title:
On Optimal Turbo Decoding of Wideband MIMO-OFDM Systems Under Imperfect
  Channel State Information

abstract:
  We consider the decoding of bit interleaved coded modulation (BICM) applied
to both multiband and MIMO OFDM systems for typical scenarios where only a
noisy (possibly very bad) estimate of the channel is provided by sending a
limited number of pilot symbols. First, by using a Bayesian framework involving
the channel a posteriori density, we adopt a practical decoding metric that is
robust to the presence of channel estimation errors. Then this metric is used
in the demapping part of BICM multiband and MIMO OFDM receivers. We also
compare our results with the performance of a mismatched decoder that replaces
the channel by its estimate in the decoding metric. Numerical results over both
realistic UWB and theoretical Rayleigh fading channels show that the proposed
method provides significant gain in terms of bit error rate compared to the
classical mismatched detector, without introducing any additional complexity.


title: Wavelet Based Semi-blind Channel Estimation For Multiband OFDM

abstract:
  This paper introduces an expectation-maximization (EM) algorithm within a
wavelet domain Bayesian framework for semi-blind channel estimation of
multiband OFDM based UWB communications. A prior distribution is chosen for the
wavelet coefficients of the unknown channel impulse response in order to model
a sparseness property of the wavelet representation. This prior yields, in
maximum a posteriori estimation, a thresholding rule within the EM algorithm.
We particularly focus on reducing the number of estimated parameters by
iteratively discarding ``unsignificant'' wavelet coefficients from the
estimation process. Simulation results using UWB channels issued from both
models and measurements show that under sparsity conditions, the proposed
algorithm outperforms pilot based channel estimation in terms of mean square
error and bit error rate and enhances the estimation accuracy with less
computational complexity than traditional semi-blind methods.


title: Dijet production in diffractive deep inelastic scattering at HERA

abstract:
  The production of dijets in diffractive deep inelastic scattering has been
measured with the ZEUS detector at HERA using an integrated luminosity of $61
\pbi$. The dijet cross section has been measured for virtualities of the
exchanged virtual photon, $5 < Q^2 < 100 \gev^2$, and $\gamma^{*} p$
centre-of-mass energies, 100 < W < 250 GeV. The jets, identified using the
inclusive k_{T} algorithm in the $\gamma^* p$ frame, were required to have a
transverse energy $E^*_{T, \rm jet} > 4 \gev$ and the jet with the highest
transverse energy was required to have $E^*_{T,\rm jet} > 5 \gev$. All jets
were required to be in the pseudorapidity range $-3.5 < \eta^*_{\rm jet} < 0$.
The differential cross sections are compared to leading-order predictions and
next-to-leading-order QCD calculations based on recent diffractive parton
densities extracted from inclusive diffractive deep inelastic scattering data.


title:
MIMO-OFDM Optimal Decoding and Achievable Information Rates Under
  Imperfect Channel Estimation

abstract:
  Optimal decoding of bit interleaved coded modulation (BICM) MIMO-OFDM where
an imperfect channel estimate is available at the receiver is investigated.
First, by using a Bayesian approach involving the channel a posteriori density,
we derive a practical decoding metric for general memoryless channels that is
robust to the presence of channel estimation errors. Then, we evaluate the
outage rates achieved by a decoder that uses our proposed metric. The
performance of the proposed decoder is compared to the classical mismatched
decoder and a theoretical decoder defined as the best decoder in the presence
of imperfect channel estimation. Numerical results over Rayleigh block fading
MIMO-OFDM channels show that the proposed decoder outperforms mismatched
decoding in terms of bit error rate and outage capacity without introducing any
additional complexity.


title: Symplectic surgeries and normal surface singularities

abstract:
  We show that every negative definite configuration of symplectic surfaces in
a symplectic 4--manifold has a strongly symplectically convex neighborhood. We
use this to show that, if a negative definite configuration satisfies an
additional negativity condition at each surface in the configuration, and if
the complex singularity with resolution diffeomorphic to a neighborhood of the
configuration has a smoothing, then the configuration can be symplectically
replaced by the smoothing of the singularity. This generalizes the symplectic
rational blowdown procedure used in recent constructions of small exotic
4--manifolds.


title:
Dynamical generalization of a solvable family of two-electron model
  atoms with general interparticle repulsion

abstract:
  Holas, Howard and March [Phys. Lett. A {\bf 310}, 451 (2003)] have obtained
analytic solutions for ground-state properties of a whole family of
two-electron spin-compensated harmonically confined model atoms whose different
members are characterized by a specific interparticle potential energy
u($r_{12}$). Here, we make a start on the dynamic generalization of the
harmonic external potential, the motivation being the serious criticism
levelled recently against the foundations of time-dependent density-functional
theory (e.g. [J. Schirmer and A. Dreuw, Phys. Rev. A {\bf 75}, 022513 (2007)]).
In this context, we derive a simplified expression for the time-dependent
electron density for arbitrary interparticle interaction, which is fully
determined by an one-dimensional non-interacting Hamiltonian. Moreover, a
closed solution for the momentum space density in the Moshinsky model is
obtained.


title: On Local Integrability Conditions Of Jet Groupoids

abstract:
  A Jet groupoid R_q over a manifold X is a special Lie groupoid consisting of
q-jets of local diffeomorphisms from X to X. As a subbundle of the q-th order
jet bundle of the trivial bundle X times X, a jet groupoid can be considered as
a nonlinear system of partial differential equations (PDE). This leads to the
concept of formal integrability. On the other hand, each jet groupoid is the
symmetry groupoid of a geometric object, modelled as a section of a natural
bundle. Using the jet groupoids, we give a local characterisation of formal
integrability for transitive jet groupoids in terms of their corresponding
geometric objects.


title: Do we Live in a "Small Universe"?

abstract:
  We compute the effects of a compact flat universe on the angular correlation
function, the angular power spectrum, the circles-in-the-sky signature, and the
covariance matrix of the spherical harmonics coefficients of the cosmic
microwave background radiation using the full Boltzmann physics. Our analysis
shows that the Wilkinson Microwave Anisotropy Probe (WMAP) three-year data are
well compatible with the possibility that we live in a flat 3-torus with volume
~5x10^3 Gpc^3.


title:
Roles of the quark field in the infrared lattice Coulomb gauge and
  Landau gauge QCD

abstract:
  The effective coupling of QCD is measured by using the gauge configurations
produced by the MILC collaboration in which the Kogut Susskind (KS) fermion is
incorporated and by using that produced by the QCDOC collaboration in which the
domain wall fermion (DWF) is incorporated. We fix the gauge to the Landau gauge
and to the Coulomb gauge. The infrared effective coupling in the Coulomb gauge
agrees with the recent extraction at JLab, but that in the Landau gauge shows
infrared suppression. The suppression is expected to be due to the color
anti-symmetric ghost propagator which in the unquenched configurations has
stronger infrared singularity than the color diagonal ghost propagator. The
Coulomb form factor in the infrared depends on the kind of the fermion
incorporated in the system and the temperature. The quark has the effect of
quenching randomness and the fluctuation of the color anti-symmetric ghost
propagator is reduced in the unquenched configuration, and the Kugo-Ojima
parameter c is closer to 1 in the unquenched configuration than in the quenched
configuration.


title:
HI Clouds detected towards Virgo with the Arecibo Legacy Fast ALFA
  Survey

abstract:
  The Arecibo Legacy Fast ALFA survey is in the process of yielding a complete
HI dataset of the Virgo Cluster and its environs (Giovanelli et al. 2007, Kent
et al., in preparation). Assuming a distance to Virgo of 16.7 Mpc, the minimum
detectable HI mass by ALFALFA is of order 2 x 10^7 Msun. A number of the HI
detections appear to have interesting properties. Some appear associated with,
but offset from, low surface brightness optical counterparts; others, at larger
spatial offsets, may be tidally related to optical counterparts. Yet another
class includes detections which are not identifiable with any optical
counterparts. We present the ALFALFA results on these objects in the Virgo
region, as well as followup aperture synthesis observations obtained with the
VLA.


title: A property of cyclotomic polynomials

abstract:
  Given two cyclotomic polynomials $\Phi_n(x)$ and $\Phi_m(x)$, $n\not= m$, we
determine the minimal natural number k such that we can write $$k=a(x)\Phi_n
(x)+b(x)\Phi_m(x),$$ with a(x) and b(x) integer polynomials.


title:
Charge and spin response functions for the Tomonaga model with quadratic
  dispersion and different interactions

abstract:
  We derive expressions for the charge and spin response function for the
Tomonaga model with quadratic dispersion and arbitrary (but finite for zero
momentum) interaction. For constant interaction these expressions are analytic
and for other types of interaction only a simple matrix has to be diagonalised.
We use a truncated expansion in particle-hole states with and without inclusion
of correlations in the ground state yielding an exact result for pure
intra-band interaction. We also discuss the possibility of power-laws in the
dynamic structure factor for the spinful and spinless model.


title: Convergence analysis of the B\"ol-Reese discrete model for rubber

abstract:
  In a recent work, B\"ol and Reese have introduced a discrete model for
polymer networks by means of a finite element modeling. They have also provided
a comparison with real experiments. A key parameter of their model is the size
h of the finite element mesh, that is meant to be small in practice. The aim of
the present work is to study the asymptotic behaviour (and the convergence of
the finite element method) when the meshsize goes to zero. In particular, we
address the properties satisfied by the model at the limit, depending on the
properties of the mesh.


title:
A Comparison between 1.5$\mu$m Photoluminescence from Er-Doped Si-Rich
  Sio2 Films and (Er,Ge) Co-Doped Sio2 Films

abstract:
  We have studied the 1.5 $\mu$m photoluminescence (PL) from Er ions after
annealing two different sample sets in the temperature range 500 °C to 1100
°C. The different sample sets were made by magnetron sputtering from
composite targets of Si+SiO2+Er and Ge+SiO2+Er respectively for the different
sample sets. The annealing induces Si - and Ge-nanoclusters respectively in the
different film sets. The PL peak reaches its maximum intensity after annealing
at 700 °C for samples with Ge nanoclusters and after annealing at 800
°C for samples with Si. No luminescence from nanoclusters was detected in
neither sample sets. This is interpreted as an energy transfer from the
nanocluster to Er atoms. Transmission electron microscopy shows that after
annealing to the respective temperature yielding the maximum PL intensity both
the Ge and Si clusters are non-crystalline. Here we mainly compare the spectral
shape of Er luminescence emitted in these different nanostructured matrixes.
The PL spectral shapes are clearly different and witness a different local
environment for the Er ions.


