title:
Inverse of magnetic dipole field using a reversible jump Markov chain
  Monte Carlo

abstract:
  We consider a three-dimensional magnetic field produced by an arbitrary
collection of dipoles. Assuming the magnetic vector or its gradient tensor
field is measured above the earth surface, the inverse problem is to use the
measurement data to find the location, strength, orientation and distribution
of the dipoles underneath the surface. We propose a reversible jump Markov
chain Monte Carlo (RJ-MCMC) algorithm for both the magnetic vector and its
gradient tensor to deal with this trans-dimensional inverse problem where the
number of unknowns is one of the unknowns. A special birth-death move strategy
is designed to obtain a reasonable rate of acceptance for the RJ-MCMC sampling.
  Some preliminary results show the strength and challenges of the algorithm in
inverting the magnetic measurement data through dipoles. Starting with an
arbitrary single dipole, the algorithm automatically produces a cloud of
dipoles to reproduce the observed magnetic field, and the true dipole
distribution for a bulky object is better predicted than for a thin object.
Multi-objects located at different depths remain a very challenging inverse
problem.


title: Term-ordering free involutive bases

abstract:
  In this paper, we consider a monomial ideal J in P := A[x1,...,xn], over a
commutative ring A, and we face the problem of the characterization for the
family Mf(J) of all homogeneous ideals I in P such that the A-module P/I is
free with basis given by the set of terms in the Groebner escalier N(J) of J.
This family is in general wider than that of the ideals having J as initial
ideal w.r.t. any term-ordering, hence more suited to a computational approach
to the study of Hilbert schemes. For this purpose, we exploit and enhance the
concepts of multiplicative variables, complete sets and involutive bases
introduced by Janet and we generalize the construction of J-marked bases and
term-ordering free reduction process introduced and deeply studied for the
special case of a strongly stable monomial ideal J. Here, we introduce and
characterize for every monomial ideal J a particular complete set of generators
F(J), called stably complete, that allows an explicit description of the family
Mf(J). We obtain stronger results if J is quasi stable, proving that F(J) is a
Pommaret basis and Mf(J) has a natural structure of affine scheme. The final
section presents a detailed analysis of the origin and the historical evolution
of the main notions we refer to.


title: On the Optical Role of Randomness for Structured Surfaces

abstract:
  It has been known for years how random height variations of a repeated
nano-scale structure can give rise to smooth angular color variations instead
of the well-known diffraction pattern experienced if no randomization is
present. However, until now there has not been published any papers giving an
in-depth mathematical explanation on the mechanisms behind and how to design
the randomness for a given application. This paper presents a mathematical
framework for analyzing these random variations -- rigorously as well as
intuitively.


title: Quasi-periodic oscillations from Rossby Wave Instability

abstract:
  We study the Rossby wave instability model of high-frequency quasi-periodic
oscillations (QPO) of microquasars. We show ray-traced light curves of QPO
within this model and discuss perspectives of distinguishing alternative QPO
models with the future Large Observatory For X-ray Timing (LOFT) observations.


title:
On the Parameterized Complexity of Associative and Commutative
  Unification

abstract:
  This paper studies the unification problem with associative, commutative, and
associative-commutative functions mainly from a viewpoint of the parameterized
complexity on the number of variables. It is shown that both associative and
associative-commutative unification problems are $W[1]$-hard. A fixed-parameter
algorithm and a polynomial-time algorithm are presented for special cases of
commutative unification in which one input term is variable-free and the number
of variables is bounded by a constant, respectively. Related results including
those on the string and tree edit distance problems with variables are shown
too.


title: On Invariants and Endomorphism Rings of Local Cohomology Modules

abstract:
  Let $(R,\mathfrak{m})$ denote an $n$-dimensional Gorenstein ring. For an
ideal $I \subset R$ with $\grade I = c$ we define new numerical invariants
$\tau_{i,j}(I)$ as the socle dimensions of $H^i_{\mathfrak{m}}(H^{n-j}_I(R))$.
In case of a regular local ring containing a field these numbers coincide with
the Lyubeznik numbers $\lambda_{i,j}(R/I)$. We use $\tau_{d,d}(I), d = \dim
R/I,$ to characterize the surjectivity of the natural homomorphism $f : \hat{R}
\to \Hom_{\hat{R}}(H^c_{I\hat{R}}(\hat{R}),H^c_{I\hat{R}}(\hat{R}))$. As a
technical tool we study several natural homomorphisms. Moreover we prove a few
results on $\tau_{i,j}(I)$.


title:
Enantioselectivity of (321) chiral noble metal surfaces: A Density
  Functional Theory study of lactate adsorption

abstract:
  The adsorption of the chiral molecule lactate on the intrinsically chiral
noble metal surfaces Pt(321), Au(321) and Ag(321) is studied by Density
Functional Theory calculations. We use the oPBE-vdW functional which includes
van der Waals forces on an ab initio level. It is shown that the molecule binds
via its carboxyl and the hydroxyl oxygen atoms to the surface. The binding
energy is larger on Pt(321) and Ag(321) than on Au(321). An analysis of the
contributions to the binding energy of the different molecular functional
groups reveals that the deprotonated carboxyl group contributes most to the
binding energy, with a much smaller contribution of the hydroxyl group. The
Pt(321) surface shows considerable enantioselectivity of 0.06 eV. On Au(321)
and Ag(321) it is much smaller if not vanishing. The chiral selectivity of the
Pt(321) surface can be explained by two factors. First, it derives from the
difference in van der Waals attraction of L- and D-lactate to the surface that
we trace to differences in the binding energy of the methyl group. Second, the
multi-point binding pattern for lactate on the Pt(321) surface is sterically
more sensitive to surface chirality and also leads to large binding energy
contributions of the hydroxyl group. We also calculate the charge transfer to
the molecule and the work function to gauge changes in electronic structure of
the adsorbed molecule. The work function is lowered by 0.8 eV on Pt(321) with
much smaller changes on Au(321) and Ag(321).


title:
Beam steering and topological transformations driven by interactions
  between discrete vortex and fundamental solitons

abstract:
  We study coherent and incoherent interactions between discrete vortex and
fundamental solitons in two-dimensional photonic lattices, presenting a new
scheme for all-optical routings and topological transformations of vorticities.
Due to the multi-lobe intensity and step-phase structure of the discrete vortex
soliton, the coherent soliton-interactions allow both solitons to be steered
into multiple different possible destination ports depending on the initial
phase of the discrete fundamental soliton. We show that charge-flipping of
phase singularities and orbital angular momentum transfer can occur during the
coherent interactions between the two solitons. For incoherent interactions, by
controlling the relative intensities of the two solitons, we reveal that
soliton-steering can be realized by either attracting the discrete fundamental
soliton to four ports or localizing the four-lobe discrete vortex soliton into
a ring soliton.


title:
Controlling the Spontaneous Emission Rate of Monolayer MoS$_2$ in a
  Photonic Crystal Nanocavity

abstract:
  We report on controlling the spontaneous emission (SE) rate of a molybdenum
disulfide (MoS$_2$) monolayer coupled with a planar photonic crystal (PPC)
nanocavity. Spatially resolved photoluminescence (PL) mapping shows strong
variations of emission when the MoS$_2$ monolayer is on the PPC cavity, on the
PPC lattice, on the air gap, and on the unpatterned gallium phosphide
substrate. Polarization dependences of the cavity-coupled MoS$_2$ emission show
a more than 5 times stronger extracted PL intensity than the un-coupled
emission, which indicates an underlying cavity mode Purcell enhancement of
MoS$_2$ SE rate exceeding a factor of 70.


title: The empirical cost of optimal incomplete transportation

abstract:
  We consider the problem of optimal incomplete transportation between the
empirical measure on an i.i.d. uniform sample on the d-dimensional unit cube
$[0,1]^d$ and the true measure. This is a family of problems lying in between
classical optimal transportation and nearest neighbor problems. We show that
the empirical cost of optimal incomplete transportation vanishes at rate
$O_P(n^{-1/d})$, where n denotes the sample size. In dimension $d\geq3$ the
rate is the same as in classical optimal transportation, but in low dimension
it is (much) higher than the classical rate.


title: The Shock and the Turbulence: the story of an interaction

abstract:
  Video highlighting multiple features of the interaction between isotropic
turbulence and a nominally planar shock wave, normal to the mean flow
direction. The visualizations showcased in this video were obtained from a
Direct Numerical Simulation.


title: Simulating non-Markovian stochastic processes

abstract:
  We present a simple and general framework to simulate statistically correct
realizations of a system of non-Markovian discrete stochastic processes. We
give the exact analytical solution and a practical an efficient algorithm alike
the Gillespie algorithm for Markovian processes, with the difference that now
the occurrence rates of the events depend on the time elapsed since the event
last took place. We use our non-Markovian generalized Gillespie stochastic
simulation methodology to investigate the effects of non-exponential
inter-event time distributions in the susceptible-infected-susceptible model of
epidemic spreading. Strikingly, our results unveil the drastic effects that
very subtle differences in the modeling of non-Markovian processes have on the
global behavior of complex systems, with important implications for their
understanding and prediction. We also assess our generalized Gillespie
algorithm on a system of biochemical reactions with time delays. As compared to
other existing methods, we find that the generalized Gillespie algorithm is the
most general as it can be implemented very easily in cases, like for delays
coupled to the evolution of the system, where other algorithms do not work or
need adapted versions, less efficient in computational terms.


title: Learning Chordal Markov Networks by Constraint Satisfaction

abstract:
  We investigate the problem of learning the structure of a Markov network from
data. It is shown that the structure of such networks can be described in terms
of constraints which enables the use of existing solver technology with
optimization capabilities to compute optimal networks starting from initial
scores computed from the data. To achieve efficient encodings, we develop a
novel characterization of Markov network structure using a balancing condition
on the separators between cliques forming the network. The resulting
translations into propositional satisfiability and its extensions such as
maximum satisfiability, satisfiability modulo theories, and answer set
programming, enable us to prove optimal certain network structures which have
been previously found by stochastic search.


title: Problems of determination of \sigma_{tot} at the LHC

abstract:
  The analysis of the procedure of the determining the parameters of the hadron
elastic scattering amplitude at high energy is presented. The exponential and
non-exponential form of the scattering amplitude are taken into account.
Especially, the impact of the real parts of the hadron scattering amplitude and
electromagnetic hadron interaction on the determination of the total cross
section is examined.


