title:
Scaling analysis of normal state properties of high-temperature
  superconductors

abstract:
  We propose a model-independent scaling method to study the physical
properties of high-temperature superconductors in the normal state. We have
analyze the experimental data of the c-axis resistivity, the in-plane
resistivity, the Hall coefficient, the magnetic susceptibility, the
spin-lattice relaxation rate, and the thermoelectric power using this method.
It is shown that all these physical quantities exhibit good scaling behaviors,
controlled purely by the pseudogap energy scale in the normal state. The doping
dependence of the pseudogap obtained from this scaling analysis agrees with the
experimental results of angle-resolved photoemission and other measurements. It
sheds light on the understanding of the basic electronic structure of high-Tc
oxides.


title: Gain Stabilization of a Submillimeter SIS Heterodyne Receiver

abstract:
  We have designed a system to stabilize the gain of a submillimeter heterodyne
receiver against thermal fluctuations of the mixing element. In the most
sensitive heterodyne receivers, the mixer is usually cooled to 4 K using a
closed-cycle cryocooler, which can introduce ~1% fluctuations in the physical
temperature of the receiver components. We compensate for the resulting mixer
conversion gain fluctuations by monitoring the physical temperature of the
mixer and adjusting the gain of the intermediate frequency (IF) amplifier that
immediately follows the mixer. This IF power stabilization scheme, developed
for use at the Submillimeter Array (SMA), a submillimeter interferometer
telescope on Mauna Kea in Hawaii, routinely achieves a receiver gain stability
of 1 part in 6,000 (rms to mean). This is an order of magnitude improvement
over the typical uncorrected stability of 1 part in a few hundred. Our gain
stabilization scheme is a useful addition to SIS heterodyne receivers that are
cooled using closed-cycle cryocoolers in which the 4 K temperature fluctuations
tend to be the leading cause of IF power fluctuations.


title:
Exciton spectroscopy of hexagonal boron nitride using non-resonant x-ray
  Raman scattering

abstract:
  We report non-resonant x-ray Raman scattering (XRS) measurements from
hexagonal boron nitride for transferred momentum from 2 to 9
$\mathrm{\AA}^{-1}$ along directions both in and out of the basal plane. A
symmetry-based argument, together with real-space full multiple scattering
calculations of the projected density of states in the spherical harmonics
basis, reveals that a strong pre-edge feature is a dominantly $Y_{10}$-type
Frenkel exciton with no other \textit{s}-, \textit{p}-, or \textit{d}-
components. This conclusion is supported by a second, independent calculation
of the \textbf{q}-dependent XRS cross-section based on the Bethe-Salpeter
equation.


title:
The lowest modes around Gaussian solutions of tensor models and the
  general relativity

abstract:
  In the previous paper, the number distribution of the low-lying spectra
around Gaussian solutions representing various dimensional fuzzy tori of a
tensor model was numerically shown to be in accordance with the general
relativity on tori. In this paper, I perform more detailed numerical analysis
of the properties of the modes for two-dimensional fuzzy tori, and obtain
conclusive evidences for the agreement. Under a proposed correspondence between
the rank-three tensor in tensor models and the metric tensor in the general
relativity, conclusive agreement is obtained between the profiles of the
low-lying modes in a tensor model and the metric modes transverse to the
general coordinate transformation. Moreover, the low-lying modes are shown to
be well on a massless trajectory with quartic momentum dependence in the tensor
model. This is in agreement with that the lowest momentum dependence of metric
fluctuations in the general relativity will come from the R^2-term, since the
R-term is topological in two dimensions. These evidences support the idea that
the low-lying low-momentum dynamics around the Gaussian solutions of tensor
models is described by the general relativity. I also propose a renormalization
procedure for tensor models. A classical application of the procedure makes the
patterns of the low-lying spectra drastically clearer, and suggests also the
existence of massive trajectories.


title:
Toroidalization of generating sequences in dimension two function fields
  of positive characteristic

abstract:
  We give a characteristic free proof of the main result of our previous paper
(math.AC/0509697) concerning toroidalization of generating sequences of
valuations in dimension two function fields. We show that when an extension of
two dimensional algebraic regular local rings $R\subset S$ satisfies the
conclusions of the Strong Monomialization theorem of Cutkosky and Piltant, the
map between generating sequences in $R$ and $S$ has a toroidal structure.


title: Theoretical progress on V_us on lattice

abstract:
  Recent lattice studies on (semi-)leptonic kaon decays towards a precise
determination of V_us are reviewed. Attention is given to recent unquenched
calculations and consistency of their results with chiral perturbation theory.


title: Inevitability of Plate Tectonics on Super-Earths

abstract:
  The recent discovery of super-Earths (masses less or equal to 10
earth-masses) has initiated a discussion about conditions for habitable worlds.
Among these is the mode of convection, which influences a planet's thermal
evolution and surface conditions. On Earth, plate tectonics has been proposed
as a necessary condition for life. Here we show, that super-Earths will also
have plate tectonics. We demonstrate that as planetary mass increases, the
shear stress available to overcome resistance to plate motion increases while
the plate thickness decreases, thereby enhancing plate weakness. These effects
contribute favorably to the subduction of the lithosphere, an essential
component of plate tectonics. Moreover, uncertainties in achieving plate
tectonics in the one earth-mass regime disappear as mass increases:
super-Earths, even if dry, will exhibit plate tectonic behaviour.


title:
Directional-dependent thermally activated motion of vortex bundles and
  theory of anomalous Hall effect in type-II conventional and high-Tc
  superconductors

abstract:
  The anomalous Hall effect for type-II conventional and high-Tc
superconductors is studied based upon the theory of thermally activated motion
of vortex bundles jumping over the directional-dependent energy barrier. It is
shown that the Hall anomaly is universal for type-II conventional and high-Tc
superconductors as well as for superconducting bulk materials and thin films,
provided certain conditions are satisfied. We find that the
directional-dependent potential barrier of the vortex bundles renormalizes the
Hall and longitudinal resistivities, and Hall anomaly for superconductors is
induced by the competition between the Magnus force and the random collective
pinning force of the vortex bundle. We also find that the domain of anomalous
Hall effect includes two regions: the region of thermally activated motion of
the small vortex bundles and that of the large vortex bundles separated by the
contour of the quasiorder-disorder first-order phase transition, or the peak
effect of the vortex system. The Hall and longitudinal resistivities as
functions of temperature as well as applied magnetic field have been calculated
for type-II superconducting films and bulk materials. The conditions for
occurring the double sign reversal or reentry phenomenon is also investigated.
All the results are in agreement with the experiments.


title: The First Lunar Ranging Constraints on Gravity Sector SME Parameters

abstract:
  We present the first constraints on pure-gravity sector Standard-Model
Extension (SME) parameters using Lunar Laser Ranging (LLR). LLR measures the
round trip travel time of light between the Earth and the Moon. With 34+ years
of LLR data, we have constrained six independent linear combinations of SME
parameters at the level of $10^{-6}$ to $10^{-11}$. There is no evidence for
Lorentz violation in the LLR dataset.


title:
Testing for Lorentz Violation: Constraints on Standard-Model Extension
  Parameters via Lunar Laser Ranging

abstract:
  We present constraints on violations of Lorentz Invariance based on Lunar
Laser Ranging (LLR) data. LLR measures the Earth-Moon separation by timing the
round-trip travel of light between the two bodies, and is currently accurate to
a few centimeters (parts in $10^{11}$ of the total distance). By analyzing
archival LLR data under the Standard-Model Extension (SME) framework, we
derived six observational constraints on dimensionless SME parameters that
describe potential Lorentz-violation. We found no evidence for Lorentz
violation at the $10^{-6}$ to $10^{-11}$ level in these parameters.


title: pQCD vs. AdS/CFT Tested by Heavy Quark Energy Loss

abstract:
  We predict the charm and bottom quark nuclear modification factors using
weakly coupled pQCD and strongly coupled AdS/CFT drag methods. The
log(pT/M_Q)/pT dependence of pQCD loss and the momentum independence of drag
loss lead to different momentum dependencies for the R_{AA} predictions. This
difference is enhanced by examining a new experimental observable, the double
ratio of charm to bottom nuclear modification factors,
R^{cb}=R^c_{AA}/R^b_{AA}. At LHC the weakly coupled theory predicts R^{cb} goes
to 1; whereas the strongly coupled theory predicts R^{cb} .2 independent of pT.
At RHIC the differences are less dramatic, as the production spectra are
harder, but the drag formula is applicable to higher momenta, due to the lower
temperature.


title: Triage of the Sign Problem

abstract:
  We discuss the sign problem in QCD at nonzero chemical potential and its
relation with chiral symmetry breaking and the spectrum of the Dirac operator
using the framework of chiral random matrix theory. We show that the
Banks-Casher formula is not valid for theories with a sign problem and has to
be replaced by an alternative mechanism that is worked out in detail for QCD in
one dimension at nonzero chemical potential.


title: Hopf Algebras and Congruence Subgroups

abstract:
  We prove that the kernel of the natural action of the modular group on the
center of the Drinfel'd double of a semisimple Hopf algebra is a congruence
subgroup. To do this, we introduce a class of generalized Frobenius-Schur
indicators and endow it with an action of the modular group that is compatible
with the original one.

categories: math.RA hep-th math-ph math.MP math.QA math.RT


title: Area-Preserving Surface Dynamics and S. Saito's Fixed Point Formula

abstract:
  We show that S. Saito's fixed point formula serves as a powerful tool for
counting the number of isolated periodic points of an area-preserving surface
map admitting periodic curves. His notion of periodic curves of types I and II
plays a central role in our discussion. We establish a Shub-Sullivan type
result on the stability of local indices under iterations of the map, the
finiteness of the number of periodic curves of type II, and the absence of
periodic curves of type I. Combined with these results, Saito's formula implies
the existence of infinitely many isolated periodic points whose cardinality
grows exponentially as period tends to infinity.


title: New branch of Kaluza-Klein compactification

abstract:
  We found a new branch of solutions in Freund-Rubin type flux
compactifications. The geometry of these solutions is described as the external
space which has a de Sitter symmetry and the internal space which is
topologically spherical. However, it is not a simple form of dS_p x S^q but a
warped product of de Sitter space and a deformed sphere. We explicitly
constructed numerical solutions for a specific case with p=4 and q=4. We show
that the new branch of solutions emanates from the marginally stable solution
in the branch of dS_4 x S^4 solutions.


title: A characterization of all equilateral triangles in \Bbb Z^3

abstract:
  This paper is a continuation of previous work of the authors. We extend one
of the theorems that gave a way to construct equilateral triangles whose
vertices have integer coordinates to the general situation. An approximate
extrapolation formula for the sequence ET(n) of all equilateral triangles with
vertices in $\{0,1,2,...,n\}^3$ (A 102698) is given and the asymptotic behavior
of this sequence is analyzed.


