title: Red Supergiants in the Local Group

abstract:
  Galaxies in the Local Group span a factor of 15 in metallicity, ranging from
the super-solar M31 to the Wolf-Lundmark-Melotte (WLM) galaxy, which is the
lowest-metallicity (0.1xZsun) Local Group galaxy currently forming stars.
Studies of massive star populations across this broad range of environments
have revealed important metallicity-dependent evolutionary trends, allowing us
to test the accuracy of stellar evolutionary tracks at these metallicities for
the first time. The RSG population is particularly valuable as a key
mass-losing phase of moderately massive stars and a source of core-collapse
supernova progenitors. By reviewing recent work on the RSG populations in the
Local Group, we are able to quantify limits on these stars' effective
temperatures and masses and probe the relationship between RSG mass loss
behaviors and host environments. Extragalactic surveys of RSGs have also
revealed several unusual RSGs that display signs of unusual spectral
variability and dust production, traits that may potentially also correlate
with the stars' host environments. I will present some of the latest work that
has progressed our understanding of RSGs in the Local Group, and consider the
many new questions posed by our ever-evolving picture of these stars.


title: \alpha-concave functions and a functional extension of mixed volumes

abstract:
  Mixed volumes, which are the polarization of volume with respect to the
Minkowski addition, are fundamental objects in convexity. In this note we
announce the construction of mixed integrals, which are functional analogs of
mixed volumes. We build a natural addition operation + on the class of
quasi-concave functions, such that every class of \alpha-concave functions is
closed under +. We then define the mixed integrals, which are the polarization
of the integral with respect to +.
  We proceed to discuss the extension of various classic inequalities to the
functional setting. For general quasi-concave functions, this is done by
restating those results in the language of rearrangement inequalities.
Restricting ourselves to \alpha-concave functions, we state a generalization of
the Alexandrov inequalities in their more familiar form.


title:
Unobstructedness of filling secants and the Gruson-Peskine general
  projection theorem

abstract:
  We prove an unobstructedness result for deformations of subvarieties
constrained by intersections with another, fixed subvariety. We deduce
smoothness and expected-dimension results for multiple-point loci of generic
projections, mainly from a point or a line, or for fibres of embedding
dimension 2 or less. The current version is a substantial enhancement of the
previous one, including for the first time results on projection from a line.


title: Weitzenboeck derivations of free metabelian Lie algebras

abstract:
  A nonzero locally nilpotent linear derivation of the polynomial algebra K[X]
in d variables over a field K of characteristic 0 is called a Weitzenboeck
derivation. The classical theorem of Weitzenboeck states that the algebra of
constants (which coincides with the algebra of invariants of a single unipotent
transformation) is finitely generated. Similarly one may consider the algebra
of constants of a locally nilpotent linear derivation of a finitely generated
(not necessarily commutative or associative) algebra which is relatively free
in a variety of algebras over K. Now the algebra of constants is usually not
finitely generated. Except for some trivial cases this holds for the algebra of
constants of the free metabelian Lie algebra L/L" with d generators. We show
that the vector space of the constants in the commutator ideal L'/L" is a
finitely generated module over the algebra of constants in K[X]. For small d,
we calculate the Hilbert series of the algebra of constants in L/L" and find
the generators of the module of the constants in L'/L". This gives also an
(infinite) set of generators of the Lie algebra of constants in L/L".


title: Collective properties of cellular identity: a computational approach

abstract:
  Cell type (e.g. pluripotent cell, fibroblast) is the end result of many
complex processes that unfold due to evolutionary, developmental, and
transformational stimuli. A cell's phenotype and the discrete, a priori states
that define various cell subtypes (e.g. skin fibroblast, embryonic stem cell)
are ultimately part of a continuum that may predict changes and systematic
variation in cell subtypes. These features can be both observable in existing
cellular states and hypothetical (e.g. unobserved). In this paper, a series of
approaches will be used to approximate the continuous diversity of gene
expression across a series of pluripotent, totipotent, and fibroblast cellular
subtypes. We will use a series of previously-collected datasets and analyze
them using three complementary approaches: the computation of distances based
on the subsampling of diversity, assessing the separability of individual genes
for a specific cell line both within and between cell types, and a hierarchical
soft classification technique that will assign a membership value for specific
genes in specific cell types given a number of different criteria. These
approaches will allow us to assess the observed gene-expression diversity in
these datasets, as well as assess how well a priori cell types characterize
their constituent populations. In conclusion, the application of these findings
to a broader biological context will be discussed.


abstract:
  We derive the Landau energy levels for twisted N-enlarged Newton-Hooke
space-time, i.e. we find the time-dependent energy spectrum and the
corresponding eigenstates for an electron moving in uniform magnetic as well as
in uniform electric external fields.


title: Separating principles below Ramsey's Theorem for Pairs

abstract:
  In recent years, there has been a substantial amount of work in reverse
mathematics concerning natural mathematical principles that are provable from
$\RT$, Ramsey's Theorem for Pairs. These principles tend to fall outside of the
"big five" systems of reverse mathematics and a complicated picture of
subsystems below $\RT$ has emerged. In this paper, we answer two open questions
concerning these subsystems, specifically that $\ADS$ is not equivalent to
$\CAC$ and that $\EM$ is not equivalent to $\RT$.


title:
Topological properties of the continuous function spaces on some ordered
  compacta

abstract:
  Some new classes of compacta $K$ are considered for which $C(K)$ endowed with
the pointwise topology has a countable cover by sets of small local
norm--diameter.


title:
Combination of the top-quark mass measurements from the Tevatron and
  from the LHC colliders

abstract:
  I present here the results for the combination of the top-quark mass (mt)
measurements at the Tevatron and at the LHC. These combinations are based on
measurements using up to 5.8 fb-1 from CDF and D0 yielding mt=173.18 +-
0.56(stat) +- 0.75(syst) GeV, and up to 4.7 fb-1 from ATLAS and CMS leading to
mt=173.3 +-0.5(stat) +-1.3(syst) GeV.


title: Quantum mechanical model for J/psi suppression in the LHC era

abstract:
  We discuss the interplay of screening, absorption and regeneration effects,
on the quantum mechanical evolution of quarkonia states, within a
time-dependent harmonic oscillator (THO) model with complex oscillator
strength. We compare the results with data for R_AA/R_AA(CNM) from CERN and
RHIC experiments. In the absence of a measurement of cold nuclear matter (CNM)
effects at LHC we estimate their role and interpret the recent data from the
ALICE experiment. We also discuss the temperature dependence of the real and
imaginary parts of the oscillator frequency which stand for screening and
absorption/regeneration, respectively. We point out that a structure in the
J/psi suppression pattern for In-In collisions at SPS is possibly related to
the recently found X(3872) state in the charmonium spectrum. Theoretical
support for this hypothesis comes from the cluster expansion of the plasma
Hamiltonian for heavy quarkonia in a strongly correlated medium.


title: The intrinsic bispectrum of the Cosmic Microwave Background

abstract:
  We develop a new, efficient code for solving the second-order
Einstein-Boltzmann equations, and use it to estimate the intrinsic CMB
non-Gaussianity arising from the non-linear evolution of density perturbations.
The full calculation involves contributions from recombination and less
tractable contributions from terms integrated along the line of sight. We
investigate the bias that this intrinsic bispectrum implies for searches of
primordial non-Gaussianity. We find that the inclusion or omission of certain
line of sight terms can make a large impact. When including all physical
effects but lensing and time-delay, we find that the local-type f_nl would be
biased by f_nl ~ 0.5, below the expected sensitivity of the Planck satellite.
The speed of our code allows us to confirm the robustness of our results with
respect to a number of numerical parameters.


title: \beta-Mn: Emergent Simplicity in a Complex Structure

abstract:
  We investigate low-temperature spin correlations in the metallic frustrated
magnet \beta-MnCo. Single-crystal polarised-neutron scattering experiments
reveal the persistence of highly-structured magnetic diffuse scattering and the
absence of periodic magnetic order to T=0.05 K. We employ reverse Monte Carlo
refinements and mean-field theory simulations to construct a simple effective
Hamiltonian which accounts for the magnetic scattering. The interactions we
identify describe an emergent spin structure which mimics the triangular
lattice antiferromagnet. The observation of a simple collective magnetic state
in a complicated crystal structure is surprising because it reverses the
established paradigm of elaborate emergent states arising from many-body
interactions on simple lattices. We suggest that structural complexity may
provide a route to realising new states of correlated quantum matter.


title: Scaling Theory of Heat Transport in Quasi-1D Disordered Harmonic Chains

abstract:
  We introduce a variant of the Banded Random Matrix ensemble and show, using
detailed numerical analysis and theoretical arguments, that the phonon heat
current in disordered quasi-one-dimensional lattices obeys a one-parameter
scaling law. The resulting beta-function indicates that an anomalous Fourier
law is applicable in the diffusive regime, while in the localization regime the
heat current decays exponentially with the sample size. Our approach opens a
new way to investigate the effects of Anderson localization in heat conduction,
based on the powerful ideas of scaling theory.


title: Estimate of the weight of empty space based on astronomical observations

abstract:
  As a consequence of the equivalence principle and of the existence of a
negative vacuum energy, we show how a weak but universal linear response of the
vacuum to a local gravitational potential suffices to explain the main features
of so-called Pioneer anomalies as well as the apparent departure from the third
Kepler law which has been observed at the level of numerous galaxies.


title:
A class of exact solutions of the Li\'enard type ordinary non-linear
  differential equation

abstract:
  A class of exact solutions is obtained for the Li\'{e}nard type ordinary
non-linear differential equation. As a first step in our study the second order
Li\'{e}nard type equation is transformed into a second kind Abel type first
order differential equation. With the use of an exact integrability condition
for the Abel equation (the Chiellini lemma), the exact general solution of the
Abel equation can be obtained, thus leading to a class of exact solutions of
the Li\'{e}nard equation, expressed in a parametric form. We also extend the
Chiellini integrability condition to the case of the general Abel equation. As
an application of the integrability condition the exact solutions of some
particular Li\'{e}nard type equations, including a generalized van der Pol type
equation, are explicitly obtained.


title: Binary population synthesis and SNIa rates

abstract:
  Despite the significance of type Ia supernovae (SNeIa) in many fields in
astrophysics, SNeIa lack a theoretical explanation. We investigate the
potential contribution to the SNeIa rate from the most common progenitor
channels using the binary population synthesis (BPS) code SeBa. Using SeBa, we
aim constrain binary processes such as the common envelope phase and the
efficiency of mass retention of white dwarf accretion. We find that the
simulated rates are not sufficient to explain the observed rates. Further, we
find that the mass retention efficiency of white dwarf accretion significantly
influences the rates, but does not explain all the differences between
simulated rates from different BPS codes.


