title: The expanding search ratio of a graph

abstract:
  We study the problem of searching for a hidden target in an environment that
is modeled by an edge-weighted graph. A sequence of edges is chosen starting
from a given root vertex such that each edge is adjacent to a previously chosen
edge. This search paradigm, known as expanding search was recently introduced
by Apern and Lidbetter [2013] for modeling problems such as searching for coal
or minesweeping in which the cost of re-exploration is negligible. It can also
be used to model a team of searchers successively splitting up in the search
for a hidden adversary or explosive device, for example. We define the search
ratio of an expanding search as the maximum over all vertices of the ratio of
the time taken to reach the vertex and the shortest-path cost to it from the
root. This can be interpreted as a measure of the multiplicative regret
incurred in searching, and similar objectives have previously been studied in
the context of conventional (pathwise) search. In this paper we address
algorithmic and computational issues of minimizing the search ratio over all
expanding searches, for a variety of search environments, including general
graphs, trees and star-like graphs. Our main results focus on the problem of
finding the randomized expanding search with minimum expected search ratio,
which is equivalent to solving a zero-sum game between a Searcher and a Hider.
We solve these problems for certain classes of graphs, and obtain
constant-factor approximations for others.


title: Redundant Array Configurations for 21 cm Cosmology

abstract:
  Realizing the potential of 21 cm tomography to statistically probe the
intergalactic medium before and during the Epoch of Reionization requires large
telescopes and precise control of systematics. Next-generation telescopes are
now being designed and built to meet these challenges, drawing lessons from
first-generation experiments that showed the benefits of densely packed, highly
redundant arrays--in which the same mode on the sky is sampled by many antenna
pairs--for achieving high sensitivity, precise calibration, and robust
foreground mitigation. In this work, we focus on the Hydrogen Epoch of
Reionization Array (HERA) as an interferometer with a dense, redundant core
designed following these lessons to be optimized for 21 cm cosmology. We show
how modestly supplementing or modifying a compact design like HERA's can still
deliver high sensitivity while enhancing strategies for calibration and
foreground mitigation. In particular, we compare the imaging capability of
several array configurations, both instantaneously (to address instrumental and
ionospheric effects) and with rotation synthesis (for foreground removal). We
also examine the effects that configuration has on calibratability using
instantaneous redundancy. We find that improved imaging with sub-aperture
sampling via "off-grid" antennas and increased angular resolution via far-flung
"outrigger" antennas is possible with a redundantly calibratable array
configuration.


title:
Checking Dynamic Consistency of Conditional Hyper Temporal Networks via
  Mean Payoff Games (Hardness and (pseudo) Singly-Exponential Time Algorithm)

abstract:
  In this work we introduce the \emph{Conditional Hyper Temporal Network
(CHyTN)} model, which is a natural extension and generalization of both the
\CSTN and the \HTN model. Our contribution goes as follows. We show that
deciding whether a given \CSTN or CHyTN is dynamically consistent is
\coNP-hard. Then, we offer a proof that deciding whether a given CHyTN is
dynamically consistent is \PSPACE-hard, provided that the input instances are
allowed to include both multi-head and multi-tail hyperarcs. In light of this,
we continue our study by focusing on CHyTNs that allow only multi-head or only
multi-tail hyperarcs, and we offer the first deterministic (pseudo)
singly-exponential time algorithm for the problem of checking the
dynamic-consistency of such CHyTNs, also producing a dynamic execution strategy
whenever the input CHyTN is dynamically consistent. Since \CSTN{s} are a
special case of CHyTNs, this provides as a byproduct the first
sound-and-complete (pseudo) singly-exponential time algorithm for checking
dynamic-consistency in CSTNs. The proposed algorithm is based on a novel
connection between CSTN{s}/CHyTN{s} and Mean Payoff Games. The presentation of
the connection between \CSTN{s}/CHyTNs and \MPG{s} is mediated by the \HTN
model. In order to analyze the algorithm, we introduce a refined notion of
dynamic-consistency, named $\epsilon$-dynamic-consistency, and present a sharp
lower bounding analysis on the critical value of the reaction time
$\hat{\varepsilon}$ where a \CSTN/CHyTN transits from being, to not being,
dynamically consistent. The proof technique introduced in this analysis of
$\hat{\varepsilon}$ is applicable more generally when dealing with linear
difference constraints which include strict inequalities.


title:
Dynamical decoupling sequences for multi-qubit dephasing suppression and
  long-time quantum memory

abstract:
  We consider a class of multi-qubit dephasing models that combine classical
noise sources and linear coupling to a bosonic environment, and are controlled
by arbitrary sequences of dynamical decoupling pulses. Building on a general
transfer filter-function framework for open-loop control, we provide an exact
representation of the controlled dynamics for arbitrary stationary non-Gaussian
classical and quantum noise statistics, with analytical expressions emerging
when all dephasing sources are Gaussian. This exact characterization is used to
establish two main results. First, we construct multi-qubit sequences that
ensure maximum high-order error suppression in both the time and frequency
domain and that can be exponentially more efficient than existing ones in terms
of total pulse number. Next, we show how long-time multi-qubit storage may be
achieved by meeting appropriate conditions for the emergence of a fidelity
plateau under sequence repetition, thereby generalizing recent results for
single-qubit memory under Gaussian dephasing. In both scenarios, the key step
is to endow multi-qubit sequences with a suitable displacement anti-symmetry
property, which is of independent interest for applications ranging from
environment-assisted entanglement generation to multi-qubit noise spectroscopy
protocols.


title: Optimal synchronization of directed complex networks

abstract:
  We study optimal synchronization of networks of coupled phase oscillators. We
extend previous theory for optimizing the synchronization properties of
undirected networks to the important case of directed networks. We derive a
generalized synchrony alignment function that encodes the interplay between
network structure and the oscillators' natural frequencies and serves as an
objective measure for the network's degree of synchronization. Using the
generalized synchrony alignment function, we show that a network's
synchronization properties can be systematically optimized. This framework also
allows us to study the properties of synchrony-optimized networks, and in
particular, investigate the role of directed network properties such as nodal
in- and out-degrees. For instance, we find that in optimally rewired networks
the heterogeneity of the in-degree distribution roughly matches the
heterogeneity of the natural frequency distribution, but no such relationship
emerges for out-degrees. We also observe that a network's synchronization
properties are promoted by a strong correlation between the nodal in-degrees
and the natural frequencies of oscillators, whereas the relationship between
the nodal out-degrees and the natural frequencies has comparatively little
effect. This result is supported by our theory, which indicates that
synchronization is promoted by a strong alignment of the natural frequencies
with the left singular vectors corresponding to the largest singular values of
the Laplacian matrix.


title:
Phase manipulation of terahertz waves by work function engineering in
  metal-graphite structures

abstract:
  We manipulate the transient terahertz (THz) waves emitted from metal-graphite
interfaces, where potential barriers were formed because of work function
differences. To adaptively control the phase of the THz waves, two distinct
groups of metals were evaporated on n-type doped highly oriented pyrolytic
graphite (HOPG): group A, which consisted of Pt, Au, and Ag with work functions
larger than that of HOPG and group B, which consisted of Al and Ti with work
functions smaller than that of HOPG. The phase of the transient THz lineshapes
from group A was opposite to that of group B under infrared laser excitation,
which is indicative of opposite band bending and concomitant interfacial doping
for ambipolar transport at the metal-graphite junctions. The amplitude of the
THz waves could be further substantiated by the work function differences and
modified minority carrier mobilities at the depletion regions.


title: Comment on article "Line of Dirac Nodes in Hyperhoneycomb Lattices"

abstract:
  Recently, carbon hyperhoneycomb ($\mathcal{H}$-n) lattices have been proposed
to be, through a one-$p$ orbital tight-binding (TB) model with nearest-neighbor
(n.n.) hopping, a family of strong 3D topological insulators (K. Mullen, B.
Uchoa and D. T. Glatzhofer, Phys. Rev. Lett. 115, 026403 (2015)) . In this
Comment we show, through Density Functional Theory (DFT) and Extended H\"uckel
Theory (EHT) calculations for the $\mathcal{H}$-0 lattice, that the TB
Hamiltonian used by the authors is inadequate, invalidating the presented
conclusions.


title:
Molecular dynamics simulation of gold cluster growth during sputter
  deposition

abstract:
  We present a molecular dynamics simulation scheme that we apply to study the
time evolution of the self-organized growth process of metal cluster assemblies
formed by sputter-deposited gold atoms on a planar surface. The simulation
model incorporates the characteristics of the plasma-assisted deposition
process and allows for an investigation over a wide range of deposition
parameters. It is used to obtain data for the cluster properties which can
directly be compared to recently published experimental data for gold on
polystyrene (M. Schwartzkopf \textit{et al}., ACS Appl. Mater. Interfaces
\textbf{7}, 13547 (2015)). While good agreement is found between the two, the
simulations additionally provide valuable time-dependent real-space data of the
surface morphology some of whose details are hidden in the reciprocal-space
scattering images that were used for the experimental analysis.


title:
Impact of overlapping resonances on magnetoassociation of cold molecules
  in tight traps

abstract:
  Overlapping Feshbach resonances are commonly observed in experiments with
ultracold atoms and can influence the molecule production process. We derive an
effective approach to describe magnetoassociation in an external trap in the
presence of multiple overlapping resonances. We study how the strength and
shape of the trap affects the energy level structure and demonstrate the
existence of a regime in which the conventional two-channel Landau-Zener
description of the molecule production process breaks down.


title: A population of eruptive variable protostars in VVV

abstract:
  We present the discovery of 816 high amplitude infrared variable stars
($\Delta K_{\rm s} >$ 1 mag) in 119 deg$^2$ of the Galactic midplane covered by
the Vista Variables in the Via Lactea (VVV) survey. Almost all are new
discoveries and about 50$\%$ are YSOs. This provides further evidence that YSOs
are the commonest high amplitude infrared variable stars in the Galactic plane.
In the 2010-2014 time series of likely YSOs we find that the amplitude of
variability increases towards younger evolutionary classes (class I and
flat-spectrum sources) except on short timescales ($<$25 days) where this trend
is reversed. Dividing the likely YSOs by light curve morphology, we find 106
with eruptive light curves, 45 dippers, 39 faders, 24 eclipsing binaries, 65
long-term periodic variables (P$>$100 days) and 162 short-term variables.
Eruptive YSOs and faders tend to have the highest amplitudes and eruptive
systems have the reddest SEDs. Follow up spectroscopy in a companion paper
verifies high accretion rates in the eruptive systems. Variable extinction is
disfavoured by the 2 epochs of colour data. These discoveries increase the
number of eruptive variable YSOs by a factor of at least 5, most being at
earlier stages of evolution than the known FUor and EXor types. We find that
eruptive variability is at least an order of magnitude more common in class I
YSOs than class II YSOs. Typical outburst durations are 1 to 4 years, between
those of EXors and FUors. They occur in 3 to 6\% of class I YSOs over a 4 year
time span.


