title:
$gl_{n+1}$ algebra of Matrix Differential Operators and Matrix
  Quasi-exactly-solvable Problems

abstract:
  The generators of the algebra $gl_{n+1}$ in a form of differential operators
of the first order acting on ${\bf R}^n$ with matrix coefficients are
explicitly written. The algebraic Hamiltonians for a matrix generalization of
$3-$body Calogero and Sutherland models are presented.


title:
CORN: Correlation-Driven Nonparametric Learning Approach for Portfolio
  Selection -- an Online Appendix

abstract:
  This appendix proves CORN's universal consistency. One of Bin's PhD thesis
examiner (Special thanks to Vladimir Vovk from Royal Holloway, University of
London) suggested that CORN is universal and provided sketch proof of Lemma
1.6, which is the key of this proof. Based on the proof in Gy\"prfi et al.
[2006], we thus prove CORN's universal consistency. Note that the notations in
this appendix follows Gy\"orfi et al. [2006].


title:
Boltzmann Model for viscoelastic particles: asymptotic behavior,
  pointwise lower bounds and regularity

abstract:
  We investigate the long time behavior of a system of viscoelastic particles
modeled with the homogeneous Boltzmann equation. We prove the existence of a
universal Maxwellian intermediate asymptotic state and explicit the rate of
convergence towards it. Exponential lower pointwise bounds and propagation of
regularity are also studied. These results can be seen as the generalization of
several classical facts holding for the pseudo-Maxwellian and constant normal
restitution models.


title:
The origins of $k^{-2}$ spectrum in the decaying Taylor-Green
  magnetohydrodynamic turbulent flows

abstract:
  We investigate the origins of $k^{-2}$ spectrum in a decaying Taylor-Green
magnetohydrodynamic flow with zero large scale magnetic flux that was reported
in Lee et al. (2010). A possible candidate for this scaling exponent has been
the weak turbulence phenomenology. From our numerical simulations, we observe
that current sheets in the magnetic Taylor-Green flow are formed in regions of
magnetic discontinuities. Based on this observation and by studying the
influence of the current sheets on the energy spectrum, using a filtering
technique, we argue that the discontinuities are responsible for the $-2$ power
law scaling of the energy spectra of this flow.


title: Three dimensional evolution of SN 1987A in a self-gravitating disk

abstract:
  The introduction of a exponential or power law gradient in the interstellar
medium (ISM) allows to produce an asymmetric evolution of the supernova remnant
(SNR) when the framework of the thin layer approximation is adopted.
Unfortunately both the exponential and power law gradients for the ISM do not
have a well defined physical meaning. The physics conversely is well
represented by an isothermal self-gravitating disk of particles whose velocity
is everywhere Maxwellian. . We derived a law of motion in the framework of the
thin layer approximation with a control parameter of the swept mass. The
photon's losses ,that are often neglected in the thin layer approximation, are
modeled trough a velocity dependence. The developed framework is applied to SNR
1987A and the three observed rings are simulated.


title: A New Cluster of Galaxies towards the Galactic Bulge, Suzaku J1759-3450

abstract:
  We observed an extended X-ray source designated as Suzaku J1759-3450 with the
Suzaku and Chandra observations towards 1RXS J175911.0-344921, which is an
unidentified X-ray source listed in the ROSAT Bright Source Catalogue. A
conspicuous emission line at 6 keV was also found in the Suzaku J1759-3450
spectrum. Assuming the emission line to be K emission from He-like Fe ions, we
inferred Suzaku J1759-3450 to be an extragalactic object located at z = 0.13.
The radial profile of the surface brightness in the 0.5-10 keV band was
explained well with an isothermal beta-model of r_c = 1.61' and beta = 0.78.
The X-ray spectrum was well reproduced by an optically-thin thermal plasma with
the electron temperature of kT_e = 5.3 keV attenuated by the photoelectric
absorption of N_H = 2.3 x 10^21 cm^-2. The bolometric X-ray luminosity of L_X
(r < r_500) = 4.3 x 10^44 erg s^-1 is consistent with that expected from the
L_X-T relation of clusters of galaxies. In terms of the spatial extent, the
X-ray spectrum, and the bolometric luminosity of the X-ray emitting gas, we
concluded that Suzaku J1759-3450 is a new cluster of galaxies.


title: Time weakens the Bell's inequalities

abstract:
  By taking into account that all real measurements are performed successively,
during time, it is concluded that the violation of the Bell's inequalities in
the Nature does not refute (even in an ideally perfect experiment) the theories
holding to Local Realism, for an unavoidable additional assumption is involved.
Yet, in order to be acceptable, such theories must predict different values for
the factual and counterfactual time averages of probabilities or observables.


title:
Exploring the threshold behavior and implications on the nature of
  Y(4260) and $Z_c(3900)$

abstract:
  By assuming that Y(4260) either is a $D_1\bar{D}$ molecular state, or has
sizeable couplings with $D_0 \bar{D}^*$ and $D_1^\prime \bar{D}$, we
investigate several decay modes of Y(4260). Under the special kinematic
configurations, triangle singularity (TS) may occur in the rescattering
amplitude, which will significantly change the threshold behavior. Obvious
threshold enhancements or narrow cusp structures appear quite naturally without
introducing a genuine resonance. We emphasize that the radiative decay modes
may be useful for studying $D^{(*)}\bar{D}$ $S$-wave scattering.


title:
Re-entrant Disordered Phase in a System of Repulsive Rods on a
  Bethe-like Lattice

abstract:
  We solve exactly a model of monodispersed rigid rods of length $k$ with
repulsive interactions on the random locally tree like layered lattice. For
$k\geq 4$ we show that with increasing density, the system undergoes two phase
transitions: first from a low density disordered phase to an intermediate
density nematic phase and second from the nematic phase to a high density
re-entrant disordered phase. When the coordination number is $4$, both the
phase transitions are continuous and in the mean field Ising universality
class. For even coordination number larger than $4$, the first transition is
discontinuous while the nature of the second transition depends on the rod
length $k$ and the interaction parameters.


title:
Notes on the sum of powers of the signless Laplacian eigenvalues of
  graphs

abstract:
  For a graph $G$ and a non-zero real number $\alpha$, the graph invariant
$S_{\alpha}(G)$ is the sum of the $\alpha^{th}$ power of the non-zero signless
Laplacian eigenvalues of $G$. In this paper, we obtain the sharp bounds of
$S_{\alpha}(G)$ for a connected bipartite graph $G$ on $n$ vertices and a
connected graph $G$ on $n$ vertices having a connectivity less than or equal to
$k$, respectively, and propose some open problems for future research.


title:
Imaging of Relaxation Times and Microwave Field Strength in a
  Microfabricated Vapor Cell

abstract:
  We present a new characterisation technique for atomic vapor cells, combining
time-domain measurements with absorption imaging to obtain spatially resolved
information on decay times, atomic diffusion and coherent dynamics. The
technique is used to characterise a 5 mm diameter, 2 mm thick microfabricated
Rb vapor cell, with N$_2$ buffer gas, placed inside a microwave cavity.
Time-domain Franzen and Ramsey measurements are used to produce high-resolution
images of the population ($T_1$) and coherence ($T_2$) lifetimes in the cell,
while Rabi measurements yield images of the $\sigma_-$, $\pi$ and $\sigma_+$
components of the applied microwave magnetic field. For a cell temperature of
90$^{\circ}$C, the $T_1$ times across the cell centre are found to be a roughly
uniform $265\,\mu$s, while the $T_2$ times peak at around $350\,\mu$s. We
observe a `skin' of reduced $T_1$ and $T_2$ times around the edge of the cell
due to the depolarisation of Rb after collisions with the silicon cell walls.
Our observations suggest that these collisions are far from being 100$\%$
depolarising, consistent with earlier observations made with Na and glass
walls. Images of the microwave magnetic field reveal regions of optimal field
homogeneity, and thus coherence. Our technique is useful for vapor cell
characterisation in atomic clocks, atomic sensors, and quantum information
experiments.


title: Slipping motion of large neutrally-buoyant particles in turbulence

abstract:
  Direct numerical simulations are used to investigate the individual dynamics
of large spherical particles suspended in a developed homogeneous turbulent
flow. A definition of the direction of the particle motion relative to the
surrounding flow is introduced and used to construct the mean fluid velocity
profile around the particle. This leads to an estimate of the particle slipping
velocity and its associated Reynolds number. The flow modifications due to the
particle are then studied. The particle is responsible for a shadowing effect
that occurs in the wake up to distances of the order of its diameter: the
particle pacifies turbulent fluctuations and reduces the energy dissipation
rate compared to its average value in the bulk. Dimensional arguments are
presented to draw an analogy between particle effects on turbulence and wall
flows. Evidence is obtained on the presence of a logarithmic sublayer at
distances between the thickness of the viscous boundary layer and the particle
diameter $\Dp$. Finally, asymptotic arguments are used to relate the viscous
sublayer quantities to the particle size and the properties of the outer
turbulence. It is shown in particular that the skin-friction Reynolds number
behaves as $Re_\tau \propto (\Dp/\eta)^{4/3}$.


title: Black Hole Universe: Time Evolution

abstract:
  Time evolution of a black hole lattice universe is simulated. The vacuum
Einstein equations in a cubic box with a black hole at the origin are
numerically solved with periodic boundary conditions on all pairs of opposite
faces. Defining effective scale factors by using the area of a surface and the
length of an edge of the cubic box, we compare them with that in the
Einstein-deSitter universe. It is found that the behaviour of the effective
scale factors is well approximated by that in the Einstein-deSitter universe.
Our result suggests that local inhomogeneities do not significantly affect the
global expansion law of the universe even if the inhomogeneity is extremely
nonlinear.


title:
Reduction of Mathematical Models of Nuclear Receptor Binding to Promoter
  Regions

abstract:
  We study kinetic model of Nuclear Receptor Binding to Promoter Regions. This
model is written as a system of ordinary differential equations. Model
reduction techniques have been used to simplify chemical kinetics.In this case
study, the technique of Pseudo-first order approximation is applied to simplify
the reaction rates. CellDesigner has been used to draw the structures of
chemical reactions of Nuclear Receptor Binding to Promoter Regions. After model
reduction, the general analytical solution for reduced model is given and the
number of species and reactions are reduced from 9 species and 6 reactions to 6
species and 5 reactions.


