title: Cosmology in General Massive Gravity Theories

abstract:
  We study the cosmology of general massive gravity theories with five
propagating degrees of freedom. This large class of theories includes both the
case with a residual Lorentz invariance as the cases with simpler rotational
invariance. We find that the existence of a nontrivial homogeneous FRW
background, in addition to selecting the lorentz-breaking case, implies in
general that perturbations around strict Minkowski or dS space are strongly
coupled. The result is that dark energy can be naturally accounted for in
massive gravity but its equation of state w_eff has to deviate from -1. We find
indeed a relation between the strong coupling scale of perturbations and the
deviation of w_eff from -1. Taking into account current limits on w_eff and
submillimiter tests of the Newton's law as a limit on the possible strong
coupling regime, we find that it is still possible to have a weakly coupled
theory in a quasi dS background. Future experimental improvements may be used
to predict w_eff in a weakly coupled massive gravity theory


title:
Electron Cloud Observations and Predictions at KEKB, PEP-II and SuperB
  Factories

abstract:
  Electron cloud observations at B factories, i.e. KEKB and PEP-II, are
reviewed. Predictions of electron cloud effects at Super B factories, i.e.
SuperB and Super KEKB, are also reviewed.


title:
Fractional variational problems depending on fractional derivatives of
  differentiable functions with application to nonlinear chaotic systems

abstract:
  In the present work, we formulate a necessary condition for functionals with
Lagrangians depending on fractional derivatives of differentiable functions to
possess an extremum. The Euler-Lagrange equation we obtained generalizes
previously known results in the literature and enables us to construct simple
Lagrangians for nonlinear systems. As examples of application, we obtain
Lagrangians for some chaotic dynamical systems.


title:
A Hamilton-Jacobi approach for a model of population structured by space
  and trait

abstract:
  We study a non-local parabolic Lotka-Volterra type equation describing a
population structured by a space variable x 2 Rd and a phenotypical trait 2 .
Considering diffusion, mutations and space-local competition between the
individuals, we analyze the asymptotic (long- time/long-range in the x
variable) exponential behavior of the solutions. Using some kind of real phase
WKB ansatz, we prove that the propagation of the population in space can be
described by a Hamilton-Jacobi equation with obstacle which is independent of .
The effective Hamiltonian is derived from an eigenvalue problem. The main
difficulties are the lack of regularity estimates in the space variable, and
the lack of comparison principle due to the non-local term.


title:
Borel Isomorphic Dimensionality Reduction of Data and Supervised
  Learning

abstract:
  In this project we further investigate the idea of reducing the
dimensionality of datasets using a Borel isomorphism with the purpose of
subsequently applying supervised learning algorithms, as originally suggested
by my supervisor V. Pestov (in 2011 Dagstuhl preprint). Any consistent learning
algorithm, for example kNN, retains universal consistency after a Borel
isomorphism is applied. A series of concrete examples of Borel isomorphisms
that reduce the number of dimensions in a dataset is provided, based on
multiplying the data by orthogonal matrices before the dimensionality reducing
Borel isomorphism is applied. We test the accuracy of the resulting classifier
in a lower dimensional space with various data sets. Working with a phoneme
voice recognition dataset, of dimension 256 with 5 classes (phonemes), we show
that a Borel isomorphic reduction to dimension 16 leads to a minimal drop in
accuracy. In conclusion, we discuss further prospects of the method.


title:
Metals in the Intracluster Medium of MS 1512.4+3647 Observed with
  Suzaku: Implications for the Metal Enrichment History

abstract:
  The cluster of galaxies MS 1512.4+3647 (z=0.372) was observed with Suzaku for
270 ks. Besides the Fe abundance, the abundances of Mg, Si, S, and Ni are
separately determined for the first time in a medium redshift cluster (z>0.3).
The derived abundance pattern of MS 1512.4+3647 is consistent with those of
nearby clusters, suggesting that the system has similar contributions from
supernovae (SNe) Ia and SNe II to nearby clusters. The number ratio of SNe II
to SNe Ia is $\sim3$. The estimated total numbers of both SNe II and SNe Ia
against gas mass indicate similar correlation with those for the nearby
clusters. The abundance results of MS 1512.4+3647 is consistent with the
standard scenario that the SN II rate history roughly follows the
star-formation history which has a peak at 1<z<2 and then declines by about one
order of magnitude toward $z\sim0$. The similar number of SNe Ia to the nearby
clusters suggests that the SN Ia rate declines steeply from z=0.37 to z=0
and/or SN Ia explosions occurred predominantly at larger redshifts.


title:
AIDSS-HR: An Automated Intelligent Decision Support System for Enhancing
  the Performance of Employees

abstract:
  The performance of employees in an organization is a very important issue for
effective delivery and output. Various performance management systems with the
aid of Information and Communication Technology (ICT) are currently being used
by companies. Such systems are most of the time connected and accessible
through to the internet / www. Through review of relevant literature and a
system development methodology, this paper proposes an Automated Intelligent
Decision Support Human Resource (AIDSS-HR) system that seeks to control and
manage employee activities by tracking the number of years a staff has been at
post, keeping inventory on logistics, analyzing appraisal reports of an
individual staff and invoking real time prompts devoid of false alarm. The
implementation of AIDSS-HR will improve the performance management of employees
and benefit the organization, employees and developing nations as a whole.


title:
Heat dissipation and its relation to thermopower in single-molecule
  junctions

abstract:
  Motivated by recent experiments [Lee et al. Nature 498, 209 (2013)], we
present here a detailed theoretical analysis of the Joule heating in
current-carrying single-molecule junctions. By combining the Landauer approach
for quantum transport with ab initio calculations, we show how the heating in
the electrodes of a molecular junction is determined by its electronic
structure. In particular, we show that in general the heat is not equally
dissipated in both electrodes of the junction and it depends on the bias
polarity (or equivalently on the current direction). These heating asymmetries
are intimately related to the thermopower of the junction as both these
quantities are governed by very similar principles. We illustrate these ideas
by analyzing single-molecule junctions based on benzene derivatives with
different anchoring groups. The close relation between heat dissipation and
thermopower provides general strategies for exploring fundamental phenomena
such as the Peltier effect or the impact of quantum interference effects on the
Joule heating of molecular transport junctions.


title:
Phase diagram of the spin-1 Heisenberg model with three-site
  interactions on the square lattice

abstract:
  We study the spin S=1 antiferromagnetic Heisenberg model on the square
lattice with, in addition to the nearest-neighbor interaction, a three-site
interaction of the form (S_i S_j)*(S_j S_k) + h.c.. This interaction appears
naturally in a strong coupling exansion of the two-orbital, half-filled Hubbard
model. For spin 1/2, this model reduces to a Heisenberg model with bilinear
interactions up to third neighbors, with a second-neighbor interaction twice as
large the third-neighbor one, a very frustrated model with an infinite family
of helical classical ground states in a large parameter range. Using a variety
of analytical and numerical methods, we show that the spin-1 case is also very
frustrated, and that its phase diagram is even richer, with possibly the
succession of seven different phases as a function of the ratio of the
three-site interaction to the bilinear one. The phases are either purely
magnetic phases with collinear order, or of mixed magnetic and quadrupolar
character with helical order.


title:
Demonstrating the feasibility of probing the neutron star equation of
  state with second-generation gravitational wave detectors

abstract:
  Fisher matrix and related studies have suggested that with second-generation
gravitational wave detectors, it may be possible to infer the equation of state
of neutron stars using tidal effects in binary inspiral. Here we present the
first fully Bayesian investigation of this problem. We simulate a realistic
data analysis setting by performing a series of numerical experiments of binary
neutron star signals hidden in detector noise, assuming the projected final
design sensitivity of the Advanced LIGO- Virgo network. With an astrophysical
distribution of events (in particular, uniform in co-moving volume), we find
that only a few tens of detections will be required to arrive at strong
constraints, even for some of the softest equations of state in the literature.
Thus, direct gravitational wave detection will provide a unique probe of
neutron star structure.


title: Multiscale principal component analysis

abstract:
  Principal component analysis (PCA) is an important tool in exploring data.
The conventional approach to PCA leads to a solution which favours the
structures with large variances. This is sensitive to outliers and could
obfuscate interesting underlying structures. One of the equivalent definitions
of PCA is that it seeks the subspaces that maximize the sum of squared pairwise
distances between data projections. This definition opens up more flexibility
in the analysis of principal components which is useful in enhancing PCA. In
this paper we introduce scales into PCA by maximizing only the sum of pairwise
distances between projections for pairs of datapoints with distances within a
chosen interval of values [l,u]. The resulting principal component
decompositions in Multiscale PCA depend on point (l,u) on the plane and for
each point we define projectors onto principal components. Cluster analysis of
these projectors reveals the structures in the data at various scales. Each
structure is described by the eigenvectors at the medoid point of the cluster
which represent the structure. We also use the distortion of projections as a
criterion for choosing an appropriate scale especially for data with outliers.
This method was tested on both artificial distribution of data and real data.
For data with multiscale structures, the method was able to reveal the
different structures of the data and also to reduce the effect of outliers in
the principal component analysis.


title: Inflection points and asymptotic lines on Lagrangean surfaces

abstract:
  We describe the structure of the asymptotic lines near an inflection point of
a Lagrangean surface, proving that in the generic situation it corresponds to
two of the three possible cases when the discriminant curve has a cusp
singularity. Besides being stable in general, inflection points are proved to
exist on a compact Lagrangean surface whenever its Euler characteristic does
not vanish.


title: Unbounded convex polygons as polynomial images of the plane

abstract:
  In this note we show that unbounded convex polygons with nonparallel
unbounded edges are polynomial images of ${\mathbb R}^2$, whereas their
interiors are polynomial images of ${\mathbb R}^3$


title:
Electromagnetic self-force on a static charge in Schwarzschild-de Sitter
  spacetimes

abstract:
  We compute the self-force acting on an electric charge at rest in
Schwarzschild-de Sitter spacetimes, allowing the cosmological constant to be
either positive or negative. In the case of a positive cosmological constant,
we show that the self-force is always positive, representing a repulsion from
the black hole, and monotonically decreasing with increasing distance from the
black hole. The spectrum of results is richer in the case of a negative
cosmological constant. Here the self-force is not always positive --- it is
negative when the black-hole and cosmological scales are comparable and the
charge is close to the black hole --- and not always monotonically decreasing
--- it is actually monotonically increasing when the cosmological scale is
sufficiently small compared to the black-hole scale. The self-force also
approaches a constant asymptotic value when the charge is moved to large
cosmological distances; this feature can be explained in terms of an
interaction between the charge and the conformal boundary at infinity, which
acts as a grounded conductor.


