title:
Correcting for selection bias via cross-validation in the classification
  of microarray data

abstract:
  There is increasing interest in the use of diagnostic rules based on
microarray data. These rules are formed by considering the expression levels of
thousands of genes in tissue samples taken on patients of known classification
with respect to a number of classes, representing, say, disease status or
treatment strategy. As the final versions of these rules are usually based on a
small subset of the available genes, there is a selection bias that has to be
corrected for in the estimation of the associated error rates. We consider the
problem using cross-validation. In particular, we present explicit formulae
that are useful in explaining the layers of validation that have to be
performed in order to avoid improperly cross-validated estimates.


title: A Measurement of Neutralino Mass at the LHC in Light Gravitino Scenarios

abstract:
  We consider supersymmetric (SUSY) models in which a very light gravitino is
the lightest SUSY particle. Assuming that a neutralino is the next-to-lightest
SUSY particle, we present a measurement of the neutralino mass at the LHC in
two photons + missing energy events, which is based on the MT2 method. It is a
direct measurement of the neutralino mass itself, independent of other SUSY
particle masses and patterns of cascade decays before the neutralino is
produced.


title:
Fundamentals and recent developments in non-perturbative canonical
  Quantum Gravity

abstract:
  The aim of this review is to provide a detailed account of the physical
content emerging from this story of the canonical approach to Quantum Gravity.
All the crucial steps in our presentation have a pedagogical character,
providing the reader with the necessary tools to become involved in the field.
Such a pedagogical aspect is then balanced and completed by subtle discussions
on specific topics which we regard as relevant for the physical insight they
outline on the treated questions. Our analysis is not aimed at convincing the
reader about a pre-constituted point of view, bu instead our principal goal is
to review the picture of Canonical Quantum Gravity on the basis of the concrete
facts at the ground of its clear successes, but also of its striking
shortcomings.


title: Some regular symmetric pairs

abstract:
  In [AG2] we explored the question what symmetric pairs are Gelfand pairs. We
introduced the notion of regular symmetric pair and conjectured that all
symmetric pairs are regular. This conjecture would imply that many symmetric
pairs are Gelfand pairs, and in particular that any connected symmetric pair
over C is a Gelfand pair.
  In this paper we show that the pairs $$(GL(V),O(V)), (GL(V),U(V)),
(U(V),O(V)), (O(V \oplus W),O(V) \times O(W)), (U(V \oplus W),U(V) \times
U(W))$$ are regular where V and W are quadratic or hermitian spaces over
arbitrary local field of characteristic zero. We deduce from that that the
pairs $(GL_n(\C),O_n(\C))$ and $(O_{n+m}(\C),O_n(\C) \times O_m(\C))$ are
Gelfand pairs.


title:
Ambiguity of converting phase-averaged flux into luminosity for
  millisecond pulsars in gamma rays

abstract:
  We study a magnitude of possible over/underestimation of the actual gamma-ray
luminosity L_{actual} of a millisecond pulsar when using so-called pseudo
luminosity L_{pseudo} which is inferred from a phase-averaged flux. Both,
L_{actual} and L_{pseudo} are calculated with the numerical code thatmodels the
millisecond pulsar magnetospheric activity in the space charge limited flow
approximation with unscreened accelerating electric field. The behaviour of
L_{pseudo}/L_{actual} depending on viewing angle is analysed in the energy
bands corresponding to the operational energy bands of Fermi GST and H.E.S.S.
II.


title: $\ell_1 \to \ell_2 \gamma$ in type III seesaw

abstract:
  We study the decay rates of the $\mu \to e \gamma$ and $\tau \to \ell \gamma$
transitions in the framework of the type III seesaw model, where fermionic
triplets are exchanged to generate neutrino masses. We show that the
observation of one of those decays in planned experiments would contradict
bounds arising from present experimental limits on the $\mu \to eee$ and $\tau
\to 3 l$ decay rates, and therefore imply that there exist other sources of
lepton flavour violation than those associated to triplet of fermions.


title:
Non-Abelian adiabatic statistics and Hall viscosity in quantum Hall
  states and p_x+ip_y paired superfluids

abstract:
  Many trial wavefunctions for fractional quantum Hall states in a single
Landau level are given by functions called conformal blocks, taken from some
conformal field theory. Also, wavefunctions for certain paired states of
fermions in two dimensions, such as p_x+ip_y states, reduce to such a form at
long distances. Here we investigate the adiabatic transport of such
many-particle trial wavefunctions using methods from two-dimensional field
theory. One context for this is to calculate the statistics of widely-separated
quasiholes, which has been predicted to be non-Abelian in a variety of cases.
The Berry phase or matrix (holonomy) resulting from adiabatic transport around
a closed loop in parameter space is the same as the effect of analytic
continuation around the same loop with the particle coordinates held fixed
(monodromy), provided the trial functions are orthonormal and holomorphic in
the parameters so that the Berry vector potential (or connection) vanishes. We
show that this is the case (up to a simple area term) for paired states
(including the Moore-Read quantum Hall state), and present general conditions
for it to hold for other trial states (such as the Read-Rezayi series). We
argue that trial states based on a non-unitary conformal field theory do not
describe a gapped topological phase, at least in many cases. By considering
adiabatic variation of the aspect ratio of the torus, we calculate the Hall
viscosity, a non-dissipative viscosity coefficient analogous to Hall
conductivity, for paired states, Laughlin states, and more general quantum Hall
states. Hall viscosity is an invariant within a topological phase, and is
generally proportional to the "conformal spin density" in the ground state.


title: Parity-induced Selmer Growth For Symplectic, Ordinary Families

abstract:
  Let $p$ be an odd prime, and let $K/K_0$ be a quadratic extension of number
fields. Denote by $K_\pm$ the maximal $\mathbb{Z}_p$-power extensions of $K$
that are Galois over $K_0$, with $K_+$ abelian over $K_0$ and $K_-$ dihedral
over $K_0$. In this paper we show that for a Galois representation over $K_0$
satisfying certain hypotheses, if it has odd Selmer rank over $K$ then for one
of $K_\pm$ its Selmer rank over $L$ is bounded below by $[L:K]$ for $L$ ranging
over the finite subextensions of $K$ in $K_\pm$. Our method or proof
generalizes a method of Mazur--Rubin, building upon results of Nekov\'a\v{r},
and applies to abelian varieties of arbitrary dimension, (self-dual twists of)
modular forms of even weight, and (twisted) Hida families.


title:
Inequivalent quantization of the rational Calogero model with a Coulomb
  type interaction

abstract:
  We consider the inequivalent quantizations of a $N$-body rational Calogero
model with a Coulomb type interaction. It is shown that for certain range of
the coupling constants, this system admits a one-parameter family of
self-adjoint extensions. We analyze both the bound and scattering state sectors
and find novel solutions of this model. We also find the ladder operators for
this system, with which the previously known solutions can be constructed.


title: Bimodule herds

abstract:
  The notion of a bimodule herd is introduced and studied. A bimodule herd
consists of a $B$-$A$ bimodule, its formal dual, called a pen, and a map,
called a shepherd, which satisfies untiality and coassociativity conditions. It
is shown that every bimodule herd gives rise to a pair of corings and
coactions. If, in addition, a bimodule herd is tame i.e. it is faithfully flat
and a progenerator, then these corings are associated to entwining structures;
the bimodule herd is a Galois comodule of these corings. The notion of a
bicomodule coherd is introduced as a formal dualisation of the definition of a
bimodule herd. Every bicomodule coherd defines a pair of (non-unital) rings. It
is shown that a tame $B$-$A$ bimodule herd defines a bicomodule coherd, and
sufficient conditions for the derived rings to be isomorphic to $A$ and $B$ are
discussed. The composition of bimodule herds via the tensor product is
outlined. The notion of a bimodule herd is illustrated by the example of Galois
co-objects of a commutative, faithfully flat Hopf algebra.


title: Complex-Orbital Order in Fe_3O_4 and Mechanism of the Verwey Transition

abstract:
  Electronic state and the Verwey transition in magnetite (Fe_3O_4) are studied
using a spinless three-band Hubbard model for 3d electrons on the B sites with
the Hartree-Fock approximation and the exact diagonalisation method.
Complex-orbital, e.g., 1/sqrt(2)[|zx> + i |yz>], ordered (COO) states having
noncollinear orbital moments ~ 0.4 mu_B on the B sites are obtained with the
cubic lattice structure of the high-temperature phase. The COO state is a novel
form of magnetic ordering within the orbital degree of freedom. It arises from
the formation of Hund's second rule states of spinless pseudo-d molecular
orbitals in the Fe_4 tetrahedral units of the B sites and ferromagnetic
alignment of their fictitious orbital moments. A COO state with longer
periodicity is obtained with pseudo-orthorhombic Pmca and Pmc2_1 structures for
the low-temperature phase. The state spontaneously lowers the crystal symmetry
to the monoclinic and explains experimentally observed rhombohedral cell
deformation and Jahn-Teller like distortion. From these findings, we consider
that at the Verwey transition temperature, the COO state remaining to be
short-range order impeded by dynamical lattice distortion in high temperature
is developed into that with long-range order coupled with the monoclinic
lattice distortion.


title: Interface Tension of Bose-Einstein Condensates

abstract:
  Motivated by recent observations of phase-segregated binary Bose-Einstein
condensates, we propose a method to calculate the excess energy due to the
interface tension of a trapped configuration. By this method one should be able
to numerically reproduce the experimental data by means of a simple
Thomas-Fermi approximation, combined with interface excess terms and the
Laplace equation. Using the Gross-Pitaevskii theory, we find expressions for
the interface excesses which are accurate in a very broad range of the
interspecies and intraspecies interaction parameters. We also present
finite-temperature corrections to the interface tension which, aside from the
regime of weak segregation, turn out to be small.


title:
Equation of state of superfluid neutron matter and the calculation of
  $^1S_0$ pairing gap

abstract:
  We present a Quantum Monte Carlo study of the zero temperature equation of
state of neutron matter and the computation of the $^1S_0$ pairing gap in the
low-density regime with $\rho<0.04$ fm$^{-3}$. The system is described by a
non-relativistic nuclear Hamiltonian including both two-- and three--nucleon
interactions of the Argonne and Urbana type. This model interaction provides
very accurate results in the calculation of the binding energy of light nuclei.
A suppression of the gap with respect to the pure BCS theory is found, but
sensibly weaker than in other works that attempt to include polarization
effects in an approximate way.


title: Neutrino production in nucleonic interactions in gamma-ray bursters

abstract:
  Neutrinos produced in gamma-ray bursters (GRBers) may provide a unique probe
for the physics of these extreme astrophysical systems. Here we discuss
neutrino production in inelastic neutron-proton collisions within the
relativistic outflows associated with GRBers. We consider both the widely used
fireball model and a recently proposed magneto-hydrodynamic (MHD) model for the
GRB outflow.


