title: The polaron paradigm: a dual coupling effective band model

abstract:
  Non-diagonal couplings to a bosonic bath completely change polaronic
dynamics, from the usual diagonally-coupled paradigm of smoothly-varying
properties. We study, using analytic and numerical methods, a model having both
diagonal Holstein and non-diagonal Su-Schrieffer-Heeger (SSH) couplings. The
critical coupling found previously in the pure SSH model, at which the $k=0$
effective mass diverges, now becomes a transition line in the coupling constant
plane - the form of the line depends on the adiabaticity parameter. Detailed
results are given for the quasiparticle and ground state properties, over a
wide range of couplings and adiabaticity ratios. The new paradigm involves a
destabilization, at the transition line, of the simple Holstein polaron to one
with a finite ground-state momentum, but with everywhere a continuously
evolving band shape. No 'self-trapping transition' exists in any of these
models. The physics may be understood entirely in terms of competition between
different hopping terms in a simple renormalized effective band theory. The
possibility of further transitions is suggested by the results.


title: The Tetrahedral Twists

abstract:
  We introduce a family of piecewise isometries $f_s$ parametrized by $s \in
[0,1)$ on the surface of a regular tetrahedron, which we call the tetrahedral
twists. This family of maps is similar to the PETs constructed by Patrick
Hooper. We study the dynamics of the tetrahedral twists through the notion of
renormalization. By the assistance of computer, we conjecture that the
renormalization scheme exists on the entire interval $[0,1)$. In this paper, we
show that this system is renormalizable in the subintervals
$[\frac{53}{128},\frac{29}{70}]$ and $[\frac{1}{2},1)$.


title:
Towards a general(ized) shear thickening rheology of wet granular
  materials under small pressure

abstract:
  We study the rheology of dry and wet granular materials in the steady
quasistatic regime using the Discrete Element Method (DEM) in a split-bottom
ring shear cell with focus on the macroscopic friction. The aim of our study is
to understand the local rheology of bulk flow at various positions in the shear
band, where the system is in critical state. The general(ized) rheology has
four dimensionless control parameters that relate the time scales of five
significant phenomena, namely, the time scales related to confining pressure
$t_p$, shear rate $t_{\dot{\gamma}}$, particle stiffness $t_k$, gravity $t_g$
and cohesion $t_c$, respectively. We show that those phenomena collectively
contribute to the rheology as multiplicative correction functions.
  While $t_{\dot{\gamma}}$ is large and thus little important for most of the
data studied, it can increase the friction of flow in critical state, where the
shear gradients are high. $t_g$ and $t_k$ are comparable to $t_p$ in the bulk,
but become more or less dominant relative to $t_p$ at the extremes of the free
surface and deep inside the bulk, respectively.
  We also measure the effect of strong wet cohesion on the flow rheology, as
quantified by decreasing $t_c$. Furthermore, the proposed rheological model
predicts well the shear thinning behavior both in the bulk and near the free
surface; shear thinning develops to shear thickening near the free surface with
increasing cohesion.


title:
Stochastic Sampling for Structural Topology Optimization with Many Load
  Cases: Density-Based and Ground Structure Approaches

abstract:
  We propose an efficient probabilistic method to solve a deterministic problem
-- we present a randomized optimization approach that drastically reduces the
enormous computational cost of optimizing designs under many load cases for
both continuum and truss topology optimization. Practical structural designs by
topology optimization typically involve many load cases, possibly hundreds or
more. The optimal design minimizes a, possibly weighted, average of the
compliance under each load case (or some other objective). This means that in
each optimization step a large finite element problem must be solved for each
load case, leading to an enormous computational effort. On the contrary, the
proposed randomized optimization method with stochastic sampling requires the
solution of only a few (e.g., 5 or 6) finite element problems (large linear
systems) per optimization step. Based on simulated annealing, we introduce a
damping scheme for the randomized approach. Through numerical examples in two
and three dimensions, we demonstrate that the stochastic algorithm drastically
reduces computational cost to obtain similar final topologies and results
(e.g., compliance) compared with the standard algorithms. The results indicate
that the damping scheme is effective and leads to rapid convergence of the
proposed algorithm.


title:
Pickup Ion Effect of the Solar Wind Interaction with the Local
  Interstellar Medium

abstract:
  Pickup ions are created when interstellar neutral atoms resonantly exchange
charge with the solar wind (SW) ions, especially in the supersonic part of the
wind, where they carry most of the plasma pressure. Here we present numerical
simulation results of the 3D heliospheric interface treating pickup ions as a
separate proton fluid. To satisfy the fundamental conservation laws, we solve
the system of equations describing the flow of the mixture of electrons,
thermal protons, and pickup ions. To find the density and pressure of pickup
ions behind the termination shock, we employ simple boundary conditions that
take into account the \emph{Voyager} observations that showed that the decrease
in the kinetic energy of the mixture at the termination shock predominantly
contributed to the increase in the pressure of pickup ions. We show that this
model adequately describes the flow of the plasma mixture and results in a
noticeable decrease in the heliosheath width.


title: Hamilton cycles in hypergraphs below the Dirac threshold

abstract:
  We establish a precise characterisation of $4$-uniform hypergraphs with
minimum codegree close to $n/2$ which contain a Hamilton $2$-cycle. As an
immediate corollary we identify the exact Dirac threshold for Hamilton
$2$-cycles in $4$-uniform hypergraphs. Moreover, by derandomising the proof of
our characterisation we provide a polynomial-time algorithm which, given a
$4$-uniform hypergraph $H$ with minimum codegree close to $n/2$, either finds a
Hamilton $2$-cycle in $H$ or provides a certificate that no such cycle exists.
This surprising result stands in contrast to the graph setting, in which below
the Dirac threshold it is NP-hard to determine if a graph is Hamiltonian. We
also consider tight Hamilton cycles in $k$-uniform hypergraphs $H$ for $k \geq
3$, giving a series of reductions to show that it is NP-hard to determine
whether a $k$-uniform hypergraph $H$ with minimum degree $\delta(H) \geq
\frac{1}{2}|V(H)| - O(1)$ contains a tight Hamilton cycle. It is therefore
unlikely that a similar characterisation can be obtained for tight Hamilton
cycles.


title:
Numerical Solution of a Coefficient Inverse Problem with Multi-Frequency
  Experimental Raw Data by a Globally Convergent Algorithm

abstract:
  We analyze in this paper the performance of a newly developed globally
convergent numerical method for a coefficient inverse problem for the case of
multi-frequency experimental backscatter data associated to a single incident
wave. These data were collected using a microwave scattering facility at the
University of North Carolina at Charlotte. The challenges for the inverse
problem under the consideration are not only from its high nonlinearity and
severe ill-posedness but also from the facts that the amount of the measured
data is minimal and that these raw data are contaminated by a significant
amount of noise, due to a non-ideal experimental setup. This setup is motivated
by our target application in detecting and identifying explosives. We show in
this paper how the raw data can be preprocessed and successfully inverted using
our inversion method. More precisely, we are able to reconstruct the dielectric
constants and the locations of the scattering objects with a good accuracy,
without using any advanced \emph{a priori} knowledge of their physical and
geometrical properties.


title: Uncertainty in Monotone Co-Design Problems

abstract:
  This work contributes to a compositional theory of "co-design" that allows to
optimally design a robotic platform. In this framework, the user describes each
subsystem as a monotone relation between "functionality" provided and
"resources" required. These models can be easily composed to express the
co-design constraints among different subsystems. The user then queries the
model, to obtain the design with minimal resources usage, subject to a lower
bound on the provided functionality. This paper concerns the introduction of
uncertainty in the framework. Uncertainty has two roles: first, it allows to
deal with limited knowledge of the models; second, it also can be used to
generate consistent relaxations of a problem, as the computation requirements
can be lowered, should the user accept some uncertainty in the answer.


title: Strongly coupled non-Abelian plasmas in a magnetic field

abstract:
  In this dissertation we use the gauge/gravity duality approach to study the
dynamics of strongly coupled non-Abelian plasmas. Ultimately, we want to
understand the properties of the quark-gluon plasma (QGP), whose scientifc
interest by the scientific community escalated exponentially after its
discovery in the 2000's through the collision of ultrarelativistic heavy ions.
  One can enrich the dynamics of the QGP by adding an external field, such as
the baryon chemical potential (needed to study the QCD phase diagram), or a
magnetic field. In this dissertation, we choose to investigate the magnetic
effects. Indeed, there are compelling evidences that strong magnetic fields of
the order $eB\sim 10 m_\pi^2$ are created in the early stages of
ultrarelativistic heavy ion collisions.
  The chosen observable to scan possible effects of the magnetic field on the
QGP was the viscosity, due to the famous result $\eta/s=1/4\pi$ obtained via
holography. In a first approach we use a caricature of the QGP, the
$\mathcal{N}=4$ super Yang-Mills plasma to calculate the deviations of the
viscosity as we add a magnetic field. We must emphasize, though, that a
magnetized plasma has a priori seven viscosity coefficients (five shears and
two bulks). In addition, we also study in this same model the anisotropic heavy
quark-antiquark potential in the presence of a magnetic field.
  In the end, we propose a phenomenological holographic QCD-like model, which
is built upon the lattice QCD data, to study the thermodynamics and the
viscosity of the QGP with an external strong magnetic field.


title: Large Sets Avoiding Patterns

abstract:
  We construct subsets of Euclidean space of large Hausdorff dimension and full
Minkowski dimension that do not contain nontrivial patterns described by the
zero sets of functions. The results are of two types. Given a countable
collection of $v$-variate vector-valued functions $f_q : (\mathbb{R}^{n})^v \to
\mathbb{R}^m$ satisfying a mild regularity condition, we obtain a subset of
$\mathbb{R}^n$ of Hausdorff dimension $\frac{m}{v-1}$ that avoids the zeros of
$f_q$ for every $q$. We also find a set that simultaneously avoids the zero
sets of a family of uncountably many functions sharing the same linearization.
In contrast with previous work, our construction allows for non-polynomial
functions as well as uncountably many patterns. In addition, it highlights the
dimensional dependence of the avoiding set on $v$, the number of input
variables.


title: On Some Universally Good Fractional Repetition Codes

abstract:
  Data storage in Distributed Storage Systems (DSSs) is a multidimensional
optimization problem. Using network coding, one wants to provide reliability,
scalability, security, reduced storage overhead, reduced bandwidth for repair
and minimal disk I/O etc. in such systems. Regenerating codes have been used to
optimize some of these parameters, where a file can be reconstructed by
contacting any k nodes in the system and in case of node failure it can be
repaired by using any d nodes in the system. This was further generalized to
Fractional repetition (FR) codes (a smart replication of encoded packets) on n
nodes which also provides optimized disk I/O and where a node failure can be
repaired by contacting some specific set of nodes in the system. Several
constructions of FR codes using graphs and combinatorial designs are known. In
particular, some constructions of codes for heterogeneous DSSs are given using
partial regular graph (where number of packets on each node is different) and
ring construction. In this work, we show that the codes constructed using the
partial regular graph are universally good code. Further, we found several
universally good codes using ring construction and t-construction.


