title: The TeV blazar Markarian 421 at the highest spatial resolution

abstract:
  We report the results obtained for the AGN Markarian 421 by model-fitting the
data in the visibility plane, studing the proper motion of jet components, the
light curve, and the spectral index of the jet features. We compare the radio
data with optical light curves obtained at the Steward Observatory, considering
also the optical polarization information. Mrk 421 has a bright nucleus and a
one-sided jet extending towards the north-west for a few parsecs. The
model-fits show that brightness distribution is well described using 6-7
circular Gaussian components, four of which are reliably identified at all
epochs; all components are effectively stationary except for component D, at
~0.4 mas from the core, whose motion is however subluminal. Analysis of the
light curve shows two different states, with the source being brighter and more
variable in the first half of 2011 than in the second half. The highest flux
density is reached in February. A comparison with the optical data reveals an
increase of the V magnitude and of the fractional polarization simultaneous
with the enhancement of the radio activity.


title:
Some properties of multi-qubit systems under effect of the Lorentz
  transformation

abstract:
  Effect of Lorentz transformation on some properties of multi-qubit systems is
investigated. It is shown that, properties like, the fidelity and entanglement
decay as the Wigner's angles increase, but can be improved, if all the
transformed particles are transformed with the same Wigner's angles. The upper
bounds of the average capacity of the GHZ state increases while it decreases
and more robust with the W-state as the Wigner's angle of the observer
decreases. Under Lorentz transformation, the tripartite states transform into
another equivalent states and hence no change on the efficiency of these states
to perform quantum information tasks.


title: Competitive dynamics of lexical innovations in multi-layer networks

abstract:
  We study the introduction of lexical innovations into a community of language
users. Lexical innovations, i.e., new terms added to people's vocabulary, play
an important role in the process of language evolution. Nowadays, information
is spread through a variety of networks, including, among others, online and
offline social networks and the World Wide Web. The entire system, comprising
networks of different nature, can be represented as a multi-layer network. In
this context, lexical innovations diffusion occurs in a peculiar fashion. In
particular, a lexical innovation can undergo three different processes: its
original meaning is accepted; its meaning can be changed or misunderstood
(e.g., when not properly explained), hence more than one meaning can emerge in
the population; lastly, in the case of a loan word, it can be translated into
the population language (i.e., defining a new lexical innovation or using a
synonym) or into a dialect spoken by part of the population. Therefore, lexical
innovations cannot be considered simply as information. We develop a model for
analyzing this scenario using a multi-layer network comprising a social network
and a media network. The latter represents the set of all information systems
of a society, e.g., television, the World Wide Web and radio. Furthermore, we
identify temporal directed edges between the nodes of these two networks. In
particular, at each time step, nodes of the media network can be connected to
randomly chosen nodes of the social network and vice versa. In so doing,
information spreads through the whole system and people can share a lexical
innovation with their neighbors or, in the event they work as reporters, by
using media nodes. Lastly, we use the concept of "linguistic sign" to model
lexical innovations, showing its fundamental role in the study of these
dynamics. Many numerical simulations have been performed.


title: Links of singularities up to regular homotopy

abstract:
  The abstract link L_d of the complex isolated singularity x^2 + y^2 + z^2 +
v^{2d} = 0 is diffeomorphic to S^3 \times S^2. We classify the embedded links
of these singularities up to regular homotopies precomposed with
diffeomorphisms of S^3 \times S^2. Let us denote by i_d the inclusion of L_d in
S^7. We show that for arbitrary diffeomorphisms \varphi_d of S^3 \times S^2
with L_d the compositions i_d \circ \varphi_d are image regularly homotopic for
two values d_1 and d_2 if and only if d_1-d_2 is even.


title:
Learning Tensors in Reproducing Kernel Hilbert Spaces with Multilinear
  Spectral Penalties

abstract:
  We present a general framework to learn functions in tensor product
reproducing kernel Hilbert spaces (TP-RKHSs). The methodology is based on a
novel representer theorem suitable for existing as well as new spectral
penalties for tensors. When the functions in the TP-RKHS are defined on the
Cartesian product of finite discrete sets, in particular, our main problem
formulation admits as a special case existing tensor completion problems. Other
special cases include transfer learning with multimodal side information and
multilinear multitask learning. For the latter case, our kernel-based view is
instrumental to derive nonlinear extensions of existing model classes. We give
a novel algorithm and show in experiments the usefulness of the proposed
extensions.


title:
Entire Solutions for Bistable Lattice Differential Equations with
  Obstacles

abstract:
  We consider scalar lattice differential equations posed on square lattices in
two space dimensions. Under certain natural conditions we show that wave-like
solutions exist when obstacles (characterized by "holes") are present in the
lattice. Our work generalizes to the discrete spatial setting the results
obtained in a paper of Berestycki, Hamel and Matano for the propagation of
waves around obstacles in continuous spatial domains. The analysis hinges upon
the development of sub and super-solutions for a class of discrete bistable
reaction-diffusion problems and on a generalization of a classical result due
to Aronson and Weinberger that concerns the spreading of localized
disturbances.


title:
Nonperturbative renormalization-group approach to fermion systems in the
  two-particle-irreducible effective action formalism

abstract:
  We propose a nonperturbative renormalization-group (NPRG) approach to fermion
systems in the two-particle-irreducible (2PI) effective action formalism, based
on an exact RG equation for the Luttinger-Ward functional. This approach
enables us to describe phases with spontaneously broken symmetries while
satisfying the Mermin-Wagner theorem. We show that it is possible to choose the
Hartree-Fock--RPA theory as initial condition of the RG flow and argue that the
2PI-NPRG is not restricted to the weak-coupling limit. An expansion of the
Luttinger-Ward functional about the minimum of the 2PI effective action
including only the two-particle 2PI vertex leads to nontrivial RG equations
where interactions between fermions and collective excitations naturally
emerge.


title: The Stability of Galaxy Disks

abstract:
  We calculate the stellar surface mass density (Sigma_*) and two-component
(gas+stars) disk stability (Q_RW) for 25 late-type galaxies from the DiskMass
Survey. These calculations are based on fits of a dynamical model to our
ionized-gas and stellar kinematic data performed using a Markov Chain Monte
Carlo sampling of the Bayesian posterior. Marginalizing over all galaxies, we
find a median value of Q_RW=2.0+/-0.9 at 1.5 scale lengths. We also find that
Q_RW is anti-correlated with the star-formation rate surface density
(Sigma_SFR), which can be predicted using a closed set of empirical scaling
relations. Finally, we find that the star-formation efficiency
(Sigma_SFR/Sigma_g) is correlated with Sigma_* and weakly anti-correlated with
Q_RW. The former is consistent with an equilibrium prediction of
Sigma_SFR/Sigma_g propto Sigma_*^{1/2}. Despite its order-of-magnitude range,
we find no correlation of Sigma_SFR/Sigma_g/Sigma_*^{1/2} with any other
physical quantity derived by our study.


title:
High-loop perturbative renormalization constants for Lattice QCD (II):
  three-loop quark currents for tree-level Symanzik improved gauge action and
  n_f=2 Wilson fermions

abstract:
  Numerical Stochastic Perturbation Theory was able to get three- (and even
four-) loop results for finite Lattice QCD renormalization constants. More
recently, a conceptual and technical framework has been devised to tame finite
size effects, which had been reported to be significant for (logarithmically)
divergent renormalization constants. In this work we present three-loop results
for fermion bilinears in the Lattice QCD regularization defined by tree-level
Symanzik improved gauge action and n_f=2 Wilson fermions. We discuss both
finite and divergent renormalization constants in the RI'-MOM scheme. Since
renormalization conditions are defined in the chiral limit, our results also
apply to Twisted Mass QCD, for which non-perturbative computations of the same
quantities are available. We emphasize the importance of carefully accounting
for both finite lattice space and finite volume effects. In our opinion the
latter have in general not attracted the attention they would deserve.


title: Dynamical axion in topological superconductors and superfluids

abstract:
  We consider dynamical axion phenomena in topological superconductors and
superfluids in three spatial dimensions in terms of the gravitoelectromagnetic
topological action, in which the axion field couples with mechanical rotation
under finite temperature gradient. The dynamical axion is induced by relative
phase fluctuations between topological and s-wave superconducting orders. We
show that an antisymmetric spin-orbit interaction which induces parity-mixing
of Cooper pairs enlarges the parameter region in which the dynamical axion
fluctuation appears as a low-energy excitation. We propose that the dynamical
axion increases the moment of inertia, and in the case of ac mechanical
rotation, i.e. a shaking motion with a finite frequency $\omega$, as $\omega$
approaches the dynamical axion fluctuation mass, the observation of this effect
becomes feasible.


title:
Non-equilibrium topological phase transitions in two-dimensional optical
  lattices

abstract:
  Recently, concepts of topological phases of matter are extended to
non-equilibrium systems, especially periodically driven systems. In this paper,
we construct an example which shows non-equilibrium topological phase
transitions using ultracold fermions in optical lattices. We show that the Rabi
oscillation has the possibility to induce non-equilibrium topological phases
which are classified into time-reversal-invariant topological insulators for a
two-orbital model of alkaline-earth-metal atoms. Furthermore we study the
non-equilibrium topological phases using time-dependent Schrieffer-Wolff-type
perturbation theory, and we obtain an analytical expression to describe the
topological phase transitions from a high-frequency limit of external driving
fields.


title:
Development of active edge pixel sensors and four-side buttable modules
  using vertical integration technologies

abstract:
  We present an R&D activity focused on the development of novel modules for
the upgrade of the ATLAS pixel system at the High Luminosity LHC (HL-LHC). The
modules consist of n-in-p pixel sensors, 100 or 200 $\mu$m thick, produced at
VTT (Finland) with an active edge technology, which considerably reduces the
dead area at the periphery of the device. The sensors are interconnected with
solder bump-bonding to the ATLAS FE-I3 and FE-I4 read-out chips, and
characterized with radioactive sources and beam tests at the CERN-SPS and DESY.
The results of these measurements will be discussed for devices before and
after irradiation up to a fluence of $5\times 10^{15}$ \neqcm. We will also
report on the R&D activity to obtain Inter Chip Vias (ICVs) on the ATLAS
read-out chip in collaboration with the Fraunhofer Institute EMFT. This step is
meant to prove the feasibility of the signal transport to the newly created
readout pads on the backside of the chips allowing for four side buttable
devices without the presently used cantilever for wire bonding. The read-out
chips with ICVs will be interconnected to thin pixel sensors, 75 $\mu$m and 150
$\mu$m thick, with the Solid Liquid Interdiffusion (SLID) technology, which is
an alternative to the standard solder bump-bonding.


