title:
Proof of the Flohr-Grabow-Koehn conjectures for characters of
  logarithmic conformal field theory

abstract:
  In a recent paper Flohr, Grabow and Koehn conjectured that the characters of
the logarithmic conformal field theory c_{k,1}, of central charge
c=1-6(k-1)^2/k, admit fermionic representations labelled by the Lie algebra
D_k. In this note we provide a simple analytic proof of this conjecture.


title: Stability and hierarchy problems in string inspired braneworld scenarios

abstract:
  We generalise the RS braneworld model by taking into account a general
stringy bulk containing the scalar dilaton field and the two-form Kalb-Ramond
field, apart from gravity. Assuming small fluctuations around a RS background,
the back-reacted warp factor is obtained. It is shown that the fine tuning
problem in connection with the Higgs mass reappears in a new guise and the
effective modular potential fails to stabilise the braneworld.


title: Space Time Codes from Permutation Codes

abstract:
  A new class of space time codes with high performance is presented. The code
design utilizes tailor-made permutation codes, which are known to have large
minimal distances as spherical codes. A geometric connection between spherical
and space time codes has been used to translate them into the final space time
codes. Simulations demonstrate that the performance increases with the block
lengths, a result that has been conjectured already in previous work. Further,
the connection to permutation codes allows for moderate complex en-/decoding
algorithms.


title: Hybrid Chaplygin gas and phantom divide crossing

abstract:
  Hybrid Chaplygin gas model is put forward, in which the gases play the role
of dark energy. For this model the coincidence problem is greatly alleviated.
The effective equation of state of the dark energy may cross the phantom divide
$w=-1$. Furthermore, the crossing behaviour is decoupled from any gravity
theories. In the present model, $w<-1$ is only a transient behaviour. There is
a de Sitter attractor in the future infinity. Hence, the big rip singularity,
which often afflicts the models with matter whose effective equation of state
less than -1, is naturally disappear. There exist stable scaling solutions,
both at the early universe and the late universe. We discuss the perturbation
growth of this model. We find that the index is consistent with observations.


title:
Two-parameter Poisson-Dirichlet measures and reversible exchangeable
  fragmentation-coalescence processes

abstract:
  We show that for $0<\alpha<1$ and $\theta>-\alpha$, the Poisson-Dirichlet
distribution with parameter $(\alpha, \theta)$ is the unique reversible
distribution of a rather natural fragmentation-coalescence process. This
completes earlier results in the literature for certain split and merge
transformations and the parameter $\alpha =0$.


title:
On factorization of $q$-difference equation for continuous
  $q$-ultraspherical polynomials

abstract:
  We prove that a customary Sturm-Liouville form of second-order $q$-difference
equation for the continuous $q$-ultraspherical polynomials $C_n(x;\beta| q)$ of
Rogers can be written in a factorized form in terms of some explicitly defined
$q$-difference operator ${\mathcal D}_x^{\beta, q}$. This reveals the fact that
the continuous $q$-ultraspherical polynomials $C_n(x;\beta| q)$ are actually
governed by the $q$-difference equation ${\mathcal D}_x^{\beta, q} C_n(x;\beta|
q)= (q^{-n/2}+\beta q^{n/2}) C_n(x;\beta| q)$, which can be regarded as a
square root of the equation, obtained from its original form.


title: A second order minimality condition for the Mumford-Shah functional

abstract:
  A new necessary minimality condition for the Mumford-Shah functional is
derived by means of second order variations. It is expressed in terms of a sign
condition for a nonlocal quadratic form on $H^1_0(\Gamma)$, $\Gamma$ being a
submanifold of the regular part of the discontinuity set of the critical point.
Two equivalent formulations are provided: one in terms of the first eigenvalue
of a suitable compact operator, the other involving a sort of nonlocal capacity
of $\Gamma$. A sufficient condition for minimality is also deduced. Finally, an
explicit example is discussed, where a complete characterization of the domains
where the second variation is nonnegative can be given.


title: Theory of the tunneling spectroscopy of ferromagnetic superconductors

abstract:
  We study tunneling conductance in normal metal / insulator / ferromagnetic
superconductor junctions. The tunneling spectra show a clear difference between
spin-singlet s-wave pairing, spin-triplet opposite spin pairing and
spin-triplet equal spin pairing: These pairings exhibit, respectively, gap
struture, double peak structure and zero bias peak in the spectra. The obtained
result may serve as a tool for determining the pairing symmetry of
ferromagnetic superconductors.


title: A quantitative model for IcR product in d-wave Josephson junctions

abstract:
  We study theoretically the Josephson effect in d-wave superconductor /
diffusive normal metal /insulator/ diffusive normal metal/ d-wave
superconductor (D/DN/I/DN/D) junctions. This model is aimed to describe
practical junctions in high-$T_C$ cuprate superconductors, in which the product
of the critical Josephson current ($I_C$) and the normal state resistance ($R$)
(the so-called $I_{\rm C}R$ product) is very small compared to the prediction
of the standard theory. We show that the $I_{\rm C}R$ product in D/DN/I/DN/D
junctions can be much smaller than that in d-wave superconductor / insulator /
d-wave superconductor junctions and formulate the conditions necessary to
achieve large $I_{\rm C}R$ product in D/DN/I/DN/D junctions. The proposed
theory describes the behavior of $I_{\rm C}R$ products quantitatively in
high-$T_{\rm C}$ cuprate junctions.


title: The existence of superinvolutions

abstract:
  Superinvolutions on graded associative algebras constitute a source of Lie
and Jordan superalgebras. Graded versions of the classical Albert and
Albert-Riehm Theorems on the existence of superinvolutions are proven.
Surprisingly, the existence of superinvolutions of the first kind is a rare
phenomenon, as nontrivial central division superalgebras are never endowed with
this kind of superinvolutions.


title:
Variation of the Amati Relation with the Cosmological Redshift: a
  Selection Effect or an Evolution Effect?

abstract:
  Because of the limit in the number of gamma-ray bursts (GRBs) with available
redshifts and spectra, all current investigations on the correlation among GRB
variables use burst samples with redshifts that span a very large range. The
evolution and selection effects have thus been ignored, which might have
important influence on the results. In this Letter, we divide the 48
long-duration GRBs in Amati (2006, 2007) into four groups with redshift from
low to high, each group contains 12 GRBs. Then we fit each group with the Amati
relation $\log E_\iso = a + b \log E_\p$, and check if the parameters $a$ and
$b$ evolve with the GRB redshift. We find that $a$ and $b$ vary with the mean
redshift of the GRBs in each group systematically and significantly.
Monte-Carlo simulations show that there is only $\sim 4$ percent of chance that
the variation is caused by the selection effect arising from the fluence limit.
Hence, our results may indicate that GRBs evolve strongly with the cosmological
redshift.


title: Sums over geometries and improvements on the mean field approximation

abstract:
  The saddle points of a Lagrangian due to Efetov are analyzed. This Lagrangian
was originally proposed as a tool for calculating systematic corrections to the
Bethe approximation, a mean-field approximation which is important in
statistical mechanics, glasses, coding theory, and combinatorial optimization.
Detailed analysis shows that the trivial saddle point generates a sum over
geometries reminiscent of dynamically triangulated quantum gravity, which
suggests new possibilities to design sums over geometries for the specific
purpose of obtaining improved mean field approximations to $D$-dimensional
theories. In the case of the Efetov theory, the dominant geometries are locally
tree-like, and the sum over geometries diverges in a way that is similar to
quantum gravity's divergence when all topologies are included. Expertise from
the field of dynamically triangulated quantum gravity about sums over
geometries may be able to remedy these defects and fulfill the Efetov theory's
original promise. The other saddle points of the Efetov Lagrangian are also
analyzed; the Hessian at these points is nonnormal and pseudo-Hermitian, which
is unusual for bosonic theories. The standard formula for Gaussian integrals is
generalized to nonnormal kernels.


title: Hartree-Fock Approximation and Entanglement

abstract:
  The relation between the correlation energy and the entanglement is
analytically constructed for the Moshinsky's model of two coupled harmonic
oscillators. It turns out that the two quantities are far to be proportional,
even at very small couplings. A comparison is made also with the 2-point Ising
model.


title:
Observing high redshift galaxy clusters through lensing of the
  Ostriker-Vishniac effect

abstract:
  In this paper we study the possibility of detecting lensing signals in
high-resolution and high-sensitivity CMB experiments. At scales below 1 arcmin,
the CMB background is dominated by the Sunyaev-Zel'dovich effect in clusters
and by Ostriker-Vishniac effect distortions elsewhere. Assuming the
Sunyaev-Zel'dovich component in clusters can be removed, we focus on the
Ostriker-Vishniac effect and study the possibility of its detection while
paying special attention to contaminants, such as instrumental noise and point
sources. After designing an optimal filter for this particular lensing signal
we explore the signal-to-noise ratio for different scenarios varying the
resolution of the experiment, its sensitivity, and the level of contamination
due to point sources. Our results show that the next generation of experiments
should be able to do new and exciting science through the lensing effect of the
Ostriker-Vishniac background.


title:
Direct CP violation in $\bar{B}^0 \to \rho^0(\omega)\rho^0(\omega) \to
  \pi^+\pi^-\pi^+\pi^-$

abstract:
  We study the direct CP violation in $\bar{B}^0 \to
\rho^0(\omega)\rho^0(\omega) \to \pi^+\pi^-\pi^+\pi^-$ (with unpolarized
$\rho^0(\omega)$) via the $\rho-\omega$ mixing mechanism which causes a large
strong phase difference and consequently a large CP violating asymmetry when
the masses of the $\pi^+\pi^-$ pairs are in the vicinity of the $\omega$
resonance. Since there are two $\rho (\omega)$ mesons in the intermediate state
$\rho-\omega$ mixing contributes twice to the first order of isospin violation,
leading to an even larger CP violating asymmetry (could be 30% -- 50% larger)
than in the case where only one $\rho (\omega)$ meson is involved. The CP
violating asymmetry depends on the Cabibbo-Kobayashi-Maskawa (CKM) matrix
elements and the hadronic matrix elements. The factorization approach is
applied in the calculation of the hadronic matrix elements with the
nonfactorizable effects being included effectively in an effective parameter,
$N_c$. We give the constraint on the range of $N_c$ from the latest
experimental data for the branching ratios for $\bar{B}^0 \to\rho^0\rho^0$ and
$\bar{B}^0 \to\rho^+\rho^-$. We find that the CP violating asymmetry could be
very large (even more than 90% for some values of $N_c$). It is shown that the
sensitivity of the CP violating asymmetry to $N_c$ is large compared with its
smaller sensitivity to the CKM matrix elements. We also discuss the possibility
to remove the mod $(\pi)$ ambiguity in the determination of the CP violating
phase angle $\alpha$ through the measurement of the CP violating asymmetry in
the decay $\bar{B}^0\to \rho^0(\omega)\rho^0(\omega) \to \pi^+\pi^-\pi^+\pi^-$.


