title: Dynamical Friction in a Gas: The Supersonic Case

abstract:
  Any gravitating mass traversing a relatively sparse gas experiences a
retarding force created by its disturbance of the surrounding medium. In a
previous contribution (Lee & Stahler 2011), we determined this dynamical
friction force when the object's velocity was subsonic. We now extend our
analysis to the supersonic regime. As before, we consider small perturbations
created in the gas far from the gravitating object, and thereby obtain the net
influx of linear momentum over a large, bounding surface. Various terms in the
perturbation series formally diverge, necessitating an approximate treatment of
the flow streamlines. Nevertheless, we are able to derive exactly the force
itself. As in the subsonic case, we find that F=Mdot*V, where Mdot is the rate
of mass accretion onto the object and V its instantaneous velocity with respect
to distant background gas. Our force law holds even when the object is porous
(e.g., a galaxy) or is actually expelling mass in a wind. Quantitatively, the
force in the supersonic regime is less than that derived analytically by
previous researchers, and is also less than was found in numerical simulations
through the mid 1990s. We urge simulators to revisit the problem using modern
numerical techniques. Assuming our result to be correct, it is applicable to
many fields of astrophysics, ranging from exoplanet studies to galactic
dynamics.


title:
Uncovering the deeply embedded AGN activity in the nuclear regions of
  the interacting galaxy Arp299

abstract:
  We present mid-infrared (MIR) 8-13micron spectroscopy of the nuclear regions
of the interacting galaxy Arp299 (IC694+NGC3690) obtained with CanariCam (CC)
on the 10.4m Gran Telescopio Canarias (GTC). The high angular resolution
(~0.3-0.6arcsec) of the data allows us to probe nuclear physical scales between
60 and 120pc, which is a factor of 10 improvement over previous MIR
spectroscopic observations of this system. The GTC/CC spectroscopy displays
evidence of deeply embedded Active Galactic Nucleus (AGN) activity in both
nuclei. The GTC/CC nuclear spectrum of NGC3690/Arp299-B1 can be explained as
emission from AGN-heated dust in a clumpy torus with both a high covering
factor and high extinction along the line of sight. The estimated bolometric
luminosity of the AGN in NGC3690 is 3.2(+/-0.6)x10^44 erg/s. The nuclear GTC/CC
spectrum of IC694/Arp299-A shows 11.3micron polycyclic aromatic hydrocarbon
(PAH) emission stemming from a deeply embedded (A_V~24mag) region of less than
120pc in size. There is also a continuum-emitting dust component. If associated
with th putative AGN in IC694, we estimate that it would be approximately 5
times less luminous than the AGN in NGC3690. The presence of dual AGN activity
makes Arp299 a good example to study such phenomenon in the early coalescence
phase of interacting galaxies.


title: Photo-oxidation of Graphene in the Presence of Water

abstract:
  Oxygen molecules are found to exhibit non-negligible reactivity with graphene
under strong light irradiation in the presence of water. The reaction is
triggered by the laser Raman spectroscopy measurement itself, and the D band
(ca. 1340 cm-1) becomes larger as the laser irradiation is prolonged. The
electronic transport properties of the graphene derivative are also
investigated and both the electron and hole mobility are found to be reduced.
These results are attributed to oxidation of graphene. This primitive
modification method can be exploited to manipulate the structural and
electronic properties of graphene.


title:
Non-equilibrium statistical mechanics of the heat bath for two Brownian
  particles

abstract:
  We propose a new look at the heat bath for two Brownian particles, in which
the heat bath as a `system' is both perturbed and sensed by the Brownian
particles. Non-local thermal fluctuation give rise to bath-mediated static
forces between the particles. Based on the general sum-rule of the linear
response theory, we derive an explicit relation linking these forces to the
friction kernel describing the particles' dynamics. The relation is
analytically confirmed in the case of two solvable models and could be
experimentally challenged. Our results point out that the inclusion of the
environment as a part of the whole system is important for micron- or
nano-scale physics.


title: Towards flavored bound states beyond rainbows and ladders

abstract:
  We give a snapshot of recent progress in solving the Dyson-Schwinger equation
with a beyond rainbow-ladder ansatz for the dressed quark-gluon vertex which
includes ghost contributions. We discuss the motivations for this approach with
regard to heavy-flavored bound states and form factors and briefly describe
future steps to be taken.


title:
Chaos and dynamical trends in barred galaxies: bridging the gap between
  N-body simulations and time-dependent analytical models

abstract:
  Self-consistent N-body simulations are efficient tools to study galactic
dynamics. However, using them to study individual trajectories (or ensembles)
in detail can be challenging. Such orbital studies are important to shed light
on global phase space properties, which are the underlying cause of observed
structures. The potentials needed to describe self-consistent models are
time-dependent. Here, we aim to investigate dynamical properties
(regular/chaotic motion) of a non-autonomous galactic system, whose
time-dependent potential adequately mimics certain realistic trends arising
from N-body barred galaxy simulations. We construct a fully time-dependent
analytical potential, modeling the gravitational potentials of disc, bar and
dark matter halo, whose time-dependent parameters are derived from a
simulation. We study the dynamical stability of its reduced time-independent
2-degrees of freedom model, charting the different islands of stability
associated with certain orbital morphologies and detecting the chaotic and
regular regions. In the full 3-degrees of freedom time-dependent case, we show
representative trajectories experiencing typical dynamical behaviours, i.e.,
interplay between regular and chaotic motion for different epochs. Finally, we
study its underlying global dynamical transitions, estimating fractions of
(un)stable motion of an ensemble of initial conditions taken from the
simulation. For such an ensemble, the fraction of regular motion increases with
time.


title: Toposes, quantales and C* algebras in the atomic case

abstract:
  We start by reviewing the relation between toposes and Grothendieck
quantales. We improve results of previous work on this relation by giving both
a characterisation of the map from the tensor product of two internal
sup-lattices to another sup-lattice and a description of the category of
internal locales of a topos in terms of the associated Grothendieck quantale.
We then construct a convolution product, corresponding to internal composition
of matrices, on the set of positive lower semi-continuous functions on the
underlying locale of the quantale attached to a topos. In good cases, this
convolution product does restrict into a well defined convolution product on a
subset of the set of continuous functions and defines a convolution C* algebra
attached to the quantale. In the last part of this article we investigate in
details these attached C* algebras in the special case of an atomic topos. In
this situation the related Grothendieck quantale corresponds to a
hypergroupoid. Relatively simple finiteness conditions on this hypergroupoid
appear in order to obtain an interesting C* algebra. This algebra corresponds
to a hypergroupoid algebra which comes endowed with an arithmetic sub-algebra
and a time evolution. We conclude by showing that the existence of a
hypergroupoid satisfying all the requirements attached to a specified atomic
topos is equivalent to the fact that the topos is locally decidable and locally
separated. Also in this situation the time evolution only depends on the topos
and is described by a (canonical) principal Q+* bundle on the topos. The
BC-system and more generally the double cosets algebras are special cases of
this situation.


title: Gate-controlled ultraviolet photo-etching of graphene edges

abstract:
  The chemical reactivity of graphene under ultraviolet (UV) light irradiation
is investigated under positive and negative gate electric fields. Graphene
edges are selectively etched when negative gate voltages are applied, while the
reactivity is significantly suppressed for positive gate voltages. Oxygen
adsorption onto graphene is significantly affected by the Fermi level of the
final state achieved during previous electrical measurements. UV irradiation
after negative-to-positive gate sweeps causes predominant oxygen desorption,
while UV irradiation after gate sweeps in the opposite direction causes etching
of graphene edges.


title:
Fractal energy spectrum of a polariton gas in a Fibonacci quasi-periodic
  potential

abstract:
  We report on the study of a polariton gas confined in a quasi-periodic one
dimensional cavity, described by a Fibonacci sequence. Imaging the polariton
modes both in real and reciprocal space, we observe features characteristic of
their fractal energy spectrum such as the opening of mini-gaps obeying the gap
labeling theorem and log-periodic oscillations of the integrated density of
states. These observations are accurately reproduced solving an effective 1D
Schr\"{o}dinger equation, illustrating the potential of cavity polaritons as a
quantum simulator in complex topological geometries.


title:
Existence and nonuniqueness of segregated solutions to a class of
  cross-diffusion systems

abstract:
  We study the the Dirichlet problem for the cross-diffusion system \[
\partial_tu_i=\operatorname{div}\left(a_iu_i\nabla
(u_1+u_2)\right)+f_i(u_1,u_2),\quad i=1,2,\quad a_i=const>0, \] in the cylinder
$Q=\Omega\times (0,T]$. The functions $f_i$ are assumed to satisfy the
conditions $f_1(0,r)=0$, $f_2(s,0)=0$, $f_1(0,r)$, $f_2(s,0)$ are locally
Lipschitz-continuous. It is proved that for suitable initial data $u_0$, $v_0$
the system admits segregated solutions $(u_1,u_2)$ such that $u_i\in
L^{\infty}(Q)$, $u_1+u_2\in C^{0}(\overline{Q})$, $u_1+u_2>0$ and $u_1\cdot
u_2=0$ everywhere in $Q$. We show that the segregated solution is not unique
and derive the equation of motion of the surface $\Gamma$ which separates the
parts of $Q$ where $u_1>0$, or $u_2>0$. The equation of motion of $\Gamma$ is a
modification of the Darcy law in filtration theory. Results of numerical
simulation are presented.


title:
Scaled Brownian motion as a mean field model for continuous time random
  walks

abstract:
  We consider scaled Brownian motion (sBm), a random process described by a
diffusion equation with explicitly time-dependent diffusion coefficient $D(t) =
D_0 t^{\alpha - 1}$ (Batchelor's equation) which, for $\alpha < 1$, is often
used for fitting experimental data for subdiffusion of unclear genesis. We show
that this process is a close relative of subdiffusive continuous-time random
walks and describes the motion of the center of mass of a cloud of independent
walkers. It shares with subdiffusive CTRW its non-stationary and non-ergodic
properties. The non-ergodicity of sBm does not however go hand in hand with
strong difference between its different realizations: its heterogeneity
("ergodicity breaking") parameter tends to zero for long trajectories.


title:
Faber-Krahn inequality for anisotropic eigenvalue problems with Robin
  boundary conditions

abstract:
  In this paper we study the main properties of the first eigenvalue and its
eigenfunctions of a class of highly nonlinear elliptic operators in a bounded
Lipschitz domain, assuming a Robin boundary condition. Moreover, we prove a
Faber-Krahn inequality.


title: Logarithmic Exotic Conformal Galilean Algebras

abstract:
  Logarithmic representations of the conformal Galilean algebra (CGA) and the
Exotic Conformal Galilean algebra ({\sc ecga}) are constructed. This can be
achieved by non-decomposable representations of the scaling dimensions or the
rapidity indices, specific to conformal galilean algebras. Logarithmic
representations of the non-exotic CGA lead to the expected constraints on
scaling dimensions and rapidities and also on the logarithmic contributions in
the co-variant two-point functions. On the other hand, the {\sc ecga} admits
several distinct situations which are distinguished by different sets of
constraints and distinct scaling forms of the two-point functions. Two distinct
realisations for the spatial rotations are identified as well. The first
example of a reducible, but non-decomposable representation, without
logarithmic terms in the two-point function is given.

