title: End-to-end Learning of Deep Visual Representations for Image Retrieval

abstract:
  While deep learning has become a key ingredient in the top performing methods
for many computer vision tasks, it has failed so far to bring similar
improvements to instance-level image retrieval. In this article, we argue that
reasons for the underwhelming results of deep methods on image retrieval are
threefold: i) noisy training data, ii) inappropriate deep architecture, and
iii) suboptimal training procedure. We address all three issues.
  First, we leverage a large-scale but noisy landmark dataset and develop an
automatic cleaning method that produces a suitable training set for deep
retrieval. Second, we build on the recent R-MAC descriptor, show that it can be
interpreted as a deep and differentiable architecture, and present improvements
to enhance it. Last, we train this network with a siamese architecture that
combines three streams with a triplet loss. At the end of the training process,
the proposed architecture produces a global image representation in a single
forward pass that is well suited for image retrieval. Extensive experiments
show that our approach significantly outperforms previous retrieval approaches,
including state-of-the-art methods based on costly local descriptor indexing
and spatial verification. On Oxford 5k, Paris 6k and Holidays, we respectively
report 94.7, 96.6, and 94.8 mean average precision. Our representations can
also be heavily compressed using product quantization with little loss in
accuracy. For additional material, please see
www.xrce.xerox.com/Deep-Image-Retrieval.


title:
Distinguishability notion based on Wootters statistical distance:
  application to discrete maps

abstract:
  We study the distinguishability notion given by Wootters for states
represented by probability density functions. This presents the particularity
that it can also be used for defining a distance in chaotic unidimensional
maps. Based on that definition, we provide a metric $\overline{d}$ for an
arbitrary discrete map. Moreover, from this we associate a metric space to each
invariant density of a given map, which results to be the set of all
distinguished points when the number of iterations of the map tends to
infinity. Also, we give a characterization of the wandering set of a map in
terms of the given metric which allows to identify the dissipative regions in
the phase space. We illustrate the results in the case of the logistic and the
circle maps numerically and theoretically, and we obtain the metric and the
wandering set for some characteristic values of their parameters.


title:
The Effect of Noise on the Propagating Speed of Pre-mixed Laminar Flame
  Fronts

abstract:
  We study the effect of thermal noise on the propagation speed of a planar
flame. We show that this out of equilibrium greatly amplifies the effect of
thermal noise to yield macroscopic reductions in the flame speed over what is
predicted by the noise-free model. Computations show that noise slows the flame
significantly. The flame is modeled using Navier Stokes equations with
appropriate diffusive transport terms and chemical kinetic mechanism of
hydrogen/oxygen. Thermal noise is modeled within the continuum framework using
a system of stochastic partial differential equations, with transport noise
from fluctuating hydrodynamics and reaction noise from a poisson model. We use
a full chemical kinetics model in order to get quantitatively meaningful
results. We compute steady and dynamic flames using an operator split finite
volume scheme. New characteristic boundary conditions avoid non-physical
boundary layers at computational boundaries. New limiters prevent stochastic
terms from introducing non-physical negative concentrations. This represents
the first computation of a model with thermal noise is a system with this
degree of physical detail.


title: Theory Overview

abstract:
  We set the scene for theoretical issues in charm physics that were discussed
at CHARM 2016 in Bologna. In particular we emphasize the importance of
improving our understanding of standard model contributions to numerous charm
observables and we discuss also possible tests of our theory tools, like the
Heavy Quark Expansion via the lifetime ratios of $D$-mesons


title: IB2d: a Python and MATLAB implementation of the immersed boundary method

abstract:
  The development of fluid-structure interaction (FSI) software involves
trade-offs between ease of use, generality, performance, and cost. Typically
there are large learning curves when using low-level software to model the
interaction of an elastic structure immersed in a uniform density fluid. Many
existing codes are not publicly available, and the commercial software that
exists usually requires expensive licenses and may not be as robust or allow
the necessary flexibility that in house codes can provide. We present an open
source immersed boundary software package, IB2d, with full implementations in
both MATLAB and Python, that is capable of running a vast range of biomechanics
models and is accessible to scientists who have experience in high-level
programming environments. IB2d contains multiple options for constructing
material properties of the fiber structure, as well as the advection-diffusion
of a chemical gradient, muscle mechanics models, and artificial forcing to
drive boundaries with a preferred motion.


title: Real zeros of the Hurwitz zeta function

abstract:
  It is well known that real zeros of the Riemann zeta function are negative
even integers. As for real zeros of the Hurwitz zeta function, T. Nakamura
recently gave an existence condition in the intervals (0,1) and (-1,0). We
generalize this result for all negative real numbers.


title: An idelic view of ideals

abstract:
  Ideles and adeles can be viewed as a generalization of Minkowski theory, in
which embedding of a number field to the Cartesian product of its completions
at the archimedean valuation is generalized to an embedding of the Cartesian
product of all its completions with some restriction. This paper introduces the
basic notions of point-set topology and builds the real numbers from the
rational numbers. Then we review concepts from local fields that will lead to
the product formula and the approximation theorem. We, then, construct adeles
and ideles. The ideles modulo $k^*$ maps surjectively to the ideal class group,
and the compactness of $C_S^0$ will give rise to an alternative proof to the
Dirichlet's S-unit theorem and the finiteness of ideal class group. The paper
assumes that the reader is familiar with Dedekind domain, principal ideal
domain, unique factorization of Dedekind domain, and field norm and traces. The
first few parts of Chapter 1 in Neukirch's Algebraic Number Theory will be
sufficient for the paper.


title: What produces the far-infrared/submm emission in the most luminous QSOs?

abstract:
  The AGN. I examine the average spectral energy distributions (SEDs) of two
samples of the most powerful, unobscured QSOs at 2<z<3.5, with rest frame
optical luminosities in the 46.2<log vLv(5100Ang)<47.4 range, corresponding to
the tail of the 2<z<4 QSO optical luminosity function. I find that the AGN
could potentially account for the entire broad-band emission from the UV to the
submm, on the basis that the SEDs of these sources are similar to the intrinsic
AGN SEDs derived for lower power, lower redshift QSOs. Although this does not
preclude substantial star-formation in their host galaxies, I find that the AGN
dominates the total infrared luminosity, removing the necessity for a
star-forming component in the far-IR/submm. I argue that the origin of the
far-IR/submm emission in such powerful QSOs includes a small contribution from
the AGN torus, but is predominantly linked to dust at kpc-scales heated by the
AGN. The latter component accounts for at least 5-10 per cent of the bolometric
AGN luminosity and has an implied dust mass of the order of 10^8 solar masses.


title: Revocable Hierarchical Identity-Based Encryption from Multilinear Maps

abstract:
  In identity-based encryption (IBE) systems, an efficient key delegation
method to manage a large number of users and an efficient key revocation method
to handle the dynamic credentials of users are needed. Revocable hierarchical
IBE (RHIBE) can provide these two methods by organizing the identities of users
as a hierarchy and broadcasting an update key for non-revoked users per each
time period. To provide the key revocation functionality, previous RHIBE
schemes use a tree-based revocation scheme. However, this approach has an
inherent limitation such that the number of update key elements depends on the
number of revoked users.
  In this paper, we propose two new RHIBE schemes in multilinear maps that use
the public-key broadcast encryption scheme instead of using the tree-based
revocation scheme to overcome the mentioned limitation. In our first RHIBE
scheme, the number of private key elements and update key elements is reduced
to $O(\ell)$ and $O(\ell)$ respectively where $\ell$ is the depth of a
hierarchical identity. In our second RHIBE scheme, we can further reduce the
number of private key elements from $O(\ell)$ to $O(1)$.


title: Statistical Inference Based on a New Weighted Likelihood Approach

abstract:
  We discuss a new weighted likelihood method for parametric estimation. The
method is motivated by the need for generating a simple estimation strategy
which provides a robust solution that is simultaneously fully efficient when
the model is correctly specified. This is achieved by appropriately weighting
the score function at each observation in the maximum likelihood score
equation. The weight function determines the compatibility of each observation
with the model in relation to the remaining observations and applies a
downweighting only if it is necessary, rather than automatically downweighting
a proportion of the observations all the time. This allows the estimators to
retain full asymptotic efficiency at the model. We establish all the
theoretical properties of the proposed estimators and substantiate the theory
developed through simulation and real data examples. Our approach provides an
alternative to the weighted likelihood method of Markatou et al. (1997, 1998).


title: Narrow-linewidth cooling of $^{6}$Li atoms using the 2S-3P transition

abstract:
  We report on a narrow-linewidth cooling of $^{6}$Li atoms using the
$2S_{1/2}\to 3P_{3/2}$ transition in the ultraviolet (UV) wavelength regime. By
combining the traditional red magneto-optical trap (MOT) at 671 nm and the UV
MOT at 323 nm, we obtain a cold sample of $1.3\times10^9$ atoms with a
temperature of 58 $\mu$K. Furthermore, we demonstrate a high efficiency
magnetic transport for $^{6}$Li atoms with the help of the UV MOT. Finally, we
obtain $8.1\times10^8$ atoms with a temperature of 296 $\mu$K at a magnetic
gradient of 198 G/cm in the science chamber with a good vacuum environment and
large optical access.


title:
Comment on "Fermion production in a magnetic field in a de Sitter
  universe"

abstract:
  We point out that the transition probabilities used in a recent perturbative
calculation of pair creation in an external magnetic field in the expanding de
Sitter space with the $in$ and $out$ fermion states defined by the Bunch-Davies
modes [C. Crucean et al., Phys. Rev. D 73 044019 (20016)] are gauge dependent
quantities. We examine the gauge variations of these amplitudes assuming a
decoupling of the interaction at infinite times, which allows to conclude that
the source of the problem lies in the nonoscillatory behavior of the fermion
current in the infinite future.


title:
Uniform rationality of the Poincar\'e series of definable, analytic
  equivalence relations on local fields

abstract:
  Poincar\'e series of $p$-adic, definable equivalence relations have been
studied in various cases since Igusa's and Denef's work related to counting
solutions of polynomial equations modulo $p^n$ for prime $p$. General
semi-algebraic equivalence relations on local fields have been studied
uniformly in $p$ recently in \cite{16}. Here we generalize the rationality
result of \cite{16} to the analytic case, unifomly in $p$, building further on
the appendix of \cite{16} and on \cite{13b}, \cite{03}. In particular, the
results hold for large positive characteristic local fields. We also introduce
rational motivic constructible functions and their motivic integrals, as a tool
to prove our main results.