title: Superstring vertex operators in type IIB matrix model

abstract:
  We clarify the relation between the vertex operators in type IIB matrix model
and superstring. Green-Schwarz light-cone closed superstring theory is obtained
from IIB matrix model on two dimensional noncommutative backgrounds.
Superstring vertex operators should be reproduced from those of IIB matrix
model through this connection. Indeed, we confirm that supergravity vertex
operators in IIB matrix model on the two dimensional backgrounds reduce to
those in superstring theory. Noncommutativity plays an important role in our
identification. Through this correspondence, we can reproduce superstring
scattering amplitudes from IIB matrix model.


title:
Non-perturbative renormalization of four-quark operators and B_K with
  Schroedinger functional scheme in quenched domain-wall QCD

abstract:
  We present non-perturbative renormalization factors for $\Delta S=2$
four-quark operators in quenched domain-wall QCD using the Schroedinger
functional method. Non-perturbative renormalization factor for $B_K$ is
evaluated at hadronic scale. Combined with the non-perturbative RG running
obtained by the Alpha collaboration, our result yields renormalization factor
which converts lattice bare $B_K$ to the renormalization group invariant one.
We apply the renormalization factor to bare $B_K$ previously obtained by the
CP-PACS collaboration with the quenched domain-wall QCD(DWQCD). We compare our
result with previous ones obtained by perturbative renormalization factors,
different renormalization schemes or different quark actions. We also show that
chiral symmetry breaking effects in the renormalization factor are numerically
small.


title: Canes Venatici I cloud of galaxies seen in the H-alpha line

abstract:
  We present results of H-alpha imaging for 42 galaxies in the nearby
low-density cloud Canes Venatici I populated mainly by late-type objects.
Estimates of the H-alpha flux and integrated star formation rate (SFR) are now
available for all 78 known members of this scattered system, spanning a large
range in luminosity, surface brightness, HI content and SFR. Distributions of
the CVnI galaxies versus their SFR, blue absolute magnitude and total hydrogen
mass are given in comparison with those for a population of the nearby
virialized group around M81. We found no essential correlation between star
formation activity in a galaxy and its density environment. A bulk of CVnI
galaxies had enough time to generate their baryon mass with the observed SFR.
Most of them possess also a supply of gas sufficient to maintain their observed
SFR's during the next Hubble time.


title:
Molecular Evolution and Star Formation: From Prestellar Cores to
  Protostellar Cores

abstract:
  We investigate molecular evolution in a star-forming core that is initially a
hydrostatic starless core and collapses to form a low-mass protostar. The
results of a one-dimensional radiation-hydrodynamics calculation are adopted as
a physical model of the core. We first derive radii at which CO and large
organic species sublimate. CO sublimation in the central region starts shortly
before the formation of the first hydrostatic core. When the protostar is born,
the CO sublimation radius extends to 100 AU, and the region inside $\lesssim
10$ AU is hotter than 100 K, at which some large organic species evaporate. We
calculate the temporal variation of physical parameters in infalling shells, in
which the molecular evolution is solved using an updated gas-grain chemical
model to derive the spatial distribution of molecules in a protostellar core.
The shells pass through the warm region of $10 -100$ K in several $\times$
$10^4$ yr, and fall into the central star $\sim 100$ yr after they enter the
region where $T \gtrsim 100$ K. We find that large organic species are formed
mainly via grain-surface reactions at temperatures of $20 -40$ K and then
desorbed into the gas-phase at their sublimation temperatures. Carbon-chain
species can be formed by a combination of gas-phase reactions and grain-surface
reactions following the sublimation of CH$_4$. Our model also predicts that
CO$_2$ is more abundant in isolated cores, while gas-phase large organic
species are more abundant in cores embedded in ambient clouds.


title: Corrections to the running of gauge couplings due to quantum gravity

abstract:
  Concerning the gravitational corrections to the running of gauge couplings
two different results were reported. Some authors claim that gravitational
correction at the one-loop level indicates an interesting effect of universal
gravitational decreasing of gauge couplings, that is, gravitational correction
works universally in the direction of asymptotic freedom no matter how the
gauge coupling behaves without gravity, while others reject the presence of
gravitational correction at the one-loop level at all. Being these calculations
done in the framework of an effective field theory approach to general
relativity, we wanted to draw attention to a recently discovered profound
quantum-gravitational effect of space-time dimension running that inevitably
affects the running of gauge couplings. The running of space-time dimension
indicating gradual reduction of dimension as one gets into smaller scales acts
on the coupling constants in the direction of asymptotic freedom and therefore
in any case manifests the plausibility of this quantum-gravitational effect.
Curiously enough, the results are also in perfect quantitative agreement with
those of Robinson and Wilczek.


title: Light-front quark model analysis of heavy meson radiative decays

abstract:
  We present the magnetic dipole($M1$) transitions $V\to P\gamma$ of various
heavy-flavored mesons such as $(D,D^*,D_s,D^{*}_s,\eta_c, J/\psi)$ and
$(B,B^*,B_s,B^*_s,\eta_b,\Upsilon)$ using the light-front quark model
constrained by the variational principle for the QCD-motivated effective
Hamiltonian. The weak decay constants of heavy mesons and the decay widths for
$V\to P\gamma$ are calculated. The radiative decay for
$\Upsilon\to\eta_{b}\gamma$ process is found to be very helpful to determine
the unmeasured mass of $\eta_b$. Our numerical results are overall in good
agreement with the available experimental data as well as other theoretical
model calculations.


title:
Effect of Ti4+ substitution on structural, transport and magnetic
  properties of La0.67Sr0.33Mn1-xTixO3

abstract:
  La$_{0.67}$Sr$_{0.33}$Mn$_{1-x}$Ti$_x$O$_{3}$ ($0 \le x \le 0.20$)
polycrystalline materials are prepared by employing lower annealing temperature
compared to the temperatures reported for the materials of the same
composition. The transport and magnetic properties of these materials are
significantly different from those compounds prepared at higher annealing
temperature. Samples with $x < 0.10$, show metal-insulator transition and those
with $x \ge 0.10$ exhibit insulating behavior over the entire temperature range
investigated. A gradual transition occurs from ferromagnetic-metallic state to
ferromagnetic-insulator state with increasing Ti substitution. Lattice
parameters and bond lengths of Mn and its near neighbours however do not change
appreciably with the dopant content $x$ in these materials. It is shown that
Ti$^{4+}$ doping in the low temperature annealed samples is inhomogeneous
resulting in isolated Mn rich regions that are connected by a variable range
hopping polaron.


title:
The Boltzmann-Grad limit of the periodic Lorentz gas in two space
  dimensions

abstract:
  The periodic Lorentz gas is the dynamical system corresponding to the free
motion of a point particle in a periodic system of fixed spherical obstacles of
radius $r$ centered at the integer points, assuming all collisions of the
particle with the obstacles to be elastic. In this Note, we study this motion
on time intervals of order $1/r$ and in the limit as $r\to 0^+$, in the case of
two space dimensions.


title:
Ultrafast coelectrophoretic fluorescent staining of proteins with
  carbocyanines

abstract:
  Protein detection on SDS gels or on 2-D gels must combine several features,
such as sensitivity, homogeneity from one protein to another, speed, low cost,
and user-friendliness. For some applications, it is also interesting to have a
nonfixing stain, so that proteins can be mobilized from the gel for further use
(electroelution, blotting). We show here that coelectrophoretic staining by
fluorophores of the oxacarbocyanine family, and especially
diheptyloxacarbocyanine, offers several positive features. The sensitivity is
intermediate between the one of colloidal CBB and the one of fluroescent
ruthenium complexes. Detection is achieved within 1 h after the end of the
electrophoretic process and does not use any fixing or toxic agent. The
fluorescent SDS-carbocyanine-protein complexes can be detected either with a
laser scanner with an excitation wavelength of 488 nm or with a UV table
operating at 302 nm. Excellent sequence coverage in subsequent MS analysis of
proteolytic peptides is also achieved with this detection method.


title: Exchange-energy functionals for finite two-dimensional systems

abstract:
  Implicit and explicit density functionals for the exchange energy in finite
two-dimensional systems are developed following the approach of Becke and
Roussel [Phys. Rev. A 39, 3761 (1989)]. Excellent agreement for the
exchange-hole potentials and exchange energies is found when compared with the
exact-exchange reference data for the two-dimensional uniform electron gas and
few-electron quantum dots, respectively. Thereby, this work significantly
improves the availability of approximate density functionals for dealing with
electrons in quasi-two-dimensional structures, which have various applications
in semiconductor nanotechnology.


title:
Nuclear Structure Relevant to Neutrinoless Double Beta Decay: 76Ge and
  76Se

abstract:
  The possibility of observing neutrinoless double beta decay offers the
opportunity of determining the neutrino mass IF the nuclear matrix element were
known. Theoretical calculations are uncertain and measurements of the
occupations of valence orbits by nucleons active in the decay can be important.
The occupation of valence neutron orbits in the ground states of 76Ge and 76Se
were determined by precisely measuring cross sections for both neutron-adding
and removing transfer reactions. Our results indicate that the Fermi surface is
much more diffuse than in theoretical (QRPA) calculations. We find that the
populations of at least three orbits change significantly between these two
ground states while in the calculations the changes are confined primarily to
one orbit.


title:
The tensor of interaction of a two-level system with an arbitrary strain
  field

abstract:
  The interaction between two-level systems (TLS) and strain fields in a solid
is contained in the diagonal matrix element of the interaction hamiltonian,
$\delta$, which, in general, has the expression $\delta=2[\gamma]:[S]$, with
the tensor $[\gamma]$ describing the TLS ``deformability'' and $[S]$ being the
symmetric strain tensor. We construct $[\gamma]$ on very general grounds, by
associating to the TLS two objects: a direction, $\hat\bt$, and a forth rank
tensor of coupling constants, $[[R]]$. Based on the method of construction and
on the invariance of the expression of $\delta$ with respect to the symmetry
transformation of the solid, we conclude that $[[R]]$ has the same structure as
the tensor of stiffness constants, $[[c]]$, from elasticity theory. In
particular, if the solid is isotropic, $[[R]]$ has only two independent
parameters, which are the equivalent of the Lam\'e constants. Employing this
model we calculate the absorption and emission rates of phonons on TLSs and
show that in isotropic solids, on average, the longitudinal phonons interact
stronger with the TLSs than the transversal ones, as it is observed in
experiments. We also show that in isotropic solids, a transversal wave leaves
unperturbed all the TLSs with the direction contained in one of the two planes
that are perpendicular either to the wave propagation direction or to the
polarization direction and that a longitudinal strain applied to the solid
polarises the TLS ensemble.


