title:
The Deflagration Stage of Chandrasekhar Mass Models For Type Ia
  Supernovae: I. Early Evolution

abstract:
  We present high-resolution, full-star simulations of the post-ignition phase
of Type Ia supernovae using the compressible hydrodynamics code Castro. Initial
conditions, including the turbulent velocity field and ignition site, are
imported directly from a simulation of the last few hours of presupernova
convection using a low Mach number code, Maestro. Adaptive mesh refinement
allows the initial burning front to be modeled with an effective resolution of
36,864^3 zones (~136 m/zone). The initial rise and expansion of the
deflagration front are tracked until burning reaches the star's edge and the
role of the background turbulence on the flame is investigated. The effect of
artificially moving the ignition location closer to the star's center is
explored. The degree to which turbulence affects the burning front decreases
with increasing ignition radius since the buoyancy force is stronger at larger
radii. Even central ignition --- in the presence of a background convective
flow field --- is rapidly carried off-center as the flame is carried by the
flow field. We compare our results to analytic models for burning thermals, and
find that they reproduce the general trends of the bubble's size and mass, but
underpredict the amount of buoyant acceleration due to simplifying assumptions
of the bubble's properties. Overall, we find that the amount of mass that burns
prior to flame break out is small, consistent with a "gravitationally confined
detonation" occurring at a later epoch, but additional burning will occur
following breakout that may modify this conclusion.


title:
Study of the zero modes of the Faddeev-Popov operator in the maximal
  Abelian gauge

abstract:
  A study of the zero modes of the Faddeev-Popov operator in the maximal
Abelian gauge is presented in the case of the gauge group SU(2) and for
different Euclidean space-time dimensions. Explicit examples of classes of
normalizable zero modes and corresponding gauge field configurations are
constructed by taking into account two boundary conditions, namely: i) the
finite Euclidean Yang-Mills action, ii) the finite Hilbert norm.


title:
A probabilistic and deterministic modular algorithm for computing
  Groebner basis over $\Q$

abstract:
  Modular algorithm are widely used in computer algebra systems (CAS), for
example to compute efficiently the gcd of multivariate polynomials. It is known
to work to compute Groebner basis over $\Q$, but it does not seem to be popular
among CAS implementers. In this paper, I will show how to check a candidate
Groebner basis (obtained by reconstruction of several Groebner basis modulo
distinct prime numbers) with a given error probability, that may be 0 if a
certified Groebner basis is desired. This algorithm is now the default
algorithm used by the Giac/Xcas computer algebra system with competitive
timings, thanks to a trick that can accelerate computing Groebner basis modulo
a prime once the computation has been done modulo another prime.


title:
Interaction-induced quantum phase revivals and evidence for the
  transition to the quantum chaotic regime in 1D atomic Bloch oscillations

abstract:
  We study atomic Bloch oscillations in an ensemble of one-dimensional tilted
superfluids in the Bose-Hubbard regime. For large values of the tilt, we
observe interaction-induced coherent decay and matter-wave quantum phase
revivals of the Bloch oscillating ensemble. We analyze the revival period
dependence on interactions by means of a Feshbach resonance. When reducing the
value of the tilt, we observe the disappearance of the quasi-periodic phase
revival signature towards an irreversible decay of Bloch oscillations,
indicating the transition from regular to quantum chaotic dynamics.


title: A family of monotone quantum relative entropies

abstract:
  We study here the elementary properties of the relative entropy
$\cH(A,B)=\tr[\phi(A)-\phi(B)-\phi'(B)(A-B)]$ for $\phi$ a convex function and
$A,B$ bounded self-adjoint operators. In particular, we prove that this
relative entropy is monotone if and only if $\phi'$ is operator monotone. We
use this to appropriately define $\cH(A,B)$ in infinite dimension.


title: Harmonic vectors and matrix tree theorems

abstract:
  The paper describes an explicit combinatorial formula for a harmonic vector
for the Laplacian of a directed graph with arbitrary edge weights. This result
was motivated by questions from mathematical economics, and the formula plays a
crucial role in forthcoming joint work of the author on the emergence of prices
and money in an exchange economy.
  It turns out that the formula is closely related to well-studied problems in
graph theory, in particular to the so-called matrix tree theorem due to W.
Tutte and independently to R. Bott and J. Mayberry. As a further application of
our considerations, we obtain a short new proof of both the matrix tree theorem
as well as its generalization due to S. Chaiken.


title: Misiurewicz Points for Polynomial Maps and Transversality

abstract:
  The behavior under iteration of the critical points of polynomial maps plays
an essential role in understanding its dynamics. We study the special case
where the forward orbits of the critical points are finite. Thurston's theorem
tells us that fixing a particular critical portrait and degree leads to only
finitely may possible polynomials (up to equivalence) and that, in many cases,
their defining equations intersect transversely. We provide explicit algebraic
formulae for the parameters where the critical points of the unicritical
polynomials and bicritical cubic polynomials have a specified exact period. We
pay particular attention to the parameters where the critical orbits are
strictly preperiodic, called Misiurewicz points. Our main tool is the
generalized dynatomic polynomial. We also study the discriminants of these
polynomials to examine the failure of transversality in positive characteristic
for unicritical polynomials.


title: Black Holes in Higher Dimensions (Black Strings and Black Rings)

abstract:
  The main focus of this session was the presentation of new higher-dimensional
black hole solutions, including black rings, black strings, and multi black
holes, and the study of their properties. Besides new asymptotically flat and
locally asymptotically flat black objects also new black holes with anti-de
Sitter asymptotics were reported. The studies of their properties included the
investigation of their stability, their thermodynamics, their analyticity and
their existence. Furthermore, the geodesics in such higher-dimensional
space-times were investigated.


title:
Analytical solution for a class of network dynamics with mechanical and
  financial applications

abstract:
  We show that for a certain class of dynamics at the nodes the response of a
network of any topology to arbitrary inputs is defined in a simple way by its
response to a monotone input. The nodes may have either a discrete or
continuous set of states and there is no limit on the complexity of the
network. The results provide both an efficient numerical method and the
potential for accurate analytic approximation of the dynamics on such networks.
As illustrative applications, we introduce a quasistatic mechanical model with
objects interacting via frictional forces, and a financial market model with
avalanches and critical behavior that are generated by momentum trading
strategies.

categories: cond-mat.stat-mech cond-mat.dis-nn cs.SI physics.soc-ph q-fin.ST


title:
Emergence of charge density wave domain walls above the superconducting
  dome in TiSe2

abstract:
  Superconductivity (SC) in so-called "unconventional superconductors" is
nearly always found in the vicinity of another ordered state, such as
antiferromagnetism, charge density wave (CDW), or stripe order. This suggests a
fundamental connection between SC and fluctuations in some other order
parameter. To better understand this connection, we used high-pressure x-ray
scattering to directly study the CDW order in the layered dichalcogenide TiSe2,
which was previously shown to exhibit SC when the CDW is suppressed by pressure
[1] or intercalation of Cu atoms [2]. We succeeded in suppressing the CDW fully
to zero temperature, establishing for the first time the existence of a quantum
critical point (QCP) at Pc = 5.1 +/- 0.2 GPa, which is more than 1 GPa beyond
the end of the SC region. Unexpectedly, at P = 3 GPa we observed a reentrant,
weakly first order, incommensurate phase, indicating the presence of a Lifshitz
tricritical point somewhere above the superconducting dome. Our study suggests
that SC in TiSe2 may not be connected to the QCP itself, but to the formation
of CDW domain walls.


title: On the Supersymmetric Completion of $R+R^2$ Gravity and Cosmology

abstract:
  We revisit and clarify the supersymmetric versions of $R+ R^2$ gravity, in
view of the renewed interest to these models in cosmology. We emphasize that
the content of the dual standard supergravity theory in the old minimal
formulation necessarily includes two massive chiral multiplets, that we call
the inflaton and the goldstino. We point out that the presence of these
multiplets is model independent in the old minimal formulation and therefore
any theory that contains a single chiral multiplet fails to be a supersymmetric
generalization of the $R+R^2$ gravity. The supergravity interactions of the two
chiral multiplets are encoded in a superpotential mass term and an arbitrary
Kahler potential for the goldstino multiplet. The implication for cosmology of
the supersymmetric $R+R^2$ gravity is also discussed.


title: Tables of record gaps between prime constellations

abstract:
  We present tables of record (maximal) gaps between densest prime
constellations, or k-tuplets. The tables contain all maximal gaps between prime
k-tuplets up to 10^15, for each k<=7.


title: Data-driven Algorithms for Dimension Reduction in Causal Inference

abstract:
  In observational studies, the causal effect of a treatment may be confounded
with variables that are related to both the treatment and the outcome of
interest. In order to identify a causal effect, such studies often rely on the
unconfoundedness assumption, i.e., that all confounding variables are observed.
The choice of covariates to control for, which is primarily based on subject
matter knowledge, may result in a large covariate vector in the attempt to
ensure that unconfoundedness holds. However, including redundant covariates can
affect bias and efficiency of nonparametric causal effect estimators, e.g., due
to the curse of dimensionality. Data-driven algorithms for the selection of
sufficient covariate subsets are investigated. Under the assumption of
unconfoundedness the algorithms search for minimal subsets of the covariate
vector. Based, e.g., on the framework of sufficient dimension reduction or
kernel smoothing, the algorithms perform a backward elimination procedure
assessing the significance of each covariate. Their performance is evaluated in
simulations and an application using data from the Swedish Childhood Diabetes
Register is also presented.


title: Searching of gapped repeats and subrepetitions in a word

abstract:
  A gapped repeat is a factor of the form $uvu$ where $u$ and $v$ are nonempty
words. The period of the gapped repeat is defined as $|u|+|v|$. The gapped
repeat is maximal if it cannot be extended to the left or to the right by at
least one letter with preserving its period. The gapped repeat is called
$\alpha$-gapped if its period is not greater than $\alpha |v|$. A
$\delta$-subrepetition is a factor which exponent is less than 2 but is not
less than $1+\delta$ (the exponent of the factor is the quotient of the length
and the minimal period of the factor). The $\delta$-subrepetition is maximal if
it cannot be extended to the left or to the right by at least one letter with
preserving its minimal period. We reveal a close relation between maximal
gapped repeats and maximal subrepetitions. Moreover, we show that in a word of
length $n$ the number of maximal $\alpha$-gapped repeats is bounded by
$O(\alpha^2n)$ and the number of maximal $\delta$-subrepetitions is bounded by
$O(n/\delta^2)$. Using the obtained upper bounds, we propose algorithms for
finding all maximal $\alpha$-gapped repeats and all maximal
$\delta$-subrepetitions in a word of length $n$. The algorithm for finding all
maximal $\alpha$-gapped repeats has $O(\alpha^2n)$ time complexity for the case
of constant alphabet size and $O(n\log n + \alpha^2n)$ time complexity for the
general case. For finding all maximal $\delta$-subrepetitions we propose two
algorithms. The first algorithm has $O(\frac{n\log\log n}{\delta^2})$ time
complexity for the case of constant alphabet size and $O(n\log n
+\frac{n\log\log n}{\delta^2})$ time complexity for the general case. The
second algorithm has $O(n\log n+\frac{n}{\delta^2}\log \frac{1}{\delta})$
expected time complexity.