title:
A reconnection-driven model of the hard X-ray loop-top source from flare
  2004-Feb-26

abstract:
  A compact X-class flare on 2004-Feb-26 showed a concentrated source of hard
X-rays at the tops of the flare's loops. This was analyzed in previous work
(Longcope et al. 2010), and interpreted as plasma heated and compressed by slow
magnetosonic shocks generated during post-reconnection retraction of the flux.
That work used analytic expressions from a thin flux tube (TFT) model, which
neglected many potentially important factors such as thermal conduction and
chromospheric evaporation. Here we use a numerical solution of the TFT
equations to produce a more comprehensive and accurate model of the same flare,
including those effects previously omitted. These simulations corroborate the
prior hypothesis that slow mode shocks persist well after the retraction has
ended, thus producing a compact, loop-top source instead of an elongated jet,
as steady reconnection models predict. Thermal conduction leads to densities
higher than analytic estimates had predicted, and evaporation enhances the
density still higher, but at lower temperatures. X-ray light curves and spectra
are synthesized by convolving the results from a single TFT simulation with the
rate at which flux is reconnected, as measured through motion of flare ribbons,
for example. These agree well with light curves observed by RHESSI and GOES and
spectra from RHESSI. An image created from a superposition of TFT model runs
resembles one produced from RHESSI observations. This suggests that the HXR
loop-top source, at least the one observed in this flare, could be the result
of slow magnetosonic shocks produced in fast reconnection models like
Petschek's.


title: Local coderivatives and approximation of Hodge Laplace problems

abstract:
  The standard mixed finite element approximations of Hodge Laplace problems
associated with the de Rham complex are based on proper discrete subcomplexes.
As a consequence, the exterior derivatives, which are local operators, are
computed exactly. However, the approximations of the associated coderivatives
are nonlocal. In fact, this nonlocal property is an inherent consequence of the
mixed formulation of these methods, and can be argued to be an undesired effect
of these schemes. As a consequence, it has been argued, at least in special
settings, that more local methods may have improved properties. In the present
paper, we construct such methods by relying on a careful balance between the
choice of finite element spaces, degrees of freedom, and numerical integration
rules. Furthermore, we establish key convergence estimates based on a standard
approach of variational crimes.


title:
Gravitational Waves from Pulsars and Their Braking Indices: The Role of
  a Time Dependent Magnetic Ellipticity

abstract:
  We study the role of time dependent magnetic ellipticities ($\epsilon_{B}$)
on the calculation of the braking index of pulsars. Moreover, we study the
consequences of such a $\epsilon_{B}$ on the amplitude of gravitational waves
(GWs) generated by pulsars with measured braking indices. We show that, since
the ellipticity generated by the magnetic dipole is extremely small, the
corresponding amplitude of GWs is much smaller than the amplitude obtained via
the spindown limit.


title:
Multi-D magnetohydrodynamic modelling of pulsar wind nebulae: recent
  progress and open questions

abstract:
  In the last decade, the relativistic magnetohydrodynamic (MHD) modelling of
pulsar wind nebulae, and of the Crab nebula in particular, has been highly
successful, with many of the observed dynamical and emission properties
reproduced down to the finest detail. Here, we critically discuss the results
of some of the most recent studies: namely the investigation of the origin of
the radio emitting particles and the quest for the acceleration sites of
particles of different energies along the termination shock, by using wisps
motion as a diagnostic tool; the study of the magnetic dissipation process in
high magnetization nebulae by means of new long-term three-dimensional
simulations of the pulsar wind nebula evolution; the investigation of the
relativistic tearing instability in thinning current sheets, leading to fast
reconnection events that might be at the origin of the Crab nebula gamma-ray
flares.


title:
Analytical On-shell Calculation of Higher Order Scattering: Massive
  Particles

abstract:
  We demonstrate that the use of on-shell methods, involving calculation of the
discontinuity across the t-channel cut associated with the exchange of a pair
of massless particles, can be used to evaluate loop contributions to both the
electromagnetic and gravitational scattering of massive systems. In the
gravitational case, the use of factorization permits a straightforward and
algebraic calculation of higher order scattering results, which were obtained
previously by much more arduous Feynman diagram techniques.


title:
On the Decay of Almost Periodic Solutions of Anisotropic Degenerate
  Parabolic-Hyperbolic Equations

abstract:
  We discuss the well-posedness and decay of Besicovitch almost periodic
solutions for a class of nonlinear degenerate anisotropic hyperbolic-parabolic
equations. In our definition of weak entropy solution the initial data is only
assumed in a weak sense, and in this connection the strong trace of the
solution in the initial time hyperplane is also established.


title: On Pasch's Axiom and Desargues' Theorem in Busemann's work

abstract:
  In this note, we discuss the role played by the techniques from the
"foundations of geometry" and in particular by Desargues' Theorem in the work
of Busemann. This note is part of a forthcoming edition of Busemann's collected
papers.


title: Cost and Precision of Brownian Clocks

abstract:
  Brownian clocks are biomolecular networks that can count time. A paradigmatic
example are proteins that go through a cycle thus regulating some oscillatory
behaviour in a living system. Typically, such a cycle requires free energy
often provided by ATP hydrolysis. We investigate the relation between the
precision of such a clock and its thermodynamic costs. For clocks driven by a
constant thermodynamic force, a given precision requires a minimal cost that
diverges as the uncertainty of the clock vanishes. In marked contrast, we show
that a clock driven by a periodic variation of an external protocol can achieve
arbitrary precision at arbitrarily low cost. This result constitutes a
fundamental difference between processes driven by a fixed thermodynamic force
and those driven periodically. As a main technical tool, we map a periodically
driven system with a deterministic protocol to one subject to an external
protocol that changes in stochastic time intervals, which simplifies
calculations significantly. In the non-equilibrium steady state of the
resulting bipartite Markov process, the uncertainty of the clock can be deduced
from the calculable dispersion of a corresponding current.


title:
Optimal Regularity for the Thin Obstacle Problem with $C^{0,\alpha}$
  Coefficients

abstract:
  In this article we study solutions to the (interior) thin obstacle problem
under low regularity assumptions on the coefficients, the obstacle and the
underlying manifold. Combining the linearization method of Andersson
\cite{An16} and the epiperimetric inequality from \cite{FS16}, \cite{GPSVG15},
we prove the optimal $C^{1,\min\{\alpha,1/2\}}$ regularity of solutions in the
presence of $C^{0,\alpha}$ coefficients $a^{ij}$ and $C^{1,\alpha}$ obstacles
$\phi$. Moreover we investigate the regularity of the regular free boundary and
show that it has the structure of a $C^{1,\gamma}$ manifold for some $\gamma
\in (0,1)$.


title: A Clockwork Theory

abstract:
  The clockwork is a mechanism for generating light particles with
exponentially suppressed interactions in theories which contain no small
parameters at the fundamental level. We develop a general description of the
clockwork mechanism valid for scalars, fermions, gauge bosons, and gravitons.
This mechanism can be implemented with a discrete set of new fields or, in its
continuum version, through an extra spatial dimension. In both cases the
clockwork emerges as a useful tool for model-building applications. Notably,
the continuum clockwork offers a solution to the Higgs naturalness problem,
which turns out to be the same as in linear dilaton duals of Little String
Theory. We also elucidate the similarities and differences of the continuum
clockwork with large extra dimensions and warped spaces. All clockwork models,
in the discrete and continuum, exhibit novel phenomenology with a distinctive
spectrum of closely spaced resonances.


title: The Puzzling Detection of X-rays From Pluto by Chandra

abstract:
  Using Chandra ACIS-S, we have obtained imaging Xray spectrophotometry of the
Pluto system in support of the New Horizons flyby on 14 July 2015. 174 ksec of
observations were obtained on 4 visits in Feb 2014 to Aug 2015. We measured a
net signal of 6.8 counts and a noise level of 1.2 counts in a comoving 11 x 11
pixel box (100 x 100 R_Pluto) in the 0.31 to 0.60 keV passband for a detection
at > 99.95 C.L. The Pluto photons do not match the background spectrum, are
coincident with a 90% flux aperture comoving with Pluto, and are not sky source
confused. The mean 0.31 to 0.60 keV Xray power from Pluto is 200 MW, in the
midrange of Xray power levels seen for known solar system emission sources:
auroral precipitation, solar Xray scattering, and charge exchange (CXE) between
solar wind (SW) ions & atmospheric neutrals. We eliminate auroral effects as a
source, as Pluto has no known magnetic field & the New Horizons Alice UV
spectrometer detected no airglow from Pluto during the flyby. Nano-scale
atmospheric haze particles could lead to enhanced resonant scattering of solar
X-rays from Pluto, but the energy signature of the detected photons does not
match the solar spectrum and estimates of Plutos scattered Xray emission are >
100 times below the 3.9e-5 cps found in our observations. CXE emission from SW
carbon, nitrogen, and oxygen ions can produce the energy signature seen, and
the 6e25 neutral gas escape rate from Pluto deduced from New Horizons data can
support the 3.0e24 Xray photons/sec emission rate required by our observations.
Using the SW proton density and speed measured by the Solar Wind Around Pluto
(SWAP) instrument in the vicinity of Pluto at the time of the photon emissions,
we find too few SW minor ions flowing into the 11 x 11 pixel box centered on
Pluto than are needed to support the observed emission rate unless the SW is
significantly focused and enhanced in this region.


title:
To CME or not to CME? Implications of p+Pb measurements of the chiral
  magnetic effect in heavy ion collisions

abstract:
  The Chiral Magnetic Effect (CME) is a fundamental prediction of QCD, and
various observables have been proposed in heavy ion collisions to access this
physics. Recently the CMS Collaboration \cite{Khachatryan:2016got} has reported
results from p+Pb collisions at 5.02 TeV on one such observable, the
three-point correlator. The results are strikingly similar to those measured at
the same particle multiplicity in Pb+Pb collisions, which have been attributed
to the CME. This similarity, combined with two key assumptions about the
magnetic field in p+Pb collisions, presents a major challenge to the CME
picture. These two assumptions as stated in the CMS paper are (1) that the
magnetic field in p+Pb collisions is smaller than that in Pb+Pb collisions and
(2) that the magnetic field direction is uncorrelated with the flow angle. We
test these two postulates in the Monte Carlo Glauber framework and find that
the magnetic fields are not significantly smaller in central p+Pb collisions,
however the magnetic field direction and the flow angle are indeed
uncorrelated. The second finding alone gives strong evidence that the
three-point correlator signal in Pb+Pb and p+Pb is not an indication of the
CME. Similar measurements in d+Au over a range of energies accessible at RHIC
would be elucidating. In the same calculational framework, we find that even in
Pb+Pb collisions, where the magnetic field direction and the flow angle are
correlated, there exist large inhomogeneities that are on the size scale of
topological domains. These inhomogeneities need to be incorporated in any
detailed CME calculation.


