title: Heat conduction in 2D strongly-coupled dusty plasmas

abstract:
  We perform non-equilibrium simulations to study heat conduction in
two-dimensional strongly coupled dusty plasmas. Temperature gradients are
established by heating one part of the otherwise equilibrium system to a higher
temperature. Heat conductivity is measured directly from the stationary
temperature profile and heat flux. Particular attention is paid to the
influence of damping effect on the heat conduction. It is found that the heat
conductivity increases with the decrease of the damping rate, while its
magnitude agrees with previous experimental measurement.


title: Peer-to-Peer Secure Multi-Party Numerical Computation

abstract:
  We propose an efficient framework for enabling secure multi-party numerical
computations in a Peer-to-Peer network. This problem arises in a range of
applications such as collaborative filtering, distributed computation of trust
and reputation, monitoring and numerous other tasks, where the computing nodes
would like to preserve the privacy of their inputs while performing a joint
computation of a certain function.
  Although there is a rich literature in the field of distributed systems
security concerning secure multi-party computation, in practice it is hard to
deploy those methods in very large scale Peer-to-Peer networks. In this work,
we examine several possible approaches and discuss their feasibility. Among the
possible approaches, we identify a single approach which is both scalable and
theoretically secure.
  An additional novel contribution is that we show how to compute the
neighborhood based collaborative filtering, a state-of-the-art collaborative
filtering algorithm, winner of the Netflix progress prize of the year 2007. Our
solution computes this algorithm in a Peer-to-Peer network, using a privacy
preserving computation, without loss of accuracy.
  Using extensive large scale simulations on top of real Internet topologies,
we demonstrate the applicability of our approach. As far as we know, we are the
first to implement such a large scale secure multi-party simulation of networks
of millions of nodes and hundreds of millions of edges.


title: Volatility Effects on the Escape Time in Financial Market Models

abstract:
  We shortly review the statistical properties of the escape times, or hitting
times, for stock price returns by using different models which describe the
stock market evolution. We compare the probability function (PF) of these
escape times with that obtained from real market data. Afterwards we analyze in
detail the effect both of noise and different initial conditions on the escape
time in a market model with stochastic volatility and a cubic nonlinearity. For
this model we compare the PF of the stock price returns, the PF of the
volatility and the return correlation with the same statistical characteristics
obtained from real market data.


title: Detection of chromatic microlensing in Q 2237+0305 A

abstract:
  We present narrowband images of the gravitational lens system Q~2237+0305
made with the Nordic Optical Telescope in eight different filters covering the
wavelength interval 3510-8130 \AA. Using point-spread function photometry
fitting we have derived the difference in magnitude versus wavelength between
the four images of Q~2237+0305. At $\lambda=4110$ \AA, the wavelength range
covered by the Str\"omgren-v filter coincides with the position and width of
the CIV emission line. This allows us to determine the existence of
microlensing in the continuum and not in the emission lines for two images of
the quasar. Moreover, the brightness of image A shows a significant variation
with wavelength which can only be explained as consequence of chromatic
microlensing. To perform a complete analysis of this chromatic event our
observations were used together with Optical Gravitational Lensing Experiment
light curves. Both data sets cannot be reproduced by the simple phenomenology
described under the caustic crossing approximation; using more realistic
representations of microlensing at high optical depth, we found solutions
consistent with simple thin disk models ($r_{s}\varpropto \lambda^{4/3}$);
however, other accretion disk size-wavelength relationships also lead to good
solutions. New chromatic events from the ongoing narrow band photometric
monitoring of Q~2237+0305 are needed to accurately constrain the physical
properties of the accretion disk for this system.


title: Interlaced linear-nonlinear optical waveguide arrays

abstract:
  The system of coupled discrete equations describing a two-component
superlattice with interlaced linear and nonlinear constituents is revisited as
a basis for investigating binary waveguide arrays, such as ribbed AlGaAs
structures, among others. Compared to the single nonlinear lattice, the
interlaced system exhibits an extra band-gap controlled by the, suitably chosen
by design, relative detuning. In more general physics settings, this system
represents a discretization scheme for the single-equation-based continuous
models in media with transversely modulated linear and nonlinear properties.
Continuous wave solutions and the associated modulational instability are fully
analytically investigated and numerically tested for focusing and defocusing
nonlinearity. The propagation dynamics and the stability of periodic modes are
also analytically investigated for the case of zero Bloch momentum. In the
band-gaps a variety of stable discrete solitary modes, dipole or otherwise,
in-phase or of staggered type are found and discussed.


title: Distributed Kalman Filter via Gaussian Belief Propagation

abstract:
  Recent result shows how to compute distributively and efficiently the linear
MMSE for the multiuser detection problem, using the Gaussian BP algorithm. In
the current work, we extend this construction, and show that operating this
algorithm twice on the matching inputs, has several interesting
interpretations. First, we show equivalence to computing one iteration of the
Kalman filter. Second, we show that the Kalman filter is a special case of the
Gaussian information bottleneck algorithm, when the weight parameter $\beta =
1$. Third, we discuss the relation to the Affine-scaling interior-point method
and show it is a special case of Kalman filter.
  Besides of the theoretical interest of this linking estimation,
compression/clustering and optimization, we allow a single distributed
implementation of those algorithms, which is a highly practical and important
task in sensor and mobile ad-hoc networks. Application to numerous problem
domains includes collaborative signal processing and distributed allocation of
resources in a communication network.


title:
Does the universe obey the energy conservation law by a constant mass or
  an increasing mass with radius during its evolution?

abstract:
  How the energy conservation law is obeyed by the universe during its
evolution is an important but not yet unanimously resolved question. Does the
universe have a constant mass during its evolution or has its mass been
increasing with its radius? Here, we evaluate the two contending propositions
within the context of the Friedmann equations and the standard big bang theory.
We find that though both propositions appeal to the Friedmann equations for
validity, an increasing mass with increasing radius is more in harmony with the
thermal history of the big bang model. In addition, temperature and flatness
problems that plague the constant mass proposal are mitigated by the increasing
mass with radius proposal. We conclude that the universe has been increasing in
mass and radius in obedience to the energy conservation law.


title: Attributing sense to some integrals in Regge calculus

abstract:
  Regge calculus minisuperspace action in the connection representation has the
form in which each term is linear over some field variable (scale of area-type
variable with sign). We are interested in the result of performing integration
over connections in the path integral (now usual multiple integral) as function
of area tensors even in larger region considered as independent variables. To
find this function (or distribution), we compute its moments, i. e. integrals
with monomials over area tensors. Calculation proceeds through intermediate
appearance of $\delta$-functions and integrating them out. Up to a singular
part with support on some discrete set of physically unattainable points, the
function of interest has finite moments. This function in physical region
should therefore exponentially decay at large areas and it really does being
restored from moments. This gives for gravity a way of defining such
nonabsolutely convergent integral as path integral.


title: Polynomial Linear Programming with Gaussian Belief Propagation

abstract:
  Interior-point methods are state-of-the-art algorithms for solving linear
programming (LP) problems with polynomial complexity. Specifically, the
Karmarkar algorithm typically solves LP problems in time O(n^{3.5}), where $n$
is the number of unknown variables. Karmarkar's celebrated algorithm is known
to be an instance of the log-barrier method using the Newton iteration. The
main computational overhead of this method is in inverting the Hessian matrix
of the Newton iteration. In this contribution, we propose the application of
the Gaussian belief propagation (GaBP) algorithm as part of an efficient and
distributed LP solver that exploits the sparse and symmetric structure of the
Hessian matrix and avoids the need for direct matrix inversion. This approach
shifts the computation from realm of linear algebra to that of probabilistic
inference on graphical models, thus applying GaBP as an efficient inference
engine. Our construction is general and can be used for any interior-point
algorithm which uses the Newton method, including non-linear program solvers.


title: Large localizations of finite groups

abstract:
  We construct examples of localizations in the category of groups which take
the Mathieu group $M_{11}$ to groups of arbitrarily large cardinality which are
``abelian up to finitely many generators''. The paper is part of a broader
study on the group theoretic properties which are or are not preserved by
localizations.


title: Comments on Baryons in Holographic QCD

abstract:
  We generalize the description of baryons as instantons of Sakai-Sugimoto
model to the case where the flavor branes are non-anti-podal. The later
corresponds to quarks with a "string endpoint mass". We show that the baryon
vertex is located on the flavor branes and hence the generalized baryons also
associate with instantons. We calculate the baryon mass spectra, the isoscalar
and axial mean square radii, the isoscalar and isovector magnetic moments and
the axial coupling as a function of the mass scale M_{KK} and the location
\zeta of the tip of U-shaped flavor D8-branes. We determine the values of
M_{KK} and \zeta from a best fit comparison with the experimental data. The
later comes out to be in a forbidden region, which may indicate that the
incorporation of baryons in Sakai-Sugimoto model has to be modified. We discuss
the analogous baryons in a non-critical gravity model. A brief comment on the
single flavor case (N_f=1) is also made.


title:
Optical pulse propagation in a switched-on photonic lattice: Rabi effect
  with the roles of light and matter interchanged

abstract:
  A light pulse propagating in a suddenly switched on photonic lattice, when
the central frequency lies in the photonic band gap, is an analog of the Rabi
model where the two-level system is the two resonant (i.e. Bragg-coupled)
Fourier modes of the pulse, while the photonic lattice serves as a
monochromatic external field. A simple theory of these Rabi oscillations is
given and confirmed by the numerical solution of the corresponding Maxwell
equations. This is a direct, i.e. temporal, analog of the Rabi effect,
additionally to the spatial analog in optical beam propagation described in
Opt. Lett. 32, 1920 (2007). An additional high-frequency modulation of the Rabi
oscillations reflects the lattice-induced energy transfer between the electric
and magnetic fields of the pulse.


title: Spatiotemporal interaction of optical beams in bi-dispersive media

abstract:
  The interaction of optical beams in bi-dispersive nonlinear media with
self-focusing nonlinearity is numerically investigated. Under proper
conditions, the interaction of spatially separated beams can lead to the
creation of two prominent filaments along the other spatial or temporal
dimension and, thus to an effective beam exchange. This X-wave generation-based
effect could potentially be exploited in optical realizations of spatial or
spatio-temporal filtering.


title: Warp and eccentricity propagation in discs around black holes

abstract:
  We consider the inward propagation of warping and eccentric disturbances in
discs around black holes under a wide variety of conditions. In our
calculations we use secular theories of warped and eccentric discs and assume
the deformations to be stationary and propagating in a disc model similar to
regions (a) and (b) of Shakura and Sunyaev discs. We find that the propagation
of deformations to the innermost regions of the disc is facilitated for low
viscous damping and high accretion rate. We relate our results to the possible
excitation of trapped inertial modes, and to the observations of high-frequency
quasi-periodic oscillations (QPOs) in black hole systems in the very high
spectral state.