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


title:
Ergodicity for a stochastic Hodgkin-Huxley model driven by
  Ornstein-Uhlenbeck type input

abstract:
  We consider a model describing a neuron and the input it receives from its
dendritic tree when this input is a random perturbation of a periodic
deterministic signal, driven by an Ornstein-Uhlenbeck process. The neuron
itself is modeled by a variant of the classical Hodgkin-Huxley model. Using the
existence of an accessible point where the weak Hoermander condition holds and
the fact that the coefficients of the system are analytic, we show that the
system is non-degenerate. The existence of a Lyapunov function allows to deduce
the existence of (at most a finite number of) extremal invariant measures for
the process. As a consequence, the complexity of the system is drastically
reduced in comparison with the deterministic system.


title:
Lifespan of smooth solutions for timelike extremal surface equation in
  de Sitter spacetime

abstract:
  In this paper, we study the generalized timelike extremal surface equation in
the de Sitter spacetime, which plays an important role in both mathematics and
physics. Under the assumption of small initial data with compact support, we
investigate the lower bound of lifespan of smooth solutions by weighted energy
estimates.


title: A graph-dynamical interpretation of Kiselman's semigroups

abstract:
  A Sequential Dynamical System (SDS) is a quadruple (\Gamma, S_i,f_i,w)
consisting of a (directed) graph \Gamma=(V,E), each of whose vertices i\in V is
endowed with a finite set state S_i and an update function f_i: \prod_{j, i \to
j} S_j \to S_i --- we call this structure an {\em update system} --- and a word
w in the free monoid over V, specifying the order in which update functions are
to be performed. Each word induces an evolution of the system and in this paper
we are interested in the dynamics monoid, whose elements are all possible
evolutions.
  When \Gamma is a directed acyclic graph, the dynamics monoid of every update
system supported on \Gamma naturally arises as a quotient of the Hecke-Kiselman
monoid associated with \Gamma. In the special case where \Gamma = \Gamma_n is
the complete oriented acyclic graph on n vertices, we exhibit an update system
whose dynamics monoid coincides with Kiselman's semigroup K_n, thus showing
that the defining Hecke-Kiselman relations are optimal in this situation. We
then speculate on how these results may extend to the general acyclic case.


title: H0 Revisited

abstract:
  I reanalyse the Riess et al. (2011, hereafter R11) Cepheid data using the
revised geometric maser distance to NGC 4258 of Humphreys et al. (2013). I
explore different outlier rejection criteria designed to give a reduced
chi-squared of unity and compare the results with the R11 rejection algorithm,
which produces a reduced chi-squared that is substantially less than unity and,
in some cases, to underestimates of the errors on parameters. I show that there
are sub-luminous low metallicity Cepheids in the R11 sample that skew the
global fits of the period-luminosity relation. This has a small but
non-negligible impact on the global fits using NGC 4258 as a distance scale
anchor, but adds a poorly constrained source of systematic error when using the
Large Magellanic Cloud (LMC) as an anchor. I also show that the small Milky Way
(MW) Cepheid sample with accurate parallax measurements leads to a distance to
NGC 4258 that is in tension with the maser distance. I conclude that H0 based
on the NGC 4258 maser distance is H0 = 70.6 +/- 3.3 km/s/Mpc compatible within
1 sigma with the recent determination from Planck for the base six-parameter
LCDM cosmology. If the H-band period-luminosity relation is assumed to be
independent of metallicity and the three distance anchors are combined, I find
H0 = 72.5 +/- 2.5 km/s/Mpc, which differs by 1.9 sigma from the Planck value.
The differences between the Planck results and these estimates of H0 are not
large enough to provide compelling evidence for new physics at this stage.


title:
Pulsed Sagnac polarization-entangled photon source with a PPKTP crystal
  at telecom wavelength

abstract:
  We demonstrate pulsed polarization-entangled photons generated from a
periodically poled $\mathrm{KTiOPO_4}$ (PPKTP) crystal in a Sagnac
interferometer configuration at telecom wavelength. Since the
group-velocity-matching (GVM) condition is satisfied, the intrinsic spectral
purity of the photons is much higher than in the previous scheme at around 800
nm wavelength. The combination of a Sagnac interferometer and the GVM-PPKTP
crystal makes our entangled source compact, stable, highly entangled,
spectrally pure and ultra-bright. The photons were detected by two
superconducting nanowire single photon detectors (SNSPDs) with detection
efficiencies of 70% and 68% at dark counts of less than 1 kcps. We achieved
fidelities of 0.981 $\pm$ 0.0002 for $\left| {\psi ^ -} \right\rangle$ and
0.980 $\pm$ 0.001 for $\left| {\psi ^ +} \right\rangle$ respectively. This
GVM-PPKTP-Sagnac scheme is directly applicable to quantum communication
experiments at telecom wavelength, especially in free space.


title: Entangling unitary gates on distant qubits with ancilla feedback

abstract:
  By using an ancilla qubit as a mediator, two distant qubits can undergo a
non-local entangling unitary operation. This is desirable for when attempting
to scale up or distribute quantum computation by combining fixed static local
sets of qubits with ballistic mediators. Using a model driven by measurements
on the ancilla, it is possible to generate a maximally entangling CZ gate while
only having access to a less entangling gate between the pair qubits and the
ancilla. However this results in a stochastic process of generating control
phase rotation gates where the expected time for success does not correlate
with the entangling power of the connection gate. We explore how one can use
feedback into the preparation and measurement parameters of the ancilla to
speed up the expected time to generate a CZ gate between a pair of separated
qubits and to leverage stronger coupling strengths for faster times.
Surprisingly, by choosing an appropriate strategy, control of a binary discrete
parameter achieves comparable speed up to full continuous control of all
degrees of freedom of the ancilla.


title: Remarks on the Central Limit Theorem for Non-Convex Bodies

abstract:
  In this note, we study possible extensions of the Central Limit Theorem for
non-convex bodies. First, we prove a Berry-Esseen type theorem for a certain
class of unconditional bodies that are not necessarily convex. Then, we
consider a widely-known class of non-convex bodies, the so-called p-convex
bodies, and construct a counter-example for this class.


title: Perturbative analysis of twisted volume reduced theories

abstract:
  We discuss the perturbative expansion of SU(N) Yang-Mills theories defined on
a d-dimensional torus of linear size l with twisted boundary conditions,
generalizing previous results in the literature. For a specific class of twist
tensors depending on a single integer flux value k, we show that perturbative
results to all orders depend on the combination lN^(2/d) and a flux-dependent
angle theta. This implies a new kind of volume independence that holds at
finite N and for fixed values of theta. Our results also provide interesting
information about the possible occurrence of tachyonic instabilities at
one-loop order. We support the prescription that instabilities are avoided, if
the large N limit is taken keeping theta > theta_c, and appropriately scaling
the magnetic flux k with N. Numerical results in 2+1 dimensions provide a test
of how these ideas extend into the non-perturbative regime.


title:
Generalized virtual braid groups, quasi-shuffle product and quantum
  groups

abstract:
  We introduce in this paper the generalized virtual braid group on n strands
GVB_n, generalizing simultaneously the braid groups and their virtual versions.
A Mastumoto-Tits type section lifting shuffles in a symmetric group S_n to the
monoid associated to GVB_n is constructed, which is then applied to
characterize the quantum quasi-shuffle product. A family of representations of
GVB_n is constructed using quantum groups.


title:
A possible resolution of tension between {\it Planck} and Type Ia
  supernova observations

abstract:
  There is an apparent tension between cosmological parameters obtained from
{\it Planck} cosmic microwave background radiation observations and that
derived from the observed magnitude-redshift relation for the type Ia supernova
(SNe Ia). Here, we show that the tension can be alleviated, if we first
calibrate, with the help of the distance-duality relation, the light-curve
fitting parameters in the distance estimation in SNe Ia observations with the
angular diameter distance data of the galaxy clusters and then re-estimate the
distances for the SNe Ia with the corrected fitting parameters. This was used
to explore their cosmological implications in the context of the spatially flat
cosmology. We find a higher value for the matter density parameter, $\Omega_m$,
as compared to that from the original SNLS3, which is in agreement with {\it
Planck} observations at $68.3\%$ confidence. Therefore, the tension between
{\it Planck} measurements and SNe Ia observations regarding $\Omega_m$ can be
effectively alleviated without invoking new physics or resorting to extensions
for the standard concordance model. Moreover, with the absolute magnitude of a
fiducial SNe Ia, $M$, determined first, we obtained a constraint on the Hubble
constant with SNLS3 alone, which is also consistent with {\it Planck}.


title:
Accuracy of Algebraic Fourier Reconstruction for Shifts of Several
  Signals

abstract:
  We consider the problem of "algebraic reconstruction" of linear combinations
of shifts of several known signals $f_1,\ldots,f_k$ from the Fourier samples.
Following \cite{Bat.Sar.Yom2}, for each $j=1,\ldots,k$ we choose sampling set
$S_j$ to be a subset of the common set of zeroes of the Fourier transforms
${\cal F}(f_\ell), \ \ell \ne j$, on which ${\cal F}(f_j)\ne 0$. It was shown
in \cite{Bat.Sar.Yom2} that in this way the reconstruction system is
"decoupled" into $k$ separate systems, each including only one of the signals
$f_j$. The resulting systems are of a "generalized Prony" form.
  However, the sampling sets as above may be non-uniform/not "dense enough" to
allow for a unique reconstruction of the shifts and amplitudes. In the present
paper we study uniqueness and robustness of non-uniform Fourier sampling of
signals as above, investigating sampling of exponential polynomials with purely
imaginary exponents. As the main tool we apply a well-known result in Harmonic
Analysis: the Tur\'an-Nazarov inequality (\cite{Naz}), and its generalization
to discrete sets, obtained in \cite{Fri.Yom}. We illustrate our general
approach with examples, and provide some simulation results.