title:
Longitudinal dielectric permeability into quantum non-degenerate and
  maxwellian plasma with frequency of collisions proportional to the module of
  a wave vector

abstract:
  Formulas for the longitudinal dielectric permeability in quantum
non-degenerate and maxwellian collisional plasma with the frequency of
collisions proportional to the module of the wave vector, in Mermin's approach,
are received. Equation of Shr\"{o}dinger - Boltzmann with integral of
collisions relaxation type in Mermin's approach is applied. It is spent
numerical and graphic comparison of the real and imaginary parts of dielectric
function of non-degenerate and maxwellian collisional quantum plasma with a
constant and a variable frequencies of collisions. It is shown, that the
longitudinal dielectric function weakly depends on a wave vector.


title:
Why Professor Richard Feynman was upset solving the Laplace equation for
  spherical waves?

abstract:
  We take attention to the singular behavior of the Laplace operator in
spherical coordinates, which was established in our earlier work. This
singularity has many non-trivial consequences. In this article we consider only
the simplest ones, which are connected to the solution of Laplace equation in
Feynman classical books and Lectures. Feynman was upset looking in his derived
solutions, which have a fictitious singular behavior at the origin. We show how
these inconsistencies can be avoided.


title: Supersymmetric Cubic Galileons Have Ghosts

abstract:
  Galileons are higher-derivative theories of a real scalar which nevertheless
admit second order equations of motion. They have interesting applications as
dark energy models and in early universe cosmology, and have been conjectured
to arise as descriptions of brane dynamics in string theory. In the present
paper, we study the bosonic sector of globally N=1 supersymmetric extensions of
the cubic Galileon Lagrangian in detail. Supersymmetry requires that the
Galileon scalar now becomes paired with a second real scalar field. We prove
that the presence of this second scalar causes the equations of motion to
become higher than second order, thus leading to the appearance of ghosts. We
also analyze the energy scales up to which, in an effective field theory
description, the ghosts can be tamed.


title: OGLE-2011-BLG-0417: A Radial Velocity Testbed for Microlensing

abstract:
  Microlensing experiments are returning increasingly detailed information
about the planetary and binary systems that are being detected, far beyond what
was originally expected. In several cases the lens mass and distance are
measured, and a few very special cases have yielded complete 8-parameter Kepler
solutions, i.e., the masses of both components, five Kepler invariants and the
phase. We identify one such case that is suitable for a precision test that
could be carried out by comparing Doppler (RV) measurements with the
predictions from the microlensing solution. The lens primary is reasonably
bright (I=16.3, V=18.0) and is expected to have a relatively large RV
semi-amplitude K ~ 6.35 km/s).


title:
X-ray Detections of Sub-millimetre Galaxies: Active Galactic Nuclei
  Versus Starburst Contribution

abstract:
  We present a large-scale study of the X-ray properties and near-IR-to-radio
SEDs of submillimetre galaxies (SMGs) detected at 1.1mm with the AzTEC
instrument across a ~1.2 square degree area of the sky. Combining deep 2-4 Ms
Chandra data with Spitzer IRAC/MIPS and VLA data within the GOODS-N/S and
COSMOS fields, we find evidence for AGN activity in ~14 percent of 271 AzTEC
SMGs, ~28 percent considering only the two GOODS fields. Through X-ray spectral
modeling and SED fitting using Monte Carlo Markov Chain techniques to
Siebenmorgen et al. (2004) (AGN) and Efstathiou et al. (2000) (starburst)
templates, we find that while star formation dominates the IR emission, with
SFRs ~100-1000 M_sun/yr, the X-ray emission for most sources is almost
exclusively from obscured AGNs, with column densities in excess of 10^23 cm^-2.
Only for ~6 percent of our sources do we find an X-ray-derived SFR consistent
with NIR-to-radio SED derived SFRs. Inclusion of the X-ray luminosities as a
prior to the NIR-to-radio SED effectively sets the AGN luminosity and SFR,
preventing significant contribution from the AGN template. Our SED modeling
further shows that the AGN and starburst templates typically lack the required
1.1 mm emission necessary to match observations, arguing for an extended, cool
dust component. The cross correlation function between the full samples of
X-ray sources and SMGs in these fields does not indicate a strong correlation
between the two populations at large scales, suggesting that SMGs and AGNs do
not necessarily trace the same underlying large scale structure. Combined with
the remaining X-ray-dim SMGs, this suggests that sub-mm bright sources may
evolve along multiple tracks, with X-ray-detected SMGs representing
transitionary objects between periods of high star formation and AGN activity
while X-ray-faint SMGs represent a brief starburst phase of more normal
galaxies.


title: Abundance of 26Al and 60Fe in evolving Giant Molecular Clouds

abstract:
  The nucleosynthesis and ejection of radioactive $^{26}$Al (t$_{1/2} \sim$
0.72\,Myr) and $^{60}$Fe, (t$_{1/2} \sim$ 2.5\,Myr) into the interstellar
medium is dominated by the stellar winds of massive stars and supernova type II
explosions. Studies of meteorites and their components indicate that the
initial abundances of these short-lived radionuclides in the solar
protoplanetary disk were higher than the background levels of the galaxy
inferred from $\gamma$--ray astronomy and models of the galactic chemical
evolution. This observation has been used to argue for a late-stage addition of
stellar debris to the Solar System's parental molecular cloud or,
alternatively, the solar protoplanetary disk, thereby requiring a special
scenario for the formation of our Solar System. Here, we use supercomputers to
model---from first principles---the production, transport and admixing of
freshly synthesized $^{26}$Al and $^{60}$Fe in star-forming regions within
giant molecular clouds. Under typical star-formation conditions, the levels of
$^{26}$Al in most star-forming regions are comparable to that deduced from
meteorites, suggesting that the presence of short-lived radionuclides in the
early Solar System is a generic feature of the chemical evolution of giant
molecular clouds. The $^{60}$Fe/$^{26}$Al yield ratio of $\approx 0.2$
calculated from our simulations is consistent with the galactic value of 0.15
$\pm$ 0.06 inferred from $\gamma$--ray astronomy but is significantly higher
than most current Solar System measurements indicate. We suggest that estimates
based on differentiated meteorites and some chondritic components may not be
representative of the initial $^{60}$Fe abundance of the bulk Solar System.


title:
On the effect of the Cosmic Microwave Background in high-redshift
  (sub-)millimeter observations

abstract:
  Modern (sub-)millimeter interferometers enable the measurement of the cool
gas and dust emission of high-redshift galaxies (z>5). However, at these
redshifts the cosmic microwave background (CMB) temperature is higher,
approaching, and even exceeding, the temperature of cold dust and molecular gas
observed in the local Universe. In this paper, we discuss the impact of the
warmer CMB on (sub-)millimeter observations of high-redshift galaxies. The CMB
affects the observed (sub-)millimeter dust continuum and the line emission
(e.g. carbon monoxide, CO) in two ways: (i) it provides an additional source of
(both dust and gas) heating; and (ii) it is a non-negligible background against
which the line and continuum emission are measured. We show that these two
competing processes affect the way we interpret the dust and gas properties of
high-redshift galaxies using spectral energy distribution models. We quantify
these effects and provide correction factors to compute what fraction of the
intrinsic dust (and line) emission can be detected against the CMB as a
function of frequency, redshift and temperature. We discuss implications on the
derived properties of high-redshift galaxies from (sub-)millimeter data.
Specifically, the inferred dust and molecular gas masses can be severely
underestimated for cold systems if the impact of the CMB is not properly taken
into account.


title:
A 1.1 to 1.9 GHz SETI Survey of the Kepler Field: I. A Search for
  Narrow-band Emission from Select Targets

abstract:
  We present a targeted search for narrow-band (< 5 Hz) drifting sinusoidal
radio emission from 86 stars in the Kepler field hosting confirmed or candidate
exoplanets. Radio emission less than 5 Hz in spectral extent is currently known
to only arise from artificial sources. The stars searched were chosen based on
the properties of their putative exoplanets, including stars hosting candidates
with 380 K > T_eq > 230 K, stars with 5 or more detected candidates or stars
with a super-Earth (R_p < 3 R_earth) in a > 50 day orbit. Baseband voltage data
across the entire band between 1.1 and 1.9 GHz were recorded at the Robert C.
Byrd Green Bank Telescope between Feb--Apr 2011 and subsequently searched
offline. No signals of extraterrestrial origin were found. We estimate that
fewer than ~1% of transiting exoplanet systems host technological civilizations
that are radio loud in narrow-band emission between 1-2 GHz at an equivalent
isotropically radiated power (EIRP) of ~1.5 x 10^21 erg s^-1, approximately
eight times the peak EIRP of the Arecibo Planetary Radar, and we limit the the
number of 1-2 GHz narrow-band-radio-loud Kardashev type II civilizations in the
Milky Way to be < 10^-6 M_solar^-1. Here we describe our observations, data
reduction procedures and results.


title: Jet Mass Spectra in Higgs + One Jet at NNLL

abstract:
  The invariant mass of a jet is a benchmark variable describing the structure
of jets at the LHC. We calculate the jet mass spectrum for Higgs plus one jet
at the LHC at next-to-next-to-leading logarithmic (NNLL) order using a
factorization formula. At this order, the cross section becomes sensitive to
perturbation theory at the soft m_jet^2/p_T^jet scale. Our calculation is
exclusive and uses the 1-jettiness global event shape to implement a veto on
additional jets. The dominant dependence on the jet veto is removed by
normalizing the spectrum, leaving residual dependence from non-global
logarithms depending on the ratio of the jet mass and jet veto variables. For
our exclusive jet cross section these non-global logarithms are parametrically
smaller than in the inclusive case, allowing us to obtain a complete NNLL
result. Results for the dependence of the jet mass spectrum on the kinematics,
jet algorithm, and jet size R are given. Using individual partonic channels we
illustrate the difference between the jet mass spectra for quark and gluon
jets. We also study the effect of hadronization and underlying event on the jet
mass in PYTHIA. To highlight the similarity of inclusive and exclusive jet mass
spectra, a comparison to LHC data is presented.


title: Dispersing quasinormal modes in 2+1 dimensional conformal field theories

abstract:
  We study the charge response of conformal field theories (CFTs) at non-zero
temperature in 2+1 dimensions using the AdS/CFT correspondence. A central role
is played by the quasinormal modes (QNMs), specifically, the poles and zeros of
the current correlators. We generalize our recent study of the QNMs of the a.c.
charge conductivity to include momentum dependence. This sheds light on the
various excitations in the CFT. We begin by discussing the R-current
correlators of the N=8 SU(N) super-Yang-Mills theory at its conformal fixed
point using holography. For instance, transitions in the QNM spectrum as a
function of momentum clearly identify hydrodynamic-to-relativistic crossovers.
We then extend our study to include four-derivative terms in the gravitational
description allowing us to study more generic charge response as well as the
role of S-duality, which plays a central role in understanding the correlators.
The presence of dispersing Drude-like QNMs can lead to new behavior, distinct
from what occurs in the aforementioned gauge theory. We also extend previous
conductivity sum rules to finite momentum and discuss their interpretation in
the gravity picture. A comparison is finally made with the conformal fixed
point of the vector O(N) model in the large-N limit.


