title:
Decomposition of one-loop QCD amplitudes into primitive amplitudes based
  on shuffle relations

abstract:
  We present the decomposition of QCD partial amplitudes into primitive
amplitudes at one-loop level and tree level for arbitrary numbers of quarks and
gluons. Our method is based on shuffle relations. This method is purely
combinatorial and does not require the inversion of a system of linear
equations.


title: An impossibility theorem for linear symplectic circle quotients

abstract:
  We prove that when $d>2$, a $d$-dimensional symplectic quotient at the zero
level of a unitary circle representation $V$ such that $V^{\Sp^1}=\{0\}$ cannot
be $\Z$-graded regularly symplectomorphic to the quotient of a unitary
representations of a finite group.


title:
Transient processes in disordered semiconductor structures under
  dispersive transport conditions: Fractional calculus approach

abstract:
  We continue to develop a new approach to description of charge kinetics in
disordered semiconductors. It is based on fractional diffusion equations. This
article is devoted to transient processes in structures under dispersive
transport conditions. We demonstrate that this approach allows us (i) to take
into account energetic and topological types of disorder in common, (ii) to
consider transport in samples with spatial distributions of localized states,
and (iii) to describe transport in non-homogeneous materials with distributed
dispersion parameter. Using fractional approach provides some specifications in
interpretation of time-of-flight experiments in disordered semiconductors.


title: Nil-clean matrix rings

abstract:
  We characterize the nil clean matrix rings over fields. As a by product, it
is proved that the full matrix rings with coefficients in commutative nil-clean
rings are nil-clean, and we obtain a complete characterization of the finite
rank Abelian groups with nil clean endomorphism ring and the Abelian groups
with strongly nil clean endomorphism ring, respectively.


title:
SWIFT J1910.2-0546: A possible black hole binary with a retrograde spin
  or truncated disk

abstract:
  We present the first results from a long (51 ks) XMM-Newton observation of
the Galactic X-ray binary Swift J1910.2-0546 in a intermediate state, obtained
during its 2012 outburst. A clear, asymmetric iron emission line is observed
and physically motivated models are used to fully describe the emission-line
profile. Unlike other sources in their intermediate spectral states, the inner
accretion disk in Swift J1910.2-0546 appears to be truncated, with an inner
radius of \rin$=9.4^{+1.7}_{-1.3}$\rg\ at a 90% confidence limit.
Quasi-periodic oscillations are also found at approximately 4.5 and 6 hz, which
correlates well with the break frequency of the underlying broad-band noise.
Assuming that the line emission traces the ISCO, as would generally be expected
for an intermediate state, the current observation of Swift J1910.2-0546 may
offer the best evidence for a possible retrograde stellar mass black hole with
a spin parameter $a< -0.32 cJ/GM^2$ (90% confidence). Although this is an
intriguing possibility, there are also a number of alternative scenarios which
do not require a retrograde spin. For example, the inner accretion disk may be
truncated at an unusually high luminosity in this case, potentially suffering
frequent evaporation/condensation, or it could instead be persistently
evacuated through mass loss in a relativistic jet. Further observations are
required to distinguish between these different interpretations.


title:
Applications of tangent transformations to the linearization problem of
  fourth-order ordinary differential equations

abstract:
  Linearization problem of ordinary differential equations by a new set of
tangent transformations is considered in the paper. This set of transformations
allows one to extend the set of transformations applied for the linearization
problem. Criteria for fourth-order ordinary differential equations to be
linearizable are obtained in a particular case; a linearization test and
procedure for obtaining the linearizing transformations are provided in
explicit forms.


title: Top quark transverse momentum and rapidity distributions

abstract:
  I present NNLO approximate calculations, based on NNLL resummation, for top
quark differential transverse momentum and rapidity distributions. In
particular recent results are presented for top-pair production and single-top
production processes and compared to the latest experimental data from the LHC.


title: Quantum walks of interacting fermions on a cycle graph

abstract:
  Quantum walks have been employed widely to develop new tools for quantum
information processing recently. A natural quantum walk dynamics of interacting
particles can be used to implement efficiently the universal quantum
computation. In this work quantum walks of electrons on a graph are studied.
The graph is composed of semiconductor quantum dots arranged in a circle.
Electrons can tunnel between adjacent dots and interact via Coulomb repulsion,
which leads to entanglement. Fermionic entanglement dynamics is obtained and
evaluated.


title: Relativistic shear-free fluids with symmetry

abstract:
  We study the complete conformal geometry of shear-free spacetimes with
spherical symmetry and do not specify the form of the matter content. The
general conformal Killing symmetry is solved and we can explicitly exhibit the
vector. The existence of a conformal symmetry places restrictions on the model.
The conditions on the gravitational potentials are expressed as a system of
integrability conditions. Timelike sectors and inheriting conformal symmetry
vectors, which map fluid flow lines conformally onto fluid flow lines, are
generated and the integrability conditions are shown to be satisfied. As an
example, a spacetime, which is expanding and accelerating, is identified which
contains a spherically symmetric conformal symmetry.


title:
Derivation and Equilibrium Analysis of a Regularized Model for
  Electrostatic MEMS

abstract:
  In canonical models of Micro-Electro Mechanical Systems (MEMS), an event
called touch- down whereby the electrical components of the device come into
contact, is characterized by a blow up in the governing equations and a
non-physical divergence of the electric field. In the present work, we derive
novel regularized governing equations whose solutions remain finite at
touchdown and exhibit additional dynamics beyond this initial event before
eventually relaxing to new stable equilibria. We employ techniques from
variational calculus, dynamical systems and singular perturbation theory to
obtain a detailed understanding of the novel behaviors exhibited by the
regularized family of equations.


title: Inference of Network Summary Statistics Through Network Denoising

abstract:
  Consider observing an undirected network that is `noisy' in the sense that
there are Type I and Type II errors in the observation of edges. Such errors
can arise, for example, in the context of inferring gene regulatory networks in
genomics or functional connectivity networks in neuroscience. Given a single
observed network then, to what extent are summary statistics for that network
representative of their analogues for the true underlying network? Can we infer
such statistics more accurately by taking into account the noise in the
observed network edges?
  In this paper, we answer both of these questions. In particular, we develop a
spectral-based methodology using the adjacency matrix to `denoise' the observed
network data and produce more accurate inference of the summary statistics of
the true network. We characterize performance of our methodology through bounds
on appropriate notions of risk in the $L^2$ sense, and conclude by illustrating
the practical impact of this work on synthetic and real-world data.


title: Waste Not, Want Not: Why Rarefying Microbiome Data is Inadmissible

abstract:
  The interpretation of count data originating from the current generation of
DNA sequencing platforms requires special attention. In particular, the
per-sample library sizes often vary by orders of magnitude from the same
sequencing run, and the counts are overdispersed relative to a simple Poisson
model These challenges can be addressed using an appropriate mixture model that
simultaneously accounts for library size differences and biological
variability. This approach is already well-characterized and implemented for
RNA-Seq data in R packages such as edgeR and DESeq.
  We use statistical theory, extensive simulations, and empirical data to show
that variance stabilizing normalization using a mixture model like the negative
binomial is appropriate for microbiome count data. In simulations detecting
differential abundance, normalization procedures based on a Gamma-Poisson
mixture model provided systematic improvement in performance over crude
proportions or rarefied counts -- both of which led to a high rate of false
positives. In simulations evaluating clustering accuracy, we found that the
rarefying procedure discarded samples that were nevertheless accurately
clustered by alternative methods, and that the choice of minimum library size
threshold was critical in some settings, but with an optimum that is unknown in
practice. Techniques that use variance stabilizing transformations by modeling
microbiome count data with a mixture distribution, such as those implemented in
edgeR and DESeq, substantially improved upon techniques that attempt to
normalize by rarefying or crude proportions. Based on these results and
well-established statistical theory, we advocate that investigators avoid
rarefying altogether. We have provided microbiome-specific extensions to these
tools in the R package, phyloseq.


title: Testing the Manifold Hypothesis

abstract:
  The hypothesis that high dimensional data tend to lie in the vicinity of a
low dimensional manifold is the basis of manifold learning. The goal of this
paper is to develop an algorithm (with accompanying complexity guarantees) for
fitting a manifold to an unknown probability distribution supported in a
separable Hilbert space, only using i.i.d samples from that distribution. More
precisely, our setting is the following. Suppose that data are drawn
independently at random from a probability distribution $P$ supported on the
unit ball of a separable Hilbert space $H$. Let $G(d, V, \tau)$ be the set of
submanifolds of the unit ball of $H$ whose volume is at most $V$ and reach
(which is the supremum of all $r$ such that any point at a distance less than
$r$ has a unique nearest point on the manifold) is at least $\tau$. Let $L(M,
P)$ denote mean-squared distance of a random point from the probability
distribution $P$ to $M$.
  We obtain an algorithm that tests the manifold hypothesis in the following
sense.
  The algorithm takes i.i.d random samples from $P$ as input, and determines
which of the following two is true (at least one must be):
  (a) There exists $M \in G(d, CV, \frac{\tau}{C})$ such that $L(M, P) \leq C
\epsilon.$
  (b) There exists no $M \in G(d, V/C, C\tau)$ such that $L(M, P) \leq
\frac{\epsilon}{C}.$
  The answer is correct with probability at least $1-\delta$.


title: Sterile neutrinos in the 3+s scenario and solar data

abstract:
  The flatness of the SuperKamiokande neutrino electron scattering spectrum and
the apparent downturn of the charged current spectrum in the SNO data which the
Large Mixing Angle solution (LMA) to the solar neutrino problem fails to
predict are analysed in the context of an extension to the standard electroweak
model with light sterile neutrinos. It is found that a sterile neutrino which
is quasi degenerate with the active ones with $\Delta m^2_{41}=10^{-5}eV^2$ and
mixing $sin\theta_{14}=0.04$ provides a suitable improvement to the LMA data
fits.


title: Potential multiple steady-states in the long-term carbon cycle

abstract:
  In our modeling of the long-term carbon cycle we find potential multiple
steady-states in Phanerozoic climates. We include the effects of biotic
enhancement of weathering on land, organic carbon burial, oxidation of reduced
organic carbon in terrestrial sediments and the variation of biotic
productivity with temperature, finding a second stable steady-state appearing
between 20 and 50 oC. The very warm early Triassic climate as well as an
oceanic anoxic event in the late Cretaceous may be the potential candidates for
an upper temperature steady-state. Given our results, the anthropogenic driven
rise of atmospheric carbon dioxide could potentially push the climate into
tipping points to a modestly higher temperature steady-state, instead of
relaxing back to pre-anthropogenic conditions.


