title:
3D Simulation of Dam-break effect on a Solid Wall using Smoothed
  Particle Hydrodynamics

abstract:
  Dam is built for water supply, water flow or flooding control and electricity
energy storage, but in other hand, dam is one of the most dangerous natural
disaster in many countries including in Indonesia. The impact of dam break in
neighbour area and is huge and many flooding in remote area, as happen in Dam
Situ Gintung in Tangerang (close to Jakarta) in 2009. Smoothed Particle
Hydrodynamics (SPH), is one of numerical method based on Lagrangian grid which
is ap- plied in astrophysical simulation may be used to solve the simulation on
dam break effect. The development of SPH methods become alternative methods to
solving Navier Stokes equation, which is main key in fluid dynamic simulation.
In this paper, SPH is developed for supporting solid par- ticles in use for 3D
dam break effect (3D-DBE) simulation. Solid particle have been treated same as
fluid particles with additional calculation for converting gained position
became translation and rotation of solid object in a whole body. With this
capability, the result of 3D-DBE simulation has been varies and interesting.
The goals of this simulation is for analyse fluid and solid particle
interaction by using two different scenario. The first scenario relation
between height of fluid to a solid wall barrier and second scenario, is to
study relation between solid wall and its collapse time by dam break. The
results show sliding distance of a solid wall is depend on a fluid height, and
relation between fluid heght and wall dimension will be discussed too in this
paper.


title:
On the construction of a psychologically based, general theory of
  observation: an introduction

abstract:
  The perception-related origins of physical measures and standards are
considered within the framework of the general observer theory. The impact of
observer characteristics on the development of observer-centric physics,
physical concepts and metrics are analyzed. A preliminary theoretical approach
is suggested for the construction of a general observer theory and formulation
of its relationship to observer-centered physical concepts and theories. The
approach makes it possible to construct a theory of the observer, intrinsic in
any theory of physics.


title:
Atomic scale investigation of grain boundary structure role on
  deformation and crack growth dynamics in Aluminum

abstract:
  The role that grain boundary (GB) structure plays on the plasticity of
interfaces with preexisting cracks and on the interface crack dynamics was
investigated using MD for both <100> and <110> aluminum STGBs. In simulations
with a crack at the interface, this research shows how the maximum normal
strength of the interface correlates with the respective GB energy, the GB
misorientation, and the GB structural description. For instance, the normal
interface strength for GBs containing D structural unit (SU) or stacking faults
in the GB structural description ({\Sigma}13 (510) {\theta}=22.6{\deg} and
{\Sigma}97 (940) {\theta}=47.9{\deg}) shows a noticeable decrease in interface
strength, as compared to other evaluated <100> GBs that contained favored SUs.
In the case of <110> interfaces, the presence of the E SU in the GB structure
lowers the maximum normal interface strength by 35%. Further investigation of
the deformation at the crack tip in GBs containing the E structure revealed
that the E SU underwent atomic shuffling to accommodate intrinsic stacking
faults (ISFs) along the interface, which in turn acts as a site for partial
dislocation nucleation. Interestingly, regardless of GB misorientation, GB
interfaces examined here containing the E structure in their structural period
exhibited relatively small variation in maximum normal strength of interface.
The GB volume ahead of the crack tip underwent structural rearrangement which,
in turn, influenced the crack propagation mechanism. In most GBs, the crack
propagation was due to alternating mechanisms of dislocation emission, followed
by propagation of dislocation (blunting) and cleavage/crack advance. Moreover,
the crack growth rates along the GB interface were strongly influenced by the
initial free volume at the interface, i.e., faster crack growth was observed
along interfaces with higher initial free volume.


title: Computer simulation of two-mode nonlinear quantum scissors

abstract:
  We present a simulation method allowing for modeling of quantum dynamics of
nonlinear quantum scissors' (NQS) systems. We concentrate on the two-mode model
involving two mutually interacting nonlinear quantum oscillators (Kerr
nonlinear coupler) excited by a series of ultra-short external coherent pulses.
We show that despite the simplicity of the method one can obtain non-trivial
results. In particular, we discuss and compare two cases of kicked nonlinear
coupler, showing that the quantum evolution of the system remains closed within
a two-qubit Hilbert space and can lead to maximally entangled states
generation.


title: Strongly productive ultrafilters on semigroups

abstract:
  We prove that if S is a commutative semigroup with well founded universal
semilattice or a solvable inverse semigroup with well founded semilattice of
idempotents, then every strongly productive ultrafilter on S is idempotent.
Moreover we show that any very strongly productive ultrafilter on the free
semigroup with countably many generators is sparse, answering a question of
Hindman and Legette Jones.


title:
Nanotribology of biopolymer brushes in aqueous solution using
  dissipative particle dynamics simulations: an application to PEG covered
  liposomes in theta solvent

abstract:
  We undertake the investigation of sheared polymer chains grafted on flat
surfaces to model liposomes covered with polyethylene glycol brushes as a case
study for the mechanisms of efficient drug delivery in biologically relevant
situations, for example, as carriers for topical treatments of illnesses in the
human vasculature. For these applications, specific rheological properties are
required, such as low viscosity at high shear rate to improve the transport of
the liposomes. Therefore non - equilibrium, DPD simulations of polymer brushes
of various length and shear rates are performed to obtain the average viscosity
and friction coefficient of the system as functions of the shear rate and
polymerization degree under theta solvent conditions, and find that the brushes
experience shear thinning at large shear rates.The viscosity and the friction
coefficient are shown to obey scaling laws at high shear rate in theta solvent,
irrespective of the brushes degree of polymerization. These results confirm
recent scaling predictions and reproduce very well trends in measurements of
the viscosity at high shear of red blood cells in a liposome containing medium.


title: Introductory lectures to large-N QCD phenomenology and lattice results

abstract:
  An elementary, pedagogical introduction to the large-N limit of QCD and to
its phenomenological implications is presented, and a survey of lattice results
in the 't Hooft limit is briefly discussed.


title: Reducing Financial Avalanches By Random Investments

abstract:
  Building on similarities between earthquakes and extreme financial events, we
use a self-organized criticality-generating model to study herding and
avalanche dynamics in financial markets. We consider a community of interacting
investors, distributed on a small-world network, who bet on the bullish
(increasing) or bearish (decreasing) behavior of the market which has been
specified according to the S&P500 historical time series. Remarkably, we find
that the size of herding-related avalanches in the community can be strongly
reduced by the presence of a relatively small percentage of traders, randomly
distributed inside the network, who adopt a random investment strategy. Our
findings suggest a promising strategy to limit the size of financial bubbles
and crashes. We also obtain that the resulting wealth distribution of all
traders corresponds to the well-known Pareto power law, while the one of random
traders is exponential. In other words, for technical traders, the risk of
losses is much greater than the probability of gains compared to those of
random traders.


title:
Estimating Potential Infection Transmission Routes in Hospital Wards
  Using Wearable Proximity Sensors

abstract:
  Contacts between patients, patients and health care workers (HCWs) and among
HCWs represent one of the important routes of transmission of hospital-acquired
infections (HAI). A detailed description and quantification of contacts in
hospitals provides key information for HAIs epidemiology and for the design and
validation of control measures. We used wearable sensors to detect close-range
interactions ("contacts") between individuals in the geriatric unit of a
university hospital. Contact events were measured with a spatial resolution of
about 1.5 meters and a temporal resolution of 20 seconds. The study included 46
HCWs and 29 patients and lasted for 4 days and 4 nights. 14037 contacts were
recorded. The number and duration of contacts varied between mornings,
afternoons and nights, and contact matrices describing the mixing patterns
between HCW and patients were built for each time period. Contact patterns were
qualitatively similar from one day to the next. 38% of the contacts occurred
between pairs of HCWs and 6 HCWs accounted for 42% of all the contacts
including at least one patient, suggesting a population of individuals who
could potentially act as super-spreaders. Wearable sensors represent a novel
tool for the measurement of contact patterns in hospitals. The collected data
provides information on important aspects that impact the spreading patterns of
infectious diseases, such as the strong heterogeneity of contact numbers and
durations across individuals, the variability in the number of contacts during
a day, and the fraction of repeated contacts across days. This variability is
associated with a marked statistical stability of contact and mixing patterns
across days. Our results highlight the need for such measurement efforts in
order to correctly inform mathematical models of HAIs and use them to inform
the design and evaluation of prevention strategies.


title: Optical properties of 2D magnetoelectric point scattering lattices

abstract:
  We explore the electrodynamic coupling between a plane wave and an infinite
two-dimensional periodic lattice of magneto-electric point scatterers, deriving
a semi-analytical theory with consistent treatment of radiation damping,
retardation, and energy conservation. We apply the theory to arrays of split
ring resonators and provide a quantitive comparison of measured and calculated
transmission spectra at normal incidence as a function of lattice density,
showing excellent agreement. We further show angle-dependent transmission
calculations for circularly polarized light and compare with the
angle-dependent response of a single split ring resonator, revealing the
importance of cross coupling between electric dipoles and magnetic dipoles for
quantifying the pseudochiral response under oblique incidence of split ring
lattices.


title:
An Alternate method to find the chromatic number of a Finite, Connected
  Graph

abstract:
  A new algorithm to obtain the chromatic number of a finite, connected graph
is proposed in this paper. The algorithm is based on contraction of non
adjacent vertices.


title:
Theoretical thermodynamic analysis of a closed-cycle process for the
  conversion of heat into electrical energy by means of a distiller and an
  electrochemical cell

abstract:
  We analyse a device aimed at the conversion of heat into electrical energy,
based on a closed cycle in which a distiller generates two solutions at
different concentrations, and an electrochemical cell consumes the
concentration difference, converting it into electrical current. We first study
an ideal model of such a process. We show that, if the device works at a single
fixed pressure (i.e. with a ``single effect''), then the efficiency of the
conversion of heat into electrical power can approach the efficiency of a
reversible Carnot engine operating between the boiling temperature of the
concentrated solution and that of the pure solvent. When two heat reservoirs
with a higher temperature difference are available, the overall efficiency can
be incremented by employing an arrangement of multiple cells working at
different pressures (``multiple effects''). We find that a given efficiency can
be achieved with a reduced number of effects by using solutions with a high
boiling point elevation.


title:
On the asymptotic Plateau's problem for CMC hypersurfaces in hyperbolic
  space

abstract:
  It is extended a result due to B. Guan and J. Spruck on the asymptotic
Plateau's problem for CMC radial graphs in hyperbolic space to horizontal CMC
graphs.