title: Noncommutative families of instantons

abstract:
  We construct $\theta$-deformations of the classical groups SL(2,H) and Sp(2).
Coacting on the basic instanton on a noncommutative four-sphere $S^4_\theta$,
we construct a noncommutative family of instantons of charge 1. The family is
parametrized by the quantum quotient of $SL_\theta(2,H)$ by $Sp_\theta(2)$.


title: Boost symmetry in the Quantum Gravity sector

abstract:
  We perform a canonical quantization of gravity in a second-order formulation,
taking as configuration variables those describing a 4-bein, not adapted to the
space-time splitting. We outline how, neither if we fix the Lorentz frame
before quantizing, nor if we perform no gauge fixing at all, is invariance
under boost transformations affected by the quantization.


title: Uncertainty Relation for the Discrete Fourier Transform

abstract:
  We derive an uncertainty relation for two unitary operators which obey a
commutation relation of the form UV=exp[i phi] VU. Its most important
application is to constrain how much a quantum state can be localised
simultaneously in two mutually unbiased bases related by a Discrete Fourier
Transform. It provides an uncertainty relation which smoothly interpolates
between the well known cases of the Pauli operators in 2 dimensions and the
continuous variables position and momentum. This work also provides an
uncertainty relation for modular variables, and could find applications in
signal processing. In the finite dimensional case the minimum uncertainty
states, discrete analogues of coherent and squeezed states, are minimum energy
solutions of Harper's equation, a discrete version of the Harmonic oscillator
equation.


title: The thermodynamic limit for fractional exclusion statistics

abstract:
  I discuss Haldane's concept of generalised exclusion statistics (Phys. Rev.
Lett. {\bf 67}, 937, 1991) and I show that it leads to inconsistencies in the
calculation of the particle distribution that maximizes the partition function.
These inconsistencies appear when mutual exclusion statistics is manifested
between different subspecies of particles in the system. In order to eliminate
these inconsistencies, I introduce new mutual exclusion statistics parameters,
which are proportional to the dimension of the Hilbert sub-space on which they
act. These new definitions lead to properly defined particle distributions and
thermodynamic properties. In another paper (arXiv:0710.0728) I show that
fractional exclusion statistics manifested in general systems with interaction
have these, physically consistent, statistics parameters.


title:
Near-Constant Mean Curvature Solutions of the Einstein Constraint
  Equations with Non-Negative Yamabe Metrics

abstract:
  We show that sets of conformal data on closed manifolds with the metric in
the positive or zero Yamabe class, and with the gradient of the mean curvature
function sufficiently small, are mapped to solutions of the Einstein constraint
equations. This result extends previous work which required the conformal
metric to be in the negative Yamabe class, and required the mean curvature
function to be nonzero.


title:
Distinguishing SUSY scenarios using \tau polarisation and \tilde\chi^0_1
  Dark Matter

abstract:
  We discuss first a method of measuring $\tau$ polarisation at the ILC using
the 1--prong hadronic decays of the $\tau$. We then show in this contribution
how a study of the $\tilde \tau$ sector and particularly use of decay $\tau$
polarisation can offer a very good handle for distinguishing between mSUGRA and
a SUSY-GUT scenario, both of which can give rise to appropriate Dark Matter.


title: The afterglow onset for GRB060418 and GRB060607A

abstract:
  Gamma-ray burst are thought to be produced by highly relativistic outflows.
Although upper and lower limits for the outflow initial Lorentz factor
$\Gamma_0$ are available, observational efforts to derive a direct
determination of $\Gamma_0$ have so far failed or provided ambiguous results.
As a matter of fact, the shape of the early-time afterglow light curve is
strongly sensitive on $\Gamma_0$ which determines the time of the afterglow
peak, i.e. when the outflow and the shocked circumburst material share a
comparable amount of energy. We now comment early-time observations of the
near-infrared afterglows of GRB 060418 and GRB 060607A performed by the REM
robotic telescope. For both events, the afterglow peak was singled out and
allowed us to determine the initial fireball Lorentz, $\Gamma_0\sim 400$.


title: Fractional exclusion statistics in general systems with interaction

abstract:
  I show that fractional exclusion statistics (FES) is manifested in general
interacting systems and I calculate the exclusion statistics parameters. Most
importantly, I show that the mutual exclusion statistics parameters--when the
presence of particles in one Hilbert space influences the dimension of another
Hilbert space--are proportional to the dimension of the Hilbert space on which
they act. This result, although surprising and different from the usual way of
understanding the FES, renders this statistics consistent and valid in the
thermodynamic limit, in accordance with the conjucture introduced in J. Phys.
A: Math. Theor. 40, F1013 (2007).


title: Semileptonic decays of heavy-light pseudoscalar mesons

abstract:
  I discuss the results of a recent quenched lattice calculation of the two
independent form factors parametrizing the semileptonic decays between
heavy-light pseudoscalar mesons. The differential decay rate of the process B
--> D l nu has been calculated at non vanishing momentum transfer both in the
case of the light leptons, l=e,mu, and in the case of a non vanishing lepton
mass, l=tau.


title: Fractional Charge and Quantized Current in the Quantum Spin Hall State

abstract:
  A profound manifestation of topologically non-trivial states of matter is the
occurrence of fractionally charged elementary excitations. The quantum spin
Hall insulator state is a fundamentally novel quantum state of matter that
exists at zero external magnetic field. In this work, we show that a magnetic
domain wall at the edge of the quantum spin Hall insulator carries one half of
the unit of electron charge, and we propose an experiment to directly measure
this fractional charge on an individual basis. We also show that as an
additional consequence, a rotating magnetic field can induce a quantized dc
electric current, and vice versa.


title: Symplectic resolutions, Lefschetz property and formality

abstract:
  We introduce a method to resolve a symplectic orbifold into a smooth
symplectic manifold. Then we study how the formality and the Lefschetz property
of the symplectic resolution are compared with that of the symplectic orbifold.
We also study the formality of the symplectic blow-up of a symplectic orbifold
along symplectic submanifolds disjoint from the orbifold singularities. This
allows us to construct the first example of a simply connected compact
symplectic manifold of dimension 8 which satisfies the Lefschetz property but
is not formal, therefore giving a counter-example to a conjecture of Babenko
and Taimanov.


title:
Comment on ``Coherent Control of a V-Type Three-Level System in a Single
  Quantum Dot''

abstract: This is a Comment on Phys. Rev. Lett., {\bf 95}, 187404 (2005)


title:
Total control over ultracold interactions via electric and magnetic
  fields

abstract:
  The scattering length is commonly used to characterize the strength of
ultracold atomic interactions, since it is the leading parameter in the
low-energy expansion of the scattering phase shift. Its value can be modified
via a magnetic field, by using a Feshbach resonance. However, the effective
range term, which is the second parameter in the phase shift expansion,
determines the width of the resonance and gives rise to important properties of
ultracold gases. Independent control over this parameter is not possible by
using a magnetic field only. We demonstrate that a combination of magnetic and
electric fields can be used to get independent control over both parameters,
which leads to full control over elastic ultracold interactions.


title: Obstruction theory on 8-manifolds

abstract:
  This note gives a uniform, self-contained, and fairly direct approach to a
variety of obstruction-theoretic problems on 8-manifolds. We give necessary and
sufficient cohomological critera for the existence of almost complex and almost
quaternionic structures on the tangent bundle and for the reduction of the
structure group to U(3) by the homomorphism U(3) --> O(8) given by the Lie
algebra representation of PU(3).


title:
Critical points of quadratic renormalizations of random variables and
  phase transitions of disordered polymer models on diamond lattices

abstract:
  We study the wetting transition and the directed polymer delocalization
transition on diamond hierarchical lattices.These two phase transitions with
frozen disorder correspond to the critical points of quadratic renormalizations
of the partition function.(These exact renormalizations on diamond lattices can
also be considered as approximate Migdal-Kadanoff renormalizations for
hypercubic lattices). In terms of the rescaled partition function
$z=Z/Z_{typ}$,we find that the critical point corresponds to a fixed point
distribution with a power-law tail $P_c(z) \sim \Phi(\ln z)/z^{1+\mu}$ as $z
\to +\infty$ (up to some sub-leading logarithmic correction $\Phi(\ln z)$), so
that all moments $z^{n}$ with $n>\mu$ diverge. For the wetting transition, the
first moment diverges $\bar{z}=+\infty$ (case $0<\mu<1$), and the critical
temperature is strictly below the annealed temperature $T_c<T_{ann}$. For the
directed polymer case, the second moment diverges $\bar{z^2}=+\infty$ (case
$1<\mu<2$), and the critical temperature is strictly below the exactly known
transition temperature $T_2$ of the second moment.We then consider the
correlation length exponent $\nu$ :the linearized renormalization around the
fixed point distribution coincides with the transfer matrix describing a
directed polymer on the Cayley tree, but the random weights determined by the
fixed point distribution $P_c(z)$ are broadly distributed. This induces some
changes in the travelling wave solutions with respect to the usual case of more
narrow distributions.


title:
Colour image segmentation by the vector-valued Allen-Cahn phase-field
  model: a multigrid solution

abstract:
  We propose a new method for the numerical solution of a PDE-driven model for
colour image segmentation and give numerical examples of the results. The
method combines the vector-valued Allen-Cahn phase field equation with initial
data fitting terms. This method is known to be closely related to the
Mumford-Shah problem and the level set segmentation by Chan and Vese. Our
numerical solution is performed using a multigrid splitting of a finite element
space, thereby producing an efficient and robust method for the segmentation of
large images.


title: Dynamical Simulations with Highly Improved Staggered Quarks

abstract:
  It is well established that lattice artifacts can be suppressed substantially
by the use of SU(3)-projected smeared links in the fermion action. An example
is the Highly Improved Staggered Quark action where the ASQ-like effective
links are constructed from reunitarized Fat7 links. A general procedure is
presented for computing the derivative of the fermion action with respect to
the base links (fermion force) - a key component in dynamical simulations using
molecular dynamics evolution. The method is iterative and can be applied to
actions with arbitrary levels of smearing and reunitarization. The cost of
calculating the fermion force is determined for the ASQ action and the HISQ
action. Test results show that calculating the HISQ force is about two times
more expensive than the ASQ force.


title: Superconductivity in novel Ge-based skutterudites: {Sr,Ba}Pt_4Ge_{12}

abstract:
  Combining experiments and ab initio models we report on $\rm SrPt_4Ge_{12}$
and $\rm BaPt_4Ge_{12}$ as members of a novel class of superconducting
skutterudites, where Sr or Ba atoms stabilize a framework entirely formed by
Ge-atoms. Below $T_c=5.35$ K, and 5.10 K for $\rm BaPt_4Ge_{12}$ and $\rm
SrPt_4Ge_{12}$, respectively, electron-phonon coupled superconductivity
emerges, ascribed to intrinsic features of the Pt-Ge framework, where Ge-$p$
states dominate the electronic structure at the Fermi energy.