title: Large Deviations for Brownian Particle Systems with Killing

abstract:
  Particle approximations for certain nonlinear and nonlocal reaction-diffusion
equations are studied using a system of Brownian motions with killing. The
system is described by a collection of i.i.d. Brownian particles where each
particle is killed independently at a rate determined by the empirical
sub-probability measure of the states of the particles alive. A large deviation
principle (LDP) for such sub-probability measure-valued processes is
established. Along the way a convenient variational representation, which is of
independent interest, for expectations of nonnegative functionals of Brownian
motions together with an i.i.d. sequence of random variables is established.
Proof of the LDP relies on this variational representation and weak convergence
arguments.


title: Assembly Sequence Planning for Motion Planning

abstract:
  This paper develops a planner to find an optimal assembly sequence to
assemble several objects. The input to the planner is the mesh models of the
objects, the relative poses between the objects in the assembly, and the final
pose of the assembly. The output is an optimal assembly sequence, namely (1) in
which order should one assemble the objects, (2) from which directions should
the objects be dropped, and (3) candidate grasps of each object. The proposed
planner finds the optimal solution by automatically permuting, evaluating, and
searching the possible assembly sequences considering stability, graspability,
and assemblability qualities. It is expected to guide robots to do assembly
using translational motion. The output provides initial and goal configurations
to motion planning algorithms. It is ready to be used by robots and is
demonstrated using several simulations and real-world executions.


title:
Message Authentication and Secret Key Agreement in VANETs via Angle of
  Arrival

abstract:
  In the scope of VANETs, nature of exchanged safety/warning messages renders
itself highly location dependent as it is usually for incident reporting. Thus,
vehicles are required to periodically exchange beacon messages that include
speed, time and GPS location information. In this paper paper, we present a
physical layer assisted message authentication scheme that uses Angle of
Arrival (AoA) estimation to verify the message originator location based on the
claimed location information. Within the considered vehicular communication
settings, fundamental limits of AoA estimation are developed in terms of its
Cramer Rao Bound (CRB) and existence of efficient estimator. The problem of
deciding whether the received signal is originated from the claimed GPS
location is formulated as a two sided hypotheses testing problem whose solution
is given by Wald test statics. Moreover, we use correct decision, $P_D$, and
false alarm, $P_F$, probabilities as a quantitative performance measure. The
observation posterior likelihood function is shown to satisfy regularity
conditions necessary for asymptotic normality of the ML-AoA estimator. Thus, we
give $P_D$ and $P_F$ in a closed form.
  We extend the potential of physical layer contribution in security to provide
physical layer assisted secret key agreement (SKA) protocol. A public key (PK)
based SKA in which communicating vehicles are required to validate their
respective physical location. We show that the risk of the Man in the Middle
attack, which is common in PK-SKA protocols without a trusted third party, is
waived up to the literal meaning of the word "middle".


title: Directed graphs and its Boundary Vertices

abstract:
  Suppose that $D=(V,E)$ is a strongly connected digraph. Let $u,v\in V(D)$.
The maximum distance $md (u,v)$ is defined as
$md(u,v)$=max\{$\overrightarrow{d}(u,v), \overrightarrow{d}(v,u)$\} where
$\overrightarrow{d}(u,v)$ denote the length of a shortest directed $u-v$ path
in $D$. This is a metric. The boundary, contour, eccentric and peripheral sets
of a strong digraph $D$ are defined with respect to this metric. The main aim
of this paper is to identify the above said metrically defined sets of a large
strong digraph $D$ in terms of its prime factor decomposition with respect to
cartesian product.


title:
Expansion formula for complex Monge-Amp\`ere equation along cone
  singularities

abstract:
  In this paper, we prove the asymptotic expansion of the solutions to some
singular complex Monge-Amp\`ere equation which arise naturally in the study of
the conical K\"ahler-Einstein metric.


title:
Photochemistry and astrochemistry: photochemical pathways to
  interstellar complex organic molecules

abstract:
  The interstellar medium is characterized by a rich and diverse chemistry.
Many of its complex organic molecules are proposed to form through radical
chemistry in icy grain mantles. Radicals form readily when interstellar ices
(composed of water and other volatiles) are exposed to UV photons and other
sources of dissociative radiation, and, if sufficiently mobile, the radicals
can react to form larger, more complex molecules. The resulting complex organic
molecules (COMs) accompany star and planet formation, and may eventually seed
the origins of life on nascent planets. Experiments of increasing
sophistication have demonstrated that known interstellar COMs as well as the
prebiotically interesting amino acids can form through ice photochemistry. We
review these experiments and discuss the qualitative and quantitative kinetic
and mechanistic constraints they have provided. We finally compare the effects
of UV radiation with those of three other potential sources of radical
production and chemistry in interstellar ices: electrons, ions and X-rays.


title:
Ultrafast coherent control of spinor Bose-Einstein condensates using
  stimulated Raman adiabatic passage

abstract:
  We propose the use of stimulated Raman adiabatic passage (STIRAP) to offer a
fast high fidelity method of performing SU(2) rotations on spinor Bose Einstein
condensates (BEC). Past demonstrations of BEC optical control suffer from
difficulties arising from collective enhancement of spontaneous emission and
inefficient two-photon transitions originating from selection rules. We present
here a novel scheme which allows for arbitrary coherent rotations of
two-component BECs while overcoming these issues. Numerical tests of the method
show that for BECs of \ce{^{87}Rb} with up to $ 10^4 $ atoms and gate times of
$ \SI{1}{\micro\second} $, decoherence due to spontaneous emission can be
suppressed to negligible values.


title:
Angular dependence of electron spin resonance for detecting quadrupolar
  liquid state of frustrated spin chains

abstract:
  Spin nematic phase is a phase of frustrated quantum magnets with a
quadrupolar order of electron spins. Since the spin nematic order is usually
masked in experimentally accessible quantities, it is important to develop a
methodology for detecting the spin nematic order experimentally. In this paper
we propose a convenient method for detecting quasi-long-range spin nematic
correlations of a quadrupolar Tomonaga-Luttinger liquid state of $S=1/2$
frustrated ferromagnetic spin chain compounds, using electron spin resonance
(ESR). We focus on linewidth of a so-called paramagnetic resonance peak in ESR
absorption spectrum. We show that a characteristic angular dependence of the
linewidth on the direction of magnetic field arises in the spin nematic phase.
Measurments of the angular dependence give a signature of the quadrupolar
Tomonaga-Luttinger liquid state. In our method we change only the direction of
the magnetic field, keeping the magnitude of the magnetic field and the
temperature. Therefore, our method is advantageous for investigating the
one-dimensional quadrupolar liquid phase that usually occupies only a narrow
region of the phase diagram.


title: Regular Policies in Abstract Dynamic Programming

abstract:
  We consider challenging dynamic programming models where the associated
Bellman equation, and the value and policy iteration algorithms commonly
exhibit complex and even pathological behavior. Our analysis is based on the
new notion of regular policies. These are policies that are well-behaved with
respect to value and policy iteration, and are patterned after proper policies,
which are central in the theory of stochastic shortest path problems. We show
that the optimal cost function over regular policies may have favorable value
and policy iteration properties, which the optimal cost function over all
policies need not have. We accordingly develop a unifying methodology to
address long standing analytical and algorithmic issues in broad classes of
undiscounted models, including stochastic and minimax shortest path problems,
as well as positive cost, negative cost, risk-sensitive, and multiplicative
cost problems.


title:
Enumeration of Hybrid Domino-Lozenge Tilings III: Centrally Symmetric
  Tilings

abstract:
  We use the subgraph replacement method to investigate new properties of the
tilings of regions on the square lattice with diagonals drawn in. In
particular, we show that the centrally symmetric tilings of a generalization of
the Aztec diamond are always enumerated by a simple product formula. This
result generalizes the previous work of Ciucu (1997) and Yang (1992) about
symmetric tilings of the Aztec diamond. We also use our method to prove a
closed-form product formula for the number of centrally symmetric tilings of a
quasi-hexagon.


title:
On the Power-Law Distributions of X-ray Fluxes from Solar Flares
  Observed with GOES

abstract:
  Power-law frequency distributions of the peak flux of solar flare X-ray
emission have been studied extensively and attributed to a system of
self-organized criticality (SOC). In this paper, we first show that, so long as
the shape of the normalized light curve is not correlated with the peak flux,
the flux histogram of solar flares also follows a power-law distribution with
the same spectral index as the power-law frequency distribution of the peak
flux, which may partially explain why power-law distributions are ubiquitous in
the Universe. We then show that the spectral indexes of the histograms of soft
X-ray fluxes observed by GOES satellites in two different energy channels are
different: the higher energy channel has a harder distribution than the lower
energy channel, which challenges the universal power-law distribution predicted
by SOC models and implies a very soft distribution of thermal energy content of
plasmas probed by the GOES. The temperature ($T$) distribution, on the other
hand, approaches a power-law distribution with an index of 2 for high values of
$T$. Application of SOC models to statistical properties of solar flares needs
to be revisited.


abstract:
  Neutrino potential for neutrinoless double beta decay is studied with
focusing on its statistical property. The statistics provide a gross view of
understanding amplitude of constitutional components of the nuclear matrix
element.


title: Three open problems on the Wijsman topology

abstract:
  Since it first emerged in Wijsman's seminal work [29], the Wijsman topology
has been intensively studied in the past 50 years. In particular, topological
properties of Wijsman hyperspaces, relationships between the Wijsman topology
and other hyperspace topologies, and applications of the Wijsman topology in
analysis have been explored. However, there are still several fundamental open
problems on this topology. In this article, the author gives a brief survey on
these problems and some up-to-date partial solutions.


title: Random Matrix Ensembles with Split Limiting Behavior

abstract:
  We introduce a new family of $N\times N$ random real symmetric matrix
ensembles, the $k$-checkerboard matrices, whose limiting spectral measure has
two components which can be determined explicitly. All but $k$ eigenvalues are
in the bulk, and their behavior, appropriately normalized, converges to the
semi-circle as $N\to\infty$; the remaining $k$ are tightly constrained near
$N/k$ and their distribution converges to the $k \times k$ hollow GOE ensemble
(this is the density arising by modifying the GOE ensemble by forcing all
entries on the main diagonal to be zero). Similar results hold for complex and
quaternionic analogues. We isolate the two regimes by using matrix perturbation
results and a nonstandard weight function for the eigenvalues, then derive
their limiting distributions using a modification of the method of moments and
analysis of the resulting combinatorics.


