title: Applications of Compressed Sensing in Communications Networks

abstract:
  This paper presents a tutorial for CS applications in communications
networks. The Shannon's sampling theorem states that to recover a signal, the
sampling rate must be as least the Nyquist rate. Compressed sensing (CS) is
based on the surprising fact that to recover a signal that is sparse in certain
representations, one can sample at the rate far below the Nyquist rate. Since
its inception in 2006, CS attracted much interest in the research community and
found wide-ranging applications from astronomy, biology, communications, image
and video processing, medicine, to radar. CS also found successful applications
in communications networks. CS was applied in the detection and estimation of
wireless signals, source coding, multi-access channels, data collection in
sensor networks, and network monitoring, etc. In many cases, CS was shown to
bring performance gains on the order of 10X. We believe this is just the
beginning of CS applications in communications networks, and the future will
see even more fruitful applications of CS in our field.


title:
Anomalous Diffuse Interstellar Bands in the Spectrum of Herschel 36. I.
  Observations of Rotationally Excited CH and CH+ Absorption and Strong,
  Extended Redward Wings on Several DIBs

abstract:
  Anomalously broad diffuse interstellar bands (DIBs) at 5780.5, 5797.1,
6196.0, and 6613.6 A are found in absorption along the line of sight to
Herschel 36, the star illuminating the bright Hourglass region of the H II
region Messier 8. Interstellar absorption from excited CH+ in the J=1 level and
from excited CH in the J=3/2 level is also seen. To our knowledge, neither
those excited molecular lines nor such strongly extended DIBs have previously
been seen in absorption from interstellar gas. These unusual features appear to
arise in a small region near Herschel 36 which contains most of the neutral
interstellar material in the sight line. The CH+ and CH in that region are
radiatively excited by strong far-IR radiation from the adjacent infrared
source Her 36 SE. Similarly, the broadening of the DIBs toward Herschel 36 may
be due to radiative pumping of closely spaced high-J rotational levels of
relatively small, polar carrier molecules. If this picture of excited
rotational states for the DIB carriers is correct and applicable to most DIBs,
the 2.7 degree cosmic microwave background may set the minimum widths (about
0.35 A) of known DIBs, with molecular processes and/or local radiation fields
producing the larger widths found for the broader DIBs. Despite the intense
local UV radiation field within the cluster NGC 6530, no previously undetected
DIBs stronger than 10 mA in equivalent width are found in the optical spectrum
of Herschel 36, suggesting that neither dissociation nor ionization of the
carriers of the known DIBs by this intense field creates new carriers with
easily detectable DIB-like features. Possibly related profile anomalies for
several other DIBs are noted.


title:
Some higher order isoperimetric inequalities via the method of optimal
  transport

abstract:
  In this paper, we establish some sharp inequalities between the volume and
the integral of the $k$-th mean curvature for $k+1$-convex domains in the
Euclidean space. The results generalize the classical Alexandrov-Fenchel
inequalities for convex domains. Our proof utilizes the method of optimal
transportation.


title: Physical Design of Superconducting Magnet for ADS Injection I

abstract:
  Superconducting solenoid magnet prototype for ADS Injection I had been
designed and fabricated, and also had been tested in liquid Helium state inside
a vertical Dewar in Haerbin institute of Technology in Nov. 2012. The design
current is 210A, when the test current reached 400A no quench occurred, the
solenoid magnet was forced to quench by the embedded heaters. The integral
field strength, leakage field at the nearby upstream and downstream
superconducting spoke cavities all meet the design requirements. At the same
time, it also checked the system reliability of the vertical test Dewar and the
quenched detection system. The superconducting magnet prototype has accumulated
valuable experiences for the coming batch magnets production and cryogenic
test.


title:
Fast Linearized Alternating Direction Minimization Algorithm with
  Adaptive Parameter Selection for Multiplicative Noise Removal

abstract:
  Owing to the edge preserving ability and low computational cost of the total
variation (TV), variational models with the TV regularization have been widely
investigated in the field of multiplicative noise removal. The key points of
the successful application of these models lie in: the optimal selection of the
regularization parameter which balances the data-fidelity term with the TV
regularizer; the efficient algorithm to compute the solution. In this paper, we
propose two fast algorithms based on the linearized technique, which are able
to estimate the regularization parameter and recover the image simultaneously.
In the iteration step of the proposed algorithms, the regularization parameter
is adjusted by a special discrepancy function defined for multiplicative noise.
The convergence properties of the proposed algorithms are proved under certain
conditions, and numerical experiments demonstrate that the proposed algorithms
overall outperform some state-of-the-art methods in the PSNR values and
computational time.


title: Probing water structures in nanopores using tunneling currents

abstract:
  We study the effect of volumetric constraints on the structure and electronic
transport properties of distilled water in a nanopore with embedded electrodes.
Combining classical molecular dynamics simulations with quantum scattering
theory, we show that the structural motifs water assumes inside the pore can be
probed directly by tunneling. In particular, we show that the current does not
follow a simple exponential curve at a critical pore diameter of about 8 {\AA},
rather it is larger than the one expected from simple tunneling through a
barrier. This is due to a structural transition from bulk-like to "nanodroplet"
water domains. Our results can be tested with present experimental capabilities
to develop our understanding of water as a complex medium at nanometer length
scales.


title: C_1-cofiniteness and Fusion Products of Vertex Operator Algebras

abstract:
  Let V be a vertex operator algebra. We prove that if U and W are C_1-cofinite
{\mathbb N}-gradable V-modules, then a fusion product U\boxtimes W is
well-defined and also a C_1-cofinite {\mathbb N}-gradable V-module, where the
fusion product is defined by (logarithmic) intertwining operators. This is also
true for C_2-cofinite {\mathbb N}-gradable modules.


title:
Route guidance strategies revisited: Comparison and evaluation in an
  asymmetric two-route traffic system

abstract:
  To alleviate traffic congestion, a variety of route guidance strategies has
been proposed for intelligent transportation systems. A number of the
strategies are proposed and investigated on a symmetric two-route traffic
system over the past decade. To evaluate the strategies in a more general
scenario, this paper conducts eight prevalent strategies on a asymmetric
two-route traffic network with different slowdown behaviors on alternative
routes. The results show that only mean velocity feedback strategy is able to
equalize travel time, i.e., approximate user optimality; while the others fail
due to incapability of establishing relations between the feedback parameters
and travel time. The paper helps better understand these strategies, and
suggests mean velocity feedback strategy if the authority intends to achieve
user optimality.


title: Light output simulation of LYSO single crystal

abstract:
  We used the Geant4 simulation toolkit to estimate the light collection in a
LYSO crystal by using cosmic muons and E=105 MeV electrons. The light output as
a function of the crystal length is studied. Significant influence of the
crystal wrapping in the reflective paper and optical grease coupling to the
photodetectors on the light output is demonstrated.


title:
Real Time Bid Optimization with Smooth Budget Delivery in Online
  Advertising

abstract:
  Today, billions of display ad impressions are purchased on a daily basis
through a public auction hosted by real time bidding (RTB) exchanges. A
decision has to be made for advertisers to submit a bid for each selected RTB
ad request in milliseconds. Restricted by the budget, the goal is to buy a set
of ad impressions to reach as many targeted users as possible. A desired action
(conversion), advertiser specific, includes purchasing a product, filling out a
form, signing up for emails, etc. In addition, advertisers typically prefer to
spend their budget smoothly over the time in order to reach a wider range of
audience accessible throughout a day and have a sustainable impact. However,
since the conversions occur rarely and the occurrence feedback is normally
delayed, it is very challenging to achieve both budget and performance goals at
the same time. In this paper, we present an online approach to the smooth
budget delivery while optimizing for the conversion performance. Our algorithm
tries to select high quality impressions and adjust the bid price based on the
prior performance distribution in an adaptive manner by distributing the budget
optimally across time. Our experimental results from real advertising campaigns
demonstrate the effectiveness of our proposed approach.


title: Universal deformation rings and fusion

abstract:
  Let p be a prime, M be a finite group, F be the field with p elements, and V
be an absolutely irreducible FM-module. Then V has a universal deformation ring
R(M,V) whose structure is closely related to the first and second cohomology
groups of M with coefficients in Hom_F(V,V). We consider the case when M is an
extension of a dihedral group G whose order is relatively prime to p by an
elementary abelian p-group N of rank 2. We determine the cohomology groups and
also R(M,V) for various V and show to what extent R(M,V) sees the fusion of N
in M.


title: Novel variational model for inpainting in the wavelet domain

abstract:
  Wavelet domain inpainting refers to the process of recovering the missing
coefficients during the image compression or transmission stage. Recently, an
efficient algorithm framework which is called Bregmanized operator splitting
(BOS) was proposed for solving the classical variational model of wavelet
inpainting. However, it is still time-consuming to some extent due to the inner
iteration. In this paper, a novel variational model is established to formulate
this reconstruction problem from the view of image decomposition. Then an
efficient iterative algorithm based on the split-Bregman method is adopted to
calculate an optimal solution, and it is also proved to be convergent. Compared
with the BOS algorithm the proposed algorithm avoids the inner iteration and
hence is more simple. Numerical experiments demonstrate that the proposed
method is very efficient and outperforms the current state-of-the-art methods,
especially in the computational time.


title: Scalable Audience Reach Estimation in Real-time Online Advertising

abstract:
  Online advertising has been introduced as one of the most efficient methods
of advertising throughout the recent years. Yet, advertisers are concerned
about the efficiency of their online advertising campaigns and consequently,
would like to restrict their ad impressions to certain websites and/or certain
groups of audience. These restrictions, known as targeting criteria, limit the
reachability for better performance. This trade-off between reachability and
performance illustrates a need for a forecasting system that can quickly
predict/estimate (with good accuracy) this trade-off. Designing such a system
is challenging due to (a) the huge amount of data to process, and, (b) the need
for fast and accurate estimates. In this paper, we propose a distributed fault
tolerant system that can generate such estimates fast with good accuracy. The
main idea is to keep a small representative sample in memory across multiple
machines and formulate the forecasting problem as queries against the sample.
The key challenge is to find the best strata across the past data, perform
multivariate stratified sampling while ensuring fuzzy fall-back to cover the
small minorities. Our results show a significant improvement over the uniform
and simple stratified sampling strategies which are currently widely used in
the industry.


