title:
The mechanism of quantum chaos manifestations in the spectra of
  singularly perturbed wave-billiard systems

abstract:
  The spectra of a microwave cylindrical resonator with the embedded thin metal
rod playing the role of a singular perturbation are studied both theoretically
and experimentally. The intra- and inter-mode scattering caused by the
perturbation are clearly distinguished and recognized to play essentially
different parts in the appearance of spectrum chaotic properties. The analysis
based on the mode-mixing operator norm shows that the inter-mode scattering
dominates over the intra-mode scattering and basically determines statistical
properties of the resonator spectrum. The results we have obtained in the
experiment are in good conformity with our theory. Clear manifestations of
quantum chaos are revealed for the resonator with the asymmetrically inserted
rod, namely, the Wigner-type distribution of the inter-frequency intervals, the
apparent correlation between spectral lines, and the characteristic curve of
the spectral rigidity. By comparing the theory and the experiment we succeeded
in establishing for the first time that it is just the inter-mode scattering
that is responsible for the quantum chaos manifestations in the singularly
perturbed integrable wave-billiard system.


title:
Non-integrability criterion for homogeneous Hamiltonian systems via
  blowing-up technique of singularities

abstract:
  It is a big problem to distinguish between integrable and non-integrable
Hamiltonian systems. We provide a new approach to prove the non-integrability
of homogeneous Hamiltonian systems with two degrees of freedom.
  The homogeneous degree can be chosen from real values (not necessarily
integer). The proof is based on the blowing-up theory which McGehee established
in the collinear three-body problem. We also compare our result with
Molares-Ramis theory which is the strongest theory in this field.


title:
A Global Wave-Driven MHD Solar Model with a Unified Treatment of Open
  and Closed Magnetic Field Topologies

abstract:
  We describe, analyze and validate the recently developed Alfv\'en Wave Solar
Model (AWSoM), a 3D global model starting from the top of the chromosphere and
extending into interplanetary space (up to 1-2 AU). This model solves the
extended two temperature magnetohydrodynamics equations coupled to a wave
kinetic equation for low frequency Alfv\'en waves. In this picture, heating and
acceleration of the plasma are due to wave dissipation and wave pressure
gradients, respectively. The dissipation process is described by a fully
developed turbulent cascade of counter-propagating waves. We adopt a unified
approach for calculating the wave dissipation in both open and closed magnetic
field lines, allowing for a self-consistent treatment of any magnetic topology.
Wave dissipation is the only heating mechanism assumed in the model, and no
geometric heating functions are invoked. Electron heat conduction and radiative
cooling are also included. We demonstrate that the large-scale, steady-state
(in the co-rotating frame) properties of the solar environment are reproduced,
using three adjustable parameters: the Poynting flux of chromospheric Alfv\'en
waves, the perpendicular correlation length of the turbulence, and a
pseudo-reflection coefficient. We compare model results for Carrington Rotation
2063 (November-December 2007) to remote observations in the EUV and X-ray
ranges from STEREO, SOHO and Hinode spacecraft, as well as to in-situ
measurements performed by Ulysses. The model results are in good agreement with
observations. This is the first global model capable of simultaneously
reproducing the multi-wavelength observations of the lower corona and the wind
structure beyond Earth's orbit.


title:
Influence of nuclear interactions in polyethylene range compensators for
  carbon-ion radiotherapy

abstract:
  \item[Purpose] A recent study revealed that polyethylene (PE) would cause
extra carbon-ion attenuation per range shift by 0.45\%/cm due to compositional
differences in nuclear interactions. The present study aims to assess the
influence of PE range compensators on tumor dose in carbon-ion radiotherapy.
\item[Methods] Carbon-ion radiation was modeled to be composed of primary
carbon ions and secondary particles, for each of which the dose and the
relative biological effectiveness (RBE) were estimated at a tumor depth in the
middle of spread-out Bragg peak. Assuming exponential behavior for attenuation
and yield of these components with depth, the PE effect on dose was calculated
for clinical carbon-ion beams and was partly tested by experiment. The
two-component model was integrated into a treatment-planning system and the PE
effect was estimated in two clinical cases. \item[Results] The attenuation per
range shift by PE was 0.1\%--0.3\%/cm in dose and 0.2\%--0.4\%/cm in
RBE-weighted dose, depending on energy and range-modulation width. This
translates into reduction of RBE-weighted dose by up to 3\% in extreme cases.
In the treatment-planning study, however, the effect on RBE-weighted dose to
tumor was typically within 1\% reduction. \item[Conclusions] The extra
attenuation of primary carbon ions in PE was partly compensated by increased
secondary particles for tumor dose. In practical situations, the PE range
compensators would normally cause only marginal errors as compared to intrinsic
uncertainties in treatment planning, patient setup, beam delivery, and clinical
response.


title: Stabilization of betatron tune in Indus-2

abstract:
  Indus-2 is a synchrotron radiation source which is operational at RRCAT,
Indore; India. It is essentially pertinent in any synchrotron radiation
facility to store the electron beam without beam loss. During the day to day
operation of Indus-2 storage ring difficulty was being faced in accumulating
higher beam current. After examining, it was found that the working point was
shifting from its desired value during accumulation. For smooth beam
accumulation, a fixed desired tune in both horizontal and vertical plane plays
a great role in avoiding the beam loss via resonance process. This demanded a
betatron tune feedback system to be put in storage ring and after putting ON
this feedback, the beam accumulation was smooth. The details of this feedback
and its working principle are described in this paper.


title: Effective field theory of interactions on the lattice

abstract:
  We consider renormalization of effective field theory interactions by
discretizing the continuum on a tight-binding lattice. After studying the
one-dimensional problem, we address s-wave collisions in three dimensions and
relate the bare lattice coupling constants to the continuum coupling constants.
Our method constitutes a very simple avenue for the systematic renormalization
in effective field theory, and is especially useful as the number of
interaction parameters increases.


title: Supervised Metric Learning with Generalization Guarantees

abstract:
  The crucial importance of metrics in machine learning algorithms has led to
an increasing interest in optimizing distance and similarity functions, an area
of research known as metric learning. When data consist of feature vectors, a
large body of work has focused on learning a Mahalanobis distance. Less work
has been devoted to metric learning from structured objects (such as strings or
trees), most of it focusing on optimizing a notion of edit distance. We
identify two important limitations of current metric learning approaches.
First, they allow to improve the performance of local algorithms such as
k-nearest neighbors, but metric learning for global algorithms (such as linear
classifiers) has not been studied so far. Second, the question of the
generalization ability of metric learning methods has been largely ignored. In
this thesis, we propose theoretical and algorithmic contributions that address
these limitations. Our first contribution is the derivation of a new kernel
function built from learned edit probabilities. Our second contribution is a
novel framework for learning string and tree edit similarities inspired by the
recent theory of (e,g,t)-good similarity functions. Using uniform stability
arguments, we establish theoretical guarantees for the learned similarity that
give a bound on the generalization error of a linear classifier built from that
similarity. In our third contribution, we extend these ideas to metric learning
from feature vectors by proposing a bilinear similarity learning method that
efficiently optimizes the (e,g,t)-goodness. Generalization guarantees are
derived for our approach, highlighting that our method minimizes a tighter
bound on the generalization error of the classifier. Our last contribution is a
framework for establishing generalization bounds for a large class of existing
metric learning algorithms based on a notion of algorithmic robustness.


title:
Centrality dependence of light (anti)nuclei and (anti)hypertriton
  production in Au+Au collisions at $\sqrt{s_{\rm{NN}}}$ = 200 GeV

abstract:
  We have used the dynamically constrained phase space coalescence model to
investigate the centrality dependence of light (anti)nuclei and
(anti)hypertriton production based on the $6.2\times 10^7$ hadronic final
states generated by the PACIAE model in Au+Au collisions at
$\sqrt{s_{\rm{NN}}}=200$ GeV in $|y| <1$ and $p_T<5$ acceptances. It turned out
that the yields of light (anti)nuclei and (anti)hypertriton strongly depend on
the centrality, i.e. their yields decrease rapidly with the increase of
centrality bins; but their yield ratios are independent on centrality. These
theoretical results are consistent with the STAR and PHENIX data. Furthermore,
centrality distribution of $d$ ($\bar d$), $^3{He}$ ($^3{\bar{He}}$) and
$_{\bar\Lambda}^3H$ ($\bar{_{\bar\Lambda}^3H}$) follows Gaussian distributions.
This means that light (anti)nuclei and (anti)hypertriton are primarily produced
in the central collisions.


title: Mammogram Edge Detection Using Hybrid Soft Computing Methods

abstract:
  Image segmentation is a crucial step in a wide range of method image
processing systems. It is useful in visualization of the different objects
present in the image. In spite of the several methods available in the
literature, image segmentation still a challenging problem in most of image
processing applications. The challenge comes from the fuzziness of image
objects and the overlapping of the different regions. Detection of edges in an
image is a very important step towards understanding image features. There are
large numbers of edge detection operators available, each designed to be
sensitive to certain types of edges. The Quality of edge detection can be
measured from several criteria objectively. Some criteria are proposed in terms
of mathematical measurement, some of them are based on application and
implementation requirements. Since edges often occur at image locations
representing object boundaries, edge detection is extensively used in image
segmentation when images are divided into areas corresponding to different
objects. This can be used specifically for enhancing the tumor area in
mammographic images. Different methods are available for edge detection like
Roberts, Sobel, Prewitt, Canny, Log edge operators. In this paper a novel
algorithms for edge detection has been proposed for mammographic images. Breast
boundary, pectoral region and tumor location can be seen clearly by using this
method. For comparison purpose Roberts, Sobel, Prewitt, Canny, Log edge
operators are used and their results are displayed. Experimental results
demonstrate the effectiveness of the proposed approach.


title: Delayed Energy Injection Model For Gamma-Ray Burst Afterglows

abstract:
  The shallow decay phase and flares in the afterglows of gamma-ray bursts
(GRBs) is widely believed to be associated with the later activation of central
engine. Some models of energy injection involve with a continuous energy flow
since the GRB trigger time, such as the magnetic dipole radiation from a
magnetar. However, in the scenario involving with a black hole accretion
system, the energy flow from the fall-back accretion may be delayed for a
fall-back time $\sim t_{\rm fb}$. Thus we propose a delayed energy injection
model, the delayed energy would cause a notable rise to the Lorentz factor of
the external shock, which will "generate" a bump in the multiple band
afterglows. If the delayed time is very short, our model degenerates to the
previous models. Our model can well explain the significant re-brightening in
the optical and infrared light curves of GRB 081029 and GRB 100621A. A
considerable fall-back mass is needed to provide the later energy, this
indicates GRBs accompanied with fall-back material may be associated with a low
energy supernova so that fraction of the envelope can be survived during
eruption. The fall-back time can give meaningful information of the properties
of GRB progenitor stars.


