title: Unquenched Meson Spectroscopy

abstract:
  Quantum chromodynamics (QCD), the quantum field theory of strong
interactions, is highly nonpertubative in the low-energy sector, where
confinement dominates and resonance phenomena are observed. Therefore,
phenomenological unquenched models based on the old ideas of the
$\mathcal{S}$-matrix theory give a fundamental contribution to understand the
complex pattern of masses, widths and shapes of experimentally observed meson
resonances. In the present thesis we employ the Resonance-Spectrum-Expansion
coupled-channel model to study two enigmatic meson states, the isoscalar vector
$\phi(2170)$ and the charmonium-like axial-vector $X(3872)$. The same model is
applied to describe the peculiar pattern of masses and widths of the open-charm
axial-vectors - pseudovectors $D_1(2420)$ and $D_1(2430)$, and $D_{s1}(2460)$
and $D_{s1}(2536)$. Furthermore, a simplified Schr\"{o}dinger model is used to
study the dominant wave-function components of $X(3872)$ near its resonance
mass. Both models successfully describe the whole variety of special features
observed in experiment, which are not so easily explained in QCD-inspired
quenched models.


title: The metric completion of the Riemannian space of K\"{a}hler metrics

abstract:
  Let $X$ be a compact K\"ahler manifold and $\a \in H^{1,1}(X,\R)$ a K\"ahler
class. We study the metric completion of the space $\HH_\a$ of K\"ahler metrics
in $\a$, when endowed with the Mabuchi $L^2$-metric $d$.
  Using recent ideas of Darvas, we show that the metric completion
$(\overline{\HH}_\a,d)$ of $(\HH_\a,d)$ is a CAT(0) space which can be
identified with $\E^2(\a)$, a subset of the class $\E^1(\a)$ of positive closed
currents with finite energy.
  We further prove, in the toric setting, that
$\overline{\HH}_{\a,tor}=\E_{tor}^2(\a)$.


title: Dense baryonic matter in the hidden local symmetry approach

abstract:
  The dense baryonic matter and hadron properties in medium were simulated by
using a Skyrme model including the ground state vector mesons introduced from
the hidden local symmetry approach up to the next to leading order. We found
that both the $\rho$ and $\omega$ mesons affect the baryonic matter and medium
modified hadron properties dramatically. The most remarkable observation is
that, the pion decay constant and the nucleon mass have the similar density
dependence which agrees with the large $N_c$ argument. Explicitly, they drop
with increasing density in the Skyrmion phase and stop decreasing at
$n_{1/2}^{}$ at which the skyrmions in medium fractionize into half-skyrmions
and remains nearly constants in the half-skyrmion phase. This density
dependence in the half-skyrmion phase indicates that, although $\langle
\bar{q}q\rangle \neq 0$ on average in this phase, chiral symmetry is not
restored since hadrons are still massive and there exist pions. In addition,
the nearly constant nucleon mass means that it could has a non-vanishing
component up to the chiral transition, which might shed light on the origin of
the nucleon mass.


title:
Nonlinear Propagation of Coherent States through Avoided Energy Level
  Crossing

abstract:
  We study the propagation of wave packets for a one-dimensional system of two
coupled Schr\"odinger equations with a cubic nonlinearity, in the
semi-classical limit. Couplings are induced by the nonlinearity and by the
potential, whose eigenvalues present an "avoided crossing": at one given point,
the gap between them reduces as the semi-classical parameter becomes smaller.
For data which are coherent states polarized along an eigenvector of the
potential, we prove that when the wave function propagates through the avoided
crossing point, there are transitions between the eigenspaces at leading order.
We analyze the nonlinear effects, which are noticeable away from the crossing
point, but see that in a small time interval around this point, the
nonlinearity's role is negligible at leading order, and the transition
probabilities can be computed with the linear Landau-Zener formula.


title: Motion planning and control of a planar polygonal linkage

abstract:
  For a polygonal linkage, we produce a fast navigation algorithm on its
configuration space. The basic idea is to approximate the configuration space
by the vertex-edge graph of its cell decomposition discovered by the first
author. The algorithm has three aspects: (1) the number of navigation steps
does not exceed 15 (independent of the linkage), (2) each step is a disguised
flex of a quadrilateral from one triangular configuration to another, which is
a well understood type of flex, and (3) each step can be performed explicitly
by adding some extra bars and obtaining a mechanism with one degree of freedom.


title:
The Subgroup Normalizer Problem for Integral Group Rings of some
  Nilpotent and Metacyclic Groups

abstract:
  For a group $G$ and a subgroup $H$ of $G$ this article discusses the
normalizer of $H$ in the units of a group ring $RG$. We prove that $H$ is only
normalized by the `obvious' units, namely products of elements of $G$
normalizing $H$ and units of $RG$ centralizing $H$, provided $H$ is cyclic.
Moreover we show that the normalizers of all subgroups of certain nilpotent and
metacyclic groups in the corresponding group rings are as small as possible.
These classes contain all dihedral groups, all finite nilpotent groups and all
finite groups with all Sylow subgroups being cyclic.


title:
Optical Polarimetry and modeling of polars observed in OPD/LNA in the
  period 2010-2012

abstract:
  In this work, we present the first results of a study of a new sample of 7
polar candidates from polarimetric data obtained at the Pico dos Dias / LNA
observatory. From the four polars analysed so far, we confirm the presence of
high and variable polarization in 3. The data will be analysed using the code
CYCLOPS.


title: A Denjoy counterexample for circle maps with an half-critical point

abstract:
  Modifying Hall's idea in "A C^{\infty} Denjoy counterexample" we construct an
example of homeomorphism of the circle which is a Denjoy counterexample (i.e.
it is not conjugated to a rotation) and which is a C^{\infty}-diffeomorphism
everywhere except in a flat half-critical point.


title: Dispersive Shock Waves in Viscously Deformable Media

abstract:
  The viscously dominated, low Reynolds' number dynamics of multi-phase,
compacting media can lead to nonlinear, dissipationless/dispersive behavior
when viewed appropriately. In these systems, nonlinear self-steepening competes
with wave dispersion, giving rise to dispersive shock waves (DSWs). Example
systems considered here include magma migration through the mantle as well as
the buoyant ascent of a low density fluid through a viscously deformable
conduit. These flows are modeled by a third-order, degenerate, dispersive,
nonlinear wave equation for the porosity (magma volume fraction) or
cross-sectional area, respectively. Whitham averaging theory for step initial
conditions is used to compute analytical, closed form predictions for the DSW
speeds and the leading edge amplitude in terms of the constitutive parameters
and initial jump height. Novel physical behaviors are identified including
backflow and DSW implosion for initial jumps sufficient to cause gradient
catastrophe in the Whitham modulation equations. Theoretical predictions are
shown to be in excellent agreement with long-time numerical simulations for the
case of small to moderate amplitude DSWs. Verifiable criteria identifying the
breakdown of this modulation theory in the large jump regime, applicable to a
wide class of DSW problems, are presented.


title: Comment on "Nanoscale Heat Engine Beyond the Carnot Limit"

abstract:
  There exists a consistent thermodynamical formalism with canonical definition
of local temperatures which allows to extend the Carnot bound also to
non-equilibrium baths, like those discussed in the Letter


title: Evolution of the cosmic web

abstract:
  The cosmic web is the largest scale manifestation of the anisotropic
gravitational collapse of matter. It represents the transitional stage between
linear and non-linear structures and contains easily accessible information
about the early phases of structure formation processes. Here we investigate
the characteristics and the time evolution of morphological components since.
Our analysis involves the application of the NEXUS Multiscale Morphology Filter
(MMF) technique, predominantly its NEXUS+ version, to high resolution and large
volume cosmological simulations. We quantify the cosmic web components in terms
of their mass and volume content, their density distribution and halo
populations. We employ new analysis techniques to determine the spatial extent
of filaments and sheets, like their total length and local width. This analysis
identifies cluster and filaments as the most prominent components of the web.
In contrast, while voids and sheets take most of the volume, they correspond to
underdense environments and are devoid of group-sized and more massive haloes.
At early times the cosmos is dominated by tenuous filaments and sheets, which,
during subsequent evolution, merge together, such that the present day web is
dominated by fewer, but much more massive, structures. The analysis of the mass
transport between environments clearly shows how matter flows from voids into
walls, and then via filaments into cluster regions, which form the nodes of the
cosmic web. We also study the properties of individual filamentary branches, to
find long, almost straight, filaments extending to distances larger than
100Mpc/h. These constitute the bridges between massive clusters, which seem to
form along approximatively straight lines.


title:
Remarks on the Tripos To Topos Construction: extensionality,
  comprehensions, quotients and cauchy-complete objects

abstract:
  We give a description of the Tripos To Topos construction in terms of four
free constructions. We prove that these compose up to give a free construction
from the category of triposes and logical morphisms to the category of toposes
and logical functors. Then we show that other similar constructions, i.e. the
one given by Frey in \cite{frey} and that of Carboni in \cite{carbons} are
instances of this one.


title: Analysis of selected Kepler Mission planetary light curves

abstract:
  We have modified the graphical user interfaced close binary system analysis
program CurveFit to the form WinKepler and applied it to 16 representative
planetary candidate light curves found in the NASA Exoplanet Archive (NEA) at
the Caltech website http://exoplanetarchive.ipac.caltech.edu, with an aim to
compare different analytical approaches. WinKepler has parameter options for a
realistic physical model, including gravity-brightening and structural
parameters derived from the relevant Radau equation. We tested our best-fitting
parameter-sets for formal determinacy and adequacy.
  A primary aim is to compare our parameters with those listed in the NEA.
Although there are trends of agreement, small differences in the main parameter
values are found in some cases, and there may be some relative bias towards a
90 degrees value for the NEA inclinations. These are assessed against realistic
error estimates.
  Photometric variability from causes other than planetary transits affects at
least 6 of the data-sets studied; with small pulsational behaviour found in 3
of those. For the false positive KOI 4.01, we found that the eclipses could be
modelled by a faint background classical Algol as effectively as by a
transiting exoplanet. Our empirical checks of limb-darkening, in the cases of
KOI 1.01 and 12.01, revealed that the assigned stellar temperatures are
probably incorrect. For KOI 13.01, our empirical mass-ratio differs by about 7%
from that of Mislis and Hodgkin (2012), who neglected structural effects and
higher order terms in the tidal distortion. Such detailed parameter evaluation,
additional to the usual main geometric ones, provides an additional objective
for this work.


