title:
Differential Geometry Perspective of Shape Coherence and Curvature
  Evolution by Finite-Time Non-hyperbolic Splitting

abstract:
  Mixing, and coherence are fundamental issues at the heart of understanding
transport in fluid dynamics and other non-autonomous dynamical systems.
Recently, the notion of coherence has come to a more rigorous footing, and
particularly within the recent advances of finite-time studies of
non-autonomous dynamical systems. Here we define shape coherent sets as a means
to emphasize the intuitive notion of ensembles which "hold together" for some
period of time, and we contrast this notion to other recent perspectives of
coherence, notably "coherent pairs", and likewise also to the geodesic theory
of material lines. We will relate shape coherence to the differential geometry
concept of curve congruence through matching curvatures. We show that points in
phase space where there is a zero-splitting between stable and unstable
manifolds locally correspond to points where curvature will evolve only slowly
in time. Then we develop curves of points with zero-angle, meaning
non-hyperbolic splitting, by continuation methods in terms of the implicit
function theorem. From this follows a simple ODE description of the boundaries
of shape coherent sets. We will illustrate our methods with popular benchmark
examples, and further investigate the intricate structure of foliations
geometry.


title: Multifractals, Mumford curves, and Eternal Inflation

abstract:
  We relate the Eternal Symmetree model of Harlow, Shenker, Stanford, and
Susskind to constructions of stochastic processes arising from quantum
statistical mechanical systems on Cuntz--Krieger algebras. We extend the
eternal inflation model from the Bruhat--Tits tree to quotients by p-adic
Schottky groups, again using quantum statistical mechanics on graph algebras.


title: From Brans-Dicke gravity to a geometrical scalar-tensor theory

abstract:
  We consider an approach to Brans-Dicke theory of gravity in which the scalar
field has a geometrical nature. By postulating the Palatini variation, we find
out that the role played by the scalar field consists in turning the space-time
geometry into a Weyl integrable manifold. This procedure leads to a
scalar-tensor theory that differs from the original Brans-Dicke theory in many
aspects and presents some new features.


title:
Ce3+:CaSc2O4 Crystal Fibers for Green Light Emission: Growth Issues and
  Characterization

abstract:
  Ce3+ is known to show broad optical emission peaking in the green spectral
range. For the stabilization of 3-valent cerium in ceramic phosphors such as
calcium scandate CaSc2O4, often co-doping with sodium for charge compensation
is performed (Na+, Ce3+ = 2 Ca2+). At the melting point of CaSc2O4 (ca. 2110
deg C), however, alkaline oxides evaporate completely and co-doping is thus no
option for crystal growth from the melt. It is shown that even without
co-doping Ce3+:CaSc2O4 crystal fibers can be grown from the melt by
laser-heated pedestal growth (LHPG) in a suitable reactive atmosphere. Reactive
means here that the oxygen partial pressure is a function of temperature and
pO2(T) rises for this atmosphere in such a way that Ce3+ is kept stable for all
T. Crystal fibers with ca. 1 mm diameter and up to 50 mm length were grown and
characterized. Differential thermal analysis (DTA) was performed in the
pseudo-binary system CaO-Sc2O3, and the specific heat capacity cp(T) of CaSc2O4
was measured up to 1240 K by differential scanning calorimetry (DSC). Near and
beyond the melting point of calcium scandate significant evaporation of calcium
tends to shift the melt composition towards the Sc2O3 side. Measurements and
thermodynamic calculations reveal quantitative data on the fugacities of
evaporating species.


title:
Population genetic consequences of the Allee effect and the role of
  offspring-number variation

abstract:
  A strong demographic Allee effect in which the expected population growth
rate is negative below a certain critical population size can cause high
extinction probabilities in small introduced populations. However, many species
are repeatedly introduced to the same location and eventually one population
may overcome the Allee effect by chance. With the help of stochastic models, we
investigate how much genetic diversity such successful populations harbour on
average and how this depends on offspring-number variation, an important source
of stochastic variability in population size. We find that with increasing
variability, the Allee effect increasingly promotes genetic diversity in
successful populations. Successful Allee-effect populations with highly
variable population dynamics escape rapidly from the region of small population
sizes and do not linger around the critical population size. Therefore, they
are exposed to relatively little genetic drift. We show that here---unlike in
classical population genetics models---the role of offspring-number variation
cannot be accounted for by an effective-population-size correction. Thus, our
results highlight the importance of detailed biological knowledge, in this case
on the probability distribution of family sizes, when predicting the
evolutionary potential of newly founded populations or when using genetic data
to reconstruct their demographic history.


title: Hydrodynamical simulations of a compact source scenario for G2

abstract:
  The origin of the dense gas cloud G2 discovered in the Galactic Center
(Gillessen et al. 2012) is still a debated puzzle. G2 might be a diffuse cloud
or the result of an outflow from an invisible star embedded in it. We present
here detailed simulations of the evolution of winds on G2's orbit. We find that
the hydrodynamic interaction with the hot atmosphere present in the Galactic
Center and the extreme gravitational field of the supermassive black hole must
be taken in account when modeling such a source scenario. We find that the
hydrodynamic interaction with the hot atmosphere present in the Galactic Center
and the extreme gravitational field of the supermassive black hole must be
taken in account when modeling such a source scenario. We also find that in
this scenario most of the Br\gamma\ luminosity is expected to come from the
highly filamentary densest shocked wind material. G2's observational properties
can be used to constrain the properties of the outflow and our best model has a
mass outflow rate of Mdot,w=8.8 x 10^{-8} Msun/yr and a wind velocity of vw =
50 km/s. These values are compatible with those of a young TTauri star wind, as
already suggested by Scoville & Burkert (2013).


title:
Jet Quenching and Its Azimuthal Anisotropy in AA and possibly High
  Multiplicity pA and dA Collisions

abstract:
  We report our calculation of jet quenching and its azimuthal anisotropy in
the high energy AA and high multiplicity pA and dA collisions. The purpose of
this study is twofold. First, we improve our previous event-by-event studies,
by properly implementing $p_t$ dependence in the modeling. We show that, within
the jet "monography" scenario featuring a strong near-Tc-enhancement of jet
energy loss, the computed high-$p_t$ nuclear modification factor $R_{AA}$ and
the harmonic coefficients in its azimuthal anisotropy $v_{2,\,3,\,4}$, agree
well with the available data from both Relativistic Heavy Ion Collider (RHIC)
and Large Hadron Collider (LHC). Second, in light of current discussions on
possible final state collective behavior in the high-multiplicity pPb and dAu
collisions, we examine the implication of final state jet attenuation in such
collisions, by applying the same model used in AA collisions and quantifying
the corresponding $R_{pA}$ and $R_{dA}$ and their azimuthal anisotropy. The
high-$p_t$ $V_n$ provide a set of clean indicators of final state energy loss.
In particular we find in the most central pPb (5.02 TeV) and dAu (200 GeV)
collisions, $V_2$ is on the order of $0.01$ and $0.1$ respectively, measurable
with current experimental accuracy. In addition, our high-$p_t$ $R_{dA}$ is
around $0.6$ which is compatible with preliminary dAu results from RHIC.


title: Telegraph Processes with Random Jumps and Complete Market Models

abstract:
  We propose a new generalisation of jump-telegraph process with variable
velocities and jumps. Amplitude of the jumps and velocity values are random,
and they depend on the time spent by the process in the previous state of the
underlying Markov process.
  This construction is applied to markets modelling. The distribution densities
and the moments satisfy some integral equations of the Volterra type. We use
them for characterisation of the equivalent risk-neutral measure and for the
expression of historical volatility in various settings. The fundamental
equation is derived by similar arguments.
  Historical volatilities are computed numerically.


title: Notes on $\log(\zeta(s))^{\prime\prime}$

abstract:
  Motivated by the connection to the pair correlation of the Riemann zeros, we
investigate the second derivative of the logarithm of the Riemann zeta
function, in particular the zeros of this function. Theorem 1 gives a zero-free
region. Theorem 2 gives an asymptotic estimate for the number of nontrivial
zeros to height T. Theorem 3 is a zero density estimate.


title: G-Convergence, Dirichlet to Neumann maps and invisibility

abstract:
  We establish optimal conditions under which the G-convergence of linear
elliptic operators implies the convergence of the corresponding Dirichlet to
Neumann maps. As an application we show that the approximate cloaking isotropic
materials from [ Greenleaf, A.; Kurylev, Y.; Lassas, M.; Uhlmann, G.
Approximate quantum and acoustic cloaking. J. Spectr. Theory (2011), no. 1,
27--80.] are independent of the source.


title: Challenges in computational lower bounds

abstract:
  We draw two incomplete, biased maps of challenges in computational complexity
lower bounds.


title:
Existence of Anisotropic Spin Fluctuations at Low Temperature in the
  Normal Phase of the Superconducting Ferromagnet UCoGe

abstract:
  Thermal conductivity measurements have been performed on the superconducting
ferromagnet UCoGe down to very low temperature and under magnetic field. In
addition to the electronic quasiparticle thermal conductivity, additional
contributions to the thermal transport are detected: they are sensitive to the
amplitude and direction of the magnetic field, and at low temperature, they
display a strong anisotropy with the heat current direction. We identify these
contributions as arising from magnetic fluctuations. Detection of such
fluctuations on the thermal transport in 3D weak ferromagnets is very rare if
not unique, and pledges for a strongly itinerant character of the magnetism of
UCoGe.


title: Testing the stochastic LapH method in the twisted mass formulation

abstract:
  We present first results using the stochastic Laplace-Heaviside (sLapH)
method in the twisted mass formulation. The calculations are performed on gauge
configurations provided by the European Twisted Mass (ETM) collaboration with
2+1+1 dynamical quark flavours at a single value of the lattice spacing. In
particular, we compute disconnected contributions to flavour singlet
pseudo-scalar mesons and compare sLapH to standard volume noise methods.


title: Elements of Physics for the 21st century

abstract:
  Given the experimental precision in condensed matter physics -- positions are
measured with errors of less than 0.1pm, energies with about 0.1meV, and
temperature levels are below 20mK -- it can be inferred that standard quantum
mechanics, with its inherent uncertainties, is a model at the end of its
natural lifetime. In this presentation I explore the elements of a future
deterministic framework based on the synthesis of wave mechanics and density
functional theory at the single-electron level.