title:
Update of the like-sign dimuon charge asymmetry measurement from the D0
  experiment

abstract:
  The D0 Collaboration has published three measurements of the CP-violating
like-sign dimuon charge asymmetry in p-pbar collisions at the Fermilab Tevatron
collider. These measurements are significantly different from the standard
model predictions. In this presentation, we discuss the status of the final
measurement of this asymmetry and the expected improved sensitivities, using
the full 10.4 inverse-fb data sample collected during Run II, and discuss its
possible interpretations


title: A Dynamical Analysis of the Corona Borealis Supercluster

abstract:
  Using data from the Sloan Digital Sky Survey we assess the current dynamical
state of the Corona Borealis Supercluster (CSC), a highly dense and compact
supercluster at z = 0.07. The Fundamental Plane relation is used to determine
redshift independent distances to six clusters in the densest region of the
supercluster, with mean accuracy in the relative distance estimates of 4 per
cent. Peculiar velocities determined from these distance estimates indicate
that the clusters have broken from the Hubble Flow, suggesting that the CSC
likely contains two regions that have reached turnaround and are currently
undergoing gravitational collapse. These results provide the strongest
observational evidence to date that the CSC is a bound system similar to the
much more extensive Shapley Supercluster, which is the most extensive confirmed
bound supercluster yet identified in the Universe. When compared with
simulations of the CSC our results require substantially more mass than is
contained within the clusters, possibly indicating a significant inter-cluster
dark matter component. In order to facilitate comparison with studies for which
spectroscopic data are not available, an alternative analysis of the dynamics
is made using the Kormendy relation as a distance indicator. The results are
generally consistent with those of the Fundamental Plane and suggest similar
global dynamics, but we find that the relatively sparse sampling of the
clusters makes the Kormendy relation less reliable overall and more susceptible
to small systematic differences between the cluster samples.


title:
Massive Milky Way Satellites in Cold and Warm Dark Matter: Dependence on
  Cosmology

abstract:
  We investigate the claim that the largest subhaloes in high resolution
dissipationless cold dark matter (CDM) simulations of the Milky Way are
dynamically inconsistent with observations of its most luminous satellites. We
find that the inconsistency is largely attributable to the large values of
\sigma_8 and n_s adopted in the discrepant simulations producing satellites
that form too early and therefore are too dense. We find the tension between
observations and simulations adopting parameters consistent with WMAP9 is
greatly diminished making the satellites a sensitive test of CDM. We find the
Via Lactea II halo to be atypical for haloes in a WMAP3 cosmology, a
discrepancy that we attribute to its earlier formation epoch than the mean for
its mass. We also explore warm dark matter (WDM) cosmologies for 1--4 keV
thermal relics. In 1 keV cosmologies subhaloes have circular velocities at kpc
scales ~ 60% lower than their CDM counterparts, but are reduced by only 10% in
4 keV cosmologies. Since relic masses < 2-3 keV are ruled out by constraints
from the number of Milky Way satellites and Lyman-\alpha\ forest, WDM has a
minor effect in reducing the densities of massive satellites. Given the
uncertainties on the mass and formation epoch of the Milky Way, the need for
reducing the satellite densities with baryonic effects or WDM is alleviated.


title: QCD Sum Rule Analysis of Heavy Quarkonium Hybrids

abstract:
  We have studied the charmonium and bottomonium hybrid states with various
$J^{PC}$ quantum numbers in QCD sum rules. At leading order in $\alpha_s$, the
two-point correlation functions have been calculated up to dimension six
including the tri-gluon condensate and four-quark condensate. After performing
the QCD sum rule analysis, we have confirmed that the dimension six condensates
can stabilize the hybrid sum rules and allow the reliable mass predictions. We
have updated the mass spectra of the charmonium and bottomonium hybrid states
and identified that the negative-parity states with $J^{PC}=(0, 1, 2)^{-+},
1^{--}$ form the lightest hybrid supermultiplet while the positive-parity
states with $J^{PC}=(0, 1)^{+-}, (0, 1, 2)^{++}$ belong to a heavier hybrid
supermultiplet.


title: Online Learning of Dynamic Parameters in Social Networks

abstract:
  This paper addresses the problem of online learning in a dynamic setting. We
consider a social network in which each individual observes a private signal
about the underlying state of the world and communicates with her neighbors at
each time period. Unlike many existing approaches, the underlying state is
dynamic, and evolves according to a geometric random walk. We view the scenario
as an optimization problem where agents aim to learn the true state while
suffering the smallest possible loss. Based on the decomposition of the global
loss function, we introduce two update mechanisms, each of which generates an
estimate of the true state. We establish a tight bound on the rate of change of
the underlying state, under which individuals can track the parameter with a
bounded variance. Then, we characterize explicit expressions for the steady
state mean-square deviation(MSD) of the estimates from the truth, per
individual. We observe that only one of the estimators recovers the optimal
MSD, which underscores the impact of the objective function decomposition on
the learning quality. Finally, we provide an upper bound on the regret of the
proposed methods, measured as an average of errors in estimating the parameter
in a finite time.


title: Compact models with regular charge distributions

abstract:
  We model a compact relativistic body with anisotropic pressures in the
presence of an electric field. The equation of state is barotropic with a
linear relationship between the radial pressure and the energy density. Simple
exact models of the Einstein-Maxwell equations are generated. A graphical
analysis indicates that the matter and electromagnetic variables are well
behaved. In particular the proper charge density is regular for certain
parameter values at the stellar centre unlike earlier anisotropic models in the
presence of charge. We show that the electric field affects the mass of stellar
objects and the observed mass for a particular binary pulsar is regained. Our
models contain previous results of anisotropic charged matter with a linear
equation of state for special parameter values.


title:
Progress Towards an ab initio, Standard Model Calculation of Direct
  CP-Violation in K-decays

abstract:
  We discuss the RBC & UKQCD collaboration's progress towards a
first-principles calculation of direct CP-violation in the Standard Model via K
->pi pi decays. In particular we focus upon the calculation of the I=0 channel
amplitude A_0, for which obtaining physical kinematics requires more
sophisticated techniques than those used for the I=2-channel decay. We discuss
our chosen techniques along with preliminary demonstrations of their
application to simpler lattice quantities, and finally discuss our progress in
generating the large-volume, physical-pion-mass ensembles that will be used to
perform the A_0 calculation.


title:
Polarization corrections to single-particle energies studied within the
  energy-density-functional and QRPA approaches

abstract:
  Background: Models based on using perturbative polarization corrections and
mean-field blocking approximation give conflicting results for masses of odd
nuclei.
  Purpose: Systematically investigate the polarization and mean-field models,
implemented within self-consistent approaches that use identical interactions
and model spaces, so as to find reasons for the conflicts between them.
  Methods: For density-dependent interactions and with pairing correlations
included, we derive and study links between the mean-field and polarization
results obtained for energies of odd nuclei. We also identify and discuss
differences between the polarization-correction and full
particle-vibration-coupling (PVC) models. Numerical calculations are performed
for the mean-field ground-state properties of deformed odd nuclei and then
compared to the polarization corrections determined by using the approach that
conserves spherical symmetry.
  Results: We have identified and numerically evaluated self-interaction (SI)
energies that are at the origin of different results obtained within the
mean-field and polarization-correction approaches.
  Conclusions: Mean-field energies of odd nuclei are polluted by the SI
energies, and this makes them different from those obtained by using
polarization-correction methods. A comparison of both approaches allows for the
identification and determination of the SI terms, which then can be calculated
and removed from the mean-field results, giving the self-interaction-free
energies. The simplest deformed mean-field approach that does not break parity
symmetry is unable to reproduce full PVC effects.


title:
NIR Schottky Photodetectors Based on Individual Single-Crystalline GeSe
  Nanosheet

abstract:
  We have synthesized high-quality, micrometer-sized, single-crystal GeSe
nanosheets using vapor transport and deposition techniques. Photoresponse is
investigated based on mechanically exfoliated GeSe nanosheet combined with Au
contacts under a global laser irradiation scheme. The nonlinearship,
asymmetric, and unsaturated characteristics of the I-V curves reveal that two
uneven back-to-back Schottky contacts are formed. First-principles calculations
indicate that the occurrence of defects-induced in-gap defective states, which
are responsible for the slow decay of the current in the OFF state and for the
weak light intensity dependence of photocurrent. The Schottky photodetector
exhibits a marked photoresponse to NIR light illumination at a wavelength of
808 nm. The significant photoresponse and good responsitivity suggests its
potential applications as photodetectors.


title:
Angular Distribution of Electrons in Photoionization of Atoms Adsorbed
  on a Graphene Sheet

abstract:
  Within the framework of a model representing the potential of a graphene
sheet U(z) as an electro-neutral layer formed by smeared carbon atoms, the
effect of this potential on spectral characteristics of atoms adsorbed on a
graphene sheet has been studied. Since the distance between the adsorbed atom
nucleus and sheet surface significantly exceeds the radii of inner atomic
shells the potential U(z) makes influence on the continuum wave functions only.
Their behavior in the upper semi-space (z>0) and in the lower one (z<0) where
the adsorbed atom is located is defined by a jump of the logarithmic derivative
of the wave function for z=0. The photoelectron angular distributions have been
calculated for different mutual positions of the polarization vector e and the
axis Z normal to the sheet surface. It has been shown that the existence of the
electron waves reflected from the potential U(z) leads to evident asymmetry of
the angular distribution relative to the plane z=0. The experimental
observation of this effect is of great interest for photoelectron spectroscopy
of atoms localized on graphene structures.


title: Exploring the role of Leggett-Garg inequality for quantum cryptography

abstract:
  In the cryptographic context, an earlier unexplored application of the
temporal version of the Bell-type inequality is shown here in the
device-independent (DI) scenario. This is done by using the Leggett-Garg
inequality (LGI) to demonstrate the security against eavesdropping in a quantum
key distribution (QKD) scheme. This typically involves a higher dimensional
attack against which the standard BB84 protocol is insecure. For this purpose,
we invoke an appropriate form of LGI. While the key generation is done by the
usual Bennett-Brassard 1984 (BB84) method, the security check against device
attacks is provided by testing for the violation of the particular form of LGI
used here.


title:
Photocurrent characteristics of individual GeSe2 nanobelt with Schottky
  effects

abstract:
  Single crystal GeSe2 nanobelts (NBs) were successfully grown using chemical
vapor deposition techniques. The morphology and structure of the nanostructures
were characterized using scanning electron microscopy, transmission electron
microscopy, X-ray diffractometry, and Raman spectroscopy. Electronic transport
properties, photoconductive characteristics, and temperature-dependent
electronic characteristics were examined on devices made of individual GeSe2
nanobelt. Localized photoconductivity study shows that the large photoresponse
of the device primarily occurs at the metal-NB contact regions. In addition,
the electrically Schottky nature of nanobelt-Au contact and p-type conductivity
nature of GeSe2 nanobelt are extracted from the current-voltage characteristics
and spatially resolved photocurrent measurements. The high sensitivity and
quick photoresponse in the visible wavelength range indicate potential
applications of individual GeSe2 nanobelt devices in realizing optoelectronic
switches.


