title:
Near-Infrared Spectroscopy of Faint Discrete X-ray Point Sources
  Constituting the Galactic Ridge X-ray Emission

abstract:
  The Galactic Ridge X-ray Emission (GRXE) is apparently extended X-ray
emission along the Galactic Plane. The X-ray spectrum is characterized by hard
continuum with a strong Fe K emission feature in the 6-7 keV band. A
substantial fraction (~80%) of the GRXE in the Fe band was resolved into point
sources by deep Chandra imaging observations, thus GRXE is mostly composed of
dim Galactic X-ray point sources at least in this energy band. To investigate
the populations of these dim X-ray point sources, we carried out Near-Infrared
(NIR) follow-up spectroscopic observations in two deep Chandra fields located
in the Galactic plane at (l,b)=(0.1{\arcdeg}, -1.4{\arcdeg}) and
(28.5{\arcdeg}, 0.0{\arcdeg}) using NTT/SofI and Subaru/MOIRCS. We obtained
well-exposed NIR spectra from 65 objects and found that there are three main
classes of Galactic sources based on the X-ray color and NIR spectral features:
those having (A) hard X-ray spectra and NIR emission features such as
HI(Br{\gamma}), HeI, and HeII (2 objects), (B) soft X-ray spectra and NIR
absorption features such as HI, NaI, CaI, and CO (46 objects), and (C) hard
X-ray spectra and NIR absorption features such as HI, NaI, CaI and CO (17
objects). From these features, we argue that class A sources are Cataclysmic
Variables (CVs), and class B sources are late-type stars with enhanced coronal
activity, which is in agreement with current knowledge. Class C sources
possibly belong to a new group of objects, which has been poorly studied so
far. We argue that the candidate sources for class C are the binary systems
hosting white dwarfs and late-type companions with very low accretion rates. It
is likely that this newly recognized class of the sources contribute to a
non-negligible fraction of the GRXE, especially in the Fe K band.


title:
Josephson effect in topological superconducting rings coupled to a
  microwave cavity

abstract:
  We theoretically study a one dimensional p-wave superconducting mesoscopic
ring interrupted by a weak link and coupled inductively to a microwave cavity.
We establish an input-output description for the cavity field in the presence
of the ring, and identify the electronic contributions to the cavity response
and their dependence on various parameters, such as the magnetic flux, chemical
potential, and cavity frequency. We show that the cavity response is $4\pi$
periodic as a function of the magnetic flux in the topological region, stemming
from the so called fractional Josephson current carried by the Majorana
fermions, while it is $2\pi$ periodic in the non-topological phase, consistent
with the normal Josephson effect. We find a strong dependence of the signal on
the cavity frequency, as well as on the parity of the ground state. Our model
takes into account fully the interplay between the low-energy Majorana modes
and the gaped bulks states, which we show is crucial for visualizing the
evolution of the Josephson effect during the transition from the topological to
the trivial phase.


title: Long-Term Average Cost in Featured Transition Systems

abstract:
  A software product line is a family of software products that share a common
set of mandatory features and whose individual products are differentiated by
their variable (optional or alternative) features. Family-based analysis of
software product lines takes as input a single model of a complete product line
and analyzes all its products at the same time. As the number of products in a
software product line may be large, this is generally preferable to analyzing
each product on its own. Family-based analysis, however, requires that standard
algorithms be adapted to accomodate variability.
  In this paper we adapt the standard algorithm for computing limit average
cost of a weighted transition system to software product lines. Limit average
is a useful and popular measure for the long-term average behavior of a quality
attribute such as performance or energy consumption, but has hitherto not been
available for family-based analysis of software product lines. Our algorithm
operates on weighted featured transition systems, at a symbolic level, and
computes limit average cost for all products in a software product line at the
same time. We have implemented the algorithm and evaluated it on several
examples.


title: A quantitative obstruction to collapsing surfaces

abstract:
  We provide a quantitative obstruction to collapsing surfaces of genus at
least 2 under a lower curvature bound and an upper diameter bound. Keywords:
curvature; diameter; volume; filling radius; systole; Gromov-Hausdorff distance


title: PyPanda: a Python Package for Gene Regulatory Network Reconstruction

abstract:
  PANDA (Passing Attributes between Networks for Data Assimilation) is a gene
regulatory network inference method that uses message-passing to integrate
multiple sources of 'omics data. PANDA was originally coded in C++. In this
application note we describe PyPanda, the Python version of PANDA. PyPanda runs
considerably faster than the C++ version and includes additional features for
network analysis. Availability: The open source PyPanda Python package is
freely available at https://github.com/davidvi/pypanda. Contact: d.g.p.van
ijzendoorn@lumc.nl


title:
Validation of SPAMM Tagged MRI Based Measurement of 3D Soft Tissue
  Deformation

abstract:
  This study presents and validates a novel (non-ECG-triggered) MRI sequence
based on SPAtial Modulation of the Magnetization (SPAMM) to non-invasively
measure 3D (quasi-static) soft tissue deformations using only six acquisitions
(three static and three indentations). In current SPAMM tagged MRI approaches
data is typically constructed from many repeated motion cycles. This has so far
restricted its application to the measurement of highly repeatable and periodic
movements (e.g. cardiac deformation). In biomechanical applications where soft
tissue deformation is artificially induced, often by indentation, significant
repeatability constraints exist and, for clinical applications, discomfort and
health issues generally preclude a large number of repetitions.


title:
Rank-Deficient Solutions for Optimal Signaling over Wiretap MIMO
  Channels

abstract:
  Capacity-achieving signaling strategies for the Gaussian wiretap MIMO channel
are investigated without the degradedness assumption. In addition to known
solutions, a number of new rank-deficient solutions for the optimal transmit
covariance matrix are obtained. The case of a weak eavesdropper is considered
in detail and the optimal covariance is established in an explicit, closed form
with no extra assumptions. This provides lower and upper bounds to the secrecy
capacity in the general case with a bounded gap, which are tight for a weak
eavesdropper or/and low SNR. Closed form solutions are also obtained for
isotropic and omnidirectional eavesdroppers, based on which lower and upper
bounds to the secrecy capacity are established in the general case. Sufficient
and necessary conditions for optimality of 3 popular transmission techniques,
namely the zero-forcing (ZF), the standard water-filling (WF) over the channel
eigenmodes and the isotropic signaling (IS), are established for the MIMO
wiretap channel. These solutions are appealing due to their lower complexity.
In particular, no wiretap codes are needed for the ZF transmission, and no
precoding or feedback is needed for the isotropic signaling.


title: Spectral determinants and quantum theta functions

abstract:
  It has been recently conjectured that the spectral determinants of operators
associated to mirror curves can be expressed in terms of a generalization of
theta functions, called quantum theta functions. In this paper we study the
symplectic properties of these spectral determinants by expanding them around
the point hbar=2pi, where the quantum theta functions become conventional theta
functions. We find that they are modular invariant, order by order, and we give
explicit expressions for the very first terms of the expansion. Our derivation
requires a detailed understanding of the modular properties of topological
string free energies in the Nekrasov-Shatashvili limit. We derive these
properties in a diagrammatic form. Finally, we use our results to provide a new
test of the duality between topological strings and spectral theory.


title: Utilitarian Distributed Constraint Optimization Problems

abstract:
  Privacy has been a major motivation for distributed problem optimization.
However, even though several methods have been proposed to evaluate it, none of
them is widely used. The Distributed Constraint Optimization Problem (DCOP) is
a fundamental model used to approach various families of distributed problems.
As privacy loss does not occur when a solution is accepted, but when it is
proposed, privacy requirements cannot be interpreted as a criteria of the
objective function of the DCOP. Here we approach the problem by letting both
the optimized costs found in DCOPs and the privacy requirements guide the
agents' exploration of the search space. We introduce Utilitarian Distributed
Constraint Optimization Problem (UDCOP) where the costs and the privacy
requirements are used as parameters to a heuristic modifying the search
process. Common stochastic algorithms for decentralized constraint optimization
problems are evaluated here according to how well they preserve privacy.
Further, we propose some extensions where these solvers modify their search
process to take into account their privacy requirements, succeeding in
significantly reducing their privacy loss without significant degradation of
the solution quality.


title:
Digital image correlation and finite element modelling as a method to
  determine mechanical properties of human soft tissue in vivo

abstract:
  The mechanical properties of human soft tissue are crucial for impact
biomechanics, rehabilitation engineering and surgical simulation. Validation of
these constitutive models using human data remains challenging and often
requires the use of non-invasive imaging and inverse finite element (FE)
analysis. Post processing data from imaging methods such as tagged magnetic
resonance imaging (MRI) can be challenging. Digital Image Correlation (DIC)
however is a relatively straightforward imaging method and thus the goal of
this study was to assess the use of DIC in combination with FE modelling to
determine the bulk material properties of human soft tissue. Indentation
experiments were performed on a silicone gel soft tissue phantom. A two camera
DIC setup was then used to record the 3D surface deformation. The experiment
was then simulated using a FE model.


title: Convergence of the Yamabe flow on manifolds with minimal boundary

abstract:
  We study the Yamabe flow on compact Riemannian manifolds of dimensions
greater than two with minimal boundary. Convergence to a metric with constant
scalar curvature and minimal boundary is established in dimensions up to seven,
and in any dimensions if the manifold is spin.


title:
DisCSPs with Privacy Recast as Planning Problems for Utility-based
  Agents

abstract:
  Privacy has traditionally been a major motivation for decentralized problem
solving. However, even though several metrics have been proposed to quantify
it, none of them is easily integrated with common solvers. Constraint
programming is a fundamental paradigm used to approach various families of
problems. We introduce Utilitarian Distributed Constraint Satisfaction Problems
(UDisCSP) where the utility of each state is estimated as the difference
between the the expected rewards for agreements on assignments for shared
variables, and the expected cost of privacy loss. Therefore, a traditional
DisCSP with privacy requirements is viewed as a planning problem. The actions
available to agents are: communication and local inference. Common
decentralized solvers are evaluated here from the point of view of their
interpretation as greedy planners. Further, we investigate some simple
extensions where these solvers start taking into account the utility function.
In these extensions we assume that the planning problem is further restricting
the set of communication actions to only the communication primitives present
in the corresponding solver protocols. The solvers obtained for the new type of
problems propose the action (communication/inference) to be performed in each
situation, defining thereby the policy.


title: On the harmonic and geometric maximal operators

abstract:
  We examine the harmonic and geometric maximal operators defined for a general
basis of open sets in $\R^n$. We prove two weight norm inequalities for the
harmonic maximal operator assuming testing conditions over characteristic
functions of unions of sets from the basis. We also prove a that a bumped two
weight $A_p$-like condition is sufficient for the two weight boundedness of the
harmonic maximal operator.