title: Higher-Order Linearisability

abstract:
  Linearisability is a central notion for verifying concurrent libraries: a
given library is proven safe if its operational history can be rearranged into
a new sequential one which, in addition, satisfies a given specification.
Linearisability has been examined for libraries in which method arguments and
method results are of ground type, including libraries parameterised with such
methods. In this paper we extend linearisability to the general higher-order
setting: methods can be passed as arguments and returned as values. A library
may also depend on abstract methods of any order. We use this generalised
notion to show correctness of several higher-order example libraries.


title:
Chandra Characterization of X-ray Emission in the Young F-Star Binary
  System HD 113766

abstract:
  Using Chandra we have obtained imaging X-ray spectroscopy of the 10 to 16 Myr
old F-star binary HD 113766. We individually resolve the binary components for
the first time in the X-ray and find a total 0.3 to 2.0 keV luminosity of
2.2e29 erg/sec, consistent with previous RASS estimates. We find emission from
the easternmost, infrared-bright, dusty member HD 113766A to be only 10% that
of the western, infrared-faint member HD 113766B. There is no evidence for a
3rd late-type stellar or sub-stellar member of HD113766 with Lx > 6e25 erg s-1
within 2 arcmin of the binary pair. The ratio of the two stars Xray luminosity
is consistent with their assignments as F2V and F6V by Pecaut et al. (2012).
The emission is soft for both stars, kTApec = 0.30 to 0.50 keV, suggesting
X-rays produced by stellar rotation and/or convection in young dynamos, but not
accretion or outflow shocks which we rule out. A possible 2.8 +/- 0.15
(2{\sigma}) hr modulation in the HD 113766B X-ray emission is seen, but at very
low confidence and of unknown provenance. Stellar wind drag models
corresponding to Lx = 2e29 erg s-1 argue for a 1 mm dust particle lifetime
around HD 113766B of only 90,0000 years, suggesting that dust around HD 113766B
is quickly removed, whereas dust around HD 113766A can survive for > 1.5e6 yrs.
At 1e28 to 1e29 erg s-1 luminosity, astrobiologically important effects, like
dust warming and X-ray photolytic organic synthesis, are likely for any
circumstellar material in the HD 113766 systems.


title: High rank quadratic twists of pairs of elliptic curves

abstract:
  Given a pair of elliptic curves $E_1$ and $E_2$ over the rational field
$\mathbb Q$ whose $j$-invariants are not simultaneously 0 or 1728, Kuwata and
Wang proved the existence of infinitely many square-free rationals $d$ such
that the $d$-quadratic twists of $E_1$ and $E_2$ are both of positive rank. We
construct infinite families of pairs of elliptic curves $E_1$ and $E_2$ over
$\mathbb Q$ such that for each pair there exist infinitely many square-free
rationals $d$ for which the $d$-quadratic twists of $E_1$ and $E_2$ are both of
rank at least 2.


title: Equivariant cohomology rings of the real flag manifolds

abstract:
  We give Leray-Borel-type descriptions for the mod-$2$ and the rational
equivariant cohomology rings of the real and the oriented flag manifolds under
the canonical torus or 2-torus actions.


title:
Wasserstein Stability of the Entropy Power Inequality for Log-Concave
  Densities

abstract:
  We establish quantitative stability results for the entropy power inequality
(EPI). Specifically, we show that if uniformly log-concave densities nearly
saturate the EPI, then they must be close to Gaussian densities in the
quadratic Wasserstein distance. Further, if one of the densities is log-concave
and the other is Gaussian, then the deficit in the EPI can be controlled in
terms of the $L^1$-Wasserstein distance. As a counterpoint, an example shows
that the EPI can be unstable with respect to the quadratic Wasserstein distance
when densities are uniformly log-concave on sets of measure arbitrarily close
to one. Our stability results can be extended to non-log-concave densities,
provided certain regularity conditions are met. The proofs are based on optimal
transportation.


title: Effective Potential Theory for Diffusion in Binary Ionic Mixtures

abstract:
  Self-diffusion and interdiffusion coefficients of binary ionic mixtures are
evaluated using the Effective Potential Theory (EPT), and the predictions are
compared with the results of molecular dynamics simulations. We find that EPT
agrees with molecular dynamics from weak coupling well into the strong coupling
regime, which is a similar range of coupling strengths as previously observed
in comparisons with the one-component plasma. Within this range, typical
relative errors of approximately 20% and worst-case relative errors of
approximately 40% are observed. We also examine the Darken model, which
approximates the interdiffusion coefficients based on the self-diffusion
coefficients.


title: On rational triangles via algebraic curves

abstract:
  A rational triangle is a triangle with rational side lengths. We consider
three different families of rational triangles having a fixed side and whose
vertices are rational points in the plane. We display a one-to-one
correspondence between each family and the set of rational points of an
algebraic curve. These algebraic curves are: a curve of genus 0, an elliptic
curve, and a genus 3 curve. We study the set of rational points on each of
these curves and describe some of its rational points explicitly.


title:
Tachyonic instabilities in 2+1 dimensional Yang-Mills theory and its
  connection to Number Theory

abstract:
  We consider the $2+1$ dimensional Yang-Mills theory with gauge group
$\text{SU}(N)$ on a flat 2-torus under twisted boundary conditions. We study
the possibility of phase transitions (tachyonic instabilities) when $N$ and the
volume vary and certain chromomagnetic flux associated to the topology of the
bundle can be adjusted. Under natural assumptions about how to match the
perturbative regime and the expected confinement, we prove that the absence of
tachyonic instabilities is related to some problems in number theory, namely
the Diophantine approximation of irreducible fractions by other fractions of
smaller denominator.


title: Geometric realizations of affine Kac-Moody algebras

abstract:
  The goal of the present paper is to obtain new free field realizations of
affine Kac-Moody algebras motivated by geometric representation theory for
generalized flag manifolds of finite-dimensional semisimple Lie groups. We
provide an explicit construction of a large class of irreducible modules
associated with certain parabolic subalgebras covering all known special cases.

categories: math.RT math-ph math.AG math.FA math.MP math.OA


title: Conformational properties of active semiflexible polymers

abstract:
  The conformational properties of flexible and semiflexible polymers exposed
to active noise are studied theoretically. The noise may originate from the
interaction of the polymer with surround- ing active (Brownian) particles or
from the inherent motion of the polymer itself, which may be composed of active
Brownian particles. In the latter case, the respective monomers are indepen-
dently propelled in directions changing diffusively. For the description of the
polymer, we adopt the continuous Gaussian semiflexible polymer model.
Specifically, the finite polymer extensibility is taken into account which
turns out to be essentially for the polymer conformations. Our analytical
calculations predict a strong dependence of the relaxation times on the
activity. In particular, semi- flexible polymers exhibit a crossover from a
bending-elasticity-dominated to the flexible-polymer dynamics with increasing
activity. This leads to a significant noise-induced polymer shrinkage over a
large range of self-propulsion velocities. For large activities, the polymers
swell and their extension becomes comparable to the contour length. The scaling
properties of the mean square end-to-end distance with respect to the polymer
length and monomer activity are discussed.


title: $P$ fluxes and exotic branes

abstract:
  We consider the ${\cal N}=1$ superpotential generated in type-II orientifold
models by non-geometric fluxes. In particular, we focus on the family of $P$
fluxes, that are related by T-duality transformations to the S-dual of the $Q$
flux. We determine the general rule that transforms a given flux in this family
under a single T-duality transformation. This rule allows to derive a complete
expression for the superpotential for both the IIA and the IIB theory for the
particular case of a $T^6/[\mathbb{Z}_2 \times \mathbb{Z}_2 ]$ orientifold. We
then consider how these fluxes modify the generalised Bianchi identities. In
particular, we derive a fully consistent set of quadratic constraints coming
from the NS-NS Bianchi identities. On the other hand, the $P$ flux Bianchi
identities induce tadpoles, and we determine a set of exotic branes that can be
consistently included in order to cancel them. This is achieved by determining
a universal transformation rule under T-duality satisfied by all the branes in
string theory.


title: Microfluidic Flow of Cholesteric Liquid Crystals

abstract:
  We explore the rheology and flow-induced morphological changes of cholesteric
liquid crystal patterns subject to Poiseuille flow within a slab geometry, and
under different anchoring conditions at the wall. Our focus is particularly on
the behaviour of Cholesteric Fingers of the first kind and of Blue Phase II.
Depending on the applied pressure gradient, we observe a number of dynamic
regimes with different rheological properties. Our results provide the first
insight into the flow response of cholesteric phases with fully two- or
three-dimensional director field patterns and normal and planar degenerate
anchoring conditions as commonly realised in experiments. They are also of high
relevance for a fundamental understanding of complex liquid crystals in
confinement and an important step towards future microfluidic applications that
are based on cholesteric liquid crystals.


title:
Spectator Higgs, large-scale gauge fields and the non-minimal coupling
  to gravity

abstract:
  Even if the Higgs field does not affect the evolution of the background
geometry, its massive inhomogeneities induce large-scale gauge fields whose
energy density depends on the slow-roll parameters, on the effective scalar
mass and, last but not least, on the dimensionless coupling to the space-time
curvature. Since the non-Abelian gauge modes are screened, the non-minimal
coupling to gravity predominantly affects the evolution of the hypercharge and
electromagnetic fields. While in the case of minimal coupling the obtained
constraints are immaterial, as soon as the coupling increases beyond one fourth
the produced fields become overcritical. We chart the whole parameter space of
this qualitatively new set of bounds. Whenever the limits on the curvature
coupling are enforced, the magnetic field may still be partially relevant for
large-scale magnetogenesis and exceed $10^{-20}$ G for the benchmark scale of
the protogalactic collapse.


title: Dependent Types in Haskell: Theory and Practice

abstract:
  Haskell, as implemented in the Glasgow Haskell Compiler (GHC), has been
adding new type-level programming features for some time. Many of these
features---chiefly: generalized algebraic datatypes (GADTs), type families,
kind polymorphism, and promoted datatypes---have brought Haskell to the
doorstep of dependent types. Many dependently typed programs can even currently
be encoded, but often the constructions are painful.
  In this dissertation, I describe Dependent Haskell, which supports full
dependent types via a backward-compatible extension to today's Haskell. An
important contribution of this work is an implementation, in GHC, of a portion
of Dependent Haskell, with the rest to follow. The features I have implemented
are already released, in GHC 8.0. This dissertation contains several practical
examples of Dependent Haskell code, a full description of the differences
between Dependent Haskell and today's Haskell, a novel type-safe dependently
typed lambda-calculus (called Pico) suitable for use as an intermediate
language for compiling Dependent Haskell, and a type inference and elaboration
algorithm, Bake, that translates Dependent Haskell to type-correct Pico.