title: Ranking with Diverse Intents and Correlated Contents

abstract:
  We consider the following document ranking problem: We have a collection of
documents, each containing some topics (e.g. sports, politics, economics). We
also have a set of users with diverse interests. Assume that user u is
interested in a subset I_u of topics. Each user u is also associated with a
positive integer K_u, which indicates that u can be satisfied by any K_u topics
in I_u. Each document s contains information for a subset C_s of topics. The
objective is to pick one document at a time such that the average satisfying
time is minimized, where a user's satisfying time is the first time that at
least K_u topics in I_u are covered in the documents selected so far. Our main
result is an O({\rho})-approximation algorithm for the problem, where {\rho} is
the algorithmic integrality gap of the linear programming relaxation of the set
cover instance defined by the documents and topics. This result generalizes the
constant approximations for generalized min-sum set cover and ranking with
unrelated intents and the logarithmic approximation for the problem of ranking
with submodular valuations (when the submodular function is the coverage
function), and can be seen as an interpolation between these results. We
further extend our model to the case when each user may interest in more than
one sets of topics and when the user's valuation function is XOS, and obtain
similar results for these models.


title:
Extending the ER Model to relational Model novel transformation
  Algorithm: transforming relationship Types among Subtypes

abstract:
  A novel approach for creating ER conceptual models and an algorithm for
transforming them to the relational model has been developed by modifying and
extending the existing methods. A part of the new algorithm has previously been
presented. This paper presents the rest of the algorithm. One of the objectives
of this paper is to use it as a supportive document for ongoing empirical
evaluations of the new approach being conducted using the cognitive engagement
method and with the participation of different segments of the field as
respondents.


title:
Mixing-Demixing Phase Diagram for Simple Liquids in Non-Uniform Electric
  Fields

abstract:
  We deduce the mixing-demixing phase diagram for binary liquid mixtures in an
electric field for various electrode geometries and arbitrary constitutive
relation for the dielectric constant. By focusing on the behavior of the
liquid-liquid interface, we produce simple analytic expressions for the
dependence of the interface location on experimental parameters. We also show
that the phase diagram contains regions where liquid separation cannot occur
under any applied field. The analytic expression for the boundary
"electrostatic binodal" line reveals that the regions' size and shape depend
strongly on the dielectric relation between the liquids. Moreover, we predict
the existence of an "electrostatic spinodal" line that identifies conditions
where the liquids are in a metastable state. We finally construct the phase
diagram for closed systems by mapping solutions onto those of an open system
via an effective liquid composition. For closed systems at a fixed temperature
and mixture composition, liquid separation occurs in a finite "window" of
surface potential (or charge density). Larger potentials or charge densities
counterintuitively destroy the interface, leading to liquid mixing. These
results give valuable guides for experiments by providing easily testable
predictions for how liquids behave in non-uniform electric fields.


title:
Bottleneck combinatorial optimization problems with uncertain costs and
  the OWA criterion

abstract:
  In this paper a class of bottleneck combinatorial optimization problems with
uncertain costs is discussed. The uncertainty is modeled by specifying a
discrete scenario set containing a finite number of cost vectors, called
scenarios. In order to choose a solution the Ordered Weighted Averaging
aggregation operator (shortly OWA) is applied. The OWA operator generalizes
traditional criteria in decision making under uncertainty such as the maximum,
minimum, average, median, or Hurwicz criterion. New complexity and
approximation results in this area are provided. These results are general and
remain valid for many problems, in particular for a wide class of network
problems.


title: A diagrammatic categorification of the fermion algebra

abstract:
  In this paper, we study the diagrammatic categorification of the fermion
algebra. We construct a graphical category corresponding to the one-dimensional
fermion algebra, and we investigate the properties of this category. The
categorical analogues of the Fock states are some kind of 1-morphisms in our
category, and the dimension of the vector space of 2-morphisms is exactly the
inner product of the corresponding Fock states. All the results in our
categorical framework coincide exactly with those in normal quantum mechanics.


title: Extended Gravity: State of the Art and Perspectives

abstract:
  We shortly review the state of art and perspectives of Extended Theories of
Gravity.


title: Weak values and weak coupling maximizing the output of weak measurements

abstract:
  In a weak measurement, the average output $\langle o\rangle$ of a probe that
measures an observable $\hat{A}$ of a quantum system undergoing both a
preparation in a state $\rho_i$ and a postselection in a state $E_\mathrm{f}$
is, to a good approximation, a function of the weak value $A_w=\mathrm{Tr} [E_f
\hat{A} \rho_i]/\mathrm{Tr}[E_f\rho_i]$, a complex number. For a fixed coupling
$\lambda$, when the overlap $\mathrm{Tr}[E_f\rho_i]$ is very small, $A_w$
diverges, but $\langle o\rangle$ stays finite, often tending to zero for
symmetry reasons. This paper answers the questions: what is the weak value that
maximizes the output for a fixed coupling? what is the coupling that maximizes
the output for a fixed weak value? We derive equations for the optimal values
of $A_w$ and $\lambda$, and provide the solutions. The results are independent
of the dimensionality of the system, and they apply to a probe having a Hilbert
space of arbitrary dimension. Using the Schr\"{o}dinger-Robertson uncertainty
relation, we demonstrate that, in an important case, the amplification $\langle
o\rangle$ cannot exceed the initial uncertainty $\sigma_o$ in the observable
$\hat{o}$, we provide an upper limit for the more general case, and a strategy
to obtain $\langle o\rangle\gg \sigma_o$.


title: Conductors of l-adic representations

abstract:
  We give a new formula for the Artin conductor of an $\ell$-adic
representation of the Weil group of a local field of residue characteristic
$p\neq\ell$.


title:
Exclusive J/{\psi} production in ultraperipheral collisions at the LHC:
  constrains on the gluon distributions in the proton and nuclei

abstract:
  Using the framework of collinear factorization in perturbative QCD (pQCD), we
analyze the recent data of the LHCb and ALICE collaborations on exclusive
photoproduction of J/{\psi} in ultraperipheral pp and AA collisions,
respectively. We demonstrate that the simultaneous analysis of the proton and
Pb data allows us to reduce the ambiguity of the pQCD description of the
$\gamma p \to J/\psi p$ and $\gamma A \to J/\psi p$ cross sections and, hence,
to place additional constraints on the gluon distributions in the nucleon and
nuclei at small x. We also make predictions for the cross section of coherent
exclusive photoproduction of J/{\psi} in nucleus-nucleus ultraperipheral
collisions accompanied by the electromagnetic excitation of nuclei and the
subsequent neutron emission.


title: Imaging coronal magnetic-field reconnection in a solar flare

abstract:
  Magnetic-field reconnection is believed to play a fundamental role in
magnetized plasma systems throughout the Universe1, including planetary
magnetospheres, magnetars and accretion disks around black holes. This letter
present extreme ultraviolet and X-ray observations of a solar flare showing
magnetic reconnection with a level of clarity not previously achieved. The
multi-wavelength extreme ultraviolet observations from SDO/AIA show inflowing
cool loops and newly formed, outflowing hot loops, as predicted. RHESSI X-ray
spectra and images simultaneously show the appearance of plasma heated to >10
MK at the expected locations. These two data sets provide solid visual evidence
of magnetic reconnection producing a solar flare, validating the basic physical
mechanism of popular flare models. However, new features are also observed that
need to be included in reconnection and flare studies, such as
three-dimensional non-uniform, non-steady and asymmetric evolution.


title:
Sorption of 4He, H2, Ne, N2, CH4 and Kr impurities in graphene oxide at
  low temperatures. Quantum effects

abstract:
  Sorption and the subsequent desorption of 4He, H2,Ne, N2, CH4 and Kr gas
impurities by graphene oxide (GO), glucose-reduced GO (RGO-Gl) and
hydrazine-reduced GO (RGO-Hz) powders have been investigated in the temperature
interval 2-290 K. It has been found that the sorptive capacity of the reduced
sample RGO-Hz is three to six times higher than that of GO. The reduction of GO
with glucose has only a slight effect on its sorptive properties. The
temperature dependences of the diffusion coefficients of the GO, RGO-Gl and
RGO-Hz samples have been obtained using the measured characteristic times of
sorption. It is assumed that the temperature dependences of the diffusion
coefficients are determined by the competition of the thermally activated and
tunneling mechanisms, the tunneling contribution being dominant at low
temperatures.


title:
Monte Carlo simulation with aspect ratio optimization: Anomalous
  anisotropic scaling in dimerized antiferromagnet

abstract:
  We present a method that optimizes the aspect ratio of a spatially
anisotropic quantum lattice model during the quantum Monte Carlo simulation,
and realizes the virtually isotropic lattice automatically. The anisotropy is
removed by using the Robbins-Monro algorithm based on the correlation length in
each direction. The method allows for comparing directly the value of critical
amplitude among different anisotropic models, and identifying the universality
more precisely. We apply our method to the staggered dimer antiferromagnetic
Heisenberg model and demonstrate that the apparent non-universal behavior is
attributed mainly to the strong size correction of the effective aspect ratio
due to the existence of the cubic interaction.


title: Local translations associated to spectral sets

abstract:
  In connection to the Fuglede conjecture, we study groups of local
translations associated to spectral sets, i.e., measurable sets in $\br$ or
$\bz$ that have an orthogonal basis of exponential functions. We investigate
the connections between the groups of local translations on $\bz$ and on $\br$
and present some examples for low cardinality. We present some relations
between the group of local translations and tilings.


title:
Crowd-assisted Search for Price Discrimination in E-Commerce: First
  results

abstract:
  After years of speculation, price discrimination in e-commerce driven by the
personal information that users leave (involuntarily) online, has started
attracting the attention of privacy researchers, regulators, and the press. In
our previous work we demonstrated instances of products whose prices varied
online depending on the location and the characteristics of perspective online
buyers. In an effort to scale up our study we have turned to crowd-sourcing.
Using a browser extension we have collected the prices obtained by an initial
set of 340 test users as they surf the web for products of their interest. This
initial dataset has permitted us to identify a set of online stores where price
variation is more pronounced. We have focused on this subset, and performed a
systematic crawl of their products and logged the prices obtained from
different vantage points and browser configurations. By analyzing this dataset
we see that there exist several retailers that return prices for the same
product that vary by 10%-30% whereas there also exist isolated cases that may
vary up to a multiplicative factor, e.g., x2. To the best of our efforts we
could not attribute the observed price gaps to currency, shipping, or taxation
differences.


