title: Extracting sigma_effective from the CDF gamma+3jets measurement

abstract:
  In their 1997 paper, CDF measured sigma_effective, the normalization factor
that relates the cross section for double parton scattering to the product of
the inclusive cross sections of the two individual scatters, in a model in
which they are assumed to be independent. In his 2007 paper, Treleani pointed
out that CDF used a non-standard definition, in which the double parton
scattering cross section corresponds to exactly two scatters, rather than the
more conventional one in which it is the inclusive two-scatter cross section.
He also estimated the correction from one definition to the other, to give a
corrected value of sigma_effective. Treleani's form would be correct under the
assumption that CDF were able to uniquely identify and count the number of
scatters in an event, which is certainly not the case. In this publication we
consider CDF's event definition in more detail to provide an improved
correction.


title: Clonal interference and Muller's ratchet in spatial habitats

abstract:
  Competition between independently arising beneficial mutations is enhanced in
spatial populations due to the linear rather than exponential growth of clones.
Recent theoretical studies have pointed out that the resulting fitness dynamics
is analogous to a surface growth process, where new layers nucleate and spread
stochastically, leading to the build up of scale-invariant roughness. This
scenario differs qualitatively from the standard view of adaptation in that the
speed of adaptation becomes independent of population size while the fitness
variance does not. Here we exploit recent progress in the understanding of
surface growth processes to obtain precise predictions for the universal,
non-Gaussian shape of the fitness distribution for one-dimensional habitats,
which are verified by simulations. When the mutations are deleterious rather
than beneficial the problem becomes a spatial version of Muller's ratchet. In
contrast to the case of well-mixed populations, the rate of fitness decline
remains finite even in the limit of an infinite habitat, provided the ratio
$U_d/s^2$ between the deleterious mutation rate and the square of the
(negative) selection coefficient is sufficiently large. Using again an analogy
to surface growth models we show that the transition between the stationary and
the moving state of the ratchet is governed by directed percolation.


title: Existence problems for the $p$-Laplacian

abstract:
  We consider a number of boundary value problems involving the $p$-Laplacian.
The model case is $-\Delta_p u=V|u|^{p-2}u$ for $u\in W_0^{1,2}(D)$ with $D$ a
bounded domain in ${\bf R}^n$. We derive necessary conditions for the existence
of nontrivial solutions. These conditions usually involve a lower bound for a
product of powers of the norm of $V$, the measure of $D$, and a sharp Sobolev
constant. In most cases, these inequalities are best possible. Applications to
non-linear eigenvalue problems are also discussed.


title: An Integral View of Fast Shocks around Supernova 1006

abstract:
  Supernova remnants are among the most spectacular examples of astrophysical
pistons in our cosmic neighborhood. The gas expelled by the supernova explosion
is launched with velocities ~ 1000 km/s into the ambient, tenuous interstellar
medium, producing shocks that excite hydrogen lines. We have used an optical
integral-field spectrograph to obtain high-resolution spatial-spectral maps
that allow us to study in detail the shocks in the northwestern rim of
supernova 1006. The two-component H\alpha\ line is detected at 133 sky
locations. Variations in the broad line widths and the broad-to-narrow line
intensity ratios across tens of atomic mean free paths suggest the presence of
suprathermal protons, the potential seed particles for generating high-energy
cosmic-rays.


title: A numerical exploration of Miranda's dynamical history

abstract:
  The Uranian satellite Miranda presents a high inclination (4.338{\deg}) and
evidences of resurfacing. It is accepted since 20 years (e.g. Tittemore and
Wisdom 1989, Malhotra and Dermott 1990) that this inclination is due to the
past trapping into the 3:1 resonance with Umbriel. These last years there is a
renewal of interest for the Uranian system since the Hubble Space Telescope
permitted the detection of an inner system of rings and small embedded
satellites, their dynamics being of course ruled by the main satellites. For
this reason, we here propose to revisit the long-term dynamics of Miranda,
using modern tools like intensive computing facilities and new chaos indicators
(MEGNO and frequency map analysis). As in the previous studies, we find the
resonance responsible for the inclination of Miranda and the secondary
resonances associated, likely to have stopped the rise of Miranda's inclination
at 4.5{\deg}. Moreover, we get other trajectories in which this inclination
reaches 7{\deg}. We also propose an analytical study of the secondary
resonances associated, based on the study by Moons and Henrard (1993).


title: Cosmological Solutions of a Nonlocal Model with a Perfect Fluid

abstract:
  A nonlocal gravity model which does not assume the existence of a new
dimensional parameter in the action and includes a function $f(\Box^{-1} R)$,
with $\Box$ the d'Alembertian operator, is studied. By specifying an
exponential form for the function f and including a matter sector with a
constant equation of state parameter, all available power-law solutions in the
Jordan frame are obtained. New power-law solutions in the Einstein frame are
also probed. Furthermore, the relationship between power-law solutions in both
frames, established through conformal transformation, is substantially
clarified. The correspondence between power-law solutions in these two frames
is proven to be a very useful tool in order to obtain new solutions in the
Einstein frame.


title: A simplified view of blazars: the gamma-ray case

abstract:
  We have recently proposed a new simplified scenario where blazars are
classified as flat-spectrum radio quasars (FSRQs) or BL Lacs according to the
prescriptions of unified schemes, and to a varying combination of Doppler
boosted radiation from the jet, emission from the accretion disk, the broad
line region, and light from the host galaxy. Here we extend our approach,
previously applied to radio and X-ray surveys, to the gamma-ray band and,
through detailed Monte Carlo simulations, compare our predictions to Fermi-LAT
survey data. Our simulations are in remarkable agreement with the overall
observational results, including the percentages of BL Lacs and FSRQs, the
fraction of redshift-less objects, and the redshift, synchrotron peak, and
gamma-ray spectral index distributions. The strength and large scatter of the
oft-debated observed Gamma-ray -- radio flux density correlation is also
reproduced. In addition, we predict that almost 3/4 of Fermi-LAT BL Lacs, and
basically all of those without redshift determination, are actually FSRQs with
their emission lines swamped by the non-thermal continuum and as such should be
considered. Finally, several of the currently unassociated high Galactic
latitude Fermi sources are expected to be radio-faint blazars displaying a pure
elliptical galaxy optical spectrum.


title: Streaming Data from HDD to GPUs for Sustained Peak Performance

abstract:
  In the context of the genome-wide association studies (GWAS), one has to
solve long sequences of generalized least-squares problems; such a task has two
limiting factors: execution time --often in the range of days or weeks-- and
data management --data sets in the order of Terabytes. We present an algorithm
that obviates both issues. By pipelining the computation, and thanks to a
sophisticated transfer strategy, we stream data from hard disk to main memory
to GPUs and achieve sustained peak performance; with respect to a
highly-optimized CPU implementation, our algorithm shows a speedup of 2.6x.
Moreover, the approach lends itself to multiple GPUs and attains almost perfect
scalability. When using 4 GPUs, we observe speedups of 9x over the
aforementioned implementation, and 488x over a widespread biology library.


title:
Traveling Wave Solutions in a Reaction-Diffusion Model for Criminal
  Activity

abstract:
  We study a reaction-diffusion system of partial differential equations, which
can be taken to be a basic model for criminal activity. We show that the
assumption of a populations natural tendency towards crime significantly
changes the long-time behavior of criminal activity patterns. Under the right
assumptions on these natural tendencies we first show that there exists
traveling wave solutions connecting zones with no criminal activity and zones
with high criminal activity, known as hotspots. This corresponds to an invasion
of criminal activity onto all space. Second, we study the problem of preventing
such invasions by employing a finite number of resources that reduce the payoff
committing a crime in a finite region. We make the concept of wave propagation
mathematically rigorous in this situation by proving the existence of entire
solutions that approach traveling waves as time approaches negative infinity.
Furthermore, we characterize the minimum amount of resources necessary to
prevent the invasion in the case when prevention is possible. Finally, we apply
our theory to what is commonly known as the gap problem in the excitable media
literature, proving existing conjectures in the literature.


title: A WISE view of novae

abstract:
  We present the result of trawling through the WISE archive for data on
classical and recurrent novae. The data show a variety of spectral energy
distributions, including stellar photospheres, dust and probable line emission.
During the mission WISE also detected some novae which erupted subsequent to
the survey, providing information about the progenitor systems.


title: Minimal support results for Schr\"odinger equations

abstract:
  We consider a number of linear and non-linear boundary value problems
involving generalized Schr\"odinger equations. The model case is $-\Delta u=Vu$
for $u\in W_0^{1,2}(D)$ with $D$ a bounded domain in ${\bf R^n}$. We use the
Sobolev embedding theorem, and in some cases the Moser-Trudinger inequality and
the Hardy-Sobolev inequality, to derive necessary conditions for the existence
of nontrivial solutions. These conditions usually involve a lower bound for a
product of powers of the norm of $V$, the measure of $D$, and a sharp Sobolev
constant. In most cases, these inequalities are best possible.


title: Electric Current Equilibrium in the Corona

abstract:
  A hyperbolic flux-tube configuration containing a null point below the flux
rope is considered as a pre-eruptive state of coronal mass ejections that start
simultaneously with flares. We demonstrate that this configuration is unstable
and cannot exist for a long time in the solar corona. The inference follows
from general equilibrium conditions and from analyzing simple models of the
flux-rope equilibrium. A direct consequence of the stable flux-rope equilibrium
in the corona are separatrices in the horizontal-field distribution in the
chromosphere. They can be recognized as specific "herring-bone structures" in a
chromospheric fibril pattern.


title: Topological Single Electron Pumping Assisted by Majorana Fermions

abstract:
  Single electron pumping based on the topological property of Majorana
fermions (MFs) is proposed. The setup consists of a quantum dot and four nano
topological superconductors (TSs) connected by constriction junctions, with an
additional vortex located in the loop of TSs. Operation is performed by gate
voltages at constriction junctions. Simulations with Bogloliubov-de Gennes
equation demonstrate successfully quantum protection during switching
operation.


title: Geometric Triviality of the Strongly Minimal Second Painlev\'e equations

abstract:
  We show that the strongly minimal second Painlev\'e equation (y" =
2y^3+ty+\alpha) is geometrically trivial, that is we show that if y_1,...,y_n
are distinct solutions such that y_1,y_1',y_2,y_2',...,y_n,y_n' are
algebraically dependent over C(t), then already for some i<j, y_i,y_i',y_j,y_j'
are algebraically dependent over C(t). This gives an extension of some recent
result for the second Painlev\'e equation to the non generic parameters.


