title: Massless spectrum for hybrids CFTs

abstract:
  We describe a class of theories obtained by fibering a Landau-Ginburg
orbifold over a compact Kaehler base. While such theories are often described
as phases of some GLSM, our description is independent of such an embedding. We
provide a method for computing the massless spectrum. This note is based on the
longer paper arXiv:1307.7063.


title: The Sharma-Parthasarathy stochastic two-body problem

abstract:
  We study the Sharma-Parthasarathy stochastic two-body problem introduced by
N. Sharma and H. Parthasarathy in \cite{sharma}. In particular, we focus on the
preservation of some fundamental features of the classical two-body problem
like the Hamiltonian structure and first integrals in the stochastic case.
Numerical simulations are performed which illustrate the dynamical behaviour of
the osculating elements as the semi-major axis, the eccentricity and the
pericenter. We also derive a stochastic version of Gauss's equations in the
planar case.


title:
Effects of $N(2000)\, 5/2^+$, $N(2060)\,5/2^-$, $N(2120)\,3/2^-$, and
  $N(2190)\,7/2^-$ on $K^*\Lambda$ photoproduction

abstract:
  We reinvestigate $K^*\Lambda(1116)$ photoproduction off the nucleon target,
based on an effective Lagrangian approach. We include higher nucleon resonances
such as $N(2000)\, 5/2^+$, $N(2060)\,5/2^-$, $N(2120)\,3/2^-$, and
$N(2190)\,7/2^-$, of which the data are taken from the 2012 edition of Review
of Paritcle Physics, in addition to the $t$-channel diagrams ($K$, $K^*$, and
$\kappa$), the $s$-channel nucleon, and $u$-channel hyperon($\Lambda$,
$\Sigma$, and $\Sigma^*$) contributions. We find that the $N(2120)\,3/2^-$ and
$N(2190)\,7/2^-$ resonances are essential in describing the new CLAS data for
charged $K^*$ photoproduction. On the other hand, they rarely affect for
neutral $K^*$ photoproduction.


title: Two-stage Sampled Learning Theory on Distributions

abstract:
  We focus on the distribution regression problem: regressing to a real-valued
response from a probability distribution. Although there exist a large number
of similarity measures between distributions, very little is known about their
generalization performance in specific learning tasks. Learning problems
formulated on distributions have an inherent two-stage sampled difficulty: in
practice only samples from sampled distributions are observable, and one has to
build an estimate on similarities computed between sets of points. To the best
of our knowledge, the only existing method with consistency guarantees for
distribution regression requires kernel density estimation as an intermediate
step (which suffers from slow convergence issues in high dimensions), and the
domain of the distributions to be compact Euclidean. In this paper, we provide
theoretical guarantees for a remarkably simple algorithmic alternative to solve
the distribution regression problem: embed the distributions to a reproducing
kernel Hilbert space, and learn a ridge regressor from the embeddings to the
outputs. Our main contribution is to prove the consistency of this technique in
the two-stage sampled setting under mild conditions (on separable, topological
domains endowed with kernels). For a given total number of observations, we
derive convergence rates as an explicit function of the problem difficulty. As
a special case, we answer a 15-year-old open question: we establish the
consistency of the classical set kernel [Haussler, 1999; Gartner et. al, 2002]
in regression, and cover more recent kernels on distributions, including those
due to [Christmann and Steinwart, 2010].


title:
Spectral synthesis provides 2-D videos on a 1-D screen with
  360{\deg}-visibility and mirror-immunity

abstract:
  Spatial-light-modulator (SLM)-based tunable sources have complex setups. A
simpler setup, comprising an SLM-projector and a dispersive element,
synthesizes light as effectively, based on a Superposition of Newtonian Spectra
(SNS). As a generalization of SNS, two-dimensional (2-D) grayscale videos are
spectrally encoded on a one-dimensional (1-D), translucent screen, and viewed
through another dispersive element. This Projected-Image Circumlineascopy
(PICS) produces semitransparent, rainbow-coloured, virtual 2-D videos that face
every viewer anywhere around the 1-D screen. They are invariant under
reflection of the 1-D screen in mirrors parallel to it. SNS bandwidth and PICS
image geometry are calculated using geometric optics and Dispersion Diagrams.


title:
Characterizing planetary orbits and trajectories of light in the
  Reissner-Nordstrom metric

abstract:
  Exact analytic expressions for planetary orbits and light trajectories in the
Reissner-Nordstrom geometry are presented. They are characterized in a map
specified by three dimensionless parameters for the planetary orbits, while two
dimensionless parameters are required to map the trajectories of light. Notable
differences with the corresponding orbits and trajectories in the Schwarzschild
geometry are indicated. In particular, when the energy and angular momentum of
the planet are fixed, the precession angle of the orbit decreases as the net
electric charge of the massive star or black hole increases. A similar result
also holds for the deflection angle of a light ray.


title:
Frequency-Based Patrolling with Heterogeneous Agents and Limited
  Communication

abstract:
  This paper investigates multi-agent frequencybased patrolling of
intersecting, circle graphs under conditions where graph nodes have non-uniform
visitation requirements and agents have limited ability to communicate. The
task is modeled as a partially observable Markov decision process, and a
reinforcement learning solution is developed. Each agent generates its own
policy from Markov chains, and policies are exchanged only when agents occupy
the same or adjacent nodes. This constraint on policy exchange models sparse
communication conditions over large, unstructured environments. Empirical
results provide perspectives on convergence properties, agent cooperation, and
generalization of learned patrolling policies to new instances of the task. The
emergent behavior indicates learned coordination strategies between
heterogeneous agents for patrolling large, unstructured regions as well as the
ability to generalize to dynamic variation in node visitation requirements.


title: Stochastic Gauss Equations

abstract:
  We derive the equations of celestial mechanics governing the variations of
the orbital elements under a stochastic perturbation generalizing the classical
Gauss equations. Explicit formulas are given for the semi-major axis, the
eccentricity, the inclination, the longitude of the ascending node, the
pericenter angle and the mean anomaly which are express in term of the angular
momentum vector $\textbf{H}$ per unit of mass and the energy $E$ per unit of
mass. Together, these formulas are called the \emph{stochastic Gauss equations}
and they are illustrated numerically on an example from satellite dynamics.


title:
Performance Improvement of OFDM System Using Iterative Signal Clipping
  With Various Window Techniques for PAPR Reduction

abstract:
  OFDM signals demonstrates high fluctuations termed as Peak to Average Power
Ratio (PAPR).The problem of OFDM is the frequent occurrence of high Peaks in
the time domain signal which in turn reduces the efficiency of transmit high
power amplifier.In this paper we discussed clipping and filtering technique
which is easy to implement and reduces the amount of PAPR by clipping the peak
of the maximum power signal.This technique clips the OFDM signal to a
predefined threshold and uses a filter to eliminate the out-of-band
radiation.Moreover, analysis of PAPR is given by varying different filters.The
study is focused to reduce PAPR by iterative clipping and filtering method. The
symbol error rate performances for different modulation techniques have been
countered.Each clipping noise sample is multiplied by a window
function(e.g.Hanning,Kaiser, or Hamming) to suppress the out-of-band noise.It
is shown that clipping and different filtering techniques for improvement in
the SER performance and provides further reduction in PAPR.


title: Anisotropic expansion and SNIa: an open issue

abstract:
  We review the appropriateness of using SNIa observations to detect potential
signatures of anisotropic expansion in the Universe. We focus on Union2 and
SNLS3 SNIa datasets and use the hemispherical comparison method to detect
possible anisotropic features. Unlike some previous works where non-diagonal
elements of the covariance matrix were neglected, we use the full covariance
matrix of the SNIa data, thus obtaining more realistic and not underestimated
errors. As a matter of fact, the significance of previously claimed detections
of a preferred direction in the Union2 dataset completely disappears once we
include the effects of using the full covariance matrix. Moreover, we also find
that such a a preferred direction is aligned with the orthogonal direction of
the SDSS observational plane and this suggests a clear indication that the SDSS
subsample of the Union2 dataset introduces a significant biased, making the
detected preferred direction unphysical. We thus find that current SNIa surveys
are inappropriate to test anisotropic features due to their highly
non-homogeneous angular distribution in the sky. In addition, after removal of
the highest inhomogeneous sub-samples, the number of SNIa is too low. Finally,
we take advantage of the particular distribution of SNLS SNIa sub-sample in the
SNLS3 data set, in which the observations were taken along 4 different
directions. We fit each direction independently and find consistent results at
the 1$\sigma$ level. Although the likelihoods peak at relatively different
values of $\Omega_m$,the low number of data along each direction gives rise to
large errors so that the likelihoods are sufficiently broad as to overlap
within 1$\sigma$.


title:
On Scalability of Wireless Networks: A Practical Primer for Large Scale
  Cooperation

abstract:
  An intuitive overview of the scalability of a variety of types of wireless
networks is presented. Simple heuris- tic arguments are demonstrated here for
scaling laws presented in other works, as well as for conditions not previously
considered in the literature. Unicast and multicast messages, topology,
hierarchy, and effects of reliability protocols are discussed. We show how two
key factors, bottlenecks and erasures, can often domi- nate the network scaling
behavior. Scaling of through- put or delay with the number of transmitting
nodes, the number of receiving nodes, and the file size is described.


title:
The solar diameter series of the CCD Solar Astrolabe of the
  Observat\'orio Nacional in Rio de Janeiro measured during cycle 23

abstract:
  The interest on the solar diameter variations has been primary since the
scientific revolution for different reasons: first the elliptical orbits found
by Kepler in 1609 was confirmed in the case of the Earth, and after the
intrinsic solar variability was inspected to explain the climate changes. The
CCD Solar Astrolabe of the Observat\'orio Nacional in Rio de Janeiro made daily
measurements of the solar semi-diameter from 1998 to 2009, covering most of the
cycle 23, and they are here presented with the aim to evidence the observed
variations. Some instrumental effects parametrizations have been used to
eliminate the biases appeared in morning/afternoon data reduction. The
coherence of the measurements and the influence of atmospheric effects are
presented, to discuss the reliability of the observed variations of the solar
diameter. Their amplitude is compatible with other ground-based and satellite
data recently published.


