title: Planck 2013 results. XXIII. Isotropy and statistics of the CMB

abstract:
  The two fundamental assumptions of the standard cosmological model - that the
initial fluctuations are statistically isotropic and Gaussian - are rigorously
tested using maps of the cosmic microwave background (CMB) anisotropy from the
Planck satellite. Deviations from isotropy have been found and demonstrated to
be robust against component separation algorithm, mask choice and frequency
dependence. Many of these anomalies were previously observed in the WMAP data,
and are now confirmed at similar levels of significance (about 3 sigma).
However, we find little evidence for non-Gaussianity, with the exception of a
few statistical signatures that seem to be associated with specific anomalies.
In particular, we find that the quadrupole-octopole alignment is also connected
to a low observed variance of the CMB signal. A power asymmetry is now found to
persist to scales corresponding to about l=600, and can be described in the
low-l regime by a phenomenological dipole modulation model. However, any
primordial power asymmetry is strongly scale-dependent and does not extend to
arbitrarily small angular scales. Finally, it is plausible that some of these
features may be reflected in the angular power spectrum of the data, which
shows a deficit of power on similar scales. Indeed, when the power spectra of
two hemispheres defined by a preferred direction are considered separately, one
shows evidence for a deficit in power, while its opposite contains oscillations
between odd and even modes that may be related to the parity violation and
phase correlations also detected in the data. Although these analyses represent
a step forward in building an understanding of the anomalies, a satisfactory
explanation based on physically motivated models is still lacking.


title: Planck 2013 Results. XXIV. Constraints on primordial non-Gaussianity

abstract:
  The Planck nominal mission cosmic microwave background (CMB) maps yield
unprecedented constraints on primordial non-Gaussianity (NG). Using three
optimal bispectrum estimators, separable template-fitting (KSW), binned, and
modal, we obtain consistent values for the primordial local, equilateral, and
orthogonal bispectrum amplitudes, quoting as our final result fNL^local=
2.7+/-5.8, fNL^equil= -42+/-75, and fNL^ortho= -25+\-39 (68% CL statistical).
NG is detected in the data; using skew-C_l statistics we find a nonzero
bispectrum from residual point sources, and the ISW-lensing bispectrum at a
level expected in the LambdaCDM scenario. The results are based on
comprehensive cross-validation of these estimators on Gaussian and non-Gaussian
simulations, are stable across component separation techniques, pass an
extensive suite of tests, and are confirmed by skew-C_l, wavelet bispectrum and
Minkowski functional estimators. Beyond estimates of individual shape
amplitudes, we present model-independent, 3-dimensional reconstructions of the
Planck CMB bispectrum and thus derive constraints on early-Universe scenarios
that generate primordial NG, including general single-field models of
inflation, excited initial states (non-Bunch-Davies vacua), and
directionally-dependent vector models. We provide an initial survey of
scale-dependent feature and resonance models. These results bound both general
single-field and multi-field model parameter ranges, such as the speed of
sound, c_s \geq 0.02 (95% CL), in an effective field theory parametrization,
and the curvaton decay fraction r_D \geq 0.15 (95% CL). The Planck data
significantly limit the viable parameter space of the ekpyrotic/cyclic
scenarios. The amplitude of the 4-point function in the local model tauNL <
2800 (95% CL). These constraints represent the highest precision tests to date
of physical mechanisms for the origin of cosmic structure.


title:
Planck 2013 results. XXV. Searches for cosmic strings and other
  topological defects

abstract:
  Planck data have been used to provide stringent new constraints on cosmic
strings and other defects. We describe forecasts of the CMB power spectrum
induced by cosmic strings, calculating these from network models and
simulations using line-of-sight Boltzmann solvers. We have studied Nambu-Goto
cosmic strings, as well as field theory strings for which radiative effects are
important, thus spanning the range of theoretical uncertainty in strings
models. We have added the angular power spectrum from strings to that for a
simple adiabatic model, with the extra fraction defined as $f_{10}$ at
multipole $\ell=10$. This parameter has been added to the standard six
parameter fit using COSMOMC with flat priors. For the Nambu-Goto string model,
we have obtained a constraint on the string tension of $G\mu/c^2 < 1.5 x
10^{-7}$ and $f_{10} < 0.015$ at 95% confidence that can be improved to
$G\mu/c^2 < 1.3 x 10^{-7}$ and $f_{10} < 0.010$ on inclusion of high-$\ell$ CMB
data. For the abelian-Higgs field theory model we find, $G\mu_{AH}/c^2 < 3.2 x
10^{-7}$ and $f_{10} < 0.028$. The marginalized likelihoods for $f_{10}$ and in
the $f_{10}$--$\Omega_b h^2$ plane are also presented. We have also obtained
constraints on $f_{10}$ for models with semi-local strings and global textures
for which $G\mu/c^2 < 1.1 x 10^{-6}$. We have made complementarity searches for
the specific non-Gaussian signatures of cosmic strings, calibrating with
all-sky Planck resolution CMB maps generated from networks of
post-recombination strings. We have obtained upper limits on the string tension
at 95% confidence of $G\mu/c^2 < 8.8 x 10^{-7}$ using modal bispectrum
estimation and $G\mu/c^2 < 7.8 x 10^{-7}$ for real space searches with
Minkowski functionals. These are conservative upper bounds because only
post-recombination string contributions have been included in the non-Gaussian
analysis.


title:
Planck 2013 results. XXVI. Background geometry and topology of the
  Universe

abstract:
  Planck CMB temperature maps allow detection of large-scale departures from
homogeneity and isotropy. We search for topology with a fundamental domain
nearly intersecting the last scattering surface (comoving distance $\chi_r$).
For most topologies studied the likelihood maximized over orientation shows
some preference for multi-connected models just larger than $\chi_r$. This
effect is also present in simulated realizations of isotropic maps and we
interpret it as the alignment of mild anisotropic correlations with chance
features in a single realization; such a feature can also exist, in milder
form, when the likelihood is marginalized over orientations. Thus marginalized,
the limits on the radius $R_i$ of the largest sphere inscribed in a topological
domain (at log-likelihood-ratio -5) are: in a flat Universe, $R_i>0.9\chi_r$
for the cubic torus (cf. $R_i>0.9\chi_r$ at 99% CL for a matched-circles
search); $R_i>0.7\chi_r$ for the chimney; $R_i>0.5\chi_r$ for the slab; in a
positively curved Universe, $R_i>1.0\chi_r$ for the dodecahedron;
$R_i>1.0\chi_r$ for the truncated cube; $R_i>0.9\chi_r$ for the octahedron.
Similar limits apply to alternate topologies. We perform a Bayesian search for
an anisotropic Bianchi VII$_h$ geometry. In a non-physical setting where the
Bianchi parameters are decoupled from cosmology, Planck data favour a Bianchi
component with a Bayes factor of at least 1.5 units of log-evidence: a Bianchi
pattern is efficient at accounting for some large-scale anomalies in Planck
data. However, the cosmological parameters are in strong disagreement with
those found from CMB anisotropy data alone. In the physically motivated setting
where the Bianchi parameters are fitted simultaneously with standard
cosmological parameters, we find no evidence for a Bianchi VII$_h$ cosmology
and constrain the vorticity of such models: $(\omega/H)_0<8\times10^{-10}$ (95%
CL). [Abridged]


title: Planck 2013 results. XXVII. Doppler boosting of the CMB: Eppur si muove

abstract:
  Our velocity relative to the rest frame of the cosmic microwave background
(CMB) generates a dipole temperature anisotropy on the sky which has been well
measured for more than 30 years, and has an accepted amplitude of v/c =
0.00123, or v = 369km/s. In addition to this signal generated by Doppler
boosting of the CMB monopole, our motion also modulates and aberrates the CMB
temperature fluctuations (as well as every other source of radiation at
cosmological distances). This is an order 0.1% effect applied to fluctuations
which are already one part in roughly one hundred thousand, so it is quite
small. Nevertheless, it becomes detectable with the all-sky coverage, high
angular resolution, and low noise levels of the Planck satellite. Here we
report a first measurement of this velocity signature using the aberration and
modulation effects on the CMB temperature anisotropies, finding a component in
the known dipole direction, (l,b)=(264, 48) [deg], of 384km/s +- 78km/s (stat.)
+- 115km/s (syst.). This is a significant confirmation of the expected
velocity.


title: Planck 2013 results. XXVIII. The Planck Catalogue of Compact Sources

abstract:
  The Planck Catalogue of Compact Sources (PCCS) is the catalogue of sources
detected in the first 15 months of Planck operations, the "nominal" mission. It
consists of nine single-frequency catalogues of compact sources, both Galactic
and extragalactic, detected over the entire sky. The PCCS covers the frequency
range 30--857\,GHz with higher sensitivity (it is 90% complete at 180 mJy in
the best channel) and better angular resolution (from ~33' to ~5') than
previous all-sky surveys in this frequency band. By construction its
reliability is >80% and more than 65% of the sources have been detected at
least in two contiguous Planck channels. In this paper we present the
construction and validation of the PCCS, its contents and its statistical
characterization.


title: Planck 2013 results. XXIX. Planck catalogue of Sunyaev-Zeldovich sources

abstract:
  We describe the all-sky Planck catalogue of clusters and cluster candidates
derived from Sunyaev--Zeldovich (SZ) effect detections using the first 15.5
months of Planck satellite observations. The catalogue contains 1227 entries,
making it over six times the size of the Planck Early SZ (ESZ) sample and the
largest SZ-selected catalogue to date. It contains 861 confirmed clusters, of
which 178 have been confirmed as clusters, mostly through follow-up
observations, and a further 683 are previously-known clusters. The remaining
366 have the status of cluster candidates, and we divide them into three
classes according to the quality of evidence that they are likely to be true
clusters. The Planck SZ catalogue is the deepest all-sky cluster catalogue,
with redshifts up to about one, and spans the broadest cluster mass range from
(0.1 to 1.6) 10^{15}Msun. Confirmation of cluster candidates through comparison
with existing surveys or cluster catalogues is extensively described, as is the
statistical characterization of the catalogue in terms of completeness and
statistical reliability. The outputs of the validation process are provided as
additional information. This gives, in particular, an ensemble of 813 cluster
redshifts, and for all these Planck clusters we also include a mass estimated
from a newly-proposed SZ-mass proxy. A refined measure of the SZ Compton
parameter for the clusters with X-ray counter-parts is provided, as is an X-ray
flux for all the Planck clusters not previously detected in X-ray surveys.


