title: ATCA observations of the very young Planetary Nebula SAO 244567

abstract:
  The radio emission from the youngest known Planetary nebula, SAO244567, has
been mapped at 1384, 2368, 4800, 8640, 16832 and 18752 MHz by using the
Australian Telescope Compact Array (ATCA). These observations constitute the
first detailed radio study of this very interesting object, as they allow us to
obtain the overall radio morphology of the source and to compute, for the first
time, the radio spectrum up to millimetre range. Radio emission is consistent
with free-free from a wind-like shell, which is also the region where most of
the [OIII] comes from as revealed by HST images. Physical parameters of the
radio nebula and of the central star were derived, all consistent with SAO
244567 being a very young Planetary Nebula still embedded in the dusty remnant
of the AGB phase. The optically thin radio flux density appear to decrease when
compared to data from the literature. Even very appealing, the variability of
the radio emission, probably related to the evolution of the central object,
needs further investigations.


title: Generalized Swanson models and their solutions

abstract:
  We analyze a class of non-Hermitian quadratic Hamiltonians, which are of the
form $ H = {\cal{A}}^{\dagger} {\cal{A}} + \alpha {\cal{A}} ^2 + \beta
{\cal{A}}^{\dagger 2} $, where $ \alpha, \beta $ are real constants, with $
\alpha \neq \beta $, and ${\cal{A}}^{\dagger}$ and ${\cal{A}}$ are generalized
creation and annihilation operators. Thus these Hamiltonians may be classified
as generalized Swanson models. It is shown that the eigenenergies are real for
a certain range of values of the parameters. A similarity transformation
$\rho$, mapping the non-Hermitian Hamiltonian $H$ to a Hermitian one $h$, is
also obtained. It is shown that $H$ and $h$ share identical energies. As
explicit examples, the solutions of a couple of models based on the
trigonometric Rosen-Morse I and the hyperbolic Rosen-Morse II type potentials
are obtained. We also study the case when the non-Hermitian Hamiltonian is
${\cal{PT}}$ symmetric.


title: Newton's method and Baker domains

abstract:
  We show that there exists an entire function f without zeros for which the
associated Newton function N(z)=z-f(z)/f'(z) is a transcendental meromorphic
functions without Baker domains. We also show that there exists an entire
function f with exactly one zero for which the complement of the immediate
attracting basin has at least two components and contains no invariant Baker
domains of N. The second result answers a question of J. Rueckert and D.
Schleicher while the first one gives a partial answer to a question of X. Buff.


title: A Micro Molecular Bipolar Outflow From HL Tau

abstract:
  We present detailed geometry and kinematics of the inner outflow toward HL
Tau observed using Near Infrared Integral Field Spectograph (NIFS) at the
Gemini-North 8-m Observatory. We analyzed H2 2.122 um emission and [Fe II]
1.644 um line emission as well as the adjacent continuum observed at a <0".2
resolution. The H2 emission shows (1) a bubble-like geometry to the northeast
of the star, as briefly reported in the previous paper, and (2) faint emission
in the southwest counterflow, which has been revealed through careful analysis.
The emission on both sides of the star show an arc 1".0 away from the star,
exhibiting a bipolar symmetry. Different brightness and morphologies in the
northeast and southwest flows are attributed to absorption and obscuration of
the latter by a flattened envelope and a circumstellar disk. The H2 emission
shows a remarkably different morphology from the collimated jet seen in [Fe II]
emission. The positions of some features coincide with scattering continuum,
indicating that these are associated with cavities in the dusty envelope. Such
properties are similar to millimeter CO outflows, although the spatial scale of
the H2 outflow in our image (~150 AU) is strikingly smaller than the mm
outflows, which often extend over 1000-10000 AU scales. The position-velocity
diagram of the H2 and [Fe II] emission do not show any evidence for kinematic
interaction between these flows. All results described above support the
scenario that the jet is surrounded by an unseen wide-angled wind, which
interacts with the ambient gas and produce the bipolar cavity and shocked H2
emission.


title: Z2Z4-linear codes: generator matrices and duality

abstract:
  A code ${\cal C}$ is $\Z_2\Z_4$-additive if the set of coordinates can be
partitioned into two subsets $X$ and $Y$ such that the punctured code of ${\cal
C}$ by deleting the coordinates outside $X$ (respectively, $Y$) is a binary
linear code (respectively, a quaternary linear code). In this paper
$\Z_2\Z_4$-additive codes are studied. Their corresponding binary images, via
the Gray map, are $\Z_2\Z_4$-linear codes, which seem to be a very
distinguished class of binary group codes.
  As for binary and quaternary linear codes, for these codes the fundamental
parameters are found and standard forms for generator and parity check matrices
are given. For this, the appropriate inner product is deduced and the concept
of duality for $\Z_2\Z_4$-additive codes is defined. Moreover, the parameters
of the dual codes are computed. Finally, some conditions for self-duality of
$\Z_2\Z_4$-additive codes are given.


title:
The pion-pion scattering amplitude. III: Improving the analysis with
  forward dispersion relations and Roy equations

abstract:
  We complete and improve the fits to experimental $\pi\pi$ scattering
amplitudes, both at low and high energies, that we performed in the previous
papers of this series. We then verify that the corresponding amplitudes satisfy
analyticity requirements, in the form of partial wave analyticity at low
energies, forward dispersion relations (FDR) at all energies, and Roy equations
below$\bar{K}K$ threshold; the first by construction, the last two, inside
experimental errors. Then we repeat the fits including as constraints FDR and
Roy equations. The ensuing central values of the various scattering amplitudes
verify very accurately FDR and, especially, Roy equations, and change very
little from what we found by just fitting data, with the exception of the D2
wave phase shift, for which one parameter moves by $1.5 \sigma$. These improved
parametrizations therefore provide a reliable representation of pion-pion
amplitudes with which one can test various physical relations. We also present
a list of low energy parameters and other observables. In particular, we find
$a_0^{(0)}=0.223\pm0.009 M^{-1}_\pi$, $a_0^{(2)}=-0.0444\pm0.0045 M^{-1}_\pi$
and $\delta_0^{(0)}(m^2_K)-\delta_0^{(2)}(m^2_K)=50.9\pm1.2^{\rm o}$.


title: Optimal properties of some Bayesian inferences

abstract:
  Relative surprise regions are shown to minimize, among Bayesian credible
regions, the prior probability of covering a false value from the prior. Such
regions are also shown to be unbiased in the sense that the prior probability
of covering a false value is bounded above by the prior probability of covering
the true value. Relative surprise regions are shown to maximize both the Bayes
factor in favor of the region containing the true value and the relative belief
ratio, among all credible regions with the same posterior content. Relative
surprise regions emerge naturally when we consider equivalence classes of
credible regions generated via reparameterizations.


title: Convexity properties of gradient maps

abstract:
  We consider the action of a real reductive group G on a Kaehler manifold Z
which is the restriction of a holomorphic action of the complexified group G^C.
We assume that the induced action of a compatible maximal compact subgroup U of
G^C on Z is Hamiltonian. We have an associated gradient map obtained from a
Cartan decomposition of G. For a G-stable subset Y of Z we consider convexity
properties of the intersection of the image of Y under the gradient map with a
closed Weyl chamber. Our main result is a Convexity Theorem for real
semi-algebraic subsets Y of the projective space corresponding to a unitary
representation of U.


title:
Verification of Ptime Reducibility for system F Terms: Type Inference
  in<br> Dual Light Affine Logic

abstract:
  In a previous work Baillot and Terui introduced Dual light affine logic
(DLAL) as a variant of Light linear logic suitable for guaranteeing complexity
properties on lambda calculus terms: all typable terms can be evaluated in
polynomial time by beta reduction and all Ptime functions can be represented.
In the present work we address the problem of typing lambda-terms in
second-order DLAL. For that we give a procedure which, starting with a term
typed in system F, determines whether it is typable in DLAL and outputs a
concrete typing if there exists any. We show that our procedure can be run in
time polynomial in the size of the original Church typed system F term.


title:
Dynamically induced scalar quark confinement: A link between chiral
  symmetry breaking and confinement

abstract:
  Employing functional approaches the infrared behaviour of Landau gauge QCD
vertex functions is investigated. Results for the ghost-gluon, three-gluon and
quark-gluon vertex functions are presented. As can be analytically shown a
linear rising potential between heavy quarks is generated by infrared
singularities in the dressed quark-gluon vertex. The selfconsistent mechanism
that generates these singularities implies the existence of scalar Dirac
amplitudes of the full vertex and the quark propagator. These amplitudes can
only be present when chiral symmetry is broken, either explicitly or
dynamically. The corresponding relations thus constitute a novel mechanism that
directly links chiral symmetry breaking with confinement.


title: A note on local trigonal fibrations

abstract:
  We show that some of centeral fibers of degenerations of hyperelliptic curves
are realized as those trigonal curves. In particular, any hyperelliptic curve
can be the central fiber of a degeneration of trigonal curves.


title: Eigenmode of Decision-By-Majority Process on Complex Networks

abstract:
  The nature of dynamics of opinion formation modeled as a decision-by-majority
process in complex networks is investigated using eigenmode analysis.
Hamiltonian of the system is defined, and estimated by eigenvectors of the
adjacency matrix constructed from several network models. The eigenmodes of
initial and final state of the dynamics are analyzed by numerical studies. We
show that the magnitude of the largest eigenvector at the initial states are
key determinant for the resulting dynamics.


title: Multipartite circulant states with positive partial transposes

abstract:
  We construct a large class of multipartite qudit states which are positive
under the family of partial transpositions. The construction is based on
certain direct sum decomposition of the total Hilbert space displaying
characteristic circular structure and hence generalizes a class of bipartite
circulant states proposed recently by the authors. This class contains many
well known examples of multipartite quantum states from the literature and
gives rise to a huge family of completely new states.


title:
Why the $a_1$ meson might be a difficult messenger for the restoration
  of chiral symmetry

abstract:
  We perform a theoretical analysis of the $a_1$ resonance mass spectrum in
ultra-relativistic heavy ion collisions within a hadron/string transport
approach. Predictions for the $a_1$ yield and its mass distribution are given
for the GSI-FAIR and the critRHIC energy regime. The potential of the $a_1$
meson as a signal for chiral symmetry restoration is explored. In view of the
latest discussion, we investigate the decay channel $a_1 \to \gamma\pi$ in
detail and find a strong bias towards low $a_1$ masses. This apparent mass
shift of the $a_1$ if observed in the $\gamma\pi$ channel might render a
possible mass shift due to chiral symmetry restoration very difficult to
disentangle from the decay kinematics.