title:
Optical Anisotropy in Bismuth Titanate: An Experimental and Theoretical
  Study

abstract:
  We report experimental and theoretical investigation of anisotropy in optical
properties and their origin in the ferroelectric and paraelectric phases of
bismuth titanate. Room temperature ellipsometric measurements performed on
pulsed laser deposited bismuth titanate thin films of different orientations
show anisotropy in the dielectric and optical constants, Subsequent
first-principles calculations performed on the ground state structures of
ferroelectric and high temperature paraelectric phases of bismuth titanate show
that the material demonstrates anisotropic optical behavior in both
ferroelectric and paraelectric phases. We further show that O 2p to Ti 3d
transition is the primary origin of optical activity of the material while
optical anisotropy results from the asymmetrically oriented Ti-O bonds in TiO6
octehdra in the unit cell.


title: Magnetic Moments of Bottom Baryons: Effective mass and Screened Charge

abstract:
  We calculate the magnetic moments of low lying heavy flavor bottom baryons
using effective quark mass and shielded quark charge scheme. We obtain the
magnetic moments of both $J^P = 1/2^+$ and $J^P = 3/2^+$ baryon states. We
compare our predictions with other theoretical approaches.


title:
Why SOV might be initially preferred and then lost or recovered? A
  theoretical framework

abstract:
  Little is known about why SOV order is initially preferred and then discarded
or recovered. Here we present a framework for understanding these and many
related word order phenomena: the diversity of dominant orders, the existence
of free words orders, the need of alternative word orders and word order
reversions and cycles in evolution. Under that framework, word order is
regarded as a multiconstraint satisfaction problem in which at least two
constraints are in conflict: online memory minimization and maximum
predictability.


title:
Radio frequency induced and neoclassical asymmetries and their effects
  on turbulent impurity transport in a tokamak

abstract:
  Poloidal asymmetries in the impurity density can be generated by radio
frequency heating in the core and by neoclassical effects in the edge of
tokamak plasmas. In a pedestal case study, using global neoclassical
simulations we find that finite orbit width effects can generate significant
poloidal variation in the electrostatic potential, which varies on a small
radial scale. Gyrokinetic modeling shows that these poloidal asymmetries can be
strong enough to significantly modify turbulent impurity peaking. In the
pedestal the ExB drift in the radial electric field can give a larger
contribution to the poloidal motion of impurities than that of their parallel
streaming. Under such circumstances we find that up-down asymmetries can also
affect impurity peaking.


title: Inflation after False Vacuum Decay: Observational Prospects after Planck

abstract:
  We assess two potential signals of the formation of our universe by the decay
of a false vacuum. Negative spatial curvature is one possibility, but the
window for its detection is now small. However, another possible signal is a
suppression of the CMB power spectrum at large angles. This arises from the
steepening of the effective potential as it interpolates between a flat
inflationary plateau and the high barrier separating us from our parent vacuum.
We demonstrate that these two effects can be parametrically separated in
angular scale.
  Observationally, the steepening effect appears to be excluded at large l; but
it remains consistent with the slight lack of power below l about 30 found by
the WMAP and Planck collaborations. We give two simple models which improve the
fit to the Planck data; one with observable curvature and one without. Despite
cosmic variance, we argue that future CMB polarization and most importantly
large-scale structure observations should be able to corroborate the Planck
anomaly if it is real.
  If we further assume the specific theoretical setting of a landscape of
metastable vacua, as suggested by string theory, we can estimate the
probability of seeing a low-l suppression in the CMB. There are significant
theoretical uncertainties in such calculations, but we argue the probability
for a detectable suppression may be as large as O(1), and in general is
significantly larger than the probability of seeing curvature.


title: Learning a Loopy Model For Semantic Segmentation Exactly

abstract:
  Learning structured models using maximum margin techniques has become an
indispensable tool for com- puter vision researchers, as many computer vision
applications can be cast naturally as an image labeling problem. Pixel-based or
superpixel-based conditional random fields are particularly popular examples.
Typ- ically, neighborhood graphs, which contain a large number of cycles, are
used. As exact inference in loopy graphs is NP-hard in general, learning these
models without approximations is usually deemed infeasible. In this work we
show that, despite the theoretical hardness, it is possible to learn loopy
models exactly in practical applications. To this end, we analyze the use of
multiple approximate inference techniques together with cutting plane training
of structural SVMs. We show that our proposed method yields exact solutions
with an optimality guarantees in a computer vision application, for little
additional computational cost. We also propose a dynamic caching scheme to
accelerate training further, yielding runtimes that are comparable with
approximate methods. We hope that this insight can lead to a reconsideration of
the tractability of loopy models in computer vision.


title:
Resource Optimization in Device-to-Device Cellular Systems Using
  Time-Frequency Hopping

abstract:
  We develop a flexible and accurate framework for device-to-device (D2D)
communication in the context of a conventional cellular network, which allows
for time-frequency resources to be either shared or orthogonally partitioned
between the two networks. Using stochastic geometry, we provide accurate
expressions for SINR distributions and average rates, under an assumption of
interference randomization via time and/or frequency hopping, for both
dedicated and shared spectrum approaches. We obtain analytical results in
closed or semi-closed form in high SNR regime, that allow us to easily explore
the impact of key parameters (e.g., the load and hopping probabilities) on the
network performance. In particular, unlike other models, the expressions we
obtain are tractable, i.e., they can be efficiently optimized without extensive
simulation. Using these, we optimize the hopping probabilities for the D2D
links, i.e., how often they should request a time or frequency slot. This can
be viewed as an optimized lower bound to other more sophisticated scheduling
schemes. We also investigate the optimal resource partitions between D2D and
cellular networks when they use orthogonal resources.


title: A new model of dark matter distribution in galaxies

abstract:
  In the absence of the physical understanding of the phenomenon, different
empirical laws have been used as approximation for distribution of dark matter
in galaxies and clusters of galaxies. We suggest a new profile which is not
empirical in nature, but motivated with the physical idea that what we call
dark matter is essentially the gravitational polarization of the quantum vacuum
(containing virtual gravitational dipoles) by the immersed baryonic matter. It
is very important to include this new profile in forthcoming studies of dark
matter halos and to reveal how well it performs in comparison with empirical
profiles. A good agreement of the profile with observational findings would be
the first sign of unexpected gravitational properties of the quantum vacuum.


title:
Estimates for temperature in projectile like fragment in geometric and
  transport models

abstract:
  Projectile like fragments emerging from heavy ion collision have an
excitation energy which is often labeled by a temperature. This temperature was
recently calculated using a geometric model. We expand the geometric model to
include also dynamic effects using a transport model. The temperatures so
deduced agree quite well with values of temperature needed to fit experimental
data.


title: The augmented marking complex of a surface

abstract:
  We build an augmentation of the Masur-Minsky marking complex by
Groves-Manning combinatorial horoballs to obtain a graph we call the augmented
marking complex, $\mathcal{AM}(S)$. Adapting work of Masur-Minsky, we prove
that $\mathcal{AM}(S)$ is quasiisometric to Teichm\"uller space with the
Teichm\"uller metric. A similar construction was independently discovered by
Eskin-Masur-Rafi. We also completely integrate the Masur-Minsky hierarchy
machinery to $\mathcal{AM}(S)$ to build flexible families of uniform
quasigeodesics in Teichm\"uller space. As an application, we give a new proof
of Rafi's distance formula for the Teichm\"uller metric.


title:
A consistent scalar-tensor cosmology for inflation, dark energy and the
  Hubble parameter

abstract:
  A Friedman cosmology is investigated based on scalar-tensor gravitation with
general metric coupling and scalar potential functions. We show that for a
broad class of such functions, the scalar field can be dynamically trapped
using a recently suggested mechanism. The trapped scalar can drive inflation
and accelerated cosmic expansion, compatible with standard requirements. The
inflationary phase admits a natural exit with a value of the Hubble parameter
dictated by the duration of inflation in a parameter independent manner. For
inflationary duration consistent with the GUT description, the resulting Hubble
parameter is found to be consistent with its observed value.


title: Facebook Applications' Installation and Removal: A Temporal Analysis

abstract:
  Facebook applications are one of the reasons for Facebook attractiveness.
Unfortunately, numerous users are not aware of the fact that many malicious
Facebook applications exist. To educate users, to raise users' awareness and to
improve Facebook users' security and privacy, we developed a Firefox add-on
that alerts users to the number of installed applications on their Facebook
profiles. In this study, we present the temporal analysis of the Facebook
applications' installation and removal dataset collected by our add-on. This
dataset consists of information from 2,945 users, collected during a period of
over a year. We used linear regression to analyze our dataset and discovered
the linear connection between the average percentage change of newly installed
Facebook applications and the number of days passed since the user initially
installed our add-on. Additionally, we found out that users who used our
Firefox add-on become more aware of their security and privacy installing on
average fewer new applications. Finally, we discovered that on average 86.4% of
Facebook users install an additional application every 4.2 days.


title:
Tame Class Field Theory for Singular Varieties over Algebraically Closed
  Fields

abstract:
  Let X be a separated scheme of finite type over an algebraically closed field
k and let m be a natural number. By an explicit geometric construction using
torsors we construct a pairing between the first mod m Suslin homology and the
first mod m tame etale cohomology of X. We show that the induced homomorphism
from the mod m Suslin homology to the abelianized tame fundamental group of X
mod m is surjective. It is an isomorphism of finite abelian groups if (m,
char(k)) = 1, and for general m if resolution of singularities holds over k.


title: A Mean Field Model of Layering Instability in Shearing Suspensions

abstract:
  Concentrated suspensions may shear-thin when the suspended particles form
planar sheets that slide over one another with less friction than if the
particles are randomly distributed. In a na\"ive model the suspension is
described by a mean effective viscosity, and particles that collide with each
other redistribute the mean density in the shearing direction. This leads to a
diffusion equation for the particle density. If the viscosity in the unthinned
state is a steeply increasing function of particle density the effective
diffusion coefficient is negative and the diffusion equation, meaningful only
on scales larger than the particle separation, is ill-posed. This singularity
corresponds to the formation of planar sheets of particles and defines a
critical particle density for the onset of shear thinning.