title: Planck intermediate results. XIII. Constraints on peculiar velocities

abstract:
  Using \Planck\ data combined with the Meta Catalogue of X-ray detected
Clusters of galaxies (MCXC), we address the study of peculiar motions by
searching for evidence of the kinetic Sunyaev-Zeldovich effect (kSZ). By
implementing various filters designed to extract the kSZ generated at the
positions of the clusters, we obtain consistent constraints on the radial
peculiar velocity average, root mean square (rms), and local bulk flow
amplitude at different depths. For the whole cluster sample of average redshift
0.18, the measured average radial peculiar velocity with respect to the cosmic
microwave background (CMB) radiation at that redshift, i.e., the kSZ monopole,
amounts to $72 \pm 60$ km s$^{-1}$. This constitutes less than 1% of the
relative Hubble velocity of the cluster sample with respect to our local CMB
frame. While the linear $\Lambda$CDM prediction for the typical cluster radial
velocity rms at $z=0.15$ is close to 230km s$^{-1}$, the upper limit imposed by
\Planck\ data on the cluster subsample corresponds to 800 km s$^{-1}$ at 95%
confidence level, i.e., about three times higher. \Planck\ data also set strong
constraints on the local bulk flow in volumes centred on the Local Group. There
is no detection of bulk flow as measured in any comoving sphere extending to
the maximum redshift covered by the cluster sample. A blind search for bulk
flows in this sample has an upper limit of 254 km s$^{-1}$ (95% confidence
level) dominated by CMB confusion and instrumental noise, indicating that the
Universe is largely homogeneous on Gpc scales. In this context, in conjunction
with supernova observations, \Planck\ is able to rule out a large class of
inhomogeneous void models as alternatives to dark energy or modified gravity.
The \Planck\ constraints on peculiar velocities and bulk flows are thus
consistent with the $\Lambda$CDM scenario.


title:
Dramatic Evolution of the Disk-Shaped Secondary in the Orion Trapezium
  Star Theta1 Ori B1 (BM Ori): MOST Satellite Observations

abstract:
  The eclipsing binary Theta1 Orionis B1, variable star designation BM Ori, is
the faintest of the four well-known Trapezium stars at the heart of the Orion
Nebula. The primary is a B3 star (~6Msun) but the nature of the secondary
(~2Msun) has long been mysterious, since the duration and shape of primary
eclipse are inappropriate for ordinary stars. Here we report nearly continuous
photometric observations obtained with the MOST satellite over ~4 cycles of the
6.47d binary period. The light curve is of unprecedented quality, revealing a
deep, symmetric primary eclipse as well as a clear reflection effect and
secondary eclipse. In addition, there are other small disturbances, some of
which repeat at the same phase over the four cycles monitored. The shape of the
primary light curve has clearly evolved significantly over the past 40 yr.
While its overall duration and depth have remained roughly constant, the slopes
of the descent and ascent phases are significantly shallower now than in the
past and its distinctive flat-bottomed "pseudo-totality" is much less obvious
or even absent in the most recent data. We further demonstrate that the primary
eclipse was detected at X-ray wavelengths during the Chandra COUP study. The
light curve continues to be well modeled by a self-luminous and reflective
disk-shaped object seen nearly edge-on orbiting the primary. The dramatic
change in shape over four decades is modeled as an opacity variation in a
tenuous outer envelope or disk of the secondary object. We presume that the
secondary is an extremely young protostar at an earlier evolutionary phase than
can be commonly observed elsewhere in the Galaxy and that the opacity
variations observed are related to its digestion of some accreted matter over
the last 50-100 yr. Indeed, this object deserves continued observational and
theoretical attention as the youngest known eclipsing binary system.


title:
Robust-to-loss entanglement generation using a quantum plasmonic
  nanoparticle array

abstract:
  We introduce a scheme for generating entanglement between two quantum dots
using a plasmonic waveguide made from an array of metal nanoparticles. We show
that the scheme is robust to loss, enabling it to work over long distance
plasmonic nanoparticle arrays, as well as in the presence of other
imperfections such as the detuning of the energy levels of the quantum dots.
The scheme represents an alternative strategy to the previously introduced
dissipative driven schemes for generating entanglement in plasmonic systems.
Here, the entanglement is generated by using dipole-induced interference
effects and detection-based postselection. Thus, contrary to the widely held
view that loss is major problem for quantum plasmonic systems, we provide a
robust-to-loss entanglement generation scheme that could be used as a versatile
building block for quantum state engineering and control at the nanoscale.


title:
Constraints on the Intergalactic Magnetic Field from Gamma-Ray
  Observations of Blazars

abstract:
  Gamma rays from distant blazars interact with the extragalactic background
light, creating electron-positron pairs, and reducing the gamma-ray flux
measured by ground-based atmospheric Cherenkov gamma-ray telescopes. These
pairs can Compton-scatter the cosmic microwave background, creating a gamma-ray
signature observable by the Fermi Large Area Telesope (LAT). The signature is
also dependent on the intergalactic magnetic field (IGMF), since it can deflect
the pairs from our line of sight, reducing the gamma-ray emission. We present
preliminary constraints on the IGMF using Fermi-LAT and Cherenkov telescope
observations, ruling out both very large and very small values of the IGMF
strength.


title:
Constraints on dark matter annihilation from CMB observations before
  Planck

abstract:
  We compute the bounds on the dark matter (DM) annihilation cross section
using the most recent Cosmic Microwave Background measurements from WMAP9,
SPT'11 and ACT'10. We consider DM with mass in the MeV-TeV range annihilating
100% into either an e+e- or a mu+mu- pair. We consider a realistic energy
deposition model, which includes the dependence on the redshift, DM mass and
annihilation channel. We exclude the canonical thermal relic abundance cross
section (<sigma v> = 3 x 10^{-26} cm^3 s^{-1}) for DM masses below 30 GeV and
15 GeV for the e+e- and mu+mu- channels, respectively. A priori, DM
annihilating in halos could also modify the reionization history of the
Universe at late times. We implement a realistic halo model taken from results
of state-of-the-art N-body simulations and consider a mixed reionization
mechanism, consisting on reionization from DM as well as from first stars. We
find that the constraints on DM annihilation remain unchanged, even when large
uncertainties on the halo model parameters are considered.


title: Blazars in Context in the Fermi Era

abstract:
  Blazars are the most plentiful gamma-ray source at GeV energies, and despite
detailed study, there is much that is not known about these sources. In this
review I explore some recent results on blazars, including the controversy of
the "blazar sequence", the curvature in the LAT spectra, and the location along
the jet of the gamma-ray emitting region. I conclude with a discussion of
alternative modeling possibilities.


title:
Macroscopic dimension and fundamental group of manifolds with positive
  isotropic curvature

abstract:
  We prove a conjecture of Gromov's to the effect that manifolds with isotropic
curvature bounded below by 1 (after possibly rescaling) are macroscopically
1-dimensional on the scales greater than 1. As a consequence we prove that
compact manifolds with positive isotropic curvature have virtually free
fundamental groups. Our main technique is modeled on Donaldson's version of
H\"ormander technique to produce (almost) holomorphic sections which we use to
construct destabilizing sections.


title:
On the optimality of a L1/L1 solver for sparse signal recovery from
  sparsely corrupted compressive measurements

abstract:
  This short note proves the $\ell_2-\ell_1$ instance optimality of a
$\ell_1/\ell_1$ solver, i.e a variant of \emph{basis pursuit denoising} with a
$\ell_1$ fidelity constraint, when applied to the estimation of sparse (or
compressible) signals observed by sparsely corrupted compressive measurements.
The approach simply combines two known results due to Y. Plan, R. Vershynin and
E. Cand\`es.


title: Metastability bounds on the two Higgs doublet model

abstract:
  In the two Higgs doublet model, there is the possibility that the vacuum
where the universe resides in is metastable. We present the tree-level bounds
on the scalar potential parameters which have to be obeyed to prevent that
situation. Analytical expressions for those bounds are shown for the most used
potential, that with a softly broken $Z_2$ symmetry. The impact of those bounds
on the model's phenomenology is discussed in detail, as well as the importance
of the current Large Hadron Collider results in determining whether the vacuum
we live in is or is not stable. We demonstrate how the vacuum stability bounds
can be obtained for the most generic CP-conserving potential, and provide a
simple method to implement them.


title: Thin film deposition with time varying temperature

abstract:
  We study the effects of time-dependent substrate/film temperature in the
deposition of a mesoscopically thick film using a statistical model that
accounts for diffusion of adatoms without lateral neighbors whose coefficients
depend on an activation energy and temperature. Dynamic scaling with fixed
temperature is extended to predict conditions in which the temperature
variation significantly affects surface roughness scaling. It agrees with
computer simulation results for deposition of up to ${10}^4$ atomic layers and
maximal temperature changes of $30 K$, near or below the room temperature. If
the temperature decreases during the growth, the global roughness may have a
rapid growth, with effective exponents larger than 1/2 due to the
time-decreasing adatom mobility. The local roughness in small box size shows
typical evidence of anomalous scaling, with anomaly exponents depending on the
particular form of temperature decrease. If the temperature increases during
the growth, a non-monotonic evolution of the global roughness may be observed,
which is explained by the competition of kinetic roughening and the smoothing
effect of increasing diffusion lengths. The extension of the theoretical
approach to film deposition with other activation energy barriers shows that
similar conditions on temperature variation may lead to the same morphological
features. Equivalent results may also be observed by controlling the deposition
flux.


title:
The role of hyperfine coupling in magnetic and quadrupolar ordering of
  Pr3Pd20Si6

abstract:
  We study the ternary clathrate Pr3Pd20Si6 in specific heat and
AC-susceptibility measurements on a high-quality single crystal, distinguishing
antiferromagnetic (AFM) and antiferroquadrupolar (AFQ) ordering on two
sublattices of inequivalent Pr sites. The specific heat shows the direct
involvement of nuclear spin degrees of freedom in the AFM ordering, which is
well supported by our calculation of the hyperfine level scheme without
adjustable parameters. Pr3Pd20Si6 is therefore one of the rare materials where
the nuclear moments are involved in the formation of the magnetic ground state.


title:
Gaussian Quadrature of int_0^1 f(x) log^m(x) dx and int_(-1)^1 f(x)
  cos(pi*x/2) dx

abstract:
  We tabulate the abscissae and associated weights for numerical integration of
integrals with either the singular weight function (-log x)^m for exponents
m=1, 2 or 3, or the symmetric weight function cos(pi*x/2). Standard brute force
arithmetics generates explicit pairs of these values for up to 128 nodes.


title: Stability windows for proto-quark stars

abstract:
  We investigate the existence of possible stable strange matter and related
stability windows at finite temperature for different models that are generally
applied to describe quark stars, namely, the quark-mass density dependent
model, the MIT bag model and the Nambu-Jona-Lasinio model. We emphasize that,
although the limits for stable strange matter depend on a comparison with the
ground state of 56Fe, which is a zero temperature state, the quantity that has
to be used in the search for strange matter in proto-quark stars is the free
energy and we analyze stability windows up to temperatures of the order of 40
MeV. The effects of strong magnetic fields on stability windows are computed
and the resulting mass-radius relations for different stages of the proto-quark
star are analyzed.


