title: Arbiter as the Third Man in classical and quantum games

abstract:
  We study possible influence of not necessarily sincere arbiter on the course
of classical and quantum 2x2 games and we show that this influence in the
quantum case is much bigger than in the classical case. Extreme sensitivity of
quantum games on initial states of quantum objects used as carriers of
information in a game shows that a quantum game, contrary to a classical game,
is not defined by a payoff matrix alone but also by an initial state of objects
used to play a game. Therefore, two quantum games that have the same payoff
matrices but begin with different initial states should be considered as
different games.


title: Triangles with two given integral sides

abstract:
  We study some Diophantine problems related to triangles with two given
integral sides. We solve two problems posed by Zolt\'an Bertalan and we also
provide some generalization.


title: Arithmetic progressions of squares, cubes and $n$-th powers

abstract:
  In this paper we continue the investigations about unlike powers in
arithmetic progression. We provide sharp upper bounds for the length of
primitive non-constant arithmetic progressions consisting of squares/cubes and
$n$-th powers.


title:
Towards an understanding of the Of?p star HD 191612: optical
  spectroscopy

abstract:
  We present extensive optical spectroscopy of the early-type magnetic star HD
191612 (O6.5f?pe-O8fp). The Balmer and HeI lines show strongly variable
emission which is highly reproducible on a well-determined 538-d period. Metal
lines and HeII absorptions (including many selective emission lines but
excluding He II 4686A emission) are essentially constant in line strength, but
are variable in velocity, establishing a double-lined binary orbit with P(orb)
= 1542d, e=0.45. We conduct a model-atmosphere analysis of the primary, and
find that the system is consistent with a O8: giant with a B1: main-sequence
secondary. Since the periodic 538-d changes are unrelated to orbital motion,
rotational modulation of a magnetically constrained plasma is strongly favoured
as the most likely underlying `clock'. An upper limit on the equatorial
rotation is consistent with this hypothesis, but is too weak to provide a
strong constraint.


title:
High resolution spectroscopy of the high velocity hot post-AGB star LS
  III +52 24 (IRAS 22023+5249)

abstract:
  Aims: To investigate the first high resolution optical spectrum of the B-type
star, LS III +52 24, identified as the optical counterpart of the hot post-AGB
candidate IRAS 22023+5249 (I22023).
  Methods: We carried out detailed identifications of the observed absorption
and emission features in the high resolution spectrum (4290 - 9015 A) of I22023
obtained with the Utrecht Echelle Spectrograph on the 4.2m William Herschel
Telescope. Using Kurucz's WIDTH9 program and the spectrum synthesis code,
SYNSPEC, we determined the atmospheric parameters and abundances. The
photospheric abundances were derived under the LTE approximation. The NEBULAR
package under IRAF was used to estimate the electron temperature (T_e) and the
electron density (N_e) from the [N II] and [S II] lines.
  Results: We estimated T_eff=24000 K, log g=3.0, xi_t=7 kms^{-1}. The derived
CNO abundances suggest an evolved star with C/O < 1. P-Cygni profiles of
hydrogen and helium indicate ongoing post-AGB mass loss. The presence of [N II]
and [S II] lines and the non-detection of [O III] indicate that photoionisation
has just started. The derived nebular parameters T_e=7000 K, N_e=1.2X10^{4}
cm^{-3} are comparable to those measured in young, compact planetary nebulae
(PNe). The nebular expansion velocity was estimated to be 17.5 kms^{-1}.
  Conclusions: The observed spectral features, large heliocentric radial
velocity (-148.31 +/- 0.60 kms^{-1}), atmospheric parameters and chemical
composition indicate that I22023, at a distance of 1.95 kpc, is an evolved
post-AGB star belonging to the old disk population. The nebular parameters
suggest that the central star may be evolving into a compact, young PN, similar
to Hen3-1357.


title:
Note on a paper "An Extension of a Theorem of Euler" by Hirata-Kohno et
  al

abstract:
  In this paper we extend a result of Hirata-Kohno, Laishram, Shorey and
Tijdeman on the Diophantine equation $n(n+d)...(n+(k-1)d)=by^2,$ where
$n,d,k\geq 2$ and $y$ are positive integers such that $\gcd(n,d)=1.$


title:
Approximately Einstein ACH metrics, volume renormalization, and an
  invariant for contact manifolds

abstract:
  To any smooth compact manifold $M$ endowed with a contact structure $H$ and
partially integrable almost CR structure $J$, we prove the existence and
uniqueness, modulo high-order error terms and diffeomorphism action, of an
approximately Einstein ACH (asymptotically complex hyperbolic) metric $g$ on
$M\times (-1,0)$.
  We consider the asymptotic expansion, in powers of a special defining
function, of the volume of $M\times (-1,0)$ with respect to $g$ and prove that
the log term coefficient is independent of $J$ (and any choice of contact form
$\theta$), i.e., is an invariant of the contact structure $H$.
  The approximately Einstein ACH metric $g$ is a generalisation of, and
exhibits similar asymptotic boundary behaviour to, Fefferman's approximately
Einstein complete K\"ahler metric $g_+$ on strictly pseudoconvex domains. The
present work demonstrates that the CR-invariant log term coefficient in the
asymptotic volume expansion of $g_+$ is in fact a contact invariant. We discuss
some implications this may have for CR $Q$-curvature.
  The formal power series method of finding $g$ is obstructed at finite order.
We show that part of this obstruction is given as a one-form on $H^*$. This is
a new result peculiar to the partially integrable setting.


title: Discriminant Analysis and Secondary-Beam Charge Recognition

abstract:
  The discriminant-analysis method has been applied to optimize the exotic-beam
charge recognition in a projectile fragmentation experiment. The experiment was
carried out at the GSI using the fragment separator (FRS) to produce and select
the relativistic secondary beams, and the ALADIN setup to measure their
fragmentation products following collisions with Sn target nuclei. The beams of
neutron poor isotopes around 124La and 107Sn were selected to study the isospin
dependence of the limiting temperature of heavy nuclei by comparing with
results for stable 124Sn projectiles. A dedicated detector to measure the
projectile charge upstream of the reaction target was not used, and alternative
methods had to be developed. The presented method, based on the multivariate
discriminant analysis, allowed to increase the efficacy of charge recognition
up to about 90%, which was about 20% more than achieved with the simple scalar
methods.


title:
Origin of the excitonic recombinations in hexagonal boron nitride by
  spatially resolved cathodoluminescence spectroscopy

abstract:
  The excitonic recombinations in hexagonal boron nitride (hBN) are
investigated with spatially resolved cathodoluminescence spectroscopy in the UV
range. Cathodoluminescence images of an individual hBN crystallite reveals that
the 215 nm free excitonic line is quite homogeneously emitted along the
crystallite whereas the 220 nm and 227 nm excitonic emissions are located in
specific regions of the crystallite. Transmission electron microscopy images
show that these regions contain a high density of crystalline defects. This
suggests that both the 220 nm and 227 nm emissions are produced by the
recombination of excitons bound to structural defects.


title:
Does heterosexual transmission drive the HIV/AIDS epidemic in
  Sub-Saharan Africa (or elsewhere)?

abstract:
  A two-sex Basic Reproduction Number (BRN) is used to investigate the
conditions under which the Human Immunodeficiency Virus (HIV) may spread
through heterosexual contacts in Sub-Saharan Africa. (The BRN is the expected
number of new infections generated by one infected individual; the disease
spreads if the BRN is larger than 1). A simple analytical expression for the
BRN is derived on the basis of recent data on survival rates, transmission
probabilities, and levels of sexual activity. Baseline results show that in the
population at large (characterized by equal numbers of men and women) the BRN
is larger than 1 if every year each person has 82 sexual contacts with
different partners. the BRN is also larger than 1 for commercial sex workers
(CSWs) and their clients (two populations of different sizes) if each CSW has
about 256 clients per year and each client visits one CSW every two weeks. A
sensitivity analysis explores the effect on the BRN of a doubling (or a
halving) of the transmission probabilities. Implications and extensions are
discussed.


title: Diffusion in an Expanding Plasma using AdS/CFT

abstract:
  We consider the diffusion of a non-relativistic heavy quark of fixed mass M,
in a one-dimensionally expanding and strongly coupled plasma using the AdS/CFT
duality. The Green's function constructed around a static string embedded in a
background with a moving horizon, is identified with the noise correlation
function in a Langevin approach. The (electric) noise decorrelation is of order
1/T(\tau) while the velocity de-correlation is of order MD(\tau)/T(\tau). For
MD>1, the diffusion regime is segregated and the energy loss is Langevin-like.
The time dependent diffusion constant D(\tau) asymptotes its adiabatic limit
2/\pi\sqrt{\lambda} T(\tau) when \tau/\tau_0=(1/3\eta_0\tau_0)^3 where \eta_0
is the drag coefficient at the initial proper time \tau_0.


title: Limitation of the modulation method to smooth wire guide roughness

abstract:
  It was recently demonstrated that wire guide roughness can be suppressed by
modulating the wire currents so that the atoms experience a time-averaged
potential without roughness. We theoretically study the limitations of this
technique. At low modulation frequency, we show that the longitudinal potential
modulation produces a heating of the cloud and we compute the heating rate. We
also give a quantum derivation of the rough conservative potential associated
with the micro-motion of the atoms. At large modulation frequency, we compute
the loss rate due to non adiabatic spin flip and show it presents resonnances
at multiple modulation frequencies. These studies show that the modulation
technique works for a wide range of experimental parameters. We also give
conditions to realise radio-frequency evaporative cooling in such a modulated
trap.


title:
Covariant Mappings for the Description of Measurement, Dissipation and
  Decoherence in Quantum Mechanics

abstract:
  The general formalism of quantum mechanics for the description of statistical
experiments is briefly reviewed, introducing in particular position and
momentum observables as POVM characterized by their covariance properties with
respect to the isochronous Galilei group. Mappings describing state
transformations both as a consequence of measurement and of dynamical evolution
for a closed or open system are considered with respect to the general
constraints they have to obey and their covariance properties with respect to
symmetry groups. In particular different master equations are analyzed in view
of the related symmetry group, recalling the general structure of mappings
covariant under the same group. This is done for damped harmonic oscillator,
two-level system and quantum Brownian motion. Special attention is devoted to
the general structure of translation-covariant master equations. Within this
framework a recently obtained quantum counterpart of the classical linear
Boltzmann equation is considered, as well as a general theoretical framework
for the description of different decoherence experiments, pointing to a
connection between different possible behaviours in the description of
decoherence and the characteristic functions of classical L\'evy processes.