title: Transport and spectral functions in high-temperature QCD

abstract:
  The current status of transport coefficients in relativistic field theories
at high temperature is reviewed. I contrast weak coupling results obtained
using kinetic theory/diagrammatic techniques with strong coupling results
obtained using gauge/gravity duality, and describe the recent developments in
extracting transport coefficients and spectral functions from lattice QCD
simulations. The fate of quarkonium at high temperature as seen from the
lattice is briefly mentioned as well.


title: On 3-dimensional Asymptotically Harmonic Manifolds

abstract:
  Let (M,g) be a complete, simply connected Riemannian manifold of dimension 3
without conjugate points. We show that M is a hyperbolic manifold of constant
sectional curvature, provided M is asymptotically harmonic of constant h > 0.


title: B Semileptonic Decays at High Recoil Momentum

abstract:
  We explore the possibility of studying $B\to\pi l\nu$ semileptonic decays at
large recoil momentum. Our methods include the use of a random-wall source for
the pion to reduce statistical errors, and different smearing functions are
used for the B meson to improve the overlap with the ground state. We observe,
in general, a factor of 3-4 improvement in the signal-to-noise ratio in
correlation functions if random-wall propagators are used.


title:
Principle of Minimum Distance in Space of States as New Principle in
  Quantum Physics

abstract:
  The mathematician Leonhard Euler (1707-1783) appears to have been a
philosophical optimist having written: "Since the fabric of universe is the
most perfect and is the work of the most wise Creator, nothing whatsoever take
place in this universe in which some relation of maximum or minimum does not
appear. Wherefore, there is absolutely no doubt that every effect in universe
can be explained as satisfactory from final causes themselves the aid of the
method of Maxima and Minima, as can from the effective causes". Having in mind
this kind of optimism, in the papers [1-16] we introduced and investigated the
possibility to construct a predictive analytic theory of the elementary
particle interaction based on the principle of minimum distance in the space of
quantum states (PMD-SQS). So, choosing the partial transition amplitudes as the
system variational variables and the distance in the space of the quantum
states as a measure of the system effectiveness, we obtained the results
[1-16]. These results proved that the principle of minimum distance in space of
quantum states (PMD-SQS) can be chosen as variational principle by which we can
find the analytic expressions of the partial transition amplitudes. In this
paper we present a description of hadron-hadron scattering via principle of
minimum distance PMD-SQS when the distance in space of states is minimized with
two directional constraints. Then by using the available experimental
(pion-nucleon and kaon-nucleon) phase shifts we obtained not only consistent
experimental tests of the PMD-SQS optimality, but also strong experimental
evidences for new principles in hadronic physics such as: Principle of
nonextensivity conjugation via the Riesz-Thorin relation (1/2p+1/2q=1) and a
new Principle of limited uncertainty in nonextensive quantum physics.


title: Generalized Super-Cerenkov Radiations in Nuclear and Hadronic Media

abstract:
  Generalized Super-Cerenkov Radiations (SCR), as well as their SCR-signatures
are investigated and classified. Two general SCR- coherence conditions are
found as two natural extremes of the same spontaneous particles decay in
(dielectric, nuclear or hadronic) media The main results on the quantum theory
of the SCR-phenomena as well as the results of the first experimental test of
the super-coherence conditions, obtained by using the experimental data from
BNL are presented. The new concepts such as: SCR-gluons, SCR-W-bosons and
SCR-Z-bosons, all three suggested by elementary particle classification, are
introduced. The gluonic Super-Cerenkov-like radiation, first introduced here,
is schematically described. The interpretation of some recent RHIC results as
signature of the SCR-gluons is suggested.


title: New Nuclear And Subnuclear Exotic Decays

abstract:
  In this paper new nuclear and subnuclear exotic decays are investigated. Some
theoretical problems of the pionic radioactivity, such as fission-like models,
applicable to all kind of exotic nuclear and subnuclear decays are presented.
The induced nuclear and subnuclear decays are discussed. Moreover, using the
recent results on the spontaneous fission half lives T of the heavy nuclei with
Z new predictions on the pionic yields in the region of superheavy elements are
presented.


title:
Mixing Kohonen Algorithm, Markov Switching Model and Detection of
  Multiple Change-Points: An Application to Monetary History

abstract:
  The present paper aims at locating the breakings of the integration process
of an international system observed during about 50 years in the 19th century.
A historical study could link them to special events, which operated as
exogenous shocks on this process. The indicator of integration used is the
spread between the highest and the lowest among the London, Hamburg and Paris
gold-silver prices. Three algorithms are combined to study this integration: a
periodization obtained with the SOM algorithm is confronted to the estimation
of a two-regime Markov switching model, in order to give an interpretation of
the changes of regime; in the same time change-points are identified over the
whole period providing a more precise interpretation of the various types of
regulation.


title:
Universality and Scaling at the chiral transition in two-flavor QCD at
  finite temperature

abstract:
  The order of the phase transition in finite-temperature QCD with two
degenerate light quarks is still an open problem and corresponds to the last
question mark in the zero-density phase diagram of QCD. We argue that
establishing the nature of the transition in this case is also a crucial test
for numerical simulations of lattice QCD, allowing precise estimates of
possible systematic errors related e.g. to the choice of fermion-simulation
algorithm or of discretized formulation for fermions.


title: Calibration of the mirror system in the HERA-B RICH

abstract:
  The mirror system of the HERA-B RICH consists of two spherical and two planar
mirrors, composed of altogether 116 mirror segments. Analysis of displacements
of the \v{C}erenkov ring center relative to the charged particle track, for
given spherical-planar segment pairs, leads to accurate information regarding
the orientation of individual mirror segments. The method is described and the
effect of applying the required corrections on the \v{C}erenkov angle
resolution of the HERA-B RICH is discussed.


title:
A Fast Heuristic Algorithm Based on Verification and Elimination Methods
  for Maximum Clique Problem

abstract:
  A clique in an undirected graph G= (V, E) is a subset V' V of vertices, each
pair of which is connected by an edge in E. The clique problem is an
optimization problem of finding a clique of maximum size in graph. The clique
problem is NP-Complete. We have succeeded in developing a fast algorithm for
maximum clique problem by employing the method of verification and elimination.
For a graph of size N there are 2N sub graphs, which may be cliques and hence
verifying all of them, will take a long time. Idea is to eliminate a major
number of sub graphs, which cannot be cliques and verifying only the remaining
sub graphs. This heuristic algorithm runs in polynomial time and executes
successfully for several examples when applied to random graphs and DIMACS
benchmark graphs.


title: Observations of V838 Mon in the CO rotational lines

abstract:
  We investigate the structure of a field around the position of V838 Mon as
seen in the lowest CO rotational transitions. We also measure and analyse
emission in the same lines at the position of V838 Mon.Observations have
primarily been done in the CO J = 2-1 and J = 3-2 lines using the KOSMA
telescope. A field of 3.4 squared degrees has been mapped in the on-the-fly
mode in these transitions. Longer integration spectra in the on-off mode have
been obtained to study the emission at the position of V838 Mon. Selected
positions in the field have also been observed in the CO J = 1-0 transition
using the Delingha telescope.In the observed field we have identified many
molecular clouds. They can be divided into two groups from the point of view of
their observed radial velocities. One, having V(LSR) in the range 18-32 km/s,
can be identified with the Perseus Galactic arm. The other one, having V(LSR)
between 44-57 km/s, probably belongs to the Norma-Cygnus arm. The radial
velocity of V838 Mon is within the second range but the object does not seem to
be related to any of the observed clouds. We did not find any molecular buble
of a 1 degree dimension around the position of V838 Mon claimed in van Loon et
al. An emission has been detected at the position of the object in the CO J =
2-1 and J = 3-2 transitions. The emission is very narrow (FWHM ~ 1.2 km/s) and
at V(LSR) = 53.3 km/s. Our analysis of the data suggests that the emission is
probably extended.


title:
Nuclear Tuning and Detuning of the Electron Spin Resonance in a Quantum
  Dot

abstract:
  We study nuclear spin dynamics in a quantum dot close to the conditions of
electron spin resonance. We show that at small frequency mismatch the nuclear
field detunes the resonance. Remarkably, at larger frequency mismatch its
effect is opposite: The nuclear system is bistable, and in one of the stable
states the field accurately tunes the electron spin splitting to resonance. In
this state the nuclear field fluctuations are strongly suppressed and nuclear
spin relaxation is accelerated.


title: Leptonic secondary emission in a hadronic microquasar model

abstract:
  Context: It has been proposed that the origin of the very high-energy photons
emitted from high-mass X-ray binaries with jet-like features, so-called
microquasars (MQs), is related to hadronic interactions between relativistic
protons in the jet and cold protons of the stellar wind. Leptonic secondary
emission should be calculated in a complete hadronic model that include the
effects of pairs from charged pion decays inside the jets and the emission from
pairs generated by gamma-ray absorption in the photosphere of the system. Aims:
We aim at predicting the broadband spectrum from a general hadronic microquasar
model, taking into account the emission from secondaries created by charged
pion decay inside the jet. Methods: The particle energy distribution for
secondary leptons injected along the jets is consistently derived taking the
energy losses into account. We also compute the spectral energy distribution
resulting from these leptons is calculated after assuming different values of
the magnetic field inside the jets. The spectrum of the gamma-rays produced by
neutral pion-decay and processed by electromagnetic cascades under the stellar
photon field. Results: We show that the secondary emission can dominate the
spectral energy distribution at low energies (~1 MeV). At high energies, the
production spectrum can be significantly distorted by the effect of
electromagnetic cascades. These effects are phase-dependent, and some
variability modulated by the orbital period is predicted.


title: The Einstein-Yang-Mills equations from Bianchi identities

abstract:
  We suggest a novel extension to the Kaluza-Klein scheme that allows us to
obtain consistently all SU(n) Einstein-Yang-Mills theories. This construction
is based on allowing the five-dimensional spacetime to carry some non-vanishing
torsion; however, the four-dimensional spacetime remains intrinsically
torsion-free.


title:
Modelling Bonds & Credit Default Swaps using a Structural Model with
  Contagion

abstract:
  This paper develops a two-dimensional structural framework for valuing credit
default swaps and corporate bonds in the presence of default contagion.
Modelling the values of related firms as correlated geometric Brownian motions
with exponential default barriers, analytical formulae are obtained for both
credit default swap spreads and corporate bond yields. The credit dependence
structure is influenced by both a longer-term correlation structure as well as
by the possibility of default contagion. In this way, the model is able to
generate a diverse range of shapes for the term structure of credit spreads
using realistic values for input parameters.


