title: Towards Minimizing k-Submodular Functions

abstract:
  In this paper we investigate k-submodular functions. This natural family of
discrete functions includes submodular and bisubmodular functions as the
special cases k = 1 and k = 2 respectively.
  In particular we generalize the known Min-Max-Theorem for submodular and
bisubmodular functions. This theorem asserts that the minimum of the
(bi)submodular function can be found by solving a maximization problem over a
(bi)submodular polyhedron. We define and investigate a k-submodular polyhedron
and prove a Min-Max-Theorem for k-submodular functions.


title:
Super-Critical and Sub-Critical Hopf bifurcations in two and three
  dimensions

abstract:
  Hopf bifurcations have been studied perturbatively under two broad headings,
viz., super-critical and sub-critical. The criteria for occurrences of such
bifurcations have been investigated using the renormalization group. The
procedure has been described in details for both two and three dimensions and
has been applied to several important models, including those by Lorenz and
Rossler.


title:
Scattering Amplitudes for Multi-indexed Extensions of Solvable
  Potentials

abstract:
  New solvable one-dimensional quantum mechanical scattering problems are
presented. They are obtained from known solvable potentials by multiple Darboux
transformations in terms of virtual and pseudo virtual wavefunctions. The same
method applied to confining potentials, e.g. P\"oschl-Teller and the radial
oscillator potentials, has generated the {\em multi-indexed Jacobi and Laguerre
polynomials}. Simple multi-indexed formulas are derived for the transmission
and reflection amplitudes of several solvable potentials.

categories: quant-ph hep-th math-ph math.MP math.SP nlin.SI


title: Ground state of the spin-1/2 chain of green dioptase at high fields

abstract:
  The gem-stone dioptase Cu6Si6O18.6H2O has a chiral crystal structure of
equilateral triangular helices consisting of Cu-3d spins. It shows an
antiferromagnetic order with an easy axis along c at TN = 15.5 K under zero
field, and a magnetization jump at HC = 13.5 T when the field is applied along
c-axis. By 29Si-NMR measurements, we have revealed that the high-field state is
essentially the two sub-lattice structure, and that the component within
ab-plane is collinear. The result indicates no apparent match with the
geometrical pattern of helical spin chain.


title: Ground state of the competing spin chain Cs2Cu2Mo3O12

abstract:
  The high-field ground state of the competing-spin-chain compound Cs2Cu2Mo3O12
with the ferromagnetic first-nearest-neighbor J1=-93 K and the
antiferromagnetic second-nearest-neighbor J2 = +33 K was investigated by
133Cs-NMR. A divergence of T1-1 and a peak-splitting in spectra were observed
at TN = 1.85 K, indicating the existence of a field-induced long range magnetic
order. In the paramagnetic region above 4 K, T1-1 showed a power-law
temperature dependence T2K-1. The exponent K was strongly field-dependent,
suggesting the possibility of the spin-nematic Tomonaga Luttinger Liquid state.


title:
Effect of Elastic Vibrations on Normal Head on Collisions of Isothermal
  Spheres

abstract:
  We numerically investigate head on collisions of isothermal visco-elastic
spheres. We find that the restitution coefficient oscillates against the impact
speed if the solid viscosity inside the sphere is small enough. We confirm that
the oscillation arises from the resonance between the duration of contact and
the eigen-frequencies of the sphere. This oscillation disappears if there
exists the strong solid viscosity in spheres. We also find that a sinusoidal
behavior of the restitution coefficient against the initial phase in the
eigenmodes for collisions between a thermally activated sphere and a flat wall.
As a result, the restitution coefficient can exceed unity if the impact speed
of the colliding sphere is nearly equal to or slower than the thermal speed. We
have confirmed the existence of the fluctuation theorem for impact processes
through our simulation.


title: Sobolev functions on infinite-dimensional domains

abstract:
  We study extensions of Sobolev and BV functions on infinite-dimensional
domains. Along with some positive results we present a negative solution of the
long-standing problem of existence of Sobolev extensions of functions in
Gaussian Sobolev spaces from a convex domain to the whole space.


title:
Efficiency of electrical manipulation on two-dimensional topological
  insulators

abstract:
  We investigate the efficiency of electrical manipulation on two-dimensional
topological insulators by considering a lateral potential superlattice on the
system. The electronic states under various conditions are examined carefully.
It is found that the dispersion of the mini-band and the electron distribution
in the potential well region display an oscillatory behavior as the potential
strength of the lateral superlattice increases. The probability of finding an
electron in the potential well region can be larger or smaller than the average
as the potential strength varies. This indicates that the electric manipulation
efficiency on two-dimensional topological insulators is not as high as
expected, which should be carefully considered in designing a device
application that bases on two-dimensional topological insulators. These
features can be attributed to the coupled multiple-band nature of the
topological insulator model. In addition, it is also found that these behaviors
are not sensitive to the gap parameter of the two-dimensional topological
insulator model.


title: Supernova neutrinos and nucleosynthesis

abstract:
  Observations of metal-poor stars indicate that at least two different
nucleosynthesis sites contribute to the production of r-process elements. One
site is responsible for the production of light r-process elements Z<~50 while
the other produces the heavy r-process elements. We have analyzed recent
observations of metal-poor stars selecting only stars that are enriched in
light r-process elements and poor in heavy r-process elements. We find a strong
correlation between the observed abundances of the N=50 elements (Sr, Y and Zr)
and Fe. It suggest that neutrino-driven winds from core-collapse supernova are
the main site for the production of these elements. We explore this possibility
by performing nucleosynthesis calculations based on long term Boltzmann
neutrino transport simulations. They are based on an Equation of State that
reproduces recent constrains on the nuclear symmetry energy. We predict that
the early ejecta is neutron-rich with Ye ~ 0.48, it becomes proton rich around
4 s and reaches Ye = 0.586 at 9 s when our simulation stops. The
nucleosynthesis in this model produces elements between Zn and Mo, including
92Mo. The elemental abundances are consistent with the observations of the
metal-poor star HD 12263. For the elements between Ge and Mo, we produce mainly
the neutron-deficient isotopes. This prediction can be confirmed by
observations of isotopic abundances in metal-poor stars. No elements heavier
than Mo (Z=42) and no heavy r-process elements are produced in our
calculations.


title: Fast $k$-NNG construction with GPU-based quick multi-select

abstract:
  In this paper we describe a new brute force algorithm for building the
$k$-Nearest Neighbor Graph ($k$-NNG). The $k$-NNG algorithm has many
applications in areas such as machine learning, bio-informatics, and clustering
analysis. While there are very efficient algorithms for data of low dimensions,
for high dimensional data the brute force search is the best algorithm. There
are two main parts to the algorithm: the first part is finding the distances
between the input vectors which may be formulated as a matrix multiplication
problem. The second is the selection of the $k$-NNs for each of the query
vectors. For the second part, we describe a novel graphics processing unit
(GPU) -based multi-select algorithm based on quick sort. Our optimization makes
clever use of warp voting functions available on the latest GPUs along with
use-controlled cache. Benchmarks show significant improvement over
state-of-the-art implementations of the $k$-NN search on GPUs.


title:
Higher-order Reverse Automatic Differentiation with emphasis on the
  third-order

abstract:
  It is commonly assumed that calculating third order information is too
expensive for most applications. But we show that the directional derivative of
the Hessian ($D^3f(x)\cdot d$) can be calculated at a cost proportional to that
of a state-of-the-art method for calculating the Hessian matrix. We do this by
first presenting a simple procedure for designing high order reverse methods
and applying it to deduce several methods including a reverse method that
calculates $D^3f(x)\cdot d$. We have implemented this method taking into
account symmetry and sparsity, and successfully calculated this derivative for
functions with a million variables. These results indicate that the use of
third order information in a general nonlinear solver, such as Halley-Chebyshev
methods, could be a practical alternative to Newton's method.


title:
Ground state of bond-disordered quasi-one-dimensional spin system
  (CH3)2CHNH3Cu(ClxBr1-x)3 with x = 0, 0.25 and 0.3

abstract:
  The ground state of the quasi-one-dimensional system with bond-disorder
(CH3)2CHNH3Cu(ClxBr1-x)3 with x = 0, 0.25 and 0.3 has been investigated by
muSR. The Fourier spectrum of electron spin fluctuation in x =0.25 and 0.3
obtained by LF-muSR technique shows that there exists a soft-mode toward a
possible phase transition to an exotic phase such as Bose-glass. In gapped
system with x = 0, the Fourier spectrum is totally different from the other
two, indicating the existence of the quantum critical point at a finite x
between 0 and 0.25.


title:
Phase transition to spatial Bloch-like oscillation in squeezed photonic
  lattices

abstract:
  We propose an exactly solvable waveguide lattice incorporating inhomogeneous
coupling coefficient. This structure provides a classical analogue to the
squeezed number and squeezed coherent intensity distribution in quantum optics
where the propagation length plays the role of squeezed amplitude. The
intensity pattern is obtained in a closed form for an arbitrary distribution of
the initial beam profile. We have also investigated the phase transition to the
spatial Bloch-like oscillations by adding a linear gradient to the propagation
constant of each waveguides ($ \alpha $). Our analytical results show that the
Bloch-like oscillations appear above a critical value for the linear gradient
of propagation constant ($ \alpha > \alpha_{c} $). The phase transition (in the
propagation properties of the waveguide) is a result of competition between
discrete and Bragg diffraction. Moreover, the light intensity decay
algebraically along each waveguide at the critical point while it falls off
exponentially below the critical point ($ \alpha < \alpha_{c} $).


title: Schrodinger Operators with Non-Symmetric Zero-Range Potentials

abstract:
  Non-self-adjoint Schrodinger operators A which correspond to non-symmetric
zero-range potentials are investigated. For a given A, the description of
non-real eigenvalues, spectral singularities and exceptional points are
obtained; the possibility of interpretation of A as a self-adjoint operator in
a Krein space is studied, the problem of similarity of A to a self-adjoint
operator in a Hilbert space is solved.


title: Electrostatic skeletons

abstract:
  Let u be the equilibrium potential of a compact set K. An electrostatic
skeleton of K is a positive measure whose closed support has connected
complement and no interior, and whose potential is equal to u near infinity. We
prove the existence of an electrostatic skeleton for any simplex.


title: Extension of continuous functions and weakly developable spaces

abstract:
  The aim of this paper is to investigate weakly developable spaces. For a
comparison with semi-metrizable spaces, we introduce and study a class of
spaces among those of weakly developable spaces, semimetrizable spaces and
first countable spaces having a G_delta-diagonal. Some results are obtained and
applications to the problem of extending continuous functions are discussed.


