title:
Reentrant and Forward Phase Diagrams of the Anisotropic
  Three-Dimensional Ising Spin Glass

abstract:
  The spatially uniaxially anisotropic d=3 Ising spin glass is solved exactly
on a hierarchical lattice. Five different ordered phases, namely ferromagnetic,
columnar, layered, antiferromagnetic, and spin-glass phases, are found in the
global phase diagram. The spin-glass phase is more extensive when randomness is
introduced within the planes than when it is introduced in lines along one
direction. Phase diagram cross-sections, with no Nishimori symmetry, with
Nishimori symmetry lines, or entirely imbedded into Nishimori symmetry, are
studied. The boundary between the ferromagnetic and spin-glass phases can be
either reentrant or forward, that is either receding from or penetrating into
the spin-glass phase, as temperature is lowered. However, this boundary is
always reentrant when the multicritical point terminating it is on the
Nishimori symmetry line.


title:
The Richness and Beauty of the Physics of Cosmological Recombination:
  The Contributions from Helium

abstract:
  The physical ingredients to describe the epoch of cosmological recombination
are amazingly simple and well-understood. This fact allows us to take into
account a very large variety of processes, still finding potentially measurable
consequences. In this contribution we highlight some of the detailed physics
that were recently studied in connection with cosmological hydrogen and helium
recombination. The impact of these considerations is two-fold: (i) the
associated release of photons during this epoch leads to interesting and unique
deviations of the Cosmic Microwave Background (CMB) energy spectrum from a
perfect blackbody, which, in particular at decimeter wavelength, may become
observable in the near future. Despite the fact that the abundance of helium is
rather small, it also contributes a sizeable amount of photons to the full
recombination spectrum, which, because of differences in the dynamics of the
helium recombinations and the non-trivial superposition of all components, lead
to additional distinct spectral features. Observing the spectral distortions
from the epochs of hydrogen and helium recombination, in principle would
provide an additional way to determine some of the key parameters of the
Universe (e.g. the specific entropy, the CMB monopole temperature and the
pre-stellar abundance of helium), not suffering from limitations set by cosmic
variance. Also it permits us to confront our detailed understanding of the
recombination process with direct observational evidence. (ii) with the advent
of high precision CMB data, e.g. as will be available using the Planck Surveyor
or CMBpol, a very accurate theoretical understanding of the ionization history
of the Universe becomes necessary for the interpretation of the CMB temperature
and polarization anisotropies. (abridged)


title:
First Stereoscopic Coronal Loop Reconstructions from Stereo Secchi
  Images

abstract:
  We present the first reconstruction of the three-dimensional shape of
magnetic loops in an active region from two different vantage points based on
simultaneously recorded images. The images were taken by the two EUVI
telescopes of the SECCHI instrument onboard the recently launched STEREO
spacecraft when the heliocentric separation of the two space probes was 12
degrees. We demostrate that these data allow to obtain a reliable
three-dimensional reconstruction of sufficiently bright loops. The result is
compared with field lines derived from a coronal magnetic field model
extrapolated from a photospheric magnetogram recorded nearly simultaneously by
SOHO/MDI. We attribute discrepancies between reconstructed loops and
extrapolated field lines to the inadequacy of the linear force-free field model
used for the extrapolation.


title:
Integral field spectroscopy of planetary nebulae: mapping the line
  diagnostics and hydrogen-poor zones with VLT FLAMES

abstract:
  (Abridged) Results from the first dedicated study of Galactic PNe by means of
optical integral field spectroscopy with the VLT FLAMES Argus IFU are
presented. Three typical Galactic-disk PNe have been mapped with the
11.5''x7.2'' Argus array: two dimensional spectral maps of NGC 5882, 6153 and
7009 with 297 spatial pixels per target were obtained at sub-arcsec resolutions
and 297 spectra per target were obtained in the 396.4-507.8 nm range. Spatially
resolved maps of emission lines and of nebular physical properties were
produced. The abundances of helium and of doubly ionized carbon and oxygen were
derived from optical recombination lines (ORLs), while those of O^2+ were also
derived from the collisionally excited lines (CELs). The abundance discrepancy
problem was investigated by mapping the ratio of ORL/CEL abundances for O^2+
(the abundance discrepancy factor; ADF) across the face of the PNe. The ADF
varies between targets and also with position within the targets attaining
values of ~40 in the case of NGC 6153. Correlations of the ADF with geometric
distance from the nucleus, as well as with [O III] electron temperature, plasma
ionization state and other physical properties are established. Very small
values of the temperature fluctuation parameter in the plane of the sky are
found in all cases. It is argued that these results provide further evidence
for the existence in typical PNe of a distinct nebular component consisting of
hydrogen-deficient plasma. The zones containing this posited component appear
as undulations in the C II and C II ORL abundance diagnostics of about 2
spatial pixels across; any associated structures should have physical sizes of
less than ~1000 astronomical units. We propose that circumstellar disks, Abell
30-type knots, or Helix-type cometary globules may be involved.


title:
Mesonic quasinormal modes of the Sakai-Sugimoto model at high
  temperature

abstract:
  We examine the mesonic thermal spectrum of the Sakai-Sugimoto model of
holographic QCD by finding the quasinormal frequencies of the supergravity
dual. If flavour is added using D8 and anti-D8 branes there exist embeddings
where the D-brane worldvolume contains a black hole. For these embeddings (the
high-temperature phase of the Sakai-Sugimoto model) we determine the
quasinormal spectra of scalar and vector mesons arising from the worldvolume
DBI action of the D-brane. We stress the importance of a coordinate change that
makes the in-falling quasinormal modes regular at the horizon allowing a simple
numerical shooting technique. Finally we examine the effect of finite spatial
momentum on quasinormal spectra.


title:
Distributed Compression for the Uplink of a Backhaul-Constrained
  Coordinated Cellular Network

abstract:
  We consider a backhaul-constrained coordinated cellular network. That is, a
single-frequency network with $N+1$ multi-antenna base stations (BSs) that
cooperate in order to decode the users' data, and that are linked by means of a
common lossless backhaul, of limited capacity $\mathrm{R}$. To implement
receive cooperation, we propose distributed compression: $N$ BSs, upon
receiving their signals, compress them using a multi-source lossy compression
code. Then, they send the compressed vectors to a central BS, which performs
users' decoding. Distributed Wyner-Ziv coding is proposed to be used, and is
optimally designed in this work. The first part of the paper is devoted to a
network with a unique multi-antenna user, that transmits a predefined Gaussian
space-time codeword. For such a scenario, the compression codebooks at the BSs
are optimized, considering the user's achievable rate as the performance
metric. In particular, for $N = 1$ the optimum codebook distribution is derived
in closed form, while for $N>1$ an iterative algorithm is devised. The second
part of the contribution focusses on the multi-user scenario. For it, the
achievable rate region is obtained by means of the optimum compression
codebooks for sum-rate and weighted sum-rate, respectively.


title: Quantum Deformations of the One-Dimensional Hubbard Model

abstract:
  The centrally extended superalgebra psu(2|2)xR^3 was shown to play an
important role for the integrable structures of the one-dimensional Hubbard
model and of the planar AdS/CFT correspondence. Here we consider its quantum
deformation U_q(psu(2|2)xR^3) and derive the fundamental R-matrix. From the
latter we deduce an integrable spin chain Hamiltonian with three independent
parameters and the corresponding Bethe equations to describe the spectrum on
periodic chains. We relate our Hamiltonian to a two-parametric Hamiltonian
proposed by Alcaraz and Bariev which can be considered a quantum deformation of
the one-dimensional Hubbard model.


title: Transient nearest neighbor random walk and Bessel process

abstract:
  We prove strong invariance principle between a transient Bessel process and a
certain nearest neighbor (NN) random walk that is constructed from the former
by using stopping times. It is also shown that their local times are close
enough to share the same strong limit theorems. It is shown furthermore, that
if the difference between the distributions of two NN random walks are small,
then the walks themselves can be constructed so that they are close enough.
Finally, some consequences concerning strong limit theorems are discussed.


title:
Broadening and intensity redistribution in the Na($3p$) hyperfine
  excitation spectra due to optical pumping in the weak excitation limit

abstract:
  Detailed analysis of spectral line broadening and variations in relative
intensities of hyperfine spectral components due to optical pumping is
presented. Hyperfine levels of sodium $3p_{1/2}$ and $3p_{3/2}$ levels are
selectively excited in a supersonic beam at various laser intensities under the
conditions when optical pumping time is shorter than transit time of atoms
through the laser beam. The excitation spectra exhibit significant line
broadening at laser intensities well below the saturation intensity, and
redistribution of intensities of hyperfine spectral components is observed,
which in some cases is contradicting with intuitive expectations. Theoretical
analysis of the dynamics of optical pumping shows that spectral line broadening
depends sensitively on branching coefficient of the laser-driven transition.
Analytical expressions for branching ratio dependent critical Rabi frequency
and critical laser intensity are derived, which give the threshold for onset of
noticeable line broadening by optical pumping. Transitions with larger and
smaller branching coefficients are relatively less affected. The theoretical
excitation spectra were calculated numerically by solving density matrix
equations of motion using the split propagation technique, and they well
reproduce the observed effects of line broadening and peak intensity
variations. The calculations also show that presence of dark (i.e., not laser-
coupled) Zeeeman sublevels in the lower state results in effective branching
coefficients which vary with laser intensity and differ from those implied by
the sum rules, and this can lead to peculiar changes in peak ratios of
hyperfine components of the spectra.


title: Variational wave functions for homogenous Bose systems

abstract:
  We study variational wave functions of the product form, factorizing
according to the wave vectors k, for the ground state of a system of bosons
interacting via positive pair interactions with a positive Fourier transform.
Our trial functions are members of different orthonormal bases in Fock space.
Each basis contains a quasiparticle vacuum state and states with an arbitrary
finite number of quasiparticles. One of the bases is that of Valatin and Butler
(VB), introduced fifty years ago and parametrized by an infinite set of
variables determining Bogoliubov's canonical transformation for each k. In
another case, inspired by Nozi\`eres and Saint James the canonical
transformation for k=0 is replaced by a shift in the creation/annihilation
operators. For the VB basis we prove that the lowest energy is obtained in a
state with ~sqrt{volume} quasiparticles in the zero mode. The number of k=0
physical particles is of the order of the volume and its fluctuation is
anomalously large, resulting in an excess energy. The same fluctuation is
normal in the second type of optimized bases, the minimum energy is smaller and
is attained in a vacuum state. Associated quasiparticle theories and questions
about the gap in their spectrum are also discussed.