title: Entropy of random graph ensembles constrained with generalised degrees

abstract:
  Generalised degrees provide a natural bridge between local and global
topological properties of networks. We define the generalised degree to be the
number of neighbours of a node within one and two steps respectively. Tailored
random graph ensembles are used to quantify and compare topological properties
of networks in a systematic and precise manner, using concepts from information
theory. We calculate the Shannon entropy of random graph ensembles constrained
with a specified generalised degree distribution. We find that the outcome has
a natural connection with the degree-degree correlation which is implied by
specifying a generalised degree distribution. We demonstrate how generalised
degrees can be used to qualitatively and quantitatively describe a network.


title:
Input-output description of microwave radiation in the dynamical Coulomb
  blockade

abstract:
  We study microwave radiation emitted by a small voltage-biased Josephson
junction connected to a superconducting transmission line. An input-output
formalism for the radiation field is established, using a perturbation
expansion in the junction's critical current. Using output field operators
solved up to the second order, we estimate the spectral density and the
second-order coherence of the emitted field. For typical transmission line
impedances and at frequencies below the main emission peak at the Josephson
frequency, radiation occurs predominantly due to two-photon emission. This
emission is characterized by a high degree of photon bunching if detected
symmetrically around half of the Josephson frequency. Strong phase fluctuations
in the transmission line make related nonclassical phase-dependent amplitude
correlations short lived, and there is no steady-state two-mode squeezing.
However, the radiation is shown to violate the classical Cauchy-Schwarz
inequality of intensity cross-correlations, demonstrating the nonclassicality
of the photon pair production in this region.


title: Protecting Public OSN Posts from Unintended Access

abstract:
  The design of secure and usable access schemes to personal data represent a
major challenge of online social networks (OSNs). State of the art requires
prior interaction to grant access. Sharing with users who are not subscribed or
previously have not been accepted as contacts in any case is only possible via
public posts, which can easily be abused by automatic harvesting for user
profiling, targeted spear-phishing, or spamming. Moreover, users are restricted
to the access rules defined by the provider, which may be overly restrictive,
cumbersome to define, or insufficiently fine-grained.
  We suggest a complementary approach that can be easily deployed in addition
to existing access control schemes, does not require any interaction, and
includes even public, unsubscribed users. It exploits the fact that different
social circles of a user share different experiences and hence encrypts
arbitrary posts. Hence arbitrary posts are encrypted, such that only users with
sufficient knowledge about the owner can decrypt.
  Assembling only well-established cryptographic primitives, we prove that the
security of our scheme is determined by the entropy of the required knowledge.
We consequently analyze the efficiency of an informed dictionary attack and
assess the entropy to be on par with common passwords. A fully functional
implementation is used for performance evaluations, and available for download
on the Web.


title: Towards Conformal Capacities in Euclidean Spaces

abstract:
  This paper addresses the so-called conformal capacities in $\mathbb R^n$,
$n\ge 3$, through comparing three existing definitions (due to Betsakos,
Colesanti-Cuoghi, Anderson-Vamananmurthy-Fuglede respectively) and studying
their associated iso-capacitary inequalities with connection to half-diameter,
mean-width, mean-curvature and ADM-mass, Hadamard type variational formula,
Minkowski type problem, and Yau type problem.


title:
Adjoint-Based Error Estimation and Mesh Adaptation for Hybridized
  Discontinuous Galerkin Methods

abstract:
  We present a robust and efficient target-based mesh adaptation methodology,
building on hybridized discontinuous Galerkin schemes for (nonlinear)
convection-diffusion problems, including the compressible Euler and
Navier-Stokes equations. Hybridization of finite element discretizations has
the main advantage, that the resulting set of algebraic equations has globally
coupled degrees of freedom only on the skeleton of the computational mesh.
Consequently, solving for these degrees of freedom involves the solution of a
potentially much smaller system. This not only reduces storage requirements,
but also allows for a faster solution with iterative solvers. The mesh
adaptation is driven by an error estimate obtained via a discrete adjoint
approach. Furthermore, the computed target functional can be corrected with
this error estimate to obtain an even more accurate value. The aim of this
paper is twofold: Firstly, to show the superiority of adjoint-based mesh
adaptation over uniform and residual-based mesh refinement, and secondly to
investigate the efficiency of the global error estimate.


title: Symmetry, Isotopy, and Irregular Covers

abstract:
  We say that a cover of surfaces S -> X has the Birman--Hilden property if the
subgroup of the mapping class group of X consisting of mapping classes that
have representatives that lift to S embeds in the mapping class group of S
modulo the group of deck transformations. We identify one necessary condition
and one sufficient condition for when a cover has this property. We give new
explicit examples of irregular branched covers that do not satisfy the
necessary condition as well as explicit covers that satisfy the sufficient
condition. Our criteria are conditions on simple closed curves, and our proofs
use the combinatorial topology of curves on surfaces.


title: Damping of the quadrupole mode in a two-dimensional Fermi gas

abstract:
  In a recent experiment [E. Vogt et al., Phys. Rev. Lett. 108, 070404 (2012)],
quadrupole and breathing modes of a two-dimensional Fermi gas were studied. We
model these collective modes by solving the Boltzmann equation via the method
of phase-space moments up to fourth order, including in-medium effects on the
scattering cross section. In our analysis, we use a realistic Gaussian
potential deformed by the presence of gravity and magnetic field gradients. We
conclude that the origin of the experimentally observed damping of the
quadrupole mode, especially in the weakly interacting (or even non-interacting)
case, cannot be explained by these mechanisms.


title:
Precise mass and spin measurements for a stellar-mass black hole through
  X-ray timing: the case of GRO J1655-40

abstract:
  We present a systematic analysis of the fast time variability properties of
the transient black hole binary GRO J1655-40, based on the complete set of
RossiXTE observations. We demonstrate that the frequencies of the
quasi-periodic oscillations and of the broad band noise components and their
variations match accurately the strong field general relativistic frequencies
of particle motion in the close vicinity of the innermost stable circular
orbit, as predicted by the relativistic precession model. We obtain high
precision measurements of the black hole mass (M = (5.31 +/- 0.07) M solar
masses, consistent with the value from optical/NIR observations) and spin (a/M
= 0.290 +/- 0.003), through the sole use of X-ray timing.


title:
Excellent magnetocaloric effect exhibited in the dense inorganic
  framework material Gd(OH)CO3

abstract:
  The excellent magnetocaloric effect of a dense inorganic framework,
orthorhombic Gd(OH)CO3, is evaluated by isothermal magnetization and heat
capacity measurements. The large -{\Delta}Sm, both in gravimetric and
volumetric units, place it as a great candidate for cryogenic magnetic cooler.


title: Plasmons in graphene: Recent progress and applications

abstract:
  Owing to its excellent electrical, mechanical, thermal and optical
properties, graphene has attracted great interests since it was successfully
exfoliated in 2004. Its two dimensional nature and superior properties meet the
need of surface plasmons and greatly enrich the field of plasmonics. Recent
progress and applications of graphene plasmonics will be reviewed, including
the theoretical mechanisms, experimental observations, and meaningful
applications. With relatively low loss, high confinement, flexible feature, and
good tunability, graphene can be a promising plasmonic material alternative to
the noble metals. Optics transformation, plasmonic metamaterials, light
harvesting etc. are realized in graphene based devices, which are useful for
applications in electronics, optics, energy storage, THz technology and so on.
Moreover, the fine biocompatibility of graphene makes it a very well candidate
for applications in biotechnology and medical science.


title: Dead Zone Penetration Protocol for Cognitive Radio Networks

abstract:
  Current routing protocols for cognitive radio networks are severely affected
by the frequent activity of primary users. Nodes that are in the interference
range of an appearing primary user are not allowed to transmit, and therefore
existing routes which utilize such nodes are obliged to undergo a route
maintenance phase. This naturally provides other routes to the destination that
may incur extra delay or increase packet queuing overhead. In this work, a
novel route maintenance protocol is proposed that allows existing routes to
endure the event of primary user presence by forming cooperative links between
neighboring nodes and nulling out transmission at the primary receiver using
cooperative beamforming. Our proposed protocol can be used in conjunction with
any of the existing routing protocols, thus achieving modularity. Extensive
simulations are done which prove that our proposed protocol outperforms
existing route maintenance techniques in terms of end-to-end delay and loss
ratio, with minimal incurred overhead.


title: Lineability criteria, with applications

abstract:
  Lineability is a property enjoyed by some subsets within a vector space X. A
subset A of X is called lineable whenever A contains, except for zero, an
infinite dimensional vector subspace. If, additionally, X is endowed with
richer structures, then the more stringent notions of dense-lineability,
maximal dense-lineability and spaceability arise naturally. In this paper,
several lineability criteria are provided and applied to specific topological
vector spaces, mainly function spaces. Sometimes, such criteria furnish unified
proofs of a number of scattered results in the related literature. Families of
strict-order integrable functions, hypercyclic vectors, non-extendable
holomorphic mappings, Riemann non-Lebesgue integrable functions, sequences not
satisfying the Lebesgue dominated convergence theorem, nowhere analytic
functions, bounded variation functions, entire functions with fast growth and
Peano curves, among others, are analyzed from the point of view of lineability.


title: A counterexample to a theorem of Bremermann on Shilov boundaries

abstract:
  We give a counterexample to the following theorem of Bremermann on Shilov
boundaries: if $D$ is a bounded domain in $\mathbb C^n$ having a univalent
envelope of holomorphy, say $\widetilde D$, then the Shilov boundary of $D$
with respect to the algebra $\mathcal A(D)$ coincides with the corresponding
one for $\widetilde D$.


title: Parallel DNA Synthesis : Two PCR product from one DNA template

abstract:
  Conventionally in a PCR reaction, Primers binds to DNA template in an
antiparallel manner and template DNA is amplified as it is. Here we describe an
approach in which First primer binds in a complementary parallel orientation
leading to synthesis in parallel direction. Further reaction happened in usual
way leading to synthesis of final DNA product having opposite polarity then the
template used. We first time proved that synthesis of DNA can happen in a
parallel orientation. We first time have shown that from a single DNA template,
Two different related PCR products can be synthesized.