title:
Isolation, equidistribution, and orbit closures for the SL(2,R) action
  on Moduli space

abstract:
  We prove results about orbit closures and equidistribution for the SL(2,R)
action on the moduli space of compact Riemann surfaces, which are analogous to
the theory of unipotent flows. The proofs of the main theorems rely on the
measure classification theorem of [EMi2] and a certain isolation property of
closed SL(2,R) invariant manifolds developed in this paper.


title: Long-range FMR driven spin pumping through a nonmagnetic insulator

abstract:
  Ferromagnetic resonance (FMR) driven spin pumping is an emerging technique
for injection of a pure spin current from a ferromagnet (FM) into a
non-magnetic (NM) material without an accompanying charge current. It is widely
believed that this pumping proceeds exclusively via a short-range exchange
interaction at the FM/NM interface. Here we report robust, long-range spin
pumping from the ferrimagnetic double perovskite Sr2FeMoO6 (SFMO) into Pt
across an insulating barrier up to 200 nm thick, and systematically rule out
all known spurious effects. This result demonstrates dynamic spin injection
over a distance far beyond the coupling range of the exchange interaction,
exposing the need to consider other coupling mechanisms. The characteristic
length scale for magnetic textures in Sr2FeMoO6 is approximately 150 nm,
resulting from structural antiphase boundaries, thus raising the possibility
that magnetic dipole coupling underlies the observed long range spin transfer.
This discovery reveals a route to dynamic angular momentum transfer between a
FM and a NM in the absence of mediation by itinerant electrons and promises new
spin-functional devices employing long-range spin pumping.


title: Optical Spectra of Flat-Spectrum ICRF Radio Sources

abstract:
  Continuing our program of spectroscopic observations of ICRF sources, we
present redshifts for 120 quasars and radio galaxies. Data were obtained with
five telescopes: the 3.58m ESO New Technology Telescope (NTT), the two 8.2m
Gemini telescopes, the 2.5m Nordic Optical Telescope (NOT), and the 6.0m Big
Azimuthal Telescope (BTA) of the Special Astrophysical Observatory in Russia.
  The targets were selected from the International VLBI Service for Geodesy &
Astrometry (IVS) candidate International Celestial Reference Catalogue which
forms part of an observational VLBI program to strengthen the celestial
reference frame. We obtained spectra of the potential optical counterparts of
more than 150 compact flat-spectrum radio sources, and measured redshifts of
120 emission-line objects, together with 19 BL Lac objects. These
identifications add significantly to the precise radio--optical frame tie to be
undertaken by Gaia, due to be launched in 2013, and to the existing data
available for analysing source proper motions over the celestial sphere. We
show that the distribution of redshifts for ICRF sources is consistent with the
much larger sample drawn from FIRST and SDSS, implying that the ultra-compact
VLBI sources are not distinguished from the overall radio-loud quasar
population.
  In addition, we obtained NOT spectra for five radio sources from the FIRST
and NVSS catalogs, selected on the basis of their red colors, which yielded
three quasars with z>4.


title:
Large tensile strain induced monoclinic MB phase in BiFeO3 epitaxial
  thin films on PrScO3 substrate

abstract:
  Crystal and domain structures of tensile-strained BiFeO3 films grown on
orthorhombic (110)o PrScO3 substrates were investigated. All films possess a
MB-type monoclinic structure with 109o stripe domains oriented along the
[\=i10]o direction. For films thicknesses less than ~40 nm, presence of
well-ordered domains is proved by the detection of satellite peaks in
synchrotron x-ray diffraction studies. For thicker films, For thicker films,
only the Bragg reflections from tilted domains were detected. This is
attributed to the broader domain size distribution in thicker films.Using
planar electrodes,the in-plane polarization of the MB phase is determined to be
85 uC/cm2, which is much larger than that of compressive strained BiFeO3 films.
Our results further reveal that the substrate monoclinic distortion plays a
major role in determining the stripe domain formation of the rhombohedral
ferroic epitaxial thin films, which sheds light to the understanding of elastic
domain structure evolution in many other functional oxide thin films as well.


title: Small complete caps from nodal cubics

abstract:
  Bicovering arcs in Galois affine planes of odd order are a powerful tool for
constructing complete caps in spaces of higher dimensions. In this paper we
investigate whether some arcs contained in nodal cubic curves are bicovering.
For $m_1$, $m_2$ coprime divisors of $q-1$, bicovering arcs in $AG(2,q)$ of
size $k\le (q-1)\frac{m_1+m_2}{m_1m_2}$ are obtained, provided that
$(m_1m_2,6)=1$ and $m_1m_2<\sqrt[4]{q}/3.5$. Such arcs produce complete caps of
size $kq^{(N-2)/2}$ in affine spaces of dimension $N\equiv 0 \pmod 4$. For
infinitely many $q$'s these caps are the smallest known complete caps in
$AG(N,q)$, $N \equiv 0 \pmod 4$.


title:
Turbulence in the SuperModel: Mass Reconstruction with Nonthermal
  Pressure for Abell 1835

abstract:
  The total mass derived from X-ray emission is biased low in a large number of
clusters when compared with the mass estimated via strong and weak lensing.
Suzaku and Chandra observations out to the virial radius report in several
relaxed clusters steep temperature gradients that on assuming pure thermal
hydrostatic equilibrium imply an unphysically decreasing mass profile.
Moreover, the gas mass fraction appears to be inconsistent with the cosmic
value measured from the CMB. Such findings can be interpreted as an evidence
for an additional nonthermal pressure in the outskirts of these clusters. This
nonthermal component may be due to turbulence stirred by residual bulk motions
of extragalactic gas infalling into the cluster. Here we present a SuperModel
analysis of Abell 1835 observed by Chandra out to the virial radius. The
SuperModel formalism can include in the equilibrium a nonthermal component
whose level and distribution are derived imposing that the gas mass fraction
f_{gas} equals the cosmic value at the virial radius. Including such a
nonthermal component, we reconstruct from X rays an increasing mass profile
consistent with the hydrostatic equilibrium also in the cluster outskirts and
in agreement at the virial boundary with the weak lensing value. The increasing
f_{gas} profile confirms that the baryons are not missing but located at the
cluster outskirts.


title: Wave Atom Based Watermarking

abstract:
  Watermarking helps in ensuring originality, ownership and copyrights of a
digital image. This paper aims at embedding a Watermark in an image using Wave
Atom Transform. Preference of Wave Atoms on other transformations has been due
to its sparser expansion, adaptability to the direction of local pattern, and
sharp frequency localization. In this scheme, we had tried to spread the
watermark in an image so that the information at one place is very small and
undetectable. In order to extract the watermark and verify ownership of an
image, one would have the advantage of prior knowledge of embedded locations. A
noise of high amplitude will be needed to be added to the image for watermark
distortion. Furthermore, the information spread will ensure the robustness of
the watermark data. The proposed scheme has the ability to withstand malicious
operations and attacks.


title: A Wave-centric View of Special Relativity

abstract:
  An approach to special relativity is outlined which emphasizes the wave and
field mechanisms which physically produce the relativistic effects, with the
goal of making them seem more natural to students by connecting more explicitly
with prior studies of waves and oscillators.


title:
Probing the Shallow Convection Zone: Rising Motion of Subsurface
  Magnetic Fields in the Solar Active Region

abstract:
  In this Letter we present a seismological detection of a rising motion of
magnetic flux in the shallow convection zone of the Sun, and show estimates of
the emerging speed and its decelerating nature. In order to evaluate the speed
of subsurface flux that creates an active region, we apply six Fourier filters
to the Doppler data of NOAA AR 10488, observed with SOHO/MDI, to detect the
reduction of acoustic power at six different depths from -15 to -2 Mm. All the
filtered acoustic powers show reductions, up to 2 hours before the magnetic
flux first appears at the visible surface. The start times of these reductions
show a rising trend with a gradual deceleration. The obtained velocity is first
several km s^-1 in a depth range of 15--10 Mm, then ~1.5 km s^-1 at 10-5 Mm,
finally ~0.5 km s^-1 at 5-2 Mm. If we assume that the power reduction is
actually caused by the magnetic field, the velocity of order of 1 km s^-1 is
well in accordance with previous observations and numerical studies. Moreover,
the gradual deceleration strongly supports the theoretical model that the
emerging flux slows down in the uppermost convection zone before it expands
into the atmosphere to build an active region.


title: On commutativity of ideal extensions

abstract:
  In this paper we examine the commutativity of ideal extensions. We introduce
methods of constructing such extensions, in particular we construct a
noncommutative ring T which contains a central and idempotent ideal I such that
T/I is a field. This answers a question from [2]. Moreover we classify fields
of characteristic 0 which can be obtained as T/I for some T.


title:
Quasiclassical Treatment and Odd-parity/Triplet Correspondence in
  Topological Superconductors

abstract:
  We construct a quasiclassical framework for topological superconductors with
the strong spin-orbit coupling such as CuxBi2Se3. In the manner of the
quasiclassical treatment, decomposing the slowly varying component from the
total quasi-particle wave function, the original massive Dirac Bogoliubov-de
Gennes (BdG) Hamiltonian derived from the tight-binding model represented by 8
x 8 matrix is reduced to 4 x 4 one. The resultant equations are equivalent to
Andreev-type equations of singlet or triplet superconductors, in which the
apparent spin-orbit coupling vanishes. Using this formalism, we find a fact
that the odd-parity superconductivity in topological superconductors turns to
the spin-triplet one. % without the spin-orbit coupling through the
quasiclassical treatment. Moreover, in terms of the quasiclassical treatment,
we show that the topologically-protected zero-energy states in topological
superconductors has the correspondence to the Andreev bound states established
in a long history of studies for the unconventional superconductors. This
clearly indicates that low-energy non-trivial superconducting properties in the
topological superconductors can be analyzed by the established theoretical
descriptions on the spin-triplet superconductors.


title: Lasers for coherent optical satellite links with large dynamics

abstract:
  We present the experimental realization of a laser system for ground to
satellite optical Doppler ranging at the atmospheric turbulence limit. Such a
system needs to display good frequency stability (a few parts in 10^{-14})
whilst allowing large and well controlled frequency sweeps of +/- 12 GHz at
rates exceeding 100 MHz/s. Furthermore it needs to be sufficiently compact and
robust for transportation to different astronomical observation sites where it
is to be interfaced with satellite ranging telescopes. We demonstrate that our
system fulfills those requirements and should therefore allow operation of
ground to low Earth orbit satellite coherent optical links limited only by
atmospheric turbulence.


