title: Magnetic reconnection mediated by hyper-resistive plasmoid instability

abstract:
  Magnetic reconnection mediated by the hyper-resistive plasmoid instability is
studied with both linear analysis and nonlinear simulations. The linear growth
rate is found to scale as $S_{H}^{1/6}$ with respect to the hyper-resistive
Lundquist number $S_{H}\equiv L^{3}V_{A}/\eta_{H}$, where $L$ is the system
size, $V_{A}$ is the Alfv\'en velocity, and $\eta_{H}$ is the
hyper-resistivity. In the nonlinear regime, reconnection rate becomes nearly
independent of $S_{H}$, the number of plasmoids scales as $S_{H}^{1/2}$, and
the secondary current sheet length and width both scale as $S_{H}^{-1/2}$.
These scalings are consistent with a heuristic argument assuming secondary
current sheets are close to marginal stability. The distribution of plasmoids
as a function of the enclosed flux $\psi$ is found to obey a $\psi^{-1}$ power
law over an extended range, followed by a rapid fall off for large plasmoids.
These results are compared with those from resistive magnetohydrodynamic
studies.

categories: physics.plasm-ph astro-ph.SR physics.flu-dyn physics.space-ph


title: On the chromatic number of random Cayley graphs

abstract:
  Let G be an abelian group of cardinality N, where (N,6) = 1, and let A be a
random subset of G. Form a graph Gamma_A on vertex set G by joining x to y if
and only if x + y is in A. Then, almost surely as N tends to infinity, the
chromatic number chi(Gamma_A) is at most (1 + o(1))N/2 log_2 N. This is
asymptotically sharp when G = Z/NZ, N prime.
  Presented at the conference in honour of Bela Bollobas on his 70th birthday,
Cambridge August 2013.


title:
Formulation of Non-steady-state Dust Formation Process in Astrophysical
  Environments

abstract:
  The non-steady-state formation of small clusters and the growth of grains
accompanied by chemical reactions are formulated under the consideration that
the collision of key gas species (key molecule) controls the kinetics of dust
formation process. The formula allows us to evaluate the size distribution and
condensation efficiency of dust formed in astrophysical environments. We apply
the formulation to the formation of C and MgSiO3 grains in the ejecta of
supernovae, as an example, to investigate how the non-steady effect influences
the formation process, condensation efficiency f_{con}, and average radius
a_{ave} of newly formed grains in comparison with the results calculated with
the steady-state nucleation rate. We show that the steady-state nucleation rate
is a good approximation if the collision timescale of key molecule tau_{coll}
is much smaller than the timescale tau_{sat} with which the supersaturation
ratio increases; otherwise the effect of the non-steady state becomes
remarkable, leading to a lower f_{con} and a larger a_{ave}. Examining the
results of calculations, we reveal that the steady-state nucleation rate is
applicable if the cooling gas satisfies Lambda = tau_{sat}/tau_{coll} > 30
during the formation of dust, and find that f_{con} and a_{ave} are uniquely
determined by Lambda_{on} at the onset time t_{on} of dust formation. The
approximation formulae for f_{con} and a_{ave} as a function of Lambda_{on}
could be useful in estimating the mass and typical size of newly formed grains
from observed or model-predicted physical properties not only in supernova
ejecta but also in mass-loss winds from evolved stars.


title: Colloidal Shape Effects in Evaporating Drops

abstract:
  We explore the influence of particle shape on the behavior of evaporating
drops. A first set of experiments discovered that particle shape modifies
particle deposition after drying. For sessile drops, spheres are deposited in a
ring-like stain, while ellipsoids are deposited uniformly. Experiments
elucidate the kinetics of ellipsoids and spheres at the drop's edge. A second
set of experiments examined evaporating drops confined between glass plates. In
this case, colloidal particles coat the ribbon-like air-water interface,
forming colloidal monolayer membranes (CMMs). As particle anisotropy increases,
CMM bending rigidity was found to increase, which in turn introduces a new
mechanism that produces a uniform deposition of ellipsoids and a heterogeneous
deposition of spheres after drying. A final set of experiments investigates the
effect of surfactants in evaporating drops. The radially outward flow that
pushes particles to the drop's edge also pushes surfactants to the drop's edge,
which leads to a radially inward flow on the drop surface. The presence of
radially outward flows in the bulk fluid and radially inward flows at the drop
surface creates a Marangoni eddy, among other effects, which also modifies
deposition after drying.


title: Non-equilibrium, stochastic model for tRNA binding time statistics

abstract:
  Protein translation is one of the most important processes in cell life but,
despite being well understood biochemically, the implications of its intrinsic
stochastic nature have not been fully elucidated. In this paper we develop a
microscopic and stochastic model which describes a crucial step in protein
translation, namely the binding of the tRNA to the ribosome. Our model
explicitly takes into consideration tRNA recharging dynamics, spatial
inhomogeneity and stochastic fluctuations in the number of charged tRNAs around
the ribosome. By analyzing this non-equilibrium system we are able to derive
the statistical distribution of the times needed by the tRNAs to bind to the
ribosome, and to show that it deviates from an exponential due to the coupling
between the fluctuations of charged and uncharged populations of tRNA.


title:
A Non-Alternating Algorithm for Joint BS-RS Precoding Design in Two-Way
  Relay Systems

abstract:
  Cooperative relay systems have become an active area of research during
recent years since they help cellular networks to enhance data rate and
coverage. In this paper we develop a method to jointly optimize precoding
matrices for amplify-and-forward relay station and base station. Our objective
is to increase max-min SINR fairness within co-channel users in a cell. The
main achievement of this work is avoiding any tedious alternating optimization
for joint design of RS/BS precoders, in order to save complexity. Moreover, no
convex solver is required in this method. RS precoding is done by transforming
the underlying non-convex problem into a system of nonlinear equations which is
then solved using Levenberg-Marquardt algorithm. This method for RS precoder
design is guaranteed to converge to a local optimum. For the BS precoder a
low-complexity iterative method is proposed. The efficiency of the joint
optimization method is verified by simulations.


title: Fermionic greybody factors in dilaton black holes

abstract:
  In this paper the question of emission of fermions in the process of dilaton
black hole evolution and its characters for different dilaton coupling
constants $\alpha$ is studied. The main quantity of interest, the greybody
factors are calculated both numerically and in analytical approximation. The
dependence of rates of evaporation and behaviour on the dilaton coupling
constant is analyzed. Having calculated the greybody factors we are able to
address the question of the final fate of the dilaton black hole. For that we
also need to make dynamical treatment of the solution by considering the
backreaction which will show a crucial effect on the final result. We find a
transition line in $(Q/M, \alpha)$ plane that separates the two regimes for the
fate of the black hole, decay regime and extremal regime. In the decay regime
the black hole completely evaporates, while in the extremal regime the black
hole approaches the extremal limit by radiation and becomes stable.


title: n-fold filters in residuated lattice

abstract:
  Residuated lattices play an important role in the study of fuzzy logic based
of t-norm. In this paper, we introduced the notions of n-fold implicative
filters, n-fold positive implicative filters, n-fold boolean filters, n-fold
fantastic filters, n-fold normal filters and n-fold obstinate filters in
residuated lattices and study the relations among them. This generalized the
similar existing results in BL-algebra with the connection of the work of Kerre
and all in [14], Kondo and all in [7], [11] and Motamed and all in [9]. At the
end of this paper, we draw two diagrams; the first one describe the relations
between some type of n-fold filters in residuated lattices and the second one
describe the relations between some type of n-fold residuated lattices.


title:
Higgs windows to new physics through d = 6 operators: Constraints and
  one-loop anomalous dimensions

abstract:
  The leading contributions from heavy new physics to Higgs processes can be
captured in a model-independent way by dimension-six operators in an effective
Lagrangian approach. We present a complete analysis of how these contributions
affect Higgs couplings. Under certain well-motivated assumptions, we find that
8 CP-even plus 3 CP-odd Wilson coefficients parametrize the main impact in
Higgs physics, as all other coefficients are constrained by non-Higgs SM
measurements. We calculate the most relevant anomalous dimensions for these
Wilson coefficients, which describe operator mixing from the heavy scale down
to the electroweak scale. This allows us to find the leading-log corrections to
the predictions for the Higgs couplings in specific models, such as the MSSM or
composite Higgs, which we find to be significant in certain cases.


title:
Weak Coupling BCS-like Superconductivity in the Pnictide Oxide
  Ba$_{1-x}$Na$_x$Ti$_2$Sb$_2$O (x=0 and 0.15)

abstract:
  We report the results of low-temperature heat capacity measurements of the
pnictide oxide superconductor BaTi$_2$Sb$_2$O doped with sodium. The
temperature and field dependent heat capacity data are well described by a
single-gap BCS theory. The estimated values for the normal state Sommerfeld
constant, the heat capacity jump at $T_c$, and the electron-phonon coupling
constant are in favor of a conventional weak coupling superconductivity
mediated by electron-phonon interaction. The results are discussed with regard
to and compared with recent first principle calculations.


title:
Finite-Size Effects on Return Interval Distributions for
  Weakest-Link-Scaling Systems

abstract:
  The Weibull distribution is a commonly used model for the strength of brittle
materials and earthquake return intervals. Deviations from Weibull scaling,
however, have been observed in earthquake return intervals and in the fracture
strength of quasi-brittle materials. We investigate weakest-link scaling in
finite-size systems and deviations of empirical return interval distributions
from the Weibull distribution function. We use the ansatz that the survival
probability function of a system with complex interactions among its units can
be expressed as the product of the survival probability functions for an
ensemble of representative volume elements (RVEs). We show that if the system
comprises a finite number of RVEs, it obeys the $\kappa$-Weibull distribution.
We conduct statistical analysis of experimental data and simulations that show
good agreement with the $\kappa$-Weibull distribution. We show the following:
(1) The weakest-link theory for finite-size systems involves the
$\kappa$-Weibull distribution. (2) The power-law decline of the
$\kappa$-Weibull upper tail can explain deviations from the Weibull scaling
observed in return interval data. (3) The hazard rate function of the
$\kappa$-Weibull distribution decreases linearly after a waiting time $\tau_c
\propto n^{1/m}$, where $m$ is the Weibull modulus and $n$ is the system size
in terms of representative volume elements. (4) The $\kappa$-Weibull provides
competitive fits to the return interval distributions of seismic data and of
avalanches in a fiber bundle model. In conclusion, using theoretical and
statistical analysis of real and simulated data, we show that the
$\kappa$-Weibull distribution is a useful model for extreme-event return
intervals in finite-size systems.


