require on the order of $2^{128}$ queries in
a quantum black-box model, hence our results suggest that executing these
attacks may be as much as $275$ billion times more expensive than one would
expect from the simple query analysis.


title: Regular colorings and factors of regular graphs

abstract:
  An $(r-1,1)$-coloring of an $r$-regular graph $G$ is an edge coloring such
that each vertex is incident to $r-1$ edges of one color and $1$ edge of a
different color. In this paper, we completely characterize all $4$-regular
pseudographs (graphs that may contain parallel edges and loops) which do not
have a $(3,1)$-coloring. An $\{r-1,1\}$-factor of an $r$-regular graph is a
spanning subgraph in which each vertex has degree either $r-1$ or $1$. We prove
various conditions that that must hold for any vertex-minimal $5$-regular
pseudographs without $(4,1)$-colorings or without $\{4,1\}$-factors. Finally,
for each $r\geq 6$ we construct graphs that are not $(r-1,1)$-colorable and,
more generally, are not $(r-t,t)$-colorable for small $t$.


title:
Prethermalization and universal dynamics in near-integrable quantum
  systems

abstract:
  We review the recent progress in the understanding of the relaxation of
isolated near-integrable quantum many-body systems. Focusing on
prethermalization and universal dynamics following a quench, we describe the
experiments with ultracold atomic gases that illustrate these phenomena and
summarize the essential theoretical concepts employed to interpret them. Our
discussion highlights the key topics that link the different approaches to this
interdisciplinary field, including the generalized Gibbs ensemble, non-thermal
fixed points, critical slowing and universal scaling. Finally, we point to new
experimental challenges demonstrating these fundamental features of many-body
quantum systems out of equilibrium.

categories: cond-mat.quant-gas cond-mat.stat-mech hep-th quant-ph


title: Multi-Metric Energy Efficient Routing in Mobile Ad-Hoc Networks

abstract:
  Increasing network lifetime by reducing energy consumption across the network
is one of the major concerns while designing routing protocols for Mobile
Ad-Hoc Networks. In this paper, we investigate the main reasons that lead to
energy depletion and we introduce appropriate routing metrics in the routing
decision scheme to mitigate their effect and increase the network lifetime. For
our routing scheme, we take into consideration multiple layer parameters, such
as MAC queue utilization, node degree and residual energy. We integrate our
multi-metric routing scheme into OLSR, a standard MANET proactive routing
protocol. We evaluate via simulations in NS3 the protocol modifications under a
range of different static and mobile scenarios. The main observations are that
in static and low mobility scenarios our modified routing protocol leads to a
significant increase (5\%-20\%) in network lifetime compared to standard OLSR
and slightly better performance in terms of Packet Delivery Ratio (PDR).


title:
A finite-dimensional Lie algebra arising from a Nichols algebra of
  diagonal type (rank 2)

abstract:
  Let $\mathcal{B}_{\mathfrak{q}}$ be a finite-dimensional Nichols algebra of
diagonal type corresponding to a matrix $\mathfrak{q} \in \mathbf{k}^{\theta
\times \theta}$, where $\mathbf{k}$ is an algebraically closed field of
characteristic 0. Let $\mathcal{L}_{\mathfrak{q}}$ be the Lusztig algebra
associated to $\mathcal{B}_{\mathfrak{q}}$, see
http://arxiv.org/abs/1501.04518. We present $\mathcal{L}_{\mathfrak{q}}$ as an
extension (as braided Hopf algebras) of $\mathcal{B}_{\mathfrak{q}}$ by
$\mathfrak Z_{\mathfrak{q}}$ where $\mathfrak Z_{\mathfrak{q}}$ is isomorphic
to the universal enveloping algebra of a Lie algebra $\mathfrak
n_{\mathfrak{q}}$. We compute the Lie algebra $\mathfrak n_{\mathfrak{q}}$ when
$\theta = 2$.


title: Optimal rates for total variation denoising

abstract:
  Motivated by its practical success, we show that the two-dimensional total
variation denoiser satisfies a sharp oracle inequality that leads to near
optimal rates of estimation for a large class of image models such as
bi-isotonic, H\"older smooth and cartoons. Our analysis hinges on properties of
the unnormalized Laplacian of the two-dimensional grid such as eigenvector
delocalization and spectral decay. We also present extensions to more than two
dimensions as well as several other graphs.