title: Not-so-normal mode decomposition

abstract:
  We provide a generalization of the normal mode decomposition for
non-symmetric or locality constrained situations. This allows for instance to
locally decouple a bipartitioned collection of arbitrarily correlated
oscillators up to elementary pairs into which all correlations are condensed.
Similarly, it enables us to decouple the interaction parts of multi-mode
channels into single-mode and pair-interactions where the latter are shown to
be a clear signature of squeezing between system and environment. In
mathematical terms the result is a canonical matrix form with respect to real
symplectic equivalence transformations.


title: Do O-stars form in isolation?

abstract:
  Around 4% of O-stars are observed in apparent isolation, with no associated
cluster, and no indication of having been ejected from a nearby cluster. We
define an isolated O-star as a star > 17.5 M_\odot in a cluster with total mass
<100 M_\odot which contains no other massive (>10 M_\odot) stars. We show that
the fraction of apparently isolated O-stars is reproduced when stars are
sampled (randomly) from a standard initial mass function and a standard cluster
mass function of the form N(M) \propto M^-2.
  This result is difficult to reconcile with the idea that there is a
fundamental relationship between the mass of a cluster and the mass of the most
massive star in that cluster. We suggest that such a relationship is a typical
result of star formation in clusters, and that `isolated O-stars' are low-mass
clusters in which massive stars have been able to form.


title:
Infinite Horizon and Ergodic Optimal Quadratic Control for an Affine
  Equation with Stochastic Coefficients

abstract:
  We study quadratic optimal stochastic control problems with control dependent
noise state equation perturbed by an affine term and with stochastic
coefficients. Both infinite horizon case and ergodic case are treated. To this
purpose we introduce a Backward Stochastic Riccati Equation and a dual backward
stochastic equation, both considered in the whole time line. Besides some
stabilizability conditions we prove existence of a solution for the two
previous equations defined as limit of suitable finite horizon approximating
problems. This allows to perform the synthesis of the optimal control.


title: A Magnus- and Fer-type formula in dendriform algebras

abstract:
  We provide a refined approach to the classical Magnus and Fer expansion,
unveiling a new structure by using the language of dendriform and pre-Lie
algebras. The recursive formula for the logarithm of the solutions of the
equations X=1+ta<X and Y=1-tY> a in A[[t]] is provided, where (A,<,>) is a
dendriform algebra. Then, we present the solutions to these equations as an
infinite product expansion of exponentials. Both formulae involve the pre-Lie
product naturally associated with the dendriform structure. Several
applications are presented.


title:
Fluctuation-induced first order transition due to Griffiths anomalies of
  the Cluster glass phase

abstract:
  In itinerant magnetic systems with disorder, the quantum Griffiths phase at
T=0 is unstable to formation of a cluster glass (CG) of frozen droplet degrees
of freedom. In the absence of the fluctuations associated with these degrees of
freedom, the transition from the paramagnetic Fermi liquid (PMFL) to the
ordered phase proceeds via a conventional second-order quantum phase
transition. However, when the Griffiths anomalies due to the broad distribution
of local energy scales are included, the transition is driven first-order via a
novel mechanism for a fluctuation induced first-order transition. At higher
temperatures, thermal effects restore the transition to second-order.
Implications of the enhanced non-Ohmic dissipation in the CG phase are briefly
discussed.


title: Maps of random walks on complex networks reveal community structure

abstract:
  To comprehend the multipartite organization of large-scale biological and
social systems, we introduce a new information theoretic approach that reveals
community structure in weighted and directed networks. The method decomposes a
network into modules by optimally compressing a description of information
flows on the network. The result is a map that both simplifies and highlights
the regularities in the structure and their relationships. We illustrate the
method by making a map of scientific communication as captured in the citation
patterns of more than 6000 journals. We discover a multicentric organization
with fields that vary dramatically in size and degree of integration into the
network of science. Along the backbone of the network -- including physics,
chemistry, molecular biology, and medicine -- information flows
bidirectionally, but the map reveals a directional pattern of citation from the
applied fields to the basic sciences.


title: Unfolding Orthogonal Terrains

abstract:
  It is shown that every orthogonal terrain, i.e., an orthogonal (right-angled)
polyhedron based on a rectangle that meets every vertical line in a segment,
has a grid unfolding: its surface may be unfolded to a single non-overlapping
piece by cutting along grid edges defined by coordinate planes through every
vertex.


title:
Circumnuclear Gas in Seyfert 1 Galaxies: Morphology, Kinematics, and
  Direct Measurement of Black Hole Masses

abstract:
  (Abridged) The two-dimensional distribution and kinematics of the molecular,
ionized, and highly ionized gas in the nuclear regions of Seyfert 1 galaxies
have been measured using high spatial resolution (~0''.09) near-infrared
spectroscopy from NIRSPEC with adaptive optics on the Keck telescope. Molecular
hydrogen, H2, is detected in all nine Seyfert 1 galaxies and, in the majority
of galaxies, has a spatially resolved flux distribution. In contrast, the
narrow component of the BrG emission has a distribution consistent with that of
the K-band continuum. In general, the kinematics of H2 are consistent with thin
disk rotation, with a velocity gradient of over 100 km/s measured across the
central 0''.5 in three galaxies, and across the central 1''.5 in two galaxies.
The kinematics of BrG are in agreement with the H2 rotation, except in all four
cases the central 0''.5 is either blue- or redshifted by more than 75 km/s. The
highly ionized gas, measured with the [Ca VIII] and [Si VII] coronal lines, is
spatially and kinematically consistent with BrG in the central 0''.5. Dynamical
models have been fitted to the two-dimensional H2 kinematics, taking into
account the stellar mass distribution, the emission line flux distribution, and
the point spread function. For NGC 3227 the modeling indicates a black hole
mass of Mbh = 2.0{+1.0/-0.4} x 10^7 Msun, and for NGC 4151 Mbh =
3.0{+0.75/-2.2} x 10^7 Msun. In NGC 7469 the best fit model gives Mbh < 5.0 x
10^7 Msun. In all three galaxies, modeling suggests a near face-on disk
inclination angle, which is consistent with the unification theory of active
galaxies. The direct black hole mass estimates verify that masses determined
from the technique of reverberation mapping are accurate to within a factor of
three with no additional systematic errors.


title:
Spectral Analysis of a Family of Second-Order Elliptic Operators with
  Nonlocal Boundary Condition Indexed by a Probabilty Measure

abstract:
  Let $D\subset R^d$ be a bounded domain and let \[ L=\frac12\nabla\cdot
a\nabla +b\cdot\nabla \] %\[
%L=\frac12\sum_{i,j=1}^da_{i,j}\frac{\partial^2}{\partial x_i\partial
x_j}+\sum_{i=1}^db_i\frac{\partial}{\partial x_i}, %\] be a second order
elliptic operator on $D$. Let $\nu$ be a probability measure on $D$.
  Denote by ${\mathcal L}$ the differential operator whose domain is specified
by the following non-local boundary condition: $$ {\mathcal D_{{\mathcal
L}}}=\{f\in C^2(\ol{D}): \int_D f d\nu = f|_{\partial D}\}, $$ and which
coincides with $L$ on its domain. It is known that $\mathcal L$ possesses an
infinite sequence of eigenvalues, and that with the exception of the zero
eigenvalue, all eigenvalues have negative real part. Define the spectral gap of
$\mathcal {L}$, indexed by $\nu$, by
  \gamma_1(\nu)\equiv\sup\{\re \lambda:0\neq \lambda is an eigenvalue for
{\mathcal L}\}.
  In this paper we investigate the eigenvalues of $\mathcal L$ in general and
the spectral gap $\gamma_1(\nu)$ in particular. The operator $\mathcal L$ is
the generator of a diffusion process with random jumps from the boundary, and
$\gamma_1(\nu)$ measures the exponential rate of convergence of this process to
its invariant measure.


title:
Ferromagnetic behaviour in the strongly interacting two-component Bose
  gas

abstract:
  We investigate the low temperature behaviour of the integrable 1D
two-component spinor Bose gas using the thermodynamic Bethe ansatz. We find
that for strong coupling the characteristics of the thermodynamics at low
temperatures are quantitatively affected by the spin ferromagnetic states,
which are described by an effective ferromagnetic Heisenberg chain. The free
energy, specific heat, susceptibility and local pair correlation function are
calculated for various physical regimes in terms of temperature and interaction
strength. These thermodynamic properties reveal spin effects which are
significantly different than those of the spinless Bose gas. The zero-field
susceptibility for finite strong repulsion exceeds that of a free spin
paramagnet. The critical exponents of the specific heat $c_v \sim T^{1/2}$ and
the susceptibility $\chi \sim T^{-2}$ are indicative of the ferromagnetic
signature of the two-component spinor Bose gas. Our analytic results are
consistent with general arguments by Eisenberg and Lieb for polarized spinor
bosons.


title: The bitwisted Cartesian model for the free loop fibration

abstract:
  Using the notion of truncating twisting function from a simplicial set to a
cubical set a special, bitwisted, Cartesian product of these sets is defined.
For the universal truncating twisting function, the (co)chain complex of the
corresponding bitwisted Cartesian product agrees with the standard Cartier
(Hochschild) chain complex of the simplicial (co)chains. The modelling
polytopes $F_n$ are constructed. An explicit diagonal on $F_n$ is defined and a
multiplicative model for the free loop fibration $\Omega Y\to \Lambda Y\to Y$
is obtained. As an application we establish an algebra isomorphism $H^*(\Lambda
Y;\mathbb{Z}) \approx S(U)\otimes \Lambda(s^{_{-1}}U)$ for the polynomial
cohomology algebra $H^*(Y;\mathbb{Z})=S(U).$


title: Gibbs' paradox and black-hole entropy

abstract:
  In statistical mechanics Gibbs' paradox is avoided if the particles of a gas
are assumed to be indistinguishable. The resulting entropy then agrees with the
empirically tested thermodynamic entropy up to a term proportional to the
logarithm of the particle number. We discuss here how analogous situations
arise in the statistical foundation of black-hole entropy. Depending on the
underlying approach to quantum gravity, the fundamental objects to be counted
have to be assumed indistinguishable or not in order to arrive at the
Bekenstein--Hawking entropy. We also show that the logarithmic corrections to
this entropy, including their signs, can be understood along the lines of
standard statistical mechanics. We illustrate the general concepts within the
area quantization model of Bekenstein and Mukhanov.


title: Geometrical and Physical Properties of SXR Loop-Top Flare Kernels

abstract:
  We investigate how the geometrical and physical properties of soft X-ray
flare kernels change with their altitude above the photosphere. We analyze limb
flares well observed by {\em Yohkoh}/SXT showing clear geometry with well
separated loop-top kernels. Our analysis concerns relations between kernel
size, plasma pressure, energy release and the kernel altitude. We define
scaling laws describing how the sizes and its physical properties of kernels
vary with the altitude above the photosphere. We interpret the observed
relations in terms of the general magnetic structure of active regions.