title: Diffusivity in multiple scattering systems

abstract:
  We consider random flights of point particles inside $n$-dimensional channels
of the form $\mathbb{R}^{k} \times \mathbb{B}^{n-k}$, where $\mathbb{B}^{n-k}$
is a ball of radius $r$ in dimension $n-k$. The particle velocities immediately
after each collision with the boundary of the channel comprise a Markov chain
with a transition probabilities operator $P$ that is determined by a choice of
(billiard-like) random mechanical model of the particle-surface interaction at
the "microscopic" scale. Our central concern is the relationship between the
scattering properties encoded in $P$ and the constant of diffusivity of a
Brownian motion obtained by an appropriate limit of the random flight in the
channel. Markov operators obtained in this way are {\em natural} (definition
below), which means, in particular, that (1) the (at the surface)
Maxwell-Boltzmann velocity distribution with a given surface temperature, when
the surface model contains moving parts, or (2) the so-called Knudsen cosine
law, when this model is purely geometric, is the stationary distribution of
$P$. We show by a suitable generalization of a central limit theorem of Kipnis
and Varadhan how the diffusivity is expressed in terms of the spectrum of $P$
and compute, in the case of 2-dimensional channels, the exact values of the
diffusivity for a class of parametric microscopic surface models of the above
geometric type (2).


title:
On ponderomotive effects induced by Alfven waves in inhomogeneous 2.5D
  MHD plasmas

abstract:
  Where spatial gradients in the amplitude of an Alfven wave are non-zero, a
nonlinear magnetic-pressure gradient acts upon the medium (the ponderomotive
force). We investigate the nature of such a force in inhomogeneous 2.5D MHD
plasmas by analysing source terms in the nonlinear wave equations for the
general case of inhomogeneous B and {\rho}, and consider supporting nonlinear
numerical simulations. Our equations indicate there are two distinct classes of
ponderomotive effect induced by Alfven waves in general 2.5D MHD, each with
both a longitudinal and transverse manifestation; i) Geometric Effects:
Gradients in the pulse geometry relative to the background magnetic field cause
the wave to sustain cospatial disturbances, the longitudinal and transverse
daughter disturbances - where we report on the transverse disturbance for the
first time. ii) Grad (c_A) Effects: Where a pulse propagates through an
inhomogeneous region (where the non-zero gradients in the Alfven-speed profile
are non-zero), the nonlinear magnetic-pressure gradient acts to accelerate the
plasma. Transverse gradients (phase mixing regions) excite independently
propagating fast magnetoacoustic waves (generalising the result of Nakariakov
et al. 1997, Solar Physics, 175, 93) and longitudinal gradients perturb along
the field (thus creating static disturbances in {\beta} = 0, and slow waves in
{\beta} \= 0).
  We additionally demonstrate that mode conversion due the nonlinear Lorentz
force is a one-way process, and does not act as a mechanism to nonlinearly
generate Alfven waves due to propagating magnetoacoustic waves. We conclude
that these ponderomotive effects are induced by an Alfven wave propagating in
any MHD medium, and have the potential to have significant consequences on the
dynamics of energy transport and aspects of dissipation provided the system is
sufficiently nonlinear and inhomogeneous.


title:
Topological phases of quasi-one-dimensional fermionic atoms with a
  synthetic gauge field

abstract:
  We theoretically investigate the effect of intertube tunneling in topological
superfluid phases of a quasi-one-dimensional Fermi gas with a Rashba-type
spin-orbit interaction. It is shown that the effective Hamiltonian is analogous
to that of a nanowire topological superconductor with multibands. Using a
hidden mirror symmetry in the system, we introduce a new topological number
that ensures the existence of non-Abelian Majorana zero modes even in the
presence of intertube tunneling. It is demonstrated from the full numerical
calculation of self-consistent equations that some of Majorana modes survive
against the intertube tunneling, when the number of one-dimensional tubes is
odd in the $y$-direction. We also discuss a generalization of our consideration
to nanowire topological superconductors.


title:
Variable gamma-ray emission from the Crab Nebula: short flares and long
  "waves"

abstract:
  Gamma-ray emission from the Crab Nebula has been recently shown to be
unsteady. In this paper, we study the flux and spectral variability of the Crab
above 100 MeV on different timescales ranging from days to weeks. In addition
to the four main intense and day-long flares detected by AGILE and Fermi-LAT
between Sept. 2007 and Sept. 2012, we find evidence for week-long and less
intense episodes of enhanced gamma-ray emission that we call "waves".
Statistically significant "waves" show timescales of 1-2 weeks, and can occur
by themselves or in association with shorter flares. We present a refined flux
and spectral analysis of the Sept. - Oct. 2007 gamma-ray enhancement episode
detected by AGILE that shows both "wave" and flaring behavior. We extend our
analysis to the publicly available Fermi-LAT dataset and show that several
additional "wave" episodes can be identified. We discuss the spectral
properties of the September 2007 "wave"/flare event and show that the physical
properties of the "waves" are intermediate between steady and flaring states.
Plasma instabilities inducing "waves" appear to involve spatial distances l
\sim 10^{16} cm and enhanced magnetic fields B \sim (0.5 - 1) mG. Day-long
flares are characterized by smaller distances and larger local magnetic fields.
Typically, the deduced total energy associated with the "wave" phenomenon (E_w
\sim 10^{42} erg, where E_w is the kinetic energy of the emitting particles) is
comparable with that associated to the flares, and can reach a few percent of
the total available pulsar spindown energy. Most likely, flares and waves are
the product of the same class of plasma instabilities that we show acting on
different timescales and radiation intensities.


title: On Translation Invariant Kernels and Screw Functions

abstract:
  We explore the connection between Hilbertian metrics and positive definite
kernels on the real line. In particular, we look at a well-known
characterization of translation invariant Hilbertian metrics on the real line
by von Neumann and Schoenberg (1941). Using this result we are able to give an
alternate proof of Bochner's theorem for translation invariant positive
definite kernels on the real line (Rudin, 1962).


title: The structure of the merging RCS 231953+00 Supercluster at z ~ 0.9

abstract:
  The RCS 2319+00 supercluster is a massive supercluster at z=0.9 comprising
three optically selected, spectroscopically confirmed clusters separated by <3
Mpc on the plane of the sky. This supercluster is one of a few known examples
of the progenitors of present-day massive clusters (10^{15} Msun by z~0.5). We
present an extensive spectroscopic campaign carried out on the supercluster
field resulting, in conjunction with previously published data, in 1961 high
confidence galaxy redshifts. We find 302 structure members spanning three
distinct redshift walls separated from one another by ~65 Mpc. The component
clusters have spectroscopic redshifts of 0.901, 0.905 and 0.905. The velocity
dispersions are consistent with those predicted from X-ray data, giving
estimated cluster masses of ~10^{14.5} - 10^{14.9} Msun. The Dressler-Shectman
test finds evidence of substructure in the supercluster field and a
friends-of-friends analysis identified 5 groups in the supercluster, including
a filamentary structure stretching between two cluster cores previously
identified in the infrared by Coppin et al. (2012). The galaxy colors further
show this filamentary structure to be a unique region of activity within the
supercluster, comprised mainly of blue galaxies compared to the ~43-77%
red-sequence galaxies present in the other groups and cluster cores. Richness
estimates from stacked luminosity function fits results in average group mass
estimates consistent with ~10^{13} Msun halos. Currently, 22% of our confirmed
members reside in >~10^{13} Msun groups/clusters destined to merge onto the
most massive cluster, in agreement with the massive halo galaxy fractions
important in cluster galaxy pre-processing in N-body simulation merger tree
studies.


title: Limits of isotropic universes with interacting fluids

abstract:
  We find various asymptotic limits of universes containing two interacting
fluids which interact and exchange energy. We study the finite-time
singularities that may develop in these cosmologies and obtain the asymptotic
behaviours of the solutions near such blow up regimes.


title: Exclusive diffractive photon bremsstrahlung at the LHC

abstract:
  We calculate differential distributions for the $p p \to p p \gamma$ reaction
at the LHC energy $\sqrt{s} = 14$ TeV. We consider diffractive classical
bremsstrahlung mechanisms including effects of non point-like nature of
protons. In addition, we take into account (vector meson)-pomeron, photon-pion
as well as photon-pomeron exchange processes for the first time in the
literature. Predictions for the total cross section and several observables
related to these processes e.g. differential distributions in pseudorapidities
and transverse momenta of photons or protons are shown and discussed. The
integrated diffractive bremsstrahlung cross section ($E_{\gamma}>100$ GeV) is
only of the order of $\mu$b. We try to identify regions of the phase space
where one of the mechanisms dominates. The classical bremsstrahlung dominates
at large forward/backward photon pseudorapidities, close to the
pseudorapidities of scattered protons. In contrast, the photon-pomeron
(pomeron-photon) mechanism dominates at midrapidities but the related cross
section is rather small. In comparison the virtual-omega rescattering mechanism
contributes at smaller angles of photons (larger photon rapidities). Photons in
the forward/backward region can be measured by the Zero Degree Calorimeters
(ZDCs) installed in experiments at the LHC while the midrapidity photons are
difficult to measure (small cross section, small photon transverse momenta).
Protons could be measured by ALFA detector (ATLAS) or TOTEM detector at CMS.
The exclusivity could be checked with the help of main central detectors.


title: Large Neighborhood Local Search for the Maximum Set Packing Problem

abstract:
  In this paper we consider the classical maximum set packing problem where set
cardinality is upper bounded by $k$. We show how to design a variant of a
polynomial-time local search algorithm with performance guarantee $(k+2)/3$.
This local search algorithm is a special case of a more general procedure that
allows to swap up to $\Theta(\log n)$ elements per iteration. We also design
problem instances with locality gap $k/3$ even for a wide class of exponential
time local search procedures, which can swap up to $cn$ elements for a constant
$c$. This shows that our analysis of this class of algorithms is almost tight.


title: Single top quark measurements with CMS

abstract:
  Measurements of single top quark production are presented, performed using
CMS data collected in 2011 and 2012 at centre-of-mass energies of 7 and 8 TeV.
The cross sections for the electroweak production of single top quarks in the
t-channel and in association with W-bosons is measured and the results are used
to place constraints on the CKM matrix element |V_tb|.


title: Spin currents in non-inertial frames

abstract:
  The covariant Dirac equation and its solutions show that rotation and
acceleration can be used to generate and control spin currents.