title:
Robust stationary mechanical squeezing in a kicked quadratic
  optomechanical system

abstract:
  We propose a scheme for the generation of a robust stationary squeezed state
of a mechanical resonator in a quadratically coupled optomechanical system,
driven by a pulsed laser. The intracavity photon number presents periodic
intense peaks suddenly stiffening the effective harmonic potential felt by the
mechanical resonator. These "optical spring kicks" tend to squeeze the
resonator position, and due to the interplay with fluctuation-dissipation
processes one can generate a stationary state with more than 13 dB of squeezing
even starting from moderately "pre-cooled" initial thermal states.


title: Logistic biplot for nominal data

abstract:
  Classical Biplot Methods allow for the simultaneous representation of
individuals (rows) and variables (columns) of a data matrix. For Binary data,
Logistic biplots have been recently developed.When data are nominal, linear or
even binary logistic biplots are not adequate and techniques as Multiple
Correspondence Analysis (MCA), Latent Trait Analysis (LTA) or Item Response
Theory for nominal items should be used instead. In this paper we extend the
binary logistic biplot to nominal data. The resulting method is termed Nominal
Logistic Biplot, although the variables are represented as convex prediction
regions rather than vectors. Using the methods from Computational Geometry, the
set of prediction regions is converted to a set of points in such a way that
the prediction for each individual is established by its closest category
point. Then interpretation is based on distances rather than on projections. We
study the geometry of such a representation and construct computational
algorithms for the estimation of parameters and the calculation of prediction
regions. Nominal Logistic Biplots extend both MCA and LTA in the sense that
gives a graphical representation for LTA similar to the one obtained in MCA.


title: Narrow orthogonally additive operators

abstract:
  We extend the notion of narrow operators to nonlinear maps on vector
lattices. The main objects are orthogonally additive operators and, in
particular, abstract Uryson operators. Most of the results extend known
theorems obtained by O. Maslyuchenko, V. Mykhaylyuk and the second named author
published in Positivity 13 (2009), pp. 459--495, for linear operators. For
instance, we prove that every orthogonally additive laterally-to-norm
continuous C-compact operator from an atomless Dedekind complete vector lattice
to a Banach space is narrow. Another result asserts that the set
U_{on}^{lc}(E,F) of all order narrow laterally continuous abstract Uryson
operators is a band in the vector lattice of all laterally continuous abstract
Uryson operators from an atomless vector lattice E with the principal
projection property to a Dedekind complete vector lattice F. The band generated
by the disjointness preserving laterally continuous abstract Uryson operators
is the orthogonal complement to U_{n}^{lc}(E,F).


title: Emergent Behaviors over Signed Random Networks in Dynamical Environments

abstract:
  We study asymptotic dynamical patterns that emerge among a set of nodes that
interact in a dynamically evolving signed random network. Node interactions
take place at random on a sequence of deterministic signed graphs. Each node
receives positive or negative recommendations from its neighbors depending on
the sign of the interaction arcs, and updates its state accordingly. Positive
recommendations follow the standard consensus update while two types of
negative recommendations, each modeling a different type of antagonistic or
malicious interaction, are considered. Nodes may weigh positive and negative
recommendations differently, and random processes are introduced to model the
time-varying attention that nodes pay to the positive and negative
recommendations. Various conditions for almost sure convergence, divergence,
and clustering of the node states are established. Some fundamental
similarities and differences are established for the two notions of negative
recommendations.


title: Computational Aspects of Optional P\'{o}lya Tree

abstract:
  Optional P\'{o}lya Tree (OPT) is a flexible non-parametric Bayesian model for
density estimation. Despite its merits, the computation for OPT inference is
challenging. In this paper we present time complexity analysis for OPT
inference and propose two algorithmic improvements. The first improvement,
named Limited-Lookahead Optional P\'{o}lya Tree (LL-OPT), aims at greatly
accelerate the computation for OPT inference. The second improvement modifies
the output of OPT or LL-OPT and produces a continuous piecewise linear density
estimate. We demonstrate the performance of these two improvements using
simulations.


title: Narrow operators on lattice-normed spaces

abstract:
  The aim of this article is to extend results of Maslyuchenko O., Mykhaylyuk
V. Popov M. about narrow operators on vector lattices. We give a new definition
of a narrow operator where a vector lattice as the domain space of a narrow
operator is replaced with a lattice-normed space. We prove that every
GAM-compact (bo)-norm continuous linear operator from a Banach-Kantorovich
space V to a Banach lattice Y is narrow. Then we show that, under some mild
conditions, a continuous dominated operator is narrow if and only if its exact
dominant is narrow.


title:
Anticipatory Buffer Control and Quality Selection for Wireless Video
  Streaming

abstract:
  Video streaming is in high demand by mobile users, as recent studies
indicate. In cellular networks, however, the unreliable wireless channel leads
to two major problems. Poor channel states degrade video quality and interrupt
the playback when a user cannot sufficiently fill its local playout buffer:
buffer underruns occur. In contrast to that, good channel conditions cause
common greedy buffering schemes to pile up very long buffers. Such
over-buffering wastes expensive wireless channel capacity.
  To keep buffering in balance, we employ a novel approach. Assuming that we
can predict data rates, we plan the quality and download time of the video
segments ahead. This anticipatory scheduling avoids buffer underruns by
downloading a large number of segments before a channel outage occurs, without
wasting wireless capacity by excessive buffering. We formalize this approach as
an optimization problem and derive practical heuristics for segmented video
streaming protocols (e.g., HLS or MPEG DASH). Simulation results and testbed
measurements show that our solution essentially eliminates playback
interruptions without significantly decreasing video quality.


title:
Photon flux and distance from the source: consequences for quantum
  foundations and technologies

abstract:
  The paper explores the fundamental physical principles of quantum mechanics
(in fact, quantum field theory) which limit the bit rate for long distances.
Propagation of photons in optical fibers is modeled using methods of quantum
electrodynamics. We define photon "duration" as the standard deviation of the
photon arrival time; we find its asymptotics for long distances and then obtain
the main result of the paper: the linear dependence of photon duration on the
distance. This effect puts the limit to joint increasing of the photon flux and
the distance from the source and it has important consequences both for quantum
information technologies and quantum foundations. Once quantum communication
develops into a real technology, it would be appealing to the engineers to
increase both the photon flux and the distance. And here our "photon
flux/distance effect" has to be taken into account (at least if successively
emitted photons are considered as independent). This effect also has to be
taken into account in a loophole free test of Bell's type -- to close jointly
the detection and locality loopholes.


title:
Third and Fourth-order iterative methods for solving systems of
  nonlinear equations

abstract:
  The object of the present paper is to extend the third-order iterative method
for solving nonlinear equations into systems of nonlinear equations. Since our
motive is to develop the method which improve the order of convergence of
Newton's method with minimum number of functional evaluations.To achieve this
goal,we have used weighted method. Computational efficiency is compared not
only traditional way but also recently introduced flops-like based concept.
Finally numerical results are given to confirm theoretical order of
convergence.


title:
Comparison of physical properties of quiet and active regions through
  the analysis of MHD simulations of the solar photosphere

abstract:
  Recent observations have shown that the photometric and dynamic properties of
granulation and of small-scale magnetic features depend on the amount of
magnetic flux of the region they are embedded in. We analyze results from
numerical Hydro and Magneto Hydrodynamic simulations characterized by different
amount of average magnetic flux and find qualitatively the same differences as
those reported from observations. We show that these different physical
properties result from the inhibition of convection induced by the presence of
the magnetic field, which changes the temperature stratification of both quiet
and magnetic regions. Our results are relevant for solar irradiance variations
studies, as such differences are still not properly taken into account in
irradiance reconstruction models.


title:
The lepton flavor violating signal of the charged scalar \phi^\pm and
  \phi^{\pm\pm} in photon-photon collision at the ILC

abstract:
  The hitherto unconstrained lepton flavor mixing, induced by the new charged
scalar \phi^\pm and \phi^{\pm\pm} predicted by many new physics models such as
higgs triplet models, may lead to the lepton flavor violating productions of
\tau\bar \mu, \tau\bar e and \mu\bar e in photon-photon collision at the
proposed international linear collider.
  In this paper, we consider the contributions of the \phi^\pm and
\phi^{\pm\pm} in the context of the higgs triplet models to the processes
\gamma\gamma\to l_i\bar l_j (i, j= e, \mu, \tau, i\neq j) and find that they
can be good channels to probe these new physics models. The lepton flavor
violating processes \gamma\gamma\to l_i\bar l_j (i, j= e, \mu,\tau,i\neq j)
occur at a high rate due to the large mixing angle and the large flavor
changing coupling, so, in view of the low standard model backgrounds, they may
reach the detectable level of the ILC for a large part of the parameter space.
Since the rates predicted by the standard model are far below the detectable
level, these processes may serve as a sensitive probe for such new physics
models.


title:
Anomalously Strong 2D Band Intensity in Twisted Bilayer Graphene: Raman
  Evidence for Doubly Degenerate Dirac Band

abstract:
  We report the observation of anomalously strong 2D band in twisted bilayer
graphene (tBLG) with large rotation angles under 638-nm and 532-nm visible
laser excitation. The 2D band of tBLG can reach four times as opposed to two
times as strong as that of single layer graphene. The same tBLG samples also
exhibit rotation dependent G-line resonances and folded phonons under 364-nm UV
laser excitation. We attribute this 2D band Raman enhancement to the
constructive quantum interference between two double-resonance Raman pathways
which are enabled by nearly degenerate Dirac band in tBLG Moir\'e
superlattices.


title: Magnetic fields in beta Cep, SPB, and Be stars

abstract:
  Recent observational and theoretical results emphasize the potential
significance of magnetic fields for structure, evolution, and environment of
massive stars. Depending on their spectral and photometric behavior, the upper
main-sequence B-type stars are assigned to different groups, such as beta Cep
stars and slowly pulsating B (SPB) stars, He-rich and He-deficient Bp stars, Be
stars, BpSi stars, HgMn stars, or normal B-type stars. All these groups are
characterized by different magnetic field geometry and strength, from fields
below the detection limit of a few Gauss up to tens of kG. Our collaboration
was the first to systematically study the magnetic fields in representative
samples of different types of main-sequence B stars. In this article, we give
an overview about what we have learned during the last years about magnetic
fields in beta Cep, SPB, and Be stars.