title: Local rigidity for PGL(3,C)-representations of 3-manifold groups

abstract:
  Let M be a non-compact hyperbolic 3-manifold that has a triangulation by
positively oriented ideal tetraedra. We explain how to produce local
coordinates for the variety defined by the gluing equations for
PGL(3,C)-representations. In particular we prove local rigidity of the
"geometric" representation in PGL(3,C), recovering a recent result of
Menal-Ferrer and Porti. More generally we give a criterion for local rigidty of
PGL(3,C)-representations and provide detailed analysis of the figure eight knot
sister manifold exhibiting the different possibilities that can occur.


title:
Unprecedented temporal evolution of the broad-band emission of the BL
  Lac Mrk 501

abstract:
  The TeV BL Lac object Markarian 501 has been the subject of a 4.5 month
multi-instrument campaign conducted in 2009, which provided an excellent
temporal and energy coverage from radio to very high energy gamma rays (>100
GeV, VHE). During the campaign, Mrk 501 was mostly in a comparably low state,
but for two flares at VHE with very different characteristics. While the second
flare seems to be correlated with a moderate increase in the X-ray flux, the
first one is most likely accompanied by a shift of the synchrotron bump towards
higher energies. Moreover, the first flare occurs during an abrupt change in
the polarized optical flux, and was preceded by a rotation of the electric
field vector position angle. This is the first time that such behavior is
observed in a high-frequency-peaked BL Lac object, while similar events have
been seen in the low-frequency peaked BL Lac object BL Lacertae and the flat
spectrum radio quasar PKS 1510-089, hence suggesting that similar physical
processes occur in the jets of different blazar subclasses.


title: A search for lines in the bright X-ray afterglow of GRB120711A

abstract:
  GRB120711A, discovered and rapidly localized by the INTEGRAL satellite,
attracted particular interest due to its high gamma-ray fluence, very bright
X-ray afterglow, and the detection of a prompt optical transient and of
long-lasting emission at GeV energies. A follow-up observation carried out with
the XMM-Newton satellite has provided an X-ray spectrum in the 0.3-10 keV with
unprecedented statistics for a GRB afterglow 20 hours after the burst. The
spectrum is well fit by a power-law with photon index 1.87+-0.01, modified by
absorption in our Galaxy and in the GRB host at z=1.4. A Galactic absorption
consistent with that estimated from neutral hydrogen observations is obtained
only with host metallicity lower than 0.05 of the Solar value. We report the
results of a sensitive search for emission and absorption lines using the
matched filter smoothing method (Rutledge and Sako 2003). No statistically
significant lines were found. The upper limits on the equivalent width of
emission lines, derived through Monte Carlo simulations, are few tens of eV, a
factor about 10 lower than that of the possible lines reported in the
literature for other bursts.


title: Charged Lepton Flavor Violation Experiments

abstract:
  The experimental status of charged lepton flavor violation searches is
briefly reviewed, with particular emphasis on the three classical searches
involving muon transisions: $\mu \to e \gamma$, $\mu \to e$ conversion and $\mu
\to 3e$.


title: Bouligand-Severi $k$-tangents and strongly semisimple MV-algebras

abstract:
  An algebra $A$ is said to be strongly semisimple if every principal
congruence of $A$ is an intersection of maximal congruences. We give a
geometrical characterisation of strongly semisimple MV-algebras in terms of
Bouligand-Severi $k$-tangents. The latter are a $k$-dimensional generalisation
of the classical Bouligand-Severi tangents.


title:
Holographic superconductors with Weyl Corrections via gauge/gravity
  duality

abstract:
  In this paper, we analytically compute the basic parameters of the p-wave
holographic superconductors with Weyl geometrical corrections using the
matching method. The explicit correspondence between the critical temperature
$T_c$ and the dual charge density $\rho$ has been calculated as
$T_c\propto\rho^{{1}{3}}$ and the dependence of the vacuum expectation value
for the dual condensate operator $\cal{O}$ on the temperature has been found
analytically in the form $<{\cal O}_{+}>\propto
T_c^{{3}{2}}T^{\Delta-{1}{2}}\sqrt{1-({T}{T_c})^3}$. The critical exponent
${1}{2}$ is an universal quantity according to predictions of the mean field
theory and independent from the Weyl coupling $\gamma$. Our analytical results
confirm the numerical results and also agree on computations using by the
variational method.


title: Synthetic gauge fields in synthetic dimensions

abstract:
  We describe a simple technique for generating a cold-atom lattice pierced by
a uniform magnetic field. Our method is to extend a one-dimensional optical
lattice into the "dimension" provided by the internal atomic degrees of
freedom, yielding a synthetic 2D lattice. Suitable laser-coupling between these
internal states leads to a uniform magnetic flux within the 2D lattice. We show
that this setup reproduces the main features of magnetic lattice systems, such
as the fractal Hofstadter butterfly spectrum and the chiral edge states of the
associated Chern insulating phases.


title: Lorentz Violation in Top-Quark Physics

abstract:
  Lorentz and CPT violation can affect the rates for $t$-$\ol t$ production and
decay. The Lorentz-violating coefficients in the Standard-Model Extension
responsible for modifying the top-quark events have recently been bounded by
the D0 Collaboration. To extend the analysis to the LHC the calculations need
to be extended to include the gluon fusion production mechanism. Some of the
first results of this program were presented at the Meeting.


title: Strongly Clean Matrices over Commutative Rings

abstract:
  A commutative ring $R$ is projective free provided that every finitely
generated $R$-module is free. An element in a ring is strongly clean provided
that it is the sum of an idempotent and a unit that commutates. Let $R$ be a
projective-free ring, and let $h\in R[t]$ be a monic polynomial of degree $n$.
We prove, in this article, that every $\varphi\in M_n(R)$ with characteristic
polynomial $h$ is strongly clean, if and only if the companion matrix $C_h$ of
$h$ is strongly clean, if and only if there exists a factorization $h=h_0h_1$
such that $h_0\in {\Bbb S}_0, h_1\in {\Bbb S}_1$ and $(h_0,h_1)=1$. Matrices
over power series over projective rings are also discussed. These extend the
known results [1, Theorem 12] and [5, Theorem 25].


title: D+ -> K- pi+ pi+ : heavy meson decays and final state interactions

abstract:
  We show that final state interactions are important in shaping Dalitz plots
for the decay $D^+ \rar K^- \p^+ \p^+$. The theoretical treatment of this
reaction requires a blend of several weak and hadronic processes and hence it
is necessarily involved. In this talk we present results from a calculation
which is still in progress, but has already unveiled the role of important
dynamical mechanisms. We do not consider explicit quark degrees of freedom and
our study is performed within an effective hadronic framework. In spite of the
relatively wide window of energies available in the Dalitz plot for the $D^+$
decay, we depart from $SU(3)\times SU(3)$ chiral perturbation theory and extend
its range by means of unitarization. Our present results, which concentrate on
the vector weak vertex, describe qualitative features of the modulus of the
decay amplitude and agrees well with its phase in the elastic region.


title: Some Quantitative Results in Real Algebraic Geometry

abstract:
  Real algebraic geometry is the study of semi-algebraic sets, subsets of
$\R^k$ defined by Boolean combinations of polynomial equalities and
inequalities. The focus of this thesis is to study quantitative results in real
algebraic geometry, primarily upper bounds on the topological complexity of
semi-algebraic sets as measured, for example, by their Betti numbers. Another
quantitative measure of topological complexity which we study is the number of
homotopy types of semi-algebraic sets of bounded description complexity. The
description complexity of a semi-algebraic set depends on the context, but it
is simply some measure of the complexity of the polynomials in the formula
defining the semi-algebraic set (e.g., the degree and number of variables of a
polynomial, the so called dense format). We also provide a description of the
Hausdorff limit of a one-parameter family of semi-algebraic sets, up to
homotopy type which the author hopes will find further use in the future.
Finally, in the last chapter of this thesis, we prove a decomposition theorem
similar to the well-known cylindrical decomposition for semi-algebraic sets but
which has the advantage of requiring significantly less cells in the
decomposition. The setting of this last result is not in semi-algebraic
geometry, but in the more general setting of o-minimal structures.


title: Type A Molecules are Kazhdan-Lusztig

abstract:
  Let (W, S) be a Coxeter system. A W-graph is an encoding of a representation
of the corresponding Iwahori-Hecke algebra. Especially important examples
include the W-graph corresponding to the action of the Iwahori-Hecke algebra on
the Kazhdan-Lusztig basis, as well as this graph's strongly connected
components (cells). In 2008, Stembridge identified some common features of the
Kazhdan-Lusztig graphs and gave a combinatorial characterization of all
W-graphs that have these features. He conjectured, and checked up to n=9, that
all such A_n-cells are Kazhdan-Lusztig cells. The current paper provides a
first step toward a potential proof of the conjecture. More concretely, we
prove that the connected subgraphs of A_n-cells consisting of simple (i.e.
directed both ways) edges are the same as in the Kazhdan-Lusztig cells.


title:
Using Raster Scans of Bright Stars to Measure the Relative Total
  Throughputs of Cherenkov Telescopes

abstract:
  Gamma-ray astronomy at energies in excess of 100 GeV is carried out using
arrays of imaging Cherenkov telescopes. Each telescope comprises a large
reflector, of order 10 m diameter, made of many mirror facets, and a camera
consisting of a matrix of photomultiplier pixels. Differences in the total
throughput between nominally identical telescopes, due to aging of the mirrors
and PMTs and other effects, should be monitored to reduce possible systematic
errors. One way to directly measure the throughput of such telescopes is to
track bright stars and measure the photocurrents produced by their light
falling on camera pixels. We have developed such a procedure using the four
telescopes in the VERITAS array. We note the technique is general, however, and
could be applied to other imaging Cherenkov experiments. For this measurement,
a raster scan is performed on a single star such that its image is swept across
the central pixels in the camera, thus providing a statistically robust set of
measurements in a short period of time to reduce time-dependent effects on the
throughput. Photocurrents are measured using the starlight-induced baseline
fluctuations of the pixel outputs, as recorded by the standard readout
electronics. In this contribution we describe details of the procedure and
report on feasibility studies carried out during the 2012-2013 observing
season.


title: The inverse deformation problem

abstract:
  We show the inverse deformation problem has an affirmative answer: given a
complete local noetherian ring $A$ with finite residue field $\pmb{k}$, we show
that there is a topologically finitely generated profinite group $\Gamma$ and
an absolutely irreducible continuous representation $\bar\rho:\Gamma\to
GL_n(\pmb{k})$ such that $A$ is the universal deformation ring for
$\Gamma,\bar\rho$.