title:
SmB$_6$: Topological insulator or semiconductor with valence-fluctuation
  induced hopping transport?

abstract:
  We advert to the fact that presence of valence fluctuations (VFs) in
semiconductors with in-gap impurity bands unconditionally leads to dynamical
changes (fluctuations) of energies of localized impurity states. We provide
arguments that in the impurity subnetwork consisting of centers having energy
levels fluctuating around the Fermi energy there exist favorable conditions for
hops from occupied states to empty states of less energy. Consequently, we
propose original valence-fluctuation induced hopping mechanism as a new
possibility to explain unusual metallic-like conduction of SmB$_6$ and other
Kondo insulators experimentally observed at lowest temperatures. Interestingly,
the proposed mechanism infers enhanced metallic-like surface conductivity of
SmB$_6$, what resembles a characteristic property of topological insulator, and
is in agreement with experimental observations attempting to prove the
existence of topologically protected surface state in SmB$_6$.


title:
Self-consistent simulation of quantum wires defined by local oxidation
  of Ga[Al]As heterostructures

abstract:
  We calculate the electronic width of quantum wires as a function of their
lithographic width in analogy to experiments performed on nanostructures
defined by local oxidation of Ga[Al]As heterostructures. Two--dimensional
simulations of two parallel oxide lines on top of a Ga[Al]As heterostructure
defining a quantum wire are carried out in the framework of Density Functional
Theory in the Local Density Approximation and are found to be in agreement with
measurements. Quantitative assessment of the influence of various experimental
uncertainties is given. The most influential parameter turns out to be the
oxide line depth, followed by its exact shape and the effect of background
doping (in decreasing order).


title:
Finite Size Scaling for the O(N) universality class from Renormalization
  Group Methods

abstract:
  The QCD phase diagram at finite temperature and density is a topic of
considerable interest. Although much progress has been made in recent years,
some open questions remain. Even at zero density, the order of the transition
for two light flavors of fermions has not yet been conclusively established.
While considerable evidence exists in favor of a second-order transition for
massless quarks and a crossover for massive quarks, some recent results with
two flavors of staggered fermions suggest a transition of first order.
  Since lattice simulations are performed in finite simulation volumes, actual
phase transitions cannot be observed directly. Thus, finite-size scaling is a
very useful tool in the analysis of lattice data. By comparing the scaling
behavior of observables to the expected scaling properties, values of critical
exponents can be confirmed and the order as well as the universality class of a
transition can be established. In the comparison to lattice QCD results, the
critical exponents and the universal scaling functions have been obtained
mainly by means of lattice simulations of O(N) spin models, and results are
usually restricted to the critical temperature or the point at which the
susceptibilities peak.
  We propose to use a non-perturbative Renormalization Group method for this
purpose. We have calculated the critical finite-size scaling behavior and the
universal scaling functions for the three-dimensional O(4)-model for a wide
range of temperatures and values of the symmetry breaking parameter. Our
results are suitable for a comparison to lattice QCD results for the chiral
susceptibility and the order parameter and can be used to check the consistency
of the finite-size scaling behavior with that of the O(N) universality class.


title: On the Effective Action of Noncommutative Yang-Mills Theory

abstract:
  We compute here the Yang-Mills effective action on Moyal space by integrating
over the scalar fields in a noncommutative scalar field theory with harmonic
term, minimally coupled to an external gauge potential. We also explain the
special regularisation scheme chosen here and give some links to the Schwinger
parametric representation. Finally, we discuss the results obtained: a
noncommutative possibly renormalisable Yang-Mills theory.


title: Bimonads and Hopf monads on categories

abstract:
  The purpose of this paper is to develop a theory of bimonads and Hopf monads
on arbitrary categories thus providing the possibility to transfer the
essentials of the theory of Hopf algebras in vector spaces to more general
settings. There are several extensions of this theory to {\em monoidal}
categories which in a certain sense follow the classical trace. Here we do not
pose any conditions on our base category but we do refer to the monoidal
structure of the category of endofunctors on any category $\A$ and by this we
retain some of the combinatorial complexity which makes the theory so
interesting. As a basic tool we use distributive laws between monads and
comonads (entwinings) on $\A$: we define a {\em bimonad} on $\A$ as an
endofunctor $B$ which is a monad and a comonad with an entwining $\lambda:BB\to
BB$ satisfying certain conditions. This $\lambda$ is also employed to define
the category $\A^B_B$ of (mixed) $B$-bimodules. In the classical situation, an
entwining $\lambda$ is derived from the twist map for vector spaces. Here this
need not be the case but there may exist special distributive laws $\tau:BB\to
BB$ satisfying the Yang-Baxter equation ({\em local prebraidings}) which induce
an entwining $\lambda$ and lead to an extension of the theory of {\em braided
Hopf algebras}. An antipode is defined as a natural transformation $S:B\to B$
with special properties and for categories $\A$ with limits or colimits and
bimonads $B$ preserving them, the existence of an antipode is equivalent to $B$
inducing an equivalence between $\A$ and the category $\A^B_B$ of
$B$-bimodules. This is a general form of the {\em Fundamental Theorem} of Hopf
algebras.


title: Recent progress on color confinement

abstract:
  The status is reviewed of the dual superconductivity of QCD vacuum as a
mechanism of color confinement.


title:
Unbiased estimates of galaxy scaling relations from photometric redshift
  surveys

abstract:
  Many physical properties of galaxies correlate with one another, and these
correlations are often used to constrain galaxy formation models. Such
correlations include the color-magnitude relation, the luminosity-size
relation, the Fundamental Plane, etc. However, the transformation from
observable (e.g. angular size, apparent brightness) to physical quantity
(physical size, luminosity), is often distance-dependent. Noise in the distance
estimate will lead to biased estimates of these correlations, thus compromising
the ability of photometric redshift surveys to constrain galaxy formation
models. We describe two methods which can remove this bias. One is a
generalization of the V_max method, and the other is a maximum likelihood
approach. We illustrate their effectiveness by studying the size-luminosity
relation in a mock catalog, although both methods can be applied to other
scaling relations as well. We show that if one simply uses photometric
redshifts one obtains a biased relation; our methods correct for this bias and
recover the true relation.


title:
Track Based Alignment of the ATLAS Silicon Detectors with the Robust
  Alignment Algorithm

abstract:
  The Robust Alignment algorithm for the ATLAS silicon detectors is presented.
It is an iterative method based on centering residual and overlap residual
distributions. Tests on simulated and real data are discussed.


title: Planetary Stability Zones in Hierarchical Triple Star Systems

abstract:
  A symplectic integrator algorithm suitable for hierarchical triple systems is
formulated and tested. The positions of the stars are followed in hierarchical
Jacobi coordinates, whilst the planets are referenced purely to their primary.
The algorithm is fast, accurate and easily generalised to incorporate
collisions. There are five distinct cases -- circumtriple orbits, circumbinary
orbits and circumstellar orbits around each of the stars in the hierarchical
triple -- which require a different formulation of the symplectic integration
algorithm. As an application, a survey of the stability zones for planets in
hierarchical triples is presented, with the case of a single planet orbiting
the inner binary considered in detail. Fits to the inner and outer edges of the
stability zone are computed. Considering the hierarchical triple as two
decoupled binary systems, the earlier work of Holman & Wiegert on binaries is
shown to be applicable to triples, except in the cases of high eccentricities
and close or massive stars. Application to triple stars with good data in the
multiple star catalogue suggests that more than 50 per cent are unable to
support circumbinary planets, as the stable zone is almost non-existent.


title:
Density functional theory of inhomogeneous liquids. I. The liquid-vapor
  interface in Lennard-Jones fluids

abstract:
  A simple model is proposed for the direct correlation function (DCF) for
simple fluids consisting of a hard-core contribution, a simple parametrized
core correction, and a mean-field tail. The model requires as input only the
free energy of the homogeneous fluid, obtained, e.g., from thermodynamic
perturbation theory. Comparison to the DCF obtained from simulation of a
Lennard-Jones fluid shows this to be a surprisingly good approximation for a
wide range of densities. The model is used to construct a density functional
theory for inhomogeneous fluids which is applied to the problem of calculating
the surface tension of the liquid-vapor interface. The numerical values found
are in good agreement with simulation.


title: SU(2) Yang-Mills thermodynamics and photon physics

abstract:
  Based on quantitative predictions enabled by a nonperturbative approach to
Yang-Mills thermodynamics it is explained why the physics of photon {\sl
propagation} is not unlikely rooted in pure SU(2) gauge dynamics.


title: Numerical study of metastable states in the T=0 RFIM

abstract:
  We study numerically the number of single-spin-flip stable states in the T=0
Random Field Ising Model (RFIM) on random regular graphs of connectivity $z=2$
and $z=4$ and on the cubic lattice. The annealed and quenched complexities
(i.e. the entropy densities) of the metastable states with given magnetization
are calculated as a function of the external magnetic field. The results show
that the appearance of a (disorder-induced) out-of-equilibrium phase transition
in the magnetization hysteresis loop at low disorder can be ascribed to a
change in the distribution of the metastable states in the field-magnetization
plane.


title:
Improved estimation of the MSEs and the MSE matrices for shrinkage
  estimators of multivariate normal means and their applications

abstract:
  In this article we provide some nonnegative and positive estimators of the
mean squared errors(MSEs) for shrinkage estimators of multivariate normal
means. Proposed estimators are shown to improve on the uniformly minimum
variance unbiased estimator(UMVUE) under a quadratic loss criterion. A similar
improvement is also obtained for the estimators of the MSE matrices for
shrinkage estimators. We also apply the proposed estimators of the MSE matrix
to form confidence sets centered at shrinkage estimators and show their
usefulness through numerical experiments.


title: Combinatorial Alexander Duality -- a Short and Elementary Proof

abstract:
  Let X be a simplicial complex with the ground set V. Define its Alexander
dual as a simplicial complex X* = {A \subset V: V \setminus A \notin X}. The
combinatorial Alexander duality states that the i-th reduced homology group of
X is isomorphic to the (|V|-i-3)-th reduced cohomology group of X* (over a
given commutative ring R). We give a self-contained proof.


