title: Local Phase Space - Shaped by Chaos?

abstract:
  We attempt to understand the state of the local phase space by comparing
simulated 2-D velocity distributions to the distribution that is constructed
for the solar neighbourhood, from measurements of stellar radial and transverse
velocities. The joint perurbation of the central bar in the Galaxy and the
spiral pattern is found to be a must, in order to produce successful models of
the local phase space. The existence of chaos is found to be an important
ingredient in the formation of the observed phase space structure.


title: DMRG Simulation of the SU(3) AFM Heisenberg Model

abstract:
  We analyze the antiferromagnetic $\text{SU}(3)$ Heisenberg chain by means of
the Density Matrix Renormalization Group (DMRG). The results confirm that the
model is critical and the computation of its central charge and the scaling
dimensions of the first excited states show that the underlying low energy
conformal field theory is the $\text{SU}(3)_1$ Wess-Zumino-Novikov-Witten
model.


title: Hexagonal spiral growth in the absence of a substrate

abstract:
  Experiments on the formation of spiraling hexagons (350 - 1000 nm in width)
from a solution of nanoparticles are presented. Transmission electron
microscopy images of the reaction products of chemically synthesized cadmium
nanocrystals indicate that the birth of the hexagons proceeds without
assistance from static screw or edge dislocatons, that is, they spiral without
constraints provided by an underlying substrate. Instead, the apparent growth
mechanism relies on what we believe is a dynamical dislocation identified as a
dense aggregate of small nanocrystals that straddles the spiraling hexagon at
the crystal surface. This nanocrystal bundle, which we term the "feeder", also
appears to release nanocrystals into the spiral during the growth process.


title:
A concentration inequality for interval maps with an indifferent fixed
  point

abstract:
  For a map of the unit interval with an indifferent fixed point, we prove an
upper bound for the variance of all observables of $n$ variables
$K:[0,1]^n\to\R$ which are componentwise Lipschitz. The proof is based on
coupling and decay of correlation properties of the map. We then give various
applications of this inequality to the almost-sure central limit theorem, the
kernel density estimation, the empirical measure and the periodogram.


title:
Uniqueness of Invariant Lagrangian Graphs in a Homology or a Cohomology
  Class

abstract:
  Given a smooth compact Riemannian manifold $M$ and a Hamiltonian $H$ on the
cotangent space $T^*M$, strictly convex and superlinear in the momentum
variables, we prove uniqueness of certain ergodic invariant Lagrangian graphs
within a given homology or cohomology class. In particular, in the context of
quasi-integrable Hamiltonian systems, our result implies global uniqueness of
Lagrangian KAM tori with rotation vector $\rho$. This result extends
generically to the $C^0$-closure of KAM tori.


title:
SMA observations of young disks: separating envelope, disk, and stellar
  masses in class I YSOs

abstract:
  (abbreviated) We aim to determine the masses of the envelopes, disks, and
central stars of young stellar objects (YSOs) in the Class I stage. We observed
the embedded Class I objects IRS 63 and Elias 29 in the rho Ophiuchi
star-forming region with the Submillimeter Array (SMA) at 1.1 mm. IRS 63 and
Elias 29 are both clearly detected in the continuum, with peak fluxes of 459
resp. 47 mJy/beam. The continuum emission toward Elias 29 is clearly resolved,
whereas IRS 63 is consistent with a point source down to a scale of 3 arcsec
(400 AU). The SMA data are combined with single-dish data, and disk masses of
0.055 and >= 0.007 MSun and envelope masses of 0.058 and >= 0.058 MSun are
empirically determined for IRS 63 and Elias 29, respectively. The disk+envelope
systems are modelled with the axisymmetric radiative-transfer code RADMC,
yielding disk and envelope masses that differ from the empirical results by
factors of a few. HCO+ J = 3-2 is detected toward both sources, HCN J = 3-2 is
not. The HCO+ position-velocity diagrams are indicative of Keplerian rotation.
For a fiducial inclination of 30 degrees, we find stellar masses of 0.37 +/-
0.13 and 2.5 +/- 0.6 MSun for IRS 63 and Elias 29, respectively. We conclude
that the sensitivity and spatial resolution of the SMA at 1.1 mm allow a good
separation of the disks around Class I YSOs from their circumstellar envelopes
and environments, and the spectral resolution makes it possible to resolve
their dynamical structure and estimate the masses of the central stars. The
ratios of the envelope and disk masses are found to be 0.2 and 6 for IRS 63 and
Elias 29, respectively. This is lower than the values for Class 0 sources,
which have Menv/Mdisk >= 10, suggesting that this ratio is a tracer of the
evolutionary stage of a YSO.


title: Mixing of heavy baryons in the bag model calculations

abstract:
  Spin-spin interaction causes the mixing between ground state wave functions
of baryons containing three quarks of different flavors. We examine the effect
of this mixing on the baryon masses in the framework of the modified bag model.


title:
Lowest Landau Level vortex structure of a Bose-Einstein condensate
  rotating in a harmonic plus quartic trap

abstract:
  We investigate the vortex patterns appearing in a two-dimensional annular
Bose-Einstein condensate rotating in a quadratic plus quartic confining
potential. We show that in the limit of small anharmonicity the
Gross-Pitaevskii energy can be minimized amongst the Lowest Landau Level wave
functions and use this particular form to get theoretical results in the spirit
of [A. Aftalion X. Blanc F. Nier, Phys. Rev. A 73, 011601(R) (2006)]. In
particular, we show that the vortex pattern is infinite but not uniform. We
also compute numerically the complete vortex structure: it is an Abrikosov
lattice strongly distorted near the edges of the condensate with multiply
quantized vortices appearing at the center of the trap.


title:
Spherical-separablility of non-Hermitian Hamiltonians and
  pseudo-PT-symmetry

abstract:
  Non-Hermitian but P(phi)T(phi)-symmetrized spherically-separable Dirac and
Schrodinger Hamiltonians are considered. It is observed that the descendant
Hamiltonians H(r), H(theta), and H(phi) play essential roles and offer some
"user-feriendly" options as to which one (or ones) of them is (or are)
non-Hermitian. Considering a P(phi)T(phi)-symmetrized H(phi), we have shown
that the conventional Dirac (relativistic) and Schrodinger (non-relativistic)
energy eigenvalues are recoverable. We have also witnessed an unavoidable
change in the azimuthal part of the general wavefunction. Moreover, setting a
possible interaction V(theta) in the descendant Hamiltonian H(theta) would
manifest a change in the angular theta-dependent part of the general solution
too. Whilst some P(phi)T(phi)-symmetrized H(phi) Hamiltonians are considered, a
recipe to keep the regular magnetic quantum number m, as defined in the regular
traditional Hermitian settings, is suggested. Hamiltonians possess properties
similar to the PT-symmetric ones (here the non-Hermitian P(phi)T(phi)-symmetric
Hamiltonians) are nicknamed as pseudo-PT-symmetric.


title: Stability analysis and \mu-synthesis control of brake systems

abstract:
  The concept of friction-induced brake vibrations, commonly known as judder,
is investigated. Judder vibration is based on the class of geometrically
induced or kinematic constraint instability. After presenting the modal
coupling mechanism and the associated dynamic model, a stability analysis as
well as a sensitivity analysis have been conducted in order to identify
physical parameters for a brake design avoiding friction-induced judder
instability. Next, in order to reduce the size of the instability regions in
relation to possible system parameter combinations, robust stability via
\mu-synthesis is applied. By comparing the unstable regions between the initial
and controlled brake system, some general indications emerge and it appears
that robust stability via \mu-synthesis has some effect on the instability of
the brake system.


title:
Bell inequalities and density matrix for polarization entangled photons
  out of a two-photon cascade in a single quantum dot

abstract:
  We theoretically investigate the joint photodetection probabilities of the
biexciton-exciton cascade in single semiconductor quantum dots and analytically
derive the density matrix and the Bell's inequalities of the entangled state.
Our model includes different mechanisms that may spoil or even destroy
entanglement such as dephasing, energy splitting of the relay excitonic states
and incoherent population exchange between these relay levels. We explicitly
relate the fidelity of entanglement to the dynamics of these processes and
derive a threshold for violation of Bell's inequalities. Applied to standard
InAs/GaAs self-assembled quantum dots, our model indicates that spontaneous
emission enhancement of the excitonic states by cavity effects increases the
fidelity of entanglement to a value allowing for violation of Bell's
inequalities.


title: The wave function of $[\bf{70},1^-]$ baryons in the $1/N_c$ expansion

abstract:
  Much work has been devoted to the study of nonstrange baryons belonging to
the $[\textbf{70},1^-]$ multiplet in the framework of the $1/N_c$ expansion.
Using group theoretical arguments here we examine the relation between the
exact wave function and the approximate one, customarily used in applications
where the system is separated into a ground state core and an excited quark. We
show that the exact and approximate wave functions globally give similar
results for all of mass operators presented in this work. However we find that
the inclusion of operators acting separately on the core and on the excited
quark deteriorates the fit and leads to unsatisfactory values for the
coefficients which encode the quark dynamics. Much better results are obtained
when we include operators acting on the whole system, both for the exact and
the approximate wave function.


title: Scalar mesons from Heavy Flavor Decays

abstract:
  In the past few years the B-factories became unexpected players in the scalar
mesons business: in order to access the CP violation effects, it is necessary
to handle the dynamics of the strong interaction between the final state
hadrons. A number of large statistics studies heavy flavor decays involving a
scalar component have been performed recently by Belle and BaBar, who have
joined CLEOc, BES, E791 and FOCUS in the effort to understand the physics of
the scalar mesons. In this talk, the most recent results from these experiments
will be reviewed, with emphasis on the low energy $K\pi$ system and on the
f0(1370).


title: Strongly Correlated Superconductivity rising from a Pseudo-gap Metal

abstract:
  We solve by Dynamical Mean Field Theory a toy-model which has a phase diagram
strikingly similar to that of high $T_c$ superconductors: a bell-shaped
superconducting region adjacent the Mott insulator and a normal phase that
evolves from a conventional Fermi liquid to a pseudogapped semi-metal as the
Mott transition is approached. Guided by the physics of the impurity model that
is self-consistently solved within Dynamical Mean Field Theory, we introduce an
analytical ansatz to model the dynamical behavior across the various phases
which fits very accurately the numerical data. The ansatz is based on the
assumption that the wave-function renormalization, that is very severe
especially in the pseudogap phase close to the Mott transition, is perfectly
canceled by the vertex corrections in the Cooper pairing channel.A remarkable
outcome is that a superconducting state can develop even from a pseudogapped
normal state, in which there are no low-energy quasiparticles. The overall
physical scenario that emerges, although unraveled in a specific model and in
an infinite-coordination Bethe lattice, can be interpreted in terms of so
general arguments to suggest that it can be realized in other correlated
systems.