title:
Collier: a fortran-based Complex One-Loop LIbrary in Extended
  Regularizations

abstract:
  We present the library Collier for the numerical evaluation of one-loop
scalar and tensor integrals in perturbative relativistic quantum field
theories. The code provides numerical results for arbitrary tensor and scalar
integrals for scattering processes in general quantum field theories. For
tensor integrals either the coefficients in a covariant decomposition or the
tensor components themselves are provided. Collier supports complex masses,
which are needed in calculations involving unstable particles. Ultraviolet and
infrared singularities are treated in dimensional regularization. For soft and
collinear singularities mass regularization is available as an alternative.


title:
Multiband behavior and non-metallic low-temperature state of
  K$_{0.50}$Na$_{0.24}$Fe$_{1.52}$Se$_{2}$

abstract:
  We report evidence for multiband transport and an insulating low-temperature
normal state in superconducting K$_{0.50}$Na$_{0.24}$Fe$_{1.52}$Se$_{2}$ with
$T_{c}\approx 20$ K. The temperature-dependent upper critical field, $H_{c2}$,
is well described by a two-band BCS model. The normal-state resistance,
accessible at low temperatures only in pulsed magnetic fields, shows an
insulating logarithmic temperature dependence as $T \rightarrow 0$ after
superconductivity is suppressed. This is similar as for high-$T_{c}$ copper
oxides and granular type-I superconductors, suggesting that the
superconductor-insulator transition observed in high magnetic fields is related
to intrinsic nanoscale phase separation.


title: Cyclic extensions are radical

abstract: We show that finite Galois extensions with cyclic Galois group are radical.


title: TMRT Observations of Carbon-chain molecules in Serpens South 1A

abstract:
  We report Shanghai Tian Ma Radio Telescope detections of several long
carbon-chain molecules at C and Ku band, including HC3N, HC5N, HC7N, HC9N, C3S,
C6H and C8H toward the starless cloud Serpens South 1a. We detected some
transitions (HC9N J=13-12 F=12-11 and F=14-13, H13CCCN J=2-1 F=1-0 and F=1-1,
HC13CCN J=2-1 F=2-2, F=1-0 and F=1-1, HCC13CN J=2-1 F=1-0 and F=1-1) and
resolved some hyperfine components (HC5N J=6-5 F=5-4, H13CCCN J=2-1 F=2-1) for
the first time in the interstellar medium. The column densities of these
carbon-chain molecules in a range of 10^{12}-10^{13} cm^{-2} are comparable to
two carbon-chain molecule rich sources, TMC-1 and Lupus-1A. The abundance
ratios are 1.00:(1.11\pm0.15):(1.47\pm0.18) for [H13CCCN]:[HC13CCN]:[HCC13CN].
This result implies that the 13C isotope is also concentrated in the carbon
atom adjacent to the nitrogen atom in HC3N in Serpens south 1a, which is
similar to TMC-1. The [HC3N]/[H13CCCN] ratio of 78\pm9, the [HC3N]/[HC13CCN]
ratio of 70\pm8, and the [HC3N]/[HCC13CN] ratio of 53\pm4 are also comparable
to those in TMC-1. In any case, Serpens South 1a proves a testing ground for
understanding carbon-chain chemistry.


title:
Optical characterization of red blood cells from individuals with sickle
  cell trait and disease in Tanzania using quantitative phase imaging

abstract:
  Sickle cell disease (SCD) is common across Sub-Saharan Africa. However, the
investigation of SCD in this area has been significantly limited mainly due to
the lack of research facilities and skilled personnel. Here, we present optical
measurements of individual red blood cells (RBCs) from healthy individuals and
individuals with SCD and sickle cell trait in Tanzania using the quantitative
phase imaging technique. By employing a quantitative phase imaging unit (QPIU),
an existing microscope in a clinic is transformed into a powerful quantitative
phase microscope providing measurements on the morphological, biochemical, and
biomechanical properties of individual cells. The present approach will open up
new opportunities for cost-effective investigation and diagnosis of several
diseases in low resource environments.


title: Surface chemistry in photodissociation regions

abstract:
  The presence of dust can strongly affect the chemical composition of the
interstellar medium. We model the chemistry in photodissociation regions (PDRs)
using both gas-phase and dust-phase chemical reactions. Our aim is to determine
the chemical compositions of the interstellar medium (gas/dust/ice) in regions
with distinct (molecular) gas densities that are exposed to radiation fields
with different intensities. We have significantly improved the Meijerink PDR
code by including 3050 new gas-phase chemical reactions and also by
implementing surface chemistry. In particular, we have included 117 chemical
reactions occurring on grain surfaces covering different processes, such as
adsorption, thermal desorption, chemical desorption, two-body reactions, photo
processes, and cosmic-ray processes on dust grains. We obtain abundances for
different gas and solid species as a function of visual extinction, depending
on the density and radiation field. We also analyse the rates of the formation
of CO2 and H2O ices in different environments. In addition, we study how
chemistry is affected by the presence/absence of ice mantles (bare dust or icy
dust) and the impact of considering different desorption probabilities. The
type of substrate (bare dust or icy dust) and the probability of desorption can
significantly alter the chemistry occurring on grain surfaces, leading to
differences of several orders of magnitude in the abundances of gas-phase
species, such as CO, H2CO, and CH3OH. The type of substrate, together with the
density and intensity of the radiation field, also determine the threshold
extinction to form ices of CO2 and H2O. We also conclude that H2CO and CH3OH
are mainly released into the gas phase of low, far-ultraviolet illuminated PDRs
through chemical desorption upon two-body surface reactions, rather than
through photodesorption.


title: Some symmetry properties of four-dimensional Walker manifolds

abstract:
  In this paper, we investigate geometric properties of some curvature tensors
of a four-dimensional Walker manifold. Some characterization theorems are also
obtained.


title: Directly Observing the Galaxies Likely Responsible for Reionization

abstract:
  We report a new analysis of the Hubble Frontier Fields clusters Abell 2744
and MACS 0416 using wavelet decomposition to remove the cluster light, enabling
the detection of highly magnified (>50x) galaxies a factor of 10x fainter in
luminosity than previous studies. We find 167 galaxies at z > 6, and with this
sample we are able to characterize the UV luminosity function to M_UV = -12.5
at z ~ 6, -14 at z ~ 7 and -15 at z ~ 8. We find a steep faint-end slope (alpha
<-2), and with our improved statistics at the faint end we reduce the
fractional uncertainty on alpha to <2% at z ~ 6 - 7 and 4% at z ~ 8. We also
investigate the systematic uncertainty due to the lens modelling by using every
available lens model individually and comparing the results; this systematic
fractional uncertainty on alpha is <4% at all redshifts. We now directly
observe galaxies in the luminosity regime where simulations predict a change in
the faint-end slope of the luminosity function, yet our results provide
statistically very strong evidence against any turnover in the luminosity range
probed, more consistent with simulations in which stars form in lower-mass
halos. Thus we find strong support for the extension of the steep luminosity
function to M_UV = -13 at z > 6, consistent with the number of faint galaxies
needed to reionize the Universe under standard assumptions.


title:
Detecting Ultralight Bosonic Dark Matter via Absorption in
  Superconductors

abstract:
  Superconducting targets have recently been proposed for the direct detection
of dark matter as light as a keV, via elastic scattering off conduction
electrons in Cooper pairs. Detecting such light dark matter requires
sensitivity to energies as small as the superconducting gap of O(meV). Here we
show that these same superconducting devices can detect much lighter DM, of meV
to eV mass, via dark matter absorption on a conduction electron, followed by
emission of an athermal phonon. We demonstrate the power of this setup for
relic kinetically mixed hidden photons, pseudoscalars, and scalars, showing the
reach can exceed current astrophysical and terrestrial constraints with only a
moderate exposure.


title: The complete HEFT Lagrangian after the LHC Run I

abstract:
  The complete effective chiral Lagrangian for a dynamical Higgs is presented
and constrained by means of a global analysis including electroweak precision
data together with Higgs and triple gauge boson coupling data from the LHC
Run~I. The operators' basis up to next-to-leading order in the expansion
consists of 148 (188 considering right-handed neutrinos) flavour universal
terms and it is presented here making explicit the custodial nature of the
operators. This effective Lagrangian provides the most general description of
the physical Higgs couplings once the electroweak symmetry is assumed, and it
allows for deviations from the $SU(2)_L$ doublet nature of the Standard Model
Higgs. The comparison with the effective linear Lagrangian constructed with an
exact $SU(2)_L$ doublet Higgs and considering operators with at most canonical
dimension six is presented. A promising strategy to disentangle the two
descriptions consists in analysing i) anomalous signals present only in the
chiral Lagrangian and not expected in the linear one, that are potentially
relevant for LHC searches, and ii) decorrelation effects between observables
that are predicted to be correlated in the linear case and not in the chiral
one. The global analysis presented here, that includes several kinematic
distributions, is crucial for reducing the allowed parameter space and for
controlling the correlations between parameters. This improves previous studies
aimed at investigating the Higgs Nature and the origin of the electroweak
symmetry breaking.


title:
The FMOS-COSMOS survey of star-forming galaxies at z~1.6. IV: Excitation
  state and chemical enrichment of the interstellar medium

abstract:
  We investigate the physical conditions of ionized gas in high-z star-forming
galaxies using diagnostic diagrams based on the rest-frame optical emission
lines. The sample consists of 701 galaxies with an Ha detection at $1.4\lesssim
z\lesssim1.7$, from the FMOS-COSMOS survey, that represent the normal
star-forming population over the stellar mass range $10^{9.6} \lesssim
M_\ast/M_\odot \lesssim 10^{11.6}$ with those at $M_\ast>10^{11}~M_\odot$ being
well sampled. We confirm an offset of the average location of star-forming
galaxies in the BPT diagram ([OIII]/Hb vs. [NII]/Ha), primarily towards higher
[OIII]/Hb, compared with local galaxies. Based on the [SII] ratio, we measure
an electron density ($n_e=220^{+170}_{-130}~\mathrm{cm^{-3}}$), that is higher
than that of local galaxies. Based on comparisons to theoretical models, we
argue that changes in emission-line ratios, including the offset in the BPT
diagram, are caused by a higher ionization parameter both at fixed stellar mass
and at fixed metallicity with additional contributions from a higher gas
density and possibly a hardening of the ionizing radiation field. Ionization
due to AGNs is ruled out as assessed with Chandra. As a consequence, we revisit
the mass-metallicity relation using [NII]/Ha and a new calibration including
[NII]/[SII] as recently introduced by Dopita et al. Consistent with our
previous results, the most massive galaxies ($M_\ast\gtrsim10^{11}~M_\odot$)
are fully enriched, while those at lower masses have metallicities lower than
local galaxies. Finally, we demonstrate that the stellar masses, metallicities
and star formation rates of the FMOS sample are well fit with a
physically-motivated model for the chemical evolution of star-forming galaxies.