title:
Probe the 2$s_{1/2}$ and 1$d_{3/2}$ state level inversion with
  electron-nucleus scattering

abstract:
  The neutron-rich even-even nuclei $^{26-40}$Mg, $^{28-46}$Si, $^{30-48}$S,
and $^{32-56}$Ar are calculated with the RMF model and the phase-shift electron
scattering method. Results show that level inversion of the 2$s_{1/2}$ and
1$d_{3/2}$ proton states may occur for the magnesium, silicon, sulphur, and
argon isotopes with more neutrons away from the stability line. Calculations
show that the variation of the central charge densities for $^{30-48}$S, and
$^{32-56}$Ar are very sensitive to the 2$s_{1/2}$ and 1$d_{3/2}$ proton state
level inversion, and the level inversion can lead to a large measurable central
charge depletion to the charge density distributions for the neutron-rich
isotopes. Calculations also show that the charge density differences between
the isotopes with and without central charge depletion can reveal not only the
level inversion of the 2$s_{1/2}$ and 1$d_{3/2}$ proton states but also the
behavior of the proton wave functions of both states. The results can provide
references for the possible study of the nuclear level inversion and nuclear
bubble phenomenon with electron scattering off short-lived nuclei at RIKEN
or/and GSI in the future. In addition, direct nuclear reaction $^{44}$S(n,
d)$^{43}$P or $^{44}$S($^{3}$H, $\alpha$)$^{43}$P might also be a possible way
to study the 2$s_{1/2}$ and 1$d_{3/2}$ proton state level inversion.


title:
Determination of S-curves with applications to the theory of
  nonhermitian orthogonal polynomials

abstract:
  This paper deals with the determination of the S-curves in the theory of
non-hermitian orthogonal polynomials with respect to exponential weights along
suitable paths in the complex plane. It is known that the corresponding complex
equilibrium potential can be written as a combination of Abelian integrals on a
suitable Riemann surface whose branch points can be taken as the main
parameters of the problem. Equations for these branch points can be written in
terms of periods of Abelian differentials and are known in several equivalent
forms. We select one of these forms and use a combination of analytic an
numerical methods to investigate the phase structure of asymptotic zero
densities of orthogonal polynomials and of asymptotic eigenvalue densities of
random matrix models. As an application we give a complete description of the
phases and critical processes of the standard cubic model.


title: Homotopy coherent centers versus centers of homotopy categories

abstract:
  Centers of categories capture the natural operations on their objects.
Homotopy coherent centers are introduced here as an extension of this notion to
categories with an associated homotopy theory. These centers can also be
interpreted as Hochschild cohomology type invariants in contexts that are not
necessarily linear or stable, and we argue that they are more appropriate to
higher categorical contexts than the centers of their homotopy or derived
categories. Among many other things, we present an obstruction theory for
realizing elements in the centers of homotopy categories, and a Bousfield-Kan
type spectral sequence that computes the homotopy groups. Nontrivial classes of
examples are given as illustration throughout.


title: Vertex models, TASEP and Grothendieck polynomials

abstract:
  We examine the wavefunctions and their scalar products of a one-parameter
family of integrable five vertex models. At a special point of the parameter,
the model investigated is related to an irreversible interacting stochastic
particle system the so-called totally asymmetric simple exclusion process
(TASEP). By combining the quantum inverse scattering method with a matrix
product representation of the wavefunctions, the on/off-shell wavefunctions of
the five vertex models are represented as a certain determinant form. Up to
some normalization factors, we find the wavefunctions are given by Grothendieck
polynomials, which are a one-parameter deformation of Schur polynomials.
Introducing a dual version of the Grothendieck polynomials, and utilizing the
determinant representation for the scalar products of the wavefunctions, we
derive a generalized Cauchy identity satisfied by the Grothendieck polynomials
and their duals. Several representation theoretical formulae for Grothendieck
polynomials are also presented. As a byproduct, the relaxation dynamics such as
Green functions for the periodic TASEP are found to be described in terms of
Grothendieck polynomials.

categories: math-ph cond-mat.stat-mech math.MP math.QA nlin.SI


title:
Clustering Algorithms for Scale-free Networks and Applications to Cloud
  Resource Management

abstract:
  In this paper we introduce algorithms for the construction of scale-free
networks and for clustering around the nerve centers, nodes with a high
connectivity in a scale-free networks. We argue that such overlay networks
could support self-organization in a complex system like a cloud computing
infrastructure and allow the implementation of optimal resource management
policies.


title:
Universal Superfluid Transition and Transport Properties of
  Two-Dimensional Dirty Bosons

abstract:
  We study the phase diagram of two-dimensional, interacting bosons in the
presence of a correlated disorder in continuous space, using large-scale finite
temperature quantum Monte Carlo simulations. We show that the superfluid
transition is strongly protected against disorder. It remains of the
Berezinskii-Kosterlitz-Thouless type up to disorder strengths comparable to the
chemical potential. Moreover, we study the transport properties in the strong
disorder regime where a zero-temperature Bose-glass phase is expected. We show
that the conductance exhibits a thermally activated behavior vanishing only at
zero temperature. Our results point towards the existence of Bose bad-metal
phase as a precursor of the Bose-glass phase.


title: Complex dimension of additive subgroups of R^{n}

abstract:
  In this paper, we define the complex dimension of any additive subgroup of
R^{n}$which generalize the euclidien dimension given for the vector space. We
give an explicit method to calculate this dimension.


title: A non-local theory of massive gravity

abstract:
  We construct a fully covariant theory of massive gravity which does not
require the introduction of an external reference metric, and overcomes the
usual problems of massive gravity theories (fatal ghosts instabilities,
acausality and/or vDVZ discontinuity). The equations of motion of the theory
are non-local, but respect causality. The starting point is the quadratic
action proposed in the context of the degravitation idea. We show that it is
possible to extended it to a fully non-linear covariant theory. This theory
describes the five degrees of freedom of a massive graviton plus a scalar
ghost. However, contrary to generic non-linear extensions of Fierz-Pauli
massive gravity, the ghost has the same mass m as the massive graviton,
independently of the background, and smoothly goes into a non-radiative degree
of freedom for m-> 0. As a consequence, for $m\sim H_0$ the vacuum instability
induced by the ghost is irrelevant even over cosmological time-scales. We
finally show that an extension of the model degravitates a vacuum energy
density of order $M_{Planck}^4$ down to a value of order $M_{Planck}^2 m^2$,
which for $m \sim H_0$ is of order of the observed value of the vacuum energy
density.


title: Grounded Lipschitz functions on trees are typically flat

abstract:
  A grounded M-Lipschitz function on a rooted d-ary tree is an integer-valued
map on the vertices that changes by at most along edges and attains the value
zero on the leaves. We study the behavior of such functions, specifically,
their typical value at the root v_0 of the tree. We prove that the probability
that the value of a uniformly chosen random function at v_0 is more than M+t is
doubly-exponentially small in t. We also show a similar bound for continuous
(real-valued) grounded Lipschitz functions.


title:
Radio properties of the magnetar near Sagittarius A* from observations
  with the Australia Telescope Compact Array

abstract:
  We have carried out observations of the newly-discovered magnetar in the
direction of Sagittarius A* using the Australia Telescope Compact Array in four
frequency bands from 4.5 to 20 GHz. Radio pulsations are clearly detected at
all frequencies. We measure the pulsar's dispersion measure to be 1650 +/- 50
pc/cm^3, the highest of any of the known pulsars. Once Faraday rotation has
been taken into account, the pulse profile is more than 80% linearly polarized
at all frequencies and has a small degree (5%) of circular polarization. The
rotation measure of -67000 +/- 500$ rad/m^2 is the largest (in magnitude) ever
measured for a pulsar but still a factor 8 smaller than Sgr A* itself. The
combination of the dispersion and rotation measures implies an integrated
magnetic field strength of -50uG along the line of sight. The flux density
appears to have increased by about a factor of two between observations made 30
days apart. This object therefore joins the small class of radio emitting
magnetars.


title:
Local Existence for the Spatially Homogeneous Boltzmann Equation with
  Soft Potentials

abstract:
  We prove a local-in-time existence and uniqueness theorem for a smooth
classical solution to the spatially homogeneous Boltzmann equation with cutoff
soft potentials. Our proof is based on a series of bilinear estimates for the
integrability and Sobolev regularity of the associated collision operator.
While the global-in-time existence is left inconclusive, we give a lower bound
of the maximal time of existence and a necessary condition for finite time
extinction of existence.


title: Phase-Priority based Directory Coherence for Multicore Processor

abstract:
  As the number of cores in a single chip increases, a typical implementation
of coherence protocol adds significant hardware and complexity overhead.
Besides, the performance of CMP system depends on the data access latency,
which is highly affected by coherence protocol and on-chip interconnect. In
this paper, we propose PPB (Phase-Priority Based) cache coherence protocol, an
optimization of modern directory coherence protocol. We take advantage of the
observation that transient states occur in directory coherence protocol,
resulting in some unnecessary transient states and stalling. PPB cache
coherence protocol decouples a coherence transaction and introduces the idea of
phase message. This phase is considered as the priority of the message.
Additionally, we also add new priority-based arbitrators in on-chip network to
support PPB cache coherence protocol. This mechanism in on-chip network can
support effective cache access, which makes the on-chip network more efficient.
Our analysis on an execution-driven full system simulator using SPLASH-2
benchmark shows that PPB cache coherence outperforms a MESI based directory,
and the number of unnecessary transient states and stalling reduces up to 24%.
Also it reported the speedup of 7.4%. Other advantages of this strategy are
reduced delay of flits and significantly less energy consumption in on-chip
network.


title: Multicanonical MCMC for Sampling Rare Events

abstract:
  Multicanonical MCMC (Multicanonical Markov Chain Monte Carlo; Multicanonical
Monte Carlo) is discussed as a method of rare event sampling. Starting from a
review of the generic framework of importance sampling, multicanonical MCMC is
introduced, followed by applications in random matrices, random graphs, and
chaotic dynamical systems. Replica exchange MCMC (also known as parallel
tempering or Metropolis-coupled MCMC) is also explained as an alternative to
multicanonical MCMC. In the last section, multicanonical MCMC is applied to
data surrogation; a successful implementation in surrogating time series is
shown. In the appendices, calculation of averages and normalizing constant in
an exponential family, phase coexistence, simulated tempering, parallelization,
and multivariate extensions are discussed.