title:
Transverse Polarization of Lambda and Lambda-bar Hyperons in Quasireal
  Photoproduction

abstract:
  The HERMES experiment has measured the transverse polarization of Lambda and
Lambda-bar hyperons produced inclusively in quasireal photoproduction at a
positron beam energy of 27.6 GeV. The transverse polarization of the Lambda
hyperon is found to be positive while the observed Lambda-bar polarization is
compatible with zero. The transverse polarization values averaged over the
kinematic acceptance of HERMES are 0.078 +/- 0.006(stat) +/- 0.012(syst) and
-0.025 +/- 0.015(stat) +/- 0.018(syst) for Lambda and Lambda-bar hyperons,
respectively. The dependences of Lambda and Lambda-bar polarizations on the
fraction $\zeta$ of the beam's light-cone momentum carried by the hyperon and
on the hyperon's transverse momentum $p_T$ were investigated. The measured
Lambda polarization rises linearly with $p_T$ and exhibits a different behavior
for low and high values of $\zeta$, which approximately correspond to the
backward and forward regions in the center-of-mass frame of the $\gamma^*N$
reaction.


title: A study of global monopole in Lyra geometry

abstract:
  A class of exact static solution around a global monopole resulting from the
breaking of a global S0(3) symmetry is obtained in the context of Lyra
geometry. Our solution is shown to possess an interesting feature like
wormholes space-time. It has been shown that the global monopole exerts no
gravitational force on surrounding non-relativistic matter.


title:
Opposite magnetic polarity of two photospheric lines in single spectrum
  of the quiet Sun

abstract:
  We study the structure of the photospheric magnetic field of the quiet Sun by
investigating weak spectro-polarimetric signals. We took a sequence of Stokes
spectra of the Fe I 630.15 nm and 630.25 nm lines in a region of quiet Sun near
the disk center, using the POLIS spectro-polarimeter at the German VTT on
Tenerife. The line cores of these two lines form at different heights in the
atmosphere. The 3$\sigma$ noise level of the data is about 1.8 $\times 10^{-3}
I_{c}$. We present co-temporal and co-spatial Stokes-$V$ profiles of the Fe I
630 nm line pair, where the two lines show opposite polarities in a single
spectrum. We compute synthetic line profiles and reproduce these spectra with a
two-component model atmosphere: a non-magnetic component and a magnetic
component. The magnetic component consists of two magnetic layers with opposite
polarity: the upper one moves upwards while the lower one moves downward.
In-between, there is a region of enhanced temperature. The Stokes-$V$ line pair
of opposite polarity in a single spectrum can be understood as a magnetic
reconnection event in the solar photosphere. We demonstrate that such a
scenario is realistic, but the solution may not be unique.


title:
Hidden Symmetry, Excitonic Transitions and Two-Dimensional Kane's
  Exciton in the Quantum Well

abstract:
  In this article it is shown that, Sommerfeld's coefficients for excitonic
transitions in quantum wells are determined only with the principle quantum
number within the framework of two-dimensional Coulomb potential. This is a
consequence of hidden symmetry of two-dimensional Coulomb problem, conditioned
by the existence of two-dimensional analog of the Runge-Lentz vector. For the
narrow gap semiconductor quantum well with the non-parabolic dispersion law of
electron and hole in the two-band Kane model it is shown that two-dimensional
excitonic states are described in the frames of an analog of Klein-Gordon
equation with the two-dimensional Coulomb potential. The non-stability of the
ground state of the two-dimensional Kane's exciton is show.


title: Scanning magnetoresistance microscopy of atom chips

abstract:
  Surface based geometries of microfabricated wires or patterned magnetic films
can be used to magnetically trap and manipulate ultracold neutral atoms or
Bose-Einstein condensates. We investigate the magnetic properties of such atom
chips using a scanning magnetoresistive (MR) microscope with high spatial
resolution and high field sensitivity. We show that MR sensors are ideally
suited to observe small variations of the magnetic field caused by
imperfections in the wires or magnetic materials which ultimately lead to
fragmentation of ultracold atom clouds. Measurements are also provided for the
magnetic field produced by a thin current-carrying wire with small geometric
modulations along the edge. Comparisons of our measurements with a full numeric
calculation of the current flow in the wire and the subsequent magnetic field
show excellent agreement. Our results highlight the use of scanning MR
microscopy as a convenient and powerful technique for precisely characterizing
the magnetic fields produced near the surface of atom chips.


title:
Inverse Geometric Approach to the Simulation of the Circular Growth. The
  Case of Multicellular Tumor Spheroids

abstract:
  We demonstrate the power of the genetic algorithms to construct the cellular
automata model simulating the growth of 2-dimensional close-to-circular
clusters revealing the desired properties, such as the growth rate and, at the
same time, the fractal behavior of their contours. The possible application of
the approach in the field of tumor modeling is outlined.


title:
Element-resolved x-ray ferrimagnetic and ferromagnetic resonance
  spectroscopy

abstract:
  We report on the measurement of element-specific magnetic resonance spectra
at gigahertz frequencies using x-ray magnetic circular dichroism (XMCD). We
investigate the ferrimagnetic precession of Gd and Fe ions in Gd-substituted
Yttrium Iron Garnet, showing that the resonant field and linewidth of Gd
precisely coincide with Fe up to the nonlinear regime of parametric
excitations. The opposite sign of the Gd x-ray magnetic resonance signal with
respect to Fe is consistent with dynamic antiferromagnetic alignment of the two
ionic species. Further, we investigate a bilayer metal film,
Ni$_{80}$Fe$_{20}$(5 nm)/Ni(50 nm), where the coupled resonance modes of Ni and
Ni$_{80}$Fe$_{20}$ are separately resolved, revealing shifts in the resonance
fields of individual layers but no mutual driving effects. Energy-dependent
dynamic XMCD measurements are introduced, combining x-ray absorption and
magnetic resonance spectroscopies.


title: Non static cosmic strings in Lyra geometry

abstract:
  The gravitational field of both local and global non static cosmic strings in
the context of Lyra geometry are investigated. Local strings are characterized
by having an energy momentum tensor whose only non null components are $T_{tt}
= T_{zz}$ . As linearized Einstein equations are formally analogous to the
Maxwell equations, the exterior solution does not depend on the radial
distribution of the source and hence a Dirac d function was used to approximate
the radial distribution of the energy momentum tensor for a local cosmic string
along the z-axis: $T_{ab} = \delta(x) \delta(y)diag (\sigma, 0, 0, \sigma) $,
$\sigma $being the energy density of the string [A.Vilenkin.
Phys.Rep.(1985)121,263]. For a global string, the energy momentum tensor
components are calculated from the action density for a complex scalar field y
along with a Maxican hat potential. The gravitational field of the global
string is shown to be attractive in nature.


title:
Algorithm for Evaluation of the Interval Power Function of Unconstrained
  Arguments

abstract:
  We describe an algorithm for evaluation of the interval extension of the
power function of variables x and y given by the expression x^y. Our algorithm
reduces the general case to the case of non-negative bases.


title:
A QMA-Complete Translationally Invariant Hamiltonian Problem and the
  Complexity of Finding Ground State Energies in Physical Systems

abstract:
  Here we present a problem related to the local Hamiltonian problem
(identifying whether the ground state energy falls within one of two ranges)
which is restricted to being translationally invariant. We prove that for
problems with a fixed local dimension and O(\log(N))-body local terms, or local
dimension N and 2-body terms, there are instances of the problem which are
QMA-complete. We discuss the implications for the computational complexity of
finding ground states of these systems, and hence for any classical
approximation techniques that one could apply including DMRG, Matrix Product
States and MERA. One important example is a 1D lattice of bosons with
nearest-neighbor hopping at constant filling fraction i.e. a generalization of
the Bose-Hubbard model.


title: Charge redistribution at YBa2Cu3O7-metal interfaces

abstract:
  Charge redistribution at interfaces is crucial for electronic applications of
high-Tc superconductors, since the band structure is modified on a local scale.
We address the normal-state electronic structure of YBa2Cu3O7 (YBCO) at an
YBCO-metal contact by first principles calculations for prototypical interface
configurations. We derive quantitative results for the intrinsic doping of the
superconducting CuO2 planes due to the metal contact. Our findings can be
explained in terms of a band-bending mechanism, complemented by local screening
effects. We determine a net charge transfer of 0.09 to 0.13 electrons in favour
of the intraplane Cu sites, depending on the interface orientation.


title: Complex data processing: fast wavelet analysis on the sphere

abstract:
  In the general context of complex data processing, this paper reviews a
recent practical approach to the continuous wavelet formalism on the sphere.
This formalism notably yields a correspondence principle which relates wavelets
on the plane and on the sphere. Two fast algorithms are also presented for the
analysis of signals on the sphere with steerable wavelets.


title:
Surgery formula for Seiberg--Witten invariants of negative definite
  plumbed 3-manifolds

abstract:
  We derive a cut-and-paste surgery formula of Seiberg--Witten invariants for
negative definite plumbed rational homology 3-spheres. It is similar to (and
motivated by) Okuma's recursion formula [arXiv:math.AG/0610464, 4.5] targeting
analytic invariants of splice quotient singularities. The two formulas combined
provide automatically a proof of the equivariant version
[arXiv:math.AG/0310084, 5.2(b)] of the `Seiberg--Witten invariant conjecture'
[arXiv:math.AG/0111298] for these singularities.


title: Enhanced spin-orbit scattering length in narrow Al_xGa_{1-x}N/GaN wires

abstract:
  The magnetotransport in a set of identical parallel AlGaN/GaN quantum wire
structures was investigated. The width of the wires was ranging between 1110 nm
and 340 nm. For all sets of wires clear Shubnikov--de Haas oscillations are
observed. We find that the electron concentration and mobility is approximately
the same for all wires, confirming that the electron gas in the AlGaN/GaN
heterostructure is not deteriorated by the fabrication procedure of the wire
structures. For the wider quantum wires the weak antilocalization effect is
clearly observed, indicating the presence of spin-orbit coupling. For narrow
quantum wires with an effective electrical width below 250 nm the weak
antilocalization effect is suppressed. By comparing the experimental data to a
theoretical model for quasi one-dimensional structures we come to the
conclusion that the spin-orbit scattering length is enhanced in narrow wires.


title: Fold cobordisms and stable homotopy groups

abstract:
  We show that the cobordism groups of negative codimensional folds maps
contain direct sums of stable homotopy groups of Thom spaces of vector bundles
like the circle and the infinite dimensional projective space. We give
geometrical invariants which detect these direct summands.


