title:
Understanding the origins of the intrinsic dead-layer effect in
  nanocapacitors

abstract:
  Thin films of high-permittivity dielectrics are considered ideal candidates
for realizing high charge density nanosized capacitors for use in next
generation energy storage and nanoelectronic applications. The experimentally
observed capacitance of such film nanocapacitors is, however, an order of
magnitude lower than expected. This dramatic drop in capacitance is attributed
to the so called dead layer - a low-permittivity layer at the metal-dielectric
interface in series with the high-permittivity dielectric. The exact nature of
the dead layer and the reasons for its origin still remain somewhat unclear.
Based on insights gained from recently published ab initio work on
SrRuO3/SrTiO3/SrRuO3 and our first principle simulations on Au/MgO/Au and
Pt/MgO/Pt nanocapacitors, we construct an analytical model that isolates the
contributions of various physical mechanisms to the intrinsic dead layer. In
particular we argue that strain-gradients automatically arise in very thin
films even in absence of external strain inducers and, due to flexoelectric
coupling, are dominant contributors to the dead layer effect. Our theoretical
results compare well with existing as well as our own ab initio calculations
and suggest that inclusion of flexoelectricity is necessary for qualitative
reconciliation of atomistic results. Our results also hint at some novel
remedies for mitigating the dead layer effect.


title: Energy-supercritical NLS: critical $\dot H^s$-bounds imply scattering

abstract:
  We consider two classes of defocusing energy-supercritical nonlinear
Schr\"odinger equations in dimensions $d\geq 5$. We prove that if the solution
$u$ is apriorily bounded in the critical Sobolev space, that is, $u\in
L_t^\infty \dot H^{s_c}_x$, then $u$ is global and scatters.


title:
Index theorem for topological excitations on R^3 * S^1 and Chern-Simons
  theory

abstract:
  We derive an index theorem for the Dirac operator in the background of
various topological excitations on an R^3 \times S^1 geometry. The index
theorem provides more refined data than the APS index for an instanton on R^4
and reproduces it in decompactification limit. In the R^3 limit, it reduces to
the Callias index theorem. The index is expressed in terms of topological
charge and the eta-invariant associated with the boundary Dirac operator.
Neither topological charge nor eta-invariant is typically an integer, however,
the non-integer parts cancel to give an integer-valued index. Our derivation is
based on axial current non-conservation--an exact operator identity valid on
any four-manifold--and on the existence of a center symmetric, or approximately
center symmetric, boundary holonomy (Wilson line). We expect the index theorem
to usefully apply to many physical systems of interest, such as low temperature
(large S^1, confined) phases of gauge theories, center stabilized Yang-Mills
theories with vector-like or chiral matter (at S^1 of any size), and
supersymmetric gauge theories with supersymmetry-preserving boundary conditions
(also at any S^1). In QCD-like and chiral gauge theories, the index theorem
should shed light into the nature of topological excitations responsible for
chiral symmetry breaking and the generation of mass gap in the gauge sector. We
also show that imposing chirally-twisted boundary condition in gauge theories
with fermions induces a Chern-Simons term in the infrared. This suggests that
some QCD-like gauge theories should possess components with a topological
Chern-Simons phase in the small S^1 regime.


title: 50 Years of Computer Simulation -- a Personal View

abstract:
  In the half century since the 1950s computer simulation has transformed our
understanding of physics. The rare, expensive, slow, and bulky mainframes of
World War II have given way to today's millions of cheap, fast, desksized
workstations and personal computers. As a result of these changes, the
theoretical formal view of physics has gradually shifted, so as to focus on the
pragmatic and useful. General but vague approaches are being superceded by
specific results for definite models. During this evolving change of emphasis I
learned, developed, and described my simulation skills at Michigan, at Duke, at
Livermore, and in Nevada, while forming increasingly wide-ranging contacts
around the world. Computation is now pervasive in all the scientific fields. My
own focus has been on the physics of particle simulations, mainly away from
equilibrium. I outline my particle work here. It has led me to a model-based
understanding of both equilibrium and nonequilibrium physics. There are still
some gaps. There is still much to do.


title:
A dynamic scheme for generating number squeezing in Bose-Einstein
  condensates through nonlinear interactions

abstract:
  We develop a scheme to generate number squeezing in a Bose-Einstein
condensate by utilizing interference between two hyperfine levels and nonlinear
atomic interactions. We describe the scheme using a multimode quantum field
model and find agreement with a simple analytic model in certain regimes. We
demonstrate that the scheme gives strong squeezing for realistic choices of
parameters and atomic species. The number squeezing can result in noise well
below the quantum limit, even if the initial noise on the system is classical
and much greater than that of a poisson distribution.

categories: quant-ph cond-mat.other cond-mat.quant-gas physics.atom-ph


title: Interactions of Galaxies in the Galaxy Cluster Environment

abstract:
  We study the dependence of galaxy properties on the clustercentric radius and
the environment attributed to the nearest neighbor galaxy using the SDSS
galaxies associated with the Abell galaxy clusters. We find that there exists a
characteristic scale where the properties of galaxies suddenly start to depend
on the clustercentric radius at fixed neighbor environment. The characteristic
scale is $1\sim 3$ times the cluster virial radius depending on galaxy
luminosity. Existence of the characteristic scale means that the local galaxy
number density is not directly responsible for the morphology-density relation
in clusters because the local density varies smoothly with the clustercentric
radius and has no discontinuity in general. What is really working in clusters
is the morphology-clustercentric radius-neighbor environment relation, where
the neighbor environment means both neighbor morphology and the local mass
density attributed to the neighbor. The morphology-density relation appears
working only because of the statistical correlation between the nearest
neighbor distance and the local galaxy number density. We find strong evidence
that the hydrodynamic interactions with nearby early-type galaxies is the main
drive to quenching star formation activity of late-type galaxies in clusters.
The hot cluster gas seems to play at most a minor role down to one tenth of the
cluster virial radius. We also find that the viable mechanisms which can
account for the clustercentric radius dependence of the structural and internal
kinematics parameters are harassment and interaction of galaxies with the
cluster potential. The morphology transformation of the late-type galaxies in
clusters seems to have taken place through both galaxy-galaxy hydrodynamic
interactions and galaxy-cluster/galaxy-galaxy gravitational interactions.


title:
Realistic Type IIB Supersymmetric Minkowski Flux Models without the
  Freed-Witten Anomaly

abstract:
  We show that there exist supersymmetric Minkowski vacua on Type IIB toroidal
orientifold with general flux compactifications where the RR tadpole
cancellation conditions can be relaxed and the Freed-Witten anomaly can be
cancelled elegantly. We present a realistic Pati-Salam like flux model without
the Freed-Witten anomaly. At the string scale, we can break the gauge symmetry
down to the Standard Model (SM) gauge symmetry, achieve the gauge coupling
unification naturally, and decouple all the extra chiral exotic particles.
Thus, we have the supersymmetric SMs with/without SM singlet(s) below the
string scale. Also, we can explain the SM fermion masses and mixings. In
addition, the unified gauge coupling and the real parts of the dilaton and
K\"ahler moduli are functions of the four-dimensional dilaton. The complex
structure moduli and one linear combination of the imaginary parts of the
K\"ahler moduli can be determined as functions of the fluxes and the dilaton.


title: Family Gauge Symmetry and Koide's Mass Formula

abstract:
  Koide's mass formula is an empirical relation among the charged lepton masses
which holds with a striking precision. We propose a mechanism for cancelling
the QED correction to Koide's formula. This is discussed in an effective theory
with U(3) family gauge symmetry and a scenario in which this symmetry is
unified with SU(2)_L symmetry at 10^2-10^3 TeV scale.


title:
Evidence for Coexistence of Superconductivity and Magnetism in Single
  Crystals of Co-doped SrFe$_2$As$_2$

abstract:
  In order to investigate whether magnetism and superconductivity coexist in
Co-doped SrFe$_2$As$_2$, we have prepared single crystals of
SrFe$_{2-x}$Co$_x$As$_2$, $x$ = 0 and 0.4, and characterized them via X-ray
diffraction, electrical resistivity in zero and applied field up to 9 T as well
as at ambient and applied pressure up to 1.6 GPa, and magnetic susceptibility.
At $x$ = 0.4, there is both magnetic and resistive evidence for a spin density
wave transition at 120 K, while $T_c$ = 19.5 K - indicating coexistent
magnetism and superconductivity. A discussion of how these results compare with
reported results, both in SrFe$_{2-x}$Co$_x$As$_2$ and in other doped 122
compounds, is given.


title: A limit approach to group homology

abstract:
  In this paper, we consider for any free presentation $G = F/R$ of a group $G$
the coinvariance $H_{0}(G,R_{ab}^{\otimes n})$ of the $n$-th tensor power of
the relation module $R_{ab}$ and show that the homology group
$H_{2n}(G,{\mathbb Z})$ may be identified with the limit of the groups
$H_{0}(G,R_{ab}^{\otimes n})$, where the limit is taken over the category of
these presentations of $G$. We also consider the free Lie ring generated by the
relation module $R_{ab}$, in order to relate the limit of the groups
$\gamma_{n}R/[\gamma_{n}R,F]$ to the $n$-torsion subgroup of $H_{2n}(G,{\mathbb
Z})$.


title: $L^2$-Betti numbers and non-unitarizable groups without free subgroups

abstract:
  We show that there exist non-unitarizable groups without non-abelian free
subgroups. Both torsion and torsion free examples are constructed. As a
by-product, we show that there exist finitely generated torsion groups with
non-vanishing first $L^2$-Betti numbers. We also relate the well-known problem
of whether every hyperbolic group is residually finite to an open question
about approximation of $L^2$-Betti numbers.


title:
Interoperability between Heterogeneous Federation Architectures:
  Illustration with SAML and WS-Federation

abstract:
  Digital identity management intra and inter information systems, and, service
oriented architectures, are the roots of identity federation. This kind of
security architectures aims at enabling information system interoperability.
Existing architectures, however, do not consider interoperability of
heterogeneous federation architectures, which rely on different federation
protocols.In this paper, we try to initiate an in-depth reflection on this
issue, through the comparison of two main federation architecture
specifications: SAML and WS-Federation. We firstly propose an overall outline
of identity federation. We furthermore address the issue of interoperability
for federation architectures using a different federation protocol. Afterwards,
we compare SAML and WS-Federation. Eventually, we define the ways of
convergence, and therefore, of interoperability.


title: Performance of the First ANTARES Detector Line

abstract:
  In this paper we report on the data recorded with the first Antares detector
line. The line was deployed on the 14th of February 2006 and was connected to
the readout two weeks later. Environmental data for one and a half years of
running are shown. Measurements of atmospheric muons from data taken from
selected runs during the first six months of operation are presented.
Performance figures in terms of time residuals and angular resolution are
given. Finally the angular distribution of atmospheric muons is presented and
from this the depth profile of the muon intensity is derived.


