title: Semi-classical approach for Anosov diffeomorphisms and Ruelle resonances

abstract:
  In this paper, we show that some spectral properties of Anosov
diffeomorphisms can be obtained by semi-classical analysis. In particular the
Ruelle resonances which are eigenvalues of the Ruelle transfer operator acting
in suitable anisotropic Sobolev spaces and which govern the decay of dynamical
correlations, can be treated as the quantum resonances of open quantum systems
in the Aguilar-Baslev-Combes theory or the more recent Helffer-Sjostrand
phase-space theory.


title:
New Solutions for the Planetary Dynamics in HD160691 using a Newtonian
  Model and Latest Data

abstract:
  In this letter we present several new three and four-planet solutions based
on the most current available radial velocity data for HD160691 ($\mu$Ara).
These solutions are optimised using the Planetary Orbit Fitting Process (POFP)
which is programmed and executed in MATLAB. POFP is based on a full integration
of the system's multiple-body Newtonian equations of motion and on a multi
level optimisation utilizing a variety of algorithms. The POFP solutions are
presented in the context of the Keplerian-based solutions already appearing in
the literature which we have reproduced here for comparison. The different
solutions and their properties are compared over all data sets separately and
combined. The new solutions do not seem to exhibit instabilities and are both
co-planar and three-dimensional. We also provide a comparative prediction of
the published and new solutions showing their diversion in the near future. In
the short term, this projection will allow to choose between the variety of
solutions as further observations are made.


title: SPB stars in the open SMC cluster NGC 371

abstract:
  Pulsation in beta Cep and SPB stars are driven by the kappa mechanism which
depends critically on the metallicity. It has therefore been suggested that
beta Cep and SPB stars should be rare in the Magellanic Clouds which have lower
metallicities than the solar neighborhood. To test this prediction we have
observed the open SMC cluster NGC 371 for 12 nights in order to search for beta
Cep and SPB stars. Surprisingly, we find 29 short-period B-type variables in
the upper part of the main sequence, many of which are probably SPB stars. This
result indicates that pulsation is still driven by the kappa mechanism even in
low metallicity environments. All the identified variables have periods longer
than the fundamental radial period which means that they cannot be beta Cep
stars. Within an amplitude detection limit of 5 mmag no stars in the top of the
HR-diagram show variability with periods shorter than the fundamental radial
period. So if beta Cep stars are present in the cluster they oscillate with
amplitudes below 5 mmag, which is significantly lower than the mean amplitude
of beta Cep stars in the Galaxy. We see evidence that multimode pulsation is
more common in the upper part of the main sequence than in the lower. We have
also identified 5 eclipsing binaries and 3 periodic pulsating Be stars in the
cluster field.


title: On Spectral Triples in Quantum Gravity I

abstract:
  This paper establishes a link between Noncommutative Geometry and canonical
quantum gravity. A semi-finite spectral triple over a space of connections is
presented. The triple involves an algebra of holonomy loops and a Dirac type
operator which resembles a global functional derivation operator. The
interaction between the Dirac operator and the algebra reproduces the Poisson
structure of General Relativity. Moreover, the associated Hilbert space
corresponds, up to a discrete symmetry group, to the Hilbert space of
diffeomorphism invariant states known from Loop Quantum Gravity.
Correspondingly, the square of the Dirac operator has, in terms of canonical
quantum gravity, the form of a global area-squared operator. Furthermore, the
spectral action resembles a partition function of Quantum Gravity. The
construction is background independent and is based on an inductive system of
triangulations. This paper is the first of two papers on the subject.


title: On Spectral Triples in Quantum Gravity II

abstract:
  A semifinite spectral triple for an algebra canonically associated to
canonical quantum gravity is constructed. The algebra is generated by based
loops in a triangulation and its barycentric subdivisions. The underlying space
can be seen as a gauge fixing of the unconstrained state space of Loop Quantum
Gravity. This paper is the second of two papers on the subject.


title:
Near ML detection using Dijkstra's algorithm with bounded list size over
  MIMO channels

abstract:
  We propose Dijkstra's algorithm with bounded list size after QR decomposition
for decreasing the computational complexity of near maximum-likelihood (ML)
detection of signals over multiple-input-multiple-output (MIMO) channels. After
that, we compare the performances of proposed algorithm, QR decomposition
M-algorithm (QRD-MLD), and its improvement. When the list size is set to
achieve the almost same symbol error rate (SER) as the QRD-MLD, the proposed
algorithm has smaller average computational complexity.


title:
The Fundamental Plane of QSOs and the Relationship Between Host and
  Nucleus

abstract:
  We present results from an archival study of 70 medium-redshift QSOs observed
with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. The
QSOs have magnitudes M_V <= -23 (total nuclear plus host light) and redshifts
$0.06 <= z <= 0.46$. The aim of the present study is to investigate the
connections between the nuclear and host properties of QSOs, using
high-resolution images and removing the central point source to reveal the host
structure. We confirm that more luminous QSO nuclei are found in more luminous
host galaxies. Using central black hole masses from the literature, we find
that nuclear luminosity also generally increases with black hole mass, but it
is not tightly correlated. Nuclear luminosities range from 2.3% to 200% of the
Eddington limit. Those in elliptical hosts cover the range fairly evenly, while
those in spirals are clustered near the Eddington limit. Using a principal
components analysis, we find a kind of fundamental plane relating the nuclear
luminosity to the size and effective surface magnitude of the bulge. Using
optical nuclear luminosity, this relationship explains 96.1% of the variance in
the overall sample, while another version of the relationship uses x-ray
nuclear luminosity and explains 95.2% of the variance. The form of this QSO
fundamental plane shows similarities to the well-studied fundamental plane of
elliptical galaxies, and we examine the possible relationship between them as
well as the difficulties involved in establishing this connection.


title:
Negative Longitudinal Magneto-Thermoelectric Power in a Semiconductor
  Parabolic Quantum Well

abstract:
  We present a theoretical study of the electronic thermoelectric power of a
semiconductor parabolic quantum well in a magnetic field. The case of a
longitudinal magnetic field, with respect to the temperature gradient, has been
considered. The calculations were carried out taking into account
spin-splitting of the dimensionally quantized electronic energy levels. It has
been shown that in the region of strong confinement the thermoelectric power
decreases with increasing magnetic field, which is related to the downward
shift of the lower Zeeman-split spin subband.


title:
Large N expansion of convergent matrix integrals, holomorphic anomalies,
  and background independence

abstract:
  We propose an asymptotic expansion formula for matrix integrals, including
oscillatory terms (derivatives of theta-functions) to all orders. This formula
is heuristically derived from the analogy between matrix integrals, and formal
matrix models (combinatorics of discrete surfaces), after summing over filling
fractions. The whole oscillatory series can also be resummed into a single
theta function. We also remark that the coefficients of the theta derivatives,
are the same as those which appear in holomorphic anomaly equations in string
theory, i.e. they are related to degeneracies of Riemann surfaces. Moreover,
the expansion presented here, happens to be independent of the choice of a
background filling fraction.


title: The Spectral Sequence of Blazars - Status and Perspectives

abstract:
  The present status of the blazar spectral sequence is discussed, including
new findings about blazars selected with different criteria than the original
complete radio-samples. Despite extensive searches of blazars "breaking" the
sequence, the original idea proposed 10 years ago, still seems to hold. On the
other hand the forthcoming launch of the GLAST satellite will provide a new
selection band for blazars and blazar related populations as well as fantastic
progress on the spectra and variability behaviour of presently known blazars.
The order of magnitude increase in sensitivity of GLAST will allow to detect
gamma-rays from jets with lower power and/or lower beaming factor, thus
sampling a much wider population.


title: SAT Has No Wizards

abstract:
  An (encoded) decision problem is a pair (E, F) where E=words that encode
instances of the problem, F=words to be accepted. We use "strings" in a
technical sense. With an NP problem (E, F) we associate the "logogram" of F
relative to E, which conveys structural information on E, F, and how F is
embedded in E. The kernel Ker(P) of a program P that solves (E, F) consists of
those strings in the logogram that are used by P. There are relations between
Ker(P) and the complexity of P. We develop an application to SAT that relies
upon a property of internal independence of SAT. We show that SAT cannot have
in its logogram strings serving as collective certificates. As consequence, all
programs that solve SAT have same kernel.


title:
Several New Active Galactic Nuclei Among X-ray Sources Detected by
  INTEGRAL and SWIFT Observatories

abstract:
  We present the results of the optical identifications of a set of X-ray
sources from the all-sky surveys of INTEGRAL and SWIFT observatories. Optical
data were obtained with Russian-Turkish 1.5-m Telescope (RTT150). Nine X-ray
sources were identified as active galactic nuclei (AGNs). Two of them are
hosted by nearby, nearly exactly edge-on, spiral galaxies MCG -01-05-047 and
NGC 973. One source, IGR J16562-3301, is most probably BL Lac object (blazar).
Other AGNs are observed as stellar-like nuclei of spiral galaxies, with broad
emission lines in their spectra.
  For the majority of our hard X-ray selected AGNs, their hard X-ray
luminosities are well-correlated with the luminosities in [OIII],5007 optical
emission line. However, the luminosities of some AGNs deviate from this
correlation. The fraction of these objects can be as high as 20%. In
particular, the flux in [OIII] line turns to be lower in two nearby edge-on
spiral galaxies, which can be explained by the extinction in their galactic
disks.


title:
Searching for Extra Z' from Strings and Other Models at the LHC with
  Leptoproduction

abstract:
  Discovery potentials for extra neutral interactions at the Large Hadron
Collider in forthcoming experiments are analyzed using resonant
leptoproduction. For this purpose we use high precision next-to-next-to-leading
order (NNLO) determinations of the QCD background in this channel, at the tail
of the Drell-Yan distributions, in the invariant mass region around $ 0.8< Q <
2.5 $ TeV. We focus our analysis primarily on a novel string-inspired
$Z^\prime$, obtained in left-right symmetric free fermionic heterotic string
models and whose existence at low energies is motivated by its role in
suppressing proton decay mediation. We analyze the parametric dependence of the
predictions and perform comparison with other models based on bottom up
approaches, that are constructed by requiring anomaly cancellation and enlarged
Higgs structure. We show that the results are not particularly sensitive to the
specific charge assignments. This may render quite difficult the extraction of
significant information from the forward-backward asymmetries on the resonance,
assuming that these are possible due to a sizeable width. The challenge to
discover extra (non anomalous) $Z^\prime$ in this kinematic region remains
strongly dependent on the size of the new gauge coupling. Weakly coupled extra
$Z^\prime$ will not be easy to identify even with a very good theoretical
determination of the QCD background through NNLO.