title:
Interpretation of the Low-Frequency Peculiarities in the Radio Profile
  Structure of the Crab Pulsar

abstract:
  The theory of magnetized induced scattering off relativistic gyrating
particles is developed. It is directly applicable to the magnetosphere of a
pulsar, in which case the particles acquire gyration energies as a result of
resonant absorption of radio emission. In the course of the radio beam
scattering into background the scattered radiation concentrates along the
ambient magnetic field. The scattering from different harmonics of the particle
gyrofrequency takes place at different characteristic altitudes in the
magnetosphere and, because of the rotational effect, gives rise to different
components in the pulse profile. It is demonstrated that the induced scattering
from the first harmonic into the state under the resonance can account for the
so-called low-frequency component in the radio profile of the Crab pulsar. The
precursor component is believed to result from the induced scattering between
the two states well below the resonance. It is shown that these ideas are
strongly supported by the polarization data observed. Based on an analysis of
the fluctuation behaviour of the scattering efficiencies, the transient
components of a similar nature are predicted for other pulsars.


title:
Lepton Flavor Violating Radion Decays in the Randall-Sundrum Scenario:
  The Thesis

abstract:
  The lepton flavor violating interactions are worthwhile to examine since they
are sensitive to physics beyond the Standard Model. The simplest extension of
the Standard Model promoting the lepton flavor violating interactions are the
so called two Higgs doublet model which contains an additional Higgs doublet
carrying the same quantum numbers as the first one. In this model, the lepton
flavor violating interactions are induced by new scalar Higgs bosons, scalar
h^{0} and pseudo scalar A^{0}, and Yukawa couplings, appearing as free
parameters, are determined by using the experimental data. On the other hand,
the possible extra dimensions are interesting in the sense that they ensure a
solution to the hierarchy and cosmological constant problems and also result in
the enhancement in the physical quantities of various processes. In the present
work, we predict the branching ratios of lepton flavor violating radion decays
r-> e^{\pm},\mu^{\pm}, r-> e^{\pm},\tau^{\pm} and r->\mu^{\pm},\tau^{\pm} in
the two Higgs doublet model, including a single extra dimension, in the
framework of the Randall Sundrum scenario. We observed that the branching
ratios of the processes we study are at most at the order of 10^{-8} for the
small values of radion mass and it decreases with the increasing values of the
radion mass. Among the LFV decays we study, the r->\mu^{\pm},\tau^{\pm} decay
would be the most suitable one to measure its branching ratio.


title: Determination of target thickness and luminosity from beam energy losses

abstract:
  The repeated passage of a coasting ion beam of a storage ring through a thin
target induces a shift in the revolution frequency due to the energy loss in
the target. Since the frequency shift is proportional to the beam-target
overlap, its measurement offers the possibility of determining the target
thickness and hence the corresponding luminosity in an experiment. This effect
has been investigated with an internal proton beam of energy 2.65 GeV at the
COSY-J\"ulich accelerator using the ANKE spectrometer and a hydrogen
cluster-jet target. Possible sources of error, especially those arising from
the influence of residual gas in the ring, were carefully studied, resulting in
a accuracy of better than 5%. The luminosity determined in this way was used,
in conjunction with measurements in the ANKE forward detector, to determine the
cross section for elastic proton-proton scattering. The result is compared to
published data as well as to the predictions of a phase shift solution. The
practicability and the limitations of the energy-loss method are discussed.


title:
Shallow, Low, and Light Trees, and Tight Lower Bounds for Euclidean
  Spanners

abstract:
  We show that for every $n$-point metric space $M$ there exists a spanning
tree $T$ with unweighted diameter $O(\log n)$ and weight $\omega(T) = O(\log n)
\cdot \omega(MST(M))$. Moreover, there is a designated point $rt$ such that for
every point $v$, $dist_T(rt,v) \le (1+\epsilon) \cdot dist_M(rt,v)$, for an
arbitrarily small constant $\epsilon > 0$. We extend this result, and provide a
tradeoff between unweighted diameter and weight, and prove that this tradeoff
is \emph{tight up to constant factors} in the entire range of parameters. These
results enable us to settle a long-standing open question in Computational
Geometry. In STOC'95 Arya et al. devised a construction of Euclidean Spanners
with unweighted diameter $O(\log n)$ and weight $O(\log n) \cdot
\omega(MST(M))$. Ten years later in SODA'05 Agarwal et al. showed that this
result is tight up to a factor of $O(\log \log n)$. We close this gap and show
that the result of Arya et al. is tight up to constant factors.


title: Strange Quark Contribution to the Nucleon - (Dissertation)

abstract:
  The strangeness contribution to the electric and magnetic properties of the
nucleon has been under investigation experimentally for many years. Lattice
Quantum Chromodynamics (LQCD) gives theoretical predictions of these
measurements by implementing the continuum gauge theory on a discrete,
mathematical Euclidean space-time lattice which provides a cutoff removing the
ultra-violet divergences. In this dissertation we will discuss effective
methods using LQCD that will lead to a better determination of the strangeness
contribution to the nucleon properties. Strangeness calculations are demanding
technically and computationally. Sophisticated techniques are required to carry
them to completion. In this thesis, new theoretical and computational methods
for this calculation such as twisted mass fermions, perturbative subtraction,
and General Minimal Residual (GMRES) techniques which have proven useful in the
determination of these form factors will be investigated. Numerical results of
the scalar form factor using these techniques are presented. These results give
validation to these methods in future calculations of the strange quark
contribution to the electric and magnetic form factors.


title: Noncommutative Black Hole Thermodynamics

abstract:
  We give a general derivation, for any static spherically symmetric metric, of
the relation $T_h=\frac{\cal K}{2\pi}$ connecting the black hole temperature
($T_h$) with the surface gravity ($\cal K$), following the tunneling
interpretation of Hawking radiation. This derivation is valid even beyond the
semi classical regime i. e. when quantum effects are not negligible. The
formalism is then applied to a spherically symmetric, stationary noncommutative
Schwarzschild space time. The effects of back reaction are also included. For
such a black hole the Hawking temperature is computed in a closed form. A
graphical analysis reveals interesting features regarding the variation of the
Hawking temperature (including corrections due to noncommutativity and back
reaction) with the small radius of the black hole. The entropy and tunneling
rate valid for the leading order in the noncommutative parameter are
calculated. We also show that the noncommutative Bekenstein-Hawking area law
has the same functional form as the usual one.


title: Clustering and collision of inertial particles in random velocity fields

abstract:
  The influence of clustering on the collision rate of inertial particles in a
smooth random velocity field, mimicking the smaller scales of a turbulent flow,
is analyzed. For small values of the the ratio between the relaxation time of
the particle velocity and the characteristic time of the field, the effect of
clusters is to make more energetic collisions less likely. The result is
independent of the flow dimensionality and is due only to the origin of
collisions in the process of caustic formation.


title: DOPING: a New Non-parametric Deprojection Scheme

abstract:
  We present a new non-parametric deprojection algorithm DOPING (Deprojection
of Observed Photometry using and INverse Gambit), that is designed to extract
the three dimensional luminosity density distribution $\rho$, from the observed
surface brightness profile of an astrophysical system such as a galaxy or a
galaxy cluster, in a generalised geometry, while taking into account changes in
the intrinsic shape of the system. The observable is the 2-D surface brightness
distribution of the system. While the deprojection schemes presented hitherto
have always worked within the limits of an assumed intrinsic geometry, in
DOPING, geometry and inclination can be provided as inputs. The $\rho$ that is
most likely to project to the observed brightness data is sought; the
maximisation of the likelihood is performed with the Metropolis algorithm.
Unless the likelihood function is maximised, $\rho$ is tweaked in shape and
amplitude, while maintaining positivity, but otherwise the luminosity
distribution is allowed to be completely free-form. Tests and applications of
the algorithm are discussed.


title:
Higgs boson searches in CP-conserving and CP-violating MSSM scenarios
  with the DELPHI detector

abstract:
  This paper presents the final interpretation of the results from DELPHI on
the searches for Higgs bosons in the Minimal Supersymmetric extension of the
Standard Model (MSSM). A few representative scenarios are considered, that
include CP conservation and explicit CP violation in the Higgs sector. The
experimental results encompass the searches for neutral Higgs bosons at LEP1
and LEP2 in final states as expected in the MSSM, as well as LEP2 searches for
charged Higgs bosons and for neutral Higgs bosons decaying into hadrons
independent of the quark flavour. The data reveal no significant excess with
respect to background expectations. The results are translated into excluded
regions of the parameter space in the various scenarios. In the CP-conserving
case, these lead to limits on the masses of the lightest scalar and
pseudoscalar Higgs bosons, h and A, and on tan(beta). The dependence of these
limits on the top quark mass is discussed. Allowing for CP violation reduces
the experimental sensitivity to Higgs bosons. It is shown that this effect
depends strongly on the values of the parameters responsible for CP violation
in the Higgs sector.


title:
Molecules in clusters: the case of planar LiBeBCNOF built from a
  triangular form LiOB and a linear four-center species FBeCN

abstract:
  Krueger some years ago proposed a cluster LiBeBCNOF, now called periodane.
His ground-state isomer proposal has recently been refined by Bera et al. using
DFT. Here, we take the approach of molecules in such a cluster as starting
point. We first study therefore the triangular molecule LiOB by coupled cluster
theory (CCSD) and thereby specify accurately its equilibrium geometry in free
space. The second fragment we consider is FBeCN, but treated now by restricted
Hartree-Fock (RHF) theory. This four-center species is found to be linear, and
the bond lengths are obtained from both RHF and CCSD calculations. Finally, we
bring these two entities together and find that while LiOB remains largely
intact, FBeCN becomes bent by the interaction with LiOB. Hartree-Fock and CCSD
theories then predict precisely the same lowest isomer found by Bera et al.
solely on the basis of DFT.


title:
Center manifold and multivariable approximants applied to non-linear
  stability analysis

abstract:
  This paper presents a research devoted to the study of instability phenomena
in non-linear model with a constant brake friction coefficient. This paper
outlines the stability analysis and a procedure to reduce and simplify the
non-linear system, in order to obtain limit cycle amplitudes. The center
manifold approach, the multivariable approximants theory, and the alternate
frequency/time domain (AFT) method are applied. Brake vibrations, and more
specifically heavy trucks grabbing are concerned. The modelling introduces
sprag-slip mechanism based on dynamic coupling due to buttressing. The
non-linearity is expressed as a polynomial with quadratic and cubic terms. This
model does not require the use of brake negative coefficient, in order to
predict the instability phenomena. Finally, the center manifold approach, the
multivariable approximants, and the AFT method are used in order to obtain
equations for the limit cycle amplitudes. These methods allow the reduction of
the number of equations of the original system in order to obtain a simplified
system, without loosing the dynamics of the original system, as well as the
contributions of non-linear terms. The goal is the validation of this procedure
for a complex non-linear model by comparing results obtained by solving the
full system and by using these methods. The brake friction coefficient is used
as an unfolding parameter of the fundamental Hopf bifurcation point.