title: Polynomial actions of unitary operators and idempotent ultrafilters

abstract:
  Let $p$ be an idempotent ultrafilter over $\mathbb{N}$. For a positive
integer $N$, let ${\cal P}_{\leq N}$ denote the additive group of polynomials
$P\in\mathbb{Z}[x]$ with ${\rm deg}\, P\leq N$ and $P(0)=0$. Given a unitary
operator $U$ on a Hilbert space ${\cal H}$, we prove, for each $N\geq1$, the
existence of a unique decomposition ${\cal H}=\bigoplus_{r\geq 1}{\cal
H}^{(N)}_r$ into closed, $U$-invariant subspaces such that
  (a) for any polynomial $P\in{\cal P}_{\leq N}$, we have $$ p\,
\text{-}\!\lim_{n\in\mathbb{N}} \left(U|_{{\cal
H}_r^{(N)}}\right)^{P(n)}=0_{{\cal H}_r^{(N)}}\;\mbox{or}\; Id_{{\cal
H}_r^{(N)}},\; \mbox{for each}\; r\geq1 ; $$ (b) for each $r\neq s$ there
exists $Q\in{\cal P}_{\leq N}$ such that $$ p\,\text{-}\!\lim_{n\in\mathbb{N}}
\left(U|_{{\cal H}_r^{(N)}}\right)^{Q(n)}\neq
p\,\text{-}\!\lim_{n\in\mathbb{N}} \left(U|_{{\cal H}_s^{(N)}}\right)^{Q(n)}.
$$
  In connection with this result we introduce the notion of rigidity group.
Namely, a subgroup $G\subset {\cal P}_{\leq N}$ is called an $N$-rigidity group
if there exist an idempotent ultrafilter $p$ over $\mathbb{N}$ and a unitary
operator $U$ on a Hilbert space $\cal H$ such that $$\label{ab1} G=\{P\in{\cal
P}_{\leq N}:\: p\,\text{-}\!\lim_{n\in\mathbb{N}} U ^{P(n)}=Id\}$$ and
$p\,\text{-}\!\lim_{n\in\mathbb{N}} U ^{Q(n)}=0\;\;\mbox{for each}\;\;Q\in{\cal
P}_{\leq N}\setminus G.$
  The main result of the paper states that a subgroup $G\subset {\cal P}_{\leq
N}$ satisfying $\max\{{\rm deg}\, P:\:P\in G\}=N$ is an $N$-rigidity group if
and only if $G$ has finite index in ${\cal P}_{\leq N}$.


title:
Determination of the origin and magnitude of logarithmic finite-size
  effects on interfacial tension: Role of interfacial fluctuations and domain
  breathing

abstract:
  The ensemble-switch method for computing wall excess free energies of
condensed matter is extended to estimate the interface free energies between
coexisting phases very accurately. By this method, system geometries with
linear dimensions $L$ parallel and $L_z$ perpendicular to the interface with
various boundary conditions in the canonical or grandcanonical ensemble can be
studied. Using two- and three-dimensional Ising models, the nature of the
occurring logarithmic finite size corrections is studied. It is found crucial
to include interfacial fluctuations due to "domain breathing".


title:
Properties of Starless and Prestellar Cores in Taurus Revealed by
  Herschel SPIRE/PACS Imaging

abstract:
  The density and temperature structures of dense cores in the L1495 cloud of
the Taurus star-forming region are investigated using Herschel SPIRE and PACS
images in the 70 $\mu$m, 160 $\mu$m, 250 $\mu$m, 350 $\mu$m and 500 $\mu$m
continuum bands. A sample consisting of 20 cores, selected using spectral and
spatial criteria, is analysed using a new maximum likelihood technique,
COREFIT, which takes full account of the instrumental point spread functions.
We obtain central dust temperatures, $T_0$, in the range 6-12 K and find that,
in the majority of cases, the radial density falloff at large radial distances
is consistent with the $r^{-2}$ variation expected for Bonnor-Ebert spheres.
Two of our cores exhibit a significantly steeper falloff, however, and since
both appear to be gravitationally unstable, such behaviour may have
implications for collapse models. We find a strong negative correlation between
$T_0$ and peak column density, as expected if the dust is heated predominantly
by the interstellar radiation field. At the temperatures we estimate for the
core centres, carbon-bearing molecules freeze out as ice mantles on dust
grains, and this behaviour is supported here by the lack of correspondence
between our estimated core locations and the previously-published positions of
H$^{13}$CO$^+$ peaks. On this basis, our observations suggest a
sublimation-zone radius typically $\sim 10^4$ AU. Comparison with
previously-published N$_2$H$^+$ data at 8400 AU resolution, however, shows no
evidence for N$_2$H$^+$ depletion at that resolution.


title:
On the conflict between precision and robustness in the proportion
  regulation of cell types

abstract:
  In Dictyostelium discoideum the proportion of cell types is known to be
actively regulated, recovering, for example, after the removal of a given cell
type. However, we have recently shown that regulation is intrinsically
imprecise: it controls the proportion above/below certain upper and lower
thresholds, but not within an allowed range of values that these thresholds
define. To explain this finding we present a model based on (i) a global
negative feedback, and (ii) a cell-autonomous positive feedback leading to a
hysteresis-like behaviour (i.e, a bistability of cell type). The simulated
cell-type proportion is indeed found to span a range of values as a consequence
of the bistability. We conclude that there is a general conflict between the
precision of proportion regulation and the robustness of the differentiation of
cell types.


title:
A high-statistics measurement of transverse spin effects in dihadron
  production from muon-proton semi-inclusive deep-inelastic scattering

abstract:
  A measurement of the azimuthal asymmetry in dihadron production in
deep-inelastic scattering of muons on transversely polarised proton (NH$_{3}$)
targets are presented. They provide independent access to the transversity
distribution functions through the measurement of the Collins asymmetry in
single hadron production. The data were taken in the year $2010$ with the
COMPASS spectrometer using a $160\,\mbox{GeV}/c$ muon beam of the CERN SPS,
increasing by a factor of about three the available statistics of the
previously published data taken in the year $2007$. The measured sizeable
asymmetry is in good agreement with the published data. An approximate equality
of the Collins asymmetry and the dihadron asymmetry is observed, suggesting a
common physical mechanism in the underlying fragmentation.


title:
Multi-Pulse Laser Wakefield Acceleration: A New Route to Efficient,
  High-Repetition-Rate Plasma Accelerators and High Flux Radiation Sources

abstract:
  Laser-driven plasma accelerators can generate accelerating gradients three
orders of magnitude larger than radio-frequency accelerators and have achieved
beam energies above 1 GeV in centimetre long stages. However, the pulse
repetition rate and wall-plug efficiency of plasma accelerators is limited by
the driving laser to less than approximately 1 Hz and 0.1% respectively. Here
we investigate the prospects for exciting the plasma wave with trains of
low-energy laser pulses rather than a single high-energy pulse. Resonantly
exciting the wakefield in this way would enable the use of different
technologies, such as fibre or thin-disc lasers, which are able to operate at
multi-kilohertz pulse repetition rates and with wall-plug efficiencies two
orders of magnitude higher than current laser systems. We outline the
parameters of efficient, GeV-scale, 10-kHz plasma accelerators and show that
they could drive compact X-ray sources with average photon fluxes comparable to
those of third-generation light source but with significantly improved temporal
resolution. Likewise FEL operation could be driven with comparable peak power
but with significantly larger repetition rates than extant FELs.


title: Photon Generation from Quantum Vacuum using a Josephson Metamaterial

abstract:
  When one of the parameters in the Euler-Lagrange equations of motion of a
system is modulated, particles can be generated out of the quantum vacuum. This
phenomenon is known as the dynamical Casimir effect, and it was recently
realized experimentally in systems of superconducting circuits, for example by
using modulated resonators made of coplanar waveguides, or arrays of
superconducting quantum intereference devices (SQUIDs) forming a Josephson
metamaterial. In this paper, we consider a simple electrical circuit model for
dynamical Casimir effects, consisting of an LC resonator, with the inductor
modulated externally at 10.8 GHz and with the resonant frequency tunable over a
range of $\pm$ 400 MHz around 5.4 GHz. The circuit is analyzed classically
using a circuit simulator (APLAC). We demonstrate that if an additional source
of classical noise couples to the resonator (on top of the quantum vacuum), for
example via dissipative "internal modes", then the resulting spectrum of the
photons in the cavity will present two strongly asymmetric branches. However,
according to the theory of the dynamical Casimir effect, these branches should
be symmetric, a prediction which is confirmed by our experimental data. The
simulation presented here therefore shows that the origin of the photons
generated in our experiment with Josephson metamaterials is the quantum vacuum,
and not a spurious classical noise source.


title:
Remarkable effects of disorder on superconductivity of single atomic
  layers of lead on silicon

abstract:
  In bulk materials superconductivity is remarkably robust with respect to
non-magnetic disorder. In the two-dimensional limit however, the quantum
condensate suffers from the effects produced by disorder and electron
correlations which both tend to destroy superconductivity . The recent
discovery of superconductivity in single atomic layers of Pb, the striped
incommensurate (SIC) and $\sqrt{7}\times\sqrt{3}$ Pb/Si(111), opened an unique
opportunity to probe the influence of well-identified structural disorder on
two-dimensional superconductivity at the atomic and mesoscopic scale. In these
two ultimate condensates we reveal how the superconducting spectra loose their
conventional character, by mapping the local tunneling density of states. We
report variations of the spectral properties even at scales significantly
shorter than the coherence length. Furthermore, fine structural differences
between the two monolayers, such as their atomic density, lead to very
different superconducting behaviour. The denser SIC remains globally robust to
disorder, as are thicker Pb films, whereas in the slighly more diluted
$\sqrt{7}\times\sqrt{3}$ system superconductivity is strongly fragilized. A
consequence of this weakness is revealed at monoatomic steps of
$\sqrt{7}\times\sqrt{3}$, which disrupt superconductivity at the atomic scale.
This effect witnesses that each individual step edge is a Josephson barrier. At
a mesoscopic scale the weakly linked superconducting atomic terraces of
$\sqrt{7}\times\sqrt{3}$ form a native network of Josephson junctions. We
anticipate the Pb/Si(111) system to offer the unique opportunity to tune the
superconducting coupling between adjacent terraces, paving a new way of
designing atomic scale quantum devices compatible with silicon technology.


title: Void magnetic field and its primordial origin in inflation

abstract:
  Since magnetic fields in galaxies, galactic clusters and even void regions
are observed, theoretical attempts to explain their origin are strongly
motivated. It is interesting to consider that inflation is responsible for the
origin of the magnetic fields as well as the density perturbation. However, it
is known that inflationary magnetogenesis suffers from several problems. We
explore these problems by using a specific model, namely the kinetic coupling
model, and show how the model is constrained. Model independent arguments are
also discussed.


