title:
Vesicularity, bubble formation and noble gas fractionation during MORB
  degassing

abstract:
  The objective of this study is to use molecular dynamics simulation (MD) to
evaluate the vesicularity and noble gas fractionation, and to shed light on
bubble formation during MORB degassing. A previous simulation study (Guillot
and Sator (2011) GCA 75, 1829-1857) has shown that the solubility of CO2 in
basaltic melts increases steadily with the pressure and deviates significantly
from Henry's law at high pressures (e.g. 9.5 wt% CO2 at 50 kbar as compared
with 2.5 wt% from Henry's law). From the CO2 solubility curve and the equations
of state of the two coexisting phases (silicate melt and supercritical CO2),
deduced from the MD simulation, we have evaluated the evolution of the
vesicularity of a MORB melt at depth as function of its initial CO2 contents.
An excellent agreement is obtained between calculations and data on MORB
samples collected at oceanic ridges. Moreover, by implementing the test
particle method (Guillot and Sator (2012) GCA 80, 51-69), the solubility of
noble gases in the two coexisting phases (supercritical CO2 and CO2-saturated
melt), the partitioning and the fractionation of noble gases between melt and
vesicles have been evaluated as function of the pressure. We show that the
melt/CO2 partition coefficients of noble gases increase significantly with the
pressure whereas the large distribution of the 4He/40Ar* ratio reported in the
literature is explained if the magma experiences a suite of vesiculation and
vesicle loss during ascent. By applying a pressure drop to a volatile bearing
melt, the MD simulation reveals the main steps of bubble formation and noble
gas transfer at the nanometric scale. A key result is that the transfer of
noble gases is found to be driven by CO2 bubble nucleation, a finding which
suggests that the diffusivity difference between He and Ar in the degassing
melt has virtually no effect on the 4He/40Ar* ratio measured in the vesicles.


title:
Intelligent Compaction and Quality Assurance of Roller Measurement
  Values utilizing Backfitting and Multiresolution Scale Space Analysis

abstract:
  Modern earthwork compaction rollers collect location and compaction
information as they traverse a compaction site. These roller measurement values
present a challenging spatio-temporal statistical problem that requires careful
implementation of a proper stochastic model and estimation procedure. Heersink
and Furrer (2013) proposed a sequential, spatial mixed-effects model and a
sequential, spatial backfitting routine for estimation of the modeling terms
for such data. The estimated fields produced from this backfitting procedure
are analyzed using a multiresolution scale space analysis developed by
Holmstrom et al. (2011). This image analysis is proposed as a viable solution
to improved intelligent compaction and quality assurance of the compaction
process.


title: Resonances for 1D massless Dirac operators

abstract:
  We consider the 1D massless Dirac operator on the real line with compactly
supported potentials. We study resonances as the poles of scattering matrix or
equivalently as the zeros of modified Fredholm determinant. We obtain the
following properties of the resonances: 1) asymptotics of counting function, 2)
estimates on the resonances and the forbidden domain, 3) the trace formula in
terms of resonances.


title:
All-optically induced currents resulting from frequency modulated
  coherent polarization

abstract:
  We employ polarization-shaped ultrafast optical pulses to generate
photocurrents which only arise if the optically induced coherent polarization
is frequency modulated. This frequency modulation is obtained via detuned
excitation of light-hole excitons in (110)-oriented GaAs quantum wells. The
observed photocurrents vanish for resonant excitation of excitons and reverse
their direction with a change of the sign of detuning. Moreover, the currents
do not exist for continuous-wave excitation. Our work reveals the existence of
a new class of photocurrents and visualizes the complexity of current response
tensors. This is helpful for the better understanding of optically induced
microscopic transport in semiconductors.


title: RX J0648.0--4418: the fastest-spinning white dwarf

abstract:
  RX J0648.0-4418 is a post common-envelope X-ray binary composed of a hot
subdwarf and one of the most massive white dwarfs with a dynamical mass
measurement (1.28+/-0.05 M_sun). This white dwarf, with a spin period of 13.2
s, rotates more than twice faster than the white dwarf in the cataclysmic
variable AE Aqr. The current properties of these two binaries, as well as their
future evolution, are quite different, despite both contain a fast-spinning
white dwarf. RX J0648.0-4418 could be the progenitor of either a Type Ia
supernova or of a non-recycled millisecond pulsars.


title: The Betti numbers of Stanley-Reisner ideals of simplicial trees

abstract:
  We provide a simple method to compute the Betti numbers if the
Stanley-Reisner ideal of a simplicial tree and its Alexander dual.


title: Transport techniques for non-Gaussianity

abstract:
  This proceedings contribution provides a brief update on the transport
approach to calculating the statistics of perturbations produced during
inflation. It is based in particular on work in collaboration with Gemma
Anderson and David Seery.


title: Undiscounted Markov chain BSDEs to stopping times

abstract:
  We consider Backward Stochastic Differential Equations in a setting where
noise is generated by a countable state, continuous time Markov chain, and the
terminal value is prescribed at a stopping time. We show that, given sufficient
integrability of the stopping time and a growth bound on the terminal value and
BSDE driver, these equations admit unique solutions satisfying the same growth
bound (up to multiplication by a constant). This holds without assuming that
the driver is monotone in y, that is, our results do not require that the
terminal value be discounted at some uniform rate. We show that the conditions
are satisfied for hitting times of states of the chain, and hence present some
novel applications of the theory of these BSDEs.


title: Volatile and refractory abundances of solar analogs with planets

abstract:
  We present a detailed abundance analysis of high-quality HARPS, UVES and UES
spectra of 95 solar analogs, 33 with and 62 without detected planets. These
spectra have S/N > 350. We investigate the possibility that the possible
presence of terrestrial planets could affect the volatile-to-refratory
abundance ratios. We do not see clear differences between stars with and
without planets, either in the only seven solar twins or even when considering
the whole sample of 95 solar analogs in the metallicity range -0.3< [Fe/H] <
0.5 . We demonstrate that after removing the Galactic chemical evolution
effects the possible differences between stars with and without planets in
these samples practically disappear and the volatile-to-refractory abundance
ratios are very similar to solar values. We investigate the abundance ratios of
volatile and refractory elements versus the condensation temperature of this
sample of solar analogs, in particular, paying a special attention to those
stars harbouring super-Earth-like planets.


title: Dynamics of Hilbert nonexpansive maps

abstract:
  In his work on the foundations of geometry, Hilbert observed that a formula
which appeared in works by Beltrami, Cayley, and Klein, gives rise to a
complete metric on any bounded convex domain. Some decades later, Garrett
Birkhoff and Hans Samelson noted that this metric has interesting applications,
when considering certain maps of convex cones that contract the metric. Such
situations have since arisen in many contexts, pure and applied, and could be
called nonlinear Perron-Frobenius theory. This note centers around one
dynamical aspect of this theory.


title: TASI Lectures on Cosmological Perturbations

abstract:
  We present a self-contained summary of the theory of linear cosmological
perturbations. We emphasize the effect of the six parameters of the minimal
cosmological model, first, on the spectrum of Cosmic Microwave Background
temperature anisotropies, and second, on the linear matter power spectrum. We
briefly review at the end the possible impact of a few non-minimal dark matter
and dark energy models.


title:
Dichotomization invariant log-mean linear parameterization for discrete
  graphical models of marginal independence

abstract:
  We extend the log-mean linear parameterization introduced by Roverato et al.
(2013) for binary data to discrete variables with arbitrary number of levels,
and show that also in this case it can be used to parameterize bi-directed
graph models. Furthermore, we show that the log-mean linear parameterization
allows one to simultaneously represent marginal independencies among variables
and marginal independencies that only appear when certain levels are collapsed
into a single one. We illustrate the application of this property by means of
an example based on genetic association studies involving single-nucleotide
polymorphisms. More generally, this feature provides a natural way to reduce
the parameter count, while preserving the independence structure, by means of
substantive constraints that give additional insight into the association
structure of the variables.


title: Measurements of the Top Quark Pair-Production Cross Section

abstract:
  Measurements of the inclusive and differential cross section for the
production of top quark pairs in proton-(anti)proton collision at
center-of-mass energies of 1.96, 7.0 and 8.0 TeV are presented and compared
with the latest theory predictions and Monte-Carlo models. In addition, first
measurements of the production of top quark pairs in association with
additional jets or with a boson are highlighted. All measurements are in good
agreement with the Standard Model.


title:
Effect of magnetism on kinetics of "gamma"-"alpha" transformation and
  pattern formation in iron

abstract:
  Kinetics of polymorphous "gamma"-"alfa" transformation in Fe is studied
numerically within a model taking into account both lattice and magnetic
degrees of freedom, based on first-principle calculations of the total energy
for different magnetic states. It is shown that magnetoelastic phenomena,
namely, a strong sensitivity of the potential relief along the Bain deformation
path to the magnetic state, are crucial for the picture of the transformation.
With the temperature increase, a scenario of the phase transformation evolves
from a homogeneous lattice instability at T<Ms (Ms is the temperature of the
beginning of the martensitic transformation) to the growth and nucleation of
embryos of the new phase at T>Ms. In the latter case, a stage of formation of a
tweed-like structure occurs, with a strong short-range order and slow
interphase fluctuations.


title:
Heat kernels on regular graphs and generalized Ihara zeta function
  formulas

abstract:
  We establish a new formula for the heat kernel on regular trees in terms of
classical I-Bessel functions. Although the formula is explicit, and a proof is
given through direct computation, we also provide a conceptual viewpoint using
the horocyclic transform on regular trees. From periodization, we then obtain a
heat kernel expression on any regular graph. From spectral theory, one has
another expression for the heat kernel as an integral transform of the spectral
measure. By equating these two formulas and taking a certain integral
transform, we obtain several generalized versions of the determinant formula
for the Ihara zeta function associated to finite or infinite regular graphs.
Our approach to the Ihara zeta function and determinant formula through heat
kernel analysis follows a similar methodology which exists for quotients of
rank one symmetric spaces.