title:
Dynamics of Jupiter Trojans during the 2:1 mean motion resonance
  crossing of Jupiter and Saturn

abstract:
  We study the dynamics of Jupiter Trojans in the early phase of the Solar
system while the outer planets migrated due to their interaction with the
planetesimal disk.


title:
Implications of Compressed Supersymmetry for Collider and Dark Matter
  Searches

abstract:
  Martin has proposed a scenario dubbed ``compressed supersymmetry'' (SUSY)
where the MSSM is the effective field theory between energy scales M_{\rm weak}
and M_{\rm GUT}, but with the GUT scale SU(3) gaugino mass M_3<< M_1 or M_2. As
a result, squark and gluino masses are suppressed relative to slepton, chargino
and neutralino masses, leading to a compressed sparticle mass spectrum, and
where the dark matter relic density in the early universe may be dominantly
governed by neutralino annihilation into ttbar pairs via exchange of a light
top squark. We explore the dark matter and collider signals expected from
compressed SUSY for two distinct model lines with differing assumptions about
GUT scale gaugino mass parameters. For dark matter signals, the compressed
squark spectrum leads to an enhancement in direct detection rates compared to
models with unified gaugino masses. Meanwhile, neutralino halo annihilation
rates to gamma rays and anti-matter are also enhanced relative to related
scenarios with unified gaugino masses but, depending on the halo dark matter
distribution, may yet be below the sensitivity of indirect searches underway.
In the case of collider signals, we compare the rates for the potentially
dominant decay modes of the stop_1 which may be expected to be produced in
cascade decay chains at the LHC: \tst_1\to c\tz_1 and \tst_1\to bW\tz_1. We
examine the extent to which multilepton signal rates are reduced when the
two-body decay mode dominates. For the model lines that we examine here, the
multi-lepton signals, though reduced, still remain observable at the LHC.


title:
Markov evolutions and hierarchical equations in the continuum I.
  One-component systems

abstract:
  General birth-and-death as well as hopping stochastic dynamics of infinite
particle systems in the continuum are considered. We derive corresponding
evolution equations for correlation functions and generating functionals.
General considerations are illustrated in a number of concrete examples of
Markov evolutions appearing in applications.


title: A generalized no-broadcasting theorem

abstract:
  We prove a generalized version of the no-broadcasting theorem, applicable to
essentially \emph{any} nonclassical finite-dimensional probabilistic model
satisfying a no-signaling criterion, including ones with ``super-quantum''
correlations. A strengthened version of the quantum no-broadcasting theorem
follows, and its proof is significantly simpler than existing proofs of the
no-broadcasting theorem.


title: Diffractive Optics for Gravitational Wave Detectors

abstract:
  All-reflective interferometry based on nano-structured diffraction gratings
offers new possibilities for gravitational wave detection. We investigate an
all-reflective Fabry-Perot interferometer concept in 2nd order Littrow mount.
The input-output relations for such a resonator are derived treating the
grating coupler by means of a scattering matrix formalism. A low loss
dielectric reflection grating has been designed and manufactured to test the
properties of such a grating cavity.


title: On prospects for dark matter indirect detection in the Constrained MSSM

abstract:
  In the framework of the Constrained MSSM we derive the most probable ranges
of the diffuse gamma radiation flux from the direction of the Galactic center
and of the positron flux from the Galactic halo due to neutralino dark matter
annihilation. We find that, for a given halo model, and assuming flat priors,
the 68% probability range of the integrated gamma-ray flux spans about one
order of magnitude, while the 95% probability range can be much larger and
extend over four orders of magnitude (even exceeding five for a tiny region at
small neutralino mass). The detectability of the signal by GLAST depending
primarily on the cuspiness of the halo profile. The positron flux, on the other
hand, appears to be too small to be detectable by PAMELA, unless the boost
factor is at least of order ten and/or the halo profile is extremely cuspy. We
also briefly discuss the sensitivity of our results to the choice of priors.


title: An analysis of the fluctuations of the geomagnetic dipole

abstract:
  The time evolution of the strength of the Earth's virtual axial dipole moment
(VADM) is analyzed by relating it to the Fokker-Planck equation, which
describes a random walk with VADM-dependent drift and diffusion coefficients.
We demonstrate first that our method is able to retrieve the correct shape of
the drift and diffusion coefficients from a time series generated by a test
model. Analysis of the Sint-2000 data shows that the geomagnetic dipole mode
has a linear growth time of 13 to 33 kyr, and that the nonlinear quenching of
the growth rate follows a quadratic function of the type [1-(x/x0)^2]. On
theoretical grounds, the diffusive motion of the VADM is expected to be driven
by multiplicative noise, and the corresponding diffusion coefficient to scale
quadratically with dipole strength. However, analysis of the Sint-2000 VADM
data reveals a diffusion which depends only very weakly on the dipole strength.
This may indicate that the magnetic field quenches the amplitude of the
turbulent velocity in the Earth's outer core.


title: Kinematical Studies of the Low Mass X-Ray Binary GR Mus (XB1254-690)

abstract:
  We present simultaneous high-resolution optical spectroscopy and X-ray data
of the X-ray binary system GR Mus (XB1254-690), obtained over a full range of
orbital phases. The X-ray observations are used to re-establish the orbital
ephemeris for this source. The optical data includes the first spectroscopic
detection of the donor star in this system, through the use of the Doppler
Tomography technique on the Bowen fluorescence blend (~4630-4650 A). In
combination with an estimate for the orbital parameters of the compact object
using the wings of the He II 4686 emission line, dynamical mass constraints of
1.20 < M_X/M_{sun} < 2.64 for the neutron star and 0.45 < M_2/M_{sun} < 0.85
for the companion are derived.


title: Input-output relations for a 3-port grating coupled Fabry-Perot cavity

abstract:
  We analyze an optical 3-port reflection grating by means of a scattering
matrix formalism. Amplitude and phase relations between the 3 ports, i.e. the 3
orders of diffraction are derived. Such a grating can be used as an
all-reflective, low-loss coupler to Fabry-Perot cavities. We derive the input
output relations of a 3-port grating coupled cavity and find distinct
properties not present in 2-port coupled cavities. The cavity relations further
reveal that the 3-port coupler can be designed such that the additional cavity
port interferes destructively. In this case the all-reflective, low-loss,
single-ended Fabry-Perot cavity becomes equivalent to a standard transmissive,
2-port coupled cavity.


title:
The importance of thermal disorder and electronic occupation for the
  T-dependence of the optical conductivity in FeSi and MnSi

abstract:
  The spectral weight (SW) for optical transitions in FeSi and MnSi are
calculated as function of temperature by means of LMTO-LDA band calculations.
The main effects, caused by structural disorder and electronic Fermi-Dirac
distribution, act oppositely on the T-dependence of the SW, while the variation
of the magnetic moment in MnSi has only a minor effect. The calculations agree
with the experimental findings of an increasing SW in FeSi and a decreasing SW
in MnSi as function of T. The results can be understood from the change of the
bandstructure with disorder.


title:
Dependence of Temporal Properties on Energy in Long-Lag, Wide-Pulse
  Gamma-Ray Bursts

abstract:
  We employed a sample compiled by Norris et al. (2005, ApJ, 625, 324) to study
the dependence of the pulse temporal properties on energy in long-lag,
wide-pulse gamma-ray bursts. Our analysis shows that the pulse peak time, rise
time scale and decay time scale are power law functions of energy, which is a
preliminary report on the relationships between the three quantities and
energy. The power law indexes associated with the pulse width, rise time scale
and decay time scale are correlated and the correlation between the indexes
associated with the pulse width and the decay time scale is more obvious. In
addition, we have found that the pulse peak lag is strongly correlated with the
CCF lag, but the centroid lag is less correlated with the peak lag and CCF lag.
Based on these results and some previous investigations, we tend to believe
that all energy-dependent pulse temporal properties may come from the joint
contribution of both the hydrodynamic processes of the outflows and the
curvature effect, where the energy-dependent spectral lag may be mainly
dominated by the dynamic process and the energy-dependent pulse width may be
mainly determined by the curvature effect.


title: Dark Matter in a Constrained NMSSM

abstract:
  We explore the parameter space of a Constrained Next-to-Minimal
Supersymmetric Standard Model with GUT scale boundary conditions (CNMSSM) and
find regions where the relic density of the lightest neutralino is compatible
with the WMAP measurement. We emphasize differences with the MSSM: cases where
annihilation of the LSP occurs via a Higgs resonance at low values of tan\beta
and cases where the LSP has a large singlino component. The particle spectrum
as well as theoretical and collider constraints are calculated with NMSSMTools.
All neutralino annihilation and coannihilation processes are then computed with
micrOMEGAs, taking into account higher order corrections to the Higgs sector.


title: Penrose Quantum Antiferromagnet

abstract:
  The Penrose tiling is a perfectly ordered two dimensional structure with
fivefold symmetry and scale invariance under site decimation. Quantum spin
models on such a system can be expected to differ significantly from more
conventional structures as a result of its special symmetries. In one
dimension, for example, aperiodicity can result in distinctive quantum
entanglement properties. In this work, we study ground state properties of the
spin-1/2 Heisenberg antiferromagnet on the Penrose tiling, a model that could
also be pertinent for certain three dimensional antiferromagnetic
quasicrystals. We show, using spin wave theory and quantum Monte Carlo
simulation, that the local staggered magnetizations strongly depend on the
local coordination number z and are minimized on some sites of five-fold
symmetry. We present a simple explanation for this behavior in terms of
Heisenberg stars. Finally we show how best to represent this complex
inhomogeneous ground state, using the "perpendicular space" representation of
the tiling.


title: Demonstration of 3-port grating phase relations

abstract:
  We experimentally demonstrate the phase relations of 3-port gratings by
investigating 3-port coupled Fabry-Perot cavities. Two different gratings which
have the same 1st order diffraction efficiency but differ substantially in
their 2nd order diffraction efficiency have been designed and manufactured.
Using the gratings as couplers to Fabry-Perot cavities we could validate the
results of an earlier theoretical description of the phases at a three port
grating.


title:
On the environmental decoherence and spin interference in mesoscopic
  loop structures

abstract:
  Mechanisms of 'environmental decoherence' such as surface scattering,
Elliot-Yafet process and precession mechanisms, as well as their influence on
the spin phase relaxation are considered and compared. It is shown that the
'spin ballistic' regime is possible, when the phase relaxation length for the
spin part of the wave function (WF)is much greater than the phase relaxation
length for the 'orbital part'. In the presence of an additional magnetic field,
the spin part of the electron's WF acquires a phase shift due to additional
spin precession about that field. If the structure length is chosen to be
greater than the phase relaxation length for the 'orbital part' and less than
the phase relaxation length for the spin part of WF, it is possible to 'wash
out' the quantum interference related to the phase coherence of the 'orbital
part' of the WF, retaining at the same time that related to the phase coherence
of the spin part and, hence, to reveal corresponding conductance oscillations.