title: Twisted $\Gamma$-Lie algebras and their vertex operator representations

abstract:
  Let $\Gamma$ be a generic subgroup of the multiplicative group $\mathbb{C}^*$
of nonzero complex numbers. We define a class of Lie algebras associated to
$\Gamma$, called twisted $\Gamma$-Lie algebras, which is a natural
generalization of the twisted affine Lie algebras. Starting from an arbitrary
even sublattice $Q$ of $\mathbb Z^N$ and an arbitrary finite order isometry of
$\mathbb Z^N$ preserving $Q$, we construct a family of twisted $\Gamma$-vertex
operators acting on generalized Fock spaces which afford irreducible
representations for certain twisted $\Gamma$-Lie algebras. As application, this
recovers a number of known vertex operator realizations for infinite
dimensional Lie algebras, such as twisted affine Lie algebras, extended affine
Lie algebras of type $A$, trigonometric Lie algebras of series $A$ and $B$,
unitary Lie algebras, and $BC$-graded Lie algebras.


title:
Computing Preferred Extensions in Abstract Argumentation: a SAT-based
  Approach

abstract:
  This paper presents a novel SAT-based approach for the computation of
extensions in abstract argumentation, with focus on preferred semantics, and an
empirical evaluation of its performances. The approach is based on the idea of
reducing the problem of computing complete extensions to a SAT problem and then
using a depth-first search method to derive preferred extensions. The proposed
approach has been tested using two distinct SAT solvers and compared with three
state-of-the-art systems for preferred extension computation. It turns out that
the proposed approach delivers significantly better performances in the large
majority of the considered cases.


title: A tower condition characterizing normality

abstract:
  We define left relative H-separable tower of rings and continue a study of
these begun by Sugano. It is proven that a progenerator extension has right
depth two if and only if the ring extension together with its right
endomorphism ring is a left relative H-separable tower. In particular, this
applies to twisted or ordinary Frobenius extensions with surjective Frobenius
homomorphism. For example, normality for Hopf subalgebras of finite-dimensional
Hopf algebras is also characterized in terms of this tower condition.


title: Single-field inflation \`a la generalized Chaplygin gas

abstract:
  In the simplest scenario for inflation, i. e. in the single-field inflation,
it is presented an inflaton field with properties equivalent to a generalized
Chaplygin gas. Their study is performed using the Hamilton-Jacobi approach to
cosmology. The main results are contrasted with the measurements recently
released by the Planck data, combined with the WMAP large-angle polarization.
If the measurements released by Planck for the scalar spectral index together
with its running are taken into account it is found a value for the
$\alpha$-parameter associated to the generalized Chaplygin gas given by $\alpha
= 0.2578 \pm 0.0009$.


title: Do System Test Cases Grow Old?

abstract:
  Companies increasingly use either manual or automated system testing to
ensure the quality of their software products. As a system evolves and is
extended with new features the test suite also typically grows as new test
cases are added. To ensure software quality throughout this process the test
suite is continously executed, often on a daily basis. It seems likely that
newly added tests would be more likely to fail than older tests but this has
not been investigated in any detail on large-scale, industrial software
systems. Also it is not clear which methods should be used to conduct such an
analysis. This paper proposes three main concepts that can be used to
investigate aging effects in the use and failure behavior of system test cases:
test case activation curves, test case hazard curves, and test case half-life.
To evaluate these concepts and the type of analysis they enable we apply them
on an industrial software system containing more than one million lines of
code. The data sets comes from a total of 1,620 system test cases executed a
total of more than half a million times over a time period of two and a half
years. For the investigated system we find that system test cases stay active
as they age but really do grow old; they go through an infant mortality phase
with higher failure rates which then decline over time. The test case half-life
is between 5 to 12 months for the two studied data sets.


title:
Classical systems can be contextual too: Analogue of the Mermin-Peres
  square

abstract:
  Contextuality lays at the heart of quantum mechanics. In the prevailing
opinion it is considered as a signature of 'quantumness' that classical
theories lack. However, this assertion is only partially justified. Although
contextuality is certainly true of quantum mechanics, it cannot be taken by
itself as discriminating against classical theories. Here we consider a
representative example of contextual behaviour, the so-called Mermin-Peres
square, and present a discrete toy model of a bipartite system which reproduces
the pattern of quantum predictions that leads to contradiction with the
assumption of non-contextuality. This illustrates that quantum-like contextual
effects have their analogues within classical models with epistemic constraints
such as limited information gain and measurement disturbance.


title:
Moduli spaces of stable pairs and non-abelian zeta functions of curves
  via wall-crossing

abstract:
  In this paper we study and relate the non-abelian zeta functions introduced
by Weng and invariants of the moduli spaces of arbitrary rank stable pairs over
curves. We prove a wall-crossing formula for the latter invariants and obtain
an explicit formula for these invariants in terms of the motive of a curve.
Previously, formulas for these invariants were known only for rank 2 due to
Thaddeus and for rank 3 due to Mu\~noz. Using these results we obtain an
explicit formula for the non-abelian zeta functions, we check the uniformity
conjecture by Weng for the ranks 2 and 3, and we prove the counting miracle
conjecture.


title:
Three `species' of Schr\"odinger cat states in an infinite-range spin
  model

abstract:
  We explore a transverse-field Ising model that exhibits both spontaneous
symmetry-breaking and eigenstate thermalization. Within its ferromagnetic
phase, the exact eigenstates of the Hamiltonian of any large but finite-sized
system are all Schr\"odinger cat states: superpositions of states with `up' and
`down' spontaneous magnetization. This model exhibits two dynamical phase
transitions {\it within} its ferromagnetic phase: In the lowest-temperature
phase the magnetization can macroscopically oscillate between up and down. The
relaxation of the magnetization is always overdamped in the remainder of the
ferromagnetic phase, which is divided in to phases where the system thermally
activates itself {\it over} the barrier between the up and down states, and
where it quantum tunnels.


title:
Fractional Interference Alignment: An Interference Alignment Scheme for
  Finite Alphabet Signals

abstract:
  Interference Alignment (IA) is a transmission scheme which achieves 1/2
Degrees-of-Freedom (DoF) per transmit-antenna per user. The constraints imposed
on the scheme are based on the linear receiver since conventional IA assumes
Gaussian signaling. However, when the transmitters employ Finite Alphabet (FA)
signaling, neither the conventional IA precoders nor the linear receiver are
optimal structures. Therefore, a novel Fractional Interference Alignment (FIA)
scheme is introduced when FA signals are used, where the alignment constraints
are now based on the non-linear, minimum distance (MD) detector. Since DoF is
defined only as signal-to-noise ratio tends to infinity, we introduce a new
metric called SpAC (number of Symbols transmitted-per-transmit
Antenna-per-Channel use) for analyzing the FIA scheme. The maximum SpAC is one,
and the FIA achieves any value of SpAC in the range [0,1]. The key motivation
for this work is that numerical simulations with FA signals and MD detector for
fixed SpAC (=1/2, as in IA) over a set of optimization problems, like
minimizing bit error rate or maximizing the mutual information, achieves a
significantly better error rate performance when compared to the existing
algorithms that minimize mean square error or maximize signal-to-interference
plus noise ratio.


title: Asymptotic Glosten Milgrom equilibrium

abstract:
  This paper studies the Glosten Milgrom model whose risky asset value admits
an arbitrary discrete distribution. Contrast to existing results on insider's
models, the insider's optimal strategy in this model, if exists, is not of
feedback type. Therefore a weak formulation of equilibrium is proposed. In this
weak formulation, the inconspicuous trade theorem still holds, but the
optimality for the insider's strategy is not enforced. However, the insider can
employ some feedback strategy whose associated expected profit is close to the
optimal value, when the order size is small. Moreover this discrepancy
converges to zero when the order size diminishes. The existence of such a weak
equilibrium is established, in which the insider's strategy converges to the
Kyle optimal strategy when the order size goes to zero.


title:
Wave-like avalanche propagation in the continuum field model of
  self-organized criticality

abstract:
  Travelling wave is identified as the mechanism of avalanche propagation in
the continuum SOC (self-organized critical) system. Recovering the hidden
causality based on a generalization of Fick's law, we lead the equivalent
continuum equation which has spatiotemporal nonlocality. Taking into account of
the hyperbolicity from the retarded response of the nonlocal kernel, it is
possible to capture the propagating avalanche in constant speed. Verifying the
computation, we analyze the evolution of instability as a nonlinear wave under
the control of the threshold dynamics, which imposes the "metastability" as the
survival condition of avalanche. Being consistent with the basic assumptions of
SOC theory, the result shows unified features of the existing models. This
provides a concept toward the SOC framework based on the physical principles of
transport process.


title: The Stagger-grid - A Grid of 3D Stellar Atmosphere Models

abstract:
  Theoretical atmosphere models provide the basis for a variety of applications
in astronomy. In simplified one-dimensional (1D) atmosphere models, convection
is usually treated with the mixing length theory despite its well-known
insufficiency, therefore, the superadiabatic regime is poorly rendered. Due to
the increasing computational power over the last decades, we are now capable to
compute large grids of realistic three-dimensional (3D) hydrodynamical model
atmospheres with the realistic treatment of the radiative transfer. We have
computed the Stagger-grid, a comprehensive grid of 3D atmosphere models for
late-type stars. In the presented contribution, we discuss initial results of
the grid by exploring global properties and mean stratifications of the 3D
models. Furthermore, we also depict the differences to classic 1D atmosphere
models.


title:
Lindblad equation for a non-interacting fermionic system: full-counting
  statistics

abstract:
  We develop a method of calculating the full-counting statistics for a
non-interacting fermionic system coupled to the memory-less reservoirs. The
evolution of the system is described by the Lindblad equation. By the basis
change the Liouvillian operator is brought to the quadratic form. This allows
us a straightforward calculation of any observable in the non-equilibrium
steady state. We introduce the counting field in the Lindblad equation which
brings us to the generating function and helps us to obtain all cumulants of
the charge transport. For the two-site system we give the expression for the
generating function. For system longer than two sites we perform numerical
investigations which suggest that it in a uniform system the cumulants of order
$k$ are independent of the size of the system for system sizes larger $k+1$.
The counting statistics from the Lindblad approach does not take into account
interference in the reservoirs which gives a decreased noise in comparison with
the Green function method which describes phase coherent leads. The current
obtained by two methods is the same, which relies on the current conservation.
The Fano factors are different (with a linear relation connecting them) and
allow to distinguish between memory-less and phase coherent reservoirs.