title: The EAGLE simulations: atomic hydrogen associated with galaxies

abstract:
  We examine the properties of atomic hydrogen (HI) associated with galaxies in
the EAGLE simulations of galaxy formation. EAGLE's feedback parameters were
calibrated to reproduce the stellar mass function and galaxy sizes at $z=0.1$,
and we assess whether this calibration also yields realistic HI properties. We
estimate the self-shielding density with a fitting function calibrated using
radiation transport simulations, and correct for molecular hydrogen with
empirical or theoretical relations. The `standard-resolution' simulations
systematically underestimate HI column densities, leading to an HI deficiency
in low-mass ($M_\star < 10^{10}M_\odot$) galaxies and poor reproduction of the
observed HI mass function. These shortcomings are largely absent from EAGLE
simulations featuring a factor of 8 (2) better mass (spatial) resolution,
within which the HI mass of galaxies evolves more mildly from $z=1$ to $0$ than
in the standard-resolution simulations. The largest-volume simulation
reproduces the observed clustering of HI systems, and its dependence on
HI-richness. At fixed $M_\star$, galaxies acquire more HI in simulations with
stronger feedback, as they become associated with more massive haloes and
higher infall rates. They acquire less HI in simulations with a greater star
formation efficiency, since the star formation and feedback necessary to
balance the infall rate is produced by smaller gas reservoirs. The simulations
indicate that the HI of present-day galaxies was acquired primarily by the
smooth accretion of ionized, intergalactic gas at $z\simeq1$, which later
self-shields, and that only a small fraction is contributed by the
reincorporation of gas previously heated strongly by feedback. HI reservoirs
are highly dynamic: over $40$ percent of HI associated with $z=0.1$ galaxies is
converted to stars or ejected by $z=0$.


title:
Optical Absorption by Dirac Excitons in Single-Layer Transition-Metal
  Dichalcogenides

abstract:
  We develop an analytically solvable model able to qualitatively explain
nonhydrogenic exciton spectra observed recently in two-dimensional (2d)
semiconducting transition metal dichalcogenides. Our exciton Hamiltonian
explicitly includes additional angular momentum associated with the pseudospin
degree of freedom unavoidable in 2d semiconducting materials with honeycomb
structure. We claim that this is the key ingredient for understanding the
nonhydrogenic exciton spectra that was missing so far.


title:
Ly$\alpha$ Spectra from Multiphase Outflows, and their Connection to
  Shell Models

abstract:
  We perform Lyman-$\alpha$ (Ly$\alpha$) Monte-Carlo radiative transfer
calculations on a suite of $2500$ models of multiphase, outflowing media, which
are characterized by $14$ parameters. We focus on the Ly$\alpha$ spectra
emerging from these media, and investigate which properties are dominant in
shaping the emerging Ly$\alpha$ profile. Multiphase models give rise to a wide
variety of emerging spectra, including single, double and triple peaked
spectra. We find that the dominant parameters in shaping the spectra include
(i) the cloud covering factor, $f_c$, in agreement with earlier studies, and
(ii) the temperature and number density of residual HI in the hot ionized
medium. We attempt to reproduce spectra emerging from multiphase models with
`shell models' which are commonly used to fit observed Ly$\alpha$ spectra, and
investigate the connection between shell-model parameters and the physical
parameters of the clumpy media. In shell models, the neutral hydrogen content
of the shell is one of the key parameters controlling Ly$\alpha$ radiative
transfer. Because Ly$\alpha$ spectra emerging from multi-phase media depend
much less on the neutral hydrogen content of the clumps, the shell model
parameters such as HI column density (but also shell velocity and dust content)
are generally not well matched to the associated physical parameters of clumpy
media.


title:
Probing the boundary between star clusters and dwarf galaxies: A MUSE
  view on the dynamics of Crater/Laevens I

abstract:
  We present MUSE observations of the debated ultra faint stellar system
Crater. We spectroscopically confirm 26 member stars of this system via radial
velocity measurements. We derive the systematic instrumental velocity
uncertainty of MUSE spectra to be 2.27$\rm \,km\,s^{-1}$. This new dataset
increases the confirmed member stars of Crater by a factor of 3. One out of
three bright blue stars and a fainter blue star just above the
main-sequence-turn-off are also found to be likely members of the system. The
observations reveal that Crater has a systemic radial velocity of $v_{\rm
sys}=148.18^{\rm +1.08}_{\rm -1.15}\rm \,km\,s^{-1}$, whereas the most likely
velocity dispersion of this system is $\sigma_{\rm v}=2.04^{\rm +2.19}_{\rm
-1.06} \rm \,km\,s^{-1}$. The total dynamical mass of the system, assuming
dynamical equilibrium is then $M_{\rm tot}=1.50^{+4.9}_{-1.2}\cdot 10^{\rm
5}M_{\odot}$ implying a mass-to-light ratio of M/L$_{\rm
V}$=8.52$^{+28.0}_{-6.5}\, M_{\odot}/L_{\odot}$, which is consistent with a
purely baryonic stellar population within its errors and no significant
evidence for the presence dark matter was found. We also find evidence for a
velocity gradient in the radial velocity distribution. We conclude that our
findings strongly support that Crater is a faint intermediate-age outer halo
globular cluster and not a dwarf galaxy.


title: Composite fermi liquids in the lowest Landau level

abstract:
  We study composite fermi liquid (CFL) states in the lowest Landau level (LLL)
limit at a generic filling $\nu = \frac{1}{n}$. We begin with the old
observation that, in compressible states, the composite fermion in the lowest
Landau level should be viewed as a charge-neutral particle carrying vorticity.
This leads to the absence of a Chern-Simons term in the effective theory of the
CFL. We argue here that instead a Berry curvature should be enclosed by the
fermi surface of composite fermions, with the total Berry phase fixed by the
filling fraction $\phi_B=-2\pi\nu$. We illustrate this point with the CFL of
fermions at filling fractions $\nu=1/2q$ and (single and two-component) bosons
at $\nu=1/(2q+1)$. The Berry phase leads to sharp consequences in the transport
properties including thermal and spin Hall conductances, which in the RPA
approximation are distinct from the standard Halperin-Lee-Read predictions. We
emphasize that these results only rely on the LLL limit, and do not require
particle-hole symmetry, which is present microscopically only for fermions at
$\nu=1/2$. Nevertheless, we show that the existing LLL theory of the composite
fermi liquid for bosons at $\nu=1$ does have an emergent particle-hole
symmetry. We interpret this particle-hole symmetry as a transformation between
the empty state at $\nu=0$ and the boson integer quantum hall state at $\nu=2$.
This understanding enables us to define particle-hole conjugates of various
bosonic quantum Hall states which we illustrate with the bosonic Jain and
Pfaffian states. The bosonic particle-hole symmetry can be realized exactly on
the surface of a three-dimensional boson topological insulator. We also show
that with the particle-hole and spin $SU(2)$ rotation symmetries, there is no
gapped topological phase for bosons at $\nu=1$.


title: Renormalized entanglement entropy

abstract:
  We develop a renormalization method for holographic entanglement entropy
based on area renormalization of entangling surfaces. The renormalized
entanglement entropy is derived for entangling surfaces in asymptotically
locally anti-de Sitter spacetimes in general dimensions and for entangling
surfaces in four dimensional holographic renormalization group flows. The
renormalized entanglement entropy for disk regions in $AdS_4$ spacetimes agrees
precisely with the holographically renormalized action for $AdS_4$ with
spherical slicing and hence with the F quantity, in accordance with the
Casini-Huerta-Myers map. We present a generic class of holographic RG flows
associated with deformations by operators of dimension $3/2 < \Delta < 5/2$ for
which the F quantity increases along the RG flow, hence violating the strong
version of the F theorem. We conclude by explaining how the renormalized
entanglement entropy can be derived directly from the renormalized partition
function using the replica trick i.e. our renormalization method for the
entanglement entropy is inherited directly from that of the partition function.
We show explicitly how the entanglement entropy counterterms can be derived
from the standard holographic renormalization counterterms for asymptotically
locally anti-de Sitter spacetimes.


title: The holographic F theorem

abstract:
  The F theorem states that, for a unitary three dimensional quantum field
theory, the F quantity defined in terms of the partition function on a three
sphere is positive, stationary at fixed point and decreases monotonically along
a renormalization group flow. We construct holographic renormalization group
flows corresponding to relevant deformations of three-dimensional conformal
field theories on spheres, working to quadratic order in the source. For these
renormalization group flows, the F quantity at the IR fixed point is always
less than F at the UV fixed point, but F increases along the RG flow for
deformations by operators of dimension $3/2 < \Delta < 5/2$. Therefore the
strongest version of the F theorem is in general violated.


title: Counting paths with Schur transitions

abstract:
  In this work we explore the structure of the branching graph of the unitary
group using Schur transitions. We find that these transitions suggest a new
combinatorial expression for counting paths in the branching graph. This
formula, which is valid for any rank of the unitary group, reproduces known
asymptotic results. We proceed to establish the general validity of this
expression by a formal proof. The form of this equation strongly hints towards
a quantum generalization. Thus, we introduce a notion of quantum relative
dimension and subject it to the appropriate consistency tests. This new
quantity finds its natural environment in the context of RCFTs and fractional
statistics; where the already established notion of quantum dimension has
proven to be of great physical importance.


title: The Impact of the Dusty Torus on Obscured Quasar Halo Mass Measurements

abstract:
  Recent studies have found that obscured quasars cluster more strongly and are
thus hosted by dark matter haloes of larger mass than their unobscured
counterparts. These results pose a challenge for the simplest unification
models, in which obscured objects are intrinsically the same as unobscured
sources but seen through a dusty line of sight. There is general consensus that
a structure like a "dusty torus" exists, meaning that this intrinsic similarity
is likely the case for at least some subset of obscured quasars. However, the
larger host halo masses of obscured quasars implies that there is a second
obscured population that has an even higher clustering amplitude and typical
halo mass. Here, we use simple assumptions about the host halo mass
distributions of quasars, along with analytical methods and cosmological
$N$-body simulations to isolate the signal from this population. We provide
values for the bias and halo mass as a function of the fraction of the
"non-torus obscured" population. Adopting a reasonable value for this fraction
of $\sim$25% implies a non-torus obscured quasar bias that is much higher than
the observed obscured quasar bias, because a large fraction of the obscured
population shares the same clustering strength as the unobscured objects. For
this non-torus obscured population, we derive a bias of $\sim$3, and typical
halo masses of $\sim3\times10^{13}$ M$_{\odot}/h$ at $z=1$. These massive
haloes are likely the descendants of high-mass unobscured quasars at high
redshift, and will evolve into members of galaxy groups at $z=0$.


