title:
Optical initialization of hole spins in p-doped quantum dots:
  orientation efficiency and loss of coherence

abstract:
  We study theoretically the recently proposed hole spin initialization scheme
for $p$-doped quantum well or dot systems via coupling to trion states with
sub-picosecond circularly polarized laser pulses. We analyze the efficiency of
spin initialization an predict the intrinsic spin coherence loss due to the
pulse excitation itself as well as the phonon-induced spin dephasing, both
taking place on the timescale of the driving laser pulse. We show that the
ratio of the degree of dephasing to the achieved orientation effect does not
depend on the pulse area but is sensitive to the temperature and detuning. The
optimal excitation parameters are identified.


title:
Gravitational and electric energies in the collapse of a spherical
  thin-shell capacitor

abstract:
  We adopt a simplified model describing the collapse of a spherical thin-shell
capacitor to give an analytical description how gravitational energy is
converted to both kinetic and electric energies in the gravitational collapse.
It is shown that (i) averaged kinetic and electric energies are the same order,
about an half of gravitational energy of spherical thin-shell capacitor in the
collapse; (ii) caused by radiating and rebuilding electric energy, the
gravitational collapse undergoes a sequence of "on and off" hopping steps in
the microscopic Compton scale. Although the collapse process is still
continuous in terms of macroscopic scales, it is slowed down as the kinetic
energy is reduced and collapsing time is about an order of magnitude larger
than that of the collapse process eliminating electric processes.


title:
On the nature of veiling of classical T Tauri stars spectra in the
  near-IR spectral band

abstract:
  It is shown that the existence of a hot accretion spot on the surface of
classical T Tauri stars allows to explain observed veiling of their
photospheric spectrum not only in the visible but also in the near infrared
spectral band.


title: Quantization of Perturbations in Inflation

abstract:
  The derivation of the angular spectrum of temperature perturbations of the
cosmic microwave background relies on the quantization of field and metric
perturbations in the inflationary phase. The quantization procedure thus
deserves a close examination. As the background spacetime on which the degrees
of freedom that are quantized live is curved, the methods of quantum field
theory in curved spacetimes are applicable. Furthermore the dynamic system that
is quantized contains a constraint, which adds an interesting problem to the
quantization of the system. This article investigates the treatment of the
constraints and the Weyl quantization of the system. A preferred quantization
procedure is identified, which renders the field and metric perturbations
non-local.


title:
A simple Local Interstellar Spectrum model to fit the proton fluxes
  measured by the AMS and PAMELA detectors

abstract:
  In this paper we discuss some simple analytical models to fit the cosmic-ray
(CR) proton data collected by the AMS detector in June 1998 and by the PAMELA
detector in several campaigns covering the period 2006-2009. The CR proton
spectrum at Earth is derived starting from the model of the local interstellar
spectrum (LIS) and folding it with the solar modulation potential in the force
field approximation. The data are well described by a LIS modeled with a simple
power law particle momentum density.


title:
Probing hot electron transport across an epitaxial Schottky interface of
  SrRuO3/Nb:SrTiO3

abstract:
  SrRuO3 (SRO), a conducting transition metal oxide, is commonly used for
engineering domains in BiFeO3. New oxide devices can be envisioned by
integrating SRO with an oxide semiconductor as Nb doped SrTiO3 (Nb:STO). Using
a three-terminal device configuration, we study vertical transport in a
SRO/Nb:STO device at the nanoscale and find local differences in transport,
that originate due to the high selectivity of SRO growth on the underlying
surface terminations in Nb:STO. This causes a change in the interface energy
band characteristics and is explained by the differences in the spatial
distribution of the interface-dipoles at the local Schottky interface.


title:
The coexistence and evolution of attractors in the web map with weak
  dissipation

abstract:
  The dynamics of the web map with weak linear dissipation is studied. The
evolution of the coexisting attractors and the structure of their basins while
changing the dissipation and nonlinearity are revealed. It is shown that the
structure of the basins remains the same when the dissipation and nonlinearity
changes simultaneously.


title:
Remarks on the Aharonov-Casher dynamics in a CPT-odd Lorentz-violating
  background

abstract:
  The Aharonov-Casher problem in the presence of a Lorentz-violating background
nonminimally coupled to a spinor and a gauge field is examined. Using an
approach based on the self-adjoint extension method, an expression for the
bound state energies is obtained in terms of the physics of the problem by
determining the self-adjoint extension parameter.


title: Semiclassical Cauchy Estimates and Applications

abstract:
  In this note, we study solutions to semiclassical Schrodinger equations on a
real analytic manifold with a real analytic potential and prove the
semiclassical version of Cauchy estimates on derivatives. As an application, we
use Donnelly and Fefferman's method to prove the upper and lower bounds for
(n-1)-dimensional Hausdorff measure of the nodal sets of the solutions to
semiclassical Schrodinger equations.


title: Gravity-related wave function collapse: Is superfluid He exceptional?

abstract:
  The gravity-related model of spontaneous wave function collapse, a longtime
hypothesis, damps the massive Schr\"odinger Cat states in quantum theory. We
extend the hypothesis and assume that spontaneous wave function collapses are
responsible for the emergence of Newton interaction. Superfluid helium would
then show significant and testable gravitational anomalies.


title: Gravity-related wave function collapse: mass density resolution

abstract:
  Selected issues of the concept of spontaneous collapse are discussed, with
the emphasis on the gravity-related model. We point out that without
spontaneous collapses the Schr\"odinger cat states would macroscopically
violate the standard conservation laws even in the presence of environmental
noise. We prove that the collapse time of condensed matter c.o.m.
superpositions is not sensitive to the natural uncertainty of the nuclear
locations whereas we formulate the conjecture that superfluid He may show an
anomalous low rate of spontaneous collapse compared to common condensed matter.


title: Testing Uniformity of Stationary Distribution

abstract:
  A random walk on a directed graph gives a Markov chain on the vertices of the
graph. An important question that arises often in the context of Markov chain
is whether the uniform distribution on the vertices of the graph is a
stationary distribution of the Markov chain. Stationary distribution of a
Markov chain is a global property of the graph. In this paper, we prove that
for a regular directed graph whether the uniform distribution on the vertices
of the graph is a stationary distribution, depends on a local property of the
graph, namely if (u,v) is an directed edge then outdegree(u) is equal to
indegree(v).
  This result also has an application to the problem of testing whether a given
distribution is uniform or "far" from being uniform. This is a well studied
problem in property testing and statistics. If the distribution is the
stationary distribution of the lazy random walk on a directed graph and the
graph is given as an input, then how many bits of the input graph do one need
to query in order to decide whether the distribution is uniform or "far" from
it? This is a problem of graph property testing and we consider this problem in
the orientation model (introduced by Halevy et al.). We reduce this problem to
test (in the orientation model) whether a directed graph is Eulerian. And using
result of Fischer et al. on query complexity of testing (in the orientation
model) whether a graph is Eulerian, we obtain bounds on the query complexity
for testing whether the stationary distribution is uniform.


title:
A survey of young, nearby, and dusty stars to understand the formation
  of wide-orbit giant planets

abstract:
  Direct imaging has confirmed the existence of substellar companions on wide
orbits. To understand the formation and evolution mechanisms of these
companions, the full population properties must be characterized. We aim at
detecting giant planet and/or brown dwarf companions around young, nearby, and
dusty stars. Our goal is also to provide statistics on the population of giant
planets at wide-orbits and discuss planet formation models. We report a deep
survey of 59 stars, members of young stellar associations. The observations
were conducted with VLT/NaCo at L'-band (3.8 micron). We used angular
differential imaging to reach optimal detection performance. A statistical
analysis of about 60 % of the young and southern A-F stars closer than 65 pc
allows us to derive the fraction of giant planets on wide orbits. We use
gravitational instability models and planet population synthesis models
following the core-accretion scenario to discuss the occurrence of these
companions. We resolve and characterize new visual binaries and do not detect
any new substellar companion. The survey's median detection performance reaches
contrasts of 10 mag at 0.5as and 11.5 mag at 1as. We find the occurrence of
planets to be between 10.8-24.8 % at 68 % confidence level assuming a uniform
distribution of planets in the interval 1-13 Mj and 1-1000 AU. Considering the
predictions of formation models, we set important constraints on the occurrence
of massive planets and brown dwarf companions that would have formed by GI. We
show that this mechanism favors the formation of rather massive clump (Mclump >
30 Mj) at wide (a > 40 AU) orbits which might evolve dynamically and/or
fragment. For the population of close-in giant planets that would have formed
by CA, our survey marginally explore physical separations (<20 AU) and cannot
constrain this population.


title:
Hot electron attenuation of direct and scattered carriers across an
  epitaxial Schottky interface

abstract:
  Hot electron transport of direct and scattered carriers across an epitaxial
NiSi_2/n-Si(111) interface, for different NiSi_2 thickness, is studied using
Ballistic Electron Emission Microscopy (BEEM). We find the BEEM transmission
for the scattered hot electrons in NiSi_2 to be significantly lower than that
for the direct hot electrons, for all thicknesses. Interestingly, the
attenuation length of the scattered hot electrons is found to be twice larger
than that of the direct hot electrons. The lower BEEM transmission for the
scattered hot electrons is due to inelastic scattering of the injected hot
holes while the larger attenuation length of the scattered hot electrons is a
consequence of the differences in the energy distribution of the injected and
scattered hot electrons and the increasing attenuation length, at lower
energies, of the direct hot electrons in NiSi_2.


title:
Origin of the phase transition in IrTe2: structural modulation and local
  bonding instability

abstract:
  We used X-ray/neutron diffraction to determine the low temperature (LT)
structure of IrTe2. A structural modulation was observed with a wavevector of k
=(1/5, 0, 1/5) below Ts?285 K, accompanied by a structural transition from a
trigonal to a triclinic lattice. We also performed the first principles
calculations for high temperature (HT) and LT structures, which elucidate the
nature of the phase transition and the LT structure. A local bonding
instability associated with the Te 5p states is likely the origin of the
structural phase transition in IrTe2.


title:
Strictly ascending HNN extensions of finite rank free groups that are
  linear over Z

abstract:
  We find strictly ascending HNN extensions of finite rank free groups
possessing a presentation 2-complex which is a non positively curved square
complex. On showing these groups are word hyperbolic, we have by results of
Wise and Agol that they are linear over the integers. An example is the
endomorphism of the free group on a,b with inverses A,B that sends a to aBaab
and b to bAbba.