title:
Xing-Ling Codes, Duals of their Subcodes, and Good Asymmetric Quantum
  Codes

abstract:
  A class of powerful $q$-ary linear polynomial codes originally proposed by
Xing and Ling is deployed to construct good asymmetric quantum codes via the
standard CSS construction. Our quantum codes are $q$-ary block codes that
encode $k$ qudits of quantum information into $n$ qudits and correct up to
$\flr{(d_{x}-1)/2}$ bit-flip errors and up to $\flr{(d_{z}-1)/2}$ phase-flip
errors.. In many cases where the length $(q^{2}-q)/2 \leq n \leq (q^{2}+q)/2$
and the field size $q$ are fixed and for chosen values of $d_{x} \in
\{2,3,4,5\}$ and $d_{z} \ge \delta$, where $\delta$ is the designed distance of
the Xing-Ling (XL) codes, the derived pure $q$-ary asymmetric quantum CSS codes
possess the best possible size given the current state of the art knowledge on
the best classical linear block codes.


title:
A New Multi-wavelength Solar Telescope: Optical and Near-infrared Solar
  Eruption Tracer (ONSET)

abstract:
  A new multi-wavelength solar telescope, Optical and Near-infrared Solar
Eruption Tracer (ONSET) of Nanjing University, was constructed, being
fabricated by Nanjing Institute of Astronomical Optics & Technology and run in
cooperation with Yunnan Astronomical Observatory. ONSET is able to observe the
Sun in three wavelength windows: He {\small I} 10830 \AA, H$\alpha$, and
white-light at 3600 \AA and 4250 \AA, which are selected in order to obtain the
dynamics in the corona, chromosphere, and the photosphere simultaneously.
Full-disk or partial-disk solar images with a field of 10 arcmin at three
wavelengths can be obtained nearly simultaneously. It is designed to trace
solar eruptions with high spatial and temporal resolutions. This telescope was
installed at a new solar observing site near Fuxian Lake in Yunnan Province,
southwest China. The site is located at E102N24, with an altitude of 1722 m.
The seeing is stable and of high quality. We give a brief description of the
scientific objectives and the basic structure of the ONSET. Some preliminary
results are also presented.


title: Enrico : a Python package to simplify Fermi-LAT analysis

abstract:
  With the advent of the Large Array Telescope (LAT) on board the Fermi
satellite, a new window on the Universe has been opened. Publicly available,
the Fermi-LAT data come together with an analysis software named ScienceTools
(ST, http://fermi.gsfc.nasa.gov/ssc/data/analysis/software/) which can be run
through a Python interface. Nevertheless, for the user, the ST can be hard to
run and imply several steps. Users already contributed with scripts for a
specific task but no tool allowing a complete analysis is currently available.
  We present a Python package called {\tt Enrico}, designed to facilitate the
data analysis. Using only configuration files and front end tools from the
command line, the user can easily perform/reproduce an entire Fermi analysis
and make plots for publications. It also include new features like debug plots,
pipeline execution on one or several CPUs, downloading of the Fermi data or the
generation of a sky model from the Fermi catalogue.
  {\tt Enrico} is an open-source project currently available for download at
\url{https://github.com/gammapy/enrico}


title:
The location and impact of jet-driven outflows of cold gas: the case of
  3C293

abstract:
  The nearby radio galaxy 3C293 is one of a small group of objects where
extreme outflows of neutral hydrogen have been detected. However, due to the
limited spatial resolution of previous observations, the exact location of the
outflow was not able to be determined. In this letter, we present new higher
resolution VLA observations of the central regions of this radio source and
detect a fast outflow of HI with a FWZI velocity of \Delta v~1200 km/s
associated with the inner radio jet, approximately 0.5 kpc west of the central
core. We investigate possible mechanisms which could produce the observed HI
outflow and conclude that it is driven by the radio-jet. However, this outflow
of neutral hydrogen is located on the opposite side of the nucleus to the
outflow of ionised gas previously detected in this object. We calculate a mass
outflow rate in the range of 8-50 solar masses/yr corresponding to a kinetic
energy power injected back into the ISM of 1.38x10^{42} - 1.00x10^{43} erg/s or
0.01 - 0.08 percent of the Eddington luminosity. This places it just outside
the range required by some galaxy evolution simulations for negative feedback
from the AGN to be effective in halting star-formation within the galaxy.


title: Defect scaling Lee-Yang model from the perturbed DCFT point of view

abstract:
  We analyze the defect scaling Lee-Yang model from the perturbed defect
conformal field theory (DCFT) point of view. First the defect Lee-Yang model is
solved by calculating its structure constants from the sewing relations.
Integrable defect perturbations are identified in conformal defect perturbation
theory. Then pure defect flows connecting integrable conformal defects are
described. We develop a defect truncated conformal space approach (DTCSA) to
analyze the one parameter family of integrable massive perturbations in finite
volume numerically. Fusing the integrable defect to an integrable boundary the
relation between the IR and UV parameters can be derived from the boundary
relations. We checked these results by comparing the spectrum for large volumes
to the scattering theory.


title: The Straw Tube Trackers of the PANDA Experiment

abstract:
  The PANDA experiment will be built at the FAIR facility at Darmstadt
(Germany) to perform accurate tests of the strong interaction through bar pp
and bar pA annihilation's studies. To track charged particles, two systems
consisting of a set of planar, closed-packed, self-supporting straw tube layers
are under construction. The PANDA straw tubes will have also unique
characteristics in term of material budget and performance. They consist of
very thin mylar-aluminized cathodes which are made self-supporting by means of
the operation gas-mixture over-pressure. This solution allows to reduce at
maximum the weight of the mechanical support frame and hence the detector
material budget. The PANDA straw tube central tracker will not only reconstruct
charged particle trajectories, but also will help in low momentum (< 1 GeV)
particle identification via dE/dx measurements. This is a quite new approach
that PANDA tracking group has first tested with detailed Monte Carlo
simulations, and then with experimental tests of detector prototypes. This
paper addresses the design issues of the PANDA straw tube trackers and the
performance obtained in prototype tests.


title:
Superprocesses as models for information dissemination in the Future
  Internet

abstract:
  Future Internet will be composed by a tremendous number of potentially
interconnected people and devices, offering a variety of services, applications
and communication opportunities. In particular, short-range wireless
communications, which are available on almost all portable devices, will enable
the formation of the largest cloud of interconnected, smart computing devices
mankind has ever dreamed about: the Proximate Internet. In this paper, we
consider superprocesses, more specifically super Brownian motion, as a suitable
mathematical model to analyse a basic problem of information dissemination
arising in the context of Proximate Internet. The proposed model provides a
promising analytical framework to both study theoretical properties related to
the information dissemination process and to devise efficient and reliable
simulation schemes for very large systems.


title:
Spatial Fluctuations Of Fluid Velocities In Flow Through A
  Three-Dimensional Porous Medium

abstract:
  We use confocal microscopy to directly visualize the spatial fluctuations in
fluid flow through a three-dimensional porous medium. We find that the velocity
magnitudes and the velocity components both along and transverse to the imposed
flow direction are exponentially distributed, even with residual trapping of a
second immiscible fluid. Moreover, we find pore-scale correlations in the flow
that are determined by the geometry of the medium. Our results suggest that,
despite the considerable complexity of the pore space, fluid flow through it is
not completely random.

categories: cond-mat.soft cond-mat.dis-nn cond-mat.mes-hall physics.flu-dyn physics.geo-ph


title:
Mechanics and cooling system for the camera of the Large Size Telescopes
  of the Cherenkov Telescope Array (CTA)

abstract:
  Mechanics of the camera for the large size telescopes of CTA must protect and
provide a stable environment for its instrumentation. This is achieved by a
stiff support structure enclosed in an air and water tight volume. The
structure is specially devised to facilitate extracting the power dissipated by
the focal plane electronics while keeping its weight small enough to guarantee
an optimum load on the telescope structure. A heat extraction system is
designed to keep the electronics temperature within its optimal operation
range, stable in time and homogeneous along the camera volume, whereas it is
decoupled from the temperature in the telescope environment. In this
contribution, we present the details of this system as well as its verification
based in finite element analysis computations and tested prototypes. Finally,
issues related to the integration of the camera mechanics and electronics will
be dealt with.


title:
The resilience of interdependent transportation networks under targeted
  attack

abstract:
  Modern world builds on the resilience of interdependent infrastructures
characterized as complex networks. Recently, a framework for analysis of
interdependent networks has been developed to explain the mechanism of
resilience in interdependent networks. Here we extend this interdependent
network model by considering flows in the networks and study the system's
resilience under different attack strategies. In our model, nodes may fail due
to either overload or loss of interdependency. Under the interaction between
these two failure mechanisms, it is shown that interdependent scale-free
networks show extreme vulnerability. The resilience of interdependent SF
networks is found in our simulation much smaller than single SF network or
interdependent SF networks without flows.


title:
Quadrupole--octopole alignment of CMB related to primordial power
  spectrum with dipolar modulation in anisotropic spacetime

abstract:
  The WMAP and Planck observations show that the quadrupole and octopole
orientations of the CMB might align with each other. We reveal that the
quadrupole--octopole alignment is a natural implication of the primordial power
spectrum in an anisotropic spacetime. The primordial power spectrum is
presented with a dipolar modulation. We obtain the privileged plane by
employing the ``power tensor'' technique. At this plane, there is the maximum
correlation between quadrupole and octopole. The probability for the alignment
is much larger than what in the isotropic universe. We find that this model
would lead to deviations from the statistical isotropy only for low--\(\ell\)
multipoles.


title: Complete Solutions for a Combinatorial Puzzle in Linear Time

abstract:
  In this paper we study a single player game consisting of $n$ black checkers
and $m$ white checkers, called shifting the checkers. We have proved that the
minimum number of steps needed to play the game for general $n$ and $m$ is $nm
+ n + m$. We have also presented an optimal algorithm to generate an optimal
move sequence of the game consisting of $n$ black checkers and $m$ white
checkers, and finally, we present an explicit solution for the general game.


