title:
q-Differential equations for q-classical polynomials and
  q-Jacobi-Stirling numbers

abstract:
  We introduce, characterise and provide a combinatorial interpretation for the
so-called $q$-Jacobi-Stirling numbers. This study is motivated by their key
role in the (reciprocal) expansion of any power of a second order
$q$-differential operator having the $q$-classical polynomials as
eigenfunctions in terms of other even order operators, which we explicitly
construct in this work. The results here obtained can be viewed as the
$q$-version of those given by Everitt {\it et al.} and by the first author,
whilst the combinatorics of this new set of numbers is a $q$-version of the
Jacobi-Stirling numbers given by Gelineau and the second author.


title: On multiplicities of maximal weights of $\hat{sl}(n)$-modules

abstract:
  We determine explicitly the maximal dominant weights for the integrable
highest weight $\hat{sl}(n)$-modules $V((k-1)\Lambda_0 + \Lambda_s)$, $0 \leq s
\leq n-1$, $ k \geq 2$. We give a conjecture for the number of maximal dominant
weights of $V(k\Lambda_0)$ and prove it in some low rank cases. We give an
explicit formula in terms of lattice paths for the multiplicities of a family
of maximal dominant weights of $V(k\Lambda_0)$. We conjecture that these
multiplicities are equal to the number of certain pattern avoiding
permutations. We prove that the conjecture holds for $k=2$ and give
computational evidence for the validity of this conjecture for $k >2$.


title:
Singularities, boundary conditions and gauge link in the light cone
  gauge

abstract:
  In this work, we first review the issues on the singularities and the
boundary conditions in light cone gauge and how to regularize them properly.
Then we will further review how these singularities and the boundary conditions
can result in the gauge link at the infinity in the light cone direction in the
Drell-Yan process. Except for reviewing, we also have verified that the gauge
link at the light cone infinity has no dependence on the path not only for the
Abelian field but also for non-Abelian gauge field.


title:
Ultrahigh Q-Frequency product for optomechanical disk resonators with a
  mechanical shield

abstract:
  We report on optomechanical GaAs disk resonators with ultrahigh quality
factor - frequency product Qf. Disks standing on a simple pedestal exhibit GHz
breathing modes attaining a Qf of 10^13 measured under vacuum at cryogenic
temperature. Clamping losses are found to be the dominant source of dissipation
in this configuration. A new type of disk resonator integrating a shield within
the pedestal is then proposed and its working principles and performances
investigated by numerical simulations. For dimensions compatible with
fabrication constraints, the clamping-loss-limited Q reaches 10^7-10^9
corresponding to Qf of 10^16-10^18. This shielded pedestal approach applies to
any heterostructure presenting an acoustic mismatch.


title:
The origin of the tilted disk in the low mass X-ray binary GR Mus (XB
  1254-690)

abstract:
  We present photometric and spectroscopic observations of the low mass X-ray
binary GR Mus (XB 1254-690), and find strong evidence for the presence of a
negative superhump with a period that is 2.4+/-0.3% shorter than the orbital.
This provides further support that GR Mus indeed harbours a precessing
accretion disk (with a period of 6.74+/-0.07 day) that has retrograde
precession and is completely tilted out of the orbital plane along its line of
nodes. This tilt causes a large fraction of the gas in the accretion stream to
either over- or underflow the accretion disk instead of hitting the disk rim,
and could be a feature of all low mass X-ray binaries with characteristics
similar to GR Mus (i.e. the so-called atoll sources). Furthermore, we also find
marginal evidence for the presence of a positive superhump, suggesting that the
accretion disk in GR Mus is eccentric due to tidal resonances. If true, than
the relationship between the positive superhump period excess and the mass
ratio (q) provides a constraint of q=M_donor/M_NS=0.33-0.36. Together with the
radial velocity semi-amplitude measurements of the compact object, and previous
modeling of the inclination we obtain a mass for the neutron star of
1.2<M_NS/M_sun<1.8 (95% confidence).


title: Distance Oracles for Time-Dependent Networks

abstract:
  We present the first approximate distance oracle for sparse directed networks
with time-dependent arc-travel-times determined by continuous, piecewise
linear, positive functions possessing the FIFO property.
  Our approach precomputes $(1+\epsilon)-$approximate distance summaries from
selected landmark vertices to all other vertices in the network. Our oracle
uses subquadratic space and time preprocessing, and provides two sublinear-time
query algorithms that deliver constant and $(1+\sigma)-$approximate
shortest-travel-times, respectively, for arbitrary origin-destination pairs in
the network, for any constant $\sigma > \epsilon$. Our oracle is based only on
the sparsity of the network, along with two quite natural assumptions about
travel-time functions which allow the smooth transition towards asymmetric and
time-dependent distance metrics.


title:
Multiplication operators on $L_p$ spaces and homological triviality of
  respective category of modules

abstract:
  We give complete characterisation of topologically injective (bounded below),
topologically surjective (open mapping), isometric and coisometric (quotient
mapping) multiplication operators between $L_p$ spaces defined on different
$\sigma$-finite measure spaces. We prove that all such operators invertible
from the left or from the right. As the consequence we prove that all objects
of the category of $L_p$ spaces considered as left Banach modules over algebra
of bounded measurable functions are metrically, extremelly and relatively
projective, injective and flat.


title: Gaussian Approximation of Perturbed Chi-Square Risks

abstract:
  In this paper we show that the conditional distribution of perturbed
chi-quare risks can be approximated by certain distributions including the
Gaussian ones. Our results are of interest for conditional extreme value models
and multivariate extremes as shown in three applications.


title: On the Carroll-Chen Model

abstract:
  I argue that the Carroll-Chen cosmogenic model does not provide a plausible
scientific explanation of our universe's initial low-entropy state.


abstract:
  Inspired by their results on the Chow rings of projective K3 surfaces,
Beauville and Voisin made the following conjecture: given a projective
hyperkaehler manifold, for any algebraic cycle which is a polynomial with
rational coefficients of Chern classes of the tangent bundle and line bundles,
it is rationally equivalent to zero if and only if it is numerically equivalent
to zero. In this paper, we prove the Beauville-Voisin conjecture for
generalized Kummer varieties.


title:
An Analytical Model of Packet Collisions in IEEE 802.15.4 Wireless
  Networks

abstract:
  Numerous studies showed that concurrent transmissions can boost wireless
network performance despite collisions. While these works provide empirical
evidence that concurrent transmissions may be received reliably, existing
signal capture models only partially explain the root causes of this
phenomenon. We present a comprehensive mathematical model that reveals the
reasons and provides insights on the key parameters affecting the performance
of MSK-modulated transmissions. A major contribution is a closed-form
derivation of the receiver bit decision variable for arbitrary numbers of
colliding signals and constellations of power ratios, timing offsets, and
carrier phase offsets. We systematically explore the root causes for successful
packet delivery under concurrent transmissions across the whole parameter space
of the model. We confirm the capture threshold behavior observed in previous
studies but also reveal new insights relevant for the design of optimal
protocols: We identify capture zones depending not only on the signal power
ratio but also on time and phase offsets.


title: Anomalous Hall effect in ferromagnets with Gaussian disorder

abstract:
  Using the Kubo formalism we derived expressions and implemented the method
for calculating the anomalous Hall conductivity (AHC) in ferromagnets with
short-range Gaussian disorder directly from first-principles electronic
structure of the perfect crystal. We used this method to calculate the AHC in
bcc Fe, fcc Co, L1o-FePd, L1o-FePt as well as thin bcc Fe(001) films. Within
our approach we can transparently decompose the conductivity into intrinsic
(IC), side jump (SJ) and intrinsic skew-scattering (ISK) contributions. The
existence of ISK, which originates from asymmetric Mott scattering but is
clearly distinguishable from conventional skew-scattering in that it converges
to a finite value in clean limit, was pointed out by Sinitsyn et al. [Phys.
Rev. B 75, 045315 (2007)]. Here, we collect all contributions to the AHC in
ferromagnets which result in "scattering-independent" AHE in clean limit, and
analyze their relative magnitude from first principles calculations. By
comparing our results to existing experiments we show that the Gaussian
disorder is well suited to model various types of disorder present in real
materials, to some extent including the effect of temperature. In particular,
we show that in addition to intrinsic and side-jump AHE, the intrinsic
skew-scattering can be a major player in determining the magnitude of the AHE
in ferromagnets.


title: Kinematics of massive star ejecta in the Milky Way as traced by 26Al

abstract:
  Massive stars form in groups and their winds and supernova explosions create
superbubbles up to kpc in size. Their ejecta are important for the dynamics of
the interstellar medium and chemical evolution models. However, ejecta
kinematics and the characteristic scales in space and time are rather
unexplored beyond ~10 ka.
  Through measurement of radioactive 26Al with its decay time constant of ~10^6
years, we aim to trace the kinematics of massive-star and supernova ejecta over
million-year time scales. Our goal is to identify the mixing time scale and the
spatio-kinematics of such ejecta from the pc to kpc scale.
  We use the SPI spectrometer on INTEGRAL and its observations along the
Galactic ridge to trace the line shape of the 1808.63 keV gamma-ray line from
26Al decay. We determine line centroids and compare these to Doppler shift
expectations from large-scale systematic rotation around the Galaxy's center,
as observed in other Galactic objects.
  We measure the radial velocities of gas traced by 26Al, averaged over the
line of sight, as a function of Galactic longitude. We find substantially
higher velocities than expected from Galactic rotation, the average bulk
velocity being ~200 km s^-1 larger than the Galactic-rotation prediction. The
observed radial velocity spread implies a Doppler-broadening of the gamma-ray
line that is consistent with our measurements of the overall line width. We can
reproduce the observed characteristics with 26Al sources located along the
inner spiral arms, when we add a global blow-out into the forward direction
away from arms, such as expected from massive stars offset towards the
spiral-arm leading edge. The superbubbles-halo connection implies
angular-momentum transfer in the disk-halo system and also radial gas flows.


title: Extremes and first passage times of correlated fBm's

abstract:
  Let $\{X_i(t),t\ge0\}, i=1,2$ be two standard fractional Brownian motions
being jointly Gaussian with constant cross-correlation. In this paper we derive
the exact asymptotics of the joint survival function $$
\mathbb{P}\{\sup_{s\in[0,1]}X_1(s)>u,\ \sup_{t\in[0,1]}X_2(t)>u\} $$ as
$u\rightarrow \infty$. A novel finding of this contribution is the exponential
approximation of the joint conditional first passage times of $X_1, X_2$. As a
by-product we obtain generalizations of the Borell-TIS inequality and the
Piterbarg inequality for 2-dimensional Gaussian random fields.