title: Van Der Waals Revisited

abstract:
  The van-der-Waals version of the second virial coefficient is not far from
being exact if the model parameters are appropriately chosen. It is shown how
the van-der-Waals resemblance originates from the interplay of thermal
averaging and superposition of scattering phase shift contributions. The
derivation of the two parameters from the quantum virial coefficient reveals a
fermion-boson symmetry in non-ideal quantum gases. Numerical details are worked
out for the Helium quantum gases.


title: Metastability of hadronic compact stars

abstract:
  Pure hadronic compact stars, above a threshold value of their gravitational
mass (central pressure), are metastable to the conversion to quark stars
(hybrid or strange stars). In this paper, we present a systematic study of the
metastability of pure hadronic compact stars using different relativistic
models for the equation of state (EoS). In particular, we compare results for
the quark-meson coupling (QMC) model with those for the Glendenning--Moszkowski
parametrization of the non-linear Walecka model (NLWM). For QMC model, we find
large values ($M_{cr} = 1.6$ -- $1.9 M_\odot$) for the critical mass of the
hadronic star sequence and we find that the formation of a quark star is only
possible with a soft quark matter EoS. For the Glendenning--Moszkowski
parametrization of the NLWM, we explore the effect of different hyperon
couplings on the critical mass and on the stellar conversion energy. We find
that increasing the value of the hyperon coupling constants shifts the bulk
transition point for quark deconfinement to higher densities, increases the
stellar metastability threshold mass and the value of the critical mass, and
thus makes the formation of quark stars less likely. For the largest values of
the hyperon couplings we find a critical mass which may be as high as 1.9 - 2.1
$M_\odot$. These stellar configurations, which contain a large central hyperon
fraction ($f_{Y,cr} \sim 30 %$), would be able to describe highly-massive
compact stars, such as the one associated to the millisecond pulsars PSR
B1516+02B with a mass $M = 1.94^{+ 0.17}_{- 0.19} M_{\odot}$.


title: Monopole condensation in two-flavour Adjoint QCD

abstract:
  In QCD with adjoint fermions (aQCD) the deconfining transition takes place at
a lower temperature than the chiral transition. We study the two transitions by
use of the Polyakov Loop, the monopole order parameter and the chiral
condensate. The deconfining transition is first order, the chiral is a
crossover. The order parameters for confinement are not affected by the chiral
transition. We conclude that the degrees of freedom relevant to confinement are
different from those describing chiral symmetry.


title: Geometric structure of class two nilpotent groups and subgroup growth

abstract:
  In this paper we derive an explicit expression for the normal zeta function
of class two nilpotent groups whose associated Pfaffian hypersurface is smooth.
In particular, we show how the local zeta function depends on counting mod p
rational points on related varieties, and we describe the varieties that can
appear in such a decomposition. As a corollary, we also establish explicit
results on the degree of polynomial subgroup growth in these groups, and we
study the behaviour of poles of this zeta function. Under certain geometric
conditions, we also confirm that these functions satisfy a functional equation.


title:
Monte Carlo simulation of joint density of states in one-dimensional
  Lebwohl-Lasher model using Wang-Landau algorithm

abstract:
  Monte Carlo simulation using the Wang-Landau algorithm has been performed in
an one-dimensional Lebwohl-Lasher model. Both one-dimensional and
two-dimensional random walks have been carried out. The results are compared
with the exact results which are available for this model.


title: Emergent gravity and Dark Energy

abstract:
  This is an invited contribution to be included in a multi-authored book on
"Dark Energy", to be edited by Pilar Ruiz-Lapuente and published by Cambridge
University Press.


title:
The supersymmetric solutions and extensions of ungauged matter-coupled
  N=1,d=4 supergravity

abstract:
  We find the most general supersymmetric solutions of ungauged N=1,d=4
supergravity coupled to an arbitrary number of vector and chiral
supermultiplets, which turn out to be essentially pp-waves and strings. We also
introduce magnetic 1-forms and their supersymmetry transformations and 2-forms
associated to the isometries of the scalar manifold and their supersymmetry
transformations. Only the latter can couple to BPS objects (strings), in
agreement with our results.


title: Groebner deformations, connectedness and cohomological dimension

abstract:
  This paper is an outcome of the author's master thesis written under the
supervision of Aldo Conca. We prove some results relating connectedness
properties with (local) cohomological dimension. As an interesting corollary we
have that every initial complex of a Cohen-Macaulay ideal is strongly
connected.


title:
Magnetoresistance behavior of a ferromagnetic shape memory alloy:
  Ni_1.75Mn_1.25Ga

abstract:
  A negative-positive-negative switching behavior of magnetoresistance (MR)
with temperature is observed in a ferromagnetic shape memory alloy
Ni_1.75Mn_1.25Ga. In the austenitic phase between 300 and 120 K, MR is negative
due to s-d scattering. Curiously, below 120K MR is positive, while at still
lower temperatures in the martensitic phase, MR is negative again. The positive
MR cannot be explained by Lorentz contribution and is related to a magnetic
transition. Evidence for this is obtained from ab initio density functional
theory, a decrease in magnetization and resistivity upturn at 120 K. Theory
shows that a ferrimagnetic state with anti-ferromagnetic alignment between the
local magnetic moments of the Mn atoms is the energetically favoured ground
state. In the martensitic phase, there are two competing factors that govern
the MR behavior: a dominant negative trend up to the saturation field due to
the decrease of electron scattering at twin and domain boundaries; and a weaker
positive trend due to the ferrimagnetic nature of the magnetic state. MR
exhibits a hysteresis between heating and cooling that is related to the first
order nature of the martensitic phase transition.


title:
Gluon density and $F_{2}$ functions from BK equation with impact
  parameter dependence

abstract:
  In this note we fix the preliminary results obtained in the study of gluon
density function of the paper \cite{bom3}. The LO BK equation for unintegrated
gluon density with impact parameter dependence is considered in order to fix
the parameters of the proposed model. In particular the form of initial
condition for the equations of proton-proton scattering from \cite{bom3} is
determined, which is similar to the form of fenomenological GBW ansatz. The
gluon density function and $F_{2}$ function are also calculated and compared
with the results for the gluon density and $F_{2}$ functions from the GRV
parameterization for different values of $Q^2$. It is shown, that the results
for $F_2$ structure function of the considered model are in the good accordance
with the results obtained from the GRV parameterization of parton densities.


title: Pair Formation in a t-J Model

abstract:
  We have investigated the formation of bound state of two electrons in
different kind of lattices using a t-J-U model.


title: The semiflow of a reaction diffusion equation with a singular potential

abstract:
  We study the semiflow $\mathcal{S}(t)$ defined by a semilinear parabolic
equation with a singular square potential $V(x)=\frac{\mu}{|x|^2}$. It is known
that the Hardy-Poincar\'{e} inequality and its improved versions, have a
prominent role on the definition of the natural phase space. Our study concerns
the case $0<\mu\leq\mu^*$, where $\mu^*$ is the optimal constant for the
Hardy-Poincar\'{e} inequality. On a bounded domain of $\mathbb{R}^N$, we
justify the global bifurcation of nontrivial equilibrium solutions for a
reaction term $f(s)=\lambda s-|s|^{2\gamma}s$, with $\lambda$ as a bifurcation
parameter. The global bifurcation result is used to show that any solution
$\phi(t)=\mathcal{S}(t)\phi_0$, initiating form initial data $\phi_0\geq 0$
($\phi_0\leq 0$), $\phi_0\not\equiv 0$, tends to the unique nonnegative
(nonpositive) equilibrium.


title: Lectures on the Routh-Hurwitz problem

abstract:
  The notes contain a streamlined account on stability of univariate
polynomials and related problems


title: Relativistic description of heavy tetraquarks

abstract:
  The masses of the ground state and excited heavy tetraquarks with hidden
charm and bottom are calculated within the relativistic diquark-antidiquark
picture. The dynamics of the light quark in a heavy-light diquark is treated
completely relativistically. The diquark structure is taken into account by
calculating the diquark-gluon form factor. New experimental data on
charmonium-like states above the open charm threshold are discussed. The
obtained results indicate that X(3872), Y(4260), Y(4360), Z(4433) and Y(4660)
can be tetraquark states with hidden charm.


title: An Algebra Containing the Two-Sided Convolution Operators

abstract:
  We present an intrinsically defined algebra of operators containing the right
and left invariant Calder\'on-Zygmund operators on a stratified group. The
operators in our algebra are pseudolocal and bounded on L^p (1<p<\infty). This
algebra provides an example of an algebra of singular integrals that falls
outside of the classical Calder\'on-Zygmund theory.


title:
Simulations of Baryon Acoustic Oscillations I: Growth of Large-Scale
  Density Fluctuations

abstract:
  We critically examine how well the evolution of large-scale density
perturbations is followed in cosmological $N$-body simulations. We first run a
large volume simulation and perform a mode-by-mode analysis in
three-dimensional Fourier space. We show that the growth of large-scale
fluctuations significantly deviates from linear theory predictions. The
deviations are caused by {\it nonlinear} coupling with a small number of modes
at largest scales owing to finiteness of the simulation volume. We then develop
an analytic model based on second-order perturbation theory to quantify the
effect. Our model accurately reproduces the simulation results. For a single
realization, the second-order effect appears typically as ``zig-zag'' patterns
around the linear-theory prediction, which imprints artificial ``oscillations''
that lie on the real baryon-acoustic oscillations. Although an ensemble average
of a number of realizations approaches the linear theory prediction, the
dispersions of the realizations remain large even for a large simulation volume
of several hundred megaparsecs on a side. For the standard $\Lambda$CDM model,
the deviations from linear growth rate are as large as 10 percent for a
simulation volume with $L = 500h^{-1}$Mpc and for a bin width in wavenumber of
$\Delta k = 0.005h$Mpc$^{-1}$, which are comparable to the intrinsic variance
of Gaussian random realizations. We find that the dispersions scales as
$\propto L^{-3/2} \Delta k^{-1/2}$ and that the mean dispersion amplitude can
be made smaller than a percent only if we use a very large volume of $L >
2h^{-1}$Gpc. The finite box size effect needs to be appropriately taken into
account when interpreting results from large-scale structure simulations for
future dark energy surveys using baryon acoustic oscillations.


title:
Modern Infinitesimal Analysis Applied to the Physical Metric dS and a
  Theoretical Verification of a Time-dilation Conjecture

abstract:
  In this paper, the modern theory of infinitesimals is applied to the General
Relativity metric dS and its geometric and physical meanings are rigorously
investigated. Employing results obtained via the time-dependent Schrodinger
equation, gravitational time-dilation expressions are obtained and are shown to
be caused by gravitationally altered photon interactions with atomic
structures.