title: High Precision Arithmetic for Scientific Applications

abstract:
  All but a few digital computers used for scientific computations have
supported floating-point and digital arithmetic of rather limited numerical
precision. The underlying assumptions were that the systems being studied were
basically deterministic and of limited complexity. The ideal scientific
paradigm was the orbits of the major planets, which could be observed with high
precision, predicted for thousands of years into the future, and extrapolated
for thousands of years into the past. Much the same technology that has made
computers possible has also provided instrumentation that has vastly expanded
the scope and precision of scientific analysis. Complex nonlinear systems
exhibiting so-called chaotic dynamics are now fair game for scientists and
engineers in every discipline. Today it seems that computers need to enhance
the precision of their numerical computations to support the needs of science.
However, there is no need to wait for the necessary updates in both hardware
and software; it is easy enough to monitor numerical precision with a few minor
modifications to existing software.


title: HARPS spectropolarimetry of O and B-type stars

abstract:
  Our knowledge of the presence and the strength of magnetic fields in massive
O and B-type stars remains very poor. Recent observations indicate that the
presence of magnetic fields is responsible for a wide range of phenomena
observed in massive stars at different wavelengths, such as chemical
peculiarity, excess of emission in UV-wind lines and periodic UV wind-line
variability, unusual X-ray emission, and cyclic variability in Halpha and He II
4686. However, it is difficult to establish relationships to multiwavelength
diagnostics, as the strength of the detected magnetic fields and their geometry
differ from one star to the other. In this work, we present new magnetic field
measurements in a number of O and B-type stars of different classification
observed with HARPS in spectropolarimetric mode.


title: PRoMoTo 2013 proceedings

abstract:
  Programming for Mobile and Touch (PRoMoTo'13) was held at the 2013 ACM
SIGPLAN conference on Systems, Programming, Languages and Applications (SPLASH
2013), October 2013 in Indianapolis, USA. Submissions for this event were
invited in the general area of mobile and touch-oriented programming languages
and programming environments, and teaching of programming for mobile devices.
These are proceedings of the PRoMoTo'13.


title: Establishing the link between HgMn and PGa stars

abstract:
  We discuss most recent spectroscopic and spectropolarimetric observations of
the star HD 19400 representative of the group of PGa stars. Our
high-spectral-resolution study of abundances, line profile variability, and the
longitudinal magnetic field of HD 19400 discloses a remarkable similarity
between this group and the group of HgMn stars.


title:
The multi-vehicle covering tour problem: building routes for urban
  patrolling

abstract:
  In this paper we study a particular aspect of the urban community policing:
routine patrol route planning. We seek routes that guarantee visibility, as
this has a sizable impact on the community perceived safety, allowing quick
emergency responses and providing surveillance of selected sites (e.g.,
hospitals, schools). The planning is restricted to the availability of vehicles
and strives to achieve balanced routes. We study an adaptation of the model for
the multi-vehicle covering tour problem, in which a set of locations must be
visited, whereas another subset must be close enough to the planned routes. It
constitutes an NP-complete integer programming problem. Suboptimal solutions
are obtained with several heuristics, some adapted from the literature and
others developed by us. We solve some adapted instances from TSPLIB and an
instance with real data, the former being compared with results from
literature, and latter being compared with empirical data.


title:
Evaluating Sliding and Sticky Target Policies by Measuring Temporal
  Drift in Acyclic Walks Through a Web Archive

abstract:
  When a user views an archived page using the archive's user interface (UI),
the user selects a datetime to view from a list. The archived web page, if
available, is then displayed. From this display, the web archive UI attempts to
simulate the web browsing experience by smoothly transitioning between archived
pages. During this process, the target datetime changes with each link
followed; drifting away from the datetime originally selected. When browsing
sparsely-archived pages, this nearly-silent drift can be many years in just a
few clicks. We conducted 200,000 acyclic walks of archived pages, following up
to 50 links per walk, comparing the results of two target datetime policies.
The Sliding Target policy allows the target datetime to change as it does in
archive UIs such as the Internet Archive's Wayback Machine. The Sticky Target
policy, represented by the Memento API, keeps the target datetime the same
throughout the walk. We found that the Sliding Target policy drift increases
with the number of walk steps, number of domains visited, and choice (number of
links available). However, the Sticky Target policy controls temporal drift,
holding it to less than 30 days on average regardless of walk length or number
of domains visited. The Sticky Target policy shows some increase as choice
increases, but this may be caused by other factors. We conclude that based on
walk length, the Sticky Target policy generally produces at least 30 days less
drift than the Sliding Target policy.


title:
Chaos Forgets and Remembers: Measuring Information Creation,
  Destruction, and Storage

abstract:
  The hallmark of deterministic chaos is that it creates information---the rate
being given by the Kolmogorov-Sinai metric entropy. Since its introduction half
a century ago, the metric entropy has been used as a unitary quantity to
measure a system's intrinsic unpredictability. Here, we show that it naturally
decomposes into two structurally meaningful components: A portion of the
created information---the ephemeral information---is forgotten and a
portion---the bound information---is remembered. The bound information is a new
kind of intrinsic computation that differs fundamentally from information
creation: it measures the rate of active information storage. We show that it
can be directly and accurately calculated via symbolic dynamics, revealing a
hitherto unknown richness in how dynamical systems compute.

categories: nlin.CD cond-mat.stat-mech cs.IT math.DS math.IT


title:
A two-coil mutual inductance technique to study matching effect in
  disordered NbN thin films

abstract:
  Although matching effects in superconducting anti-dot arrays have been
studied extensively through magneto-resistance oscillations, these
investigations have been restricted to a very narrow temperature window close
to the superconducting transition. Here we report a "two coil" mutual
inductance technique, which allows the study of this phenomenon deep in the
superconducting state, through a direct measurement of the magnetic field
variation of the shielding response. We demonstrate how this technique can be
used to resolve outstanding issues on the origin of matching effects in
superconducting thin films with periodic array of holes grown on anodized
alumina membranes.


title:
Strong uniqueness for stochastic evolution equations with unbounded
  measurable drift term

abstract:
  We consider stochastic evolution equations in Hilbert spaces with merely
measurable and locally bounded drift term $B$ and cylindrical Wiener noise. We
prove pathwise (hence strong) uniqueness in the class of global solutions. This
paper extends our previous paper (Da Prato, Flandoli, Priola and M. Rockner,
Annals of Prob., published online in 2012) which generalized Veretennikov's
fundamental result to infinite dimensions assuming boundedness of the drift
term. As in our previous paper pathwise uniqueness holds for a large class, but
not for every initial condition. We also include an application of our result
to prove existence of strong solutions when the drift $B$ is only measurable,
locally bounded and grows more than linearly.


title: Microgrid - The microthreaded many-core architecture

abstract:
  Traditional processors use the von Neumann execution model, some other
processors in the past have used the dataflow execution model. A combination of
von Neuman model and dataflow model is also tried in the past and the resultant
model is referred as hybrid dataflow execution model. We describe a hybrid
dataflow model known as the microthreading. It provides constructs for
creation, synchronization and communication between threads in an intermediate
language. The microthreading model is an abstract programming and machine model
for many-core architecture. A particular instance of this model is named as the
microthreaded architecture or the Microgrid. This architecture implements all
the concurrency constructs of the microthreading model in the hardware with the
management of these constructs in the hardware.


title:
Pareto optimality conditions and duality for vector quadratic fractional
  optimization problems

abstract:
  One of the most important optimality conditions to aid to solve a vector
optimization problem is the first-order necessary optimality condition that
generalizes the Karush-Kuhn-Tucker condition. However, to obtain the sufficient
optimality conditions, it is necessary to impose additional assumptions on the
objective functions and in the constraint set. The present work is concerned
with the constrained vector quadratic fractional optimization problem. It shows
that sufficient Pareto optimality conditions and the main duality theorems can
be established without the assumption of generalized convexity in the objective
functions, by considering some assumptions on a linear combination of Hessian
matrices instead. The main aspect of this contribution is the development of
Pareto optimality conditions based on a similar second-order sufficient
condition for problems with convex constraints, without convexity assumptions
on the objective functions. These conditions might be useful to determine
termination criteria in the development of algorithms.


title: Rational Ellipticity in Cohomogeneity Two

abstract:
  Let M be a compact, connected and simply-connected Riemannian manifold, and
suppose that G is a compact, connected Lie group acting on M by isometries. The
dimension of the space of orbits is called the cohomogeneity of the action. If
the direct sum of the higher homotopy groups of M, tensored with the field of
rational numbers, is a finite-dimensional vector space over the rationals, then
M is said to be rationally elliptic. It is known that M is rationally elliptic
if it supports an action of cohomogeneity zero or one. When the cohomogeneity
is two, this general result is no longer true. However, we prove that M is
rationally elliptic in the two-dimensional case under the added assumption that
M has nonnegative sectional curvature.


title:
An alternative formulation of Classical Mechanics based on an analogy
  with Thermodynamics

abstract:
  We study new Legendre transforms in classical mechanics and investigate some
of their general properties. The behaviour of the new functions is analyzed
under coordinate transformations.When invariance under different kinds of
transformations are considered, the new formulation is found to be completly
equivalent to the usual Lagrangian formulation, recovering well established
results like the conservation of the angular momentum. Furthermore, a natural
generalization of the Poisson Bracket is found to be inherent to the formalism
introduced. On the other hand, we find that with a convenient redefinition of
the Lagrangian, $\mathcal{L}^{\prime}=-\mathcal{L}$, it is possible to
establish an exact one-to-one mathematical correspondence between the
thermodynamic potentials and the new potentials of classical mechanics


title: On the asymptotic hyperstability of switched systems

abstract:
  Asymptotic hyperstability is achievable under certain switching laws if at
least one of the feed-forward parameterization: 1) possesses a strictly
positive real transfer function, 2) a minimum residence time interval is
respected for each activation time interval of such a parameterization, and 3)
a maximum allowable residence time interval is guaranteed for all active
parameterization which is not positive real.


title:
Darboux and binary Darboux transformations for discrete integrable
  systems 1. Discrete potential KdV equation

abstract:
  The Hirota-Miwa equation can be written in `nonlinear' form in two ways: the
discrete KP equation and, by using a compatible continuous variable, the
discrete potential KP equation. For both systems, we consider the Darboux and
binary Darboux transformations, expressed in terms of the continuous variable,
and obtain exact solutions in Wronskian and Grammian form. We discuss
reductions of both systems to the discrete KdV and discrete potential KdV
equations, respectively, and exploit this connection to find the Darboux and
binary Darboux transformations and exact solutions of these equations.