title:
Use of the Basset coefficient in the calculation of the velocity of a
  spheroid slowing down in a viscous incompressible fluid after a sudden
  impulse

abstract:
  The motion of a spheroid in a viscous incompressible fluid after a sudden
small impulse in the direction of the symmetry axis is studied on the basis of
the linearized Navier-Stokes equations. The time-dependence of the spheroid
velocity follows by a Fourier transform from the frequency- dependence of the
impedance involving friction coefficient, body mass, and added fluid mass. A
term proportional to the square root of frequency in the asymptotic high
frequency expansion of the impedance, with a Basset coefficient, describes the
initial decay in time from the initial value determined by the effective mass.
It is shown from numerical evidence based on the exact multipole expansion of
the solution for the flow field in terms of spheroidal wavefunctions that the
knowledge of the Basset coefficient is insufficient for a reliable estimate of
the deviations from a simple two-pole approximation to the complete behavior in
time. The two-pole approximation can be calculated from the effective mass and
the steady state friction coefficient.


title:
(Failure of the) Wisdom of the crowds in an endogenous opinion dynamics
  model with multiply biased agents

abstract:
  We study an endogenous opinion (or, belief) dynamics model where we
endogenize the social network that models the link (`trust') weights between
agents. Our network adjustment mechanism is simple: an agent increases her
weight for another agent if that agent has been close to truth (whence, our
adjustment criterion is `past performance'). Moreover, we consider multiply
biased agents that do not learn in a fully rational manner but are subject to
persuasion bias - they learn in a DeGroot manner, via a simple `rule of thumb'
- and that have biased initial beliefs. In addition, we also study this setup
under conformity, opposition, and homophily - which are recently suggested
variants of DeGroot learning in social networks - thereby taking into account
further biases agents are susceptible to. Our main focus is on crowd wisdom,
that is, on the question whether the so biased agents can adequately aggregate
dispersed information and, consequently, learn the true states of the topics
they communicate about. In particular, we present several conditions under
which wisdom fails.


title:
Message passing and moment closure for susceptible-infected-recovered
  epidemics on finite networks

abstract:
  The message passing approach of Karrer and Newman [Phys. Rev. E 82, 016101
(2010)] is an exact and practicable representation of
susceptible-infected-recovered dynamics on finite trees. Here we show that,
assuming Poisson contact processes, a pair-based moment closure representation
[Sharkey, J. Math. Biol. 57, 311 (2008)] can be derived from their equations.
We extend the applicability of both representations and discuss their relative
merits. On arbitrary time-independent networks, as was shown for the message
passing formalism, the pair-based moment closure equations also provide a
rigorous lower bound on the expected number of susceptibles at all times.


title:
Derivation of the Love equation for the charge density of a circular
  plate condenser

abstract:
  The electrostatic problem of two coaxial parallel charged disks of different
radii in infinite space is solved by expansion in terms of complex potentials.
For perfectly conducting disks a pair of coupled integral equations is derived
for the two weight functions of the expansion. The weight function on each disk
is linearly related to its radially symmetric charge density. If the radii are
equal and the disks are oppositely charged the pair of equations reduce to
Love's integral equation for the circular plate condenser.


title:
An Elementary Derivation of the Large Deviation Rate Function for Finite
  State Markov Chains

abstract:
  Large deviation theory is a branch of probability theory that is devoted to a
study of the "rate" at which empirical estimates of various quantities converge
to their true values. The object of study in this paper is the rate at which
estimates of the doublet frequencies of a Markov chain over a finite alphabet
converge to their true values. In case the Markov process is actually an
i.i.d.\ process, the rate function turns out to be the relative entropy (or
Kullback-Leibler divergence) between the true and the estimated probability
vectors. This result is a special case of a very general result known as
Sanov's theorem and dates back to 1957. Moreover, since the introduction of the
"method of types" by Csisz\'{a}r and his co-workers during the 1980s, the proof
of this version of Sanov's theorem has been "elementary," using some
combinatorial arguments. However, when the i.i.d.\ process is replaced by a
Markov process, the available proofs are far more complex. The main objective
of this paper is therefore to present a first-principles derivation of the LDP
for finite state Markov chains, using only simple combinatorial arguments
(e.g.\ the method of types), thus gathering in one place various arguments and
estimates that are scattered over the literature.


title: Algebras simple with respect to a Sweedler's algebra action

abstract:
  Algebras simple with respect to an action of Sweedler's algebra $H_4$ deliver
the easiest example of $H$-module algebras that are $H$-simple but not
necessarily semisimple. We describe finite dimensional $H_4$-simple algebras
and prove the analog of Amitsur's conjecture for codimensions of their
polynomial $H_4$-identities. In particular, we show that the Hopf PI-exponent
of an $H_4$-simple algebra $A$ over an algebraically closed field of
characteristic $0$ equals $\dim A$. The groups of automorphisms preserving the
structure of an $H_4$-module algebra are studied as well.


title: Shellable drawings and the cylindrical crossing number of $K_n$

abstract:
  The Harary-Hill Conjecture States that the number of crossings in any drawing
of the complete graph $ K_n $ in the plane is at least
$Z(n):=\frac{1}{4}\left\lfloor \frac{n}{2}\right\rfloor
\left\lfloor\frac{n-1}{2}\right\rfloor \left\lfloor
\frac{n-2}{2}\right\rfloor\left\lfloor \frac{n-3}{2}\right\rfloor$. In this
paper, we settle the Harary-Hill conjecture for {\em shellable drawings}. We
say that a drawing $D$ of $ K_n $ is {\em $ s $-shellable} if there exist a
subset $ S = \{v_1,v_2,\ldots,v_ s\}$ of the vertices and a region $R$ of $D$
with the following property: For all $1 \leq i < j \leq s$, if $D_{ij}$ is the
drawing obtained from $D$ by removing $v_1,v_2,\ldots
v_{i-1},v_{j+1},\ldots,v_{s}$, then $v_i$ and $v_j$ are on the boundary of the
region of $D_{ij}$ that contains $R$. For $ s\geq n/2 $, we prove that the
number of crossings of any $ s $-shellable drawing of $ K_n $ is at least the
long-conjectured value Z(n). Furthermore, we prove that all cylindrical, $ x
$-bounded, monotone, and 2-page drawings of $ K_n $ are $ s $-shellable for
some $ s\geq n/2 $ and thus they all have at least $ Z(n) $ crossings. The
techniques developed provide a unified proof of the Harary-Hill conjecture for
these classes of drawings.


title: Periodic solutions in a seasonally forced epidemic model

abstract:
  We study an SIR epidemic model with a seasonal contact rate and saturated
treatment function. It is shown that the basic reproduction number $(\mathcal
{R}_0)$ cannot be acted as a threshold that predicts the spread of an
infection. Based on this finding, we establish a set of sufficient conditions
for the existence of multiple positive periodic solutions by using
Gaines-Mawhin's continuation theorem. This is very similar to backward
bifurcation for an autonomous model. Further, we investigate the stability of
positive periodic solution under small seasonal perturbation by means of
Floquet theory. Numerical simulations support our theoretical analysis.


title:
Variational description of Gibbs-non-Gibbs dynamical transitions for
  spin-flip systems with a Kac-type interaction

abstract:
  We continue our study of Gibbs-non-Gibbs dynamical transitions. In the
present paper we consider a system of Ising spins on a large discrete torus
with a Kac-type interaction subject to an independent spin-flip dynamics
(infinite-temperature Glauber dynamics). We show that, in accordance with the
program outlined in \cite{vEFedHoRe10}, in the thermodynamic limit
Gibbs-non-Gibbs dynamical transitions are \emph{equivalent} to bifurcations in
the set of global minima of the large-deviation rate function for the
trajectories of the empirical density \emph{conditional} on their endpoint.
More precisely, the time-evolved measure is non-Gibbs if and only if this set
is not a singleton for \emph{some} value of the endpoint. A partial description
of the possible scenarios of bifurcation is given, leading to a
characterization of passages from Gibbs to non-Gibbs and vice versa, with sharp
transition times.
  Our analysis provides a conceptual step-up from our earlier work on
Gibbs-non-Gibbs dynamical transitions for the Curie-Weiss model, where the
mean-field interaction allowed us to focus on trajectories of the empirical
magnetization rather than the empirical density.


title:
Convergence of the complete electromagnetic fluid system to the full
  compressible magnetohydrodynamic equations

abstract:
  The full compressible magnetohydrodynamic equations can be derived formally
from the complete electromagnetic fluid system in some sense as the dielectric
constant tends to zero. This process is usually referred as magnetohydrodynamic
approximation in physical books. In this paper we justify this singular limit
rigorously in the framework of smooth solutions for well-prepared initial data.


title: On the number of even and odd strings along the over partitions of n

abstract:
  Recently, Andrews, Chan, Kim and Osburn introduced the even strings and the
odd strings in the overpartitions. We show that their conjecture $A_k (n) \geq
B_k (n)$ holds for large enough positive integers n, where A_k(n) (resp.
B_k(n)) is the number of odd (resp. even) strings along the overpartitions of
n. We introduce m-strings and show that how this new combinatorial object is
related with another positivity conjecture of Andrews, Chan, Kim, and Osburn.
Finally, we confirm that the positivity conjecture is also true for large
enough integers.


title:
Localized states in the Mott insulator \kappa-(BEDT-TTF)_2Cu[N(CN)_2]Cl
  as probed by photoluminescence

abstract:
  We compare the photoluminescence spectra of the low-temperature Mott
insulator \etcl (T_{MIT}=40 K) with spectra of metallic
\kappa-(BEDT-TTF)_2Cu[N(CN)_2]Br, which is superconducting below T_c=11.8 K, in
the temperature range between 300 and 20 K. In the Mott insulating state of
\kappa-(BEDT-TTF)_2Cu[N(CN)_2]Cl we observe a luminescence band at 1.95 eV due
to the recombination of an exciton created by a HOMO-LUMO optical excitation.
This luminescence is quenched both in the high-temperature bad metal state of
\kappa-(BEDT-TTF)_2Cu[N(CN)_2]Cl and in metallic
\kappa-(BEDT-TTF)_2Cu[N(CN)_2]Br. The observation of the luminescence of an
exciton provides evidence for the local character of excitations in the Mott
insulating state.