title: Infinitesimal 2-braidings and differential crossed modules

abstract:
  We categorify the notion of an infinitesimal braiding in a linear strict
symmetric monoidal category, leading to the notion of a (strict) infinitesimal
2-braiding in a linear symmetric strict monoidal 2-category. We describe the
associated categorification of the 4-term relation, leading to six categorified
relations. We prove that any infinitesimal 2-braiding gives rise to a flat and
fake flat 2-connection in the configuration space of $n$ particles in the
complex plane, hence to a categorification of the Knizhnik-Zamolodchikov
connection. We discuss infinitesimal 2-braidings in a 2-category naturally
assigned to every differential crossed module, leading to the notion of a
quasi-invariant tensor in a differential crossed module. Finally we prove that
quasi-invariant tensors exist in the differential crossed module associated to
the String Lie-2-algebra.


title: Comment on "Charged vector mesons in a strong magnetic field"

abstract:
  In a recent paper Y. Hidaka and A. Yamamoto [Phys. Rev. D 87 (2013) 094502]
claim -- using both analytical and numerical approaches -- that the charged rho
mesons cannot condense in the vacuum subjected to a strong magnetic field. In
this Comment we point out that both analytical and numerical results of this
paper are consistent with the inhomogeneous rho-meson condensation.
Furthermore, we show that the numerical results of the paper support the
presence of the expected (in quenched lattice QCD) crossover transition driven
by the rho-meson condensation. Finally, we stress that the inhomogeneous
rho-meson condensation is consistent with both Vafa-Witten and Elitzur
theorems.


title:
Almost sure global well posedness for the radial nonlinear Schrodinger
  equation on the unit ball I: the 2D case

abstract:
  Our first purpose is to extend the results from \cite{T} on the radial
defocusing NLS on the disc in $\mathbb{R}^2$ to arbitrary smooth (defocusing)
nonlinearities and show the existence of a well-defined flow on the support of
the Gibbs measure (which is the natural extension of the classical flow for
smooth data). We follow a similar approach as in \cite{BB-1} exploiting certain
additional a priori space-time bounds that are provided by the invariance of
the Gibbs measure.
  Next, we consider the radial focusing equation with cubic nonlinearity (the
mass-subcritical case was studied in \cite{T2}) where the Gibbs measure is
subject to an $L^2$-norm restriction. A phase transition is established, of the
same nature as studied in the work of Lebowitz-Rose-Speer \cite{LRS} on the
torus. For sufficiently small $L^2$-norm, the Gibbs measure is absolutely
continuous with respect to the free measure, and moreover we have a
well-defined dynamics.


title: A rigorous and efficient asymptotic test for power-law cross-correlation

abstract:
  Podobnik and Stanley recently proposed a novel framework, Detrended
Cross-Correlation Analysis, for the analysis of power-law cross-correlation
between two time-series, a phenomenon which occurs widely in physical,
geophysical, financial and numerous additional applications. While highly
promising in these important application domains, to date no rigorous or
efficient statistical test has been proposed which uses the information
provided by DCCA across time-scales for the presence of this power-law
cross-correlation. In this paper we fill this gap by proposing a method based
on DCCA for testing the hypothesis of power-law cross-correlation; the method
synthesizes the information generated by DCCA across time-scales and returns
conservative but practically relevant p-values for the null hypothesis of zero
correlation, which may be efficiently calculated in software. Thus our
proposals generate confidence estimates for a DCCA analysis in a fully
probabilistic fashion.


title:
Three-Dimensional Smoothed Particle Hydrodynamics Method for Simulating
  Free Surface Flows

abstract:
  In this paper, we applied an improved Smoothing Particle Hydrodynamics (SPH)
method by using gradient kernel renormalization in three-dimensional cases. The
purpose of gradient kernel renormalization is to improve the accuracy of
numerical simulation by improving gradient kernel approximation. This method is
implemented for simulating free surface flows, in particular dam break case
with rigid ball structures and the propagation of waves towards a slope in a
rectangular tank.


title:
Uncontrolled disorder effects in fabricating photonic quantum simulators
  on a kagome geometry: A projected-entangled pair state versus exact
  digonalization analysis

abstract:
  We propose a flexible numerical framework for extracting the energy spectra
and photon transfer dynamics of a unit kagome cell with disordered
cavity-cavity couplings under realistic experimental conditions. A
projected-entangled pair state (PEPS) ansatz to the many-photon wavefunction
allows to gain a detailed understanding of the effects of undesirable disorder
in fabricating well-controlled and scalable photonic quantum simulators. The
correlation functions associated with the propagation of two-photon excitations
reveal intriguing interference patterns peculiar to the kagome geometry and
promise at the same time a highly tunable quantum interferometry device with a
signature for the formation of resonant or Fabry-Pe\'rot-like transmission of
photons. Our results justify the use of the proposed PEPS technique for
addressing the role of disorder in such quantum simulators in the microwave
regime and promises a sophisticated numerical machinery for yet further
explorations of the scalability of the resulting kagome arrays. The introduced
methodology and the physical results may also pave the way for unraveling
exotic phases of correlated light on a kagome geometry.


title: An eight-fold optical quasicrystal with cold atoms

abstract:
  We propose a means to realize two-dimensional quasiperiodic structures by
trapping atoms in an optical potential. The structures have eight-fold symmetry
and are closely related to the well-known quasiperiodic octagonal
(Ammann-Beenker) tiling. We describe the geometrical properties of the
structures obtained by tuning parameters of the system. We discuss some
features of the corresponding tight-binding models, and experiments to probe
quantum properties of this optical quasicrystal.


title: Probing the Galactic Origin of the IceCube Excess with Gamma-Rays

abstract:
  The IceCube Collaboration has recently reported evidence for a high-energy
extraterrestrial neutrino flux. During two years of operation 28 events with
energies between 30 TeV and 1.2 PeV were observed while only 10.6 events were
expected from conventional atmospheric backgrounds. The hadronic interactions
responsible for this IceCube excess will also produce a flux of high-energy
gamma-rays that can serve as a probe of source direction and distance. We show
that existing TeV to PeV diffuse gamma-ray limits support the interpretation
that the IceCube excess is mostly of extragalactic origin. However, we point
out that gamma-ray surveys are biased in the Northern Hemisphere whereas the
recent IceCube data tentatively show a weak preference for the Southern Sky.
Possible sub-dominant contributions from Galactic neutrino sources like
remnants of supernovae and hypernovae are marginally consistent with present
gamma-ray limits. This emphasizes the importance of future diffuse TeV to PeV
gamma-ray surveys in the Southern Hemisphere, particularly in the extended
region around the Galactic Center including the Fermi Bubbles.


title: Observation of D0-D0bar Mixing using the CDF II Detector

abstract:
  We measure the time dependence of the ratio of decay rates for D0 -> K+ pi-
to the Cabibbo-favored decay D0 -> K- pi+. The charge conjugate decays are
included. A signal of 3.3 x 10^4 D*+ -> pi+ D0, D0 -> K+ pi- decays is obtained
with D0 proper decay times between 0.75 and 10 mean D0 lifetimes. The data were
recorded with the CDF II detector at the Fermilab Tevatron and correspond to an
integrated luminosity of 9.6 fb-1 for p-pbar collisions at sqrt(s) = 1.96 TeV.
Assuming CP conservation, we search for D0-D0bar mixing and measure the mixing
parameters to be R_D = (3.51 +/- 0.35) x 10^{-3}, y' = (4.3 +/- 4.3) x 10^{-3},
and x'^2 = (0.08 +/- 0.18) x 10^{-3}. We report Bayesian probability intervals
in the x'^2 - y' plane and find that the significance of excluding the
no-mixing hypothesis is equivalent to 6.1 Gaussian standard deviations,
providing the second observation of D0-D0bar mixing from a single experiment.


title:
Enumeration of real curves in CP^{2n-1} and a WDVV relation for real
  Gromov-Witten invariants

abstract:
  We establish a homology relation for the Deligne-Mumford moduli spaces of
real curves which lifts to a WDVV-type relation for real Gromov-Witten
invariants of real symplectic manifolds; we also obtain a vanishing theorem for
these invariants. For many real symplectic manifolds, these results reduce all
genus 0 real invariants with conjugate pairs of constraints to genus 0
invariants with a single conjugate pair of constraints. In particular, we give
a complete recursion for counts of real rational curves in odd-dimensional
projective spaces with conjugate pairs of constraints and specify all cases
when they are nonzero and thus provide non-trivial lower bounds in
high-dimensional real algebraic geometry. We also show that the real invariants
of the three-dimensional projective space with conjugate point constraints are
congruent to their complex analogues modulo 4.


title:
Cartan algorithm and Dirac constraints for Griffiths variational
  problems

abstract:
  Dirac algorithm allows to construct Hamiltonian systems for singular systems,
and so contributing to its successful quantization. A drawback of this method
is that the resulting quantized theory does not have manifest Lorentz
invariance. This motivated the quest of alternatives to the usual Hamiltonian
theory on the space of sections; a particular instance of this search is the so
called restricted Hamiltonian theory, where the equations of motion of a field
theory are formulated by means of a multisymplectic structure, a kind of
generalization of the symplectic form to the multidimensional context, and even
a constraint algorithm working in this context has been proposed. In the
present article we will try to provide partial aswers to two questions
intimately related with these issues: First, to assign multisymplectic spaces
to variational problems in the Griffiths formalism in such a way that the
equations of motion can be written as restricted Hamiltonian systems, and
second, to propose a covariant Dirac-like algorithm suitable to work with them;
it must be recalled that given the Griffiths formalism contains the classical
variational problems as particular instances, it yields to a novel covariant
algorithm for deal with constraints in field theory. Moreover, in this
formulation the constraint algorithm becomes simply the Cartan algorithm
designed for deal with Pfaffian systems.