title: Non-Linear Distributed Average Consensus using Bounded Transmissions

abstract:
  A distributed average consensus algorithm in which every sensor transmits
with bounded peak power is proposed. In the presence of communication noise, it
is shown that the nodes reach consensus asymptotically to a finite random
variable whose expectation is the desired sample average of the initial
observations with a variance that depends on the step size of the algorithm and
the variance of the communication noise. The asymptotic performance is
characterized by deriving the asymptotic covariance matrix using results from
stochastic approximation theory. It is shown that using bounded transmissions
results in slower convergence compared to the linear consensus algorithm based
on the Laplacian heuristic. Simulations corroborate our analytical findings.


title: Polyhedral structures on tropical varieties

abstract:
  Tropical varieties are polyhedral shadows of classical varieties. The purpose
of these expository notes is to explain the origin of this polyhedral complex
structure from the perspective of Gr\"obner bases. To appear in the proceedings
of the 2011 Bellairs Workshop in Number Theory.


title: Vitushkin-type theorems

abstract:
  It is shown that for a subset $A\subset\R^n$ that has the global Gabrielov
property, a Vitushkin-type estimate holds. Concrete examples are given for
sub-level sets of certain classes of functions.


title:
A Weight-coded Evolutionary Algorithm for the Multidimensional Knapsack
  Problem

abstract:
  A revised weight-coded evolutionary algorithm (RWCEA) is proposed for solving
multidimensional knapsack problems. This RWCEA uses a new decoding method and
incorporates a heuristic method in initialization. Computational results show
that the RWCEA performs better than a weight-coded evolutionary algorithm
proposed by Raidl (1999) and to some existing benchmarks, it can yield better
results than the ones reported in the OR-library.


title:
Precovery of near-Earth asteroids by a citizen-science project of the
  Spanish Virtual Observatory

abstract:
  This article describes a citizen-science project conducted by the Spanish
Virtual Observatory (SVO) to improve the orbits of near-Earth asteroids (NEAs)
using data from astronomical archives. The list of NEAs maintained at the Minor
Planet Center (MPC) is checked daily to identify new objects or changes in the
orbital parameters of already catalogued objects. Using NEODyS we compute the
position and magnitude of these objects at the observing epochs of the 938 046
images comprising the Eigth Data Release of the Sloan Digitised Sky Survey
(SDSS). If the object lies within the image boundaries and the magnitude is
brighter than the limiting magnitude, then the associated image is visually
inspected by the project's collaborators (the citizens) to confirm or discard
the presence of the NEA. If confirmed, accurate coordinates and, sometimes,
magnitudes are submitted to the MPC. Using this methodology, 3,226 registered
users have made during the first fifteen months of the project more than
167,000 measurements which have improved the orbital elements of 551 NEAs (6%
of the total number of this type of asteroids). Even more remarkable is the
fact that these results have been obtained at zero cost to telescope time as
NEAs were serendipitously observed while the survey was being carried out. This
demonstrates the enormous scientific potential hidden in astronomical archives.
  The great reception of the project as well as the results obtained makes it a
valuable and reliable tool for improving the orbital parameters of near-Earth
asteroids.


title: Spatial CSIT Allocation Policies for Network MIMO Channels

abstract:
  In this work, we study the problem of the optimal dissemination of channel
state information (CSI) among K spatially distributed transmitters (TXs)
jointly cooperating to serve K receivers (RXs). One of the particularities of
this work lies in the fact that the CSI is distributed in the sense that each
TX obtains its own estimate of the global multi-user MIMO channel with no
further exchange of information being allowed between the TXs. Although this is
well suited to model the cooperation between non-colocated TXs, e.g., in
cellular Coordinated Multipoint (CoMP) schemes, this type of setting has
received little attention so far in the information theoretic society. We study
in this work what are the CSI requirements at every TX, as a function of the
network geometry, to ensure that the maximal number of degrees-of-freedom (DoF)
is achieved, i.e., the same DoF as obtained under perfect CSI at all TXs. We
advocate the use of the generalized DoF to take into account the geometry of
the network in the analysis. Consistent with the intuition, the derived DoF
maximizing CSI allocation policy suggests that TX cooperation should be limited
to a specific finite neighborhood around each TX. This is in sharp contrast
with the conventional (uniform) CSI dissemination policy which induces CSI
requirements that grow unbounded with the network size. The proposed CSI
allocation policy suggests an alternative to clustering which overcomes
fundamental limitations such as (i) edge interference and (ii) unbounded
increase of the CSIT requirements with the cluster size. Finally, we show how
finite neighborhood CSIT exchange translates into finite neighborhood message
exchange so that finally global interference management is possible with only
local cooperation


title: A preliminary reconstruction of the orbit of the Chelyabinsk Meteoroid

abstract:
  In February 15 2013 a medium-sized meteoroid impacted the atmosphere in the
region of Chelyabinsk, Russia. After its entrance to the atmosphere and after
travel by several hun- dred of kilometers the body exploded in a powerful event
responsible for physical damages and injured people spread over a region
enclosing several large cities. We present in this letter the results of a
preliminary reconstruction of the orbit of the Chelyabinsk meteoroid. Using
evidence gathered by one camera at the Revolution Square in the city of
Chelyabinsk and other videos recorded by witnesses in the close city of
Korkino, we calculate the trajectory of the body in the atmosphere and use it
to reconstruct the orbit in space of the meteoroid previous to the violent
encounter with our planet. In order to account for the uncertainties implicit
in the determination of the trajectory of the body in the atmosphere, we use
Monte Carlo methods to calculate the most probable orbital parameters. We use
this result to classify the meteoroid among the near Earth asteroid families
finding that the parent body belonged to the Apollo asteroids. Although
semimajor axis and inclination of the preliminary orbit computed by us are
uncertain, the rest of orbital elements are well constrained in this
preliminary reconstruction.


title: Sensitive Absorption Imaging of Single Atoms in Front of a Mirror

abstract:
  In this paper we show that the sensitivity of absorption imaging of ultracold
atoms can be significantly improved by imaging in a standing-wave
configuration. We present simulations of single-atom absorption imaging both
for a travelling-wave and a standing-wave imaging setup, based on a scattering
approach to calculate the optical density of a single atom. We find that the
optical density of a single atom is determined only by the numerical aperture
of the imaging system. We determine optimum imaging parameters, taking all
relevant sources of noise into account. For reflective imaging we find an
improvement of 1.7 in the maximum signal-to-noise ratio can be achieved. This
is particularly useful for imaging in the vicinity of an atom chip, where a
reflective surface is naturally present.


title:
Electronic transport on carbon nanotube networks: a multiscale
  computational approach

abstract:
  Carbon nanotube networks are one of the candidate materials to function as
malleable, transparent, conducting films, with the technologically promising
application of being used as flexible electronic displays. Nanotubes disorderly
distributed in a film offers many possible paths for charge carriers to travel
across the entire system, but the theoretical description of how this charge
transport occurs is rather challenging for involving a combination of intrinsic
nanotube properties with network morphology aspects. Here we attempt to
describe the transport properties of such films in two different length scales.
Firstly, from a purely macroscopic point of view we carry out a geometrical
analysis that shows how the network connectivity depends on the nanotube
concentration and on their respective aspect ratio. Once this is done, we are
able to calculate the resistivity of a heavily disordered networked film.
Comparison with experiment offers us a way to infer about the junction
resistance between neighbouring nanotubes. Furthermore, in order to guide the
frantic search for high-conductivity films of nanotube networks, we turn to the
microscopic scale where we have developed a computationally efficient way for
calculating the ballistic transport across these networks. While the ballistic
transport is probably not capable of describing the observed transport
properties of these films, it is undoubtedly useful in establishing an upper
value for their conductivity. This can serve as a guideline in how much room
there is for improving the conductivity of such networks.


title:
Statistical Characterization of Self-Assembled Colloidal Crystals by
  Single-Step Vertical Deposition

abstract:
  We have statistically characterized the self-assembly of multi-layer
polystyrene colloidal crystals, using the technique of vertical deposition,
with parameters chosen to produce thick layers of self-assembled crystals in
one deposition step. In addition, using a lithographically directed
self-assembly method, we have shown that the size of multi-layer, continuous
crack-free domains in lithographically defined areas can be many times larger
than in the surrounding areas. In a single deposition step, we have produced
continuous colloidal crystal films of 260 nm diameter polystyrene spheres
approximately 30 -- 40 layers thick, with a controllable lateral size of 80 --
100 $\upmu$m without lithography, and as high as 250 $\upmu$m with the
lithographic template.


title:
Top-antitop pair hadroproduction in association with a heavy boson at
  the NLO QCD accuracy + Parton Shower

abstract:
  The PowHel framework allows to make predictions of total and differential
cross-sections of multiparticle hadroproduction processes at both NLO QCD
accuracy and NLO QCD matched to Parton Shower, on the basis of the interface
between the POWHEG-BOX and HELAC-NLO codes. It has already been applied to
study several processes involving a top-antitop pair in association with a
third particle or hadronic jet. Our most recent predictions concern
top-antitop-V hadroproduction (with V = W or Z), at both parton and hadron
level, by considering different decay channels (hadronic and leptonic) of the
heavy particles. In particular, we show the results of our phenomenological
analyses under the same system of cuts also recently adopted by the CMS
collaboration at LHC.


title: Reversible Logic Synthesis by Quantum Rotation Gates

abstract:
  A rotation-based synthesis framework for reversible logic is proposed. We
develop a canonical representation based on binary decision diagrams and
introduce operators to manipulate the developed representation model.
Furthermore, a recursive functional bi-decomposition approach is proposed to
automatically synthesize a given function. While Boolean reversible logic is
particularly addressed, our framework constructs intermediate quantum states
that may be in superposition, hence we combine techniques from reversible
Boolean logic and quantum computation. The proposed approach results in
quadratic gate count for multiple-control Toffoli gates without ancillae,
linear depth for quantum carry-ripple adder, and quasilinear size for quantum
multiplexer.


title: Stochastic Ordering of Fading Channels Through the Shannon Transform

abstract:
  A new stochastic order between two fading distributions is introduced. A
fading channel dominates another in the ergodic capacity ordering sense, if the
Shannon transform of the first is greater than that of the second at all values
of average signal to noise ratio. It is shown that some parametric fading
models such as the Nakagami-m, Rician, and Hoyt are distributions that are
monotonic in their line of sight parameters with respect to the ergodic
capacity order. Some operations under which the ergodic capacity order is
preserved are also discussed. Through these properties of the ergodic capacity
order, it is possible to compare under two different fading scenarios, the
ergodic capacity of a composite system involving multiple fading links with
coding/decoding capabilities only at the transmitter/receiver. Such comparisons
can be made even in cases when a closed form expression for the ergodic
capacity of the composite system is not analytically tractable. Applications to
multiple access channels, and extensions to multiple-input multiple-output
(MIMO) systems are also discussed.