title: Some charged polytropic models

abstract:
  The Einstein-Maxwell equations with anisotropic pressures and electromagnetic
field are studied with a polytropic equation of state. New exact solutions to
the field equations are generated in terms of elementary functions. Special
cases of the uncharged solutions of Feroze and Siddiqui (Gen Relativ Gravit 43:
1025, 2011) and Maharaj and Mafa Takisa (Gen Relativ Gravit 44: 1419, 2012) are
recovered. We also obtain exact solutions for a neutral anisotropic gravitating
body for a polytrope from our general treatment. Graphical plots indicate that
the energy density, tangential pressure and anisotropy profiles are consistent
with earlier treatments which suggest relevance in describing relativistic
compact stars.


title:
Countering Wrapping Attack on XML Signature in SOAP Message for Cloud
  Computing

abstract:
  It is known that the exchange of information between web applications is done
by means of the SOAP protocol. Securing this protocol is obviously a vital
issue for any computer network. However, when it comes to cloud computing
systems, the sensitivity of this issue rises, as the clients of system, release
their data to the cloud. XML signature is employed to secure SOAP messages.
However, there are also some weak points that have been identified, named as
XML signature wrapping attacks, which have been categorized into four major
groups; Simple Ancestry Context Attack, Optional element context attacks,
Sibling Value Context Attack, Sibling Order Context. In this paper, two
existing methods, for referencing the signed part of SOAP Message, named as ID
referencing and XPath method, are analyzed and examined. In addition, a new
method is proposed and tested, to secure the SOAP message. In the new method,
the XML any signature wrapping attack is prevented by employing the concept of
XML digital signature on the SOAP message. The results of conducted experiments
show that the proposed method is approximately three times faster than the
XPath method and even a little faster than ID.


title: Dipole-Magnetic Photo-Recombination in Ultracold Hydrogen Plasma

abstract:
  The cross section of dipole-magnetic photodisintegration of the negative
hydrogen ion has been calculated within the framework of an effective-range
theory. The dipole-magnetic cross section of photodetachment within the very
narrow range of energy near the process threshold dominates over the
dipole-electric one. It has been shown that in ultracold hydrogen plasma at
temperatures below kT=3.29.10-4 K the dipole-magnetic photo-recombination
becomes a main mechanism of electron capture by hydrogen atoms.


title: Quantum-enhanced Phase Estimation with an Amplified Bell State

abstract:
  We propose a phase estimation protocol for optical interferometry that
employs a probe state (containing on average n photons) obtained by squeezing
each mode, separately, of a single photon path entangled Bell state. This
scheme involves a Mach-Zehnder type interferometer for which each mode is
squeezed after the first beam splitter. Information about the differential
phase is extracted using a parity detection and the resulting measurement
signal is super-resolving and supersensitive, with a minimum phase uncertainty
2/(n+1). This probe state can be generated with current technologies where n is
in the order of many thousands of photons.


title: Results on angular correlations with ALICE

abstract:
  Angular correlations are a sensitive probe of the transport properties of the
system produced in nucleus-nucleus collisions. Similar studies performed in
p-Pb collisions have recently revealed intriguing features as well. In this
article, we review the latest results on charged and identified particle
correlations obtained with the ALICE detector at the LHC in both Pb-Pb and p-Pb
events.


title: Ehrenfest Dynamics and Frictionless Cooling Methods

abstract:
  Recently introduced methods which result in shortcuts to adiabaticity,
particularly in the context of frictionless cooling, are rederived and
discussed in the framework of an approach based on Ehrenfest dynamics. This
construction provides physical insights into the emergence of the Ermakov
equation, the choice of its boundary conditions, and the use of minimum
uncertainty states as indicators of the efficiency of the procedure.
Additionally, it facilitates the extension of frictionless cooling to more
general situations of physical relevance, such as optical dipole trapping
schemes. In this context, we discuss frictionless cooling in the short-time
limit, a complementary case to the one considered in the literature, making
explicit the limitations intrinsic to the technique when the full
three-dimensional case is analyzed.


title: A maximum entropy model for opinions in social groups

abstract:
  We study how the opinions of a group of individuals determine their spatial
distribution and connectivity, through an agent-based model. The interaction
between agents is described by a Potts-like Hamiltonian in which agents are
allowed to move freely without an underlying lattice (the average network
topology connecting them is determined from the parameters). This kind of model
was derived using maximum entropy statistical inference under fixed expectation
values of certain probabilities that (we propose) are relevant to social
organization. Control parameters emerge as Lagrange multipliers of the maximum
entropy problem, and they can be associated with the level of consequence
between the personal beliefs and external opinions, and the tendency to
socialize with peers of similar or opposing views. These parameters define a
phase diagram for the social system, which we studied using Monte Carlo
Metropolis simulations. Our model presents both first and second-order phase
transitions, depending on the ratio between the internal consequence and the
interaction with others. We have found a critical value for the level of
internal consequence, below which the personal beliefs of the agents seem to be
irrelevant.


title:
Study of CP-violating charge asymmetries of single muons and like-sign
  dimuons in p pbar collisions

abstract:
  We measure the inclusive single muon charge asymmetry and the like-sign
dimuon charge asymmetry in $p \bar{p}$ collisions using the full data set of
10.4 fb$^{-1}$ collected with the D0 detector at the Fermilab Tevatron. The
standard model predictions of the charge asymmetries induced by CP violation
are small in magnitude compared to the current experimental precision, so
non-zero measurements could indicate new sources of CP violation. The
measurements differ from the standard model predictions of CP violation in
these asymmetries with a significance of 3.6 standard deviations. These results
are interpreted in a framework of $B$ meson mixing within the CKM formalism to
measure the relative width difference $\dgg$ between the mass eigenstates of
the $\Bd$ meson system, and the semileptonic charge asymmetries $\asld$ and
$\asls$ of $\Bd$ and $\Bs$ mesons respectively.


title: Zipf's law and criticality in multivariate data without fine-tuning

abstract:
  The joint probability distribution of many degrees of freedom in biological
systems, such as firing patterns in neural networks or antibody sequence
composition in zebrafish, often follow Zipf's law, where a power law is
observed on a rank-frequency plot. This behavior has recently been shown to
imply that these systems reside near to a unique critical point where the
extensive parts of the entropy and energy are exactly equal. Here we show
analytically, and via numerical simulations, that Zipf-like probability
distributions arise naturally if there is an unobserved variable (or variables)
that affects the system, e. g. for neural networks an input stimulus that
causes individual neurons in the network to fire at time-varying rates. In
statistics and machine learning, these models are called latent-variable or
mixture models. Our model shows that no fine-tuning is required, i.e. Zipf's
law arises generically without tuning parameters to a point, and gives insight
into the ubiquity of Zipf's law in a wide range of systems.


title:
Macroclumping as solution of the discrepancy between H{\alpha} and P v
  mass loss diagnostics for O-type stars

abstract:
  Recent studies of O-type stars demonstrated that discrepant mass-loss rates
are obtained when different diagnostic methods are employed - fitting the
unsaturated UV resonance lines (e.g. P v) gives drastically lower values than
obtained from the H{\alpha} emission. Wind clumping may be the main cause for
this discrepancy. In a previous paper, we have presented 3-D Monte-Carlo
calculations for the formation of scattering lines in a clumped stellar wind.
In the present paper we select five O-type supergiants (from O4 to O7) and test
whether the reported discrepancies can be resolved this way. In the first step,
the analyses start with simulating the observed spectra with Potsdam Wolf-Rayet
(PoWR) non-LTE model atmospheres. The mass-loss rates are adjusted to fit best
to the observed H{\alpha} emission lines. For the unsaturated UV resonance
lines (i.e. P v) we then apply our 3-D Monte-Carlo code, which can account for
wind clumps of any optical depths, a non-void inter-clump medium, and a
velocity dispersion inside the clumps. The ionization stratifications and
underlying photospheric spectra are adopted from the PoWR models. From fitting
the observed resonance line profiles, the properties of the wind clumps are
constrained. Our results show that with the mass-loss rates that fit H{\alpha}
(and other Balmer and He II lines), the UV resonance lines (especially the
unsaturated doublet of P v) can also be reproduced without problem when
macroclumping is taken into account. There is no need to artificially reduce
the mass-loss rates, nor to assume a sub-solar phosphorus abundance or an
extremely high clumping factor, contrary to what was claimed by other authors.
These consistent mass-loss rates are lower by a factor of 1.3 to 2.6, compared
to the mass-loss rate recipe from Vink et al. Macroclumping resolves the
previously reported discrepancy between H{\alpha} and P v mass-loss
diagnostics.


title:
Variational Formulation of Macro-Particle Models for Electromagnetic
  Plasma Simulations

abstract:
  A variational method is used to derive a self-consistent macro-particle model
for relativistic electromagnetic kinetic plasma simulations. Extending earlier
work [E. G. Evstatiev and B. A. Shadwick, J. Comput. Phys., vol. 245, pp.
376-398, 2013], the discretization of the electromagnetic Low Lagrangian is
performed via a reduction of the phase-space distribution function onto a
collection of finite-sized macro-particles of arbitrary shape and
discretization of field quantities onto a spatial grid. This approach may be
used with both lab frame coordinates or moving window coordinates; the latter
can greatly improve computational efficiency for studying some types of
laser-plasma interactions. The primary advantage of the variational approach is
the preservation of Lagrangian symmetries, which in our case leads to energy
conservation and thus avoids difficulties with grid heating. Additionally, this
approach decouples particle size from grid spacing and relaxes restrictions on
particle shape, leading to low numerical noise. The variational approach also
guarantees consistent approximations in the equations of motion and is amenable
to higher order methods in both space and time. We restrict our attention to
the 1-1/2 dimensional case (one coordinate and two momenta). Simulations are
performed with the new models and demonstrate energy conservation and low
noise.