title: Zak phase of photons in optical waveguide lattices

abstract:
  Zak phase, i.e. the Berry phase acquired during an adiabatic motion of a
Bloch particle across the Brillouin zone, provides a measure of the topological
invariant of Bloch bands in one-dimensional crystalline potentials. Here a
photonic structure, based on engineered lattices of evanescently-coupled
optical waveguides, is proposed to detect Zak phase difference of photons
undergoing Bloch oscillations in topologically distinct Bloch bands of
dimerized superlattices.


title: Creep rupture as a non-homogeneous Poissonian process

abstract:
  Creep rupture of heterogeneous materials occurring under constant
sub-critical external loads is responsible for the collapse of engineering
constructions and for natural catastrophes. Acoustic monitoring of crackling
bursts provides microscopic insight into the failure process. Based on a fiber
bundle model, we show that the accelerating bursting activity when approaching
failure can be described by the Omori law. For long range load redistribution
the time series of bursts proved to be a non-homogeneous Poissonian process
with power law distributed burst sizes and waiting times. We demonstrate that
limitations of experiments such as finite detection threshold and time
resolution have striking effects on the characteristic exponents, which have to
be taken into account when comparing model calculations with experiments.
Recording events solely within the Omori time to failure the size distribution
of bursts has a crossover to a lower exponent which is promising for
forecasting the imminent catastrophic failure.


title: Isospin effects and symmetry energy studies with INDRA

abstract:
  The equation of state of asymmetric nuclear matter is still controversial, as
predictions at subsaturation as well as above normal density widely diverge. We
discuss several experimental results measured in heavy-ion collisions with the
INDRA array in the incident energy range 5-80 MeV/nucleon. In particular an
estimate of the density dependence of the symmetry energy is derived from
isospin diffusion results compared with a transport code: the potential part of
the symmetry energy linearly increases with the density. We demonstrate that
isospin equilibrium is reached in mid-central collisions for the two reactions
Ni+Au at 52 MeV/nucleon and Xe+Sn at 32 MeV/nucleon. New possible variables and
an improved modelization to investigate symmetry energy are discussed.


title:
Effective magnetic fields for photons in waveguide and coupled resonator
  lattices

abstract:
  A method to realize effective magnetic fields for photons in square lattices
of coupled optical waveguides or resonators is suggested, which is inspired by
an optical analogue of photon-assisted tunneling of atom optics. It is shown
that an artificial magnetic field can be achieved by application of an index
gradient and periodic lumped phase shifts or modulation of the propagation
constants/resonances, without the need to modulate the coupling strength.


title: The Super-Higgs Mechanism in Fluids

abstract:
  Supersymmetry is spontaneously broken when the field theory stress-energy
tensor has a non-zero vacuum expectation value. In local supersymmetric field
theories the massless gravitino and goldstino combine via the super-Higgs
mechanism to a massive gravitino. We study this mechanism in four-dimensional
fluids, where the vacuum expectation value of the stress-energy tensor breaks
spontaneously both supersymmetry and Lorentz symmetry. We consider both
constant as well as space-time dependent ideal fluids. We derive a formula for
the gravitino mass in terms of the fluid velocity, energy density and pressure.
We discuss some of the phenomenological implications.


title: Dynamics of asymmetric kinetic Ising systems revisited

abstract:
  The dynamics of an asymmetric kinetic Ising model is studied. Two schemes for
improving the existing mean-field description are proposed. In the first
scheme, we derive the formulas for instantaneous magnetization, equal-time
correlation, and time-delayed correlation, considering the correlation between
different local fields. To derive the time-delayed correlation, we emphasize
that the small correlation assumption adopted in previous work [M. M\'ezard and
J. Sakellariou, J. Stat. Mech., L07001 (2011)] is in fact not required. To
confirm the inference efficiency of our method, we perform extensive
simulations on single instances with either temporally constant external
driving fields or sinusoidal external fields. In the second scheme, we develop
an improved mean-field theory for instantaneous magnetization prediction
utilizing the notion of the cavity system in conjunction with a perturbative
expansion approach. Its efficiency is numerically confirmed by comparison with
the existing mean-field theory when partially asymmetric couplings are present.


title: Convective and absolute PT symmetry breaking in tight-binding lattices

abstract:
  We investigate the onset of parity-time ($\mathcal{PT}$) symmetry breaking in
non-Hermitian tight-binding lattices with spatially-extended loss/gain regions
in presence of an advective term. Similarly to the instability properties of
hydrodynamic open flows, it is shown that $\mathcal{PT}$ symmetry breaking can
be either absolute or convective. In the former case, an initially-localized
wave packet shows a secular growth with time at any given spatial position,
whereas in the latter case the growth is observed in a reference frame moving
at some drift velocity while decay occurs at any fixed spatial position. In the
convective unstable regime, $\mathcal{PT}$ symmetry is restored when the
spatial region of gain/loss in the lattice is limited (rather than extended).
We consider specifically a non-Hermitian extension of the Rice-Mele tight
binding lattice model, and show the existence of a transition from absolute to
convective symmetry breaking when the advective term is large enough. An
extension of the analysis to ac-dc-driven lattices is also presented, and an
optical implementation of the non-Hermitian Rice-Mele model is suggested, which
is based on light transport in an array of evanescently-coupled optical
waveguides with a periodically-bent axis and alternating regions of optical
gain and loss.


title:
Comment on "Trouble with the Lorentz Law of Force: Incompatibility with
  Special Relativity and Momentum Conservation [arXiv:1205.0096]"

abstract:
  In this Comment it is shown that the principle of relativity is naturally
satisfied and there is no paradox if an independent physical reality is
attributed to the four-dimensional (4D) geometric quantities (GQs) and not, as
usual, to the 3D quantities. Hence, there is no need either for the change of
the expression for the Lorentz force, but as a 4D GQ, or for the introduction
of some "hidden" 3D quantities.


title: Power Fluctuations and Irreversibility in Turbulence

abstract:
  The breaking of detailed balance, the symmetry between forward and backward
probability transition between two states, is crucial to understand
irreversible systems. In hydrodynamic turbulence, a far-from equilibrium
system, we observe a strong manifestation of the breaking of detailed balance
by following the evolution of the kinetic energy of individual fluid elements.
We found in all the flows that we have investigated that fluid elements
decelerate faster than they accelerate, giving rise to negative third moment of
energy increments, independently of space dimensionality. The exchange of
energy between fluid elements however is fundamentally different in two and
three dimensions. While pressure forces do not provide net energy change to
slow or fast particles in two dimensions, they tend to transfer energy from
{\it slow} to {\it fast} particles in three dimensions, possibly implying a
runaway of energy.


title: Online Classification Using a Voted RDA Method

abstract:
  We propose a voted dual averaging method for online classification problems
with explicit regularization. This method employs the update rule of the
regularized dual averaging (RDA) method, but only on the subsequence of
training examples where a classification error is made. We derive a bound on
the number of mistakes made by this method on the training set, as well as its
generalization error rate. We also introduce the concept of relative strength
of regularization, and show how it affects the mistake bound and generalization
performance. We experimented with the method using $\ell_1$ regularization on a
large-scale natural language processing task, and obtained state-of-the-art
classification performance with fairly sparse models.


title: Thompson Sampling in Dynamic Systems for Contextual Bandit Problems

abstract:
  We consider the multiarm bandit problems in the timevarying dynamic system
for rich structural features. For the nonlinear dynamic model, we propose the
approximate inference for the posterior distributions based on Laplace
Approximation. For the context bandit problems, Thompson Sampling is adopted
based on the underlying posterior distributions of the parameters. More
specifically, we introduce the discount decays on the previous samples impact
and analyze the different decay rates with the underlying sample dynamics.
Consequently, the exploration and exploitation is adaptively tradeoff according
to the dynamics in the system.


title: On the Phase Transitions That Cannot Materialize

abstract:
  The succession of suggested mechanisms of solid-state phase transitions -
Second-order, Lambda, Martensitic, Displacive, Topological, Order-Disorder,
Soft-mode, Incommensurate, Scaling and Quantum - are analyzed and explained why
they cannot be realized in nature. All of them assume a cooperative structural
rearrangement as opposed to the only real one which is simply a variant of the
crystal growth. Like all kinds of crystal growth, a solid state phase
transition proceeds by molecule-by-molecule building building the crystal of a
different structure, while the surrounding original crystal is used as the
building material.


title: Floquet bound states in the continuum

abstract:
  Quantum mechanics predicts that certain stationary potentials can sustain
bound states with an energy buried in the continuous spectrum of scattered
states, the so-called bound states in the continuum (BIC). Originally regarded
as mathematical curiosities, BIC have found an increasing interest in recent
years, particularly in quantum and classical transport of matter and optical
waves in mesoscopic and photonic systems where the underlying potential can be
judiciously tailored. Most of our knowledge of BIC is so far restricted to
static potentials. Here we introduce a new kind of BIC, referred to as Floquet
BIC, which corresponds to a normalizable Floquet state of a time-periodic
Hamiltonian with a quasienergy embedded into the spectrum of Floquet scattered
states. We discuss the appearance of Floquet BIC states in a tight-binding
lattice model driven by an ac field in the proximity of the dynamic
localization regime


title: Equations for formally real meadows

abstract:
  We consider the signatures $\Sigma_m=(0,1,-,+, \cdot, \ ^{-1})$ of meadows
and $(\Sigma_m, {\mathbf s})$ of signed meadows. We give two complete
axiomatizations of the equational theories of the real numbers with respect to
these signatures. In the first case, we extend the axiomatization of
zero-totalized fields by a single axiom scheme expressing formal realness; the
second axiomatization presupposes an ordering. We apply these completeness
results in order to obtain complete axiomatizations of the complex numbers.