categories: cond-mat.stat-mech cond-mat.dis-nn nlin.CD physics.comp-ph physics.data-an


title: Weighted Approach to General Entropy Function

abstract:
  The definition of weighted entropy allows for easy calculation of the entropy
of the mixture of measures. In this paper we investigate the problem of
equivalent definition of the general entropy function in weighted form. We show
that under reasonable condition, which is satisfied by the well-known Shannon,
R\'enyi and Tsallis entropies, every entropy function can be defined
equivalently in the weighted way. As a corollary, we show how use the weighted
form to compute Tsallis entropy of the mixture of measures.


title: Cancellation-Free Circuits in Unbounded and Bounded Depth

abstract:
  We study the notion of "cancellation-free" circuits. This is a restriction of
linear Boolean circuits (XOR circuits), but can be considered as being
equivalent to previously studied models of computation. The notion was coined
by Boyar and Peralta in a study of heuristics for a particular circuit
minimization problem. They asked how large a gap there can be between the
smallest cancellation-free circuit and the smallest linear circuit. We show
that the difference can be a factor $\Omega(n/\log^{2}n)$. This improves on a
recent result by Sergeev and Gashkov who have studied a similar problem.
Furthermore, our proof holds for circuits of constant depth. We also study the
complexity of computing the Sierpinski matrix using cancellation-free circuits
and give a tight $\Omega(n\log n)$ lower bound.


title:
Patterns of Genuine Multipartite Entanglement in Frustrated Quantum Spin
  Systems

abstract:
  We investigate the behavior of genuine multipartite entanglement of
paradigmatic frustrated quantum spin systems. We consider six different spin
models, whose frustration ranges from being very high to very low. We find that
the highly frustrated quantum spin systems are near-maximally genuine
multipartite entangled, while those with low frustration do not possess a
similar definite behavior with regard to their genuine multipartite
entanglement.


title:
A deterministic model for the occurrence and dynamics of multiple
  mutations in hierarchically organized tissues

abstract:
  We model a general, hierarchically organized tissue by a multi compartment
approach, allowing any number of mutations within a cell. We derive closed
solutions for the deterministic clonal dynamics and the reproductive capacity
of single clones. Our results hold for the average dynamics in a hierarchical
tissue characterized by an arbitrary combination of proliferation parameters.


title: Planck constraints on single-field inflation

abstract:
  We place observational constraints on slow-variation single-field
inflationary models by carrying out the cosmological Monte Carlo simulation
with the recent data of Planck combined with the WMAP large-angle polarization,
baryon acoustic oscillations, and ACT/SPT temperature data. Our analysis covers
a wide variety of models with second-order equations of motion-- including
potential-driven slow-roll inflation, non-minimally coupled models, running
kinetic couplings, Brans-Dicke theories, potential-driven Galileon inflation,
field-derivative couplings to the Einstein tensor, and k-inflation. In the
presence of running kinetic exponential couplings, covariant Galileon terms,
and field-derivative couplings, the tensor-to-scalar ratio of the self-coupling
potential gets smaller relative to that in standard slow-roll inflation, but
the models lie outside the 68 % CL observational contour. We also show that
k-inflation models can be tightly constrained by adding the bounds from the
scalar non-Gaussianities. The small-field inflationary models with asymptotic
flat Einstein-frame potentials in the regime phi >> M_{pl} generally fit the
data very well. These include the models such as Kahler-moduli inflation,
non-minimally coupled Higgs inflation, and inflation in Brans-Dicke theories in
the presence of the potential V(phi)=3M^2 (phi-M_{pl})^2/4 with the Brans-Dicke
parameter omega_{BD}<O(1) (which covers the Starobinsky's model
f(R)=R+R^2/(6M^2) as a special case).


title: On locally graded groups with a word whose values are Engel

abstract:
  Let m, n be positive integers, v a multilinear commutator word and w = v^m.
We prove that if G is a locally graded group in which all w-values are n-Engel,
then the verbal subgroup w(G) is locally nilpotent.


title: Running Consensus for Decentralized Detection

abstract:
  This thesis represents a culmination of work and learning that has taken
place over a period of almost three years (2007 - 2010) at the University of
Salerno, and at the University of Connecticut. It is mostly an unified
mathematical dissertation of the running consensus procedures. In the recent
years, the detection using the paradigm of the running consensus has been
recognized as one of the three possible classes of distributed detection in
which the phases of sensing and communication need not be mutually exclusive,
i.e., sensing and communication occur simultaneously. Considering that the
running consensus paradigm is just an intuitive inference procedure, i.e.
sub-optimal w.r.t. an ideal centralized system scheme which is optimal, the
most important result is that it asymptotically reaches the performance of this
ideal scheme.


title:
Single particle fluctuations and directional correlations in driven hard
  sphere glasses

abstract:
  Via event driven molecular dynamics simulations and experiments, we study the
packing fraction and shear-rate dependence of single particle fluctuations and
dynamic correlations in hard sphere glasses under shear. At packing fractions
above the glass transition, correlations increase as shear rate decreases: the
exponential tail in the distribution of single particle jumps broadens and
dynamic four-point correlations increase. Interestingly, however, upon
decreasing the packing fraction, a broadening of the exponential tail is also
observed, while dynamic heterogeneity is shown to decrease. An explanation for
this behavior is proposed in terms of a competition between shear and thermal
fluctuations. Building upon our previous studies [Chikkadi et al, Europhys.
Lett. (2012)], we further address the issue of anisotropy of the dynamic
correlations.


title:
Quantitatively Accurate Calculations of Conductance and Thermopower of
  Molecular Junctions

abstract:
  Thermopower measurements of molecular junctions have recently gained interest
as a characterization technique that supplements the more traditional
conductance measurements. Here we investigate the electronic conductance and
thermopower of benzenediamine (BDA) and benzenedicarbonitrile (BDCN) connected
to gold electrodes using first-principles calculations. We find excellent
agreement with experiments for both molecules when exchange-correlation effects
are described by the many-body GW approximation. In contrast, results from
standard density functional theory (DFT) deviate from experiments by up to two
orders of magnitude. The failure of DFT is particularly pronounced for the
n-type BDCN junction due to the severe underestimation of the lowest unoccupied
molecular orbital (LUMO). The quality of the DFT results can be improved by
correcting the molecular energy levels for self-interaction errors and image
charge effects. Finally, we show that the conductance and thermopower of the
considered junctions are relatively insensitive to the metal-molecule bonding
geometry. Our results demonstrate that electronic and thermoelectric properties
of molecular junctions can be predicted from first-principles calculations when
exchange-correlation effects are taken properly into account.


title: Universe Acceleration in Brane World Models

abstract:
  We examine the cosmology induced on a brane moving in the background of a
five-dimensional black hole, solution of the string effective action. The
evolution, determined by the Israel junction conditions is found to be
compatible with an accelerating universe with the present day acceleration
coming after a decelerating phase. The possible species of the energy-momentum
tensor, localized on the brane, for these solutions to be valid are discussed.


title:
Magnetic field induced nutation of the exciton-polariton polarization in
  (Cd,Zn)Te crystals

abstract:
  We study the polarization dynamics of exciton-polaritons propagating in
sub-mm thick (Cd,Zn)Te bulk crystals using polarimetric time-of-flight
techniques. The application of a magnetic field in Faraday geometry leads to
synchronous temporal oscillations of all Stokes parameters of an initially
linearly or circularly polarized, spectrally broad optical pulse of 150 fs
duration propagating through the crystal. Strong dispersion for photon energies
close to the exciton resonance leads to stretching of the optical pulse to a
duration of 200$-$300 ps and enhancement of magneto-optical effects such as the
Faraday rotation and the non-reciprocal birefringence. The oscillation
frequency of the exciton-polariton polarization increases with magnetic field
$B$, reaching 10 GHz at $B\sim 5$T. Surprisingly, the relative contributions of
Faraday rotation and non-reciprocal birefringence undergo strong changes with
photon energy, which is attributed to a non-trivial spectral dependence of
Faraday rotation in the vicinity of the exciton resonance. This leads to
polarization nutation of the transmitted optical pulse in the time domain. The
results are well explained by a model that accounts for Faraday rotation and
magneto-spatial dispersion in zinc-blende crystals. We evaluate the exciton
$g$-factor $|g_{\rm exc}|=0.2$ and the magneto-spatial constant $V= 5 \times
10^{-12}$ eVcm$\textup{T}^{-1}$.


title: Using Feedback for Secrecy over Graphs

abstract:
  We study the problem of secure message multicasting over graphs in the
presence of a passive (node) adversary who tries to eavesdrop in the network.
We show that use of feedback, facilitated through the existence of cycles or
undirected edges, enables higher rates than possible in directed acyclic graphs
of the same mincut. We demonstrate this using code constructions for canonical
combination networks (CCNs). We also provide general outer bounds as well as
schemes for node adversaries over CCNs.


title: Nucleation and Growth of Droplets in Vapor-Liquid Transitions

abstract:
  Results for the kinetics of vapor-liquid transitions, following temperature
quenches with different densities, are presented from the molecular dynamics
simulations of a Lennard-Jones system. For critical density, bicontinuous
liquid and vapor domains are observed which grow with time obeying the
prediction of hydrodynamic mechanism. On the other hand, for quenches with
density significantly below the critical one, phase separation progresses via
nucleation and growth of liquid droplets. In the latter case, Brownian
diffusion and collision mechanism for the droplet growth is confirmed. We also
discuss the possibility of inter-droplet interaction leading to a different
amplitude in the growth law. Arguments for faster growth, observed at early
time, are also provided.


title:
A new self-consistent basis generation scheme for polaron and bipolaron
  systems

abstract:
  We have developed a new self-consistent scheme of generating variational
basis based on the exactdiagonalization, which can be applied efficiently to
various types of electron-phonon systems. This scheme is quite general and
brings down the size of the variational space by an order of magnitude or even
more in some cases to reproduce the most precise ground state energies and
correlation functions available in the literature. This method has enormous
potential for application to systems with more electrons or in higher
dimensions, which are still beyond the reach of exact-diagonalization just
because of the sheer size of their variational space needed to get reasonably
convergent results.