title: Pulsar Timing for the Fermi Gamma-ray Space Telescope

abstract:
  We describe a comprehensive pulsar monitoring campaign for the Large Area
Telescope (LAT) on the {\em Fermi Gamma-ray Space Telescope} (formerly GLAST).
The detection and study of pulsars in gamma rays give insights into the
populations of neutron stars and supernova rates in the Galaxy, into particle
acceleration mechanisms in neutron star magnetospheres, and into the "engines"
driving pulsar wind nebulae. LAT's unprecedented sensitivity between 20 MeV and
300 GeV together with its 2.4 sr field-of-view makes detection of many
gamma-ray pulsars likely, justifying the monitoring of over two hundred pulsars
with large spin-down powers. To search for gamma-ray pulsations from most of
these pulsars requires a set of phase-connected timing solutions spanning a
year or more to properly align the sparse photon arrival times. We describe the
choice of pulsars and the instruments involved in the campaign. Attention is
paid to verifications of the LAT pulsar software, using for example giant radio
pulses from the Crab and from PSR B1937+21 recorded at Nan\c{c}ay, and using
X-ray data on PSR J0218+4232 from XMM-Newton. We demonstrate accuracy of the
pulsar phase calculations at the microsecond level. Data Table 1 is only
available in electronic form at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/ .


title: On the existence of shortest directed networks

abstract:
  A directed network connecting a set A to a set B is a digraph containing an
a-b path for each a in A and b in B. Vertices in the directed network not in A
or B are called Steiner points. We show that in a finitely compact metric space
in which geodesics exist, any two finite sets A and B are connected by a
shortest directed network. We also bound the number of Steiner points by a
function of the sizes of A and B. Previously, such an existence result was
known only for the Euclidean plane [M. Alfaro, Pacific J. Math. 167 (1995)
201-214]. The main difficulty is that, unlike the undirected case (Steiner
minimal trees), the underlying graphs need not be acyclic.
  Existence in the undirected case was first shown by E. J. Cockayne [Canad.
Math. Bull. 10 (1967) 431-450].


title: Identifying almost sorted permutations from TCP buffer dynamics

abstract:
  Associate to each sequence $A$ of integers (intending to represent packet
IDs) a sequence of positive integers of the same length ${\mathcal M}(A)$. The
$i$'th entry of ${\mathcal M}(A)$ is the size (at time $i$) of the smallest
buffer needed to hold out-of-order packets, where space is accounted for
unreceived packets as well. Call two sequences $A$, $B$ {\em equivalent}
(written $A\equiv_{FB} B$) if ${\mathcal M}(A)={\mathcal M}(B)$.
  We prove the following result: any two permutations $A,B$ of the same length
with $SUS(A)$, $SUS(B)\leq 3$ (where SUS is the {\em shuffled-up-sequences}
reordering measure), and such that $A\equiv_{FB} B$ are identical.
  The result (which is no longer valid if we replace the upper bound 3 by 4)
was motivated by RESTORED, a receiver-oriented model of network traffic we have
previously introduced.


title:
On finiteness and rigidity of J-holomorphic curves in symplectic
  three-folds

abstract:
  Given a symplectic three-fold $(M,\omega)$ we show that for a generic almost
complex structure $J$ which is compatible with $\omega$, there are finitely
many $J$-holomorphic curves in $M$ of any genus $g\geq 0$ representing a
homology class $\beta$ in $\H_2(M,\Z)$ with $c_1(M).\beta=0$, provided that the
divisibility of $\beta$ is at most 4 (i.e. if $\beta=n\alpha$ with $\alpha\in
H_2(M,\Z)$ and $n\in \Z$ then $n\leq 4$). Moreover, each such curve is embedded
and 4-rigid.


title:
Electron Spin Resonance across the Charge-ordering Transition in
  YBaMn2O6

abstract:
  We investigated the metal-ordered manganite system YBaMn2O6 using electron
spin resonance (ESR) in the paramagnetic regime across the charge-ordering and
structural phase transition at T_CO = 480 K and T_t = 520 K, respectively. All
ESR parameters exhibit jump-like changes at T_t while the charge-ordering at
T_CO manifests itself only as a weak and broad anomaly. Above T_t the ESR spin
susceptibility is reduced with respect to the dc-susceptibility, indicating
that only the t_2g-core spins of Mn ions contribute to the resonance
absorption. The contribution of the e_g-spins is suppressed by the time scale
of the polaronic hopping process of the e_g-electrons. The linewidth in this
regime is reminiscent of a Korringa-type relaxation behavior. In this picture
the ESR properties below T_t are dominated by the slowing down of the polaronic
hopping process. The charge fluctuations persist down to the temperature T* ~
410 K, below which the system can be described as a charge-ordered assembly of
Mn$^{3+}$ and Mn$^{4+}$ spins.


title:
Massive Dirac particles on the background of charged de-Sitter black
  hole manifolds

abstract:
  We consider the behavior of massive Dirac fields on the background of a
charged de-Sitter black hole. All black hole geometries are taken into account,
including the Reissner-Nordstr\"{o}m-de-Sitter one, the Nariai case and the
ultracold case. Our focus is at first on the existence of bound quantum
mechanical states for the Dirac Hamiltonian on the given backgrounds. In this
respect, we show that in all cases no bound state is allowed, which amounts
also to the non-existence of normalizable time-periodic solutions of the Dirac
equation. This quantum result is in contrast to classical physics, and it is
shown to hold true even for extremal cases. Furthermore, we shift our attention
on the very interesting problem of the quantum discharge of the black holes.
Following Damour-Deruelle-Ruffini approach, we show that the existence of
level-crossing between positive and negative continuous energy states is a
signal of the quantum instability leading to the discharge of the black hole,
and in the cases of the Nariai geometry and of the ultracold geometries we also
calculate in WKB approximation the transmission coefficient related to the
discharge process.


title: Lelek's problem is not a metric problem

abstract:
  We show that Lelek's problem on the chainability of continua with span zero
is not a metric problem: from a non-metric counterexample one can construct a
metric one.


title:
Some Two-Step Procedures for Variable Selection in High-Dimensional
  Linear Regression

abstract:
  We study the problem of high-dimensional variable selection via some two-step
procedures. First we show that given some good initial estimator which is
$\ell_{\infty}$-consistent but not necessarily variable selection consistent,
we can apply the nonnegative Garrote, adaptive Lasso or hard-thresholding
procedure to obtain a final estimator that is both estimation and variable
selection consistent. Unlike the Lasso, our results do not require the
irrepresentable condition which could fail easily even for moderate $p_n$ (Zhao
and Yu, 2007) and it also allows $p_n$ to grow almost as fast as $\exp(n)$ (for
hard-thresholding there is no restriction on $p_n$). We also study the
conditions under which the Ridge regression can be used as an initial
estimator. We show that under a relaxed identifiable condition, the Ridge
estimator is $\ell_{\infty}$-consistent. Such a condition is usually satisfied
when $p_n\le n$ and does not require the partial orthogonality between relevant
and irrelevant covariates which is needed for the univariate regression in
(Huang et al., 2008). Our numerical studies show that when using the Lasso or
Ridge as initial estimator, the two-step procedures have a higher sparsity
recovery rate than the Lasso or adaptive Lasso with univariate regression used
in (Huang et al., 2008).


title: Atomistic spin dynamics of the CuMn spin glass alloy

abstract:
  We demonstrate the use of Langevin spin dynamics for studying dynamical
properties of an archetypical spin glass system. Simulations are performed on
CuMn (20% Mn) where we study the relaxation that follows a sudden quench of the
system to the low temperature phase. The system is modeled by a Heisenberg
Hamiltonian where the Heisenberg interaction parameters are calculated by means
of first-principles density functional theory. Simulations are performed by
numerically solving the Langevin equations of motion for the atomic spins. It
is shown that dynamics is governed, to a large degree, by the damping parameter
in the equations of motion and the system size. For large damping and large
system sizes we observe the typical aging regime.


title: Conformally flat tangent bundles with general natural lifted metrics

abstract:
  We study the conditions under which the tangent bundle $(TM,G)$ of an
$n$-dimensional Riemannian manifold $(M,g)$ is conformally flat, where $G$ is a
general natural lifted metric of $g$. We prove that the base manifold must have
constant sectional curvature and we find some expressions for the natural
lifted metric $G$, such that the tangent bundle $(TM,G)$ become conformally
flat.


title:
ERBL and DGLAP kernels for transversity distributions. Two-loop
  calculations in covariant gauge

abstract:
  The results of a two-loop calculation in the Feynman gauge of both the DGLAP
and the ERBL evolution kernels for transversely polarized distributions are
presented. The structure of these evolution kernels is discussed in detail. In
addition, the effect of the two-loop evolution on the distribution amplitude of
a twist-2 transversely polarized meson is explored.


title:
A Gaussian Belief Propagation Solver for Large Scale Support Vector
  Machines

abstract:
  Support vector machines (SVMs) are an extremely successful type of
classification and regression algorithms. Building an SVM entails solving a
constrained convex quadratic programming problem, which is quadratic in the
number of training samples. We introduce an efficient parallel implementation
of an support vector regression solver, based on the Gaussian Belief
Propagation algorithm (GaBP).
  In this paper, we demonstrate that methods from the complex system domain
could be utilized for performing efficient distributed computation. We compare
the proposed algorithm to previously proposed distributed and single-node SVM
solvers. Our comparison shows that the proposed algorithm is just as accurate
as these solvers, while being significantly faster, especially for large
datasets. We demonstrate scalability of the proposed algorithm to up to 1,024
computing nodes and hundreds of thousands of data points using an IBM Blue Gene
supercomputer. As far as we know, our work is the largest parallel
implementation of belief propagation ever done, demonstrating the applicability
of this algorithm for large scale distributed computing systems.


title:
Fluctuations of the baryonic flux-tube junction from effective string
  theory

abstract:
  In quenched QCD, where the dynamic creation of quark-antiquark pairs out of
the vacuum is neglected, a confined baryonic system composed of three static
quarks exhibits string-like behaviour at large interquark separation, with the
formation of flux tubes characterized by the geometry of the so-called Y
ansatz. We study the fluctuations of the junction of the three flux tubes,
assuming the dynamics to be governed by an effective bosonic string model. We
show that the asymptotic behaviour of the effective width of the junction grows
logarithmically with the distance between the sources, with the coefficient
depending on the number of joining strings, on the dimension of spacetime and
on the string tension.