title:
A new method for classifying galaxy SEDs from multi-wavelength
  photometry

abstract:
  We present a new method to classify the broad band optical-NIR spectral
energy distributions (SEDs) of galaxies using three shape parameters
(super-colours) based on a Principal Component Analysis of model SEDs. As well
as providing a compact representation of the wide variety of SED shapes, the
method allows for easy visualisation of information loss and biases caused by
the incomplete sampling of the rest-frame SED as a function of redshift. We
apply the method to galaxies in the UKIDSS Ultra Deep Survey with 0.9<z<1.2,
and confirm our classifications by stacking rest-frame optical spectra for a
fraction of objects in each class. As well as cleanly separating a tight
red-sequence from star-forming galaxies, three unusual populations are
identifiable by their unique colours: very dusty star-forming galaxies with
high metallicity and old mean stellar age; post-starburst galaxies which have
formed greater than around 10% of their mass in a recent unsustained starburst
event; and metal-poor quiescent dwarf galaxies. We find that quiescent galaxies
account for 45% of galaxies with log(M*/Msol)>11, declining steadily to 13% at
log(M*/Msol)=10. The properties and mass-function of the post-starburst
galaxies are consistent with a scenario in which gas-rich mergers contribute to
the growth of the low and intermediate mass range of the red sequence.


title:
Observational studies on the Near-Infrared Unidentified Emission Bands
  in Galactic HII regions

abstract:
  Using a large collection of near-infrared spectra (2.5-5.4 um) of Galactic
HII regions and HII region-like objects, we perform a systematic investigation
of the astronomical polycyclic aromatic hydrocarbon (PAH) features. 36 objects
were observed by the use of the infrared camera onboard the AKARI satellite as
a part of a directer's time program. In addition to the well-known 3.3-3.6 um
features, most spectra show a relatively-weak emission feature at 5.22 um with
sufficient signal-to-noise ratios, which we identify as the PAH 5.25 um band
previously reported. By careful analysis, we find good correlations between the
5.25 um band and both the aromatic hydrocarbon feature at 3.3 um and the
aliphatic ones at around 3.4-3.6 um. The present results give us convincing
evidence that the astronomical 5.25 um band is associated with C-H vibrations
as suggested by previous studies and show its potential to probe the PAH size
distribution. The analysis also shows that the aliphatic to aromatic ratio of
I(3.4-3.6)/I(3.3) decreases against the ratio of the 3.7 um continuum intensity
to the 3.3 um band, I(3.7 cont)/I(3.3), which is an indicator of the ionization
fraction of PAHs. The mid-infrared color of I(9)/I(18) also declines steeply
against the ratio of the hydrogen recombination line Bralpha at 4.05 um to the
3.3 um band, I(Bralpha)/I(3.3). These facts indicate possible dust processing
inside or at the boundary of ionized gas.


title:
Scaling of Magneto-Quantum-Radiative Hydrodynamic Equations: From
  Laser-produced Plasmas to Astrophysics

abstract:
  We introduce here the equations of magneto-quantum-radiative hydrodynamics.
By rewriting them in a dimensionless form, we obtain a set of parameters that
describe scale-dependent ratios of all the characteristic hydrodynamic
quantities. We discuss how these dimensionless parameters relate to the scaling
between astrophysical observations and laboratory experiments.


title:
Accurate numerical simulation of radiation reaction effects in strong
  electromagnetic fields

abstract:
  The Landau-Lifshitz equation provides an efficient way to account for the
effects of radiation reaction without acquiring the non-physical solutions
typical for the Lorentz-Abraham-Dirac equation. We solve the Landau-Lifshitz
equation in its covariant four-vector form in order to control both the energy
and momentum of radiating particle. Our study reveals that implicit
time-symmetric collocation methods of the Runge-Kutta-Nystr\"om type are
superior in both accuracy and better maintaining the mass-shell condition than
their explicit counterparts. We carry out an extensive study of numerical
accuracy by comparing the analytical and numerical solutions of the
Landau-Lifshitz equation. Finally, we present the results of simulation of
particles scattering by a focused laser pulse. Due to radiation reaction,
particles are less capable for penetration into the focal region, as compared
to the case of radiation reaction neglected. Our results are important for
designing the forthcoming experiments with high intensity laser fields.


title:
An O(log N) Parallel Algorithm for Newton Step Computation in Model
  Predictive Control

abstract:
  The use of Model Predictive Control in industry is steadily increasing as
more complicated problems can be addressed. Due to that online optimization is
usually performed, the main bottleneck with Model Predictive Control is the
relatively high computational complexity. Hence, a lot of research has been
performed to find efficient algorithms that solve the optimization problem. As
parallelism is becoming more commonly used in hardware, the demand for
efficient parallel solvers for Model Predictive Control has increased. In this
paper, a tailored parallel algorithm that can adopt different levels of
parallelism for solving the Newton step is presented. With sufficiently many
processing units, it is capable of reducing the computational growth to
logarithmic growth in the prediction horizon. Since the Newton step computation
is where most computational effort is spent in both interior-point and
active-set solvers, this new algorithm can significantly reduce the
computational complexity of highly relevant solvers for Model Predictive
Control.


title: Scaling a unitary matrix

abstract:
  The iterative method of Sinkhorn allows, starting from an arbitrary real
matrix with non-negative entries, to find a so-called 'scaled matrix' which is
doubly stochastic, i.e. a matrix with all entries in the interval (0, 1) and
with all line sums equal to 1. We conjecture that a similar procedure exists,
which allows, starting from an arbitrary unitary matrix, to find a scaled
matrix which is unitary and has all line sums equal to 1. The existence of such
algorithm guarantees a powerful decomposition of an arbitrary quantum circuit.


title: Relativistic ring models

abstract:
  Relativistic thick ring models are constructed using previously found
analytical Newtonian potential-density pairs for flat rings and toroidal
structures obtained from Kuzmin-Toomre family of discs. In particular, we
present systems with one ring, two rings and a disc with a ring. Also, the
circular velocity of a test particle and its stability when performing circular
orbits are presented in all these models. In general, we find that regions of
non-stability appear between the rings when they become thinner.


title:
Langevin spin dynamics based on ab initio calculations: numerical
  schemes and applications

abstract:
  A method is proposed to study the finite-temperature behaviour of small
magnetic clusters based on solving the stochastic Landau-Lifshitz-Gilbert
equations, where the effective magnetic field is calculated directly during the
solution of the dynamical equations from first principles instead of relying on
an effective spin Hamiltonian. Different numerical solvers are discussed in the
case of a one-dimensional Heisenberg chain with nearest-neighbour interactions.
We performed detailed investigations for a monatomic chain of ten Co atoms on
top of Au(001) surface. We found a spiral-like ground state of the spins due to
Dzyaloshinsky-Moriya interactions, while the finite-temperature magnetic
behaviour of the system was well described by a nearest-neighbour Heisenberg
model including easy-axis anisotropy.


title: Balancing lists: a proof pearl

abstract:
  Starting with an algorithm to turn lists into full trees which uses
non-obvious invariants and partial functions, we progressively encode the
invariants in the types of the data, removing most of the burden of a
correctness proof.
  The invariants are encoded using non-uniform inductive types which parallel
numerical representations in a style advertised by Okasaki, and a small amount
of dependent types.


title: Single Molecule FRET Reveals Pore Size and Opening Mechanism of MscL

abstract:
  The mechanosensitive channel of large conductance, which serves as a model
system for mechanosensitive channels, has previously been crystallized in the
closed form, but not in the open form. Ensemble measurements and
electrophysiological sieving experiments show that the open-diameter of the
channel pore is >25{\AA}, but the exact size and whether the conformational
change follows a helix-tilt or barrel-stave model are unclear. Here we report
measurements of the distance changes on liposome-reconstituted MscL
transmembrane {\alpha}-helices, using a "virtual sorting" single-molecule
fluorescence energy transfer. We observed directly that the channel opens via
the helix-tilt model and the open pore reaches 2.8 nm in diameter. In addition,
based on the measurements, we developed a molecular dynamics model of the
channel structure in the open state which confirms our direct observations.


title:
Baryon stopping in the Color Glass Condensate formalism: A
  phenomenological study

abstract:
  The net-baryon production at forward rapidities is investigated considering
the Color Glass Condensate formalism. We assume that at large energies the
coherence of the projectile quarks is lost and that the leading baryon
production mechanism changes from recombination to independent fragmentation.
The phenomenological implications for net-baryon production in $pp/pA/AA$
collisions are analysed and predictions for LHC energies are presented.


title:
Direct constructions for general families of cyclic mutually nearly
  orthogonal Latin squares

abstract:
  Two Latin squares $L=[l(i,j)]$ and $M=[m(i,j)]$, of even order $n$ with
entries $\{0,1,2,\ldots,n-1\}$, are said to be nearly orthogonal if the
superimposition of $L$ on $M$ yields an $n\times n$ array $A=[(l(i,j),m(i,j))]$
in which each ordered pair $(x,y)$, $0\leq x,y\leq n-1$ and $x\neq y$, occurs
at least once and the ordered pair $(x,x+n/2)$ occurs exactly twice. In this
paper, we present direct constructions for the existence of general families of
three cyclic mutually orthogonal Latin squares of orders $48k+14$, $48k+22$,
$48k+38$ and $48k+46$. The techniques employed are based on the principle of
Methods of Differences and so we also establish infinite classes of
"quasi-difference" sets for these orders.


title:
Exploring the Relationship between Membership Turnover and Productivity
  in Online Communities

abstract:
  One of the more disruptive reforms associated with the modern Internet is the
emergence of online communities working together on knowledge artefacts such as
Wikipedia and OpenStreetMap. Recently it has become clear that these
initiatives are vulnerable because of problems with membership turnover. This
study presents a longitudinal analysis of 891 WikiProjects where we model the
impact of member turnover and social capital losses on project productivity. By
examining social capital losses we attempt to provide a more nuanced analysis
of member turnover. In this context social capital is modelled from a social
network perspective where the loss of more central members has more impact. We
find that only a small proportion of WikiProjects are in a relatively healthy
state with low levels of membership turnover and social capital losses. The
results show that the relationship between social capital losses and project
performance is U-shaped, and that member withdrawal has significant negative
effect on project outcomes. The results also support the mediation of turnover
rate and network density on the curvilinear relationship.


title: Multiple Scales in Pati-Salam Unification Models

abstract:
  We investigate models where gauge unification (GUT) proceeds in steps that
include Pati-Salam symmetry. Beyond the Standard Model, we allow for a
well-defined set of small representations of the GUT gauge group. We show that
all possible chains of Pati-Salam symmetry breaking can be realized in
accordance with gauge-coupling unification. We identify, in particular, models
with unification near the Planck scale, with intermediate left-right or SU(4)
quark-lepton symmetries that are relevant for flavor physics, with new colored
particles at accessible energies, and with an enlarged electroweak Higgs
sector. We look both at supersymmetric and non-supersymmetric scenarios.