title: Baryon masses with dynamical twisted mass fermions

abstract:
  We present results on the mass of the nucleon and the $\Delta$ using two
dynamical degenerate twisted mass quarks. The evaluation is performed at four
quark masses corresponding to a pion mass in the range of 690-300 MeV on
lattices of size 2.1 fm and 2.7 fm. We check for cutoff effects by evaluating
these baryon masses on lattices of spatial size 2.1 fm with lattice spacings
$a(\beta=3.9)=0.0855(6)$ fm and $a(\beta=4.05)=0.0666(6)$ fm, determined from
the pion sector and find them to be within our statistical errors. Lattice
results are extrapolated to the physical limit using continuum chiral
perturbation theory.
  The nucleon mass at the physical point provides a determination of the
lattice spacing. Using heavy baryon chiral perturbation theory at ${\cal
O}(p^3)$ we find $a(\beta=3.9)=0.0879(12)$ fm, with a systematic error due to
the chiral extrapolation estimated to be about the same as the statistical
error. This value of the lattice spacing is in good agreement with the value
determined from the pion sector. We check for isospin breaking in the
$\Delta$-system. We find that $\Delta^{++,-}$ and $\Delta^{+,0}$ are almost
degenerate pointing to small flavor violating effects.


title: Confinement and dual superconductivity of QCD vacuum

abstract: The mechanism of dual superconductivity for confinement is reviewed.


title:
An alternative hypothesis for the outburst mechanism in Supergiant Fast
  X-ray Transients: the case of IGR J11215-5952

abstract:
  (ABRIDGED)- The physical mechanism responsible for the short outbursts in a
recently recognized class of High Mass X-ray Binaries, the Supergiant Fast
X-ray Transients (SFXTs), is still unknown. Two main hypotheses have been
proposed to date: the sudden accretion by the compact object of small ejections
originating in a clumpy wind from the supergiant donor, or outbursts produced
at (or near) the periastron passage in wide and eccentric orbits, in order to
explain the low (1E32 erg/s) quiescent emission.Neither proposed mechanisms
seem to explain the whole phenomenology of these sources. Here we propose a new
explanation for the outburst mechanism, based on new X-ray observations of the
unique SFXT known to display periodic outbursts, IGRJ11215-5952. We performed
three Target of Opportunity observations with Swift, XMM-Newton and INTEGRAL at
the time of the fifth outburst, expected on 2007 February 9. Swift observations
of the February 2007 outburst have been reported elsewhere. Another ToO with
Swift was performed in July 2007, in order to monitor the supposed ``apastron''
passage. A second unexpected outburst was discovered on 2007 July 24, after
about 165 days from the February 2007 outburst. The new X-ray observations
allow us to propose an alternative hypothesis for the outburst mechanism in
SFXTs, linked to the possible presence of a second wind component,in the form
of an equatorial disk from the supergiant donor. We discuss the applicability
of the model to the short outburst durations of all other SFXTs, where a clear
periodicity in the outbursts has not been found yet. The new outburst from
IGRJ11215-5952 observed in July suggests that the true orbital period is
~165days, instead of 329days, as previously thought.


title:
Autoresonant control of the many-electron dynamics in nonparabolic
  quantum wells

abstract:
  The optical response of nonparabolic quantum wells is dominated by a strong
peak at the plasmon frequency. When the electrons reach the anharmonic regions,
resonant absorption becomes inefficient. This limitation is overcome by using a
chirped laser pulse in the autoresonant regime. By direct simulations using the
Wigner phase-space approach, the authors prove that, with a sequence of just a
few pulses, electrons can be efficiently detrapped from a nonparabolic well.
For an array of multiple quantum wells, they can create and control an
electronic current by suitably applying an autoresonant laser pulse and a
slowly varying dc electric field.


title: Stochastic Cutoff Method for Long-Range Interacting Systems

abstract:
  A new Monte-Carlo method for long-range interacting systems is presented.
This method consists of eliminating interactions stochastically with the
detailed balance condition satisfied. When a pairwise interaction $V_{ij}$ of a
$N$-particle system decreases with the distance as $r_{ij}^{-\alpha}$,
computational time per one Monte Carlo step is ${\cal O}(N)$ for $\alpha \ge d$
and ${\cal O}(N^{2-\alpha/d})$ for $\alpha < d$, where $d$ is the spatial
dimension. We apply the method to a two-dimensional magnetic dipolar system.
The method enables us to treat a huge system of $256^2$ spins with reasonable
computational time, and reproduces a circular order originated from long-range
dipolar interactions.


title: The structure of Sally modules of rank one

abstract:
  A complete structure theorem of Sally modules of $\fkm$-primary ideals $I$ in
a Cohen-Macaulay local ring $(A, \m)$ satisfying the equality
$\e_1(I)=\e_0(I)-\ell_A(A/I)+1$ is given, where $\e_0(I)$ and $\e_1(I)$ denote
the first two Hilbert coefficients of $I$.


title: Dark matter-wave solitons in the dimensionality crossover

abstract:
  We consider the statics and dynamics of dark matter-wave solitons in the
dimensionality crossover regime from 3D to 1D. There, using the nonpolynomial
Schr\"{o}dinger mean-field model, we find that the anomalous mode of the
Bogoliubov spectrum has an eigenfrequency which coincides with the soliton
oscillation frequency obtained by the 3D Gross-Pitaevskii model. We show that
substantial deviations (of order of 10% or more) from the characteristic
frequency $\omega_{z}/\sqrt{2}$ ($\omega_{z}$ being the longitudinal trap
frequency) are possible even in the purely 1D regime.


title:
Comparison of bar strengths in optical and near-infrared for the OSUBSGS
  sample

abstract:
  We use a gravitational bar torque method to compare bar strengths (the
maximum tangential force normalized by radial force) in B and H-band images of
152 galaxies from the Ohio State University Bright Spiral Galaxy Survey. Our
main motivation is to check how much the difference in the rest-frame
wavelength could affect comparisons of bar strengths in low and high redshift
observations. Between these two bands we find an average bar strength ratio
Q_B/H= 1.25 which factor is nearly independent of the morphological type. We
show that Q_B/H > 1 is mostly due to reduced bulge dilution of radial forces in
the B-band. The bar torque method needs an estimate for the vertical scale
height of the galaxy, based on the radial scale length of the disk and the
galaxy's morphological type. Since these two might not always be possible to
determine at high redshifts in a reliable manner, we also checked that similar
results are obtained with vertical scale heights estimated from the radii
corresponding to the K-band surface brightness of 20 mag/arcsec^2. Also, we
made a simple test of the usability of the bar torque method at high redshifts
by checking the effects of image degradation (nearest neighbour sampling
without any adjustment of noise levels): we found that the estimated bar
strengths varied by +/- 10% at most as long as the total extent of the bar was
at least 10 pixels. Overall, we show that the gravitational bar torque method
should provide a proficient tool for quantifying bar strengths also at high
redshifts.


title: On the evolution and fate of supermassive stars

abstract:
  We study the evolution and fate of solar composition supermassive stars in
the mass range 60 - 1000 Msun. Our study is relevant both for very massive
objects observed in young stellar complexes as well as supermassive stars that
may potentially form through runaway stellar collisions. We predict the
outcomes of stellar evolution employing a mass-loss prescription that is
consistent with the observed Hertzsprung-Russell Diagram location of the most
massive stars. We compute a series of stellar models with an appropriately
modified version of the Eggleton evolutionary code. We find that super-massive
stars with initial masses up to 1000 Msun end their lives as objects less
massive than ~150 Msun. These objects are expected to collapse into black holes
(with M < 70 Msun) or explode as pair-instability supernovae. We argue that if
ultraluminous X-ray sources (ULXs) contain intermediate-mass black holes, these
are unlikely to be the result of runaway stellar collisions in the cores of
young clusters.


title: Low-Density Parity-Check Codes for Nonergodic Block-Fading Channels

abstract:
  We solve the problem of designing powerful low-density parity-check (LDPC)
codes with iterative decoding for the block-fading channel. We first study the
case of maximum-likelihood decoding, and show that the design criterion is
rather straightforward. Unfortunately, optimal constructions for
maximum-likelihood decoding do not perform well under iterative decoding. To
overcome this limitation, we then introduce a new family of full-diversity LDPC
codes that exhibit near-outage-limit performance under iterative decoding for
all block-lengths. This family competes with multiplexed parallel turbo codes
suitable for nonergodic channels and recently reported in the literature.


title: Connectivity of Addition Cayley Graphs

abstract:
  For any finite abelian group $G$ and any subset $S\seq G$, we determine the
connectivity of the addition Cayley graph induced by $S$ on $G$. Moreover, we
show that if this graph is not complete, then it possesses a minimum vertex cut
of a special, explicitly described form.


title: Geometric entanglement witnesses and bound entanglement

abstract:
  We study entanglement witnesses that can be constructed with regard to the
geometrical structure of the Hilbert-Schmidt space, i.e. we present how to use
these witnesses in the context of quantifying entanglement and the detection of
bound entangled states. We give examples for a particular three-parameter
family of states that are part of the \emph{magic simplex} of two-qutrit
states.


title: Higher entropic uncertainty relations for anti-commuting observables

abstract:
  Uncertainty relations lie at the very core of quantum mechanics, and form the
cornerstone of essentially all quantum cryptographic applications. In
particular, they play an important role in cryptographic protocols in the
bounded-quantum-storage model, where proving the security of all existing
protocols ultimately reduces to bounding such relations. Yet, very little is
known about such uncertainty relations for more than two measurements. Here, we
prove optimal entropic uncertainty relations for anti-commuting binary
observables for the Shannon entropy, and nearly optimal relations for the
collision entropy. Our results have immediate applications to quantum
cryptography.


title:
Heavy quark symmetry constraints on semileptonic form factors and decay
  widths of doubly heavy baryons

abstract:
  We show how heavy quark symmetry constraints on doubly heavy baryon
semileptonic decay widths can be used to test the validity of different quark
model calculations. The large discrepancies in the results observed between
different quark model approaches can be understood in terms of a severe
violation of heavy quark spin symmetry constraints by some of those models.


title: Stochastic thermodynamics: Principles and perspectives

abstract:
  Stochastic thermodynamics provides a framework for describing small systems
like colloids or biomolecules driven out of equilibrium but still in contact
with a heat bath. Both, a first-law like energy balance involving exchanged
heat and entropy production entering refinements of the second law can
consistently be defined along single stochastic trajectories. Various exact
relations involving the distribution of such quantities like integral and
detailed fluctuation theorems for total entropy production and the Jarzynski
relation follow from such an approach based on Langevin dynamics. Analogues of
these relations can be proven for any system obeying a stochastic master
equation like, in particular, (bio)chemically driven enzyms or whole reaction
networks. The perspective of investigating such relations for stochastic field
equations like the Kardar-Parisi-Zhang equation is sketched as well.