title: Population of HMXB in the Galaxy

abstract:
  We study populations of High-Mass X-ray Binaries in the Galaxy using data of
the INTEGRAL observatory in a hard X-ray energy band. More than two hundreds of
sources were detected with INTEGRAL near the galactic plane (|b|<5 deg), most
of them have a galactic origin and belong to high (HMXB) and low mass (LMXB)
X-ray binaries. We investigated properties and spectra of a large sample of
HMXBs and concluded that most of them are belong to X-ray pulsars. We also
build the distribution of HMXBs for the whole Galaxy and showed that its peaks
are practically coincident with spiral arm tangents. The obtained results are
discussed in terms of some model estimations of the density of different
components of the Galaxy.


title:
Charged rho meson production in neutrino-induced reactions at E_nu = 10
  GeV

abstract:
  The neutrinoproduction of charged $\rho$ mesons on nuclei and nucleons is
investigated for the first time at moderate energies ($<E_\nu > \approx$ 10
GeV), using the date obtained with SKAT bubble chamber. No strong nuclear
effects are observed in $\rho^+$ and $\rho^-$ production. The fractions of
charged and neutral pions originating from $\rho$ decays are obtained and
compared with higher energy data. From analysis of the obtained and available
data on $\rho^+$ and $K^{*+}$(892) neutrinoproduction, the strangeness
suppression factor in the quark string fragmentation is extracted: $\lambda_s =
0.18\pm0.03$. Estimations are obtained for cross sections of quasiexclusive
single $\rho^+$ and coherent $\rho^+$ neutrinoproduction on nuclei. The
estimated coherent cross section $\sigma_{\rho^+}^{coh}$ = (0.29$\pm0.16)\cdot
10^{-38}$ cm$^2$ is compatible with theoretical predictions.


title: First optical detection from the supernova remnant G 15.1-1.6

abstract:
  Deep optical CCD images of the supernova remnant G 15.1-1.6 were obtained and
filamentary and diffuse emission has been discovered. The images, taken in the
emission lines of Halpha+[N II], [S II] and [O III], reveal filamentary and
diffuse structures all around the remnant. The radio emission at 4850 MHz in
the same area is found to be well correlated with the brightest optical
filaments. The IRAS 60 micron emission may also be correlated with the optical
emission but to a lesser extent. The flux calibrated images suggest that the
optical emission originates from shock-heated gas ([S II]/Halpha > 0.4), while
there is a possible HII region ([S II]/Halpha ~0.3) contaminating the supernova
remnant's emission to the east. Furthermore, deep long-slit spectra were taken
at two bright filaments and also show that the emission originates from shock
heated gas. An [O III] filamentary structure has also been detected further to
the west but it lies outside the remnant's boundaries and possibly is not
associated to it. The [O III] flux suggests shock velocities into the
interstellar "clouds" ~100 km/s, while the [S II] 6716/6731 ratio indicates
electron densities up to ~250 cm^{-3}. Finally, the Halpha emission has been
measured to be between 2 to 7 x 10^{-16} erg/s/cm^2/arcsec^2, while the lower
limit to the distance is estimated at 2.2 kpc.


title: Detecting rigid convexity of bivariate polynomials

abstract:
  Given a polynomial $x \in {\mathbb R}^n \mapsto p(x)$ in $n=2$ variables, a
symbolic-numerical algorithm is first described for detecting whether the
connected component of the plane sublevel set ${\mathcal P} = \{x : p(x) \geq
0\}$ containing the origin is rigidly convex, or equivalently, whether it has a
linear matrix inequality (LMI) representation, or equivalently, if polynomial
$p(x)$ is hyperbolic with respect to the origin. The problem boils down to
checking whether a univariate polynomial matrix is positive semidefinite, an
optimization problem that can be solved with eigenvalue decomposition. When the
variety ${\mathcal C} = \{x : p(x) = 0\}$ is an algebraic curve of genus zero,
a second algorithm based on B\'ezoutians is proposed to detect whether
$\mathcal P$ has an LMI representation and to build such a representation from
a rational parametrization of $\mathcal C$. Finally, some extensions to
positive genus curves and to the case $n>2$ are mentioned.


title:
Central exclusive diffractive Higgs boson production in hadron-nucleus
  and nucleus-nucleus collisions at the LHC

abstract:
  In this paper, it is shown that in hadron-nucleus and nucleus-nucleus
collisions, the main source for central exclusive diffractive Higgs production
is photon-photon fusion. At the LHC energy, the total cross section for this
process is about 0.6 pb (for proton-gold scattering), and 3.9 nb (for gold-gold
collision) while the gluon-gluon fusion leads to the value of the cross section
for CED Higgs production which is about 0.1 nb and 3.9 pb respectively.


title:
Interface energies of (100)_{YSZ} and (111)_{YSZ} epitaxial islands on
  (0001)_{alpha-Al_2O_3} substrates from first principles

abstract:
  We present an ab initio study of the interface energies of cubic
yttria-stabilized zirconia (YSZ) epitaxial layers on a (0001)_{alpha-Al_2O_3}
substrate. The interfaces are modelled using a supercell geometry and the
calculations are carried out in the framework of density-functional theory
(DFT) and the local-density approximation (LDA) using the
projector-augmented-wave (PAW) pseudopotential approach. Our calculations
clearly demonstrate that the (111)_{YSZ} || (0001)_{alpha-Al_2O_3} interface
energy is lower than that of (100)_{YSZ} || (0001)_{alpha-Al_2O_3}. This result
is central to understanding the behaviour of YSZ thin solid film islanding on
(0001)_{alpha-Al_2O_3} substrates, either flat or in presence of defects.


title:
A survey for low mass spectroscopic binary stars in the young clusters
  around sigma Orionis and lambda Orionis

abstract:
  We have obtained multi-epoch, high-resolution spectroscopy of 218 candidate
low-mass stars and brown dwarfs in the young clusters around sigma Ori and
lambda Ori. We find that 196 targets are cluster members based on their radial
velocity, the equivalent width of their NaI 8200 lines and the spectral type
from their TiO band strength. We have identified 11 new binary stars among the
cluster members based on their variable radial velocity and an additional
binary from the variation in its line width and shape. The sample covers the
magnitude range Ic=14-18.9 (mass =~ 0.55-0.03 Msun), but all of the binary
stars are brighter than Ic=16.6 (mass =~ 0.12Msun) and 10 are brighter than
Ic=15.5 (mass =~ 0.23Msun). There is a significant lack of spectroscopic
binaries in our sample at faint magnitudes even when we account for the
decrease in sensitivity with increasing magnitude. We can reject the hypothesis
that the fraction of spectroscopic binaries is a uniform function of Ic
magnitude with more than 99% confidence. The spectroscopic binary fraction for
stars more massive than about 0.1Msun (Ic < 16.9) is
f_bright=0.095(+0.012)(-0.028). The 90% confidence upper limit to the
spectroscopic binary fraction for very low mass (VLM) stars (mass < 0.1Msun)
and brown dwarfs (BDs) is f_faint < 7.5%. The hypothesis that f_bright and
f_faint are equal can be rejected with 90% confidence. We conclude that we have
found strong evidence for a change in the fraction of spectroscopic binaries
among young VLM stars and brown dwarfs when compared to more massive stars in
the same star-forming region. This implies a difference in the total binary
fraction between VLM stars and BDs compared to more massive stars or a
difference in the distribution of semi-major axes, or both. (Abridged)


title: Predictions from an anisotropic inflationary era

abstract:
  This article investigates the predictions of an inflationary phase starting
from a homogeneous and anisotropic universe of the Bianchi I type. After
discussing the evolution of the background spacetime, focusing on the number of
e-folds and the isotropization, we solve the perturbation equations and predict
the power spectra of the curvature perturbations and gravity waves at the end
of inflation. The main features of the early anisotropic phase is (1) a
dependence of the spectra on the direction of the modes, (2) a coupling between
curvature perturbations and gravity waves, and (3) the fact that the two
gravity waves polarisations do not share the same spectrum on large scales. All
these effects are significant only on large scales and die out on small scales
where isotropy is recovered. They depend on a characteristic scale that can,
but a priori must not, be tuned to some observable scale. To fix the initial
conditions, we propose a procedure that generalises the one standardly used in
inflation but that takes into account the fact that the WKB regime is violated
at early times when the shear dominates. We stress that there exist modes that
do not satisfy the WKB condition during the shear-dominated regime and for
which the amplitude at the end of inflation depends on unknown initial
conditions. On such scales, inflation loses its predictability. This study
paves the way to the determination of the cosmological signature of a
primordial shear, whatever the Bianchi I spacetime. It thus stresses the
importance of the WKB regime to draw inflationary predictions and demonstrates
that when the number of e-folds is large enough, the predictions converge
toward those of inflation in a Friedmann-Lemaitre spacetime but that they are
less robust in the case of an inflationary era with a small number of e-folds.


title: K-duality for stratified pseudomanifolds

abstract:
  This paper is devoted to the study of Poincar\'e duality in K-theory for
general stratified pseudomanifolds. We review the axiomatic definition of a
smooth stratification $\fS$ of a topological space $X$ and we define a groupoid
$T^{\fS}X$, called the $\fS$-tangent space. This groupoid is made of different
pieces encoding the tangent spaces of the strata, and these pieces are glued
into the smooth noncommutative groupoid $T^{\fS}X$ using the familiar procedure
introduced by A. Connes for the tangent groupoid of a manifold. The main result
is that $C^{*}(T^{\fS}X)$ is Poincar\'e dual to $C(X)$, in other words, the
$\fS$-tangent space plays the role in $K$-theory of a tangent space for $X$.


title: Interfacial roughening in field theory

abstract:
  In the rough phase, the width of interfaces separating different phases of
statistical systems increases logarithmically with the system size. This
phenomenon is commonly described in terms of the capillary wave model, which
deals with fluctuating, infinitely thin membranes, requiring ad hoc cut-offs in
momentum space. We investigate the interface roughening from first principles
in the framework of the Landau-Ginzburg model, that is renormalized field
theory, in the one-loop approximation. The interface profile and width are
calculated analytically, resulting in finite expressions with definite
coefficients. They are valid in the scaling region and depend on the known
renormalized coupling constant.