title:
Pseudospin 3/2 Fermions, Type-II Weyl Semimetals and Critical Weyl
  Semimetals in Tricolor Cubic Lattice

abstract:
  Multi-band touchings such as 3-band, 6-band and 8-band touchings together
with the emergence of high pseudospin fermions were predicted recently at
high-symmetry points in three-dimensional space. In this paper, we propose a
simple cubic model whose unit cell contains three atoms. There are 6 bands in
the system due to the spin degrees of freedom. The 4-band and 2-band touchings
are realized at high-symmetry points, where we derive low-energy theories,
demonstrating the emergence of pseudospin-3/2 fermions and Weyl fermions,
respectively. Away from the high-symmetry points, we find critical Weyl
fermions present exactly at the boundary between the type-I and type-II Weyl
fermions. This critical Weyl fermion transforms into the type-I or type-II Weyl
fermion once the magnetic field is applied.


title: Color groups of colorings of $N$-planar modules

abstract:
  A submodule of a $\mathbb{Z}$-module determines a coloring of the module
where each coset of the submodule is associated to a unique color. Given a
submodule coloring of a $\mathbb{Z}$-module, the group formed by the symmetries
of the module that induces a permutation of colors is referred to as the color
group of the coloring. In this contribution, a method to solve for the color
groups of colorings of $N$-planar modules where $N=4$ and $N=6$ are given.
Examples of colorings of rectangular lattices and of the vertices of the
Ammann-Beenker tiling are given to exhibit how these methods may be extended to
the general case.


title: A local order metric for condensed phase environments

abstract:
  We introduce a local order metric (LOM) that measures the degree of order in
the neighborhood of an atomic or molecular site in a condensed medium. The LOM
maximizes the overlap between the spatial distribution of sites belonging to
that neighborhood and the corresponding distribution in a suitable reference
system. The LOM takes a value tending to zero for completely disordered
environments and tending to one for environments that match perfectly the
reference. The site averaged LOM and its standard deviation define two scalar
order parameters, $S$ and $\delta S$, that characterize with excellent
resolution crystals, liquids, and amorphous materials. We show with molecular
dynamics simulations that $S$, $\delta S$ and the LOM provide very insightful
information in the study of structural transformations, such as those occurring
when ice spontaneously nucleates from supercooled water or when a supercooled
water sample becomes amorphous upon progressive cooling.

categories: physics.comp-ph cond-mat.mtrl-sci physics.atm-clus physics.chem-ph


title: Search for Higgs-like bosons decaying into long-lived exotic particles

abstract:
  A search is presented for massive long-lived particles, in the 20-60 GeV mass
range with lifetimes between 5 and 100 ps. The dataset used corresponds to 0.62
1\fb of proton-proton collision data collected by the LHCb detector at
sqrt(s)=7 TeV. The particles are assumed to be pair-produced by the decay of a
Higgs-like boson with mass between 80 and 140 GeV. No excess above the
background expectation is observed and limits are set on the production
cross-section as a function of the long-lived particle mass and lifetime and of
the Higgs-like boson mass.


title: An invariant K\"ahler metric on the tangent disk bundle of a space-form

abstract:
  We find a family of K\"ahler metrics invariantly defined on the radius
$r_0>0$ tangent disk bundle ${{\cal T}_{M,r_0}}$ of any given real space-form
$M$ or any of its quotients by discrete groups of isometries. Such metrics are
complete in the non-negative curvature case and non-complete in the negative
curvature case. If $\dim M=2$ and $M$ has constant sectional curvature
$K\neq0$, then the K\"ahler manifolds ${{\cal T}_{M,r_0}}$ have holonomy
$\mathrm{SU}(2)$; hence they are Ricci-flat. For $M=S^2$, just this dimension,
the metric coincides with the Stenzel metric on the tangent manifold ${{\cal
T}_{S^2}}$, giving us a new most natural description of this well-know metric.


abstract:
  We introduce the "Energy-based Generative Adversarial Network" model (EBGAN)
which views the discriminator as an energy function that attributes low
energies to the regions near the data manifold and higher energies to other
regions. Similar to the probabilistic GANs, a generator is seen as being
trained to produce contrastive samples with minimal energies, while the
discriminator is trained to assign high energies to these generated samples.
Viewing the discriminator as an energy function allows to use a wide variety of
architectures and loss functionals in addition to the usual binary classifier
with logistic output. Among them, we show one instantiation of EBGAN framework
as using an auto-encoder architecture, with the energy being the reconstruction
error, in place of the discriminator. We show that this form of EBGAN exhibits
more stable behavior than regular GANs during training. We also show that a
single-scale architecture can be trained to generate high-resolution images.


title:
Unbiased `walk-on-spheres' Monte Carlo methods for the fractional
  Laplacian

abstract:
  We consider Monte Carlo methods for simulating solutions to the analogue of
the Dirichlet boundary-value problem in which the Laplacian is replaced by the
fractional Laplacian and boundary conditions are replaced by conditions on the
exterior of the domain. Specifically, we consider the analogue of the so-called
`walk-on-spheres` algorithm. In the diffusive setting, this entails sampling
the path of Brownian motion as it uniformly exits a sequence of spheres
maximally inscribed in the domain. As this algorithm would otherwise never end,
it is truncated when the `walk-on-spheres` comes within epsilon > 0 of the
boundary. In the setting of the fractional Laplacian, the role of Brownian
motion is replaced by an isotropic alpha-stable process with alpha in (0, 2). A
significant difference to the Brownian setting is that the stable processes
will exit spheres by a jump rather than hitting their boundary. This difference
ensures that disconnected domains may be considered and that, unlike the
diffusive setting, the algorithm ends after an almost surely finite number of
steps.


title: On parking functions and the zeta map in types B,C and D

abstract:
  Let $\Phi$ be an irreducible crystallographic root system with Weyl group
$W$, coroot lattice $\check{Q}$ and Coxeter number $h$. Recently the second
named author defined a uniform $W$-isomorphism $\zeta$ between the finite torus
$\check{Q}/(mh+1)\check{Q}$ and the set of non-nesting parking fuctions
$\operatorname{Park}^{(m)}(\Phi)$. If $\Phi$ is of type $A_{n-1}$ and $m=1$
this map is equivalent to a map defined on labelled Dyck paths that arises in
the study of the Hilbert series of the space of diagonal harmonics.
  In this paper we investigate the case $m=1$ for the other infinite families
of root systems ($B_n$, $C_n$ and $D_n$). In each type we define models for the
finite torus and for the set of non-nesting parking functions in terms of
labelled lattice paths. The map $\zeta$ can then be viewed as a map between
these combinatorial objects. Our work entails new bijections between (square)
lattice paths and ballot paths.


title: Bulging brains

abstract:
  Brain swelling is a serious condition associated with an accumulation of
fluid inside the brain that can be caused by trauma, stroke, infection, or
tumors. It increases the pressure inside the skull and reduces blood and oxygen
supply. To relieve the intracranial pressure, neurosurgeons remove part of the
skull and allow the swollen brain to bulge outward, a procedure known as
decompressive craniectomy. Decompressive craniectomy has been preformed for
more than a century; yet, its effects on the swollen brain remain poorly
understood. Here we characterize the deformation, strain, and stretch in
bulging brains using the nonlinear field theories of mechanics. Our study shows
that even small swelling volumes of 28 to 56 ml induce maximum principal
strains in excess of 30%. For radially outward-pointing axons, we observe
maximal normal stretches of 1.3 deep inside the bulge and maximal tangential
stretches of 1.3 around the craniectomy edge. While the stretch magnitude
varies with opening site and swelling region, our study suggests that the
locations of maximum stretch are universally shared amongst all bulging brains.
Our model can inform neurosurgeons and rationalize the shape and position of
the skull opening, with the overall goal to reduce brain damage and improve the
structural and functional outcomes of decompressive craniectomy in trauma
patients.


title:
Gaussian Processes Online Observation Classification for RSSI-based
  Low-cost Indoor Positioning Systems

abstract:
  In this paper, we propose a real-time classification scheme to cope with
noisy Radio Signal Strength Indicator (RSSI) measurements utilized in indoor
positioning systems. RSSI values are often converted to distances for position
estimation. However due to multipathing and shadowing effects, finding a unique
sensor model using both parametric and non-parametric methods is highly
challenging. We learn decision regions using the Gaussian Processes
classification to accept measurements that are consistent with the operating
sensor model. The proposed approach can perform online, does not rely on a
particular sensor model or parameters, and is robust to sensor failures. The
experimental results achieved using hardware show that available positioning
algorithms can benefit from incorporating the classifier into their measurement
model as a meta-sensor modeling technique.


title:
Orbital dynamics of a solar sail accelerated by thermal desorption of
  coatings

abstract:
  In this study we considered a solar sail coated with materials that undergo
thermal desorption at a specific temperature, as a result of heating by solar
radiation at a particular heliocentric distance. Three different scenarios,
that only differ in the way the sail approaches the Sun, were analyzed and
compared. In every case once the perihelion is reached, the sail coat undergoes
thermal desorption. When the desorption process ends, the sail then escapes the
Solar System having the conventional acceleration due to solar radiation
pressure. Thermal desorption here comes as an additional source of solar sail
acceleration beside traditional propulsion systems for extrasolar space
exploration. The compared scenarios are the following: i. Hohmann transfer plus
thermal desorption. In this scenario the sail would be carried as a payload to
the perihelion with a conventional propulsion system by an Hohmann transfer
from Earth's orbit to an orbit very close to the Sun (almost at 0.1 AU) and
then be deployed there. ii. Elliptical transfer plus Slingshot plus thermal
desorption. In this scenario the transfer occurs from Earth's orbit to
Jupiter's orbit. A Jupiter's fly-by leads to the orbit close to the Sun, where
the sail is deployed. iii. Two stage acceleration of the solar sail through
thermal desorption. The proposed sail has two coats of the materials that
undergo thermal desorption at different temperatures depending on the
heliocentric distance. The first desorption occurs at the Earth orbit and
provides the thrust needed to propel the solar sail toward the Sun. The second
desorption is equivalent to that of the other scenarios.