title: Infrared Emission from the Nearby Cool Core Cluster Abell 2597

abstract:
  We observed the brightest central galaxy (BCG) in the nearby (z=0.0821) cool
core galaxy cluster Abell 2597 with the IRAC and MIPS instruments on board the
Spitzer Space Telescope. The BCG was clearly detected in all Spitzer
bandpasses, including the 70 and 160 micron wavebands. We report aperture
photometry of the BCG. The spectral energy distribution exhibits a clear excess
in the FIR over a Rayleigh-Jeans stellar tail, indicating a star formation rate
of ~4-5 solar masses per year, consistent with the estimates from the UV and
its H-alpha luminosity. This large FIR luminosity is consistent with that of a
starburst or a Luminous Infrared Galaxy (LIRG), but together with a very
massive and old population of stars that dominate the energy output of the
galaxy. If the dust is at one temperature, the ratio of 70 to 160 micron fluxes
indicate that the dust emitting mid-IR in this source is somewhat hotter than
the dust emitting mid-IR in two BCGs at higher-redshift (z~0.2-0.3) and higher
FIR luminosities observed earlier by Spitzer, in clusters Abell 1835 and Zwicky
3146.


title:
Qualitative properties of coupled parabolic systems of evolution
  equations

abstract:
  We apply functional analytical and variational methods in order to study
well-posedness and qualitative properties of evolution equations on product
Hilbert spaces. To this aim we introduce an algebraic formalism for matrices of
sesquilinear mappings. We apply our results to parabolic problems of different
nature: a coupled diffusive system arising in neurobiology, a strongly damped
wave equation, a heat equation with dynamic boundary conditions, and a general
semilinear Hodgkin--Huxley sytem.


title: Data analysis methods for the cosmic microwave background

abstract:
  In this review, we give an overview of some of the major aspects of data
reduction and analysis for the cosmic microwave background (CMB). Since its
prediction and discovery in the last century, the CMB radiation has proven
itself to be one of our most valuable tools for precision cosmology. Recently,
and especially when combined with complementary cosmological data, measurements
of the CMB anisotropies have provided us with a wealth of quantitive
information about the birth, evolution and structure of our Universe. We begin
with a simple, general introduction to the physics of the CMB, including a
basic overview of the experiments which record CMB data. The focus, however,
will be the data analysis treatment of CMB data sets.


title:
Determinants related to Dirichlet characters modulo 2, 4 and 8 of
  binomial coefficients and the algebra of recurrence matrices

abstract:
  Using recurrence matrices, defined and described with some details, we study
a few determinants related to evaluations of binomial coefficients on Dirichlet
characters modulo 2, 4 and 8.


title:
Gradient estimates for a degenerate parabolic equation with gradient
  absorption and applications

abstract:
  Qualitative properties of non-negative solutions to a quasilinear degenerate
parabolic equation with an absorption term depending solely on the gradient are
shown, providing information on the competition between the nonlinear diffusion
and the nonlinear absorption. In particular, the limit as time goes to infinity
of the mass of integrable solutions is identified, together with the rate of
expansion of the support for compactly supported initial data. The persistence
of dead cores is also shown. The proof of these results strongly relies on
gradient estimates which are first established.


title:
Low temperature heat capacity of Fe_{1-x}Ga_{x} alloys with large
  magneostriction

abstract:
  The low temperature heat capacity C_{p} of Fe_{1-x}Ga_{x} alloys with large
magnetostriction has been investigated. The data were analyzed in the standard
way using electron ($\gamma T$) and phonon ($\beta T^{3}$) contributions. The
Debye temperature $\Theta_{D}$ decreases approximately linearly with increasing
Ga concentration, consistent with previous resonant ultrasound measurements and
measured phonon dispersion curves. Calculations of $\Theta_{D}$ from lattice
dynamical models and from measured elastic constants C_{11}, C_{12} and C_{44}
are in agreement with the measured data. The linear coefficient of electronic
specific heat $\gamma$ remains relatively constant as the Ga concentration
increases, despite the fact that the magnetoelastic coupling increases. Band
structure calculations show that this is due to the compensation of majority
and minority spin states at the Fermi level.


title: On exact solutions of a class of fractional Euler-Lagrange equations

abstract:
  In this paper, first a class of fractional differential equations are
obtained by using the fractional variational principles. We find a fractional
Lagrangian $L(x(t)$, where $_a^cD_t^\alpha x(t))$ and $0<\alpha< 1$, such that
the following is the corresponding Euler-Lagrange %
\begin{equation}_tD_b^\alpha(_a^cD_t^\alpha) x(t)+ b(t,x(t))(_a^cD_t^\alpha
x(t))+f(t,x(t))=0. \end{equation} % At last, exact solutions for some
Euler-Lagrange equations are presented. In particular, we consider the
following equations % \begin{equation}_tD_b^\alpha(_a^cD_t^\alpha x(t))=\lambda
x(t), (\lambda\in R) \end{equation} %
\begin{equation}_tD_b^\alpha(_a^cD_t^\alpha x(t))+g(t)_a^cD_t^\alpha x(t)=f(t),
\end{equation} where g(t) and f(t) are suitable functions.


title:
Coefficient of Restitution for Viscoelastic Spheres: The Effect of
  Delayed Recovery

abstract:
  The coefficient of normal restitution of colliding viscoelastic spheres is
computed as a function of the material properties and the impact velocity. From
simple arguments it becomes clear that in a collision of purely repulsively
interacting particles, the particles loose contact slightly before the distance
of the centers of the spheres reaches the sum of the radii, that is, the
particles recover their shape only after they lose contact with their collision
partner. This effect was neglected in earlier calculations which leads
erroneously to attractive forces and, thus, to an underestimation of the
coefficient of restitution. As a result we find a novel dependence of the
coefficient of restitution on the impact rate.


title: Model Studies on the Quantum Jarzynski Relation

abstract:
  We study the quantum Jarzynski relation for driven quantum models embedded in
various environments. We do so by generalizing a proof presented by Mukamel
[Phys. Rev. Lett 90, 170604 (2003)] for closed quantum systems. In this way, we
are able to prove that the Jarzynski relation also holds for a bipartite system
with microcanonical coupling. Furthermore, we show that, under the assumption
that the interaction energy remains constant during the whole process, the
relation is valid even for canonical coupling. The same follows for open
quantum systems at high initial temperatures up to third order of the inverse
temperature. Our analytical study is complemented by a numerical investigation
of a special model system.


title: Transport properties of double-walled carbon nanotube quantum dots

abstract:
  The transport properties of quantum dot (QD) systems based on double-walled
carbon nanotube (DWCNT) are investigated. The interplay between microscopic
structure and strong Coulomb interaction is treated within a bosonization
framework. The linear and nonlinear G-V-V_g characteristics of the QD system is
calculated by starting from the Liouville equation for the reduced density
matrix. Depending on the intershell couplings, an 8-electron periodicity of the
Coulomb blockade peak spacing in the case of commensurate DWCNT QDs and a
4-electron periodicity in the incommensurate case are predicted. The
contribution of excited states of DWCNTs to the nonlinear transport is
investigated as well.


title: Twisted cohomology of the Hilbert schemes of points on surfaces

abstract:
  We calculate the cohomology spaces of the Hilbert schemes of points on
surfaces with values in locally constant systems. For that purpose, we
generalise I. Grojnoswki's and H. Nakajima's description of the ordinary
cohomology in terms of a Fock space representation to the twisted case. We
further generalise M. Lehn's work on the action of the Virasoro algebra to the
twisted case.
  Building on work by M. Lehn and Ch. Sorger, we then give an explicit
description of the cup-product in the twisted case whenever the surface has a
numerically trivial canonical divisor.
  We formulate our results in a way that they apply to the projective and
non-projective case in equal measure.
  As an application of our methods, we give explicit models for the cohomology
rings of the generalised Kummer varieties and of a series of certain even
dimensional Calabi--Yau manifolds.


title: Particle acceleration in relativistic subluminal shock environments

abstract:
  The understanding of the particle spectra resulting from acceleration in
relativistic shocks as they occur in extragalactic sources, is essential for
the interpretation of the cosmic ray spectrum above the ankle ($E_p>3\cdot
10^{18}$ eV). It is believed that extragalactic sources like Active Galactic
Nuclei and Gamma Ray Bursts can produce particle spectra up to $E_p\sim
10^{21}$ eV. In this contribution, subluminal shocks are investigated with
respect to different shock boost factors $\Gamma$ and the inclination angle
between the shock normal and the magnetic field $\psi$. A correlation between
the boost factor and the spectral behavior of the emitted particles is found.
The results are compared to Active Galactic Nuclei and Gamma Ray Burst diffuse
cosmic ray contribution and the observed cosmic ray spectrum at the highest
energies.


title: The Optimal Form of Distribution Networks Applied to the Kidney and Lung

abstract:
  A model is proposed to minimize the total volume of the main distribution
networks of fluids in relation to the organ form. The minimization analysis
shows that the overall exterior form of distribution networks is a modified
ellipsoid, a geometric form that is a good approximation to the external
anatomy of the kidney and lung. The variational procedure implementing this
minimization is similar to the traditional isoperimetric theorems of geometry.
  A revised version of this preprint that expands Section 4 will be published
in the Journal of Biological Systems, World Scientific Publishing.


title: The Disk Mass of Spiral Galaxies

abstract:
  We derive the disk masses of 18 spiral galaxies of different luminosity and
Hubble Type, both by mass modelling their rotation curves and by fitting their
SED with spectro-photometric models. The good agreement of the estimates
obtained from these two different methods allows us to quantify the reliability
of their performance and to derive very accurate stellar mass-to-light ratio vs
color (and stellar mass) relationships.


title: The Cosmic Web: Geometric Analysis

abstract:
  The lecture notes describe the Delaunay Tessellation Field Estimator for
Cosmic Web analysis. The high sensitivity of Voronoi/Delaunay tessellations to
the local point distribution is used to obtain estimates of density and related
quantities. The adaptive and minimum triangulation properties of Delaunay
tessellations are utilized for interpolation to continuous volume-covering
density and velocity fields. The adaptivity to the local density and geometry
preserves three key characteristics of the cosmic matter distribution: 1) its
hierarchical nature,2) its anisotropic weblike morphology, 3) the presence and
structure of voids. The lecture notes discuss the mathematical context and
background of the DTFE method, in essence a first order version of Natural
Neighbour methods, smooth and higher order spatial interpolation techniques.
This is followed by an outline of the DTFE procedure. A series of tests on
spatially complex point distributions provides quantitative information on its
performance and noise characteristics. We conclude with a few cosmological
applications. The reconstruction of the spatial weblike patterns in N-body
simulations and in the 2dFGRS provide a visual impression of DTFE's
performance. The analysis of the velocity divergence pdf and maps obtained of
the velocity flow in the Local Universe (implied by PSCz) illustrate its
promise for probing the dynamics of cosmic structure. The Watershed Void Finder
(Platen et al. 2007), for the study of voids, and Multiscale Morphology Filter
(Aragon-Calvo et al. 2007), for identifying and analyzing weblike networks of
filaments, sheets and clusters, are based upon DTFE density fields. We also
mention SimpleX, a related random lattice radiative transfer formalism
(Ritzerveld & Icke 2006).