title:
Carrier dynamics in site- and structure-controlled InGaN/GaN quantum
  dots

abstract:
  We report on the carrier dynamics in InGaN/GaN disk-in-a-wire quantum dots
with precisely controlled location and structural parameters, including
diameter, thickness and material composition. We measured the time-integrated
and time-resolved spectra and the second-order correlation function of the
photoluminescence from quantum dots with diameters ranging from 19 nm to 33 nm
at temperatures of 10 K to 120 K. The influence of the small fluctuations in
structural parameters, most importantly the quantum dot thickness, on the
optical properties are also investigated through statistical correlations among
multiple optical properties of many individual quantum dots. We found that in a
single dot the strain-induced polarization field and the strain relaxation at
the sidewall form a potential barrier to protect the exciton from reaching the
sidewall surface. However, the exciton can overcome this potential barrier and
recombine nonradiatively at the surface through two mechanisms: tunnelling
through the barrier quantum mechanically and hopping over the barrier by
attaining sufficient thermal energy. The former (latter) mechanism is
temperature insensitive (sensitive) and dominates nonradiaitve exciton decay at
low (high) temperatures. We also found that despite the good uniformities in
structural parameters, all optical properties still exhibit inhomogeneities
from dot to dot. However, all these inhomogeneities can be modeled by simply
varying the potential barrier height, which also explains the observed
correlation curves among all optical properties. Finally, we found that the
biexciton-to-exciton quantum efficiency ratio, which determines the probability
of multi-photon emission, can be tuned by adjusting the potential barrier
height and the temperature, suggesting a new way to achieve single photon
emission at high temperatures.


title: Particle Production during Inflation in Light of PLANCK

abstract:
  We consider trapped inflation in a higher dimensional field space: particle
production at a dense distribution of extra species points leads to a terminal
velocity at which inflation can be driven in steep potentials. We compute an
additional, nearly scale invariant contribution to the power-spectrum, caused
by back-scattering of the continuously produced particles. Since this
contribution has a blue tilt, it has to be sub-dominant, leading to an upper
bound on the coupling constant between the inflatons and the extra species
particles. The remaining allowed parameter space is narrow.


title: A next-to-leading Luescher formula

abstract:
  We propose a next-to-leading Luescher-like formula for the finite-size
corrections of the excited states energies in integrable theories. We
conjecture the expressions of the corrections for both the energy and the
particles' rapidities by interpreting the excited states as momenta-dependent
defects. We check the resulting formulas in some simple relativistic model and
conjecture those for the AdS5/CFT4 case.


title:
Unified meta-theory of information, consciousness, time and the
  classical-quantum universe

abstract:
  As time advances in our perceived real world, existing information is
preserved and new information is added to history. All the information that may
ever be encoded in history must be about some fundamental, unique, atemporal
and pre-physical structure: the bare world. Scientists invent model worlds to
efficiently explain aspects of the real world. This paper explores the features
of and relationships between the bare, real, and model worlds. Time -- past,
present and future -- is naturally explained. Both quantum uncertainty and
state reduction are needed for time to progress, since unpredictable new
information must be added to history. Deterministic evolution preserves
existing information. Finite, but steadily increasing, information about the
bare world is jointly encoded in equally uncertain spacetime geometry and
quantum matter. Because geometry holds no information independent of matter,
there is no need to quantize gravity. At the origin of time, information goes
to zero and geometry and matter fade away.


title:
Multiobjective Tactical Planning under Uncertainty for Air Traffic Flow
  and Capacity Management

abstract:
  We investigate a method to deal with congestion of sectors and delays in the
tactical phase of air traffic flow and capacity management. It relies on
temporal objectives given for every point of the flight plans and shared among
the controllers in order to create a collaborative environment. This would
enhance the transition from the network view of the flow management to the
local view of air traffic control. Uncertainty is modeled at the trajectory
level with temporal information on the boundary points of the crossed sectors
and then, we infer the probabilistic occupancy count. Therefore, we can model
the accuracy of the trajectory prediction in the optimization process in order
to fix some safety margins. On the one hand, more accurate is our prediction;
more efficient will be the proposed solutions, because of the tighter safety
margins. On the other hand, when uncertainty is not negligible, the proposed
solutions will be more robust to disruptions. Furthermore, a multiobjective
algorithm is used to find the tradeoff between the delays and congestion, which
are antagonist in airspace with high traffic density. The flow management
position can choose manually, or automatically with a preference-based
algorithm, the adequate solution. This method is tested against two instances,
one with 10 flights and 5 sectors and one with 300 flights and 16 sectors.


title: The Ionized Nebula surrounding the Red Supergiant W26 in Westerlund 1

abstract:
  We present H\alpha images of an ionized nebula surrounding the M2-5Ia red
supergiant (RSG) W26 in the massive star cluster Westerlund 1. The nebula
consists of a circumstellar shell or ring ~0.1pc in diameter and a triangular
nebula ~0.2pc from the star that in high-resolution Hubble Space Telescope
images shows a complex filamentary structure. The excitation mechanism of both
regions is unclear since RSGs are too cool to produce ionizing photons and we
consider various possibilities. The presence of the nebula, high stellar
luminosity and spectral variability suggest that W26 is a highly evolved RSG
experiencing extreme levels of mass-loss. As the only known example of an
ionized nebula surrounding a RSG W26 deserves further attention to improve our
understanding of the final evolutionary stages of massive stars.


title: Direct Detection of SDSS J0926+3624 Orbital Expansion with ARCONS

abstract:
  AM Canum Venaticorum (AM CVn) stars belong to a class of ultra-compact, short
period binaries with spectra dominated largely by helium. SDSS J0926+3624 is of
particular interest as it is the first observed eclipsing AM CVn system. We
observed SDSS J0926+3624 with the \textbf{Ar}ray \textbf{C}amera for
\textbf{O}ptical to \textbf{N}ear-IR \textbf{S}pectrophotometry (ARCONS) at the
Palomar 200" telescope. ARCONS uses a relatively new type of energy-resolved
photon counters called Microwave Kinetic Inductance Detectors (MKIDs). ARCONS,
sensitive to radiation from 350 to 1100 nm, has a time resolution of several
microseconds and can measure the energy of a photon to $\sim10%$. We present
the light curves for these observations and examine changes in orbital period
from prior observations. Using a quadratic ephemeris model, we measure a period
rate of change $\dot{P} = (3.07 \pm 0.56)\times 10^{-13}$. In addition, we use
the high timing resolution of ARCONS to examine the system's high frequency
variations and search for possible quasi-periodic oscillations (QPOs). Finally,
we use the instrument's spectral resolution to examine the light curves in
various wavelength bands. We do not find any high frequency QPOs or significant
spectral variability throughout an eclipse.


title: Rapidly Fading Supernovae from Massive Star Explosions

abstract:
  Transient surveys have recently discovered a class of supernovae (SNe) with
extremely rapidly declining light curves. These events are also often
relatively faint, especially compared to Type Ia SNe. The common explanation
for these events involves a weak explosion, producing a radioactive outflow
with small ejected mass and kinetic energy (M ~ 0.1 Msun and E ~ 0.1 B,
respectively), perhaps from the detonation of a helium shell on a white dwarf.
We argue, in contrast, that these events may be Type Ib/c SNe with typical
masses and energies (M ~ 3 Msun, E ~ 1 B), but which ejected very little
radioactive material. In our picture, the light curve is powered by the
diffusion of thermal energy deposited by the explosion shock wave, and the
rapid evolution is due to recombination, which reduces the opacity and results
in an "oxygen-plateau" light curve. Using a radiative transfer code, we
generate synthetic spectra and light curves and demonstrate that this model can
reasonably fit the observations of one event, SN 2010X. Similar models may
explain the features of other rapidly evolving SNe such as SN 2002bj and SN
2005ek. SNe such as these require stripped-envelope progenitors with rather
large radii (R ~ 20 Rsun), which may originate from a mass loss episode
occurring just prior to explosion.


title: Out of Equilibrium Temperature from Holography

abstract:
  We define an effective temperature and study its properties for a class of
out-of-equilibrium steady states in a heat bath. Our analysis is based on the
anti-de Sitter spacetime/conformal field theory (AdS/CFT) correspondence, and
examples include systems driven by applied electric fields and branes dragged
in plasmas. We found that the effective temperature can be lower than that of
the heat bath and that the out-of-equilibrium noise can be smaller than that in
equilibrium. We show that a generalization of the fluctuation-dissipation
relation holds for the effective temperature. In particular, we generalize the
Johnson-Nyquist relation for large electric field.

categories: hep-th cond-mat.stat-mech cond-mat.str-el gr-qc nucl-th


title: Fragmentation in Dusty Low-Metallicity Star Forming Halos

abstract:
  The first stars in the universe, termed Population III, are thought to have
been very massive compared to the stars that form in the present epoch. As
feedback from the first generation of stars altered the contents of the
interstellar medium, the universe switched to a low-mass mode of star
formation, which continues in the high metallicity stars formed in the present
era. Several studies have investigated the transition between metal-free and
metal-enriched star formation, with tentative evidence being found for a
metallicity threshold near 10^-3.5 Z_sun due to atomic and molecular
transitions and another threshold near 10^-5.5 Z_sun due to dust. In this work,
we simulate the formation of stars in idealized low-metallicity halos using the
AMR code Enzo. We conduct several simulations of 10^6 M_sun and 10^7 M_sun
halos in which the metal content, initial rotation, and degree of turbulence
are varied in order to study the effect of these properties on gas
fragmentation over a range of densities. We find tentative support for the idea
of a critical metallicity, but the effect of varying metallicity on the gas we
observe is not as dramatic as what has been reported in earlier studies. We
find no clear relation between the initial spin or the initial level of
turbulence in the halo and the final properties of the gas contained therein.
Additionally, we find that the degree to which the Jeans length is refined, the
initial density profile of the gas, and the inclusion of deuterium chemistry
each have a significant effect on the evolution and fragmentation of the gas in
the halo - in particular, we find that at least 64 grid cells are needed to
cover the Jeans length in order to properly resolve the fragmentation.


title:
Constraining Light Dark Matter with Diffuse X-Ray and Gamma-Ray
  Observations

abstract:
  We present constraints on decaying and annihilating dark matter (DM) in the 4
keV to 10 GeV mass range, using published results from the satellites HEAO-1,
INTEGRAL, COMPTEL, EGRET, and the Fermi Gamma-ray Space Telescope. We derive
analytic expressions for the gamma-ray spectra from various DM decay modes, and
find lifetime constraints in the range 10^24-10^28 sec, depending on the DM
mass and decay mode. We map these constraints onto the parameter space for a
variety of models, including a hidden photino that is part of a kinetically
mixed hidden sector, a gravitino with R-parity violating decays, a sterile
neutrino, DM with a dipole moment, and a dark pion. The indirect constraints on
sterile-neutrino and hidden-photino DM are found to be more powerful than other
experimental or astrophysical probes in some parts of parameter space. While
our focus is on decaying DM, we also present constraints on DM annihilation to
electron-positron pairs. We find that if the annihilation is p-wave suppressed,
the galactic diffuse constraints are, depending on the DM mass and velocity at
recombination, more powerful than the constraints from the Cosmic Microwave
Background.