title: Gromov-Witten theory of toroidal orbifolds and GIT wall-crossing

abstract:
  Toroidal 3-orbifolds $(S^1)^6/G$, for $G$ a finite group, were some of the
earliest examples of Calabi-Yau 3-orbifolds to be studied in string theory.
While much mathematical progress towards the predictions of string theory has
been made in the meantime, most of it has dealt with hypersurfaces in toric
varieties. As a result, very little is known about curve-counting theories on
toroidal orbifolds. In this paper, we initiate a program to study mirror
symmetry and the Landau-Ginzburg/Calabi-Yau (LG/CY) correspondence for toroidal
orbifolds. We focus on the simplest example $[E^3/\mu_3],$ where
$E\subseteq\mathbb{P}^2$ is the elliptic curve $\mathbb{V}(x_0^3+x_1^3+x_2^3).$
We study this orbifold from the point of GIT wall-crossing using the gauged
linear sigma model, a collection of moduli spaces generalizing spaces of stable
maps. Our main result is a mirror symmetry theorem that applies simultaneously
to the different GIT chambers. Using this, we analyze wall-crossing behavior to
obtain an LG/CY correspondence relating the genus-zero Gromov-Witten invariants
of $[E^3/\mu_3]$ to generalized Fan-Jarvis-Ruan-Witten invariants.


title: Mutual Dimension and Random Sequences

abstract:
  If $S$ and $T$ are infinite sequences over a finite alphabet, then the lower
and upper mutual dimensions $mdim(S:T)$ and $Mdim(S:T)$ are the upper and lower
densities of the algorithmic information that is shared by $S$ and $T$. In this
paper we investigate the relationships between mutual dimension and coupled
randomness, which is the algorithmic randomness of two sequences $R_1$ and
$R_2$ with respect to probability measures that may be dependent on one
another. For a restricted but interesting class of coupled probability measures
we prove an explicit formula for the mutual dimensions $mdim(R_1:R_2)$ and
$Mdim(R_1:R_2)$, and we show that the condition $Mdim(R_1:R_2) = 0$ is
necessary but not sufficient for $R_1$ and $R_2$ to be independently random.
  We also identify conditions under which Billingsley generalizations of the
mutual dimensions $mdim(S:T)$ and $Mdim(S:T)$ can be meaningfully defined; we
show that under these conditions these generalized mutual dimensions have the
"correct" relationships with the Billingsley generalizations of $dim(S)$,
$Dim(S)$, $dim(T)$, and $Dim(T)$ that were developed and applied by Lutz and
Mayordomo; and we prove a divergence formula for the values of these
generalized mutual dimensions.


title:
New Planetary Systems from the Calan-Hertfordshire Extrasolar Planet
  Search

abstract:
  We report the discovery of eight new giant planets, and updated orbits for
four known planets, orbiting dwarf and subgiant stars using the CORALIE, HARPS,
and MIKE instruments as part of the Calan-Hertfordshire Extrasolar Planet
Search. The planets have masses in the range 1.1-5.4MJs, orbital periods from
40-2900 days, and eccentricities from 0.0-0.6. They include a double-planet
system orbiting the most massive star in our sample (HD147873), two eccentric
giant planets (HD128356b and HD154672b), and a rare 14 Herculis analogue
(HD224538b). We highlight some population correlations from the sample of
radial velocity detected planets orbiting nearby stars, including the mass
function exponential distribution, confirmation of the growing body of evidence
that low-mass planets tend to be found orbiting more metal-poor stars than
giant planets, and a possible period-metallicity correlation for planets with
masses >0.1MJ, based on a metallicity difference of 0.16 dex between the
population of planets with orbital periods less than 100 days and those with
orbital periods greater than 100 days.