title: Cosmic ray acceleration at modified shocks

abstract:
  The non-linear back reaction of accelerated cosmic rays at the shock fronts,
leads to the formation of a smooth precursor with a length scale corresponding
to the diffusive scale of the energetic particles. Past works claimed that
shocklets could be created in the precursor region of a specific shock width,
which might energize few thermal particles to sufficient acceleration and
furthermore this precursor region may act as confining large angle scatterer
for very high energy cosmic rays. On the other hand, it has been shown that the
smoothing of the shock front could lower the acceleration efficiency. These
controversies motivated us to investigate numerically by Monte Carlo
simulations the particle acceleration efficiency in oblique modified shocks.
The results show flatter spectra compared to the spectra of the pressumed sharp
discontinuity shock fronts. The findings are in accordance with theoretical
predictions, since the scattering inside the precursor confines high energy
particles to further scattering, resulting in higher energies making the whole
acceleration process more efficient.


title:
Measurement of D^0, D^+, D_s^+ and D^{*+} Production in Fixed Target 920
  GeV Proton-Nucleus Collisions

abstract:
  The inclusive production cross sections of the charmed mesons D^0, D^+, D_s^+
and D^{*+} have been measured in interactions of 920 GeV protons on C, Ti, and
W targets with the HERA-B detector at the HERA storage ring. Differential cross
sections as a function of transverse momentum and Feynman's x variable are
given for the central rapidity region and for transverse momenta up to
$\pT=3.5$ GeV/$c$. The atomic mass number dependence and the leading to
non-leading particle production asymmetries are presented as well.


title: Efficiency limits of diffusive shock acceleration

abstract:
  It is well accepted today that diffusive acceleration in shocks results to
the cosmic ray spectrum formation. This is in principle true for
non-relativistic shocks, since there is a detailed theory covering a large
range of their properties and the resulting power-law spectrum, which is
nevertheless not as efficient to reach the very high energies observed in the
cosmic ray spectrum. On the other hand, the cosmic ray maximum energy and the
resulting spectra from relativistic shocks, are still under investigation and
debate concerning their contribution to the features of the cosmic ray spectrum
and the measured, or implied, cosmic ray radiation from candidate astrophysical
sources. Here, we discuss the efficiency of the first order Fermi (diffusive)
acceleration mechanism up to relativistic shock speeds, presenting Monte Carlo
simulations.


title: Nanostructures, Magnetic Semiconductors and Spinelectronics

abstract:
  A short overview is given of recent advances in the field of
nanosemiconductors, which are suitable as materials for spin polarized
transport of charge carriers. On the basis of last theoretical and experimental
achievements it is shown that development of diluted and wide forbidden zone
semiconductors with controlled disorders as well as their molecular structures
is the very prospective way for magnetic semiconductors preparation.


title: Capillary wave turbulence on a spherical fluid surface in low gravity

abstract:
  We report the observation of capillary wave turbulence on the surface of a
fluid layer in a low-gravity environment. In such conditions, the fluid covers
all the internal surface of the spherical container which is submitted to
random forcing. The surface wave amplitude displays power-law spectrum over two
decades in frequency, corresponding to wavelength from $mm$ to a few $cm$. This
spectrum is found in roughly good agreement with wave turbulence theory. Such a
large scale observation without gravity waves has never been reached during
ground experiments. When the forcing is periodic, two-dimensional spherical
patterns are observed on the fluid surface such as subharmonic stripes or
hexagons with wavelength satisfying the capillary wave dispersion relation.

categories: cond-mat.other nlin.CD physics.class-ph physics.flu-dyn


title: On the adhesion of particles to a cell layer under flow

abstract:
  The non-specific adhesion of spherical particles to a cell substrate is
analyzed in a parallel plate flow chamber, addressing the effect of the
particle size. Differently from other experiments, the total volume of the
injected particles has been fixed, rather than the total number of particles,
as the diameter d of the particles is changed from 500 nm up to 10 $\mu$m. From
the analysis of the experimental data, simple and instructive scaling adhesion
laws have been derived showing that (i) the number of particles adherent to the
cell layer per unit surface decreases with the size of the particle as d^(-1.7)
; and consequently (ii) the volume of the particles adherent per unit surface
increases with the size of the particles as d^(+1.3). These results are of
importance in the "rational design" of nanoparticles for drug delivery and
biomedical imaging.


title:
Coherent quasiparticle transport in grain boundary junctions employing
  high-Tc superconductors

abstract:
  Magneto-fluctuations of the normal resistance RN have been reproducibly
observed in YBa2Cu3O7-d biepitaxial grain boundary junctions at low
temperatures. We attribute them to mesoscopic transport in narrow channels
across the grain boundary line, occurring in an unusual energy regime. The
Thouless energy appears to be the relevant energy scale. Possible implications
on the understanding of coherent transport of quasiparticles in HTS and of the
dissipation mechanisms are discussed.


title: Slow beams of massive molecules

abstract:
  Slow beams of neutral molecules are of great interest for a wide range of
applications, from cold chemistry through precision measurements to tests of
the foundations of quantum mechanics. We report on the quantitative observation
of thermal beams of perfluorinated macromolecules with masses up to 6000 amu,
reaching velocities down to 11 m/s. Such slow, heavy and neutral molecular
beams are of importance for a new class of experiments in matter-wave
interferometry and we also discuss the requirements for further manipulation
and cooling schemes with molecules in this unprecedented mass range.

categories: quant-ph physics.atm-clus physics.bio-ph physics.chem-ph


title: Pi-Molecular dielectric layer for organic thin film diode

abstract:
  Very thin (1.2-2.5nm) self-assembled organic dielectric monolayers have been
integrated into organic thin-film diode to achieve electrical characteristics.
These dielectrics are fabricated by self-assembling deposition, resulting in
smooth, strongly adherent, thermally stable, organosiloxane thin films having
interesting electrical capacitances (around 150 nF cm-2 at -3V) and insulating
properties (leakage current densities around 10-5 A cm2 at -1V).


abstract:
  We propose a Minimal E_6 Supersymmetric Standard Model (ME$_6$SSM) which
allows Planck scale unification, provides a solution to the $\mu$ problem and
predicts a new Z'. Above the conventional GUT scale $M_{GUT}\sim 10^{16}$ GeV
the gauge group corresponds to a left-right symmetric Supersymmetric Pati-Salam
model, together with an additional $U(1)_{\psi}$ gauge group arising from an
E_6 gauge group broken near the Planck scale. Below $M_{GUT}$ the ME$_6$SSM
contains three reducible $\mathbf{27}$ representations of the Standard Model
gauge group together with an additional U(1)_X gauge group, consisting of a
novel and non-trivial linear combination of $U(1)_{\psi}$ and two Pati-Salam
generators, which is broken at the TeV scale by the same singlet which also
generates the effective $\mu$ term, resulting in a new low energy Z' gauge
boson. We discuss the phenomenology of the new Z' gauge boson in some detail.


title: Holding Dissapearance in RTD-based Quantizers

abstract:
  Multiple-valued Logic (MVL) circuits are one of the most attractive
applications of the Monostable-to-Multistable transition Logic (MML), and they
are on the basis of advanced circuits for communications. The operation of such
quantizer has two steps : sampling and holding. Once the quantizer samples the
signal, it must maintain the sampled value even if the input changes. However,
holding property is not inherent to MML circuit topologies. This paper analyses
the case of an MML ternary inverter used as a quantizer, and determines the
relations that circuit representative parameters must verify to avoid this
malfunction.


title: Nano Calculators

abstract:
  The whole circuit is obtained from the sun through a molecule called
"Rhodopsin and bacteriorhodopsin". These molecules have the capability of
trapping and storing energy from the sun light. These molecules are placed on
the outer surface of the calculator to trap the energy and store it themselves
for latter usage. The thickness of the whole circuit measures less than
300nm.The top layer is made up of layer which will show the different keys and
a display unit. "Molecules are not only meant for compounding But also for
computing".


title: Cell Architecture for Nanoelectronic Design

abstract:
  Several nanoelectronic devices have been already proved. However, no
architecture which makes use of them provides a feasible opportunity to build
medium/large systems. Nanoarchitecture proposals only solve a small part of the
problems needed to achieve a real design. In this paper, we propose and analyze
a cell architecture that overcomes most of those at the gate level. Using the
cell structure we build 2 and 3-input NAND gates showing their error
probabilities. Finally, we outline a method to further improve the structure's
tolerance by taking advantage of interferences among nanodevices. Using this
improvement we show that it is possible to reduce the output standard deviation
by a factor larger than $\sqrt{2}$ and restitute the signal levels using
nanodevices.


title: Towards a Holistic CAD Platform for Nanotechnologies

abstract:
  Silicon-based CMOS technologies are predicted to reach their ultimate limits
by the middle of the next decade. Research on nanotechnologies is actively
conducted, in a world-wide effort to develop new technologies able to maintain
the Moore's law. They promise revolutionizing the computing systems by
integrating tremendous numbers of devices at low cost. These trends will have a
profound impact on the architectures of computing systems and will require a
new paradigm of CAD. The paper presents a work in progress on this direction.
It is aimed at fitting requirements and constraints of nanotechnologies, in an
effort to achieve efficient use of the huge computing power promised by them.
To achieve this goal we are developing CAD tools able to exploit efficiently
these huge computing capabilities promised by nanotechnologies in the domain of
simulation of complex systems composed by huge numbers of relatively simple
elements.