title: Matrix-free Large Scale Bayesian inference in cosmology

abstract:
  In this work we propose a new matrix-free implementation of the Wiener
sampler which is traditionally applied to high dimensional analysis when signal
covariances are unknown. Specifically, the proposed method addresses the
problem of jointly inferring a high dimensional signal and its corresponding
covariance matrix from a set of observations. Our method implements a Gibbs
sampling adaptation of the previously presented messenger approach, permitting
to cast the complex multivariate inference problem into a sequence of
uni-variate random processes. In this fashion, the traditional requirement of
inverting high dimensional matrices is completely eliminated from the inference
process, resulting in an efficient algorithm that is trivial to implement.
Using cosmic large scale structure data as a showcase, we demonstrate the
capabilities of our Gibbs sampling approach by performing a joint analysis of
three dimensional density fields and corresponding power-spectra from Gaussian
mock catalogues. These tests clearly demonstrate the ability of the algorithm
to accurately provide measurements of the three dimensional density field and
its power-spectrum and corresponding uncertainty quantification. Moreover,
these tests reveal excellent numerical and statistical efficiency which will
generally render the proposed algorithm a valuable addition to the toolbox of
large scale Bayesian inference in cosmology and astrophysics.


title: Cold dark matter heats up

abstract:
  One of the principal discoveries in modern cosmology is that standard model
particles (including baryons, leptons and photons) together comprise only 5% of
the mass-energy budget of the Universe. The remaining 95% consists of dark
energy and dark matter (DM). Consequently our picture of the universe is known
as {\Lambda}CDM, with {\Lambda} denoting dark energy and CDM cold dark matter.
{\Lambda}CDM is being challenged by its apparent inability to explain the low
density of DM measured at the centre of cosmological systems, ranging from
faint dwarf galaxies to massive clusters containing tens of galaxies the size
of the Milky Way. But before making conclusions one should carefully include
the effect of gas and stars, which were historically seen as merely a passive
component during the assembly of galaxies. We now understand that these can in
fact significantly alter the DM component, through a coupling based on rapid
gravitational potential fluctuations.


title:
Clues To The Nature of SN 2009ip from Photometric and Spectroscopic
  Evolution to Late Times

abstract:
  We present time series photometric and spectroscopic data for the transient
SN 2009ip from the start of its outburst in September 2012 until November 2013.
This data was collected primarily with the new robotic capabilities of the Las
Cumbres Observatory Global Telescope Network, a specialized facility for time
domain astrophysics, and includes supporting high-resolution spectroscopy from
the Southern Astrophysical Research Telescope, Kitt Peak National Observatory,
and Gemini Observatory. Based on our nightly photometric monitoring, we
interpret the strength and timing of fluctuations in the light curve as
interactions between fast-moving ejecta and an inhomogeneous CSM produced by
past eruptions of this massive luminous blue variable (LBV) star. Our time
series of spectroscopy in 2012 reveals that, as the continuum and narrow
H-alpha flux from CSM interactions declines, the broad component of H-alpha
persists with SN-like velocities that are not typically seen in LBVs or SN
Impostor events. At late times we find that SN 2009ip continues to decline
slowly, at <0.01 magnitudes per day, with small fluctuations in slope similar
to Type IIn supernovae (SNe IIn) or SN impostors, but no further LBV-like
activity. The late time spectrum features broad calcium lines similar to both
late time SNe and SN Impostors. In general, we find that the photometric and
spectroscopic evolution of SN 2009ip is more similar to SNe IIn than either
continued eruptions of an LBV star or SN Impostors. In this context, we discuss
the implications for episodic mass loss during the late stages of massive star
evolution.


title:
The architecture of the LkCa 15 transitional disk revealed by
  high-contrast imaging

abstract:
  We present four new epochs of Ks-band images of the young pre-transitional
disk around LkCa 15, and perform extensive forward modeling to derive the
physical parameters of the disk. We find indications of strongly anisotropic
scattering (Henyey-Greenstein g = 0.67 [-0.11,+0.18]) and a significantly
tapered gap edge ('round wall'), but see no evidence that the inner disk, whose
existence is predicted by the spectral energy distribution, shadows the outer
regions of the disk visible in our images. We marginally confirm the existence
of an offset between the disk center and the star along the line of nodes;
however, the magnitude of this offset (x = 27 [-20,+19] mas) is notably lower
than that found in our earlier H-band images (Thalmann et al. 2010).
Intriguingly, we also find, at high significance, an offset of y = 69 [-25,
+49] mas perpendicular to the line of nodes. If confirmed by future
observations, this would imply a highly elliptical -- or otherwise asymmetric
-- disk gap with an effective eccentricity of e = ~0.3. Such asymmetry would
most likely be the result of dynamical sculpting by one or more unseen planets
in the system. Finally, we find that the bright arc of scattered light we see
in direct imaging observations originates from the near side of the disk, and
appears brighter than the far side because of strong forward scattering.


title:
Suppression of the multi-azimuthal-angle instability in dense neutrino
  gas during supernova accretion phase

abstract:
  It has been recently pointed out that removing the axial symmetry in the
"multi-angle effects" associated with the neutrino-neutrino interactions for
supernova (SN) neutrinos, a new multi-azimuthal-angle (MAA) instability would
arise. In particular, for a flux ordering $F_{\nu_e} > F_{\bar\nu_e} >
F_{\nu_x}$, as expected during the SN accretion phase, this instability occurs
in the normal neutrino mass hierarchy. However, during this phase the ordinary
matter density can be larger than the neutrino one, suppressing the
self-induced conversions. At this regard, we investigate the matter suppression
of the MAA effects, performing a linearized stability analysis of the neutrino
equations of motion, in the presence of realistic SN density profiles. We
compare these results with the numerical solution of the SN neutrino non-linear
evolution equations. Assuming axially symmetric distributions of neutrino
momenta we find that the large matter term strongly inhibits the MAA effects.
In particular, the hindrance becomes stronger including realistic
forward-peaked neutrino angular distributions. As a result, in our model for a
$10.8$ $M_{\odot}$ iron-core SNe, MAA instability does not trigger any flavor
conversion during the accretion phase. Instead, for a $8.8$ $M_{\odot}$ O-Ne-Mg
core SN model, with lower matter density profile and less forward-peaked
angular distributions, flavor conversions are possible also at early times.


title: Non-classicality of positive relativistic Wigner function

abstract:
  In nonrelativistic quantum mechanics, Hudsons theorem states that a Gaussian
wavefunction is the only pure state corresponding to a positive Wigner function
(WF). We explicitly construct non Gaussian Dirac spinors with positive
relativistic WF. These pure states are coherent superpositions of particles and
antiparticles, while the existence of positive WF exclusive composed of
particles is conjectured. These observations challenge a common belief that
states with positive WF are classical or have classical analogues, and may open
new venues in relativistic quantum information.


title:
The fixation time of a strongly beneficial allele in a structured
  population

abstract:
  For a beneficial allele which enters a large unstructured population and
eventually goes to fixation, it is known that the time to fixation is
approximately $2\log(\alpha)/\alpha$ for a large selection coefficient
$\alpha$. For a population that is distributed over finitely many colonies,
with migration between these colonies, we detect various regimes of the
migration rate $\mu$ for which the fixation times have different asymptotics as
$\alpha \to \infty$. If $\mu$ is of order $\alpha$, the allele fixes (as in the
spatially unstructured case) in time $\sim 2\log(\alpha)/\alpha$. If $\mu$ is
of order $\alpha^\gamma, 0\leq \gamma \leq 1$, the fixation time is $\sim (2 +
(1-\gamma)\Delta) \log(\alpha)/\alpha$, where $\Delta$ is the number of
migration steps that are needed to reach all other colonies starting from the
colony where the beneficial allele appeared. If $\mu = 1/\log(\alpha)$, the
fixation time is $\sim (2+S)\log(\alpha)/\alpha$, where $S$ is a random time in
a simple epidemic model.
  The main idea for our analysis is to combine a new moment dual for the
process conditioned to fixation with the time reversal in equilibrium of a
spatial version of Neuhauser and Krone's ancestral selection graph.


title:
An X-ray survey of the 2Jy sample. I: is there an accretion mode
  dichotomy in radio-loud AGN?

abstract:
  We carry out a systematic study of the X-ray emission from the active nuclei
of the 0.02<z<0.7 2Jy sample, using Chandra and XMM-Newton observations. We
combine our results with those from mid-IR, optical emission line and radio
observations, and add them to those of the 3CRR sources. We show that the
low-excitation objects in our samples \redit{show signs} of radiatively
inefficient accretion. We study the effect of the jet-related emission on the
various luminosities, confirming that it is the main source of soft X-ray
emission for our sources. We also find strong correlations between the
accretion-related luminosities, and identify several sources whose optical
classification is incompatible with their accretion properties. We derive the
bolometric and jet kinetic luminosities for the samples and find a difference
in the total Eddington rate between the low and high-excitation populations,
with the former peaking at ~1 per cent and the latter at ~20 per cent
Eddington. Our results are consistent with a simple Eddington switch when the
effects of environment on radio luminosity and black hole mass calculations are
considered. The apparent independence of jet kinetic power and radiative
luminosity in the high-excitation population in our plots supports a model in
which jet production and radiatively efficient accretion are not strongly
correlated in high-excitation objects, though they have a common underlying
mechanism.


title:
The Carnegie-Spitzer-IMACS Redshift Survey of Galaxy Evolution since
  z=1.5: I. Description and Methodology and More!

abstract:
  We describe the Carnegie-Spitzer-IMACS (CSI) Survey, a wide-field, near-IR
selected spectrophotometric redshift survey with IMACS on Magellan-Baade. CSI
uses a flux-limited sample of galaxies in Spitzer IRAC 3.6micron imaging of
SWIRE fields to efficiently trace the stellar mass of average galaxies to
z~1.5. This paper provides an overview of the survey selection, observations,
and processing of the photometry and spectrophotometry. We also describe the
analysis of the data: new methods of fitting synthetic SEDs are used to derive
redshifts, stellar masses, emission line luminosities, and coarse information
on recent star-formation. Our unique methodology for analyzing low-dispersion
spectra taken with multilayer prisms in IMACS, combined with panchromatic
photometry from the ultraviolet to the IR, has yielded high quality redshifts
for 43,347 galaxies in our first 5.3 sq. degs of the SWIRE XMM-LSS field. A new
approach to assessing data quality is also described, and three different
approaches are used to estimate our redshift errors, with robust agreement.
Over the full range of 3.6micron fluxes of our selection, we find typical
redshift uncertainties of sigma_z/(1+z) < 0.015. In comparisons with previously
published spectroscopic redshifts we find scatters of sigma_z/(1+z) = 0.011 for
galaxies at 0.7< z< 0.9, and sigma_z/(1+z) = 0.014 for galaxies at 0.9< z< 1.2.
For galaxies brighter and fainter than i=23 mag, we find sigma_z/(1+z) = 0.008
and sigma_z/(1+z) = 0.022, respectively. Notably, our low-dispersion
spectroscopy and analysis yields comparable redshift uncertainties and success
rates for both red and blue galaxies, largely eliminating color-based
systematics that can seriously bias observed dependencies of galaxy evolution
on environment.