title: Generalizations of the Los-Tarski Preservation Theorem

abstract:
  We present new preservation theorems that semantically characterize the
$\exists^k \forall^*$ and $\forall^k \exists^*$ prefix classes of first order
logic, for each natural number $k$. Unlike preservation theorems in the
literature that characterize the $\exists^* \forall^*$ and $\forall^*
\exists^*$ prefix classes, our theorems relate the count of quantifiers in the
leading block of the quantifier prefix to natural quantitative properties of
the models. As special cases of our results, we obtain the classical Los-Tarski
preservation theorem for sentences in both its extensional and substructural
versions. For arbitrary finite vocabularies, we also generalize the extensional
version of the Los-Tarski preservation theorem for theories. We also present an
interpolant-based approach towards these results. Finally, we present partial
results towards generalizing to theories, the substructural version of the
Los-Tarski theorem and in the process, we give a preservation theorem that
provides a semantic characterization of $\Sigma^0_n$ theories for each natural
number $n$.


title: Magnetohydrodynamic waves driven by p-modes

abstract:
  Waves are observed at all layers of the solar atmosphere and the magnetic
field plays a key role in their propagation. While deep down in the atmosphere
the p-modes are almost entirely of acoustic nature, in the upper layers
magnetic forces are dominating, leading to a large variety of new wave modes.
Significant advances have been made recently in our understanding of the
physics of waves interaction with magnetic structures, with the help of
analytical theories, numerical simulations, as well as high-resolution
observations. In this contribution, we review recent observational findings and
current theoretical ideas in the field, with an emphasis on the following
questions: (i) Peculiarities of the observed wave propagation in network, plage
and facular regions; (ii) Role of the mode transformation and observational
evidences of this process; (iii) Coupling of the photosphere, chromosphere, and
above by means of waves propagating in magnetic structures.


title: Local tadpole galaxies: dynamics and metallicity

abstract:
  Tadpole galaxies, with a bright peripheral clump on a faint tail, are
morphological types unusual in the nearby universe but very common early on.
Low mass local tadpoles were identified and studied photometrically in a
previous work, which we complete here analyzing their chemical and dynamical
properties. We measure Halpha velocity curves of seven local tadpoles,
representing 50% of the initial sample. Five of them show evidence for rotation
(sim 70%), and a sixth target hints at it. Often the center of rotation is
spatially offset with respect to the tadpole head (3 out of 5 cases). The size
and velocity dispersion of the heads are typical of giant HII regions, and
three of them yield dynamical masses in fair agreement with their stellar
masses as inferred from photometry. In four cases the velocity dispersion at
the head is reduced with respect to its immediate surroundings. The oxygen
metallicity estimated from [NII]6583/Halpha often shows significant spatial
variations across the galaxies (sim 0.5 dex), being smallest at the head and
larger elsewhere. The resulting chemical abundance gradients are opposite to
the ones observed in local spirals, but agrees with disk galaxies at high
redshift. We interpret the metallicity variation as a sign of external gas
accretion (cold-flows) onto the head of the tadpole. The galaxies are low
metallicity outliers of the mass-metallicity relationship. In particular, two
of the tadpole heads are extremely metal poor, with a metallicity smaller than
a tenth of the solar value. These two targets are also very young (ages smaller
than 5 Myr). All these results combined are consistent with the local tadpole
galaxies being disks in early stages of assembling, with their star formation
sustained by accretion of external metal poor gas.


title: Exact self-similar solutions in Born-Infeld theory

abstract:
  We present a new class of exact self-similar solutions possessing cylindrical
or spherical symmetry in Born-Infeld theory. A cylindrically symmetric solution
describes the propagation of a cylindrical electromagnetic disturbance in a
constant background magnetic field in Born-Infeld electrodynamics. We show that
this solution corresponds to vacuum breakdown and the subsequent propagation of
an electron-positron avalanche. The proposed method of finding exact analytical
solutions can be generalized to the model of a spherically symmetric scalar
Born-Infeld field in the ($n+1$)-dimensional Minkowski space-time. As an
example, the case $n=3$ is discussed.


title:
The s-process in the Galactic halo: the fifth signature of spinstars in
  the early Universe?

abstract:
  Very old halo stars were previously found to show at least four different
abundance 'anomalies', which models of fast rotating massive stars (spinstars)
can successfully account for: rise of N/O and C/O, low 12C/13C and a
primary-like evolution of Be and B. Here we show the impact of these same stars
in the enrichment of Sr and Ba in the early Universe. We study if the s-process
production of fast rotating massive stars can offer an explanation for the
observed spread in [Sr/Ba] ratio in halo stars with metallicity [Fe/H]< -2.5.
By means of a chemical inhomogeneous model we compute the enrichment of Sr and
Ba by massive stars in the Galactic halo. Our model takes into account, for the
first time, the contribution of spinstars. Our model (combining an r-process
contribution with a s-process from fast rotating massive stars) is able to
reproduce for the first time the observed scatter in the [Sr/Ba] ratio at
[Fe/H]< -2.5. Toward higher metallicities, the stochasticity of the star
formation fades away due to the increasing number of exploding and enriching
stars, and as a consequence the predicted scatter decreases. Our scenario is
again based on the existence of spinstars in the early Universe. Very old halo
stars were previously found to show at least four other abundance 'anomalies',
which rotating models of massive stars can successfully account for. Our
results provide a 5th independent signature of the existence of fast rotating
massive stars: an early enrichment of the Universe in s-process elements.


title:
Computational Complexity of Inexact Gradient Augmented Lagrangian
  Methods: Application to Constrained MPC

abstract:
  We study the computational complexity certification of inexact gradient
augmented Lagrangian methods for solving convex optimization problems with
complicated constraints. We solve the augmented Lagrangian dual problem that
arises from the relaxation of complicating constraints with gradient and fast
gradient methods based on inexact first order information. Moreover, since the
exact solution of the augmented Lagrangian primal problem is hard to compute in
practice, we solve this problem up to some given inner accuracy. We derive
relations between the inner and the outer accuracy of the primal and dual
problems and we give a full convergence rate analysis for both gradient and
fast gradient algorithms. We provide estimates on the primal and dual
suboptimality and on primal feasibility violation of the generated approximate
primal and dual solutions. Our analysis relies on the Lipschitz property of the
dual function and on inexact dual gradients. We also discuss implementation
aspects of the proposed algorithms on constrained model predictive control
problems for embedded linear systems.


title:
Partial dynamical symmetry as a selection criterion for many-body
  interactions

abstract:
  We propose the use of partial dynamical symmetry (PDS) as a selection
criterion for higher-order terms in situations when a prescribed symmetry is
obeyed by some states and is strongly broken in others. The procedure is
demonstrated in a first systematic classification of many-body interactions
with SU(3) PDS that can improve the description of deformed nuclei. As an
example, the triaxial features of the nucleus 156Gd are analyzed.


title: Vortices in Ionization Collisions by Positron Impact

abstract:
  The presence of vortices in the ionisation of hydrogen atoms by positrons at
intermediate impact energies is investigated. The present findings show that a
previously reported minima in the fully-differential cross section is the
signature of a vortex in the continuum positron-electron-proton system. The
behaviour of the real and imaginary parts of the complex-valued transition
matrix is studied in order to determine and characterize the vortex in momentum
space. The obtained information is translated to fully-differential ionisation
cross sections, feasible of being measured with currently available techniques.


title:
Non-direct limit of simple dimension groups with finitely many pure
  traces

abstract:
  There exist simple dimension groups which cannot be expressed as a direct
limit of simple, or even approximately divisible dimension groups, each with
finitely many pure traces, and we can specify its infinite-dimensional Choquet
simplex of traces; a more drastic property is noted. On the other hand, a very
easy argument shows that if $G$ is a $p$-divisible simple dimension group (for
some integer $p>1$), then it can be expressed as such a direct limit. We also
enlarge the class of initial objects for AF (and slightly more general)
C*-algebras.


title: Weak abelian periodicity of infinite words

abstract:
  We say that an infinite word w is weak abelian periodic if it can be
factorized into finite words with the same frequencies of letters. In the paper
we study properties of weak abelian periodicity, its relations with balance and
frequency. We establish necessary and sufficient conditions for weak abelian
periodicity of fixed points of uniform binary morphisms. Also, we discuss weak
abelian periodicity in minimal subshifts.


title: On positive embeddings of C(K) spaces

abstract:
  We investigate isomorphic embeddings $T: C(K)\to C(L)$ between Banach spaces
of continuous functions. We show that if such an embedding $T$ is a positive
operator then $K$ is an image of $L$ under a upper semicontinuous set-function
having finite values. Moreover we show that $K$ has a $\pi$-base of sets which
closures a continuous images of compact subspaces of $L$. Our results imply in
particular that if $C(K)$ can be positively embedded into $C(L)$ then some
topological properties of $L$, such as countable tightness of Frechetness, pass
to the space $K$. We show that some arbitrary isomorphic embeddings $C(K)\to
C(L)$ can be, in a sense, reduced to positive embeddings.


abstract:
  In this paper we determine a minimal set of generators for the Cox rings of
extremal rational elliptic surfaces. Moreover, we develop a technique for
computing the ideal of relations between them which allows, in all but three
cases, to provide a presentation of the Cox ring.


title:
Dynamical correction to linear Kohn-Sham conductances from static
  density functional theory

abstract:
  For molecules weakly coupled to leads the exact linear Kohn-Sham (KS)
conductance can be orders of magnitude larger than the true linear conductance
due to the lack of dynamical exchange-correlation (xc) corrections. In this
work we show how to incorporate dynamical effects in KS transport calculations.
The only quantity needed is the static xc potential in the molecular junction.
Our scheme provides a comprehensive description of Coulomb blockade without
breaking the spin symmetry. This is explicitly demonstrated in single-wall
nanotubes where the corrected conductance is in good agreement with
experimental data whereas the KS conductance fails dramatically.