title: Counting of discrete Rossby/drift wave resonant triads (again)

abstract:
  The purpose of our earlier note (arXiv:1309.0405 [physics.flu-dyn]) was to
remove the confusion over counting of resonant wave triads for Rossby and drift
waves in the context of the Charney-Hasegawa-Mima equation. A comment by
Kartashov and Kartashova (arXiv:1309.0992v1 [physics.flu-dyn]) on that note has
further confused the situation. The present note aims to remove this
obfuscation.


title:
Development of Textured Magnesium Oxide Templates on Amorphous Polymer
  Surfaces Using Ion-Beam-Assisted-Deposition

abstract:
  Biaxially textured MgO templates have been successfully fabricated on several
amorphous polymer films including Kapton tapes, polyimide, Poly(methyl
methacrylate) (PMMA), and photoresist films using ion-beam-assisted-deposition
(IBAD). With a Y2O3 buffer layer on polymer surfaces, roughening of the polymer
surfaces due to preferential ion beam sputtering can be effectively reduced to
meet the surface compatibility requirement for IBAD-MgO texturing. In-plane
full-width-at-half-maximum (FWHM) of ~10.7 degrees and out-of-plane FWHM ~ 3.5
degrees have been obtained on homoepitaxial MgO films grown on top of the
IBAD-MgO template. This method provides a practical route for fabricating
epitaxial devices on polymers needed for flexible optoelectronics.


title:
Local Pareto optimality conditions for vector quadratic fractional
  optimization problems

abstract:
  There are several concepts and definitions that characterize and give
optimality conditions for solutions of a vector optimization problem. One of
the most important is the first-order necessary optimality condition that
generalizes the Karush-Kuhn-Tucker condition. This condition ensures the
existence of an arbitrary neighborhood that contains an local optimal solution.
The present work we introduce an alternative concept to identify the local
optimal solution neighborhood in vector optimization problems. The main aspect
of this contribution is the development of necessary and sufficient Pareto
optimality conditions for the solutions of a particular vector optimization
problem, where each objective function consists of a ratio quadratic functions
and the feasible set is defined by linear inequalities. We show how to
calculate the largest radius of the spherical region centered on a local Pareto
solution in which this solution is optimal. In this process we may conclude
that the solution is also globally optimal. These conditions might be useful to
determine termination criteria in the development of algorithms, including more
general problems in which quadratic approximations are used locally.


title:
On the classification of toroidal compactifications with
  $3\bar{c}_{2}=\bar{c}^{2}_{1}$ and $\bar{c}_{2}=1$

abstract:
  We classify the smallest finite volume complex hyperbolic surfaces with cusps
which admit smooth toroidal compactifications and which are not birational to a
bi-elliptic surface. Remarkably, there is only one such surface which appears
to be the compactification of a Picard modular surface.


title:
Fundamental limitations in spin-ensemble quantum memories for cavity
  fields

abstract:
  Inhomogeneously broadened spin ensembles play an important role in
present-day implementation of hybrid quantum processing architectures. When
coupled to a resonator such an ensemble may serve as a multi-mode quantum
memory for the resonator field, and by employing spin-refocusing techniques the
quantum memory time can be extended to the coherence time of individual spins
in the ensemble. In the present paper we investigate such a memory protocol
capable of storing an unknown resonator-field state, and we examine separately
the various constituents of the protocol: the storage and read-out part, the
memory hold time with the spin ensemble and resonator field decoupled, and the
parts employing spin refocusing techniques. Using both analytical and numerical
methods we derive how the obtainable memory performance scales with various
physical parameters.


title:
Approaches to modelling irradiation-induced processes in transmission
  electron microscopy

abstract:
  The recent progress in high-resolution transmission electron microscopy
(HRTEM) has given rise to the possibility of in situ observations of
nanostructure transformations and chemical reactions induced by electron
irradiation. In this article we briefly summarise experimental observations and
discuss in detail atomistic modelling of irradiation-induced processes in
HRTEM, as well as mechanisms of such processes recognised due to modelling.
Accurate molecular dynamics (MD) techniques based on first principles or
tight-binding models are employed in the analysis of single irradiation-induced
events, and classical MD simulations are combined with a kinetic Monte Carlo
algorithm to simulate continuous irradiation of nanomaterials. It has been
shown that sulphur-terminated graphene nanoribbons are formed inside carbon
nanotubes as a result of an irradiation-selective chemical reaction. The
process of fullerene formation in HRTEM during continuous electron irradiation
of a small graphene flake has been simulated, and mechanisms driving this
transformation analysed.


title: Higher dimensional non-Kerr black hole and energy extraction

abstract:
  We investigate the properties of the horizons and ergosphere in a rotating
higher dimensional (HD) deformed Kerr-like black hole. We also explicitly bring
out the effect of deformation parameter $\epsilon$ and the extra dimension on
the efficiency of the Penrose process of energy extraction from a black hole.
It is interesting to see that the ergosphere size is sensitive to the
deformation parameter $\epsilon$ as well as spacetime dimensions $D$. This
gives rise to a much richer structure of the ergosphere in a HD non-Kerr black
hole, thereby making the Penrose process more efficient compared with that of
the four-dimensional Kerr black hole.


title: On the cohomology of real Grassmann manifolds

abstract:
  We give an explicit and simple construction of the incidence graph for the
integral cohomology of real Grassmann manifold Gr(k,n) in terms of the Young
diagrams filled with the letter q in checkered pattern. It turns out that there
are two types of graphs, one for the trivial coefficients and other for the
twisted coefficients, and they compute the homology groups of the orientable
and non-orientable cases of Gr(k,n) via the Poincar\'e-Verdier duality. We also
give an explicit formula of the Poincar\'e polynomial for Gr(k,n) and show that
the Poincar\'e polynomial is also related to the number of points on Gr(k,n)
over a finite field {F}_q with q being a power of prime which is also used in
the Young diagrams.


title: More Jordan type inequalities

abstract:
  The function $ \tan(\pi x / 2) / (\pi x / 2) $ is expanded into a Laurent
series of $ 1 - x^2 $, where the coefficients are given explicitly as
combinations of zeta function of even integers. This is used to achieve a
sequence of upper and lower bounds which are very precise even at the poles $ x
= 1, -1 $.
  Similar results are obtained for other trigonometric functions with poles.


title: On the k-Atomicity-Verification Problem

abstract:
  Modern Internet-scale storage systems often provide weak consistency in
exchange for better performance and resilience. An important weak consistency
property is k-atomicity, which bounds the staleness of values returned by read
operations. The k-atomicity-verification problem (or k-AV for short) is the
problem of deciding whether a given history of operations is k-atomic. The 1-AV
problem is equivalent to verifying atomicity/linearizability, a well-known and
solved problem. However, for k > 2, no polynomial-time k-AV algorithm is known.
  This paper makes the following contributions towards solving the k-AV
problem. First, we present a simple 2- AV algorithm called LBT, which is likely
to be efficient (quasilinear) for histories that arise in practice, although it
is less efficient (quadratic) in the worst case. Second, we present a more
involved 2-AV algorithm called FZF, which runs efficiently (quasilinear) even
in the worst case. To our knowledge, these are the first algorithms that solve
the 2-AV problem fully. Third, we show that the weighted k-AV problem, a
natural extension of the k-AV problem, is NP-complete.


title:
Patterns formation in axially symmetric
  Landau-Lifshitz-Gilbert-Slonczewski equations

abstract:
  The Landau-Lifshitz-Gilbert-Slonczewski equation describes magnetization
dynamics in the presence of an applied field and a spin polarized current. In
the case of axial symmetry and with focus on one space dimension, we
investigate the emergence of space-time patterns in the form of wavetrains and
coherent structures, whose local wavenumber varies in space. A major part of
this study concerns existence and stability of wavetrains and of front- and
domain wall-type coherent structures whose profiles asymptote to wavetrains or
the constant up-/down-magnetizations. For certain polarization the Slonczewski
term can be removed which allows for a more complete charaterization, including
soliton-type solutions. Decisive for the solution structure is the polarization
parameter as well as size of anisotropy compared with the difference of field
intensity and current intensity normalized by the damping.


title:
Adaptive construction of surrogates for the Bayesian solution of inverse
  problems

abstract:
  The Bayesian approach to inverse problems typically relies on posterior
sampling approaches, such as Markov chain Monte Carlo, for which the generation
of each sample requires one or more evaluations of the parameter-to-observable
map or forward model. When these evaluations are computationally intensive,
approximations of the forward model are essential to accelerating sample-based
inference. Yet the construction of globally accurate approximations for
nonlinear forward models can be computationally prohibitive and in fact
unnecessary, as the posterior distribution typically concentrates on a small
fraction of the support of the prior distribution. We present a new approach
that uses stochastic optimization to construct polynomial approximations over a
sequence of measures adaptively determined from the data, eventually
concentrating on the posterior distribution. The approach yields substantial
gains in efficiency and accuracy over prior-based surrogates, as demonstrated
via application to inverse problems in partial differential equations.


title: p-Pb Results from ALICE with an Emphasis on Centrality Determination

abstract:
  New ALICE results concerning particle production at low and intermediate
transverse momenta in p-Pb collisions at a centre of mass energy of 5.02 TeV
per nucleon pair are briefly discussed. Emphasis is given to the determination
of centrality in p-Pb and their implications for binary scaling of hard
processes.


title: Euclidean arrangements in Banach spaces

abstract:
  We study the way in which the Euclidean subspaces of a Banach space fit
together, somewhat in the spirit of the Ka\v{s}in decomposition. The main tool
that we introduce is an estimate regarding the convex hull of a convex body in
John's position with a Euclidean ball of a given radius, which leads to a new
and simplified proof of the randomized isomorphic Dvoretzky theorem. Our
results also include a characterization of spaces with nontrivial cotype in
terms of arrangements of Euclidean subspaces.


title: On the (co)homology of the poset of weighted partitions

abstract:
  We consider the poset of weighted partitions $\Pi_n^w$, introduced by
Dotsenko and Khoroshkin in their study of a certain pair of dual operads. The
maximal intervals of $\Pi_n^w$ provide a generalization of the lattice $\Pi_n$
of partitions, which we show possesses many of the well-known properties of
$\Pi_n$. In particular, we prove these intervals are EL-shellable, we show that
the M\"obius invariant of each maximal interval is given up to sign by the
number of rooted trees on on node set $\{1,2,\dots,n\}$ having a fixed number
of descents, we find combinatorial bases for homology and cohomology, and we
give an explicit sign twisted $\mathfrak{S}_n$-module isomorphism from
cohomology to the multilinear component of the free Lie algebra with two
compatible brackets. We also show that the characteristic polynomial of
$\Pi_n^w$ has a nice factorization analogous to that of $\Pi_n$.