title: Spin filtering in nanowire directional coupler

abstract:
  The spin transport characteristics of a nanowire directional electronic
coupler have been evaluated theoretically via a transfer matrix approach. The
application of a gate field in the region of mixing allows for control of spin
current through the different leads of the coupler via the Rashba spin-orbit
interaction. The combination of spin-orbit interaction and applied gate
voltages on different legs of the coupler give rise to a controllable
modulation of the spin polarization. Both structural factors and field strength
tuning lead to a rich phenomenology that could be exploited in spintronic
devices.


title:
Nested particle filters for online parameter estimation in discrete-time
  state-space Markov models

abstract:
  We address the problem of approximating the posterior probability
distribution of the fixed parameters of a state-space dynamical system using a
sequential Monte Carlo method. The proposed approach relies on a nested
structure that employs two layers of particle filters to approximate the
posterior probability measure of the static parameters and the dynamic state
variables of the system of interest, in a vein similar to the recent
"sequential Monte Carlo square" (SMC$^2$) algorithm. However, unlike the
SMC$^2$ scheme, the proposed technique operates in a purely recursive manner.
In particular, the computational complexity of the recursive steps of the
method introduced herein is constant over time. We analyse the approximation of
integrals of real bounded functions with respect to the posterior distribution
of the system parameters computed via the proposed scheme. As a result, we
prove, under regularity assumptions, that the approximation errors vanish
asymptotically in $L_p$ ($p \ge 1$) with convergence rate proportional to
$\frac{1}{\sqrt{N}} + \frac{1}{\sqrt{M}}$, where $N$ is the number of Monte
Carlo samples in the parameter space and $N\times M$ is the number of samples
in the state space. This result also holds for the approximation of the joint
posterior distribution of the parameters and the state variables. We discuss
the relationship between the SMC$^2$ algorithm and the new recursive method and
present a simple example in order to illustrate some of the theoretical
findings with computer simulations.


title:
Time variation of the O/H radial gradient in the galactic disk based on
  planetary nebulae

abstract:
  The controversy on the time variation of the radial abundance gradients can
in principle be settled by estimating the gradients from planetary nebulae (PN)
ejected by central stars (CSPN) with different ages. In this work, we consider
four samples of CSPN whose lifetimes have been estimated using three different
methods and estimate the oxygen abundance gradients for these objects. The
results suggest some small differences between the younger and older CSPN. The
younger objects have similar or slightly higher oxygen abundances compared with
the older objects, and the gradients of both groups are similar within the
uncertainties. Therefore, the O/H radial gradient has not changed appreciably
during the lifetime of the objects considered, so that PN gradients are not
expected to be very different from the gradients observed in younger objects,
which seems to be supported by recent observational data.


title: Magneto-Transport Properties of Single Crystalline LaFeAsO

abstract:
  Measurements of magnetization, specific heat, electrical resistivity, Hall
effect, and magnetoresistance on single crystalline samples of LaFeAsO grown in
a NaAs flux are reported. While this material is known to be a semimetal, the
temperature dependence of the electrical resistivity data presented herein is
reminiscent of semiconducting behavior and exhibits distinct features
associated with a structural transition and spin density wave (SDW) order.
Magnetoresistance and Hall coefficient measurements were performed in magnetic
fields up to 9 T applied perpendicular to the basal plane using a van der Pauw
configuration. The charge carrier density and mobility indicate that electrons
are the majority charge carriers and exhibit features indicative of the
structural transition and SDW formation. Low temperature X-ray diffraction
measurements have confirmed that the structural transition in these samples
occurs near 140 K, compared to a transition temperature of 156 K observed in
polycrystalline samples. Isotherms of magnetoresistivity measured as a function
of magnetic field can be scaled onto a single curve in which the scaling field
is a linear function of temperature between 2.2 K and 180 K.


title: Characterizations for fractional Hardy inequality

abstract:
  We provide a Maz'ya type characterization for a fractional Hardy inequality.
As an application, we show that a bounded open set $G$ admits a fractional
Hardy inequality if and only if the associated fractional capacity is
quasiadditive with respect to Whitney cubes of $G$ and the zero extension
operator acting on $C_c(G)$ is bounded in an appropriate manner.


title: Comparing cost and performance of replication and erasure coding

abstract:
  Data storage systems are more reliable than their individual components. In
order to build highly reliable systems out of less reliable parts, systems
introduce redundancy. In replicated systems, objects are simply copied several
times with each copy residing on a different physical device. While such an
approach is simple and direct, more elaborate approaches such as erasure coding
can achieve equivalent levels of data protection while using less redundancy.
This report examines the trade-offs in cost and performance between replicated
and erasure encoded storage systems.


title: Strand-Based Approach to Patch Security Protocols

abstract:
  In this paper, we introduce a mechanism that aims to speed up the development
cycle of security protocols, by adding automated aid for diagnosis and repair.
Our mechanism relies on existing verification tools analyzing intermediate
protocols and synthesizing potential attacks if the protocol is flawed. The
analysis of these attacks (including type flaw attacks) pinpoints the source of
the failure and controls the synthesis of appropriate patches to the protocol.
Using strand spaces, we have developed general guidelines for protocol repair,
and captured them into formal requirements on (sets of) protocol steps. For
each requirement, there is a collection of rules that transform a set of
protocol steps violating the requirement into a set conforming it. We have
implemented our mechanism into a tool, called SHRIMP. We have successfully
tested SHRIMP on numerous faulty protocols, all of which were successfully
repaired, fully automatically.


title: SOSOPT: A Toolbox for Polynomial Optimization

abstract:
  SOSOPT is a Matlab toolbox for formulating and solving Sum-of-Squares (SOS)
polynomial optimizations. This document briefly describes the use and
functionality of this toolbox. Section 1 introduces the problem formulations
for SOS tests, SOS feasibility problems, SOS optimizations, and generalized SOS
problems. Section 2 reviews the SOSOPT toolbox for solving these optimizations.
This section includes information on toolbox installation, formulating
constraints, solving SOS optimizations, and setting optimization options.
Finally, Section 3 briefly reviews the connections between SOS optimizations
and semidefinite programs (SDPs). It is the connection to SDPs that enables SOS
optimizations to be solved in an efficient manner


title: On lattice cohomology and left-orderability

abstract:
  It has been recently conjectured by Boyer-Gordon-Watson that a closed,
orientable, irreducible $3$-manifold $M$ is a Heegaard Floer $L$-space if and
only if $\pi_1(M)$ is not left-orderable. In this article, we study this
conjecture from the point of view of lattice cohomology, an invariant
introduced by N\'emethi which is conjecturally isomorphic to the $HF^+$ version
of Heegaard Floer homology. Using the invariant's combinatorial tractability as
a stepping stone, we produce some interesting quite general families of
negative-definite graph manifolds against which to test the Boyer-Gordon-Watson
conjecture. Then, using horizontal foliation arguments and direct manipulation
of the fundamental group, we prove that these families do indeed satisfy the
conjecture.


title:
Kinematics and excitation of the nuclear spiral in the active galaxy Arp
  102B

abstract:
  We present a two-dimensional analysis of the gaseous excitation and
kinematics of the inner 2.5 x 1.7 kpc^2 of the LINER/Seyfert 1 galaxy Arp 102B,
from optical spectra obtained with the GMOS integral field spectrograph on the
Gemini North telescope at a spatial resolution of 250 pc. Emission-line flux
maps show the same two-armed nuclear spiral we have discovered in previous
observations with the HST-ACS camera. One arm reaches 1 kpc to the east and the
other 500 pc to the west, with a 8.4 GHz VLA bent radio jet correlating with
the former. The gas density is highest (500 - 900 cm^(-3)) at the nucleus and
in the northern border of the east arm, at a region where the radio jet seems
to be deflected. Channel maps show blueshifts but also some redshifts at the
eastern arm and jet location which can be interpreted as originated in the
front and back walls of an outflow pushed by the radio jet, suggesting also
that the outflow is launched close to the plane of the sky. We estimate a mass
outflow rate along the east arm of 0.26 - 0.32 Msun yr^(-1) (depending on the
assumed outflow geometry), which is between one and two orders of magnitude
higher than the mass accretion rate to the active nucleus, implying that there
is mass-loading of the nuclear outflow from circumnuclear gas. The power of
this outflow is 0.06 - 0.3%Lbol. We propose a scenario in which gas has been
recently captured by Arp 102B in an interaction with Arp 102A, settling in a
disk rotating around the nucleus of Arp 102B and triggering its nuclear
activity. A nuclear jet is pushing the circumnuclear gas, giving origin to the
nuclear arms. A blueshifted emitting gas knot is observed at 300 pc south-east
from the nucleus and can be interpreted as another (more compact) outflow, with
a possible counterpart to the north-west.


title: Categoricity in Quasiminimal Pregeometry Classes

abstract:
  Quasiminimal pregeometry classes were introduces by Zilber [2005a] to isolate
the model theoretical core of several interesting examples. He proves that a
quasiminimal pregeometry class satisfying an additional axiom, called
excellence, is categorical in all uncountable cardinalities. Recently Bays et
al. [2014] showed that excellence follows from the rest of axioms. In this
paper we present a direct proof of the categoricity result without using
excellence.


title:
Paley-Wiener-Schwartz nearly Parseval frames and Besov spaces on
  noncompact symmetric spaces

abstract:
  Let $X$ be a symmetric space of the noncompact type. The goal of the paper is
to construct in the space $L_{2}(X)$ nearly Parseval frames consisting of
functions which simultaneously belong to Paley-Wiener spaces and to Schwartz
space on $X$. We call them Paley-Wiener-Schwartz frames in $L_{2}(X)$. These
frames are used to characterize a family of Besov spaces on $X$. As a part of
our construction we develop on $X$ the so-called average Shannon-type sampling.


title:
Effects of Edge Oxidation on the Structural, Electronic, and Magnetic
  Properties of Zigzag Boron Nitride Nanoribbons

abstract:
  The effects of edge chemistry on the relative stability and electronic
properties of zigzag boron nitride nanoribbons (ZBNNRs) are investigated. Among
all functional groups considered, fully hydroxylated ZBNNRs are found to be the
most energetically stable. When an in-plane external electric field is applied
perpendicular to the axis of both hydrogenated and hydroxylated ZBNNRs, a
spin-polarized half-metallic state is induced, whose character is different
than that predicted for ZGNRs. The onset field for achieving the half-metallic
state is found to mainly depend on the width of the ribbon. Our results
indicate that edge functionalization of ZBNNRs may open the way for the design
of new nano-electronic and nano-spintronic devices.