title: Turbulence model for simulation of the flame front propagation in SNIa

abstract:
  Turbulence significantly influences the dynamics of flame in SNIa. The large
Reynolds number makes impossible the direct numerical simulations of
turbulence, and different models of turbulence have to be used. Here we present
the simulations with the $k$-$\epsilon$ model. The turbulence is generated by
the RTL instability and crucially influences flame front velocity, resulting in
$v_{\rm flame}\sim 300$ km/s. The model reproduces turbulent properties in
low-dimensional simulations and can be used for the low-cost studies.


title: In-situ measurements of whole-dish reflectivity for VERITAS

abstract:
  The VERITAS array is a set of four imaging atmospheric Cherenkov telescopes
(IACTs) sensitive to gamma rays at energies between 85 GeV and 30 TeV. Each
telescope is based on a tessellated mirror, 12 metres in diameter, which
reflects light from a gamma-ray-induced air shower to form an image on a
pixellated `camera' comprising 499 photomultiplier tubes. The image brightness
is the primary measure of the gamma ray's energy so a knowledge of the mirror
reflectivity is important. We describe here a method, pioneered by members of
the MAGIC collaboration, to measure the whole-dish reflectivity, quickly and
regularly, so that effects of aging can be monitored. A CCD camera attached
near the centre of the dish simultaneously acquires an image of both a target
star and its reflection on a target of Spectralon, a highly-reflective
material, placed at the focus of the telescope. The ratio of their
brightnesses, as recorded by the CCD, along with geometric factors, provides an
estimate of the dish reflectivity with few systematic errors. A filter wheel is
placed in front of the CCD camera, allowing to measure the reflectivity as a
function of wavelength. We present initial results obtained with the VERITAS
telescopes during 2012.


title: Geometric properties of semitube domains

abstract:
  In the paper we study the geometry of semitube domains in $\mathbb C^2$. In
particular, we extend the result of Burgu\'es and Dwilewicz for semitube
domains dropping out the smoothness assumption. We also prove various
properties of non-smooth pseudoconvex semitube domains obtaining among others a
relation between pseudoconvexity of a semitube domain and the number of
connected components of its vertical slices.
  Finally, we present an example showing that there is a non-convex domain in
$\mathbb C^n$ such that its image under arbitrary isometry is pseudoconvex.


title:
The VERITAS Upgraded Telescope-Level Trigger Systems: Technical Details
  and Performance Characterization

abstract:
  VERITAS is an array of imaging atmospheric Cherenkov telescopes sensitive to
gamma rays in the energy range between 85 GeV and 30 TeV. The instrument
underwent an upgrade of the camera triggers in November 2011. The new systems
use 400 MHz Xilinix Virtex-5 FPGAs for the pixel neighbor coincidence logic
necessary to produce a camera-level trigger. The upgraded systems are capable
of time-aligning individual triggering pixels to within ~0.2 nanoseconds,
allowing for an operational pixel-to-pixel coincidence window of ~5
nanoseconds. This reduced coincidence window provides improved rejection of
night-sky background (NSB) which permits a reduction of the energy threshold at
the trigger level. The use of FPGAs allows for the future implementation of a
topological trigger capable of discriminating events based on an image moment
analysis of a bit-wise hit pattern. As part of the commissioning phase for the
trigger upgrade, the hardware was initially installed in a single telescope in
"parallel" to the (then) current system. This allowed for the detailed
performance characterization of the new system relative to the pre-existing
trigger. Here we present technical details of the upgraded VERITAS camera
trigger system and outline the details of these performance studies.


title: Muon Identification with VERITAS using the Hough Transform

abstract:
  Imaging atmospheric Cherenkov telescope (IACT) arrays such as VERITAS are
used for ground-based very high-energy gamma-ray astronomy. This is
accomplished by the detection and analysis of the Cherenkov light produced by
gamma-ray-initiated atmospheric air showers. IACTs also detect the Cherenkov
light emitted by individual muons. Identification of these muons is useful
because their Cherenkov light can be used to calibrate the telescopes. Muons
create characteristic annular patterns in the cameras of IACTs, which may be
identified using parametrization algorithms. One such algorithm, the Hough
transform, has been successfully used to identify muons in VERITAS data.
Details of this technique are presented here, including results regarding its
effectiveness.


title: Beam heat load in superconducting wigglers

abstract:
  The beam heat load is a fundamental input parameter for the design of
superconducting wigglers since it is needed to specify the cooling power. In
this presentation I will review the possible beam heat load sources and the
measurements of beam heat load performed and planned onto the cold vacuum
chambers installed at different synchrotron light sources.


title:
Energy space entanglement spectrum of pairing models with s-wave and
  p-wave symmetry

abstract:
  Entanglement between blocks of energy-levels is analysed for systems
exhibiting s-wave and p-wave superconductivity. We study the entanglement
entropy and spectrum of a block of $\ell$ levels around the Fermi point, and
also between particles and holes, in the ground state of Richardson-type
Hamiltonians. The maximal entropy grows with the number of levels $L$
approximately as $1/2\log(L)$, as suggested by the permutational symmetry of
the state at large coupling. The number of levels in the block around the Fermi
surface with maximal entanglement is proposed as a measure of the number of
{\em active Cooper pairs}, which correlates with standard estimates of this
magnitude. The entanglement spectrum is always composed of a principal
parabolic band plus {\em higher bands} whose disappearance signals a exact BCS
state, e.g. in the Moore-Read line, while the Read-Green quantum phase
transition is characterized by a maximum in their weight.


title:
Stationary discs for smooth hypersurfaces of finite type and finite jet
  determination

abstract:
  We construct a finitely dimensional invariant manifold of holomorphic discs
attached to a certain class of smooth pseudconvex hypersurfaces of finite type
in $\C^2$, generalizing the notion of stationary discs. The discs we construct
are determined by a finite jet at a given boundary point and their centers fill
an open set. As a consequence, we obtain a finite jet determination result for
this class of smooth hypersurfaces.


title: Kaluza-Klein reduction of relativistic fluids and their gravity duals

abstract:
  We study the hydrodynamics of relativistic fluids with several conserved
global charges (i.e., several species of particles) by performing a
Kaluza-Klein dimensional reduction of a neutral fluid on a N-torus. Via
fluid/gravity correspondence, this allows us to describe the long-wavelength
dynamics of black branes with several Kaluza-Klein charges. We obtain the
equation of state and transport coefficients of the charged fluid directly from
those of the higher-dimensional neutral fluid. We specialize these results for
the fluids dual to Kaluza-Klein black branes.


title:
Characteristic Direction Approach to Identify Differentially Expressed
  Genes

abstract:
  Genome-wide gene expression profiles, as measured with microarrays or RNA-Seq
experiments, have revolutionized biological and biomedical research by
providing a quantitative measure of the entire mRNA transcriptome. Typically,
researchers set up experiments where control samples are compared to a
treatment condition, and using the t-test they identify differentially
expressed genes upon which further analysis and ultimately biological discovery
from such experiments is based. Here we describe an alternative geometrical
approach to identify differentially expressed genes. We show that this
alternative method, called the Characteristic Direction, is capable of
identifying more relevant genes. We evaluate our approach in three case
studies. In the first two, we match transcription factor targets determined by
ChIP-seq profiling with differentially expressed genes after the same
transcription factor knockdown or over-expression in mammalian cells. In the
third case study, we evaluate the quality of enriched terms when comparing
normal epithelial cells with cancer stem cells. In conclusion, we demonstrate
that the Characteristic Direction approach is much better in calling the
significantly differentially expressed genes and should replace the widely
currently in used t-test method for this purpose. Implementations of the method
in MATLAB, Python and Mathematica are available at:
http://www.maayanlab.net/CD.


title: Dark Matter Annihilation Limits from Dwarf Galaxies using VERITAS

abstract:
  Current cosmological models and data suggest the existence of a cold Dark
Matter (DM) component, however the nature of DM particles remains unknown. A
favored candidate for DM is a Weakly Interacting Massive Particle (WIMP) in the
mass range of 50 GeV to greater than 10 TeV. Nearby dwarf spheroidal galaxies
(dSphs) are expected to contain a high density of DM with a low gamma-ray
background, and are thus promising targets for the detection of secondary gamma
rays at very high energies (VHE, E > 0.1 TeV) through the annihilation of WIMPs
into Standard Model (SM) particles. The VERITAS array of Imaging Atmospheric
Cherenkov Telescopes (IACTs), sensitive to gamma rays in the 100GeV to 50 TeV
range, carries out an extensive observation program of dSphs. Presented here
are results of the observations and new statistical techniques for constraining
properties of WIMP DM models.


title:
Arrays of carbon nanoscrolls as deep-subwavelength magnetic
  metamaterials

abstract:
  We demonstrate theoretically that an array of carbon nanoscrolls acts as a
hyperbolic magnetic metamaterial in the THz regime with genuine subwavelength
operation corresponding to wavelength-to-structure ratio of about 200. Due to
the low sheet resistance of graphene, the electromagnetic losses in an array of
carbon nanoscrolls are almost negligible offering a very sharp magnetic
resonance of extreme positive and negative values of the effective magnetic
permeability. The latter property leads to superior imaging properties for
arrays of carbon nanoscrolls which can operate as magnetic endoscopes in the
THz where magnetic materials are scarce. Our optical modelling is supplemented
with ab initio density-functional calculations of the self-winding of a single
layer of graphene onto a carbon nanotube so as to form a carbon nanoscroll. The
latter process is viewed as a means to realize ordered arrays of carbon
nanoscrolls in the laboratory based on arrays of aligned carbon nanotubes which
are nowadays routinely fabricated.


title: Estimating mean survival time: when is it possible?

abstract:
  For right censored survival data, it is well known that the mean survival
time can be consistently estimated when the support of the censoring time
contains the support of the survival time. In practice, however, this condition
can be easily violated because the follow-up of a study is usually within a
finite window. In this article we show that the mean survival time is still
estimable from a linear model when the support of some covariate(s) with
nonzero coefficient(s) is unbounded regardless of the length of follow-up. This
implies that the mean survival time can be well estimated when the covariate
range is wide in practice. The theoretical finding is further verified for
finite samples by simulation studies. Simulations also show that, when both
models are correctly specified, the linear model yields reasonable mean square
prediction errors and outperforms the Cox model, particularly with heavy
censoring and short follow-up time.


title: On trivialities of Chern classes

abstract:
  A finite $CW$-complex $X$ is $C$-trivial if for every complex vector bundle
$\xi$ over $X$, the total Chern class $c(\xi)=1$. In this note we completely
determine when each of the following spaces are $C$-trivial: suspensions of
stunted real projective spaces, suspensions of stunted complex projective
spaces and suspensions of stunted quaternionic projective spaces.