title: Law of Large Numbers for Infinite Random Matrices over a Finite Field

abstract:
  Asymptotic representation theory of general linear groups GL(n,q) over a
finite field leads to studying probability measures \rho on the group U of all
infinite uni-uppertriangular matrices over F_q, with the condition that \rho is
invariant under conjugations by arbitrary infinite matrices. Such probability
measures form an infinite-dimensional simplex, and the description of its
extreme points (in other words, ergodic measures \rho) was conjectured by Kerov
in connection with nonnegative specializations of Hall-Littlewood symmetric
functions.
  Vershik and Kerov also conjectured the following Law of Large Numbers.
Consider an n by n diagonal submatrix of the infinite random matrix drawn from
an ergodic measure coming from the Kerov's conjectural classification. The
sizes of Jordan blocks of the submatrix can be interpreted as a (random)
partition of n, or, equivalently, as a (random) Young diagram \lambda(n) with n
boxes. Then, as n goes to infinity, the rows and columns of \lambda(n) have
almost sure limiting frequencies corresponding to parameters of this ergodic
measure.
  Our main result is the proof of this Law of Large Numbers. We achieve it by
analyzing a new randomized Robinson-Schensted-Knuth (RSK) insertion algorithm
which samples random Young diagrams \lambda(n) coming from ergodic measures.
The probability weights of these Young diagrams are expressed in terms of
Hall-Littlewood symmetric functions. Our insertion algorithm is a modified and
extended version of a recent construction by Borodin and the second author
(arXiv:1305.5501). On the other hand, our randomized RSK insertion generalizes
a version of the RSK insertion introduced by Vershik and Kerov (1986) in
connection with asymptotic representation theory of symmetric groups (which is
governed by nonnegative specializations of Schur symmetric functions).


title:
A single-molecule approach to ZnO defect studies: single photons and
  single defects

abstract:
  Investigations that probe defects one at a time offer a unique opportunity to
observe properties and dynamics that are washed out of ensemble measurements.
Here we present confocal fluorescence measurements of individual defects in
Al-doped ZnO nanoparticles and undoped ZnO sputtered films that are excited
with sub-bandgap energy light. Photon correlation measurements yield both
antibunching and bunching, indicative of single-photon emission from isolated
defects that possess a metastable shelving state. The single-photon emission is
in the range 560 - 720 nm and typically exhibits two broad spectral peaks
separated by approximately 150 meV. The excited state lifetimes range from 1 -
13 ns, consistent with the finite-size and surface effects of nanoparticles and
small grains. We also observe discrete jumps in the fluorescence intensity
between a bright state and a dark state. The dwell times in each state are
exponentially distributed and the average dwell time in the bright (dark) state
does (may) depend on the power of the exciting laser. Taken together, our
measurements demonstrate the utility of a single-molecule approach to
semiconductor defect studies and highlight ZnO as a potential host material for
single-defect based applications.


title: From the Information Bottleneck to the Privacy Funnel

abstract:
  We focus on the privacy-utility trade-off encountered by users who wish to
disclose some information to an analyst, that is correlated with their private
data, in the hope of receiving some utility. We rely on a general privacy
statistical inference framework, under which data is transformed before it is
disclosed, according to a probabilistic privacy mapping. We show that when the
log-loss is introduced in this framework in both the privacy metric and the
distortion metric, the privacy leakage and the utility constraint can be
reduced to the mutual information between private data and disclosed data, and
between non-private data and disclosed data respectively. We justify the
relevance and generality of the privacy metric under the log-loss by proving
that the inference threat under any bounded cost function can be upper-bounded
by an explicit function of the mutual information between private data and
disclosed data. We then show that the privacy-utility tradeoff under the
log-loss can be cast as the non-convex Privacy Funnel optimization, and we
leverage its connection to the Information Bottleneck, to provide a greedy
algorithm that is locally optimal. We evaluate its performance on the US census
dataset.


title: The topology of quaternionic contact manifolds

abstract:
  We explore the consequences of curvature and torsion on the topology of
quaternionic contact manifolds with integrable vertical distribution. We prove
a general Myers theorem and establish a Cartan-Hadamard result for almost
qc-Einstein manifolds.


title:
Electrokinetic instability in the sharp interface limit: The
  perpendicular electric field case

abstract:
  In this paper, instability at an interface between two miscible liquids with
identical mechanical properties but different electrical conductivities is
analyzed in the presence of an electric field that is perpendicular to the
interface. A parallel electric field case was considered in a previous work
[1]. A sharp Eulerian interface is considered between the two miscible liquids.
Linear stability analysis leads to an analytic solution for the critical
condition of instability. The mechanism of instability is analyzed. Key
differences between the perpendicular and parallel electric field cases are
discussed. The effect of a microchannel geometry is studied and the relevant
non-dimensional parameters are identified.


title: On the Dynamics of Social Media Popularity: A YouTube Case Study

abstract:
  Understanding the factors that impact the popularity dynamics of social media
can drive the design of effective information services, besides providing
valuable insights to content generators and online advertisers. Taking YouTube
as case study, we analyze how video popularity evolves since upload, extracting
popularity trends that characterize groups of videos. We also analyze the
referrers that lead users to videos, correlating them, features of the video
and early popularity measures with the popularity trend and total observed
popularity the video will experience. Our findings provide fundamental
knowledge about popularity dynamics and its implications for services such as
advertising and search.


title:
Analysis of a heterogeneous social network of humans and cultural
  objects

abstract:
  Modern online social platforms enable their members to be involved in a broad
range of activities like getting friends, joining groups, posting/commenting
resources and so on. In this paper we investigate whether a correlation emerges
across the different activities a user can take part in. To perform our
analysis we focused on aNobii, a social platform with a world-wide user base of
book readers, who like to post their readings, give ratings, review books and
discuss them with friends and fellow readers. aNobii presents a heterogeneous
structure: i) part social network, with user-to-user interactions, ii) part
interest network, with the management of book collections, and iii) part
folksonomy, with books that are tagged by the users. We analyzed a complete and
anonymized snapshot of aNobii and we focused on three specific activities a
user can perform, namely her tagging behavior, her tendency to join groups and
her aptitude to compile a wishlist reporting the books she is planning to read.
In this way each user is associated with a tag-based, a group-based and a
wishlist-based profile. Experimental analysis carried out by means of
Information Theory tools like entropy and mutual information suggests that
tag-based and group-based profiles are in general more informative than
wishlist-based ones. Furthermore, we discover that the degree of correlation
between the three profiles associated with the same user tend to be small.
Hence, user profiling cannot be reduced to considering just any one type of
user activity (although important) but it is crucial to incorporate multiple
dimensions to effectively describe users preferences and behavior.

categories: cs.SI cs.CY physics.data-an physics.soc-ph


title: The Obstacle Problem on Graphs and Other Results

abstract:
  Our primary motivation is existence and uniqueness for the obstacle problem
on graphs. That is, we look for unique solutions to the problem $Lu =
\chi_{\{u>0\}}$, where $L$ is the Laplacian matrix associated to a graph, and
$u$ is a nonnegative real-valued vector with preassigned zero coordinates and
positive coordinates to be determined. In the course of solving this problem,
we make a detour into the study of Laplacian matrices themselves. First, we
present the row reduced echelon form of such matrices and determine the
invertibility of proper square submatrices. Next, we determine eigenvalues of
several simple Laplacians. In this context, we introduce a new polynomial
called the generalized characteristic polynomial that allows us to compute
(theoretically, if inefficiently)the usual characteristic polynomial for trees
by inspection of the graph. Finally, we give our solution to the obstacle
problem on graphs and discuss other components of the obstacle problem, which
we investigate in future research.


title: Cascading Failures in Power Grids - Analysis and Algorithms

abstract:
  This paper focuses on cascading line failures in the transmission system of
the power grid. Recent large-scale power outages demonstrated the limitations
of percolation- and epid- emic-based tools in modeling cascades. Hence, we
study cascades by using computational tools and a linearized power flow model.
We first obtain results regarding the Moore-Penrose pseudo-inverse of the power
grid admittance matrix. Based on these results, we study the impact of a single
line failure on the flows on other lines. We also illustrate via simulation the
impact of the distance and resistance distance on the flow increase following a
failure, and discuss the difference from the epidemic models. We then study the
cascade properties, considering metrics such as the distance between failures
and the fraction of demand (load) satisfied after the cascade (yield). We use
the pseudo-inverse of admittance matrix to develop an efficient algorithm to
identify the cascading failure evolution, which can be a building block for
cascade mitigation. Finally, we show that finding the set of lines whose
removal has the most significant impact (under various metrics) is NP-Hard and
introduce a simple heuristic for the minimum yield problem. Overall, the
results demonstrate that using the resistance distance and the pseudo-inverse
of admittance matrix provides important insights and can support the
development of efficient algorithms.


title:
Discovering functional DNA elements using population genomic
  information: A proof of concept using human mtDNA

abstract:
  Identifying the complete set of functional elements within the human genome
would be a windfall for multiple areas of biological research including
medicine, molecular biology, and evolution. Complete knowledge of function
would aid in the prioritization of loci when searching for the genetic bases of
disease or adaptive phenotypes. Because mutations that disrupt function are
disfavored by natural selection, purifying selection leaves a detectable
signature within functional elements; accordingly this signal has been
exploited through the use of genomic comparisons of distantly related species.
However, the functional complement of the genome changes extensively across
time and between lineages, therefore, evidence of the current action of
purifying selection is essential. Because the removal of deleterious mutations
by natural selection also reduces within-species genetic diversity within
functional loci, dense population genetic data have the potential to reveal
genomic elements that are currently functional. Here we assess the potential of
this approach using 16,411 human mitochondrial genomes. We show that the high
density of polymorphism in this dataset precisely delineates regions
experiencing purifying selection. Further, we show that the number of
segregating alleles at a site is strongly correlated with its divergence across
species after accounting for known mutational biases in human mtDNA. These two
measures track one another at a remarkably fine scale across many loci--a
correlation that is purely the result of natural selection. Our results
demonstrate that genetic variation has the potential to reveal exactly which
nucleotides in the genome are currently performing important functions and
likely to have deleterious fitness effects when mutated. As more complete
genomes are sequenced, similar power to reveal purifying selection may be
achievable in the human nuclear genome.


title: Bayesian inference for a flexible class of bivariate beta distributions

abstract:
  Several bivariate beta distributions have been proposed in the literature. In
particular, Olkin and Liu (2003) proposed a 3 parameter bivariate beta model,
which Arnold and Ng (2011) extend to 5 and 8 parameter models. The 3 parameter
model allows for only positive correlation, while the latter models can
accommodate both positive and negative correlation. However, these come at the
expense of a density that is mathematically intractable. The focus of this
research is on Bayesian estimation for the 5 and 8 parameter models. Since the
likelihood does not exist in closed form, we apply approximate Bayesian
computation, a likelihood free approach. Simulation studies have been carried
out for the 5 and 8 parameter cases under various priors and tolerance levels.
We apply the 5 parameter model to a real data set by allowing the model to
serve as a prior to correlated proportions of a bivariate beta binomial model.
Results and comparisons are then discussed.