title: Asymptotic expansions, $L$-values and a new Quantum Modular Form

abstract:
  In 2010 Zagier introduced the notion of a quantum modular form. One of his
first examples was the "strange" function $F(q)$ of Kontsevich. Here we produce
a new example of a quantum modular form by making use of some of Ramanujan's
mock theta functions. Using these functions and their transformation behaviour,
we also compute asymptotic expansions similar to expansions of $F(q)$.


title: Simple Extensions of Polytopes

abstract:
  We introduce the simple extension complexity of a polytope P as the smallest
number of facets of any simple (i.e., non-degenerate in the sense of linear
programming) polytope which can be projected onto P. We devise a combinatorial
method to establish lower bounds on the simple extension complexity and show
for several polytopes that they have large simple extension complexities. These
examples include both the spanning tree and the perfect matching polytopes of
complete graphs, uncapacitated flow polytopes for non-trivially decomposable
directed acyclic graphs, hypersimplices, and random 0/1-polytopes with vertex
numbers within a certain range. On our way to obtain the result on perfect
matching polytopes we generalize a result of Padberg and Rao's on the adjacency
structures of those polytopes. To complement the lower bounding techniques we
characterize in which cases known construction techniques yield simple
extensions.


title:
Classical Heisenberg spins with long-range interactions: Relaxation to
  equilibrium for finite systems

abstract:
  Systems with long-range interactions often relax towards statistical
equilibrium over timescales that diverge with $N$, the number of particles. A
recent work [S. Gupta and D. Mukamel, J. Stat. Mech.: Theory Exp. P03015
(2011)] analyzed a model system comprising $N$ globally coupled classical
Heisenberg spins and evolving under classical spin dynamics. It was numerically
shown to relax to equilibrium over a time that scales superlinearly with $N$.
Here, we present a detailed study of the Lenard-Balescu operator that accounts
at leading order for the finite-$N$ effects driving this relaxation. We
demonstrate that corrections at this order are identically zero, so that
relaxation occurs over a time longer than of order $N$, in agreement with the
reported numerical results.


title: Solar astrometry with Rio Astrolabe and Heliometer

abstract:
  Monitoring the micro-variations of the solar diameter helps to better
understand local and secular trends of solar activity and Earth climate. The
instant measurements with the Reflecting Heliometer of Observatorio Nacional in
Rio de Janeiro have minimized optical and thermal distortion, statistically
reducing air turbulence effects down to 0.01 arcsec. Contrarily to satellites
RHRJ has unlimited lifetime, and it bridges and extends the measures made with
drift-scan timings across altitude circles with 0.1 arcsec rms with Astrolabes.
The Astrolabe in Rio operated from 1998 to 2009 to measure the solar diameter
and the detected variations have statistical significance.


title: Inverses of moment Hermitian matrices

abstract:
  Motivated by [9] we study the existence of the inverse of infinite Hermitian
moment matrices associated with measures with support on the complex plane. We
relate this problem to the asymptotic behaviour of the smallest eigenvalues of
finite sections and we study it from the point of view of infinite transition
matrices associated to the orthogonal polynomials. For Toeplitz matrices we
introduce the notion of weakly asymptotic Toeplitz matrix and we show that,
under certain assumptions, the inverse of a Toeplitz moment matrix is weakly
asymptotic Toeplitz. Such inverses are computed in terms of some limits of the
coefficients of the associated orthogonal polynomials. We finally show that the
asymptotic behaviour of the smallest eigenvalue of a moment Toeplitz matrix
only depends on the absolutely part of the associated measure.


title: Formation of singularities in one-dimensional Chaplygin gas

abstract:
  In this paper we investigate the formation and propagation of singularities
for the system for one-dimensional Chaplygin gas. In particular, under suitable
assumptions we construct a physical solution with a new type of singularities
called "Delta-like" solution for this kind of quasilinear hyperbolic system
with linearly degenerate characteristics. By careful analysis, we study the
behavior of the solution in a neighborhood of a blowup point. The formation of
this new kind of singularities is due to the envelope of the different families
of characteristics instead of the same family of characteristics in the
traditional situation. This shows that the blowup phenomenon of solution for
the system with linearly degenerate characteristics is quite different from the
situation of shock formation for the system with genuinely nonlinear
characteristics. Different initial data can lead to kinds of different
Delta-like singularities: the Delta-like singularity with point-shape and
Delta-like singularity with line-shape.


title: Social Influence and the Collective Dynamics of Opinion Formation

abstract:
  Social influence is the process by which individuals adapt their opinion,
revise their beliefs, or change their behavior as a result of social
interactions with other people. In our strongly interconnected society, social
influence plays a prominent role in many self-organized phenomena such as
herding in cultural markets, the spread of ideas and innovations, and the
amplification of fears during epidemics. Yet, the mechanisms of opinion
formation remain poorly understood, and existing physics-based models lack
systematic empirical validation. Here, we report two controlled experiments
showing how participants answering factual questions revise their initial
judgments after being exposed to the opinion and confidence level of others.
Based on the observation of 59 experimental subjects exposed to peer-opinion
for 15 different items, we draw an influence map that describes the strength of
peer influence during interactions. A simple process model derived from our
observations demonstrates how opinions in a group of interacting people can
converge or split over repeated interactions. In particular, we identify two
major attractors of opinion: (i) the expert effect, induced by the presence of
a highly confident individual in the group, and (ii) the majority effect,
caused by the presence of a critical mass of laypeople sharing similar
opinions. Additional simulations reveal the existence of a tipping point at
which one attractor will dominate over the other, driving collective opinion in
a given direction. These findings have implications for understanding the
mechanisms of public opinion formation and managing conflicting situations in
which self-confident and better informed minorities challenge the views of a
large uninformed majority.


title:
Critical current anisotropy in Nd-1111 single crystals and the infuence
  of neutron irradiation

abstract:
  We report on angle-resolved magnetization measurements on
NdFeAsO$_{0.65}$F$_{0.35}$ (Nd-1111) single crystals. The field dependence of
the critical current density, $J_c$, is non-monotonous in these crystals at all
orientations and temperatures due to the fishtail effect, which strongly
influences the angular dependence of $J_c$. The currents decrease as the field
is tilted from the crystallographic c-axis at low fields, but increase at high
fields. A peak occurs in the angular dependence of $J_c$ at intermediate
fields. The critical currents are significantly enhanced after irradiation with
fast neutrons and the fishtail disappears. The different current anisotropies
at low and high fields, however, persist. We discuss the data in the framework
of the anisotropic scaling approach and propose a transition from dominant
pinning by large defects of low density at low fields to pinning by small
defects of high density at high fields in the pristine crystal. Strong pinning
dominates at all fields after the irradiation, and the angular dependence of
$J_c$ can be described by anisotropic scaling only after an appropriate
extension to this pinning regime.


title:
Characteristics, Bicharacteristics, and Geometric Singularities of
  Solutions of PDEs

abstract:
  Many physical systems are described by partial differential equations (PDEs).
Determinism then requires the Cauchy problem to be well-posed. Even when the
Cauchy problem is well-posed for generic Cauchy data, there may exist
characteristic Cauchy data. Characteristics of PDEs play an important role both
in Mathematics and in Physics. I will review the theory of characteristics and
bicharacteristics of PDEs, with a special emphasis on intrinsic aspects, i.e.,
those aspects which are invariant under general changes of coordinates. After a
basically analytic introduction, I will pass to a modern, geometric point of
view, presenting characteristics within the jet space approach to PDEs. In
particular, I will discuss the relationship between characteristics and
singularities of solutions and observe that: "wave-fronts are characteristic
surfaces and propagate along bicharacteristics". This remark may be understood
as a mathematical formulation of the wave/particle duality in optics and/or
quantum mechanics. The content of the paper reflects the three hour minicourse
that I gave at the XXII International Fall Workshop on Geometry and Physics,
September 2-5, 2013, Evora, Portugal.


title:
Direct formation of millisecond pulsars from rotationally delayed
  accretion-induced collapse of massive white dwarfs

abstract:
  Millisecond pulsars (MSPs) are believed to be old neutron stars, formed via
Type Ib/c core-collapse supernovae, which have subsequently been spun up to
high rotation rates via accretion from a companion star in a highly
circularised low-mass X-ray binary. The recent discoveries of Galactic field
binary MSPs in eccentric orbits, and mass functions compatible with that
expected for helium white dwarf companions, PSR J2234+06 and PSR J1946+3417,
therefore challenge this picture. Here we present a hypothesis for producing
this new class of systems, where the MSPs are formed directly from a
rotationally-delayed accretion-induced collapse of a super-Chandrasekhar mass
white dwarf. We compute the orbital properties of the MSPs formed in such
events and demonstrate that our hypothesis can reproduce the observed
eccentricities, masses and orbital periods of the white dwarfs, as well as
forecasting the pulsar masses and velocities. Finally, we compare this
hypothesis to a triple star scenario.


title:
A study of random resistor-capacitor-diode networks to assess the
  electromagnetic properties of carbon nanotube filled polymers

abstract:
  We determined the frequency dependent effective permittivity of a large
ternary network of randomly positioned resistors, capacitors, and diodes. A
linear circuit analysis of such systems is shown to match the experimental
dielectric response of single-walled carbon nanotube (SWCNT) filled polymers.
This modeling method is able to reproduce the two most important features of
SWCNT filled composites, i.e. the low frequency dispersion and dipolar
relaxation. As a result of the modeling important physical conclusion proved by
the experimental data was done: the low frequency behavior of SWCNT-filled
polymer composites is mostly caused by the fraction of semiconducting SWCNTs.


title:
Structure-dynamic approach in nanoionics. Modeling of ion transport on
  blocking electrode

abstract:
  The work develops the structure-dynamic approach in nanoionics for detailed
description of non-stationary ion-transport processes in irregular potential
relief (direct problem) and interpretation of ionic properties and
characteristics of nanosystems (inverse problem). Theoretical basis of the
structure-dynamic approach, including structural model of interface space
charge region, method of hidden variables and the criterion of smallness of
external influence is presented. The approach is applied for the computational
modeling of ion-transport in the region of ideally polarizable (blocking) solid
electrolyte/electronic conductor (SE/EC) heterojunctions in ac and
galvanostatic modes of external influence.


title:
AMS measurements of cosmogenic and supernova-ejected radionuclides in
  deep-sea sediment cores

abstract:
  Samples of two deep-sea sediment cores from the Indian Ocean are analyzed
with accelerator mass spectrometry (AMS) to search for traces of recent
supernova activity around 2 Myr ago. Here, long-lived radionuclides, which are
synthesized in massive stars and ejected in supernova explosions, namely 26Al,
53Mn and 60Fe, are extracted from the sediment samples. The cosmogenic isotope
10Be, which is mainly produced in the Earths atmosphere, is analyzed for dating
purposes of the marine sediment cores. The first AMS measurement results for
10Be and 26Al are presented, which represent for the first time a detailed
study in the time period of 1.7-3.1 Myr with high time resolution. Our first
results do not support a significant extraterrestrial signal of 26Al above
terrestrial background. However, there is evidence that, like 10Be, 26Al might
be a valuable isotope for dating of deep-sea sediment cores for the past few
million years.