title: Demand allocation with latency cost functions

abstract:
  We address the exact resolution of a MINLP model where resources can be
activated in order to satisfy a demand (a partitioning constraint) while
minimizing total cost. Cost functions are convex latency functions plus a fixed
activation cost. A branch and bound algorithm is devised, featuring three
important characteristics. First, the lower bound (therefore each subproblem)
can be computed in O(nlog n). Second, to break symmetries resulting in improved
efficiency, the branching scheme is n-ary (instead of the "classical" binary).
Third, a very affective heuristic is used to compute a good upper bound at the
root node of the enumeration tree. All three features lead to a successful
comparison against CPLEX MIPQ, which is the fastest among several commercial
and open-source solvers: computational results showing this fact are provided.


title:
Atomic jets from class 0 sources detected by Spitzer: the case of
  L1448-C

abstract:
  We present Spitzer-IRS spectra obtained along the molecular jet from the
Class 0 source L1448-C (or L1448-mm). Atomic lines from the fundamental
transitions of [FeII], [SiII] and [SI] have been detected showing, for the
first time, the presence of an embedded atomic jet at low excitation. Pure
rotational H$_2$ lines are also detected, and a decrease of the
atomic/molecular emission ratio is observed within 1 arcmin from the driving
source. Additional ground based spectra (UKIRT/UIST) were obtained to further
constrain the H$_2$ excitation along the jet axis and, combined with the 0--0
lines, have been compared with bow-shock models. From the different line
ratios, we find that the atomic gas is characterized by an electron density n_e
~ 200-1000 cm^{-3}, a temperature T_e < 2500 K and an ionization fraction <~
10^{-2}; the excitation conditions of the atomic jet are thus very different
from those found in more evolved Class I and Class II jets. We also infer that
only a fraction (0.05-0.2) of Fe and Si is in gaseous form, indicating that
dust still plays a major role in the depletion of refractory elements. A
comparison with the SiO abundance recently derived in the jet from an analysis
of several SiO sub-mm transitions, shows that the Si/SiO abundance ratio is
~100, and thus that most of the silicon released from grains by sputtering and
grain-grain collisions remains in atomic form. Finally, estimates of the atomic
and molecular mass flux rates have been derived: values of the order of
~10$^{-6}$ and ~10$^{-7}$ M$_{\sun}$ yr$^{-1}$ are inferred from the
[SI]25$\mu$m and H$_2$ line luminosities, respectively. A comparison with the
momentum flux of the CO molecular outflow suggests that the detected atomic jet
has the power to drive the large scale outflow.


title:
The Holomorphic Sectional Curvature of General Natural K\"Ahler
  Structures on Cotangent Bundles

abstract:
  We study the conditions under which a K\"ahlerian structure $(G,J)$ of
general natural lift type on the cotangent bundle $T^*M$ of a Riemannian
manifold $(M,g)$ has constant holomorphic sectional curvature. We obtain that a
certain parameter involved in the condition for $(T^*M,G,J)$ to be a
K\"ahlerian manifold, is expressed as a rational function of the other two,
their derivatives, the constant sectional curvature of the base manifold
$(M,g)$, and the constant holomorphic sectional curvature of the general
natural K\"ahlerian structure $(G,J)$.


title: Evaluation of new spin foam vertex amplitudes with boundary states

abstract: Merged into arXiv:0809.3190.


title: Noise induced phenomena in point Josephson junctions

abstract:
  We present the analysis of the mean switching time and its standard deviation
of short overdamped Josephson junctions, driven by a direct current and a
periodic signal. The effect of noise enhanced stability is investigated. It is
shown that fluctuations may both decrease and increase the switching time.


title: On the Utility of Anonymized Flow Traces for Anomaly Detection

abstract:
  The sharing of network traces is an important prerequisite for the
development and evaluation of efficient anomaly detection mechanisms.
Unfortunately, privacy concerns and data protection laws prevent network
operators from sharing these data. Anonymization is a promising solution in
this context; however, it is unclear if the sanitization of data preserves the
traffic characteristics or introduces artifacts that may falsify traffic
analysis results. In this paper, we examine the utility of anonymized flow
traces for anomaly detection. We quantitatively evaluate the impact of IP
address anonymization, namely variations of permutation and truncation, on the
detectability of large-scale anomalies. Specifically, we analyze three weeks of
un-sampled and non-anonymized network traces from a medium-sized backbone
network. We find that all anonymization techniques, except prefix-preserving
permutation, degrade the utility of data for anomaly detection. We show that
the degree of degradation depends to a large extent on the nature and mix of
anomalies present in a trace. Moreover, we present a case study that
illustrates how traffic characteristics of individual hosts are distorted by
anonymization.


title: A Schmidt-Kennicutt law for star formation in the Milky Way disk

abstract:
  We use a new method to trace backwards the star formation history of the
Milky Way disk, using a sample of M dwarfs in the solar neighbourhood which is
representative for the entire solar circle. M stars are used because they show
H_alpha emission until a particular age which is a well calibrated function of
their absolute magnitudes. This allows us to reconstruct the rate at which disk
stars have been born over about half the disk's lifetime. Our star formation
rate agrees well with those obtained by using other, independent, methods and
seems to rule out a constant star formation rate.
  The principal result of this study is to show that a relation of the
Schmidt-Kennicut type (which relates the star formation rate to the
interstellar gas content of galaxy disks) has pertained in the Milky Way disk
during the last 5 Gyr. The star formation rate we derive from the M dwarfs and
the interstellar gas content of the disk can be inferred as a function of time
from a model of the chemical enrichment of the disk, which is well constrained
by the observations indicating that the metallicity of the Galactic disk has
remained nearly constant over the timescales involved. We demonstrate that the
star formation rate and gas surface densities over the last 5 Gyrs can be
accurately described by a Schmidt-Kennicutt law with an index of Gamma = 1.45
(+0.22,-0.09). This is, within statistical uncertainties, the same value found
for other galaxies.


title:
Measurement of the form factors of the decay B^0 -> D^{*-} l^+ nu_l and
  determination of the CKM matrix element |V_{cb}|

abstract:
  This paper describes a determination of the Cabibbo-Kobayashi-Maskawa matrix
element $|V_{cb}|$ using the decay $B^0\to D^{*-}\ell^+\nu_\ell$. We perform a
combined measurement of this quantity and of the form factors $\rho^2$,
$R_1(1)$, and $R_2(1)$ which fully characterize this decay in the framework of
heavy-quark effective theory, based on 140 fb$^{-1}$ of Belle data collected
near the $\Upsilon(4S)$ resonance. The results, based on about 69,000
reconstructed $B^0\to D^{*-}\ell^+\nu_\ell$ decays, are $\rho^2=1.293\pm
0.045\pm 0.029$, $R_1(1)=1.495\pm 0.050\pm 0.062$, $R_2(1)=0.844\pm 0.034\pm
0.019$ and $\mathcal{F}(1)|V_{cb}|=34.4\pm 0.2\pm 1.0$. The $B^0\to
D^{*-}\ell^+\nu_\ell$ branching fraction is found to be $(4.42\pm 0.03\pm
0.25)%$. For all these numbers, the first error is the statistical and the
second is the systematic uncertainty. All results are preliminary.


title: Radial Velocity Studies of Close Binary Stars. XIV

abstract:
  Radial-velocity measurements and sine-curve fits to the orbital radial
velocity variations are presented for ten close binary systems: TZ Boo, VW Boo,
EL Boo, VZ CVn, GK Cep, RW Com, V2610 Oph, V1387 Ori, AU Ser, and FT UMa. Our
spectroscopy revealed two quadruple systems, TZ Boo and V2610 Oph, while three
stars showing small photometric amplitudes, EL Boo, V1387 Ori, and FT UMa, were
found to be triple systems. GK Cep is close binary with a faint third
component.
  While most of the studied eclipsing systems are contact binaries, VZ CVn and
GK Cep are detached or semi-detached double-lined binaries, and EL Boo, V1387
Ori and FT UMa are close binaries of uncertain binary type. The large fraction
of triple and quadruple systems found in this sample supports the hypothesis of
formation of close binaries in multiple stellar systems; it also demonstrates
that low photometric amplitude binaries are a fertile ground for further
discoveries of multiple systems.


title:
Dynamics of strongly correlated ions in a partially ionized quantum
  plasma

abstract:
  A scheme which allows to compute the dynamics of strongly correlated
classical ions embedded into a partiallzy ionized quantum plasma by first
principles molecular dynamics is presented. The dynamically screened dust
approach of Joyce and Lampe [Phys. Rev. Lett. {\bf 88}, 095006 (2002] ist
generalized to quantum systems. The electrons are treated fully
quantum-mechanically taking into account their dynamical screening of the
ion-ion interaction in linear response on the basis of an extended Mermin
formula. The scheme allows to include the effect of the electron dynamics,
electron streaming, wake effects and electron magnetization.


title: Remarks on the GNS Representation and the Geometry of Quantum States

abstract:
  It is shown how to introduce a geometric description of the algebraic
approach to the non-relativistic quantum mechanics. It turns out that the GNS
representation provides not only symplectic but also Hermitian realization of a
`quantum Poisson algebra'. We discuss alternative Hamiltonian structures
emerging out of different GNS representations which provide a natural setting
for quantum bi-Hamiltonian systems.


title: Comments on Holographic Fermi Surfaces

abstract:
  Recently, a mechanism for the development of a fermi surface in a holographic
model of large N QCD with a baryon chemical potential was proposed. We examine
similar constructions to determine when this mechanism persists. We find a
class of models in which it does.


title: Higher order terms in an improved heterotic M theory

abstract:
  Curvature squared terms are added to a consistent formulation of supergravity
on manifolds with boundary which is meant to represent the low energy limit of
the strongly coupled heterotic string. These terms are necessary for the
cancellation of gravitational anomalies and for reduction to lower dimensions
with broken chiral symmetry. The consequences of anomaly cancellation when flux
and extrinsic curvature terms are taken into account have yet to be fully
exploited, but some implications for flux terms are discussed.


title: Line shape of the muH(3p - 1s) hyperfine transitions

abstract:
  The (3p - 1s) X-ray transition to the muonic hydrogen ground state was
measured with a high resolution crystal spectrometer. A Doppler effect
broadening of the X-ray line was established which could be attributed to
different Coulomb de-excitation steps preceding the measured transition. The
assumption of a statistical population of the hyperfine levels of the muonic
hydrogen ground state was directly confirmed by the experiment and measured
values for the hyperfine splitting can be reported. The results allow a
decisive test of advanced cascade model calculations and establish a method to
extract fundamental strong-interaction parameters from pionic hydrogen
experiments.