title:
Calibration of the total infrared luminosity of nearby galaxies from
  Spitzer and Herschel bands

abstract:
  We present new empirical calibrations to estimate resolved and integrated
total infrared luminosities from Spitzer and Herschel bands used as
monochromatic or combined tracers. We base our calibrations on resolved
elements of nearby galaxies (3 to 30 Mpc) observed with Herschel. We perform a
resolved SED modelling of these objects using the Draine and Li (2007) dust
models and investigate the influence of the addition of SPIRE measurements in
the estimation of LTIR. We find that using data up to 250 um leads to local
LTIR values consistent with those obtained with a complete coverage (up to 500
um) within 10 per cent for most of our resolved elements. We then study the
distribution of energy in the resolved SEDs of our galaxies. The bulk of energy
(30-50 per cent) is contained in the (70-160 um) band. The (24-70 um) fraction
decreases with increasing metallicity. The (160-1100 um) submillimeter band can
account for up to 25 per cent of the LTIR in metal-rich galaxies. We
investigate the correlation between TIR surface brightnesses/luminosities and
monochromatic Spitzer and Herschel surface brightnesses/luminosities. The three
PACS bands can be used as reliable monochromatic estimators of the LTIR, the
100 um band being the most reliable monochromatic tracer. There is also a
strong correlation between the SPIRE 250um and LTIR, although with more scatter
than for the PACS relations. We also study the ability of our monochromatic
relations to reproduce integrated LTIR of nearby galaxies as well as LTIR of
z=1-3 sources. Finally, we provide calibration coefficients that can be used to
derive TIR surface brightnesses/luminosities from a combination of Spitzer and
Herschel surface brightnesses/fluxes and analyse the associated uncertainties.


title:
A Dynamical Cross-over Regime in the Transmission and Reflection Spectra
  of Evanescent Waves with 2D Arrays of Josephson Junctions

abstract:
  A dynamical cross-over regime is revealed when exposing a classical
two-dimensional ordered Josephson junction (JJ) array to evanescent waves and
tuning the incident microwave power. At the lowest possible temperature for
these experiments, 1.1 K, and at the lowest power setting, -55 dBm, evanescent
waves are transmitted without loss and the resonance exhibits a quality factor
of ~ 4200. A second, smaller resonance, which evolves with increasing power
from the main resonance, is also investigated. In contrast to the behavior of
the main resonance, this second peak grows as the incident power is increased
and does not maintain a fixed resonant frequency for temperatures less than the
superconducting critical temperature of niobium. The tunability of both
resonances is studied as a function of temperature and microwave power. Finally
we speculate that this dynamical crossover regime is evidence of a transition
between two states of phase coherence where at low microwave power the JJ
arrays are phase locked and at high microwave power the JJ arrays are unlocked.


title: The Spin State and Spectroscopic Modes of Multiferroic BiFeO3

abstract:
  Spectroscopic modes provide the most sensitive probe of the very weak
interactions responsible for the properties of the long-wavelength cycloid in
the multiferroic phase of \BF below $\TN \approx 640$ K. Three of the four
modes measured by THz and Raman spectroscopies were recently identified using a
simple microscopic model. While a Dzyaloshinskii-Moriya (DM) interaction $D$
along $[-1,2,-1]$ induces the cycloid with wavevector $(2\pi /a)(0.5+\delta,
0.5, 0.5-\delta)$ ($\delta \approx 0.0045$), easy-axis anisotropy $K$ along the
$[1,1,1]$ direction of the electric polarization ${\bf P}$ induces higher
harmonics of the cycloid, which split the $\Psi_1$ modes at 2.49 and 2.67 meV
and activate the $\Phi_2$ mode at 3.38 meV. However, that model could not
explain the observed low-frequency mode at about 2.17 meV. We now demonstrate
that an additional DM interaction $D'$ along $[1,1,1]$ not only produces the
observed weak ferromagnetic moment of the high-field phase above 18 T but also
activates the spectroscopic matrix elements of the nearly-degenerate,
low-frequency $\Psi_0$ and $\Phi_1$ modes, although their scattering
intensities remain extremely weak. Even in the absence of easy-axis anisotropy,
$D'$ produces cycloidal harmonics that split $\Psi_1 $ and activate $\Phi_2$.
However, the observed mode frequencies and selection rules require that both
$D'$ and $K$ are nonzero. This work also resolves an earlier disagreement
between spectroscopic and inelastic neutron-scattering measurements.


title: Exact sum rules for inhomogeneous strings

abstract:
  We derive explicit expressions for the sum rules of the eigenvalues of
inhomogeneous strings with arbitrary density and with different boundary
conditions. We show that the sum rule of order $N$ may be obtained in terms of
a diagrammatic expansion, with $(N-1)!/2$ independent diagrams. These sum rules
are used to derive upper and lower bounds to the energy of the fundamental mode
of an inhomogeneous string; we also show that it is possible to improve these
approximations taking into account the asymptotic behaviour of the spectrum and
applying the Shanks transformation to the sequence of approximations obtained
to the different orders. We discuss three applications of these results.


title: Hidden Ghost in Massive gravity

abstract:
  The Hessian's determinant for a version of massive gravity given by an
infinite expansion of a square root function of the induced metric, vanishes.
We show that it allows us to eliminate one of four scalar fields used to
generate the graviton mass. This, however, gives rise to the appearance of
extra terms in the action with the squared time derivative of the metric, thus
signaling that a nonlinear ghost survives.We demonstrate this phenomenon
considering a simple system with constraint, which is supposed to reduces the
number of physical degrees of freedom, however, we explicitly show how the
constraint forces the metric to propagate an extra tachyonic state.


title: Magnetorotational instability in relativistic hypermassive neutron stars

abstract:
  A differentially rotating hypermassive neutron star (HMNS) is a metastable
object which can be formed in the merger of neutron-star binaries. The eventual
collapse of the HMNS into a black hole is a key element in generating the
physical conditions expected to accompany the launch of a short gamma-ray
burst. We investigate the influence of magnetic fields on HMNSs by performing
three-dimensional simulations in general-relativistic magnetohydrodynamics. In
particular, we provide direct evidence for the occurrence of the
magnetorotational instability (MRI) in HMNS interiors. For the first time in
simulations of these systems, rapidly-growing and spatially-periodic structures
are observed to form with features like those of the channel flows produced by
the MRI in other systems. Moreover, the growth time and wavelength of the
fastest-growing mode are extracted and compared successfully with analytical
predictions. The MRI emerges as an important mechanism to amplify magnetic
fields over the lifetime of the HMNS, whose collapse to a black hole is
accelerated. The evidence provided here that the MRI can actually develop in
HMNSs could have a profound impact on the outcome of the merger of neutron-star
binaries and on its connection to short gamma-ray bursts.


title:
Formation of photon spheres in boson stars with a nonminimally coupled
  field

abstract:
  A static, spherically symmetric, asymptotically flat spacetime may allow for
circular, closed null-geodesics which are said to belong to a photon sphere. In
the context of gravitational lensing in the strong deflection regime, the
presence of a photon sphere leads to an unbounded angle of deflection of light
(multiple turns) and formation of relativistic images. In this paper, we show
that photon spheres may form in some configurations of boson stars constructed
with a free massive complex scalar field nonminimally coupled to gravity.
Assuming that the boson star is transparent to light, photon spheres would give
raise not only to phenomena in the realm of strong gravitational lensing, but
also to considerably increased photon flux in the central region of the star,
relative to the flux in its surroundings.


title: Tight spans, Isbell completions and semi-tropical modules

abstract:
  In this paper we consider the categorical Isbell completion construction for
generalized metric spaces in the sense of Lawvere. We show that this is an
analogue of the tight span construction of classical metric spaces, and that
the Isbell completion coincides with the directed tight span of Hirai and
Koichi. The notions of categorical completion and cocompletion are related to
the existence of semi-tropical module structure, and it is shown that the
Isbell completion (hence the directed tight span) has two different
semi-tropical module structures.


title: Exact sum rules for inhomogeneous drums

abstract:
  We derive general expressions for the sum rules of the eigenvalues of drums
of arbitrary shape and arbitrary density, obeying different boundary
conditions. The formulas that we present are a generalization of the analogous
formulas for one dimensional inhomogeneous systems that we have obtained in a
previous paper. We also discuss the extension of these formulas to higher
dimensions. We show that in the special case of a density depending only on one
variable the sum rules of any integer order can be expressed in terms of a
single series. As an application of our result we derive exact sum rules for
the a homogeneous circular annulus with different boundary conditions, for a
homogeneous circular sector and for a radially inhomogeneous circular annulus
with Dirichlet boundary conditions.


title: Planar Symmetry in f(T) gravity

abstract:
  Exact solutions for planar Weitzenboch geometries in generalized teleparallel
gravity with torsion is presented. The model predicted the existence of Moller,
Kattler-Wittaker and planar de-Sitter geometries for different forms of action.


title: Homotopic Group ICA for Multi-Subject Brain Imaging Data

abstract:
  Independent Component Analysis (ICA) is a computational technique for
revealing latent factors that underlie sets of measurements or signals. It has
become a standard technique in functional neuroimaging. In functional
neuroimaging, so called group ICA (gICA) seeks to identify and quantify
networks of correlated regions across subjects. This paper reports on the
development of a new group ICA approach, Homotopic Group ICA (H-gICA), for
blind source separation of resting state functional magnetic resonance imaging
(fMRI) data. Resting state brain functional homotopy is the similarity of
spontaneous fluctuations between bilaterally symmetrically opposing regions
(i.e. those symmetric with respect to the mid-sagittal plane) (Zuo et al.,
2010). The approach we proposed improves network estimates by leveraging this
known brain functional homotopy. H-gICA increases the potential for network
discovery, effectively by averaging information across hemispheres. It is
theoretically proven to be identical to standard group ICA when the true
sources are both perfectly homotopic and noise-free, while simulation studies
and data explorations demonstrate its benefits in the presence of noise.
Moreover, compared to commonly applied group ICA algorithms, the structure of
the H-gICA input data leads to significant improvement in computational
efficiency. A simulation study comfirms its effectiveness in homotopic,
non-homotopic and mixed settings, as well as on the landmark ADHD-200 dataset.
From a relatively small subset of data, several brain networks were found
including: the visual, the default mode and auditory networks, as well as
others. These were shown to be more contiguous and clearly delineated than the
corresponding ordinary group ICA. Finally, in addition to improving network
estimation, H-gICA facilitates the investigation of functional homotopy via
ICA-based networks.


title: Particle Acceleration by Magnetic Reconnection

abstract:
  Observational data require a rich variety of mechanisms to accelerate fast
particles in astrophysical environments operating under different conditions.
The mechanisms discussed in the literature include varying magnetic fields in
compact sources, stochastic processes in turbulent environments, and
acceleration behind shocks. An alternative, much less explored mechanism
involves particle acceleration within magnetic reconnection sites. In this
chapter we discuss this mechanism and show that particles can be efficiently
accelerated by reconnection through a first order Fermi process within large
scale current sheets (specially when in the presence of local turbulence which
speeds up the reconnection and make the acceleration region thicker) and also
through a second order Fermi process in pure MHD turbulent environments.