title:
Classical solution to a multidimensional stochastic Burgers equation via
  forward-backward SDEs

abstract:
  In this paper, we address the problem of existence and uniqueness of a global
classical solution to a multidimensional stochastic Burgers equation without
gradient-type assumptions on the force or the initial condition. The equation
is first transformed to a random PDE, and then solved via the associated
forward-backward SDE. Additionally, we obtain a new a priori gradient estimate
valid for a large class of second-order quasilinear parabolic PDEs which
becomes an important tool in our approach. Also, we study the stochastic
Burgers equation in the vanishing viscosity limit.


title: Infrared spectroscopy of eruptive variable protostars from VVV

abstract:
  In a companion work (Paper I) we detected a large population of highly
variable Young Stellar Objects (YSOs) in the Vista Variables in the Via Lactea
(VVV) survey, typically with class I or flat spectrum spectral energy
distributions and diverse light curve types. Here we present infrared spectra
(0.9--2.5 $\mu$m) of 37 of these variables, many of them observed in a bright
state. The spectra confirm that 15/18 sources with eruptive light curves have
signatures of a high accretion rate, either showing EXor-like emission features
($\Delta$v=2 CO, Br$\gamma$) and/or FUor-like features ($\Delta$v=2 CO and
H$_{2}$O strongly in absorption). Similar features were seen in some long term
periodic YSOs and faders but not in dippers or short-term variables. The sample
includes some dusty Mira variables (typically distinguished by smooth Mira-like
light curves), 2 cataclysmic variables and a carbon star. In total we have
added 19 new objects to the broad class of eruptive variable YSOs with episodic
accretion. Eruptive variable YSOs in our sample that were observed at bright
states show higher accretion luminosities than the rest of the sample. Most of
the eruptive variables differ from the established FUor and EXor subclasses,
showing intermediate outburst durations and a mixture of their spectroscopic
characteristics. This is in line with a small number of other recent
discoveries. Since these previously atypical objects are now the majority
amongst embedded members of the class, we propose a new classification for them
as MNors. This term (pronounced emnor) follows V1647 Ori, the illuminating star
of McNeil's Nebula.


title: Automation of NLO processes and decays and POWHEG matching in WHIZARD

abstract:
  We give a status report on the automation of next-to-leading order processes
within the Monte Carlo event generator WHIZARD, using GoSam and OpenLoops as
provider for one-loop matrix elements. To deal with divergences, WHIZARD uses
automated FKS subtraction, and the phase space for singular regions is
generated automatically. NLO examples for both scattering and decay processes
with a focus on e+e- processes are shown. Also, first NLO-studies of
observables for collisions of polarized leptons beams, e.g. at the ILC, will be
presented. Furthermore, the automatic matching of the fixed-order NLO
amplitudes with emissions from the parton shower within the POWHEG formalism
inside WHIZARD will be discussed. We also present results for top pairs at
threshold in lepton collisions, including matching between a resummed threshold
calculation and fixed-order NLO. This allows the investigation of more
exclusive differential observables.


title: Measuring the scrambling of quantum information

abstract:
  We provide a protocol to measure out-of-time-order correlation functions.
These correlation functions are of theoretical interest for diagnosing the
scrambling of quantum information in black holes and strongly interacting
quantum systems generally. Measuring them requires an echo-type sequence in
which the sign of a many-body Hamiltonian is reversed. We detail an
implementation employing cold atoms and cavity quantum electrodynamics to
realize the chaotic kicked top model, and we analyze effects of dissipation to
verify its feasibility with current technology. Finally, we propose in broad
strokes a number of other experimental platforms where similar
out-of-time-order correlation functions can be measured.


title:
Inhibiting Klein tunneling in graphene p-n junction without an external
  magnetic field

abstract:
  We study by first-principles calculations a densely packed island of organic
molecules (F4TCNQ) adsorbed on graphene. We find that with electron doping the
island naturally forms a p-n junction in the graphene sheet. For example, a
doping level of ~ 3 * 10^{13} electrons per cm^2 results in a p-n junction with
800 meV electrostatic potential barrier. Unlike in a conventional p-n junction
in graphene, in the case of the junction formed by an adsorbed organic
molecular island we expect that the Klein tunneling is inhibited, even without
an applied external magnetic field. Here Klein tunneling is inhibited by the
ferromagnetic order that spontaneously occurs in the molecular island upon
doping. We estimate that the magnetic barrier in the graphene sheet is around
10 mT.


title:
Periodic perturbations of unbounded Jacobi matrices I: Asymptotics of
  generalized eigenvectors

abstract:
  We study asymptotics of generalized eigenvectors associated with Jacobi
matrices. Under weak conditions on the coefficients we identify when the
matrices are self-adjoint and show that they satisfy strong non-subordinacy
condition.


title: Interlacing families and the Hermitian spectral norm of digraphs

abstract:
  It is proved that for any finite connected graph $G$, there exists an
orientation of $G$ such that the spectral radius of the corresponding Hermitian
adjacency matrix is smaller or equal to the spectral radius of the universal
cover of $G$ (with equality if and only if $G$ is a tree). This resolves a
problem proposed by Mohar. The proof uses the method of interlacing families of
polynomials that was developed by Marcus, Spielman, and Srivastava in their
seminal work on the existence of infinite families of Ramanujan graphs.


title:
Using magnetic levitation to produce cryogenic targets for inertial
  fusion energy: experiment and theory

abstract:
  We present experimental and theoretical studies of magnetic levitation of
hydrogen gas bubble surrounded by liquid hydrogen confined in a
semi-transparent spherical shell of 3 mm internal diameter. Such shells are
used as targets for the inertial confinement fusion (ICF), for which a
homogeneous (within a few percent) layer of a hydrogen isotope should be
deposited on the internal walls of the shells. The gravity does not allow the
hydrogen layer thickness to be homogeneous. To compensate this gravity effect,
we have used a non-homogeneous magnetic field created by a 10 T superconductive
solenoid. Our experiments show that the magnetic levitation homogenizes the
thickness of liquid hydrogen layer. However, the variation of the layer
thickness is very difficult to measure experimentally. Our theoretical model
allows the exact shape of the layer to be predicted. The model takes into
account the surface tension, gravity, van der Waals, and magnetic forces. The
numerical calculation shows that the homogeneity of the layer thickness is
satisfactory for the ICF purposes.


title: Semi-parametric Order-based Generalized Multivariate Regression

abstract:
  In this paper, we consider a generalized multivariate regression problem
where the responses are monotonic functions of linear transformations of
predictors. We propose a semi-parametric algorithm based on the ordering of the
responses which is invariant to the functional form of the transformation
function. We prove that our algorithm, which maximizes the rank correlation of
responses and linear transformations of predictors, is a consistent estimator
of the true coefficient matrix. We also identify the rate of convergence and
show that the squared estimation error decays with a rate of $o(1/\sqrt{n})$.
We then propose a greedy algorithm to maximize the highly non-smooth objective
function of our model and examine its performance through extensive
simulations. Finally, we compare our algorithm with traditional multivariate
regression algorithms over synthetic and real data.


title:
The Hydrogen Epoch of Reionization Array Dish II: Characterization of
  Spectral Structure with Electromagnetic Simulations and its science
  Implications

abstract:
  We use time-domain electromagnetic simulations to determine the spectral
characteristics of the Hydrogen Epoch of Reionization Arrays (HERA) antenna.
These simulations are part of a multi-faceted campaign to determine the
effectiveness of the dish's design for obtaining a detection of redshifted 21
cm emission from the epoch of reionization. Our simulations show the existence
of reflections between HERA's suspended feed and its parabolic dish reflector
that fall below -40 dB at 150 ns and, for reasonable impedance matches, have a
negligible impact on HERA's ability to constrain EoR parameters. It follows
that despite the reflections they introduce, dishes are effective for
increasing the sensitivity of EoR experiments at relatively low cost. We find
that electromagnetic resonances in the HERA feed's cylindrical skirt, which is
intended to reduce cross coupling and beam ellipticity, introduces significant
power at large delays ($-40$ dB at 200 ns) which can lead to some loss of
measurable Fourier modes and a modest reduction in sensitivity. Even in the
presence of this structure, we find that the spectral response of the antenna
is sufficiently smooth for delay filtering to contain foreground emission at
line-of-sight wave numbers below $k_\parallel \lesssim 0.2$ $h$Mpc$^{-1}$, in
the region where the current PAPER experiment operates. Incorporating these
results into a Fisher Matrix analysis, we find that the spectral structure
observed in our simulations has only a small effect on the tight constraints
HERA can achieve on parameters associated with the astrophysics of
reionization.


title: Broadband multimode fiber spectrometer

abstract:
  A general-purpose all-fiber spectrometer is demonstrated to overcome the
trade-off between spectral resolution and bandwidth. By integrating a
wavelength division multiplexer with five multimode optical fibers, we have
achieved 100 nm bandwidth with 0.03 nm resolution at wavelength 1500 nm. An
efficient algorithm is developed to reconstruct the spectrum from the speckle
pattern produced by interference of guided modes in the multimode fibers. Such
algorithm enables a rapid, accurate reconstruction of both sparse and dense
spectra in the presence of noise.


title: Pauli equation on noncommutative plane and the Seiberg-Witten map

abstract:
  We study the Pauli equation in noncommutative two dimensional plane which
exhibits the supersymmetry algebra when the gyro-magnetic ratio is $2$. The
significance of the Seiberg-Witten map in this context is discussed and its
effect in the problem is incorporated to all orders in $\theta$. We map the
noncommutative problem to an equivalent commutative problem by using a set of
generalised Bopp-shift transformations containing a scaling parameter. The
energy spectrum of the noncommutative Pauli Hamiltonian is obtained and found
to be $\theta$ corrected which is valid to all orders in $\theta$.