title:
The Solar Neighborhood. XX. Discovery and Characterization of 21 New
  Nearby White Dwarf Systems

abstract:
  We present medium resolution spectroscopy and multi-epoch VRI photometry for
21 new nearby (< 50 pc) white dwarf systems brighter than V ~ 17. Of the new
systems, ten are DA (including a wide double degenerate system with two DA
components), eight are DC, two are DZ, and one is DB. In addition, we include
multi-epoch VRI photometry for eleven known white dwarf systems that do not
have trigonometric parallax determinations. Using model atmospheres relevant
for various types of white dwarfs (depending on spectral signatures), we
perform spectral energy distribution modeling by combining the optical
photometry with the near-infrared JHK from the Two Micron All-Sky Survey to
derive physical parameters (i.e., effective temperature and distance
estimates). We find that twelve new and six known white dwarf systems are
estimated to be within the NStars and Catalog of Nearby Stars horizons of 25
pc. Coupled with identical analyses of the 56 white dwarf systems presented in
Paper XIX of this series, a total of 20 new white dwarf systems and 18 known
white dwarf systems are estimated to be within 25 pc. These 38 systems of the
88 total studied represent a potential 34% increase in the 25 pc white dwarf
population (currently known to consist of 110 systems with trigonometric
parallaxes of varying qualities). We continue an ongoing effort via CTIOPI to
measure trigonometric parallaxes for the systems estimated to be within 25 pc
to confirm proximity and further fill the incompleteness gap in the local white
dwarf population. Another 38 systems (both new and known) are estimated to be
between 25 and 50 pc and are viable candidates for ground-based parallax
efforts wishing to broaden the horizon of interest.


title: An asymptotically normal test for the selective neutrality hypothesis

abstract:
  An important parameter in the study of population evolution is
$\theta=4N\nu$, where $N$ is the effective population size and $\nu$ is the
rate of mutation per locus per generation. Therefore, $\theta$ represents the
mean number of mutations per site per generation. There are many estimators of
$\theta$, one of them being the mean number of pairwise nucleotide differences,
which we call $\mathcal{T}_2$. Other estimators are $\mathcal{T}_1$, based on
the number of segregating sites and $\mathcal{T}_3$, based on the number of
singletons. The concept of selective neutrality can be interpreted as a
differentiated nucleotide distribution for mutant sites when compared to the
overall nucleotide distribution. Tajima (1989) has proposed the so-called
Tajima's test of selective neutrality based on $\mathcal{T}_2-\mathcal{T}_1$.
Its complex empirical behavior (Kiihl, 2005) motivates us to propose a test
statistic solely based on $\mathcal{T}_2$. We are thus able to prove asymptotic
normality under different assumptions on the number of sequences and number of
sites via $U$-statistics theory.


title: Observables sensitive to absolute neutrino masses. II

abstract:
  In this followup to Phys. Rev. D 75, 053001 (2007) [arXiv:hep-ph/0608060] we
report updated constraints on neutrino mass-mixing parameters, in light of
recent neutrino oscillation data (KamLAND, SNO, and MINOS) and cosmological
observations (WMAP 5-year and other data). We discuss their interplay with the
final 0nu2beta decay results in 76-Ge claimed by part of the Heidelberg-Moscow
Collaboration, using recent evaluations of the corresponding nuclear matrix
elements, and their uncertainties. We also comment on the 0nu2beta limits in
130-Te recently set by Cuoricino, and on prospective limits or signals from the
KATRIN experiment.


title: N/V-limit for Langevin dynamics in continuum

abstract:
  We construct an infinite particle/infinite volume Langevin dynamics on the
space of configurations in $\R^d$ having velocities as marks. The construction
is done via a limiting procedure using $N$-particle dynamics in cubes
$(-\lambda,\lambda]^d$ with periodic boundary conditions. A main step to this
result is to derive an (improved) Ruelle bound for the canonical correlation
functions of $N$-particle systems in $(-\lambda,\lambda]^d$ with periodic
boundary conditions. After proving tightness of the laws of finite particle
dynamics, the identification of accumulation points as martingale solutions of
the Langevin equation is based on a general study of properties of measures on
configuration space (and their weak limit) fulfilling a uniform Ruelle bound.
Additionally, we prove that the initial/invariant distribution of the
constructed dynamics is a tempered grand canonical Gibbs measure. All proofs
work for general repulsive interaction potentials $\phi$ of Ruelle type (e.g.
the Lennard-Jones potential) and all temperatures, densities and dimensions
$d\geq 1$.


title: Emergence of Secondary Motifs in Tube-Like Polymers in a Solvent

abstract:
  We study the effects of two kinds of interactions in tube-like polymers and
demonstrate that they result in the formation of secondary motifs. The first
has an entropic origin and is a measure of the effective space available to the
solvent. The second arises from solvophobic interactions of the solvent with
the polymers and leads to an energy proportional to the contact surface between
the tube and solvent particles. The solvent molecules are modeled as hard
spheres and the two interactions are considered separately with the solvent
density affecting their relative strength. In addition to analytical
calculations, we present the results of numerical simulations in order to
understand the role played by the finite length of short polymers and the
discrete versus continuum descriptions of the system in determining the
preferred conformation.


title:
Complex structures on tangent and cotangent Lie algebras of dimension
  six

abstract:
  This paper deals with complex structures on Lie algebras $\ct_{\pi} \hh=\hh
\ltimes_{\pi} V$, where $\pi$ is either the adjoint or the coadjoint
representation. The main topic is the existence question of complex structures
on $\ct_{\pi} \hh$ for $\hh$ a three dimensional real Lie algebra. First it was
proposed the study of complex structures $J$ satisfying the constrain $J\hh=V$.
Whenever $\pi$ is the adjoint representation this kind of complex structures
are associated to non singular derivations of $\hh$. This fact derives
different kind of applications. Finally an approach to the pseudo K\"ahler
geometry was done.


title: Recent results from KLOE experiment

abstract:
  We report the newest results from the KLOE experiment on hadronic physics,
such as the parameters of scalars f0 and a0, the eta meson mass measurements
and dynamics, the first observation of the eta -> p+p-e+e- rare decay, and
study of e+e- -> omega p0 cross section around the phi resonance.


title:
Epigenetic Tracking, a Method to Generate Arbitrary Shapes By Using
  Evolutionary-Developmental Techniques

abstract:
  This paper describes an Artificial Embryology method (called ``Epigenetic
Tracking'') to generate predefined arbitrarily shaped 2-dimensional arrays of
cells by means of evolutionary techniques. It is based on a model of
development, whose key features are: i) the distinction bewteen ``normal'' and
``driver'' cells, being the latter able to receive guidance from the genome,
ii) the implementation of the proliferation/apoptosis events in such a way that
many cells are created/deleted at once, in order to speed-up the morphogenetic
process. iii) the presence in driver cells of an epigenetic memory, that holds
the position of the cell in the cell lineage tree and represents the source of
differentiation during development. The experiments performed with a number of
100x100 black and white and colour target shapes (the horse, the couple, the
hand, the dolphin, the map of Britain, the foot, the frog, the baby, the
stomach, the french flag, the head) bring to the conclusion that the method
described is able to generate any target shape, outperforming any other known
method in terms of size and variety of the generated shapes. The interpretation
of the proposed method as a model of embryogenesis and its biological
implications are discussed.


title: Model selection and sensitivity analysis for sequence pattern models

abstract:
  In this article we propose a maximal a posteriori (MAP) criterion for model
selection in the motif discovery problem and investigate conditions under which
the MAP asymptotically gives a correct prediction of model size. We also
investigate robustness of the MAP to prior specification and provide guidelines
for choosing prior hyper-parameters for motif models based on sensitivity
considerations.


title: Searches for GMSB at the LHC

abstract:
  In SUSY models with Gauge Mediated Supersymmetry Breaking (GMSB) a gravitino
is the lightest SUSY particle (LSP), while a neutralino or a slepton is the
next-to-lightest (NLSP). For the pair-production of SUSY particles at the LHC
large missing transverse energy (from the gravitinos) and two photons or
leptons in the final state are expected, if the NLSP decays inside the
detector. In the case of stable NLSPs, interesting signatures consist of
non-pointing photons or heavy stable charged particles. In this presentation
methods developed by the ATLAS and CMS collaborations and the expected
performance derived from simulations are summarized.


title:
CP Asymmetries in bar B -> bar K* (-> bar K pi) l+ l- and Untagged bar
  B_s,B_s -> phi (-> K+ K-) l+ l- Decays at NLO

abstract:
  The decay bar B -> bar K* (-> bar K pi) l+ l- offers great opportunities to
explore the physics at and above the electroweak scale by means of an angular
analysis. We investigate the physics potential of the seven CP asymmetries plus
the asymmetry in the rate, working at low dilepton mass using QCD factorization
at next-to leading order (NLO). The b ->s CP asymmetries are doubly
Cabibbo-suppressed \lesssim 1 % in the Standard Model and its extensions where
the CKM matrix is the only source of CP violation. Three CP asymmetries are
T-odd, and can be O(1) in the presence of non-standard CP violation. The T-even
asymmetries can reach O(0.1), limited by the small strong phases in the large
recoil region. We furthermore point out an easy way to measure CP phases from
time-integrated, untagged bar B_d, B_d -> K* (-> K0 pi0) l+ l- and bar B_s,B_s
-> phi (-> K+ K-) l+ l- decays. Analyses of these CP asymmetries can rule out,
or further support the minimal description of CP violation through the CKM
mechanism. Experimental studies are promising for (super) flavor factories and
at hadron colliders.


title: YORP torque as the function of shape harmonics

abstract:
  The second order analytical approximation of the mean YORP torque components
is given as an explicit function of the shape spherical harmonics coefficients
for a sufficiently regular minor body. The results are based upon a new
expression for the insolation function, significantly simpler than in previous
works. Linearized plane parallel model of the temperature distribution derived
from the insolation function allows to take into account a nonzero
conductivity. Final expressions for the three average components of the YORP
torque related with rotation period, obliquity, and precession are given in a
form of Legendre series of the cosine of obliquity. The series have good
numerical properties and can be easily truncated according to the degree of
Legendre polynomials or associated functions, with first two terms playing the
principal role. The present version fixes the errors discovered in the text
that appeared in Monthly Notices RAS (388, pp. 297-944).


title:
Bound states in inhomogeneous magnetic field in graphene: a
  semiclassical approach

abstract:
  We derive semiclassical quantization equations for graphene mono- and bilayer
systems where the excitations are confined by the applied inhomogeneous
magnetic field. The importance of a semiclassical phase, a consequence of the
spinor nature of the excitations, is pointed out. The semiclassical
eigenenergies show good agreement with the results of quantum mechanical
calculations based on the Dirac equation of graphene and with numerical tight
binding calculations.