title: Abrupt transition in the structural formation of interconnected networks

abstract:
  Our current world is linked by a complex mesh of networks where information,
people and goods flow. These networks are interdependent each other, and
present structural and dynamical features different from those observed in
isolated networks. While examples of such "dissimilar" properties are becoming
more abundant, for example diffusion, robustness and competition, it is not yet
clear where these differences are rooted in. Here we show that the composition
of independent networks into an interconnected network of networks undergoes a
structurally sharp transition as the interconnections are formed. Depending of
the relative importance of inter and intra-layer connections, we find that the
entire interdependent system can be tuned between two regimes: in one regime,
the various layers are structurally decoupled and they act as independent
entities; in the other regime, network layers are indistinguishable and the
whole system behave as a single-level network. We analytically show that the
transition between the two regimes is discontinuous even for finite size
networks. Thus, any real-world interconnected system is potentially at risk of
abrupt changes in its structure that may reflect in new dynamical properties.


title: The NectarCAM camera project

abstract:
  In the framework of the next generation of Cherenkov telescopes, the
Cherenkov Telescope Array (CTA), NectarCAM is a camera designed for the medium
size telescopes covering the central energy range of 100 GeV to 30 TeV.
NectarCAM will be finely pixelated (~ 1800 pixels for a 8 degree field of view,
FoV) in order to image atmospheric Cherenkov showers by measuring the charge
deposited within a few nanoseconds time-window. It will have additional
features like the capacity to record the full waveform with GHz sampling for
every pixel and to measure event times with nanosecond accuracy. An array of a
few tens of medium size telescopes, equipped with NectarCAMs, will achieve up
to a factor of ten improvement in sensitivity over existing instruments in the
energy range of 100 GeV to 10 TeV. The camera is made of roughly 250
independent read-out modules, each composed of seven photo-multipliers, with
their associated high voltage base and control, a read-out board and a
multi-service backplane board. The read-out boards use NECTAr (New Electronics
for the Cherenkov Telescope Array) ASICs which have the dual functionality of
analogue memories and Analogue to Digital Converter (ADC). The camera trigger
to be used will be flexible so as to minimize the read-out dead-time of the
NECTAr chips. We present the camera concept and the design and tests of the
various subcomponents. The design includes the mechanical parts, the cooling of
the electronics, the readout, the data acquisition, the trigger, the monitoring
and services.


title: Thermodynamic arrow of time of quantum projective measurements

abstract:
  We investigate a thermodynamic arrow associated with quantum projective
measurements in terms of the Jensen-Shannon divergence between the probability
distribution of energy change caused by the measurements and its time reversal
counterpart. Two physical quantities appear to govern the asymptotic values of
the time asymmetry. For an initial equilibrium ensemble prepared at a high
temperature, the energy fluctuations determine the convergence of the time
asymmetry approaching zero. At low temperatures, finite survival probability of
the ground state limits the time asymmetry to be less than $\ln 2$. We
illustrate our results for a concrete system and discuss the fixed point of the
time asymmetry in the limit of infinitely repeated projections.


title:
Effective Action and Field Equation for BEC from Weak to Strong
  Couplings

abstract:
  While free and weakly interacting nonrelativistic particles are described by
a Gross-Pitaevskii equation, which is a nonlinear self-interacting
Schr\"odinger equation, the phenomena in the strong- coupling limit are
governed by an effective action that is extremized by a double-fractional
generalization of this equation. Its particle orbits perform L\`evy walks
rather than Gaussian random walks.


title:
Low-amplitude magnetic vortex core reversal by non-linear interference
  between azimuthal spin waves and the vortex gyromode

abstract:
  We demonstrate a non-linear interference due to an active 'dual frequency'
excitation of both, the sub-GHz vortex gyromode and multi-GHz magneto-static
spin waves in ferromagnetic micrometer sized platelets in the vortex state.
When the sub-GHz vortex gyromode is excited simultaneously a significant
broadband reduction of the switching threshold for spin wave mediated vortex
core reversal is observed in both, experiments and micromagnetic simulations.
Consequently, the magnetic field amplitudes required for vortex core reversal
can be lowered by nearly one order of magnitude. Moreover, additional spin wave
resonance frequencies are found which emerge only if the vortex gyromode is
actively excited simultaneously which can be explained by frequency doubling
and by the broken symmetry of the vortex state.


title:
Hund and pair-hopping signature in transport properties of degenerate
  nanoscale devices

abstract:
  We investigate the signature of a complete Coulomb interaction in transport
properties of double-orbital nanoscale devices. We analyze the specific effects
of Hund exchange and pair hopping terms, calculating in particular stability
diagrams. It turns out that a crude model, with partial Coulomb interaction,
may lead to a misinterpretation of experiments. In addition, it is shown that
spectral weight transfers induced by gate and bias voltages strongly influence
charge current. The low temperature regime is also investigated, displaying
inelastic cotunneling associated with the exchange term, as well as Kondo
conductance enhancement.


title: Commissioning and initial performance of the H.E.S.S. II drive system

abstract:
  The H.E.S.S. observatory was recently extended with a fifth telescope located
at the center of the array - H.E.S.S. II. With a reflector roughly six times
the area of the smaller telescopes and four times more pixels per sky area,
this new telescope can resolve images of particle showers in the atmosphere in
unprecedented detail and explore the gamma-ray sky in the poorly studied regime
around a few tens of Giga electron-volt.
  H.E.S.S. II has been equipped with a high-performance drive system that can
deliver the high torque necessary to accelerate and slew the 600 tonnes
telescope while keeping a good tracking accuracy. A modular design with a high
degree of redundancy has been employed to achieve stability of operation and to
ensure that the telescope can be moved to a safe position within a short period
of time. Each axis is driven by four 28 kW servo motors which are pair-wise
torque-biased and synchronized through a state of the art Programmable Logic
Controller (PLC). With this system, a fast repositioning and a minimal settling
time has been achieved - crucial when studying transient sources such as
gamma-ray bursts which are a prime target for this telescope.
  This contribution will report on the successful commissioning of the H.E.S.S.
II drive system in the first half of 2012 at the H.E.S.S. site in Namibia. The
technical implementation and the performance of the drive system will be
presented.


title: Inclusive semileptonic fits, heavy quark masses, and V_cb

abstract:
  We perform global fits to the moments of semileptonic B decay distributions
and extract |V_cb|, the heavy quark masses, and the non-perturbative parameters
of the heavy quark expansion. We include NNLO perturbative corrections and
recent determinations of the charm mass, and discuss how they improve the
precision of the global fit. In particular, using the m_c determination of
Ref.[11] we get m_b^kin=4.541(23) GeV and |V_cb|=(42.42+- 0.86) 10^{-3}. We
also discuss the implications of the new fits for the normalization of rare B
decays, the zero-recoil sum rule in B-> D* l nu, and the inclusive
determination of |V_ub|.


title: Quintessential power-law cosmology: dark energy equation of state

abstract:
  Power-law cosmology with scale factor as power of cosmic time, $a \propto
t^{\a}$, is investigated. We review and discuss value of $\a$ obtained from
various types of observation. Considering dark energy dominant era in late
universe from $z < 0.5$, we use observational derived results from Cosmic
Microwave Background (WMAP7), Baryon Acoustic Oscillations (BAO) and
observational Hubble data to find power exponent $\a$ and other cosmological
variables. $\a$ is found to be $0.99 \pm 0.02$ (WMAP7+BAO+$H_0$) and $0.99 \pm
0.04$ (WMAP7). These values do not exclude possibility of acceleration at
1$\sigma$ hence giving viability to power-law cosmology in general. When
considering scenario of canonical scalar field dark energy with power-law
cosmology, we derive scalar field potential, exact scalar field solution and
equation of state parameter. We found that the scenario of power-law cosmology
containing dynamical canonical scalar field predicts present equation of state
parameter $w_{\phi, 0} = -0.449 \pm 0.030 $ while the $w$CDM with WMAP7 data
(model independent, $w$ constant) allows a maximum (+1$\sigma$) value of
$w_{\phi, 0}$ at -0.70 which is off the prediction range. However, in case of
varying $w_{\phi}$, the $w_{\phi, 0}$ value predicted from quintessential
power-law cosmology is allowed within 1$\sigma$ uncertainty.


title: Tail Behaviour of Mexican Needlets

abstract:
  In this paper we study the tail behaviour of Mexican needlets, a class of
spherical wavelets introduced by Geller and Mayeli (2009). More specifically,
we provide an explicit upper bound depending on the resolution level $j$ and a
parameter $s$ governing the shape of the Mexican needlets


title: Creative Telescoping for Holonomic Functions

abstract:
  The aim of this article is twofold: on the one hand it is intended to serve
as a gentle introduction to the topic of creative telescoping, from a practical
point of view; for this purpose its application to several problems is
exemplified. On the other hand, this chapter has the flavour of a survey
article: the developments in this area during the last two decades are sketched
and a selection of references is compiled in order to highlight the impact of
creative telescoping in numerous contexts.


title:
Search for Very-high-energy gamma-ray emission from Galactic globular
  clusters with H.E.S.S

abstract:
  Globular clusters (GCs) are established emitters of high-energy (HE, 100
MeV<E<100 GeV) \gamma-ray radiation which could originate from the cumulative
emission of the numerous millisecond pulsars (msPSRs) in the clusters' cores or
from inverse Compton (IC) scattering of relativistic leptons accelerated in the
GC environment. GCs could also constitute a new class of sources in the
very-high-energy (VHE, E>100 GeV) \gamma-ray regime, judging from the recent
detection of emission from the direction of Terzan 5 with the H.E.S.S.
telescope array.
  To search for VHE \gamma-ray sources associated with other GCs, and to put
constraints on leptonic emission models, we systematically analyzed the
observations towards 15 GCs taken with H.E.S.S. We searched for individual
sources of VHE \gamma-rays from each GC in our sample and also performed a
stacking analysis combining the data from all GCs to investigate the hypothesis
of a population of faint emitters. Assuming IC emission as the source of
emission from Terzan 5, we calculated the expected \gamma-ray flux for each of
the 15 GCs, based on their number of millisecond pulsars, their optical
brightness and the energy density of background photon fields.
  We did not detect significant emission from any of the 15 GCs. The obtained
flux upper limits allow to rule out the simple IC/msPSR scaling model for NGC
6388 and NGC 7078. The upper limits derived from the stacking analyses are
factors between 2 and 50 below the flux predicted by the simple leptonic model,
depending on the assumed source extent and the dominant target photon fields.
Therefore, Terzan 5 still remains exceptional among all GCs, as the VHE
\gamma-ray emission either arises from extra-ordinarily efficient leptonic
processes, or from a recent catastrophic event, or is even unrelated to the GC
itself.