title: WIMP-nucleon scattering with heavy WIMP effective theory

abstract:
  The discovery of a Standard Model-like Higgs boson and the hitherto absence
of evidence for other new states may indicate that if WIMPs comprise
cosmological dark matter, they are heavy compared to electroweak scale
particles, $M \gg m_{W^\pm}, m_{Z^0}$. In this limit, the absolute cross
section for a WIMP of given electroweak quantum numbers to scatter from a
nucleon becomes computable in terms of Standard Model parameters. We develop
effective field theory techniques to analyze the heavy WIMP limit of
WIMP-nucleon scattering, and present the first complete calculation of the
leading spin-independent cross section in Standard Model extensions consisting
of one or two electroweak $SU(2)_W \times U(1)_Y$ multiplets.


title:
The Intrinsic Scatter Along The Main Sequence of Star-Forming Galaxies
  at z ~ 0.7

abstract:
  A sample of 12614 star-forming galaxies (SFGs) with stellar mass >10^9.5
M_sun between 0.6<z<0.8 from COSMOS is selected to study the intrinsic scatter
of the correlation between star formation rate (SFR) and stellar mass. We
derive SFR from ultraviolet (UV) and infrared (IR) luminosities. A stacking
technique is adopted to measure IR emission for galaxies undetected at 24
micron. We confirm that the slope of the mass-SFR relation is close to unity.
We examine the distributions of specific SFRs (SSFRs) in four equally spaced
mass bins from 10^9.5 M_sun to 10^11.5 M_sun. Different models are used to
constrain the scatter of SSFR for lower mass galaxies that are mostly
undetected at 24 micron. The SFR scatter is dominated by the scatter of UV
luminosity and gradually that of IR luminosity at increasing stellar mass. We
derive SSFR dispersions of 0.18, 0.21, 0.26 and 0.31 dex with a typical
measurement uncertainty of <~ 0.01 dex for the four mass bins. Interestingly,
the scatter of the mass-SFR relation seems not constant in the sense that the
scatter in SSFR is smaller for SFGs of stellar mass <10^10.5 M_sun. If
confirmed, this suggests that the physical processes governing star formation
become systematically less violent for less massive galaxies. The SSFR
distribution for SFGs with intermediate mass 10^10-10^10.5 M_sun is
characterized by a prominent excess of intense starbursts in comparison with
other mass bins. We argue that this feature reflects that both violent (e.g.,
major/minor mergers) and quiescent processes are important in regulating star
formation in this intermediate mass regime.


title:
Impact of baryons on the cluster mass function and cosmological
  parameter determination

abstract:
  Recent results by the Planck collaboration have shown that cosmological
parameters derived from the cosmic microwave background anisotropies and
cluster number counts are in tension, with the latter preferring lower values
of the matter density parameter, $\Omega_\mathrm{m}$, and power spectrum
amplitude, $\sigma_8$. Motivated by this, we investigate the extent to which
the tension may be ameliorated once the effect of baryonic depletion on the
cluster mass function is taken into account. We use the large-volume Millennium
Gas simulations in our study, including one where the gas is pre-heated at high
redshift and one where the gas is heated by stars and active galactic nuclei
(in the latter, the self-gravity of the baryons and radiative cooling are
omitted). In both cases, the cluster baryon fractions are in reasonably good
agreement with the data at low redshift, showing significant depletion of
baryons with respect to the cosmic mean. As a result, it is found that the
cluster abundance in these simulations is around 15 per cent lower than the
commonly-adopted fit to dark matter simulations by Tinker et al (2008) for the
mass range $10^{14}-10^{14.5}h^{-1} \mathrm{M}_\odot$. Ignoring this effect
produces a significant artificial shift in cosmological parameters which can be
expressed as $\Delta[\sigma_8(\Omega_\mathrm{m}/0.27)^{0.38}]\simeq -0.03$ at
$z=0.17$ (the median redshift of the $\mathit{Planck}$ cluster sample) for the
feedback model. While this shift is not sufficient to fully explain the
$\mathit{Planck}$ discrepancy, it is clear that such an effect cannot be
ignored in future precision measurements of cosmological parameters with
clusters. Finally, we outline a simple, model-independent procedure that
attempts to correct for the effect of baryonic depletion and show that it works
if the baryon-dark matter back-reaction is negligible.


title:
Scale Invariance plus Unitarity Implies Conformal Invariance in Four
  Dimensions

abstract:
  We give a non-perturbative proof that any 4D unitary and Lorentz-invariant
quantum field theory with a conserved scale current is in fact conformally
invariant. We show that any scale invariant theory (unitary or not) must have
either a vanishing anomaly for global scale transformations or an operator of
spin 2 and dimension 2. Neither of these possibilities is allowed for unitary
theories, proving the result. This is also a strong constraint on non-unitary
Euclidean theories with scale but not conformal invariance, suggesting the
conjecture that all such theories are free field theories.


title:
Mergers in Galaxy Groups - I. Structure and Properties of Elliptical
  Remnants

abstract:
  We present collisionless simulations of dry mergers in groups of three to
twenty-five galaxies to test the hypothesis that elliptical galaxies form at
the centers of such groups. Mock observations of the central remnants confirm
their similarity to ellipticals, despite having no dissipational component. We
vary the profile of the original spiral's bulge and find that ellipticals
formed from spirals with exponential bulges have too low Sersic indices.
Mergers of spirals with de Vaucouleurs (classical) bulges produce remnants with
larger Sersic indices correlated with luminosity, as with SDSS ellipticals.
Exponential bulge mergers are better fits to faint ellipticals, whereas
classical bulge mergers better match luminous ellipticals. Similarly, luminous
ellipticals are better reproduced by remnants undergoing many (>5) mergers, and
fainter ellipticals by those with fewer mergers.
  The remnants follow tight size-luminosity and velocity dispersion-luminosity
(Faber-Jackson) relations (<0.12 dex scatter), demonstrating that stochastic
merging can produce tight scaling relations if the merging galaxies also follow
tight scaling relations. The slopes of the size-luminosity and Faber-Jackson
relations are close to observations but slightly shallower in the former case.
Both relations' intercepts are offset - remnants are too large but have too low
dispersions at fixed luminosity. Some remnants show substantial (v/\sigma >
0.1) rotational support, although most are slow rotators and few are very fast
rotators (v/\sigma > 0.5).
  These findings contrast with previous studies concluding that dissipation
necessary to produce ellipticals from binary mergers of spirals. Multiple,
mostly minor and dry mergers can produce bright ellipticals, whereas
significant dissipation could be required to produce faint, rapidly-rotating
ellipticals.


title: Seeing Hofstadter's Butterfly in Atomic Fermi Gases

abstract:
  We propose a novel way to detect the fractal energy spectrum of the
Hofstadter model from the density distributions of ultracold fermions in an
external trap. At low temperature, the local compressibility is proportional to
the density of states of the system which reveals the fractal energy spectrum.
However, thermal broadening and noises in the real experimental situation
inevitably smear out fine features in the density distribution. To overcome
this difficulty, we use the maximum entropy method to extract the density of
states directly from the noisy thermal density distributions. Simulations show
that one is able to restore the core feature of the Hofstadter's butterfly
spectrum with current experimental techniques. By further reducing the noise or
the temperature, one can refine the resolution and observe fine structures of
the butterfly spectrum.


title:
The temperature of the diffuse HI in the Milky Way I: High resolution HI
  21 cm absorption studies

abstract:
  We have carried out deep, high velocity resolution, interferometric Galactic
HI 21 cm absorption spectroscopy towards 32 compact extra-galactic radio
sources with the Giant Metrewave Radio Telescope (GMRT) and the Westerbork
Synthesis Radio Telescope (WSRT). The optical depth spectra for most sources
have root mean square noise values \lesssim 10^{-3} per 1 km/s velocity channel
and are thus sufficiently sensitive to detect absorption by warm neutral
hydrogen with HI column densities N_HI \gtrsim 10^{20} cm^{-2}, spin
temperatures T_s \leq 5000 K, and line widths equal to the thermal width (20
km/s). HI 21 cm absorption was detected against all background sources but one,
B0438-436. The spectra of sources observed separately with GMRT and WSRT show
excellent agreement, indicating that spectral baseline problems and
contamination from HI 21 cm emission are negligible. This paper presents the
absorption spectra, the emission spectra along neighbouring sightlines from the
Leiden-Argentine-Bonn survey, and the derived spin temperature spectra. On
every sightline, the maximum spin temperature detected (at \ge 3 sigma
significance) even at a velocity resolution of 1 km/s is \gtrsim 1000 K,
indicating that we are detecting the warm neutral medium along most sightlines.
This is by far the largest sample of Galactic HI 21 cm absorption spectra of
this quality, providing a sensitive probe of physical conditions in the neutral
atomic ISM.


title:
The temperature of the diffuse HI in the Milky Way II: Gaussian
  decomposition of the HI 21 cm absorption spectra

abstract:
  We discuss physical conditions in Galactic neutral hydrogen based on deep,
high velocity resolution interferometric HI 21 cm absorption spectroscopy
towards 33 compact extra-galactic radio sources. The HI 21 cm optical depth
spectra have root-mean-square noise values \lesssim 10^{-3} per 1 km/s velocity
channel, i.e., sufficiently sensitive to detect HI 21 cm absorption by the warm
neutral medium (WNM). Comparing these spectra with HI 21 cm emission spectra
from the Leiden-Argentine-Bonn (LAB) survey, we show that some of the
absorption detected on most sightlines must arise in gas with temperatures
higher than that in the stable cold neutral medium (CNM). A multi-Gaussian
decomposition of 30 of the HI 21 cm absorption spectra yielded very few
components with line widths in the temperature range of stable WNM, with no
such WNM components detected for sixteen of the thirty sightlines. We find that
some of the detected HI 21 cm absorption along thirteen of these sightlines
must arise in gas with spin temperatures larger than the CNM range. For these
sightlines, we use very conservative estimates of the CNM spin temperature and
the non-thermal broadening to derive strict upper limits to the gas column
densities in the CNM and WNM phases. Comparing these upper limits to the total
HI column density, we find that typically at least 28% of the gas must have
temperatures in the thermally unstable range (200-5000 K). Our observations
hence robustly indicate that a significant fraction of the gas in the Galactic
interstellar medium has temperatures outside the ranges expected for thermally
stable gas in two-phase models.


title:
UB CCD photometry of the old, metal rich, open clusters NGC 6791, NGC
  6819 and NGC 7142

abstract:
  We report on a UV-oriented imaging survey in the fields of the old,
metal-rich open clusters, NGC 6791, NGC 6819 and NGC 7142. These three clusters
represent both very near and ideal stellar aggregates to match the distinctive
properties of the evolved stellar populations, as in elliptical galaxies and
bulges of spirals. The CMD of the three clusters is analyzed in detail, with
special emphasis to the hot stellar component. We report, in this regard, one
new extreme horizontal-branch star candidate in NGC 6791. For NGC 6819 and
7142, the stellar luminosity function points to a looser radial distribution of
faint lower Main Sequence stars, either as a consequence of cluster dynamical
interaction with the Galaxy or as an effect of an increasing fraction of binary
stars toward the cluster core, as actually observed in NGC 6791 too.