title: Polyharmonic $k-$Hessian equations in $\mathbb{R}^N$

abstract:
  This work is focused on the study of the nonlinear elliptic higher order
equation \begin{equation}\nonumber \left( -\Delta \right)^m u = S_k[-u] +
\lambda f, \qquad x \in \mathbb{R}^N, \end{equation} where the $k-$Hessian
$S_k[u]$ is the $k^{\mathrm{th}}$ elementary symmetric polynomial of
eigenvalues of the Hessian matrix of the solution and the datum $f$ belongs to
a suitable functional space. This problem is posed in $\mathbb{R}^N$ and we
prove the existence of at least one solution by means of topological fixed
point methods for suitable values of $m \in \mathbb{N}$. Questions related to
the regularity of the solutions and extensions of these results to the nonlocal
setting are also addressed. On the way to construct these proofs, some
technical results such as a fixed point theorem and a refinement of the
critical Sobolev embedding, which could be of independent interest, are
introduced.


title:
Optical trapping and control of nanoparticles inside evacuated hollow
  core photonic crystal fibers

abstract:
  We demonstrate an optical conveyor belt for levitated nano-particles over
several centimeters inside both air-filled and evacuated hollow-core photonic
crystal fibers (HCPCF). Detection of the transmitted light field allows
three-dimensional read-out of the particle center-of-mass motion. An additional
laser enables axial radiation pressure based feedback cooling over the full
fiber length. We show that the particle dynamics is a sensitive local probe for
characterizing the optical intensity profile inside the fiber as well as the
pressure distribution along the fiber axis. In contrast to previous indirect
measurement methods we find a linear pressure dependence inside the HCPCF
extending over three orders of magnitude from 0.2 mbar to 100 mbar. A targeted
application is the controlled delivery of nano-particles from ambient pressure
into medium vacuum.


title:
Quantum Size Effects in the Terahertz Nonlinear Response of Metallic
  Armchair Graphene Nanoribbons

abstract:
  We use time dependent perturbation theory to study quantum size effects on
the terahertz nonlinear response of metallic graphene armchair nanoribbons of
finite length under an applied electric field. Our work shows that quantization
due to the finite length of the nanoribbon, the applied field profile, and the
broadening of the graphene spectrum all play a significant role in the
resulting nonlinear conductances. In certain cases, these effects can
significantly enhance the nonlinearity over that for infinitely-long metallic
armchair graphene nanoribbon.


title:
Observing spin Hall effect of pseudo-thermal light through weak
  measurement

abstract:
  It is well known that the spin Hall effect of light (SHEL) can be easily
observed via weak measurement by the dark strip resulted from the splitting of
different polarization components. We find that the SHEL of partially coherent
beam (PCB) also has similar phenomenon. However, the existence of the dark
strip in the SHEL of PCB can not be properly justified by considering the beam
as a statistical assemble of coherent speckles. Also, the dark strip of PCB is
not purely dark. By analyzing the autocorrelation of the central dark strip
part of the SHEL of PCB, we show that SHEL of PCB is essentially the direct
result of overlapping coherent speckles' SHEL. Then we further prove our
conclusion by adjusting the converging level and the incident angle of the
beam. Finally, we develop a qualitative theory by taking the intensity
distribution of PCB into account, to fully clarify the SHEL of PCB. The
feasibility of our theory to Goos-H\"anchen (GH) scenario is also demonstrated.


title:
Robust Hybrid Image Watermarking based on Discrete Wavelet and Shearlet
  Transforms

abstract:
  With the growth of digital networks such as the Internet, digital media have
been explosively developed in e-commerce and online services. This causes
problems such as illegal copy and fake ownership. Watermarking is proposed as
one of the solutions to such cases. Among different watermarking techniques,
the wavelet transform has been used more because of its good ability in
modeling the human visual system. Recently, Shearlet transform as an extension
of Wavelet transform which is based on multi-resolution and multi-directional
analysis is introduced. The most important feature of this transform is the
appropriate representation of image edges. In this paper a hybrid scheme using
Discrete Wavelet Transform (DWT) and Discrete Shearlet Transform (DST) is
presented. In this way, the host image is decomposed using DWT, and then its
low frequency sub-band is decomposed by DST. After that, the bidiagonal
singular value decomposition (BSVD) is applied on the selected sub-band from
Shearlet transform and the gray-scale watermark image is embedded into its
bidiagonal singular values. The proposed method is examined on the images with
different textures and resistance is evaluated against various attacks like
image processing and geometric attacks. The results show good transparency and
high robustness in proposed method.


