title: Anomalous Cooper pair interference on Bi2Te3 surface

abstract:
  It is believed that the edges of a chiral p-wave superconductor host Majorana
modes, relating to a mysterious type of fermions predicted seven decades ago.
Much attention has been paid to search for p-wave superconductivity in
solid-state systems, including recently those with strong spin-orbit coupling
(SOC). However, smoking-gun experiments are still awaited. In this work, we
have performed phase-sensitive measurements on particularly designed
superconducting quantum interference devices constructing on the surface of
topological insulators Bi2Te3, in such a way that a substantial portion of the
interference loop is built on the proximity-effect-induced superconducting
surface. Two types of Cooper interference patterns have been recognized at low
temperatures. One is s-wave like and is contributed by a zero-phase loop
inhabited in the bulk of Bi2Te3. The other, being identified to relate to the
surface states, is anomalous for that there is a phase shift between the
positive and negative bias current directions. The results support that the
Cooper pairs on the surface of Bi2Te3 have a 2\pi Berry phase which makes the
superconductivity p_x+ip_y-wave-like. Mesoscopic hybrid rings as constructed in
this experiment are presumably arbitrary-phase loops good for studying
topological quantum phenomena.


title:
Magnetic phase diagrams, domain switching and a quantum phase transition
  of the quasi-1D Ising-like antiferromagnet BaCo2V2O8

abstract:
  In the effective Ising spin-1/2 antiferromagnetic chain system
BaCo$_2$V$_2$O$_8, the magnetic-field influence is highly anisotropic. For
magnetic fields along the easy axis $c$, the N\'{e}el order is strongly
suppressed already for low fields and an incommensurate order is entered above
4 T. We present a detailed study of the magnetic phase diagrams for different
magnetic field directions, which are derived from magnetization data,
high-resolution thermal expansion and magnetostriction measurements as well as
from the thermal conductivity. Zero-field thermal expansion data reveal that
the magnetic transition is accompanied by an orthorhombic distortion within the
$ab$ plane. Under ambient conditions the crystals are heavily twinned, but the
domain orientation can be influenced either by applying uniaxial pressure or a
magnetic field along the [100] direction. In addition, our data reveal a
pronounced in-plane magnetic anisotropy for fields applied within the $ab$
plane. For $H || [110]$, the magnetic field influence on T$_N$ is weak, whereas
for magnetic fields applied along [100], T$_N$ vanishes at about 10 T and the
zero-field N\'{e}el order is completely suppressed as is confirmed by neutron
diffraction data. The second-order phase transition strongly suggests a quantum
critical point being present at $H\simeq 10$ T parallel [100], where the
N\'{e}el order probably changes to a spin-liquid state.


title: On existence of periodic solutions for Kepler type problems

abstract:
  We prove existence and multiplicity of periodic motions for the forced 2-body
problem under conditions of topological character. In the different cases, the
lower bounds obtained for the number of solutions are related to the winding
number of a curve in the plane, the homology of a space in $\R^3$, the knot
type of a curve and the link type of a set of curves. Also, the results are
applied to the restricted $n$-body problem.


title: The smallest nonevasive graph property

abstract:
  A property of n-vertex graphs is called evasive if every algorithm testing
this property by asking questions of the form "is there an edge between
vertices u and v" requires, in the worst case, to ask about all pairs of
vertices. Most "natural" graph properties are either evasive or conjectured to
be such, and of the few examples of nontrivial nonevasive properties scattered
in the literature the smallest one has n=6. We exhibit a nontrivial, nonevasive
property of 5-vertex graphs and show that it is essentially the unique such
with n at most 5.


title:
Will there be again a transition from acceleration to deceleration in
  course of the dark energy evolution of the universe?

abstract:
  In this work we consider the evolution of the interactive dark fluids in the
background of homogeneous and isotropic FRW model of the universe. The dark
fluids consist of a warm dark matter and a dark energy and both are described
as perfect fluid with barotropic equation of state. The dark species interact
non-gravitationally through an additional term in the energy conservation
equations. An autonomous system is formed in the energy density spaces and
fixed points are analyzed. A general expression for the deceleration parameter
has been obtained and it is possible to have more than one zero of the
deceleration parameter. Finally, vanishing of the deceleration parameter has
been examined with some examples.


title: An upper bound theorem for a class of flag weak pseudomanifolds

abstract:
  If K is an odd-dimensional flag closed manifold, flag generalized homology
sphere or a more general flag weak pseudomanifold with sufficiently many
vertices, then the maximal number of edges in K is achieved by the balanced
join of cycles.
  The proof relies on stability results from extremal graph theory. In the case
of manifolds we also offer an alternative (very) short proof utilizing the
non-embeddability theorem of Flores.
  The main theorem can also be interpreted without the topological contents as
a graph-theoretic extremal result about a class of graphs such that 1) every
maximal clique in the graph has size d+1 and 2) every clique of size d belongs
to exactly two maximal cliques.


title: Supermassive galactic centre with repulsive gravity

abstract:
  Repulsive gravity has its origin in the 1939 article of Oppenheimer and
Snyder which describes a collapsar, that is an idealized star of
non-interacting material (dust) collapsing under its own gravity. The stellar
material has a final state resembling a football, that is a significant part of
it is concentrated in a thin surface shell. An interior pressure is exerted by
the strong gravitational field, equivalent to a negative mass. However, the OS
solution has been misunderstood, the shell's position being incorrectly
identified with the "event horizon" in black-hole theory. While half the
material is concentrated in a shell occupying a small fraction of the radius,
some material is spread throughout the interior, unlike the concentration in a
black hole's singularity. We deal with the singularity in density at the shell
surface, by including Fermi pressure of degenerate electrons for a shell
density comparable to a solar mass-sized white dwarf. Because the high-density
region is concentrated in a shell, instead of at the centre as in a black hole,
our conclusion is that repulsive gravity enables the existence of supermassive
white dwarfs.


title: A Metal-Insulator transition induced by Random Dipoles

abstract:
  We study the localization properties of a test dipole feeling the disordered
potential induced by dipolar impurities trapped at random positions in an
optical lattice. This random potential is marked by correlations which are a
convolution of short-range and long-range ones. We show that when short-range
correlations are dominant, extended states can appear in the spectrum.
Introducing long-range correlations, the extended states, if any, are wiped out
and localization is restored over the whole spectrum. Moreover, long-range
correlations can either increase or decrease the localization length at the
center of the band, which indicates a richer behavior than previously
predicted.


title: Is hexagonal InMnO3 ferroelectric?

abstract:
  The presence of ferroelectricity in hexagonal (h-)InMnO3 has been highly
under debate. The results of our comprehensive experiments of low-temperature
(T) polarization, TEM and HAADF-STEM on well-controlled h-InMnO3 reveal that
the ground state is ferroelectric with P6_3cm symmetry, but a non-ferroelectric
P-3c1 state exists at high T, and can be quenched to room T. We also found that
the ferroelectric P6_3cm state of h-InMnO3 exhibits the domain configuration of
topological vortices, as has been observed in h-REMnO3 (RE=rare earths).


title: 3He: Does the problem persists?

abstract:
  To understand the chemical evolution of the Galaxy, we need to understand the
contribution of PNe in the 3He abundance. 3He abundances have been detected
only in a couple of PNe, their abundances are consistent with the standard
models, in which 3He is produced in significant quantities by stars of
1-2M_sun. However, for all the other PNe observed to date there have been no
detections, therefore only upper limits in their abundance can be calculated.
Observations of the 3He+ emission line using the VLA towards the PNe IC 418,
NGC 6572 and NGC 7009 were used to obtain upper limits for their 3He abundance.
Because the abundance of 3He in HII regions, the ISM and the proto-solar system
is much lower than what is predicted, new chemical models were proposed. The
resulting evolution of 3He, based on stellar evolution models, can be
consistent with the values determined in pre-solar material and the ISM if 96
percent of the population of stars with mass below 2.5M_sun has undergone
enhanced 3He depletion. This implies that unless the combined sample of PNe
that has been observed so far is very atypical, the solution to the "The 3He
Problem" lies elsewhere. However, the results presented here suggest that more
observations are needed in order to make a strong conclusion about the stellar
evolution models.


title: Non-relativistic limits of Maxwell's equations

abstract:
  In 1973, Le Bellac and Levy-Leblond (Nuovo Cimento B 14, 217-234) discovered
that Maxwell's equations possess two non-relativistic Galilei-covariant limits,
corresponding to E >> cB (electric limit) or E << cB (magnetic limit). Here, we
provide a systematic, yet simple, derivation of these two limits based on a
dimensionless form of Maxwell's equations and an expansion of the electric and
magnetic fields in a power series of some small parameters. Using this
procedure, all previously known results are recovered in a natural and
unambiguous way. Some further extensions are also proposed.


title: Embeddings of Line-grassmannians of Polar Spaces in Grassmann Varieties

abstract:
  An embedding of a point-line geometry \Gamma is usually defined as an
injective mapping \epsilon from the point-set of \Gamma to the set of points of
a projective space such that \epsilon(l) is a projective line for every line l
of \Gamma, but different situations have lately been considered in the
literature, where \epsilon(l) is allowed to be a subline of a projective line
or a curve. In this paper we propose a more general definition of embedding
which includes all the above situations and we focus on a class of embeddings,
which we call Grassmman embeddings, where the points of \Gamma are firstly
associated to lines of a projective geometry PG(V), next they are mapped onto
points of PG(V\wedge V) via the usual projective embedding of the
line-grassmannian of PG(V) in PG(V\wedge V). In the central part of our paper
we study sets of points of PG(V\wedge V) corresponding to lines of PG(V)
totally singular for a given pseudoquadratic form of V. Finally, we apply the
results obtained in that part to the investigation of Grassmann embeddings of
several generalized quadrangles.