title: Parametric Normal-Mode Splitting in Cavity Optomechanics

abstract:
  Recent experimental progress in cavity optomechanics has allowed cooling of
mesoscopic mechanical oscillators via dynamic backaction provided by the
parametric coupling to either an optical or an electrical resonator. Here we
analyze the occurrence of normal-mode splitting in backaction cooling at high
input power. We find that a hybridization of the oscillator's motion with the
fluctuations of the driving field occurs and leads to a splitting of the
mechanical and optical fluctuation spectra. Moreover, we find that cooling
experiences a classical limitation through the cavity lifetime.


title:
Maximal Solutions of Semilinear Elliptic Equations with Locally
  Integrable Forcing Term

abstract:
  We study the existence of a maximal solution of $-\Gd u+g(u)=f(x)$ in a
domain $\Gw\subset \BBR^N$ with compact boundary, assuming that $f\in
(L^1_{loc}(\Gw))_+$ and that $g$ is nondecreasing, $g(0)\geq 0$ and $g$
satisfies the Keller-Osserman condition. We show that if the boundary satisfies
the classical $C_{1,2}$ Wiener criterion then the maximal solution is a large
solution, i.e., it blows up everywhere on the boundary. In addition we discuss
the question of uniqueness of large solutions.


title: Neutrinos self interactions in Supernovae

abstract:
  Oscillations of neutrino emerging from a supernova core are studied. In this
extremely high density region neutrino self interactions induce collective
flavor transitions. When collective transitions are decoupled from matter
oscillations, as for our chosen matter profile, an analytical interpretation of
the collective effects is possible, by means of a mechanical analogy with a
spherical pendulum. For inverted neutrino hierarchy the neutrino propagation
can be divided in three regimes: synchronization, bipolar oscillations, and
spectral split. Our simulation shows that averaging over neutrino trajectories
does not alter the nature of these three regimes.


title: The Laplacian on homogeneous spaces

abstract:
  The solution of the eigenvalue problem of the Laplacian on a general
homogeneous space G/H is given. Here, G is a compact, semisimple Lie group, H
is a closed subgroup of G, and the rank of H is equal to the rank of G. It is
shown that the multiplicity of the lowest eigenvalue of the Laplacian on G/H is
just the degeneracy of the lowest Landau level for a particle moving on G/H in
the presence of the background gauge field. Moreover, the eigenspace of the
lowest eigenvalue of the Laplacian on G/H is, up to a sign, equal to the
G-equivariant index of the Dirac operator of Kostant on G/H.

categories: math-ph cond-mat.mes-hall hep-th math.MP math.RT


title: Finding how many isolating integrals of motion an orbit obeys

abstract:
  The correlation dimension, that is, the dimension obtained by computing the
correlation function of pairs of points of a trajectory in phase space, is a
numerical technique introduced in the field of nonlinear dynamics in order to
compute the dimension of the manifold in which an orbit moves, without the need
of knowing the actual equations of motion that give rise to the trajectory.
This technique has been proposed in the past as a method to measure the
dimension of stellar orbits in astronomical potentials, i.e., the number of
isolating integrals of motion the orbits obey. Although the algorithm can in
principle yield that number, some care has to be taken in order to obtain good
results. We studied the relevant parameters of the technique, found their
optimal values, and tested the validity of the method on a number of potentials
previously studied in the literature, using the SALI, Lyapunov exponents and
spectral dynamics as gauges.


title:
Asymptotic behaviour for the gradient of large solutions to some
  nonlinear elliptic equations

abstract:
  If $h$ is a nondecreasing real valued function and $0\leq q\leq 2$, we
analyse the boundary behaviour of the gradient of any solution $u$ of $-\Delta
u+h(u)+\abs {\nabla u}^q=f$ in a smooth N-dimensional domain $\Omega$ with the
condition that $u$ tends to infinity when $x$ tends to $\partial\Omega$. We
give precise expressions of the blow-up which, in particular, point out the
fact that the phenomenon occurs essentially in the normal direction to
$\partial\Omega$. Motivated by the blow--up argument in our proof, we also give
in Appendix a symmetry result for some related problems in the half space.


title: The rationality of certain moduli spaces of curves of genus 3

abstract:
  We show, for each algebraically closed field, the rationality of the
following two moduli spaces: M(3,3) parametrizing pairs (C, \eta) where C has
genus 3 and \eta is a 3-torsion divisor class, respectively of M(3,<3>)
parametrizing pairs (C, <\eta>) as above and where <\eta> is the cyclic
subgroup of order 3 in Pic_0(C) generated by \eta.


title: Symmetry of large solutions of nonlinear elliptic equations in a ball

abstract:
  Let $g$ be a locally Lipschitz continuous real valued function which
satisfies the Keller-Osserman condition and is convex at infinity, then any
large solution of $-\Delta u+g(u)=0$ in a ball is radially symmetric.


title: The entropic boundary law in BF theory

abstract:
  We compute the entropy of a closed bounded region of space for pure 3d
Riemannian gravity formulated as a topological BF theory for the gauge group
SU(2) and show its holographic behavior. More precisely, we consider a fixed
graph embedded in space and study the flat connection spin network state
without and with particle-like topological defects. We regularize and compute
exactly the entanglement for a bipartite splitting of the graph and show it
scales at leading order with the number of vertices on the boundary (or
equivalently with the number of loops crossing the boundary). More generally
these results apply to BF theory with any compact gauge group in any space-time
dimension.


title: A toolkit for a generative lexicon

abstract:
  In this paper we describe the conception of a software toolkit designed for
the construction, maintenance and collaborative use of a Generative Lexicon. In
order to ease its portability and spreading use, this tool was built with free
and open source products. We eventually tested the toolkit and showed it
filters the adequate form of anaphoric reference to the modifier in endocentric
compounds.


title: Color Grosse-Wulkenhaar models: One-loop $\beta$-functions

abstract:
  The $\beta$-functions of O(N) and U(N) invariant Grosse-Wulkenhaar models are
computed at one loop using the matrix basis. In particular, for ``parallel
interactions", the model is proved asymptotically free in the UV limit for $N
>1$, and has a triviality problem or Landau ghost for $N<1$. The vanishing
$\beta$-function is recovered solely at N=1. We discuss various possible
consequences of these results.


title:
A method for the quantitative study of atomic transitions in a magnetic
  field based on an atomic vapor cell with L=lambda

abstract:
  We describe the so-called "Lambda-Zeeman method" to investigate individual
hyperfine transitions between Zeeman sublevels of atoms in an external magnetic
field of 0.1 mT - 0.25 T. Atoms are confined in a nanocell with thickness L =
Lambda, where Lambda is the resonant wavelength (794 nm or 780 nm for D1 or D2
line of Rb). Narrow resonances in the transmission spectrum of the nanocell are
split into several components in a magnetic field; their frequency positions
and probabilities depend on the B-field. Possible applications are described,
such as magnetometers with nanometric spatial resolution and tunable atomic
frequency references.


title:
Helium Nova on a Very Massive White Dwarf -- A Light Curve Model of V445
  Puppis (2000) Revised

abstract:
  V445 Pup (2000) is a unique object identified as a helium nova. Color indexes
during the outburst are consistent with those of free-free emission. We present
a free-free emission dominated light curve model of V445 Pup on the basis of
the optically thick wind theory. Our light curve fitting shows that (1) the
white dwarf (WD) mass is very massive (M_WD \gtrsim 1.35 M_\sun), and (2) a
half of the accreted matter remains on the WD, both of which suggest that the
increasing WD mass. Therefore, V445 Pup is a strong candidate of Type Ia
supernova progenitor. The estimated distance to V445 Pup is now consistent with
the recent observational suggestions, 3.5 < d < 6.5 kpc. A helium star
companion is consistent with the brightness of m_v=14.5 mag just before the
outburst, if it is a little bit evolved hot (\log T (K) \gtrsim 4.5) star with
the mass of M_He \gtrsim 0.8 M_\sun. We then emphasize importance of
observations in the near future quiescent phase after the thick circumstellar
dust dissipates away, especially its color and magnitude to specify the nature
of the companion star. We have also calculated helium ignition masses for
helium shell flashes against various helium accretion rates and discussed the
recurrence period of helium novae.


title:
Dynamics of Electrons in Gradient Nanostructures (Exactly Solvable
  Model)

abstract:
  A flexible multi-parameter exactly solvable model of potential profile,
containing an arbitrary number of continuous smoothly shaped barriers and
wells, both equal or unequal, characterized by finite values and continuous
profiles of the potential and of its gradient, is presented. We demonstrate an
influence of both gradient and curvature of these potentials on the electron
transport and spectra of symmetric and asymmetric double-well (DW) potentials.
The use of this model is simplified due to one to one correspondence between
the algorithms of calculation of the transmittance of convex barriers and
energy spectra of concave wells. We have shown that the resonant contrast
between maximum and minimum in over-barrier reflectivity of curvilinear barrier
exceeds significantly the analogous effect for rectangular barrier with the
same height and width. Reflectionless tunneling of electrons below the bottom
of gradient nanostructures forming concave potential barriers is considered.
The analogy between dynamics of electrons in gradient fields and gradient
optics of heterogeneous photonic barriers is illustrated.


title:
Mapping the interface between the Local and Loop I bubbles using
  Stromgren photometry

abstract:
  The Sun is located inside an extremely low density region of quite irregular
shape called the Local Bubble. Close to the Local Bubble, there is an even
larger cavity known as Loop I. A ring-like feature observed in X-ray and HI has
been proposed as the contour of the bubbles interaction zone around 70 pc. Our
goal is to identify the interface between the Local and Loop I Bubbles and
discuss the ring's existence using Stromgren uvbyH\beta data. We have used the
uvbyH\beta data of the General Catalogue of Photometric Data, covering the
region defined by the Galactic coordinates: 250\degr <= l <= 50\degr and
-60\degr <= b <= 60\degr to obtain E(b-y) colour excess and distances. The
final sample is composed of 4346 stars located up to 500 pc from the Sun.
  The expected transition to E(b-y) ~ 0.070 - 0.100 mag, corresponding to the
ring's column density, occurs on the western part of the ring at d = 110 +/- 20
pc, whereas on the eastern side it is not clearly seen before d = 280 +/- 50
pc. Near the Galactic plane the presence of the dark clouds is clearly
established by E(b-y) >= 0.100 mag on the western side at about 100 - 150 pc
and about 120 - 180 pc on the eastern side. In the southernmost part of the
ring the reddening remains very low, typically E(b-y) = 0.020 in all its
extension, except towards the Mensa constellation where a possible transition
is observed at d = 200 +/- 20 pc. In the northernmost part the colour excess
increases with distance in a gradual way, such that 0.020 <= E(b-y) <= 0.040
mag becomes predominant only after d=120 +/-15 pc.
  If the ring really exists the colour excess distribution indicates that it is
very fragmented and distorted. However, the different characteristics of the
reddening inside and along the ring do not support the existence of a ring.