title:
Nonlinear switching in a concentric ring core chalcogenide glass optical
  fiber for passively mode-locking a fiber laser

abstract:
  We propose an all-fiber mode-locking device which operates based on nonlinear
switching in a novel concentric ring core fiber structure. The design is
particularly attractive given the ease of fabrication and coupling to other
components in a mode-locked fiber laser cavity. The nonlinear switching in this
coupler is studied and the relative power transmission is obtained. The
analysis shows that this nonlinear switch is practical for mode-locking fiber
lasers and is forgiving to fabrication errors.


title: Inference with penalized likelihood

abstract:
  This work studies the statistical properties of the maximum penalized
likelihood approach in a semi-parametric framework. We recall the penalized
likelihood approach for estimating a function and review some asymptotic
results. We investigate the properties of two estimators of the variance of
maximum penalized likelihood estimators: sandwich estimator and a Bayesian
estimator. The coverage rates of confidence intervals based on these estimators
are studied through a simulation study of survival data. In a first simulation
the coverage rates for the survival function and the hazard function are
evaluated. In a second simulation data are generated from a proportional hazard
model with covariates. The estimators of the variances of the regression
coefficients are studied. As for the survival and hazard functions, both
sandwich and Bayesian estimators exhibit relatively good properties, but the
Bayesian estimator seems to be more accurate. As for the regression
coefficients, we focussed on the Bayesian estimator and found that it yielded
good coverage rates.


title: The Peierls argument for higher dimensional Ising models

abstract:
  The Peierls argument is a mathematically rigorous and intuitive method to
show the presence of a non-vanishing spontaneous magnetization in some lattice
models. This argument is typically explained for the $D=2$ Ising model in a way
which cannot be easily generalized to higher dimension. The aim of this paper
is to present an elementary discussion of the Peierls argument for the general
$D$-dimensional Ising model.


title: The Theorem of Halmos and Savage under Finite Additivity

abstract:
  Given a generalization of Lebesgue decomposition we obtain an extension to
the finitely additive setting of the theorems of Halmos and Savage and of Yan.


title: Coincidence of extendible vector-valued ideals with their minimal kernel

abstract:
  We provide coincidence results for vector-valued ideals of multilinear
operators. More precisely, if $\mathfrak A$ is an ideal of $n$-linear mappings
we give conditions for which the following equality $\mathfrak
A(E_1,\dots,E_n;F) = {\mathfrak A}^{min}(E_1,\dots,E_n;F)$ holds isometrically.
As an application, we obtain in many cases that the monomials form a Schauder
basis on the space $\mathfrak A(E_1,\dots,E_n;F)$. Several structural and
geometric properties are also derived using this equality. We apply our results
to the particular case where $\mathfrak A$ is the classical ideal of extendible
or Pietsch-integral multilinear operators. Similar statements are given for
ideals of vector-valued homogeneous polynomials.


title:
Electronic structure of BaNi$_2$P$_2$ observed by angle-resolved
  photoemission spectroscopy

abstract:
  We have performed an angle-resolved photoemission spectroscopy (ARPES) study
of BaNi$_2$P$_2$ which shows a superconducting transition at $T_c$ $\sim$ 2.5
K. We observed hole and electron Fermi surfaces (FSs) around the Brillouin zone
center and corner, respectively, and the shapes of the hole FSs dramatically
changed with photon energy, indicating strong three-dimensionality. The
observed FSs are consistent with band-structure calculation and de Haas-van
Alphen measurements. The mass enhancement factors estimated in the normal state
were $m^*$/$m_b$ $\leq$ 2, indicating weak electron correlation compared to
typical iron-pnictide superconductors. An electron-like Fermi surface around
the Z point was observed in contrast with BaNi$_2$As$_2$ and may be related to
the higher $T_c$ of BaNi$_2$P$_2$.


title: Maximum Margin Multiclass Nearest Neighbors

abstract:
  We develop a general framework for margin-based multicategory classification
in metric spaces. The basic work-horse is a margin-regularized version of the
nearest-neighbor classifier. We prove generalization bounds that match the
state of the art in sample size $n$ and significantly improve the dependence on
the number of classes $k$. Our point of departure is a nearly Bayes-optimal
finite-sample risk bound independent of $k$. Although $k$-free, this bound is
unregularized and non-adaptive, which motivates our main result: Rademacher and
scale-sensitive margin bounds with a logarithmic dependence on $k$. As the best
previous risk estimates in this setting were of order $\sqrt k$, our bound is
exponentially sharper. From the algorithmic standpoint, in doubling metric
spaces our classifier may be trained on $n$ examples in $O(n^2\log n)$ time and
evaluated on new points in $O(\log n)$ time.


title: Quantifying identifiability in independent component analysis

abstract:
  We are interested in consistent estimation of the mixing matrix in the ICA
model, when the error distribution is close to (but different from) Gaussian.
In particular, we consider $n$ independent samples from the ICA model $X =
A\epsilon$, where we assume that the coordinates of $\epsilon$ are independent
and identically distributed according to a contaminated Gaussian distribution,
and the amount of contamination is allowed to depend on $n$. We then
investigate how the ability to consistently estimate the mixing matrix depends
on the amount of contamination. Our results suggest that in an asymptotic
sense, if the amount of contamination decreases at rate $1/\sqrt{n}$ or faster,
then the mixing matrix is only identifiable up to transpose products. These
results also have implications for causal inference from linear structural
equation models with near-Gaussian additive noise.


title:
New libraries for simulating neutron scattering in dark matter detector
  calibrations

abstract:
  Dark matter detectors require calibrations of their energy scale and
efficiency to detect nuclear recoils in the $1-50$ keV range. Most calibrations
use neutron scattering and require MCNP or Geant4 simulations of neutron
propagation through the detector. For most nuclei heavier than $^{16}$O, these
simulations' libraries ignore the contribution of resolved resonances to the
neutron elastic differential cross-section. For many isotopes and neutron
energies of importance to dark matter detection, this invalid assumption can
severely distort simulated nuclear recoil spectra. The correct angular
distributions can be calculated from the resonance parameters using R-matrix
formalism. A set of neutron scattering libraries with high resolution angular
distributions for MCNP and Geant4 of $^{19}$F, $^{40}$Ar, $^{50,52}$Cr,
$^{56}$Fe, $^{136}$Xe, and $^{206,207,208}$Pb is presented. An MCNPX library
for simulating the production of low-energy neutrons in the
$^9$Be$(\gamma,n)^8$Be reaction is also presented. Example dark matter detector
calibrations are simulated with the new libraries showing how detector
sensitivity could be overestimated by factors of two by relying on existing
MCNP and Geant4 libraries.


title:
The multivariate Charlier polynomials as matrix elements of the
  Euclidean group representation on oscillator states

abstract:
  A family of multivariate orthogonal polynomials generalizing the standard
(univariate) Charlier polynomials is shown to arise in the matrix elements of
the unitary representation of the Euclidean group E(d) on oscillator states.
These polynomials in d discrete variables are orthogonal on the product of d
Poisson distributions. The accent is put on the d=2 case and the group
theoretical setting is used to obtain the main properties of the polynomials:
orthogonality and recurrence relations, difference equation, raising/lowering
relations, generating function, hypergeometric and integral representations and
explicit expression in terms of standard Charlier and Krawtchouk polynomials.
The approach is seen to extend straightforwardly to an arbitrary number of
variables. The contraction of SO(3) to E(2) is used to show that the bivariate
Charlier polynomials correspond to a limit of the bivariate Krawtchouk
polynomials.


title: NEWS : a new spherical gas detector for very low mass WIMP detection

abstract:
  The main characteristics of a new concept of spherical gaseous detectors,
with some details on its operation are first given. The very low energy
threshold of such detector has led to investigations of its potential
performance for dark matter particle searches, in particular low mass WIMP's :
original methods for energy and fiducial volume calibration and background
rejection are described and preliminary results obtained with a low
radioactivity prototype operated in Laboratoire Souterrain de Modane ("Frejus"
lab) are presented. Typical expected sensitivities in cross section for low
mass WIMP's are also shown, and other applications briefly discussed.


title: Eigenvalue problem for radial potentials in space with SU(2) fuzziness

abstract:
  The eigenvalue problem for radial potentials is considered in a space whose
spatial coordinates satisfy the SU(2) Lie algebra. As the consequence, the
space has a lattice nature and the maximum value of momentum is bounded from
above. The model shows interesting features due to the bound, namely, a
repulsive potential can develop bound-states, or an attractive region may be
forbidden for particles to propagate with higher energies. The exact radial
eigen-functions in momentum space are given by means of the associated
Chebyshev functions. For the radial stepwise potentials the exact energy
condition and the eigen-functions are presented. For a general radial potential
it is shown that the discrete energy spectrum can be obtained in desired
accuracy by means of given forms of continued fractions.


title:
Variational Partitioned Runge-Kutta methods for Lagrangians linear in
  velocities

abstract:
  In this paper we construct higher-order variational integrators for a class
of degenerate systems described by Lagrangians that are linear in velocities.
We analyze the geometry underlying such systems and develop the appropriate
theory for variational integration. Our main observation is that the evolution
takes place on the primary constraint and the 'Hamiltonian' equations of motion
can be formulated as an index-1 differential-algebraic system. We also
construct variational Runge-Kutta methods and analyze their properties. The
general properties of Runge-Kutta methods depend on the 'velocity' part of the
Lagrangian. If the 'velocity' part is also linear in the position coordinate,
then we show that non-partitioned variational Runge-Kutta methods are
equivalent to integration of the corresponding first-order Euler-Lagrange
equations, which have the form of a Poisson system with a constant structure
matrix, and the classical properties of the Runge-Kutta method are retained. If
the 'velocity' part is nonlinear in the position coordinate, we observe a
reduction of the order of convergence, which is typical of numerical
integration of DAEs. We verify our results through numerical experiments for
various dynamical systems.


title: An Osgood's criterion for a semilinear stochastic differential equation

abstract:
  The purpose of this paper is to give an Osgood's criterion for solutions of
semilinear stochastic differential equations of the form $X_{t}=\xi
+\int_{0}^{t}b(s,X_{s})ds+\int_{0}^{t}\sigma (s)X_{s}dW_{s},\ t\geq 0$. Here,
$b$ is a non-negative, non-decreasing by components and continuous random field
and $\sigma $ is a predictable and continuous process. Also we present a
generalization of the so-called Feller's test whenever $\sigma \equiv 1$.