title: The Boundary Layer in compact binaries

abstract:
  Disk accretion onto stars leads to the formation of a Boundary Layer (BL)
near the stellar surface where the disk makes contact with the star. Albeit a
large fraction of the total luminosity of the system originates from this tiny
layer connecting the accretion disk and the accreting object, its structure has
not been fully understood yet. It is the aim of this work, to obtain more
insight into the Boundary Layer around the white dwarf in compact binary
systems. There are still many uncertainties concerning the extent and
temperature of the BL and the rotation rate of the white dwarf. We perform
numerical hydrodynamical simulations, where the problem is treated in a
one-dimensional, radial approximation (slim disk). The turbulence is described
by the alpha parameter viscosity. We include both cooling from the disk
surfaces and radial radiation transport. The radiation energy is treated in the
one-temperature approximation. For a given M_dot our results show a strong
dependence on the stellar mass and rotation rate. Both, the midplane and the
effective temperature rise considerably with increasing stellar mass or
decreasing stellar rotation rate. Our simulations further show, that the
radiation energy and pressure are indeed important in the BL. However, some
models show a low optical depth in the BL, making it necessary to find a better
representation for optically thin regions. The combination of a high mass and a
small radius, such as in white dwarfs, can lead to an enormous energy release
in the BL, provided the WD rotates slowly. Since the radial extent of BLs is
typically very small (about 0.02 to 0.05 R_star), this leads to surface
temperatures of a few hundred thousand Kelvin. All of our models showed
subsonic infall velocities with Mach numbers of < 0.4 at most.


title: A Five-variable generalization of Ramanujan's reciprocity theorem

abstract:
  By virtue of Bailey's well-known bilateral 6\psi_6 summation formula and
Watson's transformation formula,we extend the four-variable generalization of
Ramanujan's reciprocity theorem due to Andrews to a five-variable one. Some
relevant new q-series identities including a new proof of Ramanujan's
reciprocity theorem and of Watson's quintuple product identity only based on
Jackson's transformation are presented.


title:
A characterization of boundary conditions yielding maximal monotone
  operators

abstract:
  We provide a characterization for maximal monotone realizations for a certain
class of (nonlinear) operators in terms of their corresponding boundary data
spaces. The operators under consideration naturally arise in the study of
evolutionary problems in mathematical physics. We apply our abstract
characterization result to Port-Hamiltonian systems and a class of frictional
boundary conditions in the theory of contact problems in visco-elasticity.


title: Two stream instabilities in degenerate quantum plasmas

abstract:
  The quantum mechanical effect on the plasma two-stream instability is studied
based on the dielectric function approach. The analysis suggests that the
degenerate plasma relevant to the inertial confinement fusion behaves
differently from classical plasmas when the electron drift velocity is
comparable to the Fermi velocity. For high wave vector comparable to the Fermi
wave vector, the degenerate quantum plasma has larger regime of the two-stream
instabilities than the classical plasma. A regime, where the plasma waves with
the frequency larger than 1.5 times of the Langmuir wave frequency become
unstable to the two-stream instabilities, is identified.


title: The Monster and black-box groups

abstract:
  We discuss ways in which the black-box model for computation is or is not
applicable to the Monster sporadic simple group. Conversely, we consider
whether methods of computation in the Monster can be generalised to other
situations, for example to groups of `cross-characteristic' type.


title:
Synthetic biocomputation design using supervised gene regulatory
  networks

abstract:
  The potential of synthetic biology techniques for designing complex cellular
circuits able to solve complicated computations opens a whole domain of
exploration, beyond experiments and theory. Such cellular circuits could be
used to carry out hard tasks involving decision-making, storage of information,
or signal processing. Since Gene Regulatory Networks (GRNs) are the best known
technical approach to synthetic designs, it would be desirable to know in
advance the potential of such circuits in performing tasks and how classical
approximations dealing with neural networks can be translated into GRNs. In
this paper such a potential is analyzed. Here we show that feed-forward GRNs
are capable of performing classic machine intelligence tasks. Therefore, two
important milestones in the success of Artificial Neural Networks are reached
for models of GRNs based on Hill equations, namely the back-propagation
algorithm and the proof that GRNs can approximate arbitrary positive functions.
Potential extensions and implications for synthetic designs are outlined.


title:
Pondermotive potential and Backward Raman Scattering in dense quantum
  plasmas

abstract:
  The response of dense quantum plasmas in the backward Raman scattering is
studied. The coefficients in the backward Raman scattering is found to be
underestimated (overestimated) in the classical theory if the excited Langmuir
wave has low-wave vector (high-wave vector). The second order quantum
perturbation theory shows that the second harmonic of the pondermotive
potential arises naturally even in a single particle motion contrary to the
classical plasmas.


title:
Asymptotic description of finite lifetime effects on the photon emission
  from a quark-gluon plasma

abstract:
  Direct photons play an important role as electromagnetic probes from the
quark-gluon plasma (QGP) which occurs during ultrarelativistic heavy-ion
collisions. In this context, it is of particular interest how the finite
lifetime of the QGP affects the resulting photon production. Earlier
investigations on this question were accompanied by a divergent contribution
from the vacuum polarization and by the remaining contributions not being
integrable in the ultraviolet (UV) domain. In this work, we provide a different
approach in which we do not consider the photon number density at finite times,
but for free asymptotic states obtained by switching the electromagnetic
interaction according to the Gell-Mann and Low theorem. This procedure
eliminates a possible unphysical contribution from the vacuum polarization and,
moreover, renders the photon number density UV integrable. It is emphasized
that the consideration of free asymptotic states is, indeed, crucial to obtain
such physically reasonable results.


title:
Bertini theorems for singular schemes and nearby cycles in mixed
  characteristic

abstract:
  We first study hyperplane sections of some singular schemes over a field. We
prove a Bertini theorem for the log smoothness of generic hyperplane sections
of a large class of log smooth schemes over a log point. We also give an
abstract generalization of the usual Bertini theorem for smoothness. We then
apply this result to the study of hyperplane sections of regular schemes over a
complete discrete valuation ring of characteristic zero with algebraically
closed residue field. Lastly, give an exposition of a result of Faltings which
states that one can compute the $p$-adic nearby cycles of smooth schemes over a
discrete valuation ring of mixed characteristic as Galois cohomology.


title: Epitaxial Growth of VO$_{2}$ by Periodic Annealing

abstract:
  We report the growth of ultrathin VO$_{2}$ films on rutile TiO$_{2}$ (001)
substrates via reactive molecular-beam epitaxy. The films were formed by the
cyclical deposition of amorphous vanadium and its subsequent oxidation and
transformation to VO$_{2}$ via solid-phase epitaxy. Significant metal-insulator
transitions were observed in films as thin as 2.3 nm, where a resistance change
{\Delta}R/R of 25 was measured. Low angle annular dark field scanning
transmission electron microscopy was used in conjunction with electron energy
loss spectroscopy to study the film/substrate interface and revealed the
vanadium to be tetravalent and the titanium interdiffusion to be limited to 1.6
nm.


title:
Division of the Energy Market into Zones in Variable Weather Conditions
  using Locational Marginal Prices

abstract:
  Adopting a zonal structure of electricity market requires specification of
zones' borders. One of the approaches to identify zones is based on clustering
of Locational Marginal Prices (LMP). The purpose of the paper is twofold: (i)
we extend the LMP methodology by taking into account variable weather
conditions and (ii) we point out some weaknesses of the method and suggest
their potential solutions. The offered extension comprises simulations based on
the Optimal Power Flow (OPF) algorithm and twofold clustering method. First,
LMP are calculated by OPF for each of scenario representing different weather
conditions. Second, hierarchical clustering based on Ward's criterion is used
on each realization of the prices separately. Then, another clustering method,
i.e. consensus clustering, is used to aggregate the results from all
simulations and to find the global division into zones. The offered method of
aggregation is not limited only to LMP methodology and is universal.


title:
A proof of Zhil'tsov's theorem on decidability of equational theory of
  epigroups

abstract:
  Epigroups are semigroups equipped with an additional unary operation called
pseudoinversion. Each finite semigroup can be considered as epigroup. We prove
the following theorem announced by Zhil'tsov in 2000: the equational theory of
the class of all epigroups coincides with the equational theory of the class of
all finite epigroups and is decidable. We show that the theory is not finitely
based but provide a transparent infinite basis for it.


title:
Analytical considerations for linear and nonlinear optimization of the
  TME cells. Application to the CLIC pre-damping rings

abstract:
  The theoretical minimum emittance cells are the optimal configurations for
achieving the absolute minimum emittance, if specific optics constraints are
satisfied at the middle of the cell's dipole. Linear lattice design options
based on an analytical approach for the theoretical minimum emittance cells are
presented in this paper. In particular the parametrization of the quadrupole
strengths and optics functions with respect to the emittance and drift lengths
is derived. A multi-parametric space can be then created with all the cell
parameters, from which one can chose any of them to be optimized. An
application of this approach are finally presented for the linear and
non-linear optimization of the CLIC Pre-damping rings.


title:
The Optimal Division of the Energy Market into Zones: Comparison of Two
  Methodologies under Variable Wind Conditions

abstract:
  We compare two competing methodologies of market zones identification under
the criterion of social welfare maximization: (i) consensus clustering of
Locational Marginal Prices over different wind scenarios and (ii) congestion
contribution identification with congested lines identified across variable
wind generation outputs. We test the division of market into zones based on
each of the two methodologies using a welfare criterion, i.e., comparing the
cost of supplying energy on uniform market (including readjustments made on a
balancing market to overcome the congestion) with cost on k-zone market. A
division which maximizes the welfare is considered as the optimum.


title: On Tate's conjecture for elliptic modular surfaces over finite fields

abstract:
  For $N\geq 3$, we show Tate's conjecture for the elliptic modular surface
$E(N)$ of level $N$ over $\mathbb{F}_p$ for a prime $p$ satisfying $p\equiv
1\mod N$ outside of a set of primes of density zero. We also prove a strong
form of Tate's conjecture for $E(N)$ over any finite field of characteristic
$p$ prime to $N$ under the assumption that the formal Brauer group of $E(N)$ is
of finite height.


title:
Almost \'etale extensions of Fontaine rings and log-crystalline
  cohomology in the semi-stable reduction case

abstract:
  Let $K$ be a field of characteristic zero complete for a discrete valuation,
with perfect residue field of characteristic $p>0$, and let $K^+$ be the
valuation ring of $K$. We relate the log-crystalline cohomology of the special
fibre of certain affine $K^+$-schemes $X=\text{Spec}(R)$ with semi-stable
reduction to the Galois cohomology of the fundamental group of the geometric
generic fibre $\pi_1(X_{\bar{K}})$ with coefficients in a Fontaine ring
constructed from $R$. This is based on Faltings' theory of almost \'etale
extensions.