title:
Infrared identification of high-mass X-ray binaries discovered by
  INTEGRAL

abstract:
  Since it started observing the sky, the INTEGRAL satellite has discovered new
categories of high mass X-ray binaries (HMXB) in our Galaxy. These observations
raise important questions on the formation and evolution of these rare and
short-lived objects. We present here new infrared observations from which to
reveal or constrain the nature of 15 INTEGRAL sources, which allow us to update
and discuss the Galactic HMXB population statistics. After previous photometric
and spectroscopic observing campaigns in the optical and near-infrared, new
photometry and spectroscopy was performed in the near-infrared with the SofI
instrument on the ESO/NTT telescope in 2008 and 2010 on a sample of INTEGRAL
sources. These observations, and specifically the detection of certain features
in the spectra, allow the identification of these high-energy objects by
comparison with published nIR spectral atlases of O and B stars. We present
photometric data of nine sources (IGR J10101-5654, IGR J11187-5438, IGR
J11435-6109, IGR J14331-6112, IGR J16328-4726, IGR J17200-3116, IGR
J17354-3255, IGR J17404-3655, and IGR J17586-2129) and spectroscopic
observations of 13 sources (IGR J10101-5654, IGR J11435-6109, IGR J13020-6359,
IGR J14331-6112, IGR J14488-5942, IGR J16195-4945, IGR J16318-4848, IGR
J16320-4751, IGR J16328-4726, IGR J16418-4532, IGR J17354-3255, IGR
J17404-3655, and IGR J17586-2129). Our spectroscopic measurements indicate
that: five of these objects are Oe/Be high-mass X-ray binaries (BeHMXB), six
are supergiant high-mass X-ray binaries (sgHMXB), and two are sgB[e]. From a
statistical point of view, we estimate the proportion of confirmed sgHMXB to be
42% and that of the confirmed BeHMXB to be 49%. The remaining 9% are peculiar
HMXB.


title:
Optoelectronics with electrically tunable PN diodes in a monolayer
  dichalcogenide

abstract:
  One of the most fundamental devices for electronics and optoelectronics is
the PN junction, which provides the functional element of diodes, bipolar
transistors, photodetectors, LEDs, and solar cells, among many other devices.
In conventional PN junctions, the adjacent p- and n-type regions of a
semiconductor are formed by chemical doping. Materials with ambipolar
conductance, however, allow for PN junctions to be configured and modified by
electrostatic gating. This electrical control enables a single device to have
multiple functionalities. Here we report ambipolar monolayer WSe2 devices in
which two local gates are used to define a PN junction exclusively within the
sheet of WSe2. With these electrically tunable PN junctions, we demonstrate
both PN and NP diodes with ideality factors better than 2. Under excitation
with light, the diodes show photodetection responsivity of 210 mA/W and
photovoltaic power generation with a peak external quantum efficiency of 0.2%,
promising numbers for a nearly transparent monolayer sheet in a lateral device
geometry. Finally, we demonstrate a light-emitting diode based on monolayer
WSe2. These devices provide a fundamental building block for ubiquitous,
ultra-thin, flexible, and nearly transparent optoelectronic and electronic
applications based on ambipolar dichalcogenide materials.


title: Massive spin-2 theories

abstract:
  We give an introduction to massive spin-2 theories and the problem of their
non-linear completion. We review the Boulware-Deser ghost problem and two ways
to circumvent classic no-go theorems. In turn, massive spin-2 theories are not
uniquely defined. In the case of truncated theories, we show that the
Boulware-Deser ghost may only be avoided if the derivative structure of the
theory is not tuned to be Einsteinian.


abstract:
  Surface tension profiles in vertical soap films are experimentally
investigated. Measurements are performed introducing deformable elastic objets
in the films. The shape adopted by those objects set in the film can be related
to the surface tension value at a given vertical position by numerical solving
of adapted elasticity equations. We show that the observed dependency of the
surface tension versus the vertical position in the soap film can be reproduced
by simple modeling taking into account film thickness measurements.


title: The extrema of an action principle for dissipative mechanical systems

abstract:
  A least action principle for damping motion has been previously proposed with
a Hamiltonian and a Lagrangian containing the energy dissipated by friction.
Due to the space-time nonlocality of the Lagrangian, mathematical uncertainties
persist about the appropriate variational calculus and the nature (maxima,
minima and inflection) of the stationary action. The aim of this work is to
make numerical simulation of damped motion and to compare the actions of
different paths in order to get evidence of the existence and the nature of
stationary action. The model is a small particle subject to conservative and
friction forces. Two conservative forces and three friction forces are
considered. The comparison of the actions of the perturbed paths with that of
the Newtonian path reveals the existence of extrema of action which are minima
for zero or very weak friction and shift to maxima when the motion is
overdamped. In the intermediate case, the action of the Newtonian path is
neither least nor most, meaning that the extreme feature of the Newtonian path
is lost. In this situation, however, no reliable evidence of stationary action
can be found from the simulation result.


title:
Investigating the presence of 500 um submillimeter excess emission in
  local star forming galaxies

abstract:
  Submillimeter excess emission has been reported at 500 microns in a handful
of local galaxies, and previous studies suggest that it could be correlated
with metal abundance. We investigate the presence of an excess submillimeter
emission at 500 microns for a sample of 20 galaxies from the Key Insights on
Nearby Galaxies: a Far Infrared Survey with Herschel (KINGFISH) that span a
range of morphologies and metallicities (12+log(O/H)=7.8-8.7). We probe the
far-infrared (IR) emission using images from the Spitzer Space Telescope and
Herschel Space Observatory in the wavelength range 24-500 microns. We model the
far-IR peak of the dust emission with a two-temperature modified blackbody and
measure excess of the 500 micron photometry relative to that predicted by our
model. We compare the submillimeter excess, where present, with global galaxy
metallicity and, where available, resolved metallicity measurements. We do not
find any correlation between the 500 micron excess and metallicity. A few
individual sources do show excess (10-20%) at 500 microns; conversely, for
other sources, the model overpredicts the measured 500 micron flux density by
as much as 20%, creating a 500 micron "deficit". None of our sources has an
excess larger than the calculated 1-sigma uncertainty, leading us to conclude
that there is no substantial excess at submillimeter wavelengths at or shorter
than 500 microns in our sample. Our results differ from previous studies
detecting 500 micron excess in KINGFISH galaxies largely due to new, improved
photometry used in this study.


title:
The Extremely Red, Young L Dwarf PSO J318-22: A Free-Floating
  Planetary-Mass Analog to Directly Imaged Young Gas-Giant Planets

abstract:
  We have used Pan-STARRS1 to discover an extremely red late-L dwarf, which has
(J-K)_MKO = 2.84 and (J-K)_2MASS = 2.78, making it the reddest known field
dwarf and second only to 2MASS J1207-39b among substellar companions. Near-IR
spectroscopy shows a spectral type of L7 and reveals a triangular H-band
continuum and weak alkali (K I and Na I) lines, hallmarks of low surface
gravity. Near-IR astrometry from the Hawaii Infrared Parallax Program gives a
distance of 24.6+/-1.4 pc and indicates a much fainter J-band absolute
magnitude than field L dwarfs. The position and kinematics of PSO J318-22 point
to membership in the beta Pictoris moving group. Evolutionary models give a
temperature of 1160 (-40,+30) K and a mass of 6.5 (-1.0, +1.3) Mjup, making PSO
J318-22 one of the lowest mass free-floating objects in the solar neighborhood.
This object adds to the growing list of low-gravity field L dwarfs and is the
first to be strongly deficient in methane relative to its estimated
temperature. Comparing their spectra suggests that young L dwarfs with similar
ages and temperatures can have different spectral signatures of youth. For the
two objects with well constrained ages (PSO J318-22 and 2MASS J0355+11), we
find their temperatures are ~400 K cooler than field objects of similar
spectral type but their luminosities are comparable, i.e., these young L dwarfs
are very red and unusually cool but not "underluminous." Altogether, PSO
J318-22 is the first free-floating object with the colors, magnitudes,
spectrum, luminosity, and mass that overlap the young dusty planets around HR
8799 and 2MASS J1207-39.


title:
The fragmenting past of the disk at the Galactic Center : The culprit
  for the missing red giants

abstract:
  Since 1996 we have known that the Galactic Center (GC) displays a core-like
distribution of red giant branch (RGB) stars starting at ~ 10", which poses a
theoretical problem, because the GC should have formed a segregated cusp of old
stars. This issue has been addressed invoking stellar collisions, massive black
hole binaries, and infalling star clusters, which can explain it to some
extent. Another observational fact, key to the work presented here, is the
presence of a stellar disk at the GC. We postulate that the reason for the
missing stars in the RGB is closely intertwined with the disk formation, which
initially was gaseous and went through a fragmentation phase to form the stars.
Using simple analytical estimates, we prove that during fragmentation the disk
developed regions with densities much higher than a homogeneous gaseous disk,
i.e. "clumps", which were optically thick, and hence contracted slowly. Stars
in the GC interacted with them and in the case of RGB stars, the clumps were
dense enough to totally remove their outer envelopes after a relatively low
number of impacts. Giant stars in the horizontal branch (HB), however, have
much denser envelopes. Hence, the fragmentation phase of the disk must have had
a lower impact in their distribution, because it was more difficult to remove
their envelopes. We predict that future deeper observations of the GC should
reveal less depletion of HB stars and that the released dense cores of RGB
stars will still be populating the GC.


title: Higgs Couplings and Naturalness in $\lambda$-SUSY

abstract:
  We study Higgs boson couplings in the large-$\lambda$ version of the
Next-to-Minimal Supersymmetric Standard Model, known as $\lambda$-SUSY. We find
that the predicted deviations from the Standard Model (SM) in these couplings
are inversely correlated with the amount of fine-tuning needed to accommodate a
126 GeV Higgs. In the most natural regions of parameter space, the 126 GeV
Higgs has large admixtures of both the SM-singlet and the non-SM Higgs doublet
scalars, and such regions are already ruled out by the LHC. Future improvements
in the Higgs coupling measurements will either discover deviations from the SM,
or put further stress on naturalness in $\lambda$-SUSY.


title: Herschel survey of brown dwarf disks in Rho Ophiuchi

abstract:
  Recent observations of the Rho Ophiuchi cluster with the Herschel Space
Observatory allow us to probe the spectral energy distribution (SED) of the
brown dwarf population in the far-IR, where the disk emission peaks. We
performed aperture photometry at 70, 100, and 160 micron, and constructed SEDs
for all previously known brown dwarfs detected. These were complemented with
ancillary photometry at shorter wavelengths. We compared the observed SEDs to a
grid of synthetic disks produced with the radiative transfer code MCFOST, and
used the relative figure of merit estimated from the Bayesian inference of each
disk parameter to analyse the structural properties. We detected 12 Class II
brown dwarfs with Herschel, which corresponds to one-third of all currently
known brown dwarf members of Rho Ophiuchi. We do not detect any of the known
Class III brown dwarfs. Comparison to models reveals that the disks are best
described by an inner radius between 0.01 and 0.07 AU, and a flared disk
geometry with a flaring index between 1.05 and 1.2. Furthermore, we can exclude
values of the disk scale-height lower than 10 AU (measured at a fiducial radius
of 100 AU). We combined the Herschel data with recent ALMA observations of the
brown dwarf GY92 204 (ISO-Oph 102), and by comparing its SED to the same grid
of disk models, we derived an inner disk radius of 0.035 AU, a scale height of
15 AU with a flaring index of beta~1.15, an exponent for dust settling of -1.5,
and a disk mass of 0.001 MSun. This corresponds to a disk-to-central object
mass ratio of ~1%. The structural parameters constrained by the extended SED
coverage (inner radius and flaring index) show a narrow distribution for the 11
young brown dwarfs detected in Rho Ophiuchi, suggesting that these objects
share the same disk evolution and, perhaps, formation.


