title: Synchronization theory of microwave induced zero-resistance states

abstract:
  We develop the synchronization theory of microwave induced zero-resistance
states (ZRS) for two-dimensional electron gas in a magnetic field. In this
theory the dissipative effects lead to synchronization of cyclotron phase with
driving microwave phase at certain resonant ratios between microwave and
cyclotron frequencies. This synchronization produces stabilization of electron
transport along edge channels and at the same time it gives suppression of
dissipative scattering on local impurities and dissipative conductivity in the
bulk, thus creating the ZRS phases at that frequency ratios. The electron
dynamics along edge and around circular disk impurity is well described by the
Chirikov standard map. The theoretical analysis is based on extensive numerical
simulations of classical electron transport in a strongly nonlinear regime. We
also discuss the value of activation energy obtained in our model and the
experimental signatures that could establish the synchronization origin of ZRS.


title:
"Ping-pong" electron transfer. II. Multiple reflections of the Loschmidt
  echo and the wave function trapping by an acceptor

abstract:
  This paper continues the preceding paper on the problem of quantum dynamics
on the lattice. Firstly we consider the multiple reflections of the wave
function (Loschmidt echo). The phenomenon of wave function concentration on the
impurity site after reflections is found. The solution representing the total
amplitude $a(t)$ is obtained as the series in terms of partial amplitudes
$a_k(t)$. The contribution of $k$th partial amplitude becomes dominant only
after $k$th reflection from the lattice end. An excellent agreement between
analytical and accurate numerical results is obtained. Next problem, -- wave
packet trapping by defects, is solved by numerical simulation. Analytical
expressions are derived in few cases allowing to estimate the quantum
efficiency of charge transfer. Obtained results can qualitatively explain
recent experiments on the highly efficient charge transport in olygonucleotides
and polypeptides.


title:
Optical polarization anisotropy, intrinsic Stark effect and Coulomb
  effects on the lasing characteristics of [0001]-oriented GaN/Al0.3Ga0.7N
  quantum wells

abstract:
  We present a theoretical investigation of space separated electron and hole
distributions, which consists in the self-consistent solving of the Schrodinger
equations for electrons and holes and the Poisson equation. The results are
illustrated for the GaN/Al0.3Ga0.7N quantum well. The optical gain spectrum in
a [0001]-oriented GaN/Al0.3Ga0.7N quantum well in the ultraviolet region is
calculated. It is found that both the matrix elements of optical transitions
from the heavy hole band and the optical gain spectrum have only the strict x
(or y) light polarization. We present studies of the influence of the
confinement of wave functions on the optical gain which implicitly depends on
the built-in electric field calculated to be 2.3 MV/cm. Whereas the structures
with narrow well widths exhibit the usual development of the light gain maximum
almost without shifting the spectral region, a significant blueshift of the
gain maximum is found with increase in the plasma density for wider quantum
wells. This blueshift is ascribed to the interplay between the screening of a
strain-induced piezoelectric field and the bandstructure. A large Sommerfeld or
Coulomb enhancement is present in the quantum well.


title:
Direct observation of particles with energy >10 MeV/u from laser-induced
  fusion in ultra-dense deuterium

abstract:
  Nuclear fusion in ultra-dense deuterium D(-1) induced by 0.2 J pulses with 5
ns pulse length ejects ions with energies in the MeV range. The ns-resolved
signal to a collector can be observed directly on an oscilloscope, showing ions
arriving with energies in the range 2-14 MeV u-1 at flight times 12-100 ns,
mainly protons from the fusion process and deuterons ejected by proton
collisions. Electrons and photons give almost no contribution to the fast
signal. The observed signal at several mA peak current corresponds to 1x10^13
particles released per laser shot and to an energy release > 1 J assuming
isotropic formation and average particle energy of 3 MeV as observed. A movable
slit close to the laser target gives spatial resolution of the signal
generation, showing almost only fast ions from the point of laser impact and
penetrating photons from the plasma outside the laser impact point. The initial
photon pulse from the fusion process is observed by a photomultiplier detector
on-line.


title:
Balanced and optimal bianisotropic particles: Maximizing power extracted
  from electromagnetic fields

abstract:
  Here we introduce the concept of "optimal particles" for strong interactions
with electromagnetic fields. We assume that a particle occupies a given
electrically small volume in space and study the required optimal relations
between the particle polarizabilities. In these optimal particles, the
inclusion shape and material are chosen so that the particles extract the
maximum possible power from given incident fields. It appears that for
different excitation scenarios the optimal particles are bianisotropic chiral,
omega, moving, and Tellegen particles. The optimal dimensions of the resonance
canonical chiral and omega particles are found analytically. Such optimal
particles have extreme properties in scattering (for example, zero
backscattering or invisibility). Planar arrays of optimal particles possess
extreme properties in reflection and transmission (e.g., total absorption or
magnetic-wall resonance), and volumetric composites of optimal particles
realize, for example, such extreme materials as the chiral nihility medium.


title: Hartree-Fock problem of an electron-hole pair in the quantum well GaN

abstract:
  We present microscopic calculations of the absorption spectra for
GaN/Al(x)Ga(1-x)N quantum well systems. Whereas the quantum well structures
with the parabolic law of dispersion exhibit the usual bleaching of an exciton
resonance without shifting a spectral position, the significant red-shift of an
exciton peak is found with increasing the electron-hole gas density for a
wurtzite quantum well. The energy of the exciton resonance for a wurtzite
quantum well is found. The obtained results can be explained by the influence
of the valence band structure on quantum confinement effects. The optical gain
spectrum in the Hartree-Fock approximation and the Sommerfeld enhancement are
calculated. A red shift of the gain spectrum in the Hartree-Fock approximation
with respect to the Hartree gain spectrum is found.


title:
A computational tool for comparing all linear PDE solvers -- Optimal
  methods are meshless

abstract:
  The paper starts out with a computational technique that allows to compare
all linear methods for PDE solving that use the same input data. This is done
by writing them as linear recovery formulas for solution values as linear
combinations of the input data. Calculating the norm of these reproduction
formulas on a fixed Sobolev space will then serve as a quality criterion that
allows a fair comparison of all linear methods with the same inputs, including
finite-element, finite-difference and meshless local Petrov-Galerkin
techniques. A number of illustrative examples will be provided. As a byproduct,
it turns out that a unique error--optimal method exists. It necessarily
outperforms any other competing technique using the same data, e.g. those just
mentioned, and it is necessarily meshless, if solutions are written "entirely
in terms of nodes" (Belytschko et. al. 1996). On closer inspection, it turns
out that it coincides with {\em symmetric meshless collocation} carried out
with the kernel of the Hilbert space used for error evaluation, e.g. with the
kernel of the Sobolev space used. This technique is around since at least 1998,
but its optimality properties went unnoticed, so far.


title: Extraordinary Magnification of the Ordinary Type Ia Supernova PS1-10afx

abstract:
  Recently, Chornock and co-workers announced the Pan-STARRS discovery of a
transient source reaching an apparent peak luminosity of ~4x10^44 erg s^-1. We
show that the spectra of this transient source are well fit by normal Type Ia
supernova (SNIa) templates. The multi-band colors and light-curve shapes are
also consistent with normal SNeIa at the spectroscopically determined redshift
of z=1.3883; however, the observed flux is a constant factor of ~30 times too
bright in each band over time as compared to the templates. At minimum, this
shows that the peak luminosities inferred from the light-curve widths of some
SNeIa will deviate significantly from the established, empirical relation used
by cosmologists. We argue on physical grounds that the observed fluxes do not
reflect an intrinsically luminous SNIa, but rather PS1-10afx is a normal SNIa
whose flux has been magnified by an external source. The only known
astrophysical source capable of such magnification is a gravitational lens.
Given the lack of obvious lens candidates, such as galaxy clusters, in the
vicinity, we further argue that the lens is a supermassive black hole or a
comparatively low-mass dark matter halo. In this case, the lens continues to
magnify the underlying host galaxy light. If confirmed, this discovery could
impact a broad range of topics including cosmology, gamma-ray bursts, and dark
matter halos.


title:
Experimental constraints on the uncoupled Galileon model from SNLS3 data
  and other cosmological probes

abstract:
  The Galileon model is a modified gravity theory that may provide an
explanation for the accelerated expansion of the Universe. This model does not
suffer from instabilities or ghost problems (normally associated with
higher-order derivative theories), restores local General Relativity -- thanks
to the Vainshtein screening effect -- and predicts late time acceleration of
the expansion. In this paper, we derive a new definition of the Galileon
parameters that allows us to avoid having to choose initial conditions for the
Galileon field, and then test this model against precise measurements of the
cosmological distances and the rate of growth of cosmic structures. We observe
a small tension between the constraints set by growth data and those from
distances. However, we find that the Galileon model remains consistent with
current observations and is still competitive with the \Lambda CDM model,
contrary to what was concluded in recent publications.


title: Acquaintance Time of a Graph

abstract:
  We define the following parameter of connected graphs. For a given graph $G$
we place one agent in each vertex of $G$. Every pair of agents sharing a common
edge is declared to be acquainted. In each round we choose some matching of $G$
(not necessarily a maximal matching), and for each edge in the matching the
agents on this edge swap places. After the swap, again, every pair of agents
sharing a common edge become acquainted, and the process continues. We define
the \emph{acquaintance time} of a graph $G$, denoted by $AC(G)$, to be the
minimal number of rounds required until every two agents are acquainted.
  We first study the acquaintance time for some natural families of graphs
including the path, expanders, the binary tree, and the complete bipartite
graph. We also show that for all positive integers $n$ and $k \leq n^{1.5}$
there exists an $n$-vertex graph $G$ such that $AC(G) =\Theta(k)$. We also
prove that for all $n$-vertex connected graphs $G$ we have $AC(G) =
O\left(\frac{n^2}{\log(n)/\log\log(n)}\right)$, improving the $O(n^2)$ trivial
upper bound achieved by sequentially letting each agent perform depth-first
search along a spanning tree of $G$.
  Studying the computational complexity of this problem, we prove that for any
constant $t \geq 1$ the problem of deciding that a given graph $G$ has $AC(G)
\leq t$ or $AC(G) \geq 2t$ is $\mathcal{NP}$-complete. That is, $AC(G)$ is
$\mathcal{NP}$-hard to approximate within multiplicative factor of 2, as well
as within any additive constant factor.
  On the algorithmic side, we give a deterministic algorithm that given a graph
$G$ with $AC(G)=1$ finds a ${\lceil n/c\rceil}$-rounds strategy for
acquaintance in time $n^{c+O(1)}$. We also design a randomized polynomial time
algorithm that given a graph $G$ with $AC(G)=1$ finds with high probability an
$O(\log(n))$-rounds strategy for acquaintance.