title:
Nanostructured Immunosensors. Application to the detection of
  Progesterone

abstract:
  A novel nanostructured electrochemical immunsensor for the determination of
progesterone is reported. The approach combines the properties of gold
nanoparticles with the use of a graphite-Teflon composite electrode matrix,
into which gold nanoparticles are incorporated by simple physical inclusion.
The antibody anti-progesterone was directly attached to the electrode surface.
The immunosensor functioning is based on competitive assay between progesterone
and alkaline phosphatase-labelled progesterone. Monitoring of the affinity
reaction was accomplished by the electrochemical oxidation of 1-naphtol.
Modification of the graphite -Teflon electrode matrix with gold nanoparticles
improves substantially the electrooxidation response of 1-naphtol. Using a
detection potential of +0.3V, a detection limit for progesterone of 0.84 ng
ml-1 was obtained. Analysis of seven milk samples spiked at a 3.5 ng ml-1
progesterone concentration level yielded a mean recovery of 101+6%. Detection
of the antigen-antibody reaction with a graphite - Teflon - colloidal - gold -
Tyrosinase electrode, using phenylphosphate as alkaline phosphatase substrate
to generate phenol, which is subsequently reduced at -0.1 V at the composite
electrode, produced a high improvement in the sensitivity for progesterone
detection


title: Fusion Phage as a Bioselective Nanomaterial : Evolution of the Concept

abstract:
  Multibillion-clone landscape phage display libraries were prepared by the
fusion of the phage major coat protein pVIII with foreign random peptides.
Phage particles and their proteins specific for cancer and bacterial cells were
selected from the landscape libraries and exploited as molecular recognition
interfaces in detection, gene- and drug-delivery systems. The biorecognition
interfaces were obtained by incorporation of the cell-specific phage fusion
proteins into liposomes using intrinsic structural duplicity of the proteins.
As a paradigm, we incorporated targeted pVIII proteins into commercially
available therapeutic liposomes "Doxil", which acquired a new emergent
property-ability to bind target receptors. Targeting of the drug was evidenced
by fluorescence-activated cell sorting, microarray, optical and electron
microscopy. In contrast to a poorly controllable conjugation targeting, the new
landscape phage-based approach relies on very powerful and extremely precise
mechanisms of selection, biosynthesis and self assembly, in which phages
themselves serve as a source of the final product.


title: DNA Nanorobotics

abstract:
  This paper presents a molecular mechanics study for new nanorobotic
structures using molecular dynamics (MD) simulations coupled to virtual reality
(VR) techniques. The operator can design and characterize through molecular
dynamics simulation the behavior of bionanorobotic components and structures
through 3-D visualization. The main novelty of the proposed simulations is
based on the mechanical characterization of passive/active robotic devices
based on double stranded DNA molecules. Their use as new DNA-based nanojoint
and nanotweezer are simulated and results discussed.


title:
To study the effects of degradation of phonon distribution on the high
  frequency response in nano structures

abstract:
  Under hot electron condition, the hot carriers phonon excited by ultra-short
pulses in polar semiconductors initially loose energy rapidly by emitting
longitudinal optic phonons via dominant Frolic coupling. Thus, energy supplied
to the carriers by high electric fields goes into phonon generation. As the
phonon life time is long enough, phonon distribution is disturbed and a non
equilibrium population of LO phonons or hot phonons are produced, leading to
their re-absorption by the carriers. In the present work the high frequency
performance of GaN nanostructures is studied in the framework of heated drifted
Fermi-Dirac distribution function incorporating the relevant scattering
mechanisms and the influence of non-equilibrium LO phonons. It is observed that
degradation of phonon distribution enhances significantly 3-dB cut off
frequency thereby makes the high frequency response flatter reflecting that
high frequency response is better if effects of non-equilibrium phonon
distributions are included in the calculations.


title: Warm inflation in the DGP brane-world model

abstract:
  Warm inflationary universe models on a warped Dvali-Gabadadze-Porrati brane
are studied. General conditions required for these models to be realizable are
derived and discussed. By using an effective exponential potential we develop
models for constant and variable dissipation coefficient ratio
$r=\frac{\Gamma}{3 H}$. We use recent astronomical observations for
constraining the parameters appearing in our models.


title: Production and application of metal-based nanoparticles

abstract:
  A number of metal-based nanopowders such kinds as Fe, Co, Fe/Co alloy, Fe/C,
Fe/organic shell were successfully produced by aerosol synthesis method. The
mechanism of nanoparticles formation and the influence of experimental
parameters on shape, size distribution, structure, chemical and phase
composition of oxide-, carbon-, or organic- coated nanoparticles were
evaluated. The sizes of particles can be varied from 6-100 nm with narrow size
distribution. The several application fields of synthesized nanoparticles have
been studied.


title:
Structural Characterization of Magnetic Nano-particles Suspensions,
  Using Magnetic Measurements

abstract:
  The paper describes some characteristics of the "P" curves for structural
characterization of magnetic nano-particles suspensions (complex fluids,
complex powders, complex composite materials, or living biological materials
having magnetic properties). In the case of these materials, the magnetic
properties are conferred to various carrier liquids by artificially integrating
in their structure ferromagnetic particles of different sizes. The magnetic
properties are usually shown by the hysteresis curve. The structure can be seen
on (electronic) micrography. The P curves offer another possibility to
determine the structure of the magnetic component of a complex fluid by
numerical analysis of the magnetization curve experimentally obtained. The
paper presents a detailed approach of the P curves and some limitations in
their use.


title: Light scalar at LHC: the Higgs or the dilaton?

abstract:
  It is likely that the LHC will observe a color- and charge-neutral scalar
whose decays are consistent with those of the Standard Model (SM) Higgs boson.
The Higgs interpretation of such a discovery is not the only possibility. For
example, electroweak symmetry breaking (EWSB) could be triggered by a
spontaneously broken, nearly conformal sector. The spectrum of states at the
electroweak scale would then contain a narrow scalar resonance, the
pseudo-Goldstone boson of conformal symmetry breaking, with Higgs-like
properties. If the conformal sector is strongly coupled, this pseudo-dilaton
may be the only new state accessible at high energy colliders. We discuss the
prospects for distinguishing this mode from a minimal Higgs boson at the LHC
and ILC. The main discriminants between the two scenarios are (1) cubic
self-interactions and (2) a potential enhancement of couplings to massless SM
gauge bosons. A particularly interesting situation arises when the scale f of
conformal symmetry breaking is approximately the electroweak scale v~246 GeV.
Although in this case the LHC may not be able to tell apart a pseudo-dilaton
from the Higgs boson, the self-interactions differ in a way that depends only
on the scaling dimension of certain operators in the conformal sector. This
opens the possibility of using dilaton pair production at future colliders as a
probe of EWSB induced by nearly conformal new physics.


title: Batch fabrication of cluster assembled microarrays for chemical sensing

abstract:
  Deposition of clusters from the gas phase is becoming an enabling technology
for the production of nanostructured devices. Supersonic clusters beam
deposition (SCBD) has been shown as a viable route for the production of
nanostructured thin films. By using SCBD and by exploiting aerodynamical
effects typical of supersonic beams it is possible to obtain very high
deposition rates with a control on neutral cluster mass distribution, allowing
the deposition of thin films with tailored nanostructure. Due to high
deposition rates, high lateral resolution, low temperature processing, SCBD can
be used for the integration of cluster-assembled films on micro- and
nanofabricated platforms with limited or no post-growth processing. Here we
present the industrial opportunities for batch fabrication of gas sensor
microarrays based on transition metal oxide nanoparticles deposited on
microfabricated substrates.


title: Dispersion Impact on Ballistic CNTFET n+-i-n+ Performances

abstract:
  The designs integrating the promising carbon nanotube transistors (CNTFET)
will have to take into account the constraints implied by the strong dispersion
inherent to nanotube manufacturing. This paper proposes to characterize the
main CNTFET performances : on-current Ion, Ion/Ioff ratio and inverse
sub-threshold slope S according to the dispersion on the nanotube diameter. For
this purpose, we use a compact model suitable for testing several diameter
values.


title: Growth Mechanism and Selective Synthesis of SWNTs

abstract:
  Ever since the landmark discovery of single-walled carbon nanotubes (SWNTs)
in 1993, they have been considered as ideal materials for any kind of
application based on their outstanding properties (e.g. mechanical strength,
thermal conductivity, ultra stability, etc.), and various techniques, including
laser furnace technique, arc discharge technique, and recently, Catalytic
Chemical Vapor Deposition (CCVD) technique, have been developed for the
high-quality macroscopic generation. Recently Hata et al. realized the
macroscopic production after great efforts of many scientists ; however, the
growth mechanisms are still unclear and this incomplete knowledge prevents us
from applying SWNTs to any fields. Here we can partially control the diameter
distribution of SWNTs using Alcohol Catalytic CVD (ACCVD) technique and well
combined catalysts. Their diameter is quite depend on the size of catalyst and
their species, that is why this can be a technique to control SWNTs, and
finally we propose the simple growth model.


title:
Numerical Simulation of The Mechanical Properties of Carbon Nanotube
  Using the Atomistic-Continuum Mechanics

abstract:
  This paper the utilizes atomistic-continuum mechanics (ACM) to investigate
the mechanical properties of single-walled carbon nanotubes (SWCNTs). By
establishing a linkage between structural mechanics and molecular mechanics,
not only the Young's moduli could be obtained but also the modal analysis could
be achieved. In addition, according to atomistic-continuum mechanics and finite
element method, an effective atomistic-continuum model is constructed to
investigate the above two mechanical properties of SWCNTs with affordable
computational time by personal computers. The validity of the results is
demonstrated by comparing them with existing results.


title:
Optical Characterisation of MOVPE Grown Vertically Correlated InAs/GaAs
  Quantum Dots

abstract:
  Structures with self-organised InAs quantum dots in a GaAs matrix were grown
by the low pressure metal-organic vapour phase epitaxy (LP-MOVPE) technique.
Photoluminescence in combination with photomodulated reflectance spectroscopy
were used as the main characterisation methods for the growth optimisation.
Results show that photoreflectance spectroscopy is an excellent tool for
characterisation of QD structures wetting layers (thickness and composition)
and for identification of spacers in vertically stacked QDs structures.


title: The Chiral Model of Sakai-Sugimoto at Finite Baryon Density

abstract:
  In the context of holographic QCD we analyze Sakai-Sugimoto's chiral model at
finite baryon density and zero temperature. The baryon number density is
introduced through compact D4 wrapping S^4 at the tip of D8-\bar{D8}. Each
baryon acts as a chiral point-like source distributed uniformly over R^3, and
leads a non-vanishing U(1)_V potential on the brane. For fixed baryon charge
density n_B we analyze the bulk energy density and pressure using the canonical
formalism. The baryonic matter with point like sources is always in the
spontaneously broken phase of chiral symmetry, whatever the density. The
point-like nature of the sources and large N_c cause the matter to be repulsive
as all baryon interactions are omega mediated. Through the induced DBI action
on D8-\bar{D8}, we study the effects of the fixed baryon charge density n_B on
the pion and vector meson masses and couplings. Issues related to vector
dominance in matter in the context of holographic QCD are also discussed.