title: Measuring the Tensor Polarization of Positronium

abstract:
  A method for measuring the tensor polarization in a positronium (Ps) beam is
proposed, which is based on the determination of the Ps lifetime as a function
of the orientation of a homogeneous magnetic field. The dependence of the
orthopositronum (o-Ps) lifetime on the angle between the directions of the
magnetic field and the tensor polarization of the Ps beam can be determined
from the results of measurements from two or more field orientations.


title: Finite-size effects on the dynamics of the zero-range process

abstract:
  We study finite-size effects on the dynamics of a one-dimensional zero-range
process which shows a phase transition from a low-density disordered phase to a
high-density condensed phase. The current fluctuations in the steady state show
striking differences in the two phases. In the disordered phase, the variance
of the integrated current shows damped oscillations in time due to the motion
of fluctuations around the ring as a dissipating kinematic wave. In the
condensed phase, this wave cannot propagate through the condensate, and the
dynamics is dominated by the long-time relocation of the condensate from site
to site.


title: Quark-Gluon Plasma/Black Hole duality from Gauge/Gravity Correspondence

abstract:
  The Quark-Gluon Plasma (QGP) is the QCD phase of matter expected to be formed
at small proper-times in the collision of heavy-ions at high energy.
Experimental observations seem to favor a strongly coupled QCD plasma with the
hydrodynamic properties of a quasi-perfect fluid, i.e. rapid thermalization (or
isotropization) and small viscosity. The theoretical investigation of such
properties is not obvious, due to the the strong coupling. The Gauge/Gravity
correspondence provides a stimulating framework to explore the strong coupling
regime of gauge theories using the dual string description. After a brief
introduction to Gauge/Gravity duality, and among various existing studies, we
focus on challenging problems of QGP hydrodynamics, such as viscosity and
thermalization, in terms of gravitational duals of both the static and
relativistically evolving plasma. We show how a Black Hole geometry arises
naturally from the dual properties of a nearly perfect fluid and explore the
lessons and prospects one may draw for actual heavy ion collisions from the
Gauge/Gravity duality approach.


title:
The Cause of Photospheric and Helioseismic Responses to Solar Flares:
  High-Energy Electrons or Protons?

abstract:
  Analysis of the hydrodynamic and helioseismic effects in the photosphere
during the solar flare of July 23, 2002, observed by Michelson Doppler Imager
(MDI) on SOHO, and high-energy images from RHESSI shows that these effects are
closely associated with sources of the hard X-ray emission, and that there are
no such effects in the centroid region of the flare gamma-ray emission. These
results demonstrate that contrary to expectations the hydrodynamic and
helioseismic responses (''sunquakes") are more likely to be caused by
accelerated electrons than by high-energy protons. A series of multiple
impulses of high-energy electrons forms a hydrodynamic source moving in the
photosphere with a supersonic speed. The moving source plays a critical role in
the formation of the anisotropic wave front of sunquakes.


title: Optical spectroscopy of Cyg X-1

abstract:
  The star HDE 226868 known as an optical counterpart of the black hole
candidate Cyg X-1 has been observed in H_alpha region using spectrograph at
Ondrejov 2-m telescope. The orbital parameters are determined from HeI-line by
means of the author's method of Fourier disentangling. Preliminary results are
also presented of disentangling the H_alpha-line into a P-Cyg profile of the
(optical) primary and an emission profile of the circumstellar matter (and a
telluric component).


title:
Geometrical tests of cosmological models. I. Probing dark energy using
  the kinematics of high-redshift galaxies

abstract:
  We suggest to use the observationally measured and theoretically justified
correlation between size and rotational velocity of galactic discs as a viable
method to select a set of high redshift standard rods which may be used to
explore the dark energy content of the universe via the classical
angular-diameter test. Here we explore a new strategy for an optimal
implementation of this test. We propose to use the rotation speed of high
redshift galaxies as a standard size indicator and show how high resolution
multi-object spectroscopy and ACS/HST high quality spatial images, may be
combined to measure the amplitude of the dark energy density parameter, or to
constrain the cosmic equation of state parameter for a smooth dark energy
component. We evaluate how systematics may affect the proposed tests, and find
that a linear standard rod evolution, causing galaxy dimensions to be up to 30%
smaller at z=1.5, can be uniquely diagnosed, and will minimally bias the
confidence level contours in the [Omega_Q, w] plane. Finally, we show how to
derive, without a priori knowing the specific functional form of disc
evolution, a cosmology-evolution diagram with which it is possible to establish
a mapping between different cosmological models and the amount of galaxy
disc/luminosity evolution expected at a given redshift.


title:
Geometrical tests of cosmological models. II. Calibration of rotational
  widths and disc scaling relations

abstract:
  This series of papers is dedicated to a new technique to select galaxies that
can act as standard rods and standard candles in order to perform geometrical
tests on large samples of high redshift galaxies to constrain different
cosmological parameters. The goals of this paper are (1) to compare different
rotation indicators in order to understand the relation between rotation
velocities extracted from observations of the Halpha line and the [OII]3727
line, and (2) determine the scaling relations between physical size, surface
brightness and magnitude of galaxies and their rotation velocity using the
SFI++, a large catalog of nearby galaxies observed at I-band. A good
correlation is observed between the rotation curve-derived velocities of the
Halpha and [OII] observations, as well as between those calculated from
velocity histograms, justifying the direct comparison of velocities measured
from Halpha rotation curves in nearby galaxies and from [OII] line widths at
higher redshifts. To provide calibration for the geometrical tests, we give
expressions for the different scaling relations between properties of galaxies
(size, surface brightness, magnitude) and their rotation speeds. Apart from the
Tully-Fisher relation, we derive the size-rotation velocity and surface
brightness-rotation velocity relations with unprecedentedly small scatters. We
show how the best size-rotation velocity relation is derived when size is
estimated not from disc scale lengths but from the isophotal diameter r23.5,
once these have been corrected for inclination and extinction effects.


title:
Geometrical tests of cosmological models. III. The cosmology-evolution
  diagram at z=1

abstract:
  The rotational velocity of distant galaxies, when interpreted as a size
(luminosity) indicator, may be used as a tool to select high redshift standard
rods (candles) and probe world models and galaxy evolution via the classical
angular diameter-redshift or Hubble diagram tests. We implement the proposed
testing strategy using a sample of 30 rotators spanning the redshift range
0.2<z<1 with high resolution spectra and images obtained by the VIMOS/VLT Deep
Redshift Survey (VVDS) and the Great Observatories Origins Deep Survey (GOODs).
We show that by applying at the same time the angular diameter-redshift and
Hubble diagrams to the same sample of objects (i.e. velocity selected galactic
discs) one can derive a characteristic chart, the cosmology-evolution diagram,
mapping the relation between global cosmological parameters and local
structural parameters of discs such as size and luminosity. This chart allows
to put constraints on cosmological parameters when general prior information
about discs evolution is available. In particular, by assuming that equally
rotating large discs cannot be less luminous at z=1 than at present (M(z=1) <
M(0)), we find that a flat matter dominated cosmology (Omega_m=1) is excluded
at a confidence level of 2sigma and an open cosmology with low mass density
(Omega_m = 0.3) and no dark energy contribution is excluded at a confidence
level greater than 1 sigma. Inversely, by assuming prior knowledge about the
cosmological model, the cosmology-evolution diagram can be used to gain useful
insights about the redshift evolution of the structural parameters of baryonic
discs hosted in dark matter halos of nearly equal masses.


title: On the seismic age of the Sun

abstract:
  We use low-degree acoustic modes obtained by the BiSON to estimate the
main-sequence age $t_\odot$ of the Sun. The calibration is accomplished by
linearizing the deviations from a standard solar model the seismic frequencies
of which are close to those of the Sun. Formally, we obtain the preliminary
value $t_\odot=4.68\pm0.02 $Gy, coupled with an initial heavy-element abundance
$Z=0.0169\pm0.0005$. The quoted standard errors, which are not independent, are
upper bounds implied under the assumption that the standard errors in the
observed frequencies are independent.


title: Small Scale Energy Cascade of the Solar Wind Turbulence

abstract:
  Magnetic fluctuations in the solar wind are distributed according to
Kolmogorov's power law $f^{-5/3}$ below the ion cyclotron frequency $f_{ci}$.
Above this frequency, the observed steeper power law is usually interpreted in
two different ways: a dissipative range of the solar wind turbulence or another
turbulent cascade, the nature of which is still an open question. Using the
Cluster magnetic data we show that after the spectral break the intermittency
increases toward higher frequencies, indicating the presence of non-linear
interactions inherent to a new inertial range and not to the dissipative range.
At the same time the level of compressible fluctuations raises. We show that
the energy transfer rate and intermittency are sensitive to the level of
compressibility of the magnetic fluctuations within the small scale inertial
range. We conjecture that the time needed to establish this inertial range is
shorter than the eddy-turnover time, and is related to dispersive effects. A
simple phenomenological model, based on the compressible Hall MHD, predicts the
magnetic spectrum $\sim k^{-7/3+2\alpha}$, which depends on the degree of
plasma compression $\alpha$.


title: On the conformal anomaly of k-strings

abstract:
  We discuss the long distance behaviour of the flux tube associated to baryon
vertices and argue that, if the gauge system admits stable k-strings, the
conformal field theory describing this string in the IR has conformal anomaly
c=(d-2)\sigma_k/\sigma, where \sigma_k is the k-string tension and \sigma that
of the fundamental representation. We check this result in a 3D Z_4 gauge model
at finite temperature, where a string effect directly related to "c" can be
clearly identified.


title: Photometric Observations of Supernova 2002hh

abstract:
  CCD VRI photometry is presented for SN 2002hh from 14 days after the outburst
till day 347. SN 2002hh appears to be normal type IIP supernova regarding both
luminosity and the shape of the light curve, which is similar to SN 1999gi.


title: Atomic diffraction in counter-propagating Gaussian pulses of laser light

abstract:
  We present an analysis of atomic diffraction due to the interaction of an
atomic beam with a pair of Gaussian light pulses. We derive a simple analytical
expression for the populations in different diffraction orders. The validity of
the obtained solution extends beyond the Raman-Nath regime, where the kinetic
energy associated with different diffraction peaks is neglected, into the
so-called channeling regime where accurate analytical expressions have not
previously been available for the diffraction. Comparison with experimental
results and exact numerical solutions demonstrate the validity of our
analytical formula.