title: Minimum length path decompositions

abstract:
  We consider a bi-criteria generalization of the pathwidth problem, where, for
given integers $k,l$ and a graph $G$, we ask whether there exists a path
decomposition $\cP$ of $G$ such that the width of $\cP$ is at most $k$ and the
number of bags in $\cP$, i.e., the \emph{length} of $\cP$, is at most $l$.
  We provide a complete complexity classification of the problem in terms of
$k$ and $l$ for general graphs. Contrary to the original pathwidth problem,
which is fixed-parameter tractable with respect to $k$, we prove that the
generalized problem is NP-complete for any fixed $k\geq 4$, and is also
NP-complete for any fixed $l\geq 2$. On the other hand, we give a
polynomial-time algorithm that, for any (possibly disconnected) graph $G$ and
integers $k\leq 3$ and $l>0$, constructs a path decomposition of width at most
$k$ and length at most $l$, if any exists.
  As a by-product, we obtain an almost complete classification of the problem
in terms of $k$ and $l$ for connected graphs. Namely, the problem is
NP-complete for any fixed $k\geq 5$ and it is polynomial-time for any $k\leq
3$. This leaves open the case $k=4$ for connected graphs.


title:
A simple proof of the formula for the Betti numbers of the
  quasihomogeneous Hilbert schemes

abstract:
  In a recent paper the first two authors proved that the generating series of
the Poincare polynomials of the quasihomogeneous Hilbert schemes of points in
the plane has a simple decomposition in an infinite product. In this paper we
give a very short geometrical proof of that formula.


title:
Approximations of certain classes of functions of several variables by
  greedy approximants in the integral metrics

abstract:
  We find the exact order estimates of the approximations of the classes ${\cal
F}_{q,r}^{\psi}$ of functions of several variables by greedy approximants in
the integral metric. We also obtain the exact order estimates of the best
$n$-term orthogonal trigonometric approximations of the classes ${\cal
F}_{q,r}^{\psi}$ in the integral metric.


title:
Solar neutrino physics oscillations: Sensitivity to the electronic
  density in the Sun's core

abstract:
  Solar neutrinos coming from different nuclear reactions are now detected with
a high statistics. Consequently, an accurate spectroscopic analysis of the
neutrino fluxes arriving on the Earth's detectors become available, in the
context of neutrino oscillations. In this work, we explore the possibility of
using this information to infer the radial profile of the electronic density in
the solar core. So, we discuss the constraints on the Sun's density and
chemical composition that can be determined from solar neutrino observations.
This approach constitutes an independent and alternative diagnostic to the
helioseismic investigations already done. The direct inversion method, that we
propose to get the radial solar electronic density profile, is almost
independent of the solar model.


title:
$\eta$-invariant and a problem of B\'erard-Bergery on the existence of
  closed geodesics

abstract:
  We use the $\eta$-invariant of Atiyah-Patodi-Singer to compute the
Eells-Kuiper invariant for the Eells-Kuiper quaternionic projective plane. By
combining with a known result of B\'erard-Bergery, it shows that every
Eells-Kuiper quaternionic projective plane carries a Riemannian metric such
that all geodesics passing through a certain point are simply closed and of the
same length.


title:
On Multi-dimensional Compressible Flows of Nematic Liquid Crystals with
  Large Initial Energy in a Bounded Domain

abstract:
  We study the global existence of weak solutions to a multi-dimensional
simplified Ericksen-Leslie system for compressible flows of nematic liquid
crystals with large initial energy in a bounded domain $\Omega\subset
\mathbb{R}^N$, where N=2 or 3. By exploiting a maximum principle, Nirenberg's
interpolation inequality and a smallness condition imposed on the $N$-th
component of initial direction field $\mf{d}_0$ to overcome the difficulties
induced by the supercritical nonlinearity $|\nabla{\mathbf d}|^2{\mathbf d}$ in
the equations of angular momentum, and then adapting a modified
three-dimensional approximation scheme and the weak convergence arguments for
the compressible Navier-Stokes equations, we establish the global existence of
weak solutions to the initial-boundary problem with large initial energy and
without any smallness condition on the initial density and velocity.


title: New Cosmological Solutions in Nonlocal Modified Gravity

abstract:
  We consider some cosmological aspects of nonlocal modified gravity with
$\Lambda$ term, where nonlocality is of the type $R \mathcal{F}(\Box) R$. Using
ansatz of the form $\Box R = r R +s,$ we find a few a(t) nonsingular bounce
cosmological solutions for all three values of spatial curvature parameter k.
We also discuss this modified gravity model from F(R) theory point of view.


title:
Processes in current sheets responsible for fast energy conversion in
  the magnetospheric collisionless plasma

abstract:
  Dynamics of the magnetospheric plasma configuration intrinsically features
intermittent slow and fast phases. The fast transition is a nonlinear process,
loss of equilibrium which ends up the slow quasi-static evolution. The process
is analysed as a dynamical bifurcation. It appears when marginal stability
state is reached in the course of that evolution, either for tearing mode or
for ballooning mode disturbances. The resulting force imbalance leads to
spontaneous formation of nonlinear kinetic thin current structures. Those are
either a pair of slow collisionless shocks or a specific anisotropic thin
current sheet embedded in a thicker plasma sheet structure. Both are the sites
of intense energy conversion, and they implement fast magnetic reconnection in
the magnetospheric collisionless plasma.


title: Endless self-avoiding walks

abstract:
  We introduce a self-avoiding walk model for which end-effects are completely
eliminated. We enumerate the number of these walks for various lattices in
dimensions two and three, and use these enumerations to study the properties of
this model. We find that endless self-avoiding walks have the same connective
constant as self-avoiding walks, and the same Flory exponent $\nu$. However,
there is no power law correction to the exponential number growth for this new
model, i.e. the critical exponent $\gamma = 1$ exactly. In addition, we have
convincing numerical evidence to support the hypothesis that the amplitude for
the number growth is a universal quantity, and somewhat weaker evidence which
suggests that the number growth has no analytic corrections to scaling. The
technique by which end-effects are eliminated may be generalised to other
models of polymers such as interacting self-avoiding walks.


title:
Preliminary study of kaonic deuterium X-rays by the SIDDHARTA experiment
  at DAFNE

abstract:
  The study of the KbarN system at very low energies plays a key role for the
understanding of the strong interaction between hadrons in the strangeness
sector. At the DAFNE electron-positron collider of Laboratori Nazionali di
Frascati we studied kaonic atoms with Z=1 and Z=2, taking advantage of the
low-energy charged kaons from Phi-mesons decaying nearly at rest. The SIDDHARTA
experiment used X-ray spectroscopy of the kaonic atoms to determine the
transition yields and the strong interaction induced shift and width of the
lowest experimentally accessible level (1s for H and D and 2p for He). Shift
and width are connected to the real and imaginary part of the scattering
length. To disentangle the isospin dependent scattering lengths of the
antikaon-nucleon interaction, measurements of Kp and of Kd are needed. We
report here on an exploratory deuterium measurement, from which a limit for the
yield of the K-series transitions was derived: Y(K_tot)<0.0143 and
Y(K_alpha)<0.0039 (CL 90%). Also, the upcoming SIDDHARTA-2 kaonic deuterium
experiment is introduced.


title:
Molecular motors robustly drive active gels to a critically connected
  state

abstract:
  Living systems often exhibit internal driving: active, molecular processes
drive nonequilibrium phenomena such as metabolism or migration. Active gels
constitute a fascinating class of internally driven matter, where molecular
motors exert localized stresses inside polymer networks. There is evidence that
network crosslinking is required to allow motors to induce macroscopic
contraction. Yet a quantitative understanding of how network connectivity
enables contraction is lacking. Here we show experimentally that myosin motors
contract crosslinked actin polymer networks to clusters with a scale-free size
distribution. This critical behavior occurs over an unexpectedly broad range of
crosslink concentrations. To understand this robustness, we develop a
quantitative model of contractile networks that takes into account network
restructuring: motors reduce connectivity by forcing crosslinks to unbind.
Paradoxically, to coordinate global contractions, motor activity should be low.
Otherwise, motors drive initially well-connected networks to a critical state
where ruptures form across the entire network.


title:
Asymptotic Formula for a General Double-Bounded Custom-Sided Likelihood
  Based Test Statistic

abstract:
  This paper presents the asymptotic distributions of a general
likelihood-based test statistic, derived using results of Wilks and Wald. The
general form of the test statistic incorporates the test statistics and
associated asymptotic formulae previously derived by Cowan, Cranmer, Gross and
Vitells, which are seen to be special cases of the likelihood-based test
statistic described here.


title: Generalized Weyl quantization on the cylinder and quantum phase

abstract:
  Generalized Weyl quantization formalism for the cylindrical phase space $S^1
\times \mathbb{R}^1$ is developed. It is shown that the quantum observables
relevant to the phase of linear harmonic oscillator or electromagnetic field
can be represented within this formalism by the self-adjoint operators on the
Hilbert space $L^2(S^1)$.


title: Fermionic Casimir densities in anti-de Sitter spacetime

abstract:
  The fermionic condensate and vacuum expectation value of the energy-momentum
tensor, for a massive fermionic field on the background of anti-de Sitter
spacetime, in the geometry of two parallel boundaries with bag boundary
conditions, are investigated. Vacuum expectation values, expressed as series
involving the eigenvalues of the radial quantum number, are neatly decomposed
into boundary-free, single-boundary-induced, and second-boundary-induced parts,
with the help of the generalized Abel-Plana summation formula. In this way, the
renormalization procedure is very conveniently reduced to the one corresponding
to boundary-free AdS spacetime. The boundary-induced contributions to the
fermionic condensate and to the vacuum expectation value of the energy density
are proven to be everywhere negative. The vacuum expectation values are
exponentially suppressed at distances from the boundaries much larger than the
curvature radius of the AdS space. Near the boundaries, effects related with
the curvature of the background spacetime are shown to be subdominant and, to
leading order, all known results for boundaries in the Minkowski bulk are
recovered. Zeta function techniques are successfully used for the evaluation of
the total vacuum energy in the region between the boundaries. It is proven that
the resulting interaction forces between them are attractive and that, for
large separations, they also decay exponentially. Finally, our results are
extended and explicitly translated to fermionic Casimir densities in braneworld
scenarios of Randall-Sundrum type.