title:
Study of $D_J$ meson decays to $D^+\pi^-$, $D^0 \pi^+$ and $D^{*+}\pi^-$
  final states in pp collision

abstract:
  A study of $D^+\pi^-$, $D^0 \pi^+$ and $D^{*+}\pi^-$ final states is
performed using pp collision data, corresponding to an integrated luminosity of
1.0 $fb^{-1}$, collected at a centre-of-mass energy of 7 TeV with the LHCb
detector. The $D_1(2420)^0$ resonance is observed in the $D^{*+}\pi^-$ final
state and the $D^*_2(2460)$ resonance is observed in the $D^+\pi^-$, $D^0
\pi^+$ and $D^{*+}\pi^-$ final states. For both resonances, their properties
and spin-parity assignments are obtained. In addition, two natural parity and
two unnatural parity resonances are observed in the mass region between 2500
and 2800 MeV. Further structures in the region around 3000 MeV are observed in
all the $D^{*+}\pi^-$, $D^+\pi^-$ and $D^0 \pi^+$ final states.


title: Dielectric Coatings for IACT Mirrors

abstract:
  Imaging Atmospheric Cherenkov Telescopes for very-high energy gamma-ray
astronomy need mirror with high reflectance roughly in the wavelength between
300 and 550 nm. The current standard reflective layer of such mirrors is
aluminum. Being permanently exposed to the environment they show a constant
degradation over the years. New and improved dielectric coatings have been
developed to enhance their resistance to environmental impact and to extend
their possible lifetime. In addition, these customized coatings have an
increased reflectance of over 95% and are designed to significantly lower the
night-sky background contribution. The development of such coatings for mirrors
with areas up to 2 m2 and low application temperatures to suite the composite
materials used for the new mirror susbtrates of the Cherenkov Telescope Array
(CTA) and the results of extensive durability tests are presented.


title: Dressing the Electron Star in a Holographic Superconductor

abstract:
  We construct new asymptotically AdS_4 solutions dual to 2+1 CFTs at finite
density and zero temperature by combining the ingredients of the electron star
and the holographic superconductor. The solutions, which we call "compact
electron stars", contain both a fermionic fluid and charged scalar hair in the
bulk. We show that the new solutions are thermodynamically favoured in the
region of parameter space where they exist. Along the boundary of this region,
we find evidence for a continuous phase transition between the holographic
superconductor and the compact star solution.


title: Electron-Phonon Coupling on the Surface of Topological Insulators

abstract:
  Topological insulators (TIs) are materials that have a bulk electronic band
gap like an ordinary insulator but have protected conducting states on their
surface. One of the most interesting properties of TIs is their spin helicity,
whereby the spin is locked normal to the wave vector of the surface electronic
state. The topological surface states should be very stable in TIs, since these
spin-textured surface states are robust against spin-independent
backscattering. Scattering from defects and other lattice imperfections is
possible provided the spin is not completely flipped. However, the quality of
TI crystals can be controlled by careful growth, whereas phonons will exist in
even the most perfect crystals. Consequently, electron-phonon coupling (EPC)
should be the dominant scattering mechanism for surface electronic states at
finite temperatures. Hence, the study of EPC in TIs is of exceptional
importance in assessing any potential applications. In this article both
experimental and theoretical studies of the EPC on the surface of TIs are
reviewed, with the contents mainly focused on the typical strong three
dimensional TIs, such as Bi2Se3 and Bi2Te3.


title:
Search for di-muon decays of a light scalar Higgs boson in radiative
  Y(1S) decays

abstract:
  We search for di-muon decays of a low-mass Higgs boson ($A^0$) in the fully
reconstructed decay chain of $\Upsilon(2S,3S) \to \pipi\Upsilon(1S)$,
$\Upsilon(1S) \to \g A^0$, $A^0 \to \mumu$. The $A^0$ is predicted by several
extensions of the Standard Model (SM), including the Next-to-Minimal
Supersymmetric Standard Model (NMSSM). NMSSM introduces a \CP-odd light Higgs
boson whose mass could be less than 10 \gevcc. The data samples used in this
analysis contain $92.8 \times 10^6$ $\Upsilon(2S)$ and $116.8 \times 10^6$
$\Upsilon(3S)$ events collected by the \babar\ detector. The $\Upsilon(1S)$
sample is selected by tagging the pion pair in the $\Upsilon(2S, 3S) \to
\pi^+\pi^-\Upsilon(1S)$ transitions. We find no evidence for $A^0$ production
and set 90% confidence level (C.L.) upper limits on the product branching
fraction $\mathcal{B}(\Upsilon(1S) \to \g A^0) \times \mathcal{B}(A^0 \to
\mumu)$ in the range of $(0.28 - 9.7)\times 10^{-6}$ for $0.212 \le m_{A^0} \le
9.20$ \gevcc. We also combine our results with previous \babar\ results of
$\Upsilon(2S,3S) \to \g A^0$, $A^0 \to \mumu$ to set limits on the effective
coupling ($f_{\Upsilon}$) of the \b-quark to the $A^0$, $f_{\Upsilon}^2 \times
\mathcal{B}(A^0 \to \mumu)$, at the level of $(0.29 - 40)\times 10^{-6}$ for
$0.212 \le m_{A^0} \le 9.2$ GeV/$c^2$.


title: Detection of the buckminsterfullerene cation (C60+) in space

abstract:
  In the early 90s, C60+ was proposed as the carrier of two diffuse
interstellar bands (DIBs) at 957.7 and 963.2 nm, but a firm identification
still awaits gas-phase spectroscopic data. Neutral C60, on the other hand, was
recently detected through its infrared emission bands in the interstellar
medium and evolved stars. In this contribution, we present the detection of
C60+ through its infrared vibrational bands in the NGC 7023 nebula, based on
spectroscopic observations with the Spitzer space telescope, quantum chemistry
calculation, and laboratory data from the literature. This detection supports
the idea that C60+ could be a DIB carrier, and provides robust evidence that
fullerenes exist in the gas-phase in the interstellar medium. Modeling efforts
to design specific observations, combined with new gas-phase data, will be
essential to confirm this proposal. A definitive attribution of the 957.7 and
963.2 nm DIBs to C60+ would represent a significant step forward in the field.


title: CO observation of the Galactic bubble N4

abstract:
  We presented a study on the Galactic bubble N4 using the 13.7 m millimeter
telescope of Purple Mountain Observatory at the Qinghai Station. N4 is one of
the science demonstration regions for the Milky Way Imaging Scroll Painting
(WMISP). Simultaneous observations of $^{12}$CO (J = 1$-$0), $^{13}$CO (J =
1$-$0) and C$^{18}$O (J = 1$-$0) line emission towards N4 were carried out. We
analyzed the spectral profile and the distribution of the molecular gas.
Morphologically, the CO emissions correlate well with Spitzer IRAC 8.0 $\mu$m
emission. The channel map and velocity-position diagram shows that N4 is more
likely an inclined expanding ring than a spherical bubble. We calculated the
physical parameters of N4 including the mass, size, column density and optical
depth. Some massive star candidates were discovered in the region of N4 using
(J, J$-$H) color-magnitude diagram. We found an energy source candidate for the
expansion of N4, a massive star with a mass of ${\sim} 15\,M_{\odot}$ and an
age of $\sim$ 1 Myr. There exists infall motion signature in N4, which can be a
good candidate of infall area. Combined mm and infrared data, we think there
may exists triggered star formation in N4.


title: Mirror Development for the Cherenkov Telescope Array

abstract:
  The Cherenkov Telescope Array (CTA) is a planned observatory for very-high
energy gamma-ray astronomy. It will consist of several tens of telescopes of
different sizes, with a total mirror area of up to 10,000 square meters. Most
mirrors of current installations are either polished glass mirrors or
diamond-turned aluminium mirrors, both labour intensive technologies. For CTA,
several new technologies for a fast and cost-efficient production of
light-weight and reliable mirror substrates have been developed and industrial
pre-production has started for most of them. In addition, new or improved
aluminium-based and dielectric surface coatings have been developed to increase
the reflectance over the lifetime of the mirrors compared to those of current
Cherenkov telescope instruments.


title: From Bandits to Experts: A Tale of Domination and Independence

abstract:
  We consider the partial observability model for multi-armed bandits,
introduced by Mannor and Shamir. Our main result is a characterization of
regret in the directed observability model in terms of the dominating and
independence numbers of the observability graph. We also show that in the
undirected case, the learner can achieve optimal regret without even accessing
the observability graph before selecting an action. Both results are shown
using variants of the Exp3 algorithm operating on the observability graph in a
time-efficient manner.


title: The Cherenkov Telescope Array Large Size Telescope

abstract:
  The two arrays of the Very High Energy gamma-ray observatory Cherenkov
Telescope Array (CTA) will include four Large Size Telescopes (LSTs) each with
a 23 m diameter dish and 28 m focal distance. These telescopes will enable CTA
to achieve a low-energy threshold of 20 GeV, which is critical for important
studies in astrophysics, astroparticle physics and cosmology. This work
presents the key specifications and performance of the current LST design in
the light of the CTA scientific objectives.


title: Spatial Fluid Limits for Stochastic Mobile Networks

abstract:
  We consider Markov models of large-scale networks where nodes are
characterized by their local behavior and by a mobility model over a
two-dimensional lattice. By assuming random walk, we prove convergence to a
system of partial differential equations (PDEs) whose size depends neither on
the lattice size nor on the population of nodes. This provides a macroscopic
view of the model which approximates discrete stochastic movements with
continuous deterministic diffusions. We illustrate the practical applicability
of this result by modeling a network of mobile nodes with on/off behavior
performing file transfers with connectivity to 802.11 access points. By means
of an empirical validation against discrete-event simulation we show high
quality of the PDE approximation even for low populations and coarse lattices.
In addition, we confirm the computational advantage in using the PDE limit over
a traditional ordinary differential equation limit where the lattice is modeled
discretely, yielding speed-ups of up to two orders of magnitude.