title:
Families of efficient second order Runge-Kutta methods for the weak
  approximation of It\^o stochastic differential equations

abstract:
  Recently, a new class of second order Runge-Kutta methods for It\^o
stochastic differential equations with a multidimensional Wiener process was
introduced by R\"o{\ss}ler. In contrast to second order methods earlier
proposed by other authors, this class has the advantage that the number of
function evaluations depends only linearly on the number of Wiener processes
and not quadratically. In this paper, we give a full classification of the
coefficients of all explicit methods with minimal stage number. Based on this
classification, we calculate the coefficients of an extension with minimized
error constant of the well-known RK32 method to the stochastic case. For three
examples, this method is compared numerically with known order two methods and
yields very promising results.


title:
Diagonally drift-implicit Runge-Kutta methods of weak order one and two
  for It\^o SDEs and stability analysis

abstract:
  The class of stochastic Runge-Kutta methods for stochastic differential
equations due to R\"o{\ss}ler is considered. Coefficient families of diagonally
drift-implicit stochastic Runge-Kutta (DDISRK) methods of weak order one and
two are calculated. Their asymptotic stability as well as mean-square stability
(MS-stability) properties are studied for a linear stochastic test equation
with multiplicative noise. The stability functions for the DDISRK methods are
determined and their domains of stability are compared to the corresponding
domain of stability of the considered test equation. Stability regions are
presented for various coefficients of the families of DDISRK methods in order
to determine step size restrictions such that the numerical approximation
reproduces the characteristics of the solution process.


title:
Propagation into the heliosheath of a large-scale solar wind disturbance
  bounded by a pair of shocks

abstract:
  After the termination shock (TS) crossing, the Voyager 2 spacecraft has been
observing strong variations of the magnetic field and solar wind parameters in
the heliosheath. Anomalous cosmic rays, electrons, and galactic cosmic rays
present strong intensity fluctuations. Several works suggested that the
fluctuations might be attributed to spatial variations within the heliosheath.
Additionally, the variability of the solar wind in this region is caused by
different temporal events that occur near the Sun and propagate to the outer
heliosphere. To understand the spatial and temporal effects in the heliosheath,
it is important to study these effects separately. In this work we explore the
role of shocks as one type of temporal effects in the dynamics of the
heliosheath. Although currently plasma in the heliosheath is dominated by solar
minima conditions, with increasing solar cycle shocks associated with
transients will play an important role. We used a 3D MHD multi-fluid model of
the interaction between the solar wind and the local interstellar medium to
study the propagation of a pair of forward-reverse shocks in the supersonic
solar wind, interaction with the TS, and propagation to the heliosheath. We
found that in the supersonic solar wind the interaction region between the
shocks expands, the shocks weaken and decelerate. The fluctuation amplitudes of
the plasma parameters vary with heliocentric distance. The interaction of the
pair of shocks with the TS creates a variety of new waves and discontinuities
in the heliosheath, which produce a highly variable solar wind flow. The
collision of the forward shock with the heliopause causes a reflection of fast
magnetosonic waves inside the heliosheath.


title: Unitary groups over local rings

abstract:
  Structural properties of unitary groups over local, not necessarily
commutative, rings are developed, with applications to the computation of the
orders of these groups (when finite) and to the degrees of the irreducible
constituents of the Weil representation of a unitary group associated to a
ramified extension of finite local rings.


title:
Joint Power Adjustment and Receiver Design for Distributed Space-Time
  Coded in Cooperative MIMO Systems

abstract:
  In this paper, a joint power allocation algorithm with minimum mean-squared
error (MMSE) receiver for a cooperative Multiple-Input and Multiple-Output
(MIMO) network which employs multiple relays and a Decode-and-Forward (DF)
strategy is proposed. A Distributed Space-Time Coding (DSTC) scheme is applied
in each relay node. We present a joint constrained optimization algorithm to
determine the power allocation parameters and the MMSE receive filter parameter
vectors for each transmitted symbol in each link, as well as the channel
coefficients matrix. A Stochastic Gradient (SG) algorithm is derived for the
calculation of the joint optimization in order to release the receiver from the
massive calculation complexity for the MMSE receive filter and power allocation
parameters. The simulation results indicate that the proposed algorithm obtains
gains compared to the equal power allocation system.


title: High-Efficiency Lucky Imaging

abstract:
  Lucky Imaging is now an established observing procedure that delivers near
diffraction-limited images in the visible on ground-based telescopes up to ~2.5
m in diameter. Combined with low order adaptive optics it can deliver
resolution several times better than that of the Hubble Space Telescope. Many
images are taken at high speed as atmospheric turbulent effects appear static
on these short timescales. The sharpest images are selected, shifted and added
to give a much higher resolution than is normally possible in ground-based long
exposure time observations. The method is relatively inefficient as a
significant fraction of the frames are discarded because of their relatively
poor quality. This paper shows that a new Lucky Imaging processing method
involving selection in Fourier space can substantially improve the selection
percentages. The results show that high resolution images with a large
isoplanatic patch size may be obtained routinely both with conventional Lucky
Imaging and with the new Lucky Fourier method. Other methods of improving the
sensitivity of the method to faint reference stars are also described.


title:
A Geometric Approach to Joint Inversion with Applications to Contaminant
  Source Zone Characterization

abstract:
  This paper presents a new joint inversion approach to shape-based inverse
problems. Given two sets of data from distinct physical models, the main
objective is to obtain a unified characterization of inclusions within the
spatial domain of the physical properties to be reconstructed. Although our
proposed method generally applies to many types of inversion problems, the main
motivation here is to characterize subsurface contaminant source-zones by
processing down gradient hydrological data and cross-gradient electrical
resistance tomography (ERT) observations. Inspired by Newton's method for
multi-objective optimization, we present an iterative inversion scheme that
suggests taking descent steps that can simultaneously reduce both data-model
misfit terms. Such an approach, however, requires solving a non-smooth convex
problem at every iteration, which is computationally expensive for a
pixel-based inversion over the whole domain. Instead, we employ a parametric
level set (PaLS) technique that substantially reduces the number of underlying
parameters, making the inversion computationally tractable. The performance of
the technique is examined and discussed through the reconstruction of source
zone architectures that are representative of dense non-aqueous phase liquid
(DNAPL) contaminant release in a statistically homogenous sandy aquifer. In
these examples, the geometric configuration of the DNAPL mass is considered
along with additional information about its spatial variability within the
contaminated zone, such as the identification of low and high saturation
regions. Comparison of the reconstructions with the true DNAPL architectures
highlights the superior performance of the model-based technique and joint
inversion scheme.


title: One-norm geometric quantum discord under decoherence

abstract:
  Geometric quantum discord is a well-defined measure of quantum correlation if
Schatten 1-norm (trace norm) is adopted as a distance measure. Here, we
analytically investigate the dynamical behavior of the 1-norm geometric quantum
discord under the effect of decoherence. By starting from arbitrary
Bell-diagonal mixed states under Markovian local noise, we provide the decays
of the quantum correlation as a function of the decoherence parameters. In
particular, we show that the 1-norm geometric discord exhibits the possibility
of double sudden changes and freezing behavior during its evolution. For
non-trivial Bell-diagonal states under simple Markovian channels, these are new
features that are in contrast with the Schatten 2-norm (Hilbert-Schmidt)
geometric discord. The necessary and sufficient conditions for double sudden
changes as well as their exact locations in terms of decoherence probabilities
are provided. Moreover, we illustrate our results by investigating decoherence
in quantum spin chains in the thermodynamic limit.


title:
Linking dynamical and functional properties of intrinsically bursting
  neurons

abstract:
  Several studies have shown that bursting neurons can encode information in
the number of spikes per burst: As the stimulus varies, so does the length of
individual bursts. The represented stimuli, however, vary substantially among
different sensory modalities and different neurons. The goal of this paper is
to determine which kind of stimulus features can be encoded in burst length,
and how those features depend on the mathematical properties of the underlying
dynamical system. We show that the initiation and termination of each burst is
triggered by specific stimulus features whose temporal characteristsics are
determined by the types of bifurcations that initiate and terminate firing in
each burst. As only a few bifurcations are possible, only a restricted number
of encoded features exists. Here we focus specifically on describing parabolic,
square-wave and elliptic bursters. We find that parabolic bursters, whose
firing is initiated and terminated by saddle-node bifurcations, behave as
prototypical integrators: Firing is triggered by depolarizing stimuli, and
lasts for as long as excitation is prolonged. Elliptic bursters, contrastingly,
constitute prototypical resonators, since both the initiating and terminating
bifurcations possess well-defined oscillation time scales. Firing is therefore
triggered by stimulus stretches of matching frequency and terminated by a
phase-inversion in the oscillation. The behavior of square-wave bursters is
somewhat intermediate, since they are triggered by a fold bifurcation of cycles
of well-defined frequency but are terminated by a homoclinic bifurcation
lacking an oscillating time scale. These correspondences show that stimulus
selectivity is determined by the type of bifurcations. We also demonstrate that
additional biological properties that do not modify the bifurcation structure
play a minor role in stimulus encoding.


title:
Structure, microstructure and hydrogen storage properties of melt-spun
  V55Ti21Cr17Fe7 and V55Ti21Mn17Fe7

abstract:
  The hydrogen sorption performance of V55Ti21Cr17Fe7 and V55Ti21Mn17Fe7 alloys
and their ribbons were evaluated by pressure composition temperature tests.
Their hydrogen absorption kinetic properties were studied through hydrogen
absorption curves. The crystallographic structures and microstructure of these
alloys and ribbons before hydrogen absorption and after hydrogen desorption PCT
tests were identified by Xray diffraction and Scanning electron microscopy
analysis, respectively. Hydrogen storage characteristics of such materials were
investigated by volumetric method using Sieverts type apparatus and gravimetric
method with suspension balance.


title: A theory of regularity structures

abstract:
  We introduce a new notion of "regularity structure" that provides an
algebraic framework allowing to describe functions and / or distributions via a
kind of "jet" or local Taylor expansion around each point. The main novel idea
is to replace the classical polynomial model which is suitable for describing
smooth functions by arbitrary models that are purpose-built for the problem at
hand. In particular, this allows to describe the local behaviour not only of
functions but also of large classes of distributions.
  We then build a calculus allowing to perform the various operations
(multiplication, composition with smooth functions, integration against
singular kernels) necessary to formulate fixed point equations for a very large
class of semilinear PDEs driven by some very singular (typically random) input.
This allows, for the first time, to give a mathematically rigorous meaning to
many interesting stochastic PDEs arising in physics. The theory comes with
convergence results that allow to interpret the solutions obtained in this way
as limits of classical solutions to regularised problems, possibly modified by
the addition of diverging counterterms. These counterterms arise naturally
through the action of a "renormalisation group" which is defined canonically in
terms of the regularity structure associated to the given class of PDEs.
  As an example of a novel application, we solve the long-standing problem of
building a natural Markov process that is symmetric with respect to the (finite
volume) measure describing the $\Phi^4_3$ Euclidean quantum field theory. It is
natural to conjecture that the Markov process built in this way describes the
Glauber dynamic of 3-dimensional ferromagnets near their critical temperature.