title: The causal boundary of product spacetimes

abstract:
  The new formulation of the causal completion of spacetimes suggested in [1],
and modified later in [2], is tested by computing the causal boundary for
product spacetimes of a Lorentz interval and a Riemannian manifold. This is
particularized for two important families of spacetimes, conformal to the
previous ones: (standard) static spacetimes and Generalized Robertson-Walker
spacetimes. As consequence, it is shown that this new approach essentially
reproduces the structure of the conformal boundary for multiple classical
spacetimes: Reissner-Nordstrom (including Schwarzschild), Anti-de Sitter, Taub
and standard cosmological models as de Sitter and Einstein Universe.


title: Effects of turbulent diffusion on the chemistry of diffuse clouds

abstract:
  Aims. We probe the effect of turbulent diffusion on the chemistry at the
interface between a cold neutral medium (CNM) cloudlet and the warm neutral
medium (WNM). Methods. We perform moving grid, multifluid, 1D, hydrodynamical
simulations with chemistry including thermal and chemical diffusion. The
diffusion coefficients are enhanced to account for turbulent diffusion. We
post-process the steady-states of our simulations with a crude model of
radiative transfer to compute line profiles. Results. Turbulent diffusion
spreads out the transition region between the CNM and the WNM. We find that the
CNM slightly expands and heats up: its CH and H$_2$ content decreases due to
the lower density. The change of physical conditions and diffusive transport
increase the H$^+$ content in the CNM which results in increased OH and H$_2$O.
Diffusion transports some CO out of the CNM. It also brings H$_2$ into contact
with the warm gas with enhanced production of CH$^+$, H$_3^+$, OH and H$_2$O at
the interface. O lines are sensitive to the spread of the thermal profile in
the intermediate region between the CNM and the WNM. Enhanced molecular content
at the interface of the cloud broadens the molecular line profiles and helps
exciting transitions of intermediate energy. The relative molecular yield are
found higher for bigger clouds. Conclusions. Turbulent diffusion can be the
source of additional molecular production and should be included in chemical
models of the interstellar medium (ISM). It also is a good candidate for the
interpretation of observational problems such as warm H$_2$, CH$^+$ formation
and presence of H$_3^+$.


title: Semi-Regular Variables in the Solar Neighbourhood

abstract:
  Period-luminosity sequences have been shown to exist among the Semi-Regular
Variables (SRVs) in the Magellanic Clouds (Wood et al, 1999), the Bulge of the
Milky Way galaxy (Glass & Schultheis, 2003) and elsewhere. Using modern period
and revised Hipparcos parallax data, this paper demonstrates that they also
appear among the M-giant SRVs of the Solar Neighbourhood. Their distribution in
the K, log P diagram resembles that of Bulge stars more closely than those in
the Magellanic Clouds. The prevalence of mass-loss among local M-type SRVs and
its dependence on period and spectral sub-type are also discussed. K -- [12], a
measure of circumstellar dust emission, increases clearly with V amplitude, M
giant sub-type and log P.


title: Uniformly continuous maps between ends of R-trees

abstract:
  There is a well-known correspondence between infinite trees and ultrametric
spaces which can be interpreted as an equivalence of categories and comes from
considering the end space of the tree.
  In this equivalence, uniformly continuous maps between the end spaces are
translated to some classes of coarse maps (or even classes of metrically proper
lipschitz maps) between the trees.


title:
Cosmological Casimir effect with maximum planckian momentum and
  accelerating universe

abstract:
  We develop here a mechanism that, without making use of a cosmological
constant, reproduces an accelerating universe. This is done by taking into
account Casimir vacuum energy density, assuming that the underlying theory
allows a maximum momentum, that turns out to be the leading contribution term
to Einstein equations in a large expanding FRW universe. As stated in numerous
quantum gravity studies, we postulate that maximum momentum is related to the
existence of the Planck length as a fundamental length. This insight, together
with the assumption of a Planck scale correction to the energy/momentum
dispersion-relation on a FRW background, is used here to calculate Casimir
vacuum energy. We show that, under these hypothesis, an accelerated universe
expansion is obtained. As last step we analyze the compatibility of the
resulting model with experimental data, writing down the equation of state for
Casimir energy and pressure and observing that this equation of state belongs
to a class of models that naturally fits cosmological observations. We
emphasize that our result relies, once a fundamental length is introduced in
Casimir effect, just on general arguments thus it is independent on an explicit
form of the energy-momentum dispersion relation.


title:
Deviations from Tri-bimaximal Neutrino Mixing in Type-II Seesaw and
  Leptogenesis

abstract:
  Current experimental data allow the zero value for one neutrino mass, either
m_1 = 0 or m_3 = 0. This observation implies that a realistic neutrino mass
texture can be established by starting from the limit (a) m_1 = m_2 = 0 and m_3
\neq 0 or (b) m_1 = m_2 \neq 0 and m_3 = 0. In both cases, we may introduce a
particular perturbation which ensures the resultant neutrino mixing matrix to
be the tri-bimaximal mixing pattern or its viable variations with all entries
being formed from small integers and their square roots. We find that it is
natural to incorporate this kind of neutrino mass matrix in the minimal Type-II
seesaw model with only one heavy right-handed Majorana neutrino N in addition
to the SU(2)_L Higgs triplet \Delta_L. We show that it is possible to account
for the cosmological baryon number asymmetry in the m_3 =0 case via thermal
leptogenesis, in which the one-loop vertex correction to N decays is mediated
by \Delta_L and the CP-violating asymmetry of N decays is attributed to the
electron flavor.


title: Supersonic radiatively cooled rotating flows and jets in the laboratory

abstract:
  The first laboratory astrophysics experiments to produce a radiatively cooled
plasma jet with dynamically significant angular momentum are discussed. A new
configuration of wire array z-pinch, the twisted conical wire array, is used to
produce convergent plasma flows each rotating about the central axis. Collision
of the flows produces a standing shock and jet that each have supersonic
azimuthal velocities. By varying the twist angle of the array, the rotation
velocity of the system can be controlled, with jet rotation velocities reaching
~20% of the propagation velocity.


title:
Geometrical properties of local dynamics in Hamiltonian systems: the
  Generalized Alignment Index (GALI) method

abstract:
  We investigate the detailed dynamics of multidimensional Hamiltonian systems
by studying the evolution of volume elements formed by unit deviation vectors
about their orbits. The behavior of these volumes is strongly influenced by the
regular or chaotic nature of the motion, the number of deviation vectors, their
linear (in)dependence and the spectrum of Lyapunov exponents. The different
time evolution of these volumes can be used to identify rapidly and efficiently
the nature of the dynamics, leading to the introduction of quantities that
clearly distinguish between chaotic behavior and quasiperiodic motion on
$N$-dimensional tori. More specifically we introduce the Generalized Alignment
Index of order $k$ (GALI$_k$) as the volume of a generalized parallelepiped,
whose edges are $k$ initially linearly independent unit deviation vectors from
the studied orbit whose magnitude is normalized to unity at every time step.
The GALI$_k$ is a generalization of the Smaller Alignment Index (SALI)
(GALI$_2$ $\propto$ SALI). However, GALI$_k$ provides significantly more
detailed information on the local dynamics, allows for a faster and clearer
distinction between order and chaos than SALI and works even in cases where the
SALI method is inconclusive.

categories: nlin.CD math-ph math.DS math.MP math.SG physics.acc-ph physics.class-ph physics.comp-ph


title:
How to clean a dirty floor: Probabilistic potential theory and the
  Dobrushin uniqueness theorem

abstract:
  Motivated by the Dobrushin uniqueness theorem in statistical mechanics, we
consider the following situation: Let \alpha be a nonnegative matrix over a
finite or countably infinite index set X, and define the "cleaning operators"
\beta_h = I_{1-h} + I_h \alpha for h: X \to [0,1] (here I_f denotes the
diagonal matrix with entries f). We ask: For which "cleaning sequences" h_1,
h_2, ... do we have c \beta_{h_1} ... \beta_{h_n} \to 0 for a suitable class of
"dirt vectors" c? We show, under a modest condition on \alpha, that this occurs
whenever \sum_i h_i = \infty everywhere on X. More generally, we analyze the
cleaning of subsets \Lambda \subseteq X and the final distribution of dirt on
the complement of \Lambda. We show that when supp(h_i) \subseteq \Lambda with
\sum_i h_i = \infty everywhere on \Lambda, the operators \beta_{h_1} ...
\beta_{h_n} converge as n \to \infty to the "balayage operator" \Pi_\Lambda =
\sum_{k=0}^\infty (I_\Lambda \alpha)^k I_{\Lambda^c). These results are
obtained in two ways: by a fairly simple matrix formalism, and by a more
powerful tree formalism that corresponds to working with formal power series in
which the matrix elements of \alpha are treated as noncommuting indeterminates.


title:
Experimenting with recursive queries in database and logic programming
  systems

abstract:
  This paper considers the problem of reasoning on massive amounts of (possibly
distributed) data. Presently, existing proposals show some limitations: {\em
(i)} the quantity of data that can be handled contemporarily is limited, due to
the fact that reasoning is generally carried out in main-memory; {\em (ii)} the
interaction with external (and independent) DBMSs is not trivial and, in
several cases, not allowed at all; {\em (iii)} the efficiency of present
implementations is still not sufficient for their utilization in complex
reasoning tasks involving massive amounts of data. This paper provides a
contribution in this setting; it presents a new system, called DLV$^{DB}$,
which aims to solve these problems. Moreover, the paper reports the results of
a thorough experimental analysis we have carried out for comparing our system
with several state-of-the-art systems (both logic and databases) on some
classical deductive problems; the other tested systems are: LDL++, XSB, Smodels
and three top-level commercial DBMSs. DLV$^{DB}$ significantly outperforms even
the commercial Database Systems on recursive queries. To appear in Theory and
Practice of Logic Programming (TPLP)


title: Cosmological applications of a wavelet analysis on the sphere

abstract:
  The cosmic microwave background (CMB) is a relic radiation of the Big Bang
and as such it contains a wealth of cosmological information. Statistical
analyses of the CMB, in conjunction with other cosmological observables,
represent some of the most powerful techniques available to cosmologists for
placing strong constraints on the cosmological parameters that describe the
origin, content and evolution of the Universe. The last decade has witnessed
the introduction of wavelet analyses in cosmology and, in particular, their
application to the CMB. We review here spherical wavelet analyses of the CMB
that test the standard cosmological concordance model. The assumption that the
temperature anisotropies of the CMB are a realisation of a statistically
isotropic Gaussian random field on the sphere is questioned. Deviations from
both statistical isotropy and Gaussianity are detected in the reviewed works,
suggesting more exotic cosmological models may be required to explain our
Universe. We also review spherical wavelet analyses that independently provide
evidence for dark energy, an exotic component of our Universe of which we know
very little currently. The effectiveness of accounting correctly for the
geometry of the sphere in the wavelet analysis of full-sky CMB data is
demonstrated by the highly significant detections of physical processes and
effects that are made in these reviewed works.