title:
Confirmation of a correlation between the X-ray luminosity and spectral
  slope of AGNs in the Chandra Deep Fields

abstract:
  We present results from a statistical analysis of 173 bright radio-quiet AGNs
selected from the Chandra Deep Field-North and Chandra Deep Field-South surveys
(hereafter, CDFs) in the redshift range of 0.1 < z < 4. We find that the X-ray
power-law photon index (Gamma) of radio-quiet AGNs is correlated with their
2-10 keV rest-frame X-ray luminosity (L_X) at the > 99.5 percent confidence
level in two redshift bins, 0.3 < z < 0.96, and 1.5 < z < 3.3 and is slightly
less significant in the redshift bin 0.96 < z < 1.5. We investigate the
redshift evolution of the correlation between the power-law photon index and
the hard X-ray luminosity and find that the slope and offset of a linear fit to
the correlation change significantly (at the > 99.9 percent confidence level)
between redshift bins of 0.3 < z < 0.96 and 1.5 < z < 3.3. We explore physical
scenarios explaining the origin of this correlation and its possible evolution
with redshift in the context of steady corona models focusing on its dependency
on variations of the properties of the hot corona with redshift.


title: ACM bundles on cubic surfaces

abstract:
  In this paper we prove that, for every $r \geq 2$, the moduli space
$M^s_X(r;c_1,c_2)$ of rank $r$ stable vector bundles with Chern classes
$c_1=rH$ and $c_2=(3r^2-r)/2$ on a nonsingular cubic surface $X \subset
\mathbb{P}^3$ contains a nonempty smooth open subset formed by ACM bundles,
i.e. vector bundles with no intermediate cohomology. The bundles we consider
for this study are extremal for the number of generators of the corresponding
module (these are known as Ulrich bundles), so we also prove the existence of
indecomposable Ulrich bundles of arbitrarily high rank on $X$.


title: Evaporative attachment of slow electrons to alkali nanoclusters

abstract:
  The abundance spectrum of Na^-_{n~7-140} anions formed by low energy electron
attachment to free nanoclusters is measured to be strongly and nontrivially
restructured with respect to the neutral precursor beam. This restructuring is
explained in quantitative detail by a general framework of evaporative
attachment: an electron is captured by the long-range polarization potential,
its energy is transferred into thermal vibrations, and dissipated by
evaporative cooling. The data also affirm a formulated relation between the
binding energies of cationic, neutral, and anionic clusters, and an adjustment
to the prior values of dimer evaporation energies.


title:
Multimode vibrational effects in single molecule conductance: A
  nonequilibrium Green's function approach

abstract:
  The role of multimode vibrational dynamics in electron transport through
single molecule junctions is investigated. The study is based on a generic
model, which describes charge transport through a single molecule that is
attached to metal leads. To address vibrationally-coupled electron transport,
we employ a nonequilibrium Green's function approach that extends a method
recently proposed by Galperin et al. [Phys. Rev. B 73, 045314 (2006)] to
multiple vibrational modes. The methodology is applied to two systems: a
generic model with two vibrational degrees of freedom and
benzenedibutanethiolate covalently bound to gold electrodes. The results show
that the coupling to multiple vibrational modes can have a significant effect
on the conductance of a molecular junction. In particular, we demonstrate the
effect of electronically induced coupling between different vibrational modes
and study nonequilibrium vibrational effects by calculating the current-induced
excitation of vibrational modes.


title: Influence of spin and interactions on quantum dots and nano-wires

abstract:
  In this dissertation we use sophisticated numerical methods in order to
examine ground-state (GS) properties of two types of quantum systems with
electron electron interactions: A quantum dot (QD) and a nano-wire. In the
first half of the work we study a system of a single level coupled to a
one-dimensional wire with interacting spinless electrons, when the wire is
either clean or disordered. We utilize the density-matrix renormalization-group
(DMRG) method to investigate the influence of the level on several
thermodynamic properties of the clean interacting wire, which can be in one of
two phases: Tomonaga-Luttinger liquid and charge density wave phases. When the
wire is disordered, we investigate the Friedel oscillations, exploring the
difference between the two phases and comparing them to the clean
non-interacting case, for which we develop an exact formula for the
oscillations. In the second half of the dissertation we study two cases of an
isolated two-dimensional QD. We begin by an investigation of a new numerical
method, the particle-hole DMRG (PH-DMRG), which is used to calculate the GS
energy of a disordered QD consisting of interacting spinless electrons. We show
that this method is much more accurate than the Hartree-Fock method, and we
suggest an improvement of the algorithm, which reduces the error rate by almost
30 percents. Finally we study the magnetization of a QD with spin 1/2
electrons, in the presence of spin-orbit coupling and interactions. We
calculate the g-factor and the expectation values of the spin operators in the
GS, and find that when the QD is occupied by an even number of electrons, the
GS can have a finite magnetization.


title:
Characterization of strong light-matter coupling in semiconductor
  quantum-dot microcavities via photon-statistics spectroscopy

abstract:
  It is shown that spectrally resolved photon-statistics measurements of the
resonance fluorescence from realistic semiconductor quantum-dot systems allow
for high contrast identification of the two-photon strong-coupling states.
Using a microscopic theory, the second-rung resonance is analyzed and optimum
excitation conditions are determined. The computed photon-statistics spectrum
displays gigantic, experimentally robust resonances at the energetic positions
of the second-rung emission.


title: Escaping points of entire functions of small growth

abstract:
  Let $f$ be a transcendental entire function and let $I(f)$ denote the set of
points that escape to infinity under iteration. We give conditions which ensure
that, for certain functions, $I(f)$ is connected. In particular, we show that
$I(f)$ is connected if $f$ has order zero and sufficiently small growth or has
order less than 1/2 and regular growth. This shows that, for these functions,
Eremenko's conjecture that $I(f)$ has no bounded components is true. We also
give a new criterion related to $I(f)$ which is sufficient to ensure that $f$
has no unbounded Fatou components.


title: Baryonic Tully-Fisher Relation for Extremely Low Mass Galaxies

abstract:
  We study Tully-Fisher relations for a sample that combines extremely faint
(M_B > -14.0) galaxies along with bright (i.e. L_*) galaxies. Accurate (~ 10%)
distances, I band photometry, and B-V colors are known for the majority of the
galaxies in our sample. The faint galaxies are drawn from the Faint Irregular
Galaxy GMRT survey (FIGGS), and we have HI rotation velocities derived from
aperture synthesis observations for all of them. For the faint galaxies, we
find that even though the median HI and stellar masses are comparable, the HI
mass correlates significantly better with the circular velocity indicators than
the stellar mass. We also find that W$_{20}$ correlates better with mass than
the rotation velocity, although the difference is not statistically
significant. The faint galaxies lie systematically below the I band TF relation
defined by bright galaxies, and also show significantly more intrinsic scatter.
This implies that the integrated star formation in these galaxies has been both
less efficient and also less regulated than in large galaxies. We find that
while the faint end deviation is greatly reduced in Baryonic Tully-Fisher (BTF)
relations, the existence of a break at the faint end of the BTF is subject to
systematics such as the assumed stellar mass to light ratio. If we assume that
there is an intrinsic BTF and try to determine the baryonic mass by searching
for prescriptions that lead to the tightest BTF, we find that scaling the HI
mass leads to a much more significant tightening than scaling the stellar mass
to light ratio. The most significant tightening that we find however, is if we
scale the entire baryonic mass of the faint (but not the bright) galaxies. Such
a scenario would be consistent with models where dwarf (but not large) galaxies
have a large fraction of dark or ``missing'' baryons (Slightly abridged)


title:
Fermiology of Cuprates from First Principles: From Small Pockets to the
  Luttinger Fermi surface

abstract:
  Fermiology, the shape and size of the Fermi surface, underpins the
low-temperature physical properties of a metal. Recent investigations of the
Fermi surface of high-Tc superconductors, however, show a most unusual
behavior: upon addition of carriers, ``Fermi'' pockets appear around nodal
(hole doping) and antinodal (electron doping) regions of the Brillouin zone in
the ``pseudogap'' state. With progressive doping, p, these evolve into
well-defined Fermi surfaces around optimal doping (p_opt), with no pseudogap.
Correspondingly, various physical responses, including d-wave
superconductivity, evolve from highly anomalous, up to p_opt, to more
conventional beyond. Describing this evolution holds the key to understanding
high-temperature superconductivity. Here, we present ab initio quantum chemical
results for cuprates, providing a quantitative description of the evolution of
the Fermi surface with doping. Our results constitute an ab initio
justification for several, hitherto proposed semiphenomenological theories,
offering an unified basis for understanding of various, unusual physical
responses of doped cuprates.


title:
Spectrum of Andreev Bound States in a Molecule Embedded Inside a
  Microwave-Excited Superconducting Junction

abstract:
  Non-dissipative Josephson current through nanoscale superconducting
constrictions is carried by spectroscopically sharp energy states, so-called
Andreev bound states. Although theoretically predicted almost 40 years ago, no
direct spectroscopic evidence of these Andreev bound states exists to date. We
propose a novel type of spectroscopy based on embedding a superconducting
constriction, formed by a single-level molecule junction, in a microwave QED
cavity environment. In the electron-dressed cavity spectrum we find a polariton
excitation at twice the Andreev bound state energy, and a superconducting-phase
dependent ac Stark shift of the cavity frequency. Dispersive measurement of
this frequency shift can be used for Andreev bound state spectroscopy.


title: Detection of diffuse interstellar bands in M31

abstract:
  We investigate the diffuse interstellar band (DIB) spectrum in the
interstellar medium of M31. The DEIMOS spectrograph of the W. M. Keck
observatory was used to make optical spectroscopic observations of two
supergiant stars, MAG 63885 and MAG 70817, in the vicinity of the OB78
association in M31 where the metallicity is approximately equal to solar. The
5780, 5797, 6203, 6283 and 6613 DIBs are detected in both sightlines at
velocities matching the M31 interstellar Na I absorption. The spectra are
classified and interstellar reddenings are derived for both stars. Diffuse
interstellar band (DIB) equivalent widths and radial velocities are presented.
The spectrum of DIBs observed in M31 towards MAG 63885 is found to be similar
to that observed in the Milky Way. Towards MAG 70817 the DIB equivalent widths
per unit reddening are about three times the Galactic average. Compared to
observations elsewhere in the Universe, relative to reddening the M31 ISM in
the vicinity of OB78 is apparently a highly favourable environment for the
formation of DIB carriers.


title: Functions of small growth with no unbounded Fatou components

abstract:
  We prove a form of the $\cos \pi \rho$ theorem which gives strong estimates
for the minimum modulus of a transcendental entire function of order zero. We
also prove a generalisation of a result of Hinkkanen that gives a sufficient
condition for a transcendental entire function to have no unbounded Fatou
components. These two results enable us to show that there is a large class of
entire functions of order zero which have no unbounded Fatou components. On the
other hand we give examples which show that there are in fact functions of
order zero which not only fail to satisfy Hinkkanen's condition but also fail
to satisfy our more general condition. We also give a new regularity condition
that is sufficient to ensure that a transcendental entire function of order
less than 1/2 has no unbounded Fatou components. Finally, we observe that all
the conditions given here which guarantee that a transcendental entire function
has no unbounded Fatou components, also guarantee that the escaping set is
connected, thus answering a question of Eremenko for such functions.