title:
The matrix sign function for solving surface wave problems in
  homogeneous and laterally periodic elastic half-spaces

abstract:
  The matrix sign function is shown to provide a simple and direct method to
derive some fundamental results in the theory of surface waves in anisotropic
materials. It is used to establish a shortcut to the basic formulas of the
Barnett-Lothe integral formalism and to obtain an explicit solution of the
algebraic matrix Riccati equation for the surface impedance. The matrix sign
function allows the Barnett-Lothe formalism to be readily generalized for the
problem of finding the surface wave speed in a periodically inhomogeneous
half-space with material properties that are independent of depth. No partial
wave solutions need to be found; the surface wave dispersion equation is
formulated instead in terms of blocks of the matrix sign function of i times
the Stroh matrix.


title: Corrigendum: Improved He~I Emissivities in the Case B Approximation

abstract:
  Errors were discovered in our recent calculations of HeI emissivities (Porter
et al. 2012; arXiv:1206.4115). This corrigendum discusses the errors and
reports corrected emissivities.


title: Ultrasonic Attenuation and Speed of Sound of Cornstarch Suspensions

abstract:
  The goal of this study is to contribute to the physics underlying the
material properties of suspensions that exhibit shear thickening through the
ultrasonic characterization of suspensions of cornstarch in a density-matched
solution. Ultrasonic measurements at frequencies in the range of 4 to 8 MHz of
the speed of sound and the frequency-dependent attenuation properties are
reported for concentrations of cornstarch in a density-matched aqueous (cesium
chloride brine) suspension, ranging up to 40% cornstarch. The speed of sound is
found to range from 1483 +/- 10 m/s in pure brine to 1765 +/- 9 m/s in the 40%
cornstarch suspension. The bulk modulus of a granule of cornstarch is inferred
to be (1.2 +/- 0.1) X 10^{10} Pa. The attenuation coefficient at 5 MHz
increases from essentially zero in brine to 12.0 +/- 1.2 dB/cm at 40%
cornstarch.


title:
A Lyapunov approach to Robust and Adaptive finite time stabilization of
  integrator chains with bounded uncertainty

abstract:
  In this paper, we present Lyapunov-based robust and adaptive controllers for
the finite time stabilization of a perturbed chain of integrators with bounded
uncertainties. The proposed controllers can be designed for integrator chains
of any arbitrary length. The uncertainty bounds are known in the robust control
problem whereas they are unknown in the adaptive control problem. Both
controllers are developed from a class of finite time stabilization controllers
for pure integrator chains. Lyapunov-based design permits to calculate upper
bound on convergence time.


title: Path following for a target point attached to a unicycle type vehicle

abstract:
  In this article, we address the control problem of unicycle path following,
using a rigidly attached target point. The initial path following problem has
been transformed into a reference trajectory following problem, using saturated
control laws and a geometric characterization hypothesis, which links the
curvature of the path to be followed with the target point. The proposed
controller allows global stabilization without restrictions on initial
conditions. The effectiveness of this controller is illustrated through
simulations.


title:
Renormalization of the second-order QCD with arbitrary chromomagnetic
  factor and quark self-interactions

abstract:
  In this work, the renormalization of the second-order QCD is analyzed at
one-loop level, including an arbitrary chromomagnetic factor and quark
self-interactions, which are mass dimension four operators in this framework.
The model is shown to be renormalizable for any value of the chromomagnetic
factor $\kappa$ in the validity region of the perturbative expansion, and Dirac
QCD is recovered in the $\kappa=2$ case with vanishing self-interaction
couplings.


title:
Global tracking for an underactuated ships with bounded feedback
  controllers

abstract:
  In this paper, we present a global state feedback tracking controller for
underactuated surface marine vessels. This controller is based on saturated
control inputs and, under an assumption on the reference trajectory, the
closed-loop system is globally asymptotically stable (GAS). It has been
designed using a 3 Degree of Freedom benchmark vessel model used in marine
engineering. The main feature of our controller is the boundedness of the
control inputs, which is an essential consideration in real life. In absence of
velocity measurements, the controller works and remains stable with observers
and can be used as an output feedback controller. Simulation results
demonstrate the effectiveness of this method.


title:
Low-Rank STAP Algorithm for Airborne Radar Based on Basis-Function
  Approximation

abstract:
  In this paper, we develop a novel reduced-rank space-time adaptive processing
(STAP) algorithm based on adaptive basis function approximation (ABFA) for
airborne radar applications. The proposed algorithm employs the well-known
framework of the side-lobe canceller (SLC) structure and consists of selected
sets of basis functions that perform dimensionality reduction and an adaptive
reduced-rank filter. Compared to traditional reduced-rank techniques, the
proposed scheme works on an instantaneous basis, selecting the best suited set
of basis functions at each instant to minimize the squared error. Furthermore,
we derive stochastic gradient (SG) and recursive least squares (RLS) algorithm
for efficiently implementing the proposed ABFA scheme. Simulations for a
clutter-plus-jamming suppression application show that the proposed STAP
algorithm outperforms the state-of-the-art reduced-rank schemes in convergence
and tracking at significantly lower complexity.


title:
Nonadiabatic transitions in exactly solvable quantum mechanical
  multichannel model: role of level curvature and counterintuitive behavior

abstract:
  We derive an exact solution of an explicitly time-dependent multichannel
model of quantum mechanical nonadiabatic transitions. In the limit N >>1, where
N is the number of states, we find that the survival probability of the
initially populated state remains finite despite an almost arbitrary choice of
a large number of parameters. This observation proves that quantum mechanical
nonadiabatic transitions among a large number of states can effectively keep
memory about the initial state of the system. This property can lead to a
strongly non-ergodic behavior even in the thermodynamic limit of some systems
with a broad distribution of coupling constants and the lack of energy
conservation.

categories: quant-ph cond-mat.mes-hall math-ph math.MP


title:
Monolayer curvature stabilizes nanoscale raft domains in mixed lipid
  bilayers

abstract:
  According to the lipid raft hypothesis, biological lipid membranes are
laterally heterogeneous and filled with nanoscale ordered "raft" domains, which
are believed to play an important role for the organization of proteins in
membranes. However, the mechanisms stabilizing such small rafts are not clear,
and even their existence is sometimes questioned. Here we report the
observation of raft-like structures in a coarse-grained molecular model for
multicomponent lipid bilayers. On small scales, our membranes demix into a
liquid ordered (lo) and a liquid disordered (ld) phase. On large scales, phase
separation is suppressed and gives way to a microemulsion-type state that
contains nanometer size lo domains in a ld environment. Furthermore, we
introduce a mechanism that generates rafts of finite size by a coupling between
monolayer curvature and local composition. We show that mismatch between the
spontaneous curvatures of monolayers in the lo and ld phase induces elastic
interactions, which reduce the line tension between the lo and ld phase and can
stabilize raft domains with a characteristic size of the order of a few
nanometers. Our findings suggest that rafts in multicomponent bilayers might be
closely related to the modulated ripple phase in one-component bilayers.


title: The Physics of crypto-nonlocality

abstract:
  In 2003, Leggett introduced his model of crypto-nonlocality based on
considerations on the reality of the photon polarization. In this note, we
prove that, contrary to hints in subsequent literature, crypto-nonlocality does
not follow naturally from the postulate that polarization is a realistic
variable. More explicitly, consider physical theories where: a)
faster-than-light communication is impossible; b) all physical photon states
have a definite polarization; and c) given two separate photons, if we measure
one of them and post-select on the result, the measurement statistics of the
remaining system correspond to a photon state. We show that the outcomes of any
two-photon polarization experiment in these theories must follow the statistics
generated by measuring a separable two-qubit quantum state. Consequently, in
such experiments any instance of entanglement detection -and not necessarily a
Leggett inequality violation- can be regarded as a refutation of this class of
theories.


title: Yukawa Unification Predictions with effective "Mirage" Mediation

abstract:
  In this letter we analyze the consequences, for the LHC, of gauge and third
family Yukawa coupling unification with a particular set of boundary conditions
defined at the GUT scale, which we characterize as effective "mirage"
mediation. We perform a global chi-squared analysis including the observables
M_W, M_Z, G_F, alpha_em, alpha_s(M_Z), M_top, m_b(m_b), M_tau, BR(B -> X_s
gamma), BR(B_s -> mu^+ mu^-) and M_{h}. The fit is performed in the MSSM in
terms of 10 GUT scale parameters, while tanb and mu are fixed at the weak
scale. We find good fits to the low energy data and a SUSY spectrum which is
dramatically different than previously studied in the context of Yukawa
unification.


title: From configurations to branched configurations and beyond

abstract:
  We propose here a geometric and topological setting for the study of
branching effects arising in various fields of research, e.g. in statistical
mechanics and turbulence theory. We describe various aspects that appear key
points to us, and finish with a limit of such a construction which stand in the
dynamics on probability spaces where it seems that branching effects can be
fully studied without any adaptation of the framework.


title:
Target-point based path following controller for a car-type vehicle
  using bounded controls

abstract:
  In this paper, we have studied the control problem of target-point based path
following for car-type vehicles. This special path following task arises from
the needs of vision based guidance systems, where a given target-point located
ahead of the vehicle, in the visual range of the camera, must follow a
specified path. A solution to this problem is developed through a non linear
transformation of the path following problem into a reference trajectory
tracking problem, by modeling the target point as a virtual vehicle. Bounded
feedback laws must be then used on the real vehicle's angular acceleration and
the virtual vehicle's velocity, to achieve stability. The resulting controller
is globally asymptotically stable with respect and the proof is demonstrated
using Lyapunov based arguments and a bootstrap argument. The effectiveness of
this controller has been illustrated through simulations.


title: Limiting Shapes in Two-Dimensional Ising Ferromagnets

abstract:
  We consider an Ising model on a square grid with ferromagnetic spin-spin
interactions spanning beyond nearest neighbors. Starting from initial states
with a single unbounded interface separating ordered phases, we investigate the
evolution of the interface subject to zero-temperature spin-flip dynamics. We
consider an interface which is initially (i) the boundary of the quadrant, or
(ii) the boundary of a semi-infinite stripe. In the former case the interface
recedes from its original location in a self-similar diffusive manner. After a
re-scaling by t^{1/2}, the shape of the interface becomes more and more
deterministic; we determine this limiting shape analytically and verify our
predictions numerically. The semi-infinite stripe acquires a stationary shape
resembling a finger, and this finger translates along its axis. We compute the
limiting shape and the velocity of the Ising finger.