title:
Geometrical description of smooth projective symmetric varieties with
  Picard number one

abstract:
  In a previous paper we have classified the smooth projective symmetric
G-varieties with Picard number one (and G semisimple). In this work we give a
geometrical description of such varieties. In particular, we determine their
group of automorphisms. When this group, Aut(X), acts non-transitively on X, we
describe a G-equivariant embedding of the variety X in a homogeneous variety
(with respect to a larger group).


title:
A unified approach to Mimetic Finite Difference, Hybrid Finite Volume
  and Mixed Finite Volume methods

abstract:
  We investigate the connections between several recent methods for the
discretization of anisotropic heterogeneous diffusion operators on general
grids. We prove that the Mimetic Finite Difference scheme, the Hybrid Finite
Volume scheme and the Mixed Finite Volume scheme are in fact identical up to
some slight generalizations. As a consequence, some of the mathematical results
obtained for each of the method (such as convergence properties or error
estimates) may be extended to the unified common framework. We then focus on
the relationships between this unified method and nonconforming Finite Element
schemes or Mixed Finite Element schemes, obtaining as a by-product an explicit
lifting operator close to the ones used in some theoretical studies of the
Mimetic Finite Difference scheme. We also show that for isotropic operators, on
particular meshes such as triangular meshes with acute angles, the unified
method boils down to the well-known efficient two-point flux Finite Volume
scheme.


title: What drives the insulating state in ultrathin films of SrRuO3?

abstract:
  Using density functional calculations we have examined the evolution of the
electronic structure of SrRuO3 films grown on SrTiO3 substrates as a function
of film thickness. At the ultrathin limit of two monolayers (RuO2-terminated
surface) the films are found to be at the brink of a spin-state transition
which drives the system to an antiferromagnetic and insulating state.
Increasing the film thickness to four monolayers, one finds the surprising
result that two entirely different solutions coexist. An antiferromagnetic
insulating solution coexists with a metallic solution corresponding to an
antiferromagnetic surface and a ferromagnetic bulk. The electronic structure
found at the ultrathin limit persists for thicker films and an unusual result
is predicted. Thicker films are found to be metallic as expected for the bulk,
but the magnetism does not directly evolve to the bulk ferromagnetic state. The
surface remains antiferromagnetic while the bulk exhibits ferromagnetic
ordering.


title:
Degree distribution of the visibility graphs mapped from fractional
  Brownian motions and multifractal random walks

abstract:
  The dynamics of a complex system is usually recorded in the form of time
series, which can be studied through its visibility graph from a complex
network perspective. We investigate the visibility graphs extracted from
fractional Brownian motions and multifractal random walks, and find that the
degree distributions exhibit power-law behaviors, in which the power-law
exponent $\alpha$ is a linear function of the Hurst index $H$ of the time
series. We also find that the degree distribution of the visibility graph is
mainly determined by the temporal correlation of the original time series with
minor influence from the possible multifractal nature. As an example, we study
the visibility graphs constructed from two Chinese stock market indexes and
unveil that the degree distributions have power-law tails, where the tail
exponents of the visibility graphs and the Hurst indexes of the indexes are
close to the $\alpha\sim H$ linear relationship.


title:
Impurity-induced in-gap state and Tc in sign-reversing s-wave
  superconductors: analysis of iron oxypnictide superconductors

abstract:
  The sign-reversing fully gapped superconducting state, which is expected to
be realized in oxypnictide superconductors, can be prominently affected by
nonmagnetic impurities due to the interband scattering of Cooper pairs. We
study this problem based on the isotropic two-band BCS model: In oxypnictide
superconductors, the interband impurity scattering $I'$ is not equal to the
intraband one $I$. In the Born scattering regime, the reduction in Tc is
sizable and the impurity-induced density of states (DOS) is prominent if $I\sim
I'$, due to the interband scattering. Although impurity-induced DOS can yield a
power-law temperature dependence in $1/T_1$, a sizable suppression in Tc is
inevitably accompanied. In the unitary scattering regime, in contrast, impurity
effect is very small for both Tc and DOS except at $I=I'$. By comparing theory
and experiments, we expect that the degree of anisotropy in the $s_\pm$-wave
gap function strongly depends on compounds.


title: Distances and Stellar Population properties using the SBF method

abstract:
  We present some results on the study of stellar population properties and
distances of galaxies using the SBF technique. The applications summarized here
show that the Surface Brightness Fluctuations (SBF) method is able to i)
provide accurate distances of resolved and unresolved stellar systems from ~10
Kpc to ~150 Mpc, and ii) to reliably constrain the physical properties (e.g.
age and metallicity) of unresolved stellar systems.


title: A Relativistic Electron-Positron Outflow from a Tepid Fireball

abstract:
  Through detailed numerical simulations, we demonstrate that relativistic
outflows (Lorentz factor $\Gamma \sim 7$) of electron-positron pairs can be
produced by radiative acceleration even when the flow starts from a nearly pair
equilibrium state at subrelativistic temperatures. Contrary to the expectation
that pairs annihilate during an expansion stage for such low temperatures, we
find that most pairs can survive for the situations obtained in our previous
work. This is because in the outflow-generating region the dynamical timescale
is short enough even though the fireball is optically thick to scattering.
Several problems that should be solved to apply to actual active galactic
nucleus jets are discussed.


title:
Family Gauge Symmetry as an Origin of Koide's Mass Formula and Charged
  Lepton Spectrum

abstract:
  Koide's mass formula is an empirical relation among the charged lepton masses
which holds with a striking precision. We present a model of charged lepton
sector within an effective field theory with U(3) \times SU(2) family gauge
symmetry, which predicts Koide's formula within the present experimental
accuracy. Radiative corrections as well as other corrections to Koide's mass
formula have been taken into account. We adopt a known mechanism, through which
the charged lepton spectrum is determined by the vacuum expectation value of a
9-component scalar field \Phi. On the basis of this mechanism, we implement the
following mechanisms into our model: (1) The radiative correction induced by
family gauge interaction cancels the QED radiative correction to Koide's mass
formula, assuming a scenario in which the U(3) family gauge symmetry and
SU(2)_L weak gauge symmetry are unified at 10^2-10^3 TeV scale; (2) A simple
potential of \Phi invariant under U(3) \times SU(2) leads to a realistic
charged lepton spectrum, consistent with the experimental values, assuming that
Koide's formula is protected; (3) Koide's formula is stabilized by embedding
U(3) \times SU(2) symmetry in a larger symmetry group. Formally fine tuning of
parameters in the model is circumvented (apart from two exceptions) by
appropriately connecting the charged lepton spectrum to the boundary (initial)
conditions of the model at the cut-off scale.


title: Non-Extensive Approach to Quark Matter

abstract:
  We review the idea of generating non-extensive stationary distributions based
on abstract composition rules for the subsystem energies, in particular the
relativistic generalized Boltzmann equation method. The thermodynamical
behavior of such systems is investigated and hadron spectra stemming from
relativistic heavy ion collisions are calculated by assuming quark coalescence.


title: Heavy quark medium polarization at next-to-leading order

abstract:
  We compute the imaginary part of the heavy quark contribution to the photon
polarization tensor, i.e. the quarkonium spectral function in the vector
channel, at next-to-leading order in thermal QCD. Matching our result, which is
valid sufficiently far away from the two-quark threshold, with a previously
determined resummed expression, which is valid close to the threshold, we
obtain a phenomenological estimate for the spectral function valid for all
non-zero energies. In particular, the new expression allows to fix the overall
normalization of the previous resummed one. Our result may be helpful for
lattice reconstructions of the spectral function (near the continuum limit),
which necessitate its high energy behaviour as input, and can in principle also
be compared with the dilepton production rate measured in heavy ion collision
experiments. In an appendix analogous results are given for the scalar channel.


title: Gauge Coupling Unification in MSSM + 5 Flavors

abstract:
  We investigate gauge coupling unification at 2-loops for theories with 5
extra vectorlike SU(5) fundamentals added to the MSSM. This is a borderline
case where unification is only predicted in certain regions of parameter space.
We establish a lower bound on the scale for the masses of the extra flavors, as
a function of the sparticle masses. Models far outside of the bound do not
predict unification at all (but may be compatible with unification), and models
outside but near the boundary cannot reliably claim to predict it with an
accuracy comparable to the MSSM prediction. Models inside the boundary can work
just as well as the MSSM.


title: Mobility variations in mono- and multi-layer graphene films

abstract:
  The electric properties of mono- and multi-layer graphene films were
systematically studied with the layer number determined by their optical
contrast. The current modulation increased monotonically with a decrease in the
layer number due to the reduction of the interlayer scattering. Carrier
mobility in the monolayer was significantly greater than that in the multilayer
due to linear dispersion relation. On the other hand, in the monolayer, carrier
transport was extremely sensitive to charged impurity density due to the
reduction in screening effect, which causes larger mobility variation.
Reduction of the charged impurity density is thus key for high mobility.


title:
Some remarks on the size of tubular neighborhoods in contact topology
  and fillability

abstract:
  The well-known tubular neighborhood theorem for contact submanifolds states
that a small enough neighborhood of such a submanifold N is uniquely determined
by the contact structure on N, and the conformal symplectic structure of the
normal bundle. In particular, if the submanifold N has trivial normal bundle
then its tubular neighborhood will be contactomorphic to a neighborhood of
Nx{0} in the model space NxR^{2k}.
  In this article we make the observation that if (N,\xi_N) is a 3-dimensional
overtwisted submanifold with trivial normal bundle in (M,\xi), and if its model
neighborhood is sufficiently large, then (M,\xi) does not admit an exact
symplectic filling.


title:
Dynamical Origins for Non-Gaussian Vorticity Distributions in Turbulent
  Flows

abstract:
  We present results on the connection between the vorticity equation and the
shape of the single-point vorticity PDF. The statistical framework for these
observations is cast in form of conditional averages. The numerical evaluation
of these conditional averages provides insights into the intimate relation of
dynamical effects like vortex stretching and vorticity diffusion and
non-Gaussian vorticity statistics.


title: Effect of a strong laser on spin precession

abstract:
  The semiclassical dynamics of a charged spin-1/2 particle in an intense
electromagnetic plane wave is analyzed beyond the electric dipole approximation
and taking into account the leading relativistic corrections to the Pauli
equation. It is argued that the adiabatic spin evolution driven by a low
intensity radiation changes its character drastically as an intensity of a
laser is increasing. Particularly, it is shown that a charged particle exposes
a spin flip resonance at a certain pick value of a laser field strength, which
is determined by a particle's gyromagnetic ratio.