title: On the multicolor Ramsey number of a graph with m edges

abstract:
  The multicolor Ramsey number $r_k(F)$ of a graph $F$ is the least integer $n$
such that in every coloring of the edges of $K_n$ by $k$ colors there is a
monochromatic copy of $F$. In this short note we prove an upper bound on
$r_k(F)$ for a graph $F$ with $m$ edges and no isolated vertices of the form
$k^{6km^{2/3}}$ addressing a question of Sudakov [ Adv. Math. 227 (2011), no.
1, 601--609]. Furthermore, the constant in the exponent in the case of
bipartite $F$ and two colors is lowered so that $r_2(F)\le
2^{(1+o(1))2\sqrt{2m}}$ improving the result of Alon, Krivelevich and Sudakov
[Combin. Probab. Comput. 12 (2003), no. 5--6, 477--494].


title: Reversing quantum trajectories with analog feedback

abstract:
  We demonstrate the active suppression of transmon qubit dephasing induced by
dispersive measurement, using parametric amplification and analog feedback. By
real-time processing of the homodyne record, the feedback controller reverts
the stochastic quantum phase kick imparted by the measurement on the qubit. The
feedback operation matches a model of quantum trajectories with measurement
efficiency $\tilde{\eta} \approx 0.5$, consistent with the result obtained by
postselection. We overcome the bandwidth limitations of the amplification chain
by numerically optimizing the signal processing in the feedback loop and
provide a theoretical model explaining the optimization result.


title: Collisional Thermalization of Hydrogen and Helium in Solar Wind Plasma

abstract:
  In situ observations of the solar wind frequently show the temperature of
$\alpha$-particles (fully ionized helium), $T_\alpha$, to significantly differ
from that of protons (ionized hydrogen), $T_p$. Many heating processes in the
plasma act preferentially on $\alpha$-particles, even as collisions among ions
act to gradually establish thermal equilibrium. Measurements from the
$\textit{Wind}$ spacecraft's Faraday cups reveal that, at $r=1.0\ \textrm{AU}$
from the Sun, the observed values of the $\alpha$-proton temperature ratio,
$\theta_{\alpha p} \equiv T_\alpha\,/\,T_p$ has a complex, bimodal
distribution. This study applied a simple model for the radial evolution of
$\theta_{\alpha p}$ to these data to compute expected values of $\theta_{\alpha
p}$ at $r=0.1\ \textrm{AU}$. These inferred $\theta_{\alpha p}$-values have no
trace of the bimodality seen in the $\theta_{\alpha p}$-values measured at
$r=1.0\ \textrm{AU}$ but are instead consistent with the actions of the known
mechanisms for $\alpha$-particle preferential heating. This result underscores
the importance of collisional processes in the dynamics of the solar wind and
suggests that similar mechanisms may lead to preferential $\alpha$-particle
heating in both slow and fast wind.


title:
Dimension estimates for sets of uniformly badly approximable systems of
  linear forms

abstract:
  The set of badly approximable $m \times n $ matrices is known to have
Hausdorff dimension $mn $. Each such matrix comes with its own approximation
constant $c$, and one can ask for the dimension of the set of badly
approximable matrices with approximation constant greater than or equal to some
fixed $c$. In the one-dimensional case, a very precise answer to this question
is known. In this note, we obtain upper and lower bounds in higher dimensions.


title: p-filiform Leibniz algebras of maximum length

abstract:
  The descriptions (up to isomorphism) of naturally graded $p$-filiform Leibniz
algebras and $p$-filiform ($p\leq 3$) Leibniz algebras of maximum length are
known. In this paper we study the gradation of maximum length for $p$-filiform
Leibniz algebras. The present work aims at the classification of complex
$p$-filiform ($p \geq 4$) Leibniz algebras of maximum length.


title:
Relaxation of a Quantum Emitter Resonantly Coupled to a Metal
  Nanoparticle

abstract:
  Presence of a metal nanoparticle near a quantum dipole emitter, when a
localized surface plasmon mode is excited via the resonant coupling with an
excited quantum dipole, changes dramatically the relaxation dynamics: it is no
longer described by an exponential decay but exhibits step-like behavior. The
main physical consequence of this relaxation process is that the emission,
being largely determined by the metal nanoparticle, comes out with a
substantial delay. A large number of system parameters in our analytical
description opens new possibilities for controlling quantum emitter dynamics.


title:
A self-consistent phase-space distribution function for the anisotropic
  Dark Matter halo of the Milky Way

abstract:
  Dark Matter (DM) direct detection experiments usually assume the simplest
possible 'Standard Halo Model' for the Milky Way (MW) halo in which the
velocity distribution is Maxwellian. This model assumes that the MW halo is an
isotropic, isothermal sphere, hypotheses that are unlikely to be valid in
reality. An alternative approach is to derive a self-consistent solution for a
particular mass model of the MW (i.e. obtained from its gravitational
potential) using the Eddington formalism, which assumes isotropy. In this paper
we extend this approach to incorporate an anisotropic phase-space distribution
function. We perform Bayesian scans over the parameters defining the mass model
of the MW and parameterising the phase-space density, implementing constraints
from a wide range of astronomical observations. The scans allow us to estimate
the precision reached in the reconstruction of the velocity distribution (for
different DM halo profiles). As expected, allowing for an anisotropic velocity
tensor increases the uncertainty in the reconstruction of f(v) but the
distribution can still be determined with a precision of a factor of 4-5. The
mean velocity distribution resembles the isotropic case, however the amplitude
of the high-velocity tail is up to a factor of 2 larger. Our results agree with
the phenomenological parametrization proposed in Mao et al. (2013) as a good
fit to N-body simulations (with or without baryons), since their velocity
distribution is contained in our 68% credible interval.


title:
3D Prominence-hosting Magnetic Configurations: Creating a Helical
  Magnetic Flux Rope

abstract:
  The magnetic configuration hosting prominences and their surrounding coro-
nal structure is a key research topic in solar physics. Recent theoretical and
observational studies strongly suggest that a helical magnetic flux rope is an
es- sential ingredient to fulfill most of the theoretical and observational
requirements for hosting prominences. To understand flux rope formation details
and obtain magnetic configurations suitable for future prominence formation
studies, we here report on three-dimensional isothermal magnetohydrodynamic
simulations including finite gas pressure and gravity. Starting from a
magnetohydrostatic corona with a linear force-free bipolar magnetic field, we
follow its evolution when introducing vortex flows around the main polarities
and converging flows towards the polarity inversion line near the bottom of the
corona. The con- verging flows bring feet of different loops together at the
polarity inversion line and magnetic reconnection and flux cancellation
happens. Inflow and outflow signatures of the magnetic reconnection process are
identified, and the thereby newly formed helical loops wind around pre-existing
ones so that a complete flux rope grows and ascends. When a macroscopic flux
rope is formed, we switch off the driving flows and find that the system
relaxes to a stable state containing a helical magnetic flux rope embedded in
an overlying arcade structure. A major part of the formed flux rope is threaded
by dipped field lines which can stably support prominence matter, while the
total mass of the flux rope is in the order of 4-5.e14 g.


title: Learning Pairwise Graphical Models with Nonlinear Sufficient Statistics

abstract:
  We investigate a generic problem of learning pairwise exponential family
graphical models with pairwise sufficient statistics defined by a global
mapping function, e.g., Mercer kernels. This subclass of pairwise graphical
models allow us to flexibly capture complex interactions among variables beyond
pairwise product. We propose two $\ell_1$-norm penalized maximum likelihood
estimators to learn the model parameters from i.i.d. samples. The first one is
a joint estimator which estimates all the parameters simultaneously. The second
one is a node-wise conditional estimator which estimates the parameters
individually for each node. For both estimators, we show that under proper
conditions the extra flexibility gained in our model comes at almost no cost of
statistical and computational efficiency. We demonstrate the advantages of our
model over state-of-the-art methods on synthetic and real datasets.


title:
What season suits you best? Seasonal light changes and cyanobacterial
  competition

abstract:
  Nearly all living organisms, including some bacterial species, exhibit
biological processes with a period of about 24 h called circadian (from the
Latin circa, about, dies, day) rhythms. These rhythms allow living organisms to
anticipate the daily alternation of light and darkness. Experiments carried out
in cyanobacteria have shown the adaptive value of circadian clocks. In these
experiments a wild type cyanobacterial strain (with a 24 h circadian rhythm)
and a mutant strain (with a longer or shorter period) grow in competition. In
different experiments the external light dark cycle was changed in order to
match the circadian period of the different strains, revealing that the strain
whose circadian period matches the light-dark has a larger fitness. As a
consequence the initial population of one strain grows while the other decays.
  These experiments were made under fixed light and dark intervals. However, in
Nature this relationship changes according to the season. Therefore, seasonal
changes in light could affect the results of the competition. Using a
theoretical model we analyze how modulation of light can change the survival of
the different cyanobacterial strains. Our results show that there is a clear
shift in the competition due to the modulation of light, which could be
verified experimentally.


title: Bi-Criteria and Approximation Algorithms for Restricted Matchings

abstract:
  In this work we study approximation algorithms for the \textit{Bounded Color
Matching} problem (a.k.a. Restricted Matching problem) which is defined as
follows: given a graph in which each edge $e$ has a color $c_e$ and a profit
$p_e \in \mathbb{Q}^+$, we want to compute a maximum (cardinality or profit)
matching in which no more than $w_j \in \mathbb{Z}^+$ edges of color $c_j$ are
present. This kind of problems, beside the theoretical interest on its own
right, emerges in multi-fiber optical networking systems, where we interpret
each unique wavelength that can travel through the fiber as a color class and
we would like to establish communication between pairs of systems. We study
approximation and bi-criteria algorithms for this problem which are based on
linear programming techniques and, in particular, on polyhedral
characterizations of the natural linear formulation of the problem. In our
setting, we allow violations of the bounds $w_j$ and we model our problem as a
bi-criteria problem: we have two objectives to optimize namely (a) to maximize
the profit (maximum matching) while (b) minimizing the violation of the color
bounds. We prove how we can "beat" the integrality gap of the natural linear
programming formulation of the problem by allowing only a slight violation of
the color bounds. In particular, our main result is \textit{constant}
approximation bounds for both criteria of the corresponding bi-criteria
optimization problem.


title: Construction of normal numbers via generalized prime power sequences

abstract:
  In the present paper the authors construct normal numbers in base $q$ by
concatenating $q$-adic expansions of prime powers $\lfloor\alpha
p^\theta\rfloor$ with $\alpha>0$ and $\theta>1$.