title:
The Power of Localization for Efficiently Learning Linear Separators
  with Noise

abstract:
  We introduce a new approach for designing computationally efficient learning
algorithms that are tolerant to noise, and demonstrate its effectiveness by
designing algorithms with improved noise tolerance guarantees for learning
linear separators.
  We consider both the malicious noise model and the adversarial label noise
model. For malicious noise, where the adversary can corrupt both the label and
the features, we provide a polynomial-time algorithm for learning linear
separators in $\Re^d$ under isotropic log-concave distributions that can
tolerate a nearly information-theoretically optimal noise rate of $\eta =
\Omega(\epsilon)$. For the adversarial label noise model, where the
distribution over the feature vectors is unchanged, and the overall probability
of a noisy label is constrained to be at most $\eta$, we also give a
polynomial-time algorithm for learning linear separators in $\Re^d$ under
isotropic log-concave distributions that can handle a noise rate of $\eta =
\Omega\left(\epsilon\right)$.
  We show that, in the active learning model, our algorithms achieve a label
complexity whose dependence on the error parameter $\epsilon$ is
polylogarithmic. This provides the first polynomial-time active learning
algorithm for learning linear separators in the presence of malicious noise or
adversarial label noise.


title: Helioseismology from SODISM and HMI Intensity Images

abstract:
  Continuum intensity images from PICARD/SODISM and SDO/HMI covering a 209 days
period in 2011 are analyzed in order to extract mode parameters for spherical
harmonics up to $l=100$. SODISM helioseismology signal is affected by the low
orbit of PICARD and by important gaps and CCD persistence effects. SODISM
intensity signal has a lower signal to noise ratio and duty cycle than HMI and
less modes were successfully fitted over the same period. A comparison of the
rotation profiles obtained from both sets of continuum images shows however
that the results remain compatible within one standard deviation of HMI formal
errors.


title:
On the lattice structure of weakly continuous operators on the space of
  measures

abstract:
  Consider the lattice of bounded linear operators on the space of Borel
measures on a Polish space. We prove that the operators which are continuous
with respect to the weak topology induced by the bounded measurable functions
form a sublattice that is lattice isomorphic to the space of transition
kernels. As an application we present a purely analytic proof of Doob's theorem
concerning stability of transition semigroups.


title: Diffuse Molecular Cloud Densities from UV Measurements of CO Absorption

abstract:
  We use UV measurements of interstellar CO towards nearby stars to calculate
the density in the diffuse molecular clouds containing the molecules
responsible for the observed absorption. Chemical models and recent
calculations of the excitation rate coefficients indicate that the regions in
which CO is found have hydrogen predominantly in molecular form. We carry out
statistical equilibrium calculations using CO-H2 collision rates to solve for
the H2 density in the observed sources without including effects of radiative
trapping. We have assumed kinetic temperatures of 50 K and 100 K, finding this
choice to make relatively little difference to the lowest transition. For the
sources having T_ex(1-0) only, for which we could determine upper and lower
density limits, we find <n(H2)> = 49 cm-3. While we can find a consistent
density range for a good fraction of the sources having either two or three
values of the excitation temperature, there is a suggestion that the higher-J
transitions are sampling clouds or regions within diffuse molecular cloud
material that have higher densities than the material sampled by the J = 1-0
transition. The assumed kinetic temperature and derived H2 density are
anticorrelated when the J = 2-1 transition data, the J = 3-2 transition data,
or both are included. For sources with either two or three values of the
excitation temperature, we find average values of the midpoint of the density
range that is consistent with all of the observations equal to 68 cm-3 for T_k
= 100 K and 92 cm-3 for T_k = 50 K. The data for this set of sources imply that
diffuse molecular clouds are characterized by an average thermal pressure
between 4600 and 6800 Kcm-3.


title:
Simulation of sharp interface multi-material flows involving an
  arbitrary number of components through an extended five-equation model

abstract:
  In this paper, we present an anti-diffusive method dedicated to the
simulation of interface flows on Cartesian grids involving an arbitrary number
m of compress- ible components. Our work is two folds. First, we introduce a
m-component flow model that generalizes a classic two material five-equation
model. In that way, interfaces are localized thanks to color function
discontinuities and a pres- sure equilibrium closure law is used to complete
this new model. The resulting model is demonstrated to be hyperbolic under
simple assumptions and consis- tent. Second, we present a discretization
strategy for this model relying on an Lagrange-Remap scheme. Here, the
projection step involves an anti-dissipative mechanism allowing to prevent
numerical diffusion of the material interfaces. The proposed solver is built
ensuring in one hand consistency and stability properties and in other hand
that the sum of the color functions remains equal to one. The resulting scheme
is first order accurate and conservative for the mass, momentum, energy and
partial masses. Furthermore, the obtained dis- cretization preserves Riemann
invariants as pressure and velocity at the inter- faces. Finally, validation
computations of this numerical method are performed on several tests in one and
two dimensions. The accuracy of the method is also compared to results obtained
by the upwind Lagrange-Remap scheme.


title:
Quartz Capillary Cladding Anthracene and Polycyclic Aromatic
  Hydrocarbon(PAH)-Core Scintillating/WLS Fibers for High Rates and Radiation
  Damage Resistance

abstract:
  Quartz capillary tube/fibers have been filled with anthracene by a melt and
vacuum inbibition process to fabricate a scintillating core fiber. Other
polcyclic aromatic hydrocarbons(PAH), such as p-Terphenyl (pTP), stilbene or
naphthalene are also well-suited to scintillating/shifting fiber cores. The
resulting scintillating core with quartz cladding capillary fibers (250-750
micron cores) had a high specific light output when tested with muons (8 p.e.
per MIP). These PAH core quartz capillary cladding scintillating/shifting
optical fibers have the potential of high radiation resistance, fast response,
and are applicable to many energy and intensity frontier experiments.


title: Covariant action for a string in doubled yet gauged spacetime

abstract:
  The section condition in double field theory has been shown to imply that a
physical point should be one-to-one identified with a gauge orbit in the
doubled coordinate space. Here we show the converse is also true, and continue
to explore the idea of `spacetime being doubled yet gauged'. Introducing an
appropriate gauge connection, we construct a string action, with an arbitrary
generalized metric, which is completely covariant with respect to the
coordinate gauge symmetry, generalized diffeomorphisms, world-sheet
diffeomorphisms, world-sheet Weyl symmetry and O(D,D) T-duality. A topological
term previously proposed in the literature naturally arises and a self-duality
condition follows from the equations of motion. Further, the action may couple
to a T-dual background where the Riemannian metric becomes everywhere singular.


title: Non-markovian polariton dynamics in organic strong coupling

abstract:
  Strongly coupled organic systems are characterized by unusually large Rabi
splittings, even in the vacuum state. They show the counter-intuitive feature
of a lifetime of the lower polariton state longer than for all other excited
states. Here we build up a new theoretical framework to understand the dynamics
of such coupled system. In particular, we show that the non-Markovian character
of the relaxation of the dressed organic system explains the long lifetime of
the lower polariton state.


title:
Analysis and Modeling of Microstructured Fiber Using The Analytical
  Method Based on The Empirical Equation

abstract:
  In this paper, a new class of optical fibers is studied, i.e. microstructured
fibers or photonic crystal fibers (PCF). The main objective is to characterize
these fibers using different dispersion diagrams and present an interface that
enables calculation of various transverse indexes. The choice of these profiles
was guided by a simplification achievement. Furthermore, in order to acquire
expertise in air-silica microstructured fibers, a behavior modeling of these
particular structures is proposed in this paper in order to present an
analytical method based on empirical equations. The fibers treated in this
paper have a triangular arrangement of holes corresponding to the natural
arrangement of a bundle of cylindrical tubes around a central rod of the same
diameter.


title:
A 20 GHz Bright Sample for Delta > 72 deg - II. Multi-frequency
  Follow-up

abstract:
  We present follow-up observations at 5, 8 and 30 GHz of the K-band Northern
Wide Survey (KNoWS) 20 GHz Bright Sample, performed with the 32-m Medicina
Radio Telescope and the 32-m Torun Radio Telescope. The KNoWS sources were
selected in the Northern Polar Cap (Delta > 72 deg) and have a flux density
limit S(20GHz) = 115 mJy. We include NVSS 1.4 GHz measurements to derive the
source radio spectra between 1.4 and 30 GHz. Based on optical identifications,
68 per cent of the sources are QSOs, and 27 per cent are radio galaxies. A
redshift measurement is available for 58 per cent of the sources. The radio
spectral properties of the different source populations are found to be in
agreement with those of other high-frequency selected samples.


title: On the asymptotics of a Robin eigenvalue problem

abstract:
  The considered Robin problem can formally be seen as a small perturbation of
a Dirichlet problem. However, due to the sign of the impedance value, its
associated eigenvalues converge point-wise to $-\infty$ as the perturbation
goes to zero. We prove that in this case, Dirichlet eigenpairs are the only
accumulation points of the Robin eigenpairs with normalized eigenvectors. We
then provide a criteria to select accumulating sequences of eigenvalues and
eigenvectors and exhibit their full asymptotic with respect to the small
parameter.


title: Lorentz Invariance Violation Limits from the Crab Pulsar using VERITAS

abstract:
  Quantum gravity (QG) theories over the past fifty years have sought to
understand the relationship between the four fundamental interactions. A major
insight gained in this area is that all interactions could possibly unify at
Planck-scale energies ~10$^{19}$ GeV. A potential consequence of the
unification of gravity with the other three interactions would be a breaking of
Lorentz symmetry at Planck-scale energies. The interpretation of Time-of-flight
(TOF) measurements from gamma-ray telescopes have been able to put constraints
on the energy scales of the Lorentz-invariance violations (LIV). The Crab
pulsar, the only pulsar detected at very high energies (VHE, E > 100 GeV)
presents a unique opportunity to put new constraints on LIV. Presented here are
the results of observations of the Crab pulsar with VERITAS and statistical
methods to determine limits of LIV effects from energy-dependent timing
differences.


title:
Confluence of singularities of non-linear differential equations via
  Borel--Laplace transformations

abstract:
  Borel summable divergent series usually appear when studying solutions of
analytic ODE near a multiple singular point. Their sum, uniquely defined in
certain sectors of the complex plane, is obtained via the Borel--Laplace
transformation. This article shows how to generalize the Borel--Laplace
transformation in order to investigate bounded solutions of parameter dependent
non-linear differential systems with two simple (regular) singular points
unfolding a double (irregular) singularity. We construct parametric solutions
on domains attached to both singularities, that converge locally uniformly to
the sectoral Borel sums. Our approach provides a unified treatment for all
values of the complex parameter.