title: Trapped Reeb orbits do not imply periodic ones

abstract:
  We construct a contact form on R^{2n+1}, n at least 2, equal to the standard
contact form outside a compact set and defining the standard contact structure
on all of R^{2n+1}, which has trapped Reeb orbits, including a torus invariant
under the Reeb flow, but no closed Reeb orbits. This answers a question posed
by Helmut Hofer.


title: Sterile Plus Active Neutrinos and Neutrino Oscillations

abstract:
  Using a 3 + 1 neutrino model with one sterile and the three standard active
neutrinos with a 4x4 unitary transformation matrix, U, relating flavor to mass
neutrino states, the probability of $\nu_\mu$ to $\nu_e$ transition is
estimated using sterile-active neutrino masses determined by MiniBooNE and
other experiments and sterile-active neutrino angles in the 4x4 U matrix.


title: The Convolution Theorem of Hajek and Le Cam - Revisited

abstract:
  The present paper establishes convolution theorems for regular estimators
when the limit experiment is non-Gaussian or of infnite dimension with sparse
parameter space. Applications are given for Gaussian shift experiments of
infnite dimension, the Brownian motion signal plus noise model, Levy processes
which are observed at discrete times and estimators of the endpoints of
densities with jumps. The method of proof is also of interest for the classical
convolution theorem of Hajek and Le Cam. As technical tool we present an
elementary approach for the comparison of limit experiments on standard Borel
spaces.


title: Skein Modules from Skew Howe Duality and Affine Extensions

abstract:
  We show that we can release the rigidity of the skew Howe duality process for
${\mathfrak sl}_n$ knot invariants by rescaling the quantum Weyl group action,
and recover skein modules for web-tangles. This skew Howe duality phenomenon
can be extended to the affine ${\mathfrak sl}_m$ case, corresponding to looking
at tangles embedded in a solid torus. We investigate the relations between the
invariants constructed by evaluation representations (and affinization of them)
and usual skein modules, and give tools for interpretations of annular skein
modules as sub-algebras of intertwiners for particular $U_q({\mathfrak sl}_n)$
representations. The categorification proposed in a joint work with A. Lauda
and D. Rose also admits a direct extension in the affine case.


title: Four generated, squarefree, monomial ideals

abstract:
  Let $I\supsetneq J$ be two squarefree monomial ideals of a polynomial algebra
over a field generated in degree $\geq d$, resp. $\geq d+1$ . Suppose that $I$
is either generated by three monomials of degrees $d$ and a set of monomials of
degrees $\geq d+1$, or by four special monomials of degrees $d$. If the Stanley
depth of $I/J$ is $\leq d+1$ then the usual depth of $I/J$ is $\leq d+1$ too.


title:
Potential measures of one-sided Markov additive processes with
  reflecting and terminating barriers

abstract:
  Consider a one-sided Markov additive process with an upper and a lower
barrier, where each can be either reflecting or terminating. For both defective
and non-defective processes and all possible scenarios we identify the
corresponding potential measures, which generalizes a number of results for
one-sided Levy processes. The resulting rather neat formulas have various
applications, and in particular they lead to quasi-stationary distributions of
the corresponding processes.


title:
Chemical modeling of the L1498 and L1517B prestellar cores: CO and HCO+
  depletion

abstract:
  Prestellar cores exhibit a strong chemical differentiation, which is mainly
caused by the freeze-out of molecules onto the grain surfaces. Understanding
this chemical structure is important, because molecular lines are often used as
probes to constrain the core physical properties. Here we present new
observations and analysis of the C18O (1-0) and H13CO+ (1-0) line emission in
the L1498 and L1517B prestellar cores, located in the Taurus-Auriga molecular
complex. We model these observations with a detailed chemistry network coupled
to a radiative transfer code. Our model successfully reproduces the observed
C18O (1-0) emission for a chemical age of a few 10^5 years. On the other hand,
the observed H13CO+ (1-0) is reproduced only if cosmic-ray desorption by
secondary photons is included, and if the grains have grown to a bigger size
than average ISM grains in the core interior. This grain growth is consistent
with the infrared scattered light ("coreshine") detected in these two objects,
and is found to increase the CO abundance in the core interior by about a
factor four. According to our model, CO is depleted by about 2-3 orders of
magnitude in the core center.


title: Off-shell helicity amplitudes in high-energy factorization

abstract:
  In the Catani-Ciafaloni-Hautmann high-energy factorization approach a cross
section is expressed as a convolution of unintegrated gluon densities and a
gauge-invariant hard process, in which two incoming gluons are off-shell with
momenta satisfying certain high-energy kinematics. We present two methods of
evaluating the tree-level hard process with multiple final states. The first
one assumes that only one of the gluons is off-shell and relies on the
Slavnov-Taylor identities. Such asymmetric configuration of incoming gluons is
phenomenologically important in small x probing by forward processes. The
second method deals also with two off-shell gluons and is based on the analytic
continuation of the off-shell gluons momenta to the complex space. The methods
were implemented into Monte Carlo computer programs and used in
phenomenological applications. The results of both methods are
straightforwardly related to Lipatov's effective vertices in quasi-multi-regge
kinematics.


title:
"Superluminal paradox" in wavepacket propagation and its quantum
  mechanical resolution

abstract:
  We analyse in detail the reshaping mechanism leading to apparently
"superluminal" advancement of a wave packet traversing a classically forbidden
region. In the coordinate representation, a barrier is shown to act as an
effective beamsplitter, recombining envelopes of the freely propagating pulse
with various spacial shifts. Causality ensures that none of the constituent
envelopes are advanced with respect to free propagation, yet the resulting
pulse is advanced due to a peculiar interference effect, similar to the one
responsible for "anomalous" values which occur in Aharonov's "weak
measurements". In the momentum space, the effect is understood as a bandwidth
phenomenon, where the incident pulse probes local, rather than global,
analytical properties of the transmission amplitude T (p). The advancement is
achieved when T (p) mimics locally an exponential behaviour, similar to the one
occurring in Berry's "superoscillations". Seen in a broader quantum mechanical
context, the "paradox" is but a consequence of an attempt to obtain "which
way?" information without destroying the interference between the pathways of
interest. This explains, to a large extent, the failure to adequately describe
tunnelling in terms of a single "tunnelling time".


title:
A New Continuum Formulation for Materials--Part I. The Equations of
  Motion for a Single-Component Fluid

abstract:
  The continuum equations of fluid mechanics are rederived with the intention
of keeping certain mechanical and thermodynamic concepts separate. A new
"mechanical" mass density is created to be used in computing inertial
quantities, whereas the actual mass density is treated as a thermodynamic
variable. A new set of balance laws is proposed, including a mass balance
equation with a non-convective flux. The basic principles of irreversible
thermodynamics are used to obtain linear constitutive equations that are
expansions of--not only the usual affinities involving gradients of temperature
and velocity--but also the gradient of the chemical potential. Transport
coefficients are then chosen based on an elementary diffusion model, which
yields simple constitutive laws featuring just two transport parameters: one
for the longitudinal part of the motion and one for the rotational part. The
resulting formulation differs from the Navier-Stokes-Fourier equations of fluid
motion. In order to highlight key similarities and differences between the two
approaches, several examples in fluid mechanics are treated in part II,
including sound propagation, light scattering, steady-state shock waves,
thermophoresis, and Poiseuille flow.


title: Localization on round sphere revisited

abstract:
  We consider supersymmetric gauge theories on round 3-sphere with a certain
background gauge field. The Lagrangians break the usual symmetry because the
background gauge field which we have turned on violates the isometry. In order
to maintain the supersymmetry, we choose unfamiliar charged Killing spinors as
N = 2 SUSY parameters. We perform localization calculous within this setup and
find the double sine function as we expected. We comment on more direct
relationship between theories on round sphere and squashed sphere via Weyl
transformation.


title:
The four-dimensional Martinez Alonso - Shabat equation: differential
  coverings and recursion operators

abstract:
  We apply Cartan's method of equivalence to find a contact integrable
extension for the structure equations of the symmetry pseudo-group of the
four-dimensional Martinez Alonso - Shabat equation. From the extension we
derive two differential coverings including coverings with one and two
non-removable parameters. Then we apply the same approach to construct a
recursion operator for symmetries of the equation under study.


title: Context-dependent Trust Decisions with Subjective Logic

abstract:
  A decision procedure implemented over a computational trust mechanism aims to
allow for decisions to be made regarding whether some entity or information
should be trusted. As recognised in the literature, trust is contextual, and we
describe how such a context often translates into a confidence level which
should be used to modify an underlying trust value. J{\o}sang's Subjective
Logic has long been used in the trust domain, and we show that its operators
are insufficient to address this problem. We therefore provide a
decision-making approach about trust which also considers the notion of
confidence (based on context) through the introduction of a new operator. In
particular, we introduce general requirements that must be respected when
combining trustworthiness and confidence degree, and demonstrate the soundness
of our new operator with respect to these properties.


title: Nonlinear dependence of the renormalization scale on test functions

abstract:
  Quantum electrodynamics exhibits an informal nonlinear dependence on Lorentz
invariant test function properties that determine the renormalization scale,
such as Mandelstam variables, contrary to the linear dependence on test
functions that is required by the Wightman axioms. A first example of an
alternative interacting quantum field formalism that has a comparable weakly
nonlinear dependence on Dirac spinor test functions is constructed, using
U(1)-gauge connections and U(1)-gauge invariant Dirac spinor test functions.


title: Long-Term Evolution of Decaying MHD Turbulence in the Multiphase ISM

abstract:
  Supersonic turbulence in the interstellar medium (ISM) is believed to decay
rapidly within a flow crossing time irrespective of the degree of
magnetization. However, this general consensus of decaying magnetohydrodynamic
(MHD) turbulence relies on local isothermal simulations, which are unable to
take into account the roles of global structures of magnetic fields and the
ISM. Utilizing three-dimensional MHD simulations including interstellar cooling
and heating, we investigate decaying MHD turbulence within cold neutral medium
sheets embedded in warm neutral medium. Early evolution of turbulent kinetic
energy is consistent with previous results for decaying compressible MHD
turbulence characterized by rapid energy decay with a power-law form of
$E\propto t^{-1}$ and by short decay time compared to a flow crossing time. If
initial magnetic fields are strong and perpendicular to the sheet, however,
long-term evolution of the kinetic energy shows that a significant amount of
turbulent energy ($\sim 0.2E_0$) still remains even after ten flow crossing
times for models with periodic boundary conditions. The decay rate is also
greatly reduced as the field strength increases for such initial and boundary
conditions, but not if the boundary conditions are that for a completely
isolated sheet. We analyze velocity power spectra of the remaining turbulence
to show that in-plane, incompressible motions parallel to the sheet dominate at
later times.