title: Lifting Enhanced Factorization Systems to Functor $ 2 $-Categories

abstract:
  In this paper we give sufficient conditions for lifting an enhanced
factorization system $ (\mathcal{E}, \mathcal{M}) $ on a $ 2 $-category $
\mathbf{D} $ to the functor $ 2 $-category $ \mathbf{D}^{\mathbf{C}} $, where $
\mathbf{C} $ is a small $ 2 $-category. Due to previous work of Lack, our work
provides coherence results for $ 2 $-monads on functor $ 2 $-categories. These
coherence results are of immediate interest to an ongoing collaboration of
Guillou, May, Merling, and Osorno on equivariant infinite loop space theory.


title:
Hypocoercive estimates on foliations and velocity spherical Brownian
  motion

abstract:
  By further developing the generalized $\Gamma$-calculus for hypoelliptic
operators, we prove hypocoercive estimates for a large class of Kolmogorov type
operators which are defined on non necessarily totally geodesic Riemannian
foliations. We study then in detail the example of the velocity spherical
Brownian motion, whose generator is a step-3 generating hypoelliptic
H\"ormander's type operator. To prove hypocoercivity in that case, the key
point is to show the existence of a convenient Riemannian foliation associated
to the diffusion. We will then deduce, under suitable geometric conditions, the
convergence to equilibrium of the diffusion in $H^1$ and in $L^2$.


title: The Demographics of galactic bulges in the SDSS database

abstract:
  We present a new database of our two-dimensional bulge-disk decompositions
for 14,233 galaxies drawn from SDSS DR12 in order to examine the properties of
bulges residing in the local universe ($0.005 < z < 0.05$). We performed
decompositions in $g$ and $r$ bands by utilizing the {\sc{galfit}} software.
The bulge colors and bulge-to-total ratios are found to be sensitive to the
details in the decomposition technique, and hence we hereby provide full
details of our method. The $g-r$ colors of bulges derived are almost constantly
red regardless of bulge size except for the bulges in the low bulge-to-total
ratio galaxies ($B/T_{\rm r} \lesssim 0.3$). Bulges exhibit similar scaling
relations to those followed by elliptical galaxies, but the bulges in galaxies
with lower bulge-to-total ratios clearly show a gradually larger departure in
slope from the elliptical galaxy sequence. The scatters around the scaling
relations are also larger for the bulges in galaxies with lower bulge-to-total
ratios. Both the departure in slopes and larger scatters are likely originated
from the presence of young stars. The bulges in galaxies with low
bulge-to-total ratios show signs of a frosting of young stars so substantial
that their luminosity-weighted Balmer-line ages are as small as 1\,Gyr in some
cases. While bulges seem largely similar in optical properties to elliptical
galaxies, they do show clear and systematic departures as a function of
bulge-to-total ratio. The stellar properties and perhaps associated formation
processes of bulges seem much more diverse than those of elliptical galaxies.


title:
Non-convex Global Minimization and False Discovery Rate Control for the
  TREX

abstract:
  The TREX is a recently introduced method for performing sparse
high-dimensional regression. Despite its statistical promise as an alternative
to the lasso, square-root lasso, and scaled lasso, the TREX is computationally
challenging in that it requires solving a non-convex optimization problem. This
paper shows a remarkable result: despite the non-convexity of the TREX problem,
there exists a polynomial-time algorithm that is guaranteed to find the global
minimum. This result adds the TREX to a very short list of non-convex
optimization problems that can be globally optimized (principal components
analysis being a famous example). After deriving and developing this new
approach, we demonstrate that (i) the ability of the preexisting TREX heuristic
to reach the global minimum is strongly dependent on the difficulty of the
underlying statistical problem, (ii) the new polynomial-time algorithm for TREX
permits a novel variable ranking and selection scheme, (iii) this scheme can be
incorporated into a rule that controls the false discovery rate (FDR) of
included features in the model. To achieve this last aim, we provide an
extension of the results of Barber & Candes (2015) to establish that the
knockoff filter framework can be applied to the TREX. This investigation thus
provides both a rare case study of a heuristic for non-convex optimization and
a novel way of exploiting non-convexity for statistical inference.


title: Metallic Coaxial Nanolasers

abstract:
  The last two decades have witnessed tremendous advancements in the area of
nanophotonics and plasmonics. Undoubtedly, the introduction of metallic
structures has opened a path towards light confinement and manipulation at the
subwavelength scale { a regime that was previously thought to be out of reach
in optics. Of central importance is to devise efficient light sources to power
up the future nanoscale optical circuits. Coaxial resonators can provide a
platform to implement such subwavelength sources. They support ultrasmall
cavity modes and offer large mode-emitter overlap as well as multifold
scalability. Given their large modulation bandwidth, they hold promise for high
speed optical interconnects { where they can be used for light generation and
modulation simultaneously. In addition, the possibility of thresholdless
operation in such devices may have implications in developing the next
generation of efficient lighting systems. In this review article, the physics
and applications of coaxial nanolasers will be discussed.


title:
Observation of b$_2$ symmetry vibrational levels of the SO$_2$
  $\tilde{\mbox{C}}$ $^1$B$_2$ state: Vibrational level staggering, Coriolis
  interactions, and rotation-vibration constants

abstract:
  The $\mathrm{\tilde{C}}$ $^1$B$_2$ state of SO$_2$ has a double-minimum
potential in the antisymmetric stretch coordinate, such that the minimum energy
geometry has nonequivalent SO bond lengths. However, low-lying levels with odd
quanta of antisymmetric stretch (b$_2$ vibrational symmetry) have not
previously been observed because transitions into these levels from the
zero-point level of the $\mathrm{\tilde{X}}$ state are vibronically forbidden.
We use IR-UV double resonance to observe the b$_2$ vibrational levels of the
$\mathrm{\tilde{C}}$ state below 1600 cm$^{-1}$ of vibrational excitation. This
enables a direct characterization of the vibrational level staggering that
results from the double-minimum potential. In addition, it allows us to
deperturb the strong $c$-axis Coriolis interactions between levels of a$_1$ and
b$_2$ vibrational symmetry, and to determine accurately the vibrational
dependence of the rotational constants in the distorted $\mathrm{\tilde{C}}$
electronic state.


title: Validation of computer simulations of the HyQ robot

abstract:
  This short technical report illustrates the results of a test procedure we
performed to validate the computer simulation of the HyQ robot.


title: An algebra of Stein operators

abstract:
  We build upon recent advances on the distributional aspect of Stein's method
to propose a novel and flexible technique for computing Stein operators for
random variables that can be written as products of independent random
variables. We show that our results are valid for a wide class of distributions
including normal, beta, variance-gamma, generalized gamma and many more. Our
operators are $k$th degree differential operators with polynomial coefficients;
they are straightforward to obtain even when the target density bears no
explicit handle. As an application, we derive a new formula for the density of
the product of $k$ independent symmetric variance-gamma distributed random
variables.


title:
On the structure of monomial complete intersections in positive
  characteristic

abstract:
  In this paper we study the Lefschetz properties of monomial complete
intersections in positive characteristic. We give a complete classification of
the strong Lefschetz property when the number of variables is at least three,
which proves a conjecture by Cook II. We also extend earlier results on the
weak Lefschetz property by dropping the assumption on the residue field being
infinite, and by giving new sufficient criteria.


title: Disappearance of the Progenitor of Supernova iPTF13bvn

abstract:
  Supernova (SN) iPTF13bvn in NGC 5806 was the first Type Ib SN to have been
tentatively associated with a progenitor candidate in pre-explosion images. We
performed deep ultraviolet (UV) and optical Hubble Space Telescope (HST)
observations of the SN site 740 days after explosion. We detect an object in
the optical bands that is fainter than the pre-explosion object. This dimming
is likely not produced by dust absorption in the ejecta; thus, our finding
confirms the connection of the progenitor candidate with the SN. The object in
our data is likely dominated by the fading SN, which implies that the pre-SN
flux is mostly due to the progenitor. We compare our revised pre-SN photometry
with previously proposed progenitor models. Although binary progenitors are
favored, models need to be refined. In particular, to comply with our deep UV
detection limit, any companion star must be less luminous than a late-O star or
substantially obscured by newly formed dust. A definitive progenitor
characterization will require further observations to disentangle the
contribution of a much fainter SN and its environment.


title: Stochastic Laplacian growth

abstract:
  A point source on a plane constantly emits particles which rapidly diffuse
and then stick to a growing cluster. The growth probability of a cluster is
presented as a sum over all possible scenarios leading to the same final shape.
The classical point for the action, defined as a minus logarithm of the growth
probability, describes the most probable scenario and reproduces the Laplacian
growth equation, which embraces numerous fundamental free boundary dynamics in
non-equilibrium physics. For non-classical scenarios we introduce virtual point
sources, in which presence the action becomes the Kullback-Leibler entropy.
Strikingly, this entropy is shown to be the sum of electrostatic energies of
layers grown per elementary time unit. Hence the growth probability of the
presented non-equilibrium process obeys the Gibbs-Boltzmann statistics, which,
as a rule, is not applied out from equilibrium. Each layer's probability is
expressed as a product of simple factors in an auxiliary complex plane after a
properly chosen conformal map. The action at this plane is a sum of Robin
functions, which solve the Liouville equation. At the end we establish
connections of our theory with the tau-function of the integrable Toda
hierarchy and with the Liouville theory for non-critical quantum strings.