title: Conformal Symmetries of FRW Accelerating Cosmologies

abstract:
  We show that any accelerating Friedmann-Robertson-Walker (FRW) cosmology with
equation of state w < -1/3 (and therefore not only a de Sitter stage with w
=-1) exhibits three-dimensional conformal symmetry on future constant-time
hypersurfaces. We also offer an alternative derivation of this result in terms
of conformal Killing vectors and show that long wavelength comoving curvature
perturbations of the perturbed FRW metric are just conformal Killing motions of
the FRW background. We then extend theb boundary conformal symmetry to the bulk
for accelerating cosmologies. Our findings indicate that one can easily
generate perturbations of scalar fields which are not only scale invariant, but
also fully conformally invariant on super-Hubble scales. Measuring a
scale-invariant power spectrum for the cosmological perturbation does not
automatically imply that the universe went through a de Sitter stage.


title:
Suzaku observations of the type 2 QSO in the central galaxy of the
  Phoenix cluster

abstract:
  We report the \Suzaku/XIS and HXD and \Chandra/ACIS-I results on the X-ray
spectra of the Phoenix cluster at the redshift $z=0.596$. The spectrum of the
intracluster medium (ICM) is well-reproduced with the emissions from a low
temperature ($\sim3.0$\,keV and $\sim0.76$\,solar) and a high temperature
($\sim11$\,keV and $\sim0.33$\,solar) plasmas; the former is localized at the
cluster core, while the latter distributes over the cluster. In addition to
these ICM emissions, a strongly absorbed power-law component is found, which is
due to an active galactic nucleus (AGN) in the cluster center. The absorption
column density and unobscured luminosity of the AGN are
$\sim3.2\times10^{23}$\,cm$^{-2}$ and $\sim4.7\times10^{45}$\,ergs\,s$^{-1}$
(2-10\,keV), respectively. Furthermore, a neutral iron (\ion{Fe}{1}) K-shell
line is discovered for the first time with the equivalent width (EW) of
$\sim150$\,eV at the rest frame. The column density and the EW of the
\ion{Fe}{1} line are exceptionally large for such a high luminosity AGN, and
hence the AGN is classified as a type 2 quasi-stellar object (QSO). We
speculate that the significant fraction of the ICM cooled gas would be consumed
to maintain the torus and to activate the type 2 QSO. The Phoenix cluster has a
massive starburst in the central galaxy, indicating suppression in the cooling
flow is less effective. This may be because the onset of the latest AGN
feedback has occurred recently and it has not yet been effective.
Alternatively, the AGN feedback is predominantly in radiative-mode not in
kinetic-mode and the torus may work as a shield to reduce its effect.


title:
Is there an algorithm which takes as input a Diophantine equation,
  returns an integer, and this integer is greater than the number of integer
  solutions, if the solution set is finite?

abstract:
  Let E_n={x_i=1, x_i+x_j=x_k, x_i \cdot x_j=x_k: i,j,k \in {1,...,n}}. For a
positive integer n, let f(n) denote the greatest finite total number of
solutions of a subsystem of E_n in integers x_1,...,x_n. We prove: (1) the
function f is strictly increasing, (2) if a non-decreasing function g from
positive integers to positive integers satisfies f(n) \geq g(n) for any n, then
a finite-fold Diophantine representation of g does not exist, (3) if the
question of the title has a positive answer, then there is a computable
strictly increasing function g from positive integers to positive integers such
that f(n) \leq g(n) for any n and a finite-fold Diophantine representation of g
does not exist.


title:
Power Allocation for Distributed BLUE Estimation with Full and Limited
  Feedback of CSI

abstract:
  This paper investigates the problem of adaptive power allocation for
distributed best linear unbiased estimation (BLUE) of a random parameter at the
fusion center (FC) of a wireless sensor network (WSN). An optimal
power-allocation scheme is proposed that minimizes the $L^2$-norm of the vector
of local transmit powers, given a maximum variance for the BLUE estimator. This
scheme results in the increased lifetime of the WSN compared to similar
approaches that are based on the minimization of the sum of the local transmit
powers. The limitation of the proposed optimal power-allocation scheme is that
it requires the feedback of the instantaneous channel state information (CSI)
from the FC to local sensors, which is not practical in most applications of
large-scale WSNs. In this paper, a limited-feedback strategy is proposed that
eliminates this requirement by designing an optimal codebook for the FC using
the generalized Lloyd algorithm with modified distortion metrics. Each sensor
amplifies its analog noisy observation using a quantized version of its optimal
amplification gain, which is received by the FC and used to estimate the
unknown parameter.


title:
Optimizing Maximum Flow Time and Maximum Throughput in Broadcast
  Scheduling

abstract:
  We consider the pull-based broadcast scheduling model. In this model, there
are n unit-sized pages of information available at the server. Requests arrive
over time at the server asking for a specific page. When the server transmits a
page, all outstanding requests for the page are simultaneously satisfied, and
this is what distinguishes broadcast scheduling from the standard scheduling
setting where each job must be processed separately by the server. Broadcast
scheduling has received a considerable amount of attention due to the
algorithmic challenges that it gives in addition to its applications in
multicast systems and wireless and LAN networks. In this paper, we give the
following new approximation results for two popular objectives:
  - For the objective of minimizing the maximum flow time, we give the first
PTAS. Previously, it was known that the algorithm First-In-First-Out (FIFO) is
a 2-approximation, and it is tight. It has been suggested as an open problem to
obtain a better approximation.
  - For the objective of maximizing the throughput, we give a
0.7759-approximation which improves upon the previous best known
0.75-approximation.
  Our improved results are enabled by our novel rounding schemes and linear
programming which can effectively reduce congestion in schedule which is often
the main bottleneck in designing scheduling algorithms based on linear
programming. We believe that our algorithmic ideas and techniques could be of
potential use for other scheduling problems.


title:
Optimized projections for compressed sensing via rank-constrained
  nearest correlation matrix

abstract:
  Optimizing the acquisition matrix is useful for compressed sensing of signals
that are sparse in overcomplete dictionaries, because the acquisition matrix
can be adapted to the particular correlations of the dictionary atoms. In this
paper a novel formulation of the optimization problem is proposed, in the form
of a rank-constrained nearest correlation matrix problem. Furthermore,
improvements for three existing optimization algorithms are introduced, which
are shown to be particular instances of the proposed formulation. Simulation
results show notable improvements and superior robustness in sparse signal
recovery.


title:
Characterizations of generalized poles by pole cancellation functions of
  higher order

abstract:
  In this paper the analytic characterization of generalized poles of operator
valued generalized Nevanlinna functions (including the length of Jordan chains
of the representing relation) is completed. In particular, given a Jordan chain
of length $\ell$, we show that there exists a pole cancellation function of
order at least $\ell$, and, moreover, this function is of surprisingly simple
form.


title:
Temporal quantum correlations and Leggett-Garg inequalities in
  multi-level systems

abstract:
  We show that the quantum bound for temporal correlations in a Leggett-Garg
test, analogous to the Tsirelson bound for spatial correlations in a Bell test,
strongly depends on the number of levels $N$ that can be accessed by the
measurement apparatus via projective measurements. We provide exact bounds for
small $N$, that exceed the known bound for the Leggett-Garg inequality, and
show that in the limit $N\rightarrow \infty$ the Leggett-Garg inequality can be
violated up to its algebraic maximum.


title:
Role of non-ideality for the ion transport in porous media: derivation
  of the macroscopic equations using upscaling

abstract:
  This paper is devoted to the homogenization (or upscaling) of a system of
partial differential equations describing the non-ideal transport of a
N-component electrolyte in a dilute Newtonian solvent through a rigid porous
medium. Realistic non-ideal effects are taken into account by an approach based
on the mean spherical approximation (MSA) model which takes into account finite
size ions and screening effects. We first consider equilibrium solutions in the
absence of external forces. In such a case, the velocity and diffusive fluxes
vanish and the equilibrium electrostatic potential is the solution of a variant
of Poisson-Boltzmann equation coupled with algebraic equations. Contrary to the
ideal case, this nonlinear equation has no monotone structure. However, based
on invariant region estimates for Poisson-Boltzmann equation and for small
characteristic value of the solute packing fraction, we prove existence of at
least one solution. To our knowledge this existence result is new at this level
of generality. When the motion is governed by a small static electric field and
a small hydrodynamic force, we generalize O'Brien's argument to deduce a
linearized model. Our second main result is the rigorous homogenization of
these linearized equations and the proof that the effective tensor satisfies
Onsager properties, namely is symmetric positive definite. We eventually make
numerical comparisons with the ideal case. Our numerical results show that the
MSA model confirms qualitatively the conclusions obtained using the ideal model
but there are quantitative differences arising that can be important at high
charge or high concentrations.


title: A new equilibrium torus solution and GRMHD initial conditions

abstract:
  General relativistic magnetohydrodynamic (GRMHD) simulations are providing
influential models for black hole spin measurements, gamma ray bursts, and
supermassive black hole feedback. Many of these simulations use the same
initial condition: a rotating torus of fluid in hydrostatic equilibrium. A
persistent concern is that simulation results sometimes depend on arbitrary
features of the initial torus. For example, the Bernoulli parameter (which is
related to outflows), appears to be controlled by the Bernoulli parameter of
the initial torus. In this paper, we give a new equilibrium torus solution and
describe two applications for the future. First, it can be used as a more
physical initial condition for GRMHD simulations than earlier torus solutions.
Second, it can be used in conjunction with earlier torus solutions to isolate
the simulation results that depend on initial conditions. We assume
axisymmetry, an ideal gas equation of state, constant entropy, and ignore
self-gravity. We fix an angular momentum distribution and solve the
relativistic Euler equations in the Kerr metric. The Bernoulli parameter,
rotation rate, and geometrical thickness of the torus can be adjusted
independently. Our torus tends to be more bound and have a larger radial extent
than earlier torus solutions. While this paper was in preparation, several
GRMHD simulations appeared based on our equilibrium torus. We believe it will
continue to provide a more realistic starting point for future simulations.


title: Colossal Magnetoresistance Manganites and Related Prototype Devices

abstract:
  We review colossal magnetoresistance in single phase manganites, as related
to the field sensitive spin charge interactions and phase separation; the
rectifying property and negative/positive magnetoresistance in
manganite/Nb:SrTiO3 pn junctions in relation to the special interface
electronic structure; magnetoelectric coupling in manganite/ferroelectric
structures that takes advantage of strain, carrier density, and magnetic field
sensitivity; tunneling magnetoresistance in tunnel junctions with dielectric,
ferroelectric, and organic semiconductor spacers using the fully spin polarized
nature of manganites; and the effect of particle size on magnetic properties in
manganite nanoparticles


title: Abelian symmetries of the N-Higgs-doublet model with Yukawa interactions

abstract:
  We investigate finite abelian groups which can represent symmetries of the
N-Higgs-doublet models with quarks. We build a general formalism based on the
powerful method of the Smith normal form and obtain an analytic upper bound on
the order of abelian symmetry groups for any N. We investigate in detail the
case N=2 and rederive known results in a more compact and intuitive fashion. We
also study the NHDM with the maximal finite abelian symmetry for all small N
cases up to N=5, and show that in each case all Yukawa textures compatible with
such symmetry originate from a unique basic structure. This work opens the way
to a systematic exploration of phenomenology of the NHDM with a desired
symmetry, and illustrates the power of the Smith normal form technique.