title:
The Boundary Conditions for Point Transformed Electromagnetic
  Invisibility Cloaks

abstract:
  In this paper we study point transformed electromagnetic invisibility cloaks
in transformation media that are obtained by transformation from general
anisotropic media. We assume that there are several cloaks located in different
points in space. Our results apply in particular to the first order
invisibility cloaks introduced by Pendry et al. and to the high order
invisibility cloaks introduced by Hendi et al. and by Cai et al.. We identify
the appropriate {\it cloaking boundary conditions} that the solutions of
Maxwell equations have to satisfy at the outside, $\partial K_+$, and at the
inside, $\partial K_-$, of the boundary of the cloaked object $K$. Namely, that
the tangential components of the electric and the magnetic fields have to
vanish at $\partial K_+$ -what is always true- and that the normal components
of the curl of the electric and the magnetic fields have to vanish at $\partial
K_-$. These results are proven requiring that energy be conserved. In the case
of one spherical cloak with a spherically stratified $K$ and a radial current
at $\partial K$ we verify by an explicit calculation that our {\it cloaking
boundary conditions} are satisfied and that cloaking of active devices holds
even if the current is at the boundary of the cloaked object. As we prove our
results for media that are obtained by transformation from general anisotropic
media, our results apply to the cloaking of objects with active and passive
devices contained in general anisotropic media, in particular to objects with
active and passive devices contained inside general crystals.


title:
Time-dependent Nonlinear Optical Susceptibility of an Out-of-Equilibrium
  Soft Material

abstract:
  We investigate the time-dependent nonlinear optical absorption of a clay
dispersion (Laponite) in organic dye (Rhodamine B) water solution displaying
liquid-arrested state transition. Specifically, we determine the characteristic
time $\tau_D$ of the nonlinear susceptibility build-up due as to the Soret
effect. By comparing $\tau_D$ with the relaxation time provided by standard
dynamic light scattering measurements we report on the decoupling of the two
collective diffusion times at the two very different length scales during the
aging of the out-of-equilibrium system. With this demonstration experiment we
also show the potentiality of nonlinear optics measurements in the study of the
late stage of arrest in soft materials.


title: Dynamic nuclear polarization using a single pair of electrons

abstract:
  We observe dynamic nuclear polarization in a GaAs double dot system using two
electrons that are never exchanged with the reservoir. By periodically bringing
the system to the mixing point where the singlet and the triplet T+ states are
degenerate, we observe that an excess polarization is built up. Surprisingly,
the pumping procedure is most effective when the total duty cycle equals a
multiple of the Larmor precession time of the Ga and As nuclei. The induced
polarization corresponds to cooling of the underlying nuclear system. The
dependence on the dwell time at the mixing point is found to be non-monotonic.


title: Tracing shocks and photodissociation in the Galactic center region

abstract:
  We present a systematic study of the HNCO, C18O, 13CS, and C34S emission
towards 13 selected molecular clouds in the Galactic center region. The
molecular emission in these positions are used as templates of the different
physical and chemical processes claimed to be dominant in the circumnuclear
molecular gas of galaxies. The relative abundance of HNCO shows a variation of
more than a factor of 20 amo ng the observed sources. The HNCO/13CS abundance
ratio is highly contrasted (up to a factor of 30) between the shielded
molecular clouds mostly affected by shocks, where HNCO is released to gas-phase
from grain mantles, and those pervaded by an intense UV radiation field, where
HNCO is photo-dissociated and CS production favored via ion reactions. We
propose the relative HNCO to CS abundance ratio as a highly contrasted
diagnostic tool to distinguish between the influence of shocks and/or the
radiation field in the nuclear regions of galaxies and their relation to the
evolutionary state of their nuclear star formation bursts.


title:
Tunnel effect for Kramers-Fokker-Planck type operators: return to
  equilibrium and applications

abstract:
  In the first part of this work, we consider second order supersymmetric
differential operators in the semiclassical limit, including the
Kramers-Fokker-Planck operator, such that the exponent of the associated
Maxwellian $\phi$ is a Morse function with two local minima and one saddle
point. Under suitable additional assumptions of dynamical nature, we establish
the long time convergence to the equilibrium for the associated heat semigroup,
with the rate given by the first non-vanishing, exponentially small,
eigenvalue. In the second part of the paper, we consider the case when the
function $\phi$ has precisely one local minimum and one saddle point. We also
discuss further examples of supersymmetric operators, including the Witten
Laplacian and the infinitesimal generator for the time evolution of a chain of
classical anharmonic oscillators.


title: The QCD critical end point in the PNJL model

abstract:
  We investigate the role played by the Polyakov loop in the dynamics of the
chiral phase transition in the framework of the so-called PNJL model in the
SU(2)sector. We present the phase diagram where the inclusion of the Polyakov
loop moves the critical points to higher temperatures, compared with the NJL
model results. The critical properties of physical observables, such as the
baryon number susceptibility and the specific heat, are analyzed in the
vicinity of the critical end point, with special focus on their critical
exponents. The results with the PNJL model are closer to lattice results and we
also recover the universal behavior of the critical exponents of both the
baryon susceptibility and the specific heat.


title: Index theory and Groupoids

abstract:
  This paper collects the notes of a serie of lectures given by the two authors
during the summer school "Geometric and topological methods for Quantum Field
Theory" at Villa de Leyva, Colombia, summer 2007. These lecture notes are
mainly devoted to a proof using groupoids and $KK$-theory of Atiyah-Singer
index theorem on compact smooth manifolds. We will present an elementary
introduction to groupoids, $C^*$-algebras, $KK$-theory and pseudodifferential
calculus on groupoids. We will finish by showing that the point of view adopted
here generalizes to the case of conical pseudo-manifolds.


title:
On the role of heavy flavor parton distributions at high energy
  colliders

abstract:
  We compare `fixed flavor number scheme' (FFNS) and `variable flavor number
scheme' (VFNS) parton model predictions at high energy colliders. Based on our
recent LO- and NLO-FFNS dynamical parton distributions, we generate radiatively
two sets of VFNS parton distributions where also the heavy quark flavors
h=c,b,t are considered as massless partons within the nucleon. By studying the
role of these distributions in the production of heavy particles (h\bar{h},
t\bar{b}, hW^{+-}, Higgs--bosons, etc.) at high energy ep, p\bar{p} and pp
colliders, we show that the VFNS predictions are compatible with the FFNS ones
(to within about 10-20% at LHC, depending on the process) when the invariant
mass of the produced system far exceeds the mass of the participating heavy
quark flavor.


title:
Comparison between models of insulator and semiconductor thin films
  islanding

abstract:
  The synthesis of self-organized quantum dots (QD's) can be achieved through
bottom up layer by layer deposition processes as chemical vapor deposition
(CVD) or physical vapor deposition (PVD). However, QD's may also be synthesized
via sol-gel route, which involves a spontaneous evolution from thin films to
discrete QD's without further deposition. The aim of the paper is to discuss
and compare the physical phenomena involved in QD's formation which initiate
from thin film surface roughening between PVD-CVD and sol-gel synthesis
approaches. We propose two simple physical models which are relevant to explain
the fundamental differences between those methods.


title:
High-fidelity transmission of polarization encoded qubits from an
  entangled source over 100 km of fiber

abstract:
  We demonstrate non-degenerate down-conversion at 810 and 1550 nm for
long-distance fiber based quantum communication using polarization entangled
photon pairs. Measurements of the two-photon visibility, without dark count
subtraction, have shown that the quantum correlations (raw visibility 89%)
allow secure quantum cryptography after 100 km of non-zero dispersion shifted
fiber using commercially available single photon detectors. In addition,
quantum state tomography has revealed little degradation of state negativity,
decreasing from 0.99 at the source to 0.93 after 100 km, indicating minimal
loss in fidelity during the transmission.


title: The Spin-Statistics Theorem for Anyons and Plektons in d=2+1

abstract:
  We prove the spin-statistics theorem for massive particles obeying braid
group statistics in three-dimensional Minkowski space. We start from first
principles of local relativistic quantum theory. The only assumption is a gap
in the mass spectrum of the corresponding charged sector, and a restriction on
the degeneracy of the corresponding mass.


title:
What Prevents Internal Gravity Waves From Disturbing the Solar Uniform
  Rotation?

abstract:
  Internal gravity waves (IGWs) are naturally produced by convection in stellar
envelopes, and they could be an important mechanism for transporting angular
momentum in the radiative interiors of stars. Prior work has established that
they could operate over a short enough time scale to explain the internal solar
rotation as a function of depth. We demonstrate that the natural action of IGWs
is to produce large scale oscillations in the solar rotation as a function of
depth, which is in marked contrast to the nearly uniform rotation in the outer
radiative envelope of the Sun. An additional angular momentum transport
mechanism is therefore required, and neither molecular nor shear-induced
turbulent viscosity is sufficient to smooth out the profile. Magnetic
processes, such as the Tayler-Spruit dynamo, could flatten the rotation
profile. We therefore conclude that IGWs must operate in conjunction with
magnetic angular momentum transport processes if they operate at all.
Furthermore, both classes of mechanisms must be inhibited to some degree by
mean molecular weight gradients in order to explain the recent evidence for a
rapidly rotating embedded core in the Sun.


title:
Erratum to Measurement of $\sigma (p \bar p \to Z) \cdot Br(Z \to
  \tau\tau)$ at $\bm{\sqrt{s}=}$1.96 TeV, published in Phys. Rev. D {71},
  072004 (2005)

abstract:
  A change in estimated integrated luminosity (from 226 pb$^{-1} to 257
pb$^{-1}$ leads to a corrected value for ${\sigma (p \bar p \to Z)
\cdot}$Br${(Z \to \tau \tau)}$ of $209\pm13(stat.)\pm16(syst.)\pm13(lum) pb.


title: Multiparty Communication Complexity of Disjointness

abstract:
  We obtain a lower bound of n^Omega(1) on the k-party randomized communication
complexity of the Disjointness function in the `Number on the Forehead' model
of multiparty communication when k is a constant. For k=o(loglog n), the bounds
remain super-polylogarithmic i.e. (log n)^omega(1). The previous best lower
bound for three players until recently was Omega(log n).
  Our bound separates the communication complexity classes NP^{CC}_k and
BPP^{CC}_k for k=o(loglog n). Furthermore, by the results of Beame, Pitassi and
Segerlind \cite{BPS07}, our bound implies proof size lower bounds for
tree-like, degree k-1 threshold systems and superpolynomial size lower bounds
for Lovasz-Schrijver proofs.
  Sherstov \cite{She07b} recently developed a novel technique to obtain lower
bounds on two-party communication using the approximate polynomial degree of
boolean functions. We obtain our results by extending his technique to the
multi-party setting using ideas from Chattopadhyay \cite{Cha07}.
  A similar bound for Disjointness has been recently and independently obtained
by Lee and Shraibman.