title:
Scattering a pulse from a chaotic cavity: Transitioning from algebraic
  to exponential decay

abstract:
  The ensemble averaged power scattered in and out of lossless chaotic cavities
decays as a power law in time for large times. In the case of a pulse with a
finite duration, the power scattered from a single realization of a cavity
closely tracks the power law ensemble decay initially, but eventually
transitions to an exponential decay. In this paper, we explore the nature of
this transition in the case of coupling to a single port. We find that for a
given pulse shape, the properties of the transition are universal if time is
properly normalized. We define the crossover time to be the time at which the
deviations from the mean of the reflected power in individual realizations
become comparable to the mean reflected power. We demonstrate numerically that,
for randomly chosen cavity realizations and given pulse shapes, the probability
distribution function of reflected power depends only on time, normalized to
this crossover time.


title: Dipole oscillations of confined lattice bosons in one dimension

abstract:
  We study the dynamics of a non-integrable system comprising interacting cold
bosons trapped in an optical lattice in one-dimension by means of exact
time-dependent numerical DMRG techniques. Particles are confined by a parabolic
potential, and dipole oscillations are induced by displacing the trap center of
a few lattice sites. Depending on the system parameters this motion can vary
from undamped to overdamped. We study the dipole oscillations as a function of
the lattice displacement, the particle density and the strength of
interparticle interactions. These results explain the recent experiment C.D.
Fertig et al., Phys. Rev. Lett. 94, 120403 (2005).


title: Inclusive semileptonic B decays: |V_{ub}| and |V_{cb}|

abstract:
  The present status of the measurement of the inclusive semileptonic $B$
decays is reviewed. In particular the determination of the
Cabibbo-Kobayashi-Maskawa matrix elements $|V_{cb}|$ and $|V_{ub}|$ is
discussed and some future prospects are given.


title: Maximal solutions for $-\Delta u+u^q=0$ in open or finely open sets

abstract:
  We study the existence and uniqueness of new classes of solutions of the
superlinear equation $-\Delta u+u^q=0$ (q>1) in a domain of R^N or in a finely
open set for the topology associated to the Bessel capacity C_{2,q'}. Condition
of existence or uniqueness of solutions with boundary blow-up are obtained
generalizing the results of Dhersin-Le Gall and of Labutin.


title:
Probing the radio to X-ray connection of the Vela X PWN with Fermi LAT
  and H.E.S.S

abstract:
  Morphologically it appears as if the Vela X PWN consists of two emission
regions: whereas X-ray (1 keV) and very high energy (VHE) H.E.S.S. gamma-ray
observations appear to define a cocoon type shape south of the pulsar, radio
observations reveal an extended area of size 2 deg by 3 deg (including the
cocoon area), also south of the Vela pulsar. Since no wide field of view (FoV)
observations of the synchrotron emission between radio and X-rays are
available, we do not know how the lepton (e+/-) spectra of these two components
connect and how the morphology changes with energy. Currently we find that two
distinct lepton spectra describe the respective radio and X-ray/VHE gamma-ray
spectra, with a field strength of 5 muG self-consistently describing a
radiation spectral break (or energy maximum) in the multi-TeV domain as
observed by H.E.S.S. (if interpreted as IC radiation), while predicting the
total hard X-ray flux above 20 keV (measured by the wide FoV INTEGRAL
instrument) within a factor of two. If this same field strength is also
representative of the radio structure (including filaments), the implied IC
component corresponding to the highest radio frequencies should reveal a
relatively bright high energy gamma-ray structure and Fermi LAT should be able
to resolve it. A higher field strength in the filaments would however imply
fewer leptons in Vela X and hence a fainter Fermi LAT signal.


title: Parton Distribution Amplitudes and Non-Perturbative Renormalisation

abstract:
  We present results for the first two moments of the light-cone distribution
amplitudes of the pion and kaon pseudo-scalar mesons and of the rho, K* and phi
vector mesons. The calculations are performed on the RBC/UKQCD collaborations'
ensembles generated with the Iwasaki gauge action and with 2+1 flavours of
domain wall fermions. In addition we also provide some results on the necessary
non-perturbative renormalisation which we perform using the Rome-Southampton
method. We discuss the benefits of the momentum source approach such as much
smaller statistical errors and the possibility to see effects of the
discretisation.


title: Random Chain Recurrent Sets for Random Dynamical Systems

abstract:
  It is known by the Conley's theorem that the chain recurrent set $CR(\phi)$
of a deterministic flow $\phi$ on a compact metric space is the complement of
the union of sets $B(A)-A$, where $A$ varies over the collection of attractors
and $B(A)$ is the basin of attraction of $A$. It has recently been shown that a
similar decomposition result holds for random dynamical systems on noncompact
separable complete metric spaces, but under a so-called \emph{absorbing
condition}. In the present paper, the authors introduce a notion of random
chain recurrent sets for random dynamical systems, and then prove the random
Conley's theorem on noncompact separable complete metric spaces \emph{without}
the absorbing condition.


title: Tuning the Josephson current in carbon nanotubes with the Kondo effect

abstract:
  We investigate the Josephson current in a single wall carbon nanotube
connected to superconducting electrodes. We focus on the parameter regime in
which transport is dominated by Kondo physics. A sizeable supercurrent is
observed for odd number of electrons on the nanotube when the Kondo temperature
Tk is sufficiently large compared to the superconducting gap. On the other hand
when, in the center of the Kondo ridge, Tk is slightly smaller than the
superconducting gap, the supercurrent is found to be extremely sensitive to the
gate voltage Vbg. Whereas it is largely suppressed at the center of the ridge,
it shows a sharp increase at a finite value of Vbg. This increase can be
attributed to a doublet-singlet transition of the spin state of the nanotube
island leading to a pi shift in the current phase relation. This transition is
very sensitive to the asymmetry of the contacts and is in good agreement with
theoretical predictions.


title:
Magnetic Phase Diagrams of Manganites-like Local-Moment Systems with
  Jahn-Teller distortions

abstract:
  We use an extended two-band Kondo lattice model (KLM) to investigate the
occurrence of different (anti-)ferromagnetic phases or phase separation
depending on several model parameters. With regard to CMR-materials like the
manganites we have added a Jahn-Teller term, direct antiferromagnetic coupling
and Coulomb interaction to the KLM. The electronic properties are
self-consistently calculated in an interpolating self-energy approach with no
restriction to classical spins and going beyond mean-field treatments. Further
on we do not have to limit the Hund's coupling to low or infinite values.
Zero-temperature phase diagrams are presented for large parameter intervals.
There are strong influences of the type of Coulomb interaction (intraband,
interband) and of the important parameters (Hund's coupling, direct
antiferromagnetic exchange, Jahn-Teller distortion), especially at intermediate
couplings.


title:
Topology of Fatou components for endomorphisms of CP^k: Linking with the
  Green's Current

abstract:
  Little is known about the global topology of the Fatou set $U(f)$ for
holomorphic endomorphisms $f: \mathbb{CP}^k \to \mathbb{CP}^k$, when $k >1$.
Classical theory describes $U(f)$ as the complement in $ \mathbb{CP}^k$ of the
support of a dynamically-defined closed positive $(1,1)$ current. Given any
closed positive $(1,1)$ current $S$ on $ \mathbb{CP}^k$, we give a definition
of linking number between closed loops in $\mathbb{CP}^k \setminus \supp S$ and
the current $S$. It has the property that if $lk(\gamma,S) \neq 0$, then
$\gamma$ represents a non-trivial homology element in $H_1(\mathbb{CP}^k
\setminus \supp S)$.
  As an application, we use these linking numbers to establish that many
classes of endomorphisms of $\mathbb{CP}^2$ have Fatou components with
infinitely generated first homology. For example, we prove that the Fatou set
has infinitely generated first homology for any polynomial endomorphism of
$\mathbb{CP}^2$ for which the restriction to the line at infinity is hyperbolic
and has disconnected Julia set. In addition we show that a polynomial skew
product of $\mathbb{CP}^2$ has Fatou set with infinitely generated first
homology if some vertical Julia set is disconnected. We then conclude with a
section of concrete examples and questions for further study.


title: f-categories and Tate motives

abstract:
  Using Beilinson's theory of f-categories, we prove that the triangulated
category of Tate motives over a field k is equivalent to the bounded derived
category of its heart, provided that k is algebraic over the rationals. This
answers a question asked by Levine.


title: Linear perturbations of quaternionic metrics

abstract:
  We extend the twistor methods developed in our earlier work on linear
deformations of hyperkahler manifolds [arXiv:0806.4620] to the case of
quaternionic-Kahler manifolds. Via Swann's construction, deformations of a
4d-dimensional quaternionic-Kahler manifold $M$ are in one-to-one
correspondence with deformations of its $4d+4$-dimensional hyperkahler cone
$S$. The latter can be encoded in variations of the complex symplectomorphisms
which relate different locally flat patches of the twistor space $Z_S$, with a
suitable homogeneity condition that ensures that the hyperkahler cone property
is preserved. Equivalently, we show that the deformations of $M$ can be encoded
in variations of the complex contact transformations which relate different
locally flat patches of the twistor space $Z_M$ of $M$, by-passing the Swann
bundle and its twistor space. We specialize these general results to the case
of quaternionic-Kahler metrics with $d+1$ commuting isometries, obtainable by
the Legendre transform method, and linear deformations thereof. We illustrate
our methods for the hypermultiplet moduli space in string theory
compactifications at tree- and one-loop level.


title:
AGILE detection of intense gamma-ray emission from the blazar PKS
  1510-089

abstract:
  We report the detection by the AGILE (Astro-rivelatore Gamma a Immagini
LEggero) satellite of an intense gamma-ray flare from the source AGL
J1511-0909, associated with the powerful quasar PKS 1510-089, during ten days
of observations from 23 August to 1 September 2007. During the observation
period, the source was in optical decrease following a flaring event monitored
by the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope
(WEBT). The simultaneous gamma-ray, optical, and radio coverage allows us to
study the spectral energy distribution and the theoretical models based on the
synchrotron and inverse Compton (IC) emission mechanisms. AGILE observed the
source with its two co-aligned imagers, the Gamma-Ray Imaging Detector and the
hard X-ray imager Super-AGILE sensitive in the 30 MeV - 50 GeV and 18 - 60 keV
bands, respectively. Between 23 and 27 August 2007, AGILE detected gamma-ray
emission from PKS 1510-089 when this source was located about 50 degrees
off-axis, with an average flux of (270 +/- 65) x 10^{-8} photons cm^{-2} s^{-1}
for photon energy above 100 MeV. In the following period, 28 August - 1
September, after a satellite re-pointing, AGILE detected the source at about 35
degrees off-axis, with an average flux (E > 100 MeV) of (195 +/- 30) x 10^{-8}
photons cm^{-2} s^{-1}. No emission was detected by Super-AGILE, with a 3-sigma
upper limit of 45 mCrab in 200 ksec. The spectral energy distribution is
modelled with a homogeneous one-zone synchrotron self Compton (SSC) emission
plus contributions by external photons: the SSC emission contributes primarily
to the X-ray band, whereas the contribution of the IC from the external disc
and the broad line region match the hard gamma-ray spectrum observed.