title:
Towards unravelling the structural distribution of ultra-high-energy
  cosmic ray sources

abstract:
  We investigate the possibility that near future observations of
ultra-high-energy cosmic rays (UHECRs) can unveil their local source
distribution, which reflects the observed local structures if their origins are
astrophysical objects. In order to discuss this possibility, we calculate the
arrival distribution of UHE protons taking into account their propagation
process in intergalactic space i.e. energy losses and deflections by
extragalactic magnetic field (EGMF). For a realistic simulation, we construct
and adopt a model of a structured EGMF and UHECR source distribution, which
reproduce the local structures actually observed around the Milky Way. The
arrival distribution is compared statistically to their source distribution
using correlation coefficient. We specially find that UHECRs above
$10^{19.8}$eV are best indicators to decipher their source distribution within
100 Mpc, and detection of about 500 events on all the sky allows us to unveil
the local structure of UHE universe for plausible EGMF strength and the source
number density. This number of events can be detected by five years observation
by Pierre Auger Observatory.


title: On the stability of periodically time-dependent quantum systems

abstract:
  The main motivation of this article is to derive sufficient conditions for
dynamical stability of periodically driven quantum systems described by a
Hamiltonian H(t), i.e., conditions under which it holds sup_{t in R} |
(psi(t),H(t) psi(t)) |<\infty where psi(t) denotes a trajectory at time t of
the quantum system under consideration. We start from an analysis of the domain
of the quasi-energy operator. Next we show, under certain assumptions, that if
the spectrum of the monodromy operator U(T,0) is pure point then there exists a
dense subspace of initial conditions for which the mean value of energy is
uniformly bounded in the course of time. Further we show that if the propagator
admits a differentiable Floquet decomposition then || H(t) psi(t) || is bounded
in time for any initial condition psi(0), and one employs the quantum KAM
algorithm to prove the existence of this type of decomposition for a fairly
large class of H(t). In addition, we derive bounds uniform in time on
transition probabilities between different energy levels, and we also propose
an extension of this approach to the case of a higher order of
differentiability of the Floquet decomposition. The procedure is demonstrated
on a solvable example of the periodically time-dependent harmonic oscillator.


title:
Four-body continuum-discretized coupled-channels calculations using a
  transformed harmonic oscillator basis

abstract:
  The scattering of a weakly bound three-body system by a target is discussed.
A transformed harmonic oscillator basis is used to provide an appropriate
discrete and finite basis for treating the continuum part of the spectrum of
the projectile. The continuum-discretized coupled channels framework is used
for the scattering calculations. The formalism is applied to different
reactions, 6He+12C at 229.8 MeV, 6He+64Zn at 10 and 13.6 MeV, and 6He+208Pb at
22 MeV, induced by the Borromean nucleus 6He. Both the Coulomb and nuclear
interactions with a target are taken into account.


title: Hydrostatic pressure study of single-crystalline UNi0.5Sb2

abstract:
  We studied single-crystals of the antiferromagnetic compound UNi0.5Sb2 (TN ~
161 K) by means of measurements of magnetic susceptibility (chi), specific heat
(Cp), and electrical resistivity (rho) at ambient pressure, and resistivity
under hydrostatic pressures up to 20 kbar, in the temperature range from 1.9 to
300 K. The thermal coefficient of the electrical resistivity (drho/dT) changes
drastically from positive below TN to negative above, reflecting the loss of
spin-disorder scattering in the ordered phase. Two small features in the rho vs
T data centered near 40 and 85 K correlate well in temperature with features in
the magnetic susceptibility and are consistent with other data in the
literature. These features are quite hysteretic in temperature, i.e., the
difference between the warming and cooling cycles are about 10 and 6 K,
respectively. The effect of pressure is to raise TN at the approximate rate of
0.76 K/kbar, while progressively suppressing the amplitude of the small
features in rho vs T at lower temperatures and increasing the thermal
hysteresis.


title: The foam and the matrix factorization sl3 link homologies are equivalent

abstract:
  We prove that the foam and matrix factorization universal rational sl3 link
homologies are naturally isomorphic as projective functors from the category of
link and link cobordisms to the category of bigraded vector spaces.


title:
Differential equations driven by rough paths: an approach via discrete
  approximation

abstract:
  A theory of differential equations driven by a non-differentiable path has
recently been developed by Lyons. We develop an alternative approach to this
theory, using (modified Euler approximations), and investigate its
applicability to stochastic differential equations driven by Brownian motion.
We also give some other examples showing that the main results are reasonably
sharp.


title:
Flux line lattice state versus magnetism in electron-doped cuprate
  superconductor Sr_{1-x}La_{x}CuO_{2}

abstract:
  The microscopic details of flux line lattice state studied by muon spin
rotation is reported in an electron-doped high-$T_{\rm c}$ cuprate
superconductor, Sr$_{1-x}$La$_{x}$CuO$_{2}$ (SLCO, $x=0.10$--0.15). A clear
sign of phase separation between magnetic and non-magnetic phases is observed,
where the effective magnetic penetration depth [$\lambda\equiv\lambda(T,H)$] is
determined selectively for the latter phase. The extremely small value of
$\lambda(0,0)$ %versus $T_{\rm c}$ and corresponding large superfluid density
($n_s \propto \lambda^{-2}$) is consistent with presence of a large Fermi
surface with carrier density of $1+x$, which suggests the breakdown of the
"doped Mott insulator" even at the "optimal doping" in SLCO. Moreover, a
relatively weak anisotropy in the superconducting order parameter is suggested
by the field dependence of $\lambda(0,H)$. These observations strongly suggest
that the superconductivity in SLCO is of a different class from hole-doped
cuprates.


title:
NGC 346 in the Small Magellanic Cloud. III. Recent Star Formation and
  Stellar Clustering Properties in the Bright HII Region N 66

abstract:
  In the third part of our photometric study of the star-forming region NGC
346/N~66 and its surrounding field in the Small Magellanic Cloud (SMC), we
focus on the large number of low-mass pre-main sequence (PMS) stars revealed by
the Hubble Space Telescope Observations with the Advanced Camera for Surveys.
We investigate the origin of the observed broadening of the pre-main sequence
population in the $V-I$, $V$ CMD. The most likely explanations are either the
presence of differential reddening or an age spread among the young stars.
Assuming the latter, simulations indicate that we cannot exclude the
possibility that stars in NGC 346 might have formed in two distinct events
occurring about 10 and 5 Myr ago, respectively. We find that the PMS stars are
not homogeneously distributed across NGC 346, but instead are grouped in at
least five different clusters. On spatial scales from 0.8$''$ to 8$''$ (0.24 to
2.4 pc at the distance of the SMC) the clustering of the PMS stars as computed
by a two-point angular correlation function is self-similar with a power law
slope $\gamma \approx -0.3$. The clustering properties are quite similar to
Milky Way star forming regions like Orion OB or $\rho$ Oph. Thus molecular
cloud fragmentation in the SMC seems to proceed on the same spatial scales as
in the Milky Way. This is remarkable given the differences in metallicity and
hence dust content between SMC and Milky Way star forming regions.


title:
The Ultraviolet Spectra of the Weak Emission Line Central Stars of
  Planetary Nebulae

abstract:
  The ultraviolet spectra of all ``weak emission line central stars of
planetary nebulae'' (WELS) with available IUE data are presented and discussed.
We performed line identifications, equivalent width and flux measurements for
several features in their spectra. We found that the WELS can be divided in
three different groups regarding their UV: i) Strong P-Cygni profiles (mainly
in CIV 1549); ii) Weak P-Cygni features and iii) Absence of P-Cygni profiles.
The last group encompasses stars with a featureless UV spectrum or with intense
emission lines and a weak continuum, which are most likely of nebular origin.
We have measured wind terminal velocities for all objects presenting P-Cygni
profiles in N V 1238 and/or C IV 1549. The results obtained were compared to
the UV data of the two prototype stars of the [WC]-PG 1159 class, namely, A30
and A78. For WELS presenting P-Cygnis, most of the terminal velocities fall in
the range ~1000-1500 km/s, while [WC]-PG 1159 stars possess much higher values,
of about 3000 km/s. The [WC]-PG1159 stars are characterized by intense,
simultaneous P-Cygni emissions in the 1150-2000A interval of N V 1238, O V 1371
and C IV 1549. In contrast, we found that O V 1371 is very weak or absent in
the WELS spectra. On the basis of the ultraviolet spectra alone, our findings
indicate that [WC]-PG 1159 stars are distinct from the WELS, contrary to
previous claims in the literature.


title: On the cyclotomic Hecke algebras of complex reflection groups

abstract:
  Following the definition of Rouquier for the "families of characters" of a
Weyl group and its generalization to the case of complex reflection groups,
already appeared in the works of Broue-Kim and Malle-Rouquier, we show that
these "families" depend on a numerical datum of the group, its "essential
hyperplanes". Using this characterization, we provide the algorithm and the
results of the determination of the Rouquier blocks of the cyclotomic Hecke
algebras of all exceptional complex reflection groups.


title: Beyond the Standard Model at the LHC and Beyond

abstract:
  Many of the open questions beyond the Standard Model will be addressed by the
LHC, including the origin of mass, supersymmetry, dark matter and the
possibility of large extra dimensions. A linear e+ e- collider (LC) with
sufficient centre-of-mass energy would add considerable value to the
capabilities of the LHC.


title: Study of lin||lin CPT for application in vapour cell atomic clocks

abstract:
  We evaluate the use of Coherent Population Trapping (CPT) excited with
parallely polarized laser fields in vapour cell atomic clocks. We study the
resonance shape, the discriminator slope and signal-to-noise ratio as a
function of relevant parameters such as the laser frequency detuning and the
applied magnetic field. We show that a stability of $6 \cdot 10^{-12}$
$\tau^{-1/2}$ may be reached in a compact system using a modulated VCSEL.


title: Many-body methods for nuclear systems at subnuclear densities

abstract:
  This article provides a concise review of selected topics in the many-body
physics of low density nuclear systems. The discussion includes the
condensation of alpha particles in supernova envelopes, formation of three-body
bound states and the BEC-BCS crossover in dilute nuclear matter, and neutrino
production in $S$-wave paired superfluid neutron matter.


title:
Intermediate-mass black holes and ultraluminous X-ray sources in the
  Cartwheel ring galaxy

abstract:
  Chandra and XMM-Newton observations of the Cartwheel galaxy show ~17 bright
X-ray sources (>~5x10^38 erg s^-1), all within the gas-rich outer ring. We
explore the hypothesis that these X-ray sources are powered by
intermediate-mass black holes (IMBHs) accreting gas or undergoing mass transfer
from a stellar companion. To this purpose, we run N-body/SPH simulations of the
galaxy interaction which might have led to the formation of Cartwheel, tracking
the dynamical evolution of two different IMBH populations: halo and disc IMBHs.
Halo IMBHs cannot account for the observed X-ray sources, as only a few of them
cross the outer ring. Instead, more than half of the disc IMBHs are pulled in
the outer ring as a consequence of the galaxy collision. However, also in the
case of disc IMBHs, accretion from surrounding gas clouds cannot account for
the high luminosities of the observed sources. Finally, more than 500 disc
IMBHs are required to produce <~15 X-ray sources via mass transfer from very
young stellar companions. Such number of IMBHs is very large and implies
extreme assumptions. Thus, the hypothesis that all the observed X-ray sources
in Cartwheel are associated with IMBHs is hardly consistent with our
simulations, even if it is still possible that IMBHs account for the few
(<~1-5) brightest ultraluminous X-ray sources (ULXs).