title: A partition identity and the universal mock theta function $g_2$

abstract:
  We prove analytic and combinatorial identities reminiscent of Schur's
classical partition theorem. Specifically, we show that certain families of
overpartitions whose parts satisfy gap conditions are equinumerous with
partitions whose parts satisfy congruence conditions. Furthermore, if small
parts are excluded, the resulting overpartitions are generated by the product
of a modular form and Gordon and McIntosh's universal mock theta function.
Finally, we give an interpretation for the universal mock theta function at
real arguments in terms of certain conditional probabilities.


title: Fermionic vacuum polarization in compactified cosmic string spacetime

abstract:
  We investigate the fermionic condensate (FC) and the vacuum expectation value
(VEV) of the energy-momentum tensor for a charged massive fermionic field in
the geometry of a cosmic string compactified along its axis. In addition, we
assume the presence of two types of magnetic fluxes: a flux running along the
cosmic string and another enclosed by the compact dimension. These fluxes give
rise to Aharanov-Bohm-like effects on the VEVs. The VEVs are decomposed into
two parts corresponding to the geometry of a straight cosmic string without
compactification plus a topological part induced by the compactification of the
string axis. Both contributions are even periodic functions of the magnetic
fluxes with period equal to the flux quantum. The vacuum energy density is
equal to the radial stress for the parts corresponding to the straight cosmic
string and the topological one. Moreover, the axial stress is equal to the
energy density for the parts corresponding to the straight cosmic string;
however, for massive fermionic field this does not occur for the topological
contributions. With respect to the dependence on the magnetic fluxes, both, the
fermionic condensate and the vacuum energy density, can be either positive or
negative. Moreover, for points near the string, the main contribution to the
VEVs comes from the straight cosmic string part, whereas at large distances the
topological ones dominate. In addition to the local characteristics of the
vacuum state, we also evaluate the part in the topological Casimir energy
induced by the string.


title: Zero modes of quantum graph Laplacians and an index theorem

abstract:
  We study zero modes of Laplacians on compact and non-compact metric graphs
with general self-adjoint vertex conditions. In the first part of the paper the
number of zero modes is expressed in terms of the trace of a unitary matrix
$\mathfrak{S}$ that encodes the vertex conditions imposed on functions in the
domain of the Laplacian. In the second part a Dirac operator is defined whose
square is related to the Laplacian. In order to accommodate Laplacians with
negative eigenvalues it is necessary to define the Dirac operator on a suitable
Kre\u{\i}n space. We demonstrate that an arbitrary, self-adjoint quantum graph
Laplacian admits a factorisation into momentum-like operators in a
Kre\u{\i}n-space setting. As a consequence, we establish an index theorem for
the associated Dirac operator and prove that the zero-mode contribution in the
trace formula for the Laplacian can be expressed in terms of the index of the
Dirac operator.


title: Evaluation of a College Freshman Diversity Research Program

abstract:
  Since 2005, the Pre-Major in Astronomy Program (Pre-MAP) at the University of
Washington (UW) Department of Astronomy has made a concentrated effort to
recruit and retain underrepresented undergraduates in science, technology,
engineering and mathematics (STEM). This paper evaluates Pre-MAP in the context
of the larger UW student population using data compiled by the University's
student database. We evaluate the Pre-MAP program in terms of our goals of
recruiting a more diverse population than the University and in terms of a
higher fraction of students successfully completing degrees. We find that
Pre-MAP serves a higher percentage of underrepresented minorities and equal
percentages of women compared to entering freshmen classes at UW. Additionally,
Pre-MAP has a higher percentage of degree completion with higher average GPA's
and similar time to completion when compared to UW as a whole and other STEM
majors, particularly with students that place into lower-level math courses
(such as basic algebra or pre-calculus).


title:
Describing massive neutrinos in cosmology as a collection of independent
  flows

abstract:
  A new analytical approach allowing to account for massive neutrinos in the
non-linear description of the growth of the large-scale structure of the
universe is proposed. Unlike the standard approach in which neutrinos are
described as a unique hot fluid, it is shown that the overall neutrino fluid
can be equivalently decomposed into a collection of independent flows. Starting
either from elementary conservation equations or from the evolution equation of
the phase-space distribution function, we derive the two non-linear motion
equations that each of these flows satisfies. Those fluid equations describe
the evolution of macroscopic fields. We explain in detail the connection
between the collection of flows we defined and the standard massive neutrino
fluid. Then, in the particular case of adiabatic initial conditions, we
explicitly check that, at linear order, the resolution of this new system of
equations reproduces the results obtained in the standard approach based on the
collisionless Boltzmann hierarchy. Besides, the approach advocated in this
paper allows to show how each neutrino flow settles into the cold dark matter
flow depending on initial velocities. It opens the way to a fully non-linear
treatment of the dynamical evolution of neutrinos in the framework of
large-scale structure growth.


title: The Rees Algebra of a monomial plane parametrization

abstract:
  We compute a minimal bigraded resolution of the Rees Algebra associated to a
proper rational parametrization of a monomial plane curve. We describe
explicitly both the bigraded Betti numbers and the maps of the resolution in
terms of a generalized version of the Euclidean Algorithm. We also explore the
relation between pencils of adjoints of the monomial plane curve and elements
in a suitable piece of the defining ideal of the Rees Algebra.


title:
The Bright Optical flash and Afterglow from the Gamma-Ray Burst GRB
  130427A

abstract:
  The optical light that is generated simultaneously with the x-rays and
gamma-rays during a gamma-ray burst (GRB) provides clues about the nature of
the explosions that occur as massive stars collapse to form black holes. We
report on the bright optical flash and fading afterglow from the powerful burst
GRB 130427A and present a comparison with the properties of the gamma-ray
emission that show correlation of the optical and >100 MeV photon flux light
curves during the first 7,000 seconds. We attribute this correlation to
co-generation in an external shock. The simultaneous, multi-color, optical
observations are best explained at early times by reverse shock emission
generated in the relativistic burst ejecta as it collides with surrounding
material and at late times by a forward shock traversing the circumburst
environment. The link between optical afterglow and >100 MeV emission suggests
that nearby early peaked afterglows will be the best candidates for studying
GRB emission at GeV/TeV energies.


title:
{\eta} and {\eta}' masses and decay constants from lattice QCD with
  2+1+1 quark flavours

abstract:
  We investigate the masses and decay constants of eta and eta' mesons using
the Wilson twisted mass formulation with N_f=2+1+1 dynamical quark flavours
based on gauge configurations of ETMC. We show how to efficiently subtract
excited state contributions to the relevant correlation functions and estimate
in particular the eta' mass with improved precision. After investigating the
strange quark mass dependence and the continuum and chiral extrapolations, we
present our results for masses and mixing angle(s) at the physical point. Using
chiral perturbation theory we also extract the decay constants f_l and f_s and
use them to estimate the decay widths of eta,\eta' to gamma gamma and the
transition form factor in the limit of large momentum transfer.


title:
Next-to-leading-order electroweak corrections to pp->WW->4 leptons in
  double-pole approximation at the LHC

abstract:
  We report on our calculation of next-to-leading-order electroweak corrections
to W-boson pair production at the LHC, taking into account off-shell effects
and spin correlations of the W bosons and their leptonic decays in the
framework of a double-pole approximation. We study the various contributions to
the electroweak corrections in detail and discuss their impact on selected
observables within a realistic event-selection setup.


title: The stellar-to-halo mass relation for Local Group galaxies

abstract:
  We contend that a single power law halo mass distribution is appropriate for
direct matching to the stellar masses of observed Local Group dwarf galaxies,
allowing the determination of the slope of the stellar mass-halo mass relation
for low mass galaxies. Errors in halo masses are well defined as the Poisson
noise of simulated local group realisations, which we determine using
constrained local universe simulations (CLUES). For the stellar mass range
10$^7$<M*<10$^8$M$_\odot$, for which we likely have a complete census of
observed galaxies, we find that the stellar mass-halo mass relation follows a
power law with slope of 3.1, significantly steeper than most values in the
literature. The steep relation between stellar and halo masses indicates that
Local Group dwarf galaxies are hosted by dark matter halos with a small range
of mass. Our methodology is robust down to the stellar mass to which the census
of observed Local Group galaxies is complete, but the significant uncertainty
in the currently measured slope of the stellar-to halo mass relation will
decrease dramatically if the Local Group completeness limit was
$10^{6.5}$M$\odot$ or below, highlighting the importance of pushing such limit
to lower masses and larger volumes.


title:
Sign conditions for injectivity of generalized polynomial maps with
  applications to chemical reaction networks and real algebraic geometry

abstract:
  We give necessary and sufficient conditions in terms of sign vectors for the
injectivity of families of polynomial maps with arbitrary real exponents
defined on the positive orthant. Our work relates and extends existing
injectivity conditions expressed in terms of Jacobian matrices and
determinants. In the context of chemical reaction networks with power-law
kinetics, our results can be used to preclude as well as to guarantee multiple
positive steady states. In the context of real algebraic geometry,our work
recognizes a prior result of Craciun, Garcia-Puente, and Sottile, together with
work of two of the authors, as the first partial multivariate generalization of
the classical Descartes' rule, which bounds the number of positive real roots
of a univariate real polynomial in terms of the number of sign variations of
its coefficients.


title: Characteristic subobjects in semi-abelian categories

abstract:
  We extend to semi-abelian categories the notion of characteristic subobject,
which is widely used in group theory and in the theory of Lie algebras.
Moreover, we show that many of the classical properties of characteristic
subgroups of a group hold in the general semi-abelian context, or in stronger
ones.


title: Recent developments in the tmLQCD software suite

abstract:
  We present an overview of recent developments in the tmLQCD software suite.
We summarise the features of the code, including actions and operators
implemented. In particular, we discuss the optimisation efforts for modern
architectures using the Blue Gene/Q system as an example.


title:
Metallic Conductance at the Interface of Tri-color Titanate
  Superlattices

abstract:
  Ultra-thin tri-color (tri-layer) titanate superlattices ([3u.c. LaTiO3/2u.c.
SrTiO3/3u.c. YTiO3], u.c. = unit cells) were grown in a layer-by-layer way on
single crystal TbScO3 (110) substrates by pulsed laser deposition. High sample
quality and electronic structure were characterized by the combination of
in-situ photoelectron and ex-situ structure and surface morphology probes.
Temperature-dependent sheet resistance indicates the presence of metallic
interfaces in both [3u.c. LaTiO3/2u.c. SrTiO3] bi-layers and all the tri-color
structures, whereas a [3u.c. YTiO3/2u.c. SrTiO3] bi-layer shows insulating
behavior. Considering that in the bulk YTiO3 is ferromagnetic below 30 K, the
tri-color titanate superlattices provide an opportunity to induce tunable spin-
polarization into the two-dimensional electron gas (2DEG) with Mott carriers.