title:
Benchmarking mixed-mode PETSc performance on high-performance
  architectures

abstract:
  The trend towards highly parallel multi-processing is ubiquitous in all
modern computer architectures, ranging from handheld devices to large-scale HPC
systems; yet many applications are struggling to fully utilise the multiple
levels of parallelism exposed in modern high-performance platforms. In order to
realise the full potential of recent hardware advances, a mixed-mode between
shared-memory programming techniques and inter-node message passing can be
adopted which provides high-levels of parallelism with minimal overheads. For
scientific applications this entails that not only the simulation code itself,
but the whole software stack needs to evolve. In this paper, we evaluate the
mixed-mode performance of PETSc, a widely used scientific library for the
scalable solution of partial differential equations. We describe the addition
of OpenMP threaded functionality to the library, focusing on sparse
matrix-vector multiplication. We highlight key challenges in achieving good
parallel performance, such as explicit communication overlap using task-based
parallelism, and show how to further improve performance by explicitly load
balancing threads within MPI processes. Using a set of matrices extracted from
Fluidity, a CFD application code which uses the library as its linear solver
engine, we then benchmark the parallel performance of mixed-mode PETSc across
multiple nodes on several modern HPC architectures. We evaluate the parallel
scalability on Uniform Memory Access (UMA) systems, such as the Fujitsu
PRIMEHPC FX10 and IBM BlueGene/Q, as well as a Non-Uniform Memory Access (NUMA)
Cray XE6 platform. A detailed comparison is performed which highlights the
characteristics of each particular architecture, before demonstrating efficient
strong scalability of sparse matrix-vector multiplication with significant
speedups over the pure-MPI mode.


title:
Measurement of the top quark charge in pp collisions at sqrt(s) = 7 TeV
  with the ATLAS detector

abstract:
  A measurement of the top quark electric charge is carried out in the ATLAS
experiment at the Large Hadron Collider using 2.05 fb-1 of data at a
centre-of-mass energy of 7 TeV. In units of the elementary electric charge, the
top quark charge is determined to be 0.64 +- 0.02 (stat.) +- 0.08 (syst.) from
the charges of the top quark decay products in single lepton ttbar candidate
events. This excludes models that propose a heavy quark of electric charge
--4/3, instead of the Standard Model top quark, with a significance of more
than 8 sigma.


title:
Efficient algorithms for discrete Gabor transforms on a nonseparable
  lattice

abstract:
  The Discrete Gabor Transform (DGT) is the most commonly used transform for
signal analysis and synthesis using a linear frequency scale. It turns out that
the involved operators are rich in structure if one samples the discrete phase
space on a subgroup. Most of the literature focuses on separable subgroups, in
this paper we will survey existing methods for a generalization to arbitrary
groups, as well as present an improvement on existing methods. Comparisons are
made with respect to the computational complexity, and the running time of
optimized implementations in the C programming language. The new algorithms
have the lowest known computational complexity for nonseparable lattices and
the implementations are freely available for download. By summarizing general
background information on the state of the art, this article can also be seen
as a research survey, sharing with the readers experience in the numerical work
in Gabor analysis.


title: Coordinate changed random fields on manifolds

abstract:
  We introduce a class of time dependent random fields on compact Riemannian
monifolds. These are represented by time-changed Brownian motions. These
processes are time-changed diffusion, or the stochastic solution to the
equation involving the Laplace-Beltrami operator and a time-fractional
derivative of order $\beta\in (0,1)$. The time dependent random fields we
present in this work can therefore be realized through composition and can be
viewed as random fields on randomly varying manifolds.


title: Gaussian entanglement induced by an extended thermal environment

abstract:
  We study stationary entanglement among three harmonic oscillators which are
dipole coupled to a one-dimensional or a three-dimensional bosonic environment.
The analysis of the open-system dynamics is performed with generalized quantum
Langevin equations which we solve exactly in Fourier representation. The focus
lies on Gaussian bipartite and tripartite entanglement induced by the highly
non-Markovian interaction mediated by the environment. This environment-induced
interaction represents an effective many-parties interaction with a spatial
long-range feature: a main finding is that the presence of a passive oscillator
is detrimental for the stationary two-mode entanglement. Furthermore, our
results strongly indicate that the environment-induced entanglement mechanism
corresponds to uncontrolled feedback which is predominantly coherent at low
temperatures and for moderate oscillator-environment coupling as compared to
the oscillator frequency.


title: Bose-Fermi competition in holographic metals

abstract:
  We study the holographic dual of a finite density system with both bosonic
and fermionic degrees of freedom. There is no evidence for a universal
bose-dominated ground state. Instead, depending on the relative conformal
weights the preferred groundstate is either pure AdS-Reissner-Nordstrom, a
holographic superconductor, an electron star, or a novel mixed state that is
best characterized as a hairy electron star.


title: Finite group actions on Lagrangian Floer theory

abstract:
  We construct finite group actions on Lagrangian Floer theory when symplectic
manifolds have finite group actions and Lagrangian submanifolds have induced
group actions. We first define finite group actions on Novikov-Morse theory. We
introduce the notion of a {\em spin profile} as an obstruction class of
extending the group action on Lagrangian submanifold to the one on its spin
structure, which is a group cohomology class in $H^2(G;\Z/2)$. For a class of
Lagrangian submanifolds which have the same spin profiles, we define a finite
group action on their Fukaya category. In consequence, we obtain the
$s$-equivariant Fukaya category as well as the $s$-orbifolded Fukaya category
for each group cohomology class $s$. We also develop a version with
$G$-equivariant bundles on Lagrangian submanifolds, and explain how character
group of $G$ acts on the theory.
  As an application, we define an orbifolded Fukaya-Seidel category of a
$G$-invariant Lefschetz fibration, and also discuss homological mirror symmetry
conjectures with group actions.


title:
Analysis of the Taylor dissipation surrogate in forced isotropic
  turbulence

abstract:
  From the energy balance in wavenumber space expressed by the Lin equation, we
derive a new form for the local Karman-Howarth equation for forced isotropic
turbulence in real space. This equation is then cast into a dimensionless form,
from which a combined analytical and numerical study leads us to deduce a new
model for the scale-independent nondimensional dissipation rate $\Ceps$, which
takes the form $\Ceps = \Cinf + C_L/R_L$, where the asymptotic value $\Cinf$
can be evaluated from the third-order structure function. This is found to fit
the numerical data with $\Cinf = 0.47 \pm 0.01$ and $C_L= 18.5 \pm 1.3$. By
considering $\Ceps - \Cinf$ on logarithmic scales, we show that $R_L^{-1}$ is
indeed the correct Reynolds number behaviour. The model is compared to previous
attempts in the literature, with encouraging agreement. The effects of the
scale-dependence of the inertial and viscous terms due to finite forcing are
then considered and shown to compensate one another, such that the model
equation is applicable for systems subject to finite forcing. In addition, we
also show that, contrary to the case of freely decaying turbulence, the
characteristic decline in $\Ceps$ with increasing Reynolds number is due to the
\emph{increase} in the surrogate expression $U^3/L$; the dissipation rate being
maintained constant as a consequence of the fixed rate of forcing. A long-time
non-turbulent stable state is found to exist for low Reynolds number numerical
simulations which use negative damping as a means of energy injection.


title: A new method of identifying self-similarity in isotropic turbulence

abstract:
  In order to analyse results for structure functions, $S_n(r)$, we propose
plotting the ratio $|S_n(r)/S_3(r)|$ against the separation $r$. This method
differs from the extended self-similarity (ESS) technique, which plots $S_n(r)$
against $S_3(r)$, where $S_3(r) \sim r$. Using this method in conjunction with
pseudospectral evaluation of structure functions, for the particular case of
$S_2(r)$ we obtain the new result that the exponent $\zeta_2$ decreases as the
Taylor-Reynolds number increases, with $\zeta_2 \to 0.67 \pm 0.02$ as
$R_\lambda \to \infty$. This supports the idea of finite-viscosity corrections
to the K41 prediction for $S_2$, and is the opposite of the result obtained by
ESS.


title: A gas-rich AGN near the centre of a galaxy cluster at z ~ 1.4

abstract:
  The formation of the first virialized structures in overdensities dates back
to ~9 Gyr ago, i.e. in the redshift range z ~ 1.4 - 1.6. Some models of
structure formation predict that the star formation activity in clusters was
high at that epoch, implying large reservoirs of cold molecular gas. Aiming at
finding a trace of this expected high molecular gas content in primeval
clusters, we searched for the 12CO(2-1) line emission in the most luminous
active galactic nucleus (AGN) of the cluster around the radio galaxy 7C
1756+6520 at z ~ 1.4, one of the farthest spectroscopic confirmed clusters.
This AGN, called AGN.1317, is located in the neighbourhood of the central radio
galaxy at a projected distance of ~780 kpc. The IRAM Plateau de Bure
Interferometer was used to investigate the molecular gas quantity in AGN.1317,
observing the 12CO(2-1) emission line. We detect CO emission in an AGN
belonging to a galaxy cluster at z ~ 1.4. We measured a molecular gas mass of
1.1 x 10^10 Msun, comparable to that found in submillimeter galaxies. In
optical images, AGN.1317 does not seem to be part of a galaxy interaction or
merger.We also derived the nearly instantaneous star formation rate (SFR) from
Halpha flux obtaining a SFR ~65 Msun/yr. This suggests that AGN.1317 is
actively forming stars and will exhaust its reservoir of cold gas in ~0.2-1.0
Gyr.


title:
X-ray diffraction from isolated and strongly aligned gas-phase molecules
  with a free-electron laser

abstract:
  We report experimental results on x-ray diffraction of quantum-state-selected
and strongly aligned ensembles of the prototypical asymmetric rotor molecule
2,5-diiodobenzonitrile using the Linac Coherent Light Source. The experiments
demonstrate first steps toward a new approach to diffractive imaging of
distinct structures of individual, isolated gas-phase molecules. We confirm
several key ingredients of single molecule diffraction experiments: the
abilities to detect and count individual scattered x-ray photons in single shot
diffraction data, to deliver state-selected, e. g., structural-isomer-selected,
ensembles of molecules to the x-ray interaction volume, and to strongly align
the scattering molecules. Our approach, using ultrashort x-ray pulses, is
suitable to study ultrafast dynamics of isolated molecules.


title:
Tests of model predictions for the response of stellar spectra and
  absorption line indices to element abundance variations

abstract:
  To analyse stellar populations in galaxies a widely used method is to apply
theoretically derived responses of stellar spectra and line indices to element
abundance variations, hereafter referred to as response functions. These are
applied in a differential way, to base models, in order to generate spectra or
indices with different abundance patterns. In this paper sets of such response
functions for three different stellar evolutionary stages are tested with new
empirical [Mg/Fe] abundance data for the MILES stellar spectral library. Recent
theoretical models and observations are used to investigate the effects of
[Fe/H], [Mg/H] and overall [Z/H] on spectra, via ratios of spectra for similar
stars. Global effects of changes in abundance patterns are investigated
empirically through direct comparisons of similar stars from the MILES library,
highlighting the impact of abundance effects in the blue part of the spectrum,
particularly for lower temperature stars. It is found that the relative
behaviour of iron sensitive line indices are generally well predicted by
response functions, whereas Balmer line indices are not. Other indices tend to
show large scatter about the predicted mean relations. Implications for element
abundance and age studies in stellar populations are discussed and ways forward
are suggested to improve the match with behaviours of spectra and line strength
indices observed in real stars.