title: The space of closed subgroups of $R^n$

abstract:
  The Chabauty space of a topological group is the set of its closed subgroups,
endowed with a natural topology. As soon as $n>2$, the Chabauty space of $R^n$
has a rather intricate topology and is not a manifold. By an investigation of
its local structure, we fit it into a wider, but too wild, class of topological
spaces (namely Goresky-MacPherson stratified spaces). Thanks to a localization
theorem, this local study also leads to the main result of this article: the
Chabauty space of $R^n$ is simply connected for all $n$. Last, we give an
alternative proof of the Hubbard-Pourezza Theorem, which describes the Chabauty
space of $R^2$.


title: Locally definable homotopy

abstract:
  In "On o-minimal homotopy groups", o-minimal homotopy was developed for the
definable category, proving o-minimal versions of the Hurewicz theorems and the
Whitehead theorem. Here, we extend these results to the category of locally
definable spaces, for which we introduce homology and homotopy functors. We
also study the concept of connectedness in V-definable groups -- which are
examples of locally definable spaces. We show that the various concepts of
connectedness associated to these groups, which have appeared in the
literature, are non-equivalent.


title: Simple Classification of Light Baryons

abstract:
  We introduce a classification number $n$ which describes the baryon mass
information in a fuzzy manner. According to $n$ and $J^p$ of baryons, we put
all known light baryons in a simple table in which some baryons with same ($n$,
$J^p$) are classified as members of known octets or decuplets. Meanwhile, we
predict two new possible octets.


title: Vanishing Cycles in Holomorphic Foliations by Curves and Foliated Shells

abstract:
  The purpose of this paper is the study of vanishing cycles in holomorphic
foliations by complex curves on compact complex manifolds. The main result
consists in showing that a vanishing cycle comes together with a much richer
complex geometric object - we call this object a foliated shell.


title:
Performance of a greedy algorithm for edge covering by cliques in
  interval graphs

abstract:
  In this paper a greedy algorithm to detect conflict cliques in interval
graphs and circular-arc graphs is analyzed. In a graph, a stable set requires
that at most one vertex is chosen for each edge. It is equivalent to requiring
that at most one vertex for each maximal clique is chosen. We show that this
algorithm finds all maximal cliques for interval graphs, i.e. it can compute
the convex hull of the stable set polytope. In case of circular-arc graphs, the
algorithm is not able to detect all maximal cliques, yet remaining correct.
This problem occurs in the context of railway scheduling. A train requests the
allocation of a railway infrastructure resource for a specific time interval.
As one is looking for conflict-free train schedules, the used resource
allocation intervals in a schedule must not overlap. The conflict-free choices
of used intervals for each resource correspond to stable sets in the interval
graph associated to the allocation time intervals.


title:
Masses of light tetraquarks and scalar mesons in the relativistic quark
  model

abstract:
  Masses of the ground state light tetraquarks are dynamically calculated in
the framework of the relativistic diquark-antidiquark picture. The internal
structure of the diquark is taken into account by calculating the form factor
of the diquark-gluon interaction in terms of the overlap integral of the
diquark wave functions. It is found that scalar mesons with masses below 1 GeV:
f_0(600) (\sigma), K^*_0(800) (\kappa), f_0(980) and a_0(980) agree well with
the light tetraquark interpretation.


title:
Memory effect in triglycine sulfate induced by a transverse electric
  field: specific heat measurement

abstract:
  The influence of a transverse electric field in the specific heat of
triglycine sulphate (TGS) has been studied. The specific heat of TGS has been
measured heating the sample from ferroelectric to paraelectric phase after
prolonged transverse electric field (i.e. perpendicular to the ferroelectric
axis). It is shown that the specific heat of TGS can remember the temperature
$T_s$ at which the transverse field was previously applied.


title:
Collision and fusion of counterpropagating micron-sized optical beams in
  non-uniformly biased photorefractive crystals

abstract:
  We theoretically investigate collision of optical beams travelling in
opposite directions through a centrosymmetric photorefractive crystal biased by
a spatially non-uniform voltage. We analytically predict the fusion of
counterpropagating solitons in conditions in which the applied voltage is
rapidly modulated along the propagation axis, so that self-bending is
suppressed by the "restoring symmetry" mechanism. Moreover, when the applied
voltage is slowly modulated, we predict that the modified self-bending allows
conditions in which the two beams fuse together, forming a curved light-channel
splice.


title:
Coarsening Dynamics of an Antiferromagnetic XY model on the Kagome
  Lattice: Breakdown of the Critical Dynamic Scaling

abstract:
  We find a breakdown of the critical dynamic scaling in the coarsening
dynamics of an antiferromagnetic {\em XY} model on the kagome lattice when the
system is quenched from disordered states into the Kosterlitz-Thouless ({\em
KT}) phases at low temperatures. There exist multiple growing length scales:
the length scales of the average separation between fractional vortices are
found to be {\em not} proportional to the length scales of the quasi-ordered
domains. They are instead related through a nontrivial power-law relation. The
length scale of the quasi-ordered domains (as determined from optimal collapse
of the correlation functions for the order parameter $\exp[3 i \theta (r)]$)
does not follow a simple power law growth but exhibits an anomalous growth with
time-dependent effective growth exponent. The breakdown of the critical dynamic
scaling is accompanied by unusual relaxation dynamics in the decay of
fractional ($3\theta$) vortices, where the decay of the vortex numbers is
characterized by an exponential function of logarithmic powers in time.


title: Large hierarchies from approximate R symmetries

abstract:
  We show that hierarchically small vacuum expectation values of the
superpotential in supersymmetric theories can be a consequence of an
approximate R symmetry. We briefly discuss the role of such small constants in
moduli stabilization and understanding the huge hierarchy between the Planck
and electroweak scales.


title: Laws of Black Hole Mechanics from Holst Action

abstract:
  The formulation of Weak Isolated Horizons (WIH) based on the Isolated Horizon
formulation of black hole horizons is reconsidered. The first part of the paper
deals with the derivation of laws of mechanics of a WIH. While the zeroth law
follows from the WIH boundary conditions, first law depends on the action
chosen. We construct the covariant phase space for a spacetime having an WIH as
inner boundary for the Holst action. This requires the introduction of new
potential functions so that the symplectic structure is foliation independent.
We show that a precise cancellation among various terms leads to the usual
first law for WIH. Subsequently, we show from the same covariant phase space
that for spherical horizons, the topological theory on the inner boundary is a
U(1) Chern-Simons theory.


title:
Multiplicative formulas in Cohomology of $G/P$ and in quiver
  representations

abstract:
  Consider a partial flag variety $X$ which is not a grassmaninan. Consider
also its cohomology ring ${\rm H}^*(X,\ZZ)$ endowed with the base formed by the
Poincar\'e dual classes of the Schubert varieties. In
\cite{Richmond:recursion}, E. Richmond showed that some coefficient structure
of the product in ${\rm H}^*(X,\ZZ)$ are products of two such coefficients for
smaller flag varieties. Consider now a quiver without oriented cycle. If
$\alpha$ and $\beta$ denote two dimension-vectors, $\alpha\circ\beta$ denotes
the number of $\alpha$-dimensional subrepresentations of a general
$\alpha+\beta$-dimensional representation. In \cite{DW:comb}, H. Derksen and J.
Weyman expressed some numbers $\alpha\circ\beta$ as products of two smaller
such numbers. The aim of this work is to prove two generalisations of the two
above results by the same way.


title:
Optical readout tracking detector concept using secondary scintillation
  from liquid argon generated by a thick gas electron multiplier

abstract:
  For the first time secondary scintillation, generated within the holes of a
thick gas electron multiplier (TGEM) immersed in liquid argon, has been
observed and measured using a silicon photomultiplier device (SiPM). 250
electron-ion pairs, generated in liquid argon via the interaction of a 5.9KeV
Fe-55 gamma source, were drifted under the influence of a 2.5KV/cm field
towards a 1.5mm thickness TGEM, the local field sufficiently high to generate
secondary scintillation light within the liquid as the charge traversed the
central region of the TGEM hole. The resulting VUV light was incident on an
immersed SiPM device coated in the waveshifter tetraphenyl butadiene (TPB), the
emission spectrum peaked at 460nm in the high quantum efficiency region of the
device. For a SiPM over-voltage of 1V, a TGEM voltage of 9.91KV, and a drift
field of 2.5KV/cm, a total of 62 photoelectrons were produced at the SiPM
device per Fe-55 event, corresponding to an estimated gain of 150
photoelectrons per drifted electron.


title: On a property of branching coefficients for affine Lie algebras

abstract:
  It is demonstrated that decompositions of integrable highest weight modules
of a simple Lie algebra with respect to its reductive subalgebra obey the set
of algebraic relations leading to the recursive properties for the
corresponding branching coefficients. These properties are encoded in the
special element (of the formal algebra E(g)) Gamma_(a ->g) that describes the
injection and is called the fan. In the simplest case, when "a" is a Cartan
subalgebra of g, the recursion procedure generates the weight diagram of the
module L(g). When applied to a reduction of highest weight modules the
recursion described by the fan provides a highly effective tool to obtain the
explicit values of branching coefficients.


title:
Turbulent magnetic fields in the quiet Sun: implications of Hinode
  observations and small-scale dynamo simulations

abstract:
  Using turbulent MHD simulations (magnetic Reynolds numbers up to 8000) and
Hinode observations, we study effects of turbulence on measuring the solar
magnetic field outside active regions. Firstly, from synthetic Stokes V
profiles for the FeI lines at 630.1 and 630.2 nm, we show that a peaked
probability distribution function (PDF) for observationally-derived field
estimates is consistent with a monotonic PDF for actual vertical field
strengths. Hence, the prevalence of weak fields is greater than would be
naively inferred from observations. Secondly, we employ the fractal
self-similar geometry of the turbulent solar magnetic field to derive two
estimates (numerical and observational) of the true mean vertical unsigned flux
density. We also find observational evidence that the scales of magnetic
structuring in the photosphere extend at least down to an order of magnitude
smaller than 200 km: the self-similar power-law scaling in the signed measure
from a Hinode magnetogram ranges (over two decades in length scales and
including the granulation scale) down to the 200 km resolution limit. From the
self-similar scaling, we determine a lower bound for the true quiet-Sun mean
vertical unsigned flux density of ~50 G. This is consistent with our
numerically-based estimates that 80% or more of the vertical unsigned flux
should be invisible to Stokes-V observations at a resolution of 200 km owing to
the cancellation of signal from opposite magnetic polarities. Our estimates
significantly reduce the order-of-magnitude discrepancy between Zeeman- and
Hanle-based estimates.