title: The Degrees of Freedom of the MIMO Y-channel

abstract:
  The degrees of freedom (DoF) of the MIMO Y-channel, a multi-way communication
network consisting of 3 users and a relay, are characterized for arbitrary
number of antennas. The converse is provided by cut-set bounds and novel
genie-aided bounds. The achievability is shown by a scheme that uses
beamforming to establish network coding on-the-fly at the relay in the uplink,
and zero-forcing pre-coding in the downlink. It is shown that the network has
min{2M_2+2M_3,M_1+M_2+M_3,2N} DoF, where M_j and N represent the number of
antennas at user j and the relay, respectively. Thus, in the extreme case where
M_1+M_2+M_3 dominates the DoF expression and is smaller than N, the network has
the same DoF as the MAC between the 3 users and the relay. In this case, a
decode and forward strategy is optimal. In the other extreme where 2N
dominates, the DoF of the network is twice that of the aforementioned MAC, and
hence network coding is necessary. As a byproduct of this work, it is shown
that channel output feedback from the relay to the users has no impact on the
DoF of this channel.


title:
Secrecy Transmission on Block Fading Channels: Theoretical Limits and
  Performance of Practical Codes

abstract:
  We consider a system where an agent (Alice) aims at transmitting a message to
a second agent (Bob) over a set of parallel channels, while keeping it secret
from a third agent (Eve) by using physical layer security techniques. We assume
that Alice perfectly knows the set of channels with respect to Bob, but she has
only a statistical knowledge of the channels with respect to Eve. We derive
bounds on the achievable outage secrecy rates, by considering coding either
within each channel or across all parallel channels. Transmit power is adapted
to the channel conditions, with a constraint on the average power over the
whole transmission. We also focus on the maximum cumulative outage secrecy rate
that can be achieved. Moreover, in order to assess the performance in a real
life scenario, we consider the use of practical error correcting codes. We
extend the definitions of security gap and equivocation rate, previously
applied to the single additive white Gaussian noise channel, to Rayleigh
distributed parallel channels, on the basis of the error rate targets and the
outage probability. Bounds on these metrics are also derived, taking into
account the statistics of the parallel channels. Numerical results are
provided, that confirm the feasibility of the considered physical layer
security techniques.


title: Surfaces of globally $F$-regular and $F$-split type

abstract:
  We prove that normal projective surfaces of dense globally $F$-split type
(resp. globally $F$-regular type) are of Calabi-Yau type (resp. Fano type).


title:
Vibroacoustics of the piano soundboard: Reduced models, mobility
  synthesis, and acoustical radiation regime

abstract:
  In string musical instruments, the sound is radiated by the soundboard,
subject to the strings excitation. This vibration of this rather complex
structure is described here with models which need only a small number of
parameters. Predictions of the models are compared with results of experiments
that have been presented in Ege et al. [Vibroacoustics of the piano soundboard:
(Non)linearity and modal properties in the low- and mid- frequency ranges,
Journal of Sound and Vibration 332 (5) (2013) 1288-1305]. The apparent modal
density of the soundboard of an upright piano in playing condition, as seen
from various points of the structure, exhibits two well-separated regimes,
below and above a frequency flim that is determined by the wood characteristics
and by the distance between ribs. Above flim, most modes appear to be
localised, presumably due to the irregularity of the spacing and height of the
ribs. The low-frequency regime is predicted by a model which consists of
coupled sub-structures: the two ribbed areas split by the main bridge and, in
most cases, one or two so-called cut-off corners. In order to assess the
dynamical properties of each of the subplates (considered here as homogeneous
plates), we propose a derivation of the (low-frequency) modal density of an
orthotropic homogeneous plate which accounts for the boundary conditions on an
arbitrary geometry. Above flim, the soundboard, as seen from a given excitation
point, is modelled as a set of three structural wave-guides, namely the three
inter-rib spacings surrounding the excitation point. Based on these low- and
high-frequency models, computations of the point-mobility and of the apparent
modal densities seen at several excitation points match published measurements.
The dispersion curve of the wave-guide model displays an acoustical radiation
scheme which differs significantly from that of a thin homogeneous plate. It
appears that piano dimensioning is such that the subsonic regime of acoustical
radiation extends over a much wider frequency range than it would be for a
homogeneous plate with the same low-frequency vibration. One problem in piano
manufacturing is examined in relationship with the possible radiation schemes
induced by the models.


title: Rule-Based Application Development using Webdamlog

abstract:
  We present the WebdamLog system for managing distributed data on the Web in a
peer-to-peer manner. We demonstrate the main features of the system through an
application called Wepic for sharing pictures between attendees of the sigmod
conference. Using Wepic, the attendees will be able to share, download, rate
and annotate pictures in a highly decentralized manner. We show how WebdamLog
handles heterogeneity of the devices and services used to share data in such a
Web setting. We exhibit the simple rules that define the Wepic application and
show how to easily modify the Wepic application.


title:
Spectral matching for abundances of 848 stars of the giant branches of
  the globular cluster {\omega} Centauri

abstract:
  We present the effective temperatures, surface gravities and abundances of
iron, carbon and barium of 848 giant branch stars, of which 557 also have
well-defined nitrogen abundances, of the globular cluster {\omega} Centauri.
This work used photometric sources and lower resolution spectra for this
abundance analysis. Spectral indices were used to estimate the oxygen abundance
of the stars, leading to a determination of whether a particular star was
oxygen-rich or oxygen-poor.
  The 557-star subset was analyzed in the context of evolutionary groups, with
four broad groups identified. These groups suggest that there were at least
four main four periods of star formation in the cluster. The exact order of
these star formation events is not yet understood.
  These results compare well with those found at higher resolution and show the
value of more extensive lower resolution spectral surveys. They also highlight
the need for large samples of stars when working with a complex object like
{\omega} Cen.


title: The quest for self-consistency in hydrogen-bond definitions

abstract:
  In the last decades several hydrogen-bond definitions were proposed by
classical computer simulations. Aiming at validating their self-consistency on
a wide range of conditions, here we present a comparative study of six among
the most common hydrogen-bond definitions for temperatures ranging from 220K to
400K and six classical water models. Our results show that, in the interval of
temperatures investigated, a generally weak agreement among definitions is
present. Moreover, cutoff choice for geometrically based definitions depends on
both temperature and water model. As such, analysis of the same water model at
different temperatures as well as different water models at the same
temperature would require the development of specific cutoff values.
Interestingly, large discrepancies were found between two hydrogen-bond
definitions which were recently introduced to improve on more conventional
methods. Our results anticipate that a more universal way to characterize
hydrogen-bonds in classical molecular systems is needed.


title:
Effect of resonant magnetic perturbations with toroidal mode numbers of
  4 and 6 on ELMs in single null H-mode plasmas in MAST

abstract:
  The application of resonant magnetic perturbations (RMPs) with a toroidal
mode number of n=4 or n=6 to lower single null plasmas in the MAST tokamak
produces up to a factor of 5 increase in Edge Localized Mode (ELM) frequency
and reduction in plasma energy loss associated with type-I ELMs. A threshold
current for ELM mitigation is observed above which the ELM frequency increases
approximately linearly with current in the coils. Despite a large scan of
parameters, complete ELM suppression has not been achieved. The results have
been compared to modelling performed using either the vacuum approximation or
including the plasma response. During the ELM mitigated stage clear lobe
structures are observed in visible-light imaging of the X-point region. The
size of these lobes is correlated with the increase in ELM frequency observed.
The characteristics of the mitigated ELMs are similar to those of the natural
ELMs suggesting that they are type I ELMs which are triggered at a lower
pressure gradient. The application of the RMPs in the n=4 and n=6
configurations before the L-H transition has little effect on the power
required to achieve H-mode while still allowing the first ELM to be mitigated.


title: Numerical Verification of the Ternary Goldbach Conjecture up to 8.875e30

abstract:
  We describe a computation that confirms the ternary Goldbach Conjecture up to
8,875,694,145,621,773,516,800,000,000,000 (>8.875e30).


title:
Exact Partition Function Zeros of the Wako-Saito-Mu\~noz-Eaton Protein
  Model

abstract:
  I compute exact partition function zeros of the Wako-Saito-Mu\~noz-Eaton
model for various secondary structural elements and for two proteins, 1BBL and
1I6C, using both analytic and numerical methods. Two-state and barrierless
downhill folding transitions can be distinguished by a gap in the distribution
of zeros at the positive real axis.


title: Electromagnon in ferrimagnetic eps-Fe2O3 nanograin ceramics

abstract:
  Electromagnons are known from multiferroics as spin waves excited by the
electric component of electromagnetic radiation. We report the discovery of an
excitation in the far-infrared spectra of eps-Fe2O3 which we attribute to an
electromagnon appearing below 110 K, where the ferrimagnetic structure becomes
incommensurately modulated. Inelastic neutron scattering shows that the
electromagnon energy corresponds to that of a magnon from the Brillouin zone
boundary. Dielectric measurements did not reveal any sign of ferroelectricity
in eps-Fe2O3 down to 10 K, despite its acentric crystal structure. This shows
that the activation of an electromagnon requires, in addition to the polar
ferrimagnetic structure, a modulation of the magnetic structure. We demonstrate
that a combination of inelastic neutron scattering with infrared and / or
terahertz spectroscopies allows detecting electromagnons in ceramics, where no
crystal-orientation analysis of THz and infrared spectra is possible.


title:
Multiple light scattering and near-field effects in a fractal tree-like
  ensamble of dielectric nanoparticles

abstract:
  We numerically study light scattering and absorption in self-similar
aggregates of dielectric nanoparticles, as generated by simulated ballistic
deposition upon a surface starting from a single seed particle. The resulting
structure exhibits a complex tree-like shape, intended to mimic the morphologic
properties of building blocks of real nanostructured thin films produced by
means of fine controlled physical deposition processes employed in
nanotechnology. The relationship of scattering and absorption cross sections to
morphology is investigated within a computational scheme which thoroughly takes
into account both multiple scattering and near-field effects. Numerical results
are compared with a pre-existing single scattering limited analytical treatment
of light scattering in fractal aggregates of small dielectric particles.


title: Noncommutative Geometry in the LHC-Era

abstract:
  Noncommutative geometry allows to unify the basic building blocks of particle
physics, Yang-Mills-Higgs theory and General relativity, into a single
geometrical framework. The resulting effective theory constrains the couplings
of the particle model and reduces the number of degrees of freedom. After
briefly introducing the basic ideas of noncommutative geometry, I will present
its predictions for the Standard Model and the few known models beyond the
Standard Model. Most of these models, including the Standard Model, are now
ruled out by LHC data. But interesting extensions of the Standard Model which
agree with the presumed Standard Model Scalar mass and predict new particles
are still very much alive and await further experimental data.