title:
RSP-Based Analysis for Sparsest and Least $\ell_1$-Norm Solutions to
  Underdetermined Linear Systems

abstract:
  Recently, the worse-case analysis, probabilistic analysis and empirical
justification have been employed to address the fundamental question: When does
$\ell_1$-minimization find the sparsest solution to an underdetermined linear
system? In this paper, a deterministic analysis, rooted in the classic linear
programming theory, is carried out to further address this question. We first
identify a necessary and sufficient condition for the uniqueness of least
$\ell_1$-norm solutions to linear systems. From this condition, we deduce that
a sparsest solution coincides with the unique least $\ell_1$-norm solution to a
linear system if and only if the so-called \emph{range space property} (RSP)
holds at this solution. This yields a broad understanding of the relationship
between $\ell_0$- and $\ell_1$-minimization problems. Our analysis indicates
that the RSP truly lies at the heart of the relationship between these two
problems. Through RSP-based analysis, several important questions in this field
can be largely addressed. For instance, how to efficiently interpret the gap
between the current theory and the actual numerical performance of
$\ell_1$-minimization by a deterministic analysis, and if a linear system has
multiple sparsest solutions, when does $\ell_1$-minimization guarantee to find
one of them? Moreover, new matrix properties (such as the \emph{RSP of order
$K$} and the \emph{Weak-RSP of order $K$}) are introduced in this paper, and a
new theory for sparse signal recovery based on the RSP of order $K$ is
established.


title:
Pointing Calibration for the Cherenkov Telescope Array Medium Size
  Telescope Prototype

abstract:
  Pointing calibration is an offline correction applied in order to obtain the
true pointing direction of a telescope. The Cherenkov Telescope Array (CTA)
aims to have the precision to determine the position of point-like as well as
slightly extended sources, with the goal of systematic errors less than 7 arc
seconds in space angle. This poster describes the pointing calibration concept
being developed for the CTA Medium Size Telescope (MST) prototype at
Berlin-Adlershof, showing test results and preliminary measurements. The MST
pointing calibration method uses two CCD cameras, mounted on the telescope
dish, to determine the true pointing of the telescope. The "Lid CCD" is aligned
to the optical axis of the telescope, calibrated with LEDs on the dummy
gamma-camera lid; the "Sky CCD" is pre-aligned to the Lid CCD and the
transformation between the Sky and Lid CCD camera fields of view is precisely
modelled with images from special pointing runs which are also used to
determine the pointing model. During source tracking, the CCD cameras record
images which are analysed offline using software tools including Astrometry.net
to determine the true pointing coordinates.


title: Smart Streaming for Online Video Services

abstract:
  Bandwidth consumption is a significant concern for online video service
providers. Practical video streaming systems usually use some form of HTTP
streaming (progressive download) to let users download the video at a faster
rate than the video bitrate. Since users may quit before viewing the complete
video, however, much of the downloaded video will be "wasted". To the extent
that users' departure behavior can be predicted, we develop smart streaming
that can be used to improve user QoE with limited server bandwidth or save
bandwidth cost with unlimited server bandwidth. Through measurement, we extract
certain user behavior properties for implementing such smart streaming, and
demonstrate its advantage using prototype implementation as well as
simulations.


title: How neutron stars constrain the nuclear equation of state

abstract:
  Recent neutron star observations set new constraints for the equation of
state of baryonic matter. A chiral effective field theory approach is used for
the description of neutron-dominated nuclear matter present in the outer core
of neutron stars. Possible hybrid stars with quark matter in the inner core are
discussed using a three-flavor Nambu--Jona-Lasinio model.


title:
Simply conceiving the Arrhenius law and absolute kinetic constants using
  the geometric distribution

abstract:
  Although first-order rate constants are basic ingredients of physical
chemistry, biochemistry and systems modeling, their innermost nature is derived
from complex physical chemistry mechanisms. The present study suggests that
equivalent conclusions can be more straightly obtained from simple statistics.
The different facets of kinetic constants are first classified and clarified
with respect to time and energy and the equivalences between traditional flux
rate and modern probabilistic modeling are summarized. Then, a naive but
rigorous approach is proposed to concretely perceive how the Arrhenius law
naturally emerges from the geometric distribution. It appears that (1) the
distribution in time of chemical events as well as (2) their mean frequency,
are both dictated by randomness only and as such, are accurately described by
time-based and spatial exponential processes respectively.


title:
The (non-)variability of magnetic chemically peculiar candidates in the
  Large Magellanic Cloud

abstract:
  The galactic magnetic chemically peculiar (mCP) stars of the upper main
sequence are well known as periodic spectral and light variables. The observed
variability is obviously caused by the uneven distribution of overabundant
chemical elements on the surfaces of rigidly rotating stars. The mechanism
causing the clustering of some chemical elements into disparate structures on
mCP stars has not been fully understood up to now. The observations of light
changes of mCP candidates recently revealed in the nearby Large Magellanic
Cloud (LMC) should provide us with information about their rotational periods
and about the distribution of optically active elements on mCP stars born in
other galaxies. We queried for photometry at the Optical Gravitational Lensing
Experiment (OGLE)-III survey of published mCP candidates selected because of
the presence of the characteristic 5200A flux depression. In total, the
intersection of both sources resulted in twelve stars. We performed our own and
standard periodogram time series analyses of all available data. The final
results are, amongst others, the frequency of the maximum peak and the
bootstrap probability of its reality. We detected that only two mCP candidates,
190.1 1581 and 190.1 15527, may show some weak rotationally modulated light
variations with periods of 1.23 and 0.49 days; however, the 49% and 32%
probabilities of their reality are not very satisfying. The variability of the
other 10 mCP candidates is too low to be detectable by their V and I OGLE
photometry. The relatively low amplitude variability of the studied LMC mCP
candidates sample can be explained by the absence of photometric spots of
overabundant optically active chemical elements. The unexpected LMC mCPs
behaviour is probably caused by different conditions during the star formation
in the LMC and the Galaxy.


title: Pushdown Systems for Monotone Frameworks

abstract:
  Monotone frameworks is one of the most successful frameworks for
intraprocedural data flow analysis extending the traditional class of bitvector
frameworks (like live variables and available expressions). Weighted pushdown
systems is similarly one of the most general frameworks for interprocedural
analysis of programs. However, it makes use of idempotent semirings to
represent the sets of properties and unfortunately they do not admit analyses
whose transfer functions are not strict (e.g., classical bitvector frameworks).
This motivates the development of algorithms for backward and forward
reachability of pushdown systems using sets of properties forming so-called
flow algebras that weaken some of the assumptions of idempotent semirings. In
particular they do admit the bitvector frameworks, monotone frameworks, as well
as idempotent semirings. We show that the algorithms are sound under mild
assumptions on the flow algebras, mainly that the set of properties constitutes
a join semi-lattice, and complete provided that the transfer functions are
suitably distributive (but not necessarily strict).


title:
Impact of the Cherenkov Telescope Array (CTA) altitude on Dark Matter
  searches in the Milky Way Halo

abstract:
  Observations of dwarf galaxies and of the Milky Way halo with current
ground-based Cherenkov telescopes have resulted in interesting limits on the
cross-section for dark matter (DM) self- annihilation for WIMP masses above
some 100 GeV. The future Cherenkov Telescope Array (CTA) is expected to further
explore the parameter space of dark matter candidates that are predicted in
extensions of the standard model of particle physics. Due to its low energy
threshold (of order of few tens of GeV) and high sensitivity, CTA will also
probe lower WIMP masses than current experiments, but the actual performance in
this regime will be influenced by the altitude of the observatory above sea
level. Using the response of possible CTA candidate arrays to simulated photons
and hadrons, we estimate how searches for a WIMP annihilation signal from the
Milky Way halo will be influenced by altitude of different possible CTA sites.


title:
A Divergence-Free Method to Extract Observables from Meson Correlation
  Functions

abstract:
  Correlation functions provide information on the properties of mesons in
vacuum and of hot nuclear matter. In this Letter, we present a new method to
derive a well-defined spectral representation for correlation functions.
Combining this method with the quark gap equation and the inhomogeneous
Bethe-Salpeter equation in the rainbow-ladder approximation, we calculate
in-vacuum masses of light mesons and the electrical conductivity of the
quark-gluon plasma. The analysis can be extended to other observables of
strong-interaction systems.


title: Plasmonic Antennas Hybridized with Dielectric Waveguides

abstract:
  For the purpose of using plasmonics in an integrated scheme where single
emitters can be probed efficiently, we experimentally and theoretically study
the scattering properties of single nano-rod gold antennas as well as antenna
arrays placed on one-dimensional dielectric silicon nitride waveguides. Using
real space and Fourier microscopy correlated with waveguide transmission
measurements, we quantify the spectral properties, absolute strength and
directivity of scattering. The scattering processes can be well understood in
the framework of the physics of dipolar objects placed on a planar layered
environment with a waveguiding layer. We use the single plasmonic structures on
top of the waveguide as dipolar building blocks for new types of antennas where
the waveguide enhances the coupling between antenna elements. We report on
waveguide hybridized Yagi-Uda antennas which show directionality in
out-coupling of guided modes as well as directionality for in-coupling into the
waveguide of localized excitations positioned at the feed element. These
measurements together with simulations demonstrate that this system is ideal as
a platform for plasmon quantum optics schemes as well as for fluorescence
lab-on-chip applications.


title: BSM Higgs results from ATLAS and CMS

abstract:
  Searches for Higgs bosons in different extensions of the Standard Model (SM)
are presented. These include the Minimal Supersymmetric extension of the SM
(MSSM), the next-to-MSSM (NMSSM), models with additional scalar singlets,
doublets, or triplets, and generic searches for models with couplings modified
with respect to the SM or for non-SM Higgs boson decay channels. Results are
based on data collected by the ATLAS and CMS experiments in 2011 and 2012 at
the LHC. No excess is found in any of the searches and thus the resulting
exclusion limits are given.