title: Quantifying entanglement with scattering experiments

abstract:
  We show how the entanglement contained in states of spins arranged on a
lattice may be quantified with observables arising in scattering experiments.
We focus on the partial differential cross-section obtained in neutron
scattering from magnetic materials but our results are sufficiently general
such that they may also be applied to, e.g., optical Bragg scattering from
ultracold atoms in optical lattices or from ion chains. We discuss resonating
valence bond states and ground and thermal states of experimentally relevant
models--such as Heisenberg, Majumdar-Ghosh, and XY model--in different
geometries and with different spin numbers. As a by-product, we find that for
the one-dimensional XY model in a transverse field such measurements reveal
factorization and the quantum phase transition at zero temperature.


title:
Exploiting multi-scale parallelism for large scale numerical modelling
  of laser wakefield accelerators

abstract:
  A new generation of laser wakefield accelerators, supported by the extreme
accelerating fields generated in the interaction of PW-Class lasers and
underdense targets, promises the production of high quality electron beams in
short distances for multiple applications. Achieving this goal will rely
heavily on numerical modeling for further understanding of the underlying
physics and identification of optimal regimes, but large scale modeling of
these scenarios is computationally heavy and requires efficient use of
state-of-the-art Petascale supercomputing systems. We discuss the main
difficulties involved in running these simulations and the new developments
implemented in the OSIRIS framework to address these issues, ranging from
multi-dimensional dynamic load balancing and hybrid distributed / shared memory
parallelism to the vectorization of the PIC algorithm. We present the results
of the OASCR Joule Metric program on the issue of large scale modeling of LWFA,
demonstrating speedups of over 1 order of magnitude on the same hardware.
Finally, scalability to over $\sim 10^6$ cores, and sustained performance over
$\sim 2$ PFlops is demonstrated, opening the way for large scale modeling of
laser wakefield accelerator scenarios.


title: Constraining the two-Higgs doublet models with the LHC data

abstract:
  The recent discovery of a Standard Model-like boson with mass of about 126
GeV seems to be the first direct information on the electroweak symmetry
breaking mechanism. Using the available experimental data from the LHC and
Tevatron we study the implications on the parameter space of the Two-Higgs
Doublet Model extension of the Standard Model. The generic structure of the
Aligned Two-Higgs Doublet model is imposed in the Yukawa sector; also the
models with discrete $\mathcal{Z}_2$ symmetries are analyzed.


title:
Event-triggered transmission for linear control over communication
  channels

abstract:
  We consider an exponentially stable closed loop interconnection of a
continuous linear plant and a continuous linear controller, and we study the
problem of interconnecting the plant output to the controller input through a
digital channel. We propose a family of "transmission-lazy" sensors whose goal
is to transmit the measured plant output information as little as possible
while preserving closed-loop stability. In particular, we propose two
transmission policies, providing conditions on the transmission parameters.
These guarantee global asymptotic stability when the plant state is available
or when an estimate of the state is available (provided by a classical
continuous linear observer). Moreover, under a specific condition, they
guarantee global exponential stability


title: Logspace computations for Garside groups of spindle type

abstract:
  M. Picantin introduced the notion of Garside groups of spindle type,
generalizing the 3-strand braid group. We show that, for linear Garside groups
of spindle type, a normal form and a solution to the conjugacy problem are
logspace computable. For linear Garside groups of spindle type with homogenous
presentation we compute a geodesic normal form in logspace.


title:
Raman scattering as a probe of charge nematic fluctuations in iron based
  superconductors

abstract:
  We report Raman scattering measurement of charge nematic fluctuations in the
tetragonal phase of BaFe$_2$As$_2$ and Sr(Fe$_{1-x}$Co$_x$)$_2$As$_2$ (x=0.04)
single crystals. In both systems, the observed nematic fluctuations are found
to exhibit divergent Curie-Weiss like behavior with very similar characteristic
temperature scales, indicating a universal tendency towards charge nematic
order in 122 iron-based superconductors.


title:
Mapping electronic reconstruction at the metal/insulator interfaces in
  \ce{LaVO_3/SrVO_3} heterostructures

abstract:
  A \ce{(LaVO_3)_6/(SrVO_3)_3} superlattice is studied with a combination of
sub-{\AA} resolved scanning transmission electron microscopy and monochromated
electron energy-loss spectroscopy. The V oxidation state is mapped with atomic
spatial resolution enabling to investigate electronic reconstruction at the
\ce{LaVO_3}/\ce{SrVO_3} interfaces. Surprisingly, asymmetric charge
distribution is found at adjacent chemically symmetric interfaces. The local
structure is proposed and simulated with double channeling calculation which
agrees qualitatively with our experiment. We demonstrate that local strain
asymmetry is the likely cause of the electronic asymmetry of the interfaces.
The electronic reconstruction at the interfaces extends much further than the
chemical composition, varying from 0.5 to 1.2 nm. This distance corresponds to
the length of charge transfer previously found in the
\ce{(LaVO_3)_m}/\ce{(SrVO_3)_n} metal/insulating and the
\ce{(LaAlO_3)_m}/\ce{(SrTiO_3)_n} insulating/insulating interfaces.


title: Double Centralizers of Parabolic Subgroups of Braid Groups

abstract:
  We characterize the double centralizer of all parabolic subgroups of the
braid groups. We apply this result to provide a new and potentially more
efficient solution to the subgroup conjugacy problem for parabolic subgroups.
In the course of the proof we also characterize the centralizer for all
parabolic subgroups.


title: Two-loop part of the rational homotopy of spaces of long embeddings

abstract:
  Arone and Turchin defined graph-complexes computing the rational homotopy of
the spaces of long embeddings. The graph-complexes split into a direct sum by
the number of loops in graphs. In this paper we compute the homology of its
two-loop part.


title: On the Significance of the Gottesman-Knill Theorem

abstract:
  According to the Gottesman-Knill theorem, quantum algorithms which utilise
only the operations belonging to a certain restricted set are efficiently
simulable classically. Since some of the operations in this set generate
entangled states, it is commonly concluded that entanglement is insufficient to
enable quantum computers to outperform classical computers. I argue in this
paper that this conclusion is misleading. First, the statement of the theorem
(that the particular set of quantum operations in question can be simulated
using a classical computer) is, on reflection, already evident when we consider
Bell's and related inequalities in the context of a discussion of computational
machines. This, in turn, helps us to understand that the appropriate conclusion
to draw from the Gottesman-Knill theorem is not that entanglement is
insufficient to enable a quantum performance advantage, but rather that if we
limit ourselves to the operations referred to in the Gottesman-Knill theorem,
we will not have used the resources provided by an entangled quantum system to
their full potential.


title: Optimal transportation under controlled stochastic dynamics

abstract:
  We consider an extension of the Monge-Kantorovitch optimal transportation
problem. The mass is transported along a continuous semimartingale, and the
cost of transportation depends on the drift and the diffusion coefficients of
the continuous semimartingale. The optimal transportation problem minimizes the
cost among all continuous semimartingales with given initial and terminal
distributions. Our first main result is an extension of the Kantorovitch
duality to this context. We also suggest a finite-difference scheme combined
with the gradient projection algorithm to approximate the dual value. We prove
the convergence of the scheme, and we derive a rate of convergence. We finally
provide an application in the context of financial mathematics, which
originally motivated our extension of the Monge-Kantorovitch problem. Namely,
we implement our scheme to approximate no-arbitrage bounds on the prices of
exotic options given the implied volatility curve of some maturity.


title: Quasi-phase-matching of only even-order high harmonics

abstract:
  We propose a method for generating only even-order high harmonics. We
formulate a condition for a shift in the relative-phase between bi-chromatic
drivers that leads to a field sign-flip of only even-order harmonics. Induction
of this sign-flip periodically during propagation gives rise to quasi phase
matching of only even harmonics. We demonstrate this technique numerically and
also show that it leads to attosecond pulse trains with constant carrier
envelop phase with high repetition rate. This work opens the door for
quasi-phase matching of high harmonics with a designed selective enhancement
function.


title:
$B$ Meson Decay Constants $f_{B_c}$, $f_{B_s}$ and $f_B$ from QCD Sum
  Rules

abstract:
  Finite energy QCD sum rules with Legendre polynomial integration kernels are
used to determine the heavy meson decay constant $f_{B_c}$, and revisit $f_B$
and $f_{B_s}$. Results exhibit excellent stability in a wide range of values of
the integration radius in the complex squared energy plane, and of the order of
the Legendre polynomial. Results are $f_{B_c} = 528 \pm 19$ MeV, $f_B = 186 \pm
14$ MeV, and $f_{B_s} = 222 \pm 12$ MeV.


title:
Proper and improper zero energy modes in Hartree-Fock theory and their
  relevance for symmetry breaking and restoration

abstract:
  We study the spectra of the molecular orbital Hessian (stability matrix) and
random-phase approximation Hamiltonian of broken-symmetry Hartree-Fock
solutions, focusing on zero eigenvalue modes. After all negative eigenvalues
are removed from the Hessian by following their eigenvectors downhill, one is
left with only positive and zero eigenvalues. Zero modes correspond to orbital
rotations with no restoring force. These rotations determine states in the
Goldstone manifold, which originates from a spontaneously broken continuous
symmetry in the wave function. Zero modes can be classified as improper or
proper according to their different mathematical and physical properties.
Improper modes arise from symmetry breaking and their restoration always lowers
the energy. Proper modes, on the other hand, correspond to degeneracies of the
wave function, and their symmetry restoration does not necessarily lower the
energy. We discuss how the RPA Hamiltonian distinguishes between proper and
improper modes by doubling the number of zero eigenvalues associated with the
latter. Proper modes in the Hessian always appear in pairs which do not double
in RPA. We present several pedagogical cases exemplifying the above statements.
The relevance of these results for projected Hartree-Fock methods is also
addressed.


title:
Wind and Wave Extremes over the World Oceans From Very Large Forecast
  Ensembles

abstract:
  Global return value estimates of significant wave height and 10-m neutral
wind speed are estimated from very large aggregations of archived ECMWF
ensemble forecasts at +240-h lead time from the period 2003-2012. The upper
percentiles are found to match ENVISAT wind speed better than ERA-Interim
(ERA-I), which tends to be biased low. The return estimates are significantly
higher for both wind speed and wave height in the extratropics and the
subtropics than what is found from ERA-I, but lower than what is reported by
Caires and Sterl (2005) and Vinoth and Young (2011). The highest discrepancies
between ERA-I and ENS240 are found in the hurricane-prone areas, suggesting
that the ensemble comes closer than ERA-I in capturing the intensity of
tropical cyclones. The width of the confidence intervals are typically reduced
by 70% due to the size of the data sets. Finally, non-parametric estimates of
return values were computed from the tail of the distribution. These direct
return estimates compare very well with Generalized Pareto estimates.


title: Self-affine sets with non-compactly supported random perturbations

abstract:
  In this note we consider the Hausdorff dimension of self-affine sets with
random perturbations. We extend previous work in this area by allowing the
random perturbation to be distributed according to distributions with unbounded
support as long as the measure of the tails of the distribution decay super
polynomially.