title: Quantum information splitting using multi-partite cluster states

abstract:
  We provide various schemes for the splitting up of Quantum information into
parts using the four and five partite cluster states. Explicit protocols for
the Quantum information splitting (QIS) of single and two qubit states are
illustrated. It is found that the four partite cluster state can be used for
the QIS of an entangled state and the five partite cluster state can be used
for QIS of an arbitrary two qubit state. The schemes considered here are also
secure against certain eavesdropping attacks.


title: Impedance-matched microwave lens

abstract:
  A microwave lens with highly reduced reflectance, as compared to conventional
dielectric lenses, is proposed. The lens is based on two-dimensional or
three-dimensional transmission-line networks that can be designed to have an
effective refractive index larger than one, while having almost perfect
impedance matching with free space. The design principles are presented and an
example lens is studied using commercial simulation software.


title: On mode conversion and wave reflection in magnetic Ap stars

abstract:
  We investigate the effect of a strong large scale magnetic field on the
reflection of high frequency acoustic modes in rapidly oscillating Ap stars. To
that end we consider a toy model composed of an isothermal atmosphere matched
onto a polytropic interior and determine the numerical solution to the set of
ideal magneto-hydrodynamic equations in a local plane-parallel approximation
with constant gravity. Using the numerical solution in combination with
approximate analytical solutions that are valid in the limits where the
magnetic and acoustic components are decoupled, we calculate the relative
fraction of energy flux that is carried away in each oscillation cycle by
running acoustic waves in the atmosphere and running magnetic waves in the
interior. For oscillation frequencies above the acoustic cutoff we show that
most energy losses associated with the presence of running waves occur in
regions where the magnetic field is close to vertical. Moreover, by considering
the depth dependence of the energy associated with the magnetic component of
the wave in the atmosphere we show that a fraction of the wave energy is kept
in the oscillation every cycle. For frequencies above the acoustic cutoff
frequency such energy is concentrated in regions where the magnetic field is
significantly inclined in relation to the local vertical. Even though our
calculations were aimed at studying oscillations with frequencies above the
acoustic cutoff frequency, based on our results we discuss what results may be
expected for oscillations of lower frequency.


title: Magnetized static black Saturn

abstract:
  We construct a new static solution to the 5D Einstein-Maxwell equations
describing a static black hole surrounded by a non-rotating dipole black ring.
The configuration is kept in equilibrium by an external magnetic field
interacting with the dipole charge of the black ring. The properties of the
black Saturn-like configuration are studied and the basic physical quantities
are calculated. The solution demonstrates 2-fold continuous non-uniqueness of
the 5D magnetized static neutral black objects for fixed total mass and Melvin
background.


title:
Stabilizing and Destabilizing Effects of Embedding 3-node Subgraphs on
  State Space of Boolean Networks

abstract:
  We demonstrate the effects of embedding subgraphs using a Boolean network,
which is one of the discrete dynamical models for transcriptional regulatory
networks. After comparing the dynamical properties of network embedded seven
different subgraphs including feedback and feedforward subgraphs, we found that
complexity of the state space that increases with longer length of attractors
and greater number of attractors is reduced for networks with more feedforward
subgraphs. In addition, feedforward subgraphs can also provide higher mutual
information with lower entropy in a temporal program of gene expression.
Networks with other six subgraphs show opposite effects on dynamics of the
networks, is roughly consistent with Thomas's conjecture. These results suggest
that feedforward subgraphs are one of the favorable local structures in
biological complex networks.


title: Chiral Symmetry in Nuclei -- Theoretical Expectations and Hard Facts

abstract:
  It is widely believed that chiral symmetry is restored not only at high
temperatures, but also at high nuclear densities. The drop of the order
parameter of the chiral phase transition, the chiral condensate, with density
has indeed been calculated in various models and is as such a rather robust
result. In this talk I point out that the connection of this property with
actual observables is far less clear. For this task a good hadronic description
of the primary production of hadrons, their propagation inside the nuclear
medium, their decay and the propagation of the decay products through the
medium to the detector all have to be treated with equal accuracy and weight.
In this talk I illustrate with the examples of $\omega$ production and
$\pi^0\pi^0$ production how important in particular final state interactions
are.


title: Long Gamma-Ray Bursts and Their Host Galaxies at High Redshift

abstract:
  Motivated by the recent observational and theoretical evidence that long
Gamma-Ray Bursts (GRBs) are likely associated with low metallicity, rapidly
rotating massive stars, we examine the cosmological star formation rate (SFR)
below a critical metallicity Z_crit Z_sun/10 - Z_sun/5, to estimate the event
rate of high-redshift long GRB progenitors. To this purpose, we exploit a
galaxy formation scenario already successfully tested on a wealth of
observational data on (proto)spheroids, Lyman break galaxies, Lyman alpha
emitters, submm galaxies, quasars, and local early-type galaxies. We find that
the predicted rate of long GRBs amounts to about 300 events/yr/sr, of which
about 30 per cent occur at z>~6. Correspondingly, the GRB number counts well
agree with the bright SWIFT data, without the need for an intrinsic luminosity
evolution. Moreover, the above framework enables us to predict properties of
the GRB host galaxies. Most GRBs are associated with low mass galaxy halos
M_H<~10^11 M_sun, and effectively trace the formation of small galaxies in such
halos. The hosts are young, with age smaller than 5*10^7 yr, gas rich, but
poorly extincted (A_V<~0.1) because of their chemical immaturity; this also
implies high specific SFR and quite extreme alpha-enhancement. Only the
minority of hosts residing in large halos with M_H>~10^12 M_sun have larger
extinction (A_V~0.7-1), SFRs exceeding 100 M_sun/yr and can be detected at
submm wavelengths. Most of the hosts have UV magnitudes in the range -20
<~M_1350<~ -16, and Lyman alpha luminosity in the range 2*10^40
<~L_Lya<~2*10^42 erg/s. GRB hosts are thus tracing the faint end of the
luminosity function of Lyman break galaxies and Lyman alpha emitters.


title:
Quasi-normal modes of spherically symmetric black hole spacetimes with
  cosmic string in a Dirac field

abstract:
  Dirac equation for a general black hole metric having a cosmic string is
derived. The quasi-normal mode frequencies for Schwarzschild, RN extremal, SdS
and near extremal SdS black hole space-times with cosmic string perturbed by a
massless Dirac field are obtained using WKB approximation and found that in all
these cases, decay is less in black holes having cosmic string compared to
black holes with out string.


title:
Weighted norm inequalities for de Branges--Rovnyak spaces and their
  applications

abstract:
  Let $\mathcal{H}(b)$ denote the de Branges--Rovnyak space associated with a
function $b$ in the unit ball of $H^\infty(\mathbb{C}_+)$. We study the
boundary behavior of the derivatives of functions in $\mathcal{H}(b)$ and
obtain weighted norm estimates of the form $\|f^{(n)}\|_{L^2(\mu)} \le
C\|f\|_{\mathcal{H}(b)}$, where $f \in \mathcal{H}(b)$ and $\mu$ is a
Carleson-type measure on $\mathbb{C}_+\cup\mathbb{R}$. We provide several
applications of these inequalities. We apply them to obtain embedding theorems
for $\mathcal{H}(b)$ spaces. These results extend Cohn and Volberg--Treil
embedding theorems for the model (star-invariant) subspaces which are special
classes of de Branges--Rovnyak spaces. We also exploit the inequalities for the
derivatives to study stability of Riesz bases of reproducing kernels
$\{k^b_{\lambda_n}\}$ in $\mathcal{H}(b)$ under small perturbations of the
points $\lambda_n$.


title:
Short-range structure of proton conducting perovskite
  BaIn_{x}Zr_{1-x}O_{3-x/2} (x = 0-0.75)

abstract:
  In a systematic study we investigate the effect of dopant level and hydration
on the short-range structure of the proton conducting perovskite-type oxide
BaIn_{x}Zr_{1-x}O_{3-x/2} (x = 0-0.75), using infrared and Raman spectroscopy.
The results show that doping leads to significant local distortions of the
average cubic structure of these materials. By increasing the In concentration
from x = 0 to x = 0.75 new bands appear and grow in intensity in both the IR
and Raman spectra, showing that the local distortions become successively more
and more pronounced. The structural distortions are largely uncorrelated to the
presence of oxygen vacancies, but instead are mainly driven by the size
difference between the In^{3+} and Zr^{4+} ions, which leads to displacements
of the cations and to tilting of the (In/Zr)O_{6} octahedra. Based on our
results, we suggest that there is a threshold between x = 0.10 and x = 0.25
where the local structural distortions propagate throughout the whole
perovskite structure. Comparison of our spectroscopic data with the proton
conductivity reported for the same materials indicates that the presence of
extended structural distortions are favorable for fast proton transport.


title: A translation-invariant renormalizable non-commutative scalar model

abstract:
  In this paper we propose a translation-invariant scalar model on the Moyal
space. We prove that this model does not suffer from the UV/IR mixing and we
establish its renormalizability to all orders in perturbation theory.


title:
Integral representation of the $n$-th derivative in de Branges-Rovnyak
  spaces and the norm convergence of its reproducing kernel

abstract:
  In this paper, we give an integral representation for the boundary values of
derivatives of functions of the de Branges--Rovnyak spaces $\HH(b)$, where $b$
is in the unit ball of $H^\infty(\CC_+)$. In particular, we generalize a result
of Ahern--Clark obtained for functions of the model spaces $K_b$, where $b$ is
an inner function. Using hypergeometric series, we obtain a nontrivial formula
of combinatorics for sums of binomial coefficients. Then we apply this formula
to show the norm convergence of reproducing kernel $k_{\omega,n}^b$ of the
evaluation of $n$-th derivative of elements of $\HH(b)$ at the point $\omega$
as it tends radially to a point of the real axis.


title:
A multiple covariance approach to PLS regression with several predictor
  groups: Structural Equation Exploratory Regression

abstract:
  A variable group Y is assumed to depend upon R thematic variable groups X 1,
>..., X R . We assume that components in Y depend linearly upon components in
the Xr's. In this work, we propose a multiple covariance criterion which
extends that of PLS regression to this multiple predictor groups situation. On
this criterion, we build a PLS-type exploratory method - Structural Equation
Exploratory Regression (SEER) - that allows to simultaneously perform dimension
reduction in groups and investigate the linear model of the components. SEER
uses the multidimensional structure of each group. An application example is
given.


title:
Mod\'elisation factorielle des interactions entre deux ensembles
  d'observations : la m\'ethode PLS-FILM (Partial Least Squares Factor
  Interaction Linear Modelling)

abstract:
  In this work, we consider a data array encoding interactions between two sets
of observations respectively referred to as "subjects" and "objects". Besides,
descriptions of subjects and objects are available through two variable sets.
We propose a geometrically grounded exploratory technique to analyze the
interactions using descriptions of subjects and objects: interactions are
modelled using a hierarchy of subject-factors and object-factors built up from
these descriptions. Our method bridges the gap between those of Chessel (RLQ
analysis) and Martens (L-PLS), although it only has rank 1 components in common
with them.