title:
Structure and evolution of super-Earth to super-Jupiter exoplanets: I.
  heavy element enrichment in the interior

abstract:
  We examine the uncertainties in current planetary models and we quantify
their impact on the planet cooling histories and mass-radius relationships.
These uncertainties include (i) the differences between the various equations
of state used to characterize the heavy material thermodynamical properties,
(ii) the distribution of heavy elements within planetary interiors, (iii) their
chemical composition and (iv) their thermal contribution to the planet
evolution. Our models, which include a gaseous H/He envelope, are compared with
models of solid, gasless Earth-like planets in order to examine the impact of a
gaseous envelope on the cooling and the resulting radius. We find that for a
fraction of heavy material larger than 20% of the planet mass, the distribution
of the heavy elements in the planet's interior affects substantially the
evolution and thus the radius at a given age. For planets with large core mass
fractions ($\simgr$ 50%), such as the Neptune-mass transiting planet GJ436b,
the contribution of the gravitational and thermal energy from the core to the
planet cooling history is not negligible, yielding a $\sim$ 10% effect on the
radius after 1 Gyr. We show that the present mass and radius determinations of
the massive planet Hat-P-2b require at least 200 $\mearth$ of heavy material in
the interior, at the edge of what is currently predicted by the core-accretion
model for planet formation. We show that if planets as massive as $\sim$ 25
$\mjup$ can form, as predicted by improved core-accretion models, deuterium is
able to burn in the H/He layers above the core, even for core masses as large
as $\sim$ 100 $\mearth$. We provide extensive grids of planetary evolution
models from 10 $\mearth$ to 10 M$_{\rm Jup}$, with various fractions of heavy
elements.


title: Entanglement Enhances Security in Secret Sharing

abstract:
  We analyze tolerable quantum bit error rates in secret sharing protocols, and
show that using entangled encoding states is advantageous in the case when the
eavesdropping attacks are local. We also provide a criterion for security in
secret sharing -- a parallel of the Csiszar-Korner criterion in single-receiver
cryptography.


title:
Conditions for stability and instability of retrial queueing systems
  with general retrial times

abstract:
  We study the stability of single server retrial queues under general
distribution for retrial times and stationary ergodic service times, for three
main retrial policies studied in the literature: classical linear, constant and
control policies. The approach used is the renovating events approach to obtain
sufficient stability conditions by strong coupling convergence of the process
modeling the dynamics of the system to a unique stationary ergodic regime. We
also obtain instability conditions by convergence in distribution to improper
limiting sequences.


title: Taub-NUT Black Holes in Third order Lovelock Gravity

abstract:
  We consider the existence of Taub-NUT solutions in third order Lovelock
gravity with cosmological constant, and obtain the general form of these
solutions in eight dimensions. We find that, as in the case of Gauss-Bonnet
gravity and in contrast with the Taub-NUT solutions of Einstein gravity, the
metric function depends on the specific form of the base factors on which one
constructs the circle fibration. Thus, one may say that the independence of the
NUT solutions on the geometry of the base space is not a robust feature of all
generally covariant theories of gravity and is peculiar to Einstein gravity. We
find that when Einstein gravity admits non-extremal NUT solutions with no
curvature singularity at $r=N$, then there exists a non-extremal NUT solution
in third order Lovelock gravity. In 8-dimensional spacetime, this happens when
the metric of the base space is chosen to be $\Bbb{CP}^{3}$. Indeed, third
order Lovelock gravity does not admit non-extreme NUT solutions with any other
base space. This is another property which is peculiar to Einstein gravity. We
also find that the third order Lovelock gravity admits extremal NUT solution
when the base space is $T^{2}\times T^{2}\times T^{2}$ or $S^{2}\times
T^{2}\times T^{2}$. We have extended these observations to two conjectures
about the existence of NUT solutions in Lovelock gravity in any
even-dimensional spacetime.


title:
Direct observation of domain wall structures in curved permalloy wires
  containing an anti-notch

abstract:
  The formation and field response of head-to-head domain walls in curved
permalloy wires, fabricated to contain a single anti-notch, have been
investigated using Lorentz microscopy. High spatial resolution maps of the
vector induction distribution in domain walls close to the anti-notch have been
derived and compared with micromagnetic simulations. In wires of 10 nm
thickness the walls are typically of a modified asymmetric transverse wall
type. Their response to applied fields tangential to the wire at the anti-notch
location was studied. The way the wall structure changes depends on whether the
field moves the wall away from or further into the notch. Higher fields are
needed and much more distorted wall structures are observed in the latter case,
indicating that the anti-notch acts as an energy barrier for the domain wall.


title: A Construction for Constant-Composition Codes

abstract:
  By employing the residue polynomials, a construction of constant-composition
codes is given. This construction generalizes the one proposed by Xing[16]. It
turns out that when d=3 this construction gives a lower bound of
constant-composition codes improving the one in [10]. Moreover, for d>3, we
give a lower bound on maximal size of constant-composition codes. In
particular, our bound for d=5 gives the best possible size of
constant-composition codes up to magnitude.


title:
A note on quantum algorithms and the minimal degree of epsilon-error
  polynomials for symmetric functions

abstract:
  The degrees of polynomials representing or approximating Boolean functions
are a prominent tool in various branches of complexity theory. Sherstov
recently characterized the minimal degree deg_{\eps}(f) among all polynomials
(over the reals) that approximate a symmetric function f:{0,1}^n-->{0,1} up to
worst-case error \eps: deg_{\eps}(f) = ~\Theta(deg_{1/3}(f) +
\sqrt{n\log(1/\eps)}). In this note we show how a tighter version (without the
log-factors hidden in the ~\Theta-notation), can be derived quite easily using
the close connection between polynomials and quantum algorithms.


title:
Comments to the review "Nonthermal phenomena in clusters of galaxies" by
  Y.Rephaeli et al. that will appear on the book: Clusters of galaxies: beyond
  the thermal view

abstract:
  Comments to the review "Nonthermal Phenomena in Clusters of Galaxies" by
Y.Rephaeli et al. (arXiv:0801.0982 [astro-ph]) that regard the presence of a
hard X-ray excess in the Coma cluster, A2199, A2163 and the Bullet cluster.


title: Bi-Hamiltonian nature of the equation $u_{tx}=u_{xy} u_y-u_{yy} u_x$

abstract:
  We study non-linear integrable partial differential equations naturally
arising as bi-Hamiltonian Euler equations related to the looped cotangent
Virasoro algebra. This infinite-dimensional Lie algebra (constructed in
\cite{OR}) is a generalization of the classical Virasoro algebra to the case of
two space variables. Two main examples of integrable equations we obtain are
quite well known. We show that the relation between these two equations is
similar to that between the Korteweg-de Vries and Camassa-Holm equations.


title:
Generation of Multiple Circular Walls on a Thin Film of Nematic Liquid
  Crystal by Laser Scanning

abstract:
  We found that multiple circular walls (MCW) can be generated on a thin film
of a nematic liquid crystal through a spiral scanning of a focused IR laser.
The ratios between radii of adjacent rings of MCW were almost constant. These
constant ratios can be explained theoretically by minimization of the Frank
elastic free energy of nematic medium. The director field on a MCW exhibits
chiral symmetry-breaking although the elastic free energies of both chiral MCWs
are degenerated, i.e., the director on a MCW can rotate clockwise or
counterclockwise along the radial direction.


title:
An empirical investigation of the g-index for 26 physicists in
  comparison with the h-index, the A-index, and the R-index

abstract:
  Hirsch has introduced the h-index to quantify an individual's scientific
research output by the largest number h of a scientist's papers that received
at least h citations. In order to take into account the highly skewed frequency
distribution of citations, Egghe proposed the g-index as an improvement of the
h-index. I have worked out 26 practical cases of physicists from the Institute
of Physics at Chemnitz University of Technology and compare the h and g values.
It is demonstrated that the g-index discriminates better between different
citation patterns. This can also be achieved by evaluating Jin's A-index which
reflects the average number of citations in the h-core and interpreting it in
conjunction with the h-index. h and A can be combined into the R-index to
measure the h-core's citation intensity. I have also determined the A and R
values for the 26 data sets. For a better comparison, I utilize interpolated
indices. The correlations between the various indices as well as with the total
number of papers and the highest citation counts are discussed. The largest
Pearson correlation coefficient is found between g and R. Although the
correlation between g and h is relatively strong, the arrangement of the data
set is significantly different, depending on whether they are put into order
according to the values of either h or g.


title: Spontaneous symmetry breaking of gap solitons in double-well traps

abstract:
  We introduce a two dimensional model for the Bose-Einstein condensate with
both attractive and repulsive nonlinearities. We assume a combination of a
double well potential in one direction, and an optical lattice along the
perpendicular coordinate. We look for dual core solitons in this model,
focusing on their symmetry-breaking bifurcations. The analysis employs a
variational approximation, which is verified by numerical results. The
bifurcation which transforms antisymmetric gap solitons into asymmetric ones is
of supercritical type in the case of repulsion; in the attraction model,
increase of the optical latttice strength leads to a gradual transition from
subcritical bifurcation (for symmetric solitons) to a supercritical one.


title:
Natural Lie Algebra bundles on rank two s-K\"ahler manifolds, abelian
  varieties and moduli of curves

abstract:
  We prove that one can obtain natural bundles of Lie algebras on rank two
s-K\"ahler manifolds, whose fibres are isomorphic to so(s+1,s+1), su(s+1,s+1)
and sl(2s + 2,\R). In the most rigid case (which includes complex tori and
abelian varieties) these bundles have natural flat connections, whose flat
global sections act naturally on cohomology. We also present several natural
examples of manifolds which can be equipped with an s-K\"ahler structure with
various levels of rigidity: complex tori and abelian varieties, cotangent
bundles of smooth manifolds and moduli of pointed elliptic curves.


title:
Moment Explosions and Long-Term Behavior of Affine Stochastic Volatility
  Models

abstract:
  We consider a class of asset pricing models, where the risk-neutral joint
process of log-price and its stochastic variance is an affine process in the
sense of Duffie, Filipovic and Schachermayer [2003]. First we obtain conditions
for the price process to be conservative and a martingale. Then we present some
results on the long-term behavior of the model, including an expression for the
invariant distribution of the stochastic variance process. We study moment
explosions of the price process, and provide explicit expressions for the time
at which a moment of given order becomes infinite. We discuss applications of
these results, in particular to the asymptotics of the implied volatility
smile, and conclude with some calculations for the Heston model, a model of
Bates and the Barndorff-Nielsen-Shephard model.