title: Experimental evidence for electric surface resistance in niobium

abstract:
  Identifying the loss mechanisms of niobium cavities enables an accurate
determination of applications for future accelerator projects and points to
research topics required to mitigate current limitations. For several cavities
an increasing surface resistance above a threshold field, saturating at higher
field has been observed. Measurements on samples give evidence that this effect
is caused by the surface electric field. The measured temperature and frequency
dependence is consistent with a model that accounts for these losses by
interface tunnel exchange between localized states in oxides formed along grain
boundaries and the adjacent superconductor.


title:
Spectral Radius Inequalities for Functions of Operators Defined by Power
  Series

abstract:
  By the help of power series f we can naturally construct another power series
that has as coefficients the absolute values of the coefficients of f.
Utilising these functions we prove some inequalities for the spectral radius of
the bounded linear operator f(T) on a complex Hilbert space and some functions
of its norm. The case of two commuting operators is also investigated.


title: Flat Rotational Surface with Pointwise 1-typeGauss map in E4

abstract:
  In this paper we study general rotational surfaces in the 4- dimensional
Euclidean space E4 and give a characterization of flat general rotation surface
with pointwise 1-type Gauss map. Also, we show that a non-planar flat general
rotation surface with pointwise 1-type Gauss map is a Lie group if and only if
it is a Clifford torus.


title: Randomized online computation with high probability guarantees

abstract:
  We study the relationship between the competitive ratio and the tail
distribution of randomized online minimization problems. To this end, we define
a broad class of online problems that includes some of the well-studied
problems like paging, k-server and metrical task systems on finite metrics, and
show that for these problems it is possible to obtain, given an algorithm with
constant expected competitive ratio, another algorithm that achieves the same
solution quality up to an arbitrarily small constant error a with high
probability; the "high probability" statement is in terms of the optimal cost.
Furthermore, we show that our assumptions are tight in the sense that removing
any of them allows for a counterexample to the theorem. In addition, there are
examples of other problems not covered by our definition, where similar high
probability results can be obtained.


title: Collapse and Revival and Cat States with an N Spin System

abstract:
  We discuss collapse and revival of Rabi oscillations in a system comprising a
qubit and a "big spin" (made of N qubits, or spin-1/2 particles). We
demonstrate a regime of behaviour analogous to conventional collapse and
revival for a qubit-field system, employing spin coherent states for the
initial state of the big spin. These dynamics can be used to create a
"Schrodinger cat" state of the big spin. Even for relatively small values of N,
states with significant potential for quantum metrology applications can
result, giving sensitivity approaching the Heisenberg limit.


title:
$\mu-H$ Lamb shift: dispersing the nucleon-excitation uncertainty with a
  finite energy sum rule

abstract:
  We assess the two-photon exchange contribution to the Lamb shift in muonic
hydrogen with forward dispersion relations. The subtraction constant $\bar
T(0,Q^2)$ that is necessary for a dispersive evaluation of the forward
doubly-virtual Compton amplitude, through a finite energy sum rule, is related
to the fixed J=0 pole generalized to the case of virtual photons. We evaluated
this sum rule using excellent virtual photoabsorption data that are available.
We find that the "proton polarizability correction" to the Lamb shift in muonic
hydrogen is $-(40\pm5)\mu$eV. We conclude that nucleon structure-dependent
uncertainty by itself is unlikely to resolve the large (300$\mu$eV) discrepancy
between direct measurement of the Lamb shift in $\mu H$ and expectations based
on conventional Hydrogen measurements.


title:
NbSi nanowire quantum-phase-slip circuits: dc supercurrent blockade,
  microwave measurements and thermal analysis

abstract:
  We present a detailed report of microwave irradiation of ultra-narrow
superconducting nanowires. In our nanofabricated circuits containing a
superconducting NbSi nanowire, a dc blockade of current flow was observed at
low temperatures below a critical voltage Vc, a strong indicator of the
existence of quantum phase-slip (QPS) in the nanowire. We describe the results
of applying microwaves to these samples, using a range of frequencies and both
continuous-wave and pulsed drive, in order to search for dual Shapiro steps
which would constitute an unambiguous demonstration of quantum phase-slip. We
observed no steps, and our subsequent thermal analysis suggests that the
electron temperature in the series CrO resistors was significantly elevated
above the substrate temperature, resulting in sufficient Johnson noise to wash
out the steps. To understand the system and inform future work, we have
constructed a numerical model of the dynamics of the circuit for dc and ac bias
(both continuous wave and pulsed drive signals) in the presence of Johnson
noise. Using this model, we outline important design considerations for device
and measurement parameters which should be used in any future experiment to
enable the observation of dual Shapiro steps at experimentally accessible
temperatures and thus lead to the development of a QPS-based quantum current
standard.


title:
Characterizations of the Quaternionic Bertrand Curve in Euclidean Space
  E4

abstract:
  In [18], L. R. Pears proved that Bertrand curves in E-n(n > 3) are degenerate
curves. This result restate in [16] by Matsuda and Yorozu. They proved that
there is no special Bertrand curves in E-n(n > 3) and they define new kind of
Bertrand curves called (1, 3)-type Bertrand curves in 4-dimensional Euclidean
space. In this study, we define a quaternionic Bertrand curve ?(4) in Euclidean
space E4 and investigate its properties for two cases. In the first case; we
consider quaternionic Bertrand curve in the Euclidean space E4 for r-K = 0
where r is the torsion of the spatial quaternionic curve ?; K is the principal
curvature of the quaternionic curve ?(4): And then, in the other case, we prove
that there is no quaternionic Bertrand curve in the Euclidean space E4 for r -
K = 0: So, we give an idea of quaternionic Bertrand curve which we call
quaternionic (N - B2) Bertrand curve in the Euclidean space E4 by using the
similar method in [16] and we give some characterizations of such curves.


title:
Four-dimensional Causal Dynamical Triangulations and an effective
  transfer matrix

abstract:
  Causal Dynamical Triangulations is a background independent approach to
quantum gravity. We show that there exists an effective transfer matrix labeled
by the scale factor which properly describes the evolution of the quantum
universe. In this framework no degrees of freedom are frozen, but, the obtained
effective action agrees with the minisuperspace model.


title: Extracting work from quantum systems

abstract:
  We consider the task of extracting work from quantum systems in the resource
theory perspective of thermodynamics, where free states are arbitrary thermal
states, and allowed operations are energy conserving unitary transformations.
Taking as our work storage system a 'weight' we prove the second law and then
present simple protocols which extract average work equal to the free energy
change of the system - the same amount as in classical thermodynamics.
Crucially, for systems in 'classical' states (mixtures of energy eigenstates)
our protocol works on a single copy of the system. This is in sharp contrast to
previous results, which showed that in case of almost-deterministic work
extraction, collective actions on multiple copies are necessary to extract the
free energy. This establishes the fact that free energy is a meaningful notion
even for individual systems in classical states. However, for non-classical
states, where coherences between energy levels exist, we prove that collective
actions are necessary, so long as no external sources of coherence are used.


title:
Search for new physics in final states with a lepton and missing
  transverse energy in pp collisions at the LHC

abstract:
  This Letter describes the search for an enhanced production rate of events
with a charged lepton and a neutrino in high-energy pp collisions at the LHC.
The analysis uses data collected with the CMS detector, with an integrated
luminosity of 5.0 inverse femtobarns at sqrt(s) = 7 TeV, and a further 3.7
inverse femtobarns at sqrt(s) = 8 TeV. No evidence is found for an excess. The
results are interpreted in terms of limits on a heavy charged gauge boson (W')
in the sequential standard model, a split universal extra dimension model, and
contact interactions in the helicity-nonconserving model. For the last, values
of the binding energy below 10.5 (8.8) TeV in the electron (muon) channel are
excluded at a 95% confidence level. Interpreting the ell nu final state in
terms of a heavy W' with standard model couplings, masses below 2.90 TeV are
excluded.


title: Polarized extended Ly-alpha emission from a z=2.3 radio galaxy

abstract:
  We present spatially resolved spectropolarimetic measurements of the 100-kpc
scale gaseous environment of the z=2.34 radio galaxy TXS 0211-122. The
polarization level of the narrow Ly-alpha emission is low centrally (P<5 %),
but rises to P=16.4+/-4.6 % in the Eastern part of the nebula, indicating that
the nebula is at least partly powered by the scattering of Ly-alpha photons by
HI. Not only is this the first detection of polarized Ly-alpha around a
radio-loud active galaxy, it is also the second detection to date for any kind
of Ly-alpha nebula. We also detect a pair of diametrically opposed UV continuum
sources along the slit, at the outer edges of the Ly-alpha nebula, which we
suggest may be the limb of a dusty shell, related to the large-scale HI
absorbers often associated with high-z radio galaxies.


title:
Voice over IP in the WiFi Network business models: Will voice be a
  killer application for WiFi Public Networks?

abstract:
  The stunning growth of WiFi networks, together with the spreading of mobile
telephony and the increasing use of Voice over IP (VoIP) on top of Internet,
pose relevant questions on the application of WiFi networks to support VoIP
services that could be used as a complement and/or competition to the 2G/3G
cellular networks. The paper explores the state of the art on the capability of
WiFi networks to support voice services in a user itinerant context,
identifying actual and future strengths, weakness, opportunities and threats.
First of all, the paper reviews the key aspects on the changing structure of
the voice market, dominated by a clear evolution to mobility, itinerancy and
increased use of VoIP-based services. The evolution of business models,
coverage for WiFi networks (hotspots, municipal networks, cooperative networks
and) and user voice service use patterns are also analysed in order to asses
the potentialities for complementing or -in some scenarios- substitute the
cellular networks.


title: Transporting microstructure and dissipative Euler flows

abstract:
  Recently the second and third author developed an iterative scheme for
obtaining rough solutions of the 3D incompressible Euler equations in H\"older
spaces (arXiv:1202.1751 and arXiv:1205.3626 (2012)). The motivation comes from
Onsager's conjecture. The construction involves a superposition of weakly
interacting perturbed Beltrami flows on infinitely many scales. An obstruction
to better regularity arises from the errors in the linear transport of a fast
periodic flow by a slow velocity field.
  In a recent paper P. Isett (arXiv:1211.4065) has improved upon our methods,
introducing some novel ideas on how to deal with this obstruction, thereby
reaching a better H\"older exponent - albeit below the one conjectured by
Onsager. In this paper we give a shorter proof of Isett's final result,
adhering more to the original scheme and introducing some new devices. More
precisely we show that for any positive $\epsilon$ there exist periodic
solutions of the 3D incompressible Euler equations which dissipate the total
kinetic energy and belong to the H\"older class $C^{\frac{1}{5}-\epsilon}$.