title: Explaining the geographic origins of seasonal influenza A (H3N2)

abstract:
  Most antigenically novel and evolutionarily successful strains of seasonal
influenza A (H3N2) originate in East, South, and Southeast Asia. To understand
this pattern, we simulated the ecological and evolutionary dynamics of
influenza in a host metapopulation representing the temperate north, tropics,
and temperate south. Although seasonality and air traffic are frequently used
to explain global migratory patterns of influenza, we find that other factors
may have a comparable or greater impact. Notably, a region's basic reproductive
number ($R_0$) strongly affects the antigenic evolution of its viral population
and the probability that its strains will spread and fix globally: a 17-28%
higher $R_0$ in one region can explain the observed patterns. Seasonality, in
contrast, increases the probability that a tropical (less seasonal) population
will export evolutionarily successful strains but alone does not predict that
these strains will be antigenically advanced. The relative sizes of different
host populations, their birth and death rates, and the region in which H3N2
first appears affect influenza's phylogeography in different but relatively
minor ways. These results suggest general principles that dictate the spatial
dynamics of antigenically evolving pathogens and offer predictions for how
changes in human ecology might affect influenza evolution.


title: Fluid Flows of Mixed Regimes in Porous Media

abstract:
  In porous media, there are three known regimes of fluid flows, namely,
pre-Darcy, Darcy and post-Darcy. Because of their different natures, these are
usually treated separately in literature. To study complex flows when all three
regimes may be present in different portions of a same domain, we use a single
equation of motion to unify them. Several scenarios and models are then
considered for slightly compressible fluids. A nonlinear parabolic equation for
the pressure is derived, which is degenerate when the pressure gradient is
either small or large. We estimate the pressure and its gradient for all time
in terms of initial and boundary data. We also obtain their particular bounds
for large time which depend on the asymptotic behavior of the boundary data but
not on the initial one. Moreover, the continuous dependence of the solutions on
initial and boundary data, and the structural stability for the equation are
established.


title:
Force sensing based on coherent quantum noise cancellation in a hybrid
  optomechanical cavity with squeezed-vacuum injection

abstract:
  We propose and analyse a feasible experimental scheme for a quantum force
sensor based on the elimination of back-action noise through coherent quantum
noise cancellation (CQNC) in a hybrid atom-cavity optomechanical setup assisted
with squeezed vacuum injection. The force detector, which allows for a
continuous, broad-band detection of weak forces well below the standard quantum
limit (SQL), is formed by a single optical cavity simultaneously coupled to a
mechanical oscillator and to an ensemble of ultracold atoms. The latter acts as
a negative-mass oscillator so that atomic noise cancels exactly the back-action
noise from the mechanical oscillator due to destructive quantum interference.
Squeezed vacuum injection enforces this cancellation and allows to reach
sub-SQL sensitivity in a very wide frequency band, and at much lower input
laser powers.


title:
Near-Infrared Spectroscopy of the Y0 WISEP J173835.52+273258.9 and the
  Y1 WISE J035000.32-565830.2: the Importance of Non-Equilibrium Chemistry

abstract:
  We present new near-infrared spectra, obtained at Gemini Observatory, for two
Y dwarfs: WISE J035000.32-565830.2 (W0350) and WISEP J173835.52+273258.9
(W1738). A FLAMINGOS-2 R=540 spectrum was obtained for W0350, covering 1.0 <
lambda um < 1.7, and a cross-dispersed GNIRS R=2800 spectrum was obtained for
W1738, covering 0.993-1.087 um, 1.191-1.305 um, 1.589-1.631 um, and 1.985-2.175
um, in four orders. We also present revised YJH photometry for W1738, using new
NIRI Y and J imaging, and a re-analysis of the previously published NIRI H band
images. We compare these data, together with previously published data for
late-T and Y dwarfs, to cloud-free models of solar metallicity, calculated both
in chemical equilibrium and with disequilibrium driven by vertical transport.
We find that for the Y dwarfs the non-equilibrium models reproduce the
near-infrared data better than the equilibrium models. The remaining
discrepancies suggest that fine-tuning the CH_4/CO and NH_3/N_2 balance is
needed. Improved trigonometric parallaxes would improve the analysis. Despite
the uncertainties and discrepancies, the models reproduce the observed
near-infrared spectra well. We find that for the Y0, W1738, T_eff = 425 +/- 25
K and log g = 4.0 +/- 0.25, and for the Y1, W0350, T_eff = 350 +/- 25 K and log
g = 4.0 +/- 0.25. W1738 may be metal-rich. Based on evolutionary models, these
temperatures and gravities correspond to a mass range for both Y dwarfs of 3-9
Jupiter masses, with W0350 being a cooler, slightly older, version of W1738;
the age of W0350 is 0.3-3 Gyr, and the age of W1738 is 0.15-1 Gyr.