title: Inelastic neutron scattering studies of YFeO$_3$

abstract:
  Spin waves in the the rare earth orthorferrite YFeO$_3$ have been studied by
inelastic neutron scattering and analyzed with a full four-sublattice model
including contributions from both the weak ferromagnetic and hidden
antiferromagnetic orders. Antiferromagnetic (AFM) exchange interactions of $J_1
= -4.23 \pm 0.08$ (nearest-neighbors only) or $J_1 = -4.77 \pm 0.08$ meV and
$J_2 = -0.21 \pm 0.04$ meV lead to excellent fits for most branches at both low
and high energies. An additional branch associated with the hidden
antiferromagnetic order was observed. This work paves the way for studies of
other materials in this class containing spin reorientation transitions and
magnetic rare earth ions.


title:
Electronic properties of site-controlled (111)-oriented zinc-blende
  InGaAs/GaAs quantum dots calculated using a symmetry adapted
  $\mathbf{k}\cdot\mathbf{p}$ Hamiltonian

abstract:
  In this work, we present and evaluate a (111)-rotated eight-band
$\mathbf{k}\cdot\mathbf{p}$ Hamiltonian for the zinc-blende crystal lattice to
investigate the electronic properties of site-controlled InGaAs/GaAs quantum
dots grown along the [111] direction. We derive the rotated Hamiltonian
including strain and piezoelectric potentials. In combination with our
previously formulated (111)-oriented continuum elasticity model, we employ this
approach to investigate the electronic properties of a realistic
site-controlled (111)-grown InGaAs quantum dot. We combine these studies with
an evaluation of single-band effective mass and eight-band
$\mathbf{k}\cdot\mathbf{p}$ models, to investigate the capabilities of these
models for the description of electronic properties of (111)-grown zinc-blende
quantum dots. Moreover, the influence of second-order piezoelectric
contributions on the polarisation potential in such systems is studied. The
description of the electronic structure of nanostructures grown on
(111)-oriented surfaces can now be achieved with significantly reduced
computational costs in comparison to calculations performed using the
conventional (001)-oriented models.


title:
On the Performance Potential of Speculative Execution based on Branch
  and Value Prediction

abstract:
  Fluid Stochastic Petri Nets are used to capture the dynamic behavior of an
ILP processor, and discrete-event simulation is applied to assess the
performance potential of predictions and speculative execution in boosting the
performance of ILP processors that fetch, issue, execute and commit a large
number of instructions per cycle.


title: When periodicities enforce aperiodicity

abstract:
  Aperiodic tilings are non-periodic tilings defined by local rules. They are
widely used to model quasicrystals, and a central question is to understand
which of the non-periodic tilings are actually aperiodic. Among tilings, those
by rhombi can be easily seen as approximations of surfaces in higher
dimensional spaces. In particular, those which approximate irrational planes
are non-periodic. But which ones are also aperiodic? This paper introduces the
notion of subperiod, which links algebraic properties of a plane with geometric
properties of the tilings that approximate it. A necessary and sufficient
condition is obtained for tilings that can be seen in the four dimensional
Euclidean space. This result is then applied to some examples in higher
codimensions, notably tilings with n-fold rotational symmetry.


title:
Dynamics of the polarization of a pinned domain wall in a magnetic
  nanowire

abstract:
  We consider the dynamics of polarization of a single domain wall in a
magnetic nanowire, which is strongly pinned by impurities. In this case the
equation of motion for the polarization parameter does not include any other
dynamical variables and is nonlinear due to magnetic anisotropy. We calculated
numerically the magnetization dynamics for different choices of parameters
under short current pulses inducing polarization switching. Our results show
that the switching is most effective for very rapid current pulses. Damping
also enhances the switching probability.


title: ICT and Competitiveness of the Macedonian Economy

abstract:
  The ongoing process of liberalization, as well as the intensive technological
breakthrough have a great impact either on the macroeconomic policy creators,
or the dissimilarity of conventional approach to found a strategy of a certain
company. Bearing in mind the very notation, core characteristics of the concept
of competitiveness are needed to be explored, but also the necessity to
establish a national competitiveness strategy. However, the main attention
should be paid on the technological changes that affect the economic growth,
but the life standard increase, as well. Nevertheless, developing and
transitional economies are being down-sided with respect to the technological
and innovative capability that measurably implies the necessity to redefine the
conception of competitiveness. Taking into account the above clarifications,
the paper will set a comparative analysis of the key factors that pressure the
competitiveness of Balkans region countries, mainly by the composition of the
Growth Competitiveness Index. In addition, the major accent will be put on the
composite Technology index and its impact on the mainstream of the respective
total index. Finally, the paper will examine the possible change of Growth
Competitiveness Index ranking of the Macedonian economy, principally by the
variation of the Technology index rank.


title: Simulating e-Commerce Client-Server Interaction for Capacity Planning

abstract:
  Contemporary ways of doing business are heavily dependent on the
e-Commerce/e-Business paradigm. The highest priority of an e-Commerce Web
site's management is to assure pertinent Quality-of-Service (QoS) levels of
their Web services continually, in order to keep the potential e-Customers
satisfied. Otherwise, it faces an immense possibility of losing both
e-Customers and revenues, along with a big possibility of gaining bad
reputation due to either poor performance or unavailability of the e-Commerce
Web site. In order to avoid numerous unpleasant consequences, by designing and
implementing e-Commerce Web sites that will always meet e-Customer's high
expectations, a relevant performance models have to be utilized to obtain
appropriate performance metrics. A continuous assessment of current
performances and especially predicting future needs are the subjects of
capacity planning methodologies. Within this paper, such a predictive model has
been described and evaluated by using discrete-event simulation of both the
client-side and server-side processes involved. In addition, the paper
discusses the performance metrics obtained as a function of the intensity and
quality of the workload parameters.


title: Element Distinctness, Frequency Moments, and Sliding Windows

abstract:
  We derive new time-space tradeoff lower bounds and algorithms for exactly
computing statistics of input data, including frequency moments, element
distinctness, and order statistics, that are simple to calculate for sorted
data. We develop a randomized algorithm for the element distinctness problem
whose time T and space S satisfy T in O (n^{3/2}/S^{1/2}), smaller than
previous lower bounds for comparison-based algorithms, showing that element
distinctness is strictly easier than sorting for randomized branching programs.
This algorithm is based on a new time and space efficient algorithm for finding
all collisions of a function f from a finite set to itself that are reachable
by iterating f from a given set of starting points. We further show that our
element distinctness algorithm can be extended at only a polylogarithmic factor
cost to solve the element distinctness problem over sliding windows, where the
task is to take an input of length 2n-1 and produce an output for each window
of length n, giving n outputs in total. In contrast, we show a time-space
tradeoff lower bound of T in Omega(n^2/S) for randomized branching programs to
compute the number of distinct elements over sliding windows. The same lower
bound holds for computing the low-order bit of F_0 and computing any frequency
moment F_k, k neq 1. This shows that those frequency moments and the decision
problem F_0 mod 2 are strictly harder than element distinctness. We complement
this lower bound with a T in O(n^2/S) comparison-based deterministic RAM
algorithm for exactly computing F_k over sliding windows, nearly matching both
our lower bound for the sliding-window version and the comparison-based lower
bounds for the single-window version. We further exhibit a quantum algorithm
for F_0 over sliding windows with T in O(n^{3/2}/S^{1/2}). Finally, we consider
the computations of order statistics over sliding windows.


title: Geometric classifications of homogeneous production functions

abstract:
  In this paper, we completely classify homogeneous production functions with
an arbitrary number of inputs whose production hypersurfaces are flat. As an
immediate consequence, we obtain a complete classification of homogeneous
production functions with two inputs whose production surfaces are developable.


title:
Sufficient Conditions on the Optimality of Myopic Sensing in
  Opportunistic Channel Access: A Unifying Framework

abstract:
  This paper considers a widely studied stochastic control problem arising from
opportunistic spectrum access (OSA) in a multi-channel system, with the goal of
providing a unifying analytical framework whereby a number of prior results may
be viewed as special cases. Specifically, we consider a single wireless
transceiver/user with access to $N$ channels, each modeled as an iid
discrete-time two-state Markov chain. In each time step the user is allowed to
sense $k\leq N$ channels, and subsequently use up to $m\leq k$ channels out of
those sensed to be available. Channel sensing is assumed to be perfect, and for
each channel use in each time step the user gets a unit reward. The user's
objective is to maximize its total discounted or average reward over a finite
or infinite horizon. This problem has previously been studied in various
special cases including $k=1$ and $m=k\leq N$, often cast as a restless bandit
problem, with optimality results derived for a myopic policy that seeks to
maximize the immediate one-step reward when the two-state Markov chain model is
positively correlated. In this paper we study the general problem with $1\leq
m\leq k\leq N$, and derive sufficient conditions under which the myopic policy
is optimal for the finite and infinite horizon reward criteria, respectively.
It is shown that these results reduce to those derived in prior studies under
the corresponding special cases, and thus may be viewed as a set of unifying
optimality conditions. Numerical examples are also presented to highlight how
and why an optimal policy may deviate from the otherwise-optimal myopic sensing
given additional exploration opportunities, i.e., when $m<k$.


title:
Electric-field induced domain-wall dynamics: depinning and chirality
  switching

abstract:
  We theoretically study the equilibrium and dynamic properties of nanoscale
magnetic tunnel junctions (MTJs) and magnetic wires, in which an electric field
controls the magnetic anisotropy through spin-orbit coupling. By performing
micromagnetic simulations, we construct a rich phase diagram and find that, in
particular, the equilibrium magnetic textures can be tuned between Neel and
Bloch domain walls in an elliptical MTJ. Furthermore, we develop a
phenomenological model of a quasi-one-dimensional domain wall confined by a
parabolic potential and show that, near the Neel-to-Bloch-wall transition, a
pulsed electric field induces precessional domain-wall motion which can be used
to reverse the chirality of a Neel wall and even depin it. This domain-wall
motion controlled by electric fields, in lieu of applied current, may provide a
model for ultra-low-power domain-wall memory and logic devices.