categories: cond-mat.mtrl-sci cond-mat.mes-hall physics.chem-ph physics.comp-ph


title:
The Unfolding of the Spectra of Low Energy Galactic Cosmic Ray H and He
  Nuclei as the Voyager 1 Spacecraft Exits the Region of Heliospheric
  Modulation

abstract:
  This paper describes the unfolding of the solar modulated galactic cosmic ray
H and He nuclei spectra beyond ~105 AU in the heliosheath. Between 2008.0 and
2012.3 when Voyager 1 went from about 105 to 120.5 AU the spectral intensities
of these two components between about 30 and 500 MeV/nuc unfolded (increased)
in a manner consistent with an average modulation potential decrease ~5 MV per
AU as described by a Parker like cosmic ray transport in the heliosphere where
the overall modulation is described by a modulation potential in MV. Between
120.5 and 121.7 AU, however, as a result of two sudden intensity increases
starting on May 8th and August 25th, 2012, this modulation potential decreased
by ~80 MV and spectra resembling possible local interstellar spectra for H and
He were revealed. Considering these spectra to be the local interstellar
spectra would imply that almost 1/3 of the total modulation potential of about
270 MV required to explain the spectra of these components observed at the
Earth must occur in just a 1 AU radial interval in the outer heliosheath. As a
result about ~80% of the total modulation potential observed at the Earth at
this time occurs in the heliosheath itself. The remaining 20% of the total
modulation occurs inside the heliospheric termination shock. The details of
these intensity changes and their description by a simple modulation model are
discussed.


title:
Dynamical compactification in Einstein-Gauss-Bonnet gravity from
  geometric frustration

abstract:
  In this paper we study dynamical compactification in Einstein-Gauss-Bonnet
gravity from arbitrary dimension for generic values of the coupling constants.
We showed that, when the curvature of the extra dimensional space is negative,
for any value of the spatial curvature of the four dimensional space-time one
obtains a realistic behavior in which for asymptotic time both the volume of
the extra dimension and expansion rate of the four dimensional space-time tend
to a constant. Remarkably, this scenario appears within the open region of
parameters space for which the theory does not admit any maximally symmetric
(4+D)- dimensional solution, which gives to the dynamical compactification an
interpretation as geometric frustration. In particular there is no need to
fine-tune the coupling constants of the theory so that the present scenario
does not violate "naturalness hypothesis". Moreover we showed that with
increase of the number of extra dimensions the stability properties of the
solution are increased.


title:
On the Moore-Penrose inverse, EP Banach space operators and EP Banach
  algebra elements

abstract:
  The main concern of this note is the Moore-Penrose inverse in the context of
Banach spaces and algebras. Especially attention will be given to a particular
class of elements with the aforementioned inverse, namely EP Banach space
operators and Banach algebra elements, which will be studied and characterized
extending well-known results obtained in the frame of Hilbert space operators
and $C^*$-algebra elements.


title: The non-Abelian Weyl-Yang-Kaluza-Klein gravity model

abstract:
  The Weyl$-$Yang gravitational gauge theory is investigated in the structure
of a pure higher-dimensional non-Abelian Kaluza$-$Klein background. We
construct the dimensionally reduced field equations and stress-energy-momentum
tensors as well as the four dimensional modified Weyl$-$Yang$+$Yang$-$Mills
theory from an arbitrary curved $internal$ space in the anholonomic frame which
are the extensions of our previous model for the non-Abelian case. In
particular, the coset space reduction is considered to explicitly obtain the
interactions between the gravitational and the gauge fields. The resulting
equations not only appear to be generalization of the well-established
equations of non-Abelian theory but also contain intrinsically the generalized
gravitational source term which does not exist in the literature so far and the
Yang$-$Mills force density which is exactly equivalent to the negative gradient
of a Yang$-$Mills quadratic invariant.


title: Small maximal partial ovoids in generalized quadrangles

abstract:
  A {\em maximal partial ovoid} of a generalized quadrangle is a maximal set of
points no two of which are collinear. The problem of determining the smallest
size of a maximal partial ovoid in quadrangles has been extensively studied in
the literature. In general, theoretical lower bounds on the size of a maximal
partial ovoid in a quadrangle of order $(s,t)$ are linear in $s$. In this
paper, in a wide class of quadrangles of order $(s,t)$ we give a construction
of a maximal partial ovoid of size at most $s \cdot \mbox{polylog}(s)$, which
is within a polylogarithmic factor of theoretical lower bounds. The
construction substantially improves previous quadratic upper bounds in
quadrangles of order $(s,s^2)$, in particular in the well-studied case of the
elliptic quadrics $Q^-(5,s)$.


title: Hypothesis testing for stochastic PDEs driven by additive noise

abstract:
  We study the simple hypothesis testing problem for the drift coefficient for
stochastic fractional heat equation driven by additive noise. We introduce the
notion of asymptotically the most powerful test, and find explicit forms of
such tests in two asymptotic regimes: large time asymptotics, and increasing
number of Fourier modes. The proposed statistics are derived based on Maximum
Likelihood Ratio. Additionally, we obtain a series of important technical
results of independent interest: we find the cumulant generating function of
the log-likelihood ratio; obtain sharp large deviation type results for
$T\to\infty$ and $N\to\infty$.


title:
Distributed Object Store Principles of Operation The Case for
  Intelligent Storage

abstract:
  In this paper we look at the growth of distributed object stores (DOS) and
examine the underlying mechanisms that guide their use and development. Our
focus is on the fundamental principles of operation that define this class of
system, how it has evolved, and where it is heading as new markets expand
beyond the use originally presented. We conclude by speculating about how
object stores as a class must evolve to meet the more demanding requirements of
future applications.


title: Vertical broad-line region structure in nearby active galactic nuclei

abstract:
  Broad emission lines are emitted in the surroundings of supermassive black
holes in the centers of active galactic nuclei (AGN). This region is spatially
not resolved. We intend to get information on the structure and geometry of
this broad emitting line region (BLR) based on line profile observations. We
model the rotational and turbulent velocities in the line-emitting regions
based on observed full-width at half maximum line values (FWHM) and
{\sigma}_{line} of the variable broad emission lines in four nearby AGN: NGC
3783, NGC 7469, NGC 5548, and 3C 390.3. On the basis of these velocities, we
estimate the height of the line-emitting regions above the midplane in context
with their distances from the center. The H{\beta} lines are emitted in a more
flattened configuration above the midplane in comparison to the highly ionized
lines. The H{\beta} lines originate at heights of 0.7 to 1.6 light-days and at
distances of 1.4 to 24 light-days with height/distance (H/R) ratios of only
0.07 to 0.5. The highly ionized lines originate at smaller radii than the
H{\beta} lines and/or at greater distances above the midplane with H/R values
of 0.2 to 1.7. In total, the emission lines do not originate in a thin
atmosphere of an accretion disk but rather at very extended regions above an
accretion disk. The observed geometries of the line-emitting regions resemble
the geometries of accretion disk wind models. Furthermore, the angle of the
central opening cone (generated by the emitting regions of the highly ionized
lines) is small for those galaxies with slow rotational velocities and
increases with the rotation velocity of the central region. The derived
geometries of the line-emitting regions of all four AGN are consistent with the
geometries that are predicted in outflowing disk wind models.


title:
Generalized Wilson Chain for solving multichannel quantum impurity
  problems

abstract:
  The Numerical Renormalization Group is used to solve quantum impurity
problems, which describe magnetic impurities in metals, nanodevices, and
correlated materials within DMFT. Here we present a simple generalization of
the Wilson Chain, which improves the scaling of computational cost with the
number of channels/bands, bringing new problems within reach. The method is
applied to calculate the t-matrix of the three-channel Kondo model at T=0,
which shows universal crossovers near non-Fermi liquid critical points. A
non-integrable three-impurity problem with three bands is also studied,
revealing a rich phase diagram and novel screening/overscreening mechanisms.


title:
ASCOT: solving the kinetic equation of minority particle species in
  tokamak plasmas

abstract:
  A comprehensive description of methods, suitable for solving the kinetic
equation for fast ions and impurity species in tokamak plasmas using Monte
Carlo approach, is presented. The described methods include Hamiltonian
orbit-following in particle and guiding center phase space, test particle or
guiding center solution of the kinetic equation applying stochastic
differential equations in the presence of Coulomb collisions, neoclassical
tearing modes and Alfv\'en eigenmodes as electromagnetic perturbations relevant
to fast ions, together with plasma flow and atomic reactions relevant to
impurity studies. Applying the methods, a complete reimplementation of the
well-established minority species code ASCOT is carried out as a response both
to the increase in computing power during the last twenty years and to the
weakly structured growth of the code, which has made implementation of
additional models impractical. Also, a benchmark between the previous code and
the reimplementation is accomplished, showing good agreement between the codes.


title:
A Numerical Method for the Two Layer Shallow Water Equations with Dry
  States

abstract:
  A numerical method is proposed for solving the two layer shallow water
equations with variable bathymetry in one dimension based on high-resolution
f-wave-propagation finite volume methods. The method splits the jump in the
fluxes and source terms into waves propagating away from each grid cell
interface. It addresses the required determination of the system's
eigenstructure and a scheme for evaluating the flux and source terms. It also
handles dry states in the system where the bottom layer depth becomes zero,
utilizing existing methods for the single layer solution and handling single
layer dry states that can exist independently. Sample results are shown
illustrating the method and its handling of dry states including an idealized
ocean setting.


title: Inflation induced by Gravitino Condensation in Supergravity

abstract:
  We discuss the emergence of an inflationary phase in supergravity with the
super-Higgs effect due to dynamical spontaneous breaking of supersymmetry, in
which the role of the inflaton is played by the gravitino condensate. Realistic
models compatible with the Planck satellite CMB data are found in conformal
supergravity scenarios with dynamical gravitino masses that are small compared
to the Planck mass, as could be induced by a non-trivial vacuum expectation
value of the dilaton superfield of appropriate magnitude.