title: Polarized Parton Distributions at an Electron-Ion Collider

abstract:
  We study the potential impact of inclusive deep-inelastic scattering data
from a future electron-ion collider (EIC) on longitudinally polarized parton
distribution (PDFs). We perform a PDF determination using the NNPDF
methodology, based on sets of deep-inelastic EIC pseudodata, for different
realistic choices of the electron and proton beam energies. We compare the
results to our current polarized PDF set, NNPDFpol1.0, based on a fit to
fixed-target inclusive DIS data. We show that the uncertainties on the first
moments of the polarized quark singlet and gluon distributions are
substantially reduced in comparison to NNPDFpol1.0, but also that more
measurements may be needed to ultimately pin down the size of the gluon
contribution to the nucleon spin.


title:
Synchrotron and inverse-Compton emission from blazar jets - IV. BL Lac
  type blazars and the physical basis for the blazar sequence

abstract:
  In this paper we investigate the properties of a sample of six BL Lacs by
fitting their spectra using our inhomogeneous jet model with an accelerating,
magnetically dominated, parabolic base, which transitions to a slowly
decelerating conical jet with a geometry based on observations of M87. Our
model is able to fit very well to the simultaneous multiwavelength spectra of
all the BL Lacs including radio observations. We find that the BL Lacs have
lower jet powers and bulk Lorentz factors than the sample of Compton-dominant
blazars investigated in Paper III, consistent with the blazar sequence.
Excitingly, we find a correlation between the radius at which the jet first
comes into equipartition and the jet power, in agreement with our prediction
from Paper II. We interpret this result as one of two physical scenarios: a
universal jet geometry which scales linearly with black hole mass or a
dichotomy in Eddington accretion rates between flat spectrum radio quasars
(FSRQs) and BL Lacs. If we assume that the jet geometry of all blazars scales
linearly with black hole mass then we find a plausible range of masses
(10^7-10^10 solar masses). We find that the quiescent gamma-ray spectrum of
Markarian 421 is best fitted by scattering of external CMB photons. We are
unable to fit the spectrum using synchrotron self-Compton emission due to
strong gamma-ray absorption via pair production even using a compact, rapidly
decelerating, jet with a very large bulk Lorentz factor (50), as has been
suggested recently. Finally, we fit to the SEDs of the four high power HSP BL
Lacs recently found by Padovani et al. 2012. We find that their high peak
frequency emission is caused by high maximum electron energies whilst the rest
of their jet properties are typical of relatively high power BL Lacs and
consistent with our predictions.


title:
Elliptic Fibrations with Rank Three Mordell-Weil Group: F-theory with
  U(1) x U(1) x U(1) Gauge Symmetry

abstract:
  We analyze general F-theory compactifications with U(1) x U(1) x U(1) Abelian
gauge symmetry by constructing the general elliptically fibered Calabi-Yau
manifolds with a rank three Mordell-Weil group of rational sections. The
general elliptic fiber is shown to be a complete intersection of two
non-generic quadrics in P^3 and resolved elliptic fibrations are obtained by
embedding the fiber as the generic Calabi-Yau complete intersection into Bl_3
P^3, the blow-up of P^3 at three points. For a fixed base B, there are finitely
many Calabi-Yau elliptic fibrations. Thus, F-theory compactifications on these
Calabi-Yau manifolds are shown to be labeled by integral points in reflexive
polytopes constructed from the nef-partition of Bl_3 P^3. We determine all 14
massless matter representations to six and four dimensions by an explicit study
of the codimension two singularities of the elliptic fibration. We obtain three
matter representations charged under all three U(1)-factors, most notably a
tri-fundamental representation. The existence of these representations, which
are not present in generic perturbative Type II compactifications, signifies an
intriguing universal structure of codimension two singularities of the elliptic
fibrations with higher rank Mordell-Weil groups. We also compute explicitly the
corresponding 14 multiplicities of massless hypermultiplets of a
six-dimensional F-theory compactification for a general base B.


title: The Effective Field Theory of Large Scale Structures at Two Loops

abstract:
  Large scale structure surveys promise to be the next leading probe of
cosmological information. It is therefore crucial to reliably predict their
observables. The Effective Field Theory of Large Scale Structures (EFTofLSS)
provides a manifestly convergent perturbation theory for the weakly non-linear
regime of dark matter, where correlation functions are computed in an expansion
of the wavenumber k of a mode over the wavenumber associated with the
non-linear scale k_nl. Since most of the information is contained at high
wavenumbers, it is necessary to compute higher order corrections to correlation
functions. After the one-loop correction to the matter power spectrum, we
estimate that the next leading one is the two-loop contribution, which we
compute here. At this order in k/k_nl, there is only one counterterm in the
EFTofLSS that must be included, though this term contributes both at tree-level
and in several one-loop diagrams. We also discuss correlation functions
involving the velocity and momentum fields. We find that the EFTofLSS
prediction at two loops matches to percent accuracy the non-linear matter power
spectrum at redshift zero up to k~0.6 h/Mpc, requiring just one unknown
coefficient that needs to be fit to observations. Given that Standard
Perturbation Theory stops converging at redshift zero at k~0.1 h/Mpc, our
results demonstrate the possibility of accessing a factor of order 200 more
dark matter quasi-linear modes than naively expected. If the remaining
observational challenges to accessing these modes can be addressed with similar
success, our results show that there is tremendous potential for large scale
structure surveys to explore the primordial universe.


title:
Reionization and Beyond: detecting the peaks of the cosmological 21cm
  signal

abstract:
  [ABRIDGED] The cosmological 21cm signal is set to become the most powerful
probe of the early Universe, with first generation interferometers aiming to
make statistical detections of reionization. There is increasing interest also
in the pre-reionization epoch when the intergalactic medium was heated by an
early X-ray background. Here we perform parameter studies varying the halo
masses hosting galaxies, and their X-ray production efficiencies. We also
relate these to popular models of Warm Dark Matter cosmologies. For each
parameter combination we compute the signal-to-noise (S/N) of the large-scale
(k~0.1/Mpc) 21cm power for both reionization and X-ray heating for a 2000h
observation with several instruments: 128 tile Murchison Wide Field Array
(MWA128T), a 256 tile extension (MWA256T), the Low Frequency Array (LOFAR), the
128 element Precision Array for Probing the Epoch of Reionization (PAPER), and
the second generation Square Kilometre Array (SKA). We show that X-ray heating
and reionization in many cases are of comparable detectability. For fiducial
astrophysical parameters, MWA128T might detect X-ray heating thanks to its
extended bandpass. When it comes to reionization, both MWA128T and PAPER will
also only achieve marginal detections, unless foregrounds on larger scales can
be mitigated. On the other hand, LOFAR should detect plausible models of
reionization at S/N > 10. The SKA will easily detect both X-ray heating and
reionization.


title:
The Orbital Ellipticity of Satellite Galaxies and the Mass of the Milky
  Way

abstract:
  We use simulations of Milky Way-sized dark matter haloes from the Aquarius
Project to investigate the orbits of substructure haloes likely, according to a
semi-analytic galaxy formation model, to host luminous satellites. These tend
to populate the most massive subhaloes and are on more radial orbits than the
majority of subhaloes found within the halo virial radius. One reason for this
(mild) kinematic bias is that many low-mass subhaloes have apocentres that
exceed the virial radius of the main host; they are thus excluded from subhalo
samples identified within the virial boundary, reducing the number of subhalos
on radial orbits. Two other factors contributing to the difference in orbital
shape between dark and luminous subhaloes are their dynamical evolution after
infall, which affects more markedly low-mass (dark) subhaloes, and a weak
dependence of ellipticity on the redshift of first infall. The ellipticity
distribution of luminous satellites exhibits little halo-to-halo scatter and it
may therefore be compared fruitfully with that of Milky Way satellites. Since
the latter depends sensitively on the total mass of the Milky Way we can use
the predicted distribution of satellite ellipticities to place constraints on
this important parameter. Using the latest estimates of position and velocity
of dwarfs compiled from the literature, we find that the most likely Milky Way
mass lies in the range $6 \times 10^{11} M_{\odot} < M_{200} < 3.1 \times
10^{12} M_{\odot}$, with a best fit value of $M_{200} = 1.1 \times 10^{12}
M_{\odot}$. This value is consistent with Milky Way mass estimates based on
dynamical tracers or the timing argument.


title: Generalized Hitchin system, Spectral curve and N=1 dynamics

abstract:
  A generalized Hitchin equation was proposed as the BPS equation for a large
class of four dimensional N=1 theories engineered using M5 branes. In this
paper, we show how to write down the spectral curve for the moduli space of
generalized Hitchin equations, and extract interesting N=1 dynamics out of it,
such as deformed modui space, chiral ring relation, SUSY breaking, etc.
Holomorphy plays a crucial role in our construction.


title:
Anisotropic dark matter distribution functions and impact on WIMP direct
  detection

abstract:
  Dark matter N-body simulations suggest that the velocity distribution of dark
matter is anisotropic. In this work we employ a mass model for the Milky Way
whose parameters are determined from a fit to kinematical data. Then we adopt
an ansatz for the dark matter phase space distribution which allows to
construct self-consistent halo models which feature a degree of anisotropy as a
function of the radius such as suggested by the simulations. The resulting
velocity distributions are then used for an analysis of current data from dark
matter direct detection experiments. We find that velocity distributions which
are radially biased at large galactocentric distances (up to the virial radius)
lead to an increased high velocity tail of the local dark matter distribution.
This affects the interpretation of data from direct detection experiments,
especially for dark matter masses around 10 GeV, since in this region the high
velocity tail is sampled. We find that the allowed regions in the dark matter
mass-cross section plane as indicated by possible hints for a dark matter
signal reported by several experiments as well as conflicting exclusion limits
from other experiments shift in a similar way when the halo model is varied.
Hence, it is not possible to improve the consistency of the data by referring
to anisotropic halo models of the type considered in this work.