title: CMB ISW-lensing bispectrum from cosmic strings

abstract:
  We study the effect of weak lensing by cosmic (super-)strings on the
higher-order statistics of the cosmic microwave background (CMB). A cosmic
string segment is expected to cause weak lensing as well as an integrated
Sachs-Wolfe (ISW) effect, the so-called Gott-Kaiser-Stebbins (GKS) effect, to
the CMB temperature fluctuation, which are thus naturally cross-correlated. We
point out that, in the presence of such a correlation, yet another kind of the
post-recombination CMB temperature bispectra, the ISW-lensing bispectra, will
arise in the form of products of the auto- and cross-power spectra. We first
present an analytic method to calculate the autocorrelation of the temperature
fluctuations induced by the strings, and the cross-correlation between the
temperature fluctuation and the lensing potential both due to the string
network. In our formulation, the evolution of the string network is assumed to
be characterized by the simple analytic model, the velocity-dependent one scale
model, and the intercommutation probability is properly incorporated in orderto
characterize the possible superstringy nature. Furthermore, the obtained power
spectra are dominated by the Poisson-distributed string segments, whose
correlations are assumed to satisfy the simple relations. We then estimate the
signal-to-noise ratios of the string-induced ISW-lensing bispectra and discuss
the detectability of such CMB signals from the cosmic string network. It is
found that in the case of the smaller string tension, $G\mu\ll 10^{-7}$\,, the
ISW-lensing bispectrum induced by a cosmic string network can constrain the
string-model parameters even more tightly than the purely GKS-induced
bispectrum in the ongoing and future CMB observations on small scales.


title: SU(3) chiral dynamics and baryon-baryon interactions

abstract:
  We calculate hyperon-nucleon and hyperon-hyperon interactions at
next-to-leading order in SU(3) baryon chiral perturbation theory extending
earlier work by the Bonn-Juelich group. The constructed potentials in momentum
space include all one- and two-meson exchange terms generated by the SU(3)
chiral Lagrangian. Effects from intermediate decuplet baryons are considered as
well. These chiral baryon-baryon potentials, together with appropriate contact
terms, provide a new basis for systematic studies of hyperon-nucleon scattering
and light hypernuclei.


title: Quantum Pfaffians and Hyper-Pfaffians

abstract:
  The concept of the quantum Pfaffian is rigorously examined and refurbished
using the new method of quantum exterior algebras. We derive a complete family
of Pl\"ucker relations for the quantum linear transformations, and then use
them to give an optimal set of relations required for the quantum Pfaffian. We
then give the formula between the quantum determinant and the quantum Pfaffian
and prove that any quantum determinant can be expressed as a quantum Pfaffian.
Finally the quantum hyper-Pfaffian is introduced, and we prove a similar result
of expressing quantum determinants in terms of quantum hyper-Pfaffians at
modular cases.

categories: math.QA hep-th math-ph math.CO math.MP math.RT


title:
BRITE-Constellation: Nanosatellites for Precision Photometry of Bright
  Stars

abstract:
  BRITE-Constellation (where BRITE stands for BRIght Target Explorer) is an
international nanosatellite mission to monitor photometrically, in two colours,
brightness and temperature variations of stars brighter than V = 4. The current
mission design consists of three pairs of 7 kg nanosats from Austria, Canada
and Poland carrying optical telescopes and CCDs. One instrument in each pair is
equipped with a blue filter; the other, a red filter. The first two nanosats
are UNIBRITE, designed and built by University of Toronto Institute for
Aerospace Studies - Space Flight Laboratory and its twin, BRITE-Austria, built
by the Technical University Graz with support of UTIAS-SFL. They were launched
on 25 February 2013 by the Indian Space Agency under contract to the Canadian
Space Agency into a low-Earth dusk-dawn polar orbit.


title: Mock galaxy catalogs using the quick particle mesh method

abstract:
  Sophisticated analysis of modern large-scale structure surveys requires mock
catalogs. Mock catalogs are used to optimize survey design, test reduction and
analysis pipelines, make theoretical predictions for basic observables and
propagate errors through complex analysis chains. We present a new method,
which we call "quick particle mesh", for generating many large-volume,
approximate mock catalogs at low computational cost. The method is based on
using rapid, low-resolution particle mesh simulations that accurately reproduce
the large-scale dark matter density field. Particles are sampled from the
density field based on their local density such that they have N-point
statistics nearly equivalent to the halos resolved in high-resolution
simulations, creating a set of mock halos that can be populated using halo
occupation methods to create galaxy mocks for a variety of possible target
classes.


title:
Search for new heavy neutral bosons decaying into a dilepton pair with
  the CMS detector at sqrt(s) = 8 TeV

abstract:
  Several theories beyond the Standard Model predict the existence of new heavy
neutral bosons. Such particles could be produced in significant amounts at the
LHC and their decay into a dilepton pair provides a clean signature with low
background contamination. The results of the analysis of the whole 2012 dataset
collected by the CMS experiment at a center of mass energy of 8 TeV are
presented. No evidence for new physics is seen and upper limits on the cross
section production of such particles are extracted. These results can be turned
into lower limits on the mass of the heavy bosons, reaching values well above 2
TeV/c2 for many models.


title:
Some considerations on the back door theorem and conditional
  randomization

abstract:
  In this work we propose a different surgical modified model for the
construction of counterfactual variables under non parametric structural
equation models. This approach allows the simultaneous representation of
counterfactual responses and observed treatment assignment, at least when the
intervention is done in one node. Using the new proposal, the d-separation
criterion is used verify conditions related with ignorability or conditional
ignorability and a new proof of the back door theorem is provided under this
framework.


title:
Discovery of a Dynamical Cold Point in the Heart of the Sagittarius dSph
  Galaxy with Observations from the APOGEE Project

abstract:
  The dynamics of the core of the Sagittarius (Sgr) dwarf spheroidal (dSph)
galaxy are explored using high-resolution (R~22,500), H-band, near-infrared
spectra of over 1,000 giant stars in the central 3 deg^2 of the system, of
which 328 are identified as Sgr members. These data, among some of the earliest
observations from the SDSS-III/Apache Point Observatory Galactic Evolution
Experiment (APOGEE) and the largest published sample of high resolution Sgr
dSph spectra to date, reveal a distinct gradient in the velocity dispersion of
Sgr from 11-14 km/s for radii >0.8 degrees from center to a dynamical cold
point of 8 km/s in the Sgr center --- a trend differing from that found in
previous kinematical analyses of Sgr over larger scales that suggest a more or
less flat dispersion profile at these radii. Well-fitting mass models with
either cored and cusped dark matter distributions can be found to match the
kinematical results, although the cored profile succeeds with significantly
more isotropic stellar orbits than required for a cusped profile. It is
unlikely that the cold point reflects an unusual mass distribution. The
dispersion gradient may arise from variations in the mixture of populations
with distinct kinematics within the dSph; this explanation is suggested (e.g.,
by detection of a metallicity gradient across similar radii), but not
confirmed, by the present data. Despite these remaining uncertainties about
their interpretation, these early test data (including some from instrument
commissioning) demonstrate APOGEE's usefulness for precision dynamical studies,
even for fields observed at extreme airmasses.


title:
Zero field entanglement in dipolar coupling spin system at negative
  temperatures

abstract:
  A dipolar coupled spin system can achieve internal thermodynamic equilibrium
states at negative absolute temperature. We study analytically and numerically
the temperature dependence of the concurrence in a dipolar coupled spin-1/2
system in both non-zero and zero fields and show that, at negative
temperatures, entangled states can exist even in zero magnetic field.


title:
Perturbations to aquatic photosynthesis due to high-energy cosmic ray
  induced muon flux in the extragalactic shock model

abstract:
  We modify a mathematical model of photosynthesis to quantify the
perturbations that high energy muons could make on aquatic primary
productivity. Then we apply this in the context of the extragalactic shock
model, according to which Earth receives an enhanced dose of high-energy cosmic
rays when it is at the galactic north. We obtain considerable reduction in the
photosynthesis rates, consistent with potential drops in biodiversity.


title:
Electron-acoustic solitary pulses and double layers in multi-component
  plasmas

abstract:
  We consider the nonlinear propagation of finite amplitude electron-acoustic
waves (EAWs) in multi-component plasmas composed of two distinct groups of
electrons (cold and hot components), and non-isothermal ions. We use the
continuity and momentum equations for cold inertial electrons, Boltzmann law
for inertialess hot electrons, non-isothermal density distribution for hot
ions, and Poisson's equation to derive an energy integral with a modified
Sagdeev potential (MSP) for nonlinear EAWs. The MSP is analyzed to demonstrate
the existence of arbitrary amplitude EA solitary pulses (EASPs) and EA double
layers (EA-DLs). Small amplitude limits have also been considered and
analytical results for EASPs and EA-DLs are presented. The implication of our
results to space and laboratory plasmas is briely discussed.


title: Dynamical stability of algebraic Ricci solitons

abstract:
  We consider dynamical stability for a modified Ricci flow equation whose
stationary solutions include Einstein and Ricci soliton metrics. Our focus is
on homogeneous metrics on non-compact manifolds. Following the program of
Guenther, Isenberg, and Knopf, we define a class of weighted little H\"older
spaces with certain interpolation properties that allow the use of maximal
regularity theory and the application of a stability theorem of Simonett. With
this, we derive two stability theorems, one for a class of Einstein metrics and
one for a class of non-Einstein Ricci solitons. Using linear stability results
of Jablonski, Petersen, and the first author, we obtain dynamical stability for
many specific Einstein and Ricci soliton metrics on simply connected solvable
Lie groups.


title: Detection and Isolation of Failures in Linear Multi-Agent Networks

abstract:
  In this paper the focus is on the relationship between the occurrence of
failures in a (directed or undirected) network of linear single integrator
agents and the presence of jump discontinuities in the derivatives of the
network output. Based on this relationship, an algorithm for sensor placement
is proposed, which enables the designer to detect and isolate any link failures
across the network, based on the jump discontinuities observed by the sensor
nodes. These results are explained through elaborative examples and computer
experiments.


title:
Magnetic Orders of Correlated Topological Insulators at Finite
  Temperature

abstract:
  In this paper, we study the magnetic orders of two dimensional correlated
topological insulators including the correlated Chern insulator and the
correlated Z2 topological insulator at finite temperature. For the 2D
correlated Chern insulator, we found that thermal-fluctuation-induced magnetic
order appears in the intermediate interaction region of the correlated Chern
insulator. On the contrary, for the correlated Z2 topological insulator there
doesn't exist the thermal-fluctuation-induced magnetic order. In the end, we
give an explanation on the difference.