title: Interactive Visualization Package for 4D Lattice Field Theories

abstract:
  Recent interest in exploring local vacuum structure of QCD through the
properties of the eigenmodes of the lattice Dirac operators rises again the
challenge to visualize four-dimensional objects and structures which appear in
lattice field theories. In spite of complex and powerful commercial
visualization software packages on the market, there are reasons to develop
Interactive Visualization Package (IVP). We believe that an apprehension of the
complex structures is possible only through the interactive approach, with the
user being able to manipulate data representations and slices through the
lattice in real-time. Further insight should also be gained by an interactive
parallel examination of different physical quantities, e.g. eigenmode density
with topological charge or action densities. Finally, thanks to constantly
falling hardware prices, IVP makes it possible to use almost any Linux PC as a
visualization tool for research in lattice field theory.


title:
Metadynamic sampling of the free energy landscapes of proteins coupled
  with a Monte Carlo algorithm

abstract:
  Metadynamics is a powerful computational tool to obtain the free energy
landscape of complex systems. The Monte Carlo algorithm has proven useful to
calculate thermodynamic quantities associated with simplified models of
proteins, and thus to gain an ever-increasing understanding on the general
principles underlying the mechanism of protein folding. We show that it is
possible to couple metadynamics and Monte Carlo algorithms to obtain the free
energy of model proteins in a way which is computationally very economical.


title: Kramers-Wannier dualities for WZW theories and minimal models

abstract:
  We study Kramers-Wannier dualities for Wess-Zumino-Witten theories and
(super-)minimal models in the Cardy case, i.e. the case with bulk partition
function given by charge conjugation. Using the TFT approach to full rational
conformal field theories, we classify those dualities that preserve all chiral
symmetries. Dualities turn out to exist for small levels only.


title: Time-dependent Effects in Photospheric-Phase Type II Supernova Spectra

abstract:
  Spectroscopic modeling of Type II supernovae (SNe) generally assumes
steady-state. Following the recent suggestion of Utrobin & Chugai, but using
the 1D non-LTE line-blanketed model atmosphere code CMFGEN, we investigate the
effects of including time-dependent terms that appear in the statistical and
radiative equilibrium equations. We base our discussion on the ejecta
properties and the spectroscopic signatures obtained from time-dependent
simulations, investigating different ejecta configurations, and covering their
evolution from one day to six weeks after shock breakout. Compared to
equivalent steady-state models, our time-dependent models produce SN ejecta
that are systematically over-ionized, affecting helium at one week after
explosion, but ultimately affecting all ions after a few weeks. While the
continuum remains essentially unchanged, time-dependence effects on observed
spectral lines are large. At the recombination epoch, HI lines and NaID are
considerably stronger and broader than in equivalent steady-state models, while
CaII8500A is weakened. If time dependence is allowed for, the HeI lines at
5875A and 10830A appear about 3 times stronger at one week, and HeI10830A
persists as a blue-shifted absorption feature even at 6 weeks after explosion.
Time dependence operates through the energy gain from changes in ionization and
excitation, and, perhaps more universally across SN types, from the competition
between recombination and expansion, which in-turn, can be affected by
optical-depth effects. Our time-dependent models compare well with observations
of the low-luminosity low-velocity SN 1999br and the more standard SN 1999em,
reproducing the Halpha line strength at the recombination epoch, and without
the need for setting unphysical requirements on the magnitude of nickel mixing.


title:
Development of an n-channel CCD, CCD-NeXT1, for Soft X-ray Imager
  onboard the NeXT satellite

abstract:
  NeXT (New X-ray Telescope) is the next Japanese X-ray astronomical satellite
mission after the Suzaku satellite. NeXT aims to perform wide band imaging
spectroscopy. Due to the successful development of a multilayer coated mirror,
called a supermirror, NeXT can focus X-rays in the energy range from 0.1 keV up
to 80 keV. To cover this wide energy range, we are in the process of developing
a hybrid X-ray camera, Wideband X-ray Imager (WXI) as a focal plane detector of
the supermirror. The WXI consists of X-ray CCDs (SXI) and CdTe pixelized
detectors (HXI), which cover the lower and higher X-ray energy bands of 0.1-80
keV, respectively. The X-ray CCDs of the SXI are stacked above the CdTe
pixelized detectors of the HXI. The X-ray CCDs of the SXI detect soft X-rays
below $\sim$ 10 keV and allow hard X-rays pass into the CdTe detectors of the
HXI without loss. Thus, we have been developing a "back-supportless CCD" with a
thick depletion layer, a thinned silicon wafer, and a back-supportless
structure. In this paper, we report the development and performances of an
evaluation model of CCD for the SXI, "CCD-NeXT1". We successfully fabricated
two types of CCD-NeXT1, unthinned CCDs with 625-um thick wafer and 150-um thick
thinned CCDs. By omitting the polishing process when making the thinned CCDs,
we confirmed that the polishing process does not impact the X-ray performance.
In addition, we did not find significant differences in the X-ray performance
between the two types of CCDs. The energy resolution and readout noise are
$\sim$ 140 eV (FWHM) at 5.9 keV and $\sim$5 electrons (RMS), respectively. The
estimated thickness of the depletion layer is $\sim$80 um. The performances
almost satisfy the requirements of the baseline plan of the SXI.


title:
Measurements of the observed cross sections for exclusive light hadron
  production in e^+e^- annihilation at \sqrt{s}= 3.773 and 3.650 GeV

abstract:
  By analyzing the data sets of 17.3 pb$^{-1}$ taken at $\sqrt{s}=3.773$ GeV
and 6.5 pb$^{-1}$ taken at $\sqrt{s}=3.650$ GeV with the BESII detector at the
BEPC collider, we have measured the observed cross sections for 12 exclusive
light hadron final states produced in $e^+e^-$ annihilation at the two energy
points. We have also set the upper limits on the observed cross sections and
the branching fractions for $\psi(3770)$ decay to these final states at 90%
C.L.


title: Dynamics of Fractal Solids

abstract:
  We describe the fractal solid by a special continuous medium model. We
propose to describe the fractal solid by a fractional continuous model, where
all characteristics and fields are defined everywhere in the volume but they
follow some generalized equations which are derived by using integrals of
fractional order. The order of fractional integral can be equal to the fractal
mass dimension of the solid. Fractional integrals are considered as an
approximation of integrals on fractals. We suggest the approach to compute the
moments of inertia for fractal solids. The dynamics of fractal solids are
described by the usual Euler's equations. The possible experimental test of the
continuous medium model for fractal solids is considered.


title: Mapping Cartesian Coordinates into Emission Coordinates: some Toy Models

abstract:
  After briefly reviewing the relativistic approach to positioning systems
based on the introduction of the emission coordinates, we show how explicit
maps can be obtained between the Cartesian coordinates and the emission
coordinates, for suitably chosen set of emitters, whose world-lines are
supposed to be known by the users. We consider Minkowski space-time and the
space-time where a small inhomogeineity is introduced (i.e. a small
"gravitational" field), both in 1+1 and 1+3 dimensions.


title: Wireless Local Area Networks with Multiple-Packet Reception Capability

abstract:
  Thanks to its simplicity and cost efficiency, wireless local area network
(WLAN) enjoys unique advantages in providing high-speed and low-cost wireless
services in hot spots and indoor environments. Traditional WLAN
medium-access-control (MAC) protocols assume that only one station can transmit
at a time: simultaneous transmissions of more than one station causes the
destruction of all packets involved. By exploiting recent advances in PHY-layer
multiuser detection (MUD) techniques, it is possible for a receiver to receive
multiple packets simultaneously. This paper argues that such multipacket
reception (MPR) capability can greatly enhance the capacity of future WLANs. In
addition, it provides the MAC-layer and PHY-layer designs needed to achieve the
improved capacity. First, to demonstrate MUD/MPR as a powerful
capacity-enhancement technique, we prove a "super-linearity" result, which
states that the system throughput per unit cost increases as the MPR capability
increases. Second, we show that the commonly deployed binary exponential
backoff (BEB) algorithm in today's WLAN MAC may not be optimal in an MPR
system, and that the optimal backoff factor increases with the MPR capability:
the number of packets that can be received simultaneously. Third, based on the
above insights, we design a joint MAC-PHY layer protocol for an IEEE
802.11-like WLAN that incorporates advanced PHY-layer blind detection and MUD
techniques to implement MPR


title:
Water maser variability over 20 years in a large sample of star-forming
  regions: the complete database

abstract:
  Context. Water vapor emission at 22 GHz from masers associated with
star-forming regions is highly variable. Aims. We present a database of up to
20 years of monitoring of a sample of 43 masers within star-forming regions.
The sample covers a large range of luminosities of the associated IRAS source
and is representative of the entire population of H2O masers of this type. The
database forms a good starting point for any further study of H2O maser
variability. Methods. The observations were obtained with the Medicina 32-m
radiotelescope, at a rate of 4-5 observations per year. Results. To provide a
database that can be easily accessed through the web, we give for each source:
plots of the calibrated spectra, the velocity-time-flux density plot, the light
curve of the integrated flux, the lower and upper envelopes of the maser
emission, the mean spectrum, and the rate of the maser occurrence as a function
of velocity. Figures for just one source are given in the text for
representative purposes. Figures for all the sources are given in electronic
form in the on-line appendix. A discussion of the main properties of the H2O
variability in our sample will be presented in a forthcoming paper.


title: Spin-rotation couplings: spinning test particles and Dirac field

abstract:
  The hypothesis of coupling between spin and rotation introduced long ago by
Mashhoon is examined in the context of "1+3" and "3+1" space-time splitting
techniques, either in special or in general relativity. Its content is
discussed in terms of classical (Mathisson-Papapetrou-Dixon-Souriou model) as
well as quantum physics (Foldy-Wouthuysen transformation for the Dirac field in
an external field), reviewing and discussing all the relevant theoretical
literature concerning the existence of such effect. Some original contributions
are also included.


title: On Q-conic bundles, II

abstract:
  A $\mathbb Q$-conic bundle germ is a proper morphism from a threefold with
only terminal singularities to the germ $(Z \ni o)$ of a normal surface such
that fibers are connected and the anti-canonical divisor is relatively ample.
We obtain the complete classification of $\mathbb Q$-conic bundle germs when
the base surface germ is singular. This is a generalization of our previous
paper math/0603736, which further assumed that the fiber over $o$ is
irreducible.