title: Rough path metrics on a Besov--Nikolskii type scale

abstract:
  It is known, since the seminal work [T. Lyons, Differential equations driven
by rough signals, Rev. Mat. Iberoamericana, 14 (1998)], that the solution map
associated to a controlled differential equation is locally Lipschitz
continuous in $q$-variation resp. $1/q$-H\"{o}lder type metrics on the space of
rough paths, for any regularity $1/q \in (0,1]$. We extend this to a new class
of Besov-Nikolskii-type metrics, with arbitrary regularity $1/q\in (0,1]$ and
integrability $p\in [ q,\infty ]$, where the case $p\in \{ q,\infty \} $
corresponds to the known cases. Interestingly, the result is obtained as
consequence of known $q$-variation rough path estimates.


title: When almost Cohen-Macaulay algebras map into big Cohen-Macaulay modules

abstract:
  In this paper, we show that almost Cohen-Macaulay algebras are solid and in
this respect, we seek for some special situation when (a) an almost
Cohen-Macaulay algebra will be phantom extension and (b) when it maps into a
balanced big Cohen-Macaulay module.


title: Construction of Arakelov-modular Lattices from Number Fields

abstract:
  An Arakelov-modular lattice of level $\ell$, where $\ell$ is a positive
integer, is an $\ell-$modular lattice constructed from a fractional ideal of a
CM field such that the lattice can be obtained from its dual by multiplication
of an element with norm $\ell$. The characterization of existence of
Arakelov-modular lattices has been completed for cyclotomic fields [4]. In this
paper, we extend the definition to totally real number fields and study the
criteria for the existence of Arakelov-modular lattices over totally real
number fields and CM fields. We give the characterization of Arakelov-modular
lattices over the maximal real subfield of a cyclotomic field with prime power
degree and totally real Galois fields with odd degrees. Characterizations of
Arakelov-modular lattices of trace type, which are special cases of
Arakelov-modular lattices, are given for quadratic fields and maximal real
subfields of cyclotomic fields with non-prime power degrees.


title: Accretion at the periastron passage of Eta Carinae

abstract:
  We present high resolution numerical simulations of the colliding wind system
$\eta$ Carinae, showing accretion onto the secondary star close to periastron
passage. Our hydrodynamical simulations include self gravity and radiative
cooling. The smooth stellar winds collide and develop instabilities, mainly the
non-linear thin shell instability, and form filaments and clumps. We find that
a few days before periastron passage the dense filaments and clumps flow
towards the secondary as a result of its gravitational attraction, and reach
the zone where we inject the secondary wind. We run our simulations for the
conventional stellar masses, $M_1=120 ~\rm{M_\odot}$ and $M_2=30
~\rm{M_\odot}$, and for a high mass model, $M_1=170 ~\rm{M_\odot}$ and $M_2=80
~\rm{M_\odot}$, that was proposed to better fit the history of giant eruptions.
As expected, the simulations results show that the accretion processes is more
pronounced for a more massive secondary star.


title:
A Heuristic Method of Generating Diameter 3 Graphs for Order/Degree
  Problem

abstract:
  We propose a heuristic method that generates a graph for order/degree
problem. Target graphs of our heuristics have large order (> 4000) and diameter
3. We describe the ob- servation of smaller graphs and basic structure of our
heuristics. We also explain an evaluation function of each edge for efficient
2-opt local search. Using them, we found the best solutions for several graphs.


title:
On a general framework for network representability in discrete
  optimization

abstract:
  In discrete optimization, representing an objective function as an $s$-$t$
cut function of a network is a basic technique to design an efficient
minimization algorithm. A network representable function can be minimized by
computing a minimum $s$-$t$ cut of a directed network, which is a very easy and
fastly solved problem. Hence it is natural to ask what functions are network
representable. In the case of pseudo Boolean functions (functions on
$\{0,1\}^n$), it is known that any submodular function on $\{0,1\}^3$ is
network representable. \v{Z}ivn\'y--Cohen--Jeavons showed by using the theory
of expressive power that a certain submodular function on $\{0,1\}^4$ is not
network representable.
  In this paper, we introduce a general framework for the network
representability of functions on $D^n$, where $D$ is an arbitrary finite set.
We completely characterize network representable functions on $\{0,1\}^n$ in
our new definition. We can apply the expressive power theory to the network
representability in the proposed definition. We prove that some ternary
bisubmodular function and some binary $k$-submodular function are not network
representable.


title: Bent functions and line ovals

abstract:
  In this paper we study those bent functions which are linear on elements of
spreads, their connections with ovals and line ovals, and we give descriptions
of their dual bent functions. In particular, we give a geometric
characterization of Niho bent functions and of their duals, we give explicit
formula for the dual bent function and present direct connections with ovals
and line ovals. We also show that bent functions which are linear on elements
of inequivalent spreads can be EA-equivalent.


title:
A Short Mechanized Proof of the Church-Rosser Theorem by the Z-property
  for the $\lambda\beta$-calculus in Nominal Isabelle

abstract:
  We present a short proof of the Church-Rosser property for the
lambda-calculus enjoying two distinguishing features: Firstly, it employs the
Z-property, resulting in a short and elegant proof; and secondly, it is
formalized in the nominal higher-order logic available for the proof assistant
Isabelle/HOL.


title: Learning Semantic Part-Based Models from Google Images

abstract:
  We propose a technique to train semantic part-based models of object classes
from Google Images. Our models encompass the appearance of parts and their
spatial arrangement on the object, specific to each viewpoint. We learn these
rich models by collecting training instances for both parts and objects, and
automatically connecting the two levels. Our framework works incrementally, by
learning from easy examples first, and then gradually adapting to harder ones.
A key benefit of this approach is that it requires no manual part location
annotations. We evaluate our models on the challenging PASCAL-Part dataset [1]
and show how their performance increases at every step of the learning, with
the final models more than doubling the performance of directly training from
images retrieved by querying for part names (from 12.9 to 27.2 AP). Moreover,
we show that our part models can help object detection performance by enriching
the R-CNN detector with parts.


title: Spin-Orbit Coupling Induced Spin Squeezing in Three-Component Bose Gases

abstract:
  We observe spin squeezing in three-component Bose gases where all three
hyperfine states are coupled by synthetic spin-orbit coupling. This phenomenon
is a direct consequence of spin-orbit coupling, as can be seen clearly from an
effective spin Hamiltonian. By solving this effective model analytically with
the aid of a Holstein-Primakoff transformation for spin-1 system in the low
excitation limit, we conclude that the spin-nematic squeezing, a novel category
of spin squeezing existing exclusively in large spin systems, is enhanced with
increasing spin-orbit intensity and effective Zeeman field, which correspond to
Rabi frequency and two-photon detuning within the Raman scheme for synthetic
spin-orbit coupling, respectively. These trends of dependence are in clear
contrast to spin-orbit coupling induced spin squeezing in spin-1/2 systems. We
also analyze the effects of harmonic trap and interaction with realistic
experimental parameters numerically, and find that a strong harmonic trap
favors spin-nematic squeezing. We further show spin-nematic squeezing can be
interpreted as two-mode entanglement or two-spin squeezing at low excitation.
Our findings can be observed in ^{87}Rb gases with existing techniques of
synthetic spin-orbit coupling and spin-selectively imaging.


title:
Exact Dimensionality Reduction for Partial Line Spectra Estimation
  Problems

abstract:
  Line spectral estimation theory aims to estimate the off-the-grid spectral
components of a time signal with optimal precision. Recent results have shown
that it is possible to recover signals having sparse line spectra from few
temporal observations via the use of convex programming. However, the
computational cost of such approaches remains the major flaw to their
application to practical systems. This work investigates the recovery of
spectrally sparse signal from low-dimensional partial measurements. It is shown
in the first part of this paper that, under a light assumption on the
sub-sampling matrix, the partial line spectral estimation problems can be
relaxed into a low-dimensional semidefinite program. The proof technique relies
on a novel extension of the Gram parametrization to subspaces of trigonometric
polynomials.
  The second part of this work focuses on the analysis of two particular
sub-sampling patterns: multirate sampling and random selection sampling. It is
shown that those sampling patterns guarantee perfect recovery of the line
spectra, and that the reconstruction can be achieved in a poly-logarithmic time
with respect to the full observation case. Moreover, the sub-Nyquist recovery
capabilities of such sampling patterns are highlighted. The atomic soft
thresholding method is adapted in the presented framework to estimate sparse
spectra in noisy environments, and a scalable algorithm for its resolution is
proposed.


title: Spherical classes in some finite loop spaces of spheres

abstract:
  Working at the prime $2$, Curtis conjecture predicts that, in positive
dimensions, spherical classes in $H_*QS^0$ only arise from Hopf invariant one
and Kervaire invariant one elements. Eccles conjecture states that, in positive
dimensional, for a path connected space $X$, a class in $H_nQX$ is spherical if
its either stably spherical or it arises from a stable map $S^n\to X$ which is
detected by a primary operation in its mapping cone. (i) We use Hopf invariant
one result to verify Eccles conjecture on some finite loop spaces of spheres,
namely, for $X=S^k$ , we completely determine spherical classes in
$H_*(\Omega^dS^{k+d};\mathbb{Z}/2)$ for specific values of $d$, $k$ showing
that a spherical classes in these cases only do arise from Hopf invariant one
elements. (ii) We completely determine spherical classes in homology of single,
double, and triple loop spaces of spheres, namely $\Omega S^{n+1}$, $\Omega^2
S^{n+2}$, and $\Omega^3S^{n+3}$ with $n>0$. These computations, verify Eccles
conjecture on the finite loop spaces that we have considered. We also record
some observations on the relation between two conjectures. The latter
conjecture for $X=S^k$, with $k>0$, provides some evidence for the former to be
true.


title:
Correlating charge radius with quadrupole deformation and $B(E2)$ in
  atomic nuclei

abstract:
  A very good linear correlation is found between the four-point charge radius
relation $\delta R_{2p-2n}(Z,N)$ with that of quadrupole deformation data in
even-even nuclei. This results in a further improved charge radius relation
that holds in a precision of about 5$\times 10^{-3}$ fm. Such correlations are
also seen in global nuclear models, their precisions, however, are not enough
to be consistent with the experimental data. The new relation between charge
radii and deformation of even-even nuclei can be generalized to the reduced
electric quadrupole transition probability $B(E2)$ between the first $2^+$
state and the $0^+$ ground state, and the mean lifetime $\tau$ of the first
2$^+$ state.


title: Relational Models

abstract:
  We provide a survey on relational models. Relational models describe complete
networked {domains by taking into account global dependencies in the data}.
Relational models can lead to more accurate predictions if compared to
non-relational machine learning approaches. Relational models typically are
based on probabilistic graphical models, e.g., Bayesian networks, Markov
networks, or latent variable models. Relational models have applications in
social networks analysis, the modeling of knowledge graphs, bioinformatics,
recommendation systems, natural language processing, medical decision support,
and linked data.