title: Active Clustering with Model-Based Uncertainty Reduction

abstract:
  Semi-supervised clustering seeks to augment traditional clustering methods by
incorporating side information provided via human expertise in order to
increase the semantic meaningfulness of the resulting clusters. However, most
current methods are \emph{passive} in the sense that the side information is
provided beforehand and selected randomly. This may require a large number of
constraints, some of which could be redundant, unnecessary, or even detrimental
to the clustering results. Thus in order to scale such semi-supervised
algorithms to larger problems it is desirable to pursue an \emph{active}
clustering method---i.e. an algorithm that maximizes the effectiveness of the
available human labor by only requesting human input where it will have the
greatest impact. Here, we propose a novel online framework for active
semi-supervised spectral clustering that selects pairwise constraints as
clustering proceeds, based on the principle of uncertainty reduction. Using a
first-order Taylor expansion, we decompose the expected uncertainty reduction
problem into a gradient and a step-scale, computed via an application of matrix
perturbation theory and cluster-assignment entropy, respectively. The resulting
model is used to estimate the uncertainty reduction potential of each sample in
the dataset. We then present the human user with pairwise queries with respect
to only the best candidate sample. We evaluate our method using three different
image datasets (faces, leaves and dogs), a set of common UCI machine learning
datasets and a gene dataset. The results validate our decomposition formulation
and show that our method is consistently superior to existing state-of-the-art
techniques, as well as being robust to noise and to unknown numbers of
clusters.


title: Using Markov State Models to Study Self-Assembly

abstract:
  Markov state models (MSMs) have been demonstrated to be a powerful method for
computationally studying intramolecular processes such as protein folding and
macromolecular conformational changes. In this article, we present a new
approach to construct MSMs that is applicable to modeling a broad class of
multi-molecular assembly reactions. Distinct structures formed during assembly
are distinguished by their undirected graphs, which are defined by strong
subunit interactions. Spatial inhomogeneities of free subunits are accounted
for using a recently developed Gaussian-based signature. Simplifications to
this state identification are also investigated. The feasibility of this
approach is demonstrated on two different coarse-grained models for virus
self-assembly. We find good agreement between the dynamics predicted by the
MSMs and long, unbiased simulations, and that the MSMs can reduce overall
simulation time by orders of magnitude.


title: A remark on the gradient map

abstract:
  For a Hamiltonian action of a compact group $U$ of isometries on a compact
K\"ahler manifold $Z$ and a compatible subgroup $G$ of $U^{\mathbb{C}}$, we
prove that for any closed $G$--invariant subset $Y\subset Z$ the image of the
gradient map $\mu_{\mathfrak{p}}(Y)$ is independent of the choice of the
invariant K\"ahler form $\omega$ in its cohomology class $[\omega]$.


title:
Fluctuating Immersed Material (FIMAT) Dynamics for Fully Resolved
  Simulation of the Brownian Motion of Particles

abstract:
  Fluctuating hydrodynamics based techniques have been developed in recent
years for the simulation of Brownian motion of particles. These mesoscale
simulation tools are viable approaches for problems where molecular dynamics
simulations may be deemed expensive. We have developed a rigid constraint-based
formulation where the key idea is to assume that the entire domain is a
fluctuating fluid. Rigid motion constraints are then imposed in regions that
are occupied by rigid particles. The resulting solution gives the Brownian
motion of the particles. This approach is shown to be viable for the simulation
of long time scale diffusive behavior as well as for short time scale dynamics
by using two separate solution techniques. Test cases are reported to validate
the approach and to establish its efficacy.

categories: physics.flu-dyn cs.NA math.NA physics.comp-ph


title:
One-dimensional random attractor and rotation number of the stochastic
  damped sine-Gordon equation

abstract:
  This paper is devoted to the study of the asymptotic dynamics of the
stochastic damped sine-Gordon equation with homogeneous Neumann boundary
condition. It is shown that for any positive damping and diffusion
coefficients, the equation possesses a random attractor, and when the damping
and diffusion coefficients are sufficiently large, the random attractor is a
one-dimensional random horizontal curve regardless of the strength of noise.
Hence its dynamics is not chaotic. It is also shown that the equation has a
rotation number provided that the damping and diffusion coefficients are
sufficiently large, which implies that the solutions tend to oscillate with the
same frequency eventually and the so called frequency locking is successful.


title:
SPHGal: Smoothed Particle Hydrodynamics with improved accuracy for
  Galaxy simulations

abstract:
  We present the smoothed-particle hydrodynamics implementation SPHGal, which
combines some recently proposed improvements in GADGET. This includes a
pressure-entropy formulation with a Wendland kernel, a higher order estimate of
velocity gradients, a modified artificial viscosity switch with a modified
strong limiter, and artificial conduction of thermal energy. With a series of
idealized hydrodynamic tests we show that the pressure-entropy formulation is
ideal for resolving fluid mixing at contact discontinuities but performs
conspicuously worse at strong shocks due to the large entropy discontinuities.
Including artificial conduction at shocks greatly improves the results. In
simulations of Milky Way like disk galaxies a feedback-induced instability
develops if too much artificial viscosity is introduced. Our modified
artificial viscosity scheme prevents this instability and shows efficient shock
capturing capability. We also investigate the star formation rate and the
galactic outflow. The star formation rates vary slightly for different SPH
schemes while the mass loading is sensitive to the SPH scheme and significantly
reduced in our favored implementation. We compare the accretion behavior of the
hot halo gas. The formation of cold blobs, an artifact of simple SPH
implementations, can be eliminated efficiently with proper fluid mixing, either
by conduction and/or by using a pressure-entropy formulation.


title: Simple Molecules and Clocks

abstract:
  The precise measurement of transition frequencies in cold, trapped molecules
has applications in fundamental physics, and extremely high accuracies are
desirable. We determine suitable candidates by considering simple molecules
with a single electron, for which the external-field shift coefficients can be
calculated with high precision. Our calculations show that $\Htwop$ exhibits
particular transitions whose fractional uncertainties may reach
$2\times10^{-17}$ at room temperature. We also generalize the method of
composite frequencies, introducing tailored linear combinations of individual
transition frequencies that are free of the major systematic shifts,
independent of the strength of the external perturbing fields. By applying this
technique, the uncertainty should be reduced to the $10^{-18}$ range for both
$\Htwop$ and $\HDp$. Thus, the theoretical results demonstrate that these
molecules are of metrological relevance for future studies.


title: Synchronization of coupled stochastic systems with multiplicative noise

abstract:
  We consider the synchronization of solutions to coupled systems of the
conjugate random ordinary differential equations (RODEs) for the
$N$-Stratronovich stochastic ordinary differential equations (SODEs) with
linear multiplicative noise ($N\in \mathbb{N}$). We consider the
synchronization between two solutions and among different components of
solutions under one-sided dissipative Lipschitz conditions. We first show that
the random dynamical system generated by the solution of the coupled RODEs has
a singleton sets random attractor which implies the synchronization of any two
solutions. Moreover, the singleton sets random attractor determines a
stationary stochastic solution of the equivalently coupled SODEs. Then we show
that any solution of the RODEs converge to a solution of the averaged RODE
within any finite time interval as the coupled coefficient tends to infinity.
Our results generalize the work of two Stratronovich SODEs in \cite{9}.


title:
Dielectron Azimuthal Anisotropy at mid-rapidity in Au+Au collisions at
  $\sqrt{s_{_{NN}}} = 200$ GeV

abstract:
  We report on the first measurement of the azimuthal anisotropy ($v_2$) of
dielectrons ($e^{+}e^{-}$ pairs) at mid-rapidity from $\sqrt{s_{_{NN}}} = 200$
GeV Au+Au collisions with the STAR detector at RHIC, presented as a function of
transverse momentum ($p_T$) for different invariant-mass regions. In the mass
region $M_{ee}\!<1.1$ GeV/$c^2$ the dielectron $v_2$ measurements are found to
be consistent with expectations from $\pi^{0}$, $\eta$, $\omega$ and $\phi$
decay contributions. In the mass region $1.1\!<M_{ee}\!<2.9$ GeV/$c^2$, the
measured dielectron $v_2$ is consistent, within experimental uncertainties,
with that from the $c\bar{c}$ contributions.


title: Binary Excess Risk for Smooth Convex Surrogates

abstract:
  In statistical learning theory, convex surrogates of the 0-1 loss are highly
preferred because of the computational and theoretical virtues that convexity
brings in. This is of more importance if we consider smooth surrogates as
witnessed by the fact that the smoothness is further beneficial both
computationally- by attaining an {\it optimal} convergence rate for
optimization, and in a statistical sense- by providing an improved {\it
optimistic} rate for generalization bound. In this paper we investigate the
smoothness property from the viewpoint of statistical consistency and show how
it affects the binary excess risk. We show that in contrast to optimization and
generalization errors that favor the choice of smooth surrogate loss, the
smoothness of loss function may degrade the binary excess risk. Motivated by
this negative result, we provide a unified analysis that integrates
optimization error, generalization bound, and the error in translating convex
excess risk into a binary excess risk when examining the impact of smoothness
on the binary excess risk. We show that under favorable conditions appropriate
choice of smooth convex loss will result in a binary excess risk that is better
than $O(1/\sqrt{n})$.