title: Isomorphism, nonisomorphism, and amenability of L^p UHF algebras

abstract:
  In a previous paper, we introduced L^p UHF algebras for p in [1, \infty). We
concentrated on the spatial L^p UHF algebras, which are classified up to
isometric isomorphism by p and the scaled ordered K_0-group. In this paper, we
concentrate on a larger class, the L^p UHF algebras of tensor product type
constructed using diagonal similarities. Such an algebra is still simple and
has the same K-theory as the corresponding spatial L^p UHF algebra. For each
choice of p and the K-theory, we provide uncountably many nonisomorphic such
algebras. We further characterize the spatial algebras among them. In
particular, if A is one of these algebras, then A is isomorphic (not
necessarily isometrically) to a spatial L^p UHF algebra if and only if A is
amenable as a Banach algebra, also if and only if A has approximately inner
tensor flip. These conditions are also equivalent to a natural numerical
condition defined in terms of the ingredients used to construct the algebra.


title: Pseudo-automorphisms with no invariant foliation

abstract:
  We construct an example of a birational transformation of a rational
threefold for which the first and second dynamical degrees coincide and are
$>1$, but which does not preserve any holomorphic (singular) foliation. In
particular, this provides a negative answer to a question of Guedj. On our way,
we develop several techniques to study foliations which are invariant under
birational transformations.


title: Matching colored points with rectangles

abstract:
  Let $S$ be a point set in the plane such that each of its elements is colored
either red or blue. A matching of $S$ with rectangles is any set of
pairwise-disjoint axis-aligned rectangles such that each rectangle contains
exactly two points of $S$. Such a matching is monochromatic if every rectangle
contains points of the same color, and is bichromatic if every rectangle
contains points of different colors. In this paper we study the following two
problems:
  1. Find a maximum monochromatic matching of $S$ with rectangles.
  2. Find a maximum bichromatic matching of $S$ with rectangles.
  For each problem we provide a polynomial-time approximation algorithm that
constructs a matching with at least $1/4$ of the number of rectangles of an
optimal matching. We show that the first problem is $\mathsf{NP}$-hard even if
either the matching rectangles are restricted to axis-aligned segments or $S$
is in general position, that is, no two points of $S$ share the same $x$ or $y$
coordinate. We further show that the second problem is also $\mathsf{NP}$-hard,
even if $S$ is in general position. These $\mathsf{NP}$-hardness results follow
by showing that deciding the existence of a perfect matching is
$\mathsf{NP}$-complete in each case. The approximation results are based on a
relation of our problem with the problem of finding a maximum independent set
in a family of axis-aligned rectangles. With this paper we extend previous ones
on matching one-colored points with rectangles and squares, and matching
two-colored points with segments. Furthermore, using our techniques, we prove
that it is $\mathsf{NP}$-complete to decide a perfect matching with rectangles
in the case where all points have the same color, solving an open problem of
Bereg, Mutsanas, and Wolff [CGTA (2009)].


title: Group Learning and Opinion Diffusion in a Broadcast Network

abstract:
  We analyze the following group learning problem in the context of opinion
diffusion: Consider a network with $M$ users, each facing $N$ options. In a
discrete time setting, at each time step, each user chooses $K$ out of the $N$
options, and receive randomly generated rewards, whose statistics depend on the
options chosen as well as the user itself, and are unknown to the users. Each
user aims to maximize their expected total rewards over a certain time horizon
through an online learning process, i.e., a sequence of exploration (sampling
the return of each option) and exploitation (selecting empirically good
options) steps.
  Within this context we consider two group learning scenarios, (1) users with
uniform preferences and (2) users with diverse preferences, and examine how a
user should construct its learning process to best extract information from
other's decisions and experiences so as to maximize its own reward. Performance
is measured in {\em weak regret}, the difference between the user's total
reward and the reward from a user-specific best single-action policy (i.e.,
always selecting the set of options generating the highest mean rewards for
this user). Within each scenario we also consider two cases: (i) when users
exchange full information, meaning they share the actual rewards they obtained
from their choices, and (ii) when users exchange limited information, e.g.,
only their choices but not rewards obtained from these choices.


title: Non-local fractional model of rate independent plasticity

abstract:
  In the paper the generalisation of classical rate independent plasticity
using fractional calculus is presented. This new formulation is non-local due
to properties of applied fractional differential operator during definition of
kinematics. In the description small fractional strains assumption is hold
together with additive decomposition of total fractional strains into elastic
and plastic parts. Classical local rate independent plasticity is recovered as
a special case.


title: Local Support Vector Machines:Formulation and Analysis

abstract:
  We provide a formulation for Local Support Vector Machines (LSVMs) that
generalizes previous formulations, and brings out the explicit connections to
local polynomial learning used in nonparametric estimation literature. We
investigate the simplest type of LSVMs called Local Linear Support Vector
Machines (LLSVMs). For the first time we establish conditions under which
LLSVMs make Bayes consistent predictions at each test point $x_0$. We also
establish rates at which the local risk of LLSVMs converges to the minimum
value of expected local risk at each point $x_0$. Using stability arguments we
establish generalization error bounds for LLSVMs.


title: A Note on Density Estimation for Binary Sequences

abstract:
  A histogram estimate of the Radon-Nikodym derivative of a probability measure
with respect to a dominating measure is developed for binary sequences in
$\{0,1\}^{\mathbb{N}}$. A necessary and sufficient condition for the
consistency of the estimate in the mean-square sense is given. It is noted that
the product topology on $\{0,1\}^{\mathbb{N}}$ and the corresponding dominating
product measure pose considerable restrictions on the rate of sampling required
for the requisite convergence.


title: New and simple algorithms for stable flow problems

abstract:
  Stable flows generalize the well-known concept of stable matchings to markets
in which transactions may involve several agents, forwarding flow from one to
another. An instance of the problem consists of a capacitated directed network,
in which vertices express their preferences over their incident edges. A
network flow is stable if there is no group of vertices that all could benefit
from rerouting the flow along a walk.
  Fleiner established that a stable flow always exists by reducing it to the
stable allocation problem. We present an augmenting-path algorithm for
computing a stable flow, the first algorithm that achieves polynomial running
time for this problem without using stable allocation as a black-box
subroutine. We further consider the problem of finding a stable flow such that
the flow value on every edge is within a given interval. For this problem, we
present an elegant graph transformation and based on this, we devise a simple
and fast algorithm, which also can be used to find a solution to the stable
marriage problem with forced and forbidden edges.
  Finally, we study the stable multicommodity flow model introduced by
Kir\'{a}ly and Pap. The original model is highly involved and allows for
commodity-dependent preference lists at the vertices and commodity-specific
edge capacities. We present several graph-based reductions that show
equivalence to a significantly simpler model. We further show that it is
NP-complete to decide whether an integral solution exists.


title: Contractive maps in Mustafa-Sims metric spaces

abstract:
  The fixed point result in Mustafa-Sims metrical structures obtained by
Karapinar and Agarwal [Fixed Point Th. Appl., 2013, 2013:154] is deductible
from a corresponding one stated in terms of anticipative contractions over the
associated (standard) metric space.


title: Black Holes In Young Stellar Clusters

abstract:
  We present theoretical models for stellar black hole (BH) properties in
young, massive star clusters. Using a Monte Carlo code for stellar dynamics, we
model realistic star clusters with $N\simeq 5\times10^5$ stars and significant
binary fractions (up to 50%) with self-consistent treatments of stellar
dynamics and stellar evolution. We compute the formation rates and
characteristic properties of single and binary BHs for various representative
ages, cluster parameters, and metallicities. Because of dynamical interactions
and supernova (SN) kicks, more single BHs end up retained in clusters compared
to BHs in binaries. We also find that the ejection of BHs from a cluster is a
strong function of initial density. In low-density clusters (where dynamical
effects are negligible), it is mainly SN kicks that eject BHs from the cluster,
whereas in high-density clusters (initial central density $\rho_c(0) \sim 10^5
\, M_\odot\, {\rm pc}^{-3} $ in our models) the BH ejection rate is enhanced
significantly by dynamics. Dynamical interactions of binary systems in dense
clusters also modify the orbital period and eccentricity distributions while
also increasing the probability of a BH having a more massive companion.


title: To Stay Or To Switch: Multiuser Dynamic Channel Access

abstract:
  In this paper we study opportunistic spectrum access (OSA) policies in a
multiuser multichannel random access cognitive radio network, where users
perform channel probing and switching in order to obtain better channel
condition or higher instantaneous transmission quality. However, unlikely many
prior works in this area, including those on channel probing and switching
policies for a single user to exploit spectral diversity, and on probing and
access policies for multiple users over a single channel to exploit temporal
and multiuser diversity, in this study we consider the collective switching of
multiple users over multiple channels. In addition, we consider finite
arrivals, i.e., users are not assumed to always have data to send and demand
for channel follow a certain arrival process. Under such a scenario, the users'
ability to opportunistically exploit temporal diversity (the temporal variation
in channel quality over a single channel) and spectral diversity (quality
variation across multiple channels at a given time) is greatly affected by the
level of congestion in the system. We investigate the optimal decision process
in this case, and evaluate the extent to which congestion affects potential
gains from opportunistic dynamic channel switching.


title: Hierarchical Subdivision of the Simple Cubic Lattice

abstract:
  The simple cubic lattice defines a set of points at regular distances. The
volume of the Voronoi cells around each point may serve as a weight for
integration over the entire space. We add interstitial points to this grid
according to the rule that these have maximum distance to the existing points,
or by the equivalent rule that they are placed at the vertices of the Voronoi
cells of the existing lattice. Choices of that kind appear in numerical
sampling with maximum independent data points if the numerical expense of
computing values represented at the lattice points is high. The volumes and
shapes of the Voronoi cells of these enriched/supersampled lattices are
discussed in detail while this insertion is recursively executed three times in
succession.