title:
Pseudoscalar Goldstone bosons in the color-flavor locked phase at
  moderate densities

abstract:
  The properties of the pseudoscalar Goldstone bosons in the color-flavor
locked phase at moderate densities are studied within a model of the
Nambu--Jona-Lasinio type. The Goldstone bosons are constructed explicitly by
solving the Bethe-Salpeter equation for quark-quark scattering in random phase
approximation. Main focus of our investigations are (i) the weak decay constant
in the chiral limit, (ii) the masses of the flavored (pseudo-) Goldstone bosons
for non-zero but equal quark masses, (iii) their masses and effective chemical
potentials for non-equal quark masses, and (iv) the onset of kaon condensation.
We compare our results with the predictions of the low-energy effective field
theory. The deviations from results obtained in the weak-coupling limit are
discussed in detail.


title: Electroweak Symmetry Breaking induced by Dark Matter

abstract:
  The mechanism behind Electroweak Symmetry Breaking (EWSB) and the nature of
dark matter (DM) are currently among the most important issues in high energy
physics. Since a natural dark matter candidate is a weakly interacting massive
particle or WIMP, with mass around the electroweak scale, it is clearly of
interest to investigate the possibility that DM and EWSB are closely related.
In the context of a very simple extension of the Standard Model, the Inert
Doublet Model, we show that dark matter could play a crucial role in the
breaking of the electroweak symmetry. In this model, dark matter is the
lightest component of an inert scalar doublet. The coupling of the latter with
the Standard Model Higgs doublet breaks the electroweak symmetry at one-loop,
"a la Coleman-Weinberg". The abundance of dark matter, the breaking of the
electroweak symmetry and the constraints from electroweak precision
measurements can all be accommodated by imposing an (exact or approximate)
custodial symmetry.


title: Sporadic Long-term Variability in Radio Activity from a Brown Dwarf

abstract:
  Radio activity has been observed in a large variety of stellar objects,
including in the last few years, ultra-cool dwarfs. To explore the extent of
long-term radio activity in ultra-cool dwarfs, we use data taken over an
extended period of 9 hr from the Very Large Array of the source 2MASS
J05233822-1403022 in September 2006, plus data taken in 2004. The observation
taken in September 2006 failed to detect any radio activity at 8.46 GHz. A
closer inspection of earlier data reveals that the source varied from a null
detection on 3 May 2004, to $\approx$95 $\mu$Jy on 17 May 2004, to 230 $\mu$Jy
on 18 June 2004. The lack of detection in September 2006 suggests at least a
factor of ten flux variability at 8.46 GHz. Three short photometric runs did
not reveal any optical variability. In addition to the observed pulsing nature
of the radio flux from another ultra-cool source, the present observations
suggests that ultra-cool dwarfs may not just be pulsing but can also display
long-term sporadic variability in their levels of quiescent radio emission. The
lack of optical photometric variability suggests an absence of large-scale
spots at the time of the latest VLA observations, although small very high
latitude spots combined with a low inclination could cause very low amplitude
rotational modulation which may not be measurable. We discuss this large
variability in the radio emission within the context of both gyrosynchrotron
emission and the electron-cyclotron maser, favoring the latter mechanism.


title:
Possible Connection between Probability, Spacetime Geometry and Quantum
  Mechanics

abstract:
  Following our discussion [Physica A, 375 (2007) 123] to associate an
analogous probabilistic description with spacetime geometry in the
Schwarzschild metric from the macro- to the micro-domain, we argue that there
is a possible connection among normalized probabilities, spacetime geometry (in
the form of Schwarzschild radii) and quantum mechanics (in the form of complex
wave functions). We show how this association along different (n)-nested
surfaces --representing curve space due to an inhomogeneous density of matter--
preserves the postulates of quantum mechanics at different geometrical scales.


title:
Model-independent constraints on Delta F=2 operators and the scale of
  New Physics

abstract:
  We update the constraints on new-physics contributions to Delta F=2 processes
from the generalized unitarity triangle analysis, including the most recent
experimental developments. Based on these constraints, we derive upper bounds
on the coefficients of the most general Delta F=2 effective Hamiltonian. These
upper bounds can be translated into lower bounds on the scale of new physics
that contributes to these low-energy effective interactions. We point out that,
due to the enhancement in the renormalization group evolution and in the matrix
elements, the coefficients of non-standard operators are much more constrained
than the coefficient of the operator present in the Standard Model. Therefore,
the scale of new physics in models that generate new Delta F=2 operators, such
as next-to-minimal flavour violation, has to be much higher than the scale of
minimal flavour violation, and it most probably lies beyond the reach of direct
searches at the LHC.


title: Microelectromechanical components in electrical metrology

abstract:
  Microelectromechanical systems (MEMS) can offer a competitive alternative for
conventional technology in electrical precision measurements. This article
summarises recent work in development of MEMS solutions for electrical
metrology. MEMS-based voltage references, RMS-to-DC converters, high frequency
power sensors, and reference oscillators are discussed. The main principle of
operation of the components is the balance between electrical forces and
mechanical spring forces in micromachined silicon structures. In RMS sensors
and RMS-to-DC converters, the quadratic voltage dependence of the force between
plates of a moving-plate capacitor is utilised, and the operation of the MEMS
voltage reference is based on the pull-in phenomenon of a moving-plate
capacitor. Advantages of MEMS devices compared to more conventional solutions
include small size, low power consumption, low price in mass production, and
stability. The drift caused by electrostatic charging effects has turned out to
be a major problem. This problem has not yet been solved in DC applications,
but it can be circumvented by using AC actuation instead of DC and by
compensating the internal DC voltages of the component. In this way, an AC
voltage reference with relative drift rate below 2 ppm during a three-week test
period has been constructed. Even better stability has been demonstrated with a
MEMS-based reference oscillator: no changes in resonance frequency were
observed at relative uncertainty level of about 0.01 ppm in a measurement which
was continued for more than a month. MEMS components have also been developed
for measuring RF and microwave power up to frequencies of about 40 GHz. Unlike
conventional high frequency power sensors, which measure the absorbed power,
the MEMS device measures the power that is transmitted through the sensor.


title:
Core-mantle boundary deformations and J2 variations resulting from the
  2004 Sumatra earthquake

abstract:
  The deformation at the core-mantle boundary produced by the 2004 Sumatra
earthquake is investigated by means of a semi-analytic theoretical model of
global coseismic and postseismic deformation, predicting a millimetric
coseismic perturbation over a large portion of the core-mantle boundary.
Spectral features of such deformations are analysed and discussed. The
time-dependent postseismic evolution of the elliptical part of the gravity
field (J2) is also computed for different asthenosphere viscosity models. Our
results show that, for asthenospheric viscosities smaller than 10^18 Pa s, the
postseismic J2 variation in the next years is expected to leave a detectable
signal in geodetic observations.


title:
Hopping and clustering of oxygen vacancies in SrTiO3 by anelastic
  relaxation

abstract:
  The complex elastic compliance s11(w,T) of SrTiO3-d has been measured as a
function of the O deficiency d < 0.01. The two main relaxation peaks in the
absorption are identified with hopping of isolated O vacancies over a barrier
of 0.60 eV and reorientation of pairs of vacancies involving a barrier of 1 eV.
The pair binding energy is ~0.2 eV and indications for additional clustering,
possibly into chains, is found already at d ~0.004. The anistropic component of
the elastic dipole of an O vacancy is Deltalambda = 0.026.


title:
Derivation of a Non-Local Interfacial Hamiltonian for Short-Ranged
  Wetting II: General Diagrammatic Structure

abstract:
  In our first paper, we showed how a non-local effective Hamiltionian for
short-ranged wetting may be derived from an underlying Landau-Ginzburg-Wilson
model. Here, we combine the Green's function method with standard perturbation
theory to determine the general diagrammatic form of the binding potential
functional beyond the double-parabola approximation for the
Landau-Ginzburg-Wilson bulk potential. The main influence of cubic and quartic
interactions is simply to alter the coefficients of the double parabola-like
zig-zag diagrams and also to introduce curvature and tube-interaction
corrections (also represented diagrammatically), which are of minor importance.
Non-locality generates effective long-ranged many-body interfacial interactions
due to the reflection of tube-like fluctuations from the wall. Alternative wall
boundary conditions (with a surface field and enhancement) and the diagrammatic
description of tricritical wetting are also discussed.


title: Where are Bottlenecks in NK Fitness Landscapes?

abstract:
  Usually the offspring-parent fitness correlation is used to visualize and
analyze some caracteristics of fitness landscapes such as evolvability. In this
paper, we introduce a more general representation of this correlation, the
Fitness Cloud (FC). We use the bottleneck metaphor to emphasise fitness levels
in landscape that cause local search process to slow down. For a local search
heuristic such as hill-climbing or simulated annealing, FC allows to visualize
bottleneck and neutrality of landscapes. To confirm the relevance of the FC
representation we show where the bottlenecks are in the well-know NK fitness
landscape and also how to use neutrality information from the FC to combine
some neutral operator with local search heuristic.


title: Spectral Modeling of Turbulent Flows and the Role of Helicity

abstract:
  We present a new version of a dynamical spectral model for Large Eddy
Simulation based on the Eddy Damped Quasi Normal Markovian approximation
\cite{sao,chollet_lesieur}. Three distinct modifications are implemented and
tested. On the one hand, whereas in current approaches, a Kolmogorov-like
energy spectrum is usually assumed in order to evaluate the nonlocal transfer,
in our method the energy spectrum of the subgrid scales adapts itself
dynamically to the large-scale resolved spectrum; this first modification
allows in particular for a better treatment of transient phases and
instabilities, as shown on one specific example. Moreover, the model takes into
account the phase relationships of the small-scales, embodied for example in
strong localized structures such as vortex filaments. To that effect, phase
information is implemented in the treatment of the so-called eddy noise in the
closure model. Finally, we also consider the role that helical small scales may
play in the evaluation of the transfer of energy and helicity, the two
invariants of the primitive equations in the inviscid case; this leads as well
to intrinsic variations in the development of helicity spectra. Therefore, our
model allows for simulations of flows for a variety of circumstances and a
priori at any given Reynolds number. Comparisons with Direct Numerical
Simulations of the three-dimensional Navier-Stokes equation are performed on
fluids driven by an ABC (Beltrami) flow which is a prototype of fully helical
flows. Good agreements are obtained for physical and spectral behavior of the
large scales.