title:
Characterizing SASI- and Convection-Dominated Core-Collapse Supernova
  Explosions in Two Dimensions

abstract:
  The success of the neutrino mechanism of core-collapse supernovae relies on
the supporting action of two hydrodynamic instabilities: neutrino-driven
convection and the Standing Accretion Shock Instability (SASI). Depending on
the structure of the stellar progenitor, each of these instabilities can
dominate the evolution of the gain region prior to the onset of explosion, with
implications for the ensuing asymmetries. Here we examine the flow dynamics in
the neighborhood of explosion by means of parametric two-dimensional,
time-dependent hydrodynamic simulations for which the linear stability
properties are well understood. We find that systems for which the convection
parameter is sub-critical (SASI-dominated) develop explosions once large-scale,
high-entropy bubbles are able to survive for several SASI oscillation cycles.
These long-lived structures are seeded by the SASI during shock expansions.
Finite-amplitude initial perturbations do not alter this outcome qualitatively,
though they can lead to significant differences in explosion times.
Supercritical systems (convection-dominated) also explode by developing
large-scale bubbles, though the formation of these structures is due to buoyant
activity. Non-exploding systems achieve a quasi-steady state in which the
time-averaged flow adjusts itself to be convectively sub-critical. We
characterize the turbulent flow using a spherical Fourier-Bessel decomposition,
identifying the relevant scalings and connecting temporal and spatial
components. Finally, we verify the applicability of these principles on the
general relativistic, radiation-hydrodynamic simulations of Mueller, Janka, &
Heger (2012), and discuss implications for the three-dimensional case.


title:
Two superluminous supernovae from the early universe discovered by the
  Supernova Legacy Survey

abstract:
  We present spectra and lightcurves of SNLS 06D4eu and SNLS 07D2bv, two
hydrogen-free superluminous supernovae discovered by the Supernova Legacy
Survey. At z = 1.588, SNLS 06D4eu is the highest redshift superluminous SN with
a spectrum, at M_U = -22.7 is one of the most luminous SNe ever observed, and
gives a rare glimpse into the restframe ultraviolet where these supernovae put
out their peak energy. SNLS 07D2bv does not have a host galaxy redshift, but
based on the supernova spectrum, we estimate it to be at z ~ 1.5. Both
supernovae have similar observer-frame griz lightcurves, which map to restframe
lightcurves in the U-band and UV, rising in ~ 20 restframe days or longer, and
declining over a similar timescale. The lightcurves peak in the shortest
wavelengths first, consistent with an expanding blackbody starting near 15,000
K and steadily declining in temperature. We compare the spectra to theoretical
models, and identify lines of C II, C III, Fe III, and Mg II in the spectrum of
SNLS 06D4eu and SCP 06F6, and find that they are consistent with an expanding
explosion of only a few solar masses of carbon, oxygen, and other trace metals.
Thus the progenitors appear to be related to those suspected for SNe Ic. A high
kinetic energy, 10^52 ergs, is also favored. Normal mechanisms of powering
core- collapse or thermonuclear supernovae do not seem to work for these
supernovae. We consider models powered by 56Ni decay and interaction with
circumstellar material, but find that the creation and spin-down of a magnetar
with a period of 2ms, magnetic field of 2 x 10^14 Gauss, and a 3 solar mass
progenitor provides the best fit to the data.


title: Fossilized Gravitational Wave Relic and Primordial Clocks

abstract:
  If long wavelength primordial tensor modes are coupled to short wavelength
scalar modes, the scalar curvature two-point function will have an off-diagonal
component. This `fossil' remnant is a signature of a mode coupling that cannot
be achieved in single clock inflation. Any constraint on its presence allows a
cross check of the relationship between the dynamical generation of the
fluctuations and the evolution of the inflationary background. We use the
example of non-Bunch Davies initial states for the tensor and scalar modes to
demonstrate that physically reasonable fossils, consistent with current data,
can be observable in the near future. We illustrate how the fossil off-diagonal
power spectrum is a complementary probe to the squeezed limit bispectra of the
scalar and tensor sectors individually. We also quantify the relation between
the observable signal and the squeezed limit bispectrum for a general
scalar-scalar-fossil coupling, and note the effect of superhorizon tensor modes
on the anisotropy in scalar modes.


title:
A trivial non-chaotic map lattice asymptotically indistiguishable from a
  L\'evy walk

abstract:
  In search for mathematically tractable models of anomalous diffusion, we
introduce a simple dynamical system consisting of a chain of coupled maps of
the interval whose Lyapunov exponents vanish everywhere. The volume preserving
property and the vanishing Lyapunov exponents are intended to mimic the
dynamics of polygonal billiards, which are known to give rise to anomalous
diffusion, but which are too complicated to be analyzed as thoroughly as
desired. Depending on the value taken by a single parameter \alpha, our map
experiences sub-diffusion, super-diffusion or normal diffusion. Therefore its
transport properties can be compared with those of given L\'evy walks
describing transport in quenched disordered media. Fixing \alpha\ so that the
mean square displacement generated by our map and that generated by the
corresponding L\'evy walk asymptotically coincide, we prove that all moments of
the corresponding asymptotic distributions coincide as well, hence all
observables which are expressed in terms of the moments coincide.


title:
Search for anomalous gauge couplings in semi-leptonic decays of
  $WW\gamma$ and $WZ\gamma$ in pp collisions at $\sqrt{s} =$ 8 TeV

abstract:
  A study of the Standard Model (SM) three electroweak boson production,
$WV\gamma$ where V = W or Z gauge boson, is presented concerning events with a
leptonically decaying W boson accompanied by a photon and two or more jets. We
are using the full 2012 dataset, of proton-proton collisions at a
center-of-mass energy of 8 TeV and an integrated luminosity of 19.3
fb${}^{-1}$, collected by the CMS detector at the Large Hadron Collider (LHC).
$WV\gamma$ production final states may be sensitive to anomalous
$WW\gamma\gamma$ and $WWZ\gamma$ quartic couplings. In light of the recent
discovery of a Higgs-like particle, we investigate, in a model independent way,
any deviation of gauge boson couplings with respect to the SM prediction by
setting limits on the anomalous quartic gauge couplings (aQGC) for
$WW\gamma\gamma$ and $WWZ\gamma$. Upper limits at 95% confidence level are
obtained, with and without a form factor.


title: Multi-Wavelength SEDs of Herschel Selected Galaxies in the COSMOS Field

abstract:
  We combine Herschel PACS and SPIRE maps of the full 2 deg^2 COSMOS field with
existing multi-wavelength data to obtain template and model-independent
optical-to-far-infrared spectral energy distributions (SEDs) for 4,218
Herschel-selected sources with log(L_IR/L_sun) = 9.4-13.6 and z = 0.02-3.54.
Median SEDs are created by binning the optical to far-infrared (FIR) bands
available in COSMOS as a function of infrared luminosity. Herschel probes
rest-frame wavelengths where the bulk of the infrared radiation is emitted,
allowing us to more accurately determine fundamental dust properties of our
sample of infrared luminous galaxies. We find that the SED peak wavelength
(lambda_peak) decreases and the dust mass (M_dust) increases with increasing
total infrared luminosity (L_IR). In the lowest infrared luminosity galaxies
(log(L_IR/L_sun) = 10.0-11.5), we see evidence of Polycyclic Aromatic
Hydrocarbons (PAH) features (lambda=7-9 um), while in the highest infrared
luminosity galaxies (L_IR > 10^12 L_sun) we see an increasing contribution of
hot dust and/or power-law emission, consistent with the presence of heating
from an active galactic nucleus (AGN). We study the relationship between
stellar mass and star formation rate of our sample of infrared luminous
galaxies and find no evidence that Herschel-selected galaxies follow the
SFR/M_* "main sequence" as previously determined from studies of optically
selected, star-forming galaxies. Finally, we compare the mid-infrared (MIR) to
FIR properties of our infrared luminous galaxies using the previously defined
diagnostic, IR8 = L_IR / L_8, and find that galaxies with L_IR > 10^11.3 L_sun
tend to systematically lie above (~3-5) the IR8 "infrared main sequence",
suggesting either suppressed PAH emission or an increasing contribution from
AGN heating.


title:
Helium-Abundance and Other Composition Effects on the Properties of
  Stellar Surface Convection in Solar-like Main-sequence Stars

abstract:
  We investigate the effect of helium abundance and $\alpha$-element
enhancement on the properties of convection in envelopes of solar-like
main-sequence stars stars using a grid of 3D radiation hydrodynamic
simulations. Helium abundance increases the mean molecular weight of the gas,
and alters opacity by displacing hydrogen. Since the scale of the effect of
helium may depend on the metallicity, the grid consists of simulations with
three helium abundances ($Y=0.1, 0.2, 0.3$), each with two metallicities
($Z=0.001, 0.020)$. We find that changing the helium mass fraction generally
affects structure and convective dynamics in a way opposite to that of
metallicity. Furthermore, the effect is considerably smaller than that of
metallicity. The signature of helium differs from that of metallicity in the
manner in which the photospheric velocity distribution is affected. \rev{We
also find that helium abundance and surface gravity behave largely in similar
ways, but differ in the way they affect the mean molecular weight}. A simple
model for spectral line formation suggests that the bisectors and absolute
Doppler shifts of spectral lines depends on the helium abundance. We look at
the effect of $\alpha$-element enhancement and find that it has a considerably
smaller effect on the convective dynamics in the SAL compared to that of helium
abundance.


title: SCExAO as a precursor to an ELT exoplanet direct imaging instrument

abstract:
  The Subaru Coronagraphic Extreme AO (SCExAO) instrument consists of a high
performance Phase Induced Amplitude Apodisation (PIAA) coronagraph combined
with an extreme Adaptive Optics (AO) system operating in the near-infrared (H
band). The extreme AO system driven by the 2000 element deformable mirror will
allow for Strehl ratios >90% to be achieved in the H-band when it goes closed
loop. This makes the SCExAO instrument a powerful platform for high contrast
imaging down to angular separations of the order of 1lambda/D and an ideal
testbed for exploring coronagraphic techniques for ELTs. In this paper we
report on the recent progress in regards to the development of the instrument,
which includes the addition of a visible bench that makes use of the light at
shorter wavelengths not currently utilized by SCExAO and closing the loop on
the tip/tilt wavefront sensor. We will also discuss several exciting guest
instruments which will expand the capabilities of SCExAO over the next few
years; namely CHARIS which is a integral field spectrograph as well as
VAMPIRES, a visible aperture masking experiment based on polarimetric analysis
of circumstellar disks. In addition we will elucidate the unique role extreme
AO systems will play in enabling high precision radial velocity spectroscopy
for the detection of small companions.


title:
MAMA: An Algebraic Map for the Secular Dynamics of Planetesimals in
  Tight Binary Systems

abstract:
  We present an algebraic map (MAMA) for the dynamical and collisional
evolution of a planetesimal swarm orbiting the main star of a tight binary
system (TBS). The orbital evolution of each planetesimal is dictated by the
secular perturbations of the secondary star and gas drag due to interactions
with a protoplanetary disk. The gas disk is assumed eccentric with a constant
precession rate. Gravitational interactions between the planetesimals are
ignored. All bodies are assumed coplanar. A comparison with full N-body
simulations shows that the map is of the order of 100 times faster, while
preserving all the main characteristics of the full system.
  In a second part of the work, we apply MAMA to the \gamma-Cephei, searching
for friendly scenarios that may explain the formation of the giant planet
detected in this system. For low-mass protoplanetary disks, we find that a
low-eccentricity static disk aligned with the binary yields impact velocities
between planetesimals below the disruption threshold. All other scenarios
appear hostile to planetary formation.