title:
The Outer Limits of the M31 System: Kinematics of the Dwarf Galaxy
  Satellites And XXVIII and And XXIX

abstract:
  We present Keck/DEIMOS spectroscopy of resolved stars in the M31 satellites
And XXVIII & And XXIX. We show that these are likely self-bound galaxies based
on 18 and 24 members in And XXVIII & And XXIX, respectively. And XXVIII has a
systemic velocity of -331.1 +/- 1.8 km/s and velocity dispersion of 4.9+/-1.6
km/s, implying a mass-to-light ratio (within r_1/2) of ~ 44 +/- 41. And XXIX
has a systemic velocity of -194.4 +/- 1.5 km/s and velocity dispersion of
5.7+/-1.2 km/s, implying a mass-to-light ratio (within r_1/2) of ~ 124 +/- 72.
The internal kinematics and implied masses of And XXVIII & And XXIX are similar
to dwarf spheroidals (dSphs) of comparable luminosities, implying that these
objects are dark matter-dominated dwarf galaxies. Despite the large projected
distances from their host (380 and 188 kpc), the kinematics of these dSph
suggest that they are bound M31 satellites.


title: Caught in the Act: Discovery of a Physical Quasar Triplet

abstract:
  We present the discovery of a triplet of quasars at z~1.51. The whole system
is well accommodated within 25 arcsec (i.e., 200 kpc in projected distance).
The velocity differences among the three objects (as measured through the broad
MgII emission line) are less than 1000 km/s, suggesting that the quasars belong
to the same physical structure. Broad band NIR images of the field do not
reveal evidence of galaxies or galaxy clusters that could act as a
gravitational lens, ruling out the possibility that two or all the three
quasars are multiple images of a single, strongly lensed source. QQQ J1519+0627
is the second triplet of quasars known up to date. We estimate that these
systems are extremely rare in terms of simple accidental superposition. The
lack of strong galaxy overdensity suggests that this peculiar system is
harboured in the seeds of a yet-to-be-formed massive structure.
  Based on observations collected at the La Silla Observatory with the New
Technology Telescope (NTT) of the European Southern Observatory (ESO) and at
the Calar Alto Observatory with the 3.5m telescope of the Centro Astron\'omico
Hispano Alem\'an (CAHA).


title:
Studying Faint Ultra Hard X-ray Emission from AGN in GOALS LIRGs with
  Swift BAT

abstract:
  We present the first analysis of the all-sky Swift BAT ultra hard X-ray
(14-195 keV) data for a targeted list of objects. We find the BAT data can be
studied at 3x fainter limits than in previous blind detection catalogs based on
prior knowledge of source positions and using smaller energy ranges for source
detection. We determine the AGN fraction in 134 nearby (z<0.05) luminous
infrared galaxies (LIRGS) from the GOALS sample. We find that LIRGs have a
higher detection frequency than galaxies matched in stellar mass and redshift
at 14-195 keV and 24-35 keV. In agreement with work at other wavelengths, the
AGN detection fraction increases strongly at high IR luminosity with half of
high luminosity LIRGs (50%, 6/12, log L_IR/L_sun>11.8) detected. The BAT AGN
classification shows 97% (37/38) agreement with Chandra and XMM AGN
classification using hardness ratios or detection of a iron K-alpha line. This
confirms our statistical analysis and supports the use of the Swift BAT all-sky
survey to study fainter populations of any category of sources in the ultra
hard X-ray band. BAT AGN in LIRGs tend to show higher column densities with
40\pm9% showing 14-195 keV/2-10 keV hardness flux ratios suggestive of high or
Compton-thick column densities (log N_H>24 cm^-2), compared to only 12\pm5% of
non-LIRG BAT AGN. We also find that using specific energy ranges of the BAT
detector can yield additional sources over total band detections with 24%
(5/21) of detections in LIRGs at 24-35 keV not detected at 14-195 keV.


title: Spectral Properties of X-ray Binaries in Centaurus A

abstract:
  We present a spectral investigation of X-ray binaries in NGC 5128 (Cen A),
using six 100 ks Chandra observations taken over two months in 2007. We divide
our sample into thermally and non-thermally dominated states based on the
behavior of the fitted absorption column, and present the spectral parameters
of sources with L >2x10^37 erg/s. The majority of sources are consistent with
being neutron star low mass X-ray binaries (NS LMXBs) and we identify three
transient black hole (BH) LMXB candidates coincident with the dust lane, which
is the remnant of a small late-type galaxy. Our results also provide tentative
support for the apparent `gap' in the mass distribution of compact objects
between ~2-5 Msol.
  We propose that BH LMXBs are preferentially found in the dust lane, and
suggest this is because of the younger stellar population. The majority
(~70-80%) of potential Roche-lobe filling donors in the Cen A halo are >12 Gyr
old, while BH LMXBs require donors >1 Msol to produce the observed peak
luminosities. This requirement for more massive donors may also explain recent
results that claim a steepening of the X-ray luminosity function with age at Lx
>= 5x10^38 erg/s for the XB population of early-type galaxies; for older
stellar populations, there are fewer stars >1 Msol, which are required to form
the more luminous sources.


title:
Cosmological Constraints from applying SHAM to rescaled cosmological
  simulations

abstract:
  We place constraints on the matter density of the Universe and the amplitude
of clustering using measurements of the galaxy two-point correlation function
from the Sloan Digital Sky Survey (SDSS). We generate model predictions for
different cosmologies by populating rescaled N-body simulations with galaxies
using the subhalo abundance matching (SHAM) technique. We find Omega-M = 0.29
+/- 0.03 and sigma-8 = 0.86 +/- 0.04 at 68% confidence from fitting the
observed two-point galaxy correlation function of galaxies brighter than M_r =
-18 in a volume limited sample of galaxies obtained by the SDSS. We discuss and
quantify potential sources of systematic error, and conclude that while there
is scope for improving its robustness, the technique presented in this paper
provides a powerful low redshift constraint on the cosmological parameters that
is complementary to other commonly used methods.


title: Thermalization of Causal Holographic Information

abstract:
  We study causal wedges associated with a given sub-region in the boundary of
asymptotically AdS spacetimes. Part of our motivation is to better understand
the recently proposed holographic observable, causal holographic information
(CHI), which is given by the area of a bulk co-dimension two surface lying on
the boundary of the causal wedge. It has been suggested that CHI captures the
basic amount of information contained in the reduced density matrix about the
bulk geometry. To explore its properties further we examine its behaviour in
time-dependent situations. As a simple model we focus on null dust collapse in
an asymptotically AdS spacetime, modeled by the Vaidya-AdS geometry. We argue
that while CHI is generically quasi-telelogical in time-dependent backgrounds,
for suitable choice of sub-regions in conformal field theories, the temporal
evolution of CHI is entirely causal. We comment on the implications of this
observation and more generally on features of causal constructions and contrast
our results with the behaviour of holographic entanglement entropy. Along the
way we also derive the rate of early time growth and late time saturation (to
the thermal value) of both CHI and entanglement entropy in these backgrounds.


title: The black M2-M5 ring intersection spins

abstract:
  We review the blackfold description of the fully localized orthogonal M2-M5
intersection in eleven-dimensional supergravity which constitutes the direct
gravitational analogue of the Howe-Lambert-West self-dual string soliton
solution. We emphasize the preliminary implications of this description for the
physics of the M2-M5 system and the novel research directions that it opens.
This report contains several new results. As an extension of previous work we
report new results on deformations of the M2-M5-KKW intersection that describe
self-dual ring intersections. Extremal non-supersymmetric configurations of
this type probe novel aspects of the M2-M5 system and allow us to explore
further the merits and limitations of the blackfold description of black brane
intersections. In particular, we provide an example of a situation where an
effective description of extremal non-supersymmetric spike configurations is
shown to capture correctly features of the exact solutions beyond its strict
regime of validity. This observation hints at the existence of improved
convergence properties in the underlying derivative expansion scheme without
the necessary presence of supersymmetry.


title: Flat bands with local Berry curvature in multilayer graphene

abstract:
  We demonstrate that flat bands with local Berry curvature arise naturally in
chiral (ABC) multilayer graphene placed on a boron nitride (BN) substrate. The
degree of flatness can be tuned by varying the number of graphene layers N. For
N = 7 the bands become nearly flat, with a small bandwidth of 3.6 meV. The two
nearly flat bands coming from the K and K' valleys cross along lines in the
reduced zone. Weak intervalley tunneling turns the bandcrossing into an avoided
crossing, producing two nearly flat bands with global Chern number zero, but
with local Berry curvature. The flatness of the bands suggests that many body
effects will dominate the physics, while the local Berry curvature of the bands
endows the system with a nontrivial quantum geometry. The quantum geometry
effects manifest themselves through the quantum distance (Fubini-Study) metric,
rather than the more conventional Chern number. Multilayer graphene on BN thus
provides a platform for investigating the effect of interactions in a system
with a non-trivial quantum distance metric, without the complication of
non-zero Chern numbers. We note in passing that flat bands with non-zero Chern
number can also be realized by making use of magnetic adatoms, and explicitly
breaking time reversal symmetry.


title: Single magnetic impurities in the Kane-Mele model

abstract:
  The realization of the spin-Hall effect in quantum wells has led to a
plethora of studies regarding the properties of the edge states of a 2D
topological insulator. These edge states constitute a class of one-dimensional
liquids, called the helical liquid, where an electron's spin quantization axis
is tied to its momentum. In contrast to one dimensional conductors, magnetic
impurities - below the Kondo temperature - cannot block transport and one
expects the current to circumvent the impurity. To study this phenomenon, we
consider the single impurity Anderson model embedded into an edge of a
Kane-Mele ribbon with up to 512x80 sites and use the numerically exact
continuous time QMC method to study the Kondo effect. We present results on the
temperature dependence of the spectral properties of the impurity and the bulk
system that show the behaviour of the system in the various regimes of the
Anderson model. A view complementary to the single particle spectral functions
can be obtained using the spatial behaviour of the spin-spin correlation
functions. Here we show the characteristic, algebraic decay in the edge channel
near the impurity.