title:
Inferring supernova IIb/Ib/Ic ejecta properties from light curves and
  spectra: Correlations from radiative-transfer models

abstract:
  We present 1-D non-Local-Thermodynamic-Equilibrium time-dependent
radiative-transfer simulations for a large grid of supernovae (SNe) IIb/Ib/Ic
that result from the terminal explosion of the mass donor in a close-binary
system. Our sample covers ejecta masses $M_{\rm e}$ of 1.7$-$5.2M$_\odot$,
kinetic energies $E_{\rm kin}$ of 0.6$-$5.0$\times$10$^{51}$erg, and $^{56}$Ni
masses of 0.05$-$0.30M$_\odot$. We find a strong correlation between the
$^{56}$Ni mass and the photometric properties at maximum, and between the rise
time to bolometric maximum and the post-maximum decline rate. We confirm the
small scatter in ($V-R$) at 10d past $R$-band maximum. The quantity $V_{\rm m}
\equiv \sqrt{2E_{\rm kin}/M_{\rm e}}$ is comparable to the Doppler velocity
measured from HeI 5875\AA\ at maximum in SNe IIb/Ib, although some scatter
arises from the uncertain level of chemical mixing. The OI7772\AA\ line may be
used for SNe Ic, but the correspondence deteriorates with higher ejecta
mass/energy. We identify a temporal reversal of the Doppler velocity at maximum
absorption in the $\sim$1.05$\mu$m feature in all models. The reversal is due
to HeI alone and could serve as a test for the presence of helium in SNe Ic.
Because of variations in composition and ionisation, the ejecta opacity shows
substantial variations with both velocity and time. This is in part the origin
of the offset between our model light curves and the predictions from the
Arnett model.


title:
Julia sets for Fibonacci endomorphisms of $\mathbb{C}^2$ and
  $\mathbb{R}^2$

abstract:
  We study the dynamics of the family $f_c(x, y)= (xy+c, x)$ of endomorphisms
of $\mathbb{R}^2$ and $\mathbb{C}^2$, where $c$ is a real or complex parameter.
Such maps can be seen as perturbations of the map $f_0(x,y)=(xy,x)$, which is a
complexification of the Anosov torus map $(u,v) \mapsto (u+v,u)$.


title: Rigidity and a Riemann-Hilbert correspondence for p-adic local systems

abstract:
  We construct a functor from the category of p-adic etale local systems on a
smooth rigid analytic variety X over a p-adic field to the category of vector
bundles with an integrable connection over its "base change to B_dR", which can
be regarded as a first step towards the sought-after p-adic Riemann-Hilbert
correspondence. As a consequence, we obtain the following rigidity theorem for
p-adic local systems on a connected rigid analytic variety: if the stalk of
such a local system at one point, regarded as a p-adic Galois representation,
is de Rham in the sense of Fontaine, then the stalk at every point is de Rham.
Along the way, we also establish some basic properties of the p-adic Simpson
correspondence. Finally, we give an application of our results to Shimura
varieties.


title: Sorting With Forbidden Intermediates

abstract:
  A wide range of applications, most notably in comparative genomics, involve
the computation of a shortest sorting sequence of operations for a given
permutation, where the set of allowed operations is fixed beforehand. Such
sequences are useful for instance when reconstructing potential scenarios of
evolution between species, or when trying to assess their similarity. We
revisit those problems by adding a new constraint on the sequences to be
computed: they must \emph{avoid} a given set of \emph{forbidden intermediates},
which correspond to species that cannot exist because the mutations that would
be involved in their creation are lethal. We initiate this study by focusing on
the case where the only mutations that can occur are exchanges of any two
elements in the permutations, and give a polynomial time algorithm for solving
that problem when the permutation to sort is an involution.


title: Operational Theories of Physics as Categories

abstract:
  We introduce a new approach to the study of operational theories of physics
using category theory. We define a generalisation of the (causal)
operational-probabilistic theories of Chiribella et al. and establish their
correspondence with our new notion of an operational category. Our work is
based on effectus theory, a recently developed area of categorical logic, to
which we give an operational interpretation, demonstrating its relevance to the
modelling of general probabilistic theories.


title:
Surface and finite size effects impact of the phase diagrams, polar and
  dielectric properties of (Sr,Bi)Ta2O9 ferroelectric nanoparticles

abstract:
  In the framework of the thermodynamic approach Landau-Ginzburg-Devonshire
(LGD) combined with the equations of electrostatics, we investigated the effect
of polarization surface screening on finite size effects of the phase diagrams,
polar and dielectric properties of ferroelectric nanoparticles of different
shapes. We obtained and analyzed the analytical results for the dependences of
the ferroelectric phase transition temperature, critical size, spontaneous
polarization and thermodynamic coercive field on the shape and size of
nanoparticles. The pronounced size effect of these characteristics on the
scaling parameter, the ratio of the particle characteristic size to the length
of the surface screening, was revealed. Also our modeling predicts a
significant impact of the flexo-chemical effect (that is a joint action of
flexoelectric effect and chemical pressure) on the temperature of phase
transition, polar and dielectric properties of nanoparticles when their
chemical composition deviates from the stoichiometric one. We showed on the
example of the stoichiometric nanosized and fine SrBi2Ta2O9 particles that
except the vicinity of the critical size, where the system splitting into
domains has an important role, results of analytical calculation of the
spontaneous polarization have little difference from the numerical ones. We
revealed a strong impact of the flexo-chemical effect on the phase transition
temperature, polar and dielectric properties of SryBi2+xTa2O9 nanoparticles
when the ratio Sr/Bi deviates from the stoichiometric value of 0.5 from 0.35 to
0.65. From the analysis of experimental data we derived the parameters of the
theory, namely coefficients of expansion of the LGD functional, contribution of
flexo-chemical effect and the length of the surface screening.


title: Constraining white dwarf structure and neutrino physics in 47 Tucanae

abstract:
  We present a robust statistical analysis of the white dwarf cooling sequence
in 47 Tucanae. We combine HST UV and optical data in the core of the cluster,
Modules for Experiments in Stellar Evolution (MESA) white dwarf cooling models,
white dwarf atmosphere models, artificial star tests, and a Markov Chain Monte
Carlo (MCMC) sampling method to fit white dwarf cooling models to our data
directly. We use a technique known as the unbinned maximum likelihood to fit
these models to our data without binning. We use these data to constrain
neutrino production and the thickness of the hydrogen layer in these white
dwarfs. The data prefer thicker hydrogen layers $(q_\mathrm{H}=3.2\e{-5})$ and
we can strongly rule out thin layers $(q_\mathrm{H}=10^{-6})$. The neutrino
rates currently in the models are consistent with the data. This analysis does
not provide a constraint on the number of neutrino species.


title:
Global in time Strichartz inequalities on asymptotically flat manifolds
  with temperate trapping

abstract:
  We prove global Strichartz inequalities for the Schr\"odinger equation on a
large class of asymptotically conical manifolds. Letting $ P $ be the
nonnegative Laplace operator and $ f_0 \in C_0^{\infty}({\mathbb R}) $ be a
smooth cutoff equal to $1$ near zero, we show first that the low frequency part
of any solution $ e^{-itP} u_0 $, i.e. $ f_0 (P) e^{-itP} u_0 $, enjoys the
same global Strichartz estimates as on $ {\mathbb R}^n $ in dimension $ n \geq
3 $. We also show that the high energy part $ (1-f_0)(P) e^{-itP} u_0$ also
satisfies global Strichartz estimates without loss of derivatives outside a
compact set, even if the manifold has trapped geodesics but in a temperate
sense. We then show that the full solution $ e^{-itP}u_0 $ satisfies global
space-time Strichartz estimates if the trapped set is empty or sufficiently
filamentary, and we derive a scattering theory for the $ L^2 $ critical
nonlinear Schr\"odinger equation in this geometric framework.


title:
Some Approximation Results by $(p,q)$-analogue of Bernstein-Stancu
  Operators (Revised)

abstract:
  In this paper, we have given a corrigendum to our paper "Some Approximation
Results by $(p,q)$-analogue of Bernstein-Stancu Operators" published in Applied
Mathematics and Computation $264 (2015) 392-402.$ We introduce a new analogue
of Bernstein-Stancu operators and we call it as $(p,q)$-Bernstein-Stancu
operators. We study approximation properties based on Korovkin's type
approximation theorem of $(p,q)$-Bernstein-Stancu operators. We also establish
some direct theorems.


title: Learning to SMILE(S)

abstract:
  This paper shows how one can directly apply natural language processing (NLP)
methods to classification problems in cheminformatics. Connection between these
seemingly separate fields is shown by considering standard textual
representation of compound, SMILES. The problem of activity prediction against
a target protein is considered, which is a crucial part of computer aided drug
design process. Conducted experiments show that this way one can not only
outrank state of the art results of hand crafted representations but also gets
direct structural insights into the way decisions are made.


title: Induced Gravity II: Grand Unification

abstract:
  As an illustration of a renormalizable, asymptotically-free model of induced
gravity, we consider an $SO(10)$ gauge theory interacting with a real scalar
multiplet in the adjoint representation. We show that dimensional transmutation
can occur, spontaneously breaking $SO(10)$ to $SU(5){\otimes}U(1),$ while
inducing the Planck mass and a positive cosmological constant, all proportional
to the same scale $v$. All mass ratios are functions of the values of coupling
constants at that scale. Below this scale (at which the Big Bang may occur),
the model takes the usual form of Einstein-Hilbert gravity in de Sitter space
plus calculable corrections. We show that there exist regions of parameter
space in which the breaking results in a local minimum of the effective action,
and a {\bf positive} dilaton $(\hbox{mass})^2$ from two-loop corrections
associated with the conformal anomaly. Furthermore, unlike the singlet case we
considered previously, some minima lie within the basin of attraction of the
ultraviolet fixed point. Moreover, the asymptotic behavior of the coupling
constants also lie within the range of convergence of the Euclidean path
integral, so there is hope that there will be candidates for sensible vacua.
Although open questions remain concerning unitarity of all such renormalizable
models of gravity, it is not obvious that, in curved backgrounds such as those
considered here, unitarity is violated. In any case, any violation that may
remain will be suppressed by inverse powers of the reduced Planck mass.


title: Contextual LSTM (CLSTM) models for Large scale NLP tasks

abstract:
  Documents exhibit sequential structure at multiple levels of abstraction
(e.g., sentences, paragraphs, sections). These abstractions constitute a
natural hierarchy for representing the context in which to infer the meaning of
words and larger fragments of text. In this paper, we present CLSTM (Contextual
LSTM), an extension of the recurrent neural network LSTM (Long-Short Term
Memory) model, where we incorporate contextual features (e.g., topics) into the
model. We evaluate CLSTM on three specific NLP tasks: word prediction, next
sentence selection, and sentence topic prediction. Results from experiments run
on two corpora, English documents in Wikipedia and a subset of articles from a
recent snapshot of English Google News, indicate that using both words and
topics as features improves performance of the CLSTM models over baseline LSTM
models for these tasks. For example on the next sentence selection task, we get
relative accuracy improvements of 21% for the Wikipedia dataset and 18% for the
Google News dataset. This clearly demonstrates the significant benefit of using
context appropriately in natural language (NL) tasks. This has implications for
a wide variety of NL applications like question answering, sentence completion,
paraphrase generation, and next utterance prediction in dialog systems.