title:
Mass Loss and Evolution of Stars and Star Clusters: a Personal
  Historical Perspective

abstract:
  The development and progress of the studies of winds and mass loss from hot
stars, from about 1965 up to now, is discussed in a personal historical
perspective. The present state of knowledge about stellar winds, based on
papers presented at this workshop, is described. About ten years ago the
mechanisms of the winds were reasonably well understood, the mass loss rates
were known, and the predictions of stellar evolution theory with mass loss
agreed with observations. However, recent studies especially those based on
FUSE observations, have resulted in a significant reduction of the mass loss
rates, that disagrees with predictions from radiation driven wind models. The
situation is discussed and future studies that can clarify the situation are
suggested.
  I also discuss what is known about the dissolution of star clusters in
different environments. The dissolution time can be derived from the mass and
age distributions of cluster samples. The resulting dissolution times of
clusters in the solar neighborhood (SN) and in interacting galaxies are shorter
than predicted by two-body relaxation of clusters in a tidal field. Encounters
with giant molecular clouds can explain the fate of clusters in the SN and are
the most likely cause of the short lifetime of clusters in interacting
galaxies.


title: New Form of the T-Duality Due to the Stability of a Compact Dimension

abstract:
  We study behaviors of a compact dimension and the $T$-duality, in the
presence of the wrapped closed bosonic strings. When the closed strings
interact and form another system of strings, the radius of compactification
increases. This modifies the $T$-duality, which we call it as $T$-duality-like.
Some effects of the $T$-duality-like will be studied.


title:
van der Waals-like phase separation instability of a driven granular gas
  in three dimensions

abstract:
  We show that the van der Waals-like phase separation instability of a driven
granular gas at zero gravity, previously investigated in two-dimensional
settings, persists in three dimensions. We consider a monodisperse granular gas
driven by a thermal wall of a three-dimensional rectangular container at zero
gravity. The basic steady state of this system, as described by granular
hydrodynamic equations, involves a denser and colder layer of granulate located
at the wall opposite to the driving wall. When the inelastic energy loss is
sufficiently high, the driven granular gas exhibits, in some range of average
densities, negative compressibility in the directions parallel to the driving
wall. When the lateral dimensions of the container are sufficiently large, the
negative compressibility causes spontaneous symmetry breaking of the basic
steady state and a phase separation instability. Event-driven molecular
dynamics simulations confirm and complement our theoretical predictions.


title:
Neutrino transport and hydrodynamic stability of rotating proto-neutron
  stars

abstract:
  We consider stability of differentially rotating non-magnetic proto-neutron
stars. When neutrino transport is efficient, the star can be subject to a
diffusive instability that can occur even in the convectively stable region.
The instability arises on the time-scale comparable to the time-scale of
thermal diffusion. Hydrodynamic motions driven by the instability can lead to
anisotropy in the neutrino flux since the instability is suppressed near the
equator and rotation axis.


title: Severi varieties and self rational maps of K3 surfaces

abstract:
  Self-rational maps of generic algebraic K3 surfaces are conjectured to be
trivial. We relate this conjecture to a conjecture concerning the
irreducibility of the universal Severi varieties parametrizing nodal curves of
given genus and degree lying on some K3 surface. We also establish a number of
numerical constraints satisfied by such non trivial rational maps, that is of
topological degree >1.


title: A dual lagrangian for non-Abelian tensor gauge fields

abstract:
  For non-Abelian tensor gauge fields of the lower rank we have found an
alternative expression for the field strength tensors, which transform
homogeneously with respect to the complementary gauge transformations and allow
us to construct the dual Lagrangian.


title: Graphene Spin Valve Devices

abstract:
  Graphene - a single atomic layer of graphite - is a recently-found
two-dimensional form of carbon, which exhibits high crystal quality and
ballistic electron transport at room temperature. Soft magnetic NiFe electrodes
have been used to inject polarized spins into graphene and a 10% change in
resistance has been observed as the electrodes switch from the parallel to the
antiparallel state. This coupled with the fact that a field effect electrode
can modulate the conductivity of these graphene films makes them exciting
potential candidates for spin electronic devices.


title: XMM-Newton observations of Nova Sgr 1998

abstract:
  We report on X-ray observations of Nova Sagittarius 1998 (V4633 Sgr),
performed with XMM-Newton at three different epochs, 934, 1083 and 1265 days
after discovery. The nova was detected with the EPIC cameras at all three
epochs, with emission spanning the whole energy range from 0.2 to 10 keV.
  The X-ray spectra do not change significantly at the different epochs, and
are well fitted for the first and third observations with a multi-temperature
optically thin thermal plasma, while lower statistics in the second
observations lead to a poorer fit. The thermal plasma emission is most probably
originated in the shock heated ejecta, with chemical composition similar to
that of a CO nova. However, we can not completely rule out reestablished
accretion as the origin of the emission. We also obtain upper limits for the
temperature and luminosity of a potential white dwarf atmospheric component,
and conclude that hydrogen burning had already turned-off by the time of our
observations.


title: The Goldberger-Miyazawa-Oehme sum rule revisited

abstract:
  The Goldberger-Miyazawa-Oehme sum rule is used to extract the pion-nucleon
coupling constant from experimental $\pi$N information. Chiral perturbation
theory is exploited in relating the pionic hydrogen s-wave level shift and
width results to the appropriate scattering lengths. The deduced value for the
coupling is $f^2 = 0.075 \pm 0.002$, where the largest source of uncertainty is
the determination of the s-wave $\pi^- p$ scattering length from the atomic
level shift measurement.


title: Detection of superhumps in the VY Scl-type nova-like variable KR Aur

abstract:
  We report on detection of negative superhumps in KR Aur which is the
representative member of the VY Scl stars. The observations were obtained with
the multi-channel photometer during 107 h. The analysis of the data clearly
revealed brightness variations with a period of 3.771 +/- 0.005 h. This is 3.5
per cent less than the orbital period, suggesting it is a negative superhump.
Negative superhumps in VY Scl stars are widely spread. The discovery of
powerful soft X-rays from V751 Cyg demonstrates that VY Scl stars may contain
white dwarfs, at which nuclear burning of the accreted material occur. If this
suspicion is correct, we then can suppose that the powerful radiation emerging
from the white dwarf may cause the tilt of the accretion disk to the orbital
plane, and its retrograde precession may produce negative superhumps in VY Scl
stars.


title: Grafting hyperbolic metrics and Eisenstein series

abstract:
  The family hyperbolic metric for the plumbing variety $\{zw=t\}$ and the non
holomorphic Eisenstein series $E(\zeta;2)$ are combined to provide an explicit
expansion for the hyperbolic metrics for degenerating families of Riemann
surfaces. Applications include an asymptotic expansion for the Weil-Petersson
metric and a local form of symplectic reduction.


title:
Zipf's law and city sizes: A short tutorial review on multiplicative
  processes in urban growth

abstract:
  We address the role of multiplicative stochastic processes in modeling the
occurrence of power-law city size distributions. As an explanation of the
result of Zipf's rank analysis, Simon's model is presented in a mathematically
elementary way, with a thorough discussion of the involved hypotheses. Emphasis
is put on the flexibility of the model, as to its possible extensions and the
relaxation of some strong assumptions. We point out some open problems
regarding the prediction of the detailed shape of Zipf's rank plots, which may
be tackled by means of such extensions.


title: The origin of X-ray emission from T Tauri stars

abstract:
  Several aspects concerning the origin of the very strong X-ray activity of T
Tauri Stars (TTS) are still not well understood. Important new insight came
recently from the Chandra Orion Ultradeep Project (COUP), a unique 10-day long
Chandra observation of the Orion Nebula Cluster, and the XMM-Newton Extended
Survey of the Taurus Molecular Cloud (XEST). Based mainly on the results of
these two large projects, I will discuss our current knowledge about the
location of the X-ray emitting structures in TTS, the nature of their coronal
magnetic fields, inferences for pre-main-sequence magnetic dynamos, and the
relation between accretion processes and X-ray emission.


title:
Force induced conformational transition in a system of interacting stiff
  polymer: Application to unfolding

abstract:
  We consider a stiff polymer chain in poor solvent and apply a force at one
end of the chain. We find that by varying the stiffness parameter, polymer
undergoes a transition from the globule state to the folded like state. The
conformation of folded state mimics the $\beta$-sheet as seen in titin
molecule. Using exact enumeration technique, we study the extension-force and
force-temperature diagrams of such a system. Force-temperature diagram shows
the re-entrance behaviour for flexible chain. However, for stiff chain this
re-entrance behaviour is absent and there is an enhancement in
$\theta$-temperature with the rise of stiffness. We further propose that the
internal information about the frozen structure of polymer can be read from the
distribution of end-to-end distance which shows saw-tooth like behaviour.


title: A Critical Phenomenon in Solitonic Ising Chains

abstract:
  We discuss a phase transition of the second order taking place in non-local
1D Ising chains generated by specific infinite soliton solutions of the KdV and
BKP equations.

categories: cond-mat.stat-mech math-ph math.MP nlin.SI


title:
A new chaotic attractor in a basic multi-strain epidemiological model
  with temporary cross-immunity

abstract:
  An epidemic multi-strain model with temporary cross-immunity shows chaos,
even in a previously unexpected parameter region. Especially dengue fever
models with strong enhanced infectivity on secondary infection have previously
shown deterministic chaos motivated by experimental findings of
antibody-dependent-enhancement (ADE). Including temporary cross-immunity in
such models, which is common knowledge among field researchers in dengue, we
find a deterministically chaotic attractor in the more realistic parameter
region of reduced infectivity on secondary infection (''inverse ADE'' parameter
region). This is realistic for dengue fever since on second infection people
are more likely to be hospitalized, hence do not contribute to the force of
infection as much as people with first infection.
  Our finding has wider implications beyond dengue in any multi-strain
epidemiological systems with altered infectivity upon secondary infection,
since we can relax the condition of rather high infectivity on secondary
infection previously required for deterministic chaos. For dengue the finding
of wide ranges of chaotic attractors open new ways to analysis of existing data
sets.


title: Effects of Eye-phase in DNA unzipping

abstract:
  The onset of an "eye-phase" and its role during the DNA unzipping is studied
when a force is applied to the interior of the chain. The directionality of the
hydrogen bond introduced here shows oscillations in force-extension curve
similar to a "saw-tooth" kind of oscillations seen in the protein unfolding
experiments. The effects of intermediates (hairpins) and stacking energies on
the melting profile have also been discussed.