title: Wall to Wall Optimal Transport

abstract:
  The calculus of variations is employed to find steady divergence-free
velocity fields that maximize transport of a tracer between two parallel walls
held at fixed concentration for one of two constraints on flow strength: a
fixed value of the kinetic energy or a fixed value of the enstrophy. The
optimizing flows consist of an array of (convection) cells of a particular
aspect ratio Gamma. We solve the nonlinear Euler-Lagrange equations
analytically for weak flows and numerically (and via matched asymptotic
analysis in the fixed energy case) for strong flows. We report the results in
terms of the Nusselt number Nu, a dimensionless measure of the tracer
transport, as a function of the Peclet number Pe, a dimensionless measure of
the energy or enstrophy of the flow. For both constraints the maximum transport
Nu_{MAX}(Pe) is realized in cells of decreasing aspect ratio Gamma_{opt}(Pe) as
Pe increases. For the fixed energy problem, Nu_{MAX} \sim Pe and Gamma_{opt}
\sim Pe^{-1/2}, while for the fixed enstrophy scenario, Nu_{MAX} \sim
Pe^{10/17} and Gamma_{opt} \sim Pe^{-0.36}. We also interpret our results in
the context of certain buoyancy-driven Rayleigh-Benard convection problems that
satisfy one of the two intensity constraints, enabling us to investigate how
the transport scalings compare with upper bounds on Nu expressed as a function
of the Rayleigh number \Ra. For steady convection in porous media,
corresponding to the fixed energy problem, we find Nu_{MAX} \sim \Ra and
Gamma_{opt} \sim Ra^{-1/2}$, while for steady convection in a pure fluid layer
between free-slip isothermal walls, corresponding to fixed enstrophy transport,
Nu_{MAX} \sim Ra^{5/12} and Gamma_{opt} \sim Ra^{-1/4}.

categories: physics.flu-dyn math-ph math.MP math.OC physics.ao-ph


title: H\"ormander's theorem for stochastic partial differential equations

abstract:
  We prove H\"ormander's type hypoellipticity theorem for stochastic partial
differential equations when the coefficients are only measurable with respect
to the time variable. The need for such kind of results comes from filtering
theory of partially observable diffusion processes, when even if the initial
system is autonomous, the observation process enters the coefficients of the
filtering equation and makes them time-dependent with no good control on the
smoothness of the coefficients with respect to the time variable.


title: Alternating Turing machines for inductive languages

abstract:
  We show that alternating Turing machines, with a novel and natural definition
of acceptance, accept precisely the inductive (Pi-1-1) languages. Total
alternating machines, that either accept or reject each input, accept precisely
the hyper-elementary (Delta-1-1) languages. Moreover, bounding the permissible
number of alternations yields a characterization of the levels of the
arithmetical hierarchy. Notably, these results use simple finite computing
devices, with finitary and discrete operational semantics, and neither the
results nor their proofs make any use of transfinite ordinals. Our
characterizations elucidate the analogy between the polynomial-time hierarchy
and the arithmetical hierarchy, as well as between their respective limits,
namely polynomial-space and Pi-1-1.


title:
Hypoellipticity for filtering problems of partially observable diffusion
  processes

abstract:
  We prove that under H\"ormander's type conditions on the coefficients of the
unobservable component of a partially observable diffusion process the
filtering density is infinitely differentiable and can be represented as the
integral of an infinitely differentiable kernel against the prior initial
distribution. These results are derived from more general results obtained for
SPDEs. One the main novelty of the paper is the existence and smoothness of the
kernel, another that we allow the coefficients of our partially observable
process to be just measurable with respect to the time variable.


title:
Simultaneous Transmission and Reception: Algorithm, Design and System
  Level Performance

abstract:
  Full Duplex or Simultaneous transmission and reception (STR) in the same
frequency at the same time can potentially double the physical layer capacity.
However, high power transmit signal will appear at receive chain as echoes with
powers much higher than the desired received signal. Therefore, in order to
achieve the potential gain, it is imperative to cancel these echoes. As these
high power echoes can saturate low noise amplifier (LNA) and also digital
domain echo cancellation requires unrealistically high resolution
analog-to-digital converter (ADC), the echoes should be cancelled or suppressed
sufficiently before LNA. In this paper we present a closed-loop echo
cancellation technique which can be implemented purely in analogue domain. The
advantages of our method are multiple-fold: it is robust to phase noise, does
not require additional set of antennas, can be applied to wideband signals and
the performance is irrelevant to radio frequency (RF) impairments in transmit
chain. Next, we study a few protocols for STR systems in carrier sense multiple
access (CSMA) network and investigate MAC level throughput with realistic
assumptions in both single cell and multiple cells. We show that STR can reduce
hidden node problem in CSMA network and produce gains of up to 279% in maximum
throughput in such networks. Finally, we investigate the application of STR in
cellular systems and study two new unique interferences introduced to the
system due to STR, namely BS-BS interference and UE-UE interference. We show
that these two new interferences will hugely degrade system performance if not
treated appropriately. We propose novel methods to reduce both interferences
and investigate the performances in system level.


title:
Bundle-Level Type Methods Uniformly Optimal for Smooth and Nonsmooth
  Convex Optimization

abstract:
  The main goal of this paper is to develop uniformly optimal first-order
methods for convex programming (CP). By uniform optimality we mean that the
first-order methods themselves do not require the input of any problem
parameters, but can still achieve the best possible iteration complexity
bounds. By incorporating a multi-step acceleration scheme into the well-known
bundle-level method, we develop an accelerated bundle-level (ABL) method, and
show that it can achieve the optimal complexity for solving a general class of
black-box CP problems without requiring the input of any smoothness
information, such as, whether the problem is smooth, nonsmooth or weakly
smooth, as well as the specific values of Lipschitz constant and smoothness
level. We then develop a more practical, restricted memory version of this
method, namely the accelerated prox-level (APL) method. We investigate the
generalization of the APL method for solving certain composite CP problems and
an important class of saddle-point problems recently studied by Nesterov
[Mathematical Programming, 103 (2005), pp 127-152]. We present promising
numerical results for these new bundle-level methods applied to solve certain
classes of semidefinite programming (SDP) and stochastic programming (SP)
problems.


title: Optimal Primal-Dual Methods for a Class of Saddle Point Problems

abstract:
  We present a novel accelerated primal-dual (APD) method for solving a class
of deterministic and stochastic saddle point problems (SPP). The basic idea of
this algorithm is to incorporate a multi-step acceleration scheme into the
primal-dual method without smoothing the objective function. For deterministic
SPP, the APD method achieves the same optimal rate of convergence as Nesterov's
smoothing technique. Our stochastic APD method exhibits an optimal rate of
convergence for stochastic SPP not only in terms of its dependence on the
number of the iteration, but also on a variety of problem parameters. To the
best of our knowledge, this is the first time that such an optimal algorithm
has been developed for stochastic SPP in the literature. Furthermore, for both
deterministic and stochastic SPP, the developed APD algorithms can deal with
the situation when the feasible region is unbounded, as long as a saddle point
exists. In the unbounded case, we incorporate the modified termination
criterion introduced by Monteiro and Svaiter in solving SPP problem posed as
monotone inclusion, and demonstrate that the rate of convergence of the APD
method depends on the distance from the initial point to the set of optimal
solutions.


title:
Stochastic First- and Zeroth-order Methods for Nonconvex Stochastic
  Programming

abstract:
  In this paper, we introduce a new stochastic approximation (SA) type
algorithm, namely the randomized stochastic gradient (RSG) method, for solving
an important class of nonlinear (possibly nonconvex) stochastic programming
(SP) problems. We establish the complexity of this method for computing an
approximate stationary point of a nonlinear programming problem. We also show
that this method possesses a nearly optimal rate of convergence if the problem
is convex. We discuss a variant of the algorithm which consists of applying a
post-optimization phase to evaluate a short list of solutions generated by
several independent runs of the RSG method, and show that such modification
allows to improve significantly the large-deviation properties of the
algorithm. These methods are then specialized for solving a class of
simulation-based optimization problems in which only stochastic zeroth-order
information is available.


title:
The Complexity of Large-scale Convex Programming under a Linear
  Optimization Oracle

abstract:
  This paper considers a general class of iterative optimization algorithms,
referred to as linear-optimization-based convex programming (LCP) methods, for
solving large-scale convex programming (CP) problems. The LCP methods, covering
the classic conditional gradient (CG) method (a.k.a., Frank-Wolfe method) as a
special case, can only solve a linear optimization subproblem at each
iteration. In this paper, we first establish a series of lower complexity
bounds for the LCP methods to solve different classes of CP problems, including
smooth, nonsmooth and certain saddle-point problems. We then formally establish
the theoretical optimality or nearly optimality, in the large-scale case, for
the CG method and its variants to solve different classes of CP problems. We
also introduce several new optimal LCP methods, obtained by properly modifying
Nesterov's accelerated gradient method, and demonstrate their possible
advantages over the classic CG for solving certain classes of large-scale CP
problems.


title: Design space exploration in the microthreaded many-core architecture

abstract:
  Design space exploration is commonly performed in embedded system, where the
architecture is a complicated piece of engineering. With the current trend of
many-core systems, design space exploration in general-purpose computers can no
longer be avoided. Microgrid is a complicated architecture, and therefor we
need to perform design space exploration. Generally, simulators are used for
the design space exploration of an architecture. Different simulators with
different levels of complexity, simulation time and accuracy are used.
Simulators with little complexity, low simulation time and reasonable accuracy
are desirable for the design space exploration of an architecture. These
simulators are referred as high-level simulators and are commonly used in the
design of embedded systems. However, the use of high-level simulation for
design space exploration in general-purpose computers is a relatively new area
of research.


title:
The co-evolution of brand effect and competitiveness in evolving
  networks

abstract:
  The principle that 'the brand effect is attractive' underlies preferential
attachment. Here we show that the brand effect is just one dimension of
attractiveness. Another dimension is competitiveness. We firstly develop a
general framework that allows us to investigate the competitive aspect of real
networks, instead of simply preferring popular nodes. Our model accurately
describes the evolution of social and technological networks. The phenomenon
which more competitive nodes become richer links can help us to understand the
evolution of many competitive systems in nature and society. In general, the
paper provides an explicit analytical expression of degree distributions of the
network. In particular, the model yields a nontrivial time evolution of nodes'
properties and scale-free behavior with exponents depending on the microscopic
parameters characterizing the competition rules. Secondly, through theoretical
analysis and numerical simulations, it reveals that our model has not only the
universality for the homogeneous weighted network, but also the character for
the heterogeneous weighted network. Thirdly, the paper also develops a model
based on a profit-driven mechanism. It can better describe the observed
phenomenon in enterprise cooperation networks. We show that standard
preferential attachment, the growing random graph, the initial attractiveness
model, the fitness model and weighted networks, can all be seen as degenerate
cases of our model.