title: Random walk in the low disorder ballistic regime

abstract:
  We consider a random walk in $\mathbb Z^d$ which jumps from a site $x$ to a
nearest neighboring site $x+e$ (where $e\in V:=\{x\in\mathbb Z^d: |x|_1=1\}$)
with probability $p_0(e)+\epsilon\xi(x,e)$. Here $\sum_e p_0(e)=1$, $p_0(e)>
0$, $\epsilon$ is a small parameter while $\{\{\xi (x,e):e\in V\}: x\in\mathbb
Z^d\}$ are i.i.d. random variables with an absolute value bounded by $1$. We
review recent progress in the non-vanishing velocity case, giving an asymptotic
expansion in $\epsilon$ of the invariant measure of the environmental process,
and bounds for the velocity.


title:
Relation between Lacunarity, Correlation dimension and Euclidean
  dimension of Systems

abstract:
  Lacunarity is a measure often used to quantify the lack of translational
invariance present in fractals and multifractal systems. The generalised
dimensions, specially the first three, are also often used to describe various
aspects of mass distribution in such systems. In this work we establish that
the graph (\textit{lacunarity curve}) depicting the variation of lacunarity
with scaling size, is non-linear in multifractal systems. We propose a
generalised relation between the Euclidean dimension, the Correlation Dimension
and the lacunarity of a system that lacks translational invariance, through the
slope of the lacunarity curve. Starting from the basic definitions of these
measures and using statistical mechanics, we track the standard algorithms- the
box counting algorithm for the determination of the generalised dimensions, and
the gliding box algorithm for lacunarity, to establish this relation. We go on
to validate the relation on six systems, three of which are deterministically
determined, while three others are real. Our examples span 2- and 3-
dimensional systems, and euclidean, monofractal and multifractal geometries. We
first determine the lacunarity of these systems using the gliding box
algorithm. In each of the six cases studied, the euclidean dimension, the
correlation dimension in case of multifractals, and the lacunarity of the
system, together, yield a value of the slope $S$ of the lacunarity curve at any
length scale. The predicted $S$ value matches the slope as determined from the
actual plot of the lacunarity curves at the corresponding length scales. This
establishes that the relation holds for systems of any geometry or dimension.


title: Stacking for machine learning redshifts applied to SDSS galaxies

abstract:
  We present an analysis of a general machine learning technique called
'stacking' for the estimation of photometric redshifts. Stacking techniques can
feed the photometric redshift estimate, as output by a base algorithm, back
into the same algorithm as an additional input feature in a subsequent learning
round. We shown how all tested base algorithms benefit from at least one
additional stacking round (or layer). To demonstrate the benefit of stacking,
we apply the method to both unsupervised machine learning techniques based on
self-organising maps (SOMs), and supervised machine learning methods based on
decision trees. We explore a range of stacking architectures, such as the
number of layers and the number of base learners per layer. Finally we explore
the effectiveness of stacking even when using a successful algorithm such as
AdaBoost. We observe a significant improvement of between 1.9% and 21% on all
computed metrics when stacking is applied to weak learners (such as SOMs and
decision trees). When applied to strong learning algorithms (such as AdaBoost)
the ratio of improvement shrinks, but still remains positive and is between
0.4% and 2.5% for the explored metrics and comes at almost no additional
computational cost.


title: Solar energy production: Short-term forecasting and risk management

abstract:
  Electricity production via solar energy is tackled via short-term forecasts
and risk management. Our main tool is a new setting on time series. It allows
the definition of "confidence bands" where the Gaussian assumption, which is
not satisfied by our concrete data, may be abandoned. Those bands are quite
convenient and easily implementable. Numerous computer simulations are
presented.


title:
Using Close White Dwarf + M Dwarf Stellar Pairs to Constrain the Flare
  Rates in Close Stellar Binaries

abstract:
  We present a study of the statistical flare rates of M dwarfs (dMs) with
close white dwarf (WD) companions (WD+dM; typical separations < 1 au). Our
previous analysis demonstrated that dMs with close WD companions are more
magnetically active than their field counterparts. One likely implication of
having a close binary companion is increased stellar rotation through
disk-disruption, tidal effects, and/or angular momentum exchange; increased
stellar rotation has long been associated with an increase in stellar activity.
Previous studies show a strong correlation between dMs that are magnetically
active (showing H{\alpha} in emission) and the frequency of stellar flare
rates. We examine the difference between the flare rates observed in close
WD+dM binary systems and field dMs. Our sample consists of a subset of 181
close WD+dM pairs from Morgan et al. (2012) observed in the Sloan Digital Sky
Survey Stripe 82, where we obtain multi-epoch observations in the Sloan
ugriz-bands. We find an increase in the overall flaring fraction in the close
WD+dM pairs (0.09$\pm$0.03%) compared to the field dMs (0.0108$\pm$0.0007%;
Kowalski et al. 2009) and a lower flaring fraction for active WD+dMs
(0.05$\pm$0.03%) compared to active dMs (0.28$\pm$0.05%; Kowalski et al. 2009).
We discuss how our results constrain both the single and binary dM flare rates.
Our results also constrain dM multiplicity, our knowledge of the Galactic
transient background, and may be important for the habitability of attending
planets around dMs with close companions.


title:
Physical properties of galaxies: toward a consistent comparison between
  hydrodynamical simulations and SDSS

abstract:
  We study the effects of applying observational techniques to derive the
properties of simulated galaxies, with the aim of making an unbiased comparison
between observations and simulations. For our study, we used fifteen galaxies
simulated in a cosmological context using three different feedback and chemical
enrichment models, and compared their z=0 properties with data from the Sloan
Digital Sky Survey (SDSS). We show that the physical properties obtained
directly from the simulations without post-processing can be very different to
those obtained mimicking observational techniques. In order to provide
simulators a way to reliably compare their galaxies with SDSS data, for each
physical property that we studied - colours, magnitudes, gas and stellar
metallicities, mean stellar ages and star formation rates - we give scaling
relations that can be easily applied to the values extracted from the
simulations. These scalings have in general a high correlation, except for the
galaxy mean stellar ages and gas oxygen metallicities. Our simulated galaxies
are photometrically similar to galaxies in the blue cloud/green valley, but in
general they appear older, passive and with lower metal content compared to
most of the spirals in SDSS. As a careful assessment of the
agreement/disagreement with observations is the primary test of the baryonic
physics implemented in hydrodynamical codes, our study shows that considering
the observational biases in the derivation of the galaxies' properties is of
fundamental importance to decide on the failure/success of a galaxy formation
model.


title:
Theory of edge-state optical absorption in two-dimensional transition
  metal dichalcogenide flakes

abstract:
  We develop an analytical model to describe sub-bandgap optical absorption in
two-dimensional semiconducting transition metal dichalcogenide (s-TMD)
nanoflakes. The material system represents an array of few-layer molybdenum
disulfide crystals, randomly orientated in a polymer matrix. We propose that
optical absorption involves direct transitions between electronic edge-states
and bulk-bands, depends strongly on the carrier population, and is saturable
with sufficient fluence. For excitation energies above half the bandgap, the
excess energy is absorbed by the edge-state electrons, elevating their
effective temperature. Our analytical expressions for the linear and nonlinear
absorption could prove useful tools in the design of practical photonic devices
based on s-TMDs.


title:
The 2 Ms Chandra Deep Field-North Survey and the 250 ks Extended Chandra
  Deep Field-South Survey: Improved Point-Source Catalogs

abstract:
  We present improved point-source catalogs for the 2 Ms Chandra Deep
Field-North (CDF-N) and the 250 ks Extended Chandra Deep Field-South (E-CDF-S),
implementing a number of recent improvements in Chandra source-cataloging
methodology. For the CDF-N/E-CDF-S, we provide a main catalog that contains
683/1003 X-ray sources detected with wavdetect at a false-positive probability
threshold of $10^{-5}$ that also satisfy a binomial-probability
source-selection criterion of $P<0.004$/$P<0.002$. Such an approach maximizes
the number of reliable sources detected: a total of 196/275 main-catalog
sources are new compared to the Alexander et al. (2003) CDF-N/Lehmer et al.
(2005) E-CDF-S main catalogs. We also provide CDF-N/E-CDF-S supplementary
catalogs that consist of 72/56 sources detected at the same wavdetect threshold
and having $P$ of $0.004-0.1$/$0.002-0.1$ and $K_s\le22.9/K_s\le22.3$ mag
counterparts. For all $\approx1800$ CDF-N and E-CDF-S sources, including the
$\approx500$ newly detected ones (these being generally fainter and more
obscured), we determine X-ray source positions utilizing centroid and
matched-filter techniques; we also provide multiwavelength identifications,
apparent magnitudes of counterparts, spectroscopic and/or photometric
redshifts, basic source classifications, and estimates of observed AGN and
galaxy source densities around respective field centers. Simulations show that
both the CDF-N and E-CDF-S main catalogs are highly reliable and reasonably
complete. Background and sensitivity analyses indicate that the on-axis mean
flux limits reached represent a factor of $\approx1.5-2.0$ improvement over the
previous CDF-N and E-CDF-S limits. We make our data products publicly
available.


title:
Exact Analytic Solution for Non-Linear Density Fluctuation in a LCDM
  Universe

abstract:
  We derive the exact third-order analytic solution of the matter density
fluctuation in the proper-time hypersurface in a $\Lambda$CDM universe,
accounting for the explicit time-dependence and clarifying the relation to the
initial condition. Furthermore, we compare our analytic solution to the
previous calculation in the comoving gauge, and to the standard Newtonian
perturbation theory by providing Fourier kernels for the relativistic effects.
Our results provide an essential ingredient for a complete description of
galaxy bias in the relativistic context.


title:
Interpreting the Recent Upper Limit on the Gravitational Wave Background
  from the Parkes Pulsar Timing Array

abstract:
  We provide comments on the article by Shannon et al. (Sep 2015) entitled
"Gravitational waves from binary supermassive black holes missing in pulsar
observations". The purpose of this letter is to address several misconceptions
of the public and other scientists regarding the conclusions of that work.