title:
Tight-binding electronic spectra on graphs with spherical topology. II.
  The effect of spin-orbit interaction

abstract:
  This is the second of two papers devoted to tight-binding electronic spectra
on graphs with the topology of the sphere. We investigate the problem of an
electron subject to a spin-orbit interaction generated by the radial electric
field of a static point charge sitting at the center of the sphere. The
tight-binding Hamiltonian considered is a discretization on polyhedral graphs
of the familiar form ${\bm L}\cdot{\bm S}$ of the spin-orbit Hamiltonian. It
involves SU(2) hopping matrices of the form $\exp({\rm i}\mu{\bm
n}\cdot{\bm\sigma})$ living on the oriented links of the graph. For a given
structure, the dimensionless coupling constant $\mu$ is the only parameter of
the model. An analysis of the energy spectrum is carried out for the five
Platonic solids (tetrahedron, cube, octahedron, dodecahedron and icosahedron)
and the C$_{60}$ fullerene. Except for the latter, the $\mu$-dependence of all
the energy levels is obtained analytically in closed form. Rather unexpectedly,
the spectra are symmetric under the exchange $\mu\leftrightarrow\Theta-\mu$,
where $\Theta$ is the common arc length of the links. For the symmetric point
$\mu=\Theta/2$, the problem can be exactly mapped onto a tight-binding model in
the presence of the magnetic field generated by a Dirac monopole, studied
recently. The dependence of the total energy at half filling on $\mu$ is
investigated in all examples.


title: Models of Comptonization

abstract:
  After a rapid introduction about the models of comptonization, we present
some simulations that underlines the expected capabilities of Simbol-X to
constrain the presence of this process in objects like AGNs or XRB.


title:
Central Limit Theorems for Wavelet Packet Decompositions of Stationary
  Random Processes

abstract:
  This paper provides central limit theorems for the wavelet packet
decomposition of stationary band-limited random processes. The asymptotic
analysis is performed for the sequences of the wavelet packet coefficients
returned at the nodes of any given path of the $M$-band wavelet packet
decomposition tree. It is shown that if the input process is centred and
strictly stationary, these sequences converge in distribution to white Gaussian
processes when the resolution level increases, provided that the decomposition
filters satisfy a suitable property of regularity. For any given path, the
variance of the limit white Gaussian process directly relates to the value of
the input process power spectral density at a specific frequency.


title:
Dynamic polarization effects on the angular distributions of protons
  channeled through carbon nanotubes in dielectric media

abstract:
  The best level of ordering and straightening of carbon nanotube arrays is
often achieved when they are grown in a dielectric matrix, so such structures
present the most suitable candidates for future channeling experiments with
carbon nanotubes. Consequently, we investigate here how the dynamic
polarization of carbon valence electrons in the presence of various surrounding
dielectric media affects the angular distributions of protons channeled through
(11,~9) single-wall carbon nanotubes. Proton speeds between 3 and 10 a.u.,
corresponding to energies of 0.223 and 2.49 MeV, are chosen with the nanotube's
length varied between 0.1 and 1 $\mu$m. We describe the repulsive interaction
between a proton and the nanotube's atoms in a continuum-potential
approximation based on the Doyle-Turner potential, whereas the attractive image
force on a proton is calculated using a two-dimensional hydrodynamic model for
the dynamic response of the nanotube valence electrons, while assigning to the
surrounding medium an appropriate (frequency dependent) dielectric function.
The angular distributions of channeled protons are generated using a computer
simulation method which solves the proton equations of motion in the transverse
plane numerically. Our analysis shows that the presence of a dielectric medium
can strongly affect both the appearance and positions of maxima in the angular
distributions of channeled protons.


title:
D\'eveloppement et analyse multi outils d'un protocole MAC
  d\'eterministe pour un r\'eseau de capteurs sans fil

abstract:
  In this article, we present a multi-tool method for the development and the
analysis of a new medium access method. IEEE 802.15.4 / ZigBee technology has
been used as a basis for this new determinist MAC layer which enables a high
level of QoS. This WPAN can be typically used for wireless sensor networks
which require strong temporal constraints. To validate the proposed protocol,
three complementary and adequate tools are used: Petri Nets for the formal
validation of the algorithm, a dedicated simulator for the temporal aspects,
and some measures on a real prototype based on a couple of ZigBee FREESCALE
components for the hardware characterization of layers #1 and #2.


title: The ziqqurath of exact sequences of n-groupoids

abstract:
  Higher Dimensional Categories are showing relevant implications in several
fields of mathematical research. Nevertheless basic algebraic tools, in order
to further develop the theory, are far from being established. In this thesis
we introduce a notion of exactness for exact sequences of pointed n-groupoids.
Furthermore we test it generalizing a well known result for (fibrations of)
groupoids [R.Brown, 1970]. Namely, given a fibration F of (pointed) groupoids
and its strict kernel it is possible to obtain a 6-term exact sequence of
groups (of loops) and pointed sets (iso classes of objects). The ziqqurath, aka
step-pyramid, comes out from iterating this construction, and it consists in
several sequences of n-groupoids, (n-1)-groupoids and so on up to pointed sets
(0-groupoids), of increasing length.


title: Chern-Simons theory in the SO(5)/U(2) harmonic superspace

abstract:
  We consider the superspace of D=3, N=5 supersymmetry using SO(5)/U(2)
harmonic coordinates. Three analytic N=5 gauge superfields depend on three
vector and six harmonic bosonic coordinates and also on six Grassmann
coordinates. Decomposition of these superfields in Grassmann and harmonic
coordinates yields infinite-dimensional supermultiplets including a
three-dimensional gauge Chern-Simons field and auxiliary bosonic and fermionic
fields carrying SO(5) vector indices. The superfield action of this theory is
invariant with respect to D=3, N=6 conformal supersymmetry realized on N=5
superfields.


title:
On Approximating Frequency Moments of Data Streams with Skewed
  Projections

abstract:
  We propose skewed stable random projections for approximating the pth
frequency moments of dynamic data streams (0<p<=2), which has been frequently
studied in theoretical computer science and database communities. Our method
significantly (or even infinitely when p->1) improves previous methods based on
(symmetric) stable random projections.
  Our proposed method is applicable to data streams that are (a) insertion only
(the cash-register model); or (b) always non-negative (the strict Turnstile
model), or (c) eventually non-negative at check points. This is only a minor
restriction for practical applications.
  Our method works particularly well when p = 1+/- \Delta and \Delta is small,
which is a practically important scenario. For example, \Delta may be the decay
rate or interest rate, which are usually small. Of course, when \Delta = 0, one
can compute the 1th frequent moment (i.e., the sum) essentially error-free
using a simple couter. Our method may be viewed as a ``genearlized counter'' in
that it can count the total value in the future, taking in account of the
effect of decaying or interest accruement.
  In a summary, our contributions are two-fold. (A) This is the first propsal
of skewed stable random projections. (B) Based on first principle, we develop
various statistical estimators for skewed stable distributions, including their
variances and error (tail) probability bounds, and consequently the sample
complexity bounds.


title:
Quasar spectral energy distribution in EUV restored from associated
  absorbers: indications to the HeII opacity of the quasar accretion disk wind

abstract:
  (abridged) Aims. To reconstruct the spectral shape of the quasar ionizing
radiation in the extreme-UV range (1Ryd <= E < 10Ryd) from the analysis of
narrow absorption lines (NAL) of the associated systems. Methods. Computational
technique for inverse spectroscopic problems - Monte Carlo Inversion augmented
by procedure of the spectral shape recovering and modified to account for the
incomplete coverage of the light source. Results. The ionizing spectra
responsible for the ionization structure of the NAL systems require an
intensity depression at E > 4Ryd which is attributed to the HeII Lyman
continuum opacity (tau^HeII_c ~ 1). A most likely source of this opacity is a
quasar accretion disk wind. The corresponding column density of HI in the wind
is estimated as a few times 10^16 cm^-2. This amount of neutral hydrogen should
cause a weak continuum depression at lamb <= 912A (rest-frame), and a broad and
shallow absorption in HI Ly-alpha. If metallicity of the wind is high enough,
other resonance lines of OVI, NeVI-NeVIII, etc. are expected. In the analyzed
QSO spectra we do observe broad (stretching over 1000s km/s) and shallow (tau
<< 1) absorption troughs of HI Ly-alpha and OVI 1031,1037A...


title: SAR Altimetry Applications over Water

abstract:
  The application of Synthetic Aperture Radar (SAR) techniques to classical
radar altimetry offers the potential for greatly improved Earth surface
mapping. This paper provides an overview of the progress of SAMOSA, Development
of SAR Altimetry Studies and Applications over Ocean, Coastal zones and Inland
waters, an on-going ESA-funded project. The main objective of SAMOSA is to
better quantify the improvement of SAR altimetry over conventional altimetry on
water surfaces. More specifically, one of the tasks focuses on the reduction of
SAR mode data to pulse-limited altimeter data, and a theoretical modelling to
characterize the expected gain between high Pulse Repetition Frequency (PRF)
reduced SAR mode data and low PRF classical Low-Resolution Mode (LRM) data. To
this end, theoretical modelling using the Cramer-Rao bound (CRB) will be used
and the results will be compared to previous theoretical estimates [7], using
an analysis akin to that in [8].


title:
Submanifolds of codimension two attaining equality in an extrinsic
  inequality

abstract:
  We provide a parametric construction in terms of minimal surfaces of the
Euclidean submanifolds of codimension two and arbitrary dimension that attain
equality in an inequality due to De Smet, Dillen, Verstraelen and Vrancken. The
latter involves the scalar curvature, the norm of the normal curvature tensor
and the length of the mean curvature vector.


title: Relative Pro-$\ell$ Completions of Mapping Class Groups

abstract:
  Fix a prime number ell. In this paper we develop the theory of relative
pro-ell completion of discrete and profinite groups -- a natural generalization
of the classical notion of pro-ell completion -- and show that the pro-ell
completion of the Torelli group does not inject into the relative pro-ell
completion of the corresponding mapping class group when the genus is at least
3. As an application, we prove that when g > 2, the action of the pro-ell
completion of the Torelli group T_{g,1} on the pro-ell fundamental group of a
pointed genus g surface is not faithful.
  The choice of a first-order deformation of a maximally degenerate stable
curve of genus g determines an action of the absolute Galois group G_Q on the
relative pro-ell completion of the corresponding mapping class group. We prove
that for all g all such representations are unramified at all primes \neq ell
when the first order deformation is suitably chosen. This proof was
communicated to us by Mochizuki and Tamagawa.