title:
Towards a non-perturbative matching of HQET and QCD with dynamical light
  quarks

abstract:
  We explain how the strategy of solving renormalization problems in HQET
non-perturbatively by a matching to QCD in finite volume can be implemented to
include dynamical fermions. As a primary application, some elements of an HQET
computation of the mass of the b-quark beyond the leading order with N_f=2 are
outlined. In particular, the matching of HQET and QCD requires relativistic QCD
simulations in a volume with L ~ 0.5 fm, which will serve to quantitatively
determine the heavy quark mass dependence of heavy-light meson observables in
the continuum limit of finite-volume two-flavour lattice QCD. As a preparation
for the latter, we report on our determination of the renormalization constants
and improvement coefficients relating the renormalized current and subtracted
bare quark mass in the relevant weak coupling region. The calculation of these
coefficients employs a constant physics condition in the Schroedinger
functional scheme, where the box size L is fixed by working at a prescribed
value of the renormalized coupling.


title: IC5063: AGN driven outflow of warm and cold gas

abstract:
  We present new ATCA 17- and 24-GHz radio images and ESO-NTT optical spectra
of the radio-loud Seyfert galaxy IC5063, the first galaxy in which a fast (~
600 km/s) outflow of neutral hydrogen was discovered. The new radio data
confirm the triple radio structure with a central core and two resolved radio
lobes. This implies that the previously detected fast outflow of neutral gas is
occurring off-nucleus, near a radio lobe about 0.5 kpc from the core. The
ionised gas shows complex kinematics in the region co-spatial with the radio
emission. Broad and blueshifted (~ 500 km/s) emission is observed in the region
of the radio lobe, at the same location as the blueshifted HI absorption. The
velocity of the ionised outflow is similar to the one found in HI. The first
order correspondence between the radio and optical properties suggests that the
outflow is driven by the interaction between the radio jet and the ISM. Despite
the high outflow velocities, no evidence is found for the ionisation of the gas
being due to fast shocks in the region of the outflow, indicating that
photoionisation from the AGN is likely to be the dominant ionisation mechanism.
The outflow rate of the warm (ionised) gas is small compared to that of the
cold gas. The mass outflow rate associated with the HI is in the same range as
for ``mild'' starburst-driven superwinds in ULIRGs. However, in IC5063, the
AGN-driven outflow appears to be limited to the inner kpc region of the galaxy.
The kinetic power associated with the HI outflow is a small fraction (a few x
10^-4) of the Eddington luminosity of the galaxy but is a significant fraction
(~ 0.1) of the nuclear bolometric luminosity. In IC5063, the outflows may have
sufficient kinetic power to have a significant impact on the evolution of the
ISM in the host galaxy.


title:
Power Efficient Scheduling under Delay Constraints over Multi-user
  Wireless Channels

abstract:
  In this paper, we consider the problem of power efficient uplink scheduling
in a Time Division Multiple Access (TDMA) system over a fading wireless
channel. The objective is to minimize the power expenditure of each user
subject to satisfying individual user delay. We make the practical assumption
that the system statistics are unknown, i.e., the probability distributions of
the user arrivals and channel states are unknown. The problem has the structure
of a Constrained Markov Decision Problem (CMDP). Determining an optimal policy
under for the CMDP faces the problems of state space explosion and unknown
system statistics. To tackle the problem of state space explosion, we suggest
determining the transmission rate of a particular user in each slot based on
its channel condition and buffer occupancy only. The rate allocation algorithm
for a particular user is a learning algorithm that learns about the buffer
occupancy and channel states of that user during system execution and thus
addresses the issue of unknown system statistics. Once the rate of each user is
determined, the proposed algorithm schedules the user with the best rate. Our
simulations within an IEEE 802.16 system demonstrate that the algorithm is
indeed able to satisfy the user specified delay constraints. We compare the
performance of our algorithm with the well known M-LWDF algorithm. Moreover, we
demonstrate that the power expended by the users under our algorithm is quite
low.


title:
Compacton-like solutions of the hydrodynamic system describing relaxing
  media

abstract:
  We show the existence of a compacton-like solutions within the relaxing
hydrodynamic-type model and perform numerical study of attracting features of
these solutions.


title:
The symmetries of five-dimensional minimal supergravity reduced to three
  dimensions

abstract:
  The 14 Killing vectors of the target space for five-dimensional minimal
supergravity reduced to three dimensions are explicitly constructed in terms of
the original field variables. These vectors generate the Lie algebra of $G_2$.
We also construct a symmetrical $7\times7$ matrix representative of the coset
$G_{2(+2)}/((SL(2,R)\times SL(2,R))$ as a function of the same fields.


title:
Effect of angular momentum distribution on gravitational loss-cone
  instability in stellar clusters around massive BH

abstract:
  Small perturbations in spherical and thin disk stellar clusters surrounding
massive a black hole are studied. Due to the black hole, stars with
sufficiently low angular momentum escape from the system through the loss cone.
We show that stability properties of spherical clusters crucially depend on
whether the distribution of stars is monotonic or non-monotonic in angular
momentum. It turns out that only non-monotonic distributions can be unstable.
At the same time the instability in disk clusters is possible for both types of
distributions.


title:
A systematic search for novae in M31 on a large set of digitized
  archival Schmidt plates

abstract:
  This paper reports on the detection of optical novae in our neighbour galaxy
M31 based on digitized historical Tautenburg Schmidt plates. The accurate
positions of the detected novae lead to a much larger database when searching
for recurrent novae in M31. We conducted a systematic search for novae on 306
digitized Tautenburg Schmidt plates covering a time span of 36 years from 1960
to 1996. From the database of both ~ 300 000 light curves and about one million
detections on only one plate per colour band, nova candidates were efficiently
selected by automated algorithms and subsequently individually inspected by
eye. We report the detection of 84 nova candidates. We found 55 nova candidates
from the automated analysis of the light curves. Among these, 22 were
previously unknown, 12 were known but not identified on Tautenburg Schmidt
plates before, and 21 novae had been previously discovered on Tautenburg
plates. An additional 29 known novae could be confirmed by the detailed
investigation of single detections. One of our newly discovered nova candidates
shows a high position coincidence with a nova detected about 30 years earlier.
Therefore, this object is likely to be a recurrent nova. Furthermore, we
re-investigated all 41 nova candidates previously found on Tautenburg plates
and confirm all but two. Positions are given for all nova candidates with a
typical accuracy of ~ 0.4 arcsec. We present light curves and finding charts as
online material. The analysis of the plates has shown the wealth of information
still buried in old plate archives. Extrapolating from this survey,
digitization of other historical M31 plate archives (e.g. from the Mount Wilson
or Asiago observatories) for a systematic nova search looks very promising.


title: Maximizing phonon thermal conductance for ballistic membranes

abstract:
  At low temperatures, phonon scattering can become so weak that phonon
transport becomes ballistic. We calculate the ballistic phonon conductance G
for membranes using elasticity theory, considering the transition from three to
two dimensions. We discuss the temperature and thickness dependence and
especially concentrate on the issue of material parameters. For all membrane
thicknesses, the best conductors have, counter-intuitively, the lowest speed of
sound.


title: The volume densities of GMCs in M81

abstract:
  HI features near young star clusters in M81 are identified as the
photodissociated surfaces of Giant Molecular Clouds (GMCs) from which the young
stars have recently formed. The HI column densities of these features show a
weak trend, from undetectable values inside R = 3.7 kpc and increasing rapidly
to values around 3 x 10^21 cm^-2 near R ~ 7.5 kpc. This trend is similar to
that of the radially-averaged HI distribution in this galaxy, and implies a
constant area covering factor of ~ 0.21 for GMCs throughout M81. The incident
UV fluxes G0 of our sample of candidate PDRs decrease radially.
  A simple equilibrium model of the photodissociation-reformation process
connects the observed values of the incident UV flux, the HI column density,
and the relative dust content, permitting an independent estimate to be made of
the total gas density in the GMC. Within the GMC this gas will be predominantly
molecular hydrogen. Volume densities of 1 < n < 200 cm^-3 are derived, with a
geometric mean of 17 cm^-3. These values are similar to the densities of GMCs
in the Galaxy, but somewhat lower than those found earlier for M101 with
similar methods. Low values of molecular density in the GMCs of M81 will result
in low levels of collisional excitation of the CO(1-0) transition, and are
consistent with the very low surface brightness of CO(1-0) emission observed in
the disk of M81.


title: The interplay between radio jets and ISM in sub-kpc radio sources

abstract:
  This paper reviews the evidence for interaction between radio jets and their
environment in small and intermediate (sub-kpc) scale radio sources.
Observations of gas (both neutral hydrogen and ionised gas) have shown the
presence of fast (> 1000 km/s) outflows likely originating from this
interaction. The characteristics of these AGN-driven outflows (e.g. mass
outflow rate) indicate that they may have a relevant impact on the evolution of
the host galaxy. We also report on the detection of large HI disks found around
the host galaxies of nearby compact radio sources. Similar structures have so
far not been detected around large radio sources. The presence of these
structures in relation to the evolution of young compact radio sources is
discussed.


title:
Signature of the interaction between dark energy and dark matter in
  galaxy clusters

abstract:
  We investigate the influence of an interaction between dark energy and dark
matter upon the dynamics of galaxy clusters. We obtain the general
Layser-Irvine equation in the presence of interactions, and find how, in that
case, the virial theorem stands corrected. Using optical, X-ray and weak
lensing data from 33 relaxed galaxy clusters, we put constraints on the
strength of the coupling in the dark sector. We find that this coupling is
small but positive, indicating that dark energy can be decaying into dark
matter.


title:
Commensurate anisotropic oscillator, SU(2) coherent states and the
  classical limit

abstract:
  We demonstrate a formally exact quantum-classical correspondence between the
stationary coherent states associated with the commensurate anisotropic
two-dimensional harmonic oscillator and the classical Lissajous orbits. Our
derivation draws upon earlier work of Louck et al [1973 \textit {J. Math.
Phys.} \textbf {14} 692] wherein they have provided a non-bijective canonical
transformation that maps, within a degenerate eigenspace, the commensurate
anisotropic oscillator on to the isotropic oscillator. This mapping leads, in a
natural manner, to a Schwinger realization of SU(2) in terms of the canonically
transformed creation and annihilation operators. Through the corresponding
coherent states built over a degenerate eigenspace, we directly effect the
classical limit via the expectation values of the underlying generators. Our
work completely accounts for the fact that the SU(2) coherent state in general
corresponds to an ensemble of Lissajous orbits.