title:
Turbulent Compressible Convection with Rotation - Penetration above a
  Convection Zone

abstract:
  We perform Large eddy simulations of turbulent compressible convection in
stellar-type convection zones by solving the Navi\'{e}r-Stokes equations in
three dimensions. We estimate the extent of penetration into the stable layer
above a stellar-type convection zone by varying the rotation rate
({\boldmath$\rm\Omega$}), the inclination of the rotation vector ($\theta$) and
the relative stability ($S$) of the upper stable layer. The computational
domain is a rectangular box in an f-plane configuration and is divided into two
regions of unstable and stable stratification with the stable layer placed
above the convectively unstable layer. Several models have been computed and
the penetration distance into the stable layer above the convection zone is
estimated by determining the position where time averaged kinetic energy flux
has the first zero in the upper stable layer. The vertical grid spacing in all
the model is non-uniform, and is less in the upper region so that the flows are
better resolved in the region of interest. We find that the penetration
distance increases as the rotation rate increases for the case when the
rotation vector is aligned with the vertical axis. However, with the increase
in the stability of the upper stable layer, the upward penetration distance
decreases. Since we are not able to afford computations with finer resolution
for all the models, we compute a number of models to see the effect of
increased resolution on the upward penetration. In addition, we estimate the
upper limit on the upward convective penetration from stellar convective cores.


title: Sudden Birth Versus Sudden Death of Entanglement in Multipartite Systems

abstract:
  We study the entanglement dynamics of two cavities interacting with
independent reservoirs. Expectedly, we observe that, as the cavity entanglement
is depleted, it is transferred to the reservoir degrees of freedom. We find
that when the cavity entanglement suddenly disappear, the reservoir
entanglement suddenly and necessarily appears. Surprisingly, we show that this
{\it entanglement sudden birth} can manifest before, simultaneously, or even
after {\it entanglement sudden death}. Finally, we present an explanatory study
of other entanglement partitions and of higher dimensional systems.


title: On the Kert\'esz line: Some rigorous bounds

abstract:
  We study the Kert\'esz line of the $q$--state Potts model at (inverse)
temperature $\beta$, in presence of an external magnetic field $h$. This line
separates two regions of the phase diagram according to the existence or not of
an infinite cluster in the Fortuin-Kasteleyn representation of the model. It is
known that the Kert\'esz line $h_K (\beta)$ coincides with the line of first
order phase transition for small fields when $q$ is large enough. Here we prove
that the first order phase transition implies a jump in the density of the
infinite cluster, hence the Kert\'esz line remains below the line of first
order phase transition. We also analyze the region of large fields and prove,
using techniques of stochastic comparisons, that $h_K (\beta)$ equals $\log (q
- 1) - \log (\beta - \beta_p)$ to the leading order, as $\beta$ goes to
$\beta_p = - \log (1 - p_c)$ where $p_c$ is the threshold for bond percolation.

categories: cond-mat.stat-mech math-ph math.MP math.PR


title:
Energy scales of Lu(1-x)Yb(x)Rh2Si2 by means of thermopower
  investigations

abstract:
  We present the thermopower S(T) and the resistivity rho(T) of
Lu(1-x)Yb(x)Rh2Si2 in the temperature range 3 K < T < 300 K. S(T) is found to
change from two minima for dilute systems (x < 0.5) to a single large minimum
in pure YbRh2Si2. A similar behavior has also been found for the magnetic
contribution to the resistivity rho_mag(T). The appearance of the low-T extrema
in S(T) and rho_mag(T) is attributed to the lowering of the Kondo scale with
decreasing x. The evolution of the characteristic energy scales for both the
Kondo effect and the crystal electric field splitting are deduced. An
extrapolation allows to estimate the Kondo temperature of YbRh2Si2 to 29 K.


title:
Weak-coupling Treatment of Electronic (Anti-)Ferroelectricity in the
  Extended Falicov-Kimball Model

abstract:
  We study the (spinless) Falicov-Kimball model extended by a finite band width
(hopping $t_f$) of the localized (f-) electrons in infinite dimensions in the
weak-coupling limit of a small local interband Coulomb correlation $U$ for half
filling. In the case of overlapping conduction- and f-bands different kinds of
ordered solutions are possible, namely charge-density wave (CDW) order,
electronic ferroelectricity (EFE) and electronic antiferroelectricity (EAFE).
The order parameters are calculated as a function of the model parameters and
of the temperature. There is a first-order phase transition from the CDW-phase
to the EFE- or EAFE-phase. The total energy is calculated to determine the
thermodynamically stable solution. The quantum phase diagrams are calculated.


title:
A review of the Statistical Mechanics approach to Random Optimization
  Problems

abstract:
  We review the connection between statistical mechanics and the analysis of
random optimization problems, with particular emphasis on the random k-SAT
problem. We discuss and characterize the different phase transitions that are
met in these problems, starting from basic concepts. We also discuss how
statistical mechanics methods can be used to investigate the behavior of local
search and decimation based algorithms.


title:
The sigma -> gamma gamma Width from Nucleon Electromagnetic
  Polarizabilities

abstract:
  The lightest QCD resonance, the sigma, has been recently fixed in the pi-pi
scattering amplitude.
  The nature of this state remains nowadays one of the most intriguing and
difficult issues in particle physics. Its coupling to photons is crucial to
discriminate its structure. We propose a new method that fixes this coupling
using only available precise experimental data on the proton electromagnetic
polarizabilities together with analyticity and unitarity. Taking into account
the uncertainties in the analysis and in the parameter values, our result is
Gamma_{pole}(sigma -> gamma gamma) = (1.2 +- 0.4) KeV.


title:
The Longstaff--Schwartz algorithm for L\'{e}vy models: Results on fast
  and slow convergence

abstract:
  We investigate the Longstaff--Schwartz algorithm for American option pricing
assuming that both the number of regressors and the number of Monte Carlo paths
tend to infinity. Our main results concern extensions, respectively,
applications of results by Glasserman and Yu [Ann. Appl. Probab. 14 (2004)
2090--2119] and Stentoft [Manag. Sci. 50 (2004) 1193--1203] to several L\'{e}vy
models, in particular the geometric Meixner model. A convenient setting to
analyze this convergence problem is provided by the L\'{e}vy--Sheffer systems
introduced by Schoutens and Teugels.


title: Numerical determination of the material properties of porous dust cakes

abstract:
  The formation of planetesimals requires the growth of dust particles through
collisions. Micron-sized particles must grow by many orders of magnitude in
mass. In order to understand and model the processes during this growth, the
mechanical properties, and the interaction cross sections of aggregates with
surrounding gas must be well understood. Recent advances in experimental
(laboratory) studies now provide the background for pushing numerical aggregate
models onto a new level. We present the calibration of a previously tested
model of aggregate dynamics. We use plastic deformation of surface asperities
as the physical model to bring critical velocities for sticking into accordance
with experimental results. The modified code is then used to compute
compression strength and the velocity of sound in the aggregate at different
densities. We compare these predictions with experimental results and conclude
that the new code is capable of studying the properties of small aggregates.


title: Differential Geometry of Gerbes and Differential Forms

abstract:
  We discuss certain aspects of the combinatorial approach to the differential
geometry of non-abelian gerbes, due to W. Messing and the author
(arXiv:math.AG/0106083), and give a more direct derivation of the associated
cocycle equations. This leads us to a more restrictive definition of the
corresponding coboundary relations. We also show that the diagrammatic proofs
of certain local curving and curvature equations may be replaced by
computations with differential forms.


title:
Chiral perturbation theory study of the axial $N\to\Delta(1232)$
  transition

abstract:
  We have performed a theoretical study of the axial Nucleon to Delta(1232)
($N\to\Delta$) transition form factors up to one-loop order in covariant baryon
chiral perturbation theory within a formalism in which the unphysical spin-1/2
components of the $\Delta$ fields are decoupled.


title:
A Conclusive Experimentation Evidences that Mental States Follow Quantum
  Mechanics. Further Experimentation Indicates that in Mind States Bell
  Inequality Violation is Possible

abstract:
  In the first part of the paper we reach an experimental final confirmation
that mental states follow quantum mechanics. In the second part further
experimentation indicates that in mind states Bell inequality violation is
possible.


title:
Identifying the rotation rate and the presence of dynamic weather on
  extrasolar Earth-like planets from photometric observations

abstract:
  With the recent discoveries of hundreds of extrasolar planets, the search for
planets like Earth and life in the universe, is quickly gaining momentum. In
the future, large space observatories could directly detect the light scattered
from rocky planets, but they would not be able to spatially resolve a planet's
surface. Using reflectance models and real cloud data from satellite
observations, here we show that, despite Earth's dynamic weather patterns, the
light scattered by the Earth to a hypothetical distant observer as a function
of time contains sufficient information to accurately measure Earth's rotation
period. This is because ocean currents and continents result in relatively
stable averaged global cloud patterns. The accuracy of these measurements will
vary with the viewing geometry and other observational constraints. If the
rotation period can be measured with accuracy, data spanning several months
could be coherently combined to obtain spectroscopic information about
individual regions of the planetary surface. Moreover, deviations from a
periodic signal can be used to infer the presence of relatively short-live
structures in its atmosphere (i.e., clouds). This could provide a useful
technique for recognizing exoplanets that have active weather systems, changing
on a timescale comparable to their rotation. Such variability is likely to be
related to the atmospheric temperature and pressure being near a phase
transition and could support the possibility of liquid water on the planet's
surface.


title: An Inhomogeneous Transference Principle and Diophantine Approximation

abstract:
  In a landmark paper, D.Y. Kleinbock and G.A. Margulis established the
fundamental Baker-Sprindzuk conjecture on homogeneous Diophantine approximation
on manifolds. Subsequently, there has been dramatic progress in this area of
research. However, the techniques developed to date do not seem to be
applicable to inhomogeneous approximation. Consequently, the theory of
inhomogeneous Diophantine approximation on manifolds remains essentially
non-existent.
  In this paper we develop an approach that enables us to transfer homogeneous
statements to inhomogeneous ones. This is rather surprising as the
inhomogeneous theory contains the homogeneous theory and so is more general. As
a consequence, we establish the inhomogeneous analogue of the Baker-Sprindzuk
conjecture. Furthermore, we prove a complete inhomogeneous version of the
profound theorem of Kleinbock, Lindenstrauss & Weiss on the extremality of
friendly measures. The results obtained in this paper constitute the first step
towards developing a coherent inhomogeneous theory for manifolds in line with
the homogeneous theory.


title:
The VIMOS VLT Deep Survey: Testing the gravitational instability
  paradigm at z ~ 1

abstract:
  We have reconstructed the three-dimensional density fluctuation maps to z ~
1.5 using the distribution of galaxies observed in the VVDS-Deep survey. We use
this overdensity field to measure the evolution of the probability distribution
function and its lower-order moments over the redshift interval 0.7<z<1.5. We
apply a self-consistent reconstruction scheme which includes a complete
non-linear description of galaxy biasing and which has been throughly tested on
realistic mock samples. We find that the variance and skewness of the galaxy
distribution evolve over this redshift interval in a way that is remarkably
consistent with predictions of first- and second-order perturbation theory.
This finding confirms the standard gravitational instability paradigm over
nearly 9 Gyrs of cosmic time and demonstrates the importance of accounting for
the non-linear component of galaxy biasing to consistently reproduce the
higher-order moments of the galaxy distribution and their evolution.