title: Facilitating Machine to Machine (M2M) Communication using GSM Network

abstract:
  In this paper a method to facilitate M2M communication using existing GSM
networks is proposed - as M2M devices primarily use SMS as their data bearer,
the focus is on increasing the number of devices that can use the associated
GSM signaling channels at a time. This is achieved by defining a new class of
low mobility, static M2M devices which use a modified physical layer control
frame structure. The proposal is expected to aid a quick, reliable and
cost-effective deployment of M2M devices in the existing GSM networks.


title:
Stochastic coupling in two modes systems: the weak-strong coupling
  transition

abstract:
  We investigate the weak-strong coupling transition of two linearly coupled
systems under the influence of a phase fluctuating coupling. In the weak
coupling regime the exponential decay of quantum properties is well known. A
different scenario occurs in the strong coupling regime, the inhibition of the
dynamics which tends to "freeze" as the ration between coupling strength and
average phase fluctuation time increase. Exciton-polariton oscillations and the
self-trapping phenomenon in Bose-Einstein Condensate qualitatively illustrate
the weak and strong regimes respectively.


title:
Homogenization for nonlinear PDEs in general domains with oscillatory
  Neumann boundary data

abstract:
  In this article we investigate averaging properties of fully nonlinear PDEs
in bounded domains with oscillatory Neumann boundary data. The oscillation is
periodic and is present both in the operator and in the Neumann data. Our main
result states that, when the domain does not have flat boundary parts and when
the homogenized operator is rotation invariant, the solutions uniformly
converge to the homogenized solution solving a Neumann boundary problem.
Furthermore we show that the homogenized Neumann data is continuous with
respect to the normal direction of the boundary.


title: Pseudo-differential calculus on homogeneous trees

abstract:
  In the objective of studying concentration and oscillation properties of
eigenfunctions of the discrete Laplacian on regular graphs, we construct a
pseudo-differential calculus on homogeneous trees, their universal covers. We
define symbol classes and associated operators. We prove that these operators
are bounded on L^2 and give adjoint and product formulas. Finally we compute
the symbol of the commutator of a pseudo-differential operator with the
Laplacian.


title:
Martin boundary of random walks with unbounded jumps in hyperbolic
  groups

abstract:
  Given a probability measure on a finitely generated group, its Martin
boundary is a natural way to compactify the group using the Green function of
the corresponding random walk. For finitely supported measures in hyperbolic
groups, it is known since the work of Ancona and Gou{\"e}zel-Lalley that the
Martin boundary coincides with the geometric boundary. The goal of this paper
is to weaken the finite support assumption. We first show that, in any
non-amenable group, there exist probability measures with exponential tails
giving rise to pathological Martin boundaries. Then, for probability measures
with superexponential tails in hyperbolic groups, we show that the Martin
boundary coincides with the geometric boundary by extending Ancona's
inequalities. We also deduce asymptotics of transition probabilities for
symmetric measures with superexponential tails.


title:
Vacuum magnetic linear birefringence using pulsed fields: the BMV
  experiment

abstract:
  We present the current status of the BMV experiment. Our apparatus is based
on an up-to-date resonant optical cavity coupled to a transverse magnetic
field. We detail our data acquisition and analysis procedure which takes into
account the symmetry properties of the raw data with respect to the orientation
of the magnetic field and the sign of the cavity birefringence. The measurement
result of the vacuum magnetic linear birefringence k_\mathrm{CM}$ presented in
this paper was obtained with about 200 magnetic pulses and a maximum field of
6.5\,T, giving a noise floor of about $8 \times 10^{-21}$\,T$^{-2}$ at
$3\sigma$ confidence level.


title:
The cutoff-dependence of the Casimir force within an inhomogeneous
  medium

abstract:
  We consider the ground state energy of the electromagnetic field in a piston
geometry. In the idealised case, where the piston and the walls of the chamber
are taken as perfect mirrors, the Casimir pressure on the piston is finite and
independent of the small scale physics of the media that compose the mirrors;
the Casimir-energy of the system can be regularised and is cutoff-independent.
Yet we find that, when the body of the piston is filled with an inhomogeneous
dielectric medium, the Casimir energy is cutoff-dependent, and the value of the
pressure is thus inextricably dependent on the detailed behaviour of the mirror
and the medium at large wave-vectors. This result is inconsistent with recent
proposals for regularising Casimir forces in inhomogeneous media.


title: Combinatorics of $\phi$-deformed stuffle Hopf algebras

abstract:
  In order to extend the Sch\"utzenberger's factorization to general
perturbations, the combinatorial aspects of the Hopf algebra of the
$\phi$-deformed stuffle product is developed systematically in a parallel way
with those of the shuffle product.


title: History of malware

abstract:
  In past three decades almost everything has changed in the field of malware
and malware analysis. From malware created as proof of some security concept
and malware created for financial gain to malware created to sabotage
infrastructure. In this work we will focus on history and evolution of malware
and describe most important malwares.


title: The omega-rule interpretation of transfinite provability logic

abstract:
  In this paper we consider transfinite provability logics where for each
ordinal in some recursive well-order we have a corresponding modal provability
operator. The modality [xi] will be interpreted as "provable in ACA_0 together
with at most xi nested applications of the omega rule". We show how to
formalize this in in second order number theory. Next we prove both soundness
and completeness under this interpretation. We conclude by showing how one can
lower the base theory ACA_0 to theories below RCA_0.


title: On Chromatic Number of Kneser Hypergraphs

abstract:
  In this paper, in view of $Z_p$-Tucker lemma, we introduce a lower bound for
chromatic number of Kneser hypergraphs which improves
Dol'nikov-K{\v{r}}{\'{\i}}{\v{z}} bound. Next, we introduce multiple Kneser
hypergraphs and we specify the chromatic number of some multiple Kneser
hypergraphs. For a vector of positive integers $\vec{s}=(s_1,s_2,\ldots,s_m)$
and a partition $\pi=(P_1,P_2,\ldots,P_m)$ of $\{1,2,\ldots,n\}$, the multiple
Kneser hypergraph ${\rm KG}^r(\pi; \vec{s};k)$ is a hypergraph with the vertex
set $$V=\left\{A:\ A\subseteq P_1\cup P_2\cup\cdots \cup P_m,\ |A|=k, \forall
1\leq i\leq m;\ |A\cap P_i|\leq s_i\right\}$$ whose edge set is consist of any
$r$ pairwise disjoint vertices. We determine the chromatic number of multiple
Kneser hypergraphs provided that $r=2$ or for any $1\leq i\leq m$, we have
$|P_i|\leq 2s_i$.
  A subset $S \subseteq [n]$ is almost $s$-stable if for any two distinct
elements $i,j\in S$, we have $|i-j|\geq s$. The almost $s$-stable Kneser
hypergraph ${\rm KG}^r(n,k)_{s-stab}^{\sim}$ has all $s$-stable subsets of
$[n]$ as the vertex set and every $r$-tuple of pairwise disjoint vertices forms
an edge. Meunier [The chromatic number of almost stable Kneser hypergraphs. J.
Combin. Theory Ser. A, 118(6):1820--1828, 2011] showed for any positive integer
$r$, $\chi({\rm KG}^r(n,k)_{2-stab}^{\sim})=\left\lceil {n-r(k-1) \over
r-1}\right\rceil$. We extend this result to a large family of Schrijver
hypergraphs. Finally, we present a colorful-type result which confirms the
existence of a completely multicolored complete bipartite graph in any coloring
of a graph.


title:
Weingarten surfaces with moving frames -- a tribute to S.S. Chern and
  C.L. Terng -- and a duality result

abstract:
  The techniques used in this paper are based on the exterior calculus of
Maurer-Cartan forms, and Weingarten surfaces are used to illustrate the methods
that apply to quadratic exterior equations with constant coefficients.
Isothermic {\it surfaces of constant astigmatism} (non-linear Weingarten
surfaces whose difference of principal curvatures is a constant) are shown to
represent dual surfaces of isothermic surfaces which satisfy the relation $H +
\alpha K = 0$.


title: Two classes of ODE models with switch-like behavior

abstract:
  In cases where the same real-world system can be modeled both by an ODE
system $\bD$ and a Boolean system $\bB$ it is of interest to identify
conditions under which the two systems will be consistent, that is, will make
qualitatively equivalent predictions. In this note we introduce two broad
classes of relatively simple models that provide a convenient framework for
studying such questions. In contrast to the widely known class of Glass
networks, the right-hand sides of our ODEs are Lipschitz-continuous. We prove
that under suitable assumptions about $\bB$ consistency between $\bD$ and $\bB$
will be implied by sufficient separation of time scales in one class of our
models while it may fail in the other class. These results appear to point to
more general structure properties that favor consistency between ODE and
Boolean models.


title:
Boundary element method and simulated annealing algorithm applied to
  electrical impedance tomography image reconstruction

abstract:
  Physics has played a fundamental role in medicine sciences, specially in
imaging diagnostic. Currently, image reconstruction techniques are already
taught in Physics courses and there is a growing interest in new potential
applications. The aim of this paper is to introduce to students the electrical
impedance tomography, a promising technique in medical imaging. We consider a
numerical example which consists in finding the position and size of a
non-conductive region inside a conductive wire. We review the electric
impedance tomography inverse problem modeled by the minimization of an error
functional. To solve the boundary value problem that arises in the direct
problem, we use the boundary element method. The simulated annealing algorithm
is chosen as the optimization method. Numerical tests show the technique is
accurate to retrieve the non-conductive inclusion.


title:
A Quantum Version of The Spectral Decomposition Theorem of Dynamical
  Systems, Quantum Chaos Hierarchy: Ergodic, Mixing and Exact

abstract:
  In this paper we study Spectral Decomposition Theorem [1] and translate it to
quantum language by means of the Wigner transform. We obtain a quantum version
of Spectral Decomposition Theorem (QSDT) which enables us to achieve three
distinct goals: First, to rank Quantum Ergodic Hierarchy levels [2,3]. Second,
to analyze the classical limit in quantum ergodic systems and quantum mixing
systems. And third, and maybe most important feature, to find a relevant and
simple connection between the first three levels of quantum ergodic hierarchy
(ergodic, exact and mixing) and quantum spectrum. Finally, we illustrate the
physical relevance of QSDT applying it to two examples: Microwave billiards
[4,5] and a phenomenological Gamow model type [6,7].


title: Conformal Symmetry, Confinement, and Light-Front Holographic QCD

abstract:
  We show that (a) the conformal properties of Anti-de Sitter (AdS) space, (b)
the properties of a field theory in one dimension under the full conformal
group found by de Alfaro, Fubini and Furlan, and (c) the frame-independent
single-variable light-front Schr\"odinger equation for bound states all lead to
the same result: a relativistic nonperturbative model which successfully
incorporates salient features of hadronic physics, including confinement,
linear Regge trajectories, and results which are conventionally attributed to
spontaneous chiral symmetry breaking.