title:
Characterization of a Quantum Light Source Based on Spontaneous
  Parametric Down-Conversion

abstract:
  We have built a quantum light source capable of producing different types of
quantum states. The quantum light source is based on entangled state
preparation in the process of spontaneous parametric down-conversion. The
single-photon detection rate of eight-hundred thousand per second demonstrates
that we have created a bright state-of-the-art quantum light source. As a part
of the characterization we measured two-photon quantum interference in a
Hong-Ou-Mandel interferometer.


title:
Spontaneous self-ordered states of vortex-antivortex pairs in a
  Polariton Condensate

abstract:
  Polariton condensates have proved to be model systems to investigate
topological defects, as they allow for direct and non-destructive imaging of
the condensate complex order parameter. The fundamental topological excitations
of such systems are quantized vortices. In specific configurations, further
ordering can bring the formation of vortex lattices. In this work we
demonstrate the spontaneous formation of ordered vortical states, consisting in
geometrically self-arranged vortex-antivortex pairs. A mean-field generalized
Gross-Pitaevskii model reproduces and supports the physics of the observed
phenomenology.


title:
On the Complexity of Equivalence and Minimisation for Q-weighted
  Automata

abstract:
  This paper is concerned with the computational complexity of equivalence and
minimisation for automata with transition weights in the field Q of rational
numbers. We use polynomial identity testing and the Isolation Lemma to obtain
complexity bounds, focussing on the class NC of problems within P solvable in
polylogarithmic parallel time. For finite Q-weighted automata, we give a
randomised NC procedure that either outputs that two automata are equivalent or
returns a word on which they differ. We also give an NC procedure for deciding
whether a given automaton is minimal, as well as a randomised NC procedure that
minimises an automaton. We consider probabilistic automata with rewards,
similar to Markov Decision Processes. For these automata we consider two
notions of equivalence: expectation equivalence and distribution equivalence.
The former requires that two automata have the same expected reward on each
input word, while the latter requires that each input word induce the same
distribution on rewards in each automaton. For both notions we give algorithms
for deciding equivalence by reduction to equivalence of Q-weighted automata.
Finally we show that the equivalence problem for Q-weighted visibly pushdown
automata is logspace equivalent to the polynomial identity testing problem.


title:
Monoids $\mathrm{Mon}\langle
  a,b:a^{\alpha}b^{\beta}a^{\gamma}b^{\delta}a^{\varepsilon}b^{\varphi}=b\rangle$
  admit finite complete rewriting systems

abstract:
  The aim of this note is to prove that monoids $\mathrm{Mon}\langle
a,b:aUb=b\rangle$, with $aUb$ of relative length 6, admit finite complete
rewriting systems. This is some advance in the understanding the long-standing
open problem whether the word problem for one-relator monoids is soluble.


title: Linear and Geometric Mixtures - Analysis

abstract:
  Linear and geometric mixtures are two methods to combine arbitrary models in
data compression. Geometric mixtures generalize the empirically well-performing
PAQ7 mixture. Both mixture schemes rely on weight vectors, which heavily
determine their performance. Typically weight vectors are identified via Online
Gradient Descent. In this work we show that one can obtain strong code length
bounds for such a weight estimation scheme. These bounds hold for arbitrary
input sequences. For this purpose we introduce the class of nice mixtures and
analyze how Online Gradient Descent with a fixed step size combined with a nice
mixture performs. These results translate to linear and geometric mixtures,
which are nice, as we show. The results hold for PAQ7 mixtures as well, thus we
provide the first theoretical analysis of PAQ7.


title: Electron Delocalization in Gate-Tunable Gapless Silicene

abstract:
  The application of a perpendicular electric field can drive silicene into a
gapless state, characterized by two nearly fully spin-polarized Dirac cones
owing to both relatively large spin-orbital interactions and inversion symmetry
breaking. Here we argue that since inter-valley scattering from non-magnetic
impurities is highly suppressed by time reversal symmetry, the physics should
be effectively single-Dirac-cone like. Through numerical calculations, we
demonstrate that there is no significant backscattering from a single impurity
that is non-magnetic and unit-cell uniform, indicating a stable delocalized
state. This conjecture is then further confirmed from a scaling of conductance
for disordered systems using the same type of impurities.


title:
A strong open mapping theorem for surjections from cones onto Banach
  spaces

abstract:
  We show that a continuous additive positively homogeneous map from a closed
not necessarily proper cone in a Banach space onto a Banach space is an open
map precisely when it is surjective. This generalization of the usual Open
Mapping Theorem for Banach spaces is then combined with Michael's Selection
Theorem to yield the existence of a continuous bounded positively homogeneous
right inverse of such a surjective map; a strong version of the usual Open
Mapping Theorem is then a special case. As another consequence, an improved
version of the analogue of And\^o's Theorem for an ordered Banach space is
obtained for a Banach space that is, more generally than in And\^o's Theorem, a
sum of possibly uncountably many closed not necessarily proper cones.
Applications are given for a (pre)-ordered Banach space and for various spaces
of continuous functions taking values in such a Banach space or, more
generally, taking values in an arbitrary Banach space that is a finite sum of
closed not necessarily proper cones.


title: Integrating infinitesimal (super) actions

abstract:
  In this paper we generalize some results of Richard Palais to the case of Lie
supergroups and Lie superalgebras. More precisely, let $G$ be a Lie supergroup,
$\mathfrak g$ its Lie superalgebra and let $\rho$ be an infinitesimal action (a
representation) of $\mathfrak g$ on a supermanifold $M$. We will show that
there always exists a local (smooth left) action of $G$ on $M$ such that $\rho$
is the map that associates the fundamental vector field on $M$ to an algebra
element (we will say that the action integrates $\rho$). We also show that if
$\rho$ is univalent, then there exists a unique maximal local action of $G$ on
$M$ integrating $\rho$. And finally we show that if $G$ is simply connected and
all (smooth, even) vector fields $\rho(X)$ are complete then there exists a
global (smooth left) action of $G$ on $M$ integrating $\rho$. Omitting all
references to the super setting will turn our proofs into variations of those
of Palais.


title: Lingering Issues in Distributed Scheduling

abstract:
  Recent advances have resulted in queue-based algorithms for medium access
control which operate in a distributed fashion, and yet achieve the optimal
throughput performance of centralized scheduling algorithms. However,
fundamental performance bounds reveal that the "cautious" activation rules
involved in establishing throughput optimality tend to produce extremely large
delays, typically growing exponentially in 1/(1-r), with r the load of the
system, in contrast to the usual linear growth.
  Motivated by that issue, we explore to what extent more "aggressive" schemes
can improve the delay performance. Our main finding is that aggressive
activation rules induce a lingering effect, where individual nodes retain
possession of a shared resource for excessive lengths of time even while a
majority of other nodes idle. Using central limit theorem type arguments, we
prove that the idleness induced by the lingering effect may cause the delays to
grow with 1/(1-r) at a quadratic rate. To the best of our knowledge, these are
the first mathematical results illuminating the lingering effect and
quantifying the performance impact.
  In addition extensive simulation experiments are conducted to illustrate and
validate the various analytical results.


title:
The thermal dust emission in the N158-N159-N160 (LMC) star forming
  complex mapped by Spitzer, Herschel and LABOCA

abstract:
  We present a study of the infrared/submm emission of the LMC star forming
complex N158-N159-N160. Combining observations from the Spitzer Space Telescope
(3.6-70um), the Herschel Space Observatory (100-500um) and LABOCA (870um)
allows us to work at the best angular resolution available now for an
extragalactic source. We observe a remarkably good correlation between SPIRE
and LABOCA emission and resolve the low surface brightnesses emission. We use
the Spitzer and Herschel data to perform a resolved Spectral Energy
Distribution (SED) modelling of the complex. Using MBB, we derive a global
emissivity index beta_c of 1.47. If beta cold is fixed to 1.5, we find an
average temperature of 27K. We also apply the Galliano et al. (2011) modelling
technique (and amorphous carbon to model carbon dust) to derive maps of the
star formation rate, the mean starlight intensity, the fraction of PAHs or the
dust mass surface density of the region. We observe that the PAH fraction
strongly decreases in the HII regions. This decrease coincides with peaks in
the mean radiation field intensity map. The dust surface densities follow the
FIR distribution, with a total dust mass of 2.1x10^4 Msolar (2.8 times less
than when using graphite grains) in the resolved elements we model. We find a
non-negligible amount of dust in the molecular cloud N159 South (showing no
massive SF). We also investigate the drivers of the Herschel/PACS and SPIRE
submm colours as well as the variations in the gas-to-dust mass ratio (G/D) and
the XCO conversion factor in the region N159. We finally model individual
regions to analyse variations in the SED shape across the complex and the 870um
emission in more details. No measurable submm excess emission at 870um seems to
be detected in these regions.


title: Renyi entropies as a measure of the complexity of counting problems

abstract:
  Counting problems such as determining how many bit strings satisfy a given
Boolean logic formula are notoriously hard. In many cases, even getting an
approximate count is difficult. Here we propose that entanglement, a common
concept in quantum information theory, may serve as a telltale of the
difficulty of counting exactly or approximately. We quantify entanglement by
using Renyi entropies S(q), which we define by bipartitioning the logic
variables of a generic satisfiability problem. We conjecture that
S(q\rightarrow 0) provides information about the difficulty of counting
solutions exactly, while S(q>0) indicates the possibility of doing an efficient
approximate counting. We test this conjecture by employing a matrix computing
scheme to numerically solve #2SAT problems for a large number of uniformly
distributed instances. We find that all Renyi entropies scale linearly with the
number of variables in the case of the #2SAT problem; this is consistent with
the fact that neither exact nor approximate efficient algorithms are known for
this problem. However, for the negated (disjunctive) form of the problem,
S(q\rightarrow 0) scales linearly while S(q>0) tends to zero when the number of
variables is large. These results are consistent with the existence of fully
polynomial-time randomized approximate algorithms for counting solutions of
disjunctive normal forms and suggests that efficient algorithms for the
conjunctive normal form may not exist.