title:
Natural operations on the Hochschild complex of commutative Frobenius
  algebras via the complex of looped diagrams

abstract:
  We define a dg-category of looped diagrams which we use to construct
operations on the Hochschild complex of commutative Frobenius dg-algebras. We
show that we recover the operations known for symmetric Frobenius dg-algebras
constructed using Sullivan chord diagrams as well as all formal operations for
commutative algebras (including Loday's lambda operations) and prove that there
is a chain level version of a suspended Cactus operad inside the complex of
looped diagrams. This recovers the suspended BV algebra structure on the
Hochschild homology of commutative Frobenius algebras defined by Abbaspour and
proves that it comes from an action on the Hochschild chains.


title:
On the Effect of Micro-alloying on the Mechanical Properties of Metallic
  Glasses

abstract:
  "Micro-alloying", referring to the addition of small concentration of a
foreign metal to a given metallic glass, was used extensively in recent years
to attempt to improve the mechanical properties of the latter. The results are
haphazard and nonsystematic. In this paper we provide a microscopic theory of
the effect of micro-alloying, exposing the delicate consequences of this
procedure and the large parameter space which needs to be controlled. In
particular we consider two very similar models which exhibit opposite trends
for the change of the shear modulus, and explain the origins of the difference
as displayed in the different microscopic structure and properties.


title:
Bayesian rules and stochastic models for high accuracy prediction of
  solar radiation

abstract:
  It is essential to find solar predictive methods to massively insert
renewable energies on the electrical distribution grid. The goal of this study
is to find the best methodology allowing predicting with high accuracy the
hourly global radiation. The knowledge of this quantity is essential for the
grid manager or the private PV producer in order to anticipate fluctuations
related to clouds occurrences and to stabilize the injected PV power. In this
paper, we test both methodologies: single and hybrid predictors. In the first
class, we include the multi-layer perceptron (MLP), auto-regressive and moving
average (ARMA), and persistence models. In the second class, we mix these
predictors with Bayesian rules to obtain ad-hoc models selections, and Bayesian
averages of outputs related to single models. If MLP and ARMA are equivalent
(nRMSE close to 40.5% for the both), this hybridization allows a nRMSE gain
upper than 14 percentage points compared to the persistence estimation
(nRMSE=37% versus 51%).


title:
Optimally focused cold atom systems obtained using density-density
  correlations

abstract:
  Resonant absorption imaging is a common technique for detecting the
two-dimensional column density of ultracold atom systems. In many cases, the
system's thickness along the imaging direction greatly exceeds the imaging
system's depth of field, making the identification of the optimally focused
configuration difficult. Here we describe a systematic technique for bringing
Bose-Einstein condensates (BEC) and other cold-atom systems into an optimal
focus even when the ratio of the thickness to the depth of field is large: a
factor of 8 in this demonstration with a BEC. This technique relies on
defocus-induced artifacts in the Fourier-transformed density-density
correlation function (the power spectral density, PSD). The spatial frequency
at which these artifacts first appear in the PSD is maximized on focus; the
focusing process therefore both identifies and maximizes the range of spatial
frequencies over which the PSD is uncontaminated by finite-thickness effects.


title:
On the estimation of gravitational wave spectrum from cosmic domain
  walls

abstract:
  We revisit the production of gravitational waves from unstable domain walls
analyzing their spectrum by the use of field theoretic lattice simulations with
grid size $1024^3$, which is larger than the previous study. We have recognized
that there exists an error in the code used in the previous study, and the
correction of the error leads to the suppression of the spectrum of
gravitational waves at high frequencies. The peak of the spectrum is located at
the scale corresponding to the Hubble radius at the time of the decay of domain
walls, and its amplitude is consistent with the naive estimation based on the
quadrupole formula. Using the numerical results, the magnitude and the peak
frequency of gravitational waves at the present time are estimated. It is shown
that for some choices of parameters the signal of gravitational waves is strong
enough to be probed in the future gravitational wave experiments.


title: A tossed coin as quantum mechanical object

abstract:
  Comprehensive and physically consistent model of a tossed coin is presented
in terms of geometric algebra. The model clearly shows that there is nothing
elementary particle specific in the half-spin quantum mechanical formalism. It
also demonstrates what really is behind this formalism, feasibly reveals the
probabilistic meaning of wave function and shows that arithmetic of packed
objects, namely wave functions and Pauli matrices, reduces the amount of
available information.


title: Estimation of quadratic density functionals under m-dependence

abstract:
  In this paper, we study estimation of certain integral functionals of one or
two densities with samples from stationary m-dependent sequences. We consider
two types of U-statistic estimators for these functionals that are functions of
the number of epsilon-close vector observations in the samples. We show that
the estimators are consistent and obtain their rates of convergence under weak
distributional assumptions. In particular, we propose estimators based on
incomplete U-statistics which have favorable consistency properties even when
m-dependence is the only dependence condition that can be imposed on the
stationary sequences. The results can be used for divergence and entropy
estimation, and thus find many applications in statistics and applied sciences.


title: Blind Deconvolution via Maximum Kurtosis Adaptive Filtering

abstract:
  In this paper, we present an algorithm for identifying a parametrically
described destructive unknown system based on a non-gaussianity measure. It is
known that under certain conditions the output of a linear system is more
gaussian than the input. Hence, an inverse filter is searched, such that its
output is minimally gaussian. We use the kurtosis as a measure of the
non-gaussianity of the signal. A maximum of the kurtosis as a function of the
deconvolving filter coefficients is searched. The search is done iteratively
using the gradient ascent algorithm, and the coefficients at the maximum point
correspond to the inverse filter coefficients. This filter may be applied to
the distorted signal to obtain the original undistorted signal. While a similar
approach has been used before, it was always directed at a particular kind of a
signal, commonly of impulsive characteristics. In this paper a successful
attempt has been made to apply the algorithm to a wider range of signals, such
as to process distorted audio signals and destructed images. This innovative
implementation required the revelation of a way to preprocess the distorted
signal at hand. The experimental results show very good performance in terms of
recovering audio signals and blurred images, both for an FIR and IIR distorting
filters.


title:
Quantum Fingerprinting with Coherent States and a Constant Mean Number
  of Photons

abstract:
  We present a protocol for quantum fingerprinting that is ready to be
implemented with current technology and is robust to experimental errors. The
basis of our scheme is an implementation of the signal states in terms of a
coherent state in a superposition of time-bin modes. Experimentally, this
requires only the ability to prepare coherent states of low amplitude, and to
interfere them in a balanced beam splitter. The states used in the protocol are
arbitrarily close in trace distance to states of $\mathcal{O}(\log_2 n)$
qubits, thus exhibiting an exponential separation in communication complexity
compared to the classical case. The protocol uses a number of optical modes
that is proportional to the size $n$ of the input bit-strings, but a total mean
photon number that is constant and independent of $n$. Given the expended
resources, our protocol achieves a task that is provably impossible using
classical communication only. In fact, even in the presence of realistic
experimental errors and loss, we show that there exist a large range of input
sizes for which our quantum protocol requires communication that can be more
than two orders of magnitude smaller than a classical fingerprinting protocol.


title:
Ringel-Hall numbers and the Gabriel-Roiter submodules of simple
  homogeneous regular modules

abstract:
  Let k be an arbitrary field and Q an acyclic quiver of tame type. Consider
the path algebra kQ and the category of finite dimensional right modules Mod
kQ. In the first part of the paper we deduce that the Gabriel-Roiter inclusions
in preprojective indecomposables and simple homogeneous regulars (with
dimension the minimal radical vector) as well as their Gabriel-Roiter measures
are field independent. Using this result we can prove in a more general setting
a theorem by Bo Chen which states that the Gabriel-Roiter submodule of a simple
homogeneous regular (with dimension the minimal radical vector) is a
preprojective indecomposable of defect -1. The generalization consists in
considering the originally missing case $\tilde E_8$ and using arbitrary fields
(instead of algebraically closed ones). Our proof is based on the idea of
Ringel (used in the Dynkin quiver context) of comparing all possible
Ringel-Hall polynomials with the special form they take in case of a
Gabriel-Roiter inclusion. For this purpose we compute (using a program written
in GAP) a list of useful Ringel-Hall polynomials in tame cases.


title: On Metropolis Integrators for Molecular Dynamics

abstract:
  This paper invites the reader to experiment with an easy-to-use MATLAB
implementation of Metropolis integrators for Molecular Dynamics (MD)
simulation. These integrators are analysis-based, in the sense that they can
rigorously simulate dynamics along an infinitely long MD trajectory. Among
explicit integrators for MD, they seem to be the only ones that satisfy the
fundamental requirement of stability. The schemes can handle stiff or hard-core
potentials, and are straightforward to set up, apply and extend to new
situations. Potential pitfalls in high dimension are discussed, and tricks for
mitigation are given.


title: Collapse of Nonlinear Gravitational Waves in Moving-Puncture Coordinates

abstract:
  We study numerical evolutions of nonlinear gravitational waves in
moving-puncture coordinates. We adopt two different types of initial data --
Brill and Teukolsky waves -- and evolve them with two independent codes
producing consistent results. We find that Brill data fail to produce long-term
evolutions for common choices of coordinates and parameters, unless the initial
amplitude is small, while Teukolsky wave initial data lead to stable
evolutions, at least for amplitudes sufficiently far from criticality. The
critical amplitude separates initial data whose evolutions leave behind flat
space from those that lead to a black hole. For the latter we follow the
interaction of the wave, the formation of a horizon, and the settling down into
a time-independent trumpet geometry. We explore the differences between Brill
and Teukolsky data and show that for less common choices of the parameters --
in particular negative amplitudes -- Brill data can be evolved with
moving-puncture coordinates, and behave similarly to Teukolsky waves.