title: Evidence for undamped waves on ohmic materials

abstract:
  The propagation of electromagnetic fields in matter has been the subject of
intensive studies since the discovery of its rich dynamics. Impedance
measurements are one most used technique available to study material properties
as well as electromagnetic devices and circuits. This way, novelties on device
construction and circuit technology associated to new material properties
and/or unusual field dynamics generally rely on results supported by impedance
data. Recent advances on nanostructured materials explore astounding molecular
properties derived from nanoscale levels and apply them to studies foucused on
the generation of new devices. Accordingly, properties inherent to quantum
dynamics can also generate unusual circuit elements, not included on the former
development of the electromagnetic theory. On same footings, advances in field
dynamics could also determine the advent of new technologies, producing
immediate impact on our everyday life. In this work we present the results
obtained by measuring the impedance of single spires and coils of specific
geometry in the MHz range. They demonstrate that a new passive circuit element
was found, which bears out the existence of an as yet unobserved propagation
mode of the electromagnetic fields in matter. Our results also indicates that
this effect is more evident using carbon made spires.


title: Determination of $GL(3)$ Hecke-Maass forms from twisted central values

abstract:
  Suppose $\pi_1$ and $\pi_2$ are two Hecke-Maass cusp forms for
$SL(3,\mathbb{Z})$ such that for all primitive character $\chi$ we have $$
L(\tfrac{1}{2},\pi_1\otimes\chi)=L(\tfrac{1}{2},\pi_2\otimes\chi). $$ Then we
show that $\pi_1=\pi_2$.


title: Chebyshev-Gr\"{u}ss-type inequalities via discrete oscillations

abstract:
  The classical form of Gr\"uss' inequality, first published by G. Gr\"{u}ss in
1935, gives an estimate of the difference between the integral of the product
and the product of the integrals of two functions. In the subsequent years,
many variants of this inequality appeared in the literature. The aim of this
paper is to introduce a different approach, presenting a new
Chebyshev-Gr\"uss-type inequality and applying it to different well-known
linear, not necessarily positive, operators. Some conjectures are presented as
well. We also compare the new inequalities with some older results. This new
approach gives better estimates in some cases than the ones already known.


title:
When is it Biased? Assessing the Representativeness of Twitter's
  Streaming API

abstract:
  Twitter has captured the interest of the scientific community not only for
its massive user base and content, but also for its openness in sharing its
data. Twitter shares a free 1% sample of its tweets through the "Streaming
API", a service that returns a sample of tweets according to a set of
parameters set by the researcher. Recently, research has pointed to evidence of
bias in the data returned through the Streaming API, raising concern in the
integrity of this data service for use in research scenarios. While these
results are important, the methodologies proposed in previous work rely on the
restrictive and expensive Firehose to find the bias in the Streaming API data.
In this work we tackle the problem of finding sample bias without the need for
"gold standard" Firehose data. Namely, we focus on finding time periods in the
Streaming API data where the trend of a hashtag is significantly different from
its trend in the true activity on Twitter. We propose a solution that focuses
on using an open data source to find bias in the Streaming API. Finally, we
assess the utility of the data source in sparse data situations and for users
issuing the same query from different regions.


title:
Expressing the entropy of lattice systems as sums of conditional
  entropies

abstract:
  Whether a system is to be considered complex or not depends on how one
searches for correlations. We propose a general scheme for calculation of
entropies in lattice systems that has high flexibility in how correlations are
successively taken into account. Compared to the traditional approach for
estimating the entropy density, in which successive approximations builds on
step-wise extensions of blocks of symbols, we show that one can take larger
steps when collecting the statistics necessary to calculate the entropy density
of the system. In one dimension this means that, instead of a single sweep over
the system in which states are read sequentially, one take several sweeps with
larger steps so that eventually the whole lattice is covered. This means that
the information in correlations is captured in a different way, and in some
situations this will lead to a considerably much faster convergence of the
entropy density estimate as a function of the size of the configurations used
in the estimate. The formalism is exemplified with both an example of a free
energy minimisation scheme for the two-dimensional Ising model, and an example
of increasingly complex spatial correlations generated by the time evolution of
elementary cellular automaton rule 60.


title: Spaces of generalized splines over T-meshes

abstract:
  We consider a class of non-polynomial spline spaces over T-meshes, that is,
of spaces locally spanned both by polynomial and by suitably-chosen
non-polynomial functions, which we will refer to as generalized splines over
T-meshes. For such spaces, we provide, under certain conditions, a dimension
formula and a basis based on the notion of minimal determining set. We
explicitly examine some relevant cases, which enjoy a noteworthy behaviour with
respect to differentiation and integration; finally, we also study the
approximation power of the just constructed spline spaces.


title: Polar structures in late-type galaxies

abstract:
  A common point of view is that stable polar structures are mainly present in
the E/S0 early-type galaxies lacking dense gas in their host disks. However,
nuclear, as well as external polar rings and disks also exist in the late-type
hosts, including gas-rich dwarf galaxies. Using the 3D spectroscopic
observations of these objects we can derive the rotation properties of the gas
components separately in the main and polar planes. The most detailed picture
of the gas kinematics and mass distribution properties could be obtained from
the combination of optical (H II) and radio (H I) data sets. I briefly review
the results of such studies, including the observations of the direct
interaction between the multi-spin gas components.


title:
From the Samuelson Volatility Effect to a Samuelson Correlation Effect:
  Evidence from Crude Oil Calendar Spread Options

abstract:
  We introduce a multi-factor stochastic volatility model based on the
CIR/Heston stochastic volatility process. In order to capture the Samuelson
effect displayed by commodity futures contracts, we add expiry-dependent
exponential damping factors to their volatility coefficients. The pricing of
single underlying European options on futures contracts is straightforward and
can incorporate the volatility smile or skew observed in the market. We
calculate the joint characteristic function of two futures contracts in the
model in analytic form and use the one-dimensional Fourier inversion method of
Caldana and Fusai (JBF 2013) to price calendar spread options. The model leads
to stochastic correlation between the returns of two futures contracts. We
illustrate the distribution of this correlation in an example. We then propose
analytical expressions to obtain the copula and copula density directly from
the joint characteristic function of a pair of futures. These expressions are
convenient to analyze the term-structure of dependence between the two futures
produced by the model. In an empirical application we calibrate the proposed
model to volatility surfaces of vanilla options on WTI. In this application we
provide evidence that the model is able to produce the desired stylized facts
in terms of volatility and dependence. In a separate appendix, we give guidance
for the implementation of the proposed model and the Fourier inversion results
by means of one and two-dimensional FFT methods.


title:
Fitting N$^{3}$LO pseudopotentials through central plus tensor Landau
  parameters

abstract:
  Landau parameters determined from phenomenological finite-range interactions
are used to get an estimation of N$^3$LO pseudopotentials parameters. The
parameter sets obtained in this way are shown to lead to consistent results
concerning saturation properties. The uniqueness of this procedure is
discussed, and an estimate of the error induced by the truncation at N$^3$LO is
given.


title: Radial oscillations of neutral and charged hybrid stars

abstract:
  We construct stellar models of hadron stars and hybrid stars and calculate
the frequencies of their lowest radial mode of vibration. Chandrasekhar's
equation for radial oscillations is generalized for stars with internal
electric fields and earlier versions of that generalization are simplified. For
the hybrid stars a Gibbs construction is employed. It is found that the
softening of the equation of state associated with the presence of deconfined
quarks reduces the oscillation frequency. We show that a slight charge
inbalance should lead to increased maximum mass, decreased central density and
lower oscillation frequencies.


title: Splitting a critical spin chain

abstract:
  We study a quench protocol that conserves the entanglement spectrum of a
bipartition of a quantum system. As an example we consider the splitting of a
critical Ising chain in two chains, and compare it with the well known case of
joining of two chains. We show that both the out of equilibrium time evolution
of global properties and the equilibrium regime after the quench of local
properties are different in the two scenarios. Since the two quenches only
differ in the presence/absence of the conservation of the entanglement
spectrum, our results suggest that this conservation plays a fundamental role
in both the out-of-equilibrium dynamics and the subsequent equilibration
mechanism. We discuss the relevance of our results in the context of quantum
simulators.

categories: cond-mat.str-el cond-mat.quant-gas cond-mat.stat-mech quant-ph


title: Quantum Randomness Certified by the Uncertainty Principle

abstract:
  We present an efficient method to extract the amount of true randomness that
can be obtained by a Quantum Random Number Generator (QRNG). By repeating the
measurements of a quantum system and by swapping between two mutually unbiased
bases, a lower bound of the achievable true randomness can be evaluated. The
bound is obtained thanks to the uncertainty principle of complementary
measurements applied to min- and max- entropies. We tested our method with two
different QRNGs, using a train of qubits or ququart, demonstrating the
scalability toward practical applications.


title:
Equations of motion for two-body problem according to an observer inside
  the gravitational field

abstract:
  In this paper we consider equations of motion for 2-body problem according to
an observer close to one of the gravitational bodies. The influence of the
Thomas precession of the observer's frame has an important role. The equations
of motion are based on a nonlinear connection modified by the action of an
orthogonal tensor which synchronizes the 4-velocities of the considered two
bodies. Finally we present periastron shift according to an observer inside the
gravitational field, using the orthonormal coordinates. This is different
approach than that used in General Relativity where the periastron shift is
only given as observed far from the massive bodies.


title:
Robust construction of entangled coherent GHZ and W states in a cavity
  QED system

abstract:
  By exploiting a system of three distant cavities, we propose a scheme for
constructing tripartite entangled coherent GHZ and W states which are robust
due to the photon losses in the cavities. Each of cavities is doped with a
semiconductor quantum dot. By the dynamics, the excitonic modes of quantum dots
are enabled to exhibit entan-gled coherent GHZ and W states. Apart from the
exciton losses, the master equation approach shows that when the populations of
the field modes in the cavities are negli-gible the destruction of entanglement
due to decoherence arises from photon losses, is effectively suppressed.


title: The Structure of Qubit Unextendible Product Bases

abstract:
  Unextendible product bases have been shown to have many important uses in
quantum information theory, particularly in the qubit case. However, very
little is known about their mathematical structure beyond three qubits. We
present several new results about qubit unextendible product bases, including a
complete characterization of all four-qubit unextendible product bases, which
we show there are exactly 1446 of. We also show that there exist p-qubit UPBs
of almost all sizes less than $2^p$.


title:
Catastrophic shifts and lethal thresholds in a propagating front model
  of unstable tumour progression

abstract:
  Unstable dynamics characterizes the evolution of most solid tumors. Because
of an increased failure of maintaining genome integrity, a cumulative increase
in the levels of gene mutation and loss is observed. Previous work suggests
that instability thresholds to cancer progression exist, defining phase
transition phenomena separating tumor-winning scenarios from tumor extinction
or coexistence phases. Here we present an integral equation approach to the
quasispecies dynamics of unstable cancer. The model exhibits two main phases,
characterized by either the success or failure of cancer tissue. Moreover, the
model predicts that tumor failure can be due to either a reduced selective
advantage over healthy cells or excessive instability. We also derive an
approximate, analytical solution that predicts the front speed of aggressive
tumor populations on the instability space.