title: Modeling Reionization in a Bursty Universe

abstract:
  We present semi-analytic models of the epoch of reionization focusing on the
differences between continuous and bursty star formation (SF). Our model
utilizes physically motivated analytic fits to 1D radiative transfer
simulations of HII regions around dark matter halos in a representative cosmic
volume. Constraining our simulations with observed and extrapolated UV
luminosity functions of high redshift galaxies, we find that for a fixed halo
mass, stellar populations forming in bursty models produce larger HII regions
which leave behind long-lived relic HII regions which are able to maintain
partial ionization in the intergalactic medium (IGM) in a manner similar to an
early X-ray background. The overall effect is a significant increase in the
optical depth of the IGM, $\tau_e$, and a milder increase of the redshift of
reionization. To produce $\tau_e =0.066$ observed by Planck and complete
reionization by redshift $z_{\rm re}\sim 6$, models with bursty SF require an
escape fraction $f_{\rm esc}\sim 2\%-10\%$ that is 2-10 times lower than
$f_{\rm esc}\sim 17\%$ found assuming continuous SF and is consistent with
upper limits on $f_{\rm esc}$ from observations at $z=0$ and $z\sim 1.3-6$. The
ionizing photon budget needed to reproduce the observed $\tau_e$ and $z_{\rm
re}$ depends on the period and duty cycle of the bursts of SF and the
temperature of the neutral IGM. These results suggest that the tension between
observed and predicted ionizing photon budget for reionization can be
alleviated if reionization is driven by short bursts of SF, perhaps relating to
the formation of Population~III stars and compact star clusters such as
proto-globular clusters.


title: Calabi-Yau Threefolds With Small Hodge Numbers

abstract:
  We present a list of Calabi-Yau threefolds known to us, and with holonomy
groups that are precisely SU(3), rather than a subgroup, with small Hodge
numbers, which we understand to be those manifolds with height
$(h^{1,1}+h^{2,1})\le 24$. With the completion of a project to compute the
Hodge numbers of free quotients of complete intersection Calabi-Yau threefolds,
most of which were computed in Refs. [1-3] and the remainder in Ref. [4], many
new points have been added to the tip of the Hodge plot, updating the reviews
by Davies and Candelas in Refs. [1, 5]. In view of this and other recent
constructions of Calabi-Yau threefolds with small height, we have produced an
updated list.


title:
A Method to improve line flux and redshift measurements with narrowband
  filters

abstract:
  High redshift star-forming galaxies are discovered routinely through a flux
excess in narrowband filters (NB) caused by an emission line. In most cases,
the width of such filters is broad compared to typical line widths, and the
throughput of the filters varies substantially within the bandpass. This leads
to substantial uncertainties in redshifts and fluxes that are derived from the
observations with one specific NB. In this work we demonstrate that the
uncertainty in measured line parameters can be sharply reduced by using
repeated observations of the same target field with filters that have slightly
different transmittance curves. Such data are routinely collected with some
large field imaging cameras that use multiple detectors and a separate filter
for each of the detectors. An example is the NB118 data from ESO's VISTA
InfraRed CAMera (VIRCAM). We carefully developed and characterized this method
to determine more accurate redshift and line flux estimates from the ratio of
apparent fluxes measured from observations in different narrowband filters and
several matching broadband filters. Then, we tested the obtainable quality of
parameter estimation both on simulated and actual observations for the example
of Ha in the VIRCAM NB118 filters combined with broadband data in Y, J, H. We
find that by using this method, the errors in the measured lines fluxes can be
reduced up to almost an order of magnitude and that an accuracy in wavelength
of better than 1nm can be achieved with the ~13nm wide NB118 filters.


title:
The Need for Laboratory Work to Aid in The Understanding of Exoplanetary
  Atmospheres

abstract:
  Advancements in our understanding of exoplanetary atmospheres, from massive
gas giants down to rocky worlds, depend on the constructive challenges between
observations and models. We are now on a clear trajectory for improvements in
exoplanet observations that will revolutionize our ability to characterize the
atmospheric structure, composition, and circulation of these worlds. These
improvements stem from significant investments in new missions and facilities,
such as JWST and the several planned ground-based extremely large telescopes.
However, while exoplanet science currently has a wide range of sophisticated
models that can be applied to the tide of forthcoming observations, the
trajectory for preparing these models for the upcoming observational challenges
is unclear. Thus, our ability to maximize the insights gained from the next
generation of observatories is not certain. In many cases, uncertainties in a
path towards model advancement stems from insufficiencies in the laboratory
data that serve as critical inputs to atmospheric physical and chemical tools.
We outline a number of areas where laboratory or ab initio investigations could
fill critical gaps in our ability to model exoplanet atmospheric opacities,
clouds, and chemistry. Specifically highlighted are needs for: (1) molecular
opacity linelists with parameters for a diversity of broadening gases, (2)
extended databases for collision-induced absorption and dimer opacities, (3)
high spectral resolution opacity data for relevant molecular species, (4)
laboratory studies of haze and condensate formation and optical properties, (5)
significantly expanded databases of chemical reaction rates, and (6)
measurements of gas photo-absorption cross sections at high temperatures. We
hope that by meeting these needs, we can make the next two decades of exoplanet
science as productive and insightful as the previous two decades. (abr)


title:
Cosmic Voids in the SDSS DR12 BOSS Galaxy Sample: The Alcock-Paczynski
  Test

abstract:
  We apply the Alcock-Paczynski (AP) test to the stacked voids identified using
the large-scale structure galaxy catalog from the Baryon Oscillation
Spectroscopic Survey (BOSS). This galaxy catalog is part of the Sloan Digital
Sky Survey (SDSS) Data Release 12 and is the final catalog of SDSS-III. We also
use 1000 mock galaxy catalogs that match the geometry, density, and clustering
properties of the BOSS sample in order to characterize the statistical
uncertainties of our measurements and take into account systematic errors such
as redshift space distortions. For both BOSS data and mock catalogs, we use the
ZOBOV algorithm to identify voids, we stack together all voids with effective
radii of 30-100Mpc/h in the redshift range 0.43-0.7, and we accurately measure
the shape of the stacked voids. Our tests with the mock catalogs show that we
measure the stacked void ellipticity with a statistical precision of 2.6%. We
find that the stacked voids in redshift space are slightly squashed along the
line of sight, which is consistent with previous studies. We repeat this
measurement of stacked void shape in the BOSS data assuming several values of
Omega_m within the flat LCDM model, and we compare to the mock catalogs in
redshift space in order to perform the AP test. We obtain a constraint of
$\Omega_m = 0.38^{+0.18}_{-0.15}$ at the 68% confidence level from the AP test.
We discuss the various sources of statistical and systematic noise that affect
the constraining power of this method. In particular, we find that the measured
ellipticity of stacked voids scales more weakly with cosmology than the
standard AP prediction, leading to significantly weaker constraints. We discuss
how AP constraints will improve in future surveys with larger volumes and
densities.


title: (p,q)-Beta Functions and Applications in Approximation

abstract:
  In the present paper, we consider (p,q)-analogue of the Beta operators and
using it, we propose the integral modification of the generalized Bernstein
polynomials. We estimate some direct results on local and global approximation.
Also, we illustrate some graphs for the convergence of
(p,q)-Bernstein-Durrmeyer operators for different values of the parameters p
and q using Mathematica package.


title: Approximation by (p,q)-Baskakov-Beta operators

abstract:
  In the present paper, we consider $(p,q)$-analogue of the Baskakov-Beta
operators and using it, we estimate some direct results on approximation. Also,
we represent the convergence of these operators graphically using MATLAB.


title: Revised analysis of $^{40}$Ca+$^{96}$Zr fusion reactions

abstract:
  Fusion data for $^{40}$Ca+$^{96}$Zr are analyzed by coupled-channels
calculations that are based on a standard Woods-Saxon potential and include
couplings to multiphonon excitations and transfer channels. The couplings to
multiphonon excitations are the same as used in a previous work. The transfer
couplings are calibrated to reproduce the measured neutron transfer data. This
type of calculation gives a poor fit to the fusion data. However, by
multiplying the transfer couplings with a $\sqrt{2}$ one obtains an excellent
fit. The scaling of the transfer strengths is supposed to simulate the combined
effect of neutron and proton transfer, and the calculated one- and two-nucleon
transfer cross sections are indeed in reasonable agreement with the measured
cross sections.


title: Modelling the Evolution of Ly$\alpha$ Blobs and Ly$\alpha$ Emitters

abstract:
  In this work we model the observed evolution in comoving number density of
Lyman-alpha blobs (LABs) as a function of redshift, and try to find which
mechanism of emission is dominant in LAB. Our model calculates LAB emission
both from cooling radiation from the intergalactic gas accreting onto galaxies
and from star formation (SF). We have used dark matter (DM) cosmological
simulation to which we applied empirical recipes for Ly$\alpha$ emission
produced by cooling radiation and SF in every halo. In difference to the
previous work, the simulated volume in the DM simulation is large enough to
produce an average LABs number density. At a range of redshifts $z\sim 1-7$ we
compare our results with the observed luminosity functions of LABs and LAEs.
Our cooling radiation luminosities appeared to be too small to explain LAB
luminosities at all redshifts. In contrast, for SF we obtained a good agreement
with observed LFs at all redshifts studied. We also discuss uncertainties which
could influence the obtained results, and how LAB LFs could be related to each
other in fields with different density.


title: Heat transport study of field-tuned quantum criticality in CeIrIn5

abstract:
  The in-plane electrical resistivity, rho, and thermal conductivity, kappa, of
the heavy-fermion superconductor CeIrIn5 were measured down to 40mK in magnetic
fields up to 11 T applied along the c axis. For all fields above Hc2=4T of
filamentary superconductivity, we find that the ratio of heat and charge
conductivities in the T to 0 limit obeys the Wiedemann-Franz law,
kappa/T=L0/rho, where L0 = 2.45*10^-8 WOhmK^-2 is the Sommerfeld value of the
Lorenz number. The temperature-dependent parts of both the electrical and
thermal resistivity,w = T/L0 kappa, follow the functional dependence expected
for the Fermi liquid theory of metals with rho - rho_0 = AT^2, w - w_0 = BT^2,
with rho0 = w0 and B ~ 2A. The coefficient B does not show a significant field
dependence even upon approaching Hc2 = 0.4 T of the bulk superconducting state.
The weak response to the magnetic field is in stark contrast with the behavior
found in the closely related CeCoIn5, in which the field-tuned quantum critical
point coincides with Hc2. The value of the electron-electron mass enhancement,
as judged by the A and B coefficients, is about one order of magnitude reduced
in CeIrIn5 as compared to CeCoIn5 (in spite of the fact that the zero field
gamma_0 in CeIrIn5 is twice as large as gamma_0 in CeCoIn5), which suggests
that the material is significantly farther away from the magnetic quantum
critical point at bulk Hc2 and at all of the studied fields. A suppressed
Kadowaki-Woods ratio in CeIrIn5 compared to CeCoIn5 suggests a notably more
localized nature of f electrons in the compound.