title:
A CR-hydro-NEI Model of Multi-wavelength Emission from the Vela Jr.
  Supernova Remnant (SNR RX J0852.0-4622)

abstract:
  Based largely on energy budget considerations and the observed cosmic-ray
(CR) ionic composition, supernova remnant (SNR) blast waves are the most likely
sources of CR ions with energies at least up to the "knee" near 3 PeV. Shocks
in young shell-type TeV-bright SNRs are surely producing TeV particles, but the
emission could be dominated by ions producing neutral pion-decay emission or
electrons producing inverse-Compton gamma-rays. Unambiguously identifying the
GeV-TeV emission process in a particular SNR will not only help pin down the
origin of CRs, it will add significantly to our understanding of the diffusive
shock acceleration (DSA) mechanism and improve our understanding of supernovae
and the impact SNRs have on the circumstellar medium. In this study, we
investigate the Vela Jr. SNR, an example of TeV-bright non-thermal SNRs. We
perform hydrodynamic simulations coupled with non-linear DSA and
non-equilibrium ionization near the forward shock (FS) to confront currently
available multi-wavelength data. We find, with an analysis similar to that used
earlier for SNR RX J1713.7-3946, that self-consistently modeling the thermal
X-ray line emission with the non-thermal continuum in our one-dimensional model
strongly constrains the fitting parameters, and this leads convincingly to a
leptonic origin for the GeV-TeV emission for Vela Jr. This conclusion is
further supported by applying additional constraints from observation,
including the radial brightness profiles of the SNR shell in TeV gamma-rays,
and the spatial variation of the X-ray synchrotron spectral index. We will
discuss implications of our models on future observations by the
next-generation telescopes.


title: Some aspects of generalized modified gravity models

abstract:
  In the present work, we review some general aspects of modified gravity
theories, investigating mathematical and physical properties and, more
specifically, the feature of viable and realistic models able to reproduce the
dark energy epoch and the early-time inflation. We will discuss the black hole
solutions in generalized theories of gravity: it is of fundamental interest to
understand how properties and laws of black holes in General Relativity can be
addressed in the framework of modified theories. In particular, we will discuss
the energy issue and the possibility to derive the First Law of thermodynamics
from the field equations. Then, in the analysis of cosmological solutions, we
will pay a particular attention to the occurrence of finite-time future
singularities and to the possibility to avoid them in $\mathcal
F(R,G)$-gravity. Furthermore, realistic models of $F(R)$-gravity will be
analyzed in the detail. A general feature occurring in matter era will be
shown, namely the high derivatives of Hubble parameter may be influenced by the
high frequency oscillation of the dark energy and some correction term is
required in order to stabilize the theory at high redshift. The inflationary
scenario is also carefully analyzed and an unified description of the universe
is risen. In the final part of the work, we will have a look at the last
developments in modified gravity, namely we will investigate cosmological and
black hole solutions in a covariant field theory of gravity and we will
introduce the extended "teleparallel" $F(T)$-gravity theories. A nice
application to the dark matter problem will be presented.


title: A generalization of Combinatorial Nullstellensatz

abstract:
  In this note we give an extended version of Combinatorial Nullstellensatz,
with weaker assumption on nonvanishing monomial. We also present an application
of our result in a situation where the original theorem does not seem to work.


title: Interface tracking using patches

abstract:
  A new method for interface tracking is presented. The interface
representation, based on domain decomposition, provides the interface location
explicitly, yet is Eulerian. This allows for well established finite difference
methods on uniform grids to be used for the numerics of advecting the interface
and other computations. CFL-stable and second order accurate explicit and
implicit time-stepping methods are derived. Numerical results are given to
substantiate stated convergence properties, as well as convergence in interface
curvature and mass conservation. Our method is applied to a boundary integral
formulation for Stokes flow, and the resulting integrals are analyzed and
treated numerically to second order accuracy. Finally, we embed our method in
the familiar immersed boundary- and immersed interface methods for two-phase
Navier-Stokes flow.


title: Discrete holomorphicity and quantized affine algebras

abstract:
  We consider non-local currents in the context of quantized affine algebras,
following the construction introduced by Bernard and Felder. In the case of
$U_q(A_1^{(1)})$ and $U_q(A_2^{(2)})$, these currents can be identified with
configurations in the six-vertex and Izergin--Korepin nineteen-vertex models.
Mapping these to their corresponding Temperley--Lieb loop models, we directly
identify non-local currents with discretely holomorphic loop observables. In
particular, we show that the bulk discrete holomorphicity relation and its
recently derived boundary analogue are equivalent to conservation laws for
non-local currents.


title: Unitary cycles on Shimura curves and the Shimura lift I

abstract:
  This paper concerns two families of divisors, which we call the `orthogonal'
and `unitary' special cycles, defined on integral models of Shimura curves. The
orthogonal family was studied extensively by Kudla-Rapoport-Yang, who showed
that they are closely related to the Fourier coefficients of modular forms of
weight 3/2, while the `unitary' divisors are analogues of cycles appearing in
more recent work of Kudla-Rapoport on unitary Shimura varieties. Our main
result shows that these two families are related by (a formal version of) the
Shimura lift.


title:
Anatomy of flavour-changing Z couplings in models with partial
  compositeness

abstract:
  In models with partially composite quarks, the couplings of quarks to the Z
boson generically receive non-universal corrections that are not only
constrained by electroweak precision tests but also lead to flavour-changing
neutral currents at tree level. The impact of these flavour-changing couplings
on rare K and B decays is studied in two-site models for three scenarios: an
anarchic strong sector with two different choices of fermion representations
both leading to a custodial protection of the Z->bb coupling, and for a strong
sector invariant under a U(2)^3 flavour symmetry. In the complete numerical
analysis, all relevant constraints from Delta(F)=2 processes are taken into
account. In all scenarios, visible effects in rare K and B decays like K->pi nu
anti-nu, B(s)->mu+mu- and B->K*mu+mu- are possible that can be scrutinized
experimentally in the near future. Characteristic correlations between
observables allow to distinguish the different cases. To sample the large
parameter space of the anarchic models, a new method is presented that allows
larger statistics than conventional approaches.


title:
Latest Constraints from Jet Measurements on Parton Distribution
  Functions and on the Strong Coupling Constant

abstract:
  Recent measurements of jet cross sections at HERA, the Tevatron and the LHC
that provide constraints on parton distribution functions and allow for
determinations of the strong coupling constant are presented.


title: Probing nonperturbative QED with optimally focused laser pulses

abstract:
  We study nonperturbative pair production in intense, focused laser fields
called e-dipole pulses. We address the conditions required, such as the quality
of the vacuum, for reaching high intensities without initiating beam-depleting
cascades, the number of pairs which can be created, and experimental detection
of the created pairs. We find that e-dipole pulses offer an optimal method of
investigating nonperturbative QED.


title: Quantum entanglement in finite-dimensional Hilbert spaces

abstract:
  In the past decades, quantum entanglement has been recognized to be the basic
resource in quantum information theory. A fundamental need is then the
understanding its qualification and its quantification: Is the quantum state
entangled, and if it is, then how much entanglement is carried by that? These
questions introduce the topics of separability criteria and entanglement
measures, both of which are based on the issue of classification of
multipartite entanglement. In this dissertation, after reviewing these three
fundamental topics for finite dimensional Hilbert spaces, I present my
contribution to knowledge. My main result is the elaboration of the partial
separability classification of mixed states of quantum systems composed of
arbitrary number of subsystems of Hilbert spaces of arbitrary dimensions. This
problem is simple for pure states, however, for mixed states it has not been
considered in full detail yet. I give not only the classification but also
necessary and sufficient criteria for the classes, which make it possible to
determine to which class a mixed state belongs. Moreover, these criteria are
given by the vanishing of quantities measuring entanglement. Apart from these,
I present some side results related to the entanglement of mixed states. These
results are obtained in the learning phase of my studies and give some
illustrations and examples.


title:
Integers in number systems with positive and negative quadratic Pisot
  base

abstract:
  We consider numeration systems with base $\beta$ and $-\beta$, for quadratic
Pisot numbers $\beta$ and focus on comparing the combinatorial structure of the
sets $\Z_\beta$ and $\Z_{-\beta}$ of numbers with integer expansion in base
$\beta$, resp. $-\beta$. Our main result is the comparison of languages of
infinite words $u_\beta$ and $u_{-\beta}$ coding the ordering of distances
between consecutive $\beta$- and $(-\beta)$-integers. It turns out that for a
class of roots $\beta$ of $x^2-mx-m$, the languages coincide, while for other
quadratic Pisot numbers the language of $u_\beta$ can be identified only with
the language of a morphic image of $u_{-\beta}$. We also study the group
structure of $(-\beta)$-integers.


title: Throughput Analysis of CSMA Wireless Networks with Finite Offered-load

abstract:
  This paper proposes an approximate method, equivalent access intensity (EAI),
for the throughput analysis of CSMA wireless networks in which links have
finite offered-load and their MAC-layer transmit buffers may be empty from time
to time. Different from prior works that mainly considered the saturated
network, we take into account in our analysis the impacts of empty transmit
buffers on the interactions and dependencies among links in the network that is
more common in practice. It is known that the empty transmit buffer incurs
extra waiting time for a link to compete for the channel airtime usage, since
when it has no packet waiting for transmission, the link will not perform
channel competition. The basic idea behind EAI is that this extra waiting time
can be mapped to an equivalent "longer" backoff countdown time for the
unsaturated link, yielding a lower link access intensity that is defined as the
mean packet transmission time divided by the mean backoff countdown time. That
is, we can compute the "equivalent access intensity" of an unsaturated link to
incorporate the effects of the empty transmit buffer on its behavior of channel
competition. Then, prior saturated ideal CSMA network (ICN) model can be
adopted for link throughput computation. Specifically, we propose an iterative
algorithm, "Compute-and-Compare", to identify which links are unsaturated under
current offered-load and protocol settings, compute their "equivalent access
intensities" and calculate link throughputs. Simulation shows that our
algorithm has high accuracy under various offered-load and protocol settings.
We believe the ability to identify unsaturated links and compute links
throughputs as established in this paper will serve an important first step
toward the design and optimization of general CSMA wireless networks with
offered-load control.


title:
Gate-tuned two-channel Kondo screening by graphene leads: Universal
  scaling of the nonlinear conductance

abstract:
  Based on the non-crossing approximation, we calculate both the linear and
nonlinear conductance within the two-lead two-channel single-impurity Anderson
model where the conduction electron density of states vanishes in a power-law
fashion $ \propto |\omega-\mu_F|^r$ with $r=1$ near the Fermi energy,
appropriate for an hexagonal system. For given gate voltage, we address the
universal crossover from a two-channel Kondo phase, argued to occur in doped
graphene, to an unscreened local moment phase. We extract universal scaling
functions in conductance governing charge transfer through the two-channel
pseudogap Kondo impurity and discuss our results in the context of a recent
scanning tunneling spectroscopy experiment on Co-doped graphene.