title: 3j-symbol for the modular double of SL_q(2,R) revisited

abstract:
  Modular double of quantum group SL_q(2,R) with |q|=1 has a series of
selfadjoint irreducible representations parameterized by s. Ponsot and Teschner
considered a decomposition of the tensor product of two representations into
irreducibles. In our paper we give more detailed derivation and some new
proofs.


title: Sparse Fault-Tolerant BFS Trees

abstract:
  This paper addresses the problem of designing a sparse {\em fault-tolerant}
BFS tree, or {\em FT-BFS tree} for short, namely, a sparse subgraph $T$ of the
given network $G$ such that subsequent to the failure of a single edge or
vertex, the surviving part $T'$ of $T$ still contains a BFS spanning tree for
(the surviving part of) $G$. Our main results are as follows. We present an
algorithm that for every $n$-vertex graph $G$ and source node $s$ constructs a
(single edge failure) FT-BFS tree rooted at $s$ with $O(n \cdot
\min\{\Depth(s), \sqrt{n}\})$ edges, where $\Depth(s)$ is the depth of the BFS
tree rooted at $s$. This result is complemented by a matching lower bound,
showing that there exist $n$-vertex graphs with a source node $s$ for which any
edge (or vertex) FT-BFS tree rooted at $s$ has $\Omega(n^{3/2})$ edges. We then
consider {\em fault-tolerant multi-source BFS trees}, or {\em FT-MBFS trees}
for short, aiming to provide (following a failure) a BFS tree rooted at each
source $s\in S$ for some subset of sources $S\subseteq V$. Again, tight bounds
are provided, showing that there exists a poly-time algorithm that for every
$n$-vertex graph and source set $S \subseteq V$ of size $\sigma$ constructs a
(single failure) FT-MBFS tree $T^*(S)$ from each source $s_i \in S$, with
$O(\sqrt{\sigma} \cdot n^{3/2})$ edges, and on the other hand there exist
$n$-vertex graphs with source sets $S \subseteq V$ of cardinality $\sigma$, on
which any FT-MBFS tree from $S$ has $\Omega(\sqrt{\sigma}\cdot n^{3/2})$ edges.
Finally, we propose an $O(\log n)$ approximation algorithm for constructing
FT-BFS and FT-MBFS structures. The latter is complemented by a hardness result
stating that there exists no $\Omega(\log n)$ approximation algorithm for these
problems under standard complexity assumptions.


title:
Constructing isothermal curvature line coordinates on surfaces which
  admit them

abstract:
  Isothermic parameterizations} are synonyms of isothermal curvature line
parameterizations, for surfaces immersed in Euclidean spaces. We provide a
method of constructing isothermic coordinate charts on surfaces which admit
them, starting from an arbitrary chart. One of the primary applications of this
work consists of numerical algorithms for surface visualization.


title:
Observational Quantification of the Energy Dissipated by Alfv\'en Waves
  in a Polar Coronal Hole: Evidence that Waves Drive the Fast Solar Wind

abstract:
  We present a measurement of the energy carried and dissipated by Alfv\'en
waves in a polar coronal hole. Alfv\'en waves have been proposed as the energy
source that heats the corona and drives the solar wind. Previous work has shown
that line widths decrease with height in coronal holes, which is a signature of
wave damping, but have been unable to quantify the energy lost by the waves.
This is because line widths depend on both the non-thermal velocity v_nt and
the ion temperature T_i. We have implemented a means to separate the T_i and
v_nt contributions using the observation that at low heights the waves are
undamped and the ion temperatures do not change with height. This enables us to
determine the amount of energy carried by the waves at low heights, which is
proportional to v_nt. We find the initial energy flux density present was 6.7
+/- 0.7 x 10^5 erg cm^-2 s^-1, which is sufficient to heat the coronal hole and
acccelerate the solar wind during the 2007 - 2009 solar minimum. Additionally,
we find that about 85% of this energy is dissipated below 1.5 R_sun,
sufficiently low that thermal conduction can transport the energy throughout
the coronal hole, heating it and driving the fast solar wind. The remaining
energy is roughly consistent with what models show is needed to provide the
extended heating above the sonic point for the fast solar wind. We have also
studied T_i, which we found to be in the range of 1 - 2 MK, depending on the
ion species.


title:
Bias dependent features in spin transport as a probe of the conduction
  band minima in Si

abstract:
  Unusual features in the bias dependence of spin transport are observed in a
Co/Au/NiFe spin valve fabricated on a highly textured Cu(100)/Si(100) Schottky
interface, exploiting the local probing capabilities of a Ballistic electron
magnetic microscope (BEMM). This arises due to local differences in the strain
and the presence of misfit dislocations at the Schottky interface that enhances
spin flip scattering and broadens the energy and angular distribution of the
transmitted electrons. Cumulatively, these enable the transmitted hot electrons
to probe the different conduction band minima in Si, giving rise to such bias
dependent features in the magnetocurrent. This study reveals new insights into
the spin dependence of transmission in an indirect band gap semiconductor as Si
and highlights the unique capabilities of BEMM in probing local differences in
spin transport across such textured interfaces.


title: The Cohomological Excess of Certain Moduli Spaces of Curves of Genus $g$

abstract:
  The open subvariety $\overline{M}_g^{\leq k}$ of $\overline{M}_g$
parametrizes stable curves of genus $g$ having at most $k$ rational components.
By the work of Looijenga, one expects that the cohomological excess of
$\overline{M}_g^{\leq k}$ is at most $g-1+k$. In this paper we show that when
$k=0$, the conjectured upper bound is sharp by showing that there is a
constructible sheaf on $\overline{H}_g^{\leq k}$ (the hyperelliptic locus)
which has non-vanishing cohomology in degree $3g-2$.


title:
Hilbert function spaces and the Nevanlinna-Pick problem on the polydisc
  II

abstract:
  In \cite{ds_hfs}, a geometric procedure for constructing a Nevanlinna-Pick
problem on $\D^n$ with a specified set of uniqueness was established. In this
sequel we conjecture a necessary and a sufficient condition for a
Nevanlinna-Pick problem on $\DT$ to have a unique solution. We use the results
of \cite{ds_hfs} and Bezout's theorem to establish three special cases of this
conjecture.


title: Dark Energy Models and Laws of Thermodynamics in Bianchi I Model

abstract:
  This paper is devoted to check validity of the laws of thermodynamics for LRS
Bianchi type I universe model which is filled with combination of dark matter
and dark energy. We take two types of dark energy models, i.e., generalized
holographic dark energy and generalized Ricci dark energy. It is proved that
the first and generalized second law of thermodynamics are valid on the
apparent horizon for both the models. Further, we take fixed radius $L$ of the
apparent horizon with original holographic or Ricci dark energy. We conclude
that the first and generalized second laws of thermodynamics do not hold on the
horizon of fixed radius $L$ for both the models.


title: Weierstrass traveling wave solutions for dissipative BBM equation

abstract:
  In this paper the effect of a small dissipation on waves is included to find
exact solutions to the modified BBM equation. Using Lyapunov functions and
dynamical systems theory, we prove that when viscosity is added to the BBM
equation, in certain regions there still exist bounded traveling wave solutions
in the form of solitary waves, periodic, and elliptic functions. By using the
canonical form of Abel equation, the polynomial Appell invariant make the
equation integrable in terms of Weierstrass $\wp$ functions. We will use a
general formalism based on Ince's transformation to write the general solution
of dissipative BBM in terms of $\wp$ functions, from which all the other known
solutions can be obtained via simplifying assumptions. Using ODE analysis we
show that the traveling wave speed is a bifurcation parameter that makes
transition between different classes of waves.


title:
Almost sure global well posedness for the radial nonlinear Schr\"odinger
  equation on the unit ball II: the 3D case

abstract:
  We extend the convergence method introduced in our works [8]-[10] for almost
sure global well-posedness of Gibbs measure evolutions of the nonlinear
Schr\"odinger (NLS) and nonlinear wave (NLW) equations on the unit ball in R^d
to the case of the three dimensional NLS. This is the first probabilistic
global well-posedness result for NLS with supercritical data on the unit ball
in R^3.
  The initial data is taken as a Gaussian random process lying in the support
of the Gibbs measure associated to the equation, and results are obtained
almost surely with respect to this probability measure. The key tools used
include a class of probabilistic a priori bounds for finite-dimensional
projections of the equation and a delicate trilinear estimate on the
nonlinearity, which - when combined with the invariance of the Gibbs measure -
enables the a priori bounds to be enhanced to obtain convergence of the
sequence of approximate solutions.


title:
On Castelnuovo theory and non-existence of smooth isolated curves in
  quintic threefolds

abstract:
  We give some necessary conditions for a smooth irreducible curve $C\subset
\mathbb{P}^4$ to be isolated in a smooth quintic threefold, and also find a
lower bound for $h^1(\mathcal{N}_{C/{\mathbb{P}^4}})$. Combining these with
beautiful results in Castelnuovo theory, we prove certain non-existence results
on smooth curves in smooth quintic threefolds. As an application, we can prove
Knutsen's list of examples of smooth isolated curves in general quintic
threefolds is complete up to degree 9.


title:
Symplectic Reflection Algebras in Positive Characteristic as Ore
  Extensions

abstract:
  We investigate PBW deformations H of k[x,y]#G where G is the cyclic group of
order p and k also has characteristic p; in these deformations, [x,y] takes a
value in kG. These algebras are versions of symplectic reflection algebras that
only exist in positive characteristic. They also happen to possess a
presentation as an Ore extension over a commutative subring R, and via the
derivation defining the extension, have interesting connections to certain
polynomials appearing in combinatorics and related to alternating permutations
(the Andr\'e polynomials). We find the center of these algebras, their Verma
modules, their simple modules, and the Ext groups between simples. The Verma
modules coincide with the fibers of Mod H -->> Spec R, and Mod H turns out to
be the disjoint union, in the sense of Smith and Zhang, of the Verma modules.
As in non-defining characteristic, there are some distinctions between the t=0
and t=1 cases. We also obtain results when G is replaced with an elementary
abelian p-group E: in particular, we find the center and the simple modules
when [x,y] is in k[E].


title: Entropic Forms and Related Algebras

abstract:
  Starting from a very general trace-form entropy, we introduce a pair of
algebraic structures endowed by a generalized sum and a generalized product.
These algebras form, respectively, two Abelian fields in the realm of the
complex numbers isomorphic each other. We specify our results to several
entropic forms related to distributions recurrently observed in social,
economical, biological and physical systems including the stretched
exponential, the power-law and the interpolating Bosons-Fermions distributions.
Some potential applications in the study of complex systems are advanced.