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


title:
Completely positive and completely positive semidefinite tensor
  relaxations for polynomial optimization

abstract:
  Completely positive (CP) tensors, which correspond to a generalization of CP
matrices, allow to reformulate or approximate a general polynomial optimization
problem (POP) with a conic optimization problem over the cone of CP tensors.
Similarly, completely positive semidefinite (CPSD) tensors, which correspond to
a generalization of positive semidefinite (PSD) matrices, can be used to
approximate general POPs with a conic optimization problem over the cone of
CPSD tensors. In this paper, we study CP and CPSD tensor relaxations for
general POPs and compare them with the bounds obtained via a Lagrangian
relaxation of the POPs. This shows that existing results in this direction for
quadratic POPs extend to general POPs. Also, we provide some tractable
approximation strategies for CP and CPSD tensor relaxations. These
approximation strategies show that, with a similar computational effort, bounds
obtained from them for general POPs can be tighter than bounds for these
problems obtained by reformulating the POP as a quadratic POP, which
subsequently can be approximated using CP and PSD matrices. To illustrate our
results, we numerically compare the bounds obtained from these relaxation
approaches on small scale fourth-order degree POPs.


title: Cosmological solutions in modified gravity with monomial nonlocality

abstract:
  We consider cosmological properties of modified gravity with nonlocal term $
R^p\mathcal{F}(\Box)R^q$ in its Lagrangian. Equations of motion are presented.
For the flat FLRW metric, and some particular values of natural numbers $p$ and
$q$ cosmological solutions of the form $a(t)= C e^{- \frac \gamma{12}t^2}$ are
found.


title:
Phase separation in iron chalcogenide superconductor Rb0.8+xFe1.6+ySe2
  as seen by Raman light scattering and band structure calculations

abstract:
  We report Raman light scattering in the phase separated superconducting
single crystal Rb0.77Fe1.61Se2 with Tc = 32 K. The spectra have been measured
in a wide temperature range 3K -500K. The observed phonon lines from the
majority vacancy ordered Rb2Fe4Se5 (245) antiferromagnetic phase with TN= 525 K
demonstrate modest anomalies in frequency, intensity and halfwidth at the
superconductive phase transition. We identify phonon lines from the minority
compressed Rb{\delta}Fe2Se2 (122) conductive phase. The superconducting gap
with dx2-y2 symmetry is also detected in our spectra. In the range 0-600 cm-1
we observed the low intensive but highly polarized B1g-type background which
becomes well structured under cooling. The possible magnetic or multiorbital
origin of this background has been discussed. We argue that phase separation in
M0.8+xFe1.6+ySe2 has pure magnetic origin. It occurs below Neel temperature
when iron magnetic moment achieves some critical magnitude. We state that there
is a spacer between the majority 245 and minority 122 phases. Using ab-initio
spin polarized band structure calculations we demonstrate that compressed
vacancy ordered Rb2Fe4Se5 phase can be conductive and therefore may serve as a
protective interface spacer between the pure metallic Rb{\delta}Fe2Se2 phase
and the insulating Rb2Fe4Se5 phase providing the percolative Josephson-junction
like superconductivity in the whole sample of Rb0.8+xFe1.6+ySe2 Our lattice
dynamics calculations show significant difference in the phonon spectra of the
conductive and insulating Rb2Fe4.Se5 phases.


title: Simulating LTE and Wi-Fi Coexistence in Unlicensed Spectrum with ns-3

abstract:
  The use of unlicensed spectrum for future LTE systems raises concerns about
its impact on co-located Wi-Fi networks. We report herein on extensions to a
popular network simulator, known as ns-3, to model such coexistence. To our
knowledge, this simulator is novel in two important ways. First, it is
presently the only freely available simulator for coexistence studies, and as
open source software, it offers new opportunities for reproducible research and
collaborative model development. Second, we are not aware of other simulators
with similar wireless models that allow full system studies to be conducted,
such as performance evaluation of upper-layer protocols in a coexistence
environment. We illustrate the value of a system simulator by describing a
simulation campaign for the indoor scenario designed by 3GPP RAN1 using new
ns-3 models for Release 13 LTE Listen Before Talk (LBT) techniques, intended
for fair coexistence with Wi-Fi. LBT models have been widely simulated at the
link and physical layer by many companies in 3GPP RAN1. We first show that we
are able to tune the scenario to reproduce similar performance metrics to those
reported in the literature. We then extend the simulations by adding TCP to the
file transfers and explore the different behaviour observed. Our initial study
reveals that there remain many open questions about how LBT should be
implemented to achieve good coexistence properties, and that a broader scope of
implementation issues, traffic models, and fuller system models should be
studied further before drawing final conclusions on the LBT coexistence
performance.


title: Quasi-chemical approximation for polyatomic mixtures

abstract:
  The statistical thermodynamics of binary mixtures of polyatomic species was
developed on a generalization in the spirit of the lattice-gas model and the
quasi-chemical approximation (QCA). The new theoretical framework is obtained
by combining: (i) the exact analytical expression for the partition function of
non-interacting mixtures of linear $k$-mers and $l$-mers (species occupying $k$
sites and $l$ sites, respectively) adsorbed in one dimension, and its extension
to higher dimensions; and (ii) a generalization of the classical QCA for
multicomponent adsorbates and multisite-occupancy adsorption. The process is
analyzed through the partial adsorption isotherms corresponding to both species
of the mixture. Comparisons with analytical data from Bragg-Williams
approximation (BWA) and Monte Carlo simulations are performed in order to test
the validity of the theoretical model. Even though a good fitting is obtained
from BWA, it is found that QCA provides a more accurate description of the
phenomenon of adsorption of interacting polyatomic mixtures.


title: An introduction to large deviations for random graphs

abstract:
  This article gives an overview of the emerging literature on large deviations
for random graphs. Written for the general mathematical audience, the article
begins with a short introduction to the theory of large deviations. This is
followed by a description of some large deviation questions about random
graphs, and an outline of the recent progress on this topic. A more elaborate
discussion follows, with a brief account of graph limit theory and its
application in constructing a large deviation theory for dense random graphs.
The role of Szemer\'edi's regularity lemma is explained, together with a sketch
of the proof of the main large deviation result and some examples. Applications
to exponential random graph models are briefly touched upon. The remainder of
the paper is devoted to large deviations for sparse graphs. Since the
regularity lemma is not applicable in the sparse regime, new tools are needed.
Fortunately, there have been several new breakthroughs that managed to achieve
the goal by an indirect method. These are discussed, together with an
exposition of the underlying theory. The last section contains a list of open
problems.


title: Particle-hole cumulant approach for inelastic losses in x-ray spectra

abstract:
  Inelastic losses in core level x-ray spectra arise from many-body
excitations, leading to broadening and damping as well as satellite peaks in
x-ray photoemission (XPS) and x-ray absorption (XAS) spectra. Here we present a
practical approach for calculating these losses based on a cumulant
representation of the particle-hole Green's function, a quasi-boson
approximation, and a partition of the cumulant into extrinsic, intrinsic and
interference terms. The intrinsic losses are calculated using real-time,
time-dependent density functional theory while the extrinsic losses are
obtained from the GW approximation of the photo-electron self-energy and the
interference terms are approximated. These effects are included in the spectra
using a convolution with an energy dependent particle-hole spectral function.
The approach elucidates the nature of the spectral functions in XPS and XAS and
explains the significant cancellation between extrinsic and intrinsic losses.
Edge-singularity effects in metals are also accounted for. Illustrative results
are presented for the XPS and XAS for both weakly and more correlated systems.


title:
Computing localized representations of the kohn-sham subspace via
  randomization and refinement

abstract:
  Localized representation of the Kohn-Sham subspace plays an important role in
quantum chemistry and materials science. The recently developed selected
columns of the density matrix (SCDM) method [J. Chem. Theory Comput. 11, 1463,
2015] is a simple and robust procedure for finding a localized representation
of a set of Kohn-Sham orbitals from an insulating system. The SCDM method
allows the direct construction of a well conditioned (or even orthonormal) and
localized basis for the Kohn-Sham subspace. The SCDM algorithm avoids the use
of an optimization procedure and does not depend on any adjustable parameters.
The most computationally expensive step of the SCDM method is a column pivoted
QR factorization that identifies the important columns for constructing the
localized basis set. In this paper, we develop a two stage approximate column
selection strategy to find the important columns at much lower computational
cost. We demonstrate the effectiveness of this process using the dissociation
process of a BH$_3$NH$_3$ molecule, an alkane chain and a supercell with 256
water molecules. Numerical results for the large collection of water molecules
show that two stage localization procedure can be more than 30 times faster
than the original SCDM algorithm and compares favorably with the popular
Wannier90 package.


title:
Electric and Magnetic response in dielectric dark states for low loss
  subwavelength optical meta atoms

abstract:
  Created surfaces or meta surfaces, composed of appropriately shaped
sub-wavelength structures, namely, meta-atoms, control light at wavelength
scales. Historically, meta surfaces have used radiating metallic resonators as
wavelength inclusions. However, while resonant optical meta surfaces made from
metal have been sub-wavelength in the propagation direction, they are too loss
for many applications.


title: Refining Architectures of Deep Convolutional Neural Networks

abstract:
  Deep Convolutional Neural Networks (CNNs) have recently evinced immense
success for various image recognition tasks. However, a question of paramount
importance is somewhat unanswered in deep learning research - is the selected
CNN optimal for the dataset in terms of accuracy and model size? In this paper,
we intend to answer this question and introduce a novel strategy that alters
the architecture of a given CNN for a specified dataset, to potentially enhance
the original accuracy while possibly reducing the model size. We use two
operations for architecture refinement, viz. stretching and symmetrical
splitting. Our procedure starts with a pre-trained CNN for a given dataset, and
optimally decides the stretch and split factors across the network to refine
the architecture. We empirically demonstrate the necessity of the two
operations. We evaluate our approach on two natural scenes attributes datasets,
SUN Attributes and CAMIT-NSAD, with architectures of GoogleNet and VGG-11, that
are quite contrasting in their construction. We justify our choice of datasets,
and show that they are interestingly distinct from each other, and together
pose a challenge to our architectural refinement algorithm. Our results
substantiate the usefulness of the proposed method.


title: Counting odd cycles in locally dense graphs

abstract:
  We prove that for any given $\varepsilon>0$ and $d\in [0,1]$, every
sufficiently large $(\varepsilon, d)$-dense graph $G$ contains for each odd
integer $r$ at least $(d^r-\varepsilon)|V(G)|^r$ cycles of length $r$. Here,
$G$ being $(\varepsilon, d)$-dense means that every set $X$ containing at
least~$\varepsilon\,|V(G)|$ vertices spans at least $\tfrac d2\, |X|^2$ edges,
and what we really count is the number of homomorphisms from an $r$-cycle into
$G$.
  The result adresses a question of Y. Kohayakawa, B. Nagle, V. R\"odl, and M.
Schacht.


title: Quantum private comparison protocol without a third party

abstract:
  To evade the well-known impossibility of unconditionally secure quantum
two-party computations, previous quantum private comparison protocols have to
adopt a third party. Here we study how far we can go with two parties only. We
propose a very feasible and efficient protocol. Intriguingly, although the
average amount of information leaked cannot be made arbitrarily small, we find
that it never exceeds 14 bits for any length of the bit-string being compared.