title: Endomotives of toric varieties

abstract:
  We construct endomotives associated to toric varieties, in terms of the
decomposition of a toric variety into torus orbits and the action of a
semigroup of toric morphisms. We show that the endomotives can be endowed with
time evolutions and we discuss the resulting quantum statistical mechanical
systems. We show that, in particular, one can construct a time evolution
related to the logarithmic height function. We discuss relations to
F1-geometry.


title: Isothermal dust models of Herschel-ATLAS galaxies

abstract:
  We use galaxies from the Herschel-ATLAS survey, and a suite of ancillary
simulations based on an isothermal dust model, to study our ability to
determine the effective dust temperature, luminosity and emissivity index of
250um selected galaxies in the local Universe (z < 0.5). As well as simple
far-infrared SED fitting of individual galaxies based on chi^2 minimisation, we
attempt to derive the best global isothermal properties of 13,826 galaxies with
reliable optical counterparts and spectroscopic redshifts. Using our
simulations, we highlight the fact that applying traditional SED fitting
techniques to noisy observational data in the Herschel Space Observatory bands
introduces artificial anti-correlation between derived values of dust
temperature and emissivity index. This is true even for galaxies with the most
robust detections in our sample, making the results hard to interpret. We apply
a method to determine the best-fit global values of isothermal effective
temperature and emissivity index for z < 0.5 galaxies in H-ATLAS, deriving T =
22.3 +/- 0.1K and Beta = 1.98 +/- 0.02 (or T = 23.5 +/- 0.1K and Beta = 1.82
+/- 0.02 if we attempt to correct for bias by assuming that T and Beta are
independent and normally distributed). We use our technique to test for an
evolving emissivity index, finding only weak evidence. The median dust
luminosity of our sample is log(Ldust/Lsolar) = 10.72 +/- 0.05 which (unlike T)
shows little dependence on the choice of Beta used in our analysis, including
whether it is variable or fixed. We use a further suite of simulations to
emphasise the importance of the H-ATLAS PACS data for deriving dust
temperatures at these redshifts, even though they are less sensitive than the
SPIRE data. The majority of galaxies detected by H-ATLAS are normal
star-forming galaxies, though a substantial minority (~31%) fall in the
Luminous Infrared Galaxy category. (Abridged)


title: Correlating Infall with Deuterium Fractionation in Dense Cores

abstract:
  We present a survey of HCO+ (3-2) observations pointed towards dense cores
with previous measurements of N(N2D+)/N(N2H+). Of the 26 cores in this survey,
five show the spectroscopic signature of outward motion, nine exhibit neither
inward nor outward motion, eleven appear to be infalling, and one is not
detected. We compare the degree of deuterium fractionation with infall
velocities calculated from the HCO+ spectra and find that those cores with
[D]/[H] > 0.1 are more likely to have the signature of inward motions than
cores with smaller [D]/[H] ratios. Infall motions are also much more common in
cores with masses exceeding their thermal Jeans masses. The fastest infall
velocity measured belongs to one of the two protostellar cores in our survey,
L1521F, and the observed motions are typically on the order of the sound speed.


title: High velocity clouds in the Galactic All Sky Survey I. Catalogue

abstract:
  We present a catalogue of high-velocity clouds (HVCs) from the Galactic All
Sky Survey (GASS) of southern-sky neutral hydrogen, which has 57 mK sensitivity
and 1 km/s velocity resolution and was obtained with the Parkes Telescope. Our
catalogue has been derived from the stray-radiation corrected second release of
GASS. We describe the data and our method of identifying HVCs and analyse the
overall properties of the GASS population. We catalogue a total of 1693 HVCs at
declinations < 0 deg, including 1111 positive velocity HVCs and 582 negative
velocity HVCs. Our catalogue also includes 295 anomalous velocity clouds
(AVCs). The cloud line-widths of our HVC population have a median FWHM of ~19
km/s, which is lower than found in previous surveys. The completeness of our
catalogue is above 95% based on comparison with the HIPASS catalogue of HVCs,
upon which we improve with an order of magnitude in spectral resolution. We
find 758 new HVCs and AVCs with no HIPASS counterpart. The GASS catalogue will
shed an unprecedented light on the distribution and kinematic structure of
southern-sky HVCs, as well as delve further into the cloud populations that
make up the anomalous velocity gas of the Milky Way.


title:
Weaving quantum optical frequency combs into continuous-variable
  hypercubic cluster states

abstract:
  Cluster states with higher-dimensional lattices that cannot be physically
embedded in three-dimensional space have important theoretical interest in
quantum computation and quantum simulation of topologically ordered
condensed-matter systems. We present a simple, scalable, top-down method of
entangling the quantum optical frequency comb into hypercubic-lattice
continuous-variable cluster states of a size of about 10^4 quantum field modes,
using existing technology. A hypercubic lattice of dimension D (linear, square,
cubic, hypercubic, etc.) requires but D optical parametric oscillators with
bichromatic pumps whose frequency splittings alone determine the lattice
dimensionality and the number of copies of the state.


title: Non-Abelian Fractional Chern Insulators from Long-Range Interactions

abstract:
  The recent theoretical discovery of fractional Chern insulators (FCIs) has
provided an important new way to realize topologically ordered states in
lattice models. In earlier works, on-site and nearest neighbor Hubbard-like
interactions have been used extensively to stabilize Abelian FCIs in systems
with nearly flat, topologically nontrivial bands. However, attempts to use
two-body interactions to stabilize non-Abelian FCIs, where the ground state in
the presence of impurities can be massively degenerate and manipulated through
anyon braiding, have proven very difficult in uniform lattice systems. Here, we
study the remarkable effect of long-range interactions in a lattice model that
possesses an exactly flat lowest band with a unit Chern number. When spinless
bosons with two-body long-range interactions partially fill the lowest Chern
band, we find convincing evidence of gapped, bosonic Read-Rezayi (RR) phases
with non-Abelian anyon statistics. We characterize these states through
studying topological degeneracies, the overlap between the ground states of
two-body interactions and the exact RR ground states of three- and four-body
interactions, and state counting in the particle-cut entanglement spectrum.
Moreover, we demonstrate how an approximate lattice form of Haldane's
pseudopotentials, analogous to that in the continuum, can be used as an
efficient guiding principle in the search for lattice models with stable
non-Abelian phases.

categories: cond-mat.str-el cond-mat.mes-hall cond-mat.quant-gas quant-ph


title: Random Organization in Periodically Driven Gliding Dislocations

abstract:
  We numerically examine dynamical irreversible to reversible transitions and
random organization for periodically driven gliding dislocation assemblies
using the stroboscopic protocol developed to identify random organization in
periodically driven dilute colloidal suspensions. We find that the gliding
dislocations exhibit features associated with random organization and evolve
into a dynamically reversible state after a transient time extending over a
number of cycles. At a critical shearing amplitude, the transient time
diverges. When the dislocations enter the reversible state they organize into
patterns with fragmented domain wall type features.


title:
Black-hole mass estimates for a homogeneous sample of bright
  flat-spectrum radio quasars

abstract:
  We have selected a complete sample of flat-spectrum radio quasars (FSRQs)
from the WMAP 7-yr catalog within the SDSS area, all with measured redshift,
and have compared the black hole mass estimates based on fitting a standard
accretion disk model to the `blue bump' with those obtained from the commonly
used single epoch virial method. The sample comprises 79 objects with a flux
density limit of 1 Jy at 23 GHz, 54 of which (68%) have a clearly detected
`blue bump'. Thirty-four of the latter have, in the literature, black hole mass
estimates obtained with the virial method. The mass estimates obtained from the
two methods are well correlated. If the calibration factor of the virial
relation is set to $f=4.5$, well within the range of recent estimates, the mean
logarithmic ratio of the two mass estimates is equal to zero with a dispersion
close to the estimated uncertainty of the virial method. The fact that the two
independent methods agree so closely in spite of the potentially large
uncertainties associated with each lends strong support to both of them. The
distribution of black-hole masses for the 54 FSRQs in our sample with a well
detected blue bump has a median value of $7.4\times 10^{8}\,M_\odot$. It
declines at the low mass end, consistent with other indications that radio loud
AGNs are generally associated with the most massive black holes, although the
decline may be, at least partly, due to the source selection. The distribution
drops above $\log(M_\bullet/M_\odot) = 9.4$, implying that ultra-massive black
holes associated with FSRQs must be rare.


title:
Algorithms for Computing Topological Invariants in 2D and 3D Digital
  Spaces

abstract:
  Based on previous results of digital topology, this paper focuses on
algorithms of topological invariants of objects in 2D and 3D Digital Spaces. We
specifically interest in solving hole counting of 2D objects and genus of
closed surface in 3D. We first prove a new formula for hole counting in 2D. The
number of of holes is $h=1 + (|C_4|-|C_2|)/4$ where $C_4$ and $C_2$ are sets of
inward and outward corner points, respectively.
  This paper mainly deals with algorithm design and implementation of practical
computation of topological invariants in digital space. The algorithms relating
to data structures, and pathological case detection and original data
modification are main issues.
  This paper designed fast algorithms for topological invariants such as
connected components, hole counting in 2D and boundary surface genus for 3D.
For 2D images, we designed a linear time algorithm to solve hole counting
problem. In 3D, we designed also O(n) time algorithm to get genus of the closed
surface. These two algorithms are both in $O(\log n)$ space complexity.


title:
GW quasiparticle calculations with spin-orbit coupling for the light
  actinides

abstract:
  We report on the importance of GW self-energy corrections for the electronic
structure of light actinides in the weak-to-intermediate coupling regime. Our
study is based on calculations of the band structure and total density of
states of Np, U, and Pu using a one-shot GW approximation that includes
spin-orbit coupling within a full potential LAPW framework. We also present RPA
screened effective Coulomb interactions for the f-electron orbitals for
different lattice constants, and show that there is an increased contribution
from electron-electron correlation in these systems for expanded lattices. We
find a significant amount of electronic correlation in these highly localized
electronic systems.