title:
Optical knots and contact geometry I. From Arnol'd inequality to
  Ranada's dyons

abstract:
  Recently there had been a great deal of activity associated with various
schemes of designing both analytical and experimental methods describing
knotted structures in electrodynamics and in hydrodynamics.The majority of
works in electrodynamics were inspired by the influential paper by Ranada
(1989) and its subsequent refinements. In this work and in its companion we
analyze Ranada's results using methods of contact geometry and topology. Not
only our analysis allows us to reproduce his major results but,in addition, it
provides opportunities for considerably extending the catalog of known knot
types. Furthermore,it allows to reinterpret both the electric and magnetic
charges purely topologically thus opening the possibility of treatment of
masses and charges in Yang-Mills and gravity theories also topologically.
According to(now proven) Thurston's geometrization conjecture complements of
all knots/links in S^3 are spaces of positive, zero or negative curvature. This
means that spaces around our topological masses/charges are also curved. This
fact is essential for design of purely topological theories of gravity,
electromagnetism and strong/weak interactions


title:
In silico Proteome Cleavage Reveals Iterative Digestion Strategy for
  High Sequence Coverage

abstract:
  In the post-genome era, biologists have sought to measure the complete
complement of proteins, termed proteomics. Currently, the most effective method
to measure the proteome is with shotgun, or bottom-up, proteomics, in which the
proteome is digested into peptides that are identified followed by protein
inference. Despite continuous improvements to all steps of the shotgun
proteomics workflow, observed proteome coverage is often low; some proteins are
identified by a single peptide sequence. Complete proteome sequence coverage
would allow comprehensive characterization of RNA splicing variants and all
post translational modifications, which would drastically improve the accuracy
of biological models. There are many reasons for the sequence coverage deficit,
but ultimately peptide length determines sequence observability. Peptides that
are too short are lost because they match many protein sequences and their true
origin is ambiguous. The maximum observable peptide length is determined by
several analytical challenges. This paper explores computationally how peptide
lengths produced from several common proteome digestion methods limit
observable proteome coverage. Iterative proteome cleavage strategies are also
explored. These simulations reveal that maximized proteome coverage can be
achieved by use of an iterative digestion protocol involving multiple proteases
and chemical cleavages that theoretically allow 91.1% proteome coverage.


title: Irreducibility of Newton strata in GU(1,n-1) Shimura varieties

abstract:
  Let L be a quadratic imaginary field, inert at the rational prime p. Fix an
integer n at least 3, and let M be the moduli space (in characteristic p) of
principally polarized abelian varieties of dimension n equipped with an action
by O_L of signature of (1,n-1). We show that each Newton stratum of M, other
than the supersingular stratum, is irreducible.


title:
Convergence of eigenvalues to the support of the limiting measure in
  critical $\beta$ matrix models

abstract:
  We consider the convergence of the eigenvalues to the support of the
equilibrium measure in the $\beta$ ensemble models under a critical condition.
We show a phase transition phenomenon, namely that, with probability one, all
eigenvalues will fall in the support of the limiting spectral measure when
$\beta>1$, whereas this fails when $\beta<1$.


title: Turbulence on hyperbolic plane: the fate of inverse cascade

abstract:
  We describe ideal incompressible hydrodynamics on the hyperbolic plane which
is an infinite surface of constant negative curvature. We derive equations of
motion, general symmetries and conservation laws, and then consider turbulence
with the energy density linearly increasing with time due to action of
small-scale forcing. In a flat space, such energy growth is due to an inverse
cascade, which builds a constant part of the velocity autocorrelation function
proportional to time and expanding in scales, while the moments of the velocity
difference saturate during a time depending on the distance. For the curved
space, we analyze the long-time long-distance scaling limit, that lives in a
degenerate conical geometry, and find that the energy-containing mode linearly
growing with time is not constant in space. The shape of the velocity
correlation function indicates that the energy builds up in vortical rings of
arbitrary diameter but of width comparable to the curvature radius of the
hyperbolic plane. The energy current across scales does not increase linearly
with the scale, as in a flat space, but reaches a maximum around the curvature
radius. That means that the energy flux through scales decreases at larger
scales so that the energy is transferred in a non-cascade way, that is the
inverse cascade spills over to all larger scales where the energy pumped into
the system is cumulated in the rings. The time-saturated part of the spectral
density of velocity fluctuations contains a finite energy per unit area, unlike
in the flat space where the time-saturated spectrum behaves as k^{-5/3}.

categories: nlin.CD cond-mat.stat-mech hep-th physics.flu-dyn


title:
Roche-lobe filling factor of mass-transferring red giants - the PIONIER
  view

abstract:
  Using the PIONIER visitor instrument that combines the light of the four
Auxiliary Telescopes of ESO's Very Large Telescope Interferometer, we measure
precisely the diameters of several symbiotic and related stars: HD 352, HD
190658, V1261 Ori, ER Del, FG Ser, and AG Peg. These diameters - in the range
of 0.6 to 2.3 milli-arcseconds - are used to assess the filling factor of the
Roche lobe of the mass-losing giants and provide indications on the nature of
the ongoing mass transfer. We also provide the first spectroscopic orbit of ER
Del, based on CORAVEL and HERMES/Mercator observations. The system is found to
have an eccentric orbit with a period of 5.7 years. In the case of the
symbiotic star FG Ser, we find that the diameter is changing by 13% over the
course of 41 days, while the observations of HD 352 are indicative of an
elongation. Both these stars are found to have a Roche filling factor close to
1, as is most likely the case for HD 190658 as well, while the three other
stars have factors below 0.5-0.6. Our observations reveal the power of
interferometry for the study of interacting binary stars - the main limitation
in our conclusions being the poorly known distances of the objects.


title: Practical Calculation Scheme for Generalized Seniority

abstract:
  We propose a scheme or procedure for doing practical calculations with
generalized seniority. It reduces the total computing time by calculating and
storing in advance a set of intermediate quantities, taking advantage of the
memory capability of modern computers. The requirements and performance of the
algorithm are analyzed in detail.


title:
The Mitchell Spectrograph: Studying Nearby Galaxies with the VIRUS
  Prototype

abstract:
  The Mitchell Spectrograph (a.k.a. VIRUS-P) on the 2.7m Harlan J. Smith
telescope at McDonald Observatory is currently the largest field of view (FOV)
integral field unit (IFU) spectrograph in the world (1.7'x1.7'). It was
designed as a prototype for the highly replicable VIRUS spectrograph which
consists of a mosaic of IFUs spread over a 16' diameter FOV feeding 150
spectrographs similar to the Mitchell. VIRUS will be deployed on the 9.2 meter
Hobby-Eberly Telescope (HET) and will be used to conduct the HET Dark Energy
Experiment (HETDEX). Since seeing first light in 2007 the Mitchell Spectrograph
has been widely used, among other things, to study nearby galaxies in the local
universe where their internal structure and the spatial distribution of
different physical parameters can be studied in great detail. These
observations have provided important insight into many aspects of the physics
behind the formation and evolution of galaxies and have boosted the scientific
impact of the 2.7 meter telescope enormously. Here I review the contributions
of the Mitchell Spectrograph to the study of nearby galaxies, from the
investigation of the spatial distribution of dark matter and the properties of
supermassive black holes, to the studies of the process of star formation and
the chemical composition of stars and gas in the ISM, which provide important
information regarding the formation and evolution of these systems. I highlight
the fact that wide field integral field spectrographs on small and medium size
telescopes can be powerful cost effective tools to study the astrophysics of
galaxies. Finally I briefly discuss the potential of HETDEX for conducting
studies on nearby galaxies. The survey parameters make it complimentary and
competitive to ongoing and future surveys like SAMI and MANGA.


title:
Efficient Low Dose X-ray CT Reconstruction through Sparsity-Based MAP
  Modeling

abstract:
  Ultra low radiation dose in X-ray Computed Tomography (CT) is an important
clinical objective in order to minimize the risk of carcinogenesis. Compressed
Sensing (CS) enables significant reductions in radiation dose to be achieved by
producing diagnostic images from a limited number of CT projections. However,
the excessive computation time that conventional CS-based CT reconstruction
typically requires has limited clinical implementation. In this paper, we first
demonstrate that a thorough analysis of CT reconstruction through a Maximum a
Posteriori objective function results in a weighted compressive sensing
problem. This analysis enables us to formulate a low dose fan beam and helical
cone beam CT reconstruction. Subsequently, we provide an efficient solution to
the formulated CS problem based on a Fast Composite Splitting Algorithm-Latent
Expected Maximization (FCSA-LEM) algorithm. In the proposed method we use
pseudo polar Fourier transform as the measurement matrix in order to decrease
the computational complexity; and rebinning of the projections to parallel rays
in order to extend its application to fan beam and helical cone beam scans. The
weight involved in the proposed weighted CS model, denoted by Error Adaptation
Weight (EAW), is calculated based on the statistical characteristics of CT
reconstruction and is a function of Poisson measurement noise and rebinning
interpolation error. Simulation results show that low computational complexity
of the proposed method made the fast recovery of the CT images possible and
using EAW reduces the reconstruction error by one order of magnitude. Recovery
of a high quality 512$\times$ 512 image was achieved in less than 20 sec on a
desktop computer without numerical optimizations.


title: A unifying framework for quantifying the nature of animal interactions

abstract:
  Collective phenomena, whereby agent-agent interactions determine spatial
patterns, are ubiquitous in the animal kingdom. On the other hand, movement and
space use are also greatly influenced by the interactions between animals and
their environment. Despite both types of interaction fundamentally influencing
animal behaviour, there has hitherto been no unifying framework for the models
proposed in both areas. Here, we construct a general method for inferring
population-level spatial patterns from underlying individual movement and
interaction processes, a key ingredient in building a statistical mechanics for
ecological systems. We show that resource selection functions, as well as
several examples of collective motion models, arise as special cases of our
framework, thus bringing together resource selection analysis and collective
animal behaviour into a single theory. In particular, we focus on combining the
various mechanistic models of territorial interactions in the literature with
step selection functions, by incorporate interactions into the step selection
framework and demonstrating how to derive territorial patterns from the
resulting models. We demonstrate the efficacy of our model by application to a
population of insectivore birds in the Amazon rainforest.


title:
Polynomial Ergodic Averages Converge Rapidly: Variations on a Theorem of
  Bourgain

abstract:
  Let $L^2(X,\Sigma,\mu,\tau)$ be a measure-preserving system, with $\tau$ a
$\mathbb{Z}$-action. In this note, we prove that the ergodic averages along
integer-valued polynomials, $P(n)$, \[ M_N(f):= \frac{1}{N}\sum_{n \leq N}
\tau^{P(n)} f \] converge pointwise for $f \in L^2(X)$. We do so by proving
that, for $r>2$, the $r$-variation, $\mathcal{V}^r(M_N(f))$, extends to a
bounded operator on $L^2$. We also prove that our result is sharp, in that
$\mathcal{V}^2(M_N(f))$ is an unbounded operator on $L^2$.


title: Some Optimizations for (Maximal) Multipliers in $L^p$

abstract:
  We use Oberlin, Nazarov, and Thiele's Multi-Frequency Calder\'{o}n-Zygmund
decomposition to lower estimates on maximal multipliers in $L^p$. We also
improve on classical multiplier results of Coifman, Rubio de Francia, and
Semmes.