title:
The Properties of the Large Magellanic Cloud Based on OGLE III
  Photometry of RR Lyrae Stars

abstract:
  We present results from a study of ab-type RR Lyrae variables in the Large
Magellanic Cloud using the extensive dataset from phase III of the Optical
Gravitational Lensing Experiment (OGLE). The metallicities of the RR Lyraes,
determined from the periods and amplitudes of their light curves, reveal a
statistically significant radial abundance gradient that is approximately
one-half of what is seen in the disks of the Milky Way and M33. The RR Lyrae
abundance gradient agrees with that of the old and metal-poor LMC globular
clusters. The reddenings of the OGLE RR Lyraes have been calculated using their
minimum light colors and reveal a mean value of E(V-I) = 0.12 +/- 0.05, where
the quoted uncertainty represents the standard deviation of the mean. The
distribution of RR Lyrae extinctions across the face of the LMC is
well-correlated with the distribution and emission intensity of CO clouds based
on recent millimeter wave surveys. In addition, we find that the old LMC
globulars tend to be located in regions of low extinction. This underscores the
need to survey the higher extinction regions with the specific aim of
increasing the sample of old LMC globular clusters. Finally, we examine the
distance distribution of the RR Lyraes in order to probe the structure of the
LMC and investigate the possibility that some of the RR Lyraes may reside in a
kinematically hot halo population. In addition to calculating a mean LMC
distance of (m-M)o = 18.55 +/- 0.10 mag, we conclude that some fraction of the
RR Lyraes in our sample could be members of the LMC halo.


title:
Multi-agent RRT*: Sampling-based Cooperative Pathfinding (Extended
  Abstract)

abstract:
  Cooperative pathfinding is a problem of finding a set of non-conflicting
trajectories for a number of mobile agents. Its applications include planning
for teams of mobile robots, such as autonomous aircrafts, cars, or underwater
vehicles. The state-of-the-art algorithms for cooperative pathfinding typically
rely on some heuristic forward-search pathfinding technique, where A* is often
the algorithm of choice. Here, we propose MA-RRT*, a novel algorithm for
multi-agent path planning that builds upon a recently proposed
asymptotically-optimal sampling-based algorithm for finding single-agent
shortest path called RRT*. We experimentally evaluate the performance of the
algorithm and show that the sampling-based approach offers better scalability
than the classical forward-search approach in relatively large, but sparse
environments, which are typical in real-world applications such as
multi-aircraft collision avoidance.


title:
Existence and Construction of Resonances for Atoms Coupled to the
  Quantized Radiation Field

abstract:
  For a nonrelativistic atom, which is minimally coupled to the quantized
radiation field, resonances emerging from excited atomic eigenstates are
constructed by an iteration scheme inspired by \cite{Pizzo2003} and
\cite{BachFrohlichPizzo2006}. This scheme successively removes an infrared cut
off in momentum space and yields a convergent algorithm enabling us to
calculate the resonance eigenvalues and eigenstates, to arbitrary order in the
feinstructure constant $\alpha \sim 1/137$, and is thus an alternative method
of proof of a similar result obtained in \cite{Sigal2010}.


title: The distribution of the number of node neighbors in random hypergraphs

abstract:
  Hypergraphs, graph generalizations where edges are conglomerates of $r$ nodes
called hyperedges of rank $r\geq 2$, are excellent models to study systems with
interactions that are beyond the pairwise level. For hypergraphs, the node
degree $\ell$ (number of hyperedges connected to a node) and the number of
neighbors $k$ of a node differ from each other in contrast to the case of
graphs. Here, I calculate the distribution of the number of node neighbors in
random hypergraphs in which hyperedges of uniform rank $r$ have a homogeneous
probability $p$ to appear. This distribution is equivalent to the degree
distribution of ensembles of projected graphs from hypergraph or bipartite
network ensembles, where the projection connects any two nodes in the projected
graph when they are also connected in the hypergraph or bipartite network. The
calculation is non-trivial due to the possibility that neighbor nodes belong
simultaneously to multiple hyperedges (node overlaps). From the exact results,
the traditional sparse (small $p$) asymptotic approximation to the distribution
is rederived and improved; the approximation exhibits Poisson-like behavior
accompanied by strong fluctuations modulated by power-law decays in the system
size $N$ with decay exponents equal to the minimum number of overlapping nodes
possible for a given number of neighbors. It is shown that the dense limit
cannot be explained if overlaps are ignored, and the correct asymptotic
distribution is provided. The neighbor distribution requires the calculation of
a new combinatorial coefficient $Q_{r-1}(k,\ell)$, counting the number of
distinct labelled hypergraphs of $k$ nodes, $\ell$ hyperedges of rank $r-1$,
and where every node is connected to at least one hyperedge. Some identities of
$Q_{r-1}(k,\ell)$ are derived and applied to the verification of normalization
and the calculation of moments of the neighbor distribution.


title: Stiefel Manifolds and Coloring the Pentagon

abstract:
  We prove Csorba's conjecture that the Lov\'asz complex Hom(C_5,K_n) of graph
multimorphisms from the 5-cycle C_5 to the complete graph K_n is
Z/2Z-equivariantly homeomorphic to the Stiefel manifold, V(n-1,2), the space of
(ordered) orthonormal 2-frames in R^{n-1}. The equivariant piecewise-linear
topology that we need is developed along the way.


title: Unitary cocycles and processes on the full Fock space

abstract:
  We consider a unitary cocycle or Sch\"urmann triple on the non-commutative
unitary group fixed by a complex matrix which induces an additive free white
noise or an additive free L\'evy process on the tensor algebra over the full
Fock space. A L\'evy process on a Voiculescu dual semi-group is given by a
generator or Sch\"urmann triple. We will show how a free L\'evy process on the
non-commutative unitary group fixed by a complex matrix can be obtained by
infinitesimally convolving the additive free white noise.


title: Translocation of short and long polymers through an interacting pore

abstract:
  We perform two-dimensional Langevin dynamics simulations of electric-field
driven polymer translocation through an attractive nanopore. We investigate the
effect of the location of the attractive region using different pore patterns.
This is found to have an impact on both the translocation time as a function of
the chain length and on the polymer entry frequency. We qualitatively compare
our results to available experimental data.


title:
Comment on a recent attempt to explain the `GSI anomaly' by
  initial-state e.m. spin-rotation coupling

abstract:
  A recently proposed solution of the `GSI anomaly' by spin precession of the
decaying heavy ions in the magnetic field that controls their circular motion
at the GSI storage ring [G. Lambiase, G. Papini, G. Scarpetta, PLB 718 (2013)
998, Ann. Phys. 332 (2013) 143] is dubious: the uncertainty in the computed
electron-capture decay-rate modulation frequency is at least of order 10E(7)
Hz, by far exceeding the 1 Hz modulation frequency reported in the GSI
experiment.


title:
Non-congruence of the nuclear liquid-gas and deconfinement phase
  transitions

abstract:
  First order phase transitions (PTs) with more than one globally conserved
charge, so-called non-congruent PTs, have characteristic differences compared
to congruent PTs (e.g., dimensionality of phase diagrams, location and
properties of critical points and endpoints). In the present article we
investigate the non-congruence of the nuclear liquid-gas PT at sub-saturation
densities and the deconfinement PT at high densities and/or temperatures in
Coulomb-less models, relevant for heavy-ion collisions and neutron stars. For
the first PT, we use the FSUgold relativistic mean-field model and for the
second one the relativistic chiral SU(3) model. The chiral SU(3) model is one
of the few models for the deconfinement PT, which contains quarks and hadrons
in arbitrary proportions (i.e. a "solution") and gives a continuous transition
from pure hadronic to pure quark matter above a critical point. The study shows
the universality of the applied concept of non-congruence for the two PTs with
an upper critical point, and illustrates the different typical scales involved.
In addition, we find a principle difference between the liquid-gas and the
deconfinement PTs: in contrast to the ordinary Van-der-Waals-like PT, the phase
coexistence line of the deconfinement PT has a negative slope in the
pressure-temperature plane. As another qualitative difference we find that the
non-congruent features of the deconfinement PT become vanishingly small around
the critical point.


title: Discrete frames on finite dimensional quaternion Hilbert spaces

abstract:
  An introductory theory of frames on finite dimensional quaternion Hilbert
spaces is demonstrated along the lines of their complex counterpart.


title: Benchmarking Usability and Performance of Multicore Languages

abstract:
  Developers face a wide choice of programming languages and libraries
supporting multicore computing. Ever more diverse paradigms for expressing
parallelism and synchronization become available while their influence on
usability and performance remains largely unclear. This paper describes an
experiment comparing four markedly different approaches to parallel
programming: Chapel, Cilk, Go, and Threading Building Blocks (TBB). Each
language is used to implement sequential and parallel versions of six benchmark
programs. The implementations are then reviewed by notable experts in the
language, thereby obtaining reference versions for each language and benchmark.
The resulting pool of 96 implementations is used to compare the languages with
respect to source code size, coding time, execution time, and speedup. The
experiment uncovers strengths and weaknesses in all approaches, facilitating an
informed selection of a language under a particular set of requirements. The
expert review step furthermore highlights the importance of expert knowledge
when using modern parallel programming approaches.


title: Anomalous Surface Segregation Profiles in Ferritic FeCr Stainless Steel

abstract:
  The iron-chromium alloy and its derivatives are widely used for their
remarkable resistance to corrosion, which only occurs in a narrow concentration
range around 9 to 13 atomic percent chromium. Although known to be due to
chromium enrichment of a few atoms thick layer at the surfaces, the
understanding of its complex atomistic origin has been a remaining challenge.
We report an investigation of the thermodynamics of such surfaces at the atomic
scale by means of Monte Carlo simulations. We use a Hamiltonian which provides
a parameterization of previous ab initio results and successfully describes the
alloy's unusual thermodynamics. We report a strong enrichment in Cr of the
surfaces for low bulk concentrations, with a narrow optimum around 12 atomic
percent chromium, beyond which the surface composition decreases drastically.
This behavior is explained by a synergy between (i) the complex phase
separation in the bulk alloy, (ii) local phase transitions that tune the layers
closest to the surface to an iron-rich state and inhibit the bulk phase
separation in this region, and (iii) its compensation by a strong and
non-linear enrichment in Cr of the next few layers. Implications with respect
to the design of prospective nanomaterials are briefly discussed.


title: Mixing Strategies in Data Compression

abstract:
  We propose geometric weighting as a novel method to combine multiple models
in data compression. Our results reveal the rationale behind PAQ-weighting and
generalize it to a non-binary alphabet. Based on a similar technique we present
a new, generic linear mixture technique. All novel mixture techniques rely on
given weight vectors. We consider the problem of finding optimal weights and
show that the weight optimization leads to a strictly convex (and thus,
good-natured) optimization problem. Finally, an experimental evaluation
compares the two presented mixture techniques for a binary alphabet. The
results indicate that geometric weighting is superior to linear weighting.