title:
Evidence for multiple populations in the massive globular cluster NGC
  2419 from deep uVI LBT photometry

abstract:
  We present accurate wide-field uVI photometry of the remote and massive
Galactic globular cluster NGC 2419, aimed at searching for the u-V color spread
along the Red Giant Branch (RGB) that is generally interpreted as the
photometric signature of the presence of multiple populations in globular
clusters. Focusing on the RGB stars in the magnitude range 19.8<V<22.0, we find
that (a) the u-V, u-I and the V-I spreads about the RGB ridge line are
significantly larger than that expected from observational errors, accurately
quantified by means of extensive artificial stars experiments, (b) the
intrinsic color spread in u-V and u-I are larger than in V-I, (c) the stars
lying to the blue of the RGB ridge line in u-V and u-I are significantly more
concentrated toward the cluster center than those lying to the red of that
line. All the above observational facts can be interpreted in a scenario where
a sizable fraction of cluster stars belong to a second generation heavily
enriched in Helium. Finally we find that bright RGB stars (17.5<V<19.0) having
[Mg/Fe]<0.0 lie preferentially on the red side of the cluster RGB, while those
having [Mg/Fe]>0.0 lie preferentially on the blue side.


title: Infinite Body Centered Cubic Network of Identical Resistors

abstract:
  We express the equivalent resistance between the origin and any other lattice
site in an infinite Body Centered Cubic (BCC) network consisting of identical
resistors each of resistance R rationally in terms of known values and . The
equivalent resistance is then calculated. Finally, for large separation between
the origin and the lattice site two asymptotic formulas for the resistance are
presented and some numerical results with analysis are given.


title: Transfinite game values in infinite chess

abstract:
  We investigate the transfinite game values arising in infinite chess,
providing both upper and lower bounds on the supremum of these values---the
omega one of chess---with two senses depending on whether one considers only
finite positions or also positions with infinitely many pieces. For lower
bounds, we present specific infinite positions with transfinite game values of
omega, omega^2, omega^2 times k, and omega^3. By embedding trees into chess, we
show that there is a computable infinite chess position that is a win for white
if the players are required to play according to a deterministic computable
strategy, but which is a draw without that restriction. Finally, we prove that
every countable ordinal arises as the game value of a position in infinite
three-dimensional chess, and consequently the omega one of infinite
three-dimensional chess is as large as it can be, namely, true omega one.


title: Graph and Network Theory in Physics

abstract:
  A book Chapter consisting of some of the main areas of research in graph
theory applied to physics. It includes graphs in condensed matter theory, such
as the tight-binding and the Hubbard model. It follows the study of graph
theory and statistical physics by means of the analysis of the Potts model.
Then, we consider the use of graph polynomials in solving Feynman integrals,
graphs and electrical networks, vibrational analysis in networked systems and
random graphs. The second part deals with the study of complex networks and
includes the models of "small-world", "scale-freeness", network motifs,
centrality measures, the use of statistical mechanics for the analysis of
networks and network communicability and the study of communities in networks.
The chapter is finished by considering some dynamical models on networks, such
as the consensus analysis, synchronization of coupled oscillators and epidemic
models on networks.


title: Soft triple-real radiation for Higgs production at N3LO

abstract:
  We present the two first terms in the threshold expansion of Higgs production
partonic cross-sections at hadron colliders for processes with three partons in
the final state. These are contributions to the inclusive Higgs cross-section
in gluon fusion at N3LO. We have developed a new technique for the expansion of
the squared matrix-elements around the soft limit and for the reduction of the
required phase-space integrals to only ten single-scale master integrals. We
compute the master integrals building upon modern techniques for the
integration of multidimensional integrals in dimensional regularization. Our
results constitute an important step towards a systematic computation of the
Higgs boson cross-section as an expansion around the threshold limit.


title:
Professor "Nonlinear": Obituary and memoir for Roman Juszkiewicz
  (1952-2012)

abstract:
  On 28th and 29th of January 2013 we held an international meeting in Zielona
G\'ora (Poland) honouring the first anniversary of premature passing away^(1)
of Professor Roman Juszkiewicz. We have celebrated an opening of a new seminar
room at the University of Zielona G\'ora commemorated to the memory of Roman
Juszkiewicz and we have shared our anecdotes and memories of this great
scientist and friend. Here we want to present a limited and short memoir and
obituary for Roman Juszkiewicz.
  1: Roman Juszkiewicz passed away on 28th of January 2012


title: Reasoning about Independence in Probabilistic Models of Relational Data

abstract:
  We extend the theory of d-separation to cases in which data instances are not
independent and identically distributed. We show that applying the rules of
d-separation directly to the structure of probabilistic models of relational
data inaccurately infers conditional independence. We introduce relational
d-separation, a theory for deriving conditional independence facts from
relational models. We provide a new representation, the abstract ground graph,
that enables a sound, complete, and computationally efficient method for
answering d-separation queries about relational models, and we present
empirical results that demonstrate effectiveness.


title:
Finite element computation of elliptical vocal tract impedances using
  the two-microphone transfer function method

abstract:
  The experimental two-microphone transfer function method (TMTF) is adapted to
the numerical framework to compute the radiation and input impedances of
three-dimensional vocal tracts of elliptical cross section. In its simplest
version, the TMTF method only requires measuring the acoustic pressure at two
points in an impedance duct and the postprocessing of the corresponding
transfer function. However, some considerations are to be taken into account
when using the TMTF method in the numerical context, which constitute the main
objective of this paper. In particular, the importance of including absorption
at the impedance duct walls to avoid lengthy numerical simulations is discussed
and analytical complex axial wave numbers for elliptical ducts are derived for
this purpose. It is also shown how the plane wave restriction of the TMTF
method can be circumvented to some extent by appropriate location of the
virtual microphones, thus extending the method frequency range of validity.
Virtual microphone spacing is also discussed on the basis of the so called
singularity factor. Numerical examples include the computation of the radiation
impedance of vowels /a/, /i/ and /u/ and the input impedance of vowel /a/, for
simplified vocal tracts of circular and elliptical cross sections.


title: Explaining Zipf's Law via Mental Lexicon

abstract:
  The Zipf's law is the major regularity of statistical linguistics that served
as a prototype for rank-frequency relations and scaling laws in natural
sciences. Here we show that the Zipf's law -- together with its applicability
for a single text and its generalizations to high and low frequencies including
hapax legomena -- can be derived from assuming that the words are drawn into
the text with random probabilities. Their apriori density relates, via the
Bayesian statistics, to general features of the mental lexicon of the author
who produced the text.


title:
Citation impacts revisited: how novel impact measures reflect
  interdisciplinarity and structural change at the local and global level

abstract:
  Citation networks have fed numerous works in scientific evaluation, science
mapping (and more recently large-scale network studies) for decades. The
variety of citation behavior across scientific fields is both a research topic
in sociology of science, and a problem in scientific evaluation. Normalization,
tantamount to a particular weighting of links in the citation network, is
necessary for allowing across-field comparisons of citation scores and
interdisciplinary studies. In addition to classical normalization which
drastically reduces all variability factors altogether, two tracks of research
have emerged in the recent years. One is the revival of iterative "influence
measures". The second is the "citing-side" normalization, whose only purpose is
to control for the main factor of variability, the inequality in citing
propensity, letting other aspects play: knowledge export/imports and growth.
When all variables are defined at the same field-level, two propositions are
established: (a) the gross impact measure identifies with the product of
relative growth rate, gross balance of citation exchanges, and relative number
of references (b) the normalized impact identifies with the product of relative
growth rate and normalized balance. At the science level, the variance of
growth rate over domains is a proxy for change in the system, and the variance
of balance a measure of inter-disciplinary dependences. This opens a new
perspective, where the resulting variance of normalized impact, and a related
measure, the sum of these variances proposed as a Change-Exchange Indicator,
summarize important aspects of science structure and dynamism. Results based on
a decade's data are discussed. The behavior of normalized impact according to
scale changes is also briefly discussed.


title:
Robust Near-Separable Nonnegative Matrix Factorization Using Linear
  Optimization

abstract:
  Nonnegative matrix factorization (NMF) has been shown recently to be
tractable under the separability assumption, under which all the columns of the
input data matrix belong to the convex cone generated by only a few of these
columns. Bittorf, Recht, R\'e and Tropp (`Factoring nonnegative matrices with
linear programs', NIPS 2012) proposed a linear programming (LP) model, referred
to as Hottopixx, which is robust under any small perturbation of the input
matrix. However, Hottopixx has two important drawbacks: (i) the input matrix
has to be normalized, and (ii) the factorization rank has to be known in
advance. In this paper, we generalize Hottopixx in order to resolve these two
drawbacks, that is, we propose a new LP model which does not require
normalization and detects the factorization rank automatically. Moreover, the
new LP model is more flexible, significantly more tolerant to noise, and can
easily be adapted to handle outliers and other noise models. Finally, we show
on several synthetic datasets that it outperforms Hottopixx while competing
favorably with two state-of-the-art methods.


title: Melons are branched polymers

abstract:
  Melonic graphs constitute the family of graphs arising at leading order in
the 1/N expansion of tensor models. They were shown to lead to a continuum
phase, reminiscent of branched polymers. We show here that they are in fact
precisely branched polymers, that is, they possess Hausdorff dimension 2 and
spectral dimension 4/3.


title: Online Learning with Switching Costs and Other Adaptive Adversaries

abstract:
  We study the power of different types of adaptive (nonoblivious) adversaries
in the setting of prediction with expert advice, under both full-information
and bandit feedback. We measure the player's performance using a new notion of
regret, also known as policy regret, which better captures the adversary's
adaptiveness to the player's behavior. In a setting where losses are allowed to
drift, we characterize ---in a nearly complete manner--- the power of adaptive
adversaries with bounded memories and switching costs. In particular, we show
that with switching costs, the attainable rate with bandit feedback is
$\widetilde{\Theta}(T^{2/3})$. Interestingly, this rate is significantly worse
than the $\Theta(\sqrt{T})$ rate attainable with switching costs in the
full-information case. Via a novel reduction from experts to bandits, we also
show that a bounded memory adversary can force $\widetilde{\Theta}(T^{2/3})$
regret even in the full information case, proving that switching costs are
easier to control than bounded memory adversaries. Our lower bounds rely on a
new stochastic adversary strategy that generates loss processes with strong
dependencies.


title: On the geometry of the Batalin-Vilkovisky Laplacian

abstract:
  We define a jet-space analog of the BV-Laplacian, avoiding delta-functions
and infinite constants; instead we show that the main properties of the
BV-Laplacian and its relation to the Schouten bracket originate from the
underlying jet-space geometry.