title:
Limiting geodesics for first-passage percolation on subsets of
  $\mathbb{Z}^2$

abstract:
  It is an open problem to show that in two-dimensional first-passage
percolation, the sequence of finite geodesics from any point to $(n,0)$ has a
limit in $n$. In this paper, we consider this question for first-passage
percolation on a wide class of subgraphs of $\mathbb {Z}^2$: those whose vertex
set is infinite and connected with an infinite connected complement. This
includes, for instance, slit planes, half-planes and sectors. Writing $x_n$ for
the sequence of boundary vertices, we show that the sequence of geodesics from
any point to $x_n$ has an almost sure limit assuming only existence of finite
geodesics. For all passage-time configurations, we show existence of a limiting
Busemann function. Specializing to the case of the half-plane, we prove that
the limiting geodesic graph has one topological end; that is, all its infinite
geodesics coalesce, and there are no backward infinite paths. To do this, we
prove in the Appendix existence of geodesics for all product measures in our
domains and remove the moment assumption of the Wehr-Woo theorem on absence of
bigeodesics in the half-plane.


title: Intra-Domain Pathlet Routing

abstract:
  Internal routing inside an ISP network is the foundation for lots of services
that generate revenue from the ISP's customers. A fine-grained control of paths
taken by network traffic once it enters the ISP's network is therefore a
crucial means to achieve a top-quality offer and, equally important, to enforce
SLAs. Many widespread network technologies and approaches (most notably, MPLS)
offer limited (e.g., with RSVP-TE), tricky (e.g., with OSPF metrics), or no
control on internal routing paths. On the other hand, recent advances in the
research community are a good starting point to address this shortcoming, but
miss elements that would enable their applicability in an ISP's network.
  We extend pathlet routing by introducing a new control plane for internal
routing that has the following qualities: it is designed to operate in the
internal network of an ISP; it enables fine-grained management of network paths
with suitable configuration primitives; it is scalable because routing changes
are only propagated to the network portion that is affected by the changes; it
supports independent configuration of specific network portions without the
need to know the configuration of the whole network; it is robust thanks to the
adoption of multipath routing; it supports the enforcement of QoS levels; it is
independent of the specific data plane used in the ISP's network; it can be
incrementally deployed and it can nicely coexist with other control planes.
Besides formally introducing the algorithms and messages of our control plane,
we propose an experimental validation in the simulation framework OMNeT++ that
we use to assess the effectiveness and scalability of our approach.


title: Gauge Brezis-Browder Principles and Dependent Choice

abstract:
  The gauge Brezis-Browder Principle in Turinici [Bull. Acad. Pol. Sci.
(Math.), 30 (1982), 161-166] is obtainable from the Principle of Dependent
Choices (DC) and implies Ekeland's Variational Principle (EVP); hence, it is
equivalent with both (DC) and (EVP). This is also true for the gauge
variational principle deductible from it, including the one in Bae, Cho, and
Kim [Bull. Korean Math. Soc. 48 (2011), 1023-1032].


title:
Have we found conclusive evidence for dark matter through direct
  detection experiments?

abstract:
  We employ a SUSY-model-independent method to examine the remaining evidence
for the low mass dark matter. Using the XENON100's recent result of 224.6 live
days $\times$ 34kg exposure and PICASSO's result published in 2009, we have
obtained a constrain of couplings, $\| {{a_n}} \| < 0.6$ and $\| {{a_p}} \| <
1.0$, corresponding to the spin-dependent cross section of ${\sigma_n} < 5.6
\times {10^{- 38}}$cm$^{2}$ and ${\sigma_p} < 1.6 \times {10^{- 37}}$cm$^{2}$.
Spin-independent isospin violating dark matter model also failed to reconcile
the recent result from XENON100 with the positive results from DAMA and CoGeNT.


title:
An Ontology Construction Approach for the Domain Of Poultry Science
  Using Protege

abstract:
  The information retrieval systems that are present nowadays are mainly based
on full text matching of keywords or topic based classification. This matching
of keywords often returns a large number of irrelevant information and this
does not meet the users query requirement. In order to solve this problem and
to enhance the search using semantic environment, a technique named ontology is
implemented for the field of poultry in this paper. Ontology is an emerging
technique in the current field of research in semantic environment. This paper
constructs ontology using the tool named Protege version 4.0 and this also
generates Resource Description Framework schema and XML scripts for using
poultry ontology in web.


title:
Failure of the Bell Locality Condition over a Space of Ideal Particles
  and their Paths

abstract:
  We construct a space of ideal elements (particles and their paths) to analyze
certain aspects of quantum physics. The particles are taken from a model of
particle interaction first described by David Deutsch (based on a different but
related framework, that of MWI), and the paths are based on Richard Feynman's
path-integral formulation of quantum mechanics. By combining the two systems we
develop a new approach to quantum mechanics that eliminates various quantum
paradoxes.


title: Extended geometry and gauged maximal supergravity

abstract:
  We consider generalized diffeomorphisms on an extended mega-space associated
to the U-duality group of gauged maximal supergravity in four dimensions, E_7.
Through the bein for the extended metric we derive dynamical (field-dependent)
fluxes taking values in the representations allowed by supersymmetry, and
obtain their quadratic constraints from gauge consistency conditions. A
covariant generalized Ricci tensor is introduced, defined in terms of a
connection for the generalized diffeomorphisms. We show that for any
torsionless and metric-compatible generalized connection, the Ricci scalar
reproduces the scalar potential of gauged maximal supergravity. We comment on
how these results extend to other groups and dimensions.


title: A Comparative Study of AGN Feedback Algorithms

abstract:
  Modelling AGN feedback in numerical simulations is both technically and
theoretically challenging, with numerous approaches having been published in
the literature. We present a study of five distinct approaches to modelling AGN
feedback within gravitohydrodynamic simulations of major mergers of Milky
Way-sized galaxies. To constrain differences to only be between AGN feedback
models, all simulations start from the same initial conditions and use the same
star formation algorithm. Most AGN feedback algorithms have five key aspects:
black hole accretion rate, energy feedback rate and method, particle accretion
algorithm, black hole advection algorithm, and black hole merger algorithm. All
models follow different accretion histories, with accretion rates that differ
by up to three orders of magnitude at any given time. We consider models with
either thermal or kinetic feedback, with the associated energy deposited
locally around the black hole. Each feedback algorithm modifies the gas
properties near the black hole to different extents. The particle accretion
algorithms usually (but not always) maintain good agreement between the mass
accreted by \dot{M} dt and the mass of gas particles removed from the
simulation. The black hole advection algorithms dampen inappropriate dragging
of the black holes by two-body interactions. Advecting the black hole a limited
distance based upon local mass distributions has many desirably properties. The
black holes merge when given criteria are met, and we find a range of merger
times for different criteria. Using the M_{BH}-\sigma relation as a diagnostic
of the remnants yields three models that lie within the one-sigma scatter of
the observed relation and two that fall below it. The wide variation in
accretion behaviours of the models reinforces the fact that there remains much
to be learnt about the evolution of galactic nuclei. (abridged)


title: The Mid-Infrared and Optical Decay of SN 2011fe

abstract:
  We measure the decay rate of the mid-IR luminosity from type Ia supernova
2011fe between six months and one year after explosion using Spitzer/IRAC
observations. The fading in the 3.6 micron channel is 1.48+/-0.02 mag/100d,
which is similar to that seen in blue optical bands. The supernova brightness
fades at 0.78+/-0.02 mag/100d in the 4.5 micron channel which is close to that
observed in the near-IR. We argue that the difference is a result of doubly
ionized iron-peak elements dominating the bluer IRAC band while singly ionized
species are controlling the longer wavelength channel. To test this, we use
Large Binocular Telescope spectra taken during the same phases to show that
doubly ionized emission lines do fade more slowly than their singly ionized
cousins. We also find that [Co III] emission fades at more than twice the
radioactive decay rate due to the combination of decreasing excitation in the
nebula, recombination and cobalt decaying to iron. The nebular emission
velocities of [Fe III] and [Co III] lines show a smaller blue-shift than
emission from singly ionized atoms. The Si II velocity gradient near maximum
light combined with our nebular velocity measurements suggest SN 2011fe was a
typical member of the `low velocity gradient' class of type Ia. Analyzing IRAC
photometry from other supernovae we find that mid-IR color of type Ia events is
correlated with the early light curve width and can be used as an indicator of
the radioactive nickel yield.


title: Discovery of Fourier-dependent time lags in cataclysmic variables

abstract:
  We report the first study of Fourier-frequency-dependent coherence and
phase/time lags at optical wavelengths of cataclysmic variables (MV Lyr and LU
Cam) displaying typical flickering variability in white light. Observations
were performed on the William Herschel Telescope using ULTRACAM. Lightcurves
for both systems have been obtained with the SDSS filters $u'$, $g'$ and $r'$
simultaneously with cadences between $\approx0.5-2$ seconds, and allow us to
probe temporal frequencies between ~10^{-3} Hz and ~1 Hz. We find high levels
of coherence between the u', g' and r' lightcurves up to at least ~10^{-2} Hz.
Furthermore we detect red/negative lags where the redder bands lag the bluer
ones at the lowest observed frequencies. For MV Lyr time lags up to ~3 seconds
are observed, whilst LU Cam displays larger time lags of ~10 seconds.
Mechanisms which seek to explain red/negative lags observed in X-ray binaries
and Active Galactic Nuclei involve reflection of photons generated close to the
compact object onto the surface layers of the accretion disk, where the lag
delay is simply the light-travel time from the emitting source to the
reflecting accretion disk area. Although this could be a viable explanation for
the lags observed in MV Lyr, the lags observed in LU Cam are too large to be
explained by reflection from the disk and/or the donor star. We suggest
reprocessing on the thermal timescale of boundary layer photons onto the
accretion disk as a possible mechanism to explain the lags observed in
accreting white dwarfs, or reverse (inside-out) shocks within the disk
travelling through cooler disk regions as they move outwards.


title: Retrofitted Natural Supersymmetry from a U(1)

abstract:
  We propose that a single, spontaneously broken, U(1) gauge symmetry may be
responsible for suppressing both the first two generation Yukawa couplings, and
also, in a correlated manner, parameters in the dynamical supersymmetry (SUSY)
breaking sector by the mechanism of retrofitting. In the dynamical SUSY
breaking sector, these small parameters are typically required in order to
introduce R-symmetry breaking in a controlled manner and obtain
phenomenologically viable meta-stable vacua. The heavy U(1) multiplet mediates
a dominant contribution to the first two generation MSSM sfermion soft masses,
while gauge mediation provides a parametrically suppressed soft term
contribution to the stop and most other states, so realising a natural SUSY
spectrum in a fashion consistent with SUSY unification. In explicit models the
spectra obtained can be such that current LHC limits are evaded, and
predictions of flavour changing processes are consistent with observation. We
examine both implementations with low scale mediation, and string-motivated
examples where the U(1) is anomalous before the inclusion of a generalised
Green-Schwarz mechanism.