title: Parameterized Enumeration with Ordering

abstract:
  The classes Delay-FPT and Total-FPT recently have been introduced into
parameterized complexity in order to capture the notion of efficiently solvable
parameterized enumeration problems. In this paper we focus on ordered
enumeration and will show how to obtain Delay-FPT and Total-FPT enumeration
algorithms for several important problems. We propose a generic algorithmic
strategy, combining well-known principles stemming from both parameterized
algorithmics and enumeration, which shows that, under certain preconditions,
the existence of a so-called neighbourhood function among the solutions implies
the existence of a Delay-FPT algorithm which outputs all ordered solutions. In
many cases, the cornerstone to obtain such a neighbourhood function is a
Total-FPT algorithm that outputs all minimal solutions. This strategy is
formalized in the context of graph modification problems, and shown to be
applicable to numerous other kinds of problems.


title: The third homology of SL_2 of local rings

abstract:
  We describe the third homology of SL_2 of local rings over Z[1/2] in terms of
a refined Bloch group. We use this to derive a localization sequence for the
third homology of SL_2 of certain discrete valuation rings, and to make
explicit computations for p-adic integers and other local rings.


title: Technical advantages for weak value amplification: When less is more

abstract:
  The technical merits of weak value amplification techniques are analyzed. We
consider models of several different types of technical noise in an optical
context and show that weak value amplification techniques (which only use a
small fraction of the photons) compare favorably with standard techniques
(which uses all of them). Using the Fisher information metric, we demonstrate
that weak value techniques can put all of the Fisher information about the
detected parameter into a small portion of the events and show how this fact
alone gives technical advantages. We go on to consider a time correlated noise
model, and find that a Fisher information analysis indicates that while the
standard method can have much larger information about the detected parameter
than the postselected technique. However, the estimator needed to gather the
information is technically difficult to implement, showing that the inefficient
(but practical) signal-to-noise estimation of the parameter is usually
superior. We also describe other technical advantages unique to imaginary weak
value amplification techniques, focusing on beam deflection measurements. In
this case, we discuss combined noise types (such as detector transverse jitter,
angular beam jitter before the interferometer and turbulence) for which the
interferometric weak value technique gives higher Fisher information over
conventional methods. We go on to calculate the Fisher information of the
recently proposed photon recycling scheme for beam deflection measurements, and
show it further boosts the Fisher information by the inverse postselection
probability relative to the standard measurement case.


title: Instabilities in moderately dense granular binary mixtures

abstract:
  A linear stability analysis of the Navier-Stokes (NS) granular hydrodynamic
equations is performed to determine the critical length scale for the onset of
vortices and clusters instabilities in granular dense binary mixtures. In
contrast to previous attempts, our results (which are based on the solution to
the inelastic Enskog equation to NS order) are not restricted to nearly elastic
systems since they take into account the complete nonlinear dependence of the
NS transport coefficients on the coefficients of restitution $\alpha_{ij}$. The
theoretical predictions for the critical length scales are compared to
molecular dynamics (MD) simulations in flows of strong dissipation
($\alpha_{ij}\geq 0.7$) and moderate solid volume fractions ($\phi\leq 0.2$).
We find excellent agreement between MD and kinetic theory for the onset of
velocity vortices, indicating the applicability of NS hydrodynamics to
polydisperse flows even for strong inelasticity, finite density, and particle
dissimilarity.


title:
A remark on Kahler metrics with conical singularities along a simple
  normal crossing divisor

abstract:
  Recently it was shown by H. Guenancia and M. Paun that a singular metric
satisfying the conical Kahler-Einstein equation with a simple normal crossing
divisor is equivalent to a conical metric along that divisor. In this note, we
present an alternative proof of their theorem.


title:
Characterizing and modeling an electoral campaign in the context of
  Twitter: 2011 Spanish Presidential Election as a case study

abstract:
  Transmitting messages in the most efficient way as possible has always been
one of politicians main concerns during electoral processes. Due to the rapidly
growing number of users, online social networks have become ideal platforms for
politicians to interact with their potential voters. Exploiting the available
potential of these tools to maximize their influence over voters is one of
politicians actual challenges. To step in this direction, we have analyzed the
user activity in the online social network Twitter, during the 2011 Spanish
Presidential electoral process, and found that such activity is correlated with
the election results. We introduce a new measure to study political support in
Twitter, which we call the Relative Support. We have also characterized user
behavior by analyzing the structural and dynamical patterns of the complex
networks emergent from the mention and retweet networks. Our results suggest
that the collective attention is driven by a very small fraction of users.
Furthermore we have analyzed the interactions taking place among politicians,
observing a lack of debate. Finally we develop a network growth model to
reproduce the interactions taking place among politicians.


title:
Resummation Prediction on Higgs and Vector Boson Associated Production
  with a Jet Veto at the LHC

abstract:
  We investigate the resummation effects for the SM Higgs and vector boson
associated production at the LHC with a jet veto in soft-collinear effective
theory using "collinear anomalous" formalism. We calculate the jet vetoed
invariant mass distribution and the cross section for this process at
Next-to-Next-to-Leading-Logarithmic level, which are matched to the QCD
Next-to-Leading Order results, and compare the differences of the resummation
effects with different jet veto $p_{T}^{\rm veto}$ and jet radius $R$. Our
results show that both resummation enhancement effects and the scale
uncertainties decrease with the increasing of jet veto $p_{T}^{\rm veto}$ and
jet radius $R$, respectively. When $p_{T}^{\rm veto}=25$ GeV and $R=0.4~(0.5)$,
the resummation effects reduce the scale uncertainties of the Next-to-Leading
Order jet vetoed cross sections to about $7\%~(6\%)$, which lead to increased
confidence on the theoretical predictions. Besides, after including resummation
effects, the PDF uncertainties of jet vetoed cross section are about $7\%$.


title:
The associated weight and the essential norm of weighted composition
  operators

abstract:
  For an almost radial and typical weight $v$, we characterize the continuity
and compactness of the weighted composition operator $u C_{\varphi}$ acting on
the weighted Banach spaces of analytic functions $H_{v}^{\infty}$ in terms of
the $n$th power of the symbol $\varphi$, where $u: \mathbb{D} \to \mathbb{C}$
is an analytic function and $\varphi: \mathbb{D} \to \mathbb{D}$ is analytic.
More precisely, we extend the results of Hyv\"arinen, Kemppainen, Lindstr\"om,
Rautio and Saukko relating to the continuity and essential norm calculus of the
operator $u C_{\varphi}$.


title: Quantum phase-space representation for curved configuration spaces

abstract:
  We extend the Wigner-Weyl-Moyal phase-space formulation of quantum mechanics
to general curved configuration spaces. The underlying phase space is based on
the chosen coordinates of the manifold and their canonically conjugate momenta.
The resulting Wigner function displays the axioms of a quasiprobability
distribution, and any Weyl-ordered operator gets associated with the
corresponding phase-space function, even in the absence of continuous
symmetries. The corresponding quantum Liouville equation reduces to the
classical curved space Liouville equation in the semiclassical limit. We
demonstrate the formalism for a point particle moving on two-dimensional
manifolds, such as a paraboloid or the surface of a sphere. The latter
clarifies the treatment of compact coordinate spaces as well as the relation of
the presented phase-space representation to symmetry groups of the
configuration space.


title: Semantic Advertising

abstract:
  We present the concept of Semantic Advertising which we see as the future of
online advertising. Semantic Advertising is online advertising powered by
semantic technology which essentially enables us to represent and reason with
concepts and the meaning of things. This paper aims to 1) Define semantic
advertising, 2) Place it in the context of broader and more widely used
concepts such as the Semantic Web and Semantic Search, 3) Provide a survey of
work in related areas such as context matching, and 4) Provide a perspective on
successful emerging technologies and areas of future work. We base our work on
our experience as a company developing semantic technologies aimed at realizing
the full potential of online advertising.


title: Bayesian Decision-optimal Interval Designs for Phase I Clinical Trials

abstract:
  Interval designs are a class of phase I trial designs for which the decision
of dose assignment is determined by comparing the observed toxicity rate at the
current dose with a prespecified (toxicity tolerance) interval. If the observed
toxicity rate is located within the interval, we retain the current dose; if
the observed toxicity rate is greater than the upper boundary of the interval,
we deescalate the dose; and if the observed toxicity rate is smaller than the
lower boundary of the interval, we escalate the dose. The most critical issue
for the interval design is choosing an appropriate interval so that the design
has good operating characteristics. By casting dose finding as a Bayesian
decision-making problem, we propose new flexible methods to select the interval
boundaries so as to minimize the probability of inappropriate dose assignment
for patients. We show, both theoretically and numerically, that the resulting
optimal interval designs not only have desirable finite- and large-sample
properties, but also are particularly easy to implement in practice. Compared
to existing designs, the proposed (local) optimal design has comparable average
performance, but a lower risk of yielding a poorly performing clinical trial.


title:
Tails of plane wave spacetimes: Wave-wave scattering in general
  relativity

abstract:
  One of the most important characteristics of light in flat spacetime is that
it satisfies Huygens' principle: Initial data for the vacuum Maxwell equations
evolves sharply along null (and not timelike) geodesics. In flat spacetime,
there are no tails which linger behind expanding wavefronts. Tails generically
do exist, however, if the background spacetime is curved. The only non-flat
vacuum geometries where electromagnetic fields satisfy Huygens' principle are
known to be those associated with gravitational plane waves. This paper
investigates whether perturbations to the plane wave geometry itself also
propagate without tails. First-order perturbations to all locally-constructed
curvature scalars are indeed found to satisfy Huygens' principles. Despite
this, gravitational tails do exist. Locally, they can only perturb one plane
wave spacetime into another plane wave spacetime. A weak localized beam of
gravitational radiation passing through an arbitrarily-strong plane wave
therefore leaves behind only a slight perturbation to the waveform of the
background plane wave. The planar symmetry of that wave cannot be disturbed by
any linear tail. These results are obtained by first deriving the retarded
Green function for Lorenz-gauge metric perturbations and then analyzing its
consequences for generic initial-value problems.


title: Reconstructing projective modules from its trace ideal

abstract:
  We make a detailed study of idempotent ideals that are traces of countably
generated projective right modules. We associate to such ideals an ascending
chain of finitely generated left ideals and, dually, a descending chain of
cofinitely generated right ideals.
  The study of the first sequence allows us to characterize trace ideals of
projective modules and to show that projective modules can always be lifted
modulo the trace ideal of a projective module. As a consequence we give some
new classification results of (countably generated) projective modules over
particular classes of semilocal rings. The study of the second sequence leads
us to consider projective modules over noetherian FCR-algebras; we make some
constructions of non-trivial projective modules showing that over such rings
the behavior of countably generated projective modules that are not direct sum
of finitely generated ones is, in general, quite complex.