title: Sivers Function in the Quasi-Classical Approximation

abstract:
  We calculate the Sivers function in semi-inclusive deep inelastic scattering
(SIDIS) and in the Drell-Yan process (DY) by employing the quasi-classical
Glauber-Mueller/ McLerran-Venugopalan approximation. Modeling the hadron as a
large "nucleus" with non-zero orbital angular momentum (OAM), we find that its
Sivers function receives two dominant contributions: one contribution is due to
the OAM, while another one is due to the local Sivers function density in the
nucleus. While the latter mechanism, being due to the "lensing" interactions,
dominates at large transverse momentum of the produced hadron in SIDIS or of
the di-lepton pair in DY, the former (OAM) mechanism is leading in saturation
power counting and dominates when the above transverse momenta become of the
order of the saturation scale. We show that the OAM channel allows for a
particularly simple and intuitive interpretation of the celebrated sign flip
between the Sivers functions in SIDIS and DY.


title:
Transient force effects, as predicted by Mbelek and Lachi\`{e}ze-Rey
  scalar tensor theory of gravitation

abstract:
  The scalar-tensor theory of gravitation proposed by Mbelek and
Lachi\`{e}ze-Rey have been recently shown to lead to some remarkable effects
beyond those initially explored by its authors. These new effects include a
possible explanation of the forces measured in asymmetric resonant microwave
cavities, and the variation of the amplitude of electromagnetic waves as they
propagate in static electric or magnetic fields. These rather unique effects
are excelent candidates for laboratory tests of this particular type of
scalar-tensor theory. In the present work we introduce an additional remarkable
effect of the theory: the generation of pulsed gravitational forces by
transient, quasi-stationary electromagnetic fields. In particular, we explore
the possible measurable effects of the simple experiment of turning on and off
the current in a coil. We show that with the proposed values of the constant in
the theory, this effect could resonantly excite a pendulum oscillation up to an
easily measurable magnitude.


title: tt Charge asymmetry at hadron colliders

abstract:
  We present the current status for the measurements of the ttbar charge
asymmetry at the Tevatron and LHC colliders.


title:
Program WWZ: Wavelet Analysis of Astronomical Signals With Irregularly
  Spaced Arguments

abstract:
  A program WWZ is introduced, which realizes the wavelet analysis using an
improved modification of the algorithm of the Morlet wavelet for a general case
of irregularly spaced data, which is typical for the databases available in
virtual observatories. Contrary to the well-known analogs, working with
regularly spaced (equidistant in time) arguments, we have implemented an
improved algorithm presented by Andronov, (1998KFNT...14..490A,
1999sss..conf...57A), which significantly increases the signal-to-noise ratio.
The program has been used to study semi-regular pulsating variable stars (U Del
et al.), but can be used for the analysis of signals of any nature.


title: Acceptance conditions for omega-languages and the Borel hierarchy

abstract:
  This paper investigates acceptance conditions for finite automata recognizing
omega-regular languages. As a first result, we show that, under any acceptance
condition that can be defined in the MSO logic, a finite automaton can
recognize at most omega-regular languages. Starting from this, the paper aims
at classifying acceptance conditions according to their expressive power and at
finding the exact position of the classes of omega-languages they induced
according to the Borel hierarchy. A new interesting acceptance condition is
introduced and fully characterized. A step forward is also made in the
understanding of the expressive power of (fin, =).


title: The Euler anomaly and scale factors in Liouville/Toda CFTs

abstract:
  The role played by the Euler anomaly in the dictionary relating sphere
partition functions of four dimensional theories of class $\mathcal{S}$ and two
dimensional nonrational CFTs is clarified. On the two dimensional side, this
involves a careful treatment of scale factors in Liouville/Toda correlators.
Using ideas from tinkertoy constructions for Gaiotto duality, a framework is
proposed for evaluating these scale factors. The representation theory of Weyl
groups plays a critical role in this framework.


title: A Theoretical and Experimental Comparison of the EM and SEM Algorithm

abstract:
  In this paper we provide a new analysis of the SEM algorithm. Unlike previous
work, we focus on the analysis of a single run of the algorithm. First, we
discuss the algorithm for general mixture distributions. Second, we consider
Gaussian mixture models and show that with high probability the update
equations of the EM algorithm and its stochastic variant are almost the same,
given that the input set is sufficiently large. Our experiments confirm that
this still holds for a large number of successive update steps. In particular,
for Gaussian mixture models, we show that the stochastic variant runs nearly
twice as fast.


title:
Linearized Alternating Direction Method with Parallel Splitting and
  Adaptive Penalty for Separable Convex Programs in Machine Learning

abstract:
  Many problems in machine learning and other fields can be (re)for-mulated as
linearly constrained separable convex programs. In most of the cases, there are
multiple blocks of variables. However, the traditional alternating direction
method (ADM) and its linearized version (LADM, obtained by linearizing the
quadratic penalty term) are for the two-block case and cannot be naively
generalized to solve the multi-block case. So there is great demand on
extending the ADM based methods for the multi-block case. In this paper, we
propose LADM with parallel splitting and adaptive penalty (LADMPSAP) to solve
multi-block separable convex programs efficiently. When all the component
objective functions have bounded subgradients, we obtain convergence results
that are stronger than those of ADM and LADM, e.g., allowing the penalty
parameter to be unbounded and proving the sufficient and necessary conditions}
for global convergence. We further propose a simple optimality measure and
reveal the convergence rate of LADMPSAP in an ergodic sense. For programs with
extra convex set constraints, with refined parameter estimation we devise a
practical version of LADMPSAP for faster convergence. Finally, we generalize
LADMPSAP to handle programs with more difficult objective functions by
linearizing part of the objective function as well. LADMPSAP is particularly
suitable for sparse representation and low-rank recovery problems because its
subproblems have closed form solutions and the sparsity and low-rankness of the
iterates can be preserved during the iteration. It is also highly
parallelizable and hence fits for parallel or distributed computing. Numerical
experiments testify to the advantages of LADMPSAP in speed and numerical
accuracy.


title:
Cyclotron resonance of single valley Dirac fermions in gapless HgTe
  quantum well

abstract:
  We report on Landau level spectroscopy studies of two HgTe quantum wells
(QWs) near or at the critical well thickness, where the band gap vanishes. In
magnetic fields up to $B$=16T, oriented perpendicular to the QW plane, we
observe a $\sqrt{B}$ dependence for the energy of the dominant cyclotron
resonance (CR) transition characteristic of two-dimensional Dirac fermions. The
dominant CR line exhibits either a single or double absorption lineshape for
the gapless or gapped QW. Using an effective Dirac model, we deduce the band
velocity of single valley Dirac fermions in gapless HgTe quantum wells,
$v_F=6.4 \times10^5$ m/s, and interpret the double absorption of the gapped QW
as resulting from the addition of a small relativistic mass.


title: Covering Pairs in Directed Acyclic Graphs

abstract:
  The Minimum Path Cover problem on directed acyclic graphs (DAGs) is a
classical problem that provides a clear and simple mathematical formulation for
several applications in different areas and that has an efficient algorithmic
solution. In this paper, we study the computational complexity of two
constrained variants of Minimum Path Cover motivated by the recent introduction
of next-generation sequencing technologies in bioinformatics. The first problem
(MinPCRP), given a DAG and a set of pairs of vertices, asks for a minimum
cardinality set of paths "covering" all the vertices such that both vertices of
each pair belong to the same path. For this problem, we show that, while it is
NP-hard to compute if there exists a solution consisting of at most three
paths, it is possible to decide in polynomial time whether a solution
consisting of at most two paths exists. The second problem (MaxRPSP), given a
DAG and a set of pairs of vertices, asks for a path containing the maximum
number of the given pairs of vertices. We show its NP-hardness and also its
W[1]-hardness when parametrized by the number of covered pairs. On the positive
side, we give a fixed-parameter algorithm when the parameter is the maximum
overlapping degree, a natural parameter in the bioinformatics applications of
the problem.


title: Bounded Scalar Perturbations in Bouncing Brane World Cosmologies

abstract:
  We examine the dynamics of scalar perturbations in closed
Friedmann-Lema\^itre-Robertson- Walker (FLRW) universes in the framework of
Brane World theory with a timelike extra dimension. In this scenario, the
unperturbed Friedmann equations contain additional terms arising from the
bulk-brane interaction that implement non-singular bounces in the models with a
cosmological constant and non-interacting perfect fluids. The structure of the
phase-space of the models allows for two basic configurations, namely, one
bounce solutions or eternal universes. Assuming that the matter content of the
model is given by dust and radiation, we derive the dynamical field equations
for scalar hydrodynamical perturbations considering either a conformally flat
(de Sitter) bulk or a perturbed bulk. We perform a numerical analysis which can
shed some light on the study of cosmological scalar perturbations in bouncing
brane world models. From a mathematical point of view we show that although the
bounce enhances the amplitudes of scalar perturbations for one bounce models in
the case of a de Sitter bulk, the amplitudes of the perturbations remain
sufficiently small and bounded relative to the background values up to a
certain scale. For one bounce models in the case of a perturbed bulk the
amplitudes of all perturbations (apart from the Weyl fluid energy density)
remain sufficiently small and bounded relative to the background values for any
scale of the perturbations. We also discuss and compare the stability and
bounded behaviour of the perturbations in the late accelerated phase of one
bounce solutions. For eternal universes we argue that some of these features
are maintained only for early times (typically of the order of the first
bounce). In this sense we show that eternal solutions are highly unstable
configurations considering the background model of this paper.


title: Index Distribution of the Ginibre Ensemble

abstract:
  Complex systems, and in particular random neural networks, are often
described by randomly interacting dynamical systems with no specific symmetry.
In that context, characterizing the number of relevant directions necessitates
fine estimates on the Ginibre ensemble. In this Letter, we compute analytically
the probability distribution of the number of eigenvalues $N_R$ with modulus
greater than $R$ (the index) of a large $N\times N$ random matrix in the real
or complex Ginibre ensemble. We show that the fraction $N_R/N=p$ has a
distribution scaling as $\exp(-\beta N^2 \psi_R(p))$ with $\beta=1$
(respectively $\beta=1/2$) for the complex (resp. real) Ginibre ensemble. For
any $p\in[0,1]$, the equilibrium spectral densities as well as the rate
function $\psi_R(p)$ are explicitly derived. This function displays a third
order phase transition at the critical (minimum) value $p^*_R=1-R^2$,
associated to a phase transition of the Coulomb gas. We deduce that, in the
central regime, the fluctuations of the index $N_R$ around its typical value
$p^*_R N$ scale as $N^{1/3}$.