title:
The Bimodal Metallicity Distribution of the Cool Circumgalactic Medium
  at z<1

abstract:
  We assess the metal content of the cool (10^4 K) circumgalactic medium (CGM)
about galaxies at z<1 using an H I-selected sample of 28 Lyman limit systems
(LLS, defined here as absorbers with 16.2<log N(H I)<18.5) observed in
absorption against background QSOs by the Cosmic Origins Spectrograph on-board
the Hubble Space Telescope. The N(H I) selection avoids metallicity biases
inherent in many previous studies of the low-redshift CGM. We compare the
column densities of weakly ionized metal species (e.g., O II, Si II, Mg II) to
N(H I) in the strongest H I component of each absorber. We find that the
metallicity distribution of the LLS (and hence the cool CGM) is bimodal with
metal-poor and metal-rich branches peaking at [X/H]=-1.6 and -0.3 (or about
2.5% and 50% solar metallicities). The cool CGM probed by these LLS is
predominantly ionized. The metal-rich branch of the population likely traces
winds, recycled outflows, and tidally stripped gas; the metal-poor branch has
properties consistent with cold accretion streams thought to be a major source
of fresh gas for star forming galaxies. Both branches have a nearly equal
number of absorbers. Our results thus demonstrate there is a significant mass
of previously-undiscovered cold metal-poor gas and confirm the presence of
metal enriched gas in the CGM of z<1 galaxies.


title: Generalised Moonshine and Holomorphic Orbifolds

abstract:
  Generalised moonshine is reviewed from the point of view of holomorphic
orbifolds, putting special emphasis on the role of the third cohomology group
H^3(G, U(1)) in characterising consistent constructions. These ideas are then
applied to the case of Mathieu moonshine, i.e. the recently discovered
connection between the largest Mathieu group M_24 and the elliptic genus of K3.
In particular, we find a complete list of twisted twining genera whose modular
properties are controlled by a class in H^3(M_24, U(1)), as expected from
general orbifold considerations.


title: Superconducting Dome from Holography

abstract:
  We find a regime in which a strongly coupled striped superconductor features
a superconducting dome. This regime is signified by i) a modulating chemical
potential that averages to zero, and ii) a superconducting order parameter that
has a scaling dimension larger than 3/2 but less than or equal to 3. We also
find that in this regime, the order parameter exhibits a mild dependence on the
modulation wavelength of the stripe.


title:
Doublon-holon binding, Mott transition, and fractionalized
  antiferromagnet in the Hubbard model

abstract:
  We argue that the binding between doubly occupied (doublon) and empty (holon)
sites governs the incoherent excitations and plays a key role in the Mott
transition in strongly correlated Mott-Hubbard systems. We construct a new
saddle point solution with doublon-holon binding in the Kotliar-Ruckenstein
slave-boson functional integral formulation of the Hubbard model. On the
half-filled honeycomb lattice and square lattice, the ground state is found to
exhibit a continuous transition from the paramagnetic semimetal/metal to an
antiferromagnetic ordered Slater insulator with coherent quasiparticles at
$U_{c1}$, followed by a Mott transition into an electron-fractionalized AF$^*$
phase without coherent excitations at $U_{c2}$. Such a phase structure appears
generic of bipartite lattices without frustration. We show that doublon-holon
binding unites the three important ideas of strong correlation: the coherent
quasiparticles, the incoherent Hubbard bands, and the deconfined Mott
insulator.


title: Firewalls in AdS/CFT

abstract:
  Several recent papers argue against firewalls by relaxing the requirement for
locality outside the stretched horizon. In the firewall argument, locality
essentially serves the purpose of ensuring that the degrees of freedom required
for infall are those in the proximity of the black hole and not the ones in the
early radiation. We make the firewall argument sharper by utilizing the AdS/CFT
framework and claim that the firewall argument essentially states that the dual
to a thermal state in the CFT is a firewall.


title: Zigzag Phase Transition in Quantum Wires

abstract:
  We study the quantum phase transition of interacting electrons in quantum
wires from a one-dimensional (1D) linear configuration to a quasi-1D zigzag
arrangement using quantum Monte Carlo methods. As the density increases from
its lowest values, first, the electrons form a linear Wigner crystal; then, the
symmetry about the axis of the wire is broken as the electrons order in a
quasi-1D zigzag phase; and, finally, the electrons form a disordered
liquid-like phase. We show that the linear to zigzag phase transition is not
destroyed by the strong quantum fluctuations present in narrow wires; it has
characteristics which are qualitatively different from the classical
transition.


title:
A multiwavelength study of the Magellanic-type galaxy NGC 4449 - I.
  Modelling the spectral energy distribution, the ionization structure and the
  star formation history

abstract:
  [Abridged] We present an integrated photometric spectral energy distribution
(SED) of the Magellanic-type galaxy NGC 4449 from the far-ultraviolet (UV) to
the submillimetre, including new observations acquired by the Herschel Space
Observatory. We include integrated UV photometry from the Swift Ultraviolet and
Optical Telescope using a measurement technique which is appropriate for
extended sources with coincidence loss. In this paper, we examine the available
multiwavelength data to infer a range of ages, metallicities and star formation
rates for the underlying stellar populations, as well as the composition and
the total mass of dust in NGC 4449.
  We present an iterative scheme, which allows us to build an in-depth and
multicomponent representation of NGC 4449 `bottom-up', taking advantage of the
broad capabilities of the photoionization and radiative transfer code MOCASSIN
(MOnte CArlo SimulationS of Ionized Nebulae). We fit the observed SED, the
global ionization structure and the emission line intensities, and infer a
recent SFR of 0.4 Msolar/yr and a total stellar mass of approximately 1e9
Msolar emitting with a bolometric luminosity of 5.7e9 Lsolar. Our fits yield a
total dust mass of 2.9e6 Msolar including 2 per cent attributed to polycyclic
aromatic hydrocarbons. We deduce a dust to gas mass ratio of 1/190 within the
modelled region. While we do not consider possible additional contributions
from even colder dust, we note that including the extended HI envelope and the
molecular gas is likely to bring the ratio down to as low as ~ 1/800.


title:
Direct observation of the Mott gap in strontium iridate with a scanning
  tunneling microscope

abstract:
  The single-layer Mott insulator strontium iridate Sr$_2$IrO$_4$ was studied
using a scanning tunneling microscope. This measurement technique is unique due
to the transport properties of this Mott insulator allowing tunneling
measurements to be performed, even at cryogenic temperatures. We obtained
high-resolution images of the sample surface and the differential tunneling
conductance at different cryogenic temperatures. The differential conductance
is a direct measurement of the local electronic density of states which
provided an insulating gap consistent with optical conductivity, angle resolved
photoemission spectroscopy and resonant inelastic x-ray scattering (RIXS)
experiments. The observed widths of these features is broader than predicted by
the Slater approximation and narrower than predicted by dynamical mean field
theory. Additionally, the observed density of states due to magnetic
fluctuations is found in the derivative of the differential conductance and is
consistent with results from Raman scattering and RIXS. At low temperatures,
additional low-energy features were observed, suggesting a change in the
dispersion of the collective magnetic excitations, which is consistent with the
magnetic susceptibility.


title: Performing a stellar autopsy using the radio-bright remnant of SN 1996cr

abstract:
  We present archival radio observations of SN1996cr from ATCA and MOST, and
model its radio lightcurves using X-ray constrained hydrodynamical simulations
of the interaction between the SN ejecta and the CSM. The early radio data show
signs of free-free absorption (FFA), which decreases gradually and is minimal
above 1.4 GHz after day ~3000. FFA optical depth constraints provide estimates
of the CSM free electron density, which allows insight into the ionisation of
SN1996cr's CSM and offers a test on the density distribution adopted by the
hydrodynamical simulation. The intrinsic spectral index of the radiation shows
evidence for spectral flattening, which is characterised by alpha = 0.852 +/-
0.002 at day 3000 and a decay rate of d_alpha = -0.014 +/- 0.001 yr^-1. The
similarity in the spectral flattening of SN1987A, SN1993J, and SN1996cr
suggests this may be a relatively common feature of SNe/CSM shocks. We adopt
this spectral index variation to model the synchrotron radio emission of the
shock, and consider several scalings that relate the parameters of the
hydrodynamical simulation to the magnetic field and electron distribution. The
simulated light curves match the large-scale features of the observed light
curves, but fail to match certain tightly constraining sections. This suggests
that simple energy density scalings may not be able to account for the
complexities of the true physical processes at work, or alternatively, that the
parameters of the simulation require modification in order to accurately
represent SN1996cr's CSM.


title:
Majorana Fermions in Semiconductor Nanowires: Fundamentals, Modeling,
  and Experiment

abstract:
  After a recent series of rapid and exciting developments, the long search for
the Majorana fermion - the elusive quantum entity at the border between
particles and antiparticles - has produced the first positive experimental
results, but is not over yet. Originally proposed by E. Majorana in the context
of particle physics, Majorana fermions have a condensed matter analog in the
zero-energy bound states emerging in topological superconductors. A promising
route to engineering topological superconductors capable of hosting Majorana
zero modes consists of proximity coupling semiconductor thin films or nanowires
with strong spin-orbit interaction to conventional s-wave superconductors in
the presence of an external Zeeman field. The Majorana zero mode is predicted
to emerge above a certain critical Zeeman field as a zero-energy state
localized near the order parameter defects, viz., vortices for thin films and
wire-ends for the nanowire. These Majorana bound states are expected to
manifest non--Abelian quantum statistics, which makes them ideal building
blocks for fault--tolerant topological quantum computation. This review
provides an update on current status of the search for Majorana fermions in
semiconductor nanowires by focusing on the recent developments, in particular
the period following the first reports of experimental signatures consistent
with the realization of Majorana bound states in semiconductor
nanowire--superconductor hybrid structures. We start with a discussion of the
fundamental aspects of the subject, followed by considerations on the realistic
modeling which is a critical bridge between theoretical predictions based on
idealized conditions and the real world, as probed experimentally. The last
part is dedicated to a few intriguing issues that were brought to the fore by
the recent encouraging experimental advances.