title:
On using angular cross-correlations to determine source redshift
  distributions

abstract:
  We investigate how well the redshift distribution of a population of
extragalactic objects can be reconstructed using angular cross-correlations
with a sample whose redshifts are known. We derive the minimum variance
quadratic estimator, which has simple analytic representations in very
applicable limits and is significantly more sensitive than earlier proposed
estimation procedures. This estimator is straightforward to apply to
observations, it robustly finds the likelihood maximum, and it conveniently
selects angular scales at which fluctuations are well approximated as
independent between redshift bins and at which linear theory applies. We find
that the linear bias times number of objects in a redshift bin generally can be
constrained with cross-correlations to fractional error (10^2 n/N)^1/2, where N
is the total number of spectra per dz and n is the number of redshift bins
spanned by the bulk of the unknown population. The error is often independent
of the sky area and sampling fraction. Furthermore, we find that sub-percent
measurements of the angular source density per unit redshift, dN/dz, are in
principle possible, although cosmic magnification needs to be accounted for at
fractional errors of <~ 10 per cent. We discuss how the sensitivity to dN/dz
changes as a function of photometric and spectroscopic depth and how to
optimize the survey strategy to constrain dN/dz. We also quantify how well
cross-correlations of photometric redshift bins can be used to self-calibrate a
photometric redshift sample. Simple formulae that can be quickly applied to
gauge the utility of cross correlating different samples are given.


title:
Asteroseismic classification of stellar populations among 13000 red
  giants observed by Kepler

abstract:
  Of the more than 150000 targets followed by the Kepler Mission, about 10%
were selected as red giants. Due to their high scientific value, in particular
for Galaxy population studies and stellar structure and evolution, their Kepler
light curves were made public in late 2011. More than 13000 (over 85%) of these
stars show intrinsic flux variability caused by solar-like oscillations making
them ideal for large scale asteroseismic investigations. We automatically
extracted individual frequencies and measured the period spacings of the dipole
modes in nearly every red giant. These measurements naturally classify the
stars into various populations, such as the red giant branch, the low-mass
(M/Msol < 1.8) helium-core-burning red clump, and the higher-mass (M/Msol >
1.8) secondary clump. The period spacings also reveal that a large fraction of
the stars show rotationally induced frequency splittings. This sample of stars
will undoubtedly provide an extremely valuable source for studying the stellar
population in the direction of the Kepler field, in particular when combined
with complementary spectroscopic surveys.


title:
Quantum quench in matrix models: Dynamical phase transitions, Selective
  equilibration and the Generalized Gibbs Ensemble

abstract:
  Quantum quench dynamics is considered in a one dimensional unitary matrix
model with a single trace potential. This model is integrable and has been
studied in the context of non-critical string theory. We find dynamical phase
transitions, and study the role of the quantum critical point. In course of the
time evolutions, we find evidence of selective equilibration for a certain
class of observables. The equilibrium is governed by the Generalized Gibbs
Ensemble (GGE) and differs from the standard Gibbs ensemble. We compute the
production of entropy which is O(N) for large N matrices. An important feature
of the equilibration is the appearance of an energy cascade, reminiscent of the
Richardson cascade in turbulence, where we find flow of energy from initial
long wavelength modes to progressively shorter wavelength excitations. We
discuss possible implication of the equilibration and of GGE in string theories
and higher spin theories. In another related study, we compute time evolutions
in a double trace unitary matrix model, which arises as an effective theory of
D2 branes in IIA string theory in the confinement phase. We find similar
equilibrations and dynamical transitions in this matrix model. The dynamical
transitions are related to Gregory-Laflamme transitions in string theory and
are potentially connected with the issue of appearance of naked singularities.


title: Incompatibility of the tunneling limit with laser fields

abstract:
  The Schwinger limit refers to longitudinal electric fields that are
sufficiently strong to "polarize the vacuum" into electron-positron pairs by a
tunneling mechanism. Laser fields are transverse electromagnetic fields for
which the Schwinger limit has no relevance. Longitudinal and transverse fields
are fundamentally different because of the different values of the
F^{{\mu}{\nu}}F_{{\mu}{\nu}} Lorentz invariant that characterizes the fields.
One aspect of this difference is the zero-frequency limit, that exists for
longitudinal fields, but is ill-defined for transverse fields. The goal of
approaching the Schwinger limit with sufficiently strong lasers is thus not a
possibility. Tunneling transition rates are characterized by an exponential
behavior of the form exp(-C/E), where E is the magnitude of the applied
electric field and C is a system-dependent constant. Searches for such behavior
within a Coulomb-gauge treatment of laser-induced processes are shown to fail.


title:
Models with three Higgs doublets in the triplet representations of A4 or
  S4

abstract:
  We consider the quark sector of theories containing three scalar SU(2)_L
doublets in the triplet representation of A4 (or of S4) and three generations
of quarks in arbitrary A4 (or S4) representations. We show that, for all
possible choices of quark field representations and for all possible alignments
of the Higgs vacuum expectation values that can constitute global minima of the
scalar potential, it is not possible to obtain simultaneously non-vanishing
quark masses and a non-vanishing CP-violating phase in the CKM quark mixing
matrix. As a result, in this minimal form, models with three scalar fields in
the triplet representation of A4 or of S4 cannot be extended to the quark
sector in a way consistent with experiment.


title: The Critical Importance of Russell's Diagram

abstract:
  The idea of dwarf and giants stars, but not the nomenclature, was first
established by Eijnar Hertzsprung in 1905; his first diagrams in support
appeared in 1911. In 1913 Henry Norris Russell could demonstrate the effect far
more strikingly because he measured the parallaxes of many stars at Cambridge,
and could plot absolute magnitude against spectral type for many points. The
general concept of dwarf and giant stars was essential in the galactic
structure work of Harlow Shapley, Russell's first graduate student. In order to
calibrate the period-luminosity relation of Cepheid variables, he was obliged
to fall back on statistical parallax using only 11 Cepheids, a very sparse
sample. Here the insight provided by the Russell diagram became critical. The
presence of yellow K giant stars in globular clusters credentialed his
calibration of the period-luminosity relation by showing that the calibrated
luminosity of the Cepheids was comparable to the luminosity of the K giants. It
is well known that in 1920 Shapley did not believe in the cosmological
distances of Heber Curtis' spiral nebulae. It is not so well known that in 1920
Curtis' plot of the period-luminosity relation suggests that he didn't believe
it was a physical relation and also he failed to appreciate the significance of
the Russell diagram for understanding the large size of the Milky Way.


title:
The Distance to the Massive Galactic Cluster Westerlund 2 from a
  Spectroscopic and HST Photometric Study

abstract:
  We present a spectroscopic and photometric determination of the distance to
the young Galactic open cluster Westerlund 2 using WFPC2 imaging from the
Hubble Space Telescope and ground-based optical spectroscopy. HST imaging in
the F336W, F439W, F555W, and F814W filters resolved many sources previously
undetected in ground-based observations and yielded photometry for 1136 stars.
We identified fifteen new O-type stars, along with two probable binary systems,
including MSP 188 (O3 + O5.5). We fit reddened SEDs based on the Padova
isochrones to the photometric data to determine individual reddening parameters
$R_{V}$ and $A_{V}$ for O-type stars in Wd2. We find average values $\langle
R_{V} \rangle = 3.77 \pm 0.09$ and $\langle A_{V} \rangle = 6.51 \pm 0.38$ mag,
which result in a smaller distance than most other spectroscopic and
photometric studies. After a statistical distance correction accounting for
close unresolved binaries (factor of 1.08), our spectroscopic and photometric
data on 29 O-type stars yield that Westerlund 2 has a distance $\langle d
\rangle = 4.16 \pm 0.07$ (random) $+0.26$ (systematic) kpc. The cluster's age
remains poorly constrained, with an upper limit of 3 Myr. Finally, we report
evidence of a faint mid-IR PAH ring surrounding the well-known binary candidate
MSP~18, which appears to lie at the center of a secondary stellar grouping
within Westerlund 2.


title: Potential theory, path integrals and the Laplacian of the indicator

abstract:
  This paper links the field of potential theory -- i.e. the Dirichlet and
Neumann problems for the heat and Laplace equation -- to that of the Feynman
path integral, by postulating that the potential is equal to plus/minus the
Laplacian of the indicator of the domain D. The Laplacian of the indicator is a
generalized function: it is the d-dimensional analogue of the Dirac
delta'-function. This function has -- according to the author's best knowledge
-- not formally been defined before.
  We show, first, that the path integral's perturbation series (or Born series)
matches the classical single and double boundary layer series of potential
theory, thereby connecting two hitherto unrelated fields. Second, we show that
the perturbation series is valid for all domains D that allow Green's theorem
(i.e. with a finite number of corners, edges and cusps), thereby expanding the
classical applicability of boundary layers. Third, we show that the minus
(plus) in the potential holds for the Dirichlet (Neumann) boundary condition;
showing for the first time a particularly close connection between these two
classical problems. Fourth, we demonstrate that the perturbation series of the
path integral converges in a monotone/alternating fashion, depending on the
convexity/concavity of the domain.
  We also discuss the third boundary problem (which poses Robin boundary
conditions) and discuss an extension to moving domains.


title: Antipode and Primitive elements in the Hopf Monoid of Super Characters

abstract:
  From a recent paper, we recall the Hopf monoid structure on the
supercharacters of the unipotent uppertriangular groups over a finite field. We
give cancelation free formula for the antipode applied to the bases of class
functions and power sum functions, giving new cancelation free formulae for the
standard Hopf algebra of supercharacters and symmetric functions in
noncommuting variables. We also give partial results for the antipode on the
supercharacter basis, and explicitly describe the primitives of this Hopf
monoid.


title: Decoupling Limits of sGoldstino Modes in Global and Local Supersymmetry

abstract:
  We study the decoupling limit of a superheavy sgoldstino field in
spontaneously broken N=1 supergravity. Our approach is based on K\"ahler
superspace, which, among others, allows direct formulation of N=1 supergravity
in the Einstein frame and correct identifications of mass parameters. Allowing
for a non-renormalizable K\"ahler potential in the hidden sector, the
decoupling limit of a superheavy sgoldstino is identified with an infinite
negative K\"ahler curvature. Constraints that lead to non-linear realizations
of supersymmetry emerge as consequence of the equations of motion of the
goldstino superfield when considering the decoupling limit. Finally, by
employing superspace Bianchi identities, we identify the real chiral
superfield, which will be the superconformal symmetry breaking chiral
superfield that enters the conservation of the Ferrra-Zumino multiplet in the
field theory limit of N=1 supergravity.


title: Quantum-enhanced micro-mechanical displacement sensitivity

abstract:
  We report on a hitherto unexplored application of squeezed light: for
quantum-enhancement of mechanical transduction sensitivity in microcavity
optomechanics. Using a toroidal silica microcavity, we experimentally
demonstrate measurement of the transduced phase modulation signal with a
sensitivity $-0.72(\pm 0.01)$\,dB below the shot noise level. This is achieved
for resonant probing in the highly under-coupled regime, by preparing the probe
in a weak coherent state with phase squeezed vacuum states at sideband
frequencies.