title:
Resonant averaging for weakly nonlinear stochastic Schr\"odinger
  equations

abstract:
  We consider the free linear Schroedinger equation on a torus $\mathbb T^d$,
perturbed by a Hamiltonian nonlinearity, driven by a random force and damped by
a linear damping: $$u_t -i\Delta u +i\nu \rho |u|^{2q_*}u = - \nu f(-\Delta) u
+ \sqrt\nu\,\frac{d}{d t}\sum_{k\in \mathbb Z^d} b_k\beta^k(t)e^{ik\cdot x} \ .
$$ Here $u=u(t,x),\ x\in\mathbb T^d$, $0<\nu\ll1$, $q_*\in\mathbb N\cup\{0\}$,
$f$ is a positive continuous function, $\rho$ is a positive parameter and
$\beta^k(t)$ are standard independent complex Wiener processes. We are
interested in limiting, as $\nu\to0$, behaviour of solutions for this equation
and of its stationary measure. Writing the equation in the slow time $\tau=\nu
t$, we prove that the limiting behaviour of the both is described by the
effective equation $$ u_\tau+ f(-\Delta) u = -iF(u)+\frac{d}{d\tau}\sum
b_k\beta^k(\tau)e^{ik\cdot x} \, $$ where the nonlinearity $F(u)$ is made out
of the resonant terms of the monomial $ |u|^{2q_*}u$. We explain the relevance
of this result for the problem of weak turbulence.


title: Dispersive blow up for nonlinear Schroedinger equations revisited

abstract:
  The possibility of finite-time, dispersive blow up for nonlinear equations of
Schroedinger type is revisited. This mathematical phenomena is one of the
possible explanations for oceanic and optical rogue waves. In dimension one,
the possibility of dispersive blow up for nonlinear Schroedinger equations
already appears in [9]. In the present work, the existing results are extended
in several ways. In one direction, the theory is broadened to include the
Davey-Stewartson and Gross-Pitaevskii equations. In another, dispersive blow up
is shown to obtain for nonlinear Schroedinger equations in spatial dimensions
larger than one and for more general power-law nonlinearities. As a by-product
of our analysis, a sharp global smoothing estimate for the integral term
appearing in Duhamel's formula is obtained.


title:
Detecting an infrared Photon within an Hour -- Transition-Edge Detector
  at ALPS-II

abstract:
  An essential design requirement of the ALPS-II experiment is the efficient
detection of single photons with a very low instrumental background of 10
{\mu}Hz. In 2011 the ALPS collaboration started to set up a TES detector
(Transition-Edge Sensor) for ALPS-II, the second phase of the experiment. Since
mid of 2013 the setup is ready for characterization in the ALPS laboratory: an
ADR cryostat (Adiabatic Demagnetization Refrigerator) as millikelvin
environment, a low noise SQUID (Superconducting Quantum Interference Device)
with electronics for read-out and a fiber-coupled high-efficient TES for
near-infrared photons as sensor. First measurements have shown a good
discrimination between noise and 1064 nm signals.

categories: physics.ins-det astro-ph.IM hep-ex hep-ph


title: The Drazin spectrum in Banach algebras

abstract:
  Several basic properties of the Drazin spectrum in Banach algebras will be
studied. As an application, some results on meromorphic Banach space operators
will be obtained.


title:
Categorical Lagrangian Grassmannians and Brauer-Picard groups of pointed
  fusion categories

abstract:
  We analyze the action of the Brauer-Picard group of a pointed fusion category
on the set of Lagrangian subcategories of its center. Using this action we
compute the Brauer-Picard groups of pointed fusion categories associated to
several classical finite groups. As an application, we construct new examples
of weakly group-theoretical fusion categories.


title: Asymptotically cylindrical manifolds with holonomy Spin(7). I

abstract:
  We construct examples of asymptotically cylindrical Riemannian 8-manifolds
with holonomy group Spin(7). To our knowledge, these are the first such
examples. The construction uses an extension to asymptotically cylindrical
setting of Joyce's existence result for torsion-free Spin(7)-structures. One
source of examples arises from `Fano-type' Kaehler 4-orbifolds with smooth
anticanonical Calabi-Yau 3-fold divisors and with compatible antiholomorphic
involution. We give examples using weighted projective spaces and calculate
basic topological invariants of the resulting Spin(7)-manifolds.


title: The Dirichlet problem for nonlocal operators

abstract:
  In this note we set up the elliptic and the parabolic Dirichlet problem for
linear nonlocal operators. As opposed to the classical case of second order
differential operators, here the "boundary data" are prescribed on the
complement of a given bounded set. We formulate the problem in the classical
framework of Hilbert spaces and prove unique solvability using standard
techniques like the Fredholm alternative.


title: New examples of hexagonal webs of circles

abstract:
  We give several new examples of hexagonal 3-webs of circles in the plane and
give a survey on such webs.


title:
Characterizing financial crisis by means of the three states random
  field Ising model

abstract:
  We propose a formula of time-series prediction by means of three states
random field Ising model (RFIM). At the economic crisis due to disasters or
international disputes, the stock price suddenly drops. The macroscopic
phenomena should be explained from the corresponding microscopic view point
because there are existing a huge number of active traders behind the crushes.
Hence, here we attempt to model the artificial financial market in which each
trader $i$ can choose his/her decision among `buying', `selling' or `staying
(taking a wait-and-see attitude)', each of which corresponds to a realization
of the three state Ising spin, namely, $S_{i}=+1$, -1 and $S_{i}=0$,
respectively. The decision making of traders is given by the Gibbs-Boltzmann
distribution with the energy function. The energy function contains three
distinct terms, namely, the ferromagnetic two-body interaction term (endogenous
information), random field term as external information (exogenous news), and
chemical potential term which controls the number of traders who are watching
the market calmly at the instance. We specify the details of the model system
from the past financial market data to determine the conjugate hyper-parameters
and draw each parameter flow as a function of time-step. Especially we will
examine to what extent one can characterize the crisis by means of a brand-new
order parameter --- `turnover' --- which is defined as the number of active
traders who post their decisions $S_{i}=1,-1$, instead of $S_{i}=0$.


title: Galaxy evolution in groups. USGC U268 and USGC U376 in the Leo cloud

abstract:
  With the aim of investigating galaxy evolution in nearby galaxy groups, we
analysed the spectral energy distribution of 24 galaxies, members of two groups
in the Leo cloud, USGC U268 and USGC U376. We estimated the ages and stellar
masses of the galaxies by fitting their total apparent magnitudes from
far-ultraviolet to near-infrared with population synthesis models. The
comparison of the results for a subsample of galaxies with smooth particle
hydrodynamic (SPH) simulations with chemo-photometric implementation, shows
that in most cases the estimated stellar masses obtained with the two different
approaches are in good agreement. The kinematical and dynamical analysis
indicates that USGC U268 is in a pre-virial collapse phase while USGC U376 is
likely in a more evolved phase towards virialization.


title:
A primal-dual hybrid gradient method for non-linear operators with
  applications to MRI

abstract:
  We study the solution of minimax problems $\min_x \max_y G(x) + \langle
K(x),y\rangle - F^*(y)$ in finite-dimensional Hilbert spaces. The functionals
$G$ and $F^*$ we assume to be convex, but the operator $K$ we allow to be
non-linear. We formulate a natural extension of the modified primal-dual hybrid
gradient method (PDHGM), originally for linear $K$, due to Chambolle and Pock.
We prove the local convergence of the method, provided various technical
conditions are satisfied. These include in particular the Aubin property of the
inverse a monotone operator at the solution. Of particular interest to us is
the case arising from reformulation of regularisation problems $\min_x
\|f-T(x)\|^2/2 + \alpha R(x)$ with the operator $T$ non-linear. For such
problems, we show that our general local convergence result holds when the
noise level of the data $f$ is low, and the regularisation parameter $\alpha$
is correspondingly small. We verify the numerical performance of the method by
applying it to problems from magnetic resonance imaging (MRI) in chemical
engineering and medicine. The specific applications are in diffusion tensor
imaging (DTI) and MR velocity imaging. These numerical studies show very
promising performance.


title: Mobility of core water in Bacillus subtilis spores by $^2$H NMR

abstract:
  Bacterial spores in a metabolically dormant state can survive long periods
without nutrients under extreme environmental conditions. The molecular basis
of spore dormancy is not well understood, but the distribution and physical
state of water within the spore is thought to play an important role. Two
scenarios have been proposed for the spore's core region, containing the DNA
and most enzymes. In the gel scenario, the core is a structured macromolecular
framework permeated by mobile water. In the glass scenario, the entire core,
including the water, is an amorphous solid and the quenched molecular diffusion
accounts for the spore's dormancy and thermal stability. Here, we use $^2$H
magnetic relaxation dispersion to selectively monitor water mobility in the
core of Bacillus subtilis spores in the presence and absence of core Mn$^{2+}$
ions. We also report and analyze the solid-state $^2$H NMR spectrum from these
spores. Our NMR data clearly support the gel scenario with highly mobile core
water (~ 25 ps average rotational correlation time). Furthermore, we find that
the large depot of manganese in the core is nearly anhydrous, with merely 1.7 %
on average of the maximum sixfold water coordination.


title: The Paradox of Two Charged Capacitors -- A New Perspective

abstract:
  It is shown that the famous paradox of two charged capacitors is successfully
resolved if all the energy changes in the system are properly considered when
some of the charges are transferred from one capacitor to the other. It happens
so even when the connecting wire has an identically zero resistance, giving
rise to no Ohmic losses in the wire. It is shown that in such a case the
"missing energy" goes into the kinetic energy of conducting charges. It is
shown that radiation plays no significant role in resolving the paradox. The
problem can be formulated and successfully resolved in a novel form, where the
capacitance of the system is increased by stretching the plates of the original
capacitor, without involving any connecting wires in a circuit. There is an
outward self-force due to mutual repulsion among charges stored within each
capacitor plate, and the work done by these self-forces during an expansion is
indeed equal to the missing energy of the capacitor system.