title: Orbital periods and Accretion disc structure of four AM CVn systems

abstract:
  Phase-resolved spectroscopy of four AM CVn systems obtained with the William
Herschel Telescope and the Gran Telescopio de Canarias (GTC) is presented.
SDSS\,J120841.96+355025.2 was found to have an orbital period of
52.96$\pm$0.40\,min and shows the presence of a second bright spot in the
accretion disc. The average spectrum contains strong Mg\,{\sc i} and Si\,{\sc
i/ii} absorption lines most likely originating in the atmosphere of the
accreting white dwarf. SDSS\,J012940.05+384210.4 has an orbital period of
37.555$\pm$0.003 min. The average spectrum shows the Stark broadened absorption
lines of the DB white dwarf accretor. The orbital period is close to the
previously reported superhump period of 37.9\,min. Combined, this results in a
period excess $\epsilon$=0.0092$\pm$0.0054 and a mass ratio $q=0.031\pm$0.018.
SDSS\,J164228.06+193410.0 displays an orbital period of 54.20$\pm$1.60\,min
with an alias at 56.35\,min. The average spectrum also shows strong Mg\,{\sc i}
absorption lines, similar to SDSS\,J120841.96+355025.2.
SDSS\,J152509.57+360054.50 displays an period of 44.32$\pm$0.18\,min. The
overall shape of the average spectrum is more indicative of shorter period
systems in the 20-35 minute range. The accretor is still clearly visible in the
pressure broadened absorption lines most likely indicating a hot donor star
and/or a high mass accretor. Flux ratios for several helium lines were
extracted from the Doppler tomograms for the disc and bright spot region, and
compared with single-slab LTE models with variable electron densities and path
lengths to estimate the disc and bright spot temperature. A good agreement
between data and the model in three out of four systems was found for the disc
region. All three systems show similar disc temperatures of $\sim$10\,500 K. In
contrast, only weak agreement between observation and models was found for the
bright spot region.


title: Spherical varieties with the $A_k$-property

abstract:
  An algebraic variety is said to have the $A_k$-property if any $k$ points are
contained in some common affine open neighbourhood. A theorem of W{\l}odarczyk
states that a normal variety has the $A_2$-property if and only if it admits a
closed embedding into a toric variety. Spherical varieties can be regarded as a
generalization of toric varieties, but they do not have the $A_2$-property in
general. We provide a combinatorial criterion for the $A_k$-property of
spherical varieties by combining the theory of bunched rings with the Luna-Vust
theory of spherical embeddings.


title: A Gravitational Entropy Proposal

abstract:
  We propose a thermodynamically motivated measure of gravitational entropy
based on the Bel-Robinson tensor, which has a natural interpretation as the
effective super-energy-momentum tensor of free gravitational fields. The
specific form of this measure differs depending on whether the gravitational
field is Coulomb-like or wave-like, and reduces to the Bekenstein-Hawking value
when integrated over the interior of a Schwarzschild black hole. For scalar
perturbations of a Robertson-Walker geometry we find that the entropy goes like
the Hubble weighted anisotropy of the gravitational field, and therefore
increases as structure formation occurs. This is in keeping with our
expectations for the behaviour of gravitational entropy in cosmology, and
provides a thermodynamically motivated arrow of time for cosmological solutions
of Einstein's field equations. It is also in keeping with Penrose's Weyl
curvature hypothesis.


title: Network Detection Theory and Performance

abstract:
  Network detection is an important capability in many areas of applied
research in which data can be represented as a graph of entities and
relationships. Oftentimes the object of interest is a relatively small subgraph
in an enormous, potentially uninteresting background. This aspect characterizes
network detection as a "big data" problem. Graph partitioning and network
discovery have been major research areas over the last ten years, driven by
interest in internet search, cyber security, social networks, and criminal or
terrorist activities. The specific problem of network discovery is addressed as
a special case of graph partitioning in which membership in a small subgraph of
interest must be determined. Algebraic graph theory is used as the basis to
analyze and compare different network detection methods. A new Bayesian network
detection framework is introduced that partitions the graph based on prior
information and direct observations. The new approach, called space-time threat
propagation, is proved to maximize the probability of detection and is
therefore optimum in the Neyman-Pearson sense. This optimality criterion is
compared to spectral community detection approaches which divide the global
graph into subsets or communities with optimal connectivity properties. We also
explore a new generative stochastic model for covert networks and analyze using
receiver operating characteristics the detection performance of both classes of
optimal detection techniques.

categories: cs.SI cs.LG math.ST physics.soc-ph stat.ML stat.TH


title: Intervention-Based Stochastic Disease Eradication

abstract:
  Disease control is of paramount importance in public health with infectious
disease extinction as the ultimate goal. Although diseases may go extinct due
to random loss of effective contacts where the infection is transmitted to new
susceptible individuals, the time to extinction in the absence of control may
be prohibitively long. Thus intervention controls, such as vaccination of
susceptible individuals and/or treatment of infectives, are typically based on
a deterministic schedule, such as periodically vaccinating susceptible children
based on school calendars. In reality, however, such policies are administered
as a random process, while still possessing a mean period. Here, we consider
the effect of randomly distributed intervention as disease control on large
finite populations. We show explicitly how intervention control, based on mean
period and treatment fraction, modulates the average extinction times as a
function of population size and rate of infection spread. In particular, our
results show an exponential improvement in extinction times even though the
controls are implemented using a random Poisson distribution. Finally, we
discover those parameter regimes where random treatment yields an exponential
improvement in extinction times over the application of strictly periodic
intervention. The implication of our results is discussed in light of the
availability of limited resources for control.


title:
Fast closed-loop optimal control of ultracold atoms in an optical
  lattice

abstract:
  We present experimental evidence of the successful closed-loop optimization
of the dynamics of cold atoms in an optical lattice. We optimize the loading of
an ultracold atomic gas minimizing the excitations in an array of
one-dimensional tubes (3D-1D crossover) and we perform an optimal crossing of
the quantum phase-transition from a Superfluid to a Mott-Insulator in a
three-dimensional lattice. In both cases we enhance the experiment performances
with respect to those obtained via adiabatic dynamics, effectively speeding up
the process by more than a factor three while improving the quality of the
desired transformation.


title:
Sequential sampling models in computational psychiatry: Bayesian
  parameter estimation, model selection and classification

abstract:
  Current psychiatric research is in crisis. In this review I will describe the
causes of this crisis and highlight recent efforts to overcome current
challenges. One particularly promising approach is the emerging field of
computational psychiatry. By using methods and insights from computational
cognitive neuroscience, computational psychiatry might enable us to move from a
symptom-based description of mental illness to descriptors based on objective
computational multidimensional functional variables. To exemplify this I will
survey recent efforts towards this goal. I will then describe a set of methods
that together form a toolbox of cognitive models to aid this research program.
At the core of this toolbox are sequential sampling models which have been used
to explain diverse cognitive neuroscience phenomena but have so far seen little
adoption in psychiatric research. I will then describe how these models can be
fitted to subject data and highlight how hierarchical Bayesian estimation
provides a rich framework with many desirable properties and benefits compared
to traditional optimization-based approaches. Finally, non-parametric Bayesian
methods provide general solutions to the problem of classifying mental illness
within this framework.


title: On the asymptotic density of the support of a Dirichlet convolution

abstract:
  Let v be a multiplicative arithmetic function with support of positive
asymptotic density. We prove that for any not identically zero arithmetic
function f such that \sum_{f(n) \neq 0} 1 / n < \infty, the support of the
Dirichlet convolution f * v possesses a positive asymptotic density. When f is
a multiplicative function, we give also a quantitative version of this claim.
This generalizes a previous result of P. Pollack and the author, concerning the
support of M\"obius and Dirichlet transforms of arithmetic functions.


title: Eigenvalue estimates for submanifolds of warped product spaces

abstract:
  We give lower bounds for the fundamental tone of open sets in minimal
submanifolds immersed into warped product spaces of type $N^n \times_f Q^q$,
where $f \in C^\infty(N)$. We also study the essential spectrum of these
minimal submanifolds.


title:
An educational path for the magnetic vector potential and its physical
  implications

abstract:
  We present an educational path on the magnetic vector potential A addressed
to undergraduate students and to pre-service physics teachers. Starting from
the generalized Ampere-Laplace law, in the framework of a slowly varying
time-dependent field approximation, the magnetic vector potential is written in
terms of its empirical referent, i. e. the conduction current. Therefore, once
the currents are known, our approach allows a clear and univocal physical
determination of A overcoming the mathematical indeterminacy due to the gauge
transformations. We have no need to fix a gauge, since for slowly varying
time-dependent electric and magnetic fields, the natural gauge for A is the
Coulomb one. We stress the difference between our approach and those usually
presented in the literature. Finally, a physical interpretation of the magnetic
vector potential is discussed and some examples of calculation of A are
analysed.


title: Magnetic and Magnetocaloric Exploration of Fe rich (Mn,Fe)2(P,Ge)

abstract:
  We explored the Fe rich side of the (Mn,Fe)2(P,Ge) magnetocaloric system. The
transition temperature of this system is extremely easy to tune with careful
manipulation of Fe and Ge content as well as stoichiometrical proportions,
which gives rise to the real possibility of lowering the price of this compound
and thus make it economically viable for practical magnetocaloric applications.
Novel and unexpected magnetic properties observed in this system suggest an
exciting potential for permanent magnet application in a limited concentration
range.


title:
A new prediction of wavelength selection in radial viscous fingering
  involving normal and tangential stresses

abstract:
  We reconsider the radial Saffman-Taylor instability, when a fluid injected
from a point source displaces another fluid with a higher viscosity in a
Hele-Shaw cell, where the fluids are confined between two neighboring flat
plates. The advancing fluid front is unstable and forms fingers along the
circumference. The so-called Brinkman equations is used to describe the flow
field, which also takes into account viscous stresses in the plane and not only
viscous stresses due to the confining plates like the Darcy equation. The
dispersion relation agrees better with the experimental results than the
classical linear stability analysis of radial fingering in Hele-Shaw cells that
uses Darcy's law as a model for the fluid motion.


title:
On the approximate shape of degree sequences that are not potentially
  $H$-graphic

abstract:
  A sequence of nonnegative integers $\pi$ is {\it graphic} if it is the degree
sequence of some graph $G$. In this case we say that $G$ is a
\textit{realization} of $\pi$, and we write $\pi=\pi(G)$. A graphic sequence
$\pi$ is {\it potentially $H$-graphic} if there is a realization of $\pi$ that
contains $H$ as a subgraph.
  Given nonincreasing graphic sequences $\pi_1=(d_1,\ldots,d_n)$ and $\pi_2 =
(s_1,\ldots,s_n)$, we say that $\pi_1$ {\it majorizes} $\pi_2$ if $d_i \geq
s_i$ for all $i$, $1 \leq i \leq n$. In 1970, Erd\H{o}s showed that for any
$K_{r+1}$-free graph $H$, there exists an $r$-partite graph $G$ such that
$\pi(G)$ majorizes $\pi(H)$. In 2005, Pikhurko and Taraz generalized this
notion and showed that for any graph $F$ with chromatic number $r+1$, the
degree sequence of an $F$-free graph is, in an appropriate sense, nearly
majorized by the degree sequence of an $r$-partite graph.
  In this paper, we give similar results for degree sequences that are not
potentially $H$-graphic. In particular, there is a graphic sequence $\pi^*(H)$
such that if $\pi$ is a graphic sequence that is not potentially $H$-graphic,
then $\pi$ is close to being majorized by $\pi^*(H)$. Similar to the role
played by complete multipartite graphs in the traditional extremal setting, the
sequence $\pi^*(H)$ asymptotically gives the maximum possible sum of a graphic
sequence $\pi$ that is not potentially $H$-graphic.