title: Quantum Causal Networks

abstract:
  Intervention theories of causality define a relationship as causal if
appropriately specified interventions to manipulate a putative cause tend to
produce changes in the putative effect. Interventionist causal theories are
commonly formalized by using directed graphs to represent causal relationships,
local probability models to quantify the relationship between cause and effect,
and a special kind of conditioning operator to represent the effects of
interventions. Such a formal model represents a family of joint probability
distributions, one for each allowable intervention policy. This paper
interprets the von Neumann formalization of quantum theory as an
interventionist theory of causality, describes its relationship to
interventionist theories popular in the artificial intelligence literature, and
presents a new family of graphical models that extends causal Bayesian networks
to quantum systems.


title:
On the X-Ray Light Curve, Pulsed-Radio Emission, and Spin Frequency
  Evolution of the Transient Anomalous X-Ray Pulsar Xte J1810--197 During its
  X-Ray Outburst

abstract:
  We show that: (i) the long-term X-ray outburst light curve of the transient
AXP XTE J1810-197 can be accounted for by a fallback disk that is evolving
towards quiescence through a disk instability after having been heated by a
soft gamma-ray burst, (ii) the spin-frequency evolution of this source in the
same period can also be explained by the disk torque acting on the
magnetosphere of the neutron star, (iii) most significantly, recently observed
pulsed-radio emission from this source coincides with the epoch of minimum
X-ray luminosity. This is natural in terms of a fallback disk model, as the
accretion power becomes so low that it is not sufficient to suppress the beamed
radio emission from XTE J1810-197.


title: N to Delta electromagnetic and axial form factors in full QCD

abstract:
  Lattice results on the N to Delta electromagnetic, axial-vector and
pseudoscalar form factors are evaluated using dynamical staggered sea quarks
and domain wall valence quarks for pion masses in the range of 580-350 MeV, as
well as, dynamical and quenched Wilson fermions for similar pion masses.


title:
Semantic distillation: a method for clustering objects by their
  contextual specificity

abstract:
  Techniques for data-mining, latent semantic analysis, contextual search of
databases, etc. have long ago been developed by computer scientists working on
information retrieval (IR). Experimental scientists, from all disciplines,
having to analyse large collections of raw experimental data (astronomical,
physical, biological, etc.) have developed powerful methods for their
statistical analysis and for clustering, categorising, and classifying objects.
Finally, physicists have developed a theory of quantum measurement, unifying
the logical, algebraic, and probabilistic aspects of queries into a single
formalism. The purpose of this paper is twofold: first to show that when
formulated at an abstract level, problems from IR, from statistical data
analysis, and from physical measurement theories are very similar and hence can
profitably be cross-fertilised, and, secondly, to propose a novel method of
fuzzy hierarchical clustering, termed \textit{semantic distillation} --
strongly inspired from the theory of quantum measurement --, we developed to
analyse raw data coming from various types of experiments on DNA arrays. We
illustrate the method by analysing DNA arrays experiments and clustering the
genes of the array according to their specificity.

categories: math.PR cs.DB math.ST q-bio.QM stat.ML stat.TH


title: Ion trap quantum gates with amplitude-modulated laser beams

abstract:
  In ion traps, entangling gate operations can be realized by a bichromatic
pair of laser beams that collectively interact with the ions. In this paper, a
new method of modelling the laser-ion interaction is introduced that turns out
to be superior to standard techniques for the description of gate operations on
optical qubits. The treatment allows for a comparison of the performance of
gates based on $\sigma_z\otimes\sigma_z$ and M{\o}lmer-S{\o}rensen interactions
on optical transitions where the bichromatic laser field can be realized by an
amplitude-modulated laser resonant with the qubit transition. Shaping the
amplitude of the bichromatic laser pulse is shown to make the gates more robust
against experimental imperfections.


title:
Full Scale Dynamic Response of a RC Building under Weak Seismic Motions
  Using Earthquake Recordings, Ambient Vibrations and Modelling

abstract:
  In countries with a moderate seismic hazard, the classical methods developed
for strong motion prone countries to estimate the seismic behaviour and
subsequent vulnerability of existing buildings are often inadequate and not
financially realistic. The main goals of this paper are to show how the modal
analysis can contribute to the understanding of the seismic building response
and the good relevancy of a modal model based on ambient vibrations for
estimating the structural deformation under moderate earthquakes. We describe
the application of an enhanced modal analysis technique (Frequency Domain
Decomposition) to process ambient vibration recordings taken at the Grenoble
City Hall building (France). The frequencies of ambient vibrations are compared
with those of weak earthquakes recorded by the French permanent accelerometric
network (RAP) that was installed to monitor the building. The frequency
variations of the building under moderate earthquakes are shown to be slight
(~2%) and therefore ambient vibration frequencies are relevant over the elastic
domain of the building. The modal parameters extracted from ambient vibrations
are then used to determine the 1D lumped-mass model in order to reproduce the
inter-storey drift under weak earthquakes and to fix a 3D numerical model that
could be used for strong earthquakes. The correlation coefficients between data
and synthetic motion are close to 80% and 90% in horizontal directions, for the
1D and 3D modelling, respectively.


title: Study of DiMuon Rare Beauty Decays with ATLAS and CMS

abstract:
  The LHC experiments will perform sensitive tests of physics beyond the
Standard Model (BSM). The investigation of decays of beauty hadrons represents
an alternative approach in addition to direct BSM searches. The ATLAS and CMS
efforts concentrate on those B-decays that can be efficiently selected already
at the first and second level trigger. The most favorable trigger signature
will be for $B$-hadron decays with muons in the final state. Using this
trigger, ATLAS and CMS will be able to accommodate unprecedentedly high
statistics in the rare decay sector. These are purely dimuon decays, and
families of semimuonic exclusive channels. Already with data corresponding to
an integrated luminosity of \ensuremath{1 fb^{-1}}, the sensitivity in the
dimuon channels will be comparable to present measurements (world average). The
strategy is to carry on the dimuon channel program up to nominal LHC
luminosity. In particular the \ensuremath{B_s \to \mu\mu} signal with
\ensuremath{\sim}5 sigma significance can be measured combining low luminosity
\ensuremath{10^{33}cm^{-2} s^{-1}} samples with those of one year of LHC
operation at a luminosity of \ensuremath{10^{34}cm^{-2} s^{-1}


title: Binaries and the dynamical mass of star clusters

abstract:
  The total mass of a distant star cluster is often derived from the virial
theorem, using line-of-sight velocity dispersion measurements and half-light
radii, under the implicit assumption that all stars are single (although it is
known that most stars form part of binary systems). The components of binary
stars exhibit orbital motion, which increases the measured velocity dispersion,
resulting in a dynamical mass overestimation. In this article we quantify the
effect of neglecting the binary population on the derivation of the dynamical
mass of a star cluster. We find that the presence of binaries plays an
important role for clusters with total mass M < 10^5 Msun; the dynamical mass
can be significantly overestimated (by a factor of two or more). For the more
massive clusters, with Mcl > 10^5 Msun, binaries do not affect the dynamical
mass estimation significantly, provided that the cluster is significantly
compact (half-mass radius < 5 pc).


title: Diagrammatic Inference

abstract:
  Diagrammatic logics were introduced in 2002, with emphasis on the notions of
specifications and models. In this paper we improve the description of the
inference process, which is seen as a Yoneda functor on a bicategory of
fractions. A diagrammatic logic is defined from a morphism of limit sketches
(called a propagator) which gives rise to an adjunction, which in turn
determines a bicategory of fractions. The propagator, the adjunction and the
bicategory provide respectively the syntax, the models and the inference
process for the logic. Then diagrammatic logics and their morphisms are applied
to the semantics of side effects in computer languages.


title:
Crustal structure below Popocat\'epetl Volcano (Mexico) from analysis of
  Rayleigh waves

abstract:
  An array of ten broadband stations was installed on the Popocat\'epetl
volcano (Mexico) for five months between October 2002 and February 2003. 26
regional and teleseismic earthquakes were selected and filtered in the
frequency time domain to extract the fundamental mode of the Rayleigh wave. The
average dispersion curve was obtained in two steps. Firstly, phase velocities
were measured in the period range [2-50] s from the phase difference between
pairs of stations, using Wiener filtering. Secondly, the average dispersion
curve was calculated by combining observations from all events in order to
reduce diffraction effects. The inversion of the mean phase velocity yielded a
crustal model for the volcano which is consistent with previous models of the
Mexican Volcanic Belt. The overall crustal structure beneath Popocat\'epetl is
therefore not different from the surrounding area, and the velocities in the
lower crust are confirmed to be relatively low. Lateral variations of the
structure were also investigated by dividing the network into four parts and by
applying the same procedure to each sub-array. No well-defined anomalies
appeared for the two sub-arrays for which it was possible to measure a
dispersion curve. However, dispersion curves associated with individual events
reveal important diffraction for 6 s to 12 s periods which could correspond to
strong lateral variations at 5 to 10 km depth.


title:
Dynamic parameters of structures extracted from ambient vibration
  measurements: an aid for the seismic vulnerability assessment of existing
  buildings in moderate seismic hazard regions

abstract:
  During the past two decades, the use of ambient vibrations for modal analysis
of structures has increased as compared to the traditional techniques (forced
vibrations). The Frequency Domain Decomposition method is nowadays widely used
in modal analysis because of its accuracy and simplicity. In this paper, we
first present the physical meaning of the FDD method to estimate the modal
parameters. We discuss then the process used for the evaluation of the building
stiffness deduced from the modal shapes. The models considered here are 1D
lumped-mass beams and especially the shear beam. The analytical solution of the
equations of motion makes it possible to simulate the motion due to a weak to
moderate earthquake and then the inter-storey drift knowing only the modal
parameters (modal model). This process is finally applied to a 9-storey
reinforced concrete (RC) dwelling in Grenoble (France). We successfully
compared the building motion for an artificial ground motion deduced from the
model estimated using ambient vibrations and recorded in the building. The
stiffness of each storey and the inter-storey drift were also calculated.


title: D0-D0 Mixing at BaBar

abstract:
  The BaBar and Belle collaborations have recently found evidence for mixing
within the D meson system. We present some of the mixing search techniques used
by BaBar and their status as of the beginning of the summer 2007. These have
culminated in a measurement in the K decay final state of the D that is
inconsistent with the no-mixing hypothesis with a significance of 3.9 standard
deviations.