title: Pair Production in Non-Perturbative QCD

abstract:
  In this note, we present a method to calculate the vacuum to vacuum
transition amplitude in the presence of the non-abelian background field. The
number of non-perturbative quark-antiquark produced per unit time, per unit
volume and per unit transverse momentum from a given constant chromo-electric
field is calculated and compared with the results found in the literature.


title:
Estimating the quadratic covariation of an asynchronously observed
  semimartingale with jumps

abstract:
  We consider estimation of the quadratic (co)variation of a semimartingale
from discrete observations which are irregularly spaced under high-frequency
asymptotics. In the univariate setting, results by Jacod (2008) are generalized
to the case of irregular observations. In the two-dimensional setup under
non-synchronous observations, we derive a stable central limit theorem for the
Hayashi-Yoshida estimator in the presence of jumps. We reveal how idiosyncratic
and simultaneous jumps affect the asymptotic distribution. Observation times
generated by Poisson processes are explicitly discussed.


title: Quantum parameter estimation affected by unitary disturbance

abstract:
  We provide a general framework for handling the effects of a unitary
disturbance on the estimation of the amplitude $\lambda$ associated to a
unitary dynamics. By computing an analytical and general expression for the
quantum Fisher information, we prove that the optimal estimation precision for
$\lambda$ cannot be outperformed through the addition of such a unitary
disturbance. However, if the dynamics of the system is already affected by an
external field, increasing its strength does not necessary imply a loss in the
optimal estimation precision.


title: Generalized Rose Surfaces and their Visualizations

abstract:
  In this paper we construct a new class of algebraic surfaces in
three-dimensional Euclidean space generated by a cyclic-harmonic curve and a
congruence of circles. We study their properties and visualize them with the
program Mathematica.


title:
Asymptotics of $L_p$-norms of Hermite polynomials and R\'enyi entropy of
  Rydberg oscillator states

abstract:
  The asymptotics of the weighted $L_{p}$-norms of Hermite polynomials, which
describes the R\'enyi entropy of order $p$ of the associated quantum oscillator
probability density, is determined for $n\to\infty$ and $p>0$. Then, it is
applied to the calculation of the R\'enyi entropy of the quantum-mechanical
probability density of the highly-excited (Rydberg) states of the isotropic
oscillator.


title: Single-photon time-dependent spectra in coupled cavity arrays

abstract:
  We show how the input-output formalism for cascaded quantum systems combined
with the quantum trajectory approach yields a compact and physically intuitive
description of single photons propagating through a coupled cavity array. As a
new application we obtain the time-dependent spectrum of such a single photon,
which directly reflects the fact that only certain frequency components of
single-photon wavepackets are trapped inside the cavities and hence are delayed
in time. We include in our description the actual generation of the single
photon, by assuming we have a single emitter in one of the resonators.


title: Lines generate the Picard groups of certain Fermat surfaces

abstract:
  We answer a question of T.Shioda and show that, for any positive integer $m$
prime to 6, the Picard group of the Fermat surface $\Phi_m$ is generated by the
classes of lines contained in $\Phi_m$.


title:
On the fractional Poisson process and the discretized stable
  subordinator

abstract:
  The fractional Poisson process and the Wright process (as discretization of
the stable subordinator) along with their diffusion limits play eminent roles
in theory and simulation of fractional diffusion processes. Here we have
analyzed these two processes, concretely the corresponding counting number and
Erlang processes, the latter being the processes inverse to the former.
Furthermore we have obtained the diffusion limits of all these processes by
well-scaled refinement of waiting times and jumps


title: Fluctuation analysis: can estimates be trusted?

abstract:
  The estimation of mutation probabilities and relative fitnesses in
fluctuation analysis is based on the unrealistic hypothesis that the
single-cell times to division are exponentially distributed. Using the
classical Luria-Delbr\"{u}ck distribution outside its modelling hypotheses
induces an important bias on the estimation of the relative fitness. The model
is extended here to any division time distribution. Mutant counts follow a
generalization of the Luria-Delbr\"{u}ck distribution, which depends on the
mean number of mutations, the relative fitness of normal cells compared to
mutants, and the division time distribution of mutant cells. Empirical
probability generating function techniques yield precise estimates both of the
mean number of mutations and the relative fitness of normal cells compared to
mutants. In the case where no information is available on the division time
distribution, it is shown that the estimation procedure using constant division
times yields more reliable results. Numerical results both on observed and
simulated data are reported.


title:
Solutions to the complex Korteweg-de Vries equation: Blow-up solutions
  and non-singular solutions

abstract:
  In the paper two kinds of solutions are derived for the complex Korteweg-de
Vries equation, including blow-up solutions and non-singular solutions. We
derive blow-up solutions from known 1-soliton solution and a double-pole
solution. There is a complex Miura transformation between the complex
Korteweg-de Vries equation and a modified Korteweg-de Vries equation. Using the
transformation, solitons, breathers and rational solutions to the complex
Korteweg-de Vries equation are obtained from those of the modified Korteweg-de
Vries equation. Dynamics of the obtained solutions are illustrated.


title: Non-thermal quantum phase transitions

abstract:
  We report a kind of quantum phase transition which takes place in isolated
quantum systems with non-thermal equilibrium states and an extra symmetry that
commutes with the Hamiltonian for any values of the system parameters. A
critical energy separates two different phases, one in which the symmetry is
broken. This critical behavior is ruled out as soon as the system is put in
contact with a thermal bath. The critical point is crossed when a sufficent
amount of work is performed on the system, keeping it isolated from the
environment. Different phases are identified by means of an order parameter,
which is only different from zero in the symmetry-breaking phase. The behavior
of the system near the critical point is determined by a set of critical
exponents. We illustrate this phenomenon by means of numerical calculations in
three different two-level systems.


title:
On bifurcation for semilinear elliptic Dirichlet problems on geodesic
  balls

abstract:
  We study bifurcation from a branch of trivial solutions of semilinear
elliptic Dirichlet boundary value problems on a geodesic ball, whose radius is
used as the bifurcation parameter. In the proof of our main theorem we obtain
in addition a special case of an index theorem due to S. Smale.


title: Counting sets with small sumset and applications

abstract:
  We study the number of $k$-element sets $A \subset \{1,\ldots,N\}$ with $|A +
A| \leq K|A|$ for some (fixed) $K > 0$. Improving results of the first author
and of Alon, Balogh, Samotij and the second author, we determine this number up
to a factor of $2^{o(k)} N^{o(1)}$ for most $N$ and $k$. As a consequence of
this and a further new result concerning the number of sets $A \subset
\mathbf{Z}/N\mathbf{Z}$ with $|A +A| \leq c |A|^2$, we deduce that the random
Cayley graph on $\mathbf{Z}/N\mathbf{Z}$ with edge density~$\frac{1}{2}$ has no
clique or independent set of size greater than $\big( 2 + o(1) \big) \log_2 N$,
asymptotically the same as for the Erd\H{o}s-R\'enyi random graph. This
improves a result of the first author from 2003 in which a bound of $160 \log_2
N$ was obtained. As a second application, we show that if the elements of $A
\subset \mathbf{N}$ are chosen at random, each with probability $1/2$, then the
probability that $A+A$ misses exactly $k$ elements of $\mathbf{N}$ is equal to
$\big( 2 + o(1) \big)^{-k/2}$ as $k \to \infty$.


title: Informative Bayesian inference for the skew-normal distribution

abstract:
  Motivated by the analysis of the distribution of university grades, which is
usually asymmetric, we discuss two informative priors for the shape parameter
of the skew-normal distribution, showing that they lead to closed-form
full-conditional posterior distributions, particularly useful in MCMC
computation. Gibbs sampling algorithms are discussed for the joint vector of
parameters, given independent prior distributions for the location and scale
parameters. Simulation studies are performed to assess the performance of Gibbs
samplers and to compare the choice of informative priors against a
non-informative one. The method is used to analyze the grades of the basic
statistics examination of the first-year undergraduate students at the School
of Economics, University of Padua, Italy.


title:
Spatial correlations in nonequilibrium reaction-diffusion problems by
  the Gillespie algorithm

abstract:
  We present a study of the spatial correlation functions of a one-dimensional
reaction-diffusion system in both equilibrium and out of equilibrium. For the
numerical simulations we have employed the Gillespie algorithm dividing the
system in cells to treat diffusion as a chemical process between adjacent
cells. We find that the spatial correlations are spatially short ranged in
equilibrium but become long ranged in nonequilibrium. These results are in good
agreement with theoretical predictions from fluctuating hydrodynamics for a
one-dimensional system and periodic boundary conditions.

categories: cond-mat.stat-mech cond-mat.mes-hall physics.bio-ph physics.chem-ph


title: Mining Frequent Neighborhood Patterns in Large Labeled Graphs

abstract:
  Over the years, frequent subgraphs have been an important sort of targeted
patterns in the pattern mining literatures, where most works deal with
databases holding a number of graph transactions, e.g., chemical structures of
compounds. These methods rely heavily on the downward-closure property (DCP) of
the support measure to ensure an efficient pruning of the candidate patterns.
When switching to the emerging scenario of single-graph databases such as
Google Knowledge Graph and Facebook social graph, the traditional support
measure turns out to be trivial (either 0 or 1). However, to the best of our
knowledge, all attempts to redefine a single-graph support resulted in measures
that either lose DCP, or are no longer semantically intuitive.
  This paper targets mining patterns in the single-graph setting. We resolve
the "DCP-intuitiveness" dilemma by shifting the mining target from frequent
subgraphs to frequent neighborhoods. A neighborhood is a specific topological
pattern where a vertex is embedded, and the pattern is frequent if it is shared
by a large portion (above a given threshold) of vertices. We show that the new
patterns not only maintain DCP, but also have equally significant semantics as
subgraph patterns. Experiments on real-life datasets display the feasibility of
our algorithms on relatively large graphs, as well as the capability of mining
interesting knowledge that is not discovered in prior works.