title: Geodesic Webs of Hypersurfaces

abstract:
  In the present paper we study geometric structures associated with webs of
hypersurfaces. We prove that with any geodesic (n+2)-web on an n-dimensional
manifold there is naturally associated a unique projective structure and,
provided that one of web foliations is pointed, there is also associated a
unique affine structure. The projective structure can be chosen by the claim
that the leaves of all web foliations are totally geodesic, and the affine
structure by an additional claim that one of web functions is affine.
  These structures allow us to determine differential invariants of geodesic
webs and give geometrically clear answers to some classical problems of the web
theory such as the web linearization and the Gronwall theorem.


title:
Classical spin systems and the quantum stabilizer formalism: general
  mappings and applications

abstract:
  We present general mappings between classical spin systems and quantum
physics. More precisely, we show how to express partition functions and
correlation functions of arbitrary classical spin models as inner products
between quantum stabilizer states and product states, thereby generalizing
mappings for some specific models established in [Phys. Rev. Lett. 98, 117207
(2007)]. For Ising- and Potts-type models with and without external magnetic
field, we show how the entanglement features of the corresponding stabilizer
states are related to the interaction pattern of the classical model, while the
choice of product states encodes the details of interaction. These mappings
establish a link between the fields of classical statistical mechanics and
quantum information theory, which we utilize to transfer techniques and methods
developed in one field to gain insight into the other. For example, we use
quantum information techniques to recover well known duality relations and
local symmetries of classical models in a simple way, and provide new classical
simulation methods to simulate certain types of classical spin models. We show
that in this way all inhomogeneous models of q-dimensional spins with pairwise
interaction pattern specified by a graph of bounded tree-width can be simulated
efficiently. Finally, we show relations between classical spin models and
measurement-based quantum computation.


title: Ultrasonic studies of the magnetic phase transition in MnSi

abstract:
  Measurements of the sound velocities in a single crystal of MnSi were
performed in the temperature range 4-150 K. Elastic constants, controlling
propagation of longitudinal waves reveal significant softening at a temperature
of about 29.6 K and small discontinuities at $\sim$28.8 K, which corresponds to
the magnetic phase transition in MnSi. In contrast the shear elastic moduli do
not show any softening at all, reacting only to the small volume deformation
caused by the magneto-volume effect. The current ultrasonic study exposes an
important fact that the magnetic phase transition in MnSi, occurring at 28.8 K,
is just a minor feature of the global transformation marked by the rounded
maxima or minima of heat capacity, thermal expansion coefficient, sound
velocities and absorption, and the temperature derivative of resistivity.


title:
Factorization property of generalized s-selfdecomposable measures and
  class $L^f$ distributions$^1$

abstract:
  The method of \emph{random integral representation}, that is, the method of
representing a given probability measure as the probability distribution of
some random integral, was quite successful in the past few decades. In this
note we will find such a representation for generalized s-selfdecomposable and
selfdecomposable distributions that have the \emph{factorization property}.
These are the classes $\mathcal{U}^f_{\be}$ and $L^f$, respectively


title:
Entanglement of systems of dipolar coupled nuclear spins at the
  adiabatic demagnetization

abstract:
  We consider the adiabatic demagnetization in the rotating reference frame
(ADRF) of a system of dipolar coupled nuclear spins $s=1/2$ in the external
magnetic field. The demagnetization starts with the offset of the external
magnetic field (in frequency units) from the Larmor frequency being several
times greater than the local dipolar field. For different subsystem sizes, we
have found from numerical simulations the temperatures at which subsystems of a
one-dimensional nine-spin chain and a plane nine-spin cluster become entangled.
These temperatures are of the order of microkelvins and are almost independent
of the subsystem size. There is a weak dependence of the temperature on the
space dimension of the system.


title: Optical conductivity in the t-J-Holstein Model

abstract:
  Using recently developed numerical method we compute charge stiffness and
optical conductivity of the t-J model coupled to optical phonons. Coherent hole
motion is most strongly influenced by the electron-phonon coupling within the
physically relevant regime of the exchange interaction. We find unusual
non-monotonous dependence of the charge stiffness as a function of the exchange
coupling near the crossover to the strong electron-phonon coupling regime.
Optical conductivity in this regime shows a two-peak structure. The
low-frequency peak represents local magnetic excitation, attached to the hole,
while the higher-frequency peak corresponds to the mid infrared band that
originates from coupling to spin-wave excitations, broadened and renormalized
by phonon excitations. We observe no separate peak at or slightly above the
phonon frequency. This finding suggests that the two peak structure seen in
recent optical measurements is due to magnetic excitations coupled to lattice
degrees of freedom via doped charge carriers.


title: Lowest Weights in Cohomology of Variations of Hodge Structure (II)

abstract:
  Let $X$ be an irreducible complex analytic space with $j:U\into X$ an
immersion of a smooth Zariski open subset, and let $\bV$ be a variation of
Hodge structure of weight $n$ over $U$. Assume $X$ is compact K\"ahler. Then
provided the local monodromy operators at infinity are quasi-unipotent,
$IH^k(X, \bV)$ is known to carry a pure Hodge structure of weight $k+n$, while
$H^k(U,\bV)$ carries a mixed Hodge structure of weight $\ge k+n$. In this note
it is shown that the image of the natural map $IH^k(X,\bV) \to H^k(U,\bV)$ is
the lowest weight part of this mixed Hodge structure. In the algebraic case
this easily follows from the formalism of mixed sheaves, but the analytic case
is rather complicated, in particular when the complement $X-U$ is not a
hypersurface.


title: On flavor violation for massive and mixed neutrinos

abstract:
  We discuss flavor charges and states for interacting mixed neutrinos in QFT.
We show that the Pontecorvo states are not eigenstates of the flavor charges.
This implies that their use in describing the flavor neutrinos produces a
violation of lepton charge conservation in the production/detection vertices.
The flavor states defined as eigenstates of the flavor charges give the correct
representation of mixed neutrinos in charged current weak interaction
processes.


title: A complete reduction of one-loop tensor 5- and 6-point integrals

abstract:
  We perform a complete analytical reduction of general one-loop Feynman
integrals with five and six external legs for tensors up to rank R=3 and 4,
respectively. An elegant formalism with extensive use of signed minors is
developed for the cancellation of inverse Gram determinants. The 6-point tensor
functions of rank R are expressed in terms of 5-point tensor functions of rank
R-1, and the latter are reduced to scalar four-, three-, and two-point
functions. The resulting compact formulae allow both for a study of analytical
properties and for efficient numerical programming. They are implemented in
Fortran and Mathematica.


title: Strong fields induce ultrafast rearrangement of H-atoms in H$_2$O

abstract:
  H-atoms in H$_2$O are rearranged by strong optical fields generated by
intense, 10 fs laser pulses to form H$_2^+$, against prevailing wisdom that
strong fields inevitably lead to multiple molecular ionization and the
subsequent Coulomb explosion into fragments. This atomic rearrangement is shown
to occur within a single 10 fs pulse. Comparison with results obtained with
$\sim$300-attosecond long strong fields generated using fast Si$^{8+}$ ions
helps establish thresholds for field strength and time required for such
rearrangements. Quantum-chemical calculations reveal that H$_2^+$ originates in
the $^1$A state of H$_2$O$^{2+}$ when the O-H bond elongates to 1.15 a.u. and
the H-O-H angle becomes 120$^o$. Bond formation on the ultrafast timescale of
molecular vibrations (10 fs for H$_2^+$) has hitherto not been reported.


title:
On the possibility to observe higher $n^3D_1$ bottomonium states in the
  $e^+e^-$ processes

abstract:
  The possibility to observe new bottomonium states with $J^{PC}= 1^{--}$ in
the region $10.7-11.1$ GeV is discussed. The analysis of the di-electron widths
shows that the $(n+1)^3S_1$ and $n^3D_1$ states ($n\geq 3$) may be mixed with a
rather large mixing angle, $\theta\sim30^\circ$ and this effect provides the
correct values of $\Gamma_{ee}(\Upsilon(10580))$ and
$\Gamma_{ee}(\Upsilon(11020))$. On the other hand, the $S-D$ mixing gives rise
to an increase by two orders of magnitude of the di-electron widths of the
mixed $\tilde\Upsilon(n^3D_1$) resonances ($n=3,4,5$), which originate from
pure $D-$wave states. The value
$\Gamma_{ee}(\tilde\Upsilon(3D))=0.095^{+0.028}_{-0.025}$ keV is obtained,
being only $\sim 3$ times smaller than the di-electron width of
$\Upsilon(10580)$, while $\Gamma_{ee}(\tilde\Upsilon(5D))\sim 135$ eV appears
to be close to $\Gamma_{ee}(\Upsilon(11020))$ and therefore this resonance may
become manifest in the $e^+e^-$ experiments. The mass differences between
$M(nD)$ and $M((n+1)S) (n=4,5)$ are shown to be rather small, $50\pm 10$ MeV.


title:
A Factor 3/2 Approximation for Generalized Steiner Tree Problem with
  Distances One and Two

abstract:
  We design a 3/2 approximation algorithm for the Generalized Steiner Tree
problem (GST) in metrics with distances 1 and 2. This is the first polynomial
time approximation algorithm for a wide class of non-geometric metric GST
instances with approximation factor below 2.


title:
Exact $f(R)$-cosmological model coming from the request of the existence
  of a Noether symmetry

abstract:
  We present an $f(R)$-cosmological model with an exact analytic solution,
coming from the request of the existence of a Noether symmetry, which is able
to describe a dust-dominated decelerated phase before the current accelerated
phase of the universe.


title: Binarity and multiperiodicity in high-amplitude delta Scuti stars

abstract:
  We have carried out a photometric and spectroscopic survey of bright
high-amplitude delta Scuti (HADS) stars. The aim was to detect binarity and
multiperiodicity (or both) in order to explore the possibility of combining
binary star astrophysics with stellar oscillations. Here we present the first
results for ten, predominantly southern, HADS variables. We detected the
orbital motion of RS Gru with a semi-amplitude of ~6.5 km/s and 11.5 days
period. The companion is inferred to be a low-mass dwarf star in a close orbit
around RS Gru. We found multiperiodicity in RY Lep both from photometric and
radial velocity data and detected orbital motion in the radial velocities with
hints of a possible period of 500--700 days. The data also revealed that the
amplitude of the secondary frequency is variable on the time-scale of a few
years, whereas the dominant mode is stable. Radial velocities of AD CMi
revealed cycle-to-cycle variations which might be due to non-radial pulsations.
We confirmed the multiperiodic nature of BQ Ind, while we obtained the first
radial velocity curves of ZZ Mic and BE Lyn. The radial velocity curve and the
O-C diagram of CY Aqr are consistent with the long-period binary hypothesis. We
took new time series photometry on XX Cyg, DY Her and DY Peg, with which we
updated their O-C diagrams.