title: Asymmetric Langevin dynamics for the ferromagnetic spherical model

abstract:
  The present work pursues the investigation of the role of spatial asymmetry
and irreversibility on the dynamical properties of spin systems. We consider
the ferromagnetic spherical model with asymmetric linear Langevin dynamics.
Such an asymmetric dynamics is irreversible, i.e., breaks detailed balance,
because the principle of action and reaction is violated. The
fluctuation-dissipation theorem therefore no longer holds. The stationary state
is however still Gibbsian, i.e., the weights of configurations are given by the
Boltzmann factor corresponding to the ferromagnetic Hamiltonian. The model is
exactly solvable in any dimension, enabling an analytical evaluation of
time-dependent observables. We show the existence of two regimes of violation
of the fluctuation-dissipation theorem in the nonequilibrium stationary state:
a regime of weak violation where the stationary fluctuation-dissipation ratio
is finite but less than unity and varies continuously with the asymmetry, and a
regime of strong violation where the fluctuation-dissipation ratio vanishes
asymptotically. This phenomenon was first uncovered in the asymmetric kinetic
Ising chain. The present results suggest that this novel kind of dynamical
transition in nonequilibrium stationary states might be quite general. We also
perform a systematic analysis of several regimes of interest, either stationary
or transient, in various dimensions and in the different phases of the model.


title: Spatial Backfitting of Roller Measurement Values from a Florida Test Bed

abstract:
  Modern earthwork compaction rollers collect location and compaction
information as they traverse a compaction site. These data are indirectly
observed through non-linear measurement operators, inherently multivariate with
complex correlation structures, and collected in huge quantities. The nature of
such data was investigated at a large, atypically compacted test bed in
Florida, USA. Exploratory analysis of this data through detrending and
empirical semivariogram estimation is performed. A second analysis using a
sequential, spatial backfitting algorithm is used to investigate the importance
of driving direction of the roller.


title: Compressive Classification

abstract:
  This paper derives fundamental limits associated with compressive
classification of Gaussian mixture source models. In particular, we offer an
asymptotic characterization of the behavior of the (upper bound to the)
misclassification probability associated with the optimal Maximum-A-Posteriori
(MAP) classifier that depends on quantities that are dual to the concepts of
diversity gain and coding gain in multi-antenna communications. The diversity,
which is shown to determine the rate at which the probability of
misclassification decays in the low noise regime, is shown to depend on the
geometry of the source, the geometry of the measurement system and their
interplay. The measurement gain, which represents the counterpart of the coding
gain, is also shown to depend on geometrical quantities. It is argued that the
diversity order and the measurement gain also offer an optimization criterion
to perform dictionary learning for compressive classification applications.


title:
Extension property and complementation of isometric copies of continuous
  functions spaces

abstract:
  In this article we prove that every isometric copy of C(L) in C(K) is
complemented if L is compact Hausdorff of finite height and K is a compact
Hausdorff space satisfying the extension property, i.e., every closed subset of
K admits an extension operator. The space C(L) can be replaced by its subspace
C(L|F) consisting of functions that vanish on a closed subset F of L. We also
study the class of spaces having the extension property, establishing some
closure results for this class and relating it to other classes of compact
spaces.


title:
Variational Monte Carlo approach to the two-dimensional Kondo lattice
  model

abstract:
  We study the phase diagram of the Kondo-lattice model with nearest-neighbor
hopping in the square lattice by means of the variational Monte Carlo
technique. Specifically, we analyze a wide class of variational wave functions
that allow magnetic and superconducting order parameters, so to assess the
possibility that superconductivity might emerge close to the magnetic
instability, as often observed in heavy fermion systems. Indeed, we do find
evidence of d-wave superconductivity in the paramagnetic sector, i.e., when
magnetic order is not allowed in the variational wave function. However, when
magnetism is allowed, it completely covers the superconducting region, which
thus disappears from the phase diagram.


title: Directional amplification with a Josephson circuit

abstract:
  Non-reciprocal devices, which have different transmission coefficients for
propagating waves in opposite directions, are crucial components in many low
noise quantum measurements. In most schemes, magneto-optical effects provide
the necessary non-reciprocity. In contrast, the proof-of-principle device
presented here, consists of two on-chip coupled Josephson parametric converters
(JPCs), which achieves directionality by exploiting the non-reciprocal phase
response of the JPC in the trans-gain mode. The non-reciprocity of the device
is controlled in-situ by varying the amplitude and phase difference of two
independent microwave pump tones feeding the system. At the desired working
point and for a signal frequency of 8.453 GHz, the device achieves a forward
power gain of 15 dB within a dynamical bandwidth of 9 MHz, a reverse gain of -6
dB and suppression of the reflected signal by 8 dB. We also find that the
amplifier adds a noise equivalent to less than one and a half photons at the
signal frequency (referred to the input). It can process up to 3 photons at the
signal frequency per inverse dynamical bandwidth. With a directional amplifier
operating along the principles of this device, qubit and readout preamplifier
could be integrated on the same chip.


title: ADHM Polytopes

abstract:
  We discuss the construction of ADHM data for Yang-Mills instantons with the
symmetries of the regular polytopes in four dimensions. We show that the case
of the pentatope can be studied using a simple modification of the approach
previously developed for platonic data. For the remaining polytopes, we
describe a framework in which the building blocks of the ADHM data correspond
to the edges in the extended Dynkin diagram that arises via the McKay
correspondence. These building blocks are then assembled into ADHM data through
the identification of pairs of commuting representations of the associated
binary polyhedral group. We illustrate our procedure by the construction of
ADHM data associated with the pentatope, the hyperoctahedron and the 24-cell,
with instanton charges 4, 7 and 23, respectively. Furthermore, we show that
within our framework these are the lowest possible charges with these
symmetries. Plots of topological charge densities are presented that confirm
the polytope structure and the relation to JNR instanton data is clarified.


title:
Discovery of a 168.8 s X-ray pulsar transiting in front of its Be
  companion star in the Large Magellanic Cloud

abstract:
  We report the discovery of LXP169, a new high-mass X-ray binary (XRB) in the
LMC. The optical counterpart has been identified and appears to exhibit an
eclipsing light curve. We performed follow-up observations to clarify the
eclipsing nature of the system. Energy spectra and time series were extracted
from two XMM-Newton observations to search for pulsations, characterise the
spectrum, and measure spectral and timing changes. Long-term X-ray variability
was studied using archival ROSAT data. The XMM positions were used to identify
the optical counterpart. We obtained UV to NIR photometry to characterise the
companion, along with its 4000 d long I-band light curve. We observed LXP169
with Swift at two predicted eclipse times. We found a spin period of 168.8 s
that did not change between two XMM observations. The X-ray spectrum, well
characterised by a power law, was harder when the source was brighter. The
X-ray flux of LXP169 is found to be variable by a factor of at least 10. The
counterpart is highly variable on short and long timescales, and its photometry
is that of an early-type star with a NIR excess. This classifies the source as
a BeXRB pulsar. We observed a transit in the UV, thereby confirming that the
companion star itself is eclipsed. We give an ephemeris for the transit of MJD
56203.877 + N*24.329. We propose and discuss the scenario where the matter
captured from the companion's equatorial disc creates an extended region of
high density around the neutron star (NS), which partially eclipses the
companion as the NS transits in front of it. This is most likely the first time
the compact object in an XRB is observed to eclipse its companion star. LXP169
would be the first eclipsing BeXRB, and a wealth of important information might
be gained from additional observations, such as a measure of the possible Be
disc/orbital plane misalignment, or the mass of the NS.


title:
Variational approach to second-order impulsive dynamic equations on time
  scales

abstract:
  The aim of this paper is to employ variational techniques and critical point
theory to prove some conditions for the existence of solutions to nonlinear
impulsive dynamic equation with homogeneous Dirichlet boundary conditions. Also
we will be interested in the solutions of the impulsive nonlinear problem with
linear derivative dependence satisfying an impulsive condition.


title:
Equations in simple matrix groups: algebra, geometry, arithmetic,
  dynamics

abstract:
  We present a survey of results on word equations in simple groups, as well as
their analogues and generalizations, which were obtained over the past decade
using various methods, group-theoretic and coming from algebraic and arithmetic
geometry, number theory, dynamical systems and computer algebra. Our focus is
on interrelations of these machineries which led to numerous spectacular
achievements, including solutions of several long-standing problems.


title: Waiting Time Distribution for the Emergence of Superpatterns

abstract:
  Consider a sequence X_1, X_2,... of i.i.d. uniform random variables taking
values in the alphabet set {1,2,...,d}. A k-superpattern is a realization of
X_1,...,X_t that contains, as an embedded subsequence, each of the
non-order-isomorphic subpatterns of length k. We focus on the non-trivial case
of d=k=3 and study the waiting time distribution of tau=inf{t>=7: X_1,...,X_t
is a superpattern}


title:
Quantum First-Passage Time: Exact Solutions for a Class of Tight-Binding
  Hamiltonian Systems

abstract:
  The Schr\"odinger integral-equation approach for calculating the classical
first-passage time (C-fpt) probability density is extended to the case of
quantum first-passage time (Q-fpt). Using this extension, we have calculated
analytically the Q-fpt probability density for a class of few-site/state
tight-binding Hamiltonian systems, e.g., a qubit, as well as for an infinite 1D
lattice. The defining feature of such a quantum system is that the passage
across the boundary between a subspace (omega) and its complement (omega-bar)
is through a unique pair of "door-way" sites such that the first departure from
(arrival at) omega corresponds to the first arrival at (departure from)
omega-bar. The Q-fpt probability density so derived remains positive over the
time interval in which it also normalizes to unity. These conditions of
positivity and normalization define the physical time domain for the Q-fpt
problem. This time domain is found to remain finite for the few-site/state
Hamiltonian systems considered here, which is quite unlike the case for the
diffusive C-fpt problems. The door-way sites and the associated Q-fpt
probability density derived here should be relevant to
inter-biomolecular/nanostructural electron transport phenomena.


title:
Exact-Repair Regenerating Codes Via Layered Erasure Correction and Block
  Designs

abstract:
  A new class of exact-repair regenerating codes is constructed by combining
two layers of erasure correction codes together with combinatorial block
designs, e.g., Steiner systems, balanced incomplete block designs and
t-designs. The proposed codes have the "uncoded repair" property where the
nodes participating in the repair simply transfer part of the stored data
directly, without performing any computation. The layered error correction
structure makes the decoding process rather straightforward, and in general the
complexity is low. We show that this construction is able to achieve
performance better than time-sharing between the minimum storage regenerating
codes and the minimum repair-bandwidth regenerating codes.