title:
The influence of spin fluctuations on the thermal conductivity in
  superconducting Ba(Fe_{1-x}Co_x)_2As_2

abstract:
  The thermal conductivity of electron-doped Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$
single crystals is investigated below 200K, with an emphasis on the behavior
near the magnetic and superconducting (T_c) transition temperatures. An
enhancement of the in-plane thermal conductivity $\kappa_{ab}$ is observed
below T_c for all samples, with the greatest enhancement observed near optimal
doping. The observed trends are consistent with the scattering of heat carriers
by low-energy magnetic excitations. Upon entering the superconducting state,
the formation of a spin-gap leads to reduced scattering and an enhancement in
$\kappa(T)$. Similarly, an enhancement of $\kappa$ is observed for
polycrystalline BaFe2As2 below the magnetic transition, and qualitative
differences in $\kappa(T)$ between single crystalline and polycrystalline
BaFe2As2 are utilized to discuss anisotropic scattering. This study highlights
how measuring $\kappa$ near $T_c$ in novel superconductors can be useful as a
means to probe the potential role of spin fluctuations.


title:
A New Approach to Developing Interactive Software Modules through
  Graduate Education

abstract:
  Educational technology has attained significant importance as a mechanism for
supporting experiential learning of science concepts. However, the growth of
this mechanism is limited by the significant time and technical expertise
needed to develop such products, particularly in specialized fields of science.
We sought to test whether interactive, educational, online software modules can
be developed effectively by students as a curriculum component of an advanced
science course. We discuss a set of fifteen such modules developed by Harvard
University graduate students to demonstrate various concepts related to
astronomy and physics. Their successful development of these modules
demonstrates that online software tools for education and outreach on
specialized topics can be produced while simultaneously fulfilling
project-based learning objectives. We describe a set of technologies suitable
for module development and present in detail four examples of modules developed
by the students. We offer recommendations for incorporating educational
software development within a graduate curriculum and conclude by discussing
the relevance of this novel approach to new online learning environments like
edX


title: Phase space analysis of semilinear parabolic equations

abstract:
  We present a wave packet analysis of a class of possibly degenerate parabolic
equations with variable coefficients. As a consequence, we prove local
wellposedness of the corresponding Cauchy problem in spaces of low regularity,
namely the modulation spaces, assuming a nonlinearity of analytic type. As
another application, we deduce that the corresponding phase space flow
decreases the global wave front set. We also consider the action on spaces of
analytic functions, provided the coefficients are analytic themselves.


title:
Number of information and its relation to the cosmological constant
  resulting from Landauer's principle

abstract:
  Using a recent published formula for the number of information N that results
from Landauer's principle we obtain an expression for the cosmological constant
Lambda. Next, assuming the universe as a system of mass M satisfying Landauer's
principle and eliminating its mass M from the given expression for the number
of information, we obtain a new expression that agrees with the one derived by
Lloyd. Furthermore, we modify the generalized entropy relation and three
equivalent entropy expressions are obtained. Finally, in two different
universes the time rate of change of the entropy is calculated. In a flat
universe the time rate of the entropy is time independent and depends on
fundamental constants of physics.


title: Social optimum in Social Groups with Give-and-Take criterion

abstract:
  We consider a "Social Group" of networked nodes, seeking a "universe" of
segments. Each node has subset of the universe, and access to an expensive
resource for downloading data. Alternatively, nodes can also acquire the
universe by exchanging segments among themselves, at low cost, using a local
network interface. While local exchanges ensure minimum cost, "free riders" in
the group can exploit the system. To prohibit free riding, we propose the
"Give-and-Take" criterion, where exchange is allowed if each node has segments
unavailable with the other. Under this criterion, we consider the problem of
maximizing the aggregate cardinality of the nodes' segment sets. First, we
present a randomized algorithm, whose analysis yields a lower bound on the
expected aggregate cardinality, as well as an approximation ratio of 1/4 under
some conditions. Four other algorithms are presented and analyzed. We identify
conditions under which some of these algorithms are optimal


title:
On the analysis of the Illumina 450K array data: probes ambiguously
  mapped to the human genome

abstract:
  We pointed out that a substantial number of CpG probes on the Illumina 450K
array could be mapped to multiple loci across the human genome. These CpGs need
to be considered when interpreting results using this platform.


title:
T-duality through BV Morphisms and BV Pushforwards in Topological Field
  Theories

abstract:
  We introduce the concept of duality between quantum field theories in the
Batalin-Vilkovisky formalism, which is interpreted either as a BV morphism, the
result of dual BV pushforwards or a combination of both. When a BV morphism
affects only the target space of a given model, we call it T-duality. To
justify this name, we demonstrate how topological aspects of T-duality in
string theory such as the relation between curvature and H-flux or isomorphisms
of Courant algebroids are equivalent to dualities of topological sigma models
in two and three dimensions.


title:
Purifications of multipartite states: limitations and constructive
  methods

abstract:
  We analyze the description of quantum many-body mixed states using matrix
product states and operators. We consider two such descriptions: (i) as a
matrix product density operator of bond dimension D, and (ii) as a purification
that is written as a matrix product state of bond dimension D'. We show that
these descriptions are inequivalent in the sense that D' cannot be upper
bounded by D only. Then we provide two constructive methods to obtain (ii) out
of (i). The sum of squares (sos) polynomial method scales exponentially in the
number of different eigenvalues, and its approximate version is formulated as a
Semidefinite Program, which gives efficient approximate purifications whose D'
only depends on D. The eigenbasis method scales quadratically in the number of
eigenvalues, and its approximate version is very efficient for rapidly decaying
distributions of eigenvalues. Our results imply that a description of mixed
states which is both efficient and locally positive semidefinite does not
exist, but that good approximations do.

categories: quant-ph cond-mat.str-el math-ph math.MP


title:
What do the Star Formation Histories of Galaxies tell us about the
  Starburst-AGN connection?

abstract:
  Using a sample of 229618 narrow emission-line galaxies, we have determined
the normal star formation histories (SFHs) for galaxies with different activity
types: star forming galaxies (SFGs), transition type objects (TOs), Seyfert 2s
(Sy2s) and LINERs. We find that the variation of the SFH with the activity type
is explained by the mass of the galaxies and the importance of their bulge: the
LINERs reside in massive early-type galaxies, the Sy2s and TOs are hosted by
intermediate mass galaxies with intermediate morphological types, and the SFGs
are found in lower mass late-type spirals. Except for the Sy2s, the more
massive galaxies formed the bulk of their stars more rapidly than the less
massive ones. The Sy2s formed their stars more slowly and show presently an
excess in star formation. We have also found that the maximum in star formation
rate in the past increases with the virial mass within the aperture (VMA), the
VMA increasing from the SFGs to the TOs, to the Sy2s, culminating in the
LINERs. This correlation suggests that the bulges and the supermassive black
holes at the center of galaxies grow in parallel, in good agreement with the
M(BH)-sigma relation.


title: Universal behavior beyond multifractality in quantum many-body systems

abstract:
  How many states of a configuration space contribute to a wave-function?
Attempts to answer this ubiquitous question have a long history in physics and
chemistry, and are keys to understand e.g. localization phenomena. Quantifying
this aspect has often been overlooked for interacting many-body quantum
systems, mainly due to the exponential growth of the configuration (Hilbert)
space. Here, we introduce two Monte Carlo schemes to calculate Shannon-Renyi
entropies for ground-states of large quantum many-body systems that are out of
reach for any other exact method. Our simulations reveal that the very nature
of quantum phases of matter and associated transitions is captured by universal
subleading terms in these entropies, on top of a generic dominant multifractal
behavior.


title: Entropy of a Rindler Observer

abstract:
  We compute the entropy of a Rindler particle-detector (observer) in the
presence of a quantum field in the Minkowski vacuum state; due to the Unruh
effect, the observer is immersed in a thermal bath at a temperature
proportional to its proper acceleration.


title: Slope evolution of GRB correlations and cosmology

abstract:
  Gamma -ray bursts (GRBs) observed up to redshifts $z>9.4$ can be used as
possible probes to test cosmological models. Here we show how changes of the
slope of the {\it luminosity $L^*_X$ -break time $T^*_a$} correlation in GRB
afterglows, hereafter the LT correlation, affect the determination of the
cosmological parameters. With a simulated data set of 101 GRBs with a central
value of the correlation slope that differs on the intrinsic one by a $5\sigma$
factor, we find an overstimated value of the matter density parameter,
$\Omega_M$, compared to the value obtained with SNe Ia, while the Hubble
constant, $H_0$, best fit value is still compatible in 1$\sigma$ compared to
other probes. We show that this compatibility of $H_0$ is due to the large
intrinsic scatter associated with the simulated sample. Instead, if we consider
a subsample of high luminous GRBs ($HighL$), we find that both the evaluation
of $H_0$ and $\Omega_M$ are not more compatible in 1$\sigma$ and $\Omega_M$ is
underestimated by the $13\%$. However, the $HighL$ sample choice reduces
dramatically the intrinsic scatter of the correlation, thus possibly
identifying this sample as the standard canonical `GRBs' confirming previous
results presented in Dainotti et al. (2010,2011). Here, we consider the LT
correlation as an example, but this reasoning can be extended also for all
other GRB correlations. In literature so far GRB correlations are not corrected
for redshift evolution and selection biases, therefore we are not aware of
their intrinsic slopes and consequently how far the use of the observed
correlations can influence the derived `best' cosmological settings. Therefore,
we conclude that any approach that involves cosmology should take into
consideration only intrinsic correlations not the observed ones.


title:
Quantum Computation in Noiseless Subsystems with Fast Non-Abelian
  Holonomies

abstract:
  Quantum information processing requires a high degree of isolation from the
detrimental effects of the environment as well as an extremely precise level of
control on the way quantum dynamics unfolds in the information-processing
system. In this paper, we show how these two goals can be ideally achieved by
hybridizing the concepts of noiseless subsystems and of holonomic quantum
computation. An all-geometric universal computation scheme based on
non-adiabatic and non-Abelian quantum holonomies embedded in a four-qubit
noiseless subsystem for general collective decoherence is proposed. The
implementation details of this synergistic scheme along with the analysis of
its stability against symmetry-breaking imperfections are presented.


title: A Dirty Holographic Superconductor

abstract:
  We study the effects of disorder on a holographic superconductor by
introducing a random chemical potential on the boundary. We consider various
realizations of disorder and find that the critical temperature for
superconductivity is enhanced. We also present evidence for a precise form of
renormalization in this system. Namely, when the random chemical potential is
characterized by a Fourier spectrum of the form $k^{-2\alpha}$ we find that the
spectra of the condensate and the charge density are again power-laws, whose
exponents are accurately and universally governed by linear functions of
$\alpha$.