title:
Fluctuation-Dissipation Relations and statistical temperatures in a
  turbulent von K\'arm\'an flow

abstract:
  We experimentally characterize the fluctuations of the non-homogeneous
non-isotropic turbulence in an axisymmetric von K\'arm\'an flow. We show that
these fluctuations satisfy relations analogous to classical
Fluctuation-Dissipation Relations (FDRs) in statistical mechanics. We use these
relations to measure statistical temperatures of turbulence. The values of
these temperatures are found to be dependent on the considered observable as
already evidenced in other far from equilibrium systems.


title:
Turbo Interleaving inside the cdma2000 and W-CDMA Mobile Communication
  Systems: A Tutorial

abstract:
  In this paper a discussion of the detailed operation of the interleavers used
by the turbo codes defined on the telecommunications standards cdma2000 (3GPP2
C.S0024-B V2.0) and W-CDMA (3GPP TS 25.212 V7.4.0) is presented. Differences in
the approach used by each turbo interleaver as well as dispersion analysis and
frequency analysis are also discussed. Two examples are presented to illustrate
the complete interleaving process defined by each standard. These two
interleaving approaches are also representative for other communications
standards.


title: On the weak K\"ahler-Ricci flow

abstract:
  In this note, we define and study K\"ahler-Ricci flow with initial data not
being smooth with some natural applications.


title: On the relative Giroux correspondence

abstract:
  Recently, Honda, Kazez and Matic described an adapted partial open book of a
compact contact 3-manifold with convex boundary by generalizing the work of
Giroux in the closed case. They also implicitly established a one-to-one
correspondence between isomorphism classes of partial open book decompositions
modulo positive stabilization and isomorphism classes of compact contact
3-manifolds with convex boundary. In this expository article we explicate the
relative version of Giroux correspondence.


title:
Switchable ErSc2N rotor within a C80 fullerene cage: An EPR and
  photoluminescence excitation study

abstract:
  Systems exhibiting both spin and orbital degrees of freedom, of which Er3+ is
one, can offer mechanisms for manipulating and measuring spin states via
optical excitations. Motivated by the possibility of observing
photoluminescence and electron paramagnetic resonance from the same species
located within a fullerene molecule, we initiated an EPR study of Er3+ in
ErSc2N@C80. Two orientations of the ErSc2N rotor within the C80 fullerene are
observed in EPR, consistent with earlier studies using photoluminescence
excitation (PLE) spectroscopy. For some crystal field orientations, electron
spin relaxation is driven by an Orbach process via the first excited electronic
state of the 4I_15/2 multiplet. We observe a change in the relative populations
of the two ErSc2N configurations upon the application of 532 nm illuminations,
and are thus able to switch the majority cage symmetry. This
photoisomerisation, observable by both EPR and PLE, is metastable, lasting many
hours at 20 K.


title: The Kauffman skein algebra of a surface at $\sqrt{-1}$

abstract:
  We study the structure of the Kauffman algebra of a surface with parameter
equal to sqrt(-1). We obtain an interpretation of this algebra as an algebra of
parallel transport operators acting on sections of a line bundle over the
moduli space of flat connections in a trivial SU(2)-bundle over the surface. We
analyse the asymptotics of traces of curve-operators in TQFT in non standard
regimes where the root of unity parametrizing the TQFT accumulates to a root of
unity. We interpret the case of sqrt(-1) in terms of parallel transport
operators.


title: Jet rates in electron-positron annihilation at O(\alpha_s^3) in QCD

abstract:
  We compute production rates for two, three, four and five jets in
electron-positron annihilation at the third order in the QCD coupling constant.
At this order, three-jet production is described to next-to-next-to-leading
order (NNLO) in perturbation theory while the two-jet rate is obtained at
next-to-next-to-next-to-leading order (N$^3$LO). Our results yield an improved
perturbative description of the dependence of jet multiplicity on the jet
resolution parameter, $\ycut$, particularly at small values of $\ycut$.


title: Relative Weight Filtrations on Completions of Mapping Class Groups

abstract:
  This paper gives an exposition of relative weight filtrations on completions
of mapping class groups associated to a stable degeneration of marked genus g
curves. These relative weight filtrations have been constructed using Galois
theory (with Matsumoto) and Hodge theory (with Pearlstein and Terasoma). It is
shown that the level 0 part of the relative weight filtration is an analogue of
a parabolic subalgebra of a Kac-Moody Lie algebra. It is shown that all such
subalgebras correspond to equivalence classes of pants decompositions of the
surface -- two being equivalent if and only if they determine the same
handlebody that the reference surface bounds. One application is to show that
handlebody subgroups of mapping class groups contain elements arbitrarily far
down the lower central series of Torelli groups. (This result was also obtained
independently by Jamie Jorgensen.)


title:
A downward revision to the distance of the 1806-20 cluster and
  associated magnetar from Gemini near-Infrared spectroscopy

abstract:
  We present H- and K-band spectroscopy of OB and Wolf-Rayet (WR) members of
the Milky Way cluster 1806-20 (G10.0-0.3), to obtain a revised cluster distance
of relevance to the 2004 giant flare from the SGR 1806-20 magnetar. From GNIRS
spectroscopy obtained with Gemini South, four candidate OB stars are confirmed
as late O/early B supergiants, while we support previous mid WN and late WC
classifications for two WR stars. Based upon an absolute Ks-band magnitude
calibration for B supergiants and WR stars, and near-IR photometry from NIRI at
Gemini North plus archival VLT/ISAAC datasets, we obtain a cluster distance
modulus of 14.7+/-0.35 mag. The known stellar content of the 1806-20 cluster
suggests an age of 3-5 Myr, from which theoretical isochrone fits infer a
distance modulus of 14.7+/-0.7 mag. Together, our results favour a distance
modulus of 14.7+/-0.4 mag (8.7^+1.8_-1.5 kpc) to the 1806-20 cluster, which is
significantly lower than the nominal 15 kpc distance to the magnetar. For our
preferred distance, the peak luminosity of the December 2004 giant flare is
reduced by a factor of three to 7 X 10^46 erg/s, such that the contamination of
BATSE short gamma ray bursts (GRB's) from giant flares of extragalactic
magnetars is reduced to a few percent. We infer a magnetar progenitor mass of
~48^+20_-8 Msun, in close agreement with that obtained recently for the
magnetar in Westerlund 1.


title:
Optical and infrared emission from discs, jets and nebulae associated
  with X-ray binaries

abstract:
  X-ray binaries are binary star systems in which a compact object (a neutron
star or a black hole) and a relatively normal star orbit a common centre of
mass. Since the discovery of X-ray binaries with the first X-ray telescopes in
the 1960s, astronomers have tried to understand how these bizarre objects
behave, and why. Some change in X-ray luminosity by 10^8 orders of magnitude on
timescales of days to months due to an increased transfer of mass from the star
towards the compact object. Many X-ray binaries are detected at all observable
frequencies, from radio to gamma-rays. It has been found that many different
sources of emission, which peak at different frequencies, are present in X-ray
binary spectra and together they produce the observed broadband spectrum.
However, disentangling these components has proved challenging. Much of the
work in this thesis concerns disentangling the components that occupy the
optical and near-infrared (NIR) region of the spectrum of X-ray binaries;
possibly the region in which the relative contributions of the different
components are least certain. In particular one component, the synchrotron
emission from jets of outflowing matter, is found in this work to contribute
ubiquitously to the optical and NIR light of X-ray binaries with relatively
faint stars. These results confirm that the jets are powerful and in some of
this work, observations of the jets interacting with the surrounding matter are
used to infer their power.


title:
Asymptotic normality of the mixture density estimator in a
  disaggregation scheme

abstract:
  The paper concerns the asymptotic distribution of the mixture density
estimator, proposed by Oppenheim et al 2006, in the aggregation/disaggregation
problem of random parameter AR(1) process. We prove that, under mild conditions
on the (semiparametric) form of the mixture density, the estimator is
asymptotically normal. The proof is based on the limit theory for the quadratic
form in linear random variables developed by Bhansali et al 2007. The moving
average representation of the aggregated process is investigated. A small
simulation study illustrates the result.


title: VHE emission from M82

abstract:
  Spurred by the improved measurement sensitivity in the very-high-energy (VHE:
>100 GeV) gamma-ray band, we assess the feasibility of detection of the nearby
starburst galaxy M82. VHE emission is expected to be predominantly from the
decay of neutral pions which are produced in energetic proton interactions with
ambient protons. An estimate of VHE emission from this process is obtained by
an approximate, semi-quantitative calculation, and also by a detailed numerical
treatment based on a convection-diffusion model for energetic electron and
proton propagation and energy losses. All relevant hadronic and leptonic
processes are considered, gauged by the measured synchrotron radio emission
from the inner disk region. We estimate an integrated flux f(>100 GeV) 2E-12
1/(cm^2 s), possibly detectable by the current northern-hemisphere imaging air
Cherenkov telescopes, MAGIC and VERITAS, and a good candidate for detection
with the upcoming MAGIC II telescope. We also estimate f(>100 MeV) E-8 1/(cm^2
s), a level of emission that can be detected by GLAST/LAT based on the
projected sensitivity for a one-year observation.


title: The Coherent Radio Emission from the RS CVn Binary HR 1099

abstract:
  We used the Australia Telescope in March-April 2005 to observe the RS CVn
binary HR 1099 at 1.384 and 2.368 GHz at two epochs, each of 9 h in duration
and 11 days apart. During two episodes of coherent emission, we employed a
recently installed facility to sample the data at 78 ms intervals to measure
the fine temporal and spectral structure of HR 1099. Our main observational
results include: ~100% left hand circularly polarised emission was seen at both
1.384 and 2.368 GHz during both epochs; in the first event the emission feature
drifted across the spectrum; three 22 min integrations made at 78 ms time
resolution showed that the modulation index of the Stokes V parameter increased
monotonically as the integration time was decreased and was still increasing at
our resolution limit; we believe that the highly polarised emission is due to
electron-cyclotron maser emission (ECME) operating in the corona of one of the
binary components. We discuss two kinds of maser sources that may be
responsible for driving the observed events. We suggest that the ECME source
may be an aurora-like phenomenon due to the transfer of plasma from the K2
subgiant to the G5 dwarf in a strong stellar wind.