title:
Spin-flip hot spots in ultrathin films of monovalent metals: Enhancement
  and anisotropy of the Elliott-Yafet parameter

abstract:
  In contrast to the long-known fact that spin-flip hot spots, i.e., special
\vc{k}-points on the Fermi surface showing a high spin-mixing parameter, do not
occur in the bulk of monovalent (noble and alkali) metals, we found them on the
surface Brillouin-zone boundary of ultrathin films of these metals.
Density-functional calculations within the Korringa-Kohn-Rostoker Green
function method for ultrathin (001) oriented Cu, Ag, and Au films of 10-layer
thickness show that the region around the hot spots can have a substantial
contribution, e.g.\ 52\% in Au(001), to the integrated spin-mixing parameter,
that could lead to a significant enhancement of the spin-relaxation rate or
spin-Hall angle in thin films. Owing to the appearance of spin-flip hot-spots,
a large anisotropy of the Elliott-Yafet parameter [50\% for Au(001)] is also
found in these systems. The findings are important for spintronics applications
in which noble-metals are frequently used and in which the dimensionality of
the sample is reduced.


title: Monte Carlo Sampling in Fractal Landscapes

abstract:
  We propose a flat-histogram Monte Carlo method to efficiently sample fractal
landscapes such as escape time functions of open chaotic systems. This is
achieved by using a random-walk step which depends on the height of the
landscape via the largest Lyapunov exponent of the associated chaotic system.
By generalizing the Wang-Landau algorithm, we obtain a method which
simultaneously constructs the density of states (escape time distribution) and
the correct step-length distribution. As a result, averages are obtained in
polynomial computational time, a dramatic improvement over the exponential
scaling of traditional uniform sampling. Our results are not limited by the
dimensionality of the phase space and are confirmed numerically for dimensions
as large as 30.


title: Good Recognition is Non-Metric

abstract:
  Recognition is the fundamental task of visual cognition, yet how to formalize
the general recognition problem for computer vision remains an open issue. The
problem is sometimes reduced to the simplest case of recognizing matching
pairs, often structured to allow for metric constraints. However, visual
recognition is broader than just pair matching -- especially when we consider
multi-class training data and large sets of features in a learning context.
What we learn and how we learn it has important implications for effective
algorithms. In this paper, we reconsider the assumption of recognition as a
pair matching test, and introduce a new formal definition that captures the
broader context of the problem. Through a meta-analysis and an experimental
assessment of the top algorithms on popular data sets, we gain a sense of how
often metric properties are violated by good recognition algorithms. By
studying these violations, useful insights come to light: we make the case that
locally metric algorithms should leverage outside information to solve the
general recognition problem.


title:
Brownian diode: Molecular motor based on a semi-permeable Brownian
  particle with internal potential drop

abstract:
  A model of an autonomous isothermal Brownian motor with an internal
propulsion mechanism is considered. The motor is a Brownian particle which is
semi-transparent for molecules of surrounding ideal gas. Molecular passage
through the particle is controlled by a potential similar to that in the
transition rate theory, i.e. characterized by two stationary states with a
finite energy difference separated by a potential barrier. The internal
potential drop maintains the diode-like asymmetry of molecular fluxes through
the particle, which results in the particle's stationary drift.


title: Optical spin orientation and depolarization in Ge

abstract:
  Optical spin orientation and depolarization phenomena in semiconductors are
of overwhelming importance for the development of spin-optoelectronics. In this
paper we employ Ge-based spin-photodiodes to investigate the room temperature
spectral dependence of optical spin orientation in Germanium, in the range
400-1550 nm, and the photo-carrier spin relaxation phenomena. Apart from the
maximum in the spin polarization of photo-carriers for photon energy resonant
with the direct gap (1550 nm), we experimentally demonstrate the presence of a
second sizable peak at 530 nm due to photo-generation far away from the center
of the Brillouin zone, within the L valleys. Furthermore, our data indicate
that the equivalent the spin lifetime of holes in Ge is in the order of 5-10
ps, meaning that the spin diffusion length for holes at room temperature is
larger than expected, in the order of 150-220 nm.


title:
Analysis of multilevel Monte Carlo path simulation using the Milstein
  discretisation

abstract:
  The multilevel Monte Carlo path simulation method introduced by Giles ({\it
Operations Research}, 56(3):607-617, 2008) exploits strong convergence
properties to improve the computational complexity by combining simulations
with different levels of resolution. In this paper we analyse its efficiency
when using the Milstein discretisation; this has an improved order of strong
convergence compared to the standard Euler-Maruyama method, and it is proved
that this leads to an improved order of convergence of the variance of the
multilevel estimator. Numerical results are also given for basket options to
illustrate the relevance of the analysis.


title: Domination in transitive colorings of tournaments

abstract:
  An edge coloring of a tournament $T$ with colors $1,2,\dots,k$ is called \it
$k$-transitive \rm if the digraph $T(i)$ defined by the edges of color $i$ is
transitively oriented for each $1\le i \le k$. We explore a conjecture of the
second author: For each positive integer $k$ there exists a (least) $p(k)$ such
that every $k$-transitive tournament has a dominating set of at most $p(k)$
vertices.
  We show how this conjecture relates to other conjectures and results. For
example, it is a special case of a well-known conjecture of Erd\H os, Sands,
Sauer and Woodrow (so the conjecture is interesting even if false). We show
that the conjecture implies a stronger conjecture, a possible extension of a
result of B\'ar\'any and Lehel on covering point sets by boxes. The principle
used leads also to an upper bound $O(2^{2^{d-1}}d\log d)$ on the
$d$-dimensional box-cover number that is better than all previous bounds, in a
sense close to best possible. We also improve the best bound known in
3-dimensions from $3^{14}$ to 64 and propose possible further improvements
through finding the maximum domination number over parity tournaments.


title:
On the Radio Polarization Signature of Efficient and Inefficient
  Particle Acceleration in Supernova Remnant SN 1006

abstract:
  We present a radio polarization study of SN 1006, based on combined VLA and
ATCA observations at 20 cm that resulted in sensitive images with an angular
resolution of 10 arcsec. The fractional polarization in the two bright radio
and X-ray lobes of the SNR is measured to be 0.17, while in the southeastern
sector, where the radio and non-thermal X-ray emission are much weaker, the
polarization fraction reaches a value of 0.6 +- 0.2, close to the theoretical
limit of 0.7. We interpret this result as evidence of a disordered, turbulent
magnetic field in the lobes, where particle acceleration is believed to be
efficient, and a highly ordered field in the southeast, where the acceleration
efficiency has been shown to be very low. Utilizing the frequency coverage of
our observations, an average rotation measure of ~12 rad/m2 is determined from
the combined data set, which is then used to obtain the intrinsic direction of
the magnetic field vectors. While the orientation of magnetic field vectors
across the SNR shell appear radial, a large fraction of the magnetic vectors
lie parallel to the Galactic Plane. Along the highly polarized southeastern
rim, the field is aligned tangent to the shock, and therefore also nearly
parallel to the Galactic Plane. These results strongly suggest that the ambient
field surrounding SN 1006 is aligned with this direction (i.e., from northeast
to southwest) and that the bright lobes are due to a polar cap geometry. Our
study establishes that the most efficient particle acceleration and generation
of magnetic turbulence in SN 1006 is attained for shocks in which the magnetic
field direction and shock normal are quasi-parallel, while inefficient
acceleration and little to no generation of magnetic turbulence obtains for the
quasi-perpendicular case.


title: Rationalizing Investors Choice

abstract:
  Assuming that agents' preferences satisfy first-order stochastic dominance,
we show how the Expected Utility paradigm can rationalize all optimal
investment choices: the optimal investment strategy in any behavioral
law-invariant (state-independent) setting corresponds to the optimum for an
expected utility maximizer with an explicitly derived concave non-decreasing
utility function. This result enables us to infer the utility and risk aversion
of agents from their investment choice in a non-parametric way. We relate the
property of decreasing absolute risk aversion (DARA) to distributional
properties of the terminal wealth and of the financial market. Specifically, we
show that DARA is equivalent to a demand for a terminal wealth that has more
spread than the opposite of the log pricing kernel at the investment horizon.


title:
Moving target inference with hierarchical Bayesian models in synthetic
  aperture radar imagery

abstract:
  In synthetic aperture radar (SAR), images are formed by focusing the response
of stationary objects to a single spatial location. On the other hand, moving
targets cause phase errors in the standard formation of SAR images that cause
displacement and defocusing effects. SAR imagery also contains significant
sources of non-stationary spatially-varying noises, including antenna gain
discrepancies, angular scintillation (glints) and complex speckle. In order to
account for this intricate phenomenology, this work combines the knowledge of
the physical, kinematic, and statistical properties of SAR imaging into a
single unified Bayesian structure that simultaneously (a) estimates the
nuisance parameters such as clutter distributions and antenna miscalibrations
and (b) estimates the target signature required for detection/inference of the
target state. Moreover, we provide a Monte Carlo estimate of the posterior
distribution for the target state and nuisance parameters that infers the
parameters of the model directly from the data, largely eliminating tuning of
algorithm parameters. We demonstrate that our algorithm competes at least as
well on a synthetic dataset as state-of-the-art algorithms for estimating
sparse signals. Finally, performance analysis on a measured dataset
demonstrates that the proposed algorithm is robust at detecting/estimating
targets over a wide area and performs at least as well as popular algorithms
for SAR moving target detection.


title: Leavitt path algebras which are Zorn rings

abstract:
  Let E be an arbitrary directed graph and let K be any field. It is shown that
the Leavitt path algebra A of the graph E over the field K is a Zorn ring if
and only if the graph E satisfies the Condition (L), that is, every cycle in E
has an exit. It is also shown that the Leavitt path algebra A is a weakly
regular ring if and only if every homomorphic image of A is a Zorn ring. The
corresponding statement for graph C*-algebras is also investigated.