title:
A generalized residual technique for analyzing complex movement models
  using earth mover's distance

abstract:
  1. Complex systems of moving and interacting objects are ubiquitous in the
natural and social sciences. Predicting their behavior often requires models
that mimic these systems with sufficient accuracy, while accounting for their
inherent stochasticity. Though tools exist to determine which of a set of
candidate models is best relative to the others, there is currently no generic
goodness-of-fit framework for testing how close the best model is to the real
complex stochastic system.
  2. We propose such a framework, using a novel application of the Earth
mover's distance, also known as the Wasserstein metric. It is applicable to any
stochastic process where the probability of the model's state at time $t$ is a
function of the state at previous times. It generalizes the concept of a
residual, often used to analyze 1D summary statistics, to situations where the
complexity of the underlying model's probability distribution makes standard
residual analysis too imprecise for practical use.
  3. We give a scheme for testing the hypothesis that a model is an accurate
description of a data set. We demonstrate the tractability and usefulness of
our approach by application to animal movement models in complex, heterogeneous
environments. We detail methods for visualizing results and extracting a
variety of information on a given model's quality, such as whether there is any
inherent bias in the model, or in which situations it is most accurate. We
demonstrate our techniques by application to data on multi-species flocks of
insectivore birds in the Amazon rainforest.
  4. This work provides a usable toolkit to assess the quality of generic
movement models of complex systems, in an absolute rather than a relative
sense.


title: The magnetic moments of the proton and the antiproton

abstract:
  Recent exciting progress in the preparation and manipulation of the motional
quantum states of a single trapped proton enabled the first direct detection of
the particle's spin state. Based on this success the proton magnetic moment
$\mu_p$ was measured with ppm precision in a Penning trap with a superimposed
magnetic field inhomogeneity. An improvement by an additional factor of 1000 in
precision is possible by application of the so-called double Penning trap
technique. In a recent paper we reported the first demonstration of this method
with a single trapped proton, which is a major step towards the first direct
high-precision measurement of $\mu_p$. The techniques required for the proton
can be directly applied to measure the antiproton magnetic moment
$\mu_{\bar{p}}$. An improvement in precision of $\mu_{\bar{p}}$ by more than
three orders of magnitude becomes possible, which will provide one of the most
sensitive tests of CPT invariance. To achieve this research goal we are
currently setting up the Baryon Antibaryon Symmetry Experiment (BASE) at the
antiproton decelerator (AD) of CERN.


title: Recurrence for Pandimensional Space-Filling Functions

abstract:
  A space-filling function is a bijection from the unit line segment to the
unit square, cube, or hypercube. The function from the unit line segment is
continuous. The inverse function, while well-defined, is not continuous.
Space-filling curves, the finite approximations to space-filling functions,
have found application in global optimization, database indexing, and dimension
reduction among others. For these applications the desired transforms are
mapping a scalar to multidimensional coordinates and mapping multidimensional
coordinates to a scalar.
  Presented are recurrences which produce space-filling functions and curves of
any rank $d\ge2$ based on serpentine Hamiltonian paths on $({\bf Z}\bmod s)^d$
where $s\ge2$. The recurrences for inverse space-filling functions are also
presented. Both Peano and Hilbert curves and functions and their
generalizations to higher dimensions are produced by these recurrences. The
computations of these space-filling functions and their inverse functions are
absolutely convergent geometric series.
  The space-filling functions are constructed as limits of integer recurrences
and equivalently as non-terminating real recurrences. Scaling relations are
given which enable the space-filling functions and curves and their inverses to
extend beyond the unit area or volume and even to all of $d$-space.
  This unification of pandimensional space-filling curves facilitates
quantitative comparison of curves generated from different Hamiltonian paths.
The isotropy and performance in dimension reduction of a variety of
space-filling curves are analyzed.
  For dimension reduction it is found that Hilbert curves perform somewhat
better than Peano curves and their isotropic variants.


title: Current reversals in rapidly rotating ultra-cold Fermi gases

abstract:
  We study the equilibrium current density profiles of harmonically trapped
ultra-cold Fermi gases in quantum Hall-like states that appear when the
quasi-two-dimensional trap is set in fast rotation. The density profile of the
gas (in the rotating reference frame) consists of incompressible strips of
constant quantized density separated by compressible regions in which the
density varies. Remarkably, we find that the atomic currents flow in opposite
directions in the compressible and incompressible regions -- a prediction that
should be amenable to experimental verification.


title: Minimizing the Probability of Lifetime Ruin Under Ambiguity Aversion

abstract:
  We determine the optimal robust investment strategy of an individual who
targets at a given rate of consumption and seeks to minimize the probability of
lifetime ruin when she does not have perfect confidence in the drift of the
risky asset. Using stochastic control, we characterize the value function as
the unique classical solution of an associated Hamilton-Jacobi-Bellman (HJB)
equation, obtain feedback forms for the optimal investment and drift
distortion, and discuss their dependence on various model parameters. In
analyzing the HJB equation, we establish the existence and uniqueness of
viscosity solution using Perron's method, and then upgrade regularity by
working with an equivalent convex problem obtained via the Cole-Hopf
transformation. We show the original value function may lose convexity for a
class of parameters and the Isaacs condition may fail. Numerical examples are
also included to illustrate our results.


title: A Natural Generalization of Bounded Tree-Width and Bounded Clique-Width

abstract:
  We investigate a new width parameter, the fusion-width of a graph. It is a
natural generalization of the tree-width, yet strong enough that not only
graphs of bounded tree-width, but also graphs of bounded clique-width,
trivially have bounded fusion-width. In particular, there is no exponential
growth between tree-width and fusion-width, as is the case between tree-width
and clique-width. The new parameter gives a good intuition about the
relationship between tree-width and clique-width.


title: How Fast Can We Multiply Large Integers on an Actual Computer?

abstract:
  We provide two complexity measures that can be used to measure the running
time of algorithms to compute multiplications of long integers. The random
access machine with unit or logarithmic cost is not adequate for measuring the
complexity of a task like multiplication of long integers. The Turing machine
is more useful here, but fails to take into account the multiplication
instruction for short integers, which is available on physical computing
devices. An interesting outcome is that the proposed refined complexity
measures do not rank the well known multiplication algorithms the same way as
the Turing machine model.


title: Extension of Plurisubharmonic Functions in the Lelong Class

abstract:
  Let $X$ be an algebraic subvariety of $\mathbb C^n$ and $\bar X$ be its
closure in $\mathbb P^n.$ In their paper \cite{CGZ} Coman-Guedj-Zeriahi proved
that any plurisubharmonic function with logarithmic growth on $X$ extends to a
plurisubharmonic function with logarithmic growth on $\mathbb C^n$ when the
germs $(\bar X,a)$ in $\mathbb P^n$ are irreducible for all $a\in \bar
X\setminus X.$ In this paper we consider $X$ for which the germ $(\bar X,a)$ is
reducible for some $a\in \bar X\setminus X$ and we give a necessary and
sufficient condition for $X$ so that any plurisubharmonic function with
logarithmic growth on $X$ extends to a plurisubharmonic function with
logarithmic growth on $\mathbb C^n.$


title:
Five-list-coloring graphs on surfaces I. Two lists of size two in planar
  graphs

abstract:
  Let G be a plane graph with outer cycle C, let u,v be vertices of C and let
(L(x):x in V(G)) be a family of sets such that |L(u)|=|L(v)|=2, L(x) has at
least three elements for every vertex x of C-{u,v} and L(x) has at least five
elements for every vertex x of G-V(C). We prove a conjecture of Hutchinson that
G has a (proper) coloring f such that f(x) belongs to L(x) for every vertex x
of G. We will use this as a lemma in subsequent papers.


title: Foundation for Frequent Pattern Mining Algorithms Implementation

abstract:
  As with the development of the IT technologies, the amount of accumulated
data is also increasing. Thus the role of data mining comes into picture.
Association rule mining becomes one of the significant responsibilities of
descriptive technique which can be defined as discovering meaningful patterns
from large collection of data. The frequent pattern mining algorithms determine
the frequent patterns from a database. Mining frequent itemset is very
fundamental part of association rule mining. Many algorithms have been proposed
from last many decades including majors are Apriori, Direct Hashing and
Pruning, FP-Growth, ECLAT etc. The aim of this study is to analyze the existing
techniques for mining frequent patterns and evaluate the performance of them by
comparing Apriori and DHP algorithms in terms of candidate generation, database
and transaction pruning. This creates a foundation to develop newer algorithm
for frequent pattern mining.


title: On the Performance of Optimized Dense Device-to-Device Wireless Networks

abstract:
  We consider a D2D wireless network where $n$ users are densely deployed in a
squared planar region and communicate with each other without the help of a
wired infrastructure. For this network, we examine the 3-phase hierarchical
cooperation (HC) scheme and the 2-phase improved HC scheme based on the concept
of {\em network multiple access}. Exploiting recent results on the optimality
of treating interference as noise in Gaussian interference channels, we
optimize the achievable average per-link rate and not just its scaling law. In
addition, we provide further improvements on both the previously proposed
hierarchical cooperation schemes by a more efficient use of TDMA and spatial
reuse. Thanks to our explicit achievable rate expressions, we can compare HC
scheme with multihop routing (MR), where the latter can be regarded as the
current practice of D2D wireless networks. Our results show that the improved
and optimized HC schemes yield very significant rate gains over MR in realistic
conditions of channel propagation exponents, signal to noise ratio, and number
of users. This sheds light on the long-standing question about the real
advantage of HC scheme over MR beyond the well-known scaling laws analysis. In
contrast, we also show that our rate optimization is non-trivial, since when HC
is applied with off-the-shelf choice of the system parameters, no significant
rate gain with respect to MR is achieved. We also show that for large pathloss
exponent the sum rate is a nearly linear function of the number of users $n$ in
the range of networks of practical size. This also sheds light on a
long-standing dispute on the effective achievability of linear sum rate scaling
with HC. Finally, we notice that the achievable sum rate for large $\alpha$ is
much larger than for small $\alpha$. This suggests that HC scheme may be a very
effective approach for networks operating at mm-waves.


title:
Growth and Electrical Characterization of 2D Layered MoS2/SiC
  Heterojunctions

abstract:
  The growth and electrical characterization of a heterojunction formed between
2D layered p-MoS2 and nitrogen-doped 4H-SiC is reported. Direct growth of
p-type MoS2 films on SiC was demonstrated using chemical vapor deposition, and
the MoS2 films were found to be crystalline based on x-ray diffraction
measurements. The resulting heterojunction was found to display rectification
and current-voltage characteristics consistent with a p-n junction diode.
Capacitance voltage measurements were used to determine the built-in voltage
for the p-MoS2/n-SiC heterojunction p-n diode. The demonstration of
heterogeneous material integration between 2D layered semiconductors and 3D SiC
enables a new class of heterostructures.