title: Independence and concurrent separation logic

abstract:
  A compositional Petri net-based semantics is given to a simple language
allowing pointer manipulation and parallelism. The model is then applied to
give a notion of validity to the judgements made by concurrent separation logic
that emphasizes the process-environment duality inherent in such rely-guarantee
reasoning. Soundness of the rules of concurrent separation logic with respect
to this definition of validity is shown. The independence information retained
by the Petri net model is then exploited to characterize the independence of
parallel processes enforced by the logic. This is shown to permit a refinement
operation capable of changing the granularity of atomic actions.


title: The Centurion 18 telescope of the Wise Observatory

abstract:
  We describe the second telescope of the Wise Observatory, a 0.46-m Centurion
18 (C18) installed in 2005, which enhances significantly the observing
possibilities. The telescope operates from a small dome and is equipped with a
large-format CCD camera. In the last two years this telescope was intensively
used in a variety of monitoring projects.
  The operation of the C18 is now automatic, requiring only start-up at the
beginning of a night and close-down at dawn. The observations are mostly
performed remotely from the Tel Aviv campus or even from the observer's home.
The entire facility was erected for a component cost of about 70k$ and a labor
investment of a total of one man-year.
  We describe three types of projects undertaken with this new facility: the
measurement of asteroid light variability with the purpose of determining
physical parameters and binarity, the following-up of transiting extrasolar
planets, and the study of AGN variability. The successful implementation of the
C18 demonstrates the viability of small telescopes in an age of huge
light-collectors, provided the operation of such facilities is very efficient.


title:
Effect of magnetic fields on the spin evolution of non-polarized 87Rb
  Bose-Einstein condensates

abstract:
  The spin mixing dynamics of spin-1 Bose-Einstein condensates with zero
magnetization and under an external magnetic field is investigated. The
time-dependent solutions are obtained via a diagonalization of the Hamiltonian,
which has a simple form under the single mode approximation. The features of
evolution are compared in detail with those with the field removed so as to
emphasize the effect of the field, which can induce strong oscillation in
population of atoms in spin component 0 . A new mode of oscillation
characterized by a high frequency and a low frequency, is found when the field
is sufficiently strong.


title: Doubly-Generalized LDPC Codes: Stability Bound over the BEC

abstract:
  The iterative decoding threshold of low-density parity-check (LDPC) codes
over the binary erasure channel (BEC) fulfills an upper bound depending only on
the variable and check nodes with minimum distance 2. This bound is a
consequence of the stability condition, and is here referred to as stability
bound. In this paper, a stability bound over the BEC is developed for
doubly-generalized LDPC codes, where the variable and the check nodes can be
generic linear block codes, assuming maximum a posteriori erasure correction at
each node. It is proved that in this generalized context as well the bound
depends only on the variable and check component codes with minimum distance 2.
A condition is also developed, namely the derivative matching condition, under
which the bound is achieved with equality.


title: Anisotropic colloids through non-trivial buckling

abstract:
  We present a study on buckling of colloidal particles, including
experimental, theoretical and numerical developments. Oil-filled thin shells
prepared by emulsion templating show buckling in mixtures of water and ethanol,
due to dissolution of the core in the external medium. This leads to
conformations with a single depression, either axisymmetric or polygonal
depending on the geometrical features of the shells. These conformations could
be theoretically and/or numerically reproduced in a model of homogeneous
spherical thin shells with bending and stretching elasticity, submitted to an
isotropic external pressure.


title: Chandra unveils a binary Active Galactic Nucleus in Mrk463

abstract:
  We analyse Chandra, XMM-Newton and HST data of the double-nucleus
Ultraluminous Infrared Galaxy (ULIRG), Mrk463. The Chandra detection of two
luminous ($\mathrm{L}_\mathrm{2-10 keV}=1.5\times10^{43}$ and
$3.8\times10^{42}$ erg cm$^{-2}$ s$^{-1}$), unresolved nuclei in Mrk~463
indicates that this galaxy hosts a binary AGN, with a projected separation of
$\simeq3.8$ kpc ($3.83\pm0.01$ arcsec). While the East nucleus was already
known to be a Seyfert 2 (and this is further confirmed by our Chandra detection
of a neutral iron line), this is the first unambiguous evidence in favour of
the AGN nature of the West nucleus. Mrk463 is therefore the clearest case so
far for a binary AGN, after NGC6240.


title: Characterizations of Lojasiewicz inequalities and applications

abstract:
  The classical Lojasiewicz inequality and its extensions for partial
differential equation problems (Simon) and to o-minimal structures (Kurdyka)
have a considerable impact on the analysis of gradient-like methods and related
problems: minimization methods, complexity theory, asymptotic analysis of
dissipative partial differential equations, tame geometry. This paper provides
alternative characterizations of this type of inequalities for nonsmooth lower
semicontinuous functions defined on a metric or a real Hilbert space. In a
metric context, we show that a generalized form of the Lojasiewicz inequality
(hereby called the Kurdyka-Lojasiewicz inequality) relates to metric regularity
and to the Lipschitz continuity of the sublevel mapping, yielding applications
to discrete methods (strong convergence of the proximal algorithm). In a
Hilbert setting we further establish that asymptotic properties of the semiflow
generated by $-\partial f$ are strongly linked to this inequality. This is done
by introducing the notion of a piecewise subgradient curve: such curves have
uniformly bounded lengths if and only if the Kurdyka-Lojasiewicz inequality is
satisfied. Further characterizations in terms of talweg lines -a concept linked
to the location of the less steepest points at the level sets of $f$- and
integrability conditions are given. In the convex case these results are
significantly reinforced, allowing in particular to establish the asymptotic
equivalence of discrete gradient methods and continuous gradient curves. On the
other hand, a counterexample of a convex C^2 function in in the plane is
constructed to illustrate the fact that, contrary to our intuition, and unless
a specific growth condition is satisfied, convex functions may fail to fulfill
the Kurdyka-Lojasiewicz inequality.


title: Joinings of W*-dynamical systems

abstract:
  We study the notion of joinings of W*-dynamical systems, building on ideas
from measure theoretic ergodic theory. In particular we prove sufficient and
necessary conditions for ergodicity in terms of joinings, and also briefly look
at conditional expectation operators associated with joinings.


title: The Invisible Quantum Barrier

abstract:
  We construct the invisible quantum barrier which represents the phenomenon of
quantum reflection using the available data. We use the Abel equation to invert
the data. The resulting invisible quantum barrier is double-valued in both
axes. We study this invisible barrier in the case of atom and Bose-Einstein
Condensate reflection from a solid silicon surface. A time-dependent,
one-spatial dimension Gross-Pitaevskii equation is solved for the BEC case. We
found that the BEC behaves very similarly to the single atom except for size
effects, which manifest themselves in a maximum in the reflectivity at small
distances from the wall. The effect of the atom-atom interaction on the BEC
reflection and correspondingly on the invisible barrier is found to be
appreciable at low velocities and comparable to the finite size effect. The
trapping of ultracold atoms or BEC between two walls is discussed.


title:
Large Magnetoresistance in a Manganite Spin-Tunnel-Junction Using LaMnO3
  as Insulating Barrier

abstract:
  A spin-tunnel-junction based on manganites, with La$_{1-x}$Sr$_x$MnO$_3$
(LSMO) as ferromagnetic metallic electrodes and the undoped parent compound
LaMnO$_3$ (LMO) as insulating barrier, is here theoretically discussed using
double exchange model Hamiltonians and numerical techniques. For an even number
of LMO layers, the ground state is shown to have anti-parallel LSMO magnetic
moments. This highly resistive, but fragile, state is easily destabilized by
small magnetic fields, which orient the LSMO moments in the direction of the
field. The magnetoresistance associated with this transition is very large,
according to Monte Carlo and Density Matrix Renormalization Group studies. The
influence of temperature, the case of an odd number of LMO layers, and the
differences between LMO and SrTiO$_3$ as barriers are also addressed. General
trends are discussed.


title: LHC signatures for Z` models with continuously distributed mass

abstract:
  We discuss phenomenological consequences of renormalizable Z` models with
continuously distributed mass. We point out that one of possible LHC signatures
for such nodel is the existence of broad resonance in Drell-Yan reaction $pp
\to Z^{`} \to l^+l^-$.


title: Surface deformation caused by the Abrikosov vortex lattice

abstract:
  In superconductors penetrated by Abrikosov vortices the magnetic pressure and
the inhomogeneous condensate density induce a deformation of the ionic lattice.
We calculate how this deformation corrugates the surface of a semi-infinite
sample. The effect of the surface dipole is included.


title: Distributed Double Spending Prevention

abstract:
  We study the problem of preventing double spending in electronic payment
schemes in a distributed fashion. This problem occurs, for instance, when the
spending of electronic coins needs to be controlled by a large collection of
nodes (eg. in a peer-to-peer (P2P) system) instead of one central bank.
Contrary to the commonly held belief that this is fundamentally impossible, we
propose several solutions that do achieve a reasonable level of double spending
prevention, and analyse their efficiency under varying assumptions.


title:
The inherent fluctuations of the pulsed atom laser in F=2 manifold of
  87Rb atoms

abstract:
  We have observed the intensity fluctuations of the F=2 87Rb atom laser at low
output coupling rate. Theoretically, we find that the atom loss of the
condensate due to the output of atom laser leads to fluctuations of the laser
pulses, which is inherent in all state changing out-coupling such as rf and
Raman. Another reason leading to large fluctuations is the interference of
output pulses.


title: The Ephemeral Pairing Problem

abstract:
  In wireless ad-hoc broadcast networks the pairing problem consists of
establishing a (long-term) connection between two specific physical nodes in
the network that do not yet know each other. We focus on the ephemeral version
of this problem. Ephemeral pairings occur, for example, when electronic
business cards are exchanged between two people that meet, or when one pays at
a check-out using a wireless wallet.
  This problem can, in more abstract terms, be phrased as an ephemeral key
exchange problem: given a low bandwidth authentic (or private) communication
channel between two nodes, and a high bandwidth broadcast channel, can we
establish a high-entropy shared secret session key between the two nodes
without relying on any a priori shared secret information.
  Apart from introducing this new problem, we present several ephemeral key
exchange protocols, both for the case of authentic channels as well as for the
case of private channels.


title: Bit-Optimal Lempel-Ziv compression

abstract:
  One of the most famous and investigated lossless data-compression scheme is
the one introduced by Lempel and Ziv about 40 years ago. This compression
scheme is known as "dictionary-based compression" and consists of squeezing an
input string by replacing some of its substrings with (shorter) codewords which
are actually pointers to a dictionary of phrases built as the string is
processed. Surprisingly enough, although many fundamental results are nowadays
known about upper bounds on the speed and effectiveness of this compression
process and references therein), ``we are not aware of any parsing scheme that
achieves optimality when the LZ77-dictionary is in use under any constraint on
the codewords other than being of equal length'' [N. Rajpoot and C. Sahinalp.
Handbook of Lossless Data Compression, chapter Dictionary-based data
compression. Academic Press, 2002. pag. 159]. Here optimality means to achieve
the minimum number of bits in compressing each individual input string, without
any assumption on its generating source. In this paper we provide the first
LZ-based compressor which computes the bit-optimal parsing of any input string
in efficient time and optimal space, for a general class of variable-length
codeword encodings which encompasses most of the ones typically used in data
compression and in the design of search engines and compressed indexes.