categories: hep-th cond-mat.dis-nn cond-mat.supr-con gr-qc


title: Conformal Complementarity Maps

abstract:
  We study quantum cosmological models for certain classes of bang/crunch
singularities, using the duality between expanding bubbles in AdS with a FRW
interior cosmology and perturbed CFTs on de Sitter space-time. It is pointed
out that horizon complementarity in the AdS bulk geometries is realized as a
conformal transformation in the dual deformed CFT. The quantum version of this
map is described in full detail in a toy model involving conformal quantum
mechanics. In this system the complementarity map acts as an exact duality
between eternal and apocalyptic Hamiltonian evolutions. We calculate the
commutation relation between the Hamiltonians corresponding to the different
frames. It vanishes only on scale invariant states.


title:
Dynamics of self-organized driven particles with competing range
  interaction

abstract:
  Non-equilibrium self-organized patterns formed by particles interacting
through competing range interaction are driven over a substrate by an external
force. We show that, with increasing driving force, the pre-existed static
patterns evolve into dynamic patterns either via disordered phase or depinned
patterns, or via the formation of non-equilibrium stripes. Strikingly, the
stripes are formed either in the direction of the driving force or in the
transverse direction, depending on the pinning strength. The revealed dynamical
patterns are summarized in a dynamical phase diagram.


title: On the fluid behavior of a baryon rich hadron resonance gas

abstract:
  We investigate the effects of finite baryon chemical potential on the
transport properties of a hadron resonance gas. We find that a hadron resonance
gas with large baryon number density is closer to the ideal fluid limit than
the corresponding gas with zero baryon number. This suggests that the system
created at the Relativistic Heavy Ion Collider (RHIC) at lower collision
energies may behave as a fluid, with an effective fluidity close to the one
found at RHIC's highest energy near phase transition. This might explain why
the differential elliptic flow coefficient measured at lower collisional
energies at RHIC is similar to the one observed at high energies.


title: Relaxation of inverted quantum system coupled with metallic nanoobjects

abstract:
  The problems of the luminescent enhancement and life time shortening for the
inverted quantum system (QS) are analysed. The commonly accepted in
publications approach appears to be questionable from the point of view of
basic principles. An alternative approach using the well-known density matrix
formalism and kinetic equation for the electrons in the coupled nano object is
suggested.


title:
Calculation of the Autocorrelation Function of the Stochastic Single
  Machine Infinite Bus System

abstract:
  Critical slowing down (CSD) is the phenomenon in which a system recovers more
slowly from small perturbations. CSD, as evidenced by increasing signal
variance and autocorrelation, has been observed in many dynamical systems
approaching a critical transition, and thus can be a useful signal of proximity
to transition. In this paper, we derive autocorrelation functions for the state
variables of a stochastic single machine infinite bus system (SMIB). The
results show that both autocorrelation and variance increase as this system
approaches a saddle-node bifurcation. The autocorrelation functions help to
explain why CSD can be used as an indicator of proximity to criticality in
power systems revealing, for example, how nonlinearity in the SMIB system
causes these signs to appear.


title: Kernel estimates for nonautonomous Kolmogorov equations

abstract:
  Using time dependent Lyapunov functions, we prove pointwise upper bounds for
the heat kernels of some nonautonomous Kolmogorov operators with possibly
unbounded drift and diffusion coefficients.


title: Hard rods in a cylindrical pore: the nematic-to-smectic phase transition

abstract:
  The effect of cylindrical confinement on the phase behaviour of a system of
parallel hard rods is studied using Onsager's second virial theory. The hard
rods are represented as hard cylinders of diameter $D$ and length $L$, while
the cylindrical pore is infinite with diameter $W$. The interaction between the
wall and the rods is hard repulsive, and it is assumed that molecules are
parallel to the surface of the pore (planar anchoring). In very narrow pores
($D<W<2 D$), the structure is homogeneous and the system behaves as a
one-dimensional Tonks gas. For wider pores, inhomogeneous fluid structures
emerge because of the lowering of the average excluded volume due to the
wall-particle interaction. The bulk nematic-smectic A phase transition is
replaced by a transition between inhomogeneous nematic and smectic A phases.
The smectic is destabilized with respect to the nematic for decreasing pore
width; this effect becomes substantial for $W<10 D$. For $W>100 D$, results for
bulk and confined fluids agree well due to the short range effect of the wall
($\sim 3-4D$).


title: Predictions of Entropic Gravity

abstract:
  We discuss consequences of an entropic view of gravity, which differs in
details from the original proposals of Jacobson and Verlinde. We assume the
entropy is localized in the degrees of freedom of the systems interacting
gravitationally. We then find there is a density-dependent minimum length for
Newtonian gravity. This makes renormalizability issues irrelevant. It also
follows that at nanometer scales Newton's universal law fails, black holes with
mass $M_{BH} \lesssim 10^{-13} M_{\odot}$ do not exist and all Hawking
radiation is at unobservably low temperature.


title: Dirac Operators on Noncommutative Curved Spacetimes

abstract:
  We study the notion of a Dirac operator in the framework of twist-deformed
noncommutative geometry. We provide a number of well-motivated candidate
constructions and propose a minimal set of axioms that a noncommutative Dirac
operator should satisfy. These criteria turn out to be restrictive, but they do
not fix a unique construction: two of our operators generally satisfy the
axioms, and we provide an explicit example where they are inequivalent. For
highly symmetric spacetimes with Drinfeld twists constructed from sufficiently
many Killing vector fields, all of our operators coincide. For general
noncommutative curved spacetimes we find that demanding formal self-adjointness
as an additional condition singles out a preferred choice among our candidates.
Based on this noncommutative Dirac operator we construct a quantum field theory
of Dirac fields. In the last part we study noncommutative Dirac operators on
deformed Minkowski and AdS spacetimes as explicit examples.


title:
Identification of Parameters and Initial Values for Reaction-Diffusion
  Systems in Protein Networks (Extended Version)

abstract:
  Spatio-temporal biochemical signaling in a large class of protein-protein
interaction networks is well modeled by a reaction-diffusion system. The global
existence of the solution to the reaction-diffusion system is determined by the
reaction kinetics model and the protein network topology. We propose a novel
reaction kinetics model that guarantees that the reaction-diffusion system with
this model has a nonnegative invariant global classical solution for any
network topology. We then present a computational method to identify the
unknown parameters and initial values for a reaction-diffusion system with this
reaction kinetics model. The identification approach solves an optimization
problem that minimizes the cost function defined as the $L^2$-norm of the
difference between the data and the solution of the reaction-diffusion system.
We utilize an adjoint-based optimal control method to obtain the gradients of
the cost function with respect to the parameters and initial values. The
regularity of the global classical solutions of the reaction-diffusion system
and its corresponding adjoint system avoids situations in which the gradients
blow up, and therefore guarantees the success of the identification method for
any network structure. Utilizing this gradient information, an efficient
algorithm to solve the optimization problem is proposed and applied to estimate
the mass diffusivities, rate constants and initial values of a
reaction-diffusion system that models protein-protein interactions in a
signaling network that regulates the actin cytoskeleton in a malignant breast
cell.


title: The evolution of H-surfaces with a Plateau boundary condition

abstract:
  In this paper we consider the heat flow associated to the classical Plateau
problem for surfaces of prescribed mean curvature. We show that an
isoperimetric condition on H ensures the existence of a global weak solution.
Moreover, we establish that these global solutions sub-converge, as time tends
to infinity, to a conformal solution of the classical Plateau problem for
surfaces of prescribed mean curvature.


title: Proton-nucleus collisions at LHC energy in the Monte Carlo model

abstract:
  A Monte Carlo model, initially developed for soft pp and AA collisions at
high energy, is applied for proton-lead interaction at the LHC energy.
Elementary collisions are implemented at the partonic level and do not involve
the usual Glauber supposition of independent nucleon-nucleon collisions. The
average number of participating nucleons and charged multiplicity in p-Pb
collisions were calculated and compared with the predictions of Glauber model
and experimental data. It was demonstrated that taking into account the energy
conservation results in the number of participating nucleons considerably lower
than in the Glauber approach. Different ways of centrality determination in pA
are discussed and the influence of the methods of centrality definition on mean
observables and their variances is studied.


title:
Chandra Survey of Nearby Highly Inclined Disc Galaxies - II: Correlation
  Analysis of Galactic Coronal Properties

abstract:
  X-ray observations provide a key tool for exploring the properties of
galactic coronae and their formation processes. In an earlier paper, we have
presented a Chandra data analysis of the coronae of 53 nearby highly-inclined
disc galaxies. Here we study the correlation of the X-ray measurements with
other galaxy properties and compare the results with those obtained for
elliptical galaxies. A good correlation is present between the coronal
luminosity Lx and the SFR. But we find a better correlation between Lx and the
total SN mechanical energy input rate (ESN), including the expected
contribution from core collapsed (CC) and Ia SNe. The X-ray radiation
efficiency (eta=Lx/ESN) has a mean value of ~0.4% with an rms of ~0.5dex. eta
further correlates with MTF/M* (MTF is the baryon mass measured from the
rotation velocity and the Tully-Fisher relation, M* is the stellar mass
measured from the K-band luminosity) and the CC SN rate surface density (FSN,
in units of SN/yr/kpc^2), which can be characterized as: eta=0.41%MTF/M* and
eta=1.4%FSN^-0.3. These correlations reflect the roles played by the
gravitational mass and energetic feedback concentrations in determining eta.
The characteristic temperature of the corona shows little dependence on the
total or specific SFR, the cold gas content, or Lx. The coronae of disc
galaxies tend to be more X-ray luminous, hotter, and lower in Fe/O abundance
ratio than those of elliptical ones of similar masses. Early-type non-starburst
disc galaxies tend to be more Fe-rich, while starburst ones have a roughly
constant abundance ratio of Fe/O~0.36solar. Our results are consistent with the
coronal gas being mainly provided by stellar feedback in a mass range of
M*~10^{8.7-11}Msun. In addition, processes such as charge exchange at cool/hot
gas interfaces, as well as various environmental effects, are also needed to
explain the diversity of coronal properties.


title: Surface tension and contact with soft elastic solids

abstract:
  Johnson-Kendall-Robert (JKR) theory is the basis of modern contact mechanics.
It describes how two deformable objects adhere together, driven by adhesion
energy and opposed by elasticity. However, it does not include solid surface
tension, which also opposes adhesion by acting to flatten the surface of soft
solids. We tested JKR theory to see if solid surface tension affects
indentation behaviour. Using confocal microscopy, we characterised the
indentation of glass particles into soft, silicone substrates. While JKR theory
held for particles larger than a critical, elastocapillary lengthscale, it
failed for smaller particles. Instead, adhesion of small particles mimicked the
adsorption of particles at a fluid interface, with a size-independent contact
angle between the undeformed surface and the particle given by a generalised
version of Young's law. A simple theory quantitatively captures this behaviour,
and explains how solid surface tension dominates elasticity for small-scale
indentation of soft materials.