title:
Ion-neutral chemistry at ultralow energies: Dynamics of reactive
  collisions between laser-cooled Ca^+ ions and Rb atoms in an ion-atom hybrid
  trap

abstract:
  Cold chemical reactions between laser-cooled Ca^+ ions and Rb atoms were
studied in an ion-atom hybrid trap. Reaction rate constants were determined in
the range of collision energies <E_{coll}>/k_B = 20 mK-20 K. The lowest
energies were achieved in experiments using single localized Ca^+ ions. Product
branching ratios were studied using resonant-excitation mass spectrometry. The
dynamics of the reactive processes in this system (non-radiative and radiative
charge transfer as well as radiative association leading to the formation of
CaRb^+ molecular ions) have been analyzed using high-level quantum-chemical
calculations of the potential energy curves of CaRb^+ and quantum-scattering
calculations for the radiative channels. For the present low-energy scattering
experiments, it is shown that the energy dependence of the reaction rate
constants is governed by long-range interactions in line with the classical
Langevin model, but their magnitude is determined by short-range non-adiabatic
and radiative couplings which only weakly depend on the asymptotic energy. The
quantum character of the collisions is predicted to manifest itself in the
occurrence of narrow shape resonances at well-defined collision energies. The
present results highlight both universal and system-specific phenomena in cold
ion-neutral reactive collisions.


title:
From non-semisimple Hopf algebras to correlation functions for
  logarithmic CFT

abstract:
  We use factorizable finite tensor categories, and specifically the
representation categories of factorizable ribbon Hopf algebras H, as a
laboratory for exploring bulk correlation functions in local logarithmic
conformal field theories. For any ribbon Hopf algebra automorphism omega of H
we present a candidate for the space of bulk fields and endow it with a natural
structure of a commutative symmetric Frobenius algebra. We derive an expression
for the corresponding bulk partition functions as bilinear combinations of
irreducible characters; as a crucial ingredient this involves the Cartan matrix
of the category. We also show how for any candidate bulk state space of the
type we consider, correlation functions of bulk fields for closed oriented
world sheets of any genus can be constructed that are invariant under the
natural action of the relevant mapping class group.


title: Polarimetric observations of $\sigma$ Orionis E

abstract:
  Some massive stars possess strong magnetic fields that confine plasma in the
circumstellar environment. These \textit{magnetospheres} have been studied
spectroscopically, photometrically and, more recently, interferometrically.
Here we report on the first firm detection of a magnetosphere in continuum
linear polarization, as a result of monitoring of $\sigma$\,Ori\,E at the Pico
dos Dias Observatory. {The non-zero intrinsic polarization indicates an
asymmetric structure, whose minor elongation axis is oriented $150\fdg0$ east
of the celestial north.} A modulation of the polarization was observed, with a
period of half of the rotation period, which supports the theoretical
prediction of the presence of two diametrally opposed, co-rotating blobs of
gas. A phase lag of -0.085 was detected between the polarization minimum and
the primary minimum of the light curve, suggestive of a complex shape of the
plasma clouds. We present a preliminary analysis of the data with the Rigidly
Rotating Magnetosphere model, which could not reproduce simultaneously the
photometric and polarimetric data. A toy model comprising two spherical
co-rotating blobs {joined by a thin disk} proved more successful in reproducing
the polarization modulation. {With this model we were able to determine that
the total scattering mass of the thin disk is similar to the mass of the blobs
($2M_{\rm b}/M_{\rm d}=1.2$) and that the blobs are rotating counterclockwise
on the plane of the sky.} This result shows that polarimetry can provide a
diagnostic of the geometry of clouds, which will serve as an important
constraint for {improving} the Rigidly Rotating Magnetosphere model.


title: A new critical curve for the Lane-Emden system

abstract:
  We study stable positive radially symmetric solutions for the Lane-Emden
system $-\Delta u=v^p$ in $\R^N$, $-\Delta v=u^q$ in $\R^N$, where $p,q\geq 1$.
We obtain a new critical curve that optimally describes the existence of such
solutions.


title: Categorification of the Heisenberg algebra and MacMahon function

abstract:
  Starting from a one dimensional vector space, we construct a categorification
$'\mathcal H$ of a deformed Heiserberg algebra $'H$ by Cautis and Licata's
method. The Grothendieck ring of $'\mathcal H$ is $'H$. As an application, we
discuss some related partition functions related to the MacMahon function of 3D
Young diagram. We expect further applications of the results of this paper.


title:
Stabilizing fractional vortices in multiband superconductors with
  periodic pinning arrays

abstract:
  Multiband superconductors support the excitation of vortices with fractional
quantum flux, known as fractional vortices. In the ground state, the fractional
vortices in different bands bond together to form a composite vortex with the
standard flux quantum $\Phi_0$; thus, it is difficult to stabilize the
fractional vortices. Here we show that fractional vortex lattices can be
stabilized in multiband superconductors with a periodic pinning array at the
half matching field of the composite system, when full matching of the
fractionalized vortices occurs. In the presence of a high current, the
fractional vortices in different bands decouple and move at different
velocities. When the current is turned off suddenly, the fractional vortices in
different bands may be trapped at different pinning sites. This system also
exhibits rich dynamic behavior, and for fractional vortices in two-band
superconductors we find a phases where the vortices one band are pinned and the
vortices in the other band are moving. These different phases can be observed
in transport measurements, and produce a new type of self-induced Shapiro steps
that can arise under the application of only a dc drive.


title:
An Algorithm for Computing the Limit Points of the Quasi-component of a
  Regular Chain

abstract:
  For a regular chain $R$, we propose an algorithm which computes the
(non-trivial) limit points of the quasi-component of $R$, that is, the set
$\bar{W(R)} \setminus W(R)$. Our procedure relies on Puiseux series expansions
and does not require to compute a system of generators of the saturated ideal
of $R$. We focus on the case where this saturated ideal has dimension one and
we discuss extensions of this work in higher dimensions. We provide
experimental results illustrating the benefits of our algorithms.


title:
An Approach to Select Cost-Effective Risk Countermeasures Exemplified in
  CORAS

abstract:
  Risk is unavoidable in business and risk management is needed amongst others
to set up good security policies. Once the risks are evaluated, the next step
is to decide how they should be treated. This involves managers making
decisions on proper countermeasures to be implemented to mitigate the risks.
The countermeasure expenditure, together with its ability to mitigate risks, is
factors that affect the selection. While many approaches have been proposed to
perform risk analysis, there has been less focus on delivering the prescriptive
and specific information that managers require to select cost-effective
countermeasures. This paper proposes a generic approach to integrate the cost
assessment into risk analysis to aid such decision making. The approach makes
use of a risk model which has been annotated with potential countermeasures,
estimates for their cost and effect. A calculus is then employed to reason
about this model in order to support decision in terms of decision diagrams. We
exemplify the instantiation of the generic approach in the CORAS method for
security risk analysis.


title: Optimal coherent control to counteract dissipation

abstract:
  We study to what extent the detrimental impact of dissipation on quantum
properties can be compensated by suitable coherent dynamics. To this end, we
develop a general method to determine the control Hamiltonian that optimally
counteracts a given dissipation mechanism, in order to sustain the desired
property, and apply it to two exemplary target properties: the coherence of a
decaying two-level system, and the entanglement of two qubits in the presence
of local dissipation.


title:
Ab Initio Equation of State for Hydrogen-Helium Mixtures with
  Recalibration of the Giant-Planet Mass-Radius Relation

abstract:
  Using density functional molecular dynamics simulations, we determine the
equation of state for hydrogen-helium mixtures spanning density-temperature
conditions typical of giant planet interiors, ~0.2-9 g/cc and 1000-80000 K for
a typical helium mass fraction of 0.245. In addition to computing internal
energy and pressure, we determine the entropy using an ab initio thermodynamic
integration technique. A comprehensive equation of state (EOS) table with 391
density-temperature points is constructed and the results are presented in form
of two-dimensional free energy fit for interpolation. Deviations between our ab
initio EOS and the semi-analytical EOS model by Saumon and Chabrier are
analyzed in detail, and we use the results for initial revision of the inferred
thermal state of giant planets with known values for mass and radius. Changes
are most pronounced for planets in the Jupiter mass range and below. We present
a revision to the mass-radius relationship which makes the hottest exoplanets
increase in radius by ~0.2 Jupiter radii at fixed entropy and for masses
greater than ~0.5 Jupiter mass. This change is large enough to have possible
implications for some discrepant "inflated giant exoplanets".


title: On the intersection form of surfaces

abstract:
  Given a closed, oriented surface M, the algebraic intersection of closed
curves induces a symplectic form Int(.,.) on the first homology group of M. If
M is equipped with a Riemannian metric g, the first homology group of M
inherits a norm, called the stable norm. We study the norm of the bilinear form
Int(.,.), with respect to the stable norm.


title:
Virtual in situs: Sequencing mRNA from cryo-sliced Drosophila embryos to
  determine genome-wide spatial patterns of gene expression

abstract:
  Complex spatial and temporal patterns of gene expression underlie embryo
differentiation, yet methods do not yet exist for the efficient genome-wide
determination of spatial expression patterns during development. In situ
imaging of transcripts and proteins is the gold-standard, but it is difficult
and time consuming to apply to an entire genome, even when highly automated.
Sequencing, in contrast, is fast and genome-wide, but is generally applied to
homogenized tissues, thereby discarding spatial information. It is likely that
these methods will ultimately converge, and we will be able to sequence RNAs in
situ, simultaneously determining their identity and location. As a step along
this path, we developed methods to cryosection individual blastoderm stage
Drosophila melanogaster embryos along the anterior-posterior axis and sequence
the mRNA isolated from each 25 micron slice. The spatial patterns of gene
expression we infer closely match patterns previously determined by in situ
hybridization and microscopy. We applied this method to generate a genome-wide
timecourse of spatial gene expression from shortly after fertilization through
gastrulation. We identify numerous genes with spatial patterns that have not
yet been described in the several ongoing systematic in situ based projects.
This simple experiment demonstrates the potential for combining careful
anatomical dissection with high-throughput sequencing to obtain spatially
resolved gene expression on a genome-wide scale.


title: Dually weighted Stirling-type sequences

abstract:
  We introduce a generalization of the Stirling numbers via symmetric functions
involving two weight functions. The resulting extension unifies previously
known Stirling-type sequences with known symmetric function forms, as well as
other sequences such as the $p,q$-binomial coefficients. Recurrence relations,
generating functions, orthogonality relations, convolution formulas, and
determinants of certain matrices involving the obtained sequences are derived.
We also give combinatorial interpretations of certain cases in terms of colored
partitions and permutations.