title:
Absolute dimensions of detached eclipsing binaries. III. The
  metallic-lined system YZ Cassiopeiae

abstract:
  The bright binary system YZ Cassiopeiae is a remarkable laboratory for
studying the Am phenomenon. It consists of a metallic-lined A2 star and an F2
dwarf on a circular orbit, which undergo total and annular eclipses. We present
an analysis of 15 published light curves and 42 new high-quality echelle
spectra, resulting in measurements of the masses, radii, effective temperatures
and photospheric chemical abundances of the two stars. The masses and radii are
measured to 0.5% precision: M_A = 2.263 +/- 0.012 Msun, M_B = 1.325 +/- 0.007
Msun, R_A = 2.525 +/- 0.011 Rsun and R_B = 1.331 +/- 0.006 Rsun. We determine
the abundance of 20 elements for the primary star, of which all except scandium
are super-solar by up to 1 dex. The temperature of this star (9520 +/- 120 K)
makes it one of the hottest Am stars. We also measure the abundances of 25
elements for its companion (Teff = 6880 +/- 240 K), finding all to be solar or
slightly above solar. The photospheric abundances of the secondary star should
be representative of the bulk composition of both stars. Theoretical stellar
evolutionary models are unable to match these properties: the masses, radii and
temperatures imply a half-solar chemical composition (Z = 0.009 +/- 0.003) and
an age of 490-550 Myr. YZ Cas therefore presents a challenge to stellar
evolutionary theory.


title: Subsiding routing misbehavior in MANET using "Mirror Model"

abstract:
  Noncooperation or failure to work together is a big challenge that surely
degrades the performance and reliability of Mobile Adhoc Networks. In MANETs,
nodes have dual responsibilities of forwarding and routing, that's why it needs
unison with nodes. To sort out non-cooperation a real life behavior should be
implemented, so that misbehavior is nullified. In this paper, we present the
"Mirror Model" that strictly enforces cooperation due to its punishment
strategy. Node's behavior is watched by its neighbors in PON mode, to update
the NPF, NPRF values for a threshold time. After the expiry of the threshold
time each node calculates the PFR and broadcasts its neighbors. Similarly all
neighbors broadcasted PFR is received and processed by the node to define the
'G' and 'BP' values. The G value is used to isolate selfish nodes from the
routing paths and BP denotes the amount of packets to be dropped by an honest
node against a selfish node in spite of its misbehavior/packet drops.
Cooperation within the neighbors, certainly result in subsiding misbehavior of
selfish nodes, therein enhancing cooperation of the whole MANET. This model
ensures honesty and reliability in MANET because it does not eliminate a node,
but it behaves in the same way as the node behaved. Therefore, it justifies its
name, after all mirrors reflects the same. We have implemented the model in
"GloMoSim" on top of the DSR protocol, resulting its effectiveness, as compared
to the DSR protocol when the network is misconducting for its selfish needs.


title: Optical observations of SN 2011fe

abstract:
  We present UBVRI photometry of the supernova 2011fe in M101, obtained in the
interval of 1-652 days after its discovery, as well as one spectrum, taken 105
days after the brightness maximum in the B band. We derived parameters of the
light curves, constructed the colour curves and a "quasi-bolometric" light
curve. The light curves, colour evolution and spectrum of the object indicate
that SN 2011fe belongs to the "normal" subset of type Ia supernovae. It is
practically identical to a well-studied "normal" SN Ia 2003du.


title: A New Algorithm for Distributed Nonparametric Sequential Detection

abstract:
  We consider nonparametric sequential hypothesis testing problem when the
distribution under the null hypothesis is fully known but the alternate
hypothesis corresponds to some other unknown distribution with some loose
constraints. We propose a simple algorithm to address the problem. These
problems are primarily motivated from wireless sensor networks and spectrum
sensing in Cognitive Radios. A decentralized version utilizing spatial
diversity is also proposed. Its performance is analysed and asymptotic
properties are proved. The simulated and analysed performance of the algorithm
is compared with an earlier algorithm addressing the same problem with similar
assumptions. We also modify the algorithm for optimizing performance when
information about the prior probabilities of occurrence of the two hypotheses
are known.


title: The H.E.S.S. central data acquisition system

abstract:
  The High Energy Stereoscopic System (H.E.S.S.) is a system of Imaging
Atmospheric Cherenkov Telescopes (IACTs) located in the Khomas Highland in
Namibia. It measures cosmic gamma rays of very high energies (VHE; >100 GeV)
using the Earth's atmosphere as a calorimeter. The H.E.S.S. Array entered Phase
II in September 2012 with the inauguration of a fifth telescope that is larger
and more complex than the other four. This paper will give an overview of the
current H.E.S.S. central data acquisition (DAQ) system with particular emphasis
on the upgrades made to integrate the fifth telescope into the array. At first,
the various requirements for the central DAQ are discussed then the general
design principles employed to fulfil these requirements are described. Finally,
the performance, stability and reliability of the H.E.S.S. central DAQ are
presented. One of the major accomplishments is that less than 0.8% of
observation time has been lost due to central DAQ problems since 2009.


title: Quantum Mechanics \`a la Langevin and Supersymmetry

abstract:
  We study quantum mechanics in the stochastic formulation, using the
functional integral approach. The noise term enters the classical action as a
local contribution of anticommuting fields. The partition function is not
invariant under ${\mathcal N}=1$ SUSY, but can be obtained from a, manifestly,
supersymmetric expression, upon fixing a local fermionic symmetry, called
$\kappa-$symmetry. The kinetic term for the fermions is a total derivative and
can contribute only on the boundaries. We define combinations that scale
appropriately, as the lattice spacing is taken to zero and the lattice size to
infinity and provide evidence, by numerical simulations, that the correlation
functions of the auxiliary field do satisfy Wick's theorem. We show, in
particular, that simulations can be carried out using a purely bosonic action.
  The physical import is that the classical trajectory, $\phi(\tau)$, becomes a
(chiral) superfield, $(\phi(\tau),\psi_{\alpha}(\tau),F(\tau))$, when quantum
fluctuations are taken into account.


title:
Algebraic characterization of quasi-isometric spaces via the Higson
  compactification

abstract:
  The purpose of this article is to characterize the quasi-isometry type of a
proper metric space via the Banach algebra of Higson functions on it.


title:
Imaging blood cells through scattering biological tissue using speckle
  scanning microscopy

abstract:
  Using optical speckle scanning microscopy [1], we demonstrate that clear
images of multiple cells can be obtained through biological scattering tissue,
with subcellular resolution and good image quality, as long as the size of the
imaging target is smaller than the scanning range of the illuminating speckle
pattern.


title: Equicontinuous foliated spaces

abstract:
  Some properties of Riemannian foliations on closed manifolds are generalized
to compact equicontinuous foliated spaces. For instance, it is proved that all
holonomy covers of the leaves are quasi-isometric to each other.


title: Topological description of Riemannian foliations with dense leaves

abstract:
  A transitive compact foliated space is shown to be a Riemannian foliation if
and only if it is locally connected, finite dimensional, strongly
equicontinuous and quasi-analytic, and the closure of its holonomy pseudogroup
is quasi-analytic.


title:
High-dimensional learning of linear causal networks via inverse
  covariance estimation

abstract:
  We establish a new framework for statistical estimation of directed acyclic
graphs (DAGs) when data are generated from a linear, possibly non-Gaussian
structural equation model. Our framework consists of two parts: (1) inferring
the moralized graph from the support of the inverse covariance matrix; and (2)
selecting the best-scoring graph amongst DAGs that are consistent with the
moralized graph. We show that when the error variances are known or estimated
to close enough precision, the true DAG is the unique minimizer of the score
computed using the reweighted squared l_2-loss. Our population-level results
have implications for the identifiability of linear SEMs when the error
covariances are specified up to a constant multiple. On the statistical side,
we establish rigorous conditions for high-dimensional consistency of our
two-part algorithm, defined in terms of a "gap" between the true DAG and the
next best candidate. Finally, we demonstrate that dynamic programming may be
used to select the optimal DAG in linear time when the treewidth of the
moralized graph is bounded.


title:
Asymptotically Exact Scenario of Strong-Disorder Criticality in
  One-Dimensional Superfluids

abstract:
  We present a controlled rare-weak-link theory of the superfluid-to-Bose/Mott
glass transition in one-dimensional disordered systems. The transition has
Kosterlitz-Thouless critical properties but may occur at an arbitrary large
value of the Luttinger parameter $K$. In contrast to the scenario by Altman
{\it et al.} [Phys. Rev. B {\bf 81}, 174528 (2010)], the hydrodynamic
description is valid under the correlation radius and defines criticality via
the renormalization of microscopically weak links, along the lines of Kane and
Fisher [Phys. Rev. Lett. {\bf 68}, 1220 (1992)]. The hallmark of the theory is
the relation $K^{(c)}=1/\zeta$ between the critical value of the Luttinger
parameter at macroscopic scales and the microscopic (irrenormalizable) exponent
$\zeta$ describing the scaling $\propto 1/N^{1-\zeta}$ for the strength of the
weakest link among the $N/L \gg 1$ disorder realizations in a system of fixed
mesoscopic size $L$.


title:
Fundamental Limits of Online and Distributed Algorithms for Statistical
  Learning and Estimation

abstract:
  Many machine learning approaches are characterized by information constraints
on how they interact with the training data. These include memory and
sequential access constraints (e.g. fast first-order methods to solve
stochastic optimization problems); communication constraints (e.g. distributed
learning); partial access to the underlying data (e.g. missing features and
multi-armed bandits) and more. However, currently we have little understanding
how such information constraints fundamentally affect our performance,
independent of the learning problem semantics. For example, are there learning
problems where any algorithm which has small memory footprint (or can use any
bounded number of bits from each example, or has certain communication
constraints) will perform worse than what is possible without such constraints?
In this paper, we describe how a single set of results implies positive answers
to the above, for several different settings.