title: Some Remarks on Watanabe's Bold Conjecture

abstract:
  At the 2015 Workshop on Lefschetz Properties of Artinian Algebras, Junzo
Watanabe conjectured that every graded Artinian complete intersection algebra
with the standard grading can be embedded into another such algebra cut out by
quadratic generators. We verify this conjecture in the case where the defining
polynomials split into linear factors.


title: Design Rules for High Performance Tunnel Transistors from 2D Materials

abstract:
  Tunneling field-effect transistors (TFETs) based on 2D materials are
promising steep sub-threshold swing (SS) devices due to their tight gate
control. There are two major methods to create the tunnel junction in these 2D
TFETs: electrical and chemical doping. In this work, design guidelines for both
electrically and chemically doped 2D TFETs are provided using full band
atomistic quantum transport simulations in conjunction with analytic modeling.
Moreover, several 2D TFETs' performance boosters such as strain, source doping,
and equivalent oxide thickness (EOT) are studied. Later on, these performance
boosters are analyzed within a novel figure-of-merit plot (i.e. constant
ON-current plot).


title:
Plasmonic Purcell factor and coupling efficiency to surface plasmons.
  Implications for addressing and controlling optical nanosources

abstract:
  The Purcell factor $F_p$ is a key quantity in cavity quantum electrodynamics
(cQED) that quantifies the coupling rate between a dipolar emitter and a cavity
mode. Its simple form $F_p\propto Q/V$ unravels the possible strategies to
enhance and control light-matter interaction. Practically, efficient
light-matter interaction is achieved thanks to either i) high quality factor
$Q$ at the basis of cQED or ii) low modal volume $V$ at the basis of
nanophotonics and plasmonics. In the last decade, strong efforts have been done
to derive a plasmonic Purcell factor in order to transpose cQED concepts to the
nanocale, in a scale-law approach. In this work, we discuss the plasmonic
Purcell factor for both delocalized (SPP) and localized (LSP)
surface-plasmon-polaritons and briefly summarize the expected applications for
nanophotonics. On the basis of the SPP resonance shape (Lorentzian or Fano
profile), we derive closed form expression for the coupling rate to delocalized
plasmons. The quality factor factor and modal confinement of both SPP and LSP
are quantified, demonstrating their strongly subwavelength behaviour.


title: On Primes of Ordinary and Hodge-Witt Reduction

abstract:
  Jean-Pierre Serre has conjectured, in the context of abelian varieties, that
there are infinitely primes of good ordinary reduction for a smooth, projective
variety over a number field. We consider this conjecture and its natural
variants. In particular we have conjectured (with C. S. Rajan) the existence of
infinitely many primes of Hodge-Witt reduction (any prime of ordinary reduction
is also a prime of Hodge-Witt reduction). The two conjectures are not
equivalent but are related. We prove a precise relationship between the two; we
prove several results which provide some evidence for these conjectures; we
show that primes of ordinary and Hodge-Witt reduction can have different
densities. We prove our conjecture on Hodge- Witt and ordinary reduction for
abelian varieties with complex multiplication. We include here an unpublished
joint result with C. S. Rajan (also independently established by Fedor
Bogomolov and Yuri Zarhin by a different method) on the existence of primes of
ordinary reductions for K3 surfaces; our proof also shows that for an abelian
threefold over a number field there is a set of primes of positive density at
which it has Hodge-Witt reduction (this is also a joint result with C. S.
Rajan). We give a number of examples including those of Fermat hypersurfaces
for which all the conjectures we make hold.