title: Rotational Doppler effect in left-handed materials

abstract:
  We explain the rotational Doppler effect associated with light beams carrying
with orbital angular momentum in left-handed materials (LHMs). We demonstrate
that the rotational Doppler effect in LHMs is unreversed, which is
significantly different from the linear Doppler effect. The physics underlying
this intriguing effect is the combined contributions of negative phase velocity
and inverse screw of wave-front. In the normal dispersion region, the
rotational Doppler effect induces a upstream energy flow but a downstream
momentum flow. In the anomalous dispersion region, however, the rotational
Doppler effect produces a downstream energy flow but a upstream momentum flow.
We theoretically predict that the rotational Doppler effect can induce a
transfer of angular momentum of the LHM to orbital angular momentum of the
beam.


title: Rotational mixing in close binaries

abstract:
  Rotational mixing is a very important but uncertain process in the evolution
of massive stars. We propose to use close binaries to test its efficiency.
Based on rotating single stellar models we predict nitrogen surface
enhancements for tidally locked binaries. Furthermore we demonstrate the
possibility of a new evolutionary scenario for very massive (M > 40 solar mass)
close (P < 3 days) binaries: Case M, in which mixing is so efficient that the
stars evolve quasi-chemically homogeneously, stay compact and avoid any
Roche-lobe overflow, leading to very close (double) WR binaries.


title: The ANTARES Neutrino Telescope: first results

abstract:
  The ANTARES Collaboration is completing the deployment of a 12 lines
underwater detector, 2500m deep in the Mediterranean Sea, dedicated to high
energy neutrino astronomy. Starting with the first line in 2006, 10 lines were
continuously recording data by the end of 2007, which allow us to reconstruct
downward-going cosmic muons, and search for the first upward-going
neutrino-induced muons. Calibration topics will be described and preliminary
results presented.


title: The role of electron-hole recombination in organic magnetoresistance

abstract:
  Magneto-electrical measurements were performed on diodes and bulk
heterojunction solar cells (BHSCs) to clarify the role of formation of
coulombically bound electron-hole (e-h) pairs on the magnetoresistance (MR)
response in organic thin film devices. BHSCs are suitable model systems because
they effectively quench excitons but the probability of forming e-h pairs in
them can be tuned over orders of magnitude by the choice of material and
solvent in the blend. We have systematically varied the e-h recombination
coefficients, which are directly proportional to the probability for the charge
carriers to meet in space, and found that a reduced probability of electrons
and holes meeting in space lead to disappearance of the MR. Our results clearly
show that MR is a direct consequence of e-h pair formation. We also found that
the MR line shape follows a power law-dependence of B0.5 at higher fields.


title: A nonlinear inequality

abstract:
  A quadratic inequality is formulated in the paper. An estimate on the rate of
decay of solutions to this inequality is obtained. This inequality is of
interest in a study of dynamical systems and nonlinear evolution equations.


title: GZK photon constraints on Planck scale Lorentz violation in QED

abstract:
  We show how the argument exploited by Galaverni & Sigl in Phys. Rev. Lett.,
100, 021102 (2008) (see also arXiv:0708.1737) to constrain Lorentz invariance
violation (LV) using Ultra-High-Energy photon non observation by the AUGER
experiment, can be extended to QED with Planck-suppressed LV (at order $O(E/M)$
and $O(E^2/M^2)$). While the original constraints given by Galaverni & Sigl
happen to be weakened, we show that, when used together with other EFT
reactions and the expected detection of photons at $E > 10^{19}$ eV by AUGER,
this method has the potentiality not only to basically rule out order $O(E/M)$
corrections but also to strongly constrain, for the first time, the CPT-even
$O(E^2/M^2)$ LV QED.


title: Creating Wave-Focusing Materials

abstract:
  Basic ideas for creating wave-focusing materials by injecting small particles
in a given material are described.
  The number of small particles to be injected around any point is calculated.
Inverse scattering problem with fixed wavenumber and fixed incident direction
of the plane acoustic wave is formulated and solved.


title: Complex Molecules in the L1157 Molecular Outflow

abstract:
  We report the detection of complex organic molecules in the young
protostellar outflow L1157. We identify lines from HCOOCH3, CH3CN, HCOOH and
C2H5OH at the position of the B1 shock in the blueshifted lobe, making it the
first time that complex species have been detected towards a molecular outflow
powered by a young low-mass protostar. The time scales associated with the warm
outflow gas (< 2,000 yr) are too short for the complex molecules to have formed
in the gas phase after the shock-induced sputtering of the grain mantles. It is
more likely that the complex species formed in the surface of grains and were
then ejected from the grain mantles by the shock. The formation of complex
molecules in the grains of low-mass star forming regions must be relatively
efficient, and our results show the importance of considering the impact of
outflows when studying complex molecules around protostars. The relative
abundance with respect to methanol of most of the detected complex molecules is
similar to that of hot cores and molecular clouds in the galactic center
region, which suggests that the mantle composition of the dust in the L1157
dark cloud is similar to dust in those regions.


title: Small Quarkonium states in an anisotropic QCD plasma

abstract:
  We determine the hard-loop resummed propagator in an anisotropic QCD plasma
in general covariant gauges and define a potential between heavy quarks from
the Fourier transform of its static limit. We find that the potential exhibits
angular dependence and that binding of very small quarkonium states is stronger
than in an isotropic plasma.


title: Halo mass - concentration relation from weak lensing

abstract:
  We perform a statistical weak lensing analysis of dark matter profiles around
tracers of halo mass from galactic- to cluster-size halos. In this analysis we
use 170,640 isolated ~L* galaxies split into ellipticals and spirals, 38,236
groups traced by isolated spectroscopic Luminous Red Galaxies (LRGs) and 13,823
MaxBCG clusters from the Sloan Digital Sky Survey (SDSS) covering a wide range
of richness. Together these three samples allow a determination of the density
profiles of dark matter halos over three orders of magnitude in mass, from
10^{12} M_{sun} to 10^{15} M_{sun}. The resulting lensing signal is consistent
with an NFW or Einasto profile on scales outside the central region. We find
that the NFW concentration parameter c_{200b} decreases with halo mass, from
around 10 for galactic halos to 4 for cluster halos. Assuming its dependence on
halo mass in the form of c_{200b} = c_0 [M/(10^{14}M_{sun}/h)]^{\beta}, we find
c_0=4.6 +/- 0.7 (at z=0.22) and \beta=0.13 +/- 0.07, with very similar results
for the Einasto profile. The slope (\beta) is in agreement with theoretical
predictions, while the amplitude is about two standard deviations below the
predictions for this mass and redshift, but we note that the published values
in the literature differ at a level of 10-20% and that for a proper comparison
our analysis should be repeated in simulations. We discuss the implications of
our results for the baryonic effects on the shear power spectrum: since these
are expected to increase the halo concentration, the fact that we see no
evidence of high concentrations on scales above 20% of the virial radius
suggests that baryonic effects are limited to small scales, and are not a
significant source of uncertainty for the current weak lensing measurements of
the dark matter power spectrum. [ABRIDGED]


title:
Impact of the symmetry energy on the outer crust of non-accreting
  neutron stars

abstract:
  The composition and equation of state of the outer crust of non-accreting
neutron stars is computed using accurate nuclear mass tables. The main goal of
the present study is to understand the impact of the symmetry energy on the
structure of the outer crust. First, a simple "toy model" is developed to
illustrate the competition between the electronic density and the symmetry
energy. Then, realistic mass tables are used to show that models with a stiff
symmetry energy - those that generate large neutron skins for heavy nuclei -
predict a sequence of nuclei that are more neutron-rich than their softer
counterparts. This result may be phrased in the form of a correlation: the
larger the neutron skin of 208Pb, the more exotic the composition of the outer
crust.


title: HELAS and MadGraph/MadEvent with spin-2 particles

abstract:
  Fortran subroutines to calculate helicity amplitudes with massive spin-2
particles (massive gravitons), which couple to the standard model particles via
the energy momentum tensor, are added to the {\tt HELAS} ({\tt HEL}icity {\tt
A}mplitude {\tt S}ubroutines) library. They are coded in such a way that
arbitrary scattering amplitudes with one graviton production and its decays can
be generated automatically by {\tt MadGraph} and {\tt MadEvent}, after slight
modifications. All the codes have been tested carefully by making use of the
invariance of the helicity amplitudes under the gauge and general coordinate
transformations.


title: Quantum black-hole information missing in the semiclassical treatment

abstract:
  In the semiclassical treatment of gravity, an external observer can measure
only the mean (not the exact) mass of the black hole (BH). By contrast, in
fully quantum gravity the exact (not only mean) BH mass is measurable by the
external observer. This additional information (missing in the semiclassical
treatment) available to the external observer significantly helps to understand
how information leaks out during the BH evaporation.


title: Trapping of lattice polarons by impurities

abstract:
  We consider the effects of single impurities on polarons in three-dimensions
(3D) using a continuous time quantum Monte-Carlo algorithm. An exact treatment
of the phonon degrees of freedom leads to a very efficient algorithm and we are
able to compute the polaron dynamics on an infinite lattice using an auxiliary
weighting scheme. The magnitude of the impurity potential, the electron-phonon
coupling and the phonon frequency are varied. We determine the magnitude of the
impurity potential required for polaron trapping. For small electron-phonon
coupling the number of phonons increases dramatically on trapping. The polaron
binding diagram is computed, showing that intermediate-coupling
low-phonon-frequency polarons are localized by exceptionally small impurities.


title: Cosmological spacetimes balanced by a scale covariant scalar field

abstract:
  A scale invariant, Weyl geometric, Lagrangian approach to cosmology is
explored, with a a scalar field phi of (scale) weight -1 as a crucial
ingredient besides classical matter \cite{Tann:Diss,Drechsler:Higgs}. For a
particularly simple class of Weyl geometric models (called {\em Einstein-Weyl
universes}) the Klein-Gordon equation for phi is explicitly solvable. In this
case the energy-stress tensor of the scalar field consists of a vacuum-like
term Lambda g_{mu nu} with variable coefficient Lambda, depending on matter
density and spacetime geometry, and of a dark matter like term. Under certain
assumptions on parameter constellations, the energy-stress tensor of the
phi-field keeps Einstein-Weyl universes in locally stable equilibrium. A short
glance at observational data, in particular supernovae Ia (Riess ea 2007),
shows interesting empirical properties of these models.


title:
Initial Value Problem of the Whitham Equations for the Camassa-Holm
  Equation

abstract:
  We study the Whitham equations for the Camassa-Holm equation. The equations
are neither strictly hyperbolic nor genuinely nonlinear. We are interested in
the initial value problem of the Whitham equations. When the initial values are
given by a step function, the Whitham solution is self-similar. When the
initial values are given by a smooth function, the Whitham solution exists
within a cusp in the x-t plane. On the boundary of the cusp, the Whitham
equation matches the Burgers solution, which exists outside the cusp.