title: Beta Functions of Topologically Massive Supergravity

abstract:
  We compute the one-loop beta functions of the cosmological constant, Newton's
constant and the topological mass in topologically massive supergravity in
three dimensions. We use a variant of the proper time method supplemented by a
simple choice of cutoff function. We find that the dimensionless coefficient of
the Chern-Simons term, $\nu$, has vanishing beta function. The flow of the
cosmological constant and Newton's constant depends on $\nu$; we study
analytically the structure of the flow and its fixed points in the limits of
small and large $\nu$.


title: The Neutron Star Zoo

abstract:
  Neutron stars are a very diverse population, both in their observational and
their physical properties. They prefer to radiate most of their energy at X-ray
and gamma-ray wavelengths. But whether their emission is powered by rotation,
accretion, heat, magnetic fields or nuclear reactions, they are all different
species of the same animal whose magnetic field evolution and interior
composition remain a mystery. This article will broadly review the properties
of inhabitants of the neutron star zoo, with emphasis on their high-energy
emission.


title: Centrality-constrained graph embedding

abstract:
  Visual rendering of graphs is a key task in the mapping of complex network
data. Although most graph drawing algorithms emphasize aesthetic appeal,
certain applications such as travel-time maps place more importance on
visualization of structural network properties. The present paper advocates a
graph embedding approach with centrality considerations to comply with node
hierarchy. The problem is formulated as one of constrained multi-dimensional
scaling (MDS), and it is solved via block coordinate descent iterations with
successive approximations and guaranteed convergence to a KKT point. In
addition, a regularization term enforcing graph smoothness is incorporated with
the goal of reducing edge crossings. Experimental results demonstrate that the
algorithm converges, and can be used to efficiently embed large graphs on the
order of thousands of nodes.


title: A vanishing theorem and symbolic powers of planar point ideals

abstract:
  The purpose of this note is twofold. We present first a vanishing theorem for
families of linear series with base ideal being a fat points ideal. We apply
then this result in order to give a partial proof of a conjecture raised by
Bocci, Harbourne and Huneke concerning containment relations between ordinary
and symbolic powers of planar point ideals.


title: Asymptotic estimates on the Erd\H{o}s-Straus conjecture

abstract:
  In this paper analyzes \textit{The Erd\H{o}s-Straus conjecture} asserts that
$f$$(n)$ $>$ 0 for every $n$ $\geq$ 2, where $f(n)$ indicates the number of
solutions to the Diophantine Equation
$\frac{4}{n}=\frac{1}{n_1}+\frac{1}{n_2}+\frac{1}{n_3}$. We show that there
exists a function $G(p)$ to be a boundary asymptotic of
$\sum_{p\leq{N}}f_{I}(p)$, which will have an associated error. We analyze the
case when n is a prime number, this was separately developed by Terence Tao [8]
and Jia [1], [2].


title:
The evolution of the luminosity-temperature-mass relations of hot gas in
  Chandra clusters at 0.4 < z < 1.4

abstract:
  We analyzed the luminosity-temperature-mass of gas (L_{X} - T - M_{g})
relation for sample of galaxy clusters that have been observed by the Chandra
satellite. We used 21 high-redshift clusters (0.4 < z < 1.4).
  We assumed a power-law relation between the X-ray luminosity of galaxy
clusters and its temperature and redshift L_{X} ~
(1+z)^{A_{L_{X}T}}T^{beta_{L_{X}T}}. We obtained that for an Omega_{m} = 0.27
and Lambda = 0.73 universe, A_{L_{X}T} = 1.50 +/- 0.23, beta_{L_{X}T} = 2.55
+/- 0.07 (for 68% confidence level).
  Then, we found the evolution of M_{g} - T relation is small. We assumed a
power-law relation in the form M_{g} ~ (1+z)^{A_{M_{g}T}}T^{beta_{M_{g}T}}
also, and we obtained A_{M_{g}T} = -0.58 +/- 0.13 and beta_{M_{g}T} = 1.77 +/-
0.16. We also obtained the evolution in M_{g} - L_{X} relation, we can conclude
that such relation has strong evolution for our cosmological parameters. We
used M_{g} ~ (1+z)^{A_{M_{g}L_{X}}}L^{beta_{M_{g}L_{X}}} equation for assuming
this relation and we found A_{M_{g}L_{X}} ~ -1.86 +/- 0.34 and
beta_{M_{g}L_{X}} = 0.73 +/- 0.15 for Omega_{m} = 0.27 and Lambda = 0.73
universe.
  In overal, the clusters on big redshifts have much stronger evolution between
correlations of luminosity, temperature and mass, then such correlations for
clusters at small redshifts. We can conclude that such strong evolution in
L_{X} - T - M_{g} correlations indicate that in the past the clusters have
bigger temperature and higher luminosity.


title: Neutral Meson Decays into Two Photons from Lattice QCD

abstract:
  A precision determination of the neutral-pion width would improve
determinations of the splitting between the up- and down-quark masses, and
matrix elements for the decay of neutral mesons into two photons could play a
role in the attempt to probe beyond-the-Standard Model physics in muon $g-2$
experiments. The theoretical error is dominated by hadronic light-by-light
diagrams, and since direct measurements are extremely difficult, model
calculations factorize it into two-photon diagrams connected by the lightest
hadrons. We employ perturbative techniques to express the photon as a
superposition of QCD eigenstates accessible in lattice-QCD calculations and
found that vector-meson dominance is a poor description of the two-photon decay
process when both photons are off shell.


title:
The internal structure of neutron stars and white dwarfs, and the Jacobi
  virial equation. II

abstract:
  In a previous paper we have shown that the function \Gamma(M,
EOS)=\alpha\beta_{GR}/\Lambda^{0.9}(R) is constant (~ 0.4) for pre
main-sequence stars (PMS), white dwarfs (WD) and for some neutron star (NS)
models, where \alpha_{GR} and \beta_{GR} are the form-factors of the
gravitational potential energy and of the moment of inertia. To investigate the
structural evolution of another type of celestial bodies, we use the MESA code
to extend these calculations to gaseous planets. We show that this function is
conserved for all models during the whole planetary evolution and is
independent of the planet mass. We also analyse the cases for which this
function is not conserved during some stellar evolutionary phases. For the PMS
to the WD cooling sequences, we have found a connection between the strong
variations of \Gamma(M, EOS) during the intermediary evolutionary phases and
the specific nuclear power. A threshold for the specific nuclear power was
determined. Below this limit this function is invariant (~ 0.4) for these
models, i.e., at the initial and final stages (PMS and WD). Concerning NS, we
study the influence of the equation of state (EOS) on this function and refine
the exponent of the auxiliary function \Lambda(R) to be ~ 0.8. It is shown that
the function \Gamma(M, EOS) is also invariant (~ 0.4) and is independent of the
EOS and of the stellar mass. Therefore, we confirm that regardless of the final
products of the stellar evolution, NS or WD, they recover the initial value of
\Gamma(M, EOS) ~ 0.4 acquired at the PMS. Finally, we have introduced a
macroscopic stability "criterion" for neutron star models based on the
properties of the relativistic product \alpha\beta_{GR}.


title:
The Effects of Polarized Foregrounds on 21cm Epoch of Reionization Power
  Spectrum Measurements

abstract:
  Experiments aimed at detecting highly-redshifted 21 centimeter emission from
the Epoch of Reionization (EoR) are plagued by the contamination of foreground
emission. A potentially important source of contaminating foregrounds may be
Faraday-rotated, polarized emission, which leaks into the estimate of the
intrinsically unpolarized EoR signal. While these foregrounds' intrinsic
polarization may not be problematic, the spectral structure introduced by the
Faraday rotation could be. To better understand and characterize these effects,
we present a simulation of the polarized sky between 120 and 180 MHz. We
compute a single visibility, and estimate the three-dimensional power spectrum
from that visibility using the delay spectrum approach presented in Parsons et
al. (2012b) . Using the Donald C. Backer Precision Array to Probe the Epoch of
Reionization (PAPER) as an example instrument, we show the expected leakage
into the unpolarized power spectrum to be several orders of magnitude above the
expected 21cm EoR signal.


title: Well-rounded equivariant deformation retracts of Teichm\"uller spaces

abstract:
  In this paper, we construct spines, i.e., $\Mod_g$-equivariant deformation
retracts, of the Teichm\"uller space $\T_g$ of compact Riemann surfaces of
genus $g$. Specifically, we define a $\Mod_g$-stable subspace $S$ of positive
codimension and construct an intrinsic $\Mod_g$-equivariant deformation
retraction from $\T_g$ to $S$. As an essential part of the proof, we construct
a canonical $\Mod_g$-deformation retraction of the Teichm\"uller space $\T_g$
to its thick part $\T_g(\varepsilon)$ when $\varepsilon$ is sufficiently small.
These equivariant deformation retracts of $\T_g$ give cocompact models of the
universal space $\underline{E}\Mod_g$ for proper actions of the mapping class
group $\Mod_g$. These deformation retractions of $\T_g$ are motivated by the
well-rounded deformation retraction of the space of lattices in $\R^n$. We also
include a summary of results and difficulties of an unpublished paper of
Thurston on a potential spine of the Teichm\"uller space.


title: Ultra-compact binaries: relevance and role of Utrecht

abstract:
  We present a short overview of the formation and evolution of ultra-compact
binaries. They are relevant to a surprisingly large number of astrophysical
phenomena (binary interactions, mass transfer stability, explosive phenomena
such as type Ia supernovae and gravitational waves).


title:
Detection of a magnetic field in three old and inactive solar-like
  planet-hosting stars

abstract:
  Our understanding of magnetic fields in late-type stars is strongly driven by
what we know of the solar magnetic field. For this reason, it is crucial to
understand how typical the solar dynamo is. To do this we need to compare the
solar magnetic field with that of other stars as similar to the Sun as
possible, both in stellar parameters and age, hence activity. We present here
the detection of a magnetic field in three planet-hosting solar-like stars
having a mass, age, and activity level comparable to that of the Sun. We used
the HARPSpol spectropolarimeter to obtain high-resolution high-quality
circularly polarised spectra of HD 70642, HD 117207, and HD 154088, using the
Least-Squares Deconvolution technique to detect the magnetic field. From the
Stokes I spectra, we calculated the logR activity index for each star. We
compared the position of the stars in the Hertzsprung-Russell diagram to
evolutionary tracks, to estimate their mass and age. We used the lithium
abundance, derived from the Stokes I spectra, to further constrain the ages. We
obtained a definite magnetic field detection for both HD 70642 and HD 154088,
while for HD 117207 we obtained a marginal detection. Due to the lower
signal-to-noise ratio of the observations, we were unable to detect the
magnetic field in the second set of observations available for HD 117207 and HD
154088. On the basis of effective temperature, mass, age, and activity level
the three stars can be considered solar analogs. HD 70642, HD 117207, and HD
154088 are ideal targets for a comparative study between the solar magnetic
field and that of solar analogs.