title: Non-hyperbolic automatic groups and groups acting on CAT(0) cube complex

abstract:
  We discuss a problem posed by Gersten: Is every automatic group which does
not contain Z+Z subgroup, hyperbolic? To study this question, we define the
notion of "n-tracks of length n", which is a structure like Z+Z, and prove its
existence in the non-hyperbolic automatic groups with mild conditions. As an
application, we show that if a group acts effectively, cellularly, properly
discontinuously and cocompactly on a CAT(0) cube complex and its quotient is
"weakly special", then the above question is answered affirmatively.


title: Revisiting the Dichotomy of Early-type Galaxies

abstract:
  We study the relationship among isophotal shapes, central light profiles and
kinematic properties of early-type galaxies (ETGs) based on a compiled sample
of 184 ETGs. These sample galaxies are included in the Data Release 8 of Sloan
Digital Sky Survey (SDSS DR8) and have central light profiles and kinematic
properties available from the literature, which were measured based on Hubble
Space Telescope ({\it HST}) and \atlas\ integral-field spectrograph (IFS)
observations, respectively. We find that there is only a weak correlation
between the isophotal shape ($a_{4}/a$) and the central light profile (within
$1\,\rm kpc$) of ETGs. About two-fifths of "core" galaxies have disky
isophotes, while one-third of "power-law" galaxies are boxy deviated. Our
statistical results also show that there are weak correlations between galaxy
luminosity and dynamical mass with $a_{4}/a$, but such correlations are tighter
with central light profile. Moreover, no clear link has been found between the
isophotal shape and the S\' ersic index. Comparisons show that there are
similar correlations between $a_{4}/a$ and ellipticity and between $a_{4}/a$
and specific angular momentum $\lambda_{R_e/2}$ for "power-law" ETGs, but there
are no such correlations for "core" ETGs. Therefore, we speculate that the
bimodal classifications for ETGs are not as simple as previously thought,
though we also find that the most deviated disky ETGs are "power-law", more
elongated and fast rotators.


title:
Medium modifications of jet shapes in Pb+Pb collisions at
  $\sqrt{s_{_{\rm NN}}}$ = 2.76 TeV within a multiphase transport model

abstract:
  Within a multiphase transport model, medium modifications of differential jet
shapes are investigated in Pb+Pb collisions at $\sqrt{s_{_{\rm NN}}}$ = 2.76
TeV. The differential jet shapes are significantly modified by the strong
interactions between jets and a partonic medium in Pb+Pb collisions relative to
that in p+p collisions. The modifications are slightly weakened by the
hadronization of coalescence, but strengthened by resonance decays in hadronic
rescatterings. Subleading jets display larger medium modifications than leading
jets, especially in central Pb+Pb collisions with large dijet asymmetries.
These behaviors of medium modifications of differential jet shapes reflect a
dynamical evolution of redistribution of jet energy inside a quenched jet cone
in high-energy heavy-ion collisions.


title:
Galaxy And Mass Assembly (GAMA): improved cosmic growth measurements
  using multiple tracers of large-scale structure

abstract:
  We present the first application of a "multiple-tracer" redshift-space
distortion (RSD) analysis to an observational galaxy sample, using data from
the Galaxy and Mass Assembly survey (GAMA). Our dataset is an r < 19.8
magnitude-limited sample of 178,579 galaxies covering redshift interval z < 0.5
and area 180 deg^2. We obtain improvements of 10-20% in measurements of the
gravitational growth rate compared to a single-tracer analysis, deriving from
the correlated sample variance imprinted in the distributions of the
overlapping galaxy populations. We present new expressions for the covariances
between the auto-power and cross-power spectra of galaxy samples that are valid
for a general survey selection function and weighting scheme. We find no
evidence for a systematic dependence of the measured growth rate on the galaxy
tracer used, justifying the RSD modelling assumptions, and validate our results
using mock catalogues from N-body simulations. For multiple tracers selected by
galaxy colour, we measure normalized growth rates in two independent redshift
bins f*sigma_8(z=0.18) = 0.36 +/- 0.09 and f*sigma_8(z=0.38) = 0.44 +/- 0.06,
in agreement with standard GR gravity and other galaxy surveys at similar
redshifts.


title:
Influence of bulk inversion asymmetry on the magneto-optical spectrum of
  a HgTe topological insulator

abstract:
  The influence of bulk inversion asymmetry in [001] and [013] grown HgTe
quantum wells is investigated theoretically. The bulk inversion asymmetry leads
to an anti-crossing gap between two zero-mode Landau levels in a HgTe
topological insulator, i.e., the quantum well with inverted band structure. It
is found that this is the main contribution to the anti-crossing splitting
observed in recent experimental magneto spectroscopic measurements. The
relevant optical transitions involve different subbands, but the
electron-electron interaction induced depolarization shift is found to be
negligibly small. It is also found that the splitting of this anti-crossing
only depends weakly on the tilting angle when the magnetic field is tilted away
from the perpendicular direction to the quantum well. Thus, the strength of
bulk inversion asymmetry can be determined via a direct comparison between the
theoretical calculated one-electron energy levels and experimentally observed
anti-crossing energy gap.


title: Finiteness of attractors and repellers on sectional hyperbolic sets

abstract:
  We obtain an upper bound for the number of attractors and repellers that can
appear from small perturbations of a sectional hyperbolic set. This extends
results from [Sectional-Anosov flows in higher dimensions] and [The explosion
of singular-hyperbolic attractors].


title:
Exact wave functions for the edge state of a disk-shaped two dimensional
  topological insulator

abstract:
  We report the exact wave functions for the eigen state of a disk-shaped two
dimensional topological insulator. The property of the edge state whose energy
lies inside the bulk gap is studied. It is found that the edge state energy is
affected by the radius of the disk. For a fixed angular momentum index, there
is a critical disk radius below which there exists no edge state. The value of
this critical radius increases as the angular momentum index increases. In the
limit of large disk radius, the energy of the edge state approaches a limiting
value determined by the system parameters and independent of the angular
momentum index. The derivation from this limiting value is inversely
proportional to the radius with a coefficient proportional to the angular
momentum index. In the general case, the energy differences between two edge
states with adjacent angular momentum indexes are not equal. The exact and
analytical wave functions also facilitates the investigation of electronic
state in other structures of the two dimensional topological insulator.


title:
An Efficient Numerical Scheme for the Biharmonic Equation by Weak
  Galerkin Finite Element Methods on Polygonal or Polyhedral Meshes

abstract:
  This paper presents a new and efficient numerical algorithm for the
biharmonic equation by using weak Galerkin (WG) finite element methods. The WG
finite element scheme is based on a variational form of the biharmonic equation
that is equivalent to the usual $H^2$-semi norm. Weak partial derivatives and
their approximations, called discrete weak partial derivatives, are introduced
for a class of discontinuous functions defined on a finite element partition of
the domain consisting of general polygons or polyhedra. The discrete weak
partial derivatives serve as building blocks for the WG finite element method.
The resulting matrix from the WG method is symmetric, positive definite, and
parameter free. An error estimate of optimal order is derived in an
$H^2$-equivalent norm for the WG finite element solutions. Error estimates in
the usual $L^2$ norm are established, yielding optimal order of convergence for
all the WG finite element algorithms except the one corresponding to the lowest
order (i.e., piecewise quadratic elements). Some numerical experiments are
presented to illustrate the efficiency and accuracy of the numerical scheme.


title:
High Resolution Gamma Ray Detection in a Dual Phase Xenon Time
  Projection Chamber

abstract:
  Dual phase Xenon Time Projection Chambers (XeTPCs) are being used by several
experiments as a promising technique for direct detection of dark matter. We
report on the design and performance of a small 3-D sensitive dual phase XeTPC.
The position resolution is 2 mm in the center of detector, limited by the hole
size of the mesh at the proportional scintillation region. An energy resolution
of 1.6%({\sigma} /E) for 662 keV gamma rays is achieved by combining the
ionization and scintillation signals at a drift field of 0.5 kV/cm. This
represents the best energy resolution achieved among liquid xenon detectors.
The energy resolution is only slightly dependent on drift field. Better than 2%
energy resolution ({\sigma} /E) for 662 keV gamma rays can be achieved for
drift fields between 100 V/cm and 2 kV/cm. With high position and energy
resolutions, a dual phase XeTPC has also potential applications in surveys for
neutrinoless double-beta decay and in gamma ray imaging.


title: The cone of curves of K3 surfaces revisted

abstract:
  The main theorem of "S. J. Kov\'acs: The cone of curves of a K3 surface,
Math. Ann. 300 (1994), no. 4, 681-691" is proved in arbitrary characteristic.
The proof is essentially the same as in the original paper where it was stated
only over the complex numbers.


title:
A survey on the pseudo-process driven by the high-order heat-type
  equation $\partial/\partial t=\pm\partial^N/\partial x^N$ concerning the
  first hitting times and sojourn times

abstract:
  Fix an integer n>2 and let $(X(t))_{t\ge 0}$ be the pseudo-process driven by
the high-order heat-type equation $\partial/\partial t=\pm\partial^N/\partial
x^N$. The denomination "pseudo-process" means that $(X(t))_{t\ge 0}$ is related
to a signed measure (which is not a probability measure) with total mass equal
to 1. In this note, we present some results and discuss some problems
concerning the pseudo-distributions of the first overshooting times of a single
barrier $\{a\}$ or a double barrier $\{a,b\}$ by $(X(t))_{t\ge 0}$, as well as
those of the sojourn times of $(X(t))_{t\ge 0}$ in the intervals $[a,+\infty)$
and $[a,b]$ up to a fixed time.