title:
Tunneling, Remanence, and Frustration in Dysprosium based Endohedral
  Single Molecule Magnets

abstract:
  A single molecule magnet (SMM) can maintain its magnetization direction over
a long period of time [1,2]. It consists in a low number of atoms that
facilitates the understanding and control of the ground state, which is
essential in future applications such as high-density information storage or
quantum computers [3,4]. Endohedral fullerenes realize robust, nanometer sized,
and chemically protected magnetic clusters that are not found as free species
in nature. Here we demonstrate how adding one, two, or three dysprosium atoms
to the carbon cage results in three distinct magnetic ground states. The
significantly different hysteresis curves demonstrate the decisive influence of
the number of magnetic moments and their interactions. At zero field the
comparison relates tunneling of the magnetization, with remanence, and
frustration. The ground state of the tridysprosium species turns out to be one
of the simplest realizations of a frustrated, ferromagnetically coupled
magnetic system.


title: Spin constraints on nuclear energy density functionals

abstract:
  The Gallagher-Moszkowski rule in the spectroscopy of odd-odd nuclei imposes a
new spin constraint on the energy functionals for self-consistent mean field
theory. The commonly used parameterization of the effective three-body
interaction in the Gogny and Skyrme families of energy functionals is
ill-suited to satisfy the spin constraint. In particular, the Gogny
parameterization of the three-body interaction has the opposite spin dependence
to that required by the observed spectra. The two-body part has a correct sign,
but in combination the rule is violated as often as not. We conclude that a new
functional form is needed for the effective three-body interaction that can
take into better account the different spin-isospin channels of the
interaction.


title:
Distributional semantics beyond words: Supervised learning of analogy
  and paraphrase

abstract:
  There have been several efforts to extend distributional semantics beyond
individual words, to measure the similarity of word pairs, phrases, and
sentences (briefly, tuples; ordered sets of words, contiguous or
noncontiguous). One way to extend beyond words is to compare two tuples using a
function that combines pairwise similarities between the component words in the
tuples. A strength of this approach is that it works with both relational
similarity (analogy) and compositional similarity (paraphrase). However, past
work required hand-coding the combination function for different tasks. The
main contribution of this paper is that combination functions are generated by
supervised learning. We achieve state-of-the-art results in measuring
relational similarity between word pairs (SAT analogies and SemEval~2012 Task
2) and measuring compositional similarity between noun-modifier phrases and
unigrams (multiple-choice paraphrase questions).


title: One Quantifier Alternation in First-Order Logic with Modular Predicates

abstract:
  Adding modular predicates yields a generalization of first-order logic FO
over words. The expressive power of FO[<,MOD] with order comparison $x<y$ and
predicates for $x \equiv i \mod n$ has been investigated by Barrington,
Compton, Straubing and Therien. The study of FO[<,MOD]-fragments was initiated
by Chaubard, Pin and Straubing. More recently, Dartois and Paperman showed that
definability in the two-variable fragment FO2[<,MOD] is decidable. In this
paper we continue this line of work.
  We give an effective algebraic characterization of the word languages in
Sigma2[<,MOD]. The fragment Sigma2 consists of first-order formulas in prenex
normal form with two blocks of quantifiers starting with an existential block.
In addition we show that Delta2[<,MOD], the largest subclass of Sigma2[<,MOD]
which is closed under negation, has the same expressive power as two-variable
logic FO2[<,MOD]. This generalizes the result FO2[<] = Delta2[<] of Therien and
Wilke to modular predicates. As a byproduct, we obtain another decidable
characterization of FO2[<,MOD].


title: Phase diagrams of Janus fluids with up-down constrained orientations

abstract:
  A class of binary mixtures of Janus fluids formed by colloidal spheres with
the hydrophobic hemispheres constrained to point either up or down are studied
by means of Gibbs ensemble Monte Carlo simulations and simple analytical
approximations. These fluids can be experimentally realized by the application
of an external static electrical field. The gas-liquid and demixing phase
transitions in five specific models with different patch-patch affinities are
analyzed. It is found that a gas-liquid transition is present in all the
models, even if only one of the four possible patch-patch interactions is
attractive. Moreover, provided the attraction between like particles is
stronger than between unlike particles, the system demixes into two subsystems
with different composition at sufficiently low temperatures and high densities.


title: PPF - A Parallel Particle Filtering Library

abstract:
  We present the parallel particle filtering (PPF) software library, which
enables hybrid shared-memory/distributed-memory parallelization of particle
filtering (PF) algorithms combining the Message Passing Interface (MPI) with
multithreading for multi-level parallelism. The library is implemented in Java
and relies on OpenMPI's Java bindings for inter-process communication. It
includes dynamic load balancing, multi-thread balancing, and several
algorithmic improvements for PF, such as input-space domain decomposition. The
PPF library hides the difficulties of efficient parallel programming of PF
algorithms and provides application developers with the necessary tools for
parallel implementation of PF methods. We demonstrate the capabilities of the
PPF library using two distributed PF algorithms in two scenarios with different
numbers of particles. The PPF library runs a 38 million particle problem,
corresponding to more than 1.86 GB of particle data, on 192 cores with 67%
parallel efficiency. To the best of our knowledge, the PPF library is the first
open-source software that offers a parallel framework for PF applications.


title: The QuickReduce data reduction pipeline for the WIYN One Degree Imager

abstract:
  Optimizing one's observing strategy while at the telescope relies on knowing
the current observing conditions and the obtained data quality. In particular
the latter is not straight forward with current wide-field imagers, such as the
WIYN One Degree Imager (ODI), currently consisting of 13 detectors, each of
them read out in 64 independent cells.
  Here we present a fast data reduction software for ODI, optimized for a first
data inspection during acquisition at the the telescope, but capable enough for
science-quality data reductions. The pipeline is coded in pure python with
minimal additional requirements. It is installed on the ODI observer's
interface and publicly available from the author's webpage. It performs all
basic reduction steps as well as more advanced corrections for pupil-ghost
removal, fringe correction and masking of persistent pixels. Additional
capabilities include adding an accurate astrometric WCS solution based on the
2MASS reference system as well as photometric zeropoint calibration for frames
covered by the SDSS foot-print.
  The pipeline makes use of multiple CPU-cores wherever possible, resulting in
an execution time of only a few seconds per frame. As such this QuickReduce
pipeline offers the ODI observer a convenient way to closely monitor data
quality, a necessity to optimize the observing strategy during the night.


title: Higher-order structure and epidemic dynamics in clustered networks

abstract:
  Clustering is typically measured by the ratio of triangles to all triples,
open or closed. Generating clustered networks, and how clustering affects
dynamics on networks, is reasonably well understood for certain classes of
networks \cite{vmclust, karrerclust2010}, e.g., networks composed of lines and
non-overlapping triangles. In this paper we show that it is possible to
generate networks which, despite having the same degree distribution and equal
clustering, exhibit different higher-order structure, specifically, overlapping
triangles and other order-four (a closed network motif composed of four nodes)
structures. To distinguish and quantify these additional structural features,
we develop a new network metric capable of measuring order-four structure
which, when used alongside traditional network metrics, allows us to more
accurately describe a network's topology. Three network generation algorithms
are considered: a modified configuration model and two rewiring algorithms. By
generating homogeneous networks with equal clustering we study and quantify
their structural differences, and using SIS (Susceptible-Infected-Susceptible)
and SIR (Susceptible-Infected-Recovered) dynamics we investigate
computationally how differences in higher-order structure impact on epidemic
threshold, final epidemic or prevalence levels and time evolution of epidemics.
Our results suggest that characterising and measuring higher-order network
structure is needed to advance our understanding of the impact of network
topology on dynamics unfolding on the networks.


title:
Extreme orbital evolution from hierarchical secular coupling of two
  giant planets

abstract:
  Observations of exoplanets over the last two decades have revealed a new
class of Jupiter-size planets with orbital periods of a few days, the so-called
"hot Jupiters". Recent measurements using the Rossiter-McLaughlin effect have
shown that many (~ 50%) of these planets are misaligned; furthermore, some (~
15%) are even retrograde with respect to the stellar spin axis. Motivated by
these observations, we explore the possibility of forming retrograde orbits in
hierarchical triple configurations consisting of a star-planet inner pair with
another giant planet, or brown dwarf, in a much wider orbit. Recently Naoz et
al. (2011) showed that in such a system, the inner planet's orbit can flip back
and forth from prograde to retrograde, and can also reach extremely high
eccentricities. Here we map a significant part of the parameter space of
dynamical outcomes for these systems. We derive strong constraints on the
orbital configurations for the outer perturber that could lead to the formation
of hot Jupiters with misaligned or retrograde orbits. We focus only on the
secular evolution, neglecting other dynamical effects such as mean-motion
resonances, as well as all dissipative forces. For example, with an inner
Jupiter-like planet initially on a nearly circular orbit at 5 AU, we show that
a misaligned hot Jupiter is likely to be formed in the presence of a more
massive planetary companion (> 2 MJ) within 140 AU of the inner system, with
mutual inclination 50 degrees and eccentricity above 0.25. This is in striking
contrast to the test-particle approximation, where an almost perpendicular
configuration can still cause large eccentricity excitations, but flips of an
inner Jupiter-like planet are much less likely to occur. The constraints we
derive can be used to guide future observations, and, in particular, searches
for more distant companions in systems containing a hot Jupiter.