title: Young star clusters in interacting galaxies - NGC 1487 and NGC 4038/4039

abstract:
  We estimate the dynamical masses of several young (~10 Myr) massive star
clusters in two interacting galaxies, NGC 4038/4039 ("The Antennae") and NGC
1487, under the assumption of virial equilibrium. These are compared with
photometric mass estimates from K-band photometry and assuming a standard
Kroupa IMF. The clusters were selected to have near-infrared colors dominated
by red supergiants, and hence to be old enough to have survived the earliest
phases of cluster evolution when the interstellar medium is rapidly swept out
from the cluster, supported by the fact that there is no obvious Halpha
emission associated with the clusters. All but one of the Antennae clusters
have dynamical and photometric mass estimates which are within a factor ~2 of
one another, implying both that standard IMFs provide a good approximation to
the IMF of these clusters, and that there is no significant extra-virial
motion, as would be expected if they were rapidly dispersing. These results
suggest that almost all of the Antennae clusters in our sample have survived
the gas removal phase as bound or marginally bound objects. Two of the three
NGC 1487 clusters studied here have M_dyn estimates which are significantly
larger than the photometric mass estimates. At least one of these two clusters,
and one in the Antennae, may be actively in the process of dissolving. The
process of dissolution contributes a component of non-virial motion to the
integrated velocity measurements, resulting in an estimated M_dyn which is too
high relative to the amount of measured stellar light. The dissolution
candidates in both galaxies are amongst the clusters with the lowest
pressures/densities measured in our sample.


title: Triaxiality in the interacting boson model

abstract:
  The signature splitting of the $\gamma$-vibrational band of several Ru, Pd,
Xe, Ba, Os and Pt isotopes is analyzed in the framework of the interacting
boson model (IBM). The nuclei studied are close to the $\gamma$-unstable SO(6)
limit of the IBM and have well-known $\gamma$ bands. It is shown that in most
nuclei the signature splitting is better reproduced by the inclusion of a
three-body interaction between the $d$ bosons. In none of the nuclei evidence
for a stable, triaxial ground-state shape is found.


title: Nuclear magic numbers: new features far from stability

abstract:
  The main purpose of the present manuscript is to review the structural
evolution along the isotonic and isotopic chains around the "traditional" magic
numbers 8; 20; 28; 50; 82 and 126. The exotic regions of the chart of nuclides
have been explored during the three last decades. Then the postulate of
permanent magic numbers was de nitely abandoned and the reason for these
structural mutations has been in turn searched for. General trends in the
evolution of shell closures are discussed using complementary experimental
information, such as the binding energies of the orbits bounding the shell
gaps, the trends of the rst collective states of the even-even semi-magic
nuclei, and the behavior of certain single-nucleon states. Each section is
devoted to a particular magic number. It describes the underlying physics of
the shell evolution which is not yet fully understood and indicates future
experimental and theoretical challenges. The nuclear mean eld embodies various
facets of the Nucleon- Nucleon interaction, among which the spin-orbit and
tensor terms play decisive roles in the shell evolutions. The present review
intends to provide experimental constraints to be used for the re nement of
theoretical models aiming at a good description of the existing atomic nuclei
and at more accurate predictions of hitherto unreachable systems.


title: Ergodicit\'e, collage et transport anomal

abstract:
  Nous nous int\'eressons \`a la convergence vers sa moyenne spatiale ergodique
de la moyenne temporelle d'une observable d'un flow hamiltonien \`a un degr\'e
et demi de libert\'e avec espace des phases mixte. L'analyse est faite au
travers de l'\'evolution de la distribution des moyennes en temps fini d'un
ensemble de conditions initiales sur la m\^eme composante ergodique. Un
exposant caract\'erisant la vitesse de convergence est d\'efini. Les
r\'esultats indiquent que pour le syst\`eme consid\'er\'e la convergence
\'evolue en $t^{\alpha}$, avec $\alpha=0.45$ pour alors qu'elle \'evolue en
$t^{1/2}$ lorsque la dynamique est globalement chaotique dans l'espace des
phases. De m\^eme une loi $\alpha=1-\beta/2$ reliant cet exposant $\alpha$ \`a
l'exposant caract\'eristique du deuxi\`eme moment associ\'e aux propri\'et\'es
de transport $\beta$ est propos\'ee et est v\'erifi\'ee pour les cas
consid\'er\'es.


title: The regular algebra of a poset

abstract:
  Let $K$ be a field. We attach to each finite poset $\mathbb P$ a von Neumann
regular $K$-algebra $Q_K(\mathbb P)$ in a functorial way. We show that the
monoid of isomorphism classes of finitely generated projective $Q_K(\mathbb
P)$-modules is the abelian monoid generated by $\mathbb P$ with the only
relations given by $p=p+q$ whenever $q<p$ in $\mathbb P$. This extends the
class of monoids for which there is a positive solution to the realization
problem for von Neumann regular rings.


title: On electrostatic modes in multi-ion and pair-ion collisional plasmas

abstract:
  The physics of plasmas containing positive and negative ions is discussed
with special attention to the recently produced pair-ion plasma containing ions
of equal mass and opposite charge. The effects of the density gradient in the
direction perpendicular to the ambient magnetic field vector, observed in the
experiment, are discussed. In addition, the possible presence of electrons is
discussed in the context of plasma modes propagating at an angle with respect
to the magnetic field vector. The electrons may either be added to the plasma
or enter the plasma attached to negative ions and then become released from the
ions as a result of collisions. It is shown that the electron plasma mode in a
cold plasma may become a backward mode in the presence of a density gradient,
and this behavior may be controlled either by the electron number density or
the mode number in the perpendicular direction. In plasmas with hot electrons
an instability may develop, driven by the combination of electron collisions
and the density gradient, and in the regime when the ions' response is similar
to a sound mode, i.e., for un-magnetized ions, implying mode frequencies much
above the ion gyro-frequency or mode wave-lengths shorter than the ion
gyro-radius. In the case of a pure pair-ion plasma, for lower frequencies and
for parameters close to those used in the recent experiments, the perturbed
ions may feel the effects of the magnetic field. In this case the plasma mode
also becomes backward, resembling features of an experimentally observed but
yet unexplained backward mode.


title:
Thermodynamic behaviour and structural properties of an aqueous sodium
  chloride solution upon supercooling

abstract:
  We present the results of a molecular dynamics simulation study of
thermodynamic and structural properties upon supercooling of a low
concentration sodium chloride solution in TIP4P water and the comparison with
the corresponding bulk quantities. We study the isotherms and the isochores for
both the aqueous solution and bulk water. The comparison of the phase diagrams
shows that thermodynamic properties of the solution are not merely shifted with
respect to the bulk. Moreover, from the analysis of the thermodynamic curves,
both the spinodal line and the temperatures of maximum density curve can be
calculated. The spinodal line appears not to be influenced by the presence of
ions at the chosen concentration, while the temperatures of maximum density
curve displays both a mild shift in temperature and a shape modification with
respect to bulk. Signatures of the presence of a liquid-liquid critical point
are found in the aqueous solution. By analysing the water-ion radial
distribution functions of the aqueous solution we observe that upon changing
density, structural modifications appear close to the spinodal. For low
temperatures additional modifications appear also for densities close to that
corresponding to a low density configurational energy minimum.


title:
Note on the role of friction-induced momentum conservation in the
  collisional drift wave instability

abstract:
  The collisional drift wave instability is reexamined taking into account the
ion response in the direction parallel to the magnetic field lines, which
appears due to friction with electrons and which can not be omitted in view of
the momentum conservation. A modified instability threshold is obtained. In
plasmas with dominant electron collisions with neutrals, the instability
threshold is shifted towards higher frequencies, compared to the case of
dominant electron collisions with ions. The difference between the two cases
vanishes when the ion sound response is negligible, i.e., when the instability
threshold disappears, and both ions and neutrals react to the electron friction
in the same manner.


title:
Cool Subdwarf Investigations (CSI) I: New Thoughts for the Spectral
  Types of K and M Subdwarfs

abstract:
  Using new spectra of 88 K and M-type subdwarfs, we consider novel methods for
assigning their spectral types and take steps toward developing a comprehensive
spectral sequence for subdwarf types K3.0 to M6.0. The types are assigned based
on the overall morphology of spectra covering 6000\AA to 9000\AA. The types and
sequence presented link the spectral types of cool subdwarfs to their main
sequence counterparts, with emphasis on the relatively opacity-free region from
8200--9000\AA. When available, supporting abundance, kinematic, and
trigonometric parallax information is used to provide more complete portraits
of the observed subdwarfs. We find that the CaHn (n $=$ 1--3) and TiO5 indices
often used for subdwarf spectral typing are affected in complicated ways by
combinations of subdwarfs' temperatures, metallicities, and gravities, and we
use model grids to evaluate the trends in all three parameters. Because of the
complex interplay of these three characteristics, it is not possible to
identify a star as an ``extreme'' subdwarf simply based on very low
metallicity, and we suggest that the modifiers ``extreme'' or ``ultra'' only
outline locations on spectroscopic indices plots, and should not be used to
imply low or very low metallicity stars. In addition, we propose that ``VI'' be
used to identify a star as a subdwarf, rather than the confusing ``sd'' prefix,
which is also used for hot O and B subdwarfs that are unrelated to the cool
subdwarfs discussed in this paper.


title: Ambiguity theory, old and new

abstract:
  This is a introductory survey of some recent developments of "Galois ideas"
in Arithmetic, Complex Analysis, Transcendental Number Theory and Quantum Field
Theory, and of some of their interrelations.


title: Galois theory, motives and transcendental numbers

abstract:
  From its early beginnings up to nowadays, algebraic number theory has evolved
in symbiosis with Galois theory: indeed, one could hold that it consists in the
very study of the absolute Galois group of the field of rational numbers.
  Nothing like that can be said of transcendental number theory. Nevertheless,
couldn't one associate conjugates and a Galois group to transcendental numbers
such as $\pi$? Beyond, can't one envision an appropriate Galois theory in the
field of transcendental number theory? In which role?
  The aim of this text is to indicate what Grothendieck's theory of motives has
to say, at least conjecturally, on these questions.


title: Hydrodynamics and beyond in the strongly coupled N=4 plasma

abstract:
  We continue our investigations on the relation between hydrodynamic and
higher quasinormal modes in the AdS black hole background started in
arXiv:0710.4458 [hep-th]. As is well known, the quasinormal modes can be
interpreted as the poles of the retarded Green functions of the dual N=4 gauge
theory at finite temperature. The response to a generic perturbation is
determined by the residues of the poles. We compute these residues numerically
for energy-momentum and R-charge correlators. We find that the diffusion modes
behave in a similar way: at small wavelengths the residues go over into a form
of a damped oscillation and therefore these modes decouple at short distances.
The sound mode behaves differently: its residue does not decay and at short
wavelengths this mode behaves as the higher quasinormal modes. Applications of
our findings include the definition of hydrodynamic length and time scales. We
also show that the quasinormal modes, including the hydrodynamic diffusion
modes, obey causality.