title:
Pre-inflation: origin of the Universe from a topological phase
  transition

abstract:
  I study a model which describes the birth of the universe using a global
topological phase transition with a complex manifold where the time, $\tau$, is
considered as a complex variable. Before the big bang $\tau$ is a purely
imaginary variable so that the space can be considered as Euclidean. The phase
transition from a pre-inflation to inflation is examined by studying the
dynamical rotation of the time on the complex plane. Back-reaction effects are
exactly calculated using Relativistic Quantum Geometry.


title: A geometrical approach to degenerate scalar-tensor theories

abstract:
  Degenerate scalar-tensor theories are recently proposed covariant theories of
gravity coupled with a scalar field. Despite being characterised by higher
order equations of motion, they do not propagate more than three degrees of
freedom, thanks to the existence of constraints. We discuss a geometrical
approach to degenerate scalar-tensor systems, and analyse its consequences. We
show that some of these theories emerge as a certain limit of DBI Galileons. In
absence of dynamical gravity, these systems correspond to scalar theories
enjoying a symmetry which is different from Galileon invariance. The scalar
theories have however problems concerning the propagation of fluctuations
around a time dependent background. These issues can be tamed by breaking the
symmetry by hand, or by minimally coupling the scalar with dynamical gravity in
a way that leads to degenerate scalar-tensor systems. We show that distinct
theories can be connected by a relation which generalizes Galileon duality, in
certain cases also when gravity is dynamical. We discuss some implications of
our results in concrete examples. Our findings can be helpful for assessing
stability properties and understanding the non-perturbative structure of
systems based on degenerate scalar-tensor systems.


title:
How far does small chemotactic interaction perturb the Fisher-KPP
  dynamics?

abstract:
  This paper deals with nonnegative solutions of the Neumann initial-boundary
value problem for the fully parabolic chemotaxis-growth system $
(u_{\varepsilon})_t$ $=\Delta u_{\varepsilon} - \varepsilon \nabla \cdot (
u_\varepsilon \nabla v_\varepsilon) + \mu u_\varepsilon(1 - u_\varepsilon)$, $
(v_{\varepsilon})_t=\Delta v_\varepsilon -v_\varepsilon+u_\varepsilon,$ with
positive small parameter $\varepsilon>0$ in a bounded convex domain
$\Omega\subset\mathbb{R}^n$ ($n\geq 1$) with smooth boundary. The solutions
converge to the solution $u$ to the Fisher-KPP equation as $\varepsilon\to 0$.
It is shown that for all $\mu>0$ and any suitably regular nonnegative initial
data $(u_{init},v_{init})$ there are some constants $\varepsilon_0>0$ and $C>0$
such that \[ \sup_{t>0}\|u_\varepsilon(\cdot,t)-u(\cdot,t)\|_{L^\infty(\Omega)}
\leq C\varepsilon \quad for\ all\ \varepsilon\in(0,\varepsilon_0). \]


title:
The Third Offset and a Fifth Domain? Balancing Game-Changing Innovation
  and Cyber Risk Mitigation

abstract:
  Cyber has changed the scope of the national security mission and is placing
new strains on our diplomatic, warfighting, legal, and economic/budgetary
processes. Cybersecurity processes and techniques are increasingly critical to
our warfighting missions, but they can also inhibit the pace and potential for
high impact, game-changing innovation. Throughout its history, the Navy has
shown the ability of innovation (in policy, process, and technology) to change
the game when our security is on the line. We believe the Navy is capable of
dramatically impacting not only the U.S. capabilities in cyber conflict and
information operations, but also in cyber defense and information assurance, as
well as cybersecurity for our society. While cyber risk management is
challenging, the transition from DoD Information Assurance Certification and
Accreditation Process (DIACAP) to the Risk Management Framework (RMF) has the
potential to harmonize our cybersecurity efforts with our need (and
demonstrated ability to provide) for game-changing strategies, tactics, and
technologies. We offer a foundation for the foregoing assertions and
recommendations on ways to encourage innovation in the context of effective
cyber risk management.


title: Supersymmetric deformations of 3D SCFTs from tri-sasakian truncation

abstract:
  We holographically study supersymmetric deformations of $N=3$ and $N=1$
superconformal field theories (SCFTs) in three dimensions using
four-dimensional $N=4$ gauged supergravity coupled to three-vector multiplets
with non-semisimple $SO(3)\ltimes (\mathbf{T}^3,\hat{\mathbf{T}}^3)$ gauge
group. This gauged supergravity can be obtained from a truncation of
eleven-dimensional supergravity on a tri-sasakian manifold and admits both
$N=1,3$ supersymmetric and stable non-supersymmetric $AdS_4$ critical points.
We analyze the BPS equations for $SO(3)$ singlet scalars in details and study
possible supersymmetric solutions. A number of RG flows to non-conformal field
theories and half-supersymmetric domain walls are found, and many of them can
be given analytically. Apart from these "flat" domain walls, we also consider
$AdS_3$-sliced domain wall solutions describing two-dimensional conformal
defects with $N=(1,0)$ supersymmetry within the dual $N=1$ field theory while
this type of solutions does not exist in the $N=3$ case.


title: FFLV-type monomial bases for type $B$

abstract:
  We present a combinatorial monomial basis (or, more precisely, a family of
monomial bases) in every finite-dimensional irreducible
$\mathfrak{so}_{2n+1}$-module. These bases are in many ways similar to the FFLV
bases for types $A$ and $C$. They are also defined combinatorially via sums
over Dyck paths in certain triangular grids. Our sums, however, involve weights
depending on the length of the corresponding root. Accordingly, our bases also
induce bases in certain degenerations of the modules but these degenerations
are obtained not from the filtration by PBW degree but by a weighted version
thereof.


title: An Analysis of Attacks on Blockchain Consensus

abstract:
  We present and validate a novel mathematical model of the blockchain mining
process and use it to conduct an economic evaluation of the double-spend
attack, which is fundamental to all blockchain systems. Our analysis focuses on
the value of transactions that can be secured under a conventional double-spend
attack, both with and without a concurrent eclipse attack. Our model quantifies
the importance of several factors that determine the attack's success,
including confirmation depth, attacker mining power, and any confirmation
deadline set by the merchant. In general, the security of a transaction against
a double-spend attack increases roughly logarithmically with the depth of the
block, made easier by the increasing sum of coin turned-over (between
individuals) in the blocks, but more difficult by the increasing proof of work
required. In recent blockchain data, we observed a median block turnover value
of 6 BTC. Based on this value, a merchant requiring a single confirmation is
protected against only attackers that can increase the current mining power by
1% or less. However, similar analysis shows that a merchant that requires a
much longer 72 confirmations (~12 hours) will eliminate all potential profit
for any double-spend attacker adding mining power less than 40% of the current
mining power.


title:
Leaders and followers: Quantifying consistency in spatio-temporal
  propagation patterns

abstract:
  Repetitive spatio-temporal propagation patterns are encountered in fields as
wide-ranging as climatology, social communication and network science. In
neuroscience, perfectly consistent repetitions of the same global propagation
pattern are called a synfire pattern. For any recording of sequences of
discrete events (in neuroscience terminology: sets of spike trains) the
questions arise how closely it resembles such a synfire pattern and which are
the spike trains that lead/follow. Here we address these questions and
introduce an algorithm built on two new indicators, termed SPIKE-Order and
Spike Train Order, that define the Synfire Indicator value, which allows to
sort multiple spike trains from leader to follower and to quantify the
consistency of the temporal leader-follower relationships for both the original
and the optimized sorting. We demonstrate our new approach using artificially
generated datasets before we apply it to analyze the consistency of propagation
patterns in two real datasets from neuroscience (Giant Depolarized Potentials
in mice slices) and climatology (El Ni~no sea surface temperature recordings).
The new algorithm is distinguished by conceptual and practical simplicity, low
computational cost, as well as flexibility and universality.


title: Josephson junction microwave modulators for qubit control

abstract:
  We demonstrate Josephson junction based double-balanced mixer and phase
shifter circuits operating at 6-10 GHz, and integrate these components to
implement both a monolithic amplitude/phase vector modulator and a quadrature
mixer. The devices are actuated by flux signals, dissipate no power on chip,
exhibit input saturation powers in excess of 1 nW, and provide cryogenic
microwave modulation solutions for integrated control of superconducting
qubits.


title:
Perfect matchings and Hamiltonian cycles in the preferential attachment
  model

abstract:
  In this paper, we study the existence of perfect matchings and Hamiltonian
cycles in the preferential attachment model. In this model, vertices are added
to the graph one by one, and each time a new vertex is created it establishes a
connection with $m$ random vertices selected with probabilities proportional to
their current degrees. (Constant $m$ is the only parameter of the model.) We
prove that if $m \ge 1{,}260$, then asymptotically almost surely there exists a
perfect matching. Moreover, we show that there exists a Hamiltonian cycle
asymptotically almost surely, provided that $m \ge 29{,}500$. One difficulty in
the analysis comes from the fact that vertices establish connections only with
vertices that are "older" (i.e. are created earlier in the process). However,
the main obstacle arises from the fact that edges in the preferential
attachment model are not generated independently. In view of that, we also
consider a simpler setting---sometimes called uniform attachment---in which
vertices are added one by one and each vertex connects to $m$ older vertices
selected uniformly at random and independently of all other choices. We first
investigate the existence of perfect matchings and Hamiltonian cycles in the
uniform attachment model, and then extend the argument to the preferential
attachment version.


title: Process Discovery using Inductive Miner and Decomposition

abstract:
  This report presents a submission to the Process Discovery Contest. The
contest is dedicated to the assessment of tools and techniques that discover
business process models from event logs. The objective is to compare the
efficiency of techniques to discover process models that provide a proper
balance between "overfitting" and "underfitting". In the context of the Process
Discovery Contest, process discovery is turned into a classification task with
a training set and a test set; where a process model needs to decide whether
traces are fitting or not. In this report, we first show how we use two
discovery techniques, namely: Inductive Miner and Decomposition, to discover
process models from the training set using ProM tool. Second, we show how we
use replay results to 1) check the rediscoverability of models, and to 2)
classify unseen traces (in test logs) as fitting or not. Then, we discuss the
classification results of validation logs, the complexity of discovered models,
and their impact on the selection of models for submission. The report ends
with the pictures of the submitted process models.