title: Hypergraph Automata: A Theoretical Model for Patterned Self-assembly

abstract:
  Patterned self-assembly is a process whereby coloured tiles self-assemble to
build a rectangular coloured pattern. We propose self-assembly (SA) hypergraph
automata as an automata-theoretic model for patterned self-assembly. We
investigate the computational power of SA-hypergraph automata and show that for
every recognizable picture language, there exists an SA-hypergraph automaton
that accepts this language. Conversely, we prove that for any restricted
SA-hypergraph automaton, there exists a Wang Tile System, a model for
recognizable picture languages, that accepts the same language. The advantage
of SA-hypergraph automata over Wang automata, acceptors for the class of
recognizable picture languages, is that they do not rely on an a priori defined
scanning strategy


title:
Materials design from non-equilibrium steady states: driven graphene as
  a tunable semiconductor with topological properties

abstract:
  Controlling the properties of materials by driving them out of equilibrium is
an exciting prospect that has only recently begun to be explored. In this paper
we give a striking theoretical example of such materials design: a tunable gap
in monolayer graphene is generated by exciting a particular optical phonon. We
show that the system reaches a steady state whose transport properties are the
same as if the system had a static electronic gap, controllable by the driving
amplitude. Moreover, the steady state displays topological phenomena: there are
chiral edge currents, which circulate a fractional charge e/2 per rotation
cycle, with frequency set by the optical phonon frequency.


title: Conjugacy of Coxeter elements

abstract:
  For a Coxeter group (W,S), a permutation of the set S is called a Coxeter
word and the group element represented by the product is called a Coxeter
element. Moving the first letter to the end of the word is called a rotation
and two Coxeter elements are rotation equivalent if their words can be
transformed into each other through a sequence of rotations and legal
commutations.
  We prove that Coxeter elements are conjugate if and only if they are rotation
equivalent. This was known for some special cases but not for Coxeter groups in
general.


title: Accreting millisecond X-ray pulsars: 10 years of INTEGRAL observations

abstract:
  During the last 10 years, INTEGRAL made a unique contribution to the study of
accreting millisecond X-ray pulsars (AMXPs), discovering three of the 14
sources now known of this class. Besides increasing the number of known AMXPs,
INTEGRAL also carried out observations of these objects above 20 keV,
substantially advancing our understanding of their behaviour. We present here a
review of all the AMXPs observed with INTEGRAL and discuss the physical
interpretation of their behaviour in the X-ray domain. We focus in particular
on the lightcurve profile during outburst, as well as the timing, spectral, and
thermonuclear type-I X-ray bursts properties.


title: Submm-bright QSOs at z~2: signposts of co-evolution at high z

abstract:
  We have assembled a sample of 5 X-ray and submm-luminous z~2 QSOs which are
therefore both growing their central black holes through accretion and forming
stars copiously at a critical epoch. Hence, they are good laboratories to
investigate the co-evolution of star formation and AGN. We have performed a
preliminary analysis of the AGN and SF contributions to their UV-to-FIR SEDs,
fitting them with simple direct (disk), reprocessed (torus) and star formation
components. All three are required by the data and hence we confirm that these
objects are undergoing strong star formation in their host galaxies at rates
500-2000 Msun/y. Estimates of their covering factors are between about 30 and
90%. In the future, we will assess the dependence of these results on the
particular models used for the components and relate their observed properties
to the intrinsice of the central engine and the SF material, as well as their
relevance for AGN-galaxy coevolution.


title: Antiferromagnetic Domain Structure in Bilayer Manganite

abstract:
  We report a novel soft x-ray nanodiffraction study of antiferromagnetic
domains in the strongly correlated bylayer manganite
La$_{0.96}$Sr$_{2.04}$Mn$_{2}$O$_{7}$. We find that the antiferromagnetic
domains are quenched, forming a unique domain pattern with each domain having
an intrinsic memory of its spin direction, and with associated domain walls
running along crystallographic directions. This can be explained by the
presence of crystallographic or magnetic imperfections locked in during the
crystal growth process which pin the antiferromagnetic domains. The
antiferromagnetic domain pattern shows two distinct types of domain. We
observe, in one type only, a periodic ripple in the manganese spin direction
with a period of approximately 4 \micro\meter. We propose that the loss of
inversion symmetry within a bilayer is responsible for this ripple structure
through a Dzyaloshinskii-Moriya-type interaction.


title:
Spin(7)-instantons, stable bundles and the Bogomolov inequality for
  complex 4-tori

abstract:
  Using gauge theory for Spin(7)-manifolds of dimension 8, we develop a
procedure, called Spin-rotation, which transforms a (stable) holomorphic
structure on a vector bundle over a complex torus of dimension 4 into a new
holomorphic structure over a different complex torus. We show non-trivial
examples of this procedure by rotating a decomposable Weil abelian variety into
a non-decomposable one. As a byproduct, we obtain a Bogomolov type inequality,
which gives restrictions for the existence of stable bundles on an abelian
variety of dimension 4, and show examples in which this is stronger than the
usual Bogomolov inequality.


title: On the fractional damped oscillators and fractional forced oscillators

abstract:
  In this paper, we use the fractional calculus to discuss the fractional
mechanics, where the time derivative is replaced with the fractional derivative
of order $\nu$. We deal with the motion of a body in a resisting medium where
the retarding force is assumed to be proportional to the fractional velocity
which is obtained by acting the fractional derivative on the position. The
fractional harmonic oscillator problem, fractional damped oscillator problem
and fractional forced oscillator problem are also studied.


title: Molecular Density Functional Theory of Water

abstract:
  Three dimensional implementations of liquid state theories offer an efficient
alternative to computer simulations for the atomic-level description of aqueous
solutions in complex environments. In this context, we present a (classical)
molecular density functional theory (MDFT) of water that is derived from first
principles and is based on two classical density fields, a scalar one, the
particle density, and a vectorial one, the multipolar polarization density. Its
implementation requires as input the partial charge distribution of a water
molecule and three measurable bulk properties, namely the structure factor and
the k-dependent longitudinal and transverse dielectric constants. It has to be
complemented by a solute-solvent three-body term that reinforces tetrahedral
order at short range. The approach is shown to provide the correct
three-dimensional microscopic solvation profile around various molecular
solutes, possibly possessing H-bonding sites, at a computer cost two-three
orders of magnitude lower than with explicit simulations.


title: Disappearance and emergence of space and time in quantum gravity

abstract:
  We discuss the hints for the disappearance of continuum space and time at
microscopic scale. These include arguments for a discrete nature of them or for
a fundamental non-locality, in a quantum theory of gravity. We discuss how
these ideas are realized in specific quantum gravity approaches. Turning then
the problem around, we consider the emergence of continuum space and time from
the collective behaviour of discrete, pre-geometric atoms of quantum space, and
for understanding spacetime as a kind of "condensate", and we present the case
for this emergence process being the result of a phase transition, dubbed
"geometrogenesis". We discuss some conceptual issues of this scenario and of
the idea of emergent spacetime in general. As a concrete example, we outline
the GFT framework for quantum gravity, and illustrate a tentative procedure for
the emergence of spacetime in this framework. Last, we re-examine the
conceptual issues raised by the emergent spacetime scenario in light of this
concrete example.


title: The universal path integral

abstract:
  Path integrals represent a powerful route to quantization: they calculate
probabilities by summing over classical configurations of variables such as
fields, assigning each configuration a phase equal to the action of that
configuration. This paper defines a universal path integral, which sums over
all computable structures. This path integral contains as sub-integrals all
possible computable path integrals, including those of field theory, the
standard model of elementary particles, discrete models of quantum gravity,
string theory, etc. The universal path integral possesses a well-defined
measure that guarantees its finiteness, together with a method for extracting
probabilities for observable quantities. The universal path integral supports a
quantum theory of the universe in which the world that we see around us arises
out of the interference between all computable structures.


title: Percolation on uniform infinite planar maps

abstract:
  We construct the uniform infinite planar map (UIPM), obtained as the n \to
\infty local limit of planar maps with n edges, chosen uniformly at random. We
then describe how the UIPM can be sampled using a "peeling" process, in a
similar way as for uniform triangulations. This process allows us to prove that
for bond and site percolation on the UIPM, the percolation thresholds are
p_c^bond=1/2 and p_c^site=2/3 respectively. This method also works for other
classes of random infinite planar maps, and we show in particular that for bond
percolation on the uniform infinite planar quadrangulation, the percolation
threshold is p_c^bond=1/3.


title:
Readout of superconducting nanowire single-photon detectors at high
  count rates

abstract:
  Superconducting nanowire single-photon detectors are set apart from other
photon counting technologies above all else by their extremely high speed, with
few-ten-ps timing resolution, and recovery times $\tau_R\lesssim$10 ns after a
detection event. In this work, however, we identify in the conventional
electrical readout scheme a nonlinear interaction between the detector and its
readout which can make stable, high-efficiency operation impossible at count
rates even an order-of-magnitude less than $\tau_R^{-1}$. We present detailed
experimental confirmation of this, and a theoretical model which quantitatively
explains our observations. Finally, we describe an improved readout which
circumvents this problem, allowing these detectors to be operated stably at
high count rates, with a detection efficiency penalty determined purely by
their inductive reset time.


title:
Complexifier Versus Factorization and Deformation Methods For Generation
  of Coherent States of a 1D NLHO: I. Mathematical Construction

abstract:
  Three methods: complexifier, factorization and deformation, for construction
of coherent states are presented for one dimensional nonlinear harmonic
oscillator (1D NLHO). Since by exploring the Jacobi polynomials $P_n^{a,b}$'s,
bridging the difference between them is possible, we give here also the exact
solution of Schr\"odinger equation of 1D NLHO in terms of Jacobi polynomials.


title:
A Scaler-Based Data Acquisition System for Measuring Parity-Violating
  Asymmetry in Deep Inelastic Scattering

abstract:
  An experiment that measured the parity-violating asymmetries in deep
inelastic scattering was completed at the Thomas Jefferson National Accelerator
Facility in experimental Hall A. From these asymmetries, a combination of the
quark weak axial charge could be extracted with a factor of five improvement in
precision over world data. To achieve this, asymmetries at the $10^{-4}$ level
needed to be measured at event rates up to 600 kHz and the high pion background
typical to deep inelastic scattering experiments needed to be rejected
efficiently. A specialized data acquisition (DAQ) system with intrinsic
particle identification (PID) was successfully developed and used: The pion
contamination in the electron samples was controlled at the order of $2\times
10^{-4}$ or below with an electron efficiency of higher than 91 % during most
of the production period of the experiment, the systematic uncertainty in the
measured asymmetry due to DAQ deadtime was below 0.5 %, and the statistical
quality of the asymmetry measurement agreed with the Gaussian distribution to
over five orders of magnitudes. The DAQ system is presented here with an
emphasis on its design scheme, the achieved PID performance, deadtime effect
and the capability of measuring small asymmetries.