title:
Regularized Spectral Clustering under the Degree-Corrected Stochastic
  Blockmodel

abstract:
  Spectral clustering is a fast and popular algorithm for finding clusters in
networks. Recently, Chaudhuri et al. (2012) and Amini et al.(2012) proposed
inspired variations on the algorithm that artificially inflate the node degrees
for improved statistical performance. The current paper extends the previous
statistical estimation results to the more canonical spectral clustering
algorithm in a way that removes any assumption on the minimum degree and
provides guidance on the choice of the tuning parameter. Moreover, our results
show how the "star shape" in the eigenvectors--a common feature of empirical
networks--can be explained by the Degree-Corrected Stochastic Blockmodel and
the Extended Planted Partition model, two statistical models that allow for
highly heterogeneous degrees. Throughout, the paper characterizes and justifies
several of the variations of the spectral clustering algorithm in terms of
these models.


title: On the security of the Kirchhoff-law-Johnson-noise (KLJN) communicator

abstract:
  A simple and general proof is given for the information theoretic
(unconditional) security of the Kirchhoff-law-Johnson-noise (KLJN) key exchange
system under practical conditions. The unconditional security for ideal
circumstances, which is based on the Second Law of Thermodynamics, is found to
prevail even under slightly non-ideal conditions. This security level is
guaranteed by the continuity of functions describing classical physical linear,
as well as stable non-linear, systems. Even without privacy amplification,
Eve's probability for successful bit-guessing is found to converge towards 0.5
- i.e., the perfect security level - when ideal conditions are approached.


title: Oskar Klein and the fifth dimension

abstract:
  After a short biographical summary of the scientific life of Oskar Klein, a
more detailed and hopefully didactic presentation of his derivation of the
relativistic Klein-Gordon wave equation is given. It was a result coming out of
his unification of electromagnetism and gravitation based on Einstein's general
theory of relativity in a five-dimensional spacetime. This idea had previously
been explored by Kaluza, but Klein made it more acceptable by suggesting that
the extra dimension could be compactified and therefore remain unobservable
when it is small enough.


title: Random bits, true and unbiased, from atmospheric turbulence

abstract:
  Random numbers represent a fundamental ingredient for numerical simulation,
games, informa- tion science and secure communication. Algorithmic and
deterministic generators are affected by insufficient information entropy. On
the other hand, suitable physical processes manifest intrinsic unpredictability
that may be exploited for generating genuine random numbers with an entropy
reaching the ideal limit. In this work, we present a method to extract genuine
random bits by using the atmospheric turbulence: by sending a laser beam along
a 143Km free-space link, we took advantage of the chaotic behavior of air
refractive index in the optical propagation. Random numbers are then obtained
by converting in digital units the aberrations and distortions of the received
laser wave-front. The generated numbers, obtained without any post-processing,
pass the most selective randomness tests. The core of our extracting algorithm
can be easily generalized for other physical processes.


title:
Pulsation and Mass Loss Across the HR Diagram: From OB stars to Cepheids
  to Red Supergiants

abstract:
  Both pulsation and mass loss are commonly observed in stars and are important
ingredients for understanding stellar evolution and structure, especially for
massive stars. There is a growing body of evidence that pulsation can also
drive and enhance mass loss in massive stars and that pulsation-driven mass
loss is important for stellar evolution. In this review, I will discuss recent
advances in understanding pulsation driven mass loss in massive main sequence
stars, classical Cepheids and red supergiants and present some challenges
remaining.


title: Ultrametric dynamics for the closed fractal-cluster resource models

abstract:
  The evolutional scenario of the resource distribution in the fractal-cluster
systems which is identified as an "organism" has been suggested. We propose a
model in which the resource redistribution dynamics in the closed system is
determined by the ultrametric structure of the system's space. Moreover, each
cluster has its own character time of a transfer to the equilibrium state which
is determined by the ultrametric size of the cluster. The general equation
which determines this dynamics has been written. For the determined type of the
resource transitions among clusters, the solution to this equation has been
numerically received. The problem of the parameter's identification modeling
for the real systems has been discussed.


title:
Long-term polarization observations of Mira variable stars suggest
  asymmetric structures

abstract:
  Mira and semi-regular variable stars have been studied for centuries but
continue to be enigmatic. One unsolved mystery is the presence of polarization
from these stars. In particular, we present 40 years of polarization
measurements for the prototype o Ceti and V CVn and find very different
phenomena for each star. The polarization fraction and position angle for Mira
is found to be small and highly variable. On the other hand, the polarization
fraction for V CVn is large and variable, from 2 - 7 %, and its position angle
is approximately constant, suggesting a long-term asymmetric structure. We
suggest a number of potential scenarios to explain these observations.


title:
Asteroseismology, standard candles and the Hubble Constant: what is the
  role of asteroseismology in the era of precision cosmology?

abstract:
  Classical Cepheids form one of the foundations of modern cosmology and the
extragalactic distance scale, however, cosmic microwave background observations
measure cosmological parameters and indirectly the Hubble Constant, H0, to
unparalleled precision. The coming decade will provide opportunities to measure
H0 to 2% uncertainty thanks to the GAIA satellite, JWST, ELTs and other
telescopes using Cepheids and other standard candles. In this work, we discuss
the upcoming role for variable stars and asteroseismology in calibrating the
distance scale and measuring H0 and what problems exist in understanding these
stars that will feedback on these measurements.


title:
Superorbital Periodic Modulation in Wind-Accretion High-Mass X-ray
  Binaries from Swift BAT Observations

abstract:
  We report the discovery using data from the Swift Burst Alert Telescope (BAT)
of superorbital modulation in the wind-accretion supergiant high-mass X-ray
binaries 4U 1909+07 (= X 1908+075), IGR J16418-4532, and IGR J16479-4514.
Together with already known superorbital periodicities in 2S 0114+650 and IGR
J16493-4348, the systems exhibit a monotonic relationship between superorbital
and orbital periods. These systems include both supergiant fast X-ray
transients (SFXTs) and classical supergiant systems, and have a range of
inclination angles. This suggests an underlying physical mechanism which is
connected to the orbital period. In addition to these sources with clear
detections of superorbital periods, IGR J16393-4643 (= AX J16390.4-4642) is
identified as a system that may have superorbital modulation due to the
coincidence of low-amplitude peaks in power spectra derived from BAT, RXTE PCA,
and INTEGRAL light curves. 1E 1145.1-6141 may also be worthy of further
attention due to the amount of low-frequency modulation of its light curve.
However, we find that the presence of superorbital modulation is not a
universal feature of wind-accretion supergiant X-ray binaries.


title: Red bulgeless galaxies in SDSS DR7. Are there any AGN hosts?

abstract:
  With the main goal of finding bulgeless galaxies harbouring super massive
black holes and showing, at most, just residual star formation activity, we
have selected a sample of massive bulgeless red sequence galaxies from the
SDSS-DR7, based on the NYU-VAGC catalogue. Multivavelength data were retrieved
using EURO-VO tools, and the objects are characterised in terms of degree of
star formation and the presence of an AGN. We have found seven objects that are
quenched massive galaxies, that have no prominent bulge and that show signs of
extra activity in their nuclei, five of them being central in their halo. These
objects are rather robust candidates for rare systems that, though devoid of a
significant bulge, harbor a supermassive black hole with an activity level
likely capable of having halted the star formation through feedback.


title:
Tuning the Competition between Ferromagnetism and Antiferromagnetism in
  a Half-doped Manganite through Magnetoelectric Coupling

abstract:
  We investigate the possibility of controlling the magnetic phase transition
of the heterointerface between a half-doped manganite
La$_{0.5}$Ca$_{0.5}$MnO$_{3}$ and a multiferroic BiFeO$_{3}$ through
magnetoelectric coupling. Using macroscopic magnetometry and element-selective
x-ray magnetic circular dichroism at the Mn and Fe \emph{L}-edges, we discover
that the ferroelectric polarization of BFO controls simultaneously the
magnetization of BFO and LCMO. X-ray absorption spectra at oxygen \emph{K}-edge
and linear dichroism at Mn \emph{L}-edge suggest that the interfacial coupling
is mainly derived from the superexchange between Mn and Fe \emph{t}$_{2g}$
spins. The combination of x-ray absorption spectroscopy and mean field theory
calculations reveals that the \emph{d}-electron modulation of Mn cations
changes the magnetic coupling in LCMO, which controls the enhanced canted
moments of interfacial BFO via the interfacial coupling. Our results
demonstrate that the competition between ferromagnetic and antiferromagnetic
instability can be modulated by an electric field at the heterointerface,
providing another pathway for the electrical field control of magnetism.


title: Arboreal Singularities

abstract:
  We introduce a class of combinatorial singularities of Lagrangian skeleta of
symplectic manifolds. The link of each singularity is a finite regular cell
complex homotopy equivalent to a bouquet of spheres. It is determined by its
face poset which is naturally constructed starting from a tree (nonempty finite
acyclic graph). The choice of a root vertex of the tree leads to a natural
front projection of the singularity along with an orientation of the edges of
the tree. Microlocal sheaves along the singularity, calculated via the front
projection, are equivalent to modules over the quiver given by the directed
tree.


title: Reduction of Lie-Jordan algebras: Classical

abstract:
  In this paper we present a unified algebraic framework to discuss the
reduction of classical and quantum systems. The underlying algebraic structure
is a Lie-Jordan algebra supplemented, in the quantum case, with a Banach
structure. We discuss the reduction by symmetries, by constraints as well as
the possible, non trivial, combinations of both. We finally introduce a new,
general framework to perform the reduction of physical systems in an algebraic
setup.


title: Reduction of Lie--Jordan algebras: Quantum

abstract:
  In this paper we present a theory of reduction of quantum systems in the
presence of symmetries and constraints. The language used is that of
Lie--Jordan Banach algebras, which are discussed in some detail together with
spectrum properties and the space of states. The reduced Lie--Jordan Banach
algebra is characterized together with the Dirac states on the physical algebra
of observables.


title: Looking Inside a Black Hole

abstract:
  The cosmic censorship conjecture posits that singularities forming to the
future of a regular Cauchy surface are hidden by an event horizon. Consequently
any topological structures will ultimately collapse within the horizon of a set
of black holes and so no observer can actively probe them classically. We
consider here a quantum analog of this problem, in which we compare the
transition rates of an Unruh-DeWitt detector placed outside the horizon of an
eternal BTZ black hole and its associated geon counterpart. We find the
transition rates differ, with the latter being time-dependent, implying that we
are indeed able to probe the structure of the singularity from outside the
Killing horizon.


title: Electron transport in multiterminal networks of Majorana bound states

abstract:
  We investigate electron transport through multiterminal networks hosting
Majorana bound states (MBS) in the framework of full counting statistics (FCS).
In particular, we apply our general results to T-shaped junctions of two
Majorana nanowires. When the wires are in the topologically nontrivial regime,
three MBS are localized near the outer ends of the wires, while one MBS is
localized near the crossing point, and when the lengths of the wires are finite
adjacent MBS can overlap. We propose a combination of current and
cross-correlation measurements to reveal the predicted coupling of four
Majoranas in a topological T~junction. Interestingly, we show that the
elementary transport processes at the central lead are different compared to
the outer leads, giving rise to characteristic non-local signatures in
electronic transport. We find quantitative agreement between our analytical
model and numerical simulations of a tight-binding model. Using the numerical
simulations, we discuss the effect of weak disorder on the current and the
cross-correlation functions.