title: Final state interaction in $K\to 2\pi$ decay

abstract:
  Contrary to wide-spread opinion that the final state interaction (FSI)
enhances the amplitude $<2\pi;I=0|K^0>$, we argue that FSI does not increase
the absolute value of this amplitude.


title:
Analysis of Discrete Signals with Stochastic Components using Flicker
  Noise Spectroscopy

abstract:
  The problem of information extraction from discrete stochastic time series,
produced with some finite sampling frequency, using flicker-noise spectroscopy,
a general framework for information extraction based on the analysis of the
correlation links between signal irregularities and formulated for continuous
signals, is discussed. It is shown that the mathematical notions of Dirac and
Heaviside functions used in the analysis of continuous signals may be
interpreted as high-frequency and low-frequency stochastic components,
respectively, in the case of discrete series. The analysis of
electroencephalogram measurements for a teenager with schizophrenic symptoms at
two different sampling frequencies demonstrates that the "power spectrum" and
difference moment contain different information in the case of discrete
signals, which was formally proven for continuous signals. The sampling
interval itself is suggested as an additional parameter that should be included
in general parameterization procedures for real signals.


title:
Quantum limits in the measurement of very small displacements in optical
  images

abstract:
  We consider the problem of the measurement of very small displacements in the
transverse plane of an optical image with a split photodetector. We show that
the standard quantum limit for such a measurement, which is equal to the
diffraction limit divided by the square root of the number of photons used in
the measurement, cannot be overcome by use of ordinary single-mode squeezed
light. We give the form of possible multimode nonclassical states of light,
enabling us to enhance by orders of magnitude the resolution of such a
measurement beyond the standard quantum limit.


title: Exotic Bialgebras from 9x9 Unitary Braid Matrices

abstract: We present the exotic bialgebras that arise from a 9x9 unitary braid matrix.


title:
Inclusive electron scattering from nuclei in the quasielastic region at
  large momentum transfer

abstract:
  Experiment E02-019, performed in Hall C at the Thomas Jefferson National
Accelerator Facility (TJNAF), was a measurement of inclusive electron cross
sections for several nuclei ($^{2}$H,$^{3}$He, $^{4}$He, $^{9}$Be,$^{12}$C,
$^{63}$Cu, and $^{197}$Au) in the quasielastic region at high momentum
transfer.
  In the region of low energy transfer, the cross sections were analyzed in
terms of the reduced response, F(y), by examining its $y$-scaling behavior. The
data were also examined in terms of the nuclear structure function $\nu W_2^A$
and its behavior in $x$ and the Nachtmann variable $\xi$. The data show
approximate scaling of $\nu W_2^A$ in $\xi$ for all targets at all kinematics,
unlike scaling in $x$, which is confined to the DIS regime. However,
$y$-scaling observations are limited to the kinematic region dominated by the
quasielastic response ({$y<$0}), where some scaling violations arising from
FSIs are observed.


title: Vorticity internal transition layers for the Navier-Stokes equations

abstract:
  We deal with the incompressible Navier-Stokes equations, in two and three
dimensions, when some vortex patches are prescribed as initial data i.e. when
there is an internal boundary across which the vorticity is discontinuous. We
show -thanks to an asymptotic expansion- that there is a sharp but smooth
variation of the fluid vorticity into a internal layer moving with the flow of
the Euler equations; as long as this later exists and as t * nu is small, where
nu is the viscosity coefficient.


title: Teff and logg dependence of FeH in M-dwarfs

abstract:
  We present synthetic FeH band spectra in the z-filter range for several
M-dwarf models with logg=3.0-5.0 [cgs] and Teff=2800K -3450K. Our aim is to
characterize convective velocities in M-dwarfs and to give a rough estimate of
the range in which 3D-atmosphere treatment is necessary and where 1D-atmosphere
models suffice for the interpretation of molecular spectral features. This is
also important in order to distinguish between the velocity-broadening and the
rotational- or Zeeman-broadening. The synthetic spectra were calculated using
3D CO5BOLD radiative-hydrodynamic (RHD) models and the line synthesis code
LINFOR3D. We used complete 3D-models and high resolution 3D spectral synthesis
for the detailed study of some well isolated FeH lines. The FeH line strength
shows a dependence on surface gravity and effective temperature and could be
employed to measure both quantities in M-type objects. The line width is
related to the velocity-field in the model stars, which depends strongly on
surface gravity. Furthermore, we investigate the velocity-field in the 3D
M-dwarf models together with the related micro- and macro-turbulent velocities
in the 1D case. We also search for effects on the lineshapes.


title:
Reducible connections and non-local symmetries of the self-dual
  Yang-Mills equations

abstract:
  We construct the most general reducible connection that satisfies the
self-dual Yang-Mills equations on a simply connected, open subset of flat
$\mathbb{R}^4$. We show how all such connections lie in the orbit of the flat
connection on $\mathbb{R}^4$ under the action of non-local symmetries of the
self-dual Yang-Mills equations. Such connections fit naturally inside a larger
class of solutions to the self-dual Yang-Mills equations that are analogous to
harmonic maps of finite type.


title:
On properties of Continuous-Time Random Walks with Non-Poissonian
  jump-times

abstract:
  The usual development of the continuous-time random walk (CTRW) proceeds by
assuming that the present is one of the jumping times. Under this restrictive
assumption integral equations for the propagator and mean escape times have
been derived. We generalize these results to the case when the present is an
arbitrary time by recourse to renewal theory. The case of Erlang distributed
times is analyzed in detail. Several concrete examples are considered.


title: Driving mechanism in massive B-type pulsators

abstract:
  After a historical introduction, I present the current status of our
understanding of the mechanism responsible for pulsation in Beta Cephei and SPB
stars.


title:
Can the cosmic-ray driven dynamo model explain the observations of the
  polarized emission of edge-on galaxies ?

abstract:
  In the present paper we construct maps of polarized synchrotron radio
emission of a whole galaxy, based on local models of the cosmic ray (CR) driven
dynamo. We perform numerical simulations of the dynamo in local Cartesian
domains, with shear-periodic boundary conditions, placed at the different
galactocentric radii. Those local solutions are concatenated together to
construct the synchrotron images of the whole galaxy. The main aim of the paper
is to compare the model results with the observed radio continuum emission from
nearly edge-on spiral galaxy. On the basis of the modeled evolution of the
magnetic field structure, the polarization maps can be calculated at different
time-steps and at any orientation of the modeled galaxy. For the first time a
self-consistent cosmic-ray electron distribution is used to integrate
synchrotron emissivity along the line of sight. Finally, our maps are convolved
with the given radiotelescope beam. We show that it is possible to reconstruct
the extended magnetic halo structures of the edge-on galaxies (so called
X-shaped structures).


title: Quantum Zeno switch for single-photon coherent transport

abstract:
  Using a dynamical quantum Zeno effect, we propose a general approach to
control the coupling between a two-level system (TLS) and its surroundings, by
modulating the energy level spacing of the TLS with a high frequency signal. We
show that the TLS--surroundings interaction can be turned on or off when the
ratio between the amplitude and the frequency of the modulating field is
adjusted to be a zero of a Bessel function. The quantum Zeno effect of the TLS
can also be observed by the vanishing of the photon reflection at these zeros.
Based on these results, we propose a quantum switch to control the transport of
a single photon in a 1D waveguide. Our analytical results agree well with
numerical results using Floquet theory.


title: Bounds states of the Schr\"odinger-Newton model in low dimensions

abstract:
  We prove the existence of quasi-stationary symmetric solutions with exactly
n>=0 zeros and uniqueness for n=0 for the Schr\"odinger-Newton model in one
dimension and in two dimensions along with an angular momentum m>=0. Our result
is based on an analysis of the corresponding system of second-order
differential equations.


title:
Spectral Pollution and How to Avoid It (With Applications to Dirac and
  Periodic Schr\"odinger Operators)

abstract:
  This paper, devoted to the study of spectral pollution, contains both
abstract results and applications to some self-adjoint operators with a gap in
their essential spectrum occuring in Quantum Mechanics. First we consider
Galerkin basis which respect the decomposition of the ambient Hilbert space
into a direct sum $H=PH\oplus(1-P)H$, given by a fixed orthogonal projector
$P$, and we localize the polluted spectrum exactly. This is followed by
applications to periodic Schr\"odinger operators (pollution is absent in a
Wannier-type basis), and to Dirac operator (several natural decompositions are
considered). In the second part, we add the constraint that within the Galerkin
basis there is a certain relation between vectors in $PH$ and vectors in
$(1-P)H$. Abstract results are proved and applied to several practical methods
like the famous "kinetic balance" of relativistic Quantum Mechanics.


title: Reliability of the detection of the Baryon Acoustic Peak

abstract:
  The correlation function of the distribution of matter in the universe shows,
at large scales, baryon acoustic oscillations, which were imprinted prior to
recombination. This feature was first detected in the correlation function of
the luminous red galaxies (LRG) of the Sloan Digital Sky Survey (SDSS). The
final release (DR7) of the SDSS has been recently made available, and the
useful volume is about two times bigger than in the old sample. We present
here, for the first time, the redshift space correlation function of this
sample at large scales together with that for one shallower, but denser
volume-limited subsample drawn from the 2dF redshift survey. We test the
reliability of the detection of the acoustic peak at about 100 Mpc/h and the
behaviour of the correlation function at larger scales by means of careful
estimation of errors. We confirm the presence of the peak in the latest data
although broader than in previous detections.


title: Pairs of mutually annihilating operators

abstract:
  Pairs (A,B) of mutually annihilating operators AB=BA=0 on a finite
dimensional vector space over an algebraically closed field were classified by
Gelfand and Ponomarev [Russian Math. Surveys 23 (1968) 1-58] by method of
linear relations. The classification of (A,B) over any field was derived by
Nazarova, Roiter, Sergeichuk, and Bondarenko [J. Soviet Math. 3 (1975) 636-654]
from the classification of finitely generated modules over a dyad of two local
Dedekind rings. We give canonical matrices of (A,B) over any field in an
explicit form and our proof is constructive: the matrices of (A,B) are
sequentially reduced to their canonical form by similarity transformations
(A,B)--> S^{-1}AS, S^{-1}BS).


title: On complex nilpotent Leibniz superalgebras of nilindex n+m

abstract:
  We present the description up to isomorphism of Leibniz superalgebras with
characteristic sequence $(n|m_1,...,m_k)$ and nilindex $n+m,$ where $m=m_1+
>...+m_k,$ $n$ and $m$ ($m\neq 0$) are dimensions of even and odd parts,
respectively.