title: Formal Fourier Jacobi Expansions and Special Cycles of Codimension 2

abstract:
  We prove that formal Fourier Jacobi expansions of degree 2 are Siegel modular
forms. As a corollary, we deduce modularity of the generating function of
special cycles of codimension 2, which were defined by Kudla. A second
application is the proof of termination of an algorithm to compute Fourier
expansions of arbitrary Siegel modular forms of degree 2. Combining both
results enables us to compute relations of special cycles in the second Chow
group.


title:
Using $\D$-operators to construct orthogonal polynomials satisfying
  higher order difference or differential equations

abstract:
  We introduce the concept of $\D$-operators associated to a sequence of
polynomials $(p_n)_n$ and an algebra $\A$ of operators acting in the linear
space of polynomials. In this paper, we show that this concept is a powerful
tool to generate families of orthogonal polynomials which are eigenfunctions of
a higher order difference or differential operator. Indeed, given a classical
discrete family $(p_n)_n$ of orthogonal polynomials (Charlier, Meixner,
Krawtchouk or Hahn), we form a new sequence of polynomials $(q_n)_n$ by
considering a linear combination of two consecutive $p_n$:
$q_n=p_n+\beta_np_{n-1}$, $\beta_n\in \RR$. Using the concept of $\D$-operator,
we determine the structure of the sequence $(\beta_n)_n$ in order that the
polynomials $(q_n)_n$ are common eigenfunctions of a higher order difference
operator. In addition, we generate sequences $(\beta_n)_n$ for which the
polynomials $(q_n)_n$ are also orthogonal with respect to a measure. The same
approach is applied to the classical families of Laguerre and Jacobi
polynomials.


title: Measurement of a qubit and measurement with a qubit

abstract:
  Generally, the measurement process consists in coupling a system to a
detector that can give a continuous output. However, it may be interesting to
use as a detector a system with a discrete spectrum, especially in view of
applications to quantum information. Here, we study 1) a two-level system
measuring another two-level system (qubit); 2) a generic system measuring a
qubit; 3) a qubit measuring a generic system. The results include the case when
a postselection on the measured system is made. We provide the exact solution,
and also a controlled expansion in the coupling parameter, giving formulas
valid in the weak measurement regime for arbitrary preparation and
postselection. The concept of generalized Wigner functions is introduced.


title: Spatially adaptive post-processing of ensemble forecasts for temperature

abstract:
  We propose an extension of the non-homogeneous Gaussian regression (NGR)
model by Gneiting et al. (2005) that yields locally calibrated probabilistic
forecasts of tem- perature, based on the output of an ensemble prediction
system (EPS). Our method represents the mean of the predictive distributions as
a sum of short-term averages of local temperatures and EPS-driven terms. For
the spatial interpolation of temperature averages and local forecast
uncertainty parameters we use a Gaussian random field model with an
intrinsically stationary component that captures large scale fluctuations and a
location-dependent nugget effect that accounts for small scale variability.
Based on the dynamical forecasts by the COSMO-DE-EPS and observational data
over Germany we evaluate the performance of our method and and compare it with
other post-processing approaches such as geostatistical model averaging. Our
method yields locally calibrated and sharp probabilistic forecasts and compares
favorably with other approaches. It is reasonably simple, computationally
efficient, and therefore suitable for operational usage in the post-processing
of temperature ensemble forecasts.


title: Scale invariance vs conformal invariance

abstract:
  In this review article, we discuss the distinction and possible equivalence
between scale invariance and conformal invariance in relativistic quantum field
theories. Under some technical assumptions, we can prove that scale invariant
quantum field theories in $d=2$ dimension necessarily possess the enhanced
conformal symmetry. The use of the conformal symmetry is well appreciated in
the literature, but the fact that all the scale invariant phenomena in $d=2$
dimension enjoy the conformal property relies on the deep structure of the
renormalization group. The outstanding question is whether this feature is
specific to $d=2$ dimension or it holds in higher dimensions, too. As of
January 2014, our consensus is that there is no known example of scale
invariant but non-conformal field theories in $d=4$ dimension under the
assumptions of (1) unitarity, (2) Poincar\'e invariance (causality), (3)
discrete spectrum in scaling dimension, (4) existence of scale current and (5)
unbroken scale invariance in the vacuum. We have a perturbative proof of the
enhancement of conformal invariance from scale invariance based on the higher
dimensional analogue of Zamolodchikov's $c$-theorem, but the non-perturbative
proof is yet to come. As a reference we have tried to collect as many
interesting examples of scale invariance in relativistic quantum field theories
as possible in this article. We give a complementary holographic argument based
on the energy-condition of the gravitational system and the space-time
diffeomorphism in order to support the claim of the symmetry enhancement. We
believe that the possible enhancement of conformal invariance from scale
invariance reveals the sublime nature of the renormalization group and
space-time with holography.


title:
Monitoring and Optimization for Power Grids: A Signal Processing
  Perspective

abstract:
  The smart grid vision is to revitalize the electric power network by
leveraging the proven sensing, communication, control, and machine learning
technologies to address pressing issues related to security, stability,
environmental impact, market diversity, and novel power technologies.
Significant effort and investment have been committed to architect the
necessary infrastructure by installing advanced metering systems and
establishing data communication networks throughout the grid. Signal processing
methodologies are expected to play a major role in this context by providing
intelligent algorithms that fully exploit such pervasive sensing and control
capabilities to realize the vision and manifold anticipated benefits of the
smart grid. In this feature article, analytical background and relevance of
signal processing tools to power systems are delineated, while introducing
major challenges and opportunities for the future grid engineering. From grid
informatics to inference for monitoring and optimization tools, energy-related
issues are shown to offer a fertile ground for signal processing growth whose
time has come.


title: Optical control of resonant Auger processes

abstract:
  We theoretically show that core-excited state populations can be efficiently
manipulated with strong optical fields during their decay, which takes place in
a few femtoseconds. We focus on the $1s^{-1}3p$ resonant excitation in neon,
where the $1s^{-1}3p$ and $1s^{-1}3s$ core-excited states are coupled by an
optical field. By analyzing the Auger electron spectrum we observe the
inner-shell population transfer induced by the optical coupling. We also show
that the angular anisotropy of the Auger electron is imprinted in the multipeak
structure induced by the optical-dressed continuum, namely sidebands.


title:
Co-evolution of networks and quantum dynamics: a generalization of
  preferential attachment

abstract:
  We propose a model of network growth in which the network is co-evolving
together with the dynamics of a quantum mechanical system, namely a quantum
walk taking place over the network. The model naturally generalizes the
Barab\'{a}si-Albert model of preferential attachment and has a rich set of
tunable parameters, such as the initial conditions of the dynamics or the
interaction of the system with its environment. We show that the model produces
networks with two-modal power-law degree distributions, super-hubs, finite
clustering coefficient, small-world behaviour and non-trivial degree-degree
correlations.


title: Large deviations for random walks in a random environment on a strip

abstract:
  We consider a random walk in a random environment (RWRE) on the strip of
finite width $\mathbb{Z} \times \{1,2,\ldots,d\}$. We prove both quenched and
averaged large deviation principles for the position and the hitting times of
the RWRE. Moreover, we prove a variational formula that relates the quenched
and averaged rate functions, thus extending a result of Comets, Gantert, and
Zeitouni for nearest-neighbor RWRE on $\mathbb{Z}$


title: The LOFAR View of Cosmic Magnetism

abstract:
  The origin of magnetic fields in the Universe is an open problem in
astrophysics and fundamental physics. Polarization observations with the
forthcoming large radio telescopes will open a new era in the observation of
magnetic fields and should help to understand their origin. At low frequencies,
LOFAR (10-240 MHz) will allow us to map the structure of weak magnetic fields
in the outer regions and halos of galaxies, in galaxy clusters and in the Milky
Way via their synchrotron emission. Even weaker magnetic fields can be measured
at low frequencies with help of Faraday rotation measures. A detailed view of
the magnetic fields in the local Milky Way will be derived by Faraday rotation
measures from pulsars. First promising images with LOFAR have been obtained for
the Crab pulsar-wind nebula, the spiral galaxy M51, the radio galaxy M87 and
the galaxy clusters A2255 and A2256. With help of the polarimetric technique of
"Rotation Measure Synthesis", diffuse polarized emission has been detected from
a magnetic bubble in the local Milky Way. Polarized emission and rotation
measures were measured for more than 20 pulsars so far.


title: Local Log-linear Models for Capture-Recapture

abstract:
  Log-linear models are often used to estimate the size of a closed population
using capture-recapture data. When capture probabilities are related to
auxiliary covariates, one may select a separate model based on each of several
post-strata. We extend post-stratification to its logical extreme by selecting
a local log-linear model for each observed unit, while smoothing to achieve
stability. Our local models serve a dual purpose: In addition to estimating the
size of the population, we estimate the rate of missingness as a function of
covariates. A simulation demonstrates the superiority of our method when the
generating model varies over the covariate space. Data from the Breeding Bird
Survey is used to illustrate the method.


title:
Large-Scale Fading Behavior for a Cellular Network with Uniform Spatial
  Distribution

abstract:
  Large-scale fading (LSF) between interacting nodes is a fundamental element
in radio communications, responsible for weakening the propagation, and thus
worsening the service quality. Given the importance of channel-losses in
general, and the inevitability of random spatial geometry in real-life wireless
networks, it was then natural to merge these two paradigms together in order to
obtain an improved stochastical model for the LSF indicator. Therefore, in
exact closed-form notation, we generically derived the LSF distribution between
a prepositioned reference base-station and an arbitrary node for a
multi-cellular random network model. In fact, we provided an explicit and
definitive formulation that considered at once: the lattice profile, the users'
random geometry, the effect of the far-field phenomenon, the path-loss
behavior, and the stochastic impact of channel scatters. The veracity and
accuracy of the theoretical analysis were also confirmed through Monte Carlo
simulations.


title: Search using queries on indistinguishable items

abstract:
  We investigate the problem of determining a set S of k indistinguishable
integers in the range [1,n]. The algorithm is allowed to query an integer $q\in
[1,n]$, and receive a response comparing this integer to an integer randomly
chosen from S. The algorithm has no control over which element of S the query q
is compared to. We show tight bounds for this problem. In particular, we show
that in the natural regime where $k\le n$, the optimal number of queries to
attain $n^{-\Omega(1)}$ error probability is $\Theta(k^3 \log n)$. In the
regime where $k>n$, the optimal number of queries is $\Theta(n^2 k \log n)$.
  Our main technical tools include the use of information theory to derive the
lower bounds, and the application of noisy binary search in the spirit of
Feige, Raghavan, Peleg, and Upfal (1994). In particular, our lower bound
technique is likely to be applicable in other situations that involve search
under uncertainty.