title: Maxout Networks

abstract:
  We consider the problem of designing models to leverage a recently introduced
approximate model averaging technique called dropout. We define a simple new
model called maxout (so named because its output is the max of a set of inputs,
and because it is a natural companion to dropout) designed to both facilitate
optimization by dropout and improve the accuracy of dropout's fast approximate
model averaging technique. We empirically verify that the model successfully
accomplishes both of these tasks. We use maxout and dropout to demonstrate
state of the art classification performance on four benchmark datasets: MNIST,
CIFAR-10, CIFAR-100, and SVHN.


title: Bivariate gamma-geometric law and its induced L\'evy process

abstract:
  In this article we introduce a three-parameter extension of the bivariate
exponential-geometric (BEG) law (Kozubowski and Panorska, 2005). We refer to
this new distribution as bivariate gamma-geometric (BGG) law. A bivariate
random vector $(X,N)$ follows BGG law if $N$ has geometric distribution and $X$
may be represented (in law) as a sum of $N$ independent and identically
distributed gamma variables, where these variables are independent of $N$.
Statistical properties such as moment generation and characteristic functions,
moments and variance-covariance matrix are provided. The marginal and
conditional laws are also studied. We show that BBG distribution is infinitely
divisible, just as BEG model is. Further, we provide alternative
representations for the BGG distribution and show that it enjoys a geometric
stability property. Maximum likelihood estimation and inference are discussed
and a reparametrization is proposed in order to obtain orthogonality of the
parameters. We present an application to the real data set where our model
provides a better fit than BEG model. Our bivariate distribution induces a
bivariate L\'evy process with correlated gamma and negative binomial processes,
which extends the bivariate L\'evy motion proposed by Kozubowski et al. (2008).
The marginals of our L\'evy motion are mixture of gamma and negative binomial
processes and we named it ${BMixGNB}$ motion. Basic properties such as
stochastic self-similarity and covariance matrix of the process are presented.
The bivariate distribution at fixed time of our ${BMixGNB}$ process is also
studied and some results are derived, including a discussion about maximum
likelihood estimation and inference.


title: Constructing a genome assembly that has the maximum likelihood

abstract:
  We formulate genome assembly problem as an optimization problem in which the
objective function is the likelihood of the assembly given the reads.


title: Comment on "Cooling by Heating: Refrigerator Powered by Photons"

abstract:
  Results obtained recently in Phys. Rev. Lett. 108, 120603 (2012) by Cleuren
et al. apparently contradict to the third law of thermodynamics. We discuss a
scenario for resolving this contradiction, and show that this scenario is
pertinent for clarifying the general message of the third law.


title:
Improved luminosity determination in pp collisions at sqrt(s) = 7 TeV
  using the ATLAS detector at the LHC

abstract:
  The luminosity calibration for the ATLAS detector at the LHC during pp
collisions at sqrt(s) = 7 TeV in 2010 and 2011 is presented. Evaluation of the
luminosity scale is performed using several luminosity-sensitive detectors, and
comparisons are made of the long-term stability and accuracy of this
calibration applied to the pp collisions at sqrt(s) = 7 TeV. A luminosity
uncertainty of Delta L/L = +/- 3.5% is obtained for the 47 pb-1 of data
delivered to ATLAS in 2010, and an uncertainty of Delta L/L = +/- 1.8% is
obtained for the 5.5 fb-1 delivered in 2011.


title: SUSY into Darkness: Heavy Scalars in the CMSSM

abstract:
  A survey of the mSUGRA/CMSSM parameter space is presented. The viable regions
of the parameter space which satisfy all experimental constraints are
identified and discussed. These constraints include a 124-127 GeV mass for the
lightest CP-even Higgs and the correct relic density for cold dark matter
(CDM). The superpartner spectra corresponding to these regions fall within the
well-known hyperbolic branch (HB) and are found to possess sub-TeV neutralinos
and charginos, with mixed Bino/Higgsino LSP's with 200-800 GeV masses. In
addition, the models possess ~3-4 TeV gluino masses and heavy squarks and
sleptons with masses heavier than the gluino mass. Spectra with a Higgs mass
near 125 GeV and a relic density 0.109 < \Omega h^2 < 0.123 are found to
require EWFT at around the one-percent level, while those spectra with a much
lower relic density require EWFT of only a few percent. Moreover, the SI
neutralino-proton direct detection cross-sections are found to be below or
within the XENON100 2-sigma limits and should be experimentally accessible now
or in the near future. Finally, it is pointed-out that the supersymmetry
breaking soft terms corresponding to these regions of the mSUGRA/CMSSM
parameter space (m_0 proportional to m_{1/2} with m_0^2 >> m_{1/2}^2 and A_0 =
-m_{1/2}) may be obtained from general flux-induced soft terms in Type IIB flux
compactifications with D3 branes.


title: Quarkonium formation time in quark-gluon plasma

abstract:
  The quarkonium formation time in a quark-gluon plasma (QGP) is determined
from the space-time correlator of heavy quark vector currents using the
quarkonium in-medium mass and wave function obtained from heavy quark
potentials extracted from the lattice QCD. It is found that the formation time
of a quarkonium increases with the temperature of the QGP and diverges near its
dissociation temperature. Also, the quarkonium formation time is longer if the
heavy quark potential is taken to be the free energy from lattice calculations
for a heavy quark pair, compared to that based on the more negative internal
energy.


title: On the Determination of a Function from an Elliptical Radon Transform

abstract:
  In recent years, Radon type transforms that integrate functions over various
sets of ellipses/ellipsoids have been considered in SAR, ultrasound reflection
tomography, and radio tomography. In this paper, we consider the transform that
integrates a given function in $\RR^n$ over a set of solid ellipsoids of
rotation with a fixed eccentricity and foci restricted to a hyperplane.
Inversion formulas are obtained for appropriate classes of functions that are
even with respect to the hyperplane. Stability estimates, range description,
and local uniqueness results are also provided.


title:
Interface reconstruction in superconducting CaCuO2/SrTiO3 superlattices:
  A hard x-ray photoelectron spectroscopy study

abstract:
  Here we report about the interface reconstruction in the recently discovered
superconducting artificial superlattices based on insulating CaCuO2 and SrTiO3
blocks. Hard x-ray photoelectron spectroscopy shows that the valence bands
alignment prevents any electronic reconstruction by direct charge transfer
between the two blocks. We demonstrate that the electrostatic built-in
potential is suppressed by oxygen redistribution in the alkaline earth
interface planes. By using highly oxidizing growth conditions, the oxygen
coordination in the reconstructed interfaces may be increased, resulting in the
hole doping of the cuprate block and thus in the appearance of
superconductivity.


title:
Ferromagnetic planar Josephson junction with transparent interfaces: a
  {\phi} junction proposal

abstract:
  We calculate the current phase relation of a planar Josephson junction with a
ferromagnetic weak link located on top of a thin normal metal film. Following
experimental observations we assume transparent superconductor-ferromagnet
interfaces. This provides the best interlayer coupling and a low suppression of
the superconducting correlations penetrating from the superconducting
electrodes into the ferromagnetic layer. We show that this Josephson junction
is a promising candidate for an experimental {\phi} junction realization.


title:
Temperature controlled L\'evy flights of minority carriers in
  photoexcited bulk n-InP

abstract:
  We study the spatial distribution of minority carriers arising from their
anomalous photon-assisted diffusion upon photo-excitation at an edge of n-InP
slab for temperatures ranging from 300 K to 78 K. The experiment provides a
realization of the "L\'evy flight" random walk of holes, in which the L\'evy
distribution index gamma is controlled by the temperature. We show that the
variation \gamma(T) is close to that predicted earlier on the basis of the
assumed quasi-equilibrium (van Roosbroek-Shockley) intrinsic emission spectrum,
\gamma=1-\Delta /kT, where \Delta(T) is the Urbach tailing parameter of the
absorption spectra. The decreasing \gamma at lower temperatures results in a
giant enhancement in the spread of holes -- over distances exceeding 1 cm from
the region of photo-excitation.


title:
Quasi-Parallel Segments and Characterization of Unique Bichromatic
  Matchings

abstract:
  Given n red and n blue points in general position in the plane, it is
well-known that there is a perfect matching formed by non-crossing line
segments. We characterize the bichromatic point sets which admit exactly one
non-crossing matching. We give several geometric descriptions of such sets, and
find an O(nlogn) algorithm that checks whether a given bichromatic set has this
property.


title: f-vectors implying vertex decomposability

abstract:
  We prove that if a pure simplicial complex of dimension d with n facets has
the least possible number of (d-1)-dimensional faces among all complexes with n
faces of dimension d, then it is vertex decomposable. This answers a question
of J. Herzog and T. Hibi. In fact we prove a generalization of their theorem
using combinatorial methods.


title: Metrization and Simulation of Controlled Hybrid Systems

abstract:
  The study of controlled hybrid systems requires practical tools for
approximation and comparison of system behaviors. Existing approaches to these
problems impose undue restrictions on the system's continuous and discrete
dynamics. Metrization and simulation of controlled hybrid systems is considered
here in a unified framework by constructing a state space metric. The metric is
applied to develop a numerical simulation algorithm that converges uniformly,
with a known rate of convergence, to orbitally stable executions of controlled
hybrid systems, up to and including Zeno events. Benchmark hybrid phenomena
illustrate the utility of the proposed tools.


title:
Search for WH production with a light Higgs boson decaying to prompt
  electron-jets in proton-proton collisions at sqrt(s)=7 TeV with the ATLAS
  detector

abstract:
  A search is performed for WH production with a light Higgs boson decaying to
hidden-sector particles resulting in clusters of collimated electrons, known as
electron-jets. The search is performed with 2.04 fb-1 of data collected in 2011
with the ATLAS detector at the LHC in proton-proton collisions at sqrt(s)=7
TeV. One event satisfying the signal selection criteria is observed, which is
consistent with the expected background rate. Limits on the product of the WH
production cross section and the branching ratio of a Higgs boson decaying to
prompt electron-jets are calculated as a function of a Higgs boson mass in the
range from 100 GeV to 140 GeV.