title: The nature of the light scalar mesons from their radiative decays

abstract:
  The nature of the light scalar mesons is one of the most intriguing open
challenges in hadronic spectroscopy. It is argued that radiative decays
involving these scalars can serve as an important decisive tool in establishing
their nature. In particular, special emphasis is made on the radiative decays
of the scalars themselves (in addition to the radiative decays of the phi-meson
with the scalars appearing in the final state), including their two-photon
decays. All the above mentioned processes are considered in detail in the
(point-like) kaon molecule model of the scalars and explicit predictions for
the decay widths are made. In addition, finite-range corrections to the
point-like results are investigated, with a special attention payed to gauge
invariance of the decay amplitude. Finally, the conclusion is made that
experimental data on the radiative decays with the light scalar mesons involved
strongly support the molecule assignment for the latter.


title:
Exploiting soliton decay and phase fluctuations in atom chip
  interferometry of Bose-Einstein condensates

abstract:
  We show that the decay of a soliton into vortices provides a mechanism for
measuring the initial phase difference between two merging Bose-Einstein
condensates. At very low temperatures, the mechanism is resonant, operating
only when the clouds start in anti-phase. But at higher temperatures, phase
fluctuations trigger vortex production over a wide range of initial relative
phase, as observed in recent experiments at MIT. Choosing the merge time to
maximize the number of vortices created makes the interferometer highly
sensitive to spatially varying phase patterns and hence atomic movement.


title: Shot-noise of quantum chaotic systems in the classical limit

abstract:
  Semiclassical methods can now explain many mesoscopic effects (shot-noise,
conductance fluctuations, etc) in clean chaotic systems, such as chaotic
quantum dots. In the deep classical limit (wavelength much less than system
size) the Ehrenfest time (the time for a wavepacket to spread to a classical
size) plays a crucial role, and random matrix theory (RMT) ceases to apply to
the transport properties of open chaotic systems.
  Here we summarize some of our recent results for shot-noise (intrinsically
quantum noise in the current through the system) in this deep classical limit.
For systems with perfect coupling to the leads, we use a phase-space basis on
the leads to show that the transmission eigenvalues are all 0 or 1 -- so
transmission is noiseless [Whitney-Jacquod, Phys. Rev. Lett. 94, 116801 (2005),
Jacquod-Whitney, Phys. Rev. B 73, 195115 (2006)]. For systems with
tunnel-barriers on the leads we use trajectory-based semiclassics to extract
universal (but non-RMT) shot-noise results for the classical regime [Whitney,
Phys. Rev. B 75, 235404 (2007)].


title: Measuring the spin up of the Accreting Millisecond Pulsar XTE J1751-305

abstract:
  We perform a timing analysis on RXTE data of the accreting millisecond pulsar
XTE J1751-305 observed during the April 2002 outburst. After having corrected
for Doppler effects on the pulse phases due to the orbital motion of the
source, we performed a timing analysis on the phase delays, which gives, for
the first time for this source, an estimate of the average spin frequency
derivative <nu_dot> = (3.7 +/- 1.0)E-13 Hz/s. We discuss the torque resulting
from the spin-up of the neutron star deriving a dynamical estimate of the mass
accretion rate and comparing it with the one obtained from X-ray flux.
Constraints on the distance to the source are discussed, leading to a lower
limit of \sim 6.7 kpc.


title: Spin resonance of 2D electrons in a large-area silicon MOSFET

abstract:
  We report electron spin resonance (ESR) measurements on a large-area silicon
MOSFET. An ESR signal at g-factor 1.9999(1), and with a linewidth of 0.6 G, is
observed and found to arise from two-dimensional (2D) electrons at the Si/SiO2
interface. The signal and its intensity show a pronounced dependence on applied
gate voltage. At gate voltages below the threshold of the MOSFET, the signal is
from weakly confined, isolated electrons as evidenced by the Curie-like
temperature dependence of its intensity. The situation above threshold appears
more complicated. These large-area MOSFETs provide the capability to
controllably tune from insulating to conducting regimes by adjusting the gate
voltage while monitoring the state of the 2D electron spins spectroscopically.


title: Exploring the QCD phase diagram

abstract:
  Lattice simulations employing reweighting and Taylor expansion techniques
have predicted a (\mu,T)-phase diagram according to general expectations, with
an analytic quark-hadron crossover at \mu=0 turning into a first order
transition at some critical chemical potential \mu_E. By contrast, recent
simulations using imgainary \mu followed by analytic continuation obtained a
critical structure in the {m_{u,d},m_s,T,\mu} parameter space favouring the
absence of a critical point and first order line. I review the evidence for the
latter scenario, arguing that the various raw data are not inconsistent with
each other. Rather, the discrepancy appears when attempting to extract
continuum results from the coarse (N_t=4) lattices simulated so far, and can be
explained by cut-off effects. New (as yet unpublished) data are presented,
which for N_f=3 and on N_t=4 confirm the scenario without a critical point.
Moreover, simulations on finer N_t=6 lattices show that even if there is a
critical point, continuum extrapolation moves it to significantly larger values
of \mu_E than anticipated on coarse lattices.


title:
Luminescence evidence for bulk and surface excitons in free xenon
  clusters

abstract:
  Cathodoluminescence spectra of free xenon clusters produced by condensation
of xenon-argon gas mixtures in supersonic jets expanding into vacuum were
studied. By varying initial experimental parameters, including xenon
concentration, we could obtain clusters with a xenon core (300-3500 atoms)
covered by an argon outer shell as well as shell-free xenon clusters (about
1500 atoms). The cluster size and temperature (about 40 K for both cases) were
measured electronographically. Luminescence bands evidencing the existence of
bulk and surface excitons were detected for shell-free xenon clusters. The
emission from bulk excitons in small clusters is supposed to be due to
processes of their multiple elastic reflections from the xenon-vacuum
interface. A presence of an argon shell causes extinction of the excitonic
bands. In addition, some new bands were found which have no analogs for bulk
xenon cryosamples.


title:
First results of the Noether theorem for Hopf-algebra spacetime
  symmetries

abstract:
  We summarize here the first results obtained using a technique we recently
developed for the Noether analysis of Hopf-algebra spacetime symmetries,
including the derivation of conserved charges for field theories in
noncommutative spacetimes of canonical or kappa-Minkowski type.


title:
From Bruhat intervals to intersection lattices and a conjecture of
  Postnikov

abstract:
  We prove the conjecture of A. Postnikov that (A) the number of regions in the
inversion hyperplane arrangement associated with a permutation $w\in \Sn$ is at
most the number of elements below $w$ in the Bruhat order, and (B) that
equality holds if and only if $w$ avoids the patterns 4231, 35142, 42513 and
351624. Furthermore, assertion (A) is extended to all finite reflection groups.
  A byproduct of this result and its proof is a set of inequalities relating
Betti numbers of complexified inversion arrangements to Betti numbers of closed
Schubert cells. Another consequence is a simple combinatorial interpretation of
the chromatic polynomial of the inversion graph of a permutation which avoids
the above patterns.


title:
Sensitivity of the magnetic state of a spin lattice on itinerant
  electron orbital phase

abstract:
  Spatially extended localized spins can interact via indirect exchange
interaction through Friedel oscillations in the Fermi sea. In arrays of
localized spins such interaction can lead to a magnetically ordered phase.
Without external magnetic field such a phase is well understood via a
"two-impurity" Kondo model. Here we employ non-equilibrium transport
spectroscopy to investigate the role of the orbital phase of conduction
electrons on the magnetic state of a spin lattice. We show experimentally, that
even tiniest perpendicular magnetic field can influence the magnitude of the
inter-spin magnetic exchange.


title:
Euler Characteristic of real nondegenerate tropical complete
  intersections

abstract:
  We define nondegenerate tropical complete intersections imitating the
corresponding definition in complex algebraic geometry. As in the complex
situation, all nonzero intersection multiplicity numbers between tropical
hypersurfaces defining a nondegenerate tropical complete intersection are equal
to 1. The intersection multiplicity numbers we use are sums of mixed volumes of
polytopes which are dual to cells of the tropical hypersurfaces. We show that
the Euler characteristic of a real nondegenerate tropical complete intersection
depends only on the Newton polytopes of the tropical polynomials which define
the intersection. Basically, it is equal to the usual signature of a complex
complete intersection with same Newton polytopes, when this signature is
defined. The proof reduces to the toric hypersurface case, and uses the notion
of $E$-polynomials of complex varieties.


title: Jet broadening in unstable non-Abelian plasmas

abstract:
  We perform numerical simulations of the QCD Boltzmann-Vlasov equation
including both hard elastic particle collisions and soft interactions mediated
by classical Yang-Mills fields. We provide an estimate of the coupling of jets
to a hot plasma which is independent of infrared cutoffs. For weakly-coupled
anisotropic plasmas the local rotational symmetry in momentum space is broken.
The fields develop unstable modes, forming configurations where B_t>E_t and
E_z>B_z. This provides a possible explanation for the experimental observation
that high-energy jets traversing the plasma perpendicular to the beam axis
experience much stronger broadening in rapidity than in azimuth.


title:
Quantum cohomology of minuscule homogeneous spaces III : semi-simplicity
  and consequences

abstract:
  We prove that the quantum cohomology ring of any minuscule or cominuscule
homogeneous space, specialized at q=1, is semisimple. This implies that complex
conjugation defines an algebra automorphism of the quantum cohomology ring
localized at the quantum parameter. We check that this involution coincides
with the strange duality defined in a previous paper. We deduce
Vafa-Intriligator type formulas for the Gromov-Witten invariants.


title:
Evidence of the virtual Anderson transition in a narrow impurity band of
  p-GaAs/AlGaAs quantum wells: $\epsilon_4$ conductivity and electric breakdown
  at low temperatures

abstract:
  In highly doped uncompensated p-type layers within the central part of
GaAs/AlGaAs quantum wells at low temperatures we observed an activated behavior
of the conductivity with low activation energies (1-3) meV which can not be
ascribed to standard mechanisms. We attribute this behavior to the
delocalization of hole states near the maximum of the narrow impurity band in
the sense of the Anderson transition. Low temperature conduction $\epsilon_4$
is supported by an activation of minority carriers - electrons (resulting from
a weak compensation by back-ground defects) - from the Fermi level to the band
of delocalized states mentioned above. The corresponding behavior can be
specified as virtual Anderson transition. Low temperature transport ($<4$ K)
exhibits also strong nonlinearity of a breakdown type characterized in
particular by S-shaped I-V curve. The nonlinearity is observed in unexpectedly
low fields ($<10$ V/cm). Such a behavior can be explained by a simple model
implying an impact ionization of the localized states of the minority carriers
mentioned above to the band of Anderson-delocalized states.