title:
Higher-Loop Calculations of the Ultraviolet to Infrared Evolution of a
  Vectorial Gauge Theory in the Limit $N_c \to \infty$, $N_f \to \infty$ with
  $N_f/N_c$ Fixed

abstract:
  We consider an asymptotically free vectorial SU($N_c$) gauge theory with
$N_f$ fermions in the fundamental representation and analyze higher-loop
contributions to the evolution of the theory from the ultraviolet to the
infrared in the limit where $N_c \to \infty$ and $N_f \to \infty$ with
$r=N_f/N_c$ a fixed, finite constant. We focus on the case where the $n$-loop
beta function has an infrared zero, at $\xi=\xi_{IR,n\ell}$, where $\xi=\alpha
N_c$. We give results on $\xi_{IR,n\ell}$, the anomalous dimension of the
fermion bilinear evaluated at $\xi_{IR,n\ell}$, denoted $\gamma_{IR,n\ell}$,
and certain structural properties of the beta function, $\beta_\xi$. The
approach to this limit is investigated, and it is shown that the leading
correction terms are strongly suppressed, by the factor $1/N_c^2$. This
provides an understanding of a type of approximate universality in calculations
for moderate values of $N_c$ and $N_f$, namely that $\alpha_{IR,n\ell}N_c$,
$\gamma_{IR,n\ell}$, and structural properties of the beta function are similar
in theories with different values of $N_c$ and $N_f$ provided that they have
similar values of $N_f/N_c$. We give results up to four loops for
nonsupersymmetric theories and up to three loops for supersymmetric theories.


title: A Super-Solar Metallicity for the Progenitor of Kepler's Supernova

abstract:
  We have performed deep X-ray observations of the remnant of Kepler's
supernova (SN 1604) as a Key Project of the Suzaku Observatory. Our main goal
is to detect secondary Fe-peak elements in the SN ejecta to gain insights into
the Type Ia supernova explosion mechanism and the nature of the progenitor.
Here we report our initial results. We made a conclusive detection of X-ray
emission lines from highly ionized Mn, Cr, and Ni as well as Fe. The observed
Mn-to-Cr line flux ratio is ~0.60, ~30% larger than that measured in Tycho's
remnant. We estimate a Mn-to-Cr mass ratio of ~0.77, which is strongly
suggestive of a large neutron excess in the progenitor star before the onset of
the thermonuclear runaway. The observed Ni-to-Fe line flux ratio (~0.03)
corresponds to a mass ratio of ~0.06, which is generally consistent with the
products of explosive Si-burning regime in Type Ia explosion models, and rules
out contamination from the products of neutron-rich nuclear statistical
equilibrium in the shocked ejecta. Together with the previously suggested
luminous nature of the explosion, these mass ratios provide strong evidence for
a super-solar metallicity in the SN progenitor (~3 Z_sun). Kepler's supernova
was likely the thermonuclear explosion of a white dwarf formed in the recent
past that must have exploded through a relatively prompt channel.


title:
Bond percolation on a non-p.c.f. Sierpi\'nski Gasket, iterated
  barycentric subdivision of a triangle, and Hexacarpet

abstract:
  We investigate bond percolation on the iterated barycentric subdivision of a
triangle, the hexacarpet, and the non-p.c.f. Sierpinski gasket. With the use of
the diamond fractal, we are able to bound the critical probability of
percolation on the non-p.c.f. gasket and the iterated barycentric subdivision
of a triangle from above by 0.282. We then show how both the gasket and
hexacarpet fractals are related via the iterated barycentric subdivisions of a
triangle: the two spaces exhibit duality properties although they are not
themselves dual graphs. Finally we show the existence of a non-trivial phase
transition on all three graphs.


title: NLO Uncertainties in Higgs + 2 jets from Gluon Fusion

abstract:
  A central ingredient in establishing the properties of the newly discovered
Higgs-like boson is to isolate its production via vector boson fusion (VBF).
With the typical experimental selection cuts, the VBF sample is contaminated by
a 25% fraction from Higgs + 2 jet production via gluon fusion (ggF) which has
large perturbative uncertainties. We perform a detailed study of the
perturbative uncertainties in the NLO predictions for pp -> H+2 jets via ggF
used by the ATLAS and CMS collaborations, with the VBF selection cuts of their
current H -> gamma gamma analyses. We discuss in detail the application of the
so-called "ST method" for estimating fixed-order perturbative uncertainties in
this case, and also consider generalizations of it. Qualitatively, our results
apply equally to other decay channels with similar VBF selection cuts. Typical
VBF selections include indirect restrictions or explicit vetoes on additional
jet activity, primarily to reduce non-Higgs backgrounds. We find that such
restrictions have to be chosen carefully and are not necessarily beneficial for
the purpose of distinguishing between the VBF and ggF production modes, since a
modest reduction in the relative ggF contamination can be easily overwhelmed by
its quickly increasing perturbative uncertainties.


title:
X-ray emission from RX J1720.1+2638 and Abell 267: a comparison between
  a fossil and a non-fossil system

abstract:
  We present the XMM-Newton X-ray analysis of RXJ1720.1+2638 and Abell267, a
non-fossil and a fossil system, respectively. The whole spectrum of both
objects can be explained by thermal emission. The luminosities found for
RXJ1720.1+2638 and Abell267 in the 2-10 keV band are
6.20^{+0.04}_{-0.02}\times10^{44} and 3.90^{+0.10}_{-0.11}\times10^{44} cgs,
respectively. The radial profiles show a cool core nature for the non-fossil
system RXJ1720.1+2638, while Abell267 shows a constant behaviour of temperature
with radius. Metallicity profiles have also been produced, but no evidence of
any gradient was detected due to the large uncertainties in the determination
of this parameter. Finally, density and mass profiles were also produced
allowing to derive M_500 for RXJ1720.1+2638 and Abell267. The masses obtained
are high, in the range of (5-7)10^{14}\,M_{\odot}. The X-ray properties
obtained for both systems are not always in good agreement with what is
expected: cool cores are expected for fossil systems, as Abell267, considering
them as and relaxed systems. However, the decrement of the temperature in
Abell267 could start at lower radii. Also the presence of a recent merger in
Abell267, already suggested in the literature, could have increased the central
temperature. The non-fossil system RXJ1720.1+2638 actually exhibits a cool core
profile, but also evidence of a recent merger has been reported.


title:
Long-term monitoring of PKS 0537-441 with Fermi-LAT and multiwavelength
  observations

abstract:
  We report on multiwavelength observations of the blazar PKS 0537-441 (z =
0.896) obtained from microwaves through gamma rays by SMA, REM, ATOM, Swift and
Fermi during 2008 August-2010 April. Strong variability has been observed in
gamma rays, with two major flaring episodes (2009 July and 2010 March) and a
harder-when-brighter behaviour, quite common for FSRQs and
low-synchrotron-peaked BL Lacs, in 2010 March. In the same way the SED of the
source cannot be modelled by a simple synchrotron self-Compton model, as
opposed to many BL Lacs, but the addition of an external Compton component of
seed photons from a dust torus is needed. The 230 GHz light curve showed an
increase simultaneous with the gamma-ray one, indicating co-spatiality of the
mm and gamma-ray emission region likely at large distance from the central
engine. The low, average, and high activity SED of the source could be fit
changing only the electron distribution parameters, but two breaks in the
electron distribution are necessary. The ensuing extra spectral break, located
at NIR-optical frequencies, together with that in gamma rays seem to indicate a
common origin, most likely due to an intrinsic feature in the underlying
electron distribution. An overall correlation between the gamma-ray band with
the R-band and K-band has been observed with no significant time lag. On the
other hand, when inspecting the light curves on short time scales some
differences are evident. In particular, flaring activity has been detected in
NIR and optical bands with no evident gamma-ray counterparts in 2009 September
and November. Moderate variability has been observed in X-rays with no
correlation between flux and photon index. An increase of the detected X-ray
flux with no counter part at the other wavelengths has been observed in 2008
October, suggesting once more a complex correlation between the emission at
different energy bands.


title: High-Field Electrical and Thermal Transport in Suspended Graphene

abstract:
  We study the intrinsic transport properties of suspended graphene devices at
high fields (>1 V/um) and high temperatures (>1000 K). Across 15 samples, we
find peak (average) saturation velocity of 3.6x10^7 cm/s (1.7x10^7 cm/s), and
peak (average) thermal conductivity of 530 W/m/K (310 W/m/K), at 1000 K. The
saturation velocity is 2-4 times and the thermal conductivity 10-17 times
greater than in silicon at such elevated temperatures. However, the thermal
conductivity shows a steeper decrease at high temperature than in graphite,
consistent with stronger effects of second-order three-phonon scattering. Our
analysis of sample-to-sample variation suggests the behavior of "cleaner"
devices most closely approaches the intrinsic high-field properties of
graphene. This study reveals key features of charge and heat flow in graphene
up to device breakdown at ~2230 K in vacuum, highlighting remaining unknowns
under extreme operating conditions.


title:
Shooting with degree theory: Analysis of some weighted poly-harmonic
  systems

abstract:
  In this paper, the author establishes the existence of positive entire
solutions to a general class of semilinear poly-harmonic systems, which
includes equations and systems of the weighted Hardy--Littlewood--Sobolev type.
The novel method used implements the classical shooting method enhanced by
topological degree theory. The key steps of the method are to first construct a
target map which aims the shooting method and the non-degeneracy conditions
guarantee the continuity of this map. With the continuity of the target map, a
topological argument is used to show the existence of zeros of the target map.
The existence of zeros of the map along with a non-existence theorem for the
corresponding Navier boundary value problem imply the existence of positive
solutions for the class of poly-harmonic systems.


title: Are Yao Graph and Theta Graph Void Free?

abstract:
  Greedy Forwarding algorithm is a widely-used routing algorithm for wireless
networks. However, it can fail if network topologies (usually modeled by
geometric graphs) contain voids. Since Yao Graph and Theta Graph are two types
of geometric graphs exploited to construct wireless network topologies, this
paper studies whether these two types of graphs can contain voids.
Specifically, this paper shows that when the number of cones in a Yao Graph or
Theta Graph is less than 6, Yao Graph and Theta Graph can have voids, but when
the number of cones equals or exceeds 6, Yao Graph and Theta Graph are free of
voids.


title: Speeding Up Network Simulations Using Discrete Time

abstract:
  We develop a way of simulating disease spread in networks faster at the cost
of some accuracy. Instead of a discrete event simulation (DES) we use a
discrete time simulation. This aggregates events into time periods. We prove a
bound on the accuracy attained. We also discuss the choice of step size and do
an analytical comparison of the computational costs. Our error bound concept
comes from the theory of numerical methods for SDEs and the basic proof
structure comes from the theory of numerical methods for ODEs.