title: Effects of Cosmological Constant on Clustering of Galaxies

abstract:
  In this paper, we analyse the effect of the expansion of the universe on the
clustering of galaxies. We evaluate the configurational integral for
interacting system of galaxies in an expanding universe by including effects
produced by the cosmological constant. The gravitational partition function is
obtained using this configuration integral. Thermodynamic quantities,
specifically, Helmholtz free energy, entropy, internal energy, pressure and
chemical potential are also derived for this system. It is observed that they
depend on the modified clustering parameter for this system of galaxies. It is
also demonstrated that these thermodynamical quantities get corrected because
of the cosmological constant.


title:
Gauges and functional measures in quantum gravity II: Higher derivative
  gravity

abstract:
  We compute the one-loop divergences in a higher-derivative theory of gravity
including Ricci tensor squared and Ricci scalar squared terms, in addition to
the Hilbert and cosmological terms, on an (generally off-shell) Einstein
background. We work with a two-parameter family of parametrizations of the
graviton field, and a two-parameter family of gauges. We find that there are
some choices of gauge or parametrization that reduce the dependence on the
remaining parameters. The results are invariant under a recently discovered
"duality" that involves the replacement of the densitized metric by a
densitized inverse metric as the fundamental quantum variable.


title: Numerical analysis of strongly nonlinear PDEs

abstract:
  We review the construction and analysis of numerical methods for strongly
nonlinear PDEs, with an emphasis on convex and nonconvex fully nonlinear
equations and the convergence to viscosity solutions. We begin by describing a
fundamental result in this area which states that stable, consistent, and
monotone schemes converge as the discretization parameter tends to zero. We
review methodologies to construct finite difference, finite element, and
semi-Lagrangian schemes that satisfy these criteria, and, in addition, discuss
some rather novel tools that have paved the way to derive rates of convergence
within this framework.


title:
Second level semi-degenerate fields in W3 Toda theory: matrix element
  and differential equation

abstract:
  In a recent study we considered W3 Toda 4-point functions that involve matrix
elements of a primary field with the highest-weight in the adjoint
representation of sl3. We generalize this result by considering a
semi-degenerate primary field, which has one null vector at level two. We
obtain a sixth-order Fuchsian differential equation for the conformal blocks.
We discuss the presence of multiplicities, the matrix elements and the fusion
rules.


title: A note on dimers and T-graphs

abstract:
  The purpose of this note is to give a succinct summary of some basic
properties of T-graphs which arise in the study of the dimer model. We focus in
particular on the relation between the dimer model on the heaxgonal lattice
with a given slope, and the behaviour of the uniform spanning tree on the
associated T-graph. Together with the main result of the companion paper
\cite{BLR16}, the results here show Gaussian free field fluctuations for the
height function in some dimer models.


title: Spatial Relationship Based Features for Indian Sign Language Recognition

abstract:
  In this paper, the task of recognizing signs made by hearing impaired people
at sentence level has been addressed. A novel method of extracting spatial
features to capture hand movements of a signer has been proposed. Frames of a
given video of a sign are preprocessed to extract face and hand components of a
signer. The local centroids of the extracted components along with the global
centroid are exploited to extract spatial features. The concept of interval
valued type symbolic data has been explored to capture variations in the same
sign made by the different signers at different instances of time. A suitable
symbolic similarity measure is studied to establish matching between test and
reference signs and a simple nearest neighbour classifier is used to recognize
an unknown sign as one among the known signs by specifying a desired level of
threshold. An extensive experimentation is conducted on a considerably large
database of signs created by us during the course of research work in order to
evaluate the performance of the proposed system


title:
A criterion for continuity in a parameter of solutions to generic
  boundary-value problems for higher-order differential systems

abstract:
  We consider the most general class of linear boundary-value problems for
ordinary differential systems, of order $r\geq1$, whose solutions belong to the
complex space $C^{(n+r)}$, with $0\leq n\in\mathbb{Z}$. The boundary conditions
can contain derivatives of order $l$, with $r\leq l\leq n+r$, of the solutions.
We obtain a constructive criterion under which the solutions to these problems
are continuous with respect to the parameter in the normed space $C^{(n+r)}$.
We also obtain a two-sided estimate for the degree of convergence of these
solutions.


title:
Artificial Intelligence Safety and Cybersecurity: a Timeline of AI
  Failures

abstract:
  In this work, we present and analyze reported failures of artificially
intelligent systems and extrapolate our analysis to future AIs. We suggest that
both the frequency and the seriousness of future AI failures will steadily
increase. AI Safety can be improved based on ideas developed by cybersecurity
experts. For narrow AIs safety failures are at the same, moderate, level of
criticality as in cybersecurity, however for general AI, failures have a
fundamentally different impact. A single failure of a superintelligent system
may cause a catastrophic event without a chance for recovery. The goal of
cybersecurity is to reduce the number of successful attacks on the system; the
goal of AI Safety is to make sure zero attacks succeed in bypassing the safety
mechanisms. Unfortunately, such a level of performance is unachievable. Every
security system will eventually fail; there is no such thing as a 100% secure
system.


title: Stability and coercivity for toric polarizations

abstract:
  We introduce uniform K-stability and its relationship with the coercivity
property of the K-energy functional, for general polarized manifolds. Since the
automorphism groups are not necessarily finite, size of the norm measuring
uniformity should be reduced with respect to the group action. About this point
we explain that it is enough to take the reduced norm for a single sub-torus,
actually the center, in the cscK problem. Our main theorem then describes the
slope of the reduced J-functional along any torus-equivariant test
configuration. In the toric case it is shown that the uniform stability is
indeed equivalent to the coercivity of the K-energy. In the Fano manifolds case
existence of the KE metric implies the uniform stability.


title: Rapid Mixing of Hypergraph Independent Set

abstract:
  We prove that the the mixing time of the Glauber dynamics for sampling
independent sets on $n$-vertex $k$-uniform hypergraphs is $O(n\log n)$ when the
maximum degree $\Delta$ satisfies $\Delta \leq c 2^{k/2}$, improving on the
previous bound [BDK06] of $\Delta \leq k-2$. This result brings the algorithmic
bound to within a constant factor of the hardness bound of [BGG+16] which
showed that it is NP-hard to approximately count independent sets on
hypergraphs when $\Delta \geq 5 \cdot 2^{k/2}$.


title: Statistical Machine Translation for Indian Languages: Mission Hindi 2

abstract:
  This paper presents Centre for Development of Advanced Computing Mumbai's
(CDACM) submission to NLP Tools Contest on Statistical Machine Translation in
Indian Languages (ILSMT) 2015 (collocated with ICON 2015). The aim of the
contest was to collectively explore the effectiveness of Statistical Machine
Translation (SMT) while translating within Indian languages and between English
and Indian languages. In this paper, we report our work on all five language
pairs, namely Bengali-Hindi (\bnhi), Marathi-Hindi (\mrhi), Tamil-Hindi
(\tahi), Telugu-Hindi (\tehi), and English-Hindi (\enhi) for Health, Tourism,
and General domains. We have used suffix separation, compound splitting and
preordering prior to SMT training and testing.


title:
Solar Spectral Irradiance Variability in Cycle 24: Observations and
  Models

abstract:
  Utilizing the excellent stability of the Ozone Monitoring Instrument (OMI),
we characterize both short-term (solar rotation) and long-term (solar cycle)
changes of the solar spectral irradiance (SSI) between 265-500 nm during the
on-going Cycle 24. We supplement the OMI data with concurrent observations from
the GOME-2 and SORCE instruments and find fair-to-excellent, depending on
wavelength, agreement among the observations and predictions of the NRLSSI2 and
SATIRE-S models.


title:
A space-time Trefftz discontinuous Galerkin method for the acoustic wave
  equation in first-order formulation

abstract:
  We introduce a space-time Trefftz discontinuous Galerkin method for the
first-order transient acoustic wave equations in arbitrary space dimensions,
extending the one dimensional scheme of Kretzschmar et al. (2016, IMA J. Numer.
Anal., 36, 1599-1635). Test and trial discrete functions are space-time
piecewise polynomial solutions of the wave equations. We prove well-posedness
and a priori error bounds in both skeleton-based and mesh-independent norms.
The space-time formulation corresponds to an implicit time-stepping scheme, if
posed on meshes partitioned in time slabs, or to an explicit scheme, if posed
on "tent-pitched" meshes. We describe two Trefftz polynomial discrete spaces,
introduce bases for them and prove optimal, high-order $h$-convergence bounds.


title:
A first thermodynamic interpretation of the technology transfer
  activities

abstract:
  In the last years new interdisciplinary approaches to economics and social
science have been developed. A Thermodynamic approach to socio-economics has
brought to a new interdisciplinary scientific field called econophysics. Why
thermodynamic? Thermodynamic is a statistical theory for large atomic system
under constraints of energy[1] and the economy can be considered a large system
governed by complex rules. The present job proposes a new application, starting
from econophysic, passing throughout the thermodynamic laws to interpret and to
described the Technology Transfer (TT) activities. Using the definition of
economy (i.e. economy[dictionary def.] = the process or system by which goods
and services are produced, sold, and bought in a country or region) the TT can
be considered an important sub-domain of the economy and a transversal new area
of the scientific research. The TT is the process of transferring knowledge,
that uses the results from the research to produce innovation and to ensure
that scientific and technological developments could become accessible to a
wider range of users. Starting from important Universities (MIT, Stanford,
Oxford, etc) nowadays the TT is assuming a central role. It is called the third
mission, together with education and research. The importance to provide new
theories and tools to describe the TT activities and their behavior, has been
retained fundamental to support the social rapid evolution that is involving
the TT offices. The presented work uses the thermodynamic theories applying
them to Technology Transfer and starting from the concept of entropy, exergy
and anergy. The output analysis should become an help to make decision to
improve the TT activities and a better resources employment.


title:
On Fractional Linear Network Coding Solution of Multiple-Unicast
  Networks

abstract:
  It is known that there exists a multiple-unicast network which has a rate $1$
linear network coding solution if and only if the characteristic of the finite
field belongs to a given finite or co-finite set of primes. In this paper, we
show that for any non-zero positive rational number $\frac{k}{n}$, there exists
a multiple-unicast network which has a rate $\frac{k}{n}$ fractional linear
network coding solution if and only if the characteristic of the finite field
belongs to a given finite or co-finite set of primes.