title:
Rogue Waves In Nonlinear Schr\"odinger Models with Variable
  Coefficients: Application to Bose-Einstein Condensates

abstract:
  We explore the form of rogue wave solutions in a select set of case examples
of nonlinear Schr\"odinger equations with variable coefficients. We focus on
systems with constant dispersion, and present three different models that
describe atomic Bose-Einstein condensates in different experimentally relevant
settings. For these models, we identify exact rogue wave solutions. Our
analytical findings are corroborated by direct numerical integration of the
original equations, performed by two different schemes. Very good agreement
between numerical results and analytical predictions for the emergence of the
rogue waves is identified. Additionally, the nontrivial fate of small
numerically induced perturbations to the exact rogue wave solutions is also
discussed.


title:
The b-quark mass from non-perturbative $N_f=2$ Heavy Quark Effective
  Theory at $O(1/m_h)$

abstract:
  We report our final estimate of the b-quark mass from $N_f=2$ lattice QCD
simulations using Heavy Quark Effective Theory non-perturbatively matched to
QCD at $O(1/m_h)$. Treating systematic and statistical errors in a conservative
manner, we obtain $\overline{m}_{\rm b}^{\overline{\rm MS}}(2 {\rm
GeV})=4.88(15)$ GeV after an extrapolation to the physical point.


title: Tactical decompositions of designs over finite fields

abstract:
  An automorphism group of an incidence structure I induces a tactical
decomposition on I. It is well known that tactical decompositions of t-designs
satisfy certain necessary conditions which can be expressed as equations in
terms of the coefficients of tactical decomposition matrices. In this article
we present results obtained for tactical decompositions of q-analogs of
t-designs, more precisely, of 2-(v,k,lambda_2;q) designs. We show that
coefficients of tactical decomposition matrices of a design over finite field
satisfy an equation system analog to the one known for block designs.
Furthermore, taking into consideration specific properties of designs over the
binary field, we obtain an additional system of inequations for these
coefficients in that case.


title: A fresh look at (non)renormalizable QFTs

abstract:
  Abandoning dimensional regularization allows important simplifications in
loop calculations and gives a handle to interpret non-renormalizable Quantum
Field Theories. I review the current status of FDR, a fully four-dimensional
approach to the ultraviolet problem.


title:
Transformation of a Virgo Cluster Dwarf Irregular Galaxy by Ram Pressure
  Stripping: IC3418 and its Fireballs

abstract:
  We present optical imaging and spectroscopy and HI imaging of the Virgo
Cluster galaxy IC 3418, which is likely a "smoking gun" example of the
transformation of a dwarf irregular into a dwarf elliptical galaxy by ram
pressure stripping. IC 3418 has a spectacular 17 kpc length UV-bright tail
comprised of knots, head-tail, and linear stellar features. The only H-alpha
emission arises from a few HII regions in the tail, the brightest of which are
at the heads of head-tail UV sources whose tails point toward the galaxy
("fireballs"). Several of the elongated tail sources have H-alpha peaks
outwardly offset by 80-150 pc from the UV peaks, suggesting that gas clumps
continue to accelerate through ram pressure, leaving behind streams of newly
formed stars which have decoupled from the gas. Absorption line strengths,
measured from Keck DEIMOS spectra, together with UV colors, show star formation
stopped 300+/-100 Myr ago in the main body, and a strong starburst occurred
prior to quenching. While neither H-alpha nor HI emission are detected in the
main body of the galaxy, we have detected 4x10^7 M_sun of HI from the tail with
the VLA. The gas consumption timescale in the tail is relatively long, implying
that most of the stripped gas does not form stars but joins the ICM. The
velocities of tail HII regions, measured from Keck LRIS spectra, extend only a
small fraction of the way to the cluster velocity, suggesting that star
formation does not happen in more distant parts of the tail. Stars in the outer
tail have velocities exceeding the escape speed, but some in the inner tail
should fall back into the galaxy, forming halo streams. One likely fallback
stream is identified.


title: Evolution of Communities with Focus on Stability (extended abstract)

abstract:
  The detection of communities is an important tool used to analyze the social
graph of mobile phone users. Within each community, customers are susceptible
of attracting new ones, retaining old ones and/or accepting new products or
services through the leverage of mutual influences. The communities of users
are smaller units, easier to grasp, and allow for example the computation of
role analysis -- based on the centrality of an actor within his community.
  The problem of finding communities in static graphs has been widely studied.
However, from the point of view of a telecom analyst, to be really useful, the
detected communities must evolve as the social graph of communications changes
over time -- for example, in order to perform marketing actions on communities
and track the results of those actions over time. Additionally the behaviors of
communities of users over time can be used to predict future activity that
interests the telecom operators, such as subscriber churn or handset adoption.
Similary group evolution can provide insights for designing strategies, such as
the early warning of group churn.
  Stability is a crucial issue: the analysis performed on a given community
will be lost, if the analyst cannot keep track of this community in the
following time steps. This is the particular use case that we tackle in this
paper: tracking the evolution of communities in dynamic scenarios with focus on
stability.
  We propose two modifications to a widely used static community detection
algorithm. We then describe experiments to study the stability and quality of
the resulting partitions on real-world social networks, represented by monthly
call graphs for millions of subscribers.


title:
Magnetic field induced shell-to-core confinement transition in type-II
  semiconductor quantum wires

abstract:
  We investigate the excitonic properties of a core-multishell semiconductor
nanowire with type-II band mismatch, i.e. with spatially separated electrons
and holes, under an external magnetic field. Our results demonstrate that,
depending on the core wire radius, the carrier in the type-II band exhibits
either a quantum dot-like or a quantum ring-like energy spectrum, corresponding
to a carrier confinement in the core wire or in the outer shell, respectively.
In the latter, a shell-to-core confinement transition can be induced by
increasing the magnetic field intensity, which may lead to interesting
photocurrent properties of these confining structures, tunable by the external
field.


title: The muon anomalous magnetic moment, a view from the lattice

abstract:
  We review some of the issues that arise in attempts to compute the hadronic
corrections to the muon anomalous magnetic moment using Lattice QCD. We
concentrate on the dominant contribution, which requires an accurate evaluation
of the hadronic vacuum polarization.


title: N-expansive homeomorphisms on surfaces

abstract:
  We exploit the techniques developed in [Le] to study N-expansive
homeomorphisms on surfaces. We prove that when f is a 2-expansive homeomorphism
defined on a compact boundaryless surface M without wandering points then f is
expansive. This condition on the wandering set cannot be relaxed: we present an
example of a 2-expansive homeomorphisms on the bitorus with wandering points
that is not expansive.


title:
Operational constraints on state-dependent formulations of quantum
  error-disturbance trade-off relations

abstract:
  We argue for an operational requirement that all state-dependent measures of
disturbance should satisfy. Motivated by this natural criterion, we prove that
in any $d$-dimensional Hilbert space and for any pair of non-commuting
operators, $A$ and $B$, there exists a set of at least $2^{d-1}$ zero-noise,
zero-disturbance (ZNZD) states, for which the first observable can be measured
without noise and the second will not be disturbed. Moreover, we show that it
is possible to construct such ZNZD states for which the expectation value of
the commutator $[A,B]$ does not vanish. Therefore any state-dependent
error-disturbance relation, based on the expectation value of the commutator as
a lower bound, must violate the operational requirement. We also discuss
Ozawa's state-dependent error-disturbance relation in light of our results and
show that the disturbance measure used in this relation exhibits unphysical
properties. We conclude that the trade-off is inevitable only between
state-independent measures of error and disturbance.


title:
Distributions of the same type: non-equivalence of definitions in the
  discrete case

abstract:
  Distributions of the same type can be discussed in terms of distribution
functions as well as their integral transforms. For continuous distributions
they are equivalent. In this note it is shown that it is not so in the discrete
case.


title:
Effectively universal behavior of rotating neutron stars in general
  relativity makes them even simpler than their Newtonian counterparts

abstract:
  Recently it was shown that slowly rotating neutron stars exhibit an
interesting correlation between their moment of inertia $I$, their quadrupole
moment $Q$, and their tidal deformation Love number $\lambda$ (the I-Love-Q
relations), independently of the equation of state of the compact object. In
the present work a similar, more general, universality is shown to hold true
for all rotating neutron stars within General Relativity; the first four
multipole moments of the neutron star are related in a way independent of the
nuclear matter equation of state we assume. By exploiting this relation, we can
describe quite accurately the geometry around a neutron star with fewer
parameters, even if we don't know precisely the equation of state. Furthermore,
this universal behavior displayed by neutron stars, could promote them to a
more promising class of candidates (next to black holes) for testing theories
of gravity.


title: Dynamics of the entanglement spectrum in spin chains

abstract:
  We study the dynamics of the entanglement spectrum, that is the time
evolution of the eigenvalues of the reduced density matrices after a
bipartition of a one-dimensional spin chain. Starting from the ground state of
an initial Hamiltonian, the state of the system is evolved in time with a new
Hamiltonian. We consider both instantaneous and quasi adiabatic quenches of the
system Hamiltonian across a quantum phase transition. We analyse the Ising
model that can be exactly solved and the XXZ for which we employ the
time-dependent density matrix renormalisation group algorithm. Our results show
once more a connection between the Schmidt gap, i.e. the difference of the two
largest eigenvalues of the reduced density matrix and order parameters, in this
case the spontaneous magnetisation.


title: Heat kernel coefficients on Kahler manifolds

abstract:
  Polterovich proved a remarkable closed formula for heat kernel coefficients
of the Laplace operator on compact Riemannian manifolds involving powers of
Laplacians acting on the distance function. In the case of K\"ahler manifolds,
we prove a combinatorial formula for powers of the complex Laplacian and use it
to derive an explicit graph theoretic formula for the numerics in heat
coefficients as a linear combination of metric jets based on Polterovich's
formula.


title:
Unified Growth Theory: A puzzling collection of myths based on
  hyperbolic illusions

abstract:
  The Unified Growth Theory is a puzzling collection of myths based on
illusions created by hyperbolic distributions. Some of these myths are
discussed. The examination of data shows that the three stages of growth
(Malthusian Regime, Post-Malthusian Regime and Modern Growth Regime) did not
exist and that Industrial Revolution had no influence on the economic growth
and on the growth of human population. All elaborate explanations revolving
around phantom features created by hyperbolic illusions might be fascinating
but they are scientifically unacceptable and, consequently, they do not explain
the economic growth. The data clearly indicate that the economic growth was not
as complicated as described by the Unified Growth Theory but elegantly simple.