title: The Tuning System for the HIE-ISOLDE High-Beta Quarter Wave Resonator

abstract:
  A new linac using superconducting quarter-wave resonators (QWR) is under
construction at CERN in the framework of the HIE-ISOLDE project. The QWRs are
made of niobium sputtered on a bulk copper substrate. The working frequency at
4.5 K is 101.28 MHz and they will provide 6 MV/m accelerating gradient on the
beam axis with a total maximum power dissipation of 10 W on cavity walls. A
tuning system is required in order to both minimize the forward power variation
in beam operation and to compensate the unavoidable uncertainties in the
frequency shift during the cool-down process. The tuning system has to fulfil a
complex combination of RF, structural and thermal requirements. The paper
presents the functional specifications and details the tuning system RF and
mechanical design and simulations. The results of the tests performed on a
prototype system are discussed and the industrialization strategy is presented
in view of final production.


title:
Next-to-leading order QCD corrections to $HW^{\pm}\gamma$ production at
  the LHC

abstract:
  The Higgs boson production associated with a $W$-boson and a photon at the
Large Hadron Collider (LHC) can be used to probe the coupling between Higgs
boson and vector gauge bosons and discover a signature of new physics. We
present the precision predictions up to the QCD next-to-leading-order (NLO) in
the standard model for this process involving the subsequential weak decays of
the final Higgs and $W$-boson. The dependence of the leading order (LO) and the
QCD NLO corrected integrated cross sections on the
factorization/renormalization energy scale is studied. We provide the LO and
QCD NLO corrected distributions of the transverse momenta and rapidities of
final products. We find that the LO cross section is significantly enhanced by
the QCD NLO correction, and the $K$-factor value is obviously related to the
physical observables and the phase space regions.


title: Inequalities via n-times differentiable convex functions

abstract:
  In this paper, we establish some integral ineuqalities for n- times
differentiable convex functions.


title:
Possible detection of a cyclotron resonance scattering feature in the
  X-ray pulsar 4U 1909+07

abstract:
  We present timing and broad-band spectral studies of the high mass X-ray
binary pulsar 4U 1909+07 using data from Suzaku observation during 2010
November 2-3. The pulse period of the pulsar is estimated to be 604.11+/-0.14
s. Pulsations are seen in the X-ray light curve up to ~70 keV. The pulse
profile is found to be strongly energy-dependent: a complex, multi-peaked
structure at low energy that becomes a simple single peak at higher energy. We
found that the 1-70 keV pulse averaged continuum can be fitted by the sum of a
black body and a partial covering Negative and Positive power-law with
EXponential cutoff (NPEX) model. A weak iron fluorescence emission line at 6.4
keV was detected in the spectrum. An absorption like feature at ~44 keV was
clearly seen in the residue of the spectral fitting, independent of the
continuum model adopted. To check the possible presence of a CRSF in the
spectrum, we normalized the pulsar spectrum with the spectrum of the Crab
Nebula. The resulting Crab ratio also showed a clear dip centered at ~44 keV.
We performed statistical tests on the residue of the spectral fitting and also
on the Crab spectral ratio to determine the significance of the absorption like
feature and identified it as a CRSF of the pulsar. We estimated the
corresponding surface magnetic field of the pulsar to be 3.8 x 10^12 Gauss.


title:
Rapid Dust Formation in Novae: The Speed Class - Formation Timescale
  Correlation Explained

abstract:
  Observations show that the time of onset of dust formation in classical novae
depends strongly on their speed class, with dust typically taking longer to
form in slower novae. Using empirical relationships between speed class,
luminosity and ejection velocity, it can be shown that dust formation timescale
is expected to be essentially independent of speed class. However, following a
nova outburst the spectrum of the central hot source evolves, with an
increasing proportion of the radiation being emitted short-ward of the Lyman
limit. The rate at which the spectrum evolves also depends on the speed class.
We have therefore refined the simple model by assuming photons at energies
higher than the Lyman limit are absorbed by neutral hydrogen gas internal to
the dust formation sites, therefore preventing these photons reaching the
nucleation sites. With this refinement the dust formation timescale is
theoretically dependent on speed class and the results of our theoretical
modification agree well with the observational data. We consider two types of
carbon-based dust, graphite and amorphous carbon, with both types producing
similar relationships. Our results can be used to predict when dust will form
in a nova of a given speed class and hence when observations should optimally
be taken to detect the onset of dust formation.


title: Analytic Model of Doubly Commuting Contractions

abstract:
  An n-tuple (n \geq 2), T = (T_1, \ldots, T_n), of commuting bounded linear
operators on a Hilbert space \mathcal{H} is doubly commuting if T_i T_j^* =
T_j^* T_i for all $1 \leq i < j \leq n$. If in addition, each T_i \in C_{\cdot
0}, then we say that T is a doubly commuting pure tuple. In this paper we prove
that a doubly commuting pure tuple $T$ can be dilated to a tuple of shift
operators on some suitable vector-valued Hardy space
H^2_{\mathcal{D}_{T^*}}(\mathbb{D}^n). As a consequence of the dilation
theorem, we prove that there exists a closed subspace \mathcal{S}_T of the form
\[\mathcal{H}_{T} := \sum_{i=1}^n \Phi_{T_i}
H^2_{\mathcal{E}_{T_i}}(\mathbb{D}^n),\] where \{\mathcal{E}_{T_i}\}_{i=1}^n
are Hilbert spaces, \Phi_{T_i} \in H^\infty_{\mathcal{B}(\mathcal{E}_{T_i},
\mathcal{D}_{T^*})}(\mathbb{D}^n) such that each \Phi_{T_i} (1 \leq i \leq n)
is either a one variable inner function in z_i, or the zero function. Moreover,
\mathcal{H} \cong \mathcal{S}_T^\perp and \[(T_1, \ldots, T_n) \cong
P_{\mathcal{S}_T^\perp} (M_{z_1}, \ldots, M_{z_n})|_{\mathcal{S}_T^\perp}.\]


title:
Fractional Laplacians on domains, a development of H\"ormander's theory
  of mu-transmission pseudodifferential operators

abstract:
  Let $P$ be a classical pseudodifferential operator of complex order $m$ on an
$n$-dimensional smooth manifold $\Omega_1$. For the truncation $P_\Omega$ to a
smooth subset $\Omega$ there is a well-known theory of boundary value problems
when $P_\Omega$ has the transmission property (preserves $C^\infty
(\bar\Omega)$) and is of integer order; the calculus of Boutet de Monvel. Many
interesting operators, such as for example complex powers of the Laplacian
$(-\Delta)^\mu $ with noninteger mu, are not covered. They have instead the
mu-transmission property defined in H\"ormander's books, mapping $x_n^\mu
C^\infty (\bar\Omega)$ into $C^\infty (\bar\Omega)$. In an unpublished lecture
note from 1965, H\"ormander described an $L_2$-solvability theory for
mu-transmission operators, departing from Vishik and Eskin's results. We here
develop the theory in $L_p$ Sobolev spaces ($1<p<\infty$) in a modern setting.
It leads to not only Fredholm solvability statements but also regularity
results in full scales of Sobolev spaces (for $s\to \infty$). The solution
spaces have a singularity at the boundary that we describe in detail. We
moreover obtain results in H\"older spaces, which radically improve recent
regularity results for fractional Laplacians.


title: Relative subanalytic sheaves

abstract:
  Given a projection $f$ of a product of real analytic manifolds onto one
factor, let us say, $S$, and a subanalytic sheaf $\mathcal{F}$ on the
associated subanalytic site, we give a natural construction of the
(subanalytic) relative sheaf $\mathcal{F}^S$. Applying our construction to the
subanalytic sheaves of tempered distributions, holomorphic functions and
Whitney $\mathcal{C}^{\infty}$-functions we obtain their relative versions and
study their properties.


title: On the Muskat problem: global in time results in 2D and 3D

abstract:
  This paper considers the three dimensional Muskat problem in the stable
regime. We obtain a conservation law which provides an $L^2$ maximum principle
for the fluid interface. We also show global in time existence for strong and
weak solutions with initial data controlled by explicit constants. Furthermore
we refine the estimates from our paper \cite{PDPB} to obtain global existence
and uniqueness for strong solutions with larger initial data than we previously
had in 2D. Finally we provide global in time results in critical spaces, giving
solutions with bounded slope and time integrable bounded curvature.


title:
The Physics of the $\theta$-angle for Composite Extensions of the
  Standard Model

abstract:
  We analyse the $\theta$-angle physics associated to extensions of the
standard model of particle interactions featuring new strongly coupled sectors.
We start by providing a pedagogical review of the $\theta$-angle physics for
Quantum Chromodynamics (QCD) including also the axion properties. We then move
to analyse composite extensions of the standard model elucidating the interplay
between the new $\theta$-angle with the QCD one. We consider first QCD-like
dynamics and then generalise it to consider several kinds of new strongly
coupled gauge theories with fermions transforming according to different matter
representations. Our analysis is of immediate use for different models of
composite Higgs dynamics, composite dark matter and inflation.


title:
Bijective Mappings Of Meshes With Boundary And The Degree In Mesh
  Processing

abstract:
  This paper introduces three sets of sufficient conditions, for generating
bijective simplicial mappings of manifold meshes. A necessary condition for a
simplicial mapping of a mesh to be injective is that it either maintains the
orientation of all elements or flips all the elements. However, these
conditions are known to be insufficient for injectivity of a simplicial map. In
this paper we provide additional simple conditions that, together with the
above mentioned necessary conditions guarantee injectivity of the simplicial
map.
  The first set of conditions generalizes classical global inversion theorems
to the mesh (piecewise-linear) case. That is, proves that in case the boundary
simplicial map is bijective and the necessary condition holds then the map is
injective and onto the target domain. The second set of conditions is concerned
with mapping of a mesh to a polytope and replaces the (often hard) requirement
of a bijective boundary map with a collection of linear constraints and
guarantees that the resulting map is injective over the interior of the mesh
and onto. These linear conditions provide a practical tool for optimizing a map
of the mesh onto a given polytope while allowing the boundary map to adjust
freely and keeping the injectivity property in the interior of the mesh. The
third set of conditions adds to the second set the requirement that the
boundary maps are orientation preserving as-well (with a proper definition of
boundary map orientation). This set of conditions guarantees that the map is
injective on the boundary of the mesh as-well as its interior. Several
experiments using the sufficient conditions are shown for mapping triangular
meshes.
  A secondary goal of this paper is to advocate and develop the tool of degree
in the context of mesh processing.