title:
Origin of the Verwey transition in magnetite: Group theory, electronic
  structure, and lattice dynamics study

abstract:
  The Verwey phase transition in magnetite has been analyzed using the group
theory methods. It is found that two order parameters with the symmetries $X_3$
and $\Delta_5$ induce the structural transformation from the high-temperature
cubic to the low-temperature monoclinic phase. The coupling between the order
parameters is described by the Landau free energy functional. The electronic
and crystal structure for the cubic and monoclinic phases were optimized using
the {\it ab initio} density functional method. The electronic structure
calculations were performed within the generalized gradient approximation
including the on-site interactions between 3d electrons at iron ions -- the
Coulomb element $U$ and Hund's exchange $J$. Only when these local interactions
are taken into account, the phonon dispersion curves, obtained by the direct
method for the cubic phase, reproduce the experimental data. It is shown that
the interplay of local electron interations and the coupling to the lattice
drives the phonon order parameters and is responsible for the opening of the
gap at the Fermi energy. Thus, it is found that the metal-insulator transition
in magnetite is promoted by local electron interactions, which significantly
amplify the electron-phonon interaction and stabilize weak charge order
coexisting with orbital order of the occupied $t_{2g}$ states at Fe ions. This
provides a scenario to understand the fundamental problem of the origin of the
Verwey transition in magnetite.


title:
Global stability of travelling fronts for a damped wave equation with
  bistable nonlinearity

abstract:
  We consider the damped wave equation \alpha u_tt + u_t = u_xx - V'(u) on the
whole real line, where V is a bistable potential. This equation has travelling
front solutions of the form u(x,t) = h(x-st) which describe a moving interface
between two different steady states of the system, one of which being the
global minimum of V. We show that, if the initial data are sufficiently close
to the profile of a front for large |x|, the solution of the damped wave
equation converges uniformly on R to a travelling front as t goes to plus
infinity. The proof of this global stability result is inspired by a recent
work of E. Risler and relies on the fact that our system has a Lyapunov
function in any Galilean frame.


title: N-body simulations of star clusters

abstract:
  Two aspects of our recent N-body studies of star clusters are presented: (1)
What impact does mass segregation and selective mass loss have on integrated
photometry? (2) How well compare results from N-body simulations using NBODY4
and STARLAB/KIRA?


title:
Keck spectroscopy of the faint dwarf elliptical galaxy population in the
  Perseus Cluster core: mixed stellar populations and a flat luminosity
  function

abstract:
  We present the result of a photometric and Keck-LRIS spectroscopic study of
dwarf galaxies in the core of the Perseus Cluster, down to a magnitude of M_B =
-12.5. Spectra were obtained for twenty-three dwarf-galaxy candidates, from
which we measure radial velocities and stellar population characteristics from
absorption line indices. From radial velocities obtained using these spectra we
confirm twelve systems as cluster members, with the remaining eleven as
non-members. Using these newly confirmed cluster members, we are able to extend
the confirmed colour-magnitude relation for the Perseus Cluster down to M_B =
-12.5. We confirm an increase in the scatter about the colour magnitude
relationship below M_B = -15.5, but reject the hypothesis that very red dwarfs
are cluster members. We measure the faint-end slope of the luminosity function
between M_B = -18 and M_B = -12.5, finding alpha = -1.26 \pm 0.06, which is
similar to that of the field. This implies that an overabundance of dwarf
galaxies does not exist in the core of the Perseus Cluster. By comparing metal
and Balmer absorption line indices with alpha-enhanced single stellar
population models, we derive ages and metallicities for these newly confirmed
cluster members. We find two distinct dwarf elliptical populations: an old,
metal poor population with ages ~ 8 Gyr and metallicities [Fe/H] < -0.33, and a
young, metal rich population with ages < 5 Gyr and metallicities [Fe/H] >
-0.33. Dwarf galaxies in the Perseus Cluster are therefore not a simple
homogeneous population, but rather exhibit a range in age and metallicity.


title: The eigenvalues of limits of radial Toeplitz operators

abstract:
  Let $A^2$ be the Bergman space on the unit disk. A bounded operator $S$ on
$A^2$ is called radial if $Sz^n = \lambda_n z^n$ for all $n\ge 0$, where
$\lambda_n$ is a bounded sequence of complex numbers. We characterize the
eigenvalues of radial operators that can be approximated by Toeplitz operators
with bounded symbols.


title:
Analysis and calibration of CaII triplet spectroscopy of Red Giant
  Branch stars from VLT/FLAMES observations

abstract:
  We demonstrate that low resolution CaII triplet (CaT) spectroscopic estimates
of the overall metallicity ([Fe/H]) of individual Red Giant Branch (RGB) stars
in two nearby dwarf spheroidal galaxies (dSphs) agree to +-0.1-0.2 dex with
detailed high resolution spectroscopic determinations for the same stars over
the range -2.5 < [Fe/H] < -0.5. For this study we used a sample of 129 stars
observed in low and high resolution mode with VLT/FLAMES in the Sculptor and
Fornax dSphs. We also present the data reduction steps we used in our low
resolution analysis and show that the typical accuracy of our velocity and CaT
[Fe/H] measurement is ~2 km/s and 0.1 dex respectively. We conclude that
CaT-[Fe/H] relations calibrated on globular clusters can be applied with
confidence to RGB stars in composite stellar populations over the range -2.5 <
[Fe/H] < -0.5.


title: Hard X-rays from Galaxy Clusters and SIMBOL-X

abstract:
  Non thermal emission from galaxy clusters demonstrates the existence of
relativistic particles and magnetic fields in the Intra Cluster Medium (ICM).
Present instruments do not allow to firmly establish the energy associated to
these components. In a few years gamma ray observations will put important
constraints on the energy content of non thermal hadrons in clusters, while the
combination of radio and hard X-ray data will be crucial to measure the energy
content in the form of relativistic electrons and magnetic field. SIMBOL-X is
expected to drive an important breakthrough in the field also because it is
expected to operate in combination with the forthcoming low frequency radio
telescopes (LOFAR, LWA). In this contribution we report first estimates of
statistical properties of the hard X-ray emission in the framework of the
re-acceleration model. This model allows to reproduce present radio data for
Radio Halos and to derive expectations for future low frequency radio
observations, and thus our calculations provide hints for observational
strategies for future radio and hard--X-ray combined observations.


title: Bipartite Mean Field Spin Systems. Existence and Solution

abstract:
  A mean field spin system consisting two interacting groups each with
homogeneous interaction coefficients is introduced and studied. Existence of
the thermodynamic limit is shown by an asymptotic sub-addittivity method and
factorization of correlation functions is proved almost everywhere. The free
energy solution of the model is obtained by upper and lower bounds and by
showing that their difference vanishes for large volumes.


title:
Cosmic rays and Radio Halos in galaxy clusters : new constraints from
  radio observations

abstract:
  Clusters of galaxies are sites of acceleration of charged particles and
sources of non-thermal radiation. We report on new constraints on the
population of cosmic rays in the Intra Cluster Medium (ICM) obtained via radio
observations of a fairly large sample of massive, X-ray luminous, galaxy
clusters in the redshift interval 0.2--0.4. The bulk of the observed galaxy
clusters does not show any hint of Mpc scale synchrotron radio emission at the
cluster center (Radio Halo). We obtained solid upper limits to the diffuse
radio emission and discuss their implications for the models for the origin of
Radio Halos. Our measurements allow us to derive also a limit to the content of
cosmic ray protons in the ICM. Assuming spectral indices of these protons delta
=2.1-2.4 and microG level magnetic fields, as from Rotation Measures, these
limits are one order of magnitude deeper than present EGRET upper limits, while
they are less stringent for steeper spectra and lower magnetic fields.


title:
The Student ensemble of correlation matrices: eigenvalue spectrum and
  Kullback-Leibler entropy

abstract:
  We study a new ensemble of random correlation matrices related to
multivariate Student (or more generally elliptic) random variables. We
establish the exact density of states of empirical correlation matrices that
generalizes the Marcenko-Pastur result. The comparison between the theoretical
density of states in the Student case and empirical financial data is
surprisingly good, even if we are still able to detect systematic deviations.
Finally, we compute explicitely the Kullback-Leibler entropies of empirical
Student matrices, which are found to be independent of the true correlation
matrix, as in the Gaussian case. We provide numerically exact values for these
Kullback-Leibler entropies.


title: The effect of ozone oxidation on single-walled carbon nanotubes

abstract:
  Exposing single-walled carbon nanotubes to room temperature UV-generated
ozone leads to an irreversible increase in their electrical resistance. We
demonstrate that the increased resistance is due to ozone oxidation on the
sidewalls of the nanotubes rather than at the end caps. Raman and x-ray
photoelectron spectroscopy show an increase in the defect density due to the
oxidation of the nanotubes. Using ultraviolet photoelectron spectroscopy we
show that these defects represent the removal of pi-conjugated electron states
near the Fermi level, leading to the observed increase in electrical
resistance. Oxidation of carbon nanotubes is an important first step in many
chemical functionalization processes. Since the oxidation rate is controllable
with short exposures, UV-generated ozone offers the potential for use as a
low-thermal budget processing tool.


title: Taste violations in the scalar correlator in mixed action simulations

abstract:
  We study the behavior of the isovector scalar correlator, which is
particularly sensitive to lattice artifacts, using domain-wall valence quarks
on a staggered sea (generated by the MILC collaboration). We analyze this
according to the prediction from chiral perturbation theory determined by
Prelovsek, which indicates that the leading unitarity violations come from
taste breaking effects. We show that our data behaves in the way predicted by
Prelovsek, thus verifying that the largest contribution to the violations of
unitarity which arise at finite lattice spacing can be described by the
mixed-action chiral perturbation theory.


title:
On the Satisfiability Threshold and Clustering of Solutions of Random
  3-SAT Formulas

abstract:
  We study the structure of satisfying assignments of a random 3-SAT formula.
In particular, we show that a random formula of density 4.453 or higher almost
surely has no non-trivial "core" assignments. Core assignments are certain
partial assignments that can be extended to satisfying assignments, and have
been studied recently in connection with the Survey Propagation heuristic for
random SAT. Their existence implies the presence of clusters of solutions, and
they have been shown to exist with high probability below the satisfiability
threshold for k-SAT with k>8, by Achlioptas and Ricci-Tersenghi, STOC 2006. Our
result implies that either this does not hold for 3-SAT or the threshold
density for satisfiability in 3-SAT lies below 4.453.
  The main technical tool that we use is a novel simple application of the
first moment method.