title:
Dispersion Relation of Longitudinal Waves in Liquid He-4 in the
  Framework of Quantum Macroscopic Equations derived from Bohm's Potential

abstract:
  He-4 is known to become superfluid at very low temperatures. This effect is
now generally accepted to be connected with BEC (Bose-Einstein Condensation).
The dispersion relation of pressure waves in superfluid He-4 has been
determined at 1.1 {\deg}K by Yarnell et al., and exhibits a non monotonic
behavior - with a maximum and a minimum - usually explained in terms of
excitations called rotons, introduced by Landau. In the present work an attempt
is made to describe the phenomenon within the bohmian interpretation of QM. To
this end, the effects of the intermolecular potential, taken to be essentially
of the Lennard-Jones type modified to account for molecule finiteness, are
included as a Vlasov-type self-consistent field. A dispersion relation is
found, that is in quite good agreement with Yarnell's curve.
  Keywords: Bohm potential; Intermolecular potential; Dispersion relation;
Superfluid He-4; First sound.
  PACS: 05.30.Jp; 05.20.Dd; 03.75.Kk; 67.25.dt


title:
Loopy annealing belief propagation for vertex cover and matching:
  convergence, LP relaxation, correctness and Bethe approximation

abstract:
  For the minimum cardinality vertex cover and maximum cardinality matching
problems, the max-product form of belief propagation (BP) is known to perform
poorly on general graphs. In this paper, we present an iterative loopy
annealing BP (LABP) algorithm which is shown to converge and to solve a Linear
Programming relaxation of the vertex cover or matching problem on general
graphs. LABP finds (asymptotically) a minimum half-integral vertex cover (hence
provides a 2-approximation) and a maximum fractional matching on any graph. We
also show that LABP finds (asymptotically) a minimum size vertex cover for any
bipartite graph and as a consequence compute the matching number of the graph.
Our proof relies on some subtle monotonicity arguments for the local iteration.
We also show that the Bethe free entropy is concave and that LABP maximizes it.
Using loop calculus, we also give an exact (also intractable for general
graphs) expression of the partition function for matching in term of the LABP
messages which can be used to improve mean-field approximations.

categories: cs.DM cs.DS cs.IT math-ph math.IT math.MP math.PR


title:
A combined theoretical and experimental study of the influence of
  different anion ratios on lithium ion dynamics in ionic liquids

abstract:
  In this paper we have investigated via experimental and simulations
techniques the transport properties, in terms of total ionic conductivity and
ion diffusion coefficients, of ionic liquids and lithium salt mixtures composed
of two anions, bis(fluorosulfonyl)imide (FSI) and
bis(trifluoromethanesulfonyl)imide (TFSI), and two cations,
N-ethyl-N-methylimidazolium (emim) and lithium. The comparison of the
experimental results with the simulations shows an exceptional agreement over a
wide temperature range. Of particular interest is the high agreement achieved
at lower temperature, which is a result of the extended simulation length of,
at least, a factor of 5 compared with previous work. The results show as the
addition of TFSI favor the formation of lithium dimers (Li+ - TFSI- - Li+). A
closer analysis of such dimers shows that involved lithium ions move nearly as
fast as single lithium ions although they have a different coordination and
much slower TFSI exchange rates.


title: Pulsar Timing Arrays and the cosmological constant

abstract:
  In this talk I review how a non-zero cosmological constant $\Lambda$ affects
the propagation of gravitational waves and their detection in pulsar timing
arrays (PTA). If $\Lambda\neq 0$ it turns out that waves are anharmonic in
cosmological Friedmann-Robertson- Walker coordinates and although the amount of
anharmonicity is very small it leads to potentially measurable effects. The
timing residuals induced by gravitational waves in PTA would show a peculiar
angular dependence with a marked enhancement around a particular value of the
angle subtended by the source and the pulsars. This angle depends mainly on the
actual value of the cosmological constant and the distance to the source.
Preliminary estimates indicate that the enhancement can be rather notorious for
supermassive black hole mergers and in fact it could facilitate the first
direct detection of gravitational waves while at the same time representing a
`local' measurement of $\Lambda$.


title: The Raychaudhuri equation in homogeneous cosmologies

abstract:
  In this work we address the issue of studying the conditions required to
guarantee the Focusing Theorem for both null and timelike geodesic congruences
by using the Raychaudhuri equation. In particular we study the case of
Friedmann-Robertson-Walker as well as more general Bianchi Type I spacetimes.
The fulfillment of the Focusing Theorem is mandatory in small scales since it
accounts for the attractive character of gravity. However, the Focusing Theorem
is not satisfied at cosmological scales due to the measured negative
deceleration parameter. The study of the conditions needed for congruences
convergence is not only relevant at the fundamental level but also to derive
the viability conditions to be imposed on extended theories of gravity
describing the different expansion regimes of the universe. We illustrate this
idea for f(R) gravity theories.


title: Some examples of non-rectifiable, repetitive Delone sets

abstract:
  We construct examples of Delone sets of the plane (that is, discrete subsets
that are uniformly separated and coarsely dense) that are repetitive (each
patch of the set appears in every large-enough ball) though non-rectifiable
(i.e. non bi-Lipschitz equivalent to the standard lattice). More generally, we
construct such a set so that the translation action on the closure of its orbit
has any prescribed Choquet simplex as its set of invariant probability measures
(in particular, we provide uniquely ergodic examples). The construction relies
on classical examples of Burago-Kleiner and McMullen, for which we give pure
combinatorial (an effective) versions that have interest by themselves.


title: On Linkedness of Cartesian Product of Graphs

abstract:
  We study linkedness of Cartesian product of graphs and prove that the product
of an $a$-linked and a $b$-linked graphs is $(a+b-1)$-linked if the graphs are
sufficiently large. Further bounds in terms of connectivity are shown. We
determine linkedness of product of paths and product of cycles.


title: On Path-Pairability of Cartesian Product of Complete Bipartite Graphs

abstract:
  We study inheritance of path-pairability in the Cartesian product of graphs,
and prove different (such as additive and multiplicative) inheritance patterns
of path-pairability, depending on the size of the Cartesian product. We present
path-pairable graph families, that improve the known upper bound on the minimal
maximum degree of a path-pairable graph. Further results and open questions
about path-pairability are also presented.


title:
Water softening by single-bowl ion exchange filter efficiency estimate
  and improvement

abstract:
  The article presents results of experimental investigations of the water
softener in a laboratory installation of uninterruptible countercurrent ion
exchange filter, which has a movable layer of ion exchange material. The
installation provides for two simultaneous processes: counter ion sorption and
regeneration of the sorbent with the processing capability of the sorbent in
the regeneration zone by ultrasonic radiation.


title: Note on the Diameter of Path-Pairable Graphs

abstract:
  A graph on $2k$ vertices is path-pairable if for any pairing of the vertices
the pairs can be joined by edge-disjoint paths. The so far known families of
path-pairable graphs have diameter of length at most 3. In this paper we
present an infinite family of path-pairable graphs with diameter
$d(G)=O(\sqrt{n})$ where $n$ denotes the number of vertices of the graph. We
prove that our example is extremal up to a constant factor.


title: On the Origin of Young Stars at the Galactic Center

abstract:
  The center of our galaxy is home to a massive black hole, SgrA*, and a
nuclear star cluster containing stellar populations of various ages. While the
late type stars may be too old to have retained memory of their initial orbital
configuration, and hence formation mechanism, the kinematics of the early type
stars should reflect their original distribution. In this contribution we
present a new statistic which uses directly-observable kinematical stellar data
to infer orbital parameters for stellar populations, and is capable of
distinguishing between different origin scenarios. We use it on a population of
B-stars in the Galactic center that extends out to large radii (0.5 pc) from
the massive black hole. We find that the high K-magnitude population form an
eccentric distribution, suggestive of a Hills binary-disruption origin.


title:
Hydrodynamic Burnett equations for inelastic Maxwell models of granular
  gases

abstract:
  The hydrodynamic Burnett equations and the associated transport coefficients
are exactly evaluated for generalized inelastic Maxwell models. In those
models, the one-particle distribution function obeys the inelastic Boltzmann
equation, with a velocity-independent collision rate proportional to the
$\gamma$ power of the temperature. The pressure tensor and the heat flux are
obtained to second order in the spatial gradients of the hydrodynamic fields
with explicit expressions for all the Burnett transport coefficients as
functions of $\gamma$, the coefficient of normal restitution, and the
dimensionality of the system. Some transport coefficients that are related in a
simple way in the elastic limit become decoupled in the inelastic case. As a
byproduct, existing results in the literature for three-dimensional elastic
systems are recovered, and a generalization to any dimension of the system is
given. The structure of the present results is used to estimate the Burnett
coefficients for inelastic hard spheres.


title:
Gravitational wave solutions of quadratic curvature gravity using a null
  coframe formulation

abstract:
  Quadratic curvature gravity equations are projected to a complex null coframe
by using the algebra of exterior forms and expressed in terms of the spinor
quantities defined originally by Newman and Penrose. As an application, a new
family of impulsive gravitational wave solutions propagating in various type D
backgrounds is introduced.


title: Detecting the First Stars and Black Holes with 21-cm Cosmology

abstract:
  Understanding the formation and evolution of the first stars and galaxies
represents one of the most exciting frontiers in astronomy. Since the universe
was filled with neutral hydrogen at early times, the most promising method for
observing the epoch of the first stars is using the prominent 21-cm spectral
line of the hydrogen atom. Current observational efforts are focused on the
reionization era (cosmic age t~500 Myr), with earlier times considered much
more challenging. However, the next frontier of even earlier galaxy formation
(t~200 Myr) is emerging as a promising observational target. This is made
possible by a recently noticed effect of a significant relative velocity
between the baryons and dark matter at early times. The velocity difference
significantly suppresses star formation. The spatial variation of this
suppression enhances large-scale clustering and produces a prominent cosmic web
on 100 comoving Mpc scales in the 21-cm intensity distribution. This structure
makes it much more feasible for radio astronomers to detect these early stars,
and should drive a new focus on this era, which is rich with little-explored
astrophysics.