title:
Ample divisors on moduli spaces of weighted pointed rational curves,
  with applications to log MMP for $\bar{M}_{0,n}$

abstract:
  We introduce a new technique for proving positivity of certain divisor
classes on $\bar{M}_{0,n}$ and its weighted variants. Our methods give an
unconditional description of the spaces of symmetric weighted pointed rational
curves as log canonical models of $\bar{M}_{0,n}$.


title: Finite Chevalley groups and loop groups

abstract:
  Let p, ell be distinct primes and let q be a power of p. Let G be a connected
compact Lie group. We show that there exists an integer b such that the mod ell
cohomology of the classifying space of a finite Chevalley group G(F_q) is
isomorphic to the mod ell cohomology of the classifying space of the loop group
LG for q=p^{ab}, a>0.


title:
Searching optimal shape in viscous flow: its dependence on Reynolds
  number

abstract:
  In this work a simple problem on 2D optimal shape for body immersed in a
viscous flow is analyzed. The body has geometrical constraints and its profile
would be found in the class of cubics which satisfy those conditions. The
optimal profile depends on the leading coefficient of these cubics and its
relation with the Reynolds number of the system is found. The solution to the
problem uses a method based on a suitable transformation rule for the cartesian
reference.


title: Velocity dominated singularities in the cheese slice universe

abstract:
  We investigate the properties of spacetimes resulting from matching together
exact solutions using the Darmois matching conditions. In particular we focus
on the asymptotically velocity term dominated property (AVTD). We propose a
criterion that can be used to test if a spacetime constructed from a matching
can be considered AVTD. Using the Cheese Slice universe as an example, we show
that a spacetime constructed from a such a matching can inherit the AVTD
property from the original spacetimes. Furthermore the singularity resulting
from this particular matching is an AVTD singularity.


title: Structure and Formation of Elliptical and Spheroidal Galaxies

abstract:
  New surface photometry of all known elliptical galaxies in the Virgo cluster
is added to published data to derive composite profiles over large dynamic
ranges. Sersic functions fit them remarkably well. Effective brightnesses and
radii are derived via Sersic fits and by integrating the profiles
nonparametrically. We strongly confirm two dichotomies: (1) Elliptical galaxies
from cDs to M32 form a tight sequence in Fundamental Plane parameter space that
is almost perpendicular to the sequence of spheroidal galaxies from NGC 205 to
Draco. This is consistent with our understanding of their different formation
processes: mergers for Es and conversion of late-type galaxies into spheroidals
by environmental effects and by energy feedback from supernovae. (2)
Ellipticals come in two varieties: e.g., our 10 brightest Es have cuspy cores;
our 17 fainter Es do not have cores. We find a new distinct component in
coreless Es. All have extra light at the center above the inward extrapolation
of the outer Sersic profile. We suggest that extra light is made by starbursts
in dissipational (wet) mergers, as in numerical simulations. Three other new
aspects also point to an explanation of how the E-E dichotomy formed: extra
light Es were made in wet mergers while core Es were made in dry mergers. We
confirm that core Es do and extra light Es generally do not contain X-ray gas.
This suggests why the E-E dichotomy arose. Only core Es and their progenitors
are massive enough to retain hot gas that can make dry mergers dry and protect
old star populations from late star formation.


title: Simulation of neutrons produced by high-energy muons underground

abstract:
  This article describes the Monte Carlo simulation used to interpret the
measurement of the muon-induced neutron flux in the Boulby Underground
Laboratory (North Yorkshire, UK), recently performed using a large scintillator
veto deployed around the ZEPLIN-II WIMP detector. Version 8.2 of the GEANT4
toolkit was used after relevant benchmarking and validation of neutron
production models. In the direct comparison between Monte Carlo and
experimental data, we find that the simulation produces a 1.8 times higher
neutron rate, which we interpret as over-production in lead by GEANT4. The
dominance of this material in neutron production allows us to estimate the
absolute neutron yield in lead as (1.31 +/- 0.06) x 10^(-3)
neutrons/muon/(g/cm^2) for a mean muon energy of 260 GeV. Simulated nuclear
recoils due to muon-induced neutrons in the ZEPLIN-II target volume (~1 year
exposure) showed that, although a small rate of events is expected from this
source of background in the energy range of interest for dark matter searches,
no event survives an anti-coincidence cut with the veto.


title:
Exciton Dynamics on Rubrene (001) Crystal Surfaces with Microstructure
  Confinement

abstract:
  The exciton dynamics on flat (001) rubrene crystal surfaces have been
compared with those under confined pyramidal geometry by time-resolved
photoluminescence with micrometer spatial resolution. The luminescence spectra
can be interpreted in terms of generation of a free and a self-trapped exciton.
Their ratio depends significantly on the structural size which we explain by
the optical absorption profile of the pyramids in combination with the exciton
diffusion constant. For the latter a lower limit of 0.2 cm2/s at 4 K has been
estimated. Temperature-dependent decay times reveal activation barriers between
free and self-trapped exciton of 3 meV and 14 meV.


title: Lorentz invariance, vacuum energy, and cosmology

abstract:
  This contribution reviews recent work on a new approach to the cosmological
constant problem, which starts from the macroscopic behavior of a conserved
relativistic microscopic variable q. First, the statics of the vacuum energy
density is discussed and, then, the dynamics in a cosmological context.


title: Spectral variability in Cygnus X-3

abstract:
  We model the broad-band X-ray spectrum of Cyg X-3 in all states displayed by
this source as observed by the Rossi X-ray Timing Explorer. From our models, we
derive for the first time unabsorbed spectral shapes and luminosities for the
full range of spectral states. We interpret the unabsorbed spectra in terms of
Comptonization by a hybrid electron distribution and strong Compton reflection.
We study the spectral evolution and compare with other black hole as well as
neutron star sources. We show that a neutron star accretor is not consistent
with the spectral evolution as a function of Ledd and especially not with the
transition to a hard state. Our results point to the compact object in Cyg X-3
being a massive, ~30 Msun black hole.


title: Gravitational collapse of radiation fluid in higher dimensions

abstract:
  We examine the problem of the gravitational collapse using higher dimensional
Husain spacetime for the null fluid. The equations of state chosen to solve the
field equations contain linear, quadratic and arbitrary powers of the radial
parameter. The resulting mass evolution is discussed for each case.


title:
The properties of brown dwarfs and low-mass hydrogen-burning stars
  formed by disc fragmentation

abstract:
  We suggest that a high proportion of brown dwarfs are formed by gravitational
fragmentation of massive extended discs around Sun-like stars. Such discs
should arise frequently, but should be observed infrequently, precisely because
they fragment rapidly. By performing an ensemble of radiation-hydrodynamic
simulations, we show that such discs fragment within a few thousand years, and
produce mainlybrown dwarf (BDs) stars, but also planetary mass (PM) stars and
very low-mass hydrogen-burning (HB) stars. Most of the the PM stars and BDs are
ejected by mutual interactions. We analyse the statistical properties of these
stars, and compare them with observations. After a few hundred thousand years
the Sun-like primary is typically left with a close low-mass HB companion, and
two much wider companions: a low-mass HB star and a BD star, or a BD-BD binary.
There is a BD desert extending out to at least ~100 AU; this is because BDs
tend to be formed further out than low-mass HB stars, and then they tend to be
scattered even further out, or even into the field. BDs form with discs of a
few Mj and radii of a few tens of AU, and they are more likely to retain these
discs if they remain bound to the primary star. Binaries form by pairing of the
newly-formed stars in the disc, giving a low-mass binary fraction of ~0.16.
These binaries include close and wide BD/BD binaries and BD/PM binaries. BDs
that remain as companions to Sun-like stars are more likely to be in BD/BD
binaries than are BDs ejected into the field. Disc fragmentation is a robust
mechanism; even if only a small fraction of Sun-like stars host the required
massive extended discs,this mechanism can produce all the PM stars observed,
most of the BD stars, and a significant proportion of the very low-mass HB
stars.


title: On a theorem of Faltings on formal functions

abstract:
  In 1980, Faltings proved, by deep local algebra methods, a local result
regarding formal functions which has the following global geometric fact as a
consequence.
  Theorem: Let k be an algebraically closed field (of any characteristic). Let
Y be a closed subvariety of a projective irreducible variety X defined over k.
Assume that X \subseteq P^n, dim(X)=d>2 and Y is the intersection of X with r
hyperplanes of P^n, with r \le d-1. Then, every formal rational function on X
along Y can be (uniquely) extended to a rational function on X.
  Due to its importance, the aim of this paper is to provide two elementary
global geometric proofs of this theorem.


title:
Experimental demonstration of a mu=-1 metamaterial lens for magnetic
  resonance imaging

abstract:
  In this work a mu=-1 metamaterial (MM) lens for magnetic resonance imaging
(MRI) is demonstrated. MRI uses surface coils to detect the radiofrequency(RF)
energy absorbed and emitted by the nuclear spins in the imaged object. The
proposed MM lens manipulates the RF field detected by these surface coils, so
that the coil sensitivity and spatial localization is substantially improved.
Beyond this specific application, we feel that the reported results are the
experimental confirmation of a new concept for the manipulation of RF field in
MRI, which paves the way to many other interesting applications.


title: Ultrashort pulse propagation and the Anderson localization

abstract:
  We investigate the dynamics of a 10 fs light pulse propagating in a random
medium by the direct solution of the 3D Maxwell equations. Our approach employs
molecular dynamics to generate a distribution of spherical scatterers and a
parallel finite-difference time-domain code for the vectorial wave propagation.
We calculate the disorder-averaged energy velocity and the decay time of the
transmitted pulse Versus the localization length for an increasing refractive
index.


title: Kummer generators and lambda invariants

abstract:
  Let $F_0=\mathbf Q(\sqrt{-d})$ be an imaginary quadratic field with $3\nmid
d$ and let $K_0=\mathbf Q(\sqrt{3d})$. Let $\varepsilon_0$ be the fundamental
unit of $K_0$ and let $\lambda$ be the Iwasawa $\lambda$-invariant for the
cyclotomic $\mathbf Z_3$-extension of $F_0$. The theory of 3-adic $L$-functions
gives conditions for $\lambda\ge 2$ in terms of $\epsilon_0$ and the class
numbers of $F_0$ and $K_0$. We construct units of $K_1$, the first level of the
$\mathbf Z_3$-extension of $K_0$, that potentially occur as Kummer generators
of unramified extensions of $F_1(\zeta_3)$ and which give an algebraic
interpretation of the condition that $\lambda\ge 2$. We also discuss similar
results on $\lambda\ge 2$ that arise from work of Gross-Koblitz.