title: Analysis of Forensic DNA Mixtures with Artefacts

abstract:
  DNA is now routinely used in criminal investigations and court cases,
although DNA samples taken at crime scenes are of varying quality and therefore
present challenging problems for their interpretation. We present a statistical
model for the quantitative peak information obtained from an electropherogram
(EPG) of a forensic DNA sample and illustrate its potential use for the
analysis of criminal cases. In contrast to most previously used methods, we
directly model the peak height information and incorporates important artefacts
associated with the production of the EPG. Our model has a number of unknown
parameters, and we show that these can be estimated by the method of maximum
likelihood in the presence of multiple unknown contributors, and their
approximate standard errors calculated; the computations exploit a Bayesian
network representation of the model. A case example from a UK trial, as
reported in the literature, is used to illustrate the efficacy and use of the
model, both in finding likelihood ratios to quantify the strength of evidence,
and in the deconvolution of mixtures for the purpose of finding likely profiles
of one or more unknown contributors to a DNA sample. Our model is readily
extended to simultaneous analysis of more than one mixture as illustrated in a
case example. We show that combination of evidence from several samples may
give an evidential strength close to that of a single source trace and thus
modelling of peak height information provides for a potentially very efficient
mixture analysis.


title: Performance Regions in Compressed Sensing from Noisy Measurements

abstract:
  In this paper, compressed sensing with noisy measurements is addressed. The
theoretically optimal reconstruction error is studied by evaluating Tanaka's
equation. The main contribution is to show that in several regions, which have
different measurement rates and noise levels, the reconstruction error behaves
differently. This paper also evaluates the performance of the belief
propagation (BP) signal reconstruction method in the regions discovered. When
the measurement rate and the noise level lie in a certain region, BP is
suboptimal with respect to Tanaka's equation, and it may be possible to develop
reconstruction algorithms with lower error in that region.


title: Optimal Scheduling for Linear-Rate Multi-Mode Systems

abstract:
  Linear-Rate Multi-Mode Systems is a model that can be seen both as a subclass
of switched linear systems with imposed global safety constraints and as hybrid
automata with no guards on transitions. We study the existence and design of a
controller for this model that keeps the state of the system within a given
safe set for the whole time. A sufficient and necessary condition is given for
such a controller to exist as well as an algorithm that finds one in polynomial
time. We further generalise the model by adding costs on modes and present an
algorithm that constructs a safe controller which minimises the peak cost, the
average-cost or any cost expressed as a weighted sum of these two. Finally, we
present numerical simulation results based on our implementation of these
algorithms.


title:
The thermodynamics of self-gravitating systems in equilibrium is
  holographic

abstract:
  We show that, when we study the coexistence of general relativity with
thermodynamics, some physical properties that are usually thought of as
holographic and lying in the domain of quantum gravity can actually be accessed
even at the classical level. In particular, we demonstrate that the
thermodynamics of gravitating systems in equilibrium is fully specified by
variables defined on the system's boundary, namely, the boundary's geometry and
extrinsic curvature. Hence, information is non-trivially incorporated in
boundary variables because of the structure (the symmetries) of the classical
gravity theory, without any input from quantum theory (such as black hole
entropy).


title:
Reaching 10 ms single photon lifetimes for superconducting aluminum
  cavities

abstract:
  Three-dimensional microwave cavities have recently been combined with
superconducting qubits in the circuit quantum electrodynamics (cQED)
architecture. These cavities should have less sensitivity to dielectric and
conductor losses at surfaces and interfaces, which currently limit the
performance of planar resonators. We expect that significantly (>10^3) higher
quality factors and longer lifetimes should be achievable for 3D structures.
Motivated by this principle, we have reached internal quality factors greater
than 0.5x10^9 and intrinsic lifetimes of 0.01 seconds for multiple aluminum
superconducting cavity resonators at single photon energies and millikelvin
temperatures. These improvements could enable long lived quantum memories with
submicrosecond access times when strongly coupled to superconducting qubits.


title: Bounding the distinguishing number of infinite graphs

abstract:
  A group of permutations G of a set V is k-distinguishable if there exists a
partition of V into k parts such that only the identity permutation in G fixes
setwise all of the cells of the partition. The least cardinal number k such
that (G,V) is k-distinguishable is its distinguishing number. In particular, a
graph X is k-distinguishable if its automorphism group Aut(X) has
distinguishing number at most k in its action on the vertices of X.
  Various results in the literature demonstrate that when an infinite graph
fails to have some property, then often some finite subgraph is similarly
deficient. In this paper we show that whenever an infinite connected graph X is
not k-distinguishable (for a given cardinal k), then it contains a ball B of
finite radius whose distinguishing number is at least k. Moreover, this lower
bound cannot be sharpened, since for any integer k greater than 3 there exists
an infinite, locally finite, connected graph X that is not k-distinguishable
but in which every ball of finite radius is k-distinguishable.
  In the second half of this paper we show that a large distinguishing number
for an imprimitive graph X is traceable to a high distinguishing number either
of a block of imprimitivity or of the induced action of Aut(X) on the
corresponding system of imprimitivity. The distinguishing numbers of infinite
primitive graphs have been examined in detail in a previous paper by the
authors together with Tom W. Tucker.


title: Nucleon Excited States in N$_f$=2 lattice QCD

abstract:
  We investigate the excited states of the nucleon using $N_f=2$ twisted mass
gauge configurations with pion masses in the range of about 270 MeV to 450 MeV
and one ensemble of $N_f=2$ Clover fermions at almost physical pion mass. We
use two different sets of variational bases and study the resulting generalized
eigenvalue problem. We present results for the two lowest positive and negative
parity states.


title:
Quantum statistical modified entropic gravity as a theoretical basis for
  MOND

abstract:
  Considering the quantum statistics of the degrees of freedom on the
holographic screen it is shown that the ratio of the number of excited bulk
degrees of freedom to the number of excited surface degrees of freedom, is
given by the MOND interpolating function {\mu}. This relationship is shown to
hold also in AQUAL, and in the extension of MOND to de Sitter space. Based on
the relationship between the entropy, and the number of degrees of freedom on
the holographic screen, a simple expression, relating the MOND interpolating
function to the ratio of the two-dimensional entropy to Bekenstein-Hawking
entropy, is obtained. In terms of this expression MOND can be viewed as a
modification of gravity arising due to a bound on the maximum entropy for the
holographic screen.


title: Recommending Given Names

abstract:
  All over the world, future parents are facing the task of finding a suitable
given name for their child. This choice is influenced by different factors,
such as the social context, language, cultural background and especially
personal taste. Although this task is omnipresent, little research has been
conducted on the analysis and application of interrelations among given names
from a data mining perspective.
  The present work tackles the problem of recommending given names, by firstly
mining for inter-name relatedness in data from the Social Web. Based on these
results, the name search engine "Nameling" was built, which attracted more than
35,000 users within less than six months, underpinning the relevance of the
underlying recommendation task. The accruing usage data is then used for
evaluating different state-of-the-art recommendation systems, as well our new
NameRank algorithm which we adopted from our previous work on folksonomies and
which yields the best results, considering the trade-off between prediction
accuracy and runtime performance as well as its ability to generate
personalized recommendations. We also show, how the gathered inter-name
relationships can be used for meaningful result diversification of
PageRank-based recommendation systems.
  As all of the considered usage data is made publicly available, the present
work establishes baseline results, encouraging other researchers to implement
advanced recommendation systems for given names.


title: On higher order extensions for the fractional Laplacian

abstract:
  The technique of Caffarelli and Silvestre, characterizing the fractional
Laplacian as the Dirichlet-to-Neumann map for a function U satisfying an
elliptic equation in the upper half space with one extra spatial dimension, is
shown to hold for general positive, non-integer orders of the fractional
Laplace operator, by showing an equivalence between the H^s norm on the
boundary and a suitable higher-order seminorm of U.


title:
Approximation Algorithms for Energy Minimization in Cloud Service
  Allocation under Reliability Constraints

abstract:
  We consider allocation problems that arise in the context of service
allocation in Clouds. More specifically, we assume on the one part that each
computing resource is associated to a capacity constraint, that can be chosen
using Dynamic Voltage and Frequency Scaling (DVFS) method, and to a probability
of failure. On the other hand, we assume that the service runs as a set of
independent instances of identical Virtual Machines. Moreover, there exists a
Service Level Agreement (SLA) between the Cloud provider and the client that
can be expressed as follows: the client comes with a minimal number of service
instances which must be alive at the end of the day, and the Cloud provider
offers a list of pairs (price,compensation), this compensation being paid by
the Cloud provider if it fails to keep alive the required number of services.
On the Cloud provider side, each pair corresponds actually to a guaranteed
success probability of fulfilling the constraint on the minimal number of
instances. In this context, given a minimal number of instances and a
probability of success, the question for the Cloud provider is to find the
number of necessary resources, their clock frequency and an allocation of the
instances (possibly using replication) onto machines. This solution should
satisfy all types of constraints during a given time period while minimizing
the energy consumption of used resources. We consider two energy consumption
models based on DVFS techniques, where the clock frequency of physical
resources can be changed. For each allocation problem and each energy model, we
prove deterministic approximation ratios on the consumed energy for algorithms
that provide guaranteed probability failures, as well as an efficient
heuristic, whose energy ratio is not guaranteed.


title: Quaternary matroids are vf-safe

abstract:
  Binary delta-matroids are closed under vertex flips, which consist of the
natural operations of twist and loop complementation. In this note we provide
an extension of this result from GF(2) to GF(4). As a consequence, quaternary
matroids are "safe" under vertex flips (vf-safe for short). As an application,
we find that the matroid of a bicycle space of a quaternary matroid is
independent of the chosen representation. This extends a result of Vertigan [J.
Comb. Theory B (1998)] concerning the bicycle dimension of quaternary matroids.


title:
Comparative Measurements of Inverse Spin Hall and Magnetoresistance in
  YIG|Pt and YIG|Ta

abstract:
  We report on a comparative study of spin Hall related effects and
magnetoresistance in YIG|Pt and YIG|Ta bilayers. These combined measurements
allow to estimate the characteristic transport parameters of both Pt and Ta
layers juxtaposed to YIG: the spin mixing conductance $G_{\uparrow \downarrow}$
at the YIG$|$normal metal interface, the spin Hall angle $\Theta_{SH}$, and the
spin diffusion length $\lambda_{sd}$ in the normal metal. The inverse spin Hall
voltages generated in Pt and Ta by the pure spin current pumped from YIG
excited at resonance confirm the opposite signs of spin Hall angles in these
two materials. Moreover, from the dependence of the inverse spin Hall voltage
on the Ta thickness, we extract the spin diffusion length in Ta, found to be
$\lambda_{sd}^\text{Ta}=1.8\pm0.7$ nm. Both the YIG|Pt and YIG|Ta systems
display a similar variation of resistance upon magnetic field orientation,
which can be explained in the recently developed framework of spin Hall
magnetoresistance.