categories: cond-mat.stat-mech math-ph math.MP math.PR


title: Kinetic plasma turbulence in the fast solar wind measured by Cluster

abstract:
  The k-filtering technique and wave polarization analysis are applied to
Cluster magnetic field data to study plasma turbulence at the scale of the ion
gyroradius in the fast solar wind. Waves are found propagating in directions
nearly perpendicular to the background magnetic field at such scales. The
frequencies of these waves in the solar wind frame are much smaller than the
proton gyro-frequency. After the wave vector ${\bf k}$ is determined at each
spacecraft frequency $f_{sc}$, wave polarization property is analyzed in the
plane perpendicular to ${\bf k}$. Magnetic fluctuations have
  $\delta B_\perp>\delta B_\parallel$ (here the $\parallel$ and $\perp$ refer
to the background magnetic field ${\bf B}_0$). The wave magnetic field has
right-handed polarization at propagation angles $\theta_{\bf kB}<90^\circ$ and
$>90^\circ$. The magnetic field in the plane perpendicular to ${\bf B}_0$
however has no clear sense of a dominant polarization but local rotations. We
discuss the merits and limitations of linear kinetic Aflv\'en waves (KAWs) and
coherent Alfv\'en vortices in the interpretation of the data. We suggest that
the fast solar wind turbulence may be populated with KAWs, small scale current
sheets and Alfv\'en vortices at ion kinetic scales.


title:
How to measure the spatial correlations in disordered
  Berezinski-Kosterlitz-Thouless transition ?

abstract:
  The Berezinski-Kosterlitz-Thouless transition is a unique two dimensional
phase transition, separating two phases with exponentially and power-law
decaying correlations, respectively. In disordered systems, these correlations
propagate along favorable paths, with the transition marking the point where
global coherence is lost. Here we propose an experimental method to probe
locally these particular paths in superconducting thin films, which exhibit
this transition, and demonstrate theoretically that close to the transition the
coherence propagate along a ramified network, reminiscent of a percolation
transition. We suggest and calculate experimentally accessible quantities that
can shed light on the spatial correlations in the system as it approaches the
critical point.


title: Intrinsic Chirality of Multipartite Graphs

abstract: We classify which complete multipartite graphs are intrinsically chiral.


title:
Discovering Semantic Spatial and Spatio-Temporal Outliers from Moving
  Object Trajectories

abstract:
  Several algorithms have been proposed for discovering patterns from
trajectories of moving objects, but only a few have concentrated on outlier
detection. Existing approaches, in general, discover spatial outliers, and do
not provide any further analysis of the patterns. In this paper we introduce
semantic spatial and spatio-temporal outliers and propose a new algorithm for
trajectory outlier detection. Semantic outliers are computed between regions of
interest, where objects have similar movement intention, and there exist
standard paths which connect the regions. We show with experiments on real data
that the method finds semantic outliers from trajectory data that are not
discovered by similar approaches.


title: Reverse epitaxy of Ge: ordered and facetted surface patterns

abstract:
  Normal incidence ion irradiation at elevated temperatures, when amorphization
is prevented, induces novel nanoscale patterns of crystalline structures on
elemental semiconductors by a reverse epitaxial growth mechanism: on Ge
surfaces irradiation at temperatures above the recrystallization temperature of
250{\deg}C leads to self-organized patterns of inverse pyramids. Checkerboard
patterns with fourfold symmetry evolve on the Ge (100) surface, whereas on the
Ge (111) surface, isotropic patterns with a sixfold symmetry emerge. After high
fluence irradiations these patterns exhibit well developed facets. A
deterministic nonlinear continuum equation accounting for the effective surface
currents due to an Ehrlich-Schwoebel barrier for diffusing vacancies reproduces
remarkably well our experimental observations.


title: Bounds on the Number of Huffman and Binary-Ternary Trees

abstract:
  Huffman coding is a widely used method for lossless data compression because
it optimally stores data based on how often the characters occur in Huffman
trees. An $n$-ary Huffman tree is a connected, cycle-lacking graph where each
vertex can have either $n$ "children" vertices connecting to it, or 0 children.
Vertices with 0 children are called \textit{leaves}. We let $h_n(q)$ represent
the total number of $n$-ary Huffman trees with $q$ leaves. In this paper, we
use a recursive method to generate upper and lower bounds on $h_n(q)$ and get
$h_2(q) \approx (0.1418532)(1.7941471)^q+(0.0612410)(1.2795491)^q$ for $n=2$.
This matches the best results achieved by Elsholtz, Heuberger, and Prodinger in
August 2011. Our approach reveals patterns in Huffman trees that we used in our
analysis of the Binary-Ternary (BT) trees we created. Our research opens a
completely new door in data compression by extending the study of Huffman trees
to BT trees. Our study of BT trees paves the way for designing data-specific
trees, minimizing possible wasted storage space from Huffman coding. We prove a
recursive formula for the number of BT trees with $q$ leaves. Furthermore, we
provide analysis and further proofs to reach numeric bounds. Our discoveries
have broad applications in computer data compression. These results also
improve graphical representations of protein sequences that facilitate in-depth
genome analysis used in researching evolutionary patterns.


title:
Lipschitz minimality of the multiplication maps of unit complex,
  quaternion and octonion numbers

abstract:
  We prove that the multiplication maps $\mathbb{s}^n \times \mathbb{s}^n
\rightarrow \mathbb{s}^n$ ($n = 1, 3, 7$) for unit complex, quaternion and
octonion numbers are, up to isometries of domain and range, the unique
Lipschitz constant minimizers in their homotopy classes. Other geometrically
natural maps, such as projections of Hopf fibrations, have already been shown
to be, up to isometries, the unique Lipschitz constant minimizers in their
homotopy classes, and it is suspected that this may hold true for all
Riemannian submersions of compact homogeneous spaces.


title:
Sufficient sparseness conditions for G^2 to be (\Delta+1)-choosable,
  when \Delta\ge5

abstract:
  We determine the list chromatic number of the square of a graph $\chil(G^2)$
in terms of its maximum degree $\Delta$ when its maximum average degree,
denoted $\mad(G)$, is sufficiently small. For $\Delta\ge 6$, if
$\mad(G)<2+\frac{4\Delta-8}{5\Delta+2}$, then $\chil(G^2)=\Delta+1$. In
particular, if $G$ is planar with girth $g\ge 7+\frac{12}{\Delta-2}$, then
$\chil(G^2)=\Delta+1$. Under the same conditions, $\chil^i(G)=\Delta$, where
$\chil^i$ is the list injective chromatic number.


title:
The genericity of the infinitesimal Lipschitz condition for
  hypersurfaces

abstract:
  We continue the development of the theory of infinitesimal Lipschitz
equivalence, showing the genericity of the condition for families of
hypersurfaces with isolated singularities.


title:
Non-empirical Study of Superconductivity in Alkali-doped Fullerides
  Based on Density Functional Theory for Superconductors

abstract:
  We apply the density functional theory for superconductors (SCDFT) based on
the local-density approximation (LDA) to alkali-doped fullerides A3C60 with the
face-centered cubic structure. We evaluate the superconducting transition
temperature (Tc) from first principles considering energy dependence of
electron-phonon coupling, the mass renormalization, and the retardation effect.
The calculated Tc=7.5, 9.0 and 15.7 K for A=K, Rb, Cs are approximately 60 %
smaller than the experimentally observed values. Our results strongly suggest
necessity to go beyond the framework of the Migdal-Eliashberg theory based on
the LDA.


title: The first k-regular subgraph is large

abstract:
  We prove that for sufficiently large k, there exist $0\le\sigma_k\le\eps_k\to
0$ as $k\to\infty$, such that asymptotically almost surely the first k-regular
subgraph appeared in the random graph process where one edge is added at a time
has size between $(1-\eps_k)|\K_k|$ and $(1-\sigma_k)|\K_k|$, where $\K_k$
denotes the $k$-core of the graph.


title: The Generalized DMPK equation revisited: A systematic derivation

abstract:
  The Generalized Dorokov-Mello-Pereyra-Kumar (DMPK) equation has recently been
used to obtain a family of very broad and highly asymmetric conductance
distributions for three dimensional disordered conductors. However, there are
two major criticisms of the derivation of the Generalized DMPK equation: (1)
certain eigenvector correlations were neglected based on qualitative arguments
that can not be valid for all disorder, and (2) the repulsion between two
closely spaced eigenvalues were not rigorously governed by symmetry
considerations. In this work we show that it is possible to address both
criticisms by including the eigenvalue and eigenvector correlations in a
systematic and controlled way. It turns out that the added correlations
determine the evolution of the Jacobian, without affecting the evaluation of
the conductance distributions. They also guarantee the symmetry requirements.
In addition, we obtain an exact relationship between the eigenvectors and the
Lyapunov exponents leading to a sum rule for the latter at all disorder.


title: Weil representations over finite fields and Shintani lift

abstract:
  Let Sp_V(F) be the group of isometries of a symplectic vector space V over a
finite field F of odd cardinality. The group Sp_V(F) possesses distinguished
representations--- the Weil representations. We know that they are compatible
with base change in the sense of Shintani for a finite extension F'/F. The
result is also true for the group of similitudes of V.


title: Moments of the Riesz distribution

abstract:
  This article derives the first two moments of the two versions of the Riesz
distribution in the terms of their characteristic functions.


title:
Nonparametric Forecasts of the CMB Angular Power Spectra for the Planck
  Mission

abstract:
  The Planck mission, designed for making measurements of the cosmic microwave
background (CMB) radiation with unprecedented accuracy and angular resolution,
is expected to release its first data set in the near future. For the first
time in the CMB history, extensive measurements of the CMB polarization will be
made available for the entire sky. Such precise and rich data are expected to
contain a great wealth of information about the Universe. The information in
the CMB data is conveniently represented in terms of angular power spectra for
temperature and polarization. A proper estimation of these CMB power spectra
from data is the first step in making inferences about the Universe and, in
particular, cosmological parameters that govern the Universe. In this paper, we
provide forecasts for the $TT$, $EE$, and $TE$ angular power spectra for the
Planck mission. Our forecasts are made using synthetic data based on the
best-fit $\Lambda$CDM model while conforming to the characteristics and
parameters of the Planck mission. We have analysed such synthetic data sets
using a nonparametric function estimation formalism that is otherwise
asymptotically model-independent. Indeed, the power spectra estimated from such
synthetic data turn out to be sufficiently close to the corresponding
$\Lambda$CDM spectra. Our analysis further indicates that the three angular
power spectra are determined sufficiently well for $2 \le l \lesssim l_{max}$,
where $l_{max} = 2500 {($TT$),} 1377 {($EE$), and} 1727 {($TE$)}$ respectively.
A signature of reionization is evident in the $EE$ and $TE$ power spectra in
the form of a bump at low $l$s ...