title: Measurement of the Luminosity in the ZEUS Experiment at HERA II

abstract:
  The luminosity in the ZEUS detector was measured using photons from electron
bremsstrahlung. In 2001 the HERA collider was upgraded for operation at higher
luminosity. At the same time the luminosity-measuring system of the ZEUS
experiment was modified to tackle the expected higher photon rate and
synchrotron radiation. The existing lead-scintillator calorimeter was equipped
with radiation hard scintillator tiles and shielded against synchrotron
radiation. In addition, a magnetic spectrometer was installed to measure the
luminosity independently using photons converted in the beam-pipe exit window.
The redundancy provided a reliable and robust luminosity determination with a
systematic uncertainty of 1.7%. The experimental setup, the techniques used for
luminosity determination and the estimate of the systematic uncertainty are
reported.


title:
PyHST2: an hybrid distributed code for high speed tomographic
  reconstruction with iterative reconstruction and a priori knowledge
  capabilities

abstract:
  We present the PyHST2 code which is in service at ESRF for phase-contrast and
absorption tomography. This code has been engineered to sustain the high data
flow typical of the third generation synchrotron facilities (10 terabytes per
experiment) by adopting a distributed and pipelined architecture. The code
implements, beside a default filtered backprojection reconstruction, iterative
reconstruction techniques with a-priori knowledge. These latter are used to
improve the reconstruction quality or in order to reduce the required data
volume and reach a given quality goal. The implemented a-priori knowledge
techniques are based on the total variation penalisation and a new recently
found convex functional which is based on overlapping patches.
  We give details of the different methods and their implementations while the
code is distributed under free license.
  We provide methods for estimating, in the absence of ground-truth data, the
optimal parameters values for a-priori techniques.


title:
Experimental access to higher-order Zeeman effects by precision
  spectroscopy of highly charged ions in a Penning trap

abstract:
  We present an experimental concept and setup for laser-microwave
double-resonance spectroscopy of highly charged ions in a Penning trap. Such
spectroscopy allows a highly precise measurement of the Zeeman splittings of
fine- and hyperfine-structure levels due the magnetic field of the trap. We
have performed detailed calculations of the Zeeman effect in the framework of
quantum electrodynamics of bound states as present in such highly charged ions.
We find that apart from the linear Zeeman effect, second- and third-order
Zeeman effects also contribute to the splittings on a level of 10^-4 and 10^-8,
respectively, and hence are accessible to a determination within the achievable
spectroscopic resolution of the ARTEMIS experiment currently in preparation.


title:
A Cloud Computing Survey: Developments and Future Trends in
  Infrastructure as a Service Computing

abstract:
  Cloud computing is a recent paradigm based around the notion of delivery of
resources via a service model over the Internet. Despite being a new paradigm
of computation, cloud computing owes its origins to a number of previous
paradigms. The term cloud computing is well defined and no longer merits
rigorous taxonomies to furnish a definition. Instead this survey paper
considers the past, present and future of cloud computing. As an evolution of
previous paradigms, we consider the predecessors to cloud computing and what
significance they still hold to cloud services. Additionally we examine the
technologies which comprise cloud computing and how the challenges and future
developments of these technologies will influence the field. Finally we examine
the challenges that limit the growth, application and development of cloud
computing and suggest directions required to overcome these challenges in order
to further the success of cloud computing.


title:
Parallel and perpendicular turbulence correlation length in the TJ-II
  Stellarator

abstract:
  Long range correlations were measured using two remote reciprocating Langmuir
probe systems at TJ-II. The influence of the rotational transform on the
correlation was studied by scanning the magnetic configuration. A simple drift
wave correlation model, assuming an exponential decay of the correlation with
different correlation lengths in the directions parallel and perpendicular to
the field lines, was found to describe the observations well at low densities.
The experiment was repeated at gradually higher densities, and an additional
correlation was detected at a critical value of the density. In accordance with
previous work, this additional correlation was ascribed to zonal flows
associated with a confinement transition. Thus, the total long range
correlation is found to be a sum of the drift wave and zonal flow
contributions.


title:
Spin Magnetic Moment and Persistent Orbital Currents in Cylindrical
  Nanolayer

abstract:
  Densities of persistent orbital and spin magnetic moment currents of an
electron in a cylindrical nanolayer in the presence of external axial magnetic
field are considered. For the mentioned current densities analytical
expressions are obtained. The conditions when in the system only spin magnetic
moment current is present are defined. Dependencies of orbital and spin
magnetic moment currents on geometrical parameters of nanolayer are derived. It
is shown that in the case of layered geometry the dependence of spin magnetic
moment current on radial coordinate has a non-monotonic behavior. This is the
peculiarity of layered geometry of nanostructure and it is due to the behavior
of wave function of the system along the radial direction. Dependent on the
directions of the field and orbital rotation of the electron there are defined
values of radial coordinates when the orbital current disappears. The
transition to the case of cylindrical quantum dot is discussed as well.


title:
Estimating arrival time of Earth-directed CMEs at \textit{in-situ}
  spacecraft using COR & HI observations from STEREO

abstract:
  The prediction of the arrival time and transit speed of CMEs near the Earth
is one of the key problems in understanding the solar terrestrial relationship.
Although, STEREO observations now provide a multiple view of CMEs in the
heliosphere, the true speeds derived from stereoscopic reconstruction of SECCHI
coronagraph data are not quite sufficient in accurate forecasting of arrival
time of a majority of CMEs at the Earth. This is due to many factors which
change the CME kinematics, like interaction of two or more CMEs or the
interaction of CMEs with the pervading solar wind. In order to understand the
propagation of CMEs, we have used the 3D triangulation method on SECCHI
coronagraph (COR2) images, and geometric triangulation on the J-maps
constructed from Heliospheric Imagers HI1 and HI2 images for eight
Earth-directed CMEs observed during 2008-2010. Based on the reconstruction, and
implementing the Drag Based Model for the distance where the CMEs could not be
tracked unambiguously in the interplanetary medium, the arrival time of these
CMEs have been estimated. These arrival times have also been compared with the
actual arrival time as observed by \textit{in-situ} instruments. The analysis
reveals the importance of heliospheric imaging for improved forecasting of the
arrival time and direction of propagation of CMEs in the interplanetary medium.


title:
Curve shortening-straightening flow for non-closed planar curves with
  infinite length

abstract:
  We consider a motion of non-closed planar curves with infinite length. The
motion is governed by a steepest descent flow for the geometric functional
which consists of the sum of the length functional and the total squared
curvature. We call the flow shortening-straightening flow. In this paper, first
we prove a long time existence result for the shortening-straightening flow for
non-closed planar curves with infinite length. Then we show that the solution
converges to a stationary solution as time goes to infinity. Moreover we give a
classification of the stationary solution.


title:
What can the spatial distribution of galaxy clusters tell about their
  scaling relations?

abstract:
  We aim to quantify the capability of the inhomogeneous distribution of galaxy
clusters, represented by the two-point statistics in Fourier space, to retrieve
information on the underlying scaling relations. We make a case study using the
mass X-ray luminosity scaling relation for galaxy clusters and study its impact
on the clustering pattern of these objects. We define the luminosity-weighted
power spectrum and introduce the luminosity power spectrum as direct assessment
of the clustering of the property of interest, in our case, the cluster X-ray
luminosity. Using a suite of halo catalogs extracted from N-body simulations
and realistic estimates of the mass X-ray luminosity relation, we measured
these statistics with their corresponding covariance matrices. By carrying out
a Fisher matrix analysis, we quantified the content of information (by means of
a figure-of merit) encoded in the amplitude, shape, and full shape of our
probes for two-point statistics. The full shape of the luminosity power
spectrum, when analyzed up to scales of k~0.2 h/Mpc, yields a figure of merit
which is two orders of magnitude above the figure obtained from the unweighted
power spectrum, and only one order of magnitude below the value encoded in
X-ray luminosity function estimated from the same sample. This is a significant
improvement over the analysis developed with the standard (i.e., unweighted)
clustering probes. The measurements of the clustering of galaxy clusters and
its explicit dependence on the cluster intrinsic properties can contribute to
improving the degree of knowledge regarding the underlying links between
cluster observables and the cluster masses (Abridged).


title:
On reduction of moduli schemes of abelian varieties with definite
  quaternion multiplications

abstract:
  In this paper we make an initial study on type D moduli spaces in positive
characteristic $p\neq 2$, where we allow $p$ ramified in the definite
quaternion algebra. We classify the isogeny classes of $p$-divisible groups
with additional structures in question. We also study the reduction of the type
$D$ moduli spaces of minimal rank.


title:
Optical correlation techniques for the investigation of colloidal
  systems

abstract:
  This review aims to provide a simple introduction to the application of
optical correlation methods in colloidal science. In particular, I plan to show
that full appraisal of the intimate relation between light scattering and
microscopy allows designing novel powerful investigation techniques that
combine their powers. An extended version of this paper will appear in
"ColloidalFoundations of Nanoscience", edited by D. Berti and G. Palazzo,
Elsevier (ISBN 978-0-444-59541-6). I am very grateful to the publisher for
having granted me the permission to post this preprint on arXiv.


title: Threshold Load Balancing in Networks

abstract:
  We study probabilistic protocols for concurrent threshold-based load
balancing in networks. There are n resources or machines represented by nodes
in an undirected graph and m >> n users that try to find an acceptable resource
by moving along the edges of the graph. Users accept a resource if the load is
below a threshold. Such thresholds have an intuitive meaning, e.g., as
deadlines in a machine scheduling scenario, and they allow the design of
protocols under strong locality constraints. When migration is partly
controlled by resources and partly by users, our protocols obtain rapid
convergence to a balanced state, in which all users are satisfied. We show that
convergence is achieved in a number of rounds that is only logarithmic in m and
polynomial in structural properties of the graph. Even when migration is fully
controlled by users, we obtain similar results for convergence to approximately
balanced states. If we slightly adjust the migration probabilities in our
protocol, we can also obtain fast convergence to balanced states.


title: Enumeration of symmetric centered rhombus tilings of a hexagon

abstract:
  A rhombus tiling of a hexagon is said to be centered if it contains the
central lozenge. We compute the number of vertically symmetric rhombus tilings
of a hexagon with side lengths $a, b, a, a, b, a$ which are centered. When $a$
is odd and $b$ is even, this shows that the probability that a random
vertically symmetric rhombus tiling of a $a, b, a, a, b, a$ hexagon is centered
is exactly the same as the probability that a random rhombus tiling of a $a, b,
a, a, b, a$ hexagon is centered. This also leads to a factorization theorem for
the number of all rhombus tilings of a hexagon which are centered.