title:
The signature of the Warm Hot Intergalactic Medium in WMAP and the
  forthcoming PLANCK data

abstract:
  We compute the cross-correlation between the Warm-Hot Intergalactic Medium
and maps of Cosmic Microwave Background temperature anisotropies using a
log-normal probability density function to describe the weakly non-linear
matter density field. We search for this contribution in the data measured by
the Wilkinson Microwave Anisotropy Probe. We use a template of projected matter
density reconstructed from the Two-Micron All-Sky Redshift Survey as a tracer
of the electron distribution. The spatial distribution of filaments is modeled
using the recently developed Augmented Lagrangian Perturbation Theory. On the
scales considered here, the reconstructed density field is very well described
by the assumed log-normal distribution function. We predict that the
cross-correlation will have an amplitude of $0.03-0.3\mu$K. The measured value
is close to $1.5\mu$K, compatible with random alignments between structure in
the template and in the temperature anisotropy data. Using the W1 Differencing
Assembly to remove this systematic gives a residual correlation dominated by
Galactic foregrounds. Planck could detect the Warm-Hot Medium if it is well
traced by the density field reconstructed from galaxy surveys. The 217GHz
channel will allow to eliminate spurious contributions and its large frequency
coverage can show the sign change from the Rayleigh-Jeans to the Wien part of
the spectrum, characteristic of the thermal Sunyaev-Zeldovich effect.


title:
Non-uniqueness phase of Bernoulli percolation on reflection groups for
  some polyhedra in H^3

abstract:
  In the present paper I consider Cayley graphs of reflection groups of
finite-sided Coxeter polyhedra in 3-dimensional hyperbolic space H^3, with
standard sets of generators. As the main result, I prove the existence of
non-trivial non-uniqueness phase of bond and site Bernoulli percolation on such
graphs, i.e. that p_c < p_u, for two classes of such polyhedra:
  * for any k-hedra as above with k at least 13;
  * for any compact right-angled polyhedra as above.
  I also establish a natural lower bound for the growth rate of such Cayley
graphs (when the number of faces of the polyhedron is at least 6; see thm. 5.2)
and an upper bound for the growth rate of the sequence (#{simple cycles of
length n through o})_n for a regular graph of degree at least 2 with a
distinguished vertex o, depending on its spectral radius (see thm. 5.1 and rem.
2.3), both used to prove the main result.


title:
The role of the ligand layer for photoluminescence spectral diffusion of
  CdSe/ZnS nanoparticles

abstract:
  The time-resolved photoluminescence (PL) characteristics of single CdSe/ZnS
nanoparticles, embedded in a PMMA layer is studied at room temperature. We
observe a strong spectral jitter of up to 55 meV, which is correlated with a
change in the observed linewidth. We evaluate this correlation effect using a
simple model, based on the quantum confined Stark effect induced by a diffusing
charge in the vicinity of the nanoparticle. This allows us to derive a mean
distance between the center of the particle and the diffusing charge of
approximately 3.3 nm on average, as well as a mean charge carrier displacement
within the integration time. The distances are larger than the combined radius
of particle core and shell of about 3 nm, but smaller than the overall radius
of 5 nm including ligands. These results are reproducible, even for particles
which exhibit strong blueing, with shifts of up to 150 meV. Both the statistics
and its independence of core-shell alterations lead us to conclude that the
charge causing the spectral jitter is situated in the ligands.


title: Twins in graphs

abstract:
  A basic pigeonhole principle insures an existence of two objects of the same
type if the number of objects is larger than the number of types. Can such a
principle be extended to a more complex combinatorial structure? Here, we
address such a question for graphs. We call two disjoint subsets $A, B$ of
vertices \emph{\textbf{twins}} if they have the same cardinality and induce
subgraphs of the same size.
  Let $t(G)$ be the largest $k$ such that $G$ has twins on $k$ vertices each.
We provide the bounds on $t(G)$ in terms of the number of edges and vertices
using discrepancy results for induced subgraphs. In addition, we give
conditions under which $t(G)= |V(G)|/2$ and show that if $G$ is a forest then
$t(G) \geq |V(G)|/2 - 1$.


title: Probing reionization with LOFAR using 21-cm redshift space distortions

abstract:
  One of the most promising ways to study the epoch of reionization (EoR) is
through radio observations of the redshifted 21-cm line emission from neutral
hydrogen. These observations are complicated by the fact that the mapping of
redshifts to line-of-sight positions is distorted by the peculiar velocities of
the gas. Such distortions can be a source of error if they are not properly
understood, but they also encode information about cosmology and astrophysics.
We study the effects of redshift space distortions on the power spectrum of
21-cm radiation from the EoR using large scale $N$-body and radiative transfer
simulations. We quantify the anisotropy introduced in the 21-cm power spectrum
by redshift space distortions and show how it evolves as reionization
progresses and how it relates to the underlying physics. We go on to study the
effects of redshift space distortions on LOFAR observations, taking instrument
noise and foreground subtraction into account. We find that LOFAR should be
able to directly observe the power spectrum anisotropy due to redshift space
distortions at spatial scales around $k \sim 0.1$ Mpc$^{-1}$ after $\gtrsim$
1000 hours of integration time. At larger scales, sample errors become a
limiting factor, while at smaller scales detector noise and foregrounds make
the extraction of the signal problematic. Finally, we show how the
astrophysical information contained in the evolution of the anisotropy of the
21-cm power spectrum can be extracted from LOFAR observations, and how it can
be used to distinguish between different reionization scenarios.


title:
Thermal balance and quantum heat transport in nanostructures thermalized
  by local Langevin heat baths

abstract:
  Modeling of thermal transport in practical nanostructures requires making
trade-offs between the size of the system and the completeness of the model. We
study quantum heat transfer in a self-consistent thermal bath setup consisting
of two lead regions connected by a center region. Atoms both in the leads and
in the center region are coupled to quantum Langevin heat baths that mimic the
damping and dephasing of phonon waves by anharmonic scattering. This approach
treats the leads and the center region on same footing and thereby allows for a
simple and physically transparent thermalization of the system, enabling also
perfect acoustic matching between the leads and the center region. Increasing
the strength of the coupling reduces the mean free path of phonons and
gradually shifts phonon transport from ballistic regime to diffusive regime. In
the center region, the bath temperatures are determined self-consistently from
the requirement of zero net energy exchange between the local heat bath and
each atom. By solving the stochastic equations of motion in frequency space and
averaging over noise using the general fluctuation-dissipation relation derived
by Dhar and Roy [J. Stat. Phys. 125, 801 (2006)], we derive the formula for
thermal current, which contains the Caroli formula for phonon transmission
function and reduces to the Landauer-B\"uttiker formula in the limit of
vanishing coupling to local heat baths.


title:
Nonlocal imaging by conditional averaging of random reference
  measurements

abstract:
  We report the nonlocal imaging of an object by conditional averaging of the
random exposure frames of a reference detector, which only sees the freely
propagating field from a thermal light source. A bucket detector, synchronized
with the reference detector, records the intensity fluctuations of an identical
beam passing through the object mask. These fluctuations are sorted according
to their values relative to the mean, then the reference data in the
corresponding time-bins for a given fluctuation range are averaged, to produce
either positive or negative images. Since no correlation calculations are
involved, this correspondence imaging technique challenges our former
interpretations of "ghost" imaging. Compared with conventional correlation
imaging or compressed sensing schemes, both the number of exposures and
computation time are greatly reduced, while the visibility is much improved. A
simple statistical model is presented to explain the phenomenon.


title: The Coronal Abundances of Mid-F Dwarfs

abstract:
  A Chandra spectrum of the moderately active nearby F6 V star Pi3 Ori is used
to study the coronal properties of mid-F dwarfs. We find that Pi3 Ori's coronal
emission measure distribution is very similar to those of moderately active G
and K dwarfs, with an emission measure peak near $\log T=6.6$ seeming to be
ubiquitous for such stars. In contrast to coronal temperature, coronal
abundances are known to depend on spectral type for main sequence stars. Based
on this previously known relation, we expected Pi3 Ori's corona to exhibit an
extremely strong "FIP effect," a phenomenon first identified on the Sun where
elements with low "First Ionization Potential" (FIP) are enhanced in the
corona. We instead find that Pi3 Ori's corona exhibits a FIP effect essentially
identical to that of the Sun and other early G dwarfs, perhaps indicating that
the increase in FIP bias towards earlier spectral types stops or at least slows
for F stars. We find that Pi3 Ori's coronal characteristics are significantly
different from two previously studied mid-F stars, Procyon (F5 IV-V) and Tau
Boo (F7 V). We believe Pi3 Ori is more representative of the coronal
characteristics of mid-F dwarfs, with Procyon being different because of
luminosity class, and Tau Boo being different because of the effects of one of
two close companions, one stellar (Tau Boo B: M2 V) and one planetary.