title:
Bounding quantum theory with the exclusivity principle in a two-city
  experiment

abstract:
  Why do correlations between the results of measurements performed on physical
systems violate Bell and non-contextuality inequalities up to some specific
limits? The answer may follow from the observation that in quantum theory,
unlike in other theories, whenever there is an experiment to measure $A$
simultaneously with $B$, another to measure $B$ with $C$, and another to
measure $A$ with $C$, there is always an experiment to measure all of them
simultaneously. This property implies that quantum theory satisfies a seemingly
irrelevant restriction called the exclusivity (E) principle which,
surprisingly, explains the set of quantum correlations in some fundamental
scenarios. An open problem is whether the E principle explains the maximum
quantum violation of the Bell-CHSH inequality. Here we show experimentally that
the E principle imposes an upper bound to the violation of the Bell-CHSH
inequality that matches the maximum predicted by quantum theory. For that, we
use the result of an independent experiment testing a specific
non-contextuality inequality. We perform both experiments: the Bell-CHSH
inequality experiment on polarization entangled states of pairs of photons in
Stockholm and, to demonstrate independence, the non-contextuality inequality
experiment on single photons' orbital angular momentum states in Rome. The
observed results provide the first experimental evidence that the E principle
determines the limits of quantum correlations and prove that hypothetical
super-quantum violations for either experiment would violate the E principle.
This supports the conclusion that the E principle captures a fundamental
limitation of nature. If this is true, much of quantum theory trivially follow
from merely taking the E principle to be a fundamental truth, and various
information-theoretic postulates are also simplified and/or strengthened.


title: Status and prospects for the LHCb upgrade

abstract:
  High-precision measurements performed by the LHCb collaboration have opened a
new era in charm physics. Several crucial measurements, particularly in
spectroscopy, rare decays and CP violation, can benefit from the increased
statistical power of an upgraded LHCb detector. The upgrade of LHCb detector,
its software infrastructure, and the impact on charm physics are discussed in
detail.


title:
Higgs Boson Mass and Complex Snuetrino Dark Matter in the Supersymmetric
  Inverse Seesaw Models

abstract:
  The discovery of a relatively heavy Standard Model (SM) -like Higgs boson
challenges naturalness of the minimal supersymmetric standard model (MSSM) from
both Higgs and dark matter (DM) sectors. We study these two aspects in the MSSM
extended by the low-scale inverse seesaw mechanism. Firstly, it admits a
sizable radiative correction on the Higgs boson mass m_h, up to \sim 4 GeV in
the case of an IR-fixed point of the coupling Y_\nu LH_u\nu^c and a large
sneutrino mixing. Secondly, the lightest sneutrino, highly complex as expected,
is a viable thermal DM candidate. Owing to the correct relic density and
XENON100, two cases survive: a Higgs-portal complex DM with mass lying around
the Higgs pole or above $W$ threshold, and a coannihilating DM with slim
prospect of detection. Given an extra family of sneutrinos, both scenarios
naturally work when we attempt to suppress the DM left-handed sneutrino
component, confronting with enhancing m_h.


title: A quantification of hydrodynamical effects on protoplanetary dust growth

abstract:
  Context. The growth process of dust particles in protoplanetary disks can be
modeled via numerical dust coagulation codes. In this approach, physical
effects that dominate the dust growth process often must be implemented in a
parameterized form. Due to a lack of these parameterizations, existing studies
of dust coagulation have ignored the effects a hydrodynamical gas flow can have
on grain growth, even though it is often argued that the flow could
significantly contribute either positively or negatively to the growth process.
  Aims. We intend to provide a quantification of hydrodynamical effects on the
growth of dust particles, such that these effects can be parameterized and
implemented in a dust coagulation code.
  Methods. We numerically integrate the trajectories of small dust particles in
the flow of disk gas around a proto-planetesimal, sampling a large parameter
space in proto-planetesimal radii, headwind velocities, and dust stopping
times.
  Results. The gas flow deflects most particles away from the
proto-planetesimal, such that its effective collisional cross section, and
therefore the mass accretion rate, is reduced. The gas flow however also
reduces the impact velocity of small dust particles onto a proto-planetesimal.
This can be beneficial for its growth, since large impact velocities are known
to lead to erosion. We also demonstrate why such a gas flow does not return
collisional debris to the surface of a proto-planetesimal.
  Conclusions. We predict that a laminar hydrodynamical flow around a
proto-planetesimal will have a significant effect on its growth. However, we
cannot easily predict which result, the reduction of the impact velocity or the
sweep-up cross section, will be more important. Therefore, we provide
parameterizations ready for implementation into a dust coagulation code.


title:
A study on subarcsecond scales of the ammonia and continuum emission
  toward the G16.59-0.05 high-mass star-forming region

abstract:
  We wish to investigate the structure, velocity field, and stellar content of
the G16.59-0.05 high-mass star-forming region, where previous studies have
established the presence of two almost perpendicular (NE-SW and SE-NW), massive
outflows, and a rotating disk traced by methanol maser emission. We performed
Very Large Array observations of the radio continuum and ammonia line emission,
complemented by COMICS/Subaru and Hi-GAL/Herschel images in the mid- and
far-infrared (IR). Our centimeter continuum maps reveal a collimated radio jet
that is oriented E-W and centered on the methanol maser disk, placed at the SE
border of a compact molecular core. The spectral index of the jet is negative,
indicating non-thermal emission over most of the jet, except the peak close to
the maser disk, where thermal free-free emission is observed. We find that the
ammonia emission presents a bipolar structure consistent (on a smaller scale)
in direction and velocity with that of the NE-SW bipolar outflow detected in
previous CO observations. After analyzing our previous N2H+(1-0) observations
again, we conclude that two scenarios are possible. In one case both the radio
jet and the ammonia emission would trace the root of the large-scale CO bipolar
outflow. The different orientation of the jet and the ammonia flow could be
explained by precession and/or a non-isotropic density distribution around the
star. In the other case, the N2H+(1-0) and ammonia bipolarity is interpreted as
two overlapping clumps moving with different velocities along the line of
sight. The ammonia gas also seems to undergo rotation consistent with the maser
disk. Our IR images complemented by archival data allow us to derive a
bolometric luminosity of about 10^4 L_sun and to conclude that most of the
luminosity is due to the young stellar object associated with the maser disk.


title:
Scalar products in models with GL(3) trigonometric R-matrix. Highest
  coefficient

abstract:
  We study quantum integrable models with GL(3) trigonometric R-matrix solvable
by the nested algebraic Bethe ansatz. Scalar products of Bethe vectors in such
models can be expressed in terms of a bilinear combination of the highest
coefficients. We show that in the models with GL(3) trigonometric R-matrix
there exist two different highest coefficients. We obtain various
representations for them in terms of sums over partitions. We also prove
several important properties of the highest coefficients, which are necessary
for the evaluation of the scalar products.


title:
Living on the edge : ground-state selection in quantum spin-ice
  pyrochlores

abstract:
  The search for new quantum phases, especially in frustrated magnets, is
central to modern condensed matter physics. One of the most promising places to
look is in rare-earth pyrochlore magnets with highly-anisotropic exchange
interactions, materials closely related to the spin ices Ho2Ti2O7 and Dy2Ti2O7.
Here we establish a general theory of magnetic order in these materials. We
find that many of their most interesting properties can be traced back to the
accidental degeneracies where phases with different symmetry meet. These
include the ordered ground state selection by fluctuations in Er2Ti2O7, the
dimensional-reduction observed in Yb2Ti2O7, and the absence of magnetic order
in Er2Sn2O7.


title:
Quasi-particle spectra, absorption spectra, and excitonic properties of
  sodium iodide and strontium iodide from many-body perturbation theory

abstract:
  We investigate the basic quantum mechanical processes behind non-proportional
response of scintillators to incident radiation responsible for reduced
resolution. For this purpose, we conduct a comparative first principles study
of quasiparticle spectra on the basis of the $G_0W_0$ approximation as well as
absorption spectra and excitonic properties by solving the Bethe-Salpeter
equation for two important systems, NaI and SrI$_2$. The former is a standard
scintillator material with well-documented non-proportionality while the latter
has recently been found to exhibit a very proportional response. We predict
band gaps for NaI and SrI$_2$ of 5.5 and 5.2 eV, respectively, in good
agreement with experiment. Furthermore, we obtain binding energies for the
groundstate excitons of 216 meV for NaI and 195$\pm$25 meV for SrI$_2$. We
analyze the degree of exciton anisotropy and spatial extent by means of a
coarse-grained electron-hole pair-correlation function. Thereby, it is shown
that the excitons in NaI differ strongly from those in SrI$_2$ in terms of
structure and symmetry, even if their binding energies are similar.
Furthermore, we show that quite unexpectedly the spatial extents of the highly
anisotropic low-energy excitons in SrI$_2$ in fact exceed those in NaI by a
factor of two to three in terms of the full width at half maxima of the
electron-hole pair-correlation function.


title:
Electric field gradient wave (EFGW) in iron-based superconductor
  Ba(0.6)K(0.4)Fe2As2 studied by M\"ossbauer spectroscopy

abstract:
  The optimally doped 122 iron-based superconductor Ba(0.6)K(0.4)Fe2As2 has
been studied by 57Fe Moessbauer spectroscopy versus temperature ranging from
4.2 K till 300 K with particular attention paid to the superconducting
transition around 38 K. The spectra do not contain magnetic components and they
exhibit quasi-continuous distribution of quadrupole split doublets. A
distribution follows the electric field gradient (EFG) spatial modulation
(wave) - EFGW. The EFGW is accompanied by some charge density wave (CDW) having
about an order of magnitude lesser influence on the spectrum. The EFGW could be
modeled as widely separated narrow sheets with the EFG increasing from small
till maximum value almost linearly and subsequently dropping back to the
original value in a similar fashion - across the sheet. One encounters very
small and almost constant EFG between sheets. The EFGW shape and amplitude as
well as the amplitude of CDW are strongly affected by a superconducting
transition. All modulations are damped significantly at transition (38 K) and
recover at a temperature being about 14 K lower. The maximum quadrupole
splitting at 4.2 K amounts to about 2.1 mm/s, while the dispersion of CDW seen
on the iron nuclei could be estimated far away from the superconducting gap
opening and at low temperature as 0.5 el./a.u.^3. It drops to about 0.3
el./a.u.^3 just below transition to the superconducting state.


title: Light production metrics of radiation sources

abstract:
  Light production by a radiation source is evaluated and reviewed as an
important concept of physics from the Black-Body point of view. The mechanical
equivalent of the lumen, the unit of perceived light, is explained and
evaluated using radiation physics arguments. The existence of an upper limit of
luminous efficacy is illustrated for various sources and implications are
highlighted.