title: Global Structure of Conformal Theories in the SU(3) Gauge Theory

abstract:
  We investigate SU(3) gauge theories in four dimensions with Nf fundamental
fermions, on a lattice using the Wilson fermion. Clarifying the vacuum
structure in terms of Polyakov loops in spatial directions and properties of
temporal propagators using a new method "local analysis", we conjecture that
the "conformal region" exists together with the confining region and the
deconfining region in the phase structure parametrized by beta and K, both in
the cases of the large Nf QCD within the conformal window (referred as
Conformal QCD) with an IR cutoff and small Nf QCD at T/Tc>1 with Tc being the
chiral transition temperature (referred as High Temperature QCD).
  Our numerical simulation on a lattice of the size 16^3 x 64 shows the
following evidence of the conjecture. In the conformal region we find the
vacuum is the nontrivial Z(3) twisted vacuum modified by non-perturbative
effects and temporal propagators of meson behave at large t as a power-law
corrected Yukawa-type decaying form. The transition from the conformal region
to the deconfining region or the confining region is a sharp transition between
different vacua and therefore it suggests a first order transition both in
Conformal QCD and in High Temperature QCD.
  Within our fixed lattice simulation, we find that there is a precise
correspondence between Conformal QCD and High Temperature QCD in the temporal
propagators under the change of the parameters Nf and T/Tc respectively. In
particular, we find the correspondence between Conformal QCD with Nf = 7 and
High Temperature QCD with Nf=2 at T ~ 2 Tc being in close relation to a meson
unparticle model. From this we estimate the anomalous mass dimension gamma* =
1.2 (1) for Nf=7. We also show that the asymptotic state in the limit T/Tc -->
infty is a free quark state in the Z(3) twisted vacuum.


title: Geometric view on noneikonal waves

abstract:
  An axiomatic theory of classical nondissipative waves is proposed that is
constructed based on the definition of a wave as a multidimensional oscillator.
Waves are represented as abstract vectors $|\psi\rangle$ in the appropriately
defined space $\Psi$ with a Hermitian metric. The metric is usually
positive-definite but can be more general in the presence of negative-energy
waves (which are typically unstable and must not be confused with
negative-frequency waves). The very form of wave equations is derived from
properties of $\Psi$. The generic wave equation is shown to be a quantumlike
Schrodinger equation; hence one-to-one correspondence with the mathematical
framework of quantum mechanics is established, and the quantum-mechanical
machinery becomes applicable to classical waves "as is". The classical wave
action is defined as the density operator, $|\psi\rangle\langle\psi|$. The
coordinate and momentum spaces, not necessarily Euclidean, need not be
postulated but rather emerge when applicable. Various kinetic equations flow as
projections of the von Neumann equation for $|\psi\rangle\langle\psi|$. The
previously known action conservation theorems for noneikonal waves and the
conventional Wigner-Weyl-Moyal formalism are generalized and subsumed under a
unifying invariant theory. Whitham's equations are recovered as the
corresponding fluid limit in the geometrical-optics approximation. The
Liouville equation is also yielded as a special case, yet in a somewhat
different limit; thus ray tracing, and especially nonlinear ray tracing, is
found to be more subtle than commonly assumed. Applications of this
axiomatization are also discussed, briefly, for some characteristic equations.


title:
Viscoelastic Effects in Avalanche Dynamics: A Key to Earthquake
  Statistics

abstract:
  In many complex systems a continuous input of energy over time can be
suddenly relaxed in the form of avalanches. Conventional avalanche models
disregard the possibility of internal dynamical effects in the inter-avalanche
periods, and thus miss basic features observed in some real systems. We address
this issue by studying a model with viscoelastic relaxation, showing how
coherent oscillations of the stress field can emerge spontaneously. Remarkably,
these oscillations generate avalanche patterns that are similar to those
observed in seismic phenomena.


title: Static Gauge and Energy Spectrum of Single-mode Strings in AdS_5xS^5

abstract:
  Motivated by the notorious difficulties in determining the first quantum
corrections to the spectrum of short strings in AdS_5xS^5 from first
principles, we study closed bosonic strings in this background employing a
static gauge. In this gauge the world-sheet Hamiltonian density is constant
along the extension of the string and directly proportional to the square of
the spacetime energy. We quantize this system in a minisuperspace approach, in
which we consider only a single AdS_5 string mode excitation next to an
arbitrary particle like zero-mode contribution in the full AdS_5xS^5
background. We determine the quantum spectrum using this method to the
next-to-next-to-leading order in the large 't Hooft coupling expansion. We
argue for an ordering prescription which should arise from supersymmetrization
and indeed recover the integrability based predictions for the spectrum of the
lightest excitation, dual to the Konishi field scaling dimensions. The higher
excitations fail to agree, but this is shown to be a consequence of the string
mode truncation employed. Despite this simple setup, our system reveals
intriguing features, such as a close connection to particles in AdS_6,
classical integrability and preservation of the isometries of AdS_5xS^5 at the
quantum level.


title:
Identification of a convolution kernel in a control problem for the heat
  equation with a boundary memory term

abstract:
  We consider the evolution of the temperature $u$ in a material with thermal
memory characterized by a time-dependent convolution kernel $h$. The material
occupies a bounded region $\Omega$ with a feedback device controlling the
external temperature located on the boundary $\Gamma$. Assuming both $u$ and
$h$ unknown, we formulate an inverse control problem for an integrodifferential
equation with a nonlinear and nonlocal boundary condition. Existence and
uniqueness results of a solution to the inverse problem are proved.


title: On the degeneration of tunnel numbers under connected sum

abstract:
  We show that, for any integer $n\ge 3$, there is a prime knot $k$ such that
(1) $k$ is not meridionally primitive, and (2) for every $m$-bridge knot $k'$
with $m\leq n$, the tunnel numbers satisfy $t(k\# k')\le t(k)$. This gives
counterexamples to a conjecture of Morimoto and Moriah on tunnel number under
connected sum and meridionally primitive knots.


title: Pathologies of the Brauer-Manin obstruction

abstract:
  We construct a conic bundle over an elliptic curve over a real quadratic
field that is a counterexample to the Hasse principle not explained by the
\'etale Brauer-Manin obstruction. We also give simple examples of threefolds
with the same property that are families of 2-dimensional quadrics, and discuss
some other examples and general properties of the Brauer-Manin obstruction.


title:
Non-extremal and non-BPS extremal five-dimensional black strings from
  generalized special real geometry

abstract:
  We construct non-extremal as well as extremal black string solutions in
minimal five-dimensional supergravity coupled to vector multiplets using
dimensional reduction to three Euclidean dimensions. Our method does not assume
that the scalar manifold is a symmetric space, and applies as well to a class
of non-supersymmetric theories governed by a generalization of special real
geometry. We find that five-dimensional black string solutions correspond to
geodesics in a specific totally geodesic para-K\"ahler submanifold of the
scalar manifold of the dimensionally reduced theory, and identify the subset of
geodesics that corresponds to regular black string solutions in five
dimensions. BPS and non-BPS extremal solutions are distinguished by whether the
corresponding geodesics are along the eigendirections of the para-complex
structure or not, a characterization which carries over to non-supersymmetric
theories. For non-extremal black strings the values of the scalars at the outer
and inner horizon are not independent integration constants but determined by
certain functions of the charges and moduli. By lifting solutions from three to
four dimensions we obtain non-extremal versions of small black holes, and find
that while the outer horizon takes finite size, the inner horizon is still
degenerate.


title: Airflow in a Multiscale Subject-Specific Breathing Human Lung Model

abstract:
  The airflow in a subject-specific breathing human lung is simulated with a
multiscale computational fluid dynamics (CFD) lung model. The three-dimensional
(3D) airway geometry beginning from the mouth to about 7 generations of airways
is reconstructed from the multi-detector row computed tomography (MDCT) image
at the total lung capacity (TLC). Along with the segmented lobe surfaces, we
can build an anatomically-consistent one-dimensional (1D) airway tree spanning
over more than 20 generations down to the terminal bronchioles, which is
specific to the CT resolved airways and lobes (J Biomech 43(11): 2159-2163,
2010). We then register two lung images at TLC and the functional residual
capacity (FRC) to specify subject-specific CFD flow boundary conditions and
deform the airway surface mesh for a breathing lung simulation (J Comput Phys
244:168-192, 2013). The 1D airway tree bridges the 3D CT-resolved airways and
the registration-derived regional ventilation in the lung parenchyma, thus a
multiscale model. Large eddy simulation (LES) is applied to simulate airflow in
a breathing lung (Phys Fluids 21:101901, 2009). In this fluid dynamics video,
we present the distributions of velocity, pressure, vortical structure, and
wall shear stress in a breathing lung model of a normal human subject with a
tidal volume of 500 ml and a period of 4.8 s. On exhalation, air streams from
child branches merge in the parent branch, inducing oscillatory jets and
elongated vortical tubes. On inhalation, the glottal constriction induces
turbulent laryngeal jet. The sites where high wall shear stress tends to occur
on the airway surface are identified for future investigation of
mechanotransduction.


title: Spherical Cows in the Sky with Fab Four

abstract:
  We explore spherically symmetric static solutions in a subclass of unitary
scalar-tensor theories of gravity, called the `Fab Four' models. The weak field
large distance solutions may be phenomenologically viable, but only if the
Gauss-Bonnet term is negligible. Only in this limit will the Vainshtein
mechanism work consistently. Further, classical constraints and unitarity
bounds constrain the models quite tightly. Nevertheless, in the limits where
the range of individual terms at large scales is respectively Kinetic Braiding,
Horndeski, and Gauss-Bonnet, the horizon scale effects may occur while the
theory satisfies Solar system constraints and, marginally, unitarity bounds. On
the other hand, to bring the cutoff down to below a millimeter constrains all
the couplings scales such that `Fab Fours' can't be heard outside of the Solar
system.


title:
Squashing model for detectors and applications to quantum key
  distribution protocols

abstract:
  We develop a framework that allows a description of measurements in Hilbert
spaces that are smaller than their natural representation. This description,
which we call a "squashing model", consists of a squashing map that maps the
input states of the measurement from the original Hilbert space to the smaller
one, followed by a targeted prescribed measurement on the smaller Hilbert
space. This framework has applications in quantum key distribution, but also in
other cryptographic tasks, as it greatly simplifies the theoretical analysis
under adversarial conditions.


title: Parallelism of the measures in non-Markovian environments

abstract:
  There are various measures to compute correlation in various conditions, but
none of them can be used publicly, because each of them has abnormality in
their calculations or behaviors. These abnormalities do not depend on genus of
environments. Therefore, in this work we will show correlation diversity of
evolution that is computed by each measure for two oscillators with their
non-Markovian stochastic reservoir. We will see that while the situation is the
same for all of them, they will have symmetrical plots. In more expressive
words, process of the measures has a kind of parallelism when angular momentum
and time are increasing. In the other hand, increase of quantum correlation
under the non-Markovian drive is observable in all of studied measures. Also,
in all of them (quantum discord's measures and entanglement's measures)recently
occurrences are done.