title: Spherical DG-functors

abstract:
  For two DG-categories A and B we define the notion of a spherical Morita
quasi-functor A -> B. We construct its associated autoequivalences: the twist T
of D(B) and the co-twist F of D(A). We give powerful sufficiency criteria for a
quasi-functor to be spherical and for the twists associated to a collection of
spherical quasi-functors to braid. Using the framework of DG-enhanced
triangulated categories, we translate all of the above to Fourier-Mukai
transforms between the derived categories of algebraic varieties. This is a
broad generalisation of the results on spherical objects in [ST01] and on
spherical functors in [Ann07]. In fact, this paper replaces [Ann07], which has
a fatal gap in the proof of its main theorem. Though conceptually correct, the
proof was impossible to fix within the framework of triangulated categories.


title: Generating all finite modular lattices of a given size

abstract:
  Modular lattices, introduced by R. Dedekind, are an important subvariety of
lattices that includes all distributive lattices. Heitzig and Reinhold
developed an algorithm to enumerate, up to isomorphism, all finite lattices up
to size 18. Here we adapt and improve this algorithm to construct and count
modular lattices up to size 24, semimodular lattices up to size 22, and
lattices of size 19. We also show that $2^{n-3}$ is a lower bound for the
number of nonisomorphic modular lattices of size $n$.


title: Metropolis Integration Schemes for Self-Adjoint Diffusions

abstract:
  We present explicit methods for simulating diffusions whose generator is
self-adjoint with respect to a known (but possibly not normalizable) density.
These methods exploit this property and combine an optimized Runge-Kutta
algorithm with a Metropolis-Hastings Monte-Carlo scheme. The resulting
numerical integration scheme is shown to be weakly accurate at finite noise and
to gain higher order accuracy in the small noise limit. It also permits to
avoid computing explicitly certain terms in the equation, such as the
divergence of the mobility tensor, which can be tedious to calculate. Finally,
the scheme is shown to be ergodic with respect to the exact equilibrium
probability distribution of the diffusion when it exists. These results are
illustrated on several examples including a Brownian dynamics simulation of DNA
in a solvent. In this example, the proposed scheme is able to accurately
compute dynamics at time step sizes that are an order of magnitude (or more)
larger than those permitted with commonly used explicit predictor-corrector
schemes.


title:
Radiative accretion shocks along nonuniform stellar magnetic fields in
  classical T Tauri stars

abstract:
  (abridged) AIMS. We investigate the dynamics and stability of post-shock
plasma streaming along nonuniform stellar magnetic fields at the impact region
of accretion columns. We study how the magnetic field configuration and
strength determine the structure, geometry, and location of the shock-heated
plasma. METHODS. We model the impact of an accretion stream onto the
chromosphere of a CTTS by 2D axisymmetric magnetohydrodynamic simulations. Our
model takes into account the gravity, the radiative cooling, and the
magnetic-field-oriented thermal conduction. RESULTS. The structure, stability,
and location of the shocked plasma strongly depend on the configuration and
strength of the magnetic field. For weak magnetic fields, a large component of
B may develop perpendicular to the stream at the base of the accretion column,
limiting the sinking of the shocked plasma into the chromosphere. An envelope
of dense and cold chromospheric material may also develop around the shocked
column. For strong magnetic fields, the field configuration determines the
position of the shock and its stand-off height. If the field is strongly
tapered close to the chromosphere, an oblique shock may form well above the
stellar surface. In general, a nonuniform magnetic field makes the distribution
of emission measure vs. temperature of the shocked plasma lower than in the
case of uniform magnetic field. CONCLUSIONS. The initial strength and
configuration of the magnetic field in the impact region of the stream are
expected to influence the chromospheric absorption and, therefore, the
observability of the shock-heated plasma in the X-ray band. The field strength
and configuration influence also the energy balance of the shocked plasma, its
emission measure at T > 1 MK being lower than expected for a uniform field. The
above effects contribute in underestimating the mass accretion rates derived in
the X-ray band.


title: Aerodynamic Drag and Gyroscopic Stability

abstract:
  This paper describes the effects on aerodynamic drag of rifle bullets as the
gyroscopic stability is lowered from 1.3 to 1.0. It is well known that a bullet
can tumble for stability less than 1.0. The Sierra Loading Manuals (4th and 5th
Editions) have previously reported that ballistic coefficient decreases
significantly as gyroscopic stability, Sg, is lowered below 1.3. These
observations are further confirmed by experiments reported here. Measured
ballistic coefficients were compared with gyroscopic stabilities computed using
the Miller Twist Rule for nearly solid metal bullets with uniform density and
computed using the Courtney-Miller formula for plastic-tipped bullets. The
relationship between Sg and drag may be used to test the applicability of
existing gyroscopic stability formulas for given bullet designs and to evaluate
the accuracy of alternate formulas in cases where the existing stability
formulas are not as accurate. The most definitive test of formulas predicting
stability will always be observation of whether bullets tumble under given
conditions. However, observations of drag changes provide valuable supplemental
information because they suggest changes in stability as conditions change. Use
of a continuous variable (drag) rather than a binary variable (tumbling) allows
insight into stability over a range of conditions where the binary variable
does not change.


title: Mean value property for nonharmonic functions

abstract:
  In this article we extend the mean value property for harmonic functions to
the nonharmonic case. In order to get the value of the function at the center
of a sphere one should integrate a certain Laplace operator power series over
the sphere. We write explicitly such series in the Euclidean case and in the
case of infinite homogeneous trees.


title: The Quark-Level Linear \sigma\ Model

abstract:
  This review of the quark-level linear \sigma model is based upon the
dynamical realization of the pseudoscalar and scalar mesons as a linear
representation of SU(2) x SU(2) chiral symmetry, with the symmetry weakly
broken by current quark masses. In its simplest SU(2) incarnation, with two
non-strange quark flavors and three colors, this nonperturbative theory, which
can be selfconsistently bootstrapped in loop order, is shown to accurately
reproduce a host of low-energy observables with only one parameter, namely the
pion decay constant f_\pi. Extending the scheme to SU(3) by including the
strange quark, equally good results are obtained for many strong,
electromagnetic, and weak processes just with two extra constants, viz. f_K and
$\langle\pi|H_{\mbox{\scriptsize weak}}|K\rangle$. Links are made with the
vector-meson-dominance model, the BCS theory of superconductivity, and
chiral-symmetry restoration at high temperature. Finally, these ideas are
cautiously generalized to the electroweak sector, including the W, Z, and Higgs
bosons, and also to CP violation.


title: A magnetic instability of the non-Abelian Sakai-Sugimoto model

abstract:
  In this follow-up paper of 1105.2217 we further discuss the occurrence of a
magnetically induced tachyonic instability of the rho meson in the two-flavour
Sakai-Sugimoto model, uplifting two remaining approximations in the previous
paper. That is, firstly, the magnetically induced splitting of the branes is
now taken into account, evaluating without approximations the symmetrized trace
which enters in the non-Abelian Dirac-Born-Infeld (DBI) action. This leads to
an extra mass generating effect for the charged heavy-light rho meson through a
holographic Higgs mechanism. Secondly, we compare the results in the
approximation to second order in the field strength to the results using the
full DBI-action. Both improvements cause an increase of the critical magnetic
field for the onset of rho meson condensation. In addition, the stability in
the scalar sector in the presence of the magnetic field is discussed.


title:
Multibump solutions of a class of second-order discrete Hamiltonian
  systems

abstract:
  For a class of second-order discrete Hamiltonian systems
$\Delta^2x(t-1)-L(t)x(t)+V'_x(t,x(t))=0$, we investigate the existence of
homoclinic orbits by applying variational method, where $L$ and $V(\cdot,x)$
are periodic functions. Further, we show that there exist either uncountable
many homoclinic orbits or multibump solutions under certain conditions.


title:
Comprehensive Evaluations of Cone-beam CT dose in Image-guided Radiation
  Therapy via GPU-based Monte Carlo simulations

abstract:
  Cone beam CT (CBCT) has been widely used for patient setup in image guided
radiation therapy (IGRT). Radiation dose from CBCT scans has become a clinical
concern. The purposes of this study are 1) to commission a GPU-based Monte
Carlo (MC) dose calculation package gCTD for Varian On-Board Imaging (OBI)
system and test the calculation accuracy, and 2) to quantitatively evaluate
CBCT dose from the OBI system in typical IGRT scan protocols. We first
conducted dose measurements in a water phantom. X-ray source model parameters
used in gCTD are obtained through a commissioning process. gCTD accuracy is
demonstrated by comparing calculations with measurements in water and in CTDI
phantoms. 25 brain cancer patients are used to study dose in a standard-dose
head protocol, and 25 prostate cancer patients are used to study dose in pelvis
protocol and pelvis spotlight protocol. Mean dose to each organ is calculated.
Mean dose to 2% voxels that have the highest dose is also computed to quantify
the maximum dose. It is found that the mean dose value to an organ varies
largely among patients. Moreover, dose distribution is highly non-homogeneous
inside an organ. The maximum dose is found to be 1~3 times higher than the mean
dose depending on the organ, and is up to 8 times higher for the entire body
due to the very high dose region in bony structures. High computational
efficiency has also been observed in our studies, such that MC dose calculation
time is less than 5 min for a typical case.


title:
Some closure operations in Zariski-Riemann spaces of valuation domains:
  a survey

abstract:
  In this survey we present several results concerning various topologies that
were introduced in recent years on spaces of valuation domains.


title:
A Pre-Trade Algorithmic Trading Model under Given Volume Measures and
  Generic Price Dynamics (GVM-GPD)

abstract:
  We make several improvements to the mean-variance framework for optimal
pre-trade algorithmic execution, by working with volume measures and generic
price dynamics. Volume measures are the continuum analogies for discrete volume
profiles commonly implemented in the execution industry. Execution then becomes
an absolutely continuous measure over such a measure space, and its
Radon-Nikodym derivative is commonly known as the Participation of Volume (PoV)
function. The four impact cost components are all consistently built upon the
PoV function. Some novel efforts are made for these linear impact models by
having market signals more properly expressed. For the opportunistic cost, we
are able to go beyond the conventional Brownian-type motions. By working
directly with the auto-covariances of the price dynamics, we remove the
Markovian restriction associated with Brownians and thus allow potential memory
effects in the price dynamics. In combination, the final execution model
becomes a constrained quadratic programming problem in infinite-dimensional
Hilbert spaces. Important linear constraints such as participation capping are
all permissible. Uniqueness and existence of optimal solutions are established
via the theory of positive compact operators in Hilbert spaces. Several typical
numerical examples explain both the behavior and versatility of the model.