title:
On the construction of model Hamiltonians for adiabatic quantum
  computation and its application to finding low energy conformations of
  lattice protein models

abstract:
  In this report, we explore the use of a quantum optimization algorithm for
obtaining low energy conformations of protein models. We discuss mappings
between protein models and optimization variables, which are in turn mapped to
a system of coupled quantum bits. General strategies are given for constructing
Hamiltonians to be used to solve optimization problems of
physical/chemical/biological interest via quantum computation by adiabatic
evolution. As an example, we implement the Hamiltonian corresponding to the
Hydrophobic-Polar (HP) model for protein folding. Furthermore, we present an
approach to reduce the resulting Hamiltonian to two-body terms gearing towards
an experimental realization.


title: Toric complexes and Artin kernels

abstract:
  A simplicial complex L on n vertices determines a subcomplex T_L of the
n-torus, with fundamental group the right-angled Artin group G_L. Given an
epimorphism \chi\colon G_L\to \Z, let T_L^\chi be the corresponding cover, with
fundamental group the Artin kernel N_\chi. We compute the cohomology jumping
loci of the toric complex T_L, as well as the homology groups of T_L^\chi with
coefficients in a field \k, viewed as modules over the group algebra \k\Z. We
give combinatorial conditions for H_{\le r}(T_L^\chi;\k) to have trivial
\Z-action, allowing us to compute the truncated cohomology ring, H^{\le
r}(T_L^\chi;\k). We also determine several Lie algebras associated to Artin
kernels, under certain triviality assumptions on the monodromy \Z-action, and
establish the 1-formality of these (not necessarily finitely presentable)
groups.


title: Universal Bounds for SU(3) Low Energy Constants

abstract:
  In this paper bounds for L_1, L_2 and L_3 are obtained in Chiral Perturbation
Theory with three flavours. At the same time we test the compatibility of this
theory with axiomatic principles. Following a recent paper we use dispersion
relations to write positivity conditions that translate into bounds for the
chiral low energy constants. As a first approach we consider the exact SU(3)_V
limit and notice that if a common mass of the order of that of the kaon is
adopted for the octet of pseudo-Goldstone bosons the bounds have very large
O(p^6) corrections. Once the positivity conditions are adapted to account for
different masses, we correct the previous bounds for a physical kaon mass and
find that they tighten. We observe an overlap between the experimentally
determined region and the first principles forbidden region, in the space of
parameters.


title: Coarse graining of master equations with fast and slow states

abstract:
  We propose a general method for simplifying master equations by eliminating
from the description rapidly evolving states. The physical recipe we impose is
the suppression of these states and a renormalization of the rates of all the
surviving states. In some cases, this decimation procedure can be analytically
carried out and is consistent with other analytical approaches, like in the
problem of the random walk in a double-well potential. We discuss the
application of our method to nontrivial examples: diffusion in a lattice with
defects and a model of an enzymatic reaction outside the steady state regime.


title: Area, capacity and diameter versions of Schwarz's Lemma

abstract:
  The now canonical proof of Schwarz's Lemma appeared in a 1907 paper of
Carath\'eodory, who attributed it to Erhard Schmidt. Since then, Schwarz's
Lemma has acquired considerable fame, with multiple extensions and
generalizations. Much less known is that, in the same year 1907, Landau and
Toeplitz obtained a similar result where the diameter of the image set takes
over the role of the maximum modulus of the function. We give a new proof of
this result and extend it to include bounds on the growth of the maximum
modulus. We also develop a more general approach in which the size of the image
is estimated in several geometric ways via notions of radius, diameter,
perimeter, area, capacity, etc...


title:
Two-component, ideal, self-gravitating fluids: the fractional virial
  potential energy

abstract:
  Two-component, ideal, self-gravitating fluids are conceived as macrogases,
and the related equation of state is expressed using the virial theorem for
subsystems, under the restriction of homeoidally striated density profiles.
Shallower density profiles are found to yield an equation of state,
\phi=\phi(y,m), characterized (for assigned values of the fractional mass,
m=M_j/ M_i) by the occurrence of two extremum points, a minimum and a maximum.
Steeper density profiles produce a similar equation of state, which implies
that a special value of m is related to a critical curve where the above
mentioned extremum points reduce to a single horizontal inflexion point, and
curves below the critical one show no extremum points. The similarity of the
isofractional mass curves to van der Waals' isothermal curves, suggests the
possibility of a phase transition in a bell-shaped region of the (O y \phi)
plane, where the fractional truncation radius along a selected direction is
y=R_j/R_i, and the fractional virial potential energy is
\phi=(E_{ji})_{vir}/(E_{ij})_{vir}. Further investigation is devoted to mass
distributions described by Hernquist (1990) density profiles, for which an
additional relation can be used to represent a sample of N=16 elliptical
galaxies (EGs) on the (O y \phi) plane, under the assumption that the
fractional mass related to EGs and their hosting dark matter (DM) haloes, has a
universal value. In the light of the model, the evolution of isolated EGs
appears to be other than strictly homologous, due to different values of
fractional truncation radii, y, or fractional scaling radii, y^\dagger, deduced
from sample objects.


title:
Anderson localization of a Bose-Einstein condensate in a 3D random
  potential

abstract:
  We study the effect of Anderson localization on the expansion of a
Bose-Einstein condensate, released from a harmonic trap, in a 3D random
potential. We use scaling arguments and the self-consistent theory of
localization to show that the long-time behavior of the condensate density is
controlled by a single parameter equal to the ratio of the mobility edge and
the chemical potential of the condensate. We find that the two critical
exponents of the localization transition determine the evolution of the
condensate density in time and space.


title: Killing Vector Fields, Maxwell Equations and Lorentzian Spacetimes

abstract:
  In this paper we first analyze the structure of Maxwell equations in a
Lorentzian spacetime where the potential A is proportional to 1-form K
physically equivalent to a Killing vector field (supposed to exist). We show
that such A obeys the Lorenz gauge and also a wave equation that can be written
in terms of the covariant D'Alembertian or the Ricci operator. Moreover, we
determine the correct current defined by that potential showing that it is of
superconducting type, being two times the product of the components of A by the
Ricci 1-form fields. We also study the structure of the spacetime generated by
the coupled system consisting of a electromagnetic field F = dA (A, as above),
an ideal charged fluid with dynamics described by an action function S and the
gravitational field. We show that Einstein equations in this situation is then
equivalent to Maxwell equations with a current givn by fFAF (the product
meaning the Clifford product of the corresponding form fields), where f is a
scalar function which satisfies a well determined algebraic quadratic equation.


title: On the Representation Theory of an Algebra of Braids and Ties

abstract:
  We consider the algebra ${\cal E}_n(u)$ introduced by F. Aicardi and J.
Juyumaya as an abstraction of the Yokonuma-Hecke algebra. We construct a tensor
space representation for ${\cal E}_n(u)$ and show that this is faithful. We use
it to give a basis for ${\cal E}_n(u)$ and to classify its irreducible
representations.


title: TMT Science and Instruments

abstract:
  To meet the scientific goals of the Thirty Meter Telescope Project, full
diffraction-limited performance is required from the outset and hence the
entire observatory is being designed, as a system, to achieve this. The
preliminary design phases of the telescope and the first light adaptive optic
facility are now approaching completion so that much better predictions of the
system performance are possible. The telescope design and instrumentation are
summarized in this presentation, with a brief description of some of the
scientific programs that are foreseen.


title: X(2175) as a resonant state of the $\phi K \bar{K}$ system

abstract:
  We perform a Faddeev calculation for the three mesons system, $\phi K
\bar{K}$, taking the interaction between two pseudoscalar mesons and between a
vector and a pseudoscalar meson from the chiral unitary approach. We obtain a
neat resonance peak around a total mass of 2150 MeV and an invariant mass for
the $K \bar{K}$ system around 970 MeV, very close to the $f_0(980)$ mass. The
state appears in I=0 and qualifies as a $\phi f_0(980)$ resonance. We enlarge
the space of states including $\phi \pi \pi$, since $\pi \pi$ and $K \bar{K}$
build up the $f_0$ (980), and find moderate changes that serve to quantify
theoretical uncertainties. No state is seen in I=1. This finding provides a
natural explanation for the recent state found at BABAR and BES, the X(2175),
which decays into $\phi f_0(980)$.


title:
Asymptotic cones, bi-Lipschitz ultraflats, and the geometric rank of
  geodesics

abstract:
  Given a geodesic inside a simply-connected, complete, non-positively curved
Riemannian (NPCR) manifold M, we get an associated geodesic inside the
asymptotic cone Cone(M). Under mild hypotheses, we show that if the latter is
contained inside a bi-Lipschitz flat, then the original geodesic supports a
non-trivial, orthogonal, parallel Jacobi field. As applications we obtain (1)
constraints on the behavior of quasi-isometries between complete, simply
connected, NPCR manifolds, and (2) constraints on the NPCR metrics supported by
certain manifolds, and (3) a correspondence between metric splittings of
complete, simply connected NPCR manifolds, and metric splittings of its
asymptotic cones. Furthermore, combining our results with the
Ballmann-Burns-Spatzier rigidity theorem and the classic Mostow rigidity, we
also obtain (4) a new proof of Gromov's rigidity theorem for higher rank
locally symmetric spaces.


title:
Relativistic versus Newtonian orbit model: the Relativistic Motion
  Integrator (RMI) software. Illustration with the LISA mission

abstract:
  The Relativistic Motion Integrator (RMI) consists in integrating numerically
the EXACT relativistic equations of motion, for a given metric (corresponding
to a gravitational field at first post-Newtonian order or higher), instead of
Newtonian equations plus relativistic corrections. The aim of the present paper
is to validate the method, and to illustrate how RMI can be used for space
missions to produce relativistic ephemerides of test-bodies (or satellites).
Indeed, nowadays, relativistic effects have to be taken into account, and
comparing a RMI model with a classical keplerian one helps to quantify such
effects.
  LISA is a relevant example to use RMI. A precise orbit model for the LISA
spacecraft is needed not only for the sake of satellite ephemerides but also to
compute the photon flight time in laser links between spacecraft, required in
LISA data pre-processing in order to reach the gravitational wave detection
level.
  Relativistic effects in LISA orbit model needed to be considered and
quantified. Using RMI, we show that the numerical classical model for LISA
orbits in the gravitational field of a non-rotating spherical Sun without
planets can be wrong, with respect to the numerical relativisitic version of
the same model, by as much as about ten kilometers in radial distance during a
year and up to about 60 kilometers in along track distance after a year... with
consequences on estimated photon flight times.
  We validated RMI numerical results with a 1PN analytical developpement.