title: Sisyphus Cooling of Lithium

abstract:
  Laser cooling to sub-Doppler temperatures by optical molasses is thought to
be inhibited in atoms with unresolved, near-degenerate hyperfine structure in
the excited state. We demonstrate that such cooling is possible in one to three
dimensions, not only near the standard D2 line for laser cooling, but over a
range extending to the D1 line. Via a combination of Sisyphus cooling followed
by adiabatic expansion, we reach temperatures as low as 40 \mu K, which
corresponds to atomic velocities a factor of 2.6 above the limit imposed by a
single photon recoil. Our method requires modest laser power at a frequency
within reach of standard frequency locking methods. It is largely insensitive
to laser power, polarization and detuning, magnetic fields, and initial
hyperfine populations. Our results suggest that optical molasses should be
possible with all alkali species.


title: The white dwarf cooling sequence of the Galactic bulge

abstract:
  We collected F606W- and F814W-band time-series data of the Sagittarius
low-reddening window in the Galactic bulge with the Advanced Camera far Surveys
mounted on the Hubble Space Telescope. We sampled the region approximately
every two weeks for one year, with the principal aim to detect a hidden
population of isolated black holes and neutron stars in the Galactic disk
through astrometric microlensing. We present preliminary results here based on
a photometric catalog including ~3*10^5 stars down to F606W ~ 31 mag. Proper
motions were also measured, with an accuracy of better than ~ 0.5 mas/yr at
F606W ~ 28 mag in both coordinates. We were then able to separate disk and
bulge stars and to obtain a clean bulge color-magnitude diagram. Together with
a dozen candidate extreme horizontal branch stars we were able to identify for
the first time a clearly defined white dwarf (WD) cooling sequence in the
bulge. The comparison between theory and observations shows that a substantial
fraction of the WDs (~40%) is systematically redder than the canonical cooling
tracks for CO-core DA WDs. This evidence would suggest the presence of a
significant number of He-core WDs in the bulge, formed in close binaries, as
has been found in some Galactic globular and open clusters. The presence of
close binaries in the bulge population is further supported by the finding of a
candidate dwarf nova in outburst and a few candidate cataclysmic variables in
quiescence in the same field.


title: On preconditioners for the Laplace double-layer in 2D

abstract:
  The discretization of the double-layer potential integral equation for the
interior Dirichlet Laplace problem in a domain with smooth boundary results in
a linear system that has a bounded condition number. Thus, the number of
iterations required for the convergence of a Krylov method is, asymptotically,
independent of the discretization size $N$. Using the Fast Multipole Method
(FMM) to accelerate the matrix-vector products, we obtain an optimal
$\mathcal{O}(N)$ solver. In practice, however, when the geometry is
complicated, the number of Krylov iterations can be quite large---to the extend
that necessitates the use of preconditioning.
  We summarize the different methodologies that have appeared in the literature
(single-grid, multigrid, approximate sparse inverses) and we propose a new
class of preconditioners based on an FMM-based spatial decomposition of the
double-layer operator. We present an experimental study in which we compare the
different approaches and we discuss the merits and shortcomings of our
approach. Our method can be easily extended to other second-kind integral
equations with non-oscillatory kernels in two and three dimensions.


title: The Cancer Diaspora: Metastasis beyond the seed and soil hypothesis

abstract:
  Do cancer cells escape their confinement of their original habitat in the
primary tumor or are they forced out by ecological changes in their home niche?
Describing metastasis in terms of a simple one-way migration of cells from the
primary to target organs is an insufficient concept to cover the nuances of
cancer spread. A diaspora is the scattering of people away from an established
homeland. To date, diaspora has been a uniquely human term utilized by social
scientists, however, the application of the diaspora concept to metastasis may
yield new biological insights as well as therapeutic paradigms. The diaspora
paradigm takes into account and models several variables: the quality of the
primary tumor microenvironment, the fitness of individual cancer cell migrants
as well as migrant populations, the rate of bidirectional migration of cancer
and host cells between cancer sites, and the quality of the target
microenvironments to establish metastatic sites. Ecological scientific
principles can be applied to the cancer diaspora to develop new therapeutic
strategies. For example, ecological traps, habitats that lead to the extinction
of a species, can be developed to attract cancer cells to a place where they
can be better exposed to treatments or to cells of the immune system for
improved antigen presentation. Merging the social science concept of diaspora
with ecological and population sciences concepts can inform the cancer field to
understand the biology of tumorigenesis and metastasis and inspire new ideas
for therapy.


title:
The Effect of van der Waals interaction in Elastic Collision between
  Ps(1s) and H(1s)

abstract:
  The modified static exchange model (MSEM) recently introduced by Ray [1] to
study two-atomic collision processes at low and cold-energies, is used for
detailed analysis of the long-range effects due to induced dipole-dipole van
der Waals interaction between Ps and H atoms. The MSEM includes the
non-adiabatic short-range effect due to electron-exchange and the long-range
effect due to induced dynamic dipole polarisabilities of the atoms. The
effective interatomic potential is highly sensitive to the minimum distance
between the atoms ( ). The s-, p- and d- wave elastic phase shifts,
corresponding partial cross sections, the scattering length and effective
ranges are calculated and studied with the variation of the chosen least
interatomic distance between them. It is found that the scattering length is
highly sensitive to the effective interatomic potential that depends on the
least interatomic distance. In addition the studies are made in search of
Feshbach resonances. The observed interesting feature with the variation of in
the triplet channel invites more accurate investigations if new physics.


title:
Time series modeling with pruned multi-layer perceptron and 2-stage
  damped least-squares method

abstract:
  A Multi-Layer Perceptron (MLP) defines a family of artificial neural networks
often used in TS modeling and forecasting. Because of its "black box" aspect,
many researchers refuse to use it. Moreover, the optimization (often based on
the exhaustive approach where "all" configurations are tested) and learning
phases of this artificial intelligence tool (often based on the
Levenberg-Marquardt algorithm; LMA) are weaknesses of this approach
(exhaustively and local minima). These two tasks must be repeated depending on
the knowledge of each new problem studied, making the process, long, laborious
and not systematically robust. In this paper a pruning process is proposed.
This method allows, during the training phase, to carry out an inputs selecting
method activating (or not) inter-nodes connections in order to verify if
forecasting is improved. We propose to use iteratively the popular damped
least-squares method to activate inputs and neurons. A first pass is applied to
10% of the learning sample to determine weights significantly different from 0
and delete other. Then a classical batch process based on LMA is used with the
new MLP. The validation is done using 25 measured meteorological TS and
cross-comparing the prediction results of the classical LMA and the 2-stage
LMA.


title:
Locally equilibrated stress recovery for goal oriented error estimation
  in the extended finite element method

abstract:
  Goal oriented error estimation and adaptive procedures are essential for the
accurate and efficient evaluation of numerical simulations that involve complex
domains. By locally improving the approximation quality we can solve expensive
problems which could result intractable otherwise. Here, we present an error
estimation technique for enriched finite element approximations that is based
on an equilibrated recovery technique, which considers the stress intensity
factor as the quantity of interest. The locally equilibrated superconvergent
patch recovery is used to obtain enhanced stress fields for the primal and dual
problems defined to evaluate the error estimate.


title: Electrostatic stability and encapsidation of charged nano-droplets

abstract:
  We investigate electrostatic stability of charged droplets, modeled as
permeable, charged spheres, and their encapsidation in thin, arbitrarily
charged nano-shells, immersed in a neutralizing asymmetric electrolyte
background. The latter consists of a small concentration of mobile multivalent
counterions in a bathing solution of monovalent (positive and negative) ions.
We use extensive Monte-Carlo simulations to investigate the spatial
distribution of multivalent counterions and the electrostatic component of
their osmotic pressure on the bounding surface of the spherical nano-shell. The
osmotic pressure can be negative (inward pressure), positive (outward pressure)
or zero, depending on the system parameters such as the charge density of the
droplet, the charge density of the shell, and the electrolyte screening, which
thus determine the stability of the nano-container. The counter-intuitive
effects of multivalent counterions comprise the increased stability of the
charged droplet with larger charge density, increased stability in the case of
encapsidating shell of charge density of the same sign as the charged droplet,
as well as the possibility to dispense altogether with the encapsidating shell,
its confining effect taken over by the multivalent counterions. These dramatic
effects are in stark contrast to the conventional mean-field picture, which in
particular implies that a more highly charged spherical droplet should be
electrostatically less stable because of its larger (repulsive) self-energy.


title:
Pareto optimal structures producing resonances of minimal decay under
  $L^1$-type constraints

abstract:
  Optimization of resonances associated with 1-D wave equations in
inhomogeneous media is studied under the constraint $\| B \|_1 <= m$ on the
nonnegative function $B \in L^1 (0,\ell)$ that represents the medium's
structure. From the Physics and Optimization points of view, it convenient to
generalize the problem replacing $B$ by a nonnegative measure $d M$ and
imposing on $d M$ the condition that its total mass is $<= m$. The problem is
to design for a given frequency $\alpha \in R$ a medium that generates a
resonance $ \omega $ on the line $\alpha + i R$ with a minimal possible decay
rate $| Im \omega |$. Such resonances are said to be of minimal decay and form
a Pareto frontier. We show that corresponding optimal measures consist of
finite number of point masses, and that this result yields non-existence of
optimizers for the problem over the set of absolutely continuous measures $B(x)
dx$. Then we derive restrictions on optimal point masses and their positions.
These restrictions are strong enough to calculate optimal $d M$ if the optimal
resonance $ \omega $, the first point mass $m_1$, and one more geometric
parameter are known. This reduces the original infinitely-dimensional problem
to optimization over four real parameters. For small frequencies, we explicitly
find the Pareto set and the corresponding optimal measures $d M$. The technique
of the paper is based on the two-parameter perturbation method and the notion
of local boundary point. The latter is introduced as a generalization of local
extrema to vector optimization problems.