title:
Th\'eorie de la mesure dans les lieux r\'eguliers. ou : Les
  intersections cach\'ees dans le paradoxe de Banach-Tarski

abstract:
  It is well known that axiom of choice implies the existence of non-measurable
sets for Lebesgue's measure on R as well as the existence of "paradoxical"
decompositions of the unit ball of R^3 (Banach-Tarski). This is generally
interpreted as the price to be paid for the numerous services provided by this
axiom. The theory proposed by Olivier Leroy shows that we can have
simultaneously axiom of choice and " everything is measurable " it takes place
within the framework of "locales" which are particular cases of Grothendieck's
toposes : a "locale" is just a poset which has the formal properties of the
poset of open subsets of a topological space. "Locales" have already been the
object of numerous studies (cf for example "Sheaves in Geometry and Logic" of
S.Mac Lane and I.Moerdijk. Springer 92.). One of the remarkable aspects of this
theory is that it applies in a relevant way to the usual topological spaces in
which it shows up " non standard sub-spaces " (sub-locales)); with for
consequence that the intersection (in the meaning of locale) of ordinary
sub-spaces is not anymore necessarily a (ordinary) sub-space. We have for
example a sub-locale of R (called generic sub-locale of R) which is the
intersection of dense open sets and which is still dense (although pointless).
The most striking result is doubtless that the natural continuation of the
measure of Lebesgue (on [0,1] for example) on the open sets to the totality of
sub-locales of [0,1] is a sigma additive outside regular measure The
"paradoxical " partitions which gave non-measurable subsets in the classical
context are no more partitions in the context of locales. There are hidden
intersections.... Jean-Malgoire et Christine Voisin


title:
A new extensive library of PHOENIX stellar atmospheres and synthetic
  spectra

abstract:
  We present a new library of high-resolution synthetic spectra based on the
stellar atmosphere code PHOENIX that can be used for a wide range of
applications of spectral analysis and stellar parameter synthesis. The
spherical mode of PHOENIX was used to create model atmospheres and to derive
detailed synthetic stellar spectra from them. We present a new self-consistent
way of describing micro-turbulence for our model atmospheres. The synthetic
spectra cover the wavelength range from 500AA to 50.000AA with resolutions of
R=500.000 in the optical and near IR, R=100.000 in the IR and a step size of
0.1AA in the UV. The parameter space covers 2.300K<=Teff<=12.000K,
0.0<=log(g)<=+6.0, -4.0<=[Fe/H]<=+1.0, and -0.2<=[alpha/Fe]<=+1.2. The library
is a work in progress and we expect to extend it up to Teff=25.000 K.


title: Red Queen Coevolution on Fitness Landscapes

abstract:
  Species do not merely evolve, they also coevolve with other organisms.
Coevolution is a major force driving interacting species to continuously evolve
ex- ploring their fitness landscapes. Coevolution involves the coupling of
species fit- ness landscapes, linking species genetic changes with their
inter-specific ecological interactions. Here we first introduce the Red Queen
hypothesis of evolution com- menting on some theoretical aspects and empirical
evidences. As an introduction to the fitness landscape concept, we review key
issues on evolution on simple and rugged fitness landscapes. Then we present
key modeling examples of coevolution on different fitness landscapes at
different scales, from RNA viruses to complex ecosystems and macroevolution.


title: Observed Spacetime Dimensionality from Fundamental Principles

abstract:
  It is shown by very simple arguments that the observed 3+1 dimensionality of
spacetime may be understood on the basis of four fundamental principles of
physics namely, Causality, General Covariance, Gauge Invariance and
Renormalizability. This approach not therefore only fixes the spacetime
dimensionality at 3+1, but also imposes the compactification of extra
dimensions in higher dimensional theories based on these principles such as
string theory as an internal consistency requirement rather than an external
imposition.


title: Trees in Wavelet analysis on Vilenkin groups

abstract:
  We consider a class of $(1,M)$-elementary step functions on the $p$-adic
Vilenkin group.
  We prove that $(1,M)$-elementary step function generates a MRA on $p$-adic
Vilenkin group iff it is generated by a rooted tree on the set of vertices
$\{0,1,\dots p-1\}$ with 0 as a root. Bibliography: 14 titles.


title: Codes and caps from orthogonal Grassmannians

abstract:
  In this paper we investigate linear error correcting codes and projective
caps related to the Grassmann embedding $\varepsilon_k^{gr}$ of an orthogonal
Grassmannian $\Delta_k$. In particular, we determine some of the parameters of
the codes arising from the projective system determined by
$\varepsilon_k^{gr}(\Delta_k)$. We also study special sets of points of
$\Delta_k$ which are met by any line of $\Delta_k$ in at most 2 points and we
show that their image under the Grassmann embedding $\varepsilon_k^{gr}$ is a
projective cap.


title:
Momentum distribution for a one-dimensional trapped gas of hard-core
  bosons

abstract:
  Using the exact $N$-particle ground state wave function for a one-dimensional
gas of hard-core bosons in a harmonic trap we develop an algorithm to compute
the reduced single-particle density matrix and corresponding momentum
distribution. Accurate numerical results are presented for up to N=8 particles,
and the momentum distributions are compared to a recent analytic approximation.


title: Analytic functors between presheaf categories over groupoids

abstract:
  The paper studies analytic functors between presheaf categories. Generalising
results of A. Joyal and of R. Hasegawa for analytic endofunctors on the
category of sets, we give two characterisations of analytic functors between
presheaf categories over groupoids: (i) as functors preserving filtered
colimits, quasi-pullbacks, and cofiltered limits; and (ii) as functors
preserving filtered colimits and wide quasi-pullbacks. The development
establishes that small groupoids, analytic functors between their presheaf
categories, and quasi-cartesian natural transformations between them form a
2-category.


title: Anomalous Effects in a Trapped Bose-Einstein Condensate

abstract:
  We study the anomalous density in an ultra-cold trapped bose gas in a
variational framework, for both zero and finite temperature. We show that it is
finite in 1D, while it is logarithmically and linearly divergent in 2D and 3D.
The renormalization that we adopt is more reliable and compatible with the
variational scheme. The main outcome is that the anomalous and non condensate
densities are of the


title: Tunable polaronic conduction in anatase TiO2

abstract:
  Oxygen vacancies created in anatase TiO2 by UV photons (80 - 130 eV) provide
an effective electron-doping mechanism and induce a hitherto unobserved
dispersive metallic state. Angle resolved photoemission (ARPES) reveals that
the quasiparticles are large polarons. These results indicate that anatase can
be tuned from an insulator to a polaron gas to a weakly correlated metal as a
function of doping and clarify the nature of conductivity in this material.


title:
Gravitationally Driven Electromagnetic Perturbations of Neutron Stars
  and Black Holes

abstract:
  Gravitational perturbations of neutron stars and black holes are well known
sources of gravitational radiation. If the compact object is immersed in or
endowed with a magnetic field, the gravitational perturbations would couple to
electromagnetic perturbations and potentially trigger synergistic
electromagnetic signatures. We present a detailed analytic calculation of the
dynamics of coupled gravitational and electromagnetic perturbations for both
neutron stars and black holes. We discuss the prospects for detecting the
electromagnetic waves in these scenarios and the potential that these waves
have for providing information about their source.


title:
The Magnetic Structure of Individual Flux Vortices in Superconducting
  MgB2 Derived using Transmission Electron Microscopy

abstract:
  Images of flux vortices in superconductors acquired by transmission electron
microscopy should allow a quantitative determination of their magnetic
structure but so far, only visual comparisons have been made between
experimental images and simulations. Here, we make a quantitative comparison
between Fresnel images and simulations based on the modified London equation to
investigate the magnetic structure of flux vortices in MgB2. This technique
gives an absolute, low-field (~30 Oe) measurement of the penetration depth from
images of single vortices. We found that these simulations gave a good fit to
the experimental images and that if all the other parameters in the fit were
known, the penetration depth for individual vortices could be measured with an
accuracy of +/- 5 nm. Averaging over 17 vortices gave a penetration depth in
the ab plane of 113 +/- 2 at 10.8 K assuming that the entire thickness of the
sample was superconducting. The main uncertainty in this measurement was the
proportion of the specimen which was superconducting. Allowing for a
non-superconducting layer of up to 50 nm thickness on the specimen surfaces
gave a penetration depth in the range 100-115 nm, close to values of 90 +/- 2
nm obtained by small-angle neutron scattering and 118-138 nm obtained by
radio-frequency measurements. We also discuss the use of the transport of
intensity equation which should, in principle, give a model-independent measure
of the magnetic structure of flux vortices.


title:
Direct time domain sampling of sub-THz coherent acoustic phonon spectra
  in SrTiO$_3$ using ultrafast X-ray diffraction

abstract:
  We synthesize sub-THz longitudinal quasi-monochromatic acoustic phonons in a
SrTiO$_3$ single crystal using a SrRuO$_3$/SrTiO$_3$ superlattice as an
optical-acoustic transducer. The generated acoustic phonon spectrum is
determined using ultrafast X-ray diffraction. The analysis of the generated
phonon spectrum in the time domain reveals a k-vector dependent phonon
lifetime. It is observed that even at sub-THz frequencies the phonon lifetime
agrees with the 1/$\omega^2$ power law known from Akhiezer's model for hyper
sound attenuation. The observed shift of the synthesized spectrum to the higher
$q$ is discussed in the framework of non-linear effects appearing due to the
high amplitude of the synthesized phonons.


title:
Effective description of tunneling in a time-dependent potential with
  applications to voltage switching in Josephson junctions

abstract:
  We propose to use a time-dependent imaginary potential to describe quantum
mechanical tunneling through time-varying potential barriers. We use Gamow
solutions for stationary tunneling problems to justify our choice of potential,
and we apply our method to describe tunneling of a mesoscopic quantum variable:
the phase change across a Josephson junction. The Josephson junction phase
variable behaves as the position coordinate of a particle moving in a tilted
washboard potential, and our general solution to the motion in such a potential
with a time-dependent tilt reproduces a number of features associated with
voltage switching in Josephson junctions. Apart from applications as artificial
atoms in quantum information studies, the Josephson junction may serve as an
electric field sensitive detector, and our studies provide a detailed
understanding of how the voltage switching dynamics couples to the electric
field amplitude.


title: Relational Quadrilateralland. II. The Quantum Theory

abstract:
  This paper provides the quantum treatment of the relational quadrilateral.
The underlying reduced configuration spaces are $\mathbb{CP}^2$ and the cone
over this, C($\mathbb{CP}^2$). We consider exact free and isotropic HO
potential cases and perturbations about these. Moreover, our purely relational
kinematical quantization is distinct from the usual one for $\mathbb{CP}^2$,
which turns out to carry absolutist connotations instead. Thus this paper is
the first to note absolute-versus-relational motion distinctions at the
kinematical rather than dynamical level, and also an example of value to the
discussion of kinematical quantization along the lines of Isham 1984. This
treatment of the relational quadrilateral is the first relational QM with very
new mathematics for a finite QM model, and is far more typical of the general
quantum relational $N$-a-gon than the previously-studied case of the relational
triangle. We consider useful integrals as regards perturbation theory and the
peaking interpretation of quantum cosmology. We subsequently consider problem
of time applications of this: quantum Kucha\v{r} beables, the Machian version
of the semiclassical approach and the timeless naive Schrodinger
interpretation. These go toward extending the combined Machian
semiclassical-histories-timeless approach of [1] to the case of the
quadrilateral, which will be treated in subsequent papers.