title: Observables in Strongly Coupled Anisotropic Theories

abstract:
  We review certain anisotropic gauge/gravity dualities, focusing more on a
theory with space dependent axion term. Then we discuss and also present some
new results for several observables: the static potential and force, the
imaginary part of the static potential, the quark dipole in the plasma wind,
the drag force and diffusion time, the jet quenching of heavy and light quarks,
the energy loss of rotating quarks, the photon production and finally the
violation of the holographic viscosity over entropy bound. The corresponding
weakly coupled results are also discussed. Finally we investigate the bounds of
the parameters of the current strongly coupled anisotropic theories attempting
to match them with the observed quark-gluon plasma and report the problems
appear.


title: Energy Feedback from X-ray Binaries in the Early Universe

abstract:
  X-ray photons, because of their long mean-free paths, can easily escape the
galactic environments where they are produced, and interact at long distances
with the inter-galactic medium, potentially having a significant contribution
to the heating and reionization of the early Universe. The two most important
sources of X-ray photons in the Universe are active galactic nuclei (AGN) and
X-ray binaries (XRBs). In this Letter we use results from detailed, large scale
population synthesis simulations to study the energy feedback of XRBs, from the
first galaxies (z~ 20) until today. We estimate that X-ray emission from XRBs
dominates over AGN at z>6-8. The shape of the spectral energy distribution of
the emission from XRBs shows little change with redshift, in contrast to its
normalization which evolves by ~4 orders of magnitude, primarily due to the
evolution of the cosmic star-formation rate. However, the metallicity and the
mean stellar age of a given XRB population affect significantly its X-ray
output. Specifically, the X-ray luminosity from high-mass XRBs per unit of
star-formation rate varies an order of magnitude going from solar metallicity
to less than 10% solar, and the X-ray luminosity from low-mass XRBs per unit of
stellar mass peaks at an age of ~300 Myr and then decreases gradually at later
times, showing little variation for mean stellar ages > 3 Gyr. Finally, we
provide analytical and tabulated prescriptions for the energy output of XRBs,
that can be directly incorporated in cosmological simulations.


title: Convergence to equilibrium of gradient flows defined on planar curves

abstract:
  We consider the evolution of open planar curves by the steepest descent flow
of a geometric functional, under different boundary conditions. We prove that,
if any set of stationary solutions with fixed energy is finite, then a solution
of the flow converges to a stationary solution as time goes to infinity. We
also present a few applications of this result.


title:
In-plane electronic confinement in superconducting LaAlO$_3$/SrTiO$_3$
  nanostructures

abstract:
  We describe the transport properties of mesoscopic devices based on the two
dimensional electron gas (2DEG) present at the LaAlO$_3$/SrTiO$_3$ interface.
Bridges with lateral dimensions down to 500~nm were realized using electron
beam lithography. Their detailed characterization shows that processing and
confinement do not alter the transport parameters of the 2DEG. The devices
exhibit superconducting behavior tunable by electric field effect. In the
normal state, we measured universal conductance fluctuations, signature of
phase-coherent transport in small structures. The achievement of reliable
lateral confinement of the 2DEG opens the way to the realization of quantum
electronic devices at the LaAlO$_3$/SrTiO$_3$ interface.


title:
Dynamic Clustering Protocol for Data Forwarding in Wireless Sensor
  Networks

abstract:
  Energy being the very key concern area with sensor networks, so the main
focus lies in developing a mechanism to increase the lifetime of a sensor
network by energy balancing. To achieve energy balancing and maximizing network
lifetime we use an idea of clustering and dividing the whole network into
different clusters. In this paper we propose a dynamic cluster formation method
where clusters are refreshed periodically based on residual energy, distance
and cost. Refreshing clustering minimizes workload of any single node and in
turn enhances the energy conservation. Sleep and wait methodology is applied to
the proposed protocol to enhance the network lifetime by turning the nodes on
and off according to their duties. The node that has some data to be
transmitted is in on state and after forwarding its data to the cluster head it
changes its state to off which saves the energy of entire network. Simulations
have been done using MAT lab. Simulation results prove the betterment of our
proposed method over the existing Leach protocol.


title:
Asymptotics for the number of spanning trees in circulant graphs and
  degenerating d-dimensional discrete tori

abstract:
  In this paper we obtain precise asymptotics for certain families of graphs,
namely circulant graphs and degenerating discrete tori. The asymptotics contain
interesting constants from number theory among which some can be interpreted as
corresponding values for continuous limiting objects. We answer one question
formulated in a paper from Atajan, Yong and Inaba in [1] and formulate a
conjecture in relation to the paper from Zhang, Yong and Golin [21]. A crucial
ingredient in the proof is to use the matrix tree theorem and express the
combinatorial laplacian determinant in terms of Bessel functions. A
non-standard Poisson summation formula and limiting properties of theta
functions are then used to evaluate the asymptotics.


title:
Computing the Cassels-Tate pairing on the 3-Selmer group of an elliptic
  curve

abstract:
  We extend the method of Cassels for computing the Cassels-Tate pairing on the
2-Selmer group of an elliptic curve, to the case of 3-Selmer groups. This
requires significant modifications to both the local and global parts of the
calculation. Our method is practical in sufficiently small examples, and can be
used to improve the upper bound for the rank of an elliptic curve obtained by
3-descent.


title: Dark Matter investigation by DAMA at Gran Sasso

abstract:
  Experimental observations and theoretical arguments at Galaxy and larger
scales have suggested that a large fraction of the Universe is composed by Dark
Matter particles. This has motivated the DAMA experimental efforts to
investigate the presence of such particles in the galactic halo by exploiting a
model independent signature and very highly radiopure set-ups deep underground.
Few introductory arguments are summarized before presenting a review of the
present model independent positive results obtained by the DAMA/NaI and
DAMA/LIBRA set-ups at the Gran Sasso National Laboratory of the INFN.
Implications and model dependent comparisons with other different kinds of
results will be shortly addressed. Some arguments put forward in literature
will be confuted.


title: Hydrostatic strain enhancement in laterally confined SiGe nanostripes

abstract:
  Strain-engineering in SiGe nanostructures is fundamental for the design of
optoelectronic devices at the nanoscale. Here we explore a new strategy, where
SiGe structures are laterally confined by the Si substrate, to obtain high
tensile strain avoiding the use of external stressors, and thus improving the
scalability. Spectro-microscopy techniques, finite element method simulations
and ab initio calculations are used to investigate the strain state of
laterally confined Ge-rich SiGe nano-stripes. Strain information is obtained by
tip enhanced Raman spectroscopy with an unprecedented lateral resolution of ~
30 nm. The nano-stripes exhibit a large tensile hydrostatic strain component,
which is maximum at the center of the top free surface, and becomes very small
at the edges. The maximum lattice deformation is larger than the typical values
of thermally relaxed Ge/Si(001) layers. This strain enhancement originates from
a frustrated relaxation in the out-of-plane direction, resulting from the
combination of the lateral confinement induced by the substrate side walls and
the plastic relaxation of the misfit strain in the (001) plane at the SiGe/Si
interface. The effect of this tensile lattice deformation at the stripe surface
is probed by work function mapping, performed with a spatial resolution better
than 100 nm using X-ray photoelectron emission microscopy. The nano-stripes
exhibit a positive work function shift with respect to a bulk SiGe alloy,
quantitatively confirmed by electronic structure calculations of tensile
strained configurations. The present results have a potential impact on the
design of optoelectronic devices at a nanometer length scale.


title:
Determination of the Entropy via Measurement of the Magnetization:
  Application to the Spin ice Dy2Ti2O7

abstract:
  The residual entropy of spin ice and other frustrated magnets is a property
of considerable interest, yet the usual way of determining it, by integrating
the heat capacity, is generally ambiguous. Here we note that a straightforward
alternative method based on Maxwell's thermodynamic relations can yield the
residual entropy on an absolute scale. The method utilises magnetization
measurements only and hence is a useful alternative to calorimetry. We confirm
that it works for spin ice, Dy2Ti2O7, which recommends its application to other
systems. The analysis described here also gives an insight into the dependence
of entropy on magnetic moment, which plays an important role in the theory of
magnetic monopoles in spin ice. Finally, we present evidence of a field-induced
crossover from correlated spin ice behaviour to ordinary paramagnetic behaviour
with increasing applied field, as signalled by a change in the effective Curie
constant.


title:
Magnetoelectric effect in topological insulator films beyond the linear
  response regime

abstract:
  We study the response of topological insulator films to strong magnetic and
electric fields beyond the linear response theory. As a model, we use the
three-dimensional lattice Wilson-Dirac Hamiltonian where we simultaneously
introduce both magnetic field through the Peierls substitution and electric
field as a potential energy depending on lattice coordinate. We compute the
electron energy spectrum by numerically diagonalizing this Hamiltonian and
obtain quantized magnetoelectric polarizability. In addition, we find that the
magnetoelectric effect vanishes as the film width decreases due to the
hybridization of surface wave functions. Furthermore, applying a gate voltage
between the surfaces, we observe several quantized plateaus of $\theta$ term,
which are mainly determined by the Landau level structures on the top and
bottom surfaces.


title:
Voltage control of electron-nuclear spin correlation time in a single
  quantum dot

abstract:
  We demonstrate bias control of the hyperfine coupling between a single
electron in an InAs quantum dot and the surrounding nuclear spins monitored
through the positively charged exciton X+ emission. In applied longitudinal
magnetic fields we vary simultaneously the correlation time of the hyperfine
interaction and the nuclear spin relaxation time and thereby the amplitude of
the achieved dynamic nuclear polarization under optical pumping conditions. In
applied transverse magnetic fields a change in the applied bias allows to
switch from the anomalous Hanle effect to the standard electron spin
depolarization curves.


title:
Measuring molecular electric dipoles using trapped atomic ions and
  ultrafast laser pulses

abstract:
  We study a hybrid quantum system composed of an ion and an electric dipole.
We show how a trapped ion can be used to measure the small electric field
generated by a classical dipole. We discuss the application of this scheme to
measure the electric dipole moment of cold polar molecules, whose internal
state can be controlled with ultrafast laser pulses, by trapping them in the
vicinity of a trapped ion.


title: Blow up of solutions of semilinear heat equations in general domains

abstract:
  Consider the nonlinear heat equation $v_t -\Delta v= |v|^{p-1} v$ in a
bounded smooth domain $\Omega\subset \R^n$ with $n>2$ and Dirichlet boundary
condition. Given $u_{p}$ a sign-changing stationary solution fulfilling
suitable assumptions, we prove that the solution with initial value $\theta
u_{p} $ blows up in finite time if $ |\theta -1|>0$ is sufficiently small and
if $p$ is sufficiently close to the critical exponent.
  Since for $\theta=1$ the solution is global, this shows that, in general, the
set of the initial data for which the solution is global is not star-shaped.
This phenomenon had been previously observed in the case when the domain is a
ball and the stationary solution is radially symmetric.