title:
Honey: A dataflow programming language for the processing, featurization
  and analysis of multivariate, asynchronous and non-uniformly sampled scalar
  symbolic time sequences

abstract:
  We introduce HONEY; a new specialized programming language designed to
facilitate the processing of multivariate, asynchronous and non-uniformly
sampled symbolic and scalar time sequences. When compiled, a Honey program is
transformed into a static process flow diagram, which is then executed by a
virtual machine. Honey's most notable features are: (1) Honey introduces a new,
efficient and non-prone to error paradigm for defining recursive process flow
diagrams from text input with the mindset of imperative programming. Honey's
specialized, high level and concise syntax allows fast and easy writing,
reading and maintenance of complex processing of large scalar symbolic time
sequence datasets. (2) Honey guarantees programs will be executed similarly on
static or real-time streaming datasets. (3) Honey's IDE includes an interactive
visualization tool which allows for an interactive exploration of the
intermediate and final outputs. This combination enables fast incremental
prototyping, debugging, monitoring and maintenance of complex programs. (4) In
case of large datasets (larger than the available memory), Honey programs can
be executed to process input greedily. (5) The graphical structure of a
compiled program provides several desirable properties, including distributed
and/or paralleled execution, memory optimization, and program structure
visualization. (6) Honey contains a large library of both common and novel
operators developed through various research projects. An open source C++
implementation of Honey as well as the Honey IDE and the interactive data
visualizer are publicly available.


title:
SDSS-DR12 Bulk Stellar Spectral Classification: Artificial Neural
  Networks Approach

abstract:
  This paper explores the application of Probabilistic Neural Network (PNN),
Support Vector Machine (SVM) and Kmeans clustering as tools for automated
classification of massive stellar spectra.


title:
Divide and...conquer? On the limits of algorithmic approaches to
  syntactic semantic structure

abstract:
  In computer science, divide and conquer (D&C) is an algorithm design paradigm
based on multi-branched recursion. A D&C algorithm works by recursively and
monotonically breaking down a problem into sub problems of the same (or a
related) type, until these become simple enough to be solved directly. The
solutions to the sub problems are then combined to give a solution to the
original problem. The present work identifies D&C algorithms assumed within
contemporary syntactic theory, and discusses the limits of their applicability
in the realms of the syntax semantics and syntax morphophonology interfaces. We
will propose that D&C algorithms, while valid for some processes, fall short on
flexibility given a mixed approach to the structure of linguistic phrase
markers. Arguments in favour of a computationally mixed approach to linguistic
structure will be presented as an alternative that offers advantages to uniform
D&C approaches.


title:
A tool for stability and power sharing analysis of a generalized class
  of droop controllers for high-voltage direct-current transmission systems

abstract:
  The problem of primary control of high-voltage direct current transmission
systems is addressed in this paper, which contains four main contributions.
First, to propose a new nonlinear, more realistic, model for the system
suitable for primary control design, which takes into account nonlinearities
introduced by conventional inner controllers. Second, to determine necessary
conditions - dependent on some free controller tuning parameters - for the
existence of equilibria. Third, to formulate additional (necessary) conditions
for these equilibria to satisfy the power sharing constraints. Fourth, to
establish conditions for stability of a given equilibrium point. The usefulness
of the theoretical results is illustrated via numerical calculations on a
four-terminal example.


title:
A LSE and Sparse Message Passing-Based Channel Estimation for mmWave
  MIMO Systems

abstract:
  In this paper, we propose a novel channel estimation algorithm based on the
Least Square Estimation (LSE) and Sparse Message Passing algorithm (SMP), which
is of special interest for Millimeter Wave (mmWave) systems, since this
algorithm can leverage the inherent sparseness of the mmWave channel. Our
proposed algorithm will iteratively detect exact the location and the value of
non-zero entries of sparse channel vector without its prior knowledge of
distribution. The SMP is used to detect exact the location of non-zero entries
of the channel vector, while the LSE is used for estimating its value at each
iteration. Then, the analysis of the Cramer-Rao Lower Bound (CRLB) of our
proposed algorithm is given. Numerical experiments show that our proposed
algorithm has much better performance than the existing sparse estimators (e.g.
LASSO), especially when mmWave systems have massive antennas at both the
transmitters and receivers. In addition, we also find that our proposed
algorithm converges to the CRLB of the genie-aided estimation of sparse
channels in just a few turbo iterations.


title:
Direct Observation of Microstructures on Superconducting Single Crystals
  of K$_x$Fe$_{2-y}$Se$_2$

abstract:
  Potassium intercalated FeSe has been reported as a superconductor with
superconducting transition temperatures ($T_{\rm c}$'s) of 30-48 K. However,
there is no clear answer to identify the relationship between the surface
morphology, compositional ratio and its crystal structure. This report directly
reveals the correspondence among these three characteristics in single crystals
with a $T_{\rm c}$ onset of around 44 K using a micro-sampling technique.
Island-like parts on the surface of the crystals clearly have the
K$_x$Fe$_2$Se$_2$ structure with perfect FeSe layers, which is formed in
conjunction with the K$_2$Fe$_4$Se$_5$ phase. This results in the appearance of
the $T_{\rm c}$ onset of 44 K.


title: Holographic equipartition from first order action

abstract:
  In this paper, we get the holographic equipartition form the first order
formulism, that is, the connection and its conjugate momentum are considered to
be the canonical variables. The final results have similar structure as those
from the metric formulism.


title: Room-temperature superfluidity in a polariton condensate

abstract:
  Superfluidity---the suppression of scattering in a quantum fluid at
velocities below a critical value---is one of the most striking manifestations
of the collective behaviour typical of Bose-Einstein condensates. This
phenomenon, akin to superconductivity in metals, has until now only been
observed at prohibitively low cryogenic temperatures. For atoms, this limit is
imposed by the small thermal de Broglie wavelength, which is inversely related
to the particle mass. Even in the case of ultralight quasiparticles such as
exciton-polaritons, superfluidity has only been demonstrated at liquid helium
temperatures. In this case, the limit is not imposed by the mass, but instead
by the small exciton binding energy of Wannier-Mott excitons, which places the
upper temperature limit. Here we demonstrate a transition from normal to
superfluid flow in an organic microcavity supporting stable Frenkel
exciton-polaritons at room temperature. This result paves the way not only to
table-top studies of quantum hydrodynamics, but also to room-temperature
polariton devices that can be robustly protected from scattering.


title:
Doppler Tomography and Photometry of the Cataclysmic Variable 1RXS
  J064434.5+334451

abstract:
  We have obtained simultaneous photometric and spectroscopic observations of
the cataclysmic variable 1RXS J064434.5+334451. We have calibrated the spectra
for slit losses using the simultaneous photometry allowing to construct
reliable Doppler images from H$\alpha$ and HeII 4686 emission lines. We have
improved the ephemeris of the object based on new photometric eclipse timings,
obtaining $HJD = 2453403.759533 + 0.26937446E$. Some eclipses present a clear
internal structure which we attribute to a central HeII emission region
surrounding the white dwarf, a finding supported by the Doppler tomography.
This indicates that the system has a large inclination angle $i=78 \pm
2^{\circ}$. We have also analysed the radial velocity curve from the emission
lines to measure its semi--amplitude, $K_1$, from H$\alpha$ and HeII 4686 and
derive the masses of the components: $M_1=0.82\pm0.06$ M$_{\odot}$,
$M_2=0.78\pm0.04$ M$_{\odot}$ and their separation $a=2.01\pm0.06$ $R_{\odot}$.
The Doppler tomography and other observed features in this nova-like system
strongly suggests that this is a SW Sex-type system.


title:
On two questions concerning representations distinguished by the Galois
  involution

abstract:
  Let E/F be a quadratic extension of non-archimedean local fields of
characteristic 0. In this paper, we investigate two approaches which attempt to
describe the smooth irreducible representations of GL(n,E) that are
distinguished by its subgroup GL(n,F). One relates this class to
representations which come as base change lifts from a quasi-split unitary
group F, while another deals with a certain symmetry condition. By
characterizing the union of images of the base change maps we show that these
two approaches are closely related. Using this observation, we are able to
prove a statement relating base change and distinction for ladder
representations. We then produce a wide family of examples in which the
symmetry condition does not impose GL(n,F)-distinction, and thus exhibit the
limitations of these two approaches.


title: Aspects of Late-time Evolution in Mimetic $F(R)$ Gravity

abstract:
  We demonstrate how to describe in an unified way early and late-time
acceleration in the context of mimetic $F(R)$ gravity. As we show, an
exponential $F(R)$ gravity model has appealing features, with regard to
unification, and we perform an analysis of the late-time evolution. The
resulting picture is interesting since in the mimetic case, certain pathologies
of some ordinary $F(R)$ models are remedied in a consistent way, owing to the
presence of the mimetic potential and the Lagrange multiplier. We quantify the
late-time evolution analysis by studying the scaled dark energy density, the
dark energy equation of state and the total effective equation of state, and as
we show the late-time evolution is crucially affected by the functional form of
the $F(R)$ gravity. It is intriguing that the most appealing case corresponds
to the exponential $F(R)$ gravity which unifies late and early-time
acceleration. Finally, we study the behavior of the effective gravitational
constant and the growth factor, and as we show, significant differences between
the mimetic and ordinary $F(R)$ exponential model are spotted in the growth
factor.


title:
A centralized reinforcement learning method for multi-agent job
  scheduling in Grid

abstract:
  One of the main challenges in Grid systems is designing an adaptive,
scalable, and model-independent method for job scheduling to achieve a
desirable degree of load balancing and system efficiency. Centralized job
scheduling methods have some drawbacks, such as single point of failure and
lack of scalability. Moreover, decentralized methods require a coordination
mechanism with limited communications. In this paper, we propose a multi-agent
approach to job scheduling in Grid, named Centralized Learning Distributed
Scheduling (CLDS), by utilizing the reinforcement learning framework. The CLDS
is a model free approach that uses the information of jobs and their completion
time to estimate the efficiency of resources. In this method, there are a
learner agent and several scheduler agents that perform the task of learning
and job scheduling with the use of a coordination strategy that maintains the
communication cost at a limited level. We evaluated the efficiency of the CLDS
method by designing and performing a set of experiments on a simulated Grid
system under different system scales and loads. The results show that the CLDS
can effectively balance the load of system even in large scale and heavy loaded
Grids, while maintains its adaptive performance and scalability.