title: The Kato-Ponce Inequality

abstract:
  In this article we develop a simplistic approach to revisit the classical
Kato-Ponce inequality, which is also known as 'fractional Leibniz rule.' As a
consequence, we derive the validity of this inequality even in quasi-Banach
spaces $L^p$ for $p<1$ with a certain restrictions on the indices. Also, we
display the sharpness of this restriction by means of a counter-example.
Finally, we also prove a multi-parameter variant of the inequality, which
allows for partial fractional derivatives on $R^n$.


title: Node-Based Learning of Multiple Gaussian Graphical Models

abstract:
  We consider the problem of estimating high-dimensional Gaussian graphical
models corresponding to a single set of variables under several distinct
conditions. This problem is motivated by the task of recovering transcriptional
regulatory networks on the basis of gene expression data {containing
heterogeneous samples, such as different disease states, multiple species, or
different developmental stages}. We assume that most aspects of the conditional
dependence networks are shared, but that there are some structured differences
between them. Rather than assuming that similarities and differences between
networks are driven by individual edges, we take a node-based approach, which
in many cases provides a more intuitive interpretation of the network
differences. We consider estimation under two distinct assumptions: (1)
differences between the K networks are due to individual nodes that are
perturbed across conditions, or (2) similarities among the K networks are due
to the presence of common hub nodes that are shared across all K networks.
Using a row-column overlap norm penalty function, we formulate two convex
optimization problems that correspond to these two assumptions. We solve these
problems using an alternating direction method of multipliers algorithm, and we
derive a set of necessary and sufficient conditions that allows us to decompose
the problem into independent subproblems so that our algorithm can be scaled to
high-dimensional settings. Our proposal is illustrated on synthetic data, a
webpage data set, and a brain cancer gene expression data set.


title: Can Large Extra Dimensions Solve the Proton Radius Puzzle?

abstract:
  The proton charge radius extracted from the recent muonic hydrogen
spectroscopy [Antognini et al. 2013; Pohl et al. 2010] differs from the CODATA
2010 recommended value [Mohr et al. 2012] by more than 4% or $4.4 \sigma$. This
discrepancy, dubbed as the "Proton Radius Puzzle", is a big challenge to the
Standard Model of particle physics, and has triggered a number of works on the
quantum electrodynamic calculations recently. The proton radius puzzle may
indicate the presence of an extra correction which enlarges the 2S-2P energy
gap in muonic hydrogen. Here we explore the possibility of large extra
dimensions which could modify the Newtonian gravity at small scales and lower
the 2S state energy while leaving the 2P state nearly unchanged. We find that
such effect could be produced by four or more large extra dimensions which are
allowed by the current constraints from low energy physics.


title:
Simplified results on the regularity of electric resistance on a
  distance-regular graph

abstract:
  Simplifications of a result from a prior paper concerning the electric
resistance between points in a distance-regular graph are given. In particular,
we prove that the maximal resistance between points is bounded by twice the
resistance between neighbors. We also show that if the constant is weakened,
then a very simple proof can be given.


title:
Estimating Confusions in the ASR Channel for Improved Topic-based
  Language Model Adaptation

abstract:
  Human language is a combination of elemental languages/domains/styles that
change across and sometimes within discourses. Language models, which play a
crucial role in speech recognizers and machine translation systems, are
particularly sensitive to such changes, unless some form of adaptation takes
place. One approach to speech language model adaptation is self-training, in
which a language model's parameters are tuned based on automatically
transcribed audio. However, transcription errors can misguide self-training,
particularly in challenging settings such as conversational speech. In this
work, we propose a model that considers the confusions (errors) of the ASR
channel. By modeling the likely confusions in the ASR output instead of using
just the 1-best, we improve self-training efficacy by obtaining a more reliable
reference transcription estimate. We demonstrate improved topic-based language
modeling adaptation results over both 1-best and lattice self-training using
our ASR channel confusion estimates on telephone conversations.


title:
Stable solutions and finite Morse index solutions of nonlinear elliptic
  equations with Hardy potential

abstract:
  We are concerned with Liouville-type results of stable solutions and finite
Morse index solutions for the following nonlinear elliptic equation with Hardy
potential: \begin{displaymath} \Delta u+\dfrac{\mu}{|x|^2}u+|x|^l |u|^{p-1}u=0
\qquad \textrm{in}\ \ \Omega, \end{displaymath} where $\Omega=\RN$,
$\RN\setminus\{0\}$ for $N\geq3$, $p>1$, $l>-2$ and $\mu<(N-2)^2/4$. Our
results depend crucially on a new critical exponent $p=p_c(l,\mu)$ and the
parameter $\mu$ in Hardy term. We prove that there exist no nontrivial stable
solution and finite Morse index solution for $1<p<p_c(l,\mu)$. We also observe
a range of the exponent $p$ larger than $p_c(l,\mu)$ satisfying that our
equation admits a positive radial stable solution.


title:
Division theorems for the rational cohomology of discriminant
  complements and applications to automorphism groups in finite characteristic

abstract:
  In this note we extend some of the results of a previous paper
\url{arXiv:math/0511593} to algebraically closed fields of finite
characteristic. In particular, we show that there is an explicit expression in
$n$ and $d$ which is divisible by the prime to $p$ part of the order of the the
automorphism group of a smooth degree $d$ hypersurface $\subset \mathbb{P}^n_k$
for $k$ an algebraically closed field of characteristic $p$.


title: Notes on hyperelliptic fibrations of genus 3, II

abstract:
  This is the part II of the series under the same title. In part I, using the
approach developed by Catanese--Pignatelli arXiv:math/0503294, we gave a
structure theorem for hyperelliptic genus 3 fibrations all of whose fibers are
2-connected (arXiv:1209.6278 [math.AG]). In this part II, we shall give a
structure theorem for smooth deformation families of these to non-hyperelliptic
genus 3 fibrations. As an application, we shall give a set of sufficient
conditions for our genus 3 hyperelliptic fibration above to allow deformation
to non-hyperelliptic fibrations, and use this to study certain minimal regular
surfaces with first Chern number 8 and geometric genus 4: we shall find in the
moduli space two strata M_0^{sharp} and M_0^{flat}$ (each of dimensions 32 and
30, respectively), and show that Bauer--Pingatelli's stratum M_0
(arXiv:math/0603094) and its 26-dimensional substratum are at the boundary of
these new strata M_0^{sharp} and M_0^{flat}, respectively.


title:
Development of Density-Functional Theory for Plasmon-Assisted
  Superconducting State: Application to Lithium Under High Pressures

abstract:
  We extend the density-functional theory for superconductors (SCDFT) to take
account of the dynamical structure of the screened Coulomb interaction. We
construct an exchange-correlation kernel in the SCDFT gap equation on the basis
of the random-phase approximation, where electronic collective excitations such
as plasmons are properly treated. Through an application to fcc lithium under
high pressures, we demonstrate that our new kernel gives higher transition
temperatures (Tc) when the plasmon and phonon cooperatively mediate pairing and
it improves the agreement between the calculated and experimentally observed
Tc. The present formalism opens the door to non-empirical studies on
unconventional electron mechanisms of superconductivity based on density
functional theory.


title: Statistical Model Building, Machine Learning, and the Ah-Ha Moment

abstract:
  The Committee of Presidents of Statistical Societies (COPSS) will celebrate
its 50th Anniversary in 2013. As part of its celebration, COPSS intends to
publish a book with contributions from the past recipients of its four awards,
namely the Fisher Lecture Award, the President's Award, the Elizabeth Scott
Award, and the FN David Award. The theme of the book is Past, Present and
Future of Statistical Science. As a winner of the Elizabeth Scott Award, I have
been invited to contribute. We were given several topics to choose from and I
have chosen to focus on "Statistical Career: Your reflection on your own
career, lessons and experience you have learned, and advice you would like to
provide to young statisticians if sought." This article is my contribution.


title:
Radial Speed Evolution of Interplanetary Coronal Mass Ejections During
  Solar Cycle 23

abstract:
  We report radial speed evolution of interplanetary coronal mass ejections
(ICMEs) detected by the SOHO/LASCO coronagraph, interplanetary scintillation
(IPS) at 327 MHz, and in-situ observations. In this study, we analyze solar
wind disturbance factor (g-value) data derived from IPS observations during
1997-2009 covering nearly the whole period of Solar Cycle 23. By comparing
observations from the SOHO/LASCO, IPS, and in situ, we then identify 39 ICMEs
that could be analyzed carefully. Here, we define two speeds V_SOHO and V_bg,
which are initial speed of ICME and the speed of the background solar wind,
respectively. Examinations of these speeds yield the following results; i) Fast
ICMEs (with V_SOHO - V_bg > 500 km/s) rapidly decelerate, moderate ICMEs (with
0 km/s < V_SOHO - V_bg < 500 km/s) show either gradually decelerating or
uniform motion, and slow ICMEs (with V_SOHO - V_bg < 0 km/s) accelerate. The
radial speeds converge on the speed of background solar wind during their
outward propagation. We subsequently find; ii) both the acceleration and
deceleration are nearly complete by 0.79 (+/- 0.04) AU, and those are ended
when the ICME speed reaches a given speed. We find the value of that to be 480
(+/- 21) km/s. iii) For the fast and moderate ICMEs, a linear equation with a
constant coefficient is more appropriate than a quadratic equation to describe
their kinematics, because the chi-square for the linear equation satisfies the
statistical significance level of 0.05, while the quadratic one is not. These
results support the hypothesis that the radial motion of ICMEs is governed by a
drag force due to interaction with the background solar wind. These findings
also suggest that ICMEs propagating faster than background solar wind are
controlled mainly by the hydrodynamic Stokes drag.


title: Homology representations of unitary reflection groups

abstract:
  This paper continues the study of the poset of eigenspaces of elements of a
unitary reflection group (for a fixed eigenvalue), which was commenced in [6]
and [5]. The emphasis in this paper is on the representation theory of unitary
reflection groups. The main tool is the theory of poset extensions due to Segev
and Webb ([16]). The new results place the well-known representations of
unitary reflection groups on the top homology of the lattice of intersections
of hyperplanes into a natural family, parameterised by eigenvalue.


title: Choosability of the square of a planar graph with maximum degree four

abstract:
  We study squares of planar graphs with the aim to determine their list
chromatic number. We present new upper bounds for the square of a planar graph
with maximum degree $\Delta \leq 4$. In particular $G^2$ is 5-, 6-, 7-, 8-,
12-, 14-choosable if the girth of $G$ is at least 16, 11, 9, 7, 5, 3
respectively. In fact we prove more general results, in terms of maximum
average degree, that imply the results above.