title: Sub-Doppler laser cooling and magnetic trapping of erbium

abstract:
  We investigate cooling mechanisms in magneto-optically and magnetically
trapped erbium. We find efficient sub-Doppler cooling in our trap, which can
persist even in large magnetic fields due to the near degeneracy of two Lande g
factors. Furthermore, a continuously loaded magnetic trap is demonstrated where
we observe temperatures below 25 microkelvin. These favorable cooling and
trapping properties suggest a number of scientific possibilities for rare-earth
atomic physics, including narrow linewidth laser cooling and spectroscopy,
unique collision studies, and degenerate bosonic and fermionic gases with
long-range magnetic dipole coupling.


title: Data-driven calibration of penalties for least-squares regression

abstract:
  Penalization procedures often suffer from their dependence on multiplying
factors, whose optimal values are either unknown or hard to estimate from the
data. We propose a completely data-driven calibration algorithm for this
parameter in the least-squares regression framework, without assuming a
particular shape for the penalty. Our algorithm relies on the concept of
minimal penalty, recently introduced by Birge and Massart (2007) in the context
of penalized least squares for Gaussian homoscedastic regression. On the
positive side, the minimal penalty can be evaluated from the data themselves,
leading to a data-driven estimation of an optimal penalty which can be used in
practice; on the negative side, their approach heavily relies on the
homoscedastic Gaussian nature of their stochastic framework. The purpose of
this paper is twofold: stating a more general heuristics for designing a
data-driven penalty (the slope heuristics) and proving that it works for
penalized least-squares regression with a random design, even for
heteroscedastic non-Gaussian data. For technical reasons, some exact
mathematical results will be proved only for regressogram bin-width selection.
This is at least a first step towards further results, since the approach and
the method that we use are indeed general.


title: Nuclear Energy Density Functionals Constrained by Low-Energy QCD

abstract:
  A microscopic framework of nuclear energy density functionals is reviewed,
which establishes a direct relation between low-energy QCD and nuclear
structure, synthesizing effective field theory methods and principles of
density functional theory. Guided by two closely related features of QCD in the
low-energy limit: a) in-medium changes of vacuum condensates, and b)
spontaneous breaking of chiral symmetry; a relativistic energy density
functional is developed and applied in studies of ground-state properties of
spherical and deformed nuclei.


title:
The Suppression and Recovery of the Ferroelectric Phase in Multiferroic
  $MnWO_4$

abstract:
  We report the discovery of a complete suppression of ferroelectricity in
$MnWO_4$ by 10 % iron substitution and its restoration in external magnetic
fields. The spontaneous polarization in $Mn_{0.9}Fe_{0.1}WO_4$ arises below 12
K in external fields above 4 T. The magnetic/ferroelectric phase diagram is
constructed from the anomalies of the dielectric constant, polarization,
magnetization, and heat capacity. The observations are qualitatively described
by a mean field model with competing interactions and strong anisotropy. We
propose that the magnetic field induces a non-collinear inversion symmetry
breaking magnetic structure in $Mn_{0.9}Fe_{0.1}WO_4$.


title: Wrapped branes as qubits

abstract:
  Recent work has established a correspondence between the tripartite
entanglement measure of three qubits and the macroscopic entropy of the
four-dimensional 8-charge STU black hole of supergravity. Here we consider the
configurations of intersecting D3-branes, whose wrapping around the six compact
dimensions T^6 provides the microscopic string-theoretic interpretation of the
charges, and associate the three-qubit basis vectors |ABC>, (A,B,C=0 or 1) with
the corresponding 8 wrapping cycles. In particular, we relate a well-known fact
of quantum information theory, that the most general real three-qubit state can
be parameterized by four real numbers and an angle, to a well-known fact of
string theory, that the most general STU black hole can be described by four
D3-branes intersecting at an angle.


title: Isomorphism classes of certain Artinian Gorenstein algebras

abstract:
  In this paper we classify, up to analytic isomorphism, the family of almost
stretched Artinian complete intersection A=R/I with a given Hilbert function,
in the case R is a power series ring with an arbitrary number of variables.


title: Two-dimensional Brownian vortices

abstract:
  We introduce a stochastic model of two-dimensional Brownian vortices
associated with the canonical ensemble. The point vortices evolve through their
usual mutual advection but they experience in addition a random velocity and a
systematic drift generated by the system as a whole. The statistical
equilibrium state of this stochastic model is the Gibbs canonical distribution.
We consider a single species system and a system made of two types of vortices
with positive and negative circulations. At positive temperatures, like-sign
vortices repel each other (plasma case) and at negative temperatures, like-sign
vortices attract each other (gravity case). We derive the stochastic equation
satisfied by the exact vorticity field and the Fokker-Planck equation satisfied
by the N-body distribution function. We present the BBGKY-like hierarchy of
equations satisfied by the reduced distribution functions and close the
hierarchy by considering an expansion of the solutions in powers of 1/N, where
N is the number of vortices, in a proper thermodynamic limit. For spatially
inhomogeneous systems, we derive the kinetic equations satisfied by the smooth
vorticity field in a mean field approximation valid for $N\to +\infty$. For
spatially homogeneous systems, we study the two-body correlation function, in a
Debye-H\"uckel approximation valid at the order O(1/N). The results of this
paper can also apply to other systems of random walkers with long-range
interactions such as self-gravitating Brownian particles and bacterial
populations experiencing chemotaxis. Furthermore, for positive temperatures,
our study provides a kinetic derivation, from microscopic stochastic processes,
of the Debye-H\"uckel model of electrolytes.


title: Group formation with network constraints

abstract:
  Group formation is important in many economic contexts. The current
literature on group formation assumes that individuals may join any existing
group. In this paper, I consider the implications of social, geographic, and
informational constraints to group membership decisions. I embed the players in
a network of relationships, which constrains their choice of groups--they may
only join a group if that group contains a member that they are connected to on
the network. I then examine how this network constraint affects the equilibrium
group structure. I show that even with complete information, unconstrained
individuals form groups that are inefficiently large. When individuals are
constrained, the resulting group structures are much closer to the socially
optimal group structure, because the constraint limits the ability of the
individual to free ride on the efforts of other group members. The efficiency
of the outcome is related to the structure of the network constraint--outcomes
are more efficient when networks are sparse and have few random connections.


title:
Single mode heat rectifier: Controlling energy flow between electronic
  conductors

abstract:
  We study heat transfer between conductors, mediated by the excitation of a
monomodal harmonic oscillator. Using a simple model, we show that the onset of
rectification in the system is directly related to the nonlinearity of the
electron gas dispersion relation. When the metals have strictly linear
dispersion relation a Landauer type expression for the thermal current holds,
symmetric with respect to the temperature difference. Rectification becomes
prominent when deviations from linear dispersion exist, and the fermionic model
cannot be mapped into a harmonic- bosonized- representation. The effects
described here are relevant for understanding radiative heat transfer and
vibrational energy flow in electrically insulating molecular junctions.


title: The Broadband Infrared Emission Spectrum of the Exoplanet HD 189733b

abstract:
  We present Spitzer Space Telescope time series photometry of the exoplanet
system HD 189733 spanning two times of secondary eclipse, when the planet
passes out of view behind the parent star. We estimate the relative eclipse
depth in 5 distinct bands and find the planet-to-star flux ratio to be 0.256
+/- 0.014% (3.6 microns), 0.214 +/- 0.020% (4.5 microns), 0.310 +/- 0.034% (5.8
microns), 0.391 +/- 0.022% (8.0 microns), and 0.598 +/- 0.038% (24 microns).
For consistency, we re-analyze a previously published time series to deduce a
contrast ratio in an additional band, 0.519 +/- 0.020% (16 microns). Our data
are strongly inconsistent with a Planck spectrum, and we clearly detect
emission near 4 microns as predicted by published theoretical models in which
this feature arises from a corresponding opacity window. Unlike recent results
for the exoplanet HD 209458b, we find that the emergent spectrum from HD
189733b is best matched by models that do not include an atmospheric
temperature inversion. Taken together, these two studies provide initial
observational support for the idea that hot Jupiter atmospheres diverge into
two classes, in which a thermal inversion layer is present for the more
strongly irradiated objects.


title:
On the Finite Energy Weak Solutions to a System in Quantum Fluid
  Dynamics

abstract:
  In this paper we consider the global existence of weak solutions to a class
of Quantum Hydrodynamics (QHD) systems with initial data, arbitrarily large in
the energy norm. These type of models, initially proposed by Madelung, have
been extensively used in Physics to investigate Supefluidity and
Superconductivity phenomena and more recently in the modeling of semiconductor
devices . Our approach is based on various tools, namely the wave functions
polar decomposition, the construction of approximate solution via a fractional
steps method, which iterates a Schr\"odinger Madelung picture with a suitable
wave function updating mechanism. Therefore several \emph{a priori} bounds of
energy, dispersive and local smoothing type allow us to prove the compactness
of the approximating sequences. No uniqueness result is provided.


title: Collective behavior of "electronic fireflies"

abstract:
  A simple system composed of electronic oscillators capable of emitting and
detecting light-pulses is studied. The oscillators are biologically inspired,
their behavior is designed for keeping a desired light intensity, W, in the
system. From another perspective, the system behaves like modified integrate
and fire type neurons that are pulse-coupled with inhibitory type interactions:
the firing of one oscillator delays the firing of all the others. Experimental
and computational studies reveal that although no driving force favoring
synchronization is considered, for a given interval of W phase-locking appears.
This weak synchronization is sometimes accompanied by complex dynamical
patterns in the flashing sequence of the oscillators.


title:
Some First Steps Towards a Radiation GRMHD Code: Radiative Effects on
  Accretion Rate onto a Kerr Black Hole

abstract:
  The role of radiation in general relativistic magnetohydrodynamic (GRMHD)
accretion simulations is discussed through axisymmetric simulations of the
evolution of an initial torus seeded with a weak magnetic field. The paper
compares and contrasts the rate of accretion onto a Kerr black hole and mass
flux out out of the initial torus at large radii in the GRMHD code of De
Villiers and Hawley and a newly developed radiative GRMHD code. This rGRMHD
code currently operates in the diffusion approximation, restricting the study
of radiative effects to the bound portion of the accretion disk/jet system.
However, these preliminary findings suggest that radiative effects do play a
potentially significant role in regulating the accretion flow.