title: A note on unique continuation for discrete harmonic functions

abstract:
  In this note we give a quantitative version of the following simple
observation: a discrete harmonic function on the lattice may vanish at each
point of a large cube without being zero identically, at the same time there is
a version of three balls theorem for discrete harmonic functions since they
resemble continuous ones on large scales.


title: $\mathcal{PT}$-symmetric strings

abstract:
  We study both analytically and numerically the spectrum of inhomogeneous
strings with $\mathcal{PT}$-symmetric density. We discuss an exactly solvable
model of $\mathcal{PT}$-symmetric string which is isospectral to the uniform
string; for more general strings, we calculate exactly the sum rules $Z(p)
\equiv \sum_{n=1}^\infty 1/E_n^p$, with $p=1,2,\dots$ and find explicit
expressions which can be used to obtain bounds on the lowest eigenvalue. A
detailed numerical calculation is carried out for two non-solvable models
depending on a parameter, obtaining precise estimates of the critical values
where pair of real eigenvalues become complex.


title:
Quantum computational universality of spin-3/2
  Affleck-Kennedy-Lieb-Tasaki states beyond the honeycomb lattice

abstract:
  Universal quantum computation can be achieved by simply performing
single-spin measurements on a highly entangled resource state, such as cluster
states. The family of Affleck-Kennedy-Lieb-Tasaki (AKLT) states has recently
been explored; for example, the spin-1 AKLT chain can be used to simulate
single-qubit gate operations on a single qubit, and the spin-3/2
two-dimensional AKLT state on the honeycomb lattice can be used as a universal
resource. However, it is unclear whether such universality is a coincidence for
the specific state or a shared feature in all two-dimensional AKLT states. Here
we consider the family of spin-3/2 AKLT states on various trivalent Archimedean
lattices and show that in addition to the honeycomb lattice, the spin-3/2 AKLT
states on the square octagon $(4,8^2)$ and the `cross' $(4,6,12)$ lattices are
also universal resource, whereas the AKLT state on the `star' $(3,12^2)$
lattice is likely not due to geometric frustration.


title:
Bayesian Inference of Natural Rankings in Incomplete Competition
  Networks

abstract:
  Competition between a complex system's constituents and a corresponding
reward mechanism based on it have profound influence on the functioning,
stability, and evolution of the system. But determining the dominance hierarchy
or ranking among the constituent parts from the strongest to the weakest --
essential in determining reward or penalty -- is almost always an ambiguous
task due to the incomplete nature of competition networks. Here we introduce
``Natural Ranking," a desirably unambiguous ranking method applicable to a
complete (full) competition network, and formulate an analytical model based on
the Bayesian formula inferring the expected mean and error of the natural
ranking of nodes from an incomplete network. We investigate its potential and
uses in solving issues in ranking by applying to a real-world competition
network of economic and social importance.

categories: physics.soc-ph cs.AI cs.SI physics.data-an


title:
Space-borne gravitational wave detectors as time-delayed differential
  dynamometers

abstract:
  The basic constituent of many space-borne gravitational missions, in
particular for interferometric gravitational waves detectors, is the so-called
link made out of a satellite sending an electromagnetic beam to a second
satellite. We illustrate how, by measuring the time derivative of the frequency
of the received beam, the link behaves as a differential, time-delayed
dynamometer in which the effect of gravity is exactly equivalent to an
effective differential force applied to the two satellites. We also show that
this differential force gives an integrated measurement of curvature along the
beam. Finally, we discuss how this approach can be implemented to benefit the
data analysis of gravitational wave detectors.


title:
Measuring the Mass Hierarchy with Muon and Hadron Events in Atmospheric
  Neutrino Experiments

abstract:
  Neutrino mass hierarchy can be measured in atmospheric neutrino experiments
through the observation of earth matter effects. Magnetized iron calorimeters
have been shown to be good in this regard due to their charge identification
capabilities. The charged current interaction of $\nu_\mu$ in this detector,
produces a muon track and a hadron shower. The direction of the muon track can
be measured very accurately. We show the improvement expected in the reach of
this class of experiments to the neutrino mass hierarchy, as we improve the
muon energy resolution and the muon reconstruction efficiency. We next propose
to include the hadron events in the analysis, by tagging them with the zenith
angle of the corresponding muon and binning the hadron data first in energy and
then in zenith angle. To the best of our knowledge this way of performing the
analysis of the atmospheric neutrino data has not be considered before. We show
that the hadron events increase the mass hierarchy sensitivity of the
experiment. Finally, we show the expected mass hierarchy sensitivity in terms
of the reconstructed neutrino energy and zenith angle. We show how the detector
resolutions spoil the earth matter effects in the neutrino channel and argue
why the sensitivity obtained from the neutrino analysis cannot be significantly
better than that obtained from the analysis using muon data alone. As a result,
the best mass hierarchy sensitivity is obtained when we add the contribution of
the muon and the hadron data. For $\sin^22\theta_{13}=0.1$,
$\sin^2\theta_{23}=0.5$, a muon energy resolution of 2\%, reconstruction
efficiency of 80\% and exposure of $50\times 10$ kton-year, we could get up to
$4.5\sigma$ signal for the mass hierarchy from combining the muon and hadron
data.


title:
Geometry of the Gromov product : Geometry at infinity of Teichm\"uller
  space

abstract:
  This paper is devoted to study of transformations on metric spaces. It is
done in an effort to produce qualitative version of quasi-isometries which
takes into account the asymptotic behavior of the Gromov product in hyperbolic
spaces. We characterize a quotient semigroup of such transformations on
Teichm\"uller space by use of simplicial automorphisms of the complex of
curves, and we will see that such transformation is recognized as a
"coarsification" of isometries on Teichm\"uller space which is rigid at
infinity. We also show a hyperbolic characteristic that any finite dimensional
Teichm\"uller space does not admit (quasi)-invertible rough-homothety.


title: Fundamental Physics with Imaging Atmospheric Cherenkov Telescopes

abstract:
  Ground-based gamma-ray astronomy experienced a major boost with the advent of
the present generation of Imaging Atmospheric Cherenkov Telescopes (IACTs) in
the past decade. Photons of energies >~ 0.1 TeV are a very useful tool in the
study of several fundamental physics topics, which have become an important
part of the research program of all major IACTs. A review of some recent
results in the field is presented.


title:
A modeling framework for Ordered Weighted Average Combinatorial
  Optimization

abstract:
  Multiobjective combinatorial optimization deals with problems considering
more than one viewpoint or scenario. The problem of aggregating multiple
criteria to obtain a globalizing objective function is of special interest when
the number of Pareto solutions becomes considerably large or when a single,
meaningful solution is required. Ordered Weighted Average or Ordered Median
operators are very useful when preferential information is available and
objectives are comparable since they assign importance weights not to specific
objectives but to their sorted values. In this paper, Ordered Weighted Average
optimization problems are studied from a modeling point of view. Alternative
integer programming formulations for such problems are presented and their
respective domains studied and compared. In addition, their associated
polyhedra are studied and some families of facets and new families of valid
inequalities presented. The proposed formulations are particularized for two
well-known combinatorial optimization problems, namely, shortest path and
minimum cost perfect matching, and the results of computational experiments
presented and analyzed. These results indicate that the new formulations
reinforced with appropriate constraints can be effective for efficiently
solving medium to large size instances.


title:
An asymptotically stable cusp-fold singularity in 3D piecewise smooth
  vector fields

abstract:
  This paper is concerned with the analysis of a typical singularity of
piecewise smooth vector fields on $R^3$ composed by two zones. In our object of
study, the cusp-fold singularity, we consider the simultaneous occurrence of a
cusp singularity for one vector field and a fold singularity for the other one.
We exhibit a normal form that presents one of the most important property
searched for in piecewise smooth vector fields: the asymptotical stability.


title: Quadratic Bounds on the Quasiconvexity of Nested Train Track Sequences

abstract:
  Let $S_{g,p}$ denote the genus $g$ orientable surface with $p$ punctures. We
show that nested train track sequences constitute $O((g,p)^{2})$-quasiconvex
subsets of the curve graph, effectivizing a theorem of Masur and Minsky. As a
consequence, the genus $g$ disk set is $O(g^{2})$-quasiconvex. We also show
that splitting and sliding sequences of birecurrent train tracks project to
$O((g,p)^{2})$-unparameterized quasi-geodesics in the curve graph of any
essential subsurface, an effective version of a theorem of Masur, Mosher, and
Schleimer.


title:
Rotational dynamics of an asymmetric top molecule in parallel electric
  and non-resonant laser fields

abstract:
  We present a theoretical study of the rotational dynamics of asymmetry top
molecules in an electric field and a parallel non-resonant linearly polarized
laser pulse. The time-dependent Schr\"odinger equation is solved within the
rigid rotor approximation. Using the benzonitrile molecule as prototype, we
investigate the field-dressed dynamics for experimentally accessible field
configurations and compare these results to the adiabatic predictions. We show
that for an asymmetric top molecule in parallel fields, the formation of the
pendular doublets and the avoided crossings between neighboring levels are the
two main sources of non-adiabatic effects. We also provide the field parameters
under which the adiabatic dynamics would be achieved.


title:
Large Time Behaviour and Convergence Rate for Non Demolition Quantum
  Trajectories

abstract:
  A quantum system S undergoing continuous time measurement is usually
described by a jump-diffusion stochastic differential equation. Such an
equation is called a stochastic master equation and its solution is called a
quantum trajectory. This solution describes actually the evolution of the state
of S. In the context of Quantum Non Demolition measurement, we investigate the
large time behavior of this solution. It is rigorously shown that, for large
time, this solution behaves as if a direct Von Neumann measurement has been
performed at time 0. In particular the solution converges to a random pure
state which is related to the wave packet reduction postulate. Using theory of
Girsanov transformation, we determine precisely the exponential rate of
convergence towards this random state. The important problem of state
estimation (used in experiment) is also investigated.


title:
Particle beam experiments for the investigation of plasma-surface
  interactions: application to magnetron sputtering and polymer treatment

abstract:
  A beam experiment is presented to study heterogeneous reactions relevant to
plasma-surface interactions. Atom and ion beams are focused onto the sample to
expose it to quantified beams of oxygen, nitrogen, hydrogen, noble gas ions and
metal vapor. The heterogeneous surface processes are monitored in-situ and in
real time by means of a quartz crystal microbalance (QCM) and Fourier transform
infrared spectroscopy (FTIR). Two examples illustrate the capabilities of the
particle beam setup: oxidation and nitriding of aluminum as a model of target
poisoning during reactive magnetron sputtering, and plasma treatment of
polymers (PET, PP).