title: Acylindrical Hyperbolicity of Out($W_n$)

abstract:
  We prove that the group of outer automorphisms of the free Coxeter group
$W_n$ is acylindrically hyperbolic in the sense of Osin. As an application, we
observe that any CAT(0) space admitting a geometric action by Out($W_n$) must
contain a rank-one geodesic. The theorem proceeds from expanding on a
well-known relationship between Out($W_n$) and the outer automorphism group of
free groups.


title: Energy extraction from Kerr black holes by rigidly rotating strings

abstract:
  In this paper, we show that a rigidly rotating string can extract the
rotational energy from a rotating black hole. We consider Nambu-Goto strings
stationary with respect to a corotating Killing vector with an uniform angular
velocity $\omega$ in the Kerr spacetime. We show that a necessary condition of
the energy-extraction process is that an effective horizon on the string world
sheet, which corresponds to the inner light surface, is inside the ergosphere
of the Kerr black hole and the angular velocity $\omega$ is less than that of
the black hole $\Omega_\mathrm{h}$. Furthermore, we discuss global
configurations of such strings in both of a slow-rotation limit and the
extremal Kerr case.


title: A randomized version of the Littlewood Conjecture

abstract:
  The Littlewood Conjecture in Diophantine approximation can be thought of as a
problem about covering the plane by a union of hyperbolas centered at rational
points. In this paper we consider the problem of translating the center of each
hyperbola by a random amount which depends on the denominator of the
corresponding rational. Using a randomized covering argument we prove that, not
only is this randomized version of the Littlewood Conjecture true for almost
all choices of centers, an even stronger statement with an extra factor of a
logarithm also holds.


title: Phononic four-wave mixing

abstract:
  We present the first experimental observations of phononic four-wave mixing
(FWM) in a piezoelectrically actuated free-free beam microstructure. The FWM
response is facilitated by the intrinsic coupling between a driven mode and an
auto-parametrically excited sub-harmonic mode. Motivated by the experimental
results, a dynamical model for FWM has been specified.


title:
Mean trapping time for an arbitrary node on regular hyperbranched
  polymers

abstract:
  The regular hyperbranched polymers (RHPs), also known as Vicsek fractals, are
an important family of hyperbranched structures which have attracted a wide
spread attention during the past several years. In this paper, we study the
first-passage properties for random walks on the RHPs. Firstly, we propose a
way to label all the different nodes of the RHPs and derive exact formulas to
calculate the mean first-passage time (MFPT) between any two nodes and the mean
trapping time (MTT) for any trap node. Then, we compare the trapping efficiency
between any two nodes of the RHPs by using the MTT as the measures of trapping
efficiency. We find that the central node of the RHPs is the best trapping site
and the nodes which are the farthest nodes from the central node are the worst
trapping sites. Furthermore, we find that the maximum of the MTT is about $4$
times more than the minimum of the MTT. The result is similar to the results in
the recursive fractal scale-free trees and T-fractal, but it is quite different
from that in the recursive non-fractal scale-free trees. These results can help
understanding the influences of the topological properties and trap location on
the trapping efficiency.


title:
Dynamic Nonlinear Focal Shift in Amplitude Modulated Moderately Focused
  Acoustic Beams

abstract:
  The phenomenon of the displacement of the position of the pressure, intensity
and acoustic radiation force maxima along the axis of focused acoustic beams
under increasing driving amplitudes (nonlinear focal shift) is studied for the
case of a moderately focused beam excited with continuous and 25 kHz amplitude
modulated signals, both in water and tissue. We prove that in amplitude
modulated beams the linear and nonlinear propagation effects coexist in a
semi-period of modulation, giving place to a complex dynamic behaviour, where
the singular points of the beam (peak pressure, rarefaction, intensity and
acoustic radiation force) locate at different points on axis as a function of
time. These entire phenomena are explained in terms of harmonic generation and
absorption during the propagation in a lossy nonlinear medium both, for a
continuous and an amplitude modulated beam. One of the possible applications of
the acoustic radiation force displacement is the generation of shear waves at
different locations by using a focused mono-element transducer excited with an
amplitude modulated signal.


title:
Broadband quasi perfect absorption using chirped multi-layer porous
  materials

abstract:
  This work theoretically analyzes the sound absorption properties of a chirped
multi-layer porous material including transmission, in particular showing the
broadband unidirectional absorption properties of the system. Using the
combination of the impedance matching condition and the balance between the
leakage and the intrinsic losses, the system is designed to have broadband
unidirectional and quasi perfect absorption. The transfer and scattering matrix
formalism, together with numerical simulations based on the finite element
method are used to demonstrate the results showing excellent agreement between
them. The proposed system allows to construct broadband sound absorbers with
improved absorption in the low frequency regime using less amount of material
than the complete bulk porous layer.


title: Manipulating the Polar mismatch at LaNiO3/SrTiO3 (111) Interface

abstract:
  Heteroepitaxial growth of transition-metal oxide films on the open (111)
surface of SrTiO3 results in significant restructuring due to the polar
mismatch. Monitoring the structural and composition on an atomic scale of
LaNiO3/SrTiO3 (111) interface as a function of processing conditions has
enabled the avoidance of the expected polar catastrophe. Using atomically
resolved transmission electron microscopy and spectroscopy as well as Low
energy electron diffraction, the structure of the thin film, from interface to
the surface, has been studied. In this paper, we show that the proper
processing can lead to a structure that is ordered, coherent with the substrate
without intermediate structural phase. Angle-resolved X-ray photoemission
spectroscopy shows that the oxygen content of thin films increases with the
film thickness, indicating that the polar mismatch is avoided by the presence
of oxygen vacancies.


title:
Longitudinal LASSO: Jointly Learning Features and Temporal Contingency
  for Outcome Prediction

abstract:
  Longitudinal analysis is important in many disciplines, such as the study of
behavioral transitions in social science. Only very recently, feature selection
has drawn adequate attention in the context of longitudinal modeling. Standard
techniques, such as generalized estimating equations, have been modified to
select features by imposing sparsity-inducing regularizers. However, they do
not explicitly model how a dependent variable relies on features measured at
proximal time points. Recent graphical Granger modeling can select features in
lagged time points but ignores the temporal correlations within an individual's
repeated measurements. We propose an approach to automatically and
simultaneously determine both the relevant features and the relevant temporal
points that impact the current outcome of the dependent variable. Meanwhile,
the proposed model takes into account the non-{\em i.i.d} nature of the data by
estimating the within-individual correlations. This approach decomposes model
parameters into a summation of two components and imposes separate block-wise
LASSO penalties to each component when building a linear model in terms of the
past $\tau$ measurements of features. One component is used to select features
whereas the other is used to select temporal contingent points. An accelerated
gradient descent algorithm is developed to efficiently solve the related
optimization problem with detailed convergence analysis and asymptotic
analysis. Computational results on both synthetic and real world problems
demonstrate the superior performance of the proposed approach over existing
techniques.


title:
Phase decomposition in an Fe-Cr alloy at 402 deg C: M\"ossbauer
  spectroscopic study

abstract:
  Phase separation in strained and strain-free samples of Fe84.85Cr15.15
induced by an isothermal annealing at 402 deg C up to 3888 h was studied by
means of the Mossbauer spectroscopy. The measured Fe-site spectra were analyzed
with two different procedures viz. a hyperfine field distribution and a
two-shell superposition methods. Information relevant to the kinetics of the
separation process, concentration of Cr in Fe-rich phase, short-range ordering
and magnetic texture was obtained based on values of spectral parameters. In
particular, the following quantities pertinent to the kinetics were found: the
activation energy, equal to 1666 kJ per mol for the strained sample, and to
1388 kJ per mol for the strain-relaxed one, the Avrami exponent n=2.5(2) for
both samples, the rate constant equal to 0.0011(1) for the strained and to
0.0028(1) per hour for the strained-free samples, respectively. The
concentration of Cr in the Fe-rich phase was revealed to be 11.6(4) at. % for
the strained sample, and to 13.2(4) at.% for the strain-free one. Significant
differences in the values of the short-range parameters were revealed for the
two samples. An average angle between the magnetization vector and the normal
to the sample surface was equal to 52.7 deg for the strained sample, and to
57.5 deg for the strain-relaxed one.


title:
Savu: A Python-based, MPI Framework for Simultaneous Processing of
  Multiple, N-dimensional, Large Tomography Datasets

abstract:
  Diamond Light Source (DLS), the UK synchrotron facility, attracts scientists
from across the world to perform ground-breaking x-ray experiments. With over
3000 scientific users per year, vast amounts of data are collected across the
experimental beamlines, with the highest volume of data collected during
tomographic imaging experiments. A growing interest in tomography as an imaging
technique, has led to an expansion in the range of experiments performed, in
addition to a growth in the size of the data per experiment.
  Savu is a portable, flexible, scientific processing pipeline capable of
processing multiple, n-dimensional datasets in serial on a PC, or in parallel
across a cluster. Developed at DLS, and successfully deployed across the
beamlines, it uses a modular plugin format to enable experiment-specific
processing and utilises parallel HDF5 to remove RAM restrictions. The Savu
design, described throughout this paper, focuses on easy integration of
existing and new functionality, flexibility and ease of use for users and
developers alike.


title:
Does a Differentiated, Carbonate-Rich, Rocky Object Pollute the White
  Dwarf SDSSJ104341.53+085558.2?

abstract:
  We present spectroscopic observations of the dust- and gas-enshrouded,
polluted, single white dwarf star SDSSJ104341.53+085558.2 (hereafter
SDSSJ1043+0855). Hubble Space Telescope Cosmic Origins Spectrograph
far-ultraviolet spectra combined with deep Keck HIRES optical spectroscopy
reveal the elements C, O, Mg, Al, Si, P, S, Ca, Fe, and Ni and enable useful
limits for Sc, Ti, V, Cr, and Mn in the photosphere of SDSSJ1043+0855. From
this suite of elements we determine that the parent body being accreted by
SDSSJ1043+0855 is similar to the silicate Moon or the outer layers of Earth in
that it is rocky and iron-poor. Combining this with comparison to other heavily
polluted white dwarf stars, we are able to identify the material being accreted
by SDSSJ1043+0855 as likely to have come from the outermost layers of a
differentiated object. Furthermore, we present evidence that some polluted
white dwarfs (including SDSSJ1043+0855) allow us to examine the structure of
differentiated extrasolar rocky bodies. Enhanced levels of carbon in the body
polluting SDSSJ1043+0855 relative to the Earth-Moon system can be explained
with a model where a significant amount of the accreted rocky minerals took the
form of carbonates; specifically, through this model the accreted material
could be up to 9% calcium-carbonate by mass.