title:
Study the Forward-Backward Asymmetry of the Top Quark Production in the
  Randall-Sundrum Model with an Extension of Strong Interaction

abstract:
  The large forward-backward asymmetry of the top quark pair production
measured by the hadron colliders shed light on new physics signals beyond the
Standard Model. In the Randall-Sundrum model with an additional SU(3) group in
the strong sector, we compare the total cross section and forward-backward
asymmetry of the top quark pair production with the newest data obtained by the
CDF and the D0 collaborations. Our numerical analysis shows that the parameter
$c_q \gtrsim 0.5$, $c_t \sim -0.6\sim-0.8$, $\tan\phi \gtrsim 20$ or $\tan\phi
\leq 1/20$ and the first excitation of axial gluon with a mass about $5
\thicksim 6 \mathrm{TeV}$ can accommodate this large anomaly without violating
other experimental constraints.


title:
Sharp Variable Selection of a Sparse Submatrix in a High-Dimensional
  Noisy Matrix

abstract:
  We observe a $N\times M$ matrix of independent, identically distributed
Gaussian random variables which are centered except for elements of some
submatrix of size $n\times m$ where the mean is larger than some $a>0$. The
submatrix is sparse in the sense that $n/N$ and $m/M$ tend to 0, whereas $n,\,
m, \, N$ and $M$ tend to infinity.
  We consider the problem of selecting the random variables with significantly
large mean values. We give sufficient conditions on $a$ as a function of $n,\,
m,\,N$ and $M$ and construct a uniformly consistent procedure in order to do
sharp variable selection. We also prove the minimax lower bounds under
necessary conditions which are complementary to the previous conditions. The
critical values $a^*$ separating the necessary and sufficient conditions are
sharp (we show exact constants).
  We note a gap between the critical values $a^*$ for selection of variables
and that of detecting that such a submatrix exists given by Butucea and Ingster
(2012). When $a^*$ is in this gap, consistent detection is possible but no
consistent selector of the corresponding variables can be found.


title:
Improving Li$_2$O$_2$ conductance via polaron preemption: an \textit{ab
  initio} study of Si doping

abstract:
  We report on \textit{ab initio} electronic structure simulations of
Li$_2$O$_2$, where 1.6% of lithium atoms are substituted by silicon. It is
demonstrated that this leads to the formation of conducting impurity states in
the band gap of Li$_2$O$_2$. We show that these states originate from the
antibonding orbitals of the oxygen pairs and are remarkably stable against
possible polaron formation (upon electron injection). Through this polaron
preemption mechanism, the proposed compound is expected to show significantly
higher electronic mobility than stoichiometric Li$_2$O$_2$, which could have
significant applications in lithium-air batteries.


title:
Analysis of spin-orbit alignment in the WASP-32, WASP-38, and
  HAT-P-27/WASP-40 systems

abstract:
  We present measurements of the spin-orbit alignment angle, lambda, for the
hot Jupiter systems WASP-32, WASP-38, and HAT-P-27/WASP-40, based on data
obtained using the HARPS spectrograph. We analyse the Rossiter-McLaughlin
effect for all three systems, and also carry out Doppler tomography for WASP-32
and WASP-38. We find that WASP-32 (T_eff = 6140 +90 -100 K) is aligned, with an
alignment angle of lambda = 10.5 +6.4 -6.5 degrees obtained through tomography,
and that WASP-38 (T_eff = 6180 +40 -60 K) is also aligned, with tomographic
analysis yielding lambda = 7.5 +4.7 -6.1 degrees. This latter result provides
an order of magnitude improvement in the uncertainty in lambda compared to the
previous analysis of Simpson et al. (2011). We are only able to loosely
constrain the angle for HAT-P-27/WASP-40 (T_eff = 5190 +160 -170 K) to lambda =
24.2 +76.0 -44.5 degrees, owing to the poor signal-to-noise of our data. We
consider this result a non-detection under a slightly updated version of the
alignment test of Brown et al. (2012). We place our results in the context of
the full sample of spin-orbit alignment measurements, finding that they provide
further support for previously established trends.


title:
Turbulent thermalization process in heavy-ion collisions at
  ultrarelativistic energies

abstract:
  The non-equilibrium evolution of heavy-ion collisions is studied in the limit
of weak coupling at very high energy employing lattice simulations of the
classical Yang-Mills equations. Performing the largest classical-statistical
simulations to date, we find that the dynamics of the longitudinally expanding
plasma becomes independent of the details of the initial conditions. After a
transient regime dominated by plasma instabilities and free streaming, the
subsequent space-time evolution is governed by a nonthermal fixed point, where
the system exhibits the self-similar dynamics characteristic of wave
turbulence. This allows us to distinguish between different kinetic scenarios
in the classical regime. Within the accuracy of our simulations, the scaling
behavior found is consistent with the ``bottom-up" thermalization scenario.


title:
Pairing in exotic neutron rich nuclei around the drip line and in the
  crust of neutron stars

abstract:
  Exotic and drip-line nuclei as well as nuclei immersed in a low density gas
of neutrons in the outer crust of neutron stars are systematically investigated
with respect to their neutron pairing properties. This is done using Skyrme
density-functional and different pairing forces such as a density-dependent
contact interaction and a separable form of a finite-range Gogny interaction.
Hartree-Fock-Bogoliubov and BCS theories are compared. It is found that neutron
pairing is reduced towards the drip line while overcast by strong shell
effects. Furthermore resonances in the continuum can have an important effect
counterbalancing the tendency of reduction and leading to a persistence of
pairing at the drip line. It is also shown that in these systems the difference
between HFB and BCS approaches can be qualitatively large.


title:
Single-site- and single-atom-resolved measurement of correlation
  functions

abstract:
  Correlation functions play an important role for the theoretical and
experimental characterization of many-body systems. In solid-state systems,
they are usually determined through scattering experiments whereas in
cold-gases systems, time-of-flight and in-situ absorption imaging are the
standard observation techniques. However, none of these methods allow the
in-situ detection of spatially resolved correlation functions at the
single-particle level. Here we give a more detailed account of recent advances
in the detection of correlation functions using in-situ fluorescence imaging of
ultracold bosonic atoms in an optical lattice. This method yields single-site
and single-atom-resolved images of the lattice gas in a single experimental
run, thus gaining direct access to fluctuations in the many-body system. As a
consequence, the detection of correlation functions between an arbitrary set of
lattice sites is possible. This enables not only the detection of two-site
correlation functions but also the evaluation of non-local correlations, which
originate from an extended region of the system and are used for the
characterization of quantum phases that do not possess (quasi-)long-range order
in the traditional sense.


title:
Resolvents, Poisson operators and scattering matrices on asymptotically
  hyperbolic and de Sitter spaces

abstract:
  We describe how the global operator induced on the boundary of an
asymptotically Minkowski space links two asymptotically hyperbolic spaces and
an asymptotically de Sitter space, and compute the scattering operator of the
linked problem in terms of the scattering operator of the constituent pieces.


title: High order symplectic partitioned Lie group methods

abstract:
  In this article, a unified approach to obtain symplectic integrators on T*G
from Lie group integrators on a Lie group G is presented. The approach is
worked out in detail for symplectic integrators based on
Runge--Kutta--Munthe-Kaas methods and Crouch--Grossman methods. These methods
can be interpreted as symplectic partitioned Runge--Kutta methods extended to
the Lie group setting in two different ways. In both cases, we show that it is
possible to obtain symplectic integrators of arbitrarily high order by this
approach.


title:
Can we allow linear dependencies in the dictionary in the sparse
  synthesis framework?

abstract:
  Signal recovery from a given set of linear measurements using a sparsity
prior has been a major subject of research in recent years. In this model, the
signal is assumed to have a sparse representation under a given dictionary.
Most of the work dealing with this subject has focused on the reconstruction of
the signal's representation as the means for recovering the signal itself. This
approach forced the dictionary to be of low coherence and with no linear
dependencies between its columns. Recently, a series of contributions that
focus on signal recovery using the analysis model find that linear dependencies
in the analysis dictionary are in fact permitted and beneficial. In this paper
we show theoretically that the same holds also for signal recovery in the
synthesis case for the l0- synthesis minimization problem. In addition, we
demonstrate empirically the relevance of our conclusions for recovering the
signal using an l1-relaxation.


title: Replicator dynamics with turnover of players

abstract:
  We study adaptive dynamics in games where players abandon the population at a
given rate, and are replaced by naive players characterized by a prior
distribution over the admitted strategies. We demonstrate how such process
leads macroscopically to a variant of the replicator equation, with an
additional term accounting for player turnover. We study how Nash equilibria
and the dynamics of the system are modified by this additional term, for
prototypical examples such as the rock-scissor-paper game and different classes
of two-action games played between two distinct populations. We conclude by
showing how player turnover can account for non-trivial departures from Nash
equilibria observed in data from lowest unique bid auctions.


title:
Electro/Magnetically Induced Controllable Rotation In Small-scale Liquid
  Flow

abstract:
  We study all the possibilities of producing rotating flow in an
incompressible fluid by electric and magnetic fields. We start with a general
theoretical basis and look for different configurations and set-ups which
electric/magnetic field and an electric current affect the vorticity of fluid
resulting in rotation on liquid flow. We assume steady-state conditions and
time-independent electric and magnetic fields as the external body torque.
Regarding the theoretical basis, we propose three experimental set-ups in which
by applying fields on a fluid, rotational vortices are produced: (a) a uniform
electric field and a uniform electric current, (b) a uniform electric current
and a non-uniform magnetic field, and (c) a non-uniform electric current and a
uniform magnetic field. The first case has been reported in detail named
"Liquid Film Motor". The two other cases are experimentally investigated here
for a cubic an cylindrical cells. The rotational velocity patterns are obtained
by PIV technique, and the results are discussed and justified by a preliminary
estimation based on the torque exerted by magnetic fields on electric currents.
From the log-log plot of angular velocity versus current, the non-linearity
factors of the rotational flow for cylindrical and rectangular geometries are
obtained.


title: Intermediate-Generalized Chaplygin Gas inflationary universe model

abstract:
  An intermediate inflationary universe model in the context of a generalized
Chaplygin gas is considered. For the matter we consider two different energy
densities; a standard scalar field and a tachyon field, respectively. In
general, we discuss the conditions of an inflationary epoch for these models.
We also, use recent astronomical observations from Wilkinson Microwave
Anisotropy Probe seven year data for constraining the parameters appearing in
our models.