title:
A multi-level preconditioned Krylov method for the efficient solution of
  algebraic tomographic reconstruction problems

abstract:
  Classical iterative methods for tomographic reconstruction include the class
of Algebraic Reconstruction Techniques (ART). Convergence of these stationary
linear iterative methods is however notably slow. In this paper we propose the
use of Krylov solvers for tomographic linear inversion problems. These advanced
iterative methods feature fast convergence at the expense of a higher
computational cost per iteration, causing them to be generally uncompetitive
without the inclusion of a suitable preconditioner. Combining elements from
standard multigrid (MG) solvers and the theory of wavelets, a novel
wavelet-based multi-level (WMG) preconditioner is introduced, which is shown to
significantly speed-up Krylov convergence. The performance of the
WMG-preconditioned Krylov method is analyzed through a spectral analysis, and
the approach is compared to existing methods like the classical Simultaneous
Iterative Reconstruction Technique (SIRT) and unpreconditioned Krylov methods
on a 2D tomographic benchmark problem. Numerical experiments are promising,
showing the method to be competitive with the classical Algebraic
Reconstruction Techniques in terms of convergence speed and overall performance
(CPU time) as well as precision of the reconstruction.


title: Conformal Extensions of the Standard Model with Veltman Conditions

abstract:
  Using the renormalisation group framework we classify different extensions of
the standard model according to their degree of naturality. A new relevant
class of perturbative models involving elementary scalars is the one in which
the theory simultaneously satisfies the Veltman conditions and is conformal at
the classical level. We term these extensions perturbative natural conformal
(PNC) theories. We show that PNC models are very constrained and thus highly
predictive. Among the several PNC examples that we exhibit, we discover a
remarkably simple PNC extension of the standard model in which the Higgs is
predicted to have the experimental value of the mass equal to 126 GeV. This
model also predicts the existence of one more standard model singlet scalar
boson with a mass of 541 GeV and the Higgs self-coupling to emerge radiatively.
We study several other PNC examples that generally predict a somewhat smaller
mass of the Higgs to the perturbative order we have investigated them. Our
results can be a useful guide when building extensions of the standard model
featuring fundamental scalars.


title:
Effect of nonlinear dissipation on the basin boundaries of a driven
  two-well Modified Rayleigh-Duffing Oscillator

abstract:
  This paper considers effect of nonlinear dissipation on the basin boundaries
of a driven two-well Modified Rayleigh-Duffing Oscillator where pure and unpure
quadratic and cubic nonlinearities are considered. By analyzing the potential,
an analytic expression is found for the homoclinic orbit. The Melnikov
criterion is used to examine a global homoclinic bifurcation and transition to
chaos in the case of our oscillator. It is found the effects of unpure
quadratic parameter and amplitude of parametric excitation on the critical
Melnikov amplitude $\mu_{cr}$. Finally, we examine carefully the phase space of
initial conditions in order to analyze the effect of the nonlinear damping, and
particular how the basin boundaries become fractalized.


title: Non abelian cohomology of extensions of Lie algebras as Deligne groupoid

abstract:
  In this note we show that the theory of non abelian extensions of a Lie
algebra $\mathfrak{g}$ by a Lie algebra $\mathfrak{h}$ can be understood in
terms of a differential graded Lie algebra $L$. More precisely we show that the
non-abelian cohomology $H^2_{nab}(\mathfrak{g},\mathfrak{h})$ is
$\mathcal{MC}(L)$, the $\pi_0$ of the Deligne groupoid of $L$.


title: Intermediate model between Majority voter PCA and its Mean Field model

abstract:
  Probabilistic Cellular Automata (PCA) are simple models used to study
dynamical phase transitions. There exist mean field approximations to PCA that
can be shown to exhibit a phase transition. We introduce a model interpolating
between a class of PCA, called majority voters, and their corresponding mean
field models. Using graphical methods, we prove that this model undergoes a
phase transition.


title: Effects of non-uniform Mn distribution in (Ga,Mn)As

abstract:
  Resonant in situ photoemission from Mn 3d states in Ga_{1-x}Mn_{x}As is
reported for Mn concentrations down to very dilute limit of 0.1 at %. The
properties of the peak at the valence-band maximum reveal an effective
interaction between Mn 3d states for concentration as low as 2.5 %.
Concentration-dependent spectral features are analyzed on the basis of
first-principles calculations for systems with selected impurity positions as
well as for random alloys.


title: Stellar Magnetism and starspots: the implications for exoplanets

abstract:
  Stellar variability induce by starspots can hamper the detection of
exoplanets and bias planet property estimations. These features can also be
used to study star-planet interactions as well as inferring properties from the
underlying stellar dynamo. However, typical techniques, such as ZDI, are not
possible for most host-stars. We present a robust method based on spot
modelling to map the surface of active star allowing us to statistically study
the effects and interactions of stellar magnetism with transiting exoplanets.
The method is applied to the active Kepler-9 star where we find small evidence
for a possible interaction between planet and stellar magnetosphere which leads
to a 2:1 resonance between the spot rotation and orbital period.


title: Gluonic observables and the scalar spectrum of twelve-flavour QCD

abstract:
  We measure glueball masses and the string tension in twelve-flavour QCD,
aiming at comparing the emerging gluonic spectrum to the mesonic one. When
approaching the critical surface at zero quark mass, the hierarchy of masses in
the different sectors of the spectrum gives a new handle to determine the
existence of an infrared fixed point. We describe the details of our gluonic
measurements and the results obtained on a large number of gauge configurations
generated with the HISQ action. In particular, we focus on the scalar glueball
and its mixing with a flavour-singlet fermionic state, which is lighter than
the pseudoscalar (would-be pion) state. The results are interesting in view of
a light composite Higgs boson in walking technicolor theories.


title:
Quantum correlations in the 1-D driven dissipative transverse field XY
  model

abstract:
  We study the non-equilibrium steady state (NESS) of a driven dissipative
one-dimensional system near a critical point, and explore how the quantum
correlations compare to the known critical behavior in the ground state. The
model we study corresponds to a cavity array driven parametrically at a two
photon resonance, equivalent in a rotating frame to a transverse field
anisotropic XY model [C. E. Bardyn and A. Imamo\u{g}lu, Phys. Rev. Lett {\bf
109} 253606 (2012)]. Depending on the sign of transverse field, the steady
state of the open system can be either related to the ground state or to the
maximum energy state. In both cases, many properties of the entanglement are
similar to the ground state, although no critical behavior occurs. As one
varies from the Ising limit to the isotropic XY limit, entanglement range
grows. The isotropic limit of the NESS is however singular, with simultaneously
diverging range and vanishing magnitude of entanglement. This singular limiting
behavior is quite distinct from the ground state behavior, it can however be
understood analytically within spin-wave theory.


title:
Non-isothermal viscous Cahn--Hilliard equation with inertial term and
  dynamic boundary conditions

abstract:
  We consider a non-isothermal modified Cahn--Hilliard equation which was
previously analyzed by M. Grasselli et al. Such an equation is characterized by
an inertial term and a viscous term and it is coupled with a hyperbolic heat
equation. The resulting system was studied in the case of no-flux boundary
conditions. Here we analyze the case in which the order parameter is subject to
a dynamic boundary condition. This assumption requires a more refined strategy
to extend the previous results to the present case. More precisely, we first
prove the well-posedness for solutions with bounded energy as well as for weak
solutions. Then we establish the existence of a global attractor. Finally, we
prove the convergence of any given weak solution to a single equilibrium by
using a suitable Lojasiewicz--Simon inequality.


title: Complete analysis for three-qubit mixed-state discrimination

abstract:
  In this article, by treating minimum error state discrimination as a
complementarity problem, we obtain the geometric optimality conditions. These
can be used as the necessary and sufficient conditions to determine whether
every optimal measurement operator can be nonzero. Using these conditions and
an inductive approach, we demonstrate a geometric method and the intrinsic
polytope for N-qubit mixed-state discrimination. When the intrinsic polytope
becomes a point, a line segment, or a triangle, the guessing probability, the
necessary and sufficient condition for the exact solution, and the optimal
measurement are analytically obtained. We apply this result to the problem of
discrimination to arbitrary three-qubit mixed states with given a priori
probabilities and obtain the complete analytic solution to the guessing
probability and optimal measurement.


title: The SAT-UNSAT transition in the adversarial SAT problem

abstract:
  Adversarial SAT (AdSAT) is a generalization of the satisfiability (SAT)
problem in which two players try to make a boolean formula true (resp. false)
by controlling their respective sets of variables. AdSAT belongs to a higher
complexity class in the polynomial hierarchy than SAT and therefore the nature
of the critical region and the transition are not easily paralleled to those of
SAT and worth of independent study. AdSAT also provides an upper bound for the
transition threshold of the quantum satisfiability problem (QSAT). We present a
complete algorithm for AdSAT, show that 2-AdSAT is in $\mathbf{P}$, and then
study two stochastic algorithms (simulated annealing and its improved variant)
and compare their performances in detail for 3-AdSAT. Varying the density of
clauses $\alpha$ we find a sharp SAT-UNSAT transition at a critical value whose
upper bound is $\alpha_c \lesssim 1.5$, thus providing a much stricter upper
bound for the QSAT transition than those previously found.

categories: cs.CC cond-mat.dis-nn cond-mat.stat-mech cs.AI cs.LO


title:
Inclusive Deep Inelastic Scattering at High Q2 with Longitudinally
  Polarised Lepton Beams at HERA

abstract:
  Inclusive e^\pm p single and double differential cross sections for neutral
(NC) and charged current (CC) deep inelastic scattering processes are measured
with the H1 detector at HERA. The data were taken at a centre-of-mass energy of
\sqrt{s} = 319 GeV with a total integrated luminosity of 327.8 pb^{-1} shared
between two lepton beam charges and two longitudinal lepton polarisation modes.
The differential cross sections are measured in the range of negative
four-momentum transfer squared, Q2, between 60 and 50 000 GeV2, and Bjorken x
between 0.0008 and 0.65. The measurements are combined with earlier published
unpolarised H1 data to improve statistical precision and used to determine the
structure function xF_3^{\gamma Z}. A measurement of the structure function
F_2^{\gamma Z}, sensitive to parity violating effects in NC, is presented for
the first time. The polarisation dependence of the CC total cross section is
also measured. The new measurements are well described by a next-to-leading
order QCD fit based on all published H1 inclusive cross section data which are
used to extract the parton distribution functions of the proton.