title: Experimental evidence of non-Gaussian fluctuations near a critical point

abstract:
  The orientation fluctuations of the director of a liquid crystal are
measured, by a sensitive polarization interferometer, close to the
Fr\'eedericksz transition, which is a second order transition driven by an
electric field. We show that near the critical value of the field the spatially
averaged order parameter has a generalized Gumbel distribution instead of a
Gaussian one. The latter is recovered away from the critical point. The
relevance of slow modes is pointed out. The parameter of generalized Gumbel is
related to the effective number of degrees of freedom.


title: Size limiting in Tsallis statistics

abstract:
  Power law scaling is observed in many physical, biological and
socio-economical complex systems and is now considered as an important property
of these systems. In general, power law exists in the central part of the
distribution. It has deviations from power law for very small and very large
step sizes. Tsallis, through non-extensive thermodynamics, explained power law
distribution in many cases including deviation from the power law, both for
small and very large steps. In case of very large steps, they used heuristic
crossover approach. In real systems, the size is limited and thus, the size
limiting factor is important. In the present work, we present an alternative
model in which we consider that the entropy factor q decreases with step size
due to the softening of long range interactions or memory. This explains the
deviation of power law for very large step sizes. Finally, we apply this model
for distribution of citation index of scientists and examination scores and are
able to explain the entire distribution including deviations from power law.


title: Infrared Single-Photon Detector based on Silicon Two-Photon Absorption

abstract:
  We propose a scheme for infrared single-photon detection based on two-photon
absorption at room-temperature in Si avalanche photodiodes, where the detected
photon's energy is lower than the bandgap and the energy difference is
complemented by a pump field. A quantum non-perturbative model is developed for
non-degenerate two-photon absorption in direct and indirect semiconductors
yielding proper non-divergent rates allowing device efficiency optimization.
The proposed monolithic detector is simple, miniature, integrable and does not
require phase matching, while not compromising the performance and exhibiting
even better efficiency than the competing up-conversion schemes (~1 order of
magnitude) for similar optical pump levels.


title:
Back-action evasion and squeezing of a mechanical resonator using a
  cavity detector

abstract:
  We study the quantum measurement of a cantilever using a
parametrically-coupled electromagnetic cavity which is driven at the two
sidebands corresponding to the mechanical motion. This scheme, originally due
to Braginsky et al. [V. Braginsky, Y. I. Vorontsov, and K. P. Thorne, Science
209, 547 (1980)], allows a back-action free measurement of one quadrature of
the cantilever's motion, and hence the possibility of generating a squeezed
state. We present a complete quantum theory of this system, and derive simple
conditions on when the quantum limit on the added noise can be surpassed. We
also study the conditional dynamics of the measurement, and discuss how such a
scheme (when coupled with feedback) can be used to generate and detect squeezed
states of the oscillator. Our results are relevant to experiments in
optomechanics, and to experiments in quantum electromechanics employing
stripline resonators coupled to mechanical resonators.


title: Strain bursts in plastically deforming Molybdenum micro- and nanopillars

abstract:
  Plastic deformation of micron and sub-micron scale specimens is characterized
by intermittent sequences of large strain bursts (dislocation avalanches) which
are separated by regions of near-elastic loading. In the present investigation
we perform a statistical characterization of strain bursts observed in
stress-controlled compressive deformation of monocrystalline Molybdenum
micropillars. We characterize the bursts in terms of the associated elongation
increments and peak deformation rates, and demonstrate that these quantities
follow power-law distributions that do not depend on specimen orientation or
stress rate. We also investigate the statistics of stress increments in between
the bursts, which are found to be Weibull distributed and exhibit a
characteristic size effect. We discuss our findings in view of observations of
deformation bursts in other materials, such as face-centered cubic and
hexagonal metals.


title:
On the Schrodinger equation in $R^N$ under the effect of a general
  nonlinear term

abstract:
  In this paper we prove the existence of a positive solution to the equation
$-\Delta u + V(x)u=g(u)$ in $R^N,$ assuming the general hypotheses on the
nonlinearity introduced by Berestycki & Lions. Moreover we show that a
minimizing problem, related to the existence of a ground state, has no
solution.


title:
Dynamical simulation of bound antiproton-nuclear systems and observable
  signals of cold nuclear compression

abstract:
  On the basis of the kinetic equation with selfconsistent relativistic mean
fields acting on baryons and antibaryons, we study dynamical response of the
nucleus to an antiproton implanted in its interior. By solving numerically the
time-dependent Vlasov equation, we show that the compressed state is formed on
a rather short time scale of about 4-10 fm/c. This justifies the assumption,
that the antiproton annihilation may happen in the compressed nuclear
environment. The evolution of the nucleus after antiproton annihilation is
described by the same kinetic equation including collision terms. We show, that
nucleon kinetic energy spectra and the total invariant mass distributions of
produced mesons are quite sensitive observables to the antiproton annihilation
in the compressed nucleus.


title: NGC1600 - Cluster or Field Elliptical?

abstract:
  A study of the galaxy distribution in the field of the elliptical galaxy
NGC1600 has been undertaken. Although this galaxy is often classified as a
member of a loose group, all the neighbouring galaxies are much fainter and
could be taken as satellites of NGC1600. The number density profile of galaxies
in the field of this galaxy shows a decline with radius, with evidence of a
background at approximately 1.3 Mpc. The density and number density profile are
consistent with that found for other isolated early-type galaxies. NGC1600
appears as an extended source in X-rays, and the center of the X-ray emission
seems not to coincide with the center of the galaxy. The velocity distribution
of neighbouring galaxies has been measured from optical spectroscopic
observations and shows that the mean radial velocity is approximately 85 km/s
less than that of NGC1600, indicating that the centre of mass could lie outside
the galaxy. The velocity dispersion of the `group' is estimated at 429 km/s.
The inferred mass of the system is therefore of the order of 10^14 solar
masses, a value that corresponds to a large group. NGC1600 therefore shares
some similarities, but is not identical to, the `fossil clusters' detected in
X-ray surveys. Implications of this result for studies of isolated early-type
galaxies are briefly discussed.


title:
The chemical evolution of a Milky Way-like galaxy: the importance of a
  cosmologically motivated infall law

abstract:
  We aim at finding a cosmologically motivated infall law to understand if the
LambdaCDM cosmology can reproduce the main chemical characteristics of a Milky
Way-like spiral galaxy. In this work we test several different gas infall laws,
starting from that suggested in the two-infall model for the chemical evolution
of the Milky Way by Chiappini et al., but focusing on laws derived from
cosmological simulations which follows a concordance LambdaCDM cosmology. By
means of a detailed chemical evolution model for the solar vicinity, we study
the effects of the different gas infall laws on the abundance patterns and the
G-dwarf metallicity distribution. The cosmological gas infall law predicts two
main gas accretion episodes. By means of this cosmologically motivated infall
law, we study the star formation rate, the SNIa and SNII rate, the total amount
of gas and stars in the solar neighbourhood and the behaviour of several
chemical abundances. We find that the results of the two-infall model are fully
compatible with the evolution of the Milky Way with cosmological accretion
laws. A gas assembly history derived from a DM halo, compatible with the
formation of a late-type galaxy from the morphological point of view, can
produce chemical properties in agreement with the available observations.


title:
Fabrication of One-Dimensional Programmable-Height Nanostructures via
  Dynamic Stencil Deposition

abstract:
  Dynamic stencil deposition (DSD) techniques offer a variety of fabrication
advantages not possible with traditional lithographic processing, such as the
the ability to directly deposit nanostructures with programmable height
profiles. However, DSD systems have not enjoyed widespread usage due to their
complexity. We demonstrate a simple, low-profile, portable, one-dimensional
nanotranslation system that facilitates access to nanoscale DSD abilities.
Furthermore we show a variety of fabricated programmable-height nanostructures,
including parallel arrays of such structures, and suggest other applications
that exploit the unique capabilities of DSD fabrication methods.


title: QCD prediction for the non-$D\bar D$ annihilation decay of $\psi(3770)$

abstract:
  To clarify the marked difference between BES and CLEO measurements on the
non-$D\bar D$ decays of the $\psi(3770)$, a $1^{3}D_{1}$-dominated charmonium,
we calculate the annihilation decay of $\psi(3770)$ in NRQCD. By introducing
the color-octet contributions, the results are free from infrared divergences.
The color-octet matrix elements are estimated by solving the evolution
equations. The S-D mixing effect is found to be very small. With
$m_{c}=1.5\pm0.1\textrm{GeV}$ our result is $\Gamma(\psi(3770)\to \textrm{light
hadrons})=467^{-187}_{+338}\textrm{KeV}$. For $m_c=1.4$ GeV, together with the
observed hadronic transitions and E1 transitions, the non-$D\bar D$ decay
branching ratio of $\psi(3770)$ could reach about 5%. Our results do not favor
either of the results of BES and CLEO collaborations, and further experimental
tests are urged.


title:
On Miura Transformations and Volterra-Type Equations Associated with the
  Adler-Bobenko-Suris Equations

abstract:
  We construct Miura transformations mapping the scalar spectral problems of
the integrable lattice equations belonging to the Adler-Bobenko-Suris (ABS)
list into the discrete Schr\"odinger spectral problem associated with
Volterra-type equations. We show that the ABS equations correspond to
B\"acklund transformations for some particular cases of the discrete
Krichever-Novikov equation found by Yamilov (YdKN equation). This enables us to
construct new generalized symmetries for the ABS equations. The same can be
said about the generalizations of the ABS equations introduced by Tongas,
Tsoubelis and Xenitidis. All of them generate B\"acklund transformations for
the YdKN equation. The higher order generalized symmetries we construct in the
present paper confirm their integrability.


title: Multiple solutions of steady MHD flow of dilatant fluids

abstract:
  In this paper we consider the problem of a steady MHD flow of a non-Newtonian
power-law and electrically conducting fluid in presence of an applied magnetic
field. The boundary layer equations are solved in similarity form via the
Lyapunov energy method, we show that this problem has an infinite number of
positive global solutions.


title: Knudsen Diffusion in Silicon Nanochannels

abstract:
  Measurements on helium and argon gas flow through an array of parallel,
linear channels of 12 nm diameter and 200 micrometer length in a single
crystalline silicon membrane reveal a Knudsen diffusion type transport from
10^2 to 10^7 in Knudsen number Kn. The classic scaling prediction for the
transport diffusion coefficient on temperature and mass of diffusing
species,D_He ~ sqrt(T), is confirmed over a T range from 40 K to 300 K for He
and for the ratio of D_He/D_Ar ~ sqrt(m_Ar/m_He). Deviations of the channels
from a cylindrical form, resolved with transmission electron microscopy down to
subnanometer scales, quantitatively account for a reduced diffusivity as
compared to Knudsen diffusion in ideal tubular channels. The membrane
permeation experiments are described over 10 orders of magnitude in Kn,
encompassing the transition flow regime, by the unified flow model of Beskok
and Karniadakis.