title:
A New Perspective on the Radio Active Zone at The Galactic Center -
  Feedback from Nuclear Activities

abstract:
  Based on our deep image of Sgr A using broadband data observed with the
Jansky VLA at 6 cm, we present a new perspective of the radio bright zone at
the Galactic center. We further show the radio detection of the X-ray
Cannonball, a candidate neutron star associated with the Galactic center SNR
Sgr A East. The radio image is compared with the Chandra X-ray image to show
the detailed structure of the radio counterparts of the bipolar X-ray lobes.
The bipolar lobes are likely produced by the winds from the activities within
Sgr A West, which could be collimated by the inertia of gas in the CND, or by
the momentum driving of Sgr A*; and the poloidal magnetic fields likely play an
important role in the collimation. The less-collimated SE lobe, in comparison
to the NW one, is perhaps due to the fact that the Sgr A East SN might have
locally reconfigured the magnetic field toward negative galactic latitudes. In
agreement with the X-ray observations, the time-scale of ~ $1\times10^4$ yr
estimated for the outermost radio ring appears to be comparable to the inferred
age of the Sgr A East SNR.


title: More on thermal probes of a strongly coupled anisotropic plasma

abstract:
  We extend the analysis of 1211.2199, where the photon production rate of an
anisotropic strongly coupled plasma with Nf<<Nc massless quarks was considered.
We allow here for non-vanishing quark masses and study how these affect the
spectral densities and conductivities. We also compute another important probe
of the plasma, the dilepton production rate. We consider generic angles between
the anisotropic direction and the photon and dilepton wave vectors, as well as
arbitrary quark masses and arbitrary values of the anisotropy parameter.
Generically, the anisotropy increases the production rate of both photons and
dileptons, compared with an isotropic plasma at the same temperature.


title:
NuSTAR discovery of a luminosity dependent cyclotron line energy in Vela
  X-1

abstract:
  We present NuSTAR observations of Vela X-1, a persistent, yet highly
variable, neutron star high-mass X-ray binary (HMXB). Two observations were
taken at similar orbital phases but separated by nearly a year. They show very
different 3-79 keV flux levels as well as strong variability during each
observation, covering almost one order of magnitude in flux. These observations
allow, for the first time ever, investigations on kilo-second time-scales of
how the centroid energies of cyclotron resonant scattering features (CRSFs)
depend on flux for a persistent HMXB. We find that the line energy of the
harmonic CRSF is correlated with flux, as expected in the sub-critical
accretion regime. We argue that Vela X-1 has a very narrow accretion column
with a radius of around 0.4 km that sustains a Coulomb interaction dominated
shock at the observed luminosities of Lx ~ 3x10^36 erg/s. Besides the prominent
harmonic line at 55 keV the fundamental line around 25 keV is clearly detected.
We find that the strengths of the two CRSFs are anti-correlated, which we
explain by photon spawning. This anti-correlation is a possible explanation for
the debate about the existence of the fundamental line. The ratio of the line
energies is variable with time and deviates significantly from 2.0, also a
possible consequence of photon spawning, which changes the shape of the line.
During the second observation, Vela X-1 showed a short off-state in which the
power-law softened and a cut-off was no longer measurable. It is likely that
the source switched to a different accretion regime at these low mass accretion
rates, explaining the drastic change in spectral shape.


title: The sign problem and Abelian lattice duality

abstract:
  For a large class of Abelian lattice models with sign problems, including the
case of non-zero chemical potential, duality maps models with complex actions
into dual models with real actions. For extended regions of parameter space,
calculable for each model, duality resolves the sign problem for both analytic
methods and computer simulations. Explicit duality relations are given for
models for spin and gauge models based on Z(N) and U(1) symmetry groups. The
dual forms are generalizations of the Z(N) chiral clock model and the lattice
Frenkel-Kontorova model, respectively. From these equivalences, rich sets of
spatially-modulated phases are found in the strong-coupling region of the
original models.


title:
Energy levels, radiative rates and electron impact excitation rates for
  transitions in Al X

abstract:
  Energy levels, radiative rates and lifetimes are calculated among the lowest
98 levels of the n <= 4 configurations of Be-like Al X. The GRASP
(General-purpose Relativistic Atomic Structure Package) is adopted and data are
provided for all E1, E2, M1 and M2 transitions. Similar data are also obtained
with the Flexible Atomic Code (FAC) to assess the accuracy of the calculations.
Based on comparisons between calculations with the two codes as well as with
available measurements, our listed energy levels are assessed to be accurate to
better than 0.3%. However, the accuracy for radiative rates and lifetimes is
estimated to be about 20%. Collision strengths are also calculated for which
the Dirac Atomic R-matrix Code (DARC) is used. A wide energy range (up to 380
Ryd) is considered and resonances resolved in a fine energy mesh in the
thresholds region. The collision strengths are subsequently averaged over a
Maxwellian velocity distribution to determine effective collision strengths up
to a temperature of 1.6x10$^7$ K. Our results are compared with the previous
(limited) atomic data and significant differences (up to a factor of 4) are
noted for several transitions, particularly those which are not allowed in jj
coupling.


title: Statistical Detection of Potentially Fabricated Data

abstract:
  Scientific fraud is an increasingly vexing problem. Many current programs for
fraud detection focus on image manipulation, while techniques for detection
based on anomalous patterns that may be discoverable in the underlying
numerical data get much less attention, even though these techniques are often
easy to apply. We employed three such techniques in a case study in which we
considered data sets from several hundred experiments. We compared patterns in
the data sets from one research teaching specialist (RTS), to those of 9 other
members of the same laboratory and from 3 outside laboratories. Application of
two conventional statistical tests and a newly developed test for anomalous
patterns in the triplicate data commonly produced in such research to various
data sets reported by the RTS resulted in repeated rejection of the hypotheses
(often at p-levels well below 0.001) that anomalous patterns in his data may
have occurred by chance. This analysis emphasizes the importance of access to
raw data that form the bases of publications, reports and grant applications in
order to evaluate the correctness of the conclusions, as well as the utility of
methods for detecting anomalous, especially fabricated, numerical results.


title:
One-dimensional magnetism in one-dimensional metallic chains in bulk
  MnB4

abstract:
  We have investigated from first-principles an electronic structure and
magnetism in MnB4 compound with experimentally observed orthorhombic C12/m1
structure. It is found that Mn tetra-borides (MnB4) is found to have metallic
ground state with well defined local Mn magnetic moments. This conclusion was
drawn from calculation within full potential Linear Augmented Plane Wave method
and Korringa-Kohn-Rostocker method using Disordered Local Moment Approximation.
We have shown using Lichtenstein Green function method that magnetic exchange
interactions between Mn moments are strongly ferromagnetic along 1D-chains of
Mn atoms and they are practically vanishing between the chains. The metallic
state appears to exhibit a strongly one-dimensional character since the single
metallic band show dispersion only in one reciprocal lattice dimension. Thus it
appears that MnB4 may be a perfect one-dimensional one-band Hubbard model
system. Although LSDA predicts the magnetism in this system it may well be
superconductor at low temperatures due to the correlation effects beyond mean
field like approach.


title:
Entanglement and out-of-equilibrium dynamics in holographic models of de
  Sitter QFTs

abstract:
  In this paper we study various aspects of entanglement entropy in
strongly-coupled de Sitter quantum field theories in various dimensions. We
find gravity solutions that are dual to field theories in a fixed de Sitter
background, both in equilibrium and out-of-equilibrium configurations. The
latter corresponds to the Vaidya generalization of the AdS black hole solutions
with hyperbolic topology. We compute analytically the entanglement entropy of
spherical regions and show that there is a transition when the sphere is as big
as the horizon. We also explore thermalization in time-dependent situations in
which the system evolves from a non-equilibrium state to the Bunch-Davies
state. We find that the saturation time is equal to the light-crossing time of
the sphere. This behavior is faster than random walk and suggests the existence
of free light-like degrees of freedom.


title: A Multi-wavelength Study of the Host Environment of SMBHB 4C+37.11

abstract:
  4C+37.11, at z=0.055 shows two compact radio nuclei, imaged by VLBI at 7mas
separation, making it the closest known resolved super-massive black hole
binary (SMBHB). An important question is whether this unique object is young,
caught on the way to a gravitational in-spiral and merger, or has `stalled' at
7pc. We describe new radio/optical/X-ray observations of the massive host and
its surrounding X-ray halo. These data reveal X-ray/optical channels following
the radio outflow and large scale edges in the X-ray halo. These structures are
promising targets for further study which should elucidate their relationship
to the unique SMBHB core.


title:
Accurate energy-size dependence of excitonic transitions in
  semiconductor nanocrystals and nanoplatelets using a phase jump approach

abstract:
  Accurate energy-size dependence of excitonic transitions in semiconductor
nanocrystals in the strong confinement regime using classical theoretical
approaches such as effective mass approximation, tight binding, or empirical
pseudo-potential is difficult. We propose a simple empirical expression with
three fitting parameters that accurately relates the size dependence of most
known excitonic transitions in CdSe and in InAs nanocrystals. We show that this
empirical expression can be deduced from a phase jump approach if the charge
carriers are considered to travel on the atomic lattice of the nanocrystal and
gain energy upon bouncing at the nanoparticle boundaries. This empirical
expression is also tested on the atomically flat CdSe nanoplatelets without any
adjustment of the parameters obtained with the CdSe spherical nanocrystals, and
provides an estimation of the CdSe nanoplatelets thickness that matches exactly
the experimental observations. These results suggest that a phase shift
approach could be useful to describe the electronic transitions in
semiconductor nanocrystals.


title: Good and bad points in scales

abstract:
  We address three questions raised by Cummings and Foreman regarding a model
of Gitik and Sharon. We first analyze the PCF-theoretic structure of the
Gitik-Sharon model, determining the extent of good and bad scales. We then
classify the bad points of the bad scales existing in both the Gitik-Sharon
model and other models containing bad scales. Finally, we investigate the ideal
of subsets of singular cardinals of countable cofinality carrying good scales.


title: Long range order in a hard disk model in statistical mechanics

abstract:
  We model two-dimensional crystals by a configuration space in which every
admissible configuration is a hard disk configuration and a perturbed version
of some triangular lattice with side length one. In this model we show that,
under the uniform distribution, expected configurations in a given box are
arbitrarily close to some triangular lattice whenever the particle density is
chosen sufficiently high. This choice can be made independent of the box size.