title: A Comparative Analysis of Ensemble Classifiers: Case Studies in Genomics

abstract:
  The combination of multiple classifiers using ensemble methods is
increasingly important for making progress in a variety of difficult prediction
problems. We present a comparative analysis of several ensemble methods through
two case studies in genomics, namely the prediction of genetic interactions and
protein functions, to demonstrate their efficacy on real-world datasets and
draw useful conclusions about their behavior. These methods include simple
aggregation, meta-learning, cluster-based meta-learning, and ensemble selection
using heterogeneous classifiers trained on resampled data to improve the
diversity of their predictions. We present a detailed analysis of these methods
across 4 genomics datasets and find the best of these methods offer
statistically significant improvements over the state of the art in their
respective domains. In addition, we establish a novel connection between
ensemble selection and meta-learning, demonstrating how both of these disparate
methods establish a balance between ensemble diversity and performance.


title:
Performance Evaluation of Block Diagonal Preconditioners for
  Divergence-Conforming B-Spline Discretization of Stokes Equations

abstract:
  The recently introduced divergence-conforming B-spline discretizations allow
the construction of smooth discrete velocity-pressure pairs for viscous
incompressible flows that are at the same time inf-sup stable and
divergence-free. When applied to discretize Stokes equations, it generates a
symmetric and indefinite linear system of saddle-point type. Krylov subspace
methods are usually the most efficient procedures to solve such systems. One of
such methods, for symmetric systems, is the Minimum Residual Method (MINRES).
However, the efficiency and robustness of Krylov subspace methods is closely
tied to appropriate preconditioning strategies. For the discrete Stokes system,
in particular, block-diagonal strategies provide efficient preconditioners. In
this paper, we compare the performance of block-diagonal preconditioners for
several block choices. We verify how eigenvalue clustering promoted by the
preconditioning strategies affects MINRES convergence. We also compare the
number of iterations and wall-clock timings. We conclude that an incomplete
Cholesky block-diagonal preconditioning strategy with relaxed inner conjugate
gradients iterations provides the best computational strategy when compared to
other block-diagonal and global solution strategies.


title:
Uni-MUMAC: A Unified Down/Up-link MU-MIMO MAC Protocol for IEEE 802.11ac
  WLANs

abstract:
  Due to the dominance of the downlink traffic in Wireless Local Area Networks
(WLANs), a large number of previous research efforts have been put to enhance
the transmission from the Access Point (AP) to stations (STAs). The downlink
Multi-User Multiple-Input Multiple-Output (MU-MIMO) technique, supported by the
latest IEEE amendment-802.11ac, is considered as one of the key enhancements
leading WLANs to the Gigabit era. However, as cloud uploading services,
Peer-to-Peer (P2P) and telepresence applications get popular, the need for a
higher uplink capacity becomes inevitable.
  In this paper, a unified down/up-link Medium Access Control (MAC) protocol
called Uni-MUMAC is proposed to enhance the performance of IEEE 802.11ac WLANs
by exploring the multi-user spatial multiplexing technique. Specifically, in
the downlink, we implement an IEEE 802.11ac-compliant MU-MIMO transmission
scheme to allow the AP to simultaneously send frames to a group of STAs. In the
uplink, we extend the traditional one round channel access contention to two
rounds, which coordinate multiple STAs to transmit frames to the AP
simultaneously. 2-nd round Contention Window (CW2nd), a parameter that makes
the length of the 2-nd contention round elastic according to the traffic
condition, is introduced. Uni-MUMAC is evaluated through simulations in
saturated and non-saturated conditions when both downlink and uplink traffic
are present in the system. We also propose an analytic saturation model to
validate the simulation results. By properly setting CW2nd and other
parameters, Uni-MUMAC is compared to a prominent multi-user transmission scheme
in the literature. The results exhibit that Uni-MUMAC not only performs well in
the downlink-dominant scenario, but it is also able to balance both the
downlink and uplink throughput in the emerging uplink bandwidth-hungry
scenario.


title:
Multivariate and 2D Extensions of Singular Spectrum Analysis with the
  Rssa Package

abstract:
  Implementation of multivariate and 2D extensions of Singular Spectrum
Analysis (SSA) by means of the R-package Rssa is considered. The extensions
include MSSA for simultaneous analysis and forecasting of several time series
and 2D-SSA for analysis of digital images. A new extension of 2D-SSA analysis
called Shaped 2D-SSA is introduced for analysis of images of arbitrary shape,
not necessary rectangular. It is shown that implementation of Shaped 2D-SSA can
serve as a base for implementation of MSSA and other generalizations. Efficient
implementation of operations with Hankel and Hankel-block-Hankel matrices
through FFT is suggested. Examples with code fragments in R, which explain the
methodology and demonstrate the proper use of Rssa, are presented.


title:
Non-concordant links with homology cobordant zero framed surgery
  manifolds

abstract:
  We use topological surgery in dimension four to give sufficient conditions
for the zero framed surgery manifold of a 3-component link to be homology
cobordant to the 3-torus, which arises from zero framed surgery on the
Borromean rings, via a topological homology cobordism preserving the homotopy
classes of the meridians. This enables us to give new examples of 3-component
links with unknotted components and vanishing pairwise linking numbers, such
that any two of these links have homology cobordant zero surgeries in the above
sense, but the zero surgery manifolds are not homeomorphic. Moreover the links
are not concordant to one another, and in fact they can be chosen to be height
n but not height n+1 symmetric grope concordant, for each n which is at least
three.


title: On the HOMFLY polynomial of 4-plat presentations of knots

abstract:
  In this paper, I give a method to calculate the HOMFLY polynomials of knots
by using a representation of the braid group B4 into a group of 3 ? 3 matrices.
Also, I will give examples of a 2-bridge knot and a 3-bridge knot that have the
same Jone polynomial, but different HOMFLY polynomials.


title:
Learning curve for collective behavior of zero-intelligence agents in
  successive job-hunting processes with a diversity of Jaynes-Shannon's MaxEnt
  principle

abstract:
  Inspired by the unsupervised learning or self-organization in the machine
learning context, here we attempt to draw `learning curve' for the collective
behavior of job-seeking `zero-intelligence' labors in successive job-hunting
processes. Our labor market is supposed to be opened especially for university
graduates in Japan, where the students have several successive chances
n=0,1,2,... to obtain their positions within an academic (business) year. In
this sense, the `cumulative unemployment rate' in our model system is regarded
as an error-measurement in the collective intelligence of students, and the
job-hunting stage n-dependence of the error constructs a learning curve. In our
simple toy-model of probabilistic labor market, the diversity of students'
behavior is built-in by means of the Jaynes-Shannon's MaxEnt (Maximum Entropy)
principle. Then, we discuss the speed of convergence for the error-measurement,
where we consider a scenario in which the students do not use any information
about the result of job-hunting processes in the previous stage. Our approach
enables us to examine the existence of the condition on which macroscopic
quantity, say, `stage-wise unemployment rate' becomes `scale-invariant' in the
sense that it does not depend on the job-hunting stage n. From the macroscopic
view point, the problem could be regarded as a human resource allocation.


title:
Exact spectral function for hole-magnon coupling in the ferromagnetic
  CuO$_3$-like chain

abstract:
  We present the exact spectral function for a single oxygen hole with spin
opposite to ferromagnetic order within a one-dimensional CuO$_{3}$-like spin
chain. We find that local Kondo-like exchange interaction generates five
different states in the strong coupling regime. It stabilizes a spin polaron
which is a bound state of a moving charge dressed by magnon excitations, with
essentially the same dispersion as predicted by mean field theory. We then
examine in detail the evolution of the spectral function for increasing
strength of the hole-magnon interaction. We also demonstrate that the $s$ and
$p$ symmetry of orbital states in the conduction band are essentially
equivalent to each other and find that the simplified models do not suffice to
reproduce subtle aspects of hole-magnon coupling in the charge-transfer model.


title: Schubert calculus and torsion explosion

abstract:
  We observe that certain numbers occurring in Schubert calculus for SL_n also
occur as entries in intersection forms controlling decompositions of Soergel
bimodules and parity sheaves in higher rank. These numbers grow exponentially.
This observation gives many counterexamples to Lusztig's conjecture on the
characters of simple rational modules for SL_n over a field of positive
characteristic. We explain why our examples also give counter-examples to the
James conjecture on decomposition numbers for symmetric groups.


title:
Descartes' rule of signs and the identifiability of population
  demographic models from genomic variation data

abstract:
  The sample frequency spectrum (SFS) is a widely-used summary statistic of
genomic variation in a sample of homologous DNA sequences. It provides a highly
efficient dimensional reduction of large-scale population genomic data and its
mathematical dependence on the underlying population demography is well
understood, thus enabling the development of efficient inference algorithms.
However, it has been recently shown that very different population demographies
can actually generate the same SFS for arbitrarily large sample sizes. Although
in principle this nonidentifiability issue poses a thorny challenge to
statistical inference, the population size functions involved in the
counterexamples are arguably not so biologically realistic. Here, we revisit
this problem and examine the identifiability of demographic models under the
restriction that the population sizes are piecewise-defined where each piece
belongs to some family of biologically-motivated functions. Under this
assumption, we prove that the expected SFS of a sample uniquely determines the
underlying demographic model, provided that the sample is sufficiently large.
We obtain a general bound on the sample size sufficient for identifiability;
the bound depends on the number of pieces in the demographic model and also on
the type of population size function in each piece. In the cases of
piecewise-constant, piecewise-exponential and piecewise-generalized-exponential
models, which are often assumed in population genomic inferences, we provide
explicit formulas for the bounds as simple functions of the number of pieces.
Lastly, we obtain analogous results for the "folded" SFS, which is often used
when there is ambiguity as to which allelic type is ancestral. Our results are
proved using a generalization of Descartes' rule of signs for polynomials to
the Laplace transform of piecewise continuous functions.


title:
Maximization of the first nontrivial eigenvalue on the surface of genus
  two

abstract:
  The first nontrivial eigenvalue of the Laplacian can be considered as a
functional on the space of all Riemannian metrics of unit volume on a fixed
surface. In this paper we prove that for the surface of genus 2 the supremum of
this functional is equal to $16\pi$. This provides a positive answer to the
conjecture by Jakobson, Levitin, Nadirashvili, Nigam and Polterovich.


title: Small Amplitude Periodic Solutions of Klein-Gordon Equations

abstract:
  We consider a class of nonlinear Klein-Gordon equations
$u_{tt}=u_{xx}-u+f(u)$ and obtain a family of small amplitude periodic
solutions, where the temporal and spatial period have different scales.