title:
Probe Anomalous $tq\gamma$ couplings through Single Top Photoproduction
  at the LHC

abstract:
  In this work we study the constraints on the anomalous $tq\gamma$ ($q=u$,
$c$) couplings by photon-produced leading single top production and single top
jet associated production through the main reaction $pp\rightarrow p\gamma
p\rightarrow pt\rightarrow pW(\rightarrow\ell \nu_\ell) b+X$ and $pp\rightarrow
p\gamma p\rightarrow ptj\rightarrow pW(\rightarrow\ell \nu_\ell) bj+X$ assuming
a typical LHC multipurpose forward detectors in a model independent effective
lagrangian approach. Our results show that: for the typical detector acceptance
$0.0015<\xi_1<0.5$, $0.1<\xi_2<0.5$ and $0.0015<\xi_3<0.15$ with a luminosity
of 2 $\rm{fb}^{-1}$, the lower bounds of $\kappa_{tq\gamma}$ through leading
single top channel (single top jet channel) are 0.0096 (0.0115), 0.0162
(0.0152) and 0.0098 (0.0122), respectively, correspond to $\rm{Br}(t\rightarrow
q\gamma)\sim 3\times 10^{-5}$. With a luminosity of 200 $\rm{fb}^{-1}$, the
lower bounds of $\kappa_{tq\gamma}$ are 0.0031 (0.0034), 0.0051 (0.0047) and
0.0031(0.0038), respectively, correspond to $\rm{Br}(t\rightarrow q\gamma)\sim
4\times 10^{-6}$. We conclude that both channels can be used to detect such
anomalous $tq\gamma$ couplings and the detection sensitivity on
$\kappa_{tq\gamma}$ can be improved.


title:
On Infinite Transformations with Maximal Control of Ergodic Two-fold
  Product Powers

abstract:
  We study the rich behavior of ergodicity and conservativity of Cartesian
products of infinite measure preserving transformations. A class of
transformations is constructed such that for any subset $R\subset \mathbb Q\cap
(0,1)$ there exists $T$ in this class such that $T^p\times T^q$ is ergodic if
and only if $\frac{p}{q} \in R$. This contrasts with the finite measure
preserving case where $T^p\times T^q$ is ergodic for all nonzero $p$ and $q$ if
and only if $T\times T$ is ergodic. We also show that our class is rich in the
behavior of conservative products.
  For each positive integer $k$, a family of rank-one infinite measure
preserving transformations is constructed which have ergodic index $k$, but
infinite conservative index.


title:
Reliable Link-Based Routing Protocol for Highly Dynamic Mobile Adhoc
  Networks

abstract:
  Traditional topology-based MANET routing protocols use stateful routing which
increases the processing,communication and memory overheads. The high mobility
of nodes in MANETs makes it difficult to maintain a deterministic route. To
overcome this, stateless geographic routing protocols which ensure reliable
data delivery have been proposed. It is found that link instability can be a
major factor for unreliable data delivery. Driven by this issue, Link and
Position based Opportunistic Routing (L-POR) protocol which chooses a forwarder
based on the reception power of a node has been proposed. A back-up scheme is
also proposed to handle communication holes. Simulation results show that the
proposed protocol achieves excellent performance even under high node mobility.


title: Path integral Monte Carlo on a lattice: extended states

abstract:
  The equilibrium properties of a single quantum particle (qp) interacting with
a classical gas for a wide range of temperatures that explore the system's
behavior in the classical as well as in the quantum regime is investigated.
Both the quantum particle and atoms are restricted to the sites of a
one-dimensional lattice. A path-integral formalism is developed within the
context of the canonical ensemble in which the quantum particle is represented
by a closed, variable-step random walk on the lattice. Monte Carlo methods are
employed to determine the system's properties. For the case of a free particle,
analytical expressions for the energy, its fluctuations, and the qp-qp
correlation function are derived and compared with the Monte Carlo simulations.
To test the usefulness of the path integral formalism, the Metropolis algorithm
is employed to determine the equilibrium properties of the qp for a periodic
interaction potential, forcing the qp to occupy extended states. We consider a
striped potential in one dimension, where every other lattice site is occupied
by an atom with potential $\epsilon$, and every other lattice site is empty.
This potential serves as a stress test for the path integral formalism because
of its rapid site-to-site variation. An analytical solution was determined in
this case by utilizing Bloch's theorem due to the periodicity of the potential.
Comparisons of the potential energy, the total energy, the energy fluctuations
and the correlation function are made between the results of the Monte Carlo
simulations and the analytical calculations.


title: Color-Kinematic Duality in ABJM Theory Without Amplitude Relations

abstract:
  We explicitly show that the Bern-Carrasco-Johansson color-kinematic duality
holds at tree level through at least eight points in
Aharony-Bergman-Jafferis-Maldacena theory with gauge group SU(N) x SU(N). At
six points we give the explicit form of numerators in terms of amplitudes,
displaying the generalized gauge freedom that leads to amplitude relations.
However, at eight points no amplitude relations follow from the duality, so the
diagram numerators are fixed unique functions of partial amplitudes. We provide
the explicit amplitude-numerator decomposition and the numerator relations for
eight-point amplitudes.


title: On SH Molecules in Umbral Spectra

abstract:
  Following our predictions on detectability, very weak lines of the SH
molecules have been reported as identified in the photospheric spectrum of the
Sun. This could be the first detection of a mercapto radical in the solar
spectrum, thus placing confidence in the solar abundance of Sulfur. The
observations additionally tested the utilized theoretical band oscillator
strength. Sunspots being cooler than the photosphere are the hosts to a large
number of molecular species. However, owing to photospheric radiation scattered
into the observed umbra, the discoverers could not detect the lines of SH in
the sunspot spectrum where they are expected to show larger than the
photospheric equivalent widths (EWs in short). Detection of weak lines in
photospheric spectrum coupled with a no-detection of the relatively strong same
lines in the sunspot spectrum might cause doubts on the detection itself. The
above problem is investigated here in detail with a choice on photospheric and
sunspot models and micro-turbulence values. The new results indicate that the
predicted sunspot lines are about half intense than reported before and the
lines remain of detectable strengths. Further, a need for a laboratory
determination of oscillator strengths is felt.


title:
The equation of optimal filtering, Kalman's filter and Theorem on normal
  correlation

abstract:
  An important objective of the classical processing of stationary random
sequences under nonparametric uncertainty is the problem of filtering in case
when the distribution of the underlying signal is unknown. In this paper it is
assumed that an unknown useful signal $(S_n)_{n\ge1}$ is Markov. This allows us
to construct an estimate of the useful signal, expressed in terms of the
distribution density function of an observable random sequence $(X_n)_{n\ge1}$.
The equation of the optimal Bayesian estimation (so called equation of optimal
filtering) of such signal has been received by A.V. Dobrovidov. Our main result
is the following. It is proved that when the unobservable Markov sequence is
defined by a linear equation with the Gaussian noise, the equation of optimal
filtering coincides with the classical Kalman's filter and the conditional
expectation defined by the theorem on normal correlation.


title:
Study of Interstellar Molecular Clouds using Formaldehyde Absorption
  toward Extragalactic Radio Sources

abstract:
  We present new Very Large Array 6cm H2CO observations toward four
extragalactic radio continuum sources (B0212+735, 3C111, NRAO150, BL Lac) to
explore the structure of foreground Galactic clouds as revealed by absorption
variability. This project adds a new epoch in the monitoring observations of
the sources reported by Marscher and collaborators in the mid 1990's. Our new
observations confirm the monotonic increase in H$_2$CO absorption strength
toward NRAO150. We do not detect significant variability of our 2009 spectra
with respect to the 1994 spectra of 3C111, B0212+735 and BL Lac; however we
find significant variability of the 3C111 2009 spectrum with respect to archive
observations conducted in 1991 and 1992. Our analysis supports that changes in
absorption lines could be caused by chemical and/or geometrical gradients in
the foreground clouds, and not necessarily by small scale (~10 AU) high density
molecular clumps within the clouds.


title:
First exit time from a bounded interval for pseudo-processes driven by
  the equation $\partial/\partial t=(-1)^{N-1}\partial^{2N}/\partial x^{2N}$

abstract:
  Let $N$ be a positive integer. We consider pseudo-Brownian motion
$X=(X(t))_{t\ge 0}$ driven by the high-order heat-type equation
$\partial/\partial t=(-1)^{N-1}\partial^{2N}/\partial x^{2N}$. Let us introduce
the first exit time {\tau}ab from a bounded interval $(a,b)$ by $X$
($a,b\in\mathbb{R}$). In this paper, we provide a representation of the joint
pseudo-distribution of the vector $(\tau_{ab},X(\tau_{ab}))$ by means of
Vandermonde-like determinants. The method we use is based on the Feynman-Kac
functional related to pseudo-Brownian motion which leads to a boundary value
problem. In particular, the pseudo-distribution of the location of $X$ at time
$\tau_{ab}$, namely $X(\tau_{ab})$, admits a fine expression involving famous
Hermite interpolating polynomials.


title: Finite groups acting on higher dimensional noncommutative tori

abstract:
  For the canonical action $\alpha$ of $\operatorname{SL}_2(\mathbb{Z})$ on
2-dimensional simple rotation algebras $\mathcal{A}_\theta$, it is known that
if $F$ is a finite subgroup of $\operatorname{SL}_2(\mathbb{Z})$, the crossed
products $\mathcal{A}_\theta\rtimes_\alpha F$ are all AF algebras. In this
paper we show that this is not the case for higher dimensional noncommutative
tori. More precisely, we show that for each $n\geq 3$ there exist
noncommutative simple $\phi(n)$-dimensional tori $\mathcal{A}_\Theta$ which
admit canonical action of $\mathbb{Z}_n$ and for each odd $n\geq 7$ with
$2\phi(n)\geq n+5$ their crossed products $\mathcal{A}_\Theta\rtimes_\alpha
\mathbb{Z}_n$ are not AF (with nonzero $K_1$-groups). It is also shown that the
only possible canonical action by a finite group on a $3$-dimensional simple
torus is the flip action by $\mathbb{Z}_2$. Besides, we discuss the canonical
actions by finite groups $\mathbb{Z}_5, \mathbb{Z}_8, \mathbb{Z}_{10}$, and
$\mathbb{Z}_{12}$ on the $4$-dimensional torus of the form
$\mathcal{A}_\theta\otimes \mathcal{A}_\theta$.


title:
Combinatorial study of the Dellac configurations and the q-extended
  normalized median Genocchi numbers

abstract:
  In two recent papers (\textit{Mathematical Research
Letters,18(6):1163--1178,2011} and \textit{European J.
Combin.,33(8):1913--1918,2012}), Feigin proved that the Poincar\'e polynomials
of the degenerate flag varieties have a combinatorial interpretation through
the Dellac configurations, and related them to the $q$-extended normalized
median Genocchi numbers $\bar{c}_n(q)$ introduced by Han and Zeng, mainly by
geometric considerations. In this paper, we give combinatorial proofs of these
results by constructing statistic-preserving bijections between the Dellac
configurations and two other combinatorial models of $\bar{c}_n(q)$.