title: A random walk model related to the clustering of membrane receptors

abstract:
  In a cellular medium, the plasmic membrane is a place of interactions between
the cell and its direct external environment. A classic model describes it as a
fluid mosaic. The fluid phase of the membrane allows a lateral degree of
freedom to its constituents: they seem to be driven by random motions along the
membrane. On the other hand, experimentations bring to light inhomogeneities on
the membrane; these micro-domains (the so-called rafts) are very rich in
proteins and phospholipids. Nevertheless, few functional properties of these
micro-domains have been shown and it appears necessary to build appropriate
models of the membrane for recreating the biological mechanism. In this
article, we propose a random walk model simulating the evolution of certain
constituents-the so-called ligands-along a heterogeneous membrane.
Inhomogeneities-the rafts-are described as being still clustered receptors. An
important variable of interest to biologists is the time that ligands and
receptors bind during a fixed amount of time. This stochastic time can be
interpreted as a measurement of affinity/sentivity of ligands for receptors. It
corresponds to the sojourn time in a suitable set for a certain random walk. We
provide a method of calculation for the probability distribution of this random
variable and we next determine explicitly this distribution in the simple case
when we are dealing with only one ligand and one receptor. We finally address
some further more realistic models.


title:
Call option on the maximum of the interest rate in the one factor affine
  model

abstract:
  We determine an explicit formula for the Laplace transform of the price of an
option on a maximal interest rate when the instantaneous rate satisfies
Cox-Ingersoll-Ross's model. This generalizes considerably one result of
Leblanc-Scaillet.


title: Bernstein processes described by forward and backward heat equations

abstract:
  We present some results on Bernstein processes which are Brownian diffusions
that appear in Euclidean Quantum Mechanics: We express the distributions of
these processes with the help of those of Bessel processes. We then determine
two solutions of the dual equation of the heat equation with potential. This
continues the calculation of Lescot for the solution with an Ornstein-Uhlenbek
process .


title: The Hardy space H1 in the rational Dunkl setting

abstract:
  This paper consists in a first study of the Hardy space H1 in the rational
Dunkl setting. Following Uchiyama's approach, we characterizee H1 atomically
and by means of the heat maximal operator. We also obtain a Fourier multiplier
theorem for H1. These results are proved here in the one-dimensional case and
in the product case.


title:
Integrating Communications and Merging Messaging via the eXtensible
  Messaging and Presence Protocol

abstract:
  Common problems affecting modern email usage include spam, lack of sender
verification, lack of built-in security and lack of message integrity. This
paper looks at how we can utilise the extensible messaging and presence
protocol also known as XMPP to, in time, replace email facilities. We present
several methods for initiating a transition away from SMTP for email to rely
upon the inherent benefits of XMPP with minimal disruption to existing networks
and email infrastructure. We look at how a program might be used to open an
existing POP3/IMAP account, scan for messages that can be sent to a XMPP
network user, extract the message and then deliver it the XMPP user's client.
We show that the system can be implemented and then deployed with a minimum of
hassle and network disruption to demonstrate XMPP as a reliable and fast
replacement for email as we know it today.


title: Lifshitz-sector mediated SUSY breaking

abstract:
  We propose a novel mechanism of SUSY breaking by coupling a Lorentz-invariant
supersymmetric matter sector to non-supersymmetric gravitational interactions
with Lifshitz scaling. The improved UV properties of Lifshitz propagators
moderate the otherwise uncontrollable ultraviolet divergences induced by
gravitational loops. This ensures that both the amount of induced Lorentz
violation and SUSY breaking in the matter sector are controlled by
Lambda_HL^2/M_P^2, the ratio of the Horava-Lifshitz cross-over scale Lambda_HL
to the Planck scale M_P. This ratio can be kept very small, providing a novel
way of explicitly breaking supersymmetry without reintroducing fine-tuning. We
illustrate our idea by considering a model of scalar gravity with
Horava-Lifshitz scaling coupled to a supersymmetric Wess-Zumino matter sector,
in which we compute the two-loop SUSY breaking corrections to the masses of the
light scalars due to the gravitational interactions and the heavy fields.


title: Characterizing Jordan derivations of matrix rings through zero products

abstract:
  Let $\Mn$ be the ring of all $n \times n$ matrices over a unital ring
$\mathcal{R}$, let $\mathcal{M}$ be a 2-torsion free unital $\Mn$-bimodule and
let $D:\Mn\rightarrow \mathcal{M}$ be an additive map. We prove that if
$D(\A)\B+ \A D(\B)+D(\B)\A+ \B D(\A)=0$ whenever $\A,\B\in \Mn$ are such that
$\A\B=\B\A=0$, then $D(\A)=\delta(\A)+\A D(\textbf{1})$, where
$\delta:\Mn\rightarrow \mathcal{M}$ is a derivation and $D(\textbf{1})$ lies in
the centre of $\mathcal{M}$. It is also shown that $D$ is a generalized
derivation if and only if $D(\A)\B+ \A D(\B)+D(\B)\A+ \B D(\A)-\A
D(\textbf{1})\B-\B D(\textbf{1})\A=0$ whenever $\A\B=\B\A=0$. We apply this
results to provide that any (generalized) Jordan derivation from $\Mn$ into a
2-torsion free $\Mn$-bimodule (not necessarily unital) is a (generalized)
derivation. Also, we show that if $\varphi:\Mn\rightarrow \Mn$ is an additive
map satisfying $\varphi(\A \B+\B \A)=\A\varphi(\B)+\varphi(\B)\A \quad (\A,\B
\in \Mn)$, then $\varphi(\A)=\A\varphi(\textbf{1})$ for all $\A\in \Mn$, where
$\varphi(\textbf{1})$ lies in the centre of $\Mn$. By applying this result we
obtain that every Jordan derivation of the trivial extension of $\Mn$ by $\Mn$
is a derivation.


title:
The density matrix renormalization group algorithm on kilo-processor
  architectures: implementation and trade-offs

abstract:
  In the numerical analysis of strongly correlated quantum lattice models one
of the leading algorithms developed to balance the size of the effective
Hilbert space and the accuracy of the simulation is the density matrix
renormalization group (DMRG) algorithm, in which the run-time is dominated by
the iterative diagonalization of the Hamilton operator. As the most
time-dominant step of the diagonalization can be expressed as a list of dense
matrix operations, the DMRG is an appealing candidate to fully utilize the
computing power residing in novel kilo-processor architectures. In the paper a
smart hybrid CPU-GPU implementation is presented, which exploits the power of
both CPU and GPU and tolerates problems exceeding the GPU memory size.
Furthermore, a new CUDA kernel has been designed for asymmetric matrix-vector
multiplication to accelerate the rest of the diagonalization. Besides the
evaluation of the GPU implementation, the practical limits of an FPGA
implementation are also discussed.


title: Geometrically closed rings

abstract:
  We develop the basic theory of geometrically closed rings as a generalisation
of algebraically closed fields, on the grounds of notions coming from positive
model theory and affine algebraic geometry. For this purpose we consider
several connections between finitely presented rings and ultraproducts, affine
varieties and definable sets, and we introduce the key notion of an arithmetic
theory as a purely algebraic version of coherent logic for rings.


title:
Ferromagnetism in the one-dimensional Kondo lattice: mean-field approach
  via Majorana fermion canonical transformation

abstract:
  Using a canonical transformation it is possible to faithfully represent the
Kondo lattice model in terms of Majorana fermions. Studying this representation
we discovered an exact mapping between the Kondo lattice Hamiltonian and a
Hamiltonian describing three spinless fermions interacting on a lattice. We
investigate the effectiveness of this three fermion representation by
performing a zero temperature mean-field study of the phase diagram at
different couplings and fillings for the one-dimensional case, focusing on the
appearance of ferromagnetism. The solutions agree in many respects with the
known numerical and analytical results. In particular, in the ferromagnetic
region connected to the solution at zero electron density, we have a
quantitative agreement on the value of the commensurability parameter
discovered in recent DMRG (in one dimension) and DMFT (in infinite dimensions)
simulations; furthermore we provide a theoretical justification for it,
identifying a symmetry of the Hamiltonian. This ferromagnetic phase is
stabilized by the emergence of a spin-selective Kondo insulator that is
described quite conveniently by the three spinless fermions. We discovered also
a different ferromagnetic phase at high filling and low couplings. This phase
resembles the RKKY ferromagnetic phase existing at vanishing filling, but it
incorporates much more of the Kondo effect, making it energetically more
favorable than the typical spiral (spin ordered) mean field ground states. We
believe that this second phase represents a prototype for the strange
ferromagnetic tongue identified by numerical simulations inside the
paramagnetic dome. At the end of the work we also provide a discussion of
possible orders different from the ferromagnetic one. In particular at
half-filling, where we obtain as ground state at high coupling the correct
Kondo insulating state.


title:
Image-guided therapy system for interstitial gynecologic brachytherapy
  in a multimodality operating suite

abstract:
  In this contribution, an image-guided therapy system supporting gynecologic
radiation therapy is introduced. The overall workflow of the presented system
starts with the arrival of the patient and ends with follow-up examinations by
imaging and a superimposed visualization of the modeled device from a PACS
system. Thereby, the system covers all treatments stages (pre-, intra- and
postoperative) and has been designed and constructed by a computer scientist
with feedback from an interdisciplinary team of physicians and engineers. This
integrated medical system enables dispatch of diagnostic images directly after
acquisition to a processing workstation that has an on-board 3D Computer Aided
Design model of a medical device. Thus, allowing precise identification of
catheter location in the 3D imaging model which later provides rapid feedback
to the clinician regarding device location. Moreover, the system enables the
ability to perform patient-specific pre-implant evaluation by assessing the
placement of interstitial needles prior to an intervention via virtual template
matching with a diagnostic scan.


title:
OCTBEC - A Matlab toolbox for optimal quantum control of Bose-Einstein
  condensates

abstract:
  OCTBEC is a Matlab toolbox designed for optimal quantum control, within the
framework of optimal control theory (OCT), of Bose-Einstein condensates (BEC).
The systems we have in mind are ultracold atoms in confined geometries, where
the dynamics takes place in one or two spatial dimensions, and the confinement
potential can be controlled by some external parameters. Typical experimental
realizations are atom chips, where the currents running through the wires
produce magnetic fields that allow to trap and manipulate nearby atoms. The
toolbox provides a variety of Matlab classes for simulations based on the
Gross-Pitaevskii equation, the multi-configurational Hartree method for bosons,
and on generic few-mode models, as well as optimization problems. These classes
can be easily combined, which has the advantage that one can adapt the
simulation programs flexibly for various applications.


title:
Existence and concentration of positive bound states for the
  Schr\"odinger-Poisson system with potentials

abstract:
  In this article we study the existence and concentration behavior of bound
states for a nonlinear Schr\"odinger-Poisson system with a parameter
$\varepsilon>0$. Under some suitable conditions on the potential functions, we
prove that for $\varepsilon$ small the system has a positive solution that
concentrates at a point which is a global minimum of the minimax function
associated to the related autonomous problem.