title: 3D massless Kane fermions observed in a zinc-blende crystal

abstract:
  Solid state physics and quantum electrodynamics with its ultra-relativistic
(massless) particles meet, to their mutual beneit, in the electronic properties
of one-dimensional carbon nanotubes as well as two-dimensional graphene or
surfaces of topological insulators. However, clear experimental evidence for
electronic states with conical dispersion relations in all three dimensions,
conceivable in certain bulk materials, is still missing. In the present work,
we fabricate and study a zinc-blend crystal, HgCdTe, at the point of the
semiconductor-to-semimetal topological transition. Three-dimensional massless
electrons with a velocity of about 10$^6$ m/s are observed in this material, as
testifed by: (i) the dynamical conductivity which increases linearly with the
photon frequency, (ii) in a magnetic field $B$, by a $\sqrt{B}$ dependence of
dipole-active inter-Landau-level resonances and (iii) the spin splitting of
Landau levels, which follows a $\sqrt{B}$ dependence, typical of
ultra-relativistic particles but not really seen in any other electronic system
so far.


title: Photo-induced doping and strain in exfoliated graphene

abstract:
  The modification of single layer graphene due to intense, picoseconds
near-infrared laser pulses is investigated. We monitor the stable changes
introduced to graphene upon photoexcitation using Raman spectroscopy. We find
that photoexcitation leads to both a local increase in hole doping and a
reduction in compressive strain. Possible explanations for these effects, due
to photo-induced oxygenation and photo-induced buckling of the graphene, are
discussed.


title:
Thermoelectric properties of atomic-thin silicene and germanene
  nano-structures

abstract:
  The thermoelectric properties in one- and two-dimensional silicon and
germanium structures have been investigated using first-principle density
functional techniques and linear response for the thermal and electrical
transport. We have considered here the two-dimensional silicene and germanene,
together with nano-ribbons of different widths. For the nano-ribbons, we have
also investigated the possibility of nano-structuring these systems by mixing
silicon and germanium. We found that the figure of merit at room temperature of
these systems is remarkably high, up to 2.5.


title:
Strategies for an accurate determination of the X(3872) energy from QCD
  lattice simulations

abstract:
  We develop a method to determine accurately the binding energy of the X(3872)
from lattice data for the $D \bar D^*$ interaction. We show that, because of
the small difference between the neutral and charged components of the X(3872),
it is necessary to differentiate them in the energy levels of the lattice
spectrum if one wishes to have a precise determination of the the binding
energy of the X(3872). The analysis of the data requires the use of coupled
channels. Depending on the number of levels available and the size of the box
we determine the precision needed in the lattice energies to finally obtain a
desired accuracy in the binding energy.


title:
Accelerating inference for diffusions observed with measurement error
  and large sample sizes using Approximate Bayesian Computation

abstract:
  In recent years dynamical modelling has been provided with a range of
breakthrough methods to perform exact Bayesian inference. However it is often
computationally unfeasible to apply exact statistical methodologies in the
context of large datasets and complex models. This paper considers a nonlinear
stochastic differential equation model observed with correlated measurement
errors and an application to protein folding modelling. An Approximate Bayesian
Computation (ABC) MCMC algorithm is suggested to allow inference for model
parameters within reasonable time constraints. The ABC algorithm uses
simulations of "subsamples" from the assumed data generating model as well as a
so-called "early rejection" strategy to speed up computations in the ABC-MCMC
sampler. Using a considerate amount of subsamples does not seem to degrade the
quality of the inferential results for the considered applications. A
simulation study is conducted to compare our strategy with exact Bayesian
inference, the latter resulting two orders of magnitude slower than ABC-MCMC
for the considered setup. Finally the ABC algorithm is applied to a large size
protein data. The suggested methodology is fairly general and not limited to
the exemplified model and data.


title:
On Two-dimensional Hamiltonian Transport Equations with $L^p_{loc}$
  coefficients

abstract:
  We consider two-dimensional autonomous divergence free vector-fields in
$\Lde_{loc}$. Under a condition on direction of the flow and on the set of
critical points, we prove the existence and uniqueness of a stable a.e. flow
and of renormalized solutions of the associated transport equation.


title: Convergence of incremental adaptive systems

abstract:
  In this paper, incremental adaptive mechanisms are presented and
characterized, to provide design hints for the development of continuous-time
adaptive systems. The comparison with the conventional integral adaptive
systems indicates that the suggested design methodology will be a supplement to
the existing ones. With the aid of a Barbalat-like lemma, convergence results
of the incremental adaptive systems are established. It is shown that the
proposed adaptive mechanisms are able to work well in handling parametric
uncertainties in systems undertaken.


title: On Liouville transport equation with a force field in $BV_{loc}$

abstract:
  We prove the existence and uniqueness of renormalized solutions of the
Liouville equation for $n$ particles with a interaction potential in $BV_{loc}$
execpt at the origin. This implies the existence and uniqueness of a a.e. flow
solution of the associated ODE.


title:
Multivalued backward stochastic differential equations with oblique
  subgradients

abstract:
  We study the existence and uniqueness of the solution for the following
backward stochastic variational inequality with oblique reflection (for short,
$BSVI\left(H(t,y),\varphi,F\right)$), written under differential form \[
\left\{\begin{array} [c]{l}% -dY_{t}+H\left(t,Y_{t}\right)
\partial\varphi\left(Y_{t}\right) \left(dt\right) \ni
F\left(t,Y_{t},Z_{t}\right) dt-Z_{t}dB_{t},\quad t\in\left[ 0,T\right]
,\smallskip\\ Y_{T}=\eta, \end{array} \right. \] where $H$ is a bounded
symmetric smooth matrix and $\varphi$ is a proper convex lower semicontinuous
function, with $\partial\varphi$ being its subdifferential operator. The
presence of the product $H\partial\varphi$ does not permit the use of standard
techniques because it does conserve neither the Lipschitz property of the
matrix nor the monotonicity property of the subdifferential operator. We prove
that, if we consider the dependence of $H$ only on the time, the equation
admits a unique strong solution and, allowing the dependence also on the state
of the system, the above $BSVI\left(H(t,y),\varphi,F\right)$ admits a weak
solution in the sense of the Meyer-Zheng topology. However, for that purpose we
must renounce at the dependence on $Z$ for the generator function and we
situate our problem in a Markovian framework.


title: Counterion Condensation on Spheres in the Salt-free Limit

abstract:
  A highly-charged spherical colloid in a salt-free environment exerts such a
powerful attraction on its counterions that a certain fraction condenses onto
the surface of a particle. The degree of condensation depends on the curvature
of the surface. So, for instance, condensation is triggered on a highly-charged
sphere only if the radius exceeds a certain critical radius $\collrad^{*}$.
$\collrad^{*}$ is expected to be a simple function of the volume fraction of
particles. To test these predictions, we prepare spherical particles which
contain a covalently-bound ionic liquid, which is engineered to dissociate
efficiently in a low-dielectric medium. By varying the proportion of ionic
liquid to monomer we synthesise nonpolar dispersions of highly-charged spheres
which contain essentially no free co-ions. The only ions in the system are
counterions generated by the dissociation of surface-bound groups. We study the
electrophoretic mobility of this salt-free system as a function of the colloid
volume fraction, the particle radius, and the bare charge density and find
evidence for extensive counterion condensation. At low electric fields, we
observe excellent agreement with Poisson-Boltzmann predictions for counterion
condensation on spheres. At high electric fields however, where ion advection
is dominant, the electrophoretic mobility is enhanced significantly which we
attribute to hydrodynamic stripping of the condensed layer of counterions from
the surface of the particle.


title: Approximation of rational numbers by Dedekind sums

abstract:
  Given a rational number $x$ and a bound $\varepsilon$, we exhibit $m,n$ such
that $|x-12 s(m,n)|<\varepsilon$. Here $s(m,n)$ is the classical Dedekind sum
and the parameters $m$ and $n$ are completely explicit in terms of $x$ and
$\varepsilon$.


title: PLUMED 2: New feathers for an old bird

abstract:
  Enhancing sampling and analyzing simulations are central issues in molecular
simulation. Recently, we introduced PLUMED, an open-source plug-in that
provides some of the most popular molecular dynamics (MD) codes with
implementations of a variety of different enhanced sampling algorithms and
collective variables (CVs). The rapid changes in this field, in particular new
directions in enhanced sampling and dimensionality reduction together with new
hardwares, require a code that is more flexible and more efficient. We
therefore present PLUMED 2 here - a complete rewrite of the code in an
object-oriented programming language (C++). This new version introduces greater
flexibility and greater modularity, which both extends its core capabilities
and makes it far easier to add new methods and CVs. It also has a simpler
interface with the MD engines and provides a single software library containing
both tools and core facilities. Ultimately, the new code better serves the
ever-growing community of users and contributors in coping with the new
challenges arising in the field.

categories: physics.comp-ph cond-mat.stat-mech physics.bio-ph physics.chem-ph q-bio.QM


title: On discrete integrable equations of higher order

abstract:
  We study 2D discrete integrable equations of order 1 with respect to one
independent variable and $m$ with respect to another one. A generalization of
the multidimensional consistency property is proposed for this type of
equations. The examples are related to the B\"acklund--Darboux transformations
for the lattice equations of Bogoyavlensky type.


title: Multiple Meixner polynomials and non-Hermitian oscillator Hamiltonians

abstract:
  Multiple Meixner polynomials are polynomials in one variable which satisfy
orthogonality relations with respect to $r>1$ different negative binomial
distributions (Pascal distributions). There are two kinds of multiple Meixner
polynomials, depending on the selection of the parameters in the negative
binomial distribution. We recall their definition and some formulas and give
generating functions and explicit expressions for the coefficients in the
nearest neighbor recurrence relation. Following a recent construction of Miki,
Tsujimoto, Vinet and Zhedanov (for multiple Meixner polynomials of the first
kind), we construct $r>1$ non-Hermitian oscillator Hamiltonians in $r$
dimensions which are simultaneously diagonalizable and for which the common
eigenstates are expressed in terms of multiple Meixner polynomials of the
second kind.


title:
Flow equations for dense granular fluids: New insight from a
  first-principles derivation

abstract:
  We present a first-principles theory for plug-free dense granular flow. This
is done by coarse-graining directly the microscopic dynamics and deriving an
explicit relation between the macroscopic stress and strain rate tensors. The
newly derived relation not only differs significantly from that of the existing
empirical models for such flows but it also provides a novel understanding of
the effect of rigid-like rotational regions in the flow.


title: Orienting oxygen vacancies for fast catalytic reaction

abstract:
  Catalysis is indispensable to chemical processes and relevant to many aspects
of modern life. Owing to the intriguing electronic structures and good ionic
properties, multivalent transition metal oxides have attracted attention as key
catalysts for various energy and environmental applications. Here, we
demonstrate that brownmillerite strontium cobaltite (SrCoO2.5) can be a good
cathode material for sold oxide fuel cells and rechargeable batteries due to
the open oxygen frameworks. When the orientation of oxygen vacancy channels
(OVCs) is properly controlled, one can drastically increase the surface oxygen
exchange rate approximately up to two orders of magnitude. The improved oxygen
reduction kinetics is attributed to a substantial decrease in the thermal
activation energy. Importantly, the strong enhancement of crystallographic
orientation-dependent oxygen reduction reaction required the creation of
neither structural disorders nor chemical doping. Thus, our epitaxial approach
can pave a novel pathway to providing precise interpretation of oxygen
reduction reactions and to developing oxide-based energy materials.