title:
Shower development of particles with momenta from 1 to 10 GeV in the
  CALICE Scintillator-Tungsten HCAL

abstract:
  Lepton colliders are considered as options to complement and to extend the
physics programme at the Large Hadron Collider. The Compact Linear Collider
(CLIC) is an $e^+e^-$ collider under development aiming at centre-of-mass
energies of up to 3 TeV. For experiments at CLIC, a hadron sampling calorimeter
with tungsten absorber is proposed. Such a calorimeter provides sufficient
depth to contain high-energy showers, while allowing a compact size for the
surrounding solenoid.
  A fine-grained calorimeter prototype with tungsten absorber plates and
scintillator tiles read out by silicon photomultipliers was built and exposed
to particle beams at CERN. Results obtained with electrons, pions and protons
of momenta up to 10 GeV are presented in terms of energy resolution and shower
shape studies. The results are compared with several GEANT4 simulation models
in order to assess the reliability of the Monte Carlo predictions relevant for
a future experiment at CLIC.


title: Free by cyclic groups are large

abstract:
  If F is a free group of finite rank at least two then any group of the form F
by Z is large. In this short note we show how this statement follows by
combining a very recent theorem of Hagen and Wise (using work of Agol and of
Wise) with earlier results of the author.


title: Spectrum and entanglement of phonons in quantum fluids of light

abstract:
  We study the quantum state of phonons propagating on top of a fluid of light
coherently generated in a planar microcavity device by a quasi-resonant
incident laser beam. In the steady-state under a monochromatic pump, because of
the finite radiative lifetime of photons, a sizable incoherent population of
low frequency phonons is predicted to appear. Their mean occupation number
differs from a Planck distribution and is independent on the photon lifetime.
When the photon fluid is subjected to a sudden change of its parameters,
additional phonon pairs are created in the fluid with remarkable two-mode
squeezing and entanglement properties. Schemes to assess non-separability of
the phonon state from measurements of the correlation functions of the emitted
light are discussed.


title:
Demographic and Structural Characteristics to Rationalize Link Formation
  in Online Social Networks

abstract:
  Recent years have seen tremendous growth of many online social networks such
as Facebook, LinkedIn and MySpace. People connect to each other through these
networks forming large social communities providing researchers rich datasets
to understand, model and predict social interactions and behaviors. New
contacts in these networks can be formed either due to an individual's
demographic profile such as age group, gender, geographic location or due to
network's structural dynamics such as triadic closure and preferential
attachment, or a combination of both demographic and structural
characteristics.
  A number of network generation models have been proposed in the last decade
to explain the structure, evolution and processes taking place in different
types of networks, and notably social networks. Network generation models
studied in the literature primarily consider structural properties, and in some
cases an individual's demographic profile in the formation of new social
contacts. These models do not present a mechanism to combine both structural
and demographic characteristics for the formation of new links. In this paper,
we propose a new network generation algorithm which incorporates both these
characteristics to model growth of a network.We use different publicly
available Facebook datasets as benchmarks to demonstrate the correctness of the
proposed network generation model.


title: Topology beyond the horizon: how far can it be probed?

abstract:
  The standard cosmological model does not determine the spatial topology of
the universe. This article revisits the signature of a non-trivial topology on
the properties of the cosmic microwave background anisotropies. We show that
the correlation function of the coefficients of the expansion of the
temperature and polarization anisotropies in spherical harmonics, encodes a
topological signature that can be used to distinguish a multi-connected space
from an infinite space on sizes larger than the last scattering surface. The
effect of the instrumental noise and of a galactic cut are estimated. We thus
establish boundaries for the size of the biggest torus dintinguisable with
temperature and polarization CMB data. We also describe the imprint of the
spatial topology on the 3-point function and on non-Gaussianity.


title: Survival of New Physics: An Anomaly-free Neutral Gauge Boson at the LHC

abstract:
  An anomaly-free $U(1)'$ effective Lagrangian as the most common new physics
beyond the standard model is proposed to survey the maximal parameter space
constrained by electroweak precise measurements at the LEP and direct detection
in dilepton decay channel at the LHC at $\sqrt{s}=7$ TeV. By the global fit of
effective couplings of $Z$ boson to the SM fermions,
$\Delta_{11},\Delta_{21},g_2\Delta_{31}$ related to mixings and $r$ related to
$U(1)'$ charge assignment are bounded. The allowed areas are plotted in the not
only $r$-$g_2$ but also $m_{Z'}$-$g_2$ planes, which show that a sub-TeV $Z'$
is still permissible as long as the coupling $g_2\sim 0.01$. The results
provides a prime requirement to an extra $U(1)'$ gauge boson and hinds the
direction of possible new physics beyond the standard model. The possible
signal in dilepton decay channel at LHC at $\sqrt{s}=14$ TeV is also provided.


title: Morphisms between complete Riemannian pseudogroups

abstract:
  We introduce the concept of morphism of pseudogroups generalizing the
\'etal\'e morphisms of Haefliger. With our definition, any continuous foliated
map induces a morphism between the corresponding holonomy pseudogroups. The
main theorem states that any morphism between complete Riemannian pseudogroups
is complete, has a closure and its maps are \cinf\ along the orbit closures.
Here, completeness and closure are versions for morphisms of concepts
introduced by Haefliger for pseudogroups. This result is applied to approximate
foliated maps by smooth ones in the case of transversely complete Riemannian
foliations, yielding the foliated homotopy invariance of their spectral
sequence. This generalizes the topological invariance of their basic
cohomology, shown by El Kacimi-Nicolau. A different proof of the spectral
sequence invariance was also given by the second author.


title:
Axisymmetric critical points of a nonlocal isoperimetric problem on the
  two-sphere

abstract:
  On the two dimensional sphere, we consider axisymmetric critical points of an
isoperimetric problem perturbed by a long-range interaction term. When the
parameter controlling the nonlocal term is sufficiently large, we prove the
existence of a local minimizer with arbitrary many interfaces in the
axisymmetric class of admissible functions. These local minimizers in this
restricted class are shown to be critical points in the broader sense (i.e.,
with respect to all perturbations). We then explore the rigidity, due to
curvature effects, in the criticality condition via several quantitative
results regarding the axisymmetric critical points.


title: Pion electromagnetic form factor from full lattice QCD

abstract:
  We present preliminary results from the first calculation of the pion
electromagnetic form factor at physical light quark masses. This form factor
parameterises the deviations from the behaviour of a point-like particle when a
photon hits the pion. These deviations result from the internal structure of
the pion and can thus be calculated in QCD. We use three sets (different
lattice spacings) of n_f=2+1+1 lattice configurations generated by the MILC
collaboration. The Highly Improved Staggered Quark formalism (HISQ) is used for
all of the sea and valence quarks. Using lattice configurations with u/d quark
masses very close to the physical value is an advantage, as we avoid the chiral
extrapolation. We study the shape of the vector (f_+) form factor in the q^2
range from 0 to -0.12 GeV^2 and extract the mean square radius, <r^2_v>. The
shape of the vector form factor and the resulting radius is compared with
experiment.


title:
Expansions for a fundamental solution of Laplace's equation on ${\mathbb
  R^3}$ in 5-cyclidic harmonics

abstract:
  We derive eigenfunction expansions for a fundamental solution of Laplace's
equation in three-dimensional Euclidean space in 5-cyclidic coordinates. There
are three such expansions in terms of internal and external 5-cyclidic
harmonics of first, second and third kind. The internal and external 5-cyclidic
harmonics are expressed by solutions of a Fuchsian differential equation with
five regular singular points.


title:
Model predictive control of voltage profiles in MV networks with
  distributed generation

abstract:
  The Model Predictive Control (MPC) approach is used in this paper to control
the voltage profiles in MV networks with distributed generation. The proposed
algorithm lies at the intermediate level of a three-layer hierarchical
structure. At the upper level a static Optimal Power Flow (OPF) manager
computes the required voltage profiles to be transmitted to the MPC level,
while at the lower level local Automatic Voltage Regulators (AVR), one for each
Distributed Generator (DG), track the reactive power reference values computed
by MPC. The control algorithm is based on an impulse response model of the
system, easily obtained by means of a detailed simulator of the network, and
allows to cope with constraints on the voltage profiles and/or on the reactive
power flows along the network. If these constraints cannot be satisfied by
acting on the available DGs, the algorithm acts on the On-Load Tap Changing
(OLTC) transformer. A radial rural network with two feeders, eight DGs, and
thirty-one loads is used as case study. The model of the network is implemented
in DIgSILENT PowerFactory, while the control algorithm runs in Matlab. A number
of simulation results is reported to witness the main characteristics and
limitations of the proposed approach.


title:
Specific heat of Ca$_{0.32}$Na$_{0.68}$Fe$_2$As$_2$ single crystals:
  unconventional s$_\pm$ multi-band superconductivity with intermediate
  repulsive interband coupling and sizable attractive intraband couplings

abstract:
  We report a low-temperature specific heat study of high-quality single
crystals of the heavily hole doped superconductor
Ca$_{0.32}$Na$_{0.68}$Fe$_2$As$_2$. This compound exhibits bulk
superconductivity with a transition temperature $T_c \approx 34$\,K, which is
evident from the magnetization, transport, and specific heat measurements. The
zero field data manifests a significant electronic specific heat in the normal
state with a Sommerfeld coefficient $\gamma \approx 53$ mJ/mol K$^{2}$. Using a
multi-band Eliashberg analysis, we demonstrate that the dependence of the zero
field specific heat in the superconducting state is well described by a
three-band model with an unconventional s$_\pm$ pairing symmetry and gap
magnitudes $\Delta_i$ of approximately 2.35, 7.48, and -7.50 meV. Our analysis
indicates a non-negligible attractive intraband coupling,which contributes
significantly to the relatively high value of $T_c$. The Fermi surface averaged
repulsive and attractive coupling strengths are of comparable size and outside
the strong coupling limit frequently adopted for describing high-$T_c$ iron
pnictide superconductors. We further infer a total mass renormalization of the
order of five, including the effects of correlations and electron-boson
interactions.


title: On the first secondary invariant of Molino's central sheaf

abstract:
  For a Riemannian foliation on a closed manifold, the first secondary
invariant of Molino's central sheaf is an obstruction to tautness. Another
obstruction is the class defined by the basic component of the mean curvature
with respect to some metric. Both obstructions are proved to be the same up to
a constant, and other geometric properties are also proved to be equivalent to
tautness.


title: The dimension of the leafwise reduced cohomology

abstract:
  Geometric conditions are given so that the leafwise reduced cohomology is of
infinite dimension, specially for foliations with dense leaves on closed
manifolds. The main new definition involved is the intersection number of
subfoliations with "appropriate coefficients". The leafwise reduced cohomology
is also described for homogeneous foliations with dense leaves on closed
nilmanifolds.