title:
The contact process in disordered and periodic binary two-dimensional
  lattices

abstract:
  The critical behavior of the contact process in disordered and periodic
binary 2d-lattices is investigated numerically by means of Monte Carlo
simulations as well as via an analytical approximation and standard mean field
theory. Phase-separation lines calculated numerically are found to agree well
with analytical predictions around the homogeneous point. For the disordered
case, values of static scaling exponents obtained via quasi-stationary
simulations are found to change with disorder strength. In particular, the
finite-size scaling exponent of the density of infected sites approaches a
value consistent with the existence of an infinite-randomness fixed point as
conjectured before for the 2d disordered CP. At the same time, both dynamical
and static scaling exponents are found to coincide with the values established
for the homogeneous case thus confirming that the contact process in a
heterogeneous environment belongs to the directed percolation universality
class.


title: Computing modular polynomials in quasi-linear time

abstract:
  We analyse and compare the complexity of several algorithms for computing
modular polynomials. We show that an algorithm relying on floating point
evaluation of modular functions and on interpolation, which has received little
attention in the literature, has a complexity that is essentially (up to
logarithmic factors) linear in the size of the computed polynomials. In
particular, it obtains the classical modular polynomials $\Phi_\ell$ of prime
level $\ell$ in time O (\ell^3 \log^4 \ell \log \log \ell). Besides treating
modular polynomials for $\Gamma^0 (\ell)$, which are an important ingredient in
many algorithms dealing with isogenies of elliptic curves, the algorithm is
easily adapted to more general situations. Composite levels are handled just as
easily as prime levels, as well as polynomials between a modular function and
its transform of prime level, such as the Schl\"afli polynomials and their
generalisations. Our distributed implementation of the algorithm confirms the
theoretical analysis by computing modular equations of record level around
10000 in less than two weeks on ten processors.


title: Beauty production using D* + mu and mu+ mu- correlations at ZEUS

abstract:
  Events with observed D* and/or muons in the final state were used to indicate
the presence of beauty quark production and to study the correlations between
the particles coming from the same or different B-hadrons. The Next-to-Leading
Order (NLO) theoretical predictions for such processes were often available
only at parton level. A method to calculate visible level cross sections at
NLO, based on an interface of the FMNR program to PYTHIA 6.2, is applied. It
uses the NLO description at b-quark level provided by FMNR applying a
statistical reduction procedure (REDSTAT) that allows the link to PYTHIA, from
where the description of the B-hadron decay chain is obtained. Comparisons of
the data and NLO cross sections at visible and b-quark level were found to be
consistent and equivalent.


title: Measurement-induced manipulation of the quantum-classical border

abstract:
  We demonstrate the possibility of controlling the border between the quantum
and the classical world by performing nonselective measurements on quantum
systems. We consider a quantum harmonic oscillator initially prepared in a
Schroedinger cat state and interacting with its environment. We show that the
environment induced decoherence transforming the cat state into a statistical
mixture can be strongly inhibited by means of appropriate sequences of
measurements.


title: Soft-collinear effects in prompt photon production

abstract:
  We extend next-to-leading logarithmic threshold and joint resummation for
prompt photon production to include leading collinear effects. The impact of
these effects is assessed for both fixed-target and collider kinematics. We
find them in general to be small, but noticeable.


title: Confining ensemble of dyons

abstract:
  We construct the integration measure over the moduli space of an arbitrary
number of N kinds of dyons of the pure SU(N) gauge theory at finite
temperatures. The ensemble of dyons governed by the measure is mathematically
described by a (supersymmetric) quantum field theory that is exactly solvable
and is remarkable for a number of striking features: 1) The free energy has the
minimum corresponding to the zero average Polyakov line, as expected in the
confining phase; 2)The correlation function of two Polyakov lines exhibits a
linear potential between static quarks in any N-ality non-zero representation,
with a calculable string tension roughly independent of temperature; 3) The
average spatial Wilson loop falls off exponentially with its area and the same
string tension; 4) At a critical temperature the ensemble of dyons rearranges
and de-confines; 5)The estimated ratio of the critical temperature to the
square root of the string tension is in excellent agreement with the lattice
data.


title: Python for Education: Computational Methods for Nonlinear Systems

abstract:
  We describe a novel, interdisciplinary, computational methods course that
uses Python and associated numerical and visualization libraries to enable
students to implement simulations for a number of different course modules.
Problems in complex networks, biomechanics, pattern formation, and gene
regulation are highlighted to illustrate the breadth and flexibility of
Python-powered computational environments.


title: Exact fuzzy sphere thermodynamics in matrix quantum mechanics

abstract:
  We study thermodynamical properties of a fuzzy sphere in matrix quantum
mechanics of the BFSS type including the Chern-Simons term. Various quantities
are calculated to all orders in perturbation theory exploiting the one-loop
saturation of the effective action in the large-N limit. The fuzzy sphere
becomes unstable at sufficiently strong coupling, and the critical point is
obtained explicitly as a function of the temperature. The whole phase diagram
is investigated by Monte Carlo simulation. Above the critical point, we obtain
perfect agreement with the all order results. In the region below the critical
point, which is not accessible by perturbation theory, we observe the Hagedorn
transition. In the high temperature limit our model is equivalent to a totally
reduced model, and the relationship to previously known results is clarified.


title: Kerr-Schild Photonlike Metric Solutions

abstract:
  The charged and spinning lightlike solutions are obtained in the Kerr-Schild
formalism. In particular, one of them may be considered as an ultrarelativistic
boost of the Kerr-Newman solution along the direction of angular momentum. The
Kerr singular ring disappears, however, there remains a finite parameter $a$
which determines spin by the Kerr relation $J=ma$. By $J=\hbar$, the parameter
$a$ is de Broglie wavelength of the corresponding photon. Electromagnetic field
is aligned to the Kerr null congruence. Some of the presented solutions contain
singular beam pulse (pp-strings) like the considered recently `gyratons'.


title:
Relativistic self-consistent-field calculations of the hyperfine
  structure in the 4d-shell ions

abstract:
  Relativistic self-consistent-field calculations of the radial hyperfine
integrals have been performed in the 4d-shell element ions. The comparison with
available experimental results gives an estimate of configuration interaction
effects in the hyperfine interaction in these ions. The results can also be
used to derive nuclear moments from laserspectroscopic measurements of
radioactive isotopes.
  PACS Numbers: 31.15.Ne, 31.30.Gs, 32.10.Fn


title: On the dynamical mass generation in confining Yang-Mills theories

abstract:
  The dynamical mass generation for gluons is discussed in Euclidean Yang-Mills
theories supplemented with a renormalizable mass term. The mass parameter is
not free, being determined in a self-consistent way through a gap equation
which obeys the renormalization group. The example of the Landau gauge is
worked out explicitly at one loop order. A few remarks on the issue of the
unitarity are provided.


title:
The building up of the disk galaxy M33 and the evolution of the
  metallicity gradient

abstract:
  The evolution of radial gradients of metallicity in disk galaxies and its
relation with the disk formation are not well understood. Theoretical models of
galactic chemical evolution make contrasting predictions about the time
evolution of metallicity gradients. To test chemical evolution models and trace
the star formation and accretion history of low luminosity disk galaxies we
focus on the Local Group galaxy M33. We analyze O/H and S/H abundances in
planetary nebulae, H{\sc ii} regions, and young stars, together with known
[Fe/H] abundances in the old stellar population of M33. With a theoretical
model, we follow the time evolution of gas (diffuse and condensed in clouds),
stars, and chemical abundances in the disk of M33, assuming that the galaxy is
accreting gas from an external reservoir. Our model is able to reproduce the
available observational constraints on the distribution of gas and stars in M33
and to predict the time evolution of several chemical abundances. In
particular, we find that a model characterized by a continuous infall of gas on
the disk, at a rate of $\dot M_{\rm inf}\approx 1$ $M_\odot$ yr$^{-1}$, almost
constant with time, can also account for the relatively high rate of star
formation and for the shallow chemical gradients. Supported by a large sample
of high resolution observations for this nearby galaxy, we conclude that the
metallicity in the disk of M33 has increased with time at all radii, with a
continuous flattening of the gradient over the last $\sim 8$ Gyr.


title:
The Ionization Fraction of Barnard 68: Implications for Star and Planet
  Formation

abstract:
  We present a detailed study of the ionization fraction of the Barnard 68
pre-stellar core, using millimeter H13CO+ and DCO+ lines observations. These
observations are compared to the predictions of a radiative transfer model
coupled to a chemical network that includes depletion on grains and gas phase
deuterium fractionation. Together with previous observations and modelling of
CO and isotopologues, our H13CO+ and DCO+ observations and modelling allow to
place constraints on the metal abundance and the cosmic ionization rate. The
H13CO+ emission is well reproduced for metals abundances lower than 3e-9 and a
standard cosmic ray ionization rate. However, the observations are also
consistent with a complete depletion of metals, i.e. with cosmic rays as the
only source of ionization at visual extinctions greater than a few Av . The
DCO+ emission is found to be dependent of the ortho to para H2 ratio, and
indicates a ratio of ~1e-2. The derived ionization fraction is about 5e-9 with
respect to H nuclei, which is about an order of magnitude lower than the one
observed in the L1544 core. The corresponding ambipolar diffusion timescale is
found to be an order of magnitude larger than the free fall timescale at the
center of the core. The inferred metal abundance suggests that magnetically
inactive regions (dead zones) are present in protostellar disks.


title: II. The mass gap and solution of the quark confinement problem in QCD

abstract:
  We have investigated a closed system of equations for the quark propagator,
obtained earlier within our general approach to QCD at low energies. It implies
quark confinement (the quark propagator has no pole, indeed), as well as the
dynamical breakdown of chiral symmetry (a chiral symmetry preserving solution
is forbidded). This system can be solved exactly in the chiral limit. We have
established the space of the smooth test functions (consisting of the Green's
functions for the quark propagator and the corresponding quark-gluon vertex) in
which our generalized function (the confining gluon propagator) becomes a
continuous linear functional. It is a linear topological space $K(c)$ of the
infinitely differentiable functions (with respect to the dimensionless momentum
variable $x$), having compact support in the region $x \leq c$. We develop an
analytical formalism, the so-called chiral perturbtion theory at the
fundamental quark level, which allows one to find explicit solution for the
quark propagator in powers of the light quark masses. We also develop an
analytical formalism, which allows one to find the solution for the quark
propagator in the inverse powers of the heavy quark masses. It justifies the
use for the heavy quark propagator its free counterpart up to terms of the
order $1/m_Q^3$, where $m_Q$ is the heavy quark mass. So this solution
automatically possesses the heavy quark spin-flavor symmetry.