title: Polar-Coded Modulaton

abstract:
  A framework is proposed that allows for a joint description and optimization
of both binary polar coding and $2^m$-ary digital pulse-amplitude modulation
(PAM) schemes such as multilevel coding (MLC) and bit-interleaved coded
modulation (BICM). The conceptual equivalence of polar coding and multilevel
coding is pointed out in detail. Based on a novel characterization of the
channel polarization phenomenon, rules for the optimal choice of the labeling
in coded modulation schemes employing polar codes are developed. Simulation
results regarding the error performance of the proposed schemes on the AWGN
channel are included.


title:
Combining non-stationary prediction, optimization and mixing for data
  compression

abstract:
  In this paper an approach to modelling nonstationary binary sequences, i.e.,
predicting the probability of upcoming symbols, is presented. After studying
the prediction model we evaluate its performance in two non-artificial test
cases. First the model is compared to the Laplace and Krichevsky-Trofimov
estimators. Secondly a statistical ensemble model for compressing
Burrows-Wheeler-Transform output is worked out and evaluated. A systematic
approach to the parameter optimization of an individual model and the ensemble
model is stated.


title: From Hypercomplex to Holomorphic Symplectic Structures

abstract:
  The notions of holomorphic symplectic structures and hypercomplex structures
on Courant algebroids are introduced and then proved to be equivalent. These
generalize hypercomplex triples and holomorphic symplectic 2-forms on manifolds
respectively. Basic properties of such structures are established.


title:
Micro-alloying and the Toughness of Glasses: Modeling with Pinned
  Particles

abstract:
  The usefulness of glasses, and particularly of metallic glasses, in
technological applications is often limited by their toughness, which is
defined as the area under the stress vs. strain curve before plastic yielding.
Recently toughness was found to increase significantly by the addition of small
concentrations of foreign atoms that act as pinning centers. We model this
phenomenon at zero temperature and quasi-static straining with randomly
positioned particles that participate in the elastic deformation but are pinned
in the non-affine return to mechanical equilibrium. We find a very strong
effect on toughness via the increase of both the shear modulus and the yield
stress as a function of the density of pinned particles. Understanding the
results calls for analyzing separately the elastic, or "Born term" and the
contributions of the "excess modes" that result from glassy disorder. Finally
we present a scaling theory that collapses the data on one universal curve as a
function of rescaled variables.


title: Negative Energy Seen By Accelerated Observers

abstract:
  The sampled negative energy density seen by inertial observers, in arbitrary
quantum states is limited by quantum inequalities, which take the form of an
inverse relation between the magnitude and duration of the negative energy. The
quantum inequalities severely limit the utilization of negative energy to
produce gross macroscopic effects, such as violations of the second law of
thermodynamics. The restrictions on the sampled energy density along the
worldlines of accelerated observers are much weaker than for inertial
observers. Here we will illustrate this with several explicit examples. We
consider the worldline of a particle undergoing sinusoidal motion in space in
the presence of a single mode squeezed vacuum state of the electromagnetic
field. We show that it is possible for the integrated energy density along such
a worldline to become arbitrarily negative at a constant average rate. Thus the
averaged weak energy condition is violated in these examples.This can be the
case even when the particle moves at non-relativistic speeds. We use the
Raychaudhuri equation to show that there can be net defocussing of a congruence
of these accelerated worldlines. This defocussing is an operational signature
of the negative integrated energy density. These results in no way invalidate
nor undermine either the validity or utility of the quantum inequalities for
inertial observers. In particular, they do not change previous constraints on
the production of macroscopic effects with negative energy, e.g., the
maintenance of traversable wormholes.


title:
Temporal variations of X-ray solar flare loops: length, corpulence,
  position, temperature, plasma pressure and spectra

abstract:
  The spatial and spectral properties of three solar flare coronal X-ray loops
are studied before, during and after the peak X-ray emission. Using
observations from the Ramaty High Energy Solar Spectroscopic Imager (RHESSI),
we deduce the temporal changes in emitting X-ray length, corpulence, volume,
position, number density and thermal pressure. We observe a decrease in the
loop length, width and volume before the X-ray peak, and an increasing number
density and thermal pressure. After the X-ray peak, volume increases and loop
corpulence grows due to an increasing width. The volume variations are more
pronounced than the position variations, often known as magnetic line
contraction. We believe this is the first dedicated study of the temporal
evolution of X-ray loop lengths and widths. Collectively, the observations also
show for the first time three temporal phases given by peaks in temperature,
X-ray emission and thermal pressure, with minimum volume coinciding with the
X-ray peak. Although the volume of the flaring plasma decreases before the peak
in X-ray emission, the relationship between temperature and volume does not
support simple compressive heating in a collapsing magnetic trap model. Within
a low beta plasma, shrinking loop widths perpendicular to the guiding field can
be explained by squeezing the magnetic field threading the region. Plasma
heating leads to chromospheric evaporation and growing number density,
producing increasing thermal pressure and decreasing loop lengths as electrons
interact at shorter distances and we believe after the X-ray peak, the
increasing loop corpulence.


title: The evolution of the AGN content in groups up to z~1

abstract:
  Determining the AGN content in structures of different mass/velocity
dispersion and comparing them to higher mass/lower redshift analogs is
important to understand how the AGN formation process is related to
environmental properties. We use our well-tested cluster finding algorithm to
identify structures in the GOODS North and South fields, exploiting the
available spectroscopic redshifts and accurate photometric redshifts. We
identify 9 structures in GOODS-south (presented in a previous paper) and 8 new
structures in GOODS-north. We only consider structures where at least 2/3 of
the members brighter than M_R=-20 have a spectroscopic redshift. For those
group members that coincide with X-ray sources in the 4 and 2 Msec Chandra
source catalogs respectively, we determine if the X-ray emission originates
from AGN activity or it is related to the galaxies' star-formation activity. We
find that the fraction of AGN with Log L_H > 42 erg/s in galaxies with M_R <
-20 is on average 6.3+-1.3%, much higher than in lower redshift groups of
similar mass and more than double the fraction found in massive clusters at a
similarly high redshift. We then explore the spatial distribution of AGN in the
structures and find that they preferentially populate the outer regions. The
colors of AGN host galaxies in structures tend to be confined to the green
valley, thus avoiding the blue cloud and, partially, also the red-sequence,
contrary to what happens in the field. We finally compare our results to the
predictions of two sets of semi analytic models to investigate the evolution of
AGN and evaluate potential triggering and fueling mechanisms. The outcome of
this comparison attests the importance of galaxy encounters, not necessarily
leading to mergers, as an efficient AGN triggering mechanism. (abridged)


title: Local solution method for the problem of enlargement of filtration

abstract:
  The enlargement of filtration theory is a study of semimartingales when the
basic filtration changes. This theory provides particular techniques on
stochastic calculus. We present here a technique, that we call the local
solution method. We will show, with several examples, that the local solution
method is an effective and flexible method. In particular, with the local
solution method, we will give a unified proof of three of the classical
formulas, namely Jacod's formula, the progressive enlargement formula and the
enlargement formula with honest time. We also show that, besides its
generality, this method, necessiting long (but interesting) computations, may
not be optimal.


title: Interactive Methods of Teaching Physics at Technical Universities

abstract:
  The papeer presents results of "non-traditional" teaching of basic course of
Physics in the first year of study at the Technical University in Zvolen,
specifically teaching via interactive method based on an increased focus on
problem tasks and experiments. This paper presents also research results of the
use of the given method in conditions of Slovak universities and its
comparision with traditional methods.


title: Prompt charm production in pp collisions at sqrt(s)=7 TeV

abstract:
  Charm production at the LHC in pp collisions at sqrt(s)=7 TeV is studied with
the LHCb detector. The decays D0 -> K- pi+, D+ -> K- pi+ pi+, D*+ -> D0(K- pi+)
pi+, D_s+ -> phi(K- K+) pi+, Lambda_c+ -> p K- pi+, and their charge conjugates
are analysed in a data set corresponding to an integrated luminosity of 15
nb^{-1}. Differential cross-sections dsigma/dp_T are measured for prompt
production of the five charmed hadron species in bins of transverse momentum
and rapidity in the region 0 < p_T < 8 GeV/c and 2.0 < y < 4.5. Theoretical
predictions are compared to the measured differential cross-sections. The
integrated cross-sections of the charm hadrons are computed in the above p_T-y
range, and their ratios are reported. A combination of the five integrated
cross-section measurements gives
  sigma(c\bar{c})_{p_T < 8 GeV/c, 2.0 < y < 4.5} = 1419 +/- 12 (stat) +/- 116
(syst) +/- 65 (frag) microbarn,
  where the uncertainties are statistical, systematic, and due to the
fragmentation functions.


title:
Singularity of eigenfunctions at the junction of shrinking tubes, Part
  II

abstract:
  In continuation with the paper arXiv:1202.4414, we investigate the asymptotic
behavior of weighted eigenfunctions in two half-spaces connected by a thin
tube. We provide several improvements about some convergences stated in
arXiv:1202.4414; most of all, we provide the exact asymptotic behavior of the
implicit normalization for solutions given in arXiv:1202.4414 and thus describe
the (N-1)-order singularity developed at a junction of the tube (where N is the
space dimension).


title: Analytically solvable model of an electronic Mach-Zehnder interferometer

abstract:
  We consider a class of models of non-equilibrium electronic Mach-Zehnder
interferometers built on integer quantum Hall edges states. The models are
characterized by the electron-electron interaction being restricted to the
inner part of the interferometer and transmission coefficients of the quantum
quantum point contacts, defining the interferometer, which may take arbitrary
values from zero to one. We establish an exact solution of these models in
terms of single-particle quantities --- determinants and resolvents of Fredholm
integral operators. In the general situation, the results can be obtained
numerically. In the case of strong charging interaction, the operators acquire
the block Toeplitz form. Analyzing the corresponding Riemann-Hilbert problem,
we reduce the result to certain singular single-channel determinants (which are
a generalization of Toeplitz determinants with Fisher-Hartwig singularities),
and obtain an analytic result for the interference current (and, in particular,
for the visibility of Aharonov-Bohm oscillations). Our results, which are in
good agreement with experimental observations, show an intimate connection
between the observed "lobe" structure in the visibility of Aharonov-Bohm
oscillations and multiple branches in the asymptotics of singular integral
determinants.