title: Remarks on the Afriat's theorem and the Monge-Kantorovich problem

abstract:
  The famous Afriat's theorem from the theory of revealed preferences
establishes necessary and suffient conditions for existence of utility function
for a given set of choices and prices. The result on existence of a {\it
homogeneous} utility function can be considered as a particular fact of the
Monge-Kantorovich mass transportation theory. In this paper we explain this
viewpoint and discuss some related questions.


title:
Electrostatic considerations affecting the calculated HOMO-LUMO gap in
  protein molecules

abstract:
  A detailed study of energy differences between the highest occupied and
lowest unoccupied molecular orbitals (HOMO-LUMO gaps) in protein systems and
water clusters is presented. Recent work questioning the applicability of
Kohn-Sham density-functional theory to proteins and large water clusters (E.
Rudberg, J. Phys.: Condens. Mat. 2012, 24, 072202) has demonstrated vanishing
HOMO-LUMO gaps for these systems, which is generally attributed to the
treatment of exchange in the functional used. The present work shows that the
vanishing gap is, in fact, an electrostatic artefact of the method used to
prepare the system. Practical solutions for ensuring the gap is maintained when
the system size is increased are demonstrated. This work has important
implications for the use of large-scale density-functional theory in
biomolecular systems, particularly in the simulation of photoemission, optical
absorption and electronic transport, all of which depend critically on
differences between energies of molecular orbitals.


title: Multimode optical fiber based spectrometers

abstract:
  A standard multimode optical fiber can be used as a general purpose
spectrometer after calibrating the wavelength dependent speckle patterns
produced by interference between the guided modes of the fiber. A transmission
matrix was used to store the calibration data and a robust algorithm was
developed to reconstruct an arbitrary input spectrum in the presence of
experimental noise. We demonstrate that a 20 meter long fiber can resolve two
laser lines separated by only 8 pm. At the other extreme, we show that a 2
centimeter long fiber can measure a broadband continuous spectrum generated
from a supercontinuum source. We investigate the effect of the fiber geometry
on the spectral resolution and bandwidth, and also discuss the additional
limitation on the bandwidth imposed by speckle contrast reduction when
measuring dense spectra. Finally, we demonstrate a method to reduce the
spectrum reconstruction error and increase the bandwidth by separately imaging
the speckle patterns of orthogonal polarizations. The multimode fiber
spectrometer is compact, lightweight, low cost, and provides high resolution
with low loss.


title:
Interaction of a Contact Resonance of Microspheres with Surface Acoustic
  Waves

abstract:
  We study the interaction of surface acoustic waves (SAWs) with the
contact-based, axial vibrational resonance of 1 \mu m silica microspheres
forming a two-dimensional granular crystal adhered to a substrate. The
laser-induced transient grating technique is used to excite SAWs and measure
their dispersion. The measured dispersion curves exhibit "avoided crossing"
behavior due to the hybridization of the SAWs with the microsphere resonance.
We compare the measured dispersion curves with those predicted by our
analytical model, and find excellent agreement. The approach presented can be
used to study the contact mechanics and adhesion of micro- and nanoparticles as
well as the dynamics of microscale granular crystals.


title: Slater-Pauling behavior in half-metallic magnets

abstract:
  We review the appearance of Slater-Pauling rules in half-metallic magnets.
These rules have been derived using ab-initio electronic structure calculations
and directly connect the electronic properties (existence of minority-spin
energy gap) to the magnetic properties (total spin magnetic moment) in these
compounds. Their exact formulation depends on the half-metallic family under
study and they can be easily derived if the hybridization of the orbitals at
various sites is taken into account.


title:
Operational Interpretation of the Ratio of Total Correlations to
  Classical Correlations

abstract:
  We will discuss the generalization of entropic uncertainty principles in
terms of a game. The game involves k-players, each measuring one of k possible
observables. The question is, what is the maximum number of players that can
play such that their joint entropic uncertainties are tightened by the presence
of non-classical correlations? We answer this question and relate it to the
ratio of quantum mutual information to classical correlations. This game hence
serves to construct an operational interpretation of the aforementioned ratio.
It provides another example of quantum correlations providing a quantum
advantage.


title: A Receiver-Centric OFCDM Approach with Subcarrier Grouping

abstract:
  In this letter, following a cross-layer design concept, we propose a novel
subcarrier grouping technique for Orthogonal Frequency and Code Division
Multiplexing (OFCDM) multiuser systems. We adopt a two dimensional (2D)
spreading, so as to achieve both frequency- and time-domain channel gain.
Furthermore, we enable a receiver-centric approach, where the receiver rather
than a potential sender controls the admission decision of the communication
establishment. We study the robustness of the proposed scheme in terms of the
Bit-Error-Rate (BER) and the outage probability. The derived results indicate
that the proposed scheme outperforms the classical OFCDM approach.


title: Preserving first integrals with symmetric Lie group methods

abstract:
  The discrete gradient approach is generalized to yield integral preserving
methods for differential equations in Lie groups.


title: Partitions of AG(4,3) into Maximal Caps

abstract:
  In a geometry, a maximal cap is a collection of points of largest size
containing no lines. In AG(4,3), maximal caps contain 20 points. The 81 points
of AG(4,3) can be partitioned into 4 mutually disjoint maximal caps together
with a single point P, where every pair of points that makes a line with P lies
entirely inside one of those caps. The caps in a partition can be paired up so
that both pairs are either in exactly one partition or they are both in two
different partitions. This difference determines the two equivalence classes of
partitions of AG(4,3) under the action by affine transformations.


title: Giant Casimir effect in fluids in non-equilibrium steady states

abstract:
  In this letter we consider the fluctuation induced force exerted between two
plates separated by a distance $L$ in a fluid with a temperature gradient. We
predict that, for a range of distances $L$, this non-equilibrium force is
anomalously large compared to other Casimir forces. The physical reason is that
correlations in a non-equilibrium fluid are generally of longer range than
other correlations, even than those near an equilibrium critical point. This
giant Casimir force is related to a divergent Burnett coefficient that
characterizes an Onsager cross effect between the pressure and the temperature
gradient. The predicted Casimir force should be detectable with currently
available experimental techniques.


title:
Performance Analysis of the Ordered V-BLAST Approach over Nakagami-m
  Fading Channels

abstract:
  The performance of the V-BLAST approach, which utilizes successive
interference cancellation (SIC) with optimal ordering, over independent
Nakagami-m fading channels is studied. Systems with two transmit and n receive
antennas are employed whereas the potential erroneous decision of SIC is also
considered. In particular, tight closed-form bound expressions are derived in
terms of the average symbol error rate (ASER) and the outage probability, in
case of binary and rectangular M-ary constellation alphabets. The mathematical
analysis is accompanied with selected performance evaluation and numerical
results, which demonstrate the usefulness of the proposed approach.


title: Curves on Flat Tori and Analog Source-Channel Codes

abstract:
  In this paper we consider the problem of transmitting a continuous alphabet
discrete-time source over an AWGN channel. We propose a constructive scheme
based on a set of curves on the surface of a N-dimensional sphere. Our approach
shows that the design of good codes for this communication problem is related
to geometrical properties of spherical codes and projections of N-dimensional
rectangular lattices. Theoretical comparisons with some previous works in terms
of the mean square error as a function of the channel SNR as well as
simulations are provided.


title: On the Complexity of Barrier Resilience for Fat Regions

abstract:
  In the \emph {barrier resilience} problem (introduced by Kumar {\em et al.},
Wireless Networks 2007), we are given a collection of regions of the plane,
acting as obstacles, and we would like to remove the minimum number of regions
so that two fixed points can be connected without crossing any region. In this
paper, we show that the problem is NP-hard when the collection only contains
fat regions with bounded ply $\Delta$ (even when they are axis-aligned
rectangles of aspect ratio $1 : (1 + \varepsilon)$). We also show that the
problem is fixed-parameter tractable (FPT) for unit disks and for
similarly-sized $\beta$-fat regions with bounded ply $\Delta$ and $O(1)$
pairwise boundary intersections. Furthermore, we can use our FPT algorithm to
construct an $(1+\varepsilon)$-approximation algorithm that runs in
$O(2^{f(\Delta, \varepsilon,\beta)}n^5)$ time, where $f\in
O(\frac{\Delta^4\beta^8}{\varepsilon^4}\log(\beta\Delta/\varepsilon))$.


title:
Phase-resolved ultraviolet spectroscopy of the magnetic Of?p star HD
  191612

abstract:
  We present for the first time phase-resolved UV spectroscopy of an Of?p star,
namely, HD 191612. The observations were acquired with the Space Telescope
Imaging Spectrograph (STIS) on-board the Hubble Space Telescope (HST). We
report the variability observed in the main photospheric and wind features and
compare the results with previous findings for the Of?p star HD 108. We show
that UV line strengths, H(alpha), and longitudinal magnetic field, vary
coherently according to the rotational period (P = 537.6d), providing
additional support for the magnetic oblique rotator scenario. The stellar and
wind parameters of HD 191612 are obtained based on NLTE expanding atmosphere
models. The peculiar wind line profile variations revealed by the new STIS data
- not reproduced by 1D atmosphere models - are addressed through non-spherical
MHD simulations coupled with radiative transfer. The basic aspects of the UV
variability observed are explained and the structure of the dynamical
magnetosphere of HD 191612 is discussed.


title:
Inhibition of the dynamical Casimir effect with Robin boundary
  conditions

abstract:
  We consider a real massless scalar field in 3+1 dimensions satisfying a Robin
boundary condition at a nonrelativistic moving mirror. Considering vacuum as
the initial field state, we compute explicitly the number of particles created
per unit frequency and per unit solid angle, exhibiting in this way the angular
dependence of the spectral distribution. The well known cases of Dirichlet and
Neumann boundary conditions may be reobtained as particular cases from our
results. We show that the particle creation rate can be considerably reduced
(with respect to the Dirichlet and Neumann cases) for particular values of the
Robin parameter. Our results extend for 3+1 dimensions previous results found
in the literature for 1+1 dimensions. Further, we also show that this
inhibition of the dynamical Casimir effect occurs for different angles of
particle emission.


title: Excimers He2* as Tracers of Quantum Turbulence in 4He in the T=0 Limit

abstract:
  We have studied the interaction of metastable $^4$He$_2^*$ excimer molecules
with quantized vortices in superfluid $^4$He in the zero temperature limit. The
vortices were generated by either rotation or ion injection. The trapping
diameter of the molecules on quantized vortices was found to be $96\pm6$\,nm at
a pressure of 0.1\,bar and $27\pm5$\,nm at 5.0 bar. We have also demonstrated
that a moving tangle of vortices can carry the molecules through the superfluid
helium.