title:
Analysis of operator splitting in the non-asymptotic regime for
  nonlinear reaction-diffusion equations. Application to the dynamics of
  premixed flames

abstract:
  In this paper we mathematically characterize through a Lie formalism the
local errors induced by operator splitting when solving nonlinear
reaction-diffusion equations, especially in the non-asymptotic regime. The
non-asymptotic regime is often attained in practice when the splitting time
step is much larger than some of the scales associated with either source terms
or the diffusion operator when large gradients are present. In a series of
previous works a reduction of the asymptotic orders for a range of large
splitting time steps related to very short time scales in the nonlinear source
term has been studied, as well as that associated with large gradients but for
linearized equations. This study provides a key theoretical step forward since
it characterizes the numerical behavior of splitting errors within a more
general nonlinear framework, for which new error estimates can be derived by
coupling Lie formalism and regularizing effects of the heat equation. The
validity of these theoretical results is then assessed in the framework of two
numerical applications, a KPP-type reaction wave where the influence of
stiffness on local error estimates can be thoroughly investigated; and a much
more complex problem, related to premixed flame dynamics in the low Mach number
regime with complex chemistry and detailed transport, for which the present
theoretical study shows to provide relevant insights.


title: Comparing holographic dark energy models with statefinder

abstract:
  We apply the statefinder diagnostic to the holographic dark energy models,
including the original holographic dark energy (HDE) model, the new holographic
dark energy model, the new agegraphic dark energy (NADE) model, and the Ricci
dark energy model. In the low-redshift region the holographic dark energy
models are degenerate with each other and with the $\Lambda$CDM model in the
$H(z)$ and $q(z)$ evolutions. In particular, the HDE model is highly degenerate
with the $\Lambda$CDM model, and in the HDE model the cases with different
parameter values are also in strong degeneracy. Since the observational data
are mainly within the low-redshift region, it is very important to break this
low-redshift degeneracy in the $H(z)$ and $q(z)$ diagnostics by using some
quantities with higher order derivatives of the scale factor. It is shown that
the statefinder diagnostic $r(z)$ is very useful in breaking the low-redshift
degeneracies. By employing the statefinder diagnostic the holographic dark
energy models can be differentiated efficiently in the low-redshift region. The
degeneracy between the holographic dark energy models and the $\Lambda$CDM
model can also be broken by this method. Especially for the HDE model, all the
previous strong degeneracies appearing in the $H(z)$ and $q(z)$ diagnostics are
broken effectively. But for the NADE model, the degeneracy between the cases
with different parameter values cannot be broken, even though the statefinder
diagnostic is used. A direct comparison of the holographic dark energy models
in the $r$--$s$ plane is also made, in which the separations between the models
(including the $\Lambda$CDM model) can be directly measured in the light of the
current values $\{r_0,s_0\}$ of the models.


title:
Electric-field-tunable mechanical properties of relaxor ferroelectric
  single crystal measured by nanoindentation

abstract:
  Electric field dependent mechanical properties of relaxor ferroelectric
material Pb(Mn1/3Nb2/3)O3-PbTiO3 are investigated with the nanoindentation
technique. Giant electric-field-tunable apparent elastic modulus (up to -39%),
hardness (-9% to 20%) and energy dissipation (up to -13%) are reported. Based
on experimental data, a characterization method of electromechanical coupled
nanoindentation is proposed. In this method, an electric field tunable scaling
relationship among elastic modulus, hardness and indentation work for
ferroelectric materials can be determined. In addition, this method can be used
to obtain the electric-field-dependent elastic modulus and hardness, and avoid
the estimate of contact area in the Oliver-Pharr method. Finally, the different
effects on elastic modulus between positive and negative electric fields can be
explained by the flexoelectric effect.


title: Rojtman's theorem for normal schemes

abstract:
  We show that Rojtman's theorem holds for normal schemes: For any reduced
normal scheme of finite type over an algebraically closed field, the torsion of
the zero'th Suslin homology group agrees with the torsion of the albanese
variety (the universal object for maps to semi-abelian varieties).
  The proof uses proper hypercovers to reduce to the smooth case, which was
previously proven by Spiess-Szamuely.


title: The conical K\"ahler-Ricci flow on Fano manifolds

abstract:
  In this paper, we study the long-term behavior of the conical K\"ahler-Ricci
flow on Fano manifold $M$. First, based on our work of locally uniform
regularity for the twisted K\"ahler-Ricci flows, we obtain a long-time solution
to the conical K\"ahler-Ricci flow by limiting a sequence of these twisted
flows. Second, we study the uniform Perelman's estimates of the twisted
K\"ahler-Ricci flows. After that, we prove that the conical K\"ahler-Ricci flow
must converge to a conical K\"ahler-Einstein metric if there exists one.


title:
Observation of anomalous temperature dependence of spectrum on small
  Fermi surfaces in a BiS2-based superconductor

abstract:
  We performed an angle-resolved photoemission spectroscopy study of the
BiS2-based superconductor Nd(O,F)BiS2. Two small electron-like Fermi surfaces
around X (pi, 0) are observed, which enclose 2.4% and 1.1% of the Brillouin
zone area, respectively, corresponding to an electron doping of 7% per Bi site.
The low-energy spectrum consists of a weakly-dispersing broad hump and a
dispersive branch, which follows well the calculated band dispersion. This hump
is drastically suppressed with increasing temperature, while the dispersive
branch is essentially unaffected. The anomalous thermal effect indicates a
highly interacting electronic state, in which the superconducting pairing
develops.


title: The Generalized Statistical Complexity of PolSAR Data

abstract:
  This paper presents and discusses the use of a new feature for PolSAR
imagery: the Generalized Statistical Complexity. This measure is able to
capture the disorder of the data by means of the entropy, as well as its
departure from a reference distribution. The latter component is obtained by
measuring a stochastic distance between two models: the $\mathcal G^0$ and the
Gamma laws. Preliminary results on the intensity components of AIRSAR image of
San Francisco are encouraging.


title:
A model-free estimation for the covariate-adjusted Youden index and its
  associated cut-point

abstract:
  In medical research, continuous markers are widely employed in diagnostic
tests to distinguish diseased and non-diseased subjects. The accuracy of such
diagnostic tests is commonly assessed using the receiver operating
characteristic (ROC) curve. To summarize an ROC curve and determine its optimal
cut-point, the Youden index is popularly used. In literature, estimation of the
Youden index has been widely studied via various statistical modeling
strategies on the conditional density. This paper proposes a new model-free
estimation method, which directly estimates the covariate-adjusted cut-point
without estimating the conditional density. Consequently, covariate-adjusted
Youden index can be estimated based on the estimated cutpoint. The proposed
method formulates the estimation problem in a large margin classification
framework, which allows flexible modeling of the covariate-adjusted Youden
index through kernel machines. The advantage of the proposed method is
demonstrated in a variety of simulated experiments as well as a real
application to Pima Indians diabetes study.


title:
Toward the Standard Population Synthesis Model of the X-Ray Background:
  Evolution of X-Ray Luminosity and Absorption Functions of Active Galactic
  Nuclei Including Compton-Thick Populations

abstract:
  We present the most up-to-date X-ray luminosity function (XLF) and absorption
function of Active Galactic Nuclei (AGNs) over the redshift range from 0 to 5,
utilizing the largest, highly complete sample ever available obtained from
surveys performed with Swift/BAT, MAXI, ASCA, XMM-Newton, Chandra, and ROSAT.
The combined sample, including that of the Subaru/XMM-Newton Deep Survey,
consists of 4039 detections in the soft (0.5--2 keV) and/or hard ($>2$ keV)
band. We utilize a maximum likelihood method to reproduce the count-rate versus
redshift distribution for each survey, by taking into account the evolution of
the absorbed fraction, the contribution from Compton-thick (CTK) AGNs, and
broad band spectra of AGNs including reflection components from tori based on
the luminosity and redshift dependent unified scheme. We find that the shape of
the XLF at $z \sim 1-3$ is significantly different from that in the local
universe, for which the luminosity dependent density evolution model gives much
better description than the luminosity and density evolution model. These
results establish the standard population synthesis model of the X-Ray
Background (XRB), which well reproduces the source counts, the observed
fractions of CTK AGNs, and the spectrum of the hard XRB. The number ratio of
CTK AGNs to the absorbed Compton-thin (CTN) AGNs is constrained to be
$\approx$0.5--1.6 to produce the 20--50 keV XRB intensity within present
uncertainties, by assuming that they follow the same evolution as CTN AGNs. The
growth history of supermassive black holes is discussed based on the new AGN
bolometric luminosity function.


title: Pion masses in 2-flavor QCD with $\eta$ condensation

abstract:
  We investigate some aspects of 2-flavor QCD with $m_u\not= m_d$ at
low-energy, using the leading order chiral perturbation theory including
anomaly effects. While nothing special happens at $m_u=0$ for the fixed
$m_d\not=0$, the neutral pion mass becomes zero at two critical values of
$m_u$, between which the neutral pion field condenses, leading to a
spontaneously CP broken phase, the so-called Dashen phase. We also show that
the "topological susceptibility" in the ChPT diverges at these two critical
points. We briefly discuss a possibility that $m_u=0$ can be defined by the
vanishing the "topological susceptibility. We finally analyze the case of
$m_u=m_d=m$ with $\theta=\pi$, which is equivalent to $m_u= - m_d=-m$ with
$\theta = 0$ by the chiral rotation. In this case, the $\eta$ condensation
occurs at small $m$, violating the CP symmetry spontaneously. Deep in the
$\eta$ condensation phase, three pions become Nambu-Goldstone bosons, but they
show unorthodox behavior at small $m$ that $m_\pi^2 = O(m^2)$, which, however,
is shown to be consistent with the chiral Ward-Takahashi identities.


title:
Graviton Propagation in an Asymmetric Warped Background: Lorentz
  Violation and the Null Energy Condition

abstract:
  The graviton propagation in an asymmetric background is studied. The
background is a configuration in the six-dimensional Salam-Sezgin model, in
which a 3-form H-field turned on [JHEP 0910(2009)086]. The compact dimensions
form a cylindrical space with branes as boundaries. The background gets
asymmetry due to the H-field and violates the Lorentz symmetry. We derive the
graviton equation in this background and show that it gets massless mode
traveling with superluminal speed. A tower of K-K modes exists with a mass gap.
On the other hand, it is known that breaking the Lorentz symmetry on an
asymmetric background is constrained by the null energy condition. This no-go
theorem doesn't work well in six-dimensional space-times and by this model we
provide a counterexample for which the null energy condition is satisfied while
the Lorentz symmetry is gravitationally violated.