title:
Average synaptic activity and neural networks topology: a global inverse
  problem

abstract:
  The dynamics of neural networks is often characterized by collective behavior
and quasi-synchronous events, where a large fraction of neurons fire in short
time intervals, separated by uncorrelated firing activity. These global
temporal signals are crucial for brain functioning. They strongly depend on the
topology of the network and on the fluctuations of the connectivity. We propose
a heterogeneous mean--field approach to neural dynamics on random networks,
that explicitly preserves the disorder in the topology at growing network
sizes, and leads to a set of self-consistent equations. Within this approach,
we provide an effective description of microscopic and large scale temporal
signals in a leaky integrate-and-fire model with short term plasticity, where
quasi-synchronous events arise. Our equations provide a clear analytical
picture of the dynamics, evidencing the contributions of both periodic (locked)
and aperiodic (unlocked) neurons to the measurable average signal. In
particular, we formulate and solve a global inverse problem of reconstructing
the in-degree distribution from the knowledge of the average activity field.
Our method is very general and applies to a large class of dynamical models on
dense random networks.

categories: cond-mat.dis-nn cond-mat.stat-mech physics.bio-ph q-bio.NC


title: The Pythagoras' Theorem

abstract:
  We give a brief historical overview of the famous Pythagoras' theorem and
Pythagoras. We present a simple proof of the result and dicsuss some
extensions. We follow \cite{thales}, \cite{wiki} and \cite{wiki2} for the
historical comments and sources.


title: The latitude dependence of gravitational redshift from rotating body

abstract:
  Gravitational redshift is being generally calculated without considering the
rotation of a body. Neglecting the rotation, the geometry of space time can be
described by using the spherically symmetric Schwarzschild geometry. Rotation
has great effect on general relativity, which gives new challenges on
gravitational redshift. When rotation is taken into consideration spherical
symmetry is lost and off diagonal terms appear in the metric. The geometry of
space time can be then described by using the solutions of Kerr family. In the
present paper we will discuss the gravitational redshift for rotating body by
using Kerr metric. The numerical calculations has been done under Newtonian
approximation of angular momentum. The variation of gravitational redshift from
equatorial to non - equatorial region has been calculated and its implications
are discussed in detail.


title: Asymptotic Formula for Symmetric Involutions

abstract:
  We examine the exponential generating function for the number of symmetric
involutions (A000898 in OEIS) and point out that Robinson's asymptotic formula
for its coefficients is incorrect. We further supply the correct formula.


title:
Minimal Number of Edges in Hypergraph Guaranteeing Perfect Fractional
  Matching and MMS Conjecture

abstract:
  We prove Ahlswede- Khachatrian conjecture. From this conjecture follows of
several other conjectures including Manickam-Mikl\'{o}s-Singhi conjecture.


title:
Exploiting neutron-rich radioactive ion beams to constrain the symmetry
  energy

abstract:
  The Modular Neutron Array (MoNA) and 4 Tm Sweeper magnet were used to measure
the free neutrons and heavy charged particles from the radioactive ion beam
induced 32Mg + 9Be reaction. The fragmentation reaction was simulated with the
Constrained Molecular Dynamics model(CoMD), which demonstrated that the <N/Z>
of the heavy fragments and free neutron multiplicities were observables
sensitive to the density dependence of the symmetry energy at sub-saturation
densities. Through comparison of these simulations with the experimental data
constraints on the density dependence of the symmetry energy were extracted.
The advantage of radioactive ion beams as a probe of the symmetry energy is
demonstrated through examination of CoMD calculations for stable and
radioactive beam induced reactions.


title:
Aharonov-Bohm resistance magneto-oscillations on single-nanohole
  graphite and graphene structures

abstract:
  Graphene is a stable single atomic layer material exhibiting two-dimensional
electron gas of massless Dirac fermions of high mobility. One of the intriguing
properties of graphene is a possibility of realization of the Tamm-type edge
states. These states differ from the usual surface states caused by defects,
impurities and other imperfections at the edge of the system, as well as they
differ from the magnetic edge states caused by skipping cyclotron orbits. The
Tamm states result from breaking of periodic crystal potential at the edge,
they can exist even at zero magnetic field and form a conducting band. Until
recently those states have been observed in graphene only by local STM
technique and there were no direct experiments on their contribution to
transport measurements. Here we present the experiments on Aharonov-Bohm (AB)
oscillations of resistance in a single-nanohole graphite and graphene
structures, it indicates the presence of conducting edge states cycling around
nanohole. An estimation show the penetration depth of the edge states to be as
short as about 2 nm. The oscillations persist up to temperature T=115 K and the
T-range of their existence increases with a decrease of the nanohole diameter.
The proposed mechanism of the AB oscillations based on the resonant intervalley
backscattering of the Dirac fermions by the nanohole via the Tamm states. The
experimental results are consistent with such a scenario. Our findings show a
way towards interference devices operating at high temperatures on the edge
states in graphene


title:
A new look at an old construction: constructing (simple) 3-designs from
  resolvable 2-designs

abstract:
  In 1963, Shrikhande and Raghavarao published a recursive construction for
designs that starts with a resolvable design (the "master design") and then
uses a second design (the "indexing design") to take certain unions of blocks
in each parallel class of the master design. Several variations of this
construction have been studied by different authors. We revisit this
construction, concentrating on the case where the master design is a resolvable
BIBD and the indexing design is a 3-design. We show that this construction
yields a 3-design under certain circumstances. The resulting 3-designs have
block size k = v/2 and they are resolvable. We also construct some previously
unknown simple designs by this method.


title: Sofic measures and densities of level sets

abstract:
  The Bernoulli convolution associated to the real $\beta>1$ and the
probability vector $(p_0,..,p_{d-1})$ is a probability measure $\eta_{\beta,p}$
on $\mathbb R$, solution of the self-similarity relation
$\displaystyle\eta=\sum_{k=0}^{d-1}p_k\cdot\eta\circ S_k$ where
$S_k(x)=\frac{x+k}\beta$. If $\beta$ is an integer or a Pisot algebraic number
with finite R\'enyi expansion, $\eta_{\beta,p}$ is sofic and a Markov chain is
naturally associated. If $\beta=b\in\mathbb N$ and $p_0=...=p_{d-1}=\frac1d$,
the study of $\eta_{b,p}$ is close to the study of the order of growth of the
number of representations in base $b$ with digits in $\{0,1,..,d-1\}$. In the
case $b=2$ and $d=3$ it has also something to do with the metric properties of
the continued fractions.


title: Lectures on high-frequency electrodynamics

abstract:
  The most commonnly used methods of the theoretical analysis of
electromagnetic oscillations and waves are described. The lectures are given
for the fourth-year students of Moscow Institute of Physics and Technology.
These lectures can be useful for students and undergraduate students
specialized in physics and radio engineering, as well as for experts.


title: Generalization of the Banach contraction principle

abstract:
  We introduce the concept of shifting distance functions, and we establish a
new fixed point theorem which generalizes the Banach contraction principle. An
example is provided to illustrate our result.


title:
Spatially localized attacks on interdependent networks: the existence of
  a finite critical attack size

abstract:
  Many real world complex systems such as infrastructure, communication and
transportation networks are embedded in space, where entities of one system may
depend on entities of other systems. These systems are subject to
geographically localized failures due to malicious attacks or natural
disasters. Here we study the resilience of a system composed of two
interdependent spatially embedded networks to localized geographical attacks.
We find that if an attack is larger than a finite (zero fraction of the system)
critical size, it will spread through the entire system and lead to its
complete collapse. If the attack is below the critical size, it will remain
localized. In contrast, under random attack a finite fraction of the system
needs to be removed to initiate system collapse. We present both numerical
simulations and a theoretical approach to analyze and predict the effect of
local attacks and the critical attack size. Our results demonstrate the high
risk of local attacks on interdependent spatially embedded infrastructures and
can be useful for designing more resilient systems.


title: Spectroscopic factor of the 1+, 25Al(p,g)26Si resonance at Ex=5.68 MeV

abstract:
  Nuclear shell model predictions for the proton spectroscopic factor of the
1+, Ex = 5.68 MeV level in 26Si are about fifty times smaller than the value
suggested by the measured (a,3He) cross section for the Ex = 5.69 MeV mirror
level in 26Mg, assuming purely single-particle transfer. Given that the 5.69
MeV level has been very weakly, if it all, populated in previous studies of the
simpler 25Mg(d,p) reaction, it is unclear if the (a,3He) result is a true
single-particle spectroscopic factor. If we assume the (a,3He) result, the
thermonuclear rate of the 25Al(p,g)26Si reaction would increase by factors of 6
- 50 over stellar temperatures of T = 0.05 - 0.2 GK. We examine the
implications of this enhanced rate for model predictions of nucleosynthesis in
classical nova explosions.


title: Particle-based simulations of self-motile suspensions

abstract:
  A simple model for simulating flows of active suspensions is investigated.
The approach is based on dissipative particle dynamics. While the model is
potentially applicable to a wide range of self-propelled particle systems, the
specific class of self-motile bacterial suspensions is considered as a modeling
scenario. To mimic the rod-like geometry of a bacterium, two dissipative
particle dynamics particles are connected by a stiff harmonic spring to form an
aggregate dissipative particle dynamics molecule. Bacterial motility is modeled
through a constant self-propulsion force applied along the axis of each such
aggregate molecule. The model accounts for hydrodynamic interactions between
self-propelled agents through the pairwise dissipative interactions
conventional to dissipative particle dynamics. Numerical simulations are
performed using a customized version of the open-source LAMMPS (Large-scale
Atomic/Molecular Massively Parallel Simulator) software package. Detailed
studies of the influence of agent concentration, pairwise dissipative
interactions, and Stokes friction on the statistics of the system are provided.
The simulations are used to explore the influence of hydrodynamic interactions
in active suspensions. For high agent concentrations in combination with
dominating pairwise dissipative forces, strongly correlated motion patterns and
a fluid-like spectral distributions of kinetic energy are found. In contrast,
systems dominated by Stokes friction exhibit weaker spatial correlations of the
velocity field. These results indicate that hydrodynamic interactions may play
an important role in the formation of spatially extended structures in active
suspensions.