title: A ternary construction of lattices

abstract:
  In this paper we propose a general ternary construction of lattices from
three rows and ternary codes. Most laminated lattices and Kappa lattices in
${\bf R}^n$, $n\leq 24$ can be recovered from our tenary construction
naturally. This ternary construction of lattices can be used to generate many
new "sub-optimal" lattices of low dimensions.Based on this ternary construction
new extremal even lattices of dimensions $32, 40$ and $48$ are also
constructed.


title:
Tight Lower Bound on the Probability of a Binomial Exceeding its
  Expectation

abstract:
  We give the proof of a tight lower bound on the probability that a binomial
random variable exceeds its expected value. The inequality plays an important
role in a variety of contexts, including the analysis of relative deviation
bounds in learning theory and generalization bounds for unbounded loss
functions.


title:
Origin of high-Tc superconductivity in doped Hubbard models and their
  extensions: Roles of uniform charge fluctuations

abstract:
  Doped Hubbard model is a simple model for the high-Tc cuprate
superconductors, while its ground state remains a challenge. Here, by
performing state-of-the-art variational Monte Carlo calculations for the
strong-coupling Hubbard model, we find evidences that the d-wave
superconducting phase emerges always near the phase separation region and the
superconducting order has one-to-one correspondence with the enhancement of
charge compressibility. The order as well as the phase separation are
vulnerable to realistic intersite Coulomb interaction while the superexchange
interaction enhances both. An appropriate combination of these two widens the
stable superconducting phase.


title:
On the abundance of primordial bound states of superheavy magnetic
  monopoles

abstract:
  It has been suggested that superheavy charged particles might have been born
in primordial bound pairs at the end of cosmic inflation. Such pairs have been
proposed as a source of ultra-high energy cosmic rays (UHECR). We show that
primordial bound pairs of magnetic monopoles larger than $10^{-9}$ cm quickly
thermolise due to the interaction with primordial electron-positron plasma and
any such initial primordial concentration is washed out. The final
concentration will therefore be defined by their equilibrium abundance.


title: An efficient group authentication for group communications

abstract:
  Group communication implies a many-to-many communication and it goes beyond
both one-to-one communication (i.e., unicast) and one-to-many communication
(i.e., multicast). Unlike most user authentication protocols that authenticate
a single user each time, we propose a new type of authentication, called group
authentication, that authenticates all users in a group at once. The group
authentication protocol is specially designed to support group communications.
There is a group manager who is responsible to manage the group communication.
During registration, each user of a group obtains an unique token from the
group manager. Users present their tokens to determine whether they all belong
to the same group or not. The group authentication protocol allows users to
reuse their tokens without compromising the security of tokens. In addition,
the group authentication can protect the identity of each user.


title:
On the continuity of Fourier multipliers on the homogeneous Sobolev
  spaces $\dot{W}^1_1(R^d)$

abstract:
  In this paper we proof that every Fourier multiplier on homogeneous sobolev
space $\dot{W}_1^1(\mathbb{R}^d)$ is a continuous function. Our theorem is
generalization of A. Bonami and S. Poornima result for Fourier multipliers,
which are homogeneous functions of degree zero.


title:
Global Rates of Convergence of the MLEs of Log-concave and s-concave
  Densities

abstract:
  We establish global rates of convergence for the Maximum Likelihood
Estimators (MLEs) of log-concave and $s$-concave densities on $\mathbb{R}$. The
main finding is that the rate of convergence of the MLE in the Hellinger metric
is no worse than $n^{-2/5}$ when $-1 < s < \infty$ where $s=0$ corresponds to
the log-concave case. We also show that the MLE does not exist for the classes
of $s$-concave densities with $s < - 1$.


title:
Protein structure prediction software generate two different sets of
  conformations. Or the study of unfolded self-avoiding walks

abstract:
  Self-avoiding walks (SAW) are the source of very difficult problems in
probabilities and enumerative combinatorics. They are also of great interest as
they are, for instance, the basis of protein structure prediction in
bioinformatics. Authors of this article have previously shown that, depending
on the prediction algorithm, the sets of obtained conformations differ: all the
self-avoiding walks can be reached using stretching-based algorithms whereas
only the folded SAWs can be attained with methods that iteratively fold the
straight line. A first study of (un)folded self-avoiding walks is presented in
this article. The contribution is majorly a survey of what is currently known
about these sets. In particular we provide clear definitions of various subsets
of self-avoiding walks related to pivot moves (folded or unfoldable SAWs, etc.)
and the first results we have obtained, theoretically or computationally, on
these sets. A list of open questions is provided too, and the consequences on
the protein structure prediction problem is finally investigated.


title: The Shape of Covariantly Smeared Sources in Lattice QCD

abstract:
  Covariantly smeared sources are commonly used in lattice QCD to enhance the
projection onto the ground state. Here we investigate the dependence of their
shape on the gauge field background and find that the presence of localized
concentrations of magnetic field can lead to strong distortions which reduce
the smearing radii achievable by iterative smearing prescriptions. In
particular, as $a\to 0$, iterative procedures like Jacobi smearing require
increasingly large iteration counts in order to reach physically-sized smearing
radii $r_{sm}\sim$ 0.5 fm, and the resulting sources are strongly distorted. To
bypass this issue, we propose a covariant smearing procedure (``free-form
smearing'') that allows us to create arbitrarily shaped sources, including in
particular Gaussians of arbitrary radius.


title:
Semimetal-superfluid quantum phase transitions in 2D and 3D lattices
  with Dirac points

abstract:
  We study the superfluid properties of attractively interacting fermions
hopping in a family of 2D and 3D lattices in the presence of synthetic gauge
fields having \pi-flux per plaquette. The reason for such a choice is that the
\pi-flux cubic lattice displays Dirac points and that decreasing the hopping
coefficient in a spatial direction (say, t_z) these Dirac points are unaltered:
it is then possible to study the 3D-2D interpolation towards the \pi-flux
square lattice. We also consider the lattice configuration providing the
continuous interpolation between the 2D \pi-flux square lattice and the
honeycomb geometry. We investigate by a mean field analysis the effects of
interaction and dimensionality on the superfluid gap, chemical potential and
critical temperature, showing that these quantities continuously vary along the
patterns of interpolation. In the two-dimensional cases at zero temperature and
at half filling there is a quantum phase transition occurring at a critical
(negative) interaction U_c presenting a linear critical exponent for the gap as
a function of |U-U_c|. We show that in three dimensions this quantum phase
transition is again retrieved, pointing out that the critical exponent for the
gap changes from 1 to 1/2 for each finite value of t_z.

categories: cond-mat.str-el cond-mat.mtrl-sci cond-mat.quant-gas cond-mat.supr-con


title:
Random close packing fractions of lognormal distributions of hard
  spheres

abstract:
  We apply a recent one-dimensional algorithm for predicting random close
packing fractions of polydisperse hard spheres [Farr and Groot, J. Chem. Phys.
133, 244104 (2009)] to the case of lognormal distributions of sphere sizes and
mixtures of such populations. We show that the results compare well to two much
slower algorithms for directly simulating spheres in three dimensions, and show
that the algorithm is fast enough to tackle inverse problems in particle
packing: designing size distributions to meet required criteria. The
one-dimensional method used in this paper is implemented as a computer code in
the C programming language, available at
http://sourceforge.net/projects/spherepack1d/ under the terms of the GNU
general public licence (version 2).


title:
Universal Optimal Gates Regarding Quantum Entanglement and Discord
  Generating

abstract:
  Fernando Galve \emph{et al.} $[Phys. Rev. Lett. \textbf{110}, 010501 (2013)]$
introduced discording power for a two-qubit unitary gate to evaluate its
capability to produce quantum discord, and found that a $\pi/8$ gate has
maximal discording power. This work analyzes the entangling power of a
two-qubit unitary gate, which reflects its ability to generate quantum
entanglement in another way. Based on the renowned Cartan decomposition of
two-qubit unitary gates, we show that the magic power of the $\pi/8$ gate
produces maximal entanglement for a general value of purities for two-qubit
states.


title: The boundary action of a sofic random subgroup of the free group

abstract:
  We prove that the boundary action of a sofic random subgroup of a finitely
generated free group is conservative. This addresses a question asked by
Grigorchuk, Kaimanovich, and Nagnibeda, who studied the boundary actions of
individual subgroups of the free group. Following their work, we also
investigate the cogrowth and various limit sets associated to sofic random
subgroups. We make heavy use of the correspondence between subgroups and their
Schreier graphs, and central to our approach is an investigation of the
asymptotic density of a given set inside of large neighborhoods of the root of
a sofic random Schreier graph.


title: Geometry of Wachspress surfaces

abstract:
  Let P_d be a convex polygon with d vertices. The associated Wachspress
surface W_d is a fundamental object in approximation theory, defined as the
image of the rational map w_d from P^2 to P^{d-1}, determined by the Wachspress
barycentric coordinates for P_d. We show w_d is a regular map on a blowup X_d
of P^2, and if d>4 is given by a very ample divisor on X_d, so has a smooth
image W_d. We determine generators for the ideal of W_d, and prove that in
graded lex order, the initial ideal of I(W_d) is given by a Stanley-Reisner
ideal. As a consequence, we show that the associated surface is arithmetically
Cohen-Macaulay, of Castelnuovo-Mumford regularity two, and determine all the
graded betti numbers of I(W_d).


title:
PlanetPack: a radial-velocity time-series analysis tool facilitating
  exoplanets detection, characterization, and dynamical simulations

abstract:
  We present PlanetPack, a new software tool that we developed to facilitate
and standardize the advanced analysis of radial velocity (RV) data for the goal
of exoplanets detection, characterization, and basic dynamical $N$-body
simulations. PlanetPack is a command-line interpreter, that can run either in
an interactive mode or in a batch mode of automatic script interpretation.
  Its major abilities include: (i) Advanced RV curve fitting with the proper
maximum-likelihood treatment of unknown RV jitter; (ii) User-friendly
multi-Keplerian as well as Newtonian $N$-body RV fits; (iii) Use of more
efficient maximum-likelihood periodograms that involve the full multi-planet
fitting (sometimes called as ``residual'' or ``recursive'' periodograms); (iv)
Easily calculatable parametric 2D likelihood function level contours,
reflecting the asymptotic confidence regions; (v) Fitting under some useful
functional constraints is user-friendly; (vi) Basic tasks of short- and
long-term planetary dynamical simulation using a fast Everhart-type integrator
based on Gauss--Legendre spacings; (vii) Fitting the data with red noise
(auto-correlated errors); (viii) Various analytical and numerical methods for
the tasks of determining the statistical significance.
  It is planned that further functionality may be added to PlanetPack in the
future. During the development of this software, a lot of effort was made to
improve the calculational speed, especially for CPU-demanding tasks. PlanetPack
was written in pure C++ (standard of 1998/2003), and is expected to be
compilable and usable on a wide range of platforms.