title:
Strong modulation of spin currents in bilayer graphene by static and
  fluctuating proximity exchange fields

abstract:
  Two dimensional (2D) materials provide a unique platform to explore the full
potential of magnetic proximity driven phenomena, which can be further used for
applications in next generation spintronic devices. Of particular interest is
to understand and control spin currents in graphene by the magnetic exchange
field of a nearby ferromagnetic material in graphene/ferromagnetic-insulator
(FMI) heterostructures. Here, we present the experimental study showing the
strong modulation of spin currents in graphene layers by controlling the
direction of the exchange field due to FMI magnetization. Owing to clean
interfaces, a strong magnetic exchange coupling leads to the experimental
observation of complete spin modulation at low externally applied magnetic
fields in short graphene channels. Additionally, we discover that the graphene
spin current can be fully dephased by randomly fluctuating exchange fields.
This is manifested as an unusually strong temperature dependence of the
non-local spin signals in graphene, which is due to spin relaxation by
thermally-induced transverse fluctuations of the FMI magnetization.


title:
Single measurement experimental data for an inverse medium problem
  inverted by a multi-frequency globally convergent numerical method

abstract:
  The recently developed globally convergent numerical method for an inverse
medium problem for the Helmholtz equation is tested on experimental data. The
data were originally collected in the time domain, whereas the method works in
the frequency domain with the multi-frequency data. Due to a huge discrepancy
between the collected and computationally simulated data, the straightforward
Fourier transform of the experimental data does not work. Hence, it is
necessary to develop a heuristic data preprocessing procedure. This procedure
is described. The preprocessed data are used as the input for the inversion
algorithm. Numerical results demonstrate good accuracy in the reconstruction of
both refracive indices and locations of targets. Furthermore, the
reconstruction errors for refractive indices of dielectric targets are
significantly less than errors of a posteriori direct measurements.


title: Four-dimensional black holes in Einsteinian cubic gravity

abstract:
  We construct static and spherically symmetric generalizations of the
Schwarzschild- and Reissner-Nordstr\"om-(Anti-)de Sitter (RN-(A)dS) black-hole
solutions in four-dimensional Einsteinian cubic gravity (ECG). The solutions
are determined by a single blackening factor which satisfies a non-linear
second-order differential equation. Interestingly, we are able to compute
independently the Hawking temperature $T$, the Wald entropy $\mathsf{S}$ and
the Abbott-Deser mass $M$ of the solutions analytically as functions of the
horizon radius and the ECG coupling constant $\lambda$. Using these we show
that the first law of black-hole mechanics is exactly satisfied. Some of the
solutions have positive specific heat, which makes them thermodynamically
stable, even in the uncharged and asymptotically flat case. Further, we claim
that, up to cubic order in curvature, ECG is the most general four-dimensional
theory of gravity which allows for non-trivial single-blackening factor
generalizations of Schwarzschild- and RN-(A)dS which reduce to the usual
Einstein gravity solutions when the corresponding higher-order couplings are
set to zero.


title: Bounded Model Checking and Feature Omission Diversity

abstract:
  In this paper we introduce a novel way to speed up the discovery of
counterexamples in bounded model checking, based on parallel runs over versions
of a system in which features have been randomly disabled. As shown in previous
work, adding constraints to a bounded model checking problem can reduce the
size of the verification problem and dramatically decrease the time required to
find counterexample. Adapting a technique developed in software testing to this
problem provides a simple way to produce useful partial verification problems,
with a resulting decrease in average time until a counterexample is produced.
If no counterexample is found, partial verification results can also be useful
in practice.


title:
Exact solution of the classical dimer model on a triangular lattice:
  Monomer-monomer correlations

abstract:
  We obtain an asymptotic formula, as $n\to\infty$, for the monomer-monomer
correlation function $K_2(x,y)$ in the classical dimer model on a triangular
lattice, with the horizontal and vertical weights $w_h=w_v=1$ and the diagonal
weight $w_d=t>0$, where $x$ and $y$ are sites $n$ spaces apart in adjacent
rows.
  We find that $t_c=\frac{1}{2}$ is a critical value of $t$. We prove that in
the subcritical case, $0<t<\frac{1}{2}$, as $n\to\infty$,
$K_2(x,y)=K_2(\infty)\left[1-\frac{e^{-n/\xi}}{n}\,\Big(C_1+C_2(-1)^n+\mathcal
O(n^{-1})\Big)\right]$, with explicit formulae for $K_2(\infty)$, $\xi$, $C_1$,
and $C_2$. In the supercritical case, $\frac{1}{2} < t < 1$, we prove that as
$n\to\infty$, $K_2(x,y)=K_2(\infty)\Bigg[1- \frac{e^{-n/\xi}}{n}\,
\Big(C_1\cos(\omega n+\varphi_1)+C_2(-1)^n\cos(\omega n+\varphi_2)+
C_3+C_4(-1)^n$ $+\mathcal O(n^{-1})\Big)\Bigg]$, with explicit formulae for
$K_2(\infty)$, $\xi$, $\omega$, and $C_1$, $C_2$, $C_3$, $C_4$, $\varphi_1$,
$\varphi_2$. The proof is based on an extension of the
Borodin-Okounkov-Case-Geronimo formula to block Toeplitz determinants and on an
asymptotic analysis of the Fredholm determinants in hand.


title:
Phaseless quantum Monte-Carlo approach to strongly correlated
  superconductors with stochastic Hartree-Fock-Bogoliubov wavefunctions

abstract:
  The so-called phaseless quantum Monte-Carlo method currently offers one of
the best performing theoretical framework to investigate interacting Fermi
systems. It allows to extract an approximate ground-state wavefunction by
averaging independent-particle states undergoing a Brownian motion in
imaginary-time. Here, we extend the approach to a random walk in the space of
Hartree-Fock-Bogoliubov (HFB) vacua that are better suited for superconducting
or superfluid systems. Well-controlled statistical errors are ensured by
constraining stochastic paths with the help of a trial wavefunction, also
guiding the dynamics and in the form of a linear combination of HFB ans\"atze.
Estimates for the observables are reconstructed through an extension of Wick's
theorem to matrix elements between HFB product states. The usual combinatory
complexity associated to the application of this theorem for four- and more-
body operators is bypassed with a compact expression in terms of Pfaffians. The
limiting case of a stochastic motion within Slater determinants but guided with
HFB trial wavefunctions is also considered. Finally, exploratory results for
the spin polarized Hubbard model in the attractive regime are presented.


title: Positive Legendrian isotopies and Floer Theory

abstract:
  Positive loops of Legendrian embeddings are examined from the point of view
of Floer homology of Lagrangian cobordisms. This leads to new obstructions to
the existence of a positive loop containing a given Legendrian, expressed in
terms of the Legendrian contact homology of the Legendrian submanifold. As
applications, old and new examples of orderable contact manifolds are obtained
and discussed. We also show that contact manifolds admitting a filling of a
Liouville domain with non-zero symplectic homology is strongly orderable in the
sense of Liu.


title:
Orientability and fundamental classes of Alexandrov spaces with
  applications

abstract:
  In the present paper, we consider several valid notions of orientability of
Alexandov spaces and prove that all such conditions are equivalent. Further, we
give topological and geometric applications of the orientability. In
particular, a Poincar\'e-type duality theorem is proved. As a corollary to the
duality theorem, we also prove that if a closed Alexandrov space admits a
positive curvature bound in a synthetic sense, then its codimension one
homology vanishes. Further, we obtain a filling radius inequality for closed
orientable Alexandrov spaces.


title: Origin of third harmonic generation in plasmonic nanoantennas

abstract:
  Plasmonic nanoantennas have been recently proposed to boost nonlinear optical
processes. In a metal dipole nanoantenna with a dielectric nanoparticle placed
in the gap, the linear field enhancement can be exploited to enhance third
harmonic emission. Since both metals and dielectrics exhibit nonlinearity, the
nonlinear far-field contains contributions from each, and the impossibility of
measuring these contributions separately has led to seemingly contradictory
interpretations about the origin of the nonlinear emission. We determine that
the origin of the third harmonic from metal-dielectric dipole nanoantennas
depends on nanoantenna design, and in particular, the width. We find that the
emission from gold dominates in thin threadlike nanoantennas, whereas the
emission from the gap material dominates in wider nanoantennas. We also find
that monopole nanoantennas perform better than dipoles having the same width,
and due to their simplicity should be preferred in many applications.


title:
Improved Upper Bounds on Systematic-Length for Linear Minimum Storage
  Regenerating Codes

abstract:
  In this paper, we revisit the problem of finding the longest
systematic-length $k$ for a linear minimum storage regenerating (MSR) code with
optimal repair of only systematic part, for a given per-node storage capacity
$l$ and an arbitrary number of parity nodes $r$. We study the problem by
following a geometric analysis of linear subspaces and operators. First, a
simple quadratic bound is given, which implies that $k=r+2$ is the largest
number of systematic nodes in the \emph{scalar} scenario. Second, an
$r$-based-log bound is derived, which is superior to the upper bound on
log-base $2$ in the prior work. Finally, an explicit upper bound depending on
the value of $\frac{r^2}{l}$ is introduced, which further extends the
corresponding result in the literature.


title: Multisets in Type Theory

abstract:
  A multiset consists of elements, but the notion of a multiset is
distinguished from that of a set by carrying information of how many times each
element occurs in a given multiset. In this work we will investigate the notion
of iterative multisets, where multisets are iteratively built up from other
multisets, in the context Martin-L\"of Type Theory, in the presence of
Voevodsky's Univalence Axiom.
  Aczel 1978 introduced a model of constructive set theory in type theory,
using a W-type quantifying over a universe, and an inductively defined
equivalence relation on it. Our investigation takes this W-type and instead
considers the identity type on it, which can be computed from the Univalence
Axiom. Our thesis is that this gives a model of multisets. In order to
demonstrate this, we adapt axioms of constructive set theory to multisets, and
show that they hold for our model.


title: Muon bundles from extensive air showers

abstract:
  In this talk we present a possible explanation of the presence of high muon
multiplicity events registered recenty by CERN ALICE experiment in its
dedicated cosmic ray run.