title: CMB statistical anisotropy from noncommutative gravitational waves

abstract:
  Primordial statistical anisotropy is a key indicator to investigate early
Universe models and has been probed by the cosmic microwave background (CMB)
anisotropies. In this paper, we examine tensor-mode CMB fluctuations generated
from anisotropic gravitational waves, parametrised by $P_h({\bf k}) =
P_h^{(0)}(k) [ 1 + \sum_{LM} f_L(k) g_{LM} Y_{LM} (\hat{\bf k}) ]$, where
$P_h^{(0)}(k)$ is the usual scale-invariant power spectrum. Such anisotropic
tensor fluctuations may arise from an inflationary model with noncommutativity
of fields. It is verified that in this model, an isotropic component and a
quadrupole asymmetry with $f_0(k) = f_2(k) \propto k^{-2}$ are created and
hence highly red-tilted off-diagonal components arise in the CMB power spectra,
namely $\ell_2 = \ell_1 \pm 2$ in $TT$, $TE$, $EE$ and $BB$, and $\ell_2 =
\ell_1 \pm 1$ in $TB$ and $EB$. We find that B-mode polarisation is more
sensitive to such signals than temperature and E-mode polarisation due to the
smallness of large-scale cosmic variance and we can potentially measure $g_{00}
= 30$ and $g_{2M} = 58$ at 68% CL in a cosmic-variance-limited experiment. Such
a level of signal may be measured in a PRISM like experiment, while the
instrumental noise contaminates it in the $Planck$ experiment. These results
imply that it is impossible to measure the noncommutative parameter if it is
small enough for the perturbative treatment to be valid. Our formalism and
methodology for dealing with the CMB tensor statistical anisotropy are general
and straightforwardly applicable to other early Universe models.


title: Remarks on Realizing Inflation in String and Particle Physics Models

abstract:
  The recent measurements of cosmological parameters by the Planck
collaboration favors inflationary models with a redshifted spectrum and a very
low tensor-to-scalar ratio. Two well-studied scenarios in the particle
physics/string theory literature -- inflection point and Starobinsky inflation
-- are in good agreement with these data. In these proceedings, we report on
general studies of these two scenarios. We discuss similarities in their
structure which, we argue, arise from a common mechanism: degenerate critical
point of the potential. In particular, we emphasize their ability to support a
possible primordial explanation for the anomalous suppression of the power
spectrum at large scales.


title: Conormal problem of higher-order parabolic systems

abstract:
  The paper is a comprehensive study of the $L_p$ and the Schauder estimates
for higher-order divergence type parabolic systems with discontinuous
coefficients in the half space and cylindrical domains with conormal derivative
boundary condition. For the $L_p$ estimates, we assume that the leading
coefficients are only bounded measurable in the $t$ variable and $VMO$ with
respect to $x$. We also prove the Schauder estimates in two situations: the
coefficients are H\"older continuous only in the $x$ variable; the coefficients
are H\"older continuous in both variables.


title: Multi-mode storage and retrieval of microwave fields in a spin ensemble

abstract:
  A quantum memory at microwave frequencies, able to store the state of
multiple superconducting qubits for long times, is a key element for quantum
information processing. Electronic and nuclear spins are natural candidates for
the storage medium as their coherence time can be well above one second.
Benefiting from these long coherence times requires to apply the refocusing
techniques used in magnetic resonance, a major challenge in the context of
hybrid quantum circuits. Here we report the first implementation of such a
scheme, using ensembles of nitrogen-vacancy (NV) centres in diamond coupled to
a superconducting resonator, in a setup compatible with superconducting qubit
technology. We implement the active reset of the NV spins into their ground
state by optical pumping and their refocusing by Hahn echo sequences. This
enables the storage of multiple microwave pulses at the picoWatt level and
their retrieval after up to $35 \mu$s, a three orders of magnitude improvement
compared to previous experiments.


title:
Magnetoresistance Induced by Rare Strong Scatterers in a High Mobility
  2DEG

abstract:
  We observe a strong negative magnetoresistance at non-quantizing magnetic
fields in a high-mobility two-dimensional electron gas (2DEG). This strong
negative magnetoresistance consists of a narrow peak around zero magnetic field
and a huge magnetoresistance at larger fields. The peak shows parabolic
magnetic field dependence and is attributed to the interplay of smooth disorder
and rare strong scatterers. We identify the rare strong scatterers as
macroscopic defects in the material and determine their density from the peak
curvature.


title:
Exploiting Causality for Selective Belief Filtering in Dynamic Bayesian
  Networks

abstract:
  Dynamic Bayesian networks (DBNs) are a general model for stochastic processes
with partially observed states. Belief filtering in DBNs is the task of
inferring the belief state (i.e. the probability distribution over process
states) based on incomplete and noisy observations. This can be a hard problem
in complex processes with large state spaces. In this article, we explore the
idea of accelerating the filtering task by automatically exploiting causality
in the process. We consider a specific type of causal relation, called
passivity, which pertains to how state variables cause changes in other
variables. We present the Passivity-based Selective Belief Filtering (PSBF)
method, which maintains a factored belief representation and exploits passivity
to perform selective updates over the belief factors. PSBF produces exact
belief states under certain assumptions and approximate belief states
otherwise, where the approximation error is bounded by the degree of
uncertainty in the process. We show empirically, in synthetic processes with
varying sizes and degrees of passivity, that PSBF is faster than several
alternative methods while achieving competitive accuracy. Furthermore, we
demonstrate how passivity occurs naturally in a complex system such as a
multi-robot warehouse, and how PSBF can exploit this to accelerate the
filtering task.


title:
The four-dimensional Martinez Alonso--Shabat equation: reductions and
  nonlocal symmetries

abstract:
  We consider the four-dimensional integrable Martinez Alonso--Shabat equation,
and list three integrable three-dimensional reductions thereof. We also present
a four-dimensional integrable modified Martinez Alonso--Shabat equation
together with its Lax pair.
  We also construct an infinite hierarchy of commuting nonlocal symmetries (and
not just the shadows, as it is usually the case in the literature) for the
Martinez Alonso--Shabat equation.


title: Robin Schwarz algorithm for the NICEM Method: the Pq finite element case

abstract:
  In Gander et al. [2004] we proposed a new non-conforming domain decomposition
paradigm, the New Interface Cement Equilibrated Mortar (NICEM) method, based on
Schwarz type methods that allows for the use of Robin interface conditions on
non-conforming grids. The error analysis was done for P1 finite elements, in 2D
and 3D. In this paper, we provide new numerical analysis results that allow to
extend this error analysis in 2D for piecewise polynomials of higher order and
also prove the convergence of the iterative algorithm in all these cases.


title: Performance Rescaling of Complex Networks

abstract:
  Recent progress in network topology modeling [1], [2] has shown that it is
possible to create smaller-scale replicas of large complex networks, like the
Internet, while simultaneously preserving several important topological
properties. However, the constructed replicas do not include notions of
capacities and latencies, and the fundamental question of whether smaller
networks can reproduce the performance of larger networks remains unanswered.
We address this question in this letter, and show that it is possible to
predict the performance of larger networks from smaller replicas, as long as
the right link capacities and propagation delays are assigned to the replica's
links. Our procedure is inspired by techniques introduced in [2] and combines a
time-downscaling argument from [3]. We show that significant computational
savings can be achieved when simulating smaller-scale replicas with TCP and UDP
traffic, with simulation times being reduced by up to two orders of magnitude.

categories: cs.NI cond-mat.stat-mech cs.SI physics.soc-ph


title:
The Be-test in the Li-rich star \#1657 of NGC 6397: evidence for
  Li-flash in RGB stars?

abstract:
  The Li-rich turn-off star in the globular cluster NGC 6397 could represent
the smoking gun for some very rare episode of Li enrichment in globular
clusters. We aim to understand the nature of the Li enrichment by performing a
spectroscopic analysis of the star, in particular of its beryllium (Be)
abundance, and by investigating its binary nature. We observe the near UV
region where the Beii resonance doublet and the NH bands are located. We could
not detect the Beii lines and derive an upper limit of log (Be/H)< -12.2, that
is consistent with the Be observed in other stars of the cluster. We could
detect a weak G-band, which implies a mild carbon enhancement
[C/Fe]$+0.4\pm0.2$. We could not detect the UV NH band, and we derive an upper
limit [N/Fe]$< 0.0$. For oxygen we could notdetect any of the near UV OH lines,
which implies that oxygen cannot be strongly enhanced in this star. This is
consistent with the detection of the Oi triplet at 777nm, which is consistent
with [O/Fe]~0.5. Combining the UVES and Mike data, we could not detect any
variation in the radial velocity greater than 0.95 kms$^{-1}$ over 8 years. The
chemical composition of the star strongly resembles that of `first generation'
NGC6397 stars, with the huge Li as the only deviating abundance. Not detecting
Be rules out two possible explanations of the Li overabundance: capture of a
substellar body and spallation caused by a nearby type II SNe. Discrepancies
are also found with respect to other accretion scenarios,except for
contamination by the ejecta of a star that has undergone the RGB Li-flash.


title:
Comparing multiplier ideals to test ideals on numerically Q-Gorenstein
  varieties

abstract:
  We show that the reduction to positive characteristic of the multiplier ideal
in the sense of de Fernex and Hacon agrees with the test ideal for infinitely
many primes, assuming that the variety is numerically Q-Gorenstein. It follows,
in particular, that this reduction property holds in dimension 2 for all normal
surfaces.


title: B-Meson Decays into Final States with a tau Lepton

abstract:
  Decays of B mesons into final states containing a tau lepton are sensitive to
new charged-current interactions that break lepton-flavor universality. These
decays have been studied only at e+e- colliders, where the low-background
environment and well-known initial state make it possible to observe small
signals with undetectable neutrinos. In particular, the large data samples of
the B factories and recent advances in techniques for full-event reconstruction
have led to evidence for the decay B --> tau nu and unambiguous observation of
the decays B --> D(*)tau nu. These results have led to exclusion of large
regions of the parameter space for a variety of new-physics models.
Furthermore, the branching fraction for B --> D(*)tau nu has been measured to
be higher than the standard-model expectation by at least 3.4 standard
deviations, making this an interesting topic for further research. This letter
reviews the theoterical and experimental status of this topic, summarizing the
results at this time and outlining the path for further improvements.


title: A Lower Bound for Generalized Dominating Numbers

abstract:
  We show a new proof for the fact that when $\kappa$ and $\lambda$ are
infinite cardinals satisfying $\lambda ^ \kappa = \lambda$, the cofinality of
the set of all functions from $\lambda$ to $\kappa$ ordered by everywhere
domination is $2^\lambda$. An earlier proof was a consequence of a result about
independent families of functions. The new proof follows directly from the main
theorem we present: for every $A \subseteq \lambda$ there is a function $f:
{^\kappa \lambda} \to \kappa$ such that whenever $M$ is a transitive model of
$\textrm{ZF}$ such that ${^\kappa \lambda} \subseteq M$ and some $g: {^\kappa
\lambda} \to \kappa$ in $M$ dominates $f$, then $A \in M$. That is,
"constructibility can be reduced to domination".


title:
Measurement of Vacuum Pressure with a Magneto-Optical Trap: a
  Pressure-Rise Method

abstract:
  The lifetime of an atom trap is often limited by the presence of residual
background gases in the vacuum chamber. This leads to the lifetime being
inversely proportional to the pressure. Here we use this dependence to estimate
the pressure and to obtain pressure rate-of-rise curves, which are commonly
used in vacuum science to evaluate the performance of a system. We observe
different rates of pressure increase in response to different levels of
outgassing in our system. Therefore we suggest that this is a sensitive method
which will be useful in applications of cold atom systems, in particular where
the inclusion of a standard vacuum gauge is impractical.