title:
On the Relation between the Minimum Principle and Dynamic Programming
  for Classical and Hybrid Control Systems

abstract:
  Hybrid optimal control problems are studied for a general class of hybrid
systems where autonomous and controlled state jumps are allowed at the
switching instants and in addition to terminal and running costs switching
between discrete states incurs costs. The statements of the Hybrid Minimum
Principle and Hybrid Dynamic Programming are presented in this framework and it
is shown that under certain assumptions the adjoint process in the Hybrid
Minimum Principle and the gradient of the value function in Hybrid Dynamic
Programming are governed by the same set of differential equations and have the
same boundary conditions and hence are almost everywhere identical to each
other along optimal trajectories. Analytic examples are provided to illustrate
the results and, in particular, a Riccati formalism for linear quadratic hybrid
tracking problems is presented.


title: A Smolin-like branching multiverse from multiscalar-tensor theory

abstract:
  We implement a Smolin-like branching multiverse through a directed, acyclic
graph of $N$ metrics. Our gravitational and matter actions are
indistinguishable from $N$ decoupled statements of General Relativity, if one
varies with respect to metric degrees of freedom. We replace $N-1$ metrics with
scalar fields by conformally relating each metric to its unique graph
predecessor. Varying with respect to the $N-1$ scalar fields gives a
multiscalar-tensor model which naturally features dark matter candidates.
Building atop an argument of Chapline and Laughlin, branching is accomplished
with the emergence of order parameters during gravitational collapse: we
bootstrap a suitably defined $N$ scalar field model with initial data from an
$N-1$ field model. We focus on the nearest-neighbour approximation, determine
conditions for dynamical stability, and compute the equations of motion. The
model features a novel screening property where the scalar fields actively
adjust to decouple themselves from the stress, oscillating about the requisite
values. In the Newtonian limit, these background values for the scalar fields
exactly reproduce Newton's law of gravitation.


title:
Effect of Wideband Beam Squint on Codebook Design in Phased-Array
  Wireless Systems

abstract:
  Analog beamforming with phased arrays is a promising technique for 5G
wireless communication at millimeter wave frequencies. Using a discrete
codebook consisting of multiple analog beams, each beam focuses on a certain
range of angles of arrival or departure and corresponds to a set of fixed phase
shifts across frequency due to practical hardware considerations. However, for
sufficiently large bandwidth, the gain provided by the phased array is actually
frequency dependent, which is an effect called beam squint, and this effect
occurs even if the radiation pattern of the antenna elements is frequency
independent. This paper examines the nature of beam squint for a uniform linear
array (ULA) and analyzes its impact on codebook design as a function of the
number of antennas and system bandwidth normalized by the carrier frequency.
The criterion for codebook design is to guarantee that each beam's minimum gain
for a range of angles and for all frequencies in the wideband system exceeds a
target threshold, for example 3 dB below the array's maximum gain. Analysis and
numerical examples suggest that a denser codebook is required to compensate for
beam squint. For example, 54% more beams are needed compared to a codebook
design that ignores beam squint for a ULA with 32 antennas operating at a
carrier frequency of 73 GHz and bandwidth of 2.5 GHz. Furthermore, beam squint
with this design criterion limits the bandwidth or the number of antennas of
the array if the other one is fixed.


title: Distributed algorithms for solving convex inequalities

abstract:
  In this paper, a distributed subgradient-based algorithm is proposed for
continuous-time multi-agent systems to search a feasible solution to convex
inequalities. The algorithm involves each agent achieving a state constrained
by its own inequalities while exchanging local information with other agents
under a time-varying directed communication graph. With the validity of a mild
connectivity condition associated with the communication graph, it is shown
that all agents will reach agreement asymptotically and the consensus state is
in the solution set of the inequalities. Furthermore, the method is also
extended to solving the distributed optimization problem of minimizing the sum
of local objective functions subject to convex inequalities. A simulation
example is presented to demonstrate the effectiveness of the theoretical
results.


title: Dedekind sums in the $p$-adic number field

abstract:
  In a recent note W. Kohnen asks whether the values of Dedekind sums are dense
in the field of $p$-adic numbers. The present paper answers this question.
Dedekind sums do not approximate units of $\mathbb Z_2$ or $\mathbb Z_3$, so
they are not dense in $\mathbb Q_2$ or $\mathbb Q_3$. But they are dense in
$\mathbb Q_p$ if $p\ge 5$.


title:
Second-order perturbation theory for 3He and pd scattering in pionless
  EFT

abstract:
  This work implements pionless effective field theory with the two-nucleon
system expanded around the unitarity limit at second order perturbation theory.
The expansion is found to converge well. All Coulomb effects are treated in
perturbation theory, including two-photon contributions at
next-to-next-to-leading order. After fixing a three-nucleon force to the 3He
binding energy at this order, proton-deuteron scattering in the doublet S-wave
channel is calculated for moderate center-of-mass momenta.


title:
On the Relationship between Online Gaussian Process Regression and
  Kernel Least Mean Squares Algorithms

abstract:
  We study the relationship between online Gaussian process (GP) regression and
kernel least mean squares (KLMS) algorithms. While the latter have no capacity
of storing the entire posterior distribution during online learning, we
discover that their operation corresponds to the assumption of a fixed
posterior covariance that follows a simple parametric model. Interestingly,
several well-known KLMS algorithms correspond to specific cases of this model.
The probabilistic perspective allows us to understand how each of them handles
uncertainty, which could explain some of their performance differences.


title:
Chromospheric Condensation and Quasi-periodic Pulsations in a
  Circular-ribbon Flare

abstract:
  In this paper, we report our multiwavelength observations of the C3.1
circular-ribbon flare SOL2015-10-16T10:20 in AR 12434. The flare consisted of a
circular flare ribbon (CFR), an inner flare ribbon (IFR) inside, and a pair of
short parallel flare ribbons (PFRs). During the impulsive phase of the flare,
"two-step" raster observations of \textit{IRIS} with a cadence of 6 s and an
exposure time of 2 s show plasma downflow at the CFR in the Si {\sc iv}
$\lambda$1402.77 line, suggesting chromospheric condensation. The downflow
speeds first increased rapidly from a few km s$^{-1}$ to the peak values of
45$-$52 km s$^{-1}$, before decreasing gradually to the initial levels. The
decay timescales of condensation were 3$-$4 minutes, indicating ongoing
magnetic reconnection. Interestingly, the downflow speeds are positively
correlated with logarithm of the Si {\sc iv} line intensity and time derivative
of the \textit{GOES} soft X-ray (SXR) flux in 1$-$8 {\AA}. The radio dynamic
spectra are characterized by a type \Rmnum{3} radio burst associated with the
flare, which implies that the chromospheric condensation was most probably
driven by nonthermal electrons. Using an analytical expression and the peak
Doppler velocity, we derived the lower limit of energy flux of the
precipitating electrons, i.e., 0.65$\times$10$^{10}$ erg cm$^{-2}$ s$^{-1}$.
The Si {\sc iv} line intensity and SXR derivative show quasi-periodic
pulsations with periods of 32$-$42 s.


title:
Crystal structure and anisotropic magnetic properties of new
  ferromagnetic Kondo lattice compound Ce(Cu,Al,Si)2

abstract:
  Single crystals of the new compound CeCu0.18Al0.24Si1.58 have been grown by
high-temperature solution growth method using a eutectic Al-Si mixture as flux.
This compound is derived from the binary CeSi2 (tetragonal ThSi2-type, Pearson
symbol tI12, space group I41/amd) obtained by partial substitution of Si by Cu
and Al atoms but showing full occupation of the Si crystal site (8e). While
CeSi2 is a well-known valence-fluctuating paramagnetic compound, the
CeCu0.18Al0.24Si1.58 phase orders ferromagnetically at TC = 9.3 K. At low
temperatures the easy-axis of magnetization is along the a-axis, which
re-orients itself along the c-axis above 30 K. The presence of hysteresis in
the magnetization curve, negative temperature coefficient of resistivity at
high temperatures, reduced jump in the heat capacity and a relatively lower
entropy released up to the ordering temperature, and enhanced Sommerfeld
coefficient (~100 mJ/mol K2) show that CeCu0.18Al0.24Si1.58 is a Kondo lattice
ferromagnetic, moderate heavy fermion compound. Analysis of the high
temperature heat capacity data in the paramagnetic region lets us infer that
the crystal electric field split doublet levels are located at 178 and 357 K,
respectively, and Kondo temperature (8.4 K) is of the order of TC in
CeCu0.18Al0.24Si1.58.


title: Model Selection for Treatment Choice: Penalized Welfare Maximization

abstract:
  This paper studies a penalized statistical decision rule for the treatment
assignment problem. Consider the setting of a utilitarian policy maker who must
use sample data to allocate a binary treatment to members of a population,
based on their observable characteristics. We model this problem as a
statistical decision problem where the policy maker must choose a subset of the
covariate space to assign to treatment, out of a class of potential subsets. We
focus on settings in which the policy maker may want to select amongst a
collection of constrained subset classes: examples include choosing the number
of covariates over which to perform best-subset selection, and model selection
when approximating a complicated class via a sieve. We adapt and extend results
from statistical learning to develop the Penalized Welfare Maximization (PWM)
rule. We establish an oracle inequality for the regret of the PWM rule which
shows that it is able to perform model selection over the collection of
available classes. We then use this oracle inequality to derive relevant bounds
on maximum regret for PWM. An important consequence of our results is that we
are able to formalize model-selection using a "hold-out" procedure, where the
policy maker would first estimate various policies using half of the data, and
then select the policy which performs the best when evaluated on the other half
of the data.


title: Devaney chaos plus shadowing implies distributional chaos

abstract:
  We explore connections among the regional proximal relation, the asymptotic
relation and the distal relation for a topological dynamical system with the
shadowing property, and show that if a Devaney chaotic system has the shadowing
property then it is distributionally chaotic.


title:
An asymptotically exact theory of functionally graded piezoelectric
  shells

abstract:
  An asymptotically exact two-dimensional theory of functionally graded
piezoelectric shells is derived by the variational-asymptotic method. The error
estimation of the constructed theory is given in the energetic norm. As an
application, analytical solution to the problem of forced vibration of a
functionally graded piezoceramic cylindrical shell with thickness polarization
fully covered by electrodes and excited by a harmonic voltage is found.


title:
Resonator reset in circuit QED by optimal control for large open quantum
  systems

abstract:
  We study an implementation of the open GRAPE (Gradient Ascent Pulse
Engineering) algorithm well suited for large open quantum systems. While
typical implementations of optimal control algorithms for open quantum systems
rely on explicit matrix exponential calculations, our implementation avoids
these operations leading to a polynomial speed-up of the open GRAPE algorithm
in cases of interest. This speed-up, as well as the reduced memory requirements
of our implementation, are illustrated by comparison to a standard
implementation of open GRAPE. As a practical example, we apply this open-system
optimization method to active reset of a readout resonator in circuit QED. In
this problem, the shape of a microwave pulse is optimized such as to empty the
cavity from measurement photons as fast as possible. Using our open GRAPE
implementation, we obtain pulse shapes leading to a reset time over four times
faster than passive reset.