title:
A Thorough Investigation of Distance and Age of the Pulsar Wind Nebula
  3C58

abstract:
  A growing number of researchers present evidence that the pulsar wind nebula
3C58 is much older than predicted by its proposed connection to the historical
supernova of A.D. 1181. There is also a great diversity of arguments. The
strongest of these arguments rely heavily on the assumed distance of 3.2 kpc
determined with HI absorption measurements. This publication aims at
determining a more accurate distance for 3C58 and re-evaluating the arguments
for a larger age. I have re-visited the distance determination of 3C58 based on
new HI data from the Canadian Galactic Plane Survey and our recent improvements
in the knowledge of the rotation curve of the outer Milky Way Galaxy. I have
also used newly determined distances to objects in the neighbourhood, which are
based on direct measurements by trigonometric parallax. I have derived a new
more reliable distance estimate of 2 kpc for 3C58. This makes the connection
between the pulsar wind nebula and the historical event from A.D. 1181 once
again much more viable.


title: A simple technique for steganography

abstract:
  A new technique for data hiding in digital image is proposed in this paper.
Steganography is a well known technique for hiding data in an image, but
generally the format of image plays a pivotal role in it, and the scheme is
format dependent. In this paper we will discuss a new technique where
irrespective of the format of image, we can easily hide a large amount of data
without deteriorating the quality of the image. The data to be hidden is
enciphered with the help of a secret key. This enciphered data is then embedded
at the end of the image. The enciphered data bits are extracted and then
deciphered with the help of same key used for encryption. Simulation results
show that Image Quality Measures of this proposed scheme are better than the
conventional LSB replacing technique. The proposed method is simple and is easy
to implement.


title:
Intersections of the Hermitian surface with irreducible quadrics in
  $PG(3,q^2)$, $q$ odd

abstract:
  In $PG(3,q^2)$, with $q$ odd, we determine the possible intersection sizes of
a Hermitian surface $\mathcal{H}$ and an irreducible quadric $\mathcal{Q}$
having the same tangent plane $\pi$ at a common point $P\in{\mathcal
Q}\cap{\mathcal H}$.


title:
Abstract commensurators of right-angled Artin groups and mapping class
  groups

abstract:
  We prove that, aside from the obvious exceptions, the mapping class group of
a compact orientable surface is not abstractly commensurable with any
right-angled Artin group. Our argument applies to various subgroups of the
mapping class group---the subgroups generated by powers of Dehn twists and the
terms of the Johnson filtration---and additionally to the outer automorphism
group of a free group and to certain linear groups.


title: A global analytic critical equations of state

abstract:
  We propose a general form for global analytic equations of state for which
close to critical points, the correct universality and scaling behavior is
guaranteed.
  A consequence of the construction is that the generally accepted belief that
the dependent scaling field cannot be written as an explicit function of the
relevant scaling fields without causing strongly singular behavior of the
thermodynamic potential in the one-phase region, while in agreement with the
state of the art in the past, is no longer correct.


title:
Proceedings of the 13th International Colloquium on Implementation of
  Constraint and LOgic Programming Systems

abstract:
  This volume contains the proceedings of the 13th International Colloquium on
Implementation of Constraint and LOgic Programming Systems (CICLOPS 2013), held
in Istanbul, Turkey during August 25, 2013. CICLOPS is a well established line
of workshops, traditionally co-located with ICLP, that aims at discussing and
exchanging experience on the design, implementation, and optimization of
constraint and logic programming systems, and other systems based on logic as a
means of expressing computations. This year, CICLOPS received 8 paper
submissions. Each submission was reviewed by at least 3 Program Committee
members and, at the end, 6 papers were accepted for presentation at the
workshop. We would like to thank the ICLP organizers for their support, the
EasyChair conference management system for making the life of the program
chairs easier and arxiv.org for providing permanent hosting. Thanks should go
also to the authors of all submitted papers for their contribution to make
CICLOPS alive and to the participants for making the event a meeting point for
a fruitful exchange of ideas and feedback on recent developments. Finally, we
want to express our gratitude to the Program Committee members, as the
symposium would not have been possible without their dedicated work.


title: Electroweak Monopole Production at the LHC - a Snowmass White Paper

abstract:
  We maintain that the search for the electroweak monopole is a key issue in
the advancement of our understanding of the standard model. Unlike the Dirac
monopole in electrodynamics, which is optional, the electroweak monopole should
exist within the framework of the standard model. The mass of the electroweak
monopole is estimated to be 5 to 7 TeV, but could be as large as 15 TeV. Above
threshold its production rate at the LHC is expected to be relatively large,
(1/alpha(em)2) times bigger than that of W+W- pairs. The search for the
electroweak monopole is one of the prime motivations of the newest LHC
experiment, MoEDAL, which is due to start data taking in 2015.


title: A multi-phase, multi-component critical equation of state

abstract:
  Realistic equations of state valid in the whole state space of a
multi-component mixture should satisfy at least three important constraints:
(i) The Gibbs phase rule holds. (ii) At low densities, one can deduce a virial
equation of state with the correct multi-component structure. (iii) Close to
critical points, plait points, and consolute points, the correct universality
and scaling behavior is guaranteed.
  This paper discusses semiempirical equations of state for mixtures that
express the pressure as an explicit function of temperature and the chemical
potentials. In the first part, expressions are derived for the most important
thermodynamic quantities. The main result of the second part is the
construction of a large family of equations of state with the properties
(i)--(iii).


title: Giant spin oscillations in an ultracold Fermi sea

abstract:
  Collective behavior in many-body systems is the origin of many fascinating
phenomena in nature ranging from swarms of birds and modeling of human behavior
to fundamental magnetic properties of solids. We report on the first
observation of collective spin dynamics in an ultracold Fermi sea with large
spin: We observe long-lived and large-amplitude coherent spin oscillations,
driven by local spin interactions. At ultralow temperatures, Pauli blocking
stabilizes the collective behavior and the Fermi sea behaves as a single entity
in spin space. With increasing temperature, we observe a stronger damping
associated with particle-hole excitations. As a striking feature, we find a
high-density regime where excited spin configurations are collisionally
stabilized.


title:
Femtosecond dynamics of magnetic excitations from resonant inelastic
  x-ray scattering in CaCu2O3

abstract:
  Taking spinon excitations in the quantum antiferromagnet CaCu2O3 as an
example, we demonstrate that femtosecond dynamics of magnetic excitations can
be probed by direct resonant inelastic x-ray scattering (RIXS). To this end, we
isolate the contributions of single and double spin-flip excitations in
experimental RIXS spectra, identify the physical mechanisms that cause them and
determine their respective timescales. By comparing theory and experiment, we
find that double spin flips need a finite amount of time to be generated,
rendering them sensitive to the core-hole lifetime, whereas single spin flips
are to a very good approximation independent of it. This shows that RIXS can
grant access to time-domain dynamics of excitations and illustrates how RIXS
experiments can distinguish between excitations in correlated electron systems
based on their different time dependence.


title: Cosmic ray Spectrum, Composition, and Anisotropy Measured with IceCube

abstract:
  Analysis of cosmic ray surface data collected with the IceTop array of
Cherenkov detectors at the South Pole provides an accurate measurement of the
cosmic ray spectrum and its features in the "knee" region up to energies of
about 1 EeV. IceTop is part of the IceCube Observatory that includes a deep-ice
cubic kilometer detector that registers signals of penetrating muons and other
particles. Surface and in-ice signals detected in coincidence provide clear
insights into the nuclear composition of cosmic rays. IceCube already measured
an increase of the average primary mass as a function of energy. We present
preliminary results on both IceTop-only and coincident event analyses.
Furthermore, we review the recent measurement of the cosmic ray anisotropy with
IceCube.


title:
Statistical and other properties of Riemann zeros based on an explicit
  equation for the $n$-th zero on the critical line

abstract:
  We show that there are an infinite number of Riemann zeros on the critical
line, enumerated by the positive integers $n=1,2,\dotsc$, whose ordinates can
be obtained as the solution of a new transcendental equation that depends only
on $n$. Under weak assumptions, we show that the number of such zeros already
saturates the counting formula for the numbers of zeros on the entire critical
strip. These results thus constitute a concrete proposal toward verifying the
Riemann hypothesis. We perform numerical analyses of the exact equation, and
its asymptotic limit of large ordinate. The starting point is an explicit
analytical formula for an approximate solution to the exact equation in terms
of the Lambert $W$ function. In this way, we neither have to use Gram points or
deal with violations of Gram's law. Our numerical approach thus constitutes a
novel method to compute the zeros. Employing these numerical solutions, we
verify that solutions of the asymptotic version are accurate enough to confirm
Montgomery's and Odlyzko's pair correlation conjectures and also to reconstruct
the prime number counting function.


title: Cauchy-Davenport type theorems for semigroups

abstract:
  Let $\mathbb{A} = (A, +)$ be a (possibly non-commutative) semigroup. For $Z
\subseteq A$ we define $Z^\times := Z \cap \mathbb A^\times$, where $\mathbb
A^\times$ is the set of the units of $\mathbb{A}$, and $$\gamma(Z) := \sup_{z_0
\in Z^\times} \inf_{z_0 \ne z \in Z} {\rm ord}(z - z_0).$$ The paper
investigates some properties of $\gamma(\cdot)$ and shows the following
extension of the Cauchy-Davenport theorem: If $\mathbb A$ is cancellative and
$X, Y \subseteq A$, then $$|X+Y| \ge \min(\gamma(X+Y),|X| + |Y| - 1).$$ This
implies a generalization of Kemperman's inequality for torsion-free groups and
strengthens another extension of the Cauchy-Davenport theorem, where
$\mathbb{A}$ is a group and $\gamma(X+Y)$ in the above is replaced by the
infimum of $|S|$ as $S$ ranges over the non-trivial subgroups of $\mathbb{A}$
(Hamidoune-K\'arolyi theorem).


title: Sirius and the project of the megalithic enclosures at Gobekli Tepe

abstract:
  The megalithic enclosures of Gobekli Tepe (Urfa, Turkey) are the most ancient
sacred structures of stone known so far, dating back to the 10 millennium BC.
The possible presence of astronomical targets for these structures is analysed,
and it turns out that they may have been oriented, or even originally
constructed, to celebrate and successively follow the appearance of a new,
extremely brilliant star in the southern skies: Sirius.