title: Mixed scenario of the charged liquid surface reconstruction

abstract:
  Discussed in the paper is a mixed scenario of the charged liquid surface
reconstruction in the situation where the 2D surface charge density is close to
its saturation value.


title:
Holographic formula for the determinant of the scattering operator in
  thermal AdS

abstract:
  A 'holographic formula' expressing the functional determinant of the
scattering operator in an asymptotically locally anti-de Sitter(ALAdS) space
has been proposed in terms of a relative functional determinant of the scalar
Laplacian in the bulk. It stems from considerations in AdS/CFT correspondence
of a quantum correction to the partition function in the bulk and the
corresponding subleading correction at large N on the boundary. In this paper
we probe this prediction for a class of quotients of hyperbolic space by a
discrete subgroup of isometries. We restrict to the simplest situation of an
abelian group where the quotient geometry describes thermal AdS and also the
non-spinning BTZ instanton. The bulk computation is explicitly done using the
method of images and the answer can be encoded in a (Patterson-)Selberg
zeta-function.


title:
On the moduli space of quadruples of points in the boundary of complex
  hyperbolic space

abstract:
  We consider the space $\mathcal M$ of ordered quadruples of distinct points
in the boundary of complex hyperbolic $n$-space, $\ch{n},$ up to its
holomorphic isometry group ${\rm PU}(n,1).$ One of the important problems in
complex hyperbolic geometry is to construct and describe a moduli space for
$\mathcal M$. For $n=2$, this problem was considered by Falbel, Parker, and
Platis. The main purpose of this paper is to construct a moduli space for
$\mathcal M $ for any dimension $n \geq 1$. The major innovation in our paper
is the use of the Gram matrix instead of a standard position of points.


title:
Minimally doubled chiral fermions with C, P and T symmetry on the
  staggered lattice

abstract:
  Recently, the interest in local lattice actions for chiral fermions has
revived, with the proposition of new local actions in which only the minimal
number of doublers appear. The trigger role of graphene having a minimally
doubled, chirally invariant, Dirac-like excitation spectrum can not be
neglected. The challenge is to construct an action which preserves enough
symmetries to be useful in lattice gauge calculations. We present a new
approach to obtain local lattice actions for fermions using a reinterpretation
of the staggered lattice approach of Kogut and Susskind. This interpretation is
based on the similarity with the staggered lattice approach in FDTD simulations
of acoustics and electromagnetism. It allows us to construct a local action for
chiral fermions which has all discrete symmetries and the minimal number of
fermion flavors, but which is non-Hermitian in real space. However, we argue
that this will not pose a threat to the usability of the theory.


title:
PIERNIK mhd code - a multi-fluid, non-ideal extension of the
  relaxing-TVD scheme (I)

abstract:
  We present a new multi-fluid, grid MHD code PIERNIK, which is based on the
Relaxing TVD scheme. The original scheme has been extended by an addition of
dynamically independent, but interacting fluids: dust and a diffusive cosmic
ray gas, described within the fluid approximation, with an option to add other
fluids in an easy way. The code has been equipped with shearing-box boundary
conditions, and a selfgravity module, Ohmic resistivity module, as well as
other facilities which are useful in astrophysical fluid-dynamical simulations.
The code is parallelized by means of the MPI library. In this paper we shortly
introduce basic elements of the Relaxing TVD MHD algorithm, following Trac &
Pen (2003) and Pen et al. (2003), and then focus on the conservative
implementation of the shearing box model, constructed with the aid of the
Masset's (2000) method. We present results of a test example of a formation of
a gravitationally bounded object (planet) in a self-gravitating and
differentially rotating fluid.


title:
Ni/Ni3C Core-Shell Nanochains and Its Magnetic Properties: One-Step
  Synthesis at low temperature

abstract:
  One-dimensional Ni/Ni3C core-shell nanoball chains with an average diameter
by around 30 nm were synthesized by means of a mild chemical solution method
using a soft template of trioctylphosphineoxide (TOPO). It was revealed that
the uniform Ni nanochains were capped with Ni3C thin shells by about 1 to 4 nm
in thickness and each Ni core consists of polygrains. The coercivity of the
core-shell nanochains is much enhanced (600 Oe at 5 K) and comparable with
single Ni nanowires due to the one-dimensional shape anisotropy. Deriving from
the distinctive structure of Ni core and Ni3C shell, this architecture may
possess a possible bi-functionality. This unique architecture is also useful
for the study on the magnetization reversal mechanism of one-dimensional
magnetic nanostructure.


title:
Constraints on a phenomenologically parameterized neutron-star equation
  of state

abstract:
  We introduce a parameterized high-density equation of state (EOS) in order to
systematize the study of constraints placed by astrophysical observations on
the nature of neutron-star matter. To obtain useful constraints, the number of
parameters should be smaller than the number of neutron-star properties that
have been measured or will have been measured in the next several years. And
the set must be large enough to accurately approximate the large set of
candidate EOSs. We find that a parameterized EOS based on piecewise polytropes
with 3 free parameters matches to about 4% rms error an extensive set of
candidate EOSs at densities below the central density of 1.4 solar mass stars.
Adding observations of more massive stars constrains the higher density part of
the EOS and requires an additional parameter. We obtain constraints on the
allowed parameter space set by causality and by present and near-future
astronomical observations. In particular, we emphasize potentially stringent
constraints on the EOS parameter space associated with two measured properties
of a single star; and we find that a measurement of the moment of inertia of
PSR J0737-3039A can strongly constrain the maximum neutron-star mass. We also
present in an appendix a more efficient algorithm than has previously been used
for finding points of marginal stability and the maximum angular velocity of
stable stars.


title:
Optimization of Decentralized Scheduling for Physic Applications in Grid
  Environments

abstract:
  This paper presents a scheduling framework that is configured for, and used
in physic systems. Our work addresses the problem of scheduling various
computationally intensive and data intensive applications that are required for
extracting information from satellite images. The proposed solution allows
mapping of image processing applications onto available resources. The
scheduling is done at the level of groups of concurrent applications. It
demonstrates a very good behavior for scheduling and executing groups of
applications, while also achieving a near-optimal utilization of the resources.


title:
Stationary isothermic surfaces and some characterizations of the
  hyperplane in the N-dimensional Euclidean space

abstract:
  We consider an entire graph S of a continuous real function over
(N-1)-dimensional Euclidean space with N larger than or equal to 3. Let D be a
domain in N-dimensional Euclidean space with S as a boundary. Consider in D the
heat flow with initial temperature 0 and boundary temperature 1. The problem we
consider is to characterize S in such a way that there exists a stationary
isothermic surface in D. We show that S must be a hyperplane under some general
conditions on S. This is related to Liouville or Bernstein-type theorems for
some elliptic Monge-Amp\`ere-type equation.


title: Cooling effect in emissions of 103mRh excited by bremsstrahlung

abstract:
  Nonlinear characteristic emissions of K alpha, K beta and gamma with a
significant triplet splitting at room temperature are observed from the
long-lived nuclear state of 103mRh excited by bremsstrahlung irradiation. A
pronounced phase-transition-like narrowing of the emission profiles occurs
immediately after the sample is cooled down to 77 K. The room temperature
profiles reappear again abruptly and almost reversibly as the temperature
drifts freely back to approximately the ice point after the filling of liquid
nitrogen is stopped. These emission properties at 300 K and at low temperature
may indicate that the 103mRh nuclei are in collective states.


title:
Explicit Constructions of the non-Abelian $\mathbf{p^3}$-Extensions Over
  $\mathbf{\QQ}$

abstract:
  Let $p$ be an odd prime. Let $F/k$ be a cyclic extension of degree $p$ and of
characteristic different from $p$. The explicit constructions of the
non-abelian $p^{3}$-extensions over $k$, are induced by certain elements in
${F(\mu_{p})}^{*}$. In this paper we let $k=\QQ$ and present sufficient
conditions for these elements to be suitable for the constructions. Polynomials
for the non-abelian groups of order 27 over $\QQ$ are constructed. We describe
explicit realizations of those groups with exactly two ramified primes, without
consider Scholz conditions.


title:
Lecture notes on "Combinatorial Criteria for Uniqueness of Gibbs
  Measures"

abstract:
  These notes are dedicated to whom may be interested in algorithms, Markov
chain, coupling, and graph theory etc. I present some preliminaries on coupling
and explanations of the important formulas or phrases, which may be helpful for
us to understand D. Weitz's paper "Combinatorial Criteria for Uniqueness of
Gibbs Measures" with ease.


title:
Direct and inverse scattering problems for spherical Electromagnetic
  waves in chiral media

abstract:
  We study the direct and inverse scattering problems when the incident
electromagnetic field is a time harmonic point- generated wave in a chiral
medium and the scatterer is a perfectly conducting sphere. The exact Green s
function and the electric far-field patterns of the scattering problem are
constructed. For a small sphere, a closed-form approximation of the scattered
wave field at the source of the incident spherical wave is obtained. These
near-field results lead to the solution of an inverse problem. We also treat
the same inverse problem using far-field results via the leading order term in
the low-frequency asymptotic expansion of the scattering cross-section.


title: Ramanujan sums analysis of long-period sequences and 1/f noise

abstract:
  Ramanujan sums are exponential sums with exponent defined over the
irreducible fractions. Until now, they have been used to provide converging
expansions to some arithmetical functions appearing in the context of number
theory. In this paper, we provide an application of Ramanujan sum expansions to
periodic, quasiperiodic and complex time series, as a vital alternative to the
Fourier transform. The Ramanujan-Fourier spectrum of the Dow Jones index over
13 years and of the coronal index of solar activity over 69 years are taken as
illustrative examples. Distinct long periods may be discriminated in place of
the 1/f^{\alpha} spectra of the Fourier transform.


title: Coexistence of triplet superconductivity and itinerant ferromagnetism

abstract:
  The triplet superconductivity in $UGe_2$ and $URhGe$ coexists with itinerant
ferromagnetism such that in the pressure-temperature phase diagram the whole
region occupied by the superconducting state is situated inside a more vast
ferromagnetic region. In the same family metal UCoGe the pressure dependent
critical lines T_{Curie}(P) and T_{sc}(P) of the ferromagnet and the
superconducting phase transitions intersect each other. The two-band
multidomain superconducting ferromagnet state arises at temperatures below both
of these lines. Here I describe the symmetry and the order parameters of the
paramagnet as well of the multidomain ferromagnet superconducting states. The
Josephson coupling between two adjacent ferromagnet superconducting domains is
discussed.