title: Constraints on the optical depth of galaxy groups and clusters

abstract:
  Future data from galaxy redshift surveys, combined with high-resolutions maps
of the cosmic microwave background, will enable measurements of the pairwise
kinematic Sunyaev-Zel'dovich (kSZ) signal with unprecedented statistical
significance. This signal probes the matter-velocity correlation function,
scaled by the average optical depth ($\tau$) of the galaxy groups and clusters
in the sample, and is thus of fundamental importance for cosmology. However, in
order to translate pairwise kSZ measurements into cosmological constraints,
external constraints on $\tau$ are necessary. In this work, we present a new
model for the intra-cluster medium, which takes into account star-formation,
feedback, non-thermal pressure, and gas cooling. Our semi-analytic model is
computationally efficient and can reproduce results of recent hydrodynamical
simulations of galaxy cluster formation. By calibrating the model using recent
X-ray measurements of gas density profiles of clusters and $M_{\mathrm{gas}}-M$
relations of groups and clusters, we show that the integrated $\tau$ is
constrained to better than 6% (with a confidence level of 95%), which sets the
tightest constraints on the external prior on the optical depth of groups and
clusters reported in the literature to date. Our strong prior on $\tau$ should
significantly improve cosmological constraints derived from future pairwise kSZ
measurements and shed new insights into the nature of dark energy, modified
gravity, and neutrino mass.


title: Efficient Polar Code Construction for Higher-Order Modulation

abstract:
  An efficient algorithm for the construction of polar codes for higher-order
modulation is presented based on information-theoretic principles. The bit
reliabilities after successive demapping are estimated using the LM-rate, an
achievable rate for mismatched decoding. The successive demapper bit channels
are then replaced by binary input Additive White Gaussian Noise (biAWGN)
surrogate channels and polar codes are constructed using the Gaussian
approximation (GA). This LM-rate Demapper GA (LM-DGA) construction is used to
construct polar codes for several demapping strategies proposed in literature.
For all considered demappers, the LM-DGA constructed polar codes have the same
performance as polar codes constructed by Monte Carlo (MC) simulation. The
proposed LM-DGA construction is much faster than the MC construction. For
64-QAM, spectral efficiency 3 bits/s/Hz, and block length 1536 bits, simulation
results show that LM-DGA constructed polar codes with cyclic redundancy check
and successive cancellation list decoding are 1 dB more power efficient than
state-of-the-art AR4JA low-density parity-check codes.


title:
Quantum spin dynamics in Fock space following quenches: Caustics and
  vortices

abstract:
  Caustics occur widely in dynamics and take on shapes classified by
catastrophe theory. At finite wavelengths they produce interference patterns
containing networks of vortices (phase singularities). Here we investigate
caustics in quantized fields, focusing on the collective dynamics of quantum
spins. We show that, following a quench, caustics are generated in the Fock
space amplitudes specifying the many-body configuration and which are
accessible in experiments with cold atoms, ions or photons. The granularity of
quantum fields removes all singularities, including phase singularities,
converting point vortices into nonlocal vortices that annihilate in pairs as
the quantization scale is increased. Furthermore, the continuous scaling laws
of wave catastrophes are replaced by discrete versions. Such `quantum
catastrophes' are expected to be universal dynamical features of quantized
fields.


title:
New Construction of Eigenstates and Separation of Variables for SU(N)
  Quantum Spin Chains

abstract:
  We conjecture a new way to construct eigenstates of integrable XXX quantum
spin chains with SU(N) symmetry. The states are built by repeatedly acting on
the vacuum with a single operator Bgood(u) evaluated at the Bethe roots. Our
proposal serves as a compact alternative to the usual nested algebraic Bethe
ansatz. Furthermore, the roots of this operator give the separated variables of
the model, explicitly generalizing Sklyanin's approach to the SU(N) case. We
present many tests of the conjecture and prove it in several special cases. We
focus on rational spin chains with fundamental representation at each site, but
expect many of the results to be valid more generally.

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


title: Log canonical models of elliptic surfaces

abstract:
  We give a classification of the log canonical models of elliptic surface
pairs consisting of an elliptic fibration, a section, and a weighted sum of
marked fibers. In particular, we show how the log canonical models depend on
the choice of the weights. We describe a wall and chamber decomposition of the
space of weights based on how the log canonical model changes. In addition, we
give a generalized formula for the canonical bundle of an elliptic surface with
section and marked fibers. This is the first step in constructing
compactifcations of moduli spaces of elliptic surfaces using the minimal model
program.


title:
The NSVZ scheme for ${\cal N}=1$ SQED with $N_f$ flavors, regularized by
  the dimensional reduction, in the three-loop approximation

abstract:
  At the three-loop level we analyze, how the NSVZ relation appears for ${\cal
N}=1$ SQED regularized by the dimensional reduction. This is done by the method
analogous to the one which was earlier used for the theories regularized by
higher derivatives. Within the dimensional technique, the loop integrals cannot
be written as integrals of double total derivatives. However, similar
structures can be written in the considered approximation and are taken as a
starting point. Then we demonstrate that, unlike the higher derivative
regularization, the NSVZ relation is not valid for the renormalization group
functions defined in terms of the bare coupling constant. However, for the
renormalization group functions defined in terms of the renormalized coupling
constant, it is possible to impose boundary conditions to the renormalization
constants giving the NSVZ scheme in the three-loop order. They are similar to
the all-loop ones defining the NSVZ scheme obtained with the higher derivative
regularization, but are more complicated. The NSVZ schemes constructed with the
dimensional reduction and with the higher derivative regularization are related
by a finite renormalization in the considered approximation.


title: Parallelizable sparse inverse formulation Gaussian processes (SpInGP)

abstract:
  We propose a parallelizable sparse inverse formulation Gaussian process
(SpInGP) for temporal models. It uses a sparse precision GP formulation and
sparse matrix routines to speed up the computations. Due to the state-space
formulation used in the algorithm, the time complexity of the basic SpInGP is
linear, and because all the computations are parallelizable, the parallel form
of the algorithm is sublinear in the number of data points. We provide example
algorithms to implement the sparse matrix routines and experimentally test the
method using both simulated and real data.


title:
Modeling pressure distribution and heat in the body tissue and extract
  the relationship between them in order to improve treatment planning in HIFU

abstract:
  In high intensity focused ultrasound (HIFU) systems using non-ionizing
methods in cancer treatment, if the device is applied to the body externally,
the HIFU beam can damage nearby healthy tissues and burn skin due to lack of
knowledge about the viscoelastic properties of patient tissue and failure to
consider the physical properties of tissue in treatment planning. Addressing
this problem by using various methods, such as MRI or ultrasound, elastography
can effectively measure visco-elastic properties of tissue and fits within the
pattern of stimulation and total treatment planning. In this paper, in a linear
path of HIFU propagation, and by considering the smallest part of the path,
including voxel with three mechanical elements of mass, spring and damper,
which represents the properties of viscoelasticity of tissue, by creating waves
of HIFU in the wire environment of MATLAB mechanics and stimulating these
elements, pressure and heat transfer due to stimulation in the hypothetical
voxel was obtained. Through the repeatability of these three-dimensional
elements, tissue is created. The measurement was performed on three layers. The
values of these elements for liver tissue and kidney of sheep in a practical
example and outside the body are measured, and pressure and heat for three
layers of liver and kidney tissue of an organism were obtained by applying
ultrasound signals with a designed model. This action is repeated in three
different directions, and the results are then compared with simulation
software for ultrasound, as a reference to U.S. Food and Drug Administration
(FDA) measures for HIFU, as well as comparisons of results with an operational
method for an HIFU cell.


title: On wounded constituents in nuclear collisions

abstract:
  In this talk we summarize the main results of our recent paper, Phys. Rev.
C94, 014902, where we explore predictions of the wounded quark model for
particle production and the properties of the initial state formed in
ultra-relativistic collisions of atomic nuclei.


title: Pressure-induced superconductivity in the giant Rashba system BiTeI

abstract:
  At ambient pressure, BiTeI is the first material found to exhibit a giant
Rashba splitting of the bulk electronic bands. At low pressures, BiTeI
undergoes a transition from trivial insulator to topological insulator. At
still higher pressures, two structural transitions are known to occur. We have
carried out a series of electrical resistivity and AC magnetic susceptibility
measurements on BiTeI at pressure up to ~40 GPa in an effort to characterize
the properties of the high-pressure phases. A previous calculation found that
the high-pressure orthorhombic P4/nmm structure BiTeI is a metal. We find that
this structure is superconducting with Tc values as high as 6 K. AC magnetic
susceptibility measurements support the bulk nature of the superconductivity.
Using electronic structure and phonon calculations, we compute Tc and find that
our data is consistent with phonon-mediated superconductivity.


title: Parameterized Post-Newtonian Cosmology

abstract:
  Einstein's theory of gravity has been extensively tested on solar system
scales, and for isolated astrophysical systems, using the perturbative
framework known as the parameterized post-Newtonian (PPN) formalism. This
framework is designed for use in the weak-field and slow-motion limit of
gravity, and can be used to constrain a large class of metric theories of
gravity with data collected from the aforementioned systems. Given the
potential of future surveys to probe cosmological scales to high precision, it
is a topic of much contemporary interest to construct a similar framework to
link Einstein's theory of gravity and its alternatives to observations on
cosmological scales. Our approach to this problem is to adapt and extend the
existing PPN formalism for use in cosmology. We derive a set of equations that
use the same parameters to consistently model both weak fields and cosmology.
This allows us to parameterize a large class of modified theories of gravity
and dark energy models on cosmological scales, using just four functions of
time. These four functions can be directly linked to the background expansion
of the universe, first-order cosmological perturbations, and the weak-field
limit of the theory. They also reduce to the standard PPN parameters on solar
system scales. We illustrate how dark energy models and scalar-tensor and
vector-tensor theories of gravity fit into this framework, which we refer to as
"parameterized post-Newtonian cosmology" (PPNC).


title: Quantum electrodynamic approach to the conductivity of gapped graphene

abstract:
  The electrical conductivity of graphene with a nonzero mass-gap parameter is
investigated starting from the first principles of quantum electrodynamics in
(2+1)-dimensional space-time at any temperature. The formalism of the
polarization tensor defined over the entire plane of complex frequency is used.
At zero temperature we reproduce the results for both real and imaginary parts
of the conductivity, obtained previously in the local approximation, and
generalize them taking into account the effects of nonlocality. At nonzero
temperature the exact analytic expressions for real and imaginary parts of the
longitudinal and transverse conductivities of gapped graphene are derived, as
well as their local limits and approximate expressions in several asymptotic
regimes. Specifically, a simple local result for the real part of conductivity
of gapped graphene valid at any temperature is obtained. According to our
results, the real part of the conductivity is not equal to zero for frequencies
exceeding the width of the gap and goes to the universal conductivity with
increasing frequency. The imaginary part of conductivity of gapped graphene
varies from infinity at zero frequency to minus infinity at the frequency
defined by the gap parameter and then goes to zero with further increase of
frequency. The analytic expressions are accompanied by the results of numerical
computations. Possible future generalization of the used formalism is
discussed.