title:
Synchronization in Phase-Coupled Kuramoto Oscillator Networks with
  Axonal Delay and Synaptic Plasticity

abstract:
  We explore both analytically and numerically an ensemble of coupled
phase-oscillators governed by a Kuramoto-type system of differential equations.
However, we have included the effects of time-delay (due to finite
signal-propagation speeds) and network plasticity (via dynamic coupling
constants) inspired by the Hebbian learning rule in neuroscience. When
time-delay and learning effects combine, novel synchronization phenomena are
observed. We investigate the formation of spatio-temporal patterns in both one-
and two-dimensional oscillator lattices with periodic boundary conditions and
comment on the role of dimensionality.


title:
All chalcogenide Raman parametric Laser, Wavelength Converter and
  Amplifier in a Single Microwire

abstract:
  Compact, power efficient and fiber compatible lasers, wavelength converters
and amplifiers are vital ingredients for the future fiber optic systems and
networks. Nonlinear optical effects, like Raman scattering and parametric four
wave mixing, offer a way to realize such devices. Here we use a single
chalcogenide microwire to realize a device that provides the functions of a
Stokes Raman parametric laser, a four wave mixing anti Stokes wavelength
converter, and an ultra broadband Stokes/anti Stokes Raman amplifier or
supercontinuum generator. The device operation relies on ultrahigh Raman and
Kerr gain (upto five orders of magnitude larger than in silica fibers),
precisely engineered chromatic dispersion and high photosensitivity of the
chalcogenide microwire. The Raman parametric laser operates at a record low
threshold average (peak) pump power of 52 \muW (207 mW) and a slope efficiency
of >2%. A powerful anti Stokes signal is generated via the nonlinear four wave
mixing process. As amplifier or the broadband source, the device covers a
wavelength (frequency) range of >330 nm (47 THz) when pumped at a wavelength of
1550 nm. Owing to the underlying principle of operation of the device being the
nonlinear optical processes, the device is anticipated to operate over the
entire transmission window of the chalcogenide glass ({\lambda}~1 10 \mum).


title: Dedekind complete posets from sheaves on von Neumann algebras

abstract:
  We show that for any two von Neumann algebras $M$ and $N$, the space of
non-unital normal homomorphisms $N\to M$ with finite support, modulo
conjugation by unitaries in $M$, is Dedekind complete with respect to the
partial order coming from the addition of homomorphisms with orthogonal ranges;
this ties in with work by Brown and Capraro, where the corresponding objects
are given Banach space structures under various niceness conditions on $M$ and
$N$. More generally, we associate to $M$ a Grothendieck site-type category, and
show that presheaves satisfying a sheaf-like condition on this category give
rise to Dedekind complete lattices upon modding out unitary conjugation.
Examples include the above-mentioned spaces of morphisms, as well as analogous
spaces of completely positive or contractive maps. We also study conditions
under which these posets can be endowed with cone structures extending their
partial additions.


title: FpSynt: a fixed-point datapath synthesis tool for embedded systems

abstract:
  Digital mobile systems must function with low power, small size and weight,
and low cost. High-performance desktop microprocessors, with built-in floating
point hardware, are not suitable in these cases. For embedded systems, it can
be advantageous to implement these calculations with fixed point arithmetic
instead. We present an automated fixed-point data path synthesis tool FpSynt
for designing embedded applications in fixed-point domain with sufficient
accuracy for most applications. FpSynt is available under the GNU General
Public License from the following GitHub repository:
http://github.com/izhbannikov/FPSYNT


title:
Inverse Scattering with Partial data on Asymptotically Hyperbolic
  Manifolds

abstract:
  We prove that the scattering matrix at all energies restricted to an open
subset of the boundary determines an asymptotically hyperbolic manifold modulo
isometries that are equal to the identity on the open subset where the
scattering matrix is known.


title: A statistical view on exchanges in Quickselect

abstract:
  In this paper we study the number of key exchanges required by Hoare's FIND
algorithm (also called Quickselect) when operating on a uniformly distributed
random permutation and selecting an independent uniformly distributed rank.
After normalization we give a limit theorem where the limit law is a perpetuity
characterized by a recursive distributional equation. To make the limit theorem
usable for statistical methods and statistical experiments we provide an
explicit rate of convergence in the Kolmogorov--Smirnov metric, a numerical
table of the limit law's distribution function and an algorithm for exact
simulation from the limit distribution. We also investigate the limit law's
density. This case study provides a program applicable to other cost measures,
alternative models for the rank selected and more balanced choices of the pivot
element such as median-of-$2t+1$ versions of Quickselect as well as further
variations of the algorithm.


title: Congruences of fork extensions of slim semimodular lattices

abstract:
  For a slim, planar, semimodular lattice $L$ and covering square~$S$,
G.~Cz\'edli and E.\,T.~Schmidt introduced the fork extension, $L[S]$, which is
also a slim, planar, semimodular lattice. We investigate when a congruence of
$L$ extends to $L[S]$.
  We introduce a join-irreducible congruence $\boldsymbol{\gamma}(S)$ of
$L[S]$. We determine when it is new, in the sense that it is not generated by a
join-irreducible congruence of $L$. When it is new, we describe the congruence
$\boldsymbol{\gamma}(S)$ in great detail. The main result follows: \emph{In the
order of join-irreducible congruences of a slim, planar, semimodular lattice
$L$, the congruence $\boldsymbol{\gamma}(S)$ has \emph{at most two covers.}}


title: Who and Where: People and Location Co-Clustering

abstract:
  In this paper, we consider the clustering problem on images where each image
contains patches in people and location domains. We exploit the correlation
between people and location domains, and proposed a semi-supervised
co-clustering algorithm to cluster images. Our algorithm updates the
correlation links at the runtime, and produces clustering in both domains
simultaneously. We conduct experiments in a manually collected dataset and a
Flickr dataset. The result shows that the such correlation improves the
clustering performance.


title: High-fidelity gates in quantum dot spin qubits

abstract:
  Several logical qubits and quantum gates have been proposed for semiconductor
quantum dots controlled by voltages applied to top gates. The different schemes
can be difficult to compare meaningfully. Here we develop a theoretical
framework to evaluate disparate qubit-gating schemes on an equal footing. We
apply the procedure to two types of double-dot qubits: the singlet-triplet (ST)
and the semiconducting quantum dot hybrid qubit. We investigate three quantum
gates that flip the qubit state: a DC pulsed gate, an AC gate based on logical
qubit resonance (LQR), and a gate-like process known as stimulated Raman
adiabatic passage (STIRAP). These gates are all mediated by an exchange
interaction that is controlled experimentally using the interdot tunnel
coupling $g$ and the detuning $\epsilon$, which sets the energy difference
between the dots. Our procedure has two steps. First, we optimize the gate
fidelity ($f$) for fixed $g$ as a function of the other control parameters;
this yields an $f^\text{opt}(g)$ that is universal for different types of
gates. Next, we identify physical constraints on the control parameters; this
yields an upper bound $f^\text{max}$ that is specific to the qubit-gate
combination. We show that similar gate fidelities ($ \sim 99.5$%) should be
attainable for ST qubits in isotopically purified Si, and for hybrid qubits in
natural Si. Considerably lower fidelities are obtained for GaAs devices, due to
the fluctuating magnetic fields $\Delta B$ produced by nuclear spins.


title:
SlopMap: a software application tool for quick and flexible
  identification of similar sequences using exact k-mer matching

abstract:
  With the advent of Next-Generation (NG) sequencing, it has become possible to
sequence an entire genome quickly and inexpensively. However, in some
experiments one only needs to extract and assembly a portion of the sequence
reads, for example when performing transcriptome studies, sequencing
mitochondrial genomes, or characterizing exomes. With the raw DNA-library of a
complete genome it would appear to be a trivial problem to identify reads of
interest. But it is not always easy to incorporate well-known tools such as
BLAST, BLAT, Bowtie, and SOAP directly into a bioinformatics pipelines before
the assembly stage, either due to in- compatibility with the assembler's file
inputs, or because it is desirable to incorporate information that must be
extracted separately. For example, in order to incorporate flowgrams from a
Roche 454 sequencer into the Newbler assembler it is necessary to first extract
them from the original SFF files. We present SlopMap, a bioinformatics software
utility which allows rapid identification similar to provided target sequences
from either Roche 454 or Illumnia DNA library. With a simple and intuitive
command- line interface along with file output formats compatible with assembly
programs, SlopMap can be directly embedded in biological data processing
pipeline without any additional programming work. In addition, SlopMap
preserves flowgram information needed for Roche 454 assembler.


title: The Fourier transform of multiradial functions

abstract:
  We obtain an exact formula for the Fourier transform of multiradial
functions, i.e., functions of the form $\Phi(x)=\phi(|x_1|, \dots, |x_m|)$,
$x_i\in \mathbf R^{n_i}$, in terms of the Fourier transform of the function
$\phi$ on $\mathbf R^{r_1}\times \cdots \times \mathbf R^{r_m}$, where $r_i$ is
either 1 or 2.


title:
How user throughput depends on the traffic demand in large cellular
  networks

abstract:
  Little's law allows to express the mean user throughput in any region of the
network as the ratio of the mean traffic demand to the steady-state mean number
of users in this region. Corresponding statistics are usually collected in
operational networks for each cell. Using ergodic arguments and Palm theoretic
formalism, we show that the global mean user throughput in the network is equal
to the ratio of these two means in the steady state of the "typical cell".
Here, both means account for double averaging: over time and network geometry,
and can be related to the per-surface traffic demand, base-station density and
the spatial distribution of the SINR. This latter accounts for network
irregularities, shadowing and idling cells via cell-load equations. We validate
our approach comparing analytical and simulation results for Poisson network
model to real-network cell-measurements.


title:
Analysis of a Proportionally Fair and Locally Adaptive spatial Aloha in
  Poisson Networks

abstract:
  The proportionally fair sharing of the capacity of a Poisson network using
Spatial-Aloha leads to closed-form performance expressions in two extreme
cases: (1) the case without topology information, where the analysis boils down
to a parametric optimization problem leveraging stochastic geometry; (2) the
case with full network topology information, which was recently solved using
shot-noise techniques. We show that there exists a continuum of adaptive
controls between these two extremes, based on local stopping sets, which can
also be analyzed in closed form. We also show that these control schemes are
implementable, in contrast to the full information case which is not. As local
information increases, the performance levels of these schemes are shown to get
arbitrarily close to those of the full information scheme. The analytical
results are combined with discrete event simulation to provide a detailed
evaluation of the performance of this class of medium access controls.


title: Stepsize control for Newton's method in the presence of singularities

abstract:
  Singularities in the Jacobian matrix are an obstacle to Newton's method. We
show that stepsize controls suggested by Deuflhard and Steinhoff can be used to
detect and rapidly converge to such singularities.