title: Why multi-tracer surveys beat cosmic variance

abstract:
  Galaxy surveys that map multiple species of tracers of large-scale structure
can improve the constraints on some cosmological parameters far beyond the
limits imposed by a simplistic interpretation of cosmic variance. This
enhancement derives from comparing the relative clustering between different
tracers of large-scale structure. We present a simple but fully generic
expression for the Fisher information matrix of surveys with any (discrete)
number of tracers, and show that the enhancement of the constraints on
bias-sensitive parameters are a straightforward consequence of this
multi-tracer Fisher matrix. In fact, the relative clustering amplitudes between
tracers are eigenvectors of this multi-tracer Fisher matrix. The diagonalized
multi-tracer Fisher matrix clearly shows that while the effective volume is
bounded by the physical volume of the survey, the relational information
between species is unbounded. As an application, we study the expected
enhancements in the constraints of realistic surveys that aim at mapping
several different types of tracers of large-scale structure. The gain obtained
by combining multiple tracers is highest at low redshifts, and in one
particular scenario we analyzed, the enhancement can be as large as a factor of
~3 for the accuracy in the determination of the redshift distortion parameter,
and a factor ~5 for the local non-Gaussianity parameter. Radial and angular
distance determinations from the baryonic features in the power spectrum may
also benefit from the multi-tracer approach.


title: Thrifty Algorithms for Multistage Robust Optimization

abstract:
  We consider a class of multi-stage robust covering problems, where additional
information is revealed about the problem instance in each stage, but the cost
of taking actions increases. The dilemma for the decision-maker is whether to
wait for additional information and risk the inflation, or to take early
actions to hedge against rising costs. We study the "k-robust" uncertainty
model: in each stage i = 0, 1,...,T, the algorithm is shown some subset of size
k_i that completely contains the eventual demands to be covered; here k_1 > k_2
>...> k_T which ensures increasing information over time. The goal is to
minimize the cost incurred in the worst-case possible sequence of revelations.
  For the multistage k-robust set cover problem, we give an O(log m + log
n)-approximation algorithm, nearly matching the \Omega(log n + log m/loglog m)
hardness of approximation even for T=2 stages. Moreover, our algorithm has a
useful "thrifty" property: it takes actions on just two stages. We show similar
thrifty algorithms for multi-stage k-robust Steiner tree, Steiner forest, and
minimum-cut. For these problems our approximation guarantees are O(min{T, log
n, log L_{max}), where L_{max} is the maximum inflation over all the stages. We
conjecture that these problems also admit O(1)-approximate thrifty algorithms.


title:
Vapnik-Chervonenkis density on indiscernible sequences, stability, and
  the maximum property

abstract:
  This paper presents some finite combinatorics of set systems with
applications to model theory, particularly the study of dependent theories.
There are two main results. First, we give a way of producing lower bounds on
VC_ind-density, and use it to compute the exact VC_ind- density of polynomial
inequalities, and a variety of geometric set families. The main technical tool
used is the notion of a maximum set system, which we juxtapose to
indiscernibles. In the second part of the paper we give a maximum set system
analogue to Shelah's characterization of stability using indiscernible
sequences.


title: Bulk viscosity coefficients due to phonons in superfluid neutron stars

abstract:
  We calculate the three bulk viscosity coefficients as arising from the
collisions among phonons in superfluid neutron stars. We use effective field
theory techniques to extract the allowed phonon collisional processes, written
as a function of the equation of state of the system. The solution of the
dynamical evolution of the phonon number density allows us to calculate the
bulk viscosity coefficients as function of the phonon collisional rate and the
phonon dispersion law, which depends on the neutron pairing gap. Our method of
computation is rather general, and could be used for different superfluid
systems, provided they share the same underlying symmetries. We find that the
behavior with temperature of the bulk viscosity coefficients is dominated by
the contributions coming from the collinear regime of the $2\leftrightarrow3$
phonon processes. For typical star radial pulsation frequencies of $\omega \sim
10^{4} s^{-1}$, we obtain that the bulk viscosity coefficients at densities $n
\gtrsim 4n_0$ are within 10% from its static value for $T \lesssim 10^9 K$ and
for the case of strong neutron superfluidity in the core with a maximum value
of the $^3P_2$ gap above 1 MeV, while, otherwise, the static solution is not a
valid approximation to the bulk viscosity coefficients. Compared to previous
results from Urca and modified Urca reactions, we conclude that at $T\sim
10^9$K phonon collisions give the leading contribution to the bulk viscosities
in the core of the neutron stars, except for $n \sim 2n_0$ when the opening of
the Urca processes takes place.


title:
On the stationary Navier-Stokes flow with isotropic streamlines in all
  latitudes on a sphere or a 2D hyperbolic space

abstract:
  In this paper, we show the existence of real-analytic stationary
Navier-Stokes flows with isotropic streamlines in all latitudes in some
simply-connected flow region on a rotating round sphere. We also exclude the
possibility of having a Poiseuille's flow profile to be one of these stationary
Navier-Stokes flows with isotropic streamlines. When the sphere is replaced by
a 2-dimensional hyperbolic space, we also give the analog existence result for
stationary parallel laminar Navier-Stokes flows along a circular-arc boundary
portion of some compact obstacle in the 2-D hyperbolic space. The existence of
stationary parallel laminar Navier-Stokes flows along a straight boundary of
some obstacle in the 2-D hyperbolic space is also studied. In any one of these
cases, we show that a parallel laminar flow with a Poiseuille's flow profile
ceases to be a stationary Navier-Stokes flow, due to the curvature of the
background manifold.


title: Nonparametric Basis Pursuit via Sparse Kernel-based Learning

abstract:
  Signal processing tasks as fundamental as sampling, reconstruction, minimum
mean-square error interpolation and prediction can be viewed under the prism of
reproducing kernel Hilbert spaces. Endowing this vantage point with
contemporary advances in sparsity-aware modeling and processing, promotes the
nonparametric basis pursuit advocated in this paper as the overarching
framework for the confluence of kernel-based learning (KBL) approaches
leveraging sparse linear regression, nuclear-norm regularization, and
dictionary learning. The novel sparse KBL toolbox goes beyond translating
sparse parametric approaches to their nonparametric counterparts, to
incorporate new possibilities such as multi-kernel selection and matrix
smoothing. The impact of sparse KBL to signal processing applications is
illustrated through test cases from cognitive radio sensing, microarray data
imputation, and network traffic prediction.


title:
Dynamic and static control of the optical phase of guided p-polarized
  light for near-field focusing at large angles of incidence

abstract:
  Both dynamic and static approaches are proposed and investigated for
controlling the optical phase of a p-polarized light wave that is guided
through a surface-patterned metallic structure with subwavelength features. For
dynamic control, field-induced transparency (FIT) from photo-excited electrons
in a slit-embedded atomic system show up within a narrow frequency window for
modulating the intensity of focused transmitted light in the near-field region.
Based on the electromagnetic coupling, this is facilitated by surface plasmons
between the two FIT-atom embedded slits. For static control, the role of
surface curvature is obtained for focused transmitted light passing through a
Gaussian-shaped metallic microlens embedded with a linear array of slits, in
addition to a negative light-refraction pattern, which is associated with
higher-diffraction modes of light, under a large angle of incidence in the
near-field region. Most interesting, however, this anomalous negative
light-refraction pattern becomes suppressible with leaked higher-order
waveguide modes of light passing through a very thin film. At the same time, it
is also suppressible with a reinforced reflection at the left foothill of a
Gaussian-shaped slit array for the forward-propagating surface-plasmon wave at
large angles of incidence. A prediction is given for near-field focusing of
light with its sharpness dynamically controlled by the frequency of the light
in a very narrow window. Moreover, a different scheme based on Green's second
integral identity is proposed for overcoming a difficulty in calculating the
near-field distribution very close to a surface by means of a
finite-difference-time-domain method.


title: Strong accessibility for finitely presented groups

abstract:
  A hierarchy of a group is a rooted tree of groups obtained by iteratively
passing to vertex groups of graphs of groups decompositions. We define a
(relative) slender JSJ hierarchy for (almost) finitely presented groups and
show that it is finite, provided the group in question doesn't contain any
slender subgroups with infinite dihedral quotients and satisfies an ascending
chain condition on certain chains of subgroups of edge groups.
  As a corollary, slender JSJ hierarchies of hyperbolic groups which are
(virtually) without $2$--torsion and finitely presented subgroups of SL(n,Z)
are both finite.


title:
The Importance of Physical Models for Deriving Dust Masses and Grain
  Size Distributions in Supernova Ejecta I: Radiatively Heated Dust in the Crab
  Nebula

abstract:
  Recent far-infrared (IR) observations of supernova remnants (SNRs) have
revealed significantly large amounts of newly-condensed dust in their ejecta,
comparable to the total mass of available refractory elements. The dust masses
derived from these observations assume that all the grains of a given species
radiate at the same temperature, regardless of the dust heating mechanism or
grain radius. In this paper, we derive the dust mass in the ejecta of the Crab
Nebula, using a physical model for the heating and radiation from the dust. We
adopt a power-law distribution of grain sizes and two different dust
compositions (silicates and amorphous carbon), and calculate the heating rate
of each dust grain by the radiation from the pulsar wind nebula (PWN). We find
that the grains attain a continuous range of temperatures, depending on their
size and composition. The total mass derived from the best-fit models to the
observed IR spectrum is 0.019-0.13 solar masses, depending on the assumed grain
composition. We find that the power-law size distribution of dust grains is
characterized by a power-law index of 3.5-4.0 and a maximum grain size larger
than 0.1 microns. The grain sizes and composition are consistent with what is
expected for dust grains formed in a Type IIP SN. Our derived dust mass is at
least a factor of two less than the mass reported in previous studies of the
Crab Nebula that assumed more simplified two-temperature models. The results of
this study show that a physical model resulting in a realistic distribution of
dust temperatures can constrain the dust properties and affect the derived dust
masses. Our study may also have important implications for deriving grain
properties and mass estimates in other SNRs and for the ultimate question of
whether SNe are major sources of dust in the Galactic interstellar medium (ISM)
and in external galaxies.


title: The Quantum Entropy Cone of Stabiliser States

abstract:
  We investigate the universal linear inequalities that hold for the von
Neumann entropies in a multi-party system, prepared in a stabiliser state. We
demonstrate here that entropy vectors for stabiliser states satisfy, in
addition to the classic inequalities, a type of linear rank inequalities
associated with the combinatorial structure of normal subgroups of certain
matrix groups.
  In the 4-party case, there is only one such inequality, the so-called
Ingleton inequality. For these systems we show that strong subadditivity, weak
monotonicity and Ingleton inequality exactly characterize the entropy cone for
stabiliser states.


title:
Statistical Approach for Predicting Factors of Mood Method for Object
  Oriented

abstract:
  Object oriented design is becoming more popular in software development and
object oriented design metrics which is an essential part of software
environment. The main goal in this paper is to predict factors of MOOD method
for OO using a statistical approach. Therefore, linear regression model is used
to find the relationship between factors of MOOD method and their influences on
OO software measurements. Fortunately, through this process a prediction could
be made for the line of code (LOC), number of classes (NOC), number of methods
(NOM), and number of attributes (NOA). These measurements permit designers to
access the software early in process, making changes that will reduce
complexity and improve the continuing capability of the design.