title:
Equal-time Consistency Relations in the Large-Scale Structure of the
  Universe

abstract:
  We discuss the consistency relations involving the soft limit of the (n +
1)-correlator functions of dark matter at equal times and their consequences
for the halo model.


title:
Scanning wire beam position monitor for alignment of a high brightness
  inverse-Compton x-ray source

abstract:
  The Free-Electron Laser Laboratory at the University of Hawai`i has
constructed and tested a scanning wire beam position monitor to aid the
alignment and optimization of a high spectral brightness inverse-Compton
scattering x-ray source. X-rays are produced by colliding the 40 MeV electron
beam from a pulsed S-band linac with infrared laser pulses from a mode-locked
free-electron laser driven by the same electron beam. The electron and laser
beams are focused to 60 {\mu}m diameters at the interaction point to achieve
high scattering efficiency. This wire-scanner allows for high resolution
measurements of the size and position of both the laser and electron beams at
the interaction point to verify spatial coincidence. Time resolved measurements
of secondary emission current allow us to monitor the transverse spatial
evolution of the e-beam throughout the duration of a 4 {\mu}s macro-pulse while
the laser is simultaneously profiled by pyrometer measurement of the occulted
infrared beam. Using this apparatus we have demonstrated that the electron and
laser beams can be co-aligned with a precision better than 10 {\mu}m as
required to maximize x-ray yield.


title:
Static magnetic moments revealed by muon spin relaxation and
  thermodynamic measurements in quantum spin ice Yb$_2$Ti$_2$O$_7$

abstract:
  We present muon spin relaxation ($\mu$SR) and specific-heat versus
temperature $C(T)$ measurements on polycrystalline and single-crystal samples
of the pyrochlore magnet Yb$_2$Ti$_2$O$_7$. $C(T)$ exhibits a sharp peak at a
$T_\mathrm{C}$ of 0.21 and 0.26~K for the single-crystal and polycrystalline
samples respectively. For both samples, the magnetic entropy released between
50~mK and 30~K amounts to $R\ln2$ per Yb. At temperatures below $T_\mathrm{C}$
we observe a steep drop in the asymmetry of the zero-field $\mu$SR time spectra
at short time scales, as well as a decoupling of the muon spins from the
internal field in longitudinal magnetic fields of $\leq0.25$~T for both the
polycrystalline and single-crystal samples. These muon data are indicative of
static magnetic moments. Our results are consistent with the onset of
long-range magnetic order in both forms of Yb$_2$Ti$_2$O$_7$.


title:
ITLinQ: A New Approach for Spectrum Sharing in Device-to-Device
  Communication Systems

abstract:
  We consider the problem of spectrum sharing in device-to-device communication
systems. Inspired by the recent optimality condition for treating interference
as noise, we define a new concept of "information-theoretic independent sets"
(ITIS), which indicates the sets of links for which simultaneous communication
and treating the interference from each other as noise is
information-theoretically optimal (to within a constant gap). Based on this
concept, we develop a new spectrum sharing mechanism, called
"information-theoretic link scheduling" (ITLinQ), which at each time schedules
those links that form an ITIS. We first provide a performance guarantee for
ITLinQ by characterizing the fraction of the capacity region that it can
achieve in a network with sources and destinations located randomly within a
fixed area. Furthermore, we demonstrate how ITLinQ can be implemented in a
distributed manner, using an initial 2-phase signaling mechanism which provides
the required channel state information at all the links. Through numerical
analysis, we show that distributed ITLinQ can outperform similar
state-of-the-art spectrum sharing mechanisms, such as FlashLinQ, by more than a
100% of sum-rate gain, while keeping the complexity at the same level. Finally,
we discuss a variation of the distributed ITLinQ scheme which can also
guarantee fairness among the links in the network and numerically evaluate its
performance.


title: Electron Transport Properties of Composite Ferroelectrics

abstract:
  We study electron transport in composite ferroelectrics --- materials
consisting of metallic grains embedded in a ferroelectric matrix. Due to its
complex tunable morphology the thermodynamic properties of these materials can
be essentially different from bulk or thin-film ferroelectrics. We calculate
the conductivity of composite ferroelectrics by taking into account the
interplay between charge localization, multiple grain boundaries, strong
Coulomb repulsion, and ferroelectric order parameter. We show that the
ferroelectricity plays a crucial role on the temperature behavior of the
conductivity in the vicinity of the ferroelectric-paraelectric transition.


title: Intrinsic graphene field effect transistor on amorphous carbon films

abstract:
  Fabrication of graphene field effect transistor is described which uses an
intrinsic graphene on the surface of as deposited hydrogenated amorphous carbon
films. Ambipolar characteristic has been demonstrated typical for graphene
devices, which changes to unipolar characteristic if the surface graphene was
etched in oxygen plasma. Because amorphous carbon films can be growth easily,
with unlimited dimensions and no transfer of graphene is necessary, this can
open new perspective for graphene electronics.


title:
Entanglement genesis by ancilla-based parity measurement in 2D circuit
  QED

abstract:
  We present an indirect two-qubit parity meter in planar circuit quantum
electrodynamics, realized by discrete interaction with an ancilla and a
subsequent projective ancilla measurement with a dedicated, dispersively
coupled resonator. Quantum process tomography and successful entanglement by
measurement demonstrate that the meter is intrinsically quantum non-demolition.
Separate interaction and measurement steps allow commencing subsequent data
qubit operations in parallel with ancilla measurement, offering time savings
over continuous schemes.


title:
A Balloon-borne Measurement of High Latitude Atmospheric Neutrons Using
  a LiCAF Neutron Detector

abstract:
  PoGOLino is a scintillator-based neutron detector. Its main purpose is to
provide data on the neutron flux in the upper stratosphere at high latitudes at
thermal and nonthermal energies for the PoGOLite instrument. PoGOLite is a
balloon borne hard X-ray polarimeter for which the main source of background
stems from high energy neutrons. No measurements of the neutron environment for
the planned flight latitude and altitude exist. Furthermore this neutron
environment changes with altitude, latitude and solar activity, three variables
that will vary throughout the PoGOLite flight. PoGOLino was developed to study
the neutron environment and the influences from these three variables upon it.
PoGOLino consists of two Europium doped Lithium Calcium Aluminium Fluoride
(Eu:LiCAF) scintillators, each of which is sandwiched between 2 Bismuth
Germanium Oxide (BGO) scintillating crystals, which serve to veto signals
produced by gamma-rays and charged particles. This allows the neutron flux to
be measured even in high radiation environments. Measurements of neutrons in
two separate energy bands are achieved by placing one LiCAF detector inside a
moderating polyethylene shield while the second detector remains unshielded.
The PoGOLino instrument was launched on March 20th 2013 from the Esrange Space
Center in Northern Sweden to an altitude of 30.9 km. A description of the
detector design and read-out system is presented. A detailed set of simulations
of the atmospheric neutron environment performed using both PLANETOCOSMICS and
Geant4 will also be described. The comparison of the neutron flux measured
during flight to predictions based on these simulations will be presented and
the consequences for the PoGOLite background will be discussed.


title: Quantum corrections to scalar field dynamics in a slow-roll space-time

abstract:
  We consider the dynamics of a quantum scalar field in the background of a
slow-roll inflating Universe. We compute the one-loop quantum corrections to
the field and Friedmann equation of motion, in both a 1PI and a 2PI expansion,
to leading order in slow-roll. Generalizing the works of [1-3], we then solve
these equations to compute the effect on the primordial power spectrum, for the
case of a self-interacting inflaton and a self-interacting spectator field. We
find that for the inflaton the corrections are negligible due to the smallness
of the coupling constant despite the large IR enhancement of the loop
contributions. For a curvaton scenario, on the other hand, we find tension in
using the 1PI loop corrections, which may indicate that the quantum corrections
could be non-perturbatively large in this case, thus requiring resummation.


title: The Steklov spectrum of surfaces: asymptotics and invariants

abstract:
  We obtain precise asymptotics for the Steklov eigenvalues on a compact
Riemannian surface with boundary. It is shown that the number of connected
components of the boundary, as well as their lengths, are invariants of the
Steklov spectrum. The proofs are based on pseudodifferential techniques for the
Dirichlet-to-Neumann operator and on a number-theoretic argument.


title: Extended Lyman-alpha emission from a high-z DLA at z=3.115

abstract:
  We searched for star formation activity associated with high-z Damped
Lyman-alpha systems (DLAs) with Subaru telescope. We used a set of narrow-band
(NB) filters whose central wavelengths correspond to the redshifted Lyman-alpha
emission lines of targeted DLA absorbers at 3<z<4.5. We detected one apparent
NB-excess object located 3.80 arcsec (~28kpc) away from the quasar SDSS
J031036.84+005521.7. Follow-up spectroscopy revealed an asymmetric Lyman-alpha
emission at z_em=3.115+/-0.003, which perfectly matches the sub-DLA trough at
z_abs=3.1150 with logN(HI)/cm^-2=20.05. The Lyman-alpha luminosity is estimated
to be L(LyA)=1.07x10^42 erg s^-1, which corresponds to a star formation rate of
0.97 M_\odot yr^-1. Interestingly, the detected Lyman-alpha emission is
spatially extended with a sharp peak. The large extent of the Lyman-alpha
emission is remarkably one-sided toward the quasar line-of-sight, and is
redshifted. The observed spatially asymmetric surface brightness profile can be
qualitatively explained by a model of a DLA host galaxy, assuming a galactic
outflow and a clumpy distribution of HI clouds in the circumgalactic medium.
This large Lyman-alpha extension, which is similar to those found in Rauch et
al. (2008), could be the result of complicated anisotropic radiative transfer
through the surrounding neutral gas embedded in the DLA.


title: The symplectic arc algebra is formal

abstract:
  We prove a formality theorem for the Fukaya categories of the symplectic
manifolds underlying symplectic Khovanov cohomology, over fields of
characteristic zero. The key ingredient is the construction of a degree one
Hochschild cohomology class on a Floer A-infinity algebra associated to the
(k,k)-nilpotent slice Y, obtained by counting holomorphic discs which satisfy a
suitable conormal condition at infinity in a partial compactification of Y. The
partial compactification is obtained as the Hilbert scheme of a partial
compactification of a Milnor fibre. A sequel to this paper will prove formality
of the symplectic cup and cap bimodules, and infer that symplectic Khovanov
cohomology and Khovanov cohomology have the same total rank over characteristic
zero fields.