title:
Enhancing Sentence Relation Modeling with Auxiliary Character-level
  Embedding

abstract:
  Neural network based approaches for sentence relation modeling automatically
generate hidden matching features from raw sentence pairs. However, the quality
of matching feature representation may not be satisfied due to complex semantic
relations such as entailment or contradiction. To address this challenge, we
propose a new deep neural network architecture that jointly leverage
pre-trained word embedding and auxiliary character embedding to learn sentence
meanings. The two kinds of word sequence representations as inputs into
multi-layer bidirectional LSTM to learn enhanced sentence representation. After
that, we construct matching features followed by another temporal CNN to learn
high-level hidden matching feature representations. Experimental results
demonstrate that our approach consistently outperforms the existing methods on
standard evaluation datasets.


title: Risk contagion under regular variation and asymptotic tail independence

abstract:
  Risk contagion concerns any entity dealing with large scale risks. Suppose
(X,Y) denotes a risk vector pertaining to two components in some system. A
relevant measurement of risk contagion would be to quantify the amount of
influence of high values of Y on X. This can be measured in a variety of ways.
In this paper, we study two such measures: the quantity E[max(X-t,0)|Y > t]
called Marginal Mean Excess (MME) as well as the related quantity E[X|Y > t]
called Marginal Expected Shortfall (MES). Both quantities are indicators of
risk contagion and useful in various applications ranging from finance,
insurance and systemic risk to environmental and climate risk. We work under
the assumptions of multivariate regular variation, hidden regular variation and
asymptotic tail independence for the risk vector (X,Y). Many broad and useful
model classes satisfy these assumptions. We present several examples and derive
the asymptotic behavior of both MME and MES as the threshold t tends to
infinity. We observe that although we assume asymptotic tail independence in
the models, MME and MES converge to 1 under very general conditions; this
reflects that the underlying weak dependence in the model still remains
significant. Besides the consistency of the empirical estimators, we introduce
an extrapolation method based on extreme value theory to estimate both MME and
MES for high thresholds t where little data are available. We show that these
estimators are consistent and illustrate our methodology in both simulated and
real data sets.


title: Ordinary reductions of abelian varieties

abstract:
  I show that a conjecture of Joshi-Rajan on primes of Hodge-Witt reduction and
in particular a conjecture of Jean-Pierre Serre on primes of good, ordinary
reduction for an abelian variety over a number field follows from a certain
conjecture on Galois rep- resentations which may perhaps be easier to prove
(and I prove this conjecture for abelian compatible systems of a suitable
type). This reduction (to a conjecture about certain sys- tems of Galois
representations) is based on a new slope estimate for non Hodge-Witt abelian
varieties. In particular for any abelian variety over a number field with at
least one prime of good ordinary or split toric reduction, I show that the
conjecture of Joshi-Rajan and the conjecture of Serre on ordinary reductions
can be reduced to proving that a certain rational trace of Frobenius is in fact
an integer. The assertion that this trace is an integer is proved for abelian
systems of Galois representations (of suitable type).


title: Dynamical signatures of bound states in waveguide QED

abstract:
  We study the spontaneous decay of an impurity coupled to a linear array of
bosonic cavities forming a single-band photonic waveguide. The average
frequency of the emitted photon is different from the frequency for
single-photon resonant scattering, which perfectly matches the bare frequency
of the excited state of the impurity. We study how the energy of the excited
state of the impurity influences the spatial profile of the emitted photon. The
farther the energy is from the middle of the photonic band, the farther the
wave packet is from the causal limit. In particular, if the energy lies in the
middle of the band, the wave packet is localized around the causal limit.
Besides, the occupation of the excited state of the impurity presents a rich
dynamics: it shows an exponential decay up to intermediate times, this is
followed by a power-law tail in the long-time regime, and it finally reaches an
oscillatory stationary regime. Finally, we show that this phenomenology is
robust under the presence of losses, both in the impurity and the cavities.