title:
A Note on Moduli Stabilisation in Heterotic Models in the Presence of
  Matter Fields

abstract:
  In this brief note we analyse a toy model which can be derived from heterotic
string compactifications on half-flat manifolds with SU(3) structure at first
order in \alpha' (ie including matter fields). We show that for this model,
finding solutions with viable gauge group poses the same problems as finding
solutions in the absence of matter fields.


title:
How the relation e^2/4pi = 1/137 may be obtained in the framework of
  Quantum Electrodynamics

abstract:
  In this pedagogical note it is demonstrated how the numeric value of fine
structure constant may be established by comparing results following from the
calculations in the framework of Quantum Electrodynamics with the experimental
data. As an observable, the coefficient of 1/r in the Coulomb law is used.


title: A discrete inhomogeneous model for the yeast cell cycle

abstract:
  We study the robustness and stability of the yeast cell regulatory network by
using a general inhomogeneous discrete model. We find that inhomogeneity, on
average, enhances the stability of the biggest attractor of the dynamics and
that the large size of the basin of attraction is robust against changes in the
parameters of inhomogeneity. We find that the most frequent orbit, which
represents the cell-cycle pathway, has a better biological meaning than the one
exhibited by the homogeneous model.


title:
Temperature-driven phase transitions in SrBi$_2$Ta$_2$O$_9$ from
  first-principles calculations

abstract:
  The phase transition sequence of SrBi$_2$Ta$_2$O$_9$ is investigated using a
shell model with parameters fitted to first-principles calculations. We show
that the complex interplay between polar and nonpolar instabilities leads to
the presence of two phase transitions, corroborating the existence of an
intermediate orthorhombic paraelectric phase. This phase is characterized by
the rotation of the TaO$_6$ octahedra around the a-axis. We show that this
phase can be also detected from the dielectric response of the material. The
present approach constitutes a powerful tool for a theoretical prediction of
intermediate phases, not yet observed experimentally, in other Aurivillius
compounds.


title: Diffractive physics in ALICE

abstract:
  The ALICE experiment at the LHC is presented and a diffractive double gap
trigger is described. Signatures of Pomeron and Odderon are discussed together
with photoproduction of heavy quarks as a possible signature of gluon
saturation.


title:
Entanglement evolution of a two-qubit system with decay beyond
  rotating-wave approximation

abstract:
  Two noninteracting atoms, initially entangled in Bell states, are coupled to
a one-mode cavity. Based on the reduced non-perturbative quantum master
equation, the entanglement evolution of the two atoms with decay is
investigated beyond rotating-wave approximation. It is shown that the
counter-rotating wave terms have great influence on the disentanglement
behavior. The phenomenon of entanglement sudden death and entanglement sudden
birth will occur.


title:
Undulation textures at the phase transitions of some alkyloxybenzoic
  acids

abstract:
  We observed undulated smectic textures for some compounds of the
4,n-alkyloxybenzoic (nOBAC) acid series, at transitions between the smectic and
the isotropic phase and between the smectic and nematic phase. Studied
compounds were 12OBAC, 16OBAC and a binary mixture of 12- and 16OBAC. The
undulations are dressing a usual Schlieren texture. In the case of the binary
mixture, an interesting fingerprint pattern is observed too.


title: A locally finite tree that behaves like an infinite star

abstract:
  We construct a tree T of maximal degree 3 with infinitely many leaves such
that whenever finitely many of them are removed, the remaining tree is
isomorphic to T. In this sense T resembles an infinite star.


title:
Exchange current contributions in null-plane quantum models of elastic
  electron deuteron scattering

abstract:
  We investigate exchange current contributions to elastic electron-deuteron
scattering using exactly Poincar\'e invariant quantum mechanics with a
null-plane kinematic symmetry. Our model exchange current is motivated by
one-pion-exchange physics. Exact current conservation and current covariance
are satisfied by using this current to compute a linearly independent set of
current matrix elements. The remaining current matrix elements are generated
from the independent matrix elements using the covariance and current
conservation constraints. The presence of the exchange current increases the
sensitivity to the choice of independent current matrix elements. Two choices
of independent matrix elements that have distinct motivations lead to a good
description of all of the elastic scattering observables for momentum transfers
below 8 (GeV)$^2$.


title:
Radial differential rotation vs surface differential rotation:
  investigation based on dynamo models

abstract:
  Differential rotation plays a crucial role in the alpha-omega dynamo, and
thus also in creation of magnetic fields in stars with convective outer
envelopes. Still, measuring the radial differential rotation on stars is
impossible with the current techniques, and even the measurement of surface
differential rotation is difficult. In this work we investigate the surface
differential rotation obtained from dynamo models using similar techniques as
are used on observations, and compare the results with the known radial
differential rotation used when creating the Dynamo model.


title: Reduced nonlinear description of Farley-Buneman instability

abstract:
  In the study on nonlinear wave-wave processes in an ionosphere and a
magnetosphere usually the main attention is paid to investigation of plasma
turbulence at well developed stage, when the wide spectrum of plasma wave is
present. On the other side, it is well known that even if the number of
cooperating waves remains small due to a competition of processes of their
instability and attenuation, the turbulence appears in the result of their
stochastic behavior. The regimes of nonlinear dynamics of low frequency waves
excited due to Farley-Buneman instability in weakly ionized and inhomogeneous
ionospheric plasma in the presence of electric current perpendicular to ambient
magnetic field are considered. The problem is essentially three dimensional and
difficult for full numerical simulation, but the strong collisional damping of
waves allow to assume that in this case a perturbed state of plasma can be
described as finite set of interacting waves, some of which are unstable and
other strongly damping. The proposed nonlinear model allow to make full study
of nonlinear stabilization, conditions of stochasticity and to consider the
different regimes and properties of few mode plasma turbulence.


title:
Decay widths of resonances and pion scattering lengths in a globally
  invariant linear sigma model with vector mesons

abstract:
  We calculate low-energy meson decay processes and pion-pion scattering
lengths in a two-flavour linear sigma model with global chiral symmetry,
exploring the scenario in which the scalar mesons $f_0$(600) and $a_0$(980) are
assumed to be $\bar q q$ states.


title: Protein-Interaction-Networks: More than mere modules

abstract:
  Cellular function is widely believed to be organized in a modular fashion. On
all scales and at all levels of complexity, relatively independent sub-units
perform relatively independent sub-tasks of biological function. This
functional modularity must be reflected in the topology of molecular networks.
But how a functional module should be represented in an interaction network is
an open question. In protein-interaction networks (PIN), one can identify a
protein-complex as a module on a small scale, i.e. modules are understood as
densely linked, resp. interacting, groups of proteins, that are only sparsely
interacting with the rest of the network.
  In this contribution, we show that extrapolating this concept of cohesively
linked clusters of proteins as modules to the scale of the entire PIN
inevitable misses important and functionally relevant structure inherent in the
network. As an alternative, we introduce a novel way of decomposing a network
into functional roles and show that this represents network structure and
function more efficiently. This finding should have a profound impact on all
module assisted methods of protein function prediction and should shed new
light on how functional modules can be represented in molecular interaction
networks in general.


title:
The scientific use and productivity of the Telescopio Nazionale Galileo
  (TNG)

abstract:
  This paper reviews the scientific use of the TNG from the beginning of
regular observations till the end of 2007. Statistics are given for the time
request, use and productivity of the telescope and its focal plane instruments.
Information on the down-times and a list of the major technical works/upgrades
are also included.


title:
Exploring the X-ray emission properties of the supernova remnant
  G67.7+1.8 and its central X-ray sources

abstract:
  We have studied the supernova remnant G67.7+1.8 with the Chandra X-ray
observatory. The remnant's X-ray morphology correlates well with the double-arc
structure seen at radio wavelength. The X-ray spectra of the northern and
southern rim of G67.7+1.8 exhibit emission line features of highly ionized
metals, which suggests that most of the observed X-rays originate in a thermal
plasma. We find magnesium, silicon, and sulphur are overabundant relative to
the solar values. Gaussian emission lines at $\sim4$ keV and $\sim7$ keV are
detected. The $\sim4$ keV line is consistent with K-emission lines from
$^{44}$Ca and/or $^{44}$Sc whereas the $\sim7$ keV line feature may arise from
unresolved Fe-K lines. Chandra's sub-arcsecond angular resolution allowed us to
detect four faint point sources located within $\sim1.5$ arc-minutes of the
geometrical remnant center. Among these objects, CXOU195424.75+312824.9 and
CXOU195429.82+312834.1 do not have optical counterparts, leaving them as
candidates for a possible compact stellar remnant.


title:
Star-forming cores embedded in a massive cold clump: Fragmentation,
  collapse and energetic outflows

abstract:
  The fate of massive cold clumps, their internal structure and collapse need
to be characterised to understand the initial conditions for the formation of
high-mass stars, stellar systems, and the origin of associations and clusters.
We explore the onset of star formation in the 75 M_sun SMM1 clump in the region
ISOSS J18364-0221 using infrared and (sub-)millimetre observations including
interferometry. This contracting clump has fragmented into two compact cores
SMM1 North and South of 0.05 pc radius, having masses of 15 and 10 M_sun, and
luminosities of 20 and 180 L_sun. SMM1 South harbours a source traced at 24 and
70um, drives an energetic molecular outflow, and appears supersonically
turbulent at the core centre. SMM1 North has no infrared counterparts and shows
lower levels of turbulence, but also drives an outflow. Both outflows appear
collimated and parsec-scale near-infrared features probably trace the
outflow-powering jets. We derived mass outflow rates of at least 4E-5 M_sun/yr
and outflow timescales of less than 1E4 yr. Our HCN(1-0) modelling for SMM1
South yielded an infall velocity of 0.14 km/s and an estimated mass infall rate
of 3E-5 M_sun/yr. Both cores may harbour seeds of intermediate- or high-mass
stars. We compare the derived core properties with recent simulations of
massive core collapse. They are consistent with the very early stages dominated
by accretion luminosity.


title: A local branching heuristic for MINLPs

abstract:
  Local branching is an improvement heuristic, developed within the context of
branch-and-bound algorithms for MILPs, which has proved to be very effective in
practice. For the binary case, it is based on defining a neighbourhood of the
current incumbent solution by allowing only a few binary variables to flip
their value, through the addition of a local branching constraint. The
neighbourhood is then explored with a branch-and-bound solver. We propose a
local branching scheme for (nonconvex) MINLPs which is based on iteratively
solving MILPs and NLPs. Preliminary computational experiments show that this
approach is able to improve the incumbent solution on the majority of the test
instances, requiring only a short CPU time. Moreover, we provide algorithmic
ideas for a primal heuristic whose purpose is to find a first feasible
solution, based on the same scheme.