title: On a result of D.W. Stroock

abstract:
  We show how to modify an argument of D. W. Stroock to show that an additive
map from one separable Banach space to another, that is "universally Gaussian
measurable", must be continuous (hence linear).


title: Young Brown Dwarfs as Giant Exoplanet Analogs

abstract:
  Young brown dwarfs and directly-imaged exoplanets have enticingly similar
photometric and spectroscopic characteristics, indicating that their cool, low
gravity atmospheres should be studied in concert. Similarities between the
peculiar shaped H band, near and mid-IR photometry as well as location on color
magnitude diagrams provide important clues about how to extract physical
properties of planets from current brown dwarf observations. In this proceeding
we discuss systems newly assigned to 10-150 Myr nearby moving groups, highlight
the diversity of this uniform age-calibrated brown dwarf sample, and reflect on
their implication for understanding current and future planetary data.


title:
A Herman-Avila-Bochi formula for higher dimensional pseudo-unitary and
  hermitian-symplectic cocycles

abstract:
  A Herman-Avila-Bochi type formula is obtained for the average sum of the top
d Lyapunov exponents over a one-parameter family of G-cocycles, where G is the
group that leaves a certain, non-degenerate hermitian form of signature (c,d)
invariant. The generic example of such a group is the pseudo-unitary group
U(c,d) or in the case c=d, the hermitian-symplectic group HSp(2d) which
naturally appears for cocycles related to Schr\"odinger operators. In the case
d=1, the formula for HSp(2d) cocycles reduces to the Herman-Avila-Bochi formula
for SL(2,R) cocycles.


title: Periodic free resolutions from twisted matrix factorizations

abstract:
  The notion of a matrix factorization was introduced by Eisenbud in the
commutative case in his study of bounded (periodic) free resolutions over
complete intersections. In this work, we extend the notion of (homogeneous)
matrix factorizations to regular normal elements of connected graded algebras
over a field.
  Next, we relate the category of twisted matrix factorizations to an element
over a ring and certain Zhang twists. We also show that in the AS-regular
setting, every sufficiently high syzygy module is the cokernel of some twisted
matrix factorization. Furthermore, we show that in this setting there is an
equivalence of categories between the homotopy category of twisted matrix
factorizations and the singularity category of the hypersurface, following work
of Orlov.


title: Improving the Gutzwiller Ansatz with Matrix Product States

abstract:
  The Gutzwiller variational wavefunction (GVW) is commonly employed to capture
correlation effects in condensed matter systems such as ferromagnets, ultracold
bosonic gases, correlated superconductors, etc. By noticing that the
grand-canonical and number-conserving Gutzwiller Ans\"atze are in fact the
zero-order approximation of an expansion in the truncation parameter of a
Matrix Product State (MPS), we argue that MPSs, and the algorithms used to
operate on them, are not only flexible computational tools but also a unifying
theoretical framework that can be used to generalize and improve on the GVW. In
fact, we show that a number-conserving GVW is less efficient in capturing the
ground state of a quantum system than a more general MPS which can be optimized
with comparable computational resources. Moreover, we suggest a corrected
time-dependent density matrix renormalization group algorithm that ensures the
conservation of the expectation value of the number of particles when a GVW or
a MPS are not explicitly number-conserving. The GVW dynamics obtained with our
algorithm compares very well with the exact one in 1D. Most importantly, the
algorithm works in any dimension for a GVW. We thus expect it to be of great
value in the study of the dynamics of correlated quantum systems.


title:
Wigner distribution functions for complex dynamical systems: the
  emergence of the Wigner-Boltzmann equation

abstract:
  The equation of motion for the reduced Wigner function of a system coupled to
an external quantum system is presented for the specific case when the external
quantum system can be modeled as a set of harmonic oscillators. The result is
derived from the Wigner function formulation of the Feynman-Vernon influence
functional theory. It is shown how the true self-energy for the equation of
motion is connected with the influence functional for the path integral.
Explicit expressions are derived in terms of the bare Wigner propagator.
Finally, we show under which approximations the resulting equation of motion
reduces to the Wigner-Boltzmann equation.


title: Dynamical systems and categories

abstract:
  We study questions motivated by results in the classical theory of dynamical
systems in the context of triangulated and A-infinity categories. First,
entropy is defined for exact endofunctors and computed in a variety of
examples. In particular, the classical entropy of a pseudo-Anosov map is
recovered from the induced functor on the Fukaya category. Second, the density
of the set of phases of a Bridgeland stability condition is studied and a
complete answer is given in the case of bounded derived categories of quivers.
Certain exceptional pairs in triangulated categories, which we call Kronecker
pairs, are used to construct stability conditions with density of phases. Some
open questions and further directions are outlined as well.


title: A note on extensions of nilpotent algebras of Type 2

abstract:
  We propose the study and description of the structure of complex Lie algebras
with nilradical a nilpotent Lie algebra of type 2 by using
sl2(C)-representation theory. Our results will be applied to review the
classification given in [1] (J. Geometry and Physics, 2011) of the Lie algebras
with nilradical the quasiclassical algebra L5;3. A non-Lie algebra has been
erroneously included in this classification. The 5-dimensional Lie algebra L5;3
is a free nilpotent algebra of type 2 and it is one of two free nilpotent
algebras admitting an invariant metric. According to [, Ok98] quasiclassical
algebras let construct consistent Yang-Mills gauge theories.


title:
Role of vector and pseudoscalar mesons in understanding $1/2^-$ $N^*$
  and $\Delta$ resonances

abstract:
  A study of nonstrange meson-baryon systems has been made with the idea of
understanding the properties of the low-lying $1/2^-$ $N^*$ and $\Delta$
resonances. The coupled channels are built by considering the pseudoscalar and
vector mesons together with the octet baryons. The formalism is based on
obtaining the interactions from the lowest order chiral Lagrangian when dealing
with pseudoscalar mesons and relying on the hidden local symmetry in case of
the vector mesons. The transition between the two systems is obtained by
replacing the photon by a vector meson in the Kroll-Ruderman theorem for the
photoproduction of pseudoscalar mesons. The subtraction constants, required to
calculate the loop-function in the scattering equations, are constrained by
fitting the available experimental data on some of the reactions with
pseudoscalar meson-baryon final states. As a consequence, we find resonances
which can be related to $N^*(1535)$, $N^*(1650)$ (with a double pole
structure), $N^*(1895)$ and $\Delta(1620)$. We conclude that these resonances
can be, at least partly, interpreted as dynamically generated resonances and
that the vector mesons play an important role in determining the dynamical
origin of the low-lying $N^*$ and $\Delta$ states.


title:
Fermi Rules Out the IC/CMB Model for the Large Scale Jet X-ray Emission
  of 3C 273

abstract:
  The X-ray emission mechanism in large-scale jets of powerful radio quasars
has been a source of debate in recent years, with two competing
interpretations: either the X-rays are of synchrotron origin, arising from a
different electron energy distribution than that producing the radio to optical
synchrotron component, or they are due to inverse Compton scattering of cosmic
microwave background photons (IC/CMB) by relativistic electrons in a powerful
relativistic jet with bulk Lorentz factor Gamma ~ 10-20. These two models imply
radically different conditions in the large-scale jet in terms of jet speed,
kinetic power, and maximum energy of the particle acceleration mechanism, with
important implications for the impact of the jet on the large-scale
environment. A large part of the X-ray origin debate has centered on the
well-studied source 3C 273. Here we present new observations from Fermi which
put an upper limit on the gamma-ray flux from the large-scale jet of 3C 273
that violates at a confidence greater that 99.9% the flux expected from the
IC/CMB X-ray model found by extrapolation of the UV to X-ray spectrum of knot
A, thus ruling out the IC/CMB interpretation entirely for this source when
combined with previous work. Further, this upper limit from Fermi puts a limit
on the Doppler beaming factor of at least delta < 9, assuming equipartition
fields, and possibly as low as delta < 5, assuming no major deceleration of the
jet from knots A through D1.


title:
Detection of Equatorward Meridional Flow and Evidence of Double-Cell
  Meridional Circulation inside the Sun

abstract:
  Meridional flow in the solar interior plays an important role in
redistributing angular momentum and transporting magnetic flux inside the Sun.
Although it has long been recognized that the meridional flow is predominantly
poleward at the Sun's surface and in its shallow interior, the location of the
equatorward return flow and the meridional flow profile in the deeper interior
remain unclear. Using the first two years of continuous helioseismology
observations from the Solar Dynamics Observatory / Helioseismic Magnetic
Imager, we analyze travel times of acoustic waves that propagate through
different depths of the solar interior carrying information about the solar
interior dynamics. After removing a systematic center-to-limb effect in the
helioseismic measurements and performing inversions for flow speed, we find
that the poleward meridional flow of a speed of 15 m/s extends in depth from
the photosphere to about 0.91 R_sun. An equatorward flow of a speed of 10 m/s
is found between 0.82 to 0.91 R_sun in the middle of the convection zone. Our
analysis also shows evidence of that the meridional flow turns poleward again
below 0.82 R_sun, indicating an existence of a second meridional circulation
cell below the shallower one. This double-cell meridional circulation profile
with an equatorward flow shallower than previously thought suggests a
rethinking of how magnetic field is generated and redistributed inside the Sun.


title: A hypergraph Tur\'an theorem via lagrangians of intersecting families

abstract:
  Let $\mc{K}_{3,3}^3$ be the 3-graph with 15 vertices $\{x_i, y_i: 1 \le i \le
3\}$ and $\{z_{ij}: 1 \le i,j \le 3\}$, and 11 edges $\{x_1, x_2, x_3\}$,
$\{y_1, y_2, y_3\}$ and $\{\{x_i, y_j, z_{ij}\}: 1 \le i,j \le 3\}$. We show
that for large $n$, the unique largest $\mc{K}_{3,3}^3$-free 3-graph on $n$
vertices is a balanced blow-up of the complete 3-graph on 5 vertices. Our proof
uses the stability method and a result on lagrangians of intersecting families
that has independent interest.


title:
Phase space hybrid theory of quantum measurement with nonlinear and
  stochastic dynamics

abstract:
  A novel theory of hybrid quantum-classical systems is developed, utilizing
the mathematical framework of constrained dynamical systems on the
quantum-classical phase space. Both, the quantum and the classical descriptions
of the respective parts of the hybrid system are treated as fundamental.
Therefore, the description of the quantum-classical interaction has to be
postulated, and includes the effects of neglected degrees of freedom. Dynamical
law of the theory is given in terms of nonlinear stochastic differential
equations with Hamiltonian and gradient terms. The theory provides a successful
dynamical description of the collapse during quantum measurement.