categories: physics.flu-dyn cond-mat.mtrl-sci cond-mat.stat-mech nlin.SI physics.chem-ph


title: Algebra in superextensions of groups, I: zeros and commutativity

abstract:
  Given a group $X$ we study the algebraic structure of its superextension
  $\lambda(X)$. This is a right-topological semigroup consisting of all maximal
linked systems on $X$ endowed with the operation $$\mathcal A\circ\mathcal
B=\{C\subset X:\{x\in X:x^{-1}C\in\mathcal B\}\in\mathcal A\}$$ that extends
the group operation of $X$. We characterize right zeros of $\lambda(X)$ as
invariant maximal linked systems on $X$ and prove that $\lambda(X)$ has a right
zero if and only if each element of $X$ has odd order. On the other hand, the
semigroup $\lambda(X)$ contains a left zero if and only if it contains a zero
if and only if $X$ has odd order $|X|\le5$. The semigroup $\lambda(X)$ is
commutative if and only if $|X|\le4$. We finish the paper with a complete
description of the algebraic structure of the semigroups $\lambda(X)$ for all
groups $X$ of cardinality $|X|\le5$.


title: Yet More Ado About Nothing: The Remarkable Relativistic Vacuum State

abstract:
  An overview is given of what mathematical physics can currently say about the
vacuum state for relativistic quantum field theories on Minkowski space. Along
with a review of classical results such as the Reeh--Schlieder Theorem and its
immediate and controversial consequences, more recent results are discussed.
These include the nature of vacuum correlations and the degree of entanglement
of the vacuum, as well as the striking fact that the modular objects determined
by the vacuum state and algebras of observables localized in certain regions of
Minkowski space encode a remarkable range of physical information, from the
dynamics and scattering behavior of the theory to the external symmetries and
even the space--time itself. These modular objects also provide an intrinsic
characterization of the vacuum state itself, a fact which is of particular
relevance to the search for criteria to select physically significant reference
states for quantum field theories on curved space--times.


title: Three Parton Corrections in $B\to PP$ decays

abstract:
  The $1/m_b$ corrections from the three parton $q\bar{q}g$ Fock state of the
final state light meson in $B\to PP$ decays are evaluated by means of a
collinear expansion method. The impacts of these corrections on the $CP$
averaged branching ratios of the $B\to \pi K$ decays are analyzed.


title: Algebra in superextension of groups, II: cancelativity and centers

abstract:
  Given a countable group $X$ we study the algebraic structure of its
superextension $\lambda(X)$. This is a right-topological semigroup consisting
of all maximal linked systems on $X$ endowed with the operation $$\mathcal
A\circ\mathcal B=\{C\subset X:\{x\in X:x^{-1}C\in\mathcal B\}\in\mathcal A\}$$
that extends the group operation of $X$. We show that the subsemigroup
$\lambda^\circ(X)$ of free maximal linked systems contains an open dense subset
of right cancelable elements. Also we prove that the topological center of
$\lambda(X)$ coincides with the subsemigroup $\lambda^\bullet(X)$ of all
maximal linked systems with finite support. This result is applied to show that
the algebraic center of $\lambda(X)$ coincides with the algebraic center of $X$
provided $X$ is countably infinite. On the other hand, for finite groups $X$ of
order $3\le|X|\le5$ the algebraic center of $\lambda(X)$ is strictly larger
than the algebraic center of $X$.


title:
Radiation from early black holes - I: effects on the neutral
  inter-galactic medium

abstract:
  In the pre-reionization Universe, the regions of the inter-galactic medium
(IGM) which are far from luminous sources are the last to undergo reionization.
Until then, they should be scarcely affected by stellar radiation; instead, the
X-ray emission from an early black hole (BH) population can have much larger
influence. We investigate the effects of such emission, looking at a number of
BH model populations (differing for the cosmological density evolution of BHs,
the BH properties, and the spectral energy distribution of the BH emission). We
find that BH radiation can easily heat the IGM to 10^3-10^4 K, while achieving
partial ionization. The most interesting consequence of this heating is that
BHs are expected to induce a 21-cm signal (delta T_b ~ 20-30 mK at z<~12) which
should be observable with forthcoming experiments (e.g. LOFAR). We also find
that at z<~10 BH emission strongly increases the critical mass separating
star-forming and non-star-forming halos.


title: A Search for Excited Neutrinos in e-p Collisions at HERA

abstract:
  A search for excited neutrinos is performed using the full $e^{-}p$ data
sample collected by the H1 experiment at HERA at a centre-of-mass energy of 319
GeV, corresponding to a total luminosity of 184 pb$^{-1}$.The electroweak
decays of excited neutrinos ${\nu}^{*}{\to}{\nu}{\gamma}$,
${\nu}^{*}{\to}{\nu}Z$ and ${\nu}^{*}{\to}eW$ with subsequent hadronic or
leptonic decays of the $W$ and $Z$ bosons are considered. No evidence for
excited neutrino production is found. Mass dependent exclusion limits on
$\nu^*$ production cross sections and on the ratio of the coupling to the
compositeness scale $f/{\Lambda}$ are derived within gauge mediated models. A
limit on $f/{\Lambda}$, independent of the relative couplings to the SU(2) and
U(1) gauge bosons, is also determined. These limits extend the excluded region
to higher masses than has been possible in previous excited neutrino searches.


title: Right-topological semigroup operations on inclusion hyperspaces

abstract:
  We show that for any discrete semigroup $X$ the semigroup operation can be
extended to a right-topological semigroup operation on the space $G(X)$ of
inclusion hyperspaces on $X$. We detect some important subsemigroups of $G(X)$,
study the minimal ideal, the (topological) center, left cancelable elements of
$G(X)$, and describe the structure of the semigroups $G(\IZ_n)$ for small
numbers $n$.


title:
A sharp estimate and change on the dimension of the attractor for
  Allen-Cahn equations

abstract:
  We consider the semilinear reaction diffusion equation
$\partial_t\phi-\nu\Delta\phi-V(x)\phi+f(\phi)=0$, $\nu>0$ in a bounded domain
$\Omega\subset\mathbb{R}^N$. We assume the standard Allen-Cahn-type
nonlinearity, while the potential $V$ is either the inverse square potential
$V(x)=\delta |x|^{-2}$ or the borderline potential $V(x)=\delta
\mathrm{dist}(x,\partial\Omega)^{-2}$, $\delta\geq 0$ (thus including the
classical Allen-Cahn equation as a special case when $\delta=0$). In the
subcritical cases $\delta=0$, $N\geq 1$ and $0<\mu:=\frac{\delta}{\nu}<\mu^*$,
$N\geq 3$ (where $\mu^*$ is the optimal constant of Hardy and Hardy-type
inequalities), we present a new estimate on the dimension of the global
attractor. This estimate comes out by an improved lower bound for sums of
eigenvalues of the Laplacian by A. D. Melas (Proc. Amer. Math. Soc.
\textbf{131} (2003), 631-636). The estimate is sharp, revealing the existence
of (an explicitly given) threshold value for the ratio of the volume to the
moment of inertia of $\Omega$ on which the dimension of the attractor may
considerably change. Consideration is also given on the finite dimensionality
of the global attractor in the critical case $\mu=\mu^*$.


title: Finite temperature behaviour of the ISS-uplifted KKLT model

abstract:
  We study the static phase structure of the ISS-KKLT model for moduli
stabilisation and uplifting to a zero cosmological constant. Since the
supersymmetry breaking sector and the moduli sector are only gravitationally
coupled, we expect negligible quantum effects of the modulus upon the ISS
sector, and the other way around. Under this assumption, we show that the ISS
fields end up in the metastable vacua. The reason is not only that it is
thermally favoured (second order phase transition) compared to the phase
transition towards the supersymmetric vacua, but rather that the metastable
vacua form before the supersymmetric ones. This nice feature is exclusively due
to the presence of the KKLT sector. We also show that supergravity effects are
negligible around the origin of the field space. Finally, we turn to the
modulus sector and show that there is no destabilisation effect coming from the
ISS sector.


title: Lectures on instantons

abstract:
  This is a self-contained set of lecture notes on instantons in (super)
Yang-Mills theory in four dimensions and in quantum mechanics. First the basics
are derived from scratch: the regular and singular one-instanton solutions for
Yang-Mills theories with gauge groups SU(2) and SU(N), their bosonic and
fermionic zero modes, the path integral instanton measure, and supersymmetric
Yang-Mills theories in Euclidean space. Then we discuss applications: the
\theta-angle of QCD, the solution of the U(1) problem, the way Higgs fields
solve the large-instanton problem, and tunneling and phase transitions in
quantum mechanics and in nonabelian gauge theories. These lecture notes are an
extension of a review on Yang-Mills and D-instantons written in 2000 by both
authors and A.Belitsky


title:
Near-Infrared Imaging Polarimetry of Young Stellar Objects in
  rho-Ophiuchi

abstract:
  The results of a near-infrared (J H K LP) imaging linear polarimetry survey
of 20 young stellar objects (YSOs) in rho Ophiuchi are presented. The majority
of the sources are unresolved, with K-band polarizations, P_K < 6 per cent.
Several objects are associated with extended reflection nebulae. These objects
have centrosymmetric vector patterns with polarization discs over their cores;
maximum polarizations of P_K > 20 per cent are seen over their envelopes.
Correlations are observed between the degree of core polarization and the
evolutionary status inferred from the spectral energy distribution. K-band core
polarizations >6 per cent are only observed in Class I YSOs. A 3D Monte Carlo
model with oblate grains aligned with a magnetic field is used to investigate
the flux distributions and polarization structures of three of the rho Oph YSOs
with extended nebulae. A rho proportional to r^(-1.5) power law for the density
is applied throughout the envelopes. The large-scale centrosymmetric
polarization structures are due to scattering. However, the polarization
structure in the bright core of the nebula appears to require dichroic
extinction by aligned non-spherical dust grains. The position angle indicates a
toroidal magnetic field in the inner part of the envelope. Since the measured
polarizations attributed to dichroic extinction are usually <10 per cent, the
grains must either be nearly spherical or very weakly aligned. The higher
polarizations observed in the outer parts of the reflection nebulae require
that the dust grains responsible for scattering have maximum grain sizes <=1.05
microns.