title:
A unified framework for harmonic analysis of functions on directed
  graphs and changing data

abstract:
  We present a general framework for studying harmonic analysis of functions in
the settings of various emerging problems in the theory of diffusion geometry.
The starting point of the now classical diffusion geometry approach is the
construction of a kernel whose discretization leads to an undirected graph
structure on an unstructured data set. We study the question of constructing
such kernels for directed graph structures, and argue that our construction is
essentially the only way to do so using discretizations of kernels. We then use
our previous theory to develop harmonic analysis based on the singular value
decomposition of the resulting non-self-adjoint operators associated with the
directed graph. Next, we consider the question of how functions defined on one
space evolves to another space in the paradigm of changing data sets recently
introduced by Coifman and Hirn. While the approach of Coifman and Hirn require
that the points on one space should be in a known one-to-one correspondence
with the points on the other, our approach allows the identification of only a
subset of landmark points. We introduce a new definition of distance between
points on two spaces, construct localized kernels based on the two spaces and
certain interaction parameters, and study the evolution of smoothness of a
function on one space to its lifting to the other space via the landmarks. We
develop novel mathematical tools that enable us to study these seemingly
different problems in a unified manner.


title:
Colloidal particle adsorption at liquid interfaces: Capillary driven
  dynamics and thermally activated kinetics

abstract:
  The adsorption of single colloidal microparticles (0.5--1 $\mu$m radius) at a
water-oil interface has been recently studied experimentally using digital
holographic microscopy [Kaz \textit{et al., Nat. Mater.}, 2012, \textbf{11},
138--142]. An initially fast adsorption dynamics driven by capillary forces is
followed by an unexpectedly slow relaxation to equilibrium that is logarithmic
in time and can span hours or days. The slow relaxation kinetics has been
attributed to the presence of surface "defects" with nanoscale dimensions
(1--5\,nm) that induce multiple metastable configurations of the contact line
perimeter. A kinetic model considering thermally activated transitions between
such metastable configurations has been proposed [Colosqui \textit{et al.,
Phys. Rev. Lett.}, 2013, \textbf{111}, 028302] to predict both the relaxation
rate and the crossover point to the slow logarithmic regime. However, the
adsorption dynamics observed experimentally before the crossover point has
remained unstudied. In this work, we propose a Langevin model that is able to
describe the entire adsorption process of single colloidal particles by
considering metastable states produced by surface defects and thermal motion of
the particle and liquid interface. Invoking the fluctuation dissipation
theorem, we introduce a drag term that considers significant dissipative forces
induced by thermal fluctuations of the liquid interface. Langevin dynamics
simulations based on the proposed adsorption model yield close agreement with
experimental observations for different microparticles, capturing the crossover
from (fast) capillary driven dynamics to (slow) thermally activated kinetics.


title: Certifiably Optimal Low Rank Factor Analysis

abstract:
  Factor Analysis (FA) is a technique of fundamental importance that is widely
used in classical and modern multivariate statistics, psychometrics and
econometrics. In this paper, we revisit the classical rank-constrained FA
problem, which seeks to approximate an observed covariance matrix
($\boldsymbol\Sigma$), by the sum of a Positive Semidefinite (PSD) low-rank
component ($\boldsymbol\Theta$) and a diagonal matrix ($\boldsymbol\Phi$) (with
nonnegative entries) subject to $\boldsymbol\Sigma - \boldsymbol\Phi$ being
PSD. We propose a flexible family of rank-constrained, nonlinear Semidefinite
Optimization based formulations for this task. We introduce a reformulation of
the problem as a smooth optimization problem with convex compact constraints
and propose a unified algorithmic framework, utilizing state of the art
techniques in nonlinear optimization to obtain high-quality feasible solutions
for our proposed formulation. At the same time, by using a variety of
techniques from discrete and global optimization, we show that these solutions
are certifiably optimal in many cases, even for problems with thousands of
variables. Our techniques are general and make no assumption on the underlying
problem data. The estimator proposed herein, aids statistical interpretability,
provides computational scalability and significantly improved accuracy when
compared to current, publicly available popular methods for rank-constrained
FA. We demonstrate the effectiveness of our proposal on an array of synthetic
and real-life datasets. To our knowledge, this is the first paper that
demonstrates how a previously intractable rank-constrained optimization problem
can be solved to provable optimality by coupling developments in convex
analysis and in discrete optimization.


title:
Word2VisualVec: Image and Video to Sentence Matching by Visual Feature
  Prediction

abstract:
  This paper strives to find the sentence best describing the content of an
image or video. Different from existing works, which rely on a joint subspace
for image / video to sentence matching, we propose to do so in a visual space
only. We contribute Word2VisualVec, a deep neural network architecture that
learns to predict a deep visual encoding of textual input based on sentence
vectorization and a multi-layer perceptron. We thoroughly analyze its
architectural design, by varying the sentence vectorization strategy, network
depth and the deep feature to predict for image to sentence matching. We also
generalize Word2VisualVec for matching a video to a sentence, by extending the
predictive abilities to 3-D ConvNet features as well as a visual-audio
representation. Experiments on four challenging image and video benchmarks
detail Word2VisualVec's properties, capabilities for image and video to
sentence matching, and on all datasets its state-of-the-art results.


title: Stability problems for Cantor stochastic differential equations

abstract:
  We consider driftless stochastic differential equations and the diffusions
starting from the positive half line. It is shown that the Feller test for
explosions gives a necessary and sufficient condition to hold pathwise
uniqueness for diffusion coefficients that are positive and monotonically
increasing or decreasing on the positive half line and the value at the origin
is zero. Then, stability problems are studied from the aspect of
H\"older-continuity and a generalized Nakao-Le Gall condition. Comparing the
convergence rate of H\"older-continuous case, the sharpness and stability of
the Nakao-Le Gall condition on Cantor stochastic differential equations is
confirmed.Furthermore, using the Malliavin calculus, we construct a smooth
solution to degenerate second order Fokker-Planck equations under weak
conditions on the coefficients.


title: A fundamental plane for long gamma-ray bursts with X-ray plateaus

abstract:
  A class of long Gamma-Ray Bursts (GRBs) presenting light curves with an
extended plateau phase in their X-ray afterglows obeys a correlation between
the rest frame end time of the plateau, $T_a$, and its corresponding X-ray
luminosity, $L_{a}$, Dainotti et al. (2008). In this work we perform an
analysis of a total sample of 176 {\it Swift} GRBs with known redshifts,
exhibiting afterglow plateaus. By adding a third parameter, that is the peak
luminosity in the prompt emission, $L_{peak}$, we discover the existence of a
new three parameter correlation. The scatter of data about this plane becomes
smaller when a class-specific GRB sample is defined. This sample of 122 GRBs is
selected from the total sample by excluding GRBs with associated Supernovae
(SNe), X-ray flashes and short GRBs with extended emission. {\bf With this
sample the three parameter correlation identifies a GRB `fundamental plane'}.
Moreover, we further limit our analysis to GRBs with lightcurves having good
data coverage and almost flat plateaus, 40 GRBs forming our `gold sample'. The
intrinsic scatter, $\sigma_{int}=0.27 \pm 0.04$, for the three-parameter
correlation for this last subclass is more than twice smaller than the value
for the $L_{a}-T_a$ one, making this the tightest three parameter correlation
involving the afterglow plateau phase. Finally, we also show that a slightly
less tight correlation is present between $L_{peak}$ and a proxy for the total
energy emitted during the plateau phase, $L_a T_a$, confirming the existence of
an energy scaling between prompt and afterglow phases.


title:
Theoretical Analysis on Pseudo-Degenerate Zero-Energy Modes in
  Vacancy-Centered Hexagonal Armchair Nanographene

abstract:
  Deriving mathematical expressions of two zero modes for a $\pi$-band
tight-binding model, we identify a class of bipartite graphs having the same
number of subgraph sites, where each graph represents one of the
quasi-hexagonal nanographene molecule with a center vacancy (VANG). Indeed, in
a VANG molecule, C$_{60}$H$_{24}$, showing stability in a density-functional
simulation at the highest occupied level, there appear two pseudo-degenerate
zero modes, a vacancy-centered quasi-localized zero mode, and extending zero
mode with a $\sqrt{3} \times \sqrt{3}$ structure. Since there is a finite
energy gap between these two zero-energy modes and the other modes, low-lying
states composed of quasi-degenerate zero modes appear as magnetic multiplets.
Thus, the unique magnetic characteristics derived in our theory are expected to
hold for synthesized VANG molecules in reality.


title: How to Diagonalize a MIMO Channel with Arbitrary Transmit Covariance?

abstract:
  Multiple-input multiple-output (MIMO) or multi-antenna communication is a key
technique to achieve high spectral efficiency in wireless systems. For the
point-to-point MIMO channel, it is a well-known result that the channel
singular value decomposition (SVD) based linear precoding and decoding achieves
the channel capacity, which also diagonalizes the MIMO channel into parallel
single-input single-output (SISO) sub-channels for independent encoding and
decoding. However, in multi-user MIMO systems, the optimal transmit covariance
of each MIMO link is generally not its channel SVD based as a result of the
control and balance of the co-channel interference among users. Thus, it
remains unknown whether the linear precoding/decoding strategy is still able to
achieve the capacity of each MIMO link and yet diagonalize its MIMO channel,
with a given set of optimal transmit covariance of all users. This letter
solves this open problem by providing a closed-form capacity-achieving linear
precoder/decoder design that diagonalizes a MIMO channel with arbitrary
transmit covariance. Numerical examples are also provided to validate the
proposed solution in various multi-user MIMO systems.


title: Cohomology of cluster varieties. I. Locally acyclic case

abstract:
  We initiate a systematic study of the cohomology of cluster varieties. We
introduce the Louise property for cluster algebras that holds for all acyclic
cluster algebras, and for most cluster algebras arising from marked surfaces.
For cluster varieties satisfying the Louise property and of full rank, we show
that the cohomology satisfies the curious Lefschetz property of Hausel and
Rodriguez-Villegas, and that the mixed Hodge structure is split over the
rationals. We give a complete description of the highest weight part of the
mixed Hodge structure of these cluster varieties, and develop the notion of a
standard differential form on a cluster variety. We show that the point counts
of these cluster varieties over finite fields can be expressed in terms of
Dirichlet characters. Under an additional integrality hypothesis, the point
counts are shown to be polynomials in the order of the finite field.