title: Semigroups and one-way functions

abstract:
  We study the complexity classes P and NP through a semigroup fP
("polynomial-time functions"), consisting of all polynomially balanced
polynomial-time computable partial functions. Then P is not equal to NP iff fP
is a non-regular semigroup. The one-way functions considered here are based on
worst-case complexity (they are not cryptographic); they are the non-regular
elements of fP. We prove various properties of fP, e.g., that it is finitely
generated. We define reductions with respect to which certain universal one-way
functions are fP-complete.


title:
I am 4 vho: new approach to improve seamless vertical hanover in
  heterogeneous wireless networks

abstract:
  Two mechanisms have been proposed independently by IEEE and 3GPP; namely,
Media Independent Handover (MIH) and Access Network Discovery and Selection
Function (ANDSF), respectively. These mechanisms enable a seamless Vertical
Handover (VHO) between the different types of technologies (3GPP and non-3GPP),
such as GSM (Global System for Mobile Communication), Wireless Fidelity (Wi-
Fi), Worldwide Interoperability for Microwave Access (WiMAX), Universal Mobile
Telecommunications System (UMTS) and Long Term Evolution (LTE). In this paper,
we overview these mechanisms and show their components, benefits and drawbacks.
Then we present our Imperative Alternative MIH for Vertical Handover (I AM 4
VHO) approach based on the approaches that have been studied in the literature
with better performance (packet loss and latency), less connection failure
(probability of reject sessions), less complexity and more exhaustive for
enhancing VHO heterogeneous wireless networks environment.


title:
Local well-posedness and wave breaking results for periodic solutions of
  a shallow water equation for waves of moderate amplitude

abstract:
  We study the local well-posedness of a periodic nonlinear equation for
surface waves of moderate amplitude in shallow water. We use an approach due to
Kato which is based on semigroup theory for quasi-linear equations. We also
show that singularities for the model equation can occur only in the form of
wave breaking, in particular surging breakers.


title:
Radiation of de-excited electrons at large times in a strong
  electromagnetic plane wave

abstract:
  The late time asymptotics of the physical solutions to the Lorentz-Dirac
equation in the electromagnetic external fields of simple configurations -- the
constant homogeneous field, the linearly polarized plane wave (in particular,
the constant uniform crossed field), and the circularly polarized plane wave --
are found. The solutions to the Landau-Lifshitz equation for the external
electromagnetic fields admitting a two-parametric symmetry group, which include
as a particular case the above mentioned field configurations, are obtained.
General properties of the total radiation power of a charged particle are
established. In particular, for a circularly polarized wave and constant
uniform crossed fields, the total radiation power in the asymptotic regime is
independent of the charge and the external field strength, when expressed in
terms of the proper-time, and equals a half of the rest energy of a charged
particle divided by its proper-time. The spectral densities of the radiation
power formed on the late time asymptotics are derived for a charged particle
moving in the external electromagnetic fields of the simple configurations
pointed above.


title:
Spectroscopic characterization of magnetoplasmonic nanodisk array: size,
  shape and lattice constant

abstract:
  Magneto optical activity implemented in plasmonic nanostructures provides a
new functionality in active plasmonics. To what an extent, one can benefit from
this new degree of freedom is still under open discussion. In this work, with
the development of a wavelength parallel characterization tool for measuring
the optic and MO properties of nanostructures, we present systematic studies of
the magneto-optical activity of Au/[Co/Pt]n/Au nanodisk array with various of
disk size, shape and grating constant.

categories: physics.optics cond-mat.mes-hall cond-mat.mtrl-sci physics.ins-det


title: Estimation of the finite right endpoint in the Gumbel domain

abstract:
  A simple estimator for the finite right endpoint of a distribution function
in the Gumbel max-domain of attraction is proposed. Large sample properties
such as consistency and the asymptotic distribution are derived. A simulation
study is also presented.


title: The Ehrenfest picture and the geometry of Quantum Mechanics

abstract:
  In this paper we develop a picture of Quantum Mechanics based on the
description of physical observables in terms of expectation value functions,
generalizing thus the so called Ehrenfest theorems for quantum dynamics. Our
basic technical ingredient is the set of tools which has been developed in the
last years for the geometrical formulation of Quantum Mechanics. In the new
picture, we analyze the problem of the dynamical equations, the uncertainty
relations and interference and illustrate the construction with the simple case
of a two-level system.


title:
Sizing Optimization of Truss Structures using a Hybridized Genetic
  Algorithm

abstract:
  This paper presents a genetic-based hybrid algorithm that combines the
exploration power of Genetic Algorithm (GA) with the exploitation capacity of a
phenotypical probabilistic local search algorithm. Though not limited to a
certain class of optimization problems, the proposed algorithm has been
"fine-tuned" to work particularly efficiently on the optimal design of planar
and space structures, a class of problems characterized by the large number of
design variables and constraints, high degree of non-linearity and multitude of
local minima. The proposed algorithm has been applied to the skeletal weight
reduction of various planar and spatial trusses and shown to be superior in all
of the cases,


title:
Alfven Wave Collisions, The Fundamental Building Block of Plasma
  Turbulence I: Asymptotic Solution

abstract:
  The nonlinear interaction between counterpropagating Alfven waves is the
physical mechanism underlying the cascade of energy to small scales in
astrophysical plasma turbulence. Beginning with the equations for
incompressible MHD, an asymptotic analytical solution for the nonlinear
evolution of these Alfven wave collisions is derived in the weakly nonlinear
limit. The resulting qualitative picture of nonlinear energy transfer due to
this mechanism involves two steps: first, the primary counterpropagating Alfven
waves interact to generate an inherently nonlinear, purely magnetic secondary
fluctuation with no parallel variation; second, the two primary waves each
interact with this secondary fluctuation to transfer energy secularly to two
tertiary Alfven waves. These tertiary modes are linear Alfven waves with the
same parallel wavenumber as the primary waves, indicating the lack of a
parallel cascade. The amplitude of these tertiary modes increases linearly with
time due to the coherent nature of the resonant four-wave interaction
responsible for the nonlinear energy transfer. The implications of this
analytical solution for turbulence in astrophysical plasmas is discussed. The
solution presented here provides valuable intuition about the nonlinear
interactions underlying magnetized plasma turbulence, in support of an
experimental program to verify in the laboratory the nature of this fundamental
building block of astrophysical plasma turbulence.


title:
Alfven Wave Collisions, The Fundamental Building Block of Plasma
  Turbulence II: Numerical Solution

abstract:
  This paper presents the numerical verification of an asymptotic analytical
solution for the nonlinear interaction between counterpropagating Alfven waves,
the fundamental building block of astrophysical plasma turbulence. The
analytical solution, derived in the weak turbulence limit using the equations
of incompressible MHD, is compared to a nonlinear gyrokinetic simulation of an
Alfven wave collision. The agreement between these methods signifies that the
incompressible solution satisfactorily describes the essential dynamics of the
nonlinear energy transfer, even under the weakly collisional plasma conditions
relevant to many astrophysical environments.


title: About one generalisation of the Leibniz theorem

abstract:
  The well-known Leibniz theorem (Leibniz Criterion or alternating series test)
of convergence of alternating series is generalized for the case when the
absolute value of terms of series are "not absolutely monotonously" convergent
to zero. Questions of accuracy of the estimation for the series remainder are
considered.


title:
Modified Euler approximation scheme for stochastic differential
  equations driven by fractional Brownian motions

abstract:
  For a stochastic differential equation driven by a fractional Brownian motion
with Hurst parameter $H> \frac12$ it is known that the classical Euler scheme
has the rate of convergence $2H-1$. In this paper we introduce a new numerical
scheme which is closer to the classical Euler scheme for diffusion processes,
in the sense that it has the rate of convergence $2H-\frac12$. In particular,
the rate of convergence becomes $\frac 12$ when $H$ is formally set to $\frac
12$ (the rate of Euler scheme for classical Brownian motion). The rate of weak
convergence is also deduced for this scheme. The main tools are fractional
calculus and Malliavin calculus. We also apply our approach to the classical
Euler scheme.


title: On the category of weak bialgebras

abstract:
  Weak (Hopf) bialgebras are described as (Hopf) bimonoids in appropriate
duoidal (also known as 2-monoidal) categories. This interpretation is used to
define a category wba of weak bialgebras over a given field. As an application,
the "free vector space" functor from the category of small categories with
finitely many objects to wba is shown to possess a right adjoint, given by
taking (certain) group-like elements. This adjunction is proven to restrict to
the full subcategories of groupoids and of weak Hopf algebras, respectively. As
a corollary, we obtain equivalences between the category of small categories
with finitely many objects and the category of pointed cosemisimple weak
bialgebras; and between the category of small groupoids with finitely many
objects and the category of pointed cosemisimple weak Hopf algebras.


title:
Alfven Wave Collisions, The Fundamental Building Block of Plasma
  Turbulence III: Theory for Experimental Design

abstract:
  Turbulence in space and astrophysical plasmas is governed by the nonlinear
interactions between counterpropagating Alfven waves. Here we present the
theoretical considerations behind the design of the first laboratory
measurement of an Alfven wave collision, the fundamental interaction underlying
Alfvenic turbulence. By interacting a relatively large-amplitude, low-frequency
Alfven wave with a counterpropagating, smaller-amplitude, higher-frequency
Alfven wave, the experiment accomplishes the secular nonlinear transfer of
energy to a propagating daughter Alfven wave. The predicted properties of the
nonlinearly generated daughter Alfven wave are outlined, providing a suite of
tests that can be used to confirm the successful measurement of the nonlinear
interaction between counterpropagating Alfven waves in the laboratory.


title:
The GTZAN dataset: Its contents, its faults, their effects on
  evaluation, and its future use

abstract:
  The GTZAN dataset appears in at least 100 published works, and is the
most-used public dataset for evaluation in machine listening research for music
genre recognition (MGR). Our recent work, however, shows GTZAN has several
faults (repetitions, mislabelings, and distortions), which challenge the
interpretability of any result derived using it. In this article, we disprove
the claims that all MGR systems are affected in the same ways by these faults,
and that the performances of MGR systems in GTZAN are still meaningfully
comparable since they all face the same faults. We identify and analyze the
contents of GTZAN, and provide a catalog of its faults. We review how GTZAN has
been used in MGR research, and find few indications that its faults have been
known and considered. Finally, we rigorously study the effects of its faults on
evaluating five different MGR systems. The lesson is not to banish GTZAN, but
to use it with consideration of its contents.