title: Fresh look at the Hagedorn mass spectrum as seen in the experiments

abstract:
  The medium dependent finite width is introduced into an exactly solvable
model with the general mass-volume spectrum of the QGP bags. The model allows
us to estimate the minimal value of the QGP bags' width from the lattice QCD
data. The large width of the QGP bags not only explains the observed deficit in
the number of hadronic resonances comparing to the Hagedorn mass spectrum, but
also clarifies the reason why the heavy QGP bags cannot be directly observed as
metastable states in a hadronic phase.


title: Introduction to Electroweak Symmetry Breaking

abstract:
  In these lectures, I review the status of the electroweak sector of the
Standard Model, with an emphasis on the importance of radiative corrections and
searches for the Standard Model Higgs boson. A discussion of the special role
of the TeV energy scale in electroweak physics is included.


title: Dunkl Hyperbolic Equations

abstract:
  We introduce and study the Dunkl symmetric systems. We prove the
well-posedness results for the Cauchy problem for these systems. Eventually we
describe the finite speed of it. Next the semi-linear Dunkl-wave equations are
also studied.


title: The Virtually Cyclic Classifying Space of the Heisenberg Group

abstract:
  We are interested in the relationship between the virtual cohomological
dimension (or vcd) of a discrete group Gamma and the smallest possible
dimension of a model for the classifying space of Gamma relative to its family
of virtually cyclic subgroups. In this paper we construct a model for the
virtually cyclic classifying space of the Heisenberg group. This model has
dimension 3, which equals the vcd of the Heisenberg group. We also prove that
there exists no model of dimension less than 3.


title: The length of chains in algebraic lattices

abstract:
  We study how the existence in an algebraic lattice $L$ of a chain of a given
type is reflected in the join-semilattice $K(L)$ of its compact elements. We
show that for every chain $\alpha$ of size $\kappa$, there is a set $\B$ of at
most $2^{\kappa}$ join-semilattices, each one having a least element such that
an algebraic lattice $L$ contains no chain of order type $I(\alpha)$ if and
only if the join-semilattice $K(L)$ of its compact elements contains no
join-subsemilattice isomorphic to a member of $\B$. We show that among the
join-subsemilattices of $[\omega]^{<\omega}$ belonging to $\B$, one is
embeddable in all the others. We conjecture that if $\alpha$ is countable,
there is a finite set $\B$.


title:
The Observation of Formation and Annihilation of Solitons and Standing
  Strain Wave Superstructures in a Two-Dimensional Colloidal Crystal

abstract:
  Confining a colloidal crystal within a long narrow channel produced by two
parallel walls can be used to impose a meso-scale superstructure of a
predominantly mechanical elastic character [Chui et al., EPL 2008, 83, 58004].
When the crystal is compressed in the direction perpendicular to the walls, we
obtain a structural transition when the number of rows of particles parallel to
the walls decreases by one. All the particles of this vanishing row are
distributed throughout the crystal. If the confining walls are structured (say
with a corrugation along the length of the walls), then these extra particles
are distributed neither uniformly nor randomly; rather, defect structures are
created along the boundaries resembling "soliton staircases", inducing a
non-uniform strain pattern within the crystal. Here we study the conditions of
stability, formation and annihilation of these solitons using a coarse grained
description of the dynamics. The processes are shown by comparing superimposed
configurations as well as molecular animations obtained from our simulations.
Also the corresponding normal and shear stresses during the transformation are
calculated. A study of these dynamical processes should be useful for
controlling strain wave superstructures in the self-assembly of various nano-
and meso scaled particles.


title: Equivalence of SQL Queries in Presence of Embedded Dependencies

abstract:
  We consider the problem of finding equivalent minimal-size reformulations of
SQL queries in presence of embedded dependencies [1]. Our focus is on
select-project-join (SPJ) queries with equality comparisons, also known as safe
conjunctive (CQ) queries, possibly with grouping and aggregation. For SPJ
queries, the semantics of the SQL standard treat query answers as multisets
(a.k.a. bags), whereas the stored relations may be treated either as sets,
which is called bag-set semantics for query evaluation, or as bags, which is
called bag semantics. (Under set semantics, both query answers and stored
relations are treated as sets.)
  In the context of the above Query-Reformulation Problem, we develop a
comprehensive framework for equivalence of CQ queries under bag and bag-set
semantics in presence of embedded dependencies, and make a number of conceptual
and technical contributions. Specifically, we develop equivalence tests for CQ
queries in presence of arbitrary sets of embedded dependencies under bag and
bag-set semantics, under the condition that chase [9] under set semantics
(set-chase) on the inputs terminates. We also present equivalence tests for
aggregate CQ queries in presence of embedded dependencies. We use our
equivalence tests to develop sound and complete (whenever set-chase on the
inputs terminates) algorithms for solving instances of the Query-Reformulation
Problem with CQ queries under each of bag and bag-set semantics, as well as for
instances of the problem with aggregate queries.


title:
A Supersymmetric B-L Dark Matter Model and the Observed Anomalies in the
  Cosmic Rays

abstract:
  We propose a simple model of supersymmetric dark matter that can explain
recent results from PAMELA and ATIC experiments. It is based on a U(1)_B-L
extension of the minimal supersymmetric standard model. The dark matter
particle is a linear combination of the U(1)_B-L gaugino and Higgsino partners
of Higgs fields that break the B-L around one TeV. The dominant mode of dark
matter annihilation is to the lightest of the new Higgs fields, which has a
mass in the GeV range, and its subsequent decay mainly produces taus or muons
by the virtue of B-L charges. This light Higgs also results in Sommerfeld
enhancement of the dark matter annihilation cross section, which can be >~
10^3. For a dark matter mass in the 1-2 TeV range, the model provides a good
fit to the PAMELA data and a reasonable fit to the ATIC data. We also briefly
discuss the prospects of this model for direct detection experiments and the
LHC.


title:
First principles perspective on the microscopic model for Cs2CuCl4 and
  Cs2CuBr4

abstract:
  We investigate the microscopic model for the frustrated layered
antiferromagnets Cs2CuCl4 and Cs2CuBr4 by performing ab initio density
functional theory (DFT) calculations and with the help of the tight-binding
method. The combination of both methods provide the relevant interaction paths
in these materials, and we estimate the corresponding exchange constants. We
find for Cs2CuCl4 that the calculated ratio of the strongest in-plane exchange
constants J'/J between the spin-1/2 Cu ions agrees well with neutron scattering
experiments. The microscopic model based on the derived exchange constants is
tested by comparing the magnetic susceptibilities obtained from exact
diagonalization with experimental data. The electronic structure differences
between Cs2CuCl4 and Cs2CuBr4 are also analyzed.


title:
Infrared Emission by Dust Around lambda Bootis Stars: Debris Disks or
  Thermally Emitting Nebulae?

abstract:
  We present a model that describes stellar infrared excesses due to heating of
the interstellar (IS) dust by a hot star passing through a diffuse IS cloud.
This model is applied to six lambda Bootis stars with infrared excesses.
Plausible values for the IS medium (ISM) density and relative velocity between
the cloud and the star yield fits to the excess emission. This result is
consistent with the diffusion/accretion hypothesis that lambda Bootis stars (A-
to F-type stars with large underabundances of Fe-peak elements) owe their
characteristics to interactions with the ISM. This proposal invokes radiation
pressure from the star to repel the IS dust and excavate a paraboloidal dust
cavity in the IS cloud, while the metal-poor gas is accreted onto the stellar
photosphere. However, the measurements of the infrared excesses can also be fit
by planetary debris disk models. A more detailed consideration of the
conditions to produce lambda Bootis characteristics indicates that the majority
of infrared-excess stars within the Local Bubble probably have debris disks.
Nevertheless, more distant stars may often have excesses due to heating of
interstellar material such as in our model.


title: Slavnov-Taylor Identities in Coulomb Gauge Yang-Mills Theory

abstract:
  Two aspects of the color charge in Coulomb gauge continuum Yang-Mills theory
are discussed. The first aspect is the existence of a conserved and vanishing
total charge exhibited within the first order functional formalism. The second
aspect is the closure of the set of Slavnov-Taylor identities in the second
order functional formalism, such that the exact solution for temporal Green's
functions is in principle possible and thereby preserving the color charge.


title:
Lattice cutoff effects for F_Ds with improved Wilson fermions - a final
  lesson from the quenched case

abstract:
  In view of the recent excitement about a tension between determinations of
f_Ds from experiment and from simulations of lattice QCD with dynamical quarks,
we try to clear up the picture of lattice determinations in the continuum limit
of the quenched approximation. For O(a) improved Wilson quarks we see linear
scaling in the squared lattice spacing a^2 only for a<~0.08fm. For coarser
lattices we observe significant contaminations from higher order cutoff
effects. As an aside we also study the scaling of the charm quark mass and the
ratio of the vector to the pseudo-scalar decay constant and the spin-splitting.


title:
Local Convergence of the Proximal Point Method for a Special Class of
  Nonconvex Functions on Hadamard Manifolds

abstract:
  Local convergence analysis of the proximal point method for special class of
nonconvex function on Hadamard manifold is presented in this paper. The well
definedness of the sequence generated by the proximal point method is
guaranteed. Moreover, is proved that each cluster point of this sequence
satisfies the necessary optimality conditions and, under additional
assumptions, its convergence for a minimizer is obtained.


title: Greedy Signal Recovery Review

abstract:
  The two major approaches to sparse recovery are L1-minimization and greedy
methods. Recently, Needell and Vershynin developed Regularized Orthogonal
Matching Pursuit (ROMP) that has bridged the gap between these two approaches.
ROMP is the first stable greedy algorithm providing uniform guarantees.
  Even more recently, Needell and Tropp developed the stable greedy algorithm
Compressive Sampling Matching Pursuit (CoSaMP). CoSaMP provides uniform
guarantees and improves upon the stability bounds and RIC requirements of ROMP.
CoSaMP offers rigorous bounds on computational cost and storage. In many cases,
the running time is just O(NlogN), where N is the ambient dimension of the
signal. This review summarizes these major advances.


title: eta/s is critical (at phase transitions)

abstract:
  The viscosity over entropy density ratio, or KSS number, can help isolate the
critical point in the hadron phase-diagram in Relativistic Heavy Ion
Collisions. We argue that this quantity does have a minimum at a phase
transition or crossover. Although indications from conventional
non-relativistic gases point out to even a divergence in eta/s when the
phase-transition is first-order, since the critical exponent is rather low,
this will be more difficult to ascertain in RHIC or FAIR. The experimental data
are more likely to reveal a discontinuity for a first order phase transition or
a smooth minimum at a crossover.


title: A Poincar\'e invariant treatment of the three-nucleon problem

abstract:
  I summarize recent progress in the treatment of the Poincar\'e three-nucleon
problem at intermediate energies