categories: physics.flu-dyn cond-mat.soft physics.bio-ph physics.comp-ph


title: Plasma composition in a sigmoidal anemone active region

abstract:
  Using spectra obtained by the EIS instrument onboard Hinode, we present a
detailed spatially resolved abundance map of an active region (AR)-coronal hole
(CH) complex that covers an area of 359 arcsec x 485 arcsec. The abundance map
provides first ionization potential (FIP) bias levels in various coronal
structures within the large EIS field of view. Overall, FIP bias in the small,
relatively young AR is 2-3. This modest FIP bias is a consequence of the AR
age, its weak heating, and its partial reconnection with the surrounding CH.
Plasma with a coronal composition is concentrated at AR loop footpoints, close
to where fractionation is believed to take place in the chromosphere. In the
AR, we found a moderate positive correlation of FIP bias with nonthermal
velocity and magnetic flux density, both of which are also strongest at the AR
loop footpoints. Pathways of slightly enhanced FIP bias are traced along some
of the loops connecting opposite polarities within the AR. We interpret the
traces of enhanced FIP bias along these loops to be the beginning of
fractionated plasma mixing in the loops. Low FIP bias in a sigmoidal channel
above the AR's main polarity inversion line where ongoing flux cancellation is
taking place, provides new evidence of a bald patch magnetic topology of a
sigmoid/flux rope configfiuration.


title: Comparison of Fast Amplifiers for Diamond Detectors

abstract:
  The development of Chemical Vapour Deposition (CVD) diamond detectors
requests for novel signal amplifiers, capable to match the superb
signal-to-noise ratio and timing response of these detectors. Existing
amplifiers are still far away from this goal and are the dominant contributors
to the overall system noise and the main source of degradation of the energy
and timing resolution. We tested a number of commercial amplifiers designed for
diamond detector readout to identify the best solution for a particular
application. This application required a deposited energy threshold below 100
keV and timing resolution of the order of 200 ps at 200 keV. None of tested
amplifiers satisfies these requirements. The best solution to such application
found to be the Cividec C6 amplifier, which allows 100 keV minimal threshold,
but its coincidence timing resolution at 200 keV is as large as 1.2 ns.


title:
Evolution of the fermi surface of a doped topological insulator with
  carrier concentration

abstract:
  In an ideal bulk topological-insulator (TI) conducting surface states
protected by time reversal symmetry enfold an insulating crystal. However, the
archetypical TI, Bi2Se3, is actually never insulating; it is in fact a
relatively good metal. Nevertheless, it is the most studied system among all
the TIs, mainly due to its simple band-structure and large spin-orbit gap.
Recently it was shown that copper intercalated Bi2Se3 becomes superconducting
and it was suggested as a realization of a topological superconductor (TSC).
Here we use a combination of techniques that are sensitive to the shape of the
Fermi surface (FS): the Shubnikov-de Haas (SdH) effect and angle resolved
photoemission spectroscopy (ARPES) to study the evolution of the FS shape with
carrier concentration, n. We find that as n increases, the FS becomes 2D-like.
These results are of crucial importance for understanding the superconducting
properties of CuxBi2Se3.


title:
Search for invisible Higgs boson production with the CMS detector at the
  LHC

abstract:
  Results are presented for the search for invisible Higgs boson production
using the full LHC dataset corresponding to integrated luminosity of 5.1 fb^-1
and 19.6 fb^-1 of proton-proton collision data at sqrt(s)= 7 TeV and 8 TeV
(respectively) collected by the CMS detector. The invisible Higgs is searched
for in final states of missing transverse energy, with two leptons from a
recoiling Z boson. No significant excess is found beyond standard model
predictions, and limits are obtained on the branching fraction of the Higgs
boson to invisible particles.


title: The signature of line graphs and power trees

abstract:
  Let $G$ be a graph and let $A(G)$ be the adjacency matrix of $G$. The
signature $s(G)$ of $G$ is the difference between the positive inertia index
and the negative inertia index of $A(G)$. Ma et al. [Positive and negative
inertia index of a graph, Linear Algebra and its Applications 438(2013)331-341]
conjectured that $-c_3(G)\leq s(G)\leq c_5(G),$ where $c_3(G)$ and $c_5(G)$
respectively denote the number of cycles in $G$ which have length $4k+3$ and
$4k+5$ for some integers $k \ge 0$, and proved the conjecture holds for trees,
unicyclic or bicyclic graphs.
  It is known that $s(G)=0$ if $G$ is bipartite, and the signature is closely
related to the odd cycles or nonbipartiteness of a graph from the existed
results. In this paper we show that the conjecture holds for the line graph and
power trees.


title: On some generalization of the M\"obius configuration

abstract:
  The M\"obius $(8_4)$ configuration is generalized in a purely combinatorial
approach. We consider $(2n_n)$ configurations ${\goth M}_{(n,\varphi)}$
depending on a permutation $\varphi$ in the symmetric group $S_n$. Classes of
non-isomorphic configurations of this type are determined. The parametric
characterization of ${\goth M}_{(n,\varphi)}$ is given. The uniqueness of the
decomposition of ${\goth M}_{(n,\varphi)}$ into two mutually inscribed
$n$-simplices is discussed. The automorphisms of ${\goth M}_{(n,\varphi)}$ are
characterized for $n\geq 3$.


title:
Cold-nuclear-matter effects on heavy-quark production at forward and
  backward rapidity in d+Au collisions at sqrt(s_NN)=200 GeV

abstract:
  The PHENIX experiment has measured open heavy-flavor production via
semileptonic decay muons over the transverse momentum range 1 < pT < 6 GeV/c at
forward and backward rapidity (1.4 < |y| < 2.0) in d+Au and p+p collisions at
?sNN = 200 GeV. In central d+Au collisions an enhancement (suppression) of
heavy-flavor muon production is observed at backward (forward) rapidity
relative to the yield in p+p collisions scaled by the number of binary
collisions. Modification of the gluon density distribution in the Au nucleus
contributes in terms of anti-shadowing enhancement and shadowing suppression;
however, the enhancement seen at backward rapidity exceeds expectations from
this effect alone. These results, implying an important role for additional
cold nuclear matter effects, serves as a key baseline for heavy-quark
measurements in A+A collisions and in constraining the magnitude of charmonia
breakup effects at the Relativistic Heavy Ion Collider and the Large Hadron
Collider.


title:
The phase diagram of ice: a quasi-harmonic study based on a flexible
  water model

abstract:
  The phase diagram of ice is studied by a quasi-harmonic approximation. The
free energy of all experimentally known ice phases has been calculated with the
flexible q-TIP4P/F model of water. The only exception is the high pressure ice
X, in which the presence of symmetric O-H-O bonds prevents its modeling with
this empirical interatomic potential. The simplicity of our approach allows us
to study ice phases at state points of the T-P plane that have been omitted in
previous simulations using free energy methods based on thermodynamic
integration. The effect in the phase diagram of averaging the proton disorder
that appears in several ice phases has been studied. It is found particularly
relevant for ice III, at least for cell sizes typically used in phase
coexistence simulations. New insight into the capability of the employed water
model to describe the coexistence of ice phases is presented. We find that the
H-ordered ices IX and XIV, as well as the H-disordered ice XII, are
particularly stable for this water model. This fact disagrees with experimental
data. The unexpected large stability of ice IX is a property related to the
TIP4P-character of the water model. Only after omission of these three stable
ice phases, the calculated phase diagram becomes in reasonable qualitative
agreement to the experimental one in the T-P region corresponding to ice Ih,
II, III, V, and VI. The calculation of the phase diagram in the quantum and
classical limits shows that the most important quantum effect is the
stabilization of ice II due to its lower zero-point energy when compared to
that one of ices Ih, III, and V.


title: The prime divisors of the number of points on abelian varieties

abstract:
  Let A,A' be elliptic curves or abelian varieties fully of type GSp defined
over a number field K. This includes principally polarized abelian varieties
with geometric endomorphism ring Z and dimension 2 or odd. We compare the
number of points on the reductions of the two varieties. We prove that A and A'
are K-isogenous if the following condition holds for a density-one set of
primes p of K: the prime numbers dividing #A(k_p) also divide #A'(k_p). We
generalize this statement to some extent for products of such varieties. This
refines results of Hall and Perucca (2011) and of Ratazzi (2012).


title:
The VIMOS Public Extragalactic Survey (VIPERS): First Data Release of 57
  204 spectroscopic measurements

abstract:
  We present the first Public Data Release (PDR-1) of the VIMOS Public
Extragalactic Survey (VIPERS). It comprises 57 204 spectroscopic measurements
together with all additional information necessary for optimal scientific
exploitation of the data, in particular the associated photometric measurements
and quantification of the photometric and survey completeness. VIPERS is an ESO
Large Programme designed to build a spectroscopic sample of ' 100 000 galaxies
with iAB < 22.5 and 0.5 < z < 1.5 with high sampling rate (~45%). The survey
spectroscopic targets are selected from the CFHTLS-Wide five-band catalogues in
the W1 and W4 fields. The final survey will cover a total area of nearly 24
deg2, for a total comoving volume between z = 0.5 and 1.2 of ~4x10^7
h^(-3)Mpc^3 and a median galaxy redshift of z~0.8. The release presented in
this paper includes data from virtually the entire W4 field and nearly half of
the W1 area, thus representing 64% of the final dataset. We provide a detailed
description of sample selection, observations and data reduction procedures; we
summarise the global properties of the spectroscopic catalogue and explain the
associated data products and their use, and provide all the details for
accessing the data through the survey database (http://vipers.inaf.it) where
all information can be queried interactively.


title: Analogue cosmology in a hadronic fluid

abstract:
  The expansion of hadronic matter that takes place immediately after a heavy
ion collision has certain similarity with the cosmological expansion. We study
the analogue geometry of the expanding hadronic fluid, using the the formalism
of relativistic acoustic geometry. We show that the propagation of massless
pions provides a geometric analog of expanding spacetime equivalent to an open
(k=-1)FRW cosmology. Here, we study general conditions for the formation of a
trapped region with the inner boundary as a marginally trapped surface.


title:
Global Climate Modeling of the Martian water cycle with improved
  microphysics and radiatively active water ice clouds

abstract:
  Radiative effects of water ice clouds have noteworthy consequences on the
Martian atmosphere, its thermal structure and circulation. Accordingly, the
inclusion of such effects in the LMD Mars Global Climate Model (GCM) greatly
modifies the simulated Martian water cycle. The intent of this paper is to
address the impact of radiatively active clouds on atmospheric water vapor and
ice in the GCM and improve its representation. We propose a new enhanced
modeling of the water cycle, consisting of detailed cloud microphysics with
dynamic condensation nuclei and a better implementation of perennial surface
water ice. This physical modeling is based on tunable parameters. This new
version of the GCM is compared to the Thermal Emission Spectrometer
observations of the water cycle. Satisfying results are reached for both vapor
and cloud opacities. However, simulations yield a lack of water vapor in the
tropics after Ls=180{\deg} which is persistent in simulations compared to
observations, as a consequence of aphelion cloud radiative effects
strengthening the Hadley cell. Every year, our GCM simulations indicate that
permanent surface water ice on the north polar cap increases at latitudes
higher than 80{\deg}N and decreases at lower latitudes. Supersaturation above
the hygropause is predicted in line with SPICAM observations. The model also
shows for the first time that the scavenging of dust by water ice clouds alone
fails to fully account for observed dust detached layers.