title: Plasmonic Scaling of Superconducting Metamaterials

abstract:
  Superconducting metamaterials are utilized to study the approach to the
plasmonic limit simply by tuning temperature to modify the superfluid density,
and thus the superfluid plasma frequency. We examine the persistence of
artificial magnetism in a metamaterial made with superconductors in the
plasmonic limit, and compare to the electromagnetic behavior of normal metals
as a function of frequency as the plasma frequency is approached from below.
Spiral-shaped Nb thin film meta-atoms of scaled dimensions are employed to
explore the plasmonic behavior in these superconducting metamaterials, and the
scaling condition allows extraction of the temperature dependent superfluid
density, which is found to be in good agreement with expectations.


title:
Relative entropy and contraction for extremal shocks of Conservation
  Laws up to a shift

abstract:
  We consider systems of conservation laws endowed with a convex entropy. We
show the contraction, up to a translation, to extremal entropic shocks, for a
pseudo-distance based on the notion of relative entropy. The contraction holds
for bounded entropic weak solutions having an additional trace property. The
pseudo-distance depends only on the fixed extremal entropic shocks in play. In
particular, it can be chosen uniformly for any entropic weak solutions which
are compared to a fixed shock. The boundedness of the solutions controls the
strength of the shift needed to get the contraction. However, no $BV$ estimate
is needed on the weak solutions considered. The theory holds without smallness
condition. For fluid mechanics, the theory handles solutions with vacuum.


title:
Existence results for systems with nonlinear coupled nonlocal initial
  conditions

abstract:
  The purpose of the present work is to study the existence of solutions to
initial value problems for nonlinear first order differential systems with
nonlinear nonlocal boundary conditions of functional type. The existence
results are established by means of the Perov, Schauder and Leray-Schauder
fixed point principles combined with a technique based on vector-valued metrics
and convergent to zero matrices.


title: Bose-Hubbard model with occupation-parity couplings

abstract:
  We study a Bose-Hubbard model having on-site repulsion, nearest-neighbor
tunneling, and ferromagneticlike coupling between occupation parities of
nearest-neighbor sites. For a uniform system in any dimension at zero
tunneling, we obtain an exact phase diagram characterized by Mott-insulator
(MI) and pair liquid phases and regions of phase separation of two MIs. For a
general trapped system in one and two dimensions with finite tunneling, we
perform quantum Monte Carlo and Gutzwiller mean-field calculations, both of
which show the evolution of the system, as the parity coupling increases, from
a superfluid to wedding-cake-structure MIs with their occupations jumping by 2.
We also identify an exotic pair superfluid at relatively large tunneling
strength. Our model ought to effectively describe recent findings in imbalanced
Fermi gases in two-dimensional optical lattices and also potentially apply to
an anisotropic version of bilinear-biquadratic spin systems.


title: Observational constraints on dark energy cosmological model parameters

abstract:
  The expansion rate of the Universe changes with time, initially slowing
(decelerating) when the universe was matter dominated, because of the mutual
gravitational attraction of all the matter in it, and more recently speeding up
(accelerating). A number of cosmological observations now strongly support the
idea that the Universe is spatially flat (provided the dark energy density is
at least approximately time independent) and is currently undergoing an
accelerated cosmological expansion. A majority of cosmologists consider "dark
energy" to be the cause of this observed accelerated cosmological expansion.
  The "standard" model of cosmology is the spatially-flat {\Lambda}CDM model.
Although most predictions of the {\Lambda}CDM model are reasonably consistent
with measurements, the {\Lambda}CDM model has some curious features. To
overcome these difficulties, different Dark Energy models have been proposed.
Two of these models, the XCDM parametrization and the slow rolling scalar field
model $\phi$CDM, along with "standard" {\Lambda}CDM, with the generalization of
XCDM and $\phi$CDM in non-flat spatial geometries are considered here and
observational data are used to constrain their parameter sets.
  In this thesis, we start with a overview of the general theory of relativity,
Friedmann's equations, and distance measures in cosmology. In the following
chapters we explain how we can constrain the three above mentioned cosmological
models using three data sets: measurements of the Hubble parameter $H(z)$,
Supernova apparent magnitudes, and the BAO peak length scale, as functions of
redshift $z$. We then discuss constraints on the deceleration-acceleration
transition redshift $z_{\rm da}$ using unbinned and binned $H(z)$ data.
  Finally, we incorporate the spatial curvature in the XCDM and $\phi$CDM model
and determine observational constraints on the parameters of these expanded
models.


title:
Hopping Transport through Defect-induced Localized States in Molybdenum
  Disulfide

abstract:
  Molybdenum disulfide is a novel two-dimensional semiconductor with potential
applications in electronic and optoelectronic devices. However, the nature of
charge transport in back-gated devices still remains elusive as they show much
lower mobility than theoretical calculations and native n-type doping. Here we
report transport study in few-layer molybdenum disulfide, together with
transmission electron microscopy and density functional theory. We provide
direct evidence that sulfur vacancies exist in molybdenum disulfide,
introducing localized donor states inside the bandgap. Under low carrier
densities, the transport exhibits nearest-neighbor hopping at high temperatures
and variable-range hopping at low temperatures, which can be well explained
under Mott formalism. We suggest that the low-carrier-density transport is
dominated by hopping via these localized gap states. Our study reveals the
important role of short-range surface defects in tailoring the properties and
device applications of molybdenum disulfide.


title: Silicon nanostructures toxicity. An ab inito approach

abstract:
  Silicon nanoparticles are widely used in the medical area and until now they
have not manifested toxicological effects in humans beings. In order to
understand the physical properties that determine their low-toxicity, we
perform ab initio computational simulations of silicon nanoclusters, pure,
p-doped and hollow structured. The topological and electronic properties
obtained pointed out to the number of dangling bonds and electronic density as
fundamental parameters to locate active sites and directly related to toxicity,
besides the size and surface chemistry of the silicon nanoparticle.


title:
Why Do the Relativistic Masses and Momenta of Faster-than-Light
  Particles Decrease as their Speeds Increase?

abstract:
  It has recently been shown within a formal axiomatic framework using a
definition of four-momentum based on the St\"uckelberg-Feynman-Sudarshan-Recami
"switching principle" that Einstein's relativistic dynamics is logically
consistent with the existence of interacting faster-than-light inertial
particles. Our results here show, using only basic natural assumptions on
dynamics, that this definition is the only possible way to get a consistent
theory of such particles moving within the geometry of Minkowskian spacetime.
We present a strictly formal proof from a streamlined axiom system that given
any slow or fast inertial particle, all inertial observers agree on the value
of $\mathsf{m}\cdot \sqrt{|1-v^2|}$, where $\mathsf{m}$ is the particle's
relativistic mass and $v$ its speed. This confirms formally the widely held
belief that the relativistic mass and momentum of a positive-mass
faster-than-light particle must decrease as its speed increases.


title: Freezing and phase separation of self-propelled disks

abstract:
  We study numerically a model of non-aligning self-propelled particles
interacting through steric repulsion, which was recently shown to exhibit
active phase separation in two dimensions in the absence of any attractive
interaction or breaking of the orientational symmetry. We construct a phase
diagram in terms of activity and packing fraction and identify three distinct
regimes: a homogeneous liquid with anomalous cluster size distribution, a
phase-separated state both at high and at low density, and a frozen phase. We
provide a physical interpretation of the various regimes and develop scaling
arguments for the boundaries separating them.


title: Black box groups isomorphic to ${\rm PGL}(2,2^e)$

abstract:
  A deterministic polynomial-time algorithm constructs an isomorphism between
${\rm PGL}(2,2^e)$ and a black box group to which it is isomorphic.


title: Revisiting Optimal Power Control: its Dual Effect on SNR and Contention

abstract:
  In this paper we study a transmission power tune problem with densely
deployed 802.11 Wireless Local Area Networks (WLANs). While previous papers
emphasize on tuning transmission power with either PHY or MAC layer separately,
optimally setting each Access Point's (AP's) transmission power of a densely
deployed 802.11 network considering its dual effects on both layers remains an
open problem. In this work, we design a measure by evaluating impacts of
transmission power on network performance on both PHY and MAC layers. We show
that such an optimization problem is intractable and then we investigate and
develop an analytical framework to allow simple yet efficient solutions.
Through simulations and numerical results, we observe clear benefits of the
dual-effect model compared to solutions optimizing solely on a single layer;
therefore, we conclude that tuning transmission power from a dual layer
(PHY-MAC) point of view is essential and necessary for dense WLANs. We further
form a game theoretical framework and investigate above power-tune problem in a
strategic network. We show that with decentralized and strategic users, the
Nash Equilibrium (N.E.) of the corresponding game is in-efficient and
thereafter we propose a punishment based mechanism to enforce users to adopt
the social optimal strategy profile under both perfect and imperfect sensing
environments.


title: On the modularity of reducible mod l Galois representations

abstract:
  We prove that every odd semisimple reducible (2-dimensional) mod l Galois
representation arises from a cuspidal eigenform. In addition, we investigate
the possible different types (level, weight, character) of such a modular form.
When the representation is the direct sum of the trivial character and a power
of the mod l cyclotomic character, we are able to characterize the primes that
can arise as levels of the associated newforms. As an application, we determine
a new explicit lower bound for the highest degree among the fields of
coefficients of newforms of trivial Nebentypus and prime level. The bound is
valid in a subset of the primes with natural (lower) density at least one half.


title:
Coronal Mass Ejections Observed at the Total Solar Eclipse on 13
  November 2012

abstract:
  We carried out white-light observations of the total solar eclipse on 13
November 2012 at two sites, where the totality occurred 35 minutes apart. We
caught an ongoing coronal mass ejection (CME) and a pre-CME loop structure just
before the eruption in the height range between 1-2 R_sun. The source region of
CMEs was revealed to be in this height range, where the material and the
magnetic field of CMEs were located before the eruption. This height range
includes the gap between the extreme ultraviolet observations of the low corona
and the spaceborne white-light observations of the high corona, but the eclipse
observation shows that this height range is essentially important to study the
CME initiation. The eclipse observation is basically just a snapshot of CMEs,
but it indicates that future continuous observations of CMEs within this height
range are promising.


title:
A New Method for the Analysis of Signals: The Square Wave Transform
  (SWT)

abstract:
  The results obtained by analyzing signals with the Square Wave Method (SWM)
introduced previously can be presented in the frequency domain clearly and
precisely by using the Square Wave Transform (SWT) described here. As an
example, the SWT is used to analyze a sequence of samples (that is, of measured
values) taken from an electroencephalographic recording.