title:
The Star Formation Histories of galaxies: A tour through the
  STARLIGHT-SDSS database

abstract:
  Retrieving the Star Formation History (SFH) of a galaxy out of its integrated
spectrum is the central goal of stellar population synthesis. Recent advances
in evolutionary synthesis models have given new breath to this old field of
research. Modern spectral synthesis techniques incorporating these advances now
allow the fitting of galaxy spectra on an angstrom-by-angstrom basis. These
detailed fits are useful for a number of studies, like emission line, stellar
kinematics, and specially galaxy evolution. Applications of this semi-empirical
approach to mega data sets are teaching us a lot about the lives of galaxies.
The STARLIGHT spectral synthesis code is one of the tools which allows one to
harness this favorable combination of plentifulness of data and models. To
illustrate this, we show how SFHs vary across classical emission line
diagnostic diagrams. Systematic trends are present along both the star-forming
and active-galaxy sequences. We also briefly describe experiments with new
versions of evolutionary synthesis models. Last but not least, we announce the
public availability of both STARLIGHT and a database of detailed spectral fits
and related products for over half a million galaxies from the SDSS. This
facility allows more physically inspired explorations of the parameter space
than is possible in terms of raw observed properties, offering new ways to
navigate through the realm of galaxies.


title: On multiwell Liouville theorems in higher dimension

abstract:
  We consider certain subsets of the space of $n\times n$ matrices of the form
$K = \cup_{i=1}^m SO(n)A_i$, and we prove that for $p>1, q \geq 1$ and for
connected $\Omega'\subset\subset\Omega\subset \R^n$, there exists positive
constant $a<1$ depending on $n,p,q, \Omega, \Omega'$ such that for $ \veps=\|
{dist}(Du, K)\|_{L^p(\Omega)}^p$ we have $\inf_{R\in
K}\|Du-R\|^p_{L^p(\Omega')}\leq M\veps^{1/p}$ provided $u$ satisfies the
inequality $\| D^2 u\|_{L^q(\Omega)}^q\leq a\veps^{1-q}$. Our main result holds
whenever $m=2$, and also for {\em generic} $m\le n$ in every dimension $n\ge
3$, as long as the wells $SO(n)A_1,..., SO(n)A_m$ satisfy a certain
connectivity condition. These conclusions are mostly known when $n=2$, and they
are new for $n\ge 3$.


title: On the Lamperti stable processes

abstract:
  We consider a new family of $\R^d$-valued L\'{e}vy processes that we call
Lamperti stable. One of the advantages of this class is that the law of many
related functionals can be computed explicitely (see for instance \cite{cc},
\cite{ckp}, \cite{kp} and \cite{pp}). This family of processes shares many
properties with the tempered stable and the layered stable processes, defined
in Rosi\'nski \cite{ro} and Houdr\'e and Kawai \cite{hok} respectively, for
instance their short and long time behaviour. Additionally, in the real valued
case we find a series representation which is used for sample paths simulation.
In this work we find general properties of this class and we also provide many
examples, some of which appear in recent literature.


title:
Quaternion polar representation with a complex modulus and complex
  argument inspired by the Cayley-Dickson form

abstract:
  We present a new polar representation of quaternions inspired by the
Cayley-Dickson representation. In this new polar representation, a quaternion
is represented by a pair of complex numbers as in the Cayley-Dickson form, but
here these two complex numbers are a complex 'modulus' and a complex
'argument'. As in the Cayley-Dickson form, the two complex numbers are in the
same complex plane (using the same complex root of -1), but the complex phase
is multiplied by a different complex root of -1 in the exponential function. We
show how to calculate the amplitude and phase from an arbitrary quaternion in
Cartesian form.


title:
The moduli space of \'etale double covers of genus 5 curves is
  unirational

abstract:
  We show that the coarse moduli space $\cR_5$ of \'etale double covers of
curves of genus~5 over the complex numbers is unirational. We give two slightly
different arguments, one purely geometric and the other more computational.


title:
On the Presence of Water and Global Circulation in the Transiting Planet
  HD 189733b

abstract:
  Detailed models are compared to recent infrared observations of the nearby
extrasolar planet, HD 189733b. It is demonstrated that atmospheric water is
present and that the planet's day side has a non-isothermal structure down to
gas pressures of ~ 0.1 bars. Furthermore, model spectra with different amounts
of CO are compared to the observations and an atmosphere absent of CO is
excluded at roughly 2-sigma. Constraining the CO concentration beyond that is
unfortunately not possible with the current Spitzer photometry. However,
radically enhanced (or depleted) metal abundances are unlikely and the basic
composition of this planet is probably similar to that of its host star. When
combined with Spitzer observations, a recent ground-based upper limit for the
K-band day side flux allows one to estimate the day-to-night energy
redistribution efficiency to be ~ 43%.


title:
A Criterion for Attaining the Welch Bounds with Applications for
  Mutually Unbiased Bases

abstract:
  The paper gives a short introduction to mutually unbiased bases and the Welch
bounds and demonstrates that the latter is a good technical tool to explore the
former. In particular, a criterion for a system of vectors to satisfy the Welch
bounds with equality is given and applied for the case of MUBs. This yields a
necessary and sufficient condition on a set of orthonormal bases to form a
complete system of MUBs.
  This condition takes an especially elegant form in the case of homogeneous
systems of MUBs. We express some known constructions of MUBs in this form. Also
it is shown how recently obtained results binding MUBs and some combinatorial
structures (such as perfect nonlinear functions and relative difference sets)
naturally follow from this criterion.
  Some directions for proving non-existence results are sketched as well.


title: Horizontal Heegaard splittings of Seifert fibered spaces

abstract:
  We show that if an orientable Seifert fibered space $M$ with an orientable
genus $g$ base space admits a strongly irreducible horizontal Heegaard
splitting then there is a one-to-one correspondence between isotopy classes of
strongly irreducible horizontal Heegaard splittings and elements of
$\mathbf{Z}^{2g}$. The correspondence is determined by the slopes of
intersection of each Heegaard splitting with a collection of $2g$
incompressible tori in $M$. We also show that there are Seifert fibered spaces
with infinitely many non-isotopic Heegaard splittings that determine Nielsen
equivalent generating systems for the fundamental group of $M$.


title:
Narrow-line magneto-optical cooling and trapping of strongly magnetic
  atoms

abstract:
  Laser cooling on weak transitions is a useful technique for reaching
ultracold temperatures in atoms with multiple valence electrons. However, for
strongly magnetic atoms a conventional narrow-line magneto-optical trap (MOT)
is destabilized by competition between optical and magnetic forces. We overcome
this difficulty in Er by developing an unusual narrow-line MOT that balances
optical and magnetic forces using laser light tuned to the blue side of a
narrow (8 kHz) transition. The trap population is spin-polarized with
temperatures reaching below 2 microkelvin. Our results constitute an
alternative method for laser cooling on weak transitions, applicable to
rare-earth-metal and metastable alkaline earth elements.


title:
Semi-classical limits of the first eigenfunction and concentration on
  the recurrent sets of a dynamical system

abstract:
  Dear Reader, please find the third and last part of a series of papers on the
singular perturbation of the first eigenfunction associated to a non
self-adjoint second order elliptic operators. This series started in 1999 and
we presented the early results in 2000 at Columbia University. We published two
notes in CRAS in 2001 and 2005 summarizing our results. The present paper
contains the proofs of the announced theorems and many open questions. We tried
to publish these results in the the top tier of mathematical journals (Annals,
Acta, Duke...) but our results were not deemed sufficiently interesting for
them and probably not trendy enough. Some of you may like this work, so here it
is. Best Regards, Ivan and David.
  We study the semi-classical limits of the first eigenfunction of a positive
second order operator on a compact Riemannian manifold, when the diffusion
constant $\epsilon$ goes to zero. If the drift of the diffusion is given by a
Morse-Smale vector field $b$, the limits of the eigenfunctions concentrate on
the recurrent set of $b$. A blow-up analysis enables us to find the main
properties of the limit measures on a recurrent set.


title:
Analytical Estimate of the Effect of Spherical Inhomogeneities on
  Luminosity Distance and Redshift

abstract:
  We provide an analytical estimate of the effect of a spherical inhomogeneity
on light beams that travel through it. We model the interior of the
inhomogeneity in terms of the Lemaitre-Tolman-Bondi metric. We assume that the
beam source is located outside the inhomogeneity. We study the relative
deviations of travelling time, redshift, beam area and luminosity distance from
their values in a homogeneous cosmology. They depend on the ratio Hb=H r_0 of
the radius r_0 of the inhomogeneity to the horizon distance 1/H. For an
observer located at the center, the deviations are of order Hb^2. For an
observer outside the inhomogeneity, the deviations of crossing time and
redshift are of order Hb^3. The deviations of beam area and luminosity distance
are of order Hb^2. However, when averaged over all possible locations of the
observer outside the inhomogeneity, they also become of order Hb^3. We discuss
the implications for the possibility of attributing the observed cosmological
acceleration to the emergence of large-scale structure.


title:
MaGe - a Geant4-based Monte Carlo framework for low-background
  experiments

abstract:
  A Monte Carlo framework, MaGe, has been developed based on the Geant4
simulation toolkit. Its purpose is to simulate physics processes in low-energy
and low-background radiation detectors, specifically for the Majorana and Gerda
$^{76}$Ge neutrinoless double-beta decay experiments. This jointly-developed
tool is also used to verify the simulation of physics processes relevant to
other low-background experiments in Geant4. The MaGe framework contains
simulations of prototype experiments and test stands, and is easily extended to
incorporate new geometries and configurations while still using the same
verified physics processes, tunings, and code framework. This reduces
duplication of efforts and improves the robustness of and confidence in the
simulation output.


title: Using Bayesian Blocks to Partition Self-Organizing Maps

abstract:
  Self organizing maps (SOMs) are widely-used for unsupervised classification.
For this application, they must be combined with some partitioning scheme that
can identify boundaries between distinct regions in the maps they produce. We
discuss a novel partitioning scheme for SOMs based on the Bayesian Blocks
segmentation algorithm of Scargle [1998]. This algorithm minimizes a cost
function to identify contiguous regions over which the values of the attributes
can be represented as approximately constant. Because this cost function is
well-defined and largely independent of assumptions regarding the number and
structure of clusters in the original sample space, this partitioning scheme
offers significant advantages over many conventional methods. Sample code is
available.