title: QU Carinae: a SNeIa progenitor?

abstract:
  Optical spectra obtained in 2006-07 of the nova-like cataclysmic variable QU
Car are studied for radial velocities, line profiles, and line identifications.
We are not able to confirm the reported 10.9 hr orbital period from 1982,partly
because our sampling is not ideal for this purpose and also, we suspect,
because our radial velocities are distorted by line profile changes due to an
erratic wind. P-Cygni profiles are found in several of the emission lines,
including those of C IV. Carbon lines are abundant in the spectra, suggesting a
carbon enrichment in the doner star. The presence of [O III] 5007\AA and [N II]
6584\AA is likely due to a diffuse nebula in the vicinity of the system.
  The wind signatures in the spectra and the presence of nebular lines are in
agreement with the accretion wind evolution scenario that has been suggested to
lead to SNeIa. We argue that QU Car is a member of the V Sge subclass of CVs,
and a possible SNeIa progenitor. It is shown that the recent light curve of QU
Car has ~1 mag low states, similar to the light curve of V Sge, strengthening
the connection of QU Car with V Sge stars, supersoft x-ray sources, and SNeIa
progenitors.


title:
The sum of irreducible fractions with consecutive denominators is never
  an integer in a very weak arithmetic

abstract:
  Two theorems of elmentary arithmetic, one stating that the sum of the
reciprocals of any number of consecutive positive integers is never an integer,
and a generalization thereof by Trygve Nagell, are shown to be provable inside
a very weak arithmetic, Richard Kaye's $PA^-$, in which there is no induction
axiom whatsoever.


title:
Energy Efficiency in Multi-Hop CDMA Networks: a Game Theoretic Analysis
  Considering Operating Costs

abstract:
  A game-theoretic analysis is used to study the effects of receiver choice and
transmit power on the energy efficiency of multi-hop networks in which the
nodes communicate using Direct-Sequence Code Division Multiple Access
(DS-CDMA). A Nash equilibrium of the game in which the network nodes can choose
their receivers as well as their transmit powers to maximize the total number
of bits they transmit per unit of energy spent (including both transmit and
operating energy) is derived. The energy efficiencies resulting from the use of
different linear multiuser receivers in this context are compared for the
non-cooperative game. Significant gains in energy efficiency are observed when
multiuser receivers, particularly the linear minimum mean-square error (MMSE)
receiver, are used instead of conventional matched filter receivers.


title:
Fractional Aharonov-Bohm oscillation of a two-layer ring with two
  electrons

abstract:
  When a circular ring suffers a special topological transformation, it becomes
a two-layer ring. Due to the special topology of the two-layer ring, orbital
angular momenta are allowed to be a half-integer, this would affect the
traditional Aharonov-Bohm oscillation (ABO). In this paper the fractional ABO
of the ground state energy, persistent current, and dipole transition of a
two-layer ring with two electrons has been studied. Collective and internal
coordinates $\theta_{C}$ and $\phi $ have been introduced. Based on them a very
simple formula for the current has been obtained, the symmetry constraint
imposed on the dipole transition has been clarified, a strict relation between
the photon energies of the dipole radiation and the persistent current of the
ground state has been found. Comparing with the one-layer rings, the period of
the fractional ABO of the two-layer rings becomes much shorter.


title: Information Rates of Minimal Non-Matroid-Related Access Structures

abstract:
  In a secret sharing scheme, shares of a secret are distributed to
participants in such a way that only certain predetermined sets of participants
are qualified to reconstruct the secret. An access structure on a set of
participants specifies which sets are to be qualified. The information rate of
an access structure is a bound on how efficient a secret sharing scheme for
that access structure can be. Marti-Farre and Padro showed that all access
structures with information rate greater than two-thirds are matroid-related,
and Stinson showed that four of the minor-minimal, non-matroid-related access
structures have information rate exactly two-thirds. By a result of Seymour,
there are infinitely many remaining minor-minimal, non-matroid-related access
structures. In this paper we find the exact information rates for all such
structures.


title: Dynatomic cycles for morphisms of projective varieties

abstract:
  We prove the effectivity of the dynatomic cycles for morphisms of projective
varieties. We then analyze the degrees of the dynatomic cycles and
multiplicities of formal periodic points and apply these results to the
existence of periodic points with arbitrarily large primitive periods.


title: Dynamics of k-core percolation

abstract:
  In many network applications nodes are stable provided they have at least k
neighbors, and a network of k-stable nodes is called a k-core. The
vulnerability to random attack is characterized by the size of culling
avalanches which occur after a randomly chosen k-core node is removed.
Simulations of lattices in two, three and four dimensions, as well as small
world networks, indicate that power-law avalanches occur in first order k-core
systems, while truncated avalanches are characteristic of second order cases.


title: Good Reduction of Periodic Points

abstract:
  We consider the dynamical system created by iterating a morphism of a
projective variety defined over the field of fractions of a discrete valuation
ring. We study the primitive period of a periodic point in this field in
relation to the primitive period of the reduced point in the residue field, the
order of the action on the cotangent space, and the characteristic of the
residue field.


title: Kinematics of solid particles in a turbulent protoplanetary disc

abstract:
  We perform numerical simulations of solid particle motion in a shearing box
model of a protoplanetary disc. The accretion flow is turbulent due to the
action of the magnetorotational instability. Aerodynamic drag on the particles
is modelled using the Epstein law with the gas velocity interpolated to the
particle position. The effect of the magnetohydrodynamic turbulence on particle
velocity dispersions is quantified for solids of different stopping times t_s,
or equivalently, different sizes. The anisotropy of the turbulence is reflected
upon the dispersions of the particle velocity components, with the radial
component larger than both the azimuthal and vertical components for particles
larger than ~ 10 cm (assuming minimum-mass solar nebula conditions at 5 AU).
The dispersion of the particle velocity magnitude, as well as that of the
radial and azimuthal components, as functions of stopping time, agree with
previous analytical results for isotropic turbulence. The relative speed
between pairs of particles with the same value of t_s decays faster with
decreasing separation than in the case of solids with different stopping time.
Correlations in the particle number density introduce a non-uniform spatial
distribution of solids in the 10 to 100 cm size range. Any clump of particles
is disrupted by the turbulence in less than one tenth on an orbital period, and
the maximally concentrated clumps are stable against self-gravitational
collapse.


title:
All 2-dimensional links in 4-space live inside a universal 3-dimensional
  polyhedron

abstract:
  The hexabasic book is the cone of the 1-dimensional skeleton of the union of
two tetrahedra glued along a common face. The universal 3-dimensional
polyhedron UP is the product of a segment and the hexabasic book. We show that
any 2-dimensional link in 4-space is isotopic to a surface in UP. The proof is
based on a representation of surfaces in 4-space by marked graphs, links with
double intersections in 3-space. We construct a finitely presented semigroup
whose central elements uniquely encode all isotopy classes of 2-dimensional
links.


title: Finding Rational Periodic Points on Wehler K3 Surfaces

abstract:
  This article examines dynamical systems on a class of K3 surfaces in
$\mathbb{P}^{2} \times \mathbb{P}^{2}$ with an infinite automorphism group. In
particular, this article develops an algorithm to find $\mathbb{Q}$-rational
periodic points using information modulo $p$ for various primes $p$. The
algorithm is applied to exhibit K3 surfaces with $\mathbb{Q}$-rational periodic
points of primitive period $1,...,16$. A portion of the algorithm is then used
to determine the Riemann zeta function modulo 3 of a particular K3 surface and
find a family of K3 surfaces with Picard number two.


title:
1RXSJ173021.5-055933: a cataclysmic variable with a fast-spinning
  magnetic white dwarf

abstract:
  We present the first X-ray observations with the XMM-Newton and INTEGRAL
satellites of the recently discovered cataclysmic variable
1RXSJ173021.5-055933, together with simultaneous UV and coordinated optical
photometry aiming at characterising its broad-band temporal and spectral
properties and classifying this system as a magnetic one. We find that the
X-ray light curve is dominated by the 128s spin period of the accreting white
dwarf in contrast to the far-UV range, which turns out to be unmodulated at a
3sigma level. Near-UV and optical pulses are instead detected at twice the spin
frequency. We identify the contributions from two accreting poles that imply a
moderately inclined dipole field allowing, one pole to dominate at energies at
least up to 10keV, and a secondary that instead is negligible above 5keV. X-ray
spectral analysis reveals the presence of multiple emission components
consisting of optically thin plasma with temperatures ranging from 0.17keV to
60keV and a hot blackbody at ~90eV. The spectrum is also strongly affected by
peculiar absorption components consisting of two high-density
(~3x10^(21)cm^(-2) and ~2x10^(23)cm^(-2)) intervening columns, plus a warm
absorber. The last is detected from an OVII absorption edge at 0.74keV, which
suggests that photoionization of pre-shock material is also occurring in this
system. The observed properties indicate that the accretor in
1RXSJ173021.5-055933 is a white dwarf with a likely weak magnetic field, thus
confirming this cataclysmic variable as an intermediate polar (IP) with one of
the most extreme spin-to-orbit period ratios. This system also joins the small
group of IPs showing a soft X-ray reprocessed component, suggesting that this
characteristics is not uncommon in these systems.


title:
Submillimeter Galaxies at z~2: Evidence for Major Mergers & Constraints
  on Lifetimes, IMF and CO-H2 Conversion Factor

abstract:
  We report sub-arcsecond resolution IRAM PdBI millimeter CO interferometry of
four z~2 submillimeter galaxies (SMGs), and sensitive CO (3-2) flux limits
toward three z~2 UV-/optically selected star forming galaxies. The new data
reveal for the first time spatially resolved CO gas kinematics in the observed
SMGs. Two of the SMGs show double or multiple morphologies, with complex,
disturbed gas motions. The other two SMGs exhibit CO velocity gradients of ~500
km/s across 0.2 arcsec (1.6 kpc) diameter regions, suggesting that the star
forming gas is in compact, rotating disks. Our data provide compelling evidence
that these SMGs represent extreme, short-lived 'maximum' star forming events in
highly dissipative mergers of gas rich galaxies. The resulting high mass
surface and volume densities of SMGs are similar to those of compact quiescent
galaxies in the same redshift range, and much higher than those in local
spheroids. From the ratio of the comoving volume densities of SMGs and
quiescent galaxies in the same mass and redshift ranges, and from the
comparison of gas exhaustion time scales and stellar ages, we estimate that the
SMG phase duration is about 100 Myrs. Our analysis of SMGs and optically/UV
selected high redshift star forming galaxies supports a 'universal' Chabrier
IMF as being valid over the star forming history of these galaxies. We find
that the 12CO luminosity to total gas mass conversion factors at z~2-3 are
probably similar to those assumed at z~0. The implied gas fractions in our
sample galaxies range from 20 to 50%.