title:
Density-functional investigation of the rhombohedral to simple cubic
  phase transition of arsenic

abstract:
  We report on our investigation of the crystal structure of arsenic under
compression, focusing primarily on the pressure-induced A7 to simple cubic (sc)
phase transition. The two-atom rhombohedral unit cell is subjected to pressures
ranging from 0 GPa to 200 GPa; for each given pressure, cell lengths and
angles, as well as atomic positions, are allowed to vary until the fully
relaxed structure is obtained. We find that the nearest and next-nearest
neighbor distances give the clearest indication of the occurrence of a
structural phase transition. Calculations are performed using the local density
approximation (LDA) and the PBE and PW91 generalized gradient approximations
(GGA-PBE and GGA-PW91) for the exchange-correlation functional. The A7 to sc
transition is found to occur at 21+/-1 GPa in the LDA, at 28+/-1 GPa in the
GGA-PBE and at 29+/-1 GPa in the GGA-PW91; no volume discontinuity is observed
across the transition in any of the three cases. We use k-point grids as dense
as 66X66X66 to enable us to present reliably converged results for the A7 to sc
transition of arsenic.


title:
Treatment of a semi-metal to metal structural phase transition:
  convergence properties of the A7 to sc transition of arsenic

abstract:
  The material presented here is supplementary to the article entitled:
"Density-functional investigation of the rhombohedral to simple cubic phase
transition of arsenic"; it deals with the convergence issues involved in
studying a semi-metal to metal structural phase transition such as the A7 to sc
transition of arsenic.


title: Operator splittings and spatial approximations for evolution equations

abstract:
  The convergence of various operator splitting procedures, such as the
sequential, the Strang and the weighted splitting, is investigated in the
presence of a spatial approximation. To this end a variant of Chernoff's
product formula is proved. The methods are applied to abstract partial delay
differential equations.


title:
Noise influence on electron dynamics in semiconductors driven by a
  periodic electric field

abstract:
  Studies about the constructive aspects of noise and fluctuations in different
non-linear systems have shown that the addition of external noise to systems
with an intrinsic noise may result in a less noisy response. Recently, the
possibility to reduce the diffusion noise in semiconductor bulk materials by
adding a random fluctuating contribution to the driving static electric field
has been tested. The present work extends the previous theories by considering
the noise-induced effects on the electron transport dynamics in low-doped
n-type GaAs samples driven by a high-frequency periodic electric field
(cyclostationary conditions). By means of Monte Carlo simulations, we calculate
the changes in the spectral density of the electron velocity fluctuations
caused by the addition of an external correlated noise source. The results
reported in this paper confirm that, under specific conditions, the presence of
a fluctuating component added to an oscillating electric field can reduce the
total noise power. Furthermore, we find a nonlinear behaviour of the spectral
density with the noise intensity. Our study reveals that, critically depending
on the external noise correlation time, the dynamical response of electrons
driven by a periodic electric field receives a benefit by the constructive
interplay between the fluctuating field and the intrinsic noise of the system.


title: Low-frequency solar p modes as seen by GOLF and GONG instruments

abstract:
  In the case of spatially-revolved helioseismic data (such as MDI, GONG, HMI),
the usual mode-fitting analysis consists of fitting the 2l+1 individual
m-spectra of a given multiplet (n, l) either individually or simultaneously.
Such fitting methods fail to obtain reliable estimates of the mode parameters
(frequency, splitting, ...) when the signal-to-noise ratio (SNR) is low, which
makes those methods not suitable when one wants to look at the low-amplitude,
long-lived solar p modes in the low-frequency range. Instead, Salabert et al.
(2007) developed a new method to extract the mode parameters by adjusting the
rotation- and structure-induced frequency shift for each m-spectrum to minimize
the mode width in the m-averaged spectrum (a "collapsogram"). The m-averaged
spectrum technique, applied to the spatially-resolved GONG and MDI data,
appeared to be a powerful tool for low SNR modes in the low-frequency range.
Another possibility to increase the SNR is to combine data from different
instruments (Garcia et al. 2004a). We present here an adaptation of both
techniques: the "collapsograms" applied to a combination of observations from a
Sun-as-a-star instrument, GOLF, and a disk-imaged one, GONG.


title: On the cable expansion formula

abstract:
  In this paper, a generalized version of Morton's formula is proved. Using
this formula, one can write down the colored Jones polynomials of cabling of an
knot in terms of the colored Jones polynomials of the original knot.


title: High pT and jet physics from RHIC to LHC

abstract:
  The observation of the strong suppression of high pT hadrons in heavy ion
collisions at the Relativistic Heavy Ion Collider (RHIC) at BNL has motivated a
large experimental program using hard probes to characterize the deconfined
medium created. However what can be denoted as ``leading particle physics''
accessible at RHIC presents some limitations which motivate at higher energy
the study of much more penetrating objects: jets. The gain in center of mass
energy expected at the Large Hadron Collider (LHC) at CERN will definitively
improve our understanding on how the energy is lost in the system opening a new
major window of study: the physics of jets on an event-by-event basis. We will
concentrate on the expected performance for jet reconstruction in ALICE using
the EMCal calorimeter.


title: Noise driven translocation of short polymers in crowded solutions

abstract:
  In this work we study the noise induced effects on the dynamics of short
polymers crossing a potential barrier, in the presence of a metastable state.
An improved version of the Rouse model for a flexible polymer has been adopted
to mimic the molecular dynamics by taking into account both the interactions
between adjacent monomers and introducing a Lennard-Jones potential between all
beads. A bending recoil torque has also been included in our model. The polymer
dynamics is simulated in a two-dimensional domain by numerically solving the
Langevin equations of motion with a Gaussian uncorrelated noise. We find a
nonmonotonic behaviour of the mean first passage time and the most probable
translocation time, of the polymer centre of inertia, as a function of the
polymer length at low noise intensity. We show how thermal fluctuations
influence the motion of short polymers, by inducing two different regimes of
translocation in the molecule transport dynamics. In this context, the role
played by the length of the molecule in the translocation time is investigated.


title: Higher Asymptotics of Laplace's Approximation

abstract:
  We present expressions for the coefficients which arise in asymptotic
expansions of multiple integrals of Laplace type (the first term of which is
known as Laplace's approximation) in terms of asymptotic series of the
functions in the integrand. Our most general result assumes no smoothness of
the functions of the integrand, but the expressions we obtain contain integrals
which may be difficult to evaluate in practice. We then make additional
assumptions which are sufficient to simplify these integrals, in some cases
obtaining explicit formulae for the coefficients in the asymptotic expansions.


title: CNONa and 12C/13C in giants of 10 open clusters

abstract:
  Evolved low-mass stars of a wide range of metallicity bear signatures of a
non-standard mixing event in their surface abundances of Li, C, and N, and in
their 12C/13C ratio. A Na overabundance has also been reported in some giants
of open clusters but remains controversial. The cause of the extra-mixing has
been attributed to thermohaline convection that should take place after the RGB
bump for low-mass stars and on the early-AGB for more massive objects. To track
the occurrence of this process over a wide mass range, we derive in a
homogeneous way the abundances of C, N, O, and Na, as well as the 12C/13C ratio
in a sample of 31 giants of 10 open clusters with turn-off masses from 1.7 to
3.1 Msun. A group of first ascent red giants with M/Msun \leq 2.5 exhibits
lower [N/C] ratios than those measured in clump giants of the same mass range,
suggesting an additional increase in the [N/C] ratio after the first dredge-up.
The sodium abundances corrected from NLTE are found to be about solar. [Na/Fe]
shows a slight increase of 0.10 dex as a function of stellar mass in the 1.8 to
3.2 Msun range covered by our sample, in agreement with standard first
dredge-up predictions. Our results do not support previous claims of sodium
overabundances as high as +0.60 dex. An anti-correlation between 12C/13C and
turn-off mass is identified and interpreted as being caused by a post-bump
thermohaline mixing. Moreover, we find low 12C/13C ratios in a few
intermediate-mass early-AGB stars, confirming that an extra-mixing process also
operates in stars that do not experienced the RGB bump. In this case, the
extra-mixing possibly acts on the early-AGB, in agreement with theoretical
expectations for thermohaline mixing. [abridged]


title:
Dead Waters: Large amplitude interfacial waves generated by a boat in a
  stratified fluid

abstract:
  We present fluid dynamics videos of the motion of a boat on a two-layer or
three-layer fluid. Under certain specific conditions, this setup generates
large amplitude interfacial waves, while no surface waves are visible. The boat
is slowed down leading to a peristaltic effect and sometimes even stopped: this
is the so-called dead water phenomenon.


title:
Strong signatures of radiation reaction below the radiation dominated
  regime

abstract:
  The influence of radiation reaction (RR) on multiphoton Thomson scattering by
an electron colliding head-on with a strong laser beam is investigated in a new
regime, in which the momentum transferred on average to the electron by the
laser pulse approximately compensates the one initially prepared. This
equilibrium is shown to be far more sensitive to the influence of RR than
previously studied scenarios. As a consequence RR can be experimentally
investigated with currently available laser systems and the underlying widely
discussed theoretical equations become testable for the first time.


title:
DC and AC Josephson effects with superfluid Fermi atoms across a
  Feshbach resonance

abstract:
  We show that both DC and AC Josephson effects with superfluid Fermi atoms in
the BCS-BEC crossover can be described at zero temperature by a nonlinear
Schrodinger equation (NLSE). By comparing our NLSE with mean-field extended BCS
calculations, we find that the NLSE is reliable in the BEC side of the
crossover up to the unitarity limit. The NLSE can be used for weakly-linked
atomic superfluids also in the BCS side of the crossover by taking the
tunneling energy as a phenomenological parameter.


title: OPED reconstruction algorithm for limited angle problem

abstract:
  The structure of the reconstruction algorithm OPED permits a natural way to
generate additional data, while still preserving the essential feature of the
algorithm. This provides a method for image reconstruction for limited angel
problems. In stead of completing the set of data, the set of discrete sine
transforms of the data is completed. This is achieved by solving systems of
linear equations that have, upon choosing appropriate parameters, positive
definite coefficient matrices. Numerical examples are presented.