title: Superdescendants of the D1D5 CFT and their dual 3-charge geometries

abstract:
  We describe how to obtain the gravity duals of semiclassical states in the
D1-D5 CFT that are superdescendants of a class of RR ground states. On the
gravity side, the configurations we construct are regular and asymptotically
reproduce the 3-charge D1-D5-P black hole compactified on $S^1\times T^4$. The
geometries depend trivially on the $T^4$ directions but non-trivially on the
remaining 6D space. In the decoupling limit, they reduce to asymptotically
AdS$_3 \times S^3 \times T^4$ spaces that are dual to CFT states obtained by
acting with (exponentials of) the operators of the superconformal algebra. As
explicit examples, we generalise the solution first constructed in
arXiv:1306.1745 and discuss another class of states that have a more
complicated dual geometry. By using the free orbifold description of the CFT we
calculate the average values for momentum and the angular momenta of these
configurations. Finally we compare the CFT results with those obtained in the
bulk from the asymptotically $M^{1,4} \times S^1\times T^4$ region.


title: CKM benchmarks for electron EDM experiments

abstract:
  All current experiments searching for an electron EDM d_e are performed with
atoms and diatomic molecules. Motivated by significant recent progress in
searches for an EDM-type signal in diatomic molecules with an uncompensated
electron spin, we provide an estimate for the expected signal in the Standard
Model due to the CKM phase. We find that the main contribution originates from
the effective electron-nucleon operator $\bar{e} i\gamma_5 e \bar{N}N$, induced
by a combination of weak and electromagnetic interactions at
$O(G_F^2\alpha^2)$, and not by the CKM-induced electron EDM itself. When the
resulting atomic P,T-odd mixing is interpreted as an {\it equivalent} electron
EDM, this estimate leads to the benchmark $d_e^{equiv}(CKM) \sim 10^{-38}$ ecm.


title:
An approach to intersection theory on singular varieties using motivic
  complexes

abstract:
  We introduce techniques of Suslin, Voevodsky, and others into the study of
singular varieties. Our approach is modeled after Goresky-MacPherson
intersection homology. We provide a formulation of perversity cycle spaces
leading to perversity homology theory and a companion perversity cohomology
theory based upon generalized cocycle spaces. These theories lead to conditions
on pairs of cycles which can be intersected and a suitable equivalence relation
on cocycles/cycles enabling pairings on equivalence classes. We establish
suspension and splitting theorems, as well as a localization property. Some
examples of intersections on singular varieties are computed.


title:
Universal symmetry-protected topological invariants for
  symmetry-protected topological states

abstract:
  Symmetry-protected topological (SPT) states are short-range entangled states
with a symmetry G. They belong to a new class of quantum states of matter which
are classified by the group cohomology $H^{d+1}(G,\mathbb{R}/\mathbb{Z})$ in
d-dimensional space. In this paper, we propose a class of symmetry- protected
topological invariants that may allow us to fully characterize SPT states with
a symmetry group G (ie allow us to measure the cocycles in
$H^{d+1}(G,\mathbb{R}/\mathbb{Z})$ that characterize the SPT states). We give
an explicit and detailed construction of symmetry-protected topological
invariants for 2+1D SPT states. Such a construction can be directly generalized
to other dimensions.


title:
Periodic solutions of semi-explicit differential-algebraic equations
  with time-dependent constraints

abstract:
  In this paper we investigate the properties of the set of T-periodic
solutions of semi-explicit parametrized Differential-Algebraic Equations with
non-autonomous constraints of a particular type. We provide simple, degree
theoretic conditions for the existence of branches of T-periodic solutions of
the considered equations. Our approach is based on topological arguments about
differential equations on implicitly defined manifolds, combined with
elementary facts of matrix analysis.


title:
Water Adsorption at the Tetrahedral Titania Surface Layer of
  SrTiO$_3$(110)-(4$\times$1)

abstract:
  The interaction of water with oxide surfaces is of great interest for both
fundamental science and applications. We present a combined theoretical
[density functional theory (DFT)] and experimental [Scanning Tunneling
Microscopy (STM), photoemission spectroscopy (PES)] study of water interaction
with the two-dimensional titania overlayer that terminates the
SrTiO$_3$(110)-(4$\times$1) surface and consists of TiO$_4$ tetrahedra. STM,
core-level and valence band PES show that H$_2$O neither adsorbs nor
dissociates on the stoichiometric surface at room temperature, while it
dissociates at oxygen vacancies. This is in agreement with DFT calculations,
which show that the energy barriers for water dissociation on the
stoichiometric and reduced surfaces are 1.7 and 0.9 eV, respectively. We
propose that water weakly adsorbs on two-dimensional, tetrahedrally coordinated
overlayers.


title:
QUADRO: A supervised dimension reduction method via Rayleigh quotient
  optimization

abstract:
  We propose a novel Rayleigh quotient based sparse quadratic dimension
reduction method - named QUADRO (Quadratic Dimension Reduction via Rayleigh
Optimization) - for analyzing high- dimensional data. Unlike in the linear
setting where Rayleigh quotient optimization coincides with classification,
these two problems are very different under nonlinear settings. In this paper,
we clarify this difference and show that Rayleigh quotient optimization may be
of independent scientific interests. One major challenge of Rayleigh quotient
optimization is that the variance of quadratic statistics involves all fourth
cross-moments of predictors, which are infeasible to compute for
high-dimensional applications and may accumulate too many stochastic errors.
This issue is resolved by considering a family of elliptical models. Moreover,
for heavy-tail distributions, robust estimates of mean vectors and covariance
matrices are employed to guarantee uniform convergence in estimating
nonpolynomially many parameters, even though only the fourth moments are
assumed. Methodologically, QUADRO is based on elliptical models which allow us
to formulate the Rayleigh quotient maximization as a convex optimization
problem. Computationally, we propose an efficient linearized augmented
Lagrangian method to solve the constrained optimization problem. Theoretically,
we provide explicit rates of convergence in terms of Rayleigh quotient under
both Gaussian and general elliptical models. Thorough numerical results on both
synthetic and real datasets are also provided to back up our theoretical
results.


title:
What is the probability that a random integral quadratic form in $n$
  variables is isotropic?

abstract:
  We show that the density of quadratic forms in $n$ variables over ${\mathbb
Z}_p$ that are isotropic is a rational function in $p$, where the rational
function is independent of $p$, and we determine this rational function
explicitly. As a consequence, for each $n$, we determine the probability that a
random integral quadratic form in $n$ variables is isotropic. In particular, we
show that the probability that a random integral quaternary quadratic form is
isotropic is $\approx 97.0\%$, in the case where the coefficients of the
quadratic form are independently and uniformly distributed in the range
$[-X,X]$ with $X\to\infty$. When random integral quaternary quadratic forms are
chosen with respect to the Gaussian Orthogonal Ensemble (GOE), the probability
of isotropy increases to $\approx 98.3\%$.


title:
Experimental investigation of the trachea oscillation and its role in
  the pitch production

abstract:
  Several experiments have been performed to investigate the mechanical
vibrations associated with trachea and larynx when Italian vowels are emitted.
The mechanical measurements have been made by using two laser Doppler
vibrometers (based on the well-known not-invasive optical measurement
technique) coupled with the acoustic field measured by high-quality certified
microphones. The recorded signals are analyzed by using well-established
methods in time and frequency domains. The signals of the mechanical vibrations
along the trachea and the larynx are compared with those of the acoustic ones.
Focusing the attention of the signals' onsets, we can observe an upward
propagation of the mechanical vibrations for which it is possible to estimate a
delay between the traces. We observe that the mechanical oscillations at the
trachea start before the larynx and acoustic oscillations. Moreover these
tracheal oscillations are self-oscillations in time and are associated with the
pitch production, indicating a further hydrodynamic instability at trachea.
This leads to new insights in the mechanism controlling the pitch in the
speech.


title: A vanishing theorem for log canonical pairs after De Fernex-Ein

abstract:
  We extend the main vanishing theorem in a paper of de Fernex and Ein to
singular varieties without assuming locally complete intersection.


title:
A Mathematica Package for Calculation of One-Loop Penguins in FCNC
  Processes

abstract:
  In this work, we present a Mathematica package Peng4BSM@LO which calculates
the contributions to the Wilson Coefficients of certain effective operators
originating from the one-loop penguin Feynman diagrams. Both vector and scalar
external legs are considered. The key feature of our package is the ability to
find the corresponding expressions in almost any New Physics model which
extends the SM and has no flavour changing neutral current (FCNC) transitions
at the tree level.


title:
Long division unites - long union divides, a model for social network
  evolution

abstract:
  A remarkable phenomenon in the time evolution of many networks such as
cultural, political, national and economic systems, is the recurrent transition
between the states of union and division of nodes. In this work, we propose a
phenomenological modeling, inspired by the maxim "long union divides and long
division unites", in order to investigate the evolutionary characters of these
networks composed of the entities whose behaviors are dominated by these two
events. The nodes are endowed with quantities such as identity, ingredient,
richness (power), openness (connections), age, distance, interaction etc. which
determine collectively the evolution in a probabilistic way. Depending on a
tunable parameter, the time evolution of this model is mainly an alternative
domination of union or division state, with a possible state of final union
dominated by one single node.


title: Simplices in the Endomorphism Semiring of a Finite Chain

abstract:
  We establish new results concerning endomorphisms of a finite chain if the
cardinality of the image of such endomorphism is no more than some fixed
number. The semiring of all such endomorphisms can be seen as a simplex whose
vertices are the constant endomorphisms. We explore the properties of these
simplices.


title: On q-algebraic equations and their power series solutions

abstract:
  We study the existence of formal power series solutions to q-algebraic
equations. When a solution exists, we give a sufficient condition on the
equation for this solution to have a positive radius of convergence. We
emphasize on the case where the solution is divergent, giving a sharp estimate
on the growth of the coefficients. As a consequence, we obtain a bound on the
q-Gevrey order of the formal solution, which is optimal in some cases. Various
examples illustrate our main results.