title:
NIR Femtosecond Control of Resonance-Mediated Generation of Coherent
  Broadband UV Emission

abstract:
  We use shaped near-infrared (NIR) pulses to control the generation of
coherent broadband ultraviolet (UV) radiation in an atomic resonance-mediated
(2+1) three-photon excitation. Experimental and theoretical results are
presented for phase controlling the total emitted UV yield in atomic sodium
(Na). Based on our confirmed understanding, we present a new simple scheme for
producing shaped femtosecond pulses in the UV/VUV spectral range using the
control over atomic resonance-mediated generation of third (or higher order)
harmonic.


title: A DC magnetic metamaterial

abstract:
  Electromagnetic metamaterials are a class of materials which have been
artificially structured on a subwavelength scale. They are currently the focus
of a great deal of interest because they allow access to previously
unrealisable properties like a negative refractive index. Most metamaterial
designs have so far been based on resonant elements, like split rings, and
research has concentrated on microwave frequencies and above. In this work, we
present the first experimental realisation of a non-resonant metamaterial
designed to operate at zero frequency. Our samples are based on a
recently-proposed template for an anisotropic magnetic metamaterial consisting
of an array of superconducting plates. Magnetometry experiments show a strong,
adjustable diamagnetic response when a field is applied perpendicular to the
plates. We have calculated the corresponding effective permeability, which
agrees well with theoretical predictions. Applications for this metamaterial
may include non-intrusive screening of weak DC magnetic fields.


title:
Axion-Dilaton Quantum String Cosmology for Flux Compactification and its
  Symmetry Breaking

abstract:
  The Wheeler-De Witt equation of type IIB quantum string cosmology
compactified with constant internal H-fluxes on a 6-torus, whose volume modulus
is frozen, is solved under the WKB approximation. The spontaneous symmetry
breaking of the S-duality group by H-fluxes is also examined.


title:
Photon pressure induced test mass deformation in gravitational-wave
  detectors

abstract:
  A widely used assumption within the gravitational-wave community has so far
been that a test mass acts like a rigid body for frequencies in the detection
band, i.e. for frequencies far below the first internal resonance. In this
article we demonstrate that localized forces, applied for example by a photon
pressure actuator, can result in a non-negligible elastic deformation of the
test masses. For a photon pressure actuator setup used in the gravitational
wave detector GEO600 we measured that this effect modifies the standard
response function by 10% at 1 kHz and about 100% at 2.5 kHz.


title:
Density functional study of the electronic and vibrational properties of
  TiOCl

abstract:
  We present the phonon spectrum of TiOCl computed using hybrid density
functional theory (DFT). A complete analysis of the spectrum is performed for
the space group Pmmn (high symmetry phase) and the space group P2_1/m (low
symmetry phase), which is the symmetry of the spin-Peierls phase. We show that
the nonlocal correlations present in the hybrid DFT approach are important for
understanding the electron-lattice interactions in TiOCl. The computed
frequencies compare well with those observed in Raman and infrared spectroscopy
experiments and we identify the origin of an anomalous phonon observed in Raman
spectroscopy. The relationship between relevant zone boundary phonons in the
high symmetry phase and the zone center counterparts in the P2_1/m symmetry
allow us to speculate about the origin of the spin-Peierls phonon.


title:
Dynamics of vortex penetration, jumpwise instabilities and nonlinear
  surface resistance of type-II superconductors in strong rf fields

abstract:
  We consider nonlinear dynamics of a single vortex in a superconductor in a
strong rf magnetic field $B_0\sin\omega t$. Using the London theory, we
calculate the dissipated power $Q(B_0,\omega)$, and the transient time scales
of vortex motion for the linear Bardeen-Stephen viscous drag force, which
results in unphysically high vortex velocities during vortex penetration
through the oscillating surface barrier. It is shown that penetration of a
single vortex through the ac surface barrier always involves penetration of an
antivortex and the subsequent annihilation of the vortex antivortex pairs.
Using the nonlinear Larkin-Ovchinnikov (LO) viscous drag force at higher vortex
velocities $v(t)$ results in a jump-wise vortex penetration through the surface
barrier and a significant increase of the dissipated power. We calculate the
effect of dissipation on nonlinear vortex viscosity $\eta(v)$ and the rf vortex
dynamics and show that it can also result in the LO-type behavior,
instabilities, and thermal localization of penetrating vortex channels. We
propose a thermal feedback model of $\eta(v)$, which not only results in the LO
dependence of $\eta(v)$ for a steady-state motion, but also takes into account
retardation of temperature field around rapidly accelerating vortex, and a
long-range interaction with the surface. We also address the effect of pinning
on the nonlinear rf vortex dynamics and the effect of trapped magnetic flux on
the surface resistance $R_s$ calculated as a function or rf frequency and
field. It is shown that trapped flux can result in a temperature-independent
residual resistance $R_i$ at low $T$, and a hysteretic low-field dependence of
$R_i(B_0)$, which can {\it decrease} as $B_0$ is increased, reaching a minimum
at $B_0$ much smaller than the thermodynamic critical field $B_c$.


title:
A Canonical Quadratic Form on the Determinant Line of a Flat Vector
  Bundle

abstract:
  We introduce and study a canonical quadratic form, called the torsion
quadratic form, of the determinant line of a flat vector bundle over a closed
oriented odd-dimensional manifold. This quadratic form caries less information
than the refined analytic torsion, introduced in our previous work, but is
easier to construct and closer related to the combinatorial Farber-Turaev
torsion. In fact, the torsion quadratic form can be viewed as an analytic
analogue of the Poincare-Reidemeister scalar product, introduced by Farber and
Turaev. Moreover, it is also closely related to the complex analytic torsion
defined by Cappell and Miller and we establish the precise relationship between
the two. In addition, we show that up to an explicit factor, which depends on
the Euler structure, and a sign the Burghelea-Haller complex analytic torsion,
whenever it is defined, is equal to our quadratic form. We conjecture a formula
for the value of the torsion quadratic form at the Farber-Turaev torsion and
prove some weak version of this conjecture. As an application we establish a
relationship between the Cappell-Miller and the combinatorial torsions.


title: Dynamics of Domain Walls for Split and Runaway Potentials

abstract:
  We demonstrate that the evolution of wall-like inhomogeneities in run-away
potentials, characteristic of dynamical supersymmetry breaking and moduli
stabilisation, is very similar to the evolution of domain wall networks
associated with double well potentials. Instabilities that would lead to a
rapid decay of domain walls can be significantly ameliorated by compensation
effects between a non-degeneracy of the vacua and a biased initial
distribution, which can be naturally expected in a wide class or particle
physics models that lead to out-of-equilibrium phase transitions. Within this
framework, it is possible to obtain domain walls that live long enough to be
relevant for the cosmic power spectrum and galaxy clustering, while being
compatible with the observed cosmic microwave background anisotropies.


title: Hamming Distance for Conjugates

abstract:
  Let x, y be strings of equal length. The Hamming distance h(x,y) between x
and y is the number of positions in which x and y differ. If x is a cyclic
shift of y, we say x and y are conjugates. We consider f(x,y), the Hamming
distance between the conjugates xy and yx. Over a binary alphabet f(x,y) is
always even, and must satisfy a further technical condition. By contrast, over
an alphabet of size 3 or greater, f(x,y) can take any value between 0 and
|x|+|y|, except 1; furthermore, we can always assume that the smaller string
has only one type of letter.


title: Large diamagnetic persistent currents

abstract:
  In multichannel rings, evanescent modes will always co-exist with propagating
modes. The evanescent modes can carry a very large diamagnetic persistent
current that can oscillate with energy and are very sensitive to impurity
scattering. This provides a natural explanation for the large diamagnetic
persistent currents observed in experiments.


title: Detection of Spin Correlations in Optical Lattices by Light Scattering

abstract:
  We show that spin correlations of atoms in an optical lattice can be
reconstructed by coupling the system to the light, and by measuring
correlations between the emitted photons. This principle is the basis for a
method to characterize states in quantum computation and simulation with
optical lattices. As examples, we study the detection of spin correlations in a
quantum magnetic phase, and the characterization of cluster states.


title:
On the computation of Galois representations associated to level one
  modular forms

abstract:
  In this paper we explicitly compute mod-l Galois representations associated
to modular forms. To be precise, we look at cases with l<=23 and the modular
forms considered will be cusp forms of level 1 and weight up to 22. We present
the result in terms of polynomials associated to the projectivised
representations. As an application, we will improve a known result on Lehmer's
non-vanishing conjecture for Ramanujan's tau function.


title:
Field-tunable magnetic phases in a semiconductor-based two-dimensional
  Kondo lattice

abstract:
  We show the existence of intrinsic localized spins in mesoscopic
high-mobility GaAs/AlGaAs heterostructures. Non-equilibrium transport
spectroscopy reveals a quasi-regular distribution of the spins, and indicates
that the spins interact indirectly via the conduction electrons. The
interaction between spins manifests in characteristic zero-bias anomaly near
the Fermi energy, and indicates gate voltage-controllable magnetic phases in
high-mobility heterostructures. To address this issue further, we have also
designed electrostatically tunable Hall devices, that allow a probing of Hall
characteristics at the active region of the mesoscopic devices. We show that
the zero field Hall coefficient has an anomalous contribution, which can be
attributed to scattering by the localized spins. The anomalous contribution can
be destroyed by an increase in temperature, source drain bias, or field range.


title: On Connections between the Quantum and Hydrodynamical Pictures of Matter

abstract:
  We present a general, model-independent, quantum statistical treatment of the
connection between the quantum and hydrodynamical pictures of reservoir driven
macroscopic systems. This treatment is centred on the large scale properties of
locally conserved hydrodynamical observables and is designed to form a bridge
between quantum microdynamics and classical macroscopic continuum mechanics,
rather than a derivation of the latter from the former. The key assumptions on
which the treatment is based are hypotheses of chaoticity and local equilibrium
for the hydrodynamical fluctuations around nonequilibrium steady states,
together with an extension of Onsager's regrssion hypothesis to those states.
On this basis, we establish canonical generalisations of both the Onsager
reciprocity relations and the Onsager-Machlup fluctuation theory to
nonequilibrium steady states, and we show that the spatial correlations of the
hydrodynamical fluctuations are generically of long range in these states.

categories: math-ph cond-mat.stat-mech math.MP quant-ph


title:
Electroformation in a flow chamber with solution exchange as a means of
  preparation of flaccid giant vesicles

abstract:
  A recently described technique (Estes and Mayer, Biochim. Biophys. Acta 1712
(2005) 152--160) for the preparation of giant unilamellar vesicles (GUVs) in
solutions with high ionic strength is examined. By observing a series of
osmotic swellings followed by vesicle bursts upon a micropipette transfer of a
single POPC GUV from a sucrose solution into an isoosmolar glycerol solution, a
value for the permeability of POPC membrane for glycerol, P = (2.09+/-0.82) x
10^{-8} m/s, has been obtained. Based on this result, an alternative mechanism
is proposed for the observed exchange of vesicle interior. With modifications,
the method of Estes and Mayer is then applied to preparation of flaccid GUVs.