title: On the solar origin of the 220.7 signal

abstract:
  Gravity modes in the Sun have been long searched during the past decades.
Using their asymptotic properties Garcia et al. (2007) found the signature of
the dipole g modes analyzing an spectral window between 25 and 140 muHz of
velocity power spectrum obtained from the GOLF/SoHO instrument. Using this
result it has been possible to check some properties of the structure of the
solar interior (Garcia, Mathur & Ballot 2008) as well as some indications on
the dynamics of the core. However, the individual detection of such modes
remains evasive and they are needed to really improve our knowledge of the
deepest layers in the Sun (Mathur et al. 2008). In this work we study the
signal at 220.7 muHz which is present in most of the helioseismic instruments
during the last 10 years. This signal has been previously identified as part of
a g-mode candidate in the GOLF data (Turck-Chieze et al. 2004; Mathur et al.
2007) and in SPM/VIRGO (Garcia et al. 2008) with more than 90% confidence
level. It could be labelled as the l=2 n=-3 g mode as it is in the region were
this mode is expected.
  We have checked the possibility that the 220.7 muHz signal could have an
instrumental origin without success by analysing all the available housekeeping
data as well as the information on the roll, pith and yaw of the SoHO
spacecraft. In consequence, we are confident that this signal has a solar
origin.


title:
A strictly stationary, N-tuplewise independent counterexample to the
  central limit theorem

abstract:
  For an arbitrary integer N that is at least 2, this paper gives a
construction of a strictly stationary, N-tuplewise independent sequence of
(non-degenerate) bounded random variables such that the Central Limit Theorem
fails to hold. The sequence is in part an adaptation of a non-stationary
example with similar properties constructed by one of the authors (ARP) in a
paper published in 1998.


title: Pion-Kaon interaction effects on CP violation in B -> K pi+ pi- decays

abstract:
  We apply QCD factorization to the quasi two-body B ->(K pi) pi decays where
the (K pi)-pair effective mass is limited to 1.8 GeV. Our strong interaction
phases constrained by theory and pi-K experimental data yield useful
information for studies of CP violation


title:
Characterization of AGN and their hosts in the Extended Groth Strip: a
  multiwavelength analysis

abstract:
  We have employed a reliable technique of classification of Active Galactic
Nuclei (AGN) based on the fit of well-sampled spectral energy distributions
(SEDs) with a complete set of AGN and starburst galaxy templates. We have
compiled ultraviolet, optical, and infrared data for a sample of 116 AGN
originally selected for their X-ray and mid-infrared emissions (96 with single
detections and 20 with double optical counterparts). This is the most complete
compilation of multiwavelength data for such a big sample of AGN in the
Extended Groth Strip (EGS). Through these SEDs, we are able to obtain highly
reliable photometric redshifts and to distinguish between pure and
host-dominated AGN. For the objects with unique detection we find that they can
be separated into five main groups, namely: Starburst-dominated AGN (24 % of
the sample), Starburst-contaminated AGN (7 %), Type-1 AGN (21 %), Type-2 AGN
(24 %), and Normal galaxy hosting AGN (24 %). We find these groups concentrated
at different redshifts: Type-2 AGN and Normal galaxy hosting AGN are
concentrated at low redshifts, whereas Starburst-dominated AGN and Type-1 AGN
show a larger span. Correlations between hard/soft X-ray and ultraviolet,
optical and infrared luminosities, respectively, are reported for the first
time for such a sample of AGN spanning a wide range of redshifts. For the 20
objects with double detection the percentage of Starburst-dominated AGN
increases up to 48%.


title: A Planet in a 0.6-AU Orbit Around the K0 Giant HD 102272

abstract:
  We report the discovery of one or more planet-mass companions to the K0-giant
HD 102272 with the Hobby-Eberly Telescope. In the absence of any correlation of
the observed periodicities with the standard indicators of stellar activity,
the observed radial velocity variations are most plausibly explained in terms
of a Keplerian motion of at least one planet-mass body around the star. With
the estimated stellar mass of 1.9M$_\odot$, the minimum mass of the confirmed
planet is 5.9M$_J$. The planet's orbit is characterized by a small but nonzero
eccentricity of $e$=0.05 and the semi-major axis of 0.61 AU, which makes it the
most compact one discovered so far around GK-giants. This detection adds to the
existing evidence that, as predicted by theory, the minimum size of planetary
orbits around intermediate-mass giants is affected by both planet formation
processes and stellar evolution. The currently available evidence for another
planet around HD 102272 is insufficient to obtain an unambiguous two-orbit
solution.


title: Nonlinear bending of molecular films by polarized light

abstract:
  A theory of photoinduced directed bending of non-crystalline molecular films
is presented. Our approach is based on elastic deformation of the film due to
interaction between molecules ordered through polarized light irradiation. The
shape of illuminated film is obtained in the frame of the nonlinear elasticity
theory. It is shown that the shape and the curvature of the film depend on the
polarization and intensity of the light. The curvature of an irradiated film is
a non-monotonic function of the extinction coefficient.


title:
IRAM-PdBI Observations of Binary Protostars I: The Hierarchical System
  SVS13 in NGC1333

abstract:
  We present millimeter interferometric observations of the young stellar
object SVS13 in NCG1333 in the N2H+(1-0) line and at 1.4 and 3mm dust
continuum, using the IRAM Plateau de Bure interferometer. The results are
complemented by infrared data from the Spitzer Space Telescope. The millimeter
dust continuum images resolve four sources (A, B, C, and VLA3) in SVS13. With
the dust continuum images, we derive gas masses of 0.2-1.1 M_sun for the
sources. N2H+(1-0) line emission is detected and spatially associated with the
dust continuum sources B and VLA3. The observed mean line width is ~0.48 km/s
and the estimated virial mass is ~0.7 M_sun. By simultaneously fitting the
seven hyperfine line components of N2H+, we derive the velocity field and find
a symmetric velocity gradient of about 28 km/s/pc across sources B and VLA3,
which could be explained by core rotation. The velocity field suggests that
sources B and VLA3 are forming a physically bound protobinary system embedded
in a common N2H+ core. Spitzer images show mid-infrared emission from sources A
and C, which is spatially associated with the mm dust continuum emission. No
infrared emission is detected from source B, implying that the source is deeply
embedded. Based on the morphologies and velocity structure, we propose a
hierarchical fragmentation picture for SVS13 where the three sources (A, B, and
C) were formed by initial fragmentation of a filamentary prestellar core, while
the protobinary system (sources B and VLA3) was formed by rotational
fragmentation of a single collapsing sub-core.


title:
Pair vs many-body potentials: influence on elastic and plastic behavior
  in nanoindentation

abstract:
  Molecular-dynamics simulation can give atomistic information on the processes
occurring in nanoindentation experiments. In particular, the nucleation of
dislocation loops, their growth, interaction and motion can be studied. We
investigate how realistic the interatomic potentials underlying the simulations
have to be in order to describe these complex processes. Specifically we
investigate nanoindentation into a Cu single crystal. We compare simulations
based on a realistic many-body interaction potential of the
embedded-atom-method type with two simple pair potentials, a Lennard-Jones and
a Morse potential. We find that qualitatively many aspects of nanoindentation
are fairly well reproduced by the simple pair potentials: elastic regime,
critical stress and indentation depth for yielding, dependence on the crystal
orientation, and even the level of the hardness. The quantitative deficits of
the pair potential predictions can be traced back (i) to the fact that the pair
potentials are unable in principle to model the elastic anisotropy of cubic
crystals; (ii) as the major drawback of pair potentials we identify the gross
underestimation of the stable stacking fault energy. As a consequence these
potentials predict the formation of too large dislocation loops, the too rapid
expansion of partials, too little cross slip and in consequence a severe
overestimation of work hardening.


title: Self-energy and vertex radiative corrections in LQG

abstract:
  We consider the elementary radiative-correction terms in loop quantum
gravity. These are a two-vertex "elementary bubble" and a five-vertex "ball";
they correspond to the one-loop self-energy and the one-loop vertex correction
of ordinary quantum field theory. We compute their naive degree of (infrared)
divergence.


title:
On the Number of Rational Iterated Pre-images of the Origin Under
  Quadratic Dynamical Systems

abstract:
  For a quadratic endomorphism of the affine line defined over the rationals,
we consider the problem of bounding the number of rational points that
eventually land at the origin after iteration. In the article ``Uniform Bounds
on Pre-Images Under Quadratic Dynamical Systems,'' by two of the present
authors and five others, it was shown that the number of rational iterated
pre-images of the origin is bounded as one varies the morphism in a certain
one-dimensional family. Subject to the validity of the Birch and
Swinnerton-Dyer conjecture and some other related conjectures for the L-series
of a specific abelian variety and using a number of modern tools for locating
rational points on high genus curves, we show that the maximum number of
rational iterated pre-images is six. We also provide further insight into the
geometry of the ``pre-image curves.''


title:
Muon-spin rotation study of the in-plane magnetic penetration depth of
  FeSe_0.85: evidence for nodeless superconductivity

abstract:
  The in-plane magnetic penetration depth \lambda_{ab} of the iron selenide
superconductor with the nominal composition FeSe_0.85 was studied by means of
muon-spin rotation. The measurements of \lambda_{ab}^{-2}(T) are inconsistent
with the presence of nodes in the gap as well as with a simple isotropic s-wave
type of the order parameter, but can be equally well described within a two-gap
(s+s) and an anisotropic s-wave gap picture. This implies that the
superconducting energy gap in FeSe_0.85 contains no nodes.


title:
Spatial Cross Spectrum: Reducing Incoherent Convective Background of
  Resolved Heloseismic Instruments

abstract:
  Measurements of low-order p modes and gravity modes are perturbed by the
solar convective background. Such perturbation increases below 2mHz for
intensity measurements and 1mHz for velocity measurements. While the low-degree
modes have large spatial scales, the convective motions have much smaller
spatial distribution. In this work, we take advantage of these different scale
sizes to explore the use of spatial cross spectrum between different regions of
the Sun. The aim is to reduce the incoherent background noise and, therefore,
increase the signal-to-noise ratio of the signals that are coherent across the
full disk. To do so we use the VIRGO/LOI instrument aboard SoHO and the GONG
ground-based network to study the intensity and velocity spatial cross spectra.


title: Random sampling of long-memory stationary processe

abstract:
  This paper investigates the second order properties of a stationary process
after random sampling. While a short memory process gives always rise to a
short memory one, we prove that long-memory can disappear when the sampling law
has heavy enough tails. We prove that under rather general conditions the
existence of the spectral density is preserved by random sampling. We also
investigate the effects of deterministic sampling on seasonal long-memory.