categories: math.OC math-ph math.MP math.SP physics.optics


title:
Structure of 1-RSB asymptotic Gibbs measures in the diluted p-spin
  models

abstract:
  In this paper we study asymptotic Gibbs measures in the diluted p-spin models
in the so called 1-RSB case, when the overlap takes two values $q_*, q^*\in
[0,1].$ When the external field is not present and the overlap is not equal to
zero, we prove that such asymptotic Gibbs measures are described by the
M\'ezard-Parisi ansatz conjectured in [MP]. When the external field is present,
we prove that the overlap can not be equal to zero and all 1-RSB asymptotic
Gibbs measures are described by the M\'ezard-Parisi ansatz. Finally, we give a
characterization of the exceptional case when there is no external field and
the smallest overlap value is equal to zero, although it does not go as far as
the M\'ezard-Parisi ansatz. Our approach is based on the cavity computations
combined with the hierarchical exchangeability of pure states.


title:
Coherent manipulation of cold Rydberg atoms near the surface of an atom
  chip

abstract:
  Coherent superpositions of the 49s and 48s Rydberg states of cold Rb atoms
were studied near the surface of an atom chip. The superpositions were created
and manipulated using microwaves resonant with the two-photon 49s-48s
transition. Coherent behavior was observed using Rabi flopping, Ramsey
sequences, spin-echo and spin-locking. These results are discussed in the
context of Rydberg atoms as electric field noise sensors. We consider the
coherence of systems quadratically coupled to noise fields with 1/f^k power
spectral densities (k \approx 1).


title: Citation Counts and Evaluation of Researchers in the Internet Age

abstract:
  Bibliometric measures derived from citation counts are increasingly being
used as a research evaluation tool. Their strengths and weaknesses have been
widely analyzed in the literature and are often subject of vigorous debate. We
believe there are a few fundamental issues related to the impact of the web
that are not taken into account with the importance they deserve. We focus on
evaluation of researchers, but several of our arguments may be applied also to
evaluation of research institutions as well as of journals and conferences.


title: Interdependent network reciprocity in evolutionary games

abstract:
  Besides the structure of interactions within networks, also the interactions
between networks are of the outmost importance. We therefore study the outcome
of the public goods game on two interdependent networks that are connected by
means of a utility function, which determines how payoffs on both networks
jointly influence the success of players in each individual network. We show
that an unbiased coupling allows the spontaneous emergence of interdependent
network reciprocity, which is capable to maintain healthy levels of public
cooperation even in extremely adverse conditions. The mechanism, however,
requires simultaneous formation of correlated cooperator clusters on both
networks. If this does not emerge or if the coordination process is disturbed,
network reciprocity fails, resulting in the total collapse of cooperation.
Network interdependence can thus be exploited effectively to promote
cooperation past the limits imposed by isolated networks, but only if the
coordination between the interdependent networks is not disturbed.


title: Application of Quantum Stochastic Calculus to Feedback Control

abstract:
  The basic aspects of the Hudson-Parthasarathy quantum stochastic calculus and
of the Accardi-Fagnola-Quaegebeur representation free stochastic calculus are
presented. The basic features of the stochastic calculus for the square of
white noise recently developed by Accardi-Boukas are described. The feedback
control problem for stochastic processes driven by quantum noise is solved


title:
Modelling strong seismic ground motion: three-dimensional loading path
  versus wavefield polarization

abstract:
  Seismic waves due to strong earthquakes propagating in surficial soil layers
may both reduce soil stiffness and increase the energy dissipation into the
soil. To investigate seismic wave amplification in such cases, past studies
have been devoted to one-directional shear wave propagation in a soil column
(1D-propagation) considering one motion component only (1C-polarization). Three
independent purely 1C computations may be performed ('1D-1C' approach) and
directly superimposed in the case of weak motions (linear behaviour). This
research aims at studying local site effects by considering seismic wave
propagation in a 1-D soil profile accounting for the influence of the 3-D
loading path and non-linear hysteretic behaviour of the soil. In the proposed
'1D-3C' approach, the three components (3C-polarization) of the incident wave
are simultaneously propagated into a horizontal multilayered soil. A 3-D
non-linear constitutive relation for the soil is implemented in the framework
of the Finite Element Method in the time domain. The complex rheology of soils
is modelled by mean of a multisurface cyclic plasticity model of the
Masing-Prandtl-Ishlinskii-Iwan type. The great advantage of this choice is that
the only data needed to describe the model is the modulus reduction curve. A
parametric study is carried out to characterize the changes in the seismic
motion of the surficial layers due to both incident wavefield properties and
soil non-linearities. The numerical simulations show a seismic response
depending on several parameters such as polarization of seismic waves, material
elastic and dynamic properties, as well as on the impedance contrast between
layers and frequency content and oscillatory character of the input motion. The
3-D loading path due to the 3C-polarization leads to multi-axial stress
interaction that reduces soil strength and increases non-linear effects. The
non-linear behaviour of the soil may have beneficial or detrimental effects on
the seismic response at the free surface, depending on the energy dissipation
rate. Free surface time histories, stress-strain hysteresis loops and in-depth
profiles of octahedral stress and strain are estimated for each soil column.
The combination of three separate 1D-1C non-linear analyses is compared to the
proposed 1D-3C approach, evidencing the influence of the 3C-polarization and
the 3-D loading path on strong seismic motions.


title:
Identification of New Gamma-Ray Blazar Candidates With Multifrequency
  Archival Observations

abstract:
  Blazars are a highly-variable, radio-loud subclass of active galactic nuclei
(AGN). In order to better understand such objects we must be able to easily
identify candidate blazars from the growing population of unidentified sources.
Working towards this goal we attempt to identify new gamma-ray blazar
candidates from a sample of 102 previously unidentified sources. These sources
are selected from Astronomer's Telegrams and the literature on the basis of
non-periodic variability and multi-wavelength behavior. We then attempt to
associate these objects to an IR counterpart in the WISE all-sky survey. We are
able to identify sixteen candidate sources whose IR colors are consistent with
those of the blazar population. Of those sixteen, thirteen sources have IR
colors indicative of being gamma-ray emitting blazar candidates. These sources
all possess archival multi-wavelength observations that support their
blazar-like nature.


title:
Probing the Cosmic X-ray and MeV Gamma-ray Background Radiation through
  the Anisotropy

abstract:
  While the cosmic soft X-ray background is very likely to originate from
individual Seyfert galaxies, the origin of the cosmic hard X-ray and MeV
gamma-ray background is not fully understood. It is expected that Seyferts
including Compton thick population may explain the cosmic hard X-ray
background. At MeV energy range, Seyferts having non-thermal electrons in
coronae above accretion disks or MeV blazars may explain the background
radiation. We propose that future measurements of the angular power spectra of
anisotropy of the cosmic X-ray and MeV gamma-ray backgrounds will be key to
deciphering these backgrounds and the evolution of active galactic nuclei
(AGNs). As AGNs trace the cosmic large-scale structure, spatial clustering of
AGNs exists. We show that e-ROSITA will clearly detect the correlation signal
of unresolved Seyferts at 0.5-2 keV and 2-10 keV bands and will be able to
measure the bias parameter of AGNs at both bands. Once the future hard X-ray
all sky satellites achieve the sensitivity better than 10^{-12} erg/cm^2/s at
10-30 keV or 30-50 keV - although this is beyond the sensitivities of current
hard X-ray all sky monitors - angular power spectra will allow us to
independently investigate the fraction of Compton-thick AGNs in all Seyferts.
We also find that the expected angular power spectra of Seyferts and blazars in
the MeV range are different by about an order of magnitude, where the Poisson
term, so-called shot noise, is dominant. Current and future MeV instruments
will clearly disentangle the origin of the MeV gamma-ray background through the
angular power spectrum.


title:
Suppression of the Kondo Resistivity Minimum in Magnetic Topological
  Insulators

abstract:
  Magnetically-doped topological insulators are intensely studied in the search
for exotic phenomena such as the quantum anomalous Hall effect. The interplay
of electronic and impurity degrees of freedom leads to the Kondo effect, an
increase in the resistivity at temperatures $T < T_K$, the Kondo temperature.
We study this effect in chiral surface state transport at $T \ge T_K$ in the
metallic regime, starting from the quantum Liouville equation and including
Kondo scattering to all orders, as well as phonon and non-magnetic impurity
scattering. Unlike spin-orbit coupled metals and semiconductors, $T_K$ is
suppressed by spin-momentum locking which prevents the formation of a Kondo
screening cloud. We expect a resistivity $\rho_{xx} \propto T^4$ primarily due
to phonons.


title:
Effect of Gravitational Focusing on Annual Modulation in Dark-Matter
  Direct-Detection Experiments

abstract:
  The scattering rate at dark-matter direct-detection experiments should
modulate annually due to the Earth's orbit around the Sun. The rate is
typically thought to be extremized around June 1, when the relative velocity of
the Earth with respect to the dark-matter wind is maximal. We point out that
gravitational focusing can alter this modulation phase. Unbound dark-matter
particles are focused by the Sun's gravitational potential, affecting their
phase-space density in the lab frame. Gravitational focusing can result in a
significant overall shift in the annual-modulation phase, which is most
relevant for dark matter with low scattering speeds. The induced phase shift
for light O(10) GeV dark matter may also be significant, depending on the
threshold energy of the experiment.


title:
The Herschel Cold Debris Disks: Confusion with the Extragalactic
  Background at 160 mu

abstract:
  The Herschel "DUst around NEarby Stars (DUNES)" survey has found a number of
debris disk candidates that are apparently very cold, with temperatures near
22K. It has proven difficult to fit their spectral energy distributions with
conventional models for debris disks. Given this issue we carefully examine the
alternative explanation, that the detections arise from confusion with IR
cirrus and/or background galaxies that are not physically associated with the
foreground star. We find that such an explanation is consistent with all of
these detections.


title:
Heterotic G_2-manifold compactifications with fluxes and fermionic
  condensates

abstract:
  We consider flux compactifications of heterotic string theory in the presence
of fermionic condensates on M_{1,2} times X_7 with both factors carrying a
Killing spinor. In other words, M_{1,2} is either de Sitter, anti-de Sitter or
Minkowski, and X_7 possesses a nearly parallel G_2-structure or has
G_2-holonomy. We solve the complete set of field equations and the Bianchi
identity to order alpha'. The latter is satisfied via a non-standard embedding
by choosing the gauge field to be a G_2-instanton. It is shown that none of the
solutions to the field equations is supersymmetric.