title:
Perturbative renormalization of staggered fermion operators with stout
  improvement: Application to the magnetic susceptibility of QCD

abstract:
  We calculate the fermion propagator and the quark-antiquark Green's functions
for a complete set of ultralocal fermion bilinears, ${{\cal O}_\Gamma}$
[$\Gamma$: scalar (S), pseudoscalar (P), vector (V), axial (A) and tensor (T)],
using perturbation theory up to one-loop and to lowest order in the lattice
spacing. We employ the staggered action for fermions and the Symanzik Improved
action for gluons. From our calculations we determine the renormalization
functions for the quark field and for all ultralocal taste-singlet bilinear
operators. The novel aspect of our calculations is that the gluon links which
appear both in the fermion action and in the definition of the bilinears have
been improved by applying a stout smearing procedure up to two times,
iteratively. Compared to most other improved formulations of staggered
fermions, the above action, as well as the HISQ action, lead to smaller taste
violating effects. The renormalization functions are presented in the RI$'$
scheme; the dependence on all stout parameters, as well as on the coupling
constant, the number of colors, the lattice spacing, the gauge fixing parameter
and the renormalization scale, is shown explicitly.
  We apply our results to a nonperturbative study of the magnetic
susceptibility of QCD at zero and finite temperature. In particular, we
evaluate the "tensor coefficient", $\tau$, which is relevant to the anomalous
magnetic moment of the muon.


title: Generalized Topological Transition Matrix

abstract:
  This article represents a major step in the unification of the theory of
algebraic, topological and singular transition matrices by introducing a
definition which is a generalization that encompasses all of the previous
three. When this more general transition matrix satisfies the additional
requirement that it covers flow-defined Conley-index isomorphisms, one proves
algebraic and connection-existence properties. These general transition
matrices with this covering property are referred to as generalized topological
transition matrices and are used to consider connecting orbits of Morse-Smale
flows without periodic orbits, as well as those in a continuation associated to
a dynamical spectral sequence.


title: On a model of forced axisymmetric flows

abstract:
  In this work, we consider a model of forced axisymmetric flows which is
derived from the inviscid Boussinesq equations. What makes these equations
unusual is the boundary conditions they are expected to satisfy and the fact
that the boundary is part of the unknown. We show that these flows give rise to
an unusual Monge-Ampere equations for which we prove the existence and the
uniqueness of a variational solution. We take advantage of these Monge-Ampere
equations and construct a solution to the model.


title:
On the congruence $\sum_{j=1}^{n-1} j^{k(n-1)} \equiv -1 \pmod n $.
  k-strong Giuga and k-Carmichael numbers

abstract:
  In this work we consider the congruence $\sum_{j=1}^{n-1} j^{k(n-1)} \equiv
-1 \pmod n$ for each $k \in \mathbb{N}$, thus extending Giuga's ideas for
$k=1$. In particular, it is proved that a pair $(n,k)\in \mathbb{N}^2$
satisfies this congruence if and only if $n$ is prime or a Giuga Number and
$\lambda(n) \mid k(n-1)$. In passing, we establish new characterizations of
Giuga numbers and we study some properties of the numbers $n$ satisfying
$\lambda(n) \mid k(n-1)$.


title:
First Workshop on Sustainable Software for Science: Practice and
  Experiences (WSSSPE): Submission and Peer-Review Process, and Results

abstract:
  This technical report discusses the submission and peer-review process used
by the First Workshop on on Sustainable Software for Science: Practice and
Experiences (WSSSPE) and the results of that process. It is intended to record
both this alternative model as well as the papers associated with the workshop
that resulted from that process.


title: Plots and Their Applications - Part I: Foundations

abstract:
  The primary goal of this paper is to abstract notions, results and
constructions from the theory of categories to the broader setting of plots.
Loosely speaking, a plot can be thought of as a non-associative non-unital
category with a "relaxed" composition law: Besides categories, this includes as
a special case graphs and neocategories in the sense of Ehresmann, Gabriel's
quivers, Mitchell's semicategories, and composition graphs, precategories and
semicategories in the sense of Schr\"oder. Among other things, we formulate an
"identity-free" definition of isomorphisms, equivalences, and limits, for which
we introduce regular representations, punctors, $\mathcal M$-connections, and
$\mathcal M$-factorizations. Part of the material will be used in subsequent
work to lay the foundation for an abstract theory of "normed structures"
serving as a unifying framework for the development of fundamental aspects of
the theory of normed spaces, normed groups, etc., on the one hand, and measure
spaces, perhaps surprisingly, on the other.


title:
Uniformisation locale des sch\'emas quasi-excellents de
  caract\'eristique nulle

abstract:
  We prove an embedded local uniformization theroem for a valuation centered on
a point of a quasi-excellent scheme of characteristic zero. The proof reduces
to valuations of rank 1 and consists in desingularizing the ideal formed by the
elements of infinite value and monomializing the key polynomials. We then prove
a monomialization theorem valid in all characteristic under certain conditions,
including that of non-existence of limit key polynomials, a condition that is
always satified in characteristic zero.


title: $R$-transforms for Sobolev $H^2$-metrics on spaces of plane curves

abstract:
  We consider spaces of smooth immersed plane curves (modulo translations
and/or rotations), equipped with reparameterization invariant weak Riemannian
metrics involving second derivatives. This includes the full $H^2$-metric
without zero order terms. We find isometries (called $R$-transforms) from some
of these spaces into function spaces with simpler weak Riemannian metrics, and
we use this to give explicit formulas for geodesics, geodesic distances, and
sectional curvatures. We also show how to utilise the isometries to compute
geodesics numerically.


title: A new information dimension of complex networks

abstract:
  The fractal and self-similarity properties are revealed in many real complex
networks. However, the classical information dimension of complex networks is
not practical for real complex networks. In this paper, a new information
dimension to characterize the dimension of complex networks is proposed. The
difference of information for each box in the box-covering algorithm of complex
networks is considered by this measure. The proposed method is applied to
calculate the fractal dimensions of some real networks. Our results show that
the proposed method is efficient for fractal dimension of complex networks.


title: New version of $q$-deformed supersymmetric quantum mechanics

abstract:
  A new version of the q-deformed supersymmetric quantum mechanics (q-SQM),
which is inspired by the Tamm--Dankoff-type (TD-type) deformation of quantum
harmonic oscillator, is constructed. The obtained algebra of q-SQM is similar
to that in Spiridonov's approach. However, within our version of q-SQM, the
ground state found explicitly in the special case of superpotential yiealding
q-superoscillator turns out to be non-Gaussian and takes the form of special
(TD-type) q-deformed Gaussian.


title:
Time--consistent investment under model uncertainty: the robust forward
  criteria

abstract:
  We combine forward investment performance processes and ambiguity averse
portfolio selection. We introduce the notion of robust forward criteria which
addresses the issues of ambiguity in model specification and in preferences and
investment horizon specification. It describes the evolution of time-consistent
ambiguity averse preferences.
  We first focus on establishing dual characterizations of the robust forward
criteria. This offers various advantages as the dual problem amounts to a
search for an infimum whereas the primal problem features a saddle-point. Our
approach is based on ideas developed in Schied (2007) and Zitkovic (2009). We
then study in detail non-volatile criteria. In particular, we solve explicitly
the example of an investor who starts with a logarithmic utility and applies a
quadratic penalty function. The investor builds a dynamical estimate of the
market price of risk $\hat \lambda$ and updates her stochastic utility in
accordance with the so-perceived elapsed market opportunities. We show that
this leads to a time-consistent optimal investment policy given by a fractional
Kelly strategy associated with $\hat \lambda$. The leverage is proportional to
the investor's confidence in her estimate $\hat \lambda$.


title: SAT-Based Synthesis Methods for Safety Specs

abstract:
  Automatic synthesis of hardware components from declarative specifications is
an ambitious endeavor in computer aided design. Existing synthesis algorithms
are often implemented with Binary Decision Diagrams (BDDs), inheriting their
scalability limitations. Instead of BDDs, we propose several new methods to
synthesize finite-state systems from safety specifications using decision
procedures for the satisfiability of quantified and unquantified Boolean
formulas (SAT-, QBF- and EPR-solvers). The presented approaches are based on
computational learning, templates, or reduction to first-order logic. We also
present an efficient parallelization, and optimizations to utilize reachability
information and incremental solving. Finally, we compare all methods in an
extensive case study. Our new methods outperform BDDs and other existing work
on some classes of benchmarks, and our parallelization achieves a super-linear
speedup. This is an extended version of [5], featuring an additional appendix.


title: Two-loop Sunset Integrals at Finite Volume

abstract:
  We show how to compute the two-loop sunset integrals at finite volume, for
non-degenerate masses and non-zero momentum. We present results for all
integrals that appear in the Chiral Perturbation Therory ($\chi$PT) calculation
of the pseudoscalar meson masses and decay constants at NNLO, including the
case of Partially Quenched $\chi$PT. We also provide numerical implementations
of the finite-volume sunset integrals, and review the results for one-loop
integrals at finite volume.


title: Tangent bundle formulation of a charged gas

abstract:
  We discuss the relativistic kinetic theory for a simple, collisionless,
charged gas propagating on an arbitrary curved spacetime geometry. Our general
relativistic treatment is formulated on the tangent bundle of the spacetime
manifold and takes advantage of its rich geometric structure. In particular, we
point out the existence of a natural metric on the tangent bundle and
illustrate its role for the development of the relativistic kinetic theory.
This metric, combined with the electromagnetic field of the spacetime, yields
an appropriate symplectic form on the tangent bundle. The Liouville vector
field arises as the Hamiltonian vector field of a natural Hamiltonian. The
latter also defines natural energy surfaces, called mass shells, which turn out
to be smooth Lorentzian submanifolds.
  A simple, collisionless, charged gas is described by a distribution function
which is defined on the mass shell and satisfies the Liouville equation.
Suitable fibre integrals of the distribution function define observable fields
on the spacetime manifold, such as the current density and stress-energy
tensor. Finally, the geometric setting of this work allows us to discuss the
relationship between the symmetries of the electromagnetic field, those of the
spacetime metric, and the symmetries of the distribution function. Taking
advantage of these symmetries, we construct the most general solution of the
Liouville equation an a Kerr-Newman black hole background.


title: The Hot Bit I: The Szilard-Landauer Correspondence

abstract:
  We present a precise formulation of a correspondence between information and
thermodynamics that was first observed by Szilard, and later studied by
Landauer. The correspondence identifies available free energy with relative
entropy, and provides a dictionary between information and thermodynamics. We
precisely state and prove this correspondence. The paper should be broadly
accessible since we assume no prior knowledge of information theory, developing
it axiomatically, and we assume almost no thermodynamic background.