title: Viterbi training in PRISM

abstract:
  VT (Viterbi training), or hard EM, is an efficient way of parameter learning
for probabilistic models with hidden variables. Given an observation $y$, it
searches for a state of hidden variables $x$ that maximizes $p(x,y \mid
\theta)$ by coordinate ascent on parameters $\theta$ and $x$. In this paper we
introduce VT to PRISM, a logic-based probabilistic modeling system for
generative models. VT improves PRISM in three ways. First VT in PRISM converges
faster than EM in PRISM due to the VT's termination condition. Second,
parameters learned by VT often show good prediction performance compared to
those learned by EM. We conducted two parsing experiments with probabilistic
grammars while learning parameters by a variety of inference methods, i.e.\ VT,
EM, MAP and VB. The result is that VT achieved the best parsing accuracy among
them in both experiments. Also we conducted a similar experiment for
classification tasks where a hidden variable is not a prediction target unlike
probabilistic grammars. We found that in such a case VT does not necessarily
yield superior performance. Third since VT always deals with a single
probability of a single explanation, Viterbi explanation, the exclusiveness
condition that is imposed on PRISM programs is no more required if we learn
parameters by VT.
  Last but not least we can say that as VT in PRISM is general and applicable
to any PRISM program, it largely reduces the need for the user to develop a
specific VT algorithm for a specific model. Furthermore since VT in PRISM can
be used just by setting a PRISM flag appropriately, it makes VT easily
accessible to (probabilistic) logic programmers. To appear in Theory and
Practice of Logic Programming (TPLP).


title: Analysing surveys of our Galaxy -- II. Determining the potential

abstract:
  We consider the problem of determining the Galaxy's gravitational potential
from a star catalogue. We show that orbit-based approaches to this problem
suffer from unacceptable numerical noise deriving from the use of only a finite
number of orbits. An alternative approach, which requires an ability to
determine the model's phase-space density at predetermined positions and
velocities, has a level of numerical noise that lies well below the intrinsic
uncertainty associated with the finite size of the catalogue analysed. A
catalogue of 10000 stars brighter than V=17 and distributed over the sky at
b>30 degrees enables us to determine the scaleheight of the disc that
contributes to the potential with an uncertainty below 20pc if the catalogue
gives proper motions, line-of-sight velocities and parallaxes with errors
typical of the Gaia Catalogue, rising to 36pc if only proper motions are
available. The uncertainty in the disc's scalelength is significantly smaller
than 0.25kpc.


title:
Spectral interferometric polarised coherent anti-Stokes Raman
  spectroscopy

abstract:
  We have developed an interferometric implementation of coherent anti-Stokes
Raman scattering (CARS) which enables broadband coherent Raman spectroscopy
free from non-resonant background (NRB), with a signal strength proportional to
concentration. Spectra encode mode symmetry information into the amplitude
response which can be directly compared to polarised spontaneous Raman spectra.
The method requires only passive polarisation optics and is suitable for a wide
range of laser linewidths and pulse durations


title: Dirac-Born-Infeld-Volkov-Akulov and Deformation of Supersymmetry

abstract:
  We deform the action and the supersymmetry transformations of the d=10 and
d=4 Maxwell supermultiplets so that at each order of the deformation the theory
has 16 Maxwell multiplet deformed supersymmetries as well as 16 Volkov-Akulov
type non-linear supersymmetries. The result agrees with the expansion in the
string tension of the explicit action of the Dirac-Born-Infeld model and its
supersymmetries, extracted from D9 and D3 superbranes, respectively. The
half-maximal Dirac-Born-Infeld models with 8 Maxwell supermultiplet deformed
supersymmetries and 8 Volkov-Akulov type supersymmetries are described by a new
class of d=6 vector branes related to chiral (2,0) supergravity, which we
denote as `Vp-branes'. We use a space-filling V5 superbrane for the d=6 model
and a V3 superbrane for the d=4 half-maximal Dirac-Born-Infeld (DBI) models. In
this way we present a completion to all orders of the deformation of the
Maxwell supermultiplets with maximal 16+16 supersymmetries in d=10 and 4, and
half-maximal 8+8 supersymmetries in d=6 and 4.


title: Hidden Supersymmetry May Imply Duality Invariance

abstract:
  We provide evidence that a particular hidden supersymmetry, when combined
with half-maximal deformed global supersymmetry, implies that the theory is
invariant under duality rotations of the vector and spinor fields. Based on a
complete 8+8 supersymmetric model constructed recently, we argue that this
hidden supersymmetry happens if and only if there is a Born-Infeld dependence
on the Maxwell field strength and a Volkov-Akulov dependence on the Goldstino,
up to local non-linear field redefinitions. We have tested our proposal for the
N=2 superfield action with manifest N=2 supersymmetry and hidden N=2
supersymmetry at the level W^{10}, the highest level of deformation known for
this model. We have established that it is N=2 self-dual, although the
self-duality was not required in the original construction of this model.
Highlighting the utility of considering duality-conserving sources of
deformation, we can verify this invariance directly in an alternate
construction of this very same action.


title: Decomposition of acyclic normal currents in a metric space

abstract:
  We prove that every acyclic normal one-dimensional real Ambrosio-Kirchheim
current in a Polish (i.e. complete separable metric) space can be decomposed in
curves, thus generalizing the analogous classical result proven by S. Smirnov
in Euclidean space setting.
  The same assertion is true for every complete metric space under a suitable
set-theoretic assumption.


title: On the generalized dimensions of multifractal eigenstates

abstract:
  Recently, based on heuristic arguments, it was conjectured that an intimate
relation exists between any multifractal dimensions, $D_q$ and $D_{q'}$, of the
eigenstates of critical random matrix ensembles: $D_{q'} \approx
qD_q[q'+(q-q')D_q]^{-1}$, $1\le q, q' \le 2$. Here, we verify this relation by
extensive numerical calculations on critical random matrix ensembles and extend
its applicability to $q<1/2$ but also to deterministic models producing
multifractal eigenstates and to generic multifractal structures. We also
demonstrate, for the scattering version of the power-law banded random matrix
model at criticality, that the scaling exponents $\sigma_q$ of the inverse
moments of Wigner delay times, $\bra \tau_{\tbox W}^{-q} \ket \propto
N^{-\sigma_q}$ where $N$ is the linear size of the system, are related to the
level compressibility $\chi$ as $\sigma_q\approx q(1-\chi)[1+q\chi]^{-1}$ for a
limited range of $q$; thus providing a way to probe level correlations by means
of scattering experiments.


title: Photonic Nonlinearities via Quantum Zeno Blockade

abstract:
  Realizing optical-nonlinear effects at a single-photon level is a highly
desirable but also extremely challenging task, because of both fundamental and
practical difficulties. We present an avenue to surmounting these difficulties
by exploiting quantum Zeno blockade in nonlinear optical systems. Considering
specifically a lithium-niobate microresonator, we find that a deterministic
phase gate can be realized between single photons with near-unity fidelity.
Supported by established techniques for fabricating and operating such devices,
our approach can provide an enabling tool for all-optical applications in both
classical and quantum domains.


title: Structure of metric cycles and normal one-dimensional currents

abstract:
  We prove that every one-dimensional real Ambrosio-Kirchheim normal current in
a Polish (i.e. complete separable metric) space can be naturally represented as
an integral of simpler currents associated to Lipschitz curves. As a
consequence a representation of every such current with zero boundary (i.e. a
cycle) as an integral of so-called elementary solenoids (which are, very
roughly speaking, more or less the same as asymptotic cycles introduced by S.
Schwartzman)is obtained. The latter result on cycles is in fact a
generalization of the analogous result proven by S. Smirnov for classical
Whitney currents in a Euclidean space. The same results are true for every
complete metric space under suitable set-theoretic assumptions.


title:
Common mode noise rejection properties of amplitude and phase noise in a
  heterodyne interferometer

abstract:
  High precision metrology systems based on heterodyne interferometry can
measure position and attitude of objects to accuracies of picometer and
nanorad, respectively. A frequently found feature of the general system design
is the subtraction of a reference phase from the phase of the position
interferometer, which suppresses low frequency common mode amplitude and phase
fluctuations occurring in volatile optical path sections shared by both, the
position and reference interferometer. Spectral components of the noise at
frequencies around or higher than the heterodyne frequency, however, are
generally transmitted into the measurement band and may limit the measurement
accuracy. Detailed analytical calculations complemented with Monte Carlo
simulations show that high frequency noise components may also be entirely
suppressed, depending on the relative difference of measurement and reference
phase, which may be exploited by corresponding design provisions. Whilst these
results are applicable to any heterodyne interferometer with certain design
characteristics, specific calculations and related discussions are given for
the example of the optical metrology system of the LISA Pathfinder mission to
space.


title:
Quasi-Rip universe induced by the fluid with inhomogeneous equation of
  state

abstract:
  We investigate a specific model for dark energy, which lead to the Quasi-Rip
cosmology. In the Quasi-Rip model, the equation of the state parameter $w$ is
less than -1 in the first stage, but then in the second stage is larger than
-1. The conditions for the appearance the Quasi-Rip in the terms of the
parameters equation of state are received.


title: Which Nonnegative Matrices Are Slack Matrices?

abstract:
  In this paper we characterize the slack matrices of cones and polytopes among
all nonnegative matrices. This leads to an algorithm for deciding whether a
given matrix is a slack matrix. The underlying decision problem is equivalent
to the polyhedral verification problem whose complexity is unknown.


title: Recent results from NA61/SHINE and NA49

abstract:
  Preliminary results on particle spectra and fluctuations in inelastic p+p
interactions measured by NA61/SHINE at the CERN SPS are presented and its
future ion program is discussed. We also show results on the excitation
functions of event-by-event particle ratio fluctuations in central Pb+Pb
collisions from NA49 using a novel approach. We found a dependence of the
results on phase space coverage which appears to explain the reported
difference between measurements of NA49 and those of STAR in central Au+Au
collisions.


title: The spin evolution of neutron stars with the superfluid core

abstract:
  We investigate the neutron stars spin evolution (breaking, inclination angle
evolution and radiative precession), taking into account the superfluidity of
the neutrons in the star core. The neutron star is treated as a two-component
system consisting of a "charged" component (including the crust and the core
protons, electrons and normal neutrons) and a core superfluid neutron
component. The components are supposed to interact through the mutual friction
force. We assume that the "charged" component rotates rigidly. The neutron
superfluid velocity field is calculated directly from linearized hydrodynamical
equations. It is shown that the superfluid core accelerates the evolution of
inclinaton angle and makes all pulsars evolve to either orthogonal or coaxial
state. However, rapid evolution seems to contradict the observation data.
Obtained results together with the observations may allow to examine the
superfluid models.