title: A note on the lambda-structure on the Burnside ring

abstract:
  Let G be a finite group and let S be a G-set. The Burnside ring of G has a
natural structure of a lambda-ring. However, a priori the images of S under the
lambda-operations can only be computed implicitly. In this paper we establish
an explicit formula, expressing these images as linear combinations of classes
of G-sets.


title: The Schwinger mechanism and graphene

abstract:
  The Schwinger mechanism, the production of charged particle-antiparticle
pairs in a macroscopic external electric field, is derived for 2+1 dimensional
theories. The rate of pair production per unit area for four species of
massless fermions, with charge $q$, in a constant electric field $E$ is given
by $ \pi^{-2} \hbar^{-3/2} \tilde{c}^{-1/2} (q E)^{3/2} $ where $\tilde{c}$ is
the speed of light for the two-dimensional system. To the extent undoped
graphene behaves like the quantum field-theoretic vacuum for massless fermions
in 2+1 dimensions, the Schwinger mechanism should be testable experimentally. A
possible experimental configuration for this is proposed. Effects due to
deviations from this idealized picture of graphene are briefly considered. It
is argued that with present day samples of graphene, tests of the Schwinger
formula may be possible.


title:
Operational definition of (brane induced) space-time and constraints on
  the fundamental parameters

abstract:
  First we contemplate the operational definition of space-time in four
dimensions in light of basic principles of quantum mechanics and general
relativity and consider some of its phenomenological consequences. The quantum
gravitational fluctuations of the background metric that comes through the
operational definition of space-time are controlled by the Planck scale and are
therefore strongly suppressed. Then we extend our analysis to the braneworld
setup with low fundamental scale of gravity. It is observed that in this case
the quantum gravitational fluctuations on the brane may become unacceptably
large. The magnification of fluctuations is not linked directly to the low
quantum gravity scale but rather to the higher-dimensional modification of
Newton's inverse square law at relatively large distances. For models with
compact extra dimensions the shape modulus of extra space can be used as a most
natural and safe stabilization mechanism against these fluctuations.


title:
Waveguide properties of single subwavelength holes demonstrated with
  radially and azimuthally polarized light

abstract:
  We investigate the transmission of focused beams through single subwavelength
holes in a silver film. We use radially and azimuthally polarized light,
respectively, to excite higher order waveguide modes as well as to match the
radial symmetry of the aperture geometry. Remarkably, the transmission
properties can be described by a classical waveguide model even for thicknesses
of the silver film as thin as a quarter of a wavelength.


title: The Status of the Polarized Parton Densities

abstract:
  A survey is given on the present knowledge of the polarized parton
distribution functions. We give an outlook for further developments desired
both on the theoretical as well on the experimental side to complete the
understanding of the spin--structure of nucleons in the future.


title: Prediction for new magnetoelectric fluorides

abstract:
  We use symmetry considerations in order to predict new magnetoelectric
fluorides. In addition to these magnetoelectric properties, we discuss among
these fluorides the ones susceptible to present multiferroic properties. We
emphasize that several materials present ferromagnetic properties. This
ferromagnetism should enhance the interplay between magnetic and dielectric
properties in these materials.


title: Mott transition in anharmonic confinement

abstract:
  Two effects are identified that affect the visibility of the Mott transition
in an atomic gas in an optical lattice confined in a power-law potential. The
transition can be made more pronounced by increasing the power law, but at the
same time, experimental uncertainty in the number of particles will induce
corresponding fluctuations in the measured condensate fraction. Calculations in
two dimensions indicate that a potential slightly more flat-bottomed than a
quadratic one is to be preferred for a wide range of particle number
fluctuation size.


title:
Angular momentum transport by internal gravity waves III - Wave
  excitation by core convection and the Coriolis effect

abstract:
  This is the third in a series of papers that deal with angular momentum
transport by internal gravity waves. We concentrate on the waves excited by
core convection in a 3Msun, Pop I main sequence star. Here, we want to examine
the role of the Coriolis acceleration in the equations of motion that describe
the behavior of waves and to evaluate its impact on angular momentum transport.
We use the so-called traditional approximation of geophysics, which allows
variable separation in radial and horizontal components. In the presence of
rotation, the horizontal structure is described by Hough functions instead of
spherical harmonics. The Coriolis acceleration has two main effects on waves.
It transforms pure gravity waves into gravito-inertial waves that have a larger
amplitude closer to the equator, and it introduces new waves whose restoring
force is mainly the conservation of vorticity. Taking the Coriolis acceleration
into account changes the subtle balance between prograde and retrograde waves
in non-rotating stars. It also introduces new types of waves that are either
purely prograde or retrograde. We show in this paper where the local deposition
of angular momentum by such waves is important.


title: Exclusive rho^0 production in deep inelastic scattering at HERA

abstract:
  Exclusive rho^0 electroproduction at HERA has been studied with the ZEUS
detector using 120 pb^{-1} of integrated luminosity collected during 1996-2000.
The analysis was carried out in the kinematic range of photon virtuality 2 <
Q^2 < 160 GeV$^2, and gamma^* p centre-of-mass energy 32 < W < 180 GeV. The
results include the Q^2 and W dependence of the gamma^* p --> rho^0 p cross
section and the distribution of the squared-four-momentum transfer to the
proton. The helicity analysis of the decay-matrix elements of the rho^0 was
used to study the ratio of the gamma^* p cross section for longitudinal and
transverse photon as a function of Q^2 and W. Finally, an effective Pomeron
trajectory was extracted. The results are compared to various theoretical
predictions.


title: The rotation of very low-mass stars and brown dwarfs

abstract:
  The evolution of angular momentum is a key to our understanding of star
formation and stellar evolution. The rotational evolution of solar-mass stars
is mostly controlled by magnetic interaction with the circumstellar disc and
angular momentum loss through stellar winds. Major differences in the internal
structure of very low-mass stars and brown dwarfs -- they are believed to be
fully convective throughout their lives, and thus should not operate a
solar-type dynamo -- may lead to major differences in the rotation and activity
of these objects. Here, we report on observational studies to understand the
rotational evolution of the very low-mass stars and brown dwarfs.


title: Valid formulas, games and network protocols

abstract:
  We describe a remarkable relation between the notion of valid formula of
predicate logic and the specification of network protocols. We give several
examples such as the acknowledgement of one packet or of a sequence of packets.
We show how to specify the composition of protocols.


title:
Stanley Decompositions, Pretty Clean Filtrations and Reductions Modulo
  Regular Elements

abstract:
  We study the behavior of Stanley decompositions and of pretty clean
filtrations under reduction modulo a regular element.


title: f(R) Gravity: From the Pioneer Anomaly to the Cosmic Acceleration

abstract:
  We use metric formalism in $f(R)$ modified gravity to study the dynamics of
various systems from the solar system to the cosmological scale. we assume an
ansatz for the derivative of action as a function of distance and describe the
Pioneer anomaly and the flat rotation curve of the spiral galaxies. Having the
asymptotic behavior of action, we propose the action of $f(R) = (R + \Lambda)(1
+ \ln(R/R_c)/(R/R_0 + 2/\alpha))$ where in galactic and solar system scales it
can recover our desired form. The vacuum solution of this action also results
in a positive late time acceleration for the universe. We fix the parameters of
this model, comparing with the Pioneer anomaly, rotation curve of spiral
galaxies and Supernova Type Ia gold sample data.


title: Memory in the system: trajectory-environment

abstract:
  In the paper the memory effect in the system consisting from a trajectory of
process and an environment is considered. The environment is presented by
scalar potential and noise. The evolution of system is interpreted as process
of the continuous "measurement" of a trajectory by an environment and\or on the
contrary. In this sense the measured value is entropy-the information about
embedding of the trajectory into configurations space. The concepts
"measurement" and "interaction" are identified alike in quantum theory. Thus,
the entropy evolution is not only the effect of dynamics, but also its cause,
if it is possible to speak about causality in this case. It is shown, that such
non-elastic interaction leads to occurrence of memory in the system. The reflex
memory mechanism is realized as a real conformal dynamic metrics. The
metastable event (attractor) is defined and time of its life is estimated. It
is shown, that in the system there is a change of dynamic modes from spatial
localization to random walk (fluctuation, relaxation). On scale of the
attractors dynamics the memory is appearing as a semi-regular (in some
information sense) drift of the image of fluctuations in a power spectrum of
environment to absolute minimum. The latter properties (topological
convergence) attract the attention to algorithmic aspect of a considered
system.


title: A quantum dot implementation of the quantum NAND algorithm

abstract:
  We propose a physical implementation of the quantum NAND tree evaluation
algorithm. Our approach, based on continuous time quantum walks, uses the wave
interference of a single electron in a heirarchical set of tunnel coupled
quantum dots. We find that the query complexity of the NAND tree evaluation
does not suffer strongly from disorder and dephasing, nor is it directly
limited by temperature or restricted dimensionality for 2-d structures.
Finally, we suggest a potential application of this algorithm to the efficient
determination of high-order correlation functions of complex quantum systems.


title: Pathwise coordinate optimization

abstract:
  We consider ``one-at-a-time'' coordinate-wise descent algorithms for a class
of convex optimization problems. An algorithm of this kind has been proposed
for the $L_1$-penalized regression (lasso) in the literature, but it seems to
have been largely ignored. Indeed, it seems that coordinate-wise algorithms are
not often used in convex optimization. We show that this algorithm is very
competitive with the well-known LARS (or homotopy) procedure in large lasso
problems, and that it can be applied to related methods such as the garotte and
elastic net. It turns out that coordinate-wise descent does not work in the
``fused lasso,'' however, so we derive a generalized algorithm that yields the
solution in much less time that a standard convex optimizer. Finally, we
generalize the procedure to the two-dimensional fused lasso, and demonstrate
its performance on some image smoothing problems.


title: The low energy spectrum of finite size metallic SWNTs

abstract:
  The electronic spectrum of metallic finite-size single-wall carbon nanotubes
at low energies is derived. It is based on a tight-binding description for the
interacting p_{z} electrons. Not only the forward scattering parts of the
Coulomb interaction, which are diagonalized by bosonization, are considered,
but also all other processes becoming relevant for small diameter tubes. As a
consequence of the substructure of the underlying lattice, a spin 1 triplet is
found as ground state if the exchange splitting is larger than the branch
mismatch, a spin 0 singlet otherwise. Moreover the excitation spectrum is
calculated.