title: Transmit Antenna Selection with Alamouti Scheme in MIMO Wiretap Channels

abstract:
  This paper proposes a new transmit antenna selection (TAS) scheme which
provides enhanced physical layer security in multiple-input multiple-output
(MIMO) wiretap channels. The practical passive eavesdropping scenario we
consider is where channel state information (CSI) from the eavesdropper is not
available at the transmitter. Our new scheme is carried out in two steps.
First, the transmitter selects the first two strongest antennas based on the
feedback from the receiver, which maximizes the instantaneous signal-to-noise
ratio (SNR) of the transmitter-receiver channel. Second, the Alamouti scheme is
employed at the selected antennas in order to perform data transmission. At the
receiver and the eavesdropper, maximal-ratio combining is applied in order to
exploit the multiple antennas.We derive a new closed-form expression for the
secrecy outage probability in nonidentical Rayleigh fading, and using this
result, we then present the probability of non-zero secrecy capacity in closed
form and the {\epsilon}-outage secrecy capacity in numerical form. We
demonstrate that our proposed TAS-Alamouti scheme offers lower secrecy outage
probability than a single TAS scheme when the SNR of the transmitter-receiver
channel is above a specific value.


title: Cylindrical wormholes in DGP gravity

abstract:
  We construct traversable thin-shell wormholes in the Dvali-Gabadadze-Porrati
theory with cylindrical symmetry applying the cut and paste procedure to a flat
black string solution of the five-dimensional vacuum Einstein field equations.
In contrast to general relativity case, where thin-shell wormholes violate both
weak and null energy conditions, we show that static wormholes are supported by
normal matter while vacuum wormholes do not exist.


title: Mickelsson's twisted K-theory invariant and its generalizations

abstract:
  Mickelsson's invariant is an invariant of certain odd twisted K-classes of
compact oriented three dimensional manifolds. We reformulate the invariant as a
natural homomorphism taking values in a quotient of the third cohomology, and
provide a generalization taking values in a quotient of the fifth cohomology.
These homomorphisms are related to the Atiyah-Hirzebruch spectral sequence. We
also construct some characteristic classes for odd twisted K-theory in a
similar vein.


title:
Regularity over homomorphisms and a Frobenius characterization of Koszul
  algebras

abstract:
  Let $R$ be a standard graded algebra over an $F$-finite field of
characteristic $p > 0$. Let $\phi:R\to R$ be the Frobenius endomorphism. For
each finitely generated graded $R$-module $M$, let ${}^{\phi}\!M$ be the
abelian group $M$ with the $R$-module structure induced by the Frobenius
endomorphism. The $R$-module ${}^{\phi}\!M$ has a natural grading given by
$\text{deg} x=j$ if $x\in M_{jp+i}$ for some $0\le i \le p-1$. In this paper,
we prove that $R$ is Koszul if and only if there exists a non-zero finitely
generated graded $R$-module $M$ such that $\text{reg}_R\,{}^{\phi}\!M <\infty$.
This result supplies another instance for the ability of the Frobenius in
detecting homological properties, as exemplified by Kunz's famous regularity
criterion. The main technical tool is the notion of Castelnuovo-Mumford
regularity over certain homomorphisms between $\mathbb{N}$-graded algebras. The
latter notion is a common generalization of the relative and absolute
Castelnuovo-Mumford regularity of modules.


title: Random Walks and Subfractional Brownian Motion

abstract:
  In this article, we show a result of approximation in law to subfractional
Brownian motion, with $H>\frac{1}{2}$, in the Skorohod topology. The
construction of these approximations is based on a sequence of I.I.D random
variables


title: Fibonacci Numbers and Identities

abstract:
  By investigating a recurrence relation about functions, we first give
alternative proofs of various identities on Fibonacci numbers and Lucas
numbers, and then, make certain well known identities visible via certain
trivalent graph associated to the recurrence relation.


title: Inventory Control for Spectrally Positive Levy Demand Processes

abstract:
  A new approach to solve the continuous-time stochastic inventory problem
using the fluctuation theory of Levy processes is developed. This approach
involves the recent developments of the scale function that is capable of
expressing many fluctuation identities of spectrally one-sided Levy processes.
For the case with a fixed cost and a general spectrally positive Levy demand
process, we show the optimality of an (s,S)-policy. The optimal policy and the
value function are concisely expressed via the scale function. Numerical
examples under a Levy process in the beta-family with jumps of infinite
activity are provided to confirm the analytical results. Furthermore, the case
with no fixed ordering costs is studied.


title:
Kernelet: High-Throughput GPU Kernel Executions with Dynamic Slicing and
  Scheduling

abstract:
  Graphics processors, or GPUs, have recently been widely used as accelerators
in the shared environments such as clusters and clouds. In such shared
environments, many kernels are submitted to GPUs from different users, and
throughput is an important metric for performance and total ownership cost.
Despite the recently improved runtime support for concurrent GPU kernel
executions, the GPU can be severely underutilized, resulting in suboptimal
throughput. In this paper, we propose Kernelet, a runtime system with dynamic
slicing and scheduling techniques to improve the throughput of concurrent
kernel executions on the GPU. With slicing, Kernelet divides a GPU kernel into
multiple sub-kernels (namely slices). Each slice has tunable occupancy to allow
co-scheduling with other slices and to fully utilize the GPU resources. We
develop a novel and effective Markov chain based performance model to guide the
scheduling decision. Our experimental results demonstrate up to 31.1% and 23.4%
performance improvement on NVIDIA Tesla C2050 and GTX680 GPUs, respectively.


title:
Direct calculation of the solid-liquid Gibbs free energy difference in a
  single equilibrium simulation

abstract:
  Computing phase diagrams of model systems is an essential part of
computational condensed matter physics. In this paper we discuss in detail the
interface pinning (IP) method for calculation of the Gibbs free energy
difference between a solid and a liquid. This is done in a single equilibrium
simulation by applying a harmonic field that biases the system towards
two-phase configurations. The Gibbs free energy difference between the phases
is determined from the average force that the applied field exerts on the
system. As a test system we study the Lennard-Jones model. It is shown that the
coexistence line can be computed efficiently to a high precision when the IP
method is combined with the Newton-Raphson method for finding roots.
Statistical and systematic errors are investigated. Advantages and drawbacks of
the IP method are discussed. The high pressure part of the temperature-density
coexistence region is outlined by isomorphs.


title: Charge-SQUID and Tunable Phase-slip Flux Qubit

abstract:
  A phase-slip flux qubit, exactly dual to a charge qubit, is composed of a
superconducting loop interrupted by a phase-slip junction. Here we propose a
tunable phase-slip flux qubit by replacing the phase-slip junction with a
charge-related superconducting quantum interference device (SQUID) consisting
of two phase-slip junctions connected in series with a superconducting island.
This charge-SQUID acts as an effective phase-slip junction controlled by the
applied gate voltage and can be used to tune the energy-level splitting of the
qubit. Also, we show that a large inductance inserted in the loop can reduce
the inductance energy and consequently suppress the dominating flux noise of
the phase-slip flux qubit. This enhanced phase-slip flux qubit is exactly dual
to a transmon qubit.


title: Bulk Viscous Matter-dominated Universes: Asymptotic Properties

abstract:
  By means of a combined use of the type Ia supernovae and H(z) data tests,
together with the study of the asymptotic properties in the equivalent phase
space - through the use of the dynamical systems tools - we demonstrate that
the bulk viscous matter-dominated scenario is not a good model to explain the
accepted cosmological paradigm, at least, under the parametrization of bulk
viscosity considered in this paper. The main objection against such scenarios
is the absence of conventional radiation and matter-dominated critical points
in the phase space of the model. This entails that radiation and matter
dominance are not generic solutions of the cosmological equations, so that
these stages can be implemented only by means of unique and very specific
initial conditions, i. e., of very unstable particular solutions. Such a
behavior is in marked contradiction with the accepted cosmological paradigm
which requires of an earlier stage dominated by relativistic species, followed
by a period of conventional non-relativistic matter domination, during which
the cosmic structure we see was formed. Also, we found that the bulk viscosity
is positive just until very late times in the cosmic evolution, around z < 1.
For earlier epochs it is negative, been in tension with the local second law of
thermodynamics.


title: Noncommutative geometry of groups like $\Gamma_0(N)$

abstract:
  We show that the Connes-Marcolli $GL_{2}$-system can be represented on the
Big Picture, a combinatorial gadget introduced by Conway in order to understand
various results about congruence subgroups pictorially. In this representation
the time evolution of the system is implemented by Conway's distance between
projective classes of commensurable lattices. We exploit these results in order
to associate quantum statistical mechanical systems to congruence subgroups in
a way appropriate for the study of monstrous moonshine.


title: Practical approach to the sign problem at finite theta-vacuum angle

abstract:
  We investigate a way of circumventing the sign problem in lattice QCD
simulations with a theta-vacuum term, using the PNJL model. We consider the
reweighting method for the QCD Lagrangian after the U_A(1) transformation. In
the Lagrangian, the P-odd mass term as a cause of the sign problem is
minimized. In order to find out a good reference system in the reweighting
method, we estimate the average reweighting factor by using the two-flavor PNJL
model and eventually find a good reference system.


title:
The Correlation between Dispersion Measure and X-ray Column Density from
  Radio Pulsars

abstract:
  Pulsars are remarkable objects that emit across the entire electromagnetic
spectrum, providing a powerful probe of the interstellar medium. In this study,
we investigate the relation between dispersion measure (DM) and X-ray
absorption column density NH using 68 radio pulsars detected at X-ray energies
with the Chandra X-ray Observatory or XMM-Newton. We find a best-fit empirical
linear relation of NH (10^20 cm^-2)= 0.30+0.13-0.09 DM (pc cm^-3), which
corresponds to an average ionization of 10+4-3%, confirming the ratio of one
free electron per ten neutral hydrogen atoms commonly assumed in the
literature. We also compare different NH estimates and note that some NH values
obtained from X-ray observations are higher than the total Galactic HI column
density along the same line of sight, while the optical extinction generally
gives the best NH predictions.