title:
Self-organization and the selection of pinwheel density in visual
  cortical development

abstract:
  Self-organization of neural circuitry is an appealing framework for
understanding cortical development, yet its applicability remains unconfirmed.
Models for the self-organization of neural circuits have been proposed, but
experimentally testable predictions of these models have been less clear. The
visual cortex contains a large number of topological point defects, called
pinwheels, which are detectable in experiments and therefore in principle well
suited for testing predictions of self-organization empirically. Here, we
analytically calculate the density of pinwheels predicted by a pattern
formation model of visual cortical development. An important factor controlling
the density of pinwheels in this model appears to be the presence of non-local
long-range interactions, a property which distinguishes cortical circuits from
many nonliving systems in which self-organization has been studied. We show
that in the limit where the range of these interactions is infinite, the
average pinwheel density converges to $\pi$. Moreover, an average pinwheel
density close to this value is robustly selected even for intermediate
interaction ranges, a regime arguably covering interaction-ranges in a wide
range of different species. In conclusion, our paper provides the first direct
theoretical demonstration and analysis of pinwheel density selection in models
of cortical self-organization and suggests to quantitatively probe this type of
prediction in future high-precision experiments.


title:
The nonlinear-by-switching systems (a heuristic discussion of some basic
  singular systems)

abstract:
  Electronics has changed greatly during recent decades, and some its basic
concepts should be revisited. Starting from the sampling procedure, we consider
some mathematical, physical and engineering aspects related to singular, mainly
switching, systems. Since the field of such systems is very rich in content, a
certain line of treatment had to be chosen, making the work a theoretical
introduction to the field of the systems. The focus is on the conditions for a
singular system to be linear or nonlinear, and one studies more deeply what
"nonlinearity" is (can be). In order to uniformly present mathematical,
physical and circuit arguments, the work is given the frame of a discussion in
which the relevant specialists participate.


title: Helical Magnetic Fields from Sphaleron Decay and Baryogenesis

abstract:
  Many models of baryogenesis rely on anomalous particle physics processes to
give baryon number violation. By numerically evolving the electroweak equations
on a lattice, we show that baryogenesis in these models creates helical cosmic
magnetic fields. After a transitory period, electroweak dynamics is found to
conserve the Chern-Simons number and the total electromagnetic helicity. We
argue that baryogenesis could lead to magnetic fields of nano-Gauss strength
today on astrophysical length scales. In addition to being astrophysically
relevant, such helical magnetic fields can provide an independent probe of
baryogenesis and CP violation in particle physics.


title: A path following algorithm for the graph matching problem

abstract:
  We propose a convex-concave programming approach for the labeled weighted
graph matching problem. The convex-concave programming formulation is obtained
by rewriting the weighted graph matching problem as a least-square problem on
the set of permutation matrices and relaxing it to two different optimization
problems: a quadratic convex and a quadratic concave optimization problem on
the set of doubly stochastic matrices. The concave relaxation has the same
global minimum as the initial graph matching problem, but the search for its
global minimum is also a hard combinatorial problem. We therefore construct an
approximation of the concave problem solution by following a solution path of a
convex-concave problem obtained by linear interpolation of the convex and
concave formulations, starting from the convex relaxation. This method allows
to easily integrate the information on graph label similarities into the
optimization problem, and therefore to perform labeled weighted graph matching.
The algorithm is compared with some of the best performing graph matching
methods on four datasets: simulated graphs, QAPLib, retina vessel images and
handwritten chinese characters. In all cases, the results are competitive with
the state-of-the-art.


title:
Effects of Intrinsic Spin-Relaxation in Molecular Magnets on
  Current-Induced Magnetic Switching

abstract:
  Current-induced magnetic switching of a single magnetic molecule attached to
two ferromagnetic contacts is considered theoretically, with the main emphasis
put on the role of intrinsic spin relaxation processes. It is shown that
spin-polarized current can switch magnetic moment of the molecule, despite of
the intrinsic spin relaxation in the molecule. The latter processes increase
the threshold voltage (current) above which the switching takes place.


title:
Hadronic Uncertainties in the Elastic Scattering of Supersymmetric Dark
  Matter

abstract:
  We review the uncertainties in the spin-independent and -dependent elastic
scattering cross sections of supersymmetric dark matter particles on protons
and neutrons. We propagate the uncertainties in quark masses and hadronic
matrix elements that are related to the $\pi$-nucleon $\sigma$ term and the
spin content of the nucleon. By far the largest single uncertainty is that in
spin-independent scattering induced by our ignorance of the $<N | {\bar q} q |
N>$ matrix elements linked to the $\pi$-nucleon $\sigma$ term, which affects
the ratio of cross sections on proton and neutron targets as well as their
absolute values. This uncertainty is already impacting the interpretations of
experimental searches for cold dark matter. {\it We plead for an experimental
campaign to determine better the $\pi$-nucleon $\sigma$ term.} Uncertainties in
the spin content of the proton affect significantly, but less strongly, the
calculation of rates used in indirect searches.


title: A Matrix Model for Black Hole Thermalization

abstract:
  We present a matrix model which is intended as a toy model of the gauge dual
of an AdS black hole. In particular, it captures the key property that at
infinite $N$ correlators decay to zero on long time scales, while at finite $N$
this cannot happen. The model consists of a harmonic oscillator in the adjoint
which acts as a heat bath for a particle in the fundamental representation. The
Schwinger-Dyson equation reduces to a closed recursion relation, which we study
by various analytical and numerical methods. We discuss some implications for
the information problem.


title: Difficulties with the QPOs Resonance Model

abstract:
  High frequency quasi-periodic oscillations (HFQPOs) have been detected in
microquasars and neutron star systems. The resonance model suggested by
Kluzniak & Abramowicz (2000) explains twin QPOs as two weakly coupled nonlinear
resonant epicyclic modes in the accretion disk. Although this model
successfully explains many features of the observed QPOs, it still faces
difficulties and shortcomings. Here we summarize the aspects of the theory that
remain a puzzle and we briefly discuss likely developments.


title: Measuring Baryon Acoustic Oscillations with Millions of Supernovae

abstract:
  Since type Ia Supernovae (SNe) explode in galaxies, they can, in principle,
be used as the same tracer of the large-scale structure as their hosts to
measure baryon acoustic oscillations (BAOs). To realize this, one must obtain a
dense integrated sampling of SNe over a large fraction of the sky, which may
only be achievable photometrically with future projects such as the Large
Synoptic Survey Telescope. The advantage of SN BAOs is that SNe have more
uniform luminosities and more accurate photometric redshifts than galaxies, but
the disadvantage is that they are transitory and hard to obtain in large number
at high redshift. We find that a half-sky photometric SN survey to redshift z =
0.8 is able to measure the baryon signature in the SN spatial power spectrum.
Although dark energy constraints from SN BAOs are weak, they can significantly
improve the results from SN luminosity distances of the same data, and the
combination of the two is no longer sensitive to cosmic microwave background
priors.


title:
Theory of Thermal Motion in Electromagnetically Induced Transparency:
  Diffusion, Doppler, Dicke and Ramsey

abstract:
  We present a theoretical model for electromagnetically induced transparency
(EIT) in vapor, that incorporates atomic motion and velocity-changing
collisions into the dynamics of the density-matrix distribution. Within a
unified formalism we demonstrate various motional effects, known for EIT in
vapor: Doppler-broadening of the absorption spectrum; Dicke-narrowing and
time-of-flight broadening of the transmission window for a finite-sized probe;
Diffusion of atomic coherence during storage of light and diffusion of the
light-matter excitation during slow-light propagation; and Ramsey-narrowing of
the spectrum for a probe and pump beams of finite-size.


title: Isotropic-Cholesteric Transition of a Weakly Chiral Elastomer Cylinder

abstract:
  When a chiral isotropic elastomer is brought to low temperature cholesteric
phase, the nematic degree of freedom tends to order and form a helix. Due to
the nemato-elastic coupling, this also leads to elastic deformation of the
polymer network that is locally coaxial with the nematic order. However, the
helical structure of nematic order is incompatible with the energetically
preferred elastic deformation. The system is therefore frustrated and
appropriate compromise has to be achieved between the nematic ordering and the
elastic deformation. For a strongly chiral elastomer whose pitch is much
smaller than the system size, this problem has been studied by Pelcotivs and
Meyer, as well as by Warner. In this work, we study the isotropic-cholesteric
transition in the weak chirality limit, where the pitch is comparable or much
larger than system size. We compare two possible solutions: a helical state as
well as a double twist state. We find that the double twist state very
efficiently minimizes both the elastic free energy and the chiral nematic free
energy. On the other hand, the pitch of the helical state is strongly affected
by the nemato-elastic coupling. As a result this state is not efficient in
minimizing the chiral nematic free energy.


title: Classical thermodynamics of gravitational collapse

abstract:
  We study numerically gravitational collapse of a spherically symmetric
instanton particle in five dimensions. We show that the late stages of the
process are characterized by a nearly constant ``free energy'', the value of
which matches (within numerical uncertainties) the value obtained from standard
black-hole thermodynamics. This suggests a purely classical interpretation of
the free energy of a black hole.


title:
X-ray emission from active galactic nuclei with intermediate mass black
  holes

abstract:
  We present a systematic X-ray study of eight AGNs with intermediate mass
black holes (M_BH 8-95x10^4 Msun) based on 12 XMM-Newton observations. The
sample includes the two prototype AGNs in this class - NGC4395 and POX52 and
six other AGNs discovered with the SDSS. These AGNs show some of the strongest
X-ray variability with the normalized excess variances being the largest and
the power density break time scales being the shortest observed among
radio-quiet AGNs. The excess variance -- luminosity correlation appears to
depend on both the BH mass and the Eddington luminosity ratio. The break time
scale -- black hole mass relations for AGN with IMBHs are consistent with that
observed for massive AGNs. We find that the FWHM of the Hbeta or Halpha line is
uncorrelated with the BH mass, but shows strong anticorrelation with the
Eddington luminosity ratio. Four AGNs show clear evidence for soft X-ray excess
emission (kT_in~150-200eV). X-ray spectra of three other AGNs are consistent
with the presence of the soft excess emission. NGC4395 with lowest L/L_Edd
lacks the soft excess emission. Evidently small black mass is not the primary
driver of strong soft X-ray excess emission from AGNs. The X-ray spectral
properties and optical-to-X-ray spectral energy distributions of these AGNs are
similar to those of Seyfert 1 galaxies. The observed X-ray/UV properties of
AGNs with IMBHs are consistent with these AGNs being low mass extension of more
massive AGNs; those with high Eddington luminosity ratio looking more like
narrow-line Seyfert 1s while those with low $L/L_{Edd}$ looking more like
broad-line Seyfert 1s.