title: The physics of eight flavours

abstract:
  When the flavour content of QCD is increased sufficiently, the theory
develops a non-trivial infra red fixed point. Thus, for a number of flavours
above a certain critical value, but not yet so high that asymptotic freedom is
lost, QCD becomes a conformal field theory. The location of the lower limit of
this conformal window has not yet been unequivocally determined. Using an
improved lattice action, and exploiting modern algorithms allowing for larger
lattices and lower quark masses, we have shown that the theory of QCD with
eight flavours breaks chiral symmetry in the continuum. We present proof that
the accompanying transition is thermal in nature and as a consequence, the
conformal window of QCD can only start afterwards, corroborating recent
analytical studies at the expense of older results.


title: Momentum-space interferometry with trapped ultracold atoms

abstract:
  Quantum interferometers are generally set so that phase differences between
paths in coordinate space combine constructive or destructively. Indeed, the
interfering paths can also meet in momentum space leading to momentum-space
fringes. We propose and analyze a method to produce interference in momentum
space by phase-imprinting part of a trapped atomic cloud with a detuned laser.
For one-particle wave functions analytical expressions are found for the fringe
width and shift versus the phase imprinted. The effects of unsharpness or
displacement of the phase jump are also studied, as well as many-body effects
to determine the potential applicability of momentum-space interferometry.


title: Simulation Monte-Carlo du Mod\`ele de Hubbard \`a deux dimensions

abstract:
  The Quantum Monte-Carlo simulations of the two-dimensional Hubbard model are
presented for the half filling. The method based on the direct-space proposed
by Suzuki and al., and Hirsch and al. was used. The states generated by this
method are basis states in occupation number representation built with Wannier
states localised on each site of the square array. The configurations of
fermions can be observed on the real 2D array. An antiferromagnetic factor is
defined and calculated for each temperature. The curves of energy, specific
heat, conducivity and antiferromagnetic factor are presented for different
values of the repulsive coulombian on site interaction U. There is a
metal-insulator transition at low temperature for small values of U. This
transition corresponds with a paramagnetic-ferromagnetic first order
transition. Indeed, for these interaction values, the energy curves show a gap
which is a characteristic of a first order transition. An hysteresis phenomenon
appears on the conductivity curves. There is a behaviour change for U/t=3.5.
For the values U>3.5 there is ferromagnetic-paramagnetic change without
observable effect on the energy and the specific heat. The metal-insulator
transition does not exist any more, the conductivity stays very small.
Isotherms of the physical quantities versus U/t show a transition which seems
to be the metal-insulator Mott transition. These results allow to draw a phase
diagram with two first order transition lines.


title: Effective one-body dynamics in multiple-quantum NMR experiments

abstract:
  A suitable NMR experiment in a one-dimensional dipolar coupled spin system
allows one to reduce the natural many-body dynamics into effective one-body
dynamics. We verify this in a polycrystalline sample of hydroxyapatite (HAp) by
monitoring the excitation of NMR many-body superposition states: the
multiple-quantum coherences. The observed effective one-dimensionality of HAp
relies on the quasi 1d structure of the dipolar coupled network that, as we
show here, is dynamically enhanced by the quantum Zeno effect. Decoherence is
also probed through a Loschmidt echo experiment, where the time reversal is
implemented on the double-quantum Hamiltonian, I_{i,+}I_{j,+} + I_{i,-}I_{j,-}.
We contrast the decoherence of adamantane, a standard 3d system, with that of
HAp. While the first shows an abrupt Fermi-type decay, HAp presents a smooth
exponential law.


title:
A Distance-Limited Imaging Survey of Sub-Stellar Companions to Solar
  Neighborhood Stars

abstract:
  We report techniques and results of a Palomar 200-inch (5 m) adaptive optics
imaging survey of sub-stellar companions to solar-type stars. The survey
consists of Ks coronagraphic observations of 21 FGK dwarfs out to 20 pc (median
distance about 17 pc). At 1-arcsec separation (17 projected AU) from a typical
target system, the survey achieves median sensitivities 7 mag fainter than the
parent star. In terms of companion mass, that corresponds to sensitivities of
50MJ (1 Gyr), 70MJ (solar age), and 75MJ (10 Gyr), using the evolutionary
models of Baraffe and colleagues. Using common proper motion to distinguish
companions from field stars, we find that no system shows positive evidence of
a previously unknown substellar companion (searchable separation about 20-250
projected AU at the median target distance).


title:
Active Galactic Nuclei and Transformation of Dark Matter into Visible
  Matter

abstract:
  The hypothesis that dark matter is converted into visible particles in active
galactic nuclei is investigated. If dark matter consists of stable superheavy
neutral particles and active galactic nuclei are rotating black holes, then,
due to the Penrose process, superheavy particles can decay into unstable
particles with larger mass, whose decay into quarks and leptons leads to events
in cosmic rays observed by the Auger group. Similar processes of decay of
superheavy particles of dark matter into visible matter occurred in the early
Universe. Numerical estimates of the processes in active galactic nuclei and in
the early Universe are given.


title: The Clapping Book

abstract:
  A steady horizontal air stream flows across a book clamped at its downstream
end. Pages lift off to form a growing bent stack whose shape is determined by
the torques associated with aerodynamic forces, weight and elastic resistance
to bending. As more pages lift off to join the bent stack, the increasing
importance of bending rigidity to dynamic pressure eventually causes the book
to clap shut. The process restarts, and self-sustained oscillations emerge.
[Fluid dynamics video]


title: How to Maximize the Capacity of General Quantum Noisy Channels

abstract:
  A general quantum noisy channel is analyzed, wherein the transmitted qubits
may experience symmetry-breaking decoherence, along with memory effects. We
find the optimal basis not to be fully entangled, but a combination of
factorized and partially-entangled states in the presence of memory, asymmetry
and the state-bias of the noise. Capacity-maximization is shown to be
achievable by combining temporal shaping of the transmitted qubits and optimal
basis selection.


title: The QCD Phase Boundary from Quark-Gluon Dynamics

abstract:
  We study one-flavor QCD at finite temperature and chemical potential using
the functional renormalization group. We discuss the chiral phase transition in
QCD and its order with its underlying mechanism in terms of quarks and gluons
and analyze the dependence of the phase transition temperature on small quark
chemical potentials. Our result for the curvature of the phase boundary at
small quark chemical potential relies on only a single input parameter, the
value of the strong coupling at the Z mass scale.


title: The speed of light under the IST and Lorentz Transformations

abstract:
  We expand the IST transformation to three-dimensional Euclidean space and
derive the speed of light under the IST transformation. The switch from the
direction cosines observed in K to those observed in K-prime is surprisingly
smooth. The formulation thus derived maintains the property that the round trip
speed is constant. We further show that under the proper synchronization
convention of K-prime, the one-way speed of light becomes constant.


title: Gaussian Belief Propagation Based Multiuser Detection

abstract:
  In this work, we present a novel construction for solving the linear
multiuser detection problem using the Gaussian Belief Propagation algorithm.
Our algorithm yields an efficient, iterative and distributed implementation of
the MMSE detector. We compare our algorithm's performance to a recent result
and show an improved memory consumption, reduced computation steps and a
reduction in the number of sent messages. We prove that recent work by
Montanari et al. is an instance of our general algorithm, providing new
convergence results for both algorithms.


title: Fractional Order Shapiro Steps in Superconducting Nanowires

abstract:
  We expose superconducting nanowires to microwave radiation in order to study
phase lock-in effects in quasi one dimensional superconductors. For
sufficiently high microwave powers a resistive branch with Shapiro steps
appears in the voltage-current characteristics. At frequencies in the range of
0.9-4 GHz these steps are of integer order only. At higher frequencies steps of
1/2, 1/3, 1/4 and even 1/6 order appear. We numerically model this behavior
using a multi-valued current-phase relationship (CPR) for nanowires.


title: Most actions on regular trees are almost free

abstract:
  Let T be a d-regular tree (d > 2) and A=Aut(T), its automorphism group. Let G
be a group generated by n independent Haar-random elements of A. We show that
almost surely, every nontrivial element of G has finitely many fixed points on
T.


title: Introduction to Searching with Regular Expressions

abstract:
  The explosive rate of information growth and availability often makes it
increasingly difficult to locate information pertinent to your needs. These
problems are often compounded when keyword based search methodologies are not
adequate for describing the information you seek. In many instances,
information such as Web site URLs, phone numbers, etc. can often be better
identified through the use of a textual pattern than by keyword. For example,
many more phone numbers could be picked up by a search for the pattern (XXX)
XXX-XXXX, where X could be any digit, than would be by a search for any
specific phone number (i.e. the keyword approach). Programming languages
typically allow for the matching of textual patterns via the usage of regular
expressions. This tutorial will provide an introduction to the basics of
programming regular expressions as well as provide an introduction to how
regular expressions can be applied to data processing tasks such as information
extraction and search refinement.


title:
Generalized Dynamical Mean-Field Theory for Bose-Fermi Mixtures in
  Optical Lattices

abstract:
  We give a detailed discussion of the recently developed Generalized Dynamical
Mean-Field Theory (GDMFT) for a mixture of bosonic and fermionic particles. We
show that this method is non-perturbative and exact in infinite dimensions and
reliably describes the full range from weak to strong coupling. Like in
conventional Dynamical Mean-Field Theory, the small parameter is 1/z, where z
is the lattice coordination number. We apply the GDMFT scheme to a mixture of
spinless fermions and bosons in an optical lattice. We investigate the
ossibility of a supersolid phase, focussing on the case of 1/2 filling for the
fermions and 3/2 filling for the bosons.


title: Central mass and luminosity of Milky Way satellites in the LCDM model

abstract:
  It has been pointed out that the Galactic satellites all have a common mass
around 1e7 Msun within 300 pc (M03), while they span almost four order of
magnitudes in luminosity (Mateo et al. 1993, Strigari et al. 2008). It is
argued that this may reflect a specific scale for galaxy formation or a scale
for dark matter clustering. Here we use numerical simulations coupled with a
semi-analytic model for galaxy formation, to predict the central mass and
luminosity of galactic satellites in the LCDM model. We show that this common
mass scale can be explained within the Cold Dark Matter scenario when the
physics of galaxy formation is taken into account. The narrow range of M03
comes from the narrow distribution of circular velocities at time of accretion
(peaking around 20 km/s) for satellites able to form stars and the not tight
correlation between halo concentration and circular velocity. The wide range of
satellite luminosities is due to a combination of the mass at time of accretion
and the broad distribution of accretion redshifts for a given mass. This causes
the satellites baryonic content to be suppressed by photo-ionization to very
different extents. Our results favor the argument that the common mass M03
reflects a specific scale (circular velocity ~ 20 km/s) for star formation.