title: The Debye-Waller factor of stabilized delta-Pu

abstract:
  The Debye-Waller factor has been calculated for stabilized delta-phase
plutonium with 5% aluminum. A quasi-harmonic Born-von Karman force model with
temperature dependent phonon frequencies was used to calculate the mean-square
thermal atomic displacement from absolute zero to 800 K. Implementation of the
observed anomalous softening of the long wavelength phonons with increasing
temperature cannot account for the softening of the measured thermal parameter
at high temperatures nor for its rather high value at low temperatures. The
implications for diffraction measurements on delta-phase stabilized plutonium
alloys are discussed.


title: What Have Spacetime, Shape and Symmetry to Do with Thermodynamics?

abstract:
  Some highly speculative and serendipitous ideas that might relate
thermodynamics, spacetime, shape and symmetry are brought together. A
hypothetical spacetime comprising a pointwise lattice with a fixed metric is
considered. If there were absolute symmetry between displacement and time it is
suggested that the velocity of light would be an integer conversion factor
between the units of these quantities. In the context of such outlandish
hypotheses the answer to the question posed would be 'everything'.


title: A Detailed Study of 2S 0114+650 with the RXTE

abstract:
  We present the results of a detailed study of the high mass X-ray binary 2S
0114+650 made with the pointed instruments onboard the Rossi X-ray Timing
Explorer. The spectral and temporal behaviour of this source was examined over
the pulse, orbital, and super-orbital timescales, covering $\sim$2 cycles of
the 30.7 d super-orbital modulation. Marginal evidence for variability of the
power law photon index over the pulse period was identified, similar to that
observed from other X-ray pulsars. If this variability is real it can be
attributed to a varying viewing geometry of the accretion region with the spin
of the neutron star. Variability of the neutral hydrogen column density over
the orbital period was observed, which we attribute to the line of sight motion
of the neutron star through the dense circumstellar environment. A reduction in
the power law photon index was observed during the orbital maximum, which we
speculate is due to absorption effects as the neutron star passes behind a
heavily absorbing region near the base of the supergiant companion's wind. No
significant variability of the column density was observed over the
super-orbital period, indicating that variable obscuration by a precessing warp
in an accretion disc is not the mechanism behind the super-orbital modulation.
In contrast, a significant increase in the power law photon index was observed
during the super-orbital minimum. We conclude that the observed super-orbital
modulation is tied to variability in the mass accretion rate due to some as yet
unidentified mechanism.


title: The Three-Dimensional Behavior of Spiral Shocks in Protoplanetary Disks

abstract:
  In this dissertation, I describe theoretical and numerical studies that
address the three-dimensional behavior of spiral shocks in protoplanetary disks
and the controversial topic of gas giant formation by disk instability. For
this work, I discuss characteristics of gravitational instabilities (GIs) in
bursting and asymptotic phase disks; outline a theory for the three-dimensional
structure of spiral shocks, called shock bores, for isothermal and adiabatic
gases; consider convection as a source of cooling for protoplanetary disks;
investigate the effects of opacity on disk cooling; use multiple analyses to
test for disk stability against fragmentation; test the sensitivity of GI
behavior to radiation boundary conditions; measure shock strengths and
frequencies in GI-bursting disks; evaluate temperature fluctuations in unstable
disks; and investigate whether spiral shocks can form chondrules when GIs
activate. The numerical methods developed for these studies are discussed,
including a radiation transport routine that explicitly couples the low and
high optical depth regimes and a routine that models ortho and parahydrogen.
Finally, I explore the hypothesis that chondrule formation and the FU Ori
phenomenon are driven by GI activation in dead zones.


title:
Spectroscopy of strontium Rydberg states using electromagnetically
  induced transparency

abstract:
  We report on the all-optical detection of Rydberg states in a effusive atomic
beam of strontium atoms using electromagnetically induced transparency (EIT).
Using narrow-linewidth CW lasers we obtain an EIT linewidth of 5 MHz. To
illustrate the high spectroscopic resolution offered by this method, we have
measured isotope shifts of the 5s18d ^1D_2 and 5s19s ^1S_0 Rydberg states. This
technique could be applied to high-resolution, non-destructive measurements of
ultra-cold Rydberg gases and plasmas.


title:
Growth rates of the Weibel and tearing mode instabilities in a
  relativistic pair plasma

abstract:
  We present an algorithm for solving the linear dispersion relation in an
inhomogeneous, magnetised, relativistic plasma. The method is a generalisation
of a previously reported algorithm that was limited to the homogeneous case.
The extension involves projecting the spatial dependence of the perturbations
onto a set of basis functions that satisfy the boundary conditions (spectral
Galerkin method). To test this algorithm in the homogeneous case, we derive an
analytical expression for the growth rate of the Weibel instability for a
relativistic Maxwellian distribution and compare it with the numerical results.
In the inhomogeneous case, we present solutions of the dispersion relation for
the relativistic tearing mode, making no assumption about the thickness of the
current sheet, and check the numerical method against the analytical
expression.


title:
Quasiparticle evolution and pseudogap formation in V2O3: An infrared
  spectroscopy study

abstract:
  The infrared conductivity of V2O3 is measured in the whole phase diagram.
Quasiparticles appear above the Neel temperature TN and eventually disappear
further enhancing the temperature, leading to a pseudogap in the optical
spectrum above 425 K. Our calculations demonstrate that this loss of coherence
can be explained only if the temperature dependence of lattice parameters is
considered. V2O3 is therefore effectively driven from the metallic to the
insulating side of the Mott transition as the temperature is increased.


title:
Realization of abstract convex geometries by point configurations, Part
  1

abstract:
  The Edelman-Jamison problem is to characterize those abstract convex
geometries that are representable by a set of points in the plane. We show that
some natural modification of the Edelman-Jamison problem is equivalent to the
well known NP-hard order type problem.


title:
Dynamically correlated regions and configurational entropy in
  supercooled liquids

abstract:
  When a liquid is cooled below its melting temperature, if crystallization is
avoided, it forms a glass. This phenomenon, called glass transition, is
characterized by a marked increase of viscosity, about 14 orders of magnitude,
in a narrow temperature interval. The microscopic mechanism behind the glass
transition is still poorly understood. However, recently, great advances have
been made in the identification of cooperative rearranging regions, or
dynamical heterogeneities, i.e. domains of the liquid whose relaxation is
highly correlated. The growth of the size of these domains is now believed to
be the driving mechanism for the increase of the viscosity. Recently a tool to
quantify the size of these domains has been proposed. We apply this tool to a
wide class of materials to investigate the correlation between the size of the
heterogeneities and their configurational entropy, i.e. the number of states
accessible to a correlated domain. We find that the relaxation time of a given
system, apart from a material dependent pre-factor, is a universal function of
the configurational entropy of a correlated domain. As a consequence, we find
that at the glass transition temperature, the size of the domains and the
configurational entropy per unit volume are anti-correlated, as originally
predicted by the Adam-Gibbs theory. Finally, we use our data to extract some
exponents defined in the framework of the Random First Order Theory, a recent
quantitative theory of the glass transition.


title: Quantum-dot thermometry

abstract:
  We present a method for the measurement of a temperature differential across
a single quantum dot that has transmission resonances that are separated in
energy by much more than the thermal energy. We determine numerically that the
method is accurate to within a few percent across a wide range of parameters.
The proposed method measures the temperature of the electrons that enter the
quantum dot and will be useful in experiments that aim to test theory which
predicts quantum dots are highly-efficient thermoelectrics.


title:
Biconical structures in two-dimensional anisotropic Heisenberg
  antiferromagnets

abstract:
  Square lattice Heisenberg and XY antiferromagnets with uniaxial anisotropy in
a field along the easy axis are studied. Based on ground state considerations
and Monte Carlo simulations, the role of biconical structures in the transition
region between the antiferromagnetic and spin--flop phases is analyzed. In
particular, adding a single--ion anisotropy to the XXZ antiferromagnet, one
observes, depending on the sign of that anisotropy, either an intervening
biconical phase or a direct transition of first order separating the two
phases. In case of the anisotropic XY model, the degeneracy of the ground
state, at a critical field, in antiferromagnetic, spin--flop, and bidirectional
structures seems to result, as in the case of the XXZ model, in a narrow
disordered phase between the antiferromagnetic and spin--flop phases, dominated
by bidirectional fluctuations.


title: Estimates on trapped modes in deformed quantum layers

abstract:
  We use a logarithmic Lieb-Thirring inequality for two-dimensional
Schroedinger operators and establish estimates on trapped modes in
geometrically deformed quantum layers.


title: The forgetful map in rational K-theory

abstract:
  Let G be a connected reductive algebraic group acting on a scheme X. Let R(G)
denote the representation ring of G, and let I be the ideal in R(G) of virtual
representations of rank 0. Let G(X) (resp. G(G,X)) denote the Grothendieck
group of coherent sheaves (resp. G-equivariant coherent sheaves) on X.
Merkurjev proved that if the fundamental group of G is torsion-free, then the
map of G(G,X)/IG(G,X) to G(X) is an isomorphism. Although this map need not be
an isomorphism if the fundamental group of G has torsion, we prove that without
the assumption on the fundamental group of G, this map is an isomorphism after
tensoring with the rational numbers.


title: A Group Theoretic Model for Information

abstract:
  In this paper we formalize the notions of information elements and
information lattices, first proposed by Shannon. Exploiting this formalization,
we identify a comprehensive parallelism between information lattices and
subgroup lattices. Qualitatively, we demonstrate isomorphisms between
information lattices and subgroup lattices. Quantitatively, we establish a
decisive approximation relation between the entropy structures of information
lattices and the log-index structures of the corresponding subgroup lattices.
This approximation extends the approximation for joint entropies carried out
previously by Chan and Yeung. As a consequence of our approximation result, we
show that any continuous law holds in general for the entropies of information
elements if and only if the same law holds in general for the log-indices of
subgroups. As an application, by constructing subgroup counterexamples we find
surprisingly that common information, unlike joint information, obeys neither
the submodularity nor the supermodularity law. We emphasize that the notion of
information elements is conceptually significant--formalizing it helps to
reveal the deep connection between information theory and group theory. The
parallelism established in this paper admits an appealing group-action
explanation and provides useful insights into the intrinsic structure among
information elements from a group-theoretic perspective.