title: (p, q)-Sz\'asz-Mirakyan-Baskakov-Stancu type Operators

abstract:
  This deals with the Stancu variant of (p, q)-Sz\'asz-Mirakyan-Baskakov
operators. Estimation of moments and establishing few basic approximation
results which comprise weighted approximation and direct estimates in view of
modulus of continuity is the aim of this paper. Steklov mean method has been
used for linear approximation. For the particular case {\alpha} = 0, \b{eta} =
0, we get (p, q) -Sz\'asz-Mirakyan-Baskakov operators.


title: Many-body interferometry of a Rydberg-dressed spin lattice

abstract:
  Ultracold atoms are an ideal platform to study strongly correlated phases of
matter in and out of equilibrium. Much of the experimental progress in this
field crucially relies on the control of the contact interaction between two
atoms. Control of strong long-range interactions between distant ground state
atoms has remained a long standing goal, opening the path towards the study of
fundamentally new quantum many-body systems including frustrated or topological
magnets and supersolids. Optical dressing of ground state atoms by
near-resonant laser coupling to Rydberg states has been proposed as a versatile
method to engineer such interactions. However, up to now the great potential of
this approach for interaction control in a many-body setting has eluded
experimental confirmation. Here we report the realisation of coherent
Rydberg-dressing in an ultracold atomic lattice gas and directly probe the
induced interaction potential using an interferometric technique with single
atom sensitivity. We use this approach to implement a two-dimensional synthetic
spin lattice and demonstrate its versatility by tuning the range and anisotropy
of the effective spin interactions. Our measurements are in remarkable
agreement with exact solutions of the many-body dynamics, providing further
evidence for the high degree of accurate interaction control in these systems.
Finally, we identify a collective many-body decay process, and discuss possible
routes to overcome this current limitation of coherence times. Our work marks
the first step towards the use of laser-controlled Rydberg interactions for the
study of exotic quantum magnets in optical lattices.


title:
The Emergence of Negative Superhumps in Cataclysmic Variables: Smoothed
  Particle Hydrodynamics Simulations

abstract:
  Negative superhumps are believed to arise in cataclysmic variable systems
when the accretion disk is tilted with respect to the orbital plane. Slow
retrograde precession of the line-of-nodes results in a signal---the negative
superhump---with a period slightly less than the orbital period. Previous
studies have shown that tilted disks exhibit negative superhumps, but a
consensus on how a disk initially tilts has not been reached. Analytical work
by Lai suggests that a magnetic field on the primary can lead to a tilt
instability in a disk when the dipole moment is offset in angle from the spin
axis of the primary and when the primary's spin axis is, itself, not aligned
with the angular momentum axis of the binary orbit. However, Lai did not apply
his work to the formation of negative superhumps. In this paper, we add Lai's
model to an existing smoothed particle hydrodynamics code. Using this code, we
demonstrate the emergence of negative superhumps in the "light curve" for a
range of magnetic dipole moments. We show that the period deficits calculated
from these negative superhumps match those in simulations using manually tilted
disks. When positive superhumps appear ($q \lesssim 0.33$), we show that the
period excesses calculated from these signals are also consistent with previous
results. Using examples, we show that the disks are tilted, though the tilt
varies periodically, and that they precess in the retrograde direction. The
magnetic fields found to lead to the emergence of negative superhumps lie in
the kilogauss regime.


title: Bivariate-Schurer-Stancu operators based on (p;q)-integers

abstract:
  The aim of this article is to introduce a bivariate extension of
Shurer-Stancu operators based on (p q)integers. We prove uniform approximation
by means of Bohman Korovkin type theorem rate of convergence using total
modulus of smoothness and degree of approximation by using second order modulus
of smoothness Peetres K functional Lipschitz type class.


title:
Model-based clustering with data correction for removing artifacts in
  gene expression data

abstract:
  The NIH Library of Integrated Network-based Cellular Signatures (LINCS)
contains gene expression data from over a million experiments, using Luminex
Bead technology. Only 500 colors are used to measure the expression levels of
the 1,000 landmark genes measured, and the data for the resulting pairs of
genes are deconvolved. The raw data are sometimes inadequate for reliable
deconvolution leading to artifacts in the final processed data. These include
the expression levels of paired genes being flipped or given the same value,
and clusters of values that are not at the true expression level. We propose a
new method called model-based clustering with data correction (MCDC) that is
able to identify and correct these three kinds of artifacts simultaneously. We
show that MCDC improves the resulting gene expression data in terms of
agreement with external baselines, as well as improving results from subsequent
analysis.


title:
Statistical modeling of isoform splicing dynamics from RNA-seq time
  series data

abstract:
  Isoform quantification is an important goal of RNA-seq experiments, yet it
remains prob- lematic for genes with low expression or several isoforms. These
difficulties may in principle be ameliorated by exploiting correlated
experimental designs, such as time series or dosage response experiments. Time
series RNA-seq experiments, in particular, are becoming in- creasingly popular,
yet there are no methods that explicitly leverage the experimental design to
improve isoform quantification. Here we present DICEseq, the first isoform
quantification method tailored to correlated RNA-seq experiments. DICEseq
explicitly models the corre- lations between different RNA-seq experiments to
aid the quantification of isoforms across experiments. Numerical experiments on
simulated data sets show that DICEseq yields more accurate results than
state-of-the-art methods, an advantage that can become considerable at low
coverage levels. On real data sets, our results show that DICEseq provides
substan- tially more reproducible and robust quantifications, increasing the
correlation of estimates from replicate data sets by up to 10% on genes with
low or moderate expression levels (bot- tom third of all genes). Furthermore,
DICEseq permits to quantify the trade-off between temporal sampling of RNA and
depth of sequencing, frequently an important choice when planning experiments.
Our results have strong implications for the design of RNA-seq ex- periments,
and offer a novel tool for improved analysis of such data sets. Python code is
freely available at http://diceseq.sf.net.


title: A unified framework for spline estimators

abstract:
  This article develops a unified framework to study the asymptotic properties
of all periodic spline-based estimators, that is, of regression, penalized and
smoothing splines. The explicit form of the periodic Demmler-Reinsch basis in
terms of exponential splines allows the derivation of an expression for the
asymptotic equivalent kernel on the real line for all spline estimators
simultaneously. The corresponding bandwidth, which drives the asymptotic
behavior of spline estimators, is shown to be a function of the number of knots
and the smoothing parameter. Strategies for the selection of the optimal
bandwidth and other model parameters are discussed.


title:
On approximation by Stancu type q-Bernstein-Schurer-Kantorovich
  operators

abstract:
  In this paper we introduce the Stancu type generalization of the
q-Bernstein-Schurer-Kantorovich operators and examine their approximation
properties. We investigate the convergence of our operators with the help of
the Korovkin's approximation theorem and examine the convergence of these
operators in the Lipschitz class of functions. We also investigate the
approximation process for these operators through the statistical Korovkin's
approximation theorem. Also, we present some direct theorems for these
operators. Finally we introduce the bivariate analogue of these operators and
study some results for the bivariate case.


title: Some equations with features of digit reversal and powers

abstract:
  In this paper we consider integers in base 10 like $abc$, where $a$, $b$, $c$
are digits of the integer, such that $abc^2 - (abc \cdot cba) \; = \; \pm n^2$,
where $n$ is a positive integer, as well as equations $abc^2 - (abc \cdot cba)
\; = \; \pm n^3$, and $abc^3 - (abc \cdot cba) \; = \; \pm n^2$ We consider
asymptotic density of solutions. We also compare the results with ones with
bases different from 10.


title:
The First Detection of Photometric Variability in a Y Dwarf: WISE
  J140518.39+553421.3

abstract:
  We present the first detection of photometric variability of a
spectroscopically-confirmed Y dwarf. The Infrared Array Camera on board the
Spitzer Space Telescope was used to obtain times series photometry at 3.6 and
4.5 microns over a twenty four hour period at two different epochs separated by
149 days. Variability is evident at 4.5 um in the first epoch and at 3.6 and
4.5 um in the second epoch which suggests that the underlying cause or causes
of this variability change on the timescales of months. The second-epoch [3.6]
and [4.5] light curves are nearly sinusoidal in form, in phase, have periods of
roughly 8.5 hours, and have semi-amplitudes of 3.5%. We find that a simple
geometric spot model with a single bright spot reproduces these observations
well. We also compare our measured semi-amplitudes of the second epoch light
curves to predictions of the static, one-dimensional, partly cloudy and hot
spot models of Morley and collaborators and find that neither set of models can
reproduce the observed [3.6] and[4.5] semi-amplitudes simultaneously. More
advanced two- or three-dimensional models that include time-dependent phenomena
like vertical mixing, cloud formation, and thermal relaxation are therefore
sorely needed in order to properly interpret our observations.


title:
Analysis of random walks in dynamic random environments via
  $L^2$-perturbations

abstract:
  We consider random walks in dynamic random environments given by Markovian
dynamics on $\mathbb{Z}^d$. We assume that the environment has a stationary
distribution $\mu$ and satisfies the Poincar\'e inequality w.r.t. $\mu$. The
random walk is a perturbation of another random walk (called "unperturbed"). We
assume that also the environment viewed from the unperturbed random walk has
stationary distribution $\mu$. Both perturbed and unperturbed random walks can
depend heavily on the environment and are not assumed to be finite-range. We
derive a law of large numbers, an averaged invariance principle for the
position of the walker and a series expansion for the asymptotic speed. We also
provide a condition for non-degeneracy of the diffusion, and describe in some
details equilibrium and convergence properties of the environment seen by the
walker. All these results are based on a more general perturbative analysis of
operators that we derive in the context of $L^2$-bounded perturbations of
Markov processes by means of the so-called Dyson-Phillips expansion.


title: On Planar Valued CSPs

abstract:
  We study the computational complexity of planar valued constraint
satisfaction problems (VCSPs), which require the incidence graph of the
instance be planar. First, we show that intractable Boolean VCSPs have to be
self-complementary to be tractable in the planar setting, thus extending a
corresponding result of Dvorak and Kupec [ICALP'15] from CSPs to VCSPs. Second,
we give a complete complexity classification of conservative planar VCSPs on
arbitrary finite domains. In this case planarity does not lead to any new
tractable cases and thus our classification is a sharpening of the
classification of conservative VCSPs by Kolmogorov and Zivny [JACM'13].