title: The Incidence and Cross Methods for Efficient Radar Detection

abstract:
  The designation of the radar system is to detect the position and velocity of
targets around us. The radar transmits a waveform, which is reflected back from
the targets, and echo waveform is received. In a commonly used model, the echo
is a sum of a superposition of several delay-Doppler shifts of the transmitted
waveform, and a noise component. The delay and Doppler parameters encode,
respectively, the distances, and relative velocities, between the targets and
the radar. Using standard digital-to-analog and sampling techniques, the
estimation task of the delay-Doppler parameters, which involves waveforms, is
reduced to a problem for complex sequences of finite length N. In these notes
we introduce the Incidence and Cross methods for radar detection. One of their
advantages, is robustness to inhomogeneous radar scene, i.e., for sensing small
targets in the vicinity of large objects. The arithmetic complexity of the
incidence and cross methods is O(NlogN + r^3) and O(NlogN + r^2), for r
targets, respectively. In the case of noisy environment, these are the fastest
radar detection techniques. Both methods employ chirp sequences, which are
commonly used by radar systems, and hence are attractive for real world
applications.


title:
Asymptotic analysis for Merton's problem with transaction costs in power
  utility case

abstract:
  We revisit the optimal investment and consumption problem with proportional
transaction costs. We prove that both the value function and the slopes of the
lines demarcating the no-trading region are analytic functions of cube root of
the transaction cost parameter. Also, we can explicitly calculate the
coefficients of the fractional power series expansions of the value function
and the no-trading region.


title:
A Further Study of Superoutbursts and Superhumps in SU UMa Stars by the
  Kepler Light Curves of V1504 Cygni and V344 Lyrae

abstract:
  We made a supplemental study of the superoutbursts and superhumps in SU UMa
stars by using the recently released Kepler public data of V1504 Cyg and V344
Lyr. One of the superoutbursts in V1504 Cyg was preceded by a precursor normal
outburst which was well separated from the main superoutburst. The superhump
first appeared during the descending branch of the precursor normal outburst
and it continued into quiescence (the deep dip between the precursor and the
main superoutburst), and it began to grow in amplitude with the growth of the
main superoutburst after quiescence ended. A similar phenomenon was also
observed in V344 Lyr. This observation demonstrates very clearly that the
superoutburst was triggered by the superhump (i.e., by the tidal instability),
supporting the thermal-tidal instability model. Smak (2013, Acta Astron., 63,
109, arXiv:1301.0187) criticized our previous paper (Osaki and Kato, 2013,
PASJ, 65, 50, arXiv:1212.1516) and challenged our main conclusion that various
observational lines of evidence of V1504 Cyg support the thermal-tidal
instability model for the superoutbursts of SU UMa stars. We present our
detailed accounts to all of his criticisms by offering clear explanations. We
conclude that the thermal-tidal instability model is after all only the viable
model for the superoutbursts and superhumps in SU UMa stars.


title: Symplectic Integration of Magnetic Systems

abstract:
  Dependable numerical results from long-time simulations require stable
numerical integration schemes. For Hamiltonian systems, this is achieved with
symplectic integrators, which conserve the symplectic condition and exactly
solve for the dynamics for an approximate Hamiltonian. The conventional
generating function formalism used for Hamiltonian systems is problematic for
magnetic systems, as the Hamiltonian is not easily separable. This paper
presents a derivation of symplectic integrators from a discretized action.
Using this method, it is shown that the integrator due to Boris is a symplectic
integrator in the non-relativistic limit, and a relativistic integrator is
derived.


title:
A shotgun sampling solution for the common input problem in neural
  connectivity inference

abstract:
  Inferring connectivity in neuronal networks remains a key challenge in
statistical neuroscience. The `common input' problem presents the major
roadblock: it is difficult to reliably distinguish causal connections between
pairs of observed neurons from correlations induced by common input from
unobserved neurons. Since available recording techniques allow us to sample
from only a small fraction of large networks simultaneously with sufficient
temporal resolution, naive connectivity estimators that neglect these common
input effects are highly biased. This work proposes a `shotgun' experimental
design, in which we observe multiple sub-networks briefly, in a serial manner.
Thus, while the full network cannot be observed simultaneously at any given
time, we may be able to observe most of it during the entire experiment. Using
a generalized linear model for a spiking recurrent neural network, we develop
scalable approximate Bayesian methods to perform network inference given this
type of data, in which only a small fraction of the network is observed in each
time bin. We demonstrate in simulation that, using this method: (1) The shotgun
experimental design can eliminate the biases induced by common input effects.
(2) Networks with thousands of neurons, in which only a small fraction of the
neurons is observed in each time bin, could be quickly and accurately
estimated. (3) Performance can be improved if we exploit prior information
about the probability of having a connection between two neurons, its
dependence on neuronal cell types (e.g., Dale's law), or its dependence on the
distance between neurons.


title:
Coherent configurations over copies of association schemes of prime
  order

abstract:
  Let $G$ be a group acting faithfully and transitively on $\Omega_i$ for
$i=1,2$. A famous theorem by Burnside implies the following fact: If
$|\Omega_1|=|\Omega_2|$ is a prime and the rank of one of the actions is
greater than two, then the actions are equivalent, or equivalently
$|(\alpha,\beta)^G|=|\Omega_1|=|\Omega_2|$ for some $(\alpha,\beta)\in
\Omega_1\times \Omega_2$.
  In this paper we consider a combinatorial analogue to this fact through the
theory of coherent configurations, and give some arithmetic sufficient
conditions for a coherent configuration with two homogeneous components of
prime order to be uniquely determined by one of the homogeneous components.


title:
A free boundary problem modeling electrostatic MEMS: II. nonlinear
  bending effects

abstract:
  Well-posedness of a free boundary problem for electrostatic
microelectromechanical systems (MEMS) is investigated when nonlinear bending
effects are taken into account. The model describes the evolution of the
deflection of an electrically conductive elastic membrane suspended above a
fixed ground plate together with the electrostatic potential in the free domain
between the membrane and the fixed ground plate. The electrostatic potential is
harmonic in that domain and its values are held fixed along the membrane and
the ground plate. The equation for the membrane deflection is a parabolic
quasilinear fourth-order equation, which is coupled to the gradient trace of
the electrostatic potential on the membrane.


title:
J-class of finitely generated abelian semigroups of affine mpas on C^n
  and Hypercyclicity

abstract:
  We give a characterization of hypercyclic using (locally hypercyclic) of
semigroup G of affine maps of C^n. We prove the existence of a G-invariant open
subset of C^n in which any locally hypercyclic orbit is dense in C^n.


title:
Gaussian fluctuations for linear spectral statistics of large random
  covariance matrices

abstract:
  Consider a $N\times n$ matrix $\Sigma_n=\frac{1}{\sqrt{n}}R_n^{1/2}X_n$,
where $R_n$ is a nonnegative definite Hermitian matrix and $X_n$ is a random
matrix with i.i.d. real or complex standardized entries. The fluctuations of
the linear statistics of the eigenvalues \[\operatorname {Trace}f
\bigl(\Sigma_n\Sigma_n^*\bigr)=\sum_{i=1}^Nf(\lambda_i),\qquad (\lambda_i)\
eigenvalues\ of\ \Sigma_n\Sigma_n^*,\] are shown to be Gaussian, in the regime
where both dimensions of matrix $\Sigma_n$ go to infinity at the same pace and
in the case where $f$ is of class $C^3$, that is, has three continuous
derivatives. The main improvements with respect to Bai and Silverstein's CLT
[Ann. Probab. 32 (2004) 553-605] are twofold: First, we consider general
entries with finite fourth moment, but whose fourth cumulant is nonnull, that
is, whose fourth moment may differ from the moment of a (real or complex)
Gaussian random variable. As a consequence, extra terms proportional to $ \vert
\mathcal{V}\vert ^2=\bigl|\mathbb{E}\bigl(X_{11}^n\bigr) ^2\bigr|^2$ and
$\kappa=\mathbb{E}\bigl \vert X_{11}^n\bigr \vert ^4-\vert {\mathcal{V}}\vert
^2-2$ appear in the limiting variance and in the limiting bias, which not only
depend on the spectrum of matrix $R_n$ but also on its eigenvectors. Second, we
relax the analyticity assumption over $f$ by representing the linear statistics
with the help of Helffer-Sj\"{o}strand's formula. The CLT is expressed in terms
of vanishing L\'{e}vy-Prohorov distance between the linear statistics'
distribution and a Gaussian probability distribution, the mean and the variance
of which depend upon $N$ and $n$ and may not converge.


title:
Clustering large number of extragalactic spectra of galaxies and quasars
  through canopies

abstract:
  Cluster analysis is the distribution of objects into different groups or more
precisely the partitioning of a data set into subsets (clusters) so that the
data in subsets share some common trait according to some distance measure.
Unlike classi cation, in clustering one has to rst decide the optimum number of
clusters and then assign the objects into different clusters. Solution of such
problems for a large number of high dimensional data points is quite
complicated and most of the existing algorithms will not perform properly. In
the present work a new clustering technique applicable to large data set has
been used to cluster the spectra of 702248 galaxies and quasars having 1540
points in wavelength range imposed by the instrument. The proposed technique
has successfully discovered ve clusters from this 702248X1540 data matrix.


title:
Automatically Extracting Instances of Code Change Patterns with AST
  Analysis

abstract:
  A code change pattern represents a kind of recurrent modification in
software. For instance, a known code change pattern consists of the change of
the conditional expression of an if statement. Previous work has identified
different change patterns. Complementary to the identification and definition
of change patterns, the automatic extraction of pattern instances is essential
to measure their empirical importance. For example, it enables one to count and
compare the number of conditional expression changes in the history of
different projects. In this paper we present a novel approach for search
patterns instances from software history. Our technique is based on the
analysis of Abstract Syntax Trees (AST) files within a given commit. We
validate our approach by counting instances of 18 change patterns in 6
open-source Java projects.


title:
A non linear approximation method for solving high dimensional partial
  differential equations: Application in Finance

abstract:
  We study an algorithm which has been proposed by Chinesta et al. to solve
high-dimensional partial differential equations. The idea is to represent the
solution as a sum of tensor products and to compute iteratively the terms of
this sum. This algorithm is related to the so-called greedy algorithm
introduced by Temlyakov. In this paper, we investigate the application of the
greedy algorithm in finance and more precisely to the option pricing problem.
We approximate the solution to the Black-Scholes equation and we propose a
variance reduction method. In numerical experiments, we obtain results for up
to 10 underlyings. Besides, the proposed variance reduction method permits an
important reduction of the variance in comparison with a classical Monte Carlo
method.