title: MICS Asia Phase II - Sensitivity to the aerosol module

abstract:
  In the framework of the model inter-comparison study - Asia Phase II (MICS2),
where eight models are compared over East Asia, this paper studies the
influence of different parameterizations used in the aerosol module on the
aerosol concentrations of sulfate and nitrate in PM10. An intracomparison of
aerosol concentrations is done for March 2001 using different configurations of
the aerosol module of one of the model used for the intercomparison. Single
modifications of a reference setup for model configurations are performed and
compared to a reference case. These modifications concern the size
distribution, i.e. the number of sections, and physical processes, i.e.
coagulation, condensation/evaporation, cloud chemistry, heterogeneous reactions
and sea-salt emissions. Comparing monthly averaged concentrations at different
stations, the importance of each parameterization is first assessed. It is
found that sulfate concentrations are little sensitive to sea-salt emissions
and to whether condensation is computed dynamically or by assuming
thermodynamic equilibrium. Nitrate concentrations are little sensitive to cloud
chemistry. However, a very high sensitivity to heterogeneous reactions is
observed. Thereafter, the variability of the aerosol concentrations to the use
of different chemistry transport models (CTMs) and the variability to the use
of different parameterizations in the aerosol module are compared. For sulfate,
the variability to the use of different parameterizations in the aerosol module
is lower than the variability to the use of different CTMs. However, for
nitrate, for monthly averaged concentrations averaged over four stations, these
two variabilities have the same order of magnitude.


title: GRB 050410 and GRB 050412: are they really dark GRBs?

abstract:
  We present a detailed analysis of the prompt and afterglow emission of GRB
050410 and GRB 050412 detected by Swift for which no optical counterpart was
observed. The 15-150 keV energy distribution of the GRB 050410 prompt emission
shows a peak energy at 53 keV. The XRT light curve of this GRB decays as a
power law with a slope of alpha=1.06+/-0.04. The spectrum is well reproduced by
an absorbed power law with a spectral index Gamma_x=2.4+/-0.4 and a low energy
absorption N_H=4(+3;-2)x10^21 cm^(-2) which is higher than the Galactic value.
The 15-150 keV prompt emission in GRB 050412 is modelled with a hard
(Gamma=0.7+/-0.2) power law. The XRT light curve follows a broken power law
with the first slope alpha_1=0.7+/-0.4, the break time T_break=254(-41;+79) s
and the second slope alpha_2=2.8(-0.8;+0.5). The spectrum is fitted by a power
law with spectral index Gamma_x=1.3+/-0.2 which is absorbed at low energies by
the Galactic column. The GRB 050410 afterglow reveals the expected
characteristics of the third component of the canonical Swift light curve.
Conversely, a complex phenomenology was detected in the GRB 050412 because of
the presence of the very early break. The light curve in this case can be
interpreted as being the last peak of the prompt emission. The two bursts
present tight upper limits for the optical emission, however, neither of them
can be clearly classified as dark. For GRB 050410, the suppression of the
optical afterglow could be attributed to a low density interstellar medium
surrounding the burst. For GRB 050412, the evaluation of the darkness is more
difficult due to the ambiguity in the extrapolation of the X-ray afterglow
light curve.


title:
Deriving temperature, mass and age of evolved stars from high-resolution
  spectra. Application to field stars and the open cluster IC 4651

abstract:
  We test our capability of deriving stellar physical parameters of giant stars
by analysing a sample of field stars and the well studied open cluster IC 4651
with different spectroscopic methods. The use of a technique based on
line-depth ratios (LDRs) allows us to determine with high precision the
effective temperature of the stars and to compare the results with those
obtained with a classical LTE abundance analysis. (i) For the field stars we
find that the temperatures derived by means of the LDR method are in excellent
agreement with those found by the spectral synthesis. This result is extremely
encouraging because it shows that spectra can be used to firmly derive
population characteristics (e.g., mass and age) of the observed stars. (ii) For
the IC 4651 stars we use the determined effective temperature to derive the
following results. a) The reddening E(B-V) of the cluster is 0.12+/-0.02,
largely independent of the color-temperature calibration used. b) The age of
the cluster is 1.2+/-0.2 Gyr. c) The typical mass of the analysed giant stars
is 2.0+/-0.2M_sun. Moreover, we find a systematic difference of about 0.2 dex
in log g between spectroscopic and evolutionary values. We conclude that, in
spite of known limitations, a classical spectroscopic analysis of giant stars
may indeed result in very reliable stellar parameters. We caution that the
quality of the agreement, on the other hand, depends on the details of the
adopted spectroscopic analysis.


title:
A Rational Method for Probing Macromolecules Dissociation: The
  Antibody-Hapten System

abstract:
  The unbinding process of a protein-ligand complex of major biological
interest was investigated by means of a computational approach at atomistic
classical mechanical level. An energy minimisation-based technique was used to
determine the dissociation paths of the system by probing only a relevant set
of generalized coordinates. The complex problem was reduced to a
low-dimensional scanning along a selected distance between the protein and the
ligand. Orientational coordinates of the escaping fragment (the ligand) were
also assessed in order to further characterise the unbinding. Solvent effects
were accounted for by means of the Poisson--Boltzmann continuum model. The
corresponding dissociation time was derived from the calculated barrier height,
in compliance with the experimentally reported Arrhenius-like behaviour. The
computed results are in good agreement with the available experimental data.


title: L^2 harmonics forms on non compact manifolds

abstract:
  The source of these notes is a series of lectures given at the CIMPA's summer
school "Recent Topics in Geometric Analysis".


title: Particle Interpretations of the PVLAS Data

abstract:
  Recently the PVLAS collaboration reported the observation of a rotation of
linearly polarized laser light induced by a transverse magnetic field -- a
signal being unexpected within standard QED. In this review, we emphasize two
mechanisms which have been proposed to explain this result: production of a
single light neutral spin-zero particle or pair production of light minicharged
particles. We discuss a class of models, involving, in addition to our familiar
``visible'' photon, further light ``hidden paraphotons'', which mix
kinematically with the visible one, and further light paracharged particles. In
these models, very strong astrophysical and cosmological bounds on the weakly
interacting light particles mentioned above can be evaded. In the upcoming
year, a number of decisive laboratory based tests of the particle
interpretation of the PVLAS anomaly will be done. More generally, such
experiments, exploiting high fluxes of low-energy photons and/or large
electromagnetic fields, will dig into previously unconstrained parameter space
of the above mentioned models.


title: Distributed Gaussian polynomials as q-oscillator eigenfunctions

abstract:
  Karabulut and Sibert (\textit{J. Math. Phys}. \textbf{38} (9), 4815 (1997))
have constructed an orthogonal set of functions from linear combinations of
equally spaced Gaussians. In this paper we show that they are actually
eigenfunctions of a q-oscillator in coordinate representation. We also
reinterpret the coordinate representation example of q-oscillator given by
Macfarlane as the functions orthogonal with respect to an unusual inner product
definition. It is shown that the eigenfunctions in both q-oscillator examples
are infinitely degenerate.


title: Euclidean Shortest Paths in Simple Cube Curves at a Glance

abstract:
  This paper reports about the development of two provably correct approximate
algorithms which calculate the Euclidean shortest path (ESP) within a given
cube-curve with arbitrary accuracy, defined by $\epsilon >0$, and in time
complexity $\kappa(\epsilon) \cdot {\cal O}(n)$, where $\kappa(\epsilon)$ is
the length difference between the path used for initialization and the
minimum-length path, divided by $\epsilon$. A run-time diagram also illustrates
this linear-time behavior of the implemented ESP algorithm.


title:
Imaginary-time formulation of steady-state nonequilibrium: application
  to strongly correlated transport

abstract:
  We extend the imaginary-time formulation of the equilibrium quantum many-body
theory to steady-state nonequilibrium with an application to strongly
correlated transport. By introducing Matsubara voltage, we keep the finite
chemical potential shifts in the Fermi-Dirac function, in agreement with the
Keldysh formulation. The formulation is applied to strongly correlated
transport in the Kondo regime using the quantum Monte Carlo method.


title:
Generalized Stability Condition for Generalized and Doubly-Generalized
  LDPC Codes

abstract:
  In this paper, the stability condition for low-density parity-check (LDPC)
codes on the binary erasure channel (BEC) is extended to generalized LDPC
(GLDPC) codes and doublygeneralized LDPC (D-GLDPC) codes. It is proved that, in
both cases, the stability condition only involves the component codes with
minimum distance 2. The stability condition for GLDPC codes is always expressed
as an upper bound to the decoding threshold. This is not possible for D-GLDPC
codes, unless all the generalized variable nodes have minimum distance at least
3. Furthermore, a condition called derivative matching is defined in the paper.
This condition is sufficient for a GLDPC or DGLDPC code to achieve the
stability condition with equality. If this condition is satisfied, the
threshold of D-GLDPC codes (whose generalized variable nodes have all minimum
distance at least 3) and GLDPC codes can be expressed in closed form.


title:
Rigidity-dependent cosmic ray energy spectra in the knee region obtained
  with the GAMMA experiment

abstract:
  On the basis of the extensive air shower (EAS) data obtained by the GAMMA
experiment, the energy spectra and elemental composition of the primary cosmic
rays are derived in the 1-100 PeV energy range. The reconstruction of the
primary energy spectra is carried out using an EAS inverse approach in the
framework of the SIBYLL2.1 and QGSJET01 interaction models and the hypothesis
of power-law primary energy spectra with rigidity-dependent knees. The energy
spectra of primary H, He, O-like and Fe-like nuclei obtained with the SIBYLL
interaction model agree with corresponding extrapolations of the balloon and
satellite data to ~1 PeV energies. The energy spectra obtained from the QGSJET
model show a predominantly proton composition in the knee region. The
rigidity-dependent knee feature of the primary energy spectra for each
interaction model is displayed at the following rigidities: ~2.5+/-0.2 PV
(SIBYLL) and ~3.1-4.2 PV (QGSJET). All the results presented are derived taking
into account the detector response, the reconstruction uncertainties of the EAS
parameters, and fluctuations in the EAS development.


title: Assisted chaotic inflation in brane-world cosmology

abstract:
  Assisted chaotic inflation in brane cosmology is discussed. We work in the
framework of Randall-Sundrum (RS) II model, in which adopting the RS condition
the only parameter is the five-dimensional Planck mass. Using the scalar
spectral index and the amplitude of scalar perturbations we determine both the
mass of the scalar fields responsible for inflation and the fundamental Planck
mass of the higher-dimensional theory. We find that the mass of the scalars has
the typical value of the inflaton mass in chaotic inflation ($M_I \sim 10^{13}$
GeV) and that the five-dimensional Planck mass is very close to the GUT (Grand
Unified Theories) scale ($M_5 \sim (10^{16}-10^{17})$ GeV). Furthermore, no
matter how many scalar fields we use it is not possible to have chaotic
inflation with field values below the fundamental Planck mass.