title:
K-Algorithm A Modified Technique for Noise Removal in Handwritten
  Documents

abstract:
  OCR has been an active research area since last few decades. OCR performs the
recognition of the text in the scanned document image and converts it into
editable form. The OCR process can have several stages like pre-processing,
segmentation, recognition and post processing. The pre-processing stage is a
crucial stage for the success of OCR, which mainly deals with noise removal. In
the present paper, a modified technique for noise removal named as K-Algorithm
has been proposed, which has two stages as filtering and binarization. The
proposed technique shows improvised results in comparison to median filtering
technique.


title:
For finite n\geq 3, and k\geq 4, the variety SNr_n\CA_{n+k} is not atom
  canonical

abstract:
  We show that there exists an atomic representable polyadic equality algebra
of finite dimension n\geq 3, such that the cylindric reduct of its completion
is not in SNr_n\CA_{n+4}, hence the result in the title. This solves an open
problem in algebraic logic, though the values for k=n+1, n+2, n+3, is still, to
the best of our knowlege unknown.


title:
A polyadic algebra of infinite dimension is completely representable if
  and only if it is atomic and completely additive

abstract:
  We prove the result in the title. We infer, that unlike cylindric algebras,
there is a first order axiomatization of the class of completely representable
polyadic algebras of infinite dimension, though the one we obtain is infinite;
in fact uncountable, but shares a single schema, stipulating that the
(uncountably many)substitution operators are completely additive. Similar
results are obtained for non commutative reducts of polyadic equality algebras
of infinite dimensions, where we can drop complete additivity. However, it
remains unknown to us whether there are atomic polyadic algebras of infinite
dimension that are not completely additive; but we strongly conjecture that
there are.


title: The uniqueness of the Fisher metric as information metric

abstract:
  We define a mixed topology on the fiber space $\cup_\mu \oplus^n L^n(\mu)$
over the space $\mathcal{M}(\Omega)$ of all finite non-negative measures $\mu$
on a separable metric space $\Omega$ provided with Borel $\sigma$-algebra. We
define a notion of strong continuity of a covariant $n$-tensor field on
$\mathcal{M}(\Omega)$. Under the assumption of strong continuity of an
information metric we prove the uniqueness of the Fisher metric as information
metric on statistical models associated with $\Omega$. Our proof realizes a
suggestion due to Amari and Nagaoka to derive the uniqueness of the Fisher
metric from the special case proved by Chentsov by using a special kind of
limiting procedure. The obtained result extends the monotonicity
characterization of the Fisher metric on statistical models associated with
finite sample spaces and complement the uniqueness theorem by
Ay-Jost-L\^e-Schwachh\"ofer that characterizes the Fisher metric by its
invariance under sufficient statistics.


title: Weak multiplier bialgebras

abstract:
  A non-unital generalization of weak bialgebra is proposed with a
multiplier-valued comultiplication. Certain canonical subalgebras of the
multiplier algebra (named the `base algebras') are shown to carry coseparable
co-Frobenius coalgebra structures. Appropriate modules over a weak multiplier
bialgebra are shown to constitute a monoidal category via the (co)module tensor
product over the base algebra. The relation to Van Daele and Wang's (regular
and arbitrary) weak multiplier Hopf algebra is discussed.


title:
Highly Scalable, Parallel and Distributed AdaBoost Algorithm using Light
  Weight Threads and Web Services on a Network of Multi-Core Machines

abstract:
  AdaBoost is an important algorithm in machine learning and is being widely
used in object detection. AdaBoost works by iteratively selecting the best
amongst weak classifiers, and then combines several weak classifiers to obtain
a strong classifier. Even though AdaBoost has proven to be very effective, its
learning execution time can be quite large depending upon the application e.g.,
in face detection, the learning time can be several days. Due to its increasing
use in computer vision applications, the learning time needs to be drastically
reduced so that an adaptive near real time object detection system can be
incorporated. In this paper, we develop a hybrid parallel and distributed
AdaBoost algorithm that exploits the multiple cores in a CPU via light weight
threads, and also uses multiple machines via a web service software
architecture to achieve high scalability. We present a novel hierarchical web
services based distributed architecture and achieve nearly linear speedup up to
the number of processors available to us. In comparison with the previously
published work, which used a single level master-slave parallel and distributed
implementation [1] and only achieved a speedup of 2.66 on four nodes, we
achieve a speedup of 95.1 on 31 workstations each having a quad-core processor,
resulting in a learning time of only 4.8 seconds per feature.


title: Topological dynamics and recognition of languages

abstract:
  We define compact automata and show that every language has a unique minimal
compact automaton. We also define recognition of languages by compact left
semitopological monoids and construct the analogue of the syntactic monoid in
this context. For rational languages this reduces to the usual theory of finite
automata and finite monoids.


title:
A model driven engineering approach to develop a cooperative information
  system

abstract:
  To reuse one or several existing systems in order to develop a complex system
is a common practice in software engineering. This approach can be justified by
the fact that it is often difficult for a single Information System (IS) to
accomplish all the requested tasks. So, one solution is to combine many
different ISs and make them collaborate in order to realize these tasks. We
proposed an approach named AspeCiS (An Aspect-oriented Approach to Develop a
Cooperative Information System) to develop a Cooperative Information System
from existing ISs by using their artifacts such as existing requirements, and
design. AspeCiS covers the three following phases: (i) discovery and analysis
of Cooperative Requirements, (ii) design of Cooperative Requirements models,
and (iii) preparation of the implementation phase. The main issue of AspeCiS is
the definition of Cooperative Requirements using the Existing Requirements and
Additional Requirements, which should be composed with Aspectual Requirements.
We earlier studied how to elicit the Cooperative Requirements in AspeCiS (phase
of discovery and analysis of Cooperative Requirements in AspeCiS) . We study
here the second phase of AspeCiS (design of Cooperative Requirements models),
by the way of a model weaving process. This process uses so-called AspeCiS
Weaving Metamodel, and it weaves Existing and Additional Requirements models to
realize Cooperative Requirements models.


title: Two-colour generation in a chirped seeded Free-Electron Laser

abstract:
  We present the experimental demonstration of a method for generating two
spectrally and temporally separated pulses by an externally seeded, single-pass
free-electron laser operating in the extreme-ultraviolet spectral range. Our
results, collected on the FERMI@Elettra facility and confirmed by numerical
simulations, demonstrate the possibility of controlling both the spectral and
temporal features of the generated pulses. A free-electron laser operated in
this mode becomes a suitable light source for jitter-free, two-colour
pump-probe experiments.


title: On the origin of the giant SHE in Cu(Bi) alloys

abstract:
  Two years after the prediction of a giant spin Hall effect for the dilute
Cu(Bi) alloy [Gradhand et al., Phys. Rev. B 81, 245109 (2010)], a comparably
strong effect was measured in thin films of Cu(Bi) alloys by Niimi et al.
[Phys. Rev. Lett. 109, 156602 (2012)]. Both theory and experiment consider the
skew-scattering mechanism to be responsible, however they obtain opposite sign
for the spin Hall angle. Based on a detailed analysis of existing theoretical
results, we explore differences between theory and experiment.


title: Work and energy gain of heat-pumped quantized amplifiers

abstract:
  We investigate heat-pumped single-mode amplifiers of quantized fields in
high-Q cavities based on non-inverted two-level systems. Their power generation
is shown to crucially depend on the capacity of the quantum state of the field
to accumulate useful work. By contrast, the energy gain of the field is shown
to be insensitive to its quantum state. Analogies and differences with masers
are explored.


title:
On the Non-Self-adjoint Sturm-Liouville Operators in the Space of
  Vector-Functions

abstract:
  In this article we obtain asymptotic formulas for the eigenvalues and
eigenfunctions of the non-self-adjoint operator generated in space of
vector-functions by the Sturm-Liouville equation with m by m matrix potential
and the boundary conditions whose scalar case (m=1) are strongly regular. Using
these asymptotic formulas, we find a condition on the potential for which the
root functions of this operator form a Riesz basis.


title:
Electronic excitations of magnetic impurity state in diluted magnetic
  semiconductor (Ga,Mn)As

abstract:
  The electronic structure of doped Mn in (Ga,Mn)As is studied by resonant
inelastic X-ray scattering (RIXS). From configuration-interaction cluster-model
calculations, the line shapes of the Mn $L_3$ RIXS spectra can be explained by
$d$-$d$ excitations from the Mn$^{3+}$ ground state, dominated by
charge-transferred states, rather than a Mn$^{2+}$ ground state. Unlike
archetypical $d$-$d$ excitation, the peak widths are broader than the
experimental energy resolution. We attribute the broadening to a finite
lifetime of the $d$-$d$ excitations, which decay rapidly to electron-hole pairs
in the host valence and conduction bands through hybridization of the Mn $3d$
orbital with the ligand band.


title:
Measurement and Analysis of Radio-frequency Radiation Exposure Level
  from Different Mobile Base Transceiver Stations in Ajaokuta and Environs,
  Nigeria

abstract:
  We present the result of a preliminary assessment of radio-frequency
radiation exposure from selected mobile base stations in Ajaokuta environs. The
Power density of RF radiation within a radial distance of 125m was measured.
Although values fluctuated due to the influence of other factors, including
wave interference from other electromagnetic sources around reference base
stations, we show from analysis that radiation exposure level is below the
standard limit (4.5W/sqm for 900MHz and 9W/sqm for 18000MHz) set by the
International Commission on Non-ionizing Radiation Protection (ICNIRP) and
other regulatory agencies.


title: On one-point functions for sinh-Gordon model at finite temperature

abstract:
  Using fermionic basis we conjecture the exact formulae for the expectation
values of local fields in sinh-Gordon model. The conjecture is checked against
previously known results.


title: Planar 4-critical graphs with four triangles

abstract:
  By the Grunbaum-Aksenov Theorem (extending Grotzsch's Theorem) every planar
graph with at most three triangles is 3-colorable. However, there are
infinitely many planar 4-critical graphs with exactly four triangles. We
describe all such graphs. This answers a question of Erdos from 1990.