title: The generalized 3-connectivity of random graphs

abstract:
  The generalized connectivity of a graph $G$ was introduced by Chartrand et
al. Let $S$ be a nonempty set of vertices of $G$, and $\kappa(S)$ be defined as
the largest number of internally disjoint trees $T_1, T_2, \cdots, T_k$
connecting $S$ in $G$. Then for an integer $r$ with $2 \leq r \leq n$, the {\it
generalized $r$-connectivity} $\kappa_r(G)$ of $G$ is the minimum $\kappa(S)$
where $S$ runs over all the $r$-subsets of the vertex set of $G$. Obviously,
$\kappa_2(G)=\kappa(G)$, is the vertex connectivity of $G$, and hence the
generalized connectivity is a natural generalization of the vertex
connectivity. Similarly, let $\lambda(S)$ denote the largest number $k$ of
pairwise edge-disjoint trees $T_1, T_2, \ldots, T_k$ connecting $S$ in $G$.
Then the {\it generalized $r$-edge-connectivity} $\lambda_r(G)$ of $G$ is
defined as the minimum $\lambda(S)$ where $S$ runs over all the $r$-subsets of
the vertex set of $G$. Obviously, $\lambda_2(G) = \lambda(G)$.
  In this paper, we study the generalized 3-connectivity of random graphs and
prove that for every fixed integer $k\geq 1$, $$p=\frac{{\log n+(k+1)\log \log
n -\log \log \log n}}{n}$$ is a sharp threshold function for the property
$\kappa_3(G(n, p)) \geq k$, which could be seen as a counterpart of
Bollob\'{a}s and Thomason's result for vertex connectivity. Moreover, we obtain
that $\delta (G(n,p)) - 1 = \lambda (G(n,p)) - 1 = \kappa (G(n,p)) - 1 \le
{\kappa_3}(G(n,p)) \le {\lambda_3}(G(n,p)) \le \kappa (G(n,p)) = \lambda
(G(n,p)) = \delta (G(n,p))$ almost surely holds, which could be seen as a
counterpart of Ivchenko's result.


title:
Respondent privacy and estimation efficiency in randomized response
  surveys for discrete-valued sensitive variables

abstract:
  In some socio-economic surveys, data are collected on sensitive or
stigmatizing issues such as tax evasion, criminal conviction, drug use, etc. In
such surveys, direct questioning of respondents is not of much use and the
randomized response technique is used instead. A few researchers have studied
the issue of privacy protection or respondent jeopardy for surveys on
dichotomous populations, where the objective is to estimate the proportion of
persons bearing the sensitive trait. However, not much is yet known about
respondent protection when the variable under study takes discrete numerical
values and the objective of the survey is to estimate the population mean of
this variable. In this article we study this issue. We first propose a
randomization device for this situation and give the corresponding estimation
procedure. We next propose a measure of privacy and show that given a certain
stipulated level of this privacy measure, we can determine the parameter of the
randomization device so as to maximize the efficiency of estimation, while
guaranteeing the desired level of privacy protection. In particular, our study
also covers the case of polychotomous populations and we can estimate the
proportions of individuals belonging to the different classes. Consequently,
results for dichotomous populations follow as corollaries.


title:
Emergent Odd-Frequency Superconducting Order Parameter near Boundaries
  in Unconventional Superconductors

abstract:
  It was previously suggested that an odd-frequency pair amplitude exists in
the vicinity of boundaries in unconventional superconductors. We develop this
idea and quest for a novel superconducting order parameter with an
odd-frequency dependence. For this purpose, we focus on p-wave superconductors
and extend the quasi-classical theory to include the odd-frequency dependence
in the order parameter. Both of the frequency and spacial dependences of the
order parameter are determined self-consistently. Under a finite
electron-phonon interaction, it is found that an odd-frequency order parameter
is stabilized near the boundary and coexists with the even-frequency one. By
analyzing the induced odd-frequency pair amplitude in terms of the
superconducting quasi-particle wavefunction, it is found that the mid-gap bound
state generates the emergent odd-frequency order parameter.


title:
The Acceleration of Thermal Protons at Parallel Collisionless Shocks:
  Three-dimensional Hybrid Simulations

abstract:
  We present three-dimensional hybrid simulations of collisionless shocks that
propagate parallel to the background magnetic field to study the acceleration
of protons that forms a high-energy tail on the distribution. We focus on the
initial acceleration of thermal protons and compare it with results from
one-dimensional simulations. We find that for both one- and three-dimensional
simulations, particles that end up in the high-energy tail of the distribution
later in the simulation gained their initial energy right at the shock. This
confirms previous results but is the first to demonstrate this using fully
three-dimensional fields. The result is not consistent with the "thermal
leakage" model. We also show that the gyrocenters of protons in the
three-dimensional simulation can drift away from the magnetic field lines on
which they started due to the removal of ignorable coordinates that exist in
one- and two-dimensional simulations. Our study clarifies the injection problem
for diffusive shock acceleration.

categories: astro-ph.HE astro-ph.SR physics.plasm-ph physics.space-ph


title: Discovery of Convoys in Network Proximity Log

abstract:
  This paper describes an algorithm for discovery of convoys in database with
proximity log. Traditionally, discovery of convoys covers trajectories
databases. This paper presents a model for context-aware browsing application
based on the network proximity. Our model uses mobile phone as proximity sensor
and proximity data replaces location information. As per our concept, any
existing or even especially created wireless network node could be used as
presence sensor that can discover access to some dynamic or user-generated
content. Content revelation in this model depends on rules based on the
proximity. Discovery of convoys in historical user's logs provides a new class
of rules for delivering local content to mobile subscribers.


title:
Material dependence of Casimir interaction between a sphere and a plate:
  First analytic correction beyond proximity force approximation

abstract:
  We derive analytically the asymptotic behavior of the Casimir interaction
between a sphere and a plate when the distance between them, $d$, is much
smaller than the radius of the sphere, $R$. The leading order and
next-to-leading order terms are derived from the exact formula for the Casimir
interaction energy. They are found to depend nontrivially on the dielectric
functions of the objects. As expected, the leading order term coincides with
that derived using the proximity force approximation. The result on the
next-to-leading order term complements that found by Bimonte, Emig and Kardar
[Appl. Phys. Lett. \textbf{100}, 074110 (2012)] using derivative expansion.
Numerical results are presented when the dielectric functions are given by the
plasma model or the Drude model, with the plasma frequency (for plasma and
Drude models) and relaxation frequency (for Drude model) given respectively by
9eV and 0.035eV, the conventional values used for gold metal. It is found that
if plasma model is used instead of Drude model, the error in the sum of the
first two leading terms is at most 2%, while the error in $\theta_1$, the ratio
of the next-to-leading order term divided by $d/R$ to the leading order term,
can go up to 4.5%.


title:
Model Based Framework for Estimating Mutation Rate of Hepatitis C Virus
  in Egypt

abstract:
  Hepatitis C virus (HCV) is a widely spread disease all over the world. HCV
has very high mutation rate that makes it resistant to antibodies. Modeling HCV
to identify the virus mutation process is essential to its detection and
predicting its evolution. This paper presents a model based framework for
estimating mutation rate of HCV in two steps. Firstly profile hidden Markov
model (PHMM) architecture was builder to select the sequences which represents
sequence per year. Secondly mutation rate was calculated by using pair-wise
distance method between sequences. A pilot study is conducted on NS5B zone of
HCV dataset of genotype 4 subtype a (HCV4a) in Egypt.


title: Local Inversions in Ultrasound Modulated Optical Tomography

abstract:
  Ultrasound modulated optical tomography, also called acousto-optics
tomography, is a hybrid imaging modality that aims to combine the high contrast
of optical waves with the high resolution of ultrasound. We follow the model of
the influence of ultrasound modulation on the light intensity measurements
developed in [Bal Schotland PRL 2010]. We present sufficient conditions
ensuring that the absorption and diffusion coefficients modeling light
propagation can locally be uniquely and stably reconstructed from the
corresponding available information. We present an iterative procedure to solve
such a problem based on the analysis of linear elliptic systems of redundant
partial differential equations.


title:
Surface growth effects on reactive capillary-driven flow: Lattice
  Boltzmann investigation

abstract:
  The Washburn law has always played a critical role for ceramics. In the
microscale, surface forces take over volume forces and the phenomenon of
spontaneous infiltration in narrow interstices becomes of particular relevance.
The Lattice Boltzmann method is applied in order to ascertain the role of
surface reaction and subsequent deformation of a single capillary in 2D for the
linear Washburn behavior. The proposed investigation is motivated by the
problem of reactive infiltration of molten silicon into carbon preforms. This
is a complex phenomenon arising from the interplay between fluid flow, the
transition to wetting, surface growth and heat transfer. Furthermore, it is
characterized by slow infiltration velocities in narrow interstices resulting
in small Reynolds numbers that are difficult to reproduce with a single
capillary. In our simulations, several geometric characteristics for the
capillaries are considered, as well as different infiltration and reaction
conditions. The main result of our work is that the phenomenon of pore closure
can be regarded as independent of the infiltration velocity, and in turn a
number of other parameters. The instrumental conclusion drawn from our
simulations is that short pores with wide openings and a round-shaped
morphology near the throats represent the optimal configuration for the
underlying structure of the porous preform in order to achieve faster
infiltration. The role of the approximations is discussed in detail and the
robustness of our findings is assessed.


title:
On the optimality of the aggregate with exponential weights for low
  temperatures

abstract:
  Given a finite class of functions F, the problem of aggregation is to
construct a procedure with a risk as close as possible to the risk of the best
element in the class. A classical procedure (PAC-Bayesian statistical learning
theory (2004) Paris 6, Statistical Learning Theory and Stochastic Optimization
(2001) Springer, Ann. Statist. 28 (2000) 75-87) is the aggregate with
exponential weights (AEW), defined by \[\tilde{f}^{\mathrm{AEW}}=\sum_{f\in
F}\hat{\theta}(f)f,\qquad where
\hat{\theta}(f)=\frac{\exp(-({n}/{T})R_n(f))}{\sum_{g\in
F}\exp(-({n}/{T})R_n(g))},\] where $T>0$ is called the temperature parameter
and $R_n(\cdot)$ is an empirical risk. In this article, we study the optimality
of the AEW in the regression model with random design and in the
low-temperature regime. We prove three properties of AEW. First, we show that
AEW is a suboptimal aggregation procedure in expectation with respect to the
quadratic risk when $T\leq c_1$, where $c_1$ is an absolute positive constant
(the low-temperature regime), and that it is suboptimal in probability even for
high temperatures. Second, we show that as the cardinality of the dictionary
grows, the behavior of AEW might deteriorate, namely, that in the
low-temperature regime it might concentrate with high probability around
elements in the dictionary with risk greater than the risk of the best function
in the dictionary by at least an order of $1/\sqrt{n}$. Third, we prove that if
a geometric condition on the dictionary (the so-called "Bernstein condition) is
assumed, then AEW is indeed optimal both in high probability and in expectation
in the low-temperature regime. Moreover, under that assumption, the complexity
term is essentially the logarithm of the cardinality of the set of "almost
minimizers" rather than the logarithm of the cardinality of the entire
dictionary. This result holds for small values of the temperature parameter,
thus complementing an analogous result for high temperatures.