title:
Multiple monopolar outflows driven by massive protostars in IRAS
  18162-2048

abstract:
  In this paper we present Combined Array for Research in Millimeter-wave
Astronomy (CARMA) 3.5 mm observations and SubMillimeter Array (SMA) 870 microns
observations toward the high-mass star-forming region IRAS 1816-2048, the core
of the HH 80/81/80N system. Molecular emission from HCN, HCO+ and SiO is
tracing two molecular outflows (the so-called Northeast and Northwest
outflows). These outflows have their origin in a region close to the position
of MM2, a millimeter source known to harbor a couple protostars. We estimate
for the first time the physical characteristics of these molecular outflows,
which are similar to those of 1000-5000 Lo protostars, suggesting that MM2
harbors high-mass protostars. High-angular resolution CO observations show an
additional outflow due southeast. We identify for the first time its driving
source, MM2(E), and see evidence of precession. All three outflows have a
monopolar appearance, but we link the NW and SE lobes, explaining their
asymmetric shape as a consequence of possible deflection.


title: Algorithmic Aspects of Switch Cographs

abstract:
  This paper introduces the notion of involution module, the first
generalization of the modular decomposition of 2-structure which has a unique
linear-sized decomposition tree. We derive an O(n^2) decomposition algorithm
and we take advantage of the involution modular decomposition tree to state
several algorithmic results. Cographs are the graphs that are totally
decomposable w.r.t modular decomposition. In a similar way, we introduce the
class of switch cographs, the class of graphs that are totally decomposable
w.r.t involution modular decomposition. This class generalizes the class of
cographs and is exactly the class of (Bull, Gem, Co-Gem, C_5)-free graphs. We
use our new decomposition tool to design three practical algorithms for the
maximum cut, vertex cover and vertex separator problems. The complexity of
these problems was still unknown for this class of graphs. This paper also
improves the complexity of the maximum clique, the maximum independant set, the
chromatic number and the maximum clique cover problems by giving efficient
algorithms, thanks to the decomposition tree. Eventually, we show that this
class of graphs has Clique-Width at most 4 and that a Clique-Width expression
can be computed in linear time.


title: The geometry of some parameterizations and encodings

abstract:
  We explore parameterizations by radicals of low genera algebraic curves. We
prove that for $q$ a prime power that is large enough and prime to $6$, a fixed
positive proportion of all genus 2 curves over the field with $q$ elements can
be parameterized by $3$-radicals. This results in the existence of a
deterministic encoding into these curves when $q$ is congruent to $2$ modulo
$3$. We extend this construction to parameterizations by $\ell$-radicals for
small odd integers $\ell$, and make it explicit for $\ell=5$.


title:
An Invariant Subspace Theorem and Invariant Subspaces of Analytic
  Reproducing Kernel Hilbert Spaces - II

abstract:
  This paper is a follow-up contribution to our work [20] where we discussed
some invariant subspace results for contractions on Hilbert spaces. Here we
extend the results of [20] to the context of n-tuples of bounded linear
operators on Hilbert spaces. Let T = (T_1, \ldots, T_n) be a pure commuting
co-spherically contractive n-tuple of operators on a Hilbert space \mathcal{H}
and \mathcal{S} be a non-trivial closed subspace of \mathcal{H}. One of our
main results states that: \mathcal{S} is a joint T-invariant subspace if and
only if there exists a partially isometric operator \Pi \in
\mathcal{B}(H^2_n(\mathcal{E}), \mathcal{H})$ such that $\mathcal{S} = \Pi
H^2_n(\mathcal{E})$, where H^2_n is the Drury-Arveson space and \mathcal{E} is
a coefficient Hilbert space and T_i \Pi = \Pi M_{z_i}, i = 1, \ldots, n. In
particular, our work addresses the case of joint shift invariant subspaces of
the Hardy space and the weighted Bergman spaces over the unit ball in
\mathbb{C}^n.


title: Utility Fair Optimisation of Antenna Tilt Angles in LTE Networks

abstract:
  We formulate adaptation of antenna tilt angle as a utility fair optimisation
task. This optimisation problem is non-convex, but in this paper we show that
under reasonable conditions it can be reformulated as a convex optimisation.
Using this insight, we develop a lightweight method for finding the optimal
antenna tilt angles, making use of measurements which are already available at
base stations, and suited to distributed implementation.


title: Quantified Constraints and Containment Problems

abstract:
  The quantified constraint satisfaction problem $\mathrm{QCSP}(\mathcal{A})$
is the problem to decide whether a positive Horn sentence, involving nothing
more than the two quantifiers and conjunction, is true on some fixed structure
$\mathcal{A}$. We study two containment problems related to the QCSP. Firstly,
we give a combinatorial condition on finite structures $\mathcal{A}$ and
$\mathcal{B}$ that is necessary and sufficient to render
$\mathrm{QCSP}(\mathcal{A}) \subseteq \mathrm{QCSP}(\mathcal{B})$. We prove
that $\mathrm{QCSP}(\mathcal{A}) \subseteq \mathrm{QCSP}(\mathcal{B})$, that is
all sentences of positive Horn logic true on $\mathcal{A}$ are true on
$\mathcal{B}$, iff there is a surjective homomorphism from
$\mathcal{A}^{|A|^{|B|}}$ to $\mathcal{B}$. This can be seen as improving an
old result of Keisler that shows the former equivalent to there being a
surjective homomorphism from $\mathcal{A}^\omega$ to $\mathcal{B}$. We note
that this condition is already necessary to guarantee containment of the
$\Pi_2$ restriction of the QCSP, that is $\Pi_2$-$\mathrm{CSP}(\mathcal{A})
\subseteq \Pi_2$-$\mathrm{CSP}(\mathcal{B})$. The exponent's bound of
${|A|^{|B|}}$ places the decision procedure for the model containment problem
in non-deterministic double-exponential time complexity. We further show the
exponent's bound $|A|^{|B|}$ to be close to tight by giving a sequence of
structures $\mathcal{A}$ together with a fixed $\mathcal{B}$, $|B|=2$, such
that there is a surjective homomorphism from $\mathcal{A}^r$ to $\mathcal{B}$
only when $r \geq |A|$. Secondly, we prove that the entailment problem for
positive Horn fragment of first-order logic is decidable. That is, given two
sentences $\varphi$ and $\psi$ of positive Horn, we give an algorithm that
determines whether $\varphi \rightarrow \psi$ is true in all structures
(models). Our result is in some sense tight, since we show that the entailment
problem for positive first-order logic (i.e. positive Horn plus disjunction) is
undecidable. In the final part of the paper we ponder a notion of Q-core that
is some canonical representative among the class of templates that engender the
same QCSP. Although the Q-core is not as well-behaved as its better known
cousin the core, we demonstrate that it is still a useful notion in the realm
of QCSP complexity classifications.


title:
Two-dimensional models of early-type fast rotating stars: new challenges
  in stellar physics

abstract:
  Two-dimensional models of rapidly rotating stars are already unavoidable for
the interpretation of interferometric or asteroseismic data of this kind of
stars. When combined with time evolution, they will allow the including of a
more accurate physics for the computation of element transport and the
determination of surface abundances. In addition, modeling the evolution of
rotation will improve gyrochronology.
  Presently, two-dimensional ESTER models predict the structure and the
large-scale flows (differential rotation and meridional circulation) of stars
with mass larger than 1.7Msun at any rotation rate. Main sequence evolution can
be mimicked by varying the hydrogen content of the convective core. Models have
been successfully tested on half a dozen of nearby fast rotating stars observed
with optical or infra-red interferometers. They are now the right tool to
investigate the oscillation spectrum of early-type fast rotators.


title: A note on inhomogeneous foliations with sections

abstract:
  We give an easy example showing that sections of a singular Riemannian
foliation on a simply connected space neither have to be isometric nor
injectively immersed.


title:
Variable Tension, Large Deflection Ideal String Model For Transverse
  Motions

abstract:
  In this study a new approach to the problem of transverse vibrations of an
ideal string is presented. Unlike previous studies, assumptions such as
constant tension, inextensibility, constant crosssectional area, small
deformations and slopes are all removed. The main result is that, despite such
relaxations in the model, not only does the final equation remain linear, but,
it is exactly the same equation obtained in classical treatments. First, an
"infinitesimals" based analysis, similar to historical methods, is given.
However, an alternative and much stronger approach, solely based on finite
quantities, is also presented. Furthermore, it is shown that the same result
can also be obtained by Lagrangian mechanics, which indicates the compatibility
of the original method with those based on energy and variational principles.
Another interesting result is the relation between the force distribution and
string displacement in static cases, which states that the force distribution
per length is proportional to the second spatial derivative of the
displacement. Finally, an equation of motion pertaining to variable initial
density and area is presented.


title: Shapes of implied volatility with positive mass at zero

abstract:
  We study the shapes of the implied volatility when the underlying
distribution has an atom at zero and analyse the impact of a mass at zero on
at-the-money implied volatility and the overall level of the smile. We further
show that the behaviour at small strikes is uniquely determined by the mass of
the atom up to high asymptotic order, under mild assumptions on the remaining
distribution on the positive real line. We investigate the structural
difference with the no-mass-at-zero case, showing how one
can--theoretically--distinguish between mass at the origin and a
heavy-left-tailed distribution. We numerically test our model-free results in
stochastic models with absorption at the boundary, such as the CEV process, and
in jump-to-default models. Note that while Lee's moment formula tells that
implied variance is at most asymptotically linear in log-strike, other
celebrated results for exact smile asymptotics such as Benaim and Friz (09) or
Gulisashvili (10) do not apply in this setting--essentially due to the
breakdown of Put-Call duality.


title: Conjugacy classes and straight elements in Coxeter groups

abstract:
  Let W be a Coxeter group. In this paper, we establish that, up to going to
some finite index normal subgroup W_0 of W, any two cyclically reduced
expressions of conjugate elements of W_0 only differ by a sequence of braid
relations and cyclic shifts. This thus provides a simple description of
conjugacy classes in W_0. As a byproduct of our methods, we also obtain a
characterisation of straight elements of W, namely of those elements w in W for
which $\ell(w^n)=n\ell(w)$ for any integer n. In particular, we generalise
previous characterisations of straight elements within the class of so-called
cyclically fully commutative (CFC) elements, and we give a shorter and more
transparent proof that Coxeter elements are straight.