title:
Genetic Algorithm with Ensemble Learning for Detecting Community
  Structure in Complex Networks

abstract:
  Community detection in complex networks is a topic of considerable recent
interest within the scientific community. For dealing with the problem that
genetic algorithm are hardly applied to community detection, we propose a
genetic algorithm with ensemble learning (GAEL) for detecting community
structure in complex networks. GAEL replaces its traditional crossover operator
with a multi-individual crossover operator based on ensemble learning.
Therefore, GAEL can avoid the problems that are brought by traditional
crossover operator which is only able to mix string blocks of different
individuals, but not able to recombine clustering contexts of different
individuals into new better ones. In addition, the local search strategy, which
makes mutated node be placed into the community where most of its neighbors
are, is used in mutation operator. At last, a Markov random walk based method
is used to initialize population in this paper, and it can provide us a
population of accurate and diverse clustering solutions. Those diverse and
accurate individuals are suitable for ensemble learning based multi-individual
crossover operator. The proposed GAEL is tested on both computer-generated and
real-world networks, and compared with current representative algorithms for
community detection in complex networks. Experimental results demonstrate that
GAEL is highly effective at discovering community structure.


title:
On the transition temperature(s) of magnetized two-flavour holographic
  QCD

abstract:
  During heavy ion collisions, high temperatures and strong magnetic fields are
generated. We employ the gauge-gravity duality to study the N_f=2 QCD phase
diagram under these extreme conditions in the quenched approximation, in
particular we use the non-antipodal Sakai-Sugimoto model (SSM). We take the
different coupling of up and down flavours to the magnetic field into account
geometrically, resulting in a split of the chiral phase transition according to
flavour. We discuss the influence of the magnetic field on the chiral
temperatures -in physical GeV units- in terms of the choice of the confinement
scale in the model, extending hereby our elsewhere presented discussion of
fixing the non-antipodal SSM parameters to the deconfinement phase. The
flavour-dependent (T,L,eB) phase diagram, with variable asymptotic
brane-antibrane separation L, is also presented, as a direct generalization of
the known (T,L) phase diagram of the non-antipodal SSM at zero magnetic field.
In particular, for sufficiently small L we are probing a NJL-like boundary
field theory in which case we do find results very reminiscent of the
predictions in NJL models.


title:
Markov random walk under constraint for discovering overlapping
  communities in complex networks

abstract:
  Detection of overlapping communities in complex networks has motivated recent
research in the relevant fields. Aiming this problem, we propose a Markov
dynamics based algorithm, called UEOC, which means, 'unfold and extract
overlapping communities'. In UEOC, when identifying each natural community that
overlaps, a Markov random walk method combined with a constraint strategy,
which is based on the corresponding annealed network (degree conserving random
network), is performed to unfold the community. Then, a cutoff criterion with
the aid of a local community function, called conductance, which can be thought
of as the ratio between the number of edges inside the community and those
leaving it, is presented to extract this emerged community from the entire
network. The UEOC algorithm depends on only one parameter whose value can be
easily set, and it requires no prior knowledge on the hidden community
structures. The proposed UEOC has been evaluated both on synthetic benchmarks
and on some real-world networks, and was compared with a set of competing
algorithms. Experimental result has shown that UEOC is highly effective and
efficient for discovering overlapping communities.


title:
Construction of the continuous hull for the combinatorics of a regular
  pentagonal tiling of the plane

abstract:
  In the article "Construction of the discrete hull for the combinatorics of a
regular pentagonal tiling of the plane" we gave the construction of a discrete
hull for a combinatorial pentagonal tiling of the plane. In this paper, we give
the construction of a continuous hull for the same combinatorial tiling.


title: Mean Width of Random Perturbations of Random Polytopes

abstract:
  We prove some "high probability" results on the expected value of the mean
width for random perturbations of random polytopes. The random perturbations
are considered for Gaussian and $p$-stable random vectors, as well as uniform
distributions on $\ell_p^N$-balls and the unit sphere.


title: Interference alignment for the MIMO interference channel

abstract:
  We study vector space interference alignment for the MIMO interference
channel with no time or frequency diversity, and no symbol extensions. We prove
both necessary and sufficient conditions for alignment. In particular, we
characterize the feasibility of alignment for the symmetric three-user channel
where all users transmit along d dimensions, all transmitters have M antennas
and all receivers have N antennas, as well as feasibility of alignment for the
fully symmetric (M=N) channel with an arbitrary number of users.
  An implication of our results is that the total degrees of freedom available
in a K-user interference channel, using only spatial diversity from the
multiple antennas, is at most 2. This is in sharp contrast to the K/2 degrees
of freedom shown to be possible by Cadambe and Jafar with arbitrarily large
time or frequency diversity.
  Moving beyond the question of feasibility, we additionally discuss
computation of the number of solutions using Schubert calculus in cases where
there are a finite number of solutions.


title: On the Action Formalism of Time-dependent Density-functional Theory

abstract:
  The Runge-Gross [E. Runge, and E. K. U. Gross, Phys. Rev. Lett., 52, 997
(1984)] action functional of time-dependent density-functional theory leads to
a well-known causality paradox, i.e., a perturbation of the electronic density
in the future affects the response of the system in the present. This paradox
is known to be caused by an inconsistent application of the Dirac-Frenkel
variational principle. In view of the recent solutions to this problem, the
action functional employed by Runge and Gross in their formulation of
time-dependent density functional theory is analyzed in the context of the
Keldysh contour technique. The time-dependent electronic density, as well as
the concept of causality, are extended to the contour. We derive a variational
equation that obeys causality and relates the exchange-correlation potential
with its kernel, and the functional derivative of the exchange-correlation
action functional with respect to the density. It is shown that the adiabatic
local-density approximation is a consistent solution of this equation and that
the time-dependent optimized potential method can also be derived from it. The
formalism presented here can be used to find new approximations methods to the
exchange-correlation potential and avoid the causality dilemma.


title:
Full-Wave Iterative Image Reconstruction in Photoacoustic Tomography
  with Acoustically Inhomogeneous Media

abstract:
  Existing approaches to image reconstruction in photoacoustic computed
tomography (PACT) with acoustically heterogeneous media are limited to weakly
varying media, are computationally burdensome, and/or cannot effectively
mitigate the effects of measurement data incompleteness and noise. In this
work, we develop and investigate a discrete imaging model for PACT that is
based on the exact photoacoustic (PA) wave equation and facilitates the
circumvention of these limitations. A key contribution of the work is the
establishment of a procedure to implement a matched forward and backprojection
operator pair associated with the discrete imaging model, which permits
application of a wide-range of modern image reconstruction algorithms that can
mitigate the effects of data incompleteness and noise. The forward and
backprojection operators are based on the k-space pseudospectral method for
computing numerical solutions to the PA wave equation in the time domain. The
developed reconstruction methodology is investigated by use of both
computer-simulated and experimental PACT measurement data.


title:
A Sharp-Interface Active Penalty Method for the Incompressible
  Navier-Stokes Equations

abstract:
  The volume penalty method provides a simple, efficient approach for solving
the incompressible Navier-Stokes equations in domains with boundaries or in the
presence of moving objects. Despite the simplicity, the method is typically
limited to first order spatial accuracy. We demonstrate that one may achieve
high order accuracy by introducing an active penalty term. One key difference
from other works is that we use a sharp, unregularized mask function. We
discuss how to construct the active penalty term, and provide numerical
examples, in dimensions one and two. We demonstrate second and third order
convergence for the heat equation, and second order convergence for the
Navier-Stokes equations. In addition, we show that modifying the penalty term
does not significantly alter the time step restriction from that of the
conventional penalty method.


title: Charge and spin correlations of a Peierls insulator after a quench

abstract:
  Electron-phonon coupling plays a central role for time-dependent phenomena in
condensed matter, for example in photo-excitation experiments. We use the
continuous-time quantum Monte Carlo method to study the real-time evolution of
charge and spin correlation functions of a Peierls insulator after a quench to
a noninteracting Hamiltonian. This approach gives exact results, and fully
takes into account quantum phonon effects without relying on a Hilbert space
truncation. It is also free from a dynamical sign problem. The observed time
dependence is compared to free-fermion time evolution starting from a dimerized
state. Our exact results provide a benchmark for more realistic calculations,
and may be directly applicable to experiments with cold atoms or trapped ions.


title: Impulse Radio Ultra-Wideband Communication Over Free-Space Optical Links

abstract:
  A composite impulse radio ultra-wideband (IR-UWB) communication system is
presented. The proposed system model aims to transmit UWB pulses over several
kilometers through free-space optical (FSO) links and depending on the link
design, the electrical estimates of the FSO system can be directly used or
distributed to end-user through radio-frequency (RF) links over short ranges.
However, inhomogeneities on the FSO transmission path cause random fluctuations
in the received signal intensity and these effects induced by atmospheric
turbulence closely effect the system performance. Several distinct probability
distributions based on experimental measurements are used to characterize FSO
channels and using these probabilistic models, detection error probability
analysis of the proposed system for different link designs are carried out
under weak, moderate and strong turbulence conditions. The results of the
analysis show that depending on the atmospheric conditions, system performance
of the composite link can have high error floors due to the false estimates of
FSO link. The system performance can be improved by employing error control
coding techniques. One simple solution employing a convolutional encoder and
Viterbi decoder pair is also analyzed in this thesis. Another important system
parameter that is the average channel capacity of the FSO system is analyzed
under weak and moderate turbulence conditions. Theoretical derivations that are
verified via simulation results indicate a reliable high data rate
communication system that is effective in long distances.