title:
Resonant scattering in the Perseus Cluster: spectral model for
  constraining gas motions with Astro-H

abstract:
  X-ray spectra from cores of galaxy clusters can be strongly distorted by
resonant scattering of line photons, affecting metal abundance and gas velocity
measurements. We introduce simulated spectral models that take into account the
resonant scattering effect, radial variations of thermodynamic properties of
the hot gas, projection effects and small-scale isotropic gas motions. The key
feature of the models is that all these effects are treated self-consistently
for the whole spectrum, rather than for individual lines. The model spectra are
publicly available and can be used for direct comparison with observed
projected spectra. Comparison with the existing XMM-Newton and Chandra data of
the Perseus Cluster shows that even though there is no strong evidence for the
resonant scattering in Perseus, the low energy resolution of the X-ray CCDs is
not sufficient to robustly distinguish spectral distortions due to the resonant
scattering, different metal abundance profiles and different levels of gas
turbulence. Future Astro-H data will resolve most of the problems we are facing
with CCDs. With the help of our models, the resonant scattering analysis can be
done self-consistently using the whole spectral information, constraining the
level of gas turbulence already with a 100 ks observation with Astro-H.


title:
The Spectrally Resolved Lyman-alpha Emission of Three Lyman-alpha
  Selected Field Galaxies at z~2.4 from the HETDEX Pilot Survey

abstract:
  We present new results on the spectrally resolved Lyman-alpha (LyA) emission
of three LyA emitting field galaxies at z~2.4 with high LyA equivalent width
(>100 Angstroms) and LyA luminosity (~10^43 erg/s). At 120 km/s (FWHM) spectral
resolution, the prominent double-peaked LyA profile straddles the systemic
velocity, where the velocity zero-point is determined from spectroscopy of the
galaxies' rest-frame optical nebular emission lines. The average velocity
offset from systemic of the stronger redshifted emission component for our
sample is 176 km/s while the average total separation between the redshifted
and main blueshifted emission components is 380 km/s. These measurements are a
factor of ~2 smaller than for UV continuum-selected galaxies that show LyA in
emission with lower LyA equivalent width. We compare our LyA spectra to the
predicted line profiles of a spherical "expanding shell" LyA radiative transfer
grid that models large-scale galaxy outflows. Specifically blueward of the
systemic velocity where two galaxies show a weak, highly blueshifted (by ~1000
km/s) tertiary emission peak, the model line profiles are a relatively poor
representation of the observed spectra. Since the neutral gas column density
has a dominant influence over the shape of the LyA line profile, we caution
against equating the observed LyA velocity offset with a physical outflow
velocity, especially at lower spectral resolution where the unresolved LyA
velocity offset is a convoluted function of several degenerate parameters.
Referring to rest-frame ultraviolet and optical Hubble Space Telescope imaging,
we find that galaxy-galaxy interactions may play an important role in inducing
a starburst that results in copious LyA emission, as well as perturbing the gas
distribution and velocity field which have strong influence over the LyA
emission line profile.


title:
The Rich Globular Cluster System of Abell 1689 and the Radial Dependence
  of the Globular Cluster Formation Efficiency

abstract:
  We study the rich globular cluster (GC) system in the center of the massive
cluster of galaxies Abell 1689 (z=0.18), one of the most powerful gravitational
lenses known. With 28 HST/ACS orbits in the F814W bandpass, we reach magnitude
I_814=29 with >90% completeness and sample the brightest ~5% of the GC system.
Assuming the well-known Gaussian form of the GC luminosity function (GCLF), we
estimate a total population of N(GC_total) = 162,850 GCs within a projected
radius of 400kpc. As many as half may comprise an intracluster component. Even
with the sizable uncertainties, which mainly result from the uncertain GCLF
parameters, this is by far the largest GC system studied to date. The specific
frequency S_N is high, but not uncommon for central galaxies in massive
clusters, rising from S_N~5 near the center to ~12 at large radii. Passive
galaxy fading would increase S_N by ~20% at z=0. We construct the radial mass
profiles of the GCs, stars, intracluster gas, and lensing-derived total mass,
and we compare the mass fractions as a function of radius. The estimated mass
in GCs, M(GC_total)=3.9x10^10 Msun, is comparable to ~80% of the total stellar
mass of the Milky Way. The shape of the GC mass profile appears intermediate
between those of the stellar light and total cluster mass. Despite the extreme
nature of this system, the ratios of the GC mass to the baryonic and total
masses, and thus the GC formation efficiency, are typical of those in other
rich clusters when comparing at the same physical radii. The GC formation
efficiency is not constant, but varies with radius, in a manner that appears
similar for different clusters; we speculate on the reasons for this similarity
in profile.


title: On minimal Z' explanations of the B->K*mu+mu- anomaly

abstract:
  Recently LHCb has announced a discrepancy of 3.7 sigma in one of the
theoretically clean observables accessible through studies of angular
correlations in B->K*mu+mu-. We point out that in the most minimal Z' setup
that can address this anomaly there is a model-independent triple-correlation
between new physics (NP) in B->K*mu+mu-, B_s-Bbar_s mixing, and non-unitarity
of the quark-mixing matrix. This triple-correlation can be cast into a simple
analytic formula that relates the NP contribution DeltaC9 to the Wilson
coefficient of the semileptonic vector operator to a shift in the mass
difference DeltaM_{B_s} and a violation of |Vud|^2+ |Vus|^2+ |Vub|^2 = 1. In
contrast to the individual observables the found relation depends only
logarithmically on the Z' mass. We show that that our findings allow for useful
future tests of the pattern of NP suggested by the B->K*mu+mu- anomaly.


title: Maxwell Theory on a Compact Manifold as a Topologically Ordered System

abstract:
  We study novel type of contributions to the entropy of the Maxwell system
defined on a compact manifold such as torus. These new terms are not related to
the physical propagating photons. Rather, these novel contributions emerge as a
result of tunnelling events when transitions occur between topologically
different but physical identical vacuum winding states. We compute two new
(topologically protected) types of contributions to the entropy in this system
resulting from this dynamics. First contribution has a negative sign, expressed
in terms of the magnetic susceptibility, and it is similar in spirit to
topological entanglement entropy discussed in condensed matter systems. The
second contribution with a positive sign results from the emergent degeneracy
which occurs when the system is placed into a background of external magnetic
field. This degeneracy resembles a similar effect which occurs at \theta=\pi in
topological insulators. Based on these computations we claim that the Maxwell
system defined on 4 torus behaves in many respects as a topologically ordered
system.


title:
Ferromagnetism of the Repulsive Atomic Fermi Gas: three-body
  recombination and domain formation

abstract:
  The simplest model for itinerant ferromagnetism, the Stoner model, has so far
eluded experimental observation in repulsive ultracold fermions due to rapid
three-body recombination at large scattering lengths. Here we show that a
ferromagnetic phase can be stabilised by imposing a moderate optical lattice.
The reduced kinetic energy drop upon formation of a polarized phase in an
optical lattice extends the ferromagnetic phase to smaller scattering lengths
where three-body recombination is small enough to permit experimental detection
of the phase. We also show, using time dependent density functional theory,
that in such a setup ferromagnetic domains emerge rapidly from a paramagnetic
initial state.


title: Magnetic Breakdown in Twisted Bilayer Graphene

abstract:
  We consider magnetic breakdown in twisted bilayer graphene where electrons
may hop between semiclassical $k$-space trajectories in different layers. These
trajectories within a doubled Brillouin zone constitute a network in which an
$S$-matrix at each saddle point is used to model tunneling between different
layers. Matching of the semiclassical wavefunctions throughout the network
determines the energy spectrum. Semiclassical orbits with energies well below
that of the saddle points are Landau levels of the Dirac points in each layer.
These continuously evolve into {\it both} electron-like and hole-like levels
above the saddle point energy. Possible experimental signatures are discussed.


title:
Evolution of IEEE 802.11 compatible standards and impact on Energy
  Consumption

abstract:
  Over the last decade, the IEEE 802.11 has emerged as the most popular
protocol in the wireless domain. Since the release of the first standard
version, several amendments have been introduced in an effort to improve its
throughput performance, with the most recent one being the IEEE 802.11n
extension. In this work, we present detailed experimentally obtained
measurements that evaluate the energy efficiency of the base standard in
comparison with the latest 802.11n version. Moreover, we investigate the impact
of various MAC layer enhancements, both vendor specific and standard compliant
ones, on the energy consumption of wireless transceivers and total nodes as
well. Results obtained under a wide range of settings, indicate that the latest
standard enables reduction of energy expenditure, by more than 75%, when
combined with innovative frame aggregation mechanisms.


title: Dynamics of warped accretion discs

abstract:
  Accretion discs are present around both stellar-mass black holes in X-ray
binaries and supermassive black holes in active galactic nuclei. A wide variety
of circumstantial evidence implies that many of these discs are warped. The
standard Bardeen--Petterson model attributes the shape of the warp to the
competition between Lense--Thirring torque from the central black hole and
viscous angular-momentum transport within the disc. We show that this
description is incomplete, and that torques from the companion star (for X-ray
binaries) or the self-gravity of the disc (for active galactic nuclei) can play
a major role in determining the properties of the warped disc. Including these
effects leads to a rich set of new phenomena. For example, (i) when a companion
star is present and the warp arises from a misalignment between the companion's
orbital axis and the black hole's spin axis, there is no steady-state solution
of the Pringle--Ogilvie equations for a thin warped disc when the viscosity
falls below a critical value; (ii) in AGN accretion discs, the warp can excite
short-wavelength bending waves that propagate inward with growing amplitude
until they are damped by the disc viscosity. We show that both phenomena can
occur for plausible values of the black hole and disc parameters, and briefly
discuss their observational implications.


title: A low-loss photonic silica nanofiber for higher-order modes

abstract:
  Optical nanofibers confine light to subwavelength scales, and are of interest
for the design, integration, and interconnection of nanophotonic devices. Here
we demonstrate high transmission (> 97%) of the first family of excited modes
through a 350 nm radius fiber, by appropriate choice of the fiber and precise
control of the taper geometry. We can design the nanofibers so that these modes
propagate with most of their energy outside the waist region. We also present
an optical setup for selectively launching these modes with less than 1%
fundamental mode contamination. Our experimental results are in good agreement
with simulations of the propagation. Multimode optical nanofibers expand the
photonic toolbox, and may aid in the realization of a fully integrated
nanoscale device for communication science, laser science or other sensing
applications.


title: Influence of quantum energy equation on electronic plasma oscillations

abstract:
  Five-moment approximation in hydrodynamics includes not only continuity
equation and momentum balance equation, but also energy equation. Set of
hydrodynamic equations is presented for system of non-relativistic quantum
particles with Coulomb interaction. This set of equations is linearized, and
dispersion relation for Langmuir waves in quasi-neutral system of electrons and
immobile ions is obtained.