title: The true stellar parameters of the Kepler target list

abstract:
  Using population synthesis tools we create a synthetic Kepler Input Catalogue
(KIC) and subject it to the Kepler Stellar Classification Program (SCP) method
for determining stellar parameters such as the effective temperature Teff and
surface gravity g. We achieve a satisfactory match between the synthetic KIC
and the real KIC in the log g vs log Teff diagram, while there is a significant
difference between the actual physical stellar parameters and those derived by
the SCP of the stars in the synthetic sample. We find a median difference
\Delta Teff=+500K and \Delta log g =-0.2dex for main-sequence stars, and \Delta
Teff=+50K and \Delta log g =-0.5dex for giants, although there is a large
variation across parameter space. For a MS star the median difference in g
would equate to a ~3% increase in stellar radius and a consequent ~3%
overestimate of the radius for any transiting exoplanet. We find no significant
difference between \Delta Teff and \Delta log g for single stars and the
primary star in a binary system. We also re-created the Kepler target selection
method and found that the binary fraction is unchanged by the target selection.
Binaries are selected in similar proportions to single star systems; the
fraction of MS dwarfs in the sample increases from about 75% to 80%, and the
giant star fraction decreases from 25% to 20%.


title:
The Kitaev-Ising model, Transition between topological and ferromagnetic
  order

abstract:
  We study the Kitaev-Ising model, where ferromagnetic Ising interactions are
added to the Kitaev model on a lattice. This model has two phases which are
characterized by topological and ferromagnetic order. Transitions between these
two kinds of order are then studied on a quasi-one dimensional system, a
ladder, and on a two dimensional periodic lattice, a torus. By exactly mapping
the quasi-one dimensional case to an anisotropic XY chain we show that the
transition occurs at zero $\lambda$ where $\lambda$ is the strength of the
ferromagnetic coupling. In the two dimensional case the model is mapped to a 2D
Ising model in transverse field, where it shows a transition at finite value of
$\lambda$. A mean field treatment reveals the qualitative character of the
transition and an approximate value for the transition point. Furthermore with
perturbative calculation, we show that expectation value of Wilson loops behave
as expected in the topological and ferromagnetic phases.


title: Searching and Bargaining with Middlemen

abstract:
  We study decentralized markets with the presence of middlemen, modeled by a
non-cooperative bargaining game in trading networks. Our goal is to investigate
how the network structure of the market and the role of middlemen influence the
market's efficiency and fairness. We introduce the concept of limit stationary
equilibrium in a general trading network and use it to analyze how competition
among middlemen is influenced by the network structure, how endogenous delay
emerges in trade and how surplus is shared between producers and consumers.


title:
Design for a fountain of YbF molecules to measure the electron's
  electric dipole moment

abstract:
  We propose an experiment to measure the electric dipole moment of the
electron using ultracold YbF molecules. The molecules are produced as a thermal
beam by a cryogenic buffer gas source, and brought to rest in an optical
molasses that cools them to the Doppler limit or below. The molecular cloud is
then thrown upward to form a fountain in which the electric dipole moment of
the electron is measured.


title:
Second sound and the superfluid fraction in a resonantly interacting
  Fermi gas

abstract:
  Superfluidity is a macroscopic quantum phenomenon, which shows up below a
critical temperature and leads to a peculiar behavior of matter, with
frictionless flow, the formation of quantized vortices, and the quenching of
the moment of inertia being intriguing examples. A remarkable explanation for
many phenomena exhibited by a superfluid at finite temperature can be given in
terms of a two-fluid mixture comprised of a normal component that behaves like
a usual fluid and a superfluid component with zero viscosity and zero entropy.
Important examples of superfluid systems are liquid helium and neutron stars.
More recently, ultracold atomic gases have emerged as new superfluid systems
with unprecedented possibilities to control interactions and external
confinement. Here we report the first observation of `second sound' in an
ultracold Fermi gas with resonant interactions. Second sound is a striking
manifestation of the two-component nature of a superfluid and corresponds to an
entropy wave, where the superfluid and the non-superfluid components oscillate
in opposite phase, different from ordinary sound (`first sound'), where they
oscillate in phase. The speed of second sound depends explicitly on the value
of the superfluid fraction, a quantity sensitive to the spectrum of elementary
excitations. Our measurements allow us to extract the temperature dependence of
the superfluid fraction, which in strongly interacting quantum gases has been
an inaccessible quantity so far.


title: Chiral three-nucleon force at N^4LO II: Intermediate-range contributions

abstract:
  We derive the subleading contributions to the two-pion-one-pion exchange and
ring three-nucleon force topologies emerging at
next-to-next-to-next-to-next-to-leading order in chiral effective field theory.
The resulting expressions do not involve any unknown parameters. To study
convergence of the chiral expansion we work out the most general operator
structure of a local isospin-invariant three-nucleon force. Using the resulting
operator basis with 22 independent structures, we compare the strength of the
corresponding potentials in configuration space for individual topologies at
various orders in the chiral expansion. As expected, the subleading
contributions from the two-pion-one-pion-exchange and ring diagrams are large
which can be understood in terms of intermediate excitation of the Delta(1232)
isobar.


title:
Existence and Solution-representation of IVP for LFDE with Generalized
  Riemann-Liouville fractional derivatives and $n$ terms

abstract:
  This paper provides the existence and representation of solution to an
initial value problem for the general multi-term linear fractional differential
equation with generalized Riemann-Liouville fractional derivatives and constant
coefficients by using operational calculus of Mikusinski's type. We prove that
the initial value problem has the solution of if and only if some initial
values should be zero.


title: Star formation in Galactic spiral arms and the inter-arm regions

abstract:
  The line of sight through the Galactic Plane between longitudes l = 37.83
degr and l = 42.50 degr allows for the separation of Galactic Ring Survey
molecular clouds into those that fall within the spiral arms and those located
in the inter-arm regions. By matching these clouds in both position and
velocity with dense clumps detected in the mm continuum by the Bolocam Galactic
Plane Survey, we are able to look for changes in the clump formation efficiency
(CFE), the ratio of clump-to-cloud mass, with Galactic environment. We find no
evidence of any difference in the CFE between the inter-arm and spiral-arm
regions along this line of sight. This is further evidence that, outside the
Galactic Centre region, the large-scale structures of the Galaxy play little
part in changing the dense, potentially star-forming structures within
molecular clouds.


title:
Information Transmission using the Nonlinear Fourier Transform, Part
  III: Spectrum Modulation

abstract:
  Motivated by the looming "capacity crunch" in fiber-optic networks,
information transmission over such systems is revisited. Among numerous
distortions, inter-channel interference in multiuser wavelength-division
multiplexing (WDM) is identified as the seemingly intractable factor limiting
the achievable rate at high launch power. However, this distortion and similar
ones arising from nonlinearity are primarily due to the use of methods suited
for linear systems, namely WDM and linear pulse-train transmission, for the
nonlinear optical channel. Exploiting the integrability of the nonlinear
Schr\"odinger (NLS) equation, a nonlinear frequency-division multiplexing
(NFDM) scheme is presented, which directly modulates non-interacting signal
degrees-of-freedom under NLS propagation. The main distinction between this and
previous methods is that NFDM is able to cope with the nonlinearity, and thus,
as the the signal power or transmission distance is increased, the new method
does not suffer from the deterministic cross-talk between signal components
which has degraded the performance of previous approaches. In this paper,
emphasis is placed on modulation of the discrete component of the nonlinear
Fourier transform of the signal and some simple examples of achievable spectral
efficiencies are provided.


title:
The classification of totally umbilical surfaces in homogeneous
  3-manifolds

abstract:
  We obtain an exhaustive classification of totally umbilical surfaces in
unimodular and non-unimodular simply-connected 3-dimensional Lie groups endowed
with arbitrary left-invariant Riemannian metrics. This completes the
classification of totally umbilical surfaces in homogeneous Riemannian
3-manifolds.


title: Granular Brownian Motors: role of gas anisotropy and inelasticity

abstract:
  We investigate the motion of a wedge-shaped object (a granular Brownian
motor), which is restricted to move along the x-axis and cannot rotate, as gas
particles collide with it. We show that its steady-state drift, resulting from
inelastic gas-motor collisions, is dramatically affected by anisotropy in the
velocity distribution of the gas. We identify the dimensionless parameter
providing the dependence of this drift on shape, masses, inelasticity, and
anisotropy: the anisotropy leads to a dramatic breaking of equipartition, which
should easily be visible in experimental realizations.


title:
Can car density in a two-lane section depend on the position of the
  latter in a single-lane road?

abstract:
  We report here results on the study of the totally asymmetric simple
exclusion processes (TASEP), defined on an open network, consisting of head and
tail simple chain segments with a double-chain section inserted in-between.
Results of numerical simulations for relatively short chains reveal an
interesting new feature of the network. When the current through the system
takes its maximum value, a simple translation of the double-chain section
forward or backward along the network, leads to a sharp change in the shape of
the density profiles in the parallel chains, thus affecting the total number of
cars in that part of the network. In the symmetric case of equal injection and
ejection rates (\alpha = \beta >1/2) and equal lengths of the head and tail
sections, the density profiles in the two parallel chains are almost linear,
characteristic for the coexistence line (shock phase). Upon moving the section
forward (backward), their shape changes to the one typical for the high (low)
density phases of a simple chain. The total bulk density of cars in a section
with a large number of parallel chains is evaluated too. The observed effect
might have interesting implications for the traffic flow control as well as for
biological transport processes in living cells. An explanation of this
phenomenon is offered in terms of finite-size dependence of the effective
injection and ejection rates at the ends of the double-chain section.


title:
A Comparison of Far IR and HI as Reddening Predictors at High Galactic
  Latitude

abstract:
  Both the Galactic 21-cm line flux from neutral hydrogen (HI) in interstellar
medium and the far-infrared (FIR) emission from Galactic dust grains have been
used to estimate the strength of Galactic reddening of distant sources. In this
work we use a collection of uniform color distant galaxies as color standards
to determine whether the HI method or the FIR method is superior. We find that
the two methods both produce reasonably accurate maps, but that both show
significant errors as compared to the typical color of the background galaxies.
We find that a mixture of the FIR and HI maps in roughly a 2-to-1 ratio is
clearly superior to either map alone. We recommend that future reddening maps
should use both sets of data, and that well-constructed FIR and HI maps should
both be vigorously pursued.