title: Linear Stability of Rotating Black Holes: Outline of the Proof

abstract:
  After a brief introduction to the black hole stability problem, we outline
our recent proof of the linear stability of the non-extreme Kerr geometry.


title:
Asymptotics of the occupancy scheme in a random environment and its
  applications to tries

abstract:
  Consider $ m $ copies of an irreducible, aperiodic Markov chain $ Y $ taking
values in a finite state space. The asymptotics as $ m $ tends to infinity, of
the first time from which on the trajectories of the $ m $ copies differ, have
been studied by Szpankowski (1991) in the setting of tries. We use a different
approach and model the $ m $ trajectories by a variant of the occupancy scheme,
where we consider a nested sequence of boxes. This approach will enable us to
extend the result to the case when the transition probabilities are random. We
moreover use the same techniques to study the asymptotics as $ m $ tends to
infinity of the time up to which we have observed all the possible trajectories
of $ Y $ in random and nonrandom scenery.


title:
On locality of Generalized Reed-Muller codes over the broadcast erasure
  channel

abstract:
  One to Many communications are expected to be among the killer applications
for the currently discussed 5G standard. The usage of coding mechanisms is
impacting broadcasting standard quality, as coding is involved at several
levels of the stack, and more specifically at the application layer where
Rateless, LDPC, Reed Solomon codes and network coding schemes have been
extensively studied, optimized and standardized in the past. Beyond reusing,
extending or adapting existing application layer packet coding mechanisms based
on previous schemes and designed for the foregoing LTE or other broadcasting
standards; our purpose is to investigate the use of Generalized Reed Muller
codes and the value of their locality property in their progressive decoding
for Broadcast/Multicast communication schemes with real time video delivery.
Our results are meant to bring insight into the use of locally decodable codes
in Broadcasting.


title:
Probing Quantum Correlation Functions Through Energy Absorption
  Interferometry

abstract:
  An interferometric technique is proposed for determining the spatial forms of
the individual degrees of freedom through which a many body system can absorb
energy from its environment. The method separates out the coherent excitations
present at any given frequency; it is not necessary to infer modal content from
spectra. The system under test is excited with two external sources, which
create generalized forces, and the fringe in the total power dissipated is
measured as the relative phase between the sources is varied. If the complex
fringe visibility is measured for different pairs of source locations, the
anti-Hermitian part of the complex-valued non-local correlation tensor can be
determined, which can then be decomposed to give the natural dynamical modes of
the system and their relative responsivities. If each source in the
interferometer creates a different kind of force, the spatial forms of the
individual excitations that are responsible for cross-correlated response can
be found. The technique is a generalization of holography because it measures
the state of coherence to which the system is maximally sensitive. It can be
applied across a wide range of wavelengths, in a variety of ways, to
homogeneous media, thin films, patterned structures, and to components such as
sensors, detectors and energy harvesting absorbers.


title:
Inversion of the attenuated V-line transform for SPECT with Compton
  cameras

abstract:
  The Compton camera is a promising alternative to the Anger camera for imaging
gamma radiation, with the potential to significantly increase the sensitivity
of SPECT. Two-dimensional Compton camera image reconstruction can be
implemented by inversion of the V-line transform, which integrates the emission
distribution over V-lines (unions of two half-lines), that have vertices on a
surrounding detector array. Inversion of the V-line transform without
attenuation has recently been addressed by several authors. However, it is well
known from standard SPECT that ignoring attenuation can significantly degrade
the quality of the reconstructed image. In this paper we address this issue and
study the attenuated V-line transform accounting for attenuation of photons in
SPECT with Compton cameras. We derive an analytic inversion approach based on
circular harmonics expansion, and show uniqueness of reconstruction for the
attenuated V-line transform. We further develop a discrete image reconstruction
algorithm based on our analytic studies, and present numerical results that
demonstrate the effectiveness of our algorithm.


title: E3 : Keyphrase based News Event Exploration Engine

abstract:
  This paper presents a novel system E3 for extracting keyphrases from news
content for the purpose of offering the news audience a broad overview of news
events, with especially high content volume. Given an input query, E3 extracts
keyphrases and enrich them by tagging, ranking and finding role for frequently
associated keyphrases. Also, E3 finds the novelty and activeness of keyphrases
using news publication date, to identify the most interesting and informative
keyphrases.


title: Dust in three dimensions in the Galactic Plane

abstract:
  We present three dimensional maps in monochromatic extinction $A_{\rm 0}$ and
the extinction parameter $R_0$ within a few degrees of the Galactic plane.
These are inferred using photometry from the Pan-STARRS1 and Spitzer Glimpse
surveys of nearly $20$ million stars located in the region $l = 0-250^{\circ}$
and from $b = -4.5^{\circ}$ to $b=4.5^{\circ}$. Given the available stellar
number density, we use an angular resolution of $7' \times 7'$ and steps of
$1{\rm mag}$ in distance modulus. We simultaneously estimate distance modulus
and effective temperature $T_{\rm eff}$ alongside the other parameters for
stars individually using the method of \citet{Hanson2014} before combining
these estimates to a complete map. The full maps are available via the MNRAS
website.


title:
Parameter estimation in the presence of the most general Gaussian
  dissipative reservoir

abstract:
  We analyze the performance of quantum parameter estimation in the presence of
the most general Gaussian dissipative reservoir. We derive lower bounds on the
precision of phase estimation and a closely related problem of frequency
estimation. For both problems we show that it is impossible to achieve the
Heisenberg limit asymptotically in the presence of such a reservoir. However,
we also find that for any fixed number of probes used in the setup there exists
a Gaussian dissipative reservoir, which, in principle, allows for the
Heisenberg-limited performance for that number of probes. We discuss a
realistic implementation of a frequency estimation scheme in the presence of a
Gaussian dissipative reservoir in a cavity system.


title:
Star formation associated with neutral hydrogen in the outskirts of
  early-type galaxies

abstract:
  About 20 percent of all nearby early-type galaxies ($M_{\star} \gtrsim 6
\times 10^{9}$ M$_{\odot}$) outside the Virgo cluster are surrounded by a disc
or ring of low-column-density neutral hydrogen (HI) gas with typical radii of
tens of kpc, much larger than the stellar body. In order to understand the
impact of these gas reservoirs on the host galaxies, we analyse the
distribution of star formation out to large radii as a function of HI
properties using GALEX UV and SDSS optical images. Our sample consists of 18
HI-rich galaxies as well as 55 control galaxies where no HI has been detected.
In half of the HI-rich galaxies the radial UV profile changes slope at the
position of the HI radial profile peak. To study the stellar populations, we
calculate the FUV-NUV and UV-optical colours in two apertures, 1-3 and 3-10
R$_{eff}$ . We find that HI -rich galaxies are on average 0.5 and 0.8 mag bluer
than the HI-poor ones, respectively. This indicates that a significant fraction
of the UV emission traces recent star formation and is associated with the HI
gas. Using FUV emission as a proxy for star formation, we estimate the
integrated star formation rate in the outer regions (R > 1R$_{eff}$) to be on
average $6 \times 10^{-3}$ M$_{\odot}$ yr$^{-1}$ for the HI-rich galaxies. This
rate is too low to build a substantial stellar disc and, therefore, change the
morphology of the host. We find that the star formation efficiency and the gas
depletion time are similar to those at the outskirts of spirals.


title: High dimensionality and h-principle in PDE

abstract:
  In this note we would like to present "an analysts' point of view" on the
Nash-Kuiper theorem and in particular highlight the very close connection to
some aspects of turbulence -- a paradigm example of a high-dimensional
phenomenon.


title: Rank-two vector bundles on non-minimal ruled surfaces

abstract:
  We continue previous works by various authors and study the birational
geometry of moduli spaces of stable rank-two vector bundles on surfaces with
Kodaira dimension $-\infty$. To this end, we express vector bundles as natural
extensions, by using two numerical invariants associated to vector bundles,
similar to the invariants defined by Brinzanescu and Stoia in the case of
minimal surfaces. We compute explicitly these natural extensions on blowups of
general points on a minimal surface. In the case of rational surfaces, we prove
that any irreducible component of a moduli space is either rational or stably
rational.


title: Importance sampling of heavy-tailed iterated random functions

abstract:
  We consider a stochastic recurrence equation of the form $Z_{n+1} = A_{n+1}
Z_n+B_{n+1}$, where $\mathbb{E}[\log A_1]<0$, $\mathbb{E}[\log^+ B_1]<\infty$
and $\{(A_n,B_n)\}_{n\in\mathbb{N}}$ is an i.i.d. sequence of positive random
vectors. The stationary distribution of this Markov chain can be represented as
the distribution of the random variable $Z \triangleq \sum_{n=0}^\infty
B_{n+1}\prod_{k=1}^nA_k$. Such random variables can be found in the analysis of
probabilistic algorithms or financial mathematics, where $Z$ would be called a
stochastic perpetuity. If one interprets $-\log A_n$ as the interest rate at
time $n$, then $Z$ is the present value of a bond that generates $B_n$ unit of
money at each time point $n$. We are interested in estimating the probability
of the rare event $\{Z>x\}$, when $x$ is large; we provide a consistent
simulation estimator using state-dependent importance sampling for the case,
where $\log A_1$ is heavy-tailed and the so-called Cram\'{e}r condition is not
satisfied. Our algorithm leads to an estimator for $P(Z>x)$. We show that under
natural conditions, our estimator is strongly efficient. Furthermore, we extend
our method to the case, where $\{Z_n\}_{n\in\mathbb{N}}$ is defined via the
recursive formula $Z_{n+1}=\Psi_{n+1}(Z_n)$ and $\{\Psi_n\}_{n\in\mathbb{N}}$
is a sequence of i.i.d. random Lipschitz functions.


title: Hamiltonian-based Algorithm for Relaxed Optimal Control

abstract:
  This paper concerns a first-order algorithmic technique for a class of
optimal control problems defined on switched-mode hybrid systems. The salient
feature of the algorithm is that it avoids the computation of Fr\'echet or
G\^ateaux derivatives of the cost functional, which can be time consuming, but
rather moves in a projected-gradient direction that is easily computable (for a
class of problems) and does not require any explicit derivatives. The algorithm
is applicable to a class of problems where a pointwise minimizer of the
Hamiltonian is computable by a simple formula, and this includes many problems
that arise in theory and applications. The natural setting for the algorithm is
the space of continuous-time relaxed controls, whose special structure renders
the analysis simpler than the setting of ordinary controls. While the space of
relaxed controls has theoretical advantages, its elements are abstract entities
that may not be amenable to computation. Therefore, a key feature of the
algorithm is that it computes adequate approximations to relaxed controls
without loosing its theoretical convergence properties. Simulation results,
including cpu times, support the theoretical developments.