title: Enhancing the Energy Efficiency of Radio Base Stations

abstract:
  This thesis is concerned with the energy efficiency of cellular networks. It
studies the dominant power consumer in future cellular networks, the Long Term
Evolution radio base stations (BS), and proposes mechanisms that enhance the BS
energy efficiency by reducing its power consumption under target rate
constraints. These mechanisms trade spare capacity for power saving.


title:
Characterization of a medium size Xe/TMA TPC instrumented with microbulk
  Micromegas, using low-energy $\gamma$-rays

abstract:
  NEXT-MM is a general-purpose high pressure (10 bar, $\sim25$ l active volume)
Xenon-based TPC, read out in charge mode with an 8 cm $\times$8 cm-segmented
700 cm$^2$ plane (1152 ch) of the latest microbulk-Micromegas technology. It
has been recently commissioned at University of Zaragoza as part of the R&D of
the NEXT $0\nu\beta\beta$ experiment, although the experiment's first stage is
currently being built based on a SiPM/PMT-readout concept relying on
electroluminescence. Around 2 million events were collected during the last
months, stemming from the low energy $\gamma$-rays emitted by a $^{241}$Am
source when interacting with the Xenon gas ($\epsilon$ = 26, 30, 59.5 keV). The
localized nature of such events above atmospheric pressure, the long drift
times, as well as the possibility to determine their production time from the
associated $\alpha$ particle in coincidence, allow the extraction of primordial
properties of the TPC filling gas, namely the drift velocity, diffusion and
attachment coefficients. In this work we focus on the little explored
combination of Xe and trimethylamine (TMA) for which, in particular, such
properties are largely unknown. This gas mixture offers potential advantages
over pure Xenon when aimed at Rare Event Searches, mainly due to its Penning
characteristics, wave-length shifting properties and reduced diffusion, and it
is being actively investigated by our collaboration. The chamber is currently
operated at 2.7 bar, as an intermediate step towards the envisaged 10 bar. We
report here its performance as well as a first implementation of the
calibration procedures that have allowed the extension of the previously
reported energy resolution to the whole readout plane (10.6%FWHM@30keV).


title: Cavity mode entanglement in relativistic quantum information

abstract:
  A central aim of relativistic quantum information (RQI) is the investigation
of quantum information tasks and resources taking into account the relativistic
aspects of nature. More precisely, it is of fundamental interest to understand
how the storage, manipulation, and transmission of information utilizing
quantum systems are influenced by the fact that these processes take place in a
relativistic spacetime. In particular, many studies in RQI have been focused on
the effects of non-uniform motion on entanglement, the main resource of quantum
information protocols. Early investigations in this direction were performed in
highly idealized settings that prompted questions as to the practical
accessibility of these results. To overcome these limitations it is necessary
to consider quantum systems that are in principle accessible to localized
observers. In this thesis we present such a model, the rigid relativistic
cavity, and its extensions, focusing on the effects of motion on entanglement
and applications such as quantum teleportation. We study cavities in (1+1)
dimensions undergoing non-uniform motion, consisting of segments of uniform
acceleration and inertial motion of arbitrary duration that allow the involved
velocities to become relativistic. The transitions between segments can be
sharp or smooth and higher dimensions can be incorporated. The primary focus
lies in the Bogoliubov transformations of the quantum fields, real scalar
fields or Dirac fields, confined to the cavities. The Bogoliubov
transformations change the particle content and the occupation of the energy
levels of the cavity. We show how these effects generate entanglement between
the modes of the quantum fields inside a single cavity for various initial
states. The entanglement between several cavities, on the other hand, is
degraded by the non-uniform motion, influencing the fidelity of tasks such as
teleportation.


title:
Nonequilibrium dynamics of a mixed spin-1/2 and spin-3/2 Ising
  ferrimagnetic system with a time dependent oscillating magnetic field source

abstract:
  Nonequilibrium phase transition properties of a mixed Ising ferrimagnetic
model consisting of spin-1/2 and spin-3/2 on a square lattice under the
existence of a time dependent oscillating magnetic field have been investigated
by making use of Monte Carlo simulations with single-spin flip Metropolis
algorithm. A complete picture of dynamic phase boundary and magnetization
profiles have been illustrated and the conditions of a dynamic compensation
behavior have been discussed in detail. According to our simulation results,
the considered system does not point out a dynamic compensation behavior, when
it only includes the nearest-neighbor interaction, single-ion anisotropy and an
oscillating magnetic field source. As the next-nearest-neighbor interaction
between the spins-1/2 takes into account and exceeds a characteristic value
which sensitively depends upon values of single-ion anisotropy and only of
amplitude of external magnetic field, a dynamic compensation behavior occurs in
the system. Finally, it is reported that it has not been found any evidence of
dynamically first-order phase transition between dynamically ordered and
disordered phases, which conflicts with the recently published molecular field
investigation, for a wide range of selected system parameters.


title:
Noise analysis of single-qumode Gaussian operations using
  continuous-variable cluster states

abstract:
  We consider measurement-based quantum computation that uses scalable
continuous-variable cluster states with a one-dimensional topology. The
physical resource, known here as the dual-rail quantum wire, can be generated
using temporally multiplexed offline squeezing and linear optics or by using a
single optical parametric oscillator. We focus on an important class of quantum
gates, specifically Gaussian unitaries that act on single modes, which gives
universal quantum computation when supplemented with multi-mode operations and
photon-counting measurements. The dual-rail wire supports two routes for
applying single-qumode Gaussian unitaries: the first is to use traditional
one-dimensional quantum-wire cluster-state measurement protocols. The second
takes advantage of the dual-rail quantum wire in order to apply unitaries by
measuring pairs of qumodes called macronodes. We analyze and compare these
methods in terms of the suitability for implementing single-qumode Gaussian
measurement-based quantum computation.


title: What Mathematical Theories of Truth Should be Like (and Can be)

abstract:
  Hannes Leitgeb formulated eight norms for theories of truth in his paper:
`What Theories of Truth Should be Like (but Cannot be'). We shall present in
this paper a theory of truth for suitably constructed languages which contain
the first-order language of set theory, and prove that it satisfies all those
norms.


title: Supercurrent Spectroscopy of Andreev States

abstract:
  We measure the excitation spectrum of a superconducting atomic contact. In
addition to the usual continuum above the superconducting gap, the single
particle excitation spectrum contains discrete, spin-degenerate Andreev levels
inside the gap. Quasiparticle excitations are induced by a broadband on-chip
microwave source and detected by measuring changes in the supercurrent flowing
through the atomic contact. Since microwave photons excite quasiparticles in
pairs, two types of transitions are observed: Andreev transitions, which
consists of putting two quasiparticles in an Andreev level, and transitions to
odd states with a single quasiparticle in an Andreev level and the other one in
the continuum. In contrast to absorption spectroscopy, supercurrent
spectroscopy allows detection of long-lived odd states.


title: Evidence of an asteroid encountering a pulsar

abstract:
  Debris disks and asteroid belts are expected to form around young pulsars due
to fallback material from their original supernova explosions. Disk material
may migrate inwards and interact with a pulsar's magnetosphere, causing changes
in torque and emission. Long term monitoring of PSR J0738-4042 reveals both
effects. The pulse shape changes multiple times between 1988 and 2012. The
torque, inferred via the derivative of the rotational period, changes abruptly
from September 2005. This change is accompanied by an emergent radio component
that drifts with respect to the rest of the pulse. No known intrinsic pulsar
processes can explain these timing and radio emission signatures. The data lead
us to postulate that we are witnessing an encounter with an asteroid or
in-falling debris from a disk.


title:
One pion production in neutrino-nucleon scattering and the different
  parametrizations of the weak $N\rightarrow\Delta$ vertex

abstract:
  The $N \to \Delta$ weak vertex provides an important contribution to the one
pion production in neutrino-nucleon and neutrino-nucleus scattering for $\pi N$
invariant masses below 1.4 GeV. Beyond its interest as a tool in neutrino
detection and their background analyses, one pion production in
neutrino-nucleon scattering is useful to test predictions based on the quark
model and other internal symmetries of strong interactions. Here we try to
establish a connection between two commonly used parametrizations of the weak
$N \to \Delta$ vertex and form factors (FF) and we study their effects on the
determination of the axial coupling $C_5^A(0)$, the common normalization of the
axial FF, which is predicted to hold 1.2 by using the PCAC hypothesis.
Predictions for the $\nu_{\mu} p \to \mu^- p\pi^+$ total cross sections within
the two approaches, which include the resonant $\Delta^{++}$ and other
background contributions in a coherent way, are compared to experimental data.


title: Reductions on Double Occurrence Words

abstract:
  In the present paper we consider biologically motivated reduction operations
on double occurrence words. Then we define the nesting index of a double
occurrence word to be the least number of reduction operations it takes for a
word to be reduced to the empty word. We use chord diagrams and circle graphs
as tools to study the nesting index of double occurrence words.


title:
Response calculations based on an independent particle system with the
  exact one-particle density matrix: polarizabilities

abstract:
  Recently, we have demonstrated that the problems finding a suitable adiabatic
approximation in time-dependent one-body reduced density matrix functional
theory can be remedied by introducing an additional degree of freedom to
describe the system: the phase of the natural orbitals [Phys. Rev. Lett. 105,
013002 (2010), J. Chem. Phys. 133, 174119 (2010)]. In this article we will show
in detail how the frequency-dependent response equations give the proper static
limit ($\omega\to0$), including the perturbation in the chemical potential,
which is required in static response theory to ensure the correct number of
particles. Additionally we show results for the polarizability for H$_2$ and
compare the performance of two different two-electron functionals: the
phase-including L\"owdin-Shull functional and the density matrix form of the
L\"owdin-Shull functional.


title: Some examples of Hayward wormholes

abstract:
  The first part of this paper discusses a model for the theoretical
construction of a simple traversable wormhole with zero density that depends on
a preexisting black hole. By assuming the interconvertibilty of black holes and
wormholes proposed by S.A. Hayward, it is shown that a toy model suggested by
the first model may yield several possible transitions from the preexisting
black hole to a wormhole. A final topic is the conversion to a wormhole by
assuming a specific model for the exotic matter.


title: Differential-algebraic jet spaces preserve internality to the constants

abstract:
  This paper concerns the model theory of jet spaces (i.e., higher-order
tangent spaces) in differentially closed fields. Suppose p is the generic type
of the jet space to a finite dimensional differential-algebraic variety at a
generic point. It is shown that p satisfies a certain strengthening of almost
internality to the constant field called "preserving internality to the
constants". This strengthening is a model-theoretic abstraction of the generic
behaviour of jet spaces in complex-analytic geometry. A counterexample is
constructed showing that only this generic analogue holds in
differential-algebraic geometry.