title:
A New Model For Incorporating the Variations of the Dielectric
  Permittivity of the Medium: Part (1)Potential Distribution of an Electrical
  Double Layer in Rectangular Nano channel by Applying Finite Element Method
  Technique

abstract:
  The effect of the dielectric permittivity of the electrolytic medium in the
Electrical Double Layer (EDL) in Nanochannel is an important factor that
requires a correction, before the application of the model in various chemical
and biomedical examinations. However very few efforts are put forth to
accommodate this into the mathematics of the EDL Models developed hitherto,
even though it was realized by a host of authors for the past half a century or
even more. Most of the Nanoc hannel made lab-on-chips in a rectangular cross
section require suitable impregnation of this. The effect of the EDL in a
nanochannel isimportant in various chemical and biomedical examinations. Most
of the nanochannelmadelab on chips in a rectangular cross section. The EDL
insuch a nanochannel is governed by two dimensional Gouy Chapman (GC)equation.


title:
On the inclusion of the diagonal Born-Oppenheimer correction in surface
  hopping methods

abstract:
  The diagonal Born-Oppenheimer correction (DBOC) stems from the diagonal
second derivative coupling term in the adiabatic representation, and it can
have an arbitrary large magnitude when a gap between neighbouring
Born-Oppenheimer (BO) potential energy surfaces (PESs) is closing.
Nevertheless, DBOC is typically neglected in mixed quantum-classical methods of
simulating nonadiabatic dynamics (e.g., fewest-switch surface hopping (FSSH)
method). A straightforward addition of DBOC to BO PESs in the FSSH method,
FSSH+D, has been shown to lead to numerically much inferior results for models
containing conical intersections. More sophisticated variation of the DBOC
inclusion, phase-space surface-hopping (PSSH) was more successful than FSSH+D
but on model problems without conical intersections. This work comprehensively
assesses the role of DBOC in nonadiabatic dynamics of two electronic state
problems and the performance of FSSH, FSSH+D, and PSSH methods in variety of
one- and two-dimensional models. Our results show that the inclusion of DBOC
can enhance the accuracy of surface hopping simulations when two conditions are
simultaneously satisfied: 1) nuclei have kinetic energy lower than DBOC and 2)
PESs are not strongly nonadiabatically coupled. The inclusion of DBOC is
detrimental in situations where its energy scale becomes very high or even
diverges, because in these regions PESs are also very strongly coupled. In this
case, the true quantum formalism heavily relies on an interplay between
diagonal and off-diagonal nonadiabatic couplings while surface hopping
approaches treat diagonal terms as PESs and off-diagonal ones stochastically.


title: Exactly Energy Conserving Semi-Implicit Particle in Cell Formulation

abstract:
  We report a new particle in cell (PIC) method based on the semi-implicit
approach. The novelty of the new method is that unlike any of its semi-implicit
predecessors at the same time retains the explicit computational cycle and
conserves energy exactly. Recent research has presented fully implicit methods
where energy conservation is obtained as part of a non linear iteration
procedure. The new method (referred to as Energy Conserving Semi-Implicit
Method, ECSIM), instead, does not require any non-linear iteration and its
computational cycle is similar to that of explicit PIC.
  The properties of the new method are: i) it conserves energy exactly to
round-off for any time step or grid spacing; ii) it is unconditionally stable
in time, freeing the user from the need to resolve the electron plasma
frequency and allowing the user to select any desired time step; iii) it
eliminates the constraint of the finite grid instability, allowing the user to
select any desired resolution without being forced to resolve the Debye length;
iv) the particle mover has a computational complexity identical to that of the
explicit PIC, only the field solver has an increased computational cost.
  The new ECSIM is tested in a number of benchmarks where accuracy and
computational performance are tested.


title:
Erratum: Progenitor-explosion connection and remnant birth masses for
  neutrino-driven supernovae of iron-core progenitors (2012, ApJ, 757, 69)

abstract:
  An erroneous interpretation of the hydrodynamical results led to an incorrect
determination of the fallback masses in Ugliano et al. (2012), which also (on a
smaller level) affects the neutron star masses provided in that paper. This
problem was already addressed and corrected in the follow-up works by Ertl et
al. (2015) and Sukhbold et al. (2015). Therefore, the reader is advised to use
the new data of the latter two publications. In the remaining text of this
Erratum we present the differences of the old and new fallback results in
detail and explain the origin of the mistake in the original analysis by
Ugliano et al. (2012).


title: On Davenport and Heilbronn-Type of Functions

abstract:
  A correction is brought to the opinion expressed in a previous note published
in this journal that the off critical line points indicated by some authors as
being non trivial zeros of the Davenport and Heilbronn function are affected of
approximation errors and illustrations are presented which enforce the
conclusion that they are true zeros. It is shown also that linear combinations
of L-functions satisfying the same Riemann-type of functional equation do not
offer counterexamples to RH, contrary to a largely accepted position.


title: A non-equilibrium extension of quantum gravity

abstract:
  A variety of quantum gravity models (including spin foams) can be described
using a path integral formulation. A path integral has a well-known statistical
mechanical interpretation in connection with a canonical ensemble. In this
sense, a path integral describes the thermodynamic equilibrium of a local
system in a thermal bath. This interpretation is in contrast to solutions of
Einstein's Equations which depart from local thermodynamical equilibrium (one
example is shown explicitly). For this reason, we examine an extension of the
path integral model to a (locally) non-equilibrium description. As a
non-equilibrium description, we propose to use a global microcanonical ensemble
with constraints. The constraints reduce the set of admissible microscopic
states to be consistent with the macroscopic geometry. We also analyse the
relation between the microcanonical description and a statistical approach not
based on dynamical assumptions which has been proposed recently. This analysis
is of interest for the test of consistency of the non-equilibrium description
with general relativity and quantum field theory.


title:
Zeros of Lattice Sums: 2. A Geometry for the Generalised Riemann
  Hypothesis

abstract:
  The location of zeros of the basic double sum over the square lattice is
studied. This sum can be represented in terms of the product of the Riemann
zeta function and the Dirichlet beta function, so that the assertion that all
its non-trivial zeros lie on the critical line is a particular case of the
Generalised Riemann Hypothesis (GRH). It is shown that a new necessary and
sufficient condition for this special case of the GRH to hold is that a
particular set of equimodular and equiargument contours of a ratio of MacDonald
function double sums intersect only on the critical line. It is further shown
that these contours could only intersect off the critical line on the boundary
of discrete regions of the complex plane called "inner islands". Numerical
investigations are described related to this geometrical condition, and it is
shown that for the first ten thousand zeros of both the zeta function and the
beta function over 70\% of zeros lie outside the inner islands, and thus would
be guaranteed to lie on the critical line by the arguments presented here. A
new sufficient condition for the Riemann Hypothesis to hold is also presented.


title: Lorentz Invariant Vacuum Solutions in General Relativity

abstract:
  All Lorentz invariant solutions of vacuum Einstein's equations are found. It
is proved that these solutions describe space-times of constant curvature.


title: Conformal frames in cosmology

abstract:
  From higher dimensional theories, e.g. string theory, one expects the
presence of non-minimally coupled scalar fields. We review the notion of
conformal frames in cosmology and emphasize their physical equivalence, which
holds at least at a classical level.
  Furthermore, if there is a field, or fields, which dominates the universe, as
it is often the case in cosmology, we can use such notion of frames to treat
our system, matter and gravity, as two different sectors. On one hand, the
gravity sector which describes the dynamics of the geometry and on the other
hand the matter sector which has such geometry as a playground. We use this
interpretation to build a model where the fact that a curvaton couples to a
particular frame metric could leave an imprint in the CMB.


title:
Fredholm integral equations of the first kind and topological
  information theory

abstract:
  The Fredholm integral equations of the first kind are a classical example of
ill-posed problem in the sense of Hadamard. If the integral operator is
self-adjoint and admits a set of eigenfunctions, then a formal solution can be
written in terms of eigenfunction expansions. One of the possible methods of
regularization consists in truncating this formal expansion after restricting
the class of admissible solutions through a-priori global bounds. In this paper
we reconsider various possible methods of truncation from the viewpoint of the
$\varepsilon$-coverings of compact sets.

categories: math.NA cs.IT math-ph math.CA math.IT math.MP


title: 2-States and a fifth force

abstract:
  We consider a formulation using Kerr-Newman metric which leads to an extra
force hitherto unknown and we justify that this is the "fifth Force" that is
being sought after.


title:
A Machine Learning Approach to Forecasting Remotely Sensed Vegetation
  Health

abstract:
  Drought threatens food and water security around the world, and this threat
is likely to become more severe under climate change. High resolution
predictive information can help farmers, water managers, and others to manage
the effects of drought. We have created an open source tool to produce
short-term forecasts of vegetation health at high spatial resolution, using
data that are global in coverage. The tool automates downloading and processing
Moderate Resolution Imaging Spectroradiometer (MODIS) datasets, and training
gradient-boosted machine models on hundreds of millions of observations to
predict future values of the Enhanced Vegetation Index. We compared the
predictive power of different sets of variables (raw spectral MODIS data and
Level-3 MODIS products) in two regions with distinct agro-ecological systems,
climates, and cloud coverage: Sri Lanka and California. Our tool provides
considerably greater predictive power on held-out datasets than simpler
baseline models.


title: Complete mapping of the spin-wave spectrum in vortex state nano-disk

abstract:
  We report a study on the complete spin-wave spectrum inside a vortex state
nano-disk. Transformation of this spectrum is continuously monitored as the
nano-disk becomes gradually magnetized by a perpendicular magnetic field and
encouters a second order phase transition to the uniformly magnetized state.
This reveals the bijective relationship that exists between the eigen-modes in
the vortex state with the ones in the saturated state. It is found that the
gyrotropic mode can be continuously viewed as a uniform phase precession, which
uniquely softens (its frequency vanishes) at the saturation field to transform
above into the Kittel mode. By contrast the other spin-wave modes remain finite
as a function of the applied field while their character is altered by level
anti-crossing.


title:
Line Shapes Emitted from Spiral Structures around Symmetric Orbits of
  Supermassive Binary Black Holes

abstract:
  Variability of active galactic nuclei is not well understood. One possible
explanation is existence of supermassive binary black holes (SMBBH) in their
centres. It is expected that major mergers are common in the Universe. It is
expected that each supermassive black hole of every galaxy eventually finish as
a SMBBH system in the core of newly formed galaxy. Here we model the emission
line profiles of active galactic nuclei (AGN) assuming that the flux and
emission line shapes variation are induced by supermassive binary black hole
systems (SMBBH). We assume that accreting gas inside of circumbinary (CB) disk
is photo ionized by mini accretion disk emission around each SMBBH. We
calculate variations of emission line flux, shifts and shapes for different
parameters of SMBBH orbits. We consider cases with different masses and
inclinations for circular orbits and measure the effect to the shape of
emission line profiles and flux variability.


title: Left-orderable Computable Groups

abstract:
  We answer a question of Downey and Kurtz on left-orderable groups by showing
that there is a computable left-orderable group which is not classically
isomorphic to a computable group with a computable left-order.