title: Scuba Search : when selection meets innovation

abstract:
  We proposed a new search heuristic using the scuba diving metaphor. This
approach is based on the concept of evolvability and tends to exploit
neutrality in fitness landscape. Despite the fact that natural evolution does
not directly select for evolvability, the basic idea behind the scuba search
heuristic is to explicitly push the evolvability to increase. The search
process switches between two phases: Conquest-of-the-Waters and
Invasion-of-the-Land. A comparative study of the new algorithm and standard
local search heuristics on the NKq-landscapes has shown advantage and limit of
the scuba search. To enlighten qualitative differences between neutral search
processes, the space is changed into a connected graph to visualize the
pathways that the search is likely to follow.


title: Another view of the Gaussian algorithm

abstract:
  We introduce here a rewrite system in the group of unimodular matrices,
\emph{i.e.}, matrices with integer entries and with determinant equal to $\pm
1$. We use this rewrite system to precisely characterize the mechanism of the
Gaussian algorithm, that finds shortest vectors in a two--dimensional lattice
given by any basis. Putting together the algorithmic of lattice reduction and
the rewrite system theory, we propose a new worst--case analysis of the
Gaussian algorithm. There is already an optimal worst--case bound for some
variant of the Gaussian algorithm due to Vall\'ee \cite {ValGaussRevisit}. She
used essentially geometric considerations. Our analysis generalizes her result
to the case of the usual Gaussian algorithm. An interesting point in our work
is its possible (but not easy) generalization to the same problem in higher
dimensions, in order to exhibit a tight upper-bound for the number of
iterations of LLL--like reduction algorithms in the worst case. Moreover, our
method seems to work for analyzing other families of algorithms. As an
illustration, the analysis of sorting algorithms are briefly developed in the
last section of the paper.


title: Equation of motion for dislocations with inertial effects

abstract:
  An approximate equation of motion is proposed for screw and edge
dislocations, which accounts for retardation and for relativistic effects in
the subsonic range. Good quantitative agreement is found, in accelerated or in
decelerated regimes, with numerical results of a more fundamental nature.


title: Two loop superstring amplitudes and S_6 representations

abstract:
  In this paper we describe how representation theory of groups can be used to
shorten the derivation of two loop partition functions in string theory, giving
an intrinsic description of modular forms appearing in the results of D'Hoker
and Phong [1]. Our method has the advantage of using only algebraic properties
of modular functions and it can be extended to any genus g.


title:
Two types of generalized integrable decompositions and new solitary-wave
  solutions for the modified Kadomtsev-Petviashvili equation with symbolic
  computation

abstract:
  The modified Kadomtsev-Petviashvili (mKP) equation is shown in this paper to
be decomposable into the first two soliton equations of the 2N-coupled
Chen-Lee-Liu and Kaup-Newell hierarchies by respectively nonlinearizing two
sets of symmetry Lax pairs. In these two cases, the decomposed
(1+1)-dimensional nonlinear systems both have a couple of different Lax
representations, which means that there are two linear systems associated with
the mKP equation under the same constraint between the potential and
eigenfunctions. For each Lax representation of the decomposed (1+1)-dimensional
nonlinear systems, the corresponding Darboux transformation is further
constructed such that a series of explicit solutions of the mKP equation can be
recursively generated with the assistance of symbolic computation. In
illustration, four new families of solitary-wave solutions are presented and
the relevant stability is analyzed.


title: Dial a Ride from k-forest

abstract:
  The k-forest problem is a common generalization of both the k-MST and the
dense-$k$-subgraph problems. Formally, given a metric space on $n$ vertices
$V$, with $m$ demand pairs $\subseteq V \times V$ and a ``target'' $k\le m$,
the goal is to find a minimum cost subgraph that connects at least $k$ demand
pairs. In this paper, we give an $O(\min\{\sqrt{n},\sqrt{k}\})$-approximation
algorithm for $k$-forest, improving on the previous best ratio of
$O(n^{2/3}\log n)$ by Segev & Segev.
  We then apply our algorithm for k-forest to obtain approximation algorithms
for several Dial-a-Ride problems. The basic Dial-a-Ride problem is the
following: given an $n$ point metric space with $m$ objects each with its own
source and destination, and a vehicle capable of carrying at most $k$ objects
at any time, find the minimum length tour that uses this vehicle to move each
object from its source to destination. We prove that an $\alpha$-approximation
algorithm for the $k$-forest problem implies an
$O(\alpha\cdot\log^2n)$-approximation algorithm for Dial-a-Ride. Using our
results for $k$-forest, we get an $O(\min\{\sqrt{n},\sqrt{k}\}\cdot\log^2 n)$-
approximation algorithm for Dial-a-Ride. The only previous result known for
Dial-a-Ride was an $O(\sqrt{k}\log n)$-approximation by Charikar &
Raghavachari; our results give a different proof of a similar approximation
guarantee--in fact, when the vehicle capacity $k$ is large, we give a slight
improvement on their results.


title: Sphere Lower Bound for Rotated Lattice Constellations in Fading Channels

abstract:
  We study the error probability performance of rotated lattice constellations
in frequency-flat Nakagami-$m$ block-fading channels. In particular, we use the
sphere lower bound on the underlying infinite lattice as a performance
benchmark. We show that the sphere lower bound has full diversity. We observe
that optimally rotated lattices with largest known minimum product distance
perform very close to the lower bound, while the ensemble of random rotations
is shown to lack diversity and perform far from it.


title: Running mass of the b-quark in QCD and SUSY QCD

abstract:
  The running mass of the b-quark defined in DRbar-scheme is one of the
important parameters of SUSY QCD. To find its value it should be related to
some known experimental input. In this paper the b-quark running mass defined
in nonsupersymmetric QCD is chosen for determination of corresponding parameter
in SUSY QCD. The relation between these two quantities is found by considering
five-flavor QCD as an effective theory obtained from its supersymmetric
extension. A numerical analysis of the calculated two-loop relation and its
impact on the MSSM spectrum is discussed. Since for nonsupersymmetric models
MSbar-scheme is more natural than DRbar, we also propose a new procedure that
allows one to calculate relations between MSbar- and DRbar-parameters.
Unphysical epsilon-scalars that give rise to the difference between mentioned
schemes are assumed to be heavy and decoupled in the same way as physical
degrees of freedom. By means of this method it is possible to ``catch two
rabbits'', i.e., decouple heavy particles and turn from DRbar to MSbar, at the
same time. Explicit two-loop example of DRbar -> MSbar transition is given in
the context of QCD. The advantages and disadvantages of the method are briefly
discussed.


title: Star formation and stellar populations across nuclear rings in galaxies

abstract:
  (Abridged) We present a study of the optical spectra of a sample of eight
star-forming nuclear rings and the nuclei of their host galaxies. The spectra
were obtained with the ISIS spectrograph on the William Herschel Telescope and
cover a wide range in wavelength, enabling the measurement of several stellar
absorption features and gas emission lines.
  We compared the strength of the absorption lines to a variety of population
synthesis models for the star-formation history in the nuclear rings, including
also the contribution of the older bulge and disc stellar components. We find
that the stars in our sample of nuclear rings have most likely formed over a
prolonged period of time characterised by episodic bursts of star-formation
activity. Constant star formation is firmly ruled out by the data, whereas a
one-off formation event is an unlikely explanation for a common galactic
component such as nuclear rings.
  We have used emission-line measurements to constrain the physical conditions
of the ionised gas within the rings. Emission in all nuclear rings originates
from HII-regions with electron densities typical for these kinds of objects,
and that the rings are characterised by values for the gas metallicity ranging
from slightly below to just above solar.
  As 20% of nearby spiral galaxies hosts nuclear rings that are currently
forming massive stars, our finding of an episodic star formation history in
nuclear rings implies that a significant population remains to be identified of
young nuclear rings that are not currently in a massive star formation phase.


title: How to use the Scuba Diving metaphor to solve problem with neutrality ?

abstract:
  We proposed a new search heuristic using the scuba diving metaphor. This
approach is based on the concept of evolvability and tends to exploit
neutrality which exists in many real-world problems. Despite the fact that
natural evolution does not directly select for evolvability, the basic idea
behind the scuba search heuristic is to explicitly push evolvability to
increase. A comparative study of the scuba algorithm and standard local search
heuristics has shown the advantage and the limitation of the scuba search. In
order to tune neutrality, we use the NKq fitness landscapes and a family of
travelling salesman problems (TSP) where cities are randomly placed on a
lattice and where travel distance between cities is computed with the Manhattan
metric. In this last problem the amount of neutrality varies with the city
concentration on the grid ; assuming the concentration below one, this TSP
reasonably remains a NP-hard problem.


title:
Complete Bethe Ansatz solution of the open spin-s XXZ chain with general
  integrable boundary terms

abstract:
  We consider the open spin-s XXZ quantum spin chain with N sites and general
integrable boundary terms for generic values of the bulk anisotropy parameter,
and for values of the boundary parameters which satisfy a certain constraint.
We derive two sets of Bethe Ansatz equations, and find numerical evidence that
together they give the complete set of $(2s+1)^{N}$ eigenvalues of the transfer
matrix. For the case s=1, we explicitly determine the Hamiltonian, and find an
expression for its eigenvalues in terms of Bethe roots.


title:
BRST Anomaly and Superspace Constraints of the Pure Spinor Heterotic
  String in a Curved Background

abstract:
  The pure spinor heterotic string in a generic super Yang-Mills and
supergravity background is considered. We determine the one-loop BRST anomaly
at the cohomological level. We prove that it can be absorbed by consistent
corrections of the classical constraints due to Berkovits and Howe, in
agreement with the Green-Schwarz cancelation mechanism.


title:
Resistive Switching in Cr doped SrTiO3: An X-ray Absorption Spectroscopy
  study

abstract:
  X-ray absorption spectroscopy was used to study the microscopic origin of
conductance and resistive switching in chromium doped strontium titanate
(Cr:SrTiO3). Differences in the x-ray absorption near edge spectroscopy (XANES)
at the Cr K-edge indicate that the valence of Cr changes from 3+ to 4+
underneath the anode of our sample device after the application of an electric
field. Spatially resolved x-ray fluorescence microscopy ($\mu$-XRF) maps show
that the Cr4+ region retracts from the anode-Cr:SrTiO3 interface after a
conducting state has been achieved. This interface region is studied with
extended x-ray absorption fine structure (EXAFS) and the results are compared
with structural parameters obtained from density functional theory (DFT)
calculations. They confirm that oxygen vacancies which are localized at the
octahedron with a Cr at its center are introduced at the interface. It is
proposed that the switching state is not due to a valence change of chromium
but caused by changes of oxygen vacancies at the interface.