title:
Real and complex order integrals and derivatives operators over the set
  of causal functions

abstract:
  The fractional integrals and fractional derivatives problem is tackled by
using the operator approach. The definition domain E of operators is causal
functions.Many properties of fractional integrals are given. Fractional
derivatives definition is derived from fractional integrals one. Then an
unified definition of fractional integrals and derivatives operator is obtained
according to the sign of the real part of the order s. The study utilizes many
properties of the Euler's gamma and beta functions and their extensions in R
and C. Comparison with the definitions given by other authors (Liouville,
Riemann,Liouville-Caputo)is done too.


title:
Asymptotic expressions of eigenvalues and eigenfunctions of a
  discontinuous boundary value problem with retarded argument which contains a
  spectral parameter in the boundary conditon

abstract:
  The aim of this study is to find asymptotic expressions of eigenvalues and
eigenfunctions of a discontinuous boundary-value problem with retarded argument
which contains a spectral parameter in the boundary condition. Applications of
differential equations with retarded argument can be encountered in the theory
of selfoscillatory systems, in the study of problems connected with combustion
in rocket engines, in a number of problems in economics, biophysics, and many
other fields. The problems in these areas can be solved reducing differential
equations with retarded argument. In this study discontinuous boundary-value
problem with retarded argument which contains a spectral parameter in the
boundary condition were investigated and asymptotic formulas were obtained for
eigenvalues and eigenfunctions for using areas which mentioned above


title: Constrained Signaling in Auction Design

abstract:
  We consider the problem of an auctioneer who faces the task of selling a good
(drawn from a known distribution) to a set of buyers, when the auctioneer does
not have the capacity to describe to the buyers the exact identity of the good
that he is selling. Instead, he must come up with a constrained signalling
scheme: a (non injective) mapping from goods to signals, that satisfies the
constraints of his setting. For example, the auctioneer may be able to
communicate only a bounded length message for each good, or he might be legally
constrained in how he can advertise the item being sold. Each candidate
signaling scheme induces an incomplete-information game among the buyers, and
the goal of the auctioneer is to choose the signaling scheme and accompanying
auction format that optimizes welfare. In this paper, we use techniques from
submodular function maximization and no-regret learning to give algorithms for
computing constrained signaling schemes for a variety of constrained signaling
problems.


title: Application of difference sequences theory

abstract:
  The results of difference sequences theory are applied to analytic function
theory and Diophantine equations. As a result we have the equation which
connects the $n$-th derivative of a function with the difference sequence for
the values of this function. Also the results of difference sequences theory
helps to discover some features of the whole kind of Diophantine equations. The
method presented allows to find limits where Diophantine equation does not have
integer solutions. The higher power of Diophantine equation the better this
method works.


title: Almost sure convergence of products of $2\times2$ nonnegative matrices

abstract:
  We study the almost sure convergence of the normalized columns in an infinite
product of nonnegative matrices, and the almost sure rank one property of its
limit points. Given a probability on the set of $2\times2$ nonnegative
matrices, with finite support $\mathcal A=\{A(0),\dots,A(s-1)\}$, and assuming
that at least one of the $A(k)$ is not diagonal, the normalized columns of the
product matrix $P_n=A(\omega_1)\dots A(\omega_n)$ converge almost surely (for
the product probability) with an exponential rate of convergence if and only if
the Lyapunov exponents are almost surely distinct. If this condition is
satisfied, given a nonnegative column vector $V$ the column vector
$\frac{P_nV}{\Vert P_nV\Vert}$ also converges almost surely with an exponential
rate of convergence. On the other hand if we assume only that at least one of
the $A(k)$ do not have the form $\begin{pmatrix}a&0\\0&d\end{pmatrix}$,
$ad\ne0$, nor the form $\begin{pmatrix}0&b\\d&0\end{pmatrix}$, $bc\ne0$, the
limit-points of the normalized product matrix $\frac{P_n}{\Vert P_n\Vert}$ have
almost surely rank 1 -although the limits of the normalized columns can be
distinct- and $\frac{P_nV}{\Vert P_nV\Vert}$ converges almost surely with a
rate of convergence that can be exponential or not exponential.


title: Reduction theorem for lattice cohomology

abstract:
  The lattice cohomology of a plumbed 3--manifold $M$ associated with a
connected negative definite plumbing graph is an important tool in the study of
topological properties of $M$, and in the comparison of the topological
properties with analytic ones when $M$ is realized as complex analytic
singularity link. By definition, its computation is based on the
(Riemann--Roch) weights of the lattice points of $\Z^s$, where $s$ is the
number of vertices of the plumbing graph. The present article reduces the rank
of this lattice to the number of `bad' vertices of the graph. (Usually the
geometry/topology of $M$ is codified exactly by these `bad' vertices via
surgery or other constructions. Their number measures how far is the plumbing
graph from a rational one.) The effect of the reduction appears also at the
level of certain multivariable (topological Poincar\'e) series as well. Since
from these series one can also read the Seiberg--Witten invariants, the
reduction theorem provides new formulae for these invariants too. The reduction
also implies the vanishing $\bH^q=0$ of the lattice cohomology for $q\geq \nu$,
where $\nu$ is the number of `bad' vertices. (This bound is sharp.)


title:
Channel Sounding Waveforms Design for Asynchronous Multiuser MIMO
  Systems

abstract:
  In this paper we provide three contributions to the field of channel sounding
waveform design in asynchronous Multi-user (MU) MIMO systems. The first
contribution is a derivation of the asynchronous MU-MIMO model and the
conditions that the sounding waveform must meet to independently resolve all of
the spatial channel responses. Next we propose a chirp waveform that meets the
constraints and we show that the MSE of our system meets the Cramer-Rao Bound
(CRB) when the time offset is an integer multiple of the sampling interval.
Finally we demonstrate that the channel capacity region of the asynchronous
system and synchronous system is equivalent under certain conditions.
Simulation results are provided to illustrate the findings.


title:
Optimal Polynomial Admissible Meshes on Some Classes of Compact Subsets
  of $\R^d$

abstract:
  We show that any compact subset of $\R^d$ which is the closure of a bounded
star-shaped Lipschitz domain $\Omega$, such that $\complement \Omega$ has
positive reach in the sense of Federer, admits an \emph{optimal AM} (admissible
mesh), that is a sequence of polynomial norming sets with optimal cardinality.
This extends a recent result of A. Kro\'o on $\mathscr C^ 2$ star-shaped
domains.
  Moreover, we prove constructively the existence of an optimal AM for any $K
:= \overline\Omega \subset \R^ d$ where $\Omega$ is a bounded $\mathscr C^{
1,1}$ domain. This is done by a particular multivariate sharp version of the
Bernstein Inequality via the distance function.


title: Stability and anyonic behavior of systems with M-statistics

abstract:
  Starting with the partition function $Z$ for systems with $M$-statistics, as
proposed in \cite{WND}, we calculate from the metric
$g_{\alpha\eta}=\frac{\partial \ln Z}{\partial\beta^{\alpha}\beta^{\eta}}$ the
scalar curvature $R$ in two and three dimensions. Our results exhibit the
details of the anyonic behavior as a function of the fugacity $z$ and the
identical particle maximum occupancy number $M$. We also compare the stability
of systems for $M>1$with the fermionic (M=1), and bosonic ($M\rightarrow
\infty$), cases.


title: Multiple Target Tracking with RF Sensor Networks

abstract:
  RF sensor networks are wireless networks that can localize and track people
(or targets) without needing them to carry or wear any electronic device. They
use the change in the received signal strength (RSS) of the links due to the
movements of people to infer their locations. In this paper, we consider
real-time multiple target tracking with RF sensor networks. We perform radio
tomographic imaging (RTI), which generates images of the change in the
propagation field, as if they were frames of a video. Our RTI method uses RSS
measurements on multiple frequency channels on each link, combining them with a
fade level-based weighted average. We describe methods to adapt machine vision
methods to the peculiarities of RTI to enable real time multiple target
tracking. Several tests are performed in an open environment, a one-bedroom
apartment, and a cluttered office environment. The results demonstrate that the
system is capable of accurately tracking in real-time up to 4 targets in
cluttered indoor environments, even when their trajectories intersect multiple
times, without mis-estimating the number of targets found in the monitored
area. The highest average tracking error measured in the tests is 0.45 m with
two targets, 0.46 m with three targets, and 0.55 m with four targets.


title:
Energy-Efficient Resource Allocation in OFDMA Systems with Hybrid Energy
  Harvesting Base Station

abstract:
  We study resource allocation algorithm design for energy-efficient
communication in an OFDMA downlink network with hybrid energy harvesting base
station. Specifically, an energy harvester and a constant energy source driven
by a non-renewable resource are used for supplying the energy required for
system operation. We first consider a deterministic offline system setting. In
particular, assuming availability of non-causal knowledge about energy arrivals
and channel gains, an offline resource allocation problem is formulated as a
non-convex optimization problem taking into account the circuit energy
consumption, a finite energy storage capacity, and a minimum required data
rate. We transform this non-convex optimization problem into a convex
optimization problem by applying time-sharing and fractional programming which
results in an efficient asymptotically optimal offline iterative resource
allocation algorithm. In each iteration, the transformed problem is solved by
using Lagrange dual decomposition. The obtained resource allocation policy
maximizes the weighted energy efficiency of data transmission. Subsequently, we
focus on online algorithm design. A stochastic dynamic programming approach is
employed to obtain the optimal online resource allocation algorithm which
requires a prohibitively high complexity. To strike a balance between system
performance and computational complexity, we propose a low complexity
suboptimal online iterative algorithm which is motivated by the offline
optimization.


title: Real Nullstellensatze and *-ideals in *-algebras

abstract:
  Let F denote either the real or complex field. An ideal I in the free
*-algebra F<x,x*> in g freely noncommuting variables and their formal adjoints
is a *-ideal if I = I*. When a real *-ideal has finite codimension, it
satisfies a strong Nullstellensatz. Without the finite codimension assumption,
there are examples of such ideals which do not satisfy, very liberally
interpreted, any Nullstellensatz. A polynomial p in F<x,x*> is analytic if it
is a polynomial in the variables {x} only; that is if p in F<x>. As shown in
this article, *-ideals generated by analytic polynomials do satisfy a natural
Nullstellensatz and those generated by homogeneous analytic polynomials have a
particularly simple description. The article also connects the results here for
*-ideals to the literature on Nullstellensatz for left ideals in *-algebras
generally and in F<x,x*> in particular. It also develops the concomitant
general theory of *-ideals in general *-algebras.