title: Composable Languages for Bioinformatics: The NYoSh experiment

abstract:
  Language workbenches are software engineering tools that help domain experts
develop solutions to various classes of problems. Some of these tools focus on
non-technical users and provide languages to help organize knowledge while
other workbenches provide means to create new programming languages. A key
advantage of language workbenches is that they support the composition of
independently developed languages. This capability is useful when developing
programs that can benefit from different levels of abstraction. We reasoned
that language workbenches could be useful to develop bioinformatics software
solutions. In order to evaluate the potential of language workbenches in
bioinformatics, we tested a prominent workbench by developing an alternative to
shell scripting. While shell scripts are widely used in bioinformatics to
automate computational analysis, existing scripting languages do not provide
many of the features present in modern programming languages. We report on our
design of NYoSh (Not Your ordinary Shell). NYoSh was implemented as a
collection of languages that can be composed to write programs as expressive
and concise as shell scripts. NYoSh offers a concrete illustration of the
advantages that language workbench technologies can bring to bioinformatics.
For instance, NYoSh scripts can be edited with an environment-aware editor that
provides semantic error detection and can be compiled interactively with an
automatic build and deployment system. In contrast to shell scripts, NYoSh
scripts can be written in a modern development environment, supporting context
dependent intentions and can be extended seamlessly with new abstractions and
language constructs. We demonstrate language extension and composition by
presenting a tight integration of NYoSh scripts with the GobyWeb system. The
NYoSh Workbench prototype is distributed at http://nyosh.campagnelab.org


title:
Modelling Gamma Ray Emission and Pair Production in High-Intensity
  Laser-Matter Interactions

abstract:
  In high-intensity (> 10^21W/cm^2) laser-matter interactions gamma-ray photon
emission by the electrons can strongly affect the electron's dynamics and
copious numbers of electron-positron pairs can be produced by the emitted
photons. We show how these processes can be included in simulations by coupling
a Monte-Carlo algorithm describing the emission to a particle-in-cell code. The
Monte-Carlo algorithm includes quantum corrections to the photon emission,
which we show must be included if the pair production rate is to be correctly
determined. The accuracy, convergence and energy conservation properties of the
Monte-Carlo algorithm are analysed in simple test problems.


title: Bayesian Discovery of Threat Networks

abstract:
  A novel unified Bayesian framework for network detection is developed, under
which a detection algorithm is derived based on random walks on graphs. The
algorithm detects threat networks using partial observations of their activity,
and is proved to be optimum in the Neyman-Pearson sense. The algorithm is
defined by a graph, at least one observation, and a diffusion model for threat.
A link to well-known spectral detection methods is provided, and the
equivalence of the random walk and harmonic solutions to the Bayesian
formulation is proven. A general diffusion model is introduced that utilizes
spatio-temporal relationships between vertices, and is used for a specific
space-time formulation that leads to significant performance improvements on
coordinated covert networks. This performance is demonstrated using a new
hybrid mixed-membership blockmodel introduced to simulate random covert
networks with realistic properties.

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


title: Random Matrix Spectra as a Time Series

abstract:
  Spectra of ordered eigenvalues of finite Random Matrices are interpreted as a
time series. Dataadaptive techniques from signal analysis are applied to
decompose the spectrum in clearly differentiated trend and fluctuation modes,
avoiding possible artifacts introduced by standard unfolding techniques. The
fluctuation modes are scale invariant and follow different power laws for
Poisson and Gaussian ensembles, which already during the unfolding allows to
distinguish the two cases.


title:
Linking accretion flow and particle acceleration in jets - II.
  Self-similar jet models with full relativistic MHD gravitational mass

abstract:
  We present a new, semi-analytic formalism to model the acceleration and
collimation of relativistic jets in a gravitational potential. The
gravitational energy density includes the kinetic, thermal, and electromagnetic
mass contributions. The solutions are close to self-similar throughout the
integration, from very close to the black hole to the region where gravity is
unimportant. The field lines are tied to the conditions very close to the
central object and eventually overcollimate, possibly leading to a collimation
shock. This collimation shock could provide the conditions for diffusive shock
acceleration, leading to the observed electron populations with a power-law
energy distribution in jets.
  We provide the derivation, a detailed analysis of a solution, and describe
the effects the parameters have on the properties of the solutions, such as the
Lorentz factor and location of the collimation shock. We also discuss the
deviations from self-similarity.
  By comparing the new gravity term with the gravity term obtained from a
non-relativistic formalism in a previous work, we show they are equivalent in
the non-relativistic limit. This equivalence shows the approach taken in that
work is valid and allows us to comment on its limitations.


title: Fusion: A general framework for hierarchical tilings

abstract:
  One well studied way to construct quasicrystalline tilings is via
inflate-and-subdivide (a.k.a. substitution) rules. These produce self-similar
tilings--the Penrose, octagonal, and pinwheel tilings are famous examples. We
present a different model for generating hierarchical tilings we call "fusion
rules". Inflate-and-subdivide rules are a special case of fusion rules, but
general fusion rules are more flexible and allow for defects, changes in
geometry, and even constrained randomness. A condition that produces
homogeneous structures and a method for computing frequency for fusion tiling
spaces are discussed.


title:
Constraints on Jones transmission matrices from time-reversal invariance
  and discrete spatial symmetries

abstract:
  Optical spectroscopies are most often used to probe dynamical correlations in
materials, but they are also a probe of symmetry. Polarization anisotropies are
of course sensitive to structural anisotropies, but have been much less used as
a probe of more exotic symmetry breakings in ordered states. In this paper a
Jones transfer matrix formalism is discussed to infer the existence of exotic
broken symmetry states of matter from their electrodynamic response for a full
complement of possible broken symmetries including reflection, rotation,
rotation-reflection, inversion, and time-reversal. A specific condition to
distinguish the case of macroscopic time-reversal symmetry breaking is
particularly important as in a dynamical experiment like optics, one must
distinguish $reciprocity$ from time-reversal symmetry as dissipation violates
strict time-reversal symmetry of an experiment. Different forms of reciprocity
can be distinguished, but only one is a sufficient (but not necessary)
condition for macroscopic time-reversal symmetry breaking. I show the
constraints that a Jones matrix develops under the presence or absence of such
symmetries. These constraints typically appear in the form of an algebra
relating matrix elements or overall constraints (transposition, unitarity,
hermiticity, normality, etc.) on the form of the Jones matrix. I work out a
number of examples including the trivial case of a ferromagnet, and the less
trivial cases of magnetoelectrics and vector and scalar spin "chiral" states. I
show that the formalism can be used to demonstrate that Kerr rotation must be
absent in time-reversal symmetric chiral materials. The formalism here is
discussed with an eye towards its use in time-domain THz spectroscopy in
transmission, but with small modifications it is more generally applicable.


title: EM for phylogenetic topology reconstruction on non-homogeneous data

abstract:
  Background: The reconstruction of the phylogenetic tree topology of four taxa
is, still nowadays, one of the main challenges in phylogenetics. Its
difficulties lie in considering not too restrictive evolutionary models, and
correctly dealing with the long-branch attraction problem. The correct
reconstruction of 4-taxon trees is crucial for making quartet-based methods
work and being able to recover large phylogenies.
  Results: In this paper we consider an expectation-maximization method for
maximizing the likelihood of (time nonhomogeneous) evolutionary Markov models
on trees. We study its success on reconstructing 4-taxon topologies and its
performance as input method in quartet-based phylogenetic reconstruction
methods such as QFIT and QuartetSuite. Our results show that the method
proposed here outperforms neighbor-joining and the usual (time-homogeneous
continuous-time) maximum likelihood methods on 4-leaved trees with
among-lineage instantaneous rate heterogeneity, and perform similarly to usual
continuous-time maximum-likelihood when data satisfies the assumptions of both
methods.
  Conclusions: The method presented in this paper is well suited for
reconstructing the topology of any number of taxa via quartet-based methods and
is highly accurate, specially regarding largely divergent trees and time
nonhomogeneous data.


title:
Fundamental stellar parameters and metallicities from Bayesian
  spectroscopy. Application to low- and high-resolution spectra

abstract:
  We present a unified framework to derive fundamental stellar parameters by
combining all available observational and theoretical information for a star.
The algorithm relies on the method of Bayesian inference, which for the first
time directly integrates the spectroscopic analysis pipeline based on the
global spectrum synthesis and allows for comprehensive and objective error
calculations given the priors. Arbitrary input datasets can be included into
our analysis and other stellar quantities, in addition to stellar age,
effective temperature, surface gravity, and metallicity, can be computed on
demand. We lay out the mathematical framework of the method and apply it to
several observational datasets, including high- and low-resolution spectra
(UVES, NARVAL, HARPS, SDSS/SEGUE). We find that simpler approximations for the
spectroscopic PDF, which are inherent to past Bayesian approaches, lead to
deviations of several standard deviations and unreliable errors on the same
data. By its flexibility and the simultaneous analysis of multiple independent
measurements for a star, it will be ideal to analyse and cross-calibrate the
large ongoing and forthcoming surveys, like Gaia-ESO, SDSS, Gaia and LSST.


title:
CANDELS+3D-HST: compact SFGs at z~2-3, the progenitors of the first
  quiescent galaxies

abstract:
  We analyze the star-forming and structural properties of 45 massive
(log(M/Msun)>10) compact star-forming galaxies (SFGs) at 2<z<3 to explore
whether they are progenitors of compact quiescent galaxies at z~2. The
optical/NIR and far-IR Spitzer/Herschel colors indicate that most compact SFGs
are heavily obscured. Nearly half (47%) host an X-ray bright AGN. In contrast,
only about 10% of other massive galaxies at that time host AGNs. Compact SFGs
have centrally-concentrated light profiles and spheroidal morphologies similar
to quiescent galaxies, and are thus strikingly different from other SFGs. Most
compact SFGs lie either within the SFR-M main sequence (65%) or below (30%), on
the expected evolutionary path towards quiescent galaxies. These results show
conclusively that galaxies become more compact before they lose their gas and
dust, quenching star formation. Using extensive HST photometry from CANDELS and
grism spectroscopy from the 3D-HST survey, we model their stellar populations
with either exponentially declining (tau) star formation histories (SFHs) or
physically-motivated SFHs drawn from semi-analytic models (SAMs). SAMs predict
longer formation timescales and older ages ~2 Gyr, which are nearly twice as
old as the estimates of the tau models. While both models yield good SED fits,
SAM SFHs better match the observed slope and zero point of the SFR-M main
sequence. Some low-mass compact SFGs (log(M/Msun)=10-10.6) have younger ages
but lower sSFRs than that of more massive galaxies, suggesting that the
low-mass galaxies reach the red sequence faster. If the progenitors of compact
SFGs are extended SFGs, state-of-the-art SAMs show that mergers and disk
instabilities are both able to shrink galaxies, but disk instabilities are more
frequent (60% versus 40%) and form more concentrated galaxies. We confirm this
result via high-resolution hydrodynamic simulations.