title:
Optimal User Loading in Massive MIMO Systems with Regularized Zero
  Forcing Precoding

abstract:
  We consider a downlink multiuser multiple-input multiple output (MIMO) system
employing regularized zero-forcing (RZF) precoding. We derive the asymptotic
signal-to-leakage-plus-noise ratio (SLNR) as both the number of antennas and
the number of users go to infinity at a fixed ratio. Focusing on the symmetric
uncorrelated channels, we show that the SLNR is asymptotically equal to
signal-to-interference-plus-noise ratio (SINR) which allows us to optimize the
user loading for spectral efficiency. The results show that the optimal user
loading varies depending on the channel signal-to-noise ratio (SNR) but is
equal to one in both the low or high SNR regimes.


title: A Generalization of Bernstein-Vazirani Algorithm to Qudit Systems

abstract:
  A quantum algorithm to solve the parity problem is better than its most
efficient classical counter- part with a separation that is polynomial in the
number of queries. This was shown by E. Bernstein and U. Vazirani and was one
of the earliest indications that the quantum information processing can
outperform the classical one by a significant margin. The problem and its
solution both is usually stated for a 2-level system since we generally work
with bits/qubits. However, many works have been done generalizing known quantum
computing techniques to higher level systems. Following this, we look at a
generalization of the Bernstein-Vazirani algorithm implemented on a general
qudit system.


title:
Governing equations for Probability densities of stochastic differential
  equations with discrete time delays

abstract:
  The time evolution of probability densities for solutions to stochastic
differential equations (SDEs) without delay is usually described by
Fokker-Planck equations, which require the adjoint of the infinitesimal
generator for the solutions. However, Fokker-Planck equations do not exist for
stochastic delay differential equations (SDDEs) because the solutions to SDDEs
are not Markov processes and have no corresponding infinitesimal generators. In
this paper, we address the open question of finding the governing equations for
probability densities of SDDEs with discrete time delays. The governing
equation is given in a simple form that facilitates theoretical analysis and
numerical computation. An illustrative example is presented to verify the
proposed governing equations.


title:
Presentation of the Iwasawa algebra of the first congruence kernel of a
  semi-simple, simply connected Chevalley group over $\mathbb{Z}_p$

abstract:
  It is a general principle that objects coming from semi-simple, simply
connected (split) groups have explicit presentations like Serre's presentation
of semi-simple algebras and Steinberg's presentation of Chevalley groups. In
this paper we give an explicit presentation (by generators and relations) of
the Iwasawa algebra for the first congruence kernel of a semi-simple, simply
connected Chevalley group over $\mathbb{Z}_p$, extending the proof given by
Clozel for the group $\Gamma_1(SL_2(\mathbb{Z}_p))$, the first congruence
kernel of $SL_2(\mathbb{Z}_p)$ for primes $p>2$.


title: On the distribution of $\alpha p^{\gamma}+\beta$ modulo one

abstract:
  Let $\|\cdot\|$ denote the minimum distance to an integer. For $0<\gamma< 1$,
$\theta>0$ and $(\alpha, \beta) \in \mathbb{R} \setminus \{0\} \times
\mathbb{R}$ we study when \begin{equation*} \|\alpha p^{\gamma}+\beta
\|<p^{-\theta}, \end{equation*} holds for infinitely many primes $p$ of a
special type. In particular, we consider when this inequality holds for primes
$p$ such that $p+2$ has few prime factors counted with multiplicity. This is
done using an exponential sum estimate of the author and the linear sieve of
Iwaniec with bilinear error term. This is related to recent work of Tolev,
Todorova, Mat\"{o}maki and Cai.


title:
Radiation Like Scalar Field and Gauge Fields in Cosmology for a theory
  with Dynamical Time

abstract:
  Cosmological solutions with a scalar field behaving as radiation are
obtained, in the context of gravitational theory with dynamical time. The
solution requires the spacial curvature of the universe k, to be zero, unlike
the standard radiation solutions, which do not impose any constraint on the
spacial curvature of the universe. This is because only such $ k=0 $ radiation
solutions poses a homothetic Killimg vector. This kind of theory can be used to
generalize electromagnetism and other gauge theories, in curved space time, and
there are no deviations from standard gauge filed equation (like Maxwell
equations) in the case there exist a conformal Killing vector. But there could
be departures from Maxwell and Yang Mills equations, for more general space
times.


title:
On Natural Deduction for Herbrand Constructive Logics I: Curry-Howard
  Correspondence for Dummett's Logic LC

abstract:
  Dummett's logic LC is intuitionistic logic extended with Dummett's axiom: for
every two statements the first implies the second or the second implies the
first. We present a natural deduction and a Curry-Howard correspondence for
first-order and second-order Dummett's logic. We add to the lambda calculus an
operator which represents, from the viewpoint of programming, a mechanism for
representing parallel computations and communication between them, and from the
viewpoint of logic, Dummett's axiom. We prove that our typed calculus is
normalizing and show that proof terms for existentially quantified formulas
reduce to a list of individual terms forming an Herbrand disjunction.


title:
When categorization-based stranger avoidance explains the uncanny
  valley: A comment on MacDorman & Chattopadhyay (2016)

abstract:
  Artificial objects often subjectively look eerie when their appearance to
some extent resembles a human, which is known as the uncanny valley phenomenon.
From a cognitive psychology perspective, several explanations of the phenomenon
have been put forth, two of which are object categorization and realism
inconsistency. Recently, MacDorman and Chattopadhyay (2016) reported
experimental data as evidence in support of the latter. In our estimation,
however, their results are still consistent with categorization-based stranger
avoidance. In this Discussions paper, we try to describe why
categorization-based stranger avoidance remains a viable explanation, despite
the evidence of MacDorman and Chattopadhyay, and how it offers a more inclusive
explanation of the impression of eeriness in the uncanny valley phenomenon.


title:
On the Irreducibility of the Complex Specialization of the
  Representation of The Hecke Algebra of the Complex Reflection Group $G_7$

abstract:
  We consider a 2-dimensional representation of the Hecke algebra
$\mathcal{H}(G_7, u)$, where $G_7$ is the complex reflection group and $u$ is
the set of indeterminates $u=(x_1, x_2, y_1, y_2, y_3, z_1, z_2, z_3)$. After
specializing the indetrminates to non zero complex numbers, we then determine a
necessary and sufficient condition that guarantees the irreducibility of the
complex specialization of the representation of the Hecke algebra $H(G_7, u)$.


title: Wav2Letter: an End-to-End ConvNet-based Speech Recognition System

abstract:
  This paper presents a simple end-to-end model for speech recognition,
combining a convolutional network based acoustic model and a graph decoding. It
is trained to output letters, with transcribed speech, without the need for
force alignment of phonemes. We introduce an automatic segmentation criterion
for training from sequence annotation without alignment that is on par with CTC
while being simpler. We show competitive results in word error rate on the
Librispeech corpus with MFCC features, and promising results from raw waveform.


title:
Network Utility Maximization Revisited: Three Issues and Their
  Resolution

abstract:
  Distributed and iterative network utility maximization algorithms, such as
the primal-dual algorithms or the network-user decomposition algorithms, often
involve trajectories where the iterates may be infeasible, convergence to the
optimal points of relaxed problems different from the original, or convergence
to local maxima. In this paper, we highlight the three issues with iterative
algorithms. We then propose a distributed and iterative algorithm that does not
suffer from the three issues. In particular, we assert the feasibility of the
algorithm's iterates at all times, convergence to the global maximum of the
given problem (rather than to global maximum of a relaxed problem), and
avoidance of any associated spurious rest points of the dynamics. A benchmark
algorithm due to Kelly, Maulloo and Tan (1998) [Rate control for communication
networks: shadow prices, proportional fairness and stability, Journal of the
Operational Research Society, 49(3), 237-252] involves fast user updates
coupled with slow network updates in the form of additive-increase
multiplicative-decrease of suggested user flows. The proposed algorithm may be
viewed as one with fast user updates and fast network updates that keeps the
iterates feasible at all times. Simulations suggest that the convergence rate
of the ordinary differential equation (ODE) tracked by our proposed algorithm's
iterates is comparable to that of the ODE for the aforementioned benchmark
algorithm.


title:
Masses and Ages for 230,000 LAMOST Giants, via Their Carbon and Nitrogen
  Abundances

abstract:
  We measure carbon and nitrogen abundances to $\lesssim$ 0.1 dex for 450,000
giant stars from their low-resolution (R$\sim$1800) LAMOST DR2 survey spectra.
We use these [C/M] and [N/M] measurements, together with empirical relations
based on the APOKASC sample, to infer stellar masses and implied ages for
230,000 of these objects to 0.08 dex and 0.2 dex respectively. We use The
Cannon, a data-driven approach to spectral modeling, to construct a predictive
model for LAMOST spectra. Our reference set comprises 8125 stars observed in
common between the APOGEE and LAMOST surveys, taking seven APOGEE DR12 labels
(parameters) as ground truth: Teff, logg, [M/H], [$\alpha$/M], [C/M], [N/M],
and Ak. We add seven colors to the Cannon model, based on the g, r, i, J, H, K,
W1, and W2 magnitudes from APASS, 2MASS & WISE, which improves our constraints
on Teff and logg by up to 20% and on Ak by up to 70%. Cross-validation of the
model demonstrates that, for high-SNR objects, our inferred labels agree with
the APOGEE values to within 50 K in temperature, 0.04 magnitudes in Ak, and <
0.1 dex in logg, [M/H], [C/M], [N/M], and [$\alpha$/M]. We apply the model to
450,000 giants in LAMOST DR2 that have not been observed by APOGEE. This
demonstrates that precise individual abundances can be measured from
low-resolution spectra, and represents the largest catalog of [C/M], [N/M],
masses and ages to date. As as result, we greatly increase the number and sky
coverage of stars with mass and age estimates.


title: Bichromatic homodyne detection of broadband quadrature squeezing

abstract:
  We experimentally study a homodyne detection technique for the
characterization of a quadrature squeezed field where the correlated bands,
here created by four-wave mixing in a hot atomic vapor, are separated by a
large frequency gap of more than 6 GHz. The technique uses a two-frequency
local oscillator to detect the fluctuations of the correlated bands at a
frequency accessible to the detection electronics. Working at low detection
frequency, the method allows for the determination of both the amplitude and
the phase of the squeezing spectrum. In particular, we show that the quadrature
squeezing created by our four-wave mixing process displays a noise ellipse
rotation of $\pi/2$ across the squeezing spectrum