title:
Agents and owl-s based semantic web service discovery with user
  preference support

abstract:
  Service-oriented computing (SOC) is an interdisciplinary paradigm that
revolutionizes the very fabric of distributed software development applications
that adopt service-oriented architectures (SOA) can evolve during their
lifespan and adapt to changing or unpredictable environments more easily. SOA
is built around the concept of Web Services. Although the Web services
constitute a revolution in Word Wide Web, they are always regarded as
non-autonomous entities and can be exploited only after their discovery. With
the help of software agents, Web services are becoming more efficient and more
dynamic. The topic of this paper is the development of an agent based approach
for Web services discovery and selection in witch, OWL-S is used to describe
Web services, QoS and service customer request. We develop an efficient
semantic service matching which takes into account concepts properties to match
concepts in Web service and service customer request descriptions. Our approach
is based on an architecture composed of four layers: Web service and Request
description layer, Functional match layer, QoS computing layer and Reputation
computing layer.


title: Adapted random perturbations for non-uniformly expanding maps

abstract:
  We obtain stochastic stability of C2 non-uniformly expanding one-dimensional
endomorphisms, requiring only that the first hyperbolic time map be
L^{p}-integrable for p>3. We show that, under this condition (which depends
only on the unperturbed dynamics), we can construct a random perturbation that
preserves the original hyperbolic times of the unperturbed map and, therefore,
to obtain non-uniform expansion for random orbits. This ensures that the first
hyperbolic time map is uniformly integrable for all small enough noise levels,
which is known to imply stochastic stability. The method enables us to obtain
stochastic stability for a class of maps with infinitely many critical points.
For higher dimensional endomorphisms, a similar result is obtained, but under
stronger assumptions.


title: On the isomorphisms of Fourier algebras of finite abelian groups

abstract:
  We consider gerenalizated permutation equivalence of Vielenkin system on
commutative compact torsion finite exponent groups.


title:
The Effect of the Pre-Detonation Stellar Internal Velocity Profile on
  the Nucleosynthetic Yields in Type Ia Supernova

abstract:
  A common model of the explosion mechanism of Type Ia supernovae is based on a
delayed detonation of a white dwarf. A variety of models differ primarily in
the method by which the deflagration leads to a detonation. A common feature of
the models, however, is that all of them involve the propagation of the
detonation through a white dwarf that is either expanding or contracting, where
the stellar internal velocity profile depends on both time and space. In this
work, we investigate the effects of the pre-detonation stellar internal
velocity profile and the post-detonation velocity of expansion on the
production of alpha-particle nuclei, including Ni56, which are the primary
nuclei produced by the detonation wave. We perform one-dimensional hydrodynamic
simulations of the explosion phase of the white dwarf for center and off-center
detonations with five different stellar velocity profiles at the onset of the
detonation. We observe two distinct post-detonation expansion phases:
rarefaction and bulk expansion. Almost all the burning to Ni56 occurs only in
the rarefaction phase, and its expansion time scale is influenced by
pre-existing flow structure in the star, in particular by the pre-detonation
stellar velocity profile. We find that the mass fractions of the alpha-particle
nuclei, including Ni56, are tight functions of the empirical physical parameter
rho_up/v_down, where rho_up is the mass density immediately upstream of the
detonation wave front and v_down is the velocity of the flow immediately
downstream of the detonation wave front. We also find that v_down depends on
the pre-detonation flow velocity. We conclude that the properties of the
pre-existing flow, in particular the internal stellar velocity profile,
influence the final isotopic composition of burned matter produced by the
detonation.


title: Topics in Nuclear Structure

abstract:
  We consider work performed over the last decade on single-j-shell studies. We
will discuss four topics.


title: Superabsorption of light via quantum engineering

abstract:
  Almost 60 years ago Dicke introduced the term superradiance to describe a
signature quantum effect: N atoms can collectively emit light at a rate
proportional to N^2. Even for moderate N this represents a significant increase
over the prediction of classical physics, and the effect has found applications
ranging from probing exciton delocalisation in biological systems, to
developing a new class of laser, and even in astrophysics. Structures that
super-radiate must also have enhanced absorption, but the former always
dominates in natural systems. Here we show that modern quantum control
techniques can overcome this restriction. Our theory establishes that
superabsorption can be achieved and sustained in certain simple nanostructures,
by trapping the system in a highly excited state while extracting energy into a
non-radiative channel. The effect offers the prospect of a new class of quantum
nanotechnology, capable of absorbing light many times faster than is currently
possible; potential applications of this effect include light harvesting and
photon detection. An array of quantum dots or a porphyrin ring could provide an
implementation to demonstrate this effect.


title: Modified logarithmic Sobolev inequalities for canonical ensembles

abstract:
  In this paper, we prove modified logarithmic Sobolev inequalities for
canonical ensembles with superquadratic single-site potential. These
inequalities were introduced by Bobkov and Ledoux, and are closely related to
concentration of measure and transport-entropy inequalities. Our method is an
adaptation of the iterated two-scale approach that was developed by Menz and
Otto to prove the usual logarithmic Sobolev inequality in this context. As a
consequence, we obtain convergence in Wasserstein distance $W_p$ for Kawasaki
dynamics on the Ginzburg-Landau model.


title:
HBT interferometry relative to the triangular flow plane in heavy-ion
  collisions

abstract:
  The PHENIX Collaboration has reported third-order harmonic oscillations of
the source radius parameters when measuring the Hanbury Brown-Twiss correlation
function for charged hadrons relative to the triangular flow angle. We explore
possible origins of such third-order oscillations with a simple Gaussian source
featuring both a triangular geometric deformation and triangular flow.
Third-order oscillations of the HBT radii can arise from a purely geometric
triangular deformation superimposed on an azimuthally symmetric radial flow, or
from a radially symmetry spatial distribution which expands anisotropically
with a triangular component in the flow velocity profile. In both cases the
final particle momentum distribution features triangular flow. We show that the
two alternatives can be distinguished experimentally through the phase of the
azimuthal oscillations of the HBT radii relative to the triangular flow plane.


title:
Strong Structural Controllability and Observability of Linear
  Time-Varying Systems

abstract:
  In this note we consider continuous-time systems x'(t) = A(t) x(t) + B(t)
u(t), y(t) = C(t) x(t) + D(t) u(t), as well as discrete-time systems x(t+1) =
A(t) x(t) + B(t) u(t), y(t) = C(t) x(t) + D(t) u(t) whose coefficient matrices
A, B, C and D are not exactly known. More precisely, all that is known about
the systems is their nonzero pattern, i.e., the locations of the nonzero
entries in the coefficient matrices. We characterize the patterns that
guarantee controllability and observability, respectively, for all choices of
nonzero time functions at the matrix positions defined by the pattern, which
extends a result by Mayeda and Yamada for time-invariant systems. As it turns
out, the conditions on the patterns for time-invariant and for time-varying
discrete-time systems coincide, provided that the underlying time interval is
sufficiently long. In contrast, the conditions for time-varying continuous-time
systems are more restrictive than in the time-invariant case.


title: Gauge-Stringy Instantons in N=2 U(N) Gauge Theories

abstract:
  Using D3/D(-1) brane set-up in type IIB string theory we introduce
gauge-stringy instantons in N=2 U(N) supersymmetry theories with one matter
multiplet in symmetric representation. In addition to the gauge and stringy
moduli there exist extra zero modes that we refer to as "gauge-stringy" moduli.
We show that the measure of the moduli space in this model becomes
dimensionless for arbitary N when the gauge instanton charge k_g is equal to
the stringy instanton charge k_s. This property of gauge-stringy instantons
leads to having equal contributions from all instanton charges k_s=k_g=k in the
effective action. We derive the gauge-stringy instanton partition function and
calculate the corrections to the prepotential due to k=1,2 gauge-stringy
instanton charges. As a by-product the partition function for gauge k-instanton
is obtained which coincides with the result from the standard ADHM
construction.


title: A new method for estimating the bolometric properties of Ibc SNe

abstract:
  The bolometric properties (nickel mass, ejecta mass and kinetic energies) of
61 Ibc supernovae (SNe), including 20 Gamma-Ray Burst and X-Ray Flash
(GRB/XRF), 19 Ib, 13 Ic and 9 Ic-BL (broad-lined) SNe are presented. All of the
available $BVRI$ photometry in the literature have been collected and used in a
new method that utilizes a template supernova (SN 1998bw) and an analytical
model based on Arnett (1982) to accurately estimate the bolometric properties
of each SN. A statistical analysis of the bolometric properties is then
performed, where it is found that GRB/XRF SNe are the most energetic, and eject
more mass (including nickel content) than Ib, Ic and Ic-BL SNe. The results are
then compared to the existing progenitor models of Ibc SNe, where it is
concluded that it is highly likely that at least two progenitor channels exist
for producing a Ibc SN: most Ibc SNe arise via binary interactions, where the
mass of the stellar progenitor is less than what is attributed to a Wolf Rayet
star. Conversely, the progenitors of Ic-BL and GRB/XRF are more massive than
those of Ib and Ic SNe, though a key difference between them is progenitor
metallicity, with Ic-BL SNe arise from more metal rich progenitors. As mass
loss in massive stars is influenced by metal content, the progenitors of Ic-BL
SNe lose more mass, and therefore more angular momentum, before exploding. It
is expected that the explosion mechanism in Ic-BL and GRB/XRF SNe is
``engine-driven'' (i.e. an accreting black hole, or a millisecond magnetar),
but the increased mass loss of Ic-BL SNe means the central engine is less
powerful than in GRB/XRF SNe. Finally, it is found that the SNe that accompany
GRBs and XRFs are statistically indistinguishable, and some mechanism other
than metallicity is needed to explain the differences in the high-energy
components in these events.


title: Affine group formulation of the Standard Model coupled to gravity

abstract:
  This work demonstrates that a complete description of the interaction of
matter and all forces, gravitational and non-gravitational, can in fact be
realized within a quantum affine algebraic framework. Using the affine group
formalism, we construct elements of a physical Hilbert space for full,
Lorentzian quantum gravity coupled to the Standard Model in four spacetime
dimensions. Affine algebraic quantization of gravitation and matter on equal
footing implies a fundamental uncertainty relation which is predicated upon a
non-vanishing cosmological constant.


title: Managing Knowledge to Enhance Learning

abstract:
  The article first summarizes reasons why current approaches supporting Open
Learning and Distance Education need to be complemented by tools permitting
lecturers, researchers and students to cooperatively organize the semantic
content of Learning related materials (courses, discussions, etc.) into a
fine-grained shared semantic network. This first part of the article also
quickly describes the approach adopted to permit such a collaborative work.
Then, examples of such semantic networks are presented. Finally, an evaluation
of the approach by students is provided and analyzed.