title:
Probabilistic Quantitative Precipitation Forecasting Using Ensemble
  Model Output Statistics

abstract:
  Statistical post-processing of dynamical forecast ensembles is an essential
component of weather forecasting. In this article, we present a post-processing
method that generates full predictive probability distributions for
precipitation accumulations based on ensemble model output statistics (EMOS).
We model precipitation amounts by a generalized extreme value distribution that
is left-censored at zero. This distribution permits modelling precipitation on
the original scale without prior transformation of the data. A closed form
expression for its continuous rank probability score can be derived and permits
computationally efficient model fitting. We discuss an extension of our
approach that incorporates further statistics characterizing the spatial
variability of precipitation amounts in the vicinity of the location of
interest. The proposed EMOS method is applied to daily 18-h forecasts of 6-h
accumulated precipitation over Germany in 2011 using the COSMO-DE ensemble
prediction system operated by the German Meteorological Service. It yields
calibrated and sharp predictive distributions and compares favourably with
extended logistic regression and Bayesian model averaging which are state of
the art approaches for precipitation post-processing. The incorporation of
neighbourhood information further improves predictive performance and turns out
to be a useful strategy to account for displacement errors of the dynamical
forecasts in a probabilistic forecasting framework.


title:
Charged-particle pseudorapidity density and anisotropic flow over a wide
  pseudorapidity range using ALICE at the LHC

abstract:
  The pseudorapidity density and anisotropic flow of charged-particles provide
fundamental information about global variables and correlations in heavy-ion
collisions. The pseudorapidity density is related to the energy available for
particle production while the anisotropic flow is related to collective effects
from interactions between these particles. Extending these measurements to very
forward pseudorapidities yields information about the longitudinal expansion of
the system. The first measurements performed at the LHC over more than 8 units
of pseudorapidity are presented. The longitudinal scaling of the measurements
is analyzed and comparison to models is performed.


title: Exact Sparse Recovery with L0 Projections

abstract:
  Many applications concern sparse signals, for example, detecting anomalies
from the differences between consecutive images taken by surveillance cameras.
This paper focuses on the problem of recovering a K-sparse signal x in N
dimensions. In the mainstream framework of compressed sensing (CS), the vector
x is recovered from M non-adaptive linear measurements y = xS, where S (of size
N x M) is typically a Gaussian (or Gaussian-like) design matrix, through some
optimization procedure such as linear programming (LP).
  In our proposed method, the design matrix S is generated from an
$\alpha$-stable distribution with $\alpha\approx 0$. Our decoding algorithm
mainly requires one linear scan of the coordinates, followed by a few
iterations on a small number of coordinates which are "undetermined" in the
previous iteration. Comparisons with two strong baselines, linear programming
(LP) and orthogonal matching pursuit (OMP), demonstrate that our algorithm can
be significantly faster in decoding speed and more accurate in recovery
quality, for the task of exact spare recovery. Our procedure is robust against
measurement noise. Even when there are no sufficient measurements, our
algorithm can still reliably recover a significant portion of the nonzero
coordinates.
  To provide the intuition for understanding our method, we also analyze the
procedure by assuming an idealistic setting. Interestingly, when K=2, the
"idealized" algorithm achieves exact recovery with merely 3 measurements,
regardless of N. For general K, the required sample size of the "idealized"
algorithm is about 5K.

categories: stat.ML cs.IT cs.LG math.IT math.ST stat.TH


title:
Theory of the lower critical magnetic field for a two-dimensional
  superconducting film in a non-uniform field

abstract:
  We consider the first appearance of vortices in a two-dimensional (2-D)
superconducting film exposed to a non-uniform magnetic field, $\mathbf{B_a}$,
produced by a nearby coil. The film has "infinite" radius, $R_f$, and thickness
$t$ about equal to the coherence length, $\xi$. The coil is approximated as a
point dipole. We find that the first vortex-bearing state to appear has both a
vortex and an antivortex. The Gibbs free energy of this state is lower than the
vortex-free state when the applied perpendicular field, $B_0$, at the origin
exceeds the external critical field: $B_{c1}^0 =
\frac{4\sqrt{2}\Lambda}{R}\frac{\Phi_0}{4\pi
\Lambda^2}ln\left(\frac{\Lambda}{\xi}\right)$, where
$\frac{\Phi_0}{4\pi\Lambda^2}ln\left(\frac{\Lambda}{\xi}\right) \equiv
B_{c1}^{2D}$ is the intrinsic critical field in 2-D, $\Lambda \equiv
2\lambda^2/t$ the 2-D penetration depth introduced by Pearl, and $\lambda$ is
the bulk penetration depth. The prefactor, $4\sqrt{2}\Lambda/R$, is calculated
in the strong-screening regime, $\Lambda/R \ll 1$. $R$ is the radial distance
at which the applied perpendicular field, $B_{a,z}(\rho)$, changes sign. In the
lab, the onset of vortex effects generally occurs at a field much higher than
$B_{c1}^0$, indicating that vortices are inhibited by the vortex-antivortex
unbinding barrier, or by pinning.


title:
Distributed MAC and Rate Adaptation for Ultrasonically Networked
  Implantable Sensors

abstract:
  The use of miniaturized biomedical devices implanted in the human body and
wirelessly internetworked is promising a significant leap forward in medical
treatment of many pervasive diseases. Recognizing the well-understood
limitations of traditional radio-frequency wireless communications in
interconnecting devices within the human body, in this paper we propose for the
first time to develop network protocols for implantable devices based on
ultrasonic transmissions. We start off by assessing the feasibility of using
ultrasonic propagation in human body tissues and by deriving an accurate
channel model for ultrasonic intra-body communications. Then, we propose a new
ultrasonic transmission and multiple access technique, which we refer to as
Ultrasonic WideBand (UsWB). UsWB is based on the idea of transmitting
information bits spread over very short pulses following a time-hopping
pattern. The short impulse duration results in limited reflection and
scattering effects, and its low duty cycle reduces the thermal and mechanical
effects, which are detrimental for human health. We then develop a multiple
access technique with distributed control to enable efficient simultaneous
access by interfering devices based on minimal and localized information
exchange and on measurements at the receiver only. Finally, we demonstrate the
performance of UsWB through a multi-scale simulator that models the proposed
communication system at the acoustic wave level, at the physical (bit) level,
and at the network (packet) level.


title: Chordal Loewner Equation

abstract:
  The aim of this survey paper is to present a complete direct proof of the
well celebrated cornerstone result in Loewner Theory, originally due to Kufarev
et al [Trudy Tomsk. Gos. Univ. Ser. Meh.-Mat. 200 (1968) 142-164. MR0257336 (41
#1987)], stating that the family of the hydrodynamically normalized conformal
self-maps of the upper-half plane onto the complement of a gradually erased
slit satisfies, under a suitable parametrization, the chordal Loewner
differential equation. The proof is based solely on basic theorems of Geometric
Function Theory combined with some elementary topological facts and does not
require any advanced technique.


title: Entanglement Entropy as a Portal to the Physics of Quantum Spin Liquids

abstract:
  Quantum Spin Liquids (QSLs) are phases of interacting spins that do not order
even at the absolute zero temperature, making it impossible to characterize
them by a local order parameter. In this article, we review the unique view
provided by the quantum entanglement on QSLs. We illustrate the crucial role of
Topological Entanglement Entropy in diagnosing the non-local order in QSLs,
using specific examples such as the Chiral Spin Liquid. We also demonstrate the
detection of anyonic quasiparticles and their braiding statistics using quantum
entanglement. In the context of gapless QSLs, we discuss the detection of
emergent fermionic spinons in a bosonic wavefunction, by studying the size
dependence of entanglement entropy.


title:
An Extension of Teleparallelism and the Geometrization of the
  Electromagnetic Field

abstract:
  As is well known, both Weyl and Weitzenb\"ock spacetimes were initially used
as attempts to geometrize the electromagnetic field. In this letter, we prove
that this field can also be regarded as a geometrical quantity in an extended
version of the Weitzenb\"ock spacetime. The new geometry encompasses features
of both Weyl and Weitzenb\"ock spacetimes. In addition, we obtain Einstein's
field equations coupled to the Maxwell energy-momentum tensor from a purely
geometrical action and, to exemplify the advantage of using this new geometry
when dealing with conformal invariance, we construct a model that is equivalent
to a known conformal invariant teleparallel model.


title:
One-dimensional swimmers in viscous fluids: dynamics, controllability,
  and existence of optimal controls

abstract:
  In this paper we study a mathematical model of one-dimensional swimmers
performing a planar motion while fully immersed in a viscous fluid. The
swimmers are assumed to be of small size, and all inertial effects are
neglected. Hydrodynamic interactions are treated in a simplified way, using the
local drag approximation of resistive force theory. We prove existence and
uniqueness of the solution of the equations of motion driven by shape changes
of the swimmer. Moreover, we prove a controllability result showing that given
any pair of initial and final states, there exists a history of shape changes
such that the resulting motion takes the swimmer from the initial to the final
state. We give a constructive proof, based on the composition of elementary
maneuvers (straightening and its inverse, rotation, translation), each of which
represents the solution of an interesting motion planning problem. Finally, we
prove the existence of solutions for the optimal control problem of finding,
among the histories of shape changes taking the swimmer from an initial to a
final state, the one of minimal energetic cost.


title:
Littelmann path model for geometric crystals, Whittaker functions on Lie
  groups and Brownian motion

abstract:
  Generally speaking, this thesis focuses on the interplay between the
representations of Lie groups and probability theory. It subdivides into
essentially three parts.
  In a first rather algebraic part, we construct a path model for geometric
crystals in the sense of Berenstein and Kazhdan, for complex semi-simple Lie
groups. We will mainly describe the algebraic structure, its natural morphisms
and parameterizations. The theory of total positivity will play a particularly
important role.
  Then, we anticipate on the probabilistic part by exhibiting a canonical
measure on geometric crystals. It uses as ingredients the superpotential for
the flag manifold and a measure invariant under the crystal actions. The image
measure under the weight map plays the role of Duistermaat-Heckman measure. Its
Laplace transform defines Whittaker functions, providing an interesting formula
for all Lie groups. Then it appears clearly that Whittaker functions are to
geometric crystals, what characters are to combinatorial crystals. The
Littlewood-Richardson rule is also exposed.
  Finally we present the probabilistic approach that allows to find the
canonical measure. It is based on the fundamental idea that the Wiener measure
will induce the adequate measure on the algebraic structures through the path
model.
  In the last chapter, we show how our geometric model degenerates to the
continuous classical Littelmann path model and thus recover known results. For
example, the canonical measure on a geometric crystal of highest weight
degenerates into a uniform measure on a polytope, and recovers the
parameterizations of continuous crystals.