title: Subtraction-free complexity, cluster transformations, and spanning trees

abstract:
  Subtraction-free computational complexity is the version of arithmetic
circuit complexity that allows only three operations: addition, multiplication,
and division.
  We use cluster transformations to design efficient subtraction-free
algorithms for computing Schur functions and their skew, double, and
supersymmetric analogues, thereby generalizing earlier results by P. Koev.
  We develop such algorithms for computing generating functions of spanning
trees, both directed and undirected. A comparison to the lower bound due to M.
Jerrum and M. Snir shows that in subtraction-free computations, "division can
be exponentially powerful."
  Finally, we give a simple example where the gap between ordinary and
subtraction-free complexity is exponential.


title:
Integration with respect to L\'evy colored noise, with applications to
  SPDEs

abstract:
  In this article, we introduce a L\'evy analogue of the spatially homogeneous
Gaussian noise of Dalang (1999), and we construct a stochastic integral with
respect to this noise. The spatial covariance of the noise is given by a
tempered measure $\mu$ on $\bR^d$, whose density is given by $|h|^2$ for a
complex-valued function $h$. Without assuming that the Fourier transform of
$\mu$ is a non-negative function, we identify a large class of integrands with
respect to this noise. As an application, we examine the linear stochastic heat
and wave equations driven by this type of noise.


title: Multiwavelength Observations of the SS 433 Jets

abstract:
  We present observations of the SS 433 jets using the Chandra High Energy
Transmission Grating Spectrometer with contemporaneous optical and VLBA
observations. The X-ray and optical emission line regions are found to be
related but not coincident as the optical line emission persists for days while
the X-ray emission lines fade in less than 5000 s. The line Doppler shifts from
the optical and X-ray lines match well, indicating that they are less than 3e14
cm apart. The jet Doppler shifts show aperiodic variations that could result
from shocks in interactions with the local environment. These perturbations are
consistent with a change in jet direction but not jet speed. The proper motions
of the radio knots match the kinematic model only if the distance to SS 433 is
4.5 +/- 0.2 kpc. Observations during eclipse show that the occulted emission is
very hard, seen only above 2 keV and rising to comprise >50% of the flux at 8
keV. The soft X-ray emission lines from the jet are not blocked, constraining
the jet length to >~ 2e12 cm. The base jet density is in the range
1e(10-13)/cm^3, in contrast to our previous estimate based on the Si XIII
triplet, which is likely to have been affected by UV de-excitation. There is a
clear overabundance of Ni by a factor of about 10 relative to the solar value,
which may have resulted from an unusual supernova that formed the compact
object.


title: Classical scale-invariance, the electroweak scale and vector dark matter

abstract:
  We consider a classically scale-invariant extension of the standard model in
which a dark, non-Abelian gauge symmetry is spontaneously broken via the
Coleman-Weinberg mechanism. Higgs portal couplings between the dark and
standard model sectors provide an origin for the Higgs mass squared parameter
and, hence, the electroweak scale. We find that choices for model parameters
exist in which the dark gauge multiplet is viable as dark matter.


title: The intersection of bivariate orthogonal polynomials on triangle patches

abstract:
  In this paper, the intersection of bivariate orthogonal polynomials on
triangle patches will be investigated. The result is interesting by its own but
also has important applications in the theory of a posteriori error estimation
for finite element discretizations with $p$-refinement, i.e., if the local
polynomial degree of the test and trial functions is increased to improve the
accuracy. A triangle patch is a set of disjoint open triangles whose closed
union covers a neighborhood of the common triangle vertex. On each triangle we
consider the space of orthogonal polynomials of degree n with respect to the
weight function which is the product of the barycentric coordinates. We show
that the intersection of these polynomial spaces is the null space. The
analysis requires the derivation of subtle representations of orthogonal
polynomials on triangles. Up to four triangles have to be considered to
identify that the intersection is trivial.


title: Fast Simultaneous Training of Generalized Linear Models (FaSTGLZ)

abstract:
  We present an efficient algorithm for simultaneously training sparse
generalized linear models across many related problems, which may arise from
bootstrapping, cross-validation and nonparametric permutation testing. Our
approach leverages the redundancies across problems to obtain significant
computational improvements relative to solving the problems sequentially by a
conventional algorithm. We demonstrate our fast simultaneous training of
generalized linear models (FaSTGLZ) algorithm on a number of real-world
datasets, and we run otherwise computationally intensive bootstrapping and
permutation test analyses that are typically necessary for obtaining
statistically rigorous classification results and meaningful interpretation.
Code is freely available at http://liinc.bme.columbia.edu/fastglz.


title: Analogue gravity in hyperbolic metamaterials

abstract:
  Sub-wavelength confinement of light in nonlinear hyperbolic metamaterials due
to formation of spatial solitons has attracted much recent attention because of
its seemingly counter-intuitive behavior. In order to achieve self-focusing in
a hyperbolic wire medium, a nonlinear self-defocusing Kerr medium must be used
as a dielectric host. Here we demonstrate that this behavior finds natural
explanation in terms of analogue gravity. Wave equation describing propagation
of extraordinary light inside hyperbolic metamaterials exhibits 2+1 dimensional
Lorentz symmetry. The role of time in the corresponding effective 3D Minkowski
spacetime is played by the spatial coordinate aligned with the optical axis of
the metamaterial. Nonlinear optical Kerr effect bends this spacetime resulting
in effective gravitational force between extraordinary photons. In order for
the effective gravitational constant to be positive, negative self-defocusing
Kerr medium must be used as a host. If gravitational self-interaction is strong
enough, spatial soliton may collapse into a black hole analogue.


title: Partially Directed Snake Polyominoes

abstract:
  The goal of this paper is to study the family of snake polyominoes. More
precisely, we focus our attention on the class of partially directed snakes. We
establish functional equations and length generating functions of two
dimensional, three dimensional and then $N$ dimensional partially directed
snake polyominoes. We then turn our attention to partially directed snakes
inscribed in a $b\times k$ rectangle and we establish two-variable generating
functions, with respect to height $k$ and length $n$ of the snakes. We include
observations on the relationship between snake polyominoes and self-avoiding
walks. We conclude with a discussion on inscribed snakes polyominoes of maximal
length which lead us to the formulation of a conjecture encountered in the
course of our investigations.


title:
Analytical families of 2-component anisotropic polytropes and their
  relativistic extensions

abstract:
  In this paper, we study a family of two-component anisotropic polytropes
which model a wide range of spherically symmetric astrophysical systems such as
early-type baryonic galaxies. This family is found to contain a large class of
models such as the hypervirial family (which satisfy the virial theorem
locally), the Plummer and Hernquist models and Navarro-Frenk-White (NFW)-like
models. The potential--density pair for these models are derived, as well as
their velocity dispersions and anisotropy parameters. The projected quantities
are computed and found to reduce to analytical expressions in some cases. The
first section of this paper presents an extension of the two-term anisotropic
polytropes to encompass a very wide range of potential-density pairs. In the
next section, we present the general relativistic extension of the
potential-density pair, and calculate the stress-energy tensor, the
relativistic anisotropy parameter, the velocity of circular orbits and the
angular momentum. Remarkably, for the case of the hypervirial family, the
relativistic pressure in the Newtonian limit and the relativistic anisotropy
parameter are found to coincide with the corresponding Newtonian expressions.
The weak, dominant and strong energy conditions are found to be satisfied only
for a certain range of the free parameters. We show that the relativistic
hypervirial family also has a finite total mass like its Newtonian counterpart.
In the first appendix, a relativistic extension of a different hypervirial
family of models is studied, and the relativistic anisotropy parameter is found
to coincide with the Newtonian one. Finally, we present a family of models
obtained from our distribution function that are similar to the
Ossipkov-Merritt models; by computing their anisotropy parameters, we show that
they model systems with isotropic cores and radially anisotropic exteriors.


title:
Progenitors of supernova Ibc: a single Wolf-Rayet star as the possible
  progenitor of the SN Ib iPTF13bvn

abstract:
  Core-collapse supernova (SN) explosions mark the end of the tumultuous life
of massive stars. Determining the nature of their progenitors is a crucial step
towards understanding the properties of SNe. Until recently, no progenitor has
been directly detected for SN of type Ibc, which are believed to come from
massive stars that lose their hydrogen envelope through stellar winds and from
binary systems where the companion has stripped the H envelope from the
primary. Here we analyze recently reported observations of iPTF13bvn, which
could possibly be the first detection of a SN Ib progenitor based on
pre-explosion images. Very interestingly, the recently published Geneva models
of single stars can reproduce the observed photometry of the progenitor
candidate and its mass-loss rate, confirming a recently proposed scenario. We
find that a single WR star with initial mass in the range 31-35 Msun fits the
observed photometry of the progenitor of iPTF13bvn. The progenitor likely has a
luminosity of log (L/Lsun)~5.55, surface temperature ~45000 K, and mass of
~10.9 Msun at the time of explosion. Our non-rotating 32 Msun model
overestimates the derived radius of the progenitor, although this could likely
be reconciled with a fine-tuned model of a more massive (between 40 and 50
Msun), hotter, and luminous progenitor. Our models indicate a very uncertain
ejecta mass of ~8 Msun, which is higher than the average of the SN Ib ejecta
mass that is derived from the lightcurve (2-4 Msun). This possibly high ejecta
mass could produce detectable effects in the iPTF13bvn lightcurve and spectrum.
If the candidate is indeed confirmed to be the progenitor, our results suggest
that stars with relatively high initial masses (>30 Msun) can produce visible
SN explosions at their deaths and do not collapse directly to a black hole.

categories: astro-ph.SR astro-ph.CO astro-ph.GA astro-ph.HE


title: Unveiling shocks in planetary nebulae

abstract:
  The propagation of a shock wave into a medium is expected to heat the
material beyond the shock, producing noticeable effects in intensity line
ratios such as [O III]/Halpha. To investigate the occurrence of shocks in
planetary nebulae (PNe), we have used all narrowband [O III] and Halpha images
of PNe available in the HST archive to build their [O III]/Halpha ratio maps
and to search for regions where this ratio is enhanced. Regions with enhanced
[O III]/Halpha emission ratio can be ascribed to two different types of
morphological structures: bow-shock structures produced by fast collimated
outflows and thin skins enveloping expanding nebular shells. Both collimated
outflows and expanding shells are therefore confirmed to generate shocks in
PNe. We also find regions with depressed values of the [O III]/Halpha ratio
which are found mostly around density bounded PNe, where the local contribution
of [N II] emission into the F656N Halpha filter cannot be neglected.