title: Superfluid Bose gas in two dimensions

abstract:
  We investigate Bose-Einstein condensation for ultracold bosonic atoms in
two-dimensional systems. The functional renormalization group for the average
action allows us to follow the effective interactions from molecular scales
(microphysics) to the characteristic extension of the probe $l$ (macrophysics).
In two dimensions the scale dependence of the dimensionless interaction
strength $\lambda$ is logarithmic. Furthermore, for large $l$ the frequency
dependence of the inverse propagator becomes quadratic. We find an upper bound
for $\lambda$, and for large $\lambda$ substantial deviations from the
Bogoliubov results for the condensate depletion, the dispersion relation and
the sound velocity. The melting of the condensate above the critical
temperature $T_c$ is associated to a phase transition of the
Kosterlitz-Thouless type. The critical temperature in units of the density,
$T_c/n$, vanishes for $l\to\infty$ logarithmically.


title: Triangulordinary Selmer Groups

abstract:
  Let $p$ be a prime number, and let $K$ be a $p$-adic local field. We study a
class of semistable $p$-adic Galois representations of $K$, which we call {\it
triangulordinary} because it includes the ordinary ones yet allows non-\'etale
behavior in the associated $(\phi,\Gamma_K)$-modules over the Robba ring. Our
main result provides a description of the Bloch--Kato local condition of such
representations. We also propose a program, using variational techniques, that
would give a definition of the Selmer group along the eigencurve of
Coleman--Mazur, including notably its nonordinary locus.


title: Extended Symmetries in Supergravity: the Semi-simple Case

abstract:
  The bosonic sector of various supergravity theories reduces to a homogeneous
space G/H in three dimensions. The corresponding algebras g are simple for
(half-)maximal supergravity, but can be semi-simple for other theories. We
extend the existing literature on the Kac-Moody extensions of simple Lie
algebras to the semi-simple case. Furthermore, we argue that for N=2
supergravity the simple algebras have to be augmented with an su(2) factor.


title: Nilpotent centralizers and Springer isomorphisms

abstract:
  Let G be a semisimple algebraic group over a field K whose characteristic is
very good for G, and let sigma be any G-equivariant isomorphism from the
nilpotent variety to the unipotent variety; the map sigma is known as a
Springer isomorphism. Let y in G(K), let Y in Lie(G)(K), and write C_y = C_G(y)
and C_Y= C_G(Y) for the centralizers. We show that the center of C_y and the
center of C_Y are smooth group schemes over K. The existence of a Springer
isomorphism is used to treat the crucial cases where y is unipotent and where Y
is nilpotent.
  Now suppose G to be quasisplit, and write C for the centralizer of a rational
regular nilpotent element. We obtain a description of the normalizer N_G(C) of
C, and we show that the automorphism of Lie(C) determined by the differential
of sigma at zero is a scalar multiple of the identity; these results verify
observations of J-P. Serre.


title: A semi-quantitative scattering theory of amorphous materials

abstract:
  It is argued that topological disorder in amorphous solids can be described
by local strains related to local reference crystals and local rotations. An
intuitive localization criterion is formulated from this point of view. The
Inverse Participation Ratio and the location of mobility edges in band tails is
directly related to the character of the disorder potential in amorphous solid,
the coordination number, the transition integral and the nodes of wave
functions of the corresponding reference crystal. The dependence of the decay
rate of band tails on temperature and static disorder are derived. \textit{Ab
initio} simulations on a-Si and experiments on a-Si:H are compared to these
predictions.


title: Relative rates of B meson decays into psi(2S) and J/psi mesons

abstract:
  We report on a study of the relative rates of B meson decays into psi(2S) and
J/psi mesons using 1.3 fb^-1 of pbar p collisions at sqrt(s) = 1.96 TeV
recorded by the D0 detector operating at the Fermilab Tevatron Collider. We
observe the channels B^0_s -> psi(2S)phi, B^0_s -> J/psi phi, B^+/- -> psi(2S)
K^+/-, and B^+/- -> J/psi K^+/- and we measure the relative branching fractions
for these channels to be B(B^0_s -> psi(2S)phi)/B(B^0_s -> J/psi phi) = 0.55
+/- 0.11 (stat) +/- 0.07 (syst) +/- 0.06 (B), B(B^+/- -> psi(2S) K^+/-)/B(B^+/-
-> J/psi K^+/-) = 0.65 +/- 0.04 (stat) +/- 0.03 (syst) +/- 0.07 (B) where the
final error corresponds to the uncertainty in the J/psi and psi(2S) branching
ratio into two muons.


title:
INTEGRAL observations of the blazar Mrk 421 in outburst (Results of a
  multi-wavelength campaign)

abstract:
  We report the results of a multi-wavelength campaign on the blazar Mrk 421
during outburst. We observed four strong flares at X-ray energies that were not
seen at other wavelengths (partially because of missing data). From the fastest
rise in the X-rays, an upper limit could be derived on the extension of the
emission region. A time lag between high-energy and low-energy X-rays was
observed, which allowed an estimation of the magnetic-field strength. The
spectral analysis of the X-rays revealed a slight spectral hardening of the
low-energy (3 - 43 keV) spectral index. The hardness-ratio analysis of the
Swift-XRT (0.2 - 10 keV) data indicated a small correlation with the intensity;
i. e., a hard-to-soft evolution was observed. At the energies of IBIS/ISGRI (20
- 150 keV), such correlations are less obvious. A multiwavelength spectrum was
composed and the X-ray and bolometric luminosities are calculated.


title:
Comment on ``Comparative study of Higgs transition in one-component and
  two-component lattice superconductor models"

abstract:
  We comment on the claim of continuous phase transition in the SU(2) symmetric
Deconfined Critical Point action made by O.Motrunich and A.Vishwanath in
ArXive:0805.1494


title:
Fundamentals of Non-relativistic Collisionless Shock Physics: IV.
  Quasi-Parallel Supercritical Shocks

abstract:
  1. Introduction, 2. The (quasi-parallel) foreshock; Ion foreshock, Ion
foreshock boundary region; Diffuse ions;Low-frequency upstream waves; Ion beam
waves; The expected wave modes; Observations; Diffuse ion waves; Electron
foreshock; Electron beams; Langmuir waves; stability of the electron beam;
Electron foreshock boundary waves; Nature of electron foreshock waves;
Radiation; Observations; Interpretation; 3. Quasi-parallel shock reformation;
Low-Mach number quasi-parallel shocks; Turbulent reformation; Observations;
Simulations of quasi-parallel shock reformation; Hybrid simulations in 1D;
Hybrid simulations in 2D; Full particle PIC simulations; Conclusions; 4. Hot
flow anomalies; Observations; Models and simulations; Solitary shock; 5.
Downstream region; 6. Summary and conclusions.


title: Nonlinear Femtosecond Pulse Reshaping in Waveguide Arrays

abstract:
  We observe nonlinear pulse reshaping of femtosecond pulses in a waveguide
array due to coupling between waveguides. Amplified pulses from a mode-locked
fiber laser are coupled to an AlGaAs core waveguide array structure. The
observed power-dependent pulse reshaping agrees with theory, including
shortening of the pulse in the central waveguide.


title: Lines on hypersurfaces

abstract:
  This is a detailed study of the infinitesimal variation of the variety of
lines through a point of a low degree hypersurface in pro jective space. The
motion is governed by a system of partial differential equations which we
describe explicitly.


title:
Variational Monte-Carlo calculation of the nematic state of the
  two-dimensional electron gas in a magnetic field

abstract:
  We use a Jastrow-Slater wave function with an elliptical Fermi sea to
describe the nematic state of the two-dimensional electron gas in a magnetic
field and the Monte Carlo method to calculate a variational energy upper bound.
These energy upper bounds are compared with other upper bounds describing
stripe-ordered ground states which are obtained from optimized Hartree-Fock
calculations and with those which correspond to an isotropic ground state. Our
findings support the conclusions drawn in our previous study where the
Fermi-hypernetted chain approximation was used instead of the Monte Carlo
method. Namely, the nematic state becomes energetically favorable relative to
the stripe-ordered Wigner crystal phase for the second excited Landau level and
below a critical value of the layer ``thickness'' parameter which is very close
to its value in the actual materials.


title:
Can Solar Neutrinos be a Serious Background in Direct Dark Matter
  Searches?

abstract:
  The coherent contribution of all neutrons in neutrino nucleus scattering due
to the neutral current is examined considering the boron solar neutrinos. These
neutrinos could potentially become a source of background in the future dark
matter searches aiming at nucleon cross sections in the region well below the
few events per ton per year.


title: Is Physics Asking for a New Kinematics?

abstract:
  It is discussed whether some of the consistency problems of present-day
physics could be solved by replacing special relativity, whose underlying
kinematics is ruled by the Poincare' group, by de Sitter relativity, with
underlying kinematics ruled by the de Sitter group. In contrast to ordinary
special relativity, which seems to fail at the Planck scale, this new
relativity is "universal" in the sense that it holds at all energy scales.


title: Tunneling Spectra of Individual Magnetic Endofullerene Molecules

abstract:
  The manipulation of single magnetic molecules may enable new strategies for
high-density information storage and quantum-state control. However, progress
in these areas depends on developing techniques for addressing individual
molecules and controlling their spin. Here we report success in making
electrical contact to individual magnetic N@C60 molecules and measuring spin
excitations in their electron tunneling spectra. We verify that the molecules
remain magnetic by observing a transition as a function of magnetic field which
changes the spin quantum number and also the existence of nonequilibrium
tunneling originating from low-energy excited states. From the tunneling
spectra, we identify the charge and spin states of the molecule. The measured
spectra can be reproduced theoretically by accounting for the exchange
interaction between the nitrogen spin and electron(s) on the C60 cage.


title: A possible optical counterpart to the old nearby pulsar J0108-1431

abstract:
  The multi-wavelength study of old (>100 Myr) radio pulsars holds the key to
understanding the long-term evolution of neutron stars, including the advanced
stages of neutron star cooling and the evolution of the magnetosphere.
Optical/UV observations are particularly useful for such studies because they
allow one to explore both thermal and non-thermal emission processes. In
particular, studying the optical/UV emission constrains temperature of the bulk
of the neutron star surface, too cold to be measured in X-ray observations.Aim
of this work is to identify the optical counterpart of the very old (166 Myr)
radio pulsar J0108-1431. We have re-analyzed our original VLT observations
(Mignani et al. 2003), where a very faint object was tentatively detected close
to the radio position, near the edge of a field galaxy. We found that the
backward extrapolation of the PSR J0108-1431 proper motion recently measured by
CHANDRA(Pavlov et al. 2008) nicely fits the position of this object. Based on
that, we propose it as a viable candidate for the optical counterpart to PSR
J0108-1431. The object fluxes (U =26.4+/-0.3; B =27.9; V >27.8) are consistent
with a thermal spectrum with a brightness temperature of 9X10^4 K (for R = 13
km at a distance of 130 pc), emitted from the bulk of the neutron star surface.
New optical observations are required to confirm the optical identification of
PSR J0108-1431 and measure its spectrum.