title:
Minkowski dimension and explicit tube formulas for $p$-adic fractal
  strings

abstract:
  The local theory of complex dimensions describes the oscillations in the
geometry (spectra and dynamics) of fractal strings. Such geometric oscillations
can be seen most clearly in the explicit volume formula for the tubular
neighborhoods of a $p$-adic fractal string $\mathcal{L}_p$, expressed in terms
of the underlying complex dimensions. The general fractal tube formula obtained
in this paper is illustrated by several examples, including the nonarchimedean
Cantor and Euler strings. Moreover, we show that the Minkowski dimension of a
$p$-adic fractal string coincides with the abscissa of convergence of the
geometric zeta function associated with the string, as well as with the
asymptotic growth rate of the corresponding geometric counting function. The
proof of this new result can be applied to both real and $p$-adic fractal
strings and hence, yields a unifying explanation of a key result in the theory
of complex dimensions for fractal strings, even in the archimedean (or real)
case.


title:
Explicit formulation of second and third order optical nonlinearity in
  the FDTD framework

abstract:
  The finite-difference time-domain (FDTD) method is a flexible and powerful
technique for rigorously solving Maxwell's equations. However,
three-dimensional optical nonlinearity in current commercial and research FDTD
softwares requires solving iteratively an implicit form of Maxwell's equations
over the entire numerical space and at each time step. Reaching numerical
convergence demands significant computational resources and practical
implementation often requires major modifications to the core FDTD engine. In
this paper, we present an explicit method to include second and third order
optical nonlinearity in the FDTD framework based on a nonlinear generalization
of the Lorentz dispersion model. A formal derivation of the nonlinear Lorentz
dispersion equation is equally provided, starting from the quantum mechanical
equations describing nonlinear optics in the two-level approximation. With the
proposed approach, numerical integration of optical nonlinearity and dispersion
in FDTD is intuitive, transparent, and fully explicit. A strong-field
formulation is also proposed, which opens an interesting avenue for FDTD-based
modelling of the extreme nonlinear optics phenomena involved in laser
filamentation and femtosecond micromachining of dielectrics.


title: Gauss-Manin Connection in Disguise: Dwork Family

abstract:
  We study the moduli space $\textsf{T}$ of the Calabi-Yau $n$-folds arising
from the Dwork family and enhanced with bases of the $n$-th de Rham cohomology
with constant cup product and compatible with Hodge filtration. We also
describe a unique vector field $\textsf{R}$ in $\textsf{T}$ which contracted
with the Gauss-Manin connection gives an upper triangular matrix with some
non-constant entries which are natural generalizations of Yukawa couplings. For
$n=1,2$ we compute explicit expressions of $\textsf{R}$ and give a solution of
$\textsf{R}$ in terms of quasi-modular forms. The moduli space $\textsf{T}$ is
an affine variety and for $n=4$ we give explicit coordinate system for
$\textsf{T}$ and compute the vector field $\textsf{R}$ and the $q$-expnasion of
its solution.


title:
A family of Eta Quotients and an Extension of the Ramanujan-Mordell
  Theorem

abstract:
  Let $k\geq 2$ be an integer and $j$ an integer satisfying $1\leq j \leq
4k-5$. We define a family $\{ C_{j,k}(z) \}_{1\leq j \leq 4k-5} $ of eta
quotients, and prove that this family constitute a basis for the space $S_{2k}
(\Gamma_0 (12))$ of cusp forms of weight $2k$ and level $12$. We then use this
basis together with certain properties of modular forms at their cusps to prove
an extension of the Ramanujan-Mordell formula.


title: On varieties with trivial tangent bundle

abstract:
  I prove a crystalline characterization of abelian varieties in characteristic
$p>0$ amongst the class of varieties with trivial tangent bundle. I show using
my characterization that a smooth, projective, ordinary variety with trivial
tangent bundle is an abelian variety if and only if its second crystalline
cohomology is torsion free. I also show that a conjecture of Ke-Zheng Li about
characteristic $p>0$ varieties with trivial tangent bundles is true for
surfaces. I give a new proof of a result of Li and prove a refinement of it.
Based on my characterization of abelian varieties I propose modifications of
Li's conjecture which I expect to be true.


title:
Lattice equations arising from discrete Painlev\'e systems. II.
  $A_4^{(1)}$ case

abstract:
  In this paper, we construct two lattices from the $\tau$ functions of
$A_4^{(1)}$-surface $q$-Painlev\'e equations, on which quad-equations of ABS
type appear. Moreover, using the reduced hypercube structure, we obtain the Lax
pairs of the $A_4^{(1)}$-surface $q$-Painlev\'e equations.