title:
O(a) improvement of the HYP static axial and vector currents at one-loop
  order of perturbation theory

abstract:
  We calculate analytically the improvement coefficients of the static axial
and vector currents in O(a) improved lattice QCD at one-loop order of
perturbation theory. The static quark is described by the hypercubic action,
previously introduced in the literature in order to improve the signal-to-noise
ratio of static observables. Within a Schroedinger Functional setup, we derive
the Feynman rules of the hypercubic link in time-momentum representation. The
improvement coefficients are obtained from on-shell correlators of the static
axial and vector currents. As a by-product, we localise the minimum of the
static self-energy as a function of the smearing parameters of the action at
one-loop order and show that the perturbative minimum is close to its
non-perturbative counterpart.


title: Nucleon structure with two flavors of dynamical domain-wall fermions

abstract:
  We present a numerical lattice quantum chromodynamics calculation of
isovector form factors and the first few moments of the isovector structure
functions of the nucleon. The calculation employs two degenerate dynamical
flavors of domain-wall fermions, resulting in good control of chiral symmetry
breaking. Non-perturbative renormalization of the relevant quark currents is
performed where necessary. The inverse lattice spacing, $a^{-1}$, is about 1.7
GeV. We use degenerate up and down dynamical quark masses around 1, 3/4 and 1/2
the strange quark mass. The physical volume of the lattice is about
$(1.9{fm})^3$. The ratio of the isovector vector to axial charges, $g_A/g_V$,
trends a bit lower than the experimental value as the quark mass is reduced
toward the physical point. We calculate the momentum-transfer dependences of
the isovector vector, axial, induced tensor and induced pseudoscalar form
factors. The Goldberger-Treiman relation holds at low momentum transfer and
yields a pion-nucleon coupling, $g_{\pi NN} = 15.5(1.4)$, where the quoted
error is only statistical. We find that the flavor non-singlet quark momentum
fraction $<x>_{u-d}$ and quark helicity fraction $<x>_{\Delta u-\Delta d}$
overshoot their experimental values after linear chiral extrapolation. We
obtain the transversity, $<1 >_{\delta u-\delta d} = 0.93(6)$ in $\bar{\rm MS}$
at 2 GeV and a twist-3 polarized moment, $d_1$, appears small, suggesting that
the Wandzura-Wilczek relation holds approximately. We discuss the systematic
errors in the calculation, with particular attention paid to finite-volume
effects, excited-state contamination, and chiral extrapolations.


title: Area-angle variables for general relativity

abstract:
  We introduce a modified Regge calculus for general relativity on a
triangulated four dimensional Riemannian manifold where the fundamental
variables are areas and a certain class of angles. These variables satisfy
constraints which are local in the triangulation. We expect the formulation to
have applications to classical discrete gravity and non-perturbative approaches
to quantum gravity.


title: Combining generic judgments with recursive definitions

abstract:
  Many semantical aspects of programming languages, such as their operational
semantics and their type assignment calculi, are specified by describing
appropriate proof systems. Recent research has identified two proof-theoretic
features that allow direct, logic-based reasoning about such descriptions: the
treatment of atomic judgments as fixed points (recursive definitions) and an
encoding of binding constructs via generic judgments. However, the logics
encompassing these two features have thus far treated them orthogonally: that
is, they do not provide the ability to define object-logic properties that
themselves depend on an intrinsic treatment of binding. We propose a new and
simple integration of these features within an intuitionistic logic enhanced
with induction over natural numbers and we show that the resulting logic is
consistent. The pivotal benefit of the integration is that it allows recursive
definitions to not just encode simple, traditional forms of atomic judgments
but also to capture generic properties pertaining to such judgments. The
usefulness of this logic is illustrated by showing how it can provide elegant
treatments of object-logic contexts that appear in proofs involving typing
calculi and of arbitrarily cascading substitutions that play a role in
reducibility arguments.


title: Stronger constraints on non-Newtonian gravity from the Casimir effect

abstract:
  We review new constraints on the Yukawa-type corrections to Newtonian gravity
obtained recently from gravitational experiments and from the measurements of
the Casimir force. Special attention is paid to the constraints following from
the most precise dynamic determination of the Casimir pressure between the two
parallel plates by means of a micromechanical torsional oscillator. The
possibility of setting limits on the predictions of chameleon field theories
using the results of gravitational experiments and Casimir force measurements
is discussed.


title:
X-ray photoelectron emission microscopy in combination with x-ray
  magnetic circular dichroism investigation of size effects on field-induced
  N\'eel-cap reversal

abstract:
  X-ray photoelectron emission microscopy in combination with x-ray magnetic
circular dichroism is used to investigate the influence of an applied magnetic
field on N\'eel caps (i.e., surface terminations of asymmetric Bloch walls).
Self-assembled micron-sized Fe(110) dots displaying a moderate distribution of
size and aspect ratios serve as model objects. Investigations of remanent
states after application of an applied field along the direction of N\'eel-cap
magnetization give clear evidence for the magnetization reversal of the N\'eel
caps around 120 mT, with a $\pm$20 mT dispersion. No clear correlation could be
found between the value of the reversal field and geometrical features of the
dots.


title: Explicit Cancellation of Triangles in One-loop Gravity Amplitudes

abstract:
  We analyse one-loop graviton amplitudes in the field theory limit of a
genus-one string theory computation. The considered amplitudes can be
dimensionally reduced to lower dimensions preserving maximal supersymmetry. The
particular case of the one-loop five-graviton amplitude is worked out in detail
and explicitly features no triangle contributions. Based on a recursive form of
the one-loop amplitude we investigate the contributions that will occur at
n-point order in relation to the ``no-triangle'' hypothesis of N=8
supergravity. We argue that the origin of unexpected cancellations observed in
gravity scattering amplitudes is linked to general coordinate invariance of the
gravitational action and the summation over all orderings of external legs.
Such cancellations are instrumental in the extraordinary good ultra-violet
behaviour of N=8 supergravity amplitudes and will play a central role in
improving the high-energy behaviour of gravity amplitudes at more than one
loop.


title:
Optimal control of impulsive Volterra equations with variable impulse
  times

abstract:
  We obtain necessary conditions of optimality for impulsive Volterra integral
equations with switching and impulsive controls, with variable impulse
time-instants. The present work continues and complements our previous work on
impulsive Volterra control with fixed impulse times.


title: Building all Time Evolutions with Rotationally Invariant Hamiltonians

abstract:
  All elementary Hamiltonians in nature are expected to be invariant under
rotation. Despite this restriction, we usually assume that any arbitrary
measurement or unitary time evolution can be implemented on a physical system,
an assumption whose validity is not obvious. We introduce two different schemes
by which any arbitrary unitary time evolution and measurement can be
implemented with desired accuracy by using rotationally invariant Hamiltonians
that act on the given system and two ancillary systems serving as reference
frames. These frames specify the z and x directions and are independent of the
desired time evolution. We also investigate the effects of quantum fluctuations
that inevitably arise due to usage of a finite system as a reference frame and
estimate how fast these fluctuations tend to zero when the size of the
reference frame tends to infinity. Moreover we prove that for a general
symmetry any symmetric quantum operations can be implemented just by using
symmetric interactions and ancillas in the symmetric states.


title:
The spectrum of the Broad Line Region and the high-energy emission of
  powerful blazars

abstract:
  High-energy emission (from the X-ray through the gamma-ray band) of Flat
Spectrum Radio Quasars is widely associated with the inverse Compton (IC)
scattering of ambient photons, produced either by the accretion disk or by the
Broad Line Region, by high-energy electrons in a relativistic jet. In the
modelling of the IC spectrum one usually adopts a simple black-body
approximation for the external radiation field, though the real shape is
probably more complex. The knowledge of the detailed spectrum of the external
radiation field would allow to better characterize the soft-medium X-ray IC
spectrum, which is crucial to address several issues related to the study of
these sources. Here we present a first step in this direction, calculating the
IC spectra expected by considering a realistic spectrum for the external
radiation energy density produced by the BLR, as calculated with the
photoionization code CLOUDY. We find that, under a wide range of the physical
parameters characterizing the BLR clouds, the IC spectrum calculated with the
black-body approximation reproduces quite well the exact spectrum for energies
above few keV. In the soft energy band, instead, the IC emission calculated
using the BLR emission shows a complex shape, with a moderate excess with
respect to the approximate spectrum, which becomes more important for
decreasing values of the peak frequency of the photoionizing continuum. We also
show that the high-energy spectrum shows a marked steepening, due to the energy
dependence of the scattering cross section, above a characteristic energy of
10-20 GeV, quasi independent on the Lorentz factor of the jet.


title: On the Origin of Dynamically Cold Rings Around the Milky Way

abstract:
  We present a scenario for the production of dynamically cold rings around the
Milky Way via a high-eccentricity, flyby encounter. These initial conditions
are more cosmologically motivated than those considered in previous works. We
find that the encounters we examine generically produce a series of nearly
dynamically cold ring-like features on low-eccentricity orbits that persist
over timescales of ~2-4 Gyr via the tidal response of the primary galaxy to the
close passage of the satellite. Moreover, they are both qualitatively and
quantitatively similar to the distribution, kinematics, and stellar population
of the Monoceros ring. Therefore, we find that a high eccentricity flyby by a
satellite galaxy represents a cosmologically appealing scenario for forming
kinematically distinct ring-like features around the Milky Way.


title: Subleading Shape-Function Effects and the Extraction of |V_ub|

abstract:
  We derive a class of formulae relating moments of B -> Xu l nu to B -> Xs
gamma in the shape function region, where m_X^2 ~ m_b Lambda_QCD. We also
derive an analogous class of formulae involving the decay B -> Xs l+ l-. These
results incorporate Lambda_QCD/m_b power corrections, but are independent of
leading and subleading hadronic shape functions. Consequently, they enable one
to determine |V_ub|/|V_tb V_ts*| to subleading order in a model-independent
way.


title:
GRBs 070429B and 070714B: The High End of the Short-Duration Gamma-Ray
  Burst Redshift Distribution

abstract:
  We present optical spectra of the host galaxies of the short-duration
gamma-ray burst GRB 070429B and the likely short-duration with extended
emission GRB 070714B. In both cases, we find a single emission line that we
identify as O II lambda 3727 at z ~ 0.9. Both events are more distant than any
previous short-duration GRB with a secure host association from the
sub-arcsecond position of an optical afterglow. GRBs 070429B and 070714B
provide strong evidence in support of our previous claims in Berger et al. that
a significant fraction of short-duration hosts (>~ 33%) reside at z > 0.7. We
discuss the implications of the existence this population on the energetics of
short-duration GRBs, as well as on progenitor models. In the context of the
degenerate binary merger scenario, such events require progenitor systems with
a range of lifetimes and disfavor progenitor models with a long, narrow
lifetime distribution.