title:
The Regulation of Cooling and Star Formation in Luminous Galaxies by AGN
  Feedback and the Cooling-Time/Entropy Threshold for the Onset of Star
  Formation

abstract:
  Using broadband optical imaging and Chandra X-ray data for a sample of 46
cluster central dominant galaxies (CDGs), we investigate the connection between
star formation, the intracluster medium (ICM), and the central active galactic
nucleus (AGN). We report the discovery of a remarkably sharp threshold for the
onset of star formation that occurs when the central cooling time of the hot
atmosphere falls below ~ 5x10^8 yr, or equivalently when the central entropy
falls below ~ 30 keV cm^2. In addition to this criterion, star formation in
cooling flows also appears to require that the X-ray and galaxy centroids lie
within ~ 20 kpc of each other, and that the jet (cavity) power is smaller than
the X-ray cooling luminosity. These three criteria, together with the high
ratio of cooling time to AGN outburst (cavity) age across our sample, directly
link the presence of star formation and AGN activity in CDGs to cooling
instabilities in the intracluster plasma. Our results provide compelling
evidence that AGN feedback into the hot ICM is largely responsible for
regulating cooling and star formation in the cores of clusters, leading to the
significant growth of supermassive black holes in CDGs at late times.


title:
Asymptotic behaviour of randomly reflecting billiards in unbounded
  tubular domains

abstract:
  We study stochastic billiards in infinite planar domains with curvilinear
boundaries: that is, piecewise deterministic motion with randomness introduced
via random reflections at the domain boundary. Physical motivation for the
process originates with ideal gas models in the Knudsen regime, with particles
reflecting off microscopically rough surfaces. We classify the process into
recurrent and transient cases. We also give almost-sure results on the
long-term behaviour of the location of the particle, including a
super-diffusive rate of escape in the transient case. A key step in obtaining
our results is to relate our process to an instance of a one-dimensional
stochastic process with asymptotically zero drift, for which we prove some new
almost-sure bounds of independent interest. We obtain some of these bounds via
an application of general semimartingale criteria, also of some independent
interest.


title:
Temperature structure of the intergalactic medium within seven nearby
  and bright clusters of galaxies observed with XMM-Newton

abstract:
  Aims. We map the temperature structure of the intra-cluster medium (ICM)
within a nearly complete X-ray flux limited sample of galaxy clusters in the
redshift range z=[0.045,0.096]. Our sample contains seven bright clusters of
galaxies observed with XMM-Newton: Abell 399, Abell 401, Abell 478, Abell 1795,
Abell 2029, Abell 2065, Abell 2256.
  Methods. We use a multi-scale spectral mapping algorithm especially designed
to map spectroscopic observables from X-ray extended emission of the ICM.
Derived from a former algorithm using Haar wavelets, our algorithm is now
implemented with B-spline wavelets in order to perform a more regular analysis
of the signal.
  Results. For the four clusters in our sample that are major mergers, we find
a complex thermal structure with strong thermal variations consistent with
their dynamics. For two of them, A2065 and A2256, we perform a 3-d analysis of
cold front features evidenced from the gas temperature and brightness maps.
Furthermore, we detect a significant non-radial thermal structure outside the
cool core region of the other 3 more "regular" clusters, with relative
amplitudes of about about 10%. We investigate possible implications of this
structure on the mass estimates of the "regular" clusters A1795 and A2029, by
extracting surface brightness and temperature profiles from sectors
correspondings to the hottest and coldest regions in the maps. While
compensating with surface brightness for A2029, leading to consistent mass
profiles, the temperature structure leads to significant mass discrepancies in
the innermost region of A1795.


title: Holography constrains quantum bounce

abstract:
  Recent work in quantum loop cosmology suggests the universe undergoes a
bounce when evolving from a previous collapsing phase. However, with
non-inflationary matter sources, the scenario appears to strongly violate the
holography bound S\leq A/4 during the bounce, where A now represents the
cross-sectional area of the bounce. We also give a simple argument why any
inflationary phase after the bounce is unlikely due to prior dissipation of a
scalar field kinetic energy phase into regular matter components.


title:
Renormalization group for phases with broken discrete symmetry near
  quantum critical points

abstract:
  We extend the Hertz-Millis theory of quantum phase transitions in itinerant
electron systems to phases with broken discrete symmetry. Using a set of
coupled flow equations derived within the functional renormalization group
framework, we compute the second order phase transition line T_c(delta), with
delta a non-thermal control parameter, near a quantum critical point. We
analyze the interplay and relative importance of quantum and classical
fluctuations at different energy scales, and we compare the Ginzburg
temperature T_G to the transition temperature T_c, the latter being associated
with a non-Gaussian fixed-point.


title:
Random line tessellations of the plane: statistical properties of
  many-sided cells

abstract:
  We consider a family of random line tessellations of the Euclidean plane
introduced in a much more formal context by Hug and Schneider [Geom. Funct.
Anal. 17, 156 (2007)] and described by a parameter \alpha\geq 1. For \alpha=1
the zero-cell (that is, the cell containing the origin) coincides with the
Crofton cell of a Poisson line tessellation, and for \alpha=2 it coincides with
the typical Poisson-Voronoi cell. Let p_n(\alpha) be the probability for the
zero-cell to have n sides. By the methods of statistical mechanics we construct
the asymptotic expansion of \log p_n(\alpha) up to terms that vanish as
n\to\infty. In the large-n limit the cell is shown to become circular. The
circle is centered at the origin when \alpha>1, but gets delocalized for the
Crofton cell, \alpha=1, which is a singular point of the parameter range. The
large-n expansion of \log p_n(1) is therefore different from that of the
general case and we show how to carry it out. As a corollary we obtain the
analogous expansion for the {\it typical} n-sided cell of a Poisson line
tessellation.


title:
Gluon and ghost propagators in the Landau gauge: Deriving lattice
  results from Schwinger-Dyson equations

abstract:
  We show that the application of a novel gauge invariant truncation scheme to
the Schwinger-Dyson equations of QCD leads, in the Landau gauge, to an infrared
finite gluon propagator and a divergent ghost propagator, in qualitative
agreement with recent lattice data.


title:
AB-Net Method of Protection from Projectiles (city, military base,
  battle-front, etc.)

abstract:
  The author suggests a low cost special AB-Net from artificial fiber, which
may protect cities and important objects from rockets, artillery and mortar
shells, projectiles, bullets, and strategic weapons. The idea is as follows:
The offered AB-Net joins an incoming projectile to a small braking parachute
and this incoming projectile loses speed by air braking after a drag distance
of 50 - 150 meters. A following interception net after the first may serve to
collect the slowed projectiles and their fragments or bomblets so that they do
not reach the aimpoint. The author offers the design of AB-Net, a developed
theory of snagging with a small braking parachute by AB-Net; and sample
computations. These nets may be used for defense of a town, city, military
base, battle-front line, road (from terrorists), or any important objects or
installations (for example nuclear electric station, government buildings,
etc.). Computed projects are: Net to counter small rockets (for example, from
Qassam), net to counter artillery projectile (caliber 76 mm), net to counter
bullets (caliber 7.6 mm).
  The offered method is cheaper by thousands of times than protection of a city
by current anti-rocket systems. Discussion and results are at the end of the
article.
  Key words: Protection from missile and projectile weapons, mortar, rocket,
AB-Net, Qassam defense, incoming defense, armor.


title: The realization problem for von Neumann regular rings

abstract:
  We survey recent progress on the realization problem for von Neumann regular
rings, which asks whether every countable conical refinement monoid can be
realized as the monoid of isoclasses of finitely generated projective right
$R$-modules over a von Neumann regular ring $R$.


title: An introduction to the dark energy problem

abstract:
  In this work we review briefly the origin and history of the cosmological
constant and its recent reincarnation in the form of the dark energy component
of the universe. We also comment on the fundamental problems associated to its
existence and magnitude which require and urgent solution for the sake of the
internal consistency of theoretical physics.


title: Perturbative Gadgets at Arbitrary Orders

abstract:
  Adiabatic quantum algorithms are often most easily formulated using many-body
interactions. However, experimentally available interactions are generally
two-body. In 2004, Kempe, Kitaev, and Regev introduced perturbative gadgets, by
which arbitrary three-body effective interactions can be obtained using
Hamiltonians consisting only of two-body interactions. These three-body
effective interactions arise from the third order in perturbation theory. Since
their introduction, perturbative gadgets have become a standard tool in the
theory of quantum computation. Here we construct generalized gadgets so that
one can directly obtain arbitrary k-body effective interactions from two-body
Hamiltonians. These effective interactions arise from the kth order in
perturbation theory.


title: Cyclic Magnetic Universe

abstract:
  Recent works have shown the important role Nonlinear Electrodynamics (NLED)
can have in two crucial questions of Cosmology, concerning particular moments
of its evolution for very large and for low-curvature regimes, that is for very
condensed phase and at the present period of acceleration. We present here a
toy model of a complete cosmological scenario in which the main factor
responsible for the geometry is a nonlinear magnetic field which produces a FRW
homogeneous and isotropic geometry. In this scenario we distinguish four
distinct phases: a bouncing period, a radiation era, an acceleration era and a
re-bouncing. It has already been shown that in NLED a strong magnetic field can
overcome the inevitability of a singular region typical of linear Maxwell
theory; on the other extreme situation, that is for very weak magnetic field it
can accelerate the expansion. The present model goes one step further: after
the acceleration phase the universe re-bounces and enter in a collapse era.
This behavior is a manifestation of the invariance under the dual map of the
scale factor $ a(t) \to 1/ a(t),$ a consequence of the corresponding inverse
symmetry of the electromagnetic field ($ F \to 1/ F,$ where $F \equiv
F^{\mu\nu}F_{\mu\nu}$) of the NLED theory presented here. Such sequence
collapse-bouncing-expansion-acceleration-re-bouncing-collapse constitutes a
basic unitary element for the structure of the universe that can be repeated
indefinitely yielding what we call a Cyclic Magnetic Universe.


title: On the Rational Terms of the one-loop amplitudes

abstract:
  The various sources of Rational Terms contributing to the one-loop amplitudes
are critically discussed. We show that the terms originating from the generic
(n-4)-dimensional structure of the numerator of the one-loop amplitude can be
derived by using appropriate Feynman rules within a tree-like computation. For
the terms that originate from the reduction of the 4-dimensional part of the
numerator, we present two different strategies and explicit algorithms to
compute them.


title: Quantum continual measurements: the spectrum of the output

abstract:
  When a quantum system is monitored in continuous time, the result of the
measurement is a stochastic process. When the output process is stationary, at
least in the long run, the spectrum of the process can be introduced and its
properties studied. A typical continual measurement for quantum optical systems
is the so called homodyne detection. In this paper we show how the Heisenberg
uncertainty relations give rise to characteristic bounds on the possible
homodyne spectra and we discuss how this is related to the typical quantum
phenomenon of squeezing.


title: Geometric Scaling from GLAP evolution

abstract:
  We show that the geometric scaling of the total virtual photon-proton cross
section data can be explained using standard linear GLAP perturbative evolution
with generic boundary conditions in a wide kinematic region. This allows us to
single out the region where geometric scaling may provide evidence for parton
saturation.