title: Quasisymmetric and unipotent tensor categories

abstract:
  We classify braided tensor categories over C of exponential growth which are
quasisymmetric, i.e., the squared braiding is the identity on the product of
any two simple objects. This generalizes the classification results of Deligne
on symmetric categories of exponential growth, and of Drinfeld on
quasitriangular quasi-Hopf algebras. In particular, we classify braided
categories of exponential growth which are unipotent, i.e., those whose only
simple object is the unit object. We also classify fiber functors on such
categories. Finally, using the Etingof-Kazhdan quantization theory of Poisson
algebraic groups, we give a classification of coconnected Hopf algebras, i.e.
of unipotent categories of exponential growth with a fiber functor.


title:
Charmonium and open charm production in nuclear collisions at SPS/FAIR
  energies and the possible influence of a hot hadronic medium

abstract:
  We provide predictions for charmonium and open charm production in nuclear
collisions at SPS/FAIR energies within the framework of the statistical
hadronization model. The increasing importance at lower energies of Lambda_c
production is demonstrated and provides a challenge for future experiments. We
also demonstrate that, because of the large charm quark mass and the different
timescales for charm quark and charmed hadron production, possible
modifications of charmed hadrons in the hot hadronic medium do not lead to
measurable changes in cross sections for D-meson production. A possible
influence of medium effects can be seen, however, in yields of charmonium.
These effects are visible at all energies and results are presented for the
energy range between charm threshold and RHIC energy.


title: Principle of Minimal Energy in Relativistic Schroedinger Theory

abstract:
  The Hamilton-Lagrange action principle for Relativistic Schr\"odinger Theory
(RST) is converted to a variational principle (with constraints) for the
stationary bound states. The groundstate energy is the minimally possible value
of the corresponding energy functional and the relativistic energy eigenvalue
equations do appear as the corresponding variational equations. The matter part
of these eigenvalue equations is a relativistic generalization of the
well-known Ritz principle in non-relativistic quantum mechanics which however
disregards the dynamical character of the particle interactions. If the latter
are included in the proposed principle of minimal energy for the bound states,
one obtains a closed dynamical system for both matter and gauge fields. The new
variational principle enables the development of variational techniques for
solving approximately the energy eigenvalue equations. As a demonstration, the
positronium groundstate is treated in great detail. Here a simple exponential
trial function is sufficient in order to reproduce the (exact) result of
conventional quantum mechanics where the relativistic and spin effects are
neglected.


title: Nonequilibrium Opinion Spreading on 2D Small-World Networks

abstract:
  Irreversible opinion spreading phenomena are studied on small-world networks
generated from 2D regular lattices by means of the magnetic Eden model, a
nonequilibrium kinetic model for the growth of binary mixtures in contact with
a thermal bath. In this model, the opinion or decision of an individual is
affected by those of their acquaintances, but opinion changes (analogous to
spin flips in an Ising-like model) are not allowed. Particularly, we focus on
aspects inherent to the underlying 2D nature of the substrate, such as domain
growth and cluster size distributions. Larger shortcut fractions are observed
to favor long-range ordering connections between distant clusters across the
network, while the temperature is shown to drive the system across an
order-disorder transition, in agreement with previous investigations on related
equilibrium spin systems. Furthermore, the extrapolated phase diagram, as well
as the correlation length critical exponent, are determined by means of
standard finite-size scaling procedures.

categories: physics.soc-ph cond-mat.dis-nn cond-mat.stat-mech physics.comp-ph


title: On perfect, amicable, and sociable chains

abstract:
  Let $x = (x_0,...,x_{n-1})$ be an n-chain, i.e., an n-tuple of non-negative
integers $< n$. Consider the operator $s: x \mapsto x' = (x'_0,...,x'_{n-1})$,
where x'_j represents the number of $j$'s appearing among the components of x.
An n-chain x is said to be perfect if $s(x) = x$. For example, (2,1,2,0,0) is a
perfect 5-chain. Analogously to the theory of perfect, amicable, and sociable
numbers, one can define from the operator s the concepts of amicable pair and
sociable group of chains. In this paper we give an exhaustive list of all the
perfect, amicable, and sociable chains.


title: Observed Properties of Dark Matter on Small Spatial Scales

abstract:
  The nature of dark matter is one of the outstanding questions of
astrophysics. The internal motions of member stars reveal that the lowest
luminosity galaxies in the Local Group are the most dark-matter dominated. New
large datasets allow one to go further, and determine systematic properties of
their dark matter haloes. We summarise recent results, emphasising the critical
role of the dwarf spheroidal galaxies in understanding both dark matter and
baryonic processes that shape galaxy evolution.


title: From chiral vibration to static chirality in ^{135}Nd

abstract:
  Electromagnetic transition probabilities have been measured for the intra-
and inter-band transitions in the two sequences in the nucleus ^{135}Nd that
were previously identified as a composite chiral pair of rotational bands. The
measurements are in good agreement with results of a new combination of TAC and
RPA calculations. The chiral character of the bands is affirmed and it is shown
that their behavior is associated with a transition from a vibrational into a
static chiral regime.


title: A new non-perturbative time-dependent string configuration

abstract:
  A time-dependent bosonic string configuration is discussed, in graviton and
dilaton backgrounds, leading to Weyl-symmetry beta-functions which are
homogeneous in X^0, to any order in alpha'. As a consequence, a string
reparametrization can always be implemented, such that beta functions can be
cancelled, to any order in alpha'. This non-perturbative conformal invariance
is valid for any target space dimension, and leads to a power law expanding
Universe, for which the power vanishes if a specific relation between the
dimension and dilaton amplitude holds. Finally, D=4 is the minimum dimension
(in the case of a spherical world sheet) for which this configuration is
consistent with a Wick rotation in a Minkowski target space.


title:
Preliminary Results from MINOS on Muon Neutrino Disappearance Based on
  an Exposure of 2.5x10^20 120 GeV Protons on the NuMI Target

abstract:
  Updating our previous measurements with new data and analysis modifications,
we report preliminary results on the energy-dependent deficit of muon neutrinos
from the Fermilab NuMI beam as observed with the MINOS Far Detector located 735
km away in the Soudan Underground Laboratory. From an exposure of 2.50x10^20
protons on target, we observe 563 charged-current nu_mu interaction candidates
in the Far Detector, where 738+/-30 events are expected in the absence of
neutrino oscillations. We have analyzed these data assuming two-flavor nu_mu to
nu_tau oscillations. From a simultaneous fit to the reconstructed nu_mu energy
spectra obtained during two running periods we obtain the neutrino squared-mass
difference Delta m_{32}^2 = (2.38 +0.20/-0.16) x 10^-3 eV^2/c^4 with errors at
68% confidence level (CL), and mixing angle sin^2(2 theta_23) > 0.84 at 90% CL.
The uncertainties and confidence intervals include both statistical and
systematic errors. All results and plots presented here are preliminary.


title: A Light-Based Device for Solving the Hamiltonian Path Problem

abstract:
  In this paper we suggest the use of light for performing useful computations.
Namely, we propose a special device which uses light rays for solving the
Hamiltonian path problem on a directed graph. The device has a graph-like
representation and the light is traversing it following the routes given by the
connections between nodes. In each node the rays are uniquely marked so that
they can be easily identified. At the destination node we will search only for
particular rays that have passed only once through each node. We show that the
proposed device can solve small and medium instances of the problem in
reasonable time.


title: Information Rate Loss due to Radiation Decoherence

abstract:
  The information rates achievable by using electromagnetic radiation affected
by thermal noise and signal decoherence are studied. The standard coherent
Gaussian model is compared with an alternative photon gas model which
represents lack of a shared phase reference between transmitter and receiver.
At any frequency, information rates over the photon gas model essentially
coincide with those over the Gaussian model when the signal-to-noise ratio is
below a threshold. Only above the threshold does decoherence cause a loss in
information rates; the loss can amount to half of the capacity. The threshold
exceeds 40 dB for radio frequencies and vanishes at optical frequencies.


title: Optimizing Optical Quantum Logic Gates using Genetic Algorithms

abstract:
  We introduce the method of using an annealing genetic algorithm to the
numerically complex problem of looking for quantum logic gates which
simultaneously have highest fidelity and highest success probability. We first
use the linear optical quantum nonlinear sign (NS) gate as an example to
illustrate the efficiency of this method. We show that by appropriately
choosing the annealing parameters, we can reach the theoretical maximum success
probability (1/4 for NS) for each attempt. We then examine the controlled-z
(CZ) gate as the first new problem to be solved. We show results that agree
with the highest known maximum success probability for a CZ gate (2/27) while
maintaining a fidelity of 0.9997. Since the purpose of our algorithm is to
optimize a unitary matrix for quantum transformations, it could easily be
applied to other areas of interest such as quantum optics and quantum sensors.


title:
Transport processes in stars: diffusion, rotation, magnetic fields and
  internal waves

abstract:
  In this paper, I explore various transport processes that have a large impact
of the distribution of elements inside stars and thus, on stellar evolution. A
heuristic description of the physics behind equations is provided, and key
references are given. Finally, for each process, I will briefly review (some)
important results as well as discuss directions for future work.


title:
The reverse engineering problem with probabilities and sequential
  behavior: Probabilistic Sequential Networks

abstract:
  The reverse engineering problem with probabilities and sequential behavior is
introducing here, using the expression of an algorithm. The solution is
partially founded, because we solve the problem only if we have a Probabilistic
Sequential Network. Therefore the probabilistic structure on sequential
dynamical systems is introduced here, the new model will be called
Probabilistic Sequential Network, PSN. The morphisms of Probabilistic
Sequential Networks are defined using two algebraic conditions, whose imply
that the distribution of probabilities in the systems are close. It is proved
here that two homomorphic Probabilistic Sequential Networks have the same
equilibrium or steady state probabilities. Additionally, the proof of the set
of PSN with its morphisms form the category PSN, having the category of
sequential dynamical systems SDS, as a full subcategory is given. Several
examples of morphisms, subsystems and simulations are given.


title: Sch'nol's Theorem For Strongly Local Forms

abstract:
  We prove a variant of Sch'nol's theorem in a general setting: for generators
of strongly local Dirichlet forms perturbed by measures. As an application, we
discuss quantum graphs with $\delta$- or Kirchhoff boundary conditions.


title: The string/gauge theory correspondence in QCD

abstract:
  Ideas about a duality between gauge fields and strings have been around for
many decades. During the last ten years, these ideas have taken a much more
concrete mathematical form. String descriptions of the strongly coupled
dynamics of semi-realistic gauge theories, exhibiting confinement and chiral
symmetry breaking, are now available. These provide remarkably simple ways to
compute properties of the strongly coupled quark-gluon fluid phase, and also
shed new light on various phenomenological models of hadron fragmentation. We
present a review and highlight some exciting recent developments.