title: Hyperbolicity, automorphic forms and Siegel modular varieties

abstract:
  We study the hyperbolicity of compactifications of quotients of bounded
symmetric domains by arithmetic groups. We prove that, up to an \'etale cover,
they are Kobayashi hyperbolic modulo the boundary. Applying our techniques to
Siegel modular varieties, we improve some former results of Nadel on the
non-existence of certain level structures on abelian varieties over complex
function fields.


title: Entropic control of particle sizes during viral self-assembly

abstract:
  Morphologic diversity is observed across all families of viruses. Yet these
supra-molecular assemblies are produced most of the time in a spontaneous way
through complex molecular self-assembly scenarios. The modeling of these
phenomena remains a challenging problem within the emerging field of Physical
Virology. We present in this work a theoretical analysis aiming at highlighting
the particular role of configuration entropy in the control of viral particle
size distribution. Specializing this model to retroviruses like HIV-1, we
predict a new mechanism of entropic control of both RNA uptake into the viral
particle, and of the particle's size distribution. Evidence of this peculiar
behavior has been recently reported experimentally.


title:
A Search for Rapidly Spinning Pulsars and Fast Transients in
  Unidentified Radio Sources with the NRAO 43-Meter Telescope

abstract:
  We have searched 75 unidentified radio sources selected from the NRAO VLA Sky
Survey (NVSS) catalog for the presence of rapidly spinning pulsars and short,
dispersed radio bursts. The sources are radio bright, have no identifications
or optical source coincidences, are more than 5% linearly polarized, and are
spatially unresolved in the catalog. If these sources are fast-spinning pulsars
(e.g. sub-millisecond pulsars), previous large-scale pulsar surveys may have
missed detection due to instrumental and computational limitations, eclipsing
effects, or diffractive scintillation. The discovery of a sub-millisecond
pulsar would significantly constrain the neutron star equation of state and
would have implications for models predicting a rapid slowdown of highly
recycled X-ray pulsars to millisecond periods from, e.g., accretion disk
decoupling. These same sources were previously searched unsuccessfully for
pulsations at 610 MHz with the Lovell Telescope at Jodrell Bank. This new
search was conducted at a different epoch with a new 800 MHz backend on the
NRAO 43-meter Telescope at a center frequency of 1200 MHz. Our search was
sensitive to sub-millisecond pulsars in highly accelerated binary systems and
to short transient pulses. No periodic or transient signals were detected from
any of the target sources. We conclude that diffractive scintillation,
dispersive smearing, and binary acceleration are unlikely to have prevented
detection of the large majority of the sources if they are pulsars, though we
cannot rule out eclipsing, nulling or intermittent emission, or radio
interference as possible factors for some non-detections. Other (speculative)
possibilities for what these sources might be include radio-emitting magnetic
cataclysmic variables or older pulsars with aligned magnetic and spin axes.


title:
An Ontology for Modelling and Supporting the Process of Authoring
  Technical Assessments

abstract:
  In this paper, we present a semantic web approach for modelling the process
of creating new technical and regulatory documents related to the Building
sector. This industry, among other industries, is currently experiencing a
phenomenal growth in its technical and regulatory texts. Therefore, it is
urgent and crucial to improve the process of creating regulations by automating
it as much as possible. We focus on the creation of particular technical
documents issued by the French Scientific and Technical Centre for Building
(CSTB), called Technical Assessments, and we propose services based on Semantic
Web models and techniques for modelling the process of their creation.


title:
RX J0513.1+0851 AND RX J0539.9+0956: Two Young, Rapidly Rotating,
  Spectroscopic Binary Stars

abstract:
  RX J0513.1+0851 and RX J0539.9+0956 were previously identified as young,
low-mass, single-lined spectroscopic binary systems and classified as
weak-lined T Tauri stars at visible wavelengths. Here we present radial
velocities, spectral types, vsini values, and flux ratios for the components in
these systems resulting from two-dimensional cross-correlation analysis. These
results are based on high-resolution, near-infrared spectroscopy taken with the
Keck II telescope to provide a first characterization of these systems as
double-lined rather than single-lined. It applies the power of infrared
spectroscopy to the detection of cool secondaries; the flux scales as a less
steep function of mass in the infrared than in the visible, thus enabling an
identification of low-mass secondaries. We found that the RX J0513.1+0851 and
RX J0539.9+0956 primary stars are fast rotators, 60 km/s and 80 km/s
respectively; this introduces extra difficulty in the detection of the
secondary component as a result of the quite broad absorption lines. To date,
these are the highest rotational velocities measured for a pre-main sequence
spectroscopic binary. The orbital parameters and mass ratios were determined by
combining new visible light spectroscopy with our infrared data for both
systems. For RX J0513.1+0851, we derived a period of ~4 days and a mass ratio
of q = 0.46 +/- 0.01 and for RX J0539.9+0956, a period of ~1117 days and a mass
ratio of q = 0.66 +/- 0.01. Based on our derived properties for the stellar
components, we estimate the luminosities and hence distances to these binaries
at 220 pc and 90 pc. They appear to be significantly closer than previously
estimated.


title: Short wavelength magnetic buoyancy instability

abstract:
  Magnetic buoyancy instability plays an important role in the evolution of
astrophysical magnetic fields. Here we revisit the problem introduced by
\citet{Gilman_1970} of the short wavelength linear stability of a plane layer
of compressible isothermal fluid permeated by a horizontal magnetic field of
strength decreasing with height. Dissipation of momentum and magnetic field is
neglected. By the use of a Rayleigh-Schr\"odinger perturbation analysis, we
explain in detail the limit in which the transverse horizontal wavenumber of
the perturbation, denoted by $k$, is large (i.e.\ short horizontal wavelength)
and show that the fastest growing perturbations become localized in the
vertical direction as $k$ is increased. The growth rates are determined by a
function of the vertical coordinate $z$ since, in the large $k$ limit, the
eigenmodes are strongly localized in the vertical direction. We consider in
detail the case of two-dimensional perturbations varying in the directions
perpendicular to the magnetic field, which, for sufficiently strong field
gradients, are the most unstable. The results of our analysis are backed up by
comparison with a series of initial value problems. Finally we extend the
analysis to three-dimensional perturbations.


title:
Local breakdown of the quantum Hall effect in narrow single layer
  graphene Hall devices

abstract:
  We have analyzed the breakdown of the quantum Hall effect in 1 micrometer
wide Hall devices fabricated from an exfoliated monolayer graphene transferred
on SiOx. We have observed that the deviation of the Hall resistance from its
quantized value is weakly dependent on the longitudinal resistivity up to
current density of 5 A/m, where the Hall resistance remains quantized even when
the longitudinal resistance increases monotonously with the current. Then a
collapse in the quantized resistance occurs while longitudinal resistance keeps
its gradual increase. The exponential increase of the conductivity with respect
to the current suggests impurity mediated inter-Landau level scattering as the
mechanism of the breakdown. The results are interpreted as the strong variation
of the breakdown behavior throughout the sample due to the randomly distributed
scattering centers that mediates the breakdown.


title:
Spatially Addressable Readout and Erasure of an Image in a Gradient Echo
  Memory

abstract:
  We show that portions of an image written into a gradient echo memory can be
individually retrieved or erased on demand, an important step towards
processing a spatially multiplexed quantum signal. Targeted retrieval is
achieved by locally addressing the transverse plane of the storage medium, a
warm 85Rb vapor, with a far-detuned control beam. Spatially addressable erasure
is similarly implemented by imaging a bright beam tuned near the 85Rb D1 line
in order to scatter photons and induce decoherence. Under our experimental
conditions atomic diffusion is shown to impose an upper bound on the effective
spatial capacity of the memory. The decoherence induced by the optical eraser
is characterized and modeled as the response of a two level atom in the
presence of a strong driving field.


title: Voevodsky's Univalence Axiom in homotopy type theory

abstract:
  In this short note we give a glimpse of homotopy type theory, a new field of
mathematics at the intersection of algebraic topology and mathematical logic,
and we explain Vladimir Voevodsky's univalent interpretation of it. This
interpretation has given rise to the univalent foundations program, which is
the topic of the current special year at the Institute for Advanced Study.


title: Generic conditions for stable hybrid stars

abstract:
  We study the mass-radius curve of hybrid stars, assuming a single first-order
phase transition between nuclear and quark matter, with a sharp interface
between the quark matter core and nuclear matter mantle. We use a generic
parameterization of the quark matter equation of state, which has a constant,
i.e. density-independent, speed of sound ("CSS"). We argue that this
parameterization provides a framework for comparison and empirical testing of
models of quark matter. We obtain the phase diagram of possible forms of the
hybrid star mass-radius relation, where the control parameters are the
transition pressure, energy density discontinuity, and the quark matter speed
of sound. We find that this diagram is sensitive to the quark matter parameters
but fairly insensitive to details of the nuclear matter equation of state.
  We calculate the maximum hybrid star mass as a function of the parameters of
the quark matter EoS, and find that there are reasonable values of those
parameters that give rise to hybrid stars with mass above $2\,M_\odot$.


title: A Self-consistent Model of the Black Hole Evaporation

abstract:
  We construct a self-consistent model which describes a black hole from
formation to evaporation including the back reaction from the Hawking
radiation. In the case where a null shell collapses, at the beginning the
evaporation occurs, but it stops eventually, and a horizon and singularity
appear. On the other hand, in the generic collapse process of a continuously
distributed null matter, the black hole evaporates completely without forming a
macroscopically large horizon nor singularity. We also find a stationary
solution in the heat bath, which can be regarded as a normal thermodynamic
object.


title:
The role of the scalar curvature in some singularly perturbed coupled
  elliptic systems on Riemannian manifolds

abstract:
  Given a 3-dimensional Riemannian manifold (M,g), we investigate the existence
of positive solutions of singularly perturbed Klein-Gordon-Maxwell systems and
Schroedinger-Maxwell systems on M, with a subcritical nonlinearity. We prove
that when the perturbation parameter epsilon is small enough, any stable
critical point x_0 of the scalar curvature of the manifold (M,g) generates a
positive solution (u_eps,v_eps) to both the systems such that u_eps
concentrates at xi_0 as epsilon goes to zero.