title: Higher Order Spin Noise Statistics

abstract:
  The optical spin noise spectroscopy (SNS) is a minimally invasive route
towards obtaining dynamical information about electrons and atomic gases by
measuring mesoscopic time-dependent spin fluctuations. Recent improvements of
the sensitivity of SNS should make it possible to observe higher order spin
correlators at thermodynamic equilibrium. We develop theoretical methods to
explore higher order (3rd and 4th) cumulants of the spin noise in the frequency
domain. We make predictions for the possible functional form of these
correlators in single quantum dot experiments and then apply the method of the
stochastic path integral to estimate effects of many-body interactions.


title:
Nonlinear Observer Design and Synchronization Analysis for Classical
  Models of Neural Oscillators

abstract:
  This work explores four nonlinear classical models of neural oscillators, the
Hodgkin-Huxley model, the Fitzhugh-Nagumo model, the Morris-Lecar model, and
the Hindmarsh-Rose model. Nonlinear contraction theory is used to develop
observers and perform synchronization analysis on these systems. Neural
oscillation and signaling models are based on the biological function of the
neuron, with behavior mediated through the channeling of ions across the cell
membrane. The variable assumed to be measured is the membrane potential, which
may be obtained empirically through the use of a neuronal force-clamp system,
or may be transmitted through the axon to other neurons. All other variables
are estimated by using partial state or full state observers. Basic observer
rate convergence analysis is performed for the Fitzhugh Nagumo system, partial
state observer design is performed for the Morris-Lecar system, and basic
synchronization analysis is performed for both the Fitzhugh-Nagumo and the
Hodgkin-Huxley systems.


title: Some properties of regular integers modulo n

abstract:
  Denoting by V(n) the number of regular integers $(\text{mod}n)$, we study
properties of the sequences $\displaystyle
\biggl(\frac{V(n+1)}{V(n)}\biggr)_{n\geq1}$ and $\displaystyle
(V(n+1)-V(n))_{n\geq1}$. We also prove that the sets $\displaystyle\biggl
\lbrace\frac{\psi(n)}{V(n)} : n\geq1\biggr \rbrace$ and $\displaystyle\biggl
\lbrace\frac{V(n)}{\phi(n)} : n\geq1\biggr \rbrace$ are everywhere dense in
$(1,+\infty)$.


title: Tiling in bipartite graphs with asymmetric minimum degrees

abstract:
  The problem of determining the optimal minimum degree condition for a
balanced bipartite graph on 2ms vertices to contain m vertex disjoint copies of
K_{s,s} was solved by Zhao. Later Hladk\'y and Schacht, and Czygrinow and
DeBiasio determined the optimal minimum degree condition for a balanced
bipartite graph on 2m(s+t) vertices to contain m vertex disjoint copies of
K_{s,t} for fixed positive integers s<t.
  For a balanced bipartite graph G[U,V], let \delta_U be the minimum degree
over all vertices in U and \delta_V be the minimum degree over all vertices in
V. We consider the problem of determining the optimal value of
\delta_U+\delta_V which guarantees that G can be tiled with K_{s,s}. We show
that the optimal value depends on D:=|\delta_V-\delta_U|. When D is small, we
show that \delta_U+\delta_V\geq n+3s-5 is best possible. As D becomes larger,
we show that \delta_U+\delta_V can be made smaller, but no smaller than
n+2s-2s^{1/2}. However, when D=n-C for some constant C, we show that there
exist graphs with \delta_U+\delta_V\geq n+s^{s^{1/3}} which cannot be tiled
with K_{s,s}.


title:
Analysis of a superbolide from a Damocloid observed over Spain on July
  13, 2012

abstract:
  A superbolide with an estimated absolute magnitude of -20+-1 was seen on July
13, 2012 over the center and south of Spain. This extraordinary event, which
was witnessed by numerous casual observers, was recorded in the framework of
the continuous fireball monitoring and meteor spectroscopy campaign performed
by the SPanish Meteor Network (SPMN). Thus, because of optimal weather
conditions, the bolide was imaged from ten meteor observing stations. Here we
present the analysis of this magnificent event, which is the brightest fireball
ever recorded by our team. The atmospheric trajectory of the bolide and the
orbit in the Solar System of the parent meteoroid were obtained. The emission
spectrum produced during the ablation of this particle is also discussed. We
found that the meteoroid, which was following a Halley Type Comet orbit, was
depleted in Na and had a tensile strength one order of magnitude higher than
that corresponding to typical cometary materials. By means of orbital analysis
tools we have investigated the likely parent body of this particle and the
results suggest that the progenitor is a damocloid. The impact area of the
hypothetical remnants of the meteoroid is also given and a search for
meteorites was performed, but none were found.


title: Continental Diversity of Chenopodium album Seedling Recruitment

abstract:
  Chenopodium album seedling emergence studies were conducted at nine European
and two North American locations comparing local populations with a common
population from Denmark. It is hypothesized that C. album seedling recruitment
timing and magnitude have adapted to environmental and cropping system
practices of a locality. Limitations in the habitat (filter 1) were reflected
in local C. album population recruitment season length. Generally, the duration
of seedling recruitment of both populations (local; DEN-COM) increased with
decreasing latitude, north-to-south. In general, compared to the local
population, DEN-COM recruitment at locations north of Denmark was longer and
south of Denmark was shorter, and ended sooner. Generally, the local cropping
system disturbances (CSD) period increased with decreasing latitude. The total
duration of the CSD period was over twice as long in the south as that in the
north. Recruitment at each locality possessed seasonal structure (time, number)
consisting of 2-4 discrete seasonal cohorts. This may be an adaptive means by
which C. album searches for, and exploits, recruitment opportunity just prior
to, and after, predictable disturbances. The control of C. album seedling
emergence is contained in the heteroblastic traits of its locally adapted
seeds, and is stimulated by a complex interaction of light, heat, water,
nitrate and oxygen signals inherent in the local environment. Our observations
of complex recruitment patterns occurring at critical cropping times is strong
evidence that C. album possesses a flexible and sensitive germination
regulation system adaptable to opportunity in many different Eurasian and North
American agricultural habitats.


title: Viscous control of peeling an elastic sheet by bending and pulling

abstract:
  Propagation of a viscous fluid beneath an elastic sheet is controlled by
local dynamics at the peeling front, in close analogy with the capillary-driven
spreading of drops over a precursor film. Here we identify propagation laws for
a generic elastic peeling problem in the distinct limits of peeling by bending
and peeling by pulling, and apply our results to the radial spread of a fluid
blister over a thin pre-wetting film. For the case of small deformations
relative to the sheet thickness, peeling is driven by bending, leading to
radial growth as $t^{7/22}$. Experimental results reproduce both the spreading
behaviour and the bending wave at the front. For large deformations relative to
the sheet thickness, stretching of the blister cap and the consequent tension
can drive peeling either by bending or by pulling at the front, both leading to
radial growth as $t^{3/8}$. In this regime, detailed predictions give excellent
agreement and explanation of previous experimental measurements of spread in
the pulling regime in an elastic Hele-Shaw cell \cite{puzovic-2012}.


title:
Evidence for Radiogenic Sulfur-32 in Type AB Presolar Silicon Carbide
  Grains?

abstract:
  We report C, Si, and S isotope measurements on 34 presolar silicon carbide
grains of Type AB, characterized by 12C/13C < 10. Nitrogen, Mg-Al-, and
Ca-Ti-isotopic compositions were measured on a subset of these grains. Three
grains show large 32S excesses, a signature that has been previously observed
for grains from supernovae (SNe). Enrichments in 32S may be due to
contributions from the Si/S zone and the result of S molecule chemistry in
still unmixed SN ejecta or due to incorporation of radioactive 32Si from C-rich
explosive He shell ejecta. However, a SN origin remains unlikely for the three
AB grains considered here, because of missing evidence for 44Ti, relatively low
26Al/27Al ratios (a few times 10-3), and radiogenic 32S along with low 12C/13C
ratios. Instead, we show that born-again asymptotic giant branch (AGB) stars
that have undergone a very-late thermal pulse (VLTP), known to have low 12C/13C
ratios and enhanced abundances of the light s-process elements, can produce
32Si, which makes such stars attractive sources for AB grains with 32S
excesses. This lends support to the proposal that at least some AB grains
originate from born-again AGB stars, although uncertainties in the born-again
AGB star models and possible variations of initial S-isotopic compositions in
the parent stars of AB grains make it difficult to draw a definitive
conclusion.


title:
A Search for $t\bar{t}$ Resonances in Lepton Plus Jets Events with ATLAS
  using 14 fb$^{-1}$ of Proton-Proton Collisions at $\sqrt{s}$ = 8 TeV

abstract:
  Some Beyond the Standard Model theories predict new particles that decay
predominantly into top-antitop quark pairs. A search for top-antitop quark
resonances that decay into the lepton plus jets final state is carried out with
the ATLAS experiment at the LHC using 14 fb$^{-1}$ of $\sqrt{s}$ = 8 TeV
proton-proton collisions. The search considers both cases where all of the
final state jets are isolated and where some or all of the top quark decay
products are merged into a single jet. Mass exclusion limits at a 95%
credibility level are set for two benchmark models, one predicting leptophobic
topcolor Z' bosons and the other predicting Randall-Sundrum Kaluza-Klein
gluons.


title:
Constraints on decreases in Eta Carinae's mass loss from 3D hydrodynamic
  simulations of its binary colliding winds

abstract:
  Recent work suggests that the mass-loss rate of the primary star (Eta A) in
the massive colliding wind binary Eta Carinae dropped by a factor of 2-3
between 1999 and 2010. We present results from large- (r=1545au) and small-
(r=155au) domain, 3D smoothed particle hydrodynamic (SPH) simulations of Eta
Car's colliding winds for 3 Eta A mass-loss rates (2.4, 4.8, and 8.5 x 10^-4
M_sun/yr), investigating the effects on the dynamics of the binary wind-wind
collision (WWC). These simulations include orbital motion, optically thin
radiative cooling, and radiative forces. We find that Eta A's mass-loss rate
greatly affects the time-dependent hydrodynamics at all spatial scales
investigated. The simulations also show that the post-shock wind of the
companion star (Eta B) switches from the adiabatic to the radiative-cooling
regime during periastron passage. The SPH simulations together with 1D
radiative transfer models of Eta A's spectra reveal that a factor of 2 or more
drop in Eta A's mass-loss rate should lead to substantial changes in numerous
multiwavelength observables. Recent observations are not fully consistent with
the model predictions, indicating that any drop in Eta A's mass-loss rate was
likely by a factor < 2 and occurred after 2004. We speculate that most of the
recent observed changes in Eta Car are due to a small increase in the WWC
opening angle that produces significant effects because our line-of-sight to
the system lies close to the dense walls of the WWC zone. A modest decrease in
Eta A's mass-loss rate may be responsible, but changes in the wind/stellar
parameters of Eta B cannot yet be fully ruled out. We suggest observations
during Eta Car's next periastron in 2014 to further test for decreases in Eta
A's mass-loss rate. If Eta A's mass-loss rate is declining and continues to do
so, the 2014 X-ray minimum should be even shorter than that of 2009.