title:
Resonance fluorescence from a coherently driven semiconductor quantum
  dot in a cavity

abstract:
  We show that resonance fluorescence, i.e. the resonant emission of a
coherently driven two-level system, can be realized with a semiconductor
quantum dot. The dot is embedded in a planar optical micro-cavity and excited
in a wave-guide mode so as to discriminate its emission from residual laser
scattering. The transition from the weak to the strong excitation regime is
characterized by the emergence of oscillations in the first-order correlation
function of the fluorescence, g(t), as measured by interferometry. The
measurements correspond to a Mollow triplet with a Rabi splitting of up to 13.3
micro eV. Second-order-correlation measurements further confirm non-classical
light emission.


title: Electroweak Hard Photon Bremsstrahlung in Electron-Nucleon Scattering

abstract:
  One way to treat the infrared divergences of the electroweak
Next-to-Leading-Order (NLO) differential cross sections to parity-violating
(PV) electron-proton scattering is by adding soft-photon emission contribution.
Although more physical, the results are left with a logarithmic dependence on
the photon detector acceptance, which can only be eliminated by considering
Hard Photon Bremsstrahlung (HPB) contribution. Here we present a treatment of
HPB for PV electron-proton scattering. HPB differential cross sections for
electron-proton scattering have been computed using the experimental values of
nucleon form factors. The final results are expressed through kinematic
parameters, making it possible to apply the computed PV HPB differential cross
sections for the analysis of data of a range of current and proposed
experiments.


title: Quantum Phase Transitions on Percolating Lattices

abstract:
  When a quantum many-particle system exists on a randomly diluted lattice, its
intrinsic thermal and quantum fluctuations coexist with geometric fluctuations
due to percolation. In this paper, we explore how the interplay of these
fluctuations influences the phase transition at the percolation threshold.
While it is well known that thermal fluctuations generically destroy long-range
order on the critical percolation cluster, the effects of quantum fluctuations
are more subtle. In diluted quantum magnets with and without dissipation, this
leads to novel universality classes for the zero-temperature percolation
quantum phase transition. Observables involving dynamical correlations display
nonclassical scaling behavior that can nonetheless be determined exactly in two
dimensions.


title:
Differential equations in vertex algebras and simple modules for the Lie
  algebra of vector fields on a torus

abstract:
  We study irreducible representations for the Lie algebra of vector fields on
a 2-dimensional torus constructed using the generalized Verma modules. We show
that for a certain choice of parameters these representations remain
irreducible when restricted to a loop subalgebra in the Lie algebra of vector
fields. We prove this result by studying vertex algebras associated with the
Lie algebra of vector fields on a torus and solving non-commutative
differential equations that we derive using the vertex algebra technique.


title: Strong confidence intervals for autoregression

abstract:
  In this short note I apply the methodology of game-theoretic probability to
calculating non-asymptotic confidence intervals for the coefficient of a simple
first order scalar autoregressive model. The most distinctive feature of the
proposed procedure is that with high probability it produces confidence
intervals that always cover the true parameter value when applied sequentially.


title:
Time variation of the fine structure constant in the early universe and
  the Bekenstein model

abstract:
  We calculate bounds on the variation of the fine structure constant at the
time of primordial nucleosynthesis and at the time of neutral hydrogen
formation. We use these bounds and other bounds from the late universe to test
Bekenstein model. We modify the Kawano code, CAMB and CosmoMC in order to
include the possible variation of the fine structure constant. We use
observational primordial abundances of $\De$, $\He$ and $\Li$, recent data from
the Cosmic Microwave Background and the 2dFGRS power spectrum, to obtain bounds
on the variation of $\alpha$. We calculate a piecewise solution to the scalar
field equation of Bekenstein model in two different regimes; i) matter and
radiation, ii) matter and cosmological constant. We match both solutions with
appropriate boundary conditions. We perform a statistical analysis using the
bounds obtained from the early universe and other bounds from the late universe
to constrain the free parameters of the model. Results are consistent with no
variation of $\alpha$ in the early universe. Limits on $\alpha$ are
inconsistent with the scale length of the theory $l$ being larger than Planck
scale. In order to fit all observational and experimental data, the assumption
$l>L_p$ implied in Bekenstein's model has to be relaxed.


title:
Force unfolding kinetics of RNA using optical tweezers. II. Modeling
  experiments

abstract:
  By exerting mechanical force it is possible to unfold/refold RNA molecules
one at a time. In a small range of forces, an RNA molecule can hop between the
folded and the unfolded state with force-dependent kinetic rates. Here, we
introduce a mesoscopic model to analyze the hopping kinetics of RNA hairpins in
an optical tweezers setup. The model includes different elements of the
experimental setup (beads, handles and RNA sequence) and limitations of the
instrument (time lag of the force-feedback mechanism and finite bandwidth of
data acquisition). We investigated the influence of the instrument on the
measured hopping rates. Results from the model are in good agreement with the
experiments reported in the companion article (1). The comparison between
theory and experiments allowed us to infer the values of the intrinsic
molecular rates of the RNA hairpin alone and to search for the optimal
experimental conditions to do the measurements. We conclude that long handles
and soft laser traps represent the best conditions to extract rate estimates
that are closest to the intrinsic molecular rates. The methodology and
rationale presented here can be applied to other experimental setups and other
molecules.

categories: physics.bio-ph cond-mat.soft cond-mat.stat-mech q-bio.BM


title: Spacial Modulation of the Magnetization in Cobalt Nanowires

abstract:
  Cobalt nanowires with a diameter in the range between 50 to 100nm can be
prepared as single-crystal wires with the easy axis (the c-axis) perpendicular
to the wire axis. The competition between the crystal anisotropy and
demagnetization energy frustrates the magnetization direction. A periodic
modulation of the angle between M and the wire axis yields a lower energy.


title: Asymptotic enumeration of 2-covers and line graphs

abstract:
  In this paper we find asymptotic enumerations for the number of line graphs
on $n$-labelled vertices and for different types of related combinatorial
objects called 2-covers.
  We find that the number of 2-covers, $s_n$, and proper 2-covers, $t_n$, on
$[n]$ both have asymptotic growth $$ s_n\sim t_n\sim
B_{2n}2^{-n}\exp(-\frac12\log(2n/\log n))= B_{2n}2^{-n}\sqrt{\frac{\log
n}{2n}}, $$ where $B_{2n}$ is the $2n$th Bell number, while the number of
restricted 2-covers, $u_n$, restricted, proper 2-covers on $[n]$, $v_n$, and
line graphs $l_n$, all have growth $$ u_n\sim v_n\sim l_n\sim
B_{2n}2^{-n}n^{-1/2}\exp(-[\frac12\log(2n/\log n)]^2). $$
  In our proofs we use probabilistic arguments for the unrestricted types of
2-covers and and generating function methods for the restricted types of
2-covers and line graphs.


title:
On the character of states near the Fermi level in (Ga,Mn)As: impurity
  to valence band crossover

abstract:
  We discuss the character of states near the Fermi level in Mn doped GaAs, as
revealed by a survey of dc transport and optical studies over a wide range of
Mn concentrations. A thermally activated valence band contribution to dc
transport, a mid-infrared peak at energy hbar omega approx 200 meV in the ac-
conductivity, and the hot photoluminescence spectra indicate the presence of an
impurity band in low doped (<<1% Mn) insulating GaAs:Mn materials. Consistent
with the implications of this picture, both the impurity band ionization energy
inferred from the dc transport and the position of the mid-infrared peak move
to lower energies and the peak broadens with increasing Mn concentration. In
metallic materials with > 2% doping, no traces of Mn-related activated
contribution can be identified in dc-transport, suggesting that the impurity
band has merged with the valence band. No discrepancies with this perception
are found when analyzing optical measurements in the high-doped GaAs:Mn. A
higher energy (hbar omega approx 250 meV) mid-infrared feature which appears in
the metallic samples is associated with inter-valence band transitions. Its
red-shift with increased doping can be interpreted as a consequence of
increased screening which narrows the localized-state valence-band tails and
weakens higher energy transition amplitudes. Our examination of the dc and ac
transport characteristics of GaAs:Mn is accompanied by comparisons with its
shallow acceptor counterparts, confirming the disordered valence band picture
of high-doped metallic GaAs:Mn material.


title:
Characterization of geodesic flows on T^2 with and without positive
  topological entropy

abstract:
  In the present work we consider the behavior of the geodesic flow on the unit
tangent bundle of the 2-torus $T^2$ for an arbitrary Riemannian metric. A
natural non-negative quantity which measures the complexity of the geodesic
flow is the topological entropy. In particular, positive topological entropy
implies chaotic behavior on an invariant set in the phase space of positive
Hausdorff-dimension (horseshoe). We show that in the case of zero topological
entropy the flow has properties similar to integrable systems. In particular
there exists a non-trivial continuous constant of motion which measures the
direction of geodesics lifted onto the universal covering $\Br^2$. Furthermore,
those geodesics travel in strips bounded by Euclidean lines. Moreover we derive
necessary and sufficient conditions for vanishing topological entropy involving
intersection properties of single geodesics on $T^2$.


title: Information entropy of Gegenbauer polynomials of integer parameter

abstract:
  The position and momentum information entropies of $D$-dimensional quantum
systems with central potentials, such as the isotropic harmonic oscillator and
the hydrogen atom, depend on the entropies of the (hyper)spherical harmonics.
In turn, these entropies are expressed in terms of the entropies of the
Gegenbauer (ultraspherical) polynomials $C_n^{(\lambda)}(x)$, the parameter
$\lambda$ being either an integer or a half-integer number. Up to now, however,
the exact analytical expression of the entropy of Gegenbauer polynomials of
arbitrary degree $n$ has only been obtained for the particular values of the
parameter $\lambda=0,1,2$. Here we present a novel approach to the evaluation
of the information entropy of Gegenbauer polynomials, which makes use of
trigonometric representations for these polynomials and complex integration
techniques. Using this method, we are able to find the analytical expression of
the entropy for arbitrary values of both $n$ and $\lambda\in\mathbb{N}$.


title: Quantum Scattering of Giant Magnons

abstract:
  We perform a first-principles semi-classical computation of the one-loop
corrections to the dispersion relation and S-matrix of Giant Magnons in AdS_5 x
S^5 string theory. The results agree exactly with expectations based on the
strong coupling expansion of the exact Asymptotic Bethe Ansatz equations. In
particular we reproduce the Hernandez-Lopez term in the dressing phase.


title:
Quintessential inflation from 5D warped product spaces on a dynamical
  foliation

abstract:
  Assuming the existence of a 5D purely kinetic scalar field on the class of
warped product spaces we investigate the possibility of mimic both an
inflationary and a quintessential scenarios on 4D hypersurfaces, by
implementing a dynamical foliation on the fifth coordinate instead of a
constant one. We obtain that an induced chaotic inflationary scenario with a
geometrically induced scalar potential and an induced quasi-vacuum equation of
state on 4D dynamical hypersurfaces is possible. While on a constant foliation
the universe can be considered as matter dominated today, in a family of 4D
dynamical hypersurfaces the universe can be passing for a period of accelerated
expansion with a deceleration parameter nearly -1. This effect of the dynamical
foliation results negligible at the inflationary epoch allowing for a chaotic
scenario and becomes considerable at the present epoch allowing a
quintessential scenario.