title: The Yang-Mills stratification for surfaces revisited

abstract:
  We revisit Atiyah and Bott's study of Morse theory for the Yang-Mills
functional over a Riemann surface, and establish new formulas for the minimum
codimension of a (non-semi-stable) stratum. These results yield the exact
connectivity of the natural map (C_{min} E)//G(E) --> Map^E (M, BU(n)) from the
homotopy orbits of the space of central Yang-Mills connections to the
classifying space of the gauge group G(E). All of these results carry over to
non-orientable surfaces via Ho and Liu's non-orientable Yang-Mills theory.
  A somewhat less detailed version of this paper (titled "On the Yang-Mills
stratification for surfaces") will appear in the Proceedings of the AMS.


title: The parton model

abstract: I give a brief review of the parton model.


title: Stochastic Electron Acceleration in Shell-Type Supernova Remnants

abstract:
  We study the stochastic electron acceleration by fast mode waves in the
turbulent downstream of weakly magnetized collisionless astrophysical shocks.
The acceleration is most efficient in a dissipative layer, and the model
characteristics are determined by the shock speed, density, magnetic field, and
turbulence decay length. The model explains observations of shell-type
supernova remnants RX J1713.7-3946 and J0852.0-4622 and can be tested by
observations in hard X-rays with the HXMT and NuSTAR or gamma-rays with the
GLAST.


title: On Two Related Questions of Wilf Concerning Standard Young Tableaux

abstract:
  We consider two questions of Wilf related to Standard Young Tableaux. We
provide a partial answer to one question, and that will lead us to a more
general answer to the other question. Our answers are purely combinatorial.


title: New Quarkonium Results from the BABAR experiment

abstract:
  New BABAR results on B mesons and quarkonia are presented: an analysis of B+
--> X(3872)K+ and B0 --> X(3872)K0 decays with X(3872) --> J/Psi pi+pi-, a
precise measurement of the B mass difference Delta mB = m(B0) - m(B+) and a
study of hadronic transition between Upsilon mesons.


title: Classicality of spin states

abstract:
  We extend the concept of classicality in quantum optics to spin states. We
call a state ``classical'' if its density matrix can be decomposed as a
weighted sum of angular momentum coherent states with positive weights.
Classical spin states form a convex set C, which we fully characterize for a
spin-1/2 and a spin-1. For arbitrary spin, we provide ``non-classicality
witnesses''. For bipartite systems, C forms a subset of all separable states. A
state of two spins-1/2 belongs to C if and only if it is separable, whereas for
a spin-1/2 coupled to a spin-1, there are separable states which do not belong
to C. We show that in general the question whether a state is in C can be
answered by a linear programming algorithm.


title: Complex domain wall dynamics in compressively strained GaMnAs epilayers

abstract:
  The domain wall induced reversal dynamics in compressively strained GaMnAs
was studied employing the magneto-optical Kerr effect and Kerr microscopy. Due
to the influence of an uniaxial part in the in-plane magnetic anisotropy
(90+/-Delta) domain walls with considerably different dynamic behavior are
observed. While the (90+Delta) reversal is identified to be propagation
dominated with a small number of domain walls, the case of (90-Delta) reversal
includes the nucleation of many domain walls. The domain wall
nucleation/propagation energy for both transitions are estimated using model
calculations from which we conclude that single domain devices can be
achievable using the (90+Delta) mode.


title: Discovery of Highly Obscured Galaxies in the Zone of Avoidance

abstract:
  We report the discovery of twenty-five previously unknown galaxies in the
Zone of Avoidance. Our systematic search for extended extra-galactic sources in
the GLIMPSE and MIPSGAL mid-infrared surveys of the Galactic plane has revealed
two overdensities of these sources, located around l ~ 47 and 55 degrees and
|b| less than 1 degree in the Sagitta-Aquila region. These overdensities are
consistent with the local large-scale structure found at similar Galactic
longitude and extending from |b| ~ 4 to 40 degrees. We show that the infrared
spectral energy distribution of these sources is indeed consistent with those
of normal galaxies. Photometric estimates of their redshift indicate that the
majority of these galaxies are found in the redshift range z = 0.01 - 0.05,
with one source located at z = 0.07. Comparison with known sources in the local
Universe reveals that these galaxies are located at similar overdensities in
redshift space. These new galaxies are the first evidence of a bridge linking
the large-scale structure between both sides of the Galactic plane at very low
Galactic latitude and clearly demonstrate the feasibility of detecting galaxies
in the Zone of Avoidance using mid-to-far infrared surveys.


title: $^{75}$As NMR studies of superconducting LaO$_{0.9}$F$_{0.1}$FeAs

abstract:
  We have performed 75As Nuclear Magnetic Resonance (NMR) measurements on
aligned powders of the new LaO0.9F0.1FeAs superconductor. In the normal state,
we find a strong temperature dependence of the spin shift and Korringa behavior
of the spin lattice relaxation rate. In the superconducting state, we find
evidence for line nodes in the superconducting gap and spin-singlet pairing.
Our measurements reveal a strong anisotropy of the spin lattice relaxation
rate, which suggest that superconducting vortices contribute to the relaxation
rate when the field is parallel to the c-axis but not for the perpendicular
direction.


title: Scalar perturbations in DGP braneworld cosmology

abstract:
  We solve for the behaviour of cosmological perturbations in the
Dvali-Gabadadze-Porrati (DGP) braneworld model using a new numerical method.
Unlike some other approaches in the literature, our method uses no
approximations other than linear theory and is valid on large scales. We
examine the behaviour of late-universe density perturbations for both the
self-accelerating and normal branches of DGP cosmology.


title: Absolute neutrino mass from helicity measurements

abstract:
  The possibility to access the absolute neutrino mass scale through the
measurement of the wrong helicity contribution of charged leptons is
investigated in pion decay. Through this method, one may have access to the
same effective mass $m^2_\beta$ extractable from the tritium beta decay
experiments for electron neutrinos as well as the analogous effective mass
$(m^2_{\nu_\mu})_{\rm eff}$ for muon neutrinos. In the channel $\pi^-\to
e^-\bar{\nu}$, the relative probability of producing an antineutrino with left
helicity is enhanced if compared with the naive expectation $(m_\nu/2E_\nu)^2$.
The possibility to constrain new interactions in the context of
Two-Higgs-Doublet models is also investigated.


title:
Overcrowding and hole probabilities for random zeros on complex
  manifolds

abstract:
  We give asymptotic large deviations estimates for the volume inside a domain
U of the zero set of a random polynomial of degree N, or more generally, of a
holomorphic section of the N-th power of a positive line bundle on a compact
Kaehler manifold. In particular, we show that for all $\delta>0$, the
probability that this volume differs by more than $\delta N$ from its average
value is less than $\exp(-C_{\delta,U}N^{m+1})$, for some constant
$C_{\delta,U}>0$. As a consequence, the "hole probability" that a random
section does not vanish in U has an upper bound of the form
$\exp(-C_{U}N^{m+1})$.


title: Concurrent $\pi$-vector fields and energy beta-change

abstract:
  The present paper deals with an \emph{intrinsic} investigation of the notion
of a concurrent $\pi$-vector field on the pullback bundle of a Finsler manifold
$(M,L)$. The effect of the existence of a concurrent $\pi$-vector field on some
important special Finsler spaces is studied. An intrinsic investigation of a
particular $\beta$-change, namely the energy $\beta$-change
($\widetilde{L}^{2}(x,y)=L^{2}(x,y)+ B^{2}(x,y) with \
B:=g(\bar{\zeta},\bar{\eta})$; $\bar{\zeta} $ being a concurrent $\pi$-vector
field), is established. The relation between the two Barthel connections
$\Gamma$ and $\widetilde{\Gamma}$, corresponding to this change, is found. This
relation, together with the fact that the Cartan and the Barthel connections
have the same horizontal and vertical projectors, enable us to study the energy
$\beta$-change of the fundamental linear connection in Finsler geometry: the
Cartan connection, the Berwald connection, the Chern connection and the
Hashiguchi connection. Moreover, the change of their curvature tensors is
concluded.
  It should be pointed out that the present work is formulated in a prospective
modern coordinate-free form.


title:
WASP-7: The brightest transiting-exoplanet system in the Southern
  hemisphere

abstract:
  We report that a Jupiter-mass planet, WASP-7b, transits the V = 9.5 star
HD197286 every 4.95 d. This is the brightest discovery from the WASP-South
transit survey and the brightest transiting-exoplanet system in the Southern
hemisphere. WASP-7b is among the densest of the known Jupiter-mass planets,
suggesting that it has a massive core. The planet mass is 0.96 M_Jup, the
radius 0.915 R_Jup, and the density 1.26 rho_Jup.


title: Holographic Spectral Functions at Finite Baryon Density

abstract:
  Using the AdS/CFT correspondence, we compute the spectral functions of
thermal super Yang Mills at large N_c coupled to a small number of flavours of
fundamental matter, N_f<<N_c, in the presence of a nonzero baryon density. The
holographic dual of such a theory involves the addition of probe D7-branes with
a background worldvolume gauge field switched on, embedded in the geometry of a
stack of black D3-branes. We perform the analysis in the vector and scalar
channels which become coupled for nonzero values of the spatial momentum and
baryon density. In addition, we obtain the effect of the presence of net baryon
charge on the photon production. We also extract the conductivity and find
perfect agreement with the results derived by Karch and O'Bannon in a
macroscopic setup.


title: On the homotopy theory of spectral categories

abstract:
  This paper has been withdrawn by the author, due a critical mistake on page
3.


title:
Proton structure corrections to electronic and muonic hydrogen hyperfine
  splitting

abstract:
  We present a precise determination of the polarizability and other proton
structure dependent contributions to the hydrogen hyperfine splitting, based
heavily on the most recent published data on proton spin dependent structure
functions from the EG1 experiment at the Jefferson Laboratory. As a result, the
total calculated hyperfine splitting now has a standard deviation slightly
under 1 part-per-million, and is about 1 standard deviation away from the
measured value. We also present results for muonic hydrogen hyperfine
splitting, taking care to ensure the compatibility of the recoil and
polarizability terms.


title:
ABCD Matrices as Similarity Transformations of Wigner Matrices and
  Periodic Systems in Optics

abstract:
  The beam transfer matrix, often called the $ABCD$ matrix, is a two-by-two
matrix with unit determinant, and with three independent parameters. It is
noted that this matrix cannot always be diagonalized. It can however be brought
by rotation to a matrix with equal diagonal elements. This equi-diagonal matrix
can then be squeeze-transformed to a rotation, to a squeeze, or to one of the
two shear matrices. It is noted that these one-parameter matrices constitute
the basic elements of the Wigner's little group for space-time symmetries of
elementary particles. Thus every $ABCD$ matrix can be written as a similarity
transformation of one of the Wigner matrices, while the transformation matrix
is a rotation preceded by a squeeze. This mathematical property enables us to
compute scattering processes in periodic systems. Laser cavities and multilayer
optics are discussed in detail. For both cases, it is shown possible to write
the one-cycle transfer matrix as a similarity transformation of one of the
Wigner matrices. It is thus possible to calculate the $ABCD$ matrix for an
arbitrary number of cycles.