title: A K3 sigma model with Z_2^8:M_{20} symmetry

abstract:
  The K3 sigma model based on the Z_2-orbifold of the D_4-torus theory is
studied. It is shown that it has an equivalent description in terms of twelve
free Majorana fermions, or as a rational conformal field theory based on the
affine algebra su(2)^6. By combining these different viewpoints we show that
the N=(4,4) preserving symmetries of this theory are described by the discrete
symmetry group Z_2^8:M_{20}. This model therefore accounts for one of the
largest maximal symmetry groups of K3 sigma models. The symmetry group involves
also generators that, from the orbifold point of view, map untwisted and
twisted sector states into one another.


title: Local Well-posedness of A Non-local Burgers Equation

abstract:
  In this paper, we explore a nonlocal inviscid Burgers equation. Fixing a
parameter $h$, we prove existence and uniqueness of the local solution of the
equation $\InviscidBurgersNonlocal{u}$ with periodic initial condition. We also
explore the blow up properties of solutions to these kinds of equations with
given periodic initial data, and show that there exists solutions that blow up
in finite time and solutions that are globally regular. This contrasts with the
classical inviscid Burgers equation, for which all non-constant smooth periodic
initial data lead to finite time blow up. Finally, we present results of
simulations to illustrate our findings.


title:
MUSCLE W49 : A Multi-Scale Continuum and Line Exploration of the Most
  Luminous Star Formation Region in the Milky Way. I. Data and The Mass
  Structure of the Giant Molecular Cloud

abstract:
  The Multi-Scale Continuum and Line Exploration of W49 (MUSCLE W49) is a
comprehensive gas and dust survey of the giant molecular cloud (GMC) of W49A,
the most luminous star-formation region in the Milky Way. It covers the entire
GMC at different scales and angular resolutions. In this paper we present: 1)
an all-configuration SMA mosaic in the 230-GHz band covering the central 3
arcmin (10 pc, known as W49N), with most of the embedded massive stars; and 2)
PMO 14m telescope observations in the 90-GHz band, covering the entire GMC with
maps up to 35 arcmin in size, or 113 pc. We also make use of archival data from
the VLA, JCMT-SCUBA, IRAM 30m, and the CSO BOLOCAM GPS. Our main findings are:
1) The W49 GMC is one of the most massive in the Galaxy, with a total mass
~1.1x10^6 Msun within a radius of 60 pc. Within a radius of 6 pc, the total gas
mass is ~2x10^5 Msun. At these scales only 1% of the material is photoionized.
The mass reservoir is sufficient to form several young massive clusters (YMCs)
as massive as a globular cluster. 2) The mass of the GMC is distributed in a
hierarchical network of filaments. At scales <10 pc, a triple, centrally
condensed structure peaks toward the ring of HC HII regions in W49N. This
structure extends to scales from ~10 to 100 pc. The W49A starburst most likely
formed from global gravitational contraction with localized collapse in a
"hub-filament" geometry. 3) Currently, feedback from the central YMCs (with a
present mass Mcl > 5x10^4 Msun) is still not enough to entirely disrupt the
GMC, but further stellar mass growth could be enough to allow radiation
pressure to clear the cloud and halt star formation. 4) The resulting stellar
content will probably remain as a gravitationally bound massive star cluster,
or a small system of bound clusters. (ABRIDGED)

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


title: Confirmation of Faint Dwarf Galaxies in the M81 Group

abstract:
  We have followed up on the results of a 65 square degree CFHT/MegaCam imaging
survey of the nearby M81 Group searching for faint and ultra-faint dwarf
galaxies. The original survey turned up 22 faint candidate dwarf members. Based
on two-color HST ACS/WFC and WFPC2 photometry, we now confirm 14 of these as
dwarf galaxy members of the group. Distances and stellar population
characteristics are discussed for each. To a completeness limit of M_r' = -10,
we find a galaxy luminosity function slope of -1.27+-0.04 for the M81 group. In
this region, there are now 36 M81 group members known, including 4 blue compact
dwarfs, 8 other late types including the interacting giants M81, NGC 3077, and
M82, 19 early type dwarfs, and at least 5 potential tidal dwarf galaxies. We
find that the dSph galaxies in M81 appear to lie in a flattened distribution,
similar to that found for the Milky Way and M31. One of the newly discovered
dSph galaxies has properties similar to the ultra-faint dwarfs being found in
the Local Group with a size R_e ~ 100 pc and total magnitude estimates M_r' =
-6.8 and M_I ~ -9.1.


title:
Multidimensional Coherent Photocurrent Spectroscopy of a Semiconductor
  Nanostructure

abstract:
  Multidimensional Coherent Optical Photocurrent Spectroscopy (MD-COPS) is
implemented using unstabilized interferometers. Photocurrent from a
semiconductor sample is generated using a sequence of four excitation pulses in
a collinear geometry. Each pulse is tagged with a unique radio frequency
through acousto-optical modulation ; the Four-Wave Mixing (FWM) signal is then
selected in the frequency domain. The interference of an auxiliary continuous
wave laser, which is sent through the same interferometers as the excitation
pulses, is used to synthesize reference frequencies for lock-in detection of
the photocurrent FWM signal. This scheme enables the partial compensation of
mechanical fluctuations in the setup, achieving sufficient phase stability
without the need for active stabilization. The method intrinsically provides
both the real and imaginary parts of the FWM signal as a function of
inter-pulse delays. This signal is subsequently Fourier transformed to create a
multi-dimensional spectrum. Measurements made on the excitonic resonance in a
double InGaAs quantum well embedded in a p-i-n diode demonstrate the technique.


title: Attribute-Efficient Evolvability of Linear Functions

abstract:
  In a seminal paper, Valiant (2006) introduced a computational model for
evolution to address the question of complexity that can arise through
Darwinian mechanisms. Valiant views evolution as a restricted form of
computational learning, where the goal is to evolve a hypothesis that is close
to the ideal function. Feldman (2008) showed that (correlational) statistical
query learning algorithms could be framed as evolutionary mechanisms in
Valiant's model. P. Valiant (2012) considered evolvability of real-valued
functions and also showed that weak-optimization algorithms that use
weak-evaluation oracles could be converted to evolutionary mechanisms.
  In this work, we focus on the complexity of representations of evolutionary
mechanisms. In general, the reductions of Feldman and P. Valiant may result in
intermediate representations that are arbitrarily complex (polynomial-sized
circuits). We argue that biological constraints often dictate that the
representations have low complexity, such as constant depth and fan-in
circuits. We give mechanisms for evolving sparse linear functions under a large
class of smooth distributions. These evolutionary algorithms are
attribute-efficient in the sense that the size of the representations and the
number of generations required depend only on the sparsity of the target
function and the accuracy parameter, but have no dependence on the total number
of attributes.


title:
The Cosmological Constant Problem: Why it's hard to get Dark Energy from
  Micro-physics

abstract:
  These notes present a brief introduction to `naturalness' problems in
cosmology, and to the Cosmological Constant Problem in particular. The main
focus is the `old' cosmological constant problem, though the more recent
variants are also briefly discussed. Several notions of naturalness are
defined, including the closely related ideas of technical naturalness and `t
Hooft naturalness, and it is shown why these naturally arise when cosmology is
embedded within a framework --- effective field theories --- that efficiently
captures what is consistent with what is known about the physics of smaller
distances. Some care is taken to clarify conceptual issues, such as the
relevance or not of quadratic divergences, about which some confusion has
arisen over the years. A set of minimal criteria are formulated against which
proposed solutions to the problem can be judged, and a brief overview made of
the general limitations of most of the approaches. A somewhat more in-depth
discussion is provided of what I view as the most promising approach. These
notes are aimed at graduate students with a basic working knowledge of quantum
field theory and cosmology, but with no detailed knowledge of particle physics.


title: Modularity of some elliptic curves over totally real fields

abstract:
  We investigate modularity of elliptic curves over a general totally real
number field, establishing a finiteness result for the set non-modular
$j$-invariants. By analyzing quadratic points on some modular curves, we show
that all elliptic curves over certain real quadratic fields are modular.


title: Dimuon production from in-medium rho decays from QCD sum rules

abstract:
  We compute the dimuon-excess invariant mass distribution at the rho-meson
peak in the context of relativistic heavy-ion collisions at SPS energies. The
temperature, T, and chemical potential, mu, dependent parameters describing the
rho-meson --its width, mass and leptonic decay constant-- are determined from
finite energy QCD sum rules. Results show that the rho-meson width increases
whereas its mass and leptonic decay constant decrease near the (chemical
potential-dependent) critical temperature T_c(mu) for chiral symmetry
restoration/quark-gluon deconfinement. As a consequence, starting from T_c(mu),
for a short lived cooling the main effect is a broadening of the dimuon
distribution. However, when the evolution brings the system to a lower
freeze-out temperature, with the rho-meson parameters approaching their vacuum
values, the dimuon distribution shows a broad peak centered at the vacuum
rho-meson mass. For even lower freeze-out temperatures the peak becomes less
prominent since the thermal phase space factor suppresses the distribution for
larger values of the invariant dimuon mass, given that the average temperature
is smaller. The dimuon distribution exhibits a non-trivial behavior with mu.
For small mu values the distribution broadens with increasing mu becoming a bit
steeper at low invariant masses for larger values of mu. Our results are in
very good agreement with data from the NA60 Collaboration.


title:
Compression via Compressive Sensing : A Low-Power Framework for the
  Telemonitoring of Multi-Channel Physiological Signals

abstract:
  Telehealth and wearable equipment can deliver personal healthcare and
necessary treatment remotely. One major challenge is transmitting large amount
of biosignals through wireless networks. The limited battery life calls for
low-power data compressors. Compressive Sensing (CS) has proved to be a
low-power compressor. In this study, we apply CS on the compression of
multichannel biosignals. We firstly develop an efficient CS algorithm from the
Block Sparse Bayesian Learning (BSBL) framework. It is based on a combination
of the block sparse model and multiple measurement vector model. Experiments on
real-life Fetal ECGs showed that the proposed algorithm has high fidelity and
efficiency. Implemented in hardware, the proposed algorithm was compared to a
Discrete Wavelet Transform (DWT) based algorithm, verifying the proposed one
has low power consumption and occupies less computational resources.