title: Congruences on Direct Products of Transformation and Matrix Monoids

abstract:
  Malcev described the congruences of the monoid $T_n$ of all full
transformations on a finite set $X_n=\{1, \dots,n\}$. Since then, congruences
have been characterized in various other monoids of (partial) transformations
on $X_n$, such as the symmetric inverse monoid $In_n$ of all injective partial
transformations, or the monoid $PT_n$ of all partial transformations.
  The first aim of this paper is to describe the congruences of the direct
products $Q_m\times P_n$, where $Q$ and $P$ belong to $\{T, PT,In\}$.
  Malcev also provided a similar description of the congruences on the
multiplicative monoid $F_n$ of all $n\times n$ matrices with entries in a field
$F$, our second aim is provide a description of the principal congruences of
$F_m \times F_n$.
  The paper finishes with some comments on the congruences of products of more
than two transformation semigroups, and a fairly large number of open problems.


title:
Temperature and Electric Field Induced Metal-Insulator Transition in
  Atomic Layer Deposited Vanadium Dioxide Thin Films

abstract:
  Amorphous vanadium dioxide (VO$_{2}$) films deposited by atomic layer
deposition (ALD) were crystallized with an ex situ anneal at 660-670 ${\deg}$C
for 1-2 hours under a low oxygen pressure (10$^{-4}$ to 10$^{-5}$ Torr). Under
these conditions the crystalline VO$_{2}$ phase was maintained, while formation
of the V$_{2}$O$_{5}$ phase was suppressed. Electrical transition from the
insulator to the metallic phase was observed in the 37-60 ${\deg}$C range, with
a R$_{ON}$/R$_{OFF}$ ratio of up to about 750 and critical transition
temperature of 7-10 ${\deg}$C. Electric field applied across two-terminal
device structures induced a reversible phase change, with a room temperature
transition field of about 25 kV/cm in the VO$_{2}$ sample processed with the 2
hr long anneal. Both the width and slope of the field induced MIT hysteresis
were dependent upon the VO$_{2}$ crystalline quality.


title: Sticking of molecules on non-porous amorphous water ice

abstract:
  Accurate modeling of physical and chemical processes in the interstellar
medium requires detailed knowledge of how atoms and molecule adsorb on dust
grains. However, the sticking coefficient, a number between 0 and 1 that
measures the first step in the interaction of a particle with a surface, is
usually assumed in simulations of ISM environments to be either 0.5 or 1. Here
we report on the determination of the sticking coefficient of H$_2$, D$_2$,
N$_2$, O$_2$, CO, CH$_4$, and CO$_2$ on non-porous amorphous solid water
(np-ASW). The sticking coefficient was measured over a wide range of surface
temperatures using a highly collimated molecular beam. We showed that the
standard way of measuring the sticking coefficient --- the King-Wells method
--- leads to the underestimation of trapping events in which there is
incomplete energy accommodation of the molecule on the surface. Surface
scattering experiments with the use of a pulsed molecular beam are used instead
to measure the sticking coefficient. Based on the values of the measured
sticking coefficient we suggest a useful general formula of the sticking
coefficient as a function of grain temperature and molecule-surface binding
energy. We use this formula in a simulation of ISM gas-grain chemistry to find
the effect of sticking on the abundance of key molecules both on grains and in
the gas-phase.


title: Data Assimilation and Sampling in Banach spaces

abstract:
  This paper studies the problem of approximating a function $f$ in a Banach
space $X$ from measurements $l_j(f)$, $j=1,\dots,m$, where the $l_j$ are linear
functionals from $X^*$. Most results study this problem for classical Banach
spaces $X$ such as the $L_p$ spaces, $1\le p\le \infty$, and for $K$ the unit
ball of a smoothness space in $X$. Our interest in this paper is in the model
classes $K=K(\epsilon,V)$, with $\epsilon>0$ and $V$ a finite dimensional
subspace of $X$, which consists of all $f\in X$ such that $dist(f,V)_X\le
\epsilon$. These model classes, called {\it approximation sets}, arise
naturally in application domains such as parametric partial differential
equations, uncertainty quantification, and signal processing.
  A general theory for the recovery of approximation sets in a Banach space is
given. This theory includes tight a priori bounds on optimal performance, and
algorithms for finding near optimal approximations. We show how the recovery
problem for approximation sets is connected with well-studied concepts in
Banach space theory such as liftings and the angle between spaces. Examples are
given that show how this theory can be used to recover several recent results
on sampling and data assimilation.


title:
HectoMAP and Horizon Run 4: Dense Structures and Voids in the Real and
  Simulated Universe

abstract:
  HectoMAP is a dense redshift survey of red galaxies covering a 53 $deg^{2}$
strip of the northern sky. HectoMAP is 97\% complete for galaxies with
$r<20.5$, $(g-r)>1.0$, and $(r-i)>0.5$. The survey enables tests of the
physical properties of large-scale structure at intermediate redshift against
cosmological models. We use the Horizon Run 4, one of the densest and largest
cosmological simulations based on the standard $\Lambda$ Cold Dark Matter
($\Lambda$CDM) model, to compare the physical properties of observed
large-scale structures with simulated ones in a volume-limited sample covering
8$\times10^6$ $h^{-3}$ Mpc$^3$ in the redshift range $0.22<z<0.44$. We apply
the same criteria to the observations and simulations to identify over- and
under-dense large-scale features of the galaxy distribution. The richness and
size distributions of observed over-dense structures agree well with the
simulated ones. Observations and simulations also agree for the volume and size
distributions of under-dense structures, voids. The properties of the largest
over-dense structure and the largest void in HectoMAP are well within the
distributions for the largest structures drawn from 300 Horizon Run 4 mock
surveys. Overall the size, richness and volume distributions of observed
large-scale structures in the redshift range $0.22<z<0.44$ are remarkably
consistent with predictions of the standard $\Lambda$CDM model.


title:
High-order time stepping for the Navier-Stokes equations with minimal
  computational complexity

abstract:
  In this paper we present extensions of the schemes proposed in \cite{GM14}
that lead to a decoupling of the velocity components in the momentum equation.
The new schemes reduce the solution of the incompressible Navier-Stokes
equations to a set of classical uncoupled parabolic problems for each Cartesian
component of the velocity. The pressure is explicitly recovered after the
velocity is computed.


title:
Molecular Level-Crossing and the Geometric Phase Effect from the Optical
  Hanle Perspective

abstract:
  Level-crossing spectroscopy involves lifting the degeneracy of an excited
state and using the interference of two nearly degenerate levels to measure the
excited state lifetime. Here we use the idea of interference between different
pathways to study the momentum-dependent wave packet lifetime due an excited
state level-crossing (conical intersection) in a molecule. Changes in
population from the wave packet propagation are reflected in the detected
fluorescence. We use a chirped pulse to control the wave packet momentum.
Changing the chirp rate affects the transition to the lower state through the
conical intersection. It also affects the interference of different pathways in
the upper electronic state, due to the geometric phase acquired. Increasing the
chirp rate decreases the coherence of the wave packet in the upper electronic
state. This suggests that there is a finite momentum dependent lifetime of the
wave packet through the level-crossing as function of chirp. We dub this
lifetime the wave packet momentum lifetime.


title:
Policy Error Bounds for Model-Based Reinforcement Learning with Factored
  Linear Models

abstract:
  In this paper we study a model-based approach to calculating approximately
optimal policies in Markovian Decision Processes. In particular, we derive
novel bounds on the loss of using a policy derived from a factored linear
model, a class of models which generalize numerous previous models out of those
that come with strong computational guarantees. For the first time in the
literature, we derive performance bounds for model-based techniques where the
model inaccuracy is measured in weighted norms. Moreover, our bounds show a
decreased sensitivity to the discount factor and, unlike similar bounds derived
for other approaches, they are insensitive to measure mismatch. Similarly to
previous works, our proofs are also based on contraction arguments, but with
the main differences that we use carefully constructed norms building on Banach
lattices, and the contraction property is only assumed for operators acting on
"compressed" spaces, thus weakening previous assumptions, while strengthening
previous results.


title: Distributed Constraint Optimization Problems and Applications: A Survey

abstract:
  The field of Multi-Agent System (MAS) is an active area of research within
Artificial Intelligence, with an increasingly important impact in industrial
and other real-world applications. Within a MAS, autonomous agents interact to
pursue personal interests and/or to achieve common objectives. Distributed
Constraint Optimization Problems (DCOPs) have emerged as one of the prominent
agent architectures to govern the agents' autonomous behavior, where both
algorithms and communication models are driven by the structure of the specific
problem. During the last decade, several extensions to the DCOP model have
enabled them to support MAS in complex, real-time, and uncertain environments.
This survey aims at providing an overview of the DCOP model, giving a
classification of its multiple extensions and addressing both resolution
methods and applications that find a natural mapping within each class of
DCOPs. The proposed classification suggests several future perspectives for
DCOP extensions, and identifies challenges in the design of efficient
resolution algorithms, possibly through the adaptation of strategies from
different areas.


title:
Axon Membrane Skeleton Structure is Optimized for Coordinated Sodium
  Propagation

abstract:
  Axons transmit action potentials with high fidelity and minimal jitter. This
unique capability is likely the result of the spatiotemporal arrangement of
sodium channels along the axon. Super-resolution microscopy recently revealed
that the axon membrane skeleton is structured as a series of actin rings
connected by spectrin filaments that are held under entropic tension. Sodium
channels also exhibit a periodic distribution pattern, as they bind to ankyrin
G, which associates with spectrin. Here, we elucidate the relationship between
the axon membrane skeleton structure and the function of the axon. By combining
cytoskeletal dynamics and continuum diffusion modeling, we show that spectrin
filaments under tension minimize the thermal fluctuations of sodium channels
and prevent overlap of neighboring channel trajectories. Importantly, this axon
skeletal arrangement allows for a highly reproducible band-like activation of
sodium channels leading to coordinated sodium propagation along the axon.


title: The Segmented iHMM: A Simple, Efficient Hierarchical Infinite HMM

abstract:
  We propose the segmented iHMM (siHMM), a hierarchical infinite hidden Markov
model (iHMM) that supports a simple, efficient inference scheme. The siHMM is
well suited to segmentation problems, where the goal is to identify points at
which a time series transitions from one relatively stable regime to a new
regime. Conventional iHMMs often struggle with such problems, since they have
no mechanism for distinguishing between high- and low-level dynamics.
Hierarchical HMMs (HHMMs) can do better, but they require much more complex and
expensive inference algorithms. The siHMM retains the simplicity and efficiency
of the iHMM, but outperforms it on a variety of segmentation problems,
achieving performance that matches or exceeds that of a more complicated HHMM.