title:
Geometrically disordered network models, quenched quantum gravity, and
  critical behavior at quantum Hall plateau transitions

abstract:
  Recent high-precision results for the critical exponent of the localization
length at the integer quantum Hall (IQH) transition differ considerably between
experimental ($\nu_\text{exp} \approx 2.38$) and numerical ($\nu_\text{CC}
\approx 2.6$) values obtained in simulations of the Chalker-Coddington (CC)
network model. We revisit the arguments leading to the CC model and consider a
more general network with geometric (structural) disorder. Numerical
simulations of this new model lead to the value $\nu \approx 2.37$ in very
close agreement with experiments. We argue that in a continuum limit the
geometrically disordered model maps to the free Dirac fermion coupled to
various random potentials (similar to the CC model) but also to quenched
two-dimensional quantum gravity. This explains the possible reason for the
considerable difference between critical exponents for the CC model and the
geometrically disordered model and may shed more light on the analytical theory
of the IQH transition. We extend our results to network models in other
symmetry classes.

categories: cond-mat.dis-nn cond-mat.mes-hall cond-mat.stat-mech hep-th


title:
Emergence, causation and storytelling: condensed matter physics and the
  limitations of the human mind

abstract:
  The physics of matter in the condensed state is concerned with problems in
which the number of constituent particles is vastly greater than can be easily
comprehended. The inherent physical limitations of the human mind are
fundamental and restrict the way in which we can interact with and learn about
the universe. This presents challenges for developing scientific explanations
that are met by emergent narratives, concepts and arguments that have a
non-trivial relationship to the underlying microphysics. By examining examples
within condensed matter physics, and also from cellular automata, I show how
such emergent narratives efficiently describe elements of reality.


title: A Stratonovich-Skorohod integral formula for Gaussian rough paths

abstract:
  Given a Gaussian process $X$, its canonical geometric rough path lift
$\mathbf{X}$, and a solution $Y$ to the rough differential equation (RDE)
$\mathrm{d}Y_{t} = V\left (Y_{t}\right ) \circ \mathrm{d} \mathbf{X}_t$, we
present a closed-form correction formula for $\int Y \circ \mathrm{d}
\mathbf{X} - \int Y \, \mathrm{d} X$, i.e. the difference between the rough and
Skorohod integrals of $Y$ with respect to $X$. When $X$ is standard Brownian
motion, we recover the classical Stratonovich-to-It{\^o} conversion formula,
which we generalize to Gaussian rough paths with finite $p$-variation, $p < 3$,
and satisfying an additional natural condition. This encompasses many familiar
examples, including fractional Brownian motion with $H > \frac{1}{3}$. To prove
the formula, we first show that the Riemann-sum approximants of the Skorohod
integral converge in $L^2(\Omega)$ by using a novel characterization of the
Cameron-Martin norm in terms of higher-dimensional Young-Stieltjes integrals.
Next, we append the approximants of the Skorohod integral with a suitable
compensation term without altering the limit, and the formula is finally
obtained after a re-balancing of terms.


title:
Magellan AO System $z'$, $Y_S$, and $L'$ Observations of the Very Wide
  650 AU HD 106906 Planetary System

abstract:
  We analyze archival data from Bailey and co-workers from the $Magellan$
adaptive optics system and present the first 0.9 $\mu$m detection ($z' =
20.3\pm0.4$ mag; $\Delta z'=13.0\pm0.4$ mag) of the 11 $M_\mathrm{Jup}$
circumbinary planet HD 106906AB b, as well as the 1 and 3.8 $\mu$m detections
of the debris disk around the binary. The disk has an east-west asymmetry in
length and surface brightness, especially at 3.8 $\mu$m where the disk appears
to be one-sided. The spectral energy distribution of b, when scaled to the
$K_S$-band photometry, is consistent with 1800 K atmospheric models without
significant dust reddening, unlike some young, very red, low-mass companions
such as CT Cha B and 1RXS 1609 B. Therefore, the suggested circumplanetary disk
of Kalas and co-workers might not contain much material, or might be closer to
face-on. Finally, we suggest that the widest ($a\gtrsim100$ AU) low mass ratio
($M_\mathrm{p}/M_\mathrm{\star} \equiv q\lesssim0.01$) companions may have
formed inside protoplanetary disks, but were later scattered by binary/planet
interactions. Such a scattering event may have occurred for HD 106906AB b with
its central binary star, but definitive proof at this time is elusive.


title: Exact Moderate Deviation Asymptotics in Streaming Data Transmission

abstract:
  In this paper, a streaming transmission setup is considered where an encoder
observes a new message in the beginning of each block and a decoder
sequentially decodes each message after a delay of $T$ blocks. In this
streaming setup, the fundamental interplay between the coding rate, the error
probability, and the blocklength in the moderate deviations regime is studied.
For output symmetric channels, the moderate deviations constant is shown to
improve over the block coding or non-streaming setup by exactly a factor of $T$
for a certain range of moderate deviations scalings. For the converse proof, a
more powerful decoder to which some extra information is fedforward is assumed.
The error probability is bounded first for an auxiliary channel and this result
is translated back to the original channel by using a newly developed
change-of-measure lemma, where the speed of decay of the remainder term in the
exponent is carefully characterized. For the achievability proof, a known
coding technique that involves a joint encoding and decoding of fresh and past
messages is applied with some manipulations in the error analysis.


title:
A Computational Model for Situated Task Learning with Interactive
  Instruction

abstract:
  Learning novel tasks is a complex cognitive activity requiring the learner to
acquire diverse declarative and procedural knowledge. Prior ACT-R models of
acquiring task knowledge from instruction focused on learning procedural
knowledge from declarative instructions encoded in semantic memory. In this
paper, we identify the requirements for designing compu- tational models that
learn task knowledge from situated task- oriented interactions with an expert
and then describe and evaluate a model of learning from situated interactive
instruc- tion that is implemented in the Soar cognitive architecture.


title:
Air Stable Doping and Intrinsic Mobility Enhancement in Monolayer
  $MoS_{2}$ by Amorphous $TiO_{x}$ Encapsulation

abstract:
  To reduce Schottky-barrier-induced contact and access resistance, and the
impact of charged impurity and phonon scattering on mobility in devices based
on 2D transition metal dichalcogenides (TMDs), considerable effort has been put
into exploring various doping techniques and dielectric engineering using
$high-\kappa$ oxides, respectively. The goal of this work is to demonstrate a
$high-\kappa$ dielectric that serves as an effective n-type charge transfer
dopant on monolayer (ML) molybdenum disulfide ($MoS_{2}$). Utilizing amorphous
titanium suboxide (ATO) as the '$high-\kappa$ dopant', we achieved a contact
resistance of ~ $180$ ${\Omega}.{\mu}m$ which is the lowest reported value for
ML $MoS_{2}$. An ON current as high as $240$ ${\mu}A/{\mu}m$ and field effect
mobility as high as $83$ $cm^2/V-s$ were realized using this doping technique.
Moreover, intrinsic mobility as high as $102$ $cm^2/V-s$ at $300$ $K$ and $501$
$cm^2/V-s$ at $77$ $K$ were achieved after ATO encapsulation which are among
the highest mobility values reported on ML $MoS_{2}$. We also analyzed the
doping effect of ATO films on ML $MoS_{2}$, a phenomenon which is absent when
stoichiometric $TiO_{2}$ is used, using ab initio density functional theory
(DFT) calculations which shows excellent agreement with our experimental
findings. Based on the interfacial-oxygen-vacancy mediated doping as seen in
the case of $high-\kappa$ ATO - ML $MoS_{2}$, we propose a mechanism for the
mobility enhancement effect observed in TMD-based devices after encapsulation
in a $high-\kappa$ dielectric environment.


title: Effects of excited state quantum phase transitions on system dynamics

abstract:
  This work is concerned with the excited state quantum phase transitions
(ESQPTs) defined in Ann.Phys. 323, 1106 (2008). In many-body models that
exhibit such transitions, the ground state quantum phase transition (QPT)
occurs in parallel with a singularity in the energy spectrum that propagates to
higher energies as the control parameter increases beyond the QPT critical
point. The analysis of the spectrum has been a main tool for the detection of
these ESQPTs. Studies of the effects of this transition on the system dynamics
are more limited. Here, we extend our previous works and show that the
evolution of an initial state with energy close to the ESQPT critical point may
be extremely slow. This result is surprising, because it may take place in
systems with long-range interactions, where the dynamics is usually expected to
be very fast. A timely example is the one-dimensional spin-1/2 model with
infinite-range Ising interaction studied in experiments with ion traps. Its
Hamiltonian has a U(2) algebraic structure. More generally, the slow dynamics
described here occurs in two-level bosonic or fermionic models with pairing
interactions and a U(v+1) Hamiltonian exhibiting a QPT between its limiting
U(v) and SO(v+1) dynamical symmetries. In this work, we compare the results for
v=1, 2, and 3.


title: Contextual object categorization with energy-based model

abstract:
  Object categorization is a hot issue of an image mining. Contextual
information between objects is one of the important semantic knowledge of an
image. However, the previous researches for an object categorization have not
made full use of the contextual information, especially the spatial relations
between objects. In addition, the object categorization methods, which
generally use the probabilistic graphical models to implement the incorporation
of contextual information with appearance of objects, are almost inevitable to
evaluate the intractable partition function for normalization. In this work, we
introduced fully-connected fuzzy spatial relations including directional,
distance and topological relations between object regions, so the spatial
relational information could be fully utilized. Then, the spatial relations
were considered as well as co-occurrence and appearance of objects by using
energy-based model, where the energy function was defined as the region-object
association potential and the configuration potential of objects. Minimizing
the energy function of whole image arrangement, we obtained the optimal label
set about the image regions and addressed the evaluation of intractable
partition function in conditional random fields. Experimental results show the
validity and reliability of this proposed method.


title:
Adaptive Content-based Routing using Subscription Subgrouping in
  Structured Overlays

abstract:
  Cyclic or general overlays may provide multiple paths between publishers and
subscribers. However, an advertisement tree and a matching subscription
activates only one path for notifications routing in publish/subscribe systems.
This poses serious challenges in handling network conditions like congestion,
and link or broker failures. Further, content-based dynamic routing of
notifications requires instantaneous updates in routing paths, which is not a
scalable option. This paper introduces a clustering approach with a bit-vector
technique for inter-cluster dynamic routing of notifications in a structured
cyclic topology that provides multiple paths between publishers and interested
subscribers. The advertisement forwarding process exploits the structured
nature of the overlay topology to generate advertisement trees of length 1
without generating duplicate messages in the advertisement forwarding process.
Issued subscriptions are divided into multiple disjoint subgropus, where each
subscription is broadcast to a cluster, which is a limited part of the
structured cyclic overlay network. We implemented novel static and
intra-cluster dynamic routing algorithms in the proposed overlay topology for
our advertisement-based publish/subscribe system, called OctopiA. We also
performed a pragmatic comparison of our two algorithms with the
state-of-the-art. Experiments on a cluster testbed show that our approach
generates fewer inter-broker messages, and is scalable.