title: Defensive forecasting for optimal prediction with expert advice

abstract:
  The method of defensive forecasting is applied to the problem of prediction
with expert advice for binary outcomes. It turns out that defensive forecasting
is not only competitive with the Aggregating Algorithm but also handles the
case of "second-guessing" experts, whose advice depends on the learner's
prediction; this paper assumes that the dependence on the learner's prediction
is continuous.


title:
Theoretical study of a localized quantum spin reversal by the sequential
  injection of spins in a spin quantum dot

abstract:
  This is a theoretical study of the reversal of a localized quantum spin
induced by sequential injection of spins for a spin quantum dot that has a
quantum spin. The system consists of ``electrode/quantum
well(QW)/dot/QW/electrode" junctions, in which the left QW has an energy level
of conduction electrons with only up-spin. We consider a situation in which
up-spin electrons are sequentially injected from the left electrode into the
dot through the QW and an exchange interaction acts between the electrons and
the localized spin. To describe the sequentially injected electrons, we propose
a simple method based on approximate solutions from the time-dependent
Schr$\ddot{\rm o}$dinger equation. Using this method, it is shown that the spin
reversal occurs when the right QW has energy levels of conduction electrons
with only down-spin. In particular, the expression of the reversal time of a
localized spin is derived and the upper and lower limits of the time are
clearly expressed. This expression is expected to be useful for a rough
estimation of the minimum relaxation time of the localized spin to achieve the
reversal. We also obtain analytic expressions for the expectation value of the
localized spin and the electrical current as a function of time. In addition,
we found that a system with the non-magnetic right QW exhibits spin reversal or
non-reversal depending on the exchange interaction.


title: How much is a quantum controller controlled by the controlled system?

abstract:
  We consider unitary transformations on a bipartite system A x B. To what
extent entails the ability to transmit information from A to B the ability to
transfer information in the converse direction? We prove a dimension-dependent
lower bound on the classical channel capacity C(A<--B) in terms of the capacity
C(A-->B) for the case that the bipartite unitary operation consists of
controlled local unitaries on B conditioned on basis states on A. This can be
interpreted as a statement on the strength of the inevitable backaction of a
quantum system on its controller.
  If the local operations are given by the regular representation of a finite
group G we have C(A-->B)=log |G| and C(A<--B)=log N where N is the sum over the
degrees of all inequivalent representations. Hence the information deficit
C(A-->B)-C(A<--B) between the forward and the backward capacity depends on the
"non-abelianness" of the control group. For regular representations, the ratio
between backward and forward capacities cannot be smaller than 1/2. The
symmetric group S_n reaches this bound asymptotically. However, for the general
case (without group structure) all bounds must depend on the dimensions since
it is known that the ratio can tend to zero.


title:
A Soft Interaction Model at Ultra High Energies: Amplitudes, Cross
  Sections and Survival Probabilities

abstract:
  In this paper we present a two channel model with the goal of reproducing the
soft scattering data available in the ISR-Tevatron energy range, and extend the
model results to LHC and Cosmic Rays energies. A characteristic feature of the
model is that we represent the sum of all diffractive final states at a vertex,
by a single diffractive state. Our two main results are: (i) The approach of
the elastic scattering amplitude to the black disc bound is very slow, reaching
it at energies far higher than the GZK ankle cutoff. (ii) Our predicted
survival probability for Higgs exclusive central diffractive production at the
LHC is 0.7%, which is considerably smaller than our previous estimate. The
above features are compatible with a parton-like model in which the traditional
soft Pomeron is replaced by an amplitude describing the partonic system, which
issaturated in the soft (long distance) limit.


title:
Quaternionic and Poisson-Lie structures in 3d gravity: the cosmological
  constant as deformation parameter

abstract:
  Each of the local isometry groups arising in 3d gravity can be viewed as the
group of unit (split) quaternions over a ring which depends on the cosmological
constant. In this paper we explain and prove this statement, and use it as a
unifying framework for studying Poisson structures associated with the local
isometry groups. We show that, in all cases except for Euclidean signature with
positive cosmological constant, the local isometry groups are equipped with the
Poisson-Lie structure of a classical double. We calculate the dressing action
of the factor groups on each other and find, amongst others, a simple and
unified description of the symplectic leaves of SU(2) and SL(2,R). We also
compute the Poisson structure on the dual Poisson-Lie groups of the local
isometry groups and on their Heisenberg doubles; together, they determine the
Poisson structure of the phase space of 3d gravity in the so-called
combinatorial description.


title: Elliptic Flow arising from Ridges due to Semi-hard Scattering

abstract:
  Azimuthal anisotropy in heavy-ion collisions is studied by taking into
account the ridges generated by semi-hard scattering of intermediate-momentum
partons, which can be sensitive to the initial spatial configuration of the
medium in non-central collisions. In a simple treatment of the problem where
the recombination of only thermal partons is considered, analytical formulas
can be derived that yield results in accord with the data on v_2 for p_T <1-2
GeV/c. Centrality dependence is described by a geometrical factor. Ridge
phenomenology is used to determine the initial slopes of v_2 at low p_T for
both pion and proton. For higher p_T, shower partons from high-p_T jets must be
included, but they are not considered here.


title:
X-ray flares, plateaus, and chromatic breaks of GRB afterglows from
  up-scattered forward-shock emission

abstract:
  Scattering of the forward-shock synchrotron emission by a relativistic
outflow located behind the leading blast-wave may produce an X-ray emission
brighter than that coming directly from the forward-shock and may explain four
features displayed by Swift X-ray afterglows: flares, plateaus (slow decays),
chromatic light-curve breaks, and fast post-plateau decays. For a cold
scattering outflow, the reflected flux overshines the primary one if the
scattering outflow is nearly baryon-free and highly relativistic. These two
requirements can be relaxed if the scattering outflow is energized by weak
internal shocks, so that the incident forward-shock photons are also
inverse-Compton scattered, in addition to bulk-scattering. Sweeping-up of the
photons left behind by the forward shock naturally yields short X-ray flares.
Owing to the boost in photon energy produced by bulk-scattering scattering, the
reflected emission is more likely to overshine that coming directly from the
forward shock at higher photon energies, yielding light-curve plateaus and
breaks that appear only in the X-ray. The brightness, shape, and decay of the
X-ray light-curve plateau depend on the radial distribution of the scatterer's
Lorentz factor and mass-flux. Chromatic X-ray light-curve breaks and sharp
post-plateau decays cannot be accommodated by the direct forward-shock emission
and argue in favour of the scattering-outflow model proposed here. On the other
hand, the X-ray afterglows without plateaus, those with achromatic breaks, and
those with very long-lived power-law decays are more naturally accommodated by
the standard forward-shock model. Thus the diversity of X-ray light-curves
arises from the interplay of the scattered and direct forward-shock emissions.


title: Connecting GRBs and galaxies: the probability of chance coincidence

abstract:
  Studies of GRB host galaxies are crucial to understanding GRBs. However,
since they are identified by the superposition in the plane of the sky of a GRB
afterglow and a galaxy there is always a possibility that an association
represents a chance alignment, rather than a physical connection. We examine a
uniform sample of 72 GRB fields to explore the probability of chance
superpositions. There is typically a ~1% chance that an optical afterglow will
coincide with a galaxy by chance. While spurious host galaxy detections will,
therefore, be rare, the possibility must be considered when examining
individual GRB/host galaxy examples. It is also tempting to use the large and
uniform collection of X-ray afterglow positions to search for GRB-associated
galaxies. However, we find that approximately half of the 14 superpositions in
our sample are likely to occur by chance, so in the case of GRBs localized only
by an X-ray afterglow, even statistical studies are suspect.


title:
Simultaneous Multi-Wavelength Observations of Magnetic Activity in
  Ultracool Dwarfs. I. The Complex Behavior of the M8.5 Dwarf TVLM513-46546

abstract:
  [Abridged] We present the first simultaneous radio, X-ray, ultraviolet, and
optical spectroscopic observations of the M8.5 dwarf TVLM513-46546, with a
duration of 9 hours. These observations are part of a program to study the
origin of magnetic activity in ultracool dwarfs, and its impact on
chromospheric and coronal emission. Here we detect steady quiescent radio
emission superposed with multiple short-duration, highly polarized flares;
there is no evidence for periodic bursts previously reported for this object,
indicating their transient nature. We also detect soft X-ray emission, with
L_X/L_bol~10^-4.9, the faintest to date for any object later than M5, and a
possible weak X-ray flare. TVLM513-46546 continues the trend of severe
violation of the radio/X-ray correlation in ultracool dwarfs, by nearly 4
orders of magnitude. From the optical spectroscopy we find that the Balmer line
luminosity exceeds the X-ray luminosity by a factor of a few, suggesting that,
unlike in early M dwarfs, chromospheric heating may not be due to coronal X-ray
emission. More importantly, we detect a sinusoidal H-alpha light curve with a
period of 2 hr, matching the rotation period of TVLM513-46546. This is the
first known example of such Balmer line behavior, which points to a co-rotating
chromospheric hot spot or an extended magnetic structure, with a covering
fraction of about 50%. This feature may be transitory based on the apparent
decline in light curve peak during the four observed maxima. From the radio
data we infer a large scale steady magnetic field of ~100 G, in good agreement
with the value required for confinement of the X-ray emitting plasma. The radio
flares, on the other hand, are produced in a component of the field with a
strength of ~3 kG and a likely multi-polar configuration.


title: Solving the Hamiltonian path problem with a light-based computer

abstract:
  In this paper we propose a special computational device which uses light rays
for solving the Hamiltonian path problem on a directed graph. The device has a
graph-like representation and the light is traversing it by following the
routes given by the connections between nodes. In each node the rays are
uniquely marked so that they can be easily identified. At the destination node
we will search only for particular rays that have passed only once through each
node. We show that the proposed device can solve small and medium instances of
the problem in reasonable time.


title: Low Resolution Spectral Templates For Galaxies From 0.2 -- 10 microns

abstract:
  We built an optimal basis of low resolution templates for galaxies over the
wavelength range from 0.2 to 10 $\mu$m using a variant of the algorithm
presented by Budavari et al. (2000). We derived them using eleven bands of
photometry from the NDWFS, FLAMEX, zBo\"otes and IRAC Shallow surveys for 16033
galaxies in the NDWFS Bo\"otes field with spectroscopic redshifts measured by
the AGN and Galaxy Evolution Survey. We also developed algorithms to accurately
determine photometric redshifts, K corrections and bolometric luminosities
using these templates. Our photometric redshifts have an accuracy of
$\sigma_z/(1+z) = 0.04$ when clipped to the best 95%. We used these templates
to study the spectral type distribution in the field and to estimate luminosity
functions of galaxies as a function of redshift and spectral type. In
particular, we note that the 5-8$\mu$m color distribution of galaxies is
bimodal, much like the optical g--r colors.