title:
Compressible Euler equation with damping on Torus in arbitrary
  dimensions

abstract:
  We study the exponential stability of constant steady state of isentropic
compressible Euler equation with damping on $\mathbb T^n$. The local existence
of solutions is based on semigroup theory and some commutator estimates. We
propose a new method instead of energy estimates to study the stability, which
works equally well for any spatial dimensions.


title:
Multi-Layer Potfit: An Accurate Potential Representation for Efficient
  High-Dimensional Quantum Dynamics

abstract:
  The multi-layer multi-configuration time-dependent Hartree method (ML-MCTDH)
is a highly efficient scheme for studying the dynamics of high-dimensional
quantum systems. Its use is greatly facilitated if the Hamiltonian of the
system possesses a particular structure through which the multi-dimensional
matrix elements can be computed efficiently. In the field of quantum molecular
dynamics, the effective interaction between the atoms is often described by
potential energy surfaces (PES), and it is necessary to fit such PES into the
desired structure. For high-dimensional systems, the current approaches for
this fitting process either lead to fits that are too large to be practical, or
their accuracy is difficult to predict and control.
  This article introduces multi-layer Potfit (MLPF), a novel fitting scheme
that results in a PES representation in the hierarchical tensor (HT) format.
The scheme is based on the hierarchical singular value decomposition, which can
yield a near-optimal fit and give strict bounds for the obtained accuracy.
Here, a recursive scheme for using the HT-format PES within ML-MCTDH is
derived, and theoretical estimates as well as a computational example show that
the use of MLPF can reduce the numerical effort for ML-MCTDH by orders of
magnitude, compared to the traditionally used Potfit representation of the PES.
Moreover, it is shown that MLPF is especially beneficial for high-accuracy PES
representations, and it turns out that MLPF leads to computational savings
already for comparatively small systems with just four modes.


title: Avoidance of a Landau Pole by Flat Contributions in QED

abstract:
  We consider massless Quantum Electrodynamics in momentum scheme and carry
forward an approach based on Dyson-Schwinger equations to approximate both the
$\beta$-function and the renormalized photon self-energy [Y11]. Starting from
the Callan-Symanzik equation, we derive a renormalization group (RG) recursion
identity which implies a non-linear ODE for the anomalous dimension and extract
a sufficient but not necessary criterion for the existence of a Landau pole.
This criterion implies a necessary condition for QED to have no such pole.
Solving the differential equation exactly for a toy model case, we integrate
the corresponding RG equation for the running coupling and find that even
though the $\beta$-function entails a Landau pole it exhibits a flat
contribution capable of decreasing its growth, in other cases possibly to the
extent that such a pole is avoided altogether. Finally, by applying the
recursion identity, we compute the photon propagator and investigate the effect
of flat contributions on both spacelike and timelike photons.


title: Energy Fluxes during Dynamo Reversals

abstract:
  Using direct numerical simulations of the equations of magnetohydrodynamics,
we study reversals of the magnetic field generated by the flow of an
electrically conducting fluid in a sphere. We show that at low magnetic Prandtl
numbers, Pm=0.5, the decrease of magnetic energy, ohmic dissipation and power
of the Lorentz force during a reversal is followed by an increase of the power
injected by the force driving the flow and an increase of viscous dissipation.
Cross correlations show that the Lorentz energy flux is in advance with respect
to the other energy fluxes. We also observe that during a reversal, the maximum
of the magnetic energy density migrates from one hemisphere to the other and
comes back to its initial position, in agreement with recent experimental
observations. For larger magnetic Prandtl numbers (Pm= 1, 2), the magnetic
field reversals do not display these trends and strongly differ one from
another.


title: Process Characterisation with Monte-Carlo Wave-Functions

abstract:
  We present a numerically efficient method for the characterisation of a
quantum process subject to dissipation and noise. The master equation evolution
of a maximally entangled state of the quantum system and a non-evolving ancilla
system is simulated by Monte-Carlo wave-functions. We show how each stochastic
state vectors provides quantities that are readily combined into an average
process \chi-matrix. Our method significantly reduces the computational
complexity in comparison with standard characterisation methods. It also
readily provides an upper bound on the trace distance between the ideal and
simulated process based on the evolution of only a single wave function of the
entangled system.


title: Capturing pattern bi-stability dynamics in delay-coupled swarms

abstract:
  Swarms of large numbers of agents appear in many biological and engineering
fields. Dynamic bi-stability of co-existing spatio-temporal patterns has been
observed in many models of large population swarms. However, many reduced
models for analysis, such as mean-field (MF), do not capture the bifurcation
structure of bi-stable behavior. Here, we develop a new model for the dynamics
of a large population swarm with delayed coupling. The additional physics
predicts how individual particle dynamics affects the motion of the entire
swarm. Specifically, (1) we correct the center of mass propulsion physics
accounting for the particles velocity distribution; (2) we show that the model
we develop is able to capture the pattern bi-stability displayed by the full
swarm model.


title:
From self-adjoint to non self-adjoint harmonic oscillators: physical
  consequences and mathematical pitfalls

abstract:
  Using as a prototype example the harmonic oscillator we show how losing
self-adjointness of the hamiltonian $H$ changes drastically the related
functional structure. In particular, we show that even a small deviation from
strict self-adjointness of $H$ produces two deep consequences, not well
understood in the literature: first of all, the original orthonormal basis of
$H$ splits into two families of biorthogonal vectors. These two families are
complete but, contrarily to what often claimed for similar systems, none of
them is a basis for the Hilbert space $\Hil$. Secondly, the so-called metric
operator is unbounded, as well as its inverse.
  In the second part of the paper, after an extension of some previous results
on the so-called $\D$ pseudo-bosons, we discuss some aspects of our extended
harmonic oscillator from this different point of view.


title:
Equivariant and self-similar standing waves for a Hamiltonian
  hyperbolic-hyperbolic spin-field system

abstract:
  In this paper we study the existence of special symmetric solutions to a
Hamiltonian hyperbolic-hyperbolic coupled spin-field system, where the spins
are maps from $\mathbb R^{2+1}$ into the sphere $\S^2$ or the pseudo-sphere
$\H^2$. This model was introduced in \cite{Martina} and it is also known as the
{\it hyperbolic-hyperbolic generalized Ishimori system}. Relying on the
hyperbolic coordinates introduced in \cite{KNZ11}, we prove the existence of
equivariant standing waves in both regular hyperbolic coordinates as well as
similarity variables, and describe their asymptotic behaviour.


title:
Distributed coordination of self-organizing mechanisms in communication
  networks

abstract:
  The fast development of the Self-Organizing Network (SON) technology in
mobile networks renders the problem of coordinating SON functionalities
operating simultaneously critical. SON functionalities can be viewed as control
loops that may need to be coordinated to guarantee conflict free operation, to
enforce stability of the network and to achieve performance gain. This paper
proposes a distributed solution for coordinating SON functionalities. It uses
Rosen's concave games framework in conjunction with convex optimization. The
SON functionalities are modeled as linear Ordinary Differential Equation
(ODE)s. The stability of the system is first evaluated using a basic control
theory approach. The coordination solution consists in finding a linear map
(called coordination matrix) that stabilizes the system of SON functionalities.
It is proven that the solution remains valid in a noisy environment using
Stochastic Approximation. A practical example involving three different SON
functionalities deployed in Base Stations (BSs) of a Long Term Evolution (LTE)
network demonstrates the usefulness of the proposed method.


title: Metaplectic sheets and caustic traversals in the Weyl representation

abstract:
  The quantum Hamiltonian generates in time a family of evolution operators.
Continuity of this family holds within any choice of representation and, in
particular, for the Weyl propagator, even though its simplest semiclassical
approximation may develop caustic singularities. The phase jumps of the Weyl
propagator across caustics have not been previously determined.
  The semiclassical appproximation relies on individual classical trajectories
together with their neighbouring tangent map. Based on the latter, one defines
a continuous family of unitary tangent propagators, with an exact Weyl
representation that is close to the full semiclassical approximation in an
appropriate neighbourhood. The phase increment of the semiclassical Weyl
propagator, as a caustic is crossed, is derived from the facts that the
corresponding family of tangent operators belong to the metaplectic group and
that the products of the tangent propagators are obtained from Gaussian
integrals. The Weyl representation of the metaplectic group is here presented,
with the correct phases determined within an intrinsic ambiguity for the
overall sign. The elements that fully determine the phase increment across a
particular caustic are then analysed.


title:
Securing the IEEE 802.16 OFDM WiMAX PHYSICAL AND MAC Layer Using STBC
  Coding and Encryption

abstract:
  This work proposes model design in securing the IEEE 802.16 WiMAX Physical
and MAC layer, using Orthogonal Frequency Division Multiplexing (OFDM) and STBC
model. Typically, it addresses the physical and MAC layer security concerns,
using a Space Time Block Coding (STBC), link encryption, and Message
Authentication Code (MAC) technique. The model conforms to Multiple Input
Single Output (MISO) fading channels which model two or more transmitters and a
receiver in multiuser environment. The two fading link parameters are assumed
to be same. Channel estimate for each link, in combination to the received
signal is based on Reed Solomon Convolution Coding (RS-CC) algorithm, which
occurs as a result of the Space-Time Diversity Combiner block. In addition the
model explore using communication blocks to measure and display bit error rate
after encryption algorithm and Message Authentication Code (MAC) have been
adapted in Forward Error Correction (FEC) mode. Channel SNR and estimation in
rate ID is applied. The final results shows authentication, and the
Reed-Solomon decoding of the final information or data received.


title:
Boundary conditions and subelliptic estimates for geometric
  Kramers-Fokker-Planck operators on manifolds with boundaries

abstract:
  This article is concerned with maximal accretive realizations of geometric
Kramers-Fokker-Planck operators on manifolds with boundaries. A general class
of boundary conditions is introduced which ensures the maximal accretivity and
some global subelliptic estimates. Those estimates imply nice spectral
properties as well as exponential decay properties for the associated
semigroup. Admissible boundary conditions cover a wide range of applications
for the usual scalar Kramer-Fokker-Planck equation or Bismut's hypoelliptic
Laplacian.


title: A Note on BSDEs with singular coefficients

abstract:
  In this Note we study a class of BSDEs which admits a particular singularity
in their driver. More precisely, we assume that the driver is not integrable
and degenerates when approaching to the terminal time of the equation.