title: Optimization of compact Soller collimator

abstract:
  The opportunity of optimization of collimator was investigated by changing
collimator length, material and wall roughness for soft x-ray radiation with
wavelength 4 nm corresponding to carbon atoms absorption. From the obtained
results follows that effects of diffraction become significant for channel
widths up to 0.02 - 0.04 mm. Collimation angle was limited to 0.014 and 0.007
radian for carbon dust detection. The choice of lighter material with greater
height of roughness in shorter collimator with 2 reflections results in
considerably lower losses than for heavier materials and smoother walls where 4
reflections required.


title:
Room temperature Epitaxial Stabilization of a Tetragonal Phase in ARuO3
  (A=Ca,Sr) Thin Films

abstract:
  We demonstrate that SrRuO3 and CaRuO3 thin films undergo a room temperature
structural phase transition driven by the substrate imposed epitaxial biaxial
strain. As tensile strain increases, ARuO3 (A=Ca, Sr) films transform from the
orthorhombic phase which is usually observed in bulk SrRuO3 and CaRuO3 at room
temperature, into a tetragonal phase which in bulk samples is only stable at
higher temperatures. More importantly, we show that the observed phenomenon
strongly affects the electronic and magnetic properties of ARuO3 thin films
that are grown on different single crystal substrates which in turn offers the
possibility to tune these properties.


title:
Investigating the transport of angular momentum from young stellar
  objects: do H2 jets from Class I YSOs rotate?

abstract:
  In this pilot study, we examine molecular jets from the embedded Class I
sources, HH 26 and HH 72, to search, for the first time, for kinematic
signatures of jet rotation from young embedded sources.High resolution
long-slit spectroscopy of the H2 1-0 S(1) transition was obtained using
VLT/ISAAC, position-velocity (PV) diagrams constructed and intensity-weighted
radial velocities transverse to the jet flow measured. Mean intensity-weighted
velocities vary between vLSR ~ -90 and -65 km/s for HH 26, and -60 and -10 km/s
for HH 72; maxima occur close to the intensity peak and decrease toward the jet
borders. Velocity dispersions are ~ 45 and ~ 80 km/s for HH 26 and HH 72,
respectively, with gas motions as fast as -100 km/s present. Asymmetric PV
diagrams are seen for both objects which a simple empirical model of a
cylindrical jet section shows could in principle be reproduced by jet rotation
alone. Assuming magneto-centrifugal launching, the observed HH 26 flow may
originate at a disk radius of 2-4 AU from the star with the toroidal component
of the magnetic field dominant at the observed location, in agreement with
magnetic collimation models. We estimate that the kinetic angular momentum
transported by the HH 26 jet is ~ 2E5 M_sun/yr AU km/s. This value (a lower
limit to the total angular momentum transported by the flow) already amounts to
70% of the angular momentum that has to be extracted from the disk for the
accretion to proceed at the observed rate.
  The results of this pilot study suggest that jet rotation may also be present
at early evolutionary phases and supports the hypothesis that they carry away
excess angular momentum, thus allowing the central protostar to increase its
mass.


title:
Quasiparticles, coherence and nonlinearity: exact simulations of
  RF-spectroscopy of strongly interacting one-dimensional Fermi gases

abstract:
  We consider RF-spectroscopy of ultracold Fermi gases by exact simulations of
the many-body state and the coherent dynamics in one dimension. Deviations from
the linear response sum rule result are found to suppress the pairing
contribution to the RF line shifts. We compare the coherent rotation and
quasiparticle descriptions of RF-spectroscopy which are analogous to NMR
experiments in superfluid $^3$He and tunneling in solids, respectively. We
suggest that RF-spectroscopy in ultracold gases provides an interesting
crossover between these descriptions that could be used for studying
decoherence in quantum measurement, in the context of many-body quantum states.


title: Thermonuclear Fusion with the Sheared Flow Stabilized Z-Pinch

abstract:
  Two basic approaches to producing thermonuclear fusion with a sheared flow
stabilized z-pinch are considered. One consists of heating the entire length of
the z-pinch column to the required temperatures. The other basic approach
considered here involves the concept of fast ignition. A localized "hot-spot"
is produced under the proper conditions to ignite a thermonuclear burn wave in
the z-pinch plasma. Here we demonstrate that sheared flow stabilization is more
efficient in the fast-ignition method with isentropic compression then in a
z-pinch where the entire plasma column is heated.


title: On the Complexity of Elementary Modal Logics

abstract:
  Modal logics are widely used in computer science. The complexity of modal
satisfiability problems has been investigated since the 1970s, usually proving
results on a case-by-case basis. We prove a very general classification for a
wide class of relevant logics: Many important subclasses of modal logics can be
obtained by restricting the allowed models with first-order Horn formulas. We
show that the satisfiability problem for each of these logics is either
NP-complete or PSPACE-hard, and exhibit a simple classification criterion.
Further, we prove matching PSPACE upper bounds for many of the PSPACE-hard
logics.


title: Electromagnetic Quantum Field Theory on Kerr-Newman Black Holes

abstract:
  We study classical and quantum aspects of electromagnetic perturbations on
black hole space-times. We develop an elegant formalism introduced by Wald,
which sets up the theory of linear perturbations in a Type-D background in a
compact and transparent manner. We derive expressions for the electromagnetic
potential in terms of the single Newman-Penrose scalar \phi_0.This enables the
formulation of the quantum theory of the electromagnetic field as that of a
complex scalar field.
  We study the separable field equations obeyed by the various Newman-Penrose
scalars in the Kerr-Newman background and find, for various limits, the
asymptotic behaviour of the radial and angular solutions. We correct and build
on a study by Breuer, Ryan and Waller to find a uniformly valid asymptotic
behaviour for large frequency of the angular solutions and the eigenvalues.
  We follow Candelas, Chrzanowski and Howard (CCH) in their canonical
quantization of the electromagnetic potential and field. We perform an
asymptotic analysis of the form of the renormalized stress-energy tensor (RSET)
in the past Boulware state close to the horizon. Unlike results in CCH, its
leading order behaviour close to the horizon corresponds to minus the stress
tensor of a thermal distribution at the Hawking temperature rigidly rotating
with the horizon. We prove that expressions in CCH for the expectation value of
the stress tensor in the past Boulware, past Unruh and |CCH> states lead to a
lack of symmetry of the RSET under parity, even though this is a symmetry of
the physical system. We derive the correct symmetric expressions and present a
detailed analysis of the resulting RSETs.


title: Abelian Varieties with Prescribed Embedding Degree

abstract:
  We present an algorithm that, on input of a CM-field $K$, an integer $k\ge1$,
and a prime $r \equiv 1 \bmod k$, constructs a $q$-Weil number $\pi \in \O_K$
corresponding to an ordinary, simple abelian variety $A$ over the field $\F$ of
$q$ elements that has an $\F$-rational point of order $r$ and embedding degree
$k$ with respect to $r$. We then discuss how CM-methods over $K$ can be used to
explicitly construct $A$.


title: Induced Measures on "Mu**"- measurable Sets

abstract:
  We investigate extension of a measure to a very general set of undetermined
structure. Structure may be imposed on this set in special cases


title:
Multi-hop Cooperative Wireless Networks: Diversity Multiplexing Tradeoff
  and Optimal Code Design

abstract:
  We consider single-source single-sink (ss-ss) multi-hop networks, with
slow-fading links and single-antenna half-duplex relays. We identify two
families of networks that are multi-hop generalizations of the well-studied
two-hop network: K-Parallel-Path (KPP) networks and layered networks. KPP
networks can be viewed as the union of K node-disjoint parallel relaying paths,
each of length greater than one. KPP networks are then generalized to KPP(I)
networks, which permit interference between paths and to KPP(D) networks, which
possess a direct link from source to sink. We characterize the DMT of these
families of networks completely for K > 3. Layered networks are networks
comprising of relaying layers with edges existing only within the same layer or
between adjacent layers. We prove that a linear DMT between the maximum
diversity d_{max} and the maximum multiplexing gain of 1 is achievable for
fully-connected layered networks. This is shown to be equal to the optimal DMT
if the number of layers is less than 4. For multi-antenna KPP and layered
networks, we provide an achievable DMT region.
  For arbitrary ss-ss single-antenna directed-acyclic full-duplex networks, we
prove that a linear tradeoff between maximum diversity and maximum multiplexing
gain is achievable. All protocols in this paper are explicit and use only
amplify and forward (AF) relaying. We also construct codes with short
block-lengths based on cyclic division algebras that achieve the optimal DMT
for all the proposed schemes. Two key implications of the results in the paper
are that the half-duplex constraint does not entail any rate loss for a large
class of networks and that simple AF protocols are often sufficient to attain
the optimal DMT.


title: Quasinormal modes and thermodynamic phase transitions

abstract:
  It has recently been suggested that scalar, Dirac and Rarita-Schwinger
perturbations are related to thermodynamic phase transitions of charged
(Reissner-Nordstr\"om) black holes. In this note we show that this result is
probably a numerical coincidence, and that the conjectured correspondence does
not straightforwardly generalize to other metrics, such as Kerr or
Schwarzschild (anti-)de Sitter. Our calculations do not rule out a relation
between dynamical and thermodynamical properties of black holes, but they
suggest that such a relation is non-trivial.


title: Photometric redshifts in the SWIRE Survey

abstract:
  We present the SWIRE Photometric Redshift Catalogue, 1025119 redshifts of
unprecedented reliability and accuracy. Our method is based on fixed galaxy and
QSO templates applied to data at 0.36-4.5 mu, and on a set of 4 infrared
emission templates fitted to infrared excess data at 3.6-170 mu. The code
involves two passes through the data, to try to optimize recognition of AGN
dust tori. A few carefully justified priors are used and are the key to
supression of outliers. Extinction, A_V, is allowed as a free parameter. We use
a set of 5982 spectroscopic redshifts, taken from the literature and from our
own spectroscopic surveys, to analyze the performance of our method as a
function of the number of photometric bands used in the solution and the
reduced chi^2. For 7 photometric bands the rms value of
(z_{phot}-z_{spec})/(1+z_{spec}) is 3.5%, and the percentage of catastrophic
outliers is ~1%.
  We discuss the redshift distributions at 3.6 and 24 mu. In individual fields,
structure in the redshift distribution corresponds to clusters which can be
seen in the spectroscopic redshift distribution. 10% of sources in the SWIRE
photometric redshift catalogue have z >2, and 4% have z>3, so this catalogue is
a huge resource for high redshift galaxies.
  A key parameter for understanding the evolutionary status of infrared
galaxies is L_{ir}/L_{opt}, which can be interpreted as the specific
star-formation rate for starbursts. For dust tori around Type 1 AGN,
L_{tor}/L_{opt} is a measure of the torus covering factor and we deduce a mean
covering factor of 40%.