title: On dual toric complete intersection codes

abstract:
  In this paper we study duality for evaluation codes on intersections of d
hypersurfaces with given d-dimensional Newton polytopes, so called toric
complete intersection codes. In particular, we give a condition for such a code
to be quasi-self-dual. In the case of d=2 it reduces to a combinatorial
condition on the Newton polygons. This allows us to give an explicit
construction of dual and quasi-self-dual toric complete intersection codes. We
provide a list of examples over the field of 16 elements.


title: Aspects of randomness in neural graph structures

abstract:
  In the past two decades, significant advances have been made in understanding
the structural and functional properties of biological networks, via
graph-theoretic analysis. In general, most graph-theoretic studies are
conducted in the presence of serious uncertainties, such as major undersampling
of the experimental data. In the specific case of neural systems, however, a
few moderately robust experimental reconstructions do exist, and these have
long served as fundamental prototypes for studying connectivity patterns in the
nervous system. In this paper, we provide a comparative analysis of these
"historical" graphs, both in (unmodified) directed and (often symmetrized)
undirected forms, and focus on simple structural characterizations of their
connectivity. We find that in most measures the networks studied are captured
by simple random graph models; in a few key measures, however, we observe a
marked departure from the random graph prediction. Our results suggest that the
mechanism of graph formation in the networks studied is not well-captured by
existing abstract graph models, such as the small-world or scale-free graph.


title: Internal DLA for cylinders

abstract:
  We show that space-time averages of the fluctuations of internal DLA on a
cylinder Z_N x Z converge in law to the Gaussian free field.


title: Kermions

abstract:
  In the framework of quantum field theory in curved space-time, we study the
quantization of a massless fermion field on a non-extremal Kerr black hole. The
key theme in this note is the fundamental difference between scalar and fermion
fields for the process of defining quantum states. In particular, we define two
new states for fermions on Kerr which cannot be defined for quantum scalar
fields on Kerr. These two states are the analogues of the standard Boulware and
Hartle-Hawking states on a Schwarzschild black hole.


title:
The use of segmented cathode of a drift tube for designing a track
  detector with a high rate capability

abstract:
  Detector rate capability is one of the main parameters for designing a new
detector for high energy physics due to permanent rise of the beam luminosity
of modern accelerators. One of the widely used detectors for particle track
reconstruction is a straw detector based on drift tubes. The rate capability of
such detectors is limited by the parameters of readout electronics. The
traditional method of increasing detector rate capability is increasing their
granularity (a number of readout channels) by reducing the straw diameter
and/or by dividing the straw anode wire into two parts (for decreasing the rate
per readout channel). A new method of designing straw detectors with a high
rate capability is presented and tested. The method is based on dividing the
straw cathode into parts and independent readout of each part.


title: On the Calabi composition of multiple affine hyperspheres

abstract:
  In this paper, we explicitly construct the Calabi composition of multiple
affine hyperspheres possibly including some points viewing as 0-dimensional
hypersheres. Then we compute all the basic affine invariants of the composed
affine hyperspheres, proving that the composed affine hypersphere is symmetric
one if and only if each of its composing factors of positive dimension is
symmetric.


title:
A response to arXiv:1310.2791: A self-consistent public catalogue of
  voids and superclusters in the SDSS Data Release 7 galaxy surveys

abstract:
  Recently, Nadathur & Hotchkiss (2013) submitted a paper discussing a new
cosmic void catalog. This paper includes claims about the void catalog
described in Sutter et al. (2012). In this note, we respond to those claims,
clarify some discrepancies between the text of Sutter et al. (2012) and the
most recent version of the catalog, and provide some comments on the
differences between our catalog and that of Nadathur & Hotchkiss (2013). All
updates and documentation for our catalog are available at
http://www.cosmicvoids.net.


title:
ALMA observations of the molecular gas in the debris disk of the 30 Myr
  old star HD 21997

abstract:
  The 30 Myr old A3-type star HD 21997 is one of the two known debris dust
disks having a measurable amount of cold molecular gas. With the goal of
understanding the physical state, origin, and evolution of the gas in young
debris disks, we obtained CO line observations with the Atacama Large
Millimeter/submillimeter Array (ALMA). Here we report on the detection of 12CO
and 13CO in the J=2-1 and J=3-2 transitions and C18O in the J=2-1 line. The gas
exhibits a Keplerian velocity curve, one of the few direct measurements of
Keplerian rotation in young debris disks. The measured CO brightness
distribution could be reproduced by a simple star+disk system, whose parameters
are r_in < 26 AU, r_out = 138 +/- 20 AU, M_*=1.8 +0.5 -0.2 M_Sun, and i = 32.6
+/- 3.1 degrees. The total CO mass, as calculated from the optically thin C18O
line, is about (4-8) x 10^-2 M_Earth, while the CO line ratios suggest a
radiation temperature on the order of 6-9 K. Comparing our results with those
obtained for the dust component of the HD 21997 disk from the ALMA continuum
observations by Mo\'or et al., we conclude that comparable amounts of CO gas
and dust are present in the disk. Interestingly, the gas and dust in the HD
21997 system are not co-located, indicating a dust-free inner gas disk within
55 AU of the star. We explore two possible scenarios for the origin of the gas.
A secondary origin, which involves gas production from colliding or active
planetesimals, would require unreasonably high gas production rates and would
not explain why the gas and dust are not co-located. We propose that HD 21997
is a hybrid system where secondary debris dust and primordial gas coexist. HD
21997, whose age exceeds both the model predictions for disk clearing and the
ages of the oldest T Tauri-like or transitional gas disks in the literature,
may be a key object linking the primordial and the debris phases of disk
evolution.


title:
ALMA continuum observations of a 30 Myr old gaseous debris disk around
  HD 21997

abstract:
  Circumstellar disks around stars older than 10 Myr are expected to be
gas-poor. There are, however, two examples of old (30-40 Myr) debris-like disks
containing a detectable amount of cold CO gas. Here we present ALMA and
Herschel Space Observatory observations of one of these disks, around HD 21997,
and study the distribution and origin of the dust and its connection to the
gas. Our ALMA continuum images at 886um clearly resolve a broad ring of
emission within a diameter of ~4.5 arcsec, adding HD 21997 to the dozen debris
disks resolved at (sub)millimeter wavelengths. Modeling the morphology of the
ALMA image with a radiative transfer code suggests inner and outer radii of ~55
and ~150 AU, and a dust mass of 0.09 M_Earth. Our data and modeling hints at an
extended cold outskirt of the ring. Comparison with the morphology of the CO
gas in the disk reveals an inner dust-free hole where gas nevertheless can be
detected. Based on dust grain lifetimes, we propose that the dust content of
this gaseous disk is of secondary origin produced by planetesimals. Since the
gas component is probably primordial, HD 21997 is one of the first known
examples of a hybrid circumstellar disk, a so-far little studied late phase of
circumstellar disk evolution.


title:
Transverse target single-spin asymmetry in inclusive electroproduction
  of charged pions and kaons

abstract:
  Single-spin asymmetries were investigated in inclusive electroproduction of
charged pions and kaons from transversely polarized protons at the HERMES
experiment. The asymmetries were studied as a function of the azimuthal angle
$\psi$ about the beam direction between the target-spin direction and the
hadron production plane, the transverse hadron momentum relative to the
direction of the incident beam, and the Feynman variable $x_F$. The
$\sin(\psi)$ amplitudes are positive for positive pions and kaons, slightly
negative for negative pions and consistent with zero for negative kaons, with
particular transverse-momentum but weak $x_F$ dependences. Especially large
asymmetries are observed for two small subsamples of events, where also the
scattered electron was recorded by the spectrometer.


title: The q-Division Ring and its Fixed Rings

abstract:
  We prove that the fixed ring of the $q$-division ring $k_q(x,y)$ under any
finite group of monomial automorphisms is isomorphic to $k_q(x,y)$ for the same
$q$. In a similar manner, we also show that this phenomenon extends to an
automorphism that is defined only on $k_q(x,y)$ and does not restrict to
$k_q[x^{\pm1},y^{\pm1}]$. We then use these results to answer several questions
posed by Artamonov and Cohn about the endomorphisms and automorphisms of
$k_q(x,y)$.


title: Nonmonotonic Effects of Migration in Subdivided Populations

abstract:
  The influence of migration on the stochastic dynamics of subdivided
populations is still an open issue in various evolutionary models. We develop
here a self-consistent mean-field-like method in order to determine the effects
of migration on relevant nonequilibrium properties, such as the mean fixation
time. If evolution strongly favors coexistence of species (e.g., balancing
selection), the mean fixation time develops an unexpected minimum as a function
of the migration rate. Our analysis hinges only on the presence of a separation
of time scales between local and global dynamics and therefore it carries over
to other nonequilibrium processes in physics, biology, ecology, and social
sciences.


title: White dwarfs constraints on dark sector models with light particles

abstract:
  The white dwarf luminosity function is well understood in terms of standard
model physics and leaves little room for exotic cooling mechanisms related to
the possible existence of new weakly interacting light particles. This puts
significant constraints on the parameter space of models that contain a massive
dark photon and light dark sector particles.


title:
A Spectral Transform Method for Singular Sturm-Liouville Problems with
  Applications to Energy Diffusion in Plasma Physics

abstract:
  We develop a spectrally accurate numerical method to compute solutions of a
model partial differential equation used in plasma physics to describe
diffusion in velocity space due to Fokker-Planck collisions. The solution is
represented as a discrete and continuous superposition of normalizable and
non-normalizable eigenfunctions via the spectral transform associated with a
singular Sturm-Liouville operator. We present a new algorithm for computing the
spectral density function of the operator that uses Chebyshev polynomials to
extrapolate the value of the Titchmarsh-Weyl $m$-function from the complex
upper half-plane to the real axis. The eigenfunctions and density function are
rescaled and a new formula for the limiting value of the $m$-function is
derived to avoid amplification of roundoff errors when the solution is
reconstructed. The complexity of the algorithm is also analyzed, showing that
the cost of computing the spectral density function at a point grows less
rapidly than any fractional inverse power of the desired accuracy. A WKB
analysis is used to prove that the spectral density function is real analytic.
Using this new algorithm, we highlight key properties of the partial
differential equation and its solution that have strong implications on the
optimal choice of discretization method in large-scale plasma physics
computations.