title:
Detailed Jarzynski Equality applied on a Logically Irreversible
  Procedure

abstract:
  A single bit memory system is made with a brownian particle held by an
optical tweezer in a double-well potential and the work necessary to erase the
memory is measured. We show that the minimum of this work is close to the
Landauer's bound only for very slow erasure procedure. Instead a detailed
Jarzynski equality allows us to retrieve the Landauer's bound independently on
the speed of this erasure procedure. For the two separated subprocesses, i.e.
the transition from state 1 to state 0 and the transition from state 0 to state
0, the Jarzynski equality does not hold but the generalized version links the
work done on the system to the probability that it returns to its initial state
under the time-reversed procedure.


title:
Positive scalar curvature, higher rho invariants and localization
  algebras

abstract:
  In this paper, we use localization algebras to study higher rho invariants of
closed spin manifolds with positive scalar curvature metrics. The higher rho
invariant is a secondary invariant and is closely related to positive scalar
curvature problems. The main result of the paper connects the higher index of
the Dirac operator on a spin manifold with boundary to the higher rho invariant
of the Dirac operator on the boundary, where the boundary is endowed with a
positive scalar curvature metric. Our result extends a theorem of Piazza and
Schick.


title:
The determinant of the Malliavin matrix and the determinant of the
  covariance matrix for multiple integrals

abstract:
  A well-known problem in Malliavin calculus concerns the relation between the
determinant of the Malliavin matrix of a random vector and the determinant of
its covariance matrix. We give an explicit relation between these two
determinants for couples of random vectors of multiple integrals. In
particular, if the multiple integrals are of the same order and this order is
at most 4, we prove that two random variables in the same Wiener chaos either
admit a joint density, either are proportional and that the result is not true
for random variables in Wiener chaoses of different orders.


title: A semi-local holographic minimal model

abstract:
  We present a conjecture on the complete spectrum of single-trace operators in
the infinite N limit of W(N) minimal model and evidences for the conjecture. We
further propose that the holographic dual of W(N) minimal model in the 't Hooft
limit is an unusual "semi-local" higher spin gauge theory on AdS3 x S^1. At
each point on the S^1 lives a copy of three-dimensional Vasiliev theory, that
contains an infinite tower of higher spin gauge fields coupled to a single
massive complex scalar propagating in AdS3. The Vasiliev theories at different
points on the S^1 are correlated only through the AdS3 boundary conditions on
the massive scalars. All but one single tower of higher spin symmetries are
broken by the boundary conditions.


title: Towards a theory of good SAT representations

abstract:
  We aim at providing a foundation of a theory of "good" SAT representations F
of boolean functions f. We argue that the hierarchy UC_k of unit-refutation
complete clause-sets of level k, introduced by the authors, provides the most
basic target classes, that is, F in UC_k is to be achieved for k as small as
feasible. If F does not contain new variables, i.e., F is equivalent (as a CNF)
to f, then F in UC_1 is similar to "achieving (generalised) arc consistency"
known from the literature (it is somewhat weaker, but theoretically much nicer
to handle). We show that for polysize representations of boolean functions in
this sense, the hierarchy UC_k is strict. The boolean functions for these
separations are "doped" minimally unsatisfiable clause-sets of deficiency 1;
these functions have been introduced in [Sloan, Soerenyi, Turan, 2007], and we
generalise their construction and show a correspondence to a strengthened
notion of irredundant sub-clause-sets. Turning from lower bounds to upper
bounds, we believe that many common CNF representations fit into the UC_k
scheme, and we give some basic tools to construct representations in UC_1 with
new variables, based on the Tseitin translation. Note that regarding new
variables the UC_1-representations are stronger than mere "arc consistency",
since the new variables are not excluded from consideration.


title:
Phonon Heat Conduction in Corrugated Silicon Nanowires Below the Casimir
  Limit

abstract:
  The thermal conductance of straight and corrugated monocrystalline silicon
nanowires has been measured between 0.3 K and 5 K. The difference in the
thermal transport between corrugated nanowires and straight ones demonstrates a
strong reduction in the mean free path of the phonons. This averaged mean free
path is remarkably smaller than the smaller diameter of the nanowire,
evidencing a phonon thermal transport reduced below the Casimir limit. Monte
Carlo simulations highlight that this effect can be attributed to significant
multiple scattering of ballistic phonons occuring on the corrugated surfaces.
This result suggests an original approach to transforming a monocrystalline
material into a phonon glass.


title: Every totally real algebraic integer is a tree eigenvalue

abstract:
  Graph eigenvalues are examples of totally real algebraic integers, i.e. roots
of real-rooted monic polynomials with integer coefficients. Conversely, the
fact that every totally real algebraic integer occurs as an eigenvalue of some
finite graph is a deep result, conjectured forty years ago by Hoffman, and
proved seventeen years later by Estes. This short paper provides an independent
and elementary proof of a stronger statement, namely that the graph may
actually be chosen to be a tree. As a by-product, our result implies that the
atoms of the limiting spectrum of $n\times n$ symmetric matrices with
independent Bernoulli$\,\left(\frac{c}{n}\right)$ entries ($c>0$ is fixed as
$n\to\infty$) are exactly the totally real algebraic integers. This settles an
open problem raised by Ben Arous (2010).


title:
Beyond position weight matrices: nucleotide correlations in
  transcription factor binding sites and their description

abstract:
  The identification of transcription factor binding sites (TFBSs) on genomic
DNA is of crucial importance for understanding and predicting regulatory
elements in gene networks. TFBS motifs are commonly described by Position
Weight Matrices (PWMs), in which each DNA base pair independently contributes
to the transcription factor (TF) binding, despite mounting evidence of
interdependence between base pairs positions. The recent availability of
genome-wide data on TF-bound DNA regions offers the possibility to revisit this
question in detail for TF binding {\em in vivo}. Here, we use available fly and
mouse ChIPseq data, and show that the independent model generally does not
reproduce the observed statistics of TFBS, generalizing previous observations.
We further show that TFBS description and predictability can be systematically
improved by taking into account pairwise correlations in the TFBS via the
principle of maximum entropy. The resulting pairwise interaction model is
formally equivalent to the disordered Potts models of statistical mechanics and
it generalizes previous approaches to interdependent positions. Its structure
allows for co-variation of two or more base pairs, as well as secondary motifs.
Although models consisting of mixtures of PWMs also have this last feature, we
show that pairwise interaction models outperform them. The significant pairwise
interactions are found to be sparse and found dominantly between consecutive
base pairs. Finally, the use of a pairwise interaction model for the
identification of TFBSs is shown to give significantly different predictions
than a model based on independent positions.

categories: q-bio.GN cond-mat.dis-nn physics.bio-ph q-bio.QM


title: Deep redshift topological lensing: strategies for the T^3 candidate

abstract:
  The 3-torus (T^3) FLRW model better fits the nearly zero large-scale
auto-correlation of the WMAP CMB sky maps than the infinite flat model. The T^3
model's WMAP parameters imply approximately equal-redshift topological lensing
at z \sim 6. We investigate observational strategies for rejecting the T^3
solution or providing candidate topologically lensed galaxy pairs. T^3
holonomies are applied to (i) existing z \sim 6 observations and (ii) simulated
observations, creating multiply connected catalogues. Corresponding simply
connected catalogues are generated. Each catalogue is analysed using a
successive filter method and collecting matched quadruples. Quadruple
statistics between the multiply and simply connected catalogues are compared.
The expected rejection of the hypothesis, or detection of candidate
topologically lensed galaxies, is possible at a significance of 5% for a pair
of T^3 axis-centred northern and southern surveys if photometric redshift
accuracy is \sigma(\zphot) < 0.01 for a pair of nearly complete 100 deg^2
surveys with a total of > 500 galaxies over 4.3 < z < 6.6, or for a pair of 196
deg^2 surveys with > 400 galaxies and \sigma(\zphot) < 0.02 over 4<z<7.
Dropping the maximum time interval in a pair from \Delta t =1 Gyr/h to \Delta t
=0.1 Gyr/h yields a requirement of \sigma(\zphot) < 0.005 or \sigma(\zphot) <
0.01, respectively. Millions of z \sim 6 galaxies will be observed over fields
of these sizes during the coming decades, implying much stronger constraints.
The question is not if the hypothesis will be rejected or confirmed, it is
when.


title: A new algorithm for Many to Many Matching with Demands and Capacities

abstract:
  Let A={a_1,a_2,...,a_s} and {b_1,b_2,...,b_t} with s+r=n, the many to many
point matching with demands and capacities matches each point a_i in A to at
least alpha_i and at most alpha_i points in B, and each point b_j in B to at
least beta_j and at most beta_j points in A for all 1 <= i <= s and 1 <= j <=
t. In this paper, we present an O(n^4) time and O(n) space algorithm for this
problem.


title:
Search for the CP symmetry violation in the decays of Ks mesons using
  the KLOE detector

abstract:
  The aim of this work was to determine the KS -> 3pi0 decay branching ratio
and a modulus of the eta000 parameter, defined as the ratio of amplitudes for
KS -> 3 pi0 to KL -> 3pi0 decays, which characterizes the CP symmetry violation
in this decay. The measurement has been carried out with the KLOE detector
operating at the phi-factory DAFNE in the Italian National Center for Nuclear
Physics in Frascati. The KS mesons were identified with high efficiency via
registration of these KL mesons which crossed the drift chamber without
decaying and then interacted with the KLOE electromagnetic calorimeter. The KS
four-momentum vector was then determined using the registered position of the
KL meson and the known momentum of the phi meson. Next, the search for the KS
-> 3pi0 -> 6gamma decay was carried out by the selection of events with six
gamma quanta which momenta were reconstructed using time and energy measured by
the electromagnetic calorimeter. To increase the signal over background ratio
after identification of the KS meson and requiring six reconstructed photons a
discriminant analysis is performed. It is based on kinematical fit, testing of
the signal and background hypotheses and exploiting of the differences in
kinematics of the KS decays into 2pi0 and 3pi0. Hence, we have obtained the
upper limit on the KS -> 3pi0 branching ratio at the 90% confidence level BR(KS
-> 3pi0)< 2.7 x 10^-8, which is almost five times lower than the latest
published result. The search for the KS -> 3pi0 decay presented in this work
failed to detect a signal of sufficient statistical significance. This upper
limit can be translated into a limit on the modulus of the eta000 parameter
amounting to: |eta000| < 0.009 at the 90% confidence level.