title: A 325-MHz GMRT survey of the Herschel-ATLAS/GAMA fields

abstract:
  We describe a 325-MHz survey, undertaken with the Giant Metrewave Radio
Telescope (GMRT), which covers a large part of the three equatorial fields at
9, 12 and 14.5 h of right ascension from the Herschel-Astrophysical Terahertz
Large Area Survey (H-ATLAS) in the area also covered by the Galaxy And Mass
Assembly survey (GAMA). The full dataset, after some observed pointings were
removed during the data reduction process, comprises 212 GMRT pointings
covering ~90 deg^2 of sky. We have imaged and catalogued the data using a
pipeline that automates the process of flagging, calibration, self-calibration
and source detection for each of the survey pointings. The resulting images
have resolutions of between 14 and 24 arcsec and minimum rms noise (away from
bright sources) of ~1 mJy/beam, and the catalogue contains 5263 sources
brighter than 5 sigma. We investigate the spectral indices of GMRT sources
which are also detected at 1.4 GHz and find them to agree broadly with
previously published results; there is no evidence for any flattening of the
radio spectral index below S_1.4=10 mJy. This work adds to the large amount of
available optical and infrared data in the H-ATLAS equatorial fields and will
facilitate further study of the low-frequency radio properties of star
formation and AGN activity in galaxies out to z~1.


title:
Utility indifference valuation for non-smooth payoffs with an
  application to power derivatives

abstract:
  We consider the problem of exponential utility indifference valuation under
the simplified framework where traded and nontraded assets are uncorrelated but
where the claim to be priced possibly depends on both. Traded asset prices
follow a multivariate Black and Scholes model, while nontraded asset prices
evolve as generalized Ornstein-Uhlenbeck processes. We provide a BSDE
characterization of the utility indifference price (UIP) for a large class of
non-smooth, possibly unbounded, payoffs depending simultaneously on both
classes of assets. Focusing then on European claims and using the Gaussian
structure of the model allows us to employ some BSDE techniques (in particular,
a Malliavin-type representation theorem due to Ma (2002)) to prove the
regularity of Z and to characterize the UIP for possibly discontinuous European
payoffs as a viscosity solution of a suitable PDE with continuous space
derivatives. The optimal hedging strategy is also identified essentially as the
delta hedging strategy corresponding to the UIP. Since there are no closed-form
formulas in general, we also obtain asymptotic expansions for prices and
hedging strategies when the risk aversion parameter is small. Finally, our
results are applied to pricing and hedging power derivatives in various
structural models for energy markets.


title:
Processing stationary noise: model and parameter selection in
  variational methods

abstract:
  Additive or multiplicative stationary noise recently became an important
issue in applied fields such as microscopy or satellite imaging. Relatively few
works address the design of dedicated denoising methods compared to the usual
white noise setting. We recently proposed a variational algorithm to tackle
this issue. In this paper, we analyze this problem from a statistical point of
view and provide deterministic properties of the solutions of the associated
variational problems. In the first part of this work, we demonstrate that in
many practical problems, the noise can be assimilated to a colored Gaussian
noise. We provide a quantitative measure of the distance between a stationary
process and the corresponding Gaussian process. In the second part, we focus on
the Gaussian setting and analyze denoising methods which consist of minimizing
the sum of a total variation term and an $l^2$ data fidelity term. While the
constrained formulation of this problem allows to easily tune the parameters,
the Lagrangian formulation can be solved more efficiently since the problem is
strongly convex. Our second contribution consists in providing analytical
values of the regularization parameter in order to approximately satisfy
Morozov's discrepancy principle.


title:
Gauge Coupling Unification in E6 F-Theory GUTs with Matter and Bulk
  Exotics from Flux Breaking

abstract:
  We consider gauge coupling unification in E6 F-Theory Grand Unified Theories
(GUTs) where E6 is broken to the Standard Model (SM) gauge group using fluxes.
In such models there are two types of exotics that can affect gauge coupling
unification, namely matter exotics from the matter curves in the 27 dimensional
representation of E6 and the bulk exotics from the adjoint 78 dimensional
representation of E6. We explore the conditions required for either the
complete or partial removal of bulk exotics from the low energy spectrum. In
the latter case we shall show that (miraculously) gauge coupling unification
may be possible even if there are bulk exotics at the TeV scale. Indeed in some
cases it is necessary for bulk exotics to survive to the TeV scale in order to
cancel the effects coming from other TeV scale matter exotics which would by
themselves spoil gauge coupling unification. The combination of matter and bulk
exotics in these cases can lead to precise gauge coupling unification which
would not be possible with either type of exotics considered by themselves. The
combination of matter and bulk exotics at the TeV scale represents a unique and
striking signature of E6 F-theory GUTs that can be tested at the LHC.


title:
Devasthal Fast Optical Telescope observations of Wolf-Rayet dwarf galaxy
  Mrk 996

abstract:
  The Devasthal Fast Optical Telescope (DFOT) is a 1.3 meter aperture optical
telescope, recently installed at Devasthal, Nainital. We present here the first
results using an \Ha filter with this telescope on a Wolf-Rayet dwarf galaxy
Mrk 996. The instrumental response and the \Ha sensitivity obtained with the
telescope are $(3.3 \pm 0.3)\times 10^{-15} (erg s^{-1} cm^{-2})/(counts
s^{-1})$ and $7.5\times10^{-17} erg s^{-1} cm^{-2} arcsec^{-2}$ respectively.
The \Ha flux and the equivalent width for Mrk~996 are estimated as $(132 \pm
37)\times 10^{-14} erg s^{-1} cm^{-2}$ and $\sim$96 $\mathring{A}$
respectively. The star formation rate is estimated as $0.4\pm0.1
M_\odot$yr$^{-1}$. Mrk~996 deviates from the radio-FIR correlation known for
normal star forming galaxies with a deficiency in its radio continuum. The
ionized gas as traced by \Ha emission is found in a disk shape which is
misaligned with respect to the old stellar disk. This misalignment is
indicative of a recent tidal interaction in the galaxy. We believe that
galaxy-galaxy tidal interaction is the main cause of the WR phase in Mrk~996.


title: Quantum and thermal fluctuations in bosonic Josephson junctions

abstract:
  We use the Bose-Hubbard Hamiltonian to study quantum fluctuations in
canonical equilibrium ensembles of bosonic Josephson junctions at relatively
high temperatures, comparing the results for finite particle numbers to the
classical limit that is attained as $N$ approaches infinity. We consider both
attractive and repulsive atom-atom interactions, with especial focus on the
behavior near the T=0 quantum phase transition that occurs, for large enough
$N$, when attractive interactions surpass a critical level. Differences between
Bose-Hubbard results for small $N$ and those of the classical limit are quite
small even when $N \sim 100$, with deviations from the limit diminishing as
1/N.


title: Magnetization and susceptibility of polydisperse ferrofluids

abstract:
  On the basis of the mean spherical approximation of multicomponent dipolar
hard sphere mixtures an analytical expression is proposed for the magnetic
field dependence of the magnetization of size polydisperse ferrofluids. The
polydispersity of the particle diameter is described by the gamma distribution
function. Canonical ensemble Monte Carlo simulations have been performed in
order to test these theoretical results for the initial susceptibility and the
magnetization. The results for the magnetic properties of the polydisperse
systems turn out to be in quantitative agreement with our present simulation
data. In addition, we find good agreement between our theory and experimental
data for magnetite-based ferrofluids.


title:
Anisotropic Quantum Spin Hall Effect, Spin-Orbital Textures and Mott
  Transition

abstract:
  We investigate the interplay between topological effects and Mott physics in
two dimensions on a graphene-like lattice, via a tight-binding model containing
an anisotropic spin-orbit coupling on the next-nearest-neighbour links and the
Hubbard interaction. We thoroughly analyze the resulting phases, namely a
topological band insulator phase or anisotropic quantum Spin Hall phase until
moderate interactions, a N\'eel and Spiral phase at large interactions in the
Mott regime, as well as the formation of a spin-orbital texture in the bulk at
the Mott transition. The emergent magnetic orders at large interactions are
analyzed through a spin wave analysis and mathematical arguments. At weak
interactions, by analogy with the Kane-Mele model, the system is described
through a Z_2 topological invariant. In addition, we describe how the
anisotropic spin-orbit coupling already produces an exotic spin texture at the
edges. The physics at the Mott transition is described in terms of a U(1) slave
rotor theory. Taking into account gauge fluctuations around the mean-field
saddle point solution, we show how the spin texture now proliferates into the
bulk above the Mott critical point. The latter emerges from the response of the
spinons under the insertion of monopoles and this becomes more pronounced as
the spin-orbit coupling becomes prevalent. We discuss implications of our
predictions for thin films of the iridate compound Na2IrO3 and also
graphene-like systems.


title: PPN expansion and FRW scalar perturbations in n-DBI gravity

abstract:
  n-DBI gravity explicitly breaks Lorentz invariance by the introduction of a
unit time-like vector field, thereby giving rise to an extra (scalar) degree of
freedom. We look for observational consequences of this mode in two setups.
Firstly, we compute the parametrized post-Newtonian (PPN) expansion of the
metric to first post-Newtonian order. Surprisingly, we find that the PPN
parameters are exactly the same as in General Relativity (GR), and no
preferred-frame effects are produced. In particular this means that n-DBI
gravity is consistent with all GR solar system experimental tests. We discuss
the origin of such degeneracy between n-DBI gravity and GR, and suggest it may
also hold in higher post-Newtonian order. Secondly, we study gravitational
scalar perturbations of a Friedmann-Robertson-Walker space-time with a
cosmological constant $\Lambda \geq 0$. In the case of de Sitter space, we show
that the scalar mode grows as the universe expands and, in contrast with a
canonical scalar field coupled to GR, it does not freeze on super horizon
scales.


title:
The role of SE(d)-reduction for swimming in Stokes and Navier-Stokes
  fluids

abstract:
  Steady swimming appears both periodic and stable. These characteristics are
the very definition of limit cycles, and so we ask "Can we view swimming as a
limit cycle?" In this paper we will not be able to answer this question in
full. However, we shall find that reduction by SE(d)-symmetry brings us closer.
Upon performing reduction by symmetry, we will find a stable fixed point which
corresponds to a motionless body in stagnant water. We will then speculate on
the existence of periodic orbits which are "approximately" limit cycles in the
reduced system. When we lift these periodic orbits from the reduced phase
space, we obtain dynamically robust relatively periodic orbits wherein each
period is related to the previous by an SE(d)-phase. Clearly, an SE(d) phase
consisting of nonzero translation and identity rotation means directional
swimming, while non-trivial rotations correspond to turning with a constant
turning radius.