title:
Evidence for nuclear radio jet and its structure down to <100
  Schwarzschild radii in the center of the Sombrero galaxy (M 104, NGC 4594)

abstract:
  Abridged: We investigated the detailed radio structure of the nucleus of the
Sombrero galaxy using high-resolution, quasi-simultaneous, multi-frequency,
phase-referencing VLBA observations. We obtained the VLBI images toward this
nucleus, with unprecedented sensitivities and resolutions, at the seven
frequencies between 1.4 and 43 GHz, where those at 15, 24 and 43 GHz are the
first clear VLBI detections. At 43 GHz, the nuclear structure was imaged on a
linear scale under 100 Schwarzschild radii. For the first time, we have
discovered the presence of the extended structure in this nucleus, which is
directing from the radio core in two sides toward northwest/southeast
directions. The nuclear structure shows a clear spatial gradient on the radio
spectra, which is similar to that commonly seen in more luminous AGN with
powerful relativistic jets. Moreover, the radio core shows a
frequency-dependent size with an elongated shape, and the position of the core
also tends to be frequency dependent. A set of these new findings provide
evidence that the central engine of the Sombrero is powering radio jets. Based
on the observed brightness ratio of jet-to-counter jet, core position shift and
its comparison with a theoretical model, we constrained the following
fundamental physical parameters for the M 104 jets: (1) the northern side is
the approaching jet, whereas the southern side is receding: (2) the inclination
angle of the jet is relatively close to our line-of-sight, probably less than
~25degrees: (3) the jet intrinsic velocity is highly sub-relativistic at a
speed less than ~0.2c. The derived pole-on nature of the M 104 jet is in
accordance with the previous argument that M 104 contains a true type II AGN,
i.e., the broad line region of this nucleus is actually absent or intrinsically
weak, if the plane of the presumed circumnuclear torus is perpendicular to the
axis of the radio jets.


title: Cycle density in infinite Ramanujan graphs

abstract:
  We introduce a technique using nonbacktracking random walk for estimating the
spectral radius of simple random walk. This technique relates the density of
nontrivial cycles in simple random walk to that in nonbacktracking random walk.
We apply this to infinite Ramanujan graphs, which are regular graphs whose
spectral radius equals that of the tree of the same degree. Kesten showed that
the only infinite Ramanujan graphs that are Cayley graphs are trees. This
result was extended to unimodular random rooted regular graphs by Ab\'{e}rt,
Glasner and Vir\'{a}g. We show that an analogous result holds for all regular
graphs: the frequency of times spent by simple random walk in a nontrivial
cycle is a.s. 0 on every infinite Ramanujan graph. We also give quantitative
versions of that result, which we apply to answer another question of
Ab\'{e}rt, Glasner and Vir\'{a}g, showing that on an infinite Ramanujan graph,
the probability that simple random walk encounters a short cycle tends to 0
a.s. as the time tends to infinity.


title: Semiclassical theory of speckle correlations

abstract:
  Coherent wave propagation in random media results in a characteristic speckle
pattern, with spatial intensity correlations with short-range and long-range
behavior. Here, we show how the speckle correlation function can be obtained
from a ray picture for two representative geometries: A chaotic cavity and a
random waveguide. Our calculation allows us to study the crossover between a
"ray limit" and a "wave limit", in which the Ehrenfest time $\tau_E$ is larger
or smaller than the typical transmission time $\tau_D$, respectively.
Remarkably, long-range speckle correlations persist in the ray limit $\tau_E
\gg \tau_D$.


title: Decentralized Signal Control for Urban Road Networks

abstract:
  We propose in this paper a decentralized traffic signal control policy for
urban road networks. Our policy is an adaptation of a so-called BackPressure
scheme which has been widely recognized in data network as an optimal
throughput control policy. We have formally proved that our proposed
BackPressure scheme, with fixed cycle time and cyclic phases, stabilizes the
network for any feasible traffic demands. Simulation has been conducted to
compare our BackPressure policy against other existing distributed control
policies in various traffic and network scenarios. Numerical results suggest
that the proposed policy can surpass other policies both in terms of network
throughput and congestion.


title:
Binary Black Hole Accretion From a Circumbinary Disk: Gas Dynamics
  Inside the Central Cavity

abstract:
  We present the results of 2D hydrodynamical simulations of circumbinary disk
accretion using the finite-volume code DISCO. This code solves the 2D viscous
Navier-Stokes equations on a high-resolution moving mesh which shears with the
fluid flow, greatly reducing advection errors in comparison with a fixed grid.
We perform a series of simulations for binary mass ratios in the range 0.026 <
q < 1.0, each lasting longer than a viscous time so that we reach a
quasi-steady accretion state. In each case, we find that gas is efficiently
stripped from the inner edge of the circumbinary disk and enters the cavity
along accretion streams, which feed persistent "mini-disks" surrounding each
black hole. We find that for q > 0.1, the binary excites eccentricity in the
inner region of the circumbinary disk, creating an overdense lump which gives
rise to enhanced periodicity in the accretion rate. The dependence of the
periodicity on mass ratio may provide a method for observationally inferring
mass ratios from measurements of the accretion rate. We also find that for all
mass ratios studied, the magnitude of the accretion onto the secondary is
sufficient to drive the binary toward larger mass ratio. This suggests a
mechanism for biasing mass ratio distributions toward equal mass.


title: Abstract commensurability and the Gupta--Sidki group

abstract:
  We study the subgroup structure of the infinite torsion $p$-groups defined by
Gupta and Sidki in 1983. In particular, following results of Grigorchuk and
Wilson for the first Grigorchuk group, we show that all infinite finitely
generated subgroups of the Gupta--Sidki 3-group $G$ are abstractly
commensurable with $G$ or $G\times G$. As a consequence, we show that $G$ is
subgroup separable and from this it follows that its membership problem is
soluble. Along the way, we obtain a characterization of finite subgroups of $G$
and establish an analogue for the Grigorchuk group.


title: Fluctuating hydrodynamics of multi-species, non-reactive mixtures

abstract:
  In this paper we discuss the formulation of the fuctuating Navier-Stokes
(FNS) equations for multi-species, non-reactive fluids. In particular, we
establish a form suitable for numerical solution of the resulting stochastic
partial differential equations. An accurate and efficient numerical scheme,
based on our previous methods for single species and binary mixtures, is
presented and tested at equilibrium as well as for a variety of non-equilibrium
problems. These include the study of giant nonequilibrium concentration
fluctuations in a ternary mixture in the presence of a diffusion barrier, the
triggering of a Rayleigh-Taylor instability by diffusion in a four-species
mixture, as well as reverse diffusion in a ternary mixture. Good agreement with
theory and experiment demonstrates that the formulation is robust and can serve
as a useful tool in the study of thermal fluctuations for multi-species fluids.
The extension to include chemical reactions will be treated in a sequel paper.


title: Bottom-up Graphene Nanoribbon Field-Effect Transistors

abstract:
  Recently developed processes have enabled bottom-up chemical synthesis of
graphene nanoribbons (GNRs) with precise atomic structure. These GNRs are ideal
candidates for electronic devices because of their uniformity, extremely narrow
width below 1 nm, atomically perfect edge structure, and desirable electronic
properties. Here, we demonstrate nanoscale chemically synthesized GNR
field-effect transistors, made possible by development of a new layer transfer
process. We observe strong environmental sensitivity and unique transport
behavior characteristic of sub-1nm width GNRs.


title: Shadowing near nonhyperbolic fixed points

abstract:
  We use Lyapunov type functions to find conditions of finite shadowing in a
neighborhood of a nonhyperbolic fixed point of a one-dimensional or
two-dimensional homeomorphism or diffeomorphism. A new concept of shadowing in
which we control the size of one-step errors is introduced in the case of a
nonisolated fixed point.


title: Potentially Singular Solutions of the 3D Incompressible Euler Equations

abstract:
  Whether the 3D incompressible Euler equations can develop a singularity in
finite time from smooth initial data is one of the most challenging problems in
mathematical fluid dynamics. This work attempts to provide an affirmative
answer to this long-standing open question from a numerical point of view, by
presenting a class of potentially singular solutions to the Euler equations
computed in axisymmetric geometries. The solutions satisfy a periodic boundary
condition along the axial direction and no-flow boundary condition on the solid
wall. The equations are discretized in space using a hybrid 6th-order Galerkin
and 6th-order finite difference method, on specially designed adaptive (moving)
meshes that are dynamically adjusted to the evolving solutions. With a maximum
effective resolution of over $(3 \times 10^{12})^{2}$ near the point of the
singularity, we are able to advance the solution up to $\tau_{2} = 0.003505$
and predict a singularity time of $t_{s} \approx 0.0035056$, while achieving a
\emph{pointwise} relative error of $O(10^{-4})$ in the vorticity vector
$\omega$ and observing a $(3 \times 10^{8})$-fold increase in the maximum
vorticity $\|\omega\|_{\infty}$. The numerical data are checked against all
major blowup (non-blowup) criteria, including Beale-Kato-Majda,
Constantin-Fefferman-Majda, and Deng-Hou-Yu, to confirm the validity of the
singularity. A local analysis near the point of the singularity also suggests
the existence of a self-similar blowup in the meridian plane.


title:
Gains from switching and evolutionary stability in multi-player matrix
  games

abstract:
  In this paper we unify, simplify, and extend previous work on the
evolutionary dynamics of symmetric $N$-player matrix games with two pure
strategies. In such games, gains from switching strategies depend, in general,
on how many other individuals in the group play a given strategy. As a
consequence, the gain function determining the gradient of selection can be a
polynomial of degree $N-1$. In order to deal with the intricacy of the
resulting evolutionary dynamics, we make use of the theory of polynomials in
Bernstein form. This theory implies a tight link between the sign pattern of
the gains from switching on the one hand and the number and stability
properties of the rest points of the replicator dynamics on the other hand.
While this relationship is a general one, it is most informative if gains from
switching have at most two sign changes, as it is the case for most
multi-player matrix games considered in the literature. We demonstrate that
previous results for public goods games are easily recovered and extended using
this observation. Further examples illustrate how focusing on the sign pattern
of the gains from switching obviates the need for a more involved analysis.