title: The chord-length probability density of the regular octahedron

abstract:
  The chord length probability density of the regular octahedron is explicitly
evaluated throughout its full range of distances by separating it into three
contributions respectively due to the pairs of facets opposite to each other or
sharing an edge or a vertex.


title: Renormalization of Null Wilson Lines in EQCD

abstract:
  Radiation and energy loss of a light, high-energy parton in a perturbative
Quark-Gluon Plasma is controlled by transverse momentum exchange. The
troublesome infrared contributions to transverse momentum exchange can be
computed on the lattice using dimensional reduction to EQCD. However a novel
extended operator, the Null Wilson Line of EQCD, is involved. We compute the
renormalization properties of this object's lattice implementation to
next-to-leading order, which should facilitate its efficient calculation on the
lattice.


title: Superfield theories on $S^3$ and their localization

abstract:
  We consider the superfield formulation of supersymmetric gauge and matter
field theories on a three-dimensional sphere with rigid ${\cal N}=2$
supersymmetry, as well as with ${\cal N}> 2$. The construction is based on a
supercoset $SU(2|1)/U(1)$ containing $S^3$ as the bosonic subspace. We derive
an explicit form of $SU(2|1)/U(1)$ supervielbein and covariant derivatives, and
use them to construct classical superfield actions for gauge and matter
supermultiplets in this superbackground. We then apply superfield methods for
computing one-loop partition functions of these theories and demonstrate how
the localization technique works directly in the superspace.


title: Training population selection for (breeding value) prediction

abstract:
  Training population selection for genomic selection has captured a great deal
of interest in animal and plant breeding. In this article, we derive a
computationally efficient statistic to measure the reliability of estimates of
genetic breeding values for a fixed set of genotypes based on a given training
set of genotypes and phenotypes. We adopt a genetic algorithm scheme to find a
training set of certain size from a larger set of candidate genotypes that
optimizes this reliability measure. Our results show that, compared to a random
sample of the same size, phenotyping individuals selected by our method results
in models with better accuracies. We implement the proposed training selection
methodology on four data sets, namely, the arabidopsis, wheat, rice and the
maize data sets. Our results indicate that dynamic model building process which
uses genotypes of the individuals in the test sample into account while
selecting the training individuals improves the performance of GS models.


title: On nonlocal Cahn-Hilliard-Navier-Stokes systems in two dimensions

abstract:
  We consider a diffuse interface model which describes the motion of an
incompressible isothermal mixture of two immiscible fluids. This model consists
of the Navier-Stokes equations coupled with a convective nonlocal Cahn-Hilliard
equation. Several results were already proven by two of the present authors.
However, in the two-dimensional case, the uniqueness of weak solutions was
still open. Here we establish such a result even in the case of degenerate
mobility and singular potential. Moreover, we show the strong-weak uniqueness
in the case of viscosity depending on the order parameter, provided that either
the mobility is constant and the potential is regular or the mobility is
degenerate and the potential is singular. In the case of constant viscosity, on
account of the uniqueness results we can deduce the connectedness of the global
attractor whose existence was obtained in a previous paper. The uniqueness
technique can be adapted to show the validity of a smoothing property for the
difference of two trajectories which is crucial to establish the existence of
an exponential attractor. The latter is established even in the case of
variable viscosity, constant mobility and regular potential.


title: Capitulation des $2$-classes d'id\'eaux de type $(2, 4)$

abstract:
  In this paper, we establish two main results which give conditions necessary
and sufficient for a $ 2 $-group metabelian such that $G/G'$ is of type $(2,
4)$ either metacyclic or not. If $G$ is the Galois group of
$\mathbf{k}_2^{(2)}/\mathbf{k}$ where $\mathbf{k}_2^{(2)}$ is the the Second
Hilbert $2$-class field of a number field $\mathbf{k}$, we will get results on
the problem of capitulation.


title: Wolfe's theorem for weakly differentiable cochains

abstract:
  A fundamental theorem of Wolfe isometrically identifies the space of flat
differential forms of dimension $m$ in $\mathbb{R}^n$ with the space of flat
$m$-cochains, that is, the dual space of flat chains of dimension $m$ in
$\mathbb{R}^n$. The main purpose of the present paper is to generalize Wolfe's
theorem to the setting of Sobolev differential forms and Sobolev cochains in
$\mathbb{R}^n$. A suitable theory of Sobolev cochains has recently been
initiated by the second and third author. It is based on the concept of upper
norm and upper gradient of a cochain, introduced in analogy with
Heinonen-Koskela's concept of upper gradient of a function.


title:
Sudden Photospheric Motion and Sunspot Rotation Associated with the X2.2
  Flare on 2011 February 15

abstract:
  The Helioseismic and Magnetic Imager provides 45 s cadence intensity images
and 720 s cadence vector magnetograms. These unprecedented high-cadence and
high-resolution data give us a unique opportunity to study the change of
photospheric flows and sunspot rotations associated with flares. By using the
differential affine velocity estimator method and the Fourier local correlation
tracking method separately, we calculate velocity and vorticity of photospheric
flows in the flaring NOAA AR 11158, and investigate their temporal evolution
around the X2.2 flare on 2011 February 15. It is found that the shear flow
around the flaring magnetic polarity inversion line exhibits a sudden decrease,
and both of the two main sunspots undergo a sudden change in rotational motion
during the impulsive phase of the flare. These results are discussed in the
context of the Lorentz-force change that was proposed by Hudson et al. (2008)
and Fisher et al. (2012). This mechanism can explain the connections between
the rapid and irreversible photospheric vector magnetic field change and the
observed short-term motions associated with the flare. In particular, the
torque provided by the horizontal Lorentz force change agrees with what is
required for the measured angular acceleration.


title:
Convergence of U-statistics indexed by a random walk to stochastic
  integrals of a Levy sheet

abstract:
  We establish limit theorems for U-statistics indexed by a random walk on Z^d
and we express the limit in terms of some Levy sheet Z(s,t). Under some
hypotheses, we prove that the limit process is Z(t,t) if the random walk is
transient or null-recurrent ant that it is some stochastic integral with
respect to Z when the walk is positive recurrent. We compare our results with
results for random walks in random scenery.


title: Structure of Superheavy Nuclei Along Element 115 Decay Chains

abstract:
  A recent high-resolution $\alpha$, $X$-ray, and $\gamma$-ray
coincidence-spectroscopy experiment offered first glimpse of excitation schemes
of isotopes along $\alpha$-decay chains of $Z=115$. To understand these
observations and to make predictions about shell structure of superheavy nuclei
below $^{288}115$, we employ two complementary mean-field models:
self-consistent Skyrme Energy Density Functional approach and the
macroscopic-microscopic Nilsson model. We discuss the spectroscopic information
carried by the new data. In particular, candidates for the experimentally
observed $E1$ transitions in $^{276}$Mt are proposed. We find that the presence
and nature of low-energy $E1$ transitions in well-deformed nuclei around
$Z=110, N=168$ strongly depends on the strength of the spin-orbit coupling;
hence, it provides an excellent constraint on theoretical models of superheavy
nuclei. To clarify competing theoretical scenarios, an experimental search for
$E1$ transitions in odd-$A$ systems $^{275,277}$Mt, $^{275}$Hs, and $^{277}$Ds
is strongly recommended.


title: In the footsteps of Ebenezer Porter Mason and his nebulae

abstract:
  In 1839 Ebenezer Porter Mason (1819-1840) produced detailed drawings of the
Omega Nebula (M17), the Trifid Nebula (M20) and the eastern part of the Veil
Nebula (NGC 6992 and 6995). He used a 12-inch (30 cm) reflector that he and his
friends had built at Yale College, which at the time was the largest telescope
in the USA. The drawings were remarkable for their accuracy and for his
adoption of a new technique for delineating gradients in nebulosity using
isophotes, or lines of equal brightness. This paper reviews his life and his
observations, comparing his results with those of the modern amateur
astronomer.


title:
Neutron spectroscopic factors of $^{55}$Ni hole-states from (p,d)
  transfer reactions

abstract:
  Spectroscopic information has been extracted on the hole-states of $^{55}$Ni,
the least known of the quartet of nuclei ($^{55}$Ni, $^{57}$Ni, $^{55}$Co and
$^{57}$Co), one neutron away from $^{56}$Ni, the N=Z=28 double magic nucleus.
Using the $^{1}$H($^{56}$Ni,d)$^{55}$Ni transfer reaction in inverse
kinematics, neutron spectroscopic factors, spins and parities have been
extracted for the f$_{7/2}$, p$_{3/2}$ and the s$_{1/2}$ hole-states of
$^{55}$Ni. This new data provides a benchmark for large basis calculations that
include nucleonic orbits in both the sd and pf shells. State of the art
calculations have been performed to describe the excitation energies and
spectroscopic factors of the s$_{1/2}$ hole-state below Fermi energy.


title: Numerical application and Turbo C program using the Gauss-Jordan Method

abstract:
  The article presents the general notions and algorithm about the Gauss-Jordan
method. An eloquent example is given and the Turbo C program illustrated this
method. We conclude that we can obtain by this method the determinant, by
simple calculations and reducing the rounding errors


title:
Transport through side-coupled multilevel double quantum dots in the
  Kondo regime

abstract:
  We analyze the transport properties of a double quantum dot device in the
side-coupled configuration. A small quantum dot (QD), having a single relevant
electronic level, is coupled to source and drain electrodes. A larger QD, whose
multilevel nature is considered, is tunnel-coupled to the small QD. A Fermi
liquid analysis shows that the low temperature conductance of the device is
determined by the total electronic occupation of the double QD. When the small
dot is in the Kondo regime, an even number of electrons in the large dot leads
to a conductance that reaches the unitary limit, while for an odd number of
electrons a two stage Kondo effect is observed and the conductance is strongly
suppressed. The Kondo temperature of the second stage Kondo effect is strongly
affected by the multilevel structure of the large QD. For increasing level
spacing, a crossover from a large Kondo temperature regime to a small Kondo
temperature regime is obtained when the level spacing becomes of the order of
the large Kondo temperature.


title: Metrizable DH-spaces of the first category

abstract:
  We show that if a separable space X has a meager open subset containing a
copy of the Cantor set 2^\omega, then X has $\frak{c}$ types of countable dense
subsets. We suggest a generalization of the \lambda-set for non-separable
spaces. Let X be an h-homogeneous \Lambda-set. Then X is densely homogeneous
and (X \setminus A) is homeomorphic to X for every \sigma-discrete A \subset X.