title: The SCUBA-2 "All-Sky" Survey

abstract:
  The sub-millimetre wavelength regime is perhaps the most poorly explored over
large areas of the sky, despite the considerable effort that has been expended
in making deep maps over small regions. As a consequence the properties of the
sub-millimetre sky as a whole, and of rare bright objects in particular,
remains largely unknown. Here we describe a forthcoming survey (the SCUBA-2
``All-Sky'' Survey, or SASSy) designed to address this issue by making a
large-area map of approximately one-fifth of the sky visible from the JCMT
(4800 square degrees) down to a 1 sigma noise level of 30 mJy/beam. This map
forms the pilot for a much larger survey, which will potentially map the
remaining sky visible from the JCMT, with the region also visible to ALMA as a
priority. SASSy has been awarded 500 hours for the 4800 square degree pilot
phase and will commence after the commissioning of SCUBA-2, expected in early
2008.


title: The Infrared Extinction Law at Extreme Depth in a Dark Cloud Core

abstract:
  We combined sensitive near-infrared data obtained with ground-based imagers
on the ESO NTT and VLT telescopes with space mid-infrared data acquired with
the IRAC imager on the Spitzer Space Telescope to calculate the extinction law
A_\lambda/A_K as a function of \lambda between 1.25 and 7.76 micron to an
unprecedented depth in Barnard 59, a star forming, dense core located in the
Pipe Nebula. The ratios A_\lambda/A_K were calculated from the slopes of the
distributions of sources in color-color diagrams \lambda-K vs. H-K. The
distributions in the color-color diagrams are fit well with single slopes to
extinction levels of A_K ~ 7 (A_V ~ 59 mag). Consequently, there appears to be
no significant variation of the extinction law with depth through the B59 line
of sight. However, when slopes are translated into the relative extinction
coefficients A_\lambda/A_K, we find an extinction law which departs from the
simple extrapolation of the near-infrared power law extinction curve, and
agrees more closely with a dust extinction model for a cloud with a total to
selective absorption R_V=5.5 and a grain size distribution favoring larger
grains than those in the diffuse ISM. Thus, the difference we observe could be
possibly due to the effect of grain growth in denser regions. Finally, the
slopes in our diagrams are somewhat less steep than those from the study of
Indebetouw et al. (2005) for clouds with lower column densities, and this
indicates that the extinction law between 3 and 8 micron might vary slightly as
a function of environment.


title: The Magnetic Field Structure of the LMC 2 Supershell: NGC 2100

abstract:
  We present U,B,V,R,I imaging polarimetry of NGC 2100 and its surrounding
environment, which comprise a part of the LMC 2 supershell. The morphology of
the observed position angle distribution provides a tracer of the projected
magnetic field in this environment. Our polarization maps detail regions
exhibiting similarly aligned polarization position angles, as well as more
complex position angle patterns. We observe regions of coherent fields on
spatial scales of 42 x 24 pc to 104 x 83 pc, and infer projected field
strengths of $\sim14-30\mu$G. We propose that the superposition of global
outflows from the LMC 2 environment, as well as outflows created within NGC
2100, produce the unique field geometry in the region.


title: Renormalization and Effective Actions for General Relativity

abstract:
  Quantum gravity is analyzed from the viewpoint of the renormalization group.
The analysis is based on methods introduced by J. Polchinski concerning the
perturbative renormalization with flow equations. In the first part of this
work, the program of renormalization with flow equations is reviewed and then
extended to effective field theories that have a finite UV cutoff. This is done
for a scalar field theory by imposing additional renormalization conditions for
some of the nonrenormalizable couplings. It turns out that one so obtains a
statement on the predictivity of the effective theory at scales far below the
UV cutoff. In particular, nonrenormalizable theories can be treated without
problems in the proposed framework. In the second part, the standard covariant
BRS quantization program for Euclidean Einstein gravity is applied. A momentum
cutoff regularization is imposed and the resulting violation of the
Slavnov-Taylor identities is discussed. Deriving Polchinski's renormalization
group equation for Euclidean quantum gravity, the predictivity of effective
quantum gravity at scales far below the Planck scale is investigated with flow
equations. A fine-tuning procedure for restoring the violated Slavnov-Taylor
identities is proposed and it is argued that in the effective quantum gravity
context, the restoration will only be accomplished with finite accuracy.
Finally, the no-cutoff limit of Euclidean quantum gravity is analyzed from the
viewpoint of the Polchinski method. It is speculated whether a limit with
nonvanishing gravitational constant might exist where the latter would
ultimatively be determined by the cosmological constant and the masses of the
elementary particles.


title:
ECHO: an Eulerian Conservative High Order scheme for general
  relativistic magnetohydrodynamics and magnetodynamics

abstract:
  We present a new numerical code, ECHO, based on an Eulerian Conservative High
Order scheme for time dependent three-dimensional general relativistic
magnetohydrodynamics (GRMHD) and magnetodynamics (GRMD). ECHO is aimed at
providing a shock-capturing conservative method able to work at an arbitrary
level of formal accuracy (for smooth flows), where the other existing GRMHD and
GRMD schemes yield an overall second order at most. Moreover, our goal is to
present a general framework, based on the 3+1 Eulerian formalism, allowing for
different sets of equations, different algorithms, and working in a generic
space-time metric, so that ECHO may be easily coupled to any solver for
Einstein's equations. Various high order reconstruction methods are implemented
and a two-wave approximate Riemann solver is used. The induction equation is
treated by adopting the Upwind Constrained Transport (UCT) procedures,
appropriate to preserve the divergence-free condition of the magnetic field in
shock-capturing methods. The limiting case of magnetodynamics (also known as
force-free degenerate electrodynamics) is implemented by simply replacing the
fluid velocity with the electromagnetic drift velocity and by neglecting the
matter contribution to the stress tensor. ECHO is particularly accurate,
efficient, versatile, and robust. It has been tested against several
astrophysical applications, including a novel test on the propagation of large
amplitude circularly polarized Alfven waves. In particular, we show that
reconstruction based on a Monotonicity Preserving filter applied to a fixed
5-point stencil gives highly accurate results for smooth solutions, both in
flat and curved metric (up to the nominal fifth order), while at the same time
providing sharp profiles in tests involving discontinuities.


title: Gluon condensate behaviour at filling the Fermi sphere up

abstract:
  The impact of filling up the Fermi sphere with the quarks, which dynamically
generated their masses on the instanton liquid at finite temperature and
baryonic/quark number density, is investigated. It is demonstrated, in
particular, that the boundary of chiral symmetry restoration phase transition
is shifted to the larger (about 100 MeV more) value of quark chemical potential
compared to the magnitude inherent in the Nambu-Jona-Lasinio model.


title: Callan-Symanzik method for $m$-axial Lifshitz points

abstract:
  We introduce the Callan-Symanzik method in the description of anisotropic as
well as isotropic Lifshitz critical behaviors. Renormalized perturbation
theories are defined by normalization conditions with nonvanishing masses and
at zero external momenta. The orthogonal approximation is employed to obtain
the critical indices $\eta_{L2}$, $\nu_{L2}$, $\eta_{L4}$ and $\nu_{L4}$
diagramatically at least up to two-loop order in the anisotropic criticalities.
This approximation is also utilized to compute the exponents $\eta_{L4}$ and
$\nu_{L4}$ in the isotropic case. Furthermore, we compute those exponents
exactly for the isotropic behaviors at the same loop order. The results
obtained for all exponents are in perfect agreement with those previously
derived in the massless theories renormalized at nonzero external momenta.


title: Coulomb Drag in Graphene

abstract:
  We study the Coulomb drag between two single graphene sheets in intrinsic and
extrinsic graphene systems with no interlayer tunneling. The general expression
for the nonlinear susceptibility appropriate for single-layer graphene systems
is derived using the diagrammatic perturbation theory, and the corresponding
exact zero-temperature expression is obtained analytically. We find that,
despite the existence of a non-zero conductivity in an intrinsic graphene
layer, the Coulomb drag between intrinsic graphene layers vanishes at all
temperatures. In extrinsic systems, we obtain numerical results and an
approximate analytical result for the drag resistivity $\rho_{\textrm{D}}$, and
find that $\rho_{\textrm{D}}$ goes as $T^2$ at low temperature $T$, as $1/d^4$
for large bilayer separation $d$ and $1/n^3$ for high carrier density $n$. We
also discuss qualitatively the effect of plasmon-induced enhancement on the
Coulomb drag, which should occur at a temperature of the order of or higher
than the Fermi temperature.


title:
Hamiltonian theory of the half-filled Landau level with disorder:
  Application to recent NMR data

abstract:
  The Hamiltonian Theory of the fractional quantum Hall effect is an operator
description that subsumes many properties of Composite Fermions, applies to
gapped and gapless cases, and has been found to provide results in quantitative
accord with data on gaps, relaxation rates and polarizations at temperatures of
$300mK$ and above. The only free parameter is $\lambda$, which is related to
the sample thickness and appears in the Zhang-Das Sarma potential $v(q) = {2\pi
e^2\over \kappa q} e^{-ql\lambda}$ where $l$ and $\kappa $ are the magnetic
length and dielectric constant. Here we examine the recent data of Tracy and
Eisenstein on the nuclear magnetic resonance relaxation rate at filling factor
$\nu=\half$ deduced from resistivity measurements at temperatures as low as
$45mK$. We find that their results can be satisfactorily described by this
theory, if in addition to a $v(q)$ with $\lambda \simeq 2$, a constant disorder
width $\Gamma\simeq 100 mK$ is incorporated.


title: Ergodic model for the expansion of spherical nanoplasmas

abstract:
  Recently, the collisionless expansion of spherical nanoplasmas has been
analyzed with a new ergodic model, clarifying the transition from
hydrodynamic-like to Coulomb-explosion regimes, and providing accurate laws for
the relevant features of the phenomenon. A complete derivation of the model is
here presented. The important issue of the self-consistent initial conditions
is addressed by analyzing the initial charging transient due to the electron
expansion, in the approximation of immobile ions. A comparison among different
kinetic models for the expansion is presented, showing that the ergodic model
provides a simplified description, which retains the essential information on
the electron distribution, in particular, the energy spectrum. Results are
presented for a wide range of initial conditions (determined from a single
dimensionless parameter), in excellent agreement with calculations from the
exact Vlasov-Poisson theory, thus providing a complete and detailed
characterization of all the stages of the expansion.