title:
Beyond Reductionism Twice: No Laws Entail Biosphere Evolution, Formal
  Cause Laws Beyond Efficient Cause Laws

abstract:
  Newton set the stage for our view of how science should be done. We remain in
what I will call the `Newtonian Paradigm' in all of physics, including Newton,
Einstein, and Schrodinger. As I will show shortly, Newton invented and
bequeathed to us `efficient cause entailing laws' for the entire becoming of
the universe. With Laplace this became the foundation of contemporary
reductionism in which all that can happen in the world is due to efficient
cause entailing laws. More this framework stands as our dominant way to do
science. The Newtonian Paradigm has done enormous work in science, and helped
lead to the Industrial Revolution, and even our entry into Modernity.
  In this paper I propose to challenge the adequacy of the Newtonian Paradigm
on two ground: 1) For the evolution of the biosphere beyond the watershed of
life, we can formulate no efficient cause entailing laws that allow us to
deduce the evolution of the biosphere. A fortiori, the same holds for the
evolution of the economy, legal systems, social systems, and culture. Because I
have discussed this before with my colleagues Longo and Montevil (1,2) and
elsewhere, (3,4), my discussion of this first point will be rather brief. 2)
What I shall choose to call, after Aristotle's four causes, noted below, Formal
Cause Laws derived from specific `ensemble theories' tell us about the world.
But Formal Cause Laws are not reducible to efficient cause entailing laws of
the Newtonian Paradigm and, critically, have already, unnoticed, crept into
biology concerning the origin of life, and economics concerning economic
growth. Formal cause laws appear to be a new way to do science, independent of
efficient cause entailing laws. Thus Formal Cause laws can be independent of
any specific material substrate. This may bear on the sufficiency of
Materialism in our account of the world.


title: Sparse Factor Analysis for Learning and Content Analytics

abstract:
  We develop a new model and algorithms for machine learning-based learning
analytics, which estimate a learner's knowledge of the concepts underlying a
domain, and content analytics, which estimate the relationships among a
collection of questions and those concepts. Our model represents the
probability that a learner provides the correct response to a question in terms
of three factors: their understanding of a set of underlying concepts, the
concepts involved in each question, and each question's intrinsic difficulty.
We estimate these factors given the graded responses to a collection of
questions. The underlying estimation problem is ill-posed in general,
especially when only a subset of the questions are answered. The key
observation that enables a well-posed solution is the fact that typical
educational domains of interest involve only a small number of key concepts.
Leveraging this observation, we develop both a bi-convex maximum-likelihood and
a Bayesian solution to the resulting SPARse Factor Analysis (SPARFA) problem.
We also incorporate user-defined tags on questions to facilitate the
interpretability of the estimated factors. Experiments with synthetic and
real-world data demonstrate the efficacy of our approach. Finally, we make a
connection between SPARFA and noisy, binary-valued (1-bit) dictionary learning
that is of independent interest.


title:
Detecting the Harmonic Vibrations of Micro Amplitudes and Low
  Frequencies with Atomic Mach-Zehnder Interferometer

abstract:
  We study the effects of atomic beams harmonic vibrations of micro amplitudes
and low frequencies on the mean atomic numbers of the detectors in atomic
Mach-Zehnder interferometer, where the two atomic beams are in the same wave
surface and have the same phases. We propose a vibrant factor F to
quantitatively describe the effects of atomic beams vibrations. It shows that:
(i)the vibrant factor F depends on the relative vibrant displacements and the
initial phases rather than the absolute amplitudes, (ii)the factor F increases
with the increase of the initial phases, and (iii)the frequencies can be
derived from equal time interval measurement of the mean atomic numbers. These
results imply that it is possible to detect the vibrations of micro amplitudes
and low frequencies by measuring the variations of mean atomic numbers.


title: The Group of Units on an Affine Variety

abstract:
  The object of study is the group of units O^\ast(X) in the coordinate ring of
a normal affine variety X over an algebraically closed field k. Methods of
Galois cohomology are applied to those varieties that can be presented as a
finite cyclic cover of a rational variety. On a cyclic cover X \rightarrow A^m
of affine m-space over k such that the ramification divisor is irreducible and
the degree is prime, it is shown that O^\ast(X) is equal to k^\ast, the nonzero
scalars. The same conclusion holds, if X is a sufficiently general affine
hyperelliptic curve. If X has a projective completion such that the divisor at
infinity has r components, then sufficient conditions are given for
O^\ast(X)/k^\ast to be isomorphic to Z^(r-1).


title: Density Functionals that Recognize Covalent, Metallic, and Weak Bonds

abstract:
  Computationally-efficient semilocal approximations of density functional
theory at the level of the local spin density approximation (LSDA) or
generalized gradient approximation (GGA) poorly describe weak interactions. We
show improved descriptions for weak bonds (without loss of accuracy for strong
ones) from a newly-developed semilocal meta-GGA (MGGA), by applying it to
molecules, surfaces, and solids. We argue that this improvement comes from
using the right MGGA dimensionless ingredient to recognize all types of orbital
overlap.


title: Ferroelectricity in Single Crystal InMnO3

abstract:
  Single crystal synthesis, structure, electric polarization and heat capacity
measurements on hexagonal InMnO3 show that this small R ion in the RMnO3 series
is ferroelectric (space group P63cm). Structural analysis of this system
reveals a high degree of order within the MnO5 polyhedra but significant
distortions in the R-O bond distributions compared to the previously studied
materials. Point-charge estimates of the electric polarization yield an
electrical polarization of approximately 7.8 micro C/cm^2, 26% larger than the
well-studied YMnO3 system. This system with enhanced room temperature
polarization values may serve as a possible replacement for YMnO3 in device
application.


title:
The Brauer Group of an Affine Double Plane Associated to a Hyperelliptic
  Curve

abstract:
  For an affine double plane defined by an equation of the form z^2 = f, we
study the divisor class group and the Brauer group. Two cases are considered.
In the first case, f is a product of n linear forms in k[x,y] and X is
birational to a ruled surface P^1 x C, where C is rational if n is odd and
hyperelliptic if n is even. In the second case, f is the equation of an affine
hyperelliptic curve. On the open set where the cover is unramified, we compute
the groups of divisor classes, the Brauer groups, the relative Brauer group, as
well as all of the terms in he exact sequence of Chase, Harrison and Rosenberg.


title: Cortical Surface Co-Registration based on MRI Images and Photos

abstract:
  Brain shift, i.e. the change in configuration of the brain after opening the
dura mater, is a key problem in neuronavigation. We present an approach to
co-register intra-operative microscope images with pre-operative MRI to adapt
and optimize intra-operative neuronavigation. The tools are a robust
classification of sulci on MRI extracted cortical surfaces, guided user marking
of most prominent sulci on a microscope image, and the actual variational
registration method with a fidelity energy for 3D deformations of the cortical
surface combined with a higher order, linear elastica type prior energy.
Furthermore, the actual registration is validated on an artificial testbed with
known ground truth deformation and on real data of a neuro clinical patient.


title:
Deflation and augmentation techniques in Krylov subspace methods for the
  solution of linear systems

abstract:
  In this paper we present deflation and augmentation techniques that have been
designed to accelerate the convergence of Krylov subspace methods for the
solution of linear systems of equations. We review numerical approaches both
for linear systems with a non-Hermitian coefficient matrix, mainly within the
Arnoldi framework, and for Hermitian positive definite problems with the
conjugate gradient method.


title: Rational cohomology of the moduli spaces of pointed genus 1 curves

abstract:
  We give a combinatorial description of the rational cohomology of the moduli
spaces of pointed genus 1 curves with $n$ marked points and level $N$
structures. More precisely, we explicitly describe the $E_2$ term of the Leray
spectral sequence of the forgetful mapping
$\EuScript{M}_{1,n}(N)\to\EuScript{M}_{1,1}(N)$ and show that the result is
isomorphic to the rational cohomology of $\EuScript{M}_{1,n}(N)$ as a rational
mixed Hodge structure equipped with an action of the symmetric group
$\mathfrak{S}_n$. The classical moduli space $\EuScript{M}_{1,n}$ is the
particular case N=1.


title:
Singular value correlation functions for products of Wishart random
  matrices

abstract:
  Consider the product of $M$ quadratic random matrices with complex elements
and no further symmetry, where all matrix elements of each factor have a
Gaussian distribution. This generalises the classical Wishart-Laguerre Gaussian
Unitary Ensemble with M=1. In this paper we first compute the joint probability
distribution for the singular values of the product matrix when the matrix size
$N$ and the number $M$ are fixed but arbitrary. This leads to a determinantal
point process which can be realised in two different ways. First, it can be
written as a one-matrix singular value model with a non-standard Jacobian, or
second, for $M\geq2$, as a two-matrix singular value model with a set of
auxiliary singular values and a weight proportional to the Meijer $G$-function.
For both formulations we determine all singular value correlation functions in
terms of the kernels of biorthogonal polynomials which we explicitly construct.
They are given in terms of hypergeometric and Meijer $G$-functions,
generalising the Laguerre polynomials. Our investigation was motivated from
applications in telecommunication of multi-layered scattering MIMO channels. We
present the ergodic mutual information for finite-$N$ for such a channel model
with $M-1$ layers of scatterers as an example.

categories: math-ph cond-mat.stat-mech cs.IT math.IT math.MP


title: Gravitational vacuum polarization phenomena due to the Higgs field

abstract:
  In the standard model the mass of elementary particles is considered as a
dynamical property emerging from their interaction with the Higgs field. We
show that this assumption implies peculiar deviations from the law of universal
gravitation in its distance and mass dependence, as well as from the
superposition principle. The experimental observation of the predicted
deviations from the law of universal gravitation seems out of reach. However,
we argue that a new class of experiments aimed at studying the influence of
surrounding masses on the gravitational force - similar to the ones performed
by Quirino Majorana almost a century ago - could be performed to test the
superposition principle and to give direct limits on the presence of
non-minimal couplings between the Higgs field and the spacetime curvature. From
the conceptual viewpoint, the violation of the superposition principle for
gravitational forces due to the Higgs field creates a conflict with the notion
that gravitational potentials, as assumed in Newtonian gravitation or in
post-Newtonian parameterizations of metric theories, are well-defined concepts
to describe gravity in their non-relativistic limit.


title: Light stops emerging in WW cross section measurements?

abstract:
  Recent ATLAS and CMS measurements show a slight excess in the WW cross
section measurement. While still consistent with the Standard Model within 1-2
sigma, the excess could be also a first hint of physics beyond the Standard
Model. We argue that this effect could be attributed to the production of
scalar top quarks within supersymmetric models. The stops of mstop_1 ~ 200 GeV
has the right pair-production cross section and under some assumptions can
significantly contribute to the final state of two leptons and missing energy.
We scan this region of parameter space to identify stop mass range preferred by
the WW cross section measurements. Taking one sample benchmark point we show
that it can be consistent with low energy observables and Higgs sector
measurements and propose a method to distinguish supersymmetric signal from the
Standard Model contribution.