title:
Relative Distribution of Water Clusters at Temperature (300-3000K) and
  Pressure (1-500MPa)

abstract:
  At 300-3000K and 1-500MPa, variations of relative contents for small water
clusters (H2O)n (n=1~6) were calculated by using statistical mechanical
methods. First, 9 kinds of small water clusters were selected and their
structures were optimized by using ab initio method. In the wide range of
temperature (300-3000K) and pressure (1-500MPa), their equilibrium constants of
reactions for formation of 9 kinds of water clusters were determined by using
molecular partition function. Next, changes of contents (molar fractions) as
function of temperature and pressure were estimated. The obtained results for
small water clusters can be used to interpret temperature-pressure dependency
of the average number for the hydrogen bonds in water clusters and
redistribution of the water clusters at the ultrasonic cavitation reactions.


title:
Determination of Oxygen Saturation and Photoplethysmogram from Near
  Infrared Scattering Images

abstract:
  The near infrared scattering images of human muscle include some information
on bloodstream and hemoglobin concentration according to skin depth and time.
This paper addressed a method of determining oxygen saturation and
photoplethysmogram from the near infrared (NIR) scattering images of muscle.
Depending on the modified Beer-Lambert Law and the diffuse scattering model of
muscular tissue, we determined an extinction coefficient matrix of hemoglobin
from the near infrared scattering images and analyzed distribution of oxygen
saturation of muscle with a depth from the extinction coefficient matrix. And
we determined a dynamic attenuation variation curve with respect to fragmentary
image frames sensitive to bloodstream from scattering image frames of muscle
with time and then obtained the photoplethysmogram and heart rate by Fourier
transformation and inverse transformation. This method based on the NIR
scattering images can be applied in measurement of an average oxygen saturation
and photoplethysmogram even in local region of optically heterogeneous muscle
and skin.


title: Precision optical displacement measurements using biphotons

abstract:
  We propose and examine the use of biphoton pairs, such as those created in
parametric down conversion or four-wave mixing, to enhance the precision and
the resolution of measuring optical displacements by position-sensitive
detection. We show that the precision of measuring a small optical beam
displacement with this method can be significantly enhanced by the correlation
between the two photons, given the same optical mode. The improvement is
largest if the correlations between the photons are strong, and falls off as
the biphoton correlation weakens. More surprisingly, we find that the smallest
resolvable parameter of a simple split detector scales as the inverse of the
number of biphotons for small biphoton number ("Heisenberg scaling"), because
the Fisher information diverges as the parameter to be estimated decreases in
value. One usually sees this scaling only for systems with many entangled
degrees of freedom. We discuss the transition for the split-detection scheme to
the standard quantum limit scaling for imperfect correlations as the biphoton
number is increased. An analysis of an $N$-pixel detector is also given to
investigate the benefit of using a higher resolution detector. The physical
limit of these metrology schemes is determined by the uncertainty in the birth
zone of the biphoton in the nonlinear crystal.


title: Cosmological twinlike models with multi scalar fields

abstract:
  We consider cosmological models driven by several canonical or noncanonical
scalar fields. We show how the superpotential method enables one to construct
twinlike models for a particular canonical model from some noncanonical ones.
We conclude that it is possible to construct twinlike models for multi-field
cosmological models, even when the spatial curvature is nonzero. This work
extends the discussions of [D. Bazeia and J. D. Dantas, Phys. Rev. D, 85 (2012)
067303] to cases with multi scalar fields and with non-vanished spatial
curvature, by using a different superpotential method.


title:
Behavior and finite-size effects of the sixth order cumulant in the
  three-dimensional Ising universality class

abstract:
  The high-order cumulants of conserved charges are suggested to be sensitive
observables to search for the critical point of Quantum Chromodynamics (QCD).
This has been calculated to the sixth order in experiments. Corresponding
theoretical studies on the sixth order cumulant are necessary. Based on the
universality of the critical behavior, we study the temperature dependence of
the sixth order cumulant of the order parameter using the parametric
representation of the three-dimensional Ising model, which is expected to be in
the same universality class as QCD. The density plot of the sign of the sixth
order cumulant is shown on the temperature and external magnetic field plane.
We found that at non-zero external magnetic field, when the critical point is
approached from the crossover side, the sixth order cumulant has a negative
valley. The width of the negative valley narrows with decreasing external
field. Qualitatively, the trend is similar to the result of Monte Carlo
simulation on a finite-size system. Quantitatively, the temperature of the sign
change is different. Through Monte Carlo simulation of the Ising model, we
calculated the sixth order cumulant of different sizes of systems. We discuss
the finite-size effects on the temperature at which the cumulant changes sign.


title:
Transport-entropy inequalities and curvature in discrete-space Markov
  chains

abstract:
  We show that if the random walk on a graph has positive coarse Ricci
curvature in the sense of Ollivier, then the stationary measure satisfies a W^1
transport-entropy inequality. Peres and Tetali have conjectured a stronger
consequence, that a modified log-Sobolev inequality (MLSI) should hold, in
analogy with the setting of Markov diffusions. We discuss how our entropy
interpolation approach suggests a natural attack on the MLSI conjecture.


title: Topological nodal-line fermions in ZrSiSe and ZrSiTe

abstract:
  The discovery of topological semimetal phase in three-dimensional (3D)
systems is a new breakthrough in topological material research. Dirac
nodal-line semimetal is one of the three topological semimetal phases
discovered so far; it is characterized by linear band crossing along a
line/loop, contrasted with the linear band crossing at discrete momentum points
in 3D Dirac and Weyl semimetals. The study of nodal-line semimetal is still at
initial stage; only three material systems have been verified to host nodal
line fermions until now, including PbTaSe2, PtSn 4and ZrSiS. In this letter, we
report evidence of nodal line fermions in ZrSiSe and ZrSiTe probed in de Haas -
van Alphen (dHvA) quantum oscillations. Although ZrSiSe and ZrSiTe share
similar layered structure with ZrSiS, our measurements of angular dependences
of dHvA oscillations indicate the Fermi surface (FS) enclosing Dirac nodal line
is of 2D character in ZiSiTe, in contrast with 3D-like FS in ZrSiSe and ZrSiS.
Another important property revealed in our experiment is that the nodal line
fermion density in ZrSi(S/Se) (~ 10^20-10^21 cm^-3) is much higher than the
Dirac/Weyl fermion density of any known topological materials. In addition, we
have demonstrated ZrSiSe and ZrSiTe single crystals can be thinned down to 2D
atomic thin layers through microexfoliation, which offers a promising platform
to verify the predicted 2D topological insulator in the monolayer materials
with ZrSiS-type structure


title:
Stability and instability of standing waves for a generalized Choquard
  equation with potential

abstract:
  We are going to study the standing waves for a generalized Choquard equation
with potential: $$ -i\partial_t u-\Delta
u+V(x)u=(|x|^{-\mu}\ast|u|^p)|u|^{p-2}u, \ \ \hbox{in}\ \
\mathbb{R}\times\mathbb{R}^3, $$ where $V(x)$ is a real function, $0<\mu<3$,
$2-\mu/3<p<6-\mu$ and $\ast$ stands for convolution. Under suitable assumptions
on the potential and appropriate frequency $\omega$ , the stability and
instability of the standing waves $u=e^{i \omega t}\varphi(x)$ are investigated .


title: The minimal size of graphs with given pendant-tree connectivity

abstract:
  The concept of pendant-tree $k$-connectivity $\tau_k(G)$ of a graph $G$,
introduced by Hager in 1985, is a generalization of classical
vertex-connectivity. Let $f(n,k,\ell)$ be the minimal number of edges of a
graph $G$ of order $n$ with $\tau_k(G)=\ell \ (1\leq \ell\leq n-k)$. In this
paper, we give some exact value or sharp bounds of the parameter $f(n,k,\ell)$.


title: Electron transport in real time from first-principles

abstract:
  While the vast majority of calculations reported on molecular conductance
have been based on the static non-equilibrium Green's function formalism
combined with density functional theory, in recent years a few time-depedent
approaches to transport have started to emerge. Among these, the driven
Liouville-von Neumann equation (J. Chem. Phys. 124, 214708 (2006)) is a simple
and appealing route relying on a tunable rate parameter, which has been
explored in the context of semi-empirical methods. In the present study, we
adapt this formulation to a density functional theory framework and analyze its
performance. In particular, it is implemented in an efficient all-electron DFT
code with Gaussian basis functions, suitable for quantum-dynamics simulations
of large molecular systems. At variance with the case of the tight-binding
calculations reported in the literature, we find that now the initial
perturbation to drive the system out of equilibrium plays a fundamental role in
the stability of the electron dynamics, and that the equation of motion used in
previous tight-binding implementations has to be modified to conserve the total
number of particles during time propagation. Moreover, we propose a procedure
to get rid of the dependence of the current-voltage curves on the rate
parameter. This method is employed to obtain the current-voltage characteristic
of saturated and unsaturated hydrocarbons of different lenghts, with very
promising prospects.


title:
The Numerical Approach to the Fisher's Equation via Trigonometric Cubic
  B-spline Collocation Method

abstract:
  In this study, we set up a numerical technique to get approximate solutions
of Fisher's equation which is one of the most important model equation in
population biology. We integrate the equation fully by using combination of the
trigonometric cubic B-spline functions for space variable and Crank-Nicolson
for the time integration. Numerical results have been presented to show the
accuracy of the current algorithm. We have seen that the proposed technique is
a good alternative to some existing techniques for getting solutions of the
Fisher's equation.


title:
Orbital Angular Momentum-based Space Division Multiplexing for
  High-capacity Underwater Optical Communications

abstract:
  To increase system capacity of underwater optical communications, we employ
the spatial domain to simultaneously transmit multiple orthogonal spatial
beams, each carrying an independent data channel. In this paper, we multiplex
and transmit four green orbital angular momentum (OAM) beams through a single
aperture. Moreover, we investigate the degrading effects of
scattering/turbidity, water current, and thermal gradient-induced turbulence,
and we find that thermal gradients cause the most distortions and turbidity
causes the most loss. We show systems results using two different data
generation techniques, one at 1064 nm for 10-Gbit/s/beam and one at 520 nm for
1-Gbit/s/beam, we use both techniques since present data-modulation
technologies are faster for infrared (IR) than for green. For the higher-rate
link, data is modulated in the IR, and OAM imprinting is performed in the green
using a specially-designed metasurface phase mask. For the lower rates, a green
laser diode is directly modulated. Finally, we show that inter-channel
crosstalk induced by thermal gradients can be mitigated using multi-channel
equalisation processing.