title: Anomalous second order coherence and $g^{(2)}$ complementarity

abstract:
  This paper is a summary of my talk at SPIE2013. The organizers were kind
enough to invite me to talk about anything I wanted, and I chose to bring up
the notion of higher order complementarity and the fact that it may not be
monotonic. I enter this discussion, which is rather speculative at this stage,
by calculating a specific example. This is to be regarded as work in progress.
  We analyze a two-particle state and show that when mismatching the detector
frequency response and the field frequency spectrum, several anomalous features
become apparent. In particular, while we find several well known features, such
as $g^{(2)}(\tau=0)=1/2$ for completely indistinguishable particles, we also
find that as the photons are slightly separated and may be distinguished,
$g^{(2)}$ may oscillate as a function of the detector bandwidth. Beyond the
latter interesting observation for which we cannot find a simple physical
origin, we also suggest, an interpretation with regard to an oscillating
$g^{(2)}$ complementarity.


title: b and c spectrocopy at LHCb

abstract:
  We will present recent results in the field of b and c spectroscopy at LHCb,
with particular attention to the latest studies on the X(3872) quantum numbers
and the Bc new decay modes and mass measurement.


title:
Einstein-Cartan gravitational collapse of a homogeneous Weyssenhoff
  fluid

abstract:
  We consider the gravitational collapse of a spherically symmetric homogeneous
matter distribution consisting of a Weyssenhoff fluid in the presence of a
negative cosmological constant. Our aim is to investigate the effects of
torsion and spin averaged terms on the final outcome of the collapse. For a
specific interior spacetime setup, namely the homogeneous and isotropic FLRW
metric, we obtain two classes of solutions to the field equations where
depending on the relation between spin source parameters, $(i)$ the collapse
procedure culminates in a spacetime singularity or $(ii)$ it is replaced by a
non-singular bounce. We show that, under certain conditions, for a specific
subset of the former solutions, the formation of trapped surfaces is prevented
and thus the resulted singularity could be naked. The curvature singularity
that forms could be gravitationally strong in the sense of Tipler. Our
numerical analysis for the latter solutions shows that the collapsing dynamical
process experiences four phases, so that two of which occur at the pre-bounce
and the other two at post-bounce regimes. We further observe that there can be
found a minimum radius for the apparent horizon curve, such that the main
outcome of which is that there exists an upper bound for the size of the
collapsing body, below which no horizon forms throughout the whole scenario.


title:
Dynamics and Growth of Droplets Close to the Two-Phase Coexistence Curve
  in Fluids

abstract:
  Results from the state-of-the-art molecular dynamics simulations are
presented for both equilibrium and nonequilibrium dynamics following
vapor-liquid transition in a single component Lennard-Jones system. We have
fixed the overall density close to the vapor-branch of the coexistence curve so
that the liquid phase forms droplet structure in the background of vapor phase.
In the equilibrium case, the motion of a single droplet is studied in both
microcanonical and canonical ensembles, in the latter case a hydrodynamics
preserving Nos\'{e}-Hoover thermostat was used to control the temperature. The
droplet nucleation, motion, collision and coalescence dynamics in the
nonequilibrium case were studied in the canonical ensemble with Nos\'{e}-Hoover
thermostat. There it was observed that the average droplet volume grows
linearly with time. Between two successive collisions, the size of the droplets
remain same even though all the constituent particles do not move with the
droplets \textminus some leave, others join. It is seen that the number of
original particles in a droplet decays exponentially fast. Results from a
liquid-liquid transition are also presented in the equilibrium context.
Dynamics of droplets in equilibrium appears to be at variant with the
nonequilibrium case.


title: Numerical Computations Concerning the GRH

abstract:
  We describe two new algorithms for the efficient and rigorous computation of
Dirichlet L-functions and their use to verify the Generalised Riemann
Hypothesis for all such L-functions associated with primitive characters of
modulus q<=400,000. For even q, we check to height t_0=max(1e8/q,7.5e7/q+200)
and for odd q to height t_0=max(1e8/q,3.75e7/q+200).


title:
Twists, realizations and Hopf algebroid structure of kappa-deformed
  phase space

abstract:
  The quantum phase space described by Heisenberg algebra possesses undeformed
Hopf algebroid structure. The $\kappa$-deformed phase space with noncommutative
coordinates is realized in terms of undeformed quantum phase space. There are
infinitely many such realizations related by similarity transformations. For a
given realization we construct corresponding coproducts of commutative
coordinates and momenta (bialgebroid structure). The $\kappa$-deformed phase
space has twisted Hopf algebroid structure. General method for the construction
of twist operator (satisfying cocycle and normalization condition)
corresponding to deformed coalgebra structure is presented. Specially, twist
for natural realization (classical basis) of $\kappa$-Minkowski spacetime is
presented. The cocycle condition, $\kappa$-Poincar\'{e} algebra and $R$-matrix
are discussed. Twist operators in arbitrary realizations are constructed from
the twist in the given realization using similarity transformations. Some
examples are presented. The important physical applications of twists,
realizations, $R$-matrix and Hopf algebroid structure are discussed.


title:
Characterizing Exoplanets in the Visible and Infrared: A Spectrometer
  Concept for the EChO Space Mission

abstract:
  Transit-spectroscopy of exoplanets is one of the key observational techniques
to characterize the extrasolar planet and its atmosphere. The observational
challenges of these measurements require dedicated instrumentation and only the
space environment allows an undisturbed access to earth-like atmospheric
features such as water or carbon-dioxide. Therefore, several exoplanet-specific
space missions are currently being studied. One of them is EChO, the Exoplanet
Characterization Observatory, which is part of ESA's Cosmic Vision 2015-2025
program, and which is one of four candidates for the M3 launch slot in 2024. In
this paper we present the results of our assessment study of the EChO
spectrometer, the only science instrument onboard this spacecraft. The
instrument is a multi-channel all-reflective dispersive spectrometer, covering
the wavelength range from 400 nm to 16 microns simultaneously with a moderately
low spectral resolution. We illustrate how the key technical challenge of the
EChO mission - the high photometric stability - influences the choice of
spectrometer concept and drives fundamentally the instrument design. First
performance evaluations underline the fitness of the elaborated design solution
for the needs of the EChO mission.


title: Light-emitting waveguide-plasmon polaritons

abstract:
  We demonstrate the generation of light in an optical waveguide strongly
coupled to a periodic array of metallic nanoantennas. This coupling gives rise
to hybrid waveguide-plasmon polaritons (WPPs), which undergo a transmutation
from plasmon to waveguide mode and viceversa as the eigenfrequency detuning of
the bare states transits through zero. Near zero detuning, the structure is
nearly transparent in the far-field but sustains strong local field
enhancements inside the waveguide. Consequently, light-emitting WPPs are
strongly enhanced at energies and in-plane momenta for which WPPs minimize
light extinction. We elucidate the unusual properties of these polaritons
through a classical model of coupled harmonic oscillators.


title:
A low-level accretion flare during the quiescent state of the
  neutron-star X-ray transient SAX J1750.8-2900

abstract:
  We report on a series of Swift/XRT observations, performed between February
and 22 March 2012, during the quiescent state of the neutron-star X-ray binary
SAX J1750.8-2900. In these observations, the source was either just detected or
undetected, depending on the exposure length (which ranged from ~0.3 to ~3.8
ks). The upper limits for the non-detections were consistent with the detected
luminosities (when fitting a thermal model to the spectrum) of ~1E34 erg/s
(0.5-10 keV). This level is consistent with what has been measured previously
for this source in quiescence. However, on March 17 the source was found to
have an order of magnitude larger count rate. When fitting the flare spectrum
with an absorbed power-law model, we obtained a flare luminosity of (3-4) 1E34
erg/s (0.5-10 keV). Follow-up Swift observations showed that this flare lasted
<16 days. This event was very likely due to a brief episode of low-level
accretion onto the neutron star and provides further evidence that the
quiescent state of neutron-star X-ray transients might not be as quiet as is
generally assumed. The detection of this low-level accretion flare raises the
question whether the quiescent emission of the source (outside the flare) could
also be due to residual accretion, albeit continuous instead of episodic.
However, we provide arguments which would suggest that the lowest intensity
level might instead represent the cooling of the accretion-heated neutron star.


title: Lagrangian Curves in Affine Symplectic 4-space

abstract:
  Lagrangian curves in 4-space entertain intriguing relationships with second
order deformation of plane curves under the special affine group and null
curves in a 3-dimensional Lorentzian space form. We provide a natural affine
symplectic frame for Lagrangian curves. It allows us to classify Lagrangrian
curves with constant symplectic curvatures, to construct a class of Lagrangian
tori and determine Lagrangian geodesics.


title:
Proton (antiproton) elastic scattering at energies from FNAL to LHC in
  the tripole pomeron-odderon model

abstract:
  The model of elastic scattering amplitudes dominated by the triple (at $t=0$)
pomeron pole suggested earlier is modified to confront to existing experimental
data on $pp$ and $\bar pp$ total and differential cross sections at
$\sqrt{s}\geq 19$ GeV and $|t|\leq 14.2$ GeV$^{2}$ including the newest TOTEM
data. Predictions for the future TOTEM measurements at 13 and 14 TeV are given.


title:
A semi-analytical model for the wrinkling of laminates during
  consolidation over a corner radius

abstract:
  If carbon fibre layers are prevented from slipping over one another as they
consolidate onto a non-trivial geometry, they can be particularly susceptible
to wrinkling/buckling instabilities. A one dimensional model for wrinkling
during consolidation over an external radius is presented. Critical conditions
for the appearance of wrinkles provide possible manufacturing and design
strategies to minimise wrinkling. Numerical results for the unstable post
buckling paths show localized buckling behaviour which demonstrates qualitative
agreement with micrographs of wrinkles.


title:
Estimation of frequency modulations on wideband signals; applications to
  audio signal analysis

abstract:
  The problem of joint estimation of power spectrum and modulation from
realizations of frequency modulated stationary wideband signals is considered.
The study is motivated by some specific signal classes from which departures to
stationarity can carry relevant information and has to be estimated. The
estimation procedure is based upon explicit modeling of the signal as a
wideband stationary Gaussian signal, transformed by time-dependent, smooth
frequency modulation. Under such assumptions, an approximate expression for the
second order statistics of the transformed signal's Gabor transform is
obtained, which leads to an approximate maximum likelihood estimation
procedure. The proposed approach is validated on numerical simulations.