title:
Theoretical study of even denominator fractions in graphene: Fermi sea
  versus paired states of composite fermions

abstract:
  The physics of the state at even denominator fractional fillings of Landau
levels depends on the Coulomb pseudopotentials, and produces, in different GaAs
Landau levels, a composite fermion Fermi sea, a stripe phase, or, possibly, a
paired composite fermion state. We consider here even denominator fractions in
graphene, which has different pseudopotentials as well as a possible four fold
degeneracy of each Landau level. We test various composite fermion Fermi sea
wave functions (fully polarized, SU(2) singlet, SU(4) singlet) as well as the
paired composite fermion states in the n=0 and $n=1$ Landau levels and predict
that (i) the paired states are not favorable, (ii) CF Fermi seas occur in both
Landau levels, and (iii) an SU(4) singlet composite fermion Fermi sea is
stabilized in the appropriate limit. The results from detailed microscopic
calculations are generally consistent with the predictions of the mean field
model of composite fermions.


title: The Large Sieve Inequality for Integer Polynomial Amplitudes

abstract:
  We obtain a close to the best possible version of the large sieve inequality
with amplitudes given by the values of a polynomial with integer coefficients
of degree $\geq 2$.


title:
Optical and infrared properties of V1647 Orionis during the 2003-2006
  outburst. I The reflection nebula

abstract:
  Aims: The recent outburst of the young eruptive star V1647 Orionis has
produced a spectacular appearance of a new reflection nebula in Orion (McNeil's
nebula). We present an optical/near infrared investigation of McNeil's nebula.
This analysis is aimed at determining the morphology, temporal evolution and
nature of the nebula and its connection to the outburst.
  Method: We performed multi epoch B, V, R, I, z, and K imaging of McNeil's
nebula and V1647 Ori as well as K_S imaging polarimetry. The multiband imaging
allows us to reconstruct the extinction map inside the nebula. Through
polarimetric observations we attempt to disentangle the emission from the
nebula from that of the accretion disk around V1647 Ori. We also attempt to
resolve the small spatial scale structure of the illuminating source.
  Results: The energy distribution and temporal evolution of McNeil's nebula
mimic that of the illuminating source. The extinction map reveals a region of
higher extinction in the direction of V1647 Ori. Excluding foreground
extionction, the optical extinction due to McNeil's nebula in the direction of
V1647 Ori is A_V ~ 6.5 mag. The polarimetric measurement shows a compact high
polarization emission around V1647 Ori. The percentage of K_S band linear
polarization goes from 10 -- 20 %. The vectors are all well aligned with a
position angle of 90 +/- 9 degree East of North. This may correspond to the
orientation of a possible accretion disk around V1647 Ori. These findings
suggest that the appearance of McNeil's nebula is due to reflection of light by
pre-existing material in the surroundings of V1647 Ori. We also report on the
discovery of a new candidate brown dwarf or protostar in the vicinity of V1647
Ori as well as the presence of clumpy structure within HH 22A.


title: Minimal geodesics and topological entropy on T^2

abstract:
  Let (T^2, g) be a two-dimensional Riemannian torus. In this paper we prove
that the topological entropy of the geodesic flow restricted to the set of
initial conditions of minimal geodesics vanishes, independent of the choice of
the Riemannian metric.


title:
Simulation study of random sequential adsorption of mixtures on a
  triangular lattice

abstract:
  Random sequential adsorption of binary mixtures of extended objects on a
two-dimensional triangular lattice is studied numerically by means of Monte
Carlo simulations. The depositing objects are formed by self-avoiding random
walks on the lattice. We concentrate here on the influence of the symmetry
properties of the shapes on the kinetics of the deposition processes in
two-component mixtures. Approach to the jamming limit in the case of mixtures
is found to be exponential, of the form: $\theta(t) \sim
\theta_{jam}-\Delta\theta \exp (-t/\sigma),$ and the values of the parameter
$\sigma$ are determined by the order of symmetry of the less symmetric object
in the mixture. Depending on the local geometry of the objects making the
mixture, jamming coverage of a mixture can be either greater than both
single-component jamming coverages or it can be in between these values.
Results of the simulations for various fractional concentrations of the objects
in the mixture are also presented.


title: Disorder-Induced Order in Two-Component Bose-Einstein Condensates

abstract:
  We propose and analyze a general mechanism of disorder-induced order in
two-component Bose-Einstein condensates, analogous to corresponding effects
established for XY spin models. We show that a random Raman coupling induces a
relative phase of pi/2 between two BECs and that the effect is robust. We
demonstrate it in 1D, 2D and 3D at T=0 and present evidence that it persists at
small T>0. Applications to phase control in ultracold spinor condensates are
discussed.


title: A geometrical link between the circle and sexagesimal system

abstract:
  This paper presents a simple geometrical fact which could relate to the
history of mathematics and astronomy. This fact shows a natural link between
the circle and the multiples of 6 and it makes it possible to obtain a simple
representation of the 12 months of the year, the 24 hours of the day, the 30
days (average number) of the month and the 360 days (approximate number) of the
year, which brings us closer to the sexagesimal division of time. Moreover this
representation reminds one of the movement of the planets around a centre.
Using this fact one will be able also to find geometrically the principal
divisor of number 60, to represent numbers in base 60 with a kind of abacus or
calculation table and to make a division of the circle into 6 and 12 equal
parts. Afterwards one will be able to obtain a division in 360 unequal parts
but relatively close to one another, and the goal isn't precisely to obtain an
optimal division of the circle in 360 equal parts but to prove that the idea to
divide the circle in 360 equal parts can subsequently be suggested by these
geometrical facts that have been showed. In this article the author will not
answer the following questions: a) What is the origin of the sexagesimal
system? b) By which way could one manage to adopt the sexagesimal system
starting from the knowledge of the facts exposed in this article and starting
from the knowledge of the astronomical data? These questions could be treated,
using information of this article, by the readers or later on by the author.


title: Unparticles at heavy flavour scales: CP violating phenomena

abstract:
  Coupling the scale invariant unparticle sector to flavour physics and
assuming that it remains scale invariant we investigate its consequences in
heavy flavour physics. A drastic feature of unparticle physics is an unusual
phase leading to novel CP violating phenomena. We consider the CP asymmetry in
the leptonic decay B^+ -> tau^+ nu and the hadronic decay B_d -> D^+D^-, taking
into account constraints of branching ratios and time dependent CP asymmetries.
Generic plots are shown and it turns out that there exist parameters for which
the CP violation is maximal. A prediction of a large CP asymmetry in B_d ->
D^+D^- is difficult to achieve in other models without contradicting the
current data in other channels. The prediction of a CP asymmetry in leptonic
decays, such as B^+ -> tau^+ nu, is novel. We identify the CP compensating mode
due to the unparticles and show explicitly that it exactly cancels the CP
asymmetry of B^+ -> tau^+ nu as demanded by CPT invariance. Building up on
earlier works we investigate the breaking of scale invaricance, due to the
coupling to the Higgs and the size of the effects in the weak sector resorting
to a dimensional analysis. An enhancement is observed on the grounds of the
relevance of the unparticle interaction operator as compared to the weak
four-Fermi term.


title: Generic initial ideals and fibre products

abstract:
  We study the behavior of generic initial ideals with respect to fibre
products. In our main result we determine the generic initial ideal of the
fibre product with respect to the reverse lexicographic order. As an
application we compute the symmetric algebraic shifted complex of two disjoint
simplicial complexes as was conjectured by Kalai. This result is the symmetric
analogue of a theorem of Nevo who determined the exterior algebraic shifted
complex of two disjoint simplicial complexes as predicted by Kalai.


title:
Refined parameters and spectroscopic transit of the super-massive planet
  HD147506b

abstract:
  In this paper, we report a refined determination of the orbital parameters
and the detection of the Rossiter-McLaughlin effect of the recently discovered
transiting exoplanet HD147506b (HAT-P-2b). The large orbital eccentricity at
the short orbital period of this exoplanet is unexpected and is distinguishing
from other known transiting exoplanets. We performed high-precision radial
velocity spectroscopic observations of HD147506 (HAT-P-2) with the new
spectrograph SOPHIE, mounted on the 1.93 m telescope at the Haute-Provence
observatory (OHP). We obtained 63 new measurements, including 35 on May 14 and
20 on June 11, when the planet was transiting its parent star. The radial
velocity (RV) anomaly observed illustrates that HAT-P-2b orbital motion is set
in the same direction as its parent star spin. The sky-projected angle between
the normal of the orbital plane and the stellar spin axis, \lambda = 0.2 +12.2
-12.5 deg, is consistent with zero. The planetary and stellar radii were
re-determined, yielding R_p = 0.951 +0.039 -0.053 R_Jup, R_s = 1.416 +0.040
-0.062 R_Sun. The mass M_p = 8.62 +0.39 -0.55 M_Jup and radius of HAT-P-2b
indicate a density of 12.5 +2.6 -3.6 g cm^{-3}, suggesting an object in between
the known close-in planets with typical density of the order of 1 g cm^{-3},
and the very low-mass stars, with density greater than 50 g cm^{-3}.


title: First-order framework and domain-wall/brane-cosmology correspondence

abstract:
  We address the possibility of finding domain wall solutions from cosmological
solutions in brane cosmology. We find first-order equations for corresponding
cosmology/domain wall solutions induced on 3-branes. The quadratic term of
energy density in the induced Friedmann equation plays a non-standard role and
we discuss the way the standard cosmological and domain wall models are
recovered as the brane tension becomes large and show how they can be described
by four-dimensional supergravity action in such a limit. Finally, we show that
gravity on the 3-brane is locally localized as one moves away from the
two-dimensional domain walls living on the brane.


title: On the Equations of Nonstationary Transonic Gas Flows

abstract:
  The method of point transformation of the functions and variables for
construction of particular solutions of the Equations of Nonstationary
Transonic Gas Flows is used.


title: Midgap states and charge inhomogeneities in corrugated graphene

abstract:
  We study the changes induced by the effective gauge field due to ripples on
the low energy electronic structure of graphene. We show that zero energy
Landau levels will form, associated to the smooth deformation of the graphene
layer, when the height corrugation, $h$, and the length of the ripple, $l$, are
such that $h^2 / (l a) \gtrsim 1$, where $a$ is the lattice constant. The
existence of localized levels gives rise to a large compressibility at zero
energy, and to the enhancement of instabilities arising from electron-electron
interactions including electronic phase separation. The combined effect of the
ripples and an external magnetic field breaks the valley symmetry of graphene
leading to the possibility of valley selection.