title: UCD Candidates in the Hydra Cluster

abstract:
  NGC 3311, the giant cD galaxy in the Hydra cluster (A1060), has one of the
largest globular cluster systems known. We describe new Gemini GMOS (g',i')
photometry of the NGC 3311 field which reveals that the red, metal-rich side of
its globular cluster population extends smoothly upward into the mass range
associated with the new class of Ultra-Compact Dwarfs (UCDs). We identify 29
UCD candidates with estimated masses > 6x10^6 solar masses and discuss their
characteristics. This UCD-like sequence is the most well defined one yet seen,
and reinforces current ideas that the high-mass end of the globular cluster
sequence merges continuously into the UCD sequence, which connects in turn to
the E galaxy structural sequence.


title:
Supernova Remnants in the Large Magellanic Clouds IX: Multiwavelength
  Analysis of the Physical Structure of N49

abstract:
  We present a multiwavelength analysis of the supernova remnant N49 in the
Large Magellanic Cloud. Using high-resolution Hubble Space Telescope WFPC2
images of H-alpha, [S II] and [O III] emission, we study the morphology of the
remnant and calculate the rms electron densities in different regions. We
detect an offset of [O III] and H-alpha emission of about 0.5 arcsec, and
discuss possible scenarios that could give rise to such high values. The
kinematics of the remnant is analyzed by matching individual filaments to the
echelle spectra obtained at CTIO. We detect narrow H-alpha emission component
which we identify as the diffuse post-shock recombination radiation, and
discrete broad emission features that correspond to the shocked gas in
filaments. The overall expansion of the remnant is about 250 km/s. The dense
clouds are shocked up to line-of-sight velocities of 250 km/s and the less
dense gas up to 300 km/s. A few cloudlets have even higher radial velocities,
reaching up to 350 km/s. We confirm the presence of the cavity in the remnant,
and identify the center of explosion. Using archival Chandra and XMM-Newton
data, we observe the same trends in surface brightness distribution for the
optical and X-ray images. We carry out the spectral analysis of three regions
that represent the most significant optical features.


title:
Spectral evolution of non-thermal electron distributions in intense
  radiation fields

abstract:
  (abridged) Models of many astrophysical gamma-ray sources assume they contain
a homogeneous distribution of electrons that are injected as a power-law in
energy and evolve by interacting with radiation fields, magnetic fields and
particles in the source and by escaping. This problem is particularly
complicated if the radiation fields have higher energy density than the
magnetic field and are sufficiently energetic that inverse Compton scattering
is not limited to the Thomson regime. We present a simple, time-dependent,
semi-analytical solution of the electron kinetic equation that treats both
continuous and impulsive injection, cooling via synchrotron and inverse Compton
radiation, (taking into account Klein-Nishina effects) and energy dependent
particle escape. The kinetic equation for an arbitrary, time-dependent source
function is solved by the method of Laplace transformations. Using an
approximate expression for the energy loss rate that takes into account
synchrotron and inverse Compton losses including Klein-Nishina effects for
scattering off an isotropic photon field with either a power-law or black-body
distribution, we find explicit expressions for the cooling time and escape
probability of individual electrons. This enables the full, time-dependent
solution to be reduced to a single quadrature. From the electron distribution,
we then construct the time-dependent, multi-wavelength emission spectrum. We
compare our solutions with several limiting cases and discuss the general
appearance and temporal behaviour of spectral features (i.e., cooling breaks,
bumps etc.). As a specific example, we model the broad-band energy spectrum of
the open stellar association Westerlund-2 at different times of its evolution,
and compare it with observations.


title:
The galaxy power spectrum: precision cosmology from large scale
  structure?

abstract:
  Published galaxy power spectra from the 2dFGRS and SDSS are not in good
agreement. We revisit this issue by analyzing both the 2dFGRS and SDSS DR5
catalogues using essentially identical techniques. We confirm that the 2dFGRS
exhibits relatively more large scale power than the SDSS, or, equivalently,
SDSS has more small scale power. We demonstrate that this difference is due to
the r-band selected SDSS catalogue being dominated by more strongly clustered
red galaxies, which have a stronger scale dependent bias. The power spectra of
galaxies of the same rest frame colours from the two surveys match well. If not
accounted for, the difference between the SDSS and 2dFGRS power spectra causes
a bias in the obtained constraints on cosmological parameters which is larger
than the uncertainty with which they are determined. We also found that the
correction developed by Cole et al.(2005) to model the distortion in the shape
of the power spectrum due to non-linear evolution and scale dependent bias is
not able to reconcile the constraints obtained from the 2dFGRS and SDSS power
spectra. Intriguingly, the model is able to describe the differences between
the 2dFGRS and the much more strongly clustered LRG sample, which exhibits
greater nonlinearities. This shows that more work is needed to understand the
relation between the galaxy power spectrum and the linear perturbation theory
prediction for the power spectrum of matter fluctuations. It is therefore
important to accurately model these effects to get precise estimates of
cosmological parameters from these power spectra and from future galaxy surveys
like Pan-STARRS, or the Dark Energy Survey, which will use selection criteria
similar to the one of SDSS.


title:
Cluster Structure in Cosmological Simulations I: Correlation to
  Observables, Mass Estimates, and Evolution

abstract:
  We use Enzo, a hybrid Eulerian AMR/N-body code including non-gravitational
heating and cooling, to explore the morphology of the X-ray gas in clusters of
galaxies and its evolution in current generation cosmological simulations. We
employ and compare two observationally motivated structure measures: power
ratios and centroid shift. Overall, the structure of our simulated clusters
compares remarkably well to low-redshift observations, although some
differences remain that may point to incomplete gas physics. We find no
dependence on cluster structure in the mass-observable scaling relations, T_X-M
and Y_X-M, when using the true cluster masses. However, estimates of the total
mass based on the assumption of hydrostatic equilibrium, as assumed in
observational studies, are systematically low. We show that the hydrostatic
mass bias strongly correlates with cluster structure and, more weakly, with
cluster mass. When the hydrostatic masses are used, the mass-observable scaling
relations and gas mass fractions depend significantly on cluster morphology,
and the true relations are not recovered even if the most relaxed clusters are
used. We show that cluster structure, via the power ratios, can be used to
effectively correct the hydrostatic mass estimates and mass-scaling relations,
suggesting that we can calibrate for this systematic effect in cosmological
studies. Similar to observational studies, we find that cluster structure,
particularly centroid shift, evolves with redshift. This evolution is mild but
will lead to additional errors at high redshift. Projection along the line of
sight leads to significant uncertainty in the structure of individual clusters:
less than 50% of clusters which appear relaxed in projection based on our
structure measures are truly relaxed.


title: Classical Theory of Optical Nonlinearity in Conducting Nanoparticles

abstract:
  We develop a classical theory of electron confinement in conducting
nanoparticles. The theory is used to compute the nonlinear optical response of
the nanoparticle to a harmonic external field.


title:
Coulomb blockade in a Si channel gated by an Al single-electron
  transistor

abstract:
  We incorporate an Al-AlO_x-Al single-electron transistor as the gate of a
narrow (~100 nm) metal-oxide-semiconductor field-effect transistor (MOSFET).
Near the MOSFET channel conductance threshold, we observe oscillations in the
conductance associated with Coulomb blockade in the channel, revealing the
formation of a Si single-electron transistor. Abrupt steps present in sweeps of
the Al transistor conductance versus gate voltage are correlated with
single-electron charging events in the Si transistor, and vice versa. Analysis
of these correlations using a simple electrostatic model demonstrates that the
two single-electron transistor islands are closely aligned, with an
inter-island capacitance approximately equal to 1/3 of the total capacitance of
the Si transistor island, indicating that the Si transistor is strongly coupled
to the Al transistor.


title:
Spectroscopy of horizontal branch stars in NGC6752 - Anomalous results
  on atmospheric parameters and masses

abstract:
  We used the ESO VLT-FORS2 facility to collect low-resolution spectra of 51
targets distributed along the Horizontal Branch. We determined atmospheric
parameters by comparison with theoretical models through standard fitting
routines, and masses by basic equations. Results are in general in good
agreement with previous works, although not always with theoretical
expectations for cooler stars (Teff<15000 K). The calculated color excess is
systematically lower than literature values, pointing towards a possible
underestimation of effective temperatures. Moreover, we find two groups of
stars at Teff=14000 K and at Teff=27000$ K that present anomalies with respect
to the general trend and expectations. We suppose that the three peculiar
bright stars at Teff=14000 K are probably affected by an enhanced stellar wind.
For the eight Extreme Horizontal Branch stars at Teff=27000 K which show
unusually high masses we find no plausible explanation. While most of our
results agree well with the predictions of standard horizontal branch
evolution, we still have problems with the low masses we derive in certain
temperature ranges. We believe that Kurucz ATLAS9 LTE model atmospheres with
solar-scaled abundances are probably inadequate for these temperature ranges.
Concerning the group of anomalous stars at Teff=27000 K, a Kolmogorov-Smirnov
test indicates that there is only an 8.4% probability that these stars are
randomly drawn from the general distribution in the color-magnitude diagram.
This is not conclusive but points out that these stars could be both (and
independently) spectroscopically and photometrically peculiar with respect to
the general Extreme Horizontal Branch population.


title: Electron Thermal Microscopy

abstract:
  The progress of semiconductor electronics toward ever-smaller length scales
and associated higher power densities brings a need for new high-resolution
thermal microscopy techniques. Traditional thermal microscopy is performed by
detecting infrared radiation with far-field optics, where the resolution is
limited by the wavelength of the light. By adopting a serial, local-probe
approach, near-field and scanned-probe microscopies can surpass this limit but
sacrifice imaging speed. In the same way that electron microscopy was invented
to overcome the resolution limits of light microscopy, we here demonstrate a
thermal imaging technique that uses an electron microscope to overcome the
limits of infrared thermal microscopy, without compromising imaging speed. With
this new technique, which we call electron thermal microscopy, temperature is
resolved by detecting the liquid-solid transition of arrays of nanoscale
islands, producing thermal maps in real-time (30 thermal images per second over
a 16um^2 field-of-view). The experimental demonstration is supported by
combined electrical and thermal modeling.