categories: math-ph cond-mat.mtrl-sci hep-th math.MP


title: Separating algebras and finite reflection groups

abstract:
  A separating algebra is, roughly speaking, a subalgebra of the ring of
invariants whose elements distinguish between any two orbits that can be
distinguished using invariants. In this paper, we introduce a geometric notion
of separating algebra. This allows us to prove that only groups generated by
reflections may have polynomial separating algebras, and only groups generated
by bireflections may have complete intersection separating algebras.


title: Electromagnetic energy-momentum tensors in media

abstract:
  It is pointed out that the previous energy-momentum tensors of Minkowski and
Abraham for the electromagnetic field in continuous media are based on a
covariant formulation which does not reflect a symmetry inherent to the system.
Instead, taking into account the intrinsic invariance under Lorentz
transformations involving the reduced speed of light in such a medium, a
compact and fully consistent theory can be formulated without the old problems.


title:
Iron-60 evidence for early injection and efficient mixing of stellar
  debris in the protosolar nebula

abstract:
  Among extinct radioactivities present in meteorites, 60Fe (t1/2 = 1.49 Myr)
plays a key role as a high-resolution chronometer, a heat source in
planetesimals, and a fingerprint of the astrophysical setting of solar system
formation. A critical issue with 60Fe is that it could have been
heterogeneously distributed in the protoplanetary disk, calling into question
the efficiency of mixing in the solar nebula or the timing of 60Fe injection
relative to planetesimal formation. If this were the case, one would expect
meteorites that did not incorporate 60Fe (either because of late injection or
incomplete mixing) to show 60Ni deficits (from lack of 60Fe decay) and
collateral effects on other neutron-rich isotopes of Fe and Ni (coproduced with
60Fe in core-collapse supernovae and AGB-stars). Here, we show that measured
iron meteorites and chondrites have Fe and Ni isotopic compositions identical
to Earth. This demonstrates that 60Fe must have been injected into the
protosolar nebula and mixed to less than 10 % heterogeneity before formation of
planetary bodies.


title: High energy radiation from Centaurus A

abstract:
  We calculate for the nearest active galactic nucleus (AGN), Centaurus A, the
flux of high energy cosmic rays and of accompanying secondary photons and
neutrinos expected from hadronic interactions in the source. We use as two
basic models for the generation of ultrahigh energy cosmic rays (UHECR) shock
acceleration in the radio jet and acceleration in the regular electromagnetic
field close to the core of the AGN. While scattering on photons dominates in
scenarios with acceleration close to the core, scattering on gas becomes more
important if acceleration takes place along the jet. Normalizing the UHECR flux
from Centaurus A to the observations of the Auger experiment, the neutrino flux
may be marginally observable in a 1 km$^3$ neutrino telescope, if a steep UHECR
flux $\d N/\d E\propto E^{-\alpha}$ with $\alpha=2.7$ extends down to $10^{17}$
eV. The associated photon flux is close to or exceeds the observational data of
atmospheric Cherenkov and $\gamma$-ray telescopes for $\alpha\gsim 2$. In
particular, we find that already present data favour either a softer UHECR
injection spectrum than $\alpha=2.7$ for Centaurus A or a lower UHECR flux than
expected from the normalization to the Auger observations.


title:
Imprints of recoiling massive black-holes on the hot gas of early type
  galaxies

abstract:
  Anisotropic gravitational radiation from a coalescing black hole binary is
known to impart recoil velocities of up to ~1000 km/s to the remnant black
hole. In this context, we study the motion of a recoiling black hole inside a
galaxy modelled as an Hernquist sphere, and the signature that the hole
imprints on the hot gas, using N-body/SPH simulations. Ejection of the black
hole results in a sudden expansion of the gas ending with the formation of a
gaseous core, similarly to what is seen for the stars. A cometary tail of
particles bound to the black hole is initially released along its trail. As the
black hole moves on a return orbit, a nearly spherical swarm of hot gaseous
particles forms at every apocentre: this feature can live up to ~ 100 Myr. If
the recoil velocity exceeds the sound speed initially, the black hole shocks
the gas in the form of a Mach cone in density near each super-sonic pericentric
passage. We find that the X-ray fingerprint of a recoiling black hole can be
detected in Chandra X-ray maps out to a distance of Virgo. For exceptionally
massive black holes the Mach cone and the wakes could be observed out to a few
hundred of Mpc. Detection of the Mach cone is found to become of twofold
importance: i) as a probe of high-velocity recoils and ii) as an assessment of
the scatter of the mass-sigma relation at large black hole masses.


title:
Instability in cosmological topologically massive gravity at the chiral
  point

abstract:
  We consider cosmological topologically massive gravity at the chiral point
with positive sign of the Einstein-Hilbert term. We demonstrate the presence of
a negative energy bulk mode that grows linearly in time. Unless there are
physical reasons to discard this mode, this theory is unstable. To address this
issue we prove that the mode is not pure gauge and that its negative energy is
time-independent and finite. The isometry generators L_0 and \bar{L}_0 have
non-unitary matrix representations like in logarithmic CFT. While the new mode
obeys boundary conditions that are slightly weaker than the ones by Brown and
Henneaux, its fall-off behavior is compatible with spacetime being
asymptotically AdS_3. We employ holographic renormalization to show that the
variational principle is well-defined. The corresponding Brown-York stress
tensor is finite, traceless and conserved. Finally we address possibilities to
eliminate the instability and prospects for chiral gravity.


title: A model category structure on the category of simplicial multicategories

abstract:
  We establish a Quillen model category structure on the category of symmetric
simplicial multicategories. This model structure extends the model structure on
simplicial categories due to J. Bergner.


title: Galaxy Zoo: the dependence of morphology and colour on environment

abstract:
  We analyse the relationships between galaxy morphology, colour, environment
and stellar mass using data for over 100,000 objects from Galaxy Zoo, the
largest sample of visually classified morphologies yet compiled. We
conclusively show that colour and morphology fractions are very different
functions of environment. Both are sensitive to stellar mass; however, at fixed
stellar mass, while colour is also highly sensitive to environment, morphology
displays much weaker environmental trends. Only a small part of both relations
can be attributed to variation in the stellar mass function with environment.
Galaxies with high stellar masses are mostly red, in all environments and
irrespective of their morphology. Low stellar-mass galaxies are mostly blue in
low-density environments, but mostly red in high-density environments, again
irrespective of their morphology. The colour-density relation is primarily
driven by variations in colour fractions at fixed morphology, in particular the
fraction of spiral galaxies that have red colours, and especially at low
stellar masses. We demonstrate that our red spirals primarily include galaxies
with true spiral morphology. We clearly show there is an environmental
dependence for colour beyond that for morphology. Before using the Galaxy Zoo
morphologies to produce the above results, we first quantify a luminosity-,
size- and redshift-dependent classification bias that affects this dataset, and
probably most other studies of galaxy population morphology. A correction for
this bias is derived and applied to produce a sample of galaxies with reliable
morphological type likelihoods, on which we base our analysis.


title: Microscopic atom optics: from wires to an atom chip

abstract:
  We give a comprehensive overview of the development of micro traps, from the
first experiments on guiding atoms using current carrying wires in the early
1990's to the creation of a BEC on an atom chip.


title:
Measurement of the lifetime of the B_c meson in the semileptonic decay
  channel

abstract:
  Using approximately 1.3 fb-1 of data collected by the D0 detector between
2002 and 2006, we measure the lifetime of the B_c meson in the B_c -> J/psi mu
nu X final state. A simultaneous unbinned likelihood fit to the J/\psi+mu
invariant mass and lifetime distributions yields a signal of 881 +/- 80 (stat)
candidates and a lifetime measurement of \tau(B_c) = 0.448 +0.038 -0.036 (stat)
+/- 0.032 (syst) ps.


title:
The ChaMP Extended Stellar Survey (ChESS): Photometric and Spectroscopic
  Properties of Serendipitously Detected Stellar X-ray Sources

abstract:
  We present 348 X-ray emitting stars identified from correlating the Extended
Chandra Multiwavelength Project (ChaMP), a serendipitous wide-area X-ray
survey, with the Sloan Digital Sky Survey (SDSS). We use morphological
star/galaxy separation, an SDSS quasar catalog, an optical color-magnitude cut,
and X-ray data quality tests to create our catalog, the ChaMP Extended Stellar
Survey (ChESS), from a sample of 2121 matched ChaMP/SDSS sources. Our cuts
retain 92% of the spectroscopically confirmed stars while excluding 99.6% of
the 684 spectoscopically confirmed extragalactic sources. Fewer than 3% of the
sources in our final catalog are previously identified stellar X-ray emitters;
we expect ~10% of the catalog is composed by giants, and identify seven giant
stars and three cataclysmic variables. We derive distances, X-ray and
bolometric luminosities for these stars, revealing that this catalog fills the
gap between the nearby stars identified by the ROSAT All-Sky Survey and the
more distant stars detected in deep Chandra and XMM-Newton surveys. For 36
newly identified X-ray emitting M stars we calculate L_(Halpha)/L_(bol).
L_(H\alpha)/L_(bol) and L_(X)/L_(bol) are linearly related below L_(X)/L_(bol)
~ 3 x 10^(-4), while L_(Halpha)/L_(bol) appears to turn over at larger
L_(X)/L_(bol) values. Stars with reliable SDSS photometry have an ~0.1 mag blue
excess in (u-g), likely due to increased chromospheric continuum emission.
Photometric metallicity estimates suggest the sample is split between the young
and old disk populations of the Galaxy; the lowest activity sources belong to
the old disk population, a clear signature of the decay of magnetic activity
with age. Future papers will present analyses of source variability and
comparisons of this catalog to models of stellar activity in the Galactic disk.


title: Direct simulations of a supernova-driven galactic dynamo

abstract:
  Supernovae are known to be the dominant energy source for driving turbulence
in the interstellar medium. Yet, their effect on magnetic field amplification
in spiral galaxies is still poorly understood. Previous analytical models,
based on the evolution of isolated, non-interacting supernova remnants,
predicted a dominant vertical pumping that would render dynamo action
improbable. In the present work, we address the issue of vertical transport,
which is thought to be the key process that inhibits dynamo action in the
galactic context. We aim to demonstrate that supernova driving is a powerful
mechanism to amplify galactic magnetic fields. We conduct direct numerical
simulations in the framework of resistive magnetohydrodynamics. Our local box
model of the interstellar medium comprises optically-thin radiative cooling, an
external gravitational potential, and background shear. Dynamo coefficients for
mean-field models are measured by means of passive test fields. Our simulations
show that supernova-driven turbulence in conjunction with shear leads to an
exponential amplification of the mean magnetic field. We found turbulent
pumping to be directed inward and approximately balanced by a galactic wind.