title:
Spin-charge filtering through a spin-orbit coupled quantum dot
  controlled via an Aharonov-Bohm interferometer

abstract:
  We show that a strongly correlated quantum dot embedded in an Aharonov-Bohm
interferometer can be used to filter both charge and spin at zero voltage bias.
The magnitude with which the Aharonov-Bohm arm is coupled to the system
controls the many-body effects on the quantum dot. When the quantum dot is in
the Kondo regime the flow of charge through the system can be tuned by the
phase of the Aharonov-Bohm arm, $\phi_{AB}$. Furthermore when a spin-orbit
interaction is present on a Kondo quantum dot we can control the flow of spin
by the spin-orbit phase, $\phi_{SO}$. The existence of the Kondo peak at the
Fermi energy makes it possible to control the flow of both charge and spin in
the zero voltage bias limit.


title: Dynamic rays of bounded-type entire functions

abstract:
  We construct an entire function in the Eremenko-Lyubich class $\B$ whose
Julia set has only bounded path-components. This answers a question of Eremenko
from 1989 in the negative.
  On the other hand, we show that for many functions in $\B$, in particular
those of finite order, every escaping point can be connected to $\infty$ by a
curve of escaping points. This gives a partial positive answer to the
aforementioned question of Eremenko, and answers a question of Fatou from 1926.


title:
(2+1)-Dimensional Quantum Gravity as the Continuum Limit of Causal
  Dynamical Triangulations

abstract:
  We perform a non-perturbative sum over geometries in a (2+1)-dimensional
quantum gravity model given in terms of Causal Dynamical Triangulations.
Inspired by the concept of triangulations of product type introduced
previously, we impose an additional notion of order on the discrete, causal
geometries. This simplifies the combinatorial problem of counting geometries
just enough to enable us to calculate the transfer matrix between boundary
states labelled by the area of the spatial universe, as well as the
corresponding quantum Hamiltonian of the continuum theory. This is the first
time in dimension larger than two that a Hamiltonian has been derived from such
a model by mainly analytical means, and opens the way for a better
understanding of scaling and renormalization issues.


title:
Restrictions on sterile neutrino parameters from astrophysical
  observations

abstract:
  Adding 3 right-handed (sterile) neutrino to the Standard Model (SM) can solve
several "beyond the Standard Model" problems within one consistent framework:
explain neutrino oscillations and baryon asymmetry of the Universe and provide
a dark matter (DM) candidate. In this talk I will present current status of
astrophysical searches for the DM sterile neutrino.


title: The Hartogs extension theorem on (n-1)-complete complex spaces

abstract:
  Employing Morse theory for the global control of monodromy and the method of
analytic discs for local extension, we establish a version of the global
Hartogs extension theorem in a singular setting: for every domain D of an
(n-1)-complete normal complex space X of pure dimension n >= 2 and for every
compact set K in D such that D - K is connected, holomorphic or meromorphic
functions in D - K extend holomorphically or meromorphically to D. Normality is
an unvavoidable assumption for holomorphic extension, but we show that
meromorphic extension holds on a reduced globally irreducible (not necessarily
normal) X of pure dimension n >=2 provided that the regular part of D - K is
connected.


title:
On limit cycles appearing by polynomial perturbation of Darbouxian
  integrable systems

abstract:
  We prove an existential finiteness Varchenko-Khovanskii type result for
integrals of rational 1-forms over the level curves of Darbouxian integrals.


title:
Density of bulk trap states in organic semiconductor crystals: discrete
  levels induced by oxygen in rubrene

abstract:
  The density of trap states in the bandgap of semiconducting organic single
crystals has been measured quantitatively and with high energy resolution by
means of the experimental method of temperature-dependent
space-charge-limited-current spectroscopy (TD-SCLC). This spectroscopy has been
applied to study bulk rubrene single crystals, which are shown by this
technique to be of high chemical and structural quality. A density of deep trap
states as low as ~ 10^{15} cm^{-3} is measured in the purest crystals, and the
exponentially varying shallow trap density near the band edge could be
identified (1 decade in the density of states per ~25 meV). Furthermore, we
have induced and spectroscopically identified an oxygen related sharp hole bulk
trap state at 0.27 eV above the valence band.


title:
The structure of sunspot penumbrae IV. MHS equilibrium for penumbral
  flux tubes and the origin of dark core penumbral filaments and penumbral
  grains

abstract:
  We study the magnetohydrostatic equilibrium of magnetic flux tubes with
circular cross sections embedded in a magnetic surrounding atmosphere. We solve
the static momentum equation in 2.5D to obtain the thermodynamics that are
consistent with a prescribed velocity and magnetic fields. We show that force
balance is roughly satisfied if the flux tube's magnetic field is aligned with
its axis. Equilibrium is guaranteed if this magnetic field possesses a
transverse component. Several forms of this transverse field are investigated.
The resulting magnetic field configurations are critically reviewed in terms of
the results from spectropolarimetric observations. The thermodynamic structure
that allows the flux tube to be in mechanical equilibrium is also calculated.
We show that the inferred pressure, density and temperature stratification
reproduce intensity features similar to dark core penumbral filaments and
penumbral grains.


title: Lectures on (abelian) Chern-Simons vortices

abstract:
  Various aspects including the construction and the symmetries of Abelian
Chern-Simons vortices are reviewed. Extended version of the Lectures delivered
at NIKHEF (Amsterdam), July 2006. Typos corrected, some refernces added.


title: Multiple pattern matching: A Markov chain approach

abstract:
  RNA motifs typically consist of short, modular patterns that include base
pairs formed within and between modules. Estimating the abundance of these
patterns is of fundamental importance for assessing the statistical
significance of matches in genomewide searches, and for predicting whether a
given function has evolved many times in different species or arose from a
single common ancestor. In this manuscript, we review in an integrated and
self-contained manner some basic concepts of automata theory, generating
functions and transfer matrix methods that are relevant to pattern analysis in
biological sequences. We formalize, in a general framework, the concept of
Markov chain embedding to analyze patterns in random strings produced by a
memoryless source. This conceptualization, together with the capability of
automata to recognize complicated patterns, allows a systematic analysis of
problems related to the occurrence and frequency of patterns in random strings.
The applications we present focus on the concept of synchronization of
automata, as well as automata used to search for a finite number of keywords
(including sets of patterns generated according to base pairing rules) in a
general text.

categories: math.PR math.CO math.ST q-bio.GN q-bio.QM stat.TH


title:
Copolymer-homopolymer blends: global energy minimisation and global
  energy bounds

abstract:
  We study a variational model for a diblock-copolymer/homopolymer blend. The
energy functional is a sharp-interface limit of a generalisation of the
Ohta-Kawasaki energy. In one dimension, on the real line and on the torus, we
prove existence of minimisers of this functional and we describe in complete
detail the structure and energy of stationary points. Furthermore we
characterise the conditions under which the minimisers may be non-unique.
  In higher dimensions we construct lower and upper bounds on the energy of
minimisers, and explicitly compute the energy of spherically symmetric
configurations.


title: Coupling of transverse and longitudinal response in stiff polymers

abstract:
  The time-dependent transverse response of stiff polymers, represented as
weakly-bending wormlike chains (WLCs), is well-understood on the linear level,
where transverse degrees of freedom evolve independently from the longitudinal
ones. We show that, beyond a characteristic time scale, the nonlinear coupling
of transverse and longitudinal motion in an inextensible WLC significantly
weakens the polymer response compared to the widely used linear response
predictions. The corresponding feedback mechanism is rationalized by scaling
arguments and quantified by a multiple scale approach that exploits an inherent
separation of transverse and longitudinal correlation length scales. Crossover
scaling laws and exact analytical and numerical solutions for characteristic
response quantities are derived for different experimentally relevant setups.
Our findings are applicable to cytoskeletal filaments as well as DNA under
tension.


title:
Supergiant Fast X-ray Transients: A common behaviour or a class of
  objects?

abstract:
  INTEGRAL monitoring of the Galactic Plane is revealing a growing number of
recurrent X-ray transients, characterised by short outbursts with very fast
rise times (~ tens of minutes) and typical durations of a few hours. A
substantial fraction of these sources are associated with OB supergiants and
hence define a new class of massive X-ray binaries, which we call Supergiant
Fast X-ray Transients. Characterisation of the astrophysical parameters of
their counterparts is underway. So far, we have found a number of late O and
early B supergiants of different luminosities at a large range of distances.
Nothing in their optical properties sets them apart from classical Supergiant
X-ray Binaries. On the other hand, there is now rather concluding evidence that
persistent supergiant X-ray binaries also show fast outbursts. This suggests a
continuum of behaviours between typical persistent supergiant systems and
purely transient systems, but offers very little information about the physical
causes of the outbursts.


title: Linear algebra and differential geometry on abstract Hilbert space

abstract:
  Isomorphisms of separable Hilbert spaces are analogous to isomorphisms of
n-dimensional vector spaces. However, while n-dimensional spaces in
applications are always realized as the Euclidean space R^n, Hilbert spaces
admit various useful realizations as spaces of functions. In the paper this
simple observation is used to construct a fruitful formalism of local
coordinates on Hilbert manifolds. Images of charts on manifolds in the
formalism are allowed to belong to arbitrary Hilbert spaces of functions
including spaces of generalized functions. Tensor equations then describe
families of functional equations on various spaces of functions. The formalism
itself and its applications in linear algebra, differential equations and
differential geometry are analyzed.


title: Delay estimation in a two-node acyclic network

abstract:
  Linear measures such as cross-correlation have been used successfully to
determine time delays from the given processes. Such an analysis often precedes
identifying possible causal relationships between the observed processes. The
present study investigates the impact of a positively correlated driver whose
correlation function decreases monotonically with lag on the delay estimation
in a two-node acyclic network with one and two-delays. It is shown that
cross-correlation analysis of the given processes can result in spurious
identification of multiple delays between the driver and the dependent
processes. Subsequently, delay estimation of increment process as opposed to
the original process under certain implicit constraints is explored.
Short-range and long-range correlated driver processes along with those of
their coarse-grained counterparts are considered.


title: Smectic elastomer membranes

abstract:
  We present a model for smectic elastomer membranes which includes elastic and
liquid crystalline degrees of freedom. Based on our model, we determined the
qualitative phase diagram of a smectic elastomer membrane using mean-field
theory. This phase diagram is found to comprise five phases, viz.
smectic-A--flat, smectic-A--crumpled, smectic-C--flat, smectic-C--crumpled and
smectic-C--tubule, where in the latter phase, the membrane is flat in the
direction of mesogenic tilt and crumpled in the perpendicular direction. The
transitions between adjacent phases are second order phase transitions. We
study in some detail the elasticity of the smectic-C--flat and the
smectic-C--tubule phases which are associated with a spontaneous breaking of
in-plane rotational symmetry. As a consequence of the Goldstone theorem, these
phases exhibit soft elasticity characterized by the vanishing of in-plane shear
moduli.