title:
Unwinding of a cholesteric liquid crystal and bidirectional surface
  anchoring

abstract:
  We examine the influence of bidirectional anchoring on the unwinding of a
planar cholesteric liquid crystal induced by the application of a magnetic
field. We consider a liquid crystal layer confined between two plates with the
helical axis perpendicular to the substrates. We fixed the director twist on
one boundary and allow for bidirectional anchoring on the other by introducing
a high-order surface potential. By minimizing the total free energy for the
system, we investigate the untwisting of the cholesteric helix as the liquid
crystal attempts to align with the magnetic field. The transitions between
metastable states occur as a series of pitchjumps as the helix expels quarter
or half-turn twists, depending on the relative sizes of the strength of the
surface potential and the bidirectional anchoring. We show that secondary easy
axis directions can play a significant role in the unwinding of the cholesteric
in its transition towards a nematic, especially when the surface anchoring
strength is large.


title: Limit laws and automorphism groups of random nonrigid structures

abstract:
  A systematic study is made, for an arbitrary finite relational language with
at least one symbol of arity at least 2, of classes of nonrigid finite
structures. The well known results that almost all finite structures are rigid
and that the class of finite structures has a zero-one law are, in the present
context, the first layer in a hierarchy of classes of finite structures with
increasingly more complex automorphism groups. Such a hierarchy can be defined
in more than one way. For example, the $k$th level of the hierarchy can consist
of all structures having at least $k$ elements which are moved by some
automorphism. Or we can consider, for any finite group $G$, all finite
structures $\mathcal{M}$ such that $G$ is a subgroup of the group of
autmorphisms of $\mathcal{M}$; in this case the "hierarchy" is a partial order.
In both cases, as well as variants of them, each "level" satisfies a logical
limit law, but not a zero-one law (unless $k = 0$ or $G$ is trivial). Moreover,
the number of (labelled or unlabelled) $n$-element structures in one place of
the hierarchy divided by the number of $n$-element structures in another place
always converges to a rational number or to $\infty$ as $n \to \infty$. All
instances of the respective result are proved by an essentially uniform
argument.


title:
A Study of the Di-Hadron Angular Correlation Function in Event by Event
  Ideal Hydrodynamics

abstract:
  The di-hadron angular correlation function is computed within boost
invariant, ideal hydrodynamics for Au+Au collisions at $\sqrt{s}_{NN}=200$ GeV
using Monte Carlo Glauber fluctuating initial conditions. When $0<p_T< 3$ GeV,
the intensity of the flow components and their phases, $\left\{v_n, \Psi_n
\right \}$ ($n=2,3$), are found to be correlated on an event by event basis to
the initial condition geometrical parameters $\left\{\varepsilon_{2,n},
\Phi_{2,n} \right \}$, respectively. Moreover, the fluctuation of the relative
phase between trigger and associated particles, $\Delta_n =\Psi_n^t -
\Psi_n^a$, is found to affect the di-hadron angular correlation function when
different intervals of transverse momentum are used to define the trigger and
the associated hadrons.


title:
Singular Weyl-Titchmarsh-Kodaira theory for one-dimensional Dirac
  operators

abstract:
  We develop singular Weyl-Titchmarsh-Kodaira theory for one-dimensional Dirac
operators. In particular, we establish existence of a spectral transformation
as well as local Borg-Marchenko and Hochstadt-Liebermann type uniqueness
results. Finally, we give some applications to the case of radial Dirac
operators.


title: Inverse uniqueness results for one-dimensional weighted Dirac operators

abstract:
  Given a one-dimensional weighted Dirac operator we can define a spectral
measure by virtue of singular Weyl-Titchmarsh-Kodaira theory. Using the theory
of de Branges spaces we show that the spectral measure uniquely determines the
Dirac operator up to a gauge transformation. Our result applies in particular
to radial Dirac operators and extends the classical results for Dirac operators
with one regular endpoint. Moreover, our result also improves the currently
known results for canonical (Hamiltonian) systems. If one endpoint is limit
circle case, we also establish corresponding two-spectra results.


title: Goya's artwork imaging with Terahertz waves

abstract:
  In this paper we use a Terahertz (THz) time-domain system to image and
analize the structure of an artwork attributed to Spanish artist Goya painted
in 1771. The Thz images show features that cannot be seen in the optical or
X-ray images that providence evidence of its authenticity, which is validated
by other independent studies. For instance, a feature with a strong resemblance
with one of Goya's known signatures is seen in the THz images that cannot be
detected otherwise. This paper shows the feasibility of using THz imaging in
the field of authentication and characterization of artworks. This may be of
great importance in cases where both the signature and specific features that
are critical for the authentication of an artwork remain hidden to visible,
infrared, or X-ray inspection methods.


title: FPT is Characterized by Useful Obstruction Sets

abstract:
  Many graph problems were first shown to be fixed-parameter tractable using
the results of Robertson and Seymour on graph minors. We show that the
combination of finite, computable, obstruction sets and efficient order tests
is not just one way of obtaining strongly uniform FPT algorithms, but that all
of FPT may be captured in this way. Our new characterization of FPT has a
strong connection to the theory of kernelization, as we prove that problems
with polynomial kernels can be characterized by obstruction sets whose elements
have polynomial size. Consequently we investigate the interplay between the
sizes of problem kernels and the sizes of the elements of such obstruction
sets, obtaining several examples of how results in one area yield new insights
in the other. We show how exponential-size minor-minimal obstructions for
pathwidth k form the crucial ingredient in a novel OR-cross-composition for
k-Pathwidth, complementing the trivial AND-composition that is known for this
problem. In the other direction, we show that OR-cross-compositions into a
parameterized problem can be used to rule out the existence of efficiently
generated quasi-orders on its instances that characterize the NO-instances by
polynomial-size obstructions.


title:
A fast method for implementation of the property lists in programming
  languages

abstract:
  One of the major challenges in programming languages is to support different
data structures and their variations in both static and dynamic aspects. One of
the these data structures is the property list which applications use it as a
convenient way to store, organize, and access standard types of data. In this
paper, the standards methods for implementation of the Property Lists,
including the Static Array, Link List, Hash and Tree are reviewed. Then an
efficient method to implement the property list is presented. The experimental
results shows that our method is fast compared with the existing methods.


title: Efficient Prediction Designs for Random Fields

abstract:
  For estimation and predictions of random fields it is increasingly
acknowledged that the kriging variance may be a poor representative of true
uncertainty. Experimental designs based on more elaborate criteria that are
appropriate for empirical kriging are then often non-space-filling and very
costly to determine. In this paper, we investigate the possibility of using a
compound criterion inspired by an equivalence theorem type relation to build
designs quasi-optimal for the empirical kriging variance, when space-filling
designs become unsuitable. Two algorithms are proposed, one relying on
stochastic optimization to explicitly identify the Pareto front, while the
second uses the surrogate criteria as local heuristic to chose the points at
which the (costly) true Empirical Kriging variance is effectively computed. We
illustrate the performance of the algorithms presented on both a simple
simulated example and a real oceanographic dataset.


title:
SECA: Snapshot-based Event Detection for Checking Asynchronous Context
  Consistency in Ubiquitous Computing

abstract:
  Context-consistency checking is challenging in the dynamic and uncertain
ubiquitous computing environments. This is because contexts are often noisy
owing to unreliable sensing data streams, inaccurate data measurement, fragile
connectivity and resource constraints. One of the state-of-the-art efforts is
CEDA, which concurrently detects context consistency by exploring the
\emph{happened-before} relation among events. However, CEDA is seriously
limited by several side effects --- centralized detection manner that easily
gets down the checker process, heavy computing complexity and false negative.
  In this paper, we propose SECA: Snapshot-based Event Detection for Checking
Asynchronous Context Consistency in ubiquitous computing. SECA introduces
snapshot-based timestamp to check event relations, which can detect scenarios
where CEDA fails. Moreover, it simplifies the logical clock instead of adopting
the vector clock, and thus significantly reduces both time and space
complexity. Empirical studies show that SECA outperforms CEDA in terms of
detection accuracy, scalability, and computing complexity.


title: Supernova constraints on Multi-coupled Dark Energy

abstract:
  The persisting consistency of ever more accurate observational data with the
predictions of the standard LCDM cosmological model puts severe constraints on
possible alternative scenarios, but still does not shed any light on the
fundamental nature of the cosmic dark sector.As large deviations from a LCDM
cosmology are ruled out by data, the path to detect possible features of
alternative models goes necessarily through the definition of cosmological
scenarios that leave almost unaffected the background and -- to a lesser extent
-- the linear perturbations evolution of the universe. In this context,the
Multi-coupled DE (McDE) model was proposed by Baldi 2012 as a particular
realization of an interacting Dark Energy field characterized by an effective
screening mechanism capable of suppressing the effects of the coupling at the
background and linear perturbation level. In the present paper, for the first
time, we challenge the McDE scenario through a direct comparison with real
data, in particular with the luminosity distance of Type Ia supernovae. By
studying the existence and stability conditions of the critical points of the
associated background dynamical system, we select only the cosmologically
consistent solutions, and confront their background expansion history with
data. Confirming previous qualitative results, the McDE scenario appears to be
fully consistent with the adopted sample of Type Ia supernovae, even for
coupling values corresponding to an associated scalar fifth-force about four
orders of magnitude stronger than standard gravity. Our analysis demonstrates
the effectiveness of the McDE background screening, and shows some new
non-trivial asymptotic solutions for the future evolution of the universe. Our
results show how the background expansion history might be highly insensitive
to the fundamental nature and to the internal complexity of the dark sector.
[Abridged]


title:
I Wish I Didn't Say That! Analyzing and Predicting Deleted Messages in
  Twitter

abstract:
  Twitter has become a major source of data for social media researchers. One
important aspect of Twitter not previously considered are {\em deletions} --
removal of tweets from the stream. Deletions can be due to a multitude of
reasons such as privacy concerns, rashness or attempts to undo public
statements. We show how deletions can be automatically predicted ahead of time
and analyse which tweets are likely to be deleted and how.


title:
Search for new physics using events with two same-sign isolated leptons
  in the final state at CMS

abstract:
  We present a search for new physics using events with two same-sign isolated
leptons with/out the presence of b-jets in the final state, targetting two very
different SUSY scenarios, one dominated by strong production of squarks and
gluinos where the 3rd generation squarks are lighter than other squarks and the
other dominated by electroweak production neglecting completely any strongly
interacting particles. No excees above the standard model background is
observed. The results are interpreted in various SUSY models.