title: A Review on the Scalar Field/ Bose-Einstein Condensate Dark Matter Model

abstract:
  We review the work done so far aimed at modeling in an alternative way the
dark matter in the Universe: the scalar field/ Bose-Einstein condensate dark
matter (SFDM/BEC) model. We discuss a number of important achievements and
characteristics of the model. We also describe some of our most recent results
and predictions of the model compared to those of the standard model of
$\Lambda$CDM.


title: Holographic charged fluid dual to third order Lovelock gravity

abstract:
  We study the dual fluid on a finite cutoff surface outside the black brane
horizon in the third order Lovelock gravity. Using nonrelativistic
long-wavelength expansion, we obtain the incompressible Navier-Stokes equations
of dual fluid with external force density on the finite cutoff surface. The
viscosity to entropy density ratio $\eta/s$ is independent of cutoff surface
and does not get modification from the third order Lovelock gravity influence.
The obtained ratio agrees with the results obtained by using other methods,
such as the Kubo formula at the AdS boundary and the membrane paradigm at the
horizon in the third order Lovelock gravity. These results can be related by
Wilson renormalization group flow. However the kinematic viscosity receives
correction from the third order Lovelock term. We show that the equivalence
between the isentropic flow of the fluid and the radial component of the
gravitational equation observed in the Einstein and Gauss-Bonnet gravities also
holds in the third order Lovelock gravity. This generalization brings more
understandings of relating the gravity theory to the dual fluid.


title: Dynamical Local Chirality and Chiral Symmetry Breaking

abstract:
  We present some of the reasoning and results substantiating the notion that
spontaneous chiral symmetry breaking (SChSB) in QCD is encoded in local chiral
properties of Dirac eigenmodes. Such association is possible when viewing
chirality as a dynamical effect, measured with respect to the benchmark of
statistically independent left-right components. Following this rationale leads
to describing local chiral behavior by a taylor-made correlation, namely the
recently introduced correlation coefficient of polarization C_A. In this
language, correlated modes (C_A>0) show dynamical preference for local
chirality while anti-correlated modes (C_A<0) favor anti-chirality. Our
conclusion is that SChSB in QCD can be viewed as dominance of low-energy
correlation (chirality) over anti-correlation (anti-chirality) of Dirac sea.
The spectral range of local chirality, chiral polarization scale Lambda_ch, is
a dynamically generated scale in the theory associated with SChSB. One
implication of these findings is briefly discussed.


title: Electrical Conductivity of Hot QCD Matter

abstract:
  We study the electric conductivity of hot QCD matter at various temperatures
T within the off-shell parton-hadron-string dynamics transport approach for
interacting partonic, hadronic or mixed systems in a finite box with periodic
boundary conditions. The response of the strongly interacting system in
equilibrium to an external electric field defines the electric conductivity
sigma_0. We find a sizable temperature dependence of the ratio sigma_0/T well
in line with calculations in a relaxation time approach for Tc<T<2.5Tc. The
ratio drops in the hadronic phase with T, shows a minimum close to Tc, and
becomes approximately constant (~0.3) above ~5Tc. Our findings imply that the
QCD matter even at T=Tc is a much better electric conductor than Cu or Ag (at
room temperature).


title:
Bootstrap Methods for the Empirical Study of Decision-Making and
  Information Flows in Social Systems

abstract:
  We characterize the statistical bootstrap for the estimation of
information-theoretic quantities from data, with particular reference to its
use in the study of large-scale social phenomena. Our methods allow one to
preserve, approximately, the underlying axiomatic relationships of information
theory---in particular, consistency under arbitrary coarse-graining---that
motivate use of these quantities in the first place, while providing
reliability comparable to the state of the art for Bayesian estimators. We show
how information-theoretic quantities allow for rigorous empirical study of the
decision-making capacities of rational agents and the time-asymmetric flows of
information in distributed systems. We provide illustrative examples by
reference to ongoing collaborative work on the semantic structure of the
British Criminal Court system and the conflict dynamics of the contemporary
Afghanistan insurgency.

categories: cs.IT cs.SI math.IT physics.soc-ph stat.ME


title: The Traffic Phases of Road Networks

abstract:
  We study the relation between the average traffic flow and the vehicle
density on road networks that we call 2D-traffic fundamental diagram. We show
that this diagram presents mainly four phases. We analyze different cases.
First, the case of a junction managed with a priority rule is presented, four
traffic phases are identified and described, and a good analytic approximation
of the fundamental diagram is obtained by computing a generalized eigenvalue of
the dynamics of the system. Then, the model is extended to the case of two
junctions, and finally to a regular city. The system still presents mainly four
phases. The role of a critical circuit of non-priority roads appears clearly in
the two junctions case. In Section 4, we use traffic light controls to improve
the traffic diagram. We present the improvements obtained by open-loop, local
feedback, and global feedback strategies. A comparison based on the response
times to reach the stationary regime is also given. Finally, we show the
importance of the design of the junction. It appears that if the junction is
enough large, the traffic is almost not slowed down by the junction.


title:
Detection of E-cyanomethanimine towards Sagittarius B2(N) in the Green
  Bank Telescope PRIMOS Survey

abstract:
  The detection E-cyanomethanimine (E-HNCHCN) towards Sagittarius B2(N) is made
by comparing the publicly available Green Bank Telescope (GBT) PRIMOS survey
spectra (Hollis et al.) to laboratory rotational spectra from a reaction
product screening experiment. The experiment uses broadband molecular
rotational spectroscopy to monitor the reaction products produced in an
electric discharge source using a gas mixture of NH3 and CH3CN. Several
transition frequency coincidences between the reaction product screening
spectra and previously unassigned interstellar rotational transitions in the
PRIMOS survey have been assigned to E cyanomethanimine. A total of 8 molecular
rotational transitions of this molecule between 9 and 50 GHz are observed with
the GBT. E-cyanomethanimine, often called the HCN dimer, is an important
molecule in prebiotic chemistry because it is a chemical intermediate in
proposed synthetic routes of adenine, one of the two purine nucleobases found
in DNA and RNA. New analyses of the rotational spectra of both
E-cyanomethanimine and Z-cyanomethanimine that incorporate previous mm-wave
measurements are also reported.


title:
Onset of flow in a confined colloidal glass under an imposed shear
  stress

abstract:
  A confined colloidal glass, under the imposition of a uniform shear stress,
is investigated using numerical simulations. Both at macro- and microscales,
the consequent dynamics during the onset of flow is studied. When the imposed
stress is gradually decreased, the time scale for the onset of steady flow
diverges, associated with long-lived spatial heterogeneities. Near this
yield-stress regime, persistent creep in the form of shear-banded structures is
observed.


title: Rates of Superluminous Supernovae at z~0.2

abstract:
  We calculate the volumetric rate of superluminous supernovae (SLSNe) based on
5 events discovered with the ROTSE-IIIb telescope. We gather light curves of 19
events from the literature and our own unpublished data and employ crude
k-corrections to constrain the pseudo-absolute magnitude distributions in the
rest frame ROTSE-IIIb (unfiltered) band pass for both the hydrogen poor
(SLSN-I) and hydrogen rich (SLSN-II) populations. We find that the peak
magnitudes of the available SLSN-I are narrowly distributed ($M = -21.7 \pm
0.4$) in our unfiltered band pass and may suggest an even tighter intrinsic
distribution when the effects of dust are considered, although the sample may
be skewed by selection and publication biases. The presence of OII features
near maximum light may uniquely signal a high luminosity event, and we suggest
further observational and theoretical work is warranted to assess the possible
utility of such SN 2005ap-like SLSN-I as distance indicators. Using the
pseudo-absolute magnitude distributions derived from the light curve sample, we
measure the SLSN-I rate to be about (32^{+77}_{-26}) events Gpc^{-3} yr^{-1}
h_{71}^{3} at a weighted redshift of z = 0.17, and the SLSN-II rate to be about
(151^{+151}_{-82}) events Gpc^{-3} yr^{-1} h_{71}^{3} at z = 0.15. Given that
the exact nature and limits of these populations are still unknown, we discuss
how it may be difficult to distinguish these rare SLSNe from other transient
phenomena such as AGN activity and tidal disruption events even when multi-band
photometry, spectroscopy, or even high resolution imaging are available.
Including one spectroscopically peculiar event, we determine a total rate for
SLSN-like events of (199^{+137}_{-86}) events Gpc^{-3} yr^{-1} h_{71}^{3} at z
= 0.16.


title:
A symplectic integrator for the symmetry reduced and regularised planar
  3-body problem with vanishing angular momentum

abstract:
  We construct an explicit reversible symplectic integrator for the planar
3-body problem with zero angular momentum. We start with a Hamiltonian of the
planar 3-body problem that is globally regularised and fully symmetry reduced.
This Hamiltonian is a sum of 10 polynomials each of which can be integrated
exactly, and hence a symplectic integrator is constructed. The performance of
the integrator is examined with three numerical examples: The figure eight, the
pythagorean orbit, and a periodic collision orbit.


title:
Affine Invariant Submanifolds with Completely Degenerate
  Kontsevich-Zorich Spectrum

abstract:
  We prove that if the Lyapunov spectrum of the Kontsevich-Zorich cocycle over
an affine SL$(2,\mathbb{R})$-invariant submanifold is completely degenerate,
i.e. $\lambda_2 = \cdots = \lambda_g = 0$, then the submanifold must be an
arithmetic Teichmueller curve in the moduli space of Abelian differentials over
surfaces of genus three, four, or five. As a corollary, we prove that there are
at most finitely many such Teichmueller curves.


title: Beyond Worst-Case Analysis for Joins with Minesweeper

abstract:
  We describe a new algorithm, Minesweeper, that is able to satisfy stronger
runtime guarantees than previous join algorithms (colloquially, `beyond
worst-case guarantees') for data in indexed search trees. Our first
contribution is developing a framework to measure this stronger notion of
complexity, which we call {\it certificate complexity}, that extends notions of
Barbay et al. and Demaine et al.; a certificate is a set of propositional
formulae that certifies that the output is correct. This notion captures a
natural class of join algorithms. In addition, the certificate allows us to
define a strictly stronger notion of runtime complexity than traditional
worst-case guarantees. Our second contribution is to develop a dichotomy
theorem for the certificate-based notion of complexity. Roughly, we show that
Minesweeper evaluates $\beta$-acyclic queries in time linear in the certificate
plus the output size, while for any $\beta$-cyclic query there is some instance
that takes superlinear time in the certificate (and for which the output is no
larger than the certificate size). We also extend our certificate-complexity
analysis to queries with bounded treewidth and the triangle query.