title: Normal forms for parabolic Monge-Ampere equations

abstract:
  We find normal forms for parabolic Monge-Ampere equations. Of these, the most
general one holds for any equation admitting a complete integral. Moreover, we
explicitly give the determining equation for such integrals; restricted to the
analytic case, this equation is shown to have solutions. The other normal forms
exhaust the different classes of parabolic Monge-Ampere equations with symmetry
properties, namely, the existence of classical or nonholonomic intermediate
integrals. Our approach is based on the equivalence between parabolic
Monge-Ampere equations and particular distributions on a contact manifold, and
involves a classification of vector fields lying in the contact structure.
These are divided into three types and described in terms of the simplest ones
(characteristic fields of first order PDE's).


title:
Presence of dust with a UV bump in massive, star-forming galaxies at 1 <
  z < 2.5

abstract:
  Fundamental properties of the extinction curve, like the slope in the
rest-frame ultraviolet (UV) and the presence/absence of a broad absorption
excess centred at 2175 A (the UV bump), are investigated for a sample of 108
massive, star-forming galaxies at 1 < z < 2.5, selected from the FDF
Spectroscopic Survey, the K20 survey, and the GDDS. These characteristics are
constrained from a parametric description of the UV spectral energy
distribution (SED) of a galaxy, as enforced by combined stellar population and
radiative transfer models for different geometries, dust/stars configurations
and dust properties. In at least one third of the sample, there is a robust
evidence for extinction curves with at least a moderate UV bump. The presence
of the carriers of the UV bump is more evident in galaxies with UV SEDs
suffering from heavy reddening. We interpret these results as follows. The
sample objects possess different mixtures of dust grains and molecules
producing extinction curves in between the average ones of the Small and Large
Magellanic Cloud, where the UV bump is absent or modest, respectively. Most of
the dust embeds the UV-emitting stellar populations or is distributed out of
the galaxy mid-plane. Alternatively, even dust with a pronounced UV bump, as
for the average Milky-Way extinction curve, can be present and distributed in
the galaxy mid-plane. In this case, variations of the continuum scattering
albedo with wavelength or an age-dependent extinction are not sufficient to
explain the previous trend with reddening. Hence, additional extraplanar dust
has to be invoked. The data suggest that the carriers of the UV bump are
associated with intermediate-age stellar populations, while they survive in the
harshest UV-radiation fields owing to dust self-shielding. [abridged]


title: Symmetrised Characterisation of Noisy Quantum Processes

abstract:
  A major goal of developing high-precision control of many-body quantum
systems is to realise their potential as quantum computers. Probably the most
significant obstacle in this direction is the problem of "decoherence": the
extreme fragility of quantum systems to environmental noise and other control
limitations. The theory of fault-tolerant quantum error correction has shown
that quantum computation is possible even in the presence of decoherence
provided that the noise affecting the quantum system satisfies certain
well-defined theoretical conditions. However, existing methods for noise
characterisation have become intractable already for the systems that are
controlled in today's labs. In this paper we introduce a technique based on
symmetrisation that enables direct experimental characterisation of key
properties of the decoherence affecting a multi-body quantum system. Our method
reduces the number of experiments required by existing methods from exponential
to polynomial in the number of subsystems. We demonstrate the application of
this technique to the optimisation of control over nuclear spins in the solid
state.


title: Adiabatic elimination in quantum stochastic models

abstract:
  We consider a physical system with a coupling to bosonic reservoirs via a
quantum stochastic differential equation. We study the limit of this model as
the coupling strength tends to infinity. We show that in this limit the
solution to the quantum stochastic differential equation converges strongly to
the solution of a limit quantum stochastic differential equation. In the
limiting dynamics the excited states are removed and the ground states couple
directly to the reservoirs.


title:
The Dissociation of 8B in the Coulomb Field and the Validity of the CD
  Method

abstract:
  The GSI1, GSI2 (as well as the RIKEN2 and the corrected GSI2) measurements of
the Coulomb Dissociation (CD) of 8B are in good agreement with the most recent
Direct Capture (DC) 7Be(p,g)8B reaction measurement performed at Weizmann and
in agreement with the Seattle result. Yet it was claimed that the CD and DC
results are sufficiently different and need to be reconciled. We show that
these statements arise from a misunderstanding (as well as misrepresentation)
of CD experiments. We recall a similar strong statement questioning the
validity of the CD method due to an invoked large E2 component that was also
shown to arise from a misunderstanding of the CD method. In spite of the good
agreement between DC and CD data the slope of the astrophysical cross section
factor (S17) can not be extracted with high accuracy due to a discrepancy
between the recent DC data as well as a discrepancy of the three reports of the
GSI CD data. The slope is directly related to the d-wave component that
dominates at higher energies and must be subtracted from measured data to
extrapolate to zero energy. Hence the uncertainty of the measured slope leads
to an additional uncertainty of the extrapolated zero energy cross section
factor, S17(0). This uncertainty must be alleviated by future experiments to
allow a precise determination of S17(0), a goal that so far has not be achieved
in spite of strong statement(s) that appeared in the literature.


title: Dependence of ground state energy of classical n-vector spins on n

abstract:
  We study the ground state energy E_G(n) of N classical n-vector spins with
the hamiltonian H = - \sum_{i>j} J_ij S_i.S_j where S_i and S_j are n-vectors
and the coupling constants J_ij are arbitrary. We prove that E_G(n) is
independent of n for all n > n_{max}(N) = floor((sqrt(8N+1)-1) / 2) . We show
that this bound is the best possible. We also derive an upper bound for E_G(m)
in terms of E_G(n), for m<n. We obtain an upper bound on the frustration in the
system, as measured by F(n), which is defined to be (\sum_{i>j} |J_ij| +
E_G(n)) / (\sum_{i>j} |J_ij|). We describe a procedure for constructing a set
of J_ij's such that an arbitrary given state, {S_i}, is the ground state.


title: Did we observe the supernova shock breakout in GRB 060218?

abstract:
  If the early optical data of GRB 060218 up to 1e5 s are interpreted as the
black-body flux associated with the supernova shock breakout, we can derive
lower limits to the bolometric luminosity and energetics of this black-body
component. These limits are more severe for the very early data that imply
energetics of order of 1e51 erg. These values, puzzlingly large, are rather
independent of the assumed time profile of the emitting surface, provided that
the corresponding radius does not increase superluminally. Another concern is
the luminosity of the black-body component observed in the X-rays, that is
large and appears to be produced by an approximately constant temperature and a
surface area increasing only slowly in time. Although it has been suggested
that the long X-ray black-body duration is consistent with the supernova shock
breakout if anisotropy is assumed, the nearly constant emitting surface
requires some fine tuning, allowing and suggesting an alternative
interpretation, i.e. emission from late dissipation of the fireball bulk
kinetic energy. This in turn requires a small value of the bulk Lorentz factor.


title:
Characterizing Supernova Progenitors via the Metallicities of their Host
  Galaxies, from Poor Dwarfs to Rich Spirals

abstract:
  We investigate how the different types of supernovae are relatively affected
by the metallicity of their host galaxy. We match the SAI Supernova Catalog to
the SDSS-DR4 catalog of star-forming galaxies with measured metallicities.
These supernova host galaxies span a range of oxygen abundance from 12 +
log(O/H) = 7.9 to 9.3 (~ 0.1 to 2.7 solar) and a range in absolute magnitude
from MB = -15.2 to -22.2. To reduce the various observational biases, we select
a subsample of well-characterized supernovae in the redshift range from 0.01 to
0.04, which leaves us with 58 SN II, 19 Ib/c, and 38 Ia. We find strong
evidence that SN Ib/c are occurring in higher-metallicity host galaxies than SN
II, while we see no effect for SN Ia relative to SN II. We note some extreme
and interesting supernova-host pairs, including the metal-poor (~ 1/4 solar)
host of the recent SN Ia 2007bk, where the supernova was found well outside of
this dwarf galaxy. To extend the luminosity range of supernova hosts to even
fainter galaxies, we also match all the historical supernovae with z < 0.3 to
the SDSS-DR6 sky images, resulting in 1225 matches. This allows us to identify
some even more extreme cases, such as the recent SN Ic 2007bg, where the likely
host of this hypernova-like event has an absolute magnitude MB ~ -12, making it
one of the least-luminous supernova hosts ever observed. This low-luminosity
host is certain to be very metal poor (~ 1/20 solar), and therefore this
supernova is an excellent candidate for association with an off-axis GRB. The
two catalogs that we have constructed are available online and will be updated
regularly. Finally, we discuss various implications of our findings for
understanding supernova progenitors and their host galaxies.


title: Quantum entropic security and approximate quantum encryption

abstract:
  We present full generalisations of entropic security and entropic
indistinguishability to the quantum world where no assumption but a limit on
the knowledge of the adversary is made. This limit is quantified using the
quantum conditional min-entropy as introduced by Renato Renner. A proof of the
equivalence between the two security definitions is presented. We also provide
proofs of security for two different cyphers in this model and a proof for a
lower bound on the key length required by any such cypher. These cyphers
generalise existing schemes for approximate quantum encryption to the entropic
security model.


title: Mapping Cosmological Observables to the Dark Kinetics

abstract:
  We study systematically which features in the cosmic microwave background
(CMB) and large-scale structure (LSS) probe various inhomogeneous properties of
the dark sectors (including neutrinos, dark matter, and dark energy). We
stress, and quantify by simple formulas, that the primary CMB anisotropies are
very susceptible to the gravitational potentials during horizon entry, less at
recombination. The CMB thus allows us to scan \Phi+\Psi and the underlying dark
kinetics for all redshifts z~1-10^5. LSS, on the other hand, responds strongest
to \Phi at low redshifts. Dark perturbations are often parameterized by the
anisotropic stress and effective sound speed (stiffness). We find that the dark
anisotropic stress and stiffness influence the visible species at the
correspondingly early and late stages of horizon entry, and affect stronger
respectively the CMB and LSS. The CMB yet remains essential to probing the
stiff perturbations of light neutrinos and dark energy, detectable only during
horizon entry. The clustering of dark species and large propagation speed of
their inhomogeneities also map to distinctive features in the CMB and LSS. -Any
parameterization of the signatures of dark kinetics that assumes general
relativity can effectively accommodate any modified gravity (MG) that retains
the equivalence principle for the visible sectors. This implies that formally
the nonstandard structure growth or \Phi/\Psi ratio, while indicative, are not
definitive MG signatures. The definitive signatures of MG may include the
strong dependence of the apparent